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Publisher: John Wiley and Sons   (Total: 1589 journals)

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Showing 1 - 200 of 1589 Journals sorted alphabetically
Abacus     Hybrid Journal   (Followers: 12, SJR: 0.48, h-index: 22)
About Campus     Hybrid Journal   (Followers: 5)
Academic Emergency Medicine     Hybrid Journal   (Followers: 65, SJR: 1.385, h-index: 91)
Accounting & Finance     Hybrid Journal   (Followers: 47, SJR: 0.547, h-index: 30)
ACEP NOW     Free   (Followers: 1)
Acta Anaesthesiologica Scandinavica     Hybrid Journal   (Followers: 52, SJR: 1.02, h-index: 88)
Acta Archaeologica     Hybrid Journal   (Followers: 164, SJR: 0.101, h-index: 9)
Acta Geologica Sinica (English Edition)     Hybrid Journal   (Followers: 3, SJR: 0.552, h-index: 41)
Acta Neurologica Scandinavica     Hybrid Journal   (Followers: 5, SJR: 1.203, h-index: 74)
Acta Obstetricia et Gynecologica Scandinavica     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 81)
Acta Ophthalmologica     Hybrid Journal   (Followers: 6, SJR: 0.112, h-index: 1)
Acta Paediatrica     Hybrid Journal   (Followers: 56, SJR: 0.794, h-index: 88)
Acta Physiologica     Hybrid Journal   (Followers: 6, SJR: 1.69, h-index: 88)
Acta Polymerica     Hybrid Journal   (Followers: 9)
Acta Psychiatrica Scandinavica     Hybrid Journal   (Followers: 35, SJR: 2.518, h-index: 113)
Acta Zoologica     Hybrid Journal   (Followers: 7, SJR: 0.459, h-index: 29)
Acute Medicine & Surgery     Hybrid Journal   (Followers: 4)
Addiction     Hybrid Journal   (Followers: 35, SJR: 2.086, h-index: 143)
Addiction Biology     Hybrid Journal   (Followers: 14, SJR: 2.091, h-index: 57)
Adultspan J.     Hybrid Journal   (SJR: 0.127, h-index: 4)
Advanced Energy Materials     Hybrid Journal   (Followers: 27, SJR: 6.411, h-index: 86)
Advanced Engineering Materials     Hybrid Journal   (Followers: 26, SJR: 0.81, h-index: 81)
Advanced Functional Materials     Hybrid Journal   (Followers: 51, SJR: 5.21, h-index: 203)
Advanced Healthcare Materials     Hybrid Journal   (Followers: 14, SJR: 0.232, h-index: 7)
Advanced Materials     Hybrid Journal   (Followers: 268, SJR: 9.021, h-index: 345)
Advanced Materials Interfaces     Hybrid Journal   (Followers: 6, SJR: 1.177, h-index: 10)
Advanced Optical Materials     Hybrid Journal   (Followers: 7, SJR: 2.488, h-index: 21)
Advanced Science     Open Access   (Followers: 5)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17, SJR: 2.729, h-index: 121)
Advances in Polymer Technology     Hybrid Journal   (Followers: 13, SJR: 0.344, h-index: 31)
Africa Confidential     Hybrid Journal   (Followers: 21)
Africa Research Bulletin: Economic, Financial and Technical Series     Hybrid Journal   (Followers: 13)
Africa Research Bulletin: Political, Social and Cultural Series     Hybrid Journal   (Followers: 10)
African Development Review     Hybrid Journal   (Followers: 33, SJR: 0.275, h-index: 17)
African J. of Ecology     Hybrid Journal   (Followers: 16, SJR: 0.477, h-index: 39)
Aggressive Behavior     Hybrid Journal   (Followers: 15, SJR: 1.391, h-index: 66)
Aging Cell     Open Access   (Followers: 11, SJR: 4.374, h-index: 95)
Agribusiness : an Intl. J.     Hybrid Journal   (Followers: 3, SJR: 0.627, h-index: 14)
Agricultural and Forest Entomology     Hybrid Journal   (Followers: 16, SJR: 0.925, h-index: 43)
Agricultural Economics     Hybrid Journal   (Followers: 45, SJR: 1.099, h-index: 51)
AIChE J.     Hybrid Journal   (Followers: 32, SJR: 1.122, h-index: 120)
Alcoholism and Drug Abuse Weekly     Hybrid Journal   (Followers: 7)
Alcoholism Clinical and Experimental Research     Hybrid Journal   (Followers: 7, SJR: 1.416, h-index: 125)
Alimentary Pharmacology & Therapeutics     Hybrid Journal   (Followers: 33, SJR: 2.833, h-index: 138)
Alimentary Pharmacology & Therapeutics Symposium Series     Hybrid Journal   (Followers: 3)
Allergy     Hybrid Journal   (Followers: 51, SJR: 3.048, h-index: 129)
Alternatives to the High Cost of Litigation     Hybrid Journal   (Followers: 3)
American Anthropologist     Hybrid Journal   (Followers: 148, SJR: 0.951, h-index: 61)
American Business Law J.     Hybrid Journal   (Followers: 24, SJR: 0.205, h-index: 17)
American Ethnologist     Hybrid Journal   (Followers: 92, SJR: 2.325, h-index: 51)
American J. of Economics and Sociology     Hybrid Journal   (Followers: 29, SJR: 0.211, h-index: 26)
American J. of Hematology     Hybrid Journal   (Followers: 34, SJR: 1.761, h-index: 77)
American J. of Human Biology     Hybrid Journal   (Followers: 12, SJR: 1.018, h-index: 58)
American J. of Industrial Medicine     Hybrid Journal   (Followers: 16, SJR: 0.993, h-index: 85)
American J. of Medical Genetics Part A     Hybrid Journal   (Followers: 16, SJR: 1.115, h-index: 61)
American J. of Medical Genetics Part B: Neuropsychiatric Genetics     Hybrid Journal   (Followers: 4, SJR: 1.771, h-index: 107)
American J. of Medical Genetics Part C: Seminars in Medical Genetics     Partially Free   (Followers: 6, SJR: 2.315, h-index: 79)
American J. of Physical Anthropology     Hybrid Journal   (Followers: 37, SJR: 1.41, h-index: 88)
American J. of Political Science     Hybrid Journal   (Followers: 276, SJR: 5.101, h-index: 114)
American J. of Primatology     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 63)
American J. of Reproductive Immunology     Hybrid Journal   (Followers: 3, SJR: 1.347, h-index: 75)
American J. of Transplantation     Hybrid Journal   (Followers: 17, SJR: 2.792, h-index: 140)
American J. on Addictions     Hybrid Journal   (Followers: 9, SJR: 0.843, h-index: 57)
Anaesthesia     Hybrid Journal   (Followers: 138, SJR: 1.404, h-index: 88)
Analyses of Social Issues and Public Policy     Hybrid Journal   (Followers: 9, SJR: 0.397, h-index: 18)
Analytic Philosophy     Hybrid Journal   (Followers: 18)
Anatomia, Histologia, Embryologia: J. of Veterinary Medicine Series C     Hybrid Journal   (Followers: 3, SJR: 0.295, h-index: 27)
Anatomical Sciences Education     Hybrid Journal   (Followers: 1, SJR: 0.633, h-index: 24)
Andrologia     Hybrid Journal   (Followers: 2, SJR: 0.528, h-index: 45)
Andrology     Hybrid Journal   (Followers: 2, SJR: 0.979, h-index: 14)
Angewandte Chemie     Hybrid Journal   (Followers: 220)
Angewandte Chemie Intl. Edition     Hybrid Journal   (Followers: 222, SJR: 6.229, h-index: 397)
Animal Conservation     Hybrid Journal   (Followers: 41, SJR: 1.576, h-index: 62)
Animal Genetics     Hybrid Journal   (Followers: 8, SJR: 0.957, h-index: 67)
Animal Science J.     Hybrid Journal   (Followers: 6, SJR: 0.569, h-index: 24)
Annalen der Physik     Hybrid Journal   (Followers: 5, SJR: 1.46, h-index: 40)
Annals of Anthropological Practice     Partially Free   (Followers: 2, SJR: 0.187, h-index: 5)
Annals of Applied Biology     Hybrid Journal   (Followers: 7, SJR: 0.816, h-index: 56)
Annals of Clinical and Translational Neurology     Open Access   (Followers: 1)
Annals of Human Genetics     Hybrid Journal   (Followers: 9, SJR: 1.191, h-index: 67)
Annals of Neurology     Hybrid Journal   (Followers: 47, SJR: 5.584, h-index: 241)
Annals of Noninvasive Electrocardiology     Hybrid Journal   (Followers: 1, SJR: 0.531, h-index: 38)
Annals of Public and Cooperative Economics     Hybrid Journal   (Followers: 8, SJR: 0.336, h-index: 23)
Annals of the New York Academy of Sciences     Hybrid Journal   (Followers: 5, SJR: 2.389, h-index: 189)
Annual Bulletin of Historical Literature     Hybrid Journal   (Followers: 13)
Annual Review of Information Science and Technology     Hybrid Journal   (Followers: 14)
Anthropology & Education Quarterly     Hybrid Journal   (Followers: 25, SJR: 0.72, h-index: 31)
Anthropology & Humanism     Hybrid Journal   (Followers: 17, SJR: 0.137, h-index: 3)
Anthropology News     Hybrid Journal   (Followers: 15)
Anthropology of Consciousness     Hybrid Journal   (Followers: 11, SJR: 0.172, h-index: 5)
Anthropology of Work Review     Hybrid Journal   (Followers: 11, SJR: 0.256, h-index: 5)
Anthropology Today     Hybrid Journal   (Followers: 89, SJR: 0.545, h-index: 15)
Antipode     Hybrid Journal   (Followers: 49, SJR: 2.212, h-index: 69)
Anz J. of Surgery     Hybrid Journal   (Followers: 8, SJR: 0.432, h-index: 59)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apmis     Hybrid Journal   (Followers: 1, SJR: 0.855, h-index: 73)
Applied Cognitive Psychology     Hybrid Journal   (Followers: 70, SJR: 0.754, h-index: 69)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7, SJR: 0.632, h-index: 58)
Applied Psychology     Hybrid Journal   (Followers: 206, SJR: 1.023, h-index: 64)
Applied Psychology: Health and Well-Being     Hybrid Journal   (Followers: 49, SJR: 0.868, h-index: 13)
Applied Stochastic Models in Business and Industry     Hybrid Journal   (Followers: 5, SJR: 0.613, h-index: 24)
Aquaculture Nutrition     Hybrid Journal   (Followers: 14, SJR: 1.025, h-index: 55)
Aquaculture Research     Hybrid Journal   (Followers: 31, SJR: 0.807, h-index: 60)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 36, SJR: 1.047, h-index: 57)
Arabian Archaeology and Epigraphy     Hybrid Journal   (Followers: 11, SJR: 0.453, h-index: 11)
Archaeological Prospection     Hybrid Journal   (Followers: 12, SJR: 0.922, h-index: 21)
Archaeology in Oceania     Hybrid Journal   (Followers: 13, SJR: 0.745, h-index: 18)
Archaeometry     Hybrid Journal   (Followers: 27, SJR: 0.809, h-index: 48)
Archeological Papers of The American Anthropological Association     Hybrid Journal   (Followers: 15, SJR: 0.156, h-index: 2)
Architectural Design     Hybrid Journal   (Followers: 25, SJR: 0.261, h-index: 9)
Archiv der Pharmazie     Hybrid Journal   (Followers: 3, SJR: 0.628, h-index: 43)
Archives of Drug Information     Hybrid Journal   (Followers: 5)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (SJR: 0.768, h-index: 54)
Area     Hybrid Journal   (Followers: 12, SJR: 0.938, h-index: 57)
Art History     Hybrid Journal   (Followers: 245, SJR: 0.153, h-index: 13)
Arthritis & Rheumatology     Hybrid Journal   (Followers: 52, SJR: 1.984, h-index: 20)
Arthritis Care & Research     Hybrid Journal   (Followers: 27, SJR: 2.256, h-index: 114)
Artificial Organs     Hybrid Journal   (Followers: 1, SJR: 0.872, h-index: 60)
ASHE Higher Education Reports     Hybrid Journal   (Followers: 15)
Asia & the Pacific Policy Studies     Open Access   (Followers: 16)
Asia Pacific J. of Human Resources     Hybrid Journal   (Followers: 320, SJR: 0.494, h-index: 19)
Asia Pacific Viewpoint     Hybrid Journal   (Followers: 1, SJR: 0.616, h-index: 26)
Asia-Pacific J. of Chemical Engineering     Hybrid Journal   (Followers: 8, SJR: 0.345, h-index: 20)
Asia-pacific J. of Clinical Oncology     Hybrid Journal   (Followers: 6, SJR: 0.554, h-index: 14)
Asia-Pacific J. of Financial Studies     Hybrid Journal   (SJR: 0.241, h-index: 7)
Asia-Pacific Psychiatry     Hybrid Journal   (Followers: 4, SJR: 0.377, h-index: 7)
Asian Economic J.     Hybrid Journal   (Followers: 8, SJR: 0.234, h-index: 21)
Asian Economic Policy Review     Hybrid Journal   (Followers: 4, SJR: 0.196, h-index: 12)
Asian J. of Control     Hybrid Journal   (SJR: 0.862, h-index: 34)
Asian J. of Endoscopic Surgery     Hybrid Journal   (SJR: 0.394, h-index: 7)
Asian J. of Organic Chemistry     Hybrid Journal   (Followers: 6, SJR: 1.443, h-index: 19)
Asian J. of Social Psychology     Hybrid Journal   (Followers: 5, SJR: 0.665, h-index: 37)
Asian Politics and Policy     Hybrid Journal   (Followers: 12, SJR: 0.207, h-index: 7)
Asian Social Work and Policy Review     Hybrid Journal   (Followers: 5, SJR: 0.318, h-index: 5)
Asian-pacific Economic Literature     Hybrid Journal   (Followers: 5, SJR: 0.168, h-index: 15)
Assessment Update     Hybrid Journal   (Followers: 4)
Astronomische Nachrichten     Hybrid Journal   (Followers: 2, SJR: 0.701, h-index: 40)
Atmospheric Science Letters     Open Access   (Followers: 29, SJR: 1.332, h-index: 27)
Austral Ecology     Hybrid Journal   (Followers: 15, SJR: 1.095, h-index: 66)
Austral Entomology     Hybrid Journal   (Followers: 9, SJR: 0.524, h-index: 28)
Australasian J. of Dermatology     Hybrid Journal   (Followers: 8, SJR: 0.714, h-index: 40)
Australasian J. On Ageing     Hybrid Journal   (Followers: 6, SJR: 0.39, h-index: 22)
Australian & New Zealand J. of Statistics     Hybrid Journal   (Followers: 14, SJR: 0.275, h-index: 28)
Australian Accounting Review     Hybrid Journal   (Followers: 3, SJR: 0.709, h-index: 14)
Australian and New Zealand J. of Family Therapy (ANZJFT)     Hybrid Journal   (Followers: 3, SJR: 0.382, h-index: 12)
Australian and New Zealand J. of Obstetrics and Gynaecology     Hybrid Journal   (Followers: 47, SJR: 0.814, h-index: 49)
Australian and New Zealand J. of Public Health     Hybrid Journal   (Followers: 11, SJR: 0.82, h-index: 62)
Australian Dental J.     Hybrid Journal   (Followers: 7, SJR: 0.482, h-index: 46)
Australian Economic History Review     Hybrid Journal   (Followers: 5, SJR: 0.171, h-index: 12)
Australian Economic Papers     Hybrid Journal   (Followers: 31, SJR: 0.23, h-index: 9)
Australian Economic Review     Hybrid Journal   (Followers: 6, SJR: 0.357, h-index: 21)
Australian Endodontic J.     Hybrid Journal   (Followers: 3, SJR: 0.513, h-index: 24)
Australian J. of Agricultural and Resource Economics     Hybrid Journal   (Followers: 3, SJR: 0.765, h-index: 36)
Australian J. of Grape and Wine Research     Hybrid Journal   (Followers: 5, SJR: 0.879, h-index: 56)
Australian J. of Politics & History     Hybrid Journal   (Followers: 14, SJR: 0.203, h-index: 14)
Australian J. of Psychology     Hybrid Journal   (Followers: 18, SJR: 0.384, h-index: 30)
Australian J. of Public Administration     Hybrid Journal   (Followers: 406, SJR: 0.418, h-index: 29)
Australian J. of Rural Health     Hybrid Journal   (Followers: 5, SJR: 0.43, h-index: 34)
Australian Occupational Therapy J.     Hybrid Journal   (Followers: 72, SJR: 0.59, h-index: 29)
Australian Psychologist     Hybrid Journal   (Followers: 12, SJR: 0.331, h-index: 31)
Australian Veterinary J.     Hybrid Journal   (Followers: 21, SJR: 0.459, h-index: 45)
Autism Research     Hybrid Journal   (Followers: 36, SJR: 2.126, h-index: 39)
Autonomic & Autacoid Pharmacology     Hybrid Journal   (SJR: 0.371, h-index: 29)
Banks in Insurance Report     Hybrid Journal   (Followers: 1)
Basic & Clinical Pharmacology & Toxicology     Hybrid Journal   (Followers: 11, SJR: 0.539, h-index: 70)
Basic and Applied Pathology     Open Access   (Followers: 2, SJR: 0.113, h-index: 4)
Basin Research     Hybrid Journal   (Followers: 5, SJR: 1.54, h-index: 60)
Bauphysik     Hybrid Journal   (Followers: 2, SJR: 0.194, h-index: 5)
Bauregelliste A, Bauregelliste B Und Liste C     Hybrid Journal  
Bautechnik     Hybrid Journal   (Followers: 1, SJR: 0.321, h-index: 11)
Behavioral Interventions     Hybrid Journal   (Followers: 9, SJR: 0.297, h-index: 23)
Behavioral Sciences & the Law     Hybrid Journal   (Followers: 24, SJR: 0.736, h-index: 57)
Berichte Zur Wissenschaftsgeschichte     Hybrid Journal   (Followers: 10, SJR: 0.11, h-index: 5)
Beton- und Stahlbetonbau     Hybrid Journal   (Followers: 2, SJR: 0.493, h-index: 14)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 6, SJR: 0.311, h-index: 26)
Bioelectromagnetics     Hybrid Journal   (Followers: 1, SJR: 0.568, h-index: 64)
Bioengineering & Translational Medicine     Open Access  
BioEssays     Hybrid Journal   (Followers: 10, SJR: 3.104, h-index: 155)
Bioethics     Hybrid Journal   (Followers: 14, SJR: 0.686, h-index: 39)
Biofuels, Bioproducts and Biorefining     Hybrid Journal   (Followers: 1, SJR: 1.725, h-index: 56)
Biological J. of the Linnean Society     Hybrid Journal   (Followers: 16, SJR: 1.172, h-index: 90)
Biological Reviews     Hybrid Journal   (Followers: 4, SJR: 6.469, h-index: 114)
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 41, SJR: 0.12, h-index: 1)
Biology of the Cell     Full-text available via subscription   (Followers: 9, SJR: 1.812, h-index: 69)
Biomedical Chromatography     Hybrid Journal   (Followers: 6, SJR: 0.572, h-index: 49)
Biometrical J.     Hybrid Journal   (Followers: 5, SJR: 0.784, h-index: 44)
Biometrics     Hybrid Journal   (Followers: 37, SJR: 1.906, h-index: 96)
Biopharmaceutics and Drug Disposition     Hybrid Journal   (Followers: 10, SJR: 0.715, h-index: 44)
Biopolymers     Hybrid Journal   (Followers: 18, SJR: 1.199, h-index: 104)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 44, SJR: 0.415, h-index: 55)
Biotechnology and Bioengineering     Hybrid Journal   (Followers: 141, SJR: 1.633, h-index: 146)
Biotechnology J.     Hybrid Journal   (Followers: 14, SJR: 1.185, h-index: 51)
Biotechnology Progress     Hybrid Journal   (Followers: 39, SJR: 0.736, h-index: 101)
Biotropica     Hybrid Journal   (Followers: 20, SJR: 1.374, h-index: 71)
Bipolar Disorders     Hybrid Journal   (Followers: 9, SJR: 2.592, h-index: 100)
Birth     Hybrid Journal   (Followers: 38, SJR: 0.763, h-index: 64)
Birth Defects Research Part A : Clinical and Molecular Teratology     Hybrid Journal   (Followers: 2, SJR: 0.727, h-index: 77)
Birth Defects Research Part B: Developmental and Reproductive Toxicology     Hybrid Journal   (Followers: 6, SJR: 0.468, h-index: 47)
Birth Defects Research Part C : Embryo Today : Reviews     Hybrid Journal   (SJR: 1.513, h-index: 55)
BJOG : An Intl. J. of Obstetrics and Gynaecology     Partially Free   (Followers: 243, SJR: 2.083, h-index: 125)

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Journal Cover Advanced Energy Materials
  [SJR: 6.411]   [H-I: 86]   [27 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Online) 1614-6840
   Published by John Wiley and Sons Homepage  [1589 journals]
  • High Thermoelectric zT in n-Type Silver Selenide films at Room Temperature
    • Authors: Jaime Andres Perez-Taborda; Olga Caballero-Calero, Liliana Vera-Londono, Fernando Briones, Marisol Martin-Gonzalez
      Abstract: In this work, a zT value as high as 1.2 at room temperature for n-type Ag2Se films is reported grown by pulsed hybrid reactive magnetron sputtering (PHRMS). PHRMS is a novel technique developed in the lab that allows to grow film of selenides with different compositions in a few minutes with great quality. The improved zT value reported for room temperature results from the combination of the high power factors, similar to the best values reported for bulk Ag2Se (2440 ± 192 µW m−1 K−2), along with a reduced thermoelectric conductivity as low as 0.64 ± 0.1 W m−1 K−1. The maximum power factor for these films is of 4655 ± 407 µW m−1 K−2 at 103 °C. This material shows promise to work for room temperature applications. Obtaining high zT or, in other words, high power factor and low thermal conductivity values close to room temperature for thin films is of high importance to develop a new generation of wearable devices based on thermoelectric heat recovery.A zT value as high as 1.2 at room temperature for n-type Ag2Se films grown by pulsed hybrid reactive magnetron sputtering is reported. Obtaining such high zT for thin films with this new fabrication method that allows the use of flexible substrates is of high importance to develop a new generation of wearable devices based on thermoelectric heat recovery.
      PubDate: 2017-12-05T02:00:02.510371-05:
      DOI: 10.1002/aenm.201702024
  • Balancing High Open Circuit Voltage over 1.0 V and High Short Circuit
           Current in Benzodithiophene-Based Polymer Solar Cells with Low Energy
           Loss: A Synergistic Effect of Fluorination and Alkylthiolation
    • Authors: Zhengkun Du; Xichang Bao, Yonghai Li, Deyu Liu, Jiuxing Wang, Chunming Yang, Reinhard Wimmer, Lars Wagner Städe, Renqiang Yang, Donghong Yu
      Abstract: Based on the most recently significant progress within the last one year in organic photovoltaic research from either alkylthiolation or fluorination on benzo[1,2-b:4,5-b′]dithiophene moiety for high efficiency polymer solar cells (PSCs), two novel simultaneously fluorinated and alkylthiolated benzo[1,2-b:4,5-b′] dithiophene (BDT)-based donor–acceptor (D–A) polymers, poly(4,8-bis(5′-((2″-ethylhexyl)thio)-4′-fluorothiophen-2′-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)-alt-2′-ethylhexyl-3-fluorothieno[3,4-b]thiophene-2-carboxylate (PBDTT-SF-TT) and poly(4,8-bis(5′-((2″-ethylhexyl)thio)-4′-fluorothiophen-2′-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)-alt-1,3-bis(thiophen-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c′]dithiophene-4,8-dione (PBDTT-SF-BDD), namely, via an advantageous and synthetically economic route for the key monomer are reported herein. Synergistic effects of fluorination and alkylthiolation on BDT moieties are discussed in detail, which is based on the superior balance between high Voc and large Jsc when PBDTT-SF-TT/PC71BM and PBDTT-SF-BDD/PC71BM solar cells present their high Voc as 1.00 and 0.97 V (associated with their deep highest occupied molecular orbital level of −5.54 and −5.61 eV), a moderately high Jsc of 14.79 and 14.70 mA cm−2, and thus result a high power conversion efficiency of 9.07% and 9.72%, respectively. Meanwhile, for PBDTT-SF-TT, a very low energy loss of 0.59 eV is pronounced, leading to the promisingly high voltage, and furthermore performance study and morphological results declare an additive-free PSC from PBDTT-SF-TT, which is beneficial to practical applications.Superior balance between high Voc and large Jsc is realized via synergistic effect of fluorination and alkylthiolation on benzo[1,2-b:4,5-b′] dithiophene (BDT) moiety, leading to new efficient conventional BDT-based polymer solar cells are achieved with high power conversion efficiency of 9.07% for poly(4,8-bis(5′-((2″-ethylhexyl)thio)-4′-fluorothiophen-2′-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)-alt-2′-ethylhexyl-3-fluorothieno[3,4-b]thiophene-2-carboxylate and 9.72% for poly(4,8-bis(5′-((2″-ethylhexyl)thio)-4′-fluorothiophen-2′-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)-alt-1,3-bis(thiophen-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c′]dithiophene-4,8-dione.
      PubDate: 2017-12-04T06:07:03.405822-05:
      DOI: 10.1002/aenm.201701471
  • Quantifying Efficiency Loss of Perovskite Solar Cells by a Modified
           Detailed Balance Model
    • Authors: Wei E. I. Sha; Hong Zhang, Zi Shuai Wang, Hugh L. Zhu, Xingang Ren, Francis Lin, Alex K.-Y. Jen, Wallace C. H. Choy
      Abstract: A modified detailed balance model is built to understand and quantify efficiency loss of perovskite solar cells. The modified model captures the light-absorption-dependent short-circuit current, contact and transport-layer-modified carrier transport, as well as recombination and photon-recycling-influenced open-circuit voltage. The theoretical and experimental results show that for experimentally optimized perovskite solar cells with the power conversion efficiency of 19%, optical loss of 25%, nonradiative recombination loss of 35%, and ohmic loss of 35% are the three dominant loss factors for approaching the 31% efficiency limit of perovskite solar cells. It is also found that the optical loss climbs up to 40% for a thin-active-layer design. Moreover, a misconfigured transport layer introduces above 15% of energy loss. Finally, the perovskite-interface-induced surface recombination, ohmic loss, and current leakage should be further reduced to upgrade device efficiency and eliminate hysteresis effect. This work contributes to fundamental understanding of device physics of perovskite solar cells. The developed model offers a systematic design and analysis tool to photovoltaic science and technology.A modified detailed balance model is built to understand and quantify the efficiency loss of perovskite solar cells. The optical loss, nonradiative recombination loss, and ohmic loss are identified quantitatively. The perovskite-interface-induced surface recombination, ohmic loss, and current leakage are also analyzed.
      PubDate: 2017-12-04T06:05:34.622809-05:
      DOI: 10.1002/aenm.201701586
  • 3D TiC/C Core/Shell Nanowire Skeleton for Dendrite-Free and Long-Life
           Lithium Metal Anode
    • Authors: Sufu Liu; Xinhui Xia, Yu Zhong, Shengjue Deng, Zhujun Yao, Liyuan Zhang, Xin-Bing Cheng, Xiuli Wang, Qiang Zhang, Jiangping Tu
      Abstract: Construction of stable dendrite-free Li metal anode is crucial for the development of advanced Li–S and Li–air batteries. Herein, self-supported TiC/C core/shell nanowire arrays as skeletons and confined hosts of molten Li forming integrated trilayer TiC/C/Li anode are described. The TiC/C core/shell nanowires with diameters of 400–500 nm exhibit merits of good lithiophilicity, high electrical conductivity, and abundant porosity. The as-prepared TiC/C/Li anode exhibits prominent electrochemical performance with a small hysteresis of less than 85 mV beyond 200 cycles (3.0 mA cm−2) as well as a very high Coulombic efficiency up to 98.5% for 100 cycles at 1.0 mA cm−2. When the structured anode is coupled with lithium iron phosphate or sulfur cathode, the assembled full cells with trilayer TiC/C/Li anodes display enhanced capability retention and improved Coulombic efficiency. This is ascribed to the unique TiC/C matrix, which can not only provide interspace for accommodating “hostless” Li, but also afford interconnected rapid transfer paths for electrons and ions with low local current densities, leading to effective inhabitation growth of Li dendrites and lower interfacial resistance. A fresh way for construction of advanced stable Li metal anodes is provided in this work.A unique integrated trilayer TiC/C/Li anode is constructed through rational combination of self-supported TiC/C core/shell nanowire arrays and melt-infusion process. Attributed to ultralow current density, stabilized solid electrolyte interphase film, and limited volume change, the TiC/C/Li anode exhibits lower hysteresis, enhanced cycling stability, and higher Coulombic efficiency.
      PubDate: 2017-12-04T06:02:41.395039-05:
      DOI: 10.1002/aenm.201702322
  • Alkaline Benzoquinone Aqueous Flow Battery for Large-Scale Storage of
           Electrical Energy
    • Authors: Zhengjin Yang; Liuchuan Tong, Daniel P. Tabor, Eugene S. Beh, Marc-Antoni Goulet, Diana Porcellinis, Alán Aspuru-Guzik, Roy G. Gordon, Michael J. Aziz
      Abstract: An aqueous flow battery based on low-cost, nonflammable, noncorrosive, and earth-abundant elements is introduced. During charging, electrons are stored in a concentrated water solution of 2,5-dihydroxy-1,4-benzoquinone, which rapidly receives electrons with inexpensive carbon electrodes without the assistance of any metal electrocatalyst. Electrons are withdrawn from a second water solution of a food additive, potassium ferrocyanide. When these two solutions flow along opposite sides of a cation-conducting membrane, this flow battery delivers a cell potential of 1.21 V, a peak galvanic power density of 300 mW cm−2, and a coulombic efficiency exceeding 99%. Continuous cell cycling at 100 mA cm−2 shows a capacity retention rate of 99.76% cycle−1 over 150 cycles. Various molecular modifications involving substitution for hydrogens on the aryl ring are implemented to block decomposition by nucleophilic attack of hydroxide ions. These modifications result in increased capacity retention rates of up to 99.96% cycle−1 over 400 consecutive cycles, accompanied by changes in voltage, solubility, kinetics, and cell resistance. Quantum chemistry calculations of a large number of organic compounds predict a number of related structures that should have even higher performance and stability. Flow batteries based on alkaline-soluble dihydroxybenzoquinones and derivatives are promising candidates for large-scale, stationary storage of electrical energy.Redox-active and cheap benzoquinone materials that store energy in considerably smaller volumes are reported. When paired with potassium ferrocyanide, an inexpensive and safe food additive, this flow battery chemistry delivers a cell potential of 1.21 V and a peak galvanic power density of 300 mW cm−2. Quantum computational simulation has also identified promising compounds for future improvements.
      PubDate: 2017-12-04T06:01:56.645509-05:
      DOI: 10.1002/aenm.201702056
  • n-Type SnSe2 Oriented-Nanoplate-Based Pellets for High Thermoelectric
    • Authors: Yubo Luo; Yun Zheng, Zhongzhen Luo, Shiqiang Hao, Chengfeng Du, Qinghua Liang, Zhong Li, Khiam Aik Khor, Kedar Hippalgaonkar, Jianwei Xu, Qingyu Yan, Chris Wolverton, Mercouri G. Kanatzidis
      Abstract: It is reported that electron doped n-type SnSe2 nanoplates show promising thermoelectric performance at medium temperatures. After simultaneous introduction of Se deficiency and Cl doping, the Fermi level of SnSe2 shifts toward the conduction band, resulting in two orders of magnitude increase in carrier concentration and a transition to degenerate transport behavior. In addition, all-scale hierarchical phonon scattering centers, such as point defects, nanograin boundaries, stacking faults, and the layered nanostructures, cooperate to produce very low lattice thermal conductivity. As a result, an enhanced in-plane thermoelectric figure of merit ZTmax of 0.63 is achieved for a 1.5 at% Cl doped SnSe1.95 pellet at 673 K, which is much higher than the corresponding in-plane ZT of pure SnSe2 (0.08).A novel ecofriendly n-type SnSe2 oriented-nanoplate-based thermoelectric material is demonstrated. A high power factor is achieved through defect chemistry and a low thermal conductivity is achieved by all-scale hierarchical phonon scattering. Taken together, an enhanced in-plane thermoelectric figure of merit ZTmax of 0.63 is achieved for a 1.5 at% Cl doped SnSe1.95 pellet at 673 K.
      PubDate: 2017-12-04T06:01:39.897571-05:
      DOI: 10.1002/aenm.201702167
  • 3D Amorphous Carbon with Controlled Porous and Disordered Structures as a
           High-Rate Anode Material for Sodium-Ion Batteries
    • Authors: Peng Lu; Yi Sun, Hongfa Xiang, Xin Liang, Yan Yu
      Abstract: Sodium-ion batteries (SIBs) have a promising application prospect for energy storage systems due to the abundant resource. Amorphous carbon with high electronic conductivity and high surface area is likely to be the most promising anode material for SIBs. However, the rate capability of amorphous carbon in SIBs is still a big challenge because of the sluggish kinetics of Na+ ions. Herein, a three-dimensional amorphous carbon (3DAC) with controlled porous and disordered structures is synthesized via a facile NaCl template-assisted method. Combination of open porous structures of 3DAC, the increased disordered structures can not only facilitate the diffusion of Na+ ions but also enhance the reversible capacity of Na storage. When applied as anode materials for SIBs, 3DAC exhibits excellent rate capability (66 mA h g−1 at 9.6 A g−1) and high reversible capacity (280 mA h g−1 at a low current density of 0.03 A g−1). Moreover, the controlled porous structures by the NaCl template method provide an appropriate specific surface area, which contributes to a relatively high initial Coulombic efficiency of 75%. Additionally, the high-rate 3DAC material is prepared via a green approach originating from low-cost pitch and NaCl template, demonstrating an appealing development of carbon anode materials for SIBs.A 3D amorphous carbon (3DAC) with controlled porous and disordered structures is prepared via a facile NaCl template-assisted method. As anode material for sodium-ion batteries, 3DAC exhibits excellent rate capability (66 mA h g−1 at 9.6 A g−1) and high reversible capacity (280 mA h g−1 at 0.03 A g−1) as well as relatively high initial Coulombic efficiency of 75%.
      PubDate: 2017-12-04T06:00:53.173822-05:
      DOI: 10.1002/aenm.201702434
  • Protons Enhance Conductivities in Lithium Halide Hydroxide/Lithium
           Oxyhalide Solid Electrolytes by Forming Rotating Hydroxy Groups
    • Authors: Ah-Young Song; Yiran Xiao, Kostiantyn Turcheniuk, Punith Upadhya, Anirudh Ramanujapuram, Jim Benson, Alexandre Magasinski, Marco Olguin, Lamartine Meda, Oleg Borodin, Gleb Yushin
      Abstract: Li-halide hydroxides (Li2OHX) and Li-oxyhalides (Li3OX) have emerged as new classes of low-cost, lightweight solid state electrolytes (SSE) showing promising Li-ion conductivities. The similarity in the lattice parameters between them, careless synthesis, and insufficient rigor in characterization often lead to erroneous interpretations of their compositions. Finally, moisture remaining in the synthesis or cell assembling environment and variability in the equivalent circuit models additionally contribute to significant errors in their properties. Thus, there remains a controversy about the real values of Li-ion conductivities in such SSEs. Here an ultra-fast synthesis and comprehensive material characterization is utilized to report on the ionic conductivities of contaminant-free Li2+xOH1−xCl (x=0-0.7), and Li2OHBr not exceeding 10-4 S cm-1 at 110 °C. Using powerful combination of experimental and numerical approaches, it is demonstrated that the presence of H in these SSEs yields significantly higher Li+ -ionic conductivity. Born-Oppenheimer molecular dynamics simulations show excellent agreement with experimental results and reveal an unexpected mechanism for faster Li+ transport. It involves rotation of a short OH-group in SSEs, which opens lower-energy pathways for the formation of Frenkel defects and highly-correlated Li+ jumps. These findings will reduce the existing confusions and show new avenues for tuning SSE compositions for further improved Li-ion conductivities.Ultrafast and well-controlled synthesis, comprehensive material characterization techniques, and a combination of experimental and modeling efforts reveal a significant impact of protons on the ionic conductivities of low-cost lithium halide hydroxide/lithium oxyhalide solid state electrolytes (SSEs). Born–Oppenheimer molecular dynamics simulations revealed the link between OH- group and Li+ transport, which resembles rotating doors in buildings.
      PubDate: 2017-12-04T03:42:43.738485-05:
      DOI: 10.1002/aenm.201700971
  • Effect of Alkylsilyl Side-Chain Structure on Photovoltaic Properties of
           Conjugated Polymer Donors
    • Authors: Haijun Bin; Yankang Yang, Zhengxing Peng, Long Ye, Jia Yao, Lian Zhong, Chenkai Sun, Liang Gao, He Huang, Xiaojun Li, Beibei Qiu, Lingwei Xue, Zhi-Guo Zhang, Harald Ade, Yongfang Li
      Abstract: Side-chain engineering is an important strategy for optimizing photovoltaic properties of organic photovoltaic materials. In this work, the effect of alkylsilyl side-chain structure on the photovoltaic properties of medium bandgap conjugated polymer donors is studied by synthesizing four new polymers J70, J72, J73, and J74 on the basis of highly efficient polymer donor J71 by changing alkyl substituents of the alkylsilyl side chains of the polymers. And the photovoltaic properties of the five polymers are studied by fabricating polymer solar cells (PSCs) with the polymers as donor and an n-type organic semiconductor (n-OS) m-ITIC as acceptor. It is found that the shorter and linear alkylsilyl side chain could afford ordered molecular packing, stronger absorption coefficient, higher charge carrier mobility, thus results in higher Jsc and fill factor values in the corresponding PSCs. While the polymers with longer or branched alkyl substituents in the trialkylsilyl group show lower-lying highest occupied molecular orbital energy levels which leads to higher Voc of the PSCs. The PSCs based on J70:m-ITIC and J71:m-ITIC achieve power conversion efficiency (PCE) of 11.62 and 12.05%, respectively, which are among the top values of the PSCs reported in the literatures so far.Side-chain engineering is performed to optimize photovoltaic properties of the 2D-conjugated polymer donors. The polymer solar cells with m-ITIC as acceptor and J70 and J71 polymer donors with shorter and linear alkyl substituents in their alkylsilyl side chains achieve power conversion efficiency of 11.62% and 12.05%, respectively.
      PubDate: 2017-12-04T03:38:14.477999-05:
      DOI: 10.1002/aenm.201702324
  • Aqueous-Processed Polymer/Nanocrystal Hybrid Solar Cells with Double-Side
           Bulk Heterojunction
    • Authors: Gan Jin; Nannan Chen, Qingsen Zeng, Fangyuan Liu, Wei Yuan, Siyuan Xiang, Tanglue Feng, Xiaohang Du, Tianjiao Ji, Lijing Wang, Yaohua Wang, Henan Sun, Haizhu Sun, Bai Yang
      Abstract: Aqueous-solution-processed solar cells (ASCs) are promising candidates of the next-generation large-area, low-cost, and flexible photovoltaic conversion equipment because of their unique environmental friendly property. Aqueous-solution-processed polymer/nanocrystals (NCs) hybrid solar cells (AHSCs) can effectively integrate the advantages of the polymer (e.g., flexibility and lightweight) and the inorganic NCs (e.g., high mobility and broad absorption), and therefore be considered as an ideal system to further improve the performance of ASCs. In this work, double-side bulk heterojunction (BHJ), in which one BHJ combines the active material with electron transport material and the other combines the active material with hole transport material, is developed in the AHSCs. Through comparing with the single-side BHJ device, promoted carrier extraction, enhanced internal quantum efficiency, extended width of the depletion region, and prolonged carrier lifetime are achieved in double-side BHJ devices. As a result, power conversion efficiency exceeding 6% is obtained, which breaks the bottleneck efficiency around ≈5.5%. This work demonstrates a device architecture which is more remarkable compared with the traditional only donor–acceptor blended BHJ. Under conservative estimation, it provides instructive architecture not only in the ASCs, but also in the organic solar cells (SCs), quantum dot SCs, and perovskite SCs.A double-side bulk heterojunction (BHJ) is developed in the aqueous-solution-processed solar cells (ASCs). Through comparing with the single-side BHJ device, promoted carrier extraction, enhanced internal quantum efficiency, extended width of the depletion region, and prolonged carrier lifetime are achieved in double-side BHJ devices. As a result, power conversion efficiency exceeding 6% is obtained, which breaks the bottleneck efficiency around ≈5.5% in the ASCs.
      PubDate: 2017-12-04T03:37:10.413963-05:
      DOI: 10.1002/aenm.201701966
  • High-Performance Solar Steam Device with Layered Channels: Artificial Tree
           with a Reversed Design
    • Authors: He Liu; Chaoji Chen, Guang Chen, Yudi Kuang, Xinpeng Zhao, Jianwei Song, Chao Jia, Xu Xu, Emily Hitz, Hua Xie, Sha Wang, Feng Jiang, Tian Li, Yiju Li, Amy Gong, Ronggui Yang, Siddhartha Das, Liangbing Hu
      Abstract: Solar steam generation, combining the most abundant resources of solar energy and unpurified water, has been regarded as one of the most promising techniques for water purification. Here, an artificial tree with a reverse-tree design is demonstrated as a cost-effective, scalable yet highly efficient steam-generation device. The reverse-tree design implies that the wood is placed on the water with the tree-growth direction parallel to the water surface; accordingly, water is transported in a direction perpendicular to what occurs in natural tree. The artificial tree is fabricated by cutting the natural tree along the longitudinal direction followed by surface carbonization (called as C-L-Wood). The nature-made 3D interconnected micro-/nanochannels enable efficient water transpiration, while the layered channels block the heat effectively. A much lower thermal conductivity (0.11 W m−1 K−1) thus can be achieved, only 1/3 of that of the horizontally cut wood. Meanwhile, the carbonized surface can absorb almost all the incident light. The simultaneous optimizations of water transpiration, thermal management, and light absorption results in a high efficiency of 89% at 10 kW m−2, among the highest values in literature. Such wood-based high-performance, cost-effective, scalable steam-generation device can provide an attractive solution to the pressing global clean water shortage problem.Solar steam generation has been regarded as one of the most promising techniques for water purification. An artificial tree is demonstrated with a reverse-tree design as a cost-effective, scalable yet highly efficient steam-generation device. Such steam-generation device can provide an attractive solution to the pressing global clean water shortage problem.
      PubDate: 2017-12-04T03:36:06.491223-05:
      DOI: 10.1002/aenm.201701616
  • Effect of Cation Composition on the Mechanical Stability of Perovskite
           Solar Cells
    • Authors: Nicholas Rolston; Adam D. Printz, Jared M. Tracy, Hasitha C. Weerasinghe, Doojin Vak, Lew Jia Haur, Anish Priyadarshi, Nripan Mathews, Daniel J. Slotcavage, Michael D. McGehee, Roghi E. Kalan, Kenneth Zielinski, Ronald L. Grimm, Hsinhan Tsai, Wanyi Nie, Aditya D. Mohite, Somayeh Gholipour, Michael Saliba, Michael Grätzel, Reinhold H. Dauskardt
      Abstract: Photoactive perovskite semiconductors are highly tunable, with numerous inorganic and organic cations readily incorporated to modify optoelectronic properties. However, despite the importance of device reliability and long service lifetimes, the effects of various cations on the mechanical properties of perovskites are largely overlooked. In this study, the cohesion energy of perovskites containing various cation combinations of methylammonium, formamidinium, cesium, butylammonium, and 5-aminovaleric acid is reported. A trade-off is observed between the mechanical integrity and the efficiency of perovskite devices. High efficiency devices exhibit decreased cohesion, which is attributed to reduced grain sizes with the inclusion of additional cations and PbI2 additives. Microindentation hardness testing is performed to estimate the fracture toughness of single-crystal perovskite, and the results indicated perovskites are inherently fragile, even in the absence of grain boundaries and defects. The devices found to have the highest fracture energies are perovskites infiltrated into a porous TiO2/ZrO2/C triple layer, which provide extrinsic reinforcement and shielding for enhanced mechanical and chemical stability.As reflected in the fragility of state-of-the-art perovskite solar cells, mechanical reliability has too long been an afterthought in their development. The aim of this work is to understand the effects of cation composition (combinations of methylammonium, formamidinium, cesium, butylammonium, and 5-aminovaleric acid) on perovskite mechanical integrity and determine design criteria to increase reliability toward the development of module-scale devices.
      PubDate: 2017-12-04T03:35:30.858918-05:
      DOI: 10.1002/aenm.201702116
  • Review on Challenges and Recent Advances in the Electrochemical
           Performance of High Capacity Li- and Mn-Rich Cathode Materials for Li-Ion
    • Authors: Prasant Kumar Nayak; Evan M. Erickson, Florian Schipper, Tirupathi Rao Penki, Nookala Munichandraiah, Philipp Adelhelm, Hadar Sclar, Francis Amalraj, Boris Markovsky, Doron Aurbach
      Abstract: Li and Mn-rich layered oxides, xLi2MnO3·(1–x)LiMO2 (M=Ni, Mn, Co), are promising cathode materials for Li-ion batteries because of their high specific capacity that can exceed 250 mA h g−1. However, these materials suffer from high 1st cycle irreversible capacity, gradual capacity fading, low rate capability, a substantial charge-discharge voltage hysteresis, and a large average discharge voltage decay during cycling. The latter detrimental phenomenon is ascribed to irreversible structural transformations upon cycling of these cathodes related to potentials ≥4.5 V required for their charging. Transition metal inactivation along with impedance increase and partial layered-to-spinel transformation during cycling are possible reasons for the detrimental voltage fade. Doping of Li, Mn-rich materials by Na, Mg, Al, Fe, Co, Ru, etc. is useful for stabilizing capacity and mitigating the discharge-voltage decay of xLi2MnO3·(1–x)LiMO2 electrodes. Surface modifications by thin coatings of Al2O3, V2O5, AlF3, AlPO4, etc. or by gas treatment (for instance, by NH3) can also enhance voltage and capacity stability during cycling. This paper describes the recent literature results and ongoing efforts from our groups to improve the performance of Li, Mn-rich materials. Focus is also on preparation of cobalt-free cathodes, which are integrated layered-spinel materials with high reversible capacity and stable performance.This review describes the recent literature results and ongoing efforts in the field to improve the performance of Li, Mn-rich materials as cathodes for Li-ion batteries. It is demonstrated that electrochemical performance of these cathodes can be improved by surface coatings, lattice doping, using surface active additives in the electrolyte solutions, controlling the activation process by temperature and voltage programming.
      PubDate: 2017-12-04T03:33:24.743118-05:
      DOI: 10.1002/aenm.201702397
  • Prescribing Functional Additives for Treating the Poor Performances of
           High-Voltage (5 V-class) LiNi0.5Mn1.5O4/MCMB Li-Ion Batteries
    • Authors: Gaojie Xu; Chunguang Pang, Bingbing Chen, Jun Ma, Xiao Wang, Jingchao Chai, Qingfu Wang, Weizhong An, Xinhong Zhou, Guanglei Cui, Liquan Chen
      Abstract: In this paper, tris(trimethylsilyl) phosphite (TMSP) and 1,3-propanediolcyclic sulfate (PCS) are unprecedentedly prescribed as binary functional additives for treating the poor performances of high-voltage (5 V-class) LiNi0.5Mn1.5O4/MCMB (graphitic mesocarbon microbeads) Li-ion batteries at both room temperature and 50 °C. The high-voltage LiNi0.5Mn1.5O4/MCMB cell with binary functional additives shows a preponderant discharge capacity retention of 79.5% after 500 cycles at 0.5 C rate at room temperature. By increasing the current intensity from 0.2 to 5 C rate, the discharge capacity retention of the high-voltage cell with binary functional additives is ≈90%, while the counterpart is only ≈55%. By characterizations, it is rationally demonstrated that the binary functional additives decompose and participate in the modification of solid–electrolyte interface layers (both electrodes), which are more conductive, protective, and resistant to electrolyte oxidative/reductive decompositions (accompanying active-Li+ consuming parasitic reactions) due to synergistic effects. Specifically, the TMSP additive can stabilize LiPF6 salt and scavenge erosive hydrofluoric acid. More encouragingly, at 50 °C, the high-voltage cell with binary functional additives holds an ultrahigh discharge capacity retention of 79.5% after 200 cycles at 1 C rate. Moreover, a third designed self-extinguishing flame-retardant additive of (ethoxy)-penta-fluoro-cyclo-triphosphazene (PFPN) is introduced for reducing the flammability of the aforementioned binary functional additives containing electrolyte.Here, the Chinese idiom “Xuan Hu Ji Shi” (Practise medicine in order to help the people) is used to express the willingness to save the earth home in peril by developing high energy/high power renewable-energy storage systems. Specifically, several functional additives are prescribed for electrolyte to greatly enhance the performances of a promising high-voltage (5 V-class) LiNi0.5Mn1.5O4/graphite battery system.
      PubDate: 2017-12-04T03:32:55.817678-05:
      DOI: 10.1002/aenm.201701398
  • Reverse Bias Behavior of Halide Perovskite Solar Cells
    • Authors: Andrea R. Bowring; Luca Bertoluzzi, Brian C. O'Regan, Michael D. McGehee
      Abstract: The future commercialization of halide perovskite solar cells relies on improving their stability. There are several studies focused on understanding degradation under operating conditions in light, but little is known about the stability of these solar cells under reverse bias conditions. Reverse bias stability is important because shaded cells in a module are put into reverse bias by the illuminated cells. In this paper, a phenomenological study is presented of the reverse bias behavior of halide perovskite solar cells and it is shown that reverse bias can lead to a partially recoverable loss in efficiency, primarily caused by a decrease in VOC. A general mechanism is proposed, supported by drift–diffusion simulations, to explain how these cells breakdown via tunneling caused by accumulated ionic defects and suggests that the reversible loss in efficiency may be due to an electrochemical reaction of these defects. Finally, the implications of these phenomena are discussed and how they can possibly be addressed is also discussed.The stability of halide perovskite solar cells in reverse bias is investigated. The cells uniformly pass current across the device at breakdown voltages between –1 and −4 V. A partially recoverable decrease in open-circuit voltage is seen for cells held in reverse bias. Drift–diffusion modeling supports breakdown via tunneling, and the implications and some possible solutions are discussed.
      PubDate: 2017-12-04T03:32:04.823035-05:
      DOI: 10.1002/aenm.201702365
  • Bimetallic Zeolitic Imidazolite Framework Derived Carbon Nanotubes
           Embedded with Co Nanoparticles for Efficient Bifunctional Oxygen
    • Authors: Yinle Li; Baoming Jia, Yanzhong Fan, Kelong Zhu, Guangqin Li, Cheng-Yong Su
      Abstract: Bifunctional oxygen catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with high activities and low-cost are of prime importance and challenging in the development of fuel cells and rechargeable metal–air batteries. This study reports a porous carbon nanomaterial loaded with cobalt nanoparticles (Co@NC-x/y) derived from pyrolysis of a Co/Zn bimetallic zeolitic imidazolite framework, which exhibits incredibly high activity as bifunctional oxygen catalysts. For instance, the optimal catalyst of Co@NC-3/1 has the interconnected framework structure between porous carbon and embedded carbon nanotubes, which shows the superb ORR activity with onset potential of ≈1.15 V and half-wave potential of ≈0.93 V. Moreover, it presents high OER activity that can be further enhanced to over commercial RuO2 by P-doped with overpotentials of 1.57 V versus reversible hydrogen electrode at 10 mA cm−2 and long-term stability for 2000 circles and a Tafel slope of 85 mV dec−1. Significantly, the nanomaterial demonstrates better catalytic performance and durability than Pt/C for ORR and commercial RuO2 and IrO2 for OER. These findings suggest the importance of a synergistic effect of graphitic carbon, nanotubes, exposed Co–Nx active sites, and interconnected framework structure of various carbons for bifunctional oxygen electrocatalysts.A porous carbon nanomaterial (Co@NC-x/y) embedded with cobalt nanoparticles and rooted with nanotubes derived from pyrolysis of a Co/Zn bimetallic zeolitic imidazolite framework is reported. The optimal catalyst of Co@NC-3/1 shows the superb oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities. And its mechanism is thoroughly discussed.
      PubDate: 2017-12-04T03:31:53.356301-05:
      DOI: 10.1002/aenm.201702048
  • Superior Oxygen Electrocatalysis on RuSex Nanoparticles for Rechargeable
           Air Cathodes
    • Authors: Ji-Hoon Jang; Eunjik Lee, Penghao Xiao, Kyusung Park, In Young Kim, Graeme Henkelman, Seong-Ju Hwang, Young-Uk Kwon, John. B. Goodenough
      Abstract: A one-step, facile supercritical-ethanol-fluid synthesis of Se-modified Ru nanoparticles nucleated on carbon defects is reported, and it is demonstrated that these nanoparticles provide, with >70% efficiency at 1 A g−1, a highly active and reversible oxygen-reduction/oxygen-evolution reaction on an air cathode in a nonaqueous electrolyte. The Se modification not only prevents Ru oxidation during charge/discharge cycling, but also improves the catalytic activity by promoting Li2O2 versus Li2O deposited on the Ru particles during discharge. A computational calculation with density functional theory supports the role of a larger electron transfer to the oxygen of Li2O2 adsorbed on a surface layer of RuSe2−δ than on a surface layer of RuO2, thereby shifting the more stable adsorbent from Li2O to Li2O2.As superior and durable electrocatalysts for rechargeable air cathode, carbon-supported RuSex nanoparticles (NPs) are prepared via a one-pot supercritical ethanol fluid process. Electrochemical characterization and computational calculation reveal that RuSex NPs enable to form amorphous and reversible Li2O2 as discharge, resulting in improved kinetics and cyclic stability in glyme-based electrolyte under the cell operation.
      PubDate: 2017-12-04T03:31:29.1048-05:00
      DOI: 10.1002/aenm.201702037
  • A Wireless Triboelectric Nanogenerator
    • Authors: Sai Sunil Kumar Mallineni; Yongchang Dong, Herbert Behlow, Apparao M. Rao, Ramakrishna Podila
      Abstract: A new “wireless” paradigm for harvesting mechanical energy via a 3D-printed wireless triboelectric nanogenerator (W-TENG) comprised of an ecofriendly graphene polylactic acid (gPLA) nanocomposite and Teflon is demonstrated. The W-TENG generates very high output voltages >2 kV with a strong electric field that enables the wireless transmission of harvested energy over a distance of 3 m. The W-TENG exhibited an instantaneous peak power up to 70 mW that could be wirelessly transmitted for storage into a capacitor obviating the need for hard-wiring or additional circuitry. Furthermore, the use of W-TENG for wireless and secure actuation of smart-home applications such as smart tint windows, temperature sensors, liquid crystal displays, and security alarms either with a single or a specific user-defined passcode of mechanical pulses (e.g., Fibonacci sequence) is demonstrated. The scalable additive manufacturing approach for gPLA-based W-TENGs, along with their high electrical output and unprecedented wireless applications, is poised for revolutionizing the present mechanical energy harvesting technologies.Self-powered triboelectric generation based wireless controller for smart home and security applications is 3D printed using graphene polylactic acid based nanocomposite. The wireless triboelectric nanogenerator is shown to generate over 2 kV of voltage when actuated by simple hand tap. The associated strong electric field in the vicinity is used to transmit wireless power up to 3 m range and control smart home applications and also charge energy storage devices.
      PubDate: 2017-12-04T03:23:05.860947-05:
      DOI: 10.1002/aenm.201702736
  • Recent Progress and Perspective in Electrode Materials for K-Ion Batteries
    • Authors: Haegyeom Kim; Jae Chul Kim, Matteo Bianchini, Dong-Hwa Seo, Jorge Rodriguez-Garcia, Gerbrand Ceder
      Abstract: The development of rechargeable batteries using K ions as charge carriers has recently attracted considerable attention in the search for cost-effective and large-scale energy storage systems. In light of this trend, various materials for positive and negative electrodes are proposed and evaluated for application in K-ion batteries. Here, a comprehensive review of ongoing materials research on nonaqueous K-ion batteries is offered. Information on the status of new materials discovery and insights to help understand the K-storage mechanisms are provided. In addition, strategies to enhance the electrochemical properties of K-ion batteries and computational approaches to better understand their thermodynamic properties are included. Finally, K-ion batteries are compared to competing Li and Na systems and pragmatic opportunities and future research directions are discussed.K-ion batteries are attracting much attention as an emerging energy storage system for large-scale applications. This review article provides the most up-to-date information on recent progress in the K-technology focusing on important negative and positive electrode materials. This article also discusses the science behind their electrochemistry and K storage mechanism.
      PubDate: 2017-12-04T03:21:34.069072-05:
      DOI: 10.1002/aenm.201702384
  • Broadband Enhancement of PbS Quantum Dot Solar Cells by the Synergistic
           Effect of Plasmonic Gold Nanobipyramids and Nanospheres
    • Authors: Si Chen; Yong jie Wang, Qipeng Liu, Guozheng Shi, Zeke Liu, Kunyuan Lu, Lu Han, Xufeng Ling, Han Zhang, Si Cheng, Wanli Ma
      Abstract: For the first time, the plasmonic gold bipyramids (Au BPs) are introduced to the PbS colloidal quantum dot (CQD) solar cells for improved infrared light harvesting. The localized surface plasmon resonance peaks of Au BPs matches perfectly with the absorption peaks of conventional PbS CQDs. Owing to the geometrical novelty of Au BPs, they exhibit significantly stronger far-field scattering effect and near-field enhancement than conventional plasmonic Au nanospheres (NSs). Consequently, device open-circuit voltage (Voc) and short-circuit current (Jsc) are simultaneously enhanced, while plasmonic photovoltaic devices based on Au NSs only achieve improved Jsc. The different effects and working mechanisms of these two Au nanoparticles are systematically investigated. Moreover, to realize effective broadband light harvesting, Au BPs and Au NSs are used together to simultaneously enhance the device optical and electrical properties. As a result, a significantly increased power conversion efficiency (PCE) of 9.58% is obtained compared to the PCE of 8.09% for the control devices due to the synergistic effect of the two plasmonic Au nanoparticles. Thus, this work reveals the intriguing plasmonic effect of Au BPs in CQD solar cells and may provide insight into the future plasmonic enhancement for solution-processed new-generation solar cells.For the first time, the plasmonic gold bipyramids (Au BPs) are introduced to the PbS colloidal quantum dots solar cells. To realize broadband light harvesting, Au BPs and Au nanospheres (NSs) are used together. As a result, a significantly increased power conversion efficiency (PCE) of 9.58% is obtained due to the synergistic effect of the two plasmonic Au nanoparticles.
      PubDate: 2017-12-04T03:20:51.249334-05:
      DOI: 10.1002/aenm.201701194
  • 3D Porous Carbon Sheets with Multidirectional Ion Pathways for Fast and
           Durable Lithium–Sulfur Batteries
    • Authors: Gaoran Li; Wen Lei, Dan Luo, Ya-Ping Deng, Deli Wang, Zhongwei Chen
      Abstract: In this work, unique porous carbon sheets (PCSs) are developed via a facile synthesis. The obtained PCS delivers long-range conductive framework, abundant active interfaces, rich element doping, and notably a high inner porosity that builds up an admirable 3D network for multidirectional ion transfer. Such unique architecture and surface chemistry enable ultrafast sulfur electrochemistry as well as high-efficiency inhibition on polysulfide shuttling via the dually physical and chemical sulfur confinement. The PCS-based sulfur electrodes achieve superb rate capability up to 10 C, outstanding cyclability over 1000 cycles, and high areal capacity of 4.8 mA h cm−2. This work offers an appealing model of material engineering for fast and reliable lithium–sulfur batteries, as well as guidance for rational structural design in extended energy storage and conversion systems.A unique porous carbon sheet (PCS) material is developed through a facile synthesis by using phosphorus pentoxide as a single template. When employed as advanced sulfur host for lithium–sulfur batteries, the as-developed PCS delivers multidirectional inner ion pathways and dually physical and chemical sulfur confinements, thus enabling admirably fast sulfur electrochemistry and excellent battery durability.
      PubDate: 2017-12-04T03:16:10.927494-05:
      DOI: 10.1002/aenm.201702381
  • Applications of Phosphorene and Black Phosphorus in Energy Conversion and
           Storage Devices
    • Authors: Jinbo Pang; Alicja Bachmatiuk, Yin Yin, Barbara Trzebicka, Liang Zhao, Lei Fu, Rafael G. Mendes, Thomas Gemming, Zhongfan Liu, Mark H. Rummeli
      Abstract: The successful isolation of phosphorene (atomic layer thick black phosphorus) in 2014 has currently aroused the interest of 2D material researchers. In this review, first, the fundamentals of phosphorus allotropes, phosphorene, and black phosphorus, are briefly introduced, along with their structures, properties, and synthesis methods. Second, the readers are presented with an overview of their energy applications. Particularly in electrochemical energy storage, the large interlayer spacing (0.53 nm) in phosphorene allows the intercalation/deintercalation of larger ions as compared to its graphene counterpart. Therefore, phosphorene may possess greater potential for high electrochemical performance. In addition, the status of lithium ion batteries as well as secondary sodium ion batteries is reviewed. Next, each application for energy generation, conversion, and storage is described in detail with milestones as well as the challenges. These emerging applications include supercapacitors, photovoltaic devices, water splitting, photocatalytic hydrogenation, oxygen evolution, and thermoelectric generators. Finally the fast-growing dynamic field of phosphorene research is summarized and perspectives on future possibilities are presented calling on the efforts of chemists, physicists, and material scientistsRecent advances of phosphorene production approaches have led to the great progress in its energy related applications. In this in-depth review, one can readily access the state of the art research on phosphorene. Examples include stability strategies, electrochemistry energy storage, and energy conversion.
      PubDate: 2017-12-01T04:03:11.797294-05:
      DOI: 10.1002/aenm.201702093
  • Unraveling Geometrical Site Confinement in Highly Efficient Iron-Doped
           Electrocatalysts toward Oxygen Evolution Reaction
    • Authors: Sung-Fu Hung; Ying-Ya Hsu, Chia-Jui Chang, Chia-Shuo Hsu, Nian-Tzu Suen, Ting-Shan Chan, Hao Ming Chen
      Abstract: Introduction of iron in various catalytic systems has served a crucial function to significantly enhance the catalytic activity toward oxygen evolution reaction (OER), but the relationship between material properties and catalysis is still elusive. In this study, by regulating the distinctive geometric sites in spinel, Fe occupies the octahedral sites (Fe3+(Oh)) and confines Co to the tetrahedral site (Co2+(Td)), resulting in a strikingly high activity (ηj = 10 mA cm−2 = 229 mV and ηj = 100 mA cm−2 = 281 mV). Further enrichment of Fe ions would occupy the tetrahedral sites to decline the amount of Co2+(Td) and deteriorate the OER activity. It is also found that similar tafel slope and peak frequency in Bode plot of electrochemical impedance spectroscopy indicate that Co2+(Td) ions are primarily in charge of water oxidation catalytic center. By means of electrochemical techniques and in situ X-ray absorption spectroscopy, it is proposed that Fe3+(Oh) ions mainly confine cobalt ions to the tetrahedral site to restrain the multipath transfer of cobalt ions during the dynamic structural transformation between spinel and oxyhydroxide, continuously activating the catalytic behavior of Co2+(Td) ions. This material-related insight provides an indication for the design of highly efficient OER electrocatalysts.Iron doping in geometrical octahedral sites would significantly enhance the catalytic ability toward oxygen evolution reaction. Geometrical-site confinement of iron ions leads to the cobalt ions in tetrahedral sites continuously activated under an activation process, achieving a strikingly high activity (ηj = 10 mA cm−2 = 229 mV and ηj = 100 mA cm−2 = 281 mV).
      PubDate: 2017-11-30T06:06:42.004125-05:
      DOI: 10.1002/aenm.201701686
  • Superelastic Hybrid CNT/Graphene Fibers for Wearable Energy Storage
    • Authors: Zan Lu; Javad Foroughi, Caiyun Wang, Hairu Long, Gordon G. Wallace
      Abstract: The demands for wearable technologies continue to grow and novel approaches for powering these devices are being enabled by the advent of new electromaterials and novel fabrication strategies. Herein, a novel approach is reported to develop superelastic wet-spun hybrid carbon nanotube graphene fibers followed by electrodeposition of polyaniline to achieve a high-performance fiber-based supercapacitor. It is found that the specific capacitance of hybrid carbon nanotube (CNT)/graphene fiber is enhanced up to ≈39% using a graphene to CNT fiber ratio of 1:3. Fabrication of spring-like coiled fiber coated with an elastic polymer shows an extraordinary elasticity capable of 800% strain while affording a specific capacitance of ≈138 F g−1. The elastic rubber coating enables extreme stretchability and enabling cycles with up to 500% strain for thousands of cycles with no significant change in its performance. Multiple supercapacitors can be easily assembled in series or parallel to meet specific energy and power needs.A novel approach to develop superelastic wet-spun hybrid carbon nanotube graphene fibers is demonstrated. Fabrication of spring-like coiled fiber coated with an elastic polymer shows an extraordinary elasticity capable of 800% strain while affording a specific capacitance of ≈138 F g−1. The developed processing method is scalable for the fabrication of industrial quantities of wearable technology (Smart Textiles).
      PubDate: 2017-11-29T03:37:05.466926-05:
      DOI: 10.1002/aenm.201702047
  • Carbon-Sheathed MoS2 Nanothorns Epitaxially Grown on CNTs: Electrochemical
           Application for Highly Stable and Ultrafast Lithium Storage
    • Authors: Zijia Zhang; Hailei Zhao, Yongqiang Teng, Xiwang Chang, Qing Xia, Zhaolin Li, Jiejun Fang, Zhihong Du, Konrad Świerczek
      Abstract: Molybdenum disulfide (MoS2), which possesses a layered structure and exhibits a high theoretical capacity, is currently under intensive research as an anode candidate for next generation of Li-ion batteries. However, unmodified MoS2 suffers from a poor cycling stability and an inferior rate capability upon charge/discharge processes. Herein, a unique nanocomposite comprising MoS2 nanothorns epitaxially grown on the backbone of carbon nanotubes (CNTs) and coated by a layer of amorphous carbon is synthesized via a simple method. The epitaxial growth of MoS2 on CNTs results in a strong chemical coupling between active nanothorns and carbon substrate via CS bond, providing a high stability as well as a high-efficiency electron-conduction/ion-transportation system on cycling. The outer carbon layer can well-accommodate the structural strain in the electrode upon lithium-ion insertion/extraction. When employed as an anode for lithium storage, the prepared material exhibits remarkable electrochemical properties with a high specific capacity of 982 mA h g−1 at 0.1 A g−1, as well as excellent long-cycling stability (905 mA h g−1 at 1 A g−1 after 500 cycles) and superior rate capability, confirming its potential application in high-performance Li-ion batteries.Carbon-sheathed MoS2 nanothorns epitaxially grown on carbon nanotubes (CNTs) are prepared as a high-stable and ultrafast lithium storage material. The epitaxial growth provides strong adhesion between MoS2 and CNTs via chemical CS bond, ensuring not only a high stability but also a high-efficiency electron-conduction/ion-transportation system on cycling. The prepared electrode exhibits high specific capacity, superior rate capability, and excellent long-cycling stability.
      PubDate: 2017-11-28T03:47:02.749493-05:
      DOI: 10.1002/aenm.201700174
  • Vertically Aligned MoS2 Nanosheets Patterned on Electrochemically
           Exfoliated Graphene for High-Performance Lithium and Sodium Storage
    • Authors: Gang Wang; Jian Zhang, Sheng Yang, Faxing Wang, Xiaodong Zhuang, Klaus Müllen, Xinliang Feng
      Abstract: Molybdenum disulfide (MoS2) has been recognized as a promising anode material for high-energy Li-ion (LIBs) and Na-ion batteries (SIBs) due to its apparently high capacity and intriguing 2D-layered structure. The low conductivity, unsatisfied mechanical stability, and limited active material utilization are three key challenges associated with MoS2 electrodes especially at high current rates and mass active material loading. Here, vertical MoS2 nanosheets are controllably patterned onto electrochemically exfoliated graphene (EG). Within the achieved hierarchical architecture, the intimate contact between EG and MoS2 nanosheets, interconnected network, and effective exposure of active materials by vertical channels simultaneously overcomes the above three problems, enabling high mechanical integrity and fast charge transport kinetics. Serving as anode material for LIBs, EG-MoS2 with 95 wt% MoS2 content delivered an ultrahigh-specific capacity of 1250 mA h g−1 after 150 stable cycles at 1 A g−1, which is among the highest values in all reported MoS2 electrodes, and excellent rate performance (970 mA h g−1 at 5 A g−1). Moreover, impressive cycling stability (509 mA h g−1 at 1 A g−1 after 250 cycles) and rate capability (423 mA h g−1 at 2 A g−1) were also achieved for SIBs. The area capacities reached 1.27 and 0.49 mA h cm−2 at ≈1 mA cm−2 for LIBs and SIBs, respectively. This work may inspire the development of new 2D hierarchical structures for high efficiency energy storage and conversion.Vertically aligned molybdenum disulfide (MoS2) nanosheets are controllably patterned on electrochemically exfoliated graphene, resulting in 2D graphene-MoS2 hybrids. Due to the excellent mechanical stability, effective exposure of active materials and fast charge transport kinetics, the resultant 2D graphene-MoS2 delivers ultrahigh-specific capacities, impressive cycling stability, and rate capability for both Li-ion batteries and Na-ion batteries.
      PubDate: 2017-11-28T03:42:23.358794-05:
      DOI: 10.1002/aenm.201702254
  • Inverted Design for High-Performance Supercapacitor Via Co(OH)2-Derived
           Highly Oriented MOF Electrodes
    • Authors: Ting Deng; Yue Lu, Wei Zhang, Manling Sui, Xiaoyuan Shi, Dong Wang, Weitao Zheng
      Abstract: Metal organic frameworks (MOFs) are considered as promising candidates for supercapacitors because of high specific area and potential redox sites. However, their shuffled orientations and low conductivity nature lead to severely-degraded performance. Designing an accessibly-manipulated and efficient method to address those issues is of outmost significance for MOF application in supercapacitors. It is the common way that MOFs scarify themselves as templates or precursors to prepare target products. But to reversely think it, using target products to prepare MOF could be the way to unlock the bottleneck of MOFs' performance in supercapacitors. Herein, a novel strategy using Co(OH)2 as both the template and precursor to fabricate vertically-oriented MOF electrode is proposed. The electrode shows a double high specific capacitance of 1044 Fg−1 and excellent rate capability compared to MOF in powder form. An asymmetric supercapacitor was also fabricated, which delivers a maximum energy density of 28.5 W h kg−1 at a power density of 1500 W kg−1, and the maximum of 24000 W kg−1 can be obtained with a remaining energy density of 13.3 W h kg−1. Therefore, the proposed strategy paves the way to unlock the inherent advantages of MOFs and also inspires for advanced MOF synthesis with optimum performance.A novel reverse strategy to design integrated metal organic framework (MOF) electrode is proposed for supercapacitors by using vertically oriented Co(OH)2 as both the template and precursor to prepare MOF with highly uniform orientation. The reverse design enables properly addressing the low conductivity and random orientation issues of MOF. And the assembled hybrid capacitors can deliver a maximum energy density of 28.5 W h kg−1 and a maximum power density of 24 000 W kg−1.
      PubDate: 2017-11-27T07:39:00.253426-05:
      DOI: 10.1002/aenm.201702294
  • Hierarchical Zn–Co–S Nanowires as Advanced Electrodes for All Solid
           State Asymmetric Supercapacitors
    • Authors: Chao Li; Jayaraman Balamurugan, Nam Hoon Kim, Joong Hee Lee
      Abstract: A facile two-step strategy is developed to design the large-scale synthesis of hierarchical, unique porous architecture of ternary metal hydroxide nanowires grown on porous 3D Ni foam and subsequent effective sulfurization. The hierarchical Zn–Co–S nanowires (NWs) arrays are directly employed as an electrode for supercapacitors application. The as-synthesized Zn–Co–S NWs deliver an ultrahigh areal capacity of 0.9 mA h cm−2 (specific capacity of 366.7 mA h g−1) at a current density of 3 mA cm−2, with an exceptional rate capability (≈227.6 mA h g−1 at a very high current density of 40 mA cm−2) and outstanding cycling stability (≈93.2% of capacity retention after 10 000 cycles). Most significantly, the assembled Zn–Co–S NWs//Fe2O3@reduced graphene oxide asymmetric supercapacitors with a wide operating potential window of ≈1.6 V yield an ultrahigh volumetric capacity of ≈1.98 mA h cm−3 at a current density of 3 mA cm−2, excellent energy density of ≈81.6 W h kg−1 at a power density of ≈559.2 W kg−1, and exceptional cycling performance (≈92.1% of capacity retention after 10 000 cycles). This general strategy provides an alternative to design the other ternary metal sulfides, making it facile, free-standing, binder-free, and cost-effective ternary metal sulfide-based electrodes for large-scale applications in modern electronics.The present work demonstrates the construction of hierarchical Zn–Co–S nanowires (NWs) for high performance all solid state asymmetric supercapacitors. The Zn–Co–S NWs//Fe2O3@reduced graphene oxide asymmetric supercapacitor delivers an excellent energy density of ≈81.6 W h kg−1 at a power density of ≈559.2 W kg−1, and exceptional cycling performance (≈92.1% capacity retention after 10 000 cycles).
      PubDate: 2017-11-27T07:38:35.526578-05:
      DOI: 10.1002/aenm.201702014
  • Quantifying the Role of Nanotubes in Nano:Nano Composite Supercapacitor
    • Authors: Zheng Ling; Andrew Harvey, David McAteer, Ian J. Godwin, Beata Szydłowska, Aideen Griffin, Victor Vega, Yongchen Song, Andrés Seral-Ascaso, Valeria Nicolosi, Jonathan Coleman
      Abstract: Many promising supercapacitor electrode materials have high resistivity and require conductive additives to function effectively. However, the detailed role of the additive is not understood. Here, this question is resolved by applying a quantitative model for resistance-limited supercapacitor electrodes to Co(OH)2-nanosheet/carbon nanotube composites. Without nanotubes, theory predicts and experiments show that while the low-rate capacitance increases linearly with electrode thickness, the high rate capacitance decreases with thickness due to slow charging. Experiments supported by theory show that nanotube addition has two effects. First, the nanotube network effectively distributes charge, increasing the intrinsic electrode performance to the limit associated with its accessible surface area. Second, at high-rate, the increased electrode conductivity shifts the rate-limiting resistance from electrode to electrolyte, thus removing the thickness-dependent capacitance falloff. Furthermore, the analysis quantifies the out-of-plane conductivity of the nanotube network, identifies the cross-over from resistance-limited to diffusion-limited behavior, and allows full electrode modeling, facilitating rational design.Combining models for electrically limited capacitance with data for Co(OH)2-SWNT composite supercapacitor electrodes leads to a fuller understanding of limitations of low-conductivity electrode materials and the role of nanotubes in resolving them. The resultant insights allow the development of an analytical model describing capacitance as a function of scan-rate, electrode thickness, and nanotube content.
      PubDate: 2017-11-27T07:37:20.588833-05:
      DOI: 10.1002/aenm.201702364
  • High-Performance and Uniform 1 cm2 Polymer Solar Cells with D1-A-D2-A-Type
           Random Terpolymers
    • Authors: Injeong Shin; Hyung ju Ahn, Jae Hoon Yun, Jea Woong Jo, Sungmin Park, Sung-yoon Joe, Joona Bang, Hae Jung Son
      Abstract: For the commercial development of organic photovoltaics (OPVs), laboratory-scale OPV technology must be translated to large area modules. In particular, it is important to develop high-efficiency polymers that can form thick (>100 nm) bulk heterojunction (BHJ) films over large areas with optimal morphologies for charge generation and transport. Here, D1-A-D2-A random terpolymers composed of 2,2′-bithiophene with various proportions of 5,6-difluoro-4,7-bis(thiophen-2-yl)-2,1,3-benzothiadiazole and 5,6-difluoro-2,1,3-benzothiadiazole (FBT) are synthesized. It is found that incorporating small proportions of FBT into the polymer not only conserves the high crystallinity and favorable face-on orientation of the D-A copolymer FBT-Th4 but also improves the nanoscale phase separation of the BHJ film. Consequently, the random terpolymer PDT2fBT-BT10 exhibits a much improved solar cell efficiency of 10.31% when compared to that of the copolymer FBT-Th4 (8.62%). Moreover, due to this polymer's excellent processability and suppressed overaggregation, OPVs with 1 cm2 active area based on 351 nm thick PDT2fBT-BT10 BHJs exhibit high photovoltaic performance of 9.42%, whereas rapid efficiency decreases arise for FBT-Th4-based OPVs for film thicknesses above 300 nm. It is demonstrated that this random terpolymer can be used in large area and thick BHJ OPVs, and guidelines for developing polymers that are suitable for large-scale printing technologies are presented.D1-A-D2-A-type random terpolymers and organic photovoltaics (OPVs) are developed introducing that the resulting polymer achieves a high efficiency of 10.31%. Furthermore, reproducibility of 1 cm2 OPVs shows a high efficiency up to 9.42% using thick active layers in the range of 250–380 nm.
      PubDate: 2017-11-27T07:36:43.011913-05:
      DOI: 10.1002/aenm.201701405
  • Amorphous Tin-Based Composite Oxide: A High-Rate and Ultralong-Life
           Sodium-Ion-Storage Material
    • Authors: Xu Yang; Rong-Yu Zhang, Jing Zhao, Zhi-Xuan Wei, Dong-Xue Wang, Xiao-Fei Bie, Yu Gao, Jia Wang, Fei Du, Gang Chen
      Abstract: Energy-storage technology is moving beyond lithium batteries to sodium as a result of its high abundance and low cost. However, this sensible transition requires the discovery of high-rate and long-lifespan anode materials, which remains a significant challenge. Here, the facile synthesis of an amorphous Sn2P2O7/reduced graphene oxide nanocomposite and its sodium storage performance between 0.01 and 3.0 V are reported for the first time. This hybrid electrode delivers a high specific capacity of 480 mA h g−1 at a current density of 50 mA g−1 and superior rate performance of 250 and 165 mA h g−1 at 2 and 10 A g−1, respectively. Strikingly, this anode can sustain 15 000 cycles while retaining over 70% of the initial capacity. Quantitative kinetic analysis reveals that the sodium storage is governed by pseudocapacitance, particularly at high current rates. A full cell with sodium super ionic conductor (NASICON)-structured Na3V2(PO4)2F3 and Na3V2(PO4)3 as cathodes exhibits a high energy density of over 140 W h kg−1 and a power density of nearly 9000 W kg−1 as well as stability over 1000 cycles. This exceptional performance suggests that the present system is a promising power source for promoting the substantial use of low-cost energy storage systems.The illustration of amorphous tin-based composite oxide (ATCO) as a high-performance anode for a sodium ion battery is shown with a high rate of performance of 180 mA h g−1 at current of 2 A g−1 for 15 000 cycles. Quantitative kinetic analysis reveals that the sodium storage is governed by pseudocapacitance, particularly at high current rates.
      PubDate: 2017-11-27T07:36:16.432626-05:
      DOI: 10.1002/aenm.201701827
  • Selenium Impregnated Monolithic Carbons as Free-Standing Cathodes for High
           Volumetric Energy Lithium and Sodium Metal Batteries
    • Authors: Jia Ding; Hui Zhou, Hanlei Zhang, Linyue Tong, David Mitlin
      Abstract: Energy density (energy per volume) is a key consideration for portable, automotive, and stationary battery applications. Selenium (Se) lithium and sodium metal cathodes are created that are monolithic and free-standing, and with record Se loading of 70 wt%. The carbon host is derived from nanocellulose, an abundant and sustainable forestry product. The composite is extremely dense (2.37 g cm−3), enabling theoretical volumetric capacity of 1120 mA h cm−3. Such architecture is fully distinct from previous Se–carbon nano- or micropowders, intrinsically offering up to 2× higher energy density. For Li storage, the cathode delivers reversible capacity of 1028 mA h cm−3 (620 mA h g−1) and 82% retention over 300 cycles. For Na storage, 848 mA h cm−3 (511 mA h g−1) is obtained with 98% retention after 150 cycles. The electrodes yield superb volumetric energy densities, being 1727 W h L−1 for Li–Se and 980 W h L−1 for Na–Se normalized by total composite mass and volume. Despite the low surface area, over 60% capacity is maintained as the current density is increased from 0.1 to 2 C (30 min charge) with Li or Na. Remarkably, the electrochemical kinetics with Li and Na are comparable, including the transition from interfacial to diffusional control.A method is devised to double the energy of Se–Li and Se–Na batteries, by creating dense monolithic electrodes with a carbonized cellulose host melt impregnated by Se. The cells yield remarkable performance: 1028 mA h cm−3 (620 mA h g−1) with 82% retention over 300 cycles with Li, and 848 mA h cm−3 (511 mA h g−1) with 98% retention at 150 cycles with Na.
      PubDate: 2017-11-27T07:35:46.923898-05:
      DOI: 10.1002/aenm.201701918
  • High and Reversible Lithium Ion Storage in Self-Exfoliated
           Triazole-Triformyl Phloroglucinol-Based Covalent Organic Nanosheets
    • Authors: Sattwick Haldar; Kingshuk Roy, Shyamapada Nandi, Debanjan Chakraborty, Dhanya Puthusseri, Yogesh Gawli, Satishchandra Ogale, Ramanathan Vaidhyanathan
      Abstract: Covalent organic framework (COF) can grow into self-exfoliated nanosheets. Their graphene/graphite resembling microtexture and nanostructure suits electrochemical applications. Here, covalent organic nanosheets (CON) with nanopores lined with triazole and phloroglucinol units, neither of which binds lithium strongly, and its potential as an anode in Li-ion battery are presented. Their fibrous texture enables facile amalgamation as a coin-cell anode, which exhibits exceptionally high specific capacity of ≈720 mA h g−1 (@100 mA g−1). Its capacity is retained even after 1000 cycles. Increasing the current density from 100 mA g−1 to 1 A g−1 causes the specific capacity to drop only by 20%, which is the lowest among all high-performing anodic COFs. The majority of the lithium insertion follows an ultrafast diffusion-controlled intercalation (diffusion coefficient, DLi+ = 5.48 × 10−11 cm2 s−1). The absence of strong Li-framework bonds in the density functional theory (DFT) optimized structure supports this reversible intercalation. The discrete monomer of the CON shows a specific capacity of only 140 mA h g−1 @50 mA g−1 and no sign of lithium intercalation reveals the crucial role played by the polymeric structure of the CON in this intercalation-assisted conductivity. The potentials mapped using DFT suggest a substantial electronic driving-force for the lithium intercalation. The findings underscore the potential of the designer CON as anode material for Li-ion batteries.Self-exfoliated triazole-triformyl phloroglucinol-based covalent organic nanosheets with high and reversible lithium ion storage capacity as anodes in Li-ion battery. It shows exceptional stability across a wide current density window and retains 100% columbic efficiency across 1000 cycles.
      PubDate: 2017-11-24T06:56:49.063892-05:
      DOI: 10.1002/aenm.201702170
  • Design and Performance of Rechargeable Sodium Ion Batteries, and
           Symmetrical Li-Ion Batteries with Supercapacitor-Like Power Density Based
           upon Polyoxovanadates
    • Authors: Jia-Jia Chen; Jian-Chuan Ye, Xia-Guang Zhang, Mark D. Symes, Shao-Cong Fan, De-Liang Long, Ming-Sen Zheng, De-Yin Wu, Leroy Cronin, Quan-Feng Dong
      Abstract: The polyanion Li7V15O36(CO3) is a nanosized molecular cluster (≈1 nm in size), that has the potential to form an open host framework with a higher surface-to-bulk ratio than conventional transition metal oxide electrode materials. Herein, practical rechargeable Na-ion batteries and symmetric Li-ion batteries are demonstrated based on the polyoxovanadate Li7V15O36(CO3). The vanadium centers in {V15O36(CO3)} do not all have the same VIV/V redox potentials, which permits symmetric devices to be created from this material that exhibit battery-like energy density and supercapacitor-like power density. An ultrahigh specific power of 51.5 kW kg−1 at 100 A g−1 and a specific energy of 125 W h kg−1 can be achieved, along with a long cycling life (>500 cycles). Moreover, electrochemical and theoretical studies reveal that {V15O36(CO3)} also allows the transport of large cations, like Na+, and that it can serve as the cathode material for rechargeable Na-ion batteries with a high specific capacity of 240 mA h g−1 and a specific energy of 390 W h kg−1 for the full Na-ion battery. Finally, the polyoxometalate material from these electrochemical energy storage devices can be easily extracted from spent electrodes by simple treatment with water, providing a potential route to recycling of the redox active material.A Li7V15O36(CO3)-cluster-based Li-ion device exhibits battery-like energy density of 125 W h kg−1 and supercapacitor-like power density of 51.5 kW kg−1 at 100 A g−1, along with a long cycling life (>500 cycles). Moreover, it also permits fast diffusion of large cations, like Na+, and shows a high energy density (390 W h kg−1) as the cathode in full Na-ion batteries.
      PubDate: 2017-11-22T11:06:18.424433-05:
      DOI: 10.1002/aenm.201701021
  • Flexible and Semitransparent Organic Solar Cells
    • Authors: Yaowen Li; Guiying Xu, Chaohua Cui, Yongfang Li
      Abstract: Flexible and semitransparent organic solar cells (OSCs) have been regarded as the most promising photovoltaic devices for the application of OSCs in wearable energy resources and building-integrated photovoltaics. Therefore, the flexible and semitransparent OSCs have developed rapidly in recent years through the synergistic efforts in developing novel flexible bottom or top transparent electrodes, designing and synthesizing high performance photoactive layer and low temperature processed electrode buffer layer materials, and device architecture engineering. To date, the highest power conversion efficiencies have reached over 10% of the flexible OSCs and 7.7% with average visible transmittance of 37% for the semitransparent OSCs. Here, a comprehensive overview of recent research progresses and perspectives on the related materials and devices of the flexible and semitransparent OSCs is provided.Flexible and semitransparent organic solar cells (OSCs) are regarded as the most promising photovoltaic devices for the application of OSCs in wearable energy resources and building-integrated photovoltaics. Here, a comprehensive overview of recent research progresses and perspectives on the related materials and devices of the flexible and semitransparent OSCs is provided.
      PubDate: 2017-11-22T10:59:20.775295-05:
      DOI: 10.1002/aenm.201701791
  • Layered Oxide Cathodes for Sodium-Ion Batteries: Phase Transition, Air
           Stability, and Performance
    • Authors: Peng-Fei Wang; Ya You, Ya-Xia Yin, Yu-Guo Guo
      Abstract: The increasing demand for replacing conventional fossil fuels with clean energy or economical and sustainable energy storage drives better battery research today. Sodium-ion batteries (SIBs) are considered as a promising alternative for grid-scale storage applications due to their similar “rocking-chair” sodium storage mechanism to lithium-ion batteries, the natural abundance, and the low cost of Na resources. Searching for appropriate electrode materials with acceptable electrochemical performance is the key point for development of SIBs. Layered transition metal oxides represent one of the most fascinating electrode materials owing to their superior specific capacity, environmental benignity, and facile synthesis. However, three major challenges (irreversible phase transition, storage instability, and insufficient battery performance) are known for cathodes in SIBs. Herein, a comprehensive review on the latest advances and progresses in the exploration of layered oxides for SIBs is presented, and a detailed and deep understanding of the relationship of phase transition, air stability, and electrochemical performance in layered oxide cathodes is provided in terms of refining the structure–function–property relationship to design improved battery materials. Layered oxides will be a competitive and attractive choice as cathodes for SIBs in next-generation energy storage devices.The recent progress in layered oxide cathodes for sodium-ion batteries is comprehensively reviewed. Some new perspectives concentrating on phase transition, air stability, and electrochemical performance in layered cathodes are provided, in terms of refining the structure–function–property relationship to rationally design better electrode materials.
      PubDate: 2017-11-22T10:58:04.985536-05:
      DOI: 10.1002/aenm.201701912
  • Masthead: (Adv. Energy Mater. 22/2017)
    • PubDate: 2017-11-22T06:22:26.385767-05:
      DOI: 10.1002/aenm.201770127
  • Perovskite Solar Cells: Efficient Perovskite Solar Cells over a Broad
           Temperature Window: The Role of the Charge Carrier Extraction (Adv. Energy
           Mater. 22/2017)
    • Authors: Shuyan Shao; Jian Liu, Hong-Hua Fang, Li Qiu, Gert H. ten Brink, Jan C. Hummelen, L. Jan Anton Koster, Maria Antonietta Loi
      Abstract: In article number 1701305, Maria Antonietta Loi and co-workers show that the electron transport capability of the electron-extracting layer dominates the temperature dependence of the performance of hybrid perovskite solar cells. The authors further demonstrate efficient hybrid perovskite solar cells over a temperature range from 295 K to 160 K by n-doping the PCBM electron-extracting layer or using a fullerene derivative with intrinsically higher electron transport capability.
      PubDate: 2017-11-22T06:22:23.984153-05:
      DOI: 10.1002/aenm.201770133
  • Photocatalysis: Design and Fabrication of a Precious Metal-Free Tandem
           Core–Shell p+n Si/W-Doped BiVO4 Photoanode for Unassisted Water
           Splitting (Adv. Energy Mater. 22/2017)
    • Authors: Pongkarn Chakthranont; Thomas R. Hellstern, Joshua M. McEnaney, Thomas F. Jaramillo
      Abstract: Tandem photoelectrochemical water splitting cells utilizing crystalline Si and metal oxide photoabsorbers are promising for low-cost solar hydrogen production. In article number 1701515, Thomas F. Jaramillo and co-workers present a device design and a scalable fabrication scheme for a tandem heterostructure photoanode: p+n black silicon (Si)/SnO2 interface/W-doped bismuth vanadate (BiVO4)/cobalt phosphate (CoPi) catalyst.
      PubDate: 2017-11-22T06:22:23.51262-05:0
      DOI: 10.1002/aenm.201770131
  • Solar Water Splitting: Enhancing Charge Carrier Lifetime in Metal Oxide
           Photoelectrodes through Mild Hydrogen Treatment (Adv. Energy Mater.
    • Authors: Ji-Wook Jang; Dennis Friedrich, Sönke Müller, Marlene Lamers, Hannes Hempel, Sheikha Lardhi, Zhen Cao, Moussab Harb, Luigi Cavallo, René Heller, Rainer Eichberger, Roel van de Krol, Fatwa F. Abdi
      Abstract: Time-resolved conductivity measurements reveal that a mild hydrogen treatment at 300 °C for 10 minutes successfully extends the lifetime of carriers by more than two-fold in bismuth vanadate (BiVO4) photoelectrodes. This enhancement is a result of passivation of deep trap states and/or reduction of their density. Consequently, the AM1.5 photocurrent and onset potential for the hydrogen-treated BiVO4 are significantly improved. This is reported by Fatwa F. Abdi and co-workers in article number 1701536.
      PubDate: 2017-11-22T06:22:22.728116-05:
      DOI: 10.1002/aenm.201770132
  • Lithium Batteries: NiS2/FeS Holey Film as Freestanding Electrode for
           High-Performance Lithium Battery (Adv. Energy Mater. 22/2017)
    • Authors: Kun Liang; Kyle Marcus, Shoufeng Zhang, Le Zhou, Yilun Li, Samuel T. De Oliveira, Nina Orlovskaya, Yong-Ho Sohn, Yang Yang
      Abstract: The fabrication of a freestanding NiS2/FeS holey film by electrochemically anodic and thermal treatments is reported by Yang Yang and co-workers in article number 1701309. With the combination of good electrical conductivity and porous structure, the NiS2/FeS holey film presents superior electrochemical performance towards lithium storage. This work opens a new paradigm for high energy and long-lifetime lithium batteries.
      PubDate: 2017-11-22T06:22:21.456501-05:
      DOI: 10.1002/aenm.201770129
  • Co2 Reduction: Selective Etching of Nitrogen-Doped Carbon by Steam for
           Enhanced Electrochemical CO2 Reduction (Adv. Energy Mater. 22/2017)
    • Authors: Xiaoqi Cui; Zhiyong Pan, Lijuan Zhang, Huisheng Peng, Gengfeng Zheng
      Abstract: In article number 1701456, Gengfeng Zheng and co-workers develop a steam-etching approach to tune the configurations of nitrogen dopants in carbon frameworks. The nitrogen-doped (“orange atoms”) graphitic carbon surface (“grey atoms”) mimics a planet, and the water droplets strike the “planet” like comets, mimicking the steam-etching step. CO2 bubbles connected with nitrogen atoms by lightning indicate the CO2 electrochemical reduction.
      PubDate: 2017-11-22T06:22:19.532875-05:
      DOI: 10.1002/aenm.201770126
  • Lithium-Ion Batteries: Flexible Composite Solid Electrolyte Facilitating
           Highly Stable “Soft Contacting” Li–Electrolyte Interface for Solid
           State Lithium-Ion Batteries (Adv. Energy Mater. 22/2017)
    • Authors: Luyi Yang; Zijian Wang, Yancong Feng, Rui Tan, Yunxing Zuo, Rongtan Gao, Yan Zhao, Lei Han, Ziqi Wang, Feng Pan
      Abstract: In article number 1701437, a flexible composite solid electrolyte membrane consisting of polymer and Li-ion conductive ceramic is prepared and investigated by Feng Pan and co-workers. The addition of boronized poly ethylene glycol (BPEG) oligomer not only improves its ionic conductivity, but also facilitates a better contact between the lithium metal and the electrolyte, resulting a smooth lithium interface after cycling.
      PubDate: 2017-11-22T06:22:17.962961-05:
      DOI: 10.1002/aenm.201770130
  • Contents: (Adv. Energy Mater. 22/2017)
    • PubDate: 2017-11-22T06:22:16.866596-05:
      DOI: 10.1002/aenm.201770128
  • Lithium-Ion Batteries: All-Nanomat Lithium-Ion Batteries: A New Cell
           Architecture Platform for Ultrahigh Energy Density and Mechanical
           Flexibility (Adv. Energy Mater. 22/2017)
    • Authors: Ju-Myung Kim; Jeong A. Kim, Seung-Hyeok Kim, In Sung Uhm, Sung Joong Kang, Guntae Kim, Sun-Young Lee, Sun-Hwa Yeon, Sang-Young Lee
      Abstract: All-nanomat (Si anode/Al2O3 separator/OLO cathode) LIB full cells based on 1D building elements-interweaved heteronanomat skeletons are presented as a simple and versatile platform technology for advanced power sources by Sang-Young Lee and co-workers in article number 1701099. The well-tailored heteronanomat cell architecture allows for formation of 3D-bicontinuous ion/electron transport pathways and elimination of metallic foil current collectors, resulting in exceptional improvements in the energy density and in mechanical deformability which lie far beyond those achievable with conventional LIB technologies.
      PubDate: 2017-11-22T06:22:16.811861-05:
      DOI: 10.1002/aenm.201770125
  • Feasible D1–A–D2–A Random Copolymers for Simultaneous
           High-Performance Fullerene and Nonfullerene Solar Cells
    • Authors: Mingyu Jeong; Shanshan Chen, Sang Myeon Lee, Zhiwei Wang, Yankang Yang, Zhi-Guo Zhang, Chunfeng Zhang, Min Xiao, Yongfang Li, Changduk Yang
      Abstract: A series of PBDB-TTn random donor copolymers is synthesized, consisting of an electron-deficient benzo[1,2-c:4,5-c′]dithiophene-4,8-dione (BDD) unit and different ratios of two electron-rich benzo[1,2-b:4,5-b′]dithiophene (BDT) and thieno[3,2-b]thiophene (TT) units, with intention to modulate the intrachain and/or interchain interactions and ultimately bulk-heterojunction morphology evolution. A comparative study using 4 × 2 polymer solar cell (PSC) performance maps and each of the [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) and the fused-aromatic-ring-based molecule (m-ITIC) acceptors are carried out. Given the similarities in their absorption ranges and energy levels, the PBDB-TTn copolymers clearly reveal a change in the absorption coefficients upon optimization of the BDT to TT ratio in the backbone. Among the given acceptor combination sets, superior performances are observed in the case of PBDB-TT5 blended with PC71BM (8.34 ± 0.10%) or m-ITIC (11.10 ± 0.08%), and the dominant factors causing power conversion efficiency differences in them are found to be distinctly different. For example, the performances of PC71BM-based PSCs are governed by size and population of face-on crystallites, while intermixed morphology without the formation of large phase-separated aggregates is the key factor for achieving high-performance m-ITIC-based PSCs. This study presents a new sketch of structure–morphology–performance relationships for fullerene- versus nonfullerene-based PSCs.BDD-based four copolymers PBDD-TTn which contained BDT, TT, and BDD are synthesized and operated with two acceptors, PC71BM and m-ITIC. Two systems have different operating mechanisms, and simultaneously high-performances 8.44% for PC71BM and 11.18% for m-ITIC are obtained.
      PubDate: 2017-11-16T09:27:47.506139-05:
      DOI: 10.1002/aenm.201702166
  • Recent Developments on and Prospects for Electrode Materials with
           Hierarchical Structures for Lithium-Ion Batteries
    • Authors: Limin Zhou; Kai Zhang, Zhe Hu, Zhanliang Tao, Liqiang Mai, Yong-Mook Kang, Shu-Lei Chou, Jun Chen
      Abstract: Since their successful commercialization in 1990s, lithium-ion batteries (LIBs) have been widely applied in portable digital products. The energy density and power density of LIBs are inadequate, however, to satisfy the continuous growth in demand. Considering the cost distribution in battery system, it is essential to explore cathode/anode materials with excellent rate capability and long cycle life. Nanometer-sized electrode materials could quickly take up and store numerous Li+ ions, afforded by short diffusion channels and large surface area. Unfortunately, low thermodynamic stability of nanoparticles results in electrochemical agglomeration and raises the risk of side reactions on electrolyte. Thus, micro/nano and hetero/hierarchical structures, characterized by ordered assembly of different sizes, phases, and/or pores, have been developed, which enable us to effectively improve the utilization, reaction kinetics, and structural stability of electrode materials. This review summarizes the recent efforts on electrode materials with hierarchical structures, and discusses the effects of hierarchical structures on electrochemical performance in detail. Multidimensional self-assembled structures can achieve integration of the advantages of materials with different sizes. Core/yolk–shell structures provide synergistic effects between the shell and the core/yolk. Porous structures with macro-, meso-, and micropores can accommodate volume expansion and facilitate electrolyte infiltration.Recent developments on electrode materials with hierarchical structure are summarized and the effects of hierarchical structures on electrochemical performance are discussed. To deal with the intrinsic defects of the materials themselves, several common structures are proposed to address the problems of cathode and anode materials, such as multidimensional self-assembled structures, core/yolk–shell structures, and porous structures.
      PubDate: 2017-11-16T09:27:05.099402-05:
      DOI: 10.1002/aenm.201701415
  • Gel Polymer Electrolytes for Electrochemical Energy Storage
    • Authors: Xunliang Cheng; Jian Pan, Yang Zhao, Meng Liao, Huisheng Peng
      Abstract: With the booming development of flexible and wearable electronics, their safety issues and operation stabilities have attracted worldwide attentions. Compared with traditional liquid electrolytes, gel polymer electrolytes (GPEs) are preferred due to their higher safety and adaptability to the design of flexible energy storage devices. This review summarizes the recent progress of GPEs with enhanced physicochemical properties and specified functionalities for the application in electrochemical energy storage. Functional GPEs that are capable to achieve unity lithium-ion transference number and offer additional pseudocapacitance to the overall capacitance are carefully discussed. The smart GPEs with self-protection, thermotolerant, and self-healing abilities are particularly highlighted. To close, the future directions and remaining challenges of the GPEs for application in electrochemical energy storages are summarized to provide clues for the following development.Gel polymer electrolytes represent an attractive alternative to liquid electrolytes due to the superiorities of higher safety, better flexibility, and higher workability, which are promising for the use in electrochemical energy storage for the next-generation flexible and wearable electronics. Their recent advancements, challenges, and perspectives are highlighted to provide guidance for the future study.
      PubDate: 2017-11-16T09:26:12.010075-05:
      DOI: 10.1002/aenm.201702184
  • Uniform Pomegranate-Like Nanoclusters Organized by Ultrafine Transition
           Metal Oxide@Nitrogen-Doped Carbon Subunits with Enhanced Lithium Storage
    • Authors: Bingqiu Liu; Qi Zhang, Zhanshuang Jin, Lingyu Zhang, Lu Li, Zhigang Gao, Chungang Wang, Haiming Xie, Zhongmin Su
      Abstract: Uniform pomegranate-like nanoclusters (NCs) organized by ultrafine transition metal oxide@nitrogen-doped carbon (TMO@N–C) subunits (diameter ≈ 4 nm) are prepared on a large scale for the first time through a facile, novel, and one-pot approach. Taking pomegranate-like Fe3O4@N–C NCs as an example, this unique structure provides short Li+/electron diffusion pathways for electrochemical reactions, structural stability during cycling, and high electrical conductivity, leading to superior electrochemical performance. The resulting pomegranate-like Fe3O4@N–C NCs possess a high specific capacity (1204.3 mA h g−1 at 0.5 A g−1 over 100 cycles), a stable cycle life (1063.0 mA h g−1 at 1 A g−1, 98.4% retention after 1000 cycles), and excellent rate capacities (606.0 mA h g−1 at 10 A g−1, 92.0% retention; 417.1 mA h g−1 at 20 A g−1, 91.7% retention after 1000 cycles).A facile and novel one-pot approach is prepared for the first time to synthesize a series of highly uniform pomegranate-like transition metal oxide@nitrogen-doped carbon (TMO@N–C) nanoclusters with a large scale production, which are organized by numerous of ultrafine TMO@N–C subunits (diameter ≈ 4 nm). Such unique nanostructure exhibits high specific capacity, excellent rate performance, and superior cycling stability.
      PubDate: 2017-11-09T12:41:09.901148-05:
      DOI: 10.1002/aenm.201702347
  • Long Cycle Life, Low Self-Discharge Sodium–Selenium Batteries with High
           Selenium Loading and Suppressed Polyselenide Shuttling
    • Authors: Hui Wang; Yang Jiang, Arumugam Manthiram
      Abstract: The use of selenium as a cathode in rechargeable sodium–selenium batteries is hampered by low Se loading, inferior electrode kinetics, and polyselenide shuttling between the cathode and anode. Here a high-performance sodium–selenium cell is presented by coupling a binder-free, self-interwoven carbon nanofiber–selenium cathode with a light-weight carbon-coated bifunctional separator. With this strategy, electrodes with a high Se mass loading (4.4 mg cm−2) render high reversible capacities of 599 mA h g−1 at 0.1C rate and 382 mA h g−1 at 5C rate. In addition, this novel cell offers good shelf-life with a low self-discharge, retaining 93.4% of its initial capacity even after resting for six months. As evidenced by experimental and density functional theory analysis, the remarkable dynamic (cycle life) and static (shelf-life) stabilities originate from the high electrical conductivity, improved Na-ion accessibility through the 3D interconnected open channels, and highly restrained polyselenide shuttle. The results demonstrate the viability of high-performance sodium–selenium batteries with high selenium loading.A novel NaSe cell, assembled by coupling self-interwoven carbon nanofiber/Se with a carbon-coated separator displays excellent cycling life stability with a high selenium loading of 4.4 mg cm−2. The cell also retains 93.4% of its initial capacity even after resting for six months, making the NaSe cells competitive for energy storage.
      PubDate: 2017-11-08T09:32:17.973638-05:
      DOI: 10.1002/aenm.201701953
  • A Shockley-Type Polymer: Fullerene Solar Cell
    • Authors: Ardalan Armin; Zhiming Chen, Yaocheng Jin, Kai Zhang, Fei Huang, Safa Shoaee
      Abstract: Charge extraction rate in solar cells made of blends of electron donating/accepting organic semiconductors is typically slow due to their low charge carrier mobility. This sets a limit on the active layer thickness and has hindered the industrialization of organic solar cells (OSCs). Herein, charge transport and recombination properties of an efficient polymer (NT812):fullerene blend are investigated. This system delivers power conversion efficiency of >9% even when the junction thickness is as large as 800 nm. Experimental results indicate that this material system exhibits exceptionally low bimolecular recombination constant, 800 times smaller than the diffusion-controlled electron and hole encounter rate. Comparing theoretical results based on a recently introduced modified Shockley model for fill factor, and experiments, clarifies that charge collection is nearly ideal in these solar cells even when the thickness is several hundreds of nanometer. This is the first realization of high-efficiency Shockley-type organic solar cells with junction thicknesses suitable for scaling up.Strongly suppressed recombination is observed in a polymer:fullerene system resulting in solar cell power conversion efficiencies as high as 9% at a junction thickness of 800 nm. Results indicate that solar cell devices made of this material system with thicknesses as large as 300 nm can exhibit Shockley-type behavior, i.e., the fill factor is unaffected by bimolecular recombination.
      PubDate: 2017-11-08T02:35:38.297898-05:
      DOI: 10.1002/aenm.201701450
  • Charge and Discharge Processes and Sodium Storage in Disodium
           Pyridine-2,5-Dicarboxylate Anode—Insights from Experiments and Theory
    • Authors: Harihara Padhy; Yingqian Chen, Johann Lüder, Satyanarayana Reddy Gajella, Sergei Manzhos, Palani Balaya
      Abstract: A combined experimental and computational study of disodium pyridine-2,5-dicarboxylate (Na2PDC) is presented exploring the possibility of using it as a potential anode for organic sodium-ion batteries. This electrode material can reversibly insert/release two Na cations per formula unit, resulting in high reversible capacity of 270 mA h g−1 (236 mA h g−1 after accounting for the contribution from Super P carbon) with excellent cyclability 225 mA h g−1, with retention of 83% capacity after 100 cycles, and good rate performance with reversible capacity of 138 mA h g−1 at a 5 C rate. The performance of disodium pyridine dicarboxylate is therefore found to be superior to that of the related and well investigated disodium terephthalate. The material shows two voltage plateaus at about 0.6 V up to Na2+1PDC and then 0.4 V up to full sodiation, Na2+2PDC. The first plateau is attributed to the coordination of inserted Na to nitrogen atoms with bond formation, i.e., a different mechanism from the terephthalate analog. The subsequent plateau is due to coordination to the carboxylic groups.The disodium pyridine-2,5-dicarboxylate anode-based Na-ion batteries perform good cyclability and rate performance with a high reversible capacity of 270 mA h g−1. A higher voltage of ≈0.6 V achieved compared with disodium terephthalate, which is confirmed by the computational analysis. The sodiation mechanism is also verified by the good agreement between experimental and computational X-ray diffraction patterns.
      PubDate: 2017-11-08T01:21:23.279559-05:
      DOI: 10.1002/aenm.201701572
  • Prospect and Reality of Ni-Rich Cathode for Commercialization
    • Authors: Junhyeok Kim; Hyomyung Lee, Hyungyeon Cha, Moonsu Yoon, Minjoon Park, Jaephil Cho
      Abstract: The layered nickel-rich cathode materials are considered as promising cathode materials for lithium-ion batteries (LIBs) due to their high reversible capacity and low cost. However, several significant challenges, such as the unstable powder properties and limited electrode density, hindered the practical application of the nickel-rich cathode materials with the nickel content over 80%. Herein, important stability issues and in-depth understanding of the nickel-rich cathode materials on the basis of the industrial electrode fabrication condition for the commercialization of the nickel-rich cathode materials are reviewed. A variety of factors threatening the battery safety such as the powder properties, thermal/structural stability are systemically investigated from a material point of view. Furthermore, recent efforts for enhancing the electrochemical stability of the nickel-rich cathode materials are summarized. More importantly, critical key parameters that should be considered for the high energy LIBs at an electrode level are intensively addressed for the first time. Current electrode fabrication condition has a difficulty in increasing the energy density of the battery. Finally, light is shed on the perspectives for the future research direction of the nickel-rich cathode materials with its technical challenges in current state by the practical aspect.Nickel-rich cathode material is a most appealing cathode material owing to its high reversible capacity for high-energy lithium-ion batteries. In this review, the recent research progress in the nickel-rich cathode materials is summarized. Moreover, the key challenges for the industrial application of the nickel-rich cathode and its future research perspective are provided.
      PubDate: 2017-11-07T11:39:38.708413-05:
      DOI: 10.1002/aenm.201702028
  • High Performance Thermoelectric Materials: Progress and Their Applications
    • Authors: Lei Yang; Zhi-Gang Chen, Matthew S. Dargusch, Jin Zou
      Abstract: Thermoelectric (TE) materials have the capability of converting heat into electricity, which can improve fuel efficiency, as well as providing robust alternative energy supply in multiple applications by collecting wasted heat, and therefore, assisting in finding new energy solutions. In order to construct high performance TE devices, superior TE materials have to be targeted via various strategies. The development of high performance TE devices can broaden the market of TE application and eventually boost the enthusiasm of TE material research. This review focuses on major novel strategies to achieve high-performance TE materials and their applications. Manipulating the carrier concentration and band structures of materials are effective in optimizing the electrical transport properties, while nanostructure engineering and defect engineering can greatly reduce the thermal conductivity approaching the amorphous limit. Currently, TE devices are utilized to generate power in remote missions, solar–thermal systems, implantable or/wearable devices, the automotive industry, and many other fields; they are also serving as temperature sensors and controllers or even gas sensors. The future tendency is to synergistically optimize and integrate all the effective factors to further improve the TE performance, so that highly efficient TE materials and devices can be more beneficial to daily lives.The goal of current studies of thermoelectric materials is to identify novel thermoelectric materials and to enhance their performance by applying appropriate strategies, which targets on manipulating individual effective factors or synergistically optimizing the overall performance, broadens the device application of thermoelectric materials, and boosts the market growth.
      PubDate: 2017-11-07T11:37:51.570644-05:
      DOI: 10.1002/aenm.201701797
  • Rational Assembly of Hollow Microporous Carbon Spheres as P Hosts for
           Long-Life Sodium-Ion Batteries
    • Authors: Shanshan Yao; Jiang Cui, Jiaqiang Huang, Jian-Qiu Huang, Woon Gie Chong, Lei Qin, Yiu-Wing Mai, Jang-Kyo Kim
      Abstract: This paper reports the rational assembly of novel hollow porous carbon nanospheres (HPCNSs) as the hosts of phosphorous (P) active materials for high-performance sodium-ion batteries (SIBs). The vaporization-condensation process is employed to synthesize P/C composites, which is elucidated by both theories and experiments to achieve optimized designs. The combined molecular dynamics simulations and density functional theory calculations indicate that the morphologies of polymeric P4 and the P loading in the P/C composites depend mainly on the pore size and surface condition of carbon supports. Micropores of 1–2 nm in diameter and oxygenated functional groups attached on carbon surface are essential for achieving high P loading and excellent structural stability. In light of these findings, HPCNS/amorphous red phosphorus composites with enhanced structural/functional features are synthesized, which present an extremely low volume expansion of ≈67.3% during cycles, much smaller than the commercial red P's theoretical value of ≈300%. The composite anodes deliver an exceptional sodium storage capacity and remarkable long-life cyclic stability with capacity retention over 76% after 1000 cycles. This work signifies the importance of rational design of electrode materials based on accurate theoretical predictions and sheds light on future development of cost-effective P/C composite anodes for commercially viable SIBs.For the first time, the mechanisms of P adsorption process are elucidated by combining molecular dynamics simulations and density functional theory calculations. Inspired by the new discoveries, precisely controlled synthesis of hollow microporous carbon nanosphere/red phosphorus composites are achieved as anodes for sodium-ion batteries, which illustrate exceptional mechanical stability upon sodiation/desodiation revealed by in situ transmission electron microscope.
      PubDate: 2017-11-07T11:36:50.031681-05:
      DOI: 10.1002/aenm.201702267
  • Interface Engineering for Highly Efficient and Stable Planar p-i-n
           Perovskite Solar Cells
    • Authors: Yang Bai; Xiangyue Meng, Shihe Yang
      Abstract: Organic-inorganic halide perovskite materials have become a shining star in the photovoltaic field due to their unique properties, such as high absorption coefficient, optimal bandgap, and high defect tolerance, which also lead to the breathtaking increase in power conversion efficiency from 3.8% to over 22% in just seven years. Although the highest efficiency was obtained from the TiO2 mesoporous structure, there are increasing studies focusing on the planar structure device due to its processibility for large-scale production. In particular, the planar p-i-n structure has attracted increasing attention on account of its tremendous advantages in, among other things, eliminating hysteresis alongside a competitive certified efficiency of over 20%. Crucial for the device performance enhancement has been the interface engineering for the past few years, especially for such planar p-i-n devices. The interface engineering aims to optimize device properties, such as charge transfer, defect passivation, band alignment, etc. Herein, recent progress on the interface engineering of planar p-i-n structure devices is reviewed. This review is mainly focused on the interface design between each layer in p-i-n structure devices, as well as grain boundaries, which are the interfaces between polycrystalline perovskite domains. Promising research directions are also suggested for further improvements.Interface engineering has been widely practiced on planar p-i-n perovskite solar cells since it brings about significant improvement in both device performance and stability. Recent progress is reviewed about the engineering of each interface of such devices and its effects, including defect passivation, accelerated charge transfer, enhanced stabilities, etc., which are key parameters for the photovoltaic devices.
      PubDate: 2017-11-07T11:35:53.103818-05:
      DOI: 10.1002/aenm.201701883
  • Macroporous Catalytic Carbon Nanotemplates for Sodium Metal Anodes
    • Authors: Hyeon Ji Yoon; Na Rae Kim, Hyoung-Joon Jin, Young Soo Yun
      Abstract: Because of its remarkably high theoretical capacity and favorable redox voltage (−2.71 V vs the standard hydrogen electrode), Na is a promising anode material for Na ion batteries. In this study, macroporous catalytic carbon nanotemplates (MC-CNTs) based on nanoweb-structured carbon nanofibers with various carbon microstructures are prepared from microbe-derived cellulose via simple heating at 800 or 2400 °C. MC-CNTs prepared at 800 °C have amorphous carbon structures with numerous topological defects, and exhibit a lower voltage overpotential of ≈8 mV in galvanostatic charge/discharge testing. In addition, MC-CNT-800s exhibit high Coulombic efficiencies of 99.4–99.9% during consecutive cycling at current densities ranging from 0.2 to 4 mA cm−2. However, the carbon structures of MC-CNTs prepared at 800 °C are gradually damaged by cycling. This results in significant capacity losses after about 200 cycles. In contrast, MC-CNTs prepared at 2400 °C exhibit well-developed graphitic structures, and maintain predominantly stable cycling behaviors over 1000 cycles with Coulombic efficiencies of ≈99.9%. This study demonstrates the superiority of catalytic carbon nanotemplates with well-defined pore structures and graphitic microstructures for use in Na metal anodes.Macroporous catalytic carbon nanotemplates (MC-CNTs) with different graphitic microstructures are fabricated from microbe-derived cellulose by a simple heating process from 800 to 2400 °C. MC-CNTs exhibit a remarkably small overpotential than Al foil electrode and excellent Coulombic efficiency of 99.9% at 1 mA cm−2 (1 A g−1). However, MC-CNTs show distinct cycling performance depending on graphitization degree.
      PubDate: 2017-11-07T11:30:41.250854-05:
      DOI: 10.1002/aenm.201701261
  • Flexible and Stretchable Biobatteries: Monolithic Integration of
           Membrane-Free Microbial Fuel Cells in a Single Textile Layer
    • Authors: Sumiao Pang; Yang Gao, Seokheun Choi
      Abstract: The fabrication and performance of a flexible and stretchable microbial fuel cell (MFC) monolithically integrated into a single sheet of textile substrate are reported. The single-layer textile MFC uses Pseudomonas aeruginosa (PAO1) as a biocatalyst to produce a maximum power of 6.4 µW cm−2 and current density of 52 µA cm−2, which are substantially higher than previous textile-MFCs and are similar to other flexible paper-based MFCs. The textile MFC demonstrates a stable performance with repeated stretching and twisting cycles. The membrane-less single-chamber configuration drastically simplifies the fabrication and improves the performance of the MFC. A conductive and hydrophilic anode in a 3D fabric microchamber maximizes bacterial electricity generation from a liquid environment and a silver oxide/silver solid-state cathode reduces cathodic overpotential for fast catalytic reaction. A simple batch fabrication approach simultaneously constructs 35 individual devices, which will revolutionize the mass production of textile MFCs. This stretchable and twistable power device printed directly onto a single textile substrate can establish a standardized platform for textile-based biobatteries and will be potentially integrated into wearable electronics in the future.A flexible and stretchable microbial fuel cell (MFC) is monolithically integrated into a single sheet of textile substrate. The device uses electricity-producing bacteria to produce a maximum power of 6.4 µW cm−2 and current density of 52 µA cm−2 and demonstrates a stable performance with repeated stretching and twisting cycles. The membrane-less single-chamber configuration simplifies the fabrication and improves the performance of the MFC.
      PubDate: 2017-11-06T04:33:47.654888-05:
      DOI: 10.1002/aenm.201702261
  • Alkaline Fuel Cells with Novel Gortex-Based Electrodes are Powered
           Remarkably Efficiently by Methane Containing 5% Hydrogen
    • Authors: Klaudia Wagner; Prerna Tiwari, Gerhard F. Swiegers, Gordon G. Wallace
      Abstract: Numerous electric and gas utilities are actively pursuing “power-to-gas” technology, which involves using unwanted, excess renewable energy to manufacture hydrogen gas (H2) that is then injected into the existing natural gas pipeline network in 5–10% by volume. This work reports an alkaline fuel cell that has the potential to harness such gas mixtures for downstream generation of electric power. The fuel cell, which employs novel Gortex-based electrodes layered with Pd/Pt catalysts, generates electricity remarkably efficiently when fuelled with methane (CH4) containing 5% hydrogen. Methane constitutes the major component of natural gas. The fuel cell has been studied over a range of hydrogen to methane ratios using Tafel plots and electrochemical impedance spectroscopy. These show that, in terms of fundamental operation, there is, astonishingly, almost no difference between using pure hydrogen and 5% hydrogen in methane, as the fuel. The Gortex electrodes and alkaline electrolyte are clearly able to utilize the dilute hydrogen as a fuel with remarkable efficiency. The methane acts as an inert carrier gas and is not consumed.Numerous electric and gas utilities are pursuing “Power-to-Gas” (P2G) technology, which involves converting excess renewable power to hydrogen that is injected into the natural gas network in 5–10% by volume. Here, an alkaline fuel cell is reported that may potentially harness such mixtures to generate electrical power. The fuel cell sustainably generates electricity when fuelled with 5% H2 in methane.
      PubDate: 2017-10-26T03:50:54.859607-05:
      DOI: 10.1002/aenm.201702285
  • Utilizing Waste Cable Wires for High-Performance Fiber-Based Hybrid
           Supercapacitors: An Effective Approach to Electronic-Waste Management
    • Authors: Goli Nagaraju; S. Chandra Sekhar, Jae Su Yu
      Abstract: In recent years, electronic waste (e-waste) such as old cable wires, fans, circuit boards, etc., can be often seen in large piles of leftover in dumping yards. Employing these e-waste sources for energy storage devices not only increases the economic value but also decreases the reliance on fossil fuels. In this context, waste cable wires are utilized to obtain precious copper (Cu) fibers and used as a cost-effective current collector for the fabrication of fiber-based hybrid supercapacitor (FHSC). With the braided Cu fibers, forest-like nickel oxide nanosheet grafted carbon nanotube coupled copper oxide nanowire arrays (NiO NSs@CNTs@CuO NWAs/Cu fibers) are designed via simple wet-chemical approaches. As a battery-type material, the forest-like NiO NSs@CNTs@CuO NWAs/Cu fiber electrode shows superior electrochemical properties including high specific capacity (230.48 mA h g−1) and cycling stability (82.72%) in aqueous alkaline electrolyte. Moreover, a solid-state FHSC is also fabricated using forest-like NiO NSs@CNTs@CuO NWAs/Cu fibers as a positive electrode and activated carbon coated carbon fibers as a negative electrode with a gel electrolyte, which also shows a higher energy and power densities of 26.32 W h kg−1 and 1218.33 W kg−1, respectively. The flexible FHSC is further employed as an energy source for various electronic gadgets, demonstrating its suitability for wearable applications.A cost-effective fiber-based hybrid supercapacitor is fabricated using waste cable wires. The forest-like composite nanostructures coated on copper fibers serve as a positive electrode with superior electro­­chemical performance. Such rationally designed nanoarchitectures prepared on flexible and fiber-based electrodes provide a step forward for the development of wearable energy storage devices with improved energy storage performance.
      PubDate: 2017-10-25T10:11:29.208489-05:
      DOI: 10.1002/aenm.201702201
  • Reducing Mg Anode Overpotential via Ion Conductive Surface Layer Formation
           by Iodine Additive
    • Authors: Xiaogang Li; Tao Gao, Fudong Han, Zhaohui Ma, Xiulin Fan, Singyuk Hou, Nico Eidson, Weishan Li, Chunsheng Wang
      Abstract: Electrolytes that are able to reversibly deposit/strip Mg are crucial for rechargeable Mg batteries. The most studied complex electrolytes based on Lewis acid-base chemistry are expensive, difficult to be synthesized, and show limited anodic stability. Conventional electrolytes using simple salts such as Mg(TFSI)2 can be readily synthesized, but Mg deposition/stripping in these simple salt electrolytes is accompanied by a large overpotential due to the formation of a surface layer on the Mg metal with a low Mg ion conductivity. Here the overpotential for Mg deposition/stripping in a simple salt, Mg(TFSI)2-1,2-dimethoxyethane (DME), electrolyte is significantly reduced by adding a small concentration of iodine (≤50 × 10−3m) as an additive. Mechanism studies demonstrate that an Mg ion conductive solid MgI2 layer is formed on the surface of the Mg metal and acts as a solid electrolyte interface. With the Mg(TFSI)2-DME-I2 electrolyte, a very small voltage hysteresis is achieved in an Mg-S full cell.A solid electrolyte interphase (SEI) layer is formed due to the reaction of iodine with Mg, whose main component is magnesium iodide. This SEI layer dramatically decreases the overpotential of Mg deposition/stripping, hence enabling the usage of simple electrolyte Mg(TFSI)2-1,2-dimethoxyethane (DME) in full cells. For the first time, the SEI concept is successfully used in Mg batteries to address the interfacial kinetics problem.
      PubDate: 2017-10-24T11:41:19.064596-05:
      DOI: 10.1002/aenm.201701728
  • Solar-to-Hydrogen Energy Conversion Based on Water Splitting
    • Authors: Jing Qi; Wei Zhang, Rui Cao
      Abstract: Artificial photosynthesis provides a blueprint to harvest solar energy to sustain the future energy demands. Solar-driven water splitting, converting solar energy into hydrogen energy, is the prototype of photosynthesis. Various systems have been designed and evaluated to understand the reaction pathways and/or to meet the requirements of potential applications. In solar-to-hydrogen conversion, electrocatalytic hydrogen and oxygen evolution reactions are key research areas that are meaningful both theoretically and practically. To utilize hydrogen energy, fuel cell technology has been extensively investigated because of its high efficiency in releasing chemical energy. In this review, general concepts of the photosynthesis in green plants are discussed, different strategies for the light-driven water splitting proposed in laboratories are introduced, the progress of electrocatalytic hydrogen and oxygen evolution reactions are reviewed, and finally, the reactions in hydrogen fuel cells are briefly discussed. Overall, the mass and energy circulation in the solar-hydrogen-electricity circle are delineated. The authors conclude that attention from scientists and engineers of relevant research areas is still highly needed to eliminate the wide disparity between the aspirations and realities of artificial photosynthesis.The mass and energy circulation in the solar-hydrogen-electricity circle is delineated herein. The general concepts of natural photosynthesis in green plants, the different strategies of light-driven water splitting proposed in laboratories, the progress of electrocatalytic hydrogen evolution reaction and the oxygen evolution reaction, and the electrode reactions in hydrogen fuel cells are discussed.
      PubDate: 2017-10-23T08:15:54.343981-05:
      DOI: 10.1002/aenm.201701620
  • Nitrogen-Doped Porous Molybdenum Carbide and Phosphide Hybrids on a Carbon
           Matrix as Highly Effective Electrocatalysts for the Hydrogen Evolution
    • Authors: Yichao Huang; Jingxuan Ge, Jun Hu, Jiangwei Zhang, Jian Hao, Yongge Wei
      Abstract: The efficient evolution of hydrogen through electrocatalysis is considered a promising approach to the production of clean hydrogen fuel. Platinum (Pt)-based materials are regarded as the most active hydrogen evolution reaction (HER) catalysts. However, the low abundance and high cost of Pt hinders the large-scale application of these catalysts. Active, inexpensive, and earth-abundant electrocatalysts to replace Pt-based materials would be highly beneficial to the production of cost-effective hydrogen energy. Herein, a novel organoimido-derivatized heteropolyoxometalate, Mo4-CNP, is designed as a precursor for electrocatalysts of the HER. It is demonstrated that the carbon, nitrogen, and phosphorus sources derived from the Mo4-CNP molecules lead to in situ confined carburization, phosphorization, and chemical doping on an atomic scale, thus forming nitrogen-doped porous molybdenum carbide and phosphide hybrids, which exhibit remarkable electrocatalytic activity for the HER. Such an organically functionalized polyoxometalate-assisted strategy described here provides a new perspective for the development of highly active non-noble metal electrocatalysts for hydrogen evolution.A novel organoimido-derivatized heteropolyoxometalate, Mo4-CNP, is designed as a precursor for hydrogen evolution reaction (HER) electrocatalysts. It is demonstrated that the carbon, nitrogen, and phosphorous sources derived from the Mo4-CNP molecules lead to in situ and confined carburization, phosphorization, and chemical doping on the atomic scale, forming nitrogen-doped porous molybdenum carbide and phosphide hybrids with remarkable electrocatalytic HER activity.
      PubDate: 2017-10-17T07:34:41.443695-05:
      DOI: 10.1002/aenm.201701601
  • Efficient Solar Cells Based on Light-Harvesting Antimony Sulfoiodide
    • Authors: Riming Nie; Hyun-sung Yun, Min-Jae Paik, Aarti Mehta, Byung-wook Park, Yong Chan Choi, Sang Il Seok
      Abstract: Although antimony sulfoiodide (SbSI) exhibits very interesting properties including high photoconductivity, ferroelectricity, and piezoelectricity, it is not applied to solar cells. Meanwhile, SbSI is predominantly prepared as a powder using a high-temperature, high-pressure system. Herein, the fabrication of solar cells utilizing SbSI as light harvesters is reported for the first time to the best of knowledge. SbSI is prepared by solution processing, followed by annealing under mild temperature conditions by a reaction between antimony trisulfide, which is deposited by chemical bath deposition on a mesoporous TiO2 electrode and antimony triiodide, under air at a low temperature (90 °C) without any external pressure. The solar cells fabricated using SbSI exhibit a power conversion efficiency of 3.05% under standard illumination conditions of 100 mW cm−2.Solar cells with the configuration of FTO (fluorine-doped SnO2)/TiO2 blocking layer/mesoporous TiO2/SbSI/hole-transporting material/Au are demonstrated for the first time. The cells fabricated using TiO2 as an electron-transporting layer and poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] as a hole-transporting layer exhibit a power conversion efficiency of 3.05% under full illumination of air mass 1.5G.
      PubDate: 2017-10-16T08:06:26.450301-05:
      DOI: 10.1002/aenm.201701901
  • Atomic-Scale Monitoring of Electrode Materials in Lithium-Ion Batteries
           using In Situ Transmission Electron Microscopy
    • Authors: Tongtong Shang; Yuren Wen, Dongdong Xiao, Lin Gu, Yong-Sheng Hu, Hong Li
      Abstract: Lithium-ion batteries (LIBs) are energy storage devices that have received much attention because of their high energy density, high power capacity, and long lifetime. However, even though they are used widely in daily life, their cycling life and safety need further improvement. Understanding the reaction mechanisms and the structural degradation during the lithiation/delithiation process is a prerequisite to further improve the performance of LIBs. In situ transmission electron microscopy (TEM) allows one to monitor structural evolution at the atomic scale in real time, thus providing an unprecedented opportunity to characterize the lithiation reaction pathway in a nonequilibrium state during battery cycling. In this article, the recent advances with respect to elucidating the relationships of dynamic structural evolution, reaction kinetics, and performance of different nanostructured electrode materials at the atomic scale using in situ TEM, based on three representative reaction mechanisms, are described. Specifically, the three systems are intercalation reaction, conversion reaction, and alloying reaction. Based on the advances that have been made, it is expected that in situ TEM will play an indispensable role on future design of LIBs electrode materials.Based on the relationships among structure evolution, reaction kinetics and performance, understanding the electrochemical reaction mechanism of electrode materials provides guidelines for improving performance and designing electrode materials of LIBs. This article summarizes recent progresses towards unraveling the atomic-scale structure evolution of different electrode materials using in situ TEM with three electrochemical reaction mechanisms: intercalation, conversion and alloying reactions
      PubDate: 2017-10-16T08:02:39.228514-05:
      DOI: 10.1002/aenm.201700709
  • p-Type CuI Islands on TiO2 Electron Transport Layer for a Highly Efficient
           Planar-Perovskite Solar Cell with Negligible Hysteresis
    • Authors: Mahdi Malekshahi Byranvand; Taewan Kim, Seulki Song, Gyeongho Kang, Seung Un Ryu, Taiho Park
      Abstract: Compact TiO2 is widely used as an electron transport material in planar-perovskite solar cells. However, TiO2-based planar-perovskite solar cells exhibit low efficiencies due to intrinsic problems such as the unsuitable conduction band energy and low electron extraction ability of TiO2. Herein, the planar TiO2 electron transport layer (ETL) of perovskite solar cells is modified with ionic salt CuI via a simple one-step spin-coating process. The p-type nature of the CuI islands on the TiO2 surface leads to modification of the TiO2 band alignment, resulting in barrier-free contacts and increased open-circuit voltage. It is found that the polarity of the CuI-modified TiO2 surface can pull electrons to the interface between the perovskite and the TiO2, which improves electron extraction and reduces nonradiative recombination. The CuI solution concentration is varied to control the electron extraction of the modified TiO2 ETL, and the optimized device shows a high efficiency of 19.0%. In addition, the optimized device shows negligible hysteresis, which is believed to be due to the removal of trap sites and effective electron extraction by CuI-modified TiO2. These results demonstrate the hitherto unknown effect of p-type ionic salts on electron transport material.It is revealed that the CuI islands on the TiO2 electron transport layer can induce change of polarity increasing electron extraction, establish barrier-free band alignment with perovskite, and reduce the trap sites. These changes of interface properties induce power conversion efficiency of 19.0% perovskite solar cell with negligible hysteresis.
      PubDate: 2017-10-16T08:01:47.481769-05:
      DOI: 10.1002/aenm.201702235
  • High-Efficiency Low-Temperature ZnO Based Perovskite Solar Cells Based on
           Highly Polar, Nonwetting Self-Assembled Molecular Layers
    • Authors: Randi Azmi; Wisnu Tantyo Hadmojo, Septy Sinaga, Chang-Lyoul Lee, Sung Cheol Yoon, In Hwan Jung, Sung-Yeon Jang
      Abstract: Herein, this study reports high-efficiency, low-temperature ZnO based planar perovskite solar cells (PSCs) with state-of-the-art performance. They are achieved via a strategy that combines dual-functional self-assembled monolayer (SAM) modification of ZnO electron accepting layers (EALs) with sequential deposition of perovskite active layers. The SAMs, constructed from newly synthesized molecules with high dipole moments, act both as excellent surface wetting control layers and as electric dipole layers for ZnO-EALs. The insertion of SAMs improves the quality of PbI2 layers and final perovskite layers during sequential deposition, while charge extraction is enhanced via electric dipole effects. Leveraged by SAM modification, our low-temperature ZnO based PSCs achieve an unprecedentedly high power conversion efficiency of 18.82% with a VOC of 1.13 V, a JSC of 21.72 mA cm−2, and a FF of 0.76. The strategy used in this study can be further developed to produce additional performance enhancements or fabrication temperature reductions.Low-temperature planar perovskite solar cells with efficiency of 18.82% are developed via a strategy that combines dual-functional self-assembled monolayer (SAM) modification of ZnO electron accepting layers with sequential deposition of perovskite active layers. The SAMs, constructed from newly synthesized molecules with high dipole moments, act both as excellent surface wetting control layers and as electric dipole layers for ZnO layers.
      PubDate: 2017-10-16T08:00:42.376612-05:
      DOI: 10.1002/aenm.201701683
  • Intrinsic Nanodomains in Triplite LiFeSO4F and Its Implication in
           Lithium-Ion Diffusion
    • Authors: Dong-Hwa Seo; Kyu-Young Park, Haegyeom Kim, Sung-Kyun Jung, Min-Sik Park, Kisuk Kang
      Abstract: Triplite-type LiFeSO4F has attracted considerable attention as a promising cathode for next-generation lithium-ion batteries because of its high redox potential based on earth-abundant Fe2+/3+. However, successful extraction/reinsertion of all the lithium ions in triplite host is challenging even at a low current rate, resulting in a low specific capacity. These experimental findings contrast with previous theoretical works that predicted that the triplite structure would be a fast ionic conductor with low activation barriers for lithium-ion hopping. Origin of this discrepancy is elusive to date. Herein, combined first-principles calculations and high-angle annular dark-field scanning transmission electron microscopy analyses reveal that typical triplite structure is composed of nanodomains consisting of corner-shared FeO4F2 octahedra, whereas their domain boundaries are regions of mixed corner/edge-shared FeO4F2 octahedra. More importantly, these locally disordered domain boundaries significantly reduce the overall lithium diffusivity of the materials. Inspired by these findings, this study redesigns triplite structure with sufficiently small sizes to avoid local bottlenecks arising from the domain boundaries, successfully achieving nearly full lithium extraction/reinsertion with high power and energy density. This work represents the first direct observation of the presence of domain boundaries within a crystalline structure playing a critical role in governing the lithium diffusivity in a battery electrode.The origin of slow kinetics of triplite electrode material is demonstrated for the first time. This study unveils that triplite LiFeSO4F particle is generally comprised of “nanodomains” of characteristic transition-metal arrangements, and the domain boundaries significantly reduce the overall lithium diffusivity. This work represents presence of domain boundaries within a crystalline structure playing a critical role in governing the lithium diffusivity.
      PubDate: 2017-10-12T14:17:40.697087-05:
      DOI: 10.1002/aenm.201701408
  • Accurate Determination of Coulombic Efficiency for Lithium Metal Anodes
           and Lithium Metal Batteries
    • Authors: Brian D. Adams; Jianming Zheng, Xiaodi Ren, Wu Xu, Ji-Guang Zhang
      Abstract: Lithium (Li) metal is an ideal anode material for high energy density batteries. However, the low Coulombic efficiency (CE) and the formation of dendrites during repeated plating and stripping processes have hindered its applications in rechargeable Li metal batteries. The accurate measurement of Li CE is a critical factor to predict the cycle life of Li metal batteries, but the measurement of Li CE is affected by various factors that often lead to conflicting values reported in the literature. Here, several parameters that affect the measurement of Li CE are investigated and a more accurate method of determining Li CE is proposed. It is also found that the capacity used for cycling greatly affects the stabilization cycles and the average CE. A higher cycling capacity leads to faster stabilization of Li anode and a higher average CE. With a proper operating protocol, the average Li CE can be increased from 99.0% to 99.5% at a high capacity of 6 mA h cm−2 (which is suitable for practical applications) when a high-concentration ether-based electrolyte is used.Electrochemical methods are developed to accurately measure the Coulombic efficiency (CE) of lithium metal anodes and lithium metal batteries. The amount of Li consumed during plating/stripping cycling is quantified and used to estimate the cycle life of Li metal batteries. With the proper electrolyte, Li metal can be cycled with a CE of 99.5% at high capacity.
      PubDate: 2017-10-11T07:04:27.204486-05:
      DOI: 10.1002/aenm.201702097
  • Deformable and Transparent Ionic and Electronic Conductors for Soft Energy
    • Authors: Sangbaek Park; Kaushik Parida, Pooi See Lee
      Abstract: The recent boom in deformable or stretchable electronics, flexible transparent displays/screens, and their integration into the human body has facilitated the development of multifunctional energy devices that are stretchable, transparent, wearable, and/or biocompatible while meeting the energy or power requirements. The development of soft energy systems begins with the preparation of relevant conductors and the design of innovative device configurations. In this study, recent advances and trends in stretchable and transparent electronic and ionic conductors are reviewed coupled with the growing efforts to use them for soft energy storage and conversion systems. Stretchable transparent ionic conductors present possibilities for use as current collectors and electrolytes in soft electronic/energy devices, providing novel insight into biofriendly systems for an effective human–machine interaction. Moreover, representative examples that demonstrate soft energy devices based on stretchable transparent ionic/electronic conductors are discussed in detail. Furthermore, the challenges and perspectives of developing novel stretchable transparent conductors and device configurations with tailored features are also considered.The latest advances in stretchable transparent ionic and electronic conductors are reviewed with a focus on the integration of them into soft energy storage and conversion systems. The fundamental insights, challenges, and opportunities for this emerging field of materials science are also discussed to offer some guidelines for the future innovative development.
      PubDate: 2017-09-14T11:42:19.369963-05:
      DOI: 10.1002/aenm.201701369
  • Conjugated Polymers Based on Difluorobenzoxadiazole toward Practical
           Application of Polymer Solar Cells
    • Authors: Junyi Wang; Shiliang Wang, Chunhui Duan, Fallon J. M. Colberts, Jiangquan Mai, Xi Liu, Xiao'e Jia, Xinhui Lu, René A. J. Janssen, Fei Huang, Yong Cao
      Abstract: To advance polymer solar cells (PSCs) toward real-world applications, it is crucial to develop materials that are compatible with a low-cost large-scale manufacturing technology. In this context, a practically useful polymer should fulfill several critical requirements: the capability to provide high power conversion efficiencies (PCEs) via low-cost fabrication using environmentally friendly solvents under mild thermal conditions, resulting in an active layer that is thick enough to minimize defects in large-area films. Here, the development of new photovoltaic polymers is reported through rational molecular design to meet these requirements. Benzodithiophene (BDT)-difluorobenzoxadiazole (ffBX)-2-decyltetradecyl (DT), a wide-bandgap polymer based on ffBX and BDT emerges as the first example that fulfills the qualifications. When blended with a low-cost acceptor (C60-fullerene derivative), BDT-ffBX-DT produces a PCE of 9.4% at active layer thickness over 250 nm. BDT-ffBX-DT devices can be fabricated from nonhalogenated solvents at low processing temperature. The success of BDT-ffBX-DT originates from its appropriate electronic structure and charge transport characteristics, in combination with a favorable face-on orientation of the polymer backbone in blends, and the ability to form proper phase separation morphology with a fibrillar bicontinuous interpenetrating network in bulk-heterojunction films. With these characteristics, BDT-ffBX-DT represents a meaningful step toward future everyday applications of polymer solar cells.Two new conjugated polymers based on difluorobenzoxadiazole bring real-world applications of polymer solar cells closer. They integrate multiple advantages including high power conversion efficiency built on low-cost acceptors, allowing thick active layers, and processability from green solvents under mild conditions. Particularly, benzodithiophene-difluorobenzoxadiazole-2-decyltetradecyl (BDT-ffBX-DT) is a champion in meeting a comprehensive list of prerequisites for future application of polymer solar cells.
      PubDate: 2017-09-11T01:31:58.772656-05:
      DOI: 10.1002/aenm.201702033
  • Accurate Characterization of Triple-Junction Polymer Solar Cells
    • Authors: Dario Di Carlo Rasi; Koen H. Hendriks, Martijn M. Wienk, René A. J. Janssen
      Abstract: Triple-junction device architectures represent a promising strategy to highly efficient organic solar cells. Accurate characterization of such devices is challenging, especially with respect to determining the external quantum efficiency (EQE) of the individual subcells. The specific light bias conditions that are commonly used to determine the EQE of a subcell of interest cause an excess of charge generation in the two other subcells. This results in the build-up of an electric field over the subcell of interest, which enhances current generation and leads to an overestimation of the EQE. A new protocol, involving optical modeling, is developed to correctly measure the EQE of triple-junction organic solar cells. Apart from correcting for the build-up electric field, the effect of light intensity is considered with the help of representative single-junction cells. The short-circuit current density (JSC) determined from integration of the EQE with the AM1.5G solar spectrum differs by up to 10% between corrected and uncorrected protocols. The results are validated by comparing the EQE experimentally measured to the EQE calculated via optical-electronic modeling, obtaining an excellent agreement.The external quantum efficiency of triple-junction cells is accurately measured following a new protocol that takes into account light bias and voltage bias. Integration of the external quantum efficiency to determine the short-circuit current density matches with the value under simulated AM1.5G illumination conditions and results in a power conversion efficiency of 9.77 ± 0.29%.
      PubDate: 2017-09-11T01:25:53.784784-05:
      DOI: 10.1002/aenm.201701664
  • Charge Carrier Extraction in Organic Solar Cells Governed by Steady-State
    • Authors: Vincent M. Le Corre; Azadeh Rahimi Chatri, Nutifafa Y. Doumon, L. Jan Anton Koster
      Abstract: Charge transport in organic photovoltaic (OPV) devices is often characterized by steady-state mobilities. However, the suitability of steady-state mobilities to describe charge transport has recently been called into question, and it has been argued that dispersion plays a significant role. In this paper, the importance of the dispersion of charge carrier motion on the performance of organic photovoltaic devices is investigated. An experiment to measure the charge extraction time under realistic operating conditions is set up. This experiment is applied to different blends and shows that extraction time is directly related to the geometrical average of the steady-state mobilities. This demonstrates that under realistic operating conditions the steady-state mobilities govern the charge extraction of OPV and gives a valuable insight in device performance.Charge transport in organic photovoltaic devices is often characterized by steady-state mobilities. However, the suitability of steady-state mobilities to describe charge transport has recently been called into question and it has been argued that dispersion plays a significant role. In this paper, the importance of the dispersion of charge carrier motion on the performance of organic photovoltaic devices is investigated.
      PubDate: 2017-09-11T01:25:28.541875-05:
      DOI: 10.1002/aenm.201701138
  • Efficient Perovskite Solar Cells over a Broad Temperature Window: The Role
           of the Charge Carrier Extraction
    • Authors: Shuyan Shao; Jian Liu, Hong-Hua Fang, Li Qiu, Gert H. ten Brink, Jan C. Hummelen, L. Jan Anton Koster, Maria Antonietta Loi
      Abstract: The mechanism behind the temperature dependence of the device performance in hybrid perovskite solar cells (HPSCs) is investigated systematically. The power conversion efficiency (PCE) of the reference cell using [60]PCBM as electron extraction layer (EEL) drops significantly from 11.9% at 295 K to 7% at 180 K. The deteriorated charge carrier extraction is found as the dominant factor causing this degradation. Temperature dependent spectroscopy and charge transport studies demonstrate that the poor electron transport in the [60]PCBM EEL at low temperature leads to inefficient charge carrier extraction. It is further demonstrated that the n-type doping of [60]PCBM EEL or the use of an EEL (fulleropyrrolidine with a triethylene glycol monoethyl ether side chain) with higher electron transport capability is an effective strategy to achieve HPSCs working efficiently over a broad temperature range. The devices fabricated with these highly performing EELs have PCEs at 180 K of 16.7% and 18.2%, respectively. These results support the idea that the temperature dependence of the electron transport in the EELs limits the device performance in HPSCs, especially at lower temperatures and they also give directions toward further improvement of the PCE of HPSCs at realistic operating temperatures.The temperature dependence of the figures of merit of hybrid perovskite solar cells (HPSCs) is dominated by the electron extraction layer (EEL). At low temperature, the device using [60]PCBM as EEL shows significant lowering of the performance due to the poor electron transport capability of [60]PCBM. By n-type doping [60]PCBM, highly efficient HPSCs over a broad temperature range are achieved.
      PubDate: 2017-09-07T11:25:54.393179-05:
      DOI: 10.1002/aenm.201701305
  • From Ionogels to Biredox Ionic Liquids: Some Emerging Opportunities for
           Electrochemical Energy Storage and Conversion Devices
    • Authors: André Vioux; Benoit Coasne
      Abstract: Ionic liquids (ILs) continue to receive attention for applications in electrochemistry because of their unique properties as charge carriers (electrolytes) and redox shuttles (solar cells) and their ability to promote energy storage either electrostatically (supercapacitors) or chemically (secondary batteries). More specifically, the confinement of ILs in nanopores or the adsorption at surfaces, are considered a promising strategy for all solid-state energy storage and conversion devices. Upon such immobilization, one benefits from the specific properties of ILs (large electrochemical window, relatively high ionic conductivity, task-specific functionalities, etc.) combined with surface and confinement effects that can be tuned by playing with the porosity and chemical nature of the host. Here, some emerging applications of ILs in electrochemistry are first discussed: silica-based ionogels as solid electrolytes and systems that involve carbon host substrates, as typical electrode materials in electrical double layer capacitors and lithium secondary batteries. Also, a non-exhaustive, yet a comprehensive picture of the confinement and surface effects at play in such applications is presented. Then, the confinement of task-specific ILs such as protonic ILs, IL lithium salts, and biredox ILs, is discussed, which paves the way for promising perspectives. Finally, some concluding remarks are reported and directions for future work are suggested.Confinement of ionic liquids in inorganic porous hosts opens the door to modular materials that can be tuned as electrochemical devices. Some emerging applications are presented, including ionogels as solid electrolytes and carbon-based materials for electrical double layer capacitors and lithium secondary batteries. The use of task-specific ionic liquids such as protonic and biredox ionic liquids is also discussed.
      PubDate: 2017-09-04T07:36:17.752736-05:
      DOI: 10.1002/aenm.201700883
  • A Solution-Processable Polymer Photocatalyst for Hydrogen Evolution from
    • Authors: Duncan J. Woods; Reiner Sebastian Sprick, Charlotte L. Smith, Alexander J. Cowan, Andrew I. Cooper
      Abstract: Direct photocatalytic water splitting is an attractive strategy for clean energy production, but multicomponent nanostructured systems that mimic natural photosynthesis can be difficult to fabricate because of the insolubility of most photocatalysts. Here, a solution-processable organic polymer is reported that is a good photocatalyst for hydrogen evolution from water, either as a powder or as a thin film, suggesting future applications for soluble conjugated organic polymers in multicomponent photocatalysts for overall water splitting.Multicomponent nanostructured systems that mimic natural photosynthesis can be difficult to fabricate because of the insolubility of most photocatalysts. Here, a solution-processable organic polymer is reported that is a good photocatalyst for hydrogen evolution from water, either as a powder or as a thin film, suggesting future applications for soluble conjugated organic polymers in multicomponent photocatalysts for overall water splitting.
      PubDate: 2017-09-01T14:50:37.653396-05:
      DOI: 10.1002/aenm.201700479
  • Benzylamine-Treated Wide-Bandgap Perovskite with High
           Thermal-Photostability and Photovoltaic Performance
    • Authors: Yang Zhou; Feng Wang, Yu Cao, Jian-Pu Wang, Hong-Hua Fang, Maria Antonietta Loi, Ni Zhao, Ching-Ping Wong
      Abstract: Mixed iodide-bromide organolead perovskites with a bandgap of 1.70–1.80 eV have great potential to boost the efficiency of current silicon solar cells by forming a perovskite-silicon tandem structure. Yet, the stability of the perovskites under various application conditions, and in particular combined light and heat stress, is not well studied. Here, FA0.15Cs0.85Pb(I0.73Br0.27)3, with an optical bandgap of ≈1.72 eV, is used as a model system to investigate the thermal-photostability of wide-bandgap mixed halide perovskites. It is found that the concerted effect of heat and light can induce both phase segregation and decomposition in a pristine perovskite film. On the other hand, through a postdeposition film treatment with benzylamine (BA) molecules, the highly defective regions (e.g., film surface and grain boundaries) of the film can be well passivated, thus preventing the progression of decomposition or phase segregation in the film. Besides the stability improvement, the BA-modified perovskite solar cells also exhibit excellent photovoltaic performance, with the champion device reaching a power conversion efficiency of 18.1%, a stabilized power output efficiency of 17.1% and an open-circuit voltage (Voc) of 1.24 V.Using a postdeposition film treatment with benzylamine (BA) molecules, the highly defective regions of the wide-bandgap FA0.15Cs0.85Pb(I1−xBrx)3 films can be well passivated, thus preventing the progression of decomposition or phase segregation in the film during combined heat and light stress. The BA-treated perovskite solar cells exhibit a stabilized power output efficiency of 17.1% and an open-circuit voltage (Voc) of 1.24 V.
      PubDate: 2017-09-01T14:48:38.720457-05:
      DOI: 10.1002/aenm.201701048
  • Self-Powered Gyroscope Ball Using a Triboelectric Mechanism
    • Authors: Qiongfeng Shi; Han Wu, Hao Wang, Hanxiang Wu, Chengkuo Lee
      Abstract: Healthcare monitoring systems can provide important health state information by monitoring the biomechanical parameter or motion of body segments. Triboelectric nanogenerators (TENGs) as self-powered motion sensors have been developed rapidly to convert external mechanical change into electrical signal. However, research effort on using TENGs for multiaxis acceleration sensing is very limited. Moreover, TENG has not been demonstrated for rotation sensing to date. Herein, for the first time, a 3D symmetric triboelectric nanogenerator-based gyroscope ball (T-ball) with dual capability of energy harvesting and self-powered sensing is proposed for motion monitoring including multiaxis acceleration and rotation. The T-ball can harvest energy under versatile scenarios and function as self-powered 3D accelerometer with sensitivity of 6.08, 5.87, and 3.62 V g−1 . Furthermore, the T-ball can serve as a self-powered gyroscope for rotation sensing with sensitivity of 3.5 mV so−1. It shows good performance in hand motion recognition and human activity state monitoring applications. The proposed T-ball as a self-powered gyroscope for advanced motion sensing can pave the way to a self-powered, more accurate, and more complete motion monitoring system.A self-powered gyroscope based on triboelectric mechanism is proposed by using a 3D symmetric triboelectric nanogenerator ball (T-ball). The T-ball can harvest energy under diversified circumstances and function as self-powered advanced motion sensor, that is, a 3D accelerometer and gyroscope. When mounted on humans, the T-ball can provide useful real-time information for a motion monitoring system.
      PubDate: 2017-09-01T14:47:36.681295-05:
      DOI: 10.1002/aenm.201701300
  • Flexible Composite Solid Electrolyte Facilitating Highly Stable “Soft
           Contacting” Li–Electrolyte Interface for Solid State Lithium-Ion
    • Authors: Luyi Yang; Zijian Wang, Yancong Feng, Rui Tan, Yunxing Zuo, Rongtan Gao, Yan Zhao, Lei Han, Ziqi Wang, Feng Pan
      Abstract: A flexible composite solid electrolyte membrane consisting of inorganic solid particles (Li1.3Al0.3Ti1.7(PO4)3), polyethylene oxide (PEO), and boronized polyethylene glycol (BPEG) is prepared and investigated. This membrane exhibits good stability against lithium dendrite, which can be attributed to its well-designed combination components: the compact inorganic lithium ion conducting layer provides the membrane with good mechanical strength and physically barricades the free growth of lithium dendrite; while the addition of planar BPEG oligomers not only disorganizes the crystallinity of the PEO domain, leading to good ionic conductivity, but also facilitates a “soft contact” between interfaces, which not only chemically enables homogeneous lithium plating/stripping on the lithium metal anode, but also reduces the polarization effects. In addition, by employing this membrane to a LiFePO4/Li cell and testing its galvanostatic cycling performances at 60 °C, capacities of 158.2 and 94.2 mA h g−1 are delivered at 0.1 C and 2 C, respectively.A flexible composite solid electrolyte membrane consisting of polymer and Li-ion conductive ceramic is prepared and investigated. The addition of boronized polyethylene glycol oligomer improves its ionic conductivity, and facilitates a better contact between the lithium metal and the electrolyte, resulting in a smooth lithium interface after cycling.
      PubDate: 2017-09-01T14:44:39.904236-05:
      DOI: 10.1002/aenm.201701437
  • Enhancing the Photovoltaic Performance via Vertical Phase Distribution
           Optimization in Small Molecule:PC71BM Blends
    • Authors: Yajie Zhang; Dan Deng, Zaiyu Wang, Yuheng Wang, Jianqi Zhang, Jin Fang, Yang Yang, Guanghao Lu, Wei Ma, Zhixiang Wei
      Abstract: Bulk heterojunction (BHJ) morphologies are vital to the device performance of organic solar cells (OSCs), including phase separation in lateral and vertical directions. However, the morphology developed from the blend solution is not easily predicted and controlled, especially in the vertical direction, because the BHJ morphology is kinetically frozen during the rapid solvent evaporation process. Here, a simple approach to control BHJ morphologies with optimized phase distribution for small molecule:[6,6]-phenyl-C71-butyric acid methyl ester (PC71 BM) blends by enhancing the substrate temperature during the spin-coating process. Three molecules with various fluorine atoms in the end acceptor units are selected. The relationship among molecular structures, substrate temperature effects on the morphology, and device performances are symmetrically investigated. Low temperature induces a multiple-sublayer-like architecture with significantly varied distributions of composition, morphology, and localized state energy, while high processing temperature induces more uniform film. The short-circuit current, open-circuit voltage, and fill factor of the devices are tuned with synergic improvement of efficiency toward over 10% and 11% for conventional and inverted devices. This work reveals the origination of vertical phase segregation, and provides a facile strategy to optimize the hierarchical phase separation for enhancing the performance of OSCs.Vertical phase segregation in small molecule photovoltaic devices is manipulated via substrate temperature tuning. Low temperature induces multiple-sublayer-like architecture with significantly varied distributions of composition, morphology, and localized state energy, while high processing temperature induces more uniform film. The parameters of devices are largely tuned with synergic improvement of efficiency toward over 10% and 11% for conventional and inverted devices.
      PubDate: 2017-09-01T14:44:00.073624-05:
      DOI: 10.1002/aenm.201701548
  • Polymer:Nonfullerene Bulk Heterojunction Solar Cells with Exceptionally
           Low Recombination Rates
    • Authors: Nicola Gasparini; Michael Salvador, Thomas Heumueller, Moses Richter, Andrej Classen, Shreetu Shrestha, Gebhard J. Matt, Sarah Holliday, Sebastian Strohm, Hans-Joachim Egelhaaf, Andrew Wadsworth, Derya Baran, Iain McCulloch, Christoph J. Brabec
      Abstract: Organic semiconductors are in general known to have an inherently lower charge carrier mobility compared to their inorganic counterparts. Bimolecular recombination of holes and electrons is an important loss mechanism and can often be described by the Langevin recombination model. Here, the device physics of bulk heterojunction solar cells based on a nonfullerene acceptor (IDTBR) in combination with poly(3-hexylthiophene) (P3HT) are elucidated, showing an unprecedentedly low bimolecular recombination rate. The high fill factor observed (above 65%) is attributed to non-Langevin behavior with a Langevin prefactor (β/βL) of 1.9 × 10−4. The absence of parasitic recombination and high charge carrier lifetimes in P3HT:IDTBR solar cells inform an almost ideal bimolecular recombination behavior. This exceptional recombination behavior is explored to fabricate devices with layer thicknesses up to 450 nm without significant performance losses. The determination of the photoexcited carrier mobility by time-of-flight measurements reveals a long-lived and nonthermalized carrier transport as the origin for the exceptional transport physics. The crystalline microstructure arrangement of both components is suggested to be decisive for this slow recombination dynamics. Further, the thickness-independent power conversion efficiency is of utmost technological relevance for upscaling production and reiterates the importance of understanding material design in the context of low bimolecular recombination.Nonfullerene-based organic solar cells with an unprecedentedly low bimolecular recombination rate are presented. The absence of parasitic recombination and high carrier lifetimes in the devices inform an almost ideal bimolecular recombination behavior with a Langevin prefactor (β/βL) of 1.9 × 10−4. This exceptional recombination behavior allows the fabrication of solar cells with layer thicknesses up to 450 nm without significant performance losses.
      PubDate: 2017-09-01T14:43:21.659589-05:
      DOI: 10.1002/aenm.201701561
  • Unity Convoluted Design of Solid Li-Ion Battery and Triboelectric
           Nanogenerator for Self-Powered Wearable Electronics
    • Authors: Xi Liu; Kun Zhao, Zhong Lin Wang, Ya Yang
      Abstract: Wearable electronics suffer from severe power shortage due to limited working time of Li-ion batteries, and there is a desperate need to build a hybrid device including energy scavenging and storing units. However, previous attempts to integrate the two units are mainly based on simple external connections and assembly, so that maintaining small volume and low manufacturing cost becomes increasingly challenging. Here a convoluted power device is presented by hybridizing internally a solid Li-ion battery (SLB) and a triboelectric nanogenerator (TENG), so that the two units are one inseparable entity. The fabricated device acts as a TENG that can deliver a peak output power of 7.4 mW under a loading resistance of 7 MΩ, while the device also acts as an SLB to store the obtained electric energy. The device can be mounted on a human shoe to sustainably operate a green light-emitting diode, thus demonstrating potential for self-powered wearable electronics.A convoluted power device made by internally hybridizing a solid Li-ion battery and a triboelectric nanogenerator, so that the two units are one inseparable entity, is reported. The device can be mounted on a human shoe to operate a green light-emitting diode, demonstrating potential for self-powered wearable electronics.
      PubDate: 2017-09-01T14:42:35.693046-05:
      DOI: 10.1002/aenm.201701629
  • Selective Etching of Nitrogen-Doped Carbon by Steam for Enhanced
           Electrochemical CO2 Reduction
    • Authors: Xiaoqi Cui; Zhiyong Pan, Lijuan Zhang, Huisheng Peng, Gengfeng Zheng
      Abstract: Nitrogen-doped carbon structures have recently been demonstrated as a promising candidate for electrocatalytic CO2 reduction, while in the meantime the pyridinic and graphitic nitrogen atoms also present high activities for electroreduction of water. Here, an etching strategy that uses hot water steam to preferentially bind to pyridinic and graphitic nitrogen atoms and subsequently etch them in carbon frameworks is reported. As a result, pyrrolic nitrogen atoms with low water affinity are retained after the steam etching, with a much increased level of among all nitrogen species from 22.1 to 55.9%. The steam-etched nitrogen-doped carbon catalyst enables excellent electrocatalytic CO2 reduction performance but low hydrogen evolution reaction activity, suggesting a new approach for tuning electrocatalyst activity.A steam-etching approach is developed to tune the configurations of nitrogen dopants in carbon frameworks. The carbon atoms around pyridinic and graphitic N are more susceptible to steam etching because of their stronger binding capability to water molecules. The obtained pyrrolic-N-rich catalyst shows much-enhanced CO2 reduction catalytic activity and hydrogen evolution reaction (HER) suppression.
      PubDate: 2017-09-01T00:56:42.855992-05:
      DOI: 10.1002/aenm.201701456
  • Thick Film Polymer Solar Cells Based on
           Naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole Conjugated Polymers with
           Efficiency over 11%
    • Authors: Yaocheng Jin; Zhiming Chen, Manjun Xiao, Jiajun Peng, Baobing Fan, Lei Ying, Guichuan Zhang, Xiao-Fang Jiang, Qingwu Yin, Ziqi Liang, Fei Huang, Yong Cao
      Abstract: Two novel narrow bandgap π-conjugated polymers based on naphtho[1,2-c:5,6-c′]bis([1,2,5]thiadiazole) (NT) unit are developed, which contain the thiophene or benzodithiophene flanked with alkylthiophene as the electron-donating segment. Both copolymers exhibit strong aggregations both in solution and as thin films. The resulting copolymers with higher molecular weight show higher photovoltaic performance by virtue of the enhanced short-circuit current densities and fill factors, which can be attributed to their higher absorptivity and formation of more favorable film morphologies. Polymer solar cells (PSCs) fabricated with the copolymer PNTT achieve remarkable power conversion efficiencies (PCEs) > 11% based on both conventional and inverted structures at the photoactive layer thickness of 280 nm, which is the highest value so far observed from NT-based copolymers. Of particular interest is that the device performances are insensitive to the thickness of the photoactive layer, for which the PCEs > 10% can be achieved with film thickness ranging from 150 to 660 nm, and the PCE remains >9% at the thickness over 1 µm. These findings demonstrate that these NT-based copolymers can be promising candidates for the construction of thick film PSCs toward low-cost roll-to-roll processing technology.Two novel conjugated polymers based on naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazol (NT) as the electron-deficient unit are developed for polymer solar cells (PSCs). The fabricated PSCs based on the high molecular weight copolymer and the fullerene acceptor ([6,6]-phenyl-C71-butyric acid methyl ester) present remarkable power conversion efficiencies over 10% with the bulk-heterojunction film thickness ranging from 150 to 660 nm.
      PubDate: 2017-09-01T00:56:04.540999-05:
      DOI: 10.1002/aenm.201700944
  • Graphene-Based Electron Transport Layers in Perovskite Solar Cells: A
           Step-Up for an Efficient Carrier Collection
    • Authors: Francesco Biccari; Fabio Gabelloni, Erica Burzi, Massimo Gurioli, Sara Pescetelli, Antonio Agresti, Antonio Esaú Del Rio Castillo, Alberto Ansaldo, Emmanuel Kymakis, Francesco Bonaccorso, Aldo Di Carlo, Anna Vinattieri
      Abstract: The electron transport layer (ETL) plays a fundamental role in perovskite solar cells. Recently, graphene-based ETLs have been proved to be good candidate for scalable fabrication processes and to achieve higher carrier injection with respect to most commonly used ETLs. Here, the effects of different graphene-based ETLs in sensitized methylammonium lead iodide (MAPI) solar cells are experimentally studied. By means of time-integrated and picosecond time-resolved photoluminescence techniques, the carrier recombination dynamics in MAPI films embedded in different ETLs is investigated. Using graphene doped mesoporous TiO2 (G+mTiO2) with the addition of a lithium-neutralized graphene oxide (GO-Li) interlayer as ETL, it is found find that the carrier collection efficiency is increased by about a factor two with respect to standard mTiO2. Taking advantage of the absorption coefficient dispersion, the MAPI layer morphology is probed, along the thickness, finding that the MAPI embedded in the ETL composed by G+mTiO2 plus GO-Li brings to a very good crystalline quality of the MAPI layer with a trap density about one order of magnitude lower than that found with the other ETLs. In addition, this ETL freezes MAPI at the tetragonal phase, regardless of the temperature. Graphene-based ETLs can open the way to significant improvement of perovskite solar cells.The effects of different graphene-based electron transport layers (ETLs) in perovskite methylammonium lead iodide (MAPI) solar cells are experimentally investigated. Using graphene-doped mesoporous TiO2 (mTiO2) with the addition of a lithium-neutralized graphene oxide interlayer as the ETL, the carrier collection efficiency is increased by approximately a factor two with respect to standard mTiO2.
      PubDate: 2017-09-01T00:55:46.34344-05:0
      DOI: 10.1002/aenm.201701349
  • Design and Fabrication of a Precious Metal-Free Tandem Core–Shell p+n
           Si/W-Doped BiVO4 Photoanode for Unassisted Water Splitting
    • Authors: Pongkarn Chakthranont; Thomas R. Hellstern, Joshua M. McEnaney, Thomas F. Jaramillo
      Abstract: Tandem photoelectrochemical water splitting cells utilizing crystalline Si and metal oxide photoabsorbers are promising for low-cost solar hydrogen production. This study presents a device design and a scalable fabrication scheme for a tandem heterostructure photoanode: p+n black silicon (Si)/SnO2 interface/W-doped bismuth vanadate (BiVO4)/cobalt phosphate (CoPi) catalyst. The black-Si not only provides a substantial photovoltage of 550 mV, but it also serves as a conductive scaffold to decrease charge transport pathlengths within the W-doped BiVO4 shell. When coupled with cobalt phosphide (CoP) nanoparticles as hydrogen evolution catalysts, the device demonstrates spontaneous water splitting without employing any precious metals, achieving an average solar-to-hydrogen efficiency of 0.45% over the course of an hour at pH 7. This fabrication scheme offers the modularity to optimize individual cell components, e.g., Si nanowire dimensions and metal oxide film thickness, involving steps that are compatible with fabricating monolithic devices. This design is general in nature and can be readily adapted to novel, higher performance semiconducting materials beyond BiVO4 as they become available, which will accelerate the process of device realization.A tandem heterojunction photoanode structure: p+n black-Si core/SnO2 interface/W-doped bismuth vanadate (BiVO4) shell/cobalt phosphate (CoPi) catalyst coupled with a cobalt phosphide (CoP) counter electrode demonstrates unassisted water splitting without the use of precious metal catalysts. The fabrication scheme offers wafer-scaled production and is applicable to other wide band gap semiconductors to enable the development of silicon (Si)-based tandem heterostrucure photoelectrodes.
      PubDate: 2017-08-30T11:06:01.443739-05:
      DOI: 10.1002/aenm.201701515
  • Hierarchical Multicomponent Electrode with Interlaced Ni(OH)2 Nanoflakes
           Wrapped Zinc Cobalt Sulfide Nanotube Arrays for Sustainable
           High-Performance Supercapacitors
    • Authors: Junaid Ali Syed; Jun Ma, Baogang Zhu, Shaochun Tang, Xiangkang Meng
      Abstract: High energy density, fast recharging ability, and sustained cycle life are the primary requisite of supercapacitors (SCs); these necessities can be fulfilled by engineering a smart current collector with hierarchical combination of different active materials. This study reports a multicomponent design of hierarchical zinc cobalt sulfide (ZCS) hollow nanotube arrays wrapped with interlaced ultrathin Ni(OH)2 nanoflakes for high-performance electrodes. The ZCS exhibits a unique pentagonal cross-section and a rough surface that facilitates the deposition of Ni(OH)2 nanoflakes with a thickness of 7.5 nm. The ZCS/Ni(OH)2 hierarchical electrode exhibits a high specific capacitance of 2156 F g−1 and excellent cyclic stability with 94% retention over 3000 cycles. This is attributed to enhanced redox reactions, the direct growth of arrays on 3D porous foam acting as a “superhighway” for electron transport, and the increased availability of electrochemical active sites provided by the ultrathin Ni(OH)2 flakes that also sustain the stability of the electrode by sacrificing themselves during long charge/discharge cycles. Symmetric SCs are assembled to achieve high energy density of 74.93 W h kg−1 and exhibit superior cyclic stability of 78% retention with 81% coulombic efficiency over 10 000 cycles.Hierarchical arrays of zinc cobalt sulfide (ZCS) hollow nanotubes exhibiting a well-defined pentagonal cross-section wrapped with interlaced ultrathin (7.5 nm) Ni(OH)2 nanoflakes are synthesized. The well-designed nanoarchitecture allows the ZCS/Ni(OH)2 electrodes to achieve high specific capacitances, good rate capability, and excellent cycling stability. An assembled symmetric supercapacitors (SC) delivers higher energy densities than most of the previously reported asymmetric SCs.
      PubDate: 2017-08-28T12:47:50.871288-05:
      DOI: 10.1002/aenm.201701228
  • Surface Free Energy-Induced Assembly to the Synthesis of Grid-Like
           Multicavity Carbon Spheres with High Level In-Cavity Encapsulation for
           Lithium–Sulfur Cathode
    • Authors: Lu-Hua Zhang; Bin He, Wen-Cui Li, An-Hui Lu
      Abstract: Carbon microcapsules with a large interior cavity and porous shell are ideal hosts for guest species, while to maximize in-cavity volume has always been a challenge. Herein, a surface free energy-induced assembly approach is proposed for synthesis of multicavity carbon spheres (MCC). When used as a host for lithium–sulfur cathodes, MCC are fully accessible for sulfur—with high level in-cavity encapsulation ability of grid-like cavities. The crucial point for this assembly approach is the employment of small sized nanoemulsions with high homogeneity as primary building blocks. Spontaneous aggregation and assembly of substructural units are processing in following hydrothermal synthesis induced by reduction of surface free energy of system. As a result, multicavity structure is formed, where the size and number of cavities can be modulated by changing size of nanoemulsion and concentration of polymer. Confined pyrolysis enables to further enlarge cavity size compared to regular pyrolysis. The carbon–sulfur cathode exhibits excellent cycling stability and rate performance, i.e., high capacity of 943 and 869 mA h g−1 after 200 cycles at current density of 0.5 and 2.0 C. The strategy has paved the way for custom-ordered synthesis of nanostructured carbon with keen demands in high loading capacity of guest species.A surface free energy-induced assembly approach for the synthesis of multicavity carbon spheres by a well-controlled solution synthesis route is demonstrated. The size and number of the cavities can be controlled by varying nanoemulsion size and polymer concentration. The multicavity interconnected with porous walls is fully accessible for sulfur species, demonstrating the high level in-cavity encapsulation ability of grid-like cavities.
      PubDate: 2017-08-28T05:31:46.255569-05:
      DOI: 10.1002/aenm.201701518
  • Post Iron Decoration of Mesoporous Nitrogen-Doped Carbon Spheres for
           Efficient Electrochemical Oxygen Reduction
    • Authors: Zhuang Liu; Fei Sun, Lin Gu, Gen Chen, Tongtong Shang, Jing Liu, Zaiyuan Le, Xianyang Li, Hao Bin Wu, Yunfeng Lu
      Abstract: Iron–nitrogen–carbon (Fe–N–C) catalysts are considered as the most promising nonprecious metal catalysts for oxygen reduction reactions (ORRs). Their synthesis generally involves complex pyrolysis reactions at high temperature, making it difficult to optimize their composition, pore structure, and active sites. This study reports a simple synthesis strategy by reacting preformed nitrogen-doped carbon scaffolds with iron pentacarbonyl, a liquid precursor that can effectively form active sites with the nitrogen sites, enabling more effective control of the catalyst. The resultant catalyst possesses a well-defined mesoporous structure, a high surface area, and optimized active sites. The catalysts exhibit high ORR activity comparable to that of Pt/C catalyst (40% Pt loading) in alkaline media, with excellent stability and methanol tolerance. The synthetic strategy can be extended to synthesize other metal–N–C catalysts.A novel fabrication strategy for metal–N–C electrocatalysts based on the post metal decoration of mesoporous nitrogen spheres is developed. Such synthetic method enables the simple formation of iron-containing active sites on preformed nitrogen-doped carbon host. The good oxygen reduction reaction performance of the prepared Iron/nitrogen-doped mesoporous carbon catalyst is attributed to the synergistic effect between Fe–Nx sites and surface-oxidized Fe nanoparticles.
      PubDate: 2017-08-28T05:31:10.177199-05:
      DOI: 10.1002/aenm.201701154
  • Outstanding Performance of Hole-Blocking Layer-Free Perovskite Solar Cell
           Using Hierarchically Porous Fluorine-Doped Tin Oxide Substrate
    • Authors: Haejun Yu; Jong Woo Lee, Juyoung Yun, Kisu Lee, Jaehoon Ryu, Jungsup Lee, Doyk Hwang, Seong Keun Kim, Jyongsik Jang
      Abstract: Perovskite solar cells (PSCs) are of great interest in current photovoltaic research due to their extraordinary power conversion efficiency of ≈20% and boundless potentialities. The high efficiency has been mostly obtained from TiO2-based PSCs, where TiO2 is utilized as a hole-blocking, mesoporous layer. However, trapped charges and the light-induced photocatalytic effect of TiO2 seriously degrade the perovskite and preclude PSCs from being immediately commercialized. Herein, a simplified PSC is successfully fabricated by eliminating the problematic TiO2 layers, using instead a fluorine-doped tin oxide (FTO)/perovskite/hole–conductor/Au design. Simultaneously, the sluggish charge extraction at the FTO/perovskite interface is overcome by modifying the surface of the FTO to a porous structure using electrochemical etching. This surface engineering enables a substantial increase in the photocurrent density and mitigation of the hysteretic behavior of the pristine FTO-based PSC; a remarkable 19.22% efficiency with a low level of hysteresis is obtained. This performance is closely approaching that of conventional PSCs and may facilitate their commercialization due to improved convenience, lower cost, greater stability, and potentially more efficient mass production.Electrochemically etched fluorine-doped tin oxide (FTO) provides large surfacial area compared with commercial FTO and quickly extracts photoexcited electrons at the FTO/perovskite interface. Accordingly, the photocurrent density and performance of hole-blocking layer-free planar-type perovskite solar cell are improved, where the remarkable power conversion efficiency of 19.22% is achieved.
      PubDate: 2017-08-25T11:32:29.821347-05:
      DOI: 10.1002/aenm.201700749
  • Stable Inverted Planar Perovskite Solar Cells with
           Low-Temperature-Processed Hole-Transport Bilayer
    • Authors: Zhongmin Zhou; Xing Li, Molang Cai, Fengxian Xie, Yongzhen Wu, Zhang Lan, Xudong Yang, Yinghuai Qiang, Ashraful Islam, Liyuan Han
      Abstract: Low-temperature-processed perovskite solar cells (PSCs), which can be fabricated on rigid or flexible substrates, are attracting increasing attention because they have a wide range of potential applications. In this study, the stability of reduced graphene oxide and the ability of a poly(triarylamine) underlayer to improve the quality of overlying perovskite films to construct hole-transport bilayer by means of a low-temperature method are taken advantage of. The bilayer is used in both flexible and rigid inverted planar PSCs with the following configuration: substrate/indium tin oxide/reduced graphene oxide/polytriarylamine/CH3NH3PbI3/PCBM/bathocuproine/Ag (PCBM = [6,6]-phenyl-C61-butyric acid methyl ester). The flexible and rigid PSCs show power conversion efficiencies of 15.7 and 17.2%, respectively, for the aperture area of 1.02 cm2. Moreover, the PSC based the bilayer shows outstanding light-soaking stability, retaining ≈90% of its original efficiency after continuous illumination for 500 h at 100 mW cm−2.Low-temperature-processed hole-transport bilayer (reduced graphene oxide/polytriarylamine) is constructed to fabricate inverted perovskite solar cells (PSCs), which based on flexible and rigid substrates show power conversion efficiencies of 15.7 and 17.2% on the cells area of 1.02 cm2, respectively. In addition, the PSCs with the hole-transport bilayer show outstanding light-soaking stability.
      PubDate: 2017-08-25T11:32:07.289816-05:
      DOI: 10.1002/aenm.201700763
  • Progress in Theoretical Study of Metal Halide Perovskite Solar Cell
    • Authors: Zewen Xiao; Yanfa Yan
      Abstract: Lead halide perovskites have recently emerged as promising absorbers for fabricating low-cost and high-efficiency thin-film solar cells. The record power conversion efficiency of lead halide perovskite-based solar cells has rapidly increased from 3.8% in 2009 to 22.1% in early 2016. Such rapid improvement is attributed to the superior and unique photovoltaic properties of lead halide perovskites, such as the extremely high optical absorption coefficients and super-long photogenerated carrier lifetimes and diffusion lengths that are not seen in any other polycrystalline thin-film solar cell materials. In the past a few years, theoretical approaches have been extensively applied to understand the fundamental mechanisms responsible for the superior photovoltaic properties of lead halide perovskites and have gained significant insights. This review article highlights the important theoretical results reported in literature for the understanding of the unique structural, electronic, optical, and defect properties of lead halide perovskite materials. For comparison, we also review the theoretical results reported in literature for some lead-free perovskites, double perovskites, and nonperovskites.Progress in the theoretical study of metal halide perovskite absorber materials is reviewed with a focus on the understanding of the unique structural, electronic, optical, and defect properties of lead halide perovskites. For comparison, the theoretical results reported for some lead-free perovskites, double perovskites and nonperovskites are also reviewed.
      PubDate: 2017-08-25T11:31:51.378464-05:
      DOI: 10.1002/aenm.201701136
  • Fast Sodium Storage in TiO2@CNT@C Nanorods for High-Performance Na-Ion
    • Authors: Yuan-En Zhu; Leping Yang, Jian Sheng, Yanan Chen, Haichen Gu, Jinping Wei, Zhen Zhou
      Abstract: Na-ion capacitors have attracted extensive interest due to the combination of the merits of high energy density of batteries and high power density as well as long cycle life of capacitors. Here, a novel Na-ion capacitor, utilizing TiO2@CNT@C nanorods as an intercalation-type anode and biomass-derived carbon with high surface area as an ion adsorption cathode in an organic electrolyte, is reported. The advanced architecture of TiO2@CNT@C nanorods, prepared by electrospinning method, demonstrates excellent cyclic stability and outstanding rate capability in half cells. The contribution of extrinsic pseudocapacitance affects the rate capability to a large extent, which is identified by kinetics analysis. A key finding is that ion/electron transfer dynamics of TiO2@CNT@C could be effectively enhanced due to the addition of multiwalled carbon nanotubes. Also, the biomass-derived carbon with high surface area displays high specific capacity and excellent rate capability. Owing to the merits of structures and excellent performances of both anode and cathode materials, the assembled Na-ion capacitors provide an exceptionally high energy density (81.2 W h kg−1) and high power density (12 400 W kg−1) within 1.0–4.0 V. Meanwhile, the Na-ion capacitors achieve 85.3% capacity retention after 5000 cycles tested at 1 A g−1.High-performance Na-ion capacitors are fabricated with TiO2@CNT@C nanorods as an intercalation-type anode and biomass-derived carbon as an ion adsorption cathode in an organic electrolyte. Owing to the state-of-the-art architectures, excellent electrochemical performances, and perfect match in both electrodes, the hybrid devices demonstrate high energy-power integration and good cyclic stability.
      PubDate: 2017-08-25T11:29:17.646385-05:
      DOI: 10.1002/aenm.201701222
  • All-Nanomat Lithium-Ion Batteries: A New Cell Architecture Platform for
           Ultrahigh Energy Density and Mechanical Flexibility
    • Authors: Ju-Myung Kim; Jeong A. Kim, Seung-Hyeok Kim, In Sung Uhm, Sung Joong Kang, Guntae Kim, Sun-Young Lee, Sun-Hwa Yeon, Sang-Young Lee
      Abstract: The ongoing surge in demand for high-energy/flexible rechargeable batteries relentlessly drives technological innovations in cell architecture as well as electrochemically active materials. Here, a new class of all-nanomat lithium-ion batteries (LIBs) based on 1D building element-interweaved heteronanomat skeletons is demonstrated. Among various electrode materials, silicon (Si, for anode) and overlithiated layered oxide (OLO, for cathode) materials are chosen as model systems to explore feasibility of this new cell architecture and achieve unprecedented cell capacity. Nanomat electrodes, which are completely different from conventional slurry-cast electrodes, are fabricated through concurrent electrospinning (for polymeric nanofibers) and electrospraying (for electrode materials/carbon nanotubes (CNTs)). Si (or rambutan-shaped OLO/CNT composite) powders are compactly embedded in the spatially interweaved polymeric nanofiber/CNT heteromat skeletons that play a crucial role in constructing 3D-bicontinuous ion/electron transport pathways and allow for removal of metallic foil current collectors. The nanomat Si anodes and nanomat OLO cathodes are assembled with nanomat Al2O3 separators, leading to the fabrication of all-nanomat LIB full cells. Driven by the aforementioned structural/chemical uniqueness, the all-nanomat full cell shows exceptional improvement in electrochemical performance (notably, cell-based gravimetric energy density = 479 W h kgCell−1) and also mechanical deformability, which lie far beyond those achievable with conventional LIB technologies.All-nanomat (Si anode/Al2O3 separator/OLO cathode) lithium-ion battery full cells based on 1D building element-interweaved heteronanomat skeletons are presented as a new platform technology for advanced power sources. The heteronanomat architecture allows for formation of 3D-bicontinuous ion/electron transport pathways and elimination of metallic foil current collectors, resulting in exceptional improvements in the energy density (=479 W h kgCell−1) and mechanical deformability.
      PubDate: 2017-08-25T11:21:47.060986-05:
      DOI: 10.1002/aenm.201701099
  • Enhancing Charge Carrier Lifetime in Metal Oxide Photoelectrodes through
           Mild Hydrogen Treatment
    • Authors: Ji-Wook Jang; Dennis Friedrich, Sönke Müller, Marlene Lamers, Hannes Hempel, Sheikha Lardhi, Zhen Cao, Moussab Harb, Luigi Cavallo, René Heller, Rainer Eichberger, Roel van de Krol, Fatwa F. Abdi
      Abstract: Widespread application of solar water splitting for energy conversion is largely dependent on the progress in developing not only efficient but also cheap and scalable photoelectrodes. Metal oxides, which can be deposited with scalable techniques and are relatively cheap, are particularly interesting, but high efficiency is still hindered by the poor carrier transport properties (i.e., carrier mobility and lifetime). Here, a mild hydrogen treatment is introduced to bismuth vanadate (BiVO4), which is one of the most promising metal oxide photoelectrodes, as a method to overcome the carrier transport limitations. Time-resolved microwave and terahertz conductivity measurements reveal more than twofold enhancement of the carrier lifetime for the hydrogen-treated BiVO4, without significantly affecting the carrier mobility. This is in contrast to the case of tungsten-doped BiVO4, although hydrogen is also a donor type dopant in BiVO4. The enhancement in carrier lifetime is found to be caused by significant reduction of trap-assisted recombination, either via passivation or reduction of deep trap states related to vanadium antisite on bismuth or vanadium interstitials according to density functional theory calculations. Overall, these findings provide further insights on the interplay between defect modulation and carrier transport in metal oxides, which benefit the development of low-cost, highly-efficient solar energy conversion devices.Overcoming poor charge carrier transport represents one of the biggest challenges in the development of metal oxide photoelectrodes. Time-resolved conductivity measurements and density functional theory calculations reveal that a simple postsynthesis hydrogen treatment at 300 °C reduces the number of deep trap states in metal oxides. As a result, the charge carrier lifetime and overall photoelectrochemical performance are significantly enhanced.
      PubDate: 2017-08-25T04:33:11.653955-05:
      DOI: 10.1002/aenm.201701536
  • A Silicon Ratchet to Produce Power from Below-Bandgap Photons
    • Authors: Bryan Lau; Ofer Kedem, Mohamad Kodaimati, Mark A. Ratner, Emily A. Weiss
      Abstract: This paper computationally demonstrates a new photovoltaic mechanism that generates power from incoherent, below-bandgap (THz) excitations of conduction band electrons in silicon. A periodic sawtooth potential, realized through elastic strain gradients along a 100 nm thick Si slab, biases the oscillatory motion of excited electrons, which preferentially jump and relax into the adjacent period on the right to generate a net current. The magnitude of the ratchet current increases with photon energy (20, 50, and 100 meV) and irradiance (≈MW cm−2), which control the probability of photon scattering, and peaks as a function of the well depth of the ratchet potential, and the dominant mode of energy loss (the 62 meV intervalley phonon). The internal power conversion efficiency of the ratchet has a maximum of 0.0083% at a photon energy of 100 meV, due to inefficiencies caused by isotropic scattering. This new photovoltaic mechanism uses wasted below-bandgap absorptions to enhance the directional diffusion of charge carriers and could be used to augment the efficiency of traditional photovoltaics.A new intraband photovoltaic scheme based on silicon is presented. An asymmetric, periodic “ratchet” potential rectifies intraband excitations of electrons in the conduction band. Unlike previous examples of light-powered ratchets, this work uses incoherent, unpolarized THz radiation, which opens the possibility of using this new intraband photovoltaic mechanism to enhance traditional photovoltaics.
      PubDate: 2017-08-22T11:46:48.324326-05:
      DOI: 10.1002/aenm.201701000
  • A High-Volumetric-Capacity Cathode Based on Interconnected Close-Packed
           N-Doped Porous Carbon Nanospheres for Long-Life Lithium–Sulfur Batteries
    • Authors: Cheng Hu; Caroline Kirk, Qiong Cai, Carlos Cuadrado-Collados, Joaquín Silvestre-Albero, Francisco Rodríguez-Reinoso, Mark James Biggs
      Abstract: This study reports a Li–S battery cathode of high volumetric capacity enabled by novel micro- and mesostructuring. The cathode is based on monodisperse highly porous carbon nanospheres derived from a facile template- and surfactant-free method. At the mesoscale, the nanospheres structure into interconnected close-packed clusters of a few microns in extent, thus facilitating the fabrication of dense crack-free high areal sulfur loading (5 mg cm−2) cathodes with high electrical conductivity and low cathode impedance. A combination of the nitrogen doping (5 wt%), high porosity (2.3 cm3 g−1), and surface area (2900 m2 g−1) at the microscale enables high sulfur immobilization and utilization. The cathode delivers among the best reported volumetric capacity to date, above typical Li-ion areal capacity at 0.2 C over 200 cycles and low capacity fading of 0.1% per cycle at 0.5 C over 500 cycles. The compact cathode structure also ensures a low electrolyte requirement (6 µL mg−1), which aids a low overall cell weight, and further, among the best gravimetric capacities published to date as well.Li–S battery cathodes providing among the best volumetric/gravimetric capacities reported to date are prepared using interconnected close-packed N-doped carbon nanospheres of high surface area and porosity. The novel close-packed mesostructure and N-doped highly porous microstructure enable simultaneously high sulfur density and utilization, excellent electrochemical impedance, long cycle-life, and low electrolyte fraction, which all-together leads to the outstanding volumetric/gravimetric capacities.
      PubDate: 2017-08-21T03:16:41.393411-05:
      DOI: 10.1002/aenm.201701082
  • Nanoscale Morphology of Doctor Bladed versus Spin-Coated Organic
           Photovoltaic Films
    • Authors: Balaji Sesha Sarath Pokuri; Joseph Sit, Olga Wodo, Derya Baran, Tayebeh Ameri, Christoph J. Brabec, Adam J. Moule, Baskar Ganapathysubramanian
      Abstract: Recent advances in efficiency of organic photovoltaics are driven by judicious selection of processing conditions that result in a “desired” morphology. An important theme of morphology research is quantifying the effect of processing conditions on morphology and relating it to device efficiency. State-of-the-art morphology quantification methods provide film-averaged or 2D-projected features that only indirectly correlate with performance, making causal reasoning nontrivial. Accessing the 3D distribution of material, however, provides a means of directly mapping processing to performance. In this paper, two recently developed techniques are integrated—reconstruction of 3D morphology and subsequent conversion into intuitive morphology descriptors —to comprehensively image and quantify morphology. These techniques are applied on films generated by doctor blading and spin coating, additionally investigating the effect of thermal annealing. It is found that morphology of all samples exhibits very high connectivity to electrodes. Not surprisingly, thermal annealing consistently increases the average domain size in the samples, aiding exciton generation. Furthermore, annealing also improves the balance of interfaces, enhancing exciton dissociation. A comparison of morphology descriptors impacting each stage of photophysics (exciton generation, dissociation, and charge transport) reveals that spin-annealed sample exhibits superior morphology-based performance indicators. This suggests substantial room for improvement of blade-based methods (process optimization) for morphology tuning to enhance performance of large area devices.For optimizing the performance of organic photovoltaics, it is important to access the 3D distribution of material. This work integrates two recently developed techniques—reconstruction of 3D morphology and its conversion into intuitive morphology descriptors—to comprehensively image and quantify 3D morphology under spin-coating and doctor-blading processing conditions. The results suggest substantial room for improvement of blade-based methods.
      PubDate: 2017-08-17T03:11:29.006935-05:
      DOI: 10.1002/aenm.201701269
  • Correlating Electrode–Electrolyte Interface and Battery Performance in
           Hybrid Solid Polymer Electrolyte-Based Lithium Metal Batteries
    • Authors: Qiwei Pan; Dmitri Barbash, Derrick M. Smith, Hao Qi, Sarah E. Gleeson, Christopher Y. Li
      Abstract: Solid polymer electrolytes (SPEs) are desirable in lithium metal batteries (LMBs) since they are nonflammable and show excellent lithium dendrite growth resistance. However, fabricating high performance polymer LMBs is still a grand challenge because of the complex battery system. In this work, a series of tailor-designed hybrid SPEs are used to prepare LMBs with a LiFePO4-based cathode. High performance LMBs with both excellent rate capability and long cycle life are obtained at 60 and 90 °C. The well-controlled network structure in this series of hybrid SPEs offers a model system to study the relationship between the SPE properties and the LMB performance. It is shown that the cycle life of the polymer LMBs is closely correlated with the SPE–Li interface ionic conductivity, underscoring the importance of the solid electrolyte interface in LMB operation. LMB performance is further correlated with the molecular network structure. It is anticipated that results from this study will shed light on designing SPEs for high performance LMB applications.High performance lithium (Li) metal batteries with both high rate capability and long cycle life can be obtained at 90 and 60 °C by using cross-linked solid polymer electrolytes. For the first time, the cycle life of the polymer lithium metal batteries is directly correlated to the ionic conductivity of the Li–solid polymer electrolyte interface.
      PubDate: 2017-08-15T04:36:10.513383-05:
      DOI: 10.1002/aenm.201701231
  • Interfaces in Perovskite Solar Cells
    • Authors: Azhar Fakharuddin; Lukas Schmidt-Mende, Germà Garcia-Belmonte, Rajan Jose, Ivan Mora-Sero
      Abstract: Rapid improvement in photoconversion efficiency (PCE) of solution processable organometallic hybrid halide based perovskite solar cells (PSCs) have taken the photovoltaic (PV) community with a surprise and has extended their application in other electronic devices such as light emitting diodes, photo detectors and batteries. Together with efforts to push the PCE of PSCs to record values >22% – now at par with that of crystalline silicon solar cells – origin of their PV action and underlying physical processes are also deeply investigated worldwide in diverse device configurations. A typical PSC consists of a perovskite film sandwiched between an electron and a hole selective contact thereby creating ESC/perovskite and perovskite/HSC interfaces, respectively. The selective contacts and their interfaces determine properties of perovskite layer and also control the performance, origin of PV action, open circuit voltage, device stability, and hysteresis in PSCs. Herein, we define ideal charge selective contacts, and provide an overview on how the choice of interfacing materials impacts charge accumulation, transport, transfer/recombination, band-alignment, and electrical stability in PSCs. We then discuss device related considerations such as morphology of the selective contacts (planar or mesoporous), energetics and electrical properties (insulating and conducting), and its chemical properties (organic vs inorganic). Finally, the outlook highlights key challenges and future directions for a commercially viable perovskite based PV technology.The past few years marked a new era of organometallic halide hybrid perovskite efficient solar cell technology. To capitalize the potential of this new class of materials in solar cells, in particular, and in any electronic devices in general, an understanding of interfacial physical processes is crucial. Herein, a comprehensive analysis of the role of interfaces in determining the PV performance and long term operational stability of this PV technology is provided.
      PubDate: 2017-08-11T06:00:20.273276-05:
      DOI: 10.1002/aenm.201700623
  • High Energy and High Power Lithium-Ion Capacitors Based on Boron and
           Nitrogen Dual-Doped 3D Carbon Nanofibers as Both Cathode and Anode
    • Authors: Qiuying Xia; Hai Yang, Min Wang, Mei Yang, Qiubo Guo, Liming Wan, Hui Xia, Yan Yu
      Abstract: High energy density at high power density is still a challenge for the current Li-ion capacitors (LICs) due to the mismatch of charge-storage capacity and electrode kinetics between capacitor-type cathode and battery-type anode. In this work, B and N dual-doped 3D porous carbon nanofibers are prepared through a facile method as both capacitor-type cathode and battery-type anode for LICs. The B and N dual doping has profound effect in tuning the porosity, functional groups, and electrical conductivity for the porous carbon nanofibers. With rational design, the developed B and N dual-doped carbon nanofibers (BNC) exhibit greatly improved electrochemical performance as both cathode and anode for LICs, which greatly alleviates the mismatch between the two electrodes. For the first time, a 4.5 V “dual carbon” BNC//BNC LIC device is constructed and demonstrated, exhibiting outstanding energy density and power capability compared to previously reported LICs with other configurations. In specific, the present BNC//BNC LIC device can deliver a large energy density of 220 W h kg−1 and a high power density of 22.5 kW kg−1 (at 104 W h kg−1) with reasonably good cycling stability (≈81% retention after 5000 cycles).Boron and nitrogen dual-doped 3D porous carbon nanofibers (BNC) are prepared by a facile and controllable method for lithium-ion capacitors (LICs). With rational design, the B and N dual doping results in improved electrochemical performance of the carbon fibers as both cathode and anode. A “dual carbon” BNC//BNC LIC device is constructed with outstanding energy density and power capability.
      PubDate: 2017-08-09T02:46:28.358158-05:
      DOI: 10.1002/aenm.201701336
  • Molecularly Stacking Manganese Dioxide/Titanium Carbide Sheets to Produce
           Highly Flexible and Conductive Film Electrodes with Improved
           Pseudocapacitive Performances
    • Authors: Weihong Liu; Zhiqiang Wang, Yanli Su, Qingwen Li, Zhigang Zhao, Fengxia Geng
      Abstract: 2D nanostructures with high surface area and flexibility are regarded as a promising building platform for flexible supercapacitors that are attracting tremendous attention due to their potential applications in various wearable technologies. Notably, although pseudocapacitive metal oxides are widely accepted as a very important class of electrochemically active materials, the utilization of 2D metal oxide sheets in the preparation of flexible supercapacitors is very rare. The scarcity of a suitable filler with the integrated properties of both high conductivity and excellent hydrophilicity is probably to blame. In this work, by introducing a recently discovered intriguing material, Ti3C2 sheets, a novel MnO2/Ti3C2 hybrid with a molecularly stacked structure is developed using a simple and scalable mixing and filtration method. Their individual advantages are combined in the hybrid, thus delivering excellent electrochemical performances. A highly flexible and symmetric supercapacitor based on the novel hybrid electrode manifests top-class electrochemical performance with maximum energy and power densities of 8.3 W h kg−1 (at 221.33 W kg−1) and 2376 W kg−1 (at 3.3 W h kg−1), respectively, regardless of the various bending states, suggesting enormous possibilities for applications in future flexible and portable micropower systems.A manganese dioxide/titanium carbide hybrid film with two kinds of sheets molecularly stacked is successfully prepared by a simple and scalable vacuum filtration method. Such molecular hybridization integrates the best properties of the two ingredients and enables delivery of excellent electrochemical performances and also high mechanical flexibility.
      PubDate: 2017-08-08T07:00:52.779191-05:
      DOI: 10.1002/aenm.201602834
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