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  Subjects -> ENGINEERING (Total: 2246 journals)
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ENGINEERING (1191 journals)            First | 1 2 3 4 5 6 | Last

Showing 1001 - 1200 of 1205 Journals sorted alphabetically
Quality and Reliability Engineering International     Hybrid Journal   (Followers: 11)
Quality Engineering     Hybrid Journal   (Followers: 9)
Radiochimica Acta     Hybrid Journal   (Followers: 5)
Rapid Prototyping Journal     Hybrid Journal   (Followers: 2)
Rare Metals     Hybrid Journal  
Reactive and Functional Polymers     Hybrid Journal   (Followers: 5)
Recent Patents on Engineering     Full-text available via subscription   (Followers: 3)
Recent Patents on Nanotechnology     Full-text available via subscription   (Followers: 2)
Recherche Transports Sécurité     Hybrid Journal   (Followers: 1)
Redes de Ingeniería     Open Access  
Regional Maritime University Journal     Full-text available via subscription   (Followers: 2)
Regular and Chaotic Dynamics     Hybrid Journal  
Rem : Revista Escola de Minas     Open Access   (Followers: 1)
Remote Sensing     Open Access   (Followers: 32)
Remote Sensing Letters     Hybrid Journal   (Followers: 33)
Requirements Engineering     Hybrid Journal   (Followers: 3)
Research Ideas and Outcomes     Open Access  
Research in Engineering Design     Hybrid Journal   (Followers: 10)
Research Journal of Nanoscience and Nanotechnology     Open Access   (Followers: 2)
Research Works of Air Force Institute of Technology     Open Access   (Followers: 1)
Resonance     Hybrid Journal   (Followers: 23)
Reviews in Advanced Sciences and Engineering     Partially Free   (Followers: 2)
Revista AIDIS de Ingeniería y Ciencias Ambientales. Investigación, desarrollo y práctica     Open Access  
Revista Brasileira de Engenharia Agrícola e Ambiental     Open Access   (Followers: 1)
Revista Ciencias e Ingeniería al Día     Open Access  
Revista CINTEX     Open Access  
Revista Cubana de Ingeniería     Open Access  
Revista de Engenharia da Universidade Católica de Petrópolis     Open Access  
Revista de Ingeniería     Open Access  
Revista de Ingenieria Sismica     Open Access  
Revista EIA     Open Access   (Followers: 1)
Revista Facultad de Ingenieria - Universidad de Tarapaca     Open Access  
Revista Facultad de Ingeniería Universidad de Antioquia     Open Access   (Followers: 1)
Revista Iberoamericana de Automática e Informática Industrial RIAI     Open Access  
Revista Informador Técnico     Open Access   (Followers: 1)
Revista Ingenieria de Construcción     Open Access  
Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería     Open Access  
Revista Logos Ciencia & Tecnología     Open Access  
Revista Petra     Open Access  
Revue de Métallurgie     Full-text available via subscription  
Russian Engineering Research     Hybrid Journal  
Russian Journal of Non-Ferrous Metals     Hybrid Journal   (Followers: 25)
Russian Microelectronics     Hybrid Journal   (Followers: 1)
Sadhana     Open Access   (Followers: 6)
Safety Science     Hybrid Journal   (Followers: 19)
Scholedge International Journal of Multidisciplinary & Allied Studies     Open Access   (Followers: 2)
Science & Technique     Open Access  
Science and Engineering Ethics     Hybrid Journal   (Followers: 6)
Science and Technology     Open Access   (Followers: 2)
Science China Technological Sciences     Hybrid Journal  
Science Journal of Volgograd State University. Technology and innovations     Open Access  
Science Progress     Full-text available via subscription   (Followers: 3)
Scientia cum Industria     Open Access  
Scientific Journal of Control Engineering     Open Access   (Followers: 1)
Scientific Journal of Review     Open Access  
Sealing Technology     Full-text available via subscription   (Followers: 1)
Securitas Vialis     Hybrid Journal  
Security and Communication Networks     Hybrid Journal   (Followers: 3)
Selcuk University Journal of Engineering, Science and Technology     Open Access   (Followers: 1)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 42)
Semiconductors     Hybrid Journal  
Semiconductors and Semimetals     Full-text available via subscription  
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 1)
Sensor Letters     Full-text available via subscription   (Followers: 1)
Sensors     Open Access   (Followers: 13)
Separation and Purification Technology     Hybrid Journal   (Followers: 10)
Services Computing, IEEE Transactions on     Hybrid Journal   (Followers: 4)
Shock and Vibration     Hybrid Journal   (Followers: 8)
SIAM Journal on Applied Dynamical Systems     Hybrid Journal   (Followers: 2)
SIAM Journal on Mathematical Analysis     Hybrid Journal   (Followers: 3)
SIAM Journal on Matrix Analysis and Applications     Hybrid Journal   (Followers: 1)
SIAM Journal on Numerical Analysis     Hybrid Journal   (Followers: 4)
SIAM Journal on Optimization     Hybrid Journal   (Followers: 8)
SIAM Review     Hybrid Journal   (Followers: 6)
SILICON     Hybrid Journal  
Sistemas & Telemática     Open Access   (Followers: 1)
Sleep and Biological Rhythms     Hybrid Journal   (Followers: 4)
Small     Hybrid Journal   (Followers: 10)
Smart Grid     Open Access  
Soft Computing     Hybrid Journal   (Followers: 7)
Software Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 52)
Soil Dynamics and Earthquake Engineering     Hybrid Journal   (Followers: 12)
Soldagem & Inspeção     Open Access  
Solid-State Circuits Magazine, IEEE     Hybrid Journal   (Followers: 9)
SourceOCDE Developpement urbain, rural et regional     Full-text available via subscription   (Followers: 1)
SourceOCDE Energie     Full-text available via subscription  
SourceOECD Energy     Full-text available via subscription  
SourceOECD Science and Technology Statistics - SourceOCDE Base de donnees des sciences et de la technologie     Full-text available via subscription  
SourceOECD Transport     Full-text available via subscription   (Followers: 3)
SourceOECD Urban, Rural and Regional Development     Full-text available via subscription   (Followers: 1)
South African Computer Journal     Full-text available via subscription  
South African Journal of Agricultural Extension     Open Access   (Followers: 4)
South African Journal of Science     Open Access   (Followers: 3)
Sports Engineering     Hybrid Journal   (Followers: 3)
Stahlbau     Hybrid Journal   (Followers: 4)
Steel in Translation     Hybrid Journal  
Steel Research International     Hybrid Journal   (Followers: 27)
Stochastic Analysis and Applications     Hybrid Journal   (Followers: 2)
Stochastic Processes and their Applications     Hybrid Journal   (Followers: 5)
Stochastics and Dynamics     Hybrid Journal  
Strain     Hybrid Journal   (Followers: 2)
Strategic Planning for Energy and the Environment     Hybrid Journal   (Followers: 4)
Studies in Engineering and Technology     Open Access  
Studies in Interface Science     Full-text available via subscription   (Followers: 1)
Studies in Logic and Practical Reasoning     Full-text available via subscription  
Studies in Surface Science and Catalysis     Full-text available via subscription   (Followers: 1)
Superconductor Science and Technology     Hybrid Journal   (Followers: 2)
Surface Engineering     Hybrid Journal   (Followers: 3)
Surface Review and Letters     Hybrid Journal   (Followers: 1)
Surface Science Reports     Full-text available via subscription   (Followers: 15)
Survey Review     Hybrid Journal   (Followers: 6)
Surveying and Land Information Science     Full-text available via subscription   (Followers: 2)
Sustainability Science     Hybrid Journal   (Followers: 7)
Sustainability Science and Engineering     Full-text available via subscription   (Followers: 4)
Sustainable Management of Sediment Resources     Full-text available via subscription  
Swiss Journal of Geosciences     Hybrid Journal  
Symmetry     Open Access  
Synthesis Lectures on Algorithms and Software in Engineering     Full-text available via subscription  
Synthesis Lectures on Antennas     Full-text available via subscription   (Followers: 5)
Synthesis Lectures on Biomedical Engineering     Full-text available via subscription  
Synthesis Lectures on Computational Electromagnetics     Full-text available via subscription   (Followers: 4)
Synthesis Lectures on Energy and the Environment: Technology, Science, and Society     Full-text available via subscription   (Followers: 2)
Synthesis Lectures on Engineering     Full-text available via subscription  
Synthesis Lectures on Global Engineering     Full-text available via subscription  
Synthesis Lectures on Professionalism and Career Advancement for Scientists and Engineers     Full-text available via subscription  
Synthetic Metals     Hybrid Journal   (Followers: 4)
Systems Engineering     Hybrid Journal   (Followers: 6)
Systems Engineering Procedia     Open Access  
Systems Research Forum     Hybrid Journal  
Systems Science & Control Engineering     Open Access   (Followers: 5)
Techno.Com     Open Access  
Technological Engineering     Open Access  
Technologies     Open Access   (Followers: 1)
TECHNOLOGY     Hybrid Journal  
Technology and Innovation     Full-text available via subscription   (Followers: 3)
Technology in Society     Hybrid Journal   (Followers: 4)
Technometrics     Full-text available via subscription   (Followers: 6)
Tecnologia, Ciencia, Educacion     Open Access   (Followers: 1)
Tecnura     Open Access  
Telecommunications Policy     Hybrid Journal   (Followers: 14)
Terahertz Science and Technology, IEEE Transactions on     Hybrid Journal   (Followers: 2)
Textile Science and Technology     Full-text available via subscription   (Followers: 3)
The Journal of Computational Multiphase Flows     Full-text available via subscription  
The Journal of Supercomputing     Hybrid Journal   (Followers: 1)
The Scientific World Journal     Open Access  
Theoretical and Computational Fluid Dynamics     Hybrid Journal   (Followers: 12)
Theoretical Issues in Ergonomics Science     Hybrid Journal   (Followers: 3)
Thermal Engineering     Hybrid Journal   (Followers: 5)
Tikrit Journal of Engineering Science     Open Access  
tm - Technisches Messen     Hybrid Journal   (Followers: 2)
Topics in Catalysis     Hybrid Journal   (Followers: 1)
Traffic Injury Prevention     Hybrid Journal   (Followers: 50)
TRANSACTIONS of the VŠB - Technical University of Ostrava, Safety Engineering Series     Open Access   (Followers: 1)
Transactions of Tianjin University     Full-text available via subscription  
Transport and Telecommunication Journal     Open Access   (Followers: 4)
Transport World Africa     Full-text available via subscription   (Followers: 3)
Transportation Research Record : Journal of the Transportation Research Board     Full-text available via subscription   (Followers: 33)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 5)
Trends in Applied Sciences Research     Open Access   (Followers: 1)
Tribology in Industry     Open Access   (Followers: 1)
Tribology International     Hybrid Journal   (Followers: 41)
Tribology Letters     Hybrid Journal   (Followers: 5)
Tribology Transactions     Hybrid Journal   (Followers: 33)
Tribotest     Hybrid Journal  
Tropical Science     Hybrid Journal   (Followers: 1)
Turkish Journal of Engineering and Environmental Sciences     Open Access   (Followers: 1)
Ultramicroscopy     Hybrid Journal   (Followers: 2)
Uludağ University Journal of The Faculty of Engineering     Open Access  
Universal Journal of Applied Science     Open Access   (Followers: 2)
Universal Journal of Engineering Science     Open Access   (Followers: 1)
Utilities Policy     Hybrid Journal   (Followers: 2)
Vacuum     Hybrid Journal   (Followers: 12)
Virtual and Physical Prototyping     Hybrid Journal   (Followers: 3)
Visualization in Engineering     Open Access  
Walailak Journal of Science and Technology     Open Access  
Waste and Biomass Valorization     Hybrid Journal   (Followers: 1)
Waste Management Series     Full-text available via subscription   (Followers: 2)
Waves in Random and Complex Media     Hybrid Journal  
Waves, Wavelets and Fractals     Open Access  
Wear     Hybrid Journal   (Followers: 28)
Welding in the World     Hybrid Journal   (Followers: 2)
West African Journal of Industrial and Academic Research     Open Access   (Followers: 1)
Women in Engineering Magazine, IEEE     Full-text available via subscription   (Followers: 10)
World Journal of Engineering     Full-text available via subscription   (Followers: 3)
World Journal of Engineering and Technology     Open Access  
World Journal of Environmental Engineering     Open Access   (Followers: 2)
World Pumps     Full-text available via subscription   (Followers: 2)
World Science and Technology     Full-text available via subscription   (Followers: 1)
ZDM     Hybrid Journal  
Zede Journal     Open Access  
Zeitschrift fur Energiewirtschaft     Hybrid Journal   (Followers: 1)

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Journal Cover Ionics
  [SJR: 0.486]   [H-I: 36]   [0 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1862-0760 - ISSN (Online) 0947-7047
   Published by Springer-Verlag Homepage  [2335 journals]
  • LiNi 0.5 Mn 1.5 O 4 hollow nano-micro hierarchical microspheres as
           advanced cathode for lithium ion batteries
    • Abstract: Abstract The high-voltage spinel-type LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for next-generation lithium ion batteries. In this study, hollow LNMO microspheres have been synthesized via co-precipitation method accompanied with high-temperature calcinations. The physical and electrochemical properties of the materials are characterized by x-ray diffraction (XRD), TGA, RAMAN, CV, scanning electron microscope (SEM), transmission electon microscopy (TEM), electrochemical impendence spectroscopy (EIS), and charge-discharge tests. The results prove that the microspheres combine hollow structures inward and own a cubic spinel structure with space group of Fd-3m, high crystallinity, and excellent electrochemical performances. With the short Li+ diffusion length and hollow structure, the hierarchical LNMO microspheres exhibit 138.2 and 108.5 mAh g−1 at 0.5 and 10 C, respectively. Excellent cycle stability is also demonstrated with more than 98.8 and 88.2 % capacity retention after 100 cycles at 1 and 10 C, respectively.
      PubDate: 2016-09-28
  • Perovskite-type (Ba 0.15 Sr 0.85 )(B 0.15 Co 0.85 )O 3 − δ (B = Ti,
           Nb) oxides: structural stability, oxygen nonstoichiometry, and oxygen
           sorption/desorption properties
    • Abstract: Abstract The perovskite-type Ba- and Ti/Nb-doped (Ba0.15Sr0.85)(B0.15Co0.85)O3 − δ (B = Ti, Nb) oxides were synthesized successfully by the solid-state reaction method. Crystal structure, elemental compositions, and oxygen nonstoichiometry of the as-synthesized (Ba0.15Sr0.85)(B0.15Co0.85)O3 − δ (B = Ti, Nb) oxides were investigated by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), inductively coupled plasma (ICP)-atomic emission spectrometry, thermogravimetry (TG), and iodometric titration. XRD results demonstrate that the as-obtained (Ba0.15Sr0.85)(B0.15Co0.85)O3 − δ (B = Ti, Nb) oxides possess purely cubic perovskite-type structures. The temperature-swing oxygen sorption/desorption properties of the as-synthesized (Ba0.15Sr0.85)(B0.15Co0.85)O3 − δ (B = Ti, Nb) perovskite-type oxides were studied by the dynamic TG. Results show that the structural stability of the co-doped (Ba0.15Sr0.85)(B0.15Co0.85)O3 − δ (B = Ti, Nb) oxides is improved greatly, and the high oxygen sorption capacity for the perovskite-type (Ba0.15Sr0.85)(B0.15Co0.85)O3 − δ (B = Ti, Nb) oxides is also obtained between 300 and 950 °C in air.
      PubDate: 2016-09-27
  • Investigation of Al-doping effects on the NaFe 0.5 Mn 0.5 O 2 cathode for
           Na-ion batteries
    • Abstract: Abstract P2-Na2/3MO2 materials have recently been investigated as promising high-capacity cathode hosts for Na-ion batteries. On the other hand, the Na-deficiency in these materials precludes a high energy density when coupled with Na-free anodes. As an alternative, O3-NaFeO2 and its various derivatives such as NaFe0.5Mn0.5O2 have been suggested and investigated. In this study, we dope Al in NaFe0.5Mn0.5O2 and investigate Al-doping effects on the electrochemical properties of the Na+ host. The Al-doped compound shows almost the same conductivity and diffusivity as the pristine structure. However, Al-doping enhances O3-P3 phase transition.
      PubDate: 2016-09-27
  • Efficient electrocatalysis of formic acid oxidation onto Pd-Cu/poly
           (2-methoxyaniline)-SDS nanocomposite film
    • Abstract: Abstract In this work, porous poly (2-methoxyaniline) film prepared in the presence of sodium dodecyl sulfate (P2MA-SDS) is used as a potent support for dispersion of bimetallic palladium-copper nanoparticles (Pd-Cu NPs) towards the electrooxidation of formic acid (HCOOH) in sulfuric acid solution. The Pd-Cu NPs are prepared through galvanic replacement reaction between PdII ions and Cu particles. The SEM, EDS, and electrochemical methods were used to characterize the prepared Pd-Cu NPs. The obtained results show that the Pd-Cu exhibited significantly high current density of HCOOH oxidation compared to other catalysts and utilization of Cu NPs enhances the electrocatalytic activity towards electrooxidation. The enhanced performance is related to the synergetic effect between Pd-Cu NPs and P2MA-SDS film. The effects of galvanic replacement time, potential sweep rates, and concentration of HCOOH on the catalytic activity of the electrocatalyst as well as long-term stability are investigated by the various electrochemical techniques.
      PubDate: 2016-09-27
  • Ionic conductivity, ionic transport and electrochemical characterizations
           of plastic crystal polymer electrolytes
    • Abstract: Abstract In this work, the plastic crystal polymer electrolytes (PCPEs), composed of polyacrylonitrile (PAN), succinonitrile (SN) and lithium bis(trifluoromethane)sulfonimide (LiTFSI) were prepared. The concentrations of lithium salt were varied by weight percentage from 10 wt% to 50 wt%. The ionic conductivity of the PCPE films increases with the increase of lithium salt, where the highest value recorded is in the order of ~10−2 S cm−1. The temperature-dependence conductivity analysis shows that the PCPE films exhibit Arrhenius behaviour when subjected to the temperature range from 303 K to 343 K. The decrease in crystallinity was confirmed by X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC) analyses. The cationic transport number also increases with the increase of salt which corresponds well to their conductivity values. It is found that the films are electrochemically stable up to ~3.6 V as revealed by the linear sweep voltammetry (LSV) analysis. The cyclic voltammetry (CV) plots of the films shown no substantial change in the redox peaks which mean that the charge transfer reaction is reversible.
      PubDate: 2016-09-27
  • The significance of the stable Rhombohedral structure in Li-rich cathodes
           for lithium-ion batteries
    • Abstract: Abstract The lithium-rich layered oxides offer higher capacity, but suffer from severe capacity fade and voltage decay. Aluminum doping can improve the stability of the structure, but the fundamental mechanism has not been fully revealed. In this work, cathode materials with different Al-doping contents are investigated. To characterize the structural evolutions upon cycling, ex situ XRD and ex situ TEM are performed. It is demonstrated that the voltage decay is attributed to the decrease of Rhombohedral phase, while capacity fade is possibly associated with the increase of surface impedance. Therefore, continuous voltage decay and capacity fade are observed for undoped Li-rich cathode. In comparison, the Al-doped cathodes have stable LiNi1/3Co1/3Mn1/3O2 and surface impedance, leading to superior capacity retention and a stable output voltage.
      PubDate: 2016-09-27
  • Effect of ionic liquid incarceration during free radical polymerization of
           PMMA on its structural and electrical properties
    • Abstract: Abstract The thin film of poly(methyl methacrylate) (PMMA) has been widely studied as host in a polymer electrolyte system due to its good mechanical stability towards lithium electrode. However, the brittle property of this film creates additional resistance for the ionic conduction. The addition of ionic liquid (IL) has been noticed to improve the brittleness of the film. In addition, its ionic conductivity can also be enhanced, but no free standing film can be obtained when higher amount of IL was added. Therefore, in this study, 1-methyl-3-pentamethyldisiloxymethylimidazolium bis(trifluoromethylsulfonyl)imide,[(SiOSi)C1C1im][NTf2], was incarcerated during free radical polymerization of MMA. Interestingly, this newly synthesized PMMA (PMMAIL) gives a flexible and transparent film with ionic conductivity of ∼10−7 S/cm at room temperature. The structural properties of this PMMAIL were further investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and optical microscope (OM).
      PubDate: 2016-09-23
  • Preparation and improvement in photovoltaic performance of dye-sensitized
           solar cells using carbon dioxide
    • Abstract: Abstract We report preparation and improvement in photovoltaic performance of N719-based dye-sensitized solar cells (DSSCs) using pressurized carbon dioxide (CO2) as a co-solvent for the absorption process on the TiO2 photoelectrode surface. Effective absorption of the N719 molecules on the TiO2 surface was achieved using CO2 processing, and the absorption time was shortened drastically from 24 h (in the dip process) to less than 3 h. The cells prepared under pressurized CO2 for the absorption showed greater photovoltaic performance, especially higher short-circuit current density and conversion efficiency, compared with that from typical dip method. It was revealed that the suitable CO2 pressure for the absorption was 5 MPa and the efficiency was achieved to be more than 7.5 %. Prevention of back electron transfer reactions from TiO2 to oxidized dyes or iodides was caused currently, because the homogeneous coverage of N719 molecules on the TiO2 surface was obtained by the use of pressurized CO2.
      PubDate: 2016-09-23
  • Effect of Ce-doped MnO 2 catalyst on the lithium-air batteryperformance in
           the ambient atmosphere
    • Abstract: Abstract MnO2 doped with Ce was hydrothermally synthesized and the as-made breathable waterproof membrane used outside the cathode was prepared for improving the lithium-air battery performance in air. The samples were characterized by scanning electron microscopy (SEM), energy dispersive spectrum analysis (EDS), charge–discharge cycle tests, charge–discharge cycle tests of limited capacity, and electrochemical impedance spectroscopy (EIS) tests. The result showed that Ce x Mn1-x O2 can effectively reduce the charge overpotential of the cathode. The charge and discharge electrical potential difference of Ce0.1Mn0.9O2 was only 700 mV while MnO2’s was 2100 mV. And Ce0.1Mn0.9O2 that exhibited high discharge capacity of 400 mAh g−1 in air had a stable discharge platform of 2.5 V and then the more obvious charge phenomenon appeared after 3.5 V. The excellent catalysis, the effect of cathode catalytic materials named Ce x Mn1-x O2, may attribute to the decrease of reaction potential energy of oxygen reduction reaction and oxygen evolution reaction.
      PubDate: 2016-09-23
  • In situ growth of ultrashort rice-like CuO nanorods supported on reduced
           graphene oxide nanosheets and their lithium storage performance
    • Abstract: Abstract A facile refluxing strategy in aqueous solution was engaged to synthesize ultrashort rice-like CuO nanorods/reduced graphene oxide (CuO-NRs/rGO) composite. The result of the high-resolution transmission electron microscopy shows that the as-synthesized rice-like CuO nanorods have a uniform size of about 8 nm in width and 28 nm in length and are homogenously dispersed on rGO nanosheets. The CuO nanorods are uniformly dispersed and immobilized by the graphene nanosheets reduced from GO. The resultant CuO-NRs/rGO composite as anode material for lithium-ion batteries displays better electrochemical properties than those of pure CuO-NRs and rGO nanosheets. The high reversible capacity and good stability can be ascribed to the presence of rGO nanosheets.
      PubDate: 2016-09-20
  • Advanced LiTi 2 (PO 4 ) 3 /C anode by incorporation of carbon nanotubes
           for aqueous lithium-ion batteries
    • Authors: Zhangxing He; Yifan Jiang; Dan Sun; Lei Dai; Haiyan Wang
      Abstract: Abstract Inferior rate capability is a big challenge for LiTi2(PO4)3 anode for aqueous lithium-ion batteries. Herein, to address such issue, we synthesized a high-performance LiTi2(PO4)3/carbon/carbon nanotube (LTP/C/CNT) composite by virtue of high-quality carbon coating and incorporation of good conductive network. The as-prepared LTP/C/CNT composite exhibits excellent rate performance with discharge capacity of 80.1 and 59.1 mAh g−1 at 10 C and 20 C (based on the mass of anode, 1 C = 150 mA g−1), much larger than that of the LTP/C composite (53.4 mAh g−1 at 10 C, and 31.7 mAh g−1 at 20 C). LTP/C/CNT also demonstrates outstanding cycling stability with capacity retention of 83.3 % after 1000 cycles at 5 C, superior to LTP/C without incorporation of CNTs (60.1 %). As verified, the excellent electrochemical performance of the LTP/C/CNT composite is attributed to the enhanced electrical conductivity, rapid charge transfer, and Li-ion diffusion because of the incorporation of CNTs.
      PubDate: 2016-09-20
      DOI: 10.1007/s11581-016-1828-5
  • Surface-modified Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 nanoparticles with
           LaF 3 as cathode for Li-ion battery
    • Abstract: Abstract The LaF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 nanoparticles were synthesized via co-precipitation method followed by simple chemical deposition process. The crystal structure, particle morphology, and electrochemical properties of the bare and coated materials were studied by XRD, SEM, TEM, charge–discharge tests. The results showed that the surface coating on Li[Li0.2Mn0.54Ni0.13Co0.13]O2 nanoparticles were amorphous LaF3 layer with a thickness of about 10–30 nm. After the surface modification with LaF3 films, the coating layer served as a protective layer to suppress the side reaction between the positive electrode and electrolyte, and the Li[Li0.2Mn0.54Ni0.13Co0.13]O2 oxide demonstrated the improved electrochemical properties. The LaF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 electrode delivered the capacities of 270.5, 247.9, 197.1, 170.0, 142.7, and 109.5 mAh g−1 at current rates of 0.1, 0.2, 0.5, 1, 2, and 5 C rate, respectively. Besides, the capacity retention was increased from 85.1 to 94.8 % after 100 cycles at 0.5 C rate. It implied surface modification with LaF3 played an important role to improve the cyclic stability and rate capacity of the Li-rich nickel manganese oxides.
      PubDate: 2016-09-19
      DOI: 10.1007/s11581-016-1823-x
  • Double-layer capacitance for a charged surface
    • Authors: Robert Warmbier; Nkosinathi Malaza; Alexander Quandt
      Abstract: Abstract Supercapacitors are a key technology for the energy storage requirements of future energy systems. A primary problem of supercapacitors is their limited energy density, but new electrode materials and electrode designs might help to overcome this limitation. Numerical modelling can be a valuable tool in this challenge, although realistic ab initio calculations are usually very cumbersome. In this work, we show that electric double-layer capacitors can be modelled to good accuracy by a coarse-grained sampling of the electrolyte’s configuration space rather than using full molecular dynamics simulations. This saves considerable computation time, and it allows for processing more materials and more complicated systems with modest computational effort.
      PubDate: 2016-09-17
      DOI: 10.1007/s11581-016-1813-z
  • Binder-free chemical synthesis of ZnFe 2 O 4 thin films for asymmetric
           supercapacitor with improved performance
    • Authors: Madagonda M. Vadiyar; Sanjay S. Kolekar; Nishad G. Deshpande; Jia-Yaw Chang; Anil A. Kashale; Anil V. Ghule
      Abstract: In this work, a simple, cost-effective, binder-free, and wet chemical successive ionic layer adsorption and reaction (SILAR) method is developed for the growth of ZnFe2O4 thin films on stainless steel substrate. The thin films were characterized using X-ray diffraction, scanning electron microscope, BET surface area analyzer, X-ray photoelectron spectroscopy, and electrochemical analyzer. The synthesized ZnFe2O4 thin films show excellent electrochemical properties by delivering maximum specific capacitance of 615 F g−1 at 3 mA cm−2 current density. The porous ZnFe2O4 thin film (SS/ZnFe2O4) is used as a negative electrode in combination with Mn3O4 (Mn3O4/SS, SILAR, positive electrode) for the fabrication of asymmetric supercapacitor device (SS/ZnFe2O4//Mn3O4/SS). The device shows maximum specific capacitance of 81 F g−1 and delivers a maximum energy density of 28 Wh kg−1 at 7.97 kW kg−1 power density with comparable cycle stability showing 74 % capacitance retention over 3000 cycles. Graphical abstract The ZnFe2O4 thin film deposited using SILAR method demonstrates specific capacitance of 615 F g−1, while the asymmetric device (SS/ZnFe2O4//Mn3O4/SS) delivers maximum energy density (28 Wh kg−1) and good cycle stability (74 % retention up to 3000 cycles).
      PubDate: 2016-09-17
      DOI: 10.1007/s11581-016-1833-8
  • Influence of sol-gel precursors on the electrochemical performance of NaMn
           0.33 Ni 0.33 Co 0.33 O 2 positive electrode for sodium-ion battery
    • Authors: Vijay Shankar Rangasamy; Savitha Thayumanasundaram; Jean-Pierre Locquet; Jin Won Seo
      Abstract: Abstract Among the various cathode materials explored for sodium-ion batteries (SIBs), NaMn0.33Ni0.33Co0.33O2, with a layered oxide structure, is a promising material due to its high theoretical capacity (240 mAhg−1). We have synthesized NaMn0.33Ni0.33Co0.33O2 using two different types of precursors, namely metal acetates and metal nitrates by the sol-gel method. XRD patterns confirm the formation of a stable phase of the material at 900 °C. Coupled TGA-FTIR analysis was used to optimize the calcination conditions and to understand the hydrolysis and condensation mechanism of the sol-gel precursors. FTIR spectra extracted at different temperatures reveal the polymer network-forming tendency of the acetate ligands whereas the polymerization is inhibited in the nitrate precursors. SEM analysis shows spherical and platelet morphologies of samples synthesized from nitrate and acetate precursors, respectively. Using in situ impedance and galvanostatic charge/discharge studies, we observed that the precursors used to synthesize the cathode material influence the electrochemical properties of the material, as in this case, where we observe a 20 % improvement in terms of capacity by using acetate precursors instead of nitrate precursors.
      PubDate: 2016-09-17
      DOI: 10.1007/s11581-016-1824-9
  • Nano-sized Co/Co(OH) 2 core-shell structure synthesized in molten salt as
           electrode materials for supercapacitors
    • Abstract: Abstract A facile and low cost molten salt method for the synthesis of Co@Co(OH)2 core-shell nanostructured material exhibiting high specific capacitances for supercapacitors was developed. In our conditions, the molten salt acted as solvent and reducing agent for the precipitation and formation of Co-based nano-structures. It was observed that in the Co@Co(OH)2 core-shell nanostructure, Co cores can act as a conductive medium to improve the utilization of Co(OH)2 due to the superior electrical conductivity of Co metal and its high surface area. It was also found that the as-prepared Co@Co(OH)2 exhibited high electrochemical performance as a cathode material in asymmetric supercapacitors, yielding specific capacitance values of up to ~410 F g−1 at 2 A g−1 with a retention rate of 90 % after 2500 cycles. The achievement of high capacitance coupled to a low cost method represents an important step forward in the development of promising electrode materials for alkaline supercapacitor cathodes.
      PubDate: 2016-09-15
  • Hierarchical porous ZnMn 2 O 4 synthesized by the sucrose-assisted
           combustion method for high-rate supercapacitors
    • Abstract: Abstract A simple sucrose-assisted combustion and subsequent high-temperature calcination route have been employed to prepare hierarchical porous ZnMn2O4 nanostructure. When used as an electrode for supercapacitor, the ZnMn2O4 electrode displays a high specific capacitance of 411.75 F g−1 at a current density of 1 A g−1, remarkable capacitance retention rate of 64.28 % at current density of 32 A g−1 compared with 1 A g−1, as well as excellent cycle stability (reversible capacity retention of 88.32 % after 4000 cycles). The outstanding electrochemical performances are mainly attributed to its hierarchical porous architecture, which provides large reaction surface area, fast ion and electron transfer, and good structure stability. All these impressive results demonstrate that ZnMn2O4 shows promise for its application in supercapacitors.
      PubDate: 2016-09-15
  • Synthesis and electrochemical performance of P2-Na 0.67 Al x Co 1-x O 2
           (0.0 ≤ × ≤ 0.5) nanopowders for sodium-ion capacitors
    • Abstract: Abstract Layered P2-Na0.67Al x Co 1-x O2 (0.0 ≤ × ≤ 0.5) nanopowders were prepared by solution combustion process. These nanopowders were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and field emission scanning electron microscopy (FE-SEM) analysis. The electrochemical behaviours of the prepared layered P2-Na0.67Al x Co 1-x O2 nanopowder-based electrodes were investigated by cyclic voltammetry, electrochemical impedances and galvanostatic charge-discharge studies in 1 M Na2SO4 solution. The layered P2-Na0.67Al0.3Co0.7O2 has achieved a high specific capacitance of 260 F g−1 at a constant current density of 1 A g−1. The excellent electrochemical performance of Na0.67Al0.3Co0.7O2 is due to the partial substitution of Al3+ ions for Co3+ ions that leads to decrease in lattice parameter, resulting in the better structural stability during the Na+ ion intercalation/deintercalation reaction process. Moreover, the Na0.67Al0.3Co0.7O2 demonstrates a long cycle life with 80.1 % of its specific capacitance retention even after 5000 continuous charge-discharge process at a constant current density of 1 A g−1.
      PubDate: 2016-09-15
  • Dielectric and AC conductivity studies in Li 2 O-CoO-B 2 O 3 -TeO 2
    • Abstract: CoO and Li2O mixed with borotellurite glasses in the compositions, (B2O3)0.2-(TeO2)0.3-(CoO) x -(Li2O)0.5−x, where x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, and 0.50 were synthesized by fast cooling the melt to room temperature. Absence of crystalline phases in the samples was confirmed by X-ray diffraction studies. Changes in dielectric properties with frequency and temperature over wide ranges have been measured. Dielectric constant and loss increased with increase in CoO content. AC conductivity has been analyzed using Mott’s small polaron model and activation energy was determined. Activation energy decreased and conductivity increased with increase in CoO content up to 0.3 mole fractions, and they behaved oppositely for higher concentration of CoO. This observed change of trend in activation energy and conductivity at 0.3 mole fraction of CoO ascribed to switch over of conduction mechanism occurring from predominantly ionic to electronic regime. For the first time, a transition of conduction mechanism is observed in borotellurite glasses. Temperature and composition independent relaxation mechanism in these glasses has been confirmed by plotting the scaled conductivity master curves. Hunt’s model has been invoked to understand the frequency dispersion of conductivity. Graphical abstract Plots of ln(ε′′) versus ln(F) for BTCL2 glass at different temperatures
      PubDate: 2016-09-13
  • Physicochemical properties of ionic liquid mixtures containing choline
           chloride, chromium (III) chloride and water: effects of temperature and
           water content
    • Authors: V. S. Protsenko; L. S. Bobrova; F. I. Danilov
      Abstract: Abstract The effects of water addition and temperature on some physicochemical properties of room temperature ionic liquids containing chromium chloride, choline chloride and water in the molar ratio of 1:2.5:x (where x = 6, 9, 12, 15 or 18) have been studied. The density, viscosity, surface tension and conductivity of the liquid mixtures were measured for the temperature range of 25 to 80 °C. Increasing both water content and temperature resulted in decreasing density, surface tension and viscosity and increasing electrical conductivity. The average void radii (hole sizes) for the liquid systems under study were calculated; they were in the range of 1.21 to 1.82 Å. The average hole size was stated to grow with increasing both temperature and water content in the mixture. The variation of the average void radii correlates with the change in viscosity and conductivity. The activation energies of viscous flow and conductivity diminishes with increasing water content in the liquid mixture. There is a strong linear correlation between conductivity and fluidity which indicates that the conductivity of the ionic liquid mixtures is generally controlled by the ionic mobility. A moderate viscosity and higher conductivity of the Cr(III)-containing ionic liquids with extra-water addition (at x > 9) make them suitable for the development of chromium electrodeposition processes.
      PubDate: 2016-09-10
      DOI: 10.1007/s11581-016-1826-7
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