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  Subjects -> ENGINEERING (Total: 2070 journals)
    - CHEMICAL ENGINEERING (171 journals)
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    - ELECTRICAL ENGINEERING (88 journals)
    - ENGINEERING (1148 journals)
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ENGINEERING (1148 journals)            First | 2 3 4 5 6 7 8 9 | Last

International Journal of Information Acquisition     Hybrid Journal   (Followers: 1)
International Journal of Innovation and Applied Studies     Open Access   (Followers: 2)
International Journal of Innovation Science     Full-text available via subscription   (Followers: 6)
International Journal of Integrated Engineering     Open Access   (Followers: 1)
International Journal of Intelligent Engineering Informatics     Hybrid Journal  
International Journal of Intelligent Systems and Applications in Engineering     Open Access  
International Journal of Lifecycle Performance Engineering     Hybrid Journal   (Followers: 1)
International Journal of Machine Tools and Manufacture     Hybrid Journal   (Followers: 5)
International Journal of Manufacturing Research     Hybrid Journal   (Followers: 5)
International Journal of Manufacturing Technology and Management     Hybrid Journal   (Followers: 7)
International Journal of Materials and Product Technology     Hybrid Journal   (Followers: 4)
International Journal of Mathematical Education in Science and Technology     Hybrid Journal   (Followers: 7)
International Journal of Mathematics in Operational Research     Hybrid Journal   (Followers: 1)
International Journal of Medical Engineering and Informatics     Hybrid Journal   (Followers: 5)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 4)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 1)
International Journal of Microwave Science and Technology     Open Access   (Followers: 2)
International Journal of Mobile Network Design and Innovation     Hybrid Journal   (Followers: 3)
International Journal of Multiphase Flow     Hybrid Journal   (Followers: 2)
International Journal of Nanomanufacturing     Hybrid Journal   (Followers: 1)
International Journal of Nanoscience     Hybrid Journal   (Followers: 1)
International Journal of Nanotechnology     Hybrid Journal   (Followers: 5)
International Journal of Nanotechnology and Molecular Computation     Full-text available via subscription   (Followers: 3)
International Journal of Navigation and Observation     Open Access   (Followers: 6)
International Journal of Network Management     Hybrid Journal  
International Journal of Nonlinear Sciences and Numerical Simulation     Full-text available via subscription  
International Journal of Numerical Methods for Heat & Fluid Flow     Hybrid Journal   (Followers: 7)
International Journal of Optics     Open Access   (Followers: 1)
International Journal of Organisational Design and Engineering     Hybrid Journal   (Followers: 9)
International Journal of Pattern Recognition and Artificial Intelligence     Hybrid Journal   (Followers: 6)
International Journal of Pavement Engineering     Hybrid Journal   (Followers: 2)
International Journal of Physical Modelling in Geotechnics     Hybrid Journal   (Followers: 3)
International Journal of Plasticity     Hybrid Journal   (Followers: 6)
International Journal of Plastics Technology     Hybrid Journal  
International Journal of Polymer Analysis and Characterization     Hybrid Journal   (Followers: 5)
International Journal of Polymer Science     Open Access   (Followers: 16)
International Journal of Precision Engineering and Manufacturing     Hybrid Journal   (Followers: 5)
International Journal of Precision Engineering and Manufacturing-Green Technology     Hybrid Journal  
International Journal of Precision Technology     Hybrid Journal  
International Journal of Pressure Vessels and Piping     Hybrid Journal   (Followers: 3)
International Journal of Production Economics     Hybrid Journal   (Followers: 13)
International Journal of Quality and Innovation     Hybrid Journal   (Followers: 4)
International Journal of Quality Assurance in Engineering and Technology Education     Full-text available via subscription   (Followers: 2)
International Journal of Quality Engineering and Technology     Hybrid Journal   (Followers: 2)
International Journal of Quantum Information     Hybrid Journal  
International Journal of Rapid Manufacturing     Hybrid Journal   (Followers: 1)
International Journal of Reliability, Quality and Safety Engineering     Hybrid Journal   (Followers: 6)
International Journal of Renewable Energy Technology     Hybrid Journal   (Followers: 8)
International Journal of Robust and Nonlinear Control     Hybrid Journal   (Followers: 2)
International Journal of Science Engineering and Advance Technology     Open Access  
International Journal of Sediment Research     Full-text available via subscription   (Followers: 1)
International Journal of Self-Propagating High-Temperature Synthesis     Hybrid Journal   (Followers: 2)
International Journal of Signal and Imaging Systems Engineering     Hybrid Journal  
International Journal of Six Sigma and Competitive Advantage     Hybrid Journal  
International Journal of Social Robotics     Hybrid Journal   (Followers: 2)
International Journal of Software Engineering and Knowledge Engineering     Hybrid Journal   (Followers: 1)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 2)
International Journal of Speech Technology     Hybrid Journal   (Followers: 4)
International Journal of Spray and Combustion Dynamics     Full-text available via subscription   (Followers: 6)
International Journal of Surface Engineering and Interdisciplinary Materials Science     Full-text available via subscription   (Followers: 1)
International Journal of Surface Science and Engineering     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Engineering     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Manufacturing     Hybrid Journal   (Followers: 4)
International Journal of Systems and Service-Oriented Engineering     Full-text available via subscription  
International Journal of Systems Assurance Engineering and Management     Hybrid Journal  
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 2)
International Journal of Technoethics     Full-text available via subscription  
International Journal of Technology Management and Sustainable Development     Hybrid Journal   (Followers: 1)
International Journal of Technology Policy and Law     Hybrid Journal   (Followers: 4)
International Journal of Telemedicine and Applications     Open Access   (Followers: 2)
International Journal of Thermal Sciences     Hybrid Journal   (Followers: 7)
International Journal of Thermodynamics     Open Access   (Followers: 2)
International Journal of Turbo & Jet-Engines     Full-text available via subscription  
International Journal of Ultra Wideband Communications and Systems     Hybrid Journal  
International Journal of Vehicle Autonomous Systems     Hybrid Journal   (Followers: 1)
International Journal of Vehicle Design     Hybrid Journal   (Followers: 6)
International Journal of Vehicle Information and Communication Systems     Hybrid Journal   (Followers: 2)
International Journal of Vehicle Noise and Vibration     Hybrid Journal   (Followers: 3)
International Journal of Vehicle Safety     Hybrid Journal   (Followers: 5)
International Journal of Vehicular Technology     Open Access   (Followers: 2)
International Journal of Virtual Technology and Multimedia     Hybrid Journal   (Followers: 4)
International Journal of Wavelets, Multiresolution and Information Processing     Hybrid Journal  
International Journal on Artificial Intelligence Tools     Hybrid Journal   (Followers: 4)
International Nano Letters     Open Access   (Followers: 9)
International Review of Applied Sciences and Engineering     Full-text available via subscription  
Inverse Problems in Science and Engineering     Hybrid Journal   (Followers: 2)
Ionics     Hybrid Journal  
IPTEK The Journal for Technology and Science     Open Access  
IRBM News     Full-text available via subscription  
Irrigation and Drainage Systems     Hybrid Journal  
ISA Transactions     Full-text available via subscription   (Followers: 1)
ISRN - International Scholarly Research Notices     Open Access   (Followers: 68)
ISRN Nanotechnology     Open Access  
ISRN Signal Processing     Open Access   (Followers: 1)
ISRN Thermodynamics     Open Access  
IT Professional     Full-text available via subscription   (Followers: 3)
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 2)
Journal of Advanced Manufacturing Systems     Hybrid Journal   (Followers: 5)
Journal of Aerosol Science     Hybrid Journal   (Followers: 1)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 195)

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Journal Cover   Ionics
  [SJR: 0.522]   [H-I: 25]   Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1862-0760 - ISSN (Online) 0947-7047
   Published by Springer-Verlag Homepage  [2300 journals]
  • Characterization and performance of cobalt-free perovskite-type La 0.6 Ba
           0.4 Fe 0.8 Ni 0.2 O 3 − δ cathode material for
           intermediate-temperature solid oxide fuel cells
    • Abstract: Abstract A novel cobalt-free perovskite La0.6Ba0.4Fe0.8Ni0.2O3 − δ (LBFN) powder was synthesized using a combustion method. The phase composition, electrical conductivity, thermal expansion coefficient (TEC), and electrochemical properties of LBFN were systematically investigated. The X-ray diffraction (XRD) results revealed that LBFN had a high chemical compatibility with Ce0.8Sm0.2O2 − δ (SDC). The LBFN cathode exhibited a competitive electrode area-specific resistance (ASR) for the symmetric cell based on SDC electrolyte. Furthermore, the electrochemical performance of LBFN cathode could be effectively improved with the addition of the proper amount of SDC. Using the LBFN–SDC73 (7:3 in weight ratio) as a composite cathode, the Ni–SDC-supported single cell with a 25-μm-thick SDC electrolyte exhibited maximum power densities of 330, 216, and 119 mW cm−2 at 600, 550, and 500 °C, respectively.
      PubDate: 2015-03-04
       
  • Synthesis of graphene oxide nanosheets and its application to construct a
           
    • Abstract: Abstract A ferrocene-derivative compound, 2, 7-bis (ferrocenyl ethynyl) fluoren-9-one (2,7-BFE), was synthesized and used to construct a modified graphene paste electrode. The electrooxidation of hydroxylamine at the surface of the modified electrode was studied using cyclic voltammetry (CV), chronoamperometry (CHA), and square wave voltammetry (SWV). Under the optimized conditions, the square wave voltammetric peak current of hydroxylamine increased linearly with hydroxylamine concentration in the range of 2.0 × 10−7 to 2.5 × 10−4 M and detection limit of 9.0 × 10−8 M was obtained for hydroxylamine. Finally, this modified electrode was used for determination of hydroxylamine in some water samples.
      PubDate: 2015-03-04
       
  • The optimal condition for H 2 TiO 3 –lithium adsorbent preparation
           and Li + adsorption confirmed by an orthogonal test design
    • Abstract: Abstract An orthogonal test design was applied to confirm the optimum condition for H2TiO3–lithium adsorbent preparation and Li+ adsorption. Extraction and adsorption mechanism and cycle performance were studied. The verified optimal condition is confirmed as the Li+ concentration, adsorption temperature, molar ratio of Li/Ti, reaction, and pre-calcination temperature are 4.0 g L−1, 60 °C, 2.2, and 650 and 25 °C, respectively. Under the optimal condition, the adsorptive capacity reaches 57.8 mg g−1. Adsorptive capacity of the adsorbent maintains in 5 cycles, typically 25–30 mg g−1.
      PubDate: 2015-03-03
       
  • Electrochemical performance of LiMnPO 4 by Fe and Zn co-doping for
           lithium-ion batteries
    • Abstract: Abstract To study the effect of Fe and/or Zn doping on the performance of LiMnPO4, LiMn0.9Fe0.1−x Zn x PO4/C (x = 0, 0.05, and 0.1) composites were synthesized by a solid-state process. They are all single phase with olivine structure but LiMn0.9(FeZn)0.05PO4/C reveals a different morphology. The Fe-Zn co-doping remarkably enhances the performance of LiMnPO4 due to the presence of Fe and Zn in olivine framework resulting in the decrease of charge transfer resistance and Mn ion dissolution. Compared with LiMn0.9Fe0.1PO4/C and LiMn0.9Zn0.1PO4/C, LiMn0.9(FeZn)0.05PO4/C exhibits much higher discharge capacity and better rate capability. It delivers the capacities of 151.3 mAh g−1 at 0.1 C and 128.4 mAh g−1 at 1 C and retains 96.7 % of the initial capacity after 100 cycles.
      PubDate: 2015-03-01
       
  • Low-temperature co-sintering of co-ionic conducting solid oxide fuel cells
           
    • Abstract: Abstract A composite electrolyte Ce0.8Sm0.2O1.9-BaCe0.8Sm0.2O2.9 (SDC-BCS) material for co-ionic conducting solid oxide fuel cells was prepared by microwave-assisted sol-gel technique. The crystallization, morphology, and sintering characteristics were investigated by X-ray diffraction and scanning electron microscopy. The obtained SDC-BCS composite electrolyte powders distribute uniformly, and SDC and BCS crystalline grains play a role as matrix for each other in the composite electrolyte. Anode-supported solid oxide fuel cells of NiO-Ce0.8Sm0.2O1.9/Ce0.8Sm0.2O1.9-BaCe0.8Sm0.2O2.9/Ce0.8Sm0.2O1.9-SrCo0.9Ti0.1O2.55 (NiO-SDC/SDC-BCS/SDC-SCT) were fabricated based on the nanocomposite electrolyte powders. The electrochemical performances were tested at 500–650 °C using humidified hydrogen as fuel. Results demonstrated that the anode-supported half cells could be sintered at 1,300 °C with a dense electrolyte layer and a porous anode structure. Moreover, the single cell with 40-μm-thick electrolyte layer achieved an open-circuit voltage (OCV) of 0.77 V and a maximum power density of 621 mW cm−2 at 650 °C.
      PubDate: 2015-03-01
       
  • Improvement of BaCe 0.8 Sm 0.1 Y 0.1 O 3-δ -based IT-SOFC by
           optimizing spin-coated process of cathode and sintering temperature
    • Abstract: Abstract Proton-conducting electrolyte with Sm and Y co-doped BaCeO3 (BaCe0.8Sm0.1Y0.1O3-δ, BCSY) were prepared by sol–gel combustion method. The characterization of proton-conducting electrolyte was evaluated in saturated humidity by structure identification, such as X-ray diffraction (XRD). Anode-supported cell with configuration of Ni-BCSY/BCSY/SSC (Sm0.5Sr0.5CoO3-δ) were fabricated. The cell with cathode after two coats and sintering temperature of 1,050 °C showed superior electrical performance. It was achieved with open circuit voltage (OCV) of 0.99 V and P max of 220 mW/cm2 at 600 °C when humidified (3 vol.% H2O) hydrogen as fuel and oxygen as oxidant.
      PubDate: 2015-03-01
       
  • Synthesis and electrochemical properties of Li-rich cathode material Li[Ni
           x Li (1/3−2x/3) Mn (2/3−x/3) ]O 2 ( x  = 1/4, 1/3)
           for Li-ion battery
    • Abstract: Abstract Cathode materials Li[Ni x Li(1/3−2x/3)Mn(2/3−x/3)]O2 with different content of Ni (x = 1/4, 1/3) were synthesized using co-precipitation reaction. Power X-ray diffraction measurement confirmed that the obtained Li[Ni x Li(1/3−2x/3)Mn(2/3−x/3)]O2 (x = 1/4, 1/3) possessed a layered structure and \( R\overline{3} m \) space group. Scanning electron microscopy results showed that all Li[Ni x Li(1/3−2x/3)Mn(2/3−x/3)]O2 were characterized by a large amount of micro-nanoparticles with tuck form. Based on our previous studies of conventional layered materials, powerful electrochemical evidences of charge/discharge mechanisms and electrode/electrolyte interfaces properties were given by differential capacitance curves and electrochemical impedance spectroscopy (EIS). It was found that the first charge differential capacitance curves of the Li-rich materials displayed three major reactions: the oxidation of Ni2+/4+, the extraction of oxygen and the exchange of proton, and the capacity contribution are 65.2, 25.6, and 9.2 % respectively. Nevertheless, the oxidation of Ni2+/4+ was the only reaction in the following charge processes. The EIS results showed that Li-rich material could form a stable SEI film in the charge/discharge process even though the breakdown or dissolution of the resistive SEI film appearing in the high voltage; the electronic properties changed with oxidation reactions and phase transition; and the continuous increase of the charge transfer resistance, which might be the major reason of the poor high-rate performance of Li-rich materials.
      PubDate: 2015-03-01
       
  • Surfactant-mediated synthesis of ZnCo 2 O 4 powders as a high-performance
           anode material for Li-ion batteries
    • Abstract: Abstract The synthesis as well as the electrochemical properties study of highly crystalline ZnCo2O4 powders is presented. ZnCo2O4 powders with a particle diameter of 15–35 nm have been successfully prepared with the surfactant-mediated method. The thorough structural characterization including X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to examine the morphology and the microstructure of the final product. The as-synthesized powders were used as anode materials for lithium-ion battery, whose charge–discharge properties, cyclic voltammetry, and cycle performance were examined and revealed very good properties. Galvanostatic cycling of ZnCo2O4 powders in the voltage range 0.005–3.0 V versus Li at 60 mA g−1 maintained charge and discharge capacities of 1,308 and 1,336 mAh g−1 after 40 cycles when cycled at 25 °C, respectively.
      PubDate: 2015-03-01
       
  • Different behaviors of PdAu/C catalysts in electrooxidation of
           propane-1,3-diol and propane-1,2-diol
    • Abstract: Abstract The different behaviors of PdAu/C catalysts in the electrocatalytic oxidation of propane-1,3-diol and propane-1,2-diol in alkaline solution are investigated. The PdAu/C catalysts are prepared by means of the chemical co-deposition of Pd and Au on carbon black and characterized by instrumental analysis and electrochemical analysis. In propane-1,3-diol oxidation on the PdAu/C catalysts, the oxidation potential is similar to that on the Pd/C catalyst rather than that on the Au/C catalyst, but the peak current density is higher than that on Pd/C and Au/C catalysts. Furthermore, the peak current density increases with increasing Au content. The PdAu/C catalysts also show enhanced resistance to the poisoning. However, the improvement in the activity of Pd by the addition of Au and the difference in the activity of the PdAu/C catalysts with different Pd/Au compositions in propane-1,2-diol oxidation are not as obvious as that in propane-1,3-diol oxidation.
      PubDate: 2015-03-01
       
  • Iridium oxide-based chemical sensor for in situ pH measurement of
           oilfield-produced water under subsurface conditions
    • Abstract: Abstract The objective of this study was to develop a pH sensor for monitoring hydrogen ion activity in situ in oilfield-produced water under subsurface conditions. An iridium oxide film was prepared, and the performance of the iridium oxide film was evaluated in produced water using a series of high salinities, temperatures, and pressures. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were employed to assess the morphology and oxidation state of the iridium oxide film. A series of open-circuit potential (OCP) measurements were performed to access the sensitivity and stability of the iridium oxide film electrode in produced water. Research results indicated that the pH sensor exhibits a very high sensitivity in the environment with varied interference ions, including Na+, Mg2+, Ca2+, Cl−, and SO4 2−, and the existence of sodium chloride in produced water made a slight positive shift of potential. The iridium oxide film-based pH sensor exhibited a near-Nernstian response at −57.9 mV/pH in produced water. An increase in temperature from 24 to 80 °C decreased the pH potential. Compared with the theoretical Nernst equation, the iridium oxide sensor showed fair Nernstian behavior at high temperatures. The iridium oxide pH sensor was accurately investigated under high pressure; the sensor seems independent of pressure, and the slope is the same at different potentials under a wide range of pressures.
      PubDate: 2015-03-01
       
  • Ionic transport in glycerol-water mixtures
    • Abstract: Abstract Glycerol-water mixtures have been extensively studied in the past several years. One of the most used techniques to study such mixtures is dielectric spectroscopy. Here, we use it to explore the range of low frequencies. This for two main reasons: (i) although electrode polarization, occurring at frequencies below 1 kHz, is normally considered as a geometrical non-desirable effect, a detailed study of how it behaves with temperature and concentration has not been pursued, and (ii) this is the interval where the transport of ions takes place in biological cells. We found that even when the viscosity of the glycerol-water mixture is large, charge transport occurs. Our aim is to relate such results with the transport of ions in organisms that come out from hibernation.
      PubDate: 2015-03-01
       
  • Polymer gel combustion synthesis of LiFePO 4 /C composite as cathode
           material for Li-ion battery
    • Abstract: Abstract LiFePO4/C has been synthesized by polymer gel combustion method. Of aniline monomer, 0.5 and 1.0 ml were used for the different amount of gel formation. The particle sizes of LiFePO4/C composites designated as lithium iron phosphate (0.5) (LFP(0.5)) and LFP(1.0) were estimated as ∼400 and ∼100 nm for the powders synthesized with 0.5 and 1.0 ml of monomers, respectively. The final particle size of the LiFePO4/C depends on the initial monomer content used in the synthesis process. Thicknesses of carbon coating on the particles of LFP(0.5) and LFP(1.0) powders, as revealed by TEM observation, are ∼3 and ∼7 nm, respectively. The sample LFP(1.0) delivers discharge capacities of 72 and 60 mAh g−1 which are higher than those of LFP(0.5) at fast discharging rates of 5 and 10 C. The higher rate capability of sample LFP(1.0) was due to small particle size, low charge transfer resistance, and higher Li+ diffusion coefficient as compared to LFP(0.5).
      PubDate: 2015-03-01
       
  • Mechanically exfoliated ultra-thin WO 3 nanostructures: study of their
           enhanced electrical properties
    • Abstract: Abstract Ultra-thin orthorhombic β-WO3 nanoflakes were prepared by two-step sol-gel-exfoliation method and sintered at 550 and 650 °C, respectively. Their morphology and electrical properties were investigated by the following material characterisation techniques: energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), current sensing force spectroscopy atomic force microscopy (CSFS-AFM, or PeakForce TUNA™), Fourier transform infra-red absorption spectroscopy (FTIR), linear sweep voltammetry (LSV) and Raman spectroscopy. CSFS-AFM analysis exhibited good correlation between the topography of the developed nanostructures and various features of WO3 nanoflakes. It was found that β-WO3 nanoflakes annealed at 550 °C possess distinguished and exceptional thickness-dependent properties in comparison with the bulk, microstructured and nanostructured WO3 synthesized at alternative temperatures.
      PubDate: 2015-03-01
       
  • Fabrication of LiMnPO 4 -MWCNT cathode material via vapor phase hydrolysis
           and its electrochemical properties
    • Abstract: Abstract Olivine-structured LiMnPO4-MWCNT cathode materials are fabricated via vapor phase hydrolysis without calcination process and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption-desorption isotherm analysis, galvanostatic charging-discharging test, and electrochemical impedance spectroscopy (EIS). All XRD results show LiMnPO4 and multi-walled carbon nanotubes (MWCNTs) coexisted in the obtained sample. The appropriate temperature to synthesize LiMnPO4 cathode material is 200 °C, and MWCNT addition accelerates growing of (020) plane. SEM shows MWCNTs have been coated onto the surface of LiMnPO4 and the morphology of LiMnPO4 can be tuned from fragment to long strip by varying MWCNT contents. EIS results indicate that MWCNTs are able to accelerate the diffusion of Li+ ion across LiMnPO4-MnPO4 boundary, so galvanostatic charging-discharging test indicates that the initial capacity of LiMnPO4-MWCNT composites is higher than that of LiMnPO4. The best initial discharge capacity is 113 mAh/g (0.1 C) when MWCNT addition is 5 % due to the synthetic effect of improved electrochemical performance and relatively small dimensions.
      PubDate: 2015-03-01
       
  • Ionic mobility of (0.9)[0.75AgI:0.25AgCl]:0.1SiO 2 in space charge
           depolarization
    • Abstract: Abstract The analysis of ionic mobility of Ag+ ions in the nano-composite material is performed. The material is space charge polarized initially by applying a dc field ~0.5 V. The depolarization potential is recorded at various isothermal conditions in the temperature range of 300–535 K. By considering open circuit condition, drift and trapped ionic mobility are analyzed and the results are compared with the ionic mobility measured by conventional transient ionic current (TIC) and experimental techniques in the same temperature range.
      PubDate: 2015-03-01
       
  • Magnetite/carbon nanotubes nanocomposite: facile hydrothermal synthesis
           and enhanced cycling performance and high-rate capability as anode
           material for lithium-ion batteries
    • Abstract: Abstract In this work, we report a general and feasible approach for the fabrication of Fe3O4/carbon nanotubes (CNTs) nanocomposite through a hydrothermal method followed by an in situ thermal reduction, without any reducing agents. The nanocomposite was characterized by x-ray power diffraction (XRD) and scanning electron microscopy (SEM). The results revealed that the CNTs in the prepared Fe3O4/CNTs nanocomposite intertwines with Fe3O4 nanoparticles to form a three-dimensional (3D) network wiring, and almost all the Fe3O4 nanoparticles with diameters ranging from 50 to 100 nm. The electrochemical performance of the Fe3O4/CNTs nanocomposite displayed an initial discharge capacity of 1,421 mAh g−1 and maintained 1,030 mAh g−1 up to 55 cycles at 0.1 C (1 C = 924 mAh g−1). When the current density is 0.5, 1, 2, 5, and 1 C, the Fe3O4/CNTs nanocomposite still exhibited discharge capacity of 1,049, 995, 802, 433, and (950 ± 50) mAh g−1, respectively. Compared to commercial Fe3O4, the Fe3O4/CNTs nanocomposite showed enhanced cycling performance and high-rate capability due to the synergetic effects, highlighting the importance of maximum use of the Fe3O4 and CNTs for energy storage applications in high-performance lithium-ion batteries (LIBs).
      PubDate: 2015-03-01
       
  • Effect of oxygen activity on chromium segregation in Cr-doped TiO 2 single
           crystal
    • Abstract: Abstract The present work determined the effect of chromium segregation on surface and near-surface composition of Cr-doped TiO2 (0.05 at.% Cr) after annealing in oxidising and strongly reducing environments at 1,073 and 1,273 K. The segregation-induced depth profiles were determined by secondary ion mass spectrometry (SIMS). It was observed that annealing in oxidising conditions [p(O2) = 105 Pa] and reducing conditions [10−11 Pa > p(O2) > 10−15 Pa] results in an enrichment and depletion of the surface layer in chromium, respectively. The observed effects may be used for tailoring the surface and near-surface composition in order to impose desired properties.
      PubDate: 2015-03-01
       
  • Directly carbonized lotus seedpod shells as high-stable electrode material
           for supercapacitors
    • Abstract: Abstract In this work, we demonstrate a simple and effective activation-free carbonization method to prepare porous carbon from lotus seedpod shell―a kind of natural biomass. It reveals that the carbonization temperature plays a crucial role in the determination of surface areas and capacitive performances of as-obtained porous carbon samples. The pore size and specific surface area of the samples were measured to be in the ranges of 2.0–2.2 nm and 261.7–563.4 m2 g−1, respectively. The carbon sample obtained at a carbonization temperature of 600 °C (carbon-600) exhibits the maximum Barrett–Emmett–Teller (BET) surface area of 563.4 m2 g−1 and the highest specific capacitance of 165 F g−1 at a current density of 0.5 A g−1. More importantly, the carbon-600 sample reveals unexceptionable capacitance retention of 95.3 % after 10,000 charge–discharge cycles, clearly indicating its excellent cycling stability. This work gives a simple and efficient approach for producing cost-effective porous carbons with high performance for supercapacitors.
      PubDate: 2015-03-01
       
  • Electrochemical properties of a poly(ethylene carbonate)-LiTFSI
           electrolyte containing a pyrrolidinium-based ionic liquid
    • Abstract: Abstract A novel polymer electrolyte membrane comprising poly(ethylene carbonate) (PEC), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt, and N-n-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) ionic liquid is prepared by a solvent-free procedure, combining annealing and hot-pressing. The electrochemical properties of the electrolyte are investigated in terms of ionic conductivity, Li transference number (t Li+), and electrochemical stability by a combined study involving electrochemical impedance spectroscopy (EIS), chronoamperometry, and voltammetry. The thermal characteristics are assessed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results reveal an ionic conductivity of a PEC-Pyr14TFSI-LiTFSI electrolyte of the order of 10−5 S cm−1 at 80 °C and t Li+ as high as 0.66 with the intrinsic amorphous nature of the PEC matrix. Furthermore, a Li polymer cell coupling LiFePO4 cathode and the electrolyte is assembled and galvanostatically cycled. The result of this charge-discharge test demonstrates a 3.5-V battery which can be used at 80 °C and a current rate of C/20, delivering a reversible capacity of the order of 150 mAh g−1.
      PubDate: 2015-03-01
       
  • Electrospun preparation and lithium storage properties of NiFe 2 O 4
           nanofibers
    • Abstract: Abstract In this paper, we successfully synthesized NiFe2O4 nanofibers via simple electrospinning process followed by calcination process. Only peaks of NiFe2O4 could be observed from X-ray diffractometry patterns, indicating the formation of pure compound. Scanning electron microscope and transmission electron microscopy images showed the as-spun NiFe2O4 nanofibers calcined at 800 °C ranged from 130 to 220 nm in diameter. The electrochemical properties of the nanofibers anode material for lithium-ion batteries were tested. It was found that the obtained NiFe2O4 nanofibers calcined at 800 °C possessed higher reversible capacity and cycling stability than that of the samples calcined at 600 °C. The as-prepared NiFe2O4 nanofibers calcined at 800 °C exhibited a high initial discharge capacity of 1,304 mAh g−1 in the potential range of 3.0–0.01 V, and the stabilized capacity was as high as 514 mAh g−1 after 60 cycles. Moreover, the as-prepared NiFe2O4 nanofibers calcined at 800 °C also exhibited high capacity at higher charge/discharge rate.
      PubDate: 2015-03-01
       
 
 
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