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  Subjects -> ENGINEERING (Total: 2156 journals)
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    - ENGINEERING (1164 journals)
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ENGINEERING (1164 journals)            First | 2 3 4 5 6 7 8 9 | Last

International Journal of Hypersonics     Full-text available via subscription   (Followers: 3)
International Journal of Imaging Systems and Technology     Hybrid Journal   (Followers: 2)
International Journal of Impact Engineering     Hybrid Journal   (Followers: 8)
International Journal of Information Acquisition     Hybrid Journal   (Followers: 1)
International Journal of Innovation and Applied Studies     Open Access   (Followers: 3)
International Journal of Innovation Science     Full-text available via subscription   (Followers: 6)
International Journal of Innovative Technology and Research     Open Access  
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: 8)
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: 11)
International Journal of Network Management     Hybrid Journal  
International Journal of Nonlinear Sciences and Numerical Simulation     Hybrid Journal  
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: 10)
International Journal of Pattern Recognition and Artificial Intelligence     Hybrid Journal   (Followers: 6)
International Journal of Pavement Engineering     Hybrid Journal   (Followers: 3)
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   (Followers: 1)
International Journal of Polymer Analysis and Characterization     Hybrid Journal   (Followers: 5)
International Journal of Polymer Science     Open Access   (Followers: 20)
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: 3)
International Journal of Reliability, Quality and Safety Engineering     Hybrid Journal   (Followers: 7)
International Journal of Renewable Energy Technology     Hybrid Journal   (Followers: 9)
International Journal of Robust and Nonlinear Control     Hybrid Journal   (Followers: 3)
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: 2)
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 Superconductivity     Open Access  
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: 8)
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   (Followers: 1)
International Journal of Technology Management and Sustainable Development     Hybrid Journal   (Followers: 1)
International Journal of Technology Policy and Law     Hybrid Journal   (Followers: 5)
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     Hybrid Journal  
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: 8)
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: 3)
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  
International Scholarly Research Notices     Open Access   (Followers: 225)
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  
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 2)
Irrigation and Drainage Systems     Hybrid Journal   (Followers: 1)
ISA Transactions     Full-text available via subscription   (Followers: 1)
IT Professional     Full-text available via subscription   (Followers: 3)
Johnson Matthey Technology Review     Open Access   (Followers: 2)

  First | 2 3 4 5 6 7 8 9 | Last

Journal Cover   Ionics
  [SJR: 0.497]   [H-I: 27]   Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1862-0760 - ISSN (Online) 0947-7047
   Published by Springer-Verlag Homepage  [2299 journals]
  • Enhanced high-temperature cycling stability of LiNi 1/3 Co 1/3 Mn 1/3 O 2
           -coated LiMn 2 O 4 as cathode material for lithium ion batteries
    • Abstract: Abstract To enhance the electrochemical performances of LiMn2O4 at elevated temperature, we proposed a sol–gel method to synthesize LiNi1/3Co1/3Mn1/3O2-modified LiMn2O4. The physical and electrochemical performances of pristine and LiNi1/3Co1/3Mn1/3O4-coated LiMn2O4 cathode materials were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical measurements, respectively. The results indicated that about 5–6-nm-thick layer of LiNi1/3Co1/3Mn1/3O2 formed on the surface of the LiMn2O4 powders. The modified LiMn2O4 exhibited excellent storage performance at 45, 55, and 65 °C compared to the pristine one, which was attributed to the suppression of electrolyte decomposition and the reduction of Mn dissolution.
      PubDate: 2015-07-01
       
  • Influence of Fe substitution on cycling stability of Li[Li 0.2 Ni 0.13 Mn
           0.54 Co 0.13 ]O 2 cathode for lithium ion batteries
    • Abstract: Abstract With an aim to broaden the understanding of factors influencing oxygen loss, reversible capacity, and cyclic stability of lithium-rich layered oxide cathodes for lithium ion batteries, a series of Fe substituted Li[Li0.2Ni0.13Mn0.54Co0.13]O2 samples, Li[Li0.2Ni0.13-x/2Mn0.54-x/2Co0.13Fe x ]O2 (x = 0, 0.02, 0.04, and 0.08) and Li[Li0.2Ni0.13Mn0.54Co0.13-y Fe y ]O2 (y = 0, 0.02, 0.04, and 0.06), have been synthesized with a hydroxide co-precipitation method and comparatively studied with X-ray diffraction (XRD), scanning electron microscope (SEM), and charging/discharging measurements. The results indicate that with increasing the Fe substitution for either Co3+ or [Ni0.5Mn0.5]3+, the oxygen loss during the first charge dramatically decreases, leading to the decrease in reversible capacity. Interestingly, the substitution for Co3+ can significantly suppress the voltage decay of the material with extended cycling. For instance, the decayed voltage in 30 cycles is 0.21 V for Li[Li0.2Ni0.13Mn0.54Co0.13]O2, while only 0.11 V for Li[Li0.2Ni0.13Mn0.54Co0.07Fe0.06]O2. The suppression mechanism is discussed.
      PubDate: 2015-07-01
       
  • Novel sodium bismuth sulfide nanostructures: a promising anode materials
           for sodium-ion batteries with high capacity
    • Abstract: Abstract A simple and versatile method for preparation of hierarchical sodium bismuth sulfide (NaBiS2) nanostructures is developed via a simple solvothermal route. They were firstly tested as anode materials for sodium-ion battery. NaBiS2 is found to be characteristic of high capacity and low potential versus Na/Na+, which would be a promising anode material for sodium-ion battery. The NaBiS2 nanoparticles electrode delivers a second discharge capacity of 692.4 mA h g−1 at a current density of 10 mA g−1. A possible electrochemical reaction mechanism was proposed.
      PubDate: 2015-07-01
       
  • Preparation and performance of a composite polyimide/poly(vinylidene
           fluoride- co -hexafluoropropylene)/nano-Al 2 O 3 polymer electrolyte for
           lithium-sulfur cell
    • Abstract: Abstract A novel gel polymer electrolyte (GPE) based on an electrospun polymer membrane of polyimide (PI) activating with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and further coating with nano-Al2O3 was prepared, and its performance for lithium-sulfur (Li-S) cell was investigated. It is found that the Li-S cell using the new GPE enabled achieving a stable discharge capacity of 820 mAh g−1 after more than 100 cycles. This new GPE system with activating with PVDF-HFP and further coating with nano-Al2O3 was capable of upholding the electrolyte solution and can suppress the dissolution of the intermediate products generated during the discharge process and thus improves the performance of Li-S cell.
      PubDate: 2015-07-01
       
  • Thermal and Electrical properties of Ce 0.8−x Gd x Sm 0.2 O
           2−δ materials for SOFC applications
    • Abstract: Abstract Gadolinium and samarium co-doped ceria electrolyte materials Ce0.8−x Gd x Sm0.2O2−δ (x = 0, 0.02, 0.04, 0.06) were prepared by using sol–gel method. The prepared materials were characterized by X-ray diffraction and scanning electron microscopy. The phase identification and the cell parameters were determined by X-ray powder diffraction. Thermal expansion of prepared materials was measured using dilatometric method in the temperature range 30–1000 °C. The thermal expansion increases linearly increasing temperature. The electrical conductivity was measured using impedance spectroscopy. Among the prepared compositions, Ce0.74Gd0.06Sm0.2O2−δ showed higher electrical conductivity and lower activation energy at 450 °C. Which makes suitable as an electrolyte and it may be a promising candidate for as an electrolyte in IT-SOFCs.
      PubDate: 2015-07-01
       
  • Effects of MoO 3 on secondary alkaline zinc anode
    • Abstract: Abstract MoO3 was added to the zinc electrode of Zn/KOH/NiOOH cells. The combination of anodic polarization curve, constant current charge–discharge, and impedance spectra was used to investigate the effects of adding MoO3 on the electrochemical performance of zinc anode. The cell with MoO3 added in zinc anode reached 360 cycles before its capacity fell below 90 % of the initial capacity, while the cell without MoO3 failed after 180 cycles. Based on the scanning electron microscopy observation, the significant improvement of cycle stability can be attributed to the addition of MoO3, which helps zinc electrode to stay in a loose and porous structure, such texture is definitely in favor of the diffusion of OH− ions, facilitating the utilization of active material. But for standard electrode without MoO3, zinc anode is easy to passivate owing to the formation of dense ZnO film on zinc electrode surface. This compact film restricts OH− ion diffusion and decreases active area of zinc electrode. Therefore, MoO3-added electrode can effectively improve the cycle performance of the Ni–Zn battery.
      PubDate: 2015-07-01
       
  • Optimization of ionic conductivity of electrospun polyacrylonitrile/poly
           (vinylidene fluoride) (PAN/PVdF) electrolyte using the response surface
           method (RSM)
    • Abstract: Abstract Polyacrylonitrile/poly (vinylidene fluoride) fibrous membranes were prepared by electrospinning of PAN and PVdF solution and were soaked in 1 M lithium perchlorate (LiClO4) in ethylene carbonate (EC)/diethyle carbonate (DEC) (1:1 wt.%) solution in order to prepare polymer electrolyte membranes. Response surface method (RSM) was used to obtain a quantitative relationship between selected electrospinning parameters, i.e., applied voltage, solution concentration, and PVdF content. The measured response is ionic conductivity of electrolyte membranes. The Box–Behnken method was applied to design of experiments. Importance of parameters in the model was determined by analysis of variance (ANOVA). The model was used to find the maximum ionic conductivity of electrolyte membranes as optimum result. The morphology of fibers was investigated by field emission scanning electron microscopy (FESEM). FESEM results show that the PAN/PVdF membrane has interconnected multifibrous layers with ultrafine porous structure that leads to a high ionic conductivity and efficient lithium ion transport. Produced fibrious membranes show uniform morphology. Average fiber diameter lies between 116 and 379 nm, and membranes have high porosity of 48–90 % and electrolyte uptake of 303–493 %. The polymer electrolyte membranes show good ionic conductivity in the order of 10−3 S cm−1 at ambient temperature. Ionic conductivity decreases with increase of solution concentration and increases with increase of PVdF composition. Voltage has no significant effect on ionic conductivity of the membranes. The model predicted the maximum ionic conductivity of 7.98 mS cm−1 when the voltage was set at 21.57 kV, the solution concentration set at 14.02 wt.%, and the PVdF composition set at 69.48 wt.%.
      PubDate: 2015-07-01
       
  • Electrical properties and defect chemistry of indium-doped TiO 2 .
           Thermoelectric power
    • Abstract: Abstract This work studied the effect of indium on the semiconducting properties of TiO2 (rutile) at elevated temperatures (1023–1273 K) in the gas phase of controlled oxygen activity in the range of 10−16 Pa < p(O2) < 105 Pa. The studies were performed using the measurements of thermoelectric power of In-doped TiO2 (0.4 at.% In) as a function of oxygen activity and temperature. The obtained data indicates that indium is incorporated into the TiO2 lattice according to the dual mechanism leading to the formation of donors and acceptors in the interface (surface and grain boundary) layer and the bulk phase, respectively. This effect is considered in terms of a quasi-isolated surface layer that differs from the bulk phase in terms of semiconducting properties and the related defect disorder.
      PubDate: 2015-07-01
       
  • Preparation and electrochemical performance of spinel LiNi 0.5−x Mn
           1.5+x O 4 ( x  = 0, 0.05, 0.1) hollow microspheres as cathode
           materials for lithium-ion batteries
    • Abstract: Abstract The spinel LiNi0.5−x Mn1.5+x O4 (x = 0, 0.05, 0.1) including LiNi0.5Mn1.5O4, LiNi0.45Mn1.55O4, and LiNi0.4Mn1.6O4 hollow microspheres has been prepared by adjusting the stoichiometric ratios of Ni and Mn with an impregnation method followed by a simple solid-state reaction. They are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, high-resolution transmission electron microscope, X-ray photoelectron spectroscopy, and electrochemical tests. The results show that LiNi0.5Mn1.5O4 is the ordered with the space group of P4332, but LiNi0.45Mn1.55O4 and LiNi0.4Mn1.6O4 are the disordered with the space group of Fd3m. All the three types of hollow microspheres have the similar primary particles. Compared to LiNi0.5Mn1.5O4, partial Ni atoms are substituted by Mn atoms in LiNi0.45Mn1.55O4 and LiNi0.4Mn1.6O4 lattices along with incorporation of small amounts of Mn3+. Although the ordered LiNi0.5Mn1.5O4 hollow microspheres deliver the highest capacity of 128.5 mAh/g at 1 C among the three types of spinel materials, the disordered LiNi0.45Mn1.55O4 hollow microspheres exhibit the highest capacity of 96.8 mAh/g at 10 C. The superior rate capability of LiNi0.45Mn1.55O4 hollow microspheres is attributed to the combination of the increased electronic conductivity and Li+-ion diffusion by moderate Mn3+ incorporation, along with the hierarchical structure.
      PubDate: 2015-07-01
       
  • Insight of conduction mechanism of Gd 3+ -containing lithium borate
           glasses
    • Abstract: Abstract The main aim of the present work is to study the conducting properties of lithium borate glasses with Gd3+ ions. The Gd2O3-containing lithium borate glass system was prepared by conventional quenching method. The impedance data of prepared glasses were analysed to get insight of conductivity and conduction process. The conductivity of present glass system is governed by mobile Li+ ions. Scaling shows that the conduction phenomenon is compositionally dependent.
      PubDate: 2015-07-01
       
  • Enhancement of the electrochemical performance of LiFePO 4 /carbon
           nanotubes composite electrode for Li-ion batteries
    • Abstract: Abstract LiFePO4 is very good potential cathode materials for the power lithium-ion batteries because of its high theoretical capacity and high voltage, but its electrochemical performance suffers from the low electronic conductivity. In this paper, the multi-walled carbon nanotubes (MWCNTs)/LiFePO4 composites cathode materials are prepared by ball milling. With high conductivity and the network structure existing in the LiFePO4 electrode, carbon nanotubes can reduce internal resistance and increase practical capacity and cycle stability of LiFePO4. As electrodes of lithium battery, the charge–discharge capacity, cyclic voltammetry, cycle life, alternating current impedance, and discharge temperatures characteristic of LiFePO4/MWCNTs (the loading of MWCNTs from 0 to 20 %) are investigated. The resistances of LiFePO4/MWCNTs decrease with the increase of MWCNTs loading and reach a minimal value of 56 Ω in the 10 % loading of MWCNTs, and result in the improvement of electrochemical performance. It is found that the composite electrode with 10 % loading of MWCNTs exhibits a best charge–discharge performance, and has initial charge capacities of 148 mAhg−1 and discharge capacities of 145 mAhg−1, respectively at 0.1 °C rate and the capacity retention is 98 %. The result of the pure LiFePO4 shows that the discharge capacity is 131 mAhg−1 at the rate of 0.5 °C, which means the increase in capacity of the LiFePO4/MWCNTs electrode achieves 16 %. The LiFePO4/MWCNTs composites also have perfectly high temperature performance due to the excellent thermal stability of the MWCNTs, and the discharge capacity of the composite electrode is 164 mAhg−1 at 0.1 °C rate in the temperature of 60 °C. After 30 cycles, the capacity still maintains as 163 mAhg−1 and the capacity retention is 99 %. The excellent cycle performance of the LiFePO4/MWCNTs electrode may attribute to the netlike-structure mechanical and electrical performance of MWCNTs.
      PubDate: 2015-07-01
       
  • Electric double-layer capacitors with corn starch-based biopolymer
           electrolytes incorporating silica as filler
    • Abstract: Abstract Solid-state electric double-layer capacitors (EDLCs) based on corn starch biodegradable polymer electrolytes are fabricated. Silica is added into the corn starch polymer electrolytes to improve the ionic conductivity and capacitance of the EDLCs. The ionic conductivity as a function of temperature obeys the Arrhenius equation indicating ionic hopping mechanism in the polymer electrolytes. Linear sweep voltammetry shows that the prepared corn starch-based biopolymer electrolyte is stable in the range from −2.5 to 2.5 V. Electrical capacitance performances of these capacitors are studied by cyclic voltammetry, galvanostatic charge–discharge, and AC impedance spectroscopy. The discharge characteristics have been found to be almost linear, which confirms the capacitive behavior of the EDLC cell. The fabricated EDLC cells perform good cyclability up to 500 cycles with more than 90 % of coulombic efficiency.
      PubDate: 2015-07-01
       
  • Studies of electric, dielectric, and conduction mechanism by OLPT model of
           Li 4 P 2 O 7
    • Abstract: Abstract The polycrystalline samples of Li4P2O7 were prepared by solid-state reaction technique. The formation of the compounds was checked by X-ray diffraction technique (XRD). Detailed dielectric and electrical properties of the compounds were analyzed as a function of frequency (200 Hz–5 MHz) and temperature (611–671 K). The impedance data were well fitted to two equivalent electrical circuits. The results of the modulus study reveal the presence of two distinct relaxation processes suggesting the presence of grains and grain boundaries in the sample. Analysis of the dielectric constants ε″ and loss tangent tan (δ) with frequency shows a distribution of relaxation times. The activation energy found from the Arrhenius plot confirms that the conduction process in the material is not due to simple hopping mechanism. The temperature dependence of frequency exponent s was investigated to understand the conduction mechanism in Li4P2O7. The overlapping large polaron tunneling (OLPT) model can explain the temperature dependence of the frequency exponent.
      PubDate: 2015-07-01
       
  • High-efficiency PdCu alloy nanocube catalyst supported on N-doped
           multiwalled carbon nanotubes for alcohol electrooxidation
    • Abstract: Abstract N-doped of the support is generally important to immobilize metal nanoparticles on the support, produce some active Me–N sites, and generate good electrocatalytic activity and stability. A facile and low-cost preparation of N-doped multiwalled carbon nanotube (N-MWCNTs)-supported hollow PdCu alloyed nanocube catalyst (H–PdCu/N-MWCNTs) was introduced in this paper. To increase the stability and utilization ratio of the noble metal, a two-step strategy was employed, which included the synthesis of N-MWCNTs using polypyrrole (ppy) as the source of nitrogen and the preparation of the hollow PdCu alloyed nanocubes. According to transmission electron microscopy (TEM) measurements, the as-prepared hollow PdCu alloyed nanocube catalyst has superior dispersibility, and the average diameter is about 50 nm. X-ray photoelectron spectroscopy (XPS) measurements reveal that N atoms have been doped in multiwalled carbon nanotubes (MWCNTs) and there is abundance of pyridinic N and graphitic N species on N-MWCNT surface. The electrochemical measurements indicate that the hollow PdCu alloyed nanocube catalyst has a better electrocatalytic activity and stability for the alcohol oxidation. It is concluded that the H–PdCu/N-MWCNTs would be a potential candidate as an anode electrocatalyst in direct alcohol fuel cell.
      PubDate: 2015-07-01
       
  • A facile electrochemical synthesis of three-dimensional porous Sn-Cu
           alloy/carbon nanotube nanocomposite as anode of high-power lithium-ion
           battery
    • Abstract: Abstract 3D (three-dimensional) porous Sn-Cu alloy/carbon nanotube (CNT) nanocomposite is successfully produced by electrodeposition using a 3D porous Cu prepared by electroless plating as the substrate. Scanning electron microscope (SEM) results demonstrate that there are a large amount of interconnected pores with the diameter of about 3 μm in the nanocomposite, and the pore walls are composed of Sn-Cu alloy nanoparticles uniformly encapsulated on CNT networks. Owing to the 3D porous structure that can accommodate the volumetric variation and alleviate the stress caused from the large volumetric changes during charging/discharging, CNT networks can enhance the electrode strength and prevent active materials from exfoliation during charging/discharging through steel-reinforced concrete mechanism; this nanocomposite delivers excellent cyclability and large high-rate capacity. The first specific reversible capacity at the current density of 100 mA g−1 is 546.6 mAh g−1 and remains 370.1 mA g−1 after 100 cycles. The reversible specific capacity at 1600 mA g−1 remains 35.3 % of that at 200 mA g−1.
      PubDate: 2015-07-01
       
  • Synthesis, characterization and analytical application of cellulose
           acetate-tin (IV) molybdate nanocomposite ion exchanger: binary separation
           of heavy metal ions and antimicrobial activity
    • Abstract: Abstract A novel cellulose acetate-tin (VI) molybdate nanocomposite (CA/TMNC) exchanger was synthesized by sol-gel method and characterized using techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and thermal analysis. Transmission electron microscopy (TEM) results indicated the formation of particles of nanodimensions. The ion exchange capacity, pH titration, elution behavior, and distribution coefficient were also investigated. CA/TMNC showed enhanced ion exchange capacity as compared to its inorganic counterpart. The distribution coefficient (K d ) values for different toxic heavy metal ion such as Pb+2, Cd+2, Mg+2, Zn+2, Co+2, Cu+2, Mn+2, Cr+3, Ni+2, and Fe+2 has been studied in double-distilled water by batch process. On the basis of K d values, four binary separation of the metal ions have been achieved on the column of CA/TMNC. The material is found to be selective for Pb2+ and Cd2+ ions; about more than 94 % of Pb2+ and 93 % of Cd2+ ions were recovered in each separation. The antibacterial activity of CA/TMNC was explored against Escherichia coli. The results confirmed the bacteriostatic nature of the CA/TMNC.
      PubDate: 2015-07-01
       
  • Surface modification of Mg-doped spinel with different Li-containing
           manganese oxides
    • Abstract: Abstract Mg-doped spinel LiMg0.05Mn1.95O4 was synthesized and coated with three types of Li-containing manganese oxides (Li2Mn4O9, Li4Mn5O12, and LiNi0.5Mn1.5O4) to improve the cycling properties at room temperature and at 50 °C via a coprecipitation method. The as-prepared spinels were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), inductively coupled plasma (ICP), and electrochemical tests. The results indicate that all the coated samples show enhanced electrochemical performance including higher initial charge-discharge capacities and more stable cycling properties as well as improved coulombic efficiency. Especially, the LiNi0.5Mn1.5O4-coated sample delivers the highest initial discharge capacity of 129 mAh/g with capacity retention of 82.5 % as well as the best coulombic efficiency of 92.1 %. This improved performance could be attributed to the enhanced electrochemical kinetics by successful surface modification of spinels with Li-containing manganese oxides via coprecipitation method.
      PubDate: 2015-07-01
       
  • Effect of cooling on the structure and electrochemical properties of 0.3Li
           2 MnO 3 · 0.7LiNi 0.5 Mn 0.5 O 2 cathode material
    • Abstract: Abstract The cooling rate after annealing treatment was proved to be important for the structure and electrochemical performances of the layered oxide 0.3Li2MnO3 · 0.7LiNi0.5Mn0.5O2 material, which has been synthesized using a sol–gel method. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), nondestructive nano-computed tomography (nano-CT), and Brunauer-Emmett-Teller (BET) surface area measurement were used to characterize the structure and micromorphology of the material. It was demonstrated that the material quenched by liquid nitrogen (AN-material) showed less defects in structure and larger specific surface area than the material cooled naturally (AF-material). Electrochemical measurement showed that the AN-material exhibited better electrochemical performance as cathode candidate for lithium-ion batteries. The initial discharge capacity and coulombic efficiency reached 277.4 mAh g−1 and 84.1 % for AN-material, while 257.1 mAh g−1 and 78.4 % for AF-material. In addition, the AN-material also exhibited lower charge transfer resistance than AF-material.
      PubDate: 2015-07-01
       
  • Calcium terephthalate/graphite composites as anode materials for
           lithium-ion batteries
    • Abstract: Abstract We have reported a conjugated carbonyl organic calcium terephthalate (CaTPA)-based organic/inorganic composite as anode material for lithium-ion batteries. The bulk CaTPA presents a low electronic conductivity leading to a large electrochemical polarization during charge/discharge process. Graphite is chosen as a conductive additive to improve its electrochemical performance via ball milling. The effect of graphite amount on the electrochemical properties of CaTPA is investigated. The composite with the weight ratio of 100:10 (CaTPA/graphite) (named CaTPAG10) shows the smallest electrochemical polarization, largest Li+ diffusion coefficient, and best rate capability, delivering discharge capacity of 233 mAhg−1 at current rate of 0.1 C and discharge voltage plateau at ~0.8 V. CaTPAG10 further exhibits good cycling performance, from 169 mAhg−1 down to 161 mAhg−1 after 50 cycles, giving a capacity retention of 95 % at 2 C compared with that of 89 % for the pristine CaTPA. To explore commercial application of CaTPA, a full cell with LiCoO2 and CaTPAG10 as a cathode and an anode material, respectively, is tested. The full cell reveals an operational voltage at 2.8 V and reversible capacity of about 138 mAhg−1 at 1 C.
      PubDate: 2015-07-01
       
  • Li 2 ZrO 3 -coated LiNi 0.6 Co 0.2 Mn 0.2 O 2 for high-performance cathode
           material in lithium-ion battery
    • Abstract: Abstract To improve the high-rate capacity and cycle ability, Li2ZrO3 was successfully coated on LiNi0.6Co0.2Mn0.2O2 materials via wet chemical method. The crystal structure and electrochemical properties of the bare and coated material are studied by X-ray diffractometry (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The XRD and SEM results indicated that the lattice structure of Li2ZrO3-coated materials was the same as the pristine one. Transmission electron microscopy showed that there was a thin Li2ZrO3 coating layer on the surface. Li2ZrO3-coating improves the rate performance and cycling stability. Within the cutoff voltage of 2.6–4.8 V, the 1 wt% Li2ZrO3-coated samples exhibited an initial discharge capacity of 190 mAh g−1 and with a capacity retention about 85 % after 50 cycles at 0.1 C. Minor Li2ZrO3 modification plays an important role to enhance the high-rate capability and cycle ability of LiNi0.6Co0.2Mn0.2O2.
      PubDate: 2015-06-06
       
 
 
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