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    - CHEMICAL ENGINEERING (151 journals)
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    - ENGINEERING (1119 journals)
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ENGINEERING (1119 journals)            First | 2 3 4 5 6 7 8 9 | Last

International Journal of Intelligent Engineering Informatics     Hybrid Journal  
International Journal of Intelligent Systems and Applications in Engineering     Open Access   (Followers: 1)
International Journal of Lifecycle Performance Engineering     Hybrid Journal  
International Journal of Machine Tools and Manufacture     Hybrid Journal   (Followers: 4)
International Journal of Manufacturing Research     Hybrid Journal   (Followers: 7)
International Journal of Manufacturing Technology and Management     Hybrid Journal   (Followers: 9)
International Journal of Materials and Product Technology     Hybrid Journal   (Followers: 4)
International Journal of Mathematical Education in Science and Technology     Hybrid Journal   (Followers: 6)
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: 3)
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: 4)
International Journal of Navigation and Observation     Open Access   (Followers: 5)
International Journal of Network Management     Hybrid Journal  
International Journal of Nonlinear Sciences and Numerical Simulation     Full-text available via subscription   (Followers: 1)
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: 8)
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: 3)
International Journal of Polymer Science     Open Access   (Followers: 16)
International Journal of Precision Engineering and Manufacturing     Hybrid Journal   (Followers: 7)
International Journal of Precision Technology     Hybrid Journal  
International Journal of Pressure Vessels and Piping     Hybrid Journal   (Followers: 2)
International Journal of Production Economics     Hybrid Journal   (Followers: 10)
International Journal of Quality and Innovation     Hybrid Journal   (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: 4)
International Journal of Renewable Energy Technology     Hybrid Journal   (Followers: 7)
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: 1)
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: 2)
International Journal of Spray and Combustion Dynamics     Full-text available via subscription   (Followers: 5)
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 Assurance Engineering and Management     Hybrid Journal  
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 2)
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: 4)
International Journal of Thermodynamics     Open Access   (Followers: 1)
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: 4)
International Journal of Vehicular Technology     Open Access   (Followers: 1)
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: 5)
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  
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 2)
Irrigation and Drainage Systems     Hybrid Journal  
ISA Transactions     Full-text available via subscription  
ISRN - International Scholarly Research Notices     Open Access   (Followers: 69)
ISRN Signal Processing     Open Access  
IT Professional     Full-text available via subscription   (Followers: 2)
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 1)
Journal of Advanced Manufacturing Systems     Hybrid Journal   (Followers: 8)
Journal of Aerosol Science     Hybrid Journal   (Followers: 2)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 111)
Journal of Alloys and Compounds     Hybrid Journal   (Followers: 6)
Journal of Analytical and Applied Pyrolysis     Hybrid Journal   (Followers: 3)
Journal of Analytical Science & Technology     Open Access   (Followers: 4)
Journal of Analytical Sciences, Methods and Instrumentation     Open Access   (Followers: 1)
Journal of Applied Analysis     Full-text available via subscription  
Journal of Applied and Industrial Sciences     Open Access  
Journal of Applied Logic     Full-text available via subscription  
Journal of Applied Physics     Hybrid Journal   (Followers: 138)
Journal of Applied Probability     Full-text available via subscription   (Followers: 6)
Journal of Applied Research and Technology     Open Access  

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Journal Cover Ionics
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1862-0760 - ISSN (Online) 0947-7047
     Published by Springer-Verlag Homepage  [2209 journals]   [SJR: 0.522]   [H-I: 25]
  • Surface modifications of electrode materials for lithium-ion batteries:
           status and trends
    • Abstract: Abstract The research on the electrodes of Li-ion batteries aims to increase the energy density and the power density, improve the calendar and the cycling life, without sacrificing the safety issues. A constant progress through the years has been obtained owing to the surface treatment of the particles, in particular the coating of the particles with a layer that protects the core region from side reactions with the electrolyte, prevents the loss of oxygen, and the dissolution of the metal ions in the electrolyte, or simply improve the conductivity of the powder. The purpose of the present work is to review the different surface modifications that have been tried in the past for the different electrodes that are currently commercialized, or considered as promising, including the three families of positive electrodes (lamellar, spinel, and olivine families) and the three negative electrodes (carbon, Li4Ti5O12, and silicon). The role of the different coats used to improve either the surface conductivity, or the thermal stability, or the structural integrity is discussed. The limits in the efficiency of these different coats are also analyzed along with the understanding of the surface modifications that have been proposed.
      PubDate: 2014-06-01
  • Fabrication of highly selective PVA-g-GO/SPVA membranes via cross-linking
           method for direct methanol fuel cells
    • Abstract: Abstract Organic/inorganic composite membranes were prepared using sulfonated poly(vinyl alcohol) (SPVA), mixed and cross-linked with different amounts of poly(vinyl alcohol)-grafted graphene oxide (PVA-g-GO). The introduction of PVA-g-GO to the membranes not only reduced the methanol permeability but also positively affected the mechanical properties: Increasing the PVA-g-GO content increased the blocking effect of GO. The PVA-g-GO/SPVA membranes were cross-linked with glutaraldehyde, resulting in the formation of cross-linking chains within the matrix, as well as between the matrix and the filler. Therefore, the microstructure of the PVA-g-GO/SPVA cross-linking membrane was different from that of the existing membranes. This structure also reduced the methanol permeability. The composite membranes exhibited proton conductivities ranging from 0.0141 to 0.0319 S/cm at 60 °C, and low methanol permeability ranging from 3.13 × 10−7 to 1.53 × 10−7 cm2 s−1 at 25 °C.
      PubDate: 2014-06-01
  • Structural and electrical properties of nanostructured cerium phosphate
    • Abstract: Abstract Cerium phosphate nanomaterials with different morphologies and sizes were synthesized via a hydrothermal process at 150 °C using cetyl-trimethyl-ammonium-bromide and ethylene-diamine-tetra acid as surfactants. The obtained samples were characterized by X-ray diffraction and a scanning electron microscope. A possible growth mechanism was proposed to reveal the formation process. The structural properties and the electrical conductivities of CePO4 nanomaterials were studied. The activation energies were obtained from Arrhenius plots where E a = 1.06 eV. The ac conductivity at different temperatures for CePO4 nanomaterials showed frequency independence in the lower frequency range. The dielectric measurements were carried out as a function of frequency and temperature. Variation of the dielectric properties and the ac conductivity with frequency revealed that the dispersion is due to a Maxwell-Wagner type of interfacial polarization in general.
      PubDate: 2014-06-01
  • Three-dimensional carbon fiber as current collector for lithium/sulfur
    • Abstract: Abstract Ni foam and carbon fiber cloth were tested as three-dimensional (3D) current collectors for a sulfur/polypyrrole composite cathode in lithium batteries. The cell with the carbon fiber current collector has exhibited remarkably enhanced electrochemical performance compared with its Ni foam counterpart, delivering a high initial capacity of 1,278 mAh g−1 and maintaining a discharge capacity at 810 mAh g−1 after 40 cycles at 0.06 C. Furthermore, the carbon fiber-based cell demonstrated a better rate capability and delivered a highly reversible discharge capacity of 397 mAh g−1 after 50 cycles at 0.5 C, representing an increase of 194 mAh g−1 compared to the Ni foam counterpart. The electrochemical property investigations along with scanning electron microscope studies have revealed that the carbon fiber current collector possesses a three-dimensional network structure, provides an effective electron conduction path, and minimizes the loss of electrical contact within the deposited cathode material during cycling. These results indicate that the carbon fiber cloth can be used as a promising, effective, and inexpensive current collector for Li/S batteries.
      PubDate: 2014-06-01
  • Ion-isotopic exchange reaction kinetics using Duolite ARA-9366B and
           Indion-AGR resins
    • Abstract: Abstract Radiotracer isotopic technique as an effective analytical tool was used to study the kinetics of ion-isotopic exchange reactions in the nuclear- and nonnuclear-grade anion exchange resins Duolite ARA-9366B and Indion-AGR. On the basis of kinetic data, specific reaction rate (per minute), amount of ion exchanged (millimoles), initial rate of iodide ion exchange (millimoles per minute), and log K d values were calculated for the two resins. It was observed that under identical experimental conditions of 35.0 °C, 1.000 g of ion exchange resins, and 0.002 mol/L of labeled iodide ion solution, the values calculated were 0.200 min−1, 0.278 mmol, 0.056 mmol/min, and 9.6, respectively, for Duolite ARA-9366B resin, which were higher than 0.102 min−1, 0.216 mmol, 0.022 mmol/min, and 5.7, respectively, for Indion-AGR resins. An identical trend was observed for the two resins during bromide ion-isotopic exchange reaction. The overall results indicate that under identical experimental conditions, Duolite ARA-9366B resins show superior performance than Indion-AGR resins. The results of the present experimental work have demonstrated that the radioanalytical technique used here can be successfully applied for the characterization of different ion exchange resins so as to evaluate their performance under various process parameters.
      PubDate: 2014-06-01
  • Effects of solvent composition on the electrochemical performance of
           Li2FeSiO       class="a-plus-plus">4/C cathode materials synthesized via
           tartaric-acid-assisted sol–gel method
    • Abstract: Abstract Li2FeSiO4/C composites were synthesized via a tartaric-acid-assisted sol–gel method with ethanol and ethylene glycol (EG) as mixed solvents. Effects of solvent composition on the physical properties and electrochemical performances of Li2FeSiO4/C were studied. The materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical performances of Li2FeSiO4/C were evaluated by galvanostatic charge–discharge and electrochemical impedance spectra (EIS) measurements. The results show that the addition of EG to ethanol solvent during preparation has a positive effect on the electrochemical performance of Li2FeSiO4/C. The sample synthesized using EG–ethanol with the volume ratio of 2:7 has the best electrochemical performance. It delivers an initial discharge capacity of 105 mAh g−1 at C/16. AC impendence investigation shows that Li2FeSiO4/C synthesized using the optimal EG/ethanol volume ratio has lower resistance of electrode/electrolyte interface and higher lithium-ion diffusion coefficient than that synthesized using ethanol as solvent.
      PubDate: 2014-06-01
  • Preparation and comparative structural properties of porous SnO       class="a-plus-plus">2 microrods and submicrorods
    • Abstract: Abstract A facile two-step approach has been used for the synthesis of porous SnO2 rods: the initial room-temperature precipitation of precursor SnC2O4 and its subsequent thermal decomposition at 550 °C. Both the as-obtained porous SnO2 microrods (length ∼10.0 ± 3.5 μm, diameter ∼1.1 ± 0.4 μm) and submicrorods (length ∼5.8 ± 1.9 μm, diameter ∼0.4 ± 0.1 μm) are the crystalline mixtures of major tetragonal and minor orthorhombic crystal phases, showing a tetragonal fraction of 84.7 and 87.0 %, respectively. When applied as a lithium-ion battery anode, the porous submicrorods (specific surface area ∼13.6 m2 g−1) can deliver an initial discharge capacity of 1,730.7 mAh g−1 with a high coulombic efficiency of 61.6 % and show the 50th discharge capacity of 662.8 mAh g−1 at 160 mA g−1 within a narrow potential range of 10.0 mV to 2.0 V. Similarly, even the anode of porous microrods (specific surface area ∼11.8 m2 g−1) can still exhibit an initial discharge capacity of 1,661.1 mAh g−1 at 160 mA g−1 with a coulombic efficiency of 60.9 %. Regardless of the polymorphic nature, the acquired porosity may only alleviate the huge volume change of anodes for the first cycle; thus, the structural parameters of average size and specific surface area can be feasibly associated with the enhanced lithium storage capability. Anyway, these indicate a facile oxalate precursor method for the controlling synthesis and high performance of rodlike SnO2 for lithium-ion batteries.
      PubDate: 2014-06-01
  • Electrochemical performances of a novel lithium bis(oxalate)borate-based
           electrolyte for lithium-ion batteries with LiFePO       class="a-plus-plus">4 cathodes
    • Abstract: Abstract Lithium bis(oxalate)borate (LiBOB) is a promising salt for lithium-ion batteries. However, it is necessary to exert the electrochemical performance of LiBOB by the appropriate solvent. With dimethyl sulfite (DMS) as mixed solvents, the electrochemical behavior of γ-butyrolactone (GBL) with LiBOB is studied in this paper. It shows that LiBOB-GBL/DMS electrolyte has high oxidation potential (>5.3 V) and satisfactory conductivities. When used in lithium and mesophase carbon microbead cells, the novel electrolyte exhibits not only excellent film-forming characteristics but also low impedances of the interface films. Besides, when used in LiFeO4/Li cells, compared to the cell with the electrolyte system of 1 mol L−1 LiPF6–ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1, v/v), LiBOB-based electrolyte exhibits several advantages, such as more stable cycle performance at room temperature and higher mean voltage.
      PubDate: 2014-06-01
  • Hydrothermal synthesis and electrochemical performance studies of Al       class="a-plus-plus">2O       class="a-plus-plus">3-coated LiNi       class="a-plus-plus">1/3Co       class="a-plus-plus">1/3Mn       class="a-plus-plus">1/3O       class="a-plus-plus">2 for lithium-ion batteries
    • Abstract: Abstract LiNi1/3Co1/3Mn1/3O2 nanocrystallites were synthesized by a one-step hydrothermal method, and uniform second particles were formed by a subsequent calcination process. X-ray diffraction results indicate that the as-synthesized material can be indexed by α-NaFeO2 layered structure with R-3 m space group. The results of Rietveld refinements show the I 003/I 104 value of the material is 2.032, and the nanostructured material presents low cation mixing, small cell volume, and a consequent suppression of lattice strain. The rate performances of the as-synthesized material can be further improved by coating Al2O3. The discharging capacity of Al2O3-coated material reaches 154.4 mAh g−1, and the capacity retention maintains 80.3 % after 50 cycles at 5 C in the voltage range of 2.5 to 4.5 V, while those of the bare one is only 139.0 mAh g−1 and 71.6 %, respectively. The transmission electron microcopy observation shows no zigzag layer exists on the surface of particle after cycles for Al2O3-coated LiNi1/3Co1/3Mn1/3O2. Compared to bare LiNi1/3Co1/3Mn1/3O2, the de-intercalation potential difference before and after cycles of Al2O3-coated one is smaller. This indicates that Al2O3 coating can reduce the electrochemistry polarization in the electrode bulk.
      PubDate: 2014-06-01
  • A novel TiO2
           nanoparticles/nanowires composite core with ZrO       class="a-plus-plus">2 nanoparticles shell coating
           photoanode for high-performance dye-sensitized solar cell based on
           different electrolytes
    • Abstract: Abstract The novel TiO2 nanopartilces/nanowires (TNPWs) composite with ZrO2 nanoparticles (ZNPs) shell-coated photoanodes were prepared to fabricate high-performance dye-sensitized solar cell (DSSC) based on different types of electrolytes. Hafnium oxide (HfO2) is a new and efficient blocking layer material applied over the TNPWs-ZNPs core-shell photoanode film. TiO2 nanoparticles (TNPs) and TiO2 nanowires (TNWs) were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). DSSCs were fabricated using the novel photoanodes with an organic sensitizer D149 dye and different types of electrolytes namely liquid electrolyte, ionic liquid electrolyte, solid-state electrolyte, and quasi-solid-state electrolyte. The DSSC-4 made through the novel core-shell photoanode using quasi-solid-state electrolyte showed better photocurrent efficiency (PCE) as compared to the other DSSCs. It has such photocurrent-voltage characteristics: short circuit photocurrent (Jsc) = 19 mA/cm2, the open circuit voltage (Voc) = 650 mV, fill factor (FF) = 65 %, and PCE (η) = 8.03 %. The improved performance of DSSC-4 is ascribed to the core-shell with blocking layer photoanode could increased electron transport and suppressed recombination of charge carriers at the TNPWs-ZNPs/dye/electrolyte interface.
      PubDate: 2014-06-01
  • Effect of Mn doping on electrochemical properties of Li       class="a-plus-plus">2FeSiO       class="a-plus-plus">4/C cathode materials based on a
           vacuum solid-state method
    • Abstract: Abstract Li2Fe1−x Mn x SiO4/C (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) are prepared by a vacuum solid-state reaction of SiO2, CH3COOLi·2H2O, FeC2O4·2H2O, and Mn(CH3COO)2·4H2O. The crystalline structures, morphologies, and electrochemical performances are analyzed contrastively by X-ray diffraction (XRD), scanning electron microscopy, galvanostatic charging–discharging, and electrochemical impedance spectroscopy (EIS). The XRD and EIS results prove that Mn doping may be beneficial to the battery performances of Li2FeSiO4 materials, by reducing the crystallite sizes, decreasing transfer impedance (R ct), and increasing Li-ion diffusion coefficient (D Li+). However, the galvanostatic charge–discharge results indicate that only Li2Fe0.8Mn0.2SiO4/C shows the improved performance; its initial discharge capacity can reach to 190.7 mAh g−1. All things considered, the increased impurities after Mn doping, decided by reference intensity ratio (RIR) method, seem to impose more negative effects on the Li2Fe1−x Mn x SiO4/C performances. Under this premises, the Mn-doped content is particularly important for Li2FeSiO4 materials prepared by the vacuum solid-state method.
      PubDate: 2014-06-01
  • Ethylene sulfate as film formation additive to improve the compatibility
           of graphite electrode for lithium-ion battery
    • Abstract: Abstract Ethylene sulfate (DTD) is investigated as a novel film formation electrolyte additive for graphite anode material in lithium-ion battery. The CV results reveal that DTD is reduced prior to ethylene carbonate (EC) at the interface between graphite and electrolyte, while it cannot prevent the sustained reduction of propylene carbonate (PC) when the amount of DTD is lesser than 3 wt% in the PC-based electrolyte. XPS analyses demonstrate that the reduction products of DTD, Li2SO3, and ROSO2Li are formed at the surface of graphite in the EC-based electrolyte, which is beneficial to lower the interfacial resistance as suggested by the EIS results. In addition, SEM images show a smoother and homogeneous surface film at the surface of graphite when DTD is incorporated into the electrolyte. Consequently, the Li/graphite half cells cycled in EC-based electrolyte containing DTD exhibit higher specific capacity and improved cycling capability than that without DTD.
      PubDate: 2014-06-01
  • Synthesis of flower-like Li3V       class="a-plus-plus">2(PO       class="a-plus-plus">4)       class="a-plus-plus">3/C cathode with mixed morphology for
           advanced lithium-ion batteries
    • Abstract: Abstract A rheological phase-assisted ball milling method was developed to synthesize of flower-like Li3V2(PO4)3/C composites consisting of nanofibers and nanoplate porous microstructure. The flower-like Li3V2(PO4)3/C composite delivered specific capacities of 120 and 108 mAh g−1 at 0.5 and 10 C rates, respectively. A capacity retention of 99.5 % was sustained after 100 cycles at a 10-C cycling rate. The remarkable performance was attributed to the porous nanostructures that provide short electron/ion diffusion distance and large electrode/electrolyte contact area.
      PubDate: 2014-06-01
  • Influence of coated MnO2 content
           on the electrochemical performance of Li       class="a-plus-plus">1.2Ni       class="a-plus-plus">0.2Mn       class="a-plus-plus">0.6O       class="a-plus-plus">2 cathodes
    • Abstract: Abstract Layered cathode material Li1.2Ni0.2Mn0.6O2 has been synthesized using a coprecipitation method and coated by MnO2 with varying amounts (1, 3, 5, and 9 wt%). The physical properties and electrochemical performances of the materials are characterized by XRD, SEM, charge/discharge tests, cycle life, and rate capability tests. XRD patterns show that the pristine and coated Li1.2Ni0.2Mn0.6O2 powders exhibit layered structure. The discharge capacities and coulombic efficiencies of Li1.2Ni0.2Mn0.6O2 in the first cycle have been improved and increase with the increasing content of coated MnO2. The 9 wt% MnO2-coated Li1.2Ni0.2Mn0.6O2 delivers 287 mAhg−1 for the first discharge capacity and 86.7 % for the first coulombic efficiency compared with 228 mAhg−1 and 65.9 % for pristine Li1.2Ni0.2Mn0.6O2. However, the 5 wt% MnO2-coated Li1.2Ni0.2Mn0.6O2 shows the best capacity retention (99.9 % for 50 cycles) and rate capability (88.6 mAhg−1 at 10 C), while the pristine Li1.2Ni0.2Mn0.6O2 only shows 91.5 % for 50 cycles and 25.3 mAhg−1 at 10 C. The charge/discharge curves and differential capacity vs. voltage (dQ/dV) curves show that the coated MnO2 reacts with Li+ during the charge and discharge process, which is responsible for higher discharge capacity after coating. Electrochemical impedance spectroscopy results show that the R ct of Li1.2Ni0.2Mn0.6O2 electrode decreases after coating, which is responsible for superior rate capability.
      PubDate: 2014-06-01
  • Differential pulse anodic stripping voltammetric determination of Hg       class="a-plus-plus">2+ at poly(Eriochrome Black
           T)-modified carbon paste electrode
    • Abstract: Abstract The electrochemical behavior of Hg2+ was investigated in poly(Eriochrome Black T)-modified carbon paste electrode (CPE) using cyclic voltammetry (CV). Poly(Eriochrome Black T) was prepared in an alkaline medium on the surface of the CPE using a solution of Eriochrome Black T with the CV technique. The electrochemical impedance study revealed a better charge transfer kinetics at the modified electrode. The effects of variation of the experimental conditions, such as the concentration of electrolytes, pH, deposition time, and the deposition potential, which maximize current efficiency were studied. The optimum response of Hg2+ was observed in 1.0 M KCl solution. The differential pulse anodic stripping voltammetric technique was employed successfully to detect Hg2+, which gave a good linear response at low concentration levels of Hg2+. The detection limit was found to be 2.2 × 10−10 M (S/N = 3), which is comparable with that achieved in multiwall carbon nanotube-modified electrode. The remarkable electroanalytical performance of the modified electrode makes it amenable to employ it successfully as an electrochemical sensor for the determination of hazardous pollutant Hg2+ in environmental samples.
      PubDate: 2014-06-01
  • Structural and electrochemical properties of LiFe       class="a-plus-plus">1 − 3       class="a-plus-plus">x/2Bi       class="a-plus-plus"> x
           PO4/C synthesized by
    • Abstract: Abstract In this study, LiFe1 − 3x/2Bi x PO4/C cathode material was synthesized by sol–gel method. From XRD patterns, it was found that the Bi-doped LiFePO4/C cathode material had the same olivine structure with LiFePO4/C. SEM studies revealed that Bi doping can effectively decrease the particle sizes. It shortened Li+ diffusion distance between LiFePO4 phase and FePO4 phase. The LiFe0.94Bi0.04PO4/C powder exhibited a specific initial discharge capacity of about 149.6 mAh g−1 at 0.1 rate as compared to 123.5 mAh g−1 of LiFePO4/C. EIS results indicated that the charge-transfer resistance of LiFePO4/C decreased greatly after Bi doping.
      PubDate: 2014-05-23
  • Salt-leached microporous membranes for lithium batteries
    • Abstract: Abstract Poly(vinylidene fluoride) (PVDF)/sodium hydrogen carbonate (NaHCO3)-based microporous polymer membranes were prepared by salt leaching. In this study, lithium-trifluoromethane sulfonate (LiCF3SO3) was used by dissolving it in solvents like propylene carbonate (PC), dimethyl carbonate (DMC), and diethylene carbonate (DEC). Microporous polymer electrolytes (MPE) were obtained from their porous polymer membranes when immersed in 0.1 M LiCF3SO3 in a mixture of PC/DMC/DEC (2:2:1) electrolyte solution. The membranes were characterized by electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), chronopotentiometry (CP), chronocoulometry (CC), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). The electrochemical stability window of the membrane has been evaluated with LSV using the triple electrode system. Ac conductivities of the Li salt containing membranes were found to be 1.34 × 10−5 S cm−1 (GPE100) and 2.69 × 10−6 S cm−1 (GPE25).
      PubDate: 2014-05-21
  • Preparation and electrochemical properties of EG/Fe       class="a-plus-plus">2O       class="a-plus-plus">3/C composite
    • Abstract: Abstract The present paper deals with the studies concerning electrochemical properties of the expanded graphite/iron oxide/carbon (EG/Fe2O3/C) composite produced by deep cathodic reduction. The electrochemical activity of EG/Fe2O3/C composite was investigated in alkaline solution by cyclic voltammetry technique. Electrochemical features of EG/Fe2O3/C were found to be strongly influenced by the conditions under which the measurements were performed. The interpretation of electrochemical measurements was supported by the scanning electron microscope (SEM) observation revealing the appearance of carbon fibers of a different diameter as the main component of the carbon layer within the examined EG/Fe2O3/C composite. The X-ray diffraction (XRD) and energy dispersive spectrometry (EDS) analysis have confirmed the presence of Fe2O3 layer within the EG/Fe2O3/C composite. Additionally, the latter analysis has provided information on changes within the chemical composition of EG/Fe2O3/C caused by electrochemical treatment.
      PubDate: 2014-05-21
  • Anomalous electrical properties in superionic (Ag       class="a-plus-plus"> x
           Cu1−       class="a-plus-plus">x )Br (       class="a-plus-plus">x = 0.5): ab initio study
    • Abstract: Abstract The electrical properties of superionic (Ag x Cu1−x )Br (x = 0.5), band structure and density of states, have been examined by ab initio calculation based on the density functional theory in comparison with solid CuBr in zinc blend structure. The charge transfer between ions has been discussed in relation with the occupation probability of Cu ion in superionic (Ag x Cu1−x )Br (x = 0.5).
      PubDate: 2014-05-17
  • Alkaline poly(vinyl alcohol)/poly(acrylic acid) polymer electrolyte
           membrane for Ni-MH battery application
    • Abstract: Abstract Alkaline polymer electrolyte membrane with high ionic conductivity of 0.019 S cm−1 at room temperature was prepared from poly(vinyl alcohol) and acrylic acid through solution polymerization. The structure and morphology of the membrane were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The electrochemical properties were measured by the alternating current impedance (AC impedance) and the cyclic voltammetry (CV) techniques. Simulated Ni-MH batteries using Mg-based hydrogen storage alloy produced by the hydriding combustion synthesis and mechanical milling (HCS + MM) technique as negative electrode were assembled by using the experimental PVA-PAA-KOH polymer membrane (polymer Ni-MH batteries) and 6 mol L−1 KOH aqueous (traditional Ni-MH batteries) as electrolytes, respectively. After 10 cycles, the capacity retention rate of the traditional Ni-MH battery was only 3.9 %, but the corresponding value of polymer Ni-MH battery was 14.7 %.
      PubDate: 2014-05-16
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