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Carbon-coated LiMnSiO powders were synthesized by a citric acid-assisted sol-gel process, and their physical and electrochemical properties were characterized to assess their suitability as a cathode material in lithium-rechargeable batteries. Carbon was coated onto the LiMnSiO particles through the carbonization of polymeric materials that were caused by the addition of citric acid during the sol-gel process. The particle size and electrical conductivity of the LiMnSiO powders were found to be changed by varying the amount of citric acid added during the sol-gel process. XRD analysis showed that the quantity of impurities in LiMnSiO was decreased during the sol-gel process. The carbon coating led to an increase in conductivity and mean particle size by creating an electrical and physical connection between the particles. The discharge capacity of LiMnSiO with over 5 % carbon coating was significantly increased to ~125 mAh g compared to just ~3 mAh g for noncoated material. [ABSTRACT FROM AUTHOR]

Nanoporous Si was obtained by means of metal-assisted chemical etching. Li ion insertion-extraction was tested by voltammetric and galvanostatic electrochemical cycling in conventional 1 M LiPF ethylene carbonate/dimethyl carbonate EC/DMC and in 1 M LiTFSI 1-butyl-1-methyl-pyrrolidinium bis (trifluoromethyl) sulfonylimide [BMP] [TFSI] electrolytes. The nanoporous Si demonstrated high reversibility when cycled in 1 M LiPF EC/DMC electrolyte and showed superior activity compared to the non-structured sample. In contrast to the organic carbonate electrolyte, the material cycling in ionic liquid media showed reduced capacity and reversibility of the Li ion exchange. The latter results were discussed in terms of the high viscosity of the ionic liquid and ineffective cathodic passivation of the Si substrate in the ionic liquid-based electrolyte. Scanning electron microscopy imaging showed minor morphological changes due to the large volume change during Li insertion. No signs of crack formation and propagation were detected during the time span of the measurement. [ABSTRACT FROM AUTHOR]

This paper reported on a new gel polymer electrolyte (GPE) based on polyethylene (PE) non-woven fabric supported poly(acrylonitrile-vinyl acetate) (P(AN-VAc)/PE) membrane for lithium ion battery use. The preparation and performances of the P(AN-VAc)/PE membrane and its GPE based on 1 M LiPF in dimethyl carbonate/diethylene carbonate/ethylene carbonate (1:1:1 in volume) were investigated with a comparison of the unsupported P(AN-VAc) membrane. It is found that the P(AN-VAc)/PE membrane shows better mechanical strength and pore structure for electrolyte uptake than the P(AN-VAc) membrane, and subsequently the GPE based on P(AN-VAc)/PE exhibits higher ionic conductivity and electrochemical stability on cathode than the GPE based on P(AN-VAc). With the support of the non-woven fabric, the ionic conductivity of the GPE at room temperature increases from 1.4 to 3.8 mS cm, the oxidation decomposition potential of the GPE on a stainless steel is improved from 5.0 to 5.6 V (vs. Li/Li). The mesocarbon microbeads (MCMB)/LiMnO battery using P(AN-VAc)/PE as separator retains 94% of its initial discharge capacity after 100 cycles at C/2 rate, showing that the P(AN-VAc)/PE membrane is a possible alternative to the expensive separator for current liquid lithium ion battery. [ABSTRACT FROM AUTHOR]

The article evaluates the primary electrochemical performance of surface modified spherical graphite in relation to the distribution of conductive additive particles on the coated electrode material. It has been observed that the cycling behavior was influenced by the dispersion of conductive additive. The initial reversible capacity was greater than that of commercial synthetic graphite. Also, poor dispersion produced numerous white deposits.