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A non-solvent induced phase separation (NIPS) process was used to prepare a new kind of porous nanocomposite polymer electrolyte using glycerol as non-solvent for poly(vinylidene difluoride-co-hexafluoropropylene) copolymer. TiO 2 nanoparticles were incorporated by in situ hydrolysis of Ti ( OC 4 H 9)4 and dispersed uniformly in the polymer matrix. They affected the porous structure of the obtained nanocomposite polymer membranes (NCPMs). When the amount of TiO 2 arrived at 7.6 wt.%, the NCPM reached the maximum porosity of 70.5%. The resulting nanocomposite polymer electrolyte (NCPE) presents an ionic conductivity of up to 1.98 × 10-3 S · cm-1 at room temperature and an apparent activation energy for ion transport of 13.32 kJ · mol-1, suggesting its promising application in lithium ion batteries.

We report that various kinds of active sites on graphite surface including active hydrophilic sites markedly affect the electrochemical performance of graphite anodes for lithium-ion batteries under different humidity conditions. After depositing metals such as Ag and Cu by immersion and heat-treating, these active sites on the graphite surface were removed or covered and its electrochemical performance under the high humidity conditions was markedly improved. This suggests that lithium-ion batteries can be assembled under less strict conditions and provides a valuable direction toward lowering the manufacturing cost for lithium-ion batteries.To date, many kinds of anode materials for lithium-ion batteries have been studied. 1,2 However, graphitic carbons are still primarily available on the market, and this shows the importance of carbonaceous materials. A current research focus on the carbonaceous anode materials for lithium-ion batteries is the modification of graphite by, e.g., mild oxidation, deposition of metals or their oxides, coating with polymers, and other kinds of carbons on the graphite surface. 1-12 Nevertheless, few studies are devoted to investigate the sensitivity of anode materials towards humidity. 13,14 It has long been realized that the electrochemical performance of carbon anode materials is more sensitive to humidity than that of cathodic ones. When the humidity is high, anode materials easily absorb water resulting in rapid fading of the reversible capacity. Unfortunately, the water content in a manufacturing facility is very difficult to maintain at a desirably low level of essentially 0 ppm. If sensitivity of anode materials to humidity can be decreased, the requirements for controlling the atmosphere in the manufacturing unit will be lowered and lithium-ion batteries can be produced under less demanding conditions.In this paper, the sensitivity of graphitic carbon with hydrophilic active sites to humidity was studied, then the graphite surface was modified by covering or removing the surface active sites with deposited metals and the electrochemical performance of the composites prepared under high humidity condition was investigated. ExperimentalA natural graphite from mild oxidation ͑designated as LS17, d 002 3.351 Å, L c 120 Å and average particle size 17 m͒ as described in Ref. 8 was used for this study. Capacity measurements were performed as follows. A mixture of graphitic material and 5 wt % ͑based on the graphite͒ polyvinylidene fluoride ͑binder͒ was pressed into pellets with a diameter of ca. 1 cm. After drying under vacuum at 120°C overnight, the pellets were kept in an argon glove box at different humidities ͑Ͻ100 ppm and about 1000 ppm͒ for 1 h; later they were assembled into model cells under the same humidity conditions as the working electrode. Lithium foil was used as the counter and reference electrode, a solution of 1 M LiClO 4 in EC/ DEC ͑v/v = 3:7͒ as the electrolyte and a homemade porous polypropylene film as the separator. Electrochemical performance was measured g...

Composite polymer electrolytes (CPE) for lithium ion batteries are reported. Initially, nano-TiO 2 was modified by coating with a layer of poly(methyl methacrylate) (PMMA) by emulsion polymerization. CPE with this modified nano-TiO 2 were then prepared by the in situ copolymerization of poly(methyl methacrylate-acrylonitrile) (P(MMA-AN)). Morphology, thermal, electrochemical, and spectroscopic measurements were used to characterize the electrolytes. The PMMA-coated nano-TiO 2 was well dispersed in the polymer matrix due to the PMMA coating layer making the nanoparticles hydrophobic to effectively avoid the aggregation of the nanoparticles. The homogeneous CPEs of this PMMA-coated nano-TiO 2 have better thermal tolerance, higher ionic conductivity, and wider electrochemical stability, thus providing a practical route to improved polymer electrolytes.

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