电解液组成对中间相石墨微球电化学性能的影响

以2800℃热处理的煤焦油沥青基中间相石墨微球为锂离子二次电池负极材料,考察了中间相石墨微球在不同组成的电解质溶液中的电化学嵌脱锂性能.确定了试样在不同电解液中电极表面生成的SEI膜的化学组成和相对含量,剖析了共溶剂对SEI膜形成反应、膜组成和织构的影响.结果表明,在不同共溶剂的EC基电解液中,电极界面SEI膜形成的电位虽然不同,但SEI膜的化学组成基本相同,负极界面SEI膜的织构是决定电解液与电极材料相容性的关键.

Effects of Electrolyte Composition on the Electrochemical Properties of Graphitized Mesocarbon Microbeads

Coal-tar pitch based mesocarbon microbeads, graphitized at the maximum heat treatment temperature of 2 800 ℃, were employed as the negative electrode materials in lithium ion batteries. Electrochemical performances of the graphitized mesocarbon microbeads(MCMBs) in different electrolyte systems were examined. Chemical composition and relative content of surface electrode inhibition(SEI) film formed on the carbon electrode was determined. The influences of co-solvents on the SEI formation, composition and the film texture were discussed. The results show that, the SEI film consists mainly of the reduction products of EC molecules in EC-based electrolytes despite a certain difference exists in the onset of the SEI formation potential. The texture of SEI film is a deciding factor on the compatibilities of the electrolytes with the carbon electrode in lithium ion batteries.