A novel Si/C composite negative electrode for lithium ion batteries was obtained by pyrolyzing the mixture of polyvinyl chloride, nano-Si powder and fine artificial graphite particles. Nano-Si and fine graphite are dispersed in carbon uniformly. Electrochemical test shows the first cycle efficiency of the composite is about 84% and the reversible capacity is about 700 mAh·g~(-1). The capacity retention at the 30th cycle is more than 90% . In addition, the charge-discharge voltage plateau of the composite shifts toward positive direction for about 0.15V against that of the commercialized CMS negative electrode material, which is favorable for enhancing the charging rate and operating safety of the cell.

Key words: CARBON, COMPOSITE MATERIALS, LITHIUM ION, THERMOLYSIS, POLYVINYL CHLORIDE, BATTERIES