Core-shell Si/C nanocomposite as anode material for lithium ion batteries*
Tao Zhang, Lijun Fu, Jie Gao, Lichun Yang, Yuping Wu, and Hoqing Wu
Department of Chemistry & Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433, China
Abstract: We report an effective method for the synthesis of a core-shell Si/C nanocomposite, and its application as anode material for lithium ion (Li-ion) batteries. Polyacrylonitrile (PAN)-coated Si nanoparticles are formed by emulsion polymerization, and this precursor is heat-treated under argon to generate a Si/C core-shell nanocomposite. The conductive carbon shell envelops the silicon nanoparticles and suppresses aggregation of the nanoparticles during cycling. Meanwhile, the carbon shell combines closely with the nanocores, and significantly enhances the kinetics of lithium intercalation and de-intercalation, as well as the apparent diffusion coefficient of Li-ions. Consequently, the core-shell Si/C nanocomposite exhibits better electrochemical performance than pure Si nanoparticles, indicating that this is a promising approach to improve cyclability and kinetics of nano-anode materials for Li-ion batteries.
Keywords: Li-ion batteries; anode; core-shell; Si/C; emulsion polymerization.
*Paper based on a presentation at the 15th International Symposium on Fine Chemistry and Functional Polymers (FCFP-XV) and the 1st International Symposium on Novel Materials and Synthesis (NMS-I), 17-20 October 2005, Shanghai, China. Other presentations are published in this issue, pp. 1803-1896.