A Double Core-shell Structure Silicon Carbon Composite Anode Material for a Lithium Ion Battery

Silicon with high theoretical specific capacity is a promising anode material, but the poor electronic conductivity and excessive volume expansion hinder its practical application. In order to solve this problem, a novel double core-shell structure composite Si/G/C-CVD coated by pitch pyrolysis and CVD (Chemical Vapor Deposition) carbon has been prepared. In the Si/G/C-CVD composite, nano-silicon particles and pitch particles are embedded on the surface of graphite particles, then the second carbon layer via CVD is added. The double carbon layer can protect nano-silicon particles from direct exposure to the electrolyte and enhance the electrochemistry performance during the lithium intercalation/extraction process. The as-prepared Si/G/C-CVD composite demonstrates superior electrochemical performance, with enhanced specific reversible capacity (688.44 mAh g−1 at 100 mA g− 1), excellent rate performance (261.66 mAh g−1 even at the specific current of 1.6A g− 1) and good cycle performance with little fading (91% after 155 cycles).