Preparation and Performance of Silicon-Pyrolytic Carbon-Graphite Composite as Anode Material for Lithium-Ion Batteries

Silicon-pyrolytic carbon-graphite composite with different content of pyrolytic carbon has been synthesized through pyrolysis. Pitch has been used as precursor of pyrolytic carbon. Morphology, structure and electrochemical performance of materials have been tested and analyzed. The results showed that the mass of pitch decreased rapidly from 320 to 560 degrees C. The decrease of mass results from removal of hydrogen in pitch. Mass ratio between pyrolytic carbon and pitch was about 65% through pyrolysis process. In silicon-pyrolytic carbon-graphite composite, silicon particles were dispersed on the surface of graphite. Pyrolytic carbon covered silicon particles, and enhanced the interface adhesion between silicon particles and graphite. Appropriate content of pyrolytic carbon could increase the discharge capacity and improve the cycle stability of composite while excessive content of pyrolytic carbon could not further enhance discharge capacity.