High capacity silicon/carbon composite anode materials for lithium ion batteries

Silicon/carbon composite materials are prepared by pyrolysis of pitch embedded with graphite and silicon powders. As anode for lithium ion batteries, its initial reversible capacity is 800-900 mAh/g at 0.25 mA/cm(2) in a voltage range of 0.02/1.5 V vs. Li. The material modification by adding a small amount of CaCO3 into precursor improves the initial reversibility (eta(1) = 84%) and suppresses the capacity fade upon cycling. A little higher insertion voltage of the composites than commercial CMS anode material improves the cell safety in the high rate charging process. (C) 2003 Published by Elsevier Science B.V.