Silicon/carbon composites as anode materials for Li-ion batteries

A silicon/carbon composite has been synthesized by two poly(vinylchloride) (PVC) pyrolysis reactions, combined with an intervening high-energy mechanical milling (HEMM) step. As lithium storage host, the composite demonstrates high initial coulombic efficiency of 82% and a large capacity at ca. 900 mAh g(-1) over 40 cycles. Controlling Li-insertion level at 600 mAh g(-1) can greatly extend the cycles to over 100. Another composite prepared by ballmilling a mixture of graphite and silicon and followed by a PVC pyrolysis process also shows both good capacity and capacity retention. (C) 2004 The Electrochemical Society.