Kazuma Hanai

Silicon/Carbon Composites as Anode Materials for Li-Ion Batteries

A silicon/carbon composite has been synthesized by two poly(vinyl chloride) (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.

Novel Composites Based on Ultrafine Silicon, Carbonaceous Matrix, and the Introduced Co-Milling Components as Anode Host Materials for Li-Ion Batteries

We report studies of the electrochemical behavior of the Si-M-C (M could be TiN, TiB 2 , graphite) composites, which were prepared from ballmilling silicon with the relatively inactive components and further followed a pyrolyzed poly(vinyl chloride) process. As lithium hosts, these composites showed large capacities of ca. 900 mAh g - 1 and good capacity retention. Research reveals that both the high-energy mechanical milling step and pyrolysis reaction play a key role in alleviating the morphology stress arising from silicon during cycling. A possible capacity decay mechanism with respect to such anode systems has also been investigated and discussed.