Enhanced cycle performance of SiO-C composite anode for lithium-ion batteries

A silicon monoxide (SiO)-carbon composite prepared by ball-milling and pyrolysis is evaluated as an anode material for lithium-ion batteries. Electrochemical tests demonstrated that the first charge and discharge capacities of the material are about 1050 and 800 mAh g(-1), respectively, with a first-cycle efficiency of 76%. The disproportionation reaction of pure SiO into Si and SiO, during pyrolysis is confirmed by means of XRD and Si-29 MAS NMR. The cycle performance of this material shows an excellent reversible capacity retention of 710 mAh g(-1) over 100 cycles without any potential or capacity restrictions. This improved cycle performance is attributed to the stable microstructure, enhanced electrical contact afforded by the pyrolyzed carbon, and the amorphous phase transformation of the active material during cycling. (c) 2007 Elsevier B.V. All rights reserved.