Electrochemical Characteristics of Silicon/Carbon Composite Anodes for Rechargeable Lithium Batteries

Abstract

Pyrolysis of polyvinyl chloride (PVC), in which fine graphite and silicon powders are homogeneously dispersed, produces a new type of silicon/carbon composite host for reversible lithium insertion and extraction. As anode material for lithium ion cells, its cycling capacity reaches about 700 mAh•g^-1 at 0.2 C charging rate. The capacity retention at the 30^th cycle is about 90% against the first cycle, much better than that of pure silicon electrode. A little higher insertion potential of the composites than commercialized Carbonaceous Mesophase Spherules (CMS, similar to MCMB) anode material enhances the charging rate capability and operating safety of the cells. The available capacity is about 450 mAh•g^-1 at 2 C rate for the composite, but it is below 100 mAh•g^-1 for CMS. This paper examines the influence of organic precursors, silicon particle size and current collectors on the electrochemical performance of the composite.