Evaluation and performance improvement of Si/SiOx/C based composite as anode material for lithium ion batteries

The structure and electrochemical performances of Si/SiOx/C (SSC) and graphite-SSC composite (G-SSC) are evaluated in half cells and full cells as anode materials for lithium ion batteries. It is found that the SSC material shows a lithium storage capacity of 3 to 5 times higher than that of pure graphite while the G-SSC composite exhibits a desirable cycling stability (+80%@400cycles). Structural characterization reveals no particle cracks in the G-SSC composite. The Si particle is surrounded with lithium silicates, which provide protection against the electrolyte invasion and electrolyte decomposition but permits the Li+ ions to pass through. The graphite coating layer, on the other hand, acts as an electric conductive connector and volume buffer. These structural features make the SSC and G-SSC attractive as anode materials for high-performance commercial lithium ion batteries.