Enhancement of the Cyclability of a Si Anode through Co3O4 Coating by the Sol–Gel Method

A nano-Si/Co3O4 core–shell nanostructured material has been successfully prepared using the sol–gel method. The reaction mechanism between Li and the nano-Si/Co3O4 core–shell nanostructured electrode was investigated by ex situ analyses. Metallic Co, Li21Si8, and amorphous Li2O phases were formed when fully lithiated, and an amorphous Si, Co3O4, and Co phases were identified after charge, indicating that the Co3O4 was partially reversible. The nano-Si/Co3O4 core–shell nanostructured electrode showed excellent cyclability, with a reversible capacity of ca. 850 mAh/g over 100 cycles.