Enhanced performance of graphite anode materials by AlF3 coating for lithium-ion batteries

The surface of commercial graphite powders has been successfully modified with a thin AlF3 coating via chemical precipitation for the first time. A thin (similar to 2 nm thick) and uniform AlF3 coating up to 2 wt% content is observed without an evident change in the bulk structure of graphite particles. An AlF3-coated graphite anode delivers a higher initial discharge capacity with much improved rate performance when compared to an uncoated graphite anode. Additionally, the AlF3-coated graphite anode demonstrates a much better cycle life than the uncoated graphite. After 300 cycles, batteries with anodes made from 1 wt% AlF3-coated graphite and uncoated graphite show capacity retentions of 92% and 81%, respectively. It is believed that a more stable and conductive solid electrode interphase layer is formed on AlF3-coated graphite particles, which enhances the performance of graphite anodes in lithium-ion batteries.