Interface optimization mechanism and quantitative analysis of hybrid graphite anode for fast-charging lithium-ion batteries

Due to the inherent characteristics of traditional graphite anode material, its lithium diffusion kinetic is significantly constrained, easily leading to a noticeable capacity degradation during rapid charge/discharge cycling. Although modifying the graphite by mixing the hard carbon can effectively enhance its fast-charging performance, yet the underlying mechanism of improvement effect and structure design of interface are still needed to further investigate. To address this research gap, hard carbon-coated graphite (HCCG) material has been designed and synthesized through simple interface engineering, which is aimed to explore and elucidate the optimization mechanisms on fast-charging performance from the graphite interface perspective. According to the electrochemical calculations, the HCCG anode exhibits significant enhancements. Specially, its reversible lithium content is increased by approximately 8 % at various states of charge, its exchange current density is tripled, and its Tafel slope is reduced to one-quarter of the original graphite. Therefore, the HCCG maintains an impressive 86.89 % capacity retention and a high capacity of 202.3 mAh g