The synergistic dual-layer coating of hard carbon and soft carbon enhances the lithium-ion storage capacity of graphite anode

With the increasing demand for high-performance lithium-ion batteries (LIBs) in electric vehicles and portable electronic devices, rapid charging and long cycle life have become primary focuses in LIBs research. However, the poor rate performance of graphite anode materials and the suboptimal lithium-ion transport rate have constrained the development of LIBs. Herein, we synthesize a graphite anode material with a dual-layer coating structure of hard carbon (HC) and soft carbon (C) (G@HC@C) using a straightforward pre-oxidation and carbonization method. The hard carbon layer is formed by high-temperature carbonization of pre-oxidized pitch, characterized by an expanded interlayer spacing that facilitates rapid lithium-ion insertion and enhances capacity. The soft carbon outer layer helps to mitigate volume expansion during charge-discharge cycles and prevents direct contact between the graphite and the electrolyte, thereby enhancing electrode stability. The G@HC@C electrode exhibits excellent rate performance (119.5 mAh g^-1 at 3 C) and maintains a cycle stability of 219.7 mAh g^-1 after 1000 cycles at 1 C. This work offers new insights and methods for modifying graphite anode materials in fast-charging LIBs.