8C快充锂离子电池的石墨负极设计OA

To address the bottleneck of insufficient insertion kinetics of graphite anodes for fast charg-ing,this study achieves the 8 C fast-charging target through collaborative design of coke material se-lection,grinding,granulation,and soft carbon coating.Isotropic petroleum coke and anisotropic needle coke were selected and ground to 7.5 and 6.5 μm,respectively,to balance the kinetics of lithium-ion intercalation and diffusion between graphite layers.Subsequently,granulation and soft carbon coating were employed to further improve insertion kinetics.For the graphite design using pe-troleum coke with granulation and coating after graphitization(2.5％coating amount),soft carbon connections between primary particles resulted in low charge transfer impedance and small diffusion impedance,indicating excellent kinetic performance.However,its high-temperature storage and high-temperature cycling performance were poor.The design using petroleum coke with granulation be-fore graphitization and coating after graphitization(1.8％coating amount)demonstrated superior high-temperature storage performance,but its charge transfer impedance and diffusion impedance were high,leading to suboptimal kinetic performance.The design using needle coke with granulation before graphitization and coating after graphitization(1.8％coating amount)achieved the best over-all performance in terms of kinetics,storage,and cycling.When the capacity retention rate decayed to 80％,the fast-charging cycling and high-temperature cycling trends reached 4 000 and 1 500 cycles,respectively.This study provides design insights for the development of graphite materials for 8 C and higher-rate fast charging.