Nb 2 O 5 Modification Endows Fast Reaction Kinetics of Graphite Anodes for Lithium Ion Batteries

Commercial graphite anodes are widely used in lithium-ion batteries (LIBs) because of their low cost, high theoretical capacity, and low lithium intercalation/deintercalation potential. However, they suffer from inferior fast-charging performance and low-temperature performance, which are closely related to the composition of the solid electrolyte interphase (SEI). In this study, niobium pentoxide (Nb 2 O 5 ) was applied as a surface modification on graphite to modulate the interfacial composition, thereby enhancing the rate capability and the cycling life of the anode. The Nb 2 O 5 modification promotes the enrichment of PF 6 – anions in the solvation structure at the graphite interface, leading to lower desolvation energy and formation of an SEI richer in LiF. This LiF-rich SEI further enhances the transport through the interface, significantly improving the fast-charging performance. As a result, the Nb 2 O 5 -modified graphite electrode (Gr-Nb 2 O 5 ) delivers a specific capacity of 142.2 mA h g –1 at a high current density of 2000 mA g –1 and maintains 88.9% of its capacity after 2500 cycles. The modified graphite electrode also shows superior low-temperature performance. This work presents a simple, yet highly effective, strategy for optimizing graphite anodes through surface modification.