Nitrogen-doped carbon nanosheet coated multilayer graphite as stabilized anode material of potassium-ion batteries with high performances

Abstract By designing a multi-functional layer on the graphite surface, nitrogen-doped carbon nanosheet (NC) coated multilayer graphite (NC@MG) is synthesized as a promising anode material of potassium ion batteries (KIBs) with enhanced performances. Compared with the conventional graphite and multilayer graphite (MG), NC@MG exhibits a comparative flat discharge platform voltage of graphite anode and enhanced cyclic stability, rate performance, and specific capacity. It is indicated that the modified NC coating facilitates the formation of a stable SEI film on the NC@MG surface, which not only helps to improve the cycle stability, but also maximizes the embedding of K+ into the MG. The nitrogen elements in the NC also increase the electronic conductivity, which is beneficial to the rate performances of NC@MG. After 200 cycles at a current density of 50 mA g−1, the specific capacity of NC@MG is 252.7 mAh g−1; after 1000 cycles at 200 mA g−1, the specific capacity is still 215.7 mAh g−1. This work can not only obtain a stabilized graphite-based anode material of KIBs with enhanced electrochemical performances to date, but also provide a routine to modify and utilize the commercial graphite materials for KIBs.