Surface‐Functionalized Graphite as Long Cycle Life Anode Materials for Lithium‐Ion Batteries

Abstract Graphite is the major anode material of commercial lithium‐ion batteries (LIBs), and thus improving its cycling stability is an effective approach to extend battery life. In this study, succinic anhydride group, methoxyethanol, and methoxypolyethylene glycol segments are chemically bonded to the surfaces of graphite particles by the Diels‐Alder and the subsequent esterification reactions. The synthesized functionalized graphites are excellent in water dispersibility. The electrochemical results indicate that the functionalization slightly reduces the initial coulombic efficiencies of the graphite anodes, but significantly changes the cycling stability and high C‐rate performance of the corresponding lithium‐ion cells. In particular, the cell based on the graphite functionalized by long‐chain polyethylene glycol exhibits an improvement of 24.1 % in cycle life compared with the pristine graphite. Further analysis shows that these trace organic groups change the properties of the solid‐electrolyte interface (SEI) layer depositing on the graphite surfaces, and therefore influence the performance of the cells.