Enhanced work function in hybrid hard carbon/graphite negative electrode builds thermally stable solid electrolyte interphase for lithium-ion batteries

The thickness of solid electrolyte interphase (SEI) significantly affects the graphite cycle-life of lithium-ion batteries (LIBs). However, decomposition of the electrolyte on the negative electrode surface accelerates the growth of SEI, particularly at high temperatures. Herein, a hybrid negative electrode with a high work function has been designed by incorporating hard carbon into graphite. The increase of the work function of the electrode effectively suppress electrons escape, thereby reducing the electrolyte decomposition and inhibiting the growth of SEI on the electrode surface. Additionally, hybrid electrodes also have the high lithium-ion diffusion efficiency that prevents lithium deposition on the negative electrode surface. Consequently, hybrid electrodes of the high work function significantly enhance electrochemical performance of LIBs during high-temperatures floating charge, due to the reduced growth of SEI. This strategy of developing a hybrid hard carbon/graphite negative electrode of high work function paves the way to suppress the growth of SEI and provides a new perspective for solving the failure of lithium ion batteries at high temperature floating charge.