Revealing Carbon Intermediate Structure and Functions for Carbon‐Coated Silicon Anodes

ABSTRACT The carbon coating of silicon‐based anodes has been proven effective in improving cycling stability, yet the real carbon protection structure and performance improvement mechanisms upon volume fluctuations of silicon during cycling have not yet been revealed. Herein, we discover an intermediate state of carbon coating named crazing carbon coating (a micro‐cracked network retaining mechanical integrity) during cycling by removing the solid electrolyte interphase (SEI) interference and quantifying carbon crack ratio on a carbon‐coated silicon oxide anode model. This intermediate structure is effective in preventing silicon electrochemical sintering through the mechanical confinement effect and inhibiting the conversion of active silicon oxide to an inactive silicon‐electrolyte composite by an oxygen isolation effect. This work opens the black box of the real effective carbon state during anode cycling, distinct from the conventional view of perfectly integral and fully collapsed carbon coating. Based on these findings, a program adjustment strategy is adopted to enable durable crazing carbon structure, and realise a stable operation over 700 cycles with a specific capacity of 1000 mAh g −1 and high retention of 99%. This study is expected to provide ideas for the mechanical design of future coating structures on silicon‐based anodes.