Carboxyl Function Group Introduced to Polyimide Binders for Silicon Anode Materials

Silicon has been considered as one of the most promising candidate anode material for Li-ion batteries due to its high theoretical specific capacity. Nevertheless, its low cycling performance due to the huge volume change during cycling hinders the commercial application of silicon anodes. Binders play a crucial role in Li-ion batteries and can effectively relieve the volumetric expansion stress of silicon anodes. Herein, we developed a polyimide binder with an introduced carboxyl group (PI-COOH). The introduced −COOH group can effectively bond with the oxide layer on the silicon surface through forming improved interface stability and then reducing the damage of the solid electrolyte interface film during cycling. Combined with the excellent intrinsic mechanical and thermodynamic properties of polyimide, the as-prepared PI-COOH binder significantly improved the cycling stability and rate performance of silicon anode.