Mechanically Robust Polyimide Binder Realizes Stable and High Electrochemical Performance for Micro‐Silicon Anodes in Lithium‐Ion Batteries

Abstract Silicon anodes have been considered one of the most promising candidates for Li‐ion batteries due to their high theoretical specific capacity. However, the practical use of silicon anodes is impeded due to side reactions and volumetric change (from 300~400%) charge/discharge process. Binders played a crucial role in Li‐ion batteries by effectively mitigating the stress resulting from the volumetric expansion in silicon‐based anodes. Herein, we developed a mechanically stable polyimide binder PI‐CF 3 that introduced trifluoromethyl and hydroxyl groups for commercial microparticular silicon anodes. With a highest Young′s modulus of ~921.1 MPa, the binder presented the maximum resilience during the charging and discharging of Micro‐Si, integrating the morphology, and reducing the degree to which the electrode disrupted ion and electric pathways. Moreover, −OH and −CF 3 groups of the binder could potentially interact with oxide layer at the surface of silicon through hydron bonds, and thereby results in a cross‐linking network to improve interface stability during cycling. The as‐prepared PI‐CF 3 binder with excellent intrinsic mechanical and electro‐rich groups stabilizes the electrode structure and facilitates fast Li + transportation. Consequently, micro‐Si anode delivered initial specific capacity of 1838 mAh g −1 (at 0.6 A g −1 ), and at high mass (Si loading = 0.78 mg cm −2 ) these was retained about 1219 mAh g −1 after 330 cycles (only −0.061% capacity reduction per cycle).