A Robust Network Sodium Carboxymethyl Cellulose-Epichlorohydrin Binder for Silicon Anodes in Lithium-Ion Batteries

Abstract

Silicon (Si), as an ideal anode component for lithium-ion batteries, is susceptible to substantial volume changes, leading to pulverization and excessive electrolyte consumption, ultimately resulting in a rapid decline in the cycle stability. Herein, a new sodium carboxymethyl cellulose-epichlorohydrin (CMC-ECH) binder featuring a three-dimensional (3D) network cross-linked structure is synthesized by a simple ring-opening reaction, which can effectively bond the Si anode through abundant covalent and hydrogen bonds to mitigate its pulverization. Benefitting from the merits of the CMC-ECH binder, the electrochemical performance is significantly enhanced compared to the CMC binder. The CMC-ECH binder is applied to Si anodes, a specific capacity of 1054.2 mAh g^-1 can be maintained at 0.2 C following 200 cycles under an elevated Si mass loading of around 1.0 mg cm^-2, and the corresponding capacity retention is 65.6%. In the case of the LiFePO₄//Si@CMC-ECH full battery, the cycle stability exhibits a substantial enhancement compared with the LiFePO₄//Si@CMC full battery. Furthermore, the CMC-ECH binder demonstrates compatibility with micron-Si anode materials. Based on the above, we have successfully developed a facilely prepared water-based CMC-ECH binder that is suitable for Si and micron-Si anodes in lithium-ion batteries.