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

Silicon\n(Si), as an ideal anode component for lithium-ion batteries,\nis susceptible to substantial volume changes, leading to pulverization\nand excessive electrolyte consumption, ultimately resulting in a rapid\ndecline in the cycle stability. Herein, a new sodium carboxymethyl\ncellulose-epichlorohydrin (CMC-ECH) binder featuring a three-dimensional\n(3D) network cross-linked structure is synthesized by a simple ring-opening\nreaction, which can effectively bond the Si anode through abundant\ncovalent and hydrogen bonds to mitigate its pulverization. Benefitting\nfrom the merits of the CMC-ECH binder, the electrochemical performance\nis significantly enhanced compared to the CMC binder. The CMC-ECH\nbinder is applied to Si anodes, a specific capacity of 1054.2 mAh\ng<sup>–1</sup> can be maintained at 0.2 C following 200 cycles\nunder an elevated Si mass loading of around 1.0 mg cm<sup>–2</sup>, and the corresponding capacity retention is 65.6%. In the case\nof the LiFePO<sub>4</sub>//Si@CMC-ECH full battery, the cycle stability\nexhibits a substantial enhancement compared with the LiFePO<sub>4</sub>//Si@CMC full battery. Furthermore, the CMC-ECH binder demonstrates\ncompatibility with micron-Si anode materials. Based on the above,\nwe have successfully developed a facilely prepared water-based CMC-ECH\nbinder that is suitable for Si and micron-Si anodes in lithium-ion\nbatteries.