Designing an Organic–Inorganic Composite Binder for High-Performance Si-Based Anodes

Silicon-based materials are promising candidate anodes for next-generation lithium-ion batteries owing to their high specific capacity. However, their large volume variation during cycling leads to rapid capacity decay. In this work, an organic–inorganic composite binder (CMP) based on carboxymethyl chitosan (CMCS) with sodium tripolyphosphate (STPP) is designed to alleviate the volume change of silicon-based anodes and maintain electrode stability. Nanoindentation and atomic force microscopy (AFM) confirm that the CMP binder significantly enhances the mechanical strength of the silicon oxide (SiOx)-based electrode. This improvement contributes to a stabilized electrode interface and a more uniform solid electrolyte interphase (SEI). As a result, the SiOx@CMP electrode delivers a high specific capacity of 1002.7 mAh g–1 after 400 cycles at 0.5 A g–1. Moreover, when applied in nanosilicon electrodes, the Si@CMP electrode exhibits excellent long-term cycling stability, with a capacity of 1700.68 mAh g–1 after 150 cycles at 1 A g–1. The proposed organic–inorganic composite binder strategy presents a promising solution for mitigating capacity decay in high-capacity silicon-based anodes.