Three-Dimensional Cross-Linked Carboxymethyl Chitosan Binder for Si/C Anodes: Enhancing Cycling Stability and Performance in High-Energy Lithium-Ion Batteries

Abstract The silicon-carbon (Si/C) anode offers a significantly higher theoretical specific capacity compared to conventional graphite anodes, while also demonstrating reduced volume expansion and enhanced cycling stability compared to pure silicon anodes. Consequently, Si/C anodes have attracted considerable attention as promising candidates for next-generation high-energy lithium-ion battery anode materials. However, volume expansion remains a critical challenge, leading to the detachment of active materials from the current collector (copper foil) and adversely affecting cycling performance. In this study, we introduce diglycidyl ether (EG) as a cross-linking agent to synthesize a novel three-dimensional cross-linked carboxymethyl chitosan (CCS-EG) binder for Si/C600 anodes (theoretical specific capacity of 600 mAh g-1 at 0.1 C). Electrochemical testing reveals that the CCS-EG binder significantly improves the cycling stability of the Si/C anode, achieving a capacity retention rate of 88.68% after 400 cycles at a current density of 0.5 C, compared to only 67.71% for the anode using the linear carboxymethyl chitosan binder. Furthermore, CCS-EG offers advantages such as low cost, ease of preparation, and environmental sustainability, making it a promising candidate for commercialization as a binder in next-generation high-energy lithium-ion batteries.