Dual-Dynamic Biomimetic Binder for High-Performance Silicon Anodes

Silicon (Si) has received widespread attention in recent years due to its high theoretical specific capacity (4200 mAh g^-1) and low deembedded lithium potential, making it a highly promising anode material. However, Si materials undergo significant volume expansion after multiple cycles, leading to rapid capacity decay in practical applications. In this study, a dynamically dual-cross-linked biomimetic binder (CMCS/PA@Fe) was developed by forming a coordination compound between protocatechuic aldehyde (PA) and Fe³⁺ and then combining it with carboxymethyl chitosan (CMCS). Inspired by the adhesive mechanism of mussels, the catechol structure in PA can provide strong adhesion, and Fe³⁺ introduced through coordination increases the ionic conductivity of the composite material. In addition, the dual-dynamically reversible chemical bonds in the CMCS/PA@Fe binder, namely, Schiff base bonds and coordination bonds, form a dual-buffering mechanism, which effectively suppressed the volume expansion of the Si anode during cycling, relieved the stress inside the electrode, and induced the generation of a stabile solid electrolyte interface layer, thereby resulting in excellent electrochemical performance. After 500 cycles at a high current rate of 4 A g^-1, the electrode capacity can still maintain 1184.9 mAh g^-1, showing that CMCS/PA@Fe is a strong candidate for next-generation Si anode binders.