Design of a Multifunctional Self-Healing Polymer Binder Based on Dynamic Disulfide Crosslinking for Silicon Anodes

Polymer binders play a critical role in maintaining the structural integrity of silicon anodes that undergo severe volume expansion during repeated lithiation and delithiation. In this study, a self-healing polymer binder was prepared by chemically crosslinking a poly(acrylic acid)-based polymer through amide bond formation. The resulting polymer network incorporates dynamic disulfide bonds together with multiple hydrogen-bonding interactions, improving mechanical robustness, interfacial adhesion, and structural stability. The reversible disulfide bonds dissipate mechanical stress generated during repeated volume changes and enable autonomous repair of microcracks, while sulfur-containing functional groups promote strong interfacial bonding with the copper current collector. As a result, the optimized binder exhibited a peel strength of 6.5 N, excellent mechanical flexibility, and improved resistance to electrode delamination compared with the uncrosslinked polymer. In addition, the crosslinked network facilitated lithium-ion transport, leading to an approximately 2.1-fold increase in the Li-ion diffusion coefficient and excellent cycling stability with a capacity retention of 94.91% after 300 cycles. Stable electrochemical performance was further demonstrated in both SiOx@C half-cells and NCM622||SiOx@C pouch full cells, supporting the practical applicability of the proposed binder design. These results demonstrate that combining dynamic disulfide chemistry with multiple hydrogen-bonding interactions provides an effective strategy for designing mechanically robust polymer binders with enhanced interfacial stability for high-capacity silicon anodes.