A multifunctional self-healing binder with strong interfacial interactions and structural stability for...

Silicon (Si) is a promising anode material for high-energy-density lithium-ion batteries (LIBs); however, its severe volume expansion during repeated cycling induces particle pulverization and the loss of electrical contact, leading to rapid capacity degradation. To address these challenges, we propose a multifunctional self-healing polymer binder, poly(acrylic acid)-4-aminophenyl disulfide (PAA-APDS), designed to enhance interfacial adhesion and structural stability of Si anodes. The PAA-APDS binder effectively dissipates mechanical stress arising from volume changes through its three-dimensional (3D) network composed of multiple hydrogen bonds and dynamic disulfide bonds. Notably, it provides superior adhesion strength (6.5 N) via strong Cu-S interfacial bonding with the Cu current collector and spontaneously repairs microcracks owing to its intrinsic self-healing properties. As a result, the Si/PAA-APDS electrode exhibits an excellent capacity retention of 94.91% after 300 cycles while maintaining a robust electrode structure. Simultaneously, the optimized binder structure facilitates lithium-ion transport, yielding a 2.1-fold increase in the Li⁺ diffusion coefficient (D_Li⁺) compared to pristine PAA and improving the rate capability. Furthermore, a pouch full-cell configuration (NCM622||SiO_x@C/PAA-APDS20) maintained a capacity of 10 mAh after 50 cycles, demonstrating the practical applicability of this binder for Si-based high-energy density LIBs.