A Spiderweb-Inspired Dual-Crosslinked Polymer Binder for Stable Silicon Anodes

Silicon (Si) anodes suffer from severe structural degradation caused by large volume variation during lithiation/delithiation, requiring binders that can simultaneously provide mechanical support and deformation adaptability. Inspired by the functional specialization of spider webs, a dual-crosslinked polymer binder (DA1-B-PA) is developed by integrating differentiated load-bearing and energy-dissipating junctions into a hierarchical network. In this design, acrylic acid segments provide strong interfacial adhesion, flexible poly(ethylene glycol) methacrylate (APEG) chains accommodate deformation and facilitate Li-ion transport, Diels–Alder linkages construct stable load-bearing frameworks, and reversible boronate ester bonds enable local structural adjustment and energy dissipation. This molecularly engineered architecture effectively balances mechanical robustness and structural flexibility. Compared with conventional poly(acrylic acid) (PAA) and non-crosslinked DA1 binders, DA1-B-PA exhibits enhanced mechanical strength, hysteretic energy dissipation, and improved electrode integrity. Consequently, Si electrodes with DA1-B-PA deliver reversible capacities of approximately 1900, 1750, and 1300 mAh g−1 after 260, 550, and 850 cycles at 0.2, 0.5, and 1 C, respectively. Moreover, the Si||LiNi0.8Co0.1Mn0.1O2 (NCM811) full cell retains 73.15% of its capacity after 311 cycles. This work demonstrates that biomimetic functional differentiation provides a rational strategy for designing durable binders for high-volume-change electrode materials.