A Rigid–Flexible Network Binder with Multiple Hydrogen Bond Interactions for High-Performance Silicon Anodes

Silicon (Si) is widely regarded as the most promising anode material for next-generation lithium-ion batteries due to its exceptionally high theoretical specific capacity. However, its practical application is severely hindered by the substantial volume changes and stresses induced during the (de)lithiation process. In this study, to enhance the stability of silicon anodes, a spiderweb-like rigid–flexible three-dimensionally cross-linked network binder, PA2X1, is developed through the in situ cross-linking of rigid poly(acrylic acid) (PAA) with flexible carboxylated acrylonitrile-butadiene rubber (XNBR). The flexible XNBR accommodates significant volume changes of Si species during (de)lithiation, while the rigid PAA serves as a structural backbone, effectively buffering mechanical stresses and preserving the mechanical integrity of the Si-based electrode throughout the cycling process. With the aid of the synergistic effect of rigidity and flexibility, the Si@PA2X1 electrode exhibits a limited thickness change of only 13.8% after 100 cycles at a current density of 0.5 A g^–1. Remarkably, it retains a high reversible capacity of 1469 mAh g^–1, with a high capacity retention of 71.7% after 300 cycles at 1000 mA g^–1, demonstrating exceptional structural integrity and cycling stability. Therefore, this rigid–flexible 3D network binder offers a promising strategy for advancing lithium-ion batteries with improved capacity and extended cycle life.