Dynamic-covalent three-dimensional binder-network engineering enables high-performance Si anodes with enhanced cycling stability

The severe volume expansion (~300%) of silicon (Si) anodes during cycling causes structural deterioration and rapid capacity loss, thereby limiting their practical application. Designing effective polymer binders is therefore crucial for addressing this challenge. Commonly used binders, such as PAA and CMC-SBR, mainly rely on physical entanglement or reversible hydrogen bonding and thus lack sufficient mechanical strength and adhesion to accommodate the large volume changes of Si and maintain long-term electrode stability. In this study, we designed a dynamic-covalent three-dimensional binder network, denoted DAH-c-IDA, to improve the cycling stability of Si anodes. The binder was prepared by grafting adhesive dopamine (DA) onto the biopolymer hyaluronic acid (HA), followed by covalent cross-linking with iminodiacetic acid (IDA). This design combines a robust covalent ester network with abundant dynamic supramolecular interactions. The covalent framework provides the mechanical strength required to confine Si particles, whereas the reversible dynamic bonds dissipate cyclic stress and reduce irreversible damage to the electrode architecture. By optimizing the degree of cross-linking, an appropriate balance between structural stability and adhesive flexibility was achieved at a DAH:IDA mass ratio of 2:1, giving the binder a high Young's modulus, damage tolerance, and strong interfacial adhesion. Consequently, the Si electrode fabricated with the optimized DAH-c-IDA binder achieved an initial coulombic efficiency of 94.39% and delivered a high reversible capacity of 1637 mAh g −1 after 580 cycles at a high current density of 2 A g −1 , while maintaining cycling operation for 800 cycles. This work demonstrates that integrating covalent cross-linking with dynamic supramolecular interactions within a 3D network is an effective strategy for developing advanced binders for durable, high-capacity Si-based lithium-ion batteries.