Supratopological Ion-Coordinated Binder Networks for Durable and Kinetically Efficient Silicon Anodes

The practical deployment of silicon (Si) anodes is limited by coupled mechanical failure and sluggish electrochemical kinetics arising from repeated volume expansion. While polymer binders are critical to electrode integrity, conventional designs often prioritize mechanical strength over ion transport. Here, a supratopological ion-coordinated binder (PVA-AA-5SAS) by integrating a hyperbranched PVA-AA framework with the sulfonated aromatic small molecule 5-sulfoisophthalic acid sodium salt (SAS) via in situ esterification is developed. The resulting 3D network effectively suppresses polymer chain slippage while simultaneously forming continuous Li⁺-coordination pathways via cooperative interactions between ester and sulfonate groups. This dual-function architecture markedly accelerates Li⁺ diffusion, reduces charge-transfer and SEI resistances, and stabilizes interfacial chemistry during deep lithiation. Si electrodes employing this binder demonstrate excellent rate capability and long-term cycling stability, maintaining a capacity retention of 79.2% after 386 cycles at 1 A in a 1 Ah‑level NCM811//SiC550 pouch cell. These results demonstrate that rational binder design can decouple and resolve the long-standing conflict between structural durability and ion conduction, providing a viable route toward kinetically efficient and mechanically durable Si-based batteries.