Multidentate Coordination Chemistry Enables Adaptive Ionic Cross-Linking of Conductive Binder for Reversible Silicon Anodes

Conductive binders present a potential solution to the volumetric instability of silicon anodes; yet their low molecular weight and limited mechanical robustness demand reversible interactions to establish stable, adaptive cross-linked networks. Building on this concept, coordination bonds with their reversible dynamics serve as a key strategy for constructing such adaptive polymer networks, though their structure–property relationships remain elusive. This work seeks to unveil the key mechanism by which ionic coordination structures govern the performance of conductive binders in silicon anodes and to establish a universal, coordination-based design strategy for ion-cross-linked binders. It is revealed that the multidentate bridge coordination between carboxylate groups and Fe 3+ simultaneously reinforces mechanical strength and maintains uniform polymer–silicon interactions, achieving the balance essential for stable cycling. Benefiting from such coordination structure, the Fe 3+ -coordinated conductive binder well accommodates silicon’s volume fluctuations, enabling reversible electrode deformation. The enhanced structural adaptability also spatially confines the growth of the solid-electrolyte interphase, preventing its thickening and the dilution of the LiF-rich phase by undesirable species. As a result, the rational binder design translates into a significant boost in the electrochemical performance of the silicon electrodes. Rooted in coordination chemistry, this work offers theoretical insights into the design of adaptive networks for high-volume-changing battery materials.