Bio-inspired rigid helical network for silicon anode binders enabled by metal-ion-mediated conformation regulation

Silicon anodes undergo severe volume changes during lithiation/delithiation, causing electrode cracking and rapid capacity fading. Although metal-ion-coordinated polysaccharide binders form crosslinked networks that mitigate silicon expansion, their potential to regulate polymer chain conformation and enhance binder mechanics remains largely unexplored. Herein, we propose a bio-inspired strategy in which metal ions mediate conformational contraction of xanthan gum (XG) chains, converting their native "millipede-like" helices into rigid rod-like segments that densely entangle into a three-dimensional "millipede-colony" network. Low-temperature pyrolysis is subsequently employed to solidify this architecture. The resulting network, composed of tightly interwoven rigid helical chains, provides strong mechanical confinement, effectively suppressing the volume expansion of silicon and preserving the stability of the electrode framework. Density functional theory, molecular dynamics simulations, and multiscale characterization reveal that a 1 % CaCl₂/XG mass ratio is the optimal regulation level for constructing the XG-based binder network. The optimized binder delivers a specific capacity of 1885.8 mAh g^-1 after 300 cycles, demonstrating remarkable cycling stability. This work demonstrates regulation of molecular chain conformation as a versatile and scalable route for enhancing binder performance in silicon-based anodes for lithium-ion batteries and potentially in other polysaccharide-based functional materials.