Chemically Coupled Multifunctional Binder Networks Enable Stable and Safe Microscale Silicon Anodes

Silicon is a promising anode material for high-energy-density lithium-ion batteries due to its ultrahigh theoretical capacity; however, its practical applications are largely impeded by severe capacity fading induced by the substantial volume changes during the lithiation and delithiation process. Here, we report a flame-retardant polymeric binder with high stretchability that significantly enhances electrochemical performance and thermal safety of microscale silicon anodes. The multifunctional binder integrates rigid poly(acrylic acid) (PAA) as a mechanically robust framework and adenosine triphosphate (ATP) as active flame-retardant segments, with the two components chemically cross-linked via amidation. The resulting µSi/ATP-PAA electrode exhibits a high initial Coulombic efficiency of 89.33% and excellent long-term cycling stability, retaining a high specific capacity of 1427 mAh g^-1 after 500 cycles at 1.2 A g^-1. Moreover, the phosphorus-rich ATP moieties significantly improve the thermal safety of silicon-based electrodes. This work provides a simple and practical strategy to design advanced binders for Si-based anodes that combine high energy density with enhanced safety for next-generation lithium-ion batteries.