A Phase‐Separated Ionogel Binder Enabling Stress‐Transport Decoupling for Durable Silicon Anodes

ABSTRACT Silicon (Si) is a promising candidate for high energy density in Li‐ion batteries beyond conventional graphite anodes, but suffers severe structural degradation and unstable interfacial evolution during cycling. This study presents a phase‐separated ionogel (PS‐IG) binder enabling stress‐transport decoupling for durable Si anodes. The binder forms a continuous network with spatially distinct polymer‐rich and ionic liquid–rich domains, allowing independent optimization of mechanical regulator and Li‐ion transport. As a result, this architecture enables efficient stress accommodation while maintaining efficient Li‐ion transport, leading to stable Si anode operation under demanding conditions. The Si anode with the PS‐IG binder delivers a reversible capacity of 703 mAh g −1 after 1000 cycles at 5.0 A g −1 , with an average coulombic efficiency above 99.2%. Moreover, a practical Si–LiFePO 4 full cell with a low N/P ratio exhibits stable cycling over 200 cycles. This study establishes that the PS‐IG architecture enables an effective binder design strategy for tailoring solutions to inherent material limitations.