Making an Ultra “Strong–Tough” Interphase by a Dynamic Elastomer in All-Solid-State Lithium Metal Batteries

All-solid-state lithium metal batteries offer high energy density and enhanced safety, yet stable cycling remains difficult due to the incompatibility among inorganic phases such as solid electrolyte particles and lithium metal. Here, we address this issue by chemical grafting inorganic components with a dynamic elastomer, achieving an ultrastrong–tough maximum tensile strain of 925%. This strategy replaces weak physical contacts between inorganic phases with Si–O–Li covalent linkages to strengthen structural integrity, while dynamic hydrogen-bond reconstruction ensures high interfacial compatibility. Benefiting from this mechanism, Li⁺ transfer tortuosity is reduced and the ionic conductivity reaches 4.0 × 10^–3 S cm^–1. As a result, symmetric cells exhibit stable cycles that exceed 3000 h at 1.0 mA cm^–2. Further, the full cell and fabricated pouch cell exhibit wide temperature adaptability (−40 to 80 °C) and high plasticity, respectively. This research provides a general solution for all-solid-state batteries to address the incompatibility among inorganic phases.