Design and Preparation of Self‐Adaptive and Robust Solid‐State Elastomeric Electrolyte for Lithium Metal Battery Inspired by Rubber Tire

The development of safe, high‐performance solid‐state electrolytes remains a central challenge for advancing lithium metal batteries (LMBs) toward practical deployment. Inspired by the durable, deformable nature of rubber tires, we report the design and preparation of a self‐adaptive solid‐state elastomeric electrolyte containing a deep eutectic electrolyte, termed PMEC, which integrates molecular‐level plasticizer dispersion, mechanical flexibility, and interfacial adaptivity. The PMEC membrane exhibits high ionic conductivity (2.37 mS cm −1 at 30 °C), a high Li⁺ transference number (0.64), excellent elasticity, and robust interfacial adhesion (36.34 J m −2 ). Structural characterizations confirm its amorphous and homogeneously mixed nature, while micro‐Raman and XPS/TOF‐SIMS analyses reveal uniform component distribution and the formation of an organic–inorganic gradient SEI layer on lithium. These features enable exceptional electrochemical performance in both symmetric and full batteries, including over 2000 h of stable cycling and >800 cycles at 0.5 C in LFP|PMEC|Li batteries with >88% capacity retention. Moreover, PMEC‐based pouch batteries maintain functionality under severe mechanical abuse. This tire‐inspired electrolyte design offers a generalizable platform for high‐safety and high‐performance solid‐state lithium batteries.