Hybrid Crosslinked Solid Polymer Electrolyte via In‐Situ Solidification Enables High‐Performance Solid‐State Lithium Metal Batteries

Abstract Solid‐state lithium‐metal batteries constructed by in‐situ solidification of cyclic ether are considered to be a critical strategy for the next generation of solid‐state batteries with high energy density and safety. However, the poor thermal/electrochemical stability of linear polyethers and severe interfacial reactions limit its further development. Herein, in‐situ ring‐opening hybrid crosslinked polymerization is proposed for organic/inorganic hybrid polymer electrolyte (HCPE) with superior ionic conductivity of 2.22 × 10 −3 S cm −1 at 30 °C, ultrahigh Li + transference number of 0.88, and wide electrochemical stability window of 5.2 V. These allow highly stable lithium stripping/plating cycling for over 1000 h at 1 mA cm −2 , which also reveal a well‐defined interfacial stabilization mechanism. Thus, HCPE endows assembled solid‐state lithium‐metal batteries with excellent long‐cycle performance over 600 cycles at 2 C (25 °C) and superior capacity retention of 92.1%. More importantly, the proposed noncombustible HCPE opens up a new frontier to promote the practical application of high safety and high energy density solid‐state batteries via in‐situ solidification.