In‐Situ Functional Crosslinking Enables Facile Construction of Rigid Poly(Ethylene Oxide) Network for High Performance All‐Solid‐State Batteries

ABSTRACT Poly(ethylene oxide) (PEO) based electrolytes have garnered considerable attention in all‐solid‐state lithium metal batteries with superior safety and energy density, but suffer from low‐ion conductivity and poor cycling stability. Herein, a novel in‐situ functional crosslinking strategy is proposed to overcome these limitations simultaneously, where a two‐in‐one bis‐diazirine molecule (C1) is not only used as a rigid cross‐linker, but also functions as an electron‐withdrawing inducer. Benefitting from such an integration of two functionalities into one cross‐linker, a rigid PEO electrolyte network can be facilely constructed, while exhibiting disrupted crystallization, robust mechanical strength, loosened Li─O binding to boost the Li + transport, and anion‐rich Li + coordinated structure to favor the generation of a stable LiF‐rich solid electrolyte interface. As a result, a remarkable ion conductivity of 1.4 × 10 −3 S cm −1 is achieved at 60°C together with a Li + transference number of 0.63. And the corresponding LiFePO 4 ||Li and NCM811||Li filled batteries present significantly improved rate performance and capacity retention cycling life compared with the pristine PEO electrolyte, highlighting the great potential of in‐situ functional crosslinking for high performance all‐solid‐state batteries.