Hierarchical mesh-interpenetrating PEGDE-LC composite solid electrolyte for high-performance lithium metal batteries

Solid-state electrolytes face significant challenges in concurrently optimizing mechanical strength and ionic conductivity. To address this issue, a two-step synthesis strategy was employed to construct a hierarchical mesh-interpenetrating network composite electrolyte. The electrolyte contained self-crosslinking networks formed by the reaction of epoxy resin polyethylene glycol diglycidyl ether (PEGDE) catalyzed by lithium difluoro(oxalato)borate (LiDFOB), embedded within a rigid layered skeleton induced by 365 nm ultraviolet light in the liquid crystal compound 1,4-bis[4-(6-acryloyloxyhexanoyloxy)benzoyloxy]-2-methylbenzene (C6M). The independent formation and spatial interpenetration of the two network systems resulted in significant synergistic effects. The resulting PEGDE-LC composite electrolyte (designated as PLE) exhibited a room-temperature ionic conductivity of 2.61 × 10 −4  S·cm −1 , an electrochemical stability window of 4.79  V vs. Li + /Li, and a tensile strength of 4.7 MPa for the optimized PLE-3 formulation. The LFP/Li battery delivered an initial discharge capacity of 153.8 mAh·g −1 at room temperature under a 1C rate, with a capacity retention of 89.6 % (137.9 mAh·g -1) after 300 cycles. This interpenetrating network structure, based on material composite synergy, provides a novel material design strategy to overcome the trade-off between mechanical and electrochemical properties in solid-state electrolytes.