MOF‐Ionic Liquid Structured Polymer Electrolytes with Multi‐Channel Ion Transport Pathways for Wide‐Temperature Solid‐State Lithium Batteries

Abstract

Abstract Composite polymer electrolytes (CPEs) enhanced with ionic liquids (ILs) are promising candidates for next‐generation solid‐state lithium metal batteries, offering advantages in interfacial compatibility and processability. However, their application across a broad temperature range has been hindered by a fundamental trade‐off between mechanical robustness and ionic conductivity. To overcome this limitation, the study designs an innovative poly(ethylene oxide) (PEO)‐based CPE architecture to decouple these properties. This architecture utilizes amino‐functionalized metal‐organic framework (MOF) nanoparticles to encapsulate and immobilize ILs within PEO‐filled electrospun membranes, establishing stable multi‐channel ion pathways across wide temperatures. Combined experimental and computational studies reveal that the functionalized MOF enables fast Li⁺ hopping at interfaces, and the MOF‐confined IL boosts bulk ion transport. This multi‐path mechanism ensures high Li⁺ conductivity and structural stability from −10 to 120 °C. Furthermore, the optimized CPE facilitates the formation of a LiF‐enriched solid electrolyte interphase and an inorganic‐dominated cathode electrolyte interphase, significantly enhancing interfacial stability. Consequently, LiFePO 4 ||Li cells exhibit excellent cyclability, retaining 96.8% capacity after 1000 cycles at 3 C, and demonstrate stable operation for over 400 cycles at both −10 and 120 °C. These results establish a novel strategy for decoupling the intrinsic compromise between mechanical and electrochemical performance in CPEs.