A Self‐Crosslinking MOF‐Based Electrolyte Enabling Stable and Selective Li + Conduction in Solid‐State Lithium Batteries

ABSTRACT Metal–organic frameworks (MOFs), with their facile modifiability and designable nano‐confined pores, provide efficient channels for Li + transport. However, the open metal sites (OMSs) in conventional MOFs suffer from the poor stability when employed as solid‐state electrolytes, leading to compromised structural integrity and consequently, inferior long‐term cycling stability. To address this challenge, we designed an in situ polymerizable MOF‐based polymer electrolyte (PVEM) by incorporating unsaturated moieties into the MOF building blocks. The cross‐linked composite electrolyte with enhanced structural stability overcomes the bottlenecks of traditional electrolytes owning to the triply synergistic effects encompassing “confined ion transport within MOF channels”, “catalytic ion dissociation at OMSs”, and “fluorine/boron synergistic interface engineering”. Therefore, the PVEM electrolyte delivers outstanding comprehensive performance: a room‐temperature ionic conductivity of ∼0.68 mS cm − 1 and a wide electrochemical stability window up to 4.8 V. Li||Li symmetric cells demonstrate ultra‐stable cycling for over 1400 h at 0.2 mA cm − 2 with a low polarization voltage (<30 mV). This work provides a novel strategy to improve the stability of functional MOF fillers in composite electrolytes.