Defect-Engineered MOF for Wide-Temperature Quasi-Solid-State Electrolyte with High Comprehensive Electrochemical Performance

Defect engineering of metal-organic framework-based electrolytes to expose abundant active sites is an effective strategy to optimize the electrochemical performance of lithium metal batteries. Herein, a three-dimensional (3D) cluster-based framework (Ni-MOF(II), ({[H₂N(CH₃)₂]₂[Ni₃(μ₃-O)(XN)(BPDC)₃]·12DMF}n)) has been harvested, and a ligand defect strategy was further employed to form three defective Ni-MOF(II)-X (X = 30, 50, 70) materials. The generation of open metal sites may provide favorable conditions for the dissociation of lithium salt and the immobilization of anions, thereby enabling efficient single-ion conduction. In electrochemical performance investigations, Ni-MOF(II)-50 presents outstanding ionic conductivity, high Li⁺ transference number and broad electrochemical stability window over a wide temperature range (1.25 × 10⁻³ S cm⁻¹, 0.83, 5.1 V at 25 °C; 1.08 × 10⁻⁴ S cm⁻¹, 0.74, 5.0 V at -30 °C). Moreover, the Li|Ni-MOF(II)-50|Li symmetric cell demonstrated stable cycling over 800 h at 0.5 mA cm⁻². This work provides a rational defect-engineering pathway for designing high-performance MOF-based quasi-solid-state electrolytes with a wide operational temperature range.