Metal‐Organic Framework Confined Solvent Ionic Liquid Enables Long Cycling Life Quasi‐Solid‐State Lithium Battery in Wide Temperature Range

Solid-state Li batteries are receiving increasing attention as a prospective energy storage system due to the high energy density and improved safety. However, the high interfacial resistance between solid-state electrolyte and electrode results in sluggish Li+ transport kinetics. To tackle the interfacial problem and prolong the cycle life of solid-state Li batteries, a quasi-solid-state electrolyte (QSSE) based on a solvate ionic liquid (SIL) space-restricted in nanocages of UIO-66 (SIL/UIO-66) is prepared in this study. Benefiting from the effective spatial confinement of the TFSI- by the pore UIO-66 and the strong chemical interactions between the SIL and metal atoms, SIL/UIO-66 QSSE exhibits high ionic conductivity and good compatibility with electrodes. As a result, Li|QSSE|LFP cells demonstrate excellent rate capability and cycle stability in a wide temperature range of 25-90 °C. This study provides a realistic strategy for the fabrication of safe solid electrolytes with excellent compatibility and long cycle life for high-performance QSSE Li-ion batteries.