Solvate ionic liquid-based ionogels for lithium metal batteries over a wide temperature range

Abstract

Ionogels for lithium metal batteries are usually obtained by immobilization of lithium salt-containing ionic liquids using linear polymers as gelator, which are thermally unstable and lack of adhesion. Meanwhile, the two-cation (ionic liquid cation and lithium ion) competition results in low lithium-ion transference number. In this work, we designed novel ionogels by in situ UV radiation-induced chemically crosslinked polymerization of butyl acrylate in a solvate ionic liquid ([Li(G4)][TFSI]) without additional lithium salt. The obtained ionogels (IG-m/n, m/n is the weight ratio between butyl acrylate and solvate ionic liquid) exhibit nonflammability, favorable thermal and mechanical features, high ionic conductivity, wide electrochemical window, and interestingly adhesive ability that provides an intimate contact with the Li anode. Consequently, one of the ionogels, IG-1/2, owing to its optimized adhesion, ionic conductivity, and mechanical property, could endow the as-fabricated Li|IG-1/2|LiFePO4 cells with high cyclability and Coulombic efficiency at room temperature, 90 °C, and 150 °C.