Strongly and Weakly Solvating Solvents Co-Coordinated Electrolyte for Stable Lithium Metal Batteries

Abstract

Anion-reinforced and weakly solvating electrolytes aim to optimize the composition of the primary solvation sheath by increasing anion participation, thus promoting the formation of a low-resistance solid electrolyte interphase or reducing the desolvation energy barrier of lithium ions (Li⁺). However, high salt concentrations or weakly solvating solvents can inhibit the dissociation of Li salts, resulting in impaired ionic conductivity. Here, we propose an anion-reinforced electrolyte featuring the co-coordination of strongly and weakly solvating solvents, where the weakly solvating solvent promotes anion participation in the solvation structure while the strongly solvating solvent enhances the dissociation of Li salts, thereby improving the ionic conductivity of the electrolyte. Notably, the competitive coordination between the two solvents results in a looser solvation structure, which reduces the desolvation energy of Li⁺. Ultimately, a Li metal battery with cycling stability, fast charging, and low-temperature tolerance is achieved. This study provides new insights into electrolyte design for Li metal batteries.