High Correlation Between Li Solvation Energy and Li Ionic Conductivity in Lithium Metal Battery Electrolytes.

In lithium metal batteries, accurately estimating the Li solvation ability of solvents is essential for effectively modulating the Li solvation sheath to form a stable interphase and achieve high ionic conductivity. However, previous studies have shown that the theoretically calculated Li binding energy, commonly used to evaluate solvation ability, exhibits only a moderate correlation with experimentally measured ionic conductivity (R = 0.68). In this study, to determine the effective theoretical descriptor for evaluating the solvation ability, Li solvation energy was adopted instead of Li binding energy, and its correlation with ionic conductivity was compared. Using a sophisticated calculation model that considers the Li counter anion and solvent, it was demonstrated that the tendency between the calculated Li solvation energies and experimentally measured ionic conductivities is highly consistent (R = 0.97). Therefore, Li solvation energy is suggested as the theoretical descriptor for evaluating solvation ability. All these findings encourage the development of effective molecular design of solvents for lithium metal batteries.