Design of Localized\nHigh-Concentration Electrolytes\nfrom the Perspective of Physicochemical Properties

The physicochemical properties of electrolytes profoundly\nimpact\nthe energy density, rate performance, and manufacturability of rechargeable\nlithium batteries. Localized high-concentration electrolytes (LHCEs),\na novel electrolyte class, have attracted considerable interest, yet\nthe impact of diluents on their physicochemical properties remains\nunclear, as most reports involve only a few samples. Here we prepared\n345 electrolyte samples using 21 diluents and systematically investigated\nthe effect of diluent type and content on the miscibility, density,\nviscosity, and ion conductivity of LHCEs. We found that the physicochemical\nproperties of LHCEs are mainly affected by the diluents’ density\nand viscosity, regardless of type. Notably, the ionic conductivity\nexhibits two typical variance trends, “volcano” and\n“descending,” both correlating strongly with diluents’\nviscosity rather than dielectric constant, a parameter commonly employed\nin electrolyte design. This anomaly can be explained by the “plum\npudding” solvation model, providing essential insights for\ndeveloping lightweight, highly fluid, and conductive LHCEs.