Lessons From Deep Eutectic Solvents to Design High Entropy Electrolytes for Electrochemical Energy Storage

The increased interest that high-entropy electrolytes (HEEs) are lately receiving makes their design (in terms of number of different components and ratio among them) challenging. Most of current efforts to bring some light into the combinatorial design space of HEEs rely on developing machine models but it is yet necessary identifying solvent descriptors that can accurately capture key solvent properties. Thus, there is an urgent need of alternative strategies offering convenient and powerful approaches for designing HEEs. Here, we hypothesized that deviations from ideality may indeed be a fingerprint of solvent mixtures with complex and nonadditive molecular interactions between components. While little attention has been paid to the nonlinear correlations in HEEs, deviations from ideality have been largely studied in deep eutectic solvents (DESs). The aim of this perspective is to demonstrate that these deviations serve as a definitive fingerprint of the solvation architecture of not only DESs but also HEEs, allowing these thermodynamic anomalies to be used as a proxy for determining the entropic landscape of some specific HEE compositions.