(298h) Simulation Guided Molecular Design of Hydrofluoroether Solvent for High Energy Batteries

Efficient electrolyte design is paramount in advancing next-generation batteries with enhanced energy densities. Hydrofluoroether (HFE) solvents have garnered significant interest due to their potential to offer desirable properties, including high oxidative stability, ionic conductivity, and improved compatibility with lithium metal. Nonetheless, understanding the intricate solvation-property relationships and design principles for high-performance HFE solvents still needs to be improved. This study presents four novel asymmetric HFE designs, systematically varying polyether and fluorocarbon structural building blocks. By leveraging molecular dynamics (MD) modeling to analyze the solvation structures and predict the properties of the corresponding 1 M lithium bis(fluorosulfonyl)imide (LiTFSI) solutions, we downselected the most promising candidate based on solubility, conductivity, and oxidative stability for extensive electrochemical characterizations. The formulated electrolyte exhibits properties consistent with simulation predictions and demonstrates significantly improved capacity retention compared to baseline electrolytes when cycled in lithium metal cells. This research showcases the construction of candidate electrolytes from building block functional moieties to engineer fundamental solvation structures, facilitating the discovery and rational design of novel solvent materials.