Electrolyte Solvation and Ionic Association

Electrolytes with the salt lithium bis(fluorosulfonyl)imide (LiFSI) have been evaluated relative to comparable electrolytes with other lithium salts. Acetonitrile (AN) has been used as a model electrolyte solvent due to the simplicity of its solvation interactions (the AN molecule has only a single electron lone-pair for Li+ cation coordination). The information obtained from the thermal phase behavior, solvation/ionic association interactions, quantum chemical (QC) calculations and molecular dynamics (MD) simulations (with an APPLE&P many-body polarizable force field for the LiFSI salt) of the (AN)n-LiFSI mixtures provides detailed insight into the coordination interactions of the FSI− anions and the wide variability noted in the electrolyte transport properties (i.e., viscosity and ionic conductivity).