Correlating the Solvating Power of Solvents with the Strength of Ion-Dipole Interaction in Electrolytes of Lithium-ion Batteries.

Abstract

The solvation structure of Li+ plays a significant role in determining the physicochemical properties of electrolytes. However, to date, there is still no clear definition of the solvating power of different electrolyte solvents, and even the solvents that preferentially participate in the solvation structure remain controversial. In this study, we comprehensively discuss the solvating power and solvation process of Li+ ions using both experimental characterizations and computational calculations. Our findings reveal that the solvating power is dependent on the strength of the Li+-solvent (ion-dipole) interaction. Additionally, we uncover that anions tend to enter the solvation sheath in most electrolyte systems through Li+-anion (ion-ion) interaction, which is weakened by the shielding effect of solvents. The competition between the Li+-solvent and Li+-anion interactions ultimately determines the final solvation structures. This insight into the fundamental understanding of the solvation structure of Li+ ions provides inspiration for the design of multifunctional mixed-solvent electrolytes for advanced batteries.