A study of the Li/Li+ couple in DMC and PC solvents: Part 1: Characterization of LiAsF6/DMC and LiAsF6/PC solutions

Abstract The structures of LiAsF6/DMC and LiAsF6/PC solutions have been investigated at 300 K by infrared and Raman spectroscopies in the 4000–200 cm−1 wavenumber range using various salt concentrations. A dissociation of the lithium salt into its ionic species, Li+ and AsF6−, occurs in PC solutions. In DMC solutions, analysis of the ν3 AsF6− mode reveals the presence of contact ion-pairs Li+⋯AsF6−, free AsF6− ions, solvated ion-pairs [Li(DMC)4]+⋯AsF6−, and polymeric ion-pairs (Li+⋯AsF6−)x when the salt concentration changes from 0.1 to 4.5 mol dm−3. Moreover, we have shown that the conformational equilibrium of DMC was modified by the solvation of lithium ions strongly increasing the amount of the minor conformer.