Lithium solvation in bis(trifluoromethanesulfonyl)imide-based ionic liquids

Abstract

The lithium solvation in (1 − x)(EMI-TFSI), xLiTFSI ionic liquids where EMI⁺ is the 1-ethyl-3-methylimidazolium cation and TFSI⁻ the bis(trifluoromethanesulfonyl)imide anion, is shown by Raman spectroscopy to involve essentially [Li(TFSI)₂]⁻ anionic clusters for 0 < x < 0.4, but addition of stoichiometric amounts of solvents S such as oligoethers changes the lithium solvation into [Li(S)_m]⁺ cationic clusters; the lithium transference number in TFSI-based ionic liquid electrolytes for lithium batteries should thus be strongly improved.