Lithium solvation and diffusion in the 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquid

• Published in: Journal of Raman spectroscopy Vol. 39; no. 5; pp. 627 - 632
• Main Authors: Duluard, Sandrine, Grondin, Joseph, Bruneel, Jean-Luc, Pianet, Isabelle, Grélard, Axelle, Campet, Guy, Delville, Marie-Hélène, Lassègues, Jean-Claude
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.05.2008; Wiley
• Subjects: 1-butyl-3-methylimidazolium; Analytical chemistry; Anions; bis(trifluoromethanesulfonyl)imide; Cations; Chemical Sciences; Clusters; Diffusion; diffusion coefficients; ionic liquid; Ionic liquids; Lithium; Lithium ions; lithium transference number; Material chemistry; Organic chemistry; Solvation; Lithium transference number; 1-butyl-3-methylimidazolium; Bis(trifluoromethanesulfonyl)imide; Diffusion coefficients; Ionic liquid
• ISSN: 0377-0486; 1097-4555
• DOI: 10.1002/jrs.1896

The Raman spectra of (1 − x)(BMITFSI), xLiTFSI ionic liquids, where 1‐butyl‐3‐methylimidazolium cation (BMI+) and bis(trifluoromethane‐sulfonyl)imide anion (TFSI−) are analyzed for LiTFSI mole fractions x < 0.4. As expected from previous studies on similar TFSI‐based systems, most lithium ions are shown to be coordinated within [Li(TFSI)2]− anionic clusters. The variation of the self‐diffusion coefficients of the 1H, 19F, and 7Li nuclei, measured by pulsed‐gradient spin‐echo NMR (PGSE‐NMR) as a function of x, can be rationalized in terms of the weighted contribution of BMI+ cations, TFSI− ‘free’ anions, and [Li(TFSI)2]− anionic clusters. This implies a negative transference number for lithium. Copyright © 2008 John Wiley & Sons, Ltd.