In this report, the lithium solvation behavior of two series of glyme-based electrolytes, with lithium trifluoromethanesulfonate (LiTf) or lithium-bis-(trifluormethanesulfonyl)-imide (LiTFSI) in six glymes with different chain length, is characterized using natural abundance oxygen-17 (17O) NMR spectroscopy. The effect of salt addition on chemical shift is observed by comparing the 17O NMR spectra of electrolytes and their corresponding neat solvents. The study reveals a more pronounced effect of the salt addition on the chemical shift of ether oxygens compared to terminal oxygens of glymes, thus suggesting a preferential coordination of Li+ with the ether oxygens. The 17O NMR data exhibit decreasing chemical shift changes with increasing chain length of glymes due to the increased number of ether oxygens coordinating each Li+ in the electrolytes. In addition, the trend of anion oxygen chemical shift, particularly for Tf− anion, suggests an effect of the chain length on the ion association degree. The results illustrate the sensitivity of 17O NMR to subtle changes in the ion-solvent and ion–ion interactions.

Natural Abundance Oxygen-17 NMR Investigation of Lithium Ion Solvation in Glyme-based Electrolytes

HASSOUN, Jusef;
2016

Abstract

In this report, the lithium solvation behavior of two series of glyme-based electrolytes, with lithium trifluoromethanesulfonate (LiTf) or lithium-bis-(trifluormethanesulfonyl)-imide (LiTFSI) in six glymes with different chain length, is characterized using natural abundance oxygen-17 (17O) NMR spectroscopy. The effect of salt addition on chemical shift is observed by comparing the 17O NMR spectra of electrolytes and their corresponding neat solvents. The study reveals a more pronounced effect of the salt addition on the chemical shift of ether oxygens compared to terminal oxygens of glymes, thus suggesting a preferential coordination of Li+ with the ether oxygens. The 17O NMR data exhibit decreasing chemical shift changes with increasing chain length of glymes due to the increased number of ether oxygens coordinating each Li+ in the electrolytes. In addition, the trend of anion oxygen chemical shift, particularly for Tf− anion, suggests an effect of the chain length on the ion association degree. The results illustrate the sensitivity of 17O NMR to subtle changes in the ion-solvent and ion–ion interactions.
Peng, Jing; Carbone, Lorenzo; Gobet, Mallory; Hassoun, Jusef; Devany, Matthew; Greenbaum, Steven
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2358467
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