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

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• 作者：Jing Peng^a ; ^b ; Lorenzo Carbone^c ; Mallory Gobet^a ; Jusef Hassoun^d ; Matthew Devany^e ; Steven Greenbaum^a ; ^{steve.greenbaum@hunter.cuny.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Lithium battery electrolytes ; glymes ; oxygen-17 NMR ; ion solvation ; ion association
• 刊名：Electrochimica Acta
• 出版年：2016
• 出版时间：20 September 2016
• 年：2016
• 卷：213
• 期：Complete
• 页码：606-612
• 全文大小：1403 K

文摘

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.