To increase the safety and stability of Lithium ion batteries, the development of electrolytes based on ionic liquids gained a lot of attention in recent years. However, with graphite electrodes neat ILs afford weak cycling performance in the absence of organic additives (e.g. vinylene carbonate, VC). The potential formation of a [Li+]-OVC interaction/coordination could have a major influence on the observed electrochemical behavior of Li-ion batteries. On a specific electrolyte, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C1C6Im][NTf2] in association with Li[NTf2] (1mol.L-1) and VC, we performed NOESY, {1H-7Li} HOESY correlations, and pulsed field gradient spin-echo NMR measurements, combined with molecular dynamics simulations in order to determine if a such interaction/coordination between VC and Li+ ions is noticeable. {7Li-1 H} HOESY experiment shows the vicinity of VC with [Li+] cation and Strong correlations and association between [Li+]and VC is observed in intense first peaks in radial distribution functions and quantified by the coordination numbers in the first solvation shell between [Li+]and the carbonyl oxygen atom of VC.

Investigation of Li+ cation Coordination and Transportation, by Molecular Modeling and NMR Studies, in a LiNTf2 doped Ionic Liquid-Vinylene Carbonate Mixture

F. Castiglione;A. Mele;
2018-01-01

Abstract

To increase the safety and stability of Lithium ion batteries, the development of electrolytes based on ionic liquids gained a lot of attention in recent years. However, with graphite electrodes neat ILs afford weak cycling performance in the absence of organic additives (e.g. vinylene carbonate, VC). The potential formation of a [Li+]-OVC interaction/coordination could have a major influence on the observed electrochemical behavior of Li-ion batteries. On a specific electrolyte, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C1C6Im][NTf2] in association with Li[NTf2] (1mol.L-1) and VC, we performed NOESY, {1H-7Li} HOESY correlations, and pulsed field gradient spin-echo NMR measurements, combined with molecular dynamics simulations in order to determine if a such interaction/coordination between VC and Li+ ions is noticeable. {7Li-1 H} HOESY experiment shows the vicinity of VC with [Li+] cation and Strong correlations and association between [Li+]and VC is observed in intense first peaks in radial distribution functions and quantified by the coordination numbers in the first solvation shell between [Li+]and the carbonyl oxygen atom of VC.
2018
ionic liquids, electrolyte, lithium, diffusion coefficient, solvation, NMR, molecular simulation
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1063469
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