Li+ Local Structure in Li-Tetraglyme Solvate Ionic Liquid Revealed by Neutron Total Scattering Experiments with the 6/7Li Isotopic Substitution Technique

Soshi Saito, Hikari Watanabe, Yutaka Hayashi, Masaru Matsugami, Seiji Tsuzuki, Shiro Seki, José Nuno Aguiar Canongia Lopes, Rob Atkin, Kazuhide Ueno, Kaoru Dokko, Masayoshi Watanabe, Yasuo Kameda, Yasuhiro Umebayashi

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Equimolar mixtures of lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) and tetraglyme (G4: CH3O-(CH2CH2O)4-CH3) yield the solvate (or chelate) ionic liquid [Li(G4)][TFSA], which is a homogeneous transparent solution at room temperature. Solvate ionic liquids (SILs) are currently attracting increasing research interest, especially as new electrolytes for Li-sulfur batteries. Here, we performed neutron total scattering experiments with 6/7Li isotopic substitution to reveal the Li+ solvation/local structure in [Li(G4)][TFSA] SILs. The experimental interference function and radial distribution function around Li+ agree well with predictions from ab initio calculations and MD simulations. The model solvation/local structure was optimized with nonlinear least-squares analysis to yield structural parameters. The refined Li+ solvation/local structure in the [Li(G4)][TFSA] SIL shows that lithium cations are not coordinated to all five oxygen atoms of the G4 molecule (deficient five-coordination) but only to four of them (actual four-coordination). The solvate cation is thus considerably distorted, which can be ascribed to the limited phase space of the ethylene oxide chain and competition for coordination sites from the TFSA anion.

Original languageEnglish
Pages (from-to)2832-2837
Number of pages6
JournalJOURNAL OF PHYSICAL CHEMISTRY LETTERS
Volume7
Issue number14
DOIs
Publication statusPublished - 21 Jul 2016

Fingerprint Dive into the research topics of 'Li<sup>+</sup> Local Structure in Li-Tetraglyme Solvate Ionic Liquid Revealed by Neutron Total Scattering Experiments with the <sup>6/7</sup>Li Isotopic Substitution Technique'. Together they form a unique fingerprint.

Cite this