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 N. Canongia Lopes, Rob Atkin, Kazuhide Ueno, Kaoru Dokko, Masayoshi Watanabe, Yasuo Kameda, Yasuhiro Umebayashi

    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
    StatePublished - 2016 Jul 21

    Fingerprint

    Ionic liquids
    Solvation
    Neutrons
    Lithium
    Substitution reactions
    Positive ions
    Scattering
    Experiments
    Amides
    Distribution functions
    Ethylene
    Negative ions
    Sulfur
    Electrolytes
    Atoms
    Molecules
    Oxides
    Oxygen
    Temperature

    ASJC Scopus subject areas

    • Materials Science(all)

    Cite this

    Li+ Local Structure in Li-Tetraglyme Solvate Ionic Liquid Revealed by Neutron Total Scattering Experiments with the 6/7Li Isotopic Substitution Technique. / Saito, Soshi; Watanabe, Hikari; Hayashi, Yutaka; Matsugami, Masaru; Tsuzuki, Seiji; Seki, Shiro; Canongia Lopes, José N.; Atkin, Rob; Ueno, Kazuhide; Dokko, Kaoru; Watanabe, Masayoshi; Kameda, Yasuo; Umebayashi, Yasuhiro.

    In: Journal of Physical Chemistry Letters, Vol. 7, No. 14, 21.07.2016, p. 2832-2837.

    Research output: Contribution to journalArticle

    Saito, S, Watanabe, H, Hayashi, Y, Matsugami, M, Tsuzuki, S, Seki, S, Canongia Lopes, JN, Atkin, R, Ueno, K, Dokko, K, Watanabe, M, Kameda, Y & Umebayashi, Y 2016, 'Li+ Local Structure in Li-Tetraglyme Solvate Ionic Liquid Revealed by Neutron Total Scattering Experiments with the 6/7Li Isotopic Substitution Technique' Journal of Physical Chemistry Letters, vol 7, no. 14, pp. 2832-2837. DOI: 10.1021/acs.jpclett.6b01266

    Saito, Soshi; Watanabe, Hikari; Hayashi, Yutaka; Matsugami, Masaru; Tsuzuki, Seiji; Seki, Shiro; Canongia Lopes, José N.; Atkin, Rob; Ueno, Kazuhide; Dokko, Kaoru; Watanabe, Masayoshi; Kameda, Yasuo; Umebayashi, Yasuhiro / Li+ Local Structure in Li-Tetraglyme Solvate Ionic Liquid Revealed by Neutron Total Scattering Experiments with the 6/7Li Isotopic Substitution Technique.

    In: Journal of Physical Chemistry Letters, Vol. 7, No. 14, 21.07.2016, p. 2832-2837.

    Research output: Contribution to journalArticle

    @article{ea6ecb0eba2a4dc5b390832cbfb26ff2,
    title = "Li+ Local Structure in Li-Tetraglyme Solvate Ionic Liquid Revealed by Neutron Total Scattering Experiments with the 6/7Li Isotopic Substitution Technique",
    author = "Soshi Saito and Hikari Watanabe and Yutaka Hayashi and Masaru Matsugami and Seiji Tsuzuki and Shiro Seki and {Canongia Lopes}, {José N.} and Rob Atkin and Kazuhide Ueno and Kaoru Dokko and Masayoshi Watanabe and Yasuo Kameda and Yasuhiro Umebayashi",
    year = "2016",
    month = "7",
    doi = "10.1021/acs.jpclett.6b01266",
    volume = "7",
    pages = "2832--2837",
    journal = "Journal of Physical Chemistry Letters",
    issn = "1948-7185",
    publisher = "American Chemical Society",
    number = "14",

    }

    TY - JOUR

    T1 - Li+ Local Structure in Li-Tetraglyme Solvate Ionic Liquid Revealed by Neutron Total Scattering Experiments with the 6/7Li Isotopic Substitution Technique

    AU - Saito,Soshi

    AU - Watanabe,Hikari

    AU - Hayashi,Yutaka

    AU - Matsugami,Masaru

    AU - Tsuzuki,Seiji

    AU - Seki,Shiro

    AU - Canongia Lopes,José N.

    AU - Atkin,Rob

    AU - Ueno,Kazuhide

    AU - Dokko,Kaoru

    AU - Watanabe,Masayoshi

    AU - Kameda,Yasuo

    AU - Umebayashi,Yasuhiro

    PY - 2016/7/21

    Y1 - 2016/7/21

    N2 - 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.

    AB - 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.

    UR - http://www.scopus.com/inward/record.url?scp=84979620530&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=84979620530&partnerID=8YFLogxK

    U2 - 10.1021/acs.jpclett.6b01266

    DO - 10.1021/acs.jpclett.6b01266

    M3 - Article

    VL - 7

    SP - 2832

    EP - 2837

    JO - Journal of Physical Chemistry Letters

    T2 - Journal of Physical Chemistry Letters

    JF - Journal of Physical Chemistry Letters

    SN - 1948-7185

    IS - 14

    ER -