実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF Experimental Report

提出日 Date of Report
July 31, 2017

課題番号 Project No.

装置責任者 Name of responsible person

BL21 2016B0014

Toshiya Otomo

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Li+ solvation structure in glyme-Li salt molten complexes

BL 21 NOVA

実験責任者名 Name of principal investigator

実施日 Date of Experiment

Kazuhide Ueno

February 18-21, 2017

所属 Affiliation
Yokohama National University
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
[Li(G3)][OTf]; G3: triglyme, OTf: triflate, 2 different isotopes (6Li/natLi1.)
LiClO4/3SL concentrated electrolytes; ClO4: perchlorate, SL: sulfolane, 2 different isotopes (6Li/natLi)
1.0 M LiTFSA in DMF-d7 solution, TFSA: bis(trifluoromethylsulfonyl)amide, 2 different isotopes (6Li/natLi)
3.2 M LiTFSA in DMF-d7 solution, 2 different isotopes (6Li/natLi)
LiTFSA/2SL concentrated electrolytes; 2 different isotopes (6Li/natLi)
LiTFSA/4DMSO-d6 concentrated electrolytes, 2 different isotopes (6Li/natLi)

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

Experimental Method:
Cylindrical Vanadium cells with 6mm in inner diameter was used for 1H-enriched samples while the cylindricalcells with 10 mm in inner diameter was used for deuterated samples. Neutron scattering measurements wereperformed at room temperature using the NOVA spectrometer installed at BL21 of the MLF. The exposure time
was set to 4-8 h for 6Li-enriched samples whereas it was allowed to be 2-4 h for 7Li-enriched samples at thecondition of accelerator beam power of 150 kW.
Data were analyzed in a similar way as reported in our previous works. Despite large absorption cross section,
absorption correction for 6Li-enriched sample has already been confirmed to work satisfactorily with our dataanalysis program. Inelasticity contributions involved in scattering data for solvents could be cancelled out by
taking difference between observed scattering cross sections for 6Li- and 7Li-enriched samples. The first-orderdifference function, ΔLi(Q), was derived from the difference between 6Li- and 7Li-enriched samples. The
environmental distribution function around Li+ (i.e., radial distribution function of Li+) was obtained from
Fourier transform of the observed ΔLi(Q).
12. 実験方法及び結果（つづき） Experimental method and results (continued)
Results:[Li(G3)][OTf] has melting point above room temperature, but is prone to forming a supercooled liquid (i.e., itremain as liquid at room temperature for long time). However, [Li(G3)][OTf] was partially crystalized in theVanadium cell during measurements for the long exposure time, and the strong diffraction peak emerged in theobtained data unfortunately. Despite small signal-to-noise ratio, we could analyzed the ΔLi(Q) data for[Li(G3)][OTf] with 6/7Li isotopic substitution, its Fourier transform gave a strong peak at r = 2.11 Å in thedistribution function of lithium ions, GLi(r).
The much clearer results with high signal-to-noise ratio were obtained for the samples with deuterated solvents,
such as 1.0 M LiTFSA in DMF-d7 solution, 3.2 M LiTFSA in DMF-d7 solution, LiTFSA/4DMSO-d6
concentrated electrolyte. Li-O distance was reflected as a nearst neighbor peak at 1.96 Å for
LiTFSA/4DMSO-d6 concentrated electrolyte. A strong peak was observed at r = 1.93 Å corresponding to Li-O
distance for both 1.0 M and 3.2 M LiTFSA in DMF-d7 solutions, independent of the salt concentration.
Probably, Li-Li correlations corresponds to 3.00 and 2.92 Å for 1.0 M and 3.2 M LiTFSA in DMF-d7,respectively.

Fig. ΔLi(Q) (left) and GLi(r) (right) of lithium ions for 1.0 M LiTFSA in DMF-d7 and 3.2 M LiTFSA in DMF-d7
solutions.
We successfully obtained reasonable data for the other samples with protonated solvents, such as LiClO4/3SL
concentrated electrolytes, LiTFSA/2SL concentrated electrolytes. Fourier transform of the ΔLi(Q) data showed apeak at 1.91 and 1.86 Å for LiClO4/3SL concentrated electrolytes and LiTFSA/2SL concentrated electrolytes,
respectively, although these analysis needs to be optimized in more detail.
Further analysis of liquid structure of these concentrated electrolytes will be performed on molecular dynamic
simulation on the basis of the obtained distribution function of lithium ions here. This will lead to understanding
the poor solubility of lithium polysulfides species in these concentrated electrolytes, and the feedback allows us
to newly design the more appropriate liquid electrolytes for high-energy density and long-lived lithium sulfur
battery.

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