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
2012.03.25

課題番号 Project No.

装置責任者 Name of responsible person

2012B0176

Toru Ishigaki

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Relaxation analysis of electrode materials for Li-ion secondary battery

BL-20

実験責任者名 Name of principal investigator

実施日 Date of Experiment

Takeshi Yao

2012.12.11 09:00 ~ 2012.12.12 09:00

所属 Affiliation
Kyoto 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.

- Name of sample : Lithium titanate- Chemical formula : Li4/3+xTi5/3O4 (x=0 and 0.5)

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.
Li4/3Ti5/3O4 with median diameter of 20.5 m (LT-017, Ishihara Sangyo, Ltd, Japan) was used for thisexperiment. Lithium was electrochemically inserted into the Li4/3Ti5/3O4 at 25 ℃ using an Ar-sealed
three-electrode glass beaker cell. For working electrode, the Li4/3Ti5/3O4 powder was mixed with AB (AcetyleneBlack, Surface area: 133m2g-1, Denkikagaku Kogyo Corp., Ltd) as a supplemental conductor and PTFE powder
as an adhesive agent in a weight ratio of 0.7:0.3:0.05. The mixture was ground, spread and pressed onto a nickel
mesh as a current collector. Lithium metal was used for the counter and reference electrode. 1M ethylene
carbonate and a 1,2-dimethoxyethane solution (1:1, v/v) of lithium perchlorate (LiClO 4 EC/DME, Kishidachemical Corp., Ltd) was used for the electrolyte. The electrode fabrication and the cell assembly were carriedout under argon gas system. The samples were discharged from the natural potential of approximately 3 V (vs.
Li/Li+) at a current density of 1C. The amount of Li estimated by integrating the current was x= 0.50 in terms ofLi4/3+xTi5/3O4. After the required electrochemical conditions were attained, the circuits were opened immediately.
And the working electrode was detached from the glass beaker cell and set in a vanadium cell in an argon gas
system and this was used for neutron diffraction test.
12. 実験方法及び結果（つづき） Experimental method and results (continued)
Due to limitation of measuring time, we made samples with several relaxation time (10, 25, and 50 hours) after
the lithium insertion. Neutron powder diffraction was measured at room temperature for all specimens. Theobtained neutron diffraction patterns were analyzed by the Rietveld method by using N-RIEVEC program codedby T. Yao. Two phases Rietveld analysis was conducted based on Li4/3Ti5/3O4 and Li7/3Ti5/3O4. The crystal
structure of both phases was represented by the space group Fd-3m. The peaks derived from the nickel collector
observed in the patterns were evaluated as background and excluded from the analysis (Figure 1).
Figure 1 shows one example of the fitting results of the sample after the lithium insertion followed by therelaxation time of 10 h. Using the refined scale factors and lattice parameters of two phases, relative mole
fraction changes in the process of relaxation were calculated with the following equation [1].

M  S ( ZV ) /  S ( ZV )npp

pi 1ii

where MP, S, Z, and V are the relative mole
fraction of phase p in a mixture of n phases, theRietveld scale factor, the number of formula units
per unit cell and the unit cell volume, respectively.
After lithium insertion, the mole fraction ofLi4/3Ti5/3O4 phase increased and that of Li7/3Ti5/3O4
phase decreased as the increase of the relaxation
time. At the Li insertion process, it is consideredthat Li7/3Ti5/3O4 phase including lithium defects
favorable lithium diffusion formed during thelithium insertion process. On the relaxation process
after the lithium insertion, it is considered that thedefective Li7/3Ti5/3O4 phase separated to Li7/3Ti5/3O4
phase without lithium defects and Li4/3Ti5/3O4
phase.
By the neutron diffraction tests for the various
lithium insertion samples as a function of lithium
insertion rate and amount, we would like toinvestigate more about the relaxation behaviors of
Li4/3Ti5/3O4 electrode for the development of theelectrode material.
Reference[1] Roderick J. Hill, in The Rietveld Method, R. A. Young, Editor, p 95, Oxford Univ. Press, Oxford (1995).

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