実験報告書様式（一般利用課題・成果公開利用）

MLF	 Experimental Report

提出日 Date of Report

課題番号 Project No.

装置責任者 Name of responsible person

2012A0212

Toshiya Otomo

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Structural analysis of nano-sized transitional-metal oxide

NOVA (BL21)

as negative electrode materials for Li-ion batteries

実施日 Date of Experiment

実験責任者名 Name of principal investigator

2013/3/22-24

Yohei ONODERA
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.
Nano-sized cobalt oxide, CoO
Mechanical alloyed LixCoO (x=0.5, 1.0, 1.5, 2.0, 2.5)

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.

In this proposal, we carried out neutron total scattering experiments in order to study the local structure ofnano-sized Li-CoO conversion negative electrode materials, which is known as promising high-capacity	 
and high-reversibility negative electrode materials for Li-ion batteries.
The LixCoO samples were synthesized by the mechanical alloying (MA) method from Li metal foil andnano-sized cobalt oxide powder.

The starting materials were put into a SUS pot with 20 SUS balls under highpurity argon gas atmosphere, and then alloyed mechanically at 100 rpm for 10 h using a planetary ball millapparatus (Fritsch, P-5).
The neutron total scattering experiments were carried out with the High Intensity Total Diffractometer(NOVA), installed at BL21 of MLF in J-PARC.

The powder samples by MA LixCoO (x=0.5, 1.0, 1.5, 2.0, 2.5),and CoO nano-sized powder were put into cylindrical vanadium-nickel cells (6 mm in diameter) under argon gas
atmosphere.

The neutron total scattering data of the samples were measured for 6 h at room temperature with

300 kW of MLF beam power. Structure factors, S(Q), were obtained from the scattering intensity after correctionof the background, attenuation, and multiple scattering and normalization with scattering from a vanadium rod.
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2. 実験方法及び結果（つづき） Experimental method and results (continued)

65
nano-sized CoO
Li1.0CoO MA sample

4g(r)

32
10-1-2
234

56r/Å
Fig.1 Pair distribution functions, g(r) for LixCoO (x=0, 1.0) samples.
Figure 1 shows pair distribution functions, g(r), obtained by the Fourier transformation of S(Q)s for LixCoO(x=0, 1.0) samples with Q range from 0.4 to 35 Å-1.

A peak was observed around at 1.9 Å in g(r) for thenano-sized CoO sample and it was attributed to Co-O nearest-neighbor correlation.

Co-O correlation peak wasvanished and a characteristic negative peak was observed at around 1.8-1.9 Å in g(r) for the Li1.0CoO sample.
This negative correlation was attributed to Li-O correlation.

Additionally, sharp positive peaks, correspond toCo-Co correlation in metallic Co, also were emerged at around 2.2 Å and 2.45 Å in g(r) for the Li1.0CoO sample.
These results suggest that the conversion reaction was occurred on MA treatment as follows.

CoO + 2Li ⇆ Li2O + Co
In the future, we will perform the detailed analysis for Co-O, Li-O, and Co-Co correlation by combination withhigh-energy X-ray diffraction data, and elucidate a relation between the structure and remarkable electrodeproperties on conversion reaction.

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