実験報告書様式（一般利用課題・成果公開利用）

MLF Experimental Report
課題番号 Project No. 2009A0031

提出日 Date of Report
January 06, 2010
装置責任者 Name of responsible person
Yasuhiro Miyake

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Lithium diffusion in lithium-transition-metal-oxides

D1

実験責任者名 Name of principal investigator

実施日 Date of Experiment

Jun Sugiyama

June 10, 2009 ‒ June 13, 2009

所属 Affiliation
Toyota Central Research and Development Laboratories, Inc.
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.

Lithium nickel dioxides, Li1-xNi1+xO2 with x~0.07.
A powder sample was pressed in a disc with 30 mm diameter and 2 mm thickness, and then thedisc was packed in an Au-sealed cell.

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 order to detect the diffusion coefficient of Li+ ions (DLi) in LiNiO2, which are heavily
investigated as a cathode material for the next-generation Li-ion batteries, we have measured
wTF-, ZF-, and LF-µSR spectra for LiNiO2 in the temperature range between 60 and 450 K. Here,it should be noted that, in the rhombohedral LiNiO2 lattice with space group R3-m, the NiO2 plane
and the Li layers form alternating stacks along the cH-axis in the hexagonal setting (see Fig. 1). In
the NiO2 planes, Ni ions form a two-dimensional triangular lattice (2DTL) by a network ofedge-sharing NiO6 octahedra. In contrast to LiCoO2, a stoichiometric LiNiO2 has never been
prepared so far. That is, the excess Ni is usually present in the Li layer of the LiNiO2 samples dueto the similarity in ionic radii between Li+ and Ni3+. The ionic distribution of the Ni-excess LiNiO2
is thus given by (Li+1-xNi2+x)3b[Ni2+xNi3+1-x]3aO2, where 3b and 3a are the Li and Ni site in theregular LiNiO2 lattice. Besides of an interesting change in low-T magnetism of Li1-xNi1+xO2 with x,the (Ni2+)3b ions are naturally expected to affect DLi at high T, because of planer hindrance of(Ni2+)3b in the Li layer, in which Li+ ions move relatively easily. Nevertheless, there is, to authors'.

12. 実験方法及び結果（つづき） Experimental method and results (continued)" (106 s-1)

! (106 s-1)

knowledge, less systematic work on the relationship between DLi and x, mainly due to lack of aproper tool for detecting DLi. The µSR experiment on Li1-xNi1+xO2 with x~0.03, ~0.07, and ~0.15,
therefore, provides crucial information on the effect on DLi, resulting in clear insight how toimprove cathode materials.
Following upon the experiment on the x~0.03 and~0.15 samples in February of 2009, we attempted tomeasure µSR spectra for the x~0.07 sample, which wasprepared by heating the x~0.03 sample at 850oC. The ZFand LF-spectra were well fitted by a dynamic
Kubo-Toyabe function, as in the case for the previous twosamples. By using a global fit technique for ZF-, LF-, andwTF-spectra, the field distribution width (Δ) and field
fluctuation rate (ν) for the x~0.07 sample were estimatedat each temperature (red circles in Fig. 2). Surprisingly, νof the x~0.07 sample is found to be almost T-independent Fig.1 The crystal structure ofup to the highest T measured (450oC), although Δ LiNiO2.
decreases with T as observed for the other two samples.
Based on the previous results, ν for the x~0.03 and1 LiNiO2o~0.15 samples increased with T, as expected. Also, the750 Co
increase in ν with T for the x~0.15 sample was suppressed
950 C0.5o850 C
compared with that for the x~0.03 sample, being consistent
with the planer hindrance of the Ni ions in the Li layer.
Therefore, it is very difficult to explain the ν(T) curve for0the x~0.07 sample, although ν would exhibit a complex
0.5
dependence on x. In order to confirm the result on the0.4
x~0.07 sample and to add T points for the x~0.15 sample,
0.3
we plan to continue the experiment in the winter of0.2
2009/2010.
0.1
00100 200 300 400 500
TEMPERATURE (K)Fig. 2 T dependences of (top) field
fluctuation rate ν and (bottom)field distribution width Δ for
Li1-xNi1+xO2 with x~0.03 (opencircles), ~0.07 (red), and ~0.15(black). The data were obtained byglobal-fitting the ZF-, LF-, andwTF-spectra.

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