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
2018/3/22

課題番号 Project No.

装置責任者 Name of responsible person

2017A0039

Toru Ishigaki

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Crystal Structure Refinement and Electrochemical Properties of theiMATERIA/BL20

Spinel-Type New Cathode Material of MgCo2-xNixO4 for

実施日 Date of Experiment

Magnesium Secondary Battery

2017/5/22

実験責任者名 Name of principal investigator

2017/10/30 - 2017/11/01

Yasushi Idemoto
所属 AffiliationTokyo University of Science
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.

Compositions: MgCo2-xNixO4 (x = 0.2, 0.3, 0.4, 0.6, 0.8, 1.0)
Physical form: Powder

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
MgCo2O4 and MgCo2-xNixO4 (x = 0.2, 0.3, 0.4, 0.6, 0.8, 1.0) were synthesized by a reverse
coprecipitation method and subsequently solid state reaction at 350 °C. The samples were identified by powder
X-ray diffraction measurements, and their metal compositions were evaluated by Inductively Coupled Plasma(ICP) emission. In order to clarify how the substitution of Ni to Co affected the electrochemical properties aftercharge and discharge in detail, we performed charge and discharge tests with a 5 mA/g. First of all, we focused on
the structure changes after the first discharge in this work, and thus prepared electrodes after the first discharge,
for neutron diffraction measurements.
Neutron diffraction patterns of the synthesized powders and these cathodes were measured by iMATERIA.
Each cathode after the discharge was separated from an Al substrate, and then loaded into a V can. The
measurements were carried out at room temperature with a SF mode, and data were collected by using all thebanks. Crystal structures of the cathodes were refined by a Z-Rietveld program. For the pristine powders, we also
performed the analysis using the Synchrotron X-ray diffraction with BL19B2 at SPirng-8.
1

2. 実験方法及び結果（つづき） Experimental method and results (continued)
Results
The synthesized MgCo2-xNixO4 (x = 0.2, 0.3, 0.4, 0.6, 0.8, 1.0) were identified by XRD and ICP. The XRD
patterns were characteristic of the broad peak derived from small particle size. Since the neutron diffraction patterns also
weak diffraction peaks in spite of relatively long measured time, the Rietveld analyses were performed using the bothdata from neutron diffraction in SE bank and from synchrotron XRD at SPring-8. The analyzed profiles ofMgCo1.7Ni0.3O4 were shown in Fig. 1.
The site occupancies at 8a and 16d sites regarded as Mg site and transition metal (Co, Ni) site, respectively, wererefined with the constraints on the mixing of Mg, Co and Ni. Although the tendency between the Ni compositions andthe cation mixing contents was not obtained in the results of Rietveld analysis using only neutron diffraction data, thelinear correlation was clearly recognized by using the neutron and the synchrotron X-ray diffraction data (Fig. 2). Since
the neutron can distinguish Ni from Co and the synchrotron X-ray gives the strong diffraction peaks over wide d range,
the collaborative use of neutron and X-ray is extremely effective for the structural refinement of the MgCo2-xNixO4.

Fig. 1 Rietveld analysis for (a) neutron diffraction data and (b) synchrotron XRD data of MgCo1.7Ni0.3O4. The reliability
factors in Rwp were 1.87 % and 4.35 % for neutron diffraction and synchrotron XRD, respectively.

Fig. 2 Refined occupancies at (a) 8a site and (b) 16d site for the Ni compositions. The structure refinements wereperformed using the neutron and the synchrotron diffraction data.

2