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成果報告書詳細
管理番号20190000000587
タイトル*2018年度中間年報 革新型蓄電池実用化促進基盤技術開発(国立大学法人名古屋工業大学)
公開日2019/6/14
報告書年度2018 - 2018
委託先名国立大学法人名古屋工業大学
プロジェクト番号P16001
部署名次世代電池・水素部
和文要約
英文要約Research & Development Initiative for Scientific Innovation of New Generation Batteries 2 (RISING2); (FY2016-FY2020) FY2018 Annual Report, Nagoya Institute of Technology, Japan

In this fiscal year, (i) we performed X-ray anomalous scattering on the ZnO + KOH solution, which is used as the electrolyte of the Zn-air battery. Also, (ii) we analyzed the structure of ethyl carbonate (EC) and ethyl methyl carbonate (EMC) for bulk and interface regions. The details are described below.
(i) X-ray anomalous scattering on the electrolyte of Zn-air battery
We measured the X-ray anomalous scattering of 0.5 M ZnO + 4 M KOH solution. The measurements were performed at BL28XU of SPring-8. We adopted a poly ether ether ketone film as an X-ray window. The incident energies were set to 9.635 kev and 9.415 keV, which are just below the Zn K-edge of 9.659 keV. We successfully obtained structure factors, S(q), for each energies. The S(q) obtained in the case of 9.635 keV is slightly smaller than that in the case of 9.415 keV. This difference can be attributed to the effect of anomalous dispersion of Zn. From this difference, we will derive the local structure around Zn.
(ii) Structural analysis of EC/EMC electrolyte
(ii)-a. Bulk region
We performed X-ray total scattering measurements for EC/EMC and EC/EMC + LiPF6 solutions. The variation in the pair distribution function (PDF) was observed by adding LiPF6. To understand this variation, we performed a first principle calculation in collaboration with AIST theoretical group. It was revealed that the variation in the PDF induced by adding LiPF6 is due to the stretching and shrinking of C-O bonds accompanied by the formation of Li+ solvation.
(ii)-b. Interface region
So far, we have developed a sample cell for analyzing structure of electrolyte near the electrode interface. In this fiscal year, the cell was upgraded for measurements during charging and discharging. We prepared a Li deposition film on the SiC substrate and inserted to the cell. The LiPF6 + EC/EMC electrolyte was injected to the sample space and consequently the Li/electrolyte interface was formed. In the grazing incidence geometry, X-rays below the critical angle are totally reflected by the electrolyte-side of this interface, because the density of Li is lower than the electrolyte. Also, a Li counter electrode was put in the cell.
Using this cell we measured reflectivity curve during discharging. Total reflection was clearly observed, which demonstrates the feasibility of this method. As the cell discharges, the critical angle increases and the intensity decreases, which indicates the increase in the density of electrolyte and enhancement of the surface roughness. This behavior might be related to the formation of solid electrolyte interphase. We also measured the diffraction pattern under the condition that the total reflection on the electrolyte occurs. The analysis of this data is now in progress.
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