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成果報告書詳細
管理番号20190000000571
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(国立大学法人九州大学)
公開日2019/6/11
報告書年度2018 - 2018
委託先名国立大学法人九州大学
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Title:Research and Development Initiative for Scientific Innovation of New Generation Batteries 2 (RISING 2) (FY2016-FY2020) FY2018Annual Report,Kyushu University, Japan

Fluoride-shuttle batteries have extremely-large capacity and maximum theoretical energy density. In addition, F- have advantage in the rate capability compared with multivalent ions such as Mg2+ and Al3+. In this project, we focused on the perovskite-related fluoride. Firstly, we prepared the various perovskite-related fluoride by mechanical milling method. As a result, a lot of the target materials were successfully prepared without impurity phase. The electrical conductivity of the prepared material was evaluated by the AC impedance method. Some of the perovskite fluorides showed high electrical conductivity.

Effects of Fe, Cu, or Mn doping for NiCo2O4 on oxygen reduction (ORR) and oxygen evolution reaction (OER) and also preparation of mesoporous NiCo2O4 spinel oxide doped with Fe were studied for rechargeable Zn-air batteries. Comparing the prepared spinel oxides, it was found that the ORR/OER activity of NiCo2O4 was reasonably high and stably cycled. Cycle stability was further increased by doping 20 mol% Fe on Ni site in NiCo2O4. At 60 mA/cm2, overall ORR capacity was achieved to 8,000 mAh/cm2 at 40 °C which is slightly lower than the final objective value. Mesoporous NiCo2O4 was successfully prepared by using spray pyrolysis method and the obtained mesoporous Ni(Fe)Co2O4 showed the BET surface area of 68 m2/g and overpotential of NiCo2O4 to ORR/OER was much decreased. A Zn-air battery was prepared by using mesoporous MnCo2O4 as air electrode and 4 M KOH aqueous electrolyte, the stable charge/discharge cycles were sustained more than 250 cycles.

In this fiscal year, in order to improve the electrochemical performances of FeF3 composite cathode with amorphous V2O5 vanadate glass, the following factors were investigated;

1) Electrolyte dependency of the cyclability
Typical organic electrolytes (1 M LiPF6/EC: DMC = 1: 1 (v/v), 1 M LiPF6/EC: EMC = 1: 1 (v/v), 1 M LiClO4/EC: DMC = 1: 1 (v/v), 1 M LiClO4/EC: EMC = 1: 1 (v/v)) were investigated. As a result, the electrolytic solution salt had almost no influence on the cycle characteristics. However, by changing the solvent from DMC to highly hydrophobic EMC, the cycle retention was improved.

2) Temperature dependency of the cyclability
As a result of the evaluation at an operating temperature of 60 °C. using LiTFSA: G 4 = 1: 1 (molar ratio) electrolyte, the initial discharge capacity was 551 mAh/g and the capacity retention ratio after 15 cycles was improved to 84 %.

3) The adding effect of LiF sacrificial salt for reduction of the irreversible capacity
It was found that the addition of 8.9 wt% LiF can completely compensate irreversible capacity.
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