成果報告書詳細
管理番号20140000000240
タイトル*平成25年度中間年報 革新型蓄電池先端科学基礎研究事業 革新型蓄電池先端科学基礎研究開発 (10)
公開日2014/5/17
報告書年度2013 - 2013
委託先名公立大学法人兵庫県立大学
プロジェクト番号P09012
部署名スマートコミュニティ部
和文要約
英文要約 In this study, cathode and electrolyte materials used for the batteries based on fluoride shuttle are investigated in detail. Fluoride A with high fluorine contents were electrochemically prepared for the cathode material and the charge-discharge properties of them in solid state cells were investigated. In case of the electrolyte, fluoride B with a high conductivity and La substituted BaF2 were prepared and the surface of fluoride B was coated with more stable fluoride C film.

Properties of fluoride A obtained by the electrochemical fluorination in 47% HF
The fluorine contents of various fluoride A samples were estimated from their capacities observed in Li primary cells. The content of fluorine in fluoride A reached a very large value of 0.63 per host material. The chemical bonding in the fluoride A samples was relatively strong, based on the XPS analysis.

Electrochemical behavior of fluoride A in solid state electrochemical cell
The electrochemical behaviors of the above fluoride A as a cathode of solid state cell were investigated. When an appropriate fluoride ion conductor was added, it showed a plateau around 1V vs Pb counter electrode during discharge and charge, suggesting that reversible reaction occurred. The first discharge capacity reached 55 mAh/g. On the other hand, when fluoride ion conductors with lower stability were added, a plateau during discharge was observed at lower voltages, as the result of the reaction of fluoride A with fluoride ion conductors.

Characterization of a new cathode material
For a new host of fluorine ions, a material with a lattice parameter of 0.42 nm obtained from the pyrolysis of material D was tested in the solid state cell. It showed 35 mAh/g of reversible capacity during the 1st cycle.

Preparation of solid electrolytes
Fluoride B with a high conductivity of 10-3 S/cm at room temperature was successfully prepared by the solid state method using fluorides D and E as starting materials. Fluoride B pellet was coated by fluoride C with a higher stability using pulsed laser deposition (PLD) method. The thickness of the coated fluoride C layer reached 1.5μm and the ionic conductivity of the resulting sample was almost identical to that of the pristine fluoride B.
La doped BaF2 powders were also prepared by the sol-gel method using trifluoroacetic acid as a fluorine source. Single phase Ba1-xLaxF2+x with x=0.1-0.4 were successfully obtained.
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