成果報告書詳細
管理番号20130000000485
タイトル*平成24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2013/12/25
報告書年度2012 - 2012
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. Fluorine-intercalated graphites with high fluorine contents were electrochemically prepared for the cathode material and the cycling properties of graphite in solid state cells were investigated. In case of the electrolyte, PbSnF4 with a high conductivity was prepared and the chemical stability was tested.

Electrochemical fluorination of graphite in 47% HF
In order to obtain cathode materials of high capacity, graphite was electrochemically fluorinated in a 47% HF solution at high current densities. Stage 1 type CxF with an interlayer spacing of 0.58 nm was obtained at the current density of 200 mA/cm2, however, at higher current densities, graphite was not sufficiently fluorinated, probably because the surface of it was passivated by insulating graphite fluoride.

Electrochemical behavior of graphite in solid cells
The electrochemical behaviors of graphite powder were investigated by cyclic voltammetry in the Pt/PbSnF4/graphite cells. When an appropriate amount of fluoride ion conductors such as PbSnF4 were added to the graphite cathode, a pair of current peaks indicating the intercalation/de-intercalation of fluorine ions into/from graphite was clearly observed at the cell voltages of 1.5 and 1.0 V, respectively. When a certain fluoride was added, the reduction peak was observed at a higher cell voltage, which was more favorable for the additive of the battery. The reduction peak was observed 0.7 V higher than that observed for CuF2 and 3.5 V of discharge voltage is expected when graphite is combined with celium metal anode.

Preparation of a new cathode material
For the host of fluorine ions, carbons with large interlayer spacings of 0.336-0.420 nm were successfully obtained from the pyrolysis of graphite oxide at 250-900°C under vacuum. It was also possible to include lithium ions as the precursors of the catalyst in the above carbon by adding LiOH to graphite oxide before pyrolysis. The reduction peak observed during the cyclic voltammetry slightly shifted to lower voltage for the sample with an interlayer spacing of 0.42 nm.

Stability of solid electrolyte in solutions
The stability of PbSnF4 was investigated in a THF based electrolyte solution. In the UV-Vis spectrum of the solution after immersion of PbSnF4, the absorbance at 450 nm greatly increased, which indicates the dissolution of it into electrolyte solution. The IR peaks of PbSnF4 observed around 600 cm-1 also became broader after immersion in the electrolyte solution.
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