成果報告書詳細
管理番号20090000000604
タイトル*平成20年度中間年報 固体高分子形燃料電池実用化戦略的技術開発 次世代技術開発 陽電子消滅法を利用した固体高分子形燃料電池電解質膜の精密解析法の研究開発
公開日2010/3/2
報告書年度2008 - 2008
委託先名国立大学法人大阪大学
プロジェクト番号P05011
部署名燃料電池・水素技術開発部 燃料電池グループ
和文要約以下本編抜粋:1. 研究開発の内容及び成果等 (1)陽電子消滅過程の温湿度依存性の調査 最終的な劣化評価の実用化に向けて、燃料電池を実際に運転している状態を模擬し、室温から100℃程度の温度範囲において湿度を変化させて陽電子消滅寿命測定を行った。その結果、Fig.1に示すように、水蒸気圧や温度により、電子-陽電子の3重項の束縛状態であるオルソポジトロニウムの消滅寿命が変化する傾向が示された。このことは、温度変化による分子運動や湿度変化による含水に伴い、プロトン伝導に関与しているスルホ基近傍のナノ空間に変化が表れ、この変化が陽電子寿命に影響を及ぼしていることを示している。
英文要約The relationship between structural and electronic property in the vicinity of functional group of polymer electrolyte membrane (PEM) used in fuel cells was investigated by using PAS. The data of PAS was verified with other methods such as Fourier transform infrared spectroscopy (FTIR), electron spin resonance (ESR), ion exchange capacity and solution analysis to clarify degradation mechanism of PEM. To confirm the versatility of PAS, change in annihilation site of PEM caused by heat treatment and Fenton reaction which were expected to lead different degradation pathway from gamma-ray irradiation was investigated. The S-parameter showed a significant correlation with proton conductivity by both heat treatment and Fenton reaction in the same way as gamma-ray irradiation as we previously investigated, which shows that PAS can be used extensively to track the degradation process of PEM. However, the correlation between S-parameter and proton conductivity showed different slopes depending on the method of degradation. It indicates that S-parameter is also sensitive to the each degradation process, compared to other conventional techniques which can detect the early stage of degradation. These results will help to generate a database of PAS parameters which depend on the degradation process, thus, it may be possible to evaluate the degradation mechanism in membranes used in actual fuel cells using this information. ESR results showed the formation of different radical species after gamma-ray irradiation and heat treatment. ATR-FTIR indicated the main and side chain scission even in lower absorbed dose which corresponds to the early stage of degradation. In addition, degradation mechanism was investigated by solution analysis. It was concluded that the sulfide ion, fluorine ion and fragments resulting from scission of side-chain ether bond dissolves into the solution, and their ratio of chemical species changed depending on the atmosphere during irradiation. In order to measure the positron annihilation lifetime in PEM under the conditions similar to actual operation of fuel cell, positron annihilation lifetime under controlled humidity and temperature was measured. The lifetime of o-Ps, which is meta-stable condition composed of positron and electron, changed depending on temperature, and the change was remarkable than dependence on humidity, indicating that molecular motion by increasing temperature and hydration effect on the nanoscopic spatial structure around sulfonic group. This phenomenon was not observed in case of measurement at room temperature after heating, which indicates that in-situ observation using this method is important to investigate dynamic structure change by temperature and humidity. It was concluded that not only S-parameter but also lifetime give important information relating to degradation process and proton behavior in PEM, which offer a clue to elucidate the structure change in PEM by actual fuel cell operation.
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