成果報告書詳細
管理番号20110000001106
タイトル*平成22年度中間年報 固体高分子形燃料電池実用化推進技術開発 次世代技術開発 微細孔内精密ミクロ構造制御と界面高速プロトン伝導現象を用いた広温度・無加湿型PEFCの開発
公開日2011/10/12
報告書年度2010 - 2010
委託先名国立大学法人東京工業大学
プロジェクト番号P10001
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等 自動車用の固体高分子形燃料電池(PEFC)は、-30℃での起動、無加湿での運転が可能で、かつスタックの中で想定される広い湿度領域、常温から100℃までの幅広い温度領域で安定した性能を示す必要がある。また、将来的にMEAとしたときの耐久性、低コスト生産性に結びつくことも重要な点である。これらの要請を、ビークル機構でプロトンが伝導する従来のパーフルオロスルホン酸系ポリマーを用いた電解質材料の開発の延長線上で達成することは難しい。
英文要約Title: Non-humidified PEFCs under broad temperature range operation using rapid proton conduction at hetero-phase interface and micro-scale control of electrolyte structure (FY2010-FY2011) FY2010 Annual Report
Novel electrolyte materials showing reasonable proton conductivity under non-humidified condition and broad temperature range are highly required for the practical polymer electrolyte fuel cells (PEFCs). These properties are difficult to achieve by conventional proton conductors such as perfluorosulfonated polymer whose proton conduction occurs via vehicle mechanism. We utilize rapid proton conduction at hetero-phase interface and control the micro-scale structure of the electrolyte to enable non-humidified and broad temperature range operation of PEFCs. The rapid proton conduction occurs in a capping proton conductor made by multipoint inter-adsorption of an electrolyte polymer to a nano-sized inorganic proton conducting particle. We have already shown that the proton conductor had higher proton conductivity than the sum of the pure electrolyte polymer and the pure inorganic particle. However, the mechanism of the rapid proton conduction is still unknown. In this research, we clarify the detailed mechanism of the rapid proton conduction at hetero-phase interface of the proton conductor, and develop a pore-filling membrane composed of the proton conductor and a porous substrate to control the micro-scale structure of the electrolyte. In this year, to control the properties of the hetero-phase interface, highly acidic zirconium sulphate (ZrS) was synthesized from the surface-modified nano zirconium oxide precursor. The precursor has been converted to zirconium phosphate (ZrP) and zirconium sulfophenylphosphonate (ZrSPP), and is known to form a nanodispersed structure in polymer electrolytes. The dependence of the proton conductivity of ZrS with respect to RH was much smaller than that of ZrP and ZrSPP, which is unique and attributable to the high water-retention capacity of ZrS, as shown by thermogravimetric analysis. Then, the quantum chemical calculation is carried out to clarify the proton conduction mechanism at molecular level. The proton transfer on the surface of ZrP was investigated. Density functional theory calculations show that phosphate groups contribute to high conductivity by making strong hydrogen-bond network on ZrP surfaces. These strong hydrogen-bond networks and sufficient number of phosphate groups on ZrP surfaces make O-O distance shorter on the surface and improve proton conductivity at the hetero-phase interface of electrolyte. Then, the pore-filling membrane was fabricated by filling the electrolyte made of sulfonated poly(arylene ether sulfone) (SPES) and the zirconium oxide precursor into the submicron pores of the porous substrate. The precursor was converted in situ to ZrSPP. The mechanical strength of the capping pore-filling membrane and the hydrothermal stability of the capping pore-filling membrane were assessed. The pore-filling membrane made of ZrSPP and SPES showed no appreciable change in proton conductivity as a function of RH from 20% RH to 80% RH at 90 C, the value at 20% RH and 90 C being 0.06 S/cm.
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