| Project/Area Number |
07458100
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
エネルギー学一般・原子力学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
YAMADA Koichi The University of Tokyo, School of Engineering, Professor, 大学院・工学系研究科, 教授 (10260499)
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| Co-Investigator(Kenkyū-buntansha) |
温 慶茹 東京大学, 大学院・工学系研究科, 寄付講座教員
IHARA Manabu Tohoku University, Institute for Chemical Reaction Science, Research associate, 反応化学研究所, 助手 (90270884)
SAKAKI Keiji National Institute of Materials and Chemical Research, Dept.of Chemical Systems,, 主任研究員 (50272406)
CHING-RU Wen The University of Tokyo, School of Engineering, Research staff
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1996: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Sorid oxide fuel cell / Electrode reaction / Cathode / Anode / Working temperature / Electric vehicle / 低温作動 / 高発電効率 / 高出力密度 / 電極反応機構 |
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| Research Abstract |
La_<1-X>Sr_XMnO_3 was used as a porous cathode to measure overpotential while changing temperature and oxygen atmosphere. Cathode with low overpotential was made by controlling the structure of the electrode. By dissolving the electrode on the electrolyte, it has become feasible to observe the length of the Three Phase Boundary (of the electrode-electrolyte-air phase). The quantitative relationship between the TPB and the overpotential has been clarified by making a model considering adsorption and surface diffusion.
La_<1-X>Sr_XCo_<1-y>Fe_XO_3, a mixed conducting material of ion conduction and electron conduction was used to make a dense electrode on a Sm_2O_3 doped CeO_2 disk. It was clarified that adsorption on the surface rather than the diffusion of ion is the rate determining step. We made a model considering surface reaction and diffusion of oxide ion. It wa made clear from the model that the interfacial conductivity is proportional to the electrode thickness for the material having low ionic conductivity. For the material having sufficiently high ionic conductivity, the interfacial conductivity was proportional to 1/2 power of Po2. From the relationship of the electrode thickness and the overpotential of the porous electrode, the factor determining the limiting capability was discussed.
A single cell of a planer SOFC was made by using Ni/YSZ cermet as the anode. Power generation was conducted by using dry methane as the fuel at 1000ﾟC.By increasing the current density, the reaction changes from carbon deposition to oxidation of deposited carbon and finally to the direct oxidation of methane. The threshold current of the carbon deposition was proportional to the effective thickness of the electrode and also to the concentration of methane. It is decreased by lowering the operation temperature. The optimum thickness of the electrode was approximately 70-140mm. We constructed a model to predict this threshold current.
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