成果報告書詳細
管理番号20100000001288
タイトル*平成21年度中間年報 固体酸化物形燃料電池システム要素技術開発 耐久性・信頼性向上に関する基礎研究 三相界面についての劣化現象と微細構造変化の相関付け
公開日2011/5/10
報告書年度2009 - 2009
委託先名国立大学法人東京大学大学院工学系研究科
プロジェクト番号P08004
部署名新エネルギー部
和文要約電気化学反応の舞台となる三相界面について、電極反応に影響を及ぼす因子を電極微細構造との関連から明確にすることを目的に、これらの知見をシミュレーション手法と組み合わせて、電極材料、電極作製法、電極構造、運転条件等の提言を行う。本年度は3次元微構造の直接測定とデータベースの構築と、3次元微構造データに基づくシミュレーション技術開発を実施した。
英文要約Title: Development of component technologies for solid oxide fuel cell system/ Basic research on durability and reliability/ Relationship between degradation phenomena and microstructure at three phase boundary (FY2008-FY2010) 2009 Annual Report
Three dimensional microstructures of Ni-YSZ anode and LSCF cathode were reconstructed by FIB-SEM (Karl Zeiss, NVision40). Carbon paste was used to get good electric connection with the stage. Microstructural parameters such as three phase boundary (TPB) length, specific area and tortuosity factor were obtained. In order to obtain quantitative TPB length, centroid method was proposed. It was confirmed that the centroid method gives less than 3% error compared to the volume expansion method. Tortuosity factors are calculated by solving diffusion equations along x, y and z directions. Tortuosity factor of pore phase was independent on volume size, while that of the Ni phase showed large variations depending on the sample volume and location. Tortuosity factor of YSZ phase showed asymptotic value when the cross sectional area was larger than approximately 200 square microns. For LSCF cathode, specific area was calculated by the marching cube method. Tortuosity factor of LSCF also became nearly constant when cross sectional area exceeded 200 square microns. Three dimensional potential fields inside the reconstructed three dimensional structures were calculated by the Lattice Boltzmann Method (LBM). For Ni-YSZ, electrochemical reaction was assumed at three phase boundary, while solid-gas interface reaction it was assumed for LSCF cathode. Predicted results were compared with the experimental data. Dependence on steam partial pressure was not quantitatively predicted for the anode. Finally, redox cycle experiment of Ni-YSZ anode was conducted by discharging ionic current to the anode. Spongy like Ni structure was obsereved in case of dry N2 atmosphere, while Ni agglomeration was observed in the case of humidified N2.
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