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    首頁> 外文學位 >Thin film mixed conducting cathodes for intermediate temperature solid oxide fuel cells.
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    Thin film mixed conducting cathodes for intermediate temperature solid oxide fuel cells.

    機譯:用于中溫固體氧化物燃料電池的薄膜混合導電陰極。

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    摘要

    This work was focused on the processing and characterization of thin (200--300 nm) film La0.6Sr0.4Co0.2Fe 0.8O3-delta-Ce0.8Gd0.2O2-delta (LSCF-CGO) composite cathodes to achieve low polarization resistances at reduced temperature (300--600°C). A single precursor solution was employed to process the LSCF-CGO films by spray pyrolysis. The films were deposited on YSZ substrates to simulate the electrolyte/cathode interface in micro-scale SOFCs. A solution of nitrate salts dissolved in a mixture of ethanol and diethylene glycol was sprayed on a sintered YSZ laminate held at 235°C. The as-deposited films were amorphous and were heated to 500--900°C for crystallization to occur. Phase segregation was observed by x-ray diffraction upon annealing above 600°C. Grain growth in the LSCF-CGO films was followed at 700--900°C and occurred to lesser extent than in LSCF films due to the CGO phase. The polarization resistance of the films with 0, 41, 66 and 100 vol% CGO fraction and annealing temperatures ranging from 500 to 900°C was studied by impedance spectroscopy at 350--600°C. Several models proposed for mixed conducting cathodes were examined. A model for co-limitation of oxygen diffusion and surface exchange processes was selected based on fit quality and confidence interval of parameter estimates. The magnitude and activation energy of the polarization resistance decreased with CGO addition, which was consistent with the properties of CGO. The resistances of LSCF and 59LSCF-41CGO films annealed at 700°C were 17 and 9 ohm.cm2 at 500°C. The variation of polarization resistance with increasing annealing temperature displayed a "v" shaped curve in the 300--500°C operating temperature range. The resistance of 59LSCF-41CGO films annealed at 500, 700 and 900°C were 290, 106 and 256 ohm.cm2 respectively, at 400°C. The respective activation energies estimated over the 350--600°C operating temperature range were 1.45, 1.11 and 1.04 eV. The films annealed at 500--600°C displayed a mixed amorphous-crystalline structure with very fine crystallites which may explain their higher activation energies. For applications to micro-SOFCS, these films require operating temperatures of 600°C to achieve low polarization resistances.
    機譯:這項工作專注于處理(200--300 nm)薄膜La0.6Sr0.4Co0.2Fe 0.8O3-del-Ce0.8Gd0.2O2-delta(LSCF-CGO)復合陰極以實現低極化電阻的特性降低溫度(300--600°C)。采用單一前體溶液通過噴霧熱解法處理LSCF-CGO薄膜。將膜沉積在YSZ基板上,以模擬微型SOFC中的電解質/陰極界面。將溶解在乙醇和二甘醇的混合物中的硝酸鹽溶液噴霧到保持在235℃的燒結YSZ層壓板上。沉積后的薄膜是非晶態的,并加熱到500--900°C進行結晶。在高于600℃的退火下通過X射線衍射觀察到相偏析。 LSCF-CGO薄膜的晶粒生長在700--900°C下進行,并且由于CG??O相的發生,其生長程度低于LSCF-CGO薄膜。通過阻抗譜在350--600°C下研究了CGO分數為0、41、66和100%(體積),退火溫度為500至900°C的薄膜的極化電阻。研究了幾種建議用于混合導電陰極的模型?;跀M合質量和參數估計值的置信區間,選擇了一個限制氧氣擴散和表面交換過程的模型。極化電阻的大小和活化能隨加入CGO而降低,這與CGO的性質是一致的。在700°C退火的LSCF和59LSCF-41CGO薄膜在500°C時的電阻分別為17和9 ohm.cm2。極化電阻隨退火溫度的升高而變化,在300--500°C的工作溫度范圍內呈“ v”形曲線。在500°C,700°C和900°C下退火的59LSCF-41CGO膜的電阻在400°C下分別為290、106和256 ohm.cm2。在350--600°C工作溫度范圍內估計的各自活化能為1.45、1.11和1.04 eV。在500--600°C退火的薄膜顯示出混合的無定形晶體結構和非常精細的微晶,這可以解釋其較高的活化能。為了應用于微型SOFCS,這些薄膜需要600°C的工作溫度才能實現低極化電阻。

    著錄項

    • 作者

      Angoua, Bainye Francoise.;

    • 作者單位

      Purdue University.;

    • 授予單位 Purdue University.;
    • 學科 Energy.;Engineering Materials Science.
    • 學位 Ph.D.
    • 年度 2010
    • 頁碼 118 p.
    • 總頁數 118
    • 原文格式 PDF
    • 正文語種 eng
    • 中圖分類
    • 關鍵詞

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