| Summary: | 碩士 === 國立中央大學 === 材料科學與工程研究所 === 105 === To protect proton-conducting solid oxide fuel cells (H+-SOFCs) from CO2 poisoning and to have basically ion conductivity, the sandwich structure of BaCe0.6Zr0.2Y0.2O3-δ/BaCe0.8Y0.2O3-δ/BaCe0.6Zr0.2Y0.2O3-δ was used in this study. BaCe0.8Y0.2O3-δ (BCY) and BaCe0.6Zr0.2Y0.2O3-δ (BCZY) powders were synthesized by solid-state reaction method (SSR). After sintering, BCY, BCZY and the sandwich samples were analyzed by scanning electron microscope (SEM), x-ray diffraction (XRD) and conductivity measurements.
The SEM images showed that the electrolytes were highly dense after sintering at 1550℃ for 12 hrs, indicating that the fuel leakage could be ignored. The thicknesses of BCY, BCZY and the sandwich structures were well controlled. The six main peaks (110), (200), (211), (220), (310), and (222) shown in the XRD patterns confirmed the perovskite phase. After poisoning treatment in CO2 atmosphere at 600℃, BCZY and the sandwich structure showed higher stability than that of BCY.
The conductivity of the sandwich structure (800℃,0.0026 S/cm) was found to locate between BCY (800℃,0.0027 S/cm) and BCZY (800℃,0.0018 S/cm). After poisoning treatment, the BCY conductive value obviously decreased (800℃,~0.0006S/cm) since the second phase hindered its ion transferring. The sandwich structure almost maintain its conductivity because its protection layers slowed down the pensioning process (800℃,~0.0019S/cm). However, all conductive values were smaller than the values in the previous study. It would be attributed to the contact resistances between electrolyte and metal contacts.
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