| dc.description.abstract | In this study, the SrCeO3-based and BaCeO3-based perovskite ceramic materials with high proton conductivity were developed which can applied on hydrogen transport membranes (HTM) and solid oxide fuel cells in its high- and intermediate- working temperature. The proton-conducting SOFC (P+-SOFCs) can operate at relatively low temperature (500–800°C) because of their higher conductivity, lower activation energy, and reduces the capital costs and prolongs cell lifetime. The hydrogen, is the source for SOFC, can be obtained by separation and purification of methanol, natural gas and fossil fuels.
Firstly, according the published result of hydrogen transport membranes research, SrCe1-xZrxO3?δ (0.0 ? x ? 0.5) proton-conducting oxides can be successfully prepared using a solid state reaction method. In this study, the effect of the Zr contents on the microstructures, shrinkages, and sintering of these SrCe1-xZrxO3?δ (0.0 ? x ? 0.5) were systemically studied by using X-ray Diffraction, Scanning Electron Microscopy, and Thermal dilatometer analysis (TDA). The SEMs shows that the porosities of sintered SrCe1-xZrxO3?δ increased with increasing the Zr contents. The largest porosity about 27.53% could be obtained at the SrCe0.6Zr0.4O3-δ ceramics sintered at 1500oC for 2 h. Meanwhile, a flat HTM with porous supporting layers of SrCe0.6Zr0.4O3-δ and SrZrO3 was fabricated by constrained sintering. Therefore, the SrCe0.6Zr0.4O3-δ ceramic is suggested to be a potential support layer material without pore former addition and complex sintering process for HTM and hydrogen purification applications.
Second, according the published result of P+-SOFC research, Ba0.8Sr0.2Ce0.6Zr0.2 InxY0.2-xO3-δ proton-conducting oxides are prepared using a solid state reaction process. The effect of indium contents on the microstructures, chemical stability, electrical conductivity, and sintering ability of these Ba0.8Sr0.2Ce0.6Zr0.2InxY0.2-xO3-δ oxides were systemically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and two probe conductivity analysis. A dense microstructure Ba0.8Sr0.2Ce0.75In0.05Y0.2O3-δ oxide can be prepared by sintering at 1450°C for 4 h which decreased about 200°C sintering temperature. Meanwhile, the optimum conductivity of Ba0.8Sr0.2Ce0.75In0.05Y0.2O3-δ oxide is 0.011 S cm-1 measured at 800°C. In order to enhance the performance of proton-conducting solid oxide fuel cell, the electrolytes and anodes were further improved by modifying the fabrication process. In this study, the laminated electrolyte of Ba0.8Sr0.2Ce0.75In0.05Y0.2O3-δ and anode layers which fabricated by tape casting and co-sintering. The sintered half-cell coated with Pt paste as cathode was prepared for anode supported electrolyte single cell. The effect of NiO contents on the microstructures, surface area, and electric conductivity of these Ni-Ba0.8Sr0.2Ce0.6Zr0.2Y0.2O3-δ anode materials were systemically investigated by tuning the optimum combination of NiO and electrolyte for fabricating the anode materials. The porous structure for the anode substrates not only provide the mechanical strength to the fuel cells, but also allow the fuel gases flow to the electrolyte membrane. On the other hand, the results of cell performance reveal that the powder density of the single cell increases two times with decreasing the thickness of electrolyte layer from 60 m to 20 m. The power density of single cell reaches to 314.2, 259.5, and 150 mW cm-2 at 800, 700, and 600°C, respectively. In this study, the reducing electrolytes process is helpful for proton-conducting solid oxide fuel cells applications.
Therefore, the anode supported proton-conducting electrolyte solid oxide fuel cells were fabricated and evaluate their performance and stability in H2/CO syngas with different ratio of hydrogen (H2), carbon monoxide (CO) fuels was investigated in this study. It was found that inceasing the CO-containg feed streams with decreasing hydrogen gas would gradually degrade the performance of the P+-SOFC. In addition, the carbon deposition will block the nickle catalyst reaction in the anode during the cell testing in CO-containg fuels surrroundings. Therefore, it was showed that the Ba0.8Sr0.2Ce0.75In0.05Y0.2O3-δ ceramic of P+-SOFC possess not only high protonic conductivity but also good chemical stability. In the future, we will try to fabricate the planar P+-SOFC single cell and P+-SOFC stack interconnect components. Moreover, we expect to establish the process window of fabricating the high performance anode supported P+-SOFC single cells. | en_US |