Intermediate Temperature Solid Oxide Fuel Cell Solid Electrolyte Is Scientific Research

Solid oxide fuel cells (SOFCs), a novel electrochemical energy conversion device, have attracted extensively studies because of their high energy efficiency, simple operation and amity to environment. The high operating temperature (1000℃) of the conventional high-temperature SOFCs caused many problems on materials choice and fabricating techniques. So it is desirable to lower the operating temperature to middle level (600-800°C), which requires either developing alternative electrolyte materials with higher conductivity to replace YSZ, or reducing the thickness of electrolyte layer.To develop intermediate temperature SOFC with lower cost and achieve practicality, this thesis focuses mainly on fabricating dense YSZ thin membranes on anode supported SOFC and characterization of the electrochemical performance. The main work includes the following sections:Chapter 1 reviews the working principle for SOFCs, the research for electrolyte materials and fabricating techniques for electrolyte films.Due to traditional solid state reaction is difficult to fabricate nanosize and high active powder and soft chemical process is difficult to wash and have high cost, electrolyte materials were prepared by using a modified solid state reaction method in chapter 2. The sintering ability and electrical properties of Ce_0.8Sm_0.2O_1.9(SDC) powders synthesized by this method have been examined. The XRD pattern confirmed the formation of the fluorite structure when SDC powders calcined at 500 ℃. The particle sizes of the powders calcined at 900℃ were in the range of 50 nm to 60 nm. The powders calcined at 700 °C were pressed into pellets and sintered in air at 1350℃ for 5h, resulting in a bulk sample with 95% theoretical density. The total conductivities of the sintered body measured by A.C. impedance spectroscopy technique were 0.046 and 0.083 S·cm^-1 at 700 and 800℃, respectively, which were equal to the literature. A pure phase dense (exceed 94%) La_0.8Sr_0.2Ga_0.83Mg_0.17O_2.815 electrolyte has been also made successfully by this method when sintered at 1450℃. The conductivity of sintered body was 0.017 S·cm^-1 measured by ac impedance...