Performance Improvement Of Ceria-Based Electrolyte Intermediate-temperature Solid Oxide Fuel Cells By Novel Composite Cathode And Thin Electrolyte

Solid oxide fuel cells(SOFCs) are solid-state electrochemical device that convert the chemical energy of reaction directly into electrical energy. It possesses several distinct advantages, such as environmental friendship, higher conversion efficiency and broad adaptive fuels, which is a new green energy developed in the world for 21 century. Yttrium stabilized zirconia(YSZ) is the most commonly used electrolyte in SOFCs. Limited by its oxygen ion conductivity, ZrO2-based SOFCs must operate at about 1000°C. So exploring new type of electrolyte and electrode and their synthesis method is very important for developing IT-SOFC. Now, ceria-based electrolytes are noteworthy as candidates for electrolyte materials. And the most commonly used synthesis techniques for SOFC components are solid state reaction, co-precipitation reaction, hydrothermal synthesis route and sol-gel method. These methods have some shortcomings, such as complex, slowly or composite phase inhomogeneous. "Glycine-nitrate process"(GNP)synthesis technique is simple and speedy. Single-or multi-component oxide powders can be prepared rapidly and simply using the GNP. The method immediately produces high-surface-area, compositionally homogeneous powers, usually with low levels of residual carbon. Therefore, in this study, we prepared all the compoments for a ceria-based single medium-temperature cell by the glycine-nitrate process and give a report on the performance of the cell. The system Ce0.9Sm0.1O1.95(SDC) was chosen as the electrolytes, Samaria-doped ceria-NiO composite powder as the anode and La0.6Sr0.4Fe0.8Co0.2O3-SDC(LSCF-SDC) as composite cathode. The XRD patterns show that the glycine-nitrate combustion products were all crystals directly. The electrolyte prepared by combustion process can form compact pellet after sintered at 1400°C for 4h. This phenomena is due to the foam-phase, loose nano-particle powders with super high ratio surface area synthesized by combustion. Such materials enhance the sintering drive power, increase the diffuse rate and shorten the diffuse distance, then fasten the sintering process greatly. The SEM shows the SDC sample is reasonably dense with a little micro cracks, the boundaries tend to merge and become blurred. The SOFC test shows at 750°C the output voltage reach 0.761V, and the maximum power density of 124mW/cm2 and a short circuit current density of 513.73mA/cm2 are obtained. So these materials are good electrolyte used in SOFCs, the sample's performance is good enough to meet the requirement for application. When the working temperature of the SOFCs is lowered, there must solve a followed problem of the cathode polarization. Made a composite cathode LSCF-SDC by mixing LSCF with samarium doped ceria (SDC). While the...