Composite anodes for utilization of hydrogen and methane fuels in intermediate-temperature solid oxide fuel cell

Solid Oxide Fuel Cells (SOFCs) with the advantages of high fuel efficiency, low greenhouse emission, and multiple fuel choice are a promising technology for large-scale power generation. However, there are several major barriers for SOFC commercialization, e.g. high cell material cost and requirement of pure H2 as the fuel in most SOFCs. This research work focused on intermediate-temperature SOFC (IT-SOFC) directly operating on both hydrogen and methane fuels. The main goal was to make SOFC more competitive by reducing the cost for both anode material and fuel processing.;Firstly, the perovskite phase (La,Sr)(Ga,Mg)O3 (LSGM) was optimized as the electrolyte material. LSGM with various compositions was thoroughly evaluated and several compositions with the best properties were identified. The optimized LSGM was then employed as the electrolyte support for evaluating the different anodes via fuel-cell testing.;Secondly, composite materials of Sm2O3-doped CeO 2 (SDC) with various Ni-Fe alloys were synthesized and evaluated as the high-performance anode with H2 fuel. It was found that the composite anodes with Ni0.8Fe0.2 and Ni 0.75Fe0.25 alloys showed better performance than pure Ni at 800°C. Further work was done by substituting SDC in the composite anode with Y2O3-stabilized ZrO2 (YSZ) to provide mechanistic understanding regarding the "Fe" effect in the Ni-Fe alloy.;Thirdly, (La,Sr)(Cr,Mn)O3 (LSCM) impregnated with Cu and Cu-Pd was evaluated as the anode for direct utilization of CH4. Impregnation of Cu into porous LSCM anode was found to significantly improve the cell performance in both dry H2 and CH4. The performance was further enhanced with the impregnation of a small amount of Pd into the anode. The mechanism of methane oxidation on the LSCM, LSCM + Cu, and Pd-dispersed LSCM + Cu anodes was discussed. Y-doped SrTiO3 (SYT) combined with La 2O3-doped CeO2 (LDC) was also chosen as a composite anode for direct utilization of methane. The performance of the composite anodes with and without Ni impregnation in both H2 and methane was investigated.;Fourthly, a new amorphous LaMoO material was identified and investigated as the sulfur-tolerant anode for SOFC. LaMoO was obtained by reducing the ionic conductor La2Mo2O9 in SOFC anodic atmosphere. Single cell with the LaMoO anode exhibited relatively high power density in dry H2. Essentially no decay in cell performance was observed over 100 h in both pure H2 and H2 containing up to 20 ppm H2S, indicating that the amorphous material is a potential sulfur-tolerant anode.