EFFECTS OF CERIA ADDITION ON NICKEL/YSZ ANODES IN SOLID OXIDE FUEL CELLS OPERATING ON HYDROGEN AND SYNGAS FUEL FEEDS
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Anode-supported solid oxide fuel cells (SOFCs) utilizing Ni/Ceria-YSZ composite anode architectures were designed, built, and tested on hydrogen and syngas fuel feeds to evaluate the effect of adding ceria (CeO2) to Ni/YSZ anodes. All anodes were approximately 1.0 mm thick and composed of two layers: a thick, high-porosity support layer and a thin low-porosity (20-30%) functional layer, 20 to 25 μm thick. Three different anode architectures containing CeO2 were tested and compared with each other and with a baseline Ni/YSZ anode. CeO2 containing cells made using a co-firing method of fabrication produced maximum power densities of 0.60 and 0.33 W/cm2 for operation on syngas while the Ni/YSZ cell produced 0.26 W/cm2. Comparison of the high and low frequency arcs observed in the impedance spectra (attributed to the anode and cathode respectively) indicate that a reduced anode polarization resistance for cells containing CeO2 is due principally to improved microstructure in the anode support layer. However, for syngas operation there is also evidence that improved electrocatalytic activity with the H2 and CO mixture occurs with CeO2 present in the anode support and/or functional layers.