Effect of adding urea on performance of Cu/CeO₂/yttria- stabilized zirconia anodes for solid oxide fuel cells prepared by impregnation method

Anode microstructure has a great influence on the cell performance. The addition of urea into impregnated solution has been proposed to tailor the distribution and/or morphology of Cu when fabricating the Cu-based anodes by impregnation method. While the previous reports demonstrated the single cell performance has not been improved in this route, in this paper, fuel cells with Cu/yttria-stabilized zirconia (YSZ) and Cu-CeO₂/YSZ anodes were fabricated and evaluated with improved outputs. The microstructure of Cu in anodes appeared significantly different after the addition of urea. The electronic conductivity obtained from the anodes impregnated with adding urea was twice as high as the ones without. Performance of fuel cells increases by 12% while operating on H₂ at 700 °C upon adding urea. Furthermore, the performance improvement was more prominent when such method was adopted in the fabrication of Cu-CeO₂/YSZ composite anodes. Cells with Cu-CeO₂/YSZ composite anodes operating in H₂ at 700 °C exhibited an increase of cell performance by 37%, from 337 to 462 mW cm^-2, by simply adding urea to the impregnated solution. And the performance enhancement for such fuel cells is also as high as 28% when using CH₄ as fuel.