Composite cathode based on yttria stabilized bismuth oxide for low-temperature solid oxide fuel cells

Composites consisting of silver and yttria stabilized bismuth oxide (YSB) have been investigated as cathodes for low-temperature honeycomb solid oxide fuel cells with stabilized zirconia as electrolytes. At $\text{600\hspace{0.05em}°}\mathrm{C},$ the interfacial polarization resistances of a porous YSB–Ag cathode is about $\text{0.3\hspace{0.17em}Ω\hspace{0.05em}}{\mathrm{cm}}^2,$ more than one order of magnitude smaller than those of other reported cathodes on stabilized zirconia. For example, the interfacial resistances of a traditional YSZ–lanthanum maganites composite cathode is about $\text{11.4\hspace{0.17em}Ω\hspace{0.05em}}{\mathrm{cm}}^2$ at $\text{600\hspace{0.05em}°}\mathrm{C}.$ Impedance analysis indicated that the performance of an YSB–Ag composite cathode fired at $\text{850\hspace{0.05em}°}\mathrm{C}$ for 2 h is severely limited by gas transport due to insufficient porosity. The high performance of the YSB–Ag cathodes is very encouraging for developing honeycomb fuel cells to be operated at temperatures below $\text{600\hspace{0.05em}°}\mathrm{C}.$