Processing and characterization of anode materials for solid oxide fuel cells

Many efforts have been devoted to the low-temperature operation of solid oxide fuel cells. Yttria-stabilized zirconia is widely used as a solid electrolyte for oxygen ions at around 1000degreesC. A ceria-based electrolyte may decrease the operating temperature because of its higher electrical conductivity. In this research, the processing of anode material for rare-earth-doped ceria ceramics was studied. Ni powder and Sm-doped ceria powder prepared by an oxalate coprecipitation method were mixed at different volume ratios and sintered in air at 1300degreesC. The sintered cermet was annealed in a mixed hydrogen/argon atmosphere for 10 h at 400degreesC. The electrical conductivity was measured at 25degrees-200degreesC in air for the sample before and after the annealing. Compared with the as-sintered sample, the electrical conductivity of the sample after the annealing became very high due to an increase of electronic conduction by the Ni. The electrical conductivity increased with an increase of Ni content because of the formation of a network of nickel in the matrix of Sm-doped ceria.