A-site deficient lanthanum ferrites as cathode materials for SOFCs

Abstract

Several (La,Sr)(Co,Fe)O3-δ perovskites were evaluated for their use as SOFC cathodes. Emphasis was placed on the effect of a small A-site deficiency on the properties of these perovskites. It was found that the A-site deficient compositions possess an increased sintering activity. This was more pronounced for the cobalt-containing perovskites than for pure ferrites. The perovskites were also used as cathodes of SOFC single cells to determine the electrochemical properties. The performance of the perovskites with a small A-site deficiency was significantly increased in comparison to the stoichiometric composition. This effect was stronger for the cobalt-containing materials. Increased Sr-substitution on the A-site and the addition of cobalt on the B-site also led to an enhanced performance. The composition with the highest electrochemical activity was La0.58Sr0.4Co 0.2Fe0.8O3-δ. SOFCs with these cathodes achieved power densities of up to 1.0 W/cm2 at 0.7 V and 750°C with hydrogen as the fuel.