Dopants to enhance SOFC cathodes based on Sr-doped LaFeO3 and LaMnO3

Abstract

The influence of various infiltrated dopants on the performance of solid oxide fuel cell (SOFC) cathodes was examined. The cathodes were prepared by infiltration of nitrate salts into porous yttria-stabilized zirconia (YSZ) to produce composites with 40-wt% of either La0.8Sr0.2FeO3 (LSF) or La0.8Sr0.2MnO3 (LSM) and were then calcined to either 1123 or 1373 K. The addition of dopants had little influence on the 1123-K composite electrodes but all dopants tested improved the performance of the 1373-K composites. With 1373-K, LSF-YSZ electrodes, the open-circuit impedances decreased dramatically following the addition of 10-wt%YSZ, 0.5-wt% Pd, 10-wt% Ce0.8Sm0.2O1.9 (SDC), 10-wt%CaO, and 10-wt% K2O. Similarly, the 1373-K, LSM-YSZ electrodes were enhanced by the addition of 10-wt% CeO2, 1-wt% Pd. and 10-wt% YSZ. Since the improved performance was close to that of the corresponding LSF-YSZ and LSM-YSZ electrodes that had been calcined to only 1123 K. it is suggested that the improved performance is related to structural changes in the electrode, rather than to improved catalytic properties or ionic conductivity.