Increased Anodic Performance of La0.5Sr0.5Mn0.9Al0.1O3 by Doping with Co for Solid Oxide Fuel Cells Using Dry C3H8 Fuel

Abstract

Effects of Co and Al co-doping to La0.5Sr0.5MnO3 (LSM55) for anode were studied and it was found that doping Co for Mn site is effective for decreasing anodic IR loss leading to increased power density. XRD measurement suggests that Co substituted Mn site over wide composition range and up to 40 mol% partial substitution of Co in LaMnO3 structure was successfully performed. The maximum power density was increased by doping Co for LSM doped with 10 mol% Al for both H2 and C3H8 fuel. In particular, the smallest IR loss and anodic overpotential were achieved when 20 mol% Co was co-doped. The maximum power density of the cell using La0.5Sr0.5Mn0.7Al0.1Co0.2O3 was achieved at 953 and 246 mW/cm2 for H2 and C3H8 fuel at 1273 and 1173 K, respectively. Increase in power density can be assigned to the increased surface activity to the electrochemical oxidation by doping Co. Although stability of LSM perovskite structure is still insufficient in dry C3H8 atmosphere, doping Al is effective for increasing stability and so co-doping Al and Co to Mn site of LaMnO3 is effective for decreasing anodic overpotential for direct C3H8 type SOFC.