Direct utilization of hydrocarbon for Solid Oxide Fuel Cells (SOFCs) using oxide ion conductor have the advantage of cost, high energy conversion efficiency and expanding the application area of SOFC. By eliminating the initial external reforming process of hydrocarbon fuels to syngas, significant advantages in cost and simplicity of gas handling process can be expected. Theoretically, direct utilisation of hydrocarbon for fuel is possible in SOFC using oxide ion conducting electrolyte, however, this is usually not easy when the conventional Ni base metal is used for anode because the formation of carbon is significantly occurred resulting in the deactivation of anode, or in the most serious case, permanent failure of the cell is occurred. Even methane as fuel, thermodynamic calculations predict that carbon will form at 1073 K unless steam is co-fed.

In this study, Co and Al co-doping to La_0.5Sr_0.5MnO₃ (LSM55) for anode were studied and it was found that doping Co is effective for decreasing anodic IR loss and the power density could be much increased by doping Co for Mn site of LSM doped with Al. XRD measurement suggests that Co was substituted Mn site over wide composition range and up to 40 mol%, partial substitution of Co to Mn in LaMnO₃ structure was successfully performed. It was found that 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 doped. The maximum power density of the cell using La_0.5Sr_0.5Mn_0.7Al_0.1Co_0.2O₃ was achieved 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.

Mixing oxide ion conductor to Co and Al doped LaMnO₃ anode was further studied for increasing power density. Among the examined mixed conductor, it was found that mixing Sm doped CeO₂ is effective for increasing power density and the MPD of 850 mW/cm² was achieved at 1173 K on 20 wt% SDC mixed with Co and Al doped LSM anode.