Catalyst-infiltrated supporting cathode for thin-film SOFCs

The fabrication and electrochemical performance of co-fired, LSM–SYSZ [i.e. La0.65Sr0.30MnO3 (LSM)–(Sc2O3)0.1(Y2O3)0.01(ZrO2)0.89] supported thin-film cells were examined using humidified hydrogen as a fuel. Co-firing of bilayers and trilayers was successful at 1250 °C by optimizing the amount of carbon pore formers. A power density of a factor of 2.5 higher than that recently reported for the same type of cell at 800 °C [H. Ohrui, K. Watanabe, M. Arakawa, J. Power Sources, 112, 90 (2002)] was obtained for a cell with cobalt infiltration into the supporting cathode: the peak power densities were 455, 389, 285, 202, 141 mW/cm2 at 800, 750, 700, 650, 600 °C, respectively, and in most cases power densities at 0.7 V exceeded more than 90% of the peak output. Increasing the cathode porosity from 43% to 53% improved peak power densities by as much as 1.3, shifting the diffusion limitation to high current densities. Cobalt infiltration into the support improved those by as much as a factor of 2 due to a significant reduction in nonohmic resistance. These results demonstrate that cobalt catalyst-infiltrated LSM can be effective and low-cost supporting electrodes for reduced temperature thin film solid oxide fuel cells (SOFCs).