Microstructures and Interfacial Resistance of LSM-SDC Composite Cathodes for IT-SOFCs

Microstructures, interfacial resistances, and activation energy of the symmetrical composite cathodes [50wt%(La0.85Sr0.15)0.9MnO3-δ(LSM)+50wt% Sm0.2Ce0.8O1.90] were studied for intermediate temperature (550-800℃) solid oxide fuel cells (IT-SOFCs) based on Sm0.2Ce0.8O1.90 (SDC) electrolytes. The optimum sintering temperatures for LSM+GNP-SDC and LSM+OCP-SDC composite cathodes are 1200℃and 1250℃, respectively. The interfacial resistances at 800℃are 0.78 and 0.35Ω·cm2, respectively, for LSM+GNP-SDC and LSM+OCP-SDC, as determined using AC impedance spectroscopy. The electrical conductivity of composite electrodes depends on the electrodes microstructures, which are greatly influenced by starting powder characteristics and sintering temperatures.