Kinetic Mechanism That Influence the Electrochemical Behaviour of Different Type of Cathodic Materials for Intermediate Temperature Solid Oxide Fuel Cells

Since long time perovskite-type cathodic materials have attracted attention as cathodes for intermediate-temperature solid oxide fuel cells (500-700 °C), because of the high catalytic activity for oxygen reduction reaction. However, a delicate match between high electrocatalytic activity and long lasting electrochemical and structural properties is still an open issue for good performing SOFCs electrodes and cells. The study presented in this paper will analyse the results obtained on this field by the authors since several years of research activity considering three types of basic materials (La0.8Sr0.2MnO3-δ –LSM, La0.6Sr0.4Co0.2Fe0.8O3-δ –LSCF, and Ba0.5Sr0.5Co0.8Fe0.2O3-δ -BSCF) in different electrode configurations; pure materials, composite and impregnated electrode formulations. The aim of this research is to elucidate how the intrinsic material properties can affect the kinetic rate determining step within the complex overall reaction mechanism of oxygen reduction. The evidence of these phenomena is highlighted through the electrochemical response of the considered systems operating under different conditions determined by applied overpotentials, reactant partial pressures and temperatures.