The effects of minor elements in La sub(0.6)Sr sub(0.4)Co sub(0.2)Fe sub(0.8)O sub(3-[delta]) cathodes on oxygen reduction reaction

It is known that the minor elements affect the performance of solid oxide fuel cell (SOFC). In this study, we focus on the influence of minor elements on the SOFC cathode properties. The Ca, Ba, Al, and Si, which originate from raw materials and production processes for SOFC cathodes, are investigated as minor elements that may have effect on the properties of La sub(0.6)Sr sub(0.4)Co sub(0.2)Fe sub(0.8)O sub(3-[delta]) (LSCF) cathode. To examine the effects of minor elements on the cathode properties, Ca, Ba, Al, and Si with a controlled concentration are added to the LSCF reference sample. Conductivity relaxation measurements are conducted to determine the chemical diffusion coefficient (D sub(chem)) and surface exchange coefficient (k sub(tr)), which governs the overpotential characteristics of the LSCF cathode. The results show that Al and Si have negative effects on both D sub(chem) and k sub(tr) while Ca and Ba do not alter D sub(chem) and show weakly positive effects on k sub(tr). The effects of Ca and Ba for the cathode properties are discussed on the basis of XPS measurements.