Journal of Power Sources, Vol.277, 44-51, 2015
The effects of minor elements in La0.6Sr0.4Co0.2Fe0.8O3-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(0.6)Sr(0.4)Co(0.2)Fe(0.8)o(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-chem) and surface exchange coefficient (k(tr)), which governs the overpotential characteristics of the LSCF cathode. The results show that Al and Si have negative effects on both D-chem and k(tr) while Ca and Ba do not alter D-chem and show weakly positive effects on k(tr). The effects of Ca and Ba for the cathode properties are discussed on the basis of XPS measurements. (C) 2014 Elsevier B.V. All rights reserved.
Keywords:Solid oxide fuel cell;Minor elements;Cathode;Conductivity relaxation method;Surface exchange coefficient;X-ray photoelectron spectroscopy