Effects of high-valence Mo content on microstructure and properties of Ba₂Fe_2-xMo_xO_6- anode materials for solid oxide fuel cells

Double perovskites Ba2Fe2-xMoxO6-delta (BFMox, x = 1.0-0.3) were investigated as anodes of solid oxide fuel cells (SOFCs). In H-2, all the BFMox samples exhibit sufficient electrical conductivities (sigma > 2 S cm(-1)) at 600-800 degrees C. However, the BFMo0.7 and BFMo0.5 compositions exhibit relatively better redox stability than the others. Furthermore, using 250-mu m-thick La0.9Sr0.1Ga0.8Mg0.2O3-delta as electrolyte and Ba0.6Sr0.4Co0.9Nb0.1O3-delta as cathode(,) the BFMo0.7 and BFMo0.5 anode cells also show higher electrochemical performances with peak power density attaining 905 and 908 mW cm(-2), respectively, at 800 degrees C. Additi degrees nally, the BFMo0.7 and BFMo0.5 anodes show good electrochemical stability for long-term H-2 oxidation. However, the BFMo0.7 anode exhibits an especially high thermal expansion coefficient (TEC) similar to 61.9 x 10(-6) K-1 at 25-886 degrees C in air, nearly three times larger than that of the BFMo0.5 anode under the same condition (TEC=similar to 14.8 x10(-6) K-1). In view of this, the BFMo0.5 is considered to be a preferred anode candidate for SOFC.