La0.4Sr0.6Ti1-xMnxO3-δ perovskites as anode materials for solid oxide fuel cells

Perovskite oxides, La0.4Sr0.6Ti1-xMnxO3-delta (x=0, 0.2, 0.4, 0.6), have been investigated in the search for new solid oxide fuel cell (SOFC) anode materials. La0.4Sr0.6Ti0.4Mn0.6O3-delta (LSTM4646) shows an electrical conductivity of 22.6 S/cm in air and 1.5 S/cm in wet Ar/4% H-2 [p(O-2)approximate to 10(-18) bar] at 810 degrees C. It is thermally and chemically compatible with yttria-stabilized zirconia (YSZ) electrolytes. Three processes govern the electrochemical performance of LSTM4646/YSZ anodes in wet Ar/H-2 or wet CH4. They are proposed to be charge transfer at the LSTM4646/YSZ interface, dissociative adsorption of hydrogen on the electrode surface, and gas conversion impedance, respectively. Due to the low polarization resistance of the LSTM4646/YSZ anode, 0.32 Omega cm(2), an electrolyte-supported H-2/air fuel cell with an LSM/YSZ cathode yields a power density of 365 mW cm(-2) at 0.7 V at 856 degrees C. In addition, this anode material is stable under a moderately humidified hydrogen atmosphere. It shows insignificant catalytic activity for the direct oxidation of methane however.