Fe-substituted SrTiO3−δ–Ce0.9Gd0.1O2 composite anodes for solid oxide fuel cells

A new composite solid oxide fuel cell anode material, SrTi1−xFexO3−δ mixed with Gd-doped ceria, was tested in La0.9Sr0.1Ga0.8Mg0.2O3−δ electrolyte-supported cells with La0.4Ce0.6O2 barrier layers and La0.6Sr0.4Fe0.8Co0.2O3 cathodes. The x = 0.7 composition had an anode polarization resistance of 0.17 Ω cm2, at 800 °C in humidified H2, much lower than the value 0.39 Ω cm2 measured for x = 0.4 and 3.14 Ω cm2 for x = 0. The reduced polarization resistance correlated with increased oxygen non-stoichiometry δ, which suggests that it may be related to increased ionic conductivity. Electrochemical impedance spectroscopy (EIS) measurements at 800 °C on the x = 0.7 anode cell showed a main response centered at ∼1 Hz that increased with decreasing hydrogen partial pressure. The maximum power density observed was for the x = 0.7 cell – 337 mW cm−2 at 800 °C in air and humidified hydrogen – and was limited mainly by the thick electrolyte.