Ti-doped Sr2Fe1.4-xTixMo0.6O6-δ double perovskites with improved stability as anode materials for Solid Oxide Fuel Cells

Abstract Ti-doped Sr2Fe1.4-xTixMo0.6O6-δ perovskites with improved redox stability are systematically investigated as anode materials for Solid Oxide Fuel Cells. Materials are characterized in terms of their crystal structure, thermal expansion coefficient, oxygen content, transport properties, chemical stability and compatibility with electrolyte, as well as electrochemical performance. Partial substitution of Fe with Ti in Sr2Fe1.4-xTixMo0.6O6-δ changes crystal structure with B-site ongoing disordering. Ti-doping enhances stability of materials in air, but decreases the conductivity. Thermal expansion coefficients of Sr2Fe1.4-xTixMo0.6O6-δ in air are moderate below 600 °C, however, an appearance of SrMoO4 at higher temperatures limits their exposure to air. Sr2Fe1.4-xTixMo0.6O6-δ (x = 0, 0.1) oxides show very high conductivity in 5 vol.% H2/argon. The constructed SOFC with Sr2Fe1.3Ti0.1Mo0.6O6-δ anode delivers very good power density exceeding 0.64 W cm2 at 900 °C in humidified H2. A small total electrode polarization resistance (RHF + RLF) is measured, equal to 0.18 Ω cm2 at 900 °C.