Calcium stabilized La0.6Sr0.4Fe0.8Mn0.2O3-δ perovskite as ceramic fuel electrode for solid oxide cell

Abstract

As a potential fuel electrode for solid oxide cells, La0.6Sr0.4Fe0.8Mn0.2O3-δ perovskite suffers from phase decomposition in reducing atmosphere at operational temperature. In this work, Ca is introduced to its A-site to stabilize the perovskite structure. While doping Ca is demonstrated to be achievable in the full compositional range, only La0.6Sr0.1Ca0.3Fe0.8Mn0.2O3-δ is stable in hydrogen atmosphere at 800 °C. The doping improves the thermal expansion compatibility with electrolyte, increases the oxygen vacancy concentration and content of adsorbed oxygen species, but reduces the electronic conductivity. Meanwhile, the doping increases the electrochemical performance as the fuel electrode, such as reduces the interfacial polarization resistance by 38% to 0.13 Ω cm2 at 800 °C, increases the peak power density by 17% to 1.05 W cm−2 at 800 °C when operated in fuel cell mode with humidified hydrogen as the fuel, and shows a high current density of 1.89 A⋅ cm−2 at 800 °C when evaluated in electrolysis cell mode to electrolyze pure CO2. Overall, doping Ca not only prevents the possible phase transition but also improves the catalytic activity as fuel electrode for solid oxide cells.