Development of new fast oxide ion conductor and application for intermediate temperature Solid Oxide Fuel Cells

Solid Oxide Fuel Cell (SOFC) show great promise as new power generators with high efficiency. Decreasing the operating temperature is critically required for the further development of SOFC. This review introduces that oxide ion conductivity in the perovskite oxide of LaGaO ₃, which was found by our group. LaGaO ₃ doped with La and Mg exhibits the high oxide ion conductivity over a wide P _O2 range; the value is higher than that of Y ₂O ₃-stabilized ZrO ₂ by an order of magnitude. When LaGaO ₃-based oxide was used as the electrolyte of SOFC, the power density could be improved greatly, in particular over the low-temperature range. In this study, the power generating property of LSGM using a thin film of LaGaO ₃ is also introduced. The maximum power density of the cell using LaGaO ₃-based oxide is as high as 0.6 W cm ^-2 at 773 K. This suggests that SOFC could be operable at temperature lower than 773 K.