Perovskite-type oxides as oxygen electrodes for high temperature oxide fuel cells

Polarization and electrical conductivity measurements were made at 800°C in open air using the perovskite-type oxides La1−xSrxMO3 (M  Cr, Mn, Fe, Co) sputtered on ytteia stabilized zirconia electrolyte. The lowest cathodic polarization overpotential and the highest conductivity were obtained for the LaCoO3 electrode at 800°C. The overpotential varied depending on the pre-annealing temperature and period of the electrodes. At the annealing temperature of 800°C, the cathodic overpotentials for La1−xSrxCoO3 did not vary significantly with the annealing period, and at 1000°C increased with it. This increase of the overpotentials was interpreted in terms of a reaction between the electrolyte and the La1−xSrxCoO3 electrode. LaCoO3 and La0.7Sr0.3CoO3 reacted with the electrolyte to form La2Zr2O7 and Sr2ZrO4, respectively, at 1000°C. With La0.7Sr0.3MO3 (M  Cr, Mn, Fe), no reaction between the electrodes and the electrolyte was observed at 1000°C and Sr2ZrO4 was observed at 1100°C.