High performance LaNi1-xCoxO_3-δ (x = 0.4 to 0.7) infiltrated oxygen electrodes for reversible solid oxide cells

Oxygen electrodes prepared by infiltration of yttria stabilized zirconia backbone with Ce_0.8Gd_0.2O_1.95 barrier layer and LaNi_1-xCo_xO_3-δ (x = 0.4 to 0.7) catalyst for application in reversible solid oxide cells have been studied. The effect of temperature and Ni:Co ratio on their phase composition, microstructure and electrochemical properties are discussed. It was shown that oxygen electrodes infiltrated with LaNi_0.5Co_0.5O_3-δ had the lowest polarization resistance, i.e. 67 mΩ cm² at 600 °C. The performance of a fuel electrode supported solid oxide cell with infiltrated oxygen electrode in both fuel cell and electrolysis mode was tested. Electrochemical characterization of the solid oxide cell showed that the resistance contribution from these oxygen electrodes to the overall cell resistance is minor i.e. approximately 20 mΩ cm² at a temperature of 700 °C. The cell was also tested in the steam electrolysis mode at a constant current of −1.0 A cm⁻² at 800 °C for 240 h. The oxygen electrode showed reasonable degradation rate with the oxygen electrode resistance of 33 mΩ cm² at 700 °C after 240 h of testing.