Electrochemical performance and degradation of (La0.6Sr0.4)0.99CoO3 − δ as porous SOFC-cathode

This paper shows that measured impedance in porous (La0.6Sr0.4)0.99CoO3 − δ cathodes can be dependent on both gas diffusion and electrode kinetics at temperatures above 700 °C or below ambient pO2s if electrode kinetics are fast. The reaction mechanism is discussed on the basis of measured temperature- and pO2-dependences. The degradation was found to be related exclusively to the electrode kinetics and measured about 0.5–1.5 mΩ cm2 days− 1 depending on temperature with a higher rate measured in moisturised air. We speculate on degradation mechanism that involves formation of strontium hydroxides at catalytically active oxygen vacancy sites at the electrode surface.