Mechanistic Study on the Corrosion of (La,Sr)(Co,Fe)O 3-δ Cathodes Induced by CO 2 .

Solid Oxide Fuel Cell (SOFC) cathodes operating in ambient atmospheric conditions inevitably encounter CO 2 contamination, leading to sustained performance deterioration. In this investigation, we examined the impact of CO 2 on three variants of (La,Sr)(Co,Fe)O 3-δ cathodes and employed the distribution of relaxation times method to distinguish distinct electrochemical processes based on impedance spectra analysis. We meticulously analyzed and discussed the corrosion resistance of these (La,Sr)(Co,Fe)O 3-δ cathodes under high CO 2 concentrations, relying on the experimental data. Electrochemical impedance spectroscopy results revealed that La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF-6428), La 0.4 Sr 0.6 Co 0.2 Fe 0.8 O 3-δ (LSCF-4628), and La 0.4 Sr 0.6 Co 0.2 Fe 0.7 Nb 0.1 O 3-δ (LSCFN-46271) cathodes exhibited persistent degradation when exposed to CO 2 at temperatures of 650 °C or 800 °C during the durability-testing period. An increase in electrode polarization resistance was observed upon CO 2 introduction to the electrode, but electrode performance recovered upon returning to a pure air environment. Furthermore, X-ray diffraction and scanning electron microscopy analyses confirmed that CO 2 did not cause permanent damage to the (La,Sr)(Co,Fe)O 3-δ cathodes. These findings indicate that the (La,Sr)(Co,Fe)O 3-δ cathodes exhibit excellent resistance to CO 2 -induced corrosion.