Mechanistic Study on the Corrosion of (La,Sr)(Co,Fe)O_3- Cathodes Induced by CO₂

Solid Oxide Fuel Cell (SOFC) cathodes operating in ambient atmospheric conditions inevitably encounter CO2 contamination, leading to sustained performance deterioration. In this investigation, we examined the impact of CO2 on three variants of (La,Sr)(Co,Fe)O3-delta 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)O3-delta cathodes under high CO2 concentrations, relying on the experimental data. Electrochemical impedance spectroscopy results revealed that La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF-6428), La0.4Sr0.6Co0.2Fe0.8O3-delta (LSCF-4628), and La0.4Sr0.6Co0.2Fe0.7Nb0.1O3-delta (LSCFN-46271) cathodes exhibited persistent degradation when exposed to CO2 at temperatures of 650 degrees C or 800 degrees C during the durability-testing period. An increase in electrode polarization resistance was observed upon CO2 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 CO2 did not cause permanent damage to the (La,Sr)(Co,Fe)O3-delta cathodes. These findings indicate that the (La,Sr)(Co,Fe)O3-delta cathodes exhibit excellent resistance to CO2-induced corrosion.