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.