Phase Stability of Perovskite Oxide Electrodes under Operating Condition in Solid Oxide Fuel Cell

Perovskite-based materials are typically used as electrodes in solid oxide cells (SOCs) owing to their high catalytic activity in oxygen exchange reactions. The degradation of typical SOCs is a well-known phenomenon that is primarily attributed to the A-site cation redistribution within perovskite-based electrodes at elevated operating temperatures. To date, investigations of the degradation and stability of perovskite electrodes have predominantly focused on assessing thin-film electrodes under an open-circuit voltage. This study proposes a detailed degradation mechanism of electrodes based on bulk-dense materials under the operating conditions of an actual solid oxide fuel cell. Our findings revealed that La0.6Sr0.4Co0.2Fe0.8O3–δ is decomposed into SrO, spinel phase ((CoFe)3O4), and La-rich perovskite in the subsurface region under cathodic bias conditions. Additionally, the results of this study indicate that the phase decomposition associated with elements in the B-site must be considered to improve the enhancement of the stability and oxygen reduction reaction activity.