Real‐Time Analysis of Solid Oxide Electrolysis Cells Manufactured by Ceramic Sintering Process via Operando TEM and Electrochemical Impedance Spectroscopy

Solid oxide electrolysis cell (SOEC) degrades more rapidly than a solid oxide fuel cell. One of the primary causes of this degradation is interfacial issues between the electrode and electrolyte, such as the accumulation of oxygen ions and the lattice strain near the interface. Although extensive research has been conducted on these degradation mechanisms, most studies have relied on post-mortem microstructural analysis rather than real-time operando analysis, which limits the understanding of degradation mechanisms under real operating conditions. Additionally, while there are a few reports on operando studies using scanning transmission electron microscopy (STEM) on SOEC, comprehensive research that integrates these observations with mechanistic analysis is relatively limited. In this study, an advanced technique is applied to facilitate the identification of key degradation reactions through the correlation of electrochemical analysis with operando STEM using dense perovskite bulk electrodes. By simplifying electrode geometry and enabling quantitative impedance analysis, dense electrodes provide a clear framework for identifying interfacial and surface reactions. This methodology lays the groundwork for the real-time analysis of electrochemical properties and microstructural changes in dense bulk materials using impedance spectroscopy and STEM.