| Abstract
| - The formation of insulating phases at the interface between cathode and electrolytematerials during solid oxide fuel cell (SOFC) operation leads to deleterious effects on SOFCproperties. We report in situ impedance spectroscopy measurements of the degradationprocess of porous La0.65Sr0.35MnO3/Zr0.84Y0.16O1.92 electrodes submitted to annealing temperatures above normal SOFC operating temperature, which is around 1173 K, simulating long-term SOFC operation. To measure the remaining effects after high-temperature annealing,impedance diagrams were plotted during the entire heating process up to the annealingtemperatures, and during the complete cooling process. These diagrams were also plottedduring the aging periods to follow the overall degradation. It was possible to detect andquantify electrical and electrochemical degradations, which are related to the formation ofinsulating phases at the electrode/electrolyte interface. Samples were annealed for about200 h in air at temperatures between 1373 and 1673 K. Scanning electron microscopy andenergy-dispersive X-ray spectrometry were also used to detect microstructural changes atthe electrode.
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