Effects of Impurities on the Degradation of SOFC Stacks

Effects of impurities on the degradation of SOFC components were examined at 5 different stacks. Several kinds of impurities (such as Na, Al, Si, P, S, Cr, and Sr) were detected at each component after long-term operation of stacks (2000-10000 hours operation). The concentration levels of impurities were analyzed at each cell component by secondary ion mass spectrometry (SIMS) in the order of magnitudes of ppm in weight. Several kinds of degradation phenomena were observed at cell components associated to impurities. Some degradation mechanisms were considered at the electrode/electrolyte interfaces.