Spinel and Perovskite Protection Layers Between Crofer22APU and La[sub 0.8]Sr[sub 0.2]FeO[sub 3] Cathode Materials for SOFC Interconnects

The interaction of the metallic interconnects with the cathode and the resulting time-dependent resistance of these material combinations is a major problem in solid oxide fuel cells (SOFCs). In this study, different conductive oxide coatings were used as protective layers to improve surface stability and electrical performance, as well as to mitigate or prevent chromium poisoning of the cells. Dense layers were obtained on the steel by electron-beam physical vapor deposition, by screen printing and by electroplating. The degradation of the interface between the coated Crofer22APU alloy and the (LSF) cathode was studied by resistance measurements in air at up to and analyzed by scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, and secondary ion mass spectrometry after exposure. measured the lowest resistance between the tested coatings. The highest resistance was found for , which also showed low protection against formation. exhibited the lowest resistance increase; however, this coating was not protective enough to prevent the formation of , especially during cyclic operation. Among the Mn–Co–Fe spinel compositions tested, the lowest resistivity values and the highest Cr retention were obtained with the spinel.