Mn[sub 1.5]Co[sub 1.5]O[sub 4] Spinel Protection Layers on Ferritic Stainless Steels for SOFC Interconnect Applications

In intermediate temperature solid oxide fuel cells (SOFCs), the use of cost-effective chromia-forming alloy interconnects such as ferritic stainless steels can lead to severe degradation in cell performance due to chromium migration into the cells at the cathode side. To protect cells from chromium poisoning and improve their performance, a spinel barrier layer has been developed and tested on the ferritic stainless steel Crofer22 APU. Thermal and electrical tests confirmed the effectiveness of the spinel protection layer as a means of stopping chromium migration and decreasing oxidation, while promoting electrical contact and minimizing cathode/interconnect interfacial resistance. The thermally grown spinel protection layer bonded well to the Crofer22 APU substrate and demonstrated stable performance under thermal cycling. © 2005 The Electrochemical Society. All rights reserved.