Transition Metal Spinel Oxide Coatings for Reducing Chromium Poisoning in SOFCs

Abstract

A challenge in the long term operation of solid oxide fuel cells (SOFCs) is minimizing degradation due to chromium poisoning of the cathode. One approach is to apply a ceramic coating to the interconnect to minimize chromium volatilization and the associated detrimental effect on fuel cell performance. In this work the long-term stability of spinel oxide coatings for use in SOFCs has been evaluated. In particular, results on the interaction between chromia and the coating materials will be presented. To evaluate the impact of the reaction layer on cell performance, bulk analogues of the relevant composition have been prepared to allow for measurement of the relevant properties, such as electrical conductivity and coefficient of thermal expansion. The effect of changing the coating composition, in particular with the addition of iron or titanium, on the interaction and properties has also been evaluated. The results indicate that the performance of manganese cobalt oxide coatings can be improved with the addition of iron or titanium.