CuMn1.8O4 protective coatings on metallic interconnects for prevention of Cr-poisoning in solid oxide fuel cells

Abstract Cr-poisoning of the cathodes due to the presence of metallic interconnects is detrimental to the performance of intermediate temperature solid oxide fuel cell stacks. Applying a protective coating on the interconnect is an effective solution to preventing Cr-poisoning. In this study, the application of a protective CuMn 1.8 O 4 spinel coating is explored. Dense coatings are deposited on both metallic flat plates and meshes by electrophoretic deposition followed by thermal densification steps. The coating is found to be a mixture of Mn 3 O 4 and cubic spinel phases at room temperature but is a pure cubic spinel phase between 750 °C and 850 °C. A reaction layer between the Cr 2 O 3 scale at the coating/interconnect interface and CuMn 1.8 O 4 coating is found to be a mixture of (Cu,Mn,Cr) 3-x O 4 cubic spinel phases with Cr-rich precipitates believed to be Cr 2 O 3 , indicating that the coating layer acts as a Cr getter. Solubility experiments show that 1 mol of the CuMn 1.8 O 4 phase can getter at least 1.83 mol of Cr 2 O 3 at 800 °C. Electrochemical testing of cells in the presence of coated interconnects show that the CuMn 1.8 O 4 coating getters Cr effectively for 12 days at 800 °C, leading to no performance loss of the cell due to Cr-poisoning.