Oxidation behaviors of the Sr2Fe1.5Mo0.5O6-δ-coated SUS430 metal interconnect in anode atmosphere for direct methanol solid oxide fuel cells

Abstract

The oxidation of metal interconnects on the anode side in solid oxide fuel cells (SOFCs) leads to the degradation of the electrical properties, which affects the performance and long-term durability of SOFC stacks. In this study, we explored the oxidation behaviors of the SUS430 alloy interconnect in methanol-water anode atmosphere and investigated the possibility of using Sr2Fe1.5Mo0.5O6-δ (SFM) perovskite materials as an oxidation-resistant coating on the anode side of the SUS430 alloy interconnect. The bare SUS430 alloy and the SUS430 alloy with SFM coating (thickness: ≈40 μm) were exposed in methanol/H2O anode atmosphere at 750 °C for 1000 h. After oxidation, a dense oxide scale with a thickness of 3.50 μm was formed on the surface of the bare SUS430 alloy; the area-specific resistance (ASR) of the alloy increased from 1.70 mΩ cm2 to 279.00 mΩ cm2. By contrast, the thickness of the oxide scale on the surface of SUS430 alloy with protective SFM coating under the same working condition was 0.70 μm; the ASR grows from 12.47 mΩ cm2 to 14.51 mΩ cm2. These results suggest that SFM forms an effective anode-side protective coating on the interconnects of SOFC stacks.