CHAPTER 5: Interconnect Materials for SOFC Stacks
Published:16 Aug 2013
Interconnects are one of the most challenging materials issues for solid oxide fuel cell (SOFC) stacks. They are exposed to both oxidizing conditions at the cathode and reducing conditions at the anode, at elevated temperatures, and must maintain good conductivity and good mechanical stability. Both ceramic and metallic interconnects have been used extensively for different working temperatures. Ceramic perovskite (ABO3) interconnects, which typically are used in the higher temperature ranges (900–1000 °C), dopant elements and concentrations at both A and B sites can be altered to control properties of electronic conductivity, thermal expansion coefficient (TEC), and stability. Metallic interconnects can be used at lower temperatures (typically 400–800 °C), are potentially much lower in cost, and are more mechanically stable in the typical temperature range of use. Because of the cost advantage, we will focus the metallic interconnect materials and on issues such as materials selection from various alloys, challenges for metallic materials, and how to handle them, more specifically, various coatings to suppress scale growth and Cr poisoning effect. (Mn,Co)3O4 spinel coatings are the most promising coatings to meet the application requirements. Furthermore, for both ceramic and metallic interconnect materials, designs and applications from industrial teams are reviewed.