Interconnect Development for Solid Oxide Fuel Cell Application

Abstract

Solid oxide fuel cell (SOFC) is a green and reliable alternative energy source. Recent developments in SOFC have reduced its operating temperature from high (>1000 °C) to intermediate (<800 °C), thereby replacing ceramics by metal alloys as interconnect materials. Strict criteria in selecting interconnect material lead to Cr-based alloys as potential candidates, especially ferritic stainless steel (Fe-Cr-). Fe-Cr- possesses electrical conductivity, malleability, and low cost but it undergoes fast chromia scale growth rate, which leads to gaseous Cr species migration when exposed to high temperature (>800 °C); the gas will cause poisoning on cathode, leading to cell degradation. To overcome this issue, protective coating is used as a barrier to prevent the gaseous Cr species from surfacing. Among the coatings that have been used in previous studies, spinel coating, especially (Mn, Co)3O4, exhibits the best performance in terms of coefficient of thermal expansion (CTE) and area specific resistance in long SOFC operation. A dopant, such as Cu, is added into the Mn–Co composition to improve the electrical conductivity and CTE of the coating.