Electrodeposited Mn-Co Alloy Coatings for Solid Oxide Fuel Cell Interconnects

The operation of solid oxide fuel cells at temperatures of 650-850 °C has made it possible to replace the ceramic interconnects in fuel cell stacks with metallic interconnects comprised of chromia-forming ferritic stainless steels. However, chromia subscale growth and chromium evaporation reduce the interconnect conductivity and poison the cathode, causing unacceptable degradation in solid oxide fuel cell (SOFC) electrochemical performance. In order to eliminate the issues associated with chromium diffusion; this project will develop an electrically mediated electro-deposition process for depositing dense, crack-free manganese cobalt (Mn-Co) coatings onto the cathode side of SOFC interconnects. Following electro deposition, the Mn-Co alloy coating will be oxidized to form a (Mn, Co)3O4 spinel coating. In Phase I, small Crofer APU 22 and SS441 substrates will be coated and evaluated in terms of the coating thickness, uniformity, density, chemical composition, microstructure, and conductivity, using scanning electron microscopy with an energy dispersive X-ray analyzer and area-specific resistance measurements. Commercial Application and Other Benefits as described by the awardee: An inexpensive manufacturing process for conductive interconnect coatings should reduce the manufacturing costs of solid oxide fuel cells, bringing them one step closer to being a commercially viable alternative energy source. The realization of this energy source for stationary and distributive electric power stations could decrease the United States dependence on foreign oil and reduce emissions, such as SOx, NOx, and CO2 that negatively impact the environment.