Co3O4/Sm-Doped CeO2/Co3O4 Trilayer Coating on AISI 441 Interconnect for Solid Oxide Fuel Cells.

In this work, a novel Co/Sm-doped CeO2 (SDC)/Co trilayer of ∼6 μm is deposited by alternating electrodeposition and electrophoresis and oxidized to a Co3O4/SDC/Co3O4 trilayer structure. This coating is unique and effective in the following aspects: (1) The area specific resistance of the coated interconnect is more stable and lower than that of the uncoated interconnect after thermal treatment at 800 °C for 400 h. (2) The Co3O4/SDC/Co3O4 coating layer can effectively inhibit Cr diffusion and evaporation and significantly slow the oxidation rate of the interconnect. (3) The Sm0.5Sr0.5Co0.2Fe0.8O3 cathode in the electrolyte/cathode/interconnect half-cell retains its initial stoichiometry after 100 h of the thermal treatment. Subsequently, the ohmic resistance RΩ, high frequency polarization resistance RH, and low frequency polarization resistance RL of the half-cell with the Co3O4/SDC/Co3O4 coated interconnect are all smaller than those of the half-cell with the bare interconnect. The Co3O4/SDC/Co3O4 coating layer has great advantages to be used as a protective layer for the metallic interconnect in solid oxide fuel cells to improve cell performance, stability, and durability.