In-situ formed CuFe2O4 spinel coating by electroplating method for solid oxide fuel cell interconnect

A protective coating layer on chromium-containing interconnects is critical for preventing chromium diffusion and slowing the increase in area specific resistance (ASR) in solid oxide fuel cells (SOFC). In the present work, a stoichiometric CuFe2 alloy is successfully electroplated on the surface of SUS 430, and a CuFe2O4 spinel coating is formed through in-situ thermal oxidation. Density functional theory calculations and COMSOL simulations are employed to reveal the mechanism of CuFe2 alloy electroplating. The dense CuFe2O4 coating effectively blocks the outward volatile Cr species and suppresses the ASR increase in a long-term test (at 800 °C in the air for 1000 h). Furthermore, the practical application of CuFe2O4-coated SUS 430 is evaluated using a three-electrode cell, showing much improved durability due to the mitigated chromium poisoning. These results demonstrate that the CuFe2O4 coating significantly reduces the out-migration of Cr species from the interconnects. This work provides guidance on electroplating strategy for the future development of alloy coatings for SOFC interconnects.