CuFe2O4 nano-spherical powder directly served as interconnect coating for solid oxide fuel cells applications

In order to mitigate the detrimental effect of cathode poisoning induced by Cr in solid oxide fuel cell (SOFC) metallic interconnects, a potential remedial strategy is to deposit spinel coatings on the surface of the steel for protective purposes. However, powder-based deposition methods typically require post-treatment at high temperature, which causes severe oxidation reaction and is detrimental to mechanical properties. In this study, a novel approach is introduced: using a nano-spherical CuFe2O4 spinel powder as a direct coating. Thanks to its excellent sintering ability, this coating can be applied directly under SOFC working conditions without additional heat treatment. Characterization techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) confirmed the cubic crystalline phase and nano-spherical morphology of CuFe2O4 powder synthesized via the solvothermal method. Importantly, this powder displayed enhanced sintering capability, reducing the sintering temperature approximately to SOFC operational temperature. When applied as a protective coating for SUS 430 interconnects, the CuFe2O4 spinel nano-spherical powder demonstrated remarkable effects, including reduced alloy oxidation, mitigated increase in area specific resistance (ASR), and effective prevention of chromium outward diffusion. As a result, the service life of the SOFC single cell in contact with the CuFe2O4 spinel nano-spherical powder-coated interconnect was significantly prolonged. [Display omitted] •A special CuFe2O4 nano-spherical powder was successfully prepared.•Nano-spherical CuFe2O4 powder as a direct coating for SOFC interconnect.•The dense protective coating prevents the interconnect from oxidizing.•The coating effectively alleviates chromium poisoning in the cathode.•This work provides a new idea of coatings for metallic interconnect.