Electrophoretic Deposition of Protective Spinel Coatings for Solid Oxide Cell Interconnects – Towards Stack Integration

We evaluated electrophoretic deposition (EPD) of spinel coatings for solid oxide cell (SOC) interconnects with a focus on stack integration. Two compositions, MnCo 1.9 Fe 0.1 O 4 (MCF) and CuMn 1.8 Ni 0.2 O 4 (CMN), were deposited from water/ethanol suspensions and subjected to three thermal routes: direct oxidation and two-step treatments with reduction in Ar/H 2 at 900 or 1000 °C followed by oxidation. Structural evolution, chromium evaporation, mass gain, and ex situ area-specific resistance (ASR) were assessed. Sealant compatibility with a Ca-Ba-silicate glass and applicability to representative flow-field geometries were investigated. All coatings formed continuous layers; two-step treatments enhanced densification compared to direct oxidation. Prereduction of MCF layers at 1000 °C yielded the lowest Cr evaporation and mass gain, whereas CMN exhibited chromium ingress, phase variations, and coarsened microstructures. ASR values for all types remained around or below 20 mΩ cm 2 . Glass-joining produced dense composites; limited cation diffusion was observed for MCF, while CMN showed substantial Cu penetration into the glass. EPD produced uniform, defect-free coatings on complex flow-field structures, with only slight thickness variations across the profile. These results support MCF-EPD with a 1000 °C reduction step and in situ oxidation during stack assembly as a process-compatible route for protective interconnect coatings in high-temperature SOCs, while CMN remains of particular interest for intermediate-temperature applications.