Preparation and Performance of MnLa_0.02Co_1.58Cu_0.4O₄ Spinel Coating on SOFC Metal Connector

During long-term high-temperature operation of solid oxide fuel cell（SOFC） stacks, battery performance degradation occurs due to high-temperature oxidation of SUS430（ferritic stainless steel） metallic interconnects and Cr volatilization-induced cathode poisoning. To address this problem, the Cu-La co-doped MnCo₂O₄ spinel powders were synthesized by a sol-gel method. A MnLa_0.02Co_1.58Cu_0.4O₄（MLCCu） spinel coating was deposited on SUS430 alloy through a dip-coating process, the effects of Cu-La co-doping on the coating’s oxidation resistance and electrical conductivity were systematically investigated. The results show that the MLCCu exhibits a single-phase spinel structure, Cu/La co-doping enhances the crystallinity of MLCCu powder and the thermal stability of the coating. The interface micro-morphology and cross-sectional elemental mapping reveal a 1 μm ultrathin Cr₂O₃ layer in MLCCu-coated alloy, demonstrating effective suppression of Cr diffusion and oxide layer growth. Compared with MC coated alloy samples, the MLCCu-coated alloy samples have lower oxidation rate, area-specific resistance and impedance activation energy. The synergistic effect of La and Cu doping significantly increases the density of Mn-Co spinel coating and improves the high temperature oxidation resistance and electrical conductivity of the alloy matrix.