Evaluation of Ag-doped (MnCo)₃O₄ spinel as a solid oxide fuel cell metallic interconnect coating material

To suppress vaporization of Cr oxides from the metallic interconnects of solid oxide fuel cells, studies on ceramic coating materials have been widely conducted. Among the studied materials, Mn-Co spinel has been a point of focus because of its benign reaction with metal substrates. This paper presents the evaluation results for a modified Mn-Co spinel. Ag was selected as a dopant for Mn-Co spinel, and various experiments were carried out to investigate the suitability of the doped spinel as an interconnect coating material. First, the lattice parameters were demonstrated to be stably maintained even though the Ag dopant is a precious metal. Second, the electrical conductivity was confirmed to be increased upon doping, and the thermal expansion coefficient of the doped material well matched that of AISI444. Third, through long-term oxidation and single-cell tests, the Ag-doped Mn-Co spinel was shown to be a useful coating material for compatible metallic interconnects in solid oxide fuel cell cathodes.