The major degradation issues of solid oxide fuel cells (SOFC) are associated with the oxide scale growth and Cr evaporation of the metallic interconnect. To address these challenges, a highly dense spinel oxide coating was fabricated on a ferritic stainless steel interconnect using a cost-competitive ceramic processing route. The nano-scale Mn 1.5 Co 1.5 O 4 spinel powder was synthesized using a glycine-nitrate method, and the particle agglomerates were effectively disintegrated by a high-energy attrition milling process. The spinel protective coating, which was applied by screen printing, was sintered to a nearly full density, without causing damage to the metallic substrate, by a high-temperature annealing process in a reducing environment, followed by re-oxidation at a moderate temperature. The dense spinel coating remarkably reduced the growth rate of chromia scale and restrained the evaporation of chromium species, as verified by area specific resistance (ASR) measurements and analysis on chromium distribution over the cross-section. Strong adhesion between the coating and substrate was confirmed after 500-hour operation. The sintering mechanism involved in reduction-oxidation heat-treatment was studied based on dilatometry measurements and microstructural features. The implication of the ASR change and the chromium migration for stability of practical SOFC stacks was discussed in detail.

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A solid solution of ceria and zirconia is investigated as the ceramic component of the cermet anode for solid oxide fuel cells (SOFCs). Homogeneously dispersed NiO-Ce 0.75 Zr 0.25 O 2-δ (CZO) composite powder is synthesized via a single-step combustion process based on the glycine-nitrate method. The electrolyte-supported cell composed of a Ni -CZO anode, yttria-stabilized zirconia (YSZ) electrolyte and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF) -gadolinia-doped ceria (GDC) cathode is fabricated, and its electrochemical performance is compared with that of a reference cell employing the conventional Ni-YSZ anode. The Ni-CZO anode exhibits substantially higher performance than the Ni-YSZ anode, indicating that CZO actively participates in the anode's catalytic process, in contrast to YSZ. Impedance spectra of full-cells and half-cells are correlated to understand the electrode reaction mechanisms, and heavily overlapping impedance arcs are successfully deconvoluted using a differential relaxation time (DRT) technique. It is found that CZO promotes fuel oxidation through an oxygen spillover mechanism and enhances gas-solid interaction via H 2 adsorption on the ceramic component of the cermet anode, resulting in a reduction of the electrode polarization resistance. The potential of the Ni-CZO anode for practical applications and a strategy for further development are discussed in detail.