Ce-doped (Mn,Co)3O4 coatings for solid oxide fuel cell interconnect applications

Abstract

In order to improve the electrical conductivity of solid oxide fuel cell (SOFC) interconnect coatings, a series of Ce-doped (Mn,Co)3O4 (Mn1.5-xCo1.5-xCe2xO4+δ, x = 0, 0.025, 0.05, and 0.1) coatings are prepared. The chemical composition, lattice structures, morphology, electrical properties, and weight gain of the coatings are characterized. Experimental results show that doping Ce lowers the area-specific resistance of (Mn,Co)3O4 coatings from 6.83 to 2.62 mΩ cm2 at 800 °C. The electrical conductivity improvement can be attributed to the ion substitution by Ce3+ that turns (Mn,Co)3O4 into (Mn,Co)2CeO4, an N-type semiconductor with a higher electrical carrier density. However, the coatings with heavier doping of Ce exhibit more structural defects due to the lattice parameter reduction and volume shrinkage, which weaken the oxidation resistance of the coatings. This study verifies that doping Ce can effectively improve the electrical conductivity of spinel coatings. The negative influence of doping Ce can be mitigated by modifying the coating preparation technique or by changing the SOFC operating temperature.