Effect of composition of NiO/YSZ anode on the polarization characteristics of SOFC fabricated by atmospheric plasma spraying

Atmospheric plasma spraying is regarded as one of the most promising processing methods for the production of solid oxide fuel cells (SOFCs) because of its fast deposition rate and cost-effective characteristic compared with other film formation processes. Thermally sprayed ceramic deposits are characterized by lamellar structure resulting from the insufficient filling and incomplete wetting of molten liquid on previously formed rough coating surfaces. There are large voids (especially larger than 10 μm), nonbonded interface, and vertical cracks (in particular, in individual ceramic lamella which are in the submicrometer size range). The bonding at the interface between flattened particles is much less than the apparent total interface area. The microstructure of plasma-sprayed coating can be significantly influenced by the feedstock. In this paper, a Ni-Al₂O₃ cermet supported tubular SOFC cell with three different anodes was fabricated by thermal spraying. The effect of the anode microstructure on the performance of SOFC was investigated. The influence of the anode structure on the electrode polarization was examined. The results showed that the maximum output power density strongly depends on the anode microstructure. The length of the triple-phase boundaries (TPBs) can be increased by decreasing the particle size of YSZ and Ni in composite anode.