Microstructure of Ni/YSZ cermets according to particle size of precursor powders and their anodic performances in SOFC

Four different Ni/YSZ cermets were prepared by combining two sets of NiO and YSZ powders of different size. The microstructural change evolved during the course of electrode adhesion and cell operation was monitored using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The anodic activity was compared by analyzing the ∝ impedance spectra of four Ni/YSZ cermet (H₂) / YSZ half cells at 1000 °C. Among the cermets, the one that prepared from the smaller NiO and larger YSZ powder showed the best anodic performances on aspects of the initial activity and long-term stability. This favorable performance is partly responsible to the presence of larger YSZ particles which provide a supporting matrix to suppress the microstructural change against Ni sintering and concomitant volume shrinkage, and partly to an easy formation of Ni channel for electronic conduction. Anodic performances of the other cermets were also discussed based on their microstructure.