Effect of Preparation Methods on the Properties of Ni-YSZ Cermets for SOFC Anodes

Ceramic–metal composites (cermets) of yttria-stabilized zirconia, YSZ and Ni particles are largely utilized as the anode material in solid oxide fuel cells (SOFCs). In this work, three methods were applied to prepare Ni-YSZ cermets: NiO-coated YSZ, YSZ-coated NiO and mechanically mixed NiO-YSZ powders which were finally reduced by H2. The structure and sintering properties of the cermets were characterized using thermal gravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), transferring electron microscopy (TEM), energy dispersive spectroscopy (EDS) and 4-probe direct-current (4-DC) conductivity measurements, respectively. The crystalline of the cermets was identified to be the composite of cubic fluorite YSZ and cubic NiO structure. The NiO-coated YSZ cermet had the highest density and the lowest porosity. It also exhibited the highest electrical conductivity (e.g. 14,000 S/cm) at room temperature but the lowest ionic conductivity. LSSM-YSZ|YSZ|Ni-YSZ solid oxide fuel cells were prepared by a co-pressing method. The fuel cell made from the NiO-coated YSZ cermet exhibited the highest output performance with a maximum peak power density of 433 mW cm at 750°C and in H2/air atmosphere. This demonstrated the remarkable potential of NiO-coated YSZ cermets as the anode material for H2-fueled SOFCs.