Deposition mechanism of convex YSZ particles and effect of electrolyte/cathode interface structure on cathode performance of solid oxide fuel cell

A convex-structured electrolyte surface will lead to the formation of a high specific surface area which could be applied in many fields. Thermal spraying process is promising to fabricate such surface through particle deposition. However, the locally flat surfaces will be formed by using completely molten particles due to well spreading of liquid droplets on impact. In this study, a flame spraying method was employed to deposit convex yttria-stabilized zirconia (YSZ) particles on YSZ substrate for solid oxide fuel cell application. The convex structure was formed by the deposition of surface-melted particles, which were created due to the low particle temperature and velocity of the spray process. The effect of acetylene flow rate on the particle deposition behavior was examined. The surface morphology and surface area of YSZ particles were characterized by scanning electron microscope (SEM) and a 3D laser scanning microscope, respectively. The bonding between deposited YSZ particles and YSZ substrate was examined from cross section. The electrochemical behavior of single cell with the structured cathode was characterized by the electrochemical impedance spectroscopy. The results indicate that spray parameters have significant influence on the surface morphology of deposited YSZ particles and the surface area is increased up to a factor of 3.45. The cathode polarization with a structured cathode is approximately one-third of that with a flat cathode.