Microstructures and Electrochemical Behavior of LSM Cathode with a Structured Electrolyte Modified by Flame Spraying

Abstract

Abstract Plasma-sprayed yttria-stabilized zirconia (YSZ) can be potentially employed as electrolyte coating in solid oxide fuel cells (SOFCs). The formation of a convex coating surface with semi-melted particles will increase the specific surface area and subsequently improve the output performance of SOFCs. However, using completely molten YSZ particles during plasma spraying leads to the formation of locally flat surface owing to the spreading of the liquid droplets on impact. In this study, flame spraying was employed to deposit YSZ particles on YSZ substrate using surface-melted particles. 4.5 mol% YSZ powder particles were used as spray materials. The deposition was carried out at different spray distances on the YSZ substrate preheated to 650 °C. The surface morphology of YSZ particles was characterized by SEM. The bonding of YSZ particles with the underlying YSZ substrate was examined from cross section. The electrochemical behavior of a single cell with a structured cathode was analyzed by electrochemical impedance spectroscopy. The results show that spray distance has significant influence on the morphology of deposited YSZ particles. The cathode polarization of a structured cathode was decreased by about 30% compared to a flat cathode.