Scandia-stabilized zirconia electrolyte with improved interlamellar bonding by high-velocity plasma spraying for high performance solid oxide fuel cells

Abstract

A main challenge of conventional atmospheric plasma spraying (APS) in the application for SOFCs is how to fabricate the dense electrolyte which can be used directly. In this study, supersonic atmospheric plasma spraying (SAPS), one of the high-velocity plasma spraying technologies, was used to prepare scandia-stabilized zirconia (ScSZ) electrolyte to enhance the performance of SOFCs by decreasing the porosity and improving the ionic conductivity with the continuous growth of columnar grains across splat interfaces. The temperature and velocity of in-flight ScSZ particles were measured, and the influences of deposition temperature on the microstructure and cell output performance were investigated. Results showed that the as-sprayed ScSZ prepared by SAPS exhibited higher gas tightness than conventional APS by approximately one order of magnitude. With the increase of deposition temperature from 200 °C to 600 °C, the microstructure of ScSZ electrolyte changed from the traditional lamellar structure with limited interface bonding to the long columnar crystal structure, and the maximum output power densities of the cells with 60 μm ScSZ electrolyte prepared by SAPS increased by more than 70% with the increase of deposition temperature from 200 °C to 600 °C and reached 995 mW cm−2 at 1000 °C.