Densification of Plasma-Sprayed YSZ Electrolyte by Suction Filtration Using Submicron/Nanoparticle Suspension for Metal-Supported SOFCs

Abstract

Atmospheric plasma spraying (APS) is widely used for the fabrication of metal-supported solid oxide fuel cells (MS-SOFCs) due to its cost-effective and fast process. However, the incomplete melting of partial electrolyte particles in the layer-by-layer deposition process leads to a relatively porous electrolyte layer, which causes severe gas leakage and hinders its implementation on MS-SOFCs. In this study, a simple and efficient two-step method is developed to achieve the densification of a plasma-sprayed YSZ electrolyte layer in a tubular MS-SOFC through suction filtration using a YSZ submicron/nanoparticle suspension. The prepared tubular MS-SOFCs were immersed in the YSZ submicron-particle suspension, and the pressure inside the tubular SOFC was reduced to -20 kPa to drive the YSZ submicron particles to fill the pores in the YSZ electrolyte. After suction filtration for 1 h, the gas permeability of the YSZ electrolyte decreased from 2.57×10-5 to 5.84×10-6 by a factor of 4.4, and the pores in the YSZ electrolyte decreased from the micron scale to the submicron scale. Further densification can be achieved by a second suction filtration treatment in the YSZ nanoparticle suspension so that the pores can be further decreased from the submicron scale to the nanoscale, which ensures gas tightness and can be used as the electrolyte of MS-SOFCs.