Development of ScSZ electrolyte fabricated by very low pressure plasma spraying for metal supported SOFCs applications

Very low pressure plasma spraying is an attractive method which can significantly avoid the oxidation of metal substrate. In this study, both anode and electrolyte was fabricated by VLPPS method. To investigate the microstructure of ScSZ, the spraying distance of electrolyte was set to 150, 250, 350 mm. The fragile cross microstructure suggests that typical lamellar structure is replaced by trans-granular structure though in a relatively low temperature (<350 °C). The apparent porosity of ScSZ coatings is 4.75 - 6.83 % using image analysis method. The ionic conductivity of sprayed coatings at 250 mm spraying distance can reach 0.068 S·cm^-1 at 750°C, ~ 68 % standard of bulk material. The average specific surface area of ScSZ coatings top surface can reach 6.53 to 8.30 measured by a 3D confocal laser microscope. Finally, testing cells based on very low pressure plasma sprayed ScSZ electrolyte membranes shows a maximum output power density of 1111.6 mW·cm^-2 and an OCV of 1.07 V at 750 °C.The ohmic resistance of whole cell is 0.1 Ω·cm² and the total resistance of whole cell is 0.15 Ω·cm², suggesting that low-pressure plasma spraying is a promising approach for manufacturing of high-performance MS-SOFCs.