Performance of YSZ electrolyte layer deposited by atmospheric plasma spraying for cermet-supported tubular SOFC

Yttria-stabilized zirconia (YSZ) was deposited by plasma spraying to develop a cost-effective processing method for the fabrication of electrolyte layer in solid oxide fuel cells (SOFCs). A densification process to plasma-sprayed YSZ coating was conducted with the aim of achieving a dense coating of necessary gas-tightness and an improved ionic conductivity. The densification of ZrO₂-4.5mol% Y₂O₃ electrolyte, which was produced by atmospheric plasma spray, was performed by impregnating yttrium and zirconium nitrate solution into the coating followed by heat-treatment. The results show that the YSZ layer of the gas permeability comparable to that of fully sintered one can be formed through plasma spraying followed by impregnation densification. The test cell yielded an OCV of 1.04V and a maximum output power density of 101mW/cm² at 930°C. Those results show that the combination of plasma spraying with post-impregnation is a feasible process to fabricate YSZ electrolyte layer used in SOFC.