Influence of characteristics of stabilized zirconia electrolyte on performance of cermet supported tubular SOFCs

M-Al₂O₃ cermet supported tubular SOFC was fabricated by thermal spraying. Flame-sprayed Al₂O₃-Ni cermet coating plays dual roles of a support tube and an anode current collector. 4.5 mol.% yttria-stabilized zirconia (YSZ) and 10 mol.% scandia-stabilized zirconia (ScSZ) coatings were deposited by atmospheric plasma spraying (APS) as the electrolyte in present study. The electrical conductivity of electrolyte was measured using DC method. The post treatment was employed using nitrate solution infiltration to densify APS electrolyte layer for improvement of gas permeability. The electrical conductivity of electrolyte and the performance of single cell were investigated to optimize SOFC performance. The electrical conductivity of the as-sprayed YSZ and ScSZ coating is about 0.03 and 0.07 S·cm^-1 at 1000°C, respectively. The ohmic polarization significantly influences the performance of SOFC. The maximum output power density at 1000°C increases from 0.47 to 0.76 W·cm^-2 as the YSZ electrolyte thickness reduces from 100 μm to 40 μm. Using APS ScSZ coating of about 40 μm as the electrolyte, the test cell presents a maximum power output density of over 0.89 W·cm^-2 at 1000°C.