Improvement of Open Circuit Voltage (OCV) depending on Thickness of GDC Electrolyte of LT-SOFCs

It has been considered to apply GDC (Gd0.1Ce0.9O1-X) for low-temperature SOFC electrolytes because it has higher ionic conductivity than YSZ at low temperature. However, open circuit voltage with using GDC (Gd0.1Ce0.9O1-X) electrolyte in SOFCs, becomes lower than using YSZ (8 mol% Yttria stabilized Zirconia) electrolyte because GDC has electronic conductivity. In this work, the effect of changing GDC electrolyte thickness on the open circuit voltage has been investigated. Ni-GDC anode-supported unit cells were fabricated as follows. Mixed NiO-GDC powders were pressed and pre-sintered at 1200 degrees C. And then, GDC electrolyte material was dip-coated on the anode and sintered at 1400 degrees C. Finally the LSCF-GDC cathode material was screen-printed on the electrolyte and sintered at 1000 degrees C. Electrolyte thickness was controlled by the number of dip-coating times. Open circuit voltage was measured depending on electrolyte thickness at 650 degrees C and found that the thicker GDC electrolyte was, the better OCV was.