A COMPOSITE ELECTROLYTE FOR AN SOFC CONSISTING OF A CERIA SHEET AND A ZIRCONIA FILM DEPOSITED BY THE SOL-GEL METHOD

<jats:title>ABSTRACT</jats:title><jats:p>We investigated a composite electrolyte for solid oxide fuel cells prepared by coating a ceria sheet (Ce<jats:sub>0.8</jats:sub>Gd<jats:sub>0.2</jats:sub>O<jats:sub>2-d</jats:sub> or GDC ) with a scandia alumina doped zirconia (0.850ZrO<jats:sub>2</jats:sub>-0.110Sc<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>-0.04Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>) film by the sol-gel method. The sol-gel film annealed at 1200°C was examined by X-ray diffraction analysis and found to be in a cubic phase at room temperature. The ionic conductivity of this film is comparable to that of bulk sintered at 1620°C. Scanning electron microscope observations revealed that the film forms a good interface with the electrolyte of the ceria sheet, even though the annealing temperature is as low as 1200°C.</jats:p><jats:p>We fabricated a single cell consisting of a composite electrolyte, a La<jats:sub>0.8</jats:sub>Sr<jats:sub>0.2</jats:sub>MnO<jats:sub>3</jats:sub> cathode and a Ni-YSZ anode. The composite electrolyte consisted of zirconia film about one micron thick deposited by the sol-gel method and a 0.2 mm thick ceria sheet.</jats:p><jats:p>A cell operated with moist H<jats:sub>2</jats:sub> and O<jats:sub>2</jats:sub> gas exhibited an open circuit voltage of 1.00 V at 800°C. This value is much closer to the value of 1.13 V expected from the Nernst equation than the value of 0.76 V for a cell with a ceria sheet but without the sol-gel film.</jats:p>