Low-Temperature Solid-Oxide Fuel Cells Utilizing Thin Bilayer Electrolytes

Solid-oxide fuel cells (SOFCs) with electrolytes that provide high open-circuit voltage (OCV) and low ohmic loss down to 550°C are described. The electrolytes were bilayers consisting of a 4 to 8 i.m thick Y-doped ceria (YDC) layer with a 1 to 1.5 p.m thick Y-doped zir-conia (YSZ) layer on the fuel side. The cathode/supports were La0.85Sr,,1 MnO3-YSZ. The anodes consisted of thin YDC and Ni-YSZ lay-ers. The YDC/YSZ electrolyte SOFCs yielded 85 to 98 % of the theoretical OCV, compared with-50 % for YDC electrolyte SOFCs. The cathode overpotential, which was a main factor limiting SOFC power density, was lower for YDC/YSZ than YSZ electrolytes. The maxi-mum power density at 600°C, 210 mW/cm 2, is higher than for previously reported SOFCs