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 μm thick Y‐doped ceria (YDC) layer with a 1 to 1.5 μm thick Y‐doped zirconia (YSZ) layer on the fuel side. The cathode/supports were . The anodes consisted of thin YDC and Ni‐YSZ layers. 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 maximum power density at 600°C, 210 mW/cm 2 , is higher than for previously reported SOFCs.