Enhanced Ceria Solid Electrolyte Fuel Cell Development. Reduction of ElectronicConductivity Permits Use of a Solid Ceria Electrolyte in High Efficiency High Power Density Fuel Cells at Temperatures Compatible with Metallic Cell Hardware

摘要

The high operating temperature of zirconia based solid oxide fuel cells has beenshown in many studies to have advantages for both space and terrestrial applications. The high heat rejection temperature minimizes radiator size and weight for high atmospheric and space applications. Mobile and stationary terrestrial applications take advantage of a cell temperature high enough to directly reform hydro-carbon fuels, achieving high efficiency and energy density. Government funded solid oxide fuel cell (SOFC) efforts are concentrated on the monolithic and tubular cell designs employing zirconia as the oxide ion conduction membrane. Zirconia requires an operating temperature of 1000 C to achieve adequate electrolyte conductivity. All-ceramic cell structures are used in both cases, leading to fragile, failure prone cells, and manufacturing steps which are difficult to scale up and costly. IFC's molten carbonate fuel cell development demonstrates the reliability of ductile sheet metal parts used for gas flow fields, separator plates, and frames in the 650 C temperature range. Ceria doped with gadolinium has ionic conductivity at 700 C comparable to zirconia at 1000 C. At 700 C a variety of stainless steels offer acceptable strength and oxidation resistance for use as cell hardware. (rrh)