Development of a Lower Temperature SOFC

Abstract

A major impediment to commercialization of solid oxide fuel cell (SOFC) technology has been high operating temperature. Higher conductivity, and thus lower temperature, oxide electrolytes have existed for some time (ranging from gallates and ceria to bismuth oxide based materials). However, each of these materials has it's own specific issues. Moreover, transitioning from a zirconia electrolyte to one of these alternate electrolytes requires development of an entirely new cell material set. Over the last 20 years we have focused on using the most conductive, and hence lowest temperature, electrolytes. To overcome inherent instability in reducing environments we developed a bilayer bismuth-oxide/ceria electrolyte. To overcome reactivity with more conventional cathode materials we developed a bismuth-ruthenate/bismuth-oxide composite cathode. Finally, these materials were integrated into an anode supported cell resulting in power densities of ~2 W/cm2 at 650{degree sign}C. The materials issues, how they were addressed, and the ultimate performance achieved are discussed.