Abstract: A method and apparatus for operating an intermediate-temperature solid-oxide fuel cell stack (10) with a mixed ionic/electronic conducting electrolyte in order to increase its efficiency. The required power output of the sold-oxide fuel cell stack (10) is determined and one or more operating conditions of the solid fuel cell stack (10) are controlled dependent upon the determined required power output. The operating conditions that are controlled may be at least one or the temperature of the fuel cell stack and the dilution of fuel delivered to the fuel cell stack.

Abstract: The fabrication of ceria based electrolytes to densities greater than 97% of the theoretical achievable density at temperatures below 1200° C., preferably approximately 1000° C., is disclosed. The electrolyte has a concentration of divalent cations minus an adjusted concentration of trivalent cations of between 0.01 mole % and 0.1 mole %.

Abstract: A solid oxide fuel cell, comprising: a ferritic stainless steel substrate including a porous region and a non-porous region bounding the porous region; a ferritic stainless steel bi-polar plate located under one surface of the porous region of the substrate and being sealingly attached to the non-porous region of the substrate about the porous region thereof, a first electrode layer located over the other surface of the porous region of the substrate; an electrolyte layer located over the first electrode layer; and a second electrode layer located over the electrolyte layers.