Fester Elektrolyt für eine Brennstoffzelle und sein Herstellungsverfahren

摘要

The present invention relates to a solid electrolyte consisting essentially of cerium oxide for a fuel cell, this solid electrolyte being prevented from becoming reduced under the effect of a fuel gas of a fuel cell. The present invention also relates to a method for producing this solid electrolyte and to a high-temperature-type fuel cell utilizing this solid electrolyte, This solid electrolyte for a fuel cell comprises: (a) a specifically-shaped solid electrolyte consisting essentially of cerium oxide, the solid electrolyte having a fluorite-type structure and oxide-ionic conduction, and (b) a perovskite-type oxide having an ABO3-type composition, which is a solid electrolyte of proton/oxide-ionic mixed conduction and is bonded as a membrane on a portion of one surface of the solid electrolyte consisting essentially of cerium oxide, in which (i) A of the "ABO3" represents at least one element selected from the group consisting of alkaline earth metals, (ii) B of the "ABO3" represents cerium by itself or cerium and at least one element selected from the group consisting of alkaline earth metals and rare earth elements, the elements selected from alkaline earth metals and rare earth elements substituting the cerium by 1 to 30 mol%. The method for producing the solid electrolyte for a fuel cell comprises the steps of: preparing a specifically-shaped solid electrolyte consisting essentially of cerium oxide which has a fluorite-type structure and oxide-ionic conduction, coating a solid electrolyte membrane of proton/oxide-ionic mixed conduction on the part of the surface of the solid electrolyte consisting essentially of cerium oxide, and firing the specifically-shaped solid electrolyte coated at a temperature higher than a given temperature. A fuel cell comprising the above mentioned solid electrolyte shows excellent high-temperature characteristics.