Disclosed are a highly ionic conductive zirconia electrolyte and a high-efficiency solid oxide fuel cell using the same. The highly ionic conductive zirconia electrolyte is configured such that a scandia (Sc.sub.2O.sub.3) stabilized zirconia (ZrO.sub.2) electrolyte is simultaneously doped with cerium oxide (CeO.sub.2) and at least one oxide of gadolinium oxide (Gd.sub.2O.sub.3), samarium oxide (Sm.sub.2O.sub.3), and ytterbium oxide (Yb.sub.2O.sub.3) so that an ionic conductivity drop rate is mitigated.

Disclosed are a highly ionic conductive zirconia electrolyte and a high-efficiency solid oxide fuel cell using the same. The highly ionic conductive zirconia electrolyte is configured such that a scandia (Sc.sub.2O.sub.3) stabilized zirconia (ZrO.sub.2) electrolyte is simultaneously doped with cerium oxide (CeO.sub.2) and at least one oxide of gadolinium oxide (Gd.sub.2O.sub.3), samarium oxide (Sm.sub.2O.sub.3), and ytterbium oxide (Yb.sub.2O.sub.3) so that an ionic conductivity drop rate is mitigated.

In accordance with the present disclosure, a method for fabricating a symmetrical solid oxide fuel cell is described. The method includes synthesizing a composition comprising perovskite and applying the composition on an electrolyte support to form both an anode and a cathode.

A cell according to the present disclosure includes: a solid electrolyte layer including a first surface and a second surface opposite to the first surface; a fuel electrode on the first surface; an air electrode on the second surface; and a middle layer between the second surface and the air electrode. The middle layer=is a CeO.sub.2-type sintered body containing Si, the content of Si equivalent to or less than 150 ppm in terms of SiO.sub.2. A cell stack device includes a cell stack in which the plurality of cells is aligned. A module includes: a storage container; and the cell stack device that is housed in the storage container. A module housing device includes: an external case; the module and an auxiliary equipment that drives the module, which are housed in the external case.

Disclosed herein are barium hafnate comprising proton-conducting electrolytes for use in solid oxide fuel cells. The disclosed electrolytes are also useful for electrolysis operations and for carbon dioxide tolerance.

A cell structure includes a cathode, an anode, and a protonically conductive solid electrolyte layer between the cathode and the anode. The solid electrolyte layer contains a compound having a perovskite structure and containing zirconium, cerium, and a rare-earth element other than cerium. If the solid electrolyte layer has a thickness of T, the elemental ratio of zirconium to cerium at a position 0.25 T from a surface of the solid electrolyte layer opposite the cathode, Zr.sub.C/Ce.sub.C, and the elemental ratio of zirconium to cerium at a position 0.25 T from a surface of the solid electrolyte layer opposite the anode, Zr.sub.A/Ce.sub.A, satisfy Zr.sub.C/Ce.sub.C>Zr.sub.A/Ce.sub.A, and Zr.sub.C/Ce.sub.C>1.

A cell structure includes a cathode, an anode, and a protonically conductive solid electrolyte layer between the cathode and the anode. The solid electrolyte layer contains a compound having a perovskite structure and containing zirconium, cerium, and a rare-earth element other than cerium. If the solid electrolyte layer has a thickness of T, the elemental ratio of zirconium to cerium at a position 0.25 T from a surface of the solid electrolyte layer opposite the cathode, Zr.sub.C/Ce.sub.C, and the elemental ratio of zirconium to cerium at a position 0.25 T from a surface of the solid electrolyte layer opposite the anode, Zr.sub.A/Ce.sub.A, satisfy Zr.sub.C/Ce.sub.C>Zr.sub.A/Ce.sub.A, and Zr.sub.C/Ce.sub.C>1.

A solid oxide fuel cell (SOFC) includes a cathode electrode, a solid oxide electrolyte, and an anode electrode. The electrolyte and/or electrode composition includes zirconia stabilized with (i) scandia, (ii) ceria, and (iii) at least one of yttria and ytterbia. The composition does not experience a degradation of ionic conductivity of greater than 15% after 4000 hrs at a temperature of 850° C.

A solid oxide fuel cell (SOFC) includes a cathode electrode, a solid oxide electrolyte, and an anode electrode. The electrolyte and/or electrode composition includes zirconia stabilized with (i) scandia, (ii) ceria, and (iii) at least one of yttria and ytterbia. The composition does not experience a degradation of ionic conductivity of greater than 15% after 4000 hrs at a temperature of 850° C.

This invention relates to a method for preparing an air electrode based on Pr.sub.2-xNiO.sub.4 with 0≦x<2, comprising a step consisting in sintering a ceramic ink comprising Pr.sub.2-xNiO.sub.4 and a pore-forming agent at a temperature above 1000° C. and below or equal to 1150° C. This invention also relates to the air electrode thus obtained and its uses.