Solid electrolyte includes a first solid electrolyte that is a phosphate salt including Li and Ta, and a second solid electrolyte that is NASICON type solid electrolyte. In a cross section of the solid electrolyte, an area ratio of the first solid electrolyte is more than 10% and an area ratio of the second solid electrolyte is more than 10%.

A lithium ion conductive solid electrolyte or an all-solid-state battery. The lithium ion conductive solid electrolyte satisfies any of (I) to (III): (I) having a crystal structure based on LiTa.sub.2PO.sub.8 and a crystal structure based on at least one compound selected from LiTa.sub.3O.sub.8, Ta.sub.2O.sub.5, and TaPO.sub.5; (II) being represented by the stoichiometric formula of Li.sub.a1Ta.sub.b1B.sub.c1P.sub.d1O.sub.e1 where 0.5<a1<2.0, 1.0<b1≤2.0, 0<c1<0.5, 0.5<d1<1.0, and 5.0<e1≤8.0; (III) being represented by the stoichiometric formula of Li.sub.a2Ta.sub.b2Ma.sub.c2B.sub.d2P.sub.e2O.sub.f2 where 0.5<a2<2.0, 1.0<b2≤2.0, 0<c2<0.5, 0<d2<0.5, 0.5<e2<1.0, and 5.0<f2≤8.0, and Ma is one or more elements selected from the group consisting of Nb, Zr, Ga, Sn, Hf, Bi, W, Mo, Si, Al, and Ge.

A high-temperature fuel cell system includes a reformer that reforms a hydrocarbon-based raw fuel to generate a reformed gas containing hydrogen, a fuel cell that generates power by using the reformed gas and an oxidant gas, and a burner that heats the reformer. The burner includes an anode-off-gas gathering portion that has an anode-off-gas ejection hole and at which an anode off-gas discharged from an anode of the fuel cell gathers. The anode-off-gas gathering portion surrounds a first cathode-off-gas passing area through which a cathode off-gas discharged from a cathode of the fuel cell passes. The anode-off-gas ejection hole is formed such that the anode off-gas ejected upward from the anode-off-gas ejection hole approaches the cathode off-gas passing upward through the first cathode-off-gas passing area. The anode off-gas ejected from the anode-off-gas ejection hole and the cathode off-gas that has passed through the first cathode-off-gas passing area are burned.

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 system and a method for forming a composite electrolyte structure are provided. An exemplary composite electrolyte structure includes, at least in part, polymer electrolyte preforms that are bonded into the composite electrolyte structure.

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.

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 method for producing a porous element is presented. A powdery metal-ceramic composite material is produced. The composite material has a metal matrix and a ceramic portion amounting to less than 25 percent by volume. The metal matrix is at least partially oxidized to obtain a metal oxide. The metal-ceramic composite material is grinded and mixed with powdery ceramic supporting particles to obtain a metal-ceramic/ceramic mixture. The metal-ceramic/ceramic mixture is shaped into the porous element. The porous element can be used as an energy storage medium in a battery.

A SOFC system for producing a refined carbon dioxide product, electrical power, and a compressed hydrogen product is presented. The system can include a hydrodesulfurization system, a steam reformer, a water-gas shift reactor system, a hydrogen purification system, a hydrogen compression and storage system, a pre-reformer, and a CO2 purification and liquidification system.

An apparatus of power generation is provided. The apparatus uses a stack of dense solid oxide fuel cells (SOFC). The exhaust gas generated by a burner of the apparatus enters into the SOFC stack for heating. At the same time, the SOFC stack is heated by the thermal radiation and heat transfer of the burner as well as the thermal convection of gases between the anode and the cathode. Thus, the SOFC stack is heated to reach an operating temperature for generating power without any additional electroheat device. The present invention has a simple structure, flexible operation. Moreover, it increased efficiency, reduced pollutant emission with lowered costs of equipment and operation.