Abstract: To provide a solid oxide fuel cell system capable of avoiding the reduction of air electrodes. The present invention is a solid oxide fuel cell system including: a fuel cell module, a fuel supply apparatus, a water supply apparatus, an oxidant gas supply apparatus, a reformer, and a control section for controlling the extraction of power, whereby the controller having a shutdown stop circuit for executing a shutdown stop when the fuel cell stack is above the predetermined temperature, and after a shutdown stop, during a period when pressure on the fuel electrode side is sufficiently higher than pressure on the air electrode side, and no reverse flow of oxidant gas to the fuel electrode side is occurring, a temperature drop operation is executed whereby high temperature oxidant gas remaining on the oxidant gas electrode side is discharged.

Abstract: Provided is a solid oxide fuel cell having a service life of approximately 90,000 hours, a level required to encourage the widespread use of SOFC. The solid oxide fuel cell is provided with a solid electrolyte layer, an oxygen electrode layer provided on one side of the solid electrolyte layer, and a fuel electrode layer provided on the other side of the solid electrolyte layer. The oxygen electrode layer is made from a material containing iron or manganese, and the solid electrolyte layer contains an yttria-stabilized zirconia solid electrolyte material having a lanthanoid oxide dissolved therein.

Abstract: Disclosed is a durable solid oxide fuel cell that is less likely to have a problem of a conventional solid oxide fuel cell that an air electrode containing a peroviskite oxide, when exposed to a reducing atmosphere, is separated at the stop of operation, especially shutdown. The solid oxide fuel cell includes an air electrode that is obtained by firing a compact containing a perovskite oxide and sulfur element. The content of the sulfur element in the air electrode as fresh after firing or before the start of power generation is in the range of 50 ppm to 3,000 ppm. The separation of the air electrode is effectively suppressed at the shutdown operation.

Abstract: On the other hand, the possibility of estimating the dopant ratio of a metal element to each ceria crystalline particle using integral-width or half-width obtained by XRD was considered as follows: an XRD peak is shifted depending on the dopant ratio of La to ceria; when La increases, an XRD peak is shifted to a lower angle; in XRD performed on a raw material obtained by mixing ceria crystalline particles having different dopant ratio, peaks corresponding to the respective dopant ratio exist close to each other; as a result, a peak width is widened; accordingly, the dopant ratio of a metal element to each ceria crystalline particles are supposed to vary when integral-width and half-width obtained by XRD are large. Thus, it was revealed for the first time that integral-width and half-width obtained by XRD indicate variations in dopant ratio. It should be noted that from the direct proportional relationship between the dopant ratio x and the integral-width for dopant ratio ranging from 0.35 to 0.

Abstract: Provided is a method for producing a solid oxide fuel cell comprising the following: a fuel gas flow path, a fuel electrode layer provided around the fuel gas flow path and containing an iron group element and a ceramic, a solid electrolyte layer provided around the fuel electrode layer, and an air electrode layer provided around the solid electrolyte layer. In a high-temperature state where the temperature of the solid oxide fuel cell, in which a fuel gas is supplied from one side of the fuel gas flow path and exhausted through an opening provided on the other side of the fuel gas flow path, is close to a power generation temperature, the solid oxide fuel cell is subjected to a process for regulating oxidation expansion rate of the fuel electrode layer, the oxidation expansion occurring when an oxidant gas flows in through the opening.

Abstract: In a fuel cell unit 16 that constitutes a fuel cell module 2 of an SOFC device 1, a collector cap 86a is connected to an inner electrode layer 90 via a seal material 96 as an Ag seal portion. A glass coating 30 (dense body) is filled up between the inner electrode layer 90 and an electrolyte layer 94 and the collector cap 86a to cover an upper end surface 96a of the seal material 96. As such, the fuel cell unit 16 includes the seal material 96 constituting as an Ag seal portion that separates a fuel gas from an oxidant gas, and a glass coating 30 at least partially formed to over at least either the fuel gas side surface of the seal material 96 or an the oxidant gas side surface of the seal material 96.

Abstract: To provide a solid oxide fuel cell system capable of avoiding the reduction of air electrodes. The present invention is a solid oxide fuel cell system including: a fuel cell module, a fuel supply apparatus, a water supply apparatus, an oxidant gas supply apparatus, a reformer, and a control section for controlling the extraction of power, whereby the controller having a shutdown stop circuit for executing a shutdown stop when the fuel cell stack is above the predetermined temperature, and after a shutdown stop, during a period when pressure on the fuel electrode side is sufficiently higher than pressure on the air electrode side, and no reverse flow of oxidant gas to the fuel electrode side is occurring, a temperature drop operation is executed whereby high temperature oxidant gas remaining on the oxidant gas electrode side is discharged.

Abstract: To provide a solid oxide fuel cell capable of executing a shutdown stop while sufficiently suppressing fuel cell oxidation. The present invention is a solid oxide fuel cell system having a fuel cell module, a fuel supply apparatus, a water supply apparatus, a generating air supply apparatus, a reformer, a fuel/exhaust gas passageway for guiding fuel/exhaust gas from a fuel supply apparatus through a reformer to outside; and a controller comprising a shutdown stop circuit; whereby the fuel/exhaust gas passageway functions as a mechanical pressure retention means, maintaining a pressure on the oxidant gas electrode side within the fuel cell module higher than atmospheric pressure, and maintaining a pressure on the fuel electrode side at a pressure higher than the pressure on the oxidant gas electrode side, until the fuel electrode temperature drops to a predetermined oxidation suppression temperature.

Abstract: To provide a solid oxide fuel cell system capable of avoiding the reduction of air electrodes. The present invention is a fuel cell system having: a fuel cell module, a fuel supply apparatus, a water supply apparatus, an air supply apparatus, a reformer, and a control section for controlling the extraction of power from a fuel cell module, whereby the controller includes a shutdown stop circuit for executing a shutdown stop when the fuel cell stack is above the oxidation suppression temperature, and after execution of a shutdown stop, during a period when pressure on the fuel electrode side is sufficiently higher than pressure on the air electrode side, and no reverse flow of air to the fuel electrode side is occurring, a temperature drop operation is executed whereby high temperature air remaining on the air electrode side is discharged.

Abstract: On the other hand, the possibility of estimating the dopant ratio of a metal element to each ceria crystalline particle using integral-width or half-width obtained by XRD was considered as follows: an XRD peak is shifted depending on the dopant ratio of La to ceria; when La increases, an XRD peak is shifted to a lower angle; in XRD performed on a raw material obtained by mixing ceria crystalline particles having different dopant ratio, peaks corresponding to the respective dopant ratio exist close to each other; as a result, a peak width is widened; accordingly, the dopant ratio of a metal element to each ceria crystalline particles are supposed to vary when integral-width and half-width obtained by XRD are large. Thus, it was revealed for the first time that integral-width and half-width obtained by XRD indicate variations in dopant ratio. It should be noted that from the direct proportional relationship between the dopant ratio x and the integral-width for dopant ratio ranging from 0.35 to 0.

Abstract: Problem: To suppress the occurrence of damage to fuel cell units caused by oxidation shrinkage of fuel electrodes. Solution Means: The invention is a solid oxide fuel cell for generating electricity by reacting hydrogen and oxidant gas in individual fuel cell units, wherein the individual fuel cell units comprise a fuel electrode, an oxidant gas electrode, and a solid electrolyte erected between fuel electrode and oxidant gas electrode; the fuel electrode comprises a composite material containing nickel, and the solid oxide fuel cell prevents shrinkage due to oxidation of the fuel electrode by maintaining the fuel electrode in an oxygen-free atmosphere until the temperature of the fuel electrode has dropped to 350° C. after electrical generation is stopped.

Abstract: In a fuel cell unit 16 that constitutes a fuel cell module 2 of an SOFC device 1, a collector cap 86a is connected to an inner electrode layer 90 via a seal material 96 as an Ag seal portion. A glass coating 30 (dense body) is filled up between the inner electrode layer 90 and an electrolyte layer 94 and the collector cap 86a to cover an upper end surface 96a of the seal material 96. As such, the fuel cell unit 16 includes the seal material 96 constituting as an Ag seal portion that separates a fuel gas from an oxidant gas, and a glass coating 30 at least partially formed to over at least either the fuel gas side surface of the seal material 96 or an the oxidant gas side surface of the seal material 96.

Abstract: Disclosed is a durable solid oxide fuel cell that is less likely to have a problem of a conventional solid oxide fuel cell that an air electrode containing a peroviskite oxide, when exposed to a reducing atmosphere, is separated at the stop of operation, especially shutdown. The solid oxide fuel cell includes an air electrode that is obtained by firing a compact containing a perovskite oxide and sulfur element. The content of the sulfur element in the air electrode as fresh after firing or before the start of power generation is in the range of 50 ppm to 3,000 ppm. The separation of the air electrode is effectively suppressed at the shutdown operation.

Abstract: Provided is a solid oxide fuel cell comprising the following: a fuel gas flow path, a fuel electrode layer provided around the fuel gas flow path and containing an iron group element and a ceramic, a solid electrolyte layer provided around the fuel electrode layer, and an air electrode layer provided around the solid electrolyte layer. In a high-temperature state where the temperature of the solid oxide fuel cell, in which a fuel gas is supplied from one side of the fuel gas flow path and exhausted through an opening provided on the other side of the fuel gas flow path, is close to a power generation temperature, the solid oxide fuel cell is subjected to a process for regulating oxidation expansion rate of the fuel electrode layer, the oxidation expansion occurring when an oxidant gas flows in through the opening.

Abstract: Provided is a solid electrolyte material provided which, while maintaining a high oxygen ion conductivity, minimizes the extraction of scandia caused by impurities such as silicon in the fuel gas, and has improved intergranular strength in order to eliminate intergranular fracture caused by crystalline modification. The solid electrolyte material is a zirconia solid electrolyte material having yttria dissolved therein, has cubic crystals as the main ingredient, and is further characterized by having a lanthanoid oxide dissolved therein.

Abstract: Provided is a solid electrolyte material which, while maintaining high oxygen ion conductivity, minimizes the decomposition of scandia caused by impurities such as silicon in the fuel gas, and improves intergranular strength in order to eliminate intergranular fracture caused by crystalline modification. The solid electrolyte material is a zirconia solid electrolyte material having scandia and a lanthanoid oxide and/or yttria dissolved therein, and has alumina further added thereto.

Abstract: Provided is a solid oxide fuel cell having a service life of approximately 90,000 hours, a level required to encourage the widespread use of SOFC. The solid oxide fuel cell is provided with a solid electrolyte layer, an oxygen electrode layer provided on one side of the solid electrolyte layer, and a fuel electrode layer provided on the other side of the solid electrolyte layer. The oxygen electrode layer is made from a material containing iron or manganese, and the solid electrolyte layer contains an yttria-stabilized zirconia solid electrolyte material having a lanthanoid oxide dissolved therein.

Abstract: Provided is a solid oxide fuel cell having a service life of approximately 90,000 hours, a level required to encourage the widespread use of SOFC. The solid oxide fuel cell according to the present invention comprises a solid electrolyte layer, an oxygen electrode layer provide to one side of the solid electrolyte layer, and a fuel electrode layer provide to the other side of the solid electrolyte layer. The oxygen electrode layer is made from a material including iron or manganese, the solid electrolyte layer is made from a scandia-stabilized zirconia electrolyte material containing alumina, and the solid electrolyte layer has a lanthanoid oxide and/or yttria dissolved therein.