JP2008034373A - Solid oxide type fuel cell, cooling method thereof, and solid oxide type fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid oxide type fuel cell that can be miniaturized and thinned, and prevents a module from being damaged by thermal stress generated when temperature rises due to operation or when temperature decreases due to stop, to provide a cooling method of the solid oxide type fuel cell, and to provide a solid oxide type fuel cell system. <P>SOLUTION: In the fuel cell 1, a gas supply pipe 7 having an air supply and exhaust hole 7a for supplying and exhausting fuel or air is provided at a through hole 55 formed at the outer-periphery of an interconnector 3 with a gap 58 for stacking. Then, the fuel cell 1 is composed so that the outer-periphery surface of the gas supply pipe 7 adheres to the inner-periphery surface of the through hole 55 at operating temperature. At the operating temperature, the outer-periphery surface of the gas supply pipe 7 and the inner-periphery surface of the through hole 55 are caulked and adhered due to the thermal expansion of the gas supply pipe 7 and the interconnector 3, thus preventing the gas supply pipe 7 and the interconnector 3 from being damaged by thermal expansion. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid oxide fuel cell (SOFC) using a solid electrolyte, a cooling method thereof, and a solid oxide fuel cell system.

  In recent years, power consumption has increased with the increase in the number of functions of portable devices, and as a result, the duration of batteries has rapidly decreased. There are a primary battery and a secondary battery as types of batteries, but the duration does not satisfy the user's request. Therefore, although not yet commercialized, expectations for micro fuel cells are increasing in terms of high energy density and long duration.

  As a form of the micro fuel cell, in general, a polymer electrolyte fuel cell (PEFC) has been developed mainly from the viewpoint of heat dissipation and operating temperature, and the shape is such that a channel groove is provided in the substrate. A stacked type is known. However, the polymer electrolyte fuel cell is not desirable from the viewpoint of low power generation efficiency and the use of a large amount of a noble metal catalyst.

  On the other hand, a solid oxide fuel cell (SOFC) is a relatively large fuel cell that has been developed. Since a conventional solid oxide fuel cell wants to obtain a large output, it has been stacked using a plurality of cells having the same form in which a fuel electrode and an air electrode are arranged via an electrolyte (for example, a patent) Reference 1).

  Solid oxide fuel cells have high power generation efficiency and are expected to be applied to portable devices, but high operating temperatures have been a bottleneck. However, due to recent research and development, the operating temperature has been lowered from the conventional 1000 ° C. to 600 to 800 ° C., and the possibility of use as a highly efficient micro fuel cell has been realized.

JP 2003-132933 A

  However, the solid oxide fuel cell has a relatively large cell, and for application to a portable device, it is necessary to make the size of the fuel cell main body as small as possible while ensuring a minimum output. In other words, solid oxide fuel cells require element designs that enable "small" and "rapid start-up" for their intended purpose, and are relatively large stationary solid oxides that have been developed in the past. The fuel cell has created new challenges that have not been studied.

  In a solid oxide fuel cell, in order to obtain a practically sufficient amount of power generation, a plurality of cells are electrically connected using an interconnector, but the cells are stacked to form a stack. In some cases, since the operating temperature is high, it becomes a problem that the joint is damaged due to the thermal stress between the constituent members. Moreover, a crack may arise in a cell or an interconnector, and electric power generation may become impossible. In conventional stationary solid oxide fuel cells, it is possible to maintain strength in size, but damage to members due to thermal stress caused by temperature rise due to operation or temperature drop due to shutdown while reducing size It was difficult to prevent.

  An object of the present invention is to provide a solid oxide fuel cell that can be reduced in size and thickness, and that prevents damage to a module due to thermal stress caused by temperature rise due to operation or temperature drop due to stop, and solid oxide A cooling method for preventing damage to a fuel cell and a solid oxide fuel cell system.

  In order to solve the above problems, according to the present invention, an electrolyte layer, a fuel electrode layer formed on the electrolyte layer, and an air electrode layer formed on a surface opposite to the fuel electrode layer on the electrolyte layer, A stack in which cells and interconnectors are alternately stacked, and an interconnector that arranges cells on a first surface side that is one surface and a second surface side that is the other surface. Further, the flow path forming members that form the flow paths of the air and the fuel in the stack have different mutual adhesion depending on the temperature, and each flow path forming member is caused by a difference in thermal expansion of each flow path forming member at the operating temperature. The thermal expansion seal portion is formed by improving the adhesion between them, and the thermal expansion seal portion provides a solid oxide fuel cell that prevents the air and fuel flowing in the stack from leaking to the outside.

  Specifically, the interconnector has a passage portion for supplying and exhausting fuel and air to and from each electrode of the cell, and an outer peripheral portion having a through-hole communicating with the passage portion and penetrating in the height direction. And interconnectors are alternately stacked, and a gas supply pipe having air supply / exhaust holes for supplying and exhausting fuel or air in the passage portion is provided with a gap in the through hole to form a stack structure. There is provided a solid oxide fuel cell in which there is no gap at the operating temperature, and the outer peripheral surface of the gas supply pipe and the inner peripheral surface of the through hole are in close contact to form a thermal expansion seal portion.

  More specifically, in the solid oxide fuel cell of the present invention, the outer peripheral surface of the gas supply pipe and the inner peripheral surface of the through hole are caulked by a difference in thermal expansion between the gas supply pipe and the interconnector at the operating temperature. Configure to be in close contact.

  In order to solve the above problems, according to the present invention, cells and interconnectors are alternately stacked in a state where the outer periphery of the cell is sandwiched between the first surface and the second surface of the outer periphery of the interconnector. A stack structure is formed, an air circulation part through which air flows is formed on the first surface side of the interconnector, a fuel circulation part through which fuel flows is formed on the second surface side, and the outer peripheral part of the cell The adhesion between the front and back surfaces of the interconnector and the first and second surfaces of the outer peripheral portion of the interconnector varies depending on the temperature, and the adhesion is improved by the difference in thermal expansion at the operating temperature to form a thermal expansion seal portion An oxide fuel cell is also provided.

  In this solid oxide fuel cell, on the side surface of the stack in which the cells and the interconnector are stacked, a sealing member for preventing the air flowing through the air circulation portion and the fuel flowing through the fuel circulation portion from leaking to the outside is disposed. You can also

  And a sealing member can be formed with the composite material which impregnated glass to the porous aggregate. Furthermore, it can be set as the structure which joins a ceramic to the outer side of a sealing member.

  In order to solve the above problems, according to the present invention, an electrolyte layer, a fuel electrode layer formed on the electrolyte layer, and an air electrode formed on a surface opposite to the fuel electrode layer on the electrolyte layer. A stack having cells and interconnectors alternately stacked, the cell having a layer, and an interconnector that arranges the cells on the first surface side that is one surface and the second surface side that is the other surface A solid oxide fuel cell cooling method in which hydrogen is generated from an operating temperature to a predetermined set temperature lower than the operating temperature and higher than the normal temperature when the operation of the solid oxide fuel cell is stopped. A method for cooling a solid oxide fuel cell in which gas is supplied to a stack for cooling is provided. Furthermore, after that, it is preferable to cool the stack by supplying air from the set temperature. The set temperature is preferably 300 ° C to 500 ° C, and particularly preferably 350 ° C to 450 ° C.

  Furthermore, in order to solve the above problems, according to the present invention, an electrolyte layer, a fuel electrode layer formed on the electrolyte layer, and an air formed on a surface opposite to the fuel electrode layer on the electrolyte layer are provided. A cell having a polar layer, and an interconnector for arranging the cell on the first surface side which is one surface and the second surface side which is the other surface, and the cells and the interconnector are alternately stacked. A solid oxide fuel cell in which a stack is formed, an air supply unit that supplies air to the solid oxide fuel cell, a fuel supply unit that supplies fuel to the solid oxide fuel cell, and a solid oxide type A temperature sensor for measuring the temperature of the fuel cell, and the temperature of the solid fuel cell measured by the temperature sensor is controlled from the operating temperature to a predetermined set temperature to control the fuel supply unit to supply hydrogen gas to the stack for cooling A solid acid containing a control unit Things fuel cell system is provided. Furthermore, the control unit can be configured to control the air supply unit to supply air to the stack and cool it below the set temperature.

  In the solid oxide fuel cell of the present invention, a stack in which cells and interconnectors are alternately stacked is formed, and the mutual adhesion of members forming air and fuel flow paths in the stack varies depending on the temperature. Since the adhesiveness between the members is improved by the difference in thermal expansion of each member at the operating temperature, the low stress stack structure can be obtained without accumulating the thermal stress generated by the rapid temperature rise. Since the adhesion between the members is improved at the operating temperature, the thermal expansion seal portion is formed, and it is possible to prevent the air and fuel flowing through the stack from leaking to the outside.

  Specifically, the solid oxide fuel cell of the present invention is formed by alternately stacking cells and interconnectors because the interconnectors have accommodating portions. In addition, since the interconnector has a passage portion for supplying and exhausting fuel and air to and from each electrode of the cell, and an outer peripheral portion, there is a through-hole communicating with the passage portion and penetrating in the height direction. A gas supply pipe having an air supply / exhaust hole can be provided to supply air and fuel to the cell. Further, the gas supply pipe is provided with a gap in the through-hole, and the outer peripheral surface of the gas supply pipe and the inner peripheral surface of the through-hole are in close contact with each other at the operating temperature so that there is no gap. Sometimes, damage to the solid oxide fuel cell due to thermal stress can be prevented. By sealing the joint between the gas supply pipe and the stack (interconnector) firmly at the operating temperature without being firmly fixed, a highly durable structure can be obtained against rapid temperature rise and fall.

  Furthermore, in the solid oxide fuel cell of the present invention, the cells and the interconnector are alternately stacked in a state where the outer periphery of the cell is sandwiched between the first surface and the second surface of the outer periphery of the interconnector. A stack structure can be used, and the adhesiveness between the front and back surfaces of the outer peripheral portion of the cell and the first and second surfaces of the outer peripheral portion of the interconnector is different depending on the temperature. Adhesion is improved by the difference in expansion, and leakage of air and fuel can be prevented.

  The solid oxide fuel cell cooling method of the present invention stacks hydrogen gas from an operating temperature to a preset temperature lower than the operating temperature and higher than the normal temperature when the operation of the solid oxide fuel cell is stopped. By supplying to and cooling the cell, it is possible to prevent the cell from being destroyed due to volume shrinkage accompanying the oxidation of nickel contained in the cell.

  The solid oxide fuel cell system of the present invention includes a temperature sensor, and the control unit controls the fuel supply unit from the operating temperature to a predetermined set temperature to supply hydrogen gas to the stack for cooling. Below the set temperature, the air supply unit can be controlled to supply air to the stack for cooling. Thereby, the destruction of the cell due to the volume fluctuation accompanying the oxidation of nickel contained in the cell can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the invention.

  FIG. 1 is a partial perspective view of a solid oxide fuel cell (hereinafter also simply referred to as a fuel cell) 1 of the present invention. FIG. 2 shows a cross-sectional view taken along a cross-section A in FIG. In the fuel cell 1, cells 2 and interconnectors 3 are alternately stacked to form a stack.

  As shown in FIG. 2, the cell 2 includes an electrolyte layer 11, a fuel electrode layer 12 formed on the electrolyte layer 11, and an air electrode formed on a surface opposite to the fuel electrode layer 12 on the electrolyte layer 11. The layer 13 is formed in a flat plate shape. The fuel electrode layer 12 and the air electrode layer 13 of the cell 2 are formed as porous electrode layers. For example, the fuel electrode layer 12 is Ni-YSZ (yttria stabilized zirconia), and the air electrode layer 13 is LSM (lanthanum strontium). Manganite) and electrolyte layer 11 can be formed of YSZ (yttria stabilized zirconia).

  In the cell 2, the fuel electrode layer 12 is formed by the printing method on the electrolyte fired body (firing condition: 1400 ° C./1 hour) constituting the electrolyte layer 11 prepared by the green sheet method, and fired at 1400 ° C./1 hour. The air electrode layer 13 is formed by the same printing method and then fired at 1200 ° C. for 1 hour. In the present invention, the dense zirconia electrolyte layer 11 is 30 μm, the fuel electrode layer 12 is formed on both surfaces of the electrolyte layer 11, the air electrode layer 13 is formed 20 μm, and the substrate thickness (cell thickness) is 70 μm. The cell 2 was formed with a size of 30 mm × 30 mm. The present invention is greatly reduced in size as compared with a conventional oxide fuel cell by adopting a junction structure with an interconnector 3 as will be described later, and can be used for a battery of a portable electric device. .

  FIG. 3 shows a partially enlarged view of FIG. As shown in FIG. 3, cells 2 and interconnectors 3 are alternately stacked to form a stack structure. Further, as a material for the interconnector 3, Ni-based heat-resistant alloys such as ferrite SUS, Inconel 600, and Hastelloy can be used.

  As shown in FIGS. 2 and 3, the fuel cell 1 as shown in FIG. 1 can be formed by alternately stacking the cells 2 and the interconnectors 3 to form a stack. In this case, each cell 2 has the fuel electrode layer 12 arranged in the same direction (that is, the air electrode layer 13 in the same direction).

  The joining of the interconnector 3 and the cell 2 will be described with reference to FIGS. 4 (a) and 4 (b). The interconnector 3 and the cell 2 may be brazed after forming a Ni-Mn metallized layer on the air electrode layer 13 or the fuel electrode layer 12, or using an active brazing material containing an active metal such as Ti. Although it may be directly joined, as shown in FIG. 4A, the brazing material 61 is attached to the outer peripheral portion of the cell 2 so that the porous electrode layer (air electrode layer 13 or fuel electrode layer 12) is brazed. Densify. Specifically, in a state where the conductive material is sandwiched between the cell 2 and the interconnector 3, the conductive material is dissolved while decompressing the space region on the interconnector 3 side partitioned by the cell 2. As shown in FIG. 4B, the cell 2 and the interconnector 3 can be joined by allowing the brazing material 61 to penetrate into the porous electrode layer and densifying the porous electrode layer. Alternatively, the brazing material 61 may be infiltrated into the porous electrode layer simply by pressurizing at the time of joining, thereby densifying the porous electrode layer. Thereby, the outer peripheral part of the porous electrode layer can be used as the seal part 29. The interconnector 3 and the cell 2 may be joined after densifying the porous electrode layer with the brazing material 61, or densification and joining may be performed simultaneously. Alternatively, the porous electrode layer may be densified using a glass material to form the seal portion 29.

  In the fuel cell 1 in which the fuel electrode layer 12 contains nickel, transformation into nickel oxide occurs in an oxygen atmosphere, and the cell 2 is likely to be destroyed. Therefore, after the nickel in the fuel electrode layer 12 is reduced, the cell 2 and the interconnector 3 may be connected by a brazing material 61 that is a conductive substance.

The brazing material thickness is preferably 10-30 μm from the viewpoint of obtaining good electrical conductivity and sealing properties. The brazing atmosphere is performed at a vacuum of 1 × 10 ⁻³ Pa or less, and the pressure difference between the inside and outside of the interconnector 3 is set to 5 × 10 ⁻⁴ Pa or more, so that the brazing material 61 is impregnated into the porous electrode layer. be able to.

  As the brazing material, it is desirable to select a brazing material excellent in oxidation resistance since the operating environment of the element is an oxidizing atmosphere of 600 to 800 ° C. Specifically, there are Ag-based, Cu-based, and Ni-based materials, but Ni-based materials are desirable from the viewpoint of oxidation resistance. Specifically, Icronibsi 13 (product name) and Cronisi (product name) of USA WESGO, Inc., and US company Walcol Monoy's Microbraz 31 (product name) can be used.

  The interconnector 3 includes a passage portion 56 that supplies and exhausts fuel and air to and from each electrode of the cell 2 (that is, to the accommodating portion 20), and a through hole that communicates with the passage portion 56 in the outer peripheral portion and penetrates in the height direction. 55.

  As shown in FIG. 5, a gas supply pipe 7 having a supply / exhaust hole 7 a for supplying / exhausting fuel or air to / from the passage portion 56 is formed in a gap 58 in a through hole 55 formed in the outer peripheral portion of the interconnector 3. Are provided and stacked. As shown in FIGS. 2 and 3, the fuel cell 1 includes a fuel flow path portion between the interconnector 3 and the fuel electrode layer 12 of the cell 2, and between the interconnector 3 and the air electrode layer 13 of the cell 2. An air flow path portion is formed, and power generation can be performed. The interconnectors 3 are stacked with a gap 59 to prevent a short circuit. In addition, as shown in the cross-sectional view of FIG. 2, the fuel flow path portions 32 and the air flow path portions 31 are alternately formed in the stack direction. Thus, a high voltage can be obtained by stacking.

  Further, as shown in FIG. 3, the stacked fuel cell 1 is provided with the gas supply pipe 7 with a gap 58 in the through hole 55 at normal temperature (before operation), and at the operation temperature, As shown in FIG. 6, the outer peripheral surface of the gas supply pipe 7 and the inner peripheral surface of the through hole 55 are in close contact with each other. That is, at the operating temperature, the outer peripheral surface of the gas supply pipe 7 and the inner peripheral surface of the through hole 55 are caulked by the difference in thermal expansion between the gas supply pipe 7 and the interconnector 3 and are in close contact with each other. For this reason, the damage by the thermal expansion difference of the gas supply pipe 7 and the interconnector 3 can be prevented.

  In other words, the mutual adhesion of the flow path forming members (in this embodiment, the gas supply pipe 7 and the interconnector 3) that form air and fuel flow paths in the stack differs depending on the temperature. Due to the difference in thermal expansion of the path forming member, the adhesion between the flow path forming members is improved, and the thermal expansion seal portion 30 is formed to prevent the air and fuel flowing through the stack from leaking to the outside.

  As shown in FIG. 7, the fuel cell 1 of the present invention includes an air supply unit 67 that supplies air, a fuel supply unit 68 that supplies fuel such as hydrogen gas, a temperature sensor 65 that measures the temperature of the fuel cell 1, and The measurement result of the temperature sensor 65 is inputted, and the solid oxide fuel cell system 100 including the control unit 66 that controls the air supply unit 67 and the fuel supply unit (reformer) 68 is configured. The temperature sensor 65 is not particularly limited as long as it has durability at an operating temperature (for example, 600 to 800 ° C.), and is not particularly limited. For example, a micro thermocouple may be inserted. The temperature dependence of the electrical resistance of the metal thin film can also be used. The controller 66 stores a preset temperature (which may be in the range of 300 ° C. or higher and 500 ° C. or lower, but 400 ° C., for example).

  In the solid oxide fuel cell system 100 including the fuel cell 1 as described above, when a gas containing oxygen is introduced at a high temperature for cooling the module when the system is stopped, the nickel contained in the cell 2 is changed to nickel oxide. Transformation may occur abruptly, leading to cell 2 destruction. Therefore, the solid oxide fuel cell system 100 of the present invention cools the module by performing cooling to a set temperature with hydrogen gas and then flowing air as follows.

  The operation stop process in the solid oxide fuel cell system 100 will be described with reference to FIG. The controller 66 monitors whether the system operation is stopped (S1). When the operation of the system is stopped (S1: YES), hydrogen gas is continuously supplied by the fuel supply unit 68 (S2).

  Based on the signal from the temperature sensor 65, the controller 66 monitors whether the temperature of the module is 400 ° C. or less (S3). If the temperature of the module is 400 ° C. or lower (S3: YES), the control unit 66 stops supplying hydrogen gas and starts supplying air (S4).

  Further, the control unit 66 monitors whether the temperature of the module reaches room temperature based on a signal from the temperature sensor 65 (S5), and if the temperature of the module is sufficiently cooled (near room temperature, for example, 100 ° C.) (S5). : YES), the supply of air is stopped (S6).

  As described above, by cooling with hydrogen gas to a set temperature (for example, 400 ° C.) and cooling with air below that temperature, the destruction of the cell 2 due to volume fluctuations accompanying oxidation of nickel contained in the cell 2 Can be prevented.

  Moreover, in the said structure, the accommodating part which has a level | step-difference part in the interconnector 1 may be provided, and you may comprise so that the cell 2 may be accommodated in the accommodating part. That is, the first housing portion and the second housing portion are formed in a recessed shape by the bottom surface portion 23 and the peripheral wall portion, the step portion is formed in the peripheral wall portion, and the cell 2 is disposed in the step portion, thereby providing a step difference. The outer peripheral part of the cell 2 in contact with the part is a seal part 29, the gap between the air electrode layer 13 and the bottom part 23 is the air circulation part 31, and the gap between the fuel electrode layer 12 and the bottom part 23 is the fuel circulation part 32. It can also be set as the structure made. Furthermore, at least a part of the seal portion 29 may be an electrical conduction portion, and the cell 2 and the interconnector 3 may be electrically connected. Specifically, the fuel electrode layer 12 and the air electrode layer 13 formed as a porous electrode layer are formed by being densified with a conductive material. A brazing material can be used as the conductive material.

  The fuel cell 1, the cooling method, and the solid oxide fuel cell system that form a gap between the gas supply pipe and the interconnector described above can be applied to a circular embodiment as shown in FIG. .

  The cell 2 includes an electrolyte layer 11, a fuel electrode layer 12 formed on the electrolyte layer 11, and air formed on a surface opposite to the fuel electrode layer 12 on the electrolyte layer 11, as in the above-described embodiment. The electrode layer 13 is formed. A cell through hole 15 is formed in order to circulate fuel and air.

  The interconnector 3 has a first housing portion 20a and a second housing that are formed in a recessed shape for arranging the cells 2 on the first surface side that is one surface and the second surface side that is the other surface. Part 20b is formed, the fuel electrode layer 12 is placed inside the first housing part 20a and the cell 2 is housed, and the air electrode layer 13 is housed inside the second housing part 20b and the cell 2 is housed. And the interconnector 3 are alternately stacked to form a stack structure. The details are the same as in the above-described embodiment, and thus the description thereof is omitted.

  The above-described cooling method for cooling to the set temperature with hydrogen gas is not limited to the above-described fuel cell 1. Next, another embodiment of the fuel cell 1 to which the above-described cooling method can be applied will be described with reference to FIGS.

  FIG. 10 is a partially broken perspective view of a fuel cell 1 according to another embodiment, and FIG. 11 is a perspective view showing assembly. The fuel cell 1 has a stack structure in which cells 2 and interconnectors 3 are alternately stacked. FIG. 12 is a cross-sectional view showing the interconnector 3.

  As shown in FIGS. 11 and 12, the interconnector 3 is formed in a recessed shape for arranging the cells 2 on the first surface side which is one surface and the second surface side which is the other surface. The first accommodating portion 20a and the second accommodating portion 20b, which are the accommodating portions 20, are formed, the cell 2 is accommodated in the first accommodating portion 20a with the air electrode layer 13 inside, and the fuel electrode is defined in the second accommodating portion 20b. The cell 12 is accommodated with the layer 12 on the inside, and the cell 2 and the interconnector 3 are alternately stacked to form a stack structure.

  The first housing portion 20 a and the second housing portion 20 b of the interconnector 3 are formed in a shape that is depressed by the bottom surface portion 23 and the peripheral wall portion 24, and the step portion 25 is formed in the peripheral wall portion 24. The interconnector 3 is further provided with an extended step portion 26 that extends from the step portion 25 in the center direction, and a connector through hole 28 is formed in the extended step portion 26. The extending step portion 26 of the interconnector 3 is formed as a pair at diagonal positions where the first housing portion 20a side and the second housing portion side 20b do not face each other.

  As shown in FIG. 11, the fuel cells 1 as shown in FIG. 10 can be formed by alternately stacking the cells 2 and the interconnectors 3 to form a stack. In this case, each cell 2 is arranged so that the fuel electrode layer 12 is in the same direction (that is, the air electrode layer 13 is also in the same direction), and the cell through holes 15 are arranged alternately. Moreover, the interconnector 3 is arrange | positioned so that the position of the extension level | step-difference part 26 may become alternate. By doing in this way, since air and fuel can distribute | circulate widely in the 1st accommodating part 20a and the 2nd accommodating part 20b, electric power generation efficiency can be made high.

  FIG. 13 shows a cross-sectional view of the laminated structure. As shown in FIG. 13, the cell 2 is accommodated in the first accommodating portion 20a and the second accommodating portion 20b of the interconnector 3, and the cells 2 and the interconnector 3 are alternately stacked to form a stack. By disposing the cell 2 in the stepped portion 25, the outer peripheral portion of the cell 2 in contact with the stepped portion 25 is used as the seal portion 29, and the gap between the air electrode layer 13 and the bottom surface portion 23 is defined as the air circulation portion 31 and the fuel electrode layer. A gap between the bottom surface portion 12 and the bottom surface portion 23 serves as a fuel circulation portion 32.

  Further, at least a part of the seal portion 29 is an electric conduction portion, and the cell 2 and the interconnector 3 are electrically connected. The fuel electrode layer 12 and the air electrode layer 13 of the cell 2 are formed as porous electrode layers, and the electrically conductive portion is formed by densifying the porous electrode layer with a conductive substance. Specifically, a brazing material 61 can be used as the conductive material.

  As shown in FIG. 14, the fuel cell 1 formed by stacking as described above has a fuel flow path between the interconnector 3 and the fuel electrode layer 12 of the cell 2, and the interconnector 3 and the cell 2. An air channel portion is formed between the air electrode layer 13 and power generation can be performed. The interconnectors 3 are stacked with a gap in order to prevent a short circuit. Further, as shown in the sectional view of FIG. 13, the fuel flow path portions 32 and the air flow path portions 31 are alternately formed in the stack direction. Thus, by stacking, high output and high voltage can be obtained. In addition, a current collecting member, for example, a metal mesh may be provided in the fuel flow path portion 32 and the air flow path portion 31.

  Furthermore, another embodiment of the solid oxide fuel cell of the present invention will be described with reference to FIGS. FIG. 16 is a partially broken perspective view of the fuel cell 1 of the present embodiment, and FIG. 17 is a cross-sectional view. The solid oxide fuel cell 1 of the present embodiment is formed on the surface opposite to the electrolyte layer 11, the fuel electrode layer 12 formed on the electrolyte layer 11, and the fuel electrode layer 12 on the electrolyte layer 11. A cell 2 having an air electrode layer 13 and an interconnector 3 in which the cell 2 is disposed on the first surface 3a side which is one surface and the second surface 3b side which is the other surface. And the interconnector 3 are alternately stacked.

  Specifically, the cell 2 and the interconnector 3 are alternately stacked while the outer periphery of the cell 2 is sandwiched between the first surface 3a and the second surface 3b of the outer periphery of the interconnector 3. Is formed on the first surface 3a side of the interconnector 3, and the air circulation portion 31 in which the depressed air flows, and the fuel circulation portion in which the depressed fuel flows on the second surface 3b side. 32 is formed.

  Further, a seal member 85 for preventing the air flowing through the air circulation portion 31 and the fuel flowing through the fuel circulation portion 32 from leaking to the outside is disposed on the side surface 1w of the stack in which the cells 2 and the interconnectors 3 are stacked. It can be set as the structure to do. As the seal member 85, a member formed of a composite material in which a porous aggregate (porous portion) is impregnated with low-melting glass can be used. Further, the ceramic 86 may be bonded to the outside of the seal member 85. In a high temperature state in the vicinity of the operating temperature of the fuel cell 1, the glass in the seal member 85 is softened, so that the sealing performance can be ensured. On the other hand, the thermal stress can use the open efficiency by the softened glass, but the stress applied to the cell 2 can be reduced by receiving the porous portion as the aggregate. In addition, a glass joint may be disposed on the joint surface between the cell 2 and the interconnector 3.

  The operation of the fuel cell 1 will be described with reference to FIGS. 18 (a) and 18 (b). As shown in FIG. 18 (a), the adhesion between the front and back surfaces of the outer peripheral portion of the cell 2 and the first surface 3a and the second surface 3b of the outer peripheral portion of the interconnector 3 is different depending on the temperature. At normal temperature that is not in operation, a gap 63 is formed between the front and back surfaces of the outer peripheral portion of the cell 2 and the first and second surfaces 3a and 3b of the outer peripheral portion of the interconnector 3.

  Then, as shown in FIG. 18B, the gap 63 disappears due to the difference in thermal expansion at the operating temperature, and the surfaces of the cell 2 and the interconnector 3 are brought into close contact with each other to form the thermal expansion seal portion 64. Therefore, in this embodiment, the cell 2 and the interconnector 3 are flow path forming members, and the thermal expansion seal portion 64 formed with improved adhesion between the flow path forming members circulates in the stack. Prevent air and fuel from leaking out.

  As described above, the flow path forming member that forms the flow path of air and fuel in the stack is not firmly fixed at room temperature, but has a slight gap 63, so that heat generated by rapid temperature rise is generated. A low stress stack structure can be obtained without accumulating stress in the stacking direction. Furthermore, the sealing performance can be ensured at the operating temperature due to the difference in thermal expansion of each flow path forming member.

  The above-described cooling method and solid oxide fuel cell system that cools to a set temperature with nitrogen gas can also be applied to the fuel cell 1 described with reference to FIGS. 10 to 14 and FIGS. 16 to 18. . Furthermore, the cooling method and the solid oxide fuel cell system described above can be applied not only to the fuel cell 1 of the embodiment described above but also to a fuel cell that is easily damaged by thermal stress.

  By the way, it is not preferable to increase the number of stacked cells 2 to cope with further increase in output and voltage. The reason is that if the number of stacks of power generation cells increases, it is considered that there is a limit from the viewpoint of ensuring reliability at the connection part in the stack and the gas usage rate. The desirable number of stacks is about 10 layers. Therefore, it is desirable to arrange a plurality of stacks for high output and high voltage.

  15A and 15B show an embodiment of the fuel cell 1 in which a plurality of power generation cells 70 are arranged. In the fuel cell 1 shown in FIGS. 15A and 15B, a power generation cell 70 in which the cells 2 and the interconnectors 3 are stacked is accommodated in a case 72 by being insulated by a heat insulating portion 71. The power generation cell 70 is used. The heat insulating part 71 may be vacuum heat insulation or heat insulation using a heat insulating material. In FIG. 15B, two power generation cells 70 are thermally insulated and accommodated in a case 72 by a heat insulating portion 71.

  By having a plurality of stacks (power generation cells 70), even if a failure occurs in one stack, it is possible to ensure the output of the entire system by increasing the amount of fuel supplied to the remaining stack. Also, from the viewpoint of rapid start-up, it is sufficient to prepare and respond to a robust stack for obtaining output during rapid start-up, and during steady operation, a separately prepared high-output stack can be operated. By preparing a stack according to the characteristics separately, a high-performance fuel cell system as a whole system can be obtained. With such a configuration, it is possible to increase the output and voltage, and it is possible to apply not only to portable electronic devices but also to larger electronic devices.

  The present invention described above can be applied to various fuel cells having thermal shock resistance against rapid activation. For example, the present invention can also be applied to a fuel cell in which a solid electrolyte is made of a proton conductor. Examples of proton conductors include phosphate-based proton conductors (operation temperature: 150 to 350 ° C.). Therefore, the electrolyte made of the solid oxide used in the solid oxide fuel cell may be appropriately selected depending on the operating temperature of the fuel cell, and the ions conducted for the solid electrolyte are not limited to oxygen ions. .

  The solid oxide fuel cell of the present invention can be reduced in size and thickness, has excellent electrical connection between the cell and the interconnector, and is a battery for portable electric devices such as mobile phones and notebook PCs. Can be used as

It is a partial perspective view which shows one Embodiment of the fuel cell of this invention. It is sectional drawing in the cross section A of FIG. FIG. 3 is a partially enlarged view of FIG. 2. It is a figure explaining joining of an interconnector and a cell. It is a figure which shows the assembly of a fuel cell. It is a figure explaining adhesion with an interconnector and a gas supply pipe at the time of operation temperature. 1 is a block diagram showing a solid oxide fuel cell system. It is a flowchart explaining the cooling method of this invention. It is a figure which shows embodiment of a circular fuel cell. It is a perspective view which shows other embodiment of the fuel cell which can provide the cooling method of this invention. It is a perspective view which shows the assembly of a fuel cell. It is sectional drawing which shows an interconnector. It is a figure explaining the combination of an interconnector and a cell. It is a figure explaining circulation of fuel and air. It is a figure which shows embodiment which arranged the several electric power generation cell. It is a perspective view which shows other embodiment of a fuel cell. It is sectional drawing of the fuel cell shown in FIG. It is a figure explaining the action | operation of the fuel cell shown in FIG.

Explanation of symbols

1: fuel cell (stack), 1w: side surface, 2: cell, 3: interconnector, 3a: first surface, 3b: second surface, 7: gas supply pipe, 7a: air supply / exhaust hole, 11: electrolyte layer, 12: fuel electrode layer, 13: air electrode layer, 20: housing part, 20a: first housing part, 20b: second housing part, 23: bottom surface part, 24: peripheral wall part, 25: step part, 26: extension Step part 28: Connector through hole 29: Seal part 30: Thermal expansion seal part 31: Air circulation part 32: Fuel circulation part 58: Gap (between interconnector and gas supply pipe) 59: ( 61) Brazing material, 64: Thermal expansion seal part, 65: Temperature sensor, 66: Control part, 67: Air supply part, 68: Fuel supply part, 70: Power generation cell, 71: Heat insulation part 72: Case, 85: Seal member, 86: Ceramic, 100: Solid Oxide fuel cell system.

Claims (12)

A cell having an electrolyte layer, a fuel electrode layer formed on the electrolyte layer, and an air electrode layer formed on a surface of the electrolyte layer opposite to the fuel electrode layer;
An interconnector that arranges the cells on the first surface side which is one surface and the second surface side which is the other surface;
A stack in which the cells and the interconnector are alternately stacked is formed,
Further, the flow path forming members that form the air and fuel flow paths in the stack have different adhesive properties depending on the temperature, and the difference in thermal expansion between the flow path forming members at the operating temperature causes a difference between the flow path forming members. Adhesion is improved and a thermal expansion seal is formed,
The thermal expansion seal part is a solid oxide fuel cell that prevents the air and the fuel flowing through the stack from leaking to the outside. The interconnector has a passage portion for supplying and exhausting the fuel and air to and from each electrode of the cell, and an outer peripheral portion, and a through hole that communicates with the passage portion and penetrates in the height direction.
The cell and the interconnector are alternately stacked, and a gas supply pipe having a supply / exhaust hole for supplying / exhausting the fuel or air to the passage portion is provided with a gap in the through hole. The stack structure is formed;
2. The solid oxide form according to claim 1, wherein the gap is eliminated at the operating temperature, and the outer peripheral surface of the gas supply pipe and the inner peripheral surface of the through hole are in close contact to form the thermal expansion seal portion. Fuel cell.   3. The solid oxidation according to claim 2, wherein the outer peripheral surface of the gas supply pipe and the inner peripheral surface of the through hole are caulked and adhered to each other at the operating temperature due to a difference in thermal expansion between the gas supply pipe and the interconnector. Physical fuel cell. With the outer periphery of the cell sandwiched between the first surface and the second surface of the outer periphery of the interconnector, the cell and the interconnector are alternately stacked to form the stack structure,
On the first surface side of the interconnector, an air circulation portion through which air flows, and a fuel circulation portion through which fuel flows is formed on the second surface side,
Furthermore, the adhesion between the front and back surfaces of the outer peripheral portion of the cell and the first and second surfaces of the outer peripheral portion of the interconnector varies depending on the temperature, and the adhesion due to the difference in thermal expansion at the operating temperature. The solid oxide fuel cell according to claim 1, wherein the thermal expansion seal portion is formed by improvement.   A seal member for preventing leakage of the air flowing through the air circulation portion and the fuel flowing through the fuel circulation portion to the outside is disposed on a side surface of the stack in which the cells and the interconnector are stacked. The solid oxide fuel cell according to claim 4.   The solid oxide fuel cell according to claim 5, wherein the seal member is formed of a composite material in which a porous aggregate is impregnated with glass.   The solid oxide fuel cell according to claim 5 or 6, wherein a ceramic is bonded to the outside of the seal member. A cell having an electrolyte layer, a fuel electrode layer formed on the electrolyte layer, and an air electrode layer formed on a surface opposite to the fuel electrode layer on the electrolyte layer; A solid oxide fuel cell comprising: an interconnector that arranges the cells on one surface side and a second surface side that is the other surface; and a stack in which the cells and the interconnector are alternately stacked. Cooling method,
A solid oxide fuel that cools by supplying hydrogen gas to the stack from an operating temperature to a preset temperature that is lower than the operating temperature and higher than room temperature when the solid oxide fuel cell is stopped. Battery cooling method.   The method for cooling a solid oxide fuel cell according to claim 8, wherein air is supplied to the stack to be cooled below the set temperature.   The method for cooling a solid oxide fuel cell according to claim 8 or 9, wherein the set temperature is in a range of 300 ° C or higher and 500 ° C or lower. A cell having an electrolyte layer, a fuel electrode layer formed on the electrolyte layer, and an air electrode layer formed on a surface opposite to the fuel electrode layer on the electrolyte layer; A solid oxide fuel cell comprising: an interconnector that arranges the cells on one surface side and a second surface side that is the other surface; and a stack in which the cells and the interconnector are alternately stacked. When,
An air supply unit for supplying air to the solid oxide fuel cell;
A fuel supply unit for supplying fuel to the solid oxide fuel cell;
A temperature sensor for measuring the temperature of the solid oxide fuel cell;
A control unit configured to control the fuel supply unit to supply hydrogen gas to the stack to cool the solid fuel cell measured by the temperature sensor from an operating temperature to a predetermined set temperature; and
A solid oxide fuel cell system.   12. The solid oxide fuel cell system according to claim 11, wherein the control unit controls the air supply unit to supply air to the stack for cooling below the set temperature.

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