JP2013257953A - Solid oxide fuel cell and method for assembling solid oxide fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell that allows a stack to be evenly pressed in a lamination direction of cells in a low-cost and easy manner, and to provide a method for assembling the solid oxide fuel cell.SOLUTION: A spherical member 5 is provided between an upper member 4 and a pressing member 6. Even when the pressing member 6 is pressed at an angle to a lamination direction of cells 30, for example, the upper member 4 and the pressing member 6 are in contact with a spherical surface of the spherical member 5, and the upper member 4 is thus pressed in the lamination direction of the cells 30. Therefore, the stack 3 is allowed to be evenly pressed in the lamination direction of the cells 30, and that in a low-cost manner without using springs or bellows.

Description

  The present invention relates to a solid oxide fuel cell, and more particularly to a solid oxide fuel cell that presses a stack in which a single cell and a housing member that houses the single cell are stacked.

  In recent years, high efficiency can be obtained regardless of the size of the scale, and therefore, fuel cells have attracted attention as power generation means used in next-generation cogeneration systems (see, for example, Non-Patent Document 1). A fuel cell is a battery that uses a chemical reaction between an oxidant gas such as oxygen and a fuel gas such as hydrogen. A fuel cell is composed of a single cell with an electrolyte layer sandwiched between an anode called an air electrode and a cathode called a fuel electrode. A plurality of these are used in an overlapping manner. The electric voltage obtained in one set of cells (single cell) is about 0.7 [V], but it is possible to supply a desired voltage by using a plurality of single cells in an overlapping manner. . Such fuel cells include a solid polymer type using a polymer material for the electrolyte layer, and a solid oxide type using an oxide such as ceramics for the electrolyte layer.

  The polymer electrolyte fuel cell has an operating temperature of about 90 [° C.] at most, and can be applied to automobile and household cogeneration systems. On the other hand, the solid oxide fuel cell is characterized in that the operating temperature is as high as 600 [° C.] or higher and the power generation efficiency is as high as 45% or higher. For this reason, a solid oxide fuel cell with a stack structure in which a plurality of single cells are combined has the advantage that a more efficient cogeneration system can be constructed by combining turbine power generation, etc. Expected.

  By the way, in order to obtain a practical output in a solid oxide fuel cell, it is necessary to connect a plurality of single cells in series or in parallel. At this time, each unit cell is electrically connected in a state where the fuel gas supplied to the fuel electrode side of each unit cell and the oxidant gas supplied to the air electrode side are not mixed. Thus, in order to make an electrical connection in a state where mixing of gases is prevented, a member made of a material that does not transmit gas and has high electrical conductivity is used. This member is called a separator or an interconnector (hereinafter referred to as “interconnector”). In general, a single cell is sandwiched between two interconnectors that form a pair. One cell is constituted by such a pair of interconnectors and a single cell. A stack is formed by stacking a plurality of these cells. At this time, the pair of interconnectors and the single cell are overlapped along the cell stacking direction.

  In recent years, a metal material can be used for an interconnector due to the low temperature operation of the power generation temperature. Metal interconnectors are more workable than ceramic interconnectors and have high electrical and thermal conductivity, but there is a problem of forming an oxide film with low electrical conductivity on the surface in a high-temperature oxidizing atmosphere. is there. Therefore, recently, ferritic heat resistant stainless steel containing about 16 to 24% of Cr tends to be used.

  Such a solid oxide fuel cell includes a cylindrical type and a flat plate type depending on the shape of a single cell. Among these, in the flat solid oxide fuel cell, as one method for obtaining a high output, by pressing the stack in the cell stacking direction, the contact between the interconnector and the single cell is improved and the resistance due to the contact is increased. Has been done to reduce. In order to reduce the resistance due to contact in this way, it has also been proposed to provide a current collector between the interconnector and the single cell. However, even when this current collector is provided, the stacking is performed as described above. A higher output can be obtained by pressing to improve the contact between the interconnector, current collector and single cell.

  As a method for pressing the stack in this way, a method is proposed in which a spring or a bellows is used, or one of the pair of plates sandwiching the top and bottom of the stack is tightened with a screw toward the other plate.

By Tagawa Hiroaki, Solid Oxide Fuel Cell and Global Environment, Agne Jofu Co., Ltd. 25-P. 30, issued on June 20, 1998

  However, the above method has the following problems.

  First, in the method using a spring or bellows, it is difficult to reduce the cost because the spring and bellows that can be used in a high temperature environment of 600 ° C. or higher are expensive.

  Also, with the method of tightening with screws, the friction coefficient on the screw seating surface is often not the same for each screw, so even if each screw is tightened with the same torque, the tightening amount of each screw will be different. The plate to be tightened is pressed obliquely with respect to the stacking direction of the cells of the stack. Then, the contact surfaces between the single cells and the interconnectors cannot be pressed uniformly, so that good contact between the single cells and the interconnectors cannot be realized, and as a result, high output is difficult.

  Therefore, an object of the present invention is to provide a solid oxide fuel cell and a method for assembling the solid oxide fuel cell that can easily press the stack uniformly in the cell stacking direction at low cost.

  In order to solve the above-described problems, a solid oxide fuel cell according to the present invention includes a plate-shaped first member, a fuel electrode, an electrolyte composed of a solid oxide disposed on the fuel electrode, and A stack in which a plurality of cells including a single cell made of an air electrode disposed on the electrolyte and a housing member housing the single cell are stacked on the first member, and a plate shape disposed on the stack A second member, a third member disposed on the second member above the stack, and a plate-shaped fourth member disposed on the third member apart from the second member. And a fifth member that presses the fourth member toward the first member. The third member has a spherical contact surface with at least one of the second member and the fourth member. It is characterized by comprising.

In the solid oxide fuel cell, the fifth member is spaced from the stack and is suspended from the first member, and a plurality of shaft members whose open ends penetrate the second member and the third member; You may make it comprise from the pressing member which is provided in the other end side of each shaft member, and presses a 3rd member toward the one end side of the said shaft member along a shaft member.
Here, the housing member and the shaft member may be made of a material having a smaller coefficient of thermal expansion than the second member, the third member, and the fourth member.
The housing member and the shaft member are made of a material having a first value thermal expansion coefficient, and the second member and the fourth member have a second value thermal expansion coefficient larger than the first value. The third member may be made of a material having a thermal expansion coefficient with a third value larger than the second value.

In the above solid oxide fuel cell, at least one of the second member and the fourth member has a recess formed in the central portion, and the third member has a spherical surface disposed on the recess. You may be made to do.
Here, the third member may be formed of a sphere.

  In addition, a method for assembling a solid oxide fuel cell according to the present invention includes a fuel electrode, an electrolyte made of a solid oxide disposed on the fuel electrode, and a single cell made of an air electrode disposed on the electrolyte. A first step of disposing a stack in which a plurality of cells including an accommodating member accommodating the single cell and a cell are stacked on the plate-like first member, and a plate-like second member being arranged on the stack A third step in which the third member is disposed on the second member above the stack, and the plate-like fourth member is separated from the second member. A fourth step disposed on the first member, and a fifth step for pressing the fourth member toward the first member, wherein the third member comprises the second member and the fourth member. The contact surface with at least one of the members is a spherical surface.

  According to the present invention, a plate-shaped first member, a stack in which a single cell and a housing member are stacked on the first member, and a plate-shaped second member disposed on the stack, , A plate-like fourth member disposed away from the second member, and a second member and a fourth member disposed between the second member and the fourth member. With the configuration in which a third member having a spherical contact surface with at least one of the first member and a fifth member that presses the fourth member toward the first member is provided, for example, the fourth member is Even when pressed from a direction oblique to the cell stacking direction, at least one of the second member and the fourth member is in contact with the spherical surface of the third member. Pressed in the direction. Thereby, the stack can be pressed uniformly in the stacking direction. In addition, since the stack can be uniformly pressed in the stacking direction without using a spring or a bellows, low cost can be realized.

FIG. 1 is a plan view schematically showing a configuration of a solid oxide fuel cell according to the present invention. 2 is a cross-sectional view taken along the line II of FIG. FIG. 3 is a cross-sectional view of an essential part schematically showing the configuration of a single cell. FIG. 4 is a cross-sectional view of an essential part schematically showing the configuration of the cell. FIG. 5 is a diagram showing experimental results.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Configuration of solid oxide fuel cell]
As shown in FIGS. 1 and 2, the solid oxide fuel cell 1 according to the present embodiment includes a lower member 2, a stack 3 disposed on the lower member 2, and a stack 3 disposed on the stack 3. The upper member 4 provided, the spherical member 5 disposed on the upper member 4, the pressing member 6 disposed on the spherical member 5 in a state of being separated from the upper member 4, and one end of the lower member 2 The other end of the shaft member 7 passes through the upper member 4 and the pressing member 6 and is suspended from the plane of the lower member 2. And a nut 8. An insulating member 9 is disposed between the lower member 2 and the stack 3. Similarly, an insulating member 10 is disposed between the stack 3 and the upper member 4.

<Configuration of lower member>
The lower member 2 is formed in a substantially rectangular plate shape in plan view, and its outer shape is larger than the planar shape of the stack 3. Holes 21 are formed near the four corners of the upper surface of the lower substrate 2. A screw for fixing the shaft member 7 is formed on the inner peripheral surface of the hole 21. The lower member 2 is made of, for example, ferritic stainless steel such as SUS430. Such a lower member 2 corresponds to a first member.

<Stack configuration>
As shown in FIG. 2, the stack 3 has a configuration in which a plurality of cells 30 are stacked in order to obtain a practical output. As shown in FIGS. 3 and 4, each cell 30 is disposed so as to face a disk-shaped single cell 31 and a fuel electrode 311 (to be described later) of the single cell 31, and supplies fuel gas to the fuel electrode 311 and fuel. A plate-shaped fuel electrode interconnector 32 electrically connected to the electrode 311 and an air electrode 313 (to be described later) of the single cell 31 are disposed opposite to each other, and an oxidant gas is supplied to the air electrode and the air electrode 313 is electrically connected to the air electrode 313. And a plate-shaped air electrode interconnector 33 connected to the. The outer shape of the cell 30 is smaller than the planar shape of the lower member 2 and is smaller than the region surrounded by the holes 21 formed at the four corners of the upper surface of the lower member 2. Here, the fuel electrode interconnector 32 and the air electrode interconnector 33 correspond to housing members. Such a cell 30 functions as a part of the stack 3 in which a plurality of the cells 30 are stacked.

  Further, the cell 30 has a disk-shaped fuel electrode side current collector 34 disposed at the center of the upper surface of the fuel electrode interconnector 32 and the single cell 11 disposed on the upper surface, and the fuel electrode interconnector 32. The single cell 31 and the fuel electrode side current collector 34 are disposed at predetermined positions by accommodating the single cell 31 and the fuel electrode side current collector 34 in the opening formed in the central portion. A ring-shaped cell holder 35, an electrolyte 312 (to be described later) of the single cell 31, a ring-shaped seal member 36 disposed on the upper surface of the cell holder 35, and a ring-shaped insulating member 37 disposed on the upper surface of the seal member 36. And a disk-shaped air electrode side current collector 38 provided on the upper surface of the single cell 31 and provided with the air electrode interconnector 33 on the upper surface. These components are brought into close contact with adjacent components by pressing the fuel electrode interconnector 32 and the air electrode interconnector 33 toward each other.

  In such a cell 30, the fuel electrode interconnector 32, the air electrode interconnector 33, the cell holder 35, the seal member 36, and the insulation are provided around the single cell 31 in the planar direction of the fuel electrode interconnector 32 and the air electrode interconnector 33. A plurality of through holes penetrating in the stacking direction of the member 37 are formed. These through-holes provide a fuel gas manifold 39 to which fuel gas is supplied from the outside, an oxidant gas manifold 40 to which oxidant gas is supplied from the outside, and unreacted fuel gas that has not been oxidized by the single cell 31 to the outside. An exhaust gas manifold (not shown) for discharging and an unreacted oxidant gas manifold for discharging unreacted oxidant gas to the outside in the single cell 31 are configured.

<Single cell configuration>
Here, as shown in FIG. 3, the unit cell 31 has a fuel electrode 311 formed in a disk shape, and an electrolyte 312 having a shape equivalent to the fuel electrode 311 and formed on the upper surface of the fuel electrode 311. The air electrode 313 is formed in a disk shape whose outer shape is smaller than that of the electrolyte 312 and is formed on the upper surface of the electrolyte 312. Here, a current collecting layer 314 having a shape equivalent to that of the air electrode 313 is provided on the upper surface of the air electrode 313.

The fuel electrode 311 includes a metal Ni and an electrolyte 312 such as nickel-added yttria stabilized zirconia (Ni-YSZ), nickel-added samaria stabilized zirconia (Ni-SSZ), nickel-added scandia stabilized zirconia (Ni-ScSZ), and the like. It is composed of a mixture with constituent materials.
The electrolyte 312 includes, for example, scandia-stabilized zirconia (ScSZ), yttria-stabilized zirconia (YSZ), samaria-stabilized zirconia (SSZ), cobalt-added lanthanum gallate oxide (LSGMC), and the like.
The air electrode 313 includes, for example, lanthanum nickel ferrite (LNF), lanthanum manganate (LSM), lanthanum strontium cobaltite (LSC), lanthanum strontium cobaltite ferrite (LSCF), lanthanum strontium ferrite (LSF), samarium strontium cobaltite ( SSC).
The current collecting layer 314 is composed of, for example, a mixture of lanthanum nickel ferrite (LNF) and LaCoO ₃ (LC).

≪Interconnector configuration≫
The fuel electrode interconnector 32 is formed in a substantially rectangular plate shape in plan view. The fuel electrode interconnector 32 includes a space extending in the plane direction, one end including a fuel gas flow path 32a connected to the fuel gas manifold 39, and a space extending in the plane direction, and one end of the exhaust gas. An exhaust gas passage (not shown) connected to a manifold (not shown) is formed. In addition, a fuel gas supply part 32b having a plurality of grooves and connected to the other end of the fuel gas flow path 32a is formed at the center of the upper surface of the fuel electrode interconnector 32. Such a fuel electrode interconnector 32 is configured by laminating a plurality of thin plates each having a substantially rectangular shape in a plan view pressed into a predetermined shape.

  The air electrode interconnector 33 is formed in a substantially rectangular plate shape in plan view. The air electrode interconnector 33 is composed of a space extending in the plane direction, one end of which is composed of an oxidant gas flow path 33a connected to the oxidant gas manifold 40, and a space extending in the plane direction. And an unreacted air flow path (not shown) connected to the unreacted gas manifold. In addition, an oxidant gas supply unit 33b is formed at the center of the lower surface. The oxidant gas supply unit 33b includes a plurality of grooves and is connected to the other end of the oxidant gas flow path 33a. Such an air electrode interconnector 33 is configured by laminating a plurality of thin plates each having a substantially rectangular shape in a plan view pressed into a predetermined shape.

  Here, the fuel electrode interconnector 32 and the air electrode interconnector 33 are preferably made of a material having a thermal expansion coefficient equivalent to that of the shaft member 7. In the present embodiment, heat resistant stainless steel is used as the material for the fuel electrode interconnector 32 and the air electrode interconnector 33.

≪Configuration of other members in the stack≫
The fuel electrode side current collector 34 has a high electronic conductivity such as a metal such as platinum, silver, gold, palladium, iridium and rhodium, a mesh or non-woven fabric made of a fine wire of a ferritic heat-resistant alloy, an expanded metal, a foamed metal, etc. 600 Consists of materials that are chemically stable at ~ 1000 ° C.

  The cell holder 35 is made of, for example, a ferrite heat resistant alloy containing about 16 to 25% of chromium. Inside the cell holder 15, the fuel electrode side current collector 14, the fuel electrode 111 and the electrolyte 112 of the single cell 11 are accommodated, and a gap between these peripheral surfaces and the inner surface of the cell holder 15 is equivalent to the seal member 16. A gap member 15a made of a material is provided.

  The sealing member 36 is made of, for example, a glass material having a softening point near the operating temperature, such as borosilicate glass.

  The insulating member 37 is made of an insulating material such as ceramic that is insulative even at a high temperature such as alumina, or mica.

  The air electrode side current collector 38 is made of a paste material containing a material such as a metal such as platinum, silver, gold, palladium, iridium, or rhodium, or a fine wire of a ferrite heat-resistant alloy. This paste material is applied on the current collecting layer in advance before the initial operation of the solid oxide fuel cell 1, and the air electrode interconnector 33 is disposed thereon, so that the temperature of the paste material can be increased during the initial operation. A good electrical connection is formed. Further, by applying pressure to the contact surface between the air electrode interconnector 33 and the single cell 31, an even better electrical connection can be obtained.

<Configuration of upper member>
The upper member 4 is formed in a substantially rectangular plate shape in plan view equivalent to the lower member 2, and holes 41 penetrating in the thickness direction are formed in the vicinity of the four corners. The holes 41 are formed in a one-to-one correspondence with the holes 21 of the lower member 2, and are aligned with the corresponding holes 21 when the lower member 2 and the upper member 4 are arranged to face each other in parallel. Will be located. A spherical recess 42 corresponding to the shape of the spherical member 5 is formed on the upper surface of the upper member 4. The recess 42 is formed on the upper surface of the upper member 4, but is preferably formed in a region above the stack 3 when the upper member 4 is disposed on the stack 3. It is more desirable to form. In the present embodiment, the recess 42 is formed at the center of the upper member 4.

  Such an upper member 4 is preferably made of a material that is equivalent to or larger in thermal expansion coefficient than the fuel electrode interconnector 32, the air electrode interconnector 33, and the shaft member 7. In the present embodiment, ferritic stainless steel such as SUS430 is used. Further, the upper member 4 has such a rigidity that deformation can be ignored even in an assembled state as will be described later. Furthermore, the thickness of the upper member 4 is desirably at least 10 [mm] or more. Such an upper member 4 corresponds to a second member.

<Configuration of spherical member>
The spherical member 5 is formed in a spherical shape whose diameter is smaller than the width of the upper member 4. Such a spherical member 5 is preferably made of a material having a larger coefficient of thermal expansion than the upper member 4. Specifically, austenitic stainless steel is desirable, and among them, SUS304 and SUS310 are more desirable. In particular, SUS310 is desirable because of its high heat resistance. Further, the spherical member 5 has such a rigidity that deformation can be ignored even in an assembled state as will be described later. Such a spherical member 5 corresponds to a third member.

<Configuration of holding member>
The pressing member 6 is formed in a substantially rectangular plate shape in plan view equivalent to the lower member 2 and the upper member 4, and holes 61 penetrating in the thickness direction are formed in the vicinity of the four corners. The through hole 61 is formed corresponding to the through hole 61 of the upper member 4. Therefore, when the upper member 4 and the pressing member 6 are arranged to face each other in parallel, the corresponding holes 41 and 61 are located on the same straight line. At this time, as described above, when the lower member 2 and the upper member 4 are also arranged to face each other in parallel, the corresponding holes 21, 41 and 61 are located on the same straight line. A spherical recess 62 corresponding to the shape of the spherical member 5 is formed on the lower surface of the pressing member 6. The concave portion 62 is formed on the lower surface of the pressing member 6, but is desirably formed in a region above the stack 3 when the pressing member 6 is disposed opposite to the upper member 4. It is more desirable to form. In the present embodiment, the recess 62 is formed at the center of the lower surface of the pressing member 62. Therefore, when the upper member 4 and the pressing member 6 are disposed to face each other, the recess 62 is disposed to face the recess 42 of the upper member 4. Such a pressing member 6 corresponds to a fourth member.

  As with the upper member 4, such a pressing member 6 is preferably made of a material having a larger coefficient of thermal expansion than the shaft member 7. In the present embodiment, ferritic stainless steel such as SUS430 is used. In addition, the pressing member 6 has such a rigidity that deformation can be ignored even in an assembled state as will be described later.

<Configuration of shaft member>
The shaft member 7 is formed in a rod shape, a screw that is screwed into the hole 21 of the lower member 2 is formed at one end, and a screw that is screwed into the nut 8 is formed at the other end. Such a shaft member 7 is preferably SUS410 or SUS430, which is equivalent to the fuel electrode interconnector 32 and the air electrode interconnector 33, equivalent to the upper member 4, or has a thermal expansion coefficient of about 11 × 10 ⁻⁶ [/ ° C.]. . In the present embodiment, a material having a smaller thermal expansion coefficient than that of the upper member 4 is used as the material of the shaft member 7.

<Nut configuration>
The nut 8 is composed of a known hex nut, and is screwed to the other end of each shaft member 7. Such a nut 8 corresponds to a pressing member.

<Configuration of insulating member>
The insulating members 9 and 10 are formed in a planar shape equivalent to the stack 3. Such insulating members 9 and 10 are made of mica, magnesia, alumina, or the like. Among these, mica is desirable because of its low cost. Further, the insulating members 9 and 10 are formed to have a thickness of at least 1 [mm] in order to more reliably insulate the lower member 2 or the upper member 4.

[Assembly method of solid oxide fuel cell]
Next, a method for assembling the solid oxide fuel cell according to the present embodiment will be described.

  First, after placing the lower member 2 on the ground, base, or the like, the shaft member 7 is screwed into each hole 21 of the lower member 2. As a result, the shaft member 7 is suspended from the lower member 2.

  When the shaft member 7 is fixed, the insulating member 9 is placed in a region surrounded by the shaft member 7 on the upper surface of the lower member 2, and then the stack 3 is disposed on the insulating member 9. Here, the stack 3 is disposed on the insulating member 9 in an assembled state as shown in FIG. The stack 3 is disposed on the insulating member 9 so that the stacking direction of the cells 30 and the direction perpendicular to the upper surface of the lower member 2, that is, the vertical direction coincide. At this time, the shaft member 7 and the stack 3 are separated from each other. An insulating member 9 is provided between the lower member 2 and the stack 3. Therefore, the lower member 2 and the stack 3 are electrically insulated.

  When the stack 3 is disposed, the insulating member 10 is placed on the stack 3, and then each hole 41 of the upper member 4 is inserted into the other end (open end) of the corresponding shaft member 7. It is disposed on the insulating member 10. At this time, since the shaft member 7 is inserted into the hole 41 of the upper member 4, the moving direction of the upper member 4 is the direction in which the shaft member 7 extends, that is, the direction perpendicular to the lower member 2 (vertical direction). ). Further, the upper member 4 and the lower member 2 are substantially parallel and perpendicular to the stacking direction of the cells 30 of the stack 3. Further, since the insulating member 10 is provided between the stack 3 and the upper member 4, the stack 3 and the upper member 4 are electrically insulated.

  When the upper member 4 is disposed, the spherical member 5 is disposed on the concave portion 42 on the upper surface of the upper member 4. Here, by providing the recess 42, the spherical member 5 can be prevented from moving on the upper member 4, and the spherical member 5 can be disposed at a predetermined position on the upper member 4.

  When the spherical member 5 is disposed, the pressing member 6 is disposed on the spherical member 5 after each hole 61 of the pressing member 6 is inserted into the other end of the corresponding shaft member 7. At this time, the spherical member 5 and the pressing member 6 are in contact with a recess 62 formed on the lower surface of the pressing member 6. Further, the movement direction of the pressing member 6 is regulated in the vertical direction because the shaft member 7 is inserted into the hole 61 of the pressing member 6.

  When the pressing member 6 is disposed, the nut 8 is screwed to the other end of each shaft member 7, and the nut 8 is tightened and fixed with a predetermined torque. Thereby, the solid oxide fuel cell 1 is assembled.

  At this time, the pressing member 6 is pressed by the nut 8 along the extending direction of the shaft member 7 and toward the lower member 2, that is, vertically downward. The pressing member 6 is connected to the lower member 2 via a nut 8 and a shaft member 7. Further, the spherical member 5 is in contact with the lower surface of the pressing member 6, and the upper member 4 is in contact with the side of the spherical member 5 opposite to the pressing member 6. A stack 3 is disposed between the lower member 2 and the upper member 4 via an insulating member 9 or an insulating member 10. Therefore, by tightening the nut 8, the stack 3 is pressed in the direction in which the lower member 2 and the upper member 4 approach each other, that is, pressed in the vertical vertical direction. At this time, in the stack 3, the stacking direction of the cells 30, that is, the stacking direction of the single cell 31, the air electrode interconnector 32, the fuel electrode interconnector 33, and the like is the moving direction (vertical direction) of the lower member 2 and the upper member 4. Is consistent with Accordingly, the air electrode interconnector 32 and the fuel electrode interconnector 33 that are paired are pressed in a direction in which they approach each other, so that the contact between the components of the stack 3, specifically, the fuel electrode interconnector 31 and the fuel electrode side Between the current collector 34, between the fuel electrode side current collector 34 and the fuel electrode 311 of the single cell 31, between the air electrode interconnector 32 and the air electrode side current collector 38, and between the air electrode side current collector Since the contact between the current collector 38 and the current collecting layer 314 of the single cell 31 is improved, a higher output can be obtained.

  Further, the pressing force applied to the pressing member 6 by the nut 8 is transmitted to the upper member 4 through the spherical member 5. Here, the surface of the spherical member 5 on the side of the pressing member 6 is in sliding contact with the recess 62 on the lower surface of the pressing member 6. The surface of the spherical member 5 on the upper member 4 side is in sliding contact with the concave portion 42 on the upper surface of the upper member 4. Therefore, a pressing force is applied to the upper member 4 along the extending direction of the shaft member 7, that is, the vertical direction. Thereby, the seating surface resistance of each nut 8 is different, and even if there is variation in tightening by the nut 8 and the pressing member 6 is pressed obliquely with respect to the vertical direction, the upper member 4 is vertically moved by the spherical surface of the spherical member 5. It will be pressed along the direction. Therefore, the contact surface of each component of the stack 3, specifically, the contact surface between the fuel electrode interconnector 32 and the fuel electrode side current collector 34, and the fuel electrode side current collector 34 and the fuel electrode 311 of the single cell 31. The contact surface between the air electrode interconnector 32 and the air electrode side current collector 38 and the contact surface between the air electrode side current collector 38 and the current collecting layer 314 of the single cell 3 are uniformly loaded. Therefore, the contact between these constituent materials becomes good, and as a result, high output can be realized.

  At this time, by providing the recess 42 on the upper surface of the upper member 4 and the recess 62 on the lower surface of the pressing member 6, the spherical member 5 can be prevented from moving in the space between the upper member 4 and the pressing member 6. As a result, the upper member 4 can be more reliably pressed in the vertical direction.

[Operation of solid oxide fuel cell]
Next, the power generation operation of the solid oxide fuel cell 1 assembled by the procedure as described above will be described.

  First, after heating the solid oxide fuel cell 1 to a predetermined temperature with a heater or the like, fuel gas and oxidant gas are supplied. Here, the fuel gas such as dry hydrogen passes from the fuel gas manifold 39 through the fuel gas flow path 32a and the fuel supply part 32a of the fuel electrode interconnector 32, and via the fuel electrode side current collector 34 to the single cell 31. To the fuel electrode 311. On the other hand, the oxidant gas such as air passes from the oxidant gas manifold 40 through the oxidant gas flow path 33a and the oxidant gas supply part 33b of the air electrode interconnector 33, through the air electrode side current collector 38, The air is supplied from the current collecting layer 114 of the single cell 31 to the air electrode 113. As described above, when the fuel gas and the oxidant gas are supplied to the single cell 31 at a predetermined temperature, an electrochemical reaction occurs between the fuel electrode 311 and the air electrode 313.

  In such a state, when the air electrode interconnector 33 in the upper end cell 30 of the stack 3 and the fuel electrode interconnector 32 in the lower end cell 30 are connected to the load circuit as terminals, electric power can be taken out.

  At this time, the spherical member 5 is made of a material having a higher thermal expansion coefficient than the upper member 4 and the pressing member 6. Further, the upper member 4 and the pressing member 6 are made of a material having a higher thermal expansion coefficient than that of the shaft member 7. Accordingly, when the solid oxide fuel cell 1 is heated for power generation, the spherical member 5 expands more than the upper member 4 and the pressing member 6, and therefore the force in the direction in which the upper member 4 and the pressing member 6 are separated from each other. Since the load is applied to the stack 3, the output can be improved. Further, since the upper member 4 and the pressing member 6 are expanded more than the shaft member 7, a force is applied in a direction in which the upper member 4 and the pressing member 6 approach the lower member 2 and a load is applied to the stack 3, thereby improving the output. Can be made. Furthermore, since the shaft member 7, the fuel electrode interconnector 32, and the air electrode interconnector 32 are made of materials having the same thermal expansion coefficient, the solid oxide fuel cell 1 can be heated for power generation. Since it expands similarly, damage to the solid oxide fuel cell 1 can be prevented.

  Here, FIG. 5 shows the measurement results when power is actually generated by the solid oxide fuel cell 1 according to the present embodiment. In FIG. 5, the pattern 1 shows a case where SUS430 is used for the spherical member 5, and the pattern 2 shows a case where SUS310 is used for the spherical member 5. For comparison, the case where the spherical member 5 is not provided as the pattern 3 is also shown. In this pattern 3, the upper member 4 and the pressing member 6 are in contact. FIG. 5 shows the measurement results when the stack 3 is composed of one cell 30, the fuel utilization rate is 60 [%], and the voltage is 50 [A].

  As shown in FIG. 5, when SUS430 is used for the spherical member 5 (pattern 1), the output is 34 [W], and when SUS310 is used as the spherical member 5 (pattern 2), the output is 42 [W]. It was. On the other hand, when the spherical member 5 was not used (pattern 3), the output was 28 [W]. Thus, it was confirmed that the use of the spherical member 5 improves the output as compared with the case where the spherical member 5 is not used. It was also confirmed that the output was higher when SUS310 having a large thermal expansion coefficient was used as the spherical member 5.

  As described above, according to the present embodiment, by providing the spherical member 5 between the upper member 4 and the pressing member 6, for example, the pressing member 6 is pressed obliquely with respect to the stacking direction of the cells 30. However, since the upper member 4 and the pressing member 6 are in contact with the spherical surface of the spherical member 5, the upper member 4 is pressed in the stacking direction of the cells 30. Thereby, the stack 3 can be pressed uniformly in the stacking direction of the cells 30. Further, since the stack 3 can be uniformly pressed in the stacking direction without using a spring or a bellows, a low cost can be realized.

  In this embodiment, the case where the spherical member 5 made of a spherical body is provided between the upper member 4 and the pressing member 6 has been described as an example, but the contact surface with at least one of the upper member 4 and the pressing member 6 is The member provided between the upper member 4 and the pressing member 6 is not limited to a sphere, and can be freely set as appropriate as long as it is configured from a spherical surface. can do. Therefore, for example, a member having a spherical surface such as a hemisphere or a spheroid, or a member that contacts at a point such as a cone may be provided.

  Moreover, although the case where the pressing member 6 is pressed by the shaft member 7 and the nut 8 has been described as an example in the present embodiment, the configuration for pressing the pressing member 6 is not limited to this. For example, the lower member 2 Various methods can be used freely as appropriate, such as providing a device for clamping the pressing member 6 and the pressing member 6.

  Further, in this embodiment, the case where the spherical concave portion 42 or the concave portion 62 is provided in the upper member 4 and the pressing member 6 that are in contact with the spherical member 5 has been described as an example. However, instead of these, a hole is formed. May be. Even if it does in this way, since the spherical member 5, the upper member 4, and the pressing member 6 will slidably contact and will contact | abut substantially one point, the effect equivalent to this Embodiment is implement | achieved. be able to. Needless to say, the recess 42 and the recess 62 may be omitted.

  Further, in the present embodiment, the case where the upper member 4, the spherical member 5, the pressing member 6 and the shaft member 7 are made of metal has been described as an example, but each has the thermal expansion coefficient described in the present embodiment. If it is, the material will not be limited to a metal, For example, various materials, such as ceramics, can be used.

  Further, in the present embodiment, the case where the pressing member 6 is pressed and fixed by the nut 8 has been described as an example. However, the configuration for fixing the pressing member 6 is not limited to the nut 8, and for example, caulking, clamping Various methods such as welding can be used.

  In the present embodiment, the case where the lower substrate 2, the upper substrate 4, the holding plate 6, the fuel electrode interconnector 32, and the air electrode interconnector 33 are formed in a substantially rectangular shape in plan view has been described as an example. Needless to say, the planar shape is not limited to a rectangle, and can be set as appropriate, such as a circle. Similarly, the unit cell 31 has been described by way of example in which the unit cell 31 is formed in a substantially circular shape in plan view. However, the planar shape is not limited to a circular shape, and it is needless to say that a rectangular shape or the like can be set as appropriate.

  The present invention can be applied to a solid oxide fuel cell.

  DESCRIPTION OF SYMBOLS 1 ... Solid oxide fuel cell, 2 ... Lower member, 3 ... Stack, 4 ... Upper member, 5 ... Spherical member, 6 ... Holding member, 7 ... Shaft member, 8 ... Nut, 9, 10 ... Insulating member, 21 ... Hole, 30 ... Cell, 31 ... Single cell, 32 ... Fuel electrode interconnector, 32a ... Fuel gas flow path, 32b ... Fuel gas supply part, 33 ... Air electrode interconnector, 33a ... Oxidant gas flow path, 33b ... Oxidant gas supply unit 34 ... Fuel electrode side current collector 35 ... Cell holder 36 ... Seal member 37 ... Insulating member 38 ... Air electrode side current collector 39 ... Fuel gas manifold 40 ... Oxidant gas manifold , 41 ... hole, 42 ... recess, 61 ... hole, 62 ... recess, 311 ... fuel electrode, 312 ... electrolyte, 313 ... air electrode, 314 ... current collecting layer.

Claims (7)

A plate-like first member;
A cell including a fuel cell, a single cell composed of an electrolyte composed of a solid oxide disposed on the fuel electrode, an air electrode disposed on the electrolyte, and a housing member accommodating the single cell is provided in the first embodiment. A stack of multiple layers on the member,
A plate-like second member disposed on the stack;
A third member disposed on the second member above the stack;
A plate-like fourth member disposed on the third member apart from the second member;
A fourth member that presses the fourth member toward the first member,
The solid oxide fuel cell, wherein the third member has a spherical contact surface with at least one of the second member and the fourth member. The solid oxide fuel cell according to claim 1, wherein
The fifth member is
A plurality of shaft members that are vertically suspended from the first member and spaced from the stack, and whose open ends penetrate the second member and the third member;
A solid member that is provided on the other end side of each shaft member, and that presses the third member along the shaft member toward the one end side of the shaft member. Physical fuel cell. The solid oxide fuel cell according to claim 2, wherein
The housing member and the shaft member are made of a material having a smaller coefficient of thermal expansion than the second member, the third member, and the fourth member. A solid oxide fuel cell, wherein: The solid oxide fuel cell according to claim 2 or 3,
The housing member and the shaft member are made of a material having a first value thermal expansion coefficient,
The second member and the fourth member are made of a material having a second coefficient of thermal expansion greater than the first value,
The third member is made of a material having a third coefficient of thermal expansion greater than the second value. A solid oxide fuel cell, wherein: The solid oxide fuel cell according to any one of claims 1 to 4,
At least one of the second member and the fourth member has a recess formed in a central portion,
The third member is a solid oxide fuel cell, wherein the spherical surface is disposed on the recess. The solid oxide fuel cell according to any one of claims 1 to 5,
The third member is composed of a sphere. A solid oxide fuel cell, wherein: A stack in which a plurality of cells including a fuel cell, a single cell composed of a solid oxide electrolyte disposed on the fuel electrode, and an air electrode disposed on the electrolyte, and a housing member accommodating the single cell, are stacked. A first step of disposing on a plate-like first member;
A second step of disposing a plate-like second member on the stack;
A third step of disposing a third member on the second member above the stack;
A fourth step of disposing a plate-like fourth member on the third member in a state of being separated from the second member;
A fifth step of pressing the fourth member toward the first member;
The method of assembling a solid oxide fuel cell, wherein the third member has a spherical contact surface with at least one of the second member and the fourth member.

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