JP2006331688A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell with improved drainage on the cathode electrode side and uniform surface pressure applied in the stacking direction.
A separator 14 is laminated on the anode electrode 12 side of the MEA 10 and a separator 15 is laminated on the cathode electrode 13 side, and a plurality of convex portions 31 are formed on the surface of the separator 14 facing the anode electrode 12. A plurality of convex portions 41 are disposed on the surface of the separator 15 facing the cathode electrode 13, and the maximum length in the X direction (L _AX ) of the convex portion 31 is the maximum length in the Y direction when viewed from the stacking direction. Longer than (L _AY ), the maximum length in the X direction (L _AX ) is substantially the same as an odd multiple of the maximum length in the X direction (L _CX ) of the convex portion 41, and the maximum length in the Y direction ( L _AY ) is substantially the same as the maximum length (L _CY ) of the convex portions 41 in the Y direction, and the interval between the convex portions 41 in the X direction is the maximum length (L _CX ) of the convex portions 41 in the X direction. This is the fuel cell 1 in which the protrusion 31 and the protrusion 41 are overlapped in the stacking direction.
[Selection] Figure 6

Description

  The present invention relates to a fuel cell including a separator having a plurality of protrusions formed on a surface and defining a fluid flow path by the plurality of protrusions.

  Conventionally, a general polymer electrolyte fuel cell has an electrolyte membrane made of an ion exchange membrane, an anode electrode (fuel electrode) disposed on one surface of the electrolyte membrane, and the other surface of the electrolyte membrane. A single cell is formed by a membrane-electrode assembly (MEA) consisting of an arranged cathode electrode (oxidant electrode) and separators disposed on both sides of the MEA. And a plurality of single cells are stacked to form a fuel cell stack.

  As a separator used in such a fuel cell, a concavo-convex shape is formed on the surface facing the MEA, a convex portion is in contact with the electrode, and a concave portion is a gas flow path for circulating gas. There is something to be. That is, the separator disposed on the anode electrode side supplies a fuel gas to the anode electrode by flowing a fuel gas (for example, a gas containing hydrogen) through the gas flow path, and the top surface of the convex portion is The separator in contact with the anode electrode and disposed on the cathode electrode side supplies an oxidant gas to the cathode electrode by flowing an oxidant gas (for example, a gas containing oxygen, usually air) through the gas flow path. In addition, the top surface of the convex portion is in contact with the cathode electrode. The gas channel also plays a role of discharging moisture such as generated water generated by an electrochemical reaction performed in the fuel cell to the outside.

  In the fuel cell, in order to improve the power generation characteristics, it is required to efficiently discharge the generated water to the outside from the gas flow path. Therefore, as a fuel cell separator capable of positively discharging generated water to the outside, for example, the outer shape of the gas flow path region is a line-symmetric shape, and the gas supply port and the gas discharge port are on the line-symmetric axis. Are arranged in the gas flow channel region, and the gas flow channel is arranged by the plurality of convex portions. The one with the composition which defined is introduced. In this separator, the convex portion formed on the anode electrode side and the convex portion formed on the cathode electrode side have the same shape (the cross-sectional shape perpendicular to the cell stacking direction is substantially square). (For example, refer to Patent Document 1).

In addition, a fuel cell separator is also introduced, which is composed of a composite formed by combining natural graphite powder with a thermosetting resin and has a rib portion having a predetermined shape on the surface. Also in this fuel cell separator, the rib formed on the anode electrode side and the rib formed on the cathode electrode side have the same shape (the cross-sectional shape perpendicular to the cell stacking direction is substantially square). (For example, refer to Patent Document 2).
JP 2002-117870 A JP 2004-6432 A Japanese Utility Model Publication No. 6-72159 JP-A-8-203546 JP 2004-164927 A Japanese Patent Laid-Open No. 11-176457

  However, the fuel cell separators described in Patent Document 1 and Patent Document 2 are formed on the convex portion (rib) formed on the surface (contact surface) facing the anode electrode and on the surface facing the cathode electrode. Since the protrusions (ribs) have the same shape, the cathode electrode side where there is a lot of moisture to be discharged to the outside, such as generated water, and the anode electrode side where the moisture to be discharged to the outside is relatively small A gas flow path having the same shape is formed. Therefore, a phenomenon occurs in which the drainage on the cathode electrode side is relatively lowered as compared with the anode electrode side.

  The present invention has been made in view of such circumstances, and a fuel cell including a fuel cell separator capable of improving the drainage on the cathode electrode side and making the surface pressure applied in the stacking direction uniform. The purpose is to provide.

In order to achieve this object, the present invention provides an anode electrode disposed on one surface of an electrolyte, a cathode electrode disposed on the other surface, and a surface on which the anode electrode and the electrolyte of the cathode electrode are disposed. And a separator that defines a fluid flow path by a plurality of convex portions that are respectively disposed on a surface opposite to the electrode and formed on a surface facing the electrode. The protrusions are arranged at a distance from each other in the X direction and the Y direction, which are at least two directions parallel to the surface of the separator, and are formed on the surface facing the anode electrode when viewed from the stacking direction. The maximum length in the X direction (L _AX ) is longer than the maximum length in the Y direction (L _AY ), and the maximum length in the X direction (L _AX ) is formed on the surface facing the cathode electrode. Odd multiple of maximum length (L _CX ) of convex part in X direction And the maximum length (L _AY ) in the Y direction is substantially the same as the maximum length (L _CY ) in the Y direction of the convex portion formed on the surface facing the cathode electrode, When viewed from the direction, the distance in the X direction between the protrusions formed on the surface facing the cathode electrode is substantially the same as the maximum length (L _CX ) of the protrusions in the X direction. The present invention provides a fuel cell in which a convex portion formed on an opposing surface and a convex portion formed on a surface facing the cathode electrode are overlapped in the stacking direction.

  In the fuel cell having this configuration, the fluid flow path is formed by a plurality of convex portions that are spaced apart from each other in the X direction and the Y direction, which are at least two directions parallel to the surface of the separator. The fluid (fuel gas, oxidant gas, generated water, etc.) flowing through the flow path is efficiently diverted by the convex portion, and the generated water is efficiently combined with the exhaust gas after being used in the electrochemical reaction of the fuel cell. It is discharged outside.

  Further, due to the relationship between the lengths in the X direction and the Y direction described above, the convex portion formed on the surface facing the anode electrode as viewed from the stacking direction is more than the convex portion formed on the surface facing the cathode electrode. The large area. That is, the fluid flow path on the cathode electrode side where a large amount of water to be discharged to the outside exists can be made wider than the fluid flow path on the anode electrode side. Therefore, drainage on the cathode electrode side can be further improved.

  Furthermore, since the convex portion formed on the surface facing the anode electrode and the convex portion formed on the surface facing the cathode electrode are always overlapped in the stacking direction, the surface pressure applied in the stacking direction is made uniform. be able to.

  Further, in the fuel cell according to the present invention, when viewed from the stacking direction, the interval in the X direction between the protrusions formed on the surface facing the cathode electrode is a protrusion formed on the surface facing the anode electrode. It can be made substantially the same as the space | interval of the X direction of parts.

  Further, when viewed from the stacking direction, the spacing in the Y direction between the convex portions formed on the surface facing the cathode electrode is the spacing in the Y direction between the convex portions formed on the surface facing the anode electrode. And substantially the same.

  In the fuel cell according to the present invention, the shape of the convex portion formed on the surface facing the anode electrode is not particularly limited as long as the above-described conditions are satisfied. When viewed from the side, it can be configured to be a substantially rectangular shape that is long in the X direction. Moreover, this convex part can also be made into other shapes, such as a long round shape, an ellipse shape, or a polygon long in the said X direction seeing from the said lamination direction.

  In the fuel cell according to the present invention, the shape of the convex portion formed on the surface facing the cathode electrode is not particularly limited as long as the above-described conditions are satisfied. When viewed from the top, it can be configured to be substantially square. In addition, the convex portion may have another shape such as a circle, a polygon, a rectangle, an oval, an ellipse, or the like when viewed from the stacking direction.

  Furthermore, in the fuel cell according to the present invention, the protrusion formed on the surface facing the anode electrode is substantially similar to the protrusion formed on the surface facing the cathode electrode when viewed from the stacking direction. It can also comprise so that it may become. That is, the convex portion formed on the surface facing the anode electrode can be configured to be slightly larger than the convex portion formed on the surface facing the cathode electrode. With this configuration, when the separators are stacked, even if the separators are slightly displaced in the lateral direction, this deviation can be allowed, and the protrusions formed on the surface facing the anode electrode and the cathode It is possible to maintain a state in which the convex portions formed on the surface facing the electrode are overlapped in the stacking direction. Therefore, the surface pressure applied in the stacking direction can be made more uniform.

  In the fuel cell according to the present invention, the electrolyte may be an electrolyte membrane, and a membrane-electrode assembly may be constituted by the electrolyte membrane, the anode electrode, and the cathode electrode.

  The fuel cell according to the present invention has a structure in which the anode electrode has a length relationship between a convex portion formed on the surface facing the anode electrode and a convex portion formed on the surface facing the cathode electrode, as viewed from the stacking direction. The convex portion formed on the surface facing the cathode electrode has a larger area than the convex portion formed on the surface facing the cathode electrode, so the fluid on the cathode electrode side where a large amount of water to be discharged exists. The flow path can be made wider than the fluid flow path on the anode electrode side. As a result, it is possible to improve drainage performance in the fluid channel on the cathode electrode side. In addition, since the convex portion formed on the surface facing the anode electrode and the convex portion formed on the surface facing the cathode electrode are overlapped in the stacking direction, the surface pressure in the stacking direction is made uniform. can do. As a result, a fuel cell having excellent power generation performance and reliability can be provided.

  Next, a fuel cell stack and a fuel cell according to preferred embodiments of the present invention will be described with reference to the drawings. In addition, embodiment described below is the illustration for demonstrating this invention, and this invention is not limited only to these embodiment. Therefore, the present invention can be implemented in various forms without departing from the gist thereof.

  FIG. 1 is a plan view of a separator disposed on the anode electrode side of a fuel cell according to an embodiment of the present invention, and FIG. 2 is a separator disposed on the cathode electrode side of the fuel cell according to an embodiment of the present invention. FIG. 3 is an enlarged plan view showing a part of the separator shown in FIG. 1, FIG. 4 is an enlarged plan view showing a part of the separator shown in FIG. 2, and FIG. FIG. 6 is an enlarged schematic view of a part of a single cell that is a constituent element of the fuel cell stack according to the present embodiment. FIG.

  As shown in FIGS. 1 to 6, the fuel cell 1 according to the embodiment of the present invention includes an electrolyte membrane 11, an anode electrode 12 (fuel electrode) disposed on one surface of the electrolyte membrane 11, and the electrolyte membrane 11. An MEA 10 comprising a cathode electrode 13 (oxidant electrode) disposed on the other surface is provided. A separator 14 is disposed on the anode electrode 12 side of the MEA 10, and a separator 15 is disposed on the cathode electrode 13 side. The MEA 10 and the separators 14 and 15 constitute a single cell 9, and a plurality of the single cells 9 are stacked to form a cell stacked body. A terminal 20, an insulator 21, an end are provided at both ends of the cell stacked body in the cell stacking direction. Each of the plates 22 is arranged to form a stack 23, the stack 23 is clamped in the cell stacking direction, and a fastening member 24 (for example, a tension plate, a through bolt, etc.) and a bolt 25 extending outside the stack 23 in the cell stacking direction It consists of something fixed with a nut.

  The electrolyte membrane 11 plays a role of moving hydrogen ions supplied from the fuel gas from the anode electrode 12 to the cathode electrode 13.

  The anode electrode 12 and the cathode electrode 13 are composed of, for example, a catalyst layer and a diffusion layer. The catalyst layer is disposed in contact with the electrolyte membrane 11 and includes, for example, carbon particles, a solid electrolyte, and a catalyst supported on the carbon particles. As the catalyst, for example, platinum or a platinum alloy is preferably used. When hydrogen supplied from the fuel gas reaches the catalyst layer, the hydrogen molecules are converted into two active hydrogen atoms on the surface of the catalyst. The oxidation reaction further proceeds on the catalyst surface, and two hydrogen ions and two electrons are released. The hydrogen ions permeate into the electrolyte membrane 11 described above. In this catalyst layer, by changing the blending ratio of the catalyst and the solid electrolyte, a decrease in catalyst utilization efficiency is suppressed and battery performance is improved.

  The diffusion layer is a conductor having a function of passing a fluid and a function of conducting the catalyst layer and the separator. Specifically, the diffusion layer has water permeability for moving the reaction gas supplied from the fluid flow path of the separator to the catalyst layer side.

  The separators 14 and 15 are boundaries that separate the single cells 9 from each other, and serve to prevent the single cells 9 from short-circuiting due to contact between the anode electrode 12 and the cathode electrode 13 between the adjacent single cells 9. At the same time, it plays the role of an electrical connector between adjacent single cells 9. The separators 14 and 15 are characterized by high electron conductivity, excellent corrosion resistance, and no release of metal ions in a gas atmosphere. For example, carbon, metal, or conductive resin is used as a material that satisfies these conditions.

  The separator 14 disposed on the anode electrode 12 side has a plurality of convex portions 31 formed in the power generation region of the surface 14 </ b> A facing the anode electrode 12. The plurality of convex portions 31 are formed in two directions parallel to the surface 14A of the separator 14 in the X direction (the direction indicated by the arrow X in FIGS. 1 and 3) and the Y direction (in FIGS. 1 and 3) perpendicular to the X direction. Are arranged in a state of being separated from each other in the direction indicated by the arrow Y). And these convex parts 31 have the same shape, respectively, and demarcate the fuel gas flow path 35 through which fuel gas (for example, gas containing hydrogen) distribute | circulates.

The convex portion 31 has a rectangle whose length in the X direction (L _AX ) is longer than the length in the Y direction (L _AY ) when viewed from the cell stacking direction (in plan view). Specifically, the length (L _AX ) in the X direction of the convex portion 31 is three times as long as the length (L _AY ) in the Y direction. The interval in the X direction between the convex portion 31 and the convex portion 31 adjacent to the convex portion 31 is the same as the length (L _AY ) in the Y direction, as shown in FIG. Further, the interval in the Y direction between the convex portion 31 and the convex portion 31 adjacent to the convex portion 31 is also the same as the length (L _AY ) in the Y direction, as shown in FIG.

  In addition, a fuel gas supply port 32 through which fuel gas is supplied is formed at the end of the separator 14 in the Y direction, and a fuel gas discharge port 33 through which fuel gas is discharged at the end opposite to the Y direction. Is formed. Furthermore, an oxidant gas supply port 42 to which an oxidant gas (for example, a gas containing oxygen, usually air) is supplied is formed at the end of the separator 14 in the X direction, and the end opposite to the X direction is formed. An oxidant gas discharge port 43 through which oxidant gas is discharged is formed in the part.

  The separator 15 disposed on the cathode electrode 13 side has a plurality of convex portions 41 formed in the power generation region of the surface 15 </ b> A facing the cathode electrode 13. The plurality of convex portions 41 are two directions parallel to the surface 15A of the separator 15 in the X direction (the direction indicated by the arrow X in FIGS. 2 and 4) and the Y direction (the direction indicated by the arrow Y in FIGS. 2 and 4). ) Are arranged in a state of being separated from each other. These convex portions 41 have the same shape and define an oxidant gas passage 45 through which an oxidant gas (for example, air) flows.

The convex portion 41 has a square shape whose length in the X direction (L _CX ) is the same as the length in the Y direction (L _CY ) when viewed from the cell stacking direction (in plan view). Further, the length (L _CX , L _CY ) of one side of the convex portion 41 is the same as the length (L _AY ) of the convex portion 31 in the Y direction. Accordingly, the length (L _AX ) of the convex portion 31 in the X direction described above is three times the length (L _CX ) of the convex portion 41 in the X direction.

Further, the distance in the X direction between the convex portion 41 and the convex portion 41 adjacent to the convex portion 41 is the same as the length (L _CX , L _CY ) of one side of the convex portion 41 as shown in FIG. It has become. Further, the distance in the Y direction between the convex portion 41 and the convex portion 41 adjacent to the convex portion 41 is also the same as the length (L _CX , L _CY ) of one side of the convex portion 41 as shown in FIG. It has become. That is, the interval between the convex portions 41 in the X direction and the Y direction is the same as the interval between the convex portions 31 in the X direction and the Y direction (L _AY ).

  As will be described in detail later, these convex portions 41 are arranged in the X direction of the convex portions 41 so as to overlap the convex portions 31 when the separator 14 and the separator 15 are laminated on both sides of the MEA 10. Or the edge in the direction opposite to the X direction is arranged at the same position as the edge in the X direction or the edge in the direction opposite to the X direction of the protrusion 31 (so that the corresponding edges are aligned). Has been.

  Further, an oxidant gas supply port 42 to which an oxidant gas is supplied is formed at the end of the separator 15 in the X direction, and an oxidant from which the oxidant gas is discharged at the end opposite to the X direction. A gas discharge port 43 is formed. A fuel gas supply port 32 through which fuel gas is supplied is formed at the end of the separator 15 in the Y direction, and a fuel gas discharge port 33 through which fuel gas is discharged is formed at the end opposite to the Y direction. Has been.

  In the single cell 9 in which the separator 14 having this configuration is laminated on the anode electrode 12 side surface of the MEA 10 and the separator 15 is laminated on the cathode electrode 13 side surface of the MEA 10, as shown in FIG. The two protrusions 41 formed on the separator 15 correspond to one of the protrusions 31 formed on 14 including an interval between them. Therefore, when the separators 14 and 15 are stacked, even if they slightly deviate from each other, the convex portion 31 and the convex portion 41 can maintain the overlapping state, so that the MEA 10 is applied in the cell stacking direction. The surface pressure can be made uniform. Therefore, excellent power generation efficiency can be maintained. The oxidant gas passage 45 formed in the separator 15 has a total volume (total volume) larger than that of the fuel gas passage 35 formed in the separator 14.

In the fuel cell 1 having this configuration, the fuel gas (hydrogen) supplied from the fuel gas supply port 32 flows through the fuel gas passage 35 and the oxidant gas (air) supplied from the oxidant gas supply port 42. Flows through the oxidant gas passage 45. Here, the shape of the fuel gas channel 35 is defined by the plurality of convex portions 31, and the shape of the oxidant gas channel 45 is defined by the plurality of convex portions 41. The oxidant gas flows almost uniformly through the entire fuel gas channel 35 and the oxidant gas channel 45. Therefore, in each single cell 9, the following electrochemical reaction occurs over the entire power generation region. That is,
On the anode electrode 12 side, H ₂ → 2H ⁺ + 2e ⁻
On the cathode electrode 13 side, (1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O
As a whole fuel cell, H ₂ + (1/2) O ₂ → H ₂ O
At this time, the generated water generated by the electrochemical reaction flows through the oxidant gas flow channel 45. As described above, the oxidant gas flow channel 45 is more comprehensive than the fuel gas flow channel 35. Since the volume is increased, the generated water can be efficiently discharged together with the exhaust gas from the oxidant gas discharge port 43.

In the present embodiment, as viewed from the cell stacking direction, the length (L _AX ) of the convex portion 31 in the X direction is three times the length (L _CX ) of the convex portion 41 in the X direction. Although it explained, the length (L _AX ) of the convex portion 31 in the X direction is an odd number such as about three times or about five times the length (L _CX ) of the convex portion 41 in the X direction. You may set so that it may become a length substantially equal to twice. Moreover, although the length (L _AY ) of the convex portion 31 in the Y direction is the same as the length (L _CY ) of the convex portion 41 in the Y direction in the present embodiment, the present invention is not limited to this. For example, the length (L _AY ) of the convex portion 31 in the Y direction may be substantially the same as the length (L _CY ) of the convex portion 41 in the Y direction. Therefore, for example, a configuration as shown in FIG.

In the embodiment shown in FIG. 7, the length (L _CX , L _CY ) of one side of the convex portion 41 is slightly shorter than that of the above-described embodiment, and the convex portion 41 is between the edge of the convex portion 31. Is positioned inside with a margin (W). In this way, when the separators 14 and 15 are stacked, even if they are slightly displaced laterally, there is a margin (W) between the convex portion 31 and the convex portion 41, so that they overlap each other. It is possible to more reliably maintain the state.

Further, in the present embodiment, the convex portion 31 has a rectangular shape and the convex portion 41 has a square shape when viewed from the cell stacking direction. The maximum length (L _AX ) may be a shape longer than the maximum length (L _AY ) in the Y direction, and may be, for example, an ellipse, an ellipse, or a polygon. Moreover, the convex part 41 may be another shape such as a circle, a polygon, a rectangle, an ellipse, or an ellipse. In the case of the above-described embodiment, the convex portion 31 is rectangular when viewed from the cell stacking direction, and thus the maximum length in the X direction (L _AX ) is the long side.

  In addition, the interval between the convex portion 31 and the convex portion 31, and the interval between the convex portion 41 and the convex portion 41 are within a range in which the convex portion 31 and the convex portion 41 can overlap in the cell stacking direction, and the X direction and the Y direction. Both directions can be set arbitrarily.

  Furthermore, in the present embodiment, a case has been described in which the convex portions 31 are arranged in a state of being spaced apart from each other in the X direction and the Y direction. As shown in FIG. 2, the arrangement pattern may be appropriately arranged in a staggered pattern or the like. In this case, the arrangement position of the convex portion 41 may be appropriately determined so as to overlap the convex portion 31 in the cell stacking direction.

  In the present invention, the polymer electrolyte fuel cell has been described. However, the present invention is not limited to this, and the present invention is naturally applicable to other types of fuel cells.

It is a top view of the separator arrange | positioned at the anode electrode side of the fuel cell concerning embodiment of this invention. It is a top view of the separator arrange | positioned at the cathode electrode side of the fuel cell concerning embodiment of this invention. It is a top view which expands and shows a part of separator shown in FIG. It is a top view which expands and shows a part of separator shown in FIG. It is the whole schematic figure in the posture which made the cell lamination direction of the fuel cell concerning an embodiment of the invention the up-and-down direction. It is sectional drawing which expands and shows a part of single cell which is a component of the fuel cell stack concerning this Embodiment. It is a top view which shows typically the state with which the convex part of the separator arrange | positioned at the anode electrode side concerning the other Example of this invention overlapped with the convex part of the separator arrange | positioned at the cathode electrode side. It is an enlarged plan view which shows arrangement | positioning of the convex part of the separator arrange | positioned at the anode electrode side concerning the other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 9 ... Single cell, 10 ... MEA, 11 ... Electrolyte membrane, 12 ... Anode electrode, 13 ... Cathode electrode, 14, 15 ... Separator, 23 ... Stack, 31, 41 ... Projection, 35 ... Fuel gas Channel, 45 ... Oxidant gas channel

Claims (6)

An anode electrode is disposed on one surface of the electrolyte, and a cathode electrode is disposed on the other surface, each disposed on a surface opposite to the surface on which the electrolyte of the anode electrode and the cathode electrode is disposed. A separator having a fluid flow path defined by a plurality of convex portions formed on a surface facing the electrode, and a fuel cell comprising:
The plurality of convex portions are arranged apart from each other in the X direction and the Y direction, which are at least two directions parallel to the surface of the separator,
As viewed from the stacking direction, the convex portion formed on the surface facing the anode electrode has a maximum length in the X direction (L _AX ) longer than a maximum length in the Y direction (L _AY ). The maximum length (L _AX ) is substantially the same as an odd multiple of the maximum length in the X direction (L _CX ) of the convex portion formed on the surface facing the cathode electrode, and the maximum length in the Y direction (L _AY ) is substantially the same as the maximum length (L _CY ) in the Y direction of the convex portion formed on the surface facing the cathode electrode,
The distance in the X direction between the protrusions formed on the surface facing the cathode electrode when viewed from the stacking direction is substantially the same as the maximum length (L _CX ) of the protrusions in the X direction.
A fuel cell in which a protrusion formed on a surface facing the anode electrode and a protrusion formed on a surface facing the cathode electrode are overlapped in the stacking direction.   When viewed from the stacking direction, the spacing in the X direction between the convex portions formed on the surface facing the cathode electrode is substantially the same as the spacing in the X direction between the convex portions formed on the surface facing the anode electrode. The fuel cell according to claim 1, wherein   When viewed from the stacking direction, the spacing in the Y direction between the convex portions formed on the surface facing the cathode electrode is substantially the same as the spacing in the Y direction between the convex portions formed on the surface facing the anode electrode. The fuel cell according to claim 1 or 2, wherein   The fuel cell according to any one of claims 1 to 3, wherein a convex portion formed on a surface facing the anode electrode when viewed from the stacking direction is substantially rectangular.   The fuel cell according to any one of claims 1 to 4, wherein a convex portion formed on a surface facing the cathode electrode as viewed from the stacking direction is substantially square. The fuel cell according to any one of claims 1 to 5, wherein the electrolyte is an electrolyte membrane, and a membrane-electrode assembly is configured by the electrolyte membrane, the anode electrode, and the cathode electrode.

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