JP5125217B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell, and more particularly to a fuel cell seal structure.

  The fuel cell is used as a fuel cell stack in which a plurality of fuel cells (hereinafter referred to as “unit cells”) are stacked. The unit cell itself is also a laminate of planar members, and has a membrane electrode assembly (MEA) in which an electrolyte membrane is sandwiched between electrodes from both sides, and the MEA flows from both sides of the gas. It is comprised by pinching with a path and a separator.

  In such a fuel cell stack, various seal structures are employed in order to prevent leakage of reaction gas from the laminated surface. For example, Japanese Patent Application Laid-Open No. 2006-260910 discloses a fuel cell in which a sealing member is disposed by combining two or more rubber materials. According to this fuel cell, a seal member made of a rubber material having excellent sealing properties is disposed in a portion where the pressure is weak or where the temperature distribution is high, and in a portion where the pressure is strong or where the temperature distribution is low Another type of sealing member that is not a rubber material having excellent sealing properties is disposed. Thereby, the sealing property can be improved without increasing the manufacturing cost.

JP 2006-260910 A JP 2006-172845 A JP-A-2005-93169 JP 2004-31254 A JP 2004-193108 A

  By the way, in the fuel cell having a structure in which the gas flow path is sandwiched between the MEA and the separator, the seal member disposed so as to surround the outer edge of the gas flow path is compressed and deformed in the stacking direction of the stack, The gas flow path is sealed. As the gas channel, for example, a channel made of a porous metal is used, but in order to optimize the gas supply, the thickness of the gas channel arranged on the anode side and the cathode side are arranged. In some cases, the thickness of the gas flow path is different. In such a case, the seal member needs to be set to a height corresponding to each channel thickness so that a predetermined crushing allowance (compression deformation amount) is ensured.

  However, if the height of the seal member is simply different between the front and back of the MEA, the deformation amount of the seal member having a high height is larger than the deformation amount of the seal member having a low height. As a result, shear stress is generated in the MEA, which may reduce the durability of the fuel cell.

  The present invention has been made to solve the above-described problems, and suppresses leakage of reaction gas without reducing durability in a fuel cell in which the thickness of the gas flow path at both poles of the MEA is different. An object of the present invention is to provide a fuel cell that can handle the above.

In order to achieve the above object, a first invention is a fuel cell,
A membrane electrode assembly configured by sandwiching an electrolyte membrane between electrodes;
A first gas flow path disposed on one electrode of the membrane electrode assembly;
A second gas channel disposed on the other electrode of the membrane electrode assembly and formed thinner than the first gas channel;
A separator that sandwiches the first gas channel and / or the second gas channel with the membrane electrode assembly;
In a fuel cell configured by laminating a plurality of sealing members sandwiched between the membrane electrode assembly and the separator and maintaining the airtightness of the fuel cell by contracting in the stacking direction,
The sealing member is
A first seal member disposed on the first gas flow path side in the membrane electrode assembly;
A second seal member that is disposed on the second gas flow path side in the membrane electrode assembly and is formed to have a lower height in the stacking direction than the first seal member;
When the fuel cell is fastened with a predetermined fastening force, the shrinkage amount in the stacking direction of the first seal member and the second seal member is substantially equal.

The second invention is the first invention, wherein
The sealing member is made of an elastic material having higher hardness as the height in the stacking direction is higher.

The third invention is the second invention, wherein
In the sealing member, the ratio between the hardness of the first seal member and the hardness of the second seal member is a ratio between the height in the stacking direction of the first seal member and the height in the stacking direction of the second seal member. The fuel cell according to claim 2, wherein the fuel cells are configured to be substantially equal.

Moreover, 4th invention is set in 1st invention,
The sealing member is configured such that the higher the height in the stacking direction, the larger the contact area with the membrane electrode assembly.

The fifth invention is the fourth invention, wherein
In the sealing member, a ratio of a contact area in the first seal member and a contact area in the second seal member is such that a height in the stacking direction in the first seal member and a height in the stacking direction in the second seal member. It is characterized by being configured to be substantially equal to the ratio.

Further, the sixth invention is the invention according to any one of the first to fifth inventions,
The first seal member and the second seal member are formed integrally with the membrane electrode assembly.

  In a fuel cell in which a gas flow path disposed on one electrode in a membrane electrode assembly (MEA) and a gas flow path disposed on the other electrode have different thicknesses, the MEA and the separator The sealing members sandwiched between them are configured to have different heights in the stacking direction according to the thickness of the corresponding gas flow path. According to the first invention, the seal members having different heights are configured so that the amount of compressive deformation in the stacking direction becomes substantially equal when the fuel cell is fastened with a predetermined fastening force. For this reason, according to the present invention, it is possible to effectively avoid a situation in which shear stress is generated in the MEA, and to effectively suppress a situation in which the durability of the fuel cell is lowered.

  According to the second invention, the sealing member is made of an elastic material having higher hardness as the height of the sealing member in the stacking direction is higher. When the compressive force applied to the seal member is equal, the amount of compressive deformation increases as the height of the seal member in the stacking direction increases. On the other hand, the higher the hardness of the material, the smaller the amount of compressive deformation. For this reason, according to the present invention, even if the heights of the seal members in the stacking direction are different, the amount of compressive deformation of these seal members can be made equal by adjusting the hardness of the materials used. it can.

  According to the third invention, the ratio between the hardness of the first seal member and the hardness of the second seal member is approximately equal to the ratio between the height in the stacking direction of the first seal member and the height in the stacking direction of the second seal member. The hardness of the seal member is set so as to be equal. In the elastic region of the seal member, the length in the strain direction has a correlation with the deformation amount, and the hardness of the material also has a correlation with the deformation amount. For this reason, according to this invention, the amount of compressive deformation of these sealing members can be made equal by setting the hardness of the material used according to the height ratio of the lamination direction of a sealing member.

  According to 4th invention, the sealing member is comprised so that the contact area to MEA may become large, so that the height of the lamination direction of this sealing member is high. When the compressive force applied to the seal member is equal, the amount of compressive deformation increases as the height of the seal member in the stacking direction increases. On the other hand, the larger the area on which the compressive force acts, the smaller the amount of compressive deformation. For this reason, according to this invention, even if it is a case where the height of the lamination direction of a sealing member differs, the amount of compressive deformation of these sealing members can be made equal by adjusting the contact area to MEA. .

  According to the fifth invention, the ratio of the contact area of the first seal member to the MEA and the contact area of the second seal member to the MEA is such that the height in the stacking direction of the first seal member and the stack of the second seal member The shape of the seal member is set so as to be substantially equal to the ratio to the height in the direction. In the elastic region of the seal member, the length in the strain direction correlates with the deformation amount, and the action area with respect to the strain direction also correlates with the deformation amount. Therefore, according to the present invention, by setting the contact area of the seal member used to the MEA in accordance with the height ratio of the seal member in the stacking direction, the amount of compressive deformation of these seal members is made equal. be able to.

  According to the sixth aspect of the invention, the present invention can be implemented using a seal-integrated MEA in which the MEA, the first seal member, and the second seal member are integrally formed.

  Several embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted. The present invention is not limited to the following embodiments.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
The fuel cell as an embodiment of the present invention is used in a power generation system (fuel cell system) as shown in FIG. FIG. 7 is a schematic configuration diagram showing an entire fuel cell system in which the fuel cell according to the present invention can be used. This fuel cell system is suitable as a vehicle fuel cell system mounted on a fuel cell vehicle. Of course, application to fuel cell systems for other purposes is also possible.

  In the fuel cell system shown in FIG. 7, hydrogen (hereinafter also referred to as “anode gas”) as a fuel gas is supplied to the fuel cell 100. Hydrogen supplied to the fuel cell 100 is stored in a high-pressure hydrogen tank 114. The hydrogen tank 114 and the anode of the fuel cell 100 are connected by a hydrogen supply pipe 110, and a shut valve 116 and a pressure regulating valve 118 are disposed in the middle of the hydrogen supply pipe 110. Further, an off-gas discharge pipe 112 for discharging anode off-gas is connected to the anode of the fuel cell 100. The off-gas discharge pipe 112 is connected to the downstream side of the pressure regulating valve 118 in the hydrogen supply pipe 110 and constitutes a hydrogen circulation system together with the hydrogen supply pipe 110. A circulation pump 120 for circulating hydrogen in the circulation system is disposed in the middle of the offgas discharge pipe 112.

  In this system, air as an oxidizing gas (hereinafter also referred to as “cathode gas”) is supplied to the fuel cell 100. Air supplied to the fuel cell 100 is taken in from the atmosphere by the compressor 134. The compressor 134 and the cathode of the fuel cell 100 are connected by an air supply pipe 130. Further, an off-gas discharge pipe 132 for discharging the cathode off-gas is connected to the cathode of the fuel cell 100. The off gas discharge pipe 132 is opened to the atmosphere, and a pressure regulating valve 136 for adjusting the air pressure is provided in the middle of the pipe line.

  Further, in this system, a coolant (water, antifreeze, air, or the like) for cooling the fuel cell 100 is supplied to the fuel cell 100 separately from the reaction gas (fuel gas and oxidizing gas). The fuel cell 100 is connected to a refrigerant supply pipe 140 for supplying a refrigerant and a refrigerant discharge pipe 142 for discharging the refrigerant. Both the refrigerant supply pipe 140 and the refrigerant discharge pipe 142 are connected to the radiator 146, and the refrigerant circulates from the refrigerant discharge pipe 142 to the refrigerant supply pipe 140 through the radiator 146. A circulation pump 148 for circulating the refrigerant in the circulation system is arranged in the middle of the refrigerant discharge pipe 142.

  The fuel cell 100 of the present embodiment has a stack structure in which a plurality of unit cells 10 are stacked. FIG. 1 is an exploded perspective view of the unit cell 10. As shown in this figure, the unit cell 10 includes a power generation body 12, a porous body flow path 14 through which oxidizing gas flows, a porous body flow path 16 through which fuel gas flows, and a separator 18 that isolates adjacent power generation bodies 12 from each other. Yes. The power generation body 12 is integrally formed outside a membrane electrode assembly (MEA) 20 in which an anode and a cathode are arranged with an electrolyte membrane interposed therebetween, and a gas diffusion layer (not shown) is surrounded by a seal gasket.

  The porous body channels 14 and 16 are formed of a foamed sintered metal such as stainless steel, titanium, or a titanium alloy, or a porous body having a large number of pores inside a metal mesh or the like. Since the porous body channels 14 and 16 are mainly intended to flow the reaction gas in a predetermined direction, a porous body having a relatively high porosity is formed so as to suppress the pressure loss of the flow of the reaction gas and to structure drainage. used. The reaction gas introduced into the porous body channels 14 and 16 passes through the internal pores and is supplied to the anode and cathode of the MEA 20.

  The separator 18 is a three-layer laminated separator formed by laminating thin conductive metal plates such as stainless steel and titanium. More specifically, the cathode plate is in contact with the porous body flow path 14, the anode plate is in contact with the porous body flow path 16, and an intermediate plate sandwiched between these plates. The intermediate plate is formed with a plurality of grooves (not shown) as refrigerant flow paths.

  Next, the configuration of the power generator 12 will be described in detail with reference to FIG. FIG. 2 is a diagram for explaining the configuration of the power generator 12. FIG. 2A shows the power generation body 12 as seen from the stacking direction of the stack. Moreover, FIG.2 (b) is sectional drawing which shows typically the II-II cross section in Fig.2 (a). As shown in this figure, the MEA 20 includes a cathode 24 and an anode 26 as electrode catalyst layers, respectively, on the surface of the electrolyte membrane 22. The electrolyte membrane 22 is a thin film of a solid polymer material that has proton conductivity and exhibits good electrical conductivity in a wet state. The cathode 24 and the anode 26 formed on the surface of the electrolyte membrane 22 include a catalyst (for example, platinum) that promotes an electrochemical reaction.

  Further, as shown in FIG. 2B, gas diffusion layers 28 are respectively disposed outside the cathode 24 and the anode 26 in the MEA 20. The gas diffusion layer 28 is composed of a carbon porous body (for example, carbon cloth) having a porosity of about 60 to 70%. Hereinafter, the MEA 20 in which the gas diffusion layer 28 is integrated will be referred to as MEGA 30.

  Further, the power generator 12 of the present embodiment is formed by surrounding the MEGA 30 with a seal gasket 32. The seal gasket 32 is an insulating resin material having elasticity, such as silicon rubber, butyl rubber, or fluorine rubber, and is formed around the MEGA 30 so as to sandwich a part of the outer periphery of the MEGA 30 in the thickness direction. Has been.

  The outer shape of the seal gasket 32 is formed in a substantially rectangular shape identical to that of the separator 18, and through holes are formed along the four sides thereof to form a manifold for reaction gas and refrigerant. Around these manifolds and around the MEGA 30, a lip 34a formed in a convex shape in the thickness direction of the cathode 24 side of the seal gasket 32 is provided. Similarly, a lip 34b formed in a convex shape is formed on the anode 26 side of the seal gasket 32 (hereinafter, when these are not particularly distinguished, they are simply referred to as “lip 34”). The lip 34 is contacted with the separator 18 sandwiching the seal gasket 32 to be deformed by receiving a predetermined fastening force (compression force) in the stacking direction of the stack, and suppresses leakage of reaction gas flowing on the surface of the manifold or MEGA 30. Form a line.

[Characteristic configuration of the present embodiment]
Next, a characteristic configuration of the present embodiment will be described with reference to FIGS. FIG. 3 is a diagram showing a part of a cross section of fuel cell 100 of the present embodiment cut in the stacking direction. As shown in this figure, in the present embodiment, the porous channel 14 arranged on the cathode 24 side of the MEGA 30 and the porous channel 16 arranged on the anode 26 side of the MEGA 30 Each of the thicknesses is optimum for supplying. For this reason, these porous body flow paths 14 and 16 are comprised as mutually different thickness.

  In such a unit cell 10, the height of the lip 34 is set according to the thickness of the porous body channels 14 and 16. More specifically, the height of the lip 34a corresponding to the porous body channel 14 is set high, and the height of the lip 34b corresponding to the porous body channel 16 thinner than the porous body channel 14 is set low. .

  However, if the same fastening force is applied to the lips 34a and 34b, a difference in the amount of compressive deformation occurs between the lips 34a and 34b. FIG. 4 is a schematic diagram for explaining a state in which a predetermined fastening force is applied to the unit cell 10. As shown in this figure, the lip 34a having a high lip height is greatly deformed as compared with the lip 34a. That is, a deviation occurs in the relative positional relationship between the lip 34 and the MEGA 30 in the power generation body 12. For this reason, damage or the like occurs in the power generation body 12 due to the shear stress generated in the power generation body 12, and the durability of the fuel cell may be reduced.

  Therefore, in the fuel cell according to the present embodiment, the lip 34a and 34b in the unit cell 10 are made of materials having different hardnesses so that the amount of compressive deformation of these lips 34 is made equal. FIG. 5 is a diagram schematically showing a cross section of the unit cell 10 in which the lips 34a and 34b are made of different materials. As shown in this figure, the lip 34a side and the lip 34b side of the seal gasket 32 are made of materials having different compositions. More specifically, when a predetermined fastening force is applied to the unit cell 10, the composition of each material is determined so that the amount of compressive deformation of the lip 34a and the lip 34b is the same. Hereinafter, an example of the calculation for determining the material composition will be described. In the following calculation, it is assumed that the lips 34a and 34b have a lip shape having a rectangular cross-sectional shape in the stacking direction.

First, assuming that the stress σ _a , the strain ε _a , the elastic modulus E _a , the height h _a , and the amount of compressive deformation Δh _a in the lip 34a, σ _a and ε _a are approximately expressed by the following equations.
σ _a = ε _a E _a (1)
ε _a = Δh _a / h _a (2)

Contact area _{A a} of the lip 34a and the separator 18, the above equation as a stack fastening force P (1), by modifying (2), the amount of compressive deformation Delta] h _a is expressed by the following equation.
Δh _a = h _a σ _a / E _a = Ph _a / A _a E _a (3)

Similarly, assuming that the stress σ _b , strain ε _b , elastic modulus E _b , height h _b , compression deformation amount Δh _b , contact area A _b , and fastening force P in the lip 34 _b , the compression deformation amount Δh _b is expressed by the following equation: It is represented by
Δh _b = h _b σ _b / E _b = Ph _b / A _b E _b (4)

In the unit cell 10 in the present embodiment, since the contact area _{A a} and _{A b} of the lip 34 is equal, the lip 34a, the amount of compressive deformation Delta] h _a of 34b, the elastic modulus for Delta] h _b is equal _{E a} and _{E b} This relationship is derived as follows by arranging the above equations (3) and (4).
E _b / E _a = h _b / h _a (5)

  Thus, by composing the material so that the elastic coefficient satisfies the relationship shown in the above equation (5), the amount of compressive deformation in the lip 34a and the lip 34b when a predetermined fastening force acts on the stack is made equal. be able to. Thereby, the situation where a shear stress is generated in the power generation body 12 can be effectively avoided.

  By the way, in Embodiment 1 mentioned above, the lip | rip 34 is formed integrally with the electric power generation body 12, However, The structure of the lip | rip 34 is not restricted to this. That is, the present invention may be implemented in a fuel cell in which a seal gasket corresponding to the lip 34 is provided separately from the power generator 12.

  In the first embodiment described above, a fuel cell is used in which the porous channel 14 is thicker in the stacking direction than the porous channel 16, but the configuration of the fuel cell is the same. Not limited. That is, in order to optimize the supply of the reaction gas, the present invention is implemented in a fuel cell in which the porous channel 16 through which the fuel gas flows is configured to be thicker than the porous channel 14. Also good.

In the first embodiment described above, the shape of the lip 34 in the seal gasket 32 is a column shape, but the lip shape is not limited to this. That is, if the composition of the material can be set so that the compression deformation amounts Δh _a and Δh _b are equal when a predetermined fastening force is applied, the cross-sectional shape in the stacking direction is trapezoidal or semicircular. May be.

  In the first embodiment described above, the porous body flow path 14 is the “first gas flow path” in the first invention, and the porous body flow path 16 is the “second gas flow path” in the first invention. The seal gasket 32 is the “seal member” in the first invention, the lip 34a is the “first seal member” in the first invention, and the lip 34b is the “second seal member” in the first invention. Respectively.

Embodiment 2. FIG.
[Configuration of Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram schematically showing a cross section of the unit cell 40 in the fuel cell of the second embodiment. In the unit cell 40 shown in FIG. 6, elements common to the unit cell 10 shown in FIG.

  As shown in this figure, the unit cell 40 is formed by surrounding the MEGA 30 with a seal gasket 42. Further, a lip 44a formed as a convex shape on the cathode 24 side and a lip 44b formed as a convex shape on the anode 26 side are provided around the manifold and the MEGA 30 in the seal gasket 42 (hereinafter referred to as these). Are simply referred to as “lip 44”). The lip 44 is contacted with the separator 18 sandwiching the seal gasket 42 to be deformed by receiving a predetermined fastening force (compression force) in the stacking direction of the stack, and suppresses leakage of reaction gas flowing on the surface of the manifold or MEGA 30. Form a line.

[Features of Embodiment 2]
In the above-described first embodiment, when the fuel cell is fastened as a stack, materials having different hardness are used for each lip so that the amount of compressive deformation of the lips 34a and 34b in the seal gasket 32 becomes equal. I am going to do that. That is, the seal gasket 32 is made of two kinds of materials, and the amount of compression change of the lip 34 is adjusted by changing the material used, that is, the elastic coefficient specific to the material.

On the other hand, even if the material used for the lip is not changed, the amount of change in compression can be adjusted by the lip shape of the seal gasket. That is, the larger the contact area between the lip and the separator, the smaller the amount of compressive deformation in the lip. Therefore, in the second embodiment, a contact area _{A b} of the separator 18 at the lip 44a, by adjusting the contact area _{A a} in the lip 44a, equalizing the compressive deformation amount in these lips 44a, 44b And The setting of the contact areas A _a and A _b can be performed, for example, by the following calculation. In the following calculation, it is assumed that the lips 44a and 44b are lip shapes having a rectangular cross-sectional shape in the stacking direction.

In the unit cell 40 in this embodiment, since the elastic modulus E _b of the elastic modulus E _a lip 44b of the lip 44a are equal, the above equation (3), the following relationship is guided to organize (4).
A _b / A _a = h _b / h _a (6)

As described above, the lip 44 is formed so that the contact area A satisfies the relationship expressed by the above equation (6), and thus, the amount of compressive deformation in the lip 44a and the lip 44b when a predetermined fastening force is applied to the stack. Δh _a and Δh _b can be made equal. As a result, it is possible to effectively suppress a situation in which shear stress is generated inside the power generator 12 and the durability of the fuel cell is lowered.

  By the way, in Embodiment 2 mentioned above, the lip 44 is integrally formed with the electric power generation body 12, However, The structure of the lip 44 is not restricted to this. That is, the present invention may be implemented in a fuel cell in which a seal gasket corresponding to the lip 44 is provided separately from the power generator 12.

  In the second embodiment described above, a fuel cell is used in which the porous channel 14 is thicker in the stacking direction than the porous channel 16, but the configuration of the fuel cell is the same. Not limited. That is, in order to optimize the supply of the reaction gas, the present invention is implemented in a fuel cell in which the porous channel 16 through which the fuel gas flows is configured to be thicker than the porous channel 14. Also good.

In the second embodiment described above, the shape of the lip 44 in the seal gasket 42 is a column shape, but the lip shape is not limited to this. That is, if the shape of the lip 44 can be set so that the compression deformation amounts Δh _a and Δh _b are equal when a predetermined fastening force is applied, the cross-sectional shape in the stacking direction is a trapezoidal shape or a semicircular shape. There may be.

  In the second embodiment described above, the porous body channel 14 is the “first gas channel” in the first invention, and the porous body channel 16 is the “second gas channel” in the first invention. The seal gasket 42 is the “seal member” in the first invention, the lip 44a is the “first seal member” in the first invention, and the lip 44b is the “second seal member” in the first invention. Respectively.

2 is an exploded perspective view of a unit cell 10. FIG. FIG. 3 is a diagram for explaining a configuration of a power generator 12. It is a figure which shows a part of cross section which cut | disconnected the fuel cell 100 of this Embodiment 1 in the lamination direction. 4 is a schematic diagram for explaining a state in which a predetermined fastening force is applied to the unit cell 10. FIG. It is a figure for demonstrating the structure of the seal gasket 32 in the unit cell 10 of this Embodiment 1. FIG. It is a figure for demonstrating the structure of the seal gasket 42 in the unit cell 40 of this Embodiment 2. FIG. It is a schematic structure figure showing the whole fuel cell system.

Explanation of symbols

10 unit cell 12 power generation body 14 porous body flow path (cathode side)
16 Porous channel (anode side)
18 Separator 20 MEA (Membrane Electrode Assembly)
22 Electrolyte membrane 24 Cathode 26 Anode 28 Gas diffusion layer 30 MEGA
32 Seal gasket 34 Lip 40 Unit cell 42 Seal gasket 44 Lip 100 Fuel cell 110 Hydrogen supply pipe 112 Off gas discharge pipe 114 Hydrogen tank 116 Shut valve 118 Pressure regulating valve 120 Circulation pump 130 Air supply pipe 132 Off gas discharge pipe 134 Compressor 136 Pressure regulation Valve 140 Refrigerant supply pipe 142 Refrigerant discharge pipe 146 Radiator 148 Circulation pump

Claims (6)

A membrane electrode assembly configured by sandwiching an electrolyte membrane between electrodes;
A first gas flow path disposed on one electrode of the membrane electrode assembly;
A second gas channel disposed on the other electrode of the membrane electrode assembly and formed thinner than the first gas channel;
A separator sandwiching the first gas channel and / or the second gas channel with the membrane electrode assembly;
In a fuel cell configured by laminating a plurality of sealing members sandwiched between the membrane electrode assembly and the separator and maintaining the airtightness of the fuel cell by contracting in the stacking direction,
The sealing member is
A first seal member disposed on the first gas flow path side in the membrane electrode assembly;
A second seal member that is disposed on the second gas flow path side in the membrane electrode assembly and is formed to have a lower height in the stacking direction than the first seal member;
When the fuel cell is fastened with a predetermined fastening force, the amount of contraction in the stacking direction of the first seal member and the second seal member is substantially equal.   The fuel cell according to claim 1, wherein the seal member is made of an elastic material having a higher hardness as the height in the stacking direction is higher.   In the sealing member, the ratio between the hardness of the first seal member and the hardness of the second seal member is a ratio between the height in the stacking direction of the first seal member and the height in the stacking direction of the second seal member. The fuel cell according to claim 2, wherein the fuel cells are configured to be substantially equal.   2. The fuel cell according to claim 1, wherein the seal member is configured such that the contact area with the membrane electrode assembly increases as the height in the stacking direction increases.   In the sealing member, a ratio of a contact area in the first seal member and a contact area in the second seal member is such that a height in the stacking direction in the first seal member and a height in the stacking direction in the second seal member. The fuel cell according to claim 4, wherein the fuel cell is configured to be substantially equal to the ratio.   The fuel cell according to any one of claims 1 to 5, wherein the first seal member and the second seal member are formed integrally with the membrane electrode assembly.

Images