Fuel Cells

Abstract

To suppress the occurrence of damage to a membrane electrode assembly and a gas diffusion layer in bonding of a support and the membrane electrode assembly.SOLUTION: A fuel cell includes a membrane electrode assembly including a first catalyst layer, a second catalyst layer, and an electrolyte membrane disposed between the first catalyst layer and the second catalyst layer, a first gas diffusion layer that is laminated on the first catalyst layer and has at least a portion of its outer peripheral edge extending beyond the outer peripheral edge of the membrane electrode assembly, a second gas diffusion layer stacked on the second catalyst layer, a support disposed at least partially around the membrane electrode assembly, and a cover sheet disposed between the first gas diffusion layer and the membrane electrode assembly so as to span the support and at least one end of the electrolyte membrane and the first catalyst layer. The cover sheet includes a sheet portion that is a layer on the membrane electrode assembly side, and a permeation portion that is laminated on the sheet portion and permeates the first gas diffusion layer.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to fuel cells. [Background technology]

[0002] Patent Documents 1, 2, and 3 disclose frame members (resin frame members, support frames) Patent Document 4 discloses that the support frame and the electrode laminate are bonded with an adhesive. An adhesive and a cover sheet are arranged so as to bridge the glass and the membrane electrode assembly, and the glass is attached to the cover sheet. A structure in which a gas diffusion layer is laminated is disclosed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-057200 [Patent Document 2] Patent Publication No. 2021-057209 [Patent Document 3] JP 2020-145026 A [Patent Document 4] JP 2021-144854 A Summary of the Invention [Problem to be solved by the invention]

[0004] As in Patent Documents 1 to 3, when the frame member and the electrode laminate are directly joined with an adhesive, the frame There is a risk that the electrode laminate may be damaged due to thermal expansion and contraction of the materials and other components, or due to external forces. In addition, when a cover sheet is provided as in Patent Document 4, the membrane electrode assembly and the gas The phenomenon of damage occurring in the diffusion layer was confirmed, and this damage may lead to leakage of reactive gas. be.

[0005] In view of the above problems, the present disclosure provides a method for bonding a support and a membrane electrode assembly. The present invention aims to provide a fuel cell capable of suppressing damage to the fuel cell body and gas diffusion layer. . [Means for solving the problem]

[0006] The inventors have conducted extensive research and have discovered that the cover sheet has a sheet portion and an adhesive layer that fixes the sheet portion. The thickness of the cover sheet is the cause of the increase in the thickness of the cover sheet at the tip of the cover sheet on the membrane electrode assembly side. It was found that this space was the cause of damage to the membrane electrode assembly and gas diffusion layer. The inventors then developed a specific solution to this problem, and completed the technology disclosed herein. is as follows:

[0007] The present application relates to a first catalyst layer, a second catalyst layer, and a catalyst layer disposed between the first catalyst layer and the second catalyst layer. A membrane electrode assembly having an electrolyte membrane and a first catalyst layer. A first gas diffusion layer is provided beyond the outer peripheral edge of the membrane electrode assembly, and a second catalyst layer is laminated on the first gas diffusion layer. a second gas diffusion layer having a first electrode and a second electrode disposed around at least a portion of the periphery of the membrane electrode assembly; A first gas diffusion layer is disposed between the support and at least one end of the electrolyte membrane and the first catalyst layer. and a cover sheet disposed between the layer and the membrane electrode assembly, the cover sheet being disposed between the membrane electrode The sheet portion, which is the layer on the joining body side, and the gas diffusion layer, which is laminated on the sheet portion and permeates the first gas diffusion layer, and a permeation portion having a first electrode and a second electrode.

[0008] The first gas diffusion layer is a diffusion member and a matrix provided on the surface of the diffusion member facing the first catalyst layer. The permeation portion of the cover sheet extends beyond the microporous layer to form a diffusion member. The configuration may be such that the penetration

[0009] The end face of the support and the end face of the membrane electrode assembly may be disposed opposite to each other with a gap therebetween. Effect of the Invention

[0010] According to the present disclosure, in a fuel cell, a cover sheet is attached to a first gas diffusion layer side by an adhesive layer. The adhesive layer was allowed to penetrate into the first gas diffusion layer, so that the cover sheet on the membrane electrode assembly side This makes it possible to reduce the size of the space at the tip of the membrane electrode assembly and gas diffusion layer. The occurrence of damage can be suppressed. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a plan view of a power generating unit cell 10. As shown in FIG. [Diagram 2] FIG. 2 is a cross-sectional view of the power generating section 11, illustrating its layer structure. [Diagram 3] FIG. 3 is a cross-sectional view of the outer periphery 21, illustrating its layer structure. [Figure 4] FIG. 4 is an enlarged view of a portion of FIG. [Diagram 5] FIG. 5 is a diagram for explaining another embodiment. [Figure 6] FIG. 6 is a diagram for explaining another embodiment. [Figure 7] FIG. 7 is a diagram for explaining a method for arranging a cover sheet. [Figure 8] FIG. 8 is a diagram illustrating the fuel cell 30. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 1.Power generation unit cell 1 to 3 are diagrams illustrating a power generating unit cell 10 according to one embodiment. The module 10 is a unit element that generates electricity by supplying hydrogen and oxygen (air). A fuel cell is formed by stacking a plurality of such power generating unit cells 10. FIG. 1 is a plan view of a power generating unit cell 10, and FIG. 2 is a plan view of a power generating section 11 of the power generating unit cell 10. FIG. 3 is a diagram for explaining the layer structure in the outer peripheral portion 21 of the power generating unit cell 10. FIG.

[0013] 1.1.Power Generation Section The power generating unit 11 is a part that contributes to power generation, for example, in the area surrounded by the dotted line in FIG. As shown in FIG. 2, the layer structure of the power generating section 11 (part of the AA cross section) is a laminate of multiple layers. This is what happens. In the power generating section 11 of the power generating unit cell 10, one side of the electrolyte membrane 12 is a cathode (oxygen supply The cathode is connected to the electrolyte membrane 12 side by a cathode catalyst. A catalyst layer 13 (first catalyst layer), a cathode gas diffusion layer 14 (first gas diffusion layer), and a cathode The anode is made of an electrolyte, a separator 15 (a first separator), and a second separator 16 (a second separator). From the membrane 12 side, an anode catalyst layer 16 (second catalyst layer), an anode gas diffusion layer 17 (second gas diffusion layer), The anode separator 18 (second separator) is provided in this order. The laminate of the electrolyte membrane 12, the cathode catalyst layer 13, and the anode catalyst layer 16 is called a membrane electrode assembly. The thickness of the membrane electrode assembly is typically about 0.4 mm, and the power generation section 11 The thickness of the power generating unit cell 10 in this embodiment is typically about 1.3 mm. Each layer may be constructed as known in the art, for example as follows:

[0014] 1.1a. Electrolyte membrane The electrolyte membrane 12 is a thin solid polymer film that exhibits good proton conductivity in a wet state. For example, it is composed of a fluorine-based ion exchange membrane, and for example, it uses a carbon-fluorine-based polymer. Specifically, perfluoroalkylsulfonic acid polymer (Nafion ( Registered trademark) and others. The thickness of the electrolyte membrane 12 is not particularly limited, but is preferably 100 μm or less, more preferably 50 μm or less, and more preferably 10 μm or less.

[0015] 1.1b. Cathode catalyst layer The cathode catalyst layer 13 is a layer containing a catalyst metal in a form in which the catalyst metal is supported on a carrier. For example, the catalytic metal may be Pt, Pd, Rh, or an alloy containing these. The support may be a carbon support, more specifically, glassy carbon, carbon black, or activated carbon. Examples of carbon particles include those made of charcoal, coke, natural graphite, and artificial graphite.

[0016] 1.1c. Anode catalyst layer The anode catalyst layer 16, like the cathode catalyst layer 13, is made of a catalyst metal supported on a carrier. For example, the catalytic metal may be Pt, Pd, Rh, or Examples of the support include alloys containing these. The support includes carbon supports, more specifically glassy carbon supports. Carbon, carbon black, activated carbon, coke, natural graphite, and artificial graphite. Examples include elementary particles.

[0017] 1.1d. Cathode gas diffusion layer In this embodiment, the cathode gas diffusion layer 14 is made up of a diffusion member 14a and a microporous layer (MPL). )14b. The diffusion member 14a is, for example, a layer made of a conductive porous material. Examples include carbon porous bodies (carbon paper, carbon cloth, glassy carbon, etc.) etc.), metal porous bodies (metal mesh, metal foam), etc. The MPL 14b is a thin coating applied to the cathode catalyst layer 13 side of the diffusion member 14a. MPL14b is a membrane that has the ability to regulate moisture by being water repellent or hydrophilic as needed. MPL14b is made of water-repellent resin such as polytetrafluoroethylene (PTFE). Typically, the main component is a conductive material such as carbon black.

[0018] 1.1e. Anode gas diffusion layer The anode gas diffusion layer 17 is, for example, a layer made of a conductive porous material. More specific examples include carbon porous bodies (carbon paper, carbon cloth, glass-like Examples of the porous material include carbon, metal porous bodies (metal mesh, metal foam), etc.

[0019] 1.1f. Cathode separator The cathode separator 15 supplies a reactant gas (air in this embodiment) to the cathode gas diffusion layer 14. The surface of the cathode gas diffusion layer 14 facing the cathode gas diffusion layer 14 has a plurality of grooves 15a. The grooves function as reaction gas channels. The shape of the grooves is designed to properly diffuse the reaction gas into the cathode gas. As long as it can be supplied to the diffusion layer 14, there is no particular limitation. The serpentine type has a corrugated board shape. The plate thickness is 0.1mm to 0. A typical thickness is 2 mm, and the height of the irregularities is typically about 0.5 mm. In the case of the serpentine type, a cathode separator 15 is sandwiched between adjacent grooves 15a. Then, a groove 15b is formed on the opposite side, which functions as a cooling water flow path.

[0020] As can be seen from FIG. 1, the cathode separator 15 is provided with a An air inlet hole is provided at an outer side of the groove 15a and the groove 15b. A in , cooling water inlet hole W in , hydrogen outlet hole H out The grooves 15a and 15b extend The other end of the extension is provided with an air outlet hole A. out , cooling water outlet hole W out , Hydrogen inlet Hole H in Here, the groove 15a is the air inlet hole A in , Air outlet hole A out To The groove 15b is connected to the cooling water inlet hole W in , cooling water outlet hole W out It is connected to.

[0021] The material constituting the cathode separator 15 is used as a separator for the power generation unit cell. The material may be any material capable of being electrically conductive and gas impermeable. Examples of suitable materials include dense carbon, which is made by compressing carbon to make it gas impermeable, and pressed Examples of the material include a molded metal plate.

[0022] 1.1g. Anode separator The anode separator 18 is a member that supplies a reactant gas (hydrogen) to the anode gas diffusion layer 17. The surface facing the anode gas diffusion layer 17 has a plurality of grooves 18a. The grooves function as reaction gas flow paths. The shape of the grooves is designed to properly guide the reaction gas to the anode gas diffusion layer 17. As long as it can be supplied, there is no particular limitation, and the serpentine type as in this embodiment is In this case, the plate thickness is typically 0.1mm to 0.2mm, and the height of the irregularities is 0. About 4mm is typical. In the case of a serpentine type, an anode separator 18 is sandwiched between adjacent grooves 18a. Then, a groove 18b is formed on the opposite side, which functions as a cooling water flow path.

[0023] As can be seen from FIG. 1, the anode separator 18 is provided with a An air inlet hole is provided at an outer end of the groove 18a and the groove 18b. A in , cooling water inlet hole W in , hydrogen outlet hole H out The grooves 18a and 18b extend The other end of the extension is provided with an air outlet hole A. out , cooling water outlet hole W out , Hydrogen inlet Hole H in Here, the groove 18a is a hydrogen inlet hole H in , hydrogen outlet hole H out To The groove 18b is connected to the cooling water inlet hole W in , cooling water outlet hole W out It is connected to.

[0024] The material constituting the anode separator 18 is used as a separator for the power generating unit cell. The material may be any material capable of being electrically conductive and gas impermeable. Examples of suitable materials include dense carbon, which is made by compressing carbon to make it gas impermeable, and pressed Examples of the material include a molded metal plate.

[0025] 1.1h. Power generation by the power generation unit As is well known, the power generation unit cell 10 described above generates power as follows. . Hydrogen inlet hole H in Hydrogen supplied from the anode separator 18 to the groove 18a is Protons (H + ) and electrons (e - ) The protons pass through the electrolyte membrane 12, and the electrons pass through the conductive wires connected to the outside. The remaining hydrogen reaches the cathode catalyst layer 13. out is discharged from The cathode catalyst layer 13 has an air inlet hole A in From the groove 15a of the cathode separator 15, Oxygen (air) is supplied through the cathode gas diffusion layer 14, and in the cathode catalyst layer 13, Water (H2O) is generated by the protons, electrons, and oxygen. The generated water and the remaining air are The air passes through the cathode gas diffusion layer 14 and reaches the groove 15a of the cathode separator 15 to the air outlet hole A out is discharged from In the power generating unit cell 10, electrons flow through the conductive wire that connects the anode catalyst layer 16 to the outside. is used as the current.

[0026] In addition, the cathode separator 15 of one of the adjacent power generating unit cells 10 The anode separator 18 of the other power generating unit cell 10 adjacent to the other power generating unit cell 10 is arranged so as to overlap with the As a result, the grooves 15b of the cathode separator 15 and the grooves 18b of the anode separator 18 The cooling water flow path is formed by the cooling water inlet hole W in Cooling water is provided from The supplied cooling water cools the power generating unit cells 10 and exits the cooling water outlet W out Discharged from will be done.

[0027] 1.2.Outer periphery The outer peripheral portion 21 is the outer periphery of the power generating unit cell 10 outside the power generating portion 11 surrounded by the dotted line in FIG. As shown in FIG. 3, the layer structure (BB cross section) in the outer peripheral portion 21 is formed by laminating a plurality of layers. It becomes.

[0028] 1.2a. Outer structure As can be seen from FIG. 3, in this embodiment, at least a part of the outer periphery 21 has the following configuration. It is possible. The end faces of the electrolyte membrane 12, the anode catalyst layer 16, and the anode gas diffusion layer 17 are located at approximately the same position. The end face of the cathode catalyst layer 13 was recessed below the end face of the electrolyte membrane 12 (rear The end face of the cathode gas diffusion layer 14 is disposed in a recessed position. The position is projected (advanced) from the end face of the membrane 12, as viewed from above in the power generating unit cell 10 (FIG. 1 (the line of sight in the direction indicated by the arrow L in FIG. 3) so that the support 23 overlaps the support 23. The support 23 will be described later.

[0029] The cathode separator 15 and the anode separator 18 have an outer periphery 21 and an electrode portion therebetween. The cathode separator 15 is disposed so as to sandwich the above-mentioned layers in the same manner as the cathode separator 11. The end faces of the anode separator 18 are connected to the membrane electrode assembly, the cathode gas diffusion layer 14, the anode The card cavity extends beyond each end surface of the gas diffusion layer 17, and the card cavity extends beyond each end surface of the gas diffusion layer 17. A support 23 is disposed between the anode separator 15 and the anode separator 18. In part 21, the cathode separator 15 and the anode separator 18 do not require a flow path. The grooves 15a and 18a are not formed (although as can be seen from FIG. 3, grooves are partially formed). (This does not prevent the implementation of the above.)

[0030] The end of the surface of the support 23 facing the cathode side and the end of the surface of the membrane electrode assembly facing the cathode side The cover sheet 22 is arranged so as to cover the paper. The cover sheet 22 will be described later. do.

[0031] 1.2b. Support The support 23 is connected to the cathode separator 15 at the outer periphery 21 of the power generating unit cell 10. and the anode separator 18. The support 23 is made of a base material 23a and both surfaces of the base material 23a (the surface facing the cathode side and the surface facing the anode side). The adhesive layer 23b is disposed on each of the surfaces of the cathode (the surface facing the cathode). The separator 15 and the anode separator 18 are bonded to each other to seal the inside of the power generating section 11. Therefore, the gap between the cathode separator 15 and the anode separator 18 is The layer between them bends in a way that changes the shape of the support, as can be seen in Figure 3. In the area where only the body 23 is arranged, the gap is narrowed in a part thereof, and the cathode separator The support 23 is sandwiched between the anode separator 15 and the anode separator 18 and fixed.

[0032] The base material 23a is made of a thermoplastic resin material having electrical insulation and airtightness and a relatively high melting point. Such materials include crystalline polymers, more specifically engineered polymers. Examples of engineering plastics include: For example, polyethylene naphthalate resin (PEN) and polyethylene terephthalate resin. (PET) can be mentioned. The thickness of the base material 23a is not particularly limited, but is preferably 0.05 mm or more and 0.25 mm or less. It is preferable that there is.

[0033] The adhesive layer 23b may be any known material as long as it has adhesive properties when bonded. For example, functional groups (maleic anhydride, epoxy, etc.) can be added to polyolefins. Examples of the adhesive include modified polyolefins that are introduced into polyolefins to impart adhesive properties.

[0034] As can be seen from FIG. 3, the end faces of the support 23 are connected to the membrane electrode assembly and the annulus. The power generating unit 1 is disposed so as to face the end face of the gate gas diffusion layer 17 with a gap S therebetween. 1. This gap S reduces the linear expansion of the support 23, the membrane electrode assembly, etc. It can absorb dimensional changes caused by tension, and suppress damage caused by expansion and contraction. can.

[0035] 1.2c. Cover sheet As described above, the end of the surface of the support 23 facing the cathode and the cathode side of the membrane electrode assembly are A cover sheet 22 is disposed so as to span the end of the surface facing the printer. 3 and 4 show an enlarged view of the area around the cover sheet 22. The cover sheet 22 has a sheet portion 22a and a permeation portion 22 laminated on the sheet portion 22a. The sheet portion 22a is on the membrane electrode assembly side, and the permeation portion 22b is on the cathode gas diffusion side. It faces the scattering layer 14 side.

[0036] One end of the sheet portion 22a is a surface end portion on the cathode side of the support 23, and the other end is a The cathode catalyst layer 13 is disposed so as to cover at least one of the surface ends of the electrolyte membrane 12 and the cathode catalyst layer 13. In this embodiment, the sheet portion 22a is disposed on both the surface edges of the electrolyte membrane 12 and the cathode catalyst layer 13. As a result, the cathode and the anode are separated from each other at the outer peripheral portion 21. It is possible to appropriately separate the

[0037] The sheet portion 22a is made of a material that is impermeable to the reactant gas of the fuel cell. Examples of materials that are impermeable to ultraviolet rays include polypropylene, polyphenylene sulfide, and poly Made of resins such as ethylene naphthalate, nylon, and ethylene vinyl alcohol copolymer A film-like material can be used. In particular, from the viewpoints of hydrolysis resistance and adhesion to the electrolyte membrane, From these, nylon 11, nylon 12, nylon 9T, and ethylene vinyl alcohol are listed. In order to increase the adhesion to the electrolyte membrane 12, an amide group, an epoxy group, a hydroxyl group, etc. Additives having groups or the like may be added.

[0038] The thickness of the sheet portion 22a is not particularly limited, but is preferably about 40 μm or more and 60 μm or less. It is preferable that there is.

[0039] The permeation portion 22b permeates the cathode gas diffusion layer 14 and contacts the sheet portion 22a with the cathode gas diffusion layer 14. The layer has adhesiveness to bond the diffusion layer 14. The penetration portion 22b is lower than the sheet portion 22a. The material is made of a material having a melting point. By heating the material, the penetration portion 22b is preferentially melted. The gas can be fluidized and allowed to permeate the cathode gas diffusion layer 14. The degree of penetration (penetration depth) of the penetration portion 22b into the cathode gas diffusion layer 14 is limited. However, in the case where the MPL 14b is provided on the cathode gas diffusion layer 14 as in this embodiment, In particular, it is preferable that the permeation portion 22b extends beyond the MPL layer 14b to the diffusion member 14a. This allows for a secure connection.

[0040] As shown in FIG. 3 and FIG. 4, the permeation portion 22b is formed on one surface (cathode) of the sheet portion 22a. The sheet portion 22 may be disposed over the entire surface of the sheet portion 22 (the surface on the gas diffusion layer 14 side). a may be provided intermittently on one surface of the support 23, or may be provided on the half of the one surface on the support 23 side. It may be disposed on a surface.

[0041] The material constituting the permeation portion 22b dissolves and permeates into the cathode gas diffusion layer 14, forming the sheet portion There are no particular limitations as long as the adhesive has the ability to bond 22a and the cathode gas diffusion layer 14. However, due to its relatively low melting point and excellent hydrolysis resistance, polyethylene, Polypropylene is preferably used. In order to increase the adhesion with the MPL 14b, the material constituting the penetration portion 22b is epoxy. By copolymerizing oxy groups, hydroxyl groups, etc. with polyethylene and polypropylene, Additives consisting of a group, a hydroxyl group, or an amide group may also be added. In addition, a compatibilizer may be used to improve the adhesion between the sheet portion 22a and the permeation portion 22b. can.

[0042] 1.2d.Effects When one end of the cover sheet is placed between the cathode gas diffusion layer and the membrane electrode assembly, Due to the thickness of the bar sheet, a space like C in Fig. 4 is generated. This is because the cover sheet The thicker the space, the larger the membrane electrode assembly and the It was discovered that this was the cause of damage to the cathode gas diffusion layer. On the other hand, the cover sheet needs a portion for sealing and a portion for adhesion as described above. Each of them needs a certain thickness to ensure its function. So what about the space C? However, it tends to become larger. In contrast, according to the present disclosure, the portion of the cover sheet for adhesion (permeation portion 22b) Since the cathode gas diffusion layer 14 can be formed inside the cathode gas diffusion layer 14, the space C is formed. The thickness of the cover sheet 22 can be reduced by only the sheet portion 22a. The space C between the tip of 22a on the membrane electrode assembly side and the cathode gas diffusion layer 14 is reduced. This prevents damage to the membrane electrode assembly and the cathode gas diffusion layer. This reduces the possibility of damage to the components and suppresses the leakage of reaction gases caused by such damage. At this time, the permeation portion 22b passes through the MPL 14b of the cathode gas diffusion layer 14 and enters the diffusion member 1 If it reaches 4a, more reliable adhesion and sealing can be achieved.

[0043] 1.2e. Other outer periphery shapes 1 FIG. 5 is a diagram for explaining another example of the shape of the outer periphery. FIG. 5 is a diagram from the same viewpoint as FIG. In the example of FIG. 5, the end face of the cathode catalyst layer 13 is located at the same position as the end face of the electrolyte membrane 12. In this case, the sheet portion 22a of the cover sheet 22 is laminated on the electrolyte membrane 12. There is no part that is in contact with the cathode catalyst layer 13 . Even in this form, the same effects as those described above can be obtained.

[0044] 1.2f. Other outer periphery shapes 2 FIG. 6 is a diagram for explaining another example of the shape of the outer periphery. In the example of FIG. 6, the sheet portion 22a of the cover sheet 22 is The end portion is provided with a tapered portion 22c which is a tapered protrusion. In addition, by arranging the space C so as to fill a part of the space, the space C can be further reduced. , the above-mentioned effects become even more pronounced.

[0045] 1.2g. Cover sheet placement As described above, the cover sheet 22 is permeated with the permeation portion 22b into the cathode gas diffusion layer 14. The method of arranging the markers is not particularly limited, but can be, for example, as follows. A diagram for explaining this is provided below.

[0046] First, as shown in FIG. 7, the cover sheet 22 is attached to the end of the surface of the support 23 and to the cathode. The sheet portion 22a is placed so as to contact the edge of the medium layer 13, and a cover sheet is placed on the sheet portion 22a. The cathode gas diffusion layer 14 is disposed on the permeation portion 22b side of the MPL 14b so as to be in contact with the MPL 14b. do. Next, while heating the infiltrated portion 22b to a temperature at which it softens and melts so that only the infiltrated portion 22b has fluidity, As shown by the straight arrows in FIG. 7, a pressing force is applied in the stacking direction of each layer. permeates into the cathode gas diffusion layer 14, and the layer configuration according to each of the above examples can be obtained.

[0047] At this time, the cover sheet 2 before the permeation portion 22b permeates into the cathode gas diffusion layer 14 The thickness of 2 is preferably about 20 μm to 100 μm from the viewpoint of ensuring mechanical strength. It is more preferable that the thickness is 40 μm to 100 μm, and the space C can be made smaller while ensuring mechanical strength. From this viewpoint, the thickness is more preferably 40 μm to 80 μm.

[0048] 2.Fuel cell The fuel cell 30 is a stack of a plurality of the above-mentioned power generating unit cells 10 (approximately 50 to 400 sheets). It is a member that collects electricity from a number of power generating unit cells 10. FIG. 8 shows the outline of its configuration. The fuel cell 30 includes a stack case 31, an end plate 32, and a plurality of power generating unit cells. 10, a current collecting plate 34, and a biasing member 35.

[0049] The stack case 31 contains a plurality of stacked power generating unit cells 10, a current collector plate 34, and a biasing The stack case 31 is a housing that houses the member 35 inside. In this embodiment, the stack case 31 is a rectangular cylindrical One end is open and the other end is closed, and a plate-shaped The piece projects out and forms a flange 31a.

[0050] The end plate 32 is a plate-shaped member that closes the opening of the stack case 31. The overlapping portion of the case 31 and the flange 31a is secured to the stack case 31 by bolts, nuts, etc. An end plate 32 is fixed to the stack case 31 so as to cover the stack case 31 .

[0051] The power generating unit cell 10 is as described above. A plurality of such power generating unit cells 10 are stacked to form a At this time, the power generating unit cell 10 adjacent to the cathode separator 15 is The anode separator 18 of the cell 10 is placed so as to overlap the cathode separator The grooves 15b of the anode separator 15 and the grooves 18b of the anode separator 18 overlap to form a cooling water flow path. will be done.

[0052] The current collector 34 is a member that collects current from the stacked power generating unit cells 10. 34 are disposed at one end and the other end of the stack of the power generating unit cells 10, one of which is a positive The other is a positive electrode and the other is a negative electrode. A terminal (not shown) is connected to the current collector 34, and the current collector 34 is electrically connected to the outside. It is structured so that this can be done.

[0053] The biasing member 35 is housed inside the stack case 31 and biases the stack of the power generating unit cells 10. The biasing member applies a pressing force in the stacking direction. For example, a disc spring can be used as the biasing member. Cut.

[0054] 3.Other In the above explanation, each member on the cathode side is referred to as "first" and each member on the anode side is referred to as "second." However, the cathode side may be the "second" and the anode side may be the "first." The same effect can be obtained even if the above is replaced. [Explanation of symbols]

[0055] 10 Power generating unit cell 11 Power Generation Department 12 Electrolyte membrane 13 Cathode catalyst layer 14 Cathode gas diffusion layer 15 Cathode separator 16 Anode catalyst layer 17 Anode gas diffusion layer 18 Anode separator 21 Outer periphery 22 Cover Sheet 22a Seat section 22b Penetration part 23 Support 23a Base material 23b Adhesive layer 30 Fuel Cell

Claims

1. a membrane electrode assembly including a first catalyst layer, a second catalyst layer, and an electrolyte membrane disposed between the first catalyst layer and the second catalyst layer; a first gas diffusion layer that is laminated on the first catalytic layer, the first gas diffusion layer having a diffusion member and a microporous layer provided on a surface of the diffusion member facing the first catalytic layer, and at least a part of an outer circumferential edge of the first gas diffusion layer being provided beyond an outer circumferential edge of the membrane electrode assembly; a second gas diffusion layer laminated on the second catalyst layer; a support disposed around at least a portion of the periphery of the membrane electrode assembly; a cover sheet disposed between the first gas diffusion layer and the membrane electrode assembly so as to bridge the support and at least one end of the electrolyte membrane and the first catalyst layer; The cover sheet is a sheet portion which is a layer on the membrane electrode assembly side; A permeation portion is laminated on the sheet portion and permeates through the microporous layer of the first gas diffusion layer and the microporous layer to the diffusion member. fuel cell.

2. A fuel cell as described in claim 1, wherein the sheet portion has a tapered protrusion at the end facing the membrane electrode assembly.

3. 3. The fuel cell according to claim 1, wherein an end face of said support and an end face of said membrane electrode assembly are disposed opposite to each other with a gap therebetween.

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