Manufacturing method of fuel cell

Abstract

To provide a method for manufacturing fuel cell cells that are easy to miniaturize. [Solution] A method for manufacturing a fuel cell cell comprising a gasket bonded to the surface of a first separator by a primer, and an adhesive layer for bonding with a second separator on the back surface of the first separator, wherein the gasket has an extended portion that extends along the surface of the first separator, and a mold that heats and presses the first separator for bonding with the adhesive layer presses the extended portion.

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing a fuel cell. [Background technology]

[0002] Patent Document 1 discloses a method for manufacturing a fuel cell seal body, in which a rubber gasket, which is in close contact with a metal member via a primer, is heated and bonded while being compressed and fixed. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-183198 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Around the gasket, there may be burrs attached to the gasket or primer used to bond the gasket to the separator. When the adhesive sheet between the separators is pressed and heated by the mold, these burrs and primer may come into contact with the mold. Direct contact between the mold and the burrs or primer can cause a sealing failure, so it is necessary to separate the gasket and the mold to avoid this. This separation requires the fuel cell to be made larger, which is a problem as fuel cell cells tend to become larger.

[0005] In light of the above issues, this disclosure aims to provide a method for manufacturing fuel cell cells that are easily miniaturized. [Means for solving the problem]

[0006] This application discloses a method for manufacturing a fuel cell cell, wherein a gasket bonded to the surface of a first separator by a primer is placed on the surface of the first separator, and an adhesive layer for bonding with a second separator is provided on the back surface of the first separator, the gasket having an extended portion that extends along the surface of the first separator, and the mold used to heat and press the first separator for bonding with the adhesive layer presses the extended portion. [Effects of the Invention]

[0007] According to this disclosure, by pressing and heating the mold from above the extended portion of the gasket, burrs and primer do not come into contact with the mold, eliminating the need to allocate space to avoid them, thus facilitating the miniaturization of the fuel cell cell. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is an exploded perspective view of the fuel cell cell 10. [Figure 2] Figure 2 is a plan view of the fuel cell cell 10. [Figure 3] Figure 3 is a conceptual diagram illustrating the layer structure of the outer periphery 21 of the fuel cell cell 10. [Figure 4] Figure 4 is a diagram illustrating the manufacturing process of the fuel cell cell 10. [Figure 5] Figure 5 illustrates another example of the form. [Modes for carrying out the invention]

[0009] 1. Fuel cell Figures 1 to 3 show diagrams illustrating one configuration of a fuel cell cell 10. A fuel cell cell 10 is a unit element for generating electricity by supplying hydrogen and oxygen (air), and multiple such fuel cell cells 10 are stacked to constitute a fuel cell. Figure 1 is an exploded perspective view of the fuel cell cell 10, and Figure 2 is a plan view of the combustion battery cell 10. Figure 3 is a diagram illustrating the layer structure of the outer periphery 21 of the fuel cell cell 10. In each figure, the directions of the three-dimensional orthogonal coordinate system are represented by arrows. Here, in the in-plane direction of the fuel cell, which is flat as a whole, the x-direction is the direction from the inlet side to the outlet side of the fluid, and the y-direction is the direction perpendicular to the x-direction. The z-direction is the stacking direction (thickness direction) of each member of the fuel cell having a stacked structure.

[0010] 1.1. Power generation section The power generation section 11 is a portion that contributes to power generation in the portion surrounded by the dotted line in FIG. 2, for example, and is formed by stacking a plurality of layers. The power generation section 11 of the fuel cell 10 is as known. One side is a cathode (oxygen supply side) and the other side is an anode (hydrogen supply side) with an electrolyte membrane interposed therebetween. On the cathode side, a cathode catalyst layer, a cathode diffusion layer, and a cathode separator 15 are stacked in this order from the electrolyte membrane side. On the other hand, the anode includes an anode catalyst layer, an anode diffusion layer, and an anode separator 18 in this order from the electrolyte membrane side. Incidentally, a laminate composed of an electrolyte membrane, a cathode catalyst layer, a cathode diffusion layer, an anode catalyst layer, and an anode diffusion layer may be referred to as a membrane electrode assembly. The thickness of the membrane electrode assembly is typically about 0.4 mm, and the thickness of the fuel cell 10 in the power generation section 11 is typically about 1.3 mm. The cathode separator 15 and the anode separator 18 constitute a pair of separators, and a membrane electrode assembly is disposed therebetween. Each layer can be configured as known, for example, as follows.

[0011] [Electrolyte membrane] The electrolyte membrane is a solid polymer thin film that exhibits good proton conductivity in a wet state. For example, it is composed of a fluorine-based ion exchange membrane. For example, a carbon-fluorine-based polymer can be used, and specifically, perfluoroalkylsulfonic acid-based polymers (Nafion (registered trademark)) and the like can be mentioned.

[0012] [Cathode catalyst layer] The cathode catalyst layer is a layer containing a catalyst metal in which the catalyst metal is supported on a support. Examples of catalyst metals include Pt, Pd, Rh, or alloys containing these. Examples of support materials include carbon particles made from carbon supports, more specifically glassy carbon, carbon black, activated carbon, coke, natural graphite, and artificial graphite.

[0013] [Anode catalyst layer] The anode catalyst layer, like the cathode catalyst layer, is a layer containing a catalyst metal in the form of the catalyst metal supported on a support. For example, the catalyst metal can be Pt, Pd, Rh, or alloys containing these. The support can be a carbon support, more specifically carbon particles consisting of glassy carbon, carbon black, activated carbon, coke, natural graphite, and artificial graphite.

[0014] [Cathode diffusion layer] The cathode diffusion layer can be made of, for example, a conductive porous material. More specific examples include carbon porous materials (carbon paper, carbon cloth, glassy carbon, etc.) and metal porous materials (metal mesh, foamed metal).

[0015] [Anode diffusion layer] The anode diffusion layer can be composed of, for example, a conductive porous material. More specific examples include carbon porous materials (carbon paper, carbon cloth, glassy carbon, etc.) and metal porous materials (metal mesh, foamed metal).

[0016] [Cathode separator (first separator)] The cathode separator 15 is the first separator in this form, and together with the anode separator 18 which is the second separator, they form a pair of separators. The cathode separator 15 is a member for supplying a reaction gas (air in this form) to the cathode diffusion layer, and has plural grooves on the surface facing the cathode diffusion layer, and these grooves function as reaction gas flow paths. The shape of the grooves is not particularly limited as long as the reaction gas can be appropriately supplied to the cathode diffusion layer, and an example is a type in which a plate-shaped member is formed into a wave shape as in this form. At that time, the plate thickness is typically 0.1 mm to 0.2 mm, and the height of the unevenness is typically about 0.5 mm. When it is wave-shaped, grooves are formed on the opposite side across the cathode separator 15 between adjacent grooves, and this functions as a cooling water flow path.

[0017] Also, as can be seen from FIG. 1, the cathode separator 15 has an air inlet hole A at a position extending from the power generation unit 11 to the outside and at a part that is one end side of the groove. in , a cooling water inlet hole W in , a hydrogen outlet hole H out provided, and at a part that is the other end side of the groove, there are an air outlet hole A out , a cooling water outlet hole W out , a hydrogen inlet hole H in provided. Here, the groove for air communicates with the air inlet hole A in , the air outlet hole A out , and the groove for cooling water communicates with the cooling water inlet hole W in , the cooling water outlet hole W out .

[0018] The material constituting the cathode separator 15 may be any material that can be used as a separator of a fuel cell, and may be a gas-impermeable conductive material. Examples of such materials include dense carbon in which carbon is compressed to make it gas-impermeable, and a pressed metal plate, etc.

[0019] [Anode Separator (Second Separator)] In this embodiment, the anode separator 18 is the second separator and, together with the cathode separator 15, which is the first separator, constitutes a pair of separators. The anode separator 18 is a component that supplies reaction gas (hydrogen) to the anode diffusion layer and has multiple grooves on the surface facing the anode diffusion layer, and these grooves function as reaction gas channels. The shape of the grooves is not particularly limited as long as the reaction gas can be appropriately supplied to the anode diffusion layer, and examples include a plate-shaped component formed in a corrugated shape, as in this embodiment. In that case, the plate thickness is typically 0.1 mm to 0.2 mm, and the height of the irregularities is typically about 0.4 mm. In the case of a wavy shape, in this embodiment, a groove is formed on the opposite side of the anode separator 18 between adjacent grooves, and this functions as a cooling water channel.

[0020] Furthermore, as can be seen in Figure 1, the anode separator 18 has an air inlet hole A at one end of the groove, extending outward from the power generation unit 11. in , cooling water inlet hole W in , hydrogen outlet hole H out An air outlet hole A is provided at the other end of the groove. out , cooling water outlet hole W out , hydrogen inlet H in A hydrogen inlet hole H is provided. in , hydrogen outlet hole H out The groove for the cooling water is connected to the cooling water inlet hole W. in , cooling water outlet hole W out It is connected to [the other device].

[0021] The material constituting the anode separator 18 may be any material that can be used as a separator in a fuel cell cell, and may be a gas-impermeable conductive material. Examples of such materials include dense carbon that has been compressed to be gas-impermeable, and press-formed metal plates.

[0022] [Power generation by the power generation unit] As is well known, the fuel cell cell 10 described above generates electricity as follows. When hydrogen is supplied from the groove of the anode separator 18, the hydrogen passes through the anode diffusion layer and forms protons (H) in the anode catalyst layer. + ) and electrons (e - The protons are broken down into protons and electrons, and the electrons pass through the electrolyte membrane and the conductive wires leading to the outside, with each reaching the cathode catalyst layer. Here, oxygen (air) is supplied to the cathode catalyst layer from the grooves of the cathode separator 15 via the cathode diffusion layer, and water (H2O) is generated in the cathode catalyst layer by the protons, electrons and oxygen. The generated water passes through the cathode diffusion layer and reaches the grooves of the cathode separator 15, where it is discharged. In other words, the fuel cell cell 10 utilizes the flow of electrons through conductive wires connecting the anode catalyst layer to the outside as electric current.

[0023] 1.2. Outer perimeter The outer periphery 21 is the outer periphery of the fuel cell cell 10, located outside the power generation unit 11 enclosed by a dotted line in Figure 2. Although it does not contribute to power generation, it is responsible for supplying various fluids to the power generation unit, collecting fluids from the power generation unit, and sealing. The outer periphery 21 is made up of multiple layers stacked together, as shown in Figure 3, which illustrates the layer structure (BB cross-section) of the outer periphery 21. Specifically, in this embodiment, the outer periphery 21 has the following configuration.

[0024] [Resin sheet] In the outer periphery 21, a resin sheet 23 is placed between a pair of separators, the cathode separator 15 and the anode separator 18, and the resin sheet 23 seals the inside of the fuel cell cell 10. As can be seen from Figure 1, the resin sheet 23 is arranged to surround the membrane electrode assembly. The resin sheet 23 functions as a sealing member that seals the space between the cathode separator 15 and the anode separator 18 on the outer periphery 21 of the fuel cell cell 10. The resin sheet 23 comprises a base material 24, an adhesive layer 25 positioned on one side of the base material 24 (the side facing the cathode separator), and an adhesive layer 26 positioned on the other side of the base material 24 (the side facing the anode separator). The adhesive layer 25 adheres to the cathode separator 15, and the adhesive layer 26 adheres to the anode separator 18, thereby sealing the inside of the power generation unit 11.

[0025] The base material 24 is formed from a thermoplastic resin material that has electrical insulation and airtightness and a relatively high melting point. Examples of such materials include polyethylene naphthalate, polyphenylene ether, and polyphenylene sulfide. The thickness of the base material 24 is not particularly limited, but can be between 0.05 mm and 0.25 mm. The adhesive layers 25 and 26 are composed of adhesive and tack.

[0026] [gasket] In the outer periphery 21, a gasket 40 is placed on one of the separators of the fuel cell cell 10 (the cathode separator 15, which is the first separator in this embodiment). The gasket 40 is bonded to the separator by a primer. The gasket 40 is positioned on the side of the separator opposite to the side (back side) where the membrane electrode assembly and resin sheet are arranged (i.e., the side facing the adjacent fuel cell cells 10 to be stacked, the front side), and functions as a sealing material between adjacent fuel cell cells 10 when multiple fuel cell cells 10 are stacked. Therefore, the gasket 40 is a frame-shaped sheet member positioned along the outer periphery 21, as shown in Figures 1 and 2 (shown with hatching in Figure 2).

[0027] In this embodiment, the gasket 40 has a main body 40a and an extended portion 40b that extends from the main body 40a toward the outer peripheral end of the fuel cell cell 10.

[0028] The main body 40a functions as a sealing material that seals between adjacent fuel cell cells 10. In this embodiment, the cross-sectional shape of the main body 40a is not particularly limited as long as it is used for gaskets, but for example, it has a trapezoidal cross-section as in this embodiment. In this case, the longer lower base is the side that is bonded to the separator with a primer. Other cross-sectional shapes include, for example, rectangles, squares, triangles, semicircles, semi-ellipses, etc. Since the main body 40a should have both sealing properties and flexibility, it is preferable that it be made of an elastic material. The specific material of the elastic material is not particularly limited, but examples include ethylene propylene rubber, fluororubber, and silicone rubber.

[0029] In this embodiment, as can be seen in Figure 3, the extended portion 40b is a thin, sheet-like portion that extends in the y-direction and x-direction along the surface of the cathode separator 15 from the end of the side surface (the surface that forms the thickness) of the main body 40a that is on the cathode separator 15 side. In this embodiment, the main body 40a and the extended portion 40b are integrated. The thickness (size in the z direction) of the extended portion 40b is not particularly limited, but can be approximately 10 μm to 500 μm. Furthermore, the size p of the extension of the extended portion 40b in the direction away from the main body 40a (the y direction in Figure 3, towards the outer edge of the fuel cell cell 10) should be such that a surface that can be pressed by a mold is formed, as will be described later.

[0030] The extended portion 40b may be made of the same material as the main body 40a, but it may also be made of a different material. If it is made of a different material, resin is an example.

[0031] 2. Method for manufacturing fuel cell and its effects The fuel cell can be constructed in the conventional manner, except for the step of bonding the pair of separators described below. The bonding of the pair of separators is performed as follows. A diagram for explanation is shown in Figure 4. Figure 4 is a view from the same perspective as Figure 3.

[0032] As shown in Figure 4, when bonding and joining a pair of separators (cathode separator 15 and anode separator 18) with adhesive layers 25 and 26, heating and pressing (pressure) are performed simultaneously by pressing with a heated mold 50 as indicated by arrow F. This bonds the pair of separators together with adhesive layers 25 and 26. In this manufacturing method, the mold 50 presses against the extended portion 40b provided on the gasket 40. As a result, even if the mold 50 presses near the gasket body 40a, burrs and primer do not come into contact with the mold and are not pressed against it. Therefore, it is not necessary to move the mold far away from the gasket body as in the conventional method, and the size of the fuel cell can be kept down. In addition, if the extended portion 40b is made of a highly flexible material such as rubber or resin, the surface contact by the mold will improve, and the sealing performance will also improve.

[0033] 3. Other forms Figure 5 shows a diagram illustrating another configuration. In the configuration of Figure 5, the main body 40a and the extended portion 40b of the gasket 40 are separated. Even if the extended portion 40b is separated from the main body 40a in this way, if the distance is small, the same effect as the configuration described above can be obtained in comparison to the conventional configuration. [Explanation of Symbols]

[0034] 10...Fuel cell, 11...Power generation unit, 15...Cathode separator, 18...Anode separator, 21...Outer periphery, 23...Resin sheet, 40...Gasket, 40a...Main body, 40b...Extended section

Claims

[Claim 1] A method for manufacturing a fuel cell cell comprising a gasket bonded to the surface of a first separator by a primer, and an adhesive layer for bonding with a second separator on the back surface of the first separator, The gasket has an extended portion that extends along the surface of the first separator, The mold for heating and pressing the first separator for bonding by the adhesive layer presses the extended portion, A method for manufacturing fuel cell cells.

Images