fuel cell

Abstract

To provide a fuel cell with improved pressure resistance. [Solution] A fuel cell cell comprising an adhesive portion provided between a pair of separators and a sealing member provided on the opposite side of the separator surfaces bonded by the adhesive portion, wherein in a plan view, the end of the adhesive portion is located between the center of the most protruding part of the sealing member and its end.

Description

[Technical Field]

[0001] This disclosure relates to fuel cell cells. [Background technology]

[0002] Patent Document 1 discloses a fuel cell comprising a first sealing portion (adhesive sealing portion) provided on the outer circumference of an electrode assembly between a pair of gas separators and a second sealing portion (gasket) provided between adjacent single cells. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-192327 [Overview of the project] [Problems that the invention aims to solve]

[0004] If there is a distance between the adhesive seal and the gasket when viewed from above, the pressure resistance of the fuel cell cell may decrease.

[0005] In view of the above issues, this disclosure aims to provide a fuel cell cell capable of improving pressure resistance. [Means for solving the problem]

[0006] The present invention discloses a fuel cell cell comprising an adhesive portion provided between a pair of separators and a sealing member provided on the opposite side of the surface of the separators bonded by the adhesive portion, wherein, in a plan view, the end of the adhesive portion is located between the center and the end of the most protruding part of the sealing member. [Effects of the Invention]

[0007] According to this disclosure, the pressure resistance of the fuel cell cell is improved by reducing the distance between the adhesive portion and the sealing member. [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 illustrates another example. [Figure 5] Figure 5 illustrates an example that does not use a gasket. [Modes for carrying out the invention]

[0009] 1. Structure of a 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. Each figure shows arrows representing the directions in a three-dimensional Cartesian coordinate system. Here, the in-plane direction of the fuel cell, which is flat as a whole, is shown, with the x-direction being the direction from the fluid inlet to the outlet, and the y-direction being perpendicular to the x-direction. The plan view is seen in the xy plane. The z-direction is the stacking direction (thickness direction) of each component of the stacked fuel cell cell.

[0010] 1.1. Power Generation Section The power generation unit 11 is the part that contributes to power generation, for example, the area enclosed by the dotted line in Figure 2, and is made up of multiple layers stacked on top of each other. The power generation unit 11 of the fuel cell 10 is as known in the art. One side is the cathode (oxygen supply side) and the other side is the anode (hydrogen supply side) with an electrolyte membrane sandwiched therebetween. The cathode has a cathode catalyst layer, a cathode diffusion layer, and a cathode separator 15 laminated 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. Note that the laminate of the electrolyte membrane, the cathode catalyst layer, the cathode diffusion layer, the anode catalyst layer, and the 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 unit 11 is typically about 1.3 mm. The cathode separator 15 and the anode separator 18 constitute a pair of separators, and the membrane electrode assembly is disposed therebetween. Each layer can be configured as known in the art, 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 a form where the catalyst metal is supported on a carrier. For example, examples of the catalyst metal include Pt, Pd, Rh, or an alloy containing these. Examples of the carrier include carbon carriers, more specifically, carbon particles composed of 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)] In this embodiment, the cathode separator 15 is the first separator and, together with the anode separator 18, which is the second separator, constitutes a pair of separators. The cathode separator 15 is a component that supplies reaction gas (air in this embodiment) to the cathode diffusion layer and has multiple grooves on the surface facing the cathode 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 cathode 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 0.5 mm. In the case of a wavy shape, a groove is formed on the opposite side of the cathode separator 15 between adjacent grooves, and this functions as a cooling water channel.

[0017] Further, as can be seen from FIG. 1, the cathode separator 15 has an air inlet hole A at a position that extends from the power generation unit 11 to the outside and is at one end side of the groove, in a cooling water inlet hole W, in a hydrogen outlet hole H, out which are provided. At the other end side of the groove, there are an air outlet hole A out a cooling water outlet hole W, out and a hydrogen inlet hole H, in which are provided. Here, the groove for air communicates with the air inlet hole A in and the air outlet hole A, out and the groove for cooling water communicates with the cooling water inlet hole W in and 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 obtained by compressing carbon to make it gas-impermeable, and a press-molded metal plate, etc.

[0019] [Anode Separator (Second Separator)] The anode separator 18 is the second separator in this embodiment, and forms a pair of separators with the cathode separator 15 which is the first separator. The anode separator 18 is a member that supplies a reaction gas (hydrogen) to the anode diffusion layer, and has a plurality of grooves on the surface facing the anode 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 anode diffusion layer, and an example is a type in which a plate-like member is formed in a wave shape as in this embodiment. At that time, the plate thickness is typically 0.1 mm to 0.2 mm, and the height of the unevenness is typically about 0.4 mm. In the case of being wave-shaped, in this embodiment, grooves are formed on the opposite side across the anode separator 18 between adjacent grooves, and this functions as a cooling water flow path.

[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 disposed on one side of the base material 24 (the cathode separator side), and an adhesive layer 26 disposed on the other side of the base material 24 (the anode separator side).

[0025] 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. Here, the adhesion between the adhesive layers 25 and 26 and the separator is not achieved over the entire area. The adhesive area (adhesive part) is the area where heating and pressurization by a mold or the like have been performed (the adhesive part), indicated by q in Figure 3. Therefore, the adhesive area (adhesive part) q comprises the end q1 on the power generation part side and the end q2 on the outer circumference side.

[0026] 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.

[0027] [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 member 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).

[0028] The cross-sectional shape of the gasket 40 is not particularly limited as long as it is suitable for use as a gasket, but examples include those having 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 primer. Other cross-sectional shapes include, for example, rectangles, squares, triangles, semicircles, and semi-ellipses. Since the gasket 40 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, fluorocarbon rubber, and silicone rubber.

[0029] [Relationship between gasket and bonding area] In this embodiment, as shown in Figure 3, the end portion q1 of the adhesive area (adhesive part) q is positioned so that it falls within the range p (y-direction range p) from the center of the most protruding part of the gasket 40 to the end of the gasket 40 in a plan view (viewed from the direction indicated by arrow A in Figure 3). For gaskets with a triangular or semicircular cross-section, the most protruding part is a point, so the range p can be defined as the distance from that point to the end of the gasket. This allows for increased pressure resistance of fuel cell cells, leading to improved performance, or conversely, allows for lower adhesive strength to achieve the same pressure resistance, thus easing production control requirements.

[0030] Figure 4 shows an example illustrating a sheet-like extension 41 extending from the side of the gasket 40 along the separator surface. Figure 4 is a view from the same perspective as Figure 3. By providing the extension 41, the range p extends from the center of the most protruding part of the gasket 40 to the end of the extension 41, thereby widening the range p. This also allows for lower positional accuracy regarding the placement of the end q1, and further eases production control.

[0031] 2. Examples that do not involve gaskets Figure 5 shows a diagram illustrating a configuration without a gasket. In the configuration of Figure 5, instead of a gasket, a projection 50 is placed on the cathode separator 15, and another projection 50 is placed on the anode separator 18 on the opposite side of the resin sheet 23. When multiple fuel cell cells 10 are stacked, the projections 50 of adjacent fuel cell cells 10 are pressed against each other, and their elastic force causes them to adhere tightly, performing a sealing function. At least a portion of the adhered area may be welded by laser or the like.

[0032] In this example, as shown by the distance w in Figure 5, the range p can be set to 0.2 (calculated as p / w) from the outer peripheral end of the projection 50 to the outer peripheral end of the fuel cell cell 10, where the cathode separator 15 is in contact with the adhesive layer 25. [Explanation of Symbols]

[0033] 10…Fuel cell, 11…Power generation unit, 15…Cathode separator, 18…Anode separator, 21…Outer periphery, 23…Resin sheet, 40…Gasket (sealing member)

Claims

[Claim 1] A fuel cell comprising an adhesive portion provided between a pair of separators, and a sealing member provided on the opposite side of the surface of the separators bonded by the adhesive portion, In a plan view, the end of the adhesive portion is located between the center and the end of the most protruding part of the sealing member. Fuel cell.

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