fuel cell

Abstract

To provide a fuel cell that can suppress the deterioration of sealing performance even when a load is applied. [Solution] A fuel cell cell having an internal seal that is arranged on the outer circumference and joins and seals a pair of separators, wherein the separator has a rib that protrudes toward the internal seal, and the rib comprises a flat portion for arranging the internal seal, a first spring portion formed to bend at a right angle from both sides of the flat portion, an inclined portion inclined from the first spring portion, and a second spring portion provided on the side of the inclined portion opposite to the first spring portion and having the same structure as the first spring portion.

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a fuel cell having a cooling water channel structure formed by welding separators together. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-111552 [Overview of the project] [Problems that the invention aims to solve]

[0004] In the case of conventional designs, when the center of the flat section deforms into a concave shape, surface pressure loss in the rubber may occur, potentially leading to a decrease in sealing performance.

[0005] In view of the above issues, this disclosure aims to provide a fuel cell that can suppress a decrease in sealing performance even when a load is applied. [Means for solving the problem]

[0006] The present invention discloses a fuel cell cell having an internal seal arranged on the outer periphery and joining and sealing a pair of separators, wherein the separator has ribs protruding toward the internal seal, and the ribs include a flat portion for arranging the internal seal, a first spring portion formed to bend at a right angle from both sides of the flat portion, an inclined portion inclined from the first spring portion, and a second spring portion provided on the side of the inclined portion opposite to the first spring portion and having the same structure as the first spring portion. [Effects of the Invention]

[0007] According to this disclosure, even when a load is applied, the center of the flat portion of the rib can be prevented from collapsing, ensuring sufficient stroke and suppressing a decrease in sealing performance. [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 configuration in the power generation section 11 of the fuel cell cell 10. [Figure 4] Figure 4 is a conceptual diagram illustrating the layer structure in the outer periphery 21 of the fuel cell cell 10. [Figure 5] Figure 5 illustrates the outer periphery of the stacked structure of the fuel cell cell 10 in the fuel cell stack. [Figure 6] Figure 6 is a diagram illustrating the effect. [Modes for carrying out the invention]

[0009] 1. Fuel cell Figures 1 to 4 illustrate a fuel cell cell 10 in one configuration. The 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 form a fuel cell stack. 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 power generation section 11 of the fuel cell cell 10, and Figure 4 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 as follows: the x-direction is the direction from the fluid inlet to the outlet, and the y-direction is perpendicular to the x-direction. The z-direction is the stacking direction of each component of the stacked fuel cell.

[0010] 1.1. Power Generation Unit The power generation unit 11 is, for example, a portion contributing to power generation in the region enclosed by the dotted line in FIG. 2, and is formed by stacking a plurality of layers as shown in the layer configuration (part of the A-A cross section) of the power generation unit 11 in FIG. 3. In the power generation unit 11 of the fuel cell cell 10, with the electrolyte membrane 12 interposed therebetween, one side is a cathode (oxygen supply side) and the other side is an anode (hydrogen supply side). In the cathode, a cathode catalyst layer 13, a cathode diffusion layer 14, and a cathode separator 15 are stacked in this order from the electrolyte membrane 12 side. On the other hand, the anode includes an anode catalyst layer 16, an anode diffusion layer 17, and an anode separator 18 in this order from the electrolyte membrane 12 side. Note that the stacked body composed of the electrolyte membrane 12, the cathode catalyst layer 13, the cathode diffusion layer 14, the anode catalyst layer 16, and the anode diffusion layer 17 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 cell 10 in the power generation unit 11 is typically about 1.3 mm. Each layer can be configured in a known manner, for example, as follows.

[0011] [Electrolyte Membrane] The electrolyte membrane 12 is a solid polymer thin film that exhibits good proton conductivity in a wet state. It is composed of, for example, a fluorine-based ion exchange membrane, and for example, a carbon-fluorine-based polymer can be used, and specific examples include perfluoroalkylsulfonic acid-based polymer (Nafion (registered trademark)) and the like. The thickness of the electrolyte membrane 12 is not particularly limited, but is 100 μm or less, preferably 50 μm or less, more preferably 10 μm or less.

[0012] [Cathode Catalyst Layer] The cathode catalyst layer 13 is a layer containing a catalytic metal in a form where the catalytic metal is supported on a carrier. For example, examples of the catalytic metal include Pt, Pd, Rh, or alloys containing these. Examples of the carrier include carbon carriers, more specifically carbon particles composed of glassy carbon, carbon black, activated carbon, coke, natural graphite, artificial graphite and the like.

[0013] [Anode Catalyst Layer] The anode catalyst layer 16, like the cathode catalyst layer 13, 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 14 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). A microporous layer (MPL) may be provided in the cathode diffusion layer as needed. The MPL is a thin film coating applied to the cathode catalyst layer 13 side of the cathode diffusion layer 14. The MPL has the function of regulating moisture by being water-repellent or hydrophilic as needed. Typical MPLs consist mainly of a water-repellent resin such as polytetrafluoroethylene (PTFE) and a conductive material such as carbon black.

[0015] [Anode diffusion layer] The anode diffusion layer 17 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).

[0016] [Cathode separator] The cathode separator 15 is a member that supplies a reactive gas (air in the present embodiment) to the cathode diffusion layer 14, and has a plurality of grooves 15a on the surface facing the cathode diffusion layer 14, and these grooves function as reactive gas flow paths. The shape of the grooves is not particularly limited as long as the reactive gas can be appropriately supplied to the cathode diffusion layer 14, and examples thereof include a form in which a plate-shaped member is formed into a corrugated shape as in the present embodiment. At that time, 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 corrugated shape, grooves 15b are formed on the opposite side across the cathode separator 15 between adjacent grooves 15a, and these function as cooling water flow paths.

[0017] Further, as can be seen from FIG. 1 and FIG. 2, the cathode separator 15 is provided with an air inlet hole A at a position extending outward from the power generation unit 11, at a portion on one end side of the grooves 15a and the grooves 15b in , a cooling water inlet hole W in , and a hydrogen outlet hole H out , and an air outlet hole A is provided at a portion on the other end side of the grooves 15a and the grooves 15b out , a cooling water outlet hole W out , and a hydrogen inlet hole H in . The grooves 15a communicate with the air inlet hole A in and the air outlet hole A out , and the grooves 15b communicate 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 for fuel cells, and may be a gas-impermeable conductive material. Examples of such a material include dense carbon obtained by compressing carbon to make it gas-impermeable, press-molded metal plates, and the like.

[0019] [Anode Separator] The anode separator 18 is a component that supplies reaction gas (hydrogen) to the anode diffusion layer 17. It has multiple grooves 18a on the surface facing the anode diffusion layer 17, 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 properly supplied to the anode diffusion layer 17. 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 corrugated shape, in this embodiment, grooves 18b are formed on the opposite side of the anode separator 18 between adjacent grooves 18a, and these function as cooling water channels.

[0020] Furthermore, as can be seen in Figure 1, the anode separator 18 has an air inlet hole A at one end of grooves 18a and 18b, located at a position that extends 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 groove 18a and groove 18b. out , cooling water outlet hole W out , hydrogen inlet H in A groove 18a is provided. Here, the groove 18a is the hydrogen inlet hole H in , hydrogen outlet hole H out It is connected to the cooling water inlet hole W, and groove 18b 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 18a of the anode separator 18, the hydrogen passes through the anode diffusion layer 17 and is converted into protons (H) in the anode catalyst layer 16. + ) and electrons (e - The protons are broken down into electrons and electrons, and the protons pass through the electrolyte membrane 12, while the electrons pass through conductive wires leading to the outside, each reaching the cathode catalyst layer 13. Here, oxygen (air) is supplied to the cathode catalyst layer 13 from the groove 15a of the cathode separator 15 via the cathode diffusion layer 14, and water (H2O) is generated in the cathode catalyst layer 13 by the protons, electrons, and oxygen. The generated water passes through the cathode diffusion layer 14 and reaches the groove 15a 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 16 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 4, 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] [Cell seal] In the outer periphery 21, an internal cell seal 23 is positioned between the cathode separator 15 and the anode separator 18 (a pair of separators), and the inside of the fuel cell cell 10 is sealed by the internal cell seal 23. As can be seen from Figure 1, the internal cell seal 23 is positioned to surround the membrane electrode assembly. The cell seal 23 functions as a sealing member that seals and 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 cell seal 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 is between 0.05 mm and 0.25 mm. The adhesive layers 25 and 26 are composed of adhesive and tack.

[0026] [Ribbed section] Furthermore, on the outer periphery 21, the cathode separator 15 and the anode separator 18 are each provided with ribs 30, which are projections that protrude in the z-direction toward the cell seal 23. The shape of the ribs 30 in this embodiment is as follows.

[0027] As can be seen in Figure 4, the rib 30 comprises a flat portion 30a, a first spring portion 30b, an inclined portion 30c, and a second spring portion 30d. Each portion has the following shape in the cross-section shown in Figure 4, and extends in the direction of the back / front of the paper in Figure 4 in this shape. The flat portion 30a has a flat surface that is positioned along the surface of the cell seal 23. Therefore, the flat surface of the flat portion 30a is laminated and bonded to the adhesive layer 25 and the adhesive layer 26. The first spring portion 30b is a piece that extends from each end of the flat portion 30a so as to bend at a right angle to the flat portion 30a and to separate from the cell seal 23. The inclined portion 30c is a piece that extends from the end of the first spring portion 30b opposite to the connection portion with the flat portion 30a, inclined to move away from the flat portion 30a and the first spring portion 30b. The inclined portion 30c only needs to be inclined in a part, and in this embodiment, the portion that connects to the first spring portion 30b and the second spring portion 30d has a part that is parallel to the flat portion 30a. The second spring portion 30d is a piece that extends from the end of the inclined portion 30c opposite to the connection portion with the first spring portion 30b in a direction perpendicular to the flat portion 30a (thickness direction, z direction). In other words, in this embodiment, the second spring portion 30d has the same form as the first spring portion 30b.

[0028] 2. Fuel cell stack 2.1.Overall structure A fuel cell stack is a component made up of multiple (approximately 50 to 400) of the fuel cell cells 10 described above, and collects current from multiple fuel cell cells 10. As is well known, a fuel cell stack comprises a stack case, end plates, multiple fuel cell cells 10, a current collector plate, and a biasing member.

[0029] 2.2. Laminated structure in the outer periphery Figure 5 shows the stacked structure of the fuel cell stack, focusing on the outer periphery 21 of the fuel cell cell 10. Figure 5 also shows the outer periphery of two adjacent fuel cell cells 10, as well as the adjacent cathode separator 15 and anode separator 18.

[0030] As can be seen in Figure 5, in the outer periphery 21 of the stacked fuel cell cells 10, the cathode separator 15 of one fuel cell 10 and the anode separator 18 of the other fuel cell 10 are stacked so that they overlap. At this time, the ribs 30 of the adjacent fuel cell cells 10 are arranged to overlap. The outer periphery 21 of adjacent fuel cell cells 10 is welded (welded section S) by laser welding at the overlapping portion of the cathode separator 15 of one fuel cell cell 10 and the anode separator 18 of the other adjacent fuel cell cell 10, which is the outer portion of both ends of the rib 30.

[0031] 3. Effects, etc. Figure 6 shows a diagram illustrating the effects of the fuel cell cell 10 of this embodiment. Figure 6(a) is a conventional example, and Figure 6(b) is an example of this embodiment. As shown by the straight arrows in Figure 6(a), when a force is applied in the stacking direction of the fuel cell stack, the conventional ribs deform as shown by the dotted lines in Figure 6(a), and a force that causes them to curve, as indicated by P, is likely to occur at the contact point with the cell seal. This weakens the sealing performance between the cell seal and the ribs, leading to a decrease in sealing performance. On the other hand, when a force is applied in the stacking direction of the fuel cell stack, as shown by the straight arrow in Figure 6(b), the rib 30 in this embodiment deforms as shown by the dotted line in Figure 6(b), and the contact portion (flat portion) with the cell seal 23 can be generally maintained flat as shown by Q. This maintains sealing performance between the cell seal 23 and the rib 30, and prevents a decrease in sealing performance. In this way, even when a load is applied, the stroke can be secured without the center of the flat portion of the rib becoming concave, and a decrease in sealing performance can be suppressed.

[0032] In the above-described embodiment, the rib included both the first spring portion and the second spring portion, but it is not limited to this, and the rib may be provided with either the first spring portion or the second spring portion. [Explanation of Symbols]

[0033] 10...Fuel cell cell, 11...Power generation unit, 15...Cathode separator, 18...Anode separator, 21...Outer periphery, 23...Internal cell seal, 30...Rib

Claims

[Claim 1] A fuel cell having an internal seal that is arranged on the outer periphery and joins and seals a pair of separators, The separator has ribs that protrude toward the cell seal, The aforementioned rib is A flat portion for arranging the cell-internal seal, A first spring portion is formed so as to bend at a right angle from both sides of the flat portion, An inclined portion that is inclined from the first spring portion, The inclined portion includes a second spring portion, which is provided on the side opposite to the first spring portion and has the same structure as the first spring portion, Fuel cell.

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