Fuel cell, fuel cell

Abstract

The present invention provides a fuel cell that can suppress the backflow of generated water into the edge region. [Solution] A fuel cell cell comprising a separator having rib portions that are concave on the flow path side in the edge region surrounding the flow path of the power generation region and the flow path of the non-power generation region, and a gas diffusion layer provided in the power generation region, wherein a sealing material is provided in at least a part of the rib portion near the hydrogen outlet hole.

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a separator for a fuel cell having a convex portion (a concave portion when viewed from the flow path side) formed on the edge region. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-186052 [Overview of the project] [Problems that the invention aims to solve]

[0004] Water generated from the hydrogen outlet manifold of the separator flows back into the flow path, entering the space between the separator and the gas diffusion layer, causing the generated water to accumulate in the convex parts (concave parts when viewed from the flow path side). This accumulated generated water contains, for example, Fe leached from the separator, which accelerates the deterioration of the electrolyte membrane.

[0005] In light of the above issues, this disclosure aims to provide a fuel cell cell that can suppress the backflow of generated water into the edge region. [Means for solving the problem]

[0006] The present invention discloses a fuel cell cell comprising a separator having rib portions that are concave on the flow path side in the edge region surrounding the flow path of the power generation region and the flow path of the non-power generation region, and a gas diffusion layer provided in the power generation region, wherein a sealing material is provided in at least a part of the rib portion near the hydrogen outlet hole.

[0007] The sealing material may be placed in the gap between the gas diffusion layer and the separator within the rib section.

[0008] A fuel cell in which a plurality of the above fuel cells are stacked, wherein the fuel cells are arranged such that the portion where the sealing material is disposed is downward, is disclosed.

Effect of the Invention

[0009] According to the present disclosure, it is possible to suppress the generated water from flowing into the rib portion (edge region) by the sealing material.

Brief Description of the Drawings

[0010] [Figure 1] FIG. 1 is an exploded perspective view of the fuel cell 10. [Figure 2] FIG. 2 is a plan view of the fuel cell 10. [Figure 3] FIG. 3 is a conceptual diagram for explaining the layer structure in the power generation region 11 of the fuel cell 10. [Figure 4] FIG. 4 is a conceptual diagram for explaining the structure of the portion where the sealing material 26 is disposed.

Mode for Carrying Out the Invention

[0011] 1. Basic Structure of Fuel Cell FIGS. 1 to 3 show diagrams for explaining the basic structure of the fuel cell 10 according to one embodiment. The fuel cell 10 is a unit element for generating power by supplying hydrogen and oxygen (air), and a plurality of such fuel cells 10 are stacked to form a fuel cell. FIG. 1 is an exploded perspective view of the fuel cell 10, and FIG. 2 is a plan view of the fuel cell 10 (in FIG. 2, the hydrogen flow path formed in the anode separator 18 is shown by a dotted line). Further, FIG. 3 is a diagram for explaining the layer structure in the power generation region 11 of the fuel cell 10.

[0012] 1.1. Power Generation Region The power generation region 11 is a portion that contributes to power generation, and as shown in FIG. 3 representing the layer structure in the power generation region 11 (a part of the A-A cross section in FIG. 2), a plurality of layers are stacked. In the power generation area 11 of the fuel cell 10, on one side of the electrolyte membrane 12 is the cathode (oxygen supply side), and on the other side is the anode (hydrogen supply side). The cathode is laminated with a cathode catalyst layer 13, a cathode gas diffusion layer 14, and a cathode separator 15 in this order from the electrolyte membrane 12 side. On the other hand, the anode includes an anode catalyst layer 16, an anode gas diffusion layer 17, and an anode separator 18 in this order from the electrolyte membrane 12 side. Note that the laminate composed of the electrolyte membrane 12, the cathode catalyst layer 13, the cathode gas diffusion layer 14, the anode catalyst layer 16, and the anode gas 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 10 in the power generation part 11 is typically about 1.3 mm. Each layer can be configured as known, for example, as follows.

[0013] 1.1a. Electrolyte membrane The electrolyte membrane 12 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)) etc. can be mentioned. The thickness of the electrolyte membrane 12 is not particularly limited, but it is 100 μm or less, preferably 50 μm or less, more preferably 10 μm or less.

[0014] 1.1b. Cathode catalyst layer The cathode catalyst layer 13 is a layer containing a catalyst metal in a form where the catalyst metal is supported on a carrier. For example, as the catalyst metal, Pt, Pd, Rh, or an alloy containing these can be mentioned. As the carrier, carbon carriers, more specifically, carbon particles composed of glassy carbon, carbon black, activated carbon, coke, natural graphite, and artificial graphite etc. can be mentioned.

[0015] 1.1c. 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.

[0016] 1.1d. Cathode Gas Diffusion Layer The cathode gas 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 gas diffusion layer as needed. The MPL is a thin coating applied to the cathode catalyst layer 13 side of the cathode gas diffusion layer 14. The MPL has the function of regulating moisture by being water-repellent or hydrophilic as needed. Typical MPLs consist mainly of water-repellent resins such as polytetrafluoroethylene (PTFE) and conductive materials such as carbon black.

[0017] 1.1e. Anode gas diffusion layer The anode gas 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).

[0018] 1.1f. Cathode Separator The cathode separator 15 is a component that supplies reaction gas (air in this embodiment) to the cathode gas diffusion layer 14. It has a plurality of grooves 15a on the surface facing the cathode gas diffusion layer 14, and these grooves function as reaction gas flow channels. The shape of the grooves is not particularly limited as long as the reaction gas can be properly supplied to the cathode gas diffusion layer 14. 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 around 0.5 mm. In the case of a wavy shape, a groove 15b is formed on the opposite side of the cathode separator 15 between adjacent grooves 15a, and this functions as a cooling water channel.

[0019] The material constituting the cathode separator 15 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 metal sheets such as press-formed stainless steel.

[0020] 1.1g. Anode separator The anode separator 18 is a component that supplies reaction gas (hydrogen) to the anode gas diffusion layer 17. It has a plurality of grooves 18a on the surface facing the anode gas 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 gas 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 around 0.4 mm. In the case of a wavy shape, in this embodiment, a groove 18b is formed on the opposite side of the adjacent groove 18a, with an anode separator 18 in between, and this functions as a cooling water channel.

[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 metal sheets such as press-formed stainless steel.

[0022] 1.1h. Power generation by power generation area As is well known, power is generated in the power generation region 11 of the fuel cell cell 10 described above, as follows. When hydrogen is supplied from the groove 18a of the anode separator 18, the hydrogen passes through the anode gas 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 gas diffusion layer 14, and water (H2O) is generated in the cathode gas catalyst layer 13 by the protons, electrons, and oxygen. The generated water passes through the cathode gas 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. Non-power generation sector The non-power generation region 20 is provided with a flow path (inflow flow path section 20a) that supplies air (oxygen) and hydrogen to the flow path of the power generation region 11 from each inlet hole provided in the edge region 21 (described later), and a flow path (outflow flow path section 20b) that discharges residual air, residual hydrogen, and generated water from the flow path of the power generation region 11 to each outlet hole provided in the edge region 21.

[0024] 1.2a. Inflow channel section The cathode separator 15 has an air inlet hole A formed in the edge region 21. in An inlet channel section is formed through the groove 15a of the power generation region 11, and the anode separator 18 has a hydrogen inlet hole H formed in the edge region 21. in An inlet channel section 20a is provided, in which a hydrogen flow path is formed through the groove 18a of the power generation region 11. Figure 2 shows the inlet channel section 20a of the anode separator 18. In the inflow channel section, as can be seen from Figure 2, there is an inlet hole (hydrogen inlet hole H in Figure 2). inA flow path (hydrogen flow path in Figure 2) is provided to extend from the source toward the power generation area 11, and a fluid (hydrogen in Figure 2) is supplied to the power generation area 11.

[0025] 1.2b. Outlet channel section The cathode separator 15 has an air outlet hole A formed in the edge region 21. out The outlet channel section has an air passage formed through the groove 15a of the power generation region 11, and the anode separator 18 has a hydrogen outlet hole H formed in the edge region 21. out An outlet channel section 20b is provided, in which a hydrogen channel is formed through the groove 18a of the power generation region 11. Figure 2 shows the outlet channel section 20b of the anode separator 18. In the outflow channel section, as can be seen in Figure 2, the power generation area 11 leads to the outlet hole (hydrogen outlet hole H in Figure 2). out A flow path (hydrogen flow path in Figure 2) is provided to collect fluid (hydrogen and generated water in Figure 2) from the power generation area 11, and the fluid is discharged towards it.

[0026] 1.3. Border Region The edge region 21 is formed to surround the power generation region 11 and the non-power generation region 20, and is a region that constitutes the outer periphery of the fuel cell cell 10, and is equipped with inlet holes, outlet holes, and is a part that is sealed.

[0027] 1.3a. Seal In the edge region 21, a resin sheet 23 (see Figure 1) is placed between the cathode separator 15 and the anode separator 18. The resin sheet 23 seals the inside of the fuel cell cell 10, and separates the anode side from the cathode side in the edge region 21 and the non-power generation region 20. As can be seen in Figure 1, the resin sheet 23 is positioned to surround the membrane electrode assembly. That is, the resin sheet 23 is sandwiched between the cathode separator 15 and the anode separator 18 in the edge region 21 of the fuel cell cell 10, sealing the inside. The resin sheet 23 includes a base material, an adhesive layer disposed on one surface (the surface on the cathode separator side) of the base material, and an adhesive layer disposed on the other surface (the surface on the anode separator side) of the base material. By adhering the adhesive layers to the cathode separator 15 and the anode separator 18 respectively, the power generation region 11 is sealed, and the cathode side and the anode side are separated in the edge region 21 and the non-power generation region 20.

[0028] 1.3b. Inlet·Outlet As can be seen from FIGS. 1 and 2, in the edge region 21, an air inlet hole A in , a cooling water inlet hole W in , and a hydrogen outlet hole H out are provided on one end side (the left side in FIG. 2) sandwiching the power generation region 11, and an air outlet hole A out , a cooling water outlet hole W out , and a hydrogen inlet hole H in are provided on the other end side (the right side in FIG. 2). Note that the groove 15a of the cathode separator 15 communicates with the air inlet hole A in and the air outlet hole A out through the resin sheet 23, and the groove 15b communicates with the cooling water inlet hole W in and the cooling water outlet hole W out in such a configuration. On the other hand, the groove 18a of the anode separator 18 communicates with the hydrogen inlet hole H in and the hydrogen outlet hole H [[ID=3l]] out through the resin sheet 23, and the groove 18b communicates with the cooling water inlet hole W in and the cooling water outlet hole W out in such a configuration.

[0029] 2. Structure of the part including the sealing material In this embodiment, it further has the following structure including a sealing material. FIG. 4 shows a conceptual diagram for explaining the structure on the anode separator 18 side of the part indicated by B in FIG. 2.

[0030] In the present disclosure, in the anode separator 18 in the edge region 21, a rib portion 25 that is concave on the surface on the hydrogen flow path side is disposed. This rib portion 25 prevents so-called side flow (fluid flowing in the edge region).

[0031] Here, hydrogen outlet hole H out In the vicinity, a sealing material 26 is placed on at least a portion of the rib portion 25 near the boundary between the power generation area 11 and the non-power generation area 20 (shown by a dashed line in Figure 4). Near the boundary between the power generation region 11 and the non-power generation region 20, as shown in Figure 4, a gap may exist between the anode gas diffusion layer 17 (shown as a dotted line in Figure 4) and the anode separator 18 due to material tolerances and placement tolerances. Through this gap, hydrogen outlet holes H, shown as thick dotted straight arrows in Figure 4, can be formed. out Backflow of generated water from the system sometimes flowed into the rib section 25. In response to this, the sealing material 26 is positioned to close the path to the rib section 25, thereby preventing the backflow of generated water from flowing into the rib section 25.

[0032] From this perspective, as shown in Figure 4, the sealing material 26 is located near the boundary between the power generation area 11 and the non-power generation area 20, specifically in the hydrogen channel or hydrogen outlet hole H out It is preferable to place it in the rib section closest to the water flow path. However, it is not limited to this, as the shape of the gap described above differs depending on the flow path shape, so the sealing material 26 should be placed in a location that can prevent the inflow of generated water into the rib section 25.

[0033] As mentioned above, the sealing material used is not particularly limited as long as it can close the flow path, but for example, potting agents can be used.

[0034] Here, the anode separator 18 has been described, but in the vicinity of the boundary between the power generation region 11 and the non-power generation region 20, gaps may also exist between the cathode gas diffusion layer 14 and the cathode separator 15 due to material tolerances, placement tolerances, etc. These gaps can also be addressed by applying a sealing material in the same way as with the anode separator 18.

[0035] Furthermore, as described above, a fuel cell is formed by stacking multiple fuel cell cells 10, but it is preferable that the sealing material 26 be placed in the lower flow path when the fuel cell is installed. This makes the above effect more pronounced with respect to the generated water that tends to accumulate at the bottom. [Explanation of symbols]

[0036] 10…Fuel cell, 11…Power generation area, 15…Cathode separator, 17…Anode gas diffusion layer, 18…Anode separator, 20…Non-power generation area, 21…Edge area, 23…Resin sheet, 25…Rib section, 26…Sealing material

Claims

1. A fuel cell comprising a separator having ribs that are concave on the flow path side in the edge region surrounding the flow path of the power generation region and the flow path of the non-power generation region, and a gas diffusion layer provided in the power generation region, A sealing material is placed in at least a portion of the rib portion near the hydrogen outlet hole. Fuel cell.

2. The fuel cell cell according to claim 1, wherein the sealing material is disposed in the gap between the gas diffusion layer and the separator in the rib portion.

3. A fuel cell comprising a plurality of stacked fuel cell cells as described in claim 1, The fuel cell is positioned such that the portion where the sealing material is placed is at the bottom. fuel cell.

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