Fuel cell separator, fuel cell

Abstract

The present invention provides a separator that can prevent the generated water from accumulating in the flow path near the hydrogen outlet. [Solution] A fuel cell separator having a recess in the edge region surrounding the flow path that is concave on the flow path side, wherein a bypass flow path is formed in the edge region near the hydrogen outlet hole through which a part of the hydrogen flow path communicates, and the recess is connected to the bypass flow path.

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a separator for a fuel cell having a protrusion formed on its edge region. [Prior art documents] [Patent Documents]

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

[0004] Water generated from the separator's hydrogen outlet manifold can backflow into the flow path, accumulating in the flow path near the hydrogen outlet. This generated water may contain, for example, iron leached from the separator, which can accelerate the degradation of the electrolyte membrane.

[0005] In view of the above issues, this disclosure aims to provide a separator that can suppress the accumulation of generated water in the flow path near the hydrogen outlet. [Means for solving the problem]

[0006] This application discloses a fuel cell separator having a recess in the edge region surrounding a flow path that is concave on the flow path side, wherein a bypass flow path is formed in the edge region near the hydrogen outlet hole, communicating with a part of the hydrogen flow path, and the recess is connected to the bypass flow path.

[0007] This application discloses a fuel cell in which a plurality of fuel cell cells, each comprising the above-mentioned fuel cell separator and electrolyte layer, are stacked, wherein the fuel cell cells are arranged so that the bypass flow path is at the bottom.

Advantages of the Invention

[0008] According to the present disclosure, the generated water flowing in the flow path can be returned from the edge region to the hydrogen outlet hole through the bypass flow path through the edge region provided with the concave portion, and the generated water can be accumulated in the flow path to reduce the influence on the electrolyte membrane.

Brief Description of the Drawings

[0009] [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 unit 11 of the fuel cell 10. [Figure 4] FIG. 4 is a view showing the vicinity of the bypass flow path 27 in the edge region 20.

Embodiments for Carrying Out the Invention

[0010] 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 unit 11 of the fuel cell 10.

[0011] 1. Power Generation Unit The power generation unit 11 is a part that contributes to power generation, and as shown in FIG. 3 representing the layer structure in the power generation unit 11 (a part of the A-A cross section in FIG. 2), a plurality of layers are stacked. In the power generation section 11 of the fuel cell 10, one side is the cathode (oxygen supply side) and the other side is the anode (hydrogen supply side) with the electrolyte membrane 12 interposed therebetween. On the cathode side, the cathode catalyst layer 13, the cathode diffusion layer 14, and the cathode separator 15 are laminated in this order from the electrolyte membrane 12 side. On the other hand, the anode includes the anode catalyst layer 16, the anode diffusion layer 17, and the anode separator 18 in this order from the electrolyte membrane 12 side. Note that the laminate 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 10 in the power generation section 11 is typically about 1.3 mm. Each layer can be configured as known, for example, as follows.

[0012] 1.1. 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)) and the like 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, and more preferably 10 μm or less.

[0013] 1.2. 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, 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.

[0014] 1.3. 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.

[0015] 1.4. 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.

[0016] 1.5. 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).

[0017] 1.6. Cathode Separator The cathode separator 15 is a component that supplies reaction gas (air in this embodiment) to the cathode diffusion layer 14. It has a plurality of grooves 15a on the surface facing the cathode diffusion layer 14, 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 cathode 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.

[0018] 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.

[0019] 1.7. Anode Separator The anode separator 18 is a component that supplies reaction gas (hydrogen) to the anode diffusion layer 17. It has a plurality of 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 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.

[0020] 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.

[0021] 1.8. Power generation by the power generation unit As is well known, the power generation unit 11 of 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.

[0022] 2. Border region The edge region 20 is located outside the power generation unit 11 and constitutes the outer periphery of the fuel cell cell 10. Although it does not contribute to power generation, it is the area where various fluids are supplied to the power generation unit 11, fluids are collected and discharged from the power generation unit, and a seal is applied.

[0023] 2.1. Seals In the edge region 20, 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 20. As can be seen from 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 20 of the fuel cell cell 10, sealing the inside. The resin sheet 23 comprises a base material, an adhesive layer positioned on one side of the base material (the cathode separator side), and an adhesive layer positioned on the other side of the base material (the anode separator side). The adhesive layers are bonded to the cathode separator 15 and the anode separator 18, respectively, sealing the inside of the power generation unit 11 and separating the cathode side and the anode side at the edge region 20.

[0024] 2.2.Inlet / outlet As can be seen from FIGS. 1 and 2, in the edge region 20, on one end side with the power generation unit 11 interposed therebetween (the left side in FIG. 2), an air inlet hole A in , a cooling water inlet hole W in , and a hydrogen outlet hole H out are provided, and on the other end side, an air outlet hole A out , a cooling water outlet hole W out , and a hydrogen inlet hole H in are provided. [[ID=1३]] 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 is configured to communicate with the cooling water inlet hole W in and the cooling water outlet hole W out . 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 out through the resin sheet 23, and the groove 18b is configured to communicate with the cooling water inlet hole W[[ID=२७]] in and the cooling water outlet hole W out .

[0025] 2.3. Inflow channel portion [[ID=३६]]The cathode separator 15 is provided with an inflow channel portion in which an air flow path is formed through the air inlet hole A in and the groove 15a of the power generation unit 11, and the anode separator 18 is provided with an inflow channel portion 21 in which a hydrogen flow path is formed through the hydrogen inlet hole H in and the groove 18a of the power generation unit 11. FIG. 2 shows the inflow channel portion 21 of the anode separator 18. In the inflow channel portion, as can be seen from FIG. 2, a flow path (hydrogen flow path in FIG. 2) is provided so as to spread from the inlet hole (hydrogen inlet hole H in FIG. 2 in ) toward the power generation unit 11, and fluid (hydrogen in FIG. 2) is supplied to the power generation unit 11.

[0026] 2.4. Outflow channel portion The cathode separator 15 is provided with an outflow channel portion in which an air flow path is formed through the air outlet hole A out and the groove 15a of the power generation unit 11, and the anode separator 18 is provided with an outflow channel portion in which a hydrogen flow path is formed through the hydrogen outlet hole H outAn outlet channel section 22 is provided, in which a hydrogen flow path is formed through the groove 18a of the power generation section 11. Figure 2 shows the outlet channel section 22 of the anode separator 18. In the outflow channel section, as can be seen in Figure 2, the power generation section 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 unit 11, and the fluid is discharged towards it.

[0027] 2.5. Structure of separators in the marginal region In this embodiment, the separator in the edge region 20 has the following structure. Figure 4 shows the part indicated by B in Figure 2 (hydrogen outlet hole H in the edge region 20). out A diagram illustrating the structure of the anode separator 18 (in its vicinity) is shown. While the anode separator 18 is described here, the cathode separator 15 can be considered in a similar manner.

[0028] In this disclosure, the anode separator 18 has a plurality of recesses 25 arranged in the edge region 20, which are concave on the side facing the hydrogen flow path. These recesses 25 prevent so-called side flow.

[0029] Furthermore, in this disclosure, the edge region 20 of the anode separator 18 has a hydrogen outlet hole H out A bypass channel 27 (shown by a thick straight arrow in Figure 4) is formed in the vicinity of the hydrogen channel, with a portion of the hydrogen channel communicating, and the recess 25 is connected to the bypass channel 27. More specifically, in this embodiment, as shown in Figure 4, branch channels 27a are provided, connecting to each of the two recesses 25 that are spaced apart from the hydrogen channel closest to the recess 25. The bypass channel 27 is formed by providing a bypass main channel 27b that crosses the two spaced recesses 25 on which the branch channels 27a are provided. The bypass main channel 27b may be connected to the recess 25 so as to cross it along its course.

[0030] This bypass channel 27 allows the generated water that flows into the hydrogen channel (for example, after power generation stops, the hydrogen outlet port H outThe generated water (which reaches the hydrogen channel due to backflow from the hydrogen channel) is bypassed through the bypass channel 27 and exits the edge region 20 through the hydrogen outlet hole H out This allows the system to return to its original state, and the generated water can accumulate in the hydrogen channel, reducing its impact on the electrolyte membrane.

[0031] Furthermore, as described above, a fuel cell is formed by stacking multiple fuel cell cells 10, but in the installed state of the fuel cell, it is preferable that the bypass channel 27 is positioned below the hydrogen channel. This makes the guidance of generated water into the bypass channel 27 smoother. [Explanation of symbols]

[0032] 10…Fuel cell, 11…Power generation section, 15…Cathode separator, 18…Anode separator, 20…Edge region, 21…Inflow channel section, 22…Outflow channel section, 23…Resin sheet, 25…Recess, 27…Bypass channel

Claims

1. A fuel cell separator having a recess in the edge region surrounding the flow path that is concave on the flow path side, A bypass channel is formed in the edge region, communicating with a portion of the hydrogen channel near the hydrogen outlet hole, and the recess is connected to the bypass channel. Separator for fuel cells.

2. A fuel cell comprising a plurality of fuel cell cells stacked, each having a fuel cell separator and an electrolyte layer as described in claim 1, The fuel cell is positioned such that the bypass channel is located downwards. fuel cell.

Images