Fuel cell stack

Abstract

Provided is a fuel cell stack capable of suppressing the occurrence of displacement between fuel cell cells. A fuel cell stack is provided with at least a plurality of fuel cell cells and inter-cell seals sandwiched between the plurality of fuel cell cells, the plurality of fuel cell cells have ribs that come into contact with the inter-cell seals, and the ribs have a shape in which the ribs that face each other with the inter-cell seals therebetween engage with each other in adjacent fuel cell cells.

Description

Technical Field

[0001] This disclosure relates to fuel cell stacks having multiple fuel cell cells stacked together. Background Technology

[0002] Patent document 1 discloses a fuel cell stack in which adhesive sheets are arranged between fuel cell cells in a stacked fuel cell cell structure.

[0003] Patent document 2 discloses a fuel cell diaphragm with irregular ridges on the gas flow path.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2023-135771

[0005] Patent Document 2: Japanese Patent Application Publication No. 2017-111985

[0006] Traditional methods for preventing misalignment between fuel cell cells rely solely on the friction between the fuel cell cell and the bonding sheet. Under the application of strong force, misalignment can occur between the fuel cell cells. Summary of the Invention

[0007] In view of the above problems, the purpose of this disclosure is to provide a fuel cell stack that can suppress the generation of misalignment between fuel cell cells.

[0008] This application discloses a fuel cell stack, which includes at least a plurality of fuel cell cells and an inter-cell seal sandwiched between the plurality of fuel cell cells. The plurality of fuel cell cells have ribs that contact the inter-cell seal, and the ribs are in a shape in which the ribs of adjacent fuel cell cells, facing each other across the inter-cell seal, mesh with each other.

[0009] It can also be configured such that the ribs have inclined surfaces, and the opposing ribs mesh on the inclined surfaces.

[0010] According to this disclosure, by adding an engagement structure to the frictional force between the fuel cell cells and the cell-to-cell seals, it is possible to suppress the displacement of the fuel cell cells even when a stronger force is applied. Attached Figure Description

[0011] Figure 1 This is an exploded perspective view of fuel cell cell 10.

[0012] Figure 2 This is a top-down view of fuel cell cell 10.

[0013] Figure 3 This is a schematic diagram illustrating the layer structure of the power generation section 11 in the fuel cell cell 10.

[0014] Figure 4This is a schematic diagram illustrating the layer structure in the outer periphery 21 of the fuel cell cell 10.

[0015] Figure 5 This diagram illustrates another example of how ribs can be used.

[0016] Figure 6 This is a schematic diagram illustrating the structure of the fuel cell stack 50.

[0017] Figure 7 This diagram illustrates the outer periphery of the stacked structure of the fuel cell cell 10 in the fuel cell stack 50.

[0018] Explanation of reference numerals in the attached figures

[0019] 10… Fuel cell; 11… Power generation section; 15… Cathode diaphragm; 18… Anode diaphragm; 21… Outer periphery; 23… Resin sheet; 30, 31… Ribs; 30a, 31a… Engaging parts; 40… Inter-cell seal; 50… Fuel cell stack. Detailed Implementation

[0020] 1. Fuel cell

[0021] exist Figures 1-4 The diagram illustrates a fuel cell cell 10 involved in one method. 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.

[0022] Figure 1 This is an exploded 3D view of fuel cell cell 10. Figure 2 This is a top-down view of the fuel cell 10. Additionally, Figure 3 This diagram illustrates the layer structure of the power generation section 11 in the fuel cell cell 10. Figure 4 This diagram illustrates the layer structure of the outer periphery 21 in the fuel cell cell 10.

[0023] In the accompanying figures, arrows indicate the directions of the three-dimensional orthogonal coordinate system. Here, in the in-plane directions of the fuel cell cell, which is a flat plate as a whole, the x-direction is the direction from the fluid inlet side to the outlet side, and the y-direction is the direction orthogonal to the x-direction. The z-direction is the stacking direction of the components of the fuel cell cell, which is a stacked structure.

[0024] 1.1. Power Generation Department

[0025] For example, in the power generation section 11 Figure 2 The section enclosed by the dashed line in the middle is the part that helps generate electricity, in order to... Figure 3 The diagram shows the layered structure of the power generation unit 11 (part of the AA cross section), in which multiple layers are stacked.

[0026] In the power generation section 11 of the fuel cell cell 10, an electrolyte membrane 12 is sandwiched, with one side serving as the cathode (oxygen supply side) and the other as the anode (hydrogen supply side). The cathode, starting from the electrolyte membrane 12 side, comprises a cathode catalyst layer 13, a cathode diffusion layer 14, and a cathode separator 15 stacked sequentially. Conversely, the anode, starting from the electrolyte membrane 12 side, comprises an anode catalyst layer 16, an anode diffusion layer 17, and an anode separator 18 stacked sequentially. Furthermore, the laminate formed by the electrolyte membrane 12, cathode catalyst layer 13, cathode diffusion layer 14, anode catalyst layer 16, and anode diffusion layer 17 is sometimes referred to as a membrane electrode assembly (MEA). The MEA thickness is typically approximately 0.4 mm, and the thickness of the fuel cell cell 10 in the power generation section 11 is typically approximately 1.3 mm.

[0027] The layers can be constructed as is known, for example, as described below.

[0028] 1.1a. Electrolyte membrane

[0029] The electrolyte membrane 12 is a solid polymer film that exhibits good proton conductivity in a wetted state. For example, it is composed of a fluorine-based ion exchange membrane, and carbon-fluorine polymers can be used, specifically, perfluoroalkyl sulfonic acid polymers (Nafion (registered trademark)) etc.

[0030] The thickness of the electrolyte membrane 12 is not particularly limited, but is 100 μm or less, preferably 50 μm or less, and more preferably 10 μm or less.

[0031] 1.1b. Cathode catalyst layer

[0032] The cathode catalyst layer 13 is a layer containing a catalyst metal in the form of a catalyst metal supported on a carrier. Examples of catalyst metals include Pt, Pd, Rh, or alloys containing them. Examples of carriers include carbon supports, and more specifically, carbon particles composed of glassy carbon, carbon black, activated carbon, coke, natural graphite, and artificial graphite.

[0033] 1.1c. Anode catalyst layer

[0034] The anode catalyst layer 16 is similar to the cathode catalyst layer 13, and is a layer containing catalyst metal in the form of a catalyst metal supported on a carrier. Examples of catalyst metals include Pt, Pd, Rh, or alloys containing them. Examples of carriers include carbon supports, and more specifically, carbon particles composed of glassy carbon, carbon black, activated carbon, coke, natural graphite, and artificial graphite.

[0035] 1.1d. Cathode diffusion layer

[0036] The cathode diffusion layer 14 can be made of a porous material with electrical conductivity, for example. More specific examples include carbon porous materials (carbon paper, carbon cloth, glassy carbon, etc.) and metal porous materials (metal mesh, foamed metal).

[0037] MPL (microporous layer) can also be provided in the cathode diffusion layer as needed. MPL is a thin film coated on the side of the cathode catalyst layer 13 in the cathode diffusion layer 14. MPL has the function of adjusting moisture content by being hydrophobic or hydrophilic as needed. MPL is typically composed of hydrophobic resins such as polytetrafluoroethylene (PTFE) and conductive materials such as carbon black.

[0038] 1.1e. Anode diffusion layer

[0039] The anode diffusion layer 17 can be made of a porous material with electrical conductivity, for example. More specific examples include carbon porous materials (carbon paper, carbon cloth, glassy carbon, etc.) and metal porous materials (metal mesh, foamed metal).

[0040] 1.1f. Cathode diaphragm

[0041] The cathode diaphragm 15 is a component that supplies the reactive gas (air in this embodiment) to the cathode diffusion layer 14. It has multiple grooves 15a on its surface opposite the cathode diffusion layer 14, which function as flow paths for the reactive gas. 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; for example, a plate-like component can be formed into a wavy shape, as in this embodiment. In this case, the plate thickness is typically 0.1 mm to 0.2 mm, and the height of the unevenness is typically around 0.5 mm.

[0042] In the case of a wavy shape, a cathode diaphragm 15 is spaced between adjacent grooves 15a, and a groove 15b is formed on the opposite side, which functions as a cooling water flow path.

[0043] In addition, according to Figure 1 It can be seen that an air inlet hole A is provided on the cathode diaphragm 15 at the position where it extends from the power generation section 11 to become the outer side, at one end of the groove 15a and groove 15b. 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 grooves 15a and 15b. out Cooling water outlet hole W out Hydrogen inlet hole H in Here, slot 15a is connected to air inlet hole A. in Air outlet hole A out Connecting slot 15b with cooling water inlet hole W in Cooling water outlet hole Wout Connected.

[0044] The material constituting the cathode diaphragm 15 can be any material suitable for use as a diaphragm in a fuel cell cell, or it can be an impermeable conductive material. Examples of such materials include compressed carbon that is impermeable and dense, and stamped metal sheets.

[0045] 1.1g. Anode diaphragm

[0046] The anode diaphragm 18 is a component that supplies the reactant gas (hydrogen) to the anode diffusion layer 17. It has multiple grooves 18a on the surface opposite the anode diffusion layer 17, which function as flow paths for the reactant gas. The shape of the grooves is not particularly limited as long as the reactant gas can be appropriately supplied to the anode diffusion layer 17; for example, a plate-like component can be formed into a wavy shape, as in this embodiment. In this case, the plate thickness is typically 0.1 mm to 0.2 mm, and the height of the unevenness is typically around 0.4 mm.

[0047] In the case of a wavy shape, in this configuration, an anode diaphragm 18 is spaced between adjacent grooves 18a, while grooves 18b are formed on opposite sides, which function as cooling water flow paths.

[0048] In addition, according to Figure 1 It can be seen that an air inlet hole A is provided on the anode diaphragm 18 at the position where it extends from the power generation section 11 to become the outer side, at one end of the groove 18a and groove 18b. 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 grooves 18a and 18b. out Cooling water outlet hole W out Hydrogen inlet hole H in Here, tank 18a is connected to hydrogen inlet hole H. in Hydrogen outlet hole H out Connecting slot 18b with cooling water inlet hole W in Cooling water outlet hole W out Connected.

[0049] The material constituting the anode membrane 18 can be any material suitable for use as a membrane in a fuel cell cell, or it can be an impermeable conductive material. Examples of such materials include compressed carbon that is impermeable and dense, and stamped metal sheets.

[0050] 1.1h. Power generation carried out by the power generation department.

[0051] As is well known, the fuel cell 10 described above generates electricity as follows.

[0052] If hydrogen is supplied from the tank 18a of the anode diaphragm 18, the hydrogen is decomposed into protons (H+) in the anode catalyst layer 16 through the anode diffusion layer 17. + ) and electrons (e - Protons pass through the electrolyte membrane 12, and electrons pass through conductive wires connected to the outside, reaching the cathode catalyst layer 13 respectively. Here, oxygen (air) is supplied to the cathode catalyst layer 13 from the tank 15a of the cathode diaphragm 15 via the cathode diffusion layer 14. In the cathode catalyst layer 13, water (H2O) is generated from protons, electrons, and oxygen. The generated water passes through the cathode diffusion layer 14, reaches the tank 15a of the cathode diaphragm 15, and is discharged.

[0053] That is, in the fuel cell cell 10, the flow of electrons from the anode catalyst layer 16 through conductive wires connected to the outside is used as current.

[0054] 1.2.Peripheral part

[0055] Peripheral part 21 is Figure 2 The outer side of the power generation section 11, surrounded by dotted lines, is the outer periphery of the fuel cell cell 10. This part does not contribute to power generation but is responsible for supplying various fluids to the power generation section, collecting fluids from the power generation section, and sealing the area. The outer periphery 21 is located in... Figure 4 The diagram shows the layered structure (BB section) of the outer peripheral portion 21, in which multiple layers are stacked. Specifically, in this embodiment, the outer peripheral portion 21 has the following structure.

[0056] A resin sheet 23 is disposed between the cathode diaphragm 15 and the anode diaphragm 18 in the outer peripheral portion 21, and the resin sheet 23 is used to seal the interior of the fuel cell cell 10. Figure 1 It can be seen that the resin sheet 23 is configured to surround the membrane electrode assembly.

[0057] The resin sheet 23 functions as a sealing component that seals the cathode diaphragm 15 and the anode diaphragm 18 between the outer periphery 21 of the fuel cell cell 10.

[0058] The resin sheet 23 includes a substrate 24, an adhesive layer 25 disposed on one side of the substrate 24 (the side facing the cathode diaphragm), and an adhesive layer 26 disposed on the other side of the substrate 24 (the side facing the anode diaphragm). The adhesive layer 25 is bonded to the cathode diaphragm 15, and the adhesive layer 26 is bonded to the anode diaphragm 18, thereby sealing the power generation unit 11 internally.

[0059] The substrate 24 is formed of a thermoplastic resin material with electrical insulation, airtightness, and a high melting point. Examples of such materials include polyethylene naphthalate, polyphenylene ether, and polyphenylene sulfide. The thickness of the substrate 24 is not particularly limited, but is between 0.05 mm and 0.25 mm. The adhesive layers 25 and 26 are composed of adhesives and binders.

[0060] Furthermore, on the outer periphery 21, protrusions, i.e., ribs 30 and 31, protruding in the z-direction are respectively provided on the cathode diaphragm 15 and the anode diaphragm 18. The shape of the ribs 30 and 31 is not particularly limited as long as they are protrusions. For example, as described above, when the cathode diaphragm 15 and the anode diaphragm 18 are formed by making the plate wavy, the ribs 30 and 31 can also be protrusions based on the concave and convex portions of the grooves 15a and 18a.

[0061] In this disclosure, on the side of ribs 30 and 31 opposite to the side where the resin sheet 23 is disposed, that is, the side facing the adjacent fuel cell 10 when multiple fuel cell cells 10 are overlapped to form a fuel cell stack, ribs 30 and 31 have engaging portions 30a and 31a. In this embodiment, engaging portions 30a and 31a are engaging protrusions protruding in the z-direction.

[0062] The engaging parts 30a and 31a are configured such that, when viewed from above (from the z-direction, from the z-direction), the engagement parts 30a and 31a are positioned such that, when viewed from above (from ... Figure 4 The position of the apex of arrow C (observed from different angles) is different. Therefore, as will be described later, when adjacent fuel cell cells 10 move relatively in the y direction, the engaging part 30a and engaging part 31a can engage with each other via the cell seal 40 to suppress positional displacement in the y direction.

[0063] The shapes of the engaging portions 30a and 31a are not particularly limited; when they are protrusions, they can be quadrilaterals, triangles, other polygons, semicircles, semi-ellipses, etc. In this embodiment, the engaging portions 30a and 31a are trapezoidal in shape, with their engaging surfaces inclined relative to the y-direction as inclined surfaces 30b and 31b. The offset relative to the y-direction through these inclined surfaces 30b and 31b easily generates a reaction force.

[0064] Figure 5 Examples of ribs 30 and 31 having their tops entirely consisting of engaging parts 30a and 30b, and having inclined surfaces.

[0065] On the outer periphery 21, an inter-cell seal 40 is also stacked on a diaphragm (cathode diaphragm 15 in this embodiment) of the fuel cell 10. Thus, the inter-cell seal 40 is stacked in such a way that it contacts the top of the rib 30, particularly the engaging portion 30a.

[0066] Therefore, the cell-to-cell seal 40 is as follows: Figure 1 , Figure 2 (exist Figure 2 (Indicated by shading in the image) A frame-shaped sheet component arranged along the outer periphery 21. Since the cell-to-cell seal 40 preferably has both sealing properties and flexibility, it is preferably made of an elastomer. The specific material of the elastomer is not particularly limited, and examples include ethylene propylene rubber, fluoropolymer rubber, and silicone rubber.

[0067] As will be described later, when multiple fuel cell cells 10 are stacked in a fuel cell stack, deviations caused by dimensional tolerances and stacking tolerances can easily occur during the contact between the membranes, sometimes making it impossible to achieve the desired meshing between the ribs. In contrast, by using the cell-to-cell seal 40, the cell-to-cell meshing can be achieved more effectively by absorbing dimensional tolerances and stacking tolerances, thereby suppressing relative movement of the fuel cell cells.

[0068] 2. Fuel cell stack

[0069] 2.1. Overall Structure

[0070] The fuel cell stack 50 is a component formed by stacking multiple (approximately 50 to 400) of the aforementioned fuel cell cells 10, and collects power from the multiple fuel cell cells 10. Figure 6 The diagram shows an outline of its structure. The fuel cell stack 50 includes a battery pack housing 51, an end plate 52, multiple fuel cell cells 10, a current collector 54, and a force-applying component 55.

[0071] The battery pack housing 51 is a housing that houses the multiple overlapping fuel cell cells 10, current collectors 54, and force-applying components 55 inside. In this embodiment, the battery pack housing 51 is a quadrilateral cylindrical shape with one end open and the other end closed, and plate-like sheets extend along the edge of the opening to the side opposite to the opening to form a flange 51a.

[0072] End plate 52 is a plate-shaped component that blocks the opening of battery pack housing 51. End plate 52 is fixed to battery pack housing 51 by means of bolts and nuts, etc., to cover the overlapping part of flange 51a of battery pack housing 51.

[0073] The fuel cell 10 is as described above. Multiple such fuel cell cells 10 are stacked. In this case, the anode membrane 18 of adjacent fuel cell cells 10 is arranged to overlap with the cathode membrane 15 of one fuel cell cell 10. Furthermore, a cooling water flow path is formed by the overlap of the grooves 15b of the cathode membrane 15 and the grooves 18b of the anode membrane 18.

[0074] The current collector 54 is a component that collects electricity from the stacked fuel cell cells 10. Therefore, the current collector 54 is disposed at one end and the other end of the stacked structure of the fuel cell cells 10 in the stacking direction, with one end being the positive electrode and the other the negative electrode. It is configured to connect to terminals (not shown) on the current collector 54 so as to enable external electrical connection.

[0075] The force-applying member 55 is housed inside the battery pack housing 51 and applies pressure to the stacked structure of the fuel cell cell 10 in its stacking direction. For example, a disc spring can be used as the force-applying member.

[0076] 2.2. Layered structure in the outer periphery

[0077] Figure 7 This indicates the stacked structure of the fuel cell stack 50 focusing on the outer periphery 21 of the fuel cell cell 10. Figure 7 by Figure 4 The view shows the fuel cell 10, indicating that the fuel cell 10 is stacked (in... Figure 7 The middle part shows two adjacent fuel cell cells (10).

[0078] according to Figure 7 It can be seen that in the outer periphery 21 of the fuel cell cells 10 stacked by the fuel cell stack 50, adjacent fuel cell cells 10 are stacked with inter-cell seals 40 sandwiched between them. At this time, the engaging portion 30a of the rib 30 of one adjacent fuel cell cell 10 and the engaging portion 31a of the rib 31 of the other fuel cell cell 10 bite into the inter-cell seal 40 from opposite sides. When viewed from the y-direction, the ribs 30 and 31 are arranged at a partially overlapping position. Thus, the opposing ribs 30 and 31 can engage with adjacent fuel cell cells 10 via the inter-cell seal 40. For example, see... Figure 7 To illustrate, when the fuel cell cell 10 on the upper side of the paper moves in the direction of arrow D, Figure 7 In the area surrounded by the dotted ellipse, the engaging portion 31a of the rib 31 moves in the same direction as arrow D, and engages with the engaging portion 30a of the rib 30 of the fuel cell cell 10 on the lower side of the paper via the cell seal 40, thus preventing further movement of the fuel cell cell 10 on the upper side of the paper.

[0079] Therefore, according to this method, in addition to the movement suppression caused by the frictional force between the fuel cell cells and the cell-to-cell seal, the movement is also hindered by the aforementioned meshing structure, so even when a stronger force is applied to the fuel cell cells, the generation of fuel cell cell displacement can be suppressed.

[0080] In addition, Figure 7 The area shown is effective for movement in the direction indicated by arrow D, but not for movement in the opposite direction or other directions. Figure 7 Other parts, not shown, generate this engagement in the direction of movement, thereby appropriately suppressing the deflection of the fuel cell.

[0081] At this time, the opposing engaging parts 30a and 31a engage at the inclined surfaces 30b and 31b, thereby easily generating a reaction force relative to the direction of movement, thus more effectively suppressing the occurrence of the offset.

[0082] In addition, when multiple fuel cell cells 10 are stacked in a fuel cell stack, misalignment caused by dimensional tolerances and stacking tolerances can easily occur during the contact between the membranes. By using the cell-to-cell seal 40 in this clamping manner, the cell-to-cell seal 40 can absorb dimensional tolerances and stacking tolerances and more effectively suppress the relative movement between the cells.

Claims

1. A fuel cell stack, comprising at least a plurality of fuel cell cells and an inter-cell seal sandwiched between the plurality of fuel cell cells, characterized in that, The plurality of fuel cell cells have ribs that contact the seals between the cells. The ribs are the interlocking shapes of adjacent fuel cell cells separated by a cell-to-cell seal.

2. The fuel cell stack according to claim 1, characterized in that, The rib has an inclined surface, and the opposing rib is configured to engage on the inclined surface.

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