Water electrolysis cell stack and manufacturing method thereof

Abstract

To provide a water electrolysis cell stack, whose pressure resistance can be enhanced.SOLUTION: The water electrolysis cell stack is constituted of a plurality of water electrolysis cells overlaid one after another, with the plurality of water electrolysis cells neighboring each other, the electrolysis cells each comprising an anode separator and a cathode separator respectively, the anode separators and the cathode separators each comprising grooves on the front surface and back surface thereof, functioning as a flow channel, in which a resin is disposed at least in a portion of a gap between the neighboring water electrolysis cells, in the area where the grooves are formed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a water electrolysis cell stack and a method for manufacturing the same. [Background technology]

[0002] Various studies have been conducted on water electrolysis devices. For example, Patent Document 1 discloses a water electrolysis cell stack in which water electrolysis cells each having a separator on the hydrogen electrode side and the oxygen electrode side are stacked. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-089949 Summary of the Invention [Problem to be solved by the invention]

[0004] The water electrolysis cell stack described in Patent Document 1 has a configuration in which there are no gaps between the water electrolysis cells, which poses the problem of separator deformation due to the pressure of hydrogen generated by water electrolysis.

[0005] The present disclosure has been made in view of the above-described circumstances, and has as its main object to provide a water electrolysis cell stack that can improve pressure resistance, and a method for manufacturing the same. [Means for solving the problem]

[0006] The present disclosure provides a water electrolysis cell stack having the following features: A water electrolysis cell stack in which a plurality of water electrolysis cells are stacked, the plurality of water electrolysis cells are adjacent to one another, the water electrolysis cell has an anode separator and a cathode separator; the anode separator and the cathode separator have grooves on the front and back surfaces that serve as flow paths; A resin is disposed in at least a part of the gap between the adjacent water electrolysis cells in the region where the groove is formed.

[0007] In the water electrolysis cell stack of the present disclosure, the filling rate of the resin in the gap may be 30% or more.

[0008] In the water electrolysis cell stack of the present disclosure, the resin may be at least one selected from the group consisting of polyethylene, polystyrene, acrylonitrile butadiene styrene resin, polypropylene, polycarbonate, polyethersulfone, polyether ether ketone, modified polyphenylene ether, acrylonitrile ethylene propylene diene styrene resin, polyamide, and polyimide.

[0009] The present disclosure provides a method for manufacturing a water electrolysis cell stack having the following features. In a method for manufacturing a water electrolysis cell stack, the resin is filled into the gap by injection molding. [Effects of the Invention]

[0010] The water electrolysis cell stack of the present disclosure can improve pressure resistance. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional schematic diagram illustrating an example of a water electrolysis cell stack according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Embodiments of the present disclosure are described below. It should be noted that matters necessary for implementing the present disclosure other than those specifically mentioned in this specification (e.g., the general configuration and manufacturing process of a water electrolysis cell stack that do not characterize the present disclosure) can be understood as design matters for a person skilled in the art based on prior art in the relevant field. The present disclosure can be implemented based on the contents disclosed in this specification and common general technical knowledge in the relevant field. Furthermore, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships. In this specification, the use of "to" to indicate a range of values ​​means that the values ​​before and after it are included as the lower and upper limits. Any combination of upper and lower limits in the numerical range can be adopted.

[0013] The present disclosure provides a water electrolysis cell stack having the following features: A water electrolysis cell stack in which a plurality of water electrolysis cells are stacked, the plurality of water electrolysis cells are adjacent to one another, the water electrolysis cell has an anode separator and a cathode separator; the anode separator and the cathode separator have grooves on the front and back surfaces that serve as flow paths; A resin is disposed in at least a part of the gap between the adjacent water electrolysis cells in the region where the groove is formed.

[0014] Generally, water electrolysis cell stacks pressurize the hydrogen generated by water electrolysis, so they need to have higher pressure resistance than fuel cell stacks. The maximum internal pressure of a water electrolysis cell stack is about 3 MPa, while that of a fuel cell stack is about 0.3 MPa. However, it is difficult to directly convert separators for fuel cells into separators for water electrolysis cells. Furthermore, water electrolysis cells also use the water supplied for water electrolysis as a coolant, and in many cases do not require the coolant flow paths that are required for single fuel cell cells.

[0015] In this disclosure, a fuel cell stack having an oxidant gas flow path, a fuel gas flow path, and a coolant flow path is applied to a water electrolysis cell stack. In this disclosure, the coolant flow path is filled with resin to prevent the separator from being deformed or damaged by the pressure of the gas flowing through the fuel gas flow path and the coolant flow path. According to this disclosure, even if the separator has grooves that serve as flow paths on the front and back sides formed by press molding, the pressure resistance of the water electrolysis cell stack can be improved by filling the gaps between adjacent water electrolysis cells with resin. In this disclosure, applying a fuel cell stack to a water electrolysis cell stack can improve the production efficiency of the water electrolysis cell stack.

[0016] The water electrolysis cell of the present disclosure electrolyzes water supplied to the anode (oxygen electrode), generating oxygen from the anode and hydrogen from the cathode (hydrogen electrode) as follows. Anode: H2O → 2H + + 1 / 2O2+ 2e - Cathode: 2H + + 2e - → H2 In the water electrolysis cell of the present disclosure, the pressure of the hydrogen electrode in the water electrolysis cell may be higher than the pressure of the oxygen electrode.

[0017] The water electrolysis cell stack according to the present disclosure is a stack of multiple water electrolysis cells. The water electrolysis cells are adjacent to each other. The number of water electrolysis cells stacked is not particularly limited, and may be, for example, from 2 to several hundred.

[0018] The water electrolysis cell may include a membrane electrode assembly (MEA). The membrane electrode assembly includes an anode, an electrolyte membrane, and a cathode in this order. The anode (oxygen electrode) in the present disclosure includes an anode catalyst layer, and may include an anode-side gas diffusion layer as needed. The cathode (hydrogen electrode) in the present disclosure includes a cathode catalyst layer, and may include a cathode-side gas diffusion layer as needed. The anode gas diffusion layer, anode catalyst layer, electrolyte membrane, cathode catalyst layer, and cathode gas diffusion layer are collectively referred to as a membrane electrode gas diffusion layer assembly (MEGA).

[0019] The cathode catalyst layer and the anode catalyst layer are collectively referred to as catalyst layers. The catalyst layer may include, for example, a catalytic metal that promotes water electrolysis, a proton-conductive electrolyte, and an electron-conductive carrier. Examples of catalyst metals that can be used include iridium (Ir), iridium dioxide (IrO2), ruthenium (Ru), platinum (Pt), and alloys of Pt with other metals (e.g., Pt alloys mixed with cobalt and nickel). The anode catalyst layer may use, for example, Ir, IrO2, and Ru as the catalyst metal, and the cathode catalyst layer may use, for example, Pt and Pt alloys as the catalyst metal. The electrolyte may be a fluorine-based resin, etc. As the fluorine-based resin, for example, a Nafion solution may be used. The catalytic metal is supported on a carrier, and in each catalyst layer, the carrier supporting the catalytic metal (catalyst-supported carrier) and the electrolyte may be mixed together. Examples of the carrier for supporting the catalytic metal include carbon materials such as carbon, which are generally available commercially.

[0020] The electrolyte membrane may be a solid polymer electrolyte membrane. Examples of the solid polymer electrolyte membrane include a fluorine-based electrolyte membrane such as a thin film of perfluorosulfonic acid containing water, and a hydrocarbon-based electrolyte membrane. The electrolyte membrane may be, for example, a Nafion membrane (manufactured by DuPont).

[0021] The anode side gas diffusion layer and the cathode side gas diffusion layer are collectively referred to as gas diffusion layers. The gas diffusion layer may be a gas-permeable, i.e., porous, electrically conductive member or the like. Examples of conductive members include porous carbon materials such as carbon cloth and carbon paper, and porous metal members such as 3D fine mesh, metal mesh, and foam metal. The gas diffusion layer may have pores of 1 to several hundred μm.

[0022] The water electrolysis cell has an anode separator and a cathode separator. The anode separator and the cathode separator have grooves on the front and back surfaces to serve as flow paths. The anode separator and the cathode separator are collectively referred to as the separator. The separator may have flow paths for reaction fluids such as reaction water, oxygen, hydrogen, etc. on the surface in contact with the gas diffusion layer. The separator may also have flow paths for a cooling medium for maintaining a constant temperature of the water electrolysis cell on the surface opposite to the surface in contact with the gas diffusion layer. The anode separator may have a flow path for anode fluid such as reaction water, oxygen, etc. on the surface in contact with the anode-side gas diffusion layer. The anode separator may also have a flow path for a cooling medium for maintaining a constant temperature of the water electrolysis cell on the surface opposite to the surface in contact with the anode-side gas diffusion layer. The cathode separator may have a flow path for a cathode fluid such as hydrogen on the surface in contact with the cathode-side gas diffusion layer, and may have a flow path for a cooling medium for maintaining a constant temperature of the water electrolysis cell on the surface opposite to the surface in contact with the cathode-side gas diffusion layer. The separator may have holes serving as manifolds, such as supply holes and discharge holes, for circulating fluids such as reaction water, oxygen, hydrogen, and a cooling medium in the stacking direction of the water electrolysis cells. Water or the like can be used as the reaction water and the cooling medium. The supply holes include an anode supply hole, a cathode supply hole, and a coolant supply hole. Examples of the exhaust holes include an anode exhaust hole, a cathode exhaust hole, and a coolant exhaust hole. The separator may be a gas-impermeable conductive material, etc. Examples of the gas-impermeable conductive material include dense carbon made gas-impermeable by compressing a resin material such as a thermosetting resin, a thermoplastic resin, or a resin fiber, and a carbon material such as a carbon powder or a carbon fiber, and a press-molded metal (e.g., titanium, stainless steel, etc.) plate. The shape of the separator may be rectangular, horizontally elongated hexagonal, horizontally elongated octagonal, circular, oval, or the like.

[0023] The water electrolysis cell may have a frame with an opening. The opening in the frame may be located in the center of the frame. The opening in the frame accommodates a membrane electrode assembly or a membrane electrode gas diffusion layer assembly. The frame may have holes serving as manifolds in areas other than the end portions and openings in the planar direction in a plan view. The holes in the frame are the same as the holes in the separator. The frame may be a structural member having adhesive, gas-tight, and insulating properties. The frame material may be, for example, a thermoplastic resin such as a polyester or modified olefin resin, or a thermosetting resin such as a modified epoxy resin. The frame material may also be a rubber material having elastic properties, such as EPDM (ethylene propylene diene rubber), fluorine-based rubber, or silicone rubber. The thickness of the frame may be 5 μm or more, or 20 μm or more, from the viewpoint of ensuring insulation, and may be 200 μm or less, or 150 μm or less, from the viewpoint of reducing the thickness of the water electrolysis cell.

[0024] The water electrolysis cell stack may have manifolds such as an inlet manifold to which the supply holes communicate and an outlet manifold to which the discharge holes communicate. Examples of the inlet manifold include an anode inlet manifold, a cathode inlet manifold, and a coolant inlet manifold. Examples of the outlet manifold include an anode outlet manifold, a cathode outlet manifold, and a coolant outlet manifold. The coolant inlet manifold and the coolant outlet manifold are collectively referred to as the coolant manifold.

[0025] In the water electrolysis cell stack of the present disclosure, a resin is disposed in at least a portion of the gap between adjacent water electrolysis cells in a region where the separator grooves are formed. The region where the resin is disposed may be at least a portion or the entire region where the separator coolant flow channels are formed between adjacent water electrolysis cells. Alternatively, the resin may be disposed in the entire coolant manifold of the water electrolysis cell stack. The filling rate of the resin in the gaps between adjacent water electrolysis cells may be 30% or more. The resin may be at least one selected from the group consisting of polyethylene, polystyrene, acrylonitrile butadiene styrene (ABS) resin, polypropylene, polycarbonate, polyethersulfone, polyetheretherketone, modified polyphenylene ether, acrylonitrile ethylene propylene diene styrene (AES) resin, polyamide, and polyimide.

[0026] In the method for manufacturing a water electrolysis cell stack according to the present disclosure, the gaps between adjacent water electrolysis cells may be filled with a resin by injection molding. The injection molding may be foam injection molding. Foam injection molding allows the filling rate of the resin in the gaps between adjacent water electrolysis cells to be controlled, thereby reducing the weight of the water electrolysis cell stack. The resin used for foam injection molding may be, among the above resins, particularly modified polyphenylene ether, polypropylene, polycarbonate, acrylonitrile ethylene propylene diene styrene (AES) resin, polyamide, or the like. The resin may be injected through a coolant manifold of the water electrolysis cell stack by injection molding after the water electrolysis cells are stacked to produce a water electrolysis cell stack, thereby improving the production efficiency of water electrolysis cell stacks.

[0027] FIG. 1 is a cross-sectional schematic diagram showing an example of a water electrolysis cell stack according to the present disclosure. As shown in FIG. 1 , the water electrolysis cell stack 100 of the present disclosure is a stack of multiple water electrolysis cells 50. The water electrolysis cell 50 includes an anode separator 10, a membrane electrode assembly (MEA) 11, and a cathode separator 12. A coolant flow path 20 is provided on each of the anode separator 10 and the cathode separator 12, on the side opposite the membrane electrode assembly 11. An anode fluid flow path 30 is provided on the surface of the anode separator 10 facing the membrane electrode assembly 11. A cathode fluid flow path 40 is provided on the surface of the cathode separator 12 facing the membrane electrode assembly 11. A resin 21 is disposed in the gaps between adjacent water electrolysis cells 50 in the region of the coolant flow path 20. Filling the gaps between adjacent water electrolysis cells 50 with the resin 21 improves the pressure resistance of the water electrolysis cell stack 100. [Explanation of symbols]

[0028] 10 Anode separator 11 Membrane electrode assembly (MEA) 12 Cathode separator 20 Coolant flow path 21 Resin 30 Anode fluid flow path 40 cathode fluid flow path 50 water electrolysis cell 100 Water electrolysis cell stack

Claims

1. A water electrolysis cell stack in which a plurality of water electrolysis cells are stacked, the plurality of water electrolysis cells are adjacent to one another, the water electrolysis cell has an anode separator and a cathode separator; the anode separator and the cathode separator have grooves on the front and back surfaces that serve as flow paths; a resin disposed in at least a portion of the gap between the adjacent water electrolysis cells in the region where the groove is formed.

2. The water electrolysis cell stack according to claim 1 , wherein a filling rate of the resin in the gap is 30% or more.

3. 2. The water electrolysis cell stack according to claim 1, wherein the resin is at least one selected from the group consisting of polyethylene, polystyrene, acrylonitrile butadiene styrene resin, polypropylene, polycarbonate, polyethersulfone, polyether ether ketone, modified polyphenylene ether, acrylonitrile ethylene propylene diene styrene resin, polyamide, and polyimide.

4. A method for manufacturing a water electrolysis cell stack according to claim 1, comprising: and filling the gap with the resin by injection molding.

5. The water electrolysis cell has a membrane electrode assembly, a flow path for an anode fluid is provided on a surface of the anode separator facing the membrane electrode assembly, a cathode fluid flow path is provided on a surface of the cathode separator facing the membrane electrode assembly, the anode fluid is reacted water and oxygen; The water electrolysis cell stack of claim 1 , wherein the cathode fluid is hydrogen.

6. A method for manufacturing a water electrolysis cell stack as described in claim 4, wherein the injection molding is foam injection molding.

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