Water electrolysis steril

Abstract

To provide a water electrolysis cell whose pressure resistance can be enhanced.SOLUTION: The water electrolysis cell has an anode-side porous flow path, a membrane / electrode joint body, and a cathode-side porous flow path in this order. The water electrolysis cell has a separator disposed at least either on the opposite side of the membrane / electrode joint body in the anode-side porous flow path or on the opposite side of the membrane / electrode joint body in the cathode side porous flow path. The membrane / electrode joint body has an anode catalyst layer, an electrolyte membrane, and a cathode catalyst layer in this order from the anode-side porous flow path. An area in a surface direction of the anode-side porous flow path is larger than an area in a surface direction of the cathode-side porous flow path in a plan view.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a water electrolysis cell. [Background technology]

[0002] Various studies have been conducted on water electrolysis devices. For example, Patent Document 1 discloses a technology in which the oxygen-side current collector is made larger than the hydrogen-side current collector, so that even if positive pressure is applied from the hydrogen-side current collector to the oxygen-side current collector, the pressure can be absorbed entirely by the surface of the oxygen-side current collector via the solid polymer electrolyte membrane. Patent Document 2 discloses a technique in which an electrolyte membrane is sandwiched between an anode current collector made of a porous conductor and a cathode current collector made of a porous conductor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-117140 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-210646 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 does not describe any pressure-resistant means for the members arranged outside the current collector, and there is a problem that if the current collector cannot be supported by the members arranged outside the current collector, there is a risk of the current collector being deformed.

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

[0006] The present disclosure provides a water electrolysis cell, comprising: the water electrolysis cell includes, in this order, an anode-side porous flow path, a membrane electrode assembly, and a cathode-side porous flow path; the water electrolysis cell has a separator on at least one of a side of the anode-side porous flow channel opposite to the membrane electrode assembly side and a side of the cathode-side porous flow channel opposite to the membrane electrode assembly side, the membrane electrode assembly has, from the anode-side porous flow path side, an anode catalyst layer, an electrolyte membrane, and a cathode catalyst layer, The water electrolysis cell is provided, wherein the area of ​​the anode-side porous flow channel in the planar direction is larger than the area of ​​the cathode-side porous flow channel in the planar direction in a plan view.

[0007] In the water electrolysis cell according to the present disclosure, the water electrolysis cell has an anode-side supply hole, a cathode-side supply hole, an anode-side discharge hole, and a cathode-side discharge hole at an end portion in a planar direction and in a region where the membrane electrode assembly is not present, in a plan view; the anode-side porous flow path connects the anode-side supply hole and the anode-side discharge hole; The cathode porous flow path may connect the cathode supply hole and the cathode discharge hole.

[0008] In the water electrolysis cell of the present disclosure, the anode-side porous flow channel and the cathode-side porous flow channel may each be made of a metal porous member.

[0009] In the water electrolysis cell according to the present disclosure, an anode-side gas diffusion layer is disposed between the anode-side porous flow path and the anode catalyst layer; a surface area of ​​the anode-side porous flow channel in a planar direction is larger than a surface area of ​​the anode-side gas diffusion layer in a planar direction; a cathode-side gas diffusion layer is disposed between the cathode-side porous flow path and the cathode catalyst layer; the cathode-side porous flow channel has a surface area smaller than the surface area of ​​the cathode-side gas diffusion layer; The area of ​​the anode-side gas diffusion layer in the plane direction may be larger than the area of ​​the cathode-side gas diffusion layer in the plane direction, and the edge of the anode-side gas diffusion layer may be located outward from the edge of the cathode-side gas diffusion layer over its entire periphery in a plan view.

[0010] In the water electrolysis cell of the present disclosure, the water electrolysis cell comprises a first frame having a first opening for accommodating the anode-side porous flow path, a second frame having a second opening for accommodating the membrane electrode assembly, and a third frame having a third opening for accommodating the cathode-side porous flow path, the first frame has a first anode side supply hole, a first cathode side supply hole, a first anode side discharge hole, and a first cathode side discharge hole at an end in a planar direction and in a region where the membrane electrode assembly is not present, in a plan view; the second frame has a second anode side supply hole, a second cathode side supply hole, a second anode side discharge hole, and a second cathode side discharge hole at an end in a planar direction and in a region where the membrane electrode assembly is not present, in a plan view, the third frame has a third anode side supply hole, a third cathode side supply hole, a third anode side discharge hole, and a third cathode side discharge hole at an end in a planar direction and in a region where the membrane electrode assembly is not present, in a plan view, the anode-side porous flow path connects the first anode-side supply hole and the first anode-side discharge hole of the first frame in a plan view; The cathode porous flow path may connect the third cathode supply hole and the third cathode discharge hole of the third frame in a plan view. [Effects of the Invention]

[0011] The water electrolysis cell of the present disclosure can have improved pressure resistance. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective schematic diagram illustrating an example of a water electrolysis cell according to the present disclosure. [Figure 2]FIG. 2 is a cross-sectional view schematically illustrating the water electrolysis cell shown in FIG. 1 along the line AA. [Figure 3] FIG. 2 is a schematic plan view illustrating an example of some of the constituent members of the water electrolysis cell of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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 that do not characterize the present disclosure) can be understood as design matters of 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.

[0014] The present disclosure provides a water electrolysis cell, comprising: the water electrolysis cell includes, in this order, an anode-side porous flow path, a membrane electrode assembly, and a cathode-side porous flow path; the water electrolysis cell has a separator on at least one of a side of the anode-side porous flow channel opposite to the membrane electrode assembly side and a side of the cathode-side porous flow channel opposite to the membrane electrode assembly side, the membrane electrode assembly has, from the anode-side porous flow path side, an anode catalyst layer, an electrolyte membrane, and a cathode catalyst layer, The water electrolysis cell is provided, wherein the area of ​​the anode-side porous flow channel in the planar direction is larger than the area of ​​the cathode-side porous flow channel in the planar direction in a plan view.

[0015] When designing a water electrolysis cell structure to withstand pressure, if a material that is prone to gaps due to its press-molded structure, such as a metal separator, is used, the separator will deform due to the pressure difference between the hydrogen electrode and the oxygen electrode, and the total pressure applied to the water electrolysis cell, making it difficult to ensure pressure resistance. If a gap exists when the above-mentioned pressure difference occurs, the low-pressure side component that is pushed from the high-pressure side without a supporting support will be damaged by local bending stress and elongation stress due to the pressure, causing a gas leak. In other words, because the gap generates stress when a pressure difference occurs from the high-pressure side to the low-pressure side, it is desirable to have a structure that eliminates gaps as much as possible. Furthermore, because space occurs in the areas of the fluid inlet and fluid outlet portions adjacent to the holes that form the manifold, it is desirable to have a structure that does not create large gaps.

[0016] In the water electrolysis cell disclosed herein, porous (including 3D fine mesh) flow paths are disposed on the hydrogen electrode side and the oxygen electrode side, and the porous flow paths are formed in a region from the fluid inlet through the membrane electrode assembly to the fluid outlet in a plan view. By forming the porous flow paths in the regions of the fluid inlet and fluid outlet, it is possible to prevent the generation of spaces in the regions of the fluid inlet and fluid outlet. This minimizes gaps generated within the structure of the water electrolysis cell, and improves the pressure resistance of the water electrolysis cell to the total pressure applied thereto. Furthermore, in the water electrolysis cell disclosed herein, when the separator and frame are used to design a pressure-resistant structure, the components on the hydrogen electrode side, where the pressure is high, are made smaller, and the components on the oxygen electrode side, where the pressure is low, are made larger, thereby minimizing gaps between the components and reducing differential pressure stress occurring in the gaps. Since no gaps are provided on the oxygen electrode side, where the pressure is low, it is possible to prevent components from wedging into the gaps from the hydrogen electrode side, where the pressure is high, to the oxygen electrode side, where the pressure is low.

[0017] 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. The water electrolysis cell may be a water electrolysis cell stack, which is a stack of a plurality of such water electrolysis cells. 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 has, in this order, an anode-side porous flow path, a membrane electrode assembly (MEA), and a cathode-side porous flow path.

[0019] The membrane electrode assembly has an anode catalyst layer, an electrolyte membrane, and a cathode catalyst layer in this order.

[0020] The cathode (hydrogen electrode) in the present disclosure includes a cathode catalyst layer. The anode (oxygen electrode) in the present disclosure includes an anode catalyst layer.

[0021] 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.

[0022] The electrolyte membrane is sandwiched between two catalyst layers: one is a cathode catalyst layer and the other is an anode catalyst layer. 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).

[0023] The anode-side porous flow channel and the cathode-side porous flow channel are collectively referred to as the porous flow channel. The porous channel may be a gas permeable, ie, electrically conductive member having pores. 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 anode-side porous flow channel and the cathode-side porous flow channel may each be made of a metal porous member. The porous flow path may have pores ranging from 1 to several hundred μm. The porous flow passage may also function as a gas diffusion layer.

[0024] An anode-side gas diffusion layer may be disposed between the anode-side porous flow channel and the anode catalyst layer. A cathode-side gas diffusion layer may be disposed between the cathode-side porous flow channel and the cathode catalyst layer. 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 conductive material as exemplified in the porous flow channel. The anode-side gas diffusion layer, the membrane electrode assembly, and the cathode-side gas diffusion layer are collectively referred to as a membrane electrode gas diffusion layer assembly (MEGA).

[0025] The water electrolysis cell may include a first frame having a first opening for accommodating the anode-side porous flow path, a second frame having a second opening for accommodating the membrane electrode assembly or the membrane electrode-gas diffusion layer assembly, and a third frame having a third opening for accommodating the cathode-side porous flow path. The first frame, the second frame, and the third frame are collectively referred to as a frame. The opening in the frame may be located in the center of the frame. The first opening has a larger area in the planar direction than the third opening that houses the cathode-side porous flow channel in a plan view. The surface area of ​​the second opening may be the same as the surface area of ​​the first opening or the same as the surface area of ​​the third opening. The surface area of ​​the second opening may be smaller than the surface area of ​​the first opening and larger than the surface area of ​​the third opening in a plan view. The shape of the periphery of the second opening of the second frame may be a shape that fits the shape of the membrane electrode assembly or the membrane electrode gas diffusion layer assembly. When the shape of the membrane electrode assembly and the shape of the membrane electrode gas diffusion layer assembly are stepped, the shape of the periphery of the second opening may be stepped so that the stepped membrane electrode assembly or the stepped membrane electrode gas diffusion layer assembly fits. The second frame may also be a composite frame formed by stacking frames having openings corresponding to the shapes of the components constituting the membrane electrode assembly or the membrane electrode gas diffusion layer assembly. For example, when the second frame accommodates a membrane electrode gas diffusion layer assembly and the surface area of ​​the composite of the anode side gas diffusion layer and the membrane electrode assembly is larger than the surface area of ​​the cathode side gas diffusion layer, the second frame may be formed by stacking a fourth frame having a fourth opening corresponding to the shape of the composite and a fifth frame having a fifth opening corresponding to the shape of the cathode side gas diffusion layer.

[0026] The water electrolysis cell may have holes serving as manifolds, such as an anode-side supply hole, a cathode-side supply hole, an anode-side discharge hole, and a cathode-side discharge hole, at end portions in the planar direction and in regions where no membrane electrode assembly is present in a plan view. The frame may have manifold holes such as an anode supply hole, a cathode supply hole, an anode discharge hole, and a cathode discharge hole at its end in the planar direction in a region where no membrane electrode assembly is present in a plan view. That is, the first frame has a first anode supply hole, a first cathode supply hole, a first anode discharge hole, and a first cathode discharge hole at its end in the planar direction in a region where no membrane electrode assembly is present in a plan view. The second frame has a second anode supply hole, a second cathode supply hole, a second anode discharge hole, and a second cathode discharge hole at its end in the planar direction in a region where no membrane electrode assembly is present in a plan view. The third frame has a third anode supply hole, a third cathode supply hole, a third anode discharge hole, and a third cathode discharge hole at its end in the planar direction in a region where no membrane electrode assembly is present in a plan view. The anode-side supply holes, cathode-side supply holes, anode-side discharge holes, and cathode-side discharge holes of the first frame, the second frame, and the third frame may be aligned and arranged to communicate with each other. That is, the first anode-side supply hole, the second anode-side supply hole, and the third anode-side supply hole may be aligned and arranged to communicate with each other. The first anode-side discharge hole, the second anode-side discharge hole, and the third anode-side discharge hole may be aligned and arranged to communicate with each other. The first cathode-side supply hole, the second cathode-side supply hole, and the third cathode-side supply hole may be aligned and arranged to communicate with each other. The first cathode-side discharge hole, the second cathode-side discharge hole, and the third cathode-side discharge hole may be aligned and arranged to communicate with each other. The first anode-side supply hole, the first opening, and the first anode-side discharge hole of the first frame may communicate with each other in the planar direction in a plan view to form one communication hole. The third cathode supply hole, the third opening, and the third cathode discharge hole of the third frame may communicate with each other in the planar direction in a plan view to form one communication hole.

[0027] 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. The first frame, the second frame, and the third frame may be made of the same type of resin, or may be made of different types of resin. The first frame, the second frame, and the third frame may each have an adhesive function, and at least one of the first frame, the second frame, and the third frame may have an elastic function.

[0028] The anode-side porous flow path may connect the anode-side supply hole and the anode-side discharge hole. The cathode porous flow path may connect the cathode supply hole and the cathode discharge hole. Specifically, the anode-side porous flow path may connect the first anode-side supply hole and the first anode-side discharge hole of the first frame in a plan view. The cathode porous flow path may connect the third cathode supply hole and the third cathode discharge hole of the third frame in a plan view.

[0029] The water electrolysis cell has a separator on at least one of the side of the anode-side porous flow channel opposite to the membrane electrode assembly side and the side of the cathode-side porous flow channel opposite to the membrane electrode assembly side. The water electrolysis cell may have an anode separator on the side of the anode-side porous flow channel opposite to the membrane electrode assembly side, and a cathode separator on the side of the cathode-side porous flow channel opposite to the membrane electrode assembly side. The anode separator and the cathode separator are collectively referred to as the separator. 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 have flow paths for reaction fluids such as reaction water, oxygen, and hydrogen 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 separator may be a flat plate having no flow paths for reaction fluids or cooling medium. The anode separator may have a flow path for an anode fluid such as reaction water or oxygen on the surface in contact with the anode-side porous flow path. 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 porous flow path. The anode separator may be a flat plate having no flow path for the anode fluid or the cooling medium. The cathode separator may have a channel for a cathode fluid such as hydrogen on the surface in contact with the cathode-side porous channel. The cathode separator may also have a channel 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 porous channel. The cathode separator may be a flat plate that does not have a channel for a cathode fluid or a channel for a cooling medium. 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.

[0030] The surface area of ​​the oxygen electrode may be the same as or larger than the surface area of ​​the hydrogen electrode in a plan view. Specifically, the surface area of ​​the anode catalyst layer may be the same as or larger than the surface area of ​​the cathode catalyst layer in a plan view, and the edge of the anode catalyst layer may be located outside the edge of the cathode catalyst layer over the entire periphery in a plan view. The area of ​​the electrolyte membrane in the planar direction may be the same as the area of ​​the anode catalyst layer in the planar direction.

[0031] The area of ​​the anode-side porous flow channel in the planar direction is larger than the area of ​​the cathode-side porous flow channel in the planar direction in a plan view. The area in the plane direction of the region of the anode-side porous flow path that faces the membrane electrode assembly may be larger than the area in the plane direction of the region of the cathode-side porous flow path that faces the membrane electrode assembly in a plan view, and the edge of the region of the anode-side porous flow path that faces the membrane electrode assembly may be located outside the edge of the region of the cathode-side porous flow path that faces the membrane electrode assembly over the entire periphery. The surface area of ​​the region of the anode-side porous flow path that does not face the membrane electrode assembly may be the same as or larger than the surface area of ​​the region of the cathode-side porous flow path that does not face the membrane electrode assembly in a plan view. In the present disclosure, the region of the porous flow channel that does not face the membrane electrode assembly is the region from the hole that serves as the manifold of the water electrolysis cell to the membrane electrode assembly in a plan view, where the porous flow channel is located. The region of the porous flow channel that does not face the membrane electrode assembly is the region of the fluid inlet section or the region of the fluid outlet section. The fluid inlet section and the fluid outlet section are collectively referred to as the fluid outlet section. The region of the anode-side porous flow path that does not face the membrane electrode assembly is the region from the anode-side supply hole to the membrane electrode assembly in a plan view, where the anode-side porous flow path is located, i.e., the region of the fluid inlet, and the region from the anode-side discharge hole to the membrane electrode assembly in a plan view, where the anode-side porous flow path is located, i.e., the region of the fluid outlet. The region of the cathode-side porous flow path that does not face the membrane electrode assembly is the region from the cathode-side supply hole to the membrane electrode assembly in a plan view, where the cathode-side porous flow path is located, i.e., the region of the fluid inlet, and the region from the cathode-side discharge hole to the membrane electrode assembly in a plan view, where the cathode-side porous flow path is located, i.e., the region of the fluid outlet. The area of ​​the membrane electrode assembly in the planar direction may be larger than the area of ​​the cathode-side porous flow channel in the planar direction and smaller than the area of ​​the anode-side porous flow channel in the planar direction in a plan view. The region of the water electrolysis cell where the membrane electrode assembly is present may be pyramidal.

[0032] The area of ​​the anode-side porous flow channel in the planar direction may be larger than the area of ​​the anode-side gas diffusion layer in the planar direction. The area of ​​the cathode-side porous flow channel in the planar direction may be smaller than the area of ​​the cathode-side gas diffusion layer in the planar direction. The area of ​​the anode-side gas diffusion layer in the planar direction may be larger than the area of ​​the cathode-side gas diffusion layer in the planar direction, and the edge of the anode-side gas diffusion layer may be located outside the edge of the cathode-side gas diffusion layer over the entire periphery in a plan view. The area of ​​the anode-side gas diffusion layer in the planar direction may be the same as or larger than the area of ​​the anode catalyst layer in the planar direction, and the edge of the anode-side gas diffusion layer may be located outside the edge of the anode catalyst layer over the entire periphery in plan view. The surface area of ​​the cathode catalyst layer may be the same as the surface area of ​​the cathode-side gas diffusion layer, or may be larger than the surface area of ​​the cathode-side gas diffusion layer, and the edge of the cathode catalyst layer may be located outside the edge of the cathode-side gas diffusion layer over its entire periphery in a plan view.

[0033] FIG. 1 is a perspective schematic diagram illustrating an example of a water electrolysis cell according to the present disclosure. 1 , a water electrolysis cell 100 according to the present disclosure includes an anode-side porous flow path 10, a membrane electrode-gas diffusion layer assembly 20, a cathode-side porous flow path 30, and an anode separator 40. The water electrolysis cell 100 includes a first frame 11 having a first opening for accommodating the anode-side porous flow path 10, a second frame 21 having a second opening for accommodating the membrane electrode-gas diffusion layer assembly 20, and a third frame 31 having a third opening for accommodating the cathode-side porous flow path 30. The anode-side porous flow channel 10 and the cathode-side porous flow channel 30 are also arranged in the region of the fluid lead-out port 50, which is the region indicated by the chain circle in FIG.

[0034] Fig. 2 is a schematic cross-sectional view taken along line AA of the water electrolysis cell shown in Fig. 1. In Fig. 2, the same components as in Fig. 1 are denoted by the same reference numerals, and their description will be omitted. The membrane electrode gas diffusion layer assembly 20 has an anode side gas diffusion layer 22 , a membrane electrode assembly 23 , and a cathode side gas diffusion layer 24 . 1 and 2, the surface areas of the components decrease in the order of the anode-side porous flow path 10, the anode-side gas diffusion layer 22, the membrane electrode assembly 23, the cathode-side gas diffusion layer 24, and the cathode-side porous flow path 30, and the water electrolysis cell 100 has a pyramidal shape in the region where the membrane electrode assembly 23 is located. This minimizes gaps between the components, reducing differential pressure stress that occurs in the gaps. Since no gaps are provided on the oxygen electrode side where the pressure is low, it is possible to prevent components from penetrating into the gaps from the hydrogen electrode side where the pressure is high toward the oxygen electrode side where the pressure is low, thereby improving pressure resistance.

[0035] Figure 3 is a schematic plan view showing an example of some of the components of a water electrolysis cell according to the present disclosure. In Figure 3, the same components as those in Figure 1 are denoted by the same reference numerals, and their description will be omitted. The first frame 11 has a first anode side supply hole 61 , a first anode side discharge hole 62 , a first cathode side supply hole 63 , and a first cathode side discharge hole 64 . The second frame 21 has a second anode side supply hole 71 , a second anode side discharge hole 72 , a second cathode side supply hole 73 , and a second cathode side discharge hole 74 . The third frame 31 has a third anode side supply hole 81, a third anode side discharge hole 82, a third cathode side supply hole 83, and a third cathode side discharge hole 84. The first anode-side supply hole 61 of the first frame 11, the first opening that houses the anode-side porous flow path 10, and the first anode-side discharge hole 62 are connected in the planar direction to form a single connecting hole. The third cathode-side supply hole 83 of the third frame 31, the third opening that houses the cathode-side porous flow path 30, and the third cathode-side discharge hole 84 are connected in the planar direction to form a single communication hole. The anode-side porous flow channel 10 and the cathode-side porous flow channel 30 are also arranged in the region of the fluid inlet portion 51 and the region of the fluid outlet portion 52, which are regions indicated by the chain-line circles. The anode-side porous flow path 10 connects the first anode-side supply hole 61 and the first anode-side discharge hole 62 of the first frame 11 . The cathode porous flow path 30 connects the third cathode supply hole 83 and the third cathode discharge hole 84 of the third frame 31 . [Explanation of symbols]

[0036] 10. Anode side porous flow channel 11 First Frame 20 Membrane electrode gas diffusion layer assembly 21 2nd Frame 22 Anode side gas diffusion layer 23 Membrane electrode assembly 24 Cathode side gas diffusion layer 30 Cathode side porous flow channel 31 3rd Frame 40 Anode separator 50 Fluid inlet / outlet part 51 Fluid introduction section 52 Fluid outlet 61 First anode side supply hole 62 First anode side discharge hole 63 First cathode side supply hole 64 First cathode side discharge hole 71 Second anode side supply hole 72 Second anode side discharge hole 73 Second cathode side supply hole 74 Second cathode side discharge hole 81 Third anode side supply hole 82 Third anode side discharge hole 83 Third cathode side supply hole 84 Third cathode side discharge hole 100 water electrolysis cell

Claims

1. A water electrolysis cell, the water electrolysis cell includes, in this order, an anode-side porous flow path, a membrane electrode assembly, and a cathode-side porous flow path; the water electrolysis cell has a separator on at least one of a side of the anode-side porous flow channel opposite to the membrane electrode assembly side and a side of the cathode-side porous flow channel opposite to the membrane electrode assembly side, the membrane electrode assembly has, in order from the anode-side porous flow path side, an anode catalyst layer, an electrolyte membrane, and a cathode catalyst layer, an area of ​​the anode-side porous flow path in a planar direction is larger than an area of ​​the cathode-side porous flow path in a planar direction; the water electrolysis cell has an anode-side supply hole, a cathode-side supply hole, an anode-side discharge hole, and a cathode-side discharge hole at an end in a planar direction and in a region where the membrane electrode assembly is not present, in a plan view; the anode-side porous flow path connects the anode-side supply hole and the anode-side discharge hole; the cathode-side porous flow path connects the cathode-side supply hole and the cathode-side discharge hole; the cathode-side porous flow path is formed in a region extending from the cathode-side supply hole through the membrane electrode assembly to the cathode-side discharge hole in a plan view, a water electrolysis cell, wherein the anode-side porous flow path is formed in a region extending from the anode-side supply hole through the membrane electrode assembly to the anode-side discharge hole in a plan view.

2. The water electrolysis cell according to claim 1 , wherein each of the anode-side porous flow channel and the cathode-side porous flow channel is made of a metal porous member.

3. an anode-side gas diffusion layer is disposed between the anode-side porous flow path and the anode catalyst layer; a surface area of ​​the anode-side porous flow channel in a planar direction is larger than a surface area of ​​the anode-side gas diffusion layer in a planar direction; a cathode-side gas diffusion layer is disposed between the cathode-side porous flow path and the cathode catalyst layer; the cathode-side porous flow channel has a surface area smaller than the surface area of ​​the cathode-side gas diffusion layer; 2. The water electrolysis cell according to claim 1, wherein the anode-side gas diffusion layer has a larger area in a planar direction than the cathode-side gas diffusion layer, and the edge of the anode-side gas diffusion layer is located outward from the edge of the cathode-side gas diffusion layer along its entire periphery in a plan view.

4. the water electrolysis cell comprises a first frame having a first opening for accommodating the anode-side porous flow channel, a second frame having a second opening for accommodating the membrane electrode assembly, and a third frame having a third opening for accommodating the cathode-side porous flow channel, the first frame has a first anode side supply hole, a first cathode side supply hole, a first anode side discharge hole, and a first cathode side discharge hole at an end in a planar direction and in a region where the membrane electrode assembly is not present, in a plan view; the second frame has a second anode side supply hole, a second cathode side supply hole, a second anode side discharge hole, and a second cathode side discharge hole at an end in a planar direction and in a region where the membrane electrode assembly is not present, in a plan view; the third frame has a third anode-side supply hole, a third cathode-side supply hole, a third anode-side discharge hole, and a third cathode-side discharge hole at an end in a planar direction and in a region where the membrane electrode assembly is not present, in a plan view; the anode-side porous flow path connects the first anode-side supply hole and the first anode-side discharge hole of the first frame in a plan view; the cathode-side porous flow path connects the third cathode-side supply hole and the third cathode-side discharge hole of the third frame in a plan view; the anode side supply hole includes the first anode side supply hole, the second anode side supply hole, and the third anode side supply hole, the cathode supply hole includes the first cathode supply hole, the second cathode supply hole, and the third cathode supply hole, the anode-side discharge hole includes the first anode-side discharge hole, the second anode-side discharge hole, and the third anode-side discharge hole, 2 . The water electrolysis cell according to claim 1 , wherein the cathode discharge holes include the first cathode discharge hole, the second cathode discharge hole, and the third cathode discharge hole.

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