Membrane electrode assembly and water electrolysis cell

Abstract

To maintain a high permeation amount of water from an anode side to a cathode side through an electrolyte membrane as compared with a conventional water electrolysis apparatus in which an electrolyte is supplied only to the anode side.SOLUTION: The membrane-electrode assembly 30 includes the anion exchange membrane 33 including the first surface F1 and the second surface F2 opposite to each other, the cathode 31 facing the first surface F1, and the anode 32 facing the second surface F2, the cathode 31 exhibits higher hydrophilicity than the anode 32, the electrolytic solution is supplied to the anode 32 from the outside, and the electrolytic solution is not supplied to the cathode 31 from the outside.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a technology for water electrolysis using an electrolyte membrane. [Background technology]

[0002] Various technologies for producing hydrogen by water electrolysis using electrolyte membranes such as anion exchange membranes (AEMs) have been proposed. Conventional anion exchange membrane water electrolysis cells are operated by passing an electrolyte between the anode and cathode. Because an ionically conductive electrolyte is passed between both electrodes, a leakage current occurs between the anode and cathode via the electrolyte stored in an external storage device, causing corrosion and deterioration of the electrodes and cell components.

[0003] Patent Document 1 discloses a technique relating to a water electrolysis device in which an electrolytic solution is supplied only to the anode side. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2023-538279 Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology of Patent Document 1, the amount of water permeating from the anode side to the cathode side in the water electrolysis device is small, so the amount of water required for the reaction at the cathode is small. As a result, there is a concern that the amount of hydrogen generated by water electrolysis will be lower than in a method in which an electrolyte is passed through both electrodes.

[0006] In consideration of the above circumstances, one aspect of the present disclosure aims to maintain a high amount of water permeation through an electrolyte membrane from the anode side to the cathode side, as compared to a conventional water electrolysis device in which an electrolytic solution is supplied only to the anode side. [Means for solving the problem]

[0007] In order to solve the above problems, a membrane electrode assembly according to one embodiment of the present disclosure includes an anion exchange membrane having a first surface and a second surface opposite to each other, a cathode facing the first surface, and an anode facing the second surface, wherein the cathode exhibits higher hydrophilicity than the anode, and an electrolytic solution is supplied to the anode from an external source, while no electrolytic solution is supplied to the cathode from an external source.

[0008] A water electrolysis cell according to one aspect of the present disclosure includes an anion exchange membrane having a first surface and a second surface opposite to each other, a first flow path member facing the first surface, a cathode between the first surface and the first flow path member, a second flow path member facing the second surface, and an anode between the second surface and the second flow path member, wherein the cathode is more hydrophilic than the anode, and an electrolytic solution is supplied to the anode from an external source, while no electrolytic solution is supplied to the cathode from an external source. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a configuration diagram of a water electrolysis apparatus 100 according to a first embodiment. [Figure 2] FIG. 3 is an enlarged view of the cathode diffusion layer 312. [Figure 3] 1 is a graph showing the relationship between current density and voltage when the water electrolysis device 100 electrolyzes water. DETAILED DESCRIPTION OF THE INVENTION

[0010] The embodiments for carrying out the present disclosure will be described with reference to the drawings. Note that the dimensions and scale of each element in each drawing may differ from those of the actual product. Furthermore, the embodiment described below is an exemplary embodiment that may be envisioned when carrying out the present disclosure. Therefore, the scope of the present disclosure is not limited to the embodiment exemplified below.

[0011] 1: First embodiment 1 is a configuration diagram of a water electrolysis apparatus 100 according to a first embodiment. The water electrolysis apparatus 100 according to the first embodiment is a system that produces hydrogen and oxygen by water electrolysis, and includes a water electrolysis cell 21, a power supply device 22, a discharge mechanism 23, and a supply mechanism 24.

[0012] The water electrolysis cell 21 is a mechanism for producing hydrogen and oxygen by water electrolysis, and includes a membrane electrode assembly (MEA) 30, a first flow path member 41, a second flow path member 42, a first gasket 51, and a second gasket 52. The membrane electrode assembly 30 is installed between the first flow path member 41 and the second flow path member 42. Specifically, the first flow path member 41 and the second flow path member 42 are fixed to each other with fasteners such as screws or bolts, and the membrane electrode assembly 30 is sandwiched between the first flow path member 41 and the second flow path member 42.

[0013] The membrane electrode assembly 30 generates hydrogen and oxygen by water electrolysis. The membrane electrode assembly 30 of this embodiment is configured by laminating a cathode 31, an anode 32, and an anion exchange membrane 33. Specifically, the anion exchange membrane 33 is disposed between the cathode 31 and the anode 32.

[0014] The anion exchange membrane 33 (AEM) is an electrolyte membrane that allows selective migration of anions such as hydroxide ions (OH-). The anion exchange membrane 33 is formed from various polymer materials, such as A201 (manufactured by Tokuyama). However, the material of the anion exchange membrane 33 is arbitrary and is not limited to the above examples. For example, the anion exchange membrane 33 may be formed from a polymer material such as polyacrylonitrile (PAN), polysulfone (PS), polyvinyl alcohol (PVA), or polyethylene oxide (PEO).

[0015] The anion exchange membrane 33 of this embodiment is a rectangular thin film including a first surface F1 and a second surface F2. The first surface F1 and the second surface F2 are surfaces located on opposite sides of each other. The thickness of the anion exchange membrane 33 is, for example, about 30 μm.

[0016] The cathode 31 faces the first face F1. In the cathode 31, hydrogen gas is generated by a first reaction, which will be exemplified below. 4H2O+4e - →2H2+4OH -

[0017] As illustrated in FIG. 1 , the cathode 31 is composed of a laminate of a cathode catalyst layer 311 and a cathode diffusion layer 312. The cathode catalyst layer 311 is located between the first surface F1 and the cathode diffusion layer 312. The cathode catalyst layer 311 is a thin film that adheres to the first surface F1 and promotes the first reaction. The cathode catalyst layer 311 includes a catalyst active in the hydrogen generation reaction and an anion-conductive electrolyte. Examples of catalysts active in the hydrogen generation reaction include carbon supporting a metal material such as platinum (Pt) or a metal material such as nickel (Ni). Examples of anion-conductive electrolytes include polymer materials such as polyacrylonitrile (PAN), polysulfone (PS), polyvinyl alcohol (PVA), and polyethylene oxide (PEO). Here, the cathode catalyst layer 311 is an example of a “first catalyst layer.” The cathode diffusion layer 312 is an example of a “gas diffusion layer.” A catalyst active in the hydrogen generation reaction is an example of a "first catalyst."

[0018] The cathode diffusion layer 312 is an element for efficiently separating and discharging the hydrogen gas generated by the first reaction. For example, a layer made of a porous material such as nickel (Ni) foam or a carbon-based material is used as the cathode diffusion layer 312. The cathode diffusion layer 312 is also made of a conductive material and functions as a path for electrons exchanged with the cathode catalyst layer 311. The detailed configuration of the cathode diffusion layer 312 will be described later with reference to FIG. 2.

[0019] The anode 32 faces the second face F2. At the anode 32, oxygen gas is generated by the second reaction exemplified below. 4OH - →O2+2H2O+4e -

[0020] As illustrated in FIG. 1 , the anode 32 is composed of a laminate of an anode catalyst layer 321 and an anode diffusion layer 322. The anode catalyst layer 321 is located between the second surface F2 and the anode diffusion layer 322. The anode catalyst layer 321 is a thin film that adheres to the second surface F2 and promotes the second reaction. The anode catalyst layer 321 includes a catalyst active in the oxygen evolution reaction and an anion-conductive electrolyte. Examples of the catalyst active in the oxygen evolution reaction include metal materials such as iridium (Ir), iron (Fe), and nickel (Ni), as well as oxides of the metal materials listed above. As described above, examples of the anion-conductive electrolyte include polymer materials such as polyacrylonitrile (PAN), polysulfone (PS), polyvinyl alcohol (PVA), and polyethylene oxide (PEO). An anion exchange membrane 33 is located between the cathode catalyst layer 311 and the anode catalyst layer 321. Here, the anode catalyst layer 321 is an example of a "second catalyst layer." A catalyst active in the oxygen evolution reaction is an example of a "second catalyst."

[0021] The anode diffusion layer 322 is an element for efficiently separating and discharging oxygen gas generated by the second reaction. For example, a layer made of a porous material such as nickel (Ni) foam or a carbon-based material is used as the anode diffusion layer 322. The anode diffusion layer 322 also functions as an element for efficiently supplying the electrolyte to the anode catalyst layer 321 (and further to the anion exchange membrane 33). The anode diffusion layer 322 is also made of a conductive material and functions as a path for electrons exchanged with the anode catalyst layer 321.

[0022] The first flow path member 41 is a plate-shaped structure (separator) made of a conductive material such as metal. The first flow path member 41 faces the first surface F1 across the cathode 31. That is, the cathode 31 is located between the first surface F1 and the first flow path member 41.

[0023] A first flow path 411 is formed on a surface of the first flow path member 41 facing the first surface F1. The first flow path 411 is a flow path that communicates with the cathode 31. For example, hydrogen gas generated in the cathode 31 by the first reaction flows through the first flow path 411.

[0024] Furthermore, a first exhaust pipe 413 is installed in the first flow path member 41. The first exhaust pipe 413 is a pipe for discharging the hydrogen gas and water vapor generated by the first reaction.

[0025] The second flow path member 42 is a plate-shaped structure (separator) made of a conductive material such as metal. The second flow path member 42 faces the second surface F2 across the anode 32. That is, the anode 32 is located between the second surface F2 and the second flow path member 42.

[0026] A second flow path 421 is formed on the surface of the second flow path member 42 facing the second surface F2. The second flow path 421 is a flow path that communicates with the anode 32. For example, oxygen gas generated in the anode 32 by the second reaction flows through the second flow path 421. The second flow path 421 also functions as a path for flowing the electrolytic solution.

[0027] The second flow path member 42 is also provided with a second supply pipe 422 and a second discharge pipe 423. The second supply pipe 422 is a pipe for supplying the electrolytic solution to the water electrolysis cell 21. The second discharge pipe 423 is a pipe for discharging the oxygen gas generated by the second reaction and the excess electrolytic solution.

[0028] The first gasket 51 is a frame-shaped sealing member that seals the cathode 31 in the space between the first flow path member 41 and the anion exchange membrane 33 and surrounds the periphery of the cathode catalyst layer 311. Similarly, the second gasket 52 is a frame-shaped sealing member that seals the anode 32 in the space between the second flow path member 42 and the anion exchange membrane 33 and surrounds the periphery of the anode catalyst layer 321. The first gasket 51 and the second gasket 52 are formed from various elastic materials such as fluororubber (FKM), ethylene propylene diene rubber (EPDM), or polytetrafluoroethylene (PTFE).

[0029] The power supply device 22 is a DC power supply that supplies power to the water electrolysis cell 21. Specifically, the power supply device 22 is electrically connected to the first flow path member 41 and the second flow path member 42. The power supply device 22 of the first embodiment is a constant current source that controls the voltage across both ends so that a predetermined value of current is supplied to the water electrolysis cell 21. The power supply device 22 may also be electrically connected to the cathode 31 and the anode 32.

[0030] The supply mechanism 24 includes a second container 241 and a pump 242. The second container 241 is a container that stores an electrolytic solution. The electrolytic solution is, for example, pure water, tap water, or a basic aqueous solution. Examples of basic aqueous solutions include a mixture of pure water and potassium hydroxide (KOH), a mixture of pure water and sodium hydroxide (NaOH), and a mixture of pure water and potassium carbonate (K2CO3). The electrolytic solution in this embodiment is a mixture of pure water and potassium hydroxide. For example, an aqueous solution in which potassium hydroxide is mixed at a concentration of 1 M (mol / L) with pure water having a conductivity of about 20 μS / cm is used as the electrolytic solution.

[0031] The pump 242 is a liquid delivery mechanism that supplies the electrolytic solution stored in the second container 241 to the water electrolysis cell 21. Specifically, the pump 242 supplies the electrolytic solution in the second container 241 to the second supply pipe 422 of the second flow path member 42. The electrolytic solution delivered from the pump 242 is supplied to the second flow path 421 via the second supply pipe 422.

[0032] The electrolytic solution supplied to the second flow path 421 of the second flow path member 42 passes through the anode 32 and the anion exchange membrane 33 and reaches the cathode catalyst layer 311. When the power supply device 22 supplies power to the water electrolysis cell 21, oxygen gas is generated at the anode 32 by the second reaction using the electrolytic solution. The oxygen gas generated by the second reaction and excess electrolytic solution are discharged from the second discharge pipe 423 to the second container 241. The second container 241 functions as a gas-liquid separation tank that separates the oxygen gas from the electrolytic solution.

[0033] The discharge mechanism 23 includes a first container 231. The first container 231 is a container that stores an electrolytic solution. When the power supply 22 supplies power to the water electrolysis cell 21, hydrogen gas is generated in the cathode catalyst layer 311 by the first reaction described above, which uses the electrolytic solution supplied from the anode 32. The hydrogen gas and water vapor generated by the first reaction are discharged from the first discharge pipe 413 to the first container 231 via the cathode diffusion layer 312 and the first flow path member 41. The first container 231 functions as a gas-liquid separation tank that separates the hydrogen gas from the pure water.

[0034] As described above, when the power supply device 22 supplies power to the water electrolysis cell 21 and the electrolytic solution is supplied to the water electrolysis cell 21, the water electrolysis operation including the first reaction and the second reaction is carried out.

[0035] In this embodiment, the ion exchange capacity (IEC) of the anion conductive electrolyte contained in the cathode catalyst layer 311 is higher than that of the anion conductive electrolyte contained in the anode catalyst layer 321. For example, the ion exchange capacity of the anion conductive electrolyte contained in the cathode catalyst layer 311 is 2.0 meq / g, while the ion exchange capacity of the anion conductive electrolyte contained in the anode catalyst layer 321 is 1.5 meq / g. Alternatively, the blending ratio of the anion conductive electrolyte in the cathode catalyst layer 311 is higher than that of the anode catalyst layer 321. Therefore, the hydrophilicity of the cathode catalyst layer 311 is higher than that of the anode catalyst layer 321. In the membrane electrode assembly 30 according to this embodiment, the hydrophilicity of the cathode catalyst layer 311 is higher than that of the anode catalyst layer 321, and therefore, water permeation from the anode 32 to the cathode 31 via the anion exchange membrane 33 is promoted. It is more preferable that the hydrophilicity of the cathode catalyst layer 311 is higher than that of the anion exchange membrane 33 , and that the hydrophilicity of the anion exchange membrane 33 is higher than that of the anode catalyst layer 321 .

[0036] FIG. 2 is an enlarged view of the cathode diffusion layer 312. The cathode diffusion layer 312 is composed of a laminate of a carbon particle layer 312A and a carbon paper layer 312B containing carbon paper. The carbon particle layer 312A contacts the cathode catalyst layer 311. The carbon paper layer 312B is located between the carbon particle layer 312A and the first flow path member 41. The carbon paper layer 312B is an example of the "first layer." The carbon particle layer 312A is an example of the "second layer."

[0037] The presence of carbon particle layer 312A maintains cathode catalyst layer 311 as a layer. The surfaces of the particles that make up carbon particle layer 312A are made water-repellent, which allows hydrogen gas containing water vapor to easily permeate from carbon particle layer 312A to carbon paper layer 312B.

[0038] The carbon paper layer 312B is treated to be water-repellent. As an example, the carbon paper layer 312B is preferably carbon paper with a microporous layer (MPL) that has been treated to be water-repellent with polytetrafluoroethylene (PTFE) or perfluoroalkoxyalkane (PFA).

[0039] The diameter of the pores in carbon paper layer 312B is larger than the diameter of the path taken by hydrogen gas containing water vapor in carbon particle layer 312A, which makes it easier for hydrogen gas containing water vapor to move to first flow path member 41 via carbon paper layer 312B.

[0040] The water repellency of the cathode diffusion layer 312 is higher than that of the cathode catalyst layer 311. Therefore, the amount of water contained in the hydrogen gas moving from the cathode catalyst layer 311 to the cathode diffusion layer 312 is relatively small, while the amount of water contained in the electrolyte held in the cathode catalyst layer 311 is relatively large. The hydrogen gas discharged from the cathode diffusion layer 312 via the first flow path member 41 and the first discharge pipe 413 contains only a small amount of water vapor. Therefore, the water electrolysis apparatus 100 according to this embodiment can produce high-quality hydrogen gas. Furthermore, in the water electrolysis apparatus 100 according to this embodiment, the first container 231 functioning as a gas-liquid separation tank can be made smaller. Alternatively, the first container 231 may be omitted from the water electrolysis apparatus 100 according to this embodiment. Furthermore, since the water repellency of the cathode diffusion layer 312 is higher than that of the cathode catalyst layer 311, the cathode catalyst layer 311 can retain a large amount of water, thereby ensuring a large amount of hydrogen to be generated by water electrolysis.

[0041] Furthermore, in this embodiment, the electrolytic solution stored in the second container 241 is supplied to the second flow path 421 by the pump 242, and the electrolytic solution supplied to the second flow path 421 reaches the anode 32. On the other hand, the electrolytic solution contained in the cathode catalyst layer 311 does not reach the first flow path member 41. Furthermore, the electrolytic solution stored in a storage device external to the water electrolysis cell 21 is not supplied to the cathode 31. Therefore, a leak current circuit is not formed between the cathode 31 and the anode 32 via the electrolytic solution stored in the external storage device, and no leak current is generated. As a result, the water electrolysis device 100 according to this embodiment can suppress corrosion and deterioration of the electrodes and cell components due to leak current.

[0042] Fig. 3 is a graph showing the relationship between current density and voltage when water is electrolyzed by the water electrolysis apparatus 100 according to this embodiment. In preparing the graph of Fig. 3, a 1 M KOH aqueous solution was used as the electrolyte and passed through the anode 32 at a rate of 10 ml / min. The power supply 22 supplied a current of 0.0 to 2.0 A / cm. 2Before operation of the water electrolysis apparatus 100, the water was purged with dry nitrogen to prevent explosion due to mixing with oxygen.

[0043] In the graph of Fig. 3, the current density on the horizontal axis corresponds to the amount of hydrogen gas produced. As shown in the graph of Fig. 3, in the water electrolysis device 100 according to this embodiment, even when the electrolyte is passed only through the anode 32 side, a high current density is achieved even at a low voltage, and as a result, a large amount of hydrogen gas is produced. Specifically, in the water electrolysis device 100 according to this embodiment, the current density at a voltage of 1.8 V is 2.0 A / cm 2 The reason why a large amount of hydrogen gas was obtained even at a low voltage without passing an electrolyte solution on the cathode 31 side is thought to be that the increased hydrophilicity on the cathode 31 side promoted the permeation of water from the anode 32 side through the anion exchange membrane 33, and the suppression of water discharge from the cathode 31 side allowed a sufficient amount of water required for the reaction to be supplied to the cathode catalyst layer 311.

[0044] Furthermore, when the first discharge pipe 413 was observed near the outlet of the first flow path member 41, no liquid droplets were found. Although water is contained on the cathode 31 side, it is believed that it is not discharged as liquid droplets because it is decomposed in the water electrolysis reaction. From this, it is believed that only a small amount of water vapor is contained in the hydrogen generated on the cathode 31 side. Therefore, it is possible to reduce the size of the first container 231 as a gas-liquid separator or to omit it, which is expected to reduce costs.

[0045] In addition, the term "nth" (n is a natural number) in this application is used only as a formal and convenient label to distinguish each element in the description and does not have any substantive meaning. Therefore, there is no room for restrictive interpretation of the position of each element or the order of production, etc., based on the term "nth."

[0046] 2: Supplementary Note From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0047] A membrane electrode assembly according to one embodiment (embodiment 1) of the present disclosure includes an anion exchange membrane having a first surface and a second surface opposite to each other, a cathode facing the first surface, and an anode facing the second surface. The cathode exhibits higher hydrophilicity than the anode. An electrolytic solution is supplied to the anode from an external source, while the cathode is not supplied with an electrolytic solution from an external source. Because the flow paths and the like outside the cathode can be kept dry with few liquid droplets, the cost of the water electrolysis cell 21 can be reduced by downsizing or omitting a gas-liquid separator on the cathode side. Furthermore, because the hydrophilicity of the cathode is higher than that of the anode, water flow from the anode through the electrolyte membrane can be promoted, thereby maintaining high performance. Furthermore, by supplying the electrolytic solution only to the anode, a circuit for leakage current due to ionic conduction between the cathode and the electrolytic solution is not formed. As a result, the membrane electrode assembly according to embodiment 1 can prevent leakage current and suppress corrosion and deterioration of the electrodes and cell components.

[0048] In a specific example (Aspect 2) of Aspect 1, the cathode includes a first catalyst layer and a gas diffusion layer, and the first catalyst layer includes a first catalyst active in the hydrogen generation reaction and an anion-conductive electrolyte. The first catalyst layer includes the first catalyst active in the hydrogen generation reaction, thereby enabling hydrogen to be generated.

[0049] In a specific example (Aspect 3) of Aspect 2, the anode contains an anion-conductive electrolyte, and the ion exchange capacity of the anion-conductive electrolyte contained in the cathode is higher than the ion exchange capacity of the anion-conductive electrolyte contained in the anode. By making the ion exchange capacity of the anion-conductive electrolyte contained in the cathode higher than the ion exchange capacity of the anion-conductive electrolyte contained in the anode, the hydrophilicity of the cathode can be made higher than the hydrophilicity of the anode. As a result, the amount of water passing from the anode to the cathode can be increased.

[0050] In a specific example (Aspect 4) of Aspect 2 or Aspect 3, the anode contains an anion-conductive electrolyte, and the blend ratio of the anion-conductive electrolyte in the cathode is higher than the blend ratio of the anion-conductive electrolyte in the anode. By making the blend ratio of the anion-conductive electrolyte in the cathode higher than the blend ratio of the anion-conductive electrolyte in the anode, the hydrophilicity of the cathode can be made higher than the hydrophilicity of the anode. As a result, the amount of water passing from the anode to the cathode can be increased.

[0051] In a specific example (Aspect 5) of any of Aspects 2 to 4, the gas diffusion layer comprises a first layer containing carbon paper and a second layer that is a carbon particle layer, and has higher water repellency than the first catalyst layer. Because the electrolyte does not come into contact with the cathode, leakage current is prevented and corrosion degradation of the electrodes and cell components can be suppressed. Furthermore, because the gas diffusion layer has higher water repellency than the first catalyst layer, the first catalyst layer can retain more moisture, making it possible to reduce the amount of moisture contained in the gas that permeates to the separator side.

[0052] In a specific example (Aspect 6) of any one of Aspects 1 to 5, the anode includes a second catalyst layer, and the second catalyst layer includes a second catalyst active in the oxygen evolution reaction and an anion-conductive electrolyte. When the second catalyst layer includes the first catalyst active in the oxygen evolution reaction, water can be produced from hydroxide ions.

[0053] In a specific example (Aspect 7) of any of Aspects 1 to 6, the electrolytic solution is any of a basic aqueous solution, pure water, and tap water. The membrane electrode assembly according to Aspect 7 can generate hydrogen by electrolyzing water contained in the electrolytic solution.

[0054] A water electrolysis cell 21 according to one embodiment (embodiment 8) of the present disclosure includes an anion exchange membrane having a first surface and a second surface opposite to each other; a first flow path member facing the first surface and including a flow path through which hydrogen is discharged; a cathode between the first surface and the first flow path member; a second flow path member facing the second surface and including a flow path through which an electrolyte solution is supplied; and an anode between the second surface and the second flow path member. The cathode exhibits higher hydrophilicity than the anode. The electrolyte solution is supplied to the anode from an external source, but the cathode is not supplied with the electrolyte solution from an external source. Because the flow path outside the cathode can be kept dry with few liquid droplets, the cost of the water electrolysis cell 21 can be reduced by downsizing or omitting a gas-liquid separator on the cathode side. Furthermore, because the hydrophilicity of the cathode is higher than that of the anode, water flow from the anode through the electrolyte membrane can be promoted, thereby maintaining high performance. Furthermore, supplying the electrolyte only to the anode prevents the formation of a circuit for leakage current due to ionic conduction via the cathode and the electrolyte, thereby enabling the water electrolysis cell 21 according to aspect 8 to prevent leakage current and suppress corrosion and deterioration of the electrodes and cell components. [Explanation of symbols]

[0055] 21...water electrolysis cell, 22...power supply device, 23...discharge mechanism, 24...supply mechanism, 30...membrane electrode assembly, 31...cathode portion, 32...anode portion, 33...anion exchange membrane, 41...first flow path member, 42...second flow path member, 51...first gasket, 52...second gasket, 100...water electrolysis device, 231...first container, 241...second container, 242...pump, 311...cathode catalyst layer, 312...cathode diffusion layer, 312A...carbon particle layer, 312B...carbon paper layer, 321...anode catalyst layer, 322...anode diffusion layer, 411...first flow path, 413...first discharge pipe, 421...second flow path, 422...second supply pipe, 423...second discharge pipe, F1...first surface, F2...second surface

Claims

1. an anion exchange membrane including a first side and a second side opposite each other; a cathode facing the first surface; an anode facing the second surface; Equipped with the cathode exhibits greater hydrophilicity than the anode; An electrolyte is supplied to the anode from the outside, No electrolyte is supplied to the cathode from the outside. Membrane electrode assembly.

2. the cathode comprises a first catalyst layer and a gas diffusion layer; The first catalyst layer is a first catalyst active in a hydrogen generation reaction; an anion-conductive electrolyte; Including, The membrane electrode assembly according to claim 1 .

3. the anode comprises an anion-conducting electrolyte; The ion exchange capacity of the anion-conductive electrolyte contained in the cathode is higher than the ion exchange capacity of the anion-conducting electrolyte contained in the anode; The membrane electrode assembly according to claim 2 .

4. the anode comprises an anion-conducting electrolyte; The compounding ratio of the anion conductive electrolyte in the cathode is: higher than the blending ratio of the anion conductive electrolyte in the anode; The membrane electrode assembly according to claim 2 .

5. The gas diffusion layer is a first layer comprising carbon paper; a second layer which is a carbon particle layer; Equipped with has higher water repellency than the first catalyst layer; The membrane electrode assembly according to claim 2 .

6. the anode comprises a second catalyst layer; The second catalyst layer is a second catalyst active in the oxygen evolution reaction; an anion-conductive electrolyte; Including, The membrane electrode assembly according to claim 1 .

7. The electrolyte is any one of a basic aqueous solution, pure water, and tap water. The membrane electrode assembly according to claim 1 .

8. an anion exchange membrane including a first side and a second side opposite each other; a first flow path member facing the first surface and including a flow path through which hydrogen is discharged; a cathode between the first surface and the first flow path member; a second flow path member facing the second surface and including a flow path through which an electrolytic solution is supplied; an anode between the second surface and the second flow path member; Equipped with the cathode exhibits greater hydrophilicity than the anode; An electrolyte is supplied to the anode from the outside, No electrolyte is supplied to the cathode from the outside. water electrolysis cell.

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