Catalyst-coated membrane, water electrolyzer, and method for producing catalyst-coated membrane

Abstract

To provide a technique capable of smoothing replacement of gas and liquid in a catalyst layer.SOLUTION: The membrane-catalyst layer assembly includes an electrolyte membrane and a catalyst layer formed on a surface of the electrolyte membrane. The catalyst layer comprises a first ionomer 83 and a second ionomer 84. The EW value of the second ionomer 84 is higher than the EW value of the first ionomer 83. In this way, a first region A1 having a relatively high hydrophilicity due to the first ionomer 83 and a second region A2 having a relatively low hydrophilicity due to the second ionomer 84 are formed. As a result, gas-liquid exchange can be smoothly performed in the catalyst layer.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a membrane-catalyst layer assembly, a water electrolysis device, and a method for producing a membrane-catalyst layer assembly. [Background technology]

[0002] Conventionally, a PEM (Proton Exchange Membrane) type water electrolysis device is known that produces hydrogen (H) by electrolyzing water (H2O). This type of water electrolysis device has a cell stack in which cells and separators are alternately stacked. Each cell has an electrolyte membrane and catalyst layers formed on both sides of the electrolyte membrane.

[0003] When the water electrolysis device is in use, a voltage is applied between the anode catalyst layer and the cathode catalyst layer, and water is supplied to the anode catalyst layer. This causes the following electrochemical reaction to occur between the anode catalyst layer and the cathode catalyst layer. As a result, hydrogen is discharged from the cathode catalyst layer. (Anode side) 2H2O → 4H + + O2+ 4e - (Cathode side) 2H + + 2e - → H2

[0004] Conventional water electrolysis devices are described in, for example, Patent Documents 1 and 2. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-023996 [Patent Document 2] Japanese Patent Publication No. 2023-041182 Summary of the Invention [Problem to be solved by the invention]

[0006] When the water electrolysis device is in use, as described above, water is converted into hydrogen ions (H + ), oxygen (O2), and electrons (e - ) is electrolyzed into the anode-side catalyst layer. Therefore, it is necessary to supply liquid water and discharge gaseous oxygen to the anode-side catalyst layer. However, the discharge of oxygen may be hindered by the influence of water supplied to the catalyst layer. In such cases, the efficiency of electrolysis on the anode side decreases due to the reduced discharge of oxygen.

[0007] In Patent Document 2, the oxygen discharge from the catalyst layer is improved by adding water-repellent particles to the anode catalyst layer in addition to catalyst particles and an ionomer. However, this method has the problem that the ionic conductivity of the catalyst layer is reduced by adding the water-repellent particles.

[0008] Therefore, an object of the present invention is to provide a technique that can facilitate the exchange of gas and liquid in a catalyst layer using a method different from that of Patent Document 2. [Means for solving the problem]

[0009] A first invention is a membrane-catalyst layer assembly comprising an electrolyte membrane and a catalyst layer formed on a surface of the electrolyte membrane, the catalyst layer including a first ionomer and a second ionomer having an EW value higher than that of the first ionomer.

[0010] A second invention is the membrane-catalyst layer assembly of the first invention, wherein the weight ratio of the first ionomer in the catalyst layer is greater than the weight ratio of the second ionomer in the catalyst layer.

[0011] A third invention is a membrane-catalyst layer assembly according to the first or second invention, wherein the side chains of the first ionomer and the side chains of the second ionomer have the same structure, and the polymerization number of tetrafluoroethylene in the main chain of the second ionomer is greater than the polymerization number of tetrafluoroethylene in the main chain of the first ionomer.

[0012] A fourth invention is a membrane-catalyst layer assembly according to any one of the first to third inventions, wherein the EW value of the second ionomer is greater than the EW value of the first ionomer by 100 [g / mol] or more.

[0013] A fifth invention is the membrane-catalyst layer assembly of the fourth invention, wherein the EW value of the first ionomer is 900 [g / mol] or less, and the EW value of the second ionomer is 1200 [g / mol] or more.

[0014] A sixth aspect of the present invention is a water electrolysis apparatus, which comprises the membrane-catalyst layer assembly of any one of the first to fifth aspects of the present invention.

[0015] A seventh invention is a method for manufacturing a membrane-catalyst-layer assembly, comprising: a first step of preparing a catalyst ink by mixing catalyst particles, a solvent, and an ionomer; a second step of applying the catalyst ink to the surface of an electrolyte membrane; and a third step of forming a catalyst layer by drying the catalyst ink applied to the electrolyte membrane, wherein the ionomer includes a first ionomer and a second ionomer having an EW value higher than that of the first ionomer. [Effects of the Invention]

[0016] According to the first to seventh inventions, a first region having relatively high hydrophilicity due to the first ionomer and a second region having relatively low hydrophilicity due to the second ionomer are formed in the catalyst layer, thereby enabling smooth gas-liquid exchange in the catalyst layer.

[0017] In particular, according to the second aspect of the present invention, the ion conduction efficiency of the catalyst layer can be improved. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram of a water electrolysis device. [Figure 2] FIG. 1 is a schematic diagram of one cell and a pair of separators located on either side of the cell. [Figure 3] FIG. 1 is a diagram showing the molecular structure of an ionomer. [Figure 4] FIG. 2 is a diagram schematically illustrating a portion of an anode catalyst layer. [Figure 5] 1 is a flowchart showing a manufacturing procedure for an anode catalyst layer. [Figure 6] FIG. 10 is a diagram showing an example of a manufacturing device for performing the second and third steps. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] <1. Water electrolysis device according to one embodiment> Fig. 1 is a schematic diagram of a PEM water electrolysis system 1 according to one embodiment of the present invention. This water electrolysis system 1 is a system for producing hydrogen by water electrolysis. As shown in Fig. 1, the water electrolysis system 1 includes a cell stack 30 composed of a plurality of cells 10 and a plurality of separators 20, and a power supply device 40 that applies a voltage to the cell stack 30. The cells 10 and the separators 20 are alternately stacked to form the cell stack 30.

[0021] 2 is a schematic diagram illustrating only one cell 10 and a pair of separators 20 located on either side of the cell 10 in the cell stack 30 of the water electrolysis device 1. As shown in FIG. 2, one cell 10 has an electrolyte membrane 51, an anode catalyst layer 61, a porous transport layer 62, a cathode catalyst layer 71, and a gas diffusion layer 72.

[0022] A laminate composed of the electrolyte membrane 51, the anode catalyst layer 61, and the cathode catalyst layer 71 is called a catalyst-coated membrane (CCM). A laminate composed of the electrolyte membrane 51, the anode catalyst layer 61, the porous transport layer 62, the cathode catalyst layer 71, and the gas diffusion layer 72 is called a membrane-electrode-assembly (MEA).

[0023] The electrolyte membrane 51 is a thin membrane (ion exchange membrane) having ion conductivity. The electrolyte membrane 51 of this embodiment is a membrane that exchanges hydrogen ions (H + ) is a proton exchange membrane that conducts a current. A fluorine-based or hydrocarbon-based polymer electrolyte membrane is used as the electrolyte membrane 51. Specifically, for example, a solid polymer electrolyte membrane containing perfluorocarbon sulfonic acid is used as the electrolyte membrane 51. The thickness of the electrolyte membrane 51 is, for example, 5 μm to 200 μm.

[0024] The anode catalyst layer 61 is a catalyst layer that causes water electrolysis on the anode side of the electrolyte membrane 51. The anode catalyst layer 61 is formed on the anode side surface of the electrolyte membrane 51. The anode catalyst layer 61 contains a large number of catalyst particles and an ionomer.

[0025] The catalyst particles are particles that have catalytic activity for causing the electrolysis of water. The catalyst particles are made of, for example, iridium (Ir), ruthenium (Ru), iridium oxide (IrOx), platinum (Pt), or an alloy of iridium (Ir) and ruthenium (Ru). The catalyst particles may be supported by a support. In this case, the support may be, for example, titanium dioxide (TiO2) or carbon (C).

[0026] The ionomer is an electrolyte polymer that covers the catalyst particles. The ionomer plays a role in transporting hydrogen ions generated by the electrolysis of water within the anode catalyst layer 61. For example, Nafion (perfluorocarbon sulfonic acid) is used as the ionomer. The ionomer has a polymer chain structure with ion exchange groups such as sulfo groups. The hydrogen ions combine with water within the anode catalyst layer 61 to form oxonium ions (HO + ) Then, the oxonium ion propagates through the ion exchange groups of the ionomer.

[0027] When the water electrolysis device 1 is in use, water (H2O) is supplied to the anode catalyst layer 61. Then, a voltage is applied between the anode catalyst layer 61 and the cathode catalyst layer 71 by the power supply device 40. Then, due to the action of the voltage and the catalyst particles, the water is converted into hydrogen ions (H + ), oxygen (O2), and electrons (e - That is, in the anode catalyst layer 61, the following electrochemical reaction occurs: 2H2O → 4H + + O2+ 4e - (1)

[0028] The porous transport layer (PTL) 62 is a layer that uniformly supplies water from the separator 20 to the anode catalyst layer 61 and transports oxygen and electrons generated in the anode catalyst layer 61 to the separator 20. The porous transport layer 62 is laminated on the outer side of the anode catalyst layer 61 (the side opposite the electrolyte membrane 51). The porous transport layer 62 is made of a conductive and porous material. For example, a porous substrate made of metallic titanium or a titanium alloy is used for the porous transport layer 62.

[0029] The cathode catalyst layer 71 is a catalyst layer that causes a hydrogen reduction reaction on the cathode side of the electrolyte membrane 51. The cathode catalyst layer 71 is formed on the cathode side surface of the electrolyte membrane 51 (the surface opposite to the surface on which the anode catalyst layer 61 is formed). The cathode catalyst layer 71 contains a large number of carbon particles that support catalyst particles. The catalyst particles are, for example, platinum particles. However, the catalyst particles may also be platinum particles mixed with a small amount of ruthenium or cobalt particles.

[0030] When the water electrolysis device 1 is in use, hydrogen ions (H + ) and electrons (e -) is supplied. Then, a voltage is applied between the anode catalyst layer 61 and the cathode catalyst layer 71 by the power supply device 40. This voltage and the action of the catalyst particles cause a reduction reaction in the cathode catalyst layer 71, producing hydrogen gas (H2) from the hydrogen ions and electrons. That is, the following electrochemical reaction occurs in the cathode catalyst layer 71: 2H + + 2e - → H2(2)

[0031] The gas diffusion layer (GDL) 72 is a layer that transfers electrons from the separator 20 to the cathode catalyst layer 71 and transfers hydrogen generated in the cathode catalyst layer 71 to the separator 20. The gas diffusion layer 72 is laminated on the outer side of the cathode catalyst layer 71 (the side opposite to the electrolyte membrane 51). The gas diffusion layer 72 is made of a conductive and porous material. For example, a porous substrate made of carbon (carbon paper) is used for the gas diffusion layer 72.

[0032] The separator 20 is a layer that transfers electrons between adjacent cells 10 and also forms paths for water, oxygen, and hydrogen. The separator 20 is interposed between the porous transport layer 62 and the gas diffusion layer 72 of adjacent cells 10. The separator 20 is made of a material that is electrically conductive and impermeable to gases and liquids. For example, a metal plate is used as the separator 20.

[0033] Separator 20 has an anode surface 21 in contact with porous transport layer 62 and a cathode surface 22 in contact with gas diffusion layer 72. A plurality of anode grooves 23 are formed on anode surface 21. Water is supplied from outside cell stack 30 to porous transport layer 62 through anode grooves 23 of separator 20. Oxygen generated in anode catalyst layer 61 passes through porous transport layer 62 and anode grooves 23 of separator 20, and is discharged to outside cell stack 30.

[0034] In addition, a plurality of cathode grooves 24 are formed on the cathode surface 22 of the separator 20. Hydrogen generated in the cathode catalyst layer 71 passes through the gas diffusion layer 72 and the cathode grooves 24 of the separator 20, and is discharged to the outside of the cell stack 30.

[0035] The power supply 40 is a device that applies a voltage to the above-mentioned cell stack 30. As shown in Fig. 1, the positive terminal of the power supply 40 is electrically connected to the separator 20 located at the end of the cell stack 30 closest to the anode. The negative terminal of the power supply 40 is electrically connected to the separator 20 located at the end of the cell stack 30 closest to the cathode. The power supply 40 applies a voltage required for water electrolysis to the cell stack 30.

[0036] When the water electrolysis device 1 is in use, water is supplied from the anode grooves 23 of the separator 20 through the porous transport layer 62 to the anode catalyst layer 61. Then, due to the voltage from the power supply 40 and the action of the catalyst particles in the anode catalyst layer 61, the water is decomposed into hydrogen ions, oxygen, and electrons. The hydrogen ions propagate through the electrolyte membrane 51 to the cathode catalyst layer 71. The oxygen passes through the porous transport layer 62 and the anode grooves 23 and is discharged to the outside of the cell stack 30. The electrons flow through the porous transport layer 62 and the separator 20 to the adjacent cell 10.

[0037] In the adjacent cell 10, the electrons pass through the gas diffusion layer 72 and reach the cathode catalyst layer 71. Then, in the cathode catalyst layer 71, the hydrogen ions and electrons combine to generate hydrogen. The generated hydrogen passes through the gas diffusion layer 72 and the cathode groove 24 and is discharged to the outside of the cell stack 30. In this way, hydrogen is produced.

[0038] <2. Anode catalyst layer> Next, the above-mentioned anode catalyst layer 61 will be described in more detail. The anode catalyst layer 61 is an example of the "catalyst layer" in the present invention. As described above, the anode catalyst layer 61 contains a large number of catalyst particles and an ionomer.

[0039] FIG. 3 is a diagram showing the molecular structure of an ionomer. An ionomer has a structure in which a large number of monomers 80, which are constituent units, are linked by polymerization. In FIG. 3, the number of polymerizations of the monomers 80 is represented by the symbol n. As shown in FIG. 3, the monomers 80 have a main chain 81 and a side chain 82. In an ionomer, adjacent main chains 81 are bonded to each other to form a polymer.

[0040] As shown in Fig. 3, the main chain 81 of the ionomer contains polytetrafluoroethylene (PTFE). Polytetrafluoroethylene is formed by polymerizing a plurality of tetrafluoroethylenes (TFE, C2F4). In Fig. 3, the number of polymerizations of tetrafluoroethylene in the main chain 81 of one monomer 80 is represented by the symbol m. The value of m is, for example, about 3 to 9.

[0041] The side chains 82 extend laterally from the main chain 81. In the example of FIG. 3, one monomer 80 has one side chain 82. The side chain 82 has a sulfo group (SO3H) at its end, which is an ion exchange group. Hydrogen ions generated by the electrolysis of water combine with water in the anode catalyst layer 61 to form oxonium ions (HO + ) Then, the oxonium ion propagates through the sulfo group. In other words, the ionomer conducts ions through the sulfo group.

[0042] Here, the EW (Equivalent Weight) value of an ionomer will be explained. The EW value is a value that indicates the dry mass of an ionomer per 1 mole of ion exchange groups. In other words, the EW value indicates the reciprocal of the number of ion exchange groups per unit mass of the ionomer. The EW value can be expressed by the following mathematical formula (1). EW [g / mol] = dry mass of ionomer [g] / number of moles of sulfo groups [mol] (1)

[0043] The EW value increases in proportion to the number of polymerizations m of tetrafluoroethylene in the main chain 81. Since the molar mass of tetrafluoroethylene is approximately 100 [g / mol], the EW value can also be expressed by the following formula (2): MW side-chain in formula (2) represents the molar mass of the side chain 82. EW[g / mol]=100[g / mol]×m+MWside-chain[g / mol] (2)

[0044] The lower the EW value of an ionomer, the higher the proportion of ion exchange groups. Therefore, the lower the EW value of an ionomer, the higher the ionic conductivity and hydrophilicity. Conversely, the higher the EW value of an ionomer, the lower the proportion of ion exchange groups. Therefore, the higher the EW value of an ionomer, the lower the ionic conductivity and hydrophobicity.

[0045] The ionomer of this embodiment contains two types of ionomers with different EW values. Hereinafter, of the two types of ionomers, the ionomer with the lower EW value will be referred to as "first ionomer 83," and the ionomer with the higher EW value will be referred to as "second ionomer 84." The first ionomer 83 has higher ionic conductivity and higher hydrophilicity than the second ionomer 84.

[0046] Fig. 4 is a schematic diagram showing a portion of an anode catalyst layer 61. As shown in Fig. 4, the anode catalyst layer 61 of this embodiment has a first region A1 in which the first ionomer 83 is present in a greater amount than the second ionomer 84, and a second region A2 in which the second ionomer 84 is present in a greater amount than the first ionomer 83. The first region A1 has higher hydrophilicity than the second region A2 due to the first ionomer 83. The second region A2 has lower hydrophilicity than the first region A1 due to the second ionomer 84.

[0047] When the water electrolysis device 1 is in use, water (HO) is converted into hydrogen ions (H + ), oxygen (O2), and electrons (e -) is electrolyzed into water. For this reason, it is necessary to supply liquid water to the anode catalyst layer 61 and discharge gaseous oxygen therefrom. In this case, according to this embodiment, as shown in FIG. 4, the first region A1 in the anode catalyst layer 61, which has high hydrophilicity, serves as a water supply path. Furthermore, the second region A2 in the anode catalyst layer 61, which has low hydrophilicity, serves as an oxygen discharge path.

[0048] As described above, according to this embodiment, the anode catalyst layer 61 can be divided into the first region A1, which serves as a water supply path, and the second region A2, which serves as an oxygen discharge path. This allows smooth exchange of gas and liquid in the anode catalyst layer 61. As a result, electrolysis can be performed efficiently in the anode catalyst layer 61. In other words, the efficiency of electrolysis in the anode catalyst layer 61 can be improved without adding any additives other than the catalyst particles and ionomer.

[0049] In the water electrolysis device 1, the reaction rate of electrolysis in the anode catalyst layer 61 is often slower than the reduction reaction rate in the cathode catalyst layer 71. Therefore, the overall treatment rate of the water electrolysis device 1 is often determined by the reaction rate on the anode side. However, by including two types of ionomers with different EW values ​​in the anode catalyst layer 61 as in the present embodiment, the reaction rate of electrolysis in the anode catalyst layer 61 can be increased as described above. As a result, the overall treatment rate of the water electrolysis device 1 can be improved.

[0050] However, if the proportion of the second ionomer 84 in the anode catalyst layer 61 is too high, the ionic conductivity of the ionomer will decrease. Therefore, from the viewpoint of ionic conductivity, it is desirable to blend a larger amount of the first ionomer 83 than the second ionomer 84. Specifically, it is desirable to make the weight ratio of the first ionomer 83 in the anode catalyst layer 61 greater than the weight ratio of the second ionomer 84 in the anode catalyst layer 61. For example, it is desirable to set the weight ratio of the second ionomer 84 to the total amount of ionomers to be 10 wt % or more and less than 50 wt %. This can improve the ionic conduction efficiency of the anode catalyst layer 61.

[0051] When side chains 82 of first ionomer 83 and side chains 82 of second ionomer 84 have the same structure, as shown in the above-mentioned formula (2), the EW value increases in proportion to the polymerization number m of tetrafluoroethylene in main chain 81. Therefore, if the structures of side chains 82 are the same, second ionomer 84 should be one having a larger polymerization number m of tetrafluoroethylene in main chain 81 than first ionomer 83.

[0052] Furthermore, the EW value of the second ionomer 84 is desirably at least 100 [g / mol] greater than the EW value of the first ionomer 83. When the side chains 82 of the first ionomer 83 and the side chains 82 of the second ionomer 84 have the same structure, a difference in EW value of at least 100 [g / mol] means that the polymerization number m of tetrafluoroethylene in the main chain 81 differs by at least 1. This allows the first region A1 and the second region A2, which have different hydrophilicity, to be successfully formed in the anode catalyst layer 61.

[0053] Moreover, the EW value of the second ionomer 84 is more preferably 200 [g / mol] or more greater than the EW value of the first ionomer 83. Moreover, the EW value of the second ionomer 84 is even more preferably 300 [g / mol] or more greater than the EW value of the first ionomer 83.

[0054] The EW value of the first ionomer 83 may be, for example, 900 [g / mol] or less. Specifically, the EW value of the first ionomer 83 may be 800 [g / mol] or more and 900 [g / mol] or less. The EW value of the second ionomer 84 may be, for example, 1200 [g / mol] or more. Specifically, the EW value of the second ionomer 84 may be 1200 [g / mol] or more and 1400 [g / mol] or less.

[0055] 3. Method for manufacturing membrane-catalyst layer assembly The anode catalyst layer 61 is formed by applying and drying catalyst ink on the surface of the electrolyte membrane 51. A method for producing a membrane-catalyst layer assembly including the anode catalyst layer 61 will be described below.

[0056] Fig. 5 is a flowchart showing the procedure for producing the anode catalyst layer 61. As shown in Fig. 5, when producing the anode catalyst layer 61, first, a catalyst ink for the anode catalyst layer 61 is prepared (first step S1).

[0057] In the first step S1, a plurality of catalyst particles and an ionomer are added to a solvent and mixed by stirring. The solvent is water, alcohol, or both. Examples of alcohol include methanol, ethanol, 1-propanol, and 2-propanol. The amount of solvent is set so that the solids concentration in the catalyst ink is 1% or more and 20% or less.

[0058] The ionomer includes a first ionomer 83 and a second ionomer 84. The EW value of the second ionomer 84 is higher than the EW value of the first ionomer 83. The weight ratio of the ionomer including the first ionomer 83 and the second ionomer 84 to the catalyst particles is, for example, 1 wt% or more and 50 wt% or less, and desirably 10 wt% or more and 30 wt% or less.

[0059] Next, the catalyst ink prepared in the first step S1 is applied to the surface of the electrolyte membrane 51 (second step S2). FIG. 6 is a diagram showing an example of a manufacturing apparatus 90 that performs the second step S2 and the third step S3 described below. The manufacturing apparatus 90 in FIG. 6 has a nozzle 91 that ejects the catalyst ink and a transport mechanism 92 that moves the electrolyte membrane 51 relative to the nozzle 91. The nozzle 91 may eject the catalyst ink in the form of a film from a slit-shaped outlet, or may eject the catalyst ink in the form of a spray.

[0060] The manufacturing apparatus 90 ejects catalyst ink from a nozzle 91 onto the surface of the electrolyte membrane 51 while transporting the electrolyte membrane 51 using a transport mechanism 92. In this way, the catalyst ink is applied to the surface of the electrolyte membrane 51.

[0061] After the second step S2 is completed, the catalyst ink applied to the electrolyte membrane 51 is dried (third step S3). In the manufacturing apparatus 90 of FIG. 6, the electrolyte membrane 51 to which the catalyst ink has been applied is transported to a drying oven 93 by a transport mechanism 92. The temperature inside the drying oven 93 is higher than the ambient temperature, which promotes evaporation of the solvent in the catalyst ink. This dries the catalyst ink. As a result, an anode catalyst layer 61 is formed on the surface of the electrolyte membrane 51.

[0062] Thereafter, a water electrolysis device 1 is manufactured using a membrane-catalyst layer assembly including the electrolyte membrane 51 and the above-described anode catalyst layer 61. Specifically, a porous transport layer 62 and a gas diffusion layer 72 are added to a membrane-catalyst layer assembly composed of the electrolyte membrane 51, the anode catalyst layer 61, and the cathode catalyst layer 71, to manufacture a cell 10. Then, the cells 10 and separators 20 are alternately stacked to form a cell stack 30. Thereafter, a power supply 40 is connected to the cell stack 30, to manufacture the water electrolysis device 1.

[0063] <4. Modifications> Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0064] In the above embodiment, the anode catalyst layer 61 contains two types of ionomers with different EW values. However, the anode catalyst layer 61 may contain three or more types of ionomers with different EW values. Also, the cathode catalyst layer 71 may contain two or more types of ionomers with different EW values.

[0065] In the above embodiment, the present invention is described as being applied to a PEM (Proton Exchange Membrane) type water electrolysis apparatus 1. However, the present invention may also be applied to water electrolysis apparatuses other than PEM type, such as AEM (Anion Exchange Membrane) type water electrolysis apparatuses. In AEM type water electrolysis apparatuses, for example, nickel (Ni), cobalt (Co), iron (Fe), or the like is used as a catalyst.

[0066] In the above embodiment, two types of ionomers with different EW values ​​are contained in the catalyst layer of the cell 10 used in the water electrolysis device 1. However, two types of ionomers with different EW values ​​may be contained in the catalyst layer of a cell used in a fuel cell using a similar method.

[0067] In addition, two types of ionomers with different EW values ​​may be included in the catalyst layer of a cell used in the LOHC (Liquid Organic Hydrogen Carrier) process, which produces organic hydrides (e.g., toluene-methylcyclohexane) by hydrogenating aromatic compounds such as toluene.

[0068] Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate or some may be deleted within the scope of not causing any contradiction. [Explanation of symbols]

[0069] 1: Water electrolysis device 10: Cell 20: Separator 30: Cell stack 40: Power supply 51: Electrolyte membrane 61: Anode catalyst layer 62: Porous transport layer 71: Cathode catalyst layer 72: Gas diffusion layer 80: Monomer 81: Main chain 82: Side chain 83: First ionomer 84: Second ionomer 90: Manufacturing equipment 91: Nozzle 92:Transport mechanism 93:Drying oven A1: 1st area A2:Second area

Claims

1. an electrolyte membrane; a catalyst layer formed on the surface of the electrolyte membrane; Equipped with The catalyst layer is a first ionomer; and a second ionomer having a higher EW value than the first ionomer; A membrane-catalyst layer assembly comprising:

2. The membrane-catalyst layer assembly according to claim 1, A membrane-catalyst layer assembly, wherein the weight ratio of the first ionomer in the catalyst layer is greater than the weight ratio of the second ionomer in the catalyst layer.

3. 3. The membrane-catalyst layer assembly according to claim 1 or 2, a side chain of the first ionomer and a side chain of the second ionomer have the same structure; a membrane-catalyst layer assembly, wherein the polymerization number of tetrafluoroethylene in the main chain of the second ionomer is greater than the polymerization number of tetrafluoroethylene in the main chain of the first ionomer;

4. 3. The membrane-catalyst layer assembly according to claim 1 or 2, A membrane-catalyst layer assembly, wherein the EW value of the second ionomer is greater than the EW value of the first ionomer by 100 [g / mol] or more.

5. The membrane-catalyst layer assembly according to claim 4, The EW value of the first ionomer is 900 [g / mol] or less, A membrane-catalyst layer assembly, wherein the EW value of the second ionomer is 1200 [g / mol] or more.

6. A water electrolysis device comprising the membrane catalyst layer assembly according to claim 1 or 2.

7. A method for producing a membrane catalyst-layer assembly, comprising: a first step of preparing a catalyst ink by mixing catalyst particles, a solvent, and an ionomer; a second step of applying the catalyst ink to a surface of an electrolyte membrane; a third step of drying the catalyst ink applied to the electrolyte membrane to form a catalyst layer; and The ionomer is a first ionomer; and a second ionomer having a higher EW value than the first ionomer; A manufacturing method comprising:

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