Water electrolysis membrane electrode and preparation method thereof and water electrolysis cell using the same

Abstract

To provide a water electrolysis membrane electrode that efficiently produces relatively dry hydrogen, a method for its preparation, and a water electrolysis cell using it.SOLUTION: The present invention discloses a water electrolysis membrane electrode that comprises a cathode gas diffusion layer, a cathode catalyst layer, an anion exchange membrane, a hydrophobic anode catalyst layer, and an anode gas diffusion layer, stacked in this order, wherein preparation raw materials for the hydrophobic anode catalyst layer include an anode catalyst, a hydrophobic material, and an anode ionomer, wherein the anode catalyst: hydrophobic material: anode ionomer are in a mass ratio of 10:1 to 3:1 to 3, and the porosity of the hydrophobic anode catalyst layer is 10 to 40%, and a preparation method thereof, and a water electrolysis cell using the same. According to the present invention, it is possible to reduce a switching frequency of a hydrogen dewatering device, reduce hydrogen production costs, and greatly promote scaling up of anion exchange membrane water electrolysis cells (AEMWE).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to the field of hydrogen production by water electrolysis, and more particularly to a water electrolysis membrane electrode, a method for preparing the same, and a water electrolysis cell using the same. [Background technology]

[0002] Anion exchange membrane water electrolysis (AEMWE) technology is a novel water electrolysis technology that uses an anion exchange membrane as a separator, and combines the low cost of alkaline water electrolysis technology with the advantages of proton exchange membrane water electrolysis (PEMWE) technology, such as faster response speed and higher current density. The membrane electrode, as the core component of AEMWE technology, is composed of a gas diffusion layer, a catalyst layer, and an anion exchange membrane, and is also the main site for hydrogen and oxygen generation.

[0003] However, commercially available AEMWE electrolyzers are unsuitable for producing relatively dry hydrogen gas because they circulate electrolyte between the cathode and anode sides. Furthermore, the need for a gas-liquid separation module on the cathode side and a water removal module for subsequent purification significantly increases hydrogen production costs. To obtain even drier hydrogen gas and reduce the cost of the hydrogen production system, AEMWE electrolyzers can be operated in anode-side feed circulation mode. The mechanism is that water molecules, the reactant, permeate from the anode side through an anion exchange membrane to the cathode side, where they participate in the hydrogen reduction reaction. This reduces the water content of the produced hydrogen gas, eliminating the need for gas-liquid separation equipment and lowering hydrogen production costs. However, because electrolyte is not circulated on the cathode side, a lack of water can cause changes in the wet / dry state of the separator, leading to membrane deformation and mechanical damage, reducing long-term stability. On the other hand, excessive water permeation prevents the production of relatively dry hydrogen gas. Therefore, with the aim of reducing the cost of hydrogen production, there is a demand for a water electrolysis membrane electrode that can efficiently produce dry hydrogen gas by applying anode feed circulation. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a water electrolysis membrane electrode, a method for preparing the same, and a water electrolysis cell using the same. A water electrolysis device that applies the anode-side feed liquid circulation of this water electrolysis membrane electrode can efficiently produce dry hydrogen gas, reduce the number of cathode gas-liquid separation modules, decrease the switching frequency of the hydrogen dewatering device, reduce hydrogen production costs, and significantly promote the scale-up of anion exchange membrane water electrolyzers (AEMWE). [Means for solving the problem]

[0005] According to a first aspect of the present invention, there is provided a water electrolysis membrane electrode comprising a cathode gas diffusion layer, a cathode catalyst layer, an anion exchange membrane, a hydrophobic anode catalyst layer, and an anode gas diffusion layer laminated in this order, wherein raw materials for preparing the hydrophobic anode catalyst layer include an anode catalyst, a hydrophobic material, and an anode ionomer, the mass ratio of anode catalyst:hydrophobic material:anode ionomer is 10:1 to 3:1 to 3, and the porosity of the hydrophobic anode catalyst layer is 10 to 40%.

[0006] Many commercially available AEM water electrolyzers use anode-cathode feed circulation. In this circulation mode, water molecules first receive electrons at the cathode side, undergoing a reduction reaction to generate hydroxide ions and hydrogen gas. The hydroxide ions then migrate to the anode side through the anion exchange membrane and participate in an oxygen-evolving reaction to generate water and oxygen gas. The high water molecule content at the cathode side introduces a large amount of water vapor into the hydrogen gas produced, affecting the purity of the hydrogen gas. This not only affects the purity of the hydrogen gas, but also requires the installation of a separate water removal module and frequent switching of the hydrogen water removal purification device, thereby increasing hydrogen production costs. In contrast, the water electrolysis membrane electrode provided by the present invention realizes an anode feed circulation mode, producing relatively dry hydrogen, reducing the switching frequency of the hydrogen water removal purification device, reducing hydrogen production costs, and significantly promoting the scale-up of anion exchange membrane water electrolyzers (AEMWEs). In the anode liquid supply circulation mode, raw water is first supplied to the anode side of the water electrolysis membrane electrode, and the amount of water molecules that permeate the catalyst layer is controlled by the hydrophobicity of the hydrophobic anode catalyst layer. Water molecules permeate from the anode catalyst layer through the anion exchange membrane to the cathode catalyst layer, where they participate in the hydrogen reduction reaction. By adjusting the amount of polytetrafluoroethylene charged in the hydrophobic anode catalyst layer, the amount of water molecules that permeates can be controlled, resulting in less water contained in the produced hydrogen gas.

[0007] The inventors discovered that when using the anode supply circulation mode, the transport of oxygen generated in a conventional anode catalyst layer in the electrolyte is slow, hindering mass transfer. Furthermore, water molecules must permeate from the anode gas diffusion layer through the anode catalyst layer to the cathode catalyst layer. When using the anode supply circulation mode with a conventional anode catalyst layer, the amount of water molecules permeating from the anode gas diffusion layer to the anode catalyst layer and then through the anion exchange membrane is too high, resulting in a high water content on the cathode side and a high water content in the hydrogen gas on the cathode side. Therefore, by adjusting and controlling the raw material composition ratio of the hydrophobic anode catalyst layer, the hydrophilic and hydrophobic properties of the hydrophobic anode catalyst layer can be balanced. By adjusting the porosity of the hydrophobic anode catalyst layer to 10-40%, the gas transmission rate can be accelerated, more active sites can be exposed, and the permeation of water molecules into the hydrophobic anode catalyst layer can be slowed. The anode ionomer not only functions as a binder in the hydrophobic anode catalyst layer, but also transports gas and dissolves OH. - If the hydrophobicity of the hydrophobic anode catalyst layer is too low, the oxygen transmission efficiency on the anode side will decrease and the water content on the cathode side will increase, making it easier for water molecules to be carried over into the produced hydrogen and increasing the cost of hydrogen production in the water electrolyzer.On the other hand, if the hydrophobicity of the hydrophobic anode catalyst layer is too high, fewer water molecules will remain on the cathode side, affecting ion conduction and being disadvantageous for highly efficient and long-term stable hydrogen production.

[0008] The hydrophobic anode catalyst layer preferably has a contact angle of greater than 90°.

[0009] The hydrophobic material preferably includes at least one of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and perfluoroethylene propene copolymer (FEP). Preferably, the hydrophobic material comprises polytetrafluoroethylene.

[0010] As raw materials for preparing the hydrophobic anode catalyst layer, the mass ratio of anode catalyst:polytetrafluoroethylene:anode ionomer is more preferably 10:1.5:1.5.

[0011] The anode ionomer includes at least one of Alkymer ionomer, Fumasep ionomer, Ionomr ionomer, Versogen ionomer, and Sustainion ionomer. More preferably, the ionomer includes Alkymer ionomer.

[0012] The hydrophobic anode catalyst layer preferably has a porosity of 20 to 30%. When the porosity of the hydrophobic anode catalyst layer is 20 to 30%, the number of catalytically active sites in the hydrophobic anode catalyst layer increases, and generated oxygen bubbles are quickly expelled, improving oxygen transport efficiency and stabilizing the structure of the hydrophobic anode catalyst layer, thereby mitigating structural collapse of the catalyst layer and extending the stable operating time of the water electrolysis equipment.

[0013] A preferred method for preparing a hydrophobic anode catalyst layer involves mixing raw materials for preparing the hydrophobic anode catalyst layer to form an anode catalyst layer slurry, coating the slurry on one side of an anode gas diffusion layer, and firing the slurry at a temperature of 300 to 500°C. Because polytetrafluoroethylene must be melted and dispersed in the catalyst layer under high-temperature conditions, when preparing a hydrophobic anode catalyst layer using the catalyst coated substrate (CCS) method, the ratio of polytetrafluoroethylene to anode catalyst in the catalyst layer actually produced is adjusted to a ratio close to a preset ratio during preparation, thereby achieving adjustment and control of the hydrophobicity and pore structure of the catalyst layer and promoting oxygen transmission. Here, the CCS method refers to a method in which a catalytically active component is first coated on the surface of a gas diffusion layer to form a catalyst layer, and then the catalyst layer is attached to an anion exchange membrane to form a water electrolysis membrane electrode.

[0014] When preparing the hydrophobic anode catalyst layer, the temperature rise rate is preferably 5° C. / min.

[0015] When preparing the hydrophobic anode catalyst layer, it is more preferable that the temperature be kept at 350° C. for 30 minutes.

[0016] The anode catalyst layer slurry is preferably kept warm under an atmosphere of an inert gas, such as nitrogen, argon, or helium, and more preferably nitrogen.

[0017] In the anode catalyst layer slurry, the concentration of the anode catalyst is preferably 10 to 30 mg / mL, and more preferably 20 mg / mL.

[0018] The raw materials for preparing the hydrophobic anode catalyst layer preferably further contain a solvent containing ethanol and / or water, and more preferably the solvent is a mixed solution of ethanol and water, with the volume ratio of ethanol to water being 1:1.

[0019] The hydrophobic anode catalyst layer has an anode catalyst loading of 1 to 10 mg / cm 2 and the anode catalyst is selected from the group consisting of iridium (IV) oxide (IrO2), ruthenium dioxide (RuO2), nickel-iron layered double hydroxide (NiFe LDH), nickel-iron oxide (NiFeO x ), nickel-iron alloy, and nickel-iron-cobalt alloy. By adjusting the amount of the anode catalyst loaded, the content of the hydrophobic material in the catalyst layer can be adjusted, and the hydrophobicity of the hydrophobic anode catalyst layer can be adjusted. When the amount of the anode catalyst loaded is within the above range, the resulting hydrophobic anode catalyst layer has excellent catalytic performance.

[0020] It is preferable to use a nickel-iron layered double hydroxide as the anode catalyst.

[0021] The hydrophobic anode catalyst layer has an anode catalyst loading of 5 mg / cm 2 It is more preferable that:

[0022] The raw materials for preparing the cathode catalyst layer preferably include a cathode catalyst, a hydrophilic carbon material, and a cathode ionomer, with the mass ratio of cathode catalyst:hydrophilic carbon material:cathode ionomer being 8:2 to 6:1 to 5. By incorporating a hydrophilic carbon material into the cathode catalyst layer and adjusting the ratio of the hydrophilic carbon material to the cathode catalyst, the hydrophilicity and water retention of the cathode catalyst layer can be improved, sufficient water, a reactant on the cathode side, improve the structural stability of the catalyst layer during operation of the water electrolysis membrane electrode, and reduce the water content in the hydrogen gas. Combining this hydrophilic cathode catalyst layer with a hydrophobic anode catalyst layer makes it possible to control the amount of water molecules passing from the anode side to the cathode side, achieving an anode liquid supply circulation mode in the water electrolysis cell and advantageously reducing the water content in the hydrogen gas.

[0023] As raw materials for preparing the cathode catalyst layer, the mass ratio of cathode catalyst:hydrophilic carbon material:cathode ionomer is more preferably 8:4:2.

[0024] The cathode ionomer includes at least one of Alkymer ionomer, Fumasep ionomer, Ionomr ionomer, Versogen ionomer, and Sustainion ionomer. More preferably, the ionomer includes Alkymer ionomer.

[0025] The hydrophilic carbon material preferably includes at least one of a carboxylated carbon material and an aminated carbon material. For example, the hydrophilic carbon material may be at least one of a carboxylated carbon nanotube, a carboxylated graphene, a carboxylated carbon black, a carboxylated carbon balloon, a carboxylated carbon fiber, a hydroxylated carbon nanotube, a hydroxylated graphene, a hydroxylated carbon black, a hydroxylated carbon balloon, a hydroxylated carbon fiber, an aminated carbon nanotube, an aminated graphene, an aminated carbon black, an aminated carbon balloon, and an aminated carbon fiber.

[0026] The hydrophilic carbon material preferably includes a carboxylated carbon material. Carboxylated carbon materials not only have stronger hydrophilicity than other hydrophilic groups, but also retain water molecules that have permeated to the cathode side, ensuring the moisture content of the cathode catalyst layer and the anion exchange membrane, reducing the likelihood of swelling or shrinkage of the membrane layer, and preventing alternation between wet and dry states during circulation, which can affect the electrochemical performance and stability of the water electrolysis cell. Furthermore, incorporating a carboxylated carbon material into the cathode catalyst layer can improve the adhesion between the cathode catalyst layer and the anion exchange membrane, and the conductive properties of the carboxylated carbon material can be utilized to improve the stability and electrochemical performance of the water electrolysis membrane electrode.

[0027] The hydrophilic carbon material preferably includes carboxylated carbon nanotubes. Carboxylated carbon nanotubes have high electrical conductivity and can reduce ohmic impedance. Therefore, when carboxylated carbon nanotubes are selected as the hydrophilic carbon material, the ohmic impedance of the cathode catalyst layer can be reduced, improving the performance of the catalyst layer. Furthermore, since carboxylated carbon nanotubes are one-dimensional materials, they can be bonded to the cathode ionomer and cathode catalyst to form a three-dimensional network structure during the preparation of the cathode catalyst layer, thereby adjusting the hydrophilicity and pore structure of the cathode catalyst layer and enhancing the catalytic effect of the cathode catalyst layer.

[0028] A preferred method for preparing a cathode catalyst layer includes uniformly mixing raw materials for preparing the cathode catalyst layer to form a cathode catalyst layer slurry, which is then coated on one side of an anion exchange membrane. When the cathode catalyst layer is prepared by the catalyst coated membrane (CCM) method using an anion exchange membrane as a support substrate, the contact resistance between the cathode catalyst layer and the anion exchange membrane is reduced, improving the electrochemical performance of the water electrolysis membrane electrode. The CCM method involves first coating the surface of an anion exchange membrane with catalytically active components to form a catalyst layer, and then adhering the catalyst layer to a gas diffusion layer to form a water electrolysis membrane electrode.

[0029] When preparing the cathode catalyst layer slurry, the cathode catalyst layer slurry is mixed uniformly by high-speed shearing, preferably at a shear rate of 500 to 20,000 rpm, for a mixing time of 10 to 90 minutes, and at a shearing temperature of less than 5° C. More preferably, the shear rate is 10,000 rpm, and the mixing time is 30 minutes.

[0030] When preparing the cathode catalyst layer slurry, the raw materials for preparing the cathode catalyst layer are uniformly mixed by ultrasonic dispersion, preferably at an ultrasonic power of 50 to 150 W for a time of 10 to 90 minutes, more preferably at an ultrasonic power of 100 W for 30 minutes.

[0031] The cathode catalyst layer slurry coating method preferably includes painting, spraying or screen printing.

[0032] In the cathode catalyst layer slurry, the concentration of the cathode catalyst is preferably 10 to 30 mg / mL, and more preferably 20 mg / mL.

[0033] The raw materials for preparing the cathode catalyst layer preferably further contain a solvent containing ethanol and / or water, more preferably a mixed solution of ethanol and water, with the volume ratio of ethanol to water being 1:1.

[0034] The cathode catalyst layer has a cathode catalyst loading of 1 to 10 mg / cm 2 and the cathode catalyst preferably contains at least one of a platinum-carbon catalyst (Pt / C), a nickel-phosphorus catalyst (NiP), a nickel-molybdenum alloy (NiMo alloy), a nickel-manganese alloy (NiMn alloy), a nickel-molybdenum oxide (NiMo oxide), a nickel-manganese oxide (NiMn oxide), and molybdenum disulfide (MoS2).

[0035] Molybdenum disulfide was used as the cathode catalyst, and the amount of the cathode catalyst supported in the cathode catalyst layer was 5 mg / cm. 2 It is preferable to set the following.

[0036] The thickness of the anion exchange membrane is preferably 20 to 100 μm, and more preferably 75 μm.

[0037] A second aspect of the present invention provides a method for preparing the water electrolysis membrane electrode, which comprises laminating a cathode gas diffusion layer, a cathode catalyst layer, an anion exchange membrane, a hydrophobic anode catalyst layer, and an anode gas diffusion layer in this order, and hot pressing the resulting mixture at a temperature of 50 to 150°C under a pressure of 100 to 600 psi.

[0038] According to a third aspect of the present invention, there is provided a water electrolysis cell including the above-mentioned water electrolysis membrane electrode. The water electrolysis cell provided by the present invention is equipped with the above-mentioned water electrolysis membrane electrode, which makes it possible to efficiently produce dry hydrogen, optimize the post-treatment process of hydrogen production, and reduce the cost of hydrogen production, and is therefore expected to bring about a breakthrough in large-scale hydrogen production through the electrolysis of renewable energy. DETAILED DESCRIPTION OF THE INVENTION

[0039] In order to allow those skilled in the art to better understand the present invention, the present invention will be clearly and completely described below based on examples. It is clear that the examples described herein are not all of the examples of the present invention, but are merely considered to be some examples. Other examples that can be made by those skilled in the art based on the examples of the present invention without any inventive ideas are all encompassed within the technical scope of the present application.

[0040] Example 1 (1) Preparation of hydrophobic anode catalyst layer The raw materials used to prepare the hydrophobic anode catalyst layer were anode catalyst, polytetrafluoroethylene, anode ionomer, and solvent. The anode catalyst was nickel-iron layered double hydroxide (NiFe LDH), the anode ionomer was Alkymer ionomer, and the solvent was a mixed solution of ethanol and water with a volume ratio of ethanol to water of 1:1. The mass ratio of anode catalyst:polytetrafluoroethylene:anode ionomer was 10:1.5:1.5.

[0041] The preparation method of the hydrophobic anode catalyst layer includes the following process. The raw materials for preparing the hydrophobic anode catalyst layer were mixed uniformly to prepare anode catalyst layer slurry. The amount of solvent added was adjusted so that the anode catalyst concentration in the anode catalyst layer slurry was 20 mg / mL. The anode catalyst layer slurry was then coated on one side of the anode gas diffusion layer, and the temperature was raised at a rate of 5°C / min in a nitrogen atmosphere and maintained at 350°C for 30 minutes to prepare a hydrophobic anode catalyst layer. The anode catalyst loading was 5 mg / cm. 2 It was.

[0042] (2) Preparation of the cathode catalyst layer The cathode catalyst layer was prepared using a cathode catalyst, a hydrophilic carbon material, a cathode ionomer, and a solvent. The cathode catalyst was a molybdenum disulfide catalyst, the hydrophilic carbon material was carboxylated carbon nanotubes, the cathode ionomer was Alkymer ionomer, and the solvent was a mixed solution of ethanol and water, with a volume ratio of ethanol to water of 1:1. The mass ratio of the cathode catalyst:hydrophilic carbon material:cathode ionomer was 8:4:2 (i.e., 4:2:1).

[0043] The method for preparing the cathode catalyst layer includes the following process. First, the cathode catalyst, hydrophilic carbon material, cathode ionomer, and solvent were uniformly mixed by high-speed shearing at a shear rate of 10,000 rpm for 30 minutes at a temperature of less than 5° C. Next, ultrasonic power was set to 100 W for 30 minutes. Next, the cathode catalyst layer slurry was coated on one side of the anion exchange membrane to prepare a cathode catalyst layer. The cathode catalyst layer thus obtained had a cathode catalyst loading of 5 mg / cm. 2 It was.

[0044] (3) Preparation of water electrolysis membrane electrodes The water electrolysis membrane electrode was composed of a cathode gas diffusion layer, the cathode catalyst layer, an anion exchange membrane, the hydrophobic anode catalyst layer, and an anode gas diffusion layer, laminated in this order. The anion exchange membrane had a thickness of 75 μm.

[0045] The water electrolysis membrane electrode was prepared by stacking a cathode gas diffusion layer, a cathode catalyst layer, an anion exchange membrane, a hydrophobic anode catalyst layer, and an anode gas diffusion layer in this order, followed by hot pressing at a pressure of 300 psi at a hot pressing temperature of 100°C for 15 minutes.

[0046] Example 2 In this example, a water electrolysis membrane electrode was prepared in exactly the same manner as in Example 1, with reference to the preparation method provided in Example 1. The amount of polytetrafluoroethylene charged when preparing the hydrophobic anode catalyst layer was adjusted so that the mass ratio of the anode catalyst to polytetrafluoroethylene to the anode ionomer was 10:1:1.5. The blending ratios of the other raw materials and the preparation method were the same as in Example 1.

[0047] Example 3 In this example, a water electrolysis membrane electrode was prepared in exactly the same manner as in Example 1, with reference to the preparation method provided in Example 1. The amount of polytetrafluoroethylene charged when preparing the hydrophobic anode catalyst layer was adjusted so that the mass ratio of the anode catalyst to polytetrafluoroethylene to the anode ionomer was 10:3:1.5. The blending ratios of the other raw materials and the preparation method were the same as in Example 1.

[0048] Example 4 In this example, a water electrolysis membrane electrode was prepared in exactly the same manner as in Example 1, with reference to the preparation method provided in Example 1. The amount of anode ionomer added when preparing a hydrophobic anode catalyst layer was adjusted so that the mass ratio of anode catalyst to polytetrafluoroethylene to anode ionomer was 10:1.5:1. The blending ratios of the other raw materials and the preparation method were the same as in Example 1.

[0049] Example 5 In this example, a water electrolysis membrane electrode was prepared in exactly the same manner as in Example 1, with reference to the preparation method provided in Example 1. The amount of anode ionomer added when preparing a hydrophobic anode catalyst layer was adjusted so that the mass ratio of anode catalyst to polytetrafluoroethylene to anode ionomer was 10:1.5:3. The blending ratios of the other raw materials and the preparation method were the same as in Example 1.

[0050] Example 6 In this example, a water electrolysis membrane electrode was prepared in exactly the same manner as in Example 1, with reference to the preparation method provided in Example 1, except that the same mass of perfluoroethylene propene copolymer (FEP) emulsion was used instead of the polytetrafluoroethylene used in Example 1 when preparing the hydrophobic anode catalyst layer.

[0051] Example 7 In this example, a water electrolysis membrane electrode was prepared by referring to the preparation method provided in Example 1, with the blending ratios of the other raw materials and the preparation method being exactly the same as in Example 1, except that no hydrophilic carbon material was added when preparing the cathode catalyst layer.

[0052] Example 8 In this example, a water electrolysis membrane electrode was prepared in exactly the same manner as in Example 1, with reference to the preparation method provided in Example 1, except that the amounts of the hydrophilic carbon material and the cathode ionomer charged when preparing the cathode catalyst layer were adjusted so that the mass ratio of the cathode catalyst to the hydrophilic carbon material to the cathode ionomer was 8:2:5. The blending ratios of the other raw materials and the preparation method were the same as in Example 1.

[0053] Example 9 In this example, with reference to the preparation method provided in Example 1, a water electrolysis membrane electrode was prepared in exactly the same manner as in Example 1 in the blending ratio of the other raw materials and the preparation method, except that the amounts of the hydrophilic carbon material and the cathode ionomer charged when preparing the cathode catalyst layer were adjusted so that the mass ratio of the cathode catalyst to the hydrophilic carbon material to the cathode ionomer was 8:6:1.

[0054] Example 10 In this example, a water electrolysis membrane electrode was prepared in exactly the same manner as in Example 1, with reference to the preparation method provided in Example 1, except that the same mass of carboxylated carbon black was used instead of the carboxylated carbon nanotubes used in Example 1 when preparing a cathode catalyst layer. The blending ratios of the other raw materials and the preparation method were the same as in Example 1.

[0055] Comparative Example 1 In this comparative example, a water electrolysis membrane electrode was provided, which was composed of a cathode gas diffusion layer, a cathode catalyst layer, an anion exchange membrane, an anode catalyst layer, and an anode gas diffusion layer laminated in this order. (1) Preparation of cathode catalyst layer: The cathode catalyst layer preparation method provided in Example 1 was used with reference to the method. Except for not adding a hydrophilic carbon material to the preparation raw materials, the blending ratio of the other raw materials and the preparation method were exactly the same as in Example 1. (2) Preparation of anode catalyst layer: With reference to the preparation method for the hydrophobic anode catalyst layer provided in Example 1, the blending ratio of the other raw materials and the preparation method were exactly the same as in Example 1, except that polytetrafluoroethylene, a hydrophobic material, was not added to the preparation raw materials. (3) Preparation of water electrolysis membrane electrode: exactly the same as in Example 1.

[0056] Comparative Example 2 In this comparative example, a water electrolysis membrane electrode was prepared in exactly the same manner as in Example 1, with reference to the preparation method provided in Example 1, except that polytetrafluoroethylene, a hydrophobic material, was not added when preparing the anode catalyst layer. The blending ratios of the other raw materials and the preparation method were the same as in Example 1.

[0057] Comparative Example 3 In this comparative example, a water electrolysis membrane electrode was prepared in exactly the same manner as in Example 1, with reference to the preparation method provided in Example 1, except that the amount of polytetrafluoroethylene, a hydrophobic material, charged when preparing the hydrophobic anode catalyst layer was adjusted so that the mass ratio of the anode catalyst to polytetrafluoroethylene to the anode ionomer was 10:0.5:4. The blending ratios of the other raw materials and the preparation method were the same as in Example 1.

[0058] Comparative Example 4 In this comparative example, a water electrolysis membrane electrode was prepared in exactly the same manner as in Example 1, with reference to the preparation method provided in Example 1, except that the amount of polytetrafluoroethylene charged when preparing the hydrophobic anode catalyst layer was adjusted so that the mass ratio of the anode catalyst to polytetrafluoroethylene to the anode ionomer was 10:4:1.5. The blending ratios of the other raw materials and the preparation method were the same as in Example 1.

[0059] Measurement example Subjects to be tested: Water electrolysis cells were assembled using each of the water electrolysis membrane electrodes prepared in Examples 1 to 10 and Comparative Examples 1 to 4, together with a cathode-side electrode plate (with flow field), an anode-side electrode plate (with flow field), an end plate, and an insulating plate.

[0060] Measurement items and methods:

[0061] (1) Porosity: The anode catalyst layer of the water electrolysis membrane electrode was peeled off with tape, and the porosity of the anode catalyst layer was measured in accordance with the test method of "GB / T21650.1-2008 Measurement of Pore Size Distribution and Porosity of Solid Materials by Mercury Intrusion and Gas Adsorption Methods, Part 1: Mercury Intrusion Method." In this measurement example, a porosity of 10 to 40% was considered acceptable, and a porosity of 20 to 30% was considered good.

[0062] (2) Ohmic impedance: Using an electrochemical workstation, the working electrode WE and working sensor electrode WS were connected to the cathode electrode, and the reference electrode RE and auxiliary electrode WS were connected to the anode electrode. The constant-voltage AC impedance of the test object was measured at rest potential with a high frequency of 10,000 Hz, a low frequency of 1 Hz, and an amplitude of 10 mV. The measurement results were fitted and the ohmic impedance (HFR) values ​​were recorded.

[0063] (3) Water electrolysis performance of the electrolytic cell: Using an electrochemical workstation, the working electrode WE and working sensor electrode WS were connected to the cathode side electrode plate, and the reference electrode RE and auxiliary electrode wire were connected to the anode side electrode plate. The constant current test method was used to measure the water electrolysis performance of the electrolytic cell. 2 The current was set to 10 stages, and measurements were taken for 10 seconds at each stage. The voltage value was recorded every second, and the average voltage at each current stage was recorded.

[0064] (4) Moisture content: Refer to the test method of "GB / T5832.2-2016 Gas Analysis Trace Moisture Measurement Part 2: Dew Point Method" and after the test object is operating stably, the generated hydrogen gas is collected and the moisture content test is performed, and the dew point temperature of the hydrogen gas is recorded. In this measurement example, the dew point temperature of the hydrogen gas is (0°C, 1 bar, absolute humidity 4 g / m 3 If the temperature was below -2.5°C, it was considered a pass.

[0065] Measurement results: The raw material composition of the test subject and the measurement results in this test example are shown in Tables 1 and 2.

[0066] Table 1. Raw material composition of the test subject in this test example JPEG2025179788000001.jpg142116

[0067] Table 2. Measurement results of test subjects in this test example JPEG2025179788000002.jpg81115

[0068] Result analysis: Comparing the performance indexes in Table 2 between Examples 1 to 10 and Comparative Examples 1 to 4, it can be seen that, compared to the water electrolytic cells of Comparative Examples 1 to 4, the water electrolytic cells prepared using the membrane electrodes of Examples 1 to 10 further utilize the water retention effect of the cathode catalyst layer by adjusting the hydrophilicity / hydrophobicity and porosity of the anode catalyst layer in the membrane electrodes of Examples 1 to 10, resulting in faster gas diffusion, higher ion conduction efficiency, lower water electrolytic cell pressure, and less water content in the obtained hydrogen gas.

[0069] Comparing the performance indexes in Table 2 between Example 1 and Comparative Examples 1 and 2, which were set based on Example 1, it can be seen that the water electrolytic cell provided in Example 1 has a lower ohmic impedance and the water content of the produced hydrogen gas is also lower. This shows that a water electrolysis membrane electrode using a hydrophobic anode catalyst layer can promote gas conduction and ion transfer, reduce ohmic impedance, and provide a low water electrolysis cell pressure, as well as improve the purity of hydrogen gas and reduce the water content in the hydrogen gas.

[0070] Comparing the performance indicators in Table 2 between Examples 1 to 5 and Comparative Examples 3 and 4 reveals that as the proportion of hydrophobic material and / or the proportion of anode ionomer in the hydrophobic anode catalyst layer increases, the porosity and hydrophobicity of the catalyst layer are adjusted, resulting in a corresponding increase in ohmic impedance and a corresponding increase in the cell pressure of the water electrolyzer. The porosity of the hydrophobic anode catalyst layer can be adjusted by adjusting the blending ratio of the raw materials in the hydrophobic anode catalyst layer. When the mass ratio of anode catalyst to hydrophobic material to anode ionomer in the hydrophobic anode catalyst layer is within the range of 10:1 to 3:1 to 3, the hydrophobic anode catalyst layer has appropriate porosity and hydrophilicity / hydrophobicity, the water electrolyzer exhibits good water electrolysis performance, and the produced hydrogen gas has high purity and low water content. Here, the water electrolyzer exhibits good overall performance when the porosity of the hydrophobic anode catalyst layer is in the range of 10 to 40%, and exhibits lower ohmic impedance when the porosity of the hydrophobic anode catalyst layer is in the range of 20 to 30%.

[0071] Comparing the overall performance of Example 1 and Example 7, it can be seen that the ohmic impedance obtained in Example 1 was lower than that obtained in Example 7. This is because, in Example 1, the hydrophilic cathode catalyst layer was combined with the hydrophobic anode catalyst layer, making it possible to control the amount of water molecules permeating from the anode side to the cathode side. This achieves an anode liquid feed circulation mode in the water electrolyzer, maintains the moisture content of the membrane electrode, increases ion transport efficiency, improves electrolysis efficiency, and contributes to generating drier hydrogen.

[0072] The above examples are not intended to limit the technical scope of the present invention, but merely to illustrate the technical solutions of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art can understand that modifications and equivalent substitutions can be made to the present invention without departing from the spirit and scope of the present invention.

Claims

1. a water electrolysis membrane electrode comprising a cathode gas diffusion layer, a cathode catalyst layer, an anion exchange membrane, a hydrophobic anode catalyst layer, and an anode gas diffusion layer laminated in this order; a water electrolysis membrane electrode, wherein raw materials for preparing the hydrophobic anode catalyst layer include an anode catalyst, a hydrophobic material, and an anode ionomer, the mass ratio of the anode catalyst:the hydrophobic material:the anode ionomer is 10:1 to 3:1 to 3, and the porosity of the hydrophobic anode catalyst layer is 10 to 40%.

2. 2. The water electrolysis membrane electrode according to claim 1, wherein the hydrophobic material comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride, and perfluoroethylene propene copolymer.

3. 2. The water electrolysis membrane electrode according to claim 1, wherein the porosity of the hydrophobic anode catalyst layer is 20 to 30%.

4. 2. The water electrolysis membrane electrode according to claim 1, wherein the method for producing the hydrophobic anode catalyst layer comprises: coating one side of the anode gas diffusion layer with an anode catalyst layer slurry obtained by mixing raw materials for preparing the hydrophobic anode catalyst layer; and firing the resulting mixture at a temperature of 300 to 500°C.

5. The hydrophobic anode catalyst layer has a supporting amount of the anode catalyst of 1 to 10 mg / cm ２ and the anode catalyst contains at least one of iridium(IV) oxide, ruthenium dioxide, nickel-iron layered double hydroxide, nickel-iron oxide, nickel-iron alloy, and nickel-iron-cobalt alloy.

6. 2. The water electrolysis membrane electrode according to claim 1, wherein raw materials for preparing the cathode catalyst layer include a cathode catalyst, a hydrophilic carbon material, and a cathode ionomer, and the mass ratio of the cathode catalyst:the hydrophilic carbon material:the cathode ionomer is 8:2 to 6:1 to 5.

7. 7. The water electrolysis membrane electrode according to claim 6, wherein the hydrophilic carbon material comprises at least one of a carboxylated carbon material and an aminated carbon material.

8. The cathode catalyst layer has a cathode catalyst loading of 1 to 10 mg / cm ２ and the cathode catalyst comprises at least one of a platinum-carbon catalyst, a nickel-phosphorus catalyst, a nickel-molybdenum alloy, a nickel-manganese alloy, a nickel-molybdenum oxide, a nickel-manganese oxide, and molybdenum disulfide.

9. A method for preparing the water electrolysis membrane electrode according to any one of claims 1 to 8, comprising the steps of: the cathode gas diffusion layer, the cathode catalyst layer, the anion exchange membrane, the hydrophobic anode catalyst layer, and the anode gas diffusion layer are laminated in this order, and hot-pressed at a pressure of 100 to 600 psi at a hot-pressing temperature of 50 to 150°C.

10. A water electrolysis cell comprising the water electrolysis membrane electrode according to any one of claims 1 to 8.

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