Membrane electrode, preparation method thereof, electrochemical device and water electrolysis hydrogen production method

Abstract

The invention provides a membrane electrode, a preparation method thereof, an electrochemical device and a water electrolysis hydrogen production method. The membrane electrode comprises a cathode catalyst layer, a proton exchange membrane and an anode catalyst layer which are sequentially stacked, the anode catalyst layer is formed by anode catalyst slurry; the preparation method of the anode catalyst slurry comprises the following steps: mixing an anode catalyst, resin and a solvent to obtain a first intermediate solution; adding a first pore-forming agent into the first intermediate solution, and stirring to obtain anode catalyst slurry; the first pore-forming agent comprises a carbon material, the stirring rotating speed is smaller than or equal to 1000 revolutions per minute, and the stirring time is smaller than or equal to 30 minutes. The invention also provides a preparation method of the membrane electrode, an electrochemical device comprising the membrane electrode and a method for producing hydrogen by electrolyzing water. The catalyst layer slurry of the membrane electrode contains the pore-forming agent, so that the catalyst loss caused by the pore-forming agent removal process can be avoided while the catalyst layer has a porous structure, and the catalytic performance and durability of the membrane electrode are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of proton exchange membrane water electrolysis technology, and in particular to a membrane electrode and a preparation method thereof, an electrochemical device and a method for producing hydrogen by electrolysis of water. Background Art

[0002] With the advancement of science and technology, low-carbon, clean, and environmentally friendly hydrogen energy technologies (such as fuel cells and water electrolysis) are considered one of the most promising solutions for reducing dependence on fossil fuels, providing clean energy, and further achieving sustainable energy development. They have become a hot topic of research. Proton exchange membrane water electrolysis (PEMWE) can directly use electricity to decompose water molecules into hydrogen and oxygen through an electrocatalytic reaction. Compared to traditional alkaline electrolyzers, PEMWE offers advantages such as high energy conversion efficiency, rapid low-temperature startup, and zero pollution. It is widely considered to have broad application prospects in hydrogen energy storage, hydrogen smelting, aerospace, and other fields.

[0003] The electrolyzer is a key component of PEMWE, consisting of a membrane electrode (MEA), a diffusion layer (also called a current collector), and electrode plates. The diffusion layer (also called a current collector) primarily serves as a conductor and gas diffuser, transferring current to the catalyst on the membrane electrode surface while allowing gases generated by the anode and cathode to diffuse out quickly. The electrode plates separate each electrolytic cell and must also exhibit good conductivity and corrosion resistance. The membrane electrode consists of an anode catalyst, a proton exchange membrane, and a cathode catalyst. Traditional membrane electrode fabrication processes include CCM and CCS. The CCM method involves directly coating the catalyst onto the proton exchange membrane through electrochemical deposition, spraying, or printing, or by first spraying the catalyst onto a substrate and then transferring it to the proton exchange membrane through transfer printing, ultimately forming a three-layer membrane electrode structure: catalyst-proton membrane-catalyst. The CCS method involves loading the catalyst onto the gas diffusion layer and then hot-pressing it onto the proton exchange membrane to form the membrane electrode. The CCM process can improve catalyst utilization and form a stable interface structure. The bonding force between the catalyst and the proton membrane is enhanced and not easy to fall off. The interface resistance is low, and it can operate stably for a long time at a lower voltage. The ohmic loss between the catalytic layer and the proton membrane is also attenuated, thereby obtaining a higher current density.

[0004] The stability of a membrane electrode (MEA) is one of its most important performance indicators and is determined by the catalytic layer on the surface of the MEA. The catalytic layer, primarily composed of electrocatalysts, proton-conducting ionomers, and a pore structure, is the core site for electrochemical reactions involving multiphase mass transfer and energy conversion.

[0005] The structure and properties of the catalytic layer have a significant impact on the activation polarization, concentration polarization, and ohmic polarization of the electrochemical reaction. The amount and distribution of perfluorosulfonic acid resin ionomers, which act as proton conductors and binders in the catalytic layer, cannot be ignored in their impact on electrolytic performance. Too little ionomer will lead to a decrease in the proton conductivity of the catalytic layer, while too much ionomer will occupy too much volume in the catalytic layer, reducing pore patency, increasing gas transmission resistance, and leading to a decrease in conductivity within the catalytic layer and an increase in the contact resistance between the catalytic layer and the diffusion layer. It can even cause the catalytic layer to tear due to the formation of tiny bubbles due to gas accumulation, leading to partial peeling of the catalytic layer after long-term operation and reduced durability.

[0006] In the existing technology, pore-forming agents can be used to form a porous structure in the catalyst layer. However, the existing pore-forming methods have the following problems: the existing technology requires removing the pore-forming agent to form a porous structure, but the process of removing the pore-forming agent will cause the catalytic layer structure to be destroyed; the pore-forming agent cannot be fully removed, and the residual pore-forming agent will affect the catalyst performance; the pore-forming agent removal time is too long, resulting in continuous loss of catalyst and reduced membrane electrode stability.

[0007] Therefore, in order to solve the problem of insufficient pore patency in the catalytic layer of the water electrolysis membrane electrode, which leads to obstruction of material transfer and thus affects the performance and durability of the catalytic layer, it is necessary to provide a design and development method for the catalytic layer that comprehensively considers the three-phase reaction of proton, electron and material transfer, the matching, compatibility and durability of various materials, so as to improve the catalytic performance and durability of the membrane electrode by preparing a porous catalytic layer without changing the existing anode catalyst. Summary of the Invention

[0008] To address the above-mentioned issues, the present invention provides a membrane electrode, a method for preparing the same, an electrochemical device, and a method for producing hydrogen by electrolysis. The membrane electrode's catalyst layer slurry contains a pore-forming agent, which not only creates a porous structure in the catalyst layer but also prevents catalyst loss during pore-forming agent removal, thereby improving the membrane electrode's catalytic performance and durability.

[0009] In order to achieve the above object, the present invention provides a membrane electrode, which comprises a cathode catalyst layer, a proton exchange membrane, and an anode catalyst layer stacked in sequence;

[0010] Wherein, the anode catalyst layer is formed by anode catalyst slurry;

[0011] The preparation method of the anode catalyst slurry includes: mixing an anode catalyst, a resin, and a solvent to obtain a first intermediate solution; adding a first pore-forming agent to the first intermediate solution and stirring to obtain an anode catalyst slurry; wherein the first pore-forming agent includes a carbon material, the stirring speed is less than or equal to 1000 rpm, and the stirring time is less than or equal to 30 minutes.

[0012] In the above-mentioned anode catalyst layer, the anode catalyst includes Ir black and / or IrOx (iridium oxide, 1≤x≤2), and the slurry formed thereby is a PEMWE anode catalyst slurry.

[0013] In the above-mentioned anode catalyst layer, when the anode catalyst includes both Ir black and IrOx, the mass ratio of Ir black to IrOx is generally 1:3-3:1, that is, the anode catalyst may include Ir black and IrOx in a mass ratio of 1:3-3:1.

[0014] In the above-mentioned anode catalyst layer, the mass content of the anode catalyst in the anode catalyst layer is 0.5-5.0 mg / cm 2 .

[0015] In the anode catalyst slurry, the anode catalyst content in the anode catalyst slurry is 1%-20% by mass, for example, 1%, 2%, 3%, 4%, 5%, 10%, 12%, 15%, 20%, and other specific values, as well as ranges with any two of the above specific values as endpoints. The anode catalyst content in the anode catalyst slurry can further be 5%-15% by mass.

[0016] In the above anode catalyst slurry, the resin includes perfluorosulfonic acid resin.

[0017] In the above anode catalyst slurry, the kinetic diameter of the resin in the anode catalyst slurry is generally 100-1000 nm.

[0018] In the anode catalyst slurry, the mass ratio of the resin to the anode catalyst is 2:10-10:10, and can be specifically 2:10, 3:10, 4:10, 5:10, 6:10, 7:10, 8:10, 9:10, 10:10, or a range having any two of the above values as endpoints. The mass ratio of the resin to the anode catalyst can further be 2:10-5:10.

[0019] In the above-mentioned anode catalyst slurry, the solvent includes water and / or alcohol. The alcohol may include one or a combination of two or more of ethanol, isopropanol, n-propanol, and propylene glycol. In some specific embodiments, when the solvent includes water and alcohol, the mass ratio of the water to alcohol is 1:9-9:1, and further may be 3:7-8:2.

[0020] In the anode catalyst slurry, the mixing process of the anode catalyst, resin, and solvent includes mixing and uniformly dispersing the anode catalyst, resin, and solvent to obtain a first intermediate solution. This mixing and uniform dispersion process can improve the dispersion of the nanosized anode catalyst and facilitate sufficient contact between the anode catalyst and the resin. More specifically, the mixing process of the anode catalyst, resin, and solvent can include ultrasonicating and / or ball-milling the mixture to obtain the first intermediate solution. Specifically, the mixture can be subjected to either ultrasonic treatment or ball milling alone, or a combination of both treatments.

[0021] In the above preparation method, the ultrasonic treatment and ball milling treatment can fully disperse the anode catalyst (nanosized) so that the anode catalyst is fully in contact with the resin. In some specific embodiments, the ultrasonic treatment and ball milling treatment can be performed sequentially, wherein the ultrasonic treatment can disperse the anode catalyst particles to a particle size of 100-200 nm, and the ball milling treatment can further disperse the anode catalyst particle size to below 100 nm. By combining the ultrasonic treatment and the ball milling treatment, the nanosized anode catalyst can be effectively dispersed to a better state, so that the performance of the anode catalyst can be fully exerted.

[0022] In the above-mentioned anode catalyst slurry, the ultrasonic treatment is a high-power dispersion method, which can break up particles and promote uniform mixing. The ultrasonic treatment time can be 0.2 hours to 3 hours, and further can be 0.5 hours to 2 hours. The power of the ultrasonic treatment can be controlled to be less than or equal to 1000W.

[0023] In the anode catalyst slurry, the ball milling process can promote uniform dispersion of the catalyst and resin in the solution. The ball milling process can be performed for 2 to 24 hours, or even 6 to 16 hours. The ball milling process can be performed at a speed of 50 to 800 rpm.

[0024] In the above-mentioned method for preparing the anode catalyst slurry, Figure 1As shown, the present invention first mixes the anode catalyst with the resin. During the mixing process, the resin wraps around the anode catalyst to achieve full bonding between the resin and the anode catalyst. Ultrasonic treatment and ball milling can be used to promote dispersion during this process. Then, a first pore-forming agent is added and the first pore-forming agent is dispersed in the slurry by low-speed stirring (rather than high-power dispersion forms such as high-pressure jetting, high-speed shearing, high-pressure homogenization, and ultrasonic dispersion). This prevents the anode catalyst from being deposited on the surface and internal pores of the first pore-forming agent, thereby preventing the loss of the anode catalyst caused by the removal of the first pore-forming agent and improving the stability of the membrane electrode made of the slurry. In the anode catalyst slurry thus obtained, the anode catalyst is wrapped and bonded by the resin, which prevents the anode catalyst from entering the interior of the first pore-forming agent, thereby preventing the loss of the anode catalyst caused by the subsequent removal of the first pore-forming agent.

[0025] In the anode catalyst slurry, the first pore-forming agent used in the present invention is generally a carbon material that has not been graphitized and has a high specific surface area. This type of carbon material has low chemical stability and a fast reaction rate, and can be removed quickly by methods such as electrochemical corrosion, thereby avoiding catalyst loss caused by prolonged electrochemical treatment. The carbon material includes one or a combination of two or more of activated carbon, graphite powder, carbon nanotubes, and graphene.

[0026] In the above-mentioned anode catalyst slurry, the carbon material includes one or a combination of two or more of activated carbon, graphite powder, and carbon nanotubes.

[0027] In the anode catalyst slurry, the particle size of the carbon material may be 7 nm-2 μm, or 20 nm-200 nm (the particle size of the carbon nanotube is measured in terms of tube diameter).

[0028] In the anode catalyst slurry, the mass content of carbon element in the carbon material may be 99% or more, further 95% or more.

[0029] In the anode catalyst slurry, the mass ratio of the first pore-forming agent to the anode catalyst is generally less than or equal to 1:1, and can be, for example, 0.01:1, 0.05:1, 0.10:1, 0.20:1, 0.30:1, 0.40:1, 0.50:1, 0.60:1, 0.70:1, 0.80:1, 0.90:1, 1.0:1, or a range having any two of the above values as endpoints. The mass ratio of the first pore-forming agent to the anode catalyst can be further controlled to be between 0.01:1 and 0.2:1.

[0030] During the preparation of the anode catalyst slurry, the stirring speed is generally less than or equal to 1000 rpm, further less than or equal to 500 rpm; the stirring time is generally less than or equal to 30 min, further less than or equal to 15 min.

[0031] According to a specific embodiment of the present invention, the anode catalyst layer can be formed by coating an anode catalyst slurry on the surface of a proton exchange membrane. In some specific embodiments, the coating method may include spraying, coating, etc. Specifically, the anode catalyst layer can be formed by coating a cathode catalyst slurry on the surface of a proton exchange membrane and then hot pressing and electrochemical oxidation corrosion, thereby obtaining an anode catalyst layer with a porous structure.

[0032] In the cathode catalyst layer, the cathode catalyst layer is formed of a cathode catalyst slurry, the cathode catalyst slurry includes a cathode catalyst, a resin and a solvent, and the cathode catalyst includes a Pt / C catalyst and / or a Pt black catalyst.

[0033] In the cathode catalyst layer, the mass content of the cathode catalyst in the cathode catalyst layer is 0.1-2.0 mg / cm 2 .

[0034] According to a specific embodiment of the present invention, the mass content of the cathode catalyst in the cathode catalyst slurry is 1%-20%, for example, specific values such as 1%, 2%, 3%, 4%, 5%, 10%, 12%, 15%, 20%, and ranges with any two of the above specific values as endpoints. The mass content of the cathode catalyst in the cathode catalyst slurry can further be 5%-15%.

[0035] In the above-mentioned cathode catalyst layer, the cathode catalyst slurry may also contain a pore-forming agent. Accordingly, the preparation method of the cathode catalyst slurry may specifically include: mixing the cathode catalyst, resin, and solvent to obtain a second intermediate solution; adding the second pore-forming agent to the second intermediate solution and stirring to obtain a cathode catalyst slurry; wherein, the second pore-forming agent includes a carbon material, the stirring speed is less than or equal to 1000 rpm, and the stirring time is less than or equal to 30 min.

[0036] In the cathode catalyst slurry, the mixing process of the cathode catalyst, resin, and solvent includes mixing and uniformly dispersing the cathode catalyst, resin, and solvent to obtain a second intermediate solution. This mixing and uniform dispersion process can improve the dispersion of the nanosized cathode catalyst and facilitate sufficient contact between the cathode catalyst and the resin. More specifically, the mixing process of the cathode catalyst, resin, and solvent can include ultrasonicating and / or ball-milling the mixture to obtain the second intermediate solution. Specifically, the mixture can be subjected to either ultrasonic treatment or ball milling alone, or a combination of both treatments.

[0037] In the above preparation method, the ultrasonic treatment and ball milling treatment can fully disperse the cathode catalyst (nanosized) so that the cathode catalyst is in full contact with the resin. In some specific embodiments, the ultrasonic treatment and ball milling treatment can be performed sequentially, wherein the ultrasonic treatment can disperse the cathode catalyst particles to a particle size of 100-200nm, and the ball milling treatment can further disperse the cathode catalyst particle size to below 100nm. By combining the ultrasonic treatment and the ball milling treatment, the nanosized cathode catalyst can be effectively dispersed to a better state, so that the performance of the cathode catalyst can be fully exerted.

[0038] In the cathode catalyst slurry, the ultrasonic treatment is a high-power dispersion method to break up particles and promote uniform mixing. The ultrasonic treatment time can be 0.2 hours to 3 hours, and further can be 0.5 hours to 2 hours. The ultrasonic treatment power can be controlled to be less than or equal to 1000W.

[0039] In the cathode catalyst slurry, the ball milling process can promote uniform dispersion of the catalyst and resin in the solution. The ball milling process can be performed for 2 to 24 hours, or even 6 to 16 hours. The ball milling process can be performed at a speed of 50 to 800 rpm.

[0040] In the above-mentioned method for preparing the cathode catalyst slurry, Figure 1 As shown, the present invention first mixes the cathode catalyst with the resin. During the mixing process, the resin wraps around the cathode catalyst to achieve full bonding between the resin and the cathode catalyst. Ultrasonic treatment and ball milling can be used to promote dispersion during this process. Then, a pore-forming agent is added and the pore-forming agent is dispersed in the slurry by low-speed stirring (rather than high-power dispersion forms such as high-pressure jets, high-speed shearing, high-pressure homogenization, and ultrasonic dispersion). This prevents the cathode catalyst from being deposited on the surface and in the internal pores of the pore-forming agent, thereby preventing the loss of the cathode catalyst caused by the removal of the pore-forming agent and improving the stability of the membrane electrode made of the slurry. In the cathode catalyst slurry thus obtained, the cathode catalyst is wrapped and bonded by the resin, which prevents the cathode catalyst from entering the interior of the pore-forming agent, thereby preventing the loss of the cathode catalyst caused by the subsequent removal of the pore-forming agent.

[0041] According to a specific embodiment of the present invention, when the cathode catalyst slurry comprises a second pore former, the cathode catalyst is generally a Pt black catalyst.

[0042] In the cathode catalyst slurry, the mass ratio of the second pore-forming agent to the cathode catalyst is generally less than or equal to 1:1, and can be, for example, 0.01:1, 0.05:1, 0.10:1, 0.20:1, 0.30:1, 0.40:1, 0.50:1, 0.60:1, 0.70:1, 0.80:1, 0.90:1, 1.0:1, or a range having any two of the above values as endpoints. The mass ratio of the second pore-forming agent to the cathode catalyst can be further controlled to be between 0.01:1 and 0.2:1.

[0043] In the cathode catalyst slurry, the mass ratio of the resin to the cathode catalyst is 2-10:10, and specifically can be 2:10, 3:10, 4:10, 5:10, 6:10, 7:10, 8:10, 9:10, 10:10, or a range having any two of the above values as endpoints. The mass ratio of the resin to the cathode catalyst can be further controlled to be 2-5:10.

[0044] In the cathode catalyst slurry, the resin includes perfluorosulfonic acid resin.

[0045] In the cathode catalyst slurry, the resin has a kinetic diameter of 100-1000 nm in the cathode catalyst slurry.

[0046] In the cathode catalyst slurry, the solvent includes water and / or alcohol. The alcohol may include one or a combination of two or more of ethanol, isopropanol, n-propanol, and propylene glycol. In some specific embodiments, when the solvent includes water and alcohol, the mass ratio of water to alcohol is 1:9-9:1, and further may be 3:7-8:2.

[0047] In the cathode catalyst slurry, the second pore-forming agent used in the present invention is generally a carbon material that has not been graphitized and has a high specific surface area. This type of carbon material has low chemical stability and a fast reaction rate, and can be removed quickly by methods such as electrochemical corrosion, thus avoiding catalyst loss caused by prolonged electrochemical treatment. The carbon material includes one or a combination of two or more of activated carbon, graphite powder, carbon nanotubes, and graphene.

[0048] In the cathode catalyst slurry, the carbon material includes one or a combination of two or more of activated carbon, graphite powder, and carbon nanotubes.

[0049] In the cathode catalyst slurry, the particle size of the carbon material may be 7 nm to 2 μm, and further may be 20 nm to 200 nm (the particle size of the carbon nanotube is measured in terms of tube diameter).

[0050] In the cathode catalyst slurry, the carbon material has a carbon element content of 99% by mass or more, and further 95% by mass or more.

[0051] According to a specific embodiment of the present invention, the type and particle size of the carbon material used in the first pore-forming agent and the second pore-forming agent may be the same or different.

[0052] In the above-mentioned method for preparing cathode catalyst slurry, the stirring speed is generally controlled to be less than or equal to 1000 rpm, and further controlled to be less than or equal to 500 rpm; the stirring time is generally controlled to be less than or equal to 30 minutes, and further controlled to be less than or equal to 15 minutes.

[0053] According to a specific embodiment of the present invention, the cathode catalyst layer can be formed by applying the cathode catalyst slurry to the surface of the proton exchange membrane and then hot pressing. In some specific embodiments, the coating method may include spraying, coating, etc. Furthermore, when the cathode catalyst slurry contains a second pore-forming agent, the cathode catalyst layer can be formed by applying the cathode catalyst slurry to the surface of the proton exchange membrane and then hot pressing and electrochemical oxidation corrosion, thereby forming a cathode catalyst layer having a porous structure.

[0054] The present invention also provides a method for preparing the membrane electrode, which may include:

[0055] S1. Applying the anode catalyst slurry and the cathode catalyst slurry to opposite sides of the proton exchange membrane respectively, and hot pressing to form the anode catalyst layer and the cathode catalyst layer;

[0056] S2. Covering the anode gas diffusion layer on the surface of the anode catalyst layer, covering the cathode gas diffusion layer on the surface of the cathode catalyst layer, performing electrochemical oxidation corrosion on one side of the anode catalyst layer, removing the anode gas diffusion layer and the cathode gas diffusion layer, and obtaining the membrane electrode.

[0057] In the above preparation method, when the cathode catalyst slurry contains a second pore-forming agent, S2 of the above preparation method further includes an operation of performing electrochemical oxidation corrosion on the cathode catalyst layer.

[0058] In response to the shortcomings of existing membrane electrode preparation methods, the present invention can prepare a membrane electrode containing a carbon material pore-forming agent by adding carbon material to the anode catalyst slurry (carbon material can also be added to the cathode catalyst slurry). The carbon material in the catalytic layer is then selectively removed by an electrochemical corrosion process to form large-sized pores, thereby reducing the mass transfer resistance of the liquid and gas phases, thereby improving the performance and durability of the membrane electrode.

[0059] In the anode catalyst slurry containing the first pore-forming agent, since the anode catalyst is composed of highly active iridium-based nanoparticles, the catalyst surface is partially oxidized during the electrochemical oxidative corrosion process. At this point, the anode catalyst comprises at least iridium oxide and may further comprise unoxidized elemental iridium black. Both iridium oxide and elemental iridium black have excellent catalytic properties (including catalytic activity and stability), so the aforementioned electrochemical oxidative corrosion has no significant effect on the catalytic performance of the anode catalyst.

[0060] In the cathode catalyst slurry containing the second pore-forming agent, the Pt black catalyst serving as the cathode catalyst will undergo trace oxidation on its surface during a higher constant potential process, but this oxidation state can be reduced under subsequent normal operating conditions, that is, the oxidation of the Pt black catalyst during the electrochemical oxidation corrosion process is "reversible", and the above-mentioned process of removing the pore-forming agent through electrochemical oxidation corrosion will not affect the surface chemical state of the Pt black catalyst during the normal operation of the membrane electrode.

[0061] During the electrochemical oxidation corrosion process, by controlling the potential and corrosion time within a reasonable range, the performance of the catalytic layer can meet the requirements of the water electrolysis process. Specifically, the voltage of the electrochemical oxidation corrosion can be controlled to 0.6V-1.5V, and the time of the electrochemical oxidation corrosion can be controlled to 2h-240h.

[0062] The present invention also provides an electrochemical device, comprising the membrane electrode provided by the present invention. The electrochemical device of the present invention has high operating efficiency and high durability.

[0063] In some specific embodiments, the electrochemical device may include an electrolyzer and / or a hydrogen fuel cell, wherein the hydrogen fuel cell includes a membrane electrode. The electrolyzer may specifically include a cathode diffusion layer, a membrane electrode, and an anode diffusion layer stacked in sequence, and the membrane electrode included in the hydrogen fuel cell and the electrolyzer may include the membrane electrode provided by the present invention.

[0064] The present invention also provides a method for producing hydrogen by electrolyzing water, which is performed in the above-mentioned electrochemical device. In some specific embodiments, the method comprises using the above-mentioned membrane electrode provided by the present invention.

[0065] The beneficial effects of the present invention include:

[0066] 1. In the process of preparing the anode catalyst slurry, the present invention fully combines the anode catalyst with the perfluorosulfonic acid resin ionomer and then adds a carbon material pore-forming agent. The carbon material is dispersed in the slurry by low-power stirring, so that the catalyst is deposited as little as possible on the surface and inside of the carbon material, preventing catalyst loss during the process of removing the carbon material pore-forming agent from the catalyst layer, thereby improving the catalytic performance and stability of the catalyst layer and achieving improved membrane electrode stability. Furthermore, the present invention adds an additional porous structure to the cathode catalyst layer to facilitate the rapid discharge of generated hydrogen and reduce the possibility of catalyst layer tearing during long-term operation.

[0067] 2. The catalyst slurry provided by this invention can form a porous catalyst layer with a rich pore structure, reducing the resistance to water and gas transport, and eliminating the possibility of tearing or peeling of the catalyst layer after long-term operation. The performance and durability of the membrane electrode produced by this method are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 Schematic diagram of the process of preparing the anode catalyst slurry and the cathode catalyst slurry containing a pore former according to the present invention. DETAILED DESCRIPTION

[0069] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0070] The raw materials and equipment used in the following examples and comparative examples are from:

[0071] Deionized water: homemade, 18.2 MΩ.

[0072] Anode catalyst: Ir black, IrO produced by Zhongke Kechuang Company x Catalyst. IrO x The x in the catalyst is 2.

[0073] Cathode catalyst: Pt black catalyst and Pt / C catalyst (Pt content 40%) produced by Zhongke Kechuang Company.

[0074] Proton exchange membrane: DuPont 117 proton exchange membrane.

[0075] Carbon material: XC-72 carbon powder (Cabot Corporation, specific surface area 250-260m 2 / g, particle size 20-50nm), high specific surface area activated carbon (Cabot Company, Black Pearl 2000, specific surface area 1450-1550m 2 / g, particle size 15-20nm), nanographite powder (Shanghai Chaowei Nanomaterial Co., Ltd., CW-C-001, average particle size 100nm, average specific surface area 15.6m 2 / g), carbon nanotubes (Jiangsu Tiannai Technology Co., Ltd., FT7000, specific surface area 200-300m 2 / g, average tube diameter 7-11nm, length 5-20μm), graphene (Tanmei New Materials Company, TG1000, specific surface area 600-700m 2 / g, particle size 1-2μm).

[0076] Other reagents: perfluorosulfonic acid resin solution (Chemours), ammonium carbonate, ethanol, isopropanol, propylene glycol (Sinopharm, AR).

[0077] Equipment: Multi-channel PEM water electrolysis membrane electrode test bench.

[0078] Evaluation and analysis method: The membrane electrodes prepared in the examples and comparative examples were tested for the pore properties of the anode catalyst layer using a mercury porosimeter.

[0079] The membrane electrodes prepared in each embodiment and comparative example were installed in the fixture of the membrane electrode test bench for testing. The test conditions were: the membrane electrode working area was 25 cm 2 , water temperature 80℃, current density set at 2A / cm 2 , monitoring the change of voltage over time. The anode diffusion layer in the fixture is titanium felt; the cathode diffusion layer is titanium felt.

[0080] In Examples 1 to 5 and Comparative Examples 1 to 4, the hot pressing temperature was 130° C., the hot pressing pressure was 10 MPa, and the hot pressing time was 3 min.

[0081] Example 1

[0082] This embodiment provides a membrane electrode, the preparation method of which includes:

[0083] 1. If Figure 1 As shown, prepare the anode catalyst slurry:

[0084] (1) An intermediate solution was prepared according to a composition of 1% by mass of an Ir black catalyst, 1.75% by mass of a perfluorosulfonic acid resin solution (with a mass concentration of 20%), and 92% by mass of a solvent. The perfluorosulfonic acid resin was a commercial resin having an equivalent weight of approximately 1000, and the solvent was a mixture of water and isopropyl alcohol in a mass ratio of 1:1.

[0085] Specifically, 1.0 g of Ir black catalyst and 1.75 g of a 20% perfluorosulfonic acid resin solution were added to 92 g of a 1:1 mixture of water and isopropyl alcohol. After mixing, the mixture was ultrasonically crushed for 0.2 hours and then milled in a planetary ball mill at 400 rpm for 24 hours. This yielded an intermediate solution free of pore-forming agent.

[0086] (2) 0.01 g of activated carbon Black Pearl 2000 was added to the intermediate solution of (1) as a carbon material pore-forming agent, and the mixture was stirred at 900 rpm for 10 min using a magnetic stirrer to obtain an anode catalyst slurry containing the carbon material pore-forming agent. The mass concentration of the catalyst in the slurry was 1%, and the mass ratio of the carbon material to the catalyst was 0.01:1.

[0087] 2. Prepare cathode catalyst slurry:

[0088] A cathode catalyst slurry was prepared by ultrasonically dispersing 3% by mass of a Pt / C catalyst, 15% of a 20% perfluorosulfonic acid resin solution, and 90% of a solvent. The perfluorosulfonic acid resin was a commercial resin with an equivalent weight of approximately 1000, and the solvent was a mixture of water and ethanol in a 1:1 mass ratio.

[0089] Specifically, 3.0g of Pt / C catalyst and 15.0g of a 20% perfluorosulfonic acid resin solution were added to 90g of a 1:1 mixture of water and ethanol. The mixture was then ultrasonically dispersed to prepare a cathode catalyst slurry. The catalyst concentration in the slurry was 3%.

[0090] 3. Preparation of membrane electrode:

[0091] The anode catalyst slurry prepared in step 1 and the cathode catalyst slurry prepared in step 2 were sprayed on both sides of the proton exchange membrane by ultrasonic spraying at 95°C on a vacuum heating plate, and hot pressed to form an anode catalyst layer and a cathode catalyst layer; wherein the cathode catalyst loading was 0.5 mg / cm 2 , the anode catalyst loading is 2.0 mg / cm 2 .

[0092] A cathode gas diffusion layer and an anode gas diffusion layer were placed on either side of a proton exchange membrane with a cathode catalyst layer and an anode catalyst layer, respectively, and then mounted on a membrane electrode test bench. Deionized water was introduced into the anode catalyst layer. A power supply was connected, and a positive voltage of 1.5V was applied to the anode side for 120 hours. The carbon material in the anode catalyst layer was removed, and the gas diffusion layer was removed to obtain an activated proton exchange membrane water electrolysis membrane electrode A1. The anode catalyst layer of this membrane electrode has a porous structure.

[0093] Example 2

[0094] This embodiment provides a membrane electrode, the preparation method of which includes:

[0095] 1. If Figure 1 As shown, prepare the anode catalyst slurry:

[0096] (1) An intermediate solution was prepared by combining 5% by mass of an IrOx catalyst, 7% of a 20% by mass perfluorosulfonic acid resin solution, and 88% of a solvent. The 1000-equivalent perfluorosulfonic acid resin was a commercial resin, and the solvent was a mixture of water and ethanol in a 9:1 mass ratio.

[0097] Specifically, 5.0 g of IrOx catalyst and 7.0 g of a 20% perfluorosulfonic acid resin solution were added to 88 g of a 9:1 water / ethanol mixture. After mixing, the mixture was ultrasonically crushed for 1.5 hours and then milled in a planetary ball mill at 400 rpm for 20 hours. This yielded an intermediate solution free of pore-forming agent.

[0098] (2) Add 0.25 g of XC-72 carbon powder (particle size 20-50 nm, a type of activated carbon) as a carbon material pore-forming agent to the catalyst slurry (1) without a pore-forming agent, and stir the mixture at 500 rpm using a magnetic stirrer for 20 min to obtain an anode catalyst slurry containing a carbon material pore-forming agent.

[0099] The mass concentration of the catalyst in the slurry is 5%, and the mass ratio of the carbon material to the catalyst is 0.05:1.

[0100] 2. Prepare cathode catalyst slurry:

[0101] A cathode catalyst slurry was prepared by ultrasonically dispersing 3% by mass of a Pt / C catalyst, 7% of a 20% perfluorosulfonic acid resin solution, and 90% of a solvent. The perfluorosulfonic acid resin was a commercial resin with an equivalent weight of approximately 1000, and the solvent was a mixture of water and ethanol in a 1:1 mass ratio.

[0102] That is, 3.0 g of Pt / C catalyst and 7.0 g of perfluorosulfonic acid resin solution (mass concentration of 20%) were added to 90 g of a mixture of water and ethanol with a mass ratio of 1:1, mixed, and ultrasonically dispersed to prepare a cathode catalyst slurry.

[0103] The mass concentration of the catalyst in the slurry is 3%.

[0104] 3. Preparation of membrane electrode:

[0105] The anode catalyst slurry of this embodiment and the cathode catalyst slurry prepared in step 1 were ultrasonically sprayed on both sides of the proton exchange membrane at 95°C on a vacuum heating plate and hot pressed to form an anode catalyst layer and a cathode catalyst layer; wherein the cathode catalyst loading was 0.5 mg / cm 2 , the anode catalyst loading is 2.0 mg / cm 2 .

[0106] The cathode gas diffusion layer and the anode gas diffusion layer were respectively covered on both sides of the proton exchange membrane with the cathode catalyst layer and the anode catalyst layer, and then installed on a membrane electrode test bench. Deionized water was passed through the anode catalyst layer. The power was turned on and a positive voltage of 1.5V was applied to the anode side for 120 hours. The carbon material in the anode catalyst layer was removed and the gas diffusion layer was removed to obtain an activated proton exchange membrane water electrolysis membrane electrode A2. The anode catalyst layer of this membrane electrode has a porous structure.

[0107] Example 3

[0108] This embodiment provides a membrane electrode, the preparation method of which includes:

[0109] 1. If Figure 1 As shown, prepare the anode catalyst slurry:

[0110] (1) An intermediate solution was prepared by combining 12% by mass of an Ir-based catalyst, 15% of a perfluorosulfonic acid resin solution (with a mass concentration of 20%), and 73% of a solvent. The perfluorosulfonic acid resin was a commercial resin with an equivalent weight of approximately 1000, the solvent was a mixture of water and isopropyl alcohol in a mass ratio of 1:9, and the Ir-based catalyst was a combination of an Ir black catalyst and an IrOx catalyst in a mass ratio of 1:3.

[0111] That is, 3.0 g of Ir black catalyst and 9.0 g of IrO x The catalyst and 15.0 g of a 20% perfluorosulfonic acid resin solution were added to 73 g of a 1:9 mixture of water and isopropyl alcohol. After mixing, the mixture was ultrasonically crushed for 3 hours and then milled in a planetary ball mill at 400 rpm for 16 hours. This yielded an intermediate solution free of pore-forming agent.

[0112] (2) 1.2 g of nanographite powder CW-C-001 was added to the intermediate solution of (1) as a carbon material pore-forming agent, and stirred at 1000 rpm for 25 min using a magnetic stirrer to obtain an anode catalyst slurry containing a carbon material pore-forming agent.

[0113] The mass concentration of the catalyst in the slurry is 12%, and the mass ratio of the carbon material to the catalyst is 0.10:1.

[0114] 2. Prepare cathode catalyst slurry:

[0115] A cathode catalyst slurry was prepared by ultrasonically dispersing 3% by mass of a Pt / C catalyst, 7% of a 20% perfluorosulfonic acid resin solution, and 90% of a solvent. The perfluorosulfonic acid resin was a commercial resin with an equivalent weight of approximately 1000, and the solvent was a mixture of water and ethanol in a 1:1 mass ratio.

[0116] That is, 3.0 g of Pt / C catalyst and 7.0 g of perfluorosulfonic acid resin solution (mass concentration of 20%) were added to 90 g of a mixture of water and ethanol with a mass ratio of 1:1, mixed, and ultrasonically dispersed to prepare a cathode catalyst slurry.

[0117] The mass concentration of the catalyst in the slurry is 3%.

[0118] 3. Preparation of membrane electrode:

[0119] The anode catalyst slurry of this embodiment was coated on both sides of the proton exchange membrane by slit coating method, and the cathode catalyst slurry of step 1 was coated on both sides of the proton exchange membrane by ultrasonic spraying method under the condition of 95°C on a vacuum heating plate, and hot pressed to form the anode catalyst layer and the cathode catalyst layer; the cathode catalyst loading was 0.5 mg / cm 2 , the anode catalyst loading is 2.0 mg / cm 2 .

[0120] The cathode gas diffusion layer and the anode gas diffusion layer were respectively covered on both sides of the proton exchange membrane with the cathode catalyst layer and the anode catalyst layer, and then installed on a membrane electrode test bench. Deionized water was passed through the anode catalyst layer. The power was turned on and a positive voltage of 1.5V was applied to the anode side for 120 hours. The carbon material in the anode catalyst layer was removed and the gas diffusion layer was removed to obtain an activated proton exchange membrane water electrolysis membrane electrode A3. The anode catalyst layer of this membrane electrode has a porous structure.

[0121] Example 4

[0122] This embodiment provides a membrane electrode, the preparation method of which includes:

[0123] 1. If Figure 1 As shown, prepare the anode catalyst slurry:

[0124] (1) An intermediate solution was prepared by combining 20% by mass of an Ir-based catalyst, 20% of a perfluorosulfonic acid resin solution (with a mass concentration of 20%), and 60% of a solvent. The perfluorosulfonic acid resin was a commercial resin with an equivalent weight of approximately 1000, the solvent was a mixture of water and isopropyl alcohol in a mass ratio of 7:3, and the Ir-based catalyst was a combination of an Ir black catalyst and an IrOx catalyst in a mass ratio of 1:3.

[0125] That is, 5.0 g of Ir black catalyst, 15.0 g of IrOx The catalyst and 20.0 g of a 20% perfluorosulfonic acid resin solution were added to 60 g of a 7:3 mixture of water and isopropyl alcohol. After mixing, the mixture was ultrasonically crushed for 3 hours and then milled in a planetary ball mill at 400 rpm for 12 hours. This yielded an intermediate solution free of pore-forming agent.

[0126] (2) 6.0 g of graphene TG1000 as a carbon material pore-forming agent was added to the intermediate solution prepared in (1), and the mixture was stirred at 700 rpm for 30 min using a magnetic stirrer to obtain an anode catalyst slurry containing a carbon material pore-forming agent.

[0127] The mass concentration of the catalyst in the slurry is 20%, and the mass ratio of the carbon material to the catalyst is 0.2:1.

[0128] 2. If Figure 1 As shown, prepare cathode catalyst slurry:

[0129] The cathode catalyst slurry was prepared by ultrasonically dispersing 3% by mass of a Pt black catalyst, 7% of a 20% perfluorosulfonic acid resin solution, and 90% of a solvent. The perfluorosulfonic acid resin was a commercial resin with an equivalent weight of approximately 1000, and the solvent was a mixture of water and ethanol in a 1:1 ratio.

[0130] Specifically, 3.0 g of Pt black catalyst and 7.0 g of a 20% perfluorosulfonic acid resin solution were added to 90 g of a 1:1 mixture of water and ethanol. After mixing, the mixture was first ultrasonically crushed for 3 hours and then milled in a planetary ball mill at 400 rpm for 12 hours. This yielded a second intermediate solution free of pore-forming agent.

[0131] (2) 0.03 g of graphene TG1000 was added to the intermediate solution prepared in (1) as a second pore-forming agent, and the mixture was stirred at 700 rpm for 30 min using a magnetic stirrer to obtain a cathode catalyst slurry containing the second pore-forming agent.

[0132] The mass concentration of the catalyst in the cathode catalyst slurry is 3%, and the mass ratio of the carbon material to the catalyst is 0.01:1.

[0133] 3. Preparation of membrane electrode:

[0134] The anode catalyst slurry of this embodiment was coated on both sides of the proton exchange membrane by slit coating method, and the cathode catalyst slurry of step 1 was coated on both sides of the proton exchange membrane by ultrasonic spraying method under the condition of 95°C on a vacuum heating plate, and hot pressed to form the anode catalyst layer and the cathode catalyst layer; wherein the membrane electrode cathode catalyst loading was 0.5 mg / cm 2 , the anode catalyst loading is 2.0 mg / cm 2 .

[0135] A cathode gas diffusion layer and an anode gas diffusion layer were placed on either side of a proton exchange membrane with a cathode catalyst layer and an anode catalyst layer, respectively, and then installed on a membrane electrode test bench. Deionized water was passed through the anode catalyst layer. A power supply was connected and a positive voltage of 1.5V was applied to the anode side for 120 hours to remove the carbon material in the anode catalyst layer. Deionized water was then passed through the cathode catalyst layer and a positive voltage of 1.3V was applied to the cathode catalyst layer for 120 hours to remove the carbon material in the cathode catalyst layer. The proton exchange membrane was removed and the gas diffusion layer was removed to obtain an activated proton exchange membrane water electrolysis membrane electrode A4. The anode catalyst layer and cathode catalyst layer of the membrane electrode each had a porous structure.

[0136] Example 5

[0137] This embodiment provides a membrane electrode, the preparation method of which includes:

[0138] 1. If Figure 1 As shown, prepare the anode catalyst slurry:

[0139] (1) According to the mass percentage of 4% IrO x An intermediate solution is prepared by combining a catalyst, a 6% perfluorosulfonic acid resin solution (20% by mass concentration), and 90% solvent. The perfluorosulfonic acid resin is a commercial resin with an equivalent weight of approximately 1000, and the solvent is a mixture of water and isopropyl alcohol in a mass ratio of 6:4.

[0140] That is, weigh 4.0g IrO x The catalyst and 6.0 g of a 20% perfluorosulfonic acid resin solution were added to 90 g of a 6:4 mixture of water and isopropyl alcohol. After mixing, the mixture was ultrasonically crushed for 2 hours and then milled in a planetary ball mill at 400 rpm for 6 hours. This yielded an intermediate solution free of pore-forming agent.

[0141] (2) 0.8 g of carbon nanotube FT7000 as a carbon material pore-forming agent was added to the intermediate solution of (1) without a pore-forming agent, and stirred at 600 rpm for 15 min using a magnetic stirrer to obtain an anode catalyst slurry containing a carbon material pore-forming agent.

[0142] The mass concentration of the catalyst in the anode catalyst slurry is 4%, and the mass ratio of the carbon material to the catalyst is 0.2:1.

[0143] 2. If Figure 1 As shown, prepare cathode catalyst slurry:

[0144] (1) An intermediate solution is prepared by combining 4% by mass of a Pt black catalyst, 6% of a perfluorosulfonic acid resin solution (with a mass concentration of 20%), and 90% of a solvent. The perfluorosulfonic acid resin is a commercial resin having an equivalent weight of approximately 1000, and the solvent is a mixture of water and isopropyl alcohol in a mass ratio of 3:7.

[0145] Specifically, 4.0 g of Pt black catalyst and 6.0 g of a 20% perfluorosulfonic acid resin solution were added to 90 g of a 3:7 mixture of water and isopropyl alcohol. After mixing, the mixture was first ultrasonically crushed for 3 hours and then milled in a planetary ball mill at 400 rpm for 2 hours. This yielded an intermediate solution free of pore-forming agent.

[0146] (2) 0.8 g of activated carbon Black Pearl 2000 as a carbon material pore-forming agent was added to the intermediate solution of (1) without a pore-forming agent, and stirred at 600 rpm for 15 min using a magnetic stirrer to obtain a cathode catalyst slurry containing a carbon material pore-forming agent.

[0147] The mass concentration of the catalyst in the cathode catalyst slurry is 4%, and the mass ratio of the carbon material to the catalyst is 0.2:1.

[0148] 3. Preparation of membrane electrode:

[0149] The cathode catalyst slurry prepared in this example and the anode catalyst slurry prepared in this example were sprayed on both sides of the proton exchange membrane by ultrasonic spraying at 95°C on a vacuum heating plate, and hot pressed to form the anode catalyst layer and the cathode catalyst layer; wherein the membrane electrode cathode catalyst loading was 0.5 mg / cm 2 , the anode catalyst loading is 2.0 mg / cm 2 .

[0150] The cathode gas diffusion layer and the anode gas diffusion layer are respectively covered on both sides of the proton exchange membrane with the cathode catalyst layer and the anode catalyst layer, and are installed on a membrane electrode test bench. Deionized water is passed into one side of the anode catalyst layer, and the power is turned on. A positive voltage of 1.5V is applied to the anode side and maintained for 24 hours to remove the carbon material in the anode catalyst layer; then, deionized water is passed into one side of the cathode catalyst layer, and a positive voltage of 1.3V is applied to the cathode side and maintained for 120 hours to remove the carbon material in the cathode catalyst layer; the proton exchange membrane is dismantled, and the gas diffusion layer is removed to obtain an activated proton exchange membrane water electrolysis membrane electrode A5.

[0151] Comparative Example 1

[0152] This comparative example provides a membrane electrode, the preparation method of which includes:

[0153] 1. Preparation of anode catalyst slurry:

[0154] An anode catalyst slurry was prepared by ultrasonically dispersing 3% by mass of an Ir black catalyst, 7% of a perfluorosulfonic acid resin solution (with a mass concentration of 20%), 89% of a solvent, and 1% of ammonium carbonate; wherein the perfluorosulfonic acid resin was a commercial resin with an equivalent weight of approximately 1000, and the solvent was a mixture of water and ethanol solvent in a mass ratio of 1:1.

[0155] That is, 3.0 g of Ir black catalyst, 7.0 g of perfluorosulfonic acid resin solution (mass concentration of 20%), and 1.0 g of ammonium carbonate were weighed and added to 89 g of a mixture of water and ethanol solvent with a mass ratio of 1:1. After mixing, ultrasonic dispersion was performed to prepare an anode catalyst slurry.

[0156] The mass concentration of the catalyst in the slurry is 1%.

[0157] 2. Preparation of cathode catalyst slurry:

[0158] The cathode catalyst slurry was prepared by ultrasonically dispersing a mixture of 3% by mass of a Pt / C catalyst, 7% of a perfluorosulfonic acid resin solution (20% by mass), 89% of a solvent, and 1% of ammonium carbonate. The perfluorosulfonic acid resin is a commercial resin with an equivalent weight of approximately 1000, and the solvent is a mixture of water and ethanol in a 1:1 mass ratio. Specifically, 3.0 g of the Pt / C catalyst, 7.0 g of a perfluorosulfonic acid resin solution (20% by mass), and 1.0 g of ammonium carbonate were weighed and added to 89 g of a 1:1 mass ratio of water and ethanol. After mixing, the mixture was ultrasonically dispersed to prepare the cathode catalyst slurry. The catalyst concentration in the slurry was 3%.

[0159] 3. Membrane electrode preparation:

[0160] The anode catalyst slurry of step 1 and the cathode catalyst slurry of step 2 were sprayed on both sides of the proton exchange membrane by ultrasonic spraying at 95°C on a vacuum heating plate, and hot pressed to form an anode catalyst layer and a cathode catalyst layer; wherein the membrane electrode cathode catalyst loading was 0.5 mg / cm 2 , the anode catalyst loading is 2.0 mg / cm 2 A proton exchange membrane water electrolysis membrane electrode D1 is obtained.

[0161] Comparative Example 2

[0162] This comparative example provides a membrane electrode, the preparation method of which includes:

[0163] 1. Preparation of anode catalyst slurry I:

[0164] The carbon material is carbon nanotubes, the mass ratio of perfluorosulfonic acid ionomer (perfluorosulfonic acid resin) to carbon nanotubes is 0.85:1, and the organic solvent is isopropyl alcohol. The mass percentage of the organic solvent is 50%, and the total mass fraction of the carbon nanotubes and perfluorosulfonic acid ionomer is 1%.

[0165] Specifically, 2.3 g of a 20% perfluorosulfonic acid resin solution and 0.55 g of carbon nanotubes were added to 99 g of a dispersant containing water and isopropyl alcohol in a 1:1 ratio. After mixing, ultrasonic dispersion was performed to prepare an anode catalyst slurry.

[0166] 2. Preparation of anode catalyst slurry II:

[0167] The carbon material uses carbon nanotubes, the mass ratio of perfluorosulfonic acid ionomer to carbon nanotubes is 0.85:1, the organic solvent uses isopropyl alcohol, the mass percentage of the organic solvent is 50%, and the total mass fraction of carbon nanotubes and perfluorosulfonic acid ionomer is 1%.

[0168] Specifically, 2.3 g of a 20% perfluorosulfonic acid resin solution and 0.55 g of carbon nanotubes were added to 99 g of a dispersant containing water and isopropyl alcohol in a 1:1 ratio. After mixing, ultrasonic dispersion was performed to prepare an anode catalyst slurry.

[0169] 3. Preparation of cathode catalyst slurry I:

[0170] The carbon-supported platinum catalyst has a Pt content of 40wt%, the mass ratio of perfluorosulfonic acid ionomer to catalyst carbon support is 0.65:1, the perfluorosulfonic acid ionomer is Nafion, the mass percentage of isopropanol in the dispersant is 50%, and the solid content of the slurry, that is, the total mass fraction of the catalyst and perfluorosulfonic acid ionomer, is 1%.

[0171] Specifically, 2.0 g of a 20% perfluorosulfonic acid resin solution and 0.6 g of a carbon-supported platinum catalyst were added to 99 g of a dispersant containing 1:1 water and isopropyl alcohol. After mixing, the mixture was ultrasonically dispersed to prepare a cathode catalyst slurry.

[0172] 4. Preparation of cathode catalyst slurry II:

[0173] The carbon material uses carbon nanotubes, the mass ratio of perfluorosulfonic acid ionomer to carbon nanotubes is 0.85:1, the organic solvent uses isopropyl alcohol, the mass percentage of the organic solvent is 50%, and the total mass fraction of carbon nanotubes and perfluorosulfonic acid ionomer is 1%.

[0174] Specifically, 2.3 g of a 20% perfluorosulfonic acid resin solution and 0.55 g of carbon nanotubes were added to 99 g of a dispersant containing water and isopropyl alcohol in a 1:1 ratio. After mixing, the mixture was ultrasonically dispersed to prepare a cathode catalyst slurry.

[0175] 5. Preparation of membrane electrode:

[0176] The dispersed cathode catalyst slurry I was loaded into one spray gun, and the dispersed cathode catalyst slurry II was loaded into another spray gun. The cathode catalyst slurry I and cathode catalyst slurry II were alternately sprayed onto the proton exchange membrane to form an interlayer structure to prepare the cathode catalyst layer. The dispersed anode catalyst slurry was loaded into a spray gun and sprayed onto the other side of the proton exchange membrane to prepare the anode catalyst layer. The discharge rate of catalyst slurry I and catalyst slurry II was 0.1 mL min -1 The cathode catalyst loading of the porous membrane electrode is 0.5 mg / cm 2 , the anode catalyst loading is 2.0 mg / cm 2 Finally, the membrane electrode D2 is obtained by hot pressing.

[0177] Comparative Example 3

[0178] This comparative example provides a membrane electrode, the preparation method of which includes:

[0179] 1. Preparation of anode catalyst slurry:

[0180] 1.0 g IrO x The catalyst and 0.3g of XC-72 carbon powder were simultaneously added to 151.5g of a mixture of isopropyl alcohol and propylene glycol in a mass ratio of 48:52, and then 4.6g of Nafion solution (5% by mass concentration) was dropwise added during an ultrasonic process to obtain an anode catalyst slurry containing XC-72 carbon powder. The mass ratio of XC-72 carbon powder to Ir black catalyst was 3:10. Perfluorosulfonic acid resin accounted for 15% of the mass of the anode catalyst layer (the anode catalyst layer was composed of Pt / C catalyst, XC-72 carbon powder, and perfluorosulfonic acid resin in Nafion solution, i.e., the mass ratio of perfluorosulfonic acid resin, XC-72 carbon powder, and Pt / C catalyst was 23:30:100).

[0181] 2. Preparation of cathode catalyst slurry:

[0182] 0.75g of Pt / C catalyst (Pt content 40%) and 6.4g of Nafion solution (mass concentration 5%) were added to 106g of a mixture of isopropyl alcohol and propylene glycol in a 48:52 mass ratio to prepare a cathode catalyst slurry. Perfluorosulfonic acid resin accounted for 30% of the mass of the cathode catalyst layer (the cathode catalyst layer consisted of the Pt / C catalyst and the perfluorosulfonic acid resin in the Nafion solution, i.e., the mass ratio of perfluorosulfonic acid resin to Pt / C catalyst was 3:7). After mixing, ultrasonic dispersion was performed to prepare a cathode catalyst slurry.

[0183] 3. Membrane electrode preparation:

[0184] The anode catalyst slurry prepared in step 1 and the cathode catalyst slurry prepared in step 2 were sprayed onto both sides of the proton exchange membrane respectively and dried to form an anode catalyst layer and a cathode catalyst layer; wherein the membrane electrode cathode catalyst loading was 0.5 mg / cm 2 , the anode catalyst loading is 2.0 mg / cm 2 The cathode gas diffusion layer and the anode gas diffusion layer were respectively covered on both sides of the proton exchange membrane with the cathode and anode catalyst layers, and installed on the membrane electrode test bench. Deionized water was passed into the anode catalyst layer side. The power was turned on and a positive voltage of 1.5V was applied to the anode side for 120 hours to remove the carbon material in the anode catalyst layer and the gas diffusion layer to obtain the membrane electrode D3.

[0185] Comparative Example 4

[0186] This comparative example provides a membrane electrode, and the preparation method of the membrane electrode is as follows:

[0187] 1. Preparation of anode catalyst slurry:

[0188] (1) Preparation of carbon material slurry: Weigh 3.7 g of 20 wt% Chemours D2020 (Nafion TM ) perfluorosulfonic acid resin dispersion, added to a mixed solvent of water and n-propanol, the total weight of water and n-propanol is 94.8 g, wherein the ratio of water to n-propanol is 1:1; stirred evenly, 1.5 g of graphene (TG1000, Tanmei New Materials) (carbon content is about 96%) was added to the above mixed solution, stirred evenly, and dispersed using a high-pressure homogenizer at a dispersion pressure of 35000 psi to obtain a carbon material slurry.

[0189] (2) Preparation of pre-dispersed slurry of anode catalyst. Weigh the IrO x 9.0g of catalyst, weighed 22.5g of 20wt% Chemours D2020 (Nafion TM ) perfluorosulfonic acid resin dispersion, 8.9 g of ethanol, and 59.6 g of ultrapure water; place the agitator in a beaker filled with weighed water and start stirring at a speed of 200 rpm. Slowly add Ir black catalyst to the water and stir for 2 minutes. After ensuring that the catalyst is wetted, add the resin dispersion and stir for 2 minutes. Add ethanol and continue stirring for 5-10 minutes to ensure that the materials are evenly mixed to obtain a pre-dispersed slurry of the anode catalyst.

[0190] (3) Weigh 10 g of the dispersed carbon material slurry and slowly add it to the anode catalyst pre-dispersed slurry in step (2), and continue stirring for 5-10 minutes; disperse it through a Beads mill disperser with a speed of 1000 rpm and a dispersion time of 10 minutes. Then collect the dispersed anode catalyst slurry for degassing to obtain the anode catalyst slurry.

[0191] 2. Preparation of cathode catalyst slurry:

[0192] Weigh 9.0 g of Pt / C catalyst (Pt content 40%), weigh 22.5 g of 20 wt% Chemours D2020 (Nafion TM ) Perfluorosulfonic acid resin dispersion, 8.9 g of ethanol, and 59.6 g of ultrapure water; place the agitator in a beaker filled with the weighed water and start stirring at a speed of 200 rpm. Slowly add the catalyst Pt / C to the water and stir for 2 minutes. After ensuring that the catalyst is wetted, add the resin dispersion and stir for 2 minutes. Add ethanol and continue stirring for 5-10 minutes to ensure that the materials are evenly mixed to obtain a cathode catalyst slurry.

[0193] 3. Membrane electrode preparation:

[0194] The anode catalyst slurry and cathode catalyst slurry were coated on both sides of the proton exchange membrane by slit coating, and hot pressed to obtain the anode catalyst layer and cathode catalyst layer. The membrane electrode cathode catalyst loading was 0.5 mg / cm 2 , the anode catalyst loading is 2.0 mg / cm 2 . A membrane electrode D4 is obtained.

[0195] Test Case

[0196] This test example provides the catalytic performance test results of the membrane electrodes prepared in the above examples and comparative examples.

[0197] The test method is: install the membrane electrode to be tested into the fixture of the membrane electrode test bench for testing. The test conditions are: the cathode diffusion layer and the anode diffusion layer are both titanium felt, and the membrane electrode working area is 25cm 2 , water temperature 80℃, current density set at 2A / cm 2 The initial and final operating voltages of the membrane electrode were tested after 1000 hours of continuous operation. The specific test results are shown in Table 1 below.

[0198] Table 1 Membrane electrode stability test results

[0199] serial number Initial operating voltage End working voltage Example 1 2.03V 2.07V Example 2 2.02V 2.05V Example 3 2.01V 2.04V Example 4 2.00V 2.03V Example 5 1.98V 2.02V Comparative Example 1 2.06V 2.17V Comparative Example 2 2.10V 2.23V Comparative Example 3 2.09V 2.35V Comparative Example 4 2.10V 2.29V

[0200] Table 1 reflects the operating voltage stability of each membrane electrode sample over 1000 hours. As can be seen from Table 1, the initial operating voltage of the membrane electrodes prepared in Comparative Examples 1 to 4 is higher than the initial voltage of the membrane electrodes prepared in Examples 1 to 5; and the final operating voltage of the membrane electrodes in each comparative example has a more significant increase compared to the final voltage of the membrane electrodes prepared in each example. In addition, the difference between the two operating voltages of the membrane electrodes in each comparative example is large, while the difference between the initial operating voltage and the final operating voltage of the membrane electrodes prepared in Examples 1 to 5 is very small. The above results show that the catalytic performance stability of the membrane electrodes prepared in the comparative examples is poor, while the catalytic performance of the membrane electrodes prepared in the examples of the present invention is stable.

[0201] Furthermore, by comparing the test results of the membrane electrode of comparative example 3 with the test results of the membrane electrode prepared in Example 2, it can be seen that the initial working voltage and the final working voltage of the membrane electrode of comparative example 3 are higher than the test voltage of the membrane electrode of Example 2.

[0202] Comparative Example 3 and Example 2 used the same pore-forming agent, but in Comparative Example 3, the pore-forming agent and catalyst were added to the solvent simultaneously, mixed, and ultrasonicated. This caused some catalyst particles to enter the internal pore structure of the carbon powder and the catalyst was not bound to the resin. Therefore, during the process of removing the pore-forming agent, the catalyst inside the pore-forming agent fell off from the catalyst layer, resulting in low membrane electrode stability. In addition, the specific surface area of the pore-forming agent is small, and it takes a long time for the electrochemical oxidation corrosion process to be fully removed, resulting in the continuous loss of catalyst in the anode catalyst layer, further resulting in low membrane electrode stability. The membrane electrode of Comparative Example 3 was subjected to a voltage test, and the operating voltage of the membrane electrode remained unstable within 24 hours.

[0203] In contrast, Example 2 first mixes the resin and catalyst, allowing the resin to fully entangle the catalyst particles and ensure a complete bond between them. A pore-forming agent is then added and dispersed under low-speed stirring to produce a catalyst slurry. This process prevents catalyst particles from entering the pore structure of the pore-forming agent, thus avoiding the problem of catalyst loss during pore-forming agent removal. Therefore, compared to the membrane electrode of Comparative Example 3, the membrane electrode produced in Example 2 using the catalyst slurry obtained through this preparation process exhibits higher catalytic stability and more stable operating voltage.

[0204] The above test results indicate that the present invention can increase the effective catalyst loading in the membrane electrode formed by the catalyst slurry and improve the catalytic performance stability of the membrane electrode by controlling the preparation conditions of the catalyst slurry.

Claims

1. A membrane electrode, comprising a cathode catalyst layer, a proton exchange membrane, and an anode catalyst layer stacked in sequence; in, The anode catalyst layer is formed by anode catalyst slurry; The preparation method of the anode catalyst slurry includes: mixing an anode catalyst, a resin, and a solvent to obtain a first intermediate solution; adding a first pore-forming agent to the first intermediate solution and stirring to obtain an anode catalyst slurry; wherein the first pore-forming agent includes a carbon material, the stirring speed is less than or equal to 1000 rpm, and the stirring time is less than or equal to 30 minutes.

2. The membrane electrode according to claim 1, wherein: The anode catalyst includes Ir black and / or IrOx; Preferably, the anode catalyst comprises Ir black and IrOx in a mass ratio of 1:3-3:

1.

3. The membrane electrode according to claim 1, wherein: The mass content of the anode catalyst in the anode catalyst slurry is 1%-20%, preferably 5%-15%.

4. The membrane electrode according to claim 1, wherein: The mass content of the anode catalyst in the anode catalyst layer is 0.5-5.0 mg / cm 2 .

5. The membrane electrode according to claim 1, wherein: In the anode catalyst slurry, the mass ratio of the resin to the anode catalyst is 2:10-10:10; Preferably, the mass ratio of the resin to the anode catalyst is 2-5:

10.

6. The membrane electrode according to claim 1, wherein: In the anode catalyst slurry, the mass ratio of the first pore-forming agent to the anode catalyst is less than or equal to 1:1; Preferably, the mass ratio of the first pore-forming agent to the anode catalyst is 0.01:1-0.2:

1.

7. The membrane electrode according to claim 1, wherein: The mixing process of the anode catalyst, resin and solvent includes: mixing the catalyst, resin and solvent and uniformly dispersing them to obtain a first intermediate solution; Preferably, the mixing process of the anode catalyst, the resin, and the solvent comprises: subjecting the mixture of the anode catalyst, the resin, and the solvent to ultrasonic treatment and / or ball milling treatment to obtain a first intermediate solution; More preferably, the ultrasonic treatment time is 0.2h-3h, and the ball milling time is 2h-24h; Further preferably, the ultrasonic treatment time is 0.5h-2h, and the ball milling time is 6h-16h.

8. The membrane electrode according to claim 1, wherein: The stirring speed is less than or equal to 500 rpm, and the stirring time is less than or equal to 15 min.

9. The membrane electrode according to claim 1, wherein: The cathode catalyst layer is formed of a cathode catalyst slurry. The cathode catalyst slurry includes a cathode catalyst, a resin, and a solvent. The cathode catalyst includes a Pt / C catalyst and / or a Pt black catalyst.

10. The membrane electrode according to claim 9, wherein: The mass content of the cathode catalyst in the cathode catalyst layer is 0.1-2.0 mg / cm 2 .

11. The membrane electrode according to claim 9, wherein: The preparation method of the cathode catalyst slurry includes: mixing a cathode catalyst, a resin, and a solvent to obtain a second intermediate solution; adding a second pore-forming agent to the second intermediate solution and stirring to obtain a cathode catalyst slurry; wherein the second pore-forming agent includes a carbon material, the stirring speed is less than or equal to 1000 rpm, and the stirring time is less than or equal to 30 minutes.

12. The membrane electrode according to claim 11, wherein: In the cathode catalyst slurry, the mass ratio of the second pore-forming agent to the cathode catalyst is less than or equal to 1:1, preferably 0.01:1-0.2:

1.

13. The membrane electrode according to claim 11, wherein: The cathode catalyst includes Pt black.

14. The membrane electrode according to claim 1 or 11, wherein: The carbon material includes one or a combination of two or more of activated carbon, graphite powder, carbon nanotubes, and graphene; Preferably, the carbon material comprises one or a combination of two or more of activated carbon, graphite powder, and carbon nanotubes; Preferably, the particle size of the carbon material is 7 nm-2 μm, or 20 nm-200 nm.

15. The method for preparing the membrane electrode according to any one of claims 1 to 14, comprising: S1. Applying the anode catalyst slurry and the cathode catalyst slurry to opposite sides of the proton exchange membrane respectively, and hot pressing to form the anode catalyst layer and the cathode catalyst layer; S2, covering the surface of the anode catalyst layer with an anode gas diffusion layer, covering the surface of the cathode catalyst layer with a cathode gas diffusion layer, performing electrochemical oxidation corrosion on one side of the anode catalyst layer, removing the anode gas diffusion layer and the cathode gas diffusion layer, and obtaining the membrane electrode; Preferably, the voltage of the electrochemical oxidation corrosion is 0.6V-1.5V, and the time of the electrochemical oxidation corrosion is 2h-240h.

16. An electrochemical device comprising the membrane electrode according to any one of claims 1 to 14; Preferably, the electrochemical device includes an electrolyzer and / or a hydrogen fuel cell, the electrolyzer includes a cathode diffusion layer, a membrane electrode and an anode diffusion layer stacked in sequence; the hydrogen fuel cell includes a membrane electrode, and the membrane electrode includes the membrane electrode according to any one of claims 1-14.

17. A method for producing hydrogen by electrolyzing water, the method being carried out in the electrochemical device according to claim 16.

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