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 an anode catalyst layer, a proton exchange membrane and a cathode catalyst layer which are sequentially stacked, the anode catalytic layer comprises more than two stacked anode catalytic sub-layers, and the porosity of each anode catalytic sub-layer is increased from the proton exchange membrane to the outside; the anode catalytic sub-layer is formed by anode catalyst slurry; a preparation method of the anode catalyst slurry comprises the following steps: mixing an anode catalyst, resin and a solvent to obtain the anode catalyst slurry; or mixing the anode catalyst, the resin and the solvent to obtain a first intermediate solution, adding the first pore-forming agent into the first intermediate solution, and stirring to obtain the anode catalyst slurry. The invention also provides a preparation method of the membrane electrode and application of the membrane electrode. The membrane electrode can reduce the transmission resistance of gas and is stable in catalytic performance.

Description

Technical Field

[0001] The present invention relates to the technical field of water electrolysis, and in particular to a membrane electrode and a preparation method thereof, an electrochemical device and a method for producing hydrogen by electrolyzing 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, but 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 catalyst 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] In order to solve the above problems, the present invention aims to provide a membrane electrode, a preparation method thereof, an electrochemical device and a method for producing hydrogen by electrolysis of water. The membrane electrode can reduce gas transmission resistance and has stable catalytic performance.

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

[0010] The anode catalyst layer comprises two or more stacked anode catalyst sublayers; the porosity of each anode catalyst sublayer increases from the proton exchange membrane outward;

[0011] Each anode catalytic sub-layer is formed by an anode catalyst slurry. The preparation method of the anode catalyst slurry includes method a or method b:

[0012] Method a: mixing an anode catalyst, a resin, and a solvent to obtain an anode catalyst slurry;

[0013] Method b: 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 comprises 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;

[0014] When the anode catalytic sublayer is the sublayer with the shortest distance from the proton exchange membrane, the preparation method of the anode catalyst slurry corresponding to the anode catalytic sublayer is method a or method b;

[0015] When the anode catalytic sublayer is not the sublayer with the shortest distance from the proton exchange membrane, the preparation method of the anode catalyst slurry corresponding to the anode catalytic sublayer is method b.

[0016] In the aforementioned anode catalyst layer, each anode catalyst sublayer is formed from an anode catalyst slurry. The anode catalyst slurry corresponding to the anode catalyst sublayer closest to the proton exchange membrane may or may not contain a first pore-forming agent. The slurries of all anode catalyst sublayers, except for the sublayer closest to the proton exchange membrane, contain a first pore-forming agent. The porosity of each anode catalyst sublayer can be adjusted by adjusting the amount and / or particle size of the first pore-forming agent in each anode catalyst slurry.

[0017] In the above-mentioned anode catalyst layer, in method a and method b, the mass content of the anode catalyst in each anode catalyst sublayer is 0.5-5.0 mg / cm 2 .

[0018] In the above-mentioned anode catalyst layer, in method a and method b, the anode catalyst includes Ir black and / or IrOx (iridium oxide, 1≤x≤2), and the anode catalyst slurry formed thereby is a PEMWE anode catalyst slurry.

[0019] In the 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. In some specific embodiments, the mass ratio of Ir black to IrOx may be specific values such as 1:3, 1:2, 1:1, 2:1, 3:1, and ranges with any two of the above specific values as endpoints.

[0020] In the above-mentioned anode catalyst slurry, in method a and method b, the mass content of the anode catalyst in the anode 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 anode catalyst in the anode catalyst slurry can further be 5%-15%.

[0021] In the above anode catalyst slurry, in method a and method b, the resin includes perfluorosulfonic acid resin.

[0022] In the above anode catalyst slurry, in method a and method b, the kinetic diameter of the resin in the anode catalyst slurry is 100-1000 nm.

[0023] In the above-mentioned anode catalyst slurry, in method a and method b, the mass ratio of the resin to the anode catalyst is 2:10-10:10, and can specifically 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 anode catalyst can further be 2:10-5:10.

[0024] In the above-mentioned anode catalyst slurry, in methods a and b, the solvent comprises water and / or alcohol. The alcohol may comprise one or a combination of two or more of ethanol, isopropanol, n-propanol, and propylene glycol. In some specific embodiments, when the solvent comprises water and alcohol, the mass ratio of the water to alcohol is 1:9-9:1, and further may be 3:7-8:2.

[0025] In the above-mentioned anode catalyst slurry, in method b, 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 specifically 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, and other specific values, as well as ranges with any two of the above specific values as endpoints. The mass ratio of the first pore-forming agent to the anode catalyst can further be controlled to be 0.01:1-0.2:1.

[0026] 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.

[0027] 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.

[0028] In the anode catalyst slurry, the particle size of the carbon material may be 7 nm to 2 μm, or further may be 20 nm to 200 nm. When the carbon material is carbon nanotubes, the particle size of the carbon nanotubes is measured in terms of tube diameter.

[0029] In the anode catalyst slurry, the mass content of carbon element in the carbon material may be 99% or more, further 95% or more.

[0030] In the above-mentioned anode catalyst slurry, in method a and method b, the mixing process of the anode catalyst, resin, and solvent includes: mixing and uniformly dispersing the anode catalyst, resin, and solvent to obtain an anode catalyst slurry (method a) or a first intermediate solution (method b). The mixing and uniform dispersion process can improve the dispersion degree of the nano-sized anode catalyst, which is conducive to sufficient contact between the anode catalyst and the resin. More specifically, the mixing process of the anode catalyst, resin, and solvent can include: ultrasonically treating and / or ball-milling the mixture of the anode catalyst, resin, and solvent to obtain an anode catalyst slurry (method a) or a first intermediate solution (method b). That is, the mixture can be subjected to a separate ultrasonic treatment or ball-milling treatment, or a combination of the two treatments.

[0031] 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 particles to a particle size of less than 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.

[0032] 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.

[0033] In the anode catalyst slurry, the ball milling process can promote uniform dispersion of the anode catalyst and the 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.

[0034] In the above-mentioned method for preparing the anode catalyst slurry, Figure 1 As 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. During this process, ultrasonic treatment and ball milling can be used to promote uniform dispersion. Then, in method b, the 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.

[0035] In the preparation process of the anode catalyst slurry, in method b, 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.

[0036] 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 the anode catalyst slurry on the surface of a proton exchange membrane and then hot pressing and electrochemical oxidation corrosion, so that the resulting anode catalyst layer has a porous structure.

[0037] According to a specific embodiment of the present invention, the anode catalyst layer may be formed by stacking two or more anode catalyst sub-layers. Further, the anode catalyst layer may include 2-5 anode catalyst sub-layers.

[0038] According to a specific embodiment of the present invention, any two anode catalytic sublayers are respectively recorded as sublayer A and sublayer B, the distance between sublayer B and the proton exchange membrane is greater than the distance between sublayer A and the proton exchange membrane, and the porosity of sublayer B is greater than the porosity of sublayer A. Among the two adjacent anode catalytic sublayers, the porosity of the anode catalytic sublayer farther from the proton exchange membrane is greater than that of the other anode catalytic sublayer. From the proton exchange membrane to the outside, the porosity of the anode catalytic sublayer gradually increases. The present invention controls the porosity of the anode catalyst layer to gradually increase from the proton exchange membrane to the outside, which can reduce the transmission resistance of the gas from the inner layer (close to the proton exchange membrane) to the outer layer (far away from the proton exchange membrane) during the electrolysis of water reaction, increase the transmission speed of water and oxygen, avoid the formation of gas accumulation in the middle sublayer and the resulting slowdown of water molecule movement and expansion, crushing and peeling of the catalyst layer structure, thereby improving the reaction efficiency and improving the stability of the catalytic performance of the catalyst layer.

[0039] According to specific embodiments of the present invention, each anode catalytic sub-layer is formed from an anode catalyst slurry. For an anode catalyst slurry containing a first pore-forming agent, the anode catalytic sub-layer formed therefrom may have a porous structure formed by the first pore-forming agent. The porosity of each anode catalytic layer can be adjusted by adjusting the amount of the first pore-forming agent relative to the anode catalyst in the anode catalyst slurry and / or the particle size range of the first pore-forming agent. In some specific embodiments, a higher mass ratio of the first pore-forming agent to the anode catalyst and a larger particle size of the first pore-forming agent increase the porosity of the anode catalytic sub-layer formed from the anode catalyst slurry.

[0040] According to a specific embodiment of the present invention, as described above, any two anode catalyst sublayers are respectively recorded as sublayer A and sublayer B, said sublayer A is formed by anode catalyst slurry A, and sublayer B is formed by anode catalyst slurry B. When the porosity of sublayer B is greater than the porosity of sublayer A (at this time, the distance between sublayer B and the proton exchange membrane is greater than the distance between sublayer A and the proton exchange membrane), and the anode catalyst slurry A and the anode catalyst slurry B respectively contain a first pore-forming agent (that is, slurry A and slurry B are prepared by method b): the particle size of the first pore-forming agent in the anode catalyst slurry B is greater than the particle size of the first pore-forming agent in the anode catalyst A slurry; and / or, the mass ratio of the first pore-forming agent in the anode catalyst slurry B to the anode catalyst in the slurry is greater than the mass ratio of the first pore-forming agent in the anode catalyst slurry A to the anode catalyst in the slurry.

[0041] According to a specific embodiment of the present invention, the cathode catalyst layer may include 1-5 stacked cathode catalyst sub-layers.

[0042] In the cathode catalyst layer, each cathode catalyst sub-layer is formed by a cathode catalyst slurry, and the cathode catalyst slurry includes a cathode catalyst, a resin and a solvent;

[0043] When the cathode catalyst has one cathode catalytic sublayer, the cathode catalyst includes a Pt / C catalyst and / or a Pt black catalyst;

[0044] When the cathode catalyst has two or more cathode catalytic sub-layers, the cathode catalyst includes a Pt black catalyst.

[0045] 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 .

[0046] 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%.

[0047] 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.

[0048] In the cathode catalyst slurry, the resin includes perfluorosulfonic acid resin.

[0049] In the cathode catalyst slurry, the resin has a kinetic diameter of 100-1000 nm in the cathode catalyst slurry.

[0050] 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, isopropyl alcohol, isopropyl alcohol, 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.

[0051] In the cathode catalyst layer, the cathode catalyst slurry may optionally contain or not contain a pore-forming agent. Accordingly, the preparation method of the cathode catalyst slurry may specifically include method c and method d:

[0052] Method c comprises: mixing a cathode catalyst, a resin, and a solvent to obtain a cathode catalyst slurry;

[0053] Method d comprises: 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 comprises 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;

[0054] When the cathode catalytic sublayer is the sublayer with the shortest distance from the proton exchange membrane, the preparation method of the cathode catalyst slurry corresponding to the cathode catalytic sublayer is method c or method d;

[0055] When the cathode catalytic sublayer is not the sublayer with the shortest distance from the proton exchange membrane, the preparation method of the cathode catalyst slurry corresponding to the cathode catalytic sublayer is method d.

[0056] In the above-mentioned cathode catalyst slurry, in method a and method b, the mixing process of the cathode catalyst, resin, and solvent can specifically include: mixing and uniformly dispersing the cathode catalyst, resin, and solvent to obtain a cathode catalyst slurry (method c) or a second intermediate solution (method d). The mixing and uniform dispersion process can improve the dispersion degree of the nano-sized cathode catalyst, which is conducive to sufficient contact between the cathode catalyst and the resin. More specifically, the mixing process of the cathode catalyst, resin, and solvent can include: ultrasonically treating and / or ball-milling the mixture of the cathode catalyst, resin, and solvent to obtain a cathode catalyst slurry (method c) or a second intermediate solution (method d). That is, the mixture can be subjected to a single ultrasonic treatment or ball-milling treatment, or a combination of the two treatments.

[0057] 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 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 cathode catalyst particles to a particle size of 100-200nm, and the ball milling treatment can further disperse the cathode catalyst particles to a particle size of less than 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.

[0058] 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.

[0059] In the cathode catalyst slurry, the ball milling process can promote uniform dispersion of the cathode catalyst and the 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.

[0060] 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. During this process, ultrasonic treatment and ball milling can be used to promote uniform dispersion. Then, in method d, the second pore-forming agent is added and the second pore-forming agent is dispersed in the slurry by low-speed stirring (rather than high-power dispersion forms such as high-pressure jet, high-speed shear, high-pressure homogenization, and ultrasonic dispersion). This prevents the cathode catalyst from being deposited on the surface and internal pores of the second pore-forming agent, thereby preventing the loss of the cathode catalyst caused by the removal of the second 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 second pore-forming agent, thereby preventing the loss of the cathode catalyst caused by the subsequent removal of the second pore-forming agent.

[0061] According to a specific embodiment of the present invention, in method d, the cathode catalyst slurry contains a second pore-forming agent, and the cathode catalyst is generally a Pt black catalyst.

[0062] According to a specific embodiment of the present invention, the type of cathode catalyst may include the following:

[0063] (1) The cathode catalyst layer includes one cathode catalyst sublayer, and the cathode catalyst slurry corresponding to the cathode catalyst sublayer is prepared by method c (the slurry does not contain a second pore-forming agent), and the cathode catalyst in the cathode catalyst slurry includes a Pt / C catalyst and / or a Pt black catalyst;

[0064] (2) The cathode catalyst layer includes one cathode catalyst sublayer, and the cathode catalyst slurry corresponding to the cathode catalyst sublayer is prepared by method d (the slurry contains a second pore-forming agent), and the cathode catalyst in the cathode catalyst slurry includes a Pt black catalyst;

[0065] (3) The cathode catalyst layer contains more than two cathode catalyst sublayers, and the cathode catalyst slurry corresponding to the cathode catalyst sublayer closest to the proton exchange membrane is prepared using method c (the slurry does not contain the second pore-forming agent), and the cathode catalyst slurries corresponding to the remaining cathode catalyst sublayers are prepared using method d (the slurry contains the second pore-forming agent), then the cathode catalyst in all cathode catalyst slurries includes Pt black catalyst;

[0066] (4) The cathode catalyst layer contains more than two cathode catalyst sublayers, and the cathode catalyst slurry corresponding to the cathode catalyst sublayer closest to the proton exchange membrane is made using method d (the slurry contains a second pore-forming agent), and the cathode catalyst slurries corresponding to the remaining cathode catalyst sublayers are made using method d (the slurry contains a second pore-forming agent), then the cathode catalyst in all the cathode catalyst slurries includes Pt black catalyst.

[0067] In the cathode catalyst slurry described above, in method b, the mass ratio of the second pore-forming agent to the cathode catalyst is generally less than or equal to 1:1, and can specifically be 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, and other specific values, as well as ranges with any two of the above specific values as endpoints. The mass ratio of the second pore-forming agent to the cathode catalyst can be further controlled to be 0.01:1-0.2:1.

[0068] 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.

[0069] 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.

[0070] In the cathode catalyst slurry, the particle size of the carbon material may be 7 nm to 2 μm, or further may be 20 nm to 200 nm. When the carbon material is a carbon nanotube, the particle size of the carbon nanotube is measured in terms of tube diameter.

[0071] 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.

[0072] 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.

[0073] In the above-mentioned method for preparing cathode catalyst slurry, in method b, 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.

[0074] 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.

[0075] According to a specific embodiment of the present invention, when the cathode catalyst layer includes two or more stacked cathode catalyst sublayers, any two cathode catalyst sublayers are respectively recorded as sublayer C and sublayer D, the distance between sublayer D and the proton exchange membrane is greater than the distance between sublayer C and the proton exchange membrane, and the porosity of sublayer D is greater than the porosity of sublayer C. Among the two adjacent cathode catalyst sublayers, the porosity of the cathode catalyst sublayer farther from the proton exchange membrane is greater than that of the other cathode catalyst sublayer. That is, the porosity of the cathode catalyst sublayer gradually increases from the proton exchange membrane to the outside. The present invention controls the porosity of the cathode catalyst layer to gradually increase from the proton exchange membrane to the outside, thereby reducing the gas transmission resistance from the inner layer (close to the proton exchange membrane) to the outer layer (far away from the proton exchange membrane) during the water electrolysis reaction, increasing the transmission speed of water and oxygen, avoiding the formation of gas accumulation in the middle sublayer and the resulting slowdown of water molecule movement and expansion, crushing and peeling of the catalyst layer structure, thereby improving the reaction efficiency and improving the stability of the catalytic performance of the catalyst layer.

[0076] According to a specific embodiment of the present invention, each cathode catalytic sublayer is formed by a cathode catalyst slurry. The cathode catalyst slurry contains a second pore-forming agent, and the cathode catalytic sublayer formed therefrom has a porous structure formed by the second pore-forming agent. The porosity of each cathode catalytic layer can be adjusted by adjusting the amount of the second pore-forming agent relative to the cathode catalyst in the cathode catalyst slurry and / or the particle size range of the second pore-forming agent. In some specific embodiments, the higher the mass ratio of the second pore-forming agent to the cathode catalyst and the larger the particle size of the second pore-forming agent, the greater the porosity of the cathode catalytic sublayer formed by the cathode catalyst slurry.

[0077] According to a specific embodiment of the present invention, the sublayer C is formed by cathode catalyst slurry C, and the sublayer D is formed by cathode catalyst slurry D. When the porosity of sublayer D is greater than the porosity of sublayer C, and cathode catalyst slurry C and cathode catalyst slurry D respectively contain a second pore-forming agent (that is, slurry C and slurry D are prepared by method d): the particle size of the second pore-forming agent in the cathode catalyst slurry D is greater than the particle size of the second pore-forming agent in the cathode catalyst slurry C; and / or, the mass ratio of the second pore-forming agent in the cathode catalyst slurry D to the cathode catalyst in the slurry is greater than the mass ratio of the second pore-forming agent in the cathode catalyst slurry C to the cathode catalyst in the slurry.

[0078] The present invention also provides a method for preparing the membrane electrode, which may include:

[0079] 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;

[0080] 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.

[0081] According to a specific embodiment of the present invention, S1 of the above-mentioned method for preparing the anode catalyst layer may specifically include: sequentially coating two or more anode catalyst slurries on the surface of the proton exchange membrane, and forming a stacked anode catalyst sublayer by hot pressing.

[0082] In the above preparation method, when the cathode catalyst layer includes more than two cathode catalyst sub-layers, S1 of the above preparation method of the cathode catalyst layer may include: sequentially coating more than two cathode catalyst slurries on the surface of the proton exchange membrane, and forming a stacked cathode catalyst sub-layer through hot pressing and electrochemical corrosion.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] The effects of the present invention include:

[0092] 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.

[0093] 2. The catalyst slurry provided by the present invention can form a catalytic layer with a porous structure. The pore structure in the catalytic layer is rich, and the resistance to water molecule and gas transmission is reduced, which solves the possibility of the catalytic layer tearing or peeling after long-term operation. The performance and durability of the membrane electrode produced in this way are significantly improved. Furthermore, the arrangement of the catalytic sublayers on the same side with increasing porosity in the present invention can reduce the transmission resistance of gas from the inner layer to the outer layer during the water electrolysis reaction, increase the transmission speed of water and oxygen, and improve the stability of the catalytic performance of the catalytic layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Figure 1 Schematic diagram of the process of preparing the anode catalyst slurry and the cathode slurry containing a pore-forming agent in the present invention.

[0095] Figure 2 Schematic diagram of the structure of the membrane electrode of Examples 1 to 3.

[0096] Figure 3 Schematic diagram of the structure of the membrane electrode of Examples 4 and 5.

[0097] Explanation of symbols

[0098] Anode catalyst layer 1, proton exchange membrane 2, cathode catalyst layer 3, anode catalyst sublayer 11, cathode catalyst sublayer 31, pore 4. DETAILED DESCRIPTION

[0099] 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.

[0100] The raw materials and equipment used in the following experiments are from:

[0101] Deionized water: homemade, 18.2 MΩ

[0102] Anode catalyst: Ir black, IrO produced by Zhongke Kechuang Company x catalyst.

[0103] Cathode catalyst: Pt black catalyst and Pt / C catalyst (Pt content 40%) produced by Zhongke Kechuang Company.

[0104] Proton exchange membrane: DuPont 117 proton exchange membrane.

[0105] 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).

[0106] Other reagents: perfluorosulfonic acid resin solution (Chemours), ammonium carbonate, ethanol, isopropanol, propylene glycol (Sinopharm, AR).

[0107] Equipment: Multi-channel PEM water electrolysis membrane electrode test bench.

[0108] Evaluation and analysis method: First, 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. Then, the membrane electrodes 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.

[0109] The hot pressing temperature used in the following examples and comparative examples was 130° C., the hot pressing pressure was 10 MPa, and the hot pressing time was 3 min.

[0110] Preparation Examples: The following preparation examples provide methods for preparing the anode catalyst slurry and cathode catalyst slurry used in each example.

[0111] Anode catalyst slurry 1:

[0112] like Figure 1 As shown, the preparation method of the slurry includes:

[0113] (1) An intermediate solution is prepared according to 1% by mass of Ir black catalyst, 1.75% of perfluorosulfonic acid resin solution (mass concentration is 20%) and 92% of solvent. The perfluorosulfonic acid resin is a commercial resin with an equivalent weight of about 1000, and the solvent is a mixture of water and isopropyl alcohol in a mass ratio of 1:1. That is, 1.0g of Ir black catalyst and 1.75g of perfluorosulfonic acid resin solution (mass concentration is 20%) are weighed and added to 92g of a mixture of water and isopropyl alcohol in a mass ratio of 1:1. After mixing, the mixture is first subjected to ultrasonic crushing for 0.2 hours and then subjected to a planetary ball mill at a speed of 400 rpm for 24 hours. An intermediate solution free of pore-forming agent is obtained.

[0114] (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 a catalyst slurry containing a carbon material pore-forming agent.

[0115] The mass concentration of the catalyst in the slurry is 1%, and the mass ratio of the carbon material to the catalyst is 0.01:1.

[0116] Anode catalyst slurry 2:

[0117] like Figure 1 As shown, the preparation method of the slurry includes:

[0118] (1) An intermediate solution is prepared according to 5% by mass of Ir black catalyst, 5% by mass of perfluorosulfonic acid resin solution (mass concentration is 20%) and 90% by mass of solvent. The perfluorosulfonic acid resin is a commercial resin with an equivalent weight of about 1000, and the solvent is a mixture of water and isopropyl alcohol in a mass ratio of 4:1. That is, 5.0 g of Ir black catalyst and 5.0 g of perfluorosulfonic acid resin solution (mass concentration is 20%) are weighed and added to 90 g of a mixture of water and isopropyl alcohol in a mass ratio of 4:1. After mixing, the mixture is first subjected to ultrasonic crushing for 0.2 hours and then subjected to a planetary ball mill at a speed of 400 rpm for 14 hours. An intermediate solution free of pore-forming agent is obtained.

[0119] (2) 0.5 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 800 rpm for 20 min using a magnetic stirrer to obtain a catalyst slurry containing a carbon material pore-forming agent.

[0120] The mass concentration of the catalyst in the slurry is 5%, and the mass ratio of the carbon material to the catalyst is 0.1:1.

[0121] Anode catalyst slurry 3:

[0122] like Figure 1 As shown, the preparation method of the slurry includes:

[0123] (1) According to the mass percentage of 5% IrO x The intermediate solution is prepared by mixing 7% perfluorosulfonic acid resin solution (mass concentration is 20%) and 88% solvent. The perfluorosulfonic acid resin is a commercial resin with an equivalent weight of about 1000, and the solvent is a mixture of water and ethanol with a mass ratio of 9:1. That is, weigh 5.0g IrO xThe catalyst and 7.0 g of a 20% perfluorosulfonic acid resin solution were added to 88 g of a 9:1 mixture of water and ethanol. 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.

[0124] (2) 0.25 g of carbon powder XC-72 as a carbon material pore-forming agent was added to the intermediate solution of (1), and stirred at 500 rpm for 20 min using a magnetic stirrer to obtain a catalyst slurry containing a carbon material pore-forming agent.

[0125] 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.

[0126] Anode catalyst slurry 4:

[0127] like Figure 1 As shown, the preparation method of the slurry includes:

[0128] (1) According to the mass percentage of 12% Ir-based catalyst, wherein Ir black: IrO x The mass ratio of 1:3, 15% perfluorosulfonic acid resin solution (mass concentration is 20%) and 73% solvent are used to prepare the intermediate solution. The perfluorosulfonic acid resin is a commercial resin with an equivalent weight of about 1000, and the solvent is a mixture of water and isopropanol with a mass ratio of 1:9. That is, 3.0g of Ir black catalyst and 9.0g of IrO are weighed. 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.

[0129] (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 a catalyst slurry containing a carbon material pore-forming agent.

[0130] The mass concentration of the catalyst in the slurry is 12%, and the mass ratio of the carbon material to the catalyst is 0.1:1.

[0131] Anode catalyst slurry 5:

[0132] like Figure 1 As shown, the preparation method of the slurry includes:

[0133] (1) According to the mass percentage of 20% Ir-based catalyst, Ir black: IrO xThe intermediate solution is prepared by mixing 20% perfluorosulfonic acid resin solution (mass concentration is 20%) and 60% solvent in a mass ratio of 3:1. The perfluorosulfonic acid resin is a commercial resin with an equivalent weight of about 1000, and the solvent is a mixture of water and isopropyl alcohol in a mass ratio of 7:3. That is, 5.0g of Ir black catalyst and 15.0g of IrO x 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 a pore-forming agent-free anode catalyst slurry.

[0134] (2) 2.6 g of graphene TG1000 as a carbon material pore-forming agent was added to the anode catalyst slurry without a pore-forming agent in (1), and the mixture was stirred at 700 rpm for 30 min using a magnetic stirrer to obtain a cathode catalyst slurry containing a carbon material pore-forming agent.

[0135] The mass concentration of the catalyst in the slurry is 20%, and the mass ratio of the carbon material to the catalyst is 0.13:1.

[0136] Anode catalyst slurry 6:

[0137] like Figure 1 As shown, the preparation method of the slurry includes:

[0138] (1) According to the mass percentage of 4% IrO x The intermediate solution is prepared by mixing 6% perfluorosulfonic acid resin solution (mass concentration is 20%) and 90% solvent. The perfluorosulfonic acid resin is a commercial resin with an equivalent weight of about 1000, and the solvent is a mixture of water and isopropyl alcohol in a mass ratio of 6:4. 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 a pore-forming agent-free anode catalyst slurry.

[0139] (2) 0.8 g of carbon nanotube FT7000 as a carbon material pore-forming agent was added to the anode catalyst slurry without a pore-forming agent in (1), and the mixture was stirred at 600 rpm for 15 min using a magnetic stirrer to obtain an anode catalyst slurry containing a carbon material pore-forming agent.

[0140] The mass concentration of the catalyst in the slurry is 4%, and the mass ratio of the carbon material to the catalyst is 0.2:1.

[0141] Cathode catalyst slurry 1:

[0142] The cathode catalyst slurry is prepared by ultrasonically dispersing a mixture of 3% by mass of a Pt / C catalyst, 15% 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 with an equivalent weight of approximately 1000, and the solvent is a mixture of water and ethanol in a mass ratio of 1:1. Specifically, 3.0 g of the Pt / C catalyst and 15.0 g of a perfluorosulfonic acid resin solution (with a mass concentration of 20%) are weighed and added to 90 g of a 1:1 mixture of water and ethanol. After mixing, the mixture is ultrasonically dispersed to prepare the cathode catalyst slurry.

[0143] Cathode catalyst slurry 2:

[0144] like Figure 1 As shown, the preparation method of the slurry includes:

[0145] (1) An intermediate solution is prepared according to 2% by mass of a Pt black catalyst, 3% of a perfluorosulfonic acid resin solution (mass concentration is 20%), and 95% of a solvent. The perfluorosulfonic acid resin is a commercial resin with an equivalent weight of about 1000, and the solvent is a mixture of water and isopropyl alcohol in a mass ratio of 3:7. Specifically, 2.0 g of a Pt black catalyst and 3.0 g of a perfluorosulfonic acid resin solution (mass concentration is 20%) are weighed and added to 95 g of a mixture of water and isopropyl alcohol in a mass ratio of 3:7. After mixing, the mixture is first subjected to ultrasonic crushing for 3 hours, and then subjected to a planetary ball mill at a speed of 400 rpm for 2 hours. A cathode catalyst slurry free of a pore-forming agent is obtained.

[0146] (2) Add 0.2 g of activated carbon Black Pearl 2000 cathode catalyst slurry to the intermediate solution without pore-forming agent in (1), and stir the mixture 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 slurry is 2%, and the mass ratio of the carbon material to the catalyst is 0.1:1.

[0148] Cathode catalyst slurry 3:

[0149] like Figure 1 As shown, the preparation method of the slurry includes:

[0150] (1) An intermediate solution is prepared according to 4% by mass of a Pt black catalyst, 6% of a perfluorosulfonic acid resin solution (mass concentration is 20%), and 90% of a solvent. The perfluorosulfonic acid resin is a commercial resin with an equivalent weight of about 1000, and the solvent is a mixture of water and isopropanol in a mass ratio of 3:7. Specifically, 4.0 g of a Pt black catalyst and 6.0 g of a perfluorosulfonic acid resin solution (mass concentration is 20%) are weighed and added to 90 g of a mixture of water and isopropanol in a mass ratio of 3:7. After mixing, the mixture is first subjected to ultrasonic crushing for 3 hours, and then subjected to a planetary ball mill at a speed of 400 rpm for 2 hours. A cathode catalyst slurry free of a pore-forming agent is obtained.

[0151] (2) Add 0.48 g of activated carbon Black Pearl 2000 cathode catalyst slurry to the intermediate solution without pore-forming agent in (1), and stir the mixture at 600 rpm for 15 min using a magnetic stirrer to obtain a cathode catalyst slurry containing a carbon material pore-forming agent.

[0152] The mass concentration of the catalyst in the slurry is 4%, and the mass ratio of the carbon material to the catalyst is 0.12:1.

[0153] Cathode catalyst slurry 4:

[0154] like Figure 1 As shown, the preparation method of the slurry includes:

[0155] (1) An intermediate solution is prepared according to 4% by mass of a Pt black catalyst, 6% of a perfluorosulfonic acid resin solution (mass concentration is 20%), and 90% of a solvent. The perfluorosulfonic acid resin is a commercial resin with an equivalent weight of about 1000, and the solvent is a mixture of water and isopropanol in a mass ratio of 3:7. Specifically, 4.0 g of a Pt black catalyst and 6.0 g of a perfluorosulfonic acid resin solution (mass concentration is 20%) are weighed and added to 90 g of a mixture of water and isopropanol in a mass ratio of 3:7. After mixing, the mixture is first subjected to ultrasonic crushing for 3 hours, and then subjected to a planetary ball mill at a speed of 400 rpm for 2 hours. A cathode catalyst slurry free of a pore-forming agent is obtained.

[0156] (2) Add 0.8 g of carbon nanotube FT9000 cathode catalyst slurry to the intermediate solution without pore-forming agent in (1), and stir the mixture at 600 rpm for 15 min using a magnetic stirrer to obtain a cathode catalyst slurry containing a carbon material pore-forming agent.

[0157] 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.

[0158] Example 1

[0159] This embodiment provides a membrane electrode, which includes two anode catalytic sublayers and a single cathode catalytic layer.

[0160] The preparation method of the membrane electrode comprises:

[0161] 1. Preparation of anode catalyst layer: Using ultrasonic spraying method, 5 parts of anode catalyst slurry 1 and 1 part of anode catalyst slurry 2 were sprayed on one side of the proton exchange membrane in sequence under the condition of 95°C on a vacuum heating plate, and hot pressed to obtain an anode catalyst loading of 2.0 mg / cm 2 That is, the anode catalyst slurry 1 is first sprayed on the surface of the proton exchange membrane, and the anode catalyst slurry 2 is then sprayed on the surface of the sublayer formed by the anode catalyst slurry 1.

[0162] 2. Preparation of cathode catalyst layer: Using ultrasonic spraying method, the cathode catalyst slurry 1 was sprayed on the other side of the proton exchange membrane at 95°C on a vacuum heating plate, and hot pressed to obtain a cathode catalyst loading of 0.5 mg / cm 2 cathode catalyst layer.

[0163] 3. Preparation of membrane electrode: Cover the cathode gas diffusion layer and the anode gas diffusion layer on both sides of the proton exchange membrane with the cathode and anode catalyst layers respectively, and install them on the membrane electrode test bench. Pass deionized water into the anode catalyst layer side, turn on the power, apply a 1.5V positive voltage on the anode side, maintain it for 24 hours, and remove the carbon material in the anode catalyst layer. Remove the gas diffusion layer to obtain the activated proton exchange membrane water electrolysis membrane electrode AA1, the structure is as follows Figure 2 shown.

[0164] Example 2

[0165] This embodiment provides a membrane electrode, which includes three anode catalytic sublayers and a single cathode catalytic layer.

[0166] The preparation method of the membrane electrode comprises:

[0167] 1. Preparation of anode catalyst layer: Using ultrasonic spraying method, 1 part of anode catalyst slurry 3, 1 part of anode catalyst slurry 4 and 1 part of anode catalyst slurry 5 were sprayed on one side of the proton exchange membrane in sequence under the condition of 95°C on a vacuum hot plate, and hot pressed to obtain an anode catalyst loading of 2.0 mg / cm 2 That is, anode catalyst slurry 3 is first sprayed on the surface of the proton exchange membrane, and anode catalyst slurry 4 is then sprayed on the surface of the sublayer formed by anode catalyst slurry 3. Anode catalyst slurry 5 is then sprayed on the surface of the sublayer formed by anode catalyst slurry 4.

[0168] 2. Preparation of cathode catalyst layer: Using ultrasonic spraying method, the cathode catalyst slurry 1 was sprayed on the other side of the proton exchange membrane at 95°C on a vacuum heating plate, and hot pressed to obtain a cathode catalyst loading of 0.5 mg / cm 2cathode catalyst layer.

[0169] 3. Preparation of membrane electrode: Cover the cathode gas diffusion layer and the anode gas diffusion layer on both sides of the proton exchange membrane with the cathode and anode catalyst layers respectively, and install them on the membrane electrode test bench. Pass deionized water into the anode catalyst layer side, turn on the power, apply a 1.5V positive voltage on the anode side, maintain it for 24 hours, and remove the carbon material in the anode catalyst layer. Remove the gas diffusion layer to obtain the activated proton exchange membrane water electrolysis membrane electrode AA2, the structure of which is as follows: Figure 2 shown.

[0170] Example 3

[0171] This embodiment provides a membrane electrode, which includes four anode catalytic sublayers and a single cathode catalytic layer.

[0172] The preparation method of the membrane electrode comprises:

[0173] 1. Preparation of anode catalyst layer: Using ultrasonic spraying method, 4 parts of anode catalyst slurry 3, 1.5 parts of anode catalyst slurry 4, 1 part of anode catalyst slurry 5 and 5 parts of anode catalyst slurry 6 were sprayed on one side of the proton exchange membrane in sequence under the condition of 95°C in a vacuum heating plate, and hot pressed to obtain an anode catalyst loading of 2.0 mg / cm 2 anode catalyst layer.

[0174] That is, anode catalyst slurry 3 is first sprayed onto the surface of the proton exchange membrane, and anode catalyst slurry 4 is then sprayed onto the surface of the sublayer formed by anode catalyst slurry 3. Anode catalyst slurry 5 is then sprayed onto the surface of the sublayer formed by anode catalyst slurry 4. Anode catalyst slurry 6 is then sprayed onto the surface of the sublayer formed by anode catalyst slurry 5.

[0175] 2. Preparation of cathode catalyst layer: Using ultrasonic spraying method, the cathode catalyst slurry 1 was sprayed on the other side of the proton exchange membrane at 95°C on a vacuum heating plate, and hot pressed to obtain a cathode catalyst loading of 0.5 mg / cm 2 cathode catalyst layer.

[0176] 3. Preparation of membrane electrode: Cover the cathode gas diffusion layer and the anode gas diffusion layer on both sides of the proton exchange membrane with the cathode and anode catalyst layers respectively, and install them on the membrane electrode test bench. Pass deionized water into the anode catalyst layer side, turn on the power, apply a 1.5V positive voltage on the anode side, maintain it for 24 hours, and remove the carbon material in the anode catalyst layer. Remove the gas diffusion layer to obtain the activated proton exchange membrane water electrolysis membrane electrode AA3, the structure of which is as follows: Figure 2 shown.

[0177] Example 4

[0178] This embodiment provides a membrane electrode, which includes three anode catalytic sublayers and two cathode catalytic sublayers. The preparation method of the membrane electrode includes:

[0179] 1. Preparation of anode catalyst layer: Using ultrasonic spraying method, 1 part of anode catalyst slurry 3, 1 part of anode catalyst slurry 4 and 1 part of anode catalyst slurry 5 were sprayed on one side of the proton exchange membrane in sequence under the condition of 95°C on a vacuum hot plate, and hot pressed to obtain an anode catalyst loading of 2.0 mg / cm 2 anode catalyst layer.

[0180] That is, anode catalyst slurry 3 is first sprayed on the surface of the proton exchange membrane, and anode catalyst slurry 4 is then sprayed on the surface of the sublayer formed by anode catalyst slurry 3. Anode catalyst slurry 5 is then sprayed on the surface of the sublayer formed by anode catalyst slurry 4.

[0181] 2. Preparation of cathode catalyst layer: Using ultrasonic spraying method, 2 parts of cathode catalyst slurry 2 and 1 part of cathode catalyst slurry 3 were sprayed on the other side of the proton exchange membrane in sequence under the condition of 95°C on a vacuum hot plate, and hot pressed to obtain a cathode catalyst loading of 0.5 mg / cm 2 cathode catalyst layer.

[0182] That is, the cathode catalyst slurry 2 is first sprayed onto the surface of the proton exchange membrane, and the cathode catalyst slurry 3 is then sprayed onto the surface of the sublayer formed by the cathode catalyst slurry 2 .

[0183] 3. Preparation of membrane electrode: The cathode gas diffusion layer and the anode gas diffusion layer are covered on both sides of the proton exchange membrane with the cathode and anode catalyst layers respectively, and are installed on the membrane electrode test bench. Deionized water is passed into the anode catalyst layer side, 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 the cathode catalyst layer side, 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 gas diffusion layer is removed to obtain the activated proton exchange membrane water electrolysis membrane electrode AA4, the structure of which is as follows: Figure 3 shown.

[0184] Example 5

[0185] This embodiment provides a membrane electrode, which includes four anode catalytic sublayers and three cathode catalytic sublayers. The preparation method of the membrane electrode includes:

[0186] 1. Preparation of anode catalyst layer: Using ultrasonic spraying method, 4 parts of anode catalyst slurry 3, 1.5 parts of anode catalyst slurry 4, 1 part of anode catalyst slurry 5 and 5 parts of anode catalyst slurry 6 were sprayed on one side of the proton exchange membrane in sequence under the condition of 95°C in a vacuum heating plate, and hot pressed to obtain an anode catalyst loading of 2.0 mg / cm2 anode catalyst layer.

[0187] That is, anode catalyst slurry 3 is first sprayed onto the surface of the proton exchange membrane, and anode catalyst slurry 4 is then sprayed onto the surface of the sublayer formed by anode catalyst slurry 3. Anode catalyst slurry 5 is then sprayed onto the surface of the sublayer formed by anode catalyst slurry 4. Anode catalyst slurry 6 is then sprayed onto the surface of the sublayer formed by anode catalyst slurry 5.

[0188] 2. Preparation of cathode catalyst layer: Using ultrasonic spraying method, 2 parts of cathode catalyst slurry 2, 1 part of cathode catalyst slurry 3 and 1 part of cathode catalyst slurry 4 were sprayed on the other side of the proton exchange membrane in sequence under the condition of 95°C on a vacuum hot plate, and hot pressed to obtain a cathode catalyst loading of 0.5 mg / cm 2 cathode catalyst layer.

[0189] That is, cathode catalyst slurry 2 is first sprayed on the surface of the proton exchange membrane, and cathode catalyst slurry 3 is then sprayed on the surface of the sublayer formed by cathode catalyst slurry 2. Cathode catalyst slurry 4 is then sprayed on the surface of the sublayer formed by cathode catalyst slurry 3.

[0190] 3. Preparation of membrane electrode: The cathode gas diffusion layer and the anode gas diffusion layer are covered on both sides of the proton exchange membrane with the cathode and anode catalyst layers respectively, and are installed on the membrane electrode test bench. Deionized water is passed into the anode catalyst layer side, 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 the cathode catalyst layer side, 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 gas diffusion layer is removed to obtain the activated proton exchange membrane water electrolysis membrane electrode AA5, the structure of which is shown in FIG. Figure 3 shown.

[0191] The membrane electrode structures of Examples 1 to 3 are as follows Figure 2 As shown in Figure 1, the membrane electrode comprises an anode catalyst layer 1, a proton exchange membrane 2, and a cathode catalyst layer 3, which are stacked in sequence. The cathode catalyst layer 3 is a single-layer structure. The anode catalyst layer 1 is composed of a plurality of stacked anode catalyst sublayers 11, each of which has a plurality of pores 4. The porosity of each anode catalyst sublayer 11 increases from the proton exchange membrane 1 outward.

[0192] The membrane electrode structures of Examples 4 and 5 are as follows Figure 3As shown. The membrane electrode comprises an anode catalyst layer 1, a proton exchange membrane 2, and a cathode catalyst layer 3, which are stacked in sequence. The anode catalyst layer 1 is composed of a plurality of stacked anode catalyst sublayers 11, each of which is distributed with a plurality of pores 4. From the proton exchange membrane 1 outward, the porosity of each anode catalyst sublayer 11 increases. The cathode catalyst layer 3 is composed of a plurality of stacked cathode catalyst sublayers 31, each of which is distributed with a plurality of pores 4. From the proton exchange membrane 1 outward, the porosity of each cathode catalyst sublayer 31 increases.

[0193] Comparative Example 1

[0194] This comparative example provides a membrane electrode, the preparation method of which includes:

[0195] 1. Preparation of anode catalyst slurry:

[0196] 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.

[0197] 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.

[0198] The mass concentration of the catalyst in the slurry is 1%.

[0199] 2. Preparation of cathode catalyst slurry:

[0200] 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%.

[0201] 3. Membrane electrode preparation:

[0202] 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 the anode catalyst layer and the cathode catalyst layer; wherein the Pt loading of the membrane electrode cathode was 0.5 mg / cm 2 , the anode Ir loading is 2.0 mg / cm 2 A porous proton exchange membrane water electrolysis membrane electrode D1 is obtained.

[0203] Comparative Example 2

[0204] This comparative example provides a membrane electrode, the preparation method of which includes:

[0205] 1. Preparation of anode catalyst slurry I:

[0206] 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%.

[0207] 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.

[0208] 2. Preparation of anode catalyst slurry II:

[0209] 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%.

[0210] 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.

[0211] 3. Preparation of cathode catalyst slurry I:

[0212] 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%.

[0213] 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.

[0214] 4. Preparation of cathode catalyst slurry II:

[0215] 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%.

[0216] 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.

[0217] 5. Preparation of membrane electrode:

[0218] 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 Pt loading of the porous membrane electrode cathode is 0.5 mg / cm 2 , the anode Ir loading is 2.0 mg / cm 2 Finally, the porous membrane electrode D2 is obtained by hot pressing.

[0219] Comparative Example 3

[0220] This comparative example provides a membrane electrode, the preparation method of which includes:

[0221] 1. Preparation of anode catalyst slurry:

[0222] 1.0 g IrO xThe 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).

[0223] 2. Preparation of cathode catalyst slurry:

[0224] 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.

[0225] 3. Membrane electrode preparation:

[0226] 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 the anode catalyst layer and the cathode catalyst layer; wherein the Pt loading of the membrane electrode cathode was 0.5 mg / cm 2 , the anode Ir loading is 2.0 mg / cm 2 The cathode gas diffusion layer and the anode gas diffusion layer were covered on both sides of the proton exchange membrane with the cathode and anode catalyst layers, respectively, and installed on a 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, thereby obtaining a porous membrane electrode D3.

[0227] Comparative Example 4

[0228] This comparative example provides a membrane electrode, and the preparation method of the membrane electrode is as follows:

[0229] 1. Preparation of anode catalyst slurry:

[0230] (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.

[0231] (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.

[0232] (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.

[0233] 2. Preparation of cathode catalyst slurry:

[0234] 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.

[0235] 3. Membrane electrode preparation:

[0236] 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 Pt loading of the membrane electrode cathode was 0.5 mg / cm 2 , the anode Ir loading is 2.0 mg / cm 2. A porous membrane electrode D4 is obtained.

[0237] Test Case

[0238] This test example provides the catalytic performance test results of the membrane electrodes prepared in the above examples and comparative examples.

[0239] 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.

[0240] Table 1

[0241] serial number Initial operating voltage End working voltage Example 1 1.82V 1.82V Example 2 1.84V 1.84V Example 3 1.83V 1.83V Example 4 1.82V 1.82V Example 5 1.81V 1.81V 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

[0242] 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.

Claims

1. A membrane electrode, comprising an anode catalyst layer, a proton exchange membrane, and a cathode catalyst layer stacked in sequence; in, The anode catalyst layer includes two or more stacked anode catalyst sublayers; the porosity of each anode catalyst sublayer increases from the proton exchange membrane outward; each anode catalyst sublayer is formed by an anode catalyst slurry, and the preparation method of the anode catalyst slurry includes method a or method b: Method a: mixing an anode catalyst, a resin, and a solvent to obtain an anode catalyst slurry; Method b: 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 comprises 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; When the anode catalytic sublayer is the sublayer with the shortest distance from the proton exchange membrane, the preparation method of the anode catalyst slurry corresponding to the anode catalytic sublayer is method a or method b; When the anode catalytic sublayer is not the sublayer with the shortest distance from the proton exchange membrane, the preparation method of the anode catalyst slurry corresponding to the anode catalytic sublayer is method b.

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

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

1.

4. The membrane electrode according to claim 1, wherein: In method a and method b, the mass content of the anode catalyst in the anode catalyst slurry is 1%-20%, preferably 5%-15%.

5. The membrane electrode according to claim 1, wherein: In method a and method b, in the anode catalyst slurry, the mass ratio of the resin to the anode catalyst is 2-10:10, preferably 2-5:

10.

6. The membrane electrode according to claim 1, wherein: In method b, 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: In method a and method b: The mixing process of the anode catalyst, resin and solvent includes: mixing the catalyst, resin and solvent and uniformly dispersing them; Preferably, the mixing process of the anode catalyst, resin and solvent comprises: subjecting the mixture of the catalyst, resin and solvent to ultrasonic treatment and / or ball milling treatment; 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 anode catalyst layer includes 2-5 anode catalyst sub-layers.

9. The membrane electrode according to claim 1 or 8, wherein: Any two anode catalyst sublayers are respectively recorded as sublayer A and sublayer B, wherein sublayer A is formed by anode catalyst slurry A and sublayer B is formed by anode catalyst slurry B; When the porosity of sublayer B is greater than that of sublayer A, and anode catalyst slurry A and anode catalyst slurry B respectively contain a first pore former: The particle size of the first pore-forming agent in the anode catalyst slurry B is larger than the particle size of the first pore-forming agent in the anode catalyst slurry A; And / or, the mass ratio of the first pore former in anode catalyst slurry B to the anode catalyst in the slurry is greater than the mass ratio of the first pore former in anode catalyst slurry A to the anode catalyst in the slurry.

10. The membrane electrode according to claim 1, wherein: The cathode catalyst layer includes 1 to 5 stacked cathode catalyst sub-layers.

11. The membrane electrode according to claim 10, wherein: The cathode catalytic sublayers are respectively formed of cathode catalyst slurries, wherein the cathode catalyst slurries include cathode catalysts, resins and solvents; When the cathode catalyst has one cathode catalytic sublayer, the cathode catalyst includes a Pt / C catalyst and / or a Pt black catalyst; When the cathode catalyst has two or more cathode catalytic sub-layers, the cathode catalyst includes a Pt black catalyst.

12. The membrane electrode according to claim 11, wherein: The mass content of the cathode catalyst in the cathode catalyst layer is 0.1-2.0 mg / cm 2 .

13. The membrane electrode according to claim 11, wherein: The preparation method of the cathode catalyst slurry includes method c or method d: Method c comprises: mixing a cathode catalyst, a resin, and a solvent to obtain a cathode catalyst slurry; Method d comprises: 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 comprises 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; When the cathode catalytic sublayer is the sublayer with the shortest distance from the proton exchange membrane, the preparation method of the cathode catalyst slurry corresponding to the cathode catalytic sublayer is method c or method d; When the cathode catalytic sublayer is not the sublayer with the shortest distance from the proton exchange membrane, the preparation method of the cathode catalyst slurry corresponding to the cathode catalytic sublayer is method d; In method d, the cathode catalyst includes a Pt black catalyst.

14. The membrane electrode according to claim 13, wherein: In the cathode catalyst slurry, the mass ratio of the second pore-forming agent to the cathode catalyst is 0.01:1-0.2:

1.

15. The membrane electrode according to claim 13, wherein: When the cathode catalytic layer includes two or more stacked cathode catalytic sub-layers, the porosity of each cathode catalytic sub-layer increases from the proton exchange membrane outward.

16. The membrane electrode according to claim 15, wherein: Any two cathode catalyst sublayers are respectively recorded as sublayer C and sublayer D, wherein sublayer C is formed by cathode catalyst slurry C and sublayer D is formed by cathode catalyst slurry D; When the porosity of sublayer D is greater than that of sublayer C, and cathode catalyst slurry C and cathode catalyst slurry D respectively contain a second pore former: The particle size of the second pore-forming agent in the cathode catalyst slurry D is larger than the particle size of the second pore-forming agent in the cathode catalyst slurry C; And / or, the mass ratio of the second pore former in cathode catalyst slurry D to the cathode catalyst in the slurry is greater than the mass ratio of the second pore former in cathode catalyst slurry C to the cathode catalyst in the slurry.

17. The membrane electrode according to claim 1 or 13, wherein: The particle size of the carbon material is 7 nm to 2 μm, preferably 20 nm to 200 nm.

18. The membrane electrode according to claim 1 or 13, 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 includes one or a combination of two or more of activated carbon, graphite powder, and carbon nanotubes.

19. The method for preparing the membrane electrode according to any one of claims 1 to 18, 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.

20. An electrochemical device comprising the membrane electrode according to any one of claims 1 to 18; 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 1-18.

21. A method for producing hydrogen by electrolyzing water, the method being carried out in the electrochemical device according to claim 20.

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