Alkaline electrolytic water hydrogen production composite diaphragm as well as preparation method and application thereof

Abstract

The invention provides an alkaline electrolytic water hydrogen production composite diaphragm as well as a preparation method and application thereof. The composite diaphragm comprises a diaphragm compact layer, a grid support body is embedded in the diaphragm compact layer, and the diaphragm compact layer comprises organic polymer resin and inorganic nanoparticles; the friction-resistant smooth layer is laminated on at least one side of the diaphragm compact layer, and the friction-resistant smooth layer comprises the organic polymer resin and graphite. The diaphragm provided by the invention has relatively low surface friction coefficient, mechanical stability and durability, meanwhile, the diaphragm also has relatively low surface resistance and relatively high conductivity, and the water electrolysis device prepared by adopting the diaphragm has relatively high water electrolysis efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrolysis hydrogen production devices, and in particular to an alkaline water electrolysis hydrogen production composite diaphragm and a preparation method and application thereof. Background Art

[0002] As one of the key technologies for clean energy production, the alkaline water electrolysis hydrogen production system produces high-purity hydrogen and oxygen through the electrochemical decomposition of alkaline electrolyte aqueous solutions. The core structural unit of this technology system is usually composed of a modular combination of several electrolyzers, and its operating efficiency is closely related to the material properties and structural design of the core components. A typical electrolysis unit usually contains the following core elements: a water electrolysis reaction chamber, an alkaline electrolyte medium, a three-dimensional porous electrode structure, an ion transport diaphragm, and a composite conductive system. When a DC electric field is applied to the electrodes on both sides of the diaphragm, a hydrogen evolution reaction occurs on the cathode surface, while an oxygen evolution reaction occurs on the anode, thereby achieving efficient water decomposition.

[0003] During system operation, the ion-conducting diaphragm, a key functional component, has multiple tasks: establishing an effective ion transport channel and preventing cross-penetration of generated gases. Furthermore, under the dynamic operating conditions of the electrolyzer, frictional contact exists between the diaphragm and the electrodes, leading to coating delamination under long-term mechanical friction. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the prior art to a certain extent. To this end, one object of the present invention is to provide an alkaline water electrolysis hydrogen production composite diaphragm and its preparation method and application.

[0005] In a first aspect of the present invention, the present invention provides an alkaline water electrolysis hydrogen production composite diaphragm, which comprises: A diaphragm dense layer, wherein a grid support is embedded in the diaphragm dense layer, and the diaphragm dense layer comprises an organic polymer resin and inorganic nanoparticles; A friction-resistant smooth layer is stacked on at least one side of the diaphragm dense layer, and the friction-resistant smooth layer comprises the organic polymer resin and graphite.

[0006] The alkaline water electrolysis hydrogen production composite membrane provided by the present invention comprises a dense membrane layer and a friction-resistant smooth layer. The friction-resistant smooth layer is laminated on at least one side of the dense membrane layer and comprises an organic polymer resin and graphite. The graphite sheets have weak interlayer bonding, so during friction, interlayer sliding replaces direct friction between the membrane and the electrode, reducing the friction coefficient. Polar groups on the graphite surface absorb the electrolyte to form a water film, isolating solid contact and reducing wear. The organic polymer resin stabilizes the graphite and cushions vibrations. The graphite acts as a wear-resistant filler, reducing matrix loss and providing long-term alkali resistance and stability. A grid support is embedded within the dense membrane layer, ensuring excellent mechanical properties without compromising ion permeability. The dense layer and the smooth layer form a synergistic effect, with a gradient hardness design absorbing frictional stress and stabilizing the structure to prevent graphite shedding. Furthermore, the ionic groups in the dense layer work in concert with the hydroxyl groups in the smooth layer to directional guide OH⁻ ions, inhibiting cation migration and improving conductivity. This effectively reduces membrane resistance, improves conductivity, and, in turn, enhances water electrolysis efficiency.

[0007] In some embodiments of the present invention, the surface friction coefficient of the friction-resistant smooth layer is 0.2-0.3. Studies have shown that within this friction coefficient range, the friction loss between the diaphragm and the electrode can be effectively reduced.

[0008] In some embodiments of the present invention, the ionic resistance of the composite membrane is 0.28-0.32Ω.cm 2 The composite membrane has low ionic resistance.

[0009] In some embodiments of the present invention, in the dense layer of the diaphragm, the mass ratio of the organic polymer resin, the inorganic nanoparticles and the grid support is (50-60): (30-40): (2-20). Controlling the mass ratio of the organic polymer resin, the inorganic nanoparticles and the grid support within the above range can enhance the mechanical strength and dimensional stability of the membrane while ensuring the density and flexibility of the membrane. Specifically, an appropriate amount of inorganic nanoparticles can form a stable dispersed phase in the resin matrix, improving the structural integrity and anti-swelling ability of the ion channel; and an appropriate proportion of the grid support helps to construct a three-dimensional support framework, inhibiting deformation of the membrane layer due to hydration or cross-linking stress, thereby significantly improving the overall durability and service life of the diaphragm.

[0010] In some embodiments of the present application, the mass ratio of the organic polymer resin and the graphite in the friction-resistant smooth layer is (60-80):(20-40). Controlling the mass ratio of the organic polymer resin and the graphite within the above range can ensure the lubricity and friction resistance of the film surface while maintaining the film-forming property and structural continuity of the material. Specifically, the introduction of an appropriate amount of graphite endows the film layer with excellent surface slip properties and wear resistance, while the dominant proportion of the polymer resin ensures the flexibility and adhesion of the coating. The coordinated proportion of the two can prevent graphite aggregation or shedding, avoid the appearance of surface roughness or cracks, and thus achieve the best balance between durability and surface performance.

[0011] Further, the mass fraction of graphite in the friction-resistant smooth layer is greater than the mass fraction of the grid support in the dense layer of the diaphragm. The mass fraction of graphite in the friction-resistant smooth layer is less than the sum of the mass fractions of the inorganic nanoparticles and the grid support in the dense layer of the diaphragm. The mass fraction of the organic polymer resin in the dense layer of the diaphragm is greater than or equal to 50%, and the mass fraction of the organic polymer resin in the friction-resistant smooth layer is greater than or equal to 50%.

[0012] In some embodiments of the present application, the thickness of the dense layer of the diaphragm is 200-400 μm. For example, the thickness is 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, or a range between any two of the above values. Controlling the thickness of the dense layer of the diaphragm within the range of 200-400 μm can reduce the ion resistance of the diaphragm and improve the electronic conductivity.

[0013] In some embodiments of the present application, the thickness of the grid support is 50-100 μm. For example, the thickness is 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or a range between any two of the above values. Controlling the thickness of the grid support to be 50-100 μm can effectively enhance the mechanical properties of the diaphragm.

[0014] In some embodiments of the present application, the thickness of the friction-resistant smooth layer is 50-100 μm. For example, the thickness is 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or a range between any two of the above values. Controlling the thickness of the friction-resistant smooth layer to be 50-100 μm can maintain a relatively low friction coefficient while having a relatively low surface resistance.

[0015] In some embodiments of the present application, the thickness of the diaphragm is 300-600 μm, preferably 400-600 μm. Controlling the thickness of the diaphragm within the above range can enable the diaphragm to maintain good air tightness and low surface resistance.

[0016] In some embodiments of the present invention, the average pore size of the friction-resistant smooth layer is less than 0.01 μm, for example, the average pore size of the friction-resistant smooth layer is 0.008 μm, 0.006 μm, 0.004 μm, 0.002 μm, 0.001 μm, etc.

[0017] In some embodiments of the present invention, the average pore size of the dense layer of the diaphragm is 0.01 μm-0.2 μm. For example, the average pore size of the dense layer of the diaphragm is 0.01 μm, 0.05 μm, 0.1 μm, 0.12 μm, 0.15 μm, 0.18 μm, 0.2 μm, etc., or a range between any two of the above values.

[0018] In some embodiments of the present invention, the average pore size of the grid support is 500μm-1000μm. For example, the average pore size of the grid support is 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, etc., or a range between any two of the above values. By controlling the average pore size of the grid support within the above range, the continuity and permeability of the ion or molecular channels can be ensured while ensuring sufficient mechanical support strength. Smaller pore sizes help to improve the density and support uniformity of the diaphragm structure, inhibit local expansion or material leakage; and appropriately larger pore sizes are beneficial to reducing liquid transfer resistance and enhancing reactant diffusion efficiency. By precisely controlling the pore size, the optimal balance between the mechanical stability and mass transfer performance of the membrane material can be achieved, thereby improving the operating efficiency and service life of the overall electrochemical system.

[0019] In some embodiments of the present invention, the organic polymer resin is selected from one or more of polyetherethersulfone, polyetherketone, polyetheretherketone, polyarylethersulfone, and polyaryletherketone.

[0020] Furthermore, the organic polymer resin in the friction-resistant smooth layer and the dense layer of the diaphragm is the same.

[0021] In some embodiments of the present invention, the material of the grid support is selected from one or more of polypropylene, polyethylene, aramid, polyphenylene sulfide, and polyarylate.

[0022] In some embodiments of the present invention, the inorganic nanoparticles include one or more of zirconium dioxide, titanium dioxide, silicon dioxide, or aluminum oxide, preferably zirconium dioxide.

[0023] In some embodiments of the present invention, the particle size of the inorganic nanoparticles is 20 nm-40 nm.

[0024] In some embodiments of the present invention, the graphite includes one or more of flake graphite, block graphite or earthy graphite, preferably flake graphite.

[0025] In a second aspect of the present invention, the present invention provides a method for preparing the above-mentioned alkaline water electrolysis hydrogen production composite membrane, which comprises: Applying a first slurry comprising an organic polymer resin and inorganic nanoparticles on a grid support, and wrapping a first liquid film on the grid support after the slurry is completely poured; applying a second slurry comprising the organic polymer resin and graphite onto the first liquid film on at least one side of the grid support, and then pre-evaporating the slurry to form a prefabricated diaphragm; The prefabricated diaphragm is placed in an organic solvent water-based coagulation medium for phase inversion.

[0026] The method provided by the present invention triggers a phase separation mechanism by means of a replacement process between a solvent and a non-solvent, and ultimately produces a friction-resistant alkaline water electrolysis diaphragm having a continuous through-pore network.

[0027] In some embodiments of the present invention, the pre-evaporation temperature is 60-90° C., and the pre-evaporation time is 6 min-12 min.

[0028] In some embodiments of the present invention, the mass fraction of the organic solvent in the organic solvent water-based coagulation medium is 10-50%.

[0029] Furthermore, the organic solvent in the organic solvent water-based coagulation medium is selected from one or more of N-methylpyrrolidone, N,N-dimethylformamide or dimethyl sulfoxide.

[0030] In some embodiments of the present invention, the organic polymer resin and the inorganic nanoparticles are dissolved in an organic solvent to form a first slurry, wherein the first slurry has a solid content of 10-40%. Furthermore, the organic solvent is selected from one or more of N-methylpyrrolidone, N,N-dimethylformamide, or dimethyl sulfoxide.

[0031] In some embodiments of the present invention, the organic polymer resin and graphite are dissolved in an organic solvent to form a second slurry, wherein the second slurry has a solid content of 20-50%. Furthermore, the organic solvent is selected from one or more of N-methylpyrrolidone, N,N-dimethylformamide, or dimethyl sulfoxide.

[0032] Furthermore, the organic solvent in the first slurry, the organic solvent in the second slurry, and the organic solvent in the organic solvent water-based coagulation medium are the same.

[0033] In some embodiments of the present invention, the grid support body is completely immersed in the first slurry, and the first slurry film liquid on one side of the grid support body is scraped flat to prepare a wet diaphragm; then the second slurry is spread on the scraped first slurry film liquid and scraped flat, and then the diaphragm is immersed in a mixed solution of water and organic solvent to form a diaphragm with a porous structure through phase inversion.

[0034] In some embodiments of the present invention, a membrane manufacturing device (eg, MSK-AFA-L1000 doctor blade coater) is used for preparation.

[0035] In some embodiments of the present invention, a flat scraper is used to scrape the membrane liquid on one side of the grid support flat.

[0036] In some embodiments of the present invention, membranes with different thicknesses are prepared by controlling the gap between the flat blades.

[0037] In a third aspect, the present invention provides an alkaline water electrolysis hydrogen production device, comprising the alkaline water electrolysis hydrogen production composite diaphragm described above or the alkaline water electrolysis hydrogen production composite diaphragm prepared using the above method. Thus, the alkaline water electrolysis hydrogen production device has a high electrolysis rate.

[0038] The present invention has at least the following beneficial effects: The composite diaphragm of the present invention includes a diaphragm dense layer and a friction-resistant smooth layer. The friction-resistant smooth layer is stacked on at least one side of the diaphragm dense layer. The friction-resistant smooth layer includes an organic polymer resin and graphite. The addition of graphite to the friction-resistant smooth layer can reduce the friction coefficient of the diaphragm, thereby effectively improving the friction resistance of the diaphragm and effectively reducing the friction loss between the diaphragm and the electrode. At the same time, the polar groups on the surface of the graphite adsorb the electrolyte to form a water film, isolating solid contact and reducing wear. The organic polymer resin fixes the graphite and buffers vibrations. The graphite acts as a wear-resistant filler to reduce matrix loss and is alkali-resistant and stable for a long time. The present invention uses a grid support body to enhance the mechanical strength of the diaphragm, thereby effectively improving the overall stability of the diaphragm without affecting the ion permeability. The diaphragm dense layer and the friction-resistant smooth layer form a synergistic effect. The gradient hardness design absorbs friction stress and stabilizes the structure to prevent graphite from falling off. In addition, the ionic groups in the dense layer cooperate with the hydroxyl groups in the graphite in the smooth layer to directionally guide OH⁻ ions, inhibit cation migration, reduce diaphragm resistance, and improve conductivity. The diaphragm provided by the present invention has excellent air tightness, durability, electrical insulation and electrical conductivity, and the water electrolysis device prepared by using the diaphragm has high water electrolysis efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 is a schematic structural diagram of the composite diaphragm provided in Example 2 of the present invention; Figure 2is a composite diaphragm cross-section electron micrograph provided by the embodiment 2 of the present application. DETAILED DESCRIPTION

[0041] All other embodiments obtained by a person of ordinary skill in the art without making creative efforts based on the embodiments in the present application fall within the scope of protection of the present application. The present application is described below with reference to specific embodiments, and it should be noted that these embodiments are merely descriptive and do not limit the present application in any way.

[0042] Embodiment 1 The present embodiment provides a composite diaphragm composed of a diaphragm dense layer and a friction-resistant smooth layer laminated on one side of the diaphragm dense layer, i.e., a 2-layer film structure composed of the laminated diaphragm dense layer and friction-resistant smooth layer.

[0043] In the diaphragm dense layer, the mass ratio of organic polymer resin (polyether ether sulfone), inorganic nanoparticles (zirconium dioxide, 20 nm) and polypropylene grid support is 55:40:5; the thickness of the diaphragm dense layer is 300 μm, the average pore size of the diaphragm dense layer is 0.05 μm, the average pore size of the polypropylene grid support is 700 μm, and the thickness of the polypropylene grid support is 50 μm.

[0044] In the friction-resistant smooth layer, the mass ratio of organic polymer resin (polyether ether sulfone) and flake graphite is 65:35; the thickness of the friction-resistant smooth layer is 100 μm, and the average pore size of the friction-resistant smooth layer is 0.004 μm.

[0045] The preparation process of the composite diaphragm of the present embodiment is as follows: S1, preparing diaphragm dense layer film solution (first slurry) components: polyether ether sulfone and zirconium dioxide are put into N-methyl pyrrolidone solution and stirred and mixed uniformly, with a solid content of 30%; S2, immersing the polypropylene grid in the diaphragm dense layer film solution stirred and mixed uniformly in S1, and then using a diaphragm manufacturing device (MSK-AFA-L1000 doctor blade coater, same below), using a 400-micron fixed doctor blade to scrape the casting solution on one side of the support flat, to prepare a diaphragm in a mucous state; S3, preparing friction-resistant smooth layer film solution (second slurry) components: polyether ether sulfone and flake graphite are put into N-methyl pyrrolidone solution and stirred and mixed uniformly, with a solid content of 40%; S4, pouring the friction-resistant smooth layer film solution components in S3 on the composite diaphragm in a mucous state in S2, and then using a 600-micron fixed doctor blade to scrape the film solution on one side of the flake graphite flat, to prepare a composite diaphragm in a mucous state; S5. Pre-evaporate the viscous composite membrane in S4 in an oven at 60°C for 5 minutes until the surface viscous membrane solidifies. The composite membrane is then placed in a phase inversion solution at 25°C for phase inversion; the phase inversion solution consists of 80 wt% water and 20 wt% NMP organic solution. The phase inversion time is 10 minutes. During the phase inversion process, the organic polymer resin in the membrane solution solidifies, and the polymer resin and solvent undergo phase separation, thereby forming a porous, friction-resistant alkaline water electrolysis membrane.

[0046] Example 2 This embodiment provides a composite diaphragm, which is composed of a diaphragm dense layer and a first friction-resistant smooth layer and a second friction-resistant smooth layer stacked on both sides of the diaphragm dense layer. That is, the composite diaphragm is a three-layer membrane structure consisting of a stacked first friction-resistant smooth layer, a diaphragm dense layer and a second friction-resistant smooth layer. Figure 1 The diaphragm structure, the specific diaphragm cross-section electron microscope diagram can be referred to Figure 2 .

[0047] In the dense layer of the diaphragm, the mass ratio of organic polymer resin (polyether ether sulfone), inorganic nanoparticles (zirconium dioxide, 20 nm) and polypropylene grid support is 55:40:5; the thickness of the dense layer of the diaphragm is 350 μm, the average pore size of the dense layer of the diaphragm is 0.1 μm, the average pore size of the polypropylene grid support is 800 μm, and the thickness of the polypropylene grid support is 70 μm.

[0048] The mass ratio of organic polymer resin (polyether ether sulfone) to flake graphite in the first friction-resistant smooth layer is 65:35; the thickness of the friction-resistant smooth layer is 100 μm, and the average pore size of the friction-resistant smooth layer is 0.002 μm; The mass ratio of the organic polymer resin (polyether ether sulfone) to the flake graphite in the second friction-resistant smooth layer is 65:35; the thickness of the friction-resistant smooth layer is 100 μm, and the average pore size of the friction-resistant smooth layer is 0.002 μm.

[0049] The preparation process of the composite diaphragm of this embodiment is as follows: S1. Prepare the components of the friction-resistant smooth layer film liquid: put polyetherethersulfone and flake graphite into N-methylpyrrolidone solution and stir to mix evenly, with a solid content of 30%; S2. Using a diaphragm manufacturing device, scrape the friction-resistant smooth layer of film using a 200-micron fixed scraper to produce a viscous diaphragm; S3. Prepare the membrane liquid components of the dense layer of the diaphragm: put polyetherethersulfone and zirconium dioxide into N-methylpyrrolidone solution and stir to mix evenly, with a solid content of 30%; S4, placing a polypropylene mesh on the surface of the viscous membrane in S2, pouring the membrane liquid component of the dense layer of the membrane in S3 onto the polypropylene mesh, and using a 600-micron fixed scraper to flatten the membrane liquid of the dense layer of the membrane to prepare a composite membrane in a viscous state; S5, further pouring the friction-resistant smooth layer membrane liquid component in S1 onto the composite diaphragm in a viscous state in S4, and then scraping it flat with a 700-micron fixed scraper to prepare a three-layer composite diaphragm in a viscous state; S6. Pre-evaporate the viscous composite membrane from S5 in an oven at 60°C for 5 minutes until the surface viscous membrane solidifies. The composite membrane is then placed in a phase inversion solution at 25°C for phase inversion; the phase inversion solution consists of 60 wt% water and 40 wt% NMP organic solution. The phase inversion time is 15 minutes. During the phase inversion process, the organic polymer resin in the membrane solution solidifies, and the polymer resin and solvent undergo phase separation, thereby forming a three-layer porous structure and a friction-resistant alkaline water electrolysis membrane.

[0050] Example 3 This embodiment provides a composite diaphragm, which consists of a diaphragm dense layer and a friction-resistant smooth layer stacked on one side of the diaphragm dense layer, that is, the composite diaphragm has a two-layer membrane structure consisting of the stacked diaphragm dense layer and the friction-resistant smooth layer.

[0051] In the dense layer of the diaphragm, the mass ratio of organic polymer resin (polyaryletherketone), inorganic nanoparticles (zirconium dioxide, 40nm) and polyphenylene sulfide fiber grid support is 60:35:5; the thickness of the dense layer of the diaphragm is 350μm, the average pore size of the dense layer of the diaphragm is 0.12μm, the average pore size of the polyphenylene sulfide fiber grid support is 800μm, and the thickness of the polyphenylene sulfide fiber grid support is 70μm.

[0052] The mass ratio of the organic polymer resin (polyaryletherketone) and the flake graphite in the friction-resistant smooth layer is 70:30; the thickness of the friction-resistant smooth layer is 100 μm, and the average pore size of the friction-resistant smooth layer is 0.002 μm.

[0053] The preparation process of the composite diaphragm of this embodiment is as follows: S1. Prepare the membrane liquid (first slurry) components of the dense layer of the diaphragm: put polyaryletherketone and zirconium dioxide into N-methylpyrrolidone solution and stir to mix evenly, with a solid content of 40%; S2, immersing the polyphenylene sulfide fiber web in the uniformly stirred membrane dense layer solution in S1, and then using a membrane manufacturing device, using a 400-micron fixed scraper to scrape the casting solution on one side of the support to prepare a viscous membrane; S3. Prepare the components of the friction-resistant smooth layer film liquid (second slurry): put polyaryletherketone and flake graphite into N-methylpyrrolidone solution and stir to mix evenly, with a solid content of 40%; S4, pouring the friction-resistant smooth layer film liquid component in S3 onto the composite diaphragm in a mucus state in S2, and then using a 600-micron fixed scraper to scrape the film liquid on one side of the flake graphite flat to prepare a composite diaphragm in a mucus state; S5. Pre-evaporate the viscous composite membrane in S4 in a 70°C oven for 5 minutes until the surface viscous membrane solidifies. The composite membrane is then placed in a phase inversion solution at 25°C for phase inversion; the phase inversion solution consists of 70 wt% water and 30 wt% NMP organic solution. The phase inversion time is 10 minutes. During the phase inversion process, the organic polymer resin in the membrane solution solidifies, and the polymer resin and solvent undergo phase separation, thereby forming a porous, friction-resistant alkaline water electrolysis membrane.

[0054] Example 4 This embodiment provides a composite diaphragm, which consists of a diaphragm dense layer and a first friction-resistant smooth layer and a second friction-resistant smooth layer stacked on both sides of the diaphragm dense layer, that is, the composite diaphragm has a three-layer membrane structure consisting of the stacked first friction-resistant smooth layer, the diaphragm dense layer and the second friction-resistant smooth layer.

[0055] In the dense layer of the diaphragm, the mass ratio of organic polymer resin (polyaryletherketone), inorganic nanoparticles (zirconium dioxide, 40nm) and polyphenylene sulfide fiber grid support is 60:35:5; the thickness of the diaphragm dense layer is 300μm, the average pore size of the diaphragm dense layer is 0.1μm, the average pore size of the polyphenylene sulfide fiber grid support is 700μm, and the thickness of the polyphenylene sulfide fiber grid support is 60μm.

[0056] The mass ratio of the organic polymer resin (polyaryletherketone) to the flake graphite in the first friction-resistant smooth layer is 70:30; the thickness of the friction-resistant smooth layer is 100 μm, and the average pore size of the friction-resistant smooth layer is 0.006 μm; The mass ratio of the organic polymer resin (polyaryletherketone) and flake graphite in the second friction-resistant smooth layer is 70:30; the thickness of the friction-resistant smooth layer is 100 μm, and the average pore size of the friction-resistant smooth layer is 0.004 μm.

[0057] The preparation process of the composite diaphragm of this embodiment is as follows: S1. Prepare the components of the friction-resistant smooth layer film liquid: put polyaryletherketone and flake graphite into N-methylpyrrolidone solution and stir to mix evenly, with a solid content of 20%; S2. Using a diaphragm manufacturing device, scrape the friction-resistant smooth layer of film using a 200-micron fixed scraper to produce a viscous diaphragm; S3. Prepare the membrane liquid components of the dense layer of the diaphragm: put polyaryletherketone and zirconium dioxide into N-methylpyrrolidone solution and stir to mix evenly, with a solid content of 40%; S4, placing the polyphenylene sulfide fiber web on the surface of the viscous membrane stirred evenly in S2, pouring the membrane liquid component of the dense layer of the membrane in S3 onto the polyphenylene sulfide fiber web, and using a 600-micron fixed scraper to flatten the membrane liquid of the dense layer of the membrane to prepare a composite membrane in a viscous state; S5, further pouring the friction-resistant smooth layer membrane liquid component in S1 onto the composite diaphragm in a viscous state in S4, and then scraping it flat with a 700-micron fixed scraper to prepare a three-layer composite diaphragm in a viscous state; S6. Pre-evaporate the viscous composite membrane from S5 in an oven at 70°C for 5 minutes, solidifying the surface viscous membrane. The composite membrane is then placed in a phase inversion solution at 25°C for phase inversion; the phase inversion solution consists of 50 wt% water and 50 wt% NMP organic solution. The phase inversion time is 15 minutes. During the phase inversion process, the organic polymer resin in the membrane solution solidifies, and the polymer resin and solvent undergo phase separation, thereby forming a three-layer porous structure and a friction-resistant alkaline water electrolysis membrane.

[0058] Comparative Example 1 The commercially available separator, ZIRFON PERL UTP 500, was purchased from Agfa-Gevaert.

[0059] Comparative Example 2 The commercially available separator, TORCON® PPS, was purchased from TORAY.

[0060] Comparative Example 3 This comparative example provides a diaphragm. The difference between the diaphragm of comparative example 3 and embodiment 1 is that the diaphragm of comparative example 3 only contains a diaphragm dense layer and has no friction-resistant smooth layer.

[0061] Comparative Example 4 This comparative example provides a diaphragm. The preparation process of the diaphragm of comparative example 4 is as follows: The diaphragm of Comparative Example 4 was prepared using the same raw materials as the composite diaphragm of Example 1. The specific preparation process was as follows: an organic polymer resin (polyetherethersulfone), inorganic nanoparticles (zirconium dioxide, 20 nm), and flake graphite were stirred and uniformly mixed in an N-methylpyrrolidone solution with a solids content of 30%. A polypropylene mesh was then immersed in the mixed solution and smoothed with a fixed scraper to produce a viscous diaphragm. Finally, the viscous composite diaphragm was pre-evaporated in a 60°C oven for 5 minutes to solidify the surface viscous liquid. The composite diaphragm was then placed in a phase inversion solution at 25°C for a phase inversion reaction consisting of 80 wt% water and 20 wt% NMP organic solution. The phase inversion time was 10 minutes. The diaphragm prepared in Comparative Example 4 had the same thickness as the composite diaphragm of Example 1.

[0062] The properties of the separators of Examples and Comparative Examples were measured.

[0063] Performance tests include friction resistance test and voltage and current performance test.

[0064] Friction resistance test: Use a multifunctional micro-friction testing machine to test the friction performance of the film.

[0065] Voltage and current evaluation: The diaphragm was placed in an electrolytic cell unit for electrolysis testing. The electrolyte was a 30% potassium hydroxide aqueous solution, and the temperature was set at 80°C. The anode used nickel felt, the cathode used a hydrogen-producing active cathode, and the current density was set at 0.5A cm -2 , determine the required electrolysis voltage. Performance test results are shown in Table 1.

[0066] Table 1

[0067] As can be seen from Table 1, the friction coefficient of the diaphragm of Example 1-4 is smaller than that of the diaphragm of Comparative Example 1-4. The smaller the friction coefficient, the better the friction resistance of the diaphragm. The ionic resistance of the diaphragm of Example 1-4 is smaller than that of the diaphragm of Comparative Example 1-2. Under the same current, the voltage of the diaphragm of Example 1-4 is lower than that of the diaphragm of Comparative Example 1-2. The ionic resistance of the diaphragm of Example 1-4 is similar to that of the diaphragm of Comparative Example 3-4. Under the same current, the voltage of the diaphragm of Example 1-4 is also similar. However, the friction resistance of the diaphragm of Example 1-4 is better than that of the diaphragm of Comparative Example 3-4, which shows that our method of constructing a friction-resistant diaphragm is very effective.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A composite diaphragm for producing hydrogen by alkaline water electrolysis, characterized in that: include: A diaphragm dense layer, wherein a grid support is embedded in the diaphragm dense layer, and the diaphragm dense layer comprises an organic polymer resin and inorganic nanoparticles; A friction-resistant smooth layer is stacked on at least one side of the diaphragm dense layer, and the friction-resistant smooth layer comprises the organic polymer resin and graphite.

2. The composite diaphragm according to claim 1, characterized in that: In the dense layer of the diaphragm, the mass ratio of the organic polymer resin, the inorganic nanoparticles and the grid support is (50-60): (30-40): (2-20).

3. The composite diaphragm according to claim 1 or 2, characterized in that: The thickness of the dense layer of the diaphragm is 200 μm-400 μm; And / or, the thickness of the grid support is 50 μm-100 μm.

4. The composite diaphragm according to claim 1, characterized in that: In the friction-resistant smooth layer, the mass ratio of the organic polymer resin to the graphite is (60-80):(20-40).

5. The composite diaphragm according to claim 1 or 4, characterized in that: The thickness of the friction-resistant smooth layer is 50 μm-100 μm.

6. The composite diaphragm according to any one of claims 1, 2 and 4, characterized in that: The average pore size of the friction-resistant smooth layer is less than 0.01 μm; and / or, the average pore size of the dense layer of the diaphragm is 0.01 μm-0.2 μm; And / or, the average pore size of the grid support is 500 μm-1000 μm.

7. The composite diaphragm according to any one of claims 1, 2 and 4, characterized in that: The organic polymer resin is selected from one or more of polyetherethersulfone, polyetherketone, polyetheretherketone, polyarylethersulfone and polyaryletherketone; And / or, the material of the grid support is selected from one or more of polypropylene, polyethylene, aramid, polyphenylene sulfide, and polyarylate; and / or, the inorganic nanoparticles include one or more of zirconium dioxide, titanium dioxide, silicon dioxide or aluminum oxide, preferably zirconium dioxide; and / or, the particle size of the inorganic nanoparticles is 20 nm to 40 nm; And / or, the graphite includes one or more of flake graphite, block graphite or earthy graphite, preferably flake graphite.

8. The composite diaphragm according to any one of claims 1, 2 and 4, characterized in that: The surface friction coefficient of the friction-resistant smooth layer of the composite diaphragm is 0.2-0.3; And / or, the ionic resistance of the composite membrane is 0.28-0.32Ω.cm 2 .

9. A method for preparing the composite membrane for producing hydrogen by alkaline water electrolysis according to any one of claims 1 to 8, characterized in that: include: Applying a first slurry comprising an organic polymer resin and inorganic nanoparticles on a grid support, and wrapping a first liquid film on the grid support after the slurry is completely poured; applying a second slurry comprising the organic polymer resin and graphite onto the first liquid film on at least one side of the grid support, and then pre-evaporating the slurry to form a prefabricated diaphragm; placing the prefabricated diaphragm in an organic solvent water-based coagulation medium for phase inversion; Preferably, the pre-evaporation temperature is 60-90°C, and the pre-evaporation time is 6 min-12 min; Preferably, the mass fraction of the organic solvent in the organic solvent water-based coagulation medium is 10-50%.

10. An alkaline water electrolysis hydrogen production device, characterized in that: It comprises the alkaline water electrolysis hydrogen production composite diaphragm according to any one of claims 1 to 8 or the alkaline water electrolysis hydrogen production composite diaphragm prepared by the method according to claim 9.

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