Diaphragm and preparation method thereof, water electrolysis device and application

Abstract

The invention discloses a diaphragm, a preparation method thereof, a water electrolysis device and application. The preparation method of the diaphragm comprises the following steps: forming a liquid membrane of a membrane casting solution on one side surface or two side surfaces of the supporting layer; carrying out phase inversion treatment on the supporting layer with the liquid membrane, curing the liquid membrane, preparing a composite membrane, and putting the composite membrane into an assistant crosslinking solution for assistant crosslinking treatment, so as to prepare the diaphragm, wherein the assistant crosslinking solution comprises an assistant crosslinking agent. According to the diaphragm provided by the invention, by optimizing the preparation process, the interfacial compatibility among all layers of structures of the composite membrane can be optimized by post-treatment of immersing the composite membrane into the assistant crosslinker solution after the preparation of the composite membrane is completed, and the high-temperature-resistant stability of the diaphragm can be improved.

Description

Technical Field

[0001] This application relates to the field of water electrolysis, and in particular to a diaphragm, its preparation method, a water electrolysis device, and its applications. Background Technology

[0002] The excessive use of fossil fuels has led to the depletion of fossil fuel resources, triggering a severe energy crisis and environmental problems. In recent years, clean energy sources such as hydrogen and wind power have been continuously developed. Water electrolysis is a highly efficient and clean hydrogen production technology with a simple process, producing hydrogen with a purity greater than 99.9%. There are three main traditional water electrolysis hydrogen production technologies: alkaline water electrolysis, proton exchange membrane water electrolysis, and solid oxide water electrolysis. Among them, alkaline water electrolysis has been widely used due to its mature technology, low cost, and suitability for large-scale commercial production. For alkaline water electrolysis, the choice of membrane is crucial.

[0003] Traditional diaphragms have poor interfacial compatibility between their various layers, resulting in poor high-temperature stability. Summary of the Invention

[0004] Therefore, in order to improve the heat resistance stability of the diaphragm, it is necessary to provide a composite diaphragm, its preparation method, a water electrolysis device, and its application.

[0005] One embodiment of this application provides a method for preparing a diaphragm, comprising the following steps:

[0006] A liquid film of casting solution is formed on one or both surfaces of the support layer;

[0007] The support layer on which the liquid film is formed is subjected to a phase transformation treatment to solidify the liquid film and prepare a composite film.

[0008] The composite membrane is placed in a cross-linking solution for cross-linking treatment to prepare the separator.

[0009] The crosslinking solution includes a crosslinking agent, which includes one or more of vinyltriethoxysilane, glutaraldehyde, triglycidyl isocyanurate, and polyvinyl alcohol.

[0010] In one embodiment, the crosslinking agent treatment satisfies one or both of the following conditions:

[0011] (1) The mass percentage of the crosslinking agent in the crosslinking solution is 1% to 3%;

[0012] (2) The crosslinking treatment time is 1 min to 5 min;

[0013] (3) The temperature of the crosslinking treatment is 40℃~50℃.

[0014] In one embodiment, the phase transformation process includes gas-phase induced phase transformation and liquid-phase induced phase transformation.

[0015] In one embodiment, the conditions for the gas-phase induced phase transformation satisfy one or both of the following conditions:

[0016] (1) The temperature of the gas-phase induced phase transformation is 25℃~60℃;

[0017] (2) The time for the gas-induced phase transformation is 10s~30s.

[0018] In one embodiment, the conditions for the liquid-induced phase transformation satisfy one or more of the following conditions:

[0019] (1) The liquid phase-induced phase transformation is carried out in a coagulation liquid, wherein the coagulation liquid comprises one or more of isopropanol, water and N-methylpyrrolidone;

[0020] (2) The temperature for the liquid-induced phase transformation is 25℃~30℃;

[0021] (3) The liquid-induced phase transformation time is 10 min to 15 min.

[0022] In one embodiment, the casting solution comprises 14 to 20 parts by weight of a polymer, 2 to 3 parts by weight of a pore-forming agent, and 46.6 to 64 parts by weight of inorganic nanomaterials.

[0023] In one embodiment, one or more of the following conditions are met:

[0024] (1) The polymer includes one or more of polysulfone, polyethersulfone, polyphenylene sulfone, polyphenylsulfone, and polyetheretherketone;

[0025] (2) The weight-average molecular weight of the polymer is 56,000 to 75,000;

[0026] (3) The particle size of the inorganic nanomaterial is 40nm~100nm;

[0027] (3) The thickness of the liquid film of the casting solution is 200μm to 300μm;

[0028] (4) The casting solution further includes 75 to 82 parts of organic solvent;

[0029] (5) The pore-forming agent includes one or more of polyvinylpyrrolidone, polyethylene glycol, polypropylene glycol, aminopropyltriethoxysilane, and acrylic acid;

[0030] (6) The casting solution includes 0.5 to 2 parts of a crosslinking agent;

[0031] (7) The inorganic nanomaterials include one or two of zirconium oxide and magnesium oxide.

[0032] In one embodiment, one or more of the following conditions are met:

[0033] (1) After preparing the composite membrane and before placing the composite membrane in the crosslinking solution, the method further includes the step of washing the composite membrane in water;

[0034] (2) The thickness of the support layer is 350μm~450μm;

[0035] (3) The pore size of the support layer is 0.1μm~0.5μm;

[0036] (4) The material of the support layer includes one or both of polyphenylene sulfide and polyether ether ketone.

[0037] This application also provides a diaphragm prepared according to the above-described preparation method.

[0038] In one embodiment, one or more of the following performance characteristics are satisfied:

[0039] (1) The soaking time is 5s~42s;

[0040] (2) Thickness is 460μm~530μm;

[0041] (3) The surface resistivity is 0.09 Ω·cm 2 ~0.14Ω·cm 2 ;

[0042] (4) The thermal stability temperature is 110℃~133℃;

[0043] (5) Fracture strength greater than 30 N / mm 2 .

[0044] Furthermore, this application provides a water electrolysis device, including an electrolytic cell, the electrolytic cell including an anode, a cathode and a diaphragm placed in an electrolyte, the diaphragm being placed between the anode and the cathode, the diaphragm including a diaphragm prepared by the preparation method described above or a diaphragm as described above.

[0045] In one embodiment, the electrolyte is an alkaline electrolyte.

[0046] This application also provides the application of the membrane prepared by the above-described method, or the membrane as described above, in the electrolysis of water to produce hydrogen.

[0047] The membrane provided in this application optimizes the preparation process. The post-treatment of immersing the membrane in a cross-linking agent solution after the composite membrane preparation is completed can optimize the interfacial compatibility between the layers of the composite membrane and improve the high-temperature stability of the membrane. Detailed Implementation

[0048] This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application. Of course, they are merely examples and are not intended to limit this application. Furthermore, reference numerals and / or letters may be repeated in different instances. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or settings discussed.

[0049] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0050] Unless otherwise specified, all percentages, fractions, and ratios are calculated based on the total mass of the compositions of this application. Unless otherwise specified, all masses of the listed ingredients are given as the content of the active substance and therefore do not include solvents or byproducts that may be present in commercially available materials. The term "percentage by mass" may be expressed by the symbol "%".

[0051] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0052] Unless otherwise stated, a singular term may include a plural term and should not be understood as having a quantity of one.

[0053] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means additional steps and components that may be added without affecting the final result. The term “comprising” also includes the terms “composed of” and “substantially composed of.” The compositions and methods / processes of this application comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0054] The terms "preferred," "more preferably," etc., used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application.

[0055] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0056] This application provides a method for preparing a diaphragm, comprising the following steps S1 to S3:

[0057] Step S1: Form a liquid film of casting solution on one or both surfaces of the support layer;

[0058] Step S2: Perform a phase transformation treatment on the support layer with the liquid film formed, solidify the liquid film, and prepare a composite film.

[0059] Step S3: Place the composite membrane in a cross-linking solution for cross-linking treatment to prepare the separator;

[0060] The cross-linking solution includes a cross-linking agent, which includes one or more of vinyltriethoxysilane, glutaraldehyde, triglycidyl isocyanurate, and polyvinyl alcohol.

[0061] The membrane provided in this application optimizes the preparation process. The post-treatment of immersing the membrane in a cross-linking agent solution after the composite membrane preparation is completed can optimize the interfacial compatibility between the layers of the composite membrane and improve the high-temperature stability of the membrane.

[0062] In a specific example, the mass percentage of the co-crosslinking agent in the co-crosslinking solution is 1% to 3%. Specifically, the mass percentage of the co-crosslinking agent in the co-crosslinking solution can be, but is not limited to, 1%, 1.5%, 2%, 2.5%, or 3%.

[0063] In a specific example, the crosslinking aid treatment time is 1 min to 5 min. Specifically, the crosslinking aid treatment time can be, but is not limited to, 1 min, 2 min, 3 min, 4 min, or 5 min.

[0064] In one specific example, the crosslinking treatment temperature is 40°C to 50°C. Specifically, the crosslinking treatment temperature can be, but is not limited to, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, or 50°C. In one specific example, the casting solution comprises 14 to 20 parts by weight of polymer, 2 to 3 parts by weight of pore-forming agent, and 46.6 to 64 parts by weight of inorganic nanomaterials.

[0065] In a specific example, the polymer includes one or more of polysulfone, polyethersulfone, polyphenylene sulfone, polyphenylene sulfone, and polyetheretherketone. Specifically, the degree of sulfonation in the polysulfone is 0% to 10%. Understandably, when the degree of sulfonation in the polysulfone is 0%, it is sulfonated polysulfone. The degree of sulfonation in sulfonated polysulfone may be, but is not limited to, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0066] In one specific example, the weight-average molecular weight of the polymer is 56,000 to 75,000. The weight-average molecular weight of the polymer may be, but is not limited to, 56,000, 57,000, 58,000, 59,000, 60,000, 61,000, 62,000, 63,000, 64,000, 65,000, 66,000, 67,000, 68,000, 69,000, 70,000, 71,000, 72,000, 73,000, 74,000, or 75,000.

[0067] In a specific example, the inorganic nanomaterial includes one or both of zirconium oxide and magnesium oxide.

[0068] In a specific example, the particle size of the inorganic nanomaterial is 40 nm to 100 nm. The particle size of the inorganic nanomaterial can be, but is not limited to, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0069] In a specific example, the thickness of the casting solution film is 200 μm to 300 μm. The thickness of the casting solution film can be, but is not limited to, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm, 70 μm, 280 μm, 290 μm or 300 μm.

[0070] In one specific example, the casting solution also includes 75 to 82 parts of an organic solvent. Specifically, the organic solvent includes one or more of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and triethyl phosphate (TEP).

[0071] In one specific example, the porogen includes one or more of polyvinylpyrrolidone, polyethylene glycol, polypropylene glycol, aminopropyltriethoxysilane, and acrylic acid.

[0072] In one specific example, the casting solution further includes 0.5 to 2 parts of a crosslinking agent. Specifically, the crosslinking agent includes one or more of vinyltriethoxysilane, glutaraldehyde, triglycidyl isocyanate, and polyvinyl alcohol.

[0073] In step S1, the method for preparing the casting solution includes mixing a polymer, a crosslinking agent, and a pore-forming agent, heating the mixture to 60°C~100°C, and then adding inorganic nanomaterials. Understandably, the heating temperature can be, but is not limited to, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C.

[0074] Understandably, the phase transformation process in step S2 includes both gas-phase induced phase transformation and liquid-phase induced phase transformation. Specifically, gas-phase induced phase transformation is performed first, followed by liquid-phase induced phase transformation.

[0075] In a specific example, the temperature for gas-induced phase transition is 25°C to 60°C. Specifically, the temperature for gas-induced phase transition can be, but is not limited to, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, or 60°C.

[0076] In a specific example, the time for gas-phase induced phase transition is 10 s to 30 s. Specifically, the time for gas-phase induced phase transition can be, but is not limited to, 10 s, 11 s, 12 s, 13 s, 14 s, 15 s, 16 s, 17 s, 18 s, 19 s, 20 s, 21 s, 22 s, 23 s, 24 s, 25 s, 26 s, 27 s, 28 s, 29 s, or 30 s.

[0077] Furthermore, the solidified liquid undergoes a liquid-induced phase transformation, the solidified liquid comprising one or more of isopropanol, water, and N-methylpyrrolidone.

[0078] In a specific example, the temperature for liquid-induced phase transition is 25°C to 30°C. Specifically, the temperature for liquid-induced phase transition can be, but is not limited to, 25°C, 26°C, 27°C, 28°C, 29°C, or 30°C.

[0079] In a specific example, the liquid-induced phase transition time is 10 min to 15 min. Specifically, the liquid-induced phase transition time can be, but is not limited to, 10 min, 11 min, 12 min, 13 min, 14 min, or 15 min.

[0080] Specifically, a support layer with a liquid film is placed in air for gas-phase induced phase transformation, then placed in a condensing liquid for liquid-phase induced phase transformation, and the liquid film is solidified to prepare a composite membrane. Understandably, the composite membrane includes a support layer, a network cross-linked polymer membrane on one or both surfaces of the support layer, and inorganic nanomaterials dispersed within the network cross-linked polymer membrane. The pore size of the network cross-linked polymer is 0.1 μm to 2.5 μm. Specifically, the pore size of the network cross-linked polymer can be, but is not limited to, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, or 2.5 μm.

[0081] Inorganic nanomaterials can be, but are not limited to, connected to network cross-linked polymers via hydrogen bonds.

[0082] In a specific example, the thickness of the support layer is 350 μm to 450 μm. Specifically, the thickness of the support mesh can be, but is not limited to, 350 μm, 400 μm, 410 μm, 420 μm, 430 μm, 440 μm or 450 μm.

[0083] In a specific example, the pore size of the support layer is 0.1 μm to 0.5 μm. Further, the support layer has a porous structure with a mesh size of 40 to 120 mesh. Specifically, the mesh size can be, but is not limited to, 40, 50, 60, 70, 80, 90, 100, 110, or 120 mesh.

[0084] In one specific example, the material of the support layer includes one or both of polyphenylene sulfide and polyetheretherketone. The support layer may be, but is not limited to, a polyphenylene sulfide mesh, a polyphenylene sulfide nonwoven fabric, or a polyetheretherketone mesh.

[0085] After the composite membrane is prepared in step S2 and before the composite membrane is placed in the crosslinking solution in step S3, the process also includes rinsing the composite membrane in water. The purpose of rinsing with water here is to remove residual organic solvents and excess nanoparticles.

[0086] This application also provides a diaphragm prepared according to the above-described preparation method.

[0087] In a specific example, the diaphragm wetting time is 5s to 42s. Specifically, the diaphragm wetting time can be, but is not limited to, 5s, 8s, 11s, 14s, 17s, 20s, 24s, 27s, 30s, 33s, 36s, 39s, or 42s.

[0088] In one specific example, the thickness of the diaphragm is 460 μm to 530 μm. The thickness of the diaphragm can be, but is not limited to, 460 μm, 470 μm, 480 μm, 490 μm, 500 μm, 510 μm, 520 μm or 530 μm.

[0089] In a specific example, the sheet resistance of the diaphragm is 0.09 Ω·cm. 2 ~0.14Ω·cm 2 The sheet resistivity of the diaphragm can be, but is not limited to, 0.09 Ω·cm. 2 0.1Ω·cm 2 0.11Ω·cm 2 0.12Ω·cm 2 0.13Ω·cm 2 or 0.14Ω·cm 2 .

[0090] In a specific example, the thermal stability temperature of the diaphragm is 110℃~133℃. The thermal stability temperature of the diaphragm may be, but is not limited to, 110℃, 111℃, 112℃, 113℃, 114℃, 115℃, 116℃, 117℃, 118℃, 119℃, 120℃, 121℃, 122℃, 123℃, 124℃, 125℃, 126℃, 127℃, 128℃, 129℃, 130℃, 131℃, 132℃, or 133℃.

[0091] In one specific example, the diaphragm's tensile strength is greater than 30 N / mm. 2 .

[0092] Furthermore, this application provides a water electrolysis device, including an electrolytic cell, the electrolytic cell including an anode, a cathode and a diaphragm placed in an electrolyte, the diaphragm being placed between the anode and the cathode, and the diaphragm including a diaphragm prepared by the preparation method described above or a diaphragm as described above.

[0093] In one specific example, the electrolyte is an alkaline electrolyte. It is understood that the alkaline electrolyte may be, but is not limited to, an aqueous solution of potassium hydroxide.

[0094] The diaphragm of this application will be further described in detail below with reference to specific embodiments. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0095] Example 1

[0096] Prepare a diaphragm for alkaline water electrolysis to produce hydrogen using the following method:

[0097] 16g of polysulfone material (weight average molecular weight 68000), 2g of polyvinylpyrrolidone, 0.5g of triglycidyl isocyanate and 81.5g of N-methylpyrrolidone were mixed and initially heated and stirred at 60°C to form a solvent. Then 64g of nano-zirconia (particle size 50nm) was added and the mixture was stirred and dispersed for another 6 hours. After complete dissolution, the mixture was degassed before use.

[0098] After degassing, the casting solution was coated onto a 400μm thick polyphenylene sulfide mesh (50 mesh) with a thickness of 250μm, ensuring it fully saturated the support mesh. The membrane was then left to stand in 40℃ hot air for 20 seconds to induce a gas-phase inversion. Next, it was placed in a 25℃ coagulation bath (composed of pure water and isopropanol in a 9:1 mass ratio) for an immersion-precipitation phase inversion. After 10 minutes, the cured composite membrane was removed and rinsed three times with pure water to remove residual solvent. Finally, it was rinsed for 3 minutes with pure water containing a crosslinking agent (40℃, 2wt% polyvinyl alcohol). The membrane was then stored for later use.

[0099] Example 2

[0100] Prepare a diaphragm for alkaline water electrolysis to produce hydrogen using the following method:

[0101] (1) Preparation of casting solution

[0102] 16g of sulfonated polysulfone material (weight average molecular weight 68,000, sulfonation degree 10%), 2g of polyvinylpyrrolidone, 1g of triglycidyl isocyanurate and 81g of N-methylpyrrolidone were mixed and initially heated and stirred at 60°C to form a solvent. Then 64g of nano-zirconia (particle size 80nm) was added and the mixture was stirred and dispersed for another 6 hours. After complete dissolution, the mixture was degassed before subsequent use.

[0103] (2) Preparation of diaphragm

[0104] After degassing, the casting solution was coated with a 220μm thick layer of polyphenylene sulfide mesh (100 mesh) to fully saturate the support mesh. The membrane was then left to stand in air at 25°C for 30 seconds to induce a gas-phase inversion. Next, it was placed in a 25°C coagulation bath (composed of pure water and isopropanol in a 9:1 mass ratio) for an immersion-precipitation phase inversion. After 15 minutes, the cured composite membrane was removed and washed three times with pure water to remove residual solvent. Finally, it was washed for 3 minutes with pure water containing a crosslinking agent (40°C, 1.5wt% polyvinyl alcohol). The membrane was then stored for later use.

[0105] Example 3

[0106] Prepare a diaphragm for alkaline water electrolysis to produce hydrogen using the following method:

[0107] (1) Preparation of casting solution

[0108] Mix 14g of polysulfone material (weight average molecular weight 75000), 3g of polyvinylpyrrolidone, 2g of triglycidyl isocyanurate, and 81g of N-methylpyrrolidone. Initially heat and stir the solvent at 80°C, then add 64g of nano-zirconia (particle size 40nm), and continue stirring to disperse and dissolve for 6 hours. After complete dissolution, perform degassing treatment for subsequent use.

[0109] (2) Preparation of diaphragm

[0110] After degassing, the casting solution was coated onto a 350μm thick polyphenylene sulfide mesh (100 mesh) with a thickness of 220μm, ensuring it fully wetted the support mesh. The membrane was then left to stand in air at 60℃ for 30 seconds to induce a gas-phase inversion. Next, it was placed in a 25℃ coagulation bath to induce a submerged precipitation phase inversion (the coagulation bath consisted of pure water and isopropanol in a mass ratio of 8:2). After 15 minutes, the cured composite membrane was removed and washed three times with pure water to remove residual solvent. Finally, it was washed for 3 minutes with pure water containing a crosslinking agent (50℃, 3% triglycidyl isocyanate). The membrane was then stored for later use.

[0111] Example 4

[0112] Prepare a diaphragm for alkaline water electrolysis to produce hydrogen using the following method:

[0113] (1) Preparation of casting solution

[0114] Mix 20g of polysulfone material (weight average molecular weight 56000), 3g of polyvinylpyrrolidone, 2g of triglycidyl isocyanurate, and 75g of N,N-dimethylformamide. Initially heat and stir the solvent at 80°C. Then add 46.6g of nano-zirconia (particle size 100nm) and continue stirring to disperse and dissolve for 6 hours. After complete dissolution, degas the solution for subsequent use.

[0115] (2) Preparation of diaphragm

[0116] After degassing, the casting solution was coated onto a 440μm thick polyphenylene sulfide mesh with a 200μm thick casting solution (50 mesh), ensuring it fully wetted the support mesh. The membrane was then left to stand in air at 30℃ for 20 seconds to induce a gas-phase inversion. It was then placed in a 30℃ coagulation bath (pure water) to induce an immersion-precipitation phase inversion. After 15 minutes, the cured composite membrane was removed and washed three times with pure water to remove residual solvent. Finally, it was washed for 3 minutes with pure water containing a crosslinking agent (50℃, 1wt% triglycidyl isocyanate). The membrane was then stored for later use.

[0117] Example 5

[0118] Prepare a diaphragm for alkaline water electrolysis to produce hydrogen using the following method:

[0119] (1) Preparation of casting solution

[0120] Mix 16g of polyphenylene sulfone (weight average molecular weight 66000), 3g of polyethylene glycol, 2g of vinyltriethoxysilane, and 80g of N,N-dimethylacetamide. Initially heat and stir the solvent at 80°C. Then add 64g of nano-zirconia (particle size 80nm) and continue stirring to disperse and dissolve for 6 hours. After complete dissolution, degas the solution for subsequent use.

[0121] (2) Preparation of diaphragm

[0122] After degassing, the casting solution was coated onto a 450μm thick polyphenylene sulfide mesh with a 200μm thick casting solution (50 mesh), allowing it to fully saturate the support mesh. It was then left to stand in air at 40℃ for 20s to induce a gas-phase inversion. Next, it was placed in a 30℃ coagulation bath (pure water) to induce an immersion precipitation phase inversion. After 15 minutes, the cured composite membrane was removed and washed three times with pure water to remove residual solvent. Finally, it was washed for 3 minutes with pure water containing a crosslinking agent (50℃, 1wt% triglycidyl isocyanate). The membrane was then stored for later use.

[0123] Example 6

[0124] Prepare a diaphragm for alkaline water electrolysis to produce hydrogen using the following method:

[0125] (1) Preparation of casting solution

[0126] Mix 16g of polyethersulfone material (weight average molecular weight 66000), 3g of polyethylene glycol, 2g of triglycidyl isocyanate, and 80g of N-methylpyrrolidone. Initially heat and stir the solvent at 80°C, then add 64g of nano-zirconia (particle size 50nm), and continue stirring to disperse and dissolve for 6 hours. After complete dissolution, perform degassing treatment for subsequent use.

[0127] (2) Preparation of diaphragm

[0128] After degassing, the casting solution was coated onto a 400μm thick polyphenylene sulfide mesh with a 300μm casting solution (50 mesh), ensuring it fully wetted the support mesh. The membrane was then left to stand in air at 30℃ for 10 seconds to induce a gas-phase inversion. Next, it was placed in a 30℃ coagulation bath (pure water) to induce an immersion-precipitation phase inversion. After 15 minutes, the cured composite membrane was removed and washed three times with pure water to remove residual solvent. Finally, it was washed for 3 minutes with pure water containing a crosslinking agent (50℃ water temperature, 1wt% glutaraldehyde). The membrane was then stored for later use.

[0129] Example 7

[0130] Prepare a diaphragm for alkaline water electrolysis to produce hydrogen using the following method:

[0131] (1) Preparation of casting solution

[0132] Mix 16g of polysulfone material (weight average molecular weight 68000), 2g of polyvinylpyrrolidone, and 82g of N-methylpyrrolidone. Initially heat and stir the solvent at 60°C, then add 64g of nano-zirconia (particle size 50nm), and continue stirring to disperse and dissolve for 6 hours. After complete dissolution, perform degassing treatment for subsequent use.

[0133] (2) Preparation of diaphragm

[0134] After degassing, the casting solution was coated onto a 400μm thick polyphenylene sulfide mesh with a 300μm casting solution (50 mesh) to fully saturate the support mesh. It was then left to stand in air at 40℃ for 20s to induce a gas-phase inversion. Next, it was placed in a 25℃ coagulation bath to induce a submerged precipitation phase inversion (the coagulation bath consisted of pure water and isopropanol in a mass ratio of 9:1). After 10 minutes, the cured composite membrane was removed and washed three times with pure water to remove residual solvent. Finally, it was washed for 3 minutes with pure water containing a crosslinking agent (40℃ water temperature, 2wt% polyvinyl alcohol content). The membrane was then stored for later use.

[0135] Example 8

[0136] The difference from Example 1 is that, after the casting solution is scraped onto the support mesh during the film formation process, the exposure time in the air is reduced, and the phase transformation and subsequent processing steps are carried out directly in the coagulation bath under normal temperature air conditions.

[0137] Comparative Example 1

[0138] The difference from Example 1 is that no crosslinking agent was used in the post-treatment of the film-forming process.

[0139] The diaphragms prepared in each embodiment and comparative example were tested. Relevant testing equipment included a contact angle meter to verify wettability and contact angle, where wettability time refers to the time it takes for the pure aqueous solution to travel from the diaphragm surface to a contact angle of 0°; a micrometer to verify thickness; and a Princeton PARSTAT instrument to test the diaphragm surface resistivity. Surface resistivity refers to the resistance value per unit area of ​​the diaphragm, representing the resistance to current flow through the diaphragm; a lower surface resistivity indicates a reduced resistance to current flow through the diaphragm.

[0140] Thermal stability temperature and mechanical properties were determined by the following method. For thermal stability testing, a diaphragm of a certain size was immersed in a 30wt% KOH aqueous solution and heated at 100℃. The state of the diaphragm was observed after 48 hours to determine the thermal stability temperature. If the diaphragm was normal after heating at 120℃ for 48 hours (i.e., there was no difference in appearance, bubble point, etc.), but problems occurred when tested at 125℃, then the thermal stability temperature of this diaphragm was 120℃.

[0141] Mechanical properties: The diaphragm performance, including tensile strength and elongation at break, is tested using a universal testing machine. The force value at which cracks appear on the diaphragm surface during the test is used as the criterion for judgment. The criterion is: good (tensile strength greater than 38 N / mm²), good (tensile strength greater than 30 N / mm²), and fair (tensile strength greater than 25 N / mm²).

[0142] The relevant test results are shown in Table 1.

[0143] Table 1

[0144] project Immersion time (s) Film thickness (μm) <![CDATA[Sheet resistance (Ω·cm 2 ).]]> Thermal stability temperature (°C) Mechanical properties Example 1 13 500 0.09 130 good Example 2 5 520 0.1 120 good Example 3 18 460 0.14 110 better Example 4 22 530 0.1 116 better Example 5 33 520 0.13 133 good Example 6 28 490 0.12 130 good Example 7 35 510 0.14 110 better Example 8 42 500 0.13 120 better Comparative Example 1 33 505 0.14 105 better

[0145] As can be seen from the above embodiments and comparative examples, by optimizing the preparation process, specifically by using a co-crosslinking agent after the composite membrane is prepared (as in Example 1, compared to Comparative Example 1 without this step), the thermal stability temperature of the membrane increased from 105°C to 130°C, the mechanical properties were significantly improved, and the sheet resistivity decreased significantly from 0.14 Ω·cm. 2 Decreased to 0.09 Ω·cm 2Furthermore, as shown in Example 8, even when using a single immersion in a coagulation bath for phase transformation, the increase in thermal stability temperature is limited, and the sheet resistance and mechanical properties are not significantly improved compared to Example 1. This demonstrates that specific phase transformation steps and post-treatment can yield a membrane with low sheet resistance, high thermal stability temperature, and good mechanical properties. In addition, by optimizing other preparation parameters of the membrane, although Example 5 showed further improvements in thermal stability temperature and mechanical properties, its wettability and sheet resistance were not significantly improved. This indicates that further optimization of the casting solution composition, such as the molecular weight of the polymer, the size of the inorganic nanomaterials, and other preparation conditions to improve the stable network porous structure, can further yield a membrane with good wettability, low sheet resistance, high thermal stability temperature, and good mechanical properties. In Example 7, no crosslinking agent was added. Therefore, compared to Example 3 with the addition of a crosslinking agent, adding a crosslinking agent to the membrane helps to increase the membrane porosity and hydrophilicity. Although the membranes of Examples 3 and 7 have the same other properties such as sheet resistance, the membrane of Example 7 has a longer immersion time.

[0146] It is evident that the membranes prepared in the above embodiments have the advantages of short immersion time, low surface resistivity, and high thermal stability. This is because the membrane preparation method is optimized, involving two phase inversions and specific post-processing, and the use of polymers with appropriate molecular weights to form a polymer membrane skeleton structure with suitable structure, which facilitates the relative dispersion of inorganic nanomaterial particles on the skeleton; and the effective combination between the polymer skeleton and the hydrophilic nanomaterials is achieved.

[0147] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0148] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0149] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a diaphragm, characterized in that, Includes the following steps: A liquid film of casting solution is formed on one or both surfaces of the support layer; The support layer on which the liquid film is formed is subjected to a phase transformation treatment to solidify the liquid film and prepare a composite film. The composite membrane is placed in a cross-linking solution for cross-linking treatment to prepare the separator. The crosslinking solution includes a crosslinking agent, which includes one or more of vinyltriethoxysilane, glutaraldehyde, triglycidyl isocyanurate, and polyvinyl alcohol.

2. The method for preparing the diaphragm as described in claim 1, characterized in that, The crosslinking agent treatment satisfies one or two of the following conditions: (1) The mass percentage of the crosslinking agent in the crosslinking solution is 1% to 3%; (2) The crosslinking treatment time is 1 min to 5 min; (3) The temperature of the crosslinking treatment is 40℃~50℃.

3. The method for preparing the diaphragm as described in claim 1, characterized in that, The phase transformation process includes gas-phase induced phase transformation and liquid-phase induced phase transformation.

4. The method for preparing the diaphragm as described in claim 3, characterized in that, The conditions for the gas-phase induced phase transformation satisfy one or two of the following conditions: (1) The temperature of the gas-phase induced phase transformation is 25℃~60℃; (2) The time for the gas-induced phase transformation is 10s~30s.

5. The method for preparing the diaphragm as described in claim 3, characterized in that, The conditions for the liquid-induced phase transformation satisfy one or more of the following conditions: (1) The liquid phase-induced phase transformation is carried out in a coagulation liquid, wherein the coagulation liquid comprises one or more of isopropanol, water and N-methylpyrrolidone; (2) The temperature for the liquid-induced phase transformation is 25℃~30℃; (3) The liquid-induced phase transformation time is 10 min to 15 min.

6. The method for preparing the diaphragm according to any one of claims 1 to 5, characterized in that, The casting solution comprises 14 to 20 parts by weight of polymer, 2 to 3 parts by weight of pore-forming agent, and 46.6 to 64 parts by weight of inorganic nanomaterials.

7. The method for preparing the diaphragm as described in claim 6, characterized in that, One or more of the following conditions must be met: (1) The polymer includes one or more of polysulfone, polyethersulfone, polyphenylene sulfone, polyphenylsulfone, and polyetheretherketone; (2) The weight-average molecular weight of the polymer is 56,000 to 75,000; (3) The particle size of the inorganic nanomaterial is 40nm~100nm; (3) The thickness of the liquid film of the casting solution is 200μm to 300μm; (4) The casting solution further includes 75 to 82 parts of organic solvent; (5) The pore-forming agent includes one or more of polyvinylpyrrolidone, polyethylene glycol, polypropylene glycol, aminopropyltriethoxysilane, and acrylic acid; (6) The casting solution includes 0.5 to 2 parts of a crosslinking agent; (7) The inorganic nanomaterials include one or two of zirconium oxide and magnesium oxide.

8. The method for preparing the diaphragm according to any one of claims 1 to 5 and 7, characterized in that, One or more of the following conditions must be met: (1) After preparing the composite membrane and before placing the composite membrane in the crosslinking solution, the method further includes the step of washing the composite membrane in water; (2) The thickness of the support layer is 350μm~450μm; (3) The pore size of the support layer is 0.1μm~0.5μm; (4) The material of the support layer includes one or both of polyphenylene sulfide and polyether ether ketone.

9. A diaphragm, characterized in that, The diaphragm is prepared according to the preparation method according to any one of claims 1 to 8.

10. The diaphragm as claimed in claim 9, characterized in that, Meet one or more of the following performance requirements: (1) The soaking time is 5s~42s; (2) Thickness is 460μm~530μm; (3) The surface resistivity is 0.09 Ω·cm 2 ~0.14Ω·cm 2 ; (4) The thermal stability temperature is 110℃~133℃; (5) Fracture strength greater than 30 N / mm 2 .

11. A water electrolysis device, characterized in that, The invention includes an electrolytic cell comprising an anode, a cathode, and a diaphragm disposed in an electrolyte, the diaphragm being disposed between the anode and the cathode, and the diaphragm comprising a diaphragm prepared by the preparation method according to any one of claims 1 to 8 or a diaphragm according to claim 9 or 10.

12. The water electrolysis apparatus as described in claim 11, characterized in that, The electrolyte is an alkaline electrolyte.

13. The application of the membrane prepared by the method according to any one of claims 1 to 8 or the membrane according to claim 9 or 10 in the electrolysis of water to produce hydrogen.