High-performance low-cost alkaline electrolyzed water composite diaphragm and preparation method thereof

Abstract

The invention discloses a high-performance low-cost alkaline electrolyzed water composite diaphragm and a preparation method thereof. The high-hydrophilcity water-permeable membrane comprises a hydrophilic supporting mesh cloth substrate and an external high-hydrophilcity coating, the outer high-hydrophilic coating comprises a polymer, an inorganic hydrophilic filler, a reinforced fiber filler and a water-soluble dispersant. The polyphenylene sulfide fiber, the basalt fiber, the high-alkali-resistant glass fiber, the nylon fiber, the polypropylene fiber and other insulating materials which are insoluble in an organic solvent and have good high-temperature-resistant and alkali-resistant performance are introduced into the slurry of the composite diaphragm, and the fiber materials can play a role of reinforcing ribs and can bear a part of tensile force in the composite diaphragm; the toughness of the composite diaphragm coating is enhanced, and the tensile strength, the bending resistance and the friction resistance of the composite diaphragm can be obviously improved.

Description

Technical Field

[0001] This invention relates to the field of alkaline water hydrogen production membrane technology, specifically to a high-performance, low-cost alkaline water electrolysis composite membrane and its preparation method. Background Technology

[0002] In the context of global climate change and energy transition, governments worldwide are actively seeking ways to reduce carbon emissions and achieve sustainable energy development. Hydrogen energy, as a clean and efficient energy carrier, is considered a crucial component of the future energy system. Alkaline water electrolysis for hydrogen production boasts advantages such as mature technology, low cost, and simple equipment, making it an important means of achieving green hydrogen production. However, this technology also faces challenges, such as high energy consumption per unit of hydrogen production. Among these challenges, the diaphragm, as a key material in the alkaline electrolyzer, separates the anode and cathode to prevent short circuits and avoid gas mixing, while providing an efficient channel for hydroxide ions to transport from the cathode to the anode. Therefore, the performance of the diaphragm directly affects the efficiency and cost of the electrolyzer, and breakthroughs in its technology are of great significance for promoting the further development of alkaline water electrolysis for hydrogen production.

[0003] With continuous technological advancements, membrane materials have evolved from asbestos membranes to polyphenylene sulfide (PPS) membranes and then to composite membranes. Composite membranes possess numerous technical characteristics and advantages, such as high ion conductivity, high gas barrier properties, high hydrophilicity, high corrosion resistance, and excellent mechanical properties and dimensional stability. These characteristics enable composite membranes to significantly reduce energy consumption, improve hydrogen purity, and enhance the safety and reliability of the electrolyzer in alkaline water electrolysis for hydrogen production. Alkaline water electrolysis composite membranes are typically formed by coating one or more layers of inorganic functional coatings onto a PPS substrate. As a high-performance thermoplastic polymer, PPS possesses excellent heat resistance, mechanical strength, and corrosion resistance, making it one of the ideal materials for alkaline electrolyzer membranes. However, high performance often comes with high cost; the complex production process of PPS and the high price of raw materials result in a relatively expensive PPS substrate. Furthermore, whether PPS, being a hydrophobic material, can effectively combine with a hydrophilic inorganic functional coating also significantly affects the performance of the electrolyzer. In addition, the composite diaphragm is subjected to continuous scouring of high-temperature alkaline solution in the electrolytic cell for a long time, resulting in powder shedding, which affects the service life of the diaphragm and poses serious safety risks.

[0004] Therefore, enhancing the mechanical strength of composite diaphragm coatings and improving the adhesion between the coating and the substrate while reducing costs have become important means to solve the problems of stability and economy in the use of composite diaphragms. This invention enhances the mechanical strength of composite diaphragm coatings by introducing a fiber into the slurry, aiming to find a low-cost material that can replace the PPS substrate. This fiber material is insoluble or slightly soluble in organic solvents and resistant to high-temperature alkaline solutions. The substrate material replacing PPS is a highly hydrophilic and alkaline-resistant nylon material (full name: Polyamide, abbreviated as PA), also known as polyamide fiber, nylon, etc., which is a general term for thermoplastic resins containing repeating amide groups (-NHCO-) ​​in their molecular chains. Nylon is a highly polar polymer material, and its molecules can form a large number of hydrogen bonds, thus possessing a high melting point with a narrow melting range. This material exhibits excellent mechanical properties, hydrophilicity, lubricity, wear resistance, corrosion resistance, oil resistance, and barrier properties; it is non-toxic and odorless, and also has good processing performance. There are many varieties of nylon. Currently, the most widely used polyamides in the commercial market are nylon 66 and nylon 6, which are widely used in various industries. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a high-performance, low-cost alkaline water electrolysis composite membrane and its preparation method.

[0006] The first objective of this invention is to provide a high-performance, low-cost alkaline water electrolysis composite membrane, comprising a hydrophilic support mesh substrate and an external highly hydrophilic coating;

[0007] The external highly hydrophilic coating comprises a polymer, an inorganic hydrophilic filler, a reinforcing fiber filler, and a water-soluble dispersant.

[0008] In some embodiments of the present invention, the material of the hydrophilic support mesh substrate includes one or more of polytetrafluoroethylene, nylon 66, nylon 6 and polyetheretherketone.

[0009] In some embodiments of the present invention, the hydrophilic support mesh substrate is a fabric, a porous membrane, or a felt.

[0010] Furthermore, the hydrophilic support mesh substrate is preferably nylon 66 or nylon 6;

[0011] Furthermore, the hydrophilic support mesh substrate is preferably a nylon mesh fabric;

[0012] The nylon mesh fabric has an opening rate of 45%-65%, preferably 60-62%;

[0013] Furthermore, the thickness of the nylon mesh fabric is 100-300µm, preferably 100-200µm.

[0014] Furthermore, the nylon mesh fabric has a mesh count of 40-100 mesh, preferably 50-80 mesh;

[0015] In some embodiments of the present invention, the polymer includes one or more of polyacrylate, polysulfone, hydroxylated polysulfone, and polyethersulfone;

[0016] The polymer has a molecular weight of 5,000-100,000, preferably 20,000-60,000.

[0017] In some embodiments of the present invention, the inorganic hydrophilic filler includes one or more of titanium dioxide, silicon dioxide, cerium dioxide, zirconium dioxide, and hydrotalcite;

[0018] The inorganic hydrophilic filler has a particle size of 10-200 nm, preferably 20-50 nm.

[0019] In some embodiments of the present invention, the reinforcing fiber filler includes one or more of basalt fiber, polypropylene fiber, high alkali resistant glass fiber, polyphenylene sulfide fiber and nylon fiber;

[0020] The diameter of the reinforcing fiber filler is 5-20µm, preferably 7-15µm, and the fiber length is 100-500µm, preferably 0.15-1mm.

[0021] In some embodiments of the present invention, the water-soluble dispersant is a modified polyurethane dispersant (BASF Efka PU4063 AN dispersant).

[0022] The second objective of this invention is to provide a method for preparing the high-performance, low-cost alkaline water electrolysis composite membrane, comprising the following steps:

[0023] The polymer is added to an organic solvent and stirred to dissolve, resulting in a polymer solution.

[0024] A water-soluble dispersant, an inorganic hydrophilic filler, and a reinforcing fiber filler are added to the polymer solution and mixed and dispersed to obtain a highly hydrophilic coating slurry.

[0025] The highly hydrophilic coating slurry is coated onto the surface of a hydrophilic support mesh substrate, and then immersed in a water bath for phase transformation to obtain the high-performance, low-cost alkaline water electrolysis composite membrane.

[0026] In some embodiments of the present invention, the water-soluble dispersant includes a modified polyurethane dispersant (BASF Efka PU4063 AN dispersant).

[0027] The organic solvent includes one or more of N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO);

[0028] The polymer is selected from one or more of polyacrylate, polysulfone, hydroxylated polysulfone, and polyethersulfone;

[0029] The polymer has a molecular weight of 5,000-100,000, preferably 20,000-60,000.

[0030] The materials for the hydrophilic support mesh substrate include one or more of polytetrafluoroethylene, nylon 66, nylon 6, and polyetheretherketone.

[0031] In some embodiments of the present invention, the solid content of the polymer solution is 10-30%, preferably 15-20%;

[0032] The inorganic hydrophilic filler accounts for 20-50% of the total mass of the highly hydrophilic coating slurry, preferably 25-40%;

[0033] The amount of reinforcing fiber filler added is 1wt%-10wt% of the total amount of polymer and inorganic hydrophilic filler, preferably 1%-6%. If the amount of reinforcing fiber added is too small, the reinforcing effect will be poor, and if the amount added is too large, the surface resistance of the composite membrane will be increased.

[0034] The amount of water-soluble dispersant added is 0.5wt%-4wt% of the total amount of inorganic hydrophilic filler and reinforcing fiber filler.

[0035] The beneficial effects of this invention are:

[0036] To enhance the coating strength of composite diaphragms, this invention introduces insulating materials such as polyphenylene sulfide fibers, basalt fibers, high alkali-resistant glass fibers, nylon fibers, and polypropylene fibers into the slurry of the composite diaphragm. These materials are insoluble in organic solvents and have good resistance to high-temperature alkaline solutions. These fiber materials can act as "reinforcing ribs," bearing part of the tensile force in the composite diaphragm and enhancing the toughness of the composite diaphragm coating. This significantly improves the tensile strength, bending resistance, and abrasion resistance of the composite membrane.

[0037] This invention introduces a modified polyurethane dispersant into the slurry formulation. The modified polyurethane molecular chain contains primary / secondary amine (-NH2 / -NHR) and carboxyl (-COOH) groups, while the inorganic hydrophilic filler has abundant hydroxyl (-OH) groups. The groups of both groups are bonded together either through coordinate bonds or by forming strong hydrogen bonds, causing the dispersant molecular chain to be tightly bound to the surface of the inorganic hydrophilic filler particles, preventing particle agglomeration, thereby making the polymer slurry more stable and less prone to sedimentation. On the other hand, it can also appropriately reduce the viscosity of the slurry, making it suitable for coating processes.

[0038] This invention uses a nylon mesh fabric to replace the PPS mesh fabric. Nylon is a naturally hydrophilic material. Compared to the less hydrophilic PPS mesh fabric, using a more hydrophilic substrate to prepare the diaphragm enhances the bonding force between the adhesive and the substrate mesh fabric, thereby increasing the diaphragm strength. Furthermore, the price of nylon mesh fabric is 10 times lower than that of expensive PPS mesh fabric. In traditional composite diaphragm raw materials, PPS mesh fabric accounts for almost 60% of the total raw material cost. Therefore, using nylon mesh fabric as the supporting substrate mesh fabric can reduce the raw material cost of composite diaphragms by approximately 50%. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the present invention. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0041] Example 1:

[0042] This embodiment provides a high-performance, low-cost alkaline water electrolysis composite membrane and its preparation method, as detailed below:

[0043] I. Raw material information: Nylon 66 woven mesh (50 mesh, 150µm filament diameter, 50% open area) is used as the base. The hydrophilic coating slurry is 17wt% (solid content of polymer solution). The mass ratio of PSU to ZrO2 is 1:3 (accounting for 33% of the total slurry mass). The amount of dispersant added accounts for 2wt% of the mass of ZrO2. The amount of basalt fiber added accounts for 3wt% of the sum of the masses of PSU and ZrO2.

[0044] II. Preparation method:

[0045] 1. Preparation of hydrophilic coating slurry: Weigh 20.5g of polysulfone (molecular weight 20000-60000) and add it to NMP, and stir at 700 rpm for 4 h until the polysulfone is completely dissolved to obtain a polymer solution (the solid content of the polymer solution is 17wt%). Weigh 1.23g of modified polyurethane dispersant (BASF Efka PU4063 AN dispersant) and add it to the polymer solution, and stir at 400 rpm for 2 h to obtain a polymer solution containing the dispersant. Weigh 61.5g of ZrO2 hydrophilic filler particles (particle size 50nm) and 2.46g of basalt fiber (fiber diameter 8µm, fiber length 0.5mm), and slowly add ZrO2 to the polymer solution containing the dispersant in three batches to ensure that the powder does not splash out. Then add the basalt fiber to the polymer solution, and continue stirring at 1400 rpm for 4 h. After degassing, the hydrophilic coating slurry is obtained and ready for use.

[0046] 2. Composite membrane coating: The hydrophilic coating slurry obtained in step 1 is coated on both sides of a nylon 6 (50 mesh, 150µm filament diameter) mesh with a thickness of 280μm using a 600μm slit doctor blade to obtain the composite material.

[0047] 3. Phase transformation curing: The above composite material is immersed in a 25°C water bath for 5 minutes to obtain a composite membrane with a thickness of 450 μm through the phase transformation process.

[0048] Example 2:

[0049] This embodiment provides a high-performance, low-cost alkaline water electrolysis composite membrane and its preparation method, as detailed below:

[0050] I. Raw material information: Nylon 66 (50 mesh, 150µm filament diameter, 50% open porosity) is used as the base material. The hydrophilic coating slurry is 17wt% (solid content of polymer solution). PSU: ZrO2 = 1:3 (accounting for 33% of the total slurry mass). The amount of dispersant added accounts for 3wt% of the ZrO2 mass. The amount of basalt fiber added accounts for 3% of the sum of the mass of PSU and ZrO2.

[0051] II. Preparation method:

[0052] 1. Preparation of hydrophilic coating slurry: Weigh 20.5g of polysulfone (molecular weight 20000-60000) and add it to NMP solution, and stir at 700 rpm for 4 h until the polysulfone is completely dissolved to obtain a polymer solution; weigh 1.85g of modified polyurethane dispersant (BASF Efka PU4063 AN dispersant) and add it to the polymer solution, and stir at 400 rpm for 2 h to obtain a polymer solution containing the dispersant; weigh 61.5g of ZrO2 hydrophilic filler particles (particle size 50nm) and 2.46g of basalt fiber (fiber diameter 8µm, fiber length 0.5mm), add ZrO2 slowly in three batches to the polymer solution containing the dispersant to ensure that the powder does not splash out, then add the basalt fiber to the polymer solution, and continue stirring at 1400 rpm for 4 h. After degassing, the hydrophilic coating slurry is obtained for later use.

[0053] 2. Composite membrane coating: The hydrophilic coating slurry obtained in step 1 is coated on both sides of a nylon 6 (50 mesh, 150µm filament diameter) mesh with a thickness of 280μm using a 600μm slit doctor blade to obtain the composite material.

[0054] 3. Phase transformation curing: The above composite material is immersed in a 25°C water bath for 5 minutes to obtain a composite membrane with a thickness of 450 μm through the phase transformation process.

[0055] Example 3:

[0056] This embodiment provides a high-performance, low-cost alkaline water electrolysis composite membrane and its preparation method, as detailed below:

[0057] I. Raw material information: Nylon 66 woven mesh (50 mesh, 150µm filament diameter, 50% open area) is used as the base. The hydrophilic coating slurry is 17wt% (polymer solution solid content), PSU: ZrO2 = 1:3 (accounting for 33% of the total slurry mass), the amount of dispersant added accounts for 4wt% of the ZrO2 mass, and the amount of basalt fiber added accounts for 3% of the sum of the mass of PSU and ZrO2.

[0058] II. Preparation method:

[0059] 1. Preparation of hydrophilic coating slurry: Weigh 20.5g of polysulfone (molecular weight 20000-60000) and add it to NMP solution, and stir at 700 rpm for 4 h until the polysulfone is completely dissolved to obtain a polymer solution; weigh 2.46g of modified polyurethane dispersant (BASF Efka PU4063 AN dispersant) and add it to the polymer solution, and stir at 400 rpm for 2 h to obtain a polymer solution containing the dispersant; weigh 61.5g of ZrO2 hydrophilic filler particles (particle size 50nm) and 2.46g of basalt fiber (fiber diameter 8µm, fiber length 0.5mm), add ZrO2 slowly in three batches to the polymer solution containing the dispersant, then add the basalt fiber, and continue stirring at 1400 rpm for 4 h. After degassing, the hydrophilic coating slurry is obtained and ready for use.

[0060] 2. Composite membrane coating: The hydrophilic coating slurry obtained in step 1 is coated on both sides of a nylon 6 (50 mesh, 150µm filament diameter) mesh with a thickness of 280μm using a 600μm slit doctor blade to obtain the composite material.

[0061] 3. Phase transformation curing: The above composite material is immersed in a 25°C water bath for 5 minutes to obtain a composite membrane with a thickness of 450 μm through the phase transformation process.

[0062] Example 4:

[0063] This embodiment provides a high-performance, low-cost alkaline water electrolysis composite membrane and its preparation method, as detailed below:

[0064] I. Raw Material Information: Nylon 66 (50 mesh, 150µm filament diameter, 50% open porosity) was used as the base material. The coating slurry was 17wt% (polymer solution solid content), PSU: ZrO2 = 1:3 (accounting for 33% of the total slurry mass), the dispersant amount was 2wt% of the ZrO2 mass, and the basalt fiber amount was 2% of the sum of the PSU and ZrO2 masses.

[0065] II. Preparation method:

[0066] 1. Preparation of hydrophilic coating slurry: Weigh 20.5g of polysulfone (molecular weight 20000-60000) and add it to NMP solution, and stir at 700 rpm for 4 h until the polysulfone is completely dissolved to obtain a polymer solution; weigh 1.23g of modified polyurethane dispersant (BASF Efka PU4063 AN dispersant) and add it to the polymer solution, and stir at 400 rpm for 2 h to obtain a polymer solution containing the dispersant; weigh 61.5g of ZrO2 hydrophilic filler particles (particle size 50nm) and 1.64g of basalt fiber (fiber diameter 8µm, fiber length 0.5mm), add ZrO2 in three batches to the polymer solution containing the dispersant, then add the basalt fiber, and continue stirring at 1400 rpm for 4 h. After degassing, the hydrophilic coating slurry is obtained for later use.

[0067] 2. Composite membrane coating: The hydrophilic coating slurry obtained in step 1 is coated on both sides of a nylon 6 (50 mesh, 150µm filament diameter) mesh with a thickness of 280μm using a 600μm slit doctor blade to obtain the composite material.

[0068] 3. Phase transformation curing: The above composite material is immersed in a 25°C water bath for 5 minutes to obtain a composite membrane with a thickness of 450 μm through the phase transformation process.

[0069] Example 5:

[0070] This embodiment provides a high-performance, low-cost alkaline water electrolysis composite membrane and its preparation method, as detailed below:

[0071] I. Raw material information: Nylon 66 (50 mesh, 150µm filament diameter, 50% open porosity) is used as the base, the hydrophilic coating slurry is 17wt% (solid content of polymer solution), PSU: ZrO2=1:3 (accounting for 33% of the total slurry mass), the amount of dispersant added accounts for 2wt% of the ZrO2 mass, and the amount of basalt fiber added accounts for 4% of the sum of the mass of PSU and ZrO2.

[0072] II. Preparation method:

[0073] 1. Preparation of hydrophilic coating slurry: Weigh 20.5g of polysulfone (molecular weight 20000-60000) and add it to NMP solution, and stir at 700 rpm for 4 h until the polysulfone is completely dissolved to obtain a polymer solution; weigh 1.23g of modified polyurethane dispersant (BASF Efka PU4063 AN dispersant) and add it to the polymer solution, and stir at 400 rpm for 2 h to obtain a polymer solution containing the dispersant; weigh 61.5g of ZrO2 hydrophilic filler particles (particle size 50nm) and 3.28g of basalt fiber (fiber diameter 8µm, fiber length 0.5mm), and slowly add ZrO2 to the polymer solution containing the dispersant in three batches to ensure that the powder does not splash out, and then add basalt fiber to the polymer solution, and continue stirring at 1400 rpm for 4 h. After degassing, the hydrophilic coating slurry is obtained for later use.

[0074] 2. Composite membrane coating: The hydrophilic coating slurry obtained in step 1 is coated on both sides of a nylon 6 (50 mesh, 150µm filament diameter) mesh with a thickness of 280μm using a 600μm slit doctor blade to obtain the composite material.

[0075] 3. Phase transformation curing: The above composite material is immersed in a 25°C water bath for 5 minutes to obtain a composite membrane with a thickness of 450 μm through the phase transformation process.

[0076] Example 6:

[0077] This embodiment provides a high-performance, low-cost alkaline water electrolysis composite membrane and its preparation method, as detailed below:

[0078] I. Raw Material Information: Nylon 66 (80 mesh, 100µm filament diameter, 45% open porosity) was used as the base material. The coating slurry was 17wt% (solid content of polymer solution), PSU: ZrO2 = 1:3 (accounting for 33% of the total slurry mass), the amount of dispersant added was 2% (accounting for the sum of the mass of ZrO2 and basalt fiber), and the amount of basalt fiber added was 3% (accounting for the sum of the mass of PSU and ZrO2).

[0079] II. Preparation method:

[0080] 1. Preparation of hydrophilic coating slurry: Same as in Example 1.

[0081] 2. Composite membrane coating: The hydrophilic coating slurry obtained in step 1 is coated on both sides of a 150μm thick nylon 66 (80 mesh, 100µm filament diameter) mesh using a 400μm slit doctor blade to obtain the composite material.

[0082] 3. Phase transformation curing: The above composite material is immersed in a 25°C water bath for 5 minutes to obtain a composite membrane with a thickness of 260 μm through the phase transformation process.

[0083] Comparative Example 1:

[0084] This comparative example provides a high-performance, low-cost alkaline water electrolysis composite membrane and its preparation method, as detailed below:

[0085] I. Raw material information: PPS (50 mesh, 150µm filament diameter, 50% open porosity) is used as the base. The coating slurry is 17wt% (solid content of polymer solution), PSU: ZrO2=1:3 (accounting for 31.6% of the total slurry mass), the amount of dispersant added is 2wt% of the total mass of ZrO2 and basalt fiber, and the amount of basalt fiber added is 3% of the total mass of PSU and ZrO2.

[0086] II. Preparation method:

[0087] 1. Preparation of hydrophilic coating slurry: Same as in Example 1.

[0088] 2. Composite membrane coating: The coating process is the same as in Example 1, except that the supporting mesh is replaced with PPS (50 mesh, 150µm wire diameter, 50% porosity).

[0089] 3. Phase transformation curing: Example 1;

[0090] Comparative Example 2:

[0091] This comparative example provides a high-performance, low-cost alkaline water electrolysis composite membrane and its preparation method, as detailed below:

[0092] I. Raw material information: PPS (50 mesh, 150µm filament diameter, 50% open porosity) is used as the base, the coating slurry is 17wt% (solid content of polymer solution), PSU: ZrO2=1:3 (accounting for 33% of the total slurry mass), the amount of dispersant added is 2% (accounting for the sum of ZrO2 and basalt fiber mass), and no basalt fiber is added.

[0093] II. Preparation method:

[0094] 1. Preparation of hydrophilic coating slurry: Weigh 20.5g of polysulfone (molecular weight 20000-60000) and add it to the dispersant solution, and stir at 700 rpm for 4 h until the polysulfone is completely dissolved to obtain a polymer solution; weigh 1.23g of modified polyurethane dispersant (BASF Efka PU4063 AN dispersant) and add it to the polymer solution, and stir at 400 rpm for 2 h to obtain a dispersant solution; weigh 61.5g of ZrO2 hydrophilic filler particles (particle size 50nm) and add them to the polymer solution in three batches, and continue stirring at 1400 rpm for 4 h. After degassing, the hydrophilic coating slurry is obtained for later use.

[0095] 2. Composite membrane coating: Same as in Example 1.

[0096] 3. Phase transformation curing: Same as in Example 1.

[0097] Comparative Example 3:

[0098] This embodiment provides a high-performance, low-cost alkaline water electrolysis composite membrane and its preparation method, as detailed below:

[0099] I. Raw material information: PPS (50 mesh, 150µm filament diameter, 50% open porosity) is used as the base, the hydrophilic coating slurry is 17wt% (polymer solution solid content), PSU: ZrO2=1:3 (accounting for 33% of the total slurry mass), no dispersant or basalt fiber is added.

[0100] II. Preparation method:

[0101] 1. Preparation of hydrophilic coating slurry: Weigh 20.5g of polysulfone (molecular weight 20000-60000) and add it to 100g of NMP. Stir at 700rpm for 4h until the polysulfone is completely dissolved. Weigh 61.5g of ZrO2 hydrophilic filler particles (particle size 50nm) and add them to the polymer solution in three batches. Continue stirring at 1400rpm for 4h. After degassing, the hydrophilic coating slurry is obtained and ready for use.

[0102] 2. Composite membrane coating: Same as in Example 1.

[0103] 3. Phase transformation curing: Same as in Example 1.

[0104] The raw material situation is summarized in Table 1:

[0105] Table 1

[0106] Test results:

[0107] 1. Tensile strength and alkali resistance tests of Nylon 66 (50 mesh, 150µm filament diameter, 50% open area) mesh and PPS (50 mesh, 150µm filament diameter, 50% open area) mesh.

[0108] Table 2

[0109] Test results show that nylon 66 and PPS mesh fabric of the same specifications have comparable tensile strength and alkali resistance. Therefore, nylon 66 can replace PPS mesh fabric as a supporting mesh fabric in alkaline electrolytic water composite membranes, thereby reducing costs.

[0110] 2. Basic performance testing

[0111] Table 3

[0112] Note: Reference standard: Test methods 7.2, 7.8, 7.17, and 7.10 in T / CI 1078-2025.

[0113] 3. Ultrasonic shedding rate test of composite diaphragm

[0114] Table 4

[0115] Note: For specific testing methods, please refer to section 7.14.2 of the group standard T / CI 1078-2025.

[0116] 4. Peel strength test results

[0117] Table 5

[0118] Note: For specific testing methods, please refer to section 7.13 of the group standard T / CI 1078—2025.

[0119] The test results above show that the amount of dispersant added significantly affects the viscosity of the composite diaphragm slurry; the more dispersant added, the lower the viscosity (compare Examples 1, 2, 3 and Comparative Example 1). The addition of dispersant has little effect on the various properties of the composite diaphragm. The addition of reinforcing fibers can significantly reduce the peeling rate of the composite coating (compare Example 1 with Comparative Examples 1 and 3) and improve the peel strength of the composite diaphragm coating (compare Example 1 with Comparative Examples 1 and 3), increasing the mechanical properties of the composite diaphragm and laying the foundation for its long service life. It also has a reverse effect on the sheet resistance (compare Example 1 with Comparative Examples 1 and 2), but the impact is small and can be controlled by adjusting the amount added to ensure that the sheet resistance is not affected. The addition of Nylon-66 significantly improves the peel strength of the composite diaphragm coating (compare Example 1 with Comparative Example 2).

[0120] In summary, the dispersant, toughening fiber, and nylon support mesh provided by this invention can significantly improve the coating strength and adhesion between the composite diaphragm and the substrate while ensuring that the surface resistance of the composite diaphragm does not increase. This enhances the abrasion resistance, pressure resistance, and resistance to various external impacts of the composite diaphragm under actual working conditions, ensuring the service life of the composite diaphragm, and greatly reducing the production cost of the composite diaphragm.

Claims

1. A high performance low cost alkaline electrolytic water composite separator, characterized by, The hydrophilic support mesh substrate and the outer high hydrophilic coating layer are provided. The outer high hydrophilic coating layer comprises a polymer, an inorganic hydrophilic filler, a reinforcing fiber filler, and a water-soluble dispersant.

2. A high performance low cost alkaline electrolysis water composite separator as claimed in claim 1, characterized by, The material of the hydrophilic support mesh substrate comprises one or more of polytetrafluoroethylene, nylon 66, nylon 6, and polyether ether ketone.

3. A high performance low cost alkaline electrolytic water composite separator as claimed in claim 1, wherein, The hydrophilic support mesh substrate is a fabric, a porous membrane, or a felt.

4. A high performance low cost alkaline electrolytic water composite separator as claimed in claim 1, wherein, The polymer comprises one or more of polyacrylate, polysulfone, hydroxylated polysulfone, and polyether sulfone. The molecular weight of the polymer is 5000-100000.

5. A high performance, low cost alkaline electrolytic water composite separator as defined in claim 1, wherein, The inorganic hydrophilic filler comprises one or more of titanium dioxide, silicon dioxide, cerium dioxide, zirconium dioxide, and hydrotalcite. The particle size of the inorganic hydrophilic filler is 10-200 nm.

6. A high performance, low cost alkaline electrolytic water composite separator as defined in claim 1, wherein, The reinforcing fiber filler comprises one or more of basalt fiber, polypropylene fiber, high-alkali-resistant glass fiber, polyphenylene sulfide fiber, and nylon fiber. The diameter of the reinforcing fiber filler is 5-20 µm.

7. A high performance low cost alkaline electrolytic water composite separator as claimed in claim 1, wherein, The water-soluble dispersant is a modified polyurethane dispersant.

8. A method of preparing a high performance low cost alkaline electrolytic water composite separator according to any one of claims 1 to 7, characterized by, The method comprises the following steps: The polymer is added to an organic solvent and stirred until completely dissolved to obtain a polymer solution. The water-soluble dispersant, the inorganic hydrophilic filler, and the reinforcing fiber filler are added to the polymer solution and mixed and dispersed to obtain a high hydrophilic coating layer slurry. The high hydrophilic coating layer slurry is coated on the surface of the hydrophilic support mesh substrate, and then immersed in a water bath for phase inversion to obtain the high-performance low-cost alkaline electrolysis water composite diaphragm.

9. The production method according to claim 8, wherein The water-soluble dispersant comprises a modified polyurethane dispersant. The organic solvent comprises one or more of N-methylpyrrolidone, N-ethylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide. The polymer is selected from one or more of polyacrylate, polysulfone, hydroxylated polysulfone, and polyether sulfone. The molecular weight of the polymer is 5000-100000. The material of the hydrophilic support mesh substrate comprises one or more of polytetrafluoroethylene, nylon 66, nylon 6, and polyether ether ketone.

10. The production method according to claim 8, wherein The solid content of the polymer solution is 10-30%. The mass ratio of the inorganic hydrophilic filler to the total high hydrophilic coating layer slurry is 20-50%. The amount of the reinforcing fiber filler added is 1wt%-10wt% of the total amount of the polymer and the inorganic hydrophilic filler. The amount of the water-soluble dispersant added is 0.5wt%-4wt% of the total amount of the inorganic hydrophilic filler and the reinforcing fiber filler.

Images