Alkaline electrolyzed water composite diaphragm with high wear resistance and stepped coating as well as preparation method and application of alkaline electrolyzed water composite diaphragm

Abstract

The invention discloses an alkaline electrolyzed water composite diaphragm with high wear resistance and a stepped coating as well as a preparation method and application of the alkaline electrolyzed water composite diaphragm. The alkaline electrolyzed water composite diaphragm comprises a substrate supporting layer and high-hydrophilic coatings arranged on the two sides of the substrate supporting layer, and further comprises high-wear-resistant coatings arranged on the surfaces of the high-hydrophilic coatings. The substrate supporting layer is supporting mesh cloth; the high-hydrophilic coating comprises an organic polymer containing active groups and a first inorganic hydrophilic filler; and the high-wear-resistance coating comprises an organic polymer with relatively strong wear resistance and a second inorganic hydrophilic filler. The coating strength of the composite diaphragm is improved from two aspects, firstly, the stepped design of the coating structure of the composite diaphragm improves the use stability of the diaphragm and ensures the comprehensive performance of the diaphragm; and secondly, a coupling agent is added into the slurry, so that crosslinking among the organic framework, the inorganic filler and the gridding cloth supporting substrate is promoted, and the high-performance composite diaphragm which is high in bonding strength, high in wear resistance and not prone to falling off of the coating is formed.

Description

Technical Field

[0001] This invention relates to the field of alkaline water electrolysis for hydrogen production technology, specifically to a highly wear-resistant, stepped-coating alkaline water electrolysis composite membrane, its preparation method, and its application. Background Technology

[0002] In the global wave of clean energy transition, alkaline water electrolysis for hydrogen production, with its high efficiency and cleanliness, has become one of the important means to achieve carbon neutrality. The history of alkaline water electrolysis for hydrogen production can be traced back to the 20th century, when industrial applications were just beginning. During this process, the membrane, as a key material, has undergone technological innovations from asbestos membranes to PPS membranes, and then to composite membranes.

[0003] Asbestos membranes, as the first generation of products, were gradually phased out due to their swelling in alkaline electrolytes and potential harm to human health. Subsequently, PPS membranes became the mainstream in the market due to their excellent heat resistance, mechanical strength, and electrical properties. However, the weak hydrophilicity of PPS membranes led to higher internal resistance in the electrolyzer, increasing the unit cost of hydrogen production. To overcome this drawback, composite membranes were developed. By coating a substrate material such as PPS with a slurry containing hydrophilic inorganic substances and polymers, its hydrophilicity is significantly improved, thereby reducing the internal resistance and power consumption of the electrolyzer.

[0004] Composite membranes exhibit significant electrochemical performance, but during long-term operation of the electrolytic cell, the continuous high-speed scouring by the electrolyte can cause inorganic powder to detach from the coating. Increasing the amount of polymer binder can improve this phenomenon, but it affects the hydrophilicity of the membrane. Summary of the Invention

[0005] To address the technical challenges of inorganic hydrophilic coatings, such as the risk of peeling, this invention provides a highly wear-resistant, stepped-coating alkaline electrolytic water composite diaphragm, its preparation method, and its applications. This invention improves the strength of the composite diaphragm coating in two ways: firstly, the stepped design of the composite diaphragm coating structure, with two layers: an inner layer of highly hydrophilic coating (increasing the proportion of inorganic hydrophilic powder in the inner coating formulation to maintain the high hydrophilicity of the composite diaphragm); and an outer strong skeleton support layer (applying a strong skeleton support layer on top of the inner highly hydrophilic coating). In the slurry formulation of this outer layer, the proportion of inorganic hydrophilic fillers is reduced, while the content of the organic polymer skeleton is correspondingly increased. Simultaneously, polyarylsulfone is used instead of ordinary polysulfone. Polyarylsulfone, as a polymer skeleton, has strong wear resistance, thus significantly reducing the phenomenon of powder and coating peeling on the composite diaphragm surface under high-speed, high-temperature alkaline liquid scouring conditions.

[0006] To increase the stability of the diaphragm and ensure its overall performance; secondly, to add a coupling agent to the slurry to promote cross-linking between the organic skeleton, inorganic filler and mesh support substrate, forming a high-performance composite diaphragm with high bonding strength, high wear resistance and coating that is not easy to peel off.

[0007] The first objective of this invention is to provide a method for preparing a highly wear-resistant, stepped-coating alkaline water electrolysis composite membrane, comprising the following steps:

[0008] A support mesh is provided, wherein the support mesh is subjected to corona treatment or low-temperature plasma treatment to obtain a support mesh containing active groups on its surface;

[0009] An organic polymer solution containing active groups is provided, which is mixed with a first inorganic hydrophilic filler to obtain a highly hydrophilic coating slurry;

[0010] A high-wear-resistant coating slurry is obtained by mixing an organic polymer solution with a second inorganic hydrophilic filler.

[0011] The highly hydrophilic coating slurry is coated on both sides of the support mesh fabric containing active groups on the surface to obtain an internal highly hydrophilic coating. After air bathing at 25-30℃ for 3-5 minutes, the highly wear-resistant coating slurry is coated on the internal highly hydrophilic coating to form a highly wear-resistant coating. The phase transformation yields the alkaline electrolytic water composite membrane.

[0012] In some embodiments of the present invention, the support mesh is selected from fabrics, porous membranes or felts made of polytetrafluoroethylene and / or polyphenylene sulfide.

[0013] The active groups include hydroxyl and / or carboxyl groups;

[0014] The parameters for the low-temperature plasma treatment are: power 150-300W for 30-60s, preferably 200-250W for 40-50s; the parameters for the corona treatment are: voltage 12-20kV, electrode gap 2-5mm, operating frequency 15-30Hz, treatment time 5-30s, preferably voltage 15-20kV, electrode gap 3-4mm, operating frequency 15-25Hz, treatment time 5-15s.

[0015] In some embodiments of the present invention, the solvent of the organic polymer solution containing the active group is selected from one or more of N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO).

[0016] In some embodiments of the present invention, the organic polymer containing active groups is selected from hydroxylated polysulfone and / or sulfonated polysulfone; the active groups include one or more of hydroxyl, sulfonic acid and carboxyl groups; the molecular weight of the organic polymer ranges from 20,000 to 120,000, preferably from 50,000 to 80,000.

[0017] The mass ratio of the organic polymer containing active groups to the first inorganic hydrophilic filler is 1:(2.5-4); more preferably, it is 1:(3-4).

[0018] The content of organic polymer in the highly hydrophilic coating slurry is 15-18 wt%; more preferably, it is 16-17%.

[0019] The highly hydrophilic coating slurry also includes a first silane crosslinking agent.

[0020] In some embodiments of the present invention, the first silane crosslinking agent is selected from one or more of epoxy silane coupling agents (such as KH-560), alkyl silane coupling agents (such as methyltrimethoxysilane, octyltriethoxysilane) and phenyl silane coupling agents;

[0021] In some embodiments of the present invention, during the preparation of the highly hydrophilic coating slurry, after the organic polymer and the first inorganic hydrophilic filler are mixed, the first silane crosslinking agent is added, and stirring is continued for 1-2 hours, with the slurry temperature at 50-80°C.

[0022] The content of the first silane crosslinking agent in the highly hydrophilic coating slurry is 0.1wt%-0.5wt%.

[0023] In some embodiments of the present invention, the first inorganic hydrophilic filler and the second inorganic hydrophilic filler are each independently selected from one or more of titanium dioxide, silicon dioxide, cerium dioxide, zirconium dioxide, and hydrotalcite; the particle size range is 20-150. The present invention can increase the hydrophilicity of the membrane by adding inorganic hydrophilic fillers, thereby reducing the surface resistivity of the membrane.

[0024] In some embodiments of the present invention, the mass ratio of the organic polymer with strong wear resistance to the second inorganic hydrophilic filler is 1:(1-2.5); more preferably, it is 1:(1.5-2).

[0025] Organic polymers with strong wear resistance include polyarylsulfone; this invention utilizes polyarylsulfone as the organic polymer backbone, which exhibits excellent wear resistance. The molecular weight of the organic polymer ranges from 20,000 to 120,000, preferably from 50,000 to 80,000.

[0026] The content of the organic polymer with strong wear resistance in the high wear-resistant coating slurry is 18-21 wt%; more preferably 19-20 wt%.

[0027] The high wear-resistant coating slurry also includes a second silane crosslinking agent.

[0028] In some embodiments of the present invention, the second silane crosslinking agent is selected from one or more of epoxy silane coupling agents (such as KH-560), alkyl silane coupling agents (such as methyltrimethoxysilane, octyltriethoxysilane) and phenyl silane coupling agents;

[0029] The content of the second silane crosslinking agent in the high wear-resistant coating is 0.1wt%-0.5wt%; more preferably, it is 0.2%-0.4%.

[0030] In some embodiments of the present invention, during the preparation of the high wear-resistant coating slurry, after the organic polymer and the second inorganic hydrophilic filler are mixed, a second silane crosslinking agent is added, and the mixture is stirred for 1-2 hours to disperse and grind. The slurry temperature is 50-80°C, and after degassing, the external high wear-resistant coating slurry is prepared.

[0031] In some embodiments of the present invention, the solvent of the organic polymer solution with strong wear resistance is one or more of N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO).

[0032] Phase transformation conditions: Immerse the composite coating in a water bath at 20-60℃ for 5-10 minutes to carry out the phase transformation.

[0033] The second objective of this invention is to provide a highly wear-resistant, stepped-coating alkaline water electrolysis composite membrane, prepared by the aforementioned method; comprising a substrate support layer and a highly hydrophilic coating disposed on both sides of the substrate support layer, and further comprising a highly wear-resistant coating disposed on the surface of the highly hydrophilic coating;

[0034] The thickness of the highly hydrophilic coating after it is applied and formed is 380-450μm, and the thickness of the highly hydrophilic coating on one side is 50-80μm.

[0035] The total thickness of the composite diaphragm after the high wear-resistant coating is applied and formed is 450-500μm, and the thickness of the high wear-resistant coating on one side is 10-50μm.

[0036] The base support layer is a support mesh fabric;

[0037] The highly hydrophilic coating comprises an organic polymer containing active groups and a first inorganic hydrophilic filler;

[0038] The high wear-resistant coating comprises an organic polymer with strong wear resistance and a second inorganic hydrophilic filler.

[0039] In some embodiments of the present invention, the highly hydrophilic coating further includes a first silane crosslinking agent, wherein the content of the first silane crosslinking agent in the highly hydrophilic coating slurry is 0.1wt%-0.5wt%;

[0040] The high wear-resistant coating slurry also includes a second silane crosslinking agent, and the content of the second silane crosslinking agent in the high wear-resistant coating is 0.1wt%-0.5wt%.

[0041] In some embodiments of the present invention, the mass ratio of the organic polymer containing active groups to the first inorganic hydrophilic filler is 1:(2.5-4); the mass ratio of the organic polymer with strong wear resistance to the second inorganic hydrophilic filler is 1:(1-2.5).

[0042] The supporting mesh is selected from fabrics, porous membranes or felts made of polytetrafluoroethylene and / or polyphenylene sulfide containing active groups.

[0043] The organic polymer containing the active group is selected from hydroxylated polysulfone and / or sulfonated polysulfone; the active group includes one or more of hydroxyl, sulfonic acid and carboxyl groups;

[0044] The first inorganic hydrophilic filler and the second inorganic hydrophilic filler are each independently selected from one or more of titanium dioxide, silicon dioxide, cerium dioxide, zirconium dioxide, and hydrotalcite;

[0045] Organic polymers with strong wear resistance include polysulfone.

[0046] In some embodiments of the present invention, the slurry coating and membrane forming are as follows: First, the inner high hydrophilic coating slurry is coated on both sides of a pretreated PPS support mesh with a thickness of 280μm through a 450-550μm slit to obtain the inner high hydrophilic coating. Then, the outer high wear-resistant coating slurry is coated on both sides of the inner composite layer surface through a 550-600μm slit. The composite material is then immersed in a water bath at 20-60℃ for 5-10 minutes. Through the phase transformation process, a high wear-resistant alkaline electrolytic water composite membrane with a stepped coating structure is obtained.

[0047] A third objective of this invention is to provide an alkaline water electrolysis device, comprising the aforementioned highly wear-resistant, stepped-coated alkaline water electrolysis composite diaphragm.

[0048] The beneficial effects of this invention are:

[0049] This invention features an inner layer designed as a highly hydrophilic coating: the proportion of inorganic hydrophilic powder is increased during the preparation of the inner coating to maintain the high hydrophilicity of the composite membrane; and an outer layer designed as a strong skeleton support layer: based on the inner highly hydrophilic coating, an additional strong skeleton support layer is applied to the outside. In the preparation of this layer's slurry, the proportion of inorganic hydrophilic fillers is reduced, and the content of organic polymer skeleton is correspondingly increased. At the same time, polyarylsulfone is used instead of ordinary polysulfone. As a polymer skeleton, polyarylsulfone has strong wear resistance, which can greatly reduce the phenomenon of powder and coating peeling on the surface of the composite membrane under high-speed, high-temperature alkaline liquid washing conditions.

[0050] This invention adds a silane coupling agent-type crosslinking agent to the slurry. This crosslinking agent acts as a "bridge" to form a crosslinked structure in the form of polysulfone-O-[crosslinking agent skeleton]-O-ZrO2, polysulfone-O-[crosslinking agent skeleton]-O-substrate support material, and substrate support material-O-[crosslinking agent skeleton]-O-ZrO2. This makes the entire composite membrane form a three-dimensional network structure integrating substrate support mesh, organic skeleton, and hydrophilic filler, thus preparing a high-performance composite membrane with low resistance and high wear resistance. To facilitate the use of crosslinking agents, this invention promotes a strong crosslinking effect between the organic framework, inorganic hydrophilic powder filler, and substrate support layers. The organic polymer material for the inner highly hydrophilic coating should preferably be hydroxylated polysulfone or sulfonated polysulfone. The mesh support substrate undergoes pretreatment processes such as corona discharge and plasma treatment. The purpose of this pretreatment is to introduce hydroxyl and carboxyl groups onto the substrate surface. These groups can react with the organic ends of the crosslinking agent to form covalent bonds or interpenetrating networks. The inorganic hydrophilic powder filler uses nanoscale particles, which absorb water molecules and carry hydroxyl groups. The inorganic ends of the crosslinking agent can first undergo hydrolysis using the water molecules carried by zirconium oxide to generate silanol. The hydroxyl groups carried by the silanol then undergo a condensation reaction with the hydroxyl groups of zirconium oxide, completing the non-polar crosslinking. During high-speed dispersion and stirring, the slurry temperature reaches 50-80℃, which further promotes the crosslinking reaction between the organic and inorganic ends. Attached Figure Description

[0051] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0052] Figure 1 This is a schematic diagram of the structure of polysulfone, polyethersulfone, and polyarylsulfone used in the embodiments of the present invention.

[0053] Figure 2 This is a schematic diagram of the structure of the alkaline electrolytic water composite membrane prepared according to an embodiment of the present invention. Detailed Implementation

[0054] 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.

[0055] Example 1:

[0056] This embodiment provides a highly wear-resistant, stepped-coating alkaline water electrolysis composite membrane and its preparation method, wherein the highly hydrophilic coating has a thickness of 60 μm, the highly wear-resistant coating has a thickness of 20 μm, and the total thickness is 450 μm, as shown below;

[0057] 1. Preparation of highly hydrophilic coating slurry: Weigh 9.5g of polyarylsulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 4h. Add 33.3g of ZrO2 powder with a particle size of 50nm and stir and disperse at 1400rpm for 4h. After degassing, the highly hydrophilic coating slurry is obtained and set aside.

[0058] 2. Preparation of high wear-resistant coating slurry: Weigh 11.7g of hydroxylated polysulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 6h. Add 23.4g of ZrO2 powder with a particle size of 50nm and stir and disperse at 1400rpm for 4h. After degassing, the high wear-resistant coating slurry is obtained and set aside.

[0059] 3. Plasma treatment of PPS support mesh: Cut 15cm*15cm support mesh (PPS, 280µm thick, 50 mesh) and perform plasma treatment for 60s at 150W. Coating is performed immediately after treatment.

[0060] 4. Slurry coating and molding: The highly hydrophilic slurry is coated on both sides of the plasma-treated PPS support mesh through a 500μm slit to obtain an inner highly hydrophilic coating. After air bath at 25℃ for 3 minutes, the highly wear-resistant coating slurry is coated on both sides of the inner highly hydrophilic coating through a 600μm slit to form a highly wear-resistant coating. The composite coating with the two layers above is immersed in a 40℃ water bath for 10 minutes. After phase inversion, the target composite membrane is obtained.

[0061] Example 2:

[0062] This embodiment provides a highly wear-resistant, stepped-coating alkaline water electrolysis composite diaphragm and its preparation method, wherein the highly hydrophilic coating has a thickness of 55 μm, the highly wear-resistant coating has a thickness of 30 μm, and the total thickness is 450 μm, as detailed below:

[0063] 1. Preparation of highly hydrophilic coating slurry: Weigh 9.5g of polyarylsulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 4h. Add 33.3g of ZrO2 powder with a particle size of 50nm and stir and disperse at 1400rpm for 4h. After degassing, the highly hydrophilic coating slurry is obtained and set aside.

[0064] 2. Preparation of high wear-resistant coating slurry: Weigh 11.7g of hydroxylated polysulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 6h. Add 23.4g of ZrO2 powder with a particle size of 50nm and stir and disperse at 1400rpm for 4h. After degassing, the high wear-resistant coating slurry is obtained and set aside.

[0065] 3. Plasma treatment of PPS support mesh: Cut 15cm*15cm support mesh (PPS, 280µm thick, 50 mesh) and perform plasma treatment for 60s at 150W. Coating is performed immediately after treatment.

[0066] 4. Slurry coating and molding: The hydrophilic slurry is coated on both sides of the plasma-treated PPS support mesh through a 450μm slit to obtain an inner high hydrophilic coating. After air bath at 25℃ for 3 minutes, the high wear-resistant coating slurry is coated on both sides of the inner high hydrophilic coating through a 600μm slit. The composite coating with the two layers above is immersed in a 40℃ water bath for 10 minutes. After phase inversion, the target composite membrane is obtained.

[0067] Example 3:

[0068] This embodiment provides a highly wear-resistant, stepped-coating alkaline water electrolysis composite membrane and its preparation method. The highly hydrophilic coating has a thickness of 60 μm, the highly wear-resistant coating has a thickness of 25 μm, and the total thickness is 450 μm. The organic content and hydrophilic coating content of the highly wear-resistant coating are varied, as shown below:

[0069] 1. Preparation of highly hydrophilic coating slurry: Weigh 9.5g of polyarylsulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 4h. Add 33.3g of ZrO2 powder with a particle size of 50nm and stir and disperse at 1400rpm for 4h. After degassing, the highly hydrophilic coating slurry is obtained and set aside.

[0070] 2. Preparation of high wear-resistant coating slurry: Weigh 11.7g of hydroxylated polysulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 6h. Add 18.8g of ZrO2 powder with a particle size of 50nm and stir and disperse at 1400rpm for 4h. After degassing, the high wear-resistant coating slurry is obtained and set aside.

[0071] 3. Plasma treatment of PPS support mesh: Cut 15cm*15cm support mesh (PPS, 280µm thick, 50 mesh) and perform plasma treatment for 60s at 150W. Coating is performed immediately after treatment.

[0072] 4. Slurry coating and molding: The hydrophilic slurry is coated on both sides of the plasma-treated PPS support mesh through a 500μm slit to obtain an inner high hydrophilic coating. After air bath at 25℃ for 3 minutes, the high wear-resistant coating slurry is coated on both sides of the inner high hydrophilic coating through a 600μm slit. The composite coating with the two layers above is immersed in a 40℃ water bath for 10 minutes. After phase inversion, the target composite membrane is obtained.

[0073] Example 4:

[0074] This embodiment provides a highly wear-resistant, stepped-coating alkaline water electrolysis composite membrane and its preparation method. The highly hydrophilic coating has a thickness of 60 μm, the highly wear-resistant coating has a thickness of 25 μm, and the total thickness is 450 μm. The organic content of the highly wear-resistant coating is varied, as shown below:

[0075] 1. Preparation of highly hydrophilic coating slurry: Weigh 9.5g of polyarylsulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 4h. Add 33.3g of ZrO2 powder with a particle size of 50nm and stir and disperse at 1400rpm for 4h. After degassing, the highly hydrophilic coating slurry is obtained and set aside.

[0076] 2. Preparation of high wear-resistant coating slurry: Weigh 12.5g of hydroxylated polysulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 6h. Add 18.8g of ZrO2 powder with a particle size of 50nm and stir and disperse at 1400rpm for 4h. After degassing, the high wear-resistant coating slurry is obtained and set aside.

[0077] 3. Plasma treatment of PPS support mesh: Cut 15cm*15cm support mesh (PPS, 280µm thick, 50 mesh) and perform plasma treatment for 60s at 150W. Coating is performed immediately after treatment.

[0078] 4. Slurry coating and molding: The hydrophilic slurry is coated on both sides of the plasma-treated PPS support mesh through a 500μm slit to obtain an inner high hydrophilic coating. After air bath at 25℃ for 3 minutes, the high wear-resistant coating slurry is coated on both sides of the inner high hydrophilic coating through a 600μm slit. The composite coating with the two layers above is immersed in a 40℃ water bath for 10 minutes. After phase inversion, the target composite membrane is obtained.

[0079] Example 5:

[0080] This embodiment provides a highly wear-resistant, stepped-coating alkaline water electrolysis composite diaphragm and its preparation method. The highly hydrophilic coating has a thickness of 60 μm, the highly wear-resistant coating has a thickness of 25 μm, and the total thickness is 450 μm. 0.2% of a silane crosslinking agent is added, as detailed below:

[0081] 1. Preparation of highly hydrophilic coating slurry: Weigh 9.5g of polyarylsulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 4h. Add 33.3g of ZrO2 powder with a particle size of 50nm. Stir and disperse at 1400rpm for 3h. Add 0.086g of epoxy silane coupling agent (KH-560). Continue to disperse and stir at 1400rpm for 1h. After degassing, the highly hydrophilic coating slurry is obtained and ready for use.

[0082] 2. Preparation of high wear-resistant coating slurry: Weigh 11.7g of hydroxylated polysulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 6h. Add 23.4g of ZrO2 powder with a particle size of 50nm. Stir and disperse at 1400rpm for 3h. Add 0.07g of epoxy silane coupling agent (KH-560). Continue to disperse and stir at 1400rpm for 1h. After degassing, the high wear-resistant coating slurry is obtained and ready for use.

[0083] 3. Plasma treatment of PPS support mesh: Cut 15cm*15cm support mesh (PPS, 280µm thick, 50 mesh) and perform plasma treatment for 60s at 150W. Coating is performed immediately after treatment.

[0084] 4. Slurry coating and molding: The hydrophilic slurry is coated on both sides of the plasma-treated PPS support mesh through a 500μm slit to obtain an inner high hydrophilic coating. After air bath at 25℃ for 3 minutes, the high wear-resistant coating slurry is coated on both sides of the inner high hydrophilic coating through a 600μm slit. The composite coating with the two layers above is immersed in a 40℃ water bath for 10 minutes. After phase inversion, the target composite membrane is obtained.

[0085] Example 6:

[0086] This embodiment provides a highly wear-resistant, stepped-coating alkaline water electrolysis composite diaphragm and its preparation method. The highly hydrophilic coating has a thickness of 60 μm, the highly wear-resistant coating has a thickness of 25 μm, and the total thickness is 450 μm. A silane crosslinking agent of 0.4 wt% is added. Details are as follows:

[0087] 1. Preparation of highly hydrophilic coating slurry: Weigh 9.5g of polyarylsulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 4h. Add 33.3g of ZrO2 powder with a particle size of 50nm. Stir and disperse at 1400rpm for 3h. Add 0.171g of epoxy silane coupling agent (KH-560). Continue to disperse and stir at 1400rpm for 1h. After degassing, the highly hydrophilic coating slurry is obtained and ready for use.

[0088] 2. Preparation of high wear-resistant coating slurry: Weigh 11.7g of hydroxylated polysulfone (molecular weight of 50,000-80,000) and add it to 50ml of NMP. Stir at 400rpm for 6h. Add 23.4g of ZrO2 powder with a particle size of 50nm. Stir and disperse at 1400rpm for 3h. Add 0.14g of epoxy silane coupling agent (KH-560). Continue to disperse and stir at 1400rpm for 1h. After degassing, the high wear-resistant coating slurry is obtained and ready for use.

[0089] 3. Plasma treatment of PPS support mesh: Cut 15cm*15cm support mesh (PPS, 280µm thick, 50 mesh) and perform plasma treatment for 60s at 150W. Coating is performed immediately after treatment.

[0090] 4. Slurry coating and molding: The hydrophilic slurry is coated on both sides of the plasma-treated PPS support mesh through a 500μm slit to obtain an inner high hydrophilic coating. After air bath at 25℃ for 3 minutes, the high wear-resistant coating slurry is coated on both sides of the inner high hydrophilic coating through a 600μm slit. The composite coating with the two layers above is immersed in a 40℃ water bath for 10 minutes. After phase inversion, the target composite membrane is obtained.

[0091] Comparative Example 1:

[0092] This comparative example provides a highly wear-resistant, stepped-coating alkaline water electrolysis composite membrane and its preparation method, which is similar to the preparation method in Example 1, except that it only has a highly hydrophilic coating and no wear-resistant coating, with a total thickness of 450 μm, as shown below:

[0093] 1. Preparation of highly hydrophilic coating slurry: Weigh 9.5g of polyarylsulfone and add it to 50ml of NMP. Stir at 400rpm for 4h. Add 33.3g of ZrO2 powder with a particle size of 50nm. Stir and disperse at 1400rpm for 4h. After degassing, the highly hydrophilic coating slurry is obtained and set aside.

[0094] 2. Plasma treatment of PPS support mesh: Cut 15cm*15cm support mesh (PPS, 280µm thick, 50 mesh) and perform plasma treatment for 60s at 150W. Coating is performed immediately after treatment.

[0095] 3. Slurry coating and molding: The hydrophilic slurry is coated on both sides of the plasma-treated PPS support mesh through a 600μm slit to obtain an internal highly hydrophilic coating. The composite coating is then immersed in a 40℃ water bath for 10 minutes, and the target composite membrane is obtained through a phase inversion process.

[0096] Comparative Example 2:

[0097] This comparative example provides a highly wear-resistant, stepped-coating alkaline water electrolysis composite membrane and its preparation method, similar to Example 1, except that it has no highly hydrophilic coating, only a highly wear-resistant coating, with a total thickness of 450 μm, as shown below:

[0098] 1. Preparation of high wear-resistant coating slurry: Weigh 11.7g of hydroxylated polysulfone and add it to 50ml of NMP. Stir at 400rpm for 6h. Add 23.4g of ZrO2 powder with a particle size of 50nm. Stir and disperse at 1400rpm for 4h. After degassing, the high wear-resistant coating slurry is obtained and set aside.

[0099] 2. Plasma treatment of PPS support mesh: Cut 15cm*15cm support mesh (PPS, 280µm thick, 50 mesh) and perform plasma treatment for 60s at 150W. Coating is performed immediately after treatment.

[0100] 3. Slurry coating and molding: The high wear-resistant coating slurry is coated on both sides of the plasma-treated PPS support mesh through a 600μm slit, and then quickly immersed in a 40℃ water bath for 10 minutes. The target composite membrane is obtained through the phase transformation process.

[0101] Comparative Example 3:

[0102] This comparative example provides a highly wear-resistant, stepped-coating alkaline water electrolysis composite diaphragm and its preparation method, which is the same as the preparation method in Example 1, except that: it has a highly hydrophilic coating, no highly wear-resistant coating, a total thickness of 450 μm, and no PPS support cloth plasma treatment, as detailed below:

[0103] 1. Preparation of highly hydrophilic coating slurry: Weigh 9.5g of polyarylsulfone and add it to 50ml of NMP. Stir at 400rpm for 4h. Add 33.3g of ZrO2 powder with a particle size of 50nm. Stir and disperse at 1400rpm for 4h. After degassing, the highly hydrophilic coating slurry is obtained and set aside.

[0104] 2. Slurry coating and molding: The hydrophilic slurry is coated on both sides of the untreated PPS support mesh through a 600μm slit to obtain an internal highly hydrophilic coating. The composite coating is immersed in a 40℃ water bath for 10 minutes and the target composite membrane is obtained through a phase inversion process.

[0105] Table 1

[0106] Performance testing

[0107] The composite membranes obtained in the examples and comparative examples were subjected to performance tests, including thickness, porosity, sheet resistance and bubble point, as well as ultrasonic shedding rate and peel strength tests. The experimental results are shown in Tables 2-4.

[0108] 1. Basic performance testing

[0109] Table 2

[0110] Note: Reference standard: Test methods 7.2, 7.8, 7.17, and 7.10 in T / CI 1078-2025.

[0111] 2. Ultrasonic shedding rate test of composite diaphragm

[0112] Table 3

[0113] Note: For specific testing methods, please refer to section 7.14.2 of the group standard T / CI 1078-2025.

[0114] 3. Peel strength test results

[0115] Table 4

[0116] Note: For specific testing methods, please refer to section 7.13 of the group standard T / CI 1078-2025.

[0117] The test results in Table 2-4 show that, compared with Comparative Example 1, the addition of an external high wear-resistant coating significantly reduced the coating peeling rate of the composite diaphragm, improved the peel strength of the composite diaphragm, and did not affect the surface resistivity of the composite diaphragm.

[0118] As can be seen from the comparison between Example 1 and Examples 5 and 6, the addition of silane coupling agent reduces the coating peeling rate of the composite membrane to a greater extent and improves its peel strength. It also keeps the surface resistivity of the composite membrane at a low level.

[0119] The comparison between Example 1, Example 2, Example 3 and Comparative Example 4 shows that the plasma treatment of PPS support mesh has a certain positive effect on the coating peeling rate and coating peel strength of the diaphragm (Comparative Example 1 and Comparative Example 3 are compared).

[0120] In summary, the PPS support mesh plasma pretreatment technology, the diaphragm coating stepped technology, and the addition of silane coupling agent provided by this invention can significantly improve the strength of the composite diaphragm coating and the adhesion between the coating and the substrate without increasing the surface resistivity of the composite diaphragm. This enhances the composite diaphragm's abrasion resistance, pressure resistance, and resistance to various external impacts in actual working conditions, ensuring the service life of the composite diaphragm, while greatly reducing the production cost of the composite diaphragm.

[0121] The embodiments described above are merely preferred embodiments for fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A method for preparing a highly wear-resistant, stepped-coating alkaline water electrolysis composite diaphragm, characterized in that, Includes the following steps: A support mesh is provided, wherein the support mesh is subjected to corona treatment or low-temperature plasma treatment to obtain a support mesh containing active groups on its surface; An organic polymer solution containing active groups is provided, which is mixed with a first inorganic hydrophilic filler to obtain a highly hydrophilic coating slurry; A high-wear-resistant coating slurry is obtained by mixing an organic polymer solution with a second inorganic hydrophilic filler. The highly hydrophilic coating slurry is coated on both sides of the support mesh fabric containing active groups on the surface to obtain an internal highly hydrophilic coating. After air bathing at 25-30℃ for 3-5 minutes, the highly wear-resistant coating slurry is coated on the internal highly hydrophilic coating to form a highly wear-resistant coating. The phase transformation yields the alkaline electrolytic water composite membrane.

2. The preparation method according to claim 1, characterized in that, The supporting mesh is selected from fabrics, porous membranes or felts made of polytetrafluoroethylene and / or polyphenylene sulfide. The active groups include hydroxyl and / or carboxyl groups; Low-temperature plasma treatment parameters: power 150-300W, treatment time 30-60s; The parameters for the corona treatment are: voltage 12-20kV, electrode gap 2-5mm, operating frequency 15-30Hz, and treatment time 5-30s.

3. The preparation method according to claim 1, characterized in that, The organic polymer containing active groups is selected from hydroxylated polysulfone and / or sulfonated polysulfone; the active groups include one or more of hydroxyl, sulfonic acid, and carboxyl groups; The mass ratio of the organic polymer containing active groups to the first inorganic hydrophilic filler is 1:(2.5-4). The content of organic polymer in the highly hydrophilic coating slurry is 15-18 wt%. The highly hydrophilic coating slurry also includes a first silane crosslinking agent.

4. The preparation method according to claim 3, characterized in that, The first silane crosslinking agent is selected from one or more of epoxy silane coupling agents, alkyl silane coupling agents, and phenyl silane coupling agents; The content of the first silane crosslinking agent in the highly hydrophilic coating slurry is 0.1wt%-0.5wt%.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the organic polymer with strong wear resistance to the second inorganic hydrophilic filler is 1:(1-2.5). Organic polymers with strong wear resistance include polyarylsulfone; The content of the highly wear-resistant organic polymer in the high-wear-resistant coating slurry is 18-21 wt%. The high wear-resistant coating slurry also includes a second silane crosslinking agent; The first inorganic hydrophilic filler and the second inorganic hydrophilic filler are each independently selected from one or more of titanium dioxide, silicon dioxide, cerium dioxide, zirconium dioxide, and hydrotalcite; the particle size range is 20-150.

6. The preparation method according to claim 5, characterized in that, The second silane crosslinking agent is selected from one or more of epoxy silane coupling agents, alkyl silane coupling agents, and phenyl silane coupling agents; The content of the second silane crosslinking agent in the high wear-resistant coating is 0.1wt%-0.5wt%; Phase transformation conditions: Immerse the composite coating in a water bath at 20-60℃ for 5-10 minutes to carry out the phase transformation.

7. A highly wear-resistant, stepped-coating alkaline water electrolysis composite diaphragm, characterized in that, Prepared by the preparation method according to any one of claims 1-6; comprising a substrate support layer and a highly hydrophilic coating disposed on both sides of the substrate support layer, and further comprising a highly wear-resistant coating disposed on the surface of the highly hydrophilic coating; The base support layer is a support mesh fabric; The highly hydrophilic coating comprises an organic polymer containing active groups and a first inorganic hydrophilic filler; The high wear-resistant coating comprises an organic polymer with strong wear resistance and a second inorganic hydrophilic filler.

8. The alkaline electrolytic water composite membrane according to claim 7, characterized in that, The highly hydrophilic coating further includes a first silane crosslinking agent, and the content of the first silane crosslinking agent in the highly hydrophilic coating slurry is 0.1wt%-0.5wt%. The high wear-resistant coating slurry also includes a second silane crosslinking agent, and the content of the second silane crosslinking agent in the high wear-resistant coating is 0.1wt%-0.5wt%.

9. The alkaline water electrolysis composite membrane according to claim 7, characterized in that, The mass ratio of the organic polymer containing active groups to the first inorganic hydrophilic filler is 1:(2.5-4). The mass ratio of the organic polymer with strong wear resistance to the second inorganic hydrophilic filler is 1:(1-2.5). The supporting mesh is selected from fabrics, porous membranes or felts made of polytetrafluoroethylene and / or polyphenylene sulfide containing active groups. The organic polymer containing the active group is selected from hydroxylated polysulfone and / or sulfonated polysulfone; the active group includes one or more of hydroxyl, sulfonic acid and carboxyl groups; The first inorganic hydrophilic filler and the second inorganic hydrophilic filler are each independently selected from one or more of titanium dioxide, silicon dioxide, cerium dioxide, zirconium dioxide, and hydrotalcite; Organic polymers with strong wear resistance include polysulfone.

10. An alkaline water electrolysis device, characterized in that, Includes the highly wear-resistant, stepped-coating alkaline electrolyzed water composite diaphragm as described in any one of claims 7-9.

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