High-safety multilayer-structure composite diaphragm for alkaline water electrolysis and preparation method of high-safety multilayer-structure composite diaphragm

Abstract

The invention discloses a high-safety multilayer structure composite diaphragm for alkaline water electrolysis and a preparation method of the high-safety multilayer structure composite diaphragm. The method comprises the following steps: carrying out sulfonation modification on polyphenylene sulfide fabric to obtain sulfonated polyphenylene sulfide fabric; the preparation method comprises the following steps: dissolving polysulfone, a pore-foaming agent, hydrophilic inorganic nanoparticles and a functionalized nano material in a solvent to obtain a homogeneous membrane casting solution; uniformly coating one surface of sulfonated polyphenylene sulfide fabric with the membrane casting solution, and enabling the membrane casting solution to permeate into the polyphenylene sulfide fabric from the surface to obtain a wet composite membrane; carrying out pre-evaporation treatment on the wet composite diaphragm to obtain a wet composite diaphragm with a compact skin layer; and carrying out phase inversion on the wet composite diaphragm with the compact skin layer to obtain the composite diaphragm. According to the invention, the sulfonated polyphenylene sulfide fabric diaphragm with a complete structure is used as a support body, and the single surface is coated with the organic / inorganic membrane casting solution to prepare the high-safety multilayer-structure composite diaphragm, so that the safety of hydrogen production by alkaline water electrolysis can be effectively enhanced.

Description

Technical Field

[0001] This invention relates to the field of membrane materials technology, specifically to a high-safety multilayer composite membrane for alkaline water electrolysis and its preparation method. Background Technology

[0002] Alkaline water electrolysis is a crucial technology for achieving green hydrogen production, with core components including electrodes, catalysts, and membranes. Traditional membranes, such as polyphenylene sulfide (PPS) fabric membranes, suffer from high sheet resistance and poor gas barrier properties, making them unsuitable for efficient and stable industrial applications. Current research on fabric membranes primarily focuses on enhancing fiber hydrophilicity through surface modification methods such as sulfonation, oxidative grafting, and quaternization, as seen in the literature "Yifei Wang, Xinyi Huo, Mao Peng, Mengfei Zhang, Xingyu Liu, Jinli Zhang, Wei Li. Superhydrophilic polyphenylene sulfide membrane with enhanced ion transfer for alkaline water electrolysis. International Journal of Hydrogen Energy, 65 (2024) 872-880." However, due to inherent defects in the fabric structure, these methods cannot fundamentally improve the insufficient gas barrier performance.

[0003] Organic / inorganic hybrid composite membranes exhibit relatively low sheet resistance and high gas tightness, but suffer from poor safety. Commercially available composite membranes often experience performance degradation and safety hazards due to the shedding of the polymer matrix and inorganic nano-additives, limiting their widespread application. Currently, research on the safety of composite membranes is extensive, but most work remains focused on improving commercially available composite membranes, specifically enhancing the overall mechanical properties by strengthening the organic / inorganic interface bonding strength based on their existing structures and formulations. For example, the paper "Miao Guo, Song Wen, Yunyong Tang, Kunmei Su, Maliang Zhang, Zhenhuan Li. Effect of porous irregular ZrO2 nanoparticles on the performance of alkaline water electrolysis composite separator membranes under complex conditions. Journal of Membrane Science, 713 (2025), 123332." describes a method to enhance the mechanical coupling between porous irregular zirconium dioxide nanoparticles and the organic matrix. While such improvements can enhance mechanical properties to some extent, they fail to completely eliminate the risk of hydrogen permeation caused by matrix layer shedding.

[0004] Therefore, there is an urgent need to develop a diaphragm for alkaline water electrolysis with high gas barrier performance and high safety. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-safety multilayer composite membrane for alkaline water electrolysis and its preparation method.

[0006] The technical solution of this invention to solve the aforementioned technical problem is to provide a method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis, characterized in that the method includes the following steps: Step 1: Sulfonate the polyphenylene sulfide fabric to obtain sulfonated polyphenylene sulfide fabric; Polysulfone, pore-forming agent, hydrophilic inorganic nanoparticles and functionalized nanomaterials are dissolved in a solvent to obtain a homogeneous casting solution; Step 2: Apply the casting solution evenly to one surface of the sulfonated polyphenylene sulfide fabric, allowing the casting solution to penetrate from the surface into the interior of the polyphenylene sulfide fabric to obtain a wet composite membrane. Step 3: Pre-evaporate the wet composite membrane obtained in Step 2 to obtain a wet composite membrane with a dense skin layer; Step 4: The wet composite membrane with a dense skin layer is subjected to phase transformation to obtain a high-safety multilayer composite membrane for alkaline water electrolysis.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Overall structural innovation, achieving synergistic performance and industrial breakthrough: The design creatively combines a complete sulfonated polyphenylene sulfide fabric substrate with a dense microporous polysulfone functional layer to form a novel integrated "substrate-functional layer" structure. This design fundamentally solves the industry problems of poor air tightness of traditional fabric diaphragms and insufficient mechanical strength and excessive reliance on interface integrity for safety of traditional composite diaphragms. It achieves for the first time the unity of high mechanical strength, excellent gas barrier properties and high-efficiency ion transport, providing an innovative solution to the bottleneck in industrial applications.

[0008] (2) Unique safety redundancy mechanism, significantly improving intrinsic safety and long-term stability: Using sulfonated polyphenylene sulfide fabric with a complete structure as the supporting substrate throughout, a "double protection" mechanism is constructed. Even if the functional layer is partially detached or damaged under long-term extreme operating conditions, the sulfonated polyphenylene sulfide fabric with a complete structure at the bottom can still serve as an independent physical barrier to maintain basic airtightness. This eliminates the risk of gas cross-contamination caused by partial or overall failure of the coating from the design source, providing a safety redundancy that existing technologies do not have, and ensuring the long-term service safety of the diaphragm in high-temperature and strong alkaline environments.

[0009] (3) The air tightness is fundamentally improved and reliably guaranteed: By using a single-sided composite dense microporous polysulfone layer, a continuous, defect-free, and highly efficient gas barrier layer is provided for the porous fabric substrate, directly overcoming the core technical bottleneck of poor air tightness of the fabric membrane. Moreover, the single-sided composite method takes into account both process controllability and cost.

[0010] (4) Excellent mechanical properties and high structural reliability: The composite membrane uses intrinsically high-strength and high-toughness polyphenylene sulfide fabric as the overall support skeleton, which enables the composite membrane to have mechanical properties far exceeding those of traditional coated composite membranes, ensuring the dimensional stability and structural reliability of the membrane during assembly and long-term operation.

[0011] (5) High ion conduction efficiency and reduced system energy consumption: By designing and adding specific functionalized nanomaterials in the functional layer, a highly efficient ion transport channel is constructed, which significantly improves the affinity and conductivity of hydroxide ions, effectively reduces the membrane surface resistance, thereby increasing the current density and voltage efficiency of the electrolyzer and reducing the overall hydrogen production energy consumption.

[0012] (6) High interfacial bonding strength ensures long-term stable operation: Sulfonation treatment of polyphenylene sulfide fabric not only improves hydrophilicity, but also introduces micro-roughness and active groups on the fiber surface, which greatly enhances the physical interlocking and chemical bonding force between the fiber and the functional layer. The interfacial strength far exceeds that of conventional treatment methods. This ensures the long-term integrity of the composite structure under harsh electrolytic environment and lays the foundation for stable performance.

[0013] (7) Deep optimization of hydrophilicity and electrolytic performance: Sulfonation treatment enables the fabric to have rapid electrolyte wetting ability. Combined with the hydrophilic design of the functional layer, the overall hydrophilicity of the diaphragm is optimized, ensuring the effective establishment and continuous stability of the electrolytic reaction interface.

[0014] (8) Collaborative solution to multiple technical problems, with outstanding comprehensive advantages: Through integrated structural design, this invention overcomes multiple defects of traditional diaphragms, such as insufficient air tightness, poor mechanical properties, high risk of interface failure, and limited ion conduction, and achieves complementary and synergistic effects of various performances, demonstrating significant comprehensive technical progress and practical value. Attached Figure Description

[0015] Figure 1 This is a schematic cross-sectional view of the composite diaphragm prepared according to the present invention; Figure 2 This is a cross-sectional electron microscope image of the composite membrane prepared in Example 1 of the present invention; Figure 3 The graph shows the test results of the alkaline electrolysis performance of the composite membranes prepared in Examples 1-6 and the membranes in Comparative Examples 1-2 of this invention. Figure 4 The graph shows the test results of the average tensile strength of the composite membranes prepared in Examples 1-6 and the membranes in Comparative Examples 1-2 of the present invention. Figure 5 The diagram shows the purity of hydrogen produced by the electrolysis of the composite membranes prepared in Examples 1-6 and Comparative Examples 1-2. Detailed Implementation

[0016] Specific embodiments of the present invention are given below. These specific embodiments are only used to further illustrate the present invention in detail and do not limit the scope of protection of the present invention.

[0017] This invention provides a method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis (hereinafter referred to as the method), characterized in that the method includes the following steps: Step 1: Sulfonate the polyphenylene sulfide fabric to improve its hydrophilicity and obtain sulfonated polyphenylene sulfide fabric. Preparation of casting solution: Polysulfone, pore-forming agent, hydrophilic inorganic nanoparticles and functionalized nanomaterials are dissolved in solvent to obtain a homogeneous casting solution; Preferably, in step 1, the thickness of the polyphenylene sulfide fabric is 400~900μm, and the fabric structure is plain weave or satin weave.

[0018] Preferably, in step 1, the sulfonation modification specifically involves: immersing the polyphenylene sulfide fabric in a sulfonating agent to carry out a sulfonation reaction; the sulfonating agent is a sulfuric acid solution with a concentration of 60~90 vol%, the reaction temperature is 40~80℃, and the time is 5~10 h.

[0019] Preferably, in step 1, the mass percentage of each component in the casting solution is: polysulfone 7~15 wt.%, pore-forming agent 1~6 wt.%, hydrophilic inorganic nanoparticles 30~60 wt.%, functionalized nanomaterials 1~9 wt.%, solvent 40~50 wt.%, and the sum of each component is 100%.

[0020] Preferably, in step 1, the pore-forming agent is polyvinylpyrrolidone or polyethylene glycol.

[0021] Preferably, in step 1, the hydrophilic inorganic nanoparticles are at least one of zirconium dioxide, titanium dioxide, cerium dioxide, and magnesium hydroxide nanoparticles.

[0022] Preferably, in step 1, the functionalized nanomaterial is a hydroxylated nanomaterial, preferably at least one of hydroxylated zirconium oxide nanoparticles, hydroxylated alumina nanoparticles, and hydroxylated carbon nanotubes.

[0023] Preferably, in step 1, the solvent is DMAC (N,N-dimethylacetamide) or DMF (N,N-dimethylformamide).

[0024] Preferably, in step 1, the dissolution process involves stirring at room temperature (20-30°C) for 10-24 hours at a speed of 200-1000 rpm. Stirring is preferably performed using a magnetic stirrer.

[0025] Step 2: Apply the casting solution evenly to one surface of the sulfonated polyphenylene sulfide fabric, allowing the casting solution to penetrate from the surface into the interior of the polyphenylene sulfide fabric to obtain a wet composite membrane. Preferably, in step 2, uniform coating is achieved by scraping with a scraper.

[0026] Preferably, in step 2, the casting solution penetrates from the surface to 1 / 2 to 1 / 4 (preferably 1 / 3) of the thickness of the sulfonated polyphenylene sulfide fabric (in this embodiment, the casting solution penetrates from the surface into the sulfonated polyphenylene sulfide fabric 100 to 300 μm along the thickness direction of the sulfonated polyphenylene sulfide fabric).

[0027] Step 3, Pre-evaporation treatment process: The wet composite membrane obtained in step 2 is subjected to pre-evaporation treatment to evaporate part of the solvent on the surface of the casting liquid, forming a dense surface layer, thus obtaining a wet composite membrane with a dense skin layer. Preferably, in step 3, the pre-evaporation process is: temperature 50~90℃, time 30~60s.

[0028] Step 4: The wet composite membrane with a dense skin layer is subjected to phase transformation to obtain a high-safety multilayer composite membrane for alkaline water electrolysis.

[0029] Preferably, in step 4, the phase inversion process is as follows: the wet composite membrane with a dense skin layer is immersed in a phase inversion solution; the phase inversion solution is a mixture of water and ethanol, and the mass of ethanol is 10~30 wt.% of the mass of the mixture; the immersion temperature is room temperature, and the immersion time is 10~60 s.

[0030] Preferably, in step 4, during the phase transformation process, the polysulfone in the casting solution solidifies, the pore-forming agent and solvent dissolve in water, the ethanol content is used to adjust the phase transformation rate, and the polysulfone separates from the pore-forming agent and solvent to form a dense porous structure layer; the dense porous structure layer includes a dense skin layer and a functional pore layer from the surface layer to the inner layer; the functional pore layer has finger-like micropores and sponge-like micropores.

[0031] Preferably, in step 4, the high-safety multilayer composite membrane for alkaline water electrolysis is dried at 50~60℃ and then stored.

[0032] This invention also provides a method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis (hereinafter referred to as the composite membrane). The high-safety multilayer composite membrane for alkaline water electrolysis is characterized by comprising a dense skin layer, a functional porous layer, and a sulfonated polyphenylene sulfide fabric, from the surface to the innermost layer. The functional porous layer contains finger-like micropores and sponge-like micropores. The dense skin layer provides efficient gas barrier performance. The functional porous layer provides high gas barrier performance and low surface resistivity. The finger-like micropores provide electrolyte filling space. The sponge-like micropores, interspersed with the finger-like micropores, provide a tortuous gas permeation path. The finger-like micropores and sponge-like micropores work synergistically to reduce surface resistivity while ensuring good gas tightness. The sulfonated polyphenylene sulfide fabric provides high mechanical properties and stability, while also providing safety redundancy, ensuring safe hydrogen production even if the porous structure layer detaches.

[0033] The present invention also provides an application of the high-safety multilayer composite membrane for alkaline water electrolysis, characterized in that it is applied to the production of hydrogen by alkaline water electrolysis.

[0034] Example 1: (1) A plain weave polyphenylene sulfide fabric with a thickness of 600 μm was immersed in an 80 vol% sulfuric acid solution and sulfonated at 60 °C for 6 h to obtain a sulfonated polyphenylene sulfide fabric. Polysulfone particles, polyvinylpyrrolidone powder, zirconium dioxide nanoparticles, hydroxylated carbon nanotubes and DMAC were stirred at 10:4:40:1:45 at room temperature and 1000 rpm for 12 h. After standing to remove bubbles, a homogeneous casting solution was obtained. (2) Using a scraper, the casting solution is evenly applied to one surface of the sulfonated polyphenylene sulfide fabric, so that the casting solution penetrates into the sulfonated polyphenylene sulfide fabric 200μm from the surface along the thickness direction of the sulfonated polyphenylene sulfide fabric to obtain a wet composite membrane. (3) The wet composite membrane is placed in a 65°C oven for 60s of pre-evaporation treatment to obtain a wet composite membrane with a dense skin layer. (4) At room temperature, the wet composite membrane with a dense skin layer is immersed in a mixed solution of water and ethanol for 60s for phase inversion. The mass of ethanol is 10wt.% of the mass of the mixed solution, and a high-safety multilayer composite membrane for alkaline water electrolysis is obtained.

[0035] Example 2: (1) A plain weave polyphenylene sulfide fabric with a thickness of 600 μm was immersed in a 75 vol% sulfuric acid solution and sulfonated at 60 °C for 8 h to obtain a sulfonated polyphenylene sulfide fabric. Polysulfone particles, polyvinylpyrrolidone powder, zirconium dioxide nanoparticles, hydroxylated alumina nanoparticles and DMAC were stirred at room temperature and 900 rpm for 15 h at a mass ratio of 9:4:40:2:45, and then allowed to stand to remove bubbles to obtain a homogeneous casting solution. (2) Using a scraper, the casting solution is evenly applied to one surface of the sulfonated polyphenylene sulfide fabric, so that the casting solution penetrates into the sulfonated polyphenylene sulfide fabric 200μm from the surface along the thickness direction of the sulfonated polyphenylene sulfide fabric to obtain a wet composite membrane. (3) The wet composite membrane is placed in a 65°C oven for 60s of pre-evaporation treatment to obtain a wet composite membrane with a dense skin layer. (4) At room temperature, the wet composite membrane with a dense skin layer is immersed in a mixed solution of water and ethanol for 60s for phase inversion. The mass of ethanol is 10wt.% of the mass of the mixed solution, and a high-safety multilayer composite membrane for alkaline water electrolysis is obtained.

[0036] Example 3: (1) A plain weave polyphenylene sulfide fabric with a thickness of 600 μm was immersed in a 75 vol% sulfuric acid solution and sulfonated at 60 °C for 7 h to obtain a sulfonated polyphenylene sulfide fabric. Polysulfone particles, polyvinylpyrrolidone powder, zirconium dioxide nanoparticles, hydroxylated zirconium oxide nanoparticles and DMAC were stirred at 1000 rpm for 12 h at room temperature in a mass ratio of 9:3:40:3:45, and then allowed to stand to remove bubbles to obtain a homogeneous casting solution. (2) Using a scraper, the casting solution is evenly applied to one surface of the sulfonated polyphenylene sulfide fabric, so that the casting solution penetrates into the sulfonated polyphenylene sulfide fabric 200μm from the surface along the thickness direction of the sulfonated polyphenylene sulfide fabric to obtain a wet composite membrane. (3) The wet composite membrane is placed in a 75°C oven for 60 seconds of pre-evaporation treatment to obtain a wet composite membrane with a dense skin layer. (4) At room temperature, the wet composite membrane with a dense skin layer is immersed in a mixed solution of water and ethanol for 60s for phase inversion. The mass of ethanol is 30wt.% of the mass of the mixed solution, and a high-safety multilayer composite membrane for alkaline water electrolysis is obtained.

[0037] Example 4: (1) A plain weave polyphenylene sulfide fabric with a thickness of 600 μm was immersed in an 85 vol% sulfuric acid solution and sulfonated at 60 °C for 6 h to obtain a sulfonated polyphenylene sulfide fabric. Polysulfone particles, polyvinylpyrrolidone powder, zirconium dioxide nanoparticles, hydroxylated alumina nanoparticles and DMAC were stirred at room temperature and 800 rpm for 18 h in a mass ratio of 9:2:40:6:43, and then allowed to stand to remove bubbles to obtain a homogeneous casting solution. (2) Using a scraper, the casting solution is evenly applied to one surface of the sulfonated polyphenylene sulfide fabric, so that the casting solution penetrates into the sulfonated polyphenylene sulfide fabric 200μm from the surface along the thickness direction of the sulfonated polyphenylene sulfide fabric to obtain a wet composite membrane. (3) The wet composite membrane is placed in a 75°C oven for 60 seconds of pre-evaporation treatment to obtain a wet composite membrane with a dense skin layer. (4) At room temperature, the wet composite membrane with a dense skin layer is immersed in a mixed solution of water and ethanol for 60s for phase inversion. The mass of ethanol is 20wt.% of the mass of the mixed solution, and a high-safety multilayer composite membrane for alkaline water electrolysis is obtained.

[0038] Example 5: (1) A plain weave polyphenylene sulfide fabric with a thickness of 400 μm was immersed in an 85 vol% sulfuric acid solution and sulfonated at 60 °C for 5.5 h to obtain a sulfonated polyphenylene sulfide fabric. Polysulfone particles, polyvinylpyrrolidone powder, zirconium dioxide nanoparticles, hydroxylated zirconium oxide nanoparticles and DMAC were stirred at room temperature and 700 rpm for 20 h in a mass ratio of 10:3:41:6:40, and then allowed to stand to remove bubbles to obtain a homogeneous casting solution. (2) Using a scraper, the casting solution is evenly applied to one surface of the sulfonated polyphenylene sulfide fabric, so that the casting solution penetrates into the sulfonated polyphenylene sulfide fabric 100μm from the surface along the thickness direction of the sulfonated polyphenylene sulfide fabric to obtain a wet composite membrane. (3) The wet composite membrane is placed in an 80℃ oven for 50s pre-evaporation treatment to obtain a wet composite membrane with a dense skin layer. (4) At room temperature, the wet composite membrane with a dense skin layer is immersed in a mixed solution of water and ethanol for 60s for phase inversion. The mass of ethanol is 20wt.% of the mass of the mixed solution, and a high-safety multilayer composite membrane for alkaline water electrolysis is obtained.

[0039] Example 6: (1) A plain weave polyphenylene sulfide fabric with a thickness of 400 μm was immersed in a 90 vol% sulfuric acid solution and sulfonated at 50 °C for 7 h to obtain a sulfonated polyphenylene sulfide fabric. Polysulfone particles, polyvinylpyrrolidone powder, zirconium dioxide nanoparticles, hydroxylated alumina nanoparticles and DMAC were stirred at room temperature and 700 rpm for 22 h at a mass ratio of 8:3:41:8:40, and then allowed to stand to remove bubbles to obtain a homogeneous casting solution. (2) Using a scraper, the casting solution is evenly applied to one surface of the sulfonated polyphenylene sulfide fabric, so that the casting solution penetrates into the sulfonated polyphenylene sulfide fabric 150μm from the surface along the thickness direction of the sulfonated polyphenylene sulfide fabric to obtain a wet composite membrane. (3) The wet composite membrane is placed in a 70°C oven for 60 seconds of pre-evaporation treatment to obtain a wet composite membrane with a dense skin layer. (4) At room temperature, the wet composite membrane with a dense skin layer is immersed in a mixed solution of water and ethanol for 60s for phase inversion. The mass of ethanol is 10wt.% of the mass of the mixed solution, and a high-safety multilayer composite membrane for alkaline water electrolysis is obtained.

[0040] Comparative Example 1: Comparative Example 1 uses a TORCON® PPS diaphragm, purchased from TORAY.

[0041] Comparative Example 2: Comparative Example 2 uses JL-730 diaphragm, purchased from Tianjin Jinlun New Material Technology Co., Ltd.

[0042] The following tests were performed on Examples 1-6 and Comparative Examples 1-2: Test 1: The diaphragm was placed in the electrolytic cell unit for electrolysis testing. The electrolyte was a 30 wt.% potassium hydroxide aqueous solution, and the temperature was set to 80℃. A pure nickel mesh was used as the anode, and nickel-molybdenum foam was used as the cathode. The voltage was set to 2V, and the current density during electrolysis was measured.

[0043] Test 2: Diaphragm tensile mechanical strength test, refer to national standard GB / T 36363-2018.

[0044] Test 3: The diaphragm was placed in the electrolytic cell unit for electrolysis testing. The electrolyte was a 30% (w / w) potassium hydroxide aqueous solution, and the temperature was set to 80℃. A pure nickel mesh was used as the anode, and nickel-molybdenum foam was used as the cathode. The current density was set to 0.5 A / cm². 2 The purity of the hydrogen produced by electrolysis was determined.

[0045] Depend on Figure 3 It can be seen that the composite membranes prepared in Examples 1-6 exhibit higher current densities in alkaline electrolysis tests compared to the membranes in Comparative Examples 1-2. Higher current densities indicate better electrolytic performance of the membrane.

[0046] Depend on Figure 4 It can be seen that the composite membranes prepared in Examples 1-6 have higher tensile strength compared with the membranes in Comparative Examples 1-2. Higher tensile strength indicates better mechanical properties of the membrane.

[0047] Depend on Figure 5 It can be seen that the composite membranes prepared in Examples 1-6 produce hydrogen with higher purity in alkaline electrolysis tests compared to the membranes in Comparative Examples 1-2. Higher purity of the hydrogen produced by electrolysis indicates better membrane airtightness.

[0048] Table 1 shows the property characterization and performance test results of the composite membranes prepared in Examples 1-6 and the membranes in Comparative Examples 1-2.

[0049] Table 1

[0050] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis, characterized in that, The method includes the following steps: Step 1: Sulfonate the polyphenylene sulfide fabric to obtain sulfonated polyphenylene sulfide fabric; Polysulfone, pore-forming agent, hydrophilic inorganic nanoparticles and functionalized nanomaterials are dissolved in a solvent to obtain a homogeneous casting solution; Step 2: Apply the casting solution evenly to one surface of the sulfonated polyphenylene sulfide fabric, allowing the casting solution to penetrate from the surface into the interior of the polyphenylene sulfide fabric to obtain a wet composite membrane. Step 3: Pre-evaporate the wet composite membrane obtained in Step 2 to obtain a wet composite membrane with a dense skin layer; Step 4: The wet composite membrane with a dense skin layer is subjected to phase transformation to obtain a high-safety multilayer composite membrane for alkaline water electrolysis.

2. The method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis according to claim 1, characterized in that, In step 1, the thickness of the polyphenylene sulfide fabric is 400~900μm, and the fabric structure is plain weave or satin weave.

3. The method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis according to claim 1, characterized in that, In step 1, the sulfonation modification specifically involves immersing the polyphenylene sulfide fabric in a sulfonating agent for sulfonation reaction; the sulfonating agent is a sulfuric acid solution with a concentration of 60~90 vol%, the reaction temperature is 40~80℃, and the reaction time is 5~10 h.

4. The method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis according to claim 1, characterized in that, In step 1, the mass percentage of each component in the casting solution is as follows: polysulfone 7~15 wt.%, pore-forming agent 1~6 wt.%, hydrophilic inorganic nanoparticles 30~60 wt.%, functionalized nanomaterials 1~9 wt.%, solvent 40~50 wt.%, and the sum of each component is 100%.

5. The method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis according to claim 1 or 4, characterized in that, In step 1, the pore-forming agent is polyvinylpyrrolidone or polyethylene glycol; In step 1, the hydrophilic inorganic nanoparticles are at least one of zirconium dioxide, titanium dioxide, cerium dioxide, and magnesium hydroxide nanoparticles; In step 1, the functionalized nanomaterial is a hydroxylated nanomaterial, preferably at least one of hydroxylated zirconium oxide nanoparticles, hydroxylated alumina nanoparticles, and hydroxylated carbon nanotubes. In step 1, the solvent is DMAC or DMF.

6. The method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis according to claim 1, characterized in that, In step 1, the dissolution process is as follows: stirring is used, the stirring temperature is room temperature, the stirring time is 10~24h, and the stirring speed is 200~1000rpm.

7. The method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis according to claim 1, characterized in that, In step 2, the coating is applied evenly using a scraper. In step 2, the casting solution penetrates from the surface to 1 / 2 to 1 / 4 of the thickness of the sulfonated polyphenylene sulfide fabric.

8. The method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis according to claim 1, characterized in that, In step 3, the pre-evaporation process is as follows: temperature is 50~90℃, and time is 30~60s.

9. The method for preparing a high-safety multilayer composite membrane for alkaline water electrolysis according to claim 1, characterized in that, In step 4, the phase inversion process is as follows: the wet composite membrane with a dense skin layer is immersed in a phase inversion solution; the phase inversion solution is a mixture of water and ethanol, and the mass of ethanol is 10~30 wt.% of the mass of the mixture; the immersion temperature is room temperature and the immersion time is 10~60 s.

10. A high-safety multilayer composite membrane for alkaline water electrolysis prepared by the method of any one of claims 1-9, characterized in that, The composite membrane comprises a dense skin layer, a functional porous layer, and a sulfonated polyphenylene sulfide fabric, from the outer layer to the inner layer; the functional porous layer has finger-like micropores and sponge-like micropores. The dense skin layer provides high gas barrier performance; the functional porous layer provides high gas barrier performance and low surface resistivity; the finger-like micropores provide electrolyte filling space; The sponge-like micropores, interspersed with the finger-like micropores, provide a tortuous gas permeation path; The synergistic effect of finger-like and sponge-like micropores reduces surface resistivity while ensuring good airtightness; sulfonated polyphenylene sulfide fabric provides high mechanical properties and stability, while also providing safety redundancy.

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