Multilayer crosslinking coupling diaphragm for hydrogen production by electrolysis of water and preparation method thereof

Abstract

The application discloses a multilayer cross-linking coupling diaphragm for hydrogen production by water electrolysis and a preparation method thereof, and belongs to the technical field of hydrogen production by water electrolysis. The method comprises the following steps: forming a polar interface transition layer by using plasma activation to treat a spun fabric, and coating a casting solution containing aminopropyl triethoxysilane and nano zirconium dioxide, and then performing phase conversion and post-processing to obtain the multilayer cross-linking coupling diaphragm. The application solves the problems of low ion conductivity, insufficient air tightness and poor coating stability of a traditional hydrogen production diaphragm to a certain extent by constructing an asymmetric configuration, a chemical bonding interface and a multistage pore structure. The ion conductivity of the obtained multilayer cross-linking coupling diaphragm for hydrogen production by water electrolysis is 0.05 S / cm-0.15 S / cm at 80 DEG C, the air tightness is 0.5 bar-2.0 bar, and the 180 DEG peeling strength between the base film and the functional layer is 5.0 gf / mm-15.0 gf / mm.

Description

Technical Field

[0001] This application belongs to the field of water electrolysis for hydrogen production technology, and specifically relates to a multi-layer cross-linked coupling membrane for water electrolysis for hydrogen production and its preparation method. Background Technology

[0002] Hydrogen energy is an important carrier for building new power systems. Alkaline water electrolysis for hydrogen production is considered a core pathway to achieve large-scale green hydrogen production due to its mature technology and ability to be efficiently coupled with fluctuating renewable energy sources. The membrane, as a key component of the electrolyzer, directly determines the system's energy efficiency, gas purity, and operational lifespan.

[0003] Currently, commercially available membranes (such as PPS membranes and their composite membranes) have significant technical shortcomings. On the one hand, the inherent hydrophobic properties of PPS (polyphenylene sulfide) materials result in low ionic conductivity, and the single-pore structure makes it difficult to simultaneously achieve ion transport and gas barrier properties. On the other hand, traditional composite membranes mainly rely on physical bonding between the support network and the functional coating, resulting in insufficient bonding strength. Under long-term operation and fluctuating conditions, high-concentration alkaline solutions and bubble erosion can easily lead to coating peeling and powdering, causing a sharp decline in performance.

[0004] Therefore, there is an urgent need to produce a membrane for hydrogen production by water electrolysis that can solve problems such as low ion conductivity, poor coating adhesion, and insufficient long-term stability. Summary of the Invention

[0005] The purpose of this application is to provide a multi-level cross-linked coupling membrane for hydrogen production by water electrolysis and its preparation method. Through the synergistic effect of plasma activation and silane cross-linking, a stable base membrane-interface bridge-multi-level functional coating composite structure and multi-level pore system can be constructed. While improving ion conductivity and gas barrier performance, it effectively inhibits the peeling failure of the coating under high temperature and strong alkaline environment.

[0006] To achieve the above objectives, this application provides a multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis. The multi-layered cross-linked coupling membrane includes: The base film is made of at least one of polyphenylene sulfide, sulfonated polyphenylene sulfide, polyarylene sulfide sulfone, polyphenylene sulfide ketone, polyphenylene sulfide amide, and polyphenylene sulfide imide. The functional layer has ≥1 layer. Each functional layer includes a single microporous layer and a single diffusion layer. In each functional layer, the microporous layer is located on the side closer to the base film, and the diffusion layer is located on the side farther from the base film. The pore size of the microporous layer is < the pore size of the diffusion layer. The base film and the functional layer are connected by an interface bridge formed by plasma activation treatment; The multi-layer cross-linked coupling membrane has an ionic conductivity of 0.05 S / cm to 0.15 S / cm at 80℃, an air tightness of 0.5 bar to 2.0 bar, and a 180° peel strength between the base membrane and the functional layer of 5.0 gf / mm to 15.0 gf / mm.

[0007] Furthermore, the thickness of the base film is 250μm~800μm, and the material of the base film is polyphenylene sulfide spun fabric. The pore size of the polyphenylene sulfide spun fabric is 40μm~50μm, and the basis weight is 220g / m³. 2 ~260g / m 2 The air tightness is 400mmH2O~800mmH2O, the warp density is 30 threads / cm~70 threads / cm, and the weft density is 10 threads / cm~50 threads / cm.

[0008] Furthermore, the thickness of a single functional layer is 100μm~600μm, wherein the thickness of the single microporous layer and the single diffusion layer are 100μm~300μm and 100μm~300μm, respectively; the microporous layer has honeycomb micropores with a pore size of 50nm~500nm, and the diffusion layer has finger-shaped macropores with a pore size of 1μm~5μm.

[0009] Furthermore, the pore sizes of the honeycomb micropores or finger-shaped macropores are uniformly set; or, the pore sizes of the honeycomb micropores or finger-shaped macropores are set in a gradient.

[0010] Furthermore, the functional layer is prepared by the following method: casting solutions for the microporous layer and the diffusion layer are prepared separately; the casting solution for the microporous layer is coated onto the surface of the base film and subjected to phase inversion treatment to form the microporous layer; the casting solution for the diffusion layer is coated onto the surface of the microporous layer and subjected to phase inversion treatment to obtain the functional layer; wherein, the polyethylene glycol concentration in the casting solution for the microporous layer is 3wt%~7wt%, and the polyethylene glycol concentration in the casting solution for the diffusion layer is 5wt%~12wt%; the coating thickness of the casting solution for the microporous layer or the diffusion layer is 100μm~1000μm. The casting solution for the microporous layer or the diffusion layer is applied using a blade coating process, and the blade coating gap is controlled to achieve a wet film thickness of 100μm~1000μm; it should be noted that this coating thickness refers to the initial thickness of the wet film during coating, not the final dry film thickness after curing.

[0011] Furthermore, the casting solution for the microporous layer or diffusion layer comprises the following components by mass percentage: 50%~70% N-methylpyrrolidone, N,N-dimethylacetamide or N,N-dimethylformamide, 1%~10% aminopropyltriethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 5%~15% polysulfone, 5%~50% nano-zirconia, 1%~10% polyvinylpyrrolidone, and the balance polyethylene glycol; wherein the particle size of the nano-zirconia is 20nm~50nm; the casting solution is prepared by the following method: mixing the components of the casting solution and stirring in a water bath at 50℃~80℃ for 6h~12h.

[0012] Furthermore, the phase transformation treatment method for the microporous layer coating solution or diffusion layer coating solution is as follows: immerse it in a deionized water coagulation bath at a temperature of 20℃~50℃ and keep it at that temperature for 30min~60min.

[0013] Furthermore, the plasma activation treatment includes: using oxygen or air as the treatment gas, activating the base film for 1 min to 10 min under a vacuum of 10 Pa to 50 Pa and a power of 100 W to 300 W.

[0014] Furthermore, before plasma activation treatment, the base film also includes a pretreatment process, which includes the following steps: ultrasonic cleaning with deionized water and anhydrous ethanol for 25 min to 35 min in sequence, with an ultrasonic power of 400 W to 500 W; drying at 45 °C to 65 °C and under a vacuum of -0.1 MPa for 1.5 h to 8 h; and rolling to remove wrinkles under a pressure of 0.5 MPa to 3.0 MPa.

[0015] This application also provides a method for preparing a multi-layered cross-linked coupling membrane for hydrogen production by water electrolysis, comprising the following steps: forming an interface transition layer with polar functional groups on the surface of a base membrane by plasma activation treatment to obtain an activated thin film; preparing casting solutions for a microporous layer and a diffusion layer respectively; coating the casting solution of the microporous layer onto the surface of the activated thin film, and obtaining an intermediate after phase inversion; coating the casting solution of the diffusion layer onto the surface of the intermediate, and obtaining a membrane precursor after phase inversion; and preparing a multi-layered cross-linked coupling membrane by calendering and drying the membrane precursor. The calendering pressure is 0.2 MPa to 0.5 MPa, the drying temperature is 55°C to 65°C, and the drying time is 20 h to 30 h.

[0016] In summary, this application has the following advantages: This application provides a multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis. Addressing the challenge of balancing ion conductivity, coating adhesion, and long-term alkaline stability in existing water electrolysis membranes, this application utilizes the synergistic effect of plasma activation and silane cross-linking to construct a robust composite structure of base membrane-interface bridge-multi-layered functional coating on the surface of a polyphenylene sulfide (PPS) base membrane. This asymmetric structure features a functional coating on only one side of the base membrane. This functional coating also incorporates a pore system with different pore sizes (a diffusion layer with micron-sized pores and a microporous layer with nano-sized pores), mitigating the coating peeling and performance degradation issues caused by weak physical adsorption bonding in traditional composite membranes. This enhances the interfacial stability and durability of the membrane under harsh conditions of high temperature, strong alkali, and bubble erosion. Simultaneously, the synergistic optimization of this multi-layered structure and multi-level pore design significantly improves the membrane's wettability and ion transport efficiency, achieving a balance between high ion conductivity and excellent gas barrier performance, thereby reducing electrolyzer energy consumption and ensuring gas tightness. Furthermore, the preparation process is mild, easy to operate, and easy to scale up. The novel membrane is better suited to the application requirements of renewable energy hydrogen production and has high industrial application value. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the multi-layered cross-linked coupling membrane for hydrogen production by water electrolysis proposed in this application.

[0019] Figure 2 This is a scanning electron microscope cross-sectional image of the multi-layered cross-linked coupling membrane for hydrogen production by water electrolysis proposed in Example 1 of this application.

[0020] Figure 3 This is a scanning electron microscope cross-sectional image of the multi-layered cross-linked coupling membrane for hydrogen production by water electrolysis proposed in Example 2 of this application.

[0021] Figure 4 This is a comparison chart of the ion conductivity performance of the membranes obtained in the embodiments and comparative examples of this application.

[0022] Figure 5 This is a comparison chart of the ion conductivity stability of the membranes obtained in the embodiments and comparative examples of this application.

[0023] Figure 6 The figures show the water contact angle test results of the diaphragm obtained from the embodiments and comparative examples of this application.

[0024] Figure 7This is a graph showing the alkali stability performance of the diaphragms obtained in the embodiments and comparative examples of this application.

[0025] Figure 8 These are stability performance diagrams of the diaphragm electrolyzers obtained after stability testing in the embodiments and comparative examples of this application. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] As a key core component of the electrolyzer, the diaphragm undertakes the dual functions of conducting hydroxide ions and blocking cross-permeation of hydroxide gases. Its comprehensive performance directly determines the energy efficiency, gas product purity, service life and system safety of the electrolyzer under fluctuating operating conditions. At present, commercially available diaphragms (such as asbestos membranes, polyphenylene sulfide (PPS) membranes, and polyphenylene sulfide composite diaphragms) are difficult to achieve an ideal balance in key performance indicators and have significant technical defects, which restrict the improvement of electrolysis system efficiency and long-term safe operation. For example, PPS diaphragms have the following defects: (1) The inherent hydrophobic properties of PPS materials result in poor wettability with alkaline electrolytes and generally low ionic conductivity (usually below 0.05 S / cm), which directly causes the electrolyzer working voltage to increase and the system energy consumption to increase, which seriously restricts the improvement of electrolysis efficiency. (2) Chemically modified PPS diaphragms have improved hydrophilicity, but the modification effect decays over time. Traditional composite membranes have some shortcomings: (1) The PPS support mesh has low surface energy and strong chemical inertness, making it difficult to establish effective chemical bonds on its surface using traditional processes. The functional coating only bonds with the base membrane through physical adsorption. This interfacial bonding force cannot withstand the long-term chemical erosion of high-concentration alkaline solution on the cathode side and the continuous impact of hydrogen bubbles, which usually leads to the peeling or pulverization of the coating, thereby causing a sharp decline in membrane performance. (2) The existing composite membrane structure and pore design need to be optimized, making it difficult to simultaneously meet the two contradictory requirements of rapid ion transport and efficient gas barrier.

[0028] In summary, existing water electrolysis hydrogen production membranes struggle to simultaneously achieve optimal ion conductivity, coating adhesion, and long-term alkaline stability. Therefore, this application proposes a membrane with superior overall performance: a multi-layered cross-linked coupling membrane for water electrolysis hydrogen production. This application constructs an interface bridge on the anode side based on plasma activation and silane cross-linking, and combines this with a phase separation process to form a functional coating with a multi-layered gradient pore structure, achieving both high ion conductivity and high airtightness. On the cathode side, the excellent thermal stability and alkali corrosion resistance of the base membrane material are fully utilized to maintain its original surface state. Based on the above principles, this application forms an anode-reinforced (i.e., the side of the base membrane coated with the functional layer serves as the anode for the water electrolysis hydrogen production reaction) - cathode-native (i.e., the side of the base membrane uncoated with the functional layer serves as the cathode for the water electrolysis hydrogen production reaction) configuration, effectively overcoming the electrolyzer safety issues caused by the easy detachment of coatings in traditional sandwich-type composite membranes. This application forms a stable asymmetric composite system of base membrane-interface-functional layer, such as... Figure 1 As shown, the base membrane fabric (e.g., PPS) provides overall support, the interface bridge on the anode side achieves strong coupling, and the multi-level porous structure of the functional coating optimizes the mass transfer path. The synergistic effect of these three elements not only significantly improves the ion conduction performance of the membrane, but more importantly, it achieves a breakthrough in long-term operational stability through structural innovation, providing a reliable membrane solution for efficient and long-life electrolytic hydrogen production under the fluctuating conditions of renewable energy.

[0029] Specifically, in the first aspect, this application provides a multi-layer cross-linked coupling membrane for hydrogen production by water electrolysis, comprising: (1) a base membrane, the material of which includes at least one of polyphenylene sulfide, sulfonated polyphenylene sulfide, polyarylene sulfide sulfone, polyphenylene sulfide ketone, polyphenylene sulfide amide, and polyphenylene sulfide imide; (2) a functional layer, the number of functional layers being ≥1, each functional layer comprising a single microporous layer and a single diffusion layer, wherein the microporous layer is located on the side close to the base membrane and the diffusion layer is located on the side away from the base membrane; the pore size of the microporous layer is < the pore size of the diffusion layer; wherein the base membrane and the functional layer are connected by an interface bridge formed by plasma activation treatment; the multi-layer cross-linked coupling membrane has an ionic conductivity of 0.05S / cm~0.15S / cm at 80℃, an air tightness of 0.5bar~2.0bar, and a 180° peel strength between the base membrane and the functional layer of 5.0gf / mm~15.0gf / mm.

[0030] The multi-layer cross-linked coupling diaphragm in this application is used for hydrogen production via water electrolysis. Its base membrane serves as a physical support material and possesses a certain degree of airtightness, ensuring safe operation after an airtightness alarm in the electrolyzer. At least one functional layer structure can be designed on the surface of the base membrane (only one side is configured, the other side does not have a functional layer, preserving the original structural characteristics of the base membrane material). Each functional layer includes a microporous layer and a diffusion layer. That is, when the functional layer structure has at least two layers, the structure of the multi-layer cross-linked coupling diaphragm sequentially includes a base membrane, a microporous layer, a diffusion layer, another microporous layer, a diffusion layer… and so on, with the number of functional layers selected according to the actual application scenario.

[0031] During the hydrogen production process via water electrolysis, hydrogen bubbles (2H₂O + 2e⁻) are continuously generated on the cathode side. - →H2+2OH - This process generates intense dynamic mechanical erosion and localized stress on the diaphragm surface, accompanied by a rapid increase in the concentration of alkali solution on the cathode side. To address this harsh condition, this application innovatively employs an asymmetric structural design, specifically: retaining the intrinsic surface of the polyphenylene sulfide (PPS) fabric on the cathode side, fully utilizing its excellent heat resistance and resistance to strong alkali corrosion to resist physical impact; while on the anode side, constructing an integrated composite system of base film-interface bridge-functional coating, and building a pore structure with different pore sizes through precise control of the phase separation process. Specifically, the upper layer of the functional coating features finger-shaped macropores (pore size approximately 1μm~5μm), which significantly improves the wettability and permeation rate of the electrolyte, ensuring efficient mass transfer; the lower layer presents honeycomb-shaped micropores (pore size 50nm~500nm), forming a highly tortuous ion transport path, ensuring high ionic conductivity while effectively blocking the cross-permeation of hydrogen and oxygen gases through the pore size confinement effect. Furthermore, nano-zirconia (particle size 20nm~50nm) is uniformly dispersed in the polymer network as a functional filler, not only constructing a rapid ion conduction channel, but also synergistically enhancing the mechanical strength and dimensional stability of the coating through strong interfacial interactions with the polysulfone matrix. This synergistic effect of the asymmetric composite structure and the nano-reinforcement mechanism fully leverages the intrinsic stability advantages of the PPS base film, enabling the membrane to achieve an ion conductivity of 0.14S / cm at 80℃, an airtightness exceeding 2.8 bar, and a long-term alkali stability of 99.8%, demonstrating comprehensive performance surpassing traditional composite membranes.

[0032] Preferably, the thickness of the base film is 250μm~800μm, the material of the base film is polyphenylene sulfide fabric, the pore size of the polyphenylene sulfide fabric is 40μm~50μm, and the basis weight is 220g / m³. 2 ~260g / m 2 The air tightness is 400mmH2O~800mmH2O, the warp density is 30 threads / cm~70 threads / cm, and the weft density is 10 threads / cm~50 threads / cm.

[0033] In this application, polyphenylene sulfide (PPS) fabric is preferred as the base membrane material. Through a unique asymmetric structural design, an "interface bridge" based on plasma activation and silane crosslinking is constructed on the anode side, and a functional coating with a multi-layered gradient pore structure is formed using a phase separation process, achieving high ionic conductivity and high airtightness. On the cathode side, the excellent thermal stability and alkali corrosion resistance of PPS material are fully utilized to maintain its original surface state. This innovative "anodine-reinforced - cathode-native" configuration (i.e., an asymmetric structure, with a functional layer constructed only on one side of the base membrane, while the other side retains its original structure) improves the membrane stability problem caused by the failure of the double-sided coating interface in traditional sandwich-type composite membranes to a certain extent, significantly extending their service life.

[0034] In a specific embodiment, the thickness of a single functional layer is 100μm to 600μm, wherein the thicknesses of the single microporous layer and the single diffusion layer are 100μm to 300μm and 100μm to 300μm, respectively. The microporous layer has honeycomb-shaped micropores with a pore size of 50nm to 500nm, and the diffusion layer has finger-shaped macropores with a pore size of 1μm to 5μm. The smaller pore size of the microporous layer provides better gas barrier properties, preventing hydrogen and oxygen from intermingling. The diffusion layer has higher ionic conductivity. The two layers are fixed by a stable connection, enhancing bonding strength, gas barrier performance, and ionic conductivity. In this application, the microporous layer and diffusion layer use the same coating solution material, forming different pore sizes through different amounts of polyethylene glycol. The connection between the diffusion layer and the microporous layer is stable, as is the connection between the functional layer and the base film (interfacial bridge connection formed by plasma activation treatment). Therefore, the multi-layered cross-linked coupling membrane obtained in this application is not easily detached, has good airtightness, and high ionic conductivity.

[0035] In specific embodiments, the pore sizes of the honeycomb micropores or finger-shaped macropores are uniformly arranged; or, the pore sizes of the honeycomb micropores or finger-shaped macropores are gradient arranged. Normally, the micropores and macropores in this application are randomly arranged, but they can also be uniformly or gradient-arranged depending on the actual application. For example, a micropore layer with uniform pore size and a diffusion layer with uniform pore size can be arranged, or a micropore layer with uniform pore size and a diffusion layer with gradient pore size can be arranged, or both the micropore layer and the diffusion layer can be set to gradient pore size. It is understood that when the number of functional layers is greater than one, the structure of the micropore layer and diffusion layer in each layer can also be set using the aforementioned methods.

[0036] In a specific implementation, the functional layer is prepared by the following method: S101. Prepare casting solutions for the microporous layer and the diffusion layer respectively; S102. The casting solution of the microporous layer is coated onto the surface of the base film and then subjected to phase inversion treatment to form a microporous layer; S103. The casting solution for the diffusion layer is coated onto the surface of the microporous layer, followed by phase inversion treatment to obtain the functional layer. The polyethylene glycol concentration in the casting solution for the microporous layer is 3wt%–7wt%, and the polyethylene glycol concentration in the casting solution for the diffusion layer is 5wt%–12wt%. The coating thickness of the casting solution for either the microporous layer or the diffusion layer is 100μm–1000μm. The casting solution is uniformly coated onto one side of the activated base membrane, and the wet film thickness is controlled to determine the final dry coating thickness and pore structure. This process is simple and controllable, allowing for precise adjustment of the membrane's microstructural parameters (thickness, pore size distribution, etc.). It also enables the construction of asymmetric structures, forming a composite functional layer only on one side of the base membrane while retaining the original characteristics of the other side. By controlling the polyethylene glycol concentration, the pore size of the microporous layer and the diffusion layer can be controlled to form nanopores in the microporous layer and micropores in the diffusion layer.

[0037] In a specific embodiment, the casting solution of the microporous layer or diffusion layer comprises the following components by mass percentage: 50%~70% N-methylpyrrolidone, N,N-dimethylacetamide or N,N-dimethylformamide, 1%~10% aminopropyltriethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 5%~15% polysulfone, 5%~50% nano-zirconia, 1%~10% polyvinylpyrrolidone, and the balance polyethylene glycol (preferably, the polyethylene glycol concentration in the casting solution of the microporous layer is 3wt%~7wt%, and the polyethylene glycol concentration in the casting solution of the diffusion layer is 5wt%~12wt%); wherein, the particle size of the nano-zirconia is 20nm~50nm; the casting solution is prepared by the following method: mixing the components of the casting solution and stirring in a water bath at 50℃~80℃ for 6h~12h. In this application, polysulfone, as the film-forming polymer, provides the coating with mechanical strength and a framework; nano-zirconia, as an inorganic functional filler, provides ion conduction channels to enhance mechanical strength and alkali resistance; aminopropyltriethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, as coupling agents, connects one end to the base film and the other end to the polymer after hydrolysis, forming a molecular bridge; polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) act as pore-forming agents, precipitating during phase inversion to form a porous structure. The synergistic effect of these components endows the casting solution with excellent film-forming properties, hydrophilicity, and reactivity. In the coating solution of this application, aminopropyltriethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane can be hydrolyzed in solution to generate silanol. Its silanol groups and polar functional groups on the activated base film surface undergo a condensation reaction to form stable Si-OC covalent bonds. At the same time, the amino groups at the silane end interact strongly with the electron-deficient groups in the polysulfone molecular chain. This process builds a strong molecular bridge between the PPS base film and the hydrophilic functional coating, thereby realizing a fundamental transformation from physical adsorption to chemical bonding.

[0038] In a specific embodiment, the phase transformation treatment method is as follows: immersion in a deionized water coagulation bath at a temperature of 20℃~50℃ for 30min~60min. The deionized water coagulation bath treatment in this application is essentially a phase transformation process. Utilizing the exchange between the solvent (NMP) and the non-solvent (water), the polymer solution undergoes liquid-liquid phase separation, with the polymer-rich phase solidifying into a film and the polymer-poor phase forming pores. By controlling the temperature and time, the phase separation kinetics are controlled, forming a gradient structure transitioning from finger-like pores to honeycomb pores. A multi-level porous structure, either dense at the top and sparse at the bottom or finger-honeycomb-like, spontaneously forms, balancing the contradiction between ion conduction (macropores / finger-like pores) and gas barrier (micropores / honeycomb pores). During this process, silane hydrolysis products undergo a condensation reaction with polar groups on the surface of the base film, forming strong covalent bonds, making the connection between the base film and the functional layer more robust.

[0039] In a specific embodiment, the plasma activation treatment includes: using oxygen or air as the treatment gas, activating the base film for 1 to 10 minutes under a vacuum of 10 Pa to 50 Pa and a power of 100 W to 300 W. This application utilizes high-energy particles (electrons, ions, free radicals, etc.) generated by low-voltage glow discharge to bombard the base film surface, which can produce physical etching to increase the specific surface area; simultaneously, it breaks some CH and CS bonds and introduces oxygen-containing polar functional groups such as hydroxyl (-OH) and carboxyl (-COOH) groups to significantly improve the surface energy of the base film, providing abundant active sites for the subsequent chemical anchoring of silane coupling agents. In this process, taking PPS as an example, the inert hydrophobic PPS surface can be transformed into a hydrophilic surface rich in active sites, thus solving the problem that PPS is difficult to directly chemically bond without damaging the mechanical strength of the substrate material.

[0040] In a specific embodiment, the base film is further subjected to a pretreatment process before plasma activation treatment. The pretreatment includes the following steps: ultrasonic cleaning with deionized water and anhydrous ethanol for 25 min to 35 min in sequence, with an ultrasonic power of 400 W to 500 W; drying at 45 °C to 65 °C and under a vacuum of -0.1 MPa for 1.5 h to 8 h; and rolling to remove wrinkles under a pressure of 0.5 MPa to 3.0 MPa.

[0041] The pretreatment step of this application utilizes the polarity difference between deionized water and ethanol to physically remove impurities such as oil and dust from the surface of the base film through ultrasonic vibration; then vacuum drying removes moisture and solvent from the pores to prevent the generation of bubbles in subsequent processing; and rolling wrinkle removal smooths the surface of the base film, ensuring the uniformity of the coating thickness, thereby significantly improving the cleanliness of the base film, providing a clean interface for subsequent surface activation and coating bonding, eliminating physical defects on the surface of the base film, improving the overall flatness and appearance quality of the diaphragm, and avoiding uneven local current density caused by wrinkles.

[0042] Secondly, based on a general inventive concept, this application also provides a method for preparing a multi-layered cross-linked coupling membrane for hydrogen production by water electrolysis, comprising the following steps: S1. An interfacial transition layer with polar functional groups is formed on the surface of the base film by plasma activation treatment to obtain an activated thin film; S2. Prepare casting solutions for the microporous layer and the diffusion layer respectively; S3. A casting solution coated with a microporous layer is applied to the surface of the activated thin film, and an intermediate is obtained after phase inversion; S4. The casting liquid coated with the diffusion layer is placed on the surface of the intermediate, and after phase inversion, a membrane precursor is obtained; S5. The membrane precursor is calendered and dried to prepare a multi-layer cross-linked coupling membrane.

[0043] In a specific embodiment, the calendering pressure is 0.2 MPa to 0.5 MPa, the drying temperature is 55°C to 65°C, and the drying time is 20 to 30 hours. The roller calendering method of this application further compacts the coating, optimizes the pore structure, and enhances interfacial bonding. Then, vacuum drying thoroughly removes residual solvents and water, stabilizing the composite structure. This not only eliminates internal defects in the coating and improves the density and mechanical strength of the diaphragm, but also stabilizes its dimensions, ensuring that the diaphragm's performance remains unchanged during long-term storage and use.

[0044] In summary, this application first introduces polar groups such as hydroxyl groups through plasma treatment, and then uses a silane coupling agent to effectively chemically anchor the coating on the base film surface, transforming the weak physical adsorption between the coating and the base film in traditional composite membranes into a strong Si-OC covalent bond connection, fundamentally solving the bottleneck of easy peeling of the coating under harsh environments. Next, by controlling the type and ratio of pore-forming agents (PVP, PEG), combined with the temperature and time of the coagulation bath, the thermodynamics and kinetics of the phase transformation process are jointly regulated. Through this synergy, an asymmetric gradient structure of upper finger-shaped macropores and lower honeycomb micropores is generated in situ within the coating. The finger-shaped pores provide low-resistance fast ion channels, while the underlying honeycomb pores provide a highly tortuous gas barrier. This structure perfectly balances the two contradictory performance indicators of high ion conductivity and low gas permeability. Simultaneously, the added nano-zirconia is in situ locked within the polymer network during the phase transformation process, not only providing conductive sites but also enhancing the matrix through physical entanglement and hydrogen bonding with the polysulfone chains. The enhancement methods include: suppressing polymer swelling in long-term alkaline solutions to improve the dimensional stability of the coating; and enhancing conductivity as an ion conduction channel, achieving a simultaneous improvement in mechanical durability and electrochemical activity. The design of this application also includes coating only on one side of the base membrane (typically the anode side), while retaining the original PPS fabric on the other side. This asymmetric design synergizes with the actual operating environment of the electrolyzer. The cathode side (retained side) directly faces the high-concentration alkaline solution and intense hydrogen bubble erosion, utilizing the excellent weather resistance of PPS to resist corrosion; the anode side (coating side) utilizes an optimized hierarchical porous structure for efficient ion conduction. This cleverly avoids the weakness of the sandwich structure double-sided coating, which is prone to failure on the cathode side, significantly extending the service life of the diaphragm under fluctuating power conditions.

[0045] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.

[0046] Example 1 This embodiment provides a method for preparing a multi-layered cross-linked coupling membrane for hydrogen production by water electrolysis, including the following steps: (1) A 300 μm thick PPS fabric was ultrasonically cleaned (450 W, the same below) in deionized water and anhydrous ethanol for 30 min. Then it was dried under vacuum (-0.1 MPa, the same below) at 60℃ for 2 h. Finally, it was wrinkled by rolling at 0.5 MPa pressure to obtain a pretreated PPS film.

[0047] (2) The pretreated PPS membrane is placed in a low-pressure plasma treatment device, oxygen is introduced as the treatment gas, the vacuum degree is controlled at 20 Pa, the treatment power is 150 W, and the treatment time is 5 min. An interface transition layer rich in polar functional groups is formed on the surface of the base membrane to obtain an activated film.

[0048] (3) Prepare casting solutions for the microporous layer and the diffusion layer respectively, wherein, The casting solution for the microporous layer comprises the following components: 50 mL (50 wt%) of N-methylpyrrolidone, 15 g (15 wt%) of polysulfone, 4 g (4 wt%) of polyvinylpyrrolidone, 20 g (20 wt%) of nano-zirconia, 4 g (4 wt%) of aminopropyltriethoxysilane, and 7 g (7 wt%) of polyethylene glycol. The casting solution for the diffusion layer comprises the following components: 50 mL (50 wt%) of N-methylpyrrolidone, 13 g (13 wt%) of polysulfone, 4 g (4 wt%) of polyvinylpyrrolidone, 20 g (20 wt%) of nano-zirconia, 4 g (4 wt%) of aminopropyltriethoxysilane, and 9 g (9 wt%) of polyethylene glycol. The preparation method of the casting solution is as follows: weigh the components of the microporous layer or diffusion layer and place them in a single-necked flask. Heat the flask in a 70°C water bath and stir with a magnetic stirrer until the polysulfone is completely dissolved to form a polymer casting solution.

[0049] (4) The casting solution of the microporous layer is poured onto the surface of the modified activated film, and the film is scraped with a scraper preheated to 70°C. The thickness of the scraped film is controlled to be 200 μm. The film is then immediately placed in deionized water and coagulated in a 20°C coagulation bath for 30 min to complete the phase transformation and obtain the coupling membrane precursor containing the microporous layer.

[0050] (5) Pour the casting solution of the diffusion layer onto the surface of the coupling membrane precursor containing the microporous layer, and use a film scraper preheated to 70°C to scrape the membrane, control the thickness of the scraped membrane to be 200 μm, and immediately place it in deionized water in a 50°C coagulation bath for 10 min to complete the phase transformation, and obtain a multi-layer cross-linked coupling membrane precursor containing the microporous layer and the diffusion layer.

[0051] (6) The multi-layer cross-linked coupling membrane precursor was calendered by a roller press under a pressure of 0.5 MPa, and then dried under vacuum at 60°C for 24 h to obtain a multi-layer cross-linked coupling membrane for hydrogen production by water electrolysis.

[0052] The membrane performance of the multi-layered cross-linked coupling membrane (i.e., comprising a base membrane and a functional layer located on one side of the base membrane) prepared in Example 1 was analyzed and tested (referencing standards: GB / T 45332-2025, GB / T 46104-2025). Experimental results included: alkali absorption rate of 61.7% and porosity of 21.7%. Ionic conductivity was tested under 6M KOH conditions; the ionic conductivity at 25℃ was 0.0278 S / cm, at 80℃ it was 0.1113 S / cm, the ionic conductivity stability at 60℃ reached 80%, the alkali stability reached 99.7% after 500 hours, the water contact angle was 65°, and the airtightness was 3.2 bar (3.14 × 10⁻⁶). 4The coating (mmH2O) has a 180° peel strength of 11.5 gf / mm and a mass retention rate of 95.8% after a 300-hour electrolytic cell stability test.

[0053] Cross-sectional scanning electron microscope image of the multi-layered cross-linked coupling membrane used for hydrogen production by water electrolysis in Example 1 is shown below. Figure 2 As shown, it clearly reveals a multi-layered structure. On the anode side of Example 1, the coating exhibits a distinct multi-level pore gradient distribution: the upper layer is a finger-like macroporous structure, designed to rapidly adsorb and conduct electrolyte, ensuring excellent hydrophilicity; the middle layer transitions to a honeycomb microporous structure, which significantly enhances the gas barrier capacity of the membrane while maintaining a high ion transport rate, thereby effectively inhibiting the transmembrane permeation of hydrogen and oxygen.

[0054] Example 2 This embodiment provides a method for preparing a multi-layered cross-linked coupling membrane for hydrogen production by water electrolysis, including the following steps: (1) A 250 μm thick PPS fabric was ultrasonically cleaned in deionized water and anhydrous ethanol for 30 min. Then it was dried under vacuum at 60 °C for 2 h, and then wrinkled by rolling at 0.5 MPa pressure to obtain a pretreated PPS film.

[0055] (2) The pretreated PPS membrane is placed in a low-pressure plasma treatment device, oxygen is introduced as the treatment gas, the vacuum degree is controlled at 10 Pa, the treatment power is 150 W, and the treatment time is 3 min. An interface transition layer rich in polar functional groups is formed on the surface of the base membrane to obtain an activated film.

[0056] (3) Prepare casting solutions for the microporous layer and the diffusion layer respectively, wherein, The casting solution for the microporous layer comprises the following components: 70 mL (70 wt%) of N-methylpyrrolidone, 7 g (7 wt%) of polysulfone, 2 g (2 wt%) of polyvinylpyrrolidone, 15 g (15 wt%) of nano-zirconia, 3 g (3 wt%) of aminopropyltriethoxysilane, and 3 g (3 wt%) of polyethylene glycol. The casting solution for the diffusion layer comprises the following components: 70 mL (70 wt%) of N-methylpyrrolidone, 5 g (5 wt%) of polysulfone, 2 g (2 wt%) of polyvinylpyrrolidone, 15 g (15 wt%) of nano-zirconia, 3 g (3 wt%) of aminopropyltriethoxysilane, and 5 g (5 wt%) of polyethylene glycol. The preparation method of the casting solution is as follows: weigh the components of the microporous layer or diffusion layer and place them in a single-necked flask. Heat the flask in a 70°C water bath and stir with a magnetic stirrer until the polysulfone is completely dissolved to form a polymer casting solution.

[0057] (4) The casting solution of the microporous layer is poured onto the surface of the modified activated film, and the film is scraped with a scraper preheated to 70°C. The thickness of the scraped film is controlled to be 200 μm. The film is then immediately placed in deionized water and coagulated in a 20°C coagulation bath for 30 min to complete the phase transformation and obtain the coupling membrane precursor containing the microporous layer.

[0058] (5) Pour the casting solution of the diffusion layer onto the surface of the coupling membrane precursor containing the microporous layer, and use a film scraper preheated to 70°C to scrape the membrane, control the thickness of the scraped membrane to be 200 μm, and immediately place it in deionized water in a coagulation bath at 20°C for 30 min to complete the phase transformation, and obtain a multi-layer cross-linked coupling membrane precursor containing the microporous layer and the diffusion layer.

[0059] (6) The multi-layer cross-linked coupling membrane precursor was calendered by a roller press under a pressure of 0.3 MPa, and then dried under vacuum at 60°C for 24 h to obtain a multi-layer cross-linked coupling membrane for hydrogen production by water electrolysis.

[0060] The multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis prepared in Example 2 was tested for membrane performance according to the method described in Example 1. The test results included: alkali absorption rate of 80.2% and porosity of 33.4%. Ionic conductivity (6M KOH): 0.035 S / cm at 25℃, 0.140 S / cm at 80℃, 90% stability at 60℃, 99.8% alkali stability after 500 hours, and an airtightness of 2.8 bar (2.74 × 10⁻⁶). 4 The functional layer has a 180° peel strength of 13.0 gf / mm and a mass retention rate of 97.1% after a 300-hour electrolytic cell stability test.

[0061] Cross-sectional scanning electron microscope image of the multi-layered cross-linked coupling membrane used for hydrogen production by water electrolysis in Example 2 is shown below. Figure 3As shown, a distinct hierarchical porous structure is exhibited, which becomes more pronounced as the polysulfone content decreases. It can be observed that the coating material fully fills the pores of the PPS base film, which not only strengthens the matrix but also forms a continuous ion conduction channel. This structure is achieved through an innovative design that precisely controls the polymer content and phase transformation kinetics in the casting solution. Under lower polymer content conditions, the mass transfer driving force of the casting solution system is enhanced, resulting in a much higher exchange rate between the surface solvent and the coagulation bath than in the interior, thus establishing a mass transfer rate gradient from the surface to the interior of the coating. This kinetic gradient directly leads to a gradient distribution of pore size: in the surface region where the coating contacts the coagulation bath, rapid mass transfer induces the formation of finger-like macropores, greatly promoting instantaneous wetting and continuous transport of the electrolyte; while inside the coating, the mass transfer rate gradually slows down, the phase separation process becomes more controllable, and a dense, uniformly sized honeycomb microporous network is formed. This kinetic calibration of "fast-slow" phase separation from the outside to the inside is the core mechanism for achieving the pore size gradient in this application. This hierarchical porous structure exhibits clear functional zoning: the upper layer of finger-shaped macropores facilitates rapid wetting and transport of the electrolyte; while the middle layer of honeycomb-shaped micropores, with their high specific surface area and dense characteristics, provides excellent gas barrier performance while maintaining high ionic conductivity, thereby effectively suppressing transmembrane crosstalk between hydrogen and oxygen.

[0062] Example 3 This embodiment provides a method for preparing a multi-layered cross-linked coupling membrane for hydrogen production by water electrolysis, including the following steps: (1) A PPS fabric with a thickness of 800 μm was ultrasonically cleaned in deionized water and anhydrous ethanol for 30 min. Then it was dried under vacuum at 60 °C for 2 h, and then wrinkled under 1 MPa pressure using a roller press to obtain a pretreated PPS film.

[0063] (2) The pretreated PPS membrane is placed in a low-pressure plasma treatment device, oxygen is introduced as the treatment gas, the vacuum degree is controlled at 50 Pa, the treatment power is 300 W, and the treatment time is 10 min. An interface transition layer rich in polar functional groups is formed on the surface of the base film to obtain an activated film.

[0064] (3) Prepare casting solutions for the microporous layer and the diffusion layer respectively, wherein, The casting solution for the microporous layer comprises the following components: 50 mL (50 wt%) of N-methylpyrrolidone, 15 g (15 wt%) of polysulfone, 4 g (4 wt%) of polyvinylpyrrolidone, 20 g (20 wt%) of nano-zirconia, 4 g (4 wt%) of aminopropyltriethoxysilane, and 7 g (7 wt%) of polyethylene glycol. The casting solution for the diffusion layer comprises the following components: 50 mL (50 wt%) of N-methylpyrrolidone, 10 g (10 wt%) of polysulfone, 4 g (4 wt%) of polyvinylpyrrolidone, 20 g (20 wt%) of nano-zirconia, 4 g (4 wt%) of aminopropyltriethoxysilane, and 12 g (12 wt%) of polyethylene glycol. The preparation method of the casting solution is as follows: weigh the components of the microporous layer or diffusion layer and place them in a single-necked flask. Heat the flask in a 70°C water bath and stir with a magnetic stirrer until the polysulfone is completely dissolved to form a polymer casting solution.

[0065] (4) The casting solution of the microporous layer is poured onto the surface of the modified activated film, and the film is scraped with a scraper preheated to 70°C. The thickness of the scraped film is controlled to be 200 μm. The film is then immediately placed in deionized water and coagulated in a 40°C coagulation bath for 40 min to complete the phase transformation and obtain the coupling membrane precursor containing the microporous layer.

[0066] (5) Pour the casting solution of the diffusion layer onto the surface of the coupling membrane precursor containing the microporous layer, and use a film scraper preheated to 70°C to scrape the membrane, control the thickness of the scraped membrane to be 200 μm, and immediately place it in deionized water in a coagulation bath at 40°C for 40 min to complete the phase transformation, and obtain a multi-layer cross-linked coupling membrane precursor containing the microporous layer and the diffusion layer.

[0067] (6) The multi-layer cross-linked coupling membrane precursor was calendered by a roller press under a pressure of 0.5 MPa, and then dried under vacuum at 60°C for 24 h to obtain a multi-layer cross-linked coupling membrane for hydrogen production by water electrolysis.

[0068] The multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis prepared in Example 3 was tested for membrane performance according to the method described in Example 1. The test results included: alkali absorption rate of 73.6% and porosity of 29.5%. Ionic conductivity (6M KOH): 0.030 S / cm at 25℃, 0.120 S / cm at 80℃, 85% stability at 60℃, 99.4% alkali stability after 500 hours, and an airtightness of 2.5 bar (2.55 × 10⁻⁶). 4 The 180° peel strength of the functional layer is 12.0 gf / mm (mmH2O).

[0069] Example 4 The difference between this embodiment and Embodiment 1 is that the same two functional layers are set in the base film monolayer, and the process and component content of each part are the same as in Embodiment 1.

[0070] The multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis prepared in Example 4 was tested for membrane performance according to the method described in Example 1. The test results included: alkali absorption rate of 59.6% and porosity of 24.5%. Ionic conductivity (6M KOH): 0.025 S / cm at 25℃, 0.120 S / cm at 80℃, 87% stability at 60℃, 99.5% alkali stability after 500 hours, and an airtightness of 2.6 bar (2.65 × 10⁻⁶). 4 The functional layer has a 180° peel strength of 10.0 gf / mm (mmH2O).

[0071] Comparative Example 1 This comparative example uses a commercial PPS membrane provided by Zhejiang Jiafeili Company. The membrane was immersed in a 3M KOH solution for 24 hours to complete the alkali doping and obtain a conventional KOH / PPS membrane.

[0072] The conventional KOH / PPS membrane obtained in Comparative Example 1 was tested for membrane performance according to the method in Example 1. The results are as follows: alkali absorption rate was 15.3%, porosity was 8.47%, ionic conductivity in 6M KOH solution was 0.0068 S / cm at 25℃ and 0.0507 S / cm at 80℃, ionic conductivity stability was 50% at 60℃, alkali stability was 95.71% after 500h, water contact angle was 104°, and air tightness was 400 mm H2O.

[0073] Comparative Example 2 This comparative example uses a commercially available PPS composite membrane provided by Carbon Energy Technology Co., Ltd., which is immersed in a 3M KOH solution for 24 hours to complete alkali doping and obtain the PPS composite membrane.

[0074] The PPS composite membrane obtained in Comparative Example 2 was tested for membrane performance according to the method in Example 1. The results are as follows: alkali absorption rate was 40.5%, porosity was 39.76%, ionic conductivity (6M KOH): 0.031 S / cm at 25℃, 0.13 S / cm at 80℃, ionic conductivity stability reached 80% at 60℃, alkali stability reached 97.79% after 500h, and air tightness was 2.0 bar (2.0 × 10⁻⁶). 4 The mass retention rate of mmH2O after a 300-hour electrolytic cell stability test was 93.1%.

[0075] Comparative Example 3 The difference between this comparative example and Example 1 is that aminopropyltriethoxysilane (KH-550) was not used in the coating solution.

[0076] The PPS composite membrane obtained in Comparative Example 3 was tested for membrane performance according to the method in Example 1. The results are as follows: alkali absorption rate was 58.5%, porosity was 28.2%, ionic conductivity (6M KOH): 0.029 S / cm at 25℃, 0.12 S / cm at 80℃, ionic conductivity stability reached 88.5% at 60℃, alkali stability reached 96.0% after 500h, and air tightness was 2.1 bar (2.14 × 10⁻⁶). 4 The functional layer has a 180° peel strength of 8.0 gf / mm (mmH2O).

[0077] Comparative Example 4 The difference between this comparative example and Example 1 is that only a microporous layer is provided, and no diffusion layer is provided.

[0078] The PPS composite membrane obtained in Comparative Example 4 was tested for membrane performance according to the method in Example 1. The results are as follows: alkali absorption rate was 45.5%, porosity was 20.6%, ionic conductivity (6M KOH): 0.023 S / cm at 25℃, 0.10 S / cm at 80℃, ionic conductivity stability reached 80.5% at 60℃, alkali stability reached 97.3% after 500h, and air tightness was 1.8 bar (1.84 × 10⁻⁶). 4 mmH2O).

[0079] Comparative Example 5 The difference between this comparative example and Example 1 is that only a diffusion layer is provided, and no microporous layer is provided.

[0080] The PPS composite membrane obtained in Comparative Example 3 was tested for membrane performance according to the method in Example 1. The results are as follows: alkali absorption rate was 50.2%, porosity was 28.54%, ionic conductivity (6M KOH): 0.029 S / cm at 25℃, 0.125 S / cm at 80℃, ionic conductivity stability reached 82.5% at 60℃, alkali stability reached 97.6% after 500h, and air tightness was 1.5 bar (1.53 × 10⁻⁶). 4 mmH2O).

[0081] The composite membranes obtained in Examples 1-4 and Comparative Examples 1-5 were tested for alkali absorption rate and analyzed for porosity. The results are shown in Table 1. The ionic conductivity performance of some examples and comparative examples is as follows: Figure 4 As shown, the stability of ionic conductivity is as follows: Figure 5 As shown in the figure, the water contact angle test diagram is as follows: Figure 6 As shown in the figure, the alkali stability performance is as follows: Figure 7 and Figure 8As shown, the multi-layered cross-linked coupling membrane exhibits significantly better ionic conductivity, stability, hydrophilicity, and alkali stability than the comparative example.

[0082] Table 1. Results of Alkali Absorption Rate and Porosity Analysis

[0083] In summary, this application has at least the following advantages: (1) This application breaks through the limitations of the traditional sandwich-type composite diaphragm symmetrical structure and constructs an asymmetric configuration with enhanced anode function and intrinsically stable cathode. On the anode side, a stable integrated composite system of base film-interface bridge-functional coating is constructed through plasma activation and silane crosslinking technology; while on the cathode side, the intrinsic surface of polyphenylene sulfide (PPS) fabric is retained, making full use of its excellent heat resistance and strong alkali corrosion resistance. This configuration effectively avoids the problem of interface peeling and swelling failure of the cathode-side coating of traditional diaphragms under high concentration of alkaline solution and bubble scouring, and achieves a breakthrough in the stability of the diaphragm in long-term dynamic operation.

[0084] (2) This application achieves synergistic enhancement of mechanical and electrochemical properties by constructing a polysulfone / nanozirconia composite coating. The functional coating is prepared by solvent-inducible phase separation (NIPS) and utilizes the strong interfacial interaction between nanozirconia and the polysulfone matrix to form an interpenetrating network structure. The uniformly dispersed nanozirconia not only constructs efficient fast ion conduction channels and significantly improves ion conductivity, but also effectively enhances the mechanical strength and dimensional stability of the coating as a nano-reinforcement, thus achieving a more ideal balance between high conductivity and excellent hermeticity.

[0085] (3) This application constructs a gradient pore structure in situ within the functional coating by precisely controlling the composition of the casting solution and the phase transformation process parameters. This structure consists of upper finger-shaped macropores and lower honeycomb micropores (this positional relationship description does not limit the positional relationship between the functional layer and the base film; it only indicates the positional relationship between the microporous layer and the diffusion layer in the upper functional layer structure when the base film is used as the substrate). The upper macroporous structure (1μm~5μm) significantly improves the wettability of the membrane and the electrolyte permeation rate, ensuring a high alkali absorption rate (up to 80.2%). The lower microporous structure (50nm~500nm) increases the gas permeation resistance by utilizing the pore size confinement effect, effectively blocking the cross-linking of hydrogen and oxygen gases. This multi-level pore structure design achieves synergistic optimization of rapid electrolyte transport and efficient gas barrier.

[0086] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are interpreted only to include the preferred embodiments and all changes and modifications falling within the scope of this application.

[0087] Finally, it should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes the element.

[0088] This application uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis, characterized in that, The multi-layered cross-linked coupling membrane includes: The base film, wherein the material of the woven base film includes at least one of polyphenylene sulfide, sulfonated polyphenylene sulfide, polyarylene sulfide sulfone, polyphenylene sulfide ketone, polyphenylene sulfide amide, and polyphenylene sulfide imide. The functional layer has ≥1 layer, and each functional layer includes a single microporous layer and a single diffusion layer. In each functional layer, the microporous layer is located on the side close to the base film, and the diffusion layer is located on the side away from the base film. The pore size of the microporous layer is < the pore size of the diffusion layer. The base film and the functional layer are connected by an interface bridge formed by plasma activation treatment; The multi-layer cross-linked coupling diaphragm has an ionic conductivity of 0.05 S / cm to 0.15 S / cm at 80°C, an air tightness of 0.5 bar to 2.0 bar, and a 180° peel strength between the base film and the functional layer of 5.0 gf / mm to 15.0 gf / mm.

2. The multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis according to claim 1, characterized in that, The thickness of the base film is 250μm~800μm, the material of the base film is polyphenylene sulfide, the pore size of the polyphenylene sulfide fabric is 40μm~50μm, and the basis weight is 220g / m². 2 ~260g / m 2 The air tightness is 400mmH2O~800mmH2O, the warp density is 30 threads / cm~70 threads / cm, and the weft density is 10 threads / cm~50 threads / cm.

3. The multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis according to claim 1, characterized in that, The thickness of a single functional layer is 100μm~600μm, wherein the thicknesses of the single microporous layer and the single diffusion layer are 100μm~300μm and 100μm~300μm, respectively. The microporous layer has honeycomb-shaped micropores with a pore size of 50nm to 500nm, and the diffusion layer has finger-shaped macropores with a pore size of 1μm to 5μm.

4. The multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis according to claim 1, characterized in that, The honeycomb-shaped micropores or the finger-shaped macropores are uniformly arranged in diameter; Alternatively, the pore size gradient of the honeycomb micropores or the finger-shaped macropores may be provided.

5. The multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis according to claim 1, characterized in that, The functional layer is prepared by the following method: The casting solutions for preparing the microporous layer and the diffusion layer are prepared separately; The casting solution of the microporous layer is coated onto the surface of the base film and then subjected to phase inversion treatment to form the microporous layer. The casting solution of the diffusion layer is coated onto the surface of the microporous layer, and then subjected to phase inversion treatment to obtain the functional layer; wherein, The polyethylene glycol concentration in the casting solution of the microporous layer is 3wt%~7wt%, and the polyethylene glycol concentration in the casting solution of the diffusion layer is 5wt%~12wt%. In this process, the gap between the blades is controlled during each coat to achieve a wet film thickness of 100μm to 1000μm.

6. The multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis according to claim 5, characterized in that, The casting solution of the microporous layer or the diffusion layer comprises the following components by mass percentage: 50%~70% N-methylpyrrolidone, N,N-dimethylacetamide or N,N-dimethylformamide, 1%~10% aminopropyltriethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 5%~15% polysulfone, 5%~50% nano-zirconium dioxide, 1%~10% polyvinylpyrrolidone, and the balance polyethylene glycol; wherein... The casting solution is prepared by mixing the components of the casting solution and stirring it in a water bath at 50℃~80℃ for 6h~12h.

7. The multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis according to claim 5, characterized in that, The phase transformation treatment method is as follows: immerse the sample in a deionized water coagulation bath at a temperature of 20℃~50℃ and keep it at that temperature for 10min~100min.

8. The multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis according to claim 1, characterized in that, The plasma activation treatment includes: using oxygen or air as the treatment gas, activating the base film for 1 min to 10 min under a vacuum of 10 Pa to 50 Pa and a power of 100 W to 300 W.

9. The multi-layered cross-linked coupling membrane for hydrogen production via water electrolysis according to claim 1 or 8, characterized in that, Before plasma activation treatment, the base film also includes a pretreatment process, wherein the pretreatment includes the following steps: The product is ultrasonically cleaned with deionized water and anhydrous ethanol for 25-35 minutes at a power of 400-500W; dried at 45-65℃ and -0.1MPa vacuum for 1.5-8 hours; and rolled to remove wrinkles under a pressure of 0.5-3.0MPa.

10. A method for preparing a multi-layered cross-linked coupling membrane for hydrogen production by water electrolysis according to any one of claims 1-9, characterized in that, Includes the following steps: An activated thin film is obtained by forming an interfacial transition layer with polar functional groups on the surface of the base film through plasma activation treatment. Casting solutions for preparing the microporous layer and the diffusion layer were prepared separately. A casting solution coated with the microporous layer is applied to the surface of the activated thin film, and an intermediate is obtained after phase inversion. A casting solution coated with the diffusion layer is applied to the surface of the intermediate, and after phase inversion, a membrane precursor is obtained. The membrane precursor is subjected to calendering and drying processes to prepare a multi-layered cross-linked coupling membrane.

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