Slurry for organic-inorganic composite diaphragm, preparation method and application thereof

Abstract

The application provides a slurry for an organic-inorganic composite diaphragm and a preparation method and application thereof, and relates to the technical field of hydrogen production by water electrolysis.The slurry for the organic-inorganic composite diaphragm comprises a solid phase component and a liquid phase component, the solid phase component comprises LDH nanosheets, a binder and a pore-forming agent, the mass proportion of the LDH nanosheets in the slurry is 40-60%, the thickness h of the LDH nanosheets is 10-100 nm, and the average lateral size D of the LDH nanosheets is 50-2000 nm.The slurry for the organic-inorganic composite diaphragm with the layered double metal hydroxide nanosheets with specific sizes as core functional fillers successfully prepares a composite diaphragm with low surface resistance, high bubble point pressure, high mechanical strength, excellent insulation and good stability, and can be widely applied to alkaline water electrolysis devices, can significantly reduce electrolysis energy consumption, and can improve hydrogen purity and device operation stability.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production, and in particular to a slurry for an organic-inorganic composite membrane, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, as a clean and renewable secondary energy source, plays a key role in energy transition. Alkaline water electrolysis technology is one of the mainstream methods for producing hydrogen by water electrolysis due to its maturity, reliability, and strong adaptability to scale. In this technology, the diaphragm is the core component, and its performance directly affects the efficiency, gas purity, safety, and service life of the electrolyzer. An ideal alkaline water electrolysis diaphragm should have the following characteristics: (1) high ionic conductivity to reduce ohmic losses and improve energy efficiency; (2) excellent gas barrier performance to prevent hydrogen and oxygen gas interpenetration and ensure hydrogen purity and operational safety; (3) good mechanical strength and dimensional stability to withstand the assembly pressure of the electrolyzer and physical stress during long-term operation; (4) excellent chemical stability and resistance to strong alkali corrosion; (5) good insulation to prevent short circuits caused by electronic conduction. Traditional asbestos membranes have been gradually phased out due to environmental and health concerns. While commercially available polymer-based composite membranes (such as the ZIRFON series) have made some progress, there is still room for improvement in reducing sheet resistance, enhancing gas barrier properties, and improving long-term operational stability.

[0003] The prior art CN115125582 A discloses a method for preparing an organic-inorganic composite membrane in an alkaline electrolysis device, which uses inorganic particles and layered bimetallic oxide (LDH) to reduce the membrane resistance. However, on the one hand, it does not have the synergistic improvement effect of reducing surface resistance, improving gas barrier properties and long-term operational stability, and on the other hand, it has not been proven to have the relevant improvement effect. Summary of the Invention

[0004] This invention addresses the shortcomings of polymer-based composite membranes currently used in alkaline electrolysis devices, such as high sheet resistance, poor gas barrier properties, and poor long-term operational stability. It provides an organic-inorganic composite membrane slurry that, through the synergistic effect of specific LDH nanosheets and a polymer matrix, constructs an ideal microstructure within the membrane. This simultaneously meets various stringent requirements of alkaline water electrolysis membranes, achieving at least one of the synergistic improvement effects of reducing sheet resistance, enhancing gas barrier properties, and improving long-term operational stability.

[0005] Another object of the present invention is to provide a method for preparing a slurry for an organic-inorganic composite diaphragm.

[0006] Another object of the present invention is to provide an organic-inorganic composite membrane.

[0007] Another object of the present invention is to provide an alkaline water electrolysis device.

[0008] In a first aspect, the present invention specifically protects a slurry for an organic-inorganic composite membrane, comprising a solid phase component and a liquid phase component, wherein the solid phase component comprises LDH nanosheets, a binder and a pore-forming agent; The LDH nanosheets account for 40-60% of the mass of the slurry; The LDH nanosheets have a thickness h of 10~100 nm and an average lateral dimension D of 50~2000 nm.

[0009] According to the organic-inorganic composite membrane slurry protected by the present invention, preferably, the thickness h of the LDH nanosheets and the average transverse dimension D satisfy: 2≤D / h≤40.

[0010] According to the organic-inorganic composite membrane slurry protected by the present invention, preferably, the thickness h of the LDH nanosheets is 10~30 nm and the average lateral dimension D is 50~200 nm.

[0011] According to the organic-inorganic composite membrane slurry protected by the present invention, preferably, the LDH nanosheets are composed of a mixture of two LDH nanosheets with different lateral dimensions, wherein the average lateral dimension D1 of the smaller LDH nanosheets and the average lateral dimension D2 of the larger LDH nanosheets satisfy: D2 / D1>4.

[0012] According to the organic-inorganic composite membrane slurry protected by the present invention, preferably, the mass ratio of the small-sized LDH nanosheets to the large-sized LDH nanosheets is 1~3:10.

[0013] According to the organic-inorganic composite membrane slurry protected by the present invention, preferably, the mass ratio of the liquid phase component to the LDH nanosheets is 0.5~0.9:1.

[0014] A slurry for an organic-inorganic composite membrane according to the present invention preferably satisfies at least one of the following characteristics: a. The LDH nanosheets are selected from at least one of magnesium aluminum hydrotalcite, zinc aluminum hydrotalcite, nickel iron hydrotalcite, and calcium aluminum hydrotalcite; b. The binder is selected from at least one of polysulfone, polyethersulfone, polyarylsulfone, polyacrylonitrile, and chitosan, and preferably the binder accounts for 10-20% of the mass of the slurry; c. The pore-forming agent is selected from at least one of polyvinylpyrrolidone, polyethylene glycol, and polyethylene oxide-polypropylene oxide block copolymer, and preferably the pore-forming agent accounts for 1-5% of the mass of the slurry; d. The liquid phase component is selected from at least one of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide.

[0015] Secondly, the present invention also specifically protects a method for preparing a slurry for an organic-inorganic composite diaphragm, comprising the following steps: The binder and pore-forming agent are added to the liquid phase component and stirred to dissolve. Then, LDH nanosheets are added and stirred for 2-5 hours to obtain the organic-inorganic composite membrane slurry.

[0016] Thirdly, the present invention also specifically protects an organic-inorganic composite membrane, which is prepared by a non-solvent-induced phase separation method, wherein the casting solution used is the slurry for the organic-inorganic composite membrane.

[0017] According to the organic-inorganic composite membrane protected by the present invention, preferably, the organic-inorganic composite membrane has one of the following characteristics: a. The sheet resistivity of the organic-inorganic composite membrane is 0.1~0.2 Ωcm. 2 ; b. The bubble point pressure of the organic-inorganic composite diaphragm is 15~25 bar; c. The tensile strength of the organic-inorganic composite diaphragm is 58~65MPa.

[0018] Fourthly, the present invention also specifically protects an alkaline water electrolysis device, including the aforementioned organic-inorganic composite membrane.

[0019] Beneficial effects: This invention provides an organic-inorganic composite membrane slurry, which uses layered bimetallic hydroxide nanosheets of a specific size as the core functional filler. By precisely controlling the thickness, lateral size, and addition amount of LDH nanosheets, their morphology and distribution in the slurry and the final membrane are controlled. This successfully prepares a composite membrane with low surface resistivity, high bubble point pressure, high mechanical strength, excellent insulation, and good stability. It can be widely used in alkaline water electrolysis devices, which can significantly reduce electrolysis energy consumption and improve hydrogen purity and device operation stability. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a cross-sectional view of the organic-inorganic composite membrane in Example 1. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] The raw materials used in the embodiments and comparative examples of this invention are described below: Polysulfone (PSF, Polysulfone, Solvay) has an average molecular weight of approximately 80,000; Polyethersulfone (PES) has an average molecular weight of approximately 60,000. Polyvinylpyrrolidone (PVP) has an average molecular weight of approximately 40,000.

[0024] The LDH nanosheets used were purchased from a professional nanomaterials company (Xianfeng Nano), and their dimensions were statistically determined using transmission electron microscopy and atomic force microscopy.

[0025] In a specific embodiment, the present invention provides a slurry for an organic-inorganic composite membrane, comprising a solid phase component and a liquid phase component, wherein the solid phase component comprises LDH nanosheets, a binder, and a pore-forming agent; The LDH nanosheets account for 40-60% of the mass of the slurry; The LDH nanosheets have a thickness h of 10~100 nm and an average lateral dimension D of 50~2000 nm.

[0026] It should be noted that: Layered bimetallic hydroxides (LDHs) are a class of two-dimensional nanomaterials composed of positively charged metal hydroxide layers bonded to interlayer anions via non-covalent bonds. LDH materials possess characteristics such as tunable layer composition, exchangeable interlayer ions, large specific surface area, and abundant hydroxyl groups, making them highly promising in catalysis, adsorption, ion exchange, and polymer composites. Introducing LDHs into polymer membranes in the form of nanosheets can utilize their regular two-dimensional channels to promote selective ion transport. Their layered structure can also effectively extend the gas permeation path, thereby simultaneously improving ion conductivity and gas barrier properties. Furthermore, by controlling the size, aspect ratio, dispersion state, and interfacial interactions between the LDH nanosheets and the polymer matrix, an ideal microstructure can be constructed within the membrane, simultaneously meeting various stringent requirements of alkaline water electrolysis membranes.

[0027] LDH nanosheets have a thickness of 20–100 nm and a lateral dimension of 50–2000 nm. Nanosheets within this size range are easily dispersed in slurry and undergo a certain degree of directional alignment during film formation, which is beneficial for forming ordered transport channels throughout the film. The mass percentage of LDH nanosheets in the slurry is 40–60%. If the LDH content is too low, it cannot fully exert its role in constructing ion channels and blocking gases; if the content is too high, the slurry viscosity is too high, making film formation difficult and increasing film brittleness, thus affecting mechanical strength.

[0028] This invention provides an organic-inorganic composite membrane slurry with layered bimetallic hydroxide nanosheets of a specific size as the core functional filler. By precisely controlling the thickness, lateral size and addition amount of LDH nanosheets, their morphology and distribution in the slurry and the final membrane are controlled, and a composite membrane with low surface resistivity, high bubble point pressure, high mechanical strength, excellent insulation and good stability is successfully prepared.

[0029] In some specific embodiments, in order to further improve the gas barrier performance of the diaphragm, the thickness h of the LDH nanosheets mentioned in this invention and the average transverse dimension D satisfy: 2≤D / h≤40.

[0030] LDH nanosheets have a suitable aspect ratio, making them easier to orient in the membrane plane under shear forces (such as during the coating process). This not only helps reduce the resistance to in-plane ion transport, but also forms tortuous barrier paths in the thickness direction through the stacking and overlapping of the sheets, significantly improving the gas barrier performance of the membrane.

[0031] For example, in some specific exemplary embodiments, the D / h value of the thickness h and the average lateral dimension D of the LDH nanosheet mentioned in this invention can be a point value such as 2, 5, 8, 10, 15, 20, 25, 30, 35, 40, or any range of values.

[0032] In some specific embodiments, the thickness h of the LDH nanosheets mentioned in this invention is preferably 10~30 nm, for example, it can be a point value of 10 nm, 15 nm, 20 nm, 25 nm, 30 nm or any range of values. The average lateral dimension D is preferably 50~200 nm, for example, it can be a point value of 50 nm, 80 nm, 100 nm, 150 nm, 180 nm, 200 nm or any range of values.

[0033] In some embodiments, the LDH nanosheets mentioned in this invention are composed of a mixture of two LDH nanosheets with different lateral dimensions, wherein the average lateral dimension D1 of the smaller LDH nanosheet and the average lateral dimension D2 of the larger LDH nanosheet satisfy the condition: D2 / D1>4.

[0034] In some specific embodiments, a more preferred mass ratio of small-sized LDH nanosheets to large-sized LDH nanosheets is 1 to 3:10, for example, it can be a point value such as 1:10, 2:10, 3:10 or any range of values.

[0035] Compared to single-sized LDH nanosheets, the combination of LDH nanosheets of different sizes results in the following: larger LDH nanosheets serve as the framework, dominating the formation of the main supporting structure of the membrane and the main ion transport channel; while smaller LDH nanosheets can fill the gaps between the larger sheets, refining the pore size, blocking defects, enhancing gas barrier properties, and improving mechanical integrity.

[0036] In some specific embodiments, the mass ratio of the liquid phase component to the LDH nanosheets in the slurry for the organic-inorganic composite membrane mentioned in this invention is 0.5~0.9:1, for example, it can be a point value of 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or any range of values. Preferably, controlling the mass ratio of the liquid phase component to the LDH nanosheets in the slurry for the organic-inorganic composite membrane ensures that the slurry has suitable rheological properties, guaranteeing sufficient wetting and dispersion of the LDH nanosheets, while avoiding a loose structure and reduced strength after film formation due to excessive solvent.

[0037] In some specific embodiments, the LDH nanosheets in the organic-inorganic composite membrane slurry mentioned in this invention are selected from at least one of magnesium aluminum hydrotalcite, zinc aluminum hydrotalcite, nickel iron hydrotalcite, and calcium aluminum hydrotalcite.

[0038] The aforementioned preferred LDH nanosheets exhibit excellent chemical stability in a strongly alkaline environment, and their surface properties facilitate their bonding with the polymer matrix, making it more advantageous to prepare composite membranes with good stability.

[0039] In some specific embodiments, the binder in the organic-inorganic composite diaphragm slurry mentioned in this invention is selected from at least one of polysulfone, polyethersulfone, polyarylsulfone, polyacrylonitrile, and chitosan. Preferably, the mass percentage of the binder in the slurry is 10-20%, for example, it can be a point value such as 10%, 12%, 15%, 18%, 20%, or any range of values.

[0040] The role of the binder is to firmly bond the LDH nanosheets together and provide a continuous polymer phase, giving the membrane basic mechanical strength and flexibility. The aforementioned binder polymer has good chemical stability under strong alkaline conditions and excellent film-forming properties. Combined with dosage control, better film-forming performance can be achieved.

[0041] In some specific embodiments, the pore-forming agent in the slurry for organic-inorganic composite diaphragms mentioned in this invention is selected from at least one of polyvinylpyrrolidone, polyethylene glycol, and polyethylene oxide-polypropylene oxide block copolymer. Preferably, the mass percentage of the pore-forming agent in the slurry is 1 to 5%, for example, it can be a point value such as 1%, 2%, 3%, 4%, 5% or any range of values.

[0042] Pore-forming agents are leached out during phase inversion, leaving pores within the membrane, which are crucial for forming a continuous porous structure and reducing ion transport resistance. Optimal selection of the type and amount of pore-forming agent further improves the uniformity and stability of the slurry.

[0043] In some specific embodiments, the liquid phase component in the slurry for organic-inorganic composite membranes mentioned in this invention is selected from at least one of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide. Preferably, the mass percentage of the liquid phase component in the slurry is 28-35%, for example, it can be a point value of 28%, 30%, 32%, 35%, or any range of values.

[0044] The solvents described above have good dissolving power for the selected polymer binders and can effectively wet LDH nanosheets.

[0045] In a specific embodiment, the present invention also provides a method for preparing a slurry for an organic-inorganic composite diaphragm, comprising the following steps: The binder and pore-forming agent are added to the liquid phase component and stirred to dissolve. Then, LDH nanosheets are added and stirred for 2-5 hours to obtain the organic-inorganic composite membrane slurry.

[0046] In some specific exemplary embodiments, the preparation method of the organic-inorganic composite diaphragm slurry mentioned in this invention can be referred to in detail below: First, the binder and pore-forming agent are added to the selected liquid phase component and stirred continuously at room temperature until the polymer is completely dissolved, resulting in a uniform, transparent, viscous solution.

[0047] Subsequently, LDH nanosheets are gradually added to the above solution. During or after the addition process, stirring is continued for 2–5 hours to ensure that the LDH nanosheets are fully dispersed and their surfaces are well coated with the polymer solution, ultimately resulting in a stable slurry with uniform viscosity and no obvious agglomerates.

[0048] If necessary, degassing can be performed to remove air bubbles introduced during the stirring process.

[0049] In a specific embodiment, the present invention also provides an organic-inorganic composite membrane, which is prepared by a non-solvent-induced phase separation method, wherein the casting solution used is the slurry for the organic-inorganic composite membrane.

[0050] In some specific exemplary embodiments, the preparation method of the organic-inorganic composite membrane mentioned in this invention can be specifically referred to as follows: The organic-inorganic composite membrane slurry of the present invention is coated onto a porous support, and the organic-inorganic composite membrane is obtained by phase inversion, washing and drying processes.

[0051] The porous support can be, for example, one of PP (polypropylene) mesh, PPS (polyphenylene sulfide) mesh, or PE (polyethylene) mesh.

[0052] In some specific exemplary embodiments, the preparation method of the organic-inorganic composite separator of the present invention is detailed below: The slurry is uniformly coated onto the surface of a porous support (such as PP mesh, PPS mesh, PE mesh) by means of scraping, dipping or casting, and the wet film thickness is controlled to be 500~700μm, preferably 600μm; Subsequently, the coated membrane is rapidly immersed in a non-solvent (usually water) for phase inversion. During the phase inversion, the solvent (the solvent in the slurry) exchanges with the non-solvent, the polymer precipitates and solidifies from the solution, LDH nanosheets are solidified within the polymer network of the slurry, and the pore-forming agent is leached out to form pores. After sufficient phase inversion, the resulting wet membrane is repeatedly washed with deionized water or hot water to thoroughly remove residual solvent and pore-forming agent. Finally, drying is performed to obtain the final organic-inorganic composite membrane.

[0053] In some specific embodiments, the organic-inorganic composite diaphragm provided by the present invention is a composite diaphragm that combines low surface resistivity, high bubble point pressure, high mechanical strength, excellent insulation and good stability.

[0054] For example, the sheet resistivity of the organic-inorganic composite membrane mentioned in this invention is 0.1~0.2 Ωcm. 2 The bubble point pressure is 15~25 bar, and the tensile strength is 58~65 MPa.

[0055] In a specific embodiment, the present invention also provides an alkaline water electrolysis device, including the aforementioned organic-inorganic composite membrane.

[0056] In some specific exemplary embodiments, the alkaline water electrolysis device mentioned in this invention includes the aforementioned organic-inorganic composite membrane. This device typically also includes an electrolytic cell, an anode, a cathode, a power supply, and a circulation system. The composite membrane of this invention, as the core component separating the anode and cathode chambers, can effectively conduct hydroxide ions while blocking hydrogen and oxygen, thereby ensuring efficient, safe, and stable operation of the device at high current densities, producing high-purity hydrogen with low energy consumption.

[0057] Example 1 An organic-inorganic composite membrane slurry, comprising a solid phase component and a liquid phase component, has the following formulation based on the total mass of the slurry: LDH nanosheets (nickel-iron hydrotalcite), with a mass fraction of 59% (of which 10% are 10-30 nm thick and 50-200 nm transverse, and 90% are 30-100 nm thick and 200-2000 nm transverse). Adhesive (polysulfone): 10% by mass; Pore-forming agent (polyvinylpyrrolidone): 1% by mass; Liquid phase component (N-methylpyrrolidone): 30% by mass.

[0058] This embodiment also specifically provides a method for preparing a slurry for organic-inorganic composite membranes, including the following steps: Weigh the required amount of binder powder and add it to the corresponding mass of the liquid phase component. Stir mechanically (300 rpm) for approximately 1 hour until completely dissolved, yielding a transparent, viscous solution. Add the weighed pore-forming agent to the above solution and continue stirring for approximately 30 minutes until completely dissolved. While continuing stirring, slowly add the pre-dried LDH nanosheets to the polymer solution. After all nanosheets have been added, continue stirring for 3 hours until the slurry is homogeneous, fine, and free of visible particles or agglomerates, obtaining the final slurry.

[0059] Example 2 An organic-inorganic composite membrane slurry, comprising a solid phase component and a liquid phase component, has the following formulation based on the total mass of the slurry: LDH nanosheets (zinc-aluminum hydrotalcite), with a mass fraction of 40% (of which 30% are 10-30 nm thick and 50-200 nm transverse, and 70% are 30-100 nm thick and 200-2000 nm transverse). Adhesive (polyethersulfone): 20% by mass; Pore-forming agent (polyvinylpyrrolidone): 5% by mass; Liquid phase component (N,N-dimethylacetamide): 35% by mass.

[0060] Preparation method: Refer to Example 1.

[0061] Example 3 An organic-inorganic composite membrane slurry, comprising a solid phase component and a liquid phase component, has the following formulation based on the total mass of the slurry: LDH nanosheets (magnesium aluminum hydrotalcite), with a mass fraction of 60% (of which 20% are 10~30 nm thick and 50~200 nm transverse, and 80% are 30~100 nm thick and 200~2000 nm transverse).

[0062] Adhesive (polysulfone): 10% by mass Pore-forming agent (polyethylene glycol): 2% by mass Liquid phase component (N,N-dimethylformamide): 28% by mass.

[0063] Preparation method: Refer to Example 1.

[0064] Example 4 An organic-inorganic composite membrane slurry, comprising a solid phase component and a liquid phase component, has the following formulation based on the total mass of the slurry: LDH nanosheets (nickel-iron hydrotalcite), 50% by mass (of which 15% are 10-30 nm thick and 50-200 nm transverse, and 85% are 30-100 nm thick and 200-2000 nm transverse). Adhesive (polyacrylonitrile): 16% by mass; Pore-forming agent (polyvinylpyrrolidone): 4% by mass; Liquid phase component (dimethyl sulfoxide): 30% by mass.

[0065] Preparation method: Refer to Example 1.

[0066] Example 5 An organic-inorganic composite membrane slurry, comprising a solid phase component and a liquid phase component, has the following formulation based on the total mass of the slurry: LDH nanosheets (calcium aluminum hydrotalcite), with a mass fraction of 48% (of which 25% are 10~30 nm thick and 50~200 nm transverse, and 75% are 30~100 nm thick and 200~2000 nm transverse). Binder (chitosan): 18% by mass; Pore-forming agent (polyethylene glycol): 2% by mass; Liquid phase component (N,N-dimethylacetamide): 32% by mass.

[0067] Preparation method: Refer to Example 1.

[0068] Example 6 An organic-inorganic composite membrane slurry, comprising a solid phase component and a liquid phase component, has the following formulation based on the total mass of the slurry: LDH nanosheets (nickel-iron hydrotalcite), with a mass fraction of 44% (of which 12% are 10-30 nm thick and 50-200 nm transverse, and 88% are 30-100 nm thick and 200-2000 nm transverse). Adhesive (polysulfone): 19% by mass; Pore-forming agent (polyethylene oxide-polypropylene oxide block copolymer): 3% by mass; Liquid phase component (N-methylpyrrolidone): 34% by mass.

[0069] Preparation method: Refer to Example 1.

[0070] Example 7 An organic-inorganic composite membrane slurry, comprising a solid phase component and a liquid phase component, has the following formulation based on the total mass of the slurry: LDH nanosheets (nickel-iron hydrotalcite), 44% by mass (with a thickness of 10-30 nm and a lateral dimension of 50-200 nm); Adhesive (polysulfone): 19% by mass; Pore-forming agent (polyethylene oxide-polypropylene oxide block copolymer): 3% by mass; Liquid phase component (N-methylpyrrolidone): 34% by mass.

[0071] Preparation method: Refer to Example 1.

[0072] Comparative Example 1 An organic-inorganic composite membrane slurry, comprising a solid phase component and a liquid phase component, has the following formulation based on the total mass of the slurry: LDH nanosheets (nickel-iron hydrotalcite), 44% by mass (with a thickness of 5-10 nm and a lateral dimension of 20-50 nm); Adhesive (polysulfone): 19% by mass; Pore-forming agent (polyethylene oxide-polypropylene oxide block copolymer): 3% by mass; Liquid phase component (N-methylpyrrolidone): 34% by mass.

[0073] Preparation method: Refer to Example 1.

[0074] Comparative Example 2 An organic-inorganic composite membrane, specifically the commercially available ZIRFON membrane (Agfa). Result detection The slurries obtained in each embodiment were used to prepare diaphragms. A cross-sectional view of the organic-inorganic composite diaphragm in Example 1 is shown below. Figure 1 As shown in Table 1, the performance of the membrane was compared with that of the commercially available ZIRFON membrane (Comparative Example 2).

[0075] The method for preparing the slurry into a diaphragm is as follows: (1) First, stir the slurry components thoroughly for 3 hours, then immerse the support completely in the casting liquid, and then use a scraping device with a double-sided scraper to control the distance between the support and the scraper to about 250 μm to prepare a wet composite membrane. (2) The above-mentioned wet composite membrane is placed in a phase inversion solution for phase inversion. The phase inversion temperature is 20°C, the phase inversion solution is a mixed solution of water and NMP, and the phase inversion time is 1 hour to ensure a relatively thorough phase inversion. During this process, the organic polymer resin in the casting solution solidifies, the solvent dissolves in the water, and the polymer resin and solvent undergo phase separation, becoming a solid resin and forming a porous structure. (3) After the phase transformation process is completed, boil the membrane in boiling water for 10 minutes to remove the residual solvent inside the membrane, and then store it in deionized water.

[0076] Performance testing includes tests such as surface resistivity and bubble point, and the specific methods are as follows: The method for testing surface resistivity is as follows: The diaphragm was cut into small pieces, soaked in a 30wt% KOH solution for one day, and then its resistance was tested using an electrochemical workstation.

[0077] The method for testing bubble point is as follows: The membrane was cut into small pieces, wetted with high-purity water, and tested using a bubble pressure membrane pore size analyzer (BSD-PB). A gas pressure was applied to one side of the membrane; the pressure at which a gas flow rate of 1 mL / min was detected on the other side was considered the bubble point of the membrane. The formula for calculating the bubble point is as follows: In the formula, D = pore diameter, unit μm; γ = surface tension of the liquid, unit: dny / cm; θ = contact angle, unit: degree; ΔP = pressure difference, unit: kPa.

[0078] A higher bubble point value indicates a stronger gas barrier property of the diaphragm.

[0079] The method for testing tensile strength is as follows: Cut small rectangular pieces of the diaphragm and place them on a tensile testing machine for testing.

[0080] The test method for insulation performance is as follows: Take a 5cm wide square diaphragm, clamp it between two stainless steel plates, and test its resistance using an electrochemical workstation.

[0081] Table 1 Test Project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 <![CDATA[Sheet resistance Ω / sq 2 > 0.11 0.12 0.14 0.11 0.15 0.16 0.19 0.28 0.35 Bubble Bar 18 19 18 22 21 18 17 12 3.2 Tensile strength (MPa) 61 63 60 59 58 61 56 52 55 Insulation performance Non-conductive Non-conductive Non-conductive Non-conductive Non-conductive Non-conductive Non-conductive Non-conductive Non-conductive As can be seen from the data in Table 1 above, the organic-inorganic composite membrane slurries of Examples 1-7 of the present invention exhibit good sheet resistance reduction effects when applied to membranes, with sheet resistance values ​​significantly lower than those of commercial membranes. The bubble point values ​​of the organic-inorganic composite membrane slurries of Examples 1-7 are also significantly higher than those of commercial ZIRFON membranes, indicating that the present invention significantly improves the gas barrier properties of the membrane. Furthermore, Table 1 also shows that the organic-inorganic composite membrane slurries of the present invention, when applied to membranes, can significantly improve their tensile strength and exhibit good mechanical stability, thus improving the long-term operational stability of the membrane.

[0082] In summary, it can be seen that the organic-inorganic composite diaphragm slurry of the present invention can not only reduce the sheet resistance of the diaphragm, but also achieve the synergistic improvement effect of gas barrier properties and long-term operational stability, which can fully meet the application requirements of alkaline water electrolysis diaphragms.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A slurry for an organic-inorganic composite diaphragm, comprising a solid phase component and a liquid phase component, characterized in that, The solid phase component includes LDH nanosheets, a binder, and a pore-forming agent; The LDH nanosheets account for 40-60% of the mass of the slurry; The LDH nanosheets have a thickness h of 10~100 nm and an average lateral dimension D of 50~2000 nm.

2. The slurry for organic-inorganic composite diaphragms according to claim 1, characterized in that, The thickness h of the LDH nanosheets and the average lateral dimension D satisfy the following condition: 2≤D / h≤40.

3. The slurry for organic-inorganic composite diaphragms according to claim 1 or 2, characterized in that, The LDH nanosheets have a thickness h of 10~30 nm and an average lateral dimension D of 50~200 nm.

4. The slurry for organic-inorganic composite membranes according to claim 1 or 2, characterized in that, The LDH nanosheets are composed of a mixture of two types of LDH nanosheets with different lateral dimensions. The average lateral dimension D1 of the small-sized LDH nanosheets and the average lateral dimension D2 of the large-sized LDH nanosheets satisfy the condition: D2 / D1>4. Preferably, the mass ratio of the small-sized LDH nanosheets to the large-sized LDH nanosheets is 1~3:

10.

5. The slurry for organic-inorganic composite membranes according to any one of claims 1 to 4, characterized in that, The mass ratio of the liquid phase component to the LDH nanosheets is 0.5~0.9:

1.

6. The slurry for organic-inorganic composite diaphragms according to any one of claims 1 to 5, characterized in that, At least one of the following characteristics must be met: a. The LDH nanosheets are selected from at least one of magnesium aluminum hydrotalcite, zinc aluminum hydrotalcite, nickel iron hydrotalcite, and calcium aluminum hydrotalcite; b. The binder is selected from at least one of polysulfone, polyethersulfone, polyarylsulfone, polyacrylonitrile, and chitosan, and preferably the binder accounts for 10-20% of the mass of the slurry; c. The pore-forming agent is selected from at least one of polyvinylpyrrolidone, polyethylene glycol, and polyethylene oxide-polypropylene oxide block copolymer, and preferably the pore-forming agent accounts for 1-5% of the mass of the slurry; d. The liquid phase component is selected from at least one of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide.

7. A method for preparing the slurry for an organic-inorganic composite diaphragm as described in any one of claims 1 to 6, characterized in that, Includes the following steps: The binder and pore-forming agent are added to the liquid phase component and stirred to dissolve. Then, LDH nanosheets are added and stirred for 2-5 hours to obtain the organic-inorganic composite membrane slurry.

8. An organic-inorganic composite membrane, characterized in that, It is prepared by a non-solvent-induced phase separation method, wherein the casting solution used is the organic-inorganic composite membrane slurry as described in any one of claims 1 to 6.

9. The organic-inorganic composite membrane according to claim 8, characterized in that, The organic-inorganic composite membrane has one of the following specific characteristics: a. The sheet resistivity of the organic-inorganic composite membrane is 0.1~0.2 Ωcm. 2 ; b. The bubble point pressure of the organic-inorganic composite diaphragm is 15~25 bar; c. The tensile strength of the organic-inorganic composite diaphragm is 58~65MPa.

10. An alkaline water electrolysis device, characterized in that, Includes the organic-inorganic composite membrane as described in claim 8 or 9.

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