Hydrophilic slurries and their use, composite separators and methods of making and using the same

Abstract

The application relates to the technical field of hydrogen production by electrolysis of water, and discloses a hydrophilic slurry and application thereof, a composite diaphragm and a preparation method and application thereof. The hydrophilic slurry contains a high-molecular polymer, Ti-O-Zr composite oxide, a toughening agent and an organic solvent; wherein, based on the total weight of the hydrophilic slurry, the content of the high-molecular polymer is 10-20 wt%, the content of the Ti-O-Zr composite oxide is 30-50 wt%, the content of the toughening agent is 1-5 wt%, and the content of the organic solvent is 35-50 wt%. The hydrophilic slurry provided by the application has strong hydrophilicity; when a polymer coating formed by the hydrophilic slurry is applied to a composite diaphragm, the wettability of the material can be improved on one hand, and the hydrophilicity of the composite diaphragm can be effectively improved on the other hand; the surface resistance of the composite diaphragm can be effectively reduced; the electrolysis efficiency of hydrogen production by alkaline electrolysis of water can be improved; and the electrolysis energy consumption can be greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production technology, specifically to hydrophilic slurries and their applications, composite membranes and their preparation methods and applications. Background Technology

[0002] Alkaline water electrolysis technology is mature and more suitable for large-scale green electricity hydrogen production scenarios. Currently, the core development of alkaline water electrolysis hydrogen production systems is towards greater efficiency. Among these, the diaphragm is a key component affecting the current density, energy consumption, and safety of the water electrolysis hydrogen production system, and it is necessary to minimize the surface resistivity while ensuring airtightness.

[0003] Currently, the mainstream membrane used in the market is made of polyphenylene sulfide (PPS) mesh, but its poor hydrophilicity prevents the electrolyte from fully penetrating the membrane pores, leading to increased membrane resistance. Foreign manufacturer AGFA has coated the PPS woven mesh with a slurry containing ZrO2 and polysulfone, improving the hydrophilicity of the membrane, but its sheet resistance and stability still need optimization. For example, CN113862821A discloses a method for preparing a polyphenylene sulfide (PPS) fiber fabric type alkaline water electrolysis membrane. This technical solution involves mixing PPS resin with zirconia inorganic nanoparticles, granulating the mixture, drying it, and then melt-spinning it to obtain zirconia-modified PPS fibers. These zirconia-modified PPS fibers are then spun into yarn to obtain the final PPS fabric type alkaline water electrolysis membrane. This membrane does not have the problems of coating debonding and powder shedding. However, there is a situation where the zirconia inorganic nanoparticles are encapsulated in the resin matrix by the PPS resin, which leads to a decrease in the hydrophilicity of the membrane, an increase in the surface resistivity, and a reduction in electrolysis efficiency. At the same time, it increases the energy consumption for water electrolysis.

[0004] CN117512693A discloses a composite membrane for alkaline water electrolysis hydrogen production with a superhydrophilic surface and an integral cross-linked structure. The composite membrane consists of a polymeric film-forming agent, nano-sized cellulose or its derivatives, and hydrophilic inorganic nanoparticles. The hydrophilic inorganic nanoparticles are one or more combinations of zirconium dioxide, cerium dioxide, titanium dioxide, aluminum oxide, barium sulfate, and magnesium hydroxide. The polymeric film-forming agent is one or more combinations of polysulfone, polyethersulfone, polyphenylsulfone, polypropylene, polyphenylene sulfide, poly(p-phenylenebenzobisoxazole), polyketone, polyimide, polyetherimide, polyphenylene copolymer, and polyetheretherketone. However, this patented technology requires first coating the support with a hydrophilic polymer to obtain a modified porous support, then preparing a casting solution to coat and phase-invert the modified porous support to form a film, followed by another hydrophilic polymer coating and partial thermal cross-linking and post-treatment. Therefore, this technology is relatively complex, has a long process flow, and is difficult to industrialize.

[0005] In response to this, there is an urgent need to develop a membrane for alkaline water electrolysis hydrogen production that possesses high hydrophilicity, low surface resistivity, and high stability. Summary of the Invention

[0006] The purpose of this invention is to provide a diaphragm for alkaline water electrolysis hydrogen production with high hydrophilicity, low surface resistivity and high stability, thereby improving the efficiency of water electrolysis hydrogen production and reducing energy consumption.

[0007] To achieve the above objectives, a first aspect of the present invention provides a hydrophilic slurry containing a high molecular weight polymer, a Ti-O-Zr composite oxide, a toughening agent, and an organic solvent.

[0008] Based on the total weight of the hydrophilic slurry, the content of the polymer is 10-20 wt%, the content of the Ti-O-Zr composite oxide is 30-50 wt%, the content of the toughening agent is 1-5 wt%, and the content of the organic solvent is 35-50 wt%.

[0009] The weight-average molecular weight of the polymer is 50,000 to 300,000.

[0010] The average pore size of the Ti-O-Zr composite oxide is 1-10 nm;

[0011] In the Ti-O-Zr composite oxide, the molar ratio of titanium to zirconium is 1:0.4-2.5.

[0012] A second aspect of the invention provides the use of the hydrophilic slurry described in the first aspect in a diaphragm.

[0013] A third aspect of the present invention provides a composite membrane comprising a support layer and a polymer coating coated on both sides of the support layer; the polymer coating is formed from the hydrophilic slurry described in the first aspect.

[0014] A fourth aspect of the present invention provides a method for preparing the composite membrane described in the third aspect, the method comprising:

[0015] (1) A hydrophilic slurry is coated on both sides of the surface of the support layer to obtain an intermediate;

[0016] (2) The intermediate is placed in water and / or ethanol for curing treatment to obtain the composite membrane;

[0017] The hydrophilic slurry is the hydrophilic slurry described in the first aspect.

[0018] The fifth aspect of the present invention provides the application of the composite membrane described in the third aspect in alkaline water electrolysis for hydrogen production.

[0019] Through the above technical solution, the present invention has at least the following advantages:

[0020] The hydrophilic slurry provided by this invention has strong hydrophilicity. When the polymer coating formed by this hydrophilic slurry is applied to a composite membrane, it can adsorb and store water molecules, improving the wettability of the material; on the other hand, it can effectively improve the hydrophilicity and OH conductivity of the composite membrane. - This capability effectively reduces the surface resistance of the composite membrane, improves the electrolysis efficiency of alkaline water electrolysis for hydrogen production, and significantly reduces electrolysis energy consumption. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] As mentioned above, a first aspect of the present invention provides a hydrophilic slurry containing a high molecular weight polymer, a Ti-O-Zr composite oxide, a toughening agent, and an organic solvent;

[0023] Based on the total weight of the hydrophilic slurry, the content of the polymer is 10-20 wt%, the content of the Ti-O-Zr composite oxide is 30-50 wt%, the content of the toughening agent is 1-5 wt%, and the content of the organic solvent is 35-50 wt%.

[0024] The weight-average molecular weight of the polymer is 50,000 to 300,000.

[0025] The average pore size of the Ti-O-Zr composite oxide is 1-10 nm;

[0026] In the Ti-O-Zr composite oxide, the molar ratio of titanium to zirconium is 1:0.4-2.5.

[0027] Preferably, the average particle diameter of the Ti-O-Zr composite oxide is 10-50 nm, more preferably 30-50 nm. The inventors discovered in their research that, under this preferred condition, the technical solution of the present invention can obtain a composite membrane with stronger hydrophilicity, lower sheet resistance, and higher stability. This composite membrane can further improve the efficiency of hydrogen production through water electrolysis and reduce energy consumption.

[0028] Preferably, the weight-average molecular weight of the polymer is 50,000 to 200,000.

[0029] Preferably, the specific surface area of ​​the Ti-O-Zr composite oxide is 80-120 m². 2 / g, pore volume 0.1-0.5cm 3 / g.

[0030] More preferably, the specific surface area of ​​the Ti-O-Zr composite oxide is 100-120 m². 2 / g, pore volume 0.2-0.3cm 3 / g. The inventors discovered in their research that, under this preferred condition, the technical solution of the present invention can further improve the hydrophilicity and stability of the composite membrane, while reducing its sheet resistance, improving the efficiency of hydrogen production through water electrolysis, and reducing energy consumption.

[0031] In a preferred embodiment, the polymer is selected from at least one of polysulfone, polyethersulfone, polyphenylsulfone, and polyetheretherketone.

[0032] According to another preferred embodiment, the polymer is a combination of polyphenylsulfone and polysulfone, with a mass ratio of 1:0.5-1.5.

[0033] Preferably, the toughening agent is selected from at least one of dimethyl phthalate, dibutyl phthalate, and dioctyl phthalate.

[0034] In a preferred embodiment, the organic solvent is selected from at least one of N-methylpyrrolidone, N-ethylpyrrolidone, dimethyl sulfoxide, dimethylacetamide, and N'N-dimethylformamide.

[0035] The present invention does not impose any particular limitation on the preparation method of the Ti-O-Zr composite oxide. Those skilled in the art can choose from the known technical means in the art, as long as the Ti-O-Zr composite oxide that meets the requirements of the present invention can be prepared. However, in order to obtain a composite membrane product with higher hydrophilicity and stability and lower sheet resistance, the present invention preferably uses the following two methods to prepare the Ti-O-Zr composite oxide.

[0036] According to a preferred embodiment, the Ti-O-Zr composite oxide is prepared by a method comprising the following steps:

[0037] S1: In the presence of an alkaline substance, a precursor solution I containing ZrOCl2 and TiCl4 is subjected to a coprecipitation reaction to obtain a precipitate; the amount of alkaline substance used is such that the initial pH value of the coprecipitation reaction system is 8-10.

[0038] S2: The precipitate is calcined to obtain the Ti-O-Zr composite oxide.

[0039] Preferably, in step S1, the alkaline substance is ammonia water, and more preferably, the concentration of the ammonia water is 25-28 wt%.

[0040] More preferably, in step S1, the alkaline substance is introduced into the coprecipitation reaction system by dropwise addition.

[0041] Preferably, in step S1, the conditions for the coprecipitation reaction include: a temperature of 20-30°C and a time of 10-12 hours.

[0042] The coprecipitation reaction time described in this invention is started from the end of the dropwise addition, excluding the dropwise addition time.

[0043] In a preferred embodiment, in step S1, the sum of the concentrations of ZrOCl2 and TiCl4 in the precursor solution I is 0.8-1.2 mol / L.

[0044] According to a particularly preferred embodiment, in step S2, the method further includes: first washing and drying the precipitate sequentially, then calcining the dried product I, and grinding and sieving the calcined product II to obtain the Ti-O-Zr composite oxide.

[0045] Preferably, in step S2, the conditions for calcination I include: a temperature of 300-800℃ and a time of 2-4h.

[0046] According to another preferred embodiment, the Ti-O-Zr composite oxide is prepared by the following method:

[0047] The precursor solution II containing zirconium n-butoxide and tetrabutyl titanate was sequentially acidified and calcined.

[0048] Preferably, the solvent in the precursor solution II is ethanol and / or n-butanol.

[0049] In a preferred embodiment, the sum of the concentrations of zirconium n-butoxide and tetrabutyl titanate in the precursor solution II is 0.5-1 mol / L.

[0050] Preferably, the acidification is carried out using a dilute acid with a hydrogen ion concentration of 0.001-0.1 mol / L, wherein the dilute acid is selected from at least one of dilute hydrochloric acid, dilute nitric acid and dilute sulfuric acid.

[0051] In a preferred embodiment, the acidification conditions include a temperature of 20-30°C and a time of 10-12 hours.

[0052] Preferably, the conditions for calcination II include: a temperature of 300-800℃ and a time of 2-4 hours.

[0053] Preferably, the preparation method of the Ti-O-Zr composite oxide further includes: grinding and sieving the product obtained by calcination II to obtain the Ti-O-Zr composite oxide.

[0054] It should be noted that the loss of titanium and zirconium elements during the preparation process of the Ti-O-Zr composite oxide is negligible in this invention.

[0055] As previously stated, a second aspect of the present invention provides the application of the hydrophilic slurry described in the first aspect in a diaphragm.

[0056] As previously described, a third aspect of the present invention provides a composite membrane comprising a support layer and a polymer coating coated on both sides of the support layer; the polymer coating is formed from the hydrophilic slurry described in the first aspect.

[0057] Preferably, the composite membrane has a surface porosity of 50-68% and an average pore size of 95-120 nm.

[0058] Preferably, the contact angle of the composite diaphragm is 60-69°.

[0059] Preferably, the sheet resistivity of the composite diaphragm is 0.15-0.28 Ω·m. 2 Its bubble point at 20°C is 3.5-5.0 bar.

[0060] As previously described, a fourth aspect of the present invention provides a method for preparing the composite membrane described in the third aspect, the method comprising:

[0061] (1) A hydrophilic slurry is coated on both sides of the surface of the support layer to obtain an intermediate;

[0062] (2) The intermediate is placed in water and / or ethanol for curing treatment to obtain the composite membrane;

[0063] The hydrophilic slurry is the hydrophilic slurry described in the first aspect.

[0064] Preferably, before step (1), the polymer, Ti-O-Zr composite oxide, toughening agent and organic solvent are mixed to form a hydrophilic slurry.

[0065] The present invention does not impose any particular limitation on the mixing method, as long as the materials in the hydrophilic slurry are mixed evenly; for example, a vacuum heating stirrer or a planetary gravity disperser can be used to mix the hydrophilic slurry.

[0066] Preferably, the temperature of the mixing conditions is 70-90°C.

[0067] In a preferred embodiment, in step (1), the thickness of each of the two coatings is independently 0.2-0.3 mm / side.

[0068] Preferably, in step (1), the support layer is selected from at least one type of mesh material, wherein the mesh material has an average pore size of 350-400 μm, an average thickness of 100-300 μm, and a porosity of 30-70%.

[0069] More preferably, the material of the mesh fabric is selected from at least one of polyphenylene sulfide, polypropylene, polyetheretherketone and polyamide.

[0070] According to another preferred embodiment, the mesh material is made of polyphenylene sulfide and polypropylene.

[0071] More preferably, the weight-average molecular weight of the mesh material is 10,000-500,000, and more preferably 50,000-300,000.

[0072] Preferably, in step (2), the curing conditions include: a time of 30-60 min and a temperature of 20-30 °C.

[0073] In a preferred embodiment, the method in step (2) further includes: after obtaining the intermediate in step (1), placing the intermediate in water and / or ethanol for the curing treatment within 5-20 seconds. The inventors have discovered in their research that, in this preferred embodiment, the technical solution of the present invention can obtain a composite membrane with more suitable pore size and porosity. This composite membrane has higher hydrophilicity and stability, and lower sheet resistance, which can further improve the efficiency of hydrogen production through water electrolysis and reduce energy consumption.

[0074] As previously stated, the fifth aspect of the present invention provides the application of the composite membrane described in the third aspect in alkaline water electrolysis for hydrogen production.

[0075] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, the compounds and reagents used are all commercially available products.

[0076] Polysulfone: weight average molecular weight of 80,000.

[0077] Polyethersulfone: weight average molecular weight is 80,000.

[0078] Support layer-1: The material is a mesh fabric of polyphenylene sulfide with a weight average molecular weight of 50,000; it is made of polyphenylene sulfide raw material purchased from Toray Industries, Inc. and woven by a weaving machine; the average pore size is 380μm, the average thickness is 256μm, and the porosity is 53%.

[0079] Support layer-2: The material is a polypropylene mesh with a weight-average molecular weight of 300,000; it is made of polypropylene raw materials purchased from Beijing Yanshan Petrochemical Co., Ltd. and woven by a weaving machine; the average pore size is 380μm, the average thickness is 260μm, and the porosity is 50%.

[0080] Support layer-3: The material is a mesh fabric formed by the composite of polyphenylene sulfide with a weight average molecular weight of 50,000 and polypropylene with a weight average molecular weight of 300,000; the polyphenylene sulfide raw materials are purchased from Toray Industries, Inc. and the polypropylene raw materials are purchased from Beijing Yanshan Petrochemical Co., Ltd., and woven by a weaving machine; the average pore size is 350μm, the average thickness is 260μm, and the porosity is 50%.

[0081] Preparation Example 1: Preparation of Ti-O-Zr composite oxides

[0082] (1) In the presence of an alkaline substance (ammonia water, 28wt%), a precursor solution containing ZrOCl2 and TiCl4 with a total concentration of 1mol / L was subjected to a coprecipitation reaction to obtain a precipitate;

[0083] (2) The precipitate was washed and dried in sequence, and the dried product I was calcined. The calcined product I was then ground and sieved to obtain Ti-O-Zr composite oxide.

[0084] The methods used in the examples of this invention for preparing Ti-O-Zr composite oxides are the same, except that the raw material ratios and process parameters are different, resulting in Ti-O-Zr composite oxides with different characteristic parameters. The raw material ratios and process parameters of the Ti-O-Zr composite oxides are listed in Table 1. The parts not listed are the same as those in preparation example 1.

[0085] Table 1

[0086]

[0087] Example 1: Preparation of composite membrane

[0088] (1) First, use a mixer (vacuum heating stirrer) to mix the polymer, Ti-O-Zr composite oxide, toughening agent (dimethyl phthalate) and organic solvent (N-methylpyrrolidone) (temperature 80℃, time 30min) and then let it stand to degas, forming a hydrophilic slurry;

[0089] (2) Add the hydrophilic slurry into the material tank of the double-sided coating machine and coat it on both sides of the support layer to obtain the intermediate;

[0090] (3) Within 20 seconds, the intermediate is placed in water for solidification to obtain a composite membrane.

[0091] For specific materials and reaction conditions in this embodiment, please refer to Table 2.

[0092] The remaining embodiments were prepared using the same method as in Example 1, except that the materials and reaction conditions were different, as shown in Table 2.

[0093] Table 2 (each 1 wt% represents 1 g)

[0094]

[0095] Example 4

[0096] Following a method similar to that of Example 1, except that the Ti-O-Zr composite oxide F1 in Example 1 was replaced with an equal mass of F4, while all other aspects remained the same, a composite membrane was obtained.

[0097] Example 5

[0098] Following a method similar to that of Example 1, except that the Ti-O-Zr composite oxide F1 in Example 1 was replaced with an equal mass of F5, while all other aspects remained the same, a composite membrane was obtained.

[0099] Comparative Example 1

[0100] Following a method similar to that of Example 1, except that the Ti-O-Zr composite oxide F1 in Example 1 was replaced with an equal mass of DF1, while all other aspects remained the same, a composite membrane was obtained.

[0101] Comparative Example 2

[0102] Following a method similar to that of Example 1, except that the Ti-O-Zr composite oxide F1 in Example 1 was replaced with an equal mass of DF2, while all other aspects remained the same, a composite membrane was obtained.

[0103] Comparative Example 3

[0104] The method is similar to that in Example 1, except that the material composition is different. Specifically, the material composition is as follows:

[0105] Based on the total weight of the hydrophilic slurry, the content of the polymer is 30wt%, the content of the Ti-O-Zr composite oxide is 20wt%, the content of the toughening agent is 1wt%, and the content of the organic solvent is 49wt%.

[0106] A composite diaphragm was obtained.

[0107] Comparative Example 4

[0108] Following a method similar to that of Example 1, except that the Ti-O-Zr composite oxide F1 in Example 1 was replaced with an equal mass of commercially available ZrO2 with an average particle diameter of 30 nm, while all other aspects remained the same, a composite membrane was obtained.

[0109] Comparative Example 5

[0110] Following a method similar to that of Example 1, except that the Ti-O-Zr composite oxide F1 in Example 1 was replaced with an equal mass of commercially available TiO2 with an average particle diameter of 30 nm, while all other aspects remained the same, a composite membrane was obtained.

[0111] Test Example 1

[0112] The composite membranes prepared in the examples were subjected to pore size, contact angle and surface resistivity tests, including surface porosity, average pore size, contact angle, surface resistivity and bubble point. The test results are shown in Table 3.

[0113] The testing methods involved are as follows:

[0114] (1) The porosity of the composite membrane was measured using a weighing method. First, the composite membrane sample was cut into 10mm × 10mm pieces and thoroughly wetted with deionized water. Then, the surface moisture was quickly and gently wiped away with filter paper, and the mass of the wet composite membrane was accurately weighed using an analytical balance. Next, the membrane was vacuum dried at 60℃ for at least 3 hours, and the mass of the dry composite membrane was weighed again. The porosity of the composite membrane was calculated.

[0115] (2) The average pore size and bubble point of the composite membrane were tested using the bubble point method. The composite membrane sample was immersed in water at 20°C, and pressurized gas with gradually increasing pressure was introduced until the gas passed through the membrane and the pressure at which the first bubble appeared was taken as the bubble point. The maximum pore size and average pore size of the composite membrane were calculated using the formula.

[0116] (3) The contact angle of the composite membrane was measured by the lying drop method in the experiment. During the test, the composite membrane sample was placed flat on the sample stage, and 2 μL of water was dropped onto the membrane surface with a graduated syringe. The baseline position was adjusted, and the data was recorded after 15 seconds.

[0117] (4) The sheet resistance of the composite membrane was determined by electrochemical impedance spectroscopy. The composite membrane was immersed in a 30 wt% potassium hydroxide solution at 30 °C. The resistance value was measured when the area was 10 mm × 10 mm. The resistance value of the same concentration potassium hydroxide solution was also measured when the area was the same. The difference between the two resistance values ​​was obtained. The product of the difference and the tested area of ​​the membrane was the resistance of the membrane.

[0118] Table 3

[0119]

[0120]

[0121] The results above show that the composite membranes prepared in Examples 1-5 have small average pore size, high surface porosity, and higher safety and stability. Simultaneously, these composite membranes exhibit small contact angles, good hydrophilicity, low surface resistivity, and high bubble points. This demonstrates that the hydrophilic slurry provided by this invention has superior overall performance. When applied to composite membranes, it can improve the electrolysis efficiency of alkaline water electrolysis for hydrogen production and significantly reduce electrolysis energy consumption.

[0122] Application examples

[0123] The composite membranes prepared above were subjected to water electrolysis operation tests to test the relationship between current density and voltage. The test conditions are shown in Table 4, and the test results are shown in Table 5.

[0124] Table 4

[0125] project parameter cathode catalyst Platinum-plated titanium felt Anode catalyst Pure nickel mesh (40 mesh, Chinese standard) Flow field area 5cm×5cm electrolyte 30wt% KOH Electrolyte flow rate 600mL / min Activation treatment <![CDATA[30min@100mA·cm -2 ]]>

[0126] Table 5

[0127]

[0128]

[0129] Table 5 (continued)

[0130]

[0131] As can be seen from the results in Table 5, the hydrophilic slurry provided by the present invention has strong hydrophilicity. The composite membrane prepared by the polymer coating formed by the hydrophilic slurry and applied to the alkaline water electrolysis hydrogen production process has a smaller voltage at the same current density, resulting in higher electrolysis efficiency and lower energy consumption.

[0132] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A hydrophilic slurry, characterized in that, This hydrophilic slurry contains high molecular weight polymers, Ti-O-Zr composite oxides, toughening agents, and organic solvents; Based on the total weight of the hydrophilic slurry, the content of the polymer is 10-20 wt%, the content of the Ti-O-Zr composite oxide is 30-50 wt%, the content of the toughening agent is 1-5 wt%, and the content of the organic solvent is 35-50 wt%. The weight-average molecular weight of the polymer is 50,000 to 300,000. The average pore size of the Ti-O-Zr composite oxide is 1-10 nm; In the Ti-O-Zr composite oxide, the molar ratio of titanium to zirconium is 1:0.4-2.

5.

2. The hydrophilic slurry according to claim 1, wherein, The average particle diameter of the Ti-O-Zr composite oxide is 10-50 nm.

3. The hydrophilic slurry according to claim 1 or 2, wherein, The specific surface area of ​​the Ti-O-Zr composite oxide is 80-120 m². 2 / g, pore volume 0.1-0.5cm 3 / g.

4. The hydrophilic slurry according to any one of claims 1-3, wherein, The polymer is selected from at least one of polysulfone, polyethersulfone, polyphenylsulfone, and polyetheretherketone; And / or, the toughening agent is selected from at least one of dimethyl phthalate, dibutyl phthalate and dioctyl phthalate; And / or, the organic solvent is selected from at least one of N-methylpyrrolidone, N-ethylpyrrolidone, dimethyl sulfoxide, dimethylacetamide, and N'N-dimethylformamide.

5. The application of the hydrophilic slurry according to any one of claims 1-4 in a diaphragm.

6. A composite diaphragm, characterized in that, The composite membrane includes a support layer and a polymer coating applied to both sides of the support layer surface; The polymer coating is formed from the hydrophilic slurry according to any one of claims 1-4.

7. A method for preparing the composite diaphragm according to claim 6, characterized in that, The method includes: (1) A hydrophilic slurry is coated on both sides of the surface of the support layer to obtain an intermediate; (2) The intermediate is placed in water and / or ethanol for curing treatment to obtain the composite membrane; Wherein, the hydrophilic slurry is the hydrophilic slurry according to any one of claims 1-4.

8. The method according to claim 7, wherein, In step (1), the thickness of each double-sided coating is independently 0.2-0.3 mm / side; And / or, in step (2), the curing conditions include: a time of 30-60 min and a temperature of 20-30 °C.

9. The method according to claim 7 or 8, wherein, The method in step (2) further includes: placing the intermediate in water and / or ethanol for the curing treatment within 5-20 seconds.

10. The method according to any one of claims 7-9, wherein, In step (1), the support layer is selected from at least one of the mesh fabric materials, wherein the average pore size of the mesh fabric material is 350-400 μm, the average thickness is 100-300 μm, and the porosity is 30-70%.

11. The method according to claim 10, wherein, The material of the mesh fabric is selected from at least one of polyphenylene sulfide, polypropylene, polyetheretherketone, and polyamide; Preferably, the weight-average molecular weight of the mesh material is between 10,000 and 500,000.

12. The application of the composite membrane according to claim 6 in alkaline water electrolysis for hydrogen production.

Images