Anion exchange composite membrane and preparation method and equipment thereof

Abstract

The invention provides an anion exchange composite membrane and a preparation method and equipment thereof, the anion exchange composite membrane comprises a first membrane layer, screen cloth and a second membrane layer which are stacked in sequence, both the first membrane layer and the second membrane layer comprise anion exchange polymers, and the aperture ratio of the screen cloth is 50%-70%. The mesh cloth is introduced as the reinforcing layer, so that the composite membrane can still keep excellent mechanical performance and dimensional stability in a working condition application state, the composite membrane can have good mechanical performance and ionic conduction performance by controlling the aperture ratio of the mesh cloth, and meanwhile, through the first membrane layer and the second membrane layer on the two sides of the mesh cloth, the ionic conduction performance of the composite membrane is improved. And the composite film has good gas barrier property.

Description

Technical Field

[0001] The present invention relates to the technical field of ion membranes, and in particular to an anion exchange composite membrane and a preparation method and equipment thereof. Background Art

[0002] Anion exchange membrane (AEM) is a special ion exchange membrane whose main function is to selectively transport anions in a liquid environment. This membrane is usually made of polymer materials and has fixed anion exchange sites that can exchange with anions in the liquid phase. Anion exchange membranes are mainly used in water electrolysis, fuel cells, CO2 reduction, water treatment and other application fields. This requires that the anion exchange membrane must have satisfactory mechanical properties, dimensional stability and chemical stability to meet long-term use, and also needs to have high ion conductivity to ensure high efficiency and low energy consumption in doing work. However, due to factors such as hydration in the working conditions, the mechanical properties of the AEM membrane of the homogeneous membrane system in the related art will be greatly attenuated, and it cannot meet long-term application requirements.

[0003] In response to this, researchers have prepared composite membranes through chemical cross-linking, inorganic nanoparticle doping, and setting up reinforced structures. However, while pursuing high mechanical properties, this either results in a decrease in gas barrier properties or a decrease in ion conductivity, making it difficult to effectively balance high ion conductivity with good gas barrier properties and mechanical properties. Summary of the Invention

[0004] The embodiments of the present invention provide an anion exchange composite membrane and a preparation method and device thereof, which can solve the technical problem that existing composite membranes are difficult to effectively achieve both high ion conductivity and good gas barrier properties and mechanical properties.

[0005] In a first aspect, an embodiment of the present invention provides an anion exchange composite membrane comprising a first membrane layer, a mesh, and a second membrane layer stacked in sequence, wherein both the first membrane layer and the second membrane layer comprise anion exchange polymers, and the mesh has an opening rate of 50% to 70%.

[0006] In one embodiment, the anion exchange polymer comprises one of a polyarylpiperidine polymer, a polyarylenepiperidine polymer, a polyarylquinine polymer, and a polybenzopyrazole polymer; and / or

[0007] The anion exchange polymer in the first membrane layer and the second membrane layer is of the same type; and / or

[0008] The material of the mesh includes one or more of polyetheretherketone, polyphenylene sulfide, polyethylene, polyethylene terephthalate, polypropylene and polytetrafluoroethylene.

[0009] In one embodiment, the thickness of the first film layer is 10 μm to 40 μm; and / or

[0010] The thickness of the mesh is 20 μm to 80 μm; and / or

[0011] The thickness of the second film layer is 10 μm to 40 μm; and / or

[0012] The mesh is formed by interweaving a plurality of warps and a plurality of wefts, wherein the distance between two adjacent warps is 100 μm to 200 μm, and the distance between two adjacent wefts is 100 μm to 200 μm.

[0013] In one embodiment, the degradation temperature of the mesh is ≥ 120°C; and / or

[0014] The contact angle of the mesh with pure water is ≤150°; and / or

[0015] The anion exchange polymer has an ion exchange capacity of 1.8 mmol / g to 4.0 mmol / g; and / or

[0016] The degradation temperature of anion exchange polymer is ≥120℃.

[0017] In the second aspect, an embodiment of the present invention provides a method for preparing an anion exchange composite membrane, comprising the following steps: providing a membrane layer slurry and a mesh, arranging the membrane layer slurry on both sides of the mesh to form a first membrane layer and a second membrane layer to obtain an anion exchange composite membrane, wherein the membrane layer slurry includes an anion exchange polymer, and the porosity of the mesh is 50% to 70%.

[0018] In one embodiment, the solid content of the membrane slurry is 15% wt to 25% wt; and / or

[0019] The viscosity of the membrane slurry is 5000 MPa.s@25℃~48000 MPa.s@25℃.

[0020] In one embodiment, the mesh is soaked in an alcohol solvent.

[0021] In one embodiment, the soaking time is 6 hours to 24 hours; and / or

[0022] The alcohol solvent includes one or more of methanol, ethanol, and isopropanol.

[0023] In one embodiment, a film slurry is placed on both sides of a mesh to form a first film layer and a second film layer, comprising:

[0024] providing a substrate, and disposing the film layer slurry on the substrate to obtain a first wet film layer;

[0025] Laminating one surface of the mesh to a side of the first wet film layer facing away from the substrate to obtain a first composite body, wherein the first composite body includes the mesh and the first wet film layer;

[0026] The first composite body attached to the surface of the substrate is subjected to a first drying treatment, and the film slurry is then provided on the other side of the mesh to form a second wet film layer, and then a second drying treatment is performed to form a first film layer and a second film layer.

[0027] In one embodiment, the first drying temperature is 40° C. to 60° C., and the first drying time is 5 min to 50 min; and / or

[0028] The second drying includes drying at 40°C to 60°C for 1 hour to 2 hours, drying at 70°C to 90°C for 2 hours to 3 hours, and drying at 60°C to 80°C for 1 hour to 2 hours.

[0029] In a third aspect, an embodiment of the present invention provides a device comprising the above-mentioned anion exchange composite membrane, or an anion exchange composite membrane prepared by the above-mentioned method for preparing anion exchange composite membrane.

[0030] In an embodiment of the present invention, by introducing a mesh as a reinforcement layer, the anion exchange composite membrane can still maintain good mechanical properties and dimensional stability under working application conditions (referring to the use process of the anion exchange composite membrane). By controlling the porosity of the mesh, the composite membrane can have good mechanical properties and ion conductivity properties. At the same time, through the first membrane layer and the second membrane layer on both sides of the mesh, the composite membrane can have good gas barrier properties. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0032] The technical solution of this application is as follows:

[0033] In the first aspect, an embodiment of the present application provides an anion exchange composite membrane, comprising a first membrane layer, a mesh, and a second membrane layer stacked in sequence, wherein the first membrane layer and the second membrane layer both comprise anion exchange polymers, and the mesh has an opening rate of 50% to 70%, for example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc.

[0034] In this application, the mesh is introduced as a reinforcement layer, allowing the composite membrane to maintain good mechanical properties and dimensional stability under operating conditions. Controlling the mesh's porosity allows the composite membrane to have good mechanical properties and ion conductivity. Furthermore, the first and second membrane layers on both sides of the mesh provide the composite membrane with good gas barrier properties. The porosity is the percentage of the mesh's pore area to its total area.

[0035] In some embodiments, the anion exchange polymer in the first and second membrane layers is the same type. Using the same anion exchange polymer in the first and second membrane layers can enhance the coupling effect between the first and second membrane layers, reduce the interfacial separation between the two layers, and thus improve the mechanical properties of the composite membrane.

[0036] In some embodiments, the anion exchange polymer includes one of a polyarylpiperidine polymer, a polyarylenepiperidine polymer, a polyarylquinine polymer, and a polybenzopyrazole polymer. This can provide the composite membrane with a low surface resistance, thereby improving the electrochemical performance of the composite membrane and simultaneously enhancing the gas barrier properties of the composite membrane.

[0037] In some embodiments, the thickness of the first film layer is 10μm to 40μm, for example, it can be 10μm, 12μm, 15μm, 17μm, 20μm, 22μm, 25μm, 27μm, 30μm, 32μm, 35μm, 37μm, 40μm, etc. In this way, it can effectively block gas, regulate ion conductivity and provide mechanical properties.

[0038] In some embodiments, the thickness of the second film layer is 10μm to 40μm, for example, it can be 10μm, 12μm, 15μm, 17μm, 20μm, 22μm, 25μm, 27μm, 30μm, 32μm, 35μm, 37μm, 40μm, etc., so that it can effectively block gas, regulate ion conductivity and provide mechanical properties.

[0039] In some embodiments, the anion exchange polymer has an ion exchange capacity (IEC) of 1.8 mmol / g to 4.0 mmol / g, for example, 1.8 mmol / g, 2.0 mmol / g, 2.2 mmol / g, 2.4 mmol / g, 2.6 mmol / g, 2.8 mmol / g, 3.0 mmol / g, 3.2 mmol / g, 3.4 mmol / g, 3.6 mmol / g, 3.8 mmol / g, 4.0 mmol / g, etc. This allows the composite to have high ionic conductivity.

[0040] In some embodiments, the degradation temperature of the anion exchange polymer is ≥120° C. In this way, the application scenarios of the composite membrane material can be expanded and the composite membrane material can have good stability during application.

[0041] In some embodiments, the mesh material includes one or more of polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), and polytetrafluoroethylene (PTFE). As such, the mesh is less susceptible to hydration and can effectively maintain mechanical properties in alkaline environments, thereby enabling the composite membrane to maintain excellent mechanical properties and dimensional stability even in working conditions.

[0042] In the present application, polytetrafluoroethylene (PTFE) includes expanded polytetrafluoroethylene (ePTFE).

[0043] In some embodiments, the mesh has a thickness of 20 μm to 80 μm, for example, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, etc. In this way, the composite membrane can have good mechanical properties and ion conductivity.

[0044] In some embodiments, the mesh is interwoven with a plurality of warp threads and a plurality of weft threads. The distance between adjacent warp threads is 100 μm to 200 μm, for example, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, etc., and the distance between adjacent weft threads is 100 μm to 200 μm, for example, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, etc. This can improve the mechanical properties of the composite membrane. The distance between warp threads and the porosity work together to give the composite membrane good mechanical properties and ion conductivity.

[0045] In some embodiments, the degradation temperature of the mesh is ≥120° C. In this way, the application scenarios of the composite film material can be expanded and the composite film material can have good stability during application.

[0046] In some embodiments, the mesh has a contact angle of ≤150° with pure water. This can improve the electrochemical performance of the composite membrane. The mesh has a certain degree of hydrophilicity, which can enhance the hydrophilicity of the composite membrane. When the composite membrane is used in an aqueous environment, the better the overall hydrophilicity of the composite membrane, the better the electrochemical performance of the composite membrane.

[0047] In a second aspect, the present invention provides a method for preparing an anion exchange composite membrane, comprising the following steps:

[0048] A membrane layer slurry and a mesh are provided, and the membrane layer slurry is arranged on both sides of the mesh to form a first membrane layer and a second membrane layer to obtain an anion exchange composite membrane. The membrane layer slurry includes an anion exchange polymer.

[0049] In some embodiments, the method for preparing the membrane slurry comprises the following steps:

[0050] An anion exchange polymer and a solvent are provided, mixed and heated, and then filtered and centrifuged for degassing to obtain a membrane layer slurry.

[0051] In some embodiments, the heating temperature is 60° C. to 100° C., for example, 60° C., 70° C., 80° C., 90° C., 100° C., etc., and the heating time is 1 hour to 6 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, etc. In this way, the anion exchange polymer can be fully dissolved in the solvent.

[0052] In some embodiments, the solids content of the membrane slurry is 15% to 25% by weight. This allows the membrane slurry to effectively form a film on the mesh and control the film thickness. The solids content of the membrane slurry affects the viscosity of the membrane slurry, thereby ensuring good film-forming properties.

[0053] In some embodiments, the viscosity of the membrane slurry is 5000 MPa.s@25℃ to 48000 MPa.s@25℃, for example, it can be 5000 MPa.s@25℃, 10000 MPa.s@25℃, 15000 MPa.s@25℃, 20000 MPa.s@25℃, 25000 MPa.s@25℃, 30000 MPa.s@25℃, 35000 MPa.s@25℃, 40000 MPa.s@25℃, 45000 MPa.s@25℃, 48000 MPa.s@25℃, etc.

[0054] In some embodiments, the solvent includes one or more of dimethyl sulfoxide, N-methyl-2-pyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0055] In some embodiments, the mesh is soaked in an alcohol solvent. Alcohol solvents are polar and volatile. This prevents the alcohol solvent from remaining in the mesh, improves the free energy of the mesh surface, and enhances the wetting and filling effect of the anion exchange polymer on the mesh. This further enhances the composite effect between the mesh and the membrane layer, improves the gas barrier properties of the composite membrane, and reduces the presence of oily impurities.

[0056] In some embodiments, the soaking treatment time is 6 hours to 24 hours, for example, it can be 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, etc.

[0057] In some embodiments, the alcohol solvent includes one or more of methanol, ethanol, and isopropanol.

[0058] In some embodiments, a film slurry is disposed on both sides of a mesh to form a first film layer and a second film layer, comprising:

[0059] providing a substrate, and disposing the film layer slurry on the substrate to obtain a first wet film layer;

[0060] Laminating one surface of the mesh to a side of the first wet film layer facing away from the substrate to obtain a first composite body, wherein the first composite body includes the mesh and the first wet film layer;

[0061] The first composite body attached to the surface of the substrate is subjected to a first drying treatment, and the film slurry is then provided on the other side of the mesh to form a second wet film layer, and then a second drying treatment is performed to form a first film layer and a second film layer.

[0062] In the present application, the membrane slurry is disposed on a substrate, and the membrane slurry can be disposed on the substrate by blade coating. The membrane slurry is disposed on the other side surface of the mesh to form a second wet film layer, and the second wet film layer can be formed by coating the membrane slurry on the other side surface of the mesh. Since the mesh is a porous material, by disposing the membrane slurry on a substrate and then laminating it with the mesh to form a first wet film layer disposed on one side surface of the mesh, the bonding effect between the mesh and the membrane slurry can be improved, and the probability of the slurry dripping from the mesh pores can be reduced compared to coating the slurry directly on the mesh. The substrate can be made of PET polyester film, and the substrate is removed after the anion exchange composite membrane is prepared.

[0063] In some embodiments, the first drying temperature is 40°C to 60°C, for example, it can be 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, etc., and the first drying time is 5min to 50min, for example, it can be 5min, 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, etc.

[0064] In some embodiments, the secondary drying step includes drying at 40°C to 60°C for 1 to 2 hours, 70°C to 90°C for 2 to 3 hours, and finally 60°C to 80°C for 1 to 2 hours. This ensures a good film formation. Excessively high initial drying temperatures can cause the film surface to dry too quickly, resulting in an orange peel effect.

[0065] In a third aspect, an embodiment of the present application provides a device comprising the above-mentioned anion exchange composite membrane.

[0066] The equipment provided in this application includes water electrolysis hydrogen production equipment, alkaline fuel cells, water treatment equipment, and CO2 reduction equipment.

[0067] The following describes the method in conjunction with specific embodiments.

[0068] Example 1

[0069] An anion exchange composite membrane and a preparation method thereof, comprising the following steps:

[0070] (1) An aryl compound and a carbonyl compound are subjected to a hydroxyalkylation reaction under super acid catalysis, and after the reaction, the aryl compound and the carbonyl compound are mixed with dimethyl sulfoxide. After the mixture is mixed, a quaternary ammonium agent is added, and the mixture is stirred and heated to 70° C. for 24 hours to obtain a polyarylpiperidine polymer resin (with an ion exchange capacity (IEC) of 1.8 mmol / g to 4.0 mmol / g);

[0071] (2) Weighing 15 g of polyarylpiperidine polymer resin, blending it with 65 g of dimethyl sulfoxide, dissolving it at 80° C., filtering it, and degassing it by centrifugation to obtain a membrane slurry with a solid content of 16 wt% and a viscosity of 8100 MPa.s @ 25° C.;

[0072] (3) Soak the PEEK mesh in ethanol at room temperature for 24 hours and then remove it for use;

[0073] (4) The membrane slurry was scraped onto a flat PET substrate to obtain a coating with a thickness of 60 μm. A 40 μm thick PEEK mesh (porosity of 60%) was then spread on the coating surface, and then dried at 50°C for 30 min. Then, a coating with a thickness of 80 μm was applied to the surface of the PEEK mesh. The membrane was then dried at 60°C for 2 h, 80°C for 3 h, and 70°C for 1 h to obtain an ion exchange composite membrane with a thickness of 100 μm (the mesh was 40 μm thick, and the thickness of the two membrane layers on both sides of the mesh was 30 μm).

[0074] Example 2

[0075] This embodiment is substantially the same as embodiment 1, except that in this embodiment, the polyaryl piperidine polymer resin is replaced with a polyarylene piperidine polymer resin, and the viscosity of the membrane slurry is 8200 MPa.s@25°C.

[0076] Example 3

[0077] This embodiment is basically the same as Example 1, except that in this embodiment, the polyarylpiperidine polymer resin is replaced with a polyarylquinine polymer resin, the amount of dimethyl sulfoxide used is 70 g, the solid content of the membrane layer slurry is 15 wt%, and the viscosity of the membrane layer slurry is 6400 MPa.s@25°C.

[0078] Example 4

[0079] This embodiment is basically the same as Example 1, except that in this embodiment, the polyarylpiperidine polymer resin is replaced with a polyarylquinine polymer resin, the solid content of the membrane slurry is 17 wt %, and the viscosity of the membrane slurry is 9300 MPa.s@25°C.

[0080] Example 5

[0081] This embodiment is basically the same as embodiment 1, with the only difference being that the mesh in this embodiment is 80 μm thick.

[0082] Example 6

[0083] This embodiment is basically the same as embodiment 1, with the only difference being that the mesh in this embodiment is 20 μm thick.

[0084] Example 7

[0085] This embodiment is substantially the same as the embodiment 1, with the only difference being that the thicknesses of the two film layers on both sides of the mesh in this embodiment are 10 μm and 50 μm, respectively.

[0086] Example 8

[0087] This embodiment is substantially the same as the embodiment 1, with the only difference being that the thicknesses of the two film layers on both sides of the mesh in this embodiment are 20 μm and 40 μm, respectively.

[0088] Example 9

[0089] This embodiment is basically the same as the embodiment 1, with the only difference being that the opening rate of the mesh in this embodiment is 50%.

[0090] Example 10

[0091] This embodiment is basically the same as the embodiment 1, with the only difference being that the opening rate of the mesh in this embodiment is 70%.

[0092] Example 11

[0093] This embodiment is substantially the same as embodiment 1, with the only difference being that the solid content of the membrane slurry in this embodiment is 15.1 wt % and the viscosity is 5000 MPa.s@25°C.

[0094] Example 12

[0095] This embodiment is substantially the same as embodiment 1, with the only difference being that the solid content of the membrane slurry in this embodiment is 24.0 wt % and the viscosity is 48,000 MPa.s@25° C.

[0096] Example 13

[0097] This embodiment is substantially the same as the embodiment 1, with the only difference being that the thickness of the two film layers on both sides of the mesh in this embodiment is both 40 μm.

[0098] Example 14

[0099] This embodiment is substantially the same as embodiment 1, with the only difference being that the solid content of the membrane slurry in this embodiment is 25.7 wt % and the viscosity is 55,000 MPa.s@25° C.

[0100] Example 15

[0101] This embodiment is basically the same as embodiment 1, except that step (3) in this embodiment is:

[0102] A 40 μm thick PEEK mesh was immersed in the membrane slurry. After the membrane slurry adhered to the mesh, it was taken out and dried at 60°C for 2h, 80°C for 3h, and 70°C for 1h to obtain an ion exchange composite membrane with a thickness of 100 μm.

[0103] Comparative Example 1

[0104] This comparative example is basically the same as Example 1, except that step (3) in this comparative example is: the membrane slurry is scraped onto a flat PET substrate with a coating thickness of 160 μm, and then dried at 60°C for 2 h, 80°C for 3 h, and 70°C for 1 h to obtain an ion exchange homogeneous membrane with a thickness of 100 μm.

[0105] Comparative Example 2

[0106] This comparative example is basically the same as Example 6, except that step (3) in this comparative example is:

[0107] The membrane slurry was coated on a PET substrate with a 20 μm PEEK mesh to a coating thickness of 160 μm, and then dried at 60°C for 2 h, 80°C for 3 h, and 70°C for 1 h to obtain an ion exchange composite membrane with a thickness of 80 μm.

[0108] Comparative Example 3

[0109] This embodiment is basically the same as the embodiment 1, with the only difference being that the opening rate of the mesh in this embodiment is 90%.

[0110] Test Example: The anion exchange composite membranes obtained in the examples and comparative examples were subjected to performance tests, and the test data are shown in Table 1.

[0111] 1. Mechanical properties test

[0112] Test method: Refer to GB / T 1447-2005 Test method for tensile properties of fiber reinforced plastics

[0113] Measure the thickness and width of anion exchange composite membranes under constant temperature and humidity conditions of 23°C ± 2°C and 50% ± 10%. Place the anion exchange composite membrane in a test fixture. Determine the tensile strength and elongation at break using various tensile speeds within the range of 50 mm / min to 200 mm / min. Each tensile speed should be applied to a separate anion exchange composite membrane. After the anion exchange composite membrane breaks, read the corresponding load value.

[0114] a. Tensile strength: The ratio of the maximum load that an anion exchange composite membrane can withstand when breaking under pure tensile force to the width of the stretched membrane material. It is divided into transverse and longitudinal tensile strengths and is used to evaluate the mechanical strength of the membrane.

[0115] b. Elongation at break: The ratio of the distance between two points at break to the original length under the maximum load applied to the anion exchange composite membrane before rupture. This is the maximum deformation an alkaline membrane can withstand before breaking, and is used to indicate the membrane's flexibility.

[0116] 2. Swelling performance test

[0117] Test method: Cut the anion exchange composite membrane into 2cm*4cm size, put it into 1M KOH solution, change the alkali three times, and conduct swelling performance test in 80℃ deionized water.

[0118] 3. Electrolyzed water application test

[0119] The anion exchange composite membrane was made into a membrane electrode with an active area of 80 cm 2 , cathode nickel-molybdenum alloy loading is 1.0 mg / cm 2 , the anode nickel ferrite loading is 1.2 mg / cm 2 , and then assembled into a single-cell electrolyzer. Under the operating temperature of 60°C, the positive and negative electrodes were connected, and the polarization performance and surface resistance of the composite membrane were tested using an electrochemical workstation.

[0120] a. Polarization performance: Use the electrochemical workstation to select the linear voltammetry (LSV) test mode, and the current test range is generally 0-80V (based on 80cm 2 The test obtains information such as potential and current curve, and further information processing is used to obtain polarization performance.

[0121] b. Sheet resistance: Use an electrochemical workstation in the electrochemical impedance spectroscopy (EIS) mode to obtain high-frequency impedance information. This information is then processed to determine the sheet resistance.

[0122] Table 1

[0123]

[0124] Note: In Example 15, the membrane material produced by the single immersion process had pits on the membrane surface; in Comparative Example 2, the composite homogeneous layer and the mesh were separated during the short-term test process.

[0125] From Table 1 we can see that:

[0126] Compared with Examples 1 to 4, the test results of anion exchange composite membranes made of different anion exchange polymers are similar, which means that the preparation process of the present application has universal applicability and can respond to the composite requirements of different anion exchange polymers.

[0127] Comparing Examples 1, 5, and 6, with varying mesh thicknesses, increasing mesh thickness leads to higher tensile strength and lower swelling ratios for the corresponding composite membranes, but also higher sheet resistance and higher polarization performance. This suggests that thicker meshes improve mechanical properties but worsen electrochemical performance.

[0128] Comparing Examples 1, 7, and 8, the test results for the anion exchange composite membranes were similar under the same composite membrane thickness conditions, indicating that fluctuations in the thickness of the first and second membrane layers had no significant effect on material properties. Comparing Examples 1, 7, and 8 with Example 13, Example 13 exhibited higher tensile strength, higher elongation at break, and lower swelling ratio, but also higher sheet resistance and higher polarization performance. This indicates that different composite membrane thicknesses significantly affect mechanical and electrochemical properties: thicker membranes exhibit better mechanical properties, but worse electrochemical performance.

[0129] Compared with Examples 1, 9, and 10 and Comparative Example 3, the mechanical and electrochemical properties of Examples 1, 9, and 10 are similar, the tensile strength and elongation at break of Example 14 are significantly lower than those of Examples 1, 9, and 10, the swelling ratio of Comparative Example 3 is significantly higher than those of Examples 1, 9, and 10, and the surface resistance and polarization properties of Comparative Example 3 are slightly lower than those of Examples 1, 9, and 10. It can be seen that at the same composite film thickness, an open porosity of 50% to 70% has no significant effect on the electrochemical properties, but has a weak effect on the mechanical properties. When the open porosity is 90%, the electrochemical properties are slightly improved, but the mechanical properties of the membrane are significantly reduced.

[0130] Compared with Examples 1, 11, 12, and 14, the surface resistance and polarization performance of Example 14 are significantly increased compared with Examples 1, 11, and 12. The reason is that the excessively high viscosity makes the infiltration and composite effect of the anion exchange polymer poor, and there may be more voids in the composite membrane, which increases the mass transfer resistance and ultimately leads to the deterioration of the electrochemical performance of the composite membrane.

[0131] Compared with Examples 1 and 15, the surface resistance and polarization performance of the composite membrane prepared by the one-time immersion process of Example 1 are higher than those of the composite membrane prepared by the two-time coating process of Example 1, and there are pits on the membrane surface of the composite membrane prepared by the one-time immersion process, which is caused by the loss of slurry in the mesh pores during the drying stage, and the thickness uniformity of the composite membrane is poor.

[0132] Compared with Example 1 and Comparative Example 1, under the conditions of the same anion exchange polymer and the same anion exchange composite membrane thickness, the tensile strength of Example 1 is much greater than that of Comparative Example 1, that is, the anion exchange composite membrane in Example 1 exhibits more excellent mechanical properties; the swelling rate of Example 1 is much smaller than that of Comparative Example 1, which means that the anion exchange composite membrane of Example 1 has excellent dimensional stability and can overcome the deformation problem in the working application stage; the surface resistance and polarization properties of Example 1 and Comparative Example 1 are similar, indicating that the composite membrane under the process of the present application can still maintain electrochemical properties equivalent to the homogeneous membrane in Comparative Example 1.

[0133] Compared with Example 6 and Comparative Example 2, the mechanical properties are similar under the two composite processes, but Example 6 shows better dimensional stability (lower swelling rate), which is mainly attributed to the difference in the restraining effect of the reinforcing layer (mesh) on the homogeneous layer (membrane layer). An overly thick homogeneous layer weakens the restraining effect of the reinforcing layer, making it impossible to effectively control the swelling of the composite film. In addition, in Comparative Example 2, the homogeneous layer and the mesh separate during the short-term test process. A homogeneous layer that is too thick on one side will aggravate the separation of the two phases.

[0134] The embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. An anion exchange composite membrane, characterized in that The invention comprises a first membrane layer, a mesh and a second membrane layer which are stacked in sequence. The first membrane layer and the second membrane layer both comprise anion exchange polymers. The mesh has an opening rate of 50% to 70%.

2. The anion exchange composite membrane according to claim 1, characterized in that The anion exchange polymer comprises one of a polyarylpiperidine polymer, a polyarylenepiperidine polymer, a polyarylquinine polymer, and a polybenzopyrazole polymer; and / or The anion exchange polymer in the first membrane layer and the second membrane layer are of the same type; and / or The material of the mesh includes one or more of polyetheretherketone, polyphenylene sulfide, polyethylene, polyethylene terephthalate, polypropylene and polytetrafluoroethylene.

3. The anion exchange composite membrane according to claim 1, characterized in that The thickness of the first film layer is 10 μm to 40 μm; and / or The thickness of the second film layer is 10 μm to 40 μm; and / or The mesh has a thickness of 20 μm to 80 μm; and / or The mesh is formed by interweaving a plurality of warps and a plurality of wefts, wherein the distance between two adjacent warps is 100 μm to 200 μm, and the distance between two adjacent wefts is 100 μm to 200 μm.

4. The anion exchange composite membrane according to claim 1, characterized in that The degradation temperature of the mesh is ≥120°C; and / or The contact angle of the mesh to pure water is ≤150°; and / or The anion exchange polymer has an ion exchange capacity of 1.8 mmol / g to 4.0 mmol / g; and / or The degradation temperature of the anion exchange polymer is ≥120°C.

5. A method for preparing an anion exchange composite membrane, characterized in that: The following steps are involved: A membrane layer slurry and a mesh are provided, and the membrane layer slurry is arranged on both sides of the mesh to form a first membrane layer and a second membrane layer to obtain an anion exchange composite membrane. The membrane layer slurry includes an anion exchange polymer, and the mesh has an opening rate of 50% to 70%.

6. The method for preparing an anion exchange composite membrane according to claim 5, characterized in that: The solid content of the membrane slurry is 15% wt to 25% wt; and / or The viscosity of the membrane layer slurry is 5000 MPa.s@25°C to 48000 MPa.s@25°C.

7. The method for preparing an anion exchange composite membrane according to claim 5, characterized in that: The mesh is obtained by soaking in an alcohol solvent.

8. The method for preparing an anion exchange composite membrane according to claim 7, characterized in that: The soaking treatment time is 6h to 24h; and / or The alcohol solvent includes one or more of methanol, ethanol, and isopropanol.

9. The method for preparing an anion exchange composite membrane according to claim 5, characterized in that: The method of placing the film slurry on both sides of the mesh to form a first film layer and a second film layer includes: providing a substrate, and disposing the film layer slurry on the substrate to obtain a first wet film layer; Laminating one surface of the mesh to a side of the first wet film layer facing away from the substrate to obtain a first composite body, wherein the first composite body includes the mesh and the first wet film layer; The first composite body attached to the surface of the substrate is subjected to a first drying treatment, and the film slurry is then provided on the other side of the mesh to form a second wet film layer, and then a second drying treatment is performed to form a first film layer and a second film layer.

10. The method for preparing an anion exchange composite membrane according to claim 9, characterized in that: The first drying temperature is 40° C. to 60° C., and the first drying time is 5 min to 50 min; and / or The second drying comprises drying at 40° C. to 60° C. for 1 hour to 2 hours, drying at 70° C. to 90° C. for 2 hours to 3 hours, and drying at 60° C. to 80° C. for 1 hour to 2 hours.

11. A device, characterized in that The invention comprises the anion exchange composite membrane according to any one of claims 1 to 4, or the anion exchange composite membrane prepared by the preparation method of the anion exchange composite membrane according to any one of claims 5 to 10.

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