Anion exchange composite membrane and preparation method therefor, and apparatus

Abstract

The present application relates to the technical field of ion exchange membranes, and provides an anion exchange composite membrane and a preparation method therefor, and an apparatus. The anion exchange composite membrane comprises a first membrane layer, a mesh fabric, and a second membrane layer which are sequentially stacked, wherein each of the first membrane layer and the second membrane layer comprises an anion exchange polymer, and the mesh fabric has an open area ratio of 50%-70%.

Description

Anion exchange composite membrane, its preparation method and equipment

[0001] This application claims priority to Chinese Patent Application No. 2025103633201, filed on March 25, 2025, entitled "Anion Exchange Composite Membrane and Preparation Method and Equipment Thereof", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of ion exchange membrane technology, and in particular to an anion exchange composite membrane, its preparation method, and equipment. Background Technology

[0003] Anion exchange membranes (AEMs) are a special type of ion exchange membrane whose primary function is to selectively transport anions in a liquid environment. These membranes are typically made of polymer materials and have 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, and water treatment. This requires anion exchange membranes to possess satisfactory mechanical properties, dimensional stability, and chemical stability to meet long-term use requirements, as well as high ionic conductivity to ensure high efficiency and low energy consumption. However, the mechanical properties of homogeneous AEM membrane systems in related technologies degrade significantly due to factors such as hydration under operating conditions, making them unsuitable for long-term applications. Invention Overview

[0004] To address this, researchers have prepared composite films through chemical cross-linking, inorganic nanoparticle doping, and the creation of reinforcing structures. However, in pursuing high mechanical properties, either the gas barrier properties or the ion conductivity are reduced, making it difficult to effectively balance high ion conductivity with good gas barrier and mechanical properties.

[0005] The embodiments of this application provide an anion exchange composite membrane, its preparation method, and equipment, which can improve the technical problem that existing composite membranes are difficult to effectively balance high ion conductivity with good gas barrier properties and mechanical properties.

[0006] In a first aspect, embodiments of this application provide an anion exchange composite membrane, comprising a first membrane layer, a mesh fabric, and a second membrane layer stacked sequentially, wherein both the first and second membrane layers comprise anion exchange polymers, and the mesh fabric has an open porosity of 50% to 70%.

[0007] In one embodiment, the anion exchange polymer includes one of polyarylpiperidine polymers, polyarylpiperidine polymers, polyarylquinine polymers, and polybenzopyrazole polymers; and / or

[0008] The anion exchange polymers in the first and second membrane layers are of the same type; and / or

[0009] The materials used for the mesh fabric include one or more of polyetheretherketone, polyphenylene sulfide, polyethylene, polyethylene terephthalate, polypropylene, and polytetrafluoroethylene.

[0010] In one embodiment, the thickness of the first film layer is 10 μm to 40 μm; and / or

[0011] The thickness of the mesh fabric is 20μm~80μm; and / or

[0012] The thickness of the second film layer is 10 μm to 40 μm; and / or

[0013] The mesh is made of multiple warp and weft threads interwoven together, with the distance between two adjacent warp threads being 100μm to 200μm and the distance between two adjacent weft threads being 100μm to 200μm.

[0014] In one embodiment, the degradation temperature of the mesh is ≥120°C; and / or

[0015] The contact angle of the mesh with pure water is ≤150°; and / or

[0016] The ion exchange capacity of the anion exchange polymer is 1.8 mmol / g to 4.0 mmol / g; and / or

[0017] The degradation temperature of anion exchange polymers is ≥120℃.

[0018] Secondly, embodiments of this application provide a method for preparing an anion exchange composite membrane, comprising the following steps: providing a membrane slurry and a mesh fabric, disposing the membrane slurry on both sides of the mesh fabric to form a first membrane layer and a second membrane layer, thereby obtaining an anion exchange composite membrane, wherein the membrane slurry comprises anion exchange polymer and the mesh fabric has an open porosity of 50% to 70%.

[0019] In one embodiment, the solid content of the membrane slurry is 15%wt to 25%wt; and / or

[0020] The viscosity of the membrane slurry is 5000 mPa.s@25℃ to 48000 mPa.s@25℃.

[0021] In one embodiment, the mesh fabric is obtained by soaking in an alcohol solvent.

[0022] In one embodiment, the soaking treatment time is 6h to 24h; and / or

[0023] Alcohol solvents include one or more of methanol, ethanol, and isopropanol.

[0024] In one embodiment, a film slurry is disposed on both sides of a mesh fabric to form a first film layer and a second film layer, comprising:

[0025] A substrate is provided, and the film slurry is disposed on the substrate to obtain a first wet film layer;

[0026] One side surface of the mesh fabric is bonded to the side of the first wet film layer opposite to the substrate to obtain a first composite, the first composite comprising the mesh fabric and the first wet film layer.

[0027] The first composite attached to the surface of the substrate is subjected to a first drying process, and then the film slurry is applied to the other side of the mesh to form a second wet film layer. Then, a second drying process is performed to form the first film layer and the second film layer.

[0028] In one embodiment, the temperature of the first drying is 40°C to 60°C, and the drying time is 5 min to 50 min; and / or

[0029] The second drying process includes drying at 40℃~60℃ for 1h~2h, at 70℃~90℃ for 2h~3h, and at 60℃~80℃ for 1h~2h in sequence.

[0030] Thirdly, embodiments of this application provide an apparatus comprising the anion exchange composite membrane described above, or an anion exchange composite membrane prepared by the method described above.

[0031] In the embodiments of this application, by introducing a mesh fabric as a reinforcing layer, the anion exchange composite membrane can maintain good mechanical properties and dimensional stability under operating conditions (referring to the use of the anion exchange composite membrane). By controlling the porosity of the mesh fabric, the composite membrane can have good mechanical properties and ion conduction properties. At the same time, through the first and second membrane layers on both sides of the mesh fabric, the composite membrane can have good gas barrier properties. Embodiments of the present invention

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention and are not intended to limit the present invention.

[0033] The technical solution of this application is as follows:

[0034] In a first aspect, embodiments of this application provide an anion exchange composite membrane, comprising a first membrane layer, a mesh fabric, and a second membrane layer stacked sequentially. Both the first and second membrane layers comprise anion exchange polymers. The mesh fabric has an open porosity of 50% to 70%, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc.

[0035] In this application, by introducing a mesh fabric as a reinforcing layer, the composite membrane can maintain good mechanical properties and dimensional stability under operating conditions. By controlling the porosity of the mesh fabric, the composite membrane can possess good mechanical properties and ion conductivity. Simultaneously, the first and second membrane layers on both sides of the mesh fabric enable the composite membrane to have good gas barrier properties. The porosity is the percentage of the pore area on the mesh fabric to the total area of ​​the mesh fabric.

[0036] In some embodiments, the anion exchange polymers in the first and second membrane layers are of the same type. Thus, using the same anion exchange polymer in both the first and second membrane layers can improve the coupling effect between them, reduce interfacial separation, and thereby enhance the mechanical properties of the composite membrane.

[0037] In some embodiments, the anion exchange polymer includes one of polyarylpiperidine polymers, polyarylpiperidine polymers, polyarylquinine polymers, and polybenzopyrazole polymers. This allows the composite membrane to have low surface resistance, thereby improving both its electrochemical performance and its gas barrier properties.

[0038] 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., so that it can effectively block gas, regulate ion conductivity and provide mechanical properties.

[0039] 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.

[0040] In some embodiments, the ion exchange capacity (IEC) of the anion exchange polymer is 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 possess high ion conductivity.

[0041] In some embodiments, the degradation temperature of the anion exchange polymer is ≥120°C. This expands the application scenarios of the composite membrane and ensures its good stability during industrial applications.

[0042] 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). Thus, the mesh exhibits a weak response to hydration and effectively maintains its mechanical properties in alkaline environments, enabling the composite membrane to maintain excellent mechanical properties and dimensional stability under operating conditions.

[0043] In this application, polytetrafluoroethylene (PTFE) includes expanded polytetrafluoroethylene (ePTFE).

[0044] In some embodiments, the thickness of the mesh fabric is 20 μm to 80 μm, for example, it can be 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. This allows the composite membrane to possess good mechanical and ion conductivity properties.

[0045] In some embodiments, the mesh fabric is composed of multiple warp and weft threads interwoven together. The distance between two adjacent warp threads is 100μm to 200μm, for example, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, etc. The distance between two adjacent weft threads is also 100μm to 200μm, for example, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, etc. This improves the mechanical properties of the composite membrane. The combined effect of the distance between the warp threads and the porosity gives the composite membrane good mechanical and ion conductivity properties.

[0046] In some embodiments, the degradation temperature of the mesh fabric is ≥120°C. This expands the application scenarios of the composite membrane material and ensures its good stability during application.

[0047] In some embodiments, the contact angle of the mesh fabric with pure water is ≤150°. Further, the contact angle of the mesh fabric with pure water is ≤90°. This improves the electrochemical performance of the composite membrane. The mesh fabric has a certain degree of hydrophilicity, which can enhance the hydrophilicity of the composite membrane. When used in an aqueous environment, the better the overall hydrophilicity of the composite membrane, the better its electrochemical performance.

[0048] Secondly, embodiments of this application provide a method for preparing anion exchange composite membrane, comprising the following steps:

[0049] A membrane slurry and a mesh are provided. The membrane slurry is placed on both sides of the mesh to form a first membrane layer and a second membrane layer, thereby obtaining an anion exchange composite membrane. The membrane slurry contains anion exchange polymer.

[0050] In some embodiments, the method for preparing the membrane slurry includes the following steps:

[0051] Anion exchange polymer and solvent are provided, mixed and heated, then filtered and centrifuged to remove bubbles, to obtain a membrane slurry.

[0052] In some embodiments, the anion exchange polymer may be at least one of polyarylpiperidine polymer resin, polyarylpiperidine polymer resin, and polyarylquinine polymer resin.

[0053] In some embodiments, the ion-exchange capacity (IEC) of the anion-exchange polymer is 1.6 mmol / g to 4.0 mmol / g. Further, the IEC of the anion-exchange polymer is 1.6 mmol / g to 3.5 mmol / g.

[0054] 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 1h to 6h, for example, 1h, 2h, 3h, 4h, 5h, 6h, etc. This allows the anion exchange polymer to be fully dissolved in the solvent.

[0055] In some embodiments, the solid content of the membrane slurry is 15%wt to 25%wt. This allows the membrane slurry to form an effective film on the mesh fabric, and the film thickness can be controlled. The solid content of the membrane slurry affects its viscosity, thereby enabling the membrane slurry to have good film-forming properties.

[0056] In some embodiments, the viscosity of the film 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.

[0057] In some embodiments, the solvent includes one or more of dimethyl sulfoxide, N-methyl-2-pyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0058] In some embodiments, the mesh fabric is obtained by soaking in an alcohol solvent. The alcohol solvent is a polar solvent and readily volatile. This prevents the alcohol solvent from remaining in the mesh fabric, improves the free energy of the mesh fabric surface, enhances the wetting and filling effect of the anion exchange polymer on the mesh fabric, thereby improving the composite effect of the mesh fabric and the membrane layer, enhancing the gas barrier properties of the composite membrane, and reducing potential oil and impurities.

[0059] In some embodiments, the soaking time is 6h to 24h, for example, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, etc.

[0060] In some embodiments, the alcohol solvent includes one or more of methanol, ethanol, and isopropanol.

[0061] In some embodiments, a film slurry is disposed on both sides of a mesh fabric to form a first film layer and a second film layer, including:

[0062] A substrate is provided, and the film slurry is disposed on the substrate to obtain a first wet film layer;

[0063] One side surface of the mesh fabric is bonded to the side of the first wet film layer opposite to the substrate to obtain a first composite, the first composite comprising the mesh fabric and the first wet film layer.

[0064] The first composite attached to the surface of the substrate is subjected to a first drying process, and then the film slurry is applied to the other side of the mesh to form a second wet film layer. Then, a second drying process is performed to form the first film layer and the second film layer.

[0065] In this application, the membrane slurry is placed on the substrate, which can be achieved by coating the membrane slurry onto the substrate. A second wet film layer is formed by applying the membrane slurry to the other side of the mesh fabric. Since the mesh fabric is a porous material, by placing the membrane slurry on the substrate and then bonding it to the mesh fabric to form the first wet film layer on one side of the mesh fabric, the bonding effect between the mesh fabric and the membrane slurry can be improved. Compared with directly coating the slurry onto the mesh fabric, the probability of slurry dripping from the mesh fabric pores can be reduced. The substrate can be a PET polyester film, which is removed after the anion exchange composite membrane is prepared.

[0066] In some embodiments, the temperature of the first drying 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 drying time is 5 min to 50 min, for example, it can be 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, etc.

[0067] In some embodiments, the second drying process includes drying at 40°C~60°C for 1-2 hours, at 70°C~90°C for 2-3 hours, and at 60°C~80°C for 1-2 hours sequentially. This ensures good film formation. Excessively high initial drying temperatures can lead to rapid drying of the film surface, resulting in an orange peel effect.

[0068] Thirdly, embodiments of this application provide an apparatus including the anion exchange composite membrane described above.

[0069] The equipment provided in this application includes water electrolysis hydrogen production equipment, alkaline fuel cells, water treatment equipment, and CO2 reduction equipment.

[0070] The following description is based on specific embodiments.

[0071] Example 1

[0072] An anion exchange composite membrane is prepared by the following steps:

[0073] (1) Triphenyl and N-methyl-4-piperidinone were subjected to hydroxyalkylation reaction under superacid catalysis at a molar ratio of 1:1. After the reaction was completed, they were mixed with dimethyl sulfoxide, and iodomethane was added after mixing. The mixture was stirred and heated to 70°C for 24 h to obtain polyarylpiperidine polymer resin (IEC 1.6 mmol / g~2.8 mmol / g).

[0074] (2) Weigh 15g of polyarylepiperidine polymer resin and mix it with 65g of dimethyl sulfoxide. Dissolve the mixture at 80°C, filter and centrifuge to remove bubbles, and obtain a film slurry with a solid content of 16wt% and a viscosity of 8100mPa.s@25°C.

[0075] (3) Soak the PEEK mesh in ethanol at room temperature for 24 hours, then remove and set aside for use;

[0076] (4) The membrane slurry is scraped onto a flat PET substrate to obtain a coating with a thickness of 60 μm. Then, a 40 μm thick PEEK mesh (with an opening rate of 60%) is laid flat on the coating surface and dried at 50°C for 30 min. Then, a coating with a thickness of 80 μm is coated on the PEEK mesh surface. Then, the mesh is dried at 60°C for 2 h, 80°C for 3 h, and 70°C for 1 h in sequence to obtain an ion exchange composite membrane with a thickness of 100 μm (the mesh is 40 μm thick and the thickness of the two membrane layers on both sides of the mesh is 30 μm).

[0077] Example 2

[0078] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the polyarylpiperidine polymer resin is replaced with polyarylpiperidine polymer resin, and the viscosity of the film slurry is 8200 mPa.s@25℃.

[0079] Example 3

[0080] This embodiment is basically the same as Embodiment 1, except that the polyarylpiperidine polymer resin is replaced with polyarylquinine polymer resin in this embodiment; wherein, the raw materials are p-terphenyl and 3-quinine cycloketone hydrochloride in a molar ratio of 1:1; the solid content of the membrane slurry is 15wt%, and the viscosity of the membrane slurry is 6400mPa.s@25℃.

[0081] Example 4

[0082] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the polyarylpiperidine polymer resin is replaced with polyarylquinine polymer resin, and the solid content of the film slurry is 17wt%, and the viscosity of the film slurry is 9300mPa.s@25℃.

[0083] Example 5

[0084] This embodiment is basically the same as Embodiment 1, except that the mesh thickness in this embodiment is 80μm.

[0085] Example 6

[0086] This embodiment is basically the same as embodiment 1, except that the mesh thickness in this embodiment is 20μm.

[0087] Example 7

[0088] This embodiment is basically the same as Embodiment 1, except that the thicknesses of the two film layers on both sides of the mesh in this embodiment are 10μm and 50μm, respectively.

[0089] Example 8

[0090] This embodiment is basically the same as Embodiment 1, except that the thicknesses of the two film layers on both sides of the mesh in this embodiment are 20μm and 40μm, respectively.

[0091] Example 9

[0092] This embodiment is basically the same as embodiment 1, except that the opening rate of the mesh in this embodiment is 50%.

[0093] Example 10

[0094] This embodiment is basically the same as embodiment 1, except that the opening rate of the mesh in this embodiment is 70%.

[0095] Example 11

[0096] This embodiment is basically the same as Embodiment 1, except that the solid content of the film slurry in this embodiment is 15.1wt% and the viscosity is 5000mPa.s@25℃.

[0097] Example 12

[0098] This embodiment is basically the same as Embodiment 1, except that the solid content of the film slurry in this embodiment is 24.0 wt% and the viscosity is 48000 mPa.s@25℃.

[0099] Example 13

[0100] This embodiment is basically the same as Embodiment 1, except that the thickness of the two film layers on both sides of the mesh in this embodiment is 40μm.

[0101] Example 14

[0102] This embodiment is basically the same as Embodiment 1, except that the solid content of the film slurry in this embodiment is 25.7wt% and the viscosity is 55000mPa.s@25℃.

[0103] Example 15

[0104] This embodiment is basically the same as embodiment 1, except that step (3) in this embodiment is:

[0105] A 40μm thick PEEK mesh was immersed in the membrane slurry. After the membrane slurry adhered to the mesh, it was taken out and dried sequentially at 60℃ for 2 hours, 80℃ for 3 hours, and 70℃ for 1 hour to obtain an ion exchange composite membrane with a thickness of 100μm.

[0106] Comparative Example 1

[0107] This comparative example is basically the same as Example 1, except that step (3) in this comparative example is:

[0108] The membrane slurry was coated onto a flat PET substrate with a coating thickness of 160 μm. It was then dried sequentially at 60℃ for 2 h, 80℃ for 3 h, and 70℃ for 1 h to obtain an ion exchange homogeneous membrane with a thickness of 100 μm.

[0109] Comparative Example 2

[0110] This comparative example is basically the same as Example 6, except that step (3) in this comparative example is:

[0111] The membrane slurry was coated onto a PET substrate with a 20μm PEEK mesh, resulting in a coating thickness of 160μm. The coating was then dried sequentially at 60℃ for 2 hours, 80℃ for 3 hours, and 70℃ for 1 hour to obtain an ion exchange composite membrane with a thickness of 80μm.

[0112] Comparative Example 3

[0113] This embodiment is basically the same as Embodiment 1, except that the opening rate of the mesh in this embodiment is 90%.

[0114] Test example: The performance of the anion exchange composite membranes obtained in the examples and comparative examples was tested, and the test data are shown in Table 1.

[0115] 1. Mechanical performance testing

[0116] Test Method: Refer to GB / T 1447-2005, Tensile Properties Test Method for Fiber Reinforced Plastics. Under constant temperature and humidity conditions of 23℃±2℃ and 50%±10%, measure the thickness and width of the anion exchange composite membrane. Place the anion exchange composite membrane in the test fixture. Different tensile speeds can be used to determine the tensile strength and elongation at break, selected 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.

[0117] a. Tensile strength: The ratio of the maximum load that an anion exchange composite membrane can withstand when it breaks under pure tensile force to the width of the membrane material being stretched. It is divided into transverse and longitudinal tensile strength and is used to evaluate the mechanical strength of the membrane.

[0118] b. Elongation at break: The ratio of the distance between two points at break to the original length under the maximum load before the anion exchange composite membrane breaks. It represents the maximum deformation that an alkaline membrane can withstand before breaking, indicating the membrane's flexibility.

[0119] 2. Swelling performance test

[0120] Test method: Cut the anion exchange composite membrane into 2cm*4cm pieces, place them in 1M KOH solution, change the alkali three times, and test the swelling performance in deionized water at 80℃.

[0121] 3. Electrolysis of water application test

[0122] An anion exchange composite membrane was fabricated into a membrane electrode with an active area of ​​80 cm². 2 The cathode nickel-molybdenum alloy loading is 1.0 mg / cm³. 2 The nickel ferrite loading at the anode is 1.2 mg / cm³. 2 Then, they are assembled into a single-cell electrolytic cell. Under the condition of 60℃, the positive and negative electrodes are connected, and the polarization performance and sheet resistance of the composite film are tested by an electrochemical workstation.

[0123] a. Polarization performance: Using an electrochemical workstation, select the linear voltammetry (LSV) mode, with a current testing range typically 0-80V (based on 80cm). 2 (Definition of active area). Information such as potential and current curves is obtained through testing, and further information processing yields the polarization performance.

[0124] b. Sheet resistance: Using an electrochemical workstation, select the AC impedance test (EIS) mode to test and obtain information such as high-frequency impedance, and then further process the information to obtain the sheet resistance.

[0125] Table 1

[0126]

[0127] Note: In Example 15, the membrane material prepared by the single immersion process had pits on the membrane surface; in Comparative Example 2, the composite homogeneous layer and the mesh separated during short-term testing.

[0128] As can be seen from Table 1:

[0129] 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 this application has universality and can respond to the composite needs of different anion exchange polymers.

[0130] Compared to Examples 1, 5, and 6, with increasing mesh thickness, the composite membrane exhibits higher tensile strength and lower swelling ratio, but also higher sheet resistivity and higher polarization performance. This indicates that a thicker mesh results in better mechanical properties but poorer electrochemical performance of the composite membrane.

[0131] Compared to Examples 1, 7, and 8, the test results of the anion exchange composite membranes were similar under the same composite membrane thickness conditions, indicating that the thickness fluctuations of the first and second membrane layers had no significant impact on the material properties. Compared to Example 13, Examples 13 exhibited higher tensile strength, higher elongation at break, and lower swelling ratio, but also higher sheet resistivity and polarization performance. This demonstrates that different composite membrane thicknesses have a significant impact on mechanical and electrochemical properties; thicker membranes generally result in better mechanical properties but poorer electrochemical properties.

[0132] Compared with Examples 1, 9, 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 that of Examples 1, 9, and 10. The sheet resistivity and polarization performance of Comparative Example 3 are slightly lower than those of Examples 1, 9, and 10. It can be seen that, for the same composite film thickness, an open porosity of 50-70% has no significant effect on electrochemical performance but a weak effect on mechanical properties. When the open porosity is 90%, the electrochemical performance is slightly improved, but the mechanical properties of the film material are significantly reduced.

[0133] Compared with Examples 1, 11, 12 and 14, the sheet resistance and polarization performance of Example 14 are significantly higher. This is because the excessively high viscosity results in poor wetting and composite effect of the anion exchange polymer, and there may be more voids in the composite membrane, which increases the mass transfer resistance and ultimately leads to a deterioration in the electrochemical performance of the composite membrane.

[0134] Compared with the composite film prepared by the two coating processes in Example 1, the composite film prepared by the one immersion process in Example 15 has higher surface resistivity and polarization performance. In addition, the composite film prepared by the one immersion process has pits on its surface, which is caused by the loss of slurry in the mesh pores during the drying stage. Furthermore, the thickness uniformity of the composite film is poor.

[0135] Compared with Comparative Example 1, under the same conditions of anion exchange polymer and anion exchange composite membrane thickness, the tensile strength of Example 1 is much greater than that of Comparative Example 1, indicating that the anion exchange composite membrane in Example 1 exhibits superior 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 application stage. The sheet resistivity and polarization performance of Example 1 and Comparative Example 1 are similar, indicating that the composite membrane under the process of this application can still maintain electrochemical performance comparable to that of the homogeneous membrane in Comparative Example 1.

[0136] Compared with Comparative Example 2, the mechanical properties of Example 6 are similar under the two composite processes, but Example 6 shows better dimensional stability (lower swelling rate). This is mainly attributed to the difference in the binding effect of the reinforcing layer (mesh) on the homogeneous layer (film layer). An excessively thick homogeneous layer weakens the binding effect of the reinforcing layer, thus failing to effectively control the swelling of the composite film. In addition, Comparative Example 2 showed separation between the homogeneous layer and the mesh during short-term testing. An excessively thick homogeneous layer on one side will exacerbate the separation of the two phases.

[0137] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An anion exchange composite membrane, comprising a first membrane layer, a mesh fabric, and a second membrane layer stacked sequentially, wherein both the first membrane layer and the second membrane layer comprise anion exchange polymer, and the mesh fabric has an open porosity of 50% to 70%.

2. The anion exchange composite membrane according to claim 1, wherein, The anion exchange polymer includes one of polyarylpiperidine polymer, polyarylpiperidine polymer, polyarylquinine polymer, and polybenzopyrazole polymer.

3. The anion exchange composite membrane of claim 1, wherein, The anion exchange polymers in the first membrane layer and the second membrane layer are of the same type.

4. The anion exchange composite membrane according to claim 1, wherein, The material of the mesh includes one or more of polyetheretherketone, polyphenylene sulfide, polyethylene, polyethylene terephthalate, polypropylene, and polytetrafluoroethylene.

5. The anion exchange composite membrane according to claim 1, wherein, The first film layer and the second film layer satisfy at least one of the following conditions: The thickness of the first film layer is 10 μm to 40 μm; The thickness of the second film layer is 10μm~40μm.

6. The anion exchange composite membrane according to claim 1, wherein, The mesh fabric meets at least one of the following conditions: The thickness of the mesh fabric is 20μm~80μm; The mesh is made of multiple warp and weft threads interwoven together, with the distance between two adjacent warp threads being 100μm to 200μm and the distance between two adjacent weft threads being 100μm to 200μm.

7. The anion exchange composite membrane according to claim 1, wherein, The mesh fabric meets at least one of the following conditions: The degradation temperature of the mesh fabric is ≥120℃; The contact angle of the mesh with pure water is ≤150°.

8. The anion exchange composite membrane according to claim 1, wherein, The anion exchange polymer satisfies at least one of the following conditions: The anion exchange polymer has an ion exchange capacity of 1.8 mmol / g to 4.0 mmol / g; The degradation temperature of the anion exchange polymer is ≥120℃.

9. A method for preparing anion exchange composite membrane, comprising the following steps: A membrane slurry and a mesh fabric are provided. The membrane slurry is disposed on both sides of the mesh fabric to form a first membrane layer and a second membrane layer, thereby obtaining an anion exchange composite membrane. The membrane slurry contains anion exchange polymer, and the mesh fabric has an open porosity of 50% to 70%.

10. The method for preparing the anion exchange composite membrane according to claim 9, wherein, The membrane slurry meets at least one of the following conditions: The solid content of the membrane slurry is 15%wt~25%wt; The viscosity of the film slurry is 5000 mPa.s@25℃ to 48000 mPa.s@25℃.

11. The method for preparing the anion exchange composite membrane according to claim 9, wherein, The mesh fabric is obtained by soaking in an alcohol solvent.

12. The method for preparing the anion exchange composite membrane according to claim 11, wherein, The soaking treatment meets at least one of the following conditions: The soaking time is 6h~24h; The alcohol solvent includes one or more of methanol, ethanol, and isopropanol.

13. The method for preparing the anion exchange composite membrane according to claim 9, wherein, The step of setting the film slurry on both sides of the mesh to form a first film layer and a second film layer includes: A substrate is provided, and the film slurry is disposed on the substrate to obtain a first wet film layer; One side surface of the mesh fabric is bonded to the side of the first wet film layer opposite to the substrate to obtain a first composite, the first composite comprising the mesh fabric and the first wet film layer. The first composite attached to the surface of the substrate is subjected to a first drying process, and then the film slurry is applied to the other side of the mesh to form a second wet film layer. Then, a second drying process is performed to form the first film layer and the second film layer.

14. The method for preparing the anion exchange composite membrane according to claim 13, wherein, The temperature of the first drying is 40℃~60℃, and the drying time is 5min~50min.

15. The method for preparing the anion exchange composite membrane according to claim 13, wherein, The second drying process includes drying at 40℃~60℃ for 1h~2h, drying at 70℃~90℃ for 2h~3h, and drying at 60℃~80℃ for 1h~2h in sequence.

16. An apparatus comprising an anion exchange composite membrane as described in any one of claims 1 to 8, or an anion exchange composite membrane prepared by the method described in any one of claims 9 to 15.

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