Composite anion exchange membrane and preparation method thereof

Abstract

The invention provides a composite anion exchange membrane and a preparation method thereof. The composite anion exchange membrane comprises a polyaryl piperidine polymer and a polyvinyl alcohol polymer, the structural general formula of the composite anion exchange membrane is shown in the specification, x represents the degree of polymerization, and the value range of x is 10-1000; and Ar is selected from any one of arylene groups of C12 to C40. Due to the introduction of the polyvinyl alcohol polymer, the mechanical strength of the composite anion-exchange membrane is remarkably enhanced, the integrity and functionality of the composite anion-exchange membrane can be kept under the action of high-pressure or high-strength mechanical stress, and the common physical damage problem of a traditional anion-exchange membrane in the operation process is avoided. Therefore, the composite anion exchange membrane not only has higher ion exchange capacity, but also has additional mechanical property improvement through the synergistic effect of the polyaryl piperidine polymer and the polyvinyl alcohol polymer.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a composite anion exchange membrane and its preparation method. Background Technology

[0002] Anion exchange membranes (AEMs) are widely used in electrolyzers, fuel cells, carbon dioxide reduction, hard water softening, desalination, pure water production, hydrometallurgy, rare element separation, pharmaceuticals, sugar refining, and amino acid adsorption. In the field of hydrogen production through water electrolysis, AEMs are often used to separate hydrogen gas between the anode and cathode and to provide anion transport channels. The effective active component of anion exchange membranes is anion exchange resin, which typically consists of a polymer backbone and charged ion-conducting groups connected by side chains of varying lengths.

[0003] Although anion exchange membranes play an important role in electrochemical devices, the mechanical properties of existing anion exchange membranes are insufficient to meet the actual needs of fuel cell stack assembly. Summary of the Invention

[0004] The main objective of this invention is to provide a composite anion exchange membrane and its preparation method, so as to solve the problem of poor mechanical properties of anion exchange membranes in the prior art.

[0005] To achieve the above objectives, according to one aspect of the present invention, a composite anion exchange membrane is provided, comprising a polyarylpiperidine polymer and a polyvinyl alcohol polymer, wherein the general structural formula of the composite anion exchange membrane is as follows:

[0006]

[0007] Where x represents the degree of polymerization, and the value of x ranges from 10 to 1000; Ar is selected from C 12 ~C 40 Any of the aryl groups.

[0008] Furthermore, the mass ratio of the above-mentioned polyvinyl alcohol polymer to the polyarylpiperidine polymer is 1:1 to 100, preferably 1:5 to 25; the polyvinyl alcohol polymer is a modified polyvinyl alcohol obtained by condensation of polyvinyl alcohol and glutaraldehyde, or the polyvinyl alcohol polymer is polyvinyl alcohol.

[0009] Furthermore, the value of x above ranges from 100 to 500; and / or Ar is selected from C. 12 ~C 24 Any of the arylene groups, preferably Ar is selected from any of the following substituents:

[0010]

[0011] in This indicates the linkage position of Ar in polyarylpiperidine polymers.

[0012] Furthermore, the tensile strength of the composite anion exchange membrane is 15–100 MPa, the ionic conductivity is 80–150 mS / cm, and the elongation at break is 20–150%.

[0013] According to another aspect of the present invention, a method for preparing the aforementioned composite anion exchange membrane is provided, the method comprising: step S1, mixing raw materials including polyvinyl alcohol, polyarylpiperidine polymer and solvent to obtain a mixture; step S2, placing the mixture in a groove of a flat glass plate, and sequentially drying and peeling to obtain a composite anion exchange membrane.

[0014] Furthermore, in step S1 above, the molecular weight of polyvinyl alcohol is 25,000 to 300,000 Da; and / or the viscosity of polyvinyl alcohol is 20 to 500 mPa·s.

[0015] Furthermore, in step S1 above, the solvent is selected from any one or more of dimethyl sulfoxide and N-methylpyrrolidone.

[0016] Furthermore, in step S1 above, the solid content of the mixture is 2-30%.

[0017] Furthermore, in step S2 above, the drying temperature is 60–120°C, and the drying time is 1–48 hours.

[0018] Furthermore, the above preparation method also includes: immersing the composite anion exchange membrane in a glutaraldehyde aqueous solution; wherein the immersion temperature is 20-70°C and the immersion time is 1-24 h; and / or the mass concentration of the glutaraldehyde aqueous solution is 0.1-10 wt%, preferably 0.5-2 wt%.

[0019] Applying the technical solution of this invention, the composite anion exchange membrane of this application comprises a polyarylpiperidine polymer and a polyvinyl alcohol polymer. The polyarylpiperidine polymer provides a highly efficient anion exchange channel for the composite anion exchange membrane while maintaining effective blocking of cations and electrons, ensuring directional ion transport during the electrochemical process and improving the working efficiency and energy conversion rate of the electrochemical device. The introduction of the polyvinyl alcohol polymer significantly enhances the mechanical strength of the composite anion exchange membrane, maintaining its integrity and functionality under high pressure or high-intensity mechanical stress, avoiding the physical damage problems commonly encountered in traditional anion exchange membranes during operation. Thus, through the synergistic effect of the polyarylpiperidine polymer and the polyvinyl alcohol polymer, the composite anion exchange membrane possesses both high ion exchange capacity and additional improved mechanical properties. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0021] As analyzed in the background section of this application, the existing technology has the problem of poor mechanical properties of anion exchange membranes. In order to solve the above problems, this application provides a composite anion exchange membrane and its preparation method.

[0022] In a typical embodiment of this application, an anion exchange polymer is provided. The composite anion exchange membrane comprises a polyarylpiperidine polymer and a polyvinyl alcohol polymer, wherein the general structural formula of the composite anion exchange membrane is as follows:

[0023]

[0024] Where x represents the degree of polymerization, and the value of x ranges from 10 to 1000; Ar is selected from C 12 ~C 40 Any of the aryl groups.

[0025] The composite anion exchange membrane described in this application comprises polyarylpiperidine polymers and polyvinyl alcohol polymers. The polyarylpiperidine polymers provide highly efficient anion exchange channels while effectively blocking cations and electrons, ensuring directional ion transport during the electrochemical process and improving the efficiency and energy conversion rate of the electrochemical equipment. The introduction of polyvinyl alcohol polymers significantly enhances the mechanical strength of the composite anion exchange membrane, maintaining its integrity and functionality under high pressure or high-intensity mechanical stress, thus avoiding the physical damage problems commonly encountered in traditional anion exchange membranes during operation. Therefore, through the synergistic effect of the polyarylpiperidine polymers and polyvinyl alcohol polymers, the composite anion exchange membrane possesses both high ion exchange capacity and additional mechanical performance enhancements.

[0026] In addition, Ar is C 12 ~C 40 The presence of arylene groups indicates that composite anion exchange membranes can support large and complex aromatic structures, which can provide additional functionality, such as improving the thermal stability, chemical stability, or adding specific electrochemical active sites to the composite anion exchange membrane.

[0027] The value of x ranges from 10 to 1000, which means that the overall mechanical and electrochemical properties of the composite anion exchange membrane can be adjusted by regulating the degree of polymerization, so as to adapt it to different application scenarios.

[0028] In one embodiment of this application, the mass ratio of the polyvinyl alcohol polymer to the polyarylpiperidine polymer is 1:1 to 100, preferably 1:5 to 25; the polyvinyl alcohol polymer is a modified polyvinyl alcohol after condensation of polyvinyl alcohol and glutaraldehyde, or the polyvinyl alcohol polymer is polyvinyl alcohol.

[0029] The preferred mass ratio of polyvinyl alcohol polymers to polyarylpiperidine polymers helps to balance the mechanical and electrochemical properties of the composite anion exchange membrane, thereby obtaining a composite anion exchange membrane with better overall performance. This allows it to play a more efficient role in various electrochemical applications, such as fuel cells and water-to-hydrogen production, thus improving energy conversion efficiency.

[0030] The addition of polyvinyl alcohol (PVA) not only increases the membrane's toughness but also improves its tensile strength, enabling the membrane to withstand higher operating pressures in electrochemical devices. The PVA polymer can be native PVA or PVA modified by condensation with glutaraldehyde. The modified PVA provides additional crosslinking points, further enhancing the membrane's structural stability and mechanical strength, and improving the chemical stability of the composite anion exchange membrane. This means the membrane is less prone to chemical degradation during long-term use, maintaining stable performance and extending its service life.

[0031] In one embodiment of this application, the value of x ranges from 100 to 500; and / or Ar is selected from C. 12 ~C 24 Any of the arylene groups, preferably Ar is selected from any of the following substituents:

[0032]

[0033] in

[0034] This indicates the linkage position of Ar in polyarylpiperidine polymers.

[0035] The preferred value of x is in the range of 100 to 500, which is more conducive to obtaining a composite anion exchange membrane with excellent comprehensive performance.

[0036] Thanks to the inherent alkali resistance of aryl groups, the preferred Ar structure enhances the stability of the polyarylpiperidine polymer backbone in strongly alkaline environments, thereby resisting chemical attack and reducing the likelihood of backbone breakage or degradation. Furthermore, the preferred aryl structure optimizes the arrangement and connectivity of ion transport channels, promoting efficient ion conduction and improving the ionic conductivity of the anion exchange membrane. It also improves other physical properties of the anion exchange membrane, such as mechanical strength, flexibility, and thermal stability, making the membrane more durable and reliable in complex application environments.

[0037] In one embodiment of this application, the tensile strength of the composite anion exchange membrane is 15-100 MPa, the ionic conductivity of the composite anion exchange membrane is 80-150 mS / cm, and the elongation at break of the composite anion exchange membrane is 20-150%.

[0038] The above parameters indicate that the composite anion exchange membrane possesses high resistance to external forces without deformation, high conductivity, and good ductility. Using such a composite anion exchange membrane ensures its physical stability during long-term operation, while the optimized ionic conductivity guarantees the durability of its electrochemical performance. This means that the composite anion exchange membrane can maintain its electrochemical efficiency for a long time, reducing the frequency of maintenance and replacement, and lowering operating costs.

[0039] In another typical embodiment of this application, a method for preparing the above-mentioned composite anion exchange membrane is provided, characterized in that the preparation method includes: step S1, mixing raw materials including polyvinyl alcohol, polyarylpiperidine polymer and solvent to obtain a mixture; step S2, placing the mixture in a groove of a flat glass plate, and successively drying and peeling to obtain a composite anion exchange membrane.

[0040] Step S1 of the above preparation method ensures that the two main polymers are fully dispersed and uniformly combined at the molecular level, which is crucial for preparing stable composite anion exchange membranes. The continuous preparation process in step S2 is not only simple and efficient, but also easy to operate, reducing reliance on complex equipment and minimizing potential instability factors such as bubbles and cracks, thereby improving the production efficiency and yield of composite anion exchange membranes.

[0041] In one embodiment of this application, in step S1 above, the molecular weight of polyvinyl alcohol is 25,000 to 300,000 Da; and / or the viscosity of polyvinyl alcohol is 20 to 500 mPa·s.

[0042] The preferred molecular weight range of polyvinyl alcohol (PVA) provides sufficient toughness to the composite anion exchange membrane, making it less prone to breakage under external forces and enhancing its overall mechanical properties. Selecting a viscosity range within this range facilitates mixing PVA with other components to form a mixture with good flowability and uniformity, thereby enabling the formation of a smooth, defect-free membrane structure in subsequent film-forming processes. Furthermore, this viscosity also helps control the uniform thickness of the composite anion exchange membrane during the drying process, which is beneficial for improving the membrane's electrochemical performance.

[0043] In one embodiment of this application, in step S1 above, the solvent is selected from any one or more of dimethyl sulfoxide and N-methylpyrrolidone.

[0044] Thanks to the good polarity and solubility of the above solvents, they are conducive to the full dispersion of polyvinyl alcohol and polyarylpiperidine polymers, thereby improving the uniformity of the composite anion exchange membrane.

[0045] In one embodiment of this application, in step S1 above, the solid content of the mixture is 2-30%.

[0046] The solid content of the mixture directly determines the structure and performance of the membrane material during the film formation process. Too low a solid content may result in an excessively thin membrane with insufficient mechanical strength and electrochemical performance; while too high a solid content may lead to an excessively thick membrane with low porosity, affecting ion transport efficiency. Therefore, the preferred solid content range described above helps to form a composite anion exchange membrane with stable structure, moderate thickness, and superior performance.

[0047] To further improve the uniformity and integrity of the film formation process, in one embodiment of this application, it is preferred that the drying temperature in step S2 is 60-120°C and the drying time is 1-48 hours.

[0048] In one embodiment of this application, the above preparation method further includes: immersing the composite anion exchange membrane in a glutaraldehyde aqueous solution; wherein the immersion temperature is 20-70°C and the immersion time is 1-24 h; and / or the mass concentration of the glutaraldehyde aqueous solution is 0.1-10 wt%, preferably 0.5-2 wt%.

[0049] Glutaraldehyde is a highly efficient crosslinking agent that can form additional chemical bonds between polymer chains in the membrane. Under the temperature, time, and concentration conditions described above for the immersion treatment, glutaraldehyde can react with the active groups in polyvinyl alcohol to form a stable crosslinked network, significantly improving the chemical stability and mechanical strength of the membrane and reducing physical or chemical degradation during use.

[0050] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0051] Example 1: The aryl group is p-terphenyl, x = 100

[0052] (1) Synthesis of intermediate polymer: 2.3 g (10.0 mmol) of p-terphenyl was weighed into a 100 mL three-necked flask, and 1.08 g (9.5 mmol) of N-methyl-4-piperidinone and 0.087 g of trifluoroacetophenone (0.5 mmol) were added. 10 mL of dichloromethane was added to dissolve the reactants. 12 mL of trifluoromethanesulfonic acid and 1 mL of trifluoroacetic acid were added at 0 °C, and the mixture was stirred mechanically for 6 hours. The viscous purple product was poured into 1 M K2CO3 solution and soaked at room temperature for 24 hours. The product was filtered to obtain a white solid product, which was thoroughly washed with deionized water and dried to obtain the intermediate polymer.

[0053] (2) Synthesis of the functionalized polymer: 1.2 g of the above intermediate polymer was weighed into a 100 mL single-necked flask, 15 mL of dimethyl sulfoxide was added, and 150 μL of trifluoroacetic acid was added to promote polymer dissolution. After complete dissolution, 0.36 g of potassium carbonate and 0.32 g of intermediate 1 were added, and the reaction was carried out at 60 °C for 16 hours. Then, 300 μL of iodomethane was added, and the reaction was carried out at room temperature for 24 hours. The reaction product was poured into ethyl acetate to precipitate a yellow precipitate. After washing several times with ethyl acetate, the precipitate was washed with water and dried to obtain the functionalized polymer with the I- anion.

[0054] (3) Film formation, crosslinking and ion exchange: Weigh 1g of the above anion exchange polymer and 0.2g of polyvinyl alcohol, add 50mL of dimethyl sulfoxide; after fully dissolving, pour into the groove of a flat glass plate, and dry at 80℃ for 48 hours to form a film. Peel the film off the glass plate.

[0055] Example 2: The aryl group is p-terphenyl, x = 500

[0056] (1) Synthesis of intermediate polymer: 2.3 g (10.0 mmol) of p-terphenyl was weighed into a 100 mL three-necked flask, and 1.08 g (9.5 mmol) of N-methyl-4-piperidinone and 0.087 g of trifluoroacetophenone (0.5 mmol) were added. 10 mL of dichloromethane was added to dissolve the reactants. 12 mL of trifluoromethanesulfonic acid and 1 mL of trifluoroacetic acid were added at 0 °C, and the mixture was stirred mechanically for 12 hours. The viscous purple product was poured into 1 M K2CO3 solution and soaked at room temperature for 24 hours. The product was filtered to obtain a white solid product, which was thoroughly washed with deionized water and dried to obtain the intermediate polymer.

[0057] (2) Synthesis of the functionalized polymer: 1.2 g of the above intermediate polymer was weighed into a 100 mL single-necked flask, 15 mL of dimethyl sulfoxide was added, and 150 μL of trifluoroacetic acid was added to promote polymer dissolution. After complete dissolution, 0.36 g of potassium carbonate and 0.32 g of intermediate 1 were added, and the reaction was carried out at 60 °C for 16 hours. Then, 300 μL of iodomethane was added, and the reaction was carried out at room temperature for 24 hours. The reaction product was poured into ethyl acetate to precipitate a yellow precipitate. After washing several times with ethyl acetate, the precipitate was washed with water and dried to obtain the functionalized polymer with the I- anion.

[0058] (3) Film formation, crosslinking and ion exchange: Weigh 1g of the above anion exchange polymer and 0.2g of polyvinyl alcohol, add 50mL of dimethyl sulfoxide; after fully dissolving, pour into the groove of a flat glass plate, and dry at 80℃ for 48 hours to form a film. Peel the film off the glass plate.

[0059] Example 3: The aryl group is p-terphenyl, x = 50

[0060] (1) Synthesis of intermediate polymer: 2.3 g (10.0 mmol) of p-terphenyl was weighed into a 100 mL three-necked flask, and 1.08 g (9.5 mmol) of N-methyl-4-piperidinone and 0.087 g of trifluoroacetophenone (0.5 mmol) were added. 10 mL of dichloromethane was added to dissolve the reactants. 12 mL of trifluoromethanesulfonic acid and 1 mL of trifluoroacetic acid were added at 5 °C, and the mixture was stirred mechanically for 6 hours. The viscous purple product was poured into 1 M K2CO3 solution and soaked at room temperature for 24 hours. The product was filtered to obtain a white solid product, which was thoroughly washed with deionized water and dried to obtain the intermediate polymer.

[0061] (2) Synthesis of the functionalized polymer: 1.2 g of the above intermediate polymer was weighed into a 100 mL single-necked flask, 15 mL of dimethyl sulfoxide was added, and 150 μL of trifluoroacetic acid was added to promote polymer dissolution. After complete dissolution, 0.36 g of potassium carbonate and 0.32 g of intermediate 1 were added, and the reaction was carried out at 60 °C for 16 hours. Then, 300 μL of iodomethane was added, and the reaction was carried out at room temperature for 24 hours. The reaction product was poured into ethyl acetate to precipitate a yellow precipitate. After washing several times with ethyl acetate, the precipitate was washed with water and dried to obtain the functionalized polymer with the I- anion.

[0062] (3) Film formation, crosslinking and ion exchange: Weigh 1g of the above anion exchange polymer and 0.2g of polyvinyl alcohol, add 50mL of dimethyl sulfoxide; after fully dissolving, pour into the groove of a flat glass plate, and dry at 80℃ for 48 hours to form a film. Peel the film off the glass plate.

[0063] Example 4: The aryl group is biphenyl, x = 100

[0064] (1) Synthesis of intermediate polymer: 1.54 g (10.0 mmol) of biphenyl was weighed into a 100 mL three-necked flask, and 1.08 g (9.5 mmol) of N-methyl-4-piperidinone and 0.087 g of trifluoroacetophenone (0.5 mmol) were added. 10 mL of dichloromethane was added to dissolve the reactants. 12 mL of trifluoromethanesulfonic acid and 1 mL of trifluoroacetic acid were added at 0 °C, and the mixture was stirred mechanically for 6 hours. The viscous purple product was poured into 1 M K2CO3 solution and soaked at room temperature for 24 hours. The product was filtered to obtain a white solid product, which was thoroughly washed with deionized water and dried to obtain the intermediate polymer.

[0065] (2) Synthesis of the functionalized polymer: 1.2 g of the above intermediate polymer was weighed into a 100 mL single-necked flask, 15 mL of dimethyl sulfoxide was added, and 150 μL of trifluoroacetic acid was added to promote polymer dissolution. After complete dissolution, 0.36 g of potassium carbonate and 0.32 g of intermediate 1 were added, and the reaction was carried out at 60 °C for 16 hours. Then, 300 μL of iodomethane was added, and the reaction was carried out at room temperature for 24 hours. The reaction product was poured into ethyl acetate to precipitate a yellow precipitate. After washing several times with ethyl acetate, the precipitate was washed with water and dried to obtain the functionalized polymer with the I- anion.

[0066] (3) Film formation, crosslinking and ion exchange: Weigh 1g of the above anion exchange polymer and 0.2g of polyvinyl alcohol, add 50mL of dimethyl sulfoxide; after fully dissolving, pour into the groove of a flat glass plate, and dry at 80℃ for 48 hours to form a film. Peel the film off the glass plate.

[0067] Example 5:

[0068] The difference from Example 1 is that the polyvinyl alcohol is 0.2g, and the mass ratio of polyvinyl alcohol to polyarylpiperidine polymer is 1:25, ultimately resulting in a composite anion exchange membrane.

[0069] Example 6:

[0070] The difference from Example 1 is that the polyvinyl alcohol is 0.2g, and the mass ratio of polyvinyl alcohol to polyarylpiperidine polymer is 1:100, ultimately resulting in a composite anion exchange membrane.

[0071] Example 7:

[0072] The difference from Example 1 is that the molecular weight of polyvinyl alcohol is 300,000 Da and the viscosity of polyvinyl alcohol is 500 mPa·s, resulting in a composite anion exchange membrane.

[0073] Example 8:

[0074] The difference from Example 1 is that the molecular weight of polyvinyl alcohol is 20,000 Da and the viscosity of polyvinyl alcohol is 10 mPa·s, resulting in a composite anion exchange membrane.

[0075] Example 9:

[0076] The difference from Example 1 is that the drying temperature is 80°C and the drying time is 48 hours, resulting in a composite anion exchange membrane.

[0077] Example 10:

[0078] The difference from Example 1 is that the solvent is N-methylpyrrolidone, and a composite anion exchange membrane is finally obtained.

[0079] Example 11:

[0080] The difference from Example 1 is that the composite anion exchange membrane was soaked in a glutaraldehyde aqueous solution at a temperature of 70°C for 24 hours, and the mass concentration of the glutaraldehyde aqueous solution was 2wt%, thus obtaining the composite anion exchange membrane.

[0081] Example 12:

[0082] The difference from Example 11 is that the mass concentration of the glutaraldehyde aqueous solution is 0.1 wt%, and a composite anion exchange membrane is finally obtained.

[0083] Comparative Example 1

[0084] The difference from Example 1 is that the polyarylepiperidine polymer of Example 1 is used directly for film formation to obtain anion exchange membrane.

[0085] Performance testing:

[0086] Tensile strength: The tensile strength shall be tested in accordance with the method specified in Chapter 8 of GB / T 20242.3-2022.

[0087] Elongation at break: The tensile strain at break was tested according to the method specified in Chapter 8 of GB / T 20242.3-2022.

[0088] Ionic conductivity: The OH- ions in pure water were measured using a four-electrode AC impedance method on a fully wet anion exchange membrane. - The ionic conductivity was tested under the following conditions: the sample was assembled in a dedicated test fixture and immersed in pure water at 80°C. An electrochemical workstation was used to measure the AC impedance spectrum of the sample, with an impedance frequency range of 1 Hz to 4*10⁻⁶ Hz. 4 With a Hz perturbation voltage of 10mV, the impedance value of the sample is read from the intersection of the high-frequency part of the spectrum with the real axis, and the ionic conductivity is calculated.

[0089] The test results are listed in Table 1.

[0090] Table 1

[0091]

[0092] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0093] The composite anion exchange membrane described in this application comprises polyarylpiperidine polymers and polyvinyl alcohol polymers. The polyarylpiperidine polymers provide highly efficient anion exchange channels while effectively blocking cations and electrons, ensuring directional ion transport during the electrochemical process and improving the efficiency and energy conversion rate of the electrochemical equipment. The introduction of polyvinyl alcohol polymers significantly enhances the mechanical strength of the composite anion exchange membrane, maintaining its integrity and functionality under high pressure or high-intensity mechanical stress, thus avoiding the physical damage problems commonly encountered in traditional anion exchange membranes during operation. Therefore, through the synergistic effect of the polyarylpiperidine polymers and polyvinyl alcohol polymers, the composite anion exchange membrane possesses both high ion exchange capacity and additional mechanical performance enhancements.

[0094] The above are merely embodiments of the present invention and are not intended to limit the invention. Those skilled in the art will recognize that the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite anion exchange membrane, characterized in that, The composite anion exchange membrane comprises polyarylpiperidine polymers and polyvinyl alcohol polymers, wherein the general structural formula of the composite anion exchange membrane is as follows: Where x represents the degree of aggregation, and the value of x ranges from 10 to 1000; Ar is selected from C 12 ~C 40 Any of the aryl groups.

2. The composite anion exchange membrane according to claim 1, characterized in that, The mass ratio of the polyvinyl alcohol polymer to the polyarylpiperidine polymer is 1:1 to 100, preferably 1:5 to 25; the polyvinyl alcohol polymer is a modified polyvinyl alcohol obtained by condensation of polyvinyl alcohol and glutaraldehyde, or the polyvinyl alcohol polymer is polyvinyl alcohol.

3. The composite anion exchange membrane according to claim 1 or 2, characterized in that, The value of x ranges from 100 to 500; And / or the Ar mentioned is selected from C 12 ~C 24 Any of the arylene groups, preferably Ar is selected from any of the following substituents: in This indicates the connection position of Ar in the polyarylpiperidine polymer.

4. The composite anion exchange membrane according to any one of claims 1 to 3, characterized in that, The composite anion exchange membrane has a tensile strength of 15–100 MPa, an ionic conductivity of 80–150 mS / cm, and an elongation at break of 20–150%.

5. A method for preparing the composite anion exchange membrane according to any one of claims 1 to 4, characterized in that, The preparation method includes: Step S1: Mix the raw materials, including polyvinyl alcohol, polyarylpiperidine polymer and solvent, to obtain a mixture; Step S2: The mixture is placed in the groove of a flat glass plate, and after drying and peeling, a composite anion exchange membrane is obtained.

6. The preparation method according to claim 5, characterized in that, In step S1, the molecular weight of the polyvinyl alcohol is 25,000 to 300,000 Da; and / or the viscosity of the polyvinyl alcohol is 20 to 500 mPa·s.

7. The preparation method according to claim 5, characterized in that, In step S1, the solvent is selected from any one or more of dimethyl sulfoxide and N-methylpyrrolidone.

8. The preparation method according to claim 5, characterized in that, In step S1, the solid content of the mixture is 2-30%.

9. The preparation method according to claim 5, characterized in that, In step S2, the drying temperature is 60–120°C, and the drying time is 1–48 hours.

10. The preparation method according to claim 5, characterized in that, The preparation method further includes: The composite anion exchange membrane was immersed in an aqueous solution of glutaraldehyde. The soaking temperature is 20–70°C, and the soaking time is 1–24 hours. And / or the mass concentration of the glutaraldehyde aqueous solution is 0.1 to 10 wt%, preferably 0.5 to 2 wt%.

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