Preparation method of multilayer anion exchange composite membrane based on hot-pressing assembly

Abstract

The invention belongs to the technical field of ion exchange membranes, and relates to a preparation method of a multilayer anion exchange composite membrane based on hot-pressing assembly. And carrying out hot-pressing assembly on the plurality of element composite membranes to obtain the multilayer anion exchange composite membrane, the element composite membrane comprises a base membrane and ion exchange resin; the glass transition temperature of the ion exchange resin is 60-130 DEG C; the temperature of the hot pressing assembly is 80-140 DEG C. In the composite film, each layer of element composite film contains a substrate, so that the composite film has excellent mechanical property and toughness, and the effect of layer-by-layer reinforcement is realized. By utilizing the characteristic that the polystyrene modified ion exchange resin can be dissolved in a low-boiling-point alcohol solvent, the use of a high-boiling-point organic solvent is avoided, and the preparation of the element composite membrane at room temperature is realized. Meanwhile, the polystyrene modified ion exchange resin has the characteristic of low glass transition temperature, and layer-by-layer combination with controllable layer number can be quickly and conveniently carried out through hot pressing, so that the phenomenon of incompatibility is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of ion exchange membranes, and relates to a preparation method of a multilayer anion exchange composite membrane based on hot pressing assembly. Background Art

[0002] As a zero-carbon energy source, hydrogen energy is becoming increasingly important in the energy structure. Anion exchange membrane fuel cells (HEMFC) and water electrolysis (HEMWE) are electrochemical devices for using hydrogen and producing hydrogen, which have the characteristics of high efficiency and environmental friendliness. The coupling of the two can achieve the sustainable development of green electricity - green hydrogen - green electricity, showing great application prospects.

[0003] Anion exchange membrane (HEM) is one of the key materials for HEMFC and HEMWE, and plays a crucial role in performance and stability. In HEMFC, the oxygen reduction reaction occurs at the cathode, consuming oxygen and water to produce hydroxide ions, which are transported to the anode through the HEM. In HEMWE, the hydrogen evolution reaction occurs at the cathode, consuming water to produce hydroxide ions and transporting them to the anode. Therefore, the stable operation of HEMFC and HEMWE is inseparable from the water balance, and the HEM is the place to achieve a good water balance. The water absorption of the membrane is closely related to the water transport and water balance in the membrane. Improving the water absorption of the membrane can improve water transport and thus affect the overall water balance. However, excessive water absorption will cause a decrease in the water plasticization resistance of the membrane, resulting in attenuation of the mechanical properties of the membrane, which is not conducive to the mechanical stability of the membrane. Through the composite strategy, the mechanical properties of the membrane can be improved, but it often limits the water absorption of the membrane, which is not conducive to water transport and ion conduction. Patent CN 116791144 A has a large surface resistance and thickness for the three-layer diaphragm for water electrolysis prepared by roll pressing; the mechanical strength of the multilayer composite membrane prepared by the doctor blade method in Patent CN117895039 A is poor; the water absorption rate of the multilayer composite membrane prepared by multiple casting in Patent CN 112510235 A is low. Summary of the Invention

[0004] Aiming at the technical problems existing in the prior art, the present invention provides a preparation method of a multilayer anion exchange composite membrane based on hot pressing assembly. The ion exchange composite membrane has the characteristics of excellent water transport and mechanical properties, and solves the dilemma of the balance between mechanical properties and water transport.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] On the one hand, the present invention provides a preparation method of a multilayer anion exchange composite membrane, including the following steps: hot pressing and assembling a plurality of elementary composite membranes to obtain the multilayer anion exchange composite membrane; the elementary composite membrane includes a base membrane and an ion exchange resin; the glass transition temperature of the ion exchange resin is 60 - 130 °C; the temperature of the hot pressing assembly is 80 - 140 °C.

[0007] In the above technical solution, further, the base film is at least one of ePTFE, ETFE, PVDF, PE, PP, and PEEK; the thickness of the base film is 3-30 μm.

[0008] In the above technical solution, further, the ion exchange resin is a polystyrene-modified ion exchange resin, and its chemical structure is shown in formula (I):

[0009]

[0010] In formula (I):

[0011] x = 5-100, n = 2-10;

[0012] one of.

[0013] In the above technical solution, further, the preparation method of the polystyrene-modified ion exchange resin includes the following steps:

[0014] (1) Under a nitrogen atmosphere, dissolve polystyrene particles in dichloromethane, then add monomer 1 and anhydrous aluminum trichloride, and react at 25 °C for 12-24 h. Precipitate the product, wash, filter, and dry to obtain product A; monomer 1 is shown in formula (II):

[0015]

[0016] In formula (II): m = 0-8, X is a halogen;

[0017] (2) Dissolve product A in dichloromethane, add trifluoroacetic acid and triethylsilane, stir at 15-25 °C for 48 h. After the reaction is completed, quench trifluoroacetic acid with 1-3 M KOH solution and wash with water until neutral. Precipitate the product, wash, filter, and dry to obtain product B;

[0018] (3) Dissolve product B in an aprotic polar solvent, add monomer 2, and react at 25-80 °C for 12-48 h. Precipitate the product, wash, filter, and dry to obtain the polystyrene-modified ion exchange resin;

[0019] The monomer 2 is one of.

[0020] In the above technical solution, further, in step (1), the concentration of polystyrene dissolved in dichloromethane is 0.05-0.1 g / mL, the molar ratio of monomer 1 to polystyrene is (0.05-2):1, and the molar ratio of anhydrous aluminum trichloride to polystyrene is (0.1-2):1.

[0021] In the above technical solution, further, in step (2), the concentration of product A dissolved in dichloromethane is 0.02 - 0.1 g / mL, the molar ratio of trifluoroacetic acid to product A is (1 - 15):1, and the molar ratio of triethylsilane to product A is (1 - 5):1.

[0022] In the above technical solution, further, in step (3), the concentration of product B dissolved in an aprotic polar solvent is 0.02 - 0.1 g / mL, the aprotic polar solvent is one of DMSO, NMP, DMF, and DMAc, and the molar ratio of monomer 2 to product B is (1 - 5):1.

[0023] In the above technical solution, further, the preparation method of the elementary composite membrane includes the following steps:

[0024] Dissolve the polystyrene-modified ion exchange resin in ethanol to obtain a resin solution, scrape the resin solution onto the base membrane, and dry it to obtain the elementary composite membrane; the concentration of the resin solution is 0.02 - 0.1 g / mL.

[0025] In the above technical solution, further, the drying temperature is 20 - 50 °C, and the drying time is 0.5 - 12 h.

[0026] In the above technical solution, further, the specific method of hot pressing is as follows:

[0027] Stack the elementary composite membranes layer by layer and lay them flat on a hot press, preheat at 80 - 100 °C for 10 - 30 min, then apply a pressure of 2 - 10 MPa, adjust the temperature to 80 - 140 °C and maintain it for 30 - 60 min to obtain a multi-layer anion exchange composite membrane.

[0028] On the other hand, the present invention provides an application of the anion exchange composite membrane prepared by the above preparation method in anion exchange membrane fuel cells and electrolysis of water.

[0029] The beneficial effects of the present invention are as follows:

[0030] (1) The present invention provides a preparation method of a multi-layer anion exchange composite membrane, which uses a base membrane and a resin with a low glass transition temperature to achieve hot pressing at a low temperature (80 - 140 °C). The multi-layer anion exchange composite membrane with adjustable thickness is prepared by hot pressing. Through multi-layer composite, layer by layer strengthening, the mechanical properties are further improved, and the problem of incompatibility between layers is eliminated, and the combination between layers is firm; the resin with a low glass transition temperature realizes hot pressing at a low temperature, avoiding the process of high-temperature drying, avoiding cumbersome layer-by-layer casting or rolling, and at the same time solving the problem of polymer degradation caused by high-temperature hot pressing.

[0031] (2) The present invention uses a polystyrene-modified ion exchange resin with strong water absorption and water transmission properties as a resin with a low glass transition temperature, combines it with a base film, endows the anion exchange composite membrane with the characteristics of excellent water transmission and mechanical properties, and solves the dilemma of the balance between mechanical properties and water transmission; by utilizing the characteristic that the polystyrene-modified ion exchange resin is soluble in low-boiling-point alcohol solvents, the use of high-boiling-point solvents is avoided.

[0032] Based on the above beneficial effects, the multi-layer anion exchange composite membrane in the present invention can be promoted in the related fields of anion exchange membranes. Description of the Drawings

[0033] Figure 1 It is the NMR characterization diagram of the polystyrene-modified ion exchange resin in Example 1;

[0034] Figure 2 It is the optical photograph of the elementary composite membrane in Example 1;

[0035] Figure 3 It is the scanning electron microscope diagram of the elementary composite membrane in Example 1;

[0036] Figure 4 It is the water absorption rate diagram of the multi-layer anion exchange composite membranes prepared in Examples 1-3 and Example 6;

[0037] Figure 5 It is the mechanical property diagram of the multi-layer anion exchange composite membranes prepared in Examples 1-3;

[0038] Figure 6 It is the NMR characterization diagram of the polystyrene-modified ion exchange resin in Example 6. Detailed Description of the Invention

[0039] The following non-limiting examples can enable those of ordinary skill in the art to understand the present invention more comprehensively, but do not limit the present invention in any way.

[0040] Example 1

[0041] This example provides a preparation method of a multi-layer anion exchange composite membrane, including the following steps:

[0042] (1) Preparation of the polystyrene-modified ion exchange resin:

[0043] (1.1) Under a nitrogen atmosphere, 10 g of polystyrene particles are dissolved in 150 ml of dichloromethane to obtain a 6.67% (w / v) solution, and then 8.20 g of 6-bromohexanoyl chloride and 7.68 g of anhydrous aluminum trichloride are added, and the reaction is carried out at 25 °C for 15 h. After the reaction is completed, the reaction solution is poured into an appropriate amount of ethanol to precipitate the product, and the product is washed with ethanol several times, filtered, and dried in vacuo at 30 °C to obtain product A;

[0044] (1.2) Dissolve 10 g of product A in 300 ml of dichloromethane to obtain a 0.033 g / ml solution. Add 65.17 g of trifluoroacetic acid and 9.97 g of triethylsilane, and stir at 25 °C for 48 h. After the reaction is completed, quench trifluoroacetic acid with 1 M KOH solution and wash with water until neutral. Pour the organic phase into ethanol to precipitate the product and wash it with ethanol multiple times. Filter and dry in vacuum at 30 °C to obtain product B;

[0045] (1.3) Take 10 g of product B and dissolve it in 200 ml of NMP to obtain a 0.05 g / mL solution. Then add 13.13 g of quinuclidine and react at 60 °C for 24 h. After the reaction is completed, pour the reaction solution into ethyl acetate to precipitate the product and wash it with ethyl acetate multiple times. Filter and dry in vacuum at 30 °C to obtain polystyrene-modified ion exchange resin;

[0046] (2) Preparation of the elementary composite membrane:

[0047] Dissolve the polystyrene-modified ion exchange resin in ethanol to obtain a 0.05 g / mL resin solution. Then completely flatten ePTFE with a thickness of 5 μm on a doctor blade coater, pour in the resin solution for doctor blade coating. After completion, place it at 30 °C for 2 h to dry and obtain the elementary composite membrane;

[0048] (3) Preparation of the multi-layer anion exchange composite membrane:

[0049] Stack two elementary composite membranes layer by layer and flatten them on a hot press. Preheat at 100 °C for 10 min, then apply a pressure of 2 MPa, adjust the temperature to 100 °C and hold for 30 min to obtain a double-layer anion exchange composite membrane.

[0050] Example 2

[0051] This example provides a method for preparing a multi-layer anion exchange composite membrane, including the following steps:

[0052] (1) Preparation of polystyrene-modified ion exchange resin:

[0053] (1.1) Under a nitrogen atmosphere, dissolve 10 g of polystyrene particles in 150 ml of dichloromethane to obtain a 0.067 g / ml solution. Subsequently, add 8.20 g of 6-bromohexanoyl chloride and 7.68 g of anhydrous aluminum trichloride, and react at 25 °C for 15 h. After the reaction is completed, pour the reaction solution into an appropriate amount of ethanol to precipitate the product and wash it with ethanol multiple times. Filter and dry in vacuum at 30 °C to obtain product A;

[0054] (1.2) Dissolve 10 g of product A in 300 ml of dichloromethane to obtain a 0.033 g / ml solution. Add 65.17 g of trifluoroacetic acid and 9.97 g of triethylsilane, and stir at 25 °C for 48 h. After the reaction is completed, quench trifluoroacetic acid with 1 M KOH solution and wash with water until neutral. Pour the organic phase into ethanol to precipitate the product and wash it repeatedly with ethanol. Filter and dry in vacuum at 30 °C to obtain product B;

[0055] (1.3) Take 10 g of product B and dissolve it in 200 ml of NMP to obtain a 0.05 g / mL solution. Then add 13.13 g of quinuclidine and react at 60 °C for 24 h. After the reaction is completed, pour the reaction solution into ethyl acetate to precipitate the product and wash it repeatedly with ethyl acetate. Filter and dry in vacuum at 30 °C to obtain polystyrene-modified ion exchange resin;

[0056] (2) Preparation of the elementary composite membrane:

[0057] Dissolve the polystyrene-modified ion exchange resin in ethanol to obtain a 0.05 g / mL resin solution. Then completely flatten the ePTFE with a thickness of 5 μm on a doctor blade coater, pour in the resin solution for doctor blade coating, and after completion, place it at 30 °C for 2 h to dry to obtain the elementary composite membrane;

[0058] (3) Preparation of the multi-layer anion exchange composite membrane:

[0059] Stack two elementary composite membranes layer by layer and flatten them on a hot press. Preheat at 100 °C for 10 min, then apply a pressure of 2 MPa, adjust the temperature to 100 °C and hold for 30 min. After completion, take out to obtain a double-layer anion exchange composite membrane. Then repeat this step with the double-layer anion exchange composite membrane and one elementary composite membrane, and take out after completion to obtain a three-layer anion exchange composite membrane.

[0060] Example 3

[0061] This example provides a method for preparing a multi-layer anion exchange composite membrane, including the following steps:

[0062] (1) Preparation of polystyrene-modified ion exchange resin:

[0063] (1.1) Under a nitrogen atmosphere, dissolve 10 g of polystyrene particles in 150 ml of dichloromethane to obtain a 0.067 g / ml solution. Then add 8.20 g of 6-bromohexanoyl chloride and 7.68 g of anhydrous aluminum trichloride, and react at 25 °C for 15 h. After the reaction is completed, pour the reaction solution into an appropriate amount of ethanol to precipitate the product and wash it repeatedly with ethanol. Filter and dry in vacuum at 30 °C to obtain product A;

[0064] (1.2) Dissolve 10 g of product A in 300 ml of dichloromethane to obtain a 0.033 g / ml solution, add 65.17 g of trifluoroacetic acid and 9.97 g of triethylsilane, stir at 25 °C for 48 h. After the reaction is completed, quench trifluoroacetic acid with 1 M KOH solution and wash with water until neutral. Pour the organic phase into ethanol to precipitate the product and wash it repeatedly with ethanol. Filter and dry in vacuo at 30 °C to obtain product B;

[0065] (1.3) Take 10 g of product B and dissolve it in 200 ml of NMP to obtain a 0.05 g / mL solution, then add 13.13 g of quinuclidine, and react at 60 °C for 24 h. After the reaction is completed, pour the reaction solution into ethyl acetate to precipitate the product and wash it repeatedly with ethyl acetate. Filter and dry in vacuo at 30 °C to obtain polystyrene-modified ion exchange resin.

[0066] (2) Preparation of the elementary composite membrane:

[0067] Dissolve the polystyrene-modified ion exchange resin in ethanol to obtain a 0.05 g / mL resin solution. Then, completely flatten the ePTFE with a thickness of 5 μm on a doctor blade coater, pour in the resin solution for doctor blade coating. After completion, place it at 30 °C for 2 h to dry and obtain the elementary composite membrane.

[0068] (3) Preparation of the multi-layer anion exchange composite membrane:

[0069] Stack two elementary composite membranes layer by layer and flatten them on a hot press. Preheat at 100 °C for 10 min, then apply a pressure of 2 MPa, adjust the temperature to 100 °C and maintain for 30 min. After completion, take out to obtain a double-layer anion exchange composite membrane. Subsequently, repeat this step for two double-layer anion exchange composite membranes. After completion, take out to obtain a four-layer anion exchange composite membrane.

[0070] Example 4

[0071] This example provides a method for preparing a multi-layer anion exchange composite membrane, including the following steps:

[0072] (1) Preparation of polystyrene-modified ion exchange resin:

[0073] (1.1) Under a nitrogen atmosphere, dissolve 10 g of polystyrene particles in 150 ml of dichloromethane to obtain a 0.067 g / mL solution. Subsequently, add 12.30 g of 6-bromohexanoyl chloride and 10.24 g of anhydrous aluminum trichloride, and react at 25 °C for 15 h. After the reaction is completed, pour the reaction solution into ethanol and wash it repeatedly with ethanol. Filter and dry in vacuo at 30 °C to obtain product A;

[0074] (1.2) Dissolve 10 g of product A in 300 ml of dichloromethane to obtain a 0.033 g / mL solution. Add 54.20 g of trifluoroacetic acid and 8.29 g of triethylsilane, and stir at 25 °C for 48 h. After the reaction is completed, quench the trifluoroacetic acid with 1 M KOH solution and wash with water until neutral. Pour the organic phase into ethanol to precipitate the product and wash it repeatedly with ethanol. Filter and dry in vacuo at 30 °C to obtain product B;

[0075] (1.3) Take 10 g of product B and dissolve it in 200 ml of NMP to obtain a 0.05 g / mL solution. Then add 11.01 g of quinuclidine and react at 60 °C for 24 h. After the reaction is completed, pour the reaction solution into ethyl acetate to precipitate the product and wash it repeatedly with ethyl acetate. Filter and dry in vacuo at 30 °C to obtain polystyrene-modified ion exchange resin;

[0076] (2) Preparation of the elementary composite membrane:

[0077] Dissolve the polystyrene-modified ion exchange resin in ethanol to obtain a 0.05 g / mL resin solution. Then completely flatten the ePTFE with a thickness of 5 μm on a knife coater, pour in the resin solution for knife coating, and after completion, place it at 30 °C for 2 h to dry to obtain the elementary composite membrane;

[0078] (3) Preparation of the multilayer anion exchange membrane:

[0079] Stack two elementary composite membranes layer by layer and flatten them on a hot press. Preheat at 100 °C for 10 min, then apply a pressure of 2 MPa, adjust the temperature to 100 °C and keep it for 30 min. After completion, take it out to obtain a double-layer anion exchange composite membrane.

[0080] Example 5

[0081] This example provides a method for preparing a multilayer anion exchange composite membrane, including the following steps:

[0082] (1) Preparation of polystyrene-modified ion exchange resin:

[0083] (1.1) Under a nitrogen atmosphere, dissolve 10 g of polystyrene particles in 150 ml of dichloromethane to obtain a 0.067 g / mL solution. Subsequently, add 20.50 g of 6-bromohexanoyl chloride and 12.80 g of anhydrous aluminum trichloride, and react at 25 °C for 15 h. After the reaction is completed, pour the reaction solution into ethanol and wash it repeatedly with ethanol. Filter and dry in vacuo at 30 °C to obtain product A;

[0084] (1.2) Dissolve 10 g of product A in 300 ml of dichloromethane to obtain a 0.033 g / mL solution. Add 60.82 g of trifluoroacetic acid and 12.41 g of triethylsilane, and stir at 25 °C for 48 h. After the reaction is completed, quench trifluoroacetic acid with 2 M KOH solution and wash with water until neutral. Pour the organic phase into ethanol to precipitate the product and wash it repeatedly with ethanol. Filter and dry in vacuum at 30 °C to obtain product B;

[0085] (1.3) Take 10 g of product B and dissolve it in 200 ml of NMP to obtain a 0.05 g / mL solution. Then add 12.48 g of quinuclidine and react at 60 °C for 24 h. After the reaction is completed, pour the reaction solution into ethyl acetate to precipitate the product and wash it repeatedly with ethyl acetate. Collect the polystyrene-modified ion exchange resin by filtration and dry in vacuum at 30 °C;

[0086] (2) Preparation of the elementary composite membrane:

[0087] Dissolve the polystyrene-modified ion exchange resin in ethanol to obtain a 0.05 g / mL resin solution. Then completely flatten the ePTFE with a thickness of 5 μm on a doctor blade coater, pour in the resin solution for doctor blade coating, and after completion, place it at 30 °C for 2 h to dry to obtain the elementary composite membrane;

[0088] (3) Preparation of the multilayer anion exchange composite membrane:

[0089] Stack two elementary composite membranes layer by layer and flatten them on a hot press. Preheat at 100 °C for 10 min, then apply a pressure of 2 MPa, adjust the temperature to 100 °C and keep it for 30 min. After completion, take it out to obtain the double-layer anion exchange composite membrane.

[0090] Example 6

[0091] This example provides a method for preparing a multilayer anion exchange composite membrane, including the following steps:

[0092] (1) Preparation of the polystyrene-modified ion exchange resin:

[0093] (1.1) Under a nitrogen atmosphere, dissolve 10 g of polystyrene particles in 150 ml of dichloromethane to obtain a 0.067 g / mL solution. Then add 8.20 g of 6-bromohexanoyl chloride and 7.68 g of anhydrous aluminum trichloride, and react at 25 °C for 15 h. After the reaction is completed, pour the reaction solution into ethanol and wash it repeatedly with ethanol. Filter and dry in vacuum at 30 °C to obtain product A;

[0094] (1.2) Dissolve 10 g of product A in 300 ml of dichloromethane to obtain a 0.033 g / mL solution. Add 65.17 g of trifluoroacetic acid and 9.97 g of triethylsilane, and stir at 25 °C for 48 h. After the reaction is completed, quench trifluoroacetic acid with 1 M KOH solution and wash with water until neutral. Pour the organic phase into ethanol to precipitate the product and wash it with ethanol several times. Filter and dry in vacuo at 30 °C to obtain product B;

[0095] (1.3) Take 10 g of product B and dissolve it in 200 ml of NMP to obtain a 0.05 g / mL solution. Then add 11.8 g of trimethylamine-ethanol solution (the concentration of trimethylamine is 30 wt%), and react at 30 °C for 48 h. After the reaction is completed, pour the reaction solution into ethyl acetate to precipitate the product and wash it with ethyl acetate several times. Filter and dry in vacuo at 30 °C to obtain polystyrene-modified ion exchange resin;

[0096] (2) Preparation of the elementary composite membrane:

[0097] Dissolve the polystyrene-modified ion exchange resin in ethanol to obtain a 0.05 g / mL resin solution. Then completely flatten ePTFE with a thickness of 5 μm on a doctor blade coater, pour in the resin solution for doctor blading, and after completion, place it at 30 °C for 2 h to dry to obtain the elementary composite membrane;

[0098] (3) Preparation of the multilayer anion exchange composite membrane:

[0099] Stack two elementary composite membranes flat on a hot press, preheat at 100 °C for 10 min, then apply a pressure of 2 MPa, adjust the temperature to 100 °C and hold for 30 min. After completion, take it out to obtain a double-layer anion exchange composite membrane.

[0100] Comparative Example 1

[0101] (1) Preparation of the elementary composite membrane:

[0102] Completely flatten ePTFE with a thickness of 5 μm on a doctor blade coater, pour in a commercially available Alkymer anion exchange resin solution for doctor blading, and after completion, place it at 30 °C for 2 h to dry to obtain the elementary composite membrane;

[0103] (2) Preparation of hot press assembly, the steps are as follows:

[0104] Stack two elementary composite membranes flat on a hot press, preheat at 100 °C for 10 min, then apply a pressure of 2 MPa, adjust the temperature to 100 °C and hold for 30 min. After completion, take it out and find that a double-layer anion exchange composite membrane cannot be obtained.

[0105] As Figure 1The following is the NMR spectrum of the quinuclidine-modified polystyrene modified ion exchange resin in Example 1. The peak at 2.46 ppm represents the hydrogen atom on the α-carbon of the benzene ring grafted side chain, proving the successful grafting of the side chain. At the same time, the peaks at 3.09 ppm and 3.37 ppm represent the successful introduction of cations.

[0106] As Figure 2 The following is the optical photograph of the elementary composite membrane in Example 1. It can be seen that the elementary composite membrane was successfully cast.

[0107] As Figure 3 The following is the SEM image of the elementary composite membrane in Example 1, proving the compactness of the elementary composite membrane.

[0108] As Figure 4 The following water absorption rate graph shows that the multilayer anion exchange composite membranes prepared in Examples 1-3 and Example 6 all have excellent water absorption performance. At the same time, the composite membrane quaternized with quinuclidine has more excellent water absorption ability than the composite membrane quaternized with trimethylamine.

[0109] As Figure 5 The following is the mechanical property graph of the multilayer anion exchange composite membranes prepared in Examples 1-3, which can illustrate the layer-by-layer strengthening effect of the multilayer composite strategy. As the number of layers increases, the mechanical properties improve.

[0110] As Figure 6 The following is the NMR characterization graph of the trimethylamine-modified polystyrene modified ion exchange resin prepared in Example 6. It can be seen from the graph that the peak at 2.46 ppm represents the hydrogen atom on the α-carbon of the benzene ring grafted side chain, proving the successful grafting of the side chain. At the same time, the peaks at 3.04 ppm and 3.27 ppm represent the successful introduction of cations.

[0111] The above examples are only the preferred examples of the present invention and do not limit the implementation mode. The protection scope of the present invention should be subject to the scope defined by the claims. Based on the above description, other different forms of changes or modifications can be made. The obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for preparing a multi-layer anion exchange composite membrane, characterized in that, It includes the following steps: thermally pressing and assembling multiple elementary composite membranes to obtain the multilayer anion exchange composite membrane; the elementary composite membrane includes a base membrane and an ion exchange resin; the glass transition temperature of the ion exchange resin is 60 - 130 °C; the temperature of the thermocompression assembly is 80 - 140 °C.

2. The preparation method according to claim 1, characterized in that, The base membrane is at least one of ePTFE, ETFE, PVDF, PE, PP, and PEEK; the thickness of the base membrane is 3 - 30 μm.

3. The preparation method according to claim 1, characterized in that, The ion exchange resin is a polystyrene-modified ion exchange resin, and its chemical structure is shown in formula (I): In formula (I): x = 5 - 100, n = 2 - 10; R = One of the following.

4. The preparation method according to claim 3, characterized in that, The preparation method of the polystyrene-modified ion exchange resin includes the following steps: (1) Under a nitrogen atmosphere, dissolve polystyrene particles in dichloromethane, then add monomer 1 and anhydrous aluminum trichloride, and react at 25 °C for 12 - 24 h. After the reaction, precipitate the product, wash, filter, and dry to obtain product A; monomer 1 is shown in formula (Ⅱ): In formula (Ⅱ): m = 0 - 8, X is a halogen; (2) Dissolve product A in dichloromethane, add trifluoroacetic acid and triethylsilane, and stir at 15 - 25 °C for 48 h. After the reaction, quench trifluoroacetic acid with 1 - 3M KOH solution and wash to neutrality, precipitate the product, wash, filter, and dry to obtain product B; (3) Dissolve product B in an aprotic polar solvent, add monomer 2, and react at 25 - 80 °C for 12 - 48 h. After the reaction, precipitate the product, wash, filter, and dry to obtain the polystyrene-modified ion exchange resin; The monomer 2 is one of them.

5. The preparation method according to claim 3, characterized in that, In step (1), the concentration of polystyrene dissolved in dichloromethane is 0.05 - 0.1 g / mL, the molar ratio of monomer 1 to polystyrene is (0.05 - 2):1, and the molar ratio of anhydrous aluminum trichloride to polystyrene is (0.1 - 2):1; In step (2), the concentration of product A dissolved in dichloromethane is 0.02 - 0.1 g / mL, the molar ratio of trifluoroacetic acid to product A is (1 - 15):1, and the molar ratio of triethylsilane to product A is (1 - 5):1; In step (3), the concentration of product B dissolved in the aprotic polar solvent is 0.02 - 0.1 g / mL, the aprotic polar solvent is one of DMSO, NMP, DMF, and DMAc, and the molar ratio of monomer 2 to product B is (1 - 5):

1.

6. The preparation method according to claim 1, wherein The preparation method of the elementary composite membrane includes the following steps: Dissolve the polystyrene-modified ion exchange resin in ethanol to obtain a resin solution, scrape the resin solution onto the base membrane, and dry to obtain the elementary composite membrane; The concentration of the resin solution is 0.02 - 0.1 g / mL.

7. The preparation method according to claim 7, characterized in that, The drying temperature is 20 - 50 °C, and the drying time is 0.5 - 12 h.

8. The preparation method according to claim 1, characterized in that, The specific method of the hot pressing is: Stack and flatten the elementary composite membranes layer by layer on a hot press, preheat at 80 - 100 °C for 10 - 30 min, then apply a pressure of 2 - 10 MPa, adjust the temperature to 80 - 140 °C and maintain for 30 - 60 min to obtain the multilayer anion exchange composite membrane.

9. Use of the anion exchange composite membrane prepared by the preparation method according to any one of claims 1-8 in an anion exchange membrane fuel cell and in electrolyzed water.

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