Anion exchange membrane, preparation method thereof, application and electrolysis device

Abstract

This application relates to the field of electrolysis technology, and provides an anion exchange membrane, a preparation method thereof, an application thereof, and an electrolysis device. The anion exchange membrane includes a polymer main chain, and a plurality of side chains are grafted on the polymer main chain, and the side chains contain fluorine groups and phenyl groups. The anion exchange membrane of this application has high conductivity and good stability.

Description

Technical Field

[0001] The present application relates to the field of electrolysis technology, and particularly to an anion exchange membrane, a preparation method thereof, an application thereof, and an electrolysis device. Background Art

[0002] Hydrogen production by electrolyzing water has become an important way of hydrogen production due to its simple principle and high energy efficiency. Among them, the key to electrolyzing water lies in the electrolyte material used in the electrolytic cell, especially the performance of the membrane material directly affects the electrolysis efficiency and the hydrogen production. The anion exchange membrane (AEM) type electrolytic cell is a new type of electrolytic cell technology that has developed rapidly in recent years, combining the advantages of low cost of traditional alkaline electrolytic cells and high electrolysis efficiency of proton exchange membrane type electrolytic cells. In traditional technologies, quaternary ammonium salt type anion exchange membranes and polyarylpiperidine type anion exchange membranes are used. The quaternary ammonium salt type anion exchange membrane has problems such as poor ion conductivity, insufficient chemical stability, and poor compatibility at the membrane-electrode interface; the ion conductivity and alkali resistance of the polyarylpiperidine type anion exchange membrane still need to be improved. Therefore, how to improve the conductivity and stability of the anion exchange membrane has become an urgent technical problem to be solved at present. Summary of the Invention

[0003] Based on this, an embodiment of the present application provides an anion exchange membrane with high conductivity and good stability, a preparation method thereof, an application thereof, and an electrolysis device.

[0004] In a first aspect, the present application provides an anion exchange membrane, which includes a polymer main chain, and a plurality of side chains are grafted on the polymer main chain, and the side chains contain fluorine groups and phenyl groups.

[0005] In some embodiments, the polymer main chain includes at least one of polyarylpiperidine polymers, polyaryl isatin polymers, and polybenzimidazole polymers.

[0006] In some embodiments, the side chains include at least one of 2,4,5-trifluorobenzyl group, 2,3,6-trifluorobenzyl group, 3,4,5-trifluorobenzyl group, 4-fluoroethylphenyl group, 3,4-difluorobenzyl group, 2,4-difluorobenzyl group, and 2,6-difluorobenzyl group.

[0007] In some embodiments, the mass ratio of the polymer main chain to the side chains is 1:(0.07 - 0.3).

[0008] In a second aspect, the present application provides a preparation method of an anion exchange membrane, and the preparation method includes:

[0009] Mix the polymer backbone, grafting agent, and acid-binding agent to obtain a mixed solution. The grafting agent is grafted onto the polymer backbone to form side chains containing fluorine groups and phenyl groups, and a polymer material is prepared.

[0010] Dissolve the polymer material to form a casting solution, and coat the casting solution to obtain a precast film.

[0011] Perform ion exchange treatment on the precast film to prepare the anion exchange membrane.

[0012] In some embodiments, the mass ratio of the polymer backbone to the grafting agent is 1:(0.07 - 0.3).

[0013] In some embodiments, the mass ratio of the polymer backbone to the acid-binding agent is 1:(0.5 - 1).

[0014] In some embodiments, the grafting agent includes at least one of 2,4,5-trifluorobenzyl bromide, 2,3,6-trifluorobenzyl bromide, 3,4,5-trifluorobromobenzene, 4-fluorobromoethylbenzene, 3,4-difluorobromobenzene, 2,4-difluorobromobenzene, and 2,6-difluorobromobenzene.

[0015] In some embodiments, the acid-binding agent includes at least one of potassium carbonate, sodium hydride, sodium bicarbonate, trimethylamine, and sodium carbonate.

[0016] In some embodiments, the mass percentage concentration of the polymer material in the casting solution is 5% - 25%.

[0017] In some embodiments, the ion exchange treatment includes:

[0018] Perform ion exchange treatment on the precast film using an alkaline solution.

[0019] Optionally, the alkaline compounds contained in the alkaline solution include at least one of potassium hydroxide, sodium hydroxide, and calcium hydroxide.

[0020] In some embodiments, after the grafting agent is grafted onto the polymer backbone, the preparation method further includes: adding a haloalkane to perform a quaternization reaction on the polymer backbone.

[0021] Optionally, the mass ratio of the polymer backbone to the haloalkane is 1:(0.6 - 1).

[0022] Optionally, the haloalkane includes at least one of methyl iodide, ethyl iodide, and 2-iodopropane.

[0023] In some embodiments, the preparation method of the polymer backbone includes:

[0024] Mix the aromatic monomer and the ketone monomer to obtain a first solution;

[0025] Mix the first solution and an acidic catalyst to prepare a polymer backbone.

[0026] In some embodiments, the molar ratio of the aromatic monomer to the ketone monomer is 1 to 1.2:1.

[0027] In some embodiments, the aromatic monomer includes at least one of p-terphenyl, m-terphenyl, biphenyl, benzylidene and 9,9'-diphenylfluorene.

[0028] In some embodiments, the ketone monomer includes at least one of N-methyl-4-piperidone, isatin, 3-quinuclidinone, 1,1,1-trifluoroacetone and 2,2,2-trifluoroacetophenone.

[0029] In some embodiments, the acidic catalyst includes at least one of trifluoroacetic acid, trifluoromethanesulfonic acid, perfluoropropionic acid, pentafluoroethanesulfonic acid and heptafluorobutyric acid.

[0030] Optionally, the acidic catalyst includes trifluoroacetic acid and trifluoromethanesulfonic acid. Further optionally, the molar ratio of the trifluoroacetic acid to the ketone monomer is 1 to 1.5:1; the molar ratio of the trifluoromethanesulfonic acid to the ketone monomer is 9 to 12:1.

[0031] In a third aspect, the present application provides an application of the anion exchange membrane as described in the first aspect in the preparation of an electrolysis device.

[0032] In a fourth aspect, the present application provides an electrolysis device, which includes the anion exchange membrane as described in the first aspect and / or the anion exchange membrane prepared by the preparation method of the anion exchange membrane as described in the second aspect.

[0033] Compared with the traditional technology, the present application has at least the following beneficial effects:

[0034] The present application uses a side chain containing a fluorine group and a phenyl group to graft-modify the polymer backbone. This side chain has a large volume and high hydrophobicity, which can promote the aggregation of hydrophilic cationic groups, thereby promoting microphase separation, being beneficial to the rapid movement of ions, and improving the conductivity of the anion exchange membrane. In addition, the introduction of the hydrophobic large-volume side chain in the present application helps to inhibit the excessive swelling and performance degradation of the anion exchange membrane during use, and improves the chemical stability of the membrane. Description of the Drawings

[0035] Figure 1 It is the FT-IR spectrum of the polymer backbone prepared in Example 3 and Comparative Example 1 of the present application;

[0036] Figure 2Contact angle diagrams of the anion exchange membranes prepared in Example 3 of this application and Comparative Example 1 with water;

[0037] Figure 3 Mechanical strength comparison diagrams of the anion exchange membranes prepared in Examples 1-3 of this application and Comparative Example 1;

[0038] Figure 4 Polarization curve diagrams of alkaline electrolyzed water of the anion exchange membranes in Example 3 of this application and Comparative Example 1;

[0039] Figure 5 Microscopic morphology comparison diagrams of the anion exchange membranes in Example 3 of this application and Comparative Example 1. Detailed implementation manners

[0040] The following combines the implementation manners and examples to further elaborate on this application in detail. These implementation manners and examples are only used to illustrate this application and not to limit the scope of this application. The purpose of providing these implementation manners and examples is to make the understanding of the disclosed content of this application more thorough and comprehensive. It should also be understood that this application can be implemented in many different forms and is not limited to the implementation manners and examples described herein. Those skilled in the art can make various changes or modifications without departing from the connotation of this application, and the equivalent forms obtained also fall within the protection scope of this application. In addition, in the following description, a large number of specific details are given to provide a more thorough understanding of this application. It should be understood that this application can be implemented without one or more of these details.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application in this specification are only for the purpose of describing specific examples and are not intended to limit this application.

[0042] In this application, "optionally", "optional", "option" mean optional, that is, it refers to either of the two parallel options of "having" or "not having". If the term "optional" appears multiple times in a technical solution, without special instructions and without contradictions or mutual constraints, each "optional" is independent of each other.

[0043] In this application, in "the first aspect", "the second aspect", etc., the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0044] In this application, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0045] In this application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the selectable numerical values within this numerical interval is regarded as continuous, and it includes the two numerical endpoints of this numerical interval (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within this numerical interval, it includes the two endpoint integers of this numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all sub-ranges subsumed therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" is allowed to broadly include quantitative intervals such as a percentage interval, a ratio interval, a ratio value interval, etc.

[0046] All the documents mentioned in this application are cited in this application as references, just as if each document is cited separately as a reference. Unless it conflicts with the application purpose and / or technical solution of this application, the cited documents involved in this application are cited for all contents and all purposes. When this application involves cited documents, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited together. When this application involves cited documents, the examples and preferred ways of the relevant technical features cited can also be incorporated as references into this application, but only to the extent that this application can be implemented. It should be understood that when the cited content conflicts with the description in this application, this application shall prevail or be amended adaptively according to the description in this application.

[0047] In the traditional technology, in order to improve the ionic conductivity of the anion exchange membrane, a side chain structure with multiple hydrophilic cations is introduced into the polymer main chain to increase the local ionic group density, thereby promoting microphase separation and improving the ionic conductivity. However, a higher ion exchange capacity will cause a significant increase in the water absorption rate and swelling rate of the anion exchange membrane, resulting in a decrease in the dimensional stability of the membrane, and further affecting the overall service life of the anion exchange membrane.

[0048] In the first aspect of this application, an anion exchange membrane is provided. The anion exchange membrane includes a polymer main chain, and a plurality of side chains are grafted on the polymer main chain, and the side chains contain fluorine groups and phenyl groups.

[0049] In this application, a side chain containing a fluorine group and a phenyl group is used to graft-modify the polymer backbone. This side chain has a large volume and high hydrophobicity, which can promote the aggregation of hydrophilic cationic groups, thereby promoting microphase separation, facilitating the rapid movement of ions, and improving the conductivity of the anion exchange membrane. In addition, the introduction of the hydrophobic large-volume side chain in this application helps to inhibit the excessive swelling and performance degradation of the anion exchange membrane during use, and improves the chemical stability of the membrane.

[0050] In some embodiments, the polymer backbone includes at least one of polyarylpiperidine polymers, polyaryl isatin polymers, and polybenzimidazole polymers. Optionally, the polymer backbone includes a quaternized polyarylpiperidine polymer. In this application, a quaternized polyarylpiperidine polymer is used as the polymer backbone and cooperates with a side chain containing a fluorine group and a phenyl group, having good anti-swelling properties and good microphase separation, thereby being able to improve the ionic conductivity and alkali resistance stability of the anion exchange membrane.

[0051] It can be understood that other modifying groups can also be grafted onto the polymer backbone in this application to modify the polymer backbone, thereby improving the performance of the anion exchange membrane. For example, at least part of the piperidine groups in the polymer backbone are quaternized and modified with iodomethane.

[0052] In some embodiments, the side chain includes at least one of 2,4,5-trifluorobenzyl group, 2,3,6-trifluorobenzyl group, 3,4,5-trifluorobenzyl group, 4-fluoroethylphenyl group, 3,4-difluorobenzyl group, 2,4-difluorobenzyl group, and 2,6-difluorobenzyl group.

[0053] In some embodiments, the mass ratio of the polymer backbone to the side chain is 1:(0.07 - 0.3), and for example, it can be 1:0.07, 1:0.10, 1:0.13, 1:0.16, 1:0.19, 1:0.22, 1:0.25, 1:0.28, or 1:0.30.

[0054] In the second aspect of this application, a method for preparing an anion exchange membrane is provided. The preparation method includes:

[0055] Mixing a polymer backbone, a grafting agent, and an acid-binding agent to obtain a mixed solution. The grafting agent is grafted onto the polymer backbone to form a side chain containing a fluorine group and a phenyl group, and a polymer material is prepared;

[0056] Dissolving the polymer material to form a casting solution, and coating the casting solution to obtain a precast film;

[0057] Performing ion exchange treatment on the precast film to prepare the anion exchange membrane.

[0058] The anion exchange membrane is prepared as above, with side chains grafted onto the polymer backbone. The preparation method is simple, and the prepared anion exchange membrane has high ionic conductivity and good dimensional stability. Specifically, in this application, side chains containing fluoro groups and phenyl groups are used to graft and modify the polymer backbone. These side chains are relatively large in volume and highly hydrophobic, which can promote the aggregation of hydrophilic cationic groups, thereby promoting microphase separation and facilitating the rapid movement of ions, improving the conductivity of the anion exchange membrane. In addition, the introduction of the hydrophobic large-volume side chains in this application helps to inhibit the excessive swelling and performance degradation of the anion exchange membrane during use, improving the chemical stability of the membrane.

[0059] It can be understood that other modifying groups can also be grafted onto the polymer backbone in this application to modify the polymer backbone, thereby improving the performance of the anion exchange membrane. For example, part of the polymer backbone is iodomethanated.

[0060] In some embodiments, the mass ratio of the polymer backbone to the grafting agent is 1:(0.07 - 0.3), and can be, for example, 1:0.07, 1:0.10, 1:0.13, 1:0.16, 1:0.19, 1:0.22, 1:0.25, 1:0.28, or 1:0.30.

[0061] In some embodiments, the mass ratio of the polymer backbone to the acid-binding agent is 1:(0.5 - 1), and can be, for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, or 1:1.0.

[0062] In some embodiments, the grafting agent includes at least one of 2,4,5-trifluorobenzyl bromide, 2,3,6-trifluorobenzyl bromide, 3,4,5-trifluorobromobenzene, 4-fluorobromoethylbenzene, 3,4-difluorobromobenzene, 2,4-difluorobromobenzene, and 2,6-difluorobromobenzene.

[0063] In some embodiments, the acid-binding agent includes at least one of potassium carbonate, sodium hydride, sodium bicarbonate, trimethylamine, and sodium carbonate.

[0064] In some embodiments, the mass percentage concentration of the polymer material in the casting solution is 5% - 25%, and can be, for example, 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, or 25%.

[0065] In some embodiments, the ion exchange treatment includes:

[0066] The precast film is subjected to ion exchange treatment with an alkali solution.

[0067] Optionally, the basic compounds contained in the alkali solution include at least one of potassium hydroxide, sodium hydroxide, and calcium hydroxide.

[0068] In some embodiments, after the grafting agent is grafted onto the polymer backbone, the preparation method further includes: adding a halogenated alkane to conduct a quaternization reaction on the polymer backbone.

[0069] Optionally, the mass ratio of the polymer backbone to the halogenated alkane is 1:(0.6 - 1), for example, it can be 1:0.6, 1:0.7, 1:0.8, 1:0.9, or 1:1.0.

[0070] Optionally, the halogenated alkane includes at least one of methyl iodide, ethyl iodide, and 2 - iodopropane.

[0071] In some embodiments, the preparation process of the polymer material includes the following steps:

[0072] Adding a grafting agent and an acid - binding agent to a solution containing a polymer backbone to obtain a mixed solution. After reacting for a period of time, adding a halogenated alkane to the mixed solution. After the quaternization reaction, adding a first precipitating agent, washing the precipitate, and performing vacuum drying to obtain the polymer material.

[0073] In some embodiments, the solvent contained in the solution containing the polymer backbone includes at least one of dimethyl sulfoxide, N - methylpyrrolidone, N,N - dimethylformamide, and N,N - dimethylacetamide.

[0074] In some embodiments, adding a grafting agent and an acid - binding agent to a solution containing a polymer backbone to obtain a mixed solution, and the reaction time is 24h - 48h.

[0075] In some embodiments, the temperature of the quaternization is 30°C - 40°C, the environment is light - proof, and the time is 24h - 48h.

[0076] In some embodiments, the first precipitating agent includes at least one of ethyl acetate, acetone, and ether.

[0077] In some embodiments, the vacuum drying temperature of the polymer material is 60°C - 100°C, and the time is 24h - 36h.

[0078] In some embodiments, the preparation method of the polymer backbone includes:

[0079] Mixing an aromatic monomer and a ketone monomer to obtain a first solution;

[0080] Mixing the first solution and an acidic catalyst to prepare a polymer backbone.

[0081] In some embodiments, the molar ratio of the aromatic monomer to the ketone monomer is 1 - 1.2:1, for example, it can be 1.05:1, 1.10:1, 1.15:1, or 1.20:1.

[0082] In some embodiments, the aromatic monomer includes at least one of p-terphenyl, m-terphenyl, biphenyl, benzylidene, and 9,9'-diphenylfluorene.

[0083] In some embodiments, the ketone monomer includes at least one of N-methyl-4-piperidone, isatin, 3-quinuclidinone, 1,1,1-trifluoroacetone, and 2,2,2-trifluoroacetophenone.

[0084] In some embodiments, the acidic catalyst includes at least one of trifluoroacetic acid, trifluoromethanesulfonic acid, perfluoropropionic acid, pentafluoroethanesulfonic acid, and heptafluorobutyric acid.

[0085] Optionally, the acidic catalyst includes trifluoroacetic acid and trifluoromethanesulfonic acid. Further optionally, the molar ratio of trifluoroacetic acid to the ketone monomer is 1 to 1.5:1; the molar ratio of trifluoromethanesulfonic acid to the ketone monomer is 9 to 12:1.

[0086] In some embodiments, the solvent contained in the first solution includes at least one of dichloromethane, trifluoroacetic acid, and trifluoromethanesulfonic acid.

[0087] In some embodiments, after mixing the first solution and the acidic catalyst, a second precipitant is added after reacting for a period of time, and the polymer backbone is precipitated. Optionally, the polymer backbone is also washed and vacuum dried. Optionally, the reaction time is 6 h to 8 h. Optionally, the second precipitant includes at least one of anhydrous methanol, anhydrous ethanol, potassium hydroxide solution, and sodium hydroxide solution. Optionally, the temperature of the vacuum drying is 30°C to 100°C, and the time is 24 h to 36 h.

[0088] Exemplarily, a method for preparing the above anion exchange membrane is provided, including the following steps:

[0089] (1) Polymer backbone

[0090] The aromatic monomer and the ketone monomer are mixed in a molar ratio of 1 to 1.2:1 to obtain a first solution; an acidic catalyst is added to the first solution, and after reacting for 6 to 8 h, a second precipitant is added, and the precipitate is washed to neutrality and then vacuum dried at 30°C to 100°C for 24 h to 36 h to obtain the polymer backbone.

[0091] (2) Preformed membrane

[0092] The polymer backbone is dissolved, and then a grafting agent and an acid-binding agent are added, and the reaction is carried out for 24 h to 48 h; then an alkyl halide is added, and the quaternization reaction is carried out for 24 h to 48 h in the dark at 30°C to 40°C, and then a first precipitant is added. The precipitate is washed with deionized water multiple times and then vacuum dried at 60°C to 100°C for 24 h to 36 h to obtain the polymer material;

[0093] The polymer material is dissolved to form a solution with a mass percentage concentration of 5% - 25% to obtain a casting solution. The casting solution is coated to form a film, and a prefabricated film is obtained after drying at 60°C - 100°C for 24 h - 36 h.

[0094] (3)Ion treatment

[0095] The prefabricated film is subjected to ion exchange treatment with an alkali solution to prepare the anion exchange membrane.

[0096] The third aspect of the present application provides an application of the anion exchange membrane as described in the first aspect in the preparation of an electrolysis device.

[0097] The fourth aspect of the present application provides an electrolysis device, which includes the anion exchange membrane as described in the first aspect and / or the anion exchange membrane prepared by the preparation method of the anion exchange membrane as described in the second aspect.

[0098] In some embodiments, the electrolysis device includes a cathode, an anode, an anion exchange membrane, and an electrolytic cell filled with an electrolyte solution. The cathode, the anode, and the anion exchange membrane are respectively arranged in the electrolytic cell, and the anion exchange membrane is arranged between the cathode and the anode.

[0099] The embodiments of the present application will be described in detail below. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. For the experimental methods without specific conditions in the following embodiments, the guidance given in the present application is preferably referred to, and it can also be carried out according to the experimental manuals or conventional conditions in the art, or according to the conditions recommended by the manufacturers, or referring to the experimental methods known in the art.

[0100] Example 1

[0101] (1)Polymer main chain

[0102] Under ice bath conditions, 4.6 g of p-terphenyl and 2.5 mL of N-methyl-4-piperidone are added to 10 mL of dichloromethane and mixed; then, a mixed solution of 1.5 mL of trifluoroacetic acid and 16 mL of trifluoromethanesulfonic acid is added dropwise, and the reaction is continued for 6 h. The mixture is poured into anhydrous methanol for precipitation to obtain the polymer main chain; finally, the polymer main chain is washed repeatedly with deionized water until the pH is neutral, and dried in vacuo at 60°C for 24 h to obtain the polymer main chain.

[0103] (2)Prefabricated film

[0104] Weigh 1 g of the polymer backbone obtained in step (1) and dissolve it in 10 mL of NMP and 10 mL of DMSO. Then, add 0.04 mL of 2,4,5-trifluorobenzyl bromide to the reaction system, and add 0.62 g of potassium carbonate as an acid-binding agent and react for 24 h. Then, add 0.38 mL of methyl iodide to the reaction system and react in the dark at 30 °C for 24 h. Finally, pour the reaction solution into ethyl acetate for precipitation, wash it with deionized water, and then dry it under vacuum at 80 °C for 24 h to obtain the polymer material;

[0105] Weigh 0.5 g of the above polymer material and dissolve it in 10 mL of DMSO. After centrifuging to remove impurities, cast the casting solution on a glass plate and dry it at 60 °C for 24 h to form a film, obtaining a precast film.

[0106] (3) Ion treatment

[0107] Perform ion exchange treatment on the precast film with a 1 mol / L KOH solution to prepare the anion exchange membrane.

[0108] Example 2

[0109] (1) Polymer backbone

[0110] Under ice bath conditions, add 4.6 g of p-terphenyl and 2.5 mL of N-methyl-4-piperidone to 10 mL of dichloromethane and mix. Then, dropwise add a mixed solution of 1.8 mL of trifluoroacetic acid and 18 mL of trifluoromethanesulfonic acid, continue to react for 7 h, pour it into anhydrous methanol for precipitation to obtain the polymer backbone. Finally, wash the polymer backbone repeatedly with deionized water until the pH is neutral, and dry it under vacuum at 70 °C for 36 h to obtain the polymer backbone.

[0111] (2) Precast film

[0112] Weigh 1 g of the polymer backbone obtained in step (1) and dissolve it in 10 mL of NMP and 10 mL of DMSO. Then, add 0.04 mL of 2,4,5-trifluorobenzyl bromide to the reaction system, and add 0.65 g of potassium carbonate as an acid-binding agent and react for 36 h. Then, add 0.4 mL of methyl iodide to the reaction system and react in the dark at 35 °C for 36 h. Finally, pour the reaction solution into ethyl acetate for precipitation, wash it with deionized water, and then dry it under vacuum at 80 °C for 24 h to obtain the polymer material;

[0113] Weigh 0.5 g of the above polymer material and dissolve it in 10 mL of DMSO. After centrifuging to remove impurities, cast the casting solution on a glass plate and dry it at 70 °C for 36 h to form a film, obtaining a precast film.

[0114] (3) Ion treatment

[0115] The prepared membrane was subjected to ion exchange treatment with a 1 mol / L KOH solution to obtain the anion exchange membrane.

[0116] Example 3

[0117] (1) Polymer backbone

[0118] Under ice bath conditions, 4.6 g of p-terphenyl and 2.5 mL of N-methyl-4-piperidone were added to 10 mL of dichloromethane and mixed; then, a mixed solution of 2 mL of trifluoroacetic acid and 20 mL of trifluoromethanesulfonic acid was added dropwise, and the reaction was continued for 8 h. The reaction mixture was poured into anhydrous methanol to precipitate the polymer backbone; finally, the polymer backbone was washed repeatedly with deionized water until the pH was neutral, and then dried in vacuo at 100 °C for 36 h to obtain the polymer backbone.

[0119] (2) Prepared membrane

[0120] 1 g of the polymer backbone obtained in step (1) was weighed and dissolved in 10 mL of NMP and 10 mL of DMSO. Then, 0.08 mL of 2,4,5-trifluorobenzyl bromide was added to the reaction system, and 0.68 g of potassium carbonate was added as an acid-binding agent and reacted for 36 h; then, 0.6 mL of iodomethane was added to the reaction system, and the reaction was carried out in the dark at 40 °C for 30 h; finally, the reaction solution was poured into ether to precipitate, washed with deionized water, and dried in vacuo at 80 °C for 24 h to obtain a polymer material, the FT-IR spectrum of which is as Figure 1 shown;

[0121] 0.5 g of the above polymer material was weighed and dissolved in 10 mL of DMSO. After centrifuging to remove impurities, the casting solution was cast on a glass plate and dried at 100 °C for 30 h to form a film, obtaining the prepared membrane.

[0122] (3) Ion treatment

[0123] The prepared membrane was subjected to ion exchange treatment with a 1 mol / L KOH solution to obtain the anion exchange membrane.

[0124] Example 4

[0125] The anion exchange membrane was prepared according to the method of Example 3, except that the mass ratio of the polymer backbone to the grafting agent was 1:0.02.

[0126] Example 5

[0127] The anion exchange membrane was prepared according to the method of Example 3, except that the mass ratio of the polymer backbone to the grafting agent was 1:0.5.

[0128] Comparative Example 1

[0129] (1) Polymer backbone

[0130] Under ice bath conditions, 4.6 g of p-terphenyl and 2.5 mL of N-methyl-4-piperidone were added to 10 mL of dichloromethane and mixed; then, a mixed solution of 1.7 mL of trifluoroacetic acid and 17 mL of trifluoromethanesulfonic acid was added dropwise, and the reaction was continued for 6 h. The reaction mixture was poured into anhydrous methanol to precipitate the polymer backbone; finally, the polymer backbone was washed repeatedly with deionized water until the pH was neutral, and then dried in vacuo at 70 °C for 24 h to obtain the polymer backbone.

[0131] (2)Precast film

[0132] Weigh 1 g of the polymer backbone obtained in step (1) and dissolve it in 10 mL of NMP and 10 mL of DMSO. Then, add 0.62 g of potassium carbonate as an acid-binding agent and react for 24 h; then, add 0.6 mL of iodomethane to the reaction system and react in the dark at 35 °C for 24 h; finally, pour the reaction solution into ether to precipitate, wash it with deionized water, and dry it in vacuo at 80 °C for 24 h to obtain the polymer material, and its FT-IR spectrum is as Figure 1 shown;

[0133] Weigh 0.5 g of the above polymer material and dissolve it in 10 mL of DMSO. After centrifuging to remove impurities, the casting solution was cast on a glass plate and dried at 80 °C for 24 h to form a film, obtaining the precast film.

[0134] (3)Ion treatment

[0135] The precast film was subjected to ion exchange treatment with 1 mol / L KOH solution to prepare the anion exchange membrane.

[0136] Comparative Example 2

[0137] The anion exchange membrane was prepared according to the method of Example 3, except that the grafting agent was replaced with 0.06 mL of 2-iodo-1,1,1-trifluoroethane.

[0138] Comparative Example 3

[0139] The anion exchange membrane was prepared according to the method of Example 3, except that the grafting agent was replaced with 0.083 mL of β-bromoethylbenzene.

[0140] The anion exchange membranes prepared in the above examples and comparative examples were subjected to performance testing, and the testing methods included:

[0141] Impedance test: At room temperature (25 °C), the impedance of the anion exchange membrane was detected by the p-EIS method using an electrochemical workstation (gamry).

[0142] Conductivity: The resistance value at room temperature (25 °C) was measured by the p-EIS impedance method, and the conductivity of the membrane was calculated through the formula σ = L / RA, where R is the impedance value of the membrane, L is the thickness of the membrane, and A is the effective area of the membrane;

[0143] Contact angle: The contact angle between the anion exchange membrane and water was measured using a contact angle measuring instrument (JY-PHcAngleTester). Among them, Figure 2 is the contact angle diagram of Example 3 and Comparative Example 1 with water;

[0144] Mechanical strength: A tensile machine (LABRD-V2.9) was used to detect the tensile strength and elongation at break of the wet membrane. Figure 3 is the mechanical strength comparison diagram of Example 1, Example 2, Example 3 and Comparative Example 1;

[0145] Current density: Under the conditions of 55 °C, without cathode and anode catalysts, and at a voltage of 2 V, an electrolyzed water test system was used to test the current density. Figure 4 is the polarization curve diagram of alkaline electrolyzed water in Example 3 and Comparative Example 1.

[0146] Microstructural characterization: A transmission electron microscope (JEOLJEM-2000EX) was used to determine the microstructure of the anion exchange membrane. The microtopography comparison of the anion exchange membranes in Example 3 and Comparative Example 1 Figure 5 is shown.

[0147] The test results are shown in Table 1.

[0148] Table 1

[0149]

[0150] It can be seen from the above table that:

[0151] (1) Comparing Example 3 with Examples 4-5, it can be seen that by controlling the addition amount of the grafting agent in this application, the anion exchange membrane has higher ionic conductivity, better tensile strength, and better electrolyzed water performance. If the addition amount of the grafting agent is relatively low, it may be due to insufficient driving force of the hydrophobic side chain for the aggregation of hydrophilic cationic groups, resulting in problems such as the inability to form ion clusters and the inability to improve ionic conductivity. If the addition amount of the grafting agent is relatively high, it may be due to a large reduction in the ion exchange capacity in the membrane, resulting in problems such as a decrease in the proportion of hydrophilic domains and low ionic conductivity.

[0152] (2) Comparing Example 3 with Comparative Example 1, Comparative Example 2 and Comparative Example 3, it can be seen that in combination with Figure 5Compared with the microscopic morphology of Comparative Example 1, the microphase separation in Example 3 is more obvious, with lower impedance and higher ionic conductivity. In this application, by grafting side chains containing F element and phenyl group, it can be seen from the mechanical property data that with the increase of the introduction amount of hydrophobic large-volume side chains, its mechanical property has been significantly improved. With the increase of the introduction amount of hydrophobic large-volume side chains, the battery performance has been improved, which indicates that the introduction of hydrophobic large-volume side chains promotes the microphase separation in the membrane to a certain extent, improves the conductivity, and thus improves the battery performance.

[0153] In summary, in this application, the main chain of the polymer is grafted and modified with side chains containing fluoro group and phenyl group. The side chain has a large volume and high hydrophobicity, which can promote the aggregation of hydrophilic cationic groups, thus promoting microphase separation, facilitating the rapid movement of ions, and improving the conductivity of the anion exchange membrane. In addition, the introduction of the hydrophobic large-volume side chain in this application helps to inhibit the excessive swelling and performance degradation of the anion exchange membrane during use, and improves the chemical stability of the membrane.

[0154] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0155] The above-described embodiments only represent several implementation manners of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the application. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of this application should be subject to the appended claims.

Claims

1. An anion exchange membrane, characterized in that, The anion exchange membrane includes a polymer backbone, and a plurality of side chains are grafted onto the polymer backbone, and the side chains contain fluoro groups and phenyl groups; The polymer backbone includes at least one of polyarylpiperidine polymers, polyaryl isatin polymers, and polybenzimidazole polymers. The side chains include at least one of 2,4,5-trifluorobenzyl groups, 2,3,6-trifluorobenzyl groups, 3,4,5-trifluorobenzyl groups, 4-fluoroethylphenyl groups, 3,4-difluorobenzyl groups, 2,4-difluorobenzyl groups, and 2,6-difluorobenzyl groups. The mass ratio of the polymer backbone to the side chains is 1:(0.07 - 0.3); The preparation method of the anion exchange membrane includes: Mixing a polymer backbone, a grafting agent, and an acid-binding agent to obtain a mixed solution. The grafting agent is grafted onto the polymer backbone to form side chains containing fluoro groups and phenyl groups, and then an alkyl halide is added to conduct a quaternization reaction on the polymer backbone to prepare a polymer material. The mass ratio of the polymer backbone to the grafting agent is 1:(0.07 - 0.3). The polymer backbone includes at least one of polyarylpiperidine polymers, polyaryl isatin polymers, and polybenzimidazole polymers. The grafting agent includes at least one of 2,4,5-trifluorobenzyl bromide, 2,3,6-trifluorobenzyl bromide, 3,4,5-trifluorobenzyl bromide, 4-fluorobromoethylbenzene, 3,4-difluorobenzyl bromide, 2,4-difluorobenzyl bromide, and 2,6-difluorobenzyl bromide; Dissolving the polymer material to form a casting solution, and coating the casting solution to obtain a prefabricated membrane; Performing an ion exchange treatment on the prefabricated membrane to prepare the anion exchange membrane.

2. A method for preparing an anion exchange membrane, characterized in that, The preparation method includes: Mixing a polymer backbone, a grafting agent, and an acid-binding agent to obtain a mixed solution. The grafting agent is grafted onto the polymer backbone to form side chains containing fluoro groups and phenyl groups, and then an alkyl halide is added to conduct a quaternization reaction on the polymer backbone to prepare a polymer material. The mass ratio of the polymer backbone to the grafting agent is 1:(0.07 - 0.3). The polymer backbone includes at least one of polyarylpiperidine polymers, polyaryl isatin polymers, and polybenzimidazole polymers. The grafting agent includes at least one of 2,4,5-trifluorobenzyl bromide, 2,3,6-trifluorobenzyl bromide, 3,4,5-trifluorobenzyl bromide, 4-fluorobromoethylbenzene, 3,4-difluorobenzyl bromide, 2,4-difluorobenzyl bromide, and 2,6-difluorobenzyl bromide; Dissolving the polymer material to form a casting solution, and coating the casting solution to obtain a prefabricated membrane; Performing an ion exchange treatment on the prefabricated membrane to prepare the anion exchange membrane.

3. The preparation method of the anion exchange membrane according to claim 2, characterized in that The preparation method of the anion exchange membrane satisfies at least one of the following conditions: (1) The mass ratio of the polymer backbone to the acid-binding agent is 1:(0.5 - 1); (2) The acid-binding agent includes at least one of potassium carbonate, sodium hydride, sodium bicarbonate, trimethylamine, and sodium carbonate; (3) The mass percentage concentration of the polymer material in the casting solution is 5% - 25%.

4. The preparation method of the anion exchange membrane according to claim 2, characterized in that, The ion exchange treatment includes: The prefabricated membrane is subjected to ion exchange treatment with an alkaline solution.

5. The method for preparing an anion exchange membrane according to claim 4, wherein The alkaline compounds contained in the alkaline solution include at least one of potassium hydroxide, sodium hydroxide, and calcium hydroxide.

6. The preparation method of the anion exchange membrane according to claim 3, characterized in that, The mass ratio of the polymer main chain to the haloalkane is 1:(0.6 - 1).

7. The preparation method of the anion exchange membrane according to claim 3, characterized in that, The haloalkane includes at least one of methyl iodide, ethyl iodide, and 2-iodopropane.

8. The method for preparing an anion exchange membrane according to any one of claims 2-7, characterized in that, The preparation method of the polymer main chain includes: Mixing an aromatic monomer and a ketone monomer to obtain a first solution; Mixing the first solution and an acidic catalyst to prepare a polymer main chain.

9. The method for preparing an anion exchange membrane according to claim 8, wherein, The preparation method of the polymer main chain satisfies at least one of the following conditions: (1) The molar ratio of the aromatic monomer to the ketone monomer is 1 - 1.2:1; (2) The aromatic monomer includes at least one of p-terphenyl, m-terphenyl, biphenyl, benzylidene, and 9,9'-diphenylfluorene; (3) The ketone monomer includes at least one of N-methyl-4-piperidone, isatin, 3-quinuclidinone, 1,1,1-trifluoroacetone, and 2,2,2-trifluorophenylethanone; (4) The acidic catalyst includes at least one of trifluoroacetic acid, trifluoromethanesulfonic acid, perfluoropropionic acid, pentafluoroethanesulfonic acid, and heptafluorobutyric acid.

10. The preparation method of the anion exchange membrane according to claim 9, characterized in that, The acidic catalyst includes trifluoroacetic acid and trifluoromethanesulfonic acid.

11. The method for preparing an anion exchange membrane according to claim 10, characterized in that, The molar ratio of the trifluoroacetic acid to the ketone monomer is 1 - 1.5:1; the molar ratio of the trifluoromethanesulfonic acid to the ketone monomer is 9 - 12:

1.

12. Use of the anion exchange membrane according to claim 1 in the preparation of an electrolysis device.

13. An electrolysis device, characterized in that, The electrolysis device includes the anion exchange membrane according to claim 1 and / or an anion exchange membrane prepared by the preparation method of the anion exchange membrane according to any one of claims 2 - 11.

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