Ion-conducting polymer, preparation method of ion-conducting cross-linked substance, anion-exchange membrane and application of anion-exchange membrane

Abstract

The invention provides an ion conduction polymer, a preparation method of an ion conduction cross-linked substance, an anion exchange membrane and application thereof, and belongs to the technical field of electrochemistry. The anion-exchange membrane is prepared by regulating and controlling groups in side chains connected with a main chain skeleton in the ion-conducting polymer and crosslinking the ion-conducting polymer, so that the ion conductivity of the anion-exchange membrane can be improved, and the anion-exchange membrane has relatively good electrochemical performance; the swelling rate of the anion exchange membrane can be reduced, the alkali stability of the anion exchange membrane can be improved, the anion exchange membrane has long service life, and the application range of the anion exchange membrane can be widened to a great extent.

Description

Technical Field

[0001] This application relates to the field of electrochemical technology, and more specifically, to an ion-conducting polymer, a method for preparing an ion-conducting crosslinker, an anion exchange membrane, and its applications. Background Technology

[0002] Anion exchange membranes are a type of polymer membrane containing basic active groups and exhibiting selective permeability to anions; they are also known as ion-selective permeable membranes. Anion exchange membranes play a crucial role in electrochemical technologies such as electrolysis, electrodialysis, fuel cells, and flow batteries.

[0003] The application of anion exchange membranes is mainly affected by their electrochemical performance and lifespan; among which, the lifespan of anion exchange membranes is primarily influenced by their swelling ratio. However, existing anion exchange membranes cannot simultaneously possess both good electrochemical performance (e.g., low ionic conductivity) and a low swelling ratio, making it impossible for them to meet the increasingly higher requirements of technological advancements and significantly limiting their application. Summary of the Invention

[0004] The purpose of this application is to provide an ion-conducting polymer, a method for preparing an ion-conducting crosslinker, an anion exchange membrane, and its application, which aims to improve the swelling and electrochemical performance of existing anion exchange membranes, so that the anion exchange membrane has both better electrochemical performance and lower swelling rate.

[0005] In a first aspect, this application provides an ion-conducting polymer, the structural formula of which is as follows:

[0006] Where m≥0, n≥2, z is 0 or 1, and m and z are not both 0; R1 is a group containing a phenyl group; R2 is a quaternary ammonium group; X - It is an anion.

[0007] This application modifies the groups in the side chains connected to the main chain backbone of the ion-conducting polymer, and uses the crosslinking of this ion-conducting polymer to prepare anion exchange membranes. This not only improves the ionic conductivity of the anion exchange membrane, giving it better electrochemical properties, but also reduces the swelling rate and improves the alkali stability of the anion exchange membrane, resulting in a longer service life and greatly expanding the application range of anion exchange membranes.

[0008] In conjunction with the first aspect, in an optional embodiment of this application, 10 ≥ m ≥ 0; or / and, z = 1.

[0009] The above technical solutions are beneficial for further improving the ionic conductivity of anion exchange membranes and reducing their swelling rate, thereby further broadening the application range of anion exchange membranes.

[0010] In conjunction with the first aspect, in an optional embodiment of this application, R1 is a group containing at least one phenyl group; or, R1 is a group containing at least two phenyl groups.

[0011] The above technical solutions are beneficial for further improving the ionic conductivity of anion exchange membranes and reducing their swelling rate, thereby further broadening the application range of anion exchange membranes.

[0012] In conjunction with the first aspect, in an optional embodiment of this application, R1 is selected from substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, or substituted or unsubstituted polycyclic aromatic hydrocarbon groups.

[0013] In the above technical solution, R1 is selected from the above-mentioned groups, which is beneficial to further improve the ionic conductivity of the anion exchange membrane and reduce the swelling rate of the anion exchange membrane, thus further broadening the application range of the anion exchange membrane.

[0014] Optionally, R1 is selected from the following groups:

[0015]

[0016]

[0017] In conjunction with the first aspect, in an optional embodiment of this application, R2 + X is a positively charged cyclic amine group; or / and X is selected from at least one of hydroxyl, chlorine, bromine, iodine, p-toluenesulfonyloxy, trifluoromethanesulfonic acid, and methanesulfonyloxy; or / and the number average molecular weight of the ion-conducting polymer is 10,000-200,000 Da.

[0018] The above technical solutions are beneficial for further improving the ionic conductivity of anion exchange membranes and reducing their swelling rate, thereby further broadening the application range of anion exchange membranes.

[0019] Optionally, R2 + It is selected from at least one of imidazolium, pyridinium, pyrazolium, pyrrolidineonium, pyrroloinium, pyrimidineonium, piperidinium, indoleonium, and triazineonium.

[0020] Optionally, R2 + It is selected from at least one of imidazolium and piperidinium.

[0021] Optionally, R2 + It is selected from at least one of tetramethylimidazolium and N-methylpiperidinium.

[0022] Optionally, X is selected from at least one of chlorine, bromine, and iodine atoms.

[0023] In conjunction with the first aspect, in an optional embodiment of this application, the ion-conducting polymer has the following structural formula: Where n≥2; or, the structural formula of the ion-conducting polymer is as follows:

[0024] Where n≥2; or, the structural formula of the ion-conducting polymer is as follows:

[0025] Where n1≥2, n2≥2.

[0026] In the above technical solution, the ion-conducting polymer is the polymer provided above. Through the interaction between the main chain backbone and the phenyl, methylene and N-methylpiperidinium in the side chain, the anion exchange membrane prepared by cross-linking the ion-conducting polymer can have a low swelling ratio (≤12.4% at 25℃) and a high ionic conductivity (≥54mS / cm at 25℃). The anion exchange membrane has good electrochemical performance and a long service life, which greatly broadens the application range of anion exchange membranes.

[0027] Optionally, the ratio of n1 to n2 is 1:(0.5-1.5).

[0028] In a second aspect, this application provides a method for preparing an ion-conducting crosslinked polymer, the method comprising: subjecting the ion-conducting polymer provided in any of the first aspects above to a crosslinking reaction in the presence of a crosslinking agent.

[0029] The ion-conducting crosslinking compound provided in this application is obtained by crosslinking the ion-conducting polymer provided in the first aspect above. This allows the anion exchange membrane prepared using the ion-conducting crosslinking compound to have both high ion conductivity and low swelling ratio. This results in the anion exchange membrane having both good electrochemical performance and a long service life, which greatly expands the application range of anion exchange membranes.

[0030] In conjunction with the second aspect, in an optional embodiment of this application, the crosslinking agent has the following structural formula: Where A1 is a substituted or unsubstituted aryl group, and y1 and y2 are each independent natural numbers from 0 to 5. Alternatively, the crosslinking agent has the following structural formula: R3-(A2). y3 -R4; wherein A2 is selected from alkyl, aryl, alkenyl or alkynyl, y3 is 0 or 1, and R3 and R4 are each independently cyclic amino groups.

[0031] In the above technical solution, the crosslinking agent is selected from the compounds provided above, which enables the ion-conducting polymer provided in the first aspect to be effectively crosslinked.

[0032] Thirdly, this application provides an anion exchange membrane, the material of which includes an ion-conducting crosslinker prepared by the preparation method of the ion-conducting crosslinker provided in any of the second aspects above.

[0033] The anion exchange membrane provided in this application has both high ionic conductivity and low swelling ratio, meaning that the anion exchange membrane has both good electrochemical performance and long service life, which is beneficial to greatly expanding the application range of anion exchange membranes.

[0034] Optionally, the anion exchange membrane includes a porous support layer and a filler material filling the pores of the porous support layer, wherein the filler material includes inorganic hydrophilic particles and ion-conducting crosslinkers; or, the anion exchange membrane includes a porous support layer and a filler material filling the pores of the porous support layer, wherein the filler material includes ion-conducting crosslinkers; or, the anion exchange membrane includes inorganic hydrophilic particles and ion-conducting crosslinkers.

[0035] Fourthly, this application provides an application of the anion exchange membrane as described in the third aspect above in the preparation of water electrolysis devices, electrodialysis devices, fuel cells, or electrochemical energy storage devices; the electrochemical energy storage devices include flow batteries. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is the mass spectrum of the product obtained in step (1) of Example 1 of this application.

[0038] Figure 2 This is the mass spectrum of the product obtained in step (1) of Example 2 of this application.

[0039] Figure 3 The image shows the 1H NMR spectrum of the crosslinking agent obtained in step (3) of Example 3 of this application.

[0040] Figure 4 This is the mass spectrum of the product obtained in step (1) of Comparative Example 1 of this application. Detailed Implementation

[0041] This application provides an ion-conducting polymer, the structural formula of which is as follows:

[0042] Where m≥0, n≥2, z is 0 or 1, and m and z are not both 0; R1 is a group containing a phenyl group; R2 is a quaternary ammonium group; X - It is an anion.

[0043] This application modifies the groups in the side chains connected to the main chain backbone of an ion-conducting polymer, and uses this ion-conducting polymer for crosslinking to prepare anion exchange membranes. This not only improves the ionic conductivity of the anion exchange membrane, giving it better electrochemical properties, but also reduces its swelling ratio and improves its alkali stability, resulting in a longer service life. Therefore, the ion-conducting polymer provided in this application greatly expands the application range of anion exchange membranes.

[0044] The inventors speculate that the reason why the ion-conducting polymer provided in this application can enable the anion exchange membrane to have a high ion conductivity may be that: in the ion-conducting polymer provided in this application, the side chains connected to the main chain backbone have phenyl groups and / or at least two methylene groups. The π effect provided by the phenyl groups can promote the self-aggregation of the molecular structure and realize the construction of the hydrophobic region, while the flexible segments of the at least two methylene groups also contribute to the construction of the hydrophobic region; the side chains connected to the main chain backbone have quaternary ammonium groups. With the help of the above-mentioned construction of the hydrophobic region, the quaternary ammonium groups can be effectively adjacent to each other to realize the construction of the hydrophilic region, and thus the hydrophilic microcrystalline region can be effectively constructed to achieve a uniform distribution of the phase-separated microcrystalline region, thereby achieving efficient ion conduction.

[0045] In some optional embodiments of this application, 10 ≥ m ≥ 0; this is beneficial for further improving the ionic conductivity of the anion exchange membrane and reducing the swelling rate of the anion exchange membrane, thereby further broadening the application range of the anion exchange membrane.

[0046] As an example, the value of m can be any point value among 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, or a range of values ​​between any two.

[0047] In some optional embodiments of this application, z = 1; the above configuration allows the side chains connected to the main chain backbone to have phenyl groups. The Π effect provided by the phenyl groups can promote the self-aggregation of the molecular structure, which helps to further promote the construction of microcrystalline regions, thereby further achieving a uniform distribution of phase-separated microcrystalline regions. This is beneficial to further improve the ionic conductivity of the anion exchange membrane and reduce the swelling rate of the anion exchange membrane, thus further broadening the application range of the anion exchange membrane.

[0048] Furthermore, in some optional embodiments of this application, 10 ≥ m ≥ 0 and z = 1; the above configuration allows the side chains connected to the main chain backbone to simultaneously contain phenyl groups and at least one methylene group, which helps to further promote the construction of microcrystalline regions, thereby further achieving a uniform distribution of phase-separated microcrystalline regions, which is beneficial to further improve the ionic conductivity of the anion exchange membrane and reduce the swelling rate of the anion exchange membrane, and further broadens the application range of the anion exchange membrane.

[0049] In some optional embodiments of this application, R1 is a group containing at least one phenyl group. R1 is selected from groups containing at least one phenyl group, which can enhance the Π effect, thereby helping to promote the self-aggregation of molecular structures, helping to promote the construction of microcrystalline regions, and thus achieving a uniform distribution of phase-separated microcrystalline regions. This is beneficial to improving the ionic conductivity of the anion exchange membrane and reducing the swelling rate of the anion exchange membrane, further broadening the application range of the anion exchange membrane.

[0050] Furthermore, in some optional embodiments of this application, R1 is a group containing at least two phenyl groups; the presence of at least two phenyl groups in R1 can enhance the Π effect, thereby further promoting the self-aggregation of the molecular structure, further promoting the construction of the microcrystalline region, and further achieving a uniform distribution of the phase-separated microcrystalline region. This is beneficial for further improving the ionic conductivity of the anion exchange membrane and reducing the swelling rate of the anion exchange membrane, thus further broadening the application range of the anion exchange membrane.

[0051] In some optional embodiments of this application, R1 is selected from substituted or unsubstituted phenyl groups, substituted or unsubstituted biphenyl groups, and substituted or unsubstituted polycyclic aromatic hydrocarbon groups. Selecting R1 from the above groups is beneficial for further improving the ionic conductivity of the anion exchange membrane and reducing its swelling rate, thereby further broadening the application range of the anion exchange membrane.

[0052] In this application, biphenyl refers to a group having two or more benzene rings connected by carbon-carbon single bonds, such as biphenyl, biphenyl or biphenyl, etc.; polycyclic aromatic hydrocarbon group refers to a compound having two or more benzene rings connected in a fused ring form, such as tetraphenyl, pentaphenyl, naphthalene, anthracene, phenanthrene, pyrene, indene, acenaphthene, fluorene or azulene, etc.

[0053] As an example, when R1 is selected from a substituted biphenyl group, the substituent on the biphenyl group can be an alkyl, aryl, alkenyl, or halogen atom, etc.; when R1 is selected from a substituted polycyclic aromatic hydrocarbon group, the substituent on the polycyclic aromatic hydrocarbon group can be an alkyl, aryl, alkenyl, or halogen atom, etc.

[0054] In some optional embodiments of this application, R1 is selected from the following groups:

[0055] R1 is selected from the above-mentioned groups, which is beneficial to further improve the ionic conductivity of the anion exchange membrane and reduce the swelling rate of the anion exchange membrane, thus further broadening the application range of the anion exchange membrane.

[0056] Furthermore, in some optional embodiments of this application, R1 is selected from the following groups:

[0057] R1 is selected from the above-mentioned groups, which is beneficial to further improve the ionic conductivity of the anion exchange membrane and reduce the swelling rate of the anion exchange membrane, thus further broadening the application range of the anion exchange membrane.

[0058] In some optional embodiments of this application, R2 + It is a positively charged cyclic amine group; this is beneficial for further improving the ionic conductivity and alkaline stability of anion exchange membranes, and further broadens the application range of anion exchange membranes.

[0059] In some optional embodiments of this application, R2 + Selected from at least one of imidazolium, pyridinium, pyrazolium, pyrrolidineonium, pyrrolomium, pyrimidineonium, piperidinium, indoleonium, and triazineonium; R2 + The selection of the above-mentioned groups is beneficial to further improve the ionic conductivity and alkaline stability of anion exchange membranes, and further broadens the application range of anion exchange membranes.

[0060] In some optional embodiments of this application, R2 + Selected from at least one of imidazolium and piperidinium; R2 + The selection of the above-mentioned groups is beneficial to further improve the ionic conductivity and alkaline stability of anion exchange membranes, and further broadens the application range of anion exchange membranes.

[0061] In some optional embodiments of this application, R2 + R2 is selected from at least one of tetramethylimidazolium and N-methylpiperidinium; + The selection of the above-mentioned groups is beneficial to further improve the ionic conductivity and alkaline stability of anion exchange membranes, and further broadens the application range of anion exchange membranes.

[0062] It should be noted that in some optional embodiments of this application, R2 + It can also be selected from other positively charged cyclic amino groups.

[0063] In some optional embodiments of this application, X is selected from at least one of hydroxyl, chlorine atom, bromine atom, iodine atom, p-toluenesulfonyloxy (OTs), trifluoromethanesulfonic acid (OTf), and methanesulfonyloxy (OMs); when X is selected from the above groups, it is beneficial to further improve the ionic conductivity of the anion exchange membrane and further broaden the application range of the anion exchange membrane.

[0064] In some optional embodiments of this application, X is selected from at least one of chlorine atom, bromine atom, and iodine atom; when X is selected from the above-mentioned groups, it is beneficial to further improve the ionic conductivity of the anion exchange membrane and further broaden the application range of the anion exchange membrane.

[0065] In some optional embodiments of this application, X is selected from chlorine atoms, which can reduce the cost of ion-conducting polymers and is beneficial for industrial production.

[0066] It should be noted that in other feasible embodiments of this application, X - It can also be selected from other anions.

[0067] In some optional embodiments of this application, the number average molecular weight of the ion-conducting polymer is 10,000-200,000 Da. If the number average molecular weight of the ion-conducting polymer is large, it is not conducive to further improving the mechanical strength of the anion exchange membrane. If the number average molecular weight of the ion-conducting polymer is small, the viscosity of the ion-conducting polymer will be large, which is not conducive to improving the film-forming effect of the anion exchange membrane.

[0068] As an example, the number average molecular weight of the ion-conducting polymer can be any one of 10,000 Da, 20,000 Da, 50,000 Da, 75,000 Da, 100,000 Da, 120,000 Da, 150,000 Da, 175,000 Da, and 200,000 Da, or a range between any two.

[0069] In some optional embodiments of this application, the structural formula of the ion-conducting polymer is shown in Formula I, which is as follows:

[0070] Where n≥2.

[0071] The structural formula of the ion-conducting polymer is shown in Formula II, which is as follows:

[0072] Where n≥2;

[0073] The structural formula of the ion-conducting polymer is shown in Formula III, which is as follows:

[0074] Where n1≥2, n2≥2; further, the ratio of n1 to n2 can be 1:(0.5-1.5).

[0075] The ion-conducting polymer is the polymer provided by Formula I, Formula II or Formula III above. Through the interaction between the main chain backbone and the phenyl, methylene and N-methylpiperidinium in the side chain, the anion exchange membrane prepared by crosslinking the ion-conducting polymer can have a low swelling ratio (≤12.4% at 25℃) and a high ionic conductivity (≥54mS / cm at 25℃). The anion exchange membrane has good electrochemical performance and a long service life, which greatly broadens the application range of anion exchange membranes.

[0076] Furthermore, compared to the polymers shown in Formula I or Formula II, the polymer shown in Formula III allows the anion exchange membrane prepared by crosslinking the ion-conducting polymer to have a lower swelling ratio (approximately 9.6% at 25°C) and a higher ionic conductivity (approximately 64.9 mS / cm at 25°C).

[0077] This application also provides a method for preparing the above-mentioned ion-conducting polymer, the method comprising: subjecting a mixture containing a free radical initiator, a monomer, and an organic solvent to a self-polymerization reaction; wherein the monomer has the following structural formula:

[0078] For information on m, z, R1, R2, and X, please refer to the relevant content on ion-conducting polymers mentioned above; they will not be repeated here.

[0079] In some optional embodiments of this application, the free radical initiator is selected from free radical initiators or redox initiators, including peroxide initiators and azo initiators. For example, the free radical initiator is azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide, tert-butyl peroxide, or methyl ethyl ketone peroxide, etc.

[0080] Furthermore, in some optional embodiments of this application, the free initiator is azobisisobutyronitrile (AIBN). AIBN has a suitable reaction temperature and a controllable reaction rate.

[0081] In some optional embodiments of this application, the temperature of the self-polymerization reaction is 60-100°C, and the reaction time is 1-26 hours. Under these conditions, the self-polymerization reaction can proceed more effectively, which is beneficial to improving the controllability of the self-polymerization reaction.

[0082] Furthermore, in some optional embodiments of this application, the temperature of the self-polymerization reaction is 70-90°C, and the time of the self-polymerization reaction is 1-24 hours.

[0083] In some optional embodiments of this application, the molar amount of the free radical initiator is 0.1-5.0% of the molar amount of the monomer. In this case, the self-polymerization reaction can proceed better, which is beneficial to improving the controllability of the self-polymerization reaction. Further, the molar amount of the free radical initiator is 0.5-3.0% of the molar amount of the monomer.

[0084] In some optional embodiments of this application, during the self-polymerization reaction, the organic solvent is selected from at least one of N-methylpyrrolidone, N,N-dimethylformamide, dimethylacetamide, methanol, ethanol, isopropanol, acetonitrile, and dioxane. Selecting the organic solvent from the above substances is beneficial for improving the solubility of the monomer in the organic solvent, allowing the self-polymerization reaction to proceed better, and enhancing the controllability of the self-polymerization reaction.

[0085] Furthermore, in some optional embodiments of this application, the monomer accounts for 5-50% of the volume fraction of the organic solvent.

[0086] This application also provides a method for preparing an ion-conducting crosslinked polymer, the method comprising: subjecting the ion-conducting polymer provided in any of the first aspects above to a crosslinking reaction in the presence of a crosslinking agent.

[0087] The ion-conducting crosslinking compound provided in this application is obtained by crosslinking the aforementioned ion-conducting polymer. This allows the anion exchange membrane prepared using the ion-conducting crosslinking compound to have both high ion conductivity and low swelling ratio. Consequently, the anion exchange membrane can have both good electrochemical performance and a long service life, which greatly expands the application range of anion exchange membranes.

[0088] It should be noted that, in some optional embodiments of this application, after the ion-conducting polymer is prepared by the above-described method, no purification step is required, and a crosslinking agent can be directly added to carry out the crosslinking reaction.

[0089] In some optional embodiments of this application, the crosslinking agent has the structural formula shown in Formula III, which is as follows: Wherein, A1 is a substituted or unsubstituted aryl group, and y1 and y2 are each independent natural numbers from 0 to 5. The crosslinking agent selected from the compounds provided above enables the ion-conducting polymers provided above to be effectively crosslinked.

[0090] In some optional embodiments of this application, A1 is phenyl, and y1 and y2 are both 0.

[0091] Furthermore, divinylbenzene (DVB) is selected as the crosslinking agent because it is low in cost, has good crosslinking effect, and does not introduce other functional groups.

[0092] In some optional embodiments of this application, the crosslinking agent has the structural formula shown in Formula IV, which is as follows: R3-(A2) y3 -R4; where A2 is selected from alkyl, aryl, alkenyl, or alkynyl groups, y3 is 0 or 1, and R3 and R4 are each independently a cyclic amino group. Using the compounds provided above as crosslinking agents enables the ion-conducting polymers provided above to be effectively crosslinked. Furthermore, compared to the crosslinking agent shown in Formula III, the crosslinking agent shown in Formula IV not only improves the ionic conductivity of the anion exchange membrane, resulting in better electrochemical performance and a longer service life, but also greatly expands the application range of the anion exchange membrane.

[0093] Furthermore, A2 is aryl.

[0094] As an example, A2 can be a substituted aryl or an unsubstituted aryl. The aryl can be phenyl, naphthyl, fluorenyl, or a fused-ring aromatic compound, etc. The substituted aryl can be an alkyl-substituted aryl, an aryl-substituted aryl, an alkenyl-substituted aryl, or a halogen-substituted aryl, etc. For example, A2 can be phenyl, biphenyl, triphenyl, naphthyl, or fluorenyl, etc.

[0095] In some optional embodiments of this application, R3 and R4 are each independently selected from at least one of imidazolium, pyridinium, pyrazolium, pyrrolidineium, pyrroloinium, pyrimidineium, piperidinium, indoleium, and triazineium. The independent selection of R3 and R4 from the aforementioned groups is beneficial for further improving the ionic conductivity and alkalinity stability of the anion exchange membrane, thereby further extending its service life.

[0096] Furthermore, R3 and R4 are each independently selected from at least one of imidazolium and piperidinium, which allows the anion exchange membrane to have both high ionic conductivity and basic stability.

[0097] Furthermore, R3 and R4 are each independently selected from at least one of tetramethylimidazolium and N-methylpiperidinium. This is beneficial for further improving the ionic conductivity of the anion exchange membrane; at the same time, it is also beneficial for further reducing the swelling ratio of the anion exchange membrane and further improving the alkaline stability of the anion exchange membrane.

[0098] It should be noted that in other feasible embodiments of this application, R3 and R4 may also be independently selected from other cyclic amino groups.

[0099] It should be noted that in other feasible implementations, the crosslinking agent can also be a molecular structure containing two olefin units, such as 1,5-hexadiene.

[0100] In some optional embodiments of this application, the crosslinking reaction temperature is 40-150°C, and the crosslinking reaction time is 1-36 hours. Performing the crosslinking reaction under these conditions allows for better crosslinking and improves the controllability of the crosslinking reaction.

[0101] Furthermore, in some optional embodiments of this application, the crosslinking reaction temperature is 50-120°C, and the crosslinking reaction time is 1-36 hours.

[0102] This application provides an anion exchange membrane, the material of which includes an ion-conducting crosslinker prepared by the preparation method of the ion-conducting crosslinker as described above.

[0103] The anion exchange membrane provided in this application has both high ionic conductivity and low swelling ratio, meaning that the anion exchange membrane has both good electrochemical performance and long service life, which is beneficial to greatly expanding the application range of anion exchange membranes.

[0104] In some optional embodiments of this application, the anion exchange membrane includes the following three types:

[0105] Method 1: The anion exchange membrane includes a membrane substrate, the material of which is the anion-conducting crosslinking agent provided above.

[0106] As an example, the preparation method of the anion exchange membrane in Method 1 includes: casting an ion-conducting crosslinker onto a planar substrate and drying it to obtain a thin film on the planar substrate; immersing the dried thin film in a 1M KOH solution to obtain a hydroxide anion exchange membrane. The planar substrate can be polyethylene, polypropylene, polyethylene terephthalate, polytetrafluoroethylene, or glass, etc.; the drying temperature can be around 60°C, and the drying time can be 1-20 hours. Further, polyethylene terephthalate is selected as the planar substrate.

[0107] Method 2: The anion exchange membrane includes a porous support layer and a filler filling the pores of the porous support layer, wherein the filler is the ion-conducting crosslinker provided above.

[0108] As an example, the preparation method of the anion exchange membrane in Method 2 includes: casting an ion-conducting crosslinker into the pores of a porous support layer and then drying it; immersing the dried film-like material in a 1M KOH solution to obtain a hydroxide anion exchange membrane. The porous support layer is made of at least one of the following materials: polypropylene, polyethylene, polysulfone, polyphenylene sulfide, polyamide, polyethersulfone, polyphenylene sulfone, polyethylene terephthalate, polyetheretherketone, sulfonated polyetheretherketone, expanded polytetrafluoroethylene, trifluorochloroethylene, copolymers of ethylene and tetrafluoroethylene, copolymers of ethylene and trifluorochloroethylene, polyimide, polyetherimide, and meta-aromatic polyamide; the drying temperature can be around 60°C, and the drying time can be 1-20 hours; the porosity of the porous support layer is 40-90%; and the thickness of the porous support layer is 1-60 μm. Furthermore, the porous support layer is made of expanded polytetrafluoroethylene; the porosity of the porous support layer is 50-80%; and the thickness of the porous support layer is 2-40μm.

[0109] Method 3: The anion exchange membrane includes a porous support layer and a filler material filling the pores of the porous support layer. The filler material includes inorganic hydrophilic particles and ion-conducting crosslinkers as described above.

[0110] As an example, the preparation method of the anion exchange membrane in Method 3 includes: casting a liquid phase containing inorganic hydrophilic particles and ion-conducting crosslinkers into the pores of a porous support layer and then drying it; immersing the dried thin film material in a 1M KOH solution to obtain a hydroxide anion exchange membrane. The drying temperature can be around 60℃, and the drying time can be 1-20 hours. The inorganic hydrophilic particles include at least one of zirconium oxide, barium sulfate, hydrotalcite, titanium dioxide, zinc carbonate, magnesium hydroxide, nickel hydroxide, and hydrotalcite. The particle size of the inorganic hydrophilic particles is 1 nm-1 μm. The mass fraction of inorganic hydrophilic particles in the ion-conducting crosslinking material is ≤60%. The porous support layer is made of at least one of polypropylene, polyethylene, polysulfone, polyphenylene sulfide, polyamide, polyethersulfone, polyphenylene sulfone, polyethylene terephthalate, polyetheretherketone, sulfonated polyetheretherketone, expanded polytetrafluoroethylene, trifluorochloroethylene, copolymers of ethylene and tetrafluoroethylene, copolymers of ethylene and trifluorochloroethylene, polyimide, polyetherimide, and meta-aromatic polyamide. The porosity of the porous support layer is 40-90%. The thickness of the porous support layer is 1-60 μm. Furthermore, the inorganic hydrophilic particles are selected from zirconium oxide or barium sulfate, the particle size of the inorganic hydrophilic particles is 5nm-500nm, the mass fraction of the inorganic hydrophilic particles in the ion-conducting crosslinking material is 10-30%, the porous support layer is selected from expanded polytetrafluoroethylene, the porosity of the porous support layer is 50-80%, and the thickness of the porous support layer is 2-40μm.

[0111] Method 4: The anion exchange membrane includes a membrane substrate, the material of which includes the anion-conducting crosslinking material and inorganic hydrophilic particles provided above.

[0112] As an example, the preparation method of the anion exchange membrane in Method 4 includes: casting a liquid phase containing inorganic hydrophilic particles and ion-conducting crosslinkers onto a planar substrate, drying it to obtain a thin film on the planar substrate; immersing the dried thin film in a 1M KOH solution to obtain a hydroxide anion exchange membrane. The planar substrate can be polyethylene, polypropylene, polyethylene terephthalate, polytetrafluoroethylene, or glass, etc.; the inorganic hydrophilic particles include at least one of zirconium oxide, barium sulfate, hydrotalcite, titanium dioxide, zinc carbonate, magnesium hydroxide, nickel hydroxide, and hydrotalcite materials; the particle size of the inorganic hydrophilic particles is 1 nm-1 μm; the mass fraction of the inorganic hydrophilic particles in the ion-conducting crosslinkers is ≤60%; the drying temperature can be around 60°C, and the drying time can be 1-20 h. Furthermore, the planar substrate is selected from polyethylene terephthalate, and the inorganic hydrophilic particles are selected from zirconium oxide or barium sulfate. The particle size of the inorganic hydrophilic particles is 5nm-500nm, and the mass fraction of the inorganic hydrophilic particles in the ion-conducting crosslinking material is 10-30%.

[0113] This application provides an application of the anion exchange membrane as described in the third aspect above in the preparation of water electrolysis devices, electrodialysis devices, fuel cells or electrochemical energy storage devices; the electrochemical energy storage devices include flow batteries.

[0114] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0115] Example 1

[0116] This embodiment provides a method for preparing anion exchange membrane, including the following steps:

[0117] (1) Add 3.3 g of cyclopentadiene (CAS No.: 542-92-7) and 8.1 g of 5-chloro-1-pentene (CAS No.: 928-50-7) to a 100 mL sample bottle and react at 180 °C for 70 h; after the reaction is completed, distill off the unreacted raw materials at 120 °C with the bottle open to obtain the product; the structural formula of the product is as follows:

[0118]

[0119] The NMR signal of the product is: 1¹H NMR (400MHz, CDCl₃) 0.56–0.62 (m, 1H), 1.27–1.54 (m, 6H), 1.91 (m, 1H), 2.48–2.57 (m, 1H), 2.88 (m, 1H), 3.00 (m, 1H), 3.52 (m, 1H), 3.74 (m, 1H), 5.95 (m, 1H), 6.20 (m, 1H). The mass spectrum of the product is shown below. Figure 1 As shown, the molecular weight of the product is 170.08, which is consistent with the expected molecular weight of the structure.

[0120] (2) The product obtained in step (1) was reacted with N-methylpiperidine (CAS: 626-67-5) at a molar ratio of 1:1.1, using acetonitrile as solvent, and the reaction was stopped after 16 h at 80 °C. The solid was purified by centrifugation to obtain the monomer; the structural formula of the monomer is as follows:

[0121]

[0122] (3) Dissolve the monomer and AIBN obtained in step (2) in 800 μL of DMSO and react at 70 °C for 18 h; wherein the mass of the monomer is 400 mg and the molar amount of AIBN is 1% of the molar amount of the monomer.

[0123] Then, 8 mg of DVB (crosslinking agent) and 0.1% of AIBN (based on the molar amount of DVB) were added to the reaction system, and the reaction was carried out at 70 °C for 18 h to obtain the ion-conducting crosslinked product.

[0124] (4) The ion-conducting crosslinking material obtained in step (3) is cast onto a planar substrate of PET material and dried at 60°C for 3 hours to form a thin film. Then, the thin film is immersed in a 1M KOH solution for 12 hours to completely replace chloride ions with hydroxide ions. Then, the film is demolded to obtain an anion exchange membrane.

[0125] Example 2

[0126] This embodiment provides a method for preparing anion exchange membrane. The difference between this embodiment and Embodiment 1 is that steps (1) and (2) are different.

[0127] In this embodiment, step (1) is as follows: 2.2 g of cyclopentadiene (CAS No.: 542-92-7) and 7.6 g of 4-chloromethylstyrene (CAS No.: 1592-20-7) are added to a 100 mL sample bottle, and the mixture is reacted at 180 °C for 70 h; after the reaction is completed, the unreacted raw materials are distilled off at 120 °C with the bottle open to obtain the product; wherein, the structural formula of the product is as follows:

[0128]

[0129] The NMR signal of the product is: 1 ¹H NMR (400MHz, CDCl₃) 1.41–1.74 (m, 4H), 2.72 (m, 1H), 2.85–3.02 (m, 1H), 4.64 (s, 2H), 5.96 (m, 1H), 6.18 (m, 1H), 7.27–7.34 (m, 4H). The mass spectrum of the product is shown below. Figure 2 As shown, the molecular weight of the product is 218.08, which is consistent with the expected molecular weight of the structure.

[0130] In this embodiment, step (2) is as follows: The product obtained in step (1) is reacted with N-methylpiperidine (CAS: 626-67-5) at a molar ratio of 1:1.1, using acetonitrile as solvent, and the reaction is stopped after 16 h at 80 °C. The solid is purified by centrifugation to obtain the monomer; wherein, the structural formula of the monomer is as follows:

[0131]

[0132] Example 3

[0133] This embodiment provides a method for preparing anion exchange membrane. The difference between this embodiment and Embodiment 1 is that steps (3) and (4) are different.

[0134] In this embodiment, step (3) is as follows: the monomer and AIBN obtained in step (2) are dissolved in 800 μL of DMSO and reacted at 70 °C for 12 h; wherein, the mass of the monomer is 400 mg and the molar amount of AIBN is 1% of the molar amount of the monomer.

[0135] Then, 23.3 mg of crosslinking agent was added to the reaction system, and the reaction was carried out at 80 °C for 8 h to obtain the ion-conducting crosslinked product; the structural formula of the crosslinking agent is as follows:

[0136]

[0137] The preparation method of the above crosslinking agent includes: adding trimethylimidazole (CAS No.: 822-90-2, 30 mmol) to a dry 100 mL Shrek reaction flask containing 10 mL of anhydrous DMF, adding a clean stir bar and 20 mg of dehydrated molecular sieve, and adding 4,4'-dibromobiphenyl (CAS No.: 92-86-4, 10 mmol), cuprous thiophene-2-carboxylate (CAS No.: 68986-76-5, 4 mmol), 4,7-dimethoxy-1,10-phenanthroline (CAS No.: 92149-07-0, 4 mmol) and potassium tert-butoxide (60 mmol) in batches under stirring at room temperature. After the addition is complete, the mixture is subjected to three nitrogen purging treatments and placed in an oil bath, slowly heated to 160 °C, and reacted for 18 h. The crosslinking agent is then purified by column chromatography (eluent is methanol and dichloromethane in a volume ratio of 1:12) to obtain the crosslinking agent. The NMR spectrum of the crosslinking agent is as follows Figure 3 As shown, 1 ¹H NMR (400MHz, DMSO) δ 7.93 (d, J = 8.2Hz, 4H), 7.47 (d, J = 8.1Hz, 4H), 2.12 (s, 6H), 2.09 (s, 6H), 1.95 (s, 6H). The NMR results are consistent with the expected structure.

[0138] In this embodiment, step (4) is as follows: the ion-conducting crosslinker obtained in step (3) is cast onto a planar substrate of PET material, dried at 60°C for 3 hours to form a thin film, and then the thin film is immersed in a 1M KOH solution for 12 hours to completely replace chloride ions with hydroxide ions, and then demolded to obtain an anion exchange membrane.

[0139] Example 4

[0140] This embodiment provides a method for preparing anion exchange membrane. The difference between this embodiment and Embodiment 1 is that step (3) is different.

[0141] In this embodiment, step (3) is as follows: monomer a, monomer b, and AIBN are dissolved in 800 μL of DMSO and reacted at 70 °C for 18 h; wherein, the molar ratio of monomer a to b is 1:1, the total mass of monomer a and monomer b is 400 mg, and the molar amount of AIBN is 1% of the total molar amount of monomer a and monomer b. The structural formula of monomer a is as follows:

[0142]

[0143] The structural formula of monomer b is as follows:

[0144]

[0145] Then, 8 mg of DVB (crosslinking agent) and 0.1% AIBN (based on the molar amount of DVB) were added to the reaction system, and the reaction was carried out at 70 °C for 18 h to obtain the ion-conducting crosslinked product.

[0146] The ion-conducting crosslinker obtained in step (3) is cast onto a planar substrate of PET material and dried at 60°C for 3 hours to form a thin film. The thin film is then immersed in a 1M KOH solution for 12 hours to completely replace chloride ions with hydroxide ions. Finally, the film is demolded to obtain an anion exchange membrane.

[0147] Example 5

[0148] This embodiment provides a method for preparing anion exchange membrane. The difference between this embodiment and Embodiment 1 is that step (2) is different. In this embodiment, step (2) is as follows:

[0149] The product obtained in step (1) was reacted with tetramethylimidazole (CAS: 1739-83-9) at a molar ratio of 1:1.1 using acetonitrile as solvent. The reaction was stopped after 16 h at 80 °C. The solid was purified by centrifugation to obtain the monomer; the structural formula of the monomer is as follows:

[0150]

[0151] Example 6

[0152] This embodiment provides a method for preparing anion exchange membrane. The difference between this embodiment and Embodiment 1 is that step (4) is different. In this embodiment, step (4) is as follows:

[0153] Zirconia particles were added to the ion-conducting crosslinker obtained in step (3), and the mixture was stirred evenly and then the bubbles were removed under vacuum to obtain a mixed solution; wherein the mass fraction of zirconia particles in the mixed solution was 10%, and the average particle size of the zirconia particles was 20 nm.

[0154] A 5μm thick expanded polytetrafluoroethylene (ePTFE) membrane with a porosity of 60% was laid flat on a PET substrate. The mixture prepared above was then coated to fill the pores of the ePTFE membrane. The membrane was dried at 60°C for 3 hours to form a thin film containing filler in the pores of the ePTFE membrane. The dried film was then immersed in a 1M KOH solution for 12 hours to completely replace chloride ions with hydroxide ions. Finally, the membrane was demolded to obtain an anion exchange membrane.

[0155] Comparative Example 1

[0156] This embodiment provides a method for preparing anion exchange membrane, including the following steps:

[0157] (1) Add 3.3 g of cyclopentadiene (CAS No.: 542-92-7) and 8.1 g of 3-chloro-1-propene (CAS No.: 107-05-1) to a 100 mL sample bottle and react at 180 °C for 70 h; after the reaction is completed, distill off the unreacted raw materials at 120 °C with the bottle open to obtain the product; the structural formula of the product is as follows:

[0158]

[0159] The NMR signal of the product is: 1 ¹H NMR (400MHz, CDCl₃) 0.56–0.62 (m, 1H), 1.27–1.54 (m, 2H), 1.91 (m, 1H), 2.63 (m, 1H), 2.88 (m, 1H), 3.00 (m, 1H), 3.67 (m, 1H), 3.83 (m, 1H), 5.95 (m, 1H), 6.20 (m, 1H). The mass spectrum of the product is shown below. Figure 4 As shown, the molecular weight of the product is 156.07, which is consistent with the expected molecular weight of the structure.

[0160] (2) The product obtained in step (1) was reacted with N-methylpiperidine (CAS: 626-67-5) at a molar ratio of 1.1:1, using acetonitrile as solvent, and the reaction was stopped after 16 h at 80 °C. The solid was purified by centrifugation to obtain the monomer; the structural formula of the monomer is as follows:

[0161]

[0162] (3) Dissolve the monomer and AIBN obtained in step (2) in 800 μL of DMSO and react at 70 °C for 18 h; wherein the mass of the monomer is 400 mg and the molar amount of AIBN is 1% of the molar amount of the monomer.

[0163] Then, 8 mg of DVB (crosslinking agent) and 0.1% AIBN (based on the molar amount of DVB) were added to the reaction system, and the reaction was carried out at 70 °C for 18 h to obtain the ion-conducting crosslinked product.

[0164] (4) The ion-conducting crosslinking material obtained in step (3) is cast onto a planar substrate of PET material and dried at 60°C for 3 hours to form a thin film. Then, the thin film is immersed in a 1M KOH solution for 12 hours to completely replace chloride ions with hydroxide ions. Then, the film is demolded to obtain an anion exchange membrane.

[0165] Comparative Example 2

[0166] This comparative example provides a method for preparing anion exchange membrane. The difference between this comparative example and Example 1 lies in step (2). In this comparative example, step (2) is as follows:

[0167] (2) The product trimethylamine (CAS: 75-50-3) obtained in step (1) was reacted with acetonitrile at a molar ratio of 1:1.1, and the reaction was stopped after 16 h at 80 °C. The solid was purified by centrifugation and pulping to obtain the monomer; the structural formula of the monomer is as follows:

[0168]

[0169] Experimental Example 1

[0170] The swelling properties and ionic conductivity of the anion exchange membranes prepared in Examples 1-6 and Comparative Examples 1-2 were tested respectively, and the test results are shown in Table 1.

[0171] The swelling performance test method is as follows: The prepared anion exchange membrane is cut into square samples (3cm × 3cm), immersed in deionized water at 25℃ for 12 hours. After removing the membrane samples, the residual liquid on the surface of the membrane samples is quickly wiped off with filter paper, and the four side lengths of the membrane samples are measured. The average of the four side lengths is recorded as L1. Then, the membrane samples are dried at 60℃ for 0.5 hours, and the four side lengths of the membrane samples in the dry membrane state are measured. The average of the four side lengths is recorded as L2. The swelling rate of the anion exchange membrane is calculated as follows: Swelling rate = [(L2 - L1) / L1] × 100%.

[0172] The ionic conductivity was tested as follows: Hydroxide ionic conductivity was measured using a Metrohm Autolab PGSTAT128N electrochemical workstation. The prepared anion exchange membrane was soaked in 1M KOH aqueous solution for 12 hours, then repeatedly washed with deionized water until the KOH solution on the surface was completely removed. Hydroxide ionic conductivity was then measured using the four-probe method.

[0173] Table 1

[0174]

[0175] As can be seen from Table 1, the swelling ratio of the anion exchange membranes prepared in Examples 1-6 is lower than that of the anion exchange membranes prepared in Comparative Examples 1-2, and the ionic conductivity of the anion exchange membranes prepared in Examples 1-6 is higher than that of the anion exchange membranes prepared in Comparative Examples 1-2. This indicates that the anion exchange membranes prepared in Examples 1-7 have both good electrochemical properties and a long service life.

[0176] In summary, this application utilizes the crosslinking of the side chains connected to the main chain backbone of the ion-conducting polymer to prepare anion exchange membranes. This not only improves the ionic conductivity of the anion exchange membrane, resulting in better electrochemical properties, but also reduces its swelling rate and improves its alkali stability, leading to a longer service life and significantly expanding its application range.

[0177] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. An ion-conducting polymer, characterized in that, The structural formula of the ion-conducting polymer is as follows: Where m≥0, n≥2, z is 0 or 1, and m and z are not both 0; R1 is a group containing a phenyl group; R2 is a quaternary ammonium group; X - It is an anion.

2. The ion-conducting polymer according to claim 1, characterized in that, 10≥m≥0; or / and, z=1.

3. The ion-conducting polymer according to claim 2, characterized in that, R1 is a group containing at least one phenyl group; Alternatively, R1 is a group containing at least two phenyl groups.

4. The ion-conducting polymer according to claim 2, characterized in that, R1 is selected from substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, or substituted or unsubstituted polycyclic aromatic hydrocarbon group; Optionally, R1 is selected from the following groups:

5. The ion-conducting polymer according to any one of claims 1-4, characterized in that, R2 + It is a positively charged cyclic amino group; Or / and, X is selected from at least one of hydroxyl, chlorine atom, bromine atom, iodine atom, p-toluenesulfonyloxy, trifluoromethanesulfonic acid group and methanesulfonyloxy; Or / and, the number-average molecular weight of the ion-conducting polymer is 10,000-200,000 Da; Optionally, R2 + It is selected from at least one of imidazolium, pyridinium, pyrazolium, pyrrolidineonium, pyrroloinium, pyrimidineonium, piperidinium, indoleonium, and triazineonium; Optionally, R2 + Selected from at least one of imidazolium and piperidinium; Optionally, R2 + Selected from at least one of tetramethylimidazolium and N-methylpiperidinium; Optionally, X is selected from at least one of chlorine, bromine, and iodine atoms.

6. The ion-conducting polymer according to claim 1, characterized in that, The structural formula of the ion-conducting polymer is as follows: Where n≥2; Alternatively, the structural formula of the ion-conducting polymer is as follows: Where n≥2; Alternatively, the structural formula of the ion-conducting polymer is as follows: Where n1≥2, n2≥2; Optionally, the ratio of n1 to n2 is 1:(0.5-1.5).

7. A method for preparing an ion-conducting crosslinked compound, characterized in that, include: The ion-conducting polymer as described in any one of claims 1-6 is subjected to a crosslinking reaction in the presence of a crosslinking agent.

8. The method for preparing the ion-conducting crosslinked compound according to claim 7, characterized in that, The crosslinking agent has the following structural formula: Where A1 is a substituted aryl or an unsubstituted aryl, and y1 and y2 are each independent natural numbers from 0 to 5; Alternatively, the crosslinking agent may have the following structural formula: R3-(A2) y3 -R4; wherein A2 is selected from alkyl, aryl, alkenyl or alkynyl, y3 is 0 or 1, and R3 and R4 are each independently cyclic amino groups.

9. An anion exchange membrane, characterized in that, The material of the anion exchange membrane includes an ion-conducting crosslinker prepared by the method for preparing an ion-conducting crosslinker as described in claim 7 or 8; Optionally, the anion exchange membrane includes a porous support layer and a filler filling the pores of the porous support layer, wherein the filler includes inorganic hydrophilic particles and the ion-conducting crosslinker; or, the anion exchange membrane includes a porous support layer and a filler filling the pores of the porous support layer, wherein the filler includes the ion-conducting crosslinker; or, the anion exchange membrane includes inorganic hydrophilic particles and the ion-conducting crosslinker.

10. The application of the anion exchange membrane as described in claim 9 in the preparation of water electrolysis devices, electrodialysis devices, fuel cells or electrochemical energy storage devices; The electrochemical energy storage device includes a flow battery.

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