Polyacid covalent cross-linked aromatic proton exchange membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of design and synthesis of fuel cell proton exchange membranes, in particular to a polyacid covalent cross-linked aromatic proton exchange membrane and a preparation method and application thereof. The proton exchange material is obtained by grafting poly (1, 2-diphenylethane-isatin) with 3-bromopropane sodium sulfonate and 6-bromo-1-hexene, and then carrying out a thiol-ene click chemical reaction with Dawson type polyacid {P2W17-SH}, and the thiol-ene click chemical reaction is carried out on the grafted poly (1, 2-diphenylethane-isatin) and the Dawson type polyacid {P2W17-SH}. Wherein the grafting of the 3-bromopropane sodium sulfonate and the 6-bromine-1-hexene occurs in different repetitive units of the poly (1, 2-diphenylethane-isatin), and the Dawson type polyacid {P2W17-SH} and a vinyl side chain introduced by grafting the 6-bromine-1-hexene are subjected to a sulfydryl-ene click chemical reaction. The proton exchange membrane prepared by the invention effectively solves the problems of fuel cell fuel permeation, high cost, polyacid dissolution, dimensional stability, balance between conductivity and swelling and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell proton exchange membrane design and synthesis, and more specifically to a polyacid covalently cross-linked aromatic proton exchange membrane and a preparation method and application thereof. Background Art

[0002] Perfluorosulfonic acid membrane Its development is hampered by issues such as high fuel permeability, poor dimensional stability, and the high cost and environmental risks of perfluorinated production. Developed materials such as sulfonated polyaryletherketone (SPAEK), sulfonated polyethersulfone (SPES), and sulfonated polyimide (SPI) face dual challenges. First, under the action of catalysts, the large amounts of hydroxyl radicals (·OH) and hydroperoxyl radicals (·OOH) generated on the cathode side of the fuel cell are highly oxidizing. The ether bonds (COC) in the polymer backbone, due to their high electron cloud density, become the primary targets of free radical attack. Bond scission reactions are prone to occur during long-term operation, leading to depolymerization of the polymer backbone. This degradation process significantly shortens the service life of the membrane material. Second, the molecular design of the aromatic polymer, in which the sulfonic acid groups are directly bonded to the main chain benzene rings, makes it difficult for the acidic groups to achieve the unique dynamic aggregation characteristics of Nafion due to steric hindrance and the influence of the rigid backbone.

[0003] Therefore, one of the core issues is to ensure that the proton exchange membrane components in fuel cells can operate stably under harsh environments and have technical indicators such as high proton conductivity, high thermal stability, high chemical stability and low fuel permeability. Summary of the Invention

[0004] In order to address the deficiencies in the above-mentioned background technology, the present invention provides a polyacid covalently cross-linked aromatic proton exchange membrane and its preparation method and application. The present invention uses 1,2-diphenylethane and isatin as monomers, and synthesizes a poly (1,2-diphenylethane-isatin) (PIB) with a rigid benzene ring as the main chain skeleton through a one-step Friedel-Crafts reaction. PIB is grafted with sodium 3-bromopropane sulfonate. This branched comb-like structure gives the membrane sufficient microphase separation morphology and dense hydrophilic ion clusters, constructing long-range ordered proton transport channels; then, by grafting flexible side chains 6-bromo-1-hexene, and with an organic-inorganic crosslinker {P2W 17 -(SH)2} for thiol-ene click chemistry reaction; a series of covalently cross-linked composite membranes C-QSPIB were prepared.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] The first aspect of the present invention provides a polyacid covalently cross-linked aromatic proton exchange membrane, wherein poly 1,2-diphenylethane-isatin (PIB) is grafted with sodium 3-bromopropane sulfonate and 6-bromo-1-hexene, and then with a Dawson type polyacid {P2W 17 -(SH)2} is obtained after thiol-ene click chemistry reaction;

[0007] Among them, the grafting of sodium 3-bromopropane sulfonate and 6-bromo-1-hexene occurs on different repeating units of poly (1,2-diphenylethane)-isatin, Dawson type polyacid {P2W 17 -(SH)2} undergoes a thiol-ene click chemistry reaction with the vinyl side chain (i.e., a functional side chain with an unsaturated olefin structure) introduced when grafting 6-bromo-1-hexene.

[0008] The present invention is to graft the repeating unit structure PIB of the matrix polymer with sodium 3-bromopropane sulfonate and 6-bromo-1-hexene to generate a matrix containing an unsaturated olefin side chain structure, and to utilize the bifunctional thiol functionalized Dawson type polyacid {P2W 17 -(SH)2} undergoes thiol-ene click chemistry reaction with the functional side chain to obtain a cross-linked proton exchange membrane.

[0009] In a preferred embodiment, poly (1,2-diphenylethane)-isatin grafted sodium 3-bromopropane sulfonate and 6-bromo-1-hexene has the following structural units:

[0010]

[0011] Wherein, n represents the number of repeating units of 1,2-diphenylethane-isatin, m represents the number of repeating units containing sodium 3-bromopropanesulfonate side chain, and nm represents the number of repeating units containing vinyl side chain structure;

[0012] The microscopic structural units of the proton exchange membrane are as follows:

[0013]

[0014] Wherein, z represents the number of repeating units containing vinyl side chains in the polymer segment that participate in the thiol-ene click chemistry reaction; nmz represents the number of repeating units containing vinyl side chains in the polymer segment that do not participate in the thiol-ene click chemistry reaction.

[0015] The second aspect of the present invention provides a method for preparing a polyacid covalently cross-linked aromatic proton exchange membrane, comprising the following steps:

[0016] Synthesis of S1 and SPIB-M:

[0017] Poly (1,2-diphenylethane-isatin) (PIB) was dissolved in the first organic solvent, and then NaOH and sodium 3-bromopropane sulfonate were added under an inert gas atmosphere. The mixture was reacted for 24 hours to obtain sulfonated poly (1,2-diphenylethane-isatin) (SPIB-M). The reaction formula is as follows:

[0018]

[0019] Among them, the repeating unit with a degree of polymerization of m represents a polymer segment grafted with sodium 3-bromopropane sulfonate; the repeating unit with a degree of polymerization of (nm) represents a polymer segment containing a vinyl side chain structure; M represents the percentage between the repeating unit m of the polymer segment grafted with sodium 3-bromopropane sulfonate and the repeating unit n containing 1,2-diphenylethane-isatin, that is, the degree of sulfonation.

[0020] Synthesis of S2, QSPIB-M:

[0021] The SPIB-M obtained in step S1 is dissolved in a second organic solvent. After dissolution, NaOH is added, and 6-bromo-1-hexene is added at 80° C. and reacted for 48 hours to obtain QSPIB-M. The reaction formula is as follows:

[0022]

[0023] Wherein, the repeating unit with a degree of polymerization (nm) represents a polymer segment containing a vinyl side chain structure;

[0024] S3. Preparation of POM-N-QSPIB-M composite membrane:

[0025] The QSPIB-M obtained in step S2 is dissolved in a third organic solvent and dispersed by ultrasonication to obtain a QSPIB solution; the Dawson-type polyacid {P2W 17 -(SH)2} is dispersed in a third organic solvent and stirred magnetically to obtain {P2W 17 -(SH)2} dispersion; under vigorous stirring conditions, {P2W 17 -(SH)2} dispersion was added dropwise to the QSPIB solution to obtain a precursor solution; the precursor solution was spread on a substrate, and then irradiated with an ultraviolet light source. After maintaining a constant temperature of 80°C for 12 hours, the precursor solution was immersed in deionized water, and the substrate was peeled off in a water bath to obtain a proton exchange membrane POM-N-QSPIB-M; the wavelength of the ultraviolet light source was 365nm, and the power density was 10mW / cm 2 ;

[0026] Wherein, N represents the percentage of the number of repeating units containing vinyl side chains participating in the thiol-ene click chemistry reaction in the polymer segment, z, to the number of repeating units (nm) of the polymer segment (containing vinyl side chains), in %. The unit is %.

[0027] In a preferred embodiment, the preparation method of poly 1,2-diphenylethane-isatin comprises dissolving 1,2-diphenylethane and isatin in a mixed solution of CH2Cl2 and trifluoroacetic acid, and then adding trifluoromethanesulfonic acid dropwise to the dissolved solution in an ice bath at a uniform rate, and reacting at room temperature for 12 hours to obtain the obtained product. The reaction formula is as follows:

[0028]

[0029] In a preferred embodiment, the molar ratio of 1,2-diphenylethane, isatin, CH2Cl2, trifluoroacetic acid and trifluoromethanesulfonic anhydride is 1:1.02:11.4:12.7:14.6.

[0030] In a preferred embodiment, the first organic solvent, the second organic solvent, the third organic solvent and the fourth organic solvent are each independently selected from one of CH2Cl2, dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide.

[0031] In a preferred embodiment, in step S1, the molar ratio of poly (1,2-diphenylethane)-isatin, NaOH and sodium 3-bromopropane sulfonate is 1:2:0.8.

[0032] In a preferred embodiment, in step S2, the molar ratio of SPIB-M, 6-bromo-1-hexene and NaOH is 1:0.2:5.

[0033] In the preferred embodiment, in step S3, QSPIB-M, thiol-functionalized Dawson-type polyacid {P2W 17 The mass ratio of {P2W} is 1:0.6, the mass concentration of QSPIB-M solution is 10%, 17 The mass concentration of the dispersion is 10%.

[0034] The first aspect of the present invention provides an application of the proton exchange membrane provided in the first aspect of the present invention as a proton exchange membrane of a fuel cell.

[0035] The beneficial effects of the present invention are:

[0036] Perfluorosulfonic acid membrane The high fuel permeability, poor dimensional stability, high cost and environmental risks of perfluorinated production are problems that restrict its development. 17-(SH)2} as an organic-inorganic crosslinker, followed by a thiol-ene click chemistry covalent crosslinking reaction with a sulfonated ether-free aromatic polymer (QSPIB) with a high density of flexible olefin side chains. This POM and covalent crosslinking approach can address issues such as fuel permeation, high cost, polyacid dissolution, dimensional stability, and the trade-off between conductivity and swelling.

[0037] First, the present invention utilizes organic functionalized polyacids as inorganic dopants, covalently grafted onto polymer backbone structures to construct structurally stable composite proton exchange membranes. Organic modification is performed on the surface of Dawson-type polyacid materials to produce organic functionalized polyacid complexes with a bifunctional structure. Click chemistry is used to anchor the monofunctional organic functionalized polyacids to the side chains of the polymer to prevent their dissolution, thereby regulating the composite membrane's microphase separation structure, antioxidant decomposition capacity, and the polyacid's dissolution-preventing effect.

[0038] Secondly, the present invention uses a bifunctional organic functionalized polyacid as a cross-linking site to construct a covalent cross-linking structure between the polymer side chains. On the premise that the polyacid provides additional proton transfer sites, the mechanical strength, thermal / chemical stability and fuel penetration resistance of the composite membrane are improved, and the problem of excessive swelling of the membrane material in a high-temperature environment due to the introduction of a strongly hydrophilic polyacid is suppressed, thereby comprehensively solving the contradiction between the modified proton exchange membrane in increasing the proton conductivity and improving the structural stability of the membrane.

[0039] Third, the thiol-ene click chemistry cross-linking reaction of the present invention can form a three-dimensional network structure. This structure can effectively limit the slippage of the molecular chain, enhance the material's ability to resist deformation, and improve the swelling problem of the composite membrane caused by excessive water absorption, so that the mechanical properties of the polymer POM-10-QSPIB-80 reach 36.4MPa, which is about 3 times that of commercial Nafion. It also greatly optimizes the methanol permeability of the composite membrane, reducing the methanol permeability of POM-10-QSPIB-80 by about an order of magnitude compared to commercial Nafion. Thanks to the superiority of the organic-polyacid cross-linker, in terms of antioxidant properties, the mass loss rate in the Fenton reagent at 80°C for 1h is 5.8%; in terms of proton conduction, a P2W-containing cross-linked membrane is formed in the composite membrane. 17 The dense hydrogen bond network and multiple proton transport pathways formed by water, sulfonic acid groups and water, as well as a very small amount of free cross-linking agent and sulfonic acid groups, make the proton conductivity of POM-10-QSPIB-80 reach 0.28S·cm at 80℃ and 100%RH. -1 , and the swelling rate is only 19.9%, which is a performance that Nafion and polyarylether materials cannot achieve. DETAILED DESCRIPTION

[0040] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the examples described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0041] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. The experimental methods in the examples are conventional methods unless otherwise specified. Where specific conditions are not specified in the examples, the experiments were carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, for which the manufacturer is not specified, are all commercially available conventional products.

[0042] The preparation method of the proton exchange membrane provided by the present invention comprises the following steps: using 1,2-diphenylethane and isatin as monomers, synthesizing a poly (1,2-diphenylethane-isatin) (PIB) having a rigid benzene ring as a main chain skeleton through a one-step Friedel-Crafts reaction; using sodium 3-bromopropane sulfonate to graft-modify the PIB to generate a hydrophilic chain segment with a flexible comb-like structure, and combining the structure to give the membrane sufficient microphase separation morphology and dense hydrophilic ion clusters, thereby constructing a long-range ordered proton transport channel; then using 6-bromo-1-hexene to graft-modify the remaining PIB repeating units to introduce a functional side chain with an unsaturated olefin structure, and then by reacting with {P2W 17 A series of covalently cross-linked composite membranes, CN-QSPIB-M, were prepared by thiol-ene click chemistry using a thiol-(SH)2}-based catalyst. The proton exchange membranes prepared in this way effectively address fuel cell issues such as fuel permeation, high cost, polyacid dissolution, dimensional stability, and the trade-off between conductivity and swelling.

[0043] Example 1

[0044] 1. Synthesis of Poly (1,2-diphenylethane)-Isatin (PIB)

[0045] As shown in formula (1), 2 mol of 1,2-diphenylethane and 2.05 mol of isatin were dissolved in 2.8 L of CHCl and 1.54 L of trifluoroacetic acid (TFA). After the system was mixed evenly, the reaction apparatus was transferred to an ice bath. 1.54 L of trifluoromethanesulfonic acid (TFSA) was slowly added dropwise to the system via a constant pressure dropping funnel (the addition rate was controlled at 0.5 L / min), and the reaction was maintained at room temperature for 12 hours.

[0046]

[0047] 2. Synthesis of Sulfonated Poly (1,2-Diphenylethane)-Indigo Carmine (SPIB-M)

[0048] The synthesis of SPIB-M is shown in formula (2), where M represents the percentage between the repeating unit m of the polymer segment grafted with sodium 3-bromopropanesulfonate and the repeating unit n containing 1,2-diphenylethane-isatin, i.e., the degree of sulfonation, in %.

[0049] Taking SPIB-80 as an example, 4 mol of PIB was first dissolved in 6 L of dimethyl sulfoxide (DMSO). Under nitrogen, 6.4 mol of NaOH and 3.2 mol of sodium 3-bromopropane sulfonate were added sequentially to the reaction system. After the reactants were completely dissolved, the reaction system was heated to 80°C and stirred at 600 rpm for 24 hours to complete the sulfonation reaction. Similarly, the synthesis of SPIB-M (M = 0-100) samples was achieved by adjusting the amounts of catalyst (NaOH) and sulfonating agent (sodium 3-bromopropane sulfonate) in equimolar ratios, with a molar ratio of PIB to NaOH to sodium 3-bromopropane sulfonate of 100:2 (M:M).

[0050]

[0051] The best comprehensive performance is SPIB-80, with a conductivity of 0.183S·cm -1 (80℃ hydration condition), the mechanical strength is 40.75MPa. The electrical conductivity of SPIB-80 and SPIB-100 are 0.124S·cm -1 and 0.233S·cm -1 (80℃ hydration condition). The mechanical strengths are 45.13MPa and 33.84MPa respectively.

[0052] This invention uses 1,2-diphenylethane and isatin as monomers, synthesizing poly(1,2-diphenylethane-isatin) (PIB) with a rigid benzene ring backbone via a one-step Friedel-Crafts reaction. PIB is grafted onto sodium 3-bromopropane sulfonate. This flexible, comb-like structure imparts sufficient microphase separation and dense hydrophilic ion clusters to the membrane, establishing long-range, ordered proton transport channels. Comparison of the membrane's proton conductivity and mechanical properties demonstrates that SPIB-80 exhibits superior overall performance.

[0053] 3. Synthesis of SPIB-M grafted 6-bromo-1-hexene (QSPIB-M)

[0054] The synthesis process of QSPIB-M is shown in formula (3). Taking QSPIB-80 as an example, 4 mol of SPIB-80 was dissolved in 6 L of DMSO, followed by the addition of 1.6 mol of NaOH. After the reaction temperature was raised to 50°C, 0.8 mol of 6-bromo-1-hexene was added and the reaction was continued for 48 h. The final product was obtained.

[0055]

[0056] 4. Preparation of Composite Membrane (POM-N-QSPIB-M)

[0057] The preparation process of the composite membrane POM-N-QSPIB-M is as follows:

[0058] Taking POM-15-QSPIB-80 as an example, 100 mmol of QSPIB-80 polymer was first dissolved in 0.8 LDMSO and ultrasonicated for 0.5 h to form a homogeneous solution. Then 3 mmol of thiol-functionalized polyoxometalate K5H[α2-P2W 17 O 61 -{O[Si(CH2)3SH]2}]·6H2O(P2W 17 -(SH)2) was prepared in DMSO by magnetic stirring for 24 h at a speed of 1000 rpm to prepare a uniform dispersion system. 17 The dispersion of -(SH)2} was added dropwise to the QSPIB-80 solution to form a composite precursor solution. The membrane solution was then evenly spread on a clean glass plate for UV crosslinking treatment: a UV light source with a wavelength of 330 nm (power density 10 mW / cm 2 ) for 10 minutes, then the irradiation was turned off and the film was placed in a programmable temperature-controlled oven at 80°C for 12 hours. Finally, the cured film material was immersed in deionized water to complete the substrate peeling, and the resulting composite film was stored in deionized water for later use.

[0059] A series of hybrid membranes, designated POM-N-QSPIB-M, were prepared according to the above synthesis scheme. Similar POM-N-QSPIB-M samples were synthesized by adjusting the molar ratio of QSPIB-M to the thiol-functionalized polyoxometalate to 1000:2N. M represents the ratio of the repeating units m of the polymer segment grafted with sodium 3-bromopropanesulfonate to the repeating units n containing 1,2-diphenylethane-isatin, i.e., the degree of sulfonation (%). N represents the percentage of repeating units z containing vinyl side chains in the polymer segment that participate in the thiol-ene click chemistry reaction, relative to the total number of repeating units in the polymer segment (containing vinyl side chains) (nm). The resulting membranes all had thicknesses ranging from 40 to 100 μm.

[0060] In order to further optimize the proton conductivity, methanol permeation and oxidative stability of SPIB-80, we grafted a flexible side chain 6-bromo-1-hexene and combined it with an organic-inorganic crosslinker {P2W 17-(SH)2} through thiol-ene click chemistry reactions to prepare a series of covalently cross-linked composite membranes, POM-N-QSPIB-M. Studies have shown that thiol-ene click chemistry can form a three-dimensional network structure, which effectively limits molecular chain slippage, enhances the material's resistance to deformation, and alleviates the swelling problem of the composite membranes caused by excessive water absorption.

[0061] Among the series of polyacid covalently cross-linked aromatic proton exchange membranes POM-N-QSPIB-M prepared by the present invention, the mechanical properties of the polymer POM-10-QSPIB-80 reached 36.4MPa, which is about 3 times that of commercial Nafion. It also greatly optimized the methanol permeability of the composite membrane. The methanol permeability of POM-10-QSPIB-80 was reduced by about an order of magnitude compared with commercial Nafion. Thanks to the superiority of the organic-polyacid cross-linker, in terms of antioxidant properties, the mass loss rate in the Fenton reagent at 80°C for 1h was 5.8%; in terms of proton conduction, a P2W-containing cross-linked membrane was formed in the composite membrane. 17 The dense hydrogen bond network and multiple proton transport pathways formed by water, sulfonic acid groups and water, as well as a small amount of free cross-linking agent and sulfonic acid groups, make the proton conductivity of POM-10-QSPIB-80 reach 0.28S·cm at 80℃. -1 The results show that the swelling rate is only 19.9%, which is a performance that Nafion and polyarylether materials cannot achieve. This provides a reference for the future synthesis method and structural design of proton exchange membranes.

[0062] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A polyacid covalently cross-linked aromatic proton exchange membrane, characterized in that: Poly(1,2-diphenylethane)-isatin (PIB) was grafted with sodium 3-bromopropanesulfonate and 6-bromo-1-hexene, and then with Dawson-type polyacid {P2W 17 -(SH)2} is obtained after thiol-ene click chemistry reaction; Among them, the grafting of sodium 3-bromopropane sulfonate and 6-bromo-1-hexene occurs on different repeating units of poly (1,2-diphenylethane)-isatin, Dawson type polyacid {P2W 17 -(SH)2} undergoes a thiol-ene click chemistry reaction with the vinyl side chain introduced during the grafting of 6-bromo-1-hexene.

2. The polyacid covalently cross-linked aromatic proton exchange membrane according to claim 1, characterized in that: Poly (1,2-diphenylethane)-isotin grafted sodium 3-bromopropane sulfonate and 6-bromo-1-hexene has the following structural units: Wherein, n represents the number of repeating units of 1,2-diphenylethane-isatin, m represents the number of repeating units containing sodium 3-bromopropanesulfonate side chain, and nm represents the number of repeating units containing vinyl side chain structure; The microscopic structural units of the proton exchange membrane are as follows: Wherein, z represents the weight of the vinyl side chain in the polymer segment that participates in the thiol-ene click chemistry reaction. nmz represents the number of repeating units containing vinyl side chains in the polymer segment that do not participate in the thiol-ene click chemistry reaction.

3. A method for preparing a polyacid covalently cross-linked aromatic proton exchange membrane, characterized in that: The steps include: Synthesis of S1 and SPIB-M: Poly (1,2-diphenylethane-isatin) (PIB) was dissolved in a first organic solvent, and then NaOH and sodium 3-bromopropane sulfonate were added under an inert gas atmosphere and reacted for 24 hours to obtain sulfonated poly (1,2-diphenylethane-isatin) (SPIB-M). Synthesis of S2, QSPIB-M: The SPIB-M obtained in step S1 is dissolved in a second organic solvent, and after dissolution, NaOH is added, and 6-bromo-1-hexene is added at 80° C. and reacted for 48 hours to obtain QSPIB-M; S3. Preparation of POM-N-QSPIB-M composite membrane: The QSPIB-M obtained in step S2 is dissolved in a third organic solvent and dispersed by ultrasonication to obtain a QSPIB solution; the Dawson type polyacid {P2W 17 -(SH)2} is dispersed in a third organic solvent and stirred magnetically to obtain {P2W 17 -(SH)2} dispersion; under vigorous stirring conditions, {P2W 17 -(SH)2} dispersion was added dropwise to the QSPIB solution to obtain a precursor solution; The precursor solution was spread on a substrate and then irradiated with an ultraviolet light source. After being kept at a constant temperature of 80°C for 12 hours, the precursor solution was immersed in deionized water and the substrate was peeled off in a water bath to obtain a proton exchange membrane POM-N-QSPIB-M. The wavelength of the ultraviolet light source was 365 nm and the power density was 10 mW / cm 2 .

4. The method for preparing a polyacid covalently cross-linked aromatic proton exchange membrane according to claim 3, characterized in that: The preparation method of poly 1,2-diphenylethane-isatin comprises dissolving 1,2-diphenylethane and isatin in a mixed solution of CH2Cl2 and trifluoroacetic acid, and then uniformly adding trifluoromethanesulfonic acid dropwise to the dissolved solution in an ice bath, and reacting at room temperature for 12 hours to obtain the product.

5. The method for preparing a polyacid covalently cross-linked aromatic proton exchange membrane according to claim 4, characterized in that: The molar ratio of 1,2-diphenylethane, isatin, CH2Cl2, trifluoroacetic acid and trifluoromethanesulfonic anhydride is 1:1.02:11.4:12.7:14.

6.

6. The method for preparing a polyacid covalently cross-linked aromatic proton exchange membrane according to claim 3, characterized in that: The first organic solvent, the second organic solvent, the third organic solvent and the fourth organic solvent are each independently selected from one or more of CH2Cl2, dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide.

7. The method for preparing a polyacid covalently cross-linked aromatic proton exchange membrane according to claim 3, characterized in that: In step S1, the molar ratio of poly (1,2-diphenylethane)-isatin, NaOH and sodium 3-bromopropane sulfonate is 1:2:0.

8.

8. The method for preparing a polyacid covalently cross-linked aromatic proton exchange membrane according to claim 3, characterized in that: In step S2, the molar ratio of SPIB-M, 6-bromo-1-hexene and NaOH is 1:0.2:

5.

9. The method for preparing a polyacid covalently cross-linked aromatic proton exchange membrane according to claim 3, characterized in that: In step S3, QSPIB-M, Dawson type polyacid {P2W 17 The mass ratio of {P2W} is 1:0.6, the mass concentration of QSPIB-M solution is 10%, 17 The mass concentration of the dispersion is 10%.

10. Use of the polyacid covalently cross-linked aromatic proton exchange membrane according to any one of claims 1 to 2, characterized in that: As a proton exchange membrane in fuel cells.

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