A sulfonated polyimide containing alkyne groups, a preparation method thereof, and a method for preparing a cross-linked proton exchange membrane using the same

Abstract

A sulfonated polyimide containing alkyne groups, a preparation method, and a method for preparing a cross-linked proton exchange membrane using the same belong to the technical field of polymer materials and fuel cell materials. The alkyne cross-linked sulfonated polyimide in the present invention is prepared by polycondensation and cross-linking reaction of an aromatic diamine monomer containing alkyne groups, a sulfonated diamine monomer, and 1,4,5,8-naphthalenetetracarboxylic acid dianhydride. The polymerized monomer used in the present invention has a relatively rigid molecular structure and does not contain an ether bond, which gives the proton exchange membrane more excellent mechanical properties, dimensional stability, and chemical stability. Alkyne cross-linked polyimide has a unique three-dimensional configuration, which is conducive to proton transport. The hydrophobic segment containing trifluoromethyl and the hydrophilic segment in the cross-linked sulfonated polyimide form a hydrophilic-hydrophobic phase separation morphology, which promotes the formation of a proton transport channel. Therefore, the alkyne cross-linked sulfonated polyimide proton exchange membrane prepared by the present invention has high proton conductivity, excellent mechanical properties and stability.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and fuel cell materials, and particularly relates to an alkyne-containing sulfonated polyimide for fuel cells, a preparation method thereof, and a method for preparing a cross-linked proton exchange membrane using the same. Background Art

[0002] Fuel cells can directly convert chemical energy in fuel into electrical energy. They have the advantages of high energy conversion rate, strong modularity and green environmental protection. Therefore, they have attracted much attention as a new type of clean energy device with great application potential. Membrane Electrode Assembly (MEA) is a key component of proton exchange membrane fuel cells (PEMFC). MEA is the place for multiphase material transmission and electrochemical reaction in the energy conversion process. During the operation of the fuel cell, MEA involves three-phase interface reaction and complex mass transfer and heat transfer process. Therefore, MEA directly determines the performance, life and cost of PEMFC. The structure of MEA mainly includes proton exchange membrane (PEM), gas diffusion layer and catalyst layer. PEM in MEA plays the role of providing transmission channel for proton transmission and blocking fuel and oxidant, which has an important influence on the performance of MEA and the entire fuel cell.

[0003] Currently, the commercial proton exchange membrane for fuel cells is a perfluorosulfonic acid proton exchange membrane, which has excellent chemical and mechanical stability and high proton conductivity. However, the high fuel permeability often leads to a decrease in its performance during battery operation. In addition, the low glass transition temperature and complex synthesis process also limit its further application. Sulfonated polyimide has excellent mechanical properties, outstanding heat resistance, chemical stability and low fuel permeability, and has been widely studied in recent years. Due to the rigid aromatic skeleton structure, it is difficult to form a continuous hydrophilic-hydrophobic phase separation structure in the sulfonated polyimide membrane. Therefore, the proton transport capacity of the sulfonated polyimide is usually enhanced by increasing the degree of sulfonation. However, a high degree of sulfonation will also lead to a decrease in water absorption, dimensional stability, alcohol resistance, etc., which seriously affects the potential of sulfonated polyimide in practical applications.

[0004] Yao Hongyan et al. (CN 105418921A) invented two diamine monomers containing crosslinkable tetrafluorostyrene groups, 2,2-bis[3-amino-4-(2,3,5,6-tetrafluoro-4-vinylphenoxy)phenyl]hexafluoropropane and 3,3'-bis(2,3,5,6-tetrafluoro-4-vinylphenoxy)-4,4'-biphenylenediamine, and used these two diamine monomers to synthesize a new type of crosslinkable sulfonated polyimide and a crosslinked sulfonated proton exchange membrane. The crosslinked sulfonated polyimide proton exchange membrane disclosed in the patent has high proton conductivity, moderate water absorption and swelling rate, and excellent stability. However, the molecular structure and proton conductivity properties of the crosslinked sulfonated polyimide can still be further optimized and improved, but there are no relevant reports at present.

[0005] Therefore, a new technical solution is urgently needed in the prior art to solve this problem. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an alkyne-containing sulfonated polyimide and a preparation method thereof, and a method for preparing a cross-linked proton exchange membrane using the same, so as to solve the technical problem of further optimizing the molecular structure and performance of the cross-linked sulfonated polyimide.

[0007] A sulfonated polyimide containing an alkyne group has the following structure:

[0008] ;

[0009] Among them, the value range of x is 0.4~0.9, the value range of y is 0.1~0.6, and x+y=1; n≥10; Ar is an aromatic group.

[0010] The Ar is selected from any one of the following structures:

[0011] The first one:

[0012] ;

[0013] Second type:

[0014] ;

[0015] The third type:

[0016] ;

[0017] Correspondingly, the alkynyl-containing sulfonated polyimide polymers are:

[0018] ;

[0019] ;

[0020] ;

[0021] Among them, n≥10.

[0022] A method for preparing an alkyne-containing sulfonated polyimide, for preparing the alkyne-containing sulfonated polyimide, comprises the following steps, and the following steps are performed in sequence:

[0023] Step 1, under an inert gas environment, dissolve the sulfonated diamine monomer and triethylamine in an organic solvent, add 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)-2,2,2-trifluoroethane, 1,4,5,8-naphthalenetetracarboxylic dianhydride and benzoic acid, stir, heat to 60°C to 100°C for reaction for 3h to 6h, then heat to 180°C to 220°C for reaction for 12h to 24h, then cool to 60°C to 100°C and add the organic solvent to dilute the polymer solution concentration to 1 / 2 to 1 / 5 of the original to obtain a polymer solution;

[0024] Step 2: Dispose the polymer solution in acetone, extract with acetone, and dry to obtain the alkyne-containing sulfonated polyimide polymer.

[0025] The inert gas is nitrogen or argon.

[0026] The sulfonated diamine monomer is selected from any one of the following structures:

[0027] The first one:

[0028] ;

[0029] Second type:

[0030] ;

[0031] The third type:

[0032] .

[0033] The molar ratio of the sulfonated diamine monomer, 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)2,2,2-trifluoroethane, 1,4,5,8-naphthalenetetracarboxylic dianhydride, benzoic acid and triethylamine is (0.4-0.9):(0.1-0.6):(1.0):(1.0-1.4):(0.8-2.0).

[0034] The organic solvent is m-cresol.

[0035] The usage amount of the acetone is 2 to 4 times that of the meta-cresol.

[0036] A method for preparing a cross-linked proton exchange membrane using the alkyne-containing sulfonated polyimide comprises the following steps, which are performed in sequence:

[0037] Step 1: placing a glass plate in an oven, preparing a polymer solution with a concentration of 0.05-0.2 g / mL by mixing alkynyl-containing sulfonated polyimide and dimethyl sulfoxide, and pouring the filtered filtrate onto the cleaned glass plate;

[0038] Step 2: adjusting the oven temperature to perform programmed temperature rise to remove the dimethyl sulfoxide solvent, wherein the programmed temperature rise is: 80°C for 2 h, 100°C for 2 h, 120°C for 2 h under normal pressure, and 120°C for 8 h under vacuum to obtain an alkyne-containing sulfonated polyimide membrane;

[0039] Step 3: placing the alkyne-containing sulfonated polyimide in a high-temperature oven, subjecting it to a heat treatment at 250° C. to 300° C. for 2 h to 6 h, cooling it to room temperature, and then taking the obtained cross-linked film out of the high-temperature oven;

[0040] Step 4: Acidify the cross-linked membrane with dilute sulfuric acid or dilute hydrochloric acid, and finally obtain an alkyne-cross-linked sulfonated polyimide proton exchange membrane in the form of sulfonic acid, which is the cross-linked proton exchange membrane.

[0041] The concentration of the dilute sulfuric acid or dilute hydrochloric acid is 0.5~2 ML -1 .

[0042] Through the above design scheme, the present invention can bring the following beneficial effects:

[0043] The alkynyl cross-linked sulfonated polyimide in the present invention is prepared by polycondensation and cross-linking reaction of alkynyl-containing aromatic diamine monomer 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)2,2,2-trifluoroethane, sulfonated diamine monomer and 1,4,5,8-naphthalenetetracarboxylic dianhydride. The polymerized monomer used in the present invention has a relatively rigid molecular structure and does not contain ether bonds, which can give the polymer a rigid molecular skeleton. Its stable chemical structure can give the proton exchange membrane better mechanical properties, dimensional stability and chemical stability. The 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)2,2,2-trifluoroethane monomer used in the present invention has a three-dimensional structure, an alkynyl group capable of undergoing a cross-linking reaction, and a hydrophobic trifluoromethyl group. The three-dimensional structure of the monomer and the formation of the cross-linking structure give the alkynyl cross-linked polyimide a unique three-dimensional configuration, which is conducive to the transmission of protons. The hydrophobic segments containing trifluoromethyl groups aggregate after the cross-linking reaction, and form a hydrophilic-hydrophobic phase separation morphology with the hydrophilic segments in the cross-linked sulfonated polyimide, thereby promoting the formation of proton transport channels. Therefore, the alkyne-cross-linked sulfonated polyimide proton exchange membrane prepared by the present invention can have high proton conductivity, excellent mechanical properties and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present invention is further described below with reference to the accompanying drawings and specific embodiments:

[0045] Figure 1 is a TGA thermogravimetric curve of the alkynyl cross-linked sulfonated polyimide proton exchange membrane prepared in Example 6 of the present invention;

[0046] Figure 2 This is a graph of the proton conductivity of the alkynyl cross-linked sulfonated polyimide proton exchange membrane prepared in Example 6 of the present invention. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present invention are described clearly and completely below. The described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. For greater clarity, the following embodiments are described in detail below.

[0048] Example 1

[0049] This embodiment provides an alkyne-containing sulfonated polyimide, a preparation method thereof, and a method for preparing a cross-linked proton exchange membrane using the same.

[0050] (1) Preparation of sulfonated polyimide containing alkyne groups

[0051] Under an inert gas environment, 1.6938 g of 2,5-diaminobenzenesulfonic acid and 1.0119 g of triethylamine were dissolved in 32 mL of m-cresol, 0.3664 g of 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)2,2,2-trifluoroethane, 2.6818 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 1.2212 g of benzoic acid were added and stirred evenly, the mixture was heated to 60 °C for 6 h, and then 220 °C for 18 h. The mixture was then cooled to 60 °C and 30 mL of m-cresol was added to dilute the obtained polymer solution. The polymer solution was taken out of 300 mL of acetone, extracted with acetone, and dried to obtain the polymer product:

[0052] .

[0053] (2) Cross-linked proton exchange membrane

[0054] Alkyne-containing sulfonated polyimide and dimethyl sulfoxide were prepared into a polymer solution with a concentration of 0.05 g / mL. The filtered solution was poured onto a cleaned glass plate and dried at 80 °C for 10 h and 120 °C for 24 h to remove the solvent to obtain an alkyne-containing sulfonated polyimide membrane. The alkyne-containing sulfonated polyimide was placed in a high-temperature oven and heat treated at 250 °C for 6 h. After the temperature was lowered to room temperature, it was acidified with 1 mol / L dilute hydrochloric acid for 16 h, and finally an alkyne-crosslinked sulfonated polyimide proton exchange membrane was obtained. The test results of the proton exchange membrane are shown in the following table: .

[0055] Example 2

[0056] This embodiment provides an alkyne-containing sulfonated polyimide, a preparation method thereof, and a method for preparing a cross-linked proton exchange membrane using the same.

[0057] (1) Preparation of sulfonated polyimide containing alkyne groups

[0058] Under an inert gas environment, 2.0662 g of 2,2'-benzidine disulfonic acid and 1.6190 g of triethylamine were dissolved in 41 mL of m-cresol, 1.4656 g of 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)2,2,2-trifluoroethane, 2.6818 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 1.5876 g of benzoic acid were added and stirred evenly, the mixture was heated to 60 °C for reaction for 3 h, 180 °C for reaction for 24 h, then cooled to 60 °C and 40 mL of m-cresol was added to dilute the obtained polymer solution, the polymer solution was taken out of 400 mL of acetone, extracted with acetone and dried to obtain the polymer product:

[0059] .

[0060] (2) Cross-linked proton exchange membrane

[0061] Alkyne-containing sulfonated polyimide and dimethyl sulfoxide were prepared into a polymer solution with a concentration of 0.1 g / mL. The filtered solution was poured onto a cleaned glass plate and dried at 80 °C for 10 h and 120 °C for 24 h to remove the solvent to obtain an alkyne-containing sulfonated polyimide membrane. The alkyne-containing sulfonated polyimide was placed in a high-temperature oven and heat treated at 270 °C for 4 h. After the temperature was lowered to room temperature, it was acidified with 1 mol / L dilute hydrochloric acid for 16 h, and finally an alkyne-crosslinked sulfonated polyimide proton exchange membrane was obtained. The test results of the proton exchange membrane are shown in the following table: .

[0062] Example 3

[0063] This embodiment provides an alkyne-containing sulfonated polyimide, a preparation method thereof, and a method for preparing a cross-linked proton exchange membrane using the same.

[0064] (1) Preparation of sulfonated polyimide containing alkyne groups

[0065] Under an inert gas (nitrogen, argon) environment, 2.7549 g of 2,2'-benzidine disulfonic acid and 2.0238 g of triethylamine were dissolved in 41 mL of m-cresol, 0.7328 g of 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)2,2,2-trifluoroethane, 2.6818 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 1.7097 g of benzoic acid were added and stirred evenly, the temperature was raised to 90 °C for reaction for 3 h, and 220 °C for reaction for 18 h, then the temperature was lowered to 60 °C and 40 mL of m-cresol was added to dilute the obtained polymer solution, the polymer solution was taken out of 400 mL of acetone, extracted with acetone, and dried to obtain the polymer product:

[0066] .

[0067] (2) Cross-linked proton exchange membrane

[0068] Alkyne-containing sulfonated polyimide and dimethyl sulfoxide were prepared into a polymer solution with a concentration of 0.1 g / mL. The filtered solution was poured onto a cleaned glass plate and dried at 80 °C for 10 h and 120 °C for 24 h to remove the solvent to obtain an alkyne-containing sulfonated polyimide membrane. The alkyne-containing sulfonated polyimide was placed in a high-temperature oven and heat treated at 300 °C for 2 h. After the temperature was lowered to room temperature, it was acidified with 1 mol / L dilute hydrochloric acid for 16 h, and finally an alkyne-crosslinked sulfonated polyimide proton exchange membrane was obtained. The test results of the proton exchange membrane are shown in the following table: .

[0069] Example 4

[0070] This embodiment provides an alkyne-containing sulfonated polyimide, a preparation method thereof, and a method for preparing a cross-linked proton exchange membrane using the same.

[0071] (1) Preparation of sulfonated polyimide containing alkyne groups

[0072] Under an inert gas (nitrogen, argon) environment, 1.4816 g of 4,4'-diaminostilbene-2,2'-disulfonic acid and 1.0119 g of triethylamine were dissolved in 42 mL of m-cresol, 2.1983 g of 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)2,2,2-trifluoroethane, 2.6818 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 1.4654 g of benzoic acid were added and stirred evenly, the mixture was heated to 60 °C for 6 h, and then 180 °C for 24 h. The mixture was then cooled to 60 °C and 40 mL of m-cresol was added to dilute the obtained polymer solution. The polymer solution was taken out of 400 mL of acetone, extracted with acetone, and dried to obtain the polymer product:

[0073] .

[0074] (2) Cross-linked proton exchange membrane

[0075] Alkyne-containing sulfonated polyimide and dimethyl sulfoxide were prepared into a polymer solution with a concentration of 0.05 g / mL. The filtered solution was poured onto a cleaned glass plate and dried at 80 °C for 10 h and 120 °C for 24 h to remove the solvent to obtain an alkyne-containing sulfonated polyimide membrane. The alkyne-containing sulfonated polyimide was placed in a high-temperature oven and heat treated at 250 °C for 6 h. After the temperature was lowered to room temperature, it was acidified with 1 mol / L dilute hydrochloric acid for 16 h, and finally an alkyne-crosslinked sulfonated polyimide proton exchange membrane was obtained. The test results of the proton exchange membrane are shown in the following table: .

[0076] Example 5

[0077] This embodiment provides an alkyne-containing sulfonated polyimide, a preparation method thereof, and a method for preparing a cross-linked proton exchange membrane using the same.

[0078] (1) Preparation of sulfonated polyimide containing alkyne groups

[0079] Under an inert gas (nitrogen, argon) environment, 2.2224 g of 4,4'-diaminostilbene-2,2'-disulfonic acid and 1.4167 g of triethylamine were dissolved in 43 mL of m-cresol, 1.4656 g of 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)2,2,2-trifluoroethane, 2.6818 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 1.5876 g of benzoic acid were added and stirred evenly, the mixture was heated to 70 °C for 5 h, and then 220 °C for 12 h, then cooled to 80 °C and 40 mL of m-cresol was added to dilute the obtained polymer solution, the polymer solution was taken out of 400 mL of acetone, extracted with acetone, and dried to obtain the polymer product:

[0080] .

[0081] (2) Cross-linked proton exchange membrane

[0082] Alkyne-containing sulfonated polyimide and dimethyl sulfoxide were prepared into a polymer solution with a concentration of 0.1 g / mL. The filtered solution was poured onto a cleaned glass plate and dried at 80 °C for 10 h and 120 °C for 24 h to remove the solvent to obtain an alkyne-containing sulfonated polyimide membrane. The alkyne-containing sulfonated polyimide was placed in a high-temperature oven and heat treated at 270 °C for 4 h. After the temperature was lowered to room temperature, it was acidified with 1 mol / L dilute hydrochloric acid for 16 h, and finally an alkyne-crosslinked sulfonated polyimide proton exchange membrane was obtained. The test results of the proton exchange membrane are shown in the following table: .

[0083] Example 6

[0084] This embodiment provides an alkyne-containing sulfonated polyimide, a preparation method thereof, and a method for preparing a cross-linked proton exchange membrane using the same.

[0085] (1) Preparation of sulfonated polyimide containing alkyne groups

[0086] Under an inert gas (nitrogen, argon) environment, 2.9632 g of 4,4'-diaminostilbene-2,2'-disulfonic acid and 1.8214 g of triethylamine were dissolved in 43 mL of m-cresol, 0.7328 g of 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)2,2,2-trifluoroethane, 2.6818 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 1.7097 g of benzoic acid were added and stirred evenly, the temperature was raised to 90 °C for reaction for 3 h, and then 220 °C for reaction for 18 h, then the temperature was lowered to 100 °C and 40 mL of m-cresol was added to dilute the obtained polymer solution, the polymer solution was taken out of 400 mL of acetone, extracted with acetone, and dried to obtain the polymer product:

[0087] .

[0088] (2) Cross-linked proton exchange membrane

[0089] Alkyne-containing sulfonated polyimide and dimethyl sulfoxide were prepared into a polymer solution with a concentration of 0.2 g / mL. The filtered solution was poured onto a cleaned glass plate and dried at 80 °C for 10 h and 120 °C for 24 h to remove the solvent to obtain an alkyne-containing sulfonated polyimide membrane. The alkyne-containing sulfonated polyimide was placed in a high-temperature oven and heat treated at 300 °C for 2 h. After the temperature was lowered to room temperature, it was acidified with 1 mol / L dilute hydrochloric acid for 16 h, and finally an alkyne-crosslinked sulfonated polyimide proton exchange membrane was obtained. The test results of the proton exchange membrane are shown in the following table: .

[0090] It can be seen that the alkyne-crosslinked sulfonated polyimide proton exchange membrane prepared in the present invention has excellent film-forming properties, and the membrane material has excellent mechanical properties and flexibility.

[0091] Figure 1 This is a TGA thermogravimetric curve of the alkynyl cross-linked sulfonated polyimide of Example 6, indicating that the alkynyl cross-linked sulfonated polyimide proton exchange membrane prepared by the present invention has excellent thermal stability.

[0092] Figure 2 This is the proton conductivity diagram of Example 6. From the data of proton conductivity variation with temperature, it can be seen that the proton conductivity of the alkynyl cross-linked sulfonated polyimide proton exchange membrane increases with increasing temperature, and exhibits higher proton conductivity at both room temperature and 80°C, which has good application advantages in fuel cells.

[0093] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, 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, they should be considered to be within the scope of this specification.

[0094] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An alkyne-containing sulfonated polyimide, characterized in that: Its structure as follows: ； Wherein, the value range of x is 0.4~0.9, the value range of y is 0.1~0.6, and x+y=1; n≥10; Ar is an aromatic group; The Ar is selected from any one of the following structures: The first one: ； Second type: ； The third type: ； Correspondingly, the alkynyl-containing sulfonated polyimide polymers are: ； ； 。 2. A method for preparing an alkyne-containing sulfonated polyimide, for preparing an alkyne-containing sulfonated polyimide according to claim 1, characterized in that: The process includes the following steps, which are performed in sequence: Step 1, under an inert gas environment, dissolve the sulfonated diamine monomer and triethylamine in an organic solvent, add 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)-2,2,2-trifluoroethane, 1,4,5,8-naphthalenetetracarboxylic dianhydride and benzoic acid, stir, heat to 60°C to 100°C for reaction for 3h to 6h, then heat to 180°C to 220°C for reaction for 12h to 24h, then cool to 60°C to 100°C and add the organic solvent to dilute the polymer solution concentration to 1 / 2 to 1 / 5 of the original to obtain a polymer solution; Step 2, discharging the polymer solution in acetone, extracting with acetone, and drying to obtain an alkyne-containing sulfonated polyimide polymer; The sulfonated diamine monomer is selected from any one of the following structures: The first one: ； Second type: ； The third type: 。 3. The method for preparing an alkyne-containing sulfonated polyimide according to claim 2, characterized in that: The inert gas is nitrogen or argon.

4. The method for preparing an alkyne-containing sulfonated polyimide according to claim 2, wherein: The molar ratio of the sulfonated diamine monomer, 1,1-bis(4-aminophenyl)-1-1(4-ethynylphenyl)2,2,2-trifluoroethane, 1,4,5,8-naphthalenetetracarboxylic dianhydride, benzoic acid and triethylamine is (0.4-0.9):(0.1-0.6):(1.0):(1.0-1.4):(0.8-2.0).

5. The method for preparing an alkyne-containing sulfonated polyimide according to claim 2, characterized in that: The organic solvent is m-cresol.

6. The method for preparing an alkyne-containing sulfonated polyimide according to claim 5, characterized in that: The usage amount of the acetone is 2 to 4 times that of the meta-cresol.

7. A method for preparing a cross-linked proton exchange membrane using the alkyne-containing sulfonated polyimide according to claim 1, characterized in that: Includes the following step, And the following steps are performed in sequence: Step 1: placing a glass plate in an oven, preparing a polymer solution with a concentration of 0.05-0.2 g / mL by mixing alkynyl-containing sulfonated polyimide and dimethyl sulfoxide, and pouring the filtered filtrate onto the cleaned glass plate; Step 2: adjusting the oven temperature to perform programmed temperature rise to remove the dimethyl sulfoxide solvent, wherein the programmed temperature rise is: 80°C for 2 h, 100°C for 2 h, 120°C for 2 h, and vacuum at 120°C for 8 h, to obtain an alkyne-containing sulfonated polyimide membrane; Step 3: placing the alkyne-containing sulfonated polyimide in a high-temperature oven, subjecting it to a heat treatment at 250°C to 300°C for 2h to 6h, cooling it to room temperature, and then taking the obtained cross-linked film out of the high-temperature oven; Step 4: Acidify the cross-linked membrane with dilute sulfuric acid or dilute hydrochloric acid, and finally obtain an alkyne-cross-linked sulfonated polyimide proton exchange membrane in the form of sulfonic acid, which is the cross-linked proton exchange membrane.

8. A method for preparing a cross-linked proton exchange membrane using the alkyne-containing sulfonated polyimide according to claim 1 according to claim 7, characterized in that: The concentration of the dilute sulfuric acid or dilute hydrochloric acid is 0.5-2 mol·L -1 .

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