Preparation method and application of IL-MOF modified OPBI type high-temperature proton exchange membrane

Abstract

The invention discloses a preparation method and application of an IL-MOF modified OPBI type high-temperature proton exchange membrane, and belongs to the field of proton exchange membranes. The proton exchange membrane comprises an ionic liquid containing hexafluorophosphoric acid anions which are easy to form hydrogen bonds and an MOF (Metal Organic Framework) nanostructure which is used as a skeleton support. The IL is selected from 1-ethyl 3-methylimidazolium hexafluorophosphate and 1-aminoethyl-3-methylimidazolium hexafluorophosphate, and the IL is selected from 1-ethyl 3-methylimidazolium hexafluorophosphate; and the MOF is selected from a group consisting of ZIF-8 and ZIF-90. The specific preparation method mainly comprises the following steps: adding MOF powder and an ionic liquid into an OPBI polymer solution, uniformly stirring and mixing the MOF powder and the ionic liquid, casting the MOF powder and the ionic liquid onto a glass plate, and volatilizing a solvent at a certain temperature to obtain the IL-MOF modified polybenzimidazole high-temperature proton exchange membrane. The preparation method disclosed by the invention is simple and efficient, and the prepared proton exchange membrane has excellent proton conduction capability and also has good dimensional stability and mechanical strength.

Description

Technical Field

[0001] The present invention belongs to the field of proton exchange membranes, and particularly relates to a preparation method and application of a high-temperature proton exchange membrane of polybenzimidazole modified by IL-MOF materials. Background Art

[0002] Fuel cells based on hydrogen energy are currently considered one of the effective technical solutions for achieving energy security, reliability, efficiency, and sustainable development. Proton exchange membrane fuel cells (PEMFCs) are one of the core application scenarios of hydrogen energy, and have the advantages of high energy conversion efficiency, zero emissions and zero pollution, high power density, quiet operation, and fast cold start. It is expected to replace the currently commonly used energy conversion devices and become an ideal candidate power source for distributed power stations, vehicle power supplies, and mobile power supplies, with very high commercial value. The proton exchange membrane (PEM) is the core component of PEMFCs, which plays a role in proton conduction, isolating electrons, fuels, and oxidants in the battery. Its performance largely determines the performance of fuel cells. High-performance PEMs generally should have the following characteristics: high proton conductivity, high resistance to fuel permeability, high oxidation stability, good mechanical stability, and excellent durability.

[0003] Currently, a typical PEM is a perfluorosulfonic acid (PFSA) membrane, and the Nafion membrane produced by DuPont in the United States is the most prominent representative among PFSA membranes. The proton transfer of the Nafion membrane depends on water molecules. The greater the water content in the membrane, the higher the proton conductivity. However, the Nafion membrane has some problems, such as the operating temperature is limited to medium and low temperatures, and it must work under humidified conditions. After long-term operation, the fuel permeability is relatively high, thus reducing the power density of the battery. The operating temperature range of high-temperature proton exchange membrane fuel cells (HT-PEMFCs) is between 100 and 200 °C. Compared with LT-PEMFCs, HT-PEMFCs have the advantages of improving the tolerance of Pt catalysts to CO, accelerating the electrode reaction kinetics, and simplifying the water and heat management system. Developing various new types of high-temperature resistant PEM materials has become one of the research hotspots for the development of PEMFCs.

[0004] Polybenzimidazole (PBI) polymers are engineering plastics with a rigid main-chain structure and have become a key research object for high-temperature proton exchange membranes due to their excellent properties such as high mechanical strength, good thermal stability, chemical stability, and oxidation stability. The phosphoric acid (PA)-doped high-temperature proton exchange membrane is essentially an acid-base composite membrane, that is, the alkaline / weakly alkaline polymer macromolecular chains provide phosphoric acid adsorption sites (such as imine, amide, imidazole groups, etc.) and provide the mechanical properties of the membrane material. Proton conduction in the PA-PBI membrane mainly follows the hopping mechanism, and protons hop and transfer in the hydrogen bond network in the PA-PBI membrane. Under the condition of high temperature without humidification, the proton transfer of PA-PBI-based high-temperature proton exchange membranes mainly depends on the doping level of phosphoric acid.

[0005] In the present invention, ionic liquid (IL) and metal-organic framework (MOF) are used as proton conductors and introduced into the OPBI polymer solution containing flexible ether bonds. By encapsulating IL into the nanostructure of the MOF material, the imidazole groups in IL provide hopping sites for proton transport, and MOF serves as a framework support. In addition, compared with the unmodified membrane, this composite membrane exhibits excellent proton conductivity and good mechanical properties. Summary of the Invention

[0006] The key technical problem to be solved by the present invention is to provide a preparation method of an IL-MOF modified polybenzimidazole-based high-temperature proton exchange membrane and its application in high-temperature proton exchange membrane fuel cells.

[0007] The present invention provides an IL-MOF modified polybenzimidazole-based high-temperature proton exchange membrane, characterized in that the proton exchange membrane comprises a modifier and a polybenzimidazole polymer; wherein the modifier comprises an ionic liquid (IL) containing an acidic imidazole group and a hexafluorophosphate anion that is easy to form hydrogen bonds, and an MOF nanostructure serving as a framework support.

[0008] The IL is selected from 1-ethyl-3-methylimidazolium hexafluorophosphate and 1-aminoethyl-3-methylimidazolium hexafluorophosphate; the MOF is selected from zeolitic imidazolate framework-8 (ZIF-8) and zeolitic imidazole framework-90 (ZIF-90).

[0009] Furthermore, the polybenzimidazole is selected from OPBI polymers.

[0010] The addition amount of MOF is 4-12 wt% of the total amount of the proton exchange membrane, and the addition amount of the IL is 10-50 wt% of the total amount of the proton exchange membrane;

[0011] The present invention provides a preparation method of the above-mentioned IL-MOF modified polybenzimidazole-based high-temperature proton exchange membrane, comprising the following steps:

[0012] Step a: Weigh accurately a certain amount of polybenzimidazole polymer powder and dissolve it in an organic solvent to obtain a polymer solution with a certain concentration.

[0013] Step b: Weigh accurately a certain amount of the metal salt corresponding to the MOF and the organic ligand corresponding to the MOF material, dissolve them separately in appropriate solvents, then mix the two, react under certain conditions, and perform centrifugation, washing, and drying to obtain MOF powder.

[0014] Step c: Add the MOF powder prepared in Step b to a certain amount of the polymer solution obtained in Step a. After stirring and mixing evenly to form a transparent solution, add IL thereto, and stir under certain conditions to obtain a uniform and transparent casting solution.

[0015] Step d: Pour the casting solution obtained in Step c evenly onto a clean glass plate, and after the solvent evaporates at a certain heating temperature, an IL-MOF modified polybenzimidazole high-temperature proton exchange membrane is obtained.

[0016] Specifically, the organic solvent described in Step a is selected from one or more of N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone, and the concentration of the polymer solution is 4-12 wt%.

[0017] Specifically, the metal salt corresponding in Step b is a zinc salt, selected from one or more of zinc nitrate hexahydrate and zinc acetate; the organic ligand is selected from one or more of 2-methylimidazole and imidazole-2-carbaldehyde; the solvent is one or more of water, N,N-dimethylformamide, N,N-dimethylformamide, ethylene glycol, methanol, and ethanol; the synthesis temperature is 40-120 °C; the reaction time is 0.5-6 h.

[0018] Specifically, the MOF described in Step c is selected from one or more of the reaction products ZIF-8 and ZIF-90 in Step b; the IL is selected from one or more of 1-ethyl-3-methylimidazolium hexafluorophosphate and 1-aminoethyl-3-methylimidazolium hexafluorophosphate; the stirring time is 6-24 h.

[0019] Specifically, the thickness of the cast film described in Step d is 30-70 μm; the heating temperature is 60-200 °C, preferably 80-150 °C; the heating time is 18-36 h.

[0020] An IL-MOF modified polybenzimidazole high-temperature proton exchange membrane of the present invention is used in an H2 / O2 high-temperature fuel cell to obtain a proton exchange membrane with excellent proton conductivity and mechanical properties.

[0021] The beneficial effects brought by the technical solution provided by the present invention are as follows: The IL-MOF modified polybenzimidazole-based high-temperature proton exchange membrane prepared by the present invention contains imidazole groups, hexafluorophosphate anions and MOF nanostructures, which can improve the phosphoric acid doping amount of the membrane while maintaining good mechanical properties. On the one hand, cations containing imidazole groups and IL with hexafluorophosphate anions are considered to be introduced, so that it has proton transfer characteristics of basic groups (acidophilic groups) to increase the capture sites for phosphoric acid. Thus, IL can be used as a non-aqueous proton conductor to improve the proton conductivity while reducing the loss of PA. On the other hand, considering enhancing the mechanical properties of the membrane, since MOF has an adjustable framework structure and rich active sites, it can not only serve as the skeleton support of the membrane but also encapsulate IL inside, achieving the purpose of improving the proton conductivity and mechanical properties of the membrane. Compared with the unmodified polybenzimidazole membrane, the IL-MOF modified polybenzimidazole-based high-temperature proton exchange membrane (especially the composite modification of ZIF-8 and 1-ethyl-3-methylimidazolium hexafluorophosphate) can increase the proton conductivity by 2.5 - 4 times without affecting its mechanical strength, indicating that the addition of IL-MOF significantly promotes the proton conduction performance of the membrane. Brief Description of the Drawings

[0022] Figure 1 . SEM images of the surface and cross-section of the IL / ZIF-8 / OPBI composite membrane prepared in Example 1 of the present invention.

[0023] Figure 2 . SEM images of the surface and cross-section of the IL / ZIF-90 / OPBI composite membrane prepared in Example 2 of the present invention.

[0024] Figure 3 . SEM images of the surface and cross-section of the IL-NH2 / ZIF-8 / OPBI composite membrane prepared in Example 3 of the present invention.

[0025] Figure 4 . SEM images of the surface and cross-section of the IL-NH2 / ZIF-90 / OPBI composite membrane prepared in Example 1 of the present invention. Detailed Description of the Invention

[0026] To make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0027] The present invention provides an IL-MOF modified polybenzimidazole-based high-temperature proton exchange membrane, which includes acidophilic imidazole groups, hexafluorophosphate anions that are easy to form hydrogen bonds, and MOF nanostructures as the skeleton support.

[0028] The ILs described above are selected from 1-ethyl-3-methylimidazolium hexafluorophosphate and 1-aminoethyl-3-methylimidazolium hexafluorophosphate; the MOFs are selected from zeolitic imidazolate framework-8 (ZIF-8) and zeolitic imidazole framework-90 (ZIF-90).

[0029] An embodiment of the present invention provides a method for preparing the above IL-MOF modified polybenzimidazole high-temperature proton exchange membrane, including:

[0030] Step 101: Accurately weigh a certain amount of OPBI polymer powder and dissolve it in an organic solvent to obtain a polymer solution with a certain concentration.

[0031] Step 102: Accurately weigh a certain amount of zinc metal salt and organic ligand, dissolve them separately in appropriate solvents, then mix the two, react under certain conditions, and centrifuge, wash, and dry to obtain MOF powder.

[0032] Step 103: Add the MOF powder prepared in Step 102 to a certain amount of OPBI polymer solution. After stirring and mixing evenly to form a transparent solution, add IL thereto, and stir under certain conditions to obtain a uniformly transparent casting solution.

[0033] Step 104: Pour the casting solution obtained in Step 103 evenly onto a clean glass plate, and after the solvent evaporates at a certain temperature, the IL-MOF modified polybenzimidazole high-temperature proton exchange membrane is obtained.

[0034] Specifically, the organic solvent described in Step 101 is selected from one or more of N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone, preferably N,N-dimethylacetamide, and the concentration of OPBI is 4-12 wt%, specifically 4 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt%.

[0035] Specifically, the zinc metal salt described in Step 102 is selected from one or more of zinc nitrate hexahydrate and zinc acetate; the organic ligand is selected from one or more of 2-methylimidazole and imidazole-2-carboxaldehyde; the organic solvent is one or more of water, N,N-dimethylformamide, N,N-dimethylformamide, ethylene glycol, methanol, and ethanol; the dissolution temperature of the zinc metal salt is 30-60 °C; the dissolution temperature of the organic ligand is 40-80 °C; the reaction temperature is 40-120 °C, specifically 30 °C, 60 °C, 80 °C, 100 °C, 120 °C; the reaction time is 0.5-6 h.

[0036] Specifically, the MOF in step 103 is selected from one or more of the reaction products ZIF-8 and ZIF-90 in step 102, preferably ZIF-8; the IL is selected from one or more of 1-ethyl-3-methylimidazolium hexafluorophosphate and 1-aminoethyl-3-methylimidazolium hexafluorophosphate, preferably 1-ethyl-3-methylimidazolium hexafluorophosphate; the MOF addition amount is 4-12wt% of the total amount of the proton exchange membrane, specifically 4wt%, 6wt%, 8wt%, 10wt%, and 12wt%; the IL addition amount is 10-50wt% of the total amount of the proton exchange membrane, specifically 10wt%, 20wt%, 30wt%, 40wt%, and 50wt%; the stirring time is 6-24h;

[0037] Specifically, the thickness of the casting film in step d is 30-70 μm; the heating temperature is 60-200° C., preferably 80-150° C.; and the heating time is 18-36 hours.

[0038] The present invention will be further described below through specific examples.

[0039] In the following specific examples, the operations involved, if the conditions are not specified, were carried out according to conventional conditions or the conditions recommended by the manufacturer. The raw materials used, if the manufacturer and specifications are not specified, are all conventional products that can be obtained through commercial purchase.

[0040] Example 1

[0041] Step (1) 1.8 g of OPBI polymer powder was accurately weighed and dissolved in 28.2 g of N,N-dimethylacetamide to obtain a 6 wt% OPBI polymer solution. 0.585 g of zinc nitrate hexahydrate and 11.35 g of 2-methylimidazole were accurately weighed and dissolved in 4 mL and 40 mL of deionized water, respectively. The mixture was stirred until dissolved, and the mixture was mixed and stirred at room temperature for 30 min. The mixture was washed three times by centrifugation with methanol and then dried at 80°C overnight to obtain white powder ZIF-8.

[0042] Step (2) Accurately weigh 15 mg of ZIF-8 prepared in step (1) and 100 mg of 1-ethyl-3-methylimidazolium hexafluorophosphate, add them to 2 g of the OPBI polymer solution in step (1), ultrasonicate at room temperature for 1 hour, and stir for 18 hours to thoroughly mix. The resulting homogeneous solution is cast onto a clean glass plate, dried at 80°C for 24 hours, and then dried at 150°C for 2 hours. The film is peeled off the glass plate to obtain an IL / ZIF-8 / OPBI composite membrane with a thickness of 50-60 μm.

[0043] After doping the prepared IL / ZIF-8 / OPBI composite membrane with phosphoric acid, the proton conductivity performance was tested by the four-electrode method. The test conditions were 60 - 180 °C.

[0044] The proton conductivity of the phosphoric acid-doped IL / ZIF-8 / OPBI composite membrane was measured to be 0.236 S·cm -1 @120 °C, 0.243 S·cm -1 @140 °C, 0.252 S·cm -1 @160 °C and 0.260 S·cm -1 @180 °C.

[0045] After doping the prepared IL / ZIF-8 / OPBI composite membrane with phosphoric acid, the tensile strength was tested. The test conditions were 2 mm·min -1 .

[0046] The tensile strength of the phosphoric acid-doped IL / ZIF-8 / OPBI composite membrane was measured to be 7.45 MPa.

[0047] Example 2

[0048] Step (1): Accurately weigh 1.8 g of OPBI polymer powder and dissolve it in 28.2 g of N,N-dimethylacetamide to obtain an OPBI polymer solution with a mass concentration of 6 wt%. Accurately weigh 0.845 g of imidazole-2-carboxaldehyde and 0.483 g of zinc acetate, dissolve them separately in 30 mL of N,N-dimethylformamide solution, and after stirring until dissolved, mix the two, stir at room temperature for 6 h, wash by centrifugation 3 times with N,N-dimethylformamide and methanol respectively, and then dry overnight at 80 °C to obtain a brown powder ZIF-90.

[0049] Step (2): Accurately weigh 15 mg of the ZIF-90 prepared in step (1) and 100 mg of 1-ethyl-3-methylimidazolium hexafluorophosphate, add them to the 2 g of OPBI polymer solution in step (1), ultrasonicate for 1 h at room temperature, stir for 18 h to mix them well. Pour the obtained homogeneous solution onto a clean glass plate, dry at 80 °C for 24 h, and then dry at 150 °C for 2 h. Peel the film off the glass plate to obtain an IL / ZIF-90 / OPBI composite membrane with a thickness of 50 - 60 μm.

[0050] After doping the prepared IL / ZIF-90 / OPBI composite membrane with phosphoric acid, the proton conductivity performance was tested by the four-electrode method. The test conditions were 60 - 180 °C.

[0051] The proton conductivity of the phosphoric acid-doped IL / ZIF-90 / OPBI composite membrane was measured to be 0.048 S·cm -1@120℃、0.052S·cm -1 @140℃、0.056S·cm -1 @160℃ and 0.057S·cm -1 @180℃.

[0052] The prepared IL / ZIF-90 / OPBI composite membrane was doped with phosphoric acid and then subjected to tensile strength test. The test conditions were: 2 mm min -1 .

[0053] The tensile strength of the phosphoric acid-doped IL / ZIF-90 / OPBI composite membrane was measured to be 6.23 MPa.

[0054] Example 3

[0055] Step (1) 1.8 g of OPBI polymer powder was accurately weighed and dissolved in 28.2 g of N,N-dimethylacetamide to obtain a 6 wt% OPBI polymer solution. 0.585 g of zinc nitrate hexahydrate and 11.35 g of 2-methylimidazole were accurately weighed and dissolved in 4 mL and 40 mL of deionized water, respectively. The mixture was stirred until dissolved, and the mixture was mixed and stirred at room temperature for 30 min. The mixture was washed three times by centrifugation with methanol and then dried at 80°C overnight to obtain white powder ZIF-8.

[0056] Step (2) Accurately weigh 15 mg of ZIF-8 prepared in step (1) and 100 mg of 1-aminoethyl-3-methylimidazolium hexafluorophosphate, add them to 2 g of the OPBI polymer solution in step (1), ultrasonicate at room temperature for 1 hour, and stir for 18 hours to thoroughly mix. The resulting homogeneous solution is cast onto a clean glass plate, dried at 80°C for 24 hours, and then dried at 150°C for 2 hours. The film is peeled off the glass plate to obtain an IL-NH2 / ZIF-8 / OPBI composite membrane with a thickness of 50-60 μm.

[0057] The prepared IL-NH2 / ZIF-8 / OPBI composite membrane was doped with phosphoric acid and then the proton conductivity performance was tested using the four-electrode method under the test conditions of 60-180°C.

[0058] The proton conductivity of the phosphoric acid-doped IL-NH2 / ZIF-8 / OPBI composite membrane was measured to be 0.075 S·cm -1 @120℃、0.084S·cm -1 @140℃、0.090S·cm -1 @160℃ and 0.094S·cm -1 @180℃.

[0059] The prepared IL-NH2 / ZIF-8 / OPBI composite membrane was doped with phosphoric acid and then subjected to a tensile strength test. Test conditions: 2 mm·min -1 。

[0060] The measured tensile strength of the phosphoric acid-doped IL-NH2 / ZIF-8 / OPBI composite membrane was 6.71 MPa.

[0061] Example 4

[0062] Step (1) Accurately weigh 1.8 g of OPBI polymer powder and dissolve it in 28.2 g of N,N-dimethylacetamide to obtain an OPBI polymer solution with a mass concentration of 6 wt%. Accurately weigh 0.845 g of imidazole-2-carbaldehyde and 0.483 g of zinc acetate, dissolve them separately in 30 mL of N,N-dimethylformamide solution, and after stirring until dissolved, mix the two, stir at room temperature for 6 h, centrifuge and wash three times with N,N-dimethylformamide and methanol respectively, and then dry overnight at 80 °C to obtain a brown powder ZIF-90.

[0063] Step (2) Accurately weigh 15 mg of ZIF-90 prepared in step (1) and 100 mg of 1-aminoethyl-3-methylimidazolium hexafluorophosphate, add them to the 2 g of OPBI polymer solution in step (1), ultrasonicate for 1 h at room temperature, and stir for 18 h to mix them thoroughly. Pour the obtained uniform solution onto a clean glass plate, dry at 80 °C for 24 h, and then dry at 150 °C for 2 h. Peel the film from the glass plate to obtain an IL-NH2 / ZIF-90 / OPBI composite membrane with a thickness of 50 - 60 μm.

[0064] The prepared IL-NH2 / ZIF-90 / OPBI composite membrane was doped with phosphoric acid and then subjected to a proton conductivity performance test using the four-electrode method. Test conditions: 60 - 180 °C.

[0065] The measured proton conductivity of the phosphoric acid-doped IL-NH2 / ZIF-90 / OPBI composite membrane was 0.041 S·cm -1 @120 °C, 0.042 S·cm -1 @140 °C, 0.043 S·cm -1 @160 °C and 0.046 S·cm -1 @180 °C.

[0066] The prepared IL-NH2 / ZIF-90 / OPBI composite membrane was doped with phosphoric acid and then subjected to a tensile strength test. Test conditions: 2 mm·min -1 。

[0067] The tensile strength of the phosphoric acid-doped IL-NH2 / ZIF-90 / OPBI composite membrane was measured to be 6.86 MPa.

[0068] The above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An IL-MOF modified polybenzimidazole-based high-temperature proton exchange membrane, characterized in that, The proton exchange membrane includes a modifier and a polybenzimidazole polymer; wherein the modifier includes an ionic liquid (IL) containing an acidic imidazole group and a hexafluorophosphate anion that is prone to form hydrogen bonds, and a MOF nanostructure as a framework support; The IL is selected from 1-ethyl-3-methylimidazolium hexafluorophosphate and 1-aminoethyl-3-methylimidazolium hexafluorophosphate; the MOF is selected from zeolitic imidazolate framework-8 (ZIF-8) and zeolitic imidazole framework-90 (ZIF-90).

2. An IL-MOF modified polybenzimidazole-based high-temperature proton exchange membrane according to claim 1, wherein The polybenzimidazole is selected from OPBI polymers.

3. An IL-MOF modified polybenzimidazole-based high-temperature proton exchange membrane according to claim 1 or 2, characterized in that, The addition amount of the MOF is 4-12 wt% of the total amount of the proton exchange membrane, and the addition amount of the IL is 10-50 wt% of the total amount of the proton exchange membrane.

4. A method for preparing the IL-MOF modified polybenzimidazole-based high-temperature proton exchange membrane according to any one of claims 1-3, characterized in that, It includes the following steps: Step a, accurately weigh a certain amount of polybenzimidazole polymer powder, dissolve it in an organic solvent to obtain a polymer solution with a certain concentration; Step b, accurately weigh a certain amount of the metal salt corresponding to the MOF and the organic ligand corresponding to the MOF material, dissolve them separately in appropriate solvents, then mix the two, react under certain conditions, centrifuge, wash and dry to obtain MOF powder; Step c, add the MOF powder prepared in step b to a certain amount of the polymer solution obtained in step a. After stirring and mixing evenly to form a transparent solution, then add IL, and stir under certain conditions to obtain a uniformly transparent casting solution; Step d, uniformly cast the casting solution obtained in step c onto a clean glass plate, and after the solvent evaporates at a certain heating temperature, an IL-MOF modified polybenzimidazole high-temperature proton exchange membrane is obtained.

5. The method according to claim 4, characterized in that, The organic solvent described in step a is selected from one or more of N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone, and the concentration of the polymer solution is 4-12 wt%.

6. The method according to claim 4, wherein The metal salt corresponding in step b is a zinc salt, selected from one or more of zinc nitrate hexahydrate and zinc acetate; the organic ligand is selected from one or more of 2-methylimidazole and imidazole-2-carboxaldehyde; the solvent is one or more of water, N,N-dimethylformamide, N,N-dimethylformamide, ethylene glycol, methanol, and ethanol; the synthesis temperature is 40-120 °C; the reaction time is 0.5-6 h.

7. The method according to claim 4, characterized in that The thickness of the cast film described in step d is 30-70 μm; the heating temperature is 60-200 °C, preferably 80-150 °C; the heating time is 18-36 h.

8. Application of the polybenzimidazole high-temperature proton exchange membrane according to any one of claims 1-3, used in an H2 / O2 high-temperature fuel cell to obtain a proton exchange membrane with excellent proton conductivity and mechanical properties.

9. According to the application described in claim 8, the operating temperature range of the H2 / O2 high-temperature fuel cell is 60-180 °C.

10. A H2 / O2 high-temperature fuel cell, characterized in that, Adopt the polybenzimidazole high-temperature proton exchange membrane according to any one of claims 1-3.

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