CN112510236B - Proton exchange membrane and preparation method and application thereof - Google Patents

Abstract

The present invention provides a proton exchange membrane, a preparation method and application thereof. The proton exchange membrane comprises a covalent organic framework material and an ionic polymer compounded with the covalent organic framework material. The proton exchange membrane provided by the present invention has the characteristics of good proton conductivity, proton conductivity stability and mechanical properties, and can improve the energy conversion rate and service life of the fuel cell. The above-mentioned proton exchange membrane has the advantages of simple preparation process, low cost, green environmental protection and the like, and has important practical significance in the industry.

Description

Proton exchange membrane and preparation method and application thereof

technical field

The invention relates to a proton exchange membrane, a preparation method and application thereof, and belongs to the field of fuel cells.

Background technique

Proton exchange membranes (PEMs), as the core components of proton exchange membrane fuel cells (PEMFCs), play an important role in the operation of fuel cells. An ideal PEM is expected to have high proton conductivity and excellent mechanical properties.

Covalent organic frameworks (COFs) are a class of crystalline porous materials that are generated mainly by covalent bonds linking lighter elements (such as BCN0) in a periodic manner due to their chemical tunability, high porosity, and ordered Features such as structural integrity have received widespread attention. Membrane materials based on COF have been studied and reported. For example, Sasmal et al. (Angew. Chem. Int. Ed. 2018, 57, 10894.) disclosed a COF-based membrane material, which is mainly in situ in COF. Small molecule proton carriers are loaded for proton conduction; there are also membrane materials that incorporate polymers in COF, for example, Xie et al. Alcohol (PEG), through the synergistic effect of PEG and water, improves the proton conductivity to a certain extent.

Although COF can be used as a matrix or raw material for membrane materials such as proton exchange membranes, on the one hand, due to the high crystallinity of COF, the mechanical properties of conventional membrane materials are poor, mainly in terms of brittleness and easy cracking. , In order to meet the performance requirements of the proton exchange membrane, such as the conductivity and other performance requirements, the proton carrier (such as p-toluenesulfonic acid, etc.) and other components are usually introduced into the COF. Affect the properties of proton exchange membranes such as proton transport efficiency.

SUMMARY OF THE INVENTION

In view of the above-mentioned defects of the prior art, the present invention provides a proton exchange membrane, which has both good proton conductivity and proton conductivity stability, as well as good mechanical properties and other characteristics.

The present invention also provides a preparation method of a proton exchange membrane, which can prepare the above proton exchange membrane, and has the advantages of simple preparation process, low cost, environmental protection and the like.

The present invention also provides an application of the above-mentioned proton exchange membrane in a fuel cell. The application of the above-mentioned proton exchange membrane to a fuel cell can improve the energy conversion rate, service life and other qualities of the fuel cell.

One aspect of the present invention provides a proton exchange membrane comprising a covalent organic framework material and an ionic polymer compounded with the covalent organic framework material.

The proton exchange membrane provided by the present invention has both good proton conductivity, proton conductivity stability and mechanical properties. The inventor believes that the introduction of the ionic polymer into the COF matrix is equivalent to the introduction of the band into the COF matrix. The cationic groups and anionic groups construct acid-base ion pairs, and the ionic polymer is filled in the pores of the COF as a proton carrier. The synergistic cooperation of the two can significantly improve the proton conductivity and stability of the proton exchange membrane. At the same time, the introduction of the ionic polymer into the COF as a high polymer further ensures the mechanical properties of the proton exchange membrane, making it difficult to break. , with good performance and long service life.

According to the research of the present invention, the above-mentioned covalent organic framework materials can generally include ketoenamine materials obtained by reacting diamino monomers and aldehyde monomers with Schiff bases, which is beneficial to further improve the proton conductivity of the proton exchange membrane. and mechanical properties.

During specific implementation, the moles of diamino monomers are generally greater than the moles of aldehyde-based monomers, and in a preferred embodiment, the molar ratio of diamino-based monomers to aldehyde-based monomers can be 1.2-1.5: 1.

Specifically, the above-mentioned diamino-based monomers may include p-phenylenediamine (hereinafter referred to as Pa-1), 2,5-diaminobenzenesulfonic acid (hereinafter referred to as Pa-SO ₃ H), 1,4-disulfonic acid Acid-2,5-diaminobenzene (hereinafter referred to as Pa-(SO ₃ H) ₂ ), 4,4'-diaminobiphenyl (hereinafter referred to as Bd), benzidine disulfonic acid (hereinafter referred to as Bd- (SO ₃ H) ₂ ), 1,4-diaminopyridine (hereinafter referred to as Py), at least one of 4,4'-diamino-2,2'-bipyridine (hereinafter referred to as BPy); further Typically, the aldehyde-based monomer includes 2,4,6-trihydroxy-1,3,5-benzenetricarbaldehyde (hereinafter referred to as Tp). The use of COF synthesized from such monomers is beneficial to further improve the proton conductivity and mechanical properties of the proton exchange membrane. It is presumed that the reason is that the use of the above-mentioned diamino monomers with sulfonic acid or pyridine groups and aldehydes The COF synthesized from the base-type monomer is beneficial to introduce acidic or basic ionic groups into the COF, which further enhances its interaction with the ionic polymer, thereby improving the performance of the proton exchange membrane.

Further, the use of an ionic polymer with a sulfonic acid group or an imine group, or a quaternary ammonium salt ionic polymer is more conducive to the performance of the proton exchange membrane. In a preferred embodiment of the present invention, the above The ionic polymer may include at least one of poly(4-styrenesulfonic acid) (PSS), polyethyleneimine (PEI), polydiallyldimethylammonium chloride (PDDA).

Further, the weight average molecular weight of the above-mentioned ionic polymer may generally be 70,000-500,000.

After further research, the introduction of ionic polymers into COF through an in-situ loading process is more conducive to the proton conductivity and mechanical properties of the proton exchange membrane. Specifically, in a preferred embodiment of the present invention, the above proton exchange membrane It can be prepared according to the preparation process including the following steps: the wet film formed by coating the slurry containing the covalent organic framework material synthetic monomer and the ionic polymer is subjected to a Schiff base reaction to obtain the proton exchange membrane; wherein, Synthetic monomers include diamino-based monomers and aldehyde-based monomers.

In another aspect of the present invention, there is also provided a method for preparing a proton exchange membrane, comprising: subjecting a wet film formed by coating a slurry containing a covalent organic framework material synthetic monomer and an ionic polymer to a Schiff base reaction, The proton exchange membrane is obtained; wherein, the synthetic monomers include diamino-based monomers and aldehyde-based monomers.

In specific implementation, synthetic monomers such as amino-based monomers and aldehyde-based monomers can be ground and mixed first, and ionic polymer and water are added to the obtained mixed powder, and the slurry is formed after grinding and mixing. Wherein, the amount of water added satisfies the above-mentioned components to be mixed to form a slurry state. During the specific operation, the mixture powder and the aqueous solution of the ionic polymer can be mixed to form a slurry, and the slurry can also be adjusted by adding an appropriate amount of water. concentration to make it easier to coat into a film.

In general, it also includes defoaming treatment of the above-mentioned slurry, for example, it can be placed in a vacuum box for vacuuming to remove possible air bubbles (i.e. defoaming treatment), and then coated to form a wet film.

Specifically, the mass ratio of the above-mentioned ionic polymer to the synthetic monomer of the covalent organic framework material can be (1-15):100.

In order to be more conducive to the progress of the reaction, the above slurry may also include a catalyst, and the molar ratio of the catalyst to the synthesis monomer may be (2-5):1.

Further, the above catalyst may include p-toluenesulfonic acid (PTSA). According to the research of the present application, the introduction of p-toluenesulfonic acid in the above preparation process can further improve the properties of the proton exchange membrane, such as the proton conductivity. In the pores of the COF, new proton transport sites are provided, thereby improving the proton transport capacity of the proton exchange membrane. In the specific operation, p-toluenesulfonic acid monohydrate (PTSA·H ₂ O) is usually used as a catalyst.

In a preferred embodiment of the present invention, the amino-based monomers and p-toluenesulfonic acid can generally be mixed and ground into powder, and then the aldehyde-based monomers are added to the powder, and the grinding and mixing are continued. The ionic polymer and water are added to the powder to form the above-mentioned slurry, which is more conducive to subsequent processing and the preparation of a proton exchange membrane with excellent properties such as proton conductivity.

In the present invention, conventional methods in the art can be used to coat the above-mentioned slurry into a wet film. Placed in a mold to form a wet film or the like, which is not particularly limited.

In the above-mentioned preparation process, when the Schiff base reaction is carried out, the stage heating reaction can generally be carried out. In a preferred embodiment of the present invention, the process of the above-mentioned Schiff base reaction comprises: under normal pressure conditions (that is, the pressure is 1 atm) conditions), the above wet membrane was reacted at 50-60°C for 12-24h, then heated to 80-90°C for 12-24h, and then heated to 105-120°C for 12-24h to obtain a proton exchange membrane.

After the above-mentioned Schiff base reaction is completed, the obtained membrane product can be washed with solvents such as dichloromethane (DCM) and acetone to remove possible impurities such as unreacted monomers and oligomers, and remove them from the mold or substrate. The proton exchange membrane is obtained by removing it up and down, and drying it again, wherein the drying temperature can be 40±5°C.

In yet another aspect of the present invention, an application of the above proton exchange membrane in a fuel cell is also provided.

The implementation of the present invention has at least the following beneficial effects:

The proton exchange membrane provided by the present invention is a new type of COF-based proton exchange membrane, which has good proton conductivity and proton conductivity stability, and at the same time has high mechanical strength, is not easy to break, and has a long service life, and has important industrial applications. practical significance.

In the preparation method of the proton exchange membrane provided by the present invention, the above-mentioned proton exchange membrane is synthesized in situ, so that it has the characteristics of good proton conductivity, proton conductivity stability and mechanical properties, and the preparation process is simple, the conditions are mild, and there is no need for The use of a large amount of organic solvents has the advantages of low cost, green environmental protection and practical industrial production and application.

The proton exchange membrane fuel cell provided by the present invention adopts the above proton exchange membrane and has the advantages of high energy conversion rate and long service life.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the present invention. examples, but not all examples. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work, all belong to the protection scope of the present invention.

Example 1

The proton exchange membrane provided in this embodiment is prepared according to the following process:

(1) Add 56.5 mg (0.3 mmol) Pa-SO ₃ H and 285 mg (1.5 mmol) PTSA·H ₂ O into a mortar, grind and mix uniformly, then add 42 mg (0.2 mmol) Tp, and further grind uniformly to obtain a mixture powder;

(2) Add 98.5 mg of PDDA aqueous solution with a mass concentration of 1% and 202 μl of deionized water to the above mixture powder, grind and mix evenly to form a mixed slurry; place the mixed slurry in a vacuum box and vacuumize at room temperature After the pressure is 0.5 bar, it is kept for 5 minutes to degas the mixed slurry; wherein, the weight-average molecular weight of PDDA is 450,000;

(3) Use a film applicator with a thickness of 250 μm to evenly coat the degassed mixed slurry on the glass plate to form a wet film with a thickness of 250 μm;

(4) Put the glass plate in an oven, first keep it at 60°C for 12h, then heat it up to 90°C for 12h, and then heat it up to 120°C for 12h; soak the obtained film-like product together with the glass plate in DCM for 30min , then peeled off the film-like product from the glass plate, washed with DCM and acetone in turn, and dried at 40° C. for 8 h to obtain a proton exchange membrane.

Example 2

(1) Add 80.5 mg (0.3 mmol) Pa-(SO ₃ H) ₂ and 285.3 mg (1.5 mmol) PTSA·H ₂ O into a mortar, grind and mix well, then add 42 mg (0.2 mmol) Tp, and grind further Homogeneous to obtain a mixture powder;

(2) Add 184 mg of PDDA aqueous solution with a mass concentration of 10% and 216 μl of deionized water to the above mixture powder, grind and mix evenly to form a mixed slurry; place the mixed slurry in a vacuum box, and evacuated at room temperature to After the pressure is 0.5 bar, it is kept for 5 minutes to degas the mixed slurry; wherein, the weight-average molecular weight of PDDA is 500,000;

(3) Use a film applicator with a thickness of 250 μm to evenly coat the degassed mixed slurry on the glass plate to form a wet film with a thickness of 250 μm;

(4) Put the glass plate in an oven, first keep it at 60°C for 12h, then heat it up to 80°C for 12h, and then heat it up to 120°C for 12h; soak the obtained film-like product together with the glass plate in DCM for 30min , then peeled off the film-like product from the glass plate, washed with DCM and acetone in turn, and dried at 40° C. for 8 h to obtain a proton exchange membrane.

Example 3

(1) Add 103.3 mg (0.3 mmol) of Bd-(SO ₃ H) ₂ and 285.3 mg (1.5 mmol) of PTSA·H ₂ O into a mortar, grind and mix well, then add 42 mg (0.2 mmol) of Tp, and grind further Homogeneous to obtain a mixture powder;

(2) Add 72.5 mg of PEI aqueous solution with a mass concentration of 10% and 427 μl of deionized water to the above mixture powder, grind and mix evenly to form a mixed slurry; place the mixed slurry in a vacuum box and vacuumize at room temperature After the pressure is 0.5 bar, keep it for 5 minutes to degas the mixed slurry; wherein, the weight-average molecular weight of PEI is 180,000;

(3) Use a film applicator with a thickness of 250 μm to evenly coat the degassed mixed slurry on the glass plate to form a wet film with a thickness of 250 μm;

(4) Put the glass plate in an oven, keep it at 60°C for 12h, then heat it up to 90°C for 12h, and then heat it up to 105°C for 12h; soak the obtained film-like product together with the glass plate in DCM for 30min , then peeled off the film-like product from the glass plate, washed with DCM and acetone in turn, and dried at 40° C. for 8 h to obtain a proton exchange membrane.

Example 4

(1) 32.7 mg (0.3 mmol) Py and 476 mg (2.5 mmol) PTSA·H ₂ O were added to a mortar, ground and mixed uniformly, then 42 mg (0.2 mmol) Tp was added, and further ground was uniformly obtained to obtain a mixture powder;

(2) Add 104.6 mg of PSS aqueous solution with a mass concentration of 5% and 395 μl of deionized water to the above mixture powder, grind and mix evenly to form a mixed slurry; place the mixed slurry in a vacuum box and vacuumize at room temperature After the pressure is 0.5 bar, it is kept for 5 minutes to defoam the mixed slurry; wherein, the PSS weight-average molecular weight is 70,000;

(3) Use a film applicator with a thickness of 250 μm to evenly coat the degassed mixed slurry on the glass plate to form a wet film with a thickness of 250 μm;

(4) Put the glass plate in an oven, keep it at 50°C for 12h, then heat it up to 90°C for 12h, and then heat it up to 120°C for 12h; soak the obtained film-like product together with the glass plate in DCM for 30min , then peeled off the film-like product from the glass plate, washed with DCM and acetone in turn, and dried at 40° C. for 8 h to obtain a proton exchange membrane.

Example 5

(1) 55.9 mg (0.3 mmol) BPy and 380 mg (2 mmol) PTSA·H ₂ O were added to the mortar, ground and mixed uniformly, then 42 mg (0.2 mmol) Tp was added, and further ground was uniformly obtained to obtain a mixture powder;

(2) Add 98 mg of PSS aqueous solution with a mass concentration of 10% and 402 μl of deionized water to the above mixture powder, grind and mix evenly to form a mixed slurry; put the mixed slurry in a vacuum box, and vacuumize it at room temperature to After the pressure is 0.5 bar, it is kept for 5 minutes to degas the mixed slurry; wherein, the weight-average molecular weight of PSS is 70,000;

(3) Use a film applicator with a thickness of 250 μm to evenly coat the degassed mixed slurry on the glass plate to form a wet film with a thickness of 250 μm;

(4) Put the glass plate in an oven, first keep it at 60°C for 12h, then heat it up to 85°C for 12h, and then heat it up to 110°C for 12h; soak the obtained film-like product together with the glass plate in DCM for 30min Then, the film-like product was peeled off from the glass plate, washed with DCM and acetone in turn, and dried at 40° C. for 8 h to obtain a proton exchange membrane.

Example 6

(1) 32.4 mg (0.3 mmol) Pa-1 and 190 mg (1 mmol) PTSA·H ₂ O were added to the mortar, ground and mixed uniformly, then 42 mg (0.2 mmol) Tp was added, and further ground was uniformly obtained to obtain a mixture powder;

(2) Add 37 mg of PSS aqueous solution with a mass concentration of 10%, 37 mg of PDDA aqueous solution with a mass concentration of 10% and 50 μl of deionized water to the above mixture powder, grind and mix evenly to form a mixed slurry; place the mixed slurry in a vacuum In the box, evacuated to a pressure of 0.5 bar at room temperature and kept for 5 minutes to degas the mixed slurry; wherein, the weight-average molecular weight of PSS was 70,000, and the weight-average molecular weight of PDDA was 100,000;

(3) Use a film applicator with a thickness of 250 μm to evenly coat the degassed mixed slurry on the glass plate to form a wet film with a thickness of 250 μm;

(4) Put the glass plate in an oven, keep it at 55°C for 12h, then heat it up to 90°C for 12h, and then heat it up to 115°C for 12h; soak the obtained film-like product together with the glass plate in DCM for 30min , then peeled off the film-like product from the glass plate, washed with DCM and acetone in turn, and dried at 40° C. for 8 h to obtain a proton exchange membrane.

Example 7

(1) 55.2 mg (0.3 mmol) Bd and 190 mg (1 mmol) PTSA·H ₂ O were added to a mortar, ground and mixed uniformly, then 42 mg (0.2 mmol) Tp was added, and further ground was uniformly obtained to obtain a mixture powder;

(2) adding 73 mg of PSS aqueous solution with a mass concentration of 10%, 73 mg of an aqueous PDDA solution with a mass concentration of 10% and 20 μl of deionized water to the above-mentioned mixture powder, grinding and mixing evenly to form a mixed slurry; the mixed slurry is placed in a vacuum In the box, evacuated to a pressure of 0.5 bar at room temperature and kept for 5 minutes to degas the mixed slurry; wherein, the weight-average molecular weight of PSS was 70,000, and the weight-average molecular weight of PDDA was 100,000;

(3) Use a film applicator with a thickness of 250 μm to evenly coat the degassed mixed slurry on the glass plate to form a wet film with a thickness of 250 μm;

(4) Put the glass plate in an oven, keep it at 60°C for 12h, then heat it up to 90°C for 12h, and then heat it up to 115°C for 12h; soak the obtained film-like product together with the glass plate in DCM for 30min , then peeled off the film-like product from the glass plate, washed with DCM and acetone in turn, and dried at 40° C. for 8 h to obtain a proton exchange membrane.

Comparative Example 1

(1) Add 56.5 mg (0.3 mmol) Pa-SO ₃ H and 285 mg (1.5 mmol) PTSA·H ₂ O into a mortar, grind and mix uniformly, then add 42 mg (0.2 mmol) Tp, and further grind uniformly to obtain a mixture powder;

(2) Add 500 μl of deionized water to the above mixture powder, grind and mix evenly to form a mixed slurry; place the mixed slurry in a vacuum box, vacuumize it to a pressure of 0.5 bar at room temperature, and keep it for 5 minutes to prevent The mixed slurry is defoamed;

(3) Use a film applicator with a thickness of 250 μm to evenly coat the degassed mixed slurry on the glass plate to form a wet film with a thickness of 250 μm;

(4) Put the glass plate in an oven, first keep it at 60°C for 12h, then heat it up to 90°C for 12h, and then heat it up to 120°C for 12h; soak the obtained film-like product together with the glass plate in DCM for 30min , then peeled off the film-like product from the glass plate, washed with DCM and acetone in turn, and dried at 40° C. for 8 h to obtain a proton exchange membrane.

Comparative Example 2

(1) Add 32.4 mg (0.3 mmol) Pa-1 and 190 mg (1.0 mmol) PTSA·H ₂ O into a mortar, grind and mix uniformly, then add 42 mg (0.2 mmol) Tp, and further grind uniformly to obtain a mixture powder;

(2) Add 500 μl of deionized water to the above mixture powder, grind and mix evenly to form a mixed slurry; put the mixed slurry in a vacuum box, and vacuumize it at room temperature to a pressure of 0.5 bar and keep it for 5 minutes to prevent The mixed slurry is defoamed;

(3) Use a film applicator with a thickness of 250 μm to evenly coat the degassed mixed slurry on the glass plate to form a wet film with a thickness of 250 μm;

(4) Put the glass plate in an oven, keep it at 60°C for 12h, then heat it up to 90°C for 12h, and then heat it up to 115°C for 12h; soak the obtained film-like product together with the glass plate in DCM for 30min , then peeled off the film-like product from the glass plate, washed with DCM and acetone in turn, and dried at 40° C. for 8 h to obtain a proton exchange membrane.

Performance Testing:

The proton conductivity of the proton exchange membranes of each example and the comparative example was measured according to the following procedure: the proton exchange membrane was placed on two parallel platinum sheets, and the proton exchange membrane was tested in pure water at 60°C using an electrochemical workstation (CHI660E). The AC impedance of , the frequency range is 10Hz to 10MHz, and the test environment is 100% RH; and the proton conductivity is calculated by the following formula: σ=L/(R·A), where σ(S/cm) represents the proton conductivity, L (cm) represents the distance between the two electrodes, R (Ω) represents the impedance value of the proton exchange membrane, and A (cm ₂ ) represents the cross-sectional area of the proton exchange membrane sample.

According to the above-mentioned test process, after the proton exchange membrane was tested for the first time, it was soaked in deionized water at room temperature for 7 days, and then the proton conductivity of the proton exchange membrane was tested again according to the above-mentioned test process to verify the loss of proton carriers.

The initial test proton conductivity of the proton exchange membranes of each embodiment and the comparative example, and the proton conductivity after soaking for 7 days are shown in Table 1.

In addition, the proton exchange membranes of the examples and comparative examples were bent as much as possible to observe whether they were broken to verify their mechanical properties. The results are shown in Table 1.

Table 1 Performance measurement results of the proton exchange membranes of Examples 1-7 and Comparative Examples 1-2

It can be seen from Table 1 that, compared with Comparative Examples 1 and 2, the proton exchange membranes of Examples 1-7 have very excellent proton conductivity, and after 7 days of immersion, the proton conductivity of the membranes decreases very little, indicating Example 1 The proton carrier in the proton exchange membrane of -7 is not easy to be lost, and has strong proton conductivity stability. At the same time, the proton exchange membrane of Example 1-7 does not break after bending, and also shows good mechanical properties.

While the invention has been described with reference to specific embodiments, those skilled in the art will appreciate that various changes can be made without departing from the true spirit and scope of the invention. In addition, many changes may be made to adapt a particular situation, material, composition of materials and method to the body, spirit and scope of the invention. All such changes are included within the scope of the claims of the present invention.

Claims (5)

1. A proton exchange membrane, which is characterized by comprising a covalent organic framework material and an ionic polymer compounded with the covalent organic framework material, wherein the proton exchange membrane is prepared by the following steps: coating slurry containing covalent organic framework material synthetic monomers, ionic polymers and p-toluenesulfonic acid to form a wet membrane, and carrying out Schiff base reaction to obtain the proton exchange membrane;

wherein the ionic polymer comprises at least one of poly (4-styrenesulfonic acid), polyethyleneimine and polydiallyldimethylammonium chloride; the synthetic monomer comprises a diamino monomer and an aldehyde monomer, wherein the diamino monomer comprises at least one of p-phenylenediamine, 2, 5-diaminobenzene sulfonic acid, 1, 4-disulfonic acid-2, 5-diaminobenzene, 4 '-diaminobiphenyl, benzidine disulfonic acid, 1, 4-diaminopyridine, 4' -diamino-2, 2 '-bipyridyl, p-phenylenediamine and 4,4' -diaminobiphenyl; the aldehyde group monomer comprises 2,4, 6-trihydroxy-1, 3, 5-benzenetricarboxylic acid;

the mass ratio of the ionic polymer to the synthetic monomer of the covalent organic framework material is (1-15): 100, respectively; the molar ratio of the p-toluenesulfonic acid to the synthetic monomer is (2-5): 1.

2. the proton exchange membrane according to claim 1, wherein the weight average molecular weight of the ionic polymer is 70000 to 500000.

3. The process for the preparation of a proton exchange membrane according to claim 1 or 2, comprising: coating slurry containing covalent organic framework material synthetic monomers, ionic polymers and p-toluenesulfonic acid to form a wet membrane, and carrying out Schiff base reaction to obtain the proton exchange membrane; wherein the synthetic monomer comprises a diamino monomer and an aldehyde monomer; the mass ratio of the ionic polymer to the synthetic monomer of the covalent organic framework material is (1-15): 100, respectively; the molar ratio of the p-toluenesulfonic acid to the synthetic monomer is (2-5): 1.

4. the method for preparing the Schiff base, according to claim 3, wherein the Schiff base reaction process comprises the following steps: under the condition of normal pressure, the wet membrane reacts for 12-24h at 50-60 ℃, then is heated to 80-90 ℃ for reaction for 12-24h, and then is heated to 105-120 ℃ for reaction for 12-24h, so as to obtain the proton exchange membrane.

5. Use of a proton exchange membrane according to claim 1 or 2 in a fuel cell.