Preparation method of SPEEK / COF-PE composite proton exchange membrane material and proton exchange membrane fuel cell thereof

Abstract

This invention relates to the field of new energy materials and fuel cell technology, specifically to a method for preparing a SPEEK / COF-PE composite proton exchange membrane material and its application. By combining sulfonated polyether ether ketone (PE) with a covalent organic framework material (COF-PE), a multi-level proton conduction channel and hydrogen bond network are constructed. This approach combines the film-forming properties of SPEEK with the pore structure characteristics of COF-PE, resulting in a significant simultaneous improvement in the material's proton conductivity, mechanical strength, and chemical stability. When applied to fuel cell proton conduction, this material exhibits high proton conductivity, high tensile strength, and strong chemical stability. This invention addresses the performance shortcomings of traditional non-fluorinated proton exchange membranes, overcomes the environmental and cost limitations of fluorinated proton exchange membranes, and achieves a balance between proton conduction performance and overall stability. It has practical significance in promoting the industrialization of non-fluorinated proton exchange membranes and adapting them for hydrogen fuel cell applications in new energy vehicles, portable power supplies, and other scenarios.

Description

Technical Field

[0001] This invention belongs to the field of proton exchange membrane material preparation and fuel cell technology, specifically involving a method for preparing a SPEEK / COF-PE composite proton exchange membrane and its application in proton conduction within fuel cells. By combining sulfonated polyether ether ketone (SPEEK) with a COF-PE covalent organic framework material, a multi-level proton conduction channel and hydrogen bond network are constructed, improving proton conductivity, mechanical strength, and chemical stability. This composite membrane can serve as a core proton exchange membrane component for fuel cells, addressing the performance shortcomings of traditional proton exchange membranes and is suitable for applications such as hydrogen fuel cells, portable power supplies, and new energy transportation vehicles. Background Technology

[0002] This invention relates to the field of new energy materials and fuel cell technology, and particularly to a SPEEK / COF-PE composite proton exchange membrane material. It addresses the problems of existing fluorine-based proton exchange membranes, which are costly and prone to causing environmental fluorine pollution, and whose materials cannot simultaneously meet the requirements of high proton conductivity, excellent mechanical strength, and chemical stability for fuel cells. Pure SPEEK proton exchange membranes suffer from discontinuous proton conduction channels, high swelling ratio, and poor chemical stability, while COF-PE materials are difficult to form into films and cannot be directly applied.

[0003] The purpose of this invention is to provide a method for preparing a SPEEK / COF-PE composite proton-conducting material. This material combines the proton-conducting properties of sulfonated polyether ether ketone (SPEEK) with the pore-regulating advantages of the COF-PE covalent organic framework, exhibiting excellent proton conductivity and serving as a core functional material for fluorine-free proton exchange membranes in fuel cells. Fuel cells, as clean power generation devices that directly convert chemical energy into electrical energy, have become an important direction for replacing traditional fossil fuels due to their high energy conversion efficiency, zero emissions, and low noise, and are widely used in automobiles, distributed power generation, mobile devices, and other fields. The proton exchange membrane is the core component of a fuel cell; its proton conductivity, chemical stability, and mechanical strength directly determine the cell's output efficiency and lifespan. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a SPEEK / COF-PE composite proton-conducting material. The SPEEK / COF-PE composite proton-conducting material integrates sulfonated polyether ether ketone (SPEEK) and COF-PE. It exhibits excellent proton conductivity and can serve as a core functional material for fluorine-free proton exchange membranes in fuel cells. The preparation method of the SPEEK / COF-PE composite proton-conducting material includes the following steps:

[0005] (1) Preparation of COF-PE: (a) Add 2,5-dihydroxyterephthalic acid to ethanol, then add concentrated sulfuric acid, and heat the mixture to react, yielding ethyl 2,5-dihydroxyterephthalate.

[0006] (b) Take a certain amount of ethyl 2,5-dihydroxyterephthalate and potassium carbonate, dissolve them in anhydrous acetonitrile and react under an inert gas protection. After the reaction is completed, cool, add diethyl phosphate (3-bromopropyl) 4-acetylmethyl ether and react for a period of time. After the reaction is completed, process to obtain a yellow oily substance. React the yellow oily substance with anhydrous ethanol and hydrazine hydrate solution to obtain 1,4-bis(4-diethoxyphosphorylbutoxy)-2,5-dihydroxybenzene-3,6-dicarboxyhydrazide.

[0007] (c) A certain amount of 1,4-bis(4-diethoxyphosphorylbutoxy)-2,5-dihydroxybenzene-3,6-dicarboxylhydrazine and mesenthalpyraldehyde were dissolved in a certain amount of mesenthalpyrene solution, and the solution was placed in an ampoule and baked in an oven. After baking, the solution was purified in tetrahydrofuran by Soxhlet extraction and then dried in an oven to obtain the product COF-PE.

[0008] (2) Preparation of SPPEK: PEEK powder was added to concentrated sulfuric acid for reaction. After the reaction was complete, the SPEEK was continuously rinsed until the rinsing water was neutral. Finally, the mixture was dried. (3) Preparation of SPPEK / COF-PE: Dissolve a certain amount of SPEEK in (2) in dimethyl sulfoxide solution, then add a certain amount of COF-PE material in (1) and stir for a period of time. After stirring, pour it into a polytetrafluoroethylene mold and then dry it. Place it in water for later use.

[0009] In step (1) (a), the volume ratio of ethanol to concentrated sulfuric acid is 1~10:1~5. In step (1) (b), the molar ratio of ethyl 2,5-dihydroxyterephthalate to potassium carbonate is 1~5:1~8. The volume ratio of anhydrous ethanol to hydrazine hydrate is 1~6:1~3. In step (1) (c), 1,4-bis(4-diethoxyphosphorylbutoxy)-2,5-dihydroxybenzene-3,6-dicarboxylhydrazine and mesitylene formaldehyde are in equimolar ratio.

[0010] In step (1) (a), the reaction temperature is 75-90℃ and the reaction time is 15-20 h. After the reaction, the reacted substance is filtered, washed, and dried. In step (1) (b), the first reaction temperature is 90-110℃ and the reaction time is 2-3 hours. The second reaction temperature is 90-110℃ and the reaction time is 24-64 h. After the reaction, the substance is cooled, extracted, concentrated, and purified. The third reaction temperature is 90-110℃ and the reaction time is 24-64 h. In step (1) (c), the first drying temperature is 100-150℃ and the drying time is 50-80 h. The second drying temperature is 100-150℃ and the drying time is 12-48 h.

[0011] In some preferred embodiments, in step (1) (a), ethanol is measured and added to a 250 mL round-bottom flask, and then 2,5-dihydroxyterephthalic acid is weighed and added to the round-bottom flask while shaking to disperse / dissolve the organic compound 2,5-dihydroxyterephthalic acid. If the organic powder 2,5-dihydroxyterephthalic acid is difficult to dissolve, it can be magnetically stirred at room temperature to dissolve it or form a suspension (no strong dissolution is required). Then, the flask is placed in an ice-water bath (0~5 ℃) to cool it, and concentrated sulfuric acid is added. The concentrated sulfuric acid is added drop by drop using a constant pressure dropping funnel or a dropper while continuously stirring vigorously. After each 1~2 drops of concentrated sulfuric acid are added, pause for a few seconds until the system temperature stabilizes before continuing. This is to prevent the large amount of heat released by the mixture of concentrated sulfuric acid and ethanol from causing a sudden rise in system temperature, which could lead to the oxidation of the hydroxyl groups of 2,5-dihydroxyterephthalic acid by concentrated sulfuric acid, carbonization of the benzene ring, or violent boiling of the liquid. After feeding, the mixture was heated under reflux at 80 °C for 18 h. After the reflux was completed, it was cooled to room temperature, and 200 mL of deionized water was added to the round-bottom flask. The mixture was shaken and oscillated, filtered, washed with deionized water, and dried at 120 °C to obtain ethyl 2,5-dihydroxyterephthalate.

[0012] In step (1) (b), g of ethyl 2,5-dihydroxyterephthalate and potassium carbonate were weighed, and anhydrous acetonitrile was measured. The weighed and measured substances were added to a round-bottom flask. First, nitrogen gas was purged to purge the air from the reaction system, and then the mixture was refluxed at 100 °C for 2 h under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature. Then, diethyl phosphate (3-bromopropyl) 4-acetylmethylene ether was accurately weighed and added to the cooled round-bottom flask. Nitrogen gas was purged to purge the air from the reaction system, and then the mixture was refluxed at 100 °C for 48 h under nitrogen protection. After cooling to room temperature, the reactants were removed, and dichloromethane and deionized water were added for extraction. The organic phase was separated and concentrated under reduced pressure (the organic phase contained some water, which could be removed with anhydrous magnesium sulfate). The mixture was purified by chromatography to obtain a yellow oil. A yellow oil, anhydrous ethanol, and hydrazine hydrate were measured into a round-bottom flask. Oxygen in the reaction system was removed by nitrogen exchange, and then the mixture was refluxed at 100 °C for 48 h under nitrogen protection to obtain 1,4-bis(4-diethoxyphosphorylbutoxy)-2,5-dihydroxybenzene-3,6-dicarboxyhydrazide.

[0013] In step (1) (c), 1,4-bis(4-diethoxyphosphorylbutoxy)-2,5-dihydroxybenzene-3,6-dicarboxyhydrazide, mesitylene, and mesitylene were weighed and added to ampoules. To ensure complete dissolution, the ampoules were sonicated for approximately 15 minutes. The treated ampoules were then placed in a 120 °C oven and baked for 72 h. The product was then purified in THF using the Soxhlet extraction method for 24 h, followed by vacuum drying at 120 °C for 24 h.

[0014] In step (2), the ratio of the amount of PEEK powder (g) to the amount of concentrated sulfuric acid (mL) is 1~4:1~50.

[0015] In step (2), the reaction temperature is 30~70 ℃, the stirring reaction time is 2~6 h, and after the reaction is completed, it is stirred in ice water at a stirring speed of 400 r / min for 2~20 h. The drying temperature is 70~90 ℃, and the drying time is 24~72 h.

[0016] In step (3), the COF-PE material accounts for 10%-50% of the SPEEK solution.

[0017] In step (3), the stirring temperature is 20~30 ℃, the stirring speed is 400 r / min, and the stirring time is 12~48 h. The drying temperature is 80~120 ℃, and the drying time is 12~24 h.

[0018] Another technical solution of the present invention is the application of the SPEEK / COF-PE proton exchange membrane material prepared by the above-described method in fuel cells.

[0019] The preparation method of the SPEEK / COF-PE composite proton exchange membrane material and its application in improving proton conduction performance to realize fuel cell membranes.

[0020] In some implementation schemes, proton conduction performance is tested as follows: The obtained sample was dried at a temperature of 60~120 ℃, and the film was cut into circles with a fixed radius R=0.2 mm and a thickness of 0.50~3.50 mm.

[0021] The sample was fixed with 5-50 μm gold wire and coated with conductive silver paste on both sides. It was then dried at 30-70 °C for 10-50 min. The sample was then stabilized in an environment with 40-98% humidity and 30-90 °C. The internal resistance of the sample under different humidity and temperature conditions was then measured and fitted using an EIS impedance analyzer, and the conductivity and activation energy were calculated.

[0022] The obtained samples were placed in a closed environment, and the humidity was set to 90-98% through a program. The temperature was first increased from 30 ℃ to 90 ℃, and then decreased from 90 ℃ to 30 ℃. After several consecutive heating and cooling cycles, the operation was repeated to analyze the cyclic stability of conductivity.

[0023] The technical solution of the present invention has the following beneficial effects: 1. A balance between high proton conductivity and low swelling rate was achieved. By constructing multi-level proton conduction channels and hydrogen bond networks, the proton conduction performance of the material was significantly improved, while the excessive swelling of pure SPEEK film was suppressed, thus solving the problem of discontinuous conduction channels in traditional non-fluorine films.

[0024] 2. It improves the mechanical strength and chemical stability of the membrane material. With the structural reinforcement of COF-PE, it avoids the defects of insufficient mechanical properties and easy aging and degradation of single SPEEK membranes, thus extending the service life of proton exchange membranes.

[0025] 3. It avoids the environmental hazards and high costs of fluorine-based membranes by adopting a fluorine-free composite system, which reduces the pollution to the environment from material preparation and waste disposal. In addition, the raw materials are readily available and the process is simple, which promotes the low-cost industrialization of proton exchange membranes.

[0026] 4. It ensures the performance stability of the material within a wide temperature and humidity range, adapting to the application needs of hydrogen fuel cells in various scenarios such as new energy transportation and distributed power generation, and providing core material support for the technological upgrade in the new energy field. Attached Figure Description

[0027] Figure 1 The synthesis route diagram (A) and COF-PE structure diagram (B) of the SPEEK / COF-PE material of this invention are shown.

[0028] Figure 2 The 1H NMR spectrum of the monomer 1,4-diethyl phthalate-2,5-bis(3-(diethoxyphosphoryl)propoxy) is shown.

[0029] Figure 3 The NMR spectrum of the monomer 1,4-bis(4-diethoxyphosphorylbutoxy)-2,5-dihydroxybenzene-3,6-dicarboxyhydrazide is 1H NMR.

[0030] Figure 4 The carbon NMR spectrum of the monomer diethyl[3-({5-[(diethylphosphono)ethoxy]-2,4-dioxo-3-(hydrazonephenyl)cyclohexyl-1,5-dienyl}amino)-3-oxopropyl]phosphonate.

[0031] Figure 5 This is a comparison of the X-ray diffraction patterns of COF-PE materials.

[0032] Figure 6 This is a comparison of the infrared spectra of COF-PE materials.

[0033] Figure 7 Comparison of X-ray diffraction patterns showing the structural changes of COF-PE materials after treatment with different solvents.

[0034] Figure 8 PXRD comparison diagrams of the crystal structure stability of COF-PE materials under different pH conditions.

[0035] Figure 9 Electrochemical impedance spectroscopy (EIS) spectra of SPEEK / COF-PE material at different temperatures.

[0036] Figure 10 Electrochemical impedance spectroscopy (EIS) spectra of SPEEK / COF-PE materials under different relative humidity conditions.

[0037] Figure 11 This is a picture of a SPEEK / COF-PE material. Detailed Implementation

[0038] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0039] Example 1 (1) Synthesis of phosphorylhydrazine-containing monomers and COF-PE ① 2,5-Dihydroxyterephthalate (2.54 g) and potassium carbonate (5.52 g) were placed in anhydrous acetonitrile (40 mL) and refluxed at 100 °C for 2 h under nitrogen protection. After cooling, diethyl phosphate (3-bromopropyl)-4-acetylmethylene ether (5.41 g) was added, and reflux was continued for 48 h under the same conditions. The reaction solution was extracted with dichloromethane, dried over anhydrous magnesium sulfate, and purified by column chromatography to obtain a yellow oily intermediate, 1,4-diethyl phthalate-2,5-bis(3-(diethoxyphosphoryl)propoxy) (structure obtained by [method name missing]). 1 HNMR Figure 2 Confirmed).

[0040] ② Take the above product (5 mL), anhydrous ethanol (20 mL), and hydrazine hydrate (10 mL), and reflux at 100 °C for 48 h under nitrogen protection to obtain the target monomer 1,4-bis(4-diethoxyphosphorylbutoxy)-2,5-dihydroxybenzene-3,6-dicarboxyhydrazide (structure obtained by...). 1 H NMR Figure 3 Confirmed).

[0041] ③ The obtained monomer (1.4 g) and mesitylenealdehyde (0.336 g) were dissolved in mesitylene (1 mL), dissolved by sonication, and then sealed in a tube. The reaction was carried out at 120 °C for 72 h. The crude product was purified by Soxhlet extraction (THF) for 24 h and then vacuum dried to obtain COF-PE material. Figure 1 B). Its structure is achieved through... 13 C NMR ( Figure 4 XRD Figure 5 , and simulated spectrum Figure 1 (to) and FT-IR ( Figure 6 This is confirmed by the characteristic peaks of C=N and P=O.

[0042] (2) Preparation of SPEEK 20 g of polyether ether ketone (PEEK) powder was slowly added to 250 mL of concentrated sulfuric acid and mechanically stirred at 50 °C for 4 h. After the reaction solution cooled, it was added dropwise to ice water to precipitate the product, and stirring was continued for 12 h. The resulting sulfonated polyether ether ketone (SPEEK) was repeatedly washed until neutral and dried at 80 °C for 48 h for later use.

[0043] Example 1-1 (1) Synthesis of phosphorylhydrazine-containing monomers and COF-PE ① 2,5-Dihydroxyterephthalate (2.80 g, +10%) and potassium carbonate (6.07 g, +10%) were placed in anhydrous acetonitrile (45 mL) and refluxed at 100 °C for 2.5 h under nitrogen protection. After cooling, diethyl phosphate (3-bromopropyl) 4-acetylmethylene ether (5.95 g, +10%) was added, and the mixture was heated to 110 °C and refluxed for 36 h (the reaction time was shortened and the temperature was slightly increased). The reaction solution was extracted with dichloromethane, dried over anhydrous magnesium sulfate, and purified by rapid column chromatography to obtain a yellow oily intermediate, 1,4-diethyl phthalate-2,5-bis(3-(diethoxyphosphoryl)propoxy) (yield approximately 75%).

[0044] Steps ② and ③ are the same as in Example 1. The crude product is purified by Soxhlet extraction for 24 h and then vacuum dried at 100 °C for 24 h to obtain COF-PE material. Powder XRD characterization shows that its diffraction peak positions are consistent with those in Example 1, but the crystallinity is basically the same as in Example 1.

[0045] Examples 1-2 (1) Synthesis of phosphorylhydrazine-containing monomers and COF-PE Steps ① and ② are the same as in Implementation Case 1. ③ The obtained monomer (1.4 g) and mesitylenealdehyde (0.336 g) were dissolved in mesitylene (1 mL), dissolved by sonication, and then sealed in a tube. The reaction was carried out at 120 °C for 168 h (the reaction time was extended). The crude product was purified by Soxhlet extraction (THF) for 24 h and then vacuum dried to obtain COF-PE material. Powder XRD characterization showed that its diffraction peak positions were consistent with those in Example 1, and its crystallinity was slightly improved compared to Example 1.

[0046] Examples 1-3 The synthesis method of phosphoryl hydrazine monomer and COF-PE is the same as that in Example 1 (1).

[0047] (2) Polyetheretherketone (PEEK) powder (20 g) was slowly added to concentrated sulfuric acid (250 mL), controlling the addition rate to prevent agglomeration. The mixture was mechanically stirred at 30 °C (50 °C in the original example) for 6 h (4 h in the original example). After cooling, the reaction solution was added dropwise to ice water to precipitate the product, and stirring was continued for 12 h. The resulting sulfonated polyetheretherketone (SPEEK) was repeatedly washed until neutral and dried at 80 °C for 48 h for later use. The degree of sulfonation of the SPEEK obtained in this example was determined by titration to be approximately 58%, slightly higher than that in Example 1 (where the degree of sulfonation was approximately 53%).

[0048] The implementation of Examples 1-3, compared with Example 1, shows that a higher degree of sulfonation can also be obtained by extending the reaction time at a lower temperature.

[0049] Example 2 Chemical stability analysis and methods of COF-PE materials: Activated COF-PE samples were placed in different organic solvents (n-pentane, acetonitrile, 1,2-dichlorobenzene, methanol, 1,4-dioxane, acetone, etc.). N,N Immersed in dimethylformamide for 3 days, XRD pattern after treatment ( Figure 7 The results showed that the characteristic peak positions of each sample were basically consistent with the simulated spectrum, indicating that the crystal structure of the material remained intact in common organic solvents. Acid and alkali tolerance test ( Figure 8 This indicates that after being treated with a strong acid (HCl) at pH=1 for 3 days, the sample... θ The characteristic peak at approximately 3.5° remained unchanged, with a sharp peak shape and about 80% intensity retention, indicating a stable skeletal structure. After 3 days of immersion in a strong alkali (NaOH) at pH=14, the intensity of the same characteristic peak decreased by about 60%, significantly reducing the crystal order. These results demonstrate that the COF-PE material exhibits good resistance to strong acid environments, but its structure is easily damaged in strong alkaline environments. This case study effectively assesses the chemical and acid / alkaline stability of the material.

[0050] Example 3 Preparation of SPEEK / COF-PE: The preparation methods and steps of COF-PE and SPEEK are the same as in Example 1. 1 g of sulfonated polyether ether ketone (SPEEK) was accurately weighed using an electronic balance and dissolved in 5 mL of dimethyl sulfoxide solution. Then, 0.5 g of COF-PE material was weighed and added to the solution, and the mixture was stirred for 24 h. The mixture was then poured into a polytetrafluoroethylene mold and dried in a vacuum drying oven at 60 ℃ to form a film. The film was then removed and placed in water for later use. The resulting film material was SPEEK / COF-PE. Figure 11 ).

[0051] Example 3-1 The preparation methods and steps for COF-PE and SPEEK are the same as in Example 1. 1 g of sulfonated polyether ether ketone (SPEEK) was accurately weighed using an electronic balance and dissolved in 5 mL of dimethyl sulfoxide solution. The solution was magnetically stirred until completely dissolved. Then, 1.0 g of COF-PE material (0.5 g in the original example, increasing the doping ratio from 33% to 50%) was weighed and added to the above solution. Stirring was continued for 24 h to ensure thorough mixing. The mixture was slowly poured into a polytetrafluoroethylene mold, allowed to stand to remove bubbles, and then dried in a 60°C vacuum drying oven to form a film. After removal, the film was stored in deionized water for later use, yielding a high-doped SPEEK / COF-PE composite film with the same appearance as in Example 3.

[0052] Example 4 Proton conduction performance evaluation and methods: The SPEEK / COF-PE sample prepared in Example 3 was vacuum dried at 60°C for 12 h. After grinding, it was pressed into a pellet (250 kg / cm²), its dimensions were measured, it was fixed with gold wire, and coated with conductive silver paste. The proton conduction performance of the sample was tested under isothermal and humidity conditions using an EIS impedance analyzer. Before testing, the sample was stabilized in the set temperature and humidity environment for 24 h. First, under 90% RH constant humidity, a gradient heating and cooling cycle from 40°C to 90°C was performed (40→90°C, step size 10°C), the internal resistance was fitted, and the conductivity and activation energy were calculated. Subsequently, at a constant temperature of 40°C, the impedance change under different humidity conditions was measured. At 90% RH, the material impedance was negatively correlated with temperature: when the temperature was raised to 90°C, the real part (Z') and imaginary part (Z'') of the impedance decreased significantly, indicating that thermal activation promoted ion transport. At a constant temperature of 40°C, the impedance decreases nonlinearly with increasing humidity, and the critical range for performance improvement is when the relative humidity is ≥60%.

[0053] Through the implementation of this case, the SPEEK / COF-PE material can be evaluated as a temperature and humidity-responsive proton-conducting membrane. Its conductivity increases with both temperature and humidity, achieving highly efficient proton transport, particularly in high-humidity environments (≥90% RH), and exhibiting good cycling stability. This demonstrates that the introduction of COF materials (especially COF-PE containing hydrophilic groups) successfully optimized the microstructure of SPEEK, constructing a more efficient proton transport channel.

[0054] The above description is merely a preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in this embodiment. Therefore, any equivalent or modified versions made without departing from the spirit of the present invention fall within the scope of protection of the present invention.

Claims

1. A method for preparing a SPEEK / COF-PE composite proton exchange membrane material, characterized in that, Includes the following steps: (1) Preparation of phosphoryl-containing covalent organic framework material COF-PE: (a) 2,5-Dihydroxyterephthalic acid was esterified with ethanol under concentrated sulfuric acid catalysis to obtain ethyl 2,5-dihydroxyterephthalate; (b) The product obtained in step (a) was reacted with potassium carbonate and then subjected to a nucleophilic substitution reaction with diethyl phosphate (3-bromopropyl) ether. The intermediate product was then reacted with hydrazine hydrate to give 1,4-bis(4-diethoxyphosphorylbutoxy)-2,5-dihydroxybenzene-3,6-dicarboxylhydrazine. (c) The 1,4-bis(4-diethoxyphosphorylbutoxy)-2,5-dihydroxybenzene-3,6-dicarboxylhydrazine obtained in step (b) was subjected to a Schiff base condensation reaction with mestribenzaldehyde in an organic solvent to obtain COF-PE. (2) Preparation of sulfonated polyether ether ketone (SPEEK) via sulfonation reaction: Polyetheretherketone powder was added to concentrated sulfuric acid and stirred to react. After the reaction was completed, the polymer was added dropwise to ice water and stirred. After rinsing until neutral, it was dried. (3) Dissolve the SPEEK obtained in step (2) in a solvent, add the COF-PE obtained in step (1), mix evenly to form a film, and dry to obtain a SPEEK / COF-PE composite proton exchange membrane.

2. The method for preparing a SPEEK / COF-PE composite proton exchange membrane material according to claim 1, characterized in that, In step (a), the volume ratio of ethanol to concentrated sulfuric acid is 1~10:1~5; In step (b), the molar ratio of ethyl 2,5-dihydroxyterephthalate to potassium carbonate is 1~5:1~8; The molar ratio of 1,4-bis(4-diethoxyphosphorylbutoxy)-2,5-dihydroxybenzene-3,6-dicarboxyhydrazide to mestribenzaldehyde in step (c) is 1:

1.

3. The method for preparing a SPEEK / COF-PE composite proton exchange membrane material according to claim 2, characterized in that, In step (a), the reaction temperature is 75~100℃ and the reaction time is 15~30 h; after the reaction is completed, the reactants are filtered, washed and dried. In step (b), the product obtained in step (a) is reacted with potassium carbonate at a reaction temperature of 90-120 °C for 2-3 hours, and then reacted with diethyl phosphate (3-bromopropyl) ether at a reaction temperature of 90-120 °C for 24-64 hours for nucleophilic substitution. After the reaction is completed, the product is cooled, extracted, concentrated, and purified. The intermediate product is reacted with hydrazine hydrate at a reaction temperature of 90-120 °C for 24-64 hours to obtain 1,4-bis(4-diethoxyphosphorylbutoxy)-2,5-dihydroxyphenyl-3,6-dicarboxyhydrazide. The condensation reaction described in step (c) is a solvothermal reaction at a temperature of 100-150°C for 50-80 h. The reaction product is purified by Soxhlet extraction and dried to obtain COF-PE.

4. The method for preparing a SPEEK / COF-PE composite proton exchange membrane material according to claim 1, characterized in that, The sulfonation reaction described in step (2) involves adding polyether ether ketone (PEEK) powder to concentrated sulfuric acid and stirring the mixture at 30-70°C for 2-6 hours. After the reaction is complete, the reaction solution is precipitated in ice water, washed until neutral, and dried to obtain SPEEK. The ratio of PEEK powder (g) to concentrated sulfuric acid (mL) is 1~4:1~50.

5. The method for preparing a SPEEK / COF-PE composite proton exchange membrane material according to claim 1, characterized in that, In step (3), the COF-PE material accounts for 10%-50% of the SPEEK solution; the reaction temperature is 20~30 ℃, the reaction time is 12~48 h; the drying temperature is 80~120 ℃, and the drying time is 12~24 h.

6. The SPEEK / COF-PE composite proton exchange membrane material prepared by the preparation method according to any one of claims 1-5, characterized in that, The X-ray powder diffraction pattern of the COF-PE has a characteristic diffraction peak at 2θ=3.5±0.2°, and its infrared spectrum has characteristic absorption peaks of C=N bonds and P=O bonds.

7. The application of the SPEEK / COF-PE composite proton exchange membrane material as described in claim 6 in a proton exchange membrane fuel cell.

8. The application according to claim 7, characterized in that, The SPEEK / COF-PE composite proton exchange membrane material is used as the electrolyte membrane of the fuel cell to conduct protons and separate fuel from oxidant.

9. The application according to claim 7, characterized in that, The SPEEK / COF-PE composite proton exchange membrane material has a proton conductivity greater than or equal to 150 mS / cm at 80°C and 90% relative humidity; and an area swelling ratio less than or equal to 20% in water at 30°C.

10. A fuel cell comprising an anode, a cathode, and a proton exchange membrane located between the anode and the cathode, characterized in that, The proton exchange membrane is the SPEEK / COF-PE composite proton exchange membrane material as described in claim 6.

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