Sulfonated porous aromatic framework doped sulfonated polybenzimidazolyl polymer electrolyte membrane and preparation method thereof
A composite membrane was prepared by blending sulfonated porous aromatic frameworks with sulfonated polybenzimidazole. By utilizing the porous structure and acid-base interaction, the high efficiency of proton conduction in the proton exchange membrane over a wide temperature range was achieved, solving the problem of uneven conductivity of membrane materials under temperature changes in the prior art.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGZHOU UNIV
- Filing Date
- 2026-01-04
- Publication Date
- 2026-05-01
AI Technical Summary
Existing proton exchange membranes exhibit uneven proton conductivity at low and high temperatures, leading to unstable fuel cell performance across different temperature ranges. In particular, severe phosphoric acid loss occurs at high temperatures, failing to meet the application requirements for a wide temperature range.
A composite membrane was prepared by copolymerization of a sulfonated porous aromatic framework and sulfonated polybenzimidazole. The membrane maintained the stability of proton conductivity over a wide temperature range by utilizing the capillary effect of the porous structure and the acid-base interaction between phosphoric acid and imidazole groups.
Efficient proton conduction of proton exchange membranes was achieved in the range of room temperature to 200°C. At low temperatures, water conduction was achieved by relying on the hydrophilic groups of sulfonate groups, while at high temperatures, phosphoric acid was retained through the porous structure, thus solving the problem of conductivity balance of membrane materials under temperature changes.
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Abstract
Description
Sulfonated porous aromatic framework-doped sulfonated polybenzimidazole polymer electrolyte membrane and its preparation method Technical Field
[0001] This invention belongs to the field of polymer materials technology and relates to a proton exchange membrane applicable to a wide temperature range (from room temperature to 200°C). Specifically, it relates to a sulfonated porous aromatic framework-doped sulfonated polybenzimidazole-based polymer electrolyte membrane and its preparation method. Background Technology
[0002] Against the backdrop of the global energy structure transitioning towards cleaner and lower-carbon energy sources, proton exchange membrane fuel cells (PEMFCs), as a highly efficient and environmentally friendly energy conversion device, have attracted widespread attention from researchers. Based on operating temperature, PEMFCs can be divided into low-temperature proton exchange membrane fuel cells (operating temperature from room temperature to 100 ℃) and high-temperature proton exchange membrane fuel cells (operating temperature from 100 to 200 ℃). The proton exchange membrane (PEMs) is a crucial component of PEMFCs, and its performance directly determines the energy conversion efficiency and lifespan of the fuel cell.
[0003] Currently, the most commercially successful Nafion membrane is the perfluorosulfonic acid type, which exhibits excellent proton conductivity from room temperature to 100 °C. However, in reality, when the operating temperature approaches or even exceeds 100 °C, the evaporation of water in the Nafion membrane weakens the proton dissociation ability of the sulfonic acid groups, thereby reducing its proton conductivity. Using phosphoric acid instead of water molecules as a proton carrier at high temperatures is an effective method to improve the high-temperature proton conductivity of electrolyte membranes. For example, phosphoric acid-doped polybenzimidazole membranes (PBI) exhibit excellent proton conductivity above 100 °C. However, when the temperature is below 100 °C, on the one hand, phosphoric acid will be lost with the water generated at the electrodes or the condensate during start-up and shutdown cycles. On the other hand, the water generated during fuel cell operation cannot be discharged from the membrane in time at low temperatures, and the intermolecular forces between water molecules and phosphoric acid molecules are similar to the intermolecular forces between PBI and phosphoric acid molecules, which leads to easy loss of phosphoric acid with water.
[0004] Recent studies have found that introducing components with microporous or porous structures into a polymer matrix can generate a strong capillary effect on phosphoric acid or water molecules, locking them firmly within the pores. Theoretically, this could significantly broaden the operating temperature range of phosphoric acid-doped proton exchange membranes. However, in practice, when the temperature is below 60 °C, the membrane's conductivity is too low due to insufficient absorption of phosphoric acid, making it unsuitable for practical applications in fuel cells. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a proton exchange membrane applicable over a wide temperature range. Porous aromatic frameworks (PAFs) are a class of novel porous materials with high specific surface area, excellent chemical stability, and tunable structure. This invention prepares sulfonated porous aromatic frameworks (sPAFs) through sulfonation modification, and simultaneously prepares sulfonated polybenzimidazole (sPBIs) through copolymerization. By blending sPAFs and sPBIs in a certain proportion, a proton exchange membrane with excellent proton conductivity over a wide temperature range (room temperature to 200 °C) is prepared.
[0006] To achieve the above objectives, the chemical structural formula of the sulfonated porous aromatic framework (sPAF) provided by this invention is as follows:
[0007] ;
[0008] Where m represents the degree of polymerization, and m is between 5000 and 100000.
[0009] The chemical structural formula of sulfonated polybenzimidazole (sPBI) is as follows:
[0010] ;
[0011] Where x ranges from 0 to 1.
[0012] The proton exchange membrane of this invention, when immersed in water at low temperatures (room temperature to 100 °C), provides free protons through the dissociation of high-density sulfonic acid groups on the polymer and porous material. These protons then combine with water molecules to form hydrated protons, ensuring its proton conductivity at low temperatures. When the temperature approaches 100 °C, the micropores in the spAF (suppressed phosphoric acid) create a capillary effect with water molecules, preventing a decrease in conductivity due to rapid water evaporation caused by temperature increases. At high temperatures (100–200 °C), when phosphoric acid is immersed in the membrane, the imidazole groups on the PBI (phosphoric acid compound) can form an acid-base reaction with phosphoric acid molecules, promoting phosphoric acid absorption. Simultaneously, the capillary effect between the micropores on the spAF and phosphoric acid molecules inhibits phosphoric acid loss, ensuring its proton conductivity at high temperatures.
[0013] The preparation process of this composite membrane is as follows:
[0014] (1) Preparation of PAF
[0015] Under nitrogen atmosphere, tetra(4-bromophenyl)methane, 4,4'-biphenyl diboronic acid, and potassium carbonate (K₂CO₃) solution were added to N,N-dimethylformamide (DMF). After thorough mixing, tetra(triphenylphosphine)palladium was added. The reaction was carried out at 150 °C for 24 hours. The crude product was thoroughly washed with chloroform, tetrahydrofuran, and distilled water by centrifugation to remove K₂CO₃, unreacted monomers, and oligomers. Finally, the PAF was dried in a vacuum oven at 80 °C for 24 hours before use.
[0016] The molar ratio of tetra(4-bromophenyl)methane to 4,4'-biphenyl diboronic acid is 1:2; the concentration of potassium carbonate solution is 2M, and the molar ratio of potassium carbonate to 4,4'-biphenyl diboronic acid is 3.85:1; the molar ratio of tetra(triphenylphosphine)palladium to 4,4'-biphenyl diboronic acid is 1:20.
[0017] (2) Preparation of sPAF
[0018] Under an ice-water bath environment, the dried PAF was uniformly dispersed in dichloromethane, and chlorosulfonic acid (in excess, with a molar ratio of approximately 20:1 to PAF) was slowly added dropwise to sulfonate the PAF. After reacting for 72 hours, the PAF was thoroughly washed in deionized water until neutral. Finally, the sPAF was dried in an 80 °C vacuum oven for 24 hours before use.
[0019] (3) Preparation of sPBI
[0020] 3,3',4,4'-Biphenyltetramine, monosodium 2-sulfonic terephthalate, and terephthalic acid were dissolved in polyphosphoric acid (PPA) to prepare a 10% polymer mass fraction solution. Polymerization was carried out under nitrogen protection with a gradient temperature increase from 100 to 180 °C and mechanical stirring until the reactants exhibited a noticeable "spindle climbing" phenomenon, at which point the reaction was stopped. The product was washed with deionized water and ethanol until neutral. Finally, sPBI was dried in a vacuum oven at 60 °C for 24 hours. By adjusting the ratio of monosodium 2-sulfonic terephthalate to terephthalic acid, PBI polymers with different degrees of sulfonation could be obtained, named sPBI-x (where x represents the proportion of monosodium 2-sulfonic terephthalate to all dicarboxylic acid monomers, i.e., the degree of sulfonation).
[0021] The molar ratio of 3,3',4,4'-biphenyltetramine to dicarboxylic acid monomers (terephthalic acid and 2-sulfonic terephthalic acid monosodium salt) is 1.1:1, the molar ratio of 2-sulfonic terephthalic acid monosodium salt to terephthalic acid is 3:7-7:3, the gradient temperature is 100℃ for 1 h followed by 140℃, 140℃ for 1 h followed by 180℃, and the heating rate is 40℃ / h.
[0022] (4) Preparation of composite membranes with wide temperature range
[0023] sPAF was dispersed in dimethyl sulfoxide (DMSO). After sPBI was fully dissolved in DMSO, the two were mixed and stirred until homogeneous. The mixture was then poured onto a clean glass plate and dried in a 60 °C oven to prepare a uniform and transparent composite membrane. The composite membrane was immersed in 2M sulfuric acid at 60 °C for two hours to remove inorganic salts, and then washed with deionized water until neutral. This membrane can be used directly at low temperatures. For high-temperature use, the composite membrane needs to be immersed in 85 wt% phosphoric acid at 80 °C for 24 hours to obtain a phosphoric acid-doped polymer electrolyte membrane. The resulting membrane was named sPAF-y / sPBI-x (y represents the mass ratio of sPAF to the polymer membrane; x represents the degree of sulfonation of PBI).
[0024] Of these, the mass of sPAF accounts for 2%-10% of the total mass of sPAF and sPBI.
[0025] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:
[0026] This invention mixes a sulfonated porous aromatic framework polymer (PBI) with a sulfonated polybenzimidazole (PBI). Through the synergistic effect of the two materials, the membrane material can absorb water and efficiently conduct protons at low temperatures by relying on the hydrophilic groups of the sulfonate groups. In high-temperature environments, the "siphoning effect" of the porous structure and the retention of phosphate by the imidazole groups on the PBI solve the current balance effect between conductivity and temperature in proton exchange membrane materials, enabling the membrane to maintain good proton conductivity over a wide temperature range. Attached Figure Description
[0027] Figure 1 shows the infrared spectra of PAF and sPAF.
[0028] Figure 2 shows the structural formula and NMR spectrum of sulfonated PBI. Detailed Implementation
[0029] The present invention will be further described below with reference to embodiments.
[0030] Example 1
[0031] The preparation method of a wide-temperature proton exchange membrane based on sulfonated porous aromatic framework / sulfonated polybenzimidazole includes the following steps:
[0032] (1) Preparation of PAF
[0033] Under nitrogen atmosphere, 0.5 g (0.79 mmol) of (4-bromophenyl)methane, 0.38 g (1.56 mmol) of 4,4'-biphenyl diboronic acid (molar ratio 1:2), and 3 ml of 2M potassium carbonate (K₂CO₃) aqueous solution were added to 24 ml of N,N-dimethylformamide (DMF). After thorough mixing, 0.09 g of tetrakis(triphenylphosphine)palladium was added. The reaction was carried out at 150 °C for 24 hours. The crude product was thoroughly washed with chloroform, tetrahydrofuran, and distilled water by centrifugation to remove K₂CO₃, unreacted monomers, and oligomers. Finally, the PAF was dried in a vacuum oven at 80 °C for 24 hours before use. Its structural formula is:
[0034]
[0035] (2) Preparation of sPAF
[0036] Under an ice-water bath environment, 0.1 g of dried PAF was uniformly dispersed in 10 ml of dichloromethane. 1 ml of chlorosulfonic acid was slowly added dropwise (at a rate of 20 drops / min) to sulfonate the PAF. After reacting for 72 hours, the mixture was thoroughly washed in deionized water until neutral. Finally, the sPAF was dried in an 80 °C vacuum oven for 24 hours before use. Its structural formula is:
[0037]
[0038] (3) Preparation of sPBI-0.3
[0039] A clean 500ml three-necked flask was used. Under a nitrogen atmosphere at 110℃, 213.50g of polyphosphoric acid (PPA) was added and stirred until no bubbles appeared. After thorough mixing, 4.63g of 3,3'-diaminobenzidine was added and stirred for 30 minutes. After thorough mixing, 1.74g of monosodium terephthalate sulfonate was added and stirring continued for 30 minutes. Finally, 2.52g of terephthalic acid was added. Under nitrogen protection, the temperature was gradually increased from 100℃ to 180℃ (reacting at 100℃ for 1 hour, then increased to 140℃, then at 140℃ for 1 hour, then increased to 180℃, with a heating rate of 40℃ / h). The reaction was stopped when a clear "climbing rod" phenomenon was observed. The product was poured into deionized water to form a fibrous polymer, and then immersed in a potassium carbonate aqueous solution to neutralize the PPA. Finally, the product was washed with deionized water and ethanol until neutral. Its structural formula is:
[0040]
[0041] (4) Preparation of sPAF / sPBI composite membrane
[0042] 0.01 g of sPAF was dispersed in 2 ml of dimethyl sulfoxide (DMSO). After 0.49 g of sPBI-0.3 was fully dissolved in 8 ml of DMSO, the two were mixed and stirred thoroughly. The mixture was then poured onto a clean glass plate and dried in a 60°C oven to prepare a uniform and transparent composite membrane sPAF-0.02 / sPBI-0.3. The composite membrane was then immersed in 2M sulfuric acid at 60°C for two hours to remove inorganic salts, and then washed with deionized water until neutral. This membrane can be used directly at low temperatures. For high-temperature use, sPAF-0.02 / sPBI-0.3 was immersed in 85% phosphoric acid for 24 hours to obtain a phosphoric acid-doped polymer electrolyte membrane.
[0043] The measured performance parameters of sPAF-0.02 / sPBI-0.3 are as follows: water absorption rate of 17.79% and electrical conductivity of 21.59 mS / cm at room temperature. −1 At 80 ℃, the water absorption rate is 21.55%, and the electrical conductivity is 40.19 mS / cm. −1 After soaking in phosphoric acid, the phosphoric acid absorption rate was 115.31%, and the conductivity at 180 °C was 79.93 mS / cm. −1 How long did it take for the phosphate-doped membrane to retain 68.35% of the phosphate after immersing it in water? The membrane was then immersed in Fenton's reagent (4 ppm Fe). 2+ In 3% H2O2, after being placed at 80 °C for 120 hours, its remaining weight was measured again and found to be 85.63%, proving that it has good stability.
[0044] Example 2
[0045] The method for preparing a wide-temperature proton exchange membrane based on a sulfonated porous aromatic framework / sulfonated polybenzimidazole provided in this embodiment is basically the same as that in Example 1, except that 0.5sPBI is prepared in step (3). The molar ratio of 2-sulfonic acid terephthalic acid monosodium salt to terephthalic acid is 1:1.
[0046] The structural formula of 0.5sPBI is:
[0047]
[0048] The measured performance parameters of sPAF-0.02 / sPBI-0.5 are as follows: water absorption rate of 21.85% and electrical conductivity of 26.37 mS / cm at room temperature. −1 At 80 ℃, the water absorption rate is 26.78%, and the electrical conductivity is 51.08 mS / cm. −1After soaking in phosphoric acid, the phosphoric acid absorption rate was 130.25%, and the conductivity at 180 °C was 93.87 mS / cm. −1 How long did it take for the phosphate-doped membrane to retain 73.51% of the phosphate after immersing it in water? The membrane was then immersed in Fenton's reagent (4 ppm Fe). 2+ In 3% H2O2, after being placed at 80 °C for 120 hours, its remaining weight was measured again and found to be 86.21%, proving that it has good stability.
[0049] Example 3
[0050] The method for preparing a wide-temperature proton exchange membrane based on a sulfonated porous aromatic framework / sulfonated polybenzimidazole provided in this embodiment is basically the same as that in Example 1, except that 0.7sPBI is prepared in step (3). The molar ratio of 2-sulfonic acid terephthalic acid monosodium salt to terephthalic acid is 7:3.
[0051] The structural formula of 0.7sPBI is:
[0052]
[0053] The measured performance parameters of sPAF-0.02 / sPBI-0.7 are as follows: water absorption rate of 25.01% and electrical conductivity of 31.22 mS / cm at room temperature. −1 At 80 ℃, the water absorption rate is 32.35%, and the electrical conductivity is 60.31 mS / cm. −1 After soaking in phosphoric acid, the phosphoric acid absorption rate was 151.49%, and the conductivity at 180 °C was 113.25 mS / cm. −1 How long should the phosphate-doped membrane be soaked in water to achieve a phosphate retention rate of 76.65%? The membrane was then immersed in Fenton's reagent (4 ppm Fe). 2+ In 3% H2O2, after being placed at 80 °C for 120 hours, its remaining weight was measured again and found to be 86.99%, proving that it has good stability.
[0054] Example 4
[0055] The preparation method of the wide-temperature proton exchange membrane based on sulfonated porous aromatic framework / sulfonated polybenzimidazole provided in this embodiment is basically the same as that in Example 3, except that the proportion of sPAF in step (4) is 4%.
[0056] The measured performance parameters of sPAF-0.04 / sPBI-0.7 are as follows: water absorption rate of 28.31% and electrical conductivity of 34.96 mS / cm at room temperature. −1 At 80 ℃, the water absorption rate is 35.87%, and the electrical conductivity is 63.33 mS / cm. −1After soaking in phosphoric acid, the phosphoric acid absorption rate was 158.32%, and the conductivity at 180 °C was 119.56 mS / cm. −1 How long did it take for the phosphate-doped membrane to retain 79.33% of the phosphate after immersion in water? The membrane was then immersed in Fenton's reagent (4 ppm Fe). 2+ In 3% H2O2, after being placed at 80 °C for 120 hours, its remaining weight was measured again and found to be 88.31%, proving that it has good stability.
[0057] Example 5
[0058] The preparation method of the wide-temperature proton exchange membrane based on sulfonated porous aromatic framework / sulfonated polybenzimidazole provided in this embodiment is basically the same as that in Example 3, except that the proportion of sPAF in step (4) is 6%.
[0059] The measured performance parameters of sPAF-0.06 / sPBI-0.7 are as follows: water absorption rate of 31.67% and electrical conductivity of 37.47 mS / cm at room temperature. −1 At 80 ℃, the water absorption rate is 38.09%, and the electrical conductivity is 65.61 mS / cm. −1 After soaking in phosphoric acid, the phosphoric acid absorption rate was 164.52%, and the conductivity at 180 °C was 127.34 mS / cm. −1 How long did it take for the phosphate-doped membrane to retain 83.28% of the phosphate after immersing it in water? The membrane was then immersed in Fenton's reagent (4 ppm Fe). 2+ In 3% H2O2, after being placed at 80 °C for 120 hours, its remaining weight was measured again and found to be 89.47%, proving that it has good stability.
[0060] Example 6
[0061] The preparation method of the wide-temperature proton exchange membrane based on sulfonated porous aromatic framework / sulfonated polybenzimidazole provided in this embodiment is basically the same as that in Example 3, except that the proportion of sPAF in step (4) is 8%.
[0062] The measured performance parameters of sPAF-0.08 / sPBI-0.7 are as follows: water absorption rate of 33.29% and electrical conductivity of 40.62 mS / cm at room temperature. −1 At 80 ℃, the water absorption rate is 40.28%, and the electrical conductivity is 68.27 mS / cm. −1 After soaking in phosphoric acid, the phosphoric acid absorption rate was 171.42%, and the conductivity at 180 °C was 125.54 mS / cm. −1 How long should the phosphate-doped membrane be soaked in water to achieve a phosphate retention rate of 86.28%? The membrane was then immersed in Fenton's reagent (4 ppm Fe). 2+In 3% H2O2, after being placed at 80 °C for 120 hours, its remaining weight was measured again and found to be 90.28%, proving that it has good stability.
[0063] Example 7
[0064] The preparation method of the wide-temperature proton exchange membrane based on sulfonated porous aromatic framework / sulfonated polybenzimidazole provided in this embodiment is basically the same as that in Example 3, except that the proportion of sPAF in step (4) is 10%.
[0065] The measured performance parameters of sPAF-1.0 / sPBI-0.7 are as follows: water absorption rate of 34.35% and electrical conductivity of 42.35 mS / cm at room temperature. −1 At 80 ℃, the water absorption rate is 41.36%, and the electrical conductivity is 69.91 mS / cm. −1 After soaking in phosphoric acid, the phosphoric acid absorption rate was 168.20%, and the conductivity at 180℃ was 121.97 mS / cm. −1 How long should the phosphate-doped membrane be soaked in water to achieve a phosphate retention rate of 88.51%? The membrane was then immersed in Fenton's reagent (4 ppm Fe). 2+ In 3% H2O2, after being placed at 80℃ for 120 hours, its remaining weight was measured again and found to be 91.37%, proving that it has good stability.
[0066] Comparative Example 1
[0067] The method for preparing a wide-temperature proton exchange membrane based on sulfonated porous aromatic framework / sulfonated polybenzimidazole provided in this embodiment is basically the same as that in Example 1. The difference is that in this embodiment, 0.7sPBI from Example 3 is prepared into a membrane separately, without doping with sPAF prepared in step (2).
[0068] Under the same experimental conditions, the performance parameters of sPBI-0.7 were measured as follows: water absorption rate of 23.58% and electrical conductivity of 25.87 mS / cm at room temperature. −1 At 80 ℃, the water absorption rate is 29.28%, and the electrical conductivity is 58.31 mS / cm. −1 After soaking in phosphoric acid, the phosphoric acid absorption rate was 141.21%, and the conductivity at 180 °C was 110.38 mS / cm. −1 How long did it take for the phosphate-doped membrane to retain 69.78% of the phosphate after immersing it in water? The membrane was then immersed in Fenton's reagent (4 ppm Fe). 2+ In 3% H2O2, after being placed at 80 °C for 120 hours, its remaining weight was measured again and found to be 83.21%, proving that it has good stability.
Claims
1. A sulfonated porous aromatic framework-doped sulfonated polybenzimidazole-based polymer electrolyte membrane, characterized in that: The electrolyte membrane is obtained by blending sPAF and sPBI in a certain proportion; wherein, the chemical structural formula of the sulfonated porous aromatic framework sPAF is as follows: Where m represents the degree of polymerization, which is between 5000 and 100000; the chemical structural formula of sulfonated polybenzimidazole sPBI is: x ranges from 0 to 1.
2. The method for preparing a sulfonated porous aromatic framework-doped sulfonated polybenzimidazole-based polymer electrolyte membrane according to claim 1, characterized in that, The preparation method is as follows: sPAF is dispersed in dimethyl sulfoxide, sPBI is fully dissolved in DMSO, and then the two are mixed and stirred evenly. The mixed solution is then poured onto a clean glass plate and placed in a 60°C oven to dry, thus preparing a uniform and transparent composite membrane. The composite membrane is then immersed in 2M sulfuric acid at 60°C for two hours to remove inorganic salts from the membrane, and then washed with deionized water until neutral. The obtained membrane is used for low-temperature applications. The composite membrane is then immersed in 85wt% phosphoric acid at 80°C for 24 hours to obtain a phosphoric acid-doped polymer electrolyte membrane, which is used for high-temperature applications.
3. The method for preparing a sulfonated porous aromatic framework-doped sulfonated polybenzimidazole-based polymer electrolyte membrane according to claim 2, characterized in that, The preparation steps of sPAF are as follows: (1) Under nitrogen atmosphere, tetra(4-bromophenyl)methane, 4,4'-biphenyl diboronic acid and potassium carbonate solution are added to N,N-dimethylformamide. After stirring thoroughly, tetra(triphenylphosphine)palladium is added and reacted at 150 °C for 24 hours. The crude product is thoroughly washed with chloroform, tetrahydrofuran and distilled water by centrifugation to remove potassium carbonate and unreacted monomers and oligomers. Finally, the obtained PAF is placed in an 80 °C vacuum oven and dried for 24 hours for use. (2) Under ice-water bath atmosphere, the dried PAF is uniformly dispersed in dichloromethane, and chlorosulfonic acid is added dropwise to sulfonate the PAF. After reacting for 72 hours, it is poured into deionized water and thoroughly washed until neutral. Finally, the obtained sPAF is placed in an 80 °C vacuum oven and dried for 24 hours for use.
4. The method for preparing a sulfonated porous aromatic framework-doped sulfonated polybenzimidazole-based polymer electrolyte membrane according to claim 3, characterized in that, The molar ratio of tetra(4-bromophenyl)methane to 4,4'-biphenyl diboronic acid is 1:
2.
5. The method for preparing a sulfonated porous aromatic framework-doped sulfonated polybenzimidazole-based polymer electrolyte membrane according to claim 3, characterized in that, The potassium carbonate solution concentration was 2M, and the molar ratio of potassium carbonate to 4,4'-biphenyldiboronic acid was 3.85:1; the molar ratio of tetrakis(triphenylphosphine)palladium to 4,4'-biphenyldiboronic acid was 1:
20.
6. The method for preparing a sulfonated porous aromatic framework-doped sulfonated polybenzimidazole-based polymer electrolyte membrane according to claim 3, characterized in that, The molar ratio of chlorosulfonic acid to PAF added was 20:
1.
7. The method for preparing a sulfonated porous aromatic framework-doped sulfonated polybenzimidazole-based polymer electrolyte membrane according to claim 2, characterized in that, The preparation method of sPBI is as follows: 3,3',4,4'-biphenyltetramine, 2-sulfonic terephthalic acid monosodium salt, and terephthalic acid are dissolved in polyphosphoric acid to prepare a polymer mass fraction of 10%. The temperature is gradually increased from 100 to 180 °C under nitrogen protection, and the polymerization is carried out with mechanical stirring until the reactants show obvious "spin climbing" phenomenon, at which point the reaction is stopped. The product is washed with deionized water and ethanol until neutral. Finally, sPBI is dried in a vacuum oven at 60 °C for 24 hours.
8. The method for preparing a sulfonated porous aromatic framework-doped sulfonated polybenzimidazole-based polymer electrolyte membrane according to claim 7, characterized in that, The molar ratio of 3,3',4,4'-biphenyltetramine to dicarboxylic acid monomer is 1.1:1, wherein the dicarboxylic acid monomer is terephthalic acid and 2-sulfonic acid terephthalic acid monosodium salt; the molar ratio of 2-sulfonic acid terephthalic acid monosodium salt to terephthalic acid is 3:7-7:
3.
9. The method for preparing a sulfonated porous aromatic framework-doped sulfonated polybenzimidazole-based polymer electrolyte membrane according to claim 7, characterized in that, The gradient temperature increase involves reacting at 100℃ for 1 hour, then increasing to 140℃, and then reacting at 140℃ for 1 hour, followed by increasing to 180℃, with a heating rate of 40℃ / h.
10. The method for preparing a sulfonated porous aromatic framework-doped sulfonated polybenzimidazole-based polymer electrolyte membrane according to claim 2, characterized in that, The mass of sPAF accounts for 2%-10% of the total mass of sPAF and sPBI.