Crosslinked hydrophilic-hydrophobic double comb type sulfonated polybenzimidazole proton exchange membrane for electrolysis of water and preparation method thereof
By preparing a cross-linked hydrophilic-hydrophobic dual-comb sulfonated polybenzimidazole proton exchange membrane, the problems of fluoride contamination and high cost of perfluorosulfonic acid polymer membranes were solved, the proton conductivity and mechanical properties of the membrane were improved, and the durability and stability of electrolyzed water were enhanced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGZHOU UNIV
- Filing Date
- 2026-04-10
- Publication Date
- 2026-06-02
AI Technical Summary
Among existing proton exchange membrane water electrolysis technologies, perfluorosulfonic acid polymer membranes have disadvantages such as fluoride pollution risk, high cost and high H2 permeability, sulfonated aromatic polymer membranes have poor dimensional stability, affecting device stability, and polybenzimidazole has low proton conductivity.
Crosslinked hydrophilic/hydrophobic dual-comb sulfonated polybenzimidazole proton exchange membranes were prepared by introducing alkyl side chains to form hydrophilic/hydrophobic dual-comb amphipathic membranes, and lithium-state sulfonated benzimidazole small molecule crosslinking agents were used to form hydrogen bond networks, thereby optimizing the microphase separation morphology and mechanical properties of the membrane.
It improves the proton conductivity of the membrane, inhibits swelling, enhances mechanical properties and oxidative stability, improves the durability of water electrolysis, simplifies the preparation process, and reduces costs.
Smart Images
Figure CN122127599A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer electrolyte membranes, specifically relating to a cross-linked hydrophilic and hydrophobic dual-comb sulfonated polybenzimidazole proton exchange membrane for water electrolysis and its preparation method. Background Technology
[0002] Among numerous hydrogen production technologies, proton exchange membrane (PEM) water electrolysis is considered the most promising technology for the sustainable production of green hydrogen from water and intermittent renewable energy sources. PEMs, as the core component of proton exchange membrane electrolyzers (PEMWEs), have naturally become a hot research topic. Currently, PEMs used in PEMWEs are mostly perfluorosulfonic acid polymer membranes, represented by Nafion membranes, which exhibit excellent chemical stability and high proton conductivity at room temperature. However, these membranes suffer from drawbacks such as fluoride pollution risk, high cost, and high H2 permeability. Therefore, researchers are actively developing new, cost-effective, and relatively environmentally friendly PEMs to overcome the shortcomings of perfluorosulfonic acid polymer membranes.
[0003] In recent years, sulfonated aromatic polymers have been considered as potential alternatives to perfluorosulfonic acid polymers. For example, sulfonated polyether ether ketones, due to their ether bonds, exhibit excellent film-forming properties and are widely used in the preparation of proton exchange membranes. However, these polymer membranes suffer from poor dimensional stability, affecting device stability. Polybenzimidazole, with its good dimensional stability and excellent film-forming properties, is a good material for membrane preparation; however, its low proton conductivity limits its application in the proton exchange membrane field. Summary of the Invention
[0004] This invention designs and prepares sulfonated benzimidazole small molecules (sBI) and hydrophilic / hydrophobic bicomb amphoteric polybenzimidazole (OPBI-PS-C). Using sBI as a crosslinking agent, a hydrophilic / hydrophobic bicomb type sulfonated polybenzimidazole proton exchange membrane (OPBI-PS-C / sBI-n) is prepared, which inhibits membrane swelling, improves membrane mechanical properties, and enhances water electrolysis durability. To achieve the above objectives, the crosslinked membrane preparation steps are as follows:
[0005] (1) Preparation of polybenzimidazole (OPBI)
[0006] Under a nitrogen atmosphere, 3,3'-diaminobenzidine (DAB) and 4,4'-dicarboxylic acid diphenyl ether (OBBA) were dissolved in polyphosphoric acid (PPA). The reaction was carried out at 140 °C for 3 hours, followed by 24 hours at 180 °C (the molar ratio of DAB to OBBA was 1:1). After the reaction, the mixed solution was poured into deionized water for cooling, and then washed and neutralized with deionized water and NaHCO3 (pH=7). After neutralization, the product was dried in an oven. The resulting polymer was named OPBI, with the amount of polyphosphoric acid exceeding 10 times the total mass of the monomers.
[0007] (2) Preparation of hydrophilic / hydrophobic bicomb polybenzimidazole (OPBI-PS-C)
[0008] Dissolve 1.00 g OPBI in 40 mL DMSO, add 0.2 g sodium hydride (NaH) and purge with nitrogen gas, react at 40 °C for 5 hours, then add 0.181-0.310 g 1,3-propanesulfonic acid lactone (PS) and 0.06-0.2244 g bromoalkane (bromohexane or bromoethane), and continue the reaction at 40 °C for 12 hours. Then, while stirring, pour the mixed solution into acetone, and the precipitate is the hydrophilic / hydrophobic bicomb type polybenzimidazole (OPBI-PS-C), which is then dried in an oven at 60 °C for 24 hours.
[0009] The structural formula of hydrophilic / hydrophobic bicomb polybenzimidazole (OPBI-PS-C) is shown below:
[0010]
[0011] (3) Preparation of lithium-state sulfonated benzimidazole small molecule crosslinking agent (sBI-Li)
[0012] Under a nitrogen atmosphere, at temperatures above 80 °C, residual oxygen in the polyphosphoric acid solvent was removed by mechanical stirring. Then, 3,3'-diaminobenzidine (DAB) and sodium isophthalic acid-5-sulfonate (s-IPA) were added sequentially. After complete dissolution, the temperature was first raised to 140 °C and reacted for 3 h. Then, the temperature was raised to 180 °C and the reaction continued for 15 h until the reaction solution changed color. The brown solution was then poured into a large amount of deionized water. The resulting brown powder was thoroughly washed with deionized water and then neutralized with lithium hydroxide to obtain sBI-Li.
[0013] The molar ratio of 3,3'-diaminobenzidine to sodium isophthalic acid-5-sulfonate is 1:2.1, and the amount of polyphosphoric acid used is more than 10 times the total mass of the monomers.
[0014] The structural formula of the lithium-state sulfonated benzimidazole small molecule crosslinking agent (sBI-Li) is shown below:
[0015]
[0016] (4) Preparation of OPBI-PS-C / sBI-n crosslinked membrane
[0017] A certain proportion of OPBI-PS-C and sBI-Li were weighed and dissolved in 5 mL of DMSO to form a homogeneous mixture. This mixture was then dropped onto a flat glass plate and dried in a 60°C oven for 24 h to form a membrane. The resulting membrane was then immersed in 3M sulfuric acid for 24 h and washed several times with water until a neutral pH was reached, yielding a proton-type membrane. The crosslinking reaction was carried out in a vacuum oven at 80°C for 24 h. The obtained membrane is denoted as OPBI-PS-C / sBI-n. (The total mass of OPBI-PS-C and sBI-Li is 0.2 g, and n represents the proportion of sBI-Li in the total mass; n can be 2, 4, or 6). The amount of sBI-Li crosslinking agent used was 2-6% of the total mass of sBI-Li and OPBI-PS-C.
[0018] The structural formula of the prepared proton exchange composite membrane is shown below:
[0019]
[0020] The cross-linked hydrophilic and hydrophobic dual-comb sulfonated polybenzimidazole proton exchange membrane prepared by this invention can be used for proton exchange membrane water electrolysis.
[0021] The present invention has the following advantages:
[0022] (1) The present invention introduces alkyl side chains into its main chain to form a hydrophilic / hydrophobic comb-like amphoteric membrane. The sulfonic acid chain in the membrane promotes the formation of zwitterion clusters, while the alkyl side chains enhance the stacking of hydrophobic segments. This unique structural design optimizes the microphase separation morphology of the membrane and can improve the proton conductivity of the membrane. Secondly, crosslinking is considered an effective way to inhibit membrane swelling and enhance mechanical properties, and can also alleviate the attack of oxygen free radicals on the main chain, thereby improving the durability of electrolyzed water.
[0023] (2) The addition of crosslinking agent sBI forms a hydrogen bond network, which improves the water absorption rate and optimizes the oxidative stability of the membrane.
[0024] (3) The composite membrane has a simple preparation process and good film-forming performance. Attached Figure Description
[0025] Figure 1 For OPBI-PS-C 1 HNMR image.
[0026] Figure 2 For sBI-Li 1 HNMR image. Detailed Implementation
[0027] The present invention will be further described below with reference to specific embodiments.
[0028] Example 1
[0029] (1) Under a N2 atmosphere, 1.07 g DAB and 1.29 g OBBA were dissolved in 20 g PPA. The mixture was heated to 140 °C and reacted for 3 hours, followed by a reaction at 180 °C for 24 hours. After the reaction was completed, the mixed solution was poured into deionized water for cooling, and then washed and neutralized with deionized water and NaHCO3 (pH=7). After neutralization, the product was dried in an oven, and the resulting polymer was named OPBI.
[0030] (2) Dissolve 1.00 g OPBI in 40 mL DMSO, add 0.2 g sodium hydride (NaH) and purge with nitrogen gas, react at 40 °C for 5 hours, then add 0.310 g 1,3-propanesulfonic acid lactone (PS) and 0.06 g bromohexane (C), continue to react at 40 °C for 12 hours, then pour the mixed solution into acetone while stirring, and the precipitate is the hydrophilic / hydrophobic double comb type polybenzimidazole (OPBI-PS-C), and then dry it in an oven at 60 °C for 24 hours.
[0031] (3) Under a nitrogen atmosphere, at a temperature above 80 °C, the residual oxygen in the polyphosphoric acid (20 g) used as a solvent was removed by mechanical stirring. Then, 1.07 g of DAB and 2.81 g of s-IPA were added sequentially. After complete dissolution, the temperature was first raised to 140 °C and reacted for 3 h. Then, the temperature was raised to 180 °C and the reaction was continued for 15 h until the reaction solution changed color. The brown solution was then poured into a large amount of deionized water. The resulting brown powder was thoroughly washed with deionized water and then neutralized with lithium hydroxide to obtain sBI-Li.
[0032] (4) Weigh 0.196 g of OPBI-PS-C and 0.004 g of sBI-Li and dissolve them in 5 mL of DMSO to form a homogeneous mixture. Drop the mixture onto a flat glass plate and dry it in an oven at 60 °C for 24 h to form a membrane. Then, soak the obtained membrane in 3M sulfuric acid for 24 h and wash it several times with water until a neutral pH is reached to obtain a proton-type membrane. The crosslinking reaction is carried out by heating at 80 °C in a vacuum oven for 24 h. The obtained membrane is denoted as OPBI-PS-C / sBI-2.
[0033] The performance parameters of the prepared exchange membrane are as follows: the proton conductivity of the membrane reaches 41.0 mScm at 80 °C. -1The water absorption rate was 68.1%, the swelling rate was 7%, and the remaining weight after treatment with Fenton's reagent was 87.73% (oxidative stability). The prepared PEM was used to fabricate a membrane electrode (anodine catalyst: IrO2, cathode catalyst: Pt / C). PEM electrolysis of water was tested (40 ℃, electrolyte: 0.2% H2SO4). The current density was 1350 mA cm⁻¹ at a voltage of 2V. -2 , at 0.5 A cm -2 After operating at current density for 30 hours, the voltage increased by only 1.5%.
[0034] Example 2
[0035] The preparation of OPBI-PS-C and sBI-Li is the same as in Example 1.
[0036] Weigh 0.192 g of OPBI-PS-C and 0.008 g of sBI-Li and dissolve them in 5 mL of DMSO to form a homogeneous mixture. Add the mixture dropwise onto a flat glass plate and dry it in a 60°C oven for 24 h to form a membrane. Then, soak the obtained membrane in 3M sulfuric acid for 24 h and wash it several times with water until a neutral pH is reached to obtain a proton-type membrane. The crosslinking reaction is performed by heating at 80°C in a vacuum oven for 24 h. The obtained membrane is designated OPBI-PS-C / sBI-4.
[0037] The performance parameters of the prepared exchange membrane are as follows: the proton conductivity of the membrane reaches 36.0 mScm at 80 °C. - 1. The water absorption rate was 59.3%, the swelling rate was 5.5%, and the remaining weight after treatment with Fenton's reagent was 91.17% (oxidative stability). The prepared PEM was used to fabricate a membrane electrode (anodine catalyst: IrO2, cathode catalyst: Pt / C). PEM electrolysis of water was tested (40 ℃, electrolyte: 0.2% H2SO4, current density was 1270 mA cm⁻¹ at 2V). -2 , at 0.5 A cm -2 After operating at current density for 30 hours, the voltage increased by only 1.3%.
[0038] Example 3
[0039] The preparation of OPBI-PS-C and sBI-Li is the same as in Example 1.
[0040] Weigh 0.188 g of OPBI-PS-C and 0.012 g of sBI-Li and dissolve them in 5 mL of DMSO to form a homogeneous mixture. Add the mixture dropwise onto a flat glass plate and dry it in a 60°C oven for 24 h to form a membrane. Then, soak the obtained membrane in 3M sulfuric acid for 24 h and wash it several times with water until a neutral pH is reached to obtain a proton-type membrane. The crosslinking reaction is performed by heating at 80°C in a vacuum oven for 24 h. The obtained membrane is designated OPBI-PS-C / sBI-6.
[0041] The performance parameters of the prepared exchange membrane are as follows: the proton conductivity of the membrane reaches 24.0 mScm at 80 °C. -1 The water absorption rate was 52.7%, the swelling rate was 5%, and the remaining weight after treatment with Fenton's reagent was 93.65% (oxidative stability). The prepared PEM was used to fabricate a membrane electrode (anodine catalyst: IrO2, cathode catalyst: Pt / C). PEM electrolysis of water was tested (40 ℃, electrolyte: 0.2% H2SO4). The current density was 930 mA cm⁻¹ at a voltage of 2V. -2 , at 0.5 A cm -2 After operating at current density for 30 hours, the voltage increased by only 1.0%.
[0042] Example 4
[0043] The preparation of OPBI-PS-C and sBI-Li is the same as in Example 1, except that the masses of 1,3-propanesulfonic acid lactone (PS) and bromohexane (C) in (2) are 0.1881 g and 0.2244 g, respectively.
[0044] Weigh 0.192 g of OPBI-PS-C and 0.008 g of sBI-Li and dissolve them in 5 mL of DMSO to form a homogeneous mixture. Add the mixture dropwise onto a flat glass plate and dry it in a 60°C oven for 24 h to form a membrane. Then, soak the obtained membrane in 3M sulfuric acid for 24 h and wash it several times with water until a neutral pH is reached to obtain a proton-type membrane. The crosslinking reaction is performed by heating at 80°C in a vacuum oven for 24 h. The obtained membrane is designated OPBI-PS-C / sBI-4.
[0045] The performance parameters of the prepared exchange membrane are as follows: the proton conductivity of the membrane reaches 31.3 mS / cm at 80 °C. -1The water absorption rate was 61.4%, the swelling rate was 5.3%, and the remaining weight after treatment with Fenton's reagent was 89.88% (oxidative stability). The prepared PEM was used to fabricate a membrane electrode (anodine catalyst: IrO2, cathode catalyst: Pt / C). PEM electrolysis of water was tested (40 ℃, electrolyte: 0.2% H2SO4). The current density was 865 mA cm⁻¹ at a voltage of 2V. -2 , at 0.5 A cm -2 After operating at current density for 30 hours, the voltage increased by only 1.9%.
[0046] Example 5
[0047] The preparation of OPBI-PS-C and sBI-Li is similar to that in Example 1, except that the bromoalkane in (2) is replaced with bromoethane.
[0048] Weigh 0.188 g of OPBI-PS-C and 0.012 g of sBI-Li and dissolve them in 5 mL of DMSO to form a homogeneous mixture. Add the mixture dropwise onto a flat glass plate and dry it in a 60°C oven for 24 h to form a membrane. Then, soak the obtained membrane in 3M sulfuric acid for 24 h and wash it several times with water until a neutral pH is reached to obtain a proton-type membrane. The crosslinking reaction is performed by heating at 80°C in a vacuum oven for 24 h. The obtained membrane is designated OPBI-PS-C / sBI-6.
[0049] The performance parameters of the prepared exchange membrane are as follows: the proton conductivity of the membrane reaches 21.2 mS / cm at 80 °C. -1 The water absorption rate was 58.1%, the swelling rate was 5.6%, and the remaining weight after treatment with Fenton's reagent was 92.10% (oxidative stability). The prepared PEM was used to fabricate a membrane electrode (anodine catalyst: IrO2, cathode catalyst: Pt / C). PEM electrolysis of water was tested (40 ℃, electrolyte: 0.2% H2SO4). The current density was 886 mA cm⁻¹ at a voltage of 2V. -2 , at 0.5 A cm -2 After operating at current density for 30 hours, the voltage increased by only 1.4%.
[0050] Comparative Example 1
[0051] The preparation of OPBI-PS-C is the same as in Example 1.
[0052] Weigh 0.2 g of OPBI-PS-C and dissolve it in 5 mL of DMSO to form a homogeneous mixture. Drop the mixture onto a flat glass plate and dry it in an oven at 60 °C for 24 h to form a membrane. The obtained membrane is denoted as OPBI-PS-C / sBI-0.
[0053] The performance parameters of the prepared exchange membrane are as follows: the proton conductivity of the membrane reaches 36.0 mScm at 80 °C. -1 The water absorption rate was 23.5%, the swelling rate was 11.7%, and the remaining weight after treatment with Fenton's reagent was 78.33% (oxidative stability). The prepared PEM was used to fabricate a membrane electrode (anodine catalyst: IrO2, cathode catalyst: Pt / C). PEM electrolysis of water was tested (40 ℃, electrolyte: 0.2% H2SO4). The current density was 1140 mA cm⁻¹ at a voltage of 2V. -2 , at 0.5 A cm -2 After operating at the current density for 30 hours, the voltage increased by 3.0%.
[0054] Comparative Example 2
[0055] The preparation of sBI-Li is the same as in Example 1.
[0056] Dissolve 1.00 g of OPBI in 40 mL of DMSO, add 0.2 g of sodium hydride (NaH) and purge with nitrogen gas. React at 40 °C for 5 hours. Then add 0.310 g of 1,3-propanesulfonate lactone (PS) and continue the reaction at 40 °C for 12 hours. Then, while stirring, pour the mixed solution into acetone. The precipitate is the side-chain sulfonated polybenzimidazole (OPBI-PS). Then dry it in an oven at 60 °C for 24 hours.
[0057] Weigh 0.196 g of OPBI-PS and 0.004 g of sBI-Li and dissolve them in 5 mL of DMSO to form a homogeneous mixture. Add the mixture dropwise onto a flat glass plate and dry it in a 60°C oven for 24 h to form a membrane. Then, soak the obtained membrane in 3M sulfuric acid for 24 h and wash it several times with water until a neutral pH is reached to obtain a proton-type membrane. The crosslinking reaction is performed by heating at 80°C in a vacuum oven for 24 h. The obtained membrane is designated OPBI-PS / sBI-2.
[0058] The performance parameters of the prepared exchange membrane are as follows: the proton conductivity of the membrane reaches 18.9 mScm at 80 °C. -1 The water absorption rate was 85.7%, the swelling rate was 8.5%, and the remaining weight after treatment with Fenton's reagent was 82.88% (oxidative stability). The prepared PEM was used to fabricate a membrane electrode (anodine catalyst: IrO2, cathode catalyst: Pt / C). PEM electrolysis of water was tested (40 ℃, electrolyte: 0.2% H2SO4). The current density was 890 mA cm⁻¹ at a voltage of 2V. -2 , at 0.5 A cm -2After operating at current density for 30 hours, the voltage increased by 2.4%.
[0059] Comparative Example 3
[0060] The preparation of OPBI-PS-C and sBI-Li is the same as in Example 1.
[0061] Weigh 0.196 g of OPBI-PS-C and 0.004 g of sBI-Li and dissolve them in 5 mL of DMSO to form a homogeneous mixture. Drop the mixture onto a flat glass plate and dry it in an oven at 60 °C for 24 h to form a membrane. The obtained membrane is denoted as uncrosslinked OPBI-PS-C / sBI-2.
[0062] The performance parameters of the prepared exchange membrane are as follows:
[0063] The membrane exhibits a proton conductivity of 45.7 mS / cm at 80 °C. -1 The water absorption rate was 37.6%, the swelling rate was 18%, and the remaining weight after treatment with Fenton's reagent was 80.23% (oxidative stability). The prepared PEM was used to fabricate a membrane electrode (anodine catalyst: IrO2, cathode catalyst: Pt / C). PEM electrolysis of water was tested (40 ℃, electrolyte: 0.2% H2SO4). The current density was 1030 mA cm⁻¹ at a voltage of 2V. -2 , at 0.5 A cm -2 After operating at current density for 18 hours, the voltage increased significantly, reaching 23%.
[0064] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A cross-linked hydrophilic-hydrophobic dual-comb sulfonated polybenzimidazole proton exchange membrane, characterized in that, The structural formula of the proton exchange membrane material is shown below: 。 2. A method for preparing a cross-linked hydrophilic-phobic dual-comb sulfonated polybenzimidazole proton exchange membrane according to claim 1, characterized in that, The preparation method steps are as follows: (1) Under a nitrogen atmosphere, the residual air in PPA was removed by mechanical stirring. 3,3'-diaminobenzidine and 4,4'-dicarboxylic acid diphenyl ether were completely dissolved in polyphosphoric acid. The mixture was heated to 140 °C and reacted for 3 hours, and then reacted at 180 °C for 24 hours. After the reaction was completed, the solution was poured into deionized water to cool. The resulting solid was washed with deionized water and neutralized with NaHCO3. Finally, the product was dried in an oven. The polymer was named OPBI. (2) Dissolve OPBI in DMSO, add sodium hydride and purge with nitrogen, react at 40 °C for 5 hours, then add 1,3-propanesulfonic acid lactone and bromoalkane, continue to react at 40 °C for 12 hours, then pour the mixed solution into acetone while stirring, and the precipitate is the hydrophilic / hydrophobic double comb type polybenzimidazole OPBI-PS-C, and then dry it in an oven at 60 °C for 24 hours. (3) Under a nitrogen atmosphere, at a temperature above 80 °C, mechanical stirring was used to remove residual oxygen in the polyphosphoric acid used as a solvent. Then, 3,3'-diaminobenzidine and sodium isophthalic acid-5-sulfonate were added in sequence. After complete dissolution, the temperature was first raised to 140 °C and reacted for 3 h. Then, the temperature was raised to 180 °C and the reaction was continued for 15 h until the reaction solution changed color. The brown solution was poured into deionized water, and the resulting brown powder was thoroughly washed with deionized water. Then, lithium hydroxide was used to neutralize it to obtain sBI-Li. (4) Dissolve OPBI-PS-C and sBI-Li in DMSO, cast the homogeneous mixed solution onto a glass plate, dry it at 60 °C to form a film, then soak the obtained film in sulfuric acid for 24 h, and then wash it with water until neutral pH to obtain a proton-type film. The crosslinking reaction is carried out by heating at 80 °C for 24 h in a vacuum oven to obtain a crosslinked film.
3. The method for preparing the cross-linked hydrophilic-phobic dual-comb sulfonated polybenzimidazole proton exchange membrane according to claim 2, characterized in that, In step (a), the molar ratio of 3,3'-diaminobenzidine to 4,4'-dicarboxylic acid diphenyl ether is 1:1, and the amount of polyphosphoric acid used is more than 10 times the total mass of the monomers.
4. The method for preparing the cross-linked hydrophilic-hydrophobic dual-comb sulfonated polybenzimidazole proton exchange membrane according to claim 2, characterized in that, In step (b), the mass-to-volume ratio of OPBI to DMSO is 1 g: 40 ml; the mass-to-volume ratio of OPBI to sodium hydride is 1: 0.
2.
5. The method for preparing the cross-linked hydrophilic-phobic dual-comb sulfonated polybenzimidazole proton exchange membrane according to claim 2, characterized in that, In step (b), the mass ratio of OPBI, bromoalkane, and 1,3-propanesulfonic acid lactone is 1:0.06-0.2244:0.181-0.310; the bromoalkane is bromohexane or bromoethane.
6. The method for preparing the cross-linked hydrophilic-hydrophobic dual-comb sulfonated polybenzimidazole proton exchange membrane according to claim 2, characterized in that, In step (c), the molar ratio of 3,3'-diaminobenzidine to sodium isophthalic acid-5-sulfonate is 1:2.1, and the amount of polyphosphoric acid used is more than 10 times the total mass of the monomers.
7. The method for preparing the cross-linked hydrophilic-phobic dual-comb sulfonated polybenzimidazole proton exchange membrane according to claim 2, characterized in that, In step (d), the amount of sBI-Li crosslinking agent used is 2-6% of the total mass of sBI-Li and OPBI-PS-C.
8. The method for preparing the cross-linked hydrophilic-hydrophobic dual-comb sulfonated polybenzimidazole proton exchange membrane according to claim 2, characterized in that, In step (d), the concentration of sulfuric acid used for soaking is 3 M.
9. An application of the cross-linked hydrophilic-hydrophobic dual-comb sulfonated polybenzimidazole proton exchange membrane according to claim 1, characterized in that, The cross-linked hydrophilic and hydrophobic dual-comb sulfonated polybenzimidazole proton exchange membrane is used in water electrolysis.