A method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material
By introducing a cross-linked structure into the polybenzimidazole electrolyte membrane, the problems of insufficient oxidation resistance and mechanical strength of PEMFC at high temperatures were solved, and fuel cell performance with high efficiency of proton conduction and high power density at high temperatures was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HEILONGJIANG UNIV
- Filing Date
- 2026-03-25
- Publication Date
- 2026-06-09
AI Technical Summary
Existing proton exchange membrane fuel cell (PEMFC) materials suffer from insufficient oxidation resistance and mechanical strength when pursuing high power density, making it difficult for the membrane to maintain its performance under high loads, especially limiting the application of high-temperature PEMFCs.
A method for preparing cross-linked polybenzimidazole electrolyte membrane material was adopted. By introducing 4,4'-dichlorodiphenyl disulfide into polybenzimidazole to form a cross-linked structure, the antioxidant properties and reactive oxygen free radicals were enhanced, while the proton conduction channels were optimized and the mechanical properties were improved.
Cross-linked polybenzimidazole electrolyte membranes maintain efficient proton transport at high temperatures, significantly improving the peak power density and long-term stability of fuel cells, while also exhibiting significantly enhanced mechanical and antioxidant properties.
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Figure CN122177880A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing an electrolyte membrane material. Background Technology
[0002] Fuel cell technology is a clean energy technology that directly converts the chemical energy of fuel into electrical energy through an electrochemical reaction. Its core principle is the use of hydrogen and oxygen (or air) in the presence of a catalyst to undergo a redox reaction, producing water and releasing electrical energy. This technology can be traced back to the experimental discovery of British scientist William Grove in 1839, but its substantial development began in the mid-20th century with NASA's space applications. Since then, fuel cell technology has gradually developed through continuous exploration and practice, undergoing a long development process from early experimental stages to its current application in multiple fields.
[0003] With the advancement of global carbon neutrality goals, fuel cell technology has experienced explosive growth over the past decade. In terms of materials innovation, catalysts are shifting from high-cost platinum-based materials to non-precious metal catalysts, and electrolyte membranes are diversifying from perfluorosulfonic acid membranes to high-temperature polymer electrolyte membranes and alkaline anion exchange membranes. Applications have expanded from aerospace to transportation (hydrogen fuel cell vehicles), stationary power generation (data center backup power), and portable power supplies. Among these, proton exchange membrane fuel cells (PEMFCs), with their low-temperature efficiency and rapid start-up, are considered a crucial direction for automotive power. However, existing material systems still face a core contradiction: achieving both high power density and long-term robustness simultaneously is difficult. For example, using ultrathin films or highly active catalysts to pursue high power density often exacerbates chemical degradation (insufficient oxidation resistance) and mechanical damage to the membrane during operation, making it difficult to maintain performance under high loads. This contradiction is currently a key bottleneck restricting the wider application of PEMFCs, especially high-temperature PEMFCs. An ideal high-temperature proton exchange membrane needs high proton conductivity, resistance to electron crosstalk with gases, resistance to ·HO and ·HOO radicals, stability at 140-200℃, and good mechanical properties. Therefore, improving these three properties is crucial. Summary of the Invention
[0004] The purpose of this invention is to address the problem that the excellent proton conductivity of existing OPBI membranes is highly dependent on phosphoric acid doping, which leads to decreased antioxidant properties, membrane swelling, decreased mechanical strength, and phosphoric acid loss during long-term operation, thereby affecting the durability and stability of the battery. The invention provides a method for preparing a cross-linked polybenzimidazole electrolyte membrane material that can improve proton conductivity, effectively prevent phosphoric acid loss, and enhance antioxidant properties.
[0005] The present invention discloses a method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material as follows:
[0006] I. Preparation of cross-linked OPBI:
[0007] Polybenzimidazole was dissolved in N,N-dimethylacetamide, and then 4,4-dimethylacetamide was added. ’ The reaction was carried out with dichlorodiphenyl disulfide. After the reaction was completed, the mixture was filtered. The filtrate was poured into deionized water and washed repeatedly to purify it. The precipitated polymer was filtered and dried to obtain cross-linked OPBI.
[0008] II. Preparation of cross-linked membranes:
[0009] Crosslinked OPBI was added to N,N-dimethylacetamide and heated to dissolve, obtaining a polymer solution. This polymer solution was then cast onto a glass plate to form a membrane, which was dried to obtain a crosslinked membrane. The membrane was then immersed in a phosphoric acid solution, removed, and the phosphoric acid solution was wiped off the membrane surface with filter paper to obtain a 4,4-crosslinked membrane. ’ -Dichlorodiphenyl disulfide / polybenzimidazole crosslinked membrane, thus completing the preparation method described above.
[0010] The beneficial effects of this invention are:
[0011] This application constructs an antioxidant cross-linked polybenzimidazole electrolyte membrane. The cross-linked structure effectively inhibits excessive swelling of the membrane under phosphoric acid doping conditions, stabilizes and optimizes the proton conduction channel, and reduces membrane impedance. Simultaneously, the introduced antioxidant unit captures reactive oxygen free radicals generated during fuel cell operation, mitigating membrane chemical degradation and improving structural stability. These synergistic effects enable the membrane to maintain efficient and stable proton transport under high-temperature operating conditions, thereby significantly improving the peak power density of the fuel cell. In terms of fuel cell performance, the OPBI-DFB-15 achieves a peak power density of 669.8 mW / cm² and an electrical conductivity of 132.03 mS / cm². -1 The OPBI-DFB-20 crosslinked membrane exhibited a phosphoric acid retention rate of 83.11% after 100 hours of exposure, demonstrating stronger retention capacity. Hydrogen bonds and increased covalent interactions between 4,4'-dichlorodiphenyl disulfide and the OPBI backbone enhance the membrane's mechanical properties. The crosslinked membrane of this invention combines high power density, long-term robustness, excellent antioxidant properties, and proton conductivity. Attached Figure Description
[0012] Figure 1 Fourier transform infrared spectra of the crosslinked membranes prepared in Examples 1-4 and OPBI;
[0013] Figure 2 Comparative graphs showing the antioxidant properties of the crosslinked films prepared in Examples 1-4 and OPBI;
[0014] Figure 3 The thermal stability curves of the crosslinked films prepared in Examples 1-4 and OPBI are shown.
[0015] Figure 4 Stress-strain curves of the crosslinked films prepared in Examples 1-4 and OPBI without acid soaking are shown.
[0016] Figure 5 The images show the stress-strain curves of the crosslinked films prepared in Examples 1-4 and the OPBI after acid soaking.
[0017] Figure 6 Acid leaching tests were conducted on the crosslinked membranes prepared in Examples 1-4 and on OPBI.
[0018] Figure 7 The cross-linked membranes prepared in Examples 1-4 and the proton conductivity curves of OPBI are shown.
[0019] Figure 8 Battery performance testing of the film-forming electrode prepared from the crosslinked membrane in Example 3. Detailed Implementation
[0020] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.
[0021] Specific Implementation Method 1: The preparation method of an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material in this embodiment is as follows:
[0022] I. Preparation of cross-linked OPBI:
[0023] Polybenzimidazole was dissolved in N,N-dimethylacetamide (DMAc), and then 4,4-dimethylacetamide was added. ’ The reaction was carried out with dichlorodiphenyl disulfide. After the reaction was completed, the mixture was filtered. The filtrate was poured into deionized water and washed repeatedly to purify it. The precipitated polymer was filtered and dried to obtain cross-linked OPBI.
[0024] II. Preparation of cross-linked membranes:
[0025] Crosslinked OPBI was added to DMAc and heated to dissolve, obtaining a polymer solution. This polymer solution was then cast onto a glass plate to form a membrane, which was dried to obtain a crosslinked membrane. The membrane was then immersed in a phosphoric acid solution, removed, and the phosphoric acid solution on the membrane surface was wiped off with filter paper to obtain a 4,4 ’ -Dichlorodiphenyl disulfide / polybenzimidazole crosslinked membrane, thus completing the preparation method described above.
[0026] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the preparation method of polybenzimidazole is as follows: In a 150ml three-necked round-bottom flask, 3,3'-diaminobenzidine and 4,4'-diphenyl ether dicarboxylic acid are dissolved in polyphosphoric acid (PPA). Under nitrogen protection, the mixture is heated and stirred, then heated to 160℃ and stirred continuously until the solution becomes viscous. The solution is then poured into deionized water to obtain the polymer. The polymer is collected and washed with sodium bicarbonate solution until neutral. After drying, it is ground and washed again with sodium bicarbonate solution until neutral to obtain polybenzimidazole (OPBI). Everything else is the same as in Specific Implementation Method One.
[0027] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the mass ratio of 3,3'-diaminobenzidine, 4,4'-diphenyl ether dicarboxylic acid, and polyphosphoric acid is 4-5:5-6:89-90. Everything else is the same as in Specific Implementation Method 1 or 2.
[0028] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the mass concentration of the sodium bicarbonate alkaline solution is 0.2%. Everything else is the same as in Specific Implementation Methods One to Three.
[0029] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: in step one, polybenzimidazole, 4,4 ’ The mass-to-volume ratio of dichlorodiphenyl disulfide and N,N-dimethylacetamide is 0.8 g:0.04 g-0.2 g:15 mL. Other aspects are the same as in any of the specific embodiments one to four.
[0030] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the reaction in step one is carried out at 80°C under a nitrogen atmosphere for 24 hours. Everything else is the same as in Specific Implementation Methods One to Five.
[0031] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the mass-to-volume ratio of crosslinked OPBI to N,N-dimethylacetamide in step two is 1g-1.2g:18mL-21mL. Everything else is the same as in Specific Implementation Methods One to Six.
[0032] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the heating temperature in step two is 80°C. Everything else is the same as in Specific Implementation Methods One to Seven.
[0033] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the mass concentration of the phosphoric acid solution is 85%. Everything else is the same as in Specific Implementation Methods One to Eight.
[0034] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that it involves soaking in a phosphoric acid solution for 48-50 hours. Otherwise, it is the same as Specific Implementation Methods One to Nine.
[0035] The beneficial effects of the present invention are verified using the following embodiments:
[0036] Example 1
[0037] A method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material is carried out according to the following steps:
[0038] I. Preparation of polybenzimidazole:
[0039] In a 150 ml three-necked round-bottom flask, 4.29 g of 3,3'-diaminobenzidine and 5.16 g of 4,4'-diphenyl ether dicarboxylic acid were dissolved in 89 g of PPA. The mixture was heated and stirred under nitrogen protection, and then the temperature was increased to 160 °C while stirring continuously until the solution became viscous. The solution was then poured into deionized water to obtain the polymer. The polymer was collected and washed with a 0.2% sodium bicarbonate alkaline solution until neutral. After drying, it was ground and washed again with sodium bicarbonate alkaline solution until neutral to obtain OPBI.
[0040] II. Preparation of cross-linked OPBI:
[0041] Dissolve 0.8g of OPBI in 15ml of DMAc, then add 0.04g of 4,4 ’ -Dichlorodiphenyl disulfide was reacted at 80°C under a nitrogen atmosphere for 24 hours. After filtration, the filtrate was collected and repeatedly washed and purified in deionized water to precipitate cross-linked OPBI polymer. After filtration and drying, the purification was completed to obtain OPBI-DFB-5.
[0042] III. Preparation of cross-linked membranes:
[0043] 1g of the above crosslinked OPBI polymer was added to 18ml of DMAc and heated to dissolve, obtaining a polymer solution. The polymer solution was then cast onto a glass plate, dried, and a crosslinked membrane was obtained. This membrane was then immersed in a phosphoric acid solution, removed, and the phosphoric acid on the membrane surface was wiped off with filter paper to obtain a 4,4 ’ -Dichlorodiphenyl disulfide / polybenzimidazole crosslinked membrane, thus completing the preparation method described above.
[0044] Example 2
[0045] A method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material is carried out according to the following steps:
[0046] II. Preparation of polybenzimidazole:
[0047] In a 150 ml three-necked round-bottom flask, 4.29 g of 3,3'-diaminobenzidine and 5.16 g of 4,4'-diphenyl ether dicarboxylic acid were dissolved in 89 g of PPA. The mixture was heated and stirred under nitrogen protection, and then the temperature was increased to 160 °C while stirring continuously until the solution became viscous. The solution was then poured into deionized water to obtain the polymer. The polymer was collected and washed with a 0.2% sodium bicarbonate alkaline solution until neutral. After drying, it was ground and washed again with sodium bicarbonate alkaline solution until neutral to obtain OPBI.
[0048] II. Preparation of cross-linked OPBI:
[0049] Dissolve 0.8g of OPBI in 15ml of DMAc, then add 0.08g of 4,4 ’ -Dichlorodiphenyl disulfide was reacted at 80°C under a nitrogen atmosphere for 24 hours. After filtration, the filtrate was collected and repeatedly washed and purified in deionized water to precipitate cross-linked OPBI polymer. After filtration and drying, the purification was completed to obtain OPBI-DFB-10.
[0050] III. Preparation of cross-linked membranes:
[0051] 1.06 g of the above crosslinked OPBI was added to 19 ml of DMAc and heated to dissolve, obtaining a polymer solution. The polymer solution was then cast onto a glass plate to form a membrane, which was dried to obtain a crosslinked membrane. The membrane was then soaked in a phosphoric acid solution for 48 h. After removal, the phosphoric acid on the membrane surface was wiped off with filter paper to obtain a 4,4 ’ -Dichlorodiphenyl disulfide / polybenzimidazole crosslinked membrane, thus completing the preparation method described above.
[0052] Example 3
[0053] A method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material is carried out according to the following steps:
[0054] III. Preparation of polybenzimidazole:
[0055] In a 150 ml three-necked round-bottom flask, 4.29 g of 3,3'-diaminobenzidine and 5.16 g of 4,4'-diphenyl ether dicarboxylic acid were dissolved in 89 g of PPA. The mixture was heated and stirred under nitrogen protection, and then the temperature was increased to 160 °C while stirring continuously until the solution became viscous. The solution was then poured into deionized water to obtain the polymer. The polymer was collected and washed with a 0.2% sodium bicarbonate alkaline solution until neutral. After drying, it was ground and washed again with sodium bicarbonate alkaline solution until neutral to obtain OPBI.
[0056] II. Preparation of cross-linked OPBI polymers:
[0057] Dissolve 0.8g of OPBI in 15ml of DMAc, then add 0.12g of 4,4 ’-Dichlorodiphenyl disulfide was reacted at 80°C under a nitrogen atmosphere for 24 hours. After filtration, the filtrate was collected and repeatedly washed and purified in deionized water to precipitate cross-linked OPBI polymer. After filtration and drying, the cross-linked polymer OPBI-DFB-15 was obtained.
[0058] III. Preparation of cross-linked membranes:
[0059] 1.1 g of the above crosslinked OPBI polymer was added to 20 ml of DMAc and heated to dissolve, obtaining a polymer solution. The polymer solution was then cast onto a glass plate to form a membrane, which was then dried to obtain a crosslinked membrane. The membrane was then immersed in 85% phosphoric acid solution, and after removal, the phosphoric acid on the membrane surface was wiped off with filter paper to obtain a 4,4 ’ -Dichlorodiphenyl disulfide / polybenzimidazole crosslinked membrane, thus completing the preparation method described above.
[0060] Example 4
[0061] A method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material is carried out according to the following steps:
[0062] IV. Preparation of polybenzimidazole:
[0063] In a 150 ml three-necked round-bottom flask, 4.29 g of 3,3'-diaminobenzidine and 5.16 g of 4,4'-diphenyl ether dicarboxylic acid were dissolved in 89 g of PPA. The mixture was heated and stirred under nitrogen protection, and then the temperature was increased to 160 °C while stirring continuously until the solution became viscous. The solution was then poured into deionized water to obtain the polymer. The polymer was collected and washed with a 0.2% sodium bicarbonate alkaline solution until neutral. After drying, it was ground and washed again with sodium bicarbonate alkaline solution until neutral to obtain OPBI.
[0064] II. Preparation of cross-linked OPBI polymers:
[0065] Dissolve 0.8g of OPBI in 15ml of DMAc, then add 0.16g of 4,4 ’ -Dichlorodiphenyl disulfide was reacted at 80°C under a nitrogen atmosphere for 24 hours. After filtration, the filtrate was collected and repeatedly washed and purified in deionized water to precipitate cross-linked OPBI polymer. After filtration and drying, the cross-linked polymer OPBI-DFB-20 was obtained.
[0066] III. Preparation of cross-linked membranes:
[0067] 1.2 g of the above crosslinked OPBI polymer was added to 21 ml of DMAc and heated to dissolve, obtaining a polymer solution. The polymer solution was then cast onto a glass plate to form a membrane, which was then dried to obtain a crosslinked membrane. The membrane was then immersed in a phosphoric acid solution, removed, and the phosphoric acid on the membrane surface was wiped off with filter paper to obtain a 4,4 ’-Dichlorodiphenyl disulfide / polybenzimidazole crosslinked membrane, thus completing the preparation method described above.
[0068] Comparative Example 1
[0069] This comparative example uses the original OPBI membrane.
[0070] like Figure 1 As shown in the Fourier transform infrared spectrum, at 1600 cm⁻¹ -1 1490cm -1 680cm -1 497cm -1 (This location is not SS, it should be around 497, modify the infrared image) Signal peaks appeared at this position, which are attributed to carbon-nitrogen double bonds, aromatic ether bonds, carbon-sulfur bonds, and 4,4 ’ - Characteristic absorption peaks of disulfide bonds in dichlorodiphenyl disulfide. This further indicates that the 4,4-disulfide prepared in this work... ’ The high-temperature proton exchange membrane material OPBI-DFB-X, consisting of dichlorodiphenyl disulfide / polybenzimidazole, has been successfully prepared.
[0071] like Figure 2 The antioxidant properties of OPBI membranes and cross-linked membranes were tested. After adding Fenton's reagent, the cross-linked membrane materials all exhibited superior oxidation stability compared to pure OPBI electrolyte membranes. When the cross-linking agent content reached 20%, the mass loss was less than 5% after 200 hours of oxidation, significantly better than pure OPBI. Experimental data showed that the addition of 4,4'-... ’ -Dichlorodiphenyl disulfide significantly enhances the antioxidant properties of the membrane.
[0072] like Figure 3 Thermal stability curves are shown in the graphs: OPBI and 4,4 ’ Thermal analysis of the dichlorodiphenyl disulfide / polybenzimidazole crosslinked membrane, measured from 100℃ to 800℃, revealed two weight loss steps. The first weight loss step, between 200-400℃, primarily resulted from residual solvent within the membrane. The second weight loss step, occurring after 500℃, was mainly due to azole ring opening, main chain breakage, and main chain carbonization. Figure 3 It can be seen that the thermal stability of cross-linked OPBI is significantly better than that of pure OPBI, especially with the addition of 4,4- ’ -Dichlorodiphenyl disulfide significantly improved the thermal stability of the membrane.
[0073] like Figure 4The figures show the stress-strain curves of pure OPBI and cross-linked membranes with different degrees of cross-linking. The figures demonstrate that the addition of a certain amount of cross-linking agent can improve the mechanical properties of the polymer electrolyte membrane material. The addition of a large amount of cross-linking agent results in a loss of some mechanical properties, mainly because the cross-linking agent binds to the NH bonds on the imidazole ring, which to some extent disrupts the hydrogen bond interactions between OPBI segments. However, its tensile strength still meets the requirements for use as a high-temperature proton exchange membrane.
[0074] like Figure 5 The figures show the stress-strain curves after phosphoric acid doping. The elongation at break of the OPBI-DFB-5%, OPBI-DFB-10%, OPBI-DFB-15%, and OPBI-DFB-20% crosslinked films is superior to that of the pure OPBI film. This is mainly attributed to the presence of the crosslinking agent, which increases the interlayer spacing within the film, thereby improving the elongation at break. Meanwhile, the presence of the crosslinking agent has little effect on the tensile strength of the polymer electrolyte membrane material.
[0075] like Figure 6 The phosphoric acid retention capacity of polymer electrolyte membrane materials with different degrees of crosslinking was studied by monitoring the weight change of the membrane at different test times under conditions of 80℃ and 40% relative humidity. After 100 hours of exposure under the above conditions, the phosphoric acid doped membrane of OPBI-DFB-20 had a retention rate of 83.11%, which was higher than that of the pure OPBI membrane. This is because the presence of the crosslinking agent creates steric hindrance within the polymer electrolyte membrane material, effectively preventing the loss of phosphoric acid. The crosslinked membrane exhibits both increased phosphoric acid absorption and higher phosphoric acid retention capacity.
[0076] like Figure 7 As shown in the proton conductivity curve, the proton conductivity of all polymer electrolyte membranes increases with increasing temperature. The peak proton conductivity of the OPBI membrane at 180℃ is 77.1 mS / cm. -1 At the same temperature, the OPBI-DFB-15 membrane exhibits higher conductivity: 132.0 mS / cm. -1 This indicates that 4,4 ’ The presence of dichlorodiphenyl disulfide crosslinking agent effectively improves the proton conductivity of polymer electrolyte membrane materials.
[0077] like Figure 8As shown, OPBI-DFB-15 was doped with phosphoric acid to prepare a film electrode (MEA), and the practical application of HT-PEMFC was tested. Under non-humidified H2 / O2 and no back pressure conditions, the power density and polarization curves of OPBI-DFB-15 were measured at 80℃, 120℃, 160℃, 180℃, and 200℃. The peak power density of OPBI-DFB-15 at 180℃ reached 669.8 mW / cm², and the open-circuit voltage was around 0.95V, indicating that the membrane has good hermeticity.
Claims
1. A method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material, characterized in that, The preparation method is as follows: I. Preparation of cross-linked OPBI: Polybenzimidazole was dissolved in N,N-dimethylacetamide, and then 4,4-dimethylacetamide was added. ’ The reaction was carried out with dichlorodiphenyl disulfide. After the reaction was completed, the mixture was filtered. The filtrate was poured into deionized water and washed repeatedly to purify it. The precipitated polymer was filtered and dried to obtain cross-linked OPBI. II. Preparation of cross-linked membranes: Crosslinked OPBI was added to N,N-dimethylacetamide and heated to dissolve, obtaining a polymer solution. This polymer solution was then cast onto a glass plate to form a membrane, which was dried to obtain a crosslinked membrane. The membrane was then immersed in a phosphoric acid solution, removed, and the phosphoric acid solution was wiped off the membrane surface with filter paper to obtain a 4,4-crosslinked membrane. ’ -Dichlorodiphenyl disulfide / polybenzimidazole crosslinked membrane, thus completing the preparation method described above.
2. The method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material according to claim 1, characterized in that, The preparation method of polybenzimidazole is as follows: In a 150ml three-necked round-bottom flask, 3,3'-diaminobenzidine and 4,4'-diphenyl ether dicarboxylic acid are dissolved in polyphosphoric acid. The mixture is heated and stirred under nitrogen protection, and then the temperature is increased to 160℃ and stirred continuously until the solution becomes viscous. Then it is poured into deionized water to obtain the polymer. The polymer is collected and washed with sodium bicarbonate alkaline solution until neutral. After drying, it is ground to obtain polybenzimidazole.
3. The method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material according to claim 2, characterized in that, The mass ratio of 3,3'-diaminobenzidine, 4,4'-diphenyl ether dicarboxylic acid and polyphosphoric acid is 4-5:5-6:89-90.
4. The method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material according to claim 2, characterized in that, The mass concentration of the sodium bicarbonate alkaline solution is 0.2%.
5. The method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material according to claim 1, characterized in that, In step one, polybenzimidazole, 4,4 ’ The mass-to-volume ratio of dichlorodiphenyl disulfide and N,N-dimethylacetamide is 0.8 g: 0.04 g - 0.2 g: 15 mL.
6. The method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material according to claim 1, characterized in that, In step one, the reaction is carried out at 80°C under a nitrogen atmosphere for 24 hours.
7. The method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material according to claim 1, characterized in that, In step two, the mass-to-volume ratio of crosslinked OPBI to N,N-dimethylacetamide is 1g-1.2g:18mL-21mL.
8. The method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material according to claim 1, characterized in that, The heating temperature in step two is 80℃.
9. The method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material according to claim 1, characterized in that, The mass concentration of the phosphoric acid solution is 85%.
10. The method for preparing an antioxidant-enhanced cross-linked polybenzimidazole electrolyte membrane material according to claim 1, characterized in that, Soak in phosphoric acid solution for 48-50 hours.