A method for improving the oxidative stability of proton exchange membrane surface in fuel cells

Abstract

This invention relates to the field of fuel cell technology, specifically to a method for improving the oxidation stability of a proton exchange membrane (PEM) surface in a fuel cell. The method includes: S1, preparing a composite material PEM; S2, modifying the PEM; and S3, applying a coating. This invention enhances the mechanical properties of the PEM by preparing a composite material. Using MOF nanofibers and silica sol significantly improves the mechanical strength and flexibility of the PEM, allowing it to maintain performance at high temperatures and improving thermal stability. The modification treatment introduces specific amino functional groups onto the surface of the MOF-containing membrane, enhancing its proton conductivity and improving its oxidation stability. The coating further improves the membrane's durability and stability, maintaining high efficiency during long-term use. Constructing a porous free radical quenching layer on the membrane surface enhances the PEM's antioxidant properties.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more specifically to a method for improving the oxidation stability of the proton exchange membrane surface in a fuel cell. Background Technology

[0002] As a highly efficient and clean energy conversion device, fuel cells rely heavily on a proton exchange membrane (PEM) as one of their core components. The primary function of the PEM is to conduct protons between the anode and cathode while blocking electrons, thereby generating electricity. However, a significant challenge facing PEMs during use is their insufficient surface oxidative stability, which directly impacts the lifespan and performance of the fuel cell.

[0003] The primary proton exchange membrane used in existing fuel cells is the perfluorosulfonic acid membrane (Nafion), which is widely used due to its excellent proton conductivity and chemical stability. Developed by DuPont, Nafion membranes are currently the most widely used commercially available proton exchange membrane material. However, the performance of Nafion membranes degrades at high temperatures, prompting the exploration of alternative materials and solutions.

[0004] Fuel cells generate free radicals during operation, which can attack proton exchange membranes (PEMs), leading to membrane degradation and performance decline. Therefore, improving the surface oxidation stability of PEMs is an important research direction. Currently, the challenges in PEM antioxidant stability technology include how to effectively prevent the formation and attack of free radicals, and how to enhance its chemical stability without sacrificing the membrane's proton conductivity. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for improving the oxidative stability of the proton exchange membrane surface in a fuel cell.

[0006] The technical solution of this invention is: a method for improving the oxidation stability of the proton exchange membrane surface in a fuel cell, comprising the following steps:

[0007] S1. Preparation of composite proton exchange membranes

[0008] S1-1. MOF nanofibers are immersed in a 1-10 wt% ammonium polyphosphate solution and mixed evenly at a ratio of 2:4-6 g / ml to obtain a composite material.

[0009] S1-2. By mass percentage, add 5-40% silica sol solution to the composite material, mix evenly to obtain composite sol solution; pour the composite sol solution into a proton exchange membrane mold to form, and obtain the membrane material after demolding;

[0010] S1-3. The membrane material is hot-pressed and sintered at a temperature of 60-120℃ to obtain a proton exchange membrane;

[0011] S2, Proton Exchange Membrane Modification Treatment

[0012] The proton exchange membrane is pretreated, then immersed in a 0.5–1.5 wt% APTES solution for 0.5–1 h, and then immersed in a 0.5–1.5 wt% HMDS solution for 0.5–1 h. The pretreated proton exchange membrane is then removed and placed in an oven at 70–120 °C for 1–3 h. The solvents for the APTES and HMDS solutions are ethanol; the APTES solution is a γ-aminopropyltriethoxysilane solution, and the HMDS solution is a hexamethyldisilazane solution.

[0013] S3, Coating Treatment

[0014] CeO2 nanoparticles were dispersed in ethanol to obtain a CeO2 ethanol solution with a mass concentration of 0.5-1.5%. The CeO2 ethanol solution was uniformly coated on the surface of the modified proton exchange membrane. The coated proton exchange membrane was dried and then heat-treated to obtain a fuel cell proton exchange membrane with high surface oxidation stability.

[0015] Explanation: The preparation of proton exchange membranes using composite materials enhances the membrane's mechanical properties. APTES treatment introduces amino groups, improving proton conductivity. HMDS treatment further improves the membrane's chemical stability, particularly its resistance to acidic or alkaline environments. Silanization and isocyanate crosslinking enhance the membrane's mechanical strength, helping it resist physical stress and abrasion during operation. Modification treatments also improve the membrane's proton conductivity. Using CeO2 as a free radical quencher significantly improves the proton exchange membrane's antioxidant properties, extending the fuel cell's lifespan. Coating treatments significantly improve the membrane's antioxidant properties and durability, further extending the fuel cell's lifespan.

[0016] Furthermore, the MOF nanofibers described in S1-1 are hollow fibers with a length of 30–90 nm, an outer diameter of 8–15 nm, and an inner diameter of 5–10 nm.

[0017] Explanation: The hollow structure of MOF nanofibers can provide shorter ion transport paths, thereby accelerating proton migration and improving the ion conductivity of the membrane. The shell structure of MOF nanofibers can withstand external pressure, while the internal cavity can absorb stress to a certain extent, improving the toughness and rupture resistance of the membrane. It also helps with heat transfer within the material, improving the thermal stability of the membrane under high-temperature operation. When mixed with ammonium polyphosphate solution, the ammonium polyphosphate enters the hollow structure of MOF nanofibers, further enhancing the proton transport efficiency after membrane preparation.

[0018] Further, the mixing method of MOF nanofibers and ammonium polyphosphate solution in S1-1 is as follows: ammonium polyphosphate is dissolved in deionized water according to the formula concentration ratio to obtain ammonium polyphosphate solution; then MOF nanofibers are added into the ammonium polyphosphate solution for stirring and impregnation, and an ultrasonic oscillator is used for oscillation during stirring.

[0019] Explanation: The cavitation effect generated by the ultrasonic oscillator can more uniformly disperse MOF nanofibers in the ammonium polyphosphate solution, avoiding agglomeration. This uniform dispersion helps improve the homogeneity and performance of the subsequent composite material; the ultrasonic oscillator can promote better wetting of the MOF nanofiber surface by the ammonium polyphosphate solution, allowing the solution to fully penetrate into the microstructure of the fiber, thereby improving the interaction and adhesion between the two.

[0020] Furthermore, the stirring time is 1–3 h, the stirring speed is 200–300 r / min, the ultrasonic oscillation frequency is 20–40 kHz, and the impregnation time is 5–20 h.

[0021] Note: A moderate stirring speed helps achieve uniform dispersion of MOF nanofibers in the solution, avoiding excessive shear force that could damage the fiber structure. A stirring speed of 200–300 r / min effectively mixes the fibers without damaging them. An ultrasonic oscillator, operating in the 20–40 kHz frequency range, generates cavitation, which helps break up fiber aggregation and promotes uniform dispersion in the solution. Furthermore, the mechanical vibration of ultrasound accelerates solute diffusion and improves reaction efficiency. A longer impregnation time allows the ammonium polyphosphate solution to fully penetrate the internal structure of the MOF nanofibers, ensuring a tight bond between them.

[0022] Further, the method for pretreating the proton exchange membrane described in S2 is as follows: the proton exchange membrane is soaked and cleaned in an ethanol or acetone solution with a purity of 95-99% for 10-30 minutes, then soaked and cleaned in deionized water for 10-20 minutes, and then the surface is dried with nitrogen gas.

[0023] Note: Immersion cleaning with 95-99% pure ethanol or acetone solution effectively removes grease, organic residues, and other organic contaminants from the proton exchange membrane surface. Immersion cleaning with deionized water further removes inorganic salts, dust particles, and other inorganic impurities that were not removed in the previous step. The increased surface energy of the proton exchange membrane after cleaning facilitates subsequent modification treatments. A high surface energy surface provides more active sites, enhancing the interaction with the modifier and thus improving the modification effect. A clean surface facilitates the uniform coating and adhesion of the modifier, improving the stability and consistency of the modified layer. This ensures good contact between the modifier and the membrane surface, avoiding uneven modification or failure due to contamination. Nitrogen drying during pretreatment quickly removes moisture, preventing recontamination of the membrane surface by airborne pollutants and avoiding potential side reactions caused by moisture.

[0024] Furthermore, the CeO2 nanoparticles described in S3 are dispersed in an ethanol solution with a purity of 99-99.9% using an ultrasonic processor with a power of 200-300W and a dispersion time of 20-40min.

[0025] Explanation: Ultrasonic processors can generate numerous high-pressure and low-pressure zones in liquids. The alternating action of these zones can effectively break up the agglomeration of CeO2 nanoparticles, reduce particle size, and thus improve dispersion efficiency.

[0026] Furthermore, the coating method described in S3 is as follows: the modified proton exchange membrane is placed on a spin coater, and a CeO2 ethanol solution is sprayed onto the surface of the modified proton exchange membrane to ensure uniform contact between the membrane surface and the solution. The rotation speed of the spin coater is 500-1000 rpm, and the coating time is 20-30 s.

[0027] Explanation: The spin coating apparatus uses the centrifugal force generated by high-speed rotation to evenly distribute the CeO2 ethanol solution on the surface of the proton exchange membrane, forming a coating of uniform thickness. This helps to improve the overall performance and consistency of the membrane.

[0028] Furthermore, the drying process described in S3 is as follows: the coated proton exchange membrane is placed in an oven and dried at 80-120°C for 2-4 hours to ensure that CeO2 is completely cured on the membrane surface.

[0029] Note: Within a temperature range of 80–120℃, the solvent can evaporate rapidly, effectively removing the ethanol solvent from the coating and ensuring a tight bond between the CeO2 nanoparticles and the membrane surface. Appropriate temperature can accelerate the curing process of the CeO2 nanoparticles on the membrane surface, forming a stable coating. This helps improve the overall mechanical strength and chemical stability of the membrane.

[0030] Furthermore, the heat treatment temperature in S3 is 200–400°C, and the heat treatment time is 1–2 hours.

[0031] Note: Appropriate heat treatment temperature helps the chemical bonding between CeO2 nanoparticles and their carrier proton exchange membrane, thereby improving the adhesion and wear resistance of the coating; it can also promote the rearrangement of CeO2 nanoparticles on the membrane surface to form a more dense and ordered structure, which helps to improve the ion conduction efficiency and mechanical strength of the membrane.

[0032] The beneficial effects of this invention are:

[0033] This invention prepares proton exchange membranes using composite materials, enhancing the membrane's mechanical properties. The use of MOF nanofibers and silica sol significantly improves the mechanical strength and flexibility of the proton exchange membrane. The hot-pressing sintering process helps improve the membrane's thermal and chemical stability, allowing it to maintain performance even at high temperatures. Modification treatment introduces specific amino functional groups onto the surface of the MOF-containing membrane, enhancing its proton conductivity and stability. Coating further improves the membrane's durability and stability, ensuring high efficiency during long-term use. Constructing a porous free radical quenching layer on the membrane surface reduces free radical concentration, slows down membrane degradation, and improves the proton exchange membrane's antioxidant properties. Attached Figure Description

[0034] Figure 1 These are bar charts showing the proton conductivity test results of samples from Examples 1-9 and Comparative Examples 1-5 of this invention.

[0035] Figure 2 These are bar charts showing the high-temperature resistance test results of samples from Examples 1-9 and Comparative Examples 1-5 of this invention;

[0036] Figure 3 These are bar charts showing the lifespan performance tests of samples from Examples 1-9 and Comparative Examples 1-5 of the present invention. Detailed Implementation

[0037] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0038] Example 1:

[0039] A method for improving the oxidative stability of a proton exchange membrane surface in a fuel cell includes the following steps:

[0040] S1. Preparation of composite proton exchange membranes

[0041] S1-1. MOF nanofibers are soaked in a 5 wt% ammonium polyphosphate solution and mixed evenly at a ratio of 2:5 g / ml to obtain a composite material.

[0042] The MOF nanofibers are hollow fibers with a length of 60 nm, an outer diameter of 11.5 nm, and an inner diameter of 7.5 nm.

[0043] The method for mixing MOF nanofibers with ammonium polyphosphate solution is as follows: ammonium polyphosphate is dissolved in deionized water according to the formula concentration ratio to obtain ammonium polyphosphate solution; then MOF nanofibers are added to the ammonium polyphosphate solution for stirring and impregnation, and ultrasonic oscillator is used for stirring; the stirring time is 2h, the stirring speed is 250r / min, the ultrasonic oscillation frequency is 30kHz, and the impregnation time is 12.5h.

[0044] S1-2. By mass percentage, add 22.5% silica sol solution to the composite material, mix evenly to obtain a composite sol solution; pour the composite sol solution into a proton exchange membrane mold to form, and obtain the membrane material after demolding;

[0045] S1-3. The membrane material is hot-pressed and sintered at a temperature of 90℃ to obtain a proton exchange membrane;

[0046] S2, Proton Exchange Membrane Modification Treatment

[0047] The proton exchange membrane was pretreated, then immersed in a 1 wt% APTES solution for 0.75 h, followed by an immersion in a 1 wt% HMDS solution for 0.75 h. The pretreated membrane was then placed in an oven and baked at 95°C for 2 h. The pretreatment method involved immersing the membrane in a 97% ethanol or acetone solution for 20 min, followed by immersion in deionized water for 15 min, and then drying the surface with nitrogen. Ethanol was used as the solvent in both the APTES and HMDS solutions.

[0048] S3, Coating Treatment

[0049] CeO2 nanoparticles were dispersed in ethanol to obtain a 1% (w / w) CeO2 ethanol solution. The CeO2 ethanol solution was uniformly coated onto the surface of a modified proton exchange membrane. The coated proton exchange membrane was dried and then heat-treated to obtain a fuel cell proton exchange membrane with high surface oxidation stability. The CeO2 nanoparticles were dispersed in a 99.5% pure ethanol solution using an ultrasonic processor with a power of 250W for 30 minutes. The coating method was as follows: the modified proton exchange membrane was placed on a spin coater, and the CeO2 ethanol solution was sprayed onto the surface of the modified proton exchange membrane to ensure uniform contact between the membrane surface and the solution. The spin coater rotated at 750 rpm for 25 seconds. The drying method was as follows: the coated proton exchange membrane was placed in an oven and dried at 100°C for 3 hours. The heat treatment temperature was 300°C, and the heat treatment time was 1.5 hours.

[0050] Example 2: This example is basically the same as Example 1, except that MOF nanofibers are soaked in a 1wt% ammonium polyphosphate solution and mixed evenly at a ratio of 2:4 g / ml to obtain a composite material.

[0051] Example 3: This example is basically the same as Example 1, except that MOF nanofibers are soaked in a 10wt% ammonium polyphosphate solution and mixed evenly at a ratio of 2:6 g / ml to obtain a composite material.

[0052] Example 4: This example is basically the same as Example 1, except that the stirring time is 1 hour, the stirring speed is 200 r / min, the ultrasonic oscillation frequency is 20 kHz, and the impregnation time is 5 hours; 5% of the total mass of the composite material is added to the composite material and mixed evenly to obtain a composite sol; the membrane material is hot-pressed and sintered at a temperature of 60°C to obtain a proton exchange membrane.

[0053] Example 5: This example is basically the same as Example 1, except that the proton exchange membrane is pretreated by soaking it in a 1.5 wt% APTES solution for 1 hour, and then the pretreated proton exchange membrane is placed in an oven and baked at 120°C for 3 hours. The method of pretreatment of the proton exchange membrane is as follows: the proton exchange membrane is soaked and cleaned with a 99% pure ethanol or acetone solution for 30 minutes, then soaked and cleaned with deionized water for 20 minutes, and then the surface is dried with nitrogen.

[0054] Example 6: This example is basically the same as Example 1, except that the proton exchange membrane is pretreated by soaking it in 0.5 wt% APTES solution for 0.5 h and then soaking it in 0.5 wt% HMDS solution for 0.5 h. Then, the pretreated proton exchange membrane is taken out and placed in an oven and baked at 70°C for 1 h. The method of pretreatment of the proton exchange membrane is as follows: the proton exchange membrane is soaked and cleaned with 95% pure ethanol or acetone solution for 10 min, then soaked and cleaned with deionized water for 10 min, and then the surface is dried with nitrogen.

[0055] Example 7: This example is basically the same as Example 1, except that CeO2 nanoparticles are dispersed in ethanol to obtain a CeO2 ethanol solution with a mass concentration of 1.5%; the CeO2 nanoparticles are dispersed in a 99.9% pure ethanol solution using an ultrasonic processor with a power of 300W for a dispersion time of 40 minutes; the coating method is as follows: the modified proton exchange membrane is placed on a spin coater, and the CeO2 ethanol solution is sprayed onto the surface of the modified proton exchange membrane to ensure uniform contact between the membrane surface and the solution; the spin coater rotates at 1000 rpm for a coating time of 30 seconds; the coated proton exchange membrane is placed in an oven and dried at 120°C for 4 hours; the heat treatment temperature is 400°C for a heat treatment time of 2 hours.

[0056] Example 8: This example is basically the same as Example 1, except that CeO2 nanoparticles are dispersed in ethanol to obtain a CeO2 ethanol solution with a mass concentration of 0.5%; the CeO2 nanoparticles are dispersed in a 99% pure ethanol solution using an ultrasonic processor with a power of 200W for a dispersion time of 20 minutes; the coating method is as follows: the modified proton exchange membrane is placed on a spin coater, and the CeO2 ethanol solution is sprayed onto the surface of the modified proton exchange membrane to ensure uniform contact between the membrane surface and the solution; the spin coater rotates at 500 rpm for a coating time of 20 seconds; the coated proton exchange membrane is placed in an oven and dried at 80°C for 2 hours; the heat treatment temperature is 200°C for a heat treatment time of 1 hour.

[0057] Example 9: This example is basically the same as Example 1, except that the MOF nanofibers are hollow fibers with a length of 30 nm, an outer diameter of 8 nm, and an inner diameter of 5 nm.

[0058] Example 10: This example is basically the same as Example 1, except that the MOF nanofibers are hollow fibers with a length of 90 nm, an outer diameter of 15 nm, and an inner diameter of 10 nm.

[0059] Comparative Example 1: Referring to Example 1, without performing S1, the perfluorosulfonic acid membrane was directly used for modification and coating treatment.

[0060] Comparative Example 2: Referring to Example 1, no modification treatment was performed.

[0061] Comparative Example 3: Referring to Example 1, no coating treatment was performed.

[0062] Comparative Example 4: Referring to Example 1, the proton exchange membrane was pretreated, then soaked in 0.4 wt% APTES solution for 0.2 h, and then soaked in 2 wt% HMDS solution for 3 h; then the treated proton exchange membrane was taken out and placed in an oven and baked at 150°C for 0.5 h.

[0063] Comparative Example 5: Referring to Example 1, CeO2 nanoparticles were dispersed in ethanol to obtain a CeO2 ethanol solution with a mass concentration of 0.4%; the CeO2 nanoparticles were dispersed in an ethanol solution with a purity of 99-99.9% using an ultrasonic processor with a power of 400W for a dispersion time of 10 min; the coating method was as follows: the modified proton exchange membrane was placed on a spin coater, and the CeO2 ethanol solution was sprayed onto the surface of the modified proton exchange membrane to ensure uniform contact between the membrane surface and the solution; the rotation speed of the spin coater was 1500 rpm, and the coating time was 40 s; the coated proton exchange membrane was placed in an oven and dried at 150°C for 1 h; the heat treatment temperature was 500°C, and the heat treatment time was 0.5 h.

[0064] To investigate the performance of proton exchange membranes in fuel cells treated in Examples 1-9 and Control Examples 1-5, the main materials were determined according to the experimental formulation, and 13 sets of samples were obtained for testing. The specific investigation is as follows:

[0065] 1. Investigating the effect of the ratio of MOF nanofibers to ammonium polyphosphate solution on the performance of proton exchange membranes in fuel cells:

[0066] like Figures 1-3 As shown in the comparison of Examples 1 to 3, it can be seen that Example 1 has better overall performance. Changing the ratio of MOF nanofibers and ammonium polyphosphate solution will have a certain impact on the prepared fuel cell proton exchange membrane samples. Among them, the fuel cell proton exchange membrane prepared using the process parameter values ​​of Example 1 has the best overall performance.

[0067] 2. Investigate the impact of proton exchange membrane fabrication process on the performance of proton exchange membranes in fuel cells:

[0068] like Figures 1-3As shown, a comparison of Examples 1, 4, and 5 reveals that Example 1 exhibits the best overall performance; Example 5 demonstrates superior proton conductivity and lifespan compared to Example 4; Example 4 exhibits higher high-temperature resistance than Example 5; and altering the process parameters for ion exchange membrane preparation can significantly impact sample performance. Among these, the fuel cell proton exchange membrane prepared with process parameters closer to those of Example 1 demonstrates the best overall performance.

[0069] like Figures 1-3 As shown, a comparison between Example 1 and Control Example 1 reveals that the overall performance of Example 1 is significantly better than that of Control Example 1. The ion exchange membrane prepared using this method can exhibit better proton conductivity, high-temperature resistance, and service life after subsequent processing.

[0070] 3. Investigate the effect of modification treatment process on the performance of proton exchange membrane in fuel cells:

[0071] like Figures 1-3 As shown, a comparison of Examples 1, 6, and 7 reveals that the fuel cell proton exchange membrane prepared according to the method of Example 1 has the best overall performance, and the overall performance of Example 6 is better than that of Example 7. This indicates that the process parameters of the modification treatment can have a certain impact on the performance of the fuel cell proton exchange membrane, and controlling the appropriate ratio can improve its proton conductivity and surface oxidation stability.

[0072] As can be seen from the comparison between Example 1 and Comparative Examples 2 and 4, the proton conductivity of Example 1 is significantly better than that of Comparative Examples 2 and 4. The modification treatment operation and the change of its process parameter range have a significant impact on the proton exchange membrane of the fuel cell. The proton exchange membrane prepared using the parameter range of this scheme has better overall performance.

[0073] 4. Investigate the impact of coating treatment process on the performance of proton exchange membrane in fuel cells:

[0074] like Figures 1-3 As shown, comparing Examples 1, 8, and 9, it can be seen that Example 9 has the best proton conductivity, the fuel cell proton exchange membrane treated according to the method of Example 1 has the best high-temperature resistance, the coating process parameters have a certain impact on the performance of fuel cell proton exchange membrane, but the effect is not obvious, and the method parameters used in Example 1 are the best.

[0075] Compared with Comparative Example 3, Example 1 showed significant differences in various performance characteristics and a significantly shorter service life. Compared with Comparative Example 5, the proton conductivity was not significantly different, but the service life was significantly shorter. It can be seen that the coating treatment method and the change in the range of process parameters have a significant impact on the service life of the proton exchange membrane.

Claims

1. A method for improving the oxidative stability of the proton exchange membrane surface in a fuel cell, characterized in that, Includes the following steps: S1. Preparation of composite proton exchange membranes S1-1. MOF nanofibers are soaked in a 1-10 wt% ammonium polyphosphate solution and mixed evenly at a ratio of 2:4-6 g / ml to obtain a composite material. S1-2. By mass percentage, add 5-40% silica sol solution to the composite material, mix evenly to obtain composite sol solution; pour the composite sol solution into a proton exchange membrane mold to form, and obtain the membrane material after demolding; S1-3. The membrane material is hot-pressed and sintered at a temperature of 60-120℃ to obtain a proton exchange membrane; S2, Proton Exchange Membrane Modification Treatment The proton exchange membrane is pretreated, then immersed in a 0.5–1.5 wt% APTES solution for 0.5–1 h, and then immersed in a 0.5–1.5 wt% HMDS solution for 0.5–1 h. The treated proton exchange membrane is then removed and placed in an oven and baked at 70–120 °C for 1–3 h. The solvents for the APTES and HMDS solutions are ethanol. S3, Coating Treatment CeO2 nanoparticles were dispersed in ethanol to obtain a CeO2 ethanol solution with a mass concentration of 0.5-1.5%. The CeO2 ethanol solution was uniformly coated on the surface of the modified proton exchange membrane. The coated proton exchange membrane was dried and then heat-treated to obtain a fuel cell proton exchange membrane with high surface oxidation stability.

2. The method for improving the oxidative stability of the proton exchange membrane surface in a fuel cell according to claim 1, characterized in that, The MOF nanofibers described in S1-1 are hollow fibers with a length of 30–90 nm, an outer diameter of 8–15 nm, and an inner diameter of 5–10 nm.

3. The method for improving the oxidative stability of the proton exchange membrane surface in a fuel cell according to claim 1, characterized in that, The mixing method of MOF nanofibers and ammonium polyphosphate solution described in S1-1 is as follows: Ammonium polyphosphate is dissolved in deionized water according to the formula concentration ratio to obtain ammonium polyphosphate solution; then MOF nanofibers are added to the ammonium polyphosphate solution for stirring and impregnation, and an ultrasonic oscillator is used for stirring.

4. The method for improving the oxidative stability of the proton exchange membrane surface in a fuel cell according to claim 3, characterized in that, The stirring time is 1-3 hours, the stirring speed is 200-300 r / min, the ultrasonic oscillation frequency is 20-40 kHz, and the impregnation time is 5-20 hours.

5. The method for improving the oxidative stability of the proton exchange membrane surface in a fuel cell according to claim 1, characterized in that, The method for pretreatment of the proton exchange membrane described in S2 is as follows: the proton exchange membrane is soaked and cleaned with ethanol or acetone solution with a purity of 95-99% for 10-30 minutes, then soaked and cleaned with deionized water for 10-20 minutes, and then the surface is dried with nitrogen.

6. The method for improving the oxidative stability of a proton exchange membrane surface in a fuel cell according to claim 1, characterized in that, The CeO2 nanoparticles described in S3 were dispersed in an ethanol solution with a purity of 99–99.9% using an ultrasonic processor with a power of 200–300W for a dispersion time of 20–40 min.

7. The method for improving the oxidative stability of a proton exchange membrane surface in a fuel cell according to claim 1, characterized in that, The coating method described in S3 is as follows: the modified proton exchange membrane is placed on a spin coater, and CeO2 ethanol solution is sprayed onto the surface of the modified proton exchange membrane to ensure uniform contact between the membrane surface and the solution. The rotation speed of the spin coater is 500-1000 rpm, and the coating time is 20-30 s.

8. The method for improving the oxidative stability of a proton exchange membrane surface in a fuel cell according to claim 1, characterized in that, The drying method described in S3 is as follows: the coated proton exchange membrane is placed in an oven and dried at 80-120°C for 2-4 hours.

9. The method for improving the oxidative stability of a proton exchange membrane surface in a fuel cell according to claim 1, characterized in that, The heat treatment temperature of S3 is 200-400℃, and the heat treatment time is 1-2 hours.

10. The method for improving the oxidative stability of a proton exchange membrane surface in a fuel cell according to claim 1, characterized in that, The CeO2 nanoparticles described in S3 were dispersed in an ethanol solution with a purity of 99–99.9% using an ultrasonic processor with a power of 200–300W for a dispersion time of 20–40 min.

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