Aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane, its preparation method and application
The preparation method of perfluorosulfonic acid proton exchange membrane reinforced with aramid nanofibers solves the problems of insufficient mechanical strength and proton conductivity in the existing technology, and achieves high mechanical stability and high proton conductivity of the membrane, which is suitable for long-term application in fuel cells.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEBEI GELLEC NEW ENERGY MATERIAL SCI&TECHNOLOY CO LTD
- Filing Date
- 2023-08-11
- Publication Date
- 2026-05-26
AI Technical Summary
Existing perfluorosulfonic acid proton exchange membranes have shortcomings in terms of mechanical strength and proton conductivity. In particular, the mechanical strength decreases under repeated dry-wet alternation conditions, which affects the long-term application of fuel cells.
A method for preparing an aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane involves mixing aramid nanofibers with a perfluorosulfonic acid solution, stirring and allowing it to stand, then mixing it with a coagulant, coating it into a film, and performing post-treatment to form an aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane.
This improved the membrane's mechanical stability and proton conductivity, reduced water absorption and swelling, and enhanced the membrane's overall performance.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of battery technology, specifically relating to an aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane, its preparation method, and its application. Background Technology
[0002] The membrane electrode assembly (MEA), a core component of hydrogen fuel cells, mainly consists of three parts: the catalyst, the proton exchange membrane, and the gas diffusion layer. Currently, proton exchange membrane technology is monopolized by other countries. Domestically produced proton exchange membranes use perfluorosulfonic acid resin as their raw material, a key material in the chlor-alkali industry, hydrogen fuel cells, and water electrolysis for hydrogen production. However, its cost and performance also limit the commercial development of fuel cells. For the development of proton exchange membranes, "lower cost and higher performance" has always been the ultimate goal of researchers.
[0003] However, the existing methods for preparing proton exchange membranes and the resulting membranes still have shortcomings. The preparation process is complex, and the proton conductivity and tensile properties of the prepared membranes need further improvement. In particular, the swelling of homogeneous proton exchange membranes under repeated wet-dry cycles leads to a decrease in their mechanical strength and eventual failure. This is extremely detrimental to the long-term application of thin, homogeneous perfluorosulfonic acid proton exchange membranes in fuel cells.
[0004] Therefore, how to improve the proton conductivity of perfluorosulfonic acid proton exchange membranes while enhancing their mechanical strength has always been a research direction. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide an aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane.
[0006] Another object of the present invention is to provide a method for preparing the above-mentioned aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane.
[0007] The objective of this invention is achieved through the following technical solution.
[0008] A method for preparing an aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane includes the following steps:
[0009] Step 1: Mix aramid nanofibers, film-forming solvent, potassium tert-butoxide and methanol, and stir until the aramid nanofibers are uniformly dispersed to obtain an aramid nanofiber dispersion, wherein the concentration of aramid nanofibers in the aramid nanofiber dispersion is 1-5 wt%.
[0010] In step 1, the stirring speed is 30-300 r / min, the stirring temperature is 30-80℃, and the stirring time is 12-96 h.
[0011] In step 1, the aramid nanofibers are in the form of filaments.
[0012] In step 1, the ratio of the film-forming solvent, potassium tert-butoxide, and methanol, by mass parts, is (95-99):(0.1-0.5):(0.1-1.0).
[0013] Step 2: Mix the aramid nanofiber dispersion and the perfluorosulfonic acid (PFSA) solution, stir for at least 12 hours, and let stand until degassing to obtain the first mixed solution. The ratio of the perfluorosulfonic acid (PFSA) solution to the aramid nanofiber dispersion is (80-99):(1-20) by mass.
[0014] In step 2, the perfluorosulfonic acid (PFSA) solution is a mixture of perfluorosulfonic acid (PFSA) and a film-forming solvent.
[0015] In step 2, the ratio of the perfluorosulfonic acid (PFSA) solution to the aramid nanofiber dispersion is (88-99):(3-12), preferably (91-97):(3-9), by mass parts.
[0016] In step 2, the settling time is 1 to 3 hours.
[0017] Step 3: Mix the first mixed solution and the coagulant to obtain a second mixed solution. Pour the second mixed solution onto the substrate and coat it with a film to obtain a composite film.
[0018] In step 3, the coagulant is one or more of N-methylpyrrolidone, methanol, ethanol and water, and the coagulant accounts for 50 to 100% of the first mixed solution by mass.
[0019] Step 4: Let the composite membrane stand for 0.5-1 h, dry it, and finally anneal it at 100-150℃ for 1-3 h to obtain the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane precursor.
[0020] In step 4, the drying temperature is 60–100°C, and the drying time is 12–48 hours.
[0021] Step 5: Post-process the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane precursor to obtain the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane. The post-processing involves sequentially immersing the membrane in H2O2 aqueous solution, water, H2SO4 aqueous solution, and water.
[0022] In step 5, the post-treatment involves sequentially soaking the sample in an aqueous solution of H2O2 with a concentration of 5-10 wt%, water, an aqueous solution of H2SO4 with a concentration of 0.5-2 mol / L, and water for 0.5-2 hours respectively.
[0023] In step 5, the post-processing temperature is 60–100°C.
[0024] In the above technical solution, the method for preparing perfluorosulfonic acid solution includes: mixing perfluorosulfonic acid with a film-forming solvent under a nitrogen or inert gas environment and stirring, and then stirring for 4 to 8 hours until the perfluorosulfonic acid is uniformly dispersed in the film-forming solvent to obtain a perfluorosulfonic acid solution, wherein the concentration of perfluorosulfonic acid in the perfluorosulfonic acid solution is 5 to 10 wt%, and the stirring temperature is 100 to 200°C (preferably 120 to 140°C, and more preferably 125 to 135°C).
[0025] In the above technical solution, the stirring speed in the method for preparing perfluorosulfonic acid solution is 200-800 r / min.
[0026] In the above technical solution, the film-forming solvent is one or a mixture of several of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP).
[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0028] This invention introduces aramid nanofibers into the ion polymerization of perfluorosulfonic acid hydrocarbons to prepare aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membranes. The introduction of aramid nanofibers can not only improve the mechanical stability and ion exchange capacity of the aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane, but also improve the water absorption swelling rate and proton conductivity of the aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane. Detailed Implementation
[0029] The technical solution of the present invention will be further described below with reference to specific embodiments.
[0030] The raw materials and their manufacturers involved in the following examples are as follows:
[0031] Perfluorosulfonic acid (PFSA, powder): Shandong Dongyue Chemical Co., Ltd.;
[0032] Aramid nanofibers: Kevlar@49, industrial grade, DuPont, USA;
[0033] Potassium tert-butoxide: AR, Shanghai Aladdin Reagent Co., Ltd.;
[0034] Methanol, Ethanol: AR, Nanjing Chemical Reagent Co., Ltd.;
[0035] DMF: Analytical grade, Tianjin Aubokai Chemical Co., Ltd.;
[0036] The instruments and their model information involved in the following embodiments are as follows:
[0037] Thermostatic magnetic heating stirrer: HJ-4A; Jintan City Baitaxinbao Instrument Factory;
[0038] Drying oven: ZF-6020; Shanghai Jiecheng Experimental Instrument Co., Ltd.
[0039] The water used in the following examples is deionized water.
[0040] Proton conductivity testing method: The sample is fixed in the conductivity measurement cell and the bolts are tightened. Then, the conductivity testing device is placed in a constant temperature and humidity testing chamber. After the testing chamber reaches the set temperature (20℃) and relative humidity (100%) and stabilizes for 30 minutes, the conductivity is measured in a frequency range of 1Hz to 2×10⁻⁶. 6 The impedance spectrum of the sample was measured using an electrochemical impedance spectroscopy instrument under the conditions of Hz and a disturbance voltage of 10mV (see national standard GB / T 2004 2.3-2022).
[0041] For the test methods of water absorption swelling rate and ion exchange capacity, please refer to the national standard GB / T 20042.3-2022.
[0042] Examples 1-4
[0043] A method for preparing an aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane includes the following steps:
[0044] Step 1: Cut the filamentous aramid nanofibers into small pieces and mix them with the film-forming solvent, potassium tert-butoxide, and methanol. Stir slowly at 50°C for 48 hours at a speed of 150 r / min until the aramid nanofibers are uniformly dispersed to obtain an aramid nanofiber dispersion. The concentration of aramid nanofibers in the aramid nanofiber dispersion is 2 wt%. The film-forming solvent is N,N-dimethylformamide (DMF), and the ratio of film-forming solvent, potassium tert-butoxide, and methanol by mass is 98.8:0.236:0.94.
[0045] Step 2: Mix the aramid nanofiber dispersion and the perfluorosulfonic acid (PFSA) solution, stir for 12 hours, and let stand for 2 hours until degassing to obtain the first mixed solution. The ratio of the perfluorosulfonic acid (PFSA) solution to the aramid nanofiber dispersion is X by mass.
[0046] Step 3: Mix the first mixed solution and the coagulant (to exchange solvents) to obtain a second mixed solution. Pour the second mixed solution onto a clean and dry glass plate and coat it with a coater to obtain a composite film. The coagulant is ethanol, and by mass, the coagulant is 50% of the first mixed solution.
[0047] Step 4: First, let the composite membrane stand (air dry) for 30 minutes, then dry it in a vacuum environment at 80℃ for 12 hours, and finally anneal it at 120℃ for 1.5 hours to obtain the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane precursor.
[0048] Step 5: The aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane precursor is post-treated at 80℃ to obtain the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane. The post-treatment involves soaking the membrane in a 5wt% H2O2 aqueous solution, water, a 1mol / L H2SO4 aqueous solution, and water for 1 hour each.
[0049] In the above scheme, the method for preparing perfluorosulfonic acid solution includes: mixing perfluorosulfonic acid (powder) with a film-forming solvent under a nitrogen atmosphere and a rotation speed of Ar / min at B℃, and then stirring at B℃ for 4h until the perfluorosulfonic acid (powder) is uniformly dispersed in the film-forming solvent to obtain a perfluorosulfonic acid solution, wherein the concentration of perfluorosulfonic acid in the perfluorosulfonic acid solution is 5wt%, and the film-forming solvent is N,N-dimethylformamide (DMF).
[0050] Example X A B Example 1 97：3 500 120 Example 2 94：6 550 130 Example 3 91：9 600 140 Example 4 88：12 600 150
[0051] Comparative Example 1
[0052] A PFSA-based film includes the following steps:
[0053] S1. Pour N,N-dimethylformamide (DMF) into a dry and clean beaker, and add perfluorosulfonic acid (PFSA) powder while stirring at 500 r / min. Keep the temperature at 120℃ and continue stirring for 4 hours until the perfluorosulfonic acid (PFSA) powder is completely dissolved to obtain a perfluorosulfonic acid (PFSA) solution with a concentration of 5 wt%.
[0054] S2, the perfluorosulfonic acid (PFSA) solution obtained in S1 is placed in a vacuum oven at 50°C for degassing treatment;
[0055] S3: The perfluorosulfonic acid (PFSA) solution after degassing treatment in S2 is cast into a clean and dry membrane tank, dried in an oven at 80°C for 12 hours, and then annealed at 120°C for 1.5 hours to obtain a complete proton exchange membrane.
[0056] S4. The proton exchange membrane obtained in S3 was successively immersed in 5% H2O2 aqueous solution, deionized water, 1 mol / L H2SO4 aqueous solution and deionized water at 80℃ for 1 h each to obtain PFSA base membrane.
[0057] The parameters of the aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane prepared in the above embodiments and the PFSA-based membrane prepared in the comparative example are as follows:
[0058] Table 1
[0059]
[0060] Analysis of the data in Table 1 shows that, at 20℃, the proton conductivity of the aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membranes prepared in Examples 1-4 is 3.04 × 10⁻⁶. -2 ~7.88×10 -2 S.cm -1 The water absorption and swelling rate of the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membranes prepared in Examples 1-4 was measured to be 9.32%-13.44% at 20°C. In the mechanical property test, the tensile strength was between 14.65 and 21.47 MPa, indicating good mechanical properties.
[0061] Analysis of Comparative Example 1 and Example 1 shows that the proton conductivity and tensile strength of the aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane prepared in Example 1 are significantly higher than those of the PFSA base membrane prepared in Comparative Example 1, proving that the aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane formed by adding a small amount of aramid nanofibers has better performance.
[0062] Analysis of Examples 2 and 1 shows that the performance of the aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane prepared in Example 1 is not as good as that in Example 2, proving that increasing the content of aramid nanofibers results in a better composite proton exchange membrane. Analysis of Examples 2, 3, and 4 shows that the performance of the aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane prepared in Example 2 is better than that in Examples 3 and 4, proving that there is an optimal filling amount of aramid nanofibers, and the mechanical properties of the aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane are optimal.
[0063] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.
Claims
1. A method for preparing aramid nanofiber-reinforced perfluorosulfonic acid proton exchange membrane, characterized in that, Includes the following steps: Step 1: Mix aramid nanofibers, film-forming solvent, potassium tert-butoxide, and methanol, and stir until the aramid nanofibers are uniformly dispersed to obtain an aramid nanofiber dispersion. The concentration of aramid nanofibers in the dispersion is 1–5 wt%. Step 2: Mix the aramid nanofiber dispersion and the perfluorosulfonic acid solution, stir for at least 12 hours, and let stand until degassing to obtain the first mixed solution. The ratio of the perfluorosulfonic acid solution to the aramid nanofiber dispersion is (80-99):(1-20) by mass. Step 3: Mix the first mixed solution and the coagulant to obtain a second mixed solution. Pour the second mixed solution onto the substrate and coat it with a film to obtain a composite film. Step 4: Let the composite membrane stand for 0.5-1 h, dry it, and finally anneal it at 100-150℃ for 1-3 h to obtain the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane precursor. Step 5: Post-process the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane precursor to obtain the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane. The post-processing involves sequentially immersing the membrane in H2O2 aqueous solution, water, H2SO4 aqueous solution, and water.
2. The method for preparing the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane according to claim 1, characterized in that, The perfluorosulfonic acid solution is a mixture of perfluorosulfonic acid and a film-forming solvent. The perfluorosulfonic acid solution is prepared by the following method: under an inert gas environment and with stirring, perfluorosulfonic acid and a film-forming solvent are mixed and stirred for 4 to 8 hours until the perfluorosulfonic acid is uniformly dispersed in the film-forming solvent to obtain a perfluorosulfonic acid solution. The concentration of perfluorosulfonic acid in the perfluorosulfonic acid solution is 5 to 10 wt%, and the stirring temperature is 100 to 200°C.
3. The method for preparing the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane according to claim 1, characterized in that, In step 1, the ratio of the film-forming solvent, potassium tert-butoxide, and methanol, by mass parts, is (95-99):(0.1-0.5):(0.1-1.0).
4. The method for preparing the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane according to claim 1, 2, or 3, characterized in that, The film-forming solvent is one or a mixture of several of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone.
5. The method for preparing the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane according to claim 1, characterized in that, In step 3, the coagulant is one or more of N-methylpyrrolidone, methanol, ethanol and water, and the coagulant accounts for 50 to 100% of the first mixed solution by mass.
6. The method for preparing the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane according to claim 1, characterized in that, In step 5, the post-treatment involves sequentially soaking the sample in an aqueous solution of H2O2 with a concentration of 5-10 wt%, water, an aqueous solution of H2SO4 with a concentration of 0.5-2 mol / L, and water for 0.5-2 hours each, with the post-treatment temperature being 60-100℃.
7. The method for preparing the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane according to claim 1, characterized in that, In step 1, the stirring speed is 30-300 r / min, the stirring temperature is 30-80℃, and the stirring time is 12-96 h.
8. The method for preparing the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane according to claim 1, characterized in that, In step 2, the settling time is 1 to 3 hours. In step 4, the drying temperature is 60 to 100°C and the drying time is 12 to 48 hours.
9. The method for preparing the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane according to claim 1, characterized in that, In step 2, the ratio of the perfluorosulfonic acid solution to the aramid nanofiber dispersion is (88-99):(3-12) by mass.
10. The method for preparing the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane according to claim 2, characterized in that, In the method for preparing perfluorosulfonic acid solution, the stirring speed is 200-800 r / min, and the stirring temperature is 120-140℃.
11. The method for preparing the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane according to claim 9, characterized in that, In step 2, the ratio of the perfluorosulfonic acid solution to the aramid nanofiber dispersion is (91-97):(3-9) by mass.
12. The method for preparing the aramid nanofiber reinforced perfluorosulfonic acid proton exchange membrane according to claim 10, characterized in that, In the method for preparing perfluorosulfonic acid solution, the stirring speed is 200-800 r / min, and the stirring temperature is 125-135℃.