Ppta / pfsa blended proton exchange membrane, and preparation method and application thereof

Abstract

This invention discloses a PPTA / PFSA blend proton exchange membrane, its preparation method, and its application. The preparation method of the PPTA / PFSA blend proton exchange membrane includes the following steps: Under a nitrogen or inert gas environment and with stirring, perfluorosulfonic acid is added in batches to a first membrane-forming solvent and stirred until homogeneous. Then, a co-solubilizing salt is added and stirred until homogeneous to obtain solution B. p-phenylenediamine is added to solution B at 10–15°C and stirred until homogeneous to obtain solution C. A terephthaloyl chloride solution is poured into solution C at -10–0°C to undergo a low-temperature reaction, resulting in solution D. Polyvinylpyrrolidone is added and stirred until homogeneous to obtain a casting solution, wherein terephthaloyl chloride is dissolved in a second membrane-forming solvent to form a terephthaloyl chloride solution. After degassing the casting solution, it is poured onto a substrate, coated, exposed to air for at least 10 seconds, and then immersed in water for phase inversion to form a membrane, thus obtaining a PPTA / PFSA blend proton exchange membrane on the substrate. The preparation method of this invention can simultaneously improve the mechanical strength and proton conductivity of the proton exchange membrane.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a PPTA / PFSA blend proton exchange membrane, its preparation method, and its application. Background Technology

[0002] The proton exchange membrane (PEM) is a core component of fuel cells, and its cost and performance limit its commercialization. For PEM development, "lower cost and higher performance" has always been the ultimate goal for researchers. The introduction of nanofiber structures can significantly improve the overall performance of PEMs. While perfluorosulfonic acid (Nafion) membranes possess good overall performance, their high cost necessitates the addition of other polymer materials to reduce the Nafion content and utilize fiber structures to improve performance.

[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 a PPTA / PFSA blend proton exchange membrane.

[0006] Another objective of this invention is to provide a method for preparing a PPTA / PFSA blend proton exchange membrane.

[0007] The present invention is achieved through the following technical solution.

[0008] A PPTA / PFSA blend proton exchange membrane is prepared from p-phenylenediamine (PPD), terephthaloyl chloride (TPC), perfluorosulfonic acid (PFSA), polyvinylpyrrolidone (PVP), a membrane-forming solvent, and a co-solubilizing salt. The ratio of p-phenylenediamine (PPD), terephthaloyl chloride (TPC), perfluorosulfonic acid (PFSA), polyvinylpyrrolidone (PVP), and co-solubilizing salt, by mass parts, is (0.1-0.8):(0.1-1):(15-20):2:(0.01-0.2).

[0009] In the above technical solution, the co-solubilizing salt is one or a mixture of calcium chloride, lithium chloride and magnesium chloride.

[0010] In the above technical solution, the film-forming solvent is N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), or N-methylpyrrolidone (NMP).

[0011] In the above technical solution, the ratio of p-phenylenediamine (PPD), terephthaloyl chloride (TPC), perfluorosulfonic acid (PFSA), polyvinylpyrrolidone (PVP) and solubilizing salt by mass parts is (0.1-0.8):(0.7-1):(15-18):2:(0.01-0.15).

[0012] In the above technical solution, the ratio of the film-forming solvent to terephthaloyl chloride is 80:(0.1~1) by mass parts.

[0013] The preparation method of the above-mentioned PPTA / PFSA blend proton exchange membrane includes the following steps:

[0014] S1, Under a nitrogen or inert gas environment and with stirring, perfluorosulfonic acid is added in batches to the first film-forming solvent while maintaining the nitrogen or inert gas environment and stirring until the perfluorosulfonic acid is uniformly dispersed in the first film-forming solvent to obtain solution A;

[0015] In S1, the stirring speed for stirring until the perfluorosulfonic acid is uniformly dispersed in the first film-forming solvent is 200-800 r / min, the stirring time is 4-6 h, and the stirring temperature is 100-200 °C.

[0016] In S1, the mass of perfluorosulfonic acid added in each batch is no more than 2g.

[0017] S2, add the co-solubilizing salt to the solution A and stir until the co-solubilizing salt is evenly dispersed in the solution A to obtain solution B;

[0018] In S2, the stirring speed is 200-800 r / min, the stirring time is 0.5-2 h, and the stirring temperature is 60-100℃.

[0019] S3, add p-phenylenediamine to solution B at 10-15℃, and stir until p-phenylenediamine is evenly dispersed in solution B to obtain solution C;

[0020] In S3, the stirring speed is 200-800 r / min, the stirring time is 0.5-2 h, and the stirring temperature is 10-15℃.

[0021] S4, terephthaloyl chloride solution is poured into solution C at -10 to 0°C to undergo a low-temperature reaction, resulting in solution D. Polyvinylpyrrolidone is mixed with solution D and stirred at 50 to 80°C to obtain a casting solution. The method for obtaining the terephthaloyl chloride solution is as follows: the terephthaloyl chloride is dissolved in a second film-forming solvent to form a terephthaloyl chloride solution, wherein the film-forming solvent is composed of a first film-forming solvent and a second film-forming solvent.

[0022] In S4, the low-temperature reaction time is 0.5 to 1 hour.

[0023] In S4, the stirring speed is 200-800 r / min, and the stirring time is 0.5-2 h.

[0024] In S4, the ratio of the first film-forming solvent to the second film-forming solvent by volume is (1-10):1.

[0025] S5. After degassing the casting solution, pour it onto the substrate, coat it with a scraper, expose it to air for at least 10 seconds, and then immerse it in water to undergo phase inversion and form a film, thus obtaining a PPTA / PFSA blend proton exchange membrane on the substrate.

[0026] In S5, the degassing treatment involves placing the container at 20–50°C for 0.5–1 hour.

[0027] The use of PPTA in simultaneously improving the mechanical strength and proton conductivity of PFSA proton exchange membranes.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This invention produces PPTA by polycondensation of p-phenylenediamine (PPD) and terephthaloyl (TPC) under low-temperature solution conditions. By combining PPTA with PFSA, the mechanical strength and proton conductivity (proton electrical conductivity) of the proton exchange membrane are improved simultaneously. Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0031] The raw materials and manufacturers involved in this invention are as follows:

[0032] Perfluorosulfonic acid powder (PFSA): Shandong Dongyue Chemical Co., Ltd.;

[0033] PPD: 99%; Sigma-Aldrich Trading Co., Ltd.;

[0034] TPC: 99%; Sigma-Aldrich Trading Ltd.

[0035] LiCl: Analytical grade; Tianjin Aubokai Chemical Co., Ltd.

[0036] PVP: Analytical grade; Tianjin Guangfu Chemical Reagent Co., Ltd.

[0037] NMP: Analytical grade; Tianjin Aubokai Chemical Co., Ltd.

[0038] The equipment and model information involved in this invention are as follows:

[0039] Thermostatic magnetic heating stirrer: HJ-4A; Jintan City Baitaxinbao Instrument Factory;

[0040] Drying oven: ZF-6020; Shanghai Jiecheng Experimental Instrument Co., Ltd.

[0041] This invention relates to PPTA, synthesized by the condensation polymerization of monomers p-phenylenediamine (PPD) and terephthaloyl (TPC) under low-temperature solution conditions. Over 85% of its internal amide functional groups are directly bonded to the benzene ring, forming a high-density hydrogen bond network. Microscopically, the molecular chains are rod-shaped, and after orientation, the chains are tightly packed together through hydrogen bonding. Macroscopically, PPTA exhibits high strength and high modulus, with a strength four times that of ordinary steel bars. It also possesses excellent heat resistance, mechanical properties, and solvent resistance. Combining PPTA with PFSA further enhances the proton conductivity of proton exchange membranes while increasing mechanical strength.

[0042] The chemical structure of para-aramid (PPTA) is shown below:

[0043]

[0044] Examples 1-4

[0045] A PPTA / PFSA blend proton exchange membrane is prepared from p-phenylenediamine (PPD), terephthaloyl chloride (TPC), perfluorosulfonic acid (PFSA), polyvinylpyrrolidone (PVP), a membrane-forming solvent, and a co-solvent. The ratio of the membrane-forming solvent, p-phenylenediamine, terephthaloyl chloride, perfluorosulfonic acid, polyvinylpyrrolidone, and co-solvent, by mass parts, is X, as shown in Table 1. In this embodiment, the co-solvent is lithium chloride, and the membrane-forming solvent is N-methylpyrrolidone (NMP).

[0046] The film-forming solvent is divided into a first film-forming solvent and a second film-forming solvent. By volume, the ratio of the first film-forming solvent to the second film-forming solvent is 60:20.

[0047] A method for preparing a PPTA / PFSA blend proton exchange membrane, comprising the following steps:

[0048] S1. Under an argon (Ar) atmosphere and with stirring, perfluorosulfonic acid is added in batches to a beaker containing the first film-forming solvent. The mass of each batch of perfluorosulfonic acid added is no more than 2g. The argon (Ar) atmosphere is maintained, and the mixture is stirred at 400r / min for 4h at a temperature of T℃ until the perfluorosulfonic acid is uniformly dispersed in the first film-forming solvent to obtain solution A.

[0049] S2, add the co-solubilizing salt to solution A, and stir at 80℃ and 650 r / min for 1 h until the co-solubilizing salt is evenly dispersed in solution A to obtain solution B;

[0050] S3, cool solution B to 15°C in a water bath, add p-phenylenediamine to solution B at 15°C, and stir at 600 r / min for 40 min at 15°C to uniformly disperse p-phenylenediamine in solution B, thus obtaining solution C.

[0051] S4, cool solution C to 0°C in a water bath for 30 min, pour terephthaloyl chloride solution into solution C at 0°C, and allow it to react at low temperature for 30 min to obtain solution D. Mix polyvinylpyrrolidone with solution D and stir at 400 r / min for 1 h at 60°C to obtain casting solution. In this embodiment, the method for obtaining terephthaloyl chloride solution is as follows: dissolve terephthaloyl chloride in a second film-forming solvent to form terephthaloyl chloride solution.

[0052] S5. After degassing the casting solution, pour it onto a clean and dry glass plate, coat it with a coating tool, expose it to air for 10 seconds, and then immerse it in deionized water to form a phase inversion membrane. A PPTA / PFSA blend proton exchange membrane is obtained on the substrate. The degassing treatment is performed by placing it in a vacuum oven at 50°C for 30 minutes.

[0053] Table 1

[0054]

[0055]

[0056] Comparative Example 1

[0057] A PFSA-based membrane is prepared from perfluorosulfonic acid (PFSA), polyvinylpyrrolidone (PVP) and a film-forming solvent, wherein the ratio of film-forming solvent, perfluorosulfonic acid and polyvinylpyrrolidone by mass is 60:18:2, and the film-forming solvent is N-methylpyrrolidone (NMP).

[0058] A method for preparing a PFSA-based film, comprising the following steps:

[0059] S1. Under an argon atmosphere and with stirring, perfluorosulfonic acid is added in batches to a beaker containing a film-forming solvent. The mass of each batch of perfluorosulfonic acid added is no more than 2g. The argon atmosphere is maintained, and the mixture is stirred at 400r / min for 4h at 110℃ until the perfluorosulfonic acid is uniformly dispersed in the film-forming solvent to obtain solution A.

[0060] S2, cool solution A to 60°C in a water bath, mix polyvinylpyrrolidone with solution A, and stir at 350 r / min for 1 h at 60°C to obtain casting solution;

[0061] S3. After degassing the casting solution, it is poured into a clean and dry film tank, placed in an oven and dried at 80°C for 12 hours, and then annealed at 120°C for 1.5 hours to obtain the PFSA base film. The degassing treatment is performed by placing the film in a vacuum oven at 50°C for 30 minutes.

[0062] The performance parameter test data of the PPTA / PFSA blend proton exchange membrane or PFSA base membrane described in the above embodiments and comparative examples are shown in Table 2.

[0063] Table 2

[0064]

[0065]

[0066] Analysis of Table 2 shows that the PPTA / PFSA blend proton exchange membranes and PFSA base membranes from the examples and comparative examples were soaked in 5wt% H2O2 aqueous solution, deionized water, 1mol / L H2SO4 aqueous solution, and deionized water, respectively, at 80℃ for 1 hour each. At 20℃, the proton conductivity of the PPTA / PFSA blend proton exchange membranes obtained in Examples 1-4 was 5.89 × 10⁻⁶. -2 -7.02×10 -2 S.cm -1 The water absorption and swelling rate was measured to be 8.71%-11.27% at 20℃. In the mechanical property test, the tensile strength in the transverse direction was between 19.7-27.4 MPa, and the tensile strength in the longitudinal direction was between 19.2-29.5 MPa, indicating good mechanical properties.

[0067] Analysis of Comparative Example 1 and Example 1 shows that the proton conductivity and tensile strength of the PPTA / PFSA blend proton exchange membrane in Example 1 are significantly higher than those in Comparative Example 1, proving that the PPTA / PFSA blend proton exchange membrane formed by adding PPTA has better performance.

[0068] Analysis of Example 2 and Example 1 shows that the performance of Example 1 is not as good as that of Example 2, proving that increasing the content of the synthesized PPTA monomer results in a better composite proton exchange membrane.

[0069] Analysis of Examples 3 and 4 shows that Example 4 performs better than Example 3, proving that increasing the PFSA dissolution temperature can significantly improve the tensile strength of the composite proton exchange membrane.

Claims

1. A method for preparing a PPTA / PFSA blend proton exchange membrane, characterized in that, The PPTA / PFSA blend proton exchange membrane is prepared from p-phenylenediamine, terephthaloyl chloride, perfluorosulfonic acid, polyvinylpyrrolidone, membrane-forming solvent, and co-solvent, wherein, by mass parts, the ratio of p-phenylenediamine, terephthaloyl chloride, perfluorosulfonic acid, polyvinylpyrrolidone, and co-solvent is (0.1~0.8):(0.1~1):(15~20):2:(0.01~0.2). The preparation method of the PPTA / PFSA blend proton exchange membrane includes the following steps: S1, Under a nitrogen or inert gas environment and with stirring, perfluorosulfonic acid is added in batches to the first film-forming solvent while maintaining the nitrogen or inert gas environment and stirring until the perfluorosulfonic acid is uniformly dispersed in the first film-forming solvent to obtain solution A; S2, add the co-solubilizing salt to the solution A and stir until the co-solubilizing salt is evenly dispersed in the solution A to obtain solution B; S3, add p-phenylenediamine to solution B at 10~15℃, stir until p-phenylenediamine is evenly dispersed in solution B, to obtain solution C; S4, terephthaloyl chloride solution is poured into solution C at -10~0℃ to undergo a low-temperature reaction, resulting in solution D. Polyvinylpyrrolidone is mixed with solution D and stirred at 50~80℃ to obtain a casting solution. The method for obtaining the terephthaloyl chloride solution is as follows: the terephthaloyl chloride is dissolved in a second film-forming solvent to form a terephthaloyl chloride solution, wherein the film-forming solvent is composed of a first film-forming solvent and a second film-forming solvent. S5. After degassing the casting solution, pour it onto the substrate, coat it with a scraper, expose it to air for at least 10 seconds, and then immerse it in water to undergo phase inversion and form a film, thus obtaining a PPTA / PFSA blend proton exchange membrane on the substrate.

2. The preparation method according to claim 1, characterized in that, The co-solubilizing salt is one or a mixture of calcium chloride, lithium chloride, and magnesium chloride.

3. The preparation method according to claim 2, characterized in that, The film-forming solvent is N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone.

4. The preparation method according to claim 1, characterized in that, The ratio of p-phenylenediamine, terephthaloyl chloride, perfluorosulfonic acid, polyvinylpyrrolidone and co-solubilizing salt by mass parts is (0.1~0.8):(0.7~1):(15~18):2:(0.01~0.15).

5. The preparation method according to claim 1, characterized in that, The ratio of the film-forming solvent to terephthaloyl chloride is 80:(0.1~1) by mass.

6. The preparation method according to claim 1, characterized in that, In S4, the low-temperature reaction time is 0.5~1h.

7. The preparation method according to claim 1, characterized in that, In S1, the mass of perfluorosulfonic acid added in each batch is no more than 2g.

8. The preparation method according to claim 1, characterized in that, In S4, the ratio of the first film-forming solvent to the second film-forming solvent by volume is (1~10):

1.

9. The preparation method according to claim 1, characterized in that, In S1, the stirring speed is 200~800 r / min, the stirring time is 4~6 h, and the stirring temperature is 100~200℃, until the perfluorosulfonic acid is uniformly dispersed in the first film-forming solvent.

10. The preparation method according to claim 1, characterized in that, In S2, the stirring speed is 200~800 r / min, the stirring time is 0.5~2 h, and the stirring temperature is 60~100℃.

11. The preparation method according to claim 1, characterized in that, In S3, the stirring speed is 200~800 r / min, the stirring time is 0.5~2 h, and the stirring temperature is 10~15℃.

12. The preparation method according to claim 1, characterized in that, In S4, the stirring speed is 200~800 r / min, and the stirring time is 0.5~2 h.

13. The preparation method according to claim 1, characterized in that, In S5, the degassing treatment involves placing the container at 20-50°C for 0.5-1 hour.

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