A proton membrane with a tetrafluoroethylene membrane as the skeleton and a preparation method thereof

Abstract

The present invention relates to the technical field of proton membranes, and particularly to a proton membrane with a tetrafluoroethylene membrane as a skeleton and a preparation method thereof. The proton membrane is composed of a tetrafluoroethylene membrane as a skeleton and a mixed coating coated on both sides. The mixed coating is prepared from the following raw materials in parts by weight: 30-35 wt% of perfluorosulfonic acid solution, 2-4 wt% of modified silica, and the balance being a high-boiling solvent. Through the fixing effect of the polytetrafluoroethylene membrane, the modified silica exists in the proton exchange membrane in the present invention, ensuring the durability of the proton exchange membrane during the operation of the battery; among them, the effects of different silane coupling agents on silica are different, and the silica modified by triaminosilane coupling agent has the best effect on improving the durability of the proton exchange membrane.

Description

Technical Field

[0001] The present invention relates to the technical field of proton membranes, and particularly to a proton membrane with a tetrafluoroethylene membrane as the backbone and a preparation method thereof. Background Art

[0002] A hydrogen fuel cell is an energy conversion device that can continuously convert the chemical energy stored in hydrogen into electrical energy. It has the advantages of being green and environmentally friendly, having a high energy conversion efficiency, and low noise, and is considered the fourth-generation power generation technology after hydropower, thermal power, and nuclear power. Fuel cells can be used in passenger cars, airplanes, ships, portable power supplies, aerospace, and stationary power plants. Except for stationary power plants, most fuel cell application sites are sensitive to the volume of the fuel cell system. Therefore, improving the power density of fuel cells has become the current development trend of fuel cell systems. Reducing the thickness of the proton exchange membrane can significantly reduce the internal resistance of the fuel cell and improve the power density of the fuel cell. However, the proton exchange membrane is vulnerable to chemical corrosion from free radicals, which can then form pinholes or cracks. When the pinholes or cracks penetrate each other, it will increase the hydrogen permeation amount, reduce the performance of the fuel cell, and even cause accidents. Moreover, these problems are particularly significant in thinner proton exchange membranes. A radical quencher is a substance that sacrifices itself to react with active free radicals, which can reduce the chemical corrosion suffered by the proton exchange membrane, thereby improving the durability of the proton exchange membrane.

[0003] Radical quenchers include metal oxides, natural phenolic substances, and organic compounds such as nitrogen-containing heterocyclic compounds. Since the radical quenching activity of organic radical quenchers is much lower than that of metal oxides, metal oxide radical quenchers are generally incorporated into existing high-durability proton exchange membranes, and such metal oxides are generally single-metal oxides. The radical quenching activity of metal oxides comes from the surface defect states. However, metal oxides have good crystallinity and the surface defect state concentration is generally low, resulting in a low actual surface utilization rate of metal oxides. In addition, the surface of a single-component metal oxide is prone to dissolution in an acidic environment, generating free metal ions. When the metal ions coordinate with some groups in the perfluorosulfonic acid resin, it will cause a decrease in proton conduction ability. Moreover, when the proton exchange membrane is assembled into a fuel cell single cell, the dissolved metal ions will gradually accumulate in the cathode and anode catalyst layers, causing serious attenuation of the single cell performance.

[0004] Based on the above situation, the present invention proposes a proton membrane with a tetrafluoroethylene membrane as the backbone and a preparation method thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a proton membrane with a tetrafluoroethylene membrane as the backbone and a preparation method thereof.

[0006] To achieve the above object, the present invention provides a proton membrane with a tetrafluoroethylene membrane as the skeleton. The proton membrane is composed of a tetrafluoroethylene membrane as the skeleton and a mixed coating coated on both sides. The mixed coating is prepared from the following raw materials in parts by weight: 30-35 wt% of perfluorosulfonic acid solution, 2-4 wt% of modified silica, and the balance is a high-boiling solvent.

[0007] Preferably, the thickness of the tetrafluoroethylene membrane is 10-20 μm, the porosity is ≥80%, and the pore diameter is 0.3-0.5 μm.

[0008] Preferably, the perfluorosulfonic acid solution is composed of the following raw materials in weight percentages: 15-20 wt% of perfluorosulfonic acid resin, 80-85 wt% of low-boiling alcohol solution.

[0009] Preferably, the low-boiling alcohol solution is anhydrous isopropanol.

[0010] Preferably, the high-boiling solvent is one of a high-boiling non-alcohol solution or a high-boiling alcohol solution.

[0011] Preferably, the high-boiling solvent is a high-boiling non-alcohol solution, including one of N-N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, N-N-dimethylacetamide.

[0012] Preferably, the modified silica is prepared by the following method:

[0013] (1) The fumed silica is refluxed in an ethanol solution of dilute hydrochloric acid (V HCL :V 乙醇 = 1:20) at 85-90 °C for 55-60 h, and centrifuged at 8000-9000 r / min for 5-10 min to obtain mesoporous silica particles;

[0014] (2) The mesoporous silica particles and the amino silane coupling agent are mixed in a weight ratio of 1:0.05 and stirred at 180-200 rpm for 18-20 h, and centrifuged at 8000-9000 r / min for 5-10 min to obtain modified silica.

[0015] Preferably, the amino silane coupling agent includes one of a monoamino silane coupling agent, a diamino silane coupling agent, and a triamino silane coupling agent.

[0016] Preferably, the amino silane coupling agent is a triamino silane coupling agent, and the triamino silane coupling agent is N-(piperazinylethyl)-3-aminopropylmethyldimethoxysilane, with a cas number of 128644-51-9.

[0017] The molecular structure of N-(piperazinylethyl)-3-aminopropylmethyldimethoxysilane contains a secondary amino group, a piperazinyl group (with two tertiary amino groups) as functional groups, and two hydrolyzable methoxy groups. This dual reactivity allows it to enhance the bonding, adhesion, and compatibility between inorganic materials and organic polymers through bidirectional chemical reactions, thereby improving the performance of the overall composite material.

[0018] The present invention also provides a method for preparing a proton membrane with a tetrafluoroethylene membrane as the backbone, and the method comprises the following steps:

[0019] (1) Take anhydrous isopropanol and perfluorosulfonic acid resin, heat and dissolve them in a reaction kettle at 1.5 ± 0.2 Mpa for 5 - 6 h to obtain a perfluorosulfonic acid solution;

[0020] (2) Take the perfluorosulfonic acid solution and a high-boiling solvent, mix and stir them at 300 - 400 rpm for 10 - 15 min to obtain a mixed solution;

[0021] (3) Subsequently, add modified silica to the mixture in step (2), mix and stir it at 300 - 400 rpm for 10 - 15 min, and then ultrasonically treat it at an ultrasonic power of 500 - 600 w and a temperature of 40 - 45 °C for 50 - 60 min to obtain a mixed coating solution;

[0022] (4) Take anhydrous isopropanol to infiltrate the tetrafluoroethylene membrane to make it transparent, uniformly coat the two sides of the tetrafluoroethylene membrane with the mixed coating solution in step (3), perform heat treatment at 140 - 150 °C for 60 - 70 min, and then cure it at 160 - 175 °C for 1 - 2 h to obtain the product.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Through the fixing effect of the polytetrafluoroethylene membrane in the present invention, the modified silica exists in the proton exchange membrane, ensuring the durability of the proton exchange membrane during the operation of the battery; among them, different silane coupling agents have different effects on silica, and the silica modified with triaminosilane coupling agent has the best effect on improving the durability of the proton exchange membrane.

[0025] 2. The preparation method of the present invention is convenient to operate, easy to scale up production, and has stable quality.

[0026] 3. The raw materials of the present invention are abundant in China and have appropriate prices, making the large-scale production not restricted by too high costs. Detailed implementation mode

[0027] Preparation of Modified Silicon Dioxide in Example 1

[0028] (1) Put the fumed silica in an ethanol solution of dilute hydrochloric acid (VHCL : V 乙醇 = 1:20) was refluxed at 90 °C for 55 h and centrifuged at 8000 r / min for 10 min to obtain mesoporous silica particles;

[0029] (2) The mesoporous silica particles and the amino-silane coupling agent were mixed at a weight ratio of 1:0.05 and stirred at 180 rpm for 20 h, then centrifuged at 9000 r / min for 5 min to obtain modified silica.

[0030] Example 2

[0031] The dosages of each raw material are shown in Table 1.

[0032] (1) Take anhydrous isopropanol and perfluorosulfonic acid resin, heat and dissolve them in a reaction kettle at 1.5 ± 0.2 Mpa for 5 h to obtain a perfluorosulfonic acid solution;

[0033] (2) Take the perfluorosulfonic acid solution and the high-boiling solvent, mix and stir them at 300 rpm for 15 min to obtain a mixed solution;

[0034] (3) Then add the modified silica to the mixture in step (2), mix and stir it at 300 rpm for 15 min, and then ultrasonically irradiate it at a ultrasonic power of 500 w and a temperature of 40 °C for 60 min to obtain a mixed coating solution;

[0035] (4) Take anhydrous isopropanol to infiltrate the polytetrafluoroethylene membrane to make it transparent, uniformly coat the mixed coating solution in step (3) on both sides of the polytetrafluoroethylene membrane, heat-treat it at 140 °C for 70 min, and then cure it at 160 °C for 2 h to obtain the product.

[0036] Example 3

[0037] The dosages of each raw material are shown in Table 1.

[0038] (1) Take anhydrous isopropanol and perfluorosulfonic acid resin, heat and dissolve them in a reaction kettle at 1.5 ± 0.2 Mpa for 6 h to obtain a perfluorosulfonic acid solution;

[0039] (2) Take the perfluorosulfonic acid solution and the high-boiling solvent, mix and stir them at 400 rpm for 10 min to obtain a mixed solution;

[0040] (3) Then add the modified silica to the mixture in step (2), mix and stir it at 400 rpm for 10 min, and then ultrasonically irradiate it at a ultrasonic power of 600 w and a temperature of 45 °C for 50 min to obtain a mixed coating solution;

[0041] (4) Take anhydrous isopropanol to infiltrate the polytetrafluoroethylene membrane to make it transparent, evenly coat the mixed coating solution in step (3) on both sides of the polytetrafluoroethylene membrane, heat-treat at 150 °C for 60 min, and then cure at 175 °C for 1 h to obtain it.

[0042] Example 4

[0043] The dosages of each raw material are shown in Table 1.

[0044] (1) Take anhydrous isopropanol and perfluorosulfonic acid resin, heat and dissolve in a reaction kettle at 1.5 ± 0.2 Mpa for 6 h to obtain a perfluorosulfonic acid solution;

[0045] (2) Take the perfluorosulfonic acid solution and a high-boiling solvent, mix and stir at 400 rpm for 15 min to obtain a mixed solution;

[0046] (3) Then add modified silica to the mixture in step (2), mix and stir at 400 rpm for 15 min, and then ultrasonically irradiate at an ultrasonic power of 600 w and a temperature of 45 °C for 60 min to obtain a mixed coating solution;

[0047] (4) Take anhydrous isopropanol to infiltrate the polytetrafluoroethylene membrane to make it transparent, evenly coat the mixed coating solution in step (3) on both sides of the polytetrafluoroethylene membrane, heat-treat at 150 °C for 70 min, and then cure at 175 °C for 2 h to obtain it.

[0048] Comparative Example 1

[0049] The difference from Example 4 is that the silane coupling agent used is a monoamino silane coupling agent with a CAS number of 13822 - 56 - 5. The dosages of each raw material are shown in Table 1. The specific steps are as follows:

[0050] (1) Take anhydrous isopropanol and perfluorosulfonic acid resin, heat and dissolve in a reaction kettle at 1.5 ± 0.2 Mpa for 6 h to obtain a perfluorosulfonic acid solution;

[0051] (2) Take the perfluorosulfonic acid solution and a high-boiling solvent, mix and stir at 400 rpm for 15 min to obtain a mixed solution;

[0052] (3) Then add modified silica to the mixture in step (2), mix and stir at 400 rpm for 15 min, and then ultrasonically irradiate at an ultrasonic power of 600 w and a temperature of 45 °C for 60 min to obtain a mixed coating solution;

[0053] (4) Take anhydrous isopropanol to infiltrate the polytetrafluoroethylene membrane to make it transparent, evenly coat the mixed coating solution in step (3) on both sides of the polytetrafluoroethylene membrane, heat-treat at 150 °C for 70 min, and then cure at 175 °C for 2 h to obtain it.

[0054] Comparative Example 2

[0055] Different from Example 4, the silane coupling agent used is a diamino silane coupling agent with a CAS number of 1760-24-3. The dosages of each raw material are shown in Table 1. The specific steps are as follows:

[0056] (1) Take anhydrous isopropanol and perfluorosulfonic acid resin, and heat and dissolve them in a reaction kettle at 1.5 ± 0.2 Mpa for 6 h to obtain a perfluorosulfonic acid solution;

[0057] (2) Take the perfluorosulfonic acid solution and a high-boiling solvent, and mix and stir them at 400 rpm for 15 min to obtain a mixed solution;

[0058] (3) Then add modified silica to the mixture in step (2), mix and stir it at 400 rpm for 15 min, and then ultrasonicate it at an ultrasonic power of 600 w and a temperature of 45 °C for 60 min to obtain a mixed coating solution;

[0059] (4) Take anhydrous isopropanol to infiltrate the polytetrafluoroethylene membrane to make it transparent, evenly coat the double sides of the polytetrafluoroethylene membrane with the mixed coating solution in step (3), heat-treat it at 150 °C for 70 min, and then cure it at 175 °C for 2 h to obtain it.

[0060] Comparative Example 3

[0061] Different from Example 4, the silane coupling agent used is another amino silane coupling agent with a CAS number of 99740-64-4. The dosages of each raw material are shown in Table 1. The specific steps are as follows:

[0062] (1) Take anhydrous isopropanol and perfluorosulfonic acid resin, and heat and dissolve them in a reaction kettle at 1.5 ± 0.2 Mpa for 6 h to obtain a perfluorosulfonic acid solution;

[0063] (2) Take the perfluorosulfonic acid solution and a high-boiling solvent, and mix and stir them at 400 rpm for 15 min to obtain a mixed solution;

[0064] (3) Then add modified silica to the mixture in step (2), mix and stir it at 400 rpm for 15 min, and then ultrasonicate it at an ultrasonic power of 600 w and a temperature of 45 °C for 60 min to obtain a mixed coating solution;

[0065] (4) Take anhydrous isopropanol to infiltrate the polytetrafluoroethylene membrane to make it transparent, evenly coat the double sides of the polytetrafluoroethylene membrane with the mixed coating solution in step (3), heat-treat it at 150 °C for 70 min, and then cure it at 175 °C for 2 h to obtain it.

[0066] Comparative Example 4

[0067] Different from Example 4, the high-boiling solvent used is a high-boiling alcohol solution, namely 1,2-propanediol solution. The dosages of each raw material are shown in Table 1. The specific steps are as follows:

[0068] (1) Take anhydrous isopropanol and perfluorosulfonic acid resin, and heat and dissolve them in a reaction kettle at 1.5 ± 0.2 Mpa for 6 h to obtain a perfluorosulfonic acid solution;

[0069] (2) Take the perfluorosulfonic acid solution and the high-boiling alcohol solution, and mix and stir them at 400 rpm for 15 min to obtain a mixed solution;

[0070] (3) Then add modified silica to the mixture in step (2), mix and stir it at 400 rpm for 15 min, and then ultrasonically treat it at an ultrasonic power of 600 w and a temperature of 45 °C for 60 min to obtain a mixed coating solution;

[0071] (4) Take anhydrous isopropanol to infiltrate the polytetrafluoroethylene membrane to make it transparent, evenly coat the mixed coating solution in step (3) on both sides of the polytetrafluoroethylene membrane, heat-treat it at 150 °C for 70 min, and then cure it at 175 °C for 2 h to obtain it.

[0072] Table 1

[0073]

[0074] Performance Testing and Evaluation

[0075] The proton exchange membranes prepared in Examples 2 to 4 and Comparative Examples 1 to 4 were tested for the tensile strength of the membrane and the proton conductivity at different temperatures according to Part 3 of GB / T 20042.3 - 2009. The test method for the hydrogen permeation current was an electrochemical method. The degree of damage to the proton membrane was judged by detecting the fluoride ion content through Fenton's reagent. The lower the fluoride ion content, the lower the degree of membrane damage.

[0076] The results are shown in Table 2.

[0077] Table 2 Proton Membrane Performance Test

[0078]

[0079] The foregoing description of the specific exemplary embodiments of the present invention is for the purposes of illustration and exemplification. These descriptions are not intended to limit the invention to the precise forms disclosed, and obviously, many changes and variations are possible in light of the above teaching. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical applications, so that those skilled in the art can implement and utilize the various different exemplary embodiments of the invention, as well as various different selections and changes. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A proton membrane with a tetrafluoroethylene membrane as the skeleton, characterized in that, The proton membrane is composed of a tetrafluoroethylene membrane as the skeleton and a mixed coating is coated on both sides. The mixed coating is prepared from the following raw materials in parts by weight: 30-35 wt% of perfluorosulfonic acid solution, 2-4 wt% of triaminosilane coupling agent modified silica, and the balance is a high-boiling solvent; The triaminosilane coupling agent is N-(piperazinylethyl)-3-aminopropylmethyldimethoxysilane; The high-boiling solvent includes one of N-N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, and N-N-dimethylacetamide.

2. The proton membrane with a tetrafluoroethylene membrane as the skeleton according to claim 1, characterized in that, The thickness of the tetrafluoroethylene membrane is 10-20 μm, the porosity is ≥80%, and the pore diameter is 0.3-0.5 μm.

3. The proton membrane with a tetrafluoroethylene membrane as the framework according to claim 1, characterized in that, The perfluorosulfonic acid solution is composed of the following raw materials in weight percentages: 15-20 wt% of perfluorosulfonic acid resin, 80-85 wt% of low-boiling alcohol solution.

4. The proton membrane with a tetrafluoroethylene membrane as the skeleton according to claim 3, characterized in that, The low-boiling alcohol solution is anhydrous isopropanol.

5. The proton membrane with a tetrafluoroethylene membrane as the skeleton according to claim 1, characterized in that, The triaminosilane coupling agent modified silica is prepared by the following method: (1) Reflux the fumed silica in an ethanol solution of dilute hydrochloric acid at 85-90 °C for 55-60 h, and centrifuge at 8000-9000 r / min for 5-10 min to obtain mesoporous silica particles; wherein, the volume ratio of HCL:ethanol is 1:20; (2) Mix the mesoporous silica particles and the triaminosilane coupling agent in a weight ratio of 1:0.05 and stir at 180-200 rpm for 18-20 h, and centrifuge at 8000-9000 r / min for 5-10 min to obtain triaminosilane coupling agent modified silica.

6. A method for preparing the proton membrane with a tetrafluoroethylene membrane as the skeleton according to claim 4, characterized in that, It includes the following steps: (1) Take anhydrous isopropanol and perfluorosulfonic acid resin, heat and dissolve in a reaction kettle at 1.5±0.2 MPa for 5-6 h to obtain perfluorosulfonic acid solution; (2) Take the perfluorosulfonic acid solution and the high-boiling solvent and mix and stir at 300-400 rpm for 10-15 min to obtain a mixed solution; (3) Then add triaminosilane coupling agent modified silica to the mixed solution in step (2), mix and stir at 300-400 rpm for 10-15 min, and then ultrasonically irradiate at an ultrasonic power of 500-600 w and a temperature of 40-45 °C for 50-60 min to obtain a mixed coating solution; (4) Take anhydrous isopropanol to infiltrate the tetrafluoroethylene membrane to make it transparent, uniformly coat the mixed coating solution in step (3) on both sides of the tetrafluoroethylene membrane, heat-treat at 140-150 °C for 60-70 min, and then cure at 160-175 °C for 1-2 h to obtain it.

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