PVDF (Polyvinylidene Fluoride) composite perfluorosulfonic acid proton exchange membrane as well as preparation method and application thereof

Abstract

The invention discloses a PVDF composite perfluorosulfonic acid proton exchange membrane and a preparation method and application thereof.The PVDF composite perfluorosulfonic acid proton exchange membrane is of a layered structure, the layered structure sequentially comprises a first perfluorosulfonic acid layer, a polyvinylidene fluoride membrane and a second perfluorosulfonic acid layer from top to bottom, the first perfluorosulfonic acid layer comprises perfluorosulfonic acid resin and ferrous titanate, and the second perfluorosulfonic acid layer comprises perfluorosulfonic acid resin and ferrous titanate; the first perfluorosulfonic acid layer comprises perfluorosulfonic acid resin and ferrous titanate, the second perfluorosulfonic acid layer comprises perfluorosulfonic acid resin and ferrous titanate, the polyvinylidene fluoride membrane comprises polyvinylidene fluoride and ionic liquid, and the PVDF composite perfluorosulfonic acid proton exchange membrane has good mechanical properties, proton conductivity, water absorption and hydrolytic stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery separators, and in particular relates to a PVDF composite perfluorosulfonic acid proton exchange membrane and a preparation method and application thereof. Background Art

[0002] Energy is a key pillar of human development. Traditional fossil fuels played a crucial role in the two industrial revolutions, significantly boosting productivity and accelerating human progress. However, the use of fossil fuels also brings numerous problems: greenhouse gas emissions lead to environmental pollution, traditional internal combustion engines have low energy efficiency, and non-renewable fossil fuels are unable to meet growing energy demand. This overreliance on fossil fuels not only threatens global energy security but also exacerbates the severe situation of environmental pollution.

[0003] Proton exchange membrane fuel cells (PEMFCs) use an ion-conducting polymer membrane as the electrolyte. Operating in the 60-100°C range, they are classified as low-temperature fuel cells and boast a short startup time. Compared to other fuel cell types, PEMFCs also offer advantages such as compact size and zero-pollution emissions, such as water emissions. Consequently, they are highly anticipated as a power source for automobiles and are currently a mainstream area of ​​fuel cell research. As the core component of the membrane electrode assembly (MEA), the proton exchange membrane (PEM) performs proton transfer, isolates bipolar reactants, and blocks electron conduction. Furthermore, given the complex environmental conditions encountered during PEMFC operation, the PEM must also possess certain chemical and mechanical stability. Currently under research, PEM materials primarily include perfluorosulfonic acid, partially sulfonated, and aromatic sulfonated membrane materials. Nafion membranes are widely used in the commercial sector. However, Nafion membranes still have the following drawbacks: the synthesis and sulfonation of perfluorinated materials are extremely difficult, and hydrolysis and sulfonation during the membrane formation process easily denature and degrade the polymer, making membrane formation difficult. This leads to high costs and insufficient hydrolytic stability, proton conductivity, and mechanical properties. Domestic scholars have conducted extensive research to address these shortcomings, but the above issues have not yet been fully resolved. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a PVDF composite perfluorosulfonic acid proton exchange membrane.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned PVDF composite perfluorosulfonic acid proton exchange membrane.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] A PVDF composite perfluorosulfonic acid proton exchange membrane, wherein the PVDF composite perfluorosulfonic acid proton exchange membrane is a layered structure, wherein the layered structure is sequentially composed of: a first perfluorosulfonic acid layer, a polyvinylidene fluoride (PVDF) membrane, and a second perfluorosulfonic acid layer from top to bottom.

[0008] The first perfluorosulfonic acid layer comprises: perfluorosulfonic acid resin and iron (II) titanate,

[0009] The second perfluorosulfonic acid layer includes perfluorosulfonic acid resin and iron (II) titanate,

[0010] Polyvinylidene fluoride (PVDF) membrane includes: polyvinylidene fluoride and ionic liquid,

[0011] Calculated by mass, the ratio of iron (II) titanate in the first perfluorosulfonic acid layer, perfluorosulfonic acid resin in the first perfluorosulfonic acid layer, iron (II) titanate in the second perfluorosulfonic acid layer, perfluorosulfonic acid resin in the second perfluorosulfonic acid layer, polyvinylidene fluoride in the polyvinylidene fluoride (PVDF) membrane, and ionic liquid in the polyvinylidene fluoride (PVDF) membrane is (0.5-5): (60-82): (0.5-5): (60-82): (10-30): (1-3), and the ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt.

[0012] In the above technical solution, the first perfluorosulfonic acid layer and the second perfluorosulfonic acid layer are the same or different.

[0013] In the above technical solution, the thickness of the first perfluorosulfonic acid layer is 20-35 μm, the thickness of the second perfluorosulfonic acid layer is 20-35 μm, and the thickness of the polyvinylidene fluoride (PVDF) membrane is 5-20 μm.

[0014] In the above technical solution, the thickness of the first perfluorosulfonic acid layer is preferably 20-25 μm, the thickness of the second perfluorosulfonic acid layer is preferably 20-25 μm, and the thickness of the polyvinylidene fluoride (PVDF) membrane is preferably 10-15 μm.

[0015] In the above technical solution, the ratio of iron (II) titanate in the first perfluorosulfonic acid layer, perfluorosulfonic acid resin in the first perfluorosulfonic acid layer, iron (II) titanate in the second perfluorosulfonic acid layer, perfluorosulfonic acid resin in the second perfluorosulfonic acid layer, polyvinylidene fluoride in the polyvinylidene fluoride (PVDF) membrane and ionic liquid in the polyvinylidene fluoride (PVDF) membrane is preferably (1.2-1.6): (65-80): (1.2-1.6): (65-80): (20-30): (1.2-1.6).

[0016] The preparation method of the PVDF composite perfluorosulfonic acid proton exchange membrane comprises: casting a perfluorosulfonic acid solution on a substrate, placing a polyvinylidene fluoride (PVDF) membrane, heating for the first time, then casting the perfluorosulfonic acid solution on the upper surface of the polyvinylidene fluoride (PVDF) membrane, heating for the second time to obtain a first perfluorosulfonic acid layer on the lower surface of the polyvinylidene fluoride (PVDF) membrane and a second perfluorosulfonic acid layer on the upper surface of the polyvinylidene fluoride (PVDF) membrane, and post-processing to obtain the PVDF composite perfluorosulfonic acid proton exchange membrane.

[0017] In the above technical solution, the first heating includes: heating at 60-100° C. for 2-5 hours.

[0018] In the above technical solution, the second heating includes: first drying at 60-100° C. for 8-24 hours, and then drying at 80-150° C. for 1-3 hours.

[0019] In the above technical solution, the post-treatment includes: soaking in hydrogen peroxide at 60-100°C (the concentration of hydrogen peroxide is 2-5wt%), water at 60-100°C, sulfuric acid at 60-100°C (the concentration of sulfuric acid is 0.5-2 mol / L) and water at 60-100°C for 0.5-2 hours each.

[0020] In the above technical solution, the method for obtaining a polyvinylidene fluoride (PVDF) membrane includes: electrospinning a polyvinylidene fluoride (PVDF) spinning solution to form fibers under the action of a high-voltage electrostatic field, which are received by a receiving substrate, and obtaining a polyvinylidene fluoride (PVDF) membrane on the receiving substrate. The polyvinylidene fluoride (PVDF) spinning solution includes: polyvinylidene fluoride, an ionic liquid and a first solvent. In terms of mass fractions, the ratio of the polyvinylidene fluoride, the ionic liquid and the first solvent is (10 to 30): (1 to 3): (67 to 89).

[0021] In the method for obtaining a polyvinylidene fluoride (PVDF) membrane, the voltage of the electrospinning is 18 to 28 kV.

[0022] In the method for obtaining a polyvinylidene fluoride (PVDF) membrane, the propulsion speed of the syringe during the electrospinning process is 0.2 to 0.8 mL / h.

[0023] In the method for obtaining a polyvinylidene fluoride (PVDF) membrane, the electrospinning time is 5 to 18 hours.

[0024] In the method for obtaining a polyvinylidene fluoride (PVDF) membrane, the method for preparing a polyvinylidene fluoride (PVDF) spinning solution includes: mixing polyvinylidene fluoride, an ionic liquid and a first solvent until uniform (forming a transparent viscous liquid) to obtain a polyvinylidene fluoride (PVDF) spinning solution, wherein, in parts by mass, the ratio of the polyvinylidene fluoride, the ionic liquid and the first solvent is (10 to 30): (1 to 3): (67 to 89).

[0025] In the above technical solution, the ratio of the polyvinylidene fluoride, the ionic liquid and the first solvent is preferably (20-30): (1.2-1.6): (70-80) in parts by mass.

[0026] In the method for preparing a polyvinylidene fluoride (PVDF) spinning solution, the first solvent is at least one of N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), m-cresol, and N,N-dimethylformamide (DMF).

[0027] In the method for preparing a polyvinylidene fluoride (PVDF) spinning solution, polyvinylidene fluoride, an ionic liquid, and a first solvent are mixed and stirred at 40 to 70° C. until uniform. The stirring speed is 300 to 500 r / min and the stirring time is 2 to 8 hours.

[0028] In the above technical solution, the perfluorosulfonic acid solution includes: iron (II) titanate (FeTiO3), perfluorosulfonic acid resin and a second solvent. The ratio of the iron (II) titanate, perfluorosulfonic acid resin and the second solvent is (0.5-5): (60-82): (750-1200) by mass.

[0029] In the above technical solution, the method for obtaining a perfluorosulfonic acid solution includes: mixing iron (II) titanate (FeTiO3), a perfluorosulfonic acid resin, and a second solvent until uniform to obtain a perfluorosulfonic acid solution, wherein, by mass, the ratio of the iron (II) titanate, the perfluorosulfonic acid resin, and the second solvent is (0.5-5): (60-82): (750-1200).

[0030] In the above technical solution, the ratio of the iron (II) titanate, the perfluorosulfonic acid resin and the second solvent is preferably (1.2-1.6): (65-80): (800-900) in parts by mass.

[0031] In the method for obtaining a perfluorosulfonic acid solution, the second solvent is a mixture of water and anhydrous ethanol, and the ratio of water in the second solvent to anhydrous ethanol in the second solvent is (1-5):(1-2) by mass.

[0032] Application of polyvinylidene fluoride (PVDF), perfluorosulfonic acid resin, ferrous titanate and ionic liquid to improve the mechanical properties, proton conductivity, water absorption and hydrolytic stability of proton exchange membranes.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention affects the polyvinylidene fluoride electrospinning process through the excellent solubility properties of ionic liquids, thereby making the polyvinylidene fluoride spinning more uniform;

[0035] 2. Ferrous titanate has good hydrophilicity. The synergistic effect of perfluorosulfonic acid and iron titanate (II) makes the PVDF composite perfluorosulfonic acid proton exchange membrane exhibit higher water absorption and proton conductivity.

[0036] 3. Use polyvinylidene fluoride (PVDF) membrane as the middle layer to provide support and provide good mechanical properties for the diaphragm.

[0037] 4. The PVDF composite perfluorosulfonic acid proton exchange membrane of the present invention has good mechanical properties, proton conductivity, water absorption and hydrolysis stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a SEM image of the PVDF composite perfluorosulfonic acid proton exchange membrane prepared in Example 2;

[0039] Figure 2 This is the SEM of the composite multilayer hybrid proton exchange membrane prepared in Comparative Example 2. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described below with reference to specific embodiments.

[0041] The information of the raw materials involved in the following examples and comparative examples is as follows:

[0042] Perfluorosulfonic acid resin (powder), purity 98%, Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.

[0043] N-Methylpyrrolidone (NMP), purity 99.5%, Tianjin Hengxing Chemical Reagent Manufacturing Co., Ltd.

[0044] 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, purity 99%, Shanghai MacLean Biochemical Technology Co., Ltd.;

[0045] Polyvinylidene fluoride (PVDF), melt viscosity 2200 Pa.S, product number: P741973, Aladdin;

[0046] Iron(II) titanate, 99.9%, Merck, USA;

[0047] 1-Butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide salt, 98%, Aladdin.

[0048] The models and manufacturers of the equipment involved in the following examples and comparative examples are as follows:

[0049] Scanning electron microscope, Sigma 300, Carl Zeiss, Germany;

[0050] Japan Shimadzu stretching machine, AGS-X (100N);

[0051] Electrochemical workstation, CHI660E, Shanghai Chenhua Instrument Co., Ltd.

[0052] The test method in the following examples is as follows:

[0053] Hydrolytic stability value: A pre-dried membrane with a mass of Wo (g) is immersed in deionized water at 80°C for 48 hours. The membrane is then taken out and dried at 80°C for 8 hours. The mass of the membrane is then measured as Wt (g). The hydrolytic stability value Wc of the membrane is calculated using the following formula:

[0054]

[0055] Water absorption rate: Dry the membrane in an oven at 80℃±2℃ for 24 hours, take it out and dry it to room temperature. Measure the mass of the membrane as m0 (g). Then soak the membrane in distilled water at 80℃ for 8 hours. Use filter paper to remove water on the membrane surface. Measure the mass of the membrane within 30 seconds as m1 (g). The water absorption rate Δm is calculated by the following formula:

[0056]

[0057] The membrane was made into rectangular specimens with a length of 65 mm and a width of 15 mm. A Shimadzu tensile machine was used to test the mechanical properties and elongation at break. The tensile speed was set to 5 mm / min and the original gauge length was 20 mm.

[0058] The mechanical properties (tensile strength) are calculated by the following formula:

[0059] σ1=p / (b×d), where σ1 is tensile strength (MPa), p is maximum load (N), b is width of rectangular spline (mm), and d is thickness of rectangular spline (mm). The thickness is measured by a thickness gauge.

[0060] The elongation at break is calculated by the following formula:

[0061] Where, e is the elongation at break, l0 is the length of the rectangular spline, l a is the length of the rectangular spline at break.

[0062] Proton conductivity (PC): The test was conducted at a temperature of 25° C. and a humidity of 100% RH.

[0063] Examples 1 to 5

[0064] A PVDF composite perfluorosulfonic acid proton exchange membrane, the PVDF composite perfluorosulfonic acid proton exchange membrane is a layered structure, the layered structure from top to bottom is: a first perfluorosulfonic acid layer, a polyvinylidene fluoride (PVDF) membrane and a second perfluorosulfonic acid layer,

[0065] The first perfluorosulfonic acid layer comprises: perfluorosulfonic acid resin and iron (II) titanate,

[0066] The second perfluorosulfonic acid layer includes perfluorosulfonic acid resin and iron (II) titanate,

[0067] Polyvinylidene fluoride (PVDF) membrane includes: polyvinylidene fluoride and ionic liquid,

[0068] The ratio of iron (II) titanate in the first perfluorosulfonic acid layer, perfluorosulfonic acid resin in the first perfluorosulfonic acid layer, iron (II) titanate in the second perfluorosulfonic acid layer, perfluorosulfonic acid resin in the second perfluorosulfonic acid layer, polyvinylidene fluoride in the polyvinylidene fluoride (PVDF) membrane, and ionic liquid in the polyvinylidene fluoride (PVDF) membrane is Z, and the ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt.

[0069] The first perfluorosulfonic acid layer and the second perfluorosulfonic acid layer are the same, and the thickness of the first perfluorosulfonic acid layer and the second perfluorosulfonic acid layer are both A μm. The thickness of the polyvinylidene fluoride (PVDF) membrane is B μm.

[0070] The preparation method of the PVDF composite perfluorosulfonic acid proton exchange membrane comprises the following steps: casting a perfluorosulfonic acid solution on a substrate, placing a polyvinylidene fluoride (PVDF) membrane, heating for the first time (heating at 80°C for 3 hours), then casting the perfluorosulfonic acid solution on the upper surface of the polyvinylidene fluoride (PVDF) membrane, heating for the second time (first drying at 80°C for 12 hours, then drying at 120°C for 1.5 hours), obtaining a second perfluorosulfonic acid layer on the upper surface of the polyvinylidene fluoride (PVDF) membrane and forming a second perfluorosulfonic acid layer on the upper surface of the polyvinylidene fluoride (PVDF) membrane. A first perfluorosulfonic acid layer is obtained on the lower surface of a polyvinyl chloride (PVDF) membrane, and post-treatment is performed to obtain a PVDF composite perfluorosulfonic acid proton exchange membrane, the post-treatment comprising: soaking in 80°C hydrogen peroxide (3wt%) for 1 hour, taking out the diaphragm, washing with deionized water, soaking in 80°C deionized water for 1 hour, soaking in 80°C 1mol / L sulfuric acid for 1 hour, taking out the diaphragm, washing with deionized water, soaking in 80°C deionized water for 1 hour, taking out the diaphragm, and drying at 80°C for 12 hours.

[0071] The method for obtaining a polyvinylidene fluoride (PVDF) membrane includes: electrospinning a polyvinylidene fluoride (PVDF) spinning solution (drying it with a 40°C heating lamp during the process from spraying from a spinning needle to being received by a receiving substrate), forming fibers under the action of a high-voltage electrostatic field (the voltage of electrospinning is 25KV), being received by a receiving substrate, and obtaining a polyvinylidene fluoride (PVDF) membrane on the receiving substrate. During the electrospinning process, the propulsion speed of the syringe is 0.5mL / h, and the electrospinning time is 6h.

[0072] The method for preparing a polyvinylidene fluoride (PVDF) spinning solution includes: mixing polyvinylidene fluoride, an ionic liquid and a first solvent, stirring at 60°C and a speed of 400 r / min for 6 hours until uniform (forming a transparent viscous liquid), to obtain a polyvinylidene fluoride (PVDF) spinning solution, wherein the ratio of polyvinylidene fluoride, the ionic liquid and the first solvent is X in parts by mass, and the first solvent is N-methylpyrrolidone (NMP).

[0073] The method for obtaining a perfluorosulfonic acid solution includes: mixing iron (II) titanate (FeTiO3), a perfluorosulfonic acid resin, and a second solvent until uniform, to obtain a perfluorosulfonic acid solution, wherein, by weight, the ratio of iron (II) titanate, the perfluorosulfonic acid resin, and the second solvent is Y, the second solvent is a mixture of water and anhydrous ethanol, and by weight, the ratio of water in the second solvent to anhydrous ethanol in the second solvent is 5:1.5.

[0074] X, Y, Z, A and B are shown in Table 1. By changing the values ​​of X and Y, the PVDF composite perfluorosulfonic acid proton exchange membranes of Examples 1 to 5 were obtained.

[0075] Table 1

[0076]

[0077]

[0078] Comparative Example 1

[0079] A method for preparing a ferrous titanate-modified perfluorosulfonic acid resin proton exchange membrane comprises: casting a perfluorosulfonic acid solution on a substrate, drying it at 80°C for 12 hours, then drying it at 120°C for 1.5 hours, and post-treating it (the same post-treating method as in Example 1) to obtain a ferrous titanate-modified perfluorosulfonic acid resin proton exchange membrane, wherein the method for obtaining the perfluorosulfonic acid solution in Comparative Example 1 comprises: mixing ferrous titanate (II) FeTiO3, a perfluorosulfonic acid resin, and a second solvent until uniformly mixed to obtain the perfluorosulfonic acid solution, wherein, by mass, the ratio of ferrous titanate (II), the perfluorosulfonic acid resin, and the second solvent is 3:70:921.5, and the second solvent is a mixture of water and anhydrous ethanol, and by mass, the ratio of water to anhydrous ethanol is 5:1.5.

[0080] Comparative Example 2

[0081] A method for preparing a composite multilayer hybrid proton exchange membrane is basically the same as that in Example 2, except that the polyvinylidene fluoride (PVDF) spinning solution is different. The method for obtaining the polyvinylidene fluoride (PVDF) spinning solution in Comparative Example 2 includes: mixing polyvinylidene fluoride and NMP, stirring at 60°C and 400 r / min for 6 hours until uniform, to obtain a polyvinylidene fluoride (PVDF) spinning solution, wherein the ratio of polyvinylidene fluoride to NMP is 25:75 by mass.

[0082] The composite multilayer hybrid proton exchange membrane prepared in Comparative Example 2 has a layered structure, and the layered structure is as follows from top to bottom: a first perfluorosulfonic acid layer, a polyvinylidene fluoride (PVDF) membrane and a second perfluorosulfonic acid layer. The first perfluorosulfonic acid layer in Comparative Example 2 is the same as the first perfluorosulfonic acid layer in Example 2, and the second perfluorosulfonic acid layer in Comparative Example 2 is the same as the second perfluorosulfonic acid layer in Example 2. The thickness of the polyvinylidene fluoride (PVDF) membrane in Comparative Example 2 is 10.20 μm.

[0083] Comparative Example 3

[0084] A preparation method of a PVDF composite perfluorosulfonic acid proton exchange membrane comprises the following steps: casting a perfluorosulfonic acid solution on a substrate, placing a polyvinylidene fluoride (PVDF) membrane, heating for the first time (heating at 80°C for 3 hours), casting the perfluorosulfonic acid solution on the upper surface of the polyvinylidene fluoride (PVDF) membrane, heating for the second time (drying at 80°C for 12 hours and then drying at 120°C for 1.5 hours), obtaining a first perfluorosulfonic acid layer on the lower surface of the polyvinylidene fluoride (PVDF) membrane and a first perfluorosulfonic acid layer on the lower surface of the polyvinylidene fluoride (PVDF) membrane. A second perfluorosulfonic acid layer is obtained on the upper surface of the (PVDF) membrane, and post-treatment is performed to obtain a PVDF composite perfluorosulfonic acid proton exchange membrane, and the post-treatment includes: soaking in hydrogen peroxide (3wt%) at 80°C for 1 hour, removing the membrane, washing with deionized water, soaking in deionized water at 80°C for 1 hour, soaking in 1 mol / L sulfuric acid at 80°C for 1 hour, removing the membrane, washing with deionized water, soaking in deionized water at 80°C for 1 hour, removing the membrane, and drying at 80°C for 12 hours.

[0085] The method for obtaining the polyvinylidene fluoride (PVDF) membrane in Comparative Example 3 includes: electrospinning the polyvinylidene fluoride (PVDF) spinning solution (drying it with a 40°C heating lamp during the spinning process), forming fibers under the action of a high-voltage electrostatic field (the voltage of electrospinning is 25KV), and being received by a receiving substrate to obtain a polyvinylidene fluoride (PVDF) membrane on the receiving substrate. The propulsion speed of the syringe during the electrospinning process is 0.5mL / h, and the electrospinning time is 6h. The method for preparing a polyvinylidene fluoride (PVDF) spinning solution includes: mixing polyvinylidene fluoride and NMP, stirring at a speed of 400r / min at 60°C for 6h until uniform (forming a transparent viscous liquid), and obtaining a polyvinylidene fluoride (PVDF) spinning solution, wherein the ratio of polyvinylidene fluoride to NMP is 25:75 by mass.

[0086] The method for obtaining a perfluorosulfonic acid solution includes: mixing a perfluorosulfonic acid resin and a second solvent until uniform to obtain the perfluorosulfonic acid solution, wherein the ratio of the perfluorosulfonic acid resin to the second solvent is 70:900 by mass, and the second solvent is a mixture of water and anhydrous ethanol, and the ratio of water to anhydrous ethanol is 5:1.5 by mass.

[0087] The PVDF composite perfluorosulfonic acid proton exchange membrane prepared in Comparative Example 3 has a layered structure, and the layered structure is as follows from top to bottom: a first perfluorosulfonic acid layer, a polyvinylidene fluoride (PVDF) membrane, and a second perfluorosulfonic acid layer. The first perfluorosulfonic acid layer and the second perfluorosulfonic acid layer in Comparative Example 3 are the same. The thickness of the first perfluorosulfonic acid layer and the second perfluorosulfonic acid layer in Comparative Example 3 are both 23.00 μm, and the thickness of the polyvinylidene fluoride (PVDF) membrane in Comparative Example 3 is 10.51 μm.

[0088] Comparative Example 4

[0089] A preparation method of a PVDF composite perfluorosulfonic acid proton exchange membrane is basically the same as that in Example 3, except that "the ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide" is replaced by "the ionic liquid is 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide".

[0090] The PVDF composite perfluorosulfonic acid proton exchange membrane prepared in Comparative Example 4 has a layered structure, and the layered structure is as follows from top to bottom: a first perfluorosulfonic acid layer, a polyvinylidene fluoride (PVDF) membrane, and a second perfluorosulfonic acid layer. The first perfluorosulfonic acid layer and the second perfluorosulfonic acid layer in Comparative Example 4 are the same. The thickness of the first perfluorosulfonic acid layer and the second perfluorosulfonic acid layer in Comparative Example 4 are both 22.45 μm, and the thickness of the polyvinylidene fluoride (PVDF) membrane in Comparative Example 4 is 10.56 μm.

[0091] Comparative Example 5

[0092] A method for preparing a PVDF composite perfluorosulfonic acid proton exchange membrane is substantially the same as that of Example 2, except that iron (II) titanate is not added when preparing the perfluorosulfonic acid solution.

[0093] The PVDF composite perfluorosulfonic acid proton exchange membrane prepared in Comparative Example 5 has a layered structure, and the layered structure is as follows from top to bottom: a first perfluorosulfonic acid layer, a polyvinylidene fluoride (PVDF) membrane, and a second perfluorosulfonic acid layer. The first perfluorosulfonic acid layer and the second perfluorosulfonic acid layer in Comparative Example 5 are the same. The thickness of the first perfluorosulfonic acid layer and the second perfluorosulfonic acid layer in Comparative Example 5 are both 22.34 μm, and the thickness of the polyvinylidene fluoride (PVDF) membrane in Comparative Example 5 is 10.69 μm.

[0094] Performance tests were performed on the PVDF composite perfluorosulfonic acid proton exchange membranes prepared in Examples 1 to 5, the ferrous titanate modified perfluorosulfonic acid resin proton exchange membranes prepared in Comparative Example 1, the composite multilayer hybrid proton exchange membranes prepared in Comparative Example 2, and the PVDF composite perfluorosulfonic acid proton exchange membranes prepared in Comparative Examples 3 to 5, as shown in Table 2.

[0095] Table 2

[0096]

[0097]

[0098] As shown in Table 2, in Examples 1 to 5, the PVDF composite perfluorosulfonic acid proton exchange membrane prepared in Example 2 exhibited excellent tensile strength, elongation at break, proton conductivity (proton conductivity), water absorption, and hydrolytic stability. By comparing Examples 1 to 5 with Comparative Examples 1 to 5, it can be seen that the present invention achieves the advantages of good mechanical properties, high proton conductivity, good water absorption, and good hydrolytic stability through the synergistic effect of PVDF, PFSA, ferrous titanate, and ionic liquid.

[0099] pass Figure 1 and Figure 2 It can be seen that after the introduction of ionic liquid, the fibers in the polyvinylidene fluoride (PVDF) membrane are more uniform, making the PVDF composite perfluorosulfonic acid proton exchange membrane have more excellent performance.

[0100] The above is an exemplary description of the present invention. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by other skilled in the art without expending creative labor falls within the scope of protection of the present invention.

Claims

1. A PVDF composite perfluorosulfonic acid proton exchange membrane, characterized in that: The PVDF composite perfluorosulfonic acid proton exchange membrane has a layered structure, which comprises, from top to bottom, a first perfluorosulfonic acid layer, a polyvinylidene fluoride membrane, and a second perfluorosulfonic acid layer. The first perfluorosulfonic acid layer comprises a perfluorosulfonic acid resin and ferrous titanate, the second perfluorosulfonic acid layer comprises a perfluorosulfonic acid resin and ferrous titanate, and the polyvinylidene fluoride membrane comprises polyvinylidene fluoride and an ionic liquid. The ratio of ferrous titanate in the first perfluorosulfonic acid layer, the perfluorosulfonic acid resin in the first perfluorosulfonic acid layer, the ferrous titanate in the second perfluorosulfonic acid layer, the perfluorosulfonic acid resin in the second perfluorosulfonic acid layer, the polyvinylidene fluoride in the polyvinylidene fluoride membrane, and the ionic liquid in the polyvinylidene fluoride membrane is (0.5-5):(60-82):(0.5-5):(60-82):(10-30):(1-3), and the ionic liquid is 1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt.

2. The PVDF composite perfluorosulfonic acid proton exchange membrane according to claim 1, characterized in that: The thickness of the first perfluorosulfonic acid layer is 20 to 35 μm, the thickness of the second perfluorosulfonic acid layer is 20 to 35 μm, and the thickness of the polyvinylidene fluoride film is 5 to 20 μm.

3. The method for preparing a PVDF composite perfluorosulfonic acid proton exchange membrane according to claim 1 or 2, wherein: include: The perfluorosulfonic acid solution is cast on a substrate, a polyvinylidene fluoride membrane is placed thereon, and the perfluorosulfonic acid solution is cast on the upper surface of the polyvinylidene fluoride membrane, and the perfluorosulfonic acid solution is heated for a second time and post-treated to obtain a PVDF composite perfluorosulfonic acid proton exchange membrane.

4. The preparation method according to claim 3, characterized in that The post-treatment comprises: soaking in hydrogen peroxide, water, sulfuric acid and water in sequence.

5. The preparation method according to claim 3, characterized in that The polyvinylidene fluoride membrane is obtained by electrostatic spinning of a polyvinylidene fluoride spinning solution, wherein the polyvinylidene fluoride spinning solution comprises: polyvinylidene fluoride, an ionic liquid and a first solvent, and the ratio of the polyvinylidene fluoride, the ionic liquid and the first solvent is (10-30): (1-3): (67-89) by mass.

6. The preparation method according to claim 5, characterized in that The first solvent is at least one of N-methylpyrrolidone, dimethyl sulfoxide, m-cresol and N,N-dimethylformamide.

7. The preparation method according to claim 5, characterized in that The perfluorosulfonic acid solution comprises: ferrous titanate, perfluorosulfonic acid resin and a second solvent. Calculated by mass, the ratio of the ferrous titanate, the perfluorosulfonic acid resin and the second solvent is (0.5-5): (60-82): (750-1200).

8. The preparation method according to claim 7, characterized in that The second solvent is a mixture of water and anhydrous ethanol, and the ratio of water in the second solvent to anhydrous ethanol in the second solvent is (1-5):(1-2) in parts by mass.

9. Application of polyvinylidene fluoride, perfluorosulfonic acid resin, ferrous titanate and ionic liquids to improve the mechanical properties / proton conductivity / water absorption / hydrolytic stability of proton exchange membranes.

10. The use according to claim 9, characterized in that The ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

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