Asymmetrically modified silica particles doped sulfonated poly(ether ether ketone) membranes, methods of making and use thereof

Abstract

The application provides an asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane and a preparation method and application thereof, the preparation method comprising the following steps: (1) under a heating condition, mixing surface hydroxylated silica particles and paraffin wax, then adding a first solvent to stir, and then cooling to obtain paraffin wax emulsion droplets; (2) mixing the paraffin wax emulsion droplets obtained in the step (1) and a thiol-containing silane coupling agent to react, to obtain a mixture; mixing the mixture with a hydrogen peroxide solution to perform an oxidation reaction, to obtain the asymmetrically modified silica particles; (3) mixing the asymmetrically modified silica particles with sulfonated polyether ether ketone and drying to obtain the asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane. The asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane provided by the application has low swelling, high proton conductivity and good ion selectivity, and can improve the performance of a liquid flow battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new energy materials, and particularly relates to an asymmetrically modified silica particle doped sulfonated poly (ether ether ketone) membrane, a preparation method and application thereof. BACKGROUND

[0002] Large-scale and efficient utilization of renewable energy (such as solar and wind energy) can significantly address the rapidly growing energy demand of modern society, while alleviating the resource constraints and environmental problems of fossil fuels. Long-time energy storage technology will play an increasingly important role in the grid connection of intermittent and unstable renewable energy power generation, improve the reliability and affordability of power generation systems, fill the seasonal energy storage solution, and reduce the cost of wind-solar cell power systems. Flow batteries are considered a very promising long-time energy storage technology, with fast response, power and capacity decoupling, long cycle life and environmental friendliness, which is very suitable for large-scale electrochemical energy storage.

[0003] As one of the key materials of flow batteries, ion exchange membranes are used to separate cathode and anode electrolytes and transfer conductive ions. An ideal ion exchange membrane should have low cost, good proton conductivity, high ion selectivity, good chemical and mechanical stability, etc., which is crucial to the cycle life and efficiency of the battery. The current commercialized liquid flow battery perfluorosulfonic acid ion exchange membrane (Nafion) has the advantages of good chemical stability and thermal stability, high conductivity, high mechanical strength, etc., but the high cost (500-700 US dollars per square meter) and low ion selectivity hinder the commercialization of flow batteries. The sulfonated poly (ether ether ketone) membrane material has high ion selectivity, low cost and excellent chemical and mechanical stability. CN104209023A blends uniformly sulfonated silica microspheres with sulfonated poly (ether ether ketone) to prepare a hybrid membrane, which is applied to CO2 / CH4 gas separation and has high selectivity and permeability, but the hydrogen bonding between the sulfonated silica microspheres and the sulfonated poly (ether ether ketone) is weakened, increasing the swelling of the hybrid membrane, which is not suitable for liquid flow battery ion exchange membranes. CN10980285A disperses and wraps uniformly sulfonated nanosilica in a sulfonated poly (ether ether ketone) membrane to ensure the thermal stability of the sulfonated poly (ether ether ketone) membrane, but the nanosilica particles are too small to ensure the ion conductivity and ion selectivity of the hybrid membrane, which is also not suitable for liquid flow battery ion exchange membranes.

[0004] In summary, the existing sulfonated poly (ether ether ketone) membrane has high swelling, poor ion selectivity and poor proton conductivity, so it is urgent to develop a high-performance sulfonated poly (ether ether ketone) membrane to improve the performance of the flow battery when used in the flow battery. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide an asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane and its preparation method and application. By designing the doping material of the sulfonated polyether ether ketone membrane, the ion selectivity and proton conductivity of the sulfonated polyether ether ketone membrane are improved, the swelling of the sulfonated polyether ether ketone membrane is reduced, the service life is prolonged, and the comprehensive performance of the sulfonated polyether ether ketone membrane for liquid flow battery is effectively improved.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In the first aspect, the present application provides a preparation method of an asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane, which comprises the following steps:

[0008] (1) Under heating conditions, mix the surface hydroxylated silica particles and paraffin wax, then add a first solvent for stirring, and then cool to obtain paraffin wax emulsion droplets;

[0009] (2) Mix the paraffin wax emulsion droplets obtained in step (1) and a thiol-containing silane coupling agent, and then react to obtain a mixture; mix the mixture with a hydrogen peroxide solution, and then perform an oxidation reaction to obtain the asymmetrically modified silica particles;

[0010] (3) Mix the asymmetrically modified silica particles and sulfonated polyether ether ketone, and then dry to obtain the asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane.

[0011] The asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane provided by the present application has the following advantages: on one side of the surface of the asymmetrically modified silica particles, there are hydroxyl groups, which can form hydrogen bonds with the sulfonated polyether ether ketone, thereby increasing the mechanical stability and thermal stability of the sulfonated polyether ether ketone membrane, reducing the swelling of the sulfonated polyether ether ketone membrane, and prolonging the service life of the sulfonated polyether ether ketone membrane; on the other side of the surface of the asymmetrically modified silica particles, there are sulfonic acid groups, which can increase the proton conductivity of the sulfonated polyether ether ketone membrane, thereby improving the performance of the liquid flow battery when used in the liquid flow battery.

[0012] In the present application, the sulfonated polyether ether ketone can be purchased through market channels or prepared by a known synthesis method in the art. For example, the preparation method of the sulfonated polyether ether ketone comprises: reacting polyether ether ketone with concentrated sulfuric acid, cooling, washing and drying after the reaction is completed, to obtain the sulfonated polyether ether ketone; the ratio of the polyether ether ketone to the concentrated sulfuric acid is 2g:(20-30)mL; the mass percentage concentration of the concentrated sulfuric acid is 98%; the cooling temperature is 15-20℃; the reaction time is 1-2h; and the reaction temperature is 50-70℃.

[0013] The following are preferred technical solutions of the present application, but not as a limitation of the technical solutions provided by the present application, through the following preferred technical solutions, the purpose and beneficial effects of the present application can be better achieved and realized.

[0014] As a preferred technical solution, the mass ratio of the surface hydroxylated silica particles to the paraffin is 1:(10-20), which can be 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19 or 1:20, etc.

[0015] In the present application, the surface hydroxylated silica particles can be purchased through market channels, or can be prepared by known synthesis methods in the art. Exemplarily, the preparation method of the surface hydroxylated silica particles comprises the following steps:

[0016] (S1) After mixing ammonia water and anhydrous ethanol, add them dropwise into tetraethyl orthosilicate for reaction to obtain silica particles; the mass percentage concentration of the ammonia water is 25%; the volume of the anhydrous ethanol is 90-110 mL; the volume ratio of the ammonia water to the tetraethyl orthosilicate is (10-20):2; the reaction temperature is 50-70℃.

[0017] (S2) After mixing the silica particles obtained in step (1), water, ammonia water and hydrogen peroxide, carry out reaction to obtain the surface hydroxylated silica particles; the mass percentage concentration of the ammonia water is 25%; the mass percentage concentration of the hydrogen peroxide is 30%; the volume ratio of the water, ammonia water and hydrogen peroxide is (5-7):1:1; the reaction temperature is 70-90℃; the reaction time is 4-6 min.

[0018] Preferably, the first solvent comprises water.

[0019] Preferably, the temperature of the heating in step (1) is 70-90℃, which can be 70℃, 72℃, 74℃, 76℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃ or 90℃, and specific point values between the above point values, limited to the length and for the sake of simplicity, the present application will not exhaustively list the specific point values included in the range.

[0020] Preferably, the temperature of the cooling in step (1) is 15-25℃, which can be 15℃, 16℃, 17℃, 18℃, 19℃, 20℃, 21℃, 22℃, 23℃, 24℃ or 25℃, and specific point values between the above point values, limited to the length and for the sake of simplicity, the present application will not exhaustively list the specific point values included in the range.

[0021] Preferably, the speed of the stirring is 6000-8000 r / min, for example, it can be 6000 r / min, 6200 r / min, 6400 r / min, 6600 r / min, 6800 r / min, 7000 r / min, 7200 r / min, 7400 r / min, 7600 r / min, 7800 r / min or 8000 r / min, and specific point values between the above-mentioned point values, limited to the length and for the sake of simplicity, the present application will not be listed again. The specific point values included in the range.

[0022] Preferably, the time of the stirring is 5-15 min, for example, it can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min or 15 min, and specific point values between the above-mentioned point values, limited to the length and for the sake of simplicity, the present application will not be listed again. The specific point values included in the range.

[0023] As a preferred technical solution, the thiol-containing silane coupling agent includes γ-mercaptopropyl trimethoxysilane and / or γ-mercaptopropyl triethoxysilane.

[0024] Preferably, the mass ratio of the thiol-containing silane coupling agent to the surface hydroxylated silicon dioxide particles is (3-8):1, for example, it can be 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1 or 8:1, etc.

[0025] Preferably, the temperature of the reaction in step (2) is 30-50℃, for example, it can be 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, 42℃, 44℃, 46℃, 48℃ or 50℃, and specific point values between the above-mentioned point values, limited to the length and for the sake of simplicity, the present application will not be listed again. The specific point values included in the range.

[0026] Preferably, the time of the reaction in step (2) is 20-28 h, for example, it can be 20 h, 21 h, 22 h, 23 h, 24 h, 25 h, 26 h, 27 h or 28 h, and specific point values between the above-mentioned point values, limited to the length and for the sake of simplicity, the present application will not be listed again. The specific point values included in the range.

[0027] Preferably, the reaction in step (2) is carried out in the presence of a second solvent.

[0028] Preferably, the second solvent includes water.

[0029] Preferably, the mass ratio of the second solvent to the paraffin emulsion droplets is (10-15):1, for example, it can be 10:1, 10.5:1, 11:1, 11.5:1, 12:1, 12.5:1, 13:1, 13.5:1, 14:1, 14.5:1, or 15:1, etc.

[0030] As a preferred technical solution, the temperature of the oxidation reaction is 30-50℃, for example, it can be 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, 42℃, 44℃, 46℃, 48℃, or 50℃, and specific point values between the above-mentioned point values. Due to the limitation of the length and the consideration of simplicity, the present application will not list the specific point values included in the range.

[0031] Preferably, the time of the oxidation reaction is 20-28h, for example, it can be 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, or 28h, and specific point values between the above-mentioned point values. Due to the limitation of the length and the consideration of simplicity, the present application will not list the specific point values included in the range.

[0032] Preferably, the mass percentage concentration of the hydrogen peroxide solution is 30%.

[0033] Preferably, the mass ratio of the hydrogen peroxide solution to the surface hydroxylated silica particles is (2-6):1, for example, it can be 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, or 6:1, etc.

[0034] As a preferred technical solution, after the oxidation reaction, the step of dissolving the paraffin with an organic solvent is further included.

[0035] Preferably, the organic solvent includes chloroform.

[0036] Preferably, the particle size of the asymmetrically modified silica particles is 190-210nm, for example, it can be 190nm, 192nm, 194nm, 196nm, 198nm, 200nm, 202nm, 204nm, 206nm, 208nm, or 210nm, and specific point values between the above-mentioned point values. Due to the limitation of the length and the consideration of simplicity, the present application will not list the specific point values included in the range.

[0037] The doping of the larger size asymmetrically modified silica particles makes the internal channel of the sulfonated polyether ether ketone membrane narrower and the branches more, which can reduce the migration speed of larger size ions in the membrane and improve the ion selectivity of the membrane.

[0038] As a preferred technical solution, the mass ratio of the asymmetrically modified silica particles and the sulfonated polyether ether ketone is (2.5-20):100, for example, it can be 2.5:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 10:100, 11:100, 13:100, 15:100, 16:100, 18:100 or 20:100, etc.

[0039] As a preferred technical solution, the mixed material in step (3) further comprises a third solvent.

[0040] Preferably, the third solvent comprises any one or a combination of at least two of N,N-dimethylformamide, dimethyl sulfoxide or N,N-dimethylacetamide.

[0041] Preferably, the ratio of the sulfonated polyether ether ketone and the third solvent is 1g:(40-60)mL, for example, it can be 1g:40mL, 1g:42mL, 1g:44mL, 1g:46mL, 1g:48mL, 1g:50mL, 1g:52mL, 1g:54mL, 1g:56mL, 1g:58mL or 1g:60mL, etc.

[0042] Preferably, the temperature of the mixing in step (3) is 50-70℃, for example, it can be 50℃, 52℃, 54℃, 56℃, 58℃, 60℃, 62℃, 64℃, 66℃, 68℃ or 70℃, and specific point values between the above point values, limited to the length and for the sake of simplicity, the present application does not exhaustively list the specific point values included in the range.

[0043] As a preferred technical solution, the preparation method specifically comprises the following steps:

[0044] (1) under heating conditions, the surface-hydroxylated silica particles and paraffin are mixed and then water is added for stirring, and then cooled to obtain paraffin emulsion droplets; the mass ratio of the surface-hydroxylated silica particles and paraffin is 1:(10-20); the temperature of the heating is 70-90℃; the temperature of the cooling is 15-25℃; the stirring speed is 6000-8000r / min; and the stirring time is 5-15min;

[0045] (2) mixing the paraffin wax emulsion droplets, water and thiol-containing silane coupling agent obtained in step (1) to react, to obtain a mixture; mixing the mixture with a hydrogen peroxide solution to perform an oxidation reaction, and dissolving the paraffin wax with an organic solvent after the oxidation reaction is completed, to obtain the asymmetrically modified silica particles; the mass ratio of the thiol-containing silane coupling agent to the surface hydroxylated silica particles is (3-8):1; the reaction temperature is 30-50℃; the reaction time is 20-28h; the mass ratio of the water to the paraffin wax emulsion droplets is (10-15):1; the oxidation reaction temperature is 30-50℃; the oxidation reaction time is 20-28h; the mass percentage concentration of the hydrogen peroxide solution is 30%; the mass ratio of the hydrogen peroxide solution to the surface hydroxylated silica particles is (2-6):1; and the particle size of the asymmetrically modified surface hydroxylated silica particles is 190-210nm;

[0046] (3) mixing the asymmetrically modified silica particles, a third solvent and sulfonated polyether ether ketone to dry, to obtain the asymmetrically modified silica particle-doped sulfonated polyether ether ketone membrane; the mass ratio of the asymmetrically modified silica particles to the sulfonated polyether ether ketone is (2.5-20):100; the ratio of the sulfonated polyether ether ketone to the third solvent is 1g:(40-60)mL; and the mixing temperature is 50-70℃.

[0047] In a second aspect, the present application provides an asymmetrically modified silica particle-doped sulfonated polyether ether ketone membrane, which is prepared by the preparation method of the first aspect.

[0048] Preferably, the thickness of the asymmetrically modified silica particle-doped sulfonated polyether ether ketone membrane is 70-90μm, for example, 70μm, 72μm, 74μm, 76μm, 78μm, 80μm, 82μm, 84μm, 86μm, 88μm or 90μm, and specific point values between the above point values, limited by the length and for the sake of simplicity, the present application does not list the specific point values included in the range.

[0049] In a third aspect, the present application provides a flow battery, which comprises the asymmetrically modified silica particle-doped sulfonated polyether ether ketone membrane of the second aspect.

[0050] Compared with the prior art, the present application has the following beneficial effects:

[0051] 1. The surface of the asymmetrically modified silica particles is hydroxyl group, which can form hydrogen bond with the sulfonated polyether ether ketone, increase the mechanical stability and thermal stability of the membrane, reduce the swelling of the membrane, and prolong the service life of the membrane, and the swelling rate of the membrane can be reduced to 10%-12%;

[0052] 2. The other side of the asymmetrically modified silica particle surface is grafted with sulfonic acid groups, which can increase the proton conductivity of the membrane, and the proton conductivity of the membrane can be increased to 0.04-0.05 S / cm; as an ion exchange membrane for a flow battery, the energy efficiency of the flow battery is 73%-80%, which can improve the performance of the flow battery;

[0053] 3. The doping of the larger size asymmetrically modified silica particles makes the internal channels of the sulfonated polyether ether ketone membrane narrower and the branches more, which can reduce the migration speed of larger size ions in the membrane and improve the ion selectivity of the membrane. DETAILED DESCRIPTION

[0054] In order to facilitate the understanding of the present application, the present application is illustrated by the following examples. It should be understood by those skilled in the art that the examples are only to help understand the present application and should not be regarded as specific limitations of the present application.

[0055] Some components in the examples and comparative examples are as follows:

[0056] (1) Surface-hydroxylated silica particles: the preparation method is as follows:

[0057] (S1) 15 mL of 25% mass percentage ammonia water and 100 mL of anhydrous ethanol were mixed, and then 2 mL of tetraethyl orthosilicate was added dropwise for reaction at a reaction temperature of 60°C. After the reaction was completed, the silica particles were obtained by repeated centrifugation and washing with anhydrous ethanol;

[0058] (S2) The silica particles obtained in step (1), 60 mL of deionized water, 10 mL of 25% mass percentage ammonia water, and 10 mL of 30% mass percentage hydrogen peroxide were mixed and reacted at 80°C for 5 min. After the reaction was completed, the surface-hydroxylated silica particles were obtained by repeated centrifugation and washing with anhydrous ethanol and vacuum drying.

[0059] (2) Sulfonated polyether ether ketone: the preparation method is as follows: 16 g of polyether ether ketone (purchased from VICTREX 450PF in the United Kingdom) was reacted with 200 mL of 98% mass percentage concentrated sulfuric acid at 400 r / min, the reaction temperature was 60°C, and the reaction time was 1.5 h. After the reaction was completed, the reaction mixture was cooled by pouring into cold water at 20°C, and then repeatedly washed until neutral, and then dried to obtain the sulfonated polyether ether ketone.

[0060] Example 1

[0061] An asymmetrically modified silica particle-doped sulfonated polyether ether ketone membrane and a preparation method thereof, the preparation method comprising the following steps:

[0062] (1) 80℃ conditions, 0.8 g of surface hydroxylated silica particles were mixed with 12 g of paraffin wax, then appropriate amount of deionized water was added, stirred at 7200 r / min for 10 min, then cooled to 20℃ by cold water bath, then washed with deionized water to obtain paraffin wax emulsion droplets;

[0063] (2) The paraffin wax emulsion droplets obtained in step (1), 150 mL of water and 5 g of γ-mercaptopropyl trimethoxysilane were mixed and reacted at 40℃ for 24 h to obtain a mixture; the mixture was mixed with 3 g of 30% mass percentage hydrogen peroxide solution and reacted at 40℃ for 24 h, then chloroform was added to dissolve the paraffin wax, and the asymmetrically modified silica particles were obtained by centrifugal washing, the particle size of the asymmetrically modified silica particles was 202 nm;

[0064] (3) Under the condition of stirring at 60℃, 1 g of sulfonated polyether ether ketone was dissolved in 50 mL of dimethyl sulfoxide, 0.1 g of asymmetrically modified silica particles obtained in step (2) was added, and after being dispersed sufficiently, it was poured into a grooved glass plate and dried to obtain an asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane, the doping amount of the asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane was 10%.

[0065] Example 2

[0066] An asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane and a preparation method thereof, the preparation method comprising the following steps:

[0067] (1) 80℃ conditions, 0.8 g of surface hydroxylated silica particles were mixed with 12 g of paraffin wax, then appropriate amount of deionized water was added, stirred at 7200 r / min for 10 min, then cooled to 20℃ by cold water bath, then washed with deionized water to obtain paraffin wax emulsion droplets;

[0068] (2) The paraffin wax emulsion droplets obtained in step (1), 150 mL of water and 5 g of γ-mercaptopropyl trimethoxysilane were mixed and reacted at 40℃ for 24 h to obtain a mixture; the mixture was mixed with 3 g of 30% mass percentage hydrogen peroxide solution and reacted at 40℃ for 24 h, then chloroform was added to dissolve the paraffin wax, and the asymmetrically modified silica particles were obtained by centrifugal washing, the particle size of the asymmetrically modified silica particles was 202 nm;

[0069] (3) Under the condition of stirring at 60℃, 1 g of sulfonated polyether ether ketone was dissolved in 50 mL of dimethyl sulfoxide, 0.1 g of asymmetrically modified silica particles obtained in step (2) was added, and after being dispersed sufficiently, it was poured into a grooved glass plate and dried to obtain an asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane, the doping amount of the asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane was 10%.

[0070] Example 3

[0071] An asymmetrically modified silica particle-doped sulfonated poly (ether ether ketone) membrane and a preparation method thereof, the preparation method comprising the following steps:

[0072] (1) 1 g of surface-hydroxylated silica particles were mixed with 10 g of paraffin wax under the condition of 80°C, and then a proper amount of deionized water was added, and stirred at a rotation speed of 6000 r / min for 10 min, and then cooled to 20°C using a cold water bath, and then washed with deionized water to obtain paraffin wax emulsion droplets;

[0073] (2) The paraffin wax emulsion droplets obtained in step (1), 150 mL of water, and 3 g of γ-mercaptopropyltrimethoxysilane were mixed and reacted at 30°C for 24 h to obtain a mixture; the mixture was mixed with 2 g of a 30% mass percentage hydrogen peroxide solution and reacted at 30°C for 24 h, and after the reaction was completed, chloroform was added to dissolve the paraffin wax, and centrifugal washing was performed to obtain the asymmetrically modified silica particles, and the particle size of the asymmetrically modified silica particles was 210 nm;

[0074] (3) 1 g of sulfonated poly (ether ether ketone) was dissolved in 50 mL of N,N-dimethylacetamide under stirring at 60°C, 0.025 g of the asymmetrically modified silica particles obtained in step (2) was added, and after being fully dispersed, poured into a grooved glass plate and dried to obtain the asymmetrically modified silica particle-doped sulfonated poly (ether ether ketone) membrane, and the doping amount of the asymmetrically modified silica particle-doped sulfonated poly (ether ether ketone) membrane was 2.5%.

[0075] Comparative Example 1

[0076] A uniformly modified silica particle-doped sulfonated poly (ether ether ketone) membrane and a preparation method thereof, the preparation method comprising the following steps:

[0077] (1) 0.8 g of surface-hydroxylated silica particles were mixed with 5 g of γ-mercaptopropyltrimethoxysilane and reacted at 40°C for 24 h to obtain a mixture; the mixture was mixed with 3 g of a 30% mass percentage hydrogen peroxide solution and reacted at 40°C for 24 h, and centrifugal washing was performed to obtain the uniformly modified silica particles;

[0078] (2) 1 g of sulfonated poly (ether ether ketone) was dissolved in 50 mL of dimethyl sulfoxide, 0.1 g of the uniformly modified silica particles obtained in step (1) was added, and after being fully dispersed, poured into a grooved glass plate and dried to obtain the uniformly modified silica particle-doped sulfonated poly (ether ether ketone) membrane.

[0079] Comparative Example 2

[0080] A surface hydroxylated silica particle doped sulfonated polyether ether ketone membrane and a preparation method thereof, the preparation method comprising: dissolving 1 g of sulfonated polyether ether ketone in 50 mL of dimethyl sulfoxide, adding 0.1 g of surface hydroxylated silica particles, and after being fully dispersed, pouring into a grooved glass plate for drying to obtain the surface hydroxylated silica particle doped sulfonated polyether ether ketone membrane.

[0081] Comparative Example 3

[0082] A surface mercapto-modified silica particle doped sulfonated polyether ether ketone membrane and a preparation method thereof, which is only different from Example 1 in that step (2) does not add hydrogen peroxide solution for oxidation reaction, and the rest of the raw materials, process parameters and steps are the same as those of Example 1.

[0083] Comparative Example 4

[0084] A uniformly modified silica particle doped sulfonated polyether ether ketone membrane and a preparation method thereof, which is only different from Example 1 in that the temperature of the reaction of paraffin emulsion droplets and γ-mercaptopropyl trimethoxysilane and the temperature of the oxidation reaction in step (2) are both 80°C, and the rest of the raw materials, process parameters and steps are the same as those of Example 1.

[0085] Comparative Example 5

[0086] An asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane and a preparation method thereof, which is only different from Example 1 in that 0.5 g of asymmetrically modified silica particles are added in step (3), and the rest of the raw materials, process parameters and steps are the same as those of Example 1.

[0087] Material characterization and performance test:

[0088] (1) Asymmetrically modified silica particle size test method: place the particles to be tested in an electron beam, and measure the particle size by observing the transmission electron image of the particles through a transmission electron microscope (JEM2001F, Japan Electron Corporation).

[0089] (2) Membrane swelling rate test method: cut the dry and clean film into equal-sized rectangular samples (3 cm x 4.5 cm), then immerse the sample in deionized water for 24 h, take out the sample and quickly wipe off the water on the flat surface of the sample with a water-absorbing paper, quickly measure and record the length after immersion. In order to reduce experimental error, 3 parallel samples of each sample are prepared for testing, and the obtained values are calculated to obtain the arithmetic mean value of the swelling rate of the membrane. The swelling rate of a single membrane can be calculated by the following formula: Wherein: L dry and L wet respectively represent the length of the membrane before and after immersion, and the test results are shown in Table 1.

[0090] (3) The proton conductivity test method of the membrane: using a resistance meter (Nanjing Damming Instrument Co., Ltd., Model DME-20) to test and record the resistance of the device with and without the tested membrane. The proton conductivity σ of the tested membrane can be calculated by the following formula: Wherein, L is the thickness of the tested membrane, cm; A is the effective area of the tested membrane, cm 2 ; R1 and R2 are the resistance of the tested membrane and the resistance without the tested membrane, respectively, Ω, and the test results are shown in Table 1;

[0091] Table 1

[0092] Swelling ratio Proton conductivity (S / cm) Example 1 10％ 0.05 Example 2 12％ 0.043 Example 3 11％ 0.04 Comparative Example 1 20％ 0.03 Comparative Example 2 15％ 0.02 Comparative Example 3 15％ 0.02 Comparative Example 4 20％ 0.04 Comparative Example 5 - -

[0093] As can be seen from Table 1, the asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane provided by the present application has a lower swelling rate and a higher proton conductivity; the uniformly modified silica particle doped sulfonated polyether ether ketone membrane provided by Comparative Example 1 does not add paraffin wax during the preparation process, and the surface of the silica particles is not asymmetrically modified, so the swelling rate of the membrane is higher; Comparative Example 2 has a poor proton conductivity of the membrane due to the lack of sulfonic acid groups grafted on the surface of the silica particles; Comparative Example 3 has a poor conductivity due to the fact that the sulfhydryl groups on the surface of the silica particles are not oxidized into sulfonic acid groups; Comparative Example 4 has a higher swelling rate of the membrane due to the fact that the reaction temperature in step (2) is too high, the paraffin wax melts during the reaction process, and the surface of the silica particles is not asymmetrically modified, so the surface of the silica particles only has sulfonic acid groups, but no hydroxyl groups; Comparative Example 5 has a significant agglomeration phenomenon due to the fact that the amount of asymmetrically modified silica particle doping is too large, so the hybrid membrane is easily broken, and data measurement cannot be performed.

[0094] (4) The energy efficiency test of the all-vanadium redox flow battery: the composition of the all-vanadium redox flow battery includes a fastening end plate, a current collector, a bipolar plate, a liquid flow frame, a carbon felt electrode and an ion exchange membrane, and is a sandwich symmetric structure with the ion exchange membrane as the center. The asymmetrically modified silica particle doped sulfonated polyether ether ketone membrane provided by Examples 1-3 and the sulfonated polyether ether ketone membrane provided by Comparative Examples 1-5 are used as the ion exchange membrane of the all-vanadium redox flow battery, and the battery test adopts an Arbin battery test system. The energy efficiency is tested at a current density of 120 mA / cm 2 , and a voltage range of 0.7-1.75 V, and the test results are shown in Table 2:

[0095] Table 2

[0096] Energy efficiency Example 1 80％ Example 2 75％ Example 3 73％ Comparative Example 1 61％ Comparative Example 2 54％ Comparative Example 3 52％ Comparative Example 4 70％ Comparative Example 5 -

[0097] As can be seen from Table 2, using the asymmetrically modified silica particle doped sulfonated poly (ether ether ketone) membrane provided by the application as the ion exchange membrane of the vanadium redox flow battery can effectively improve the energy efficiency of the flow battery. The comparative example 5 cannot be applied to the flow battery due to the easy breaking of the hybrid membrane, and thus the experimental data cannot be measured.

[0098] The applicant declares that the detailed process equipment and process flow of the application are illustrated by the above examples, but the application is not limited to the above detailed process equipment and process flow, that is, it does not mean that the application must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any improvement of the application, equivalent replacement of each raw material of the product of the application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the application.

Claims

1. A method for preparing an asymmetrically modified silica particle-doped sulfonated polyetheretherketone film, characterized in that, The preparation method includes the following steps: (1) Under heating conditions, surface hydroxylated silica particles and paraffin are mixed and then added to the first solvent and stirred, and then cooled to obtain paraffin emulsion droplets; The first solvent includes water; the heating temperature is 70-90°C; the cooling temperature is 15-25°C; (2) The paraffin emulsion droplets obtained in step (1) are mixed with a mercaptosilane coupling agent and reacted to obtain a mixture; the mixture is then mixed with hydrogen peroxide solution and subjected to an oxidation reaction to obtain the asymmetric modified silica particles; after the oxidation reaction is completed, the step of dissolving paraffin with an organic solvent is also included. (3) The asymmetric modified silica particles and sulfonated polyether ether ketone are mixed and dried to obtain the asymmetric modified silica particles doped with sulfonated polyether ether ketone film; The mass ratio of the asymmetric modified silica particles to sulfonated polyether ether ketone is (2.5-20):

100.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the surface hydroxylated silica particles to paraffin is 1:(10-20).

3. The preparation method according to claim 1, characterized in that, The stirring speed is 6000-8000 r / min.

4. The preparation method according to claim 1, characterized in that, The stirring time is 5-15 minutes.

5. The preparation method according to claim 1, characterized in that, The mercaptosilane coupling agent includes γ-mercaptopropyltrimethoxysilane and / or γ-mercaptopropyltriethoxysilane.

6. The preparation method according to claim 1, characterized in that, The mass ratio of the mercaptosilane coupling agent to the surface hydroxylated silica particles is (3-8):

1.

7. The preparation method according to claim 1, characterized in that, The reaction temperature in step (2) is 30-50 ℃.

8. The preparation method according to claim 1, characterized in that, The reaction time in step (2) is 20-28 h.

9. The preparation method according to claim 1, characterized in that, The reaction described in step (2) is carried out in the presence of a second solvent.

10. The preparation method according to claim 9, characterized in that, The second solvent includes water.

11. The preparation method according to claim 9, characterized in that, The mass ratio of the second solvent to the paraffin droplets is (10-15):

1.

12. The preparation method according to claim 1, characterized in that, The oxidation reaction is carried out at a temperature of 30-50 °C.

13. The preparation method according to claim 1, characterized in that, The oxidation reaction takes 20-28 hours.

14. The preparation method according to claim 1, characterized in that, The hydrogen peroxide solution has a mass percentage concentration of 30%.

15. The preparation method according to claim 1, characterized in that, The mass ratio of the hydrogen peroxide solution to the surface hydroxylated silica particles is (2-6):

1.

16. The preparation method according to claim 1, characterized in that, The organic solvent includes chloroform.

17. The preparation method according to claim 1, characterized in that, The asymmetric modified silica particles have a particle size of 190-210 nm.

18. The preparation method according to claim 1, characterized in that, The mixed materials in step (3) also include a third solvent.

19. The preparation method according to claim 18, characterized in that, The third solvent includes any one or a combination of at least two of N,N-dimethylformamide, dimethyl sulfoxide, or N,N-dimethylacetamide.

20. The preparation method according to claim 18, characterized in that, The ratio of the sulfonated polyether ether ketone to the third solvent is 1 g: (40-60) mL.

21. The preparation method according to claim 1, characterized in that, The mixing temperature in step (3) is 50-70℃.

22. The preparation method according to claim 1, characterized in that, The preparation method specifically includes the following steps: (1) Under heating conditions, surface hydroxylated silica particles and paraffin are mixed and then water is added and stirred, and then cooled to obtain paraffin emulsion droplets; The mass ratio of the surface hydroxylated silica particles to paraffin is 1:(10-20). The heating temperature is 70-90 ℃; The cooling temperature is 15-25℃; The stirring speed is 6000-8000 r / min; The stirring time is 5-15 minutes; (2) The paraffin emulsion droplets obtained in step (1), water and mercaptosilane coupling agent are mixed and reacted to obtain a mixture; the mixture is mixed with hydrogen peroxide solution and then subjected to an oxidation reaction; after the oxidation reaction is completed, an organic solvent is added to dissolve the paraffin to obtain the asymmetric modified silica particles. The mass ratio of the mercaptosilane coupling agent to the surface hydroxylated silica particles is (3-8):1; The reaction temperature is 30-50 ℃; The reaction time is 20-28 h; The mass ratio of water to paraffin droplets is (10-15):1; The oxidation reaction is carried out at a temperature of 30-50 °C. The oxidation reaction takes 20-28 hours. The hydrogen peroxide solution has a mass percentage concentration of 30%. The mass ratio of the hydrogen peroxide solution to the surface hydroxylated silica particles is (2-6):1; The asymmetric modified silica particles have a particle size of 190-210 nm; (3) The asymmetric modified silica particles, the third solvent and the sulfonated polyether ether ketone are mixed and dried to obtain the asymmetric modified silica particle doped sulfonated polyether ether ketone film; The mass ratio of the asymmetric modified silica particles to sulfonated polyether ether ketone is (2.5-20):100; The ratio of the sulfonated polyether ether ketone to the third solvent is 1 g: (40-60) mL; The mixing temperature is 50-70 ℃.

23. An asymmetrically modified silica particle-doped sulfonated polyetheretherketone film, characterized in that, The asymmetric modified silica particle-doped sulfonated polyether ether ketone film is prepared using the preparation method described in any one of claims 1 to 22.

24. The asymmetric modified silica particle-doped sulfonated polyetheretherketone film according to claim 23, characterized in that, The thickness of the asymmetric modified silica particle-doped sulfonated polyether ether ketone film is 70-90 μm.

25. A flow battery, characterized in that, The flow battery includes an asymmetric modified silica particle-doped sulfonated polyether ether ketone film as described in claim 23 or 24.