CN110957514A - Strong hydrophobic ion exchange membrane and preparation method and application thereof - Google Patents
Strong hydrophobic ion exchange membrane and preparation method and application thereof Download PDFInfo
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- CN110957514A CN110957514A CN201911226763.7A CN201911226763A CN110957514A CN 110957514 A CN110957514 A CN 110957514A CN 201911226763 A CN201911226763 A CN 201911226763A CN 110957514 A CN110957514 A CN 110957514A
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- ion exchange
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- acid resin
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/18—Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
- H01M8/184—Regeneration by electrochemical means
- H01M8/188—Regeneration by electrochemical means by recharging of redox couples containing fluids; Redox flow type batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
- H01M8/1018—Polymeric electrolyte materials
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
- H01M8/1018—Polymeric electrolyte materials
- H01M8/1069—Polymeric electrolyte materials characterised by the manufacturing processes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Abstract
A strong hydrophobic ion exchange membrane and a preparation method and application thereof belong to the field of polymer membrane materials, and the key point is that hydrophobic fumed silica is added into a perfluorinated sulfonic acid resin solution under the action of a siloxane stabilizer, and the ion exchange membrane is prepared by a tape casting method. The ion exchange membrane has the effect that the ion exchange membrane has strong apparent hydrophobicity, and water drops can freely roll on the surface of the membrane to present a typical lotus effect. By introducing the membrane with strong hydrophobicity into the all-vanadium flow battery system, the migration rate of water and vanadium ions through the ion exchange membrane can be greatly reduced, the coulomb efficiency of the battery is improved, and the swelling ratio of the ion exchange membrane is reduced.
Description
Technical Field
The invention belongs to the field of polymer membrane materials, and particularly relates to a strong-hydrophobicity ion exchange membrane as well as a preparation method and application thereof.
Background
The ion exchange membrane is a key component of the all-vanadium redox flow battery system, and mainly has the functions of isolating positive and negative electrolytes and conducting ions to enable the battery to form a complete closed loop. So far, ion exchange membranes used in all-vanadium flow battery systems are mainly perfluorosulfonic acid ion exchange membranes, and because raw materials for producing the membranes are expensive and the synthesis technical route is complex, the price is high, so that a great number of researchers try to re-cast ion exchange membranes by dissolving damaged waste membranes, leftover material membranes and used ion exchange membranes in a specific solvent after being treated by a certain means to prepare a perfluorosulfonic acid resin solution. Meanwhile, the perfluorosulfonic acid ion exchange membrane is not specially designed for an all-vanadium flow battery system, so that high vanadium mobility and water mobility are main defects of the perfluorosulfonic acid ion exchange membrane besides high price. Therefore, the preparation of the ion exchange membrane with high vanadium resistance effect and low water mobility by the perfluorinated sulfonic acid resin solution becomes a main direction.
According to the invention, the hydrophobic fumed silica is introduced into a perfluorinated sulfonic acid resin ion exchange membrane system, so that the apparent hydrophobicity of the ion exchange membrane is greatly improved, the water mobility is greatly reduced, the membrane swelling rate is reduced, the vanadium resistance effect is excellent, and the coulomb efficiency of the battery is improved.
Disclosure of Invention
In order to make up for the defects of the prior art, the invention provides a simple and convenient preparation method of the ion exchange membrane with strong hydrophobicity.
The technical scheme of the invention is that the preparation method of the strong hydrophobic ion exchange membrane comprises the following steps:
(1) dispersing hydrophobic fumed silica in a perfluorinated sulfonic acid resin solution, adding a certain amount of siloxane as a stabilizer, and strongly stirring until the system is completely transparent;
(2) spreading the solution obtained in the step (1) on a horizontal glass plate, and preparing an ion exchange membrane by a tape casting method;
(3) soaking the ion exchange membrane in the step (2) in dilute sulfuric acid overnight, and then washing with deionized water to obtain the strong hydrophobic ion exchange membrane.
The concentration of the perfluorinated sulfonic acid resin solution is 5-20 wt%; the solvent of the perfluorinated sulfonic acid resin solution is one of dimethyl sulfoxide, N '-dimethylformamide and N, N' -dimethylacetamide; the mass of the hydrophobic fumed silica is 2-8 wt% of the content of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin solution; the siloxane stabilizer has the structure CnH2n-1-Si(OCH3)3Or CnH2n-1-Si(OCH2CH3)3Wherein n is 2,3 or 4, and the mass ratio of the dosage of the hydrophobic fumed silica to the hydrophobic fumed silica is (0.5-1.5): 1.
preferably, the hydrophobic fumed silica is HB series hydrophobic fumed silica produced by Guangzhou Gibby scientific and technical industry Co;
preferably, the HB series hydrophobic fumed silica is HB-215.
The fumed silica is greatly different from the traditional silica and the nanometer particles thereof, the traditional silica and the nanometer particles thereof are only special in appearance and size, but the molecular structure of the silica is not changed; the fumed silica, particularly the hydrophobic fumed silica, is prepared by hydrolyzing chlorosilane in oxyhydrogen flame at high temperature (also called white carbon black) and connecting groups such as non-hydrolyzed methyl and the like on the surface, and the hydrophilicity of the fumed silica can be greatly reduced.
The siloxane used as a stabilizer can improve the solubility and stability of hydrophobic fumed silica in a perfluorosulfonic acid resin solution, and is favorable for forming a uniform solution.
The function of soaking the dilute sulfuric acid overnight is to fully hydrolyze siloxane remained on the surface of the membrane under acidic conditions, and the concentration of the siloxane is not specifically required.
Another object of the present invention is to protect the strongly hydrophobic ion exchange membrane prepared by the above method.
The third purpose of the invention is to protect the application of the strong hydrophobic ion exchange membrane prepared by the method in the flow battery.
The fourth purpose of the invention is to protect the application of the strong hydrophobic ion exchange membrane prepared by the method in the all-vanadium redox flow battery.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention provides a novel method for preparing a strong-hydrophobicity ion exchange membrane by using a perfluorinated sulfonic acid resin solution, which has the advantages of simple preparation process, low price of used auxiliary materials and suitability for large-scale production;
(2) the ion exchange membrane with strong hydrophobicity prepared by the invention has strong apparent hydrophobicity, and water drops and sulfuric acid system vanadium electrolyte liquid drops can freely roll on the surface of the membrane, thus presenting a typical 'lotus effect';
(3) the membrane with strong hydrophobicity is introduced into an all-vanadium flow battery system, so that the migration rate of water and vanadium ions through an ion exchange membrane can be greatly reduced, the coulomb efficiency of the battery is improved, and the swelling rate of the ion exchange membrane is reduced.
Detailed Description
The invention is described in more detail below with reference to specific examples, without limiting the scope of the invention. Unless otherwise specified, the experimental method used in the present invention is a conventional method, and the experimental equipment, materials, reagents, etc. used therein may be purchased from chemical companies or suppliers.
The contact angle test instrument used in the invention is an OCA50AF full-automatic optical contact angle tester produced by Germany dataphysics company, and in the test result, the larger the contact angle is, the better the apparent hydrophobicity is.
The swelling ratio (or called size change ratio) of the ion exchange membrane is tested by referring to a size change ratio test method in the energy industry standard NB/T42080-2016 (ion conductive membrane test method for all-vanadium flow batteries) of the people's republic of China.
The performance test conditions of the all-vanadium redox flow battery with the ion exchange membrane are as follows: at a current density of 80mA/cm2Performing charge-discharge experiment under the condition of charging to 1.55V and discharging to 1.00V, using Beijing crystal dragonThe graphite carbon felt produced by the Tec technology Limited company is used as a reaction electrode, and the effective working area of the electrode is 48cm2The positive and negative electrolytes are VO2+/VO2 +And V2+/V3+The battery operating temperature of the sulfuric acid solution of (1) was 37 ℃.
The self-discharge time test of the battery is to disconnect an external liquid path from the battery when the battery is charged to 1.55V, and reduce the voltage of the battery to 1.20V, and the self-discharge of the battery is mainly caused by the migration of vanadium ions through an ionic membrane, so the vanadium resistance of the ionic exchange membrane can be judged through self-discharge, namely the longer the self-discharge time is, the better the vanadium resistance effect is.
Example 1
Dispersing 5g of hydrophobic fumed silica (HB-215) and 5g of vinyl triethoxysilane in 1000g of dimethyl sulfoxide solution (with the concentration of 10 wt%) of perfluorosulfonic acid resin, and dispersing by using a dispersing machine until the solution is a uniform and transparent system to form a casting solution; then spreading the obtained casting film liquid on the surface of a smooth glass plate, and preparing an ion exchange membrane with the thickness of 50um by a casting method; and finally, soaking the prepared ion exchange membrane in 2mol/L dilute sulfuric acid overnight, taking out and washing the surface with deionized water to prepare the strong-hydrophobicity ion exchange membrane.
In this example, the mass of the hydrophobic fumed silica was 5% of the mass of the perfluorosulfonic acid resin, and the mass ratio of the siloxane to the hydrophobic fumed silica was 1: 1.
example 2
The concentration of the dimethyl sulfoxide solution of the perfluorosulfonic acid resin is changed from 10 wt% to 5 wt%, and the dosage of other substances is the same as the proportion of the embodiment 1, so that the strong hydrophobic ion exchange membrane with the thickness of 50um is prepared.
Example 3
The concentration of the dimethyl sulfoxide solution of the perfluorosulfonic acid resin is changed from 10 wt% to 20 wt%, and the dosage of other substances is the same as the proportion of the embodiment 1, so that the strong hydrophobic ion exchange membrane with the thickness of 50um is prepared.
Example 4
Dispersing 2g of hydrophobic fumed silica (HB-215) and 1g of vinyl triethoxysilane in 1000g of dimethyl sulfoxide solution (with the concentration of 10 wt%) of perfluorosulfonic acid resin, and dispersing by using a dispersing machine until the solution is a uniform and transparent system to form a casting solution; then spreading the obtained casting film liquid on the surface of a smooth glass plate, and preparing an ion exchange membrane with the thickness of 50um by a casting method; and finally, soaking the prepared ion exchange membrane in 2mol/L dilute sulfuric acid overnight, taking out and washing the surface with deionized water to prepare the strong-hydrophobicity ion exchange membrane.
In this example, the mass of the hydrophobic fumed silica was 2% of the mass of the perfluorosulfonic acid resin, and the mass ratio of the siloxane to the hydrophobic fumed silica was 0.5: 1.
example 5
Dispersing 8g of hydrophobic fumed silica (HB-215) and 12g of vinyl triethoxysilane in 1000g of dimethyl sulfoxide solution (with the concentration of 10 wt%) of perfluorosulfonic acid resin, and dispersing by using a dispersing machine until the solution is a uniform and transparent system to form a casting solution; then spreading the obtained casting film liquid on the surface of a smooth glass plate, and preparing an ion exchange membrane with the thickness of 50um by a casting method; and finally, soaking the prepared ion exchange membrane in 2mol/L dilute sulfuric acid overnight, taking out and washing the surface with deionized water to prepare the strong-hydrophobicity ion exchange membrane.
In this example, the mass of the hydrophobic fumed silica was 8% of the mass of the perfluorosulfonic acid resin, and the mass ratio of the siloxane to the hydrophobic fumed silica was 1.5: 1.
example 6
The stabilizer was changed from vinyltriethoxysilane to isopropyltrimethoxysilane, and the solvent for the perfluorosulfonic acid resin solution was changed from dimethyl sulfoxide to N, N' -dimethylformamide, and the other steps were the same as in example 1.
Example 7
The stabilizer was changed from vinyltriethoxysilane to isobutyltriethoxysilane, and the solvent for the perfluorosulfonic acid resin solution was changed from dimethylsulfoxide to N, N' -dimethylacetamide, otherwise the same procedure as in example 1 was repeated.
Comparative example 1
An ion exchange membrane of 50um was prepared without adding hydrophobic fumed silica to the system, and the other conditions were kept the same as in example 1.
TABLE 1 Performance data for ion exchange membranes prepared in examples 1-7 and comparative example 1
As can be seen from the data of examples and comparative examples in table 1, the contact angle of water drops on the ion exchange membrane doped with hydrophobic fumed silica is significantly increased, the swelling ratio is significantly decreased, the coulombic efficiency in the battery performance is significantly increased, and the self-discharge time is significantly prolonged, which shows that the hydrophobic property and vanadium-blocking property of the ion exchange membrane are significantly improved by the introduction of the hydrophobic fumed silica, and the more the amount of the hydrophobic fumed silica doped in the perfluorosulfonic acid resin is, the more the hydrophobic effect is apparent from examples 1,4 and 5. As can be seen from examples 1,2 and 3, the hydrophobicity of the membrane surface is only related to the proportion of the hydrophobic fumed silica added into the membrane, and the performances of the hydrophobic fumed silica are similar under the same proportion; it can be seen from examples 1,6 and 7 that similar effects can be achieved with different stabilizers when perfluorosulfonic acid resin solutions of different solvents are used.
The above description is only for the purpose of creating a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can substitute or change the technical solution and the inventive concept of the present invention within the technical scope of the present invention.
Claims (8)
1. The preparation method of the strong hydrophobic ion exchange membrane is characterized by comprising the following steps:
s1, dispersing hydrophobic fumed silica in a perfluorinated sulfonic acid resin solution to obtain a membrane casting solution;
s2, the obtained casting film liquid is paved on the surface of a smooth glass plate, and the ion exchange membrane is prepared through a tape casting method.
2. The method of claim 1, further comprising the step of:
s3, soaking the prepared ion exchange membrane in dilute sulfuric acid overnight, and then washing with deionized water to obtain the ion exchange membrane with strong hydrophobicity.
3. The method according to claim 1 or 2, wherein in step S1, after the hydrophobic fumed silica is dispersed in the perfluorosulfonic acid resin solution, siloxane is added to the solution as a stabilizer, and the mixture is stirred until the system is completely transparent to obtain the casting solution.
4. The method according to claim 3, wherein the solvent of the perfluorosulfonic acid resin solution is one of dimethyl sulfoxide, N '-dimethylformamide and N, N' -dimethylacetamide, the concentration of the perfluorosulfonic acid resin solution is 5 to 20 wt%, the mass of the hydrophobic fumed silica is 2 to 8 wt% of the content of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin solution, and the ratio of the amount of the siloxane to the mass of the hydrophobic fumed silica is (0.5 to 1.5): 1.
5. the method of claim 2, wherein the silicone stabilizer has the structure CnH2n-1-Si(OCH3)3Or CnH2n-1-Si(OCH2CH3)3Wherein n is 2,3 or 4.
6. A strongly hydrophobic ion exchange membrane prepared by the process of any of claims 1 to 5.
7. The use of the strongly hydrophobic ion exchange membrane of claim 6 in a flow battery.
8. The application of the strongly hydrophobic ion exchange membrane of claim 6 in improving vanadium resistance in an all-vanadium flow battery.
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