Proton exchange membrane for all-vanadium redox flow battery and method for manufacturing same, all-vanadium redox flow battery

Abstract

The present application provides a proton exchange membrane for an all-vanadium liquid flow battery and a method for manufacturing the same, and an all-vanadium liquid flow battery. The method includes dissolving a perfluorosulfonic acid resin in a solvent, stirring and mixing, and eliminating bubbles to form a perfluorosulfonic acid resin solution; and applying the perfluorosulfonic acid resin solution on both surfaces of a covalent organic framework reinforcement layer, and drying to obtain a proton exchange membrane; the covalent organic framework reinforcement layer is formed by covalently connecting a first precursor component and a second precursor component at a molar ratio of 1:1-1:2 at a liquid-solid interface, wherein the first precursor component is a compound containing a dialdehyde group and the second precursor component is a compound containing three amino groups, or the first precursor component is a compound containing a trialdehyde group and the second precursor component is a compound containing a diamino group. The proton exchange membrane of the present application introduces a reinforcement layer with a smaller pore size, thereby achieving good vanadium resistance, while also not affecting the conduction of hydrogen ions.

Description

Technical Field

[0001] The present application relates to the field of all-vanadium liquid flow batteries, and in particular to a proton exchange membrane for an all-vanadium liquid flow battery and a manufacturing method thereof, and an all-vanadium liquid flow battery. Background Art

[0002] Proton exchange membrane is a key component of all-vanadium liquid flow battery, which has a direct impact on the battery efficiency of all-vanadium liquid flow battery. On the one hand, the proton exchange membrane used in the all-vanadium liquid flow battery stack needs to have good vanadium resistance and high hydrogen ion conductivity, and on the other hand, it also needs to have low resistance. In addition, in order to meet the needs of all-vanadium liquid flow battery stack assembly, the proton exchange membrane needs to have a certain mechanical strength.

[0003] At present, the proton exchange membranes used in all-vanadium liquid flow batteries, such as the Nafion series membranes, are relatively expensive and their vanadium resistance is insufficient, which is not conducive to the healthy development of all-vanadium liquid flow batteries.

[0004] Therefore, there is an urgent need for a proton exchange membrane and an all-vanadium liquid flow battery with low manufacturing cost and high performance for all-vanadium liquid flow batteries. Summary of the invention

[0005] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of protection of this application.

[0006] In one aspect, the present application provides a method for manufacturing a proton exchange membrane for an all-vanadium redox flow battery, comprising dissolving a perfluorosulfonic acid resin in a solvent, stirring and mixing and eliminating bubbles to form a perfluorosulfonic acid resin solution; and coating the perfluorosulfonic acid resin solution on two surfaces of a covalent organic framework reinforcement layer, and drying to obtain the proton exchange membrane;

[0007] The covalent organic framework reinforcement layer is formed by covalently linking a first precursor component and a second precursor component at a molar ratio of 1:1-1:2 at a liquid-solid interface, wherein the first precursor component is a compound containing a dialdehyde group and the second precursor component is a compound containing three amino groups, or the first precursor component is a compound containing a trialdehyde group and the second precursor component is a compound containing a diamino group;

[0008] The compound containing a dialdehyde group is 2,5-dihydroxy-1,4-benzenedicarboxaldehyde or 1,2-bis(5-formyl-2-methylthiophen-3-yl)cyclopentene; the compound containing three amino groups is 1,3,5-tris(4-aminophenyl)-benzene or 1,3,5-tris(4-aminophenyl)-amine;

[0009] The compound containing trialdehyde groups is trimesic acid or 2-hydroxy-1,3,5-benzenetricarbaldehyde; the compound containing diamino groups is p-phenylenediamine.

[0010] In the present application, the term "perfluorosulfonic acid resin" may refer to a perfluorocarbon polymer having a sulfonic acid group, and may also include a perfluorosulfonic acid resin modified by a conventional method, as long as it can be suitable for use as a proton exchange membrane of an all-vanadium redox flow battery.

[0011] In the present application, "covalent connection at the liquid-solid interface" may mean that a compound containing a dialdehyde group and a compound containing three amino groups, or a compound containing a trialdehyde group and a compound containing a diamino group, polymerize to form a COF membrane base liquid with a ring structure. When coated on the surface of a substrate, the base liquid is adsorbed on the surface of the substrate to form a reinforcement layer.

[0012] In one embodiment, the solvent is a combination of at least three of methanol, ethanol, n-propanol, isopropanol, acetone and water.

[0013] For example, methanol and ethanol can be used as the first group of solvents, n-propanol and isopropanol can be used as the second group of solvents, and acetone and water can be used as the third group of solvents; for example, 2-6 parts by mass of the first group of solvents, 2-6 parts by mass of the second group of solvents, and 1-3 parts by mass of the third group of solvents can be used.

[0014] In one embodiment, the drying is performed at a temperature range of 50° C.-90° C. for 0.5-2 h, and then at a temperature range of 120° C.-140° C. for 0.5-1 h.

[0015] In another aspect, the present application provides a proton exchange membrane for an all-vanadium liquid flow battery, wherein the proton exchange membrane is manufactured by the above method.

[0016] In another aspect, the present application provides a proton exchange membrane for an all-vanadium redox flow battery, the proton exchange membrane comprising a first perfluorosulfonic acid resin membrane layer, a second perfluorosulfonic acid resin membrane layer, and a covalent organic framework reinforcement layer located between the first perfluorosulfonic acid resin membrane layer and the second perfluorosulfonic acid resin membrane layer;

[0017] The covalent organic framework reinforcement layer is formed by covalently linking a first precursor component and a second precursor component at a molar ratio of 1:1-1:2 at a liquid-solid interface, wherein the first precursor component is a compound containing a dialdehyde group and the second precursor component is a compound containing three amino groups, or the first precursor component is a compound containing a trialdehyde group and the second precursor component is a compound containing a diamino group;

[0018] The compound containing a dialdehyde group is 2,5-dihydroxy-1,4-benzenedicarboxaldehyde or 1,2-bis(5-formyl-2-methylthiophen-3-yl)cyclopentene; the compound containing three amino groups is 1,3,5-tris(4-aminophenyl)-benzene or 1,3,5-tris(4-aminophenyl)-amine;

[0019] The compound containing trialdehyde groups is trimesic acid or 2-hydroxy-1,3,5-benzenetricarbaldehyde; the compound containing diamino groups is p-phenylenediamine.

[0020] In one embodiment, the thickness of the proton exchange membrane is in the range of 10 μm-50 μm.

[0021] In one embodiment, the thickness of the covalent organic framework reinforcement layer is in the range of 20-100 nm.

[0022] In one embodiment, the pore size of the covalent organic framework reinforcement layer is less than 5 nm.

[0023] In yet another aspect, the present application provides an all-vanadium liquid flow battery, comprising the above-mentioned proton exchange membrane.

[0024] In the present application, the covalent organic framework reinforcement layer can be manufactured by a variety of methods. For example, the present application can adopt the following steps: dissolving the first precursor component and the second precursor component in a molar ratio of 1:1-1:2 in an organic solvent, fully mixing and reacting to obtain a COF film base liquid; coating the COF film base liquid on a substrate, heating at a temperature of about 40°C-90°C; and then rinsing with water to obtain a COF reinforcement layer with a thickness range of 20-100 nm.

[0025] The heating duration can be determined according to the amount of the COF membrane base liquid and the area of ​​the COF membrane layer.

[0026] In the present application, the substrate may be a hydrophilic substrate, which may include but is not limited to polyvinyl alcohol (PVA), polyvinyl ester (PAA), and polyvinyl amide (PAM).

[0027] The proton exchange membrane of the present application has lower cost and higher mechanical strength than homogeneous membranes of the same thickness. Due to the presence of the covalent organic framework (COF) reinforcement layer, the proton exchange membrane can have good performance while using less perfluorosulfonic acid resin.

[0028] Compared with conventional homogeneous membranes, the proton exchange membrane of the present application introduces a COF reinforcement layer with a smaller pore size, thereby achieving good vanadium resistance and not affecting the conduction of hydrogen ions. At the same time, by introducing the COF reinforcement layer, the thickness of the proton exchange membrane can be made as thin as possible while ensuring stability and conductivity.

[0029] By introducing the COF reinforcement layer, the present application can reduce the amount of resin used when preparing a proton exchange membrane of the same thickness, thereby significantly reducing the manufacturing cost.

[0030] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by implementing the present application. Other advantages of the present application can be realized and obtained by the schemes described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0032] Figure 1 is a vertical cross-sectional schematic diagram of a proton exchange membrane manufactured according to Example 1 of the present application;

[0033] Figure 2 A graph showing the battery efficiency test results according to Example 1 and Comparative Example 1 of the present application; and

[0034] Figure 3 It is a graph showing the battery efficiency test results according to Example 2 and Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present application more clear, the embodiments of the present application are described in detail below. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0036] Unless otherwise specified, the materials used in the following examples and comparative examples are commercially available.

[0037] Example 1

[0038] In this embodiment, a COF reinforcement layer is formed by covalently linking 1,2-bis(5-formyl-2-methylthiophene-3-yl)cyclopentene and 1,3,5-tri(4-aminophenyl)-amine at the liquid-solid interface. Specifically, 0.06 mmol of 1,2-bis(5-formyl-2-methylthiophene-3-yl)cyclopentene and 0.04 mmol of 1,3,5-tri(4-aminophenyl)-amine are dissolved in 100 ml of ether solvent and mixed thoroughly to obtain a COF membrane base liquid; the COF membrane base liquid is coated on a polyvinyl alcohol (PVA) substrate, heated at 50°C for 2h, and then rinsed with deionized water to obtain a COF reinforcement layer with a thickness of 30 nm;

[0039] The perfluorosulfonic acid resin is dissolved in a solvent, wherein the solvent is composed of methanol, isopropanol and acetone in a mass ratio of 3:3:1. After sufficient stirring and mixing, a perfluorosulfonic acid resin solution for film preparation is obtained, and then the solution is subjected to ultrasound for 30 minutes to remove bubbles in the perfluorosulfonic acid resin solution;

[0040] The perfluorosulfonic acid resin solution from which bubbles were removed was coated on the upper and lower surfaces of the COF reinforcement layer, and dried in an oven at 60° C. for 0.5 h, and then at 120° C. for 0.5 h, to obtain a 50 μm thick reinforced proton exchange membrane.

[0041] like Figure 1 As shown, the enhanced proton exchange membrane 1 may include a first perfluorosulfonic acid resin membrane layer 10, a second perfluorosulfonic acid resin membrane layer 30, and a covalent organic framework reinforcement layer 20 located between the first perfluorosulfonic acid resin membrane layer 10 and the second perfluorosulfonic acid resin membrane layer 30. The first perfluorosulfonic acid resin membrane layer 10 and the second perfluorosulfonic acid resin membrane layer 30 are the same, or are made of the same material and process.

[0042] However, in other embodiments, the first perfluorosulfonic acid resin film layer and the second perfluorosulfonic acid resin film layer may also be prepared by different materials or different processes to meet specific desired performance requirements.

[0043] Example 2

[0044] In this embodiment, a COF reinforcement layer is formed by covalently linking 2,5-dihydroxy-1,4-benzenedicaldehyde and 1,3,5-tris(4-aminophenyl)-benzene at the liquid-solid interface. Specifically, 0.08 mmol of 2,5-dihydroxy-1,4-benzenedicaldehyde and 0.06 mmol of 1,3,5-tris(4-aminophenyl)-benzene are dissolved in 50 ml of ethanol solvent and mixed thoroughly to obtain a COF membrane base liquid; the COF membrane base liquid is coated on a polyvinyl alcohol (PVA) substrate, heated at 40°C for 2.5 hours, and then rinsed with deionized water to obtain a COF reinforcement layer with a thickness of 30 nm;

[0045] The perfluorosulfonic acid resin is dissolved in a solvent, wherein the composition of the solvent is ethanol, n-propanol and water, and the mass ratio is 4:4:1.5. After sufficient stirring and mixing, a perfluorosulfonic acid resin solution for film preparation is obtained, and then the solution is placed in an ultrasonic state for 30 minutes to remove bubbles in the resin solution;

[0046] The perfluorosulfonic acid resin solution with bubbles removed was coated on the upper and lower surfaces of the COF reinforcement layer, dried in an oven at 55°C for 1 hour, and then dried at 130°C for 0.5 hour to obtain a 50 μm thick reinforced proton exchange membrane.

[0047] Comparative Example 1

[0048] The difference between this comparative example and Example 1 is that no COF reinforcement layer is used, and only the prepared perfluorosulfonic acid resin solution is coated on the substrate, and then placed in an oven to dry at 60°C for 0.5h, and then dried at 120°C for 0.5h, to obtain a homogeneous film of 50μm with the same thickness as Example 1.

[0049] Comparative Example 2

[0050] The difference between this comparative example and Example 2 is that no COF reinforcement layer is used, and only the prepared perfluorosulfonic acid resin solution is coated on the substrate, and then placed in an oven to dry at 55°C for 1 hour, and then dried at 130°C for 0.5 hour, to obtain a 50 μm homogeneous film with the same thickness as Example 2.

[0051] Performance Testing

[0052] 1. Physical properties test of membrane

[0053] The physical properties of the proton exchange membranes prepared in the embodiments and comparative examples were tested, including the tensile strength and elongation at break of each proton exchange membrane according to the standard GB / T1040-2006; the water absorption rate, dimensional change rate and membrane surface resistance of each proton exchange membrane were tested according to the standard NB / T 42080-2023. The results are shown in Tables 1 and 2.

[0054] Table 1

[0055]

[0056] Table 2

[0057]

[0058] According to the results in Table 1 and Table 2, the tensile strength and elongation at break of Examples 1 and 2 are higher than those of the comparative example, and at the same time, they have lower water absorption, swelling rate and membrane surface resistance, indicating that the COF reinforcement layer effectively improves the basic physical properties of the proton exchange membrane.

[0059] 2. Battery efficiency test

[0060] The proton exchange membranes prepared in the embodiments and comparative examples were assembled in the all-vanadium liquid flow cell and charged and discharged at a constant current of 4A. The effective area of ​​the cell reaction was 25cm 2 1.8M vanadium electrolyte was used for both positive and negative electrodes, with a dosage of 1L. The initial valence was 3.5. 300 charge and discharge cycles were performed. The charge and discharge efficiency curves are shown as follows: Figure 2 and Figure 3 shown. Figure 2 is a graph showing the battery efficiency test results of Example 1 and Comparative Example 1. Figure 3 is a graph showing the battery efficiency test results of Example 2 and Comparative Example 2.

[0061] according to Figure 2 and Figure 3 It can be seen from the results that the proton exchange membranes of Example 1 and Example 2 exhibit higher Coulomb efficiency, indicating that the COF enhanced layer effectively improves the vanadium resistance of the proton exchange membrane; in addition, the higher voltage efficiency also shows that the presence of the COF enhanced layer not only does not affect the conduction of hydrogen ions, but is more conducive to the conduction of hydrogen ions.

[0062] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for manufacturing a proton exchange membrane for an all-vanadium redox flow battery, characterized in that: The method comprises dissolving a perfluorosulfonic acid resin in a solvent, stirring and mixing and eliminating bubbles to form a perfluorosulfonic acid resin solution; and coating the perfluorosulfonic acid resin solution on two surfaces of a covalent organic framework reinforcement layer, and drying to obtain the proton exchange membrane; The covalent organic framework reinforcement layer is manufactured by the following method: dissolving a first precursor component and a second precursor component in a molar ratio of 1:1-1:2 in an organic solvent, mixing and reacting to obtain a COF membrane base liquid; coating the COF membrane base liquid on a hydrophilic substrate, heating at a temperature of 40°C-90°C; and then rinsing with water; The first precursor component is 1,2-bis(5-formyl-2-methylthiophen-3-yl)cyclopentene and the second precursor component is 1,3,5-tris(4-aminophenyl)-amine, or the first precursor component is 2,5-dihydroxy-1,4-benzenedicarbaldehyde and the second precursor component is 1,3,5-tris(4-aminophenyl)-benzene; wherein the organic solvent is ethanol or ether; The hydrophilic substrate is polyvinyl alcohol or polyvinyl ester; The thickness of the covalent organic framework reinforcement layer is in the range of 20-100 nm.

2. The method according to claim 1, characterized in that The solvent is a combination of at least three of methanol, ethanol, n-propanol, isopropanol, acetone and water.

3. The method according to claim 1, characterized in that The drying is performed at a temperature range of 50° C. to 90° C. for 0.5 to 2 h, and then at a temperature range of 120° C. to 140° C. for 0.5 to 1 h.

4. The method according to claim 1, characterized in that: The solvent includes 2-6 parts by mass of a first group of solvents, 2-6 parts by mass of a second group of solvents and 1-3 parts by mass of a third group of solvents, wherein the first group of solvents includes methanol and ethanol, the second group of solvents includes n-propanol and isopropanol, and the third group of solvents includes acetone and water.

5. A proton exchange membrane for an all-vanadium liquid flow battery, characterized in that: The proton exchange membrane is manufactured by the method according to any one of claims 1-4.

6. A proton exchange membrane for an all-vanadium liquid flow battery, characterized in that: The proton exchange membrane comprises a first perfluorosulfonic acid resin membrane layer, a second perfluorosulfonic acid resin membrane layer, and a covalent organic framework reinforcement layer located between the first perfluorosulfonic acid resin membrane layer and the second perfluorosulfonic acid resin membrane layer; The covalent organic framework reinforcement layer is manufactured by the following method: dissolving a first precursor component and a second precursor component in a molar ratio of 1:1-1:2 in an organic solvent, mixing and reacting to obtain a COF membrane base liquid; coating the COF membrane base liquid on a hydrophilic substrate, heating at a temperature of 40°C-90°C; and then rinsing with water; The first precursor component is 1,2-bis(5-formyl-2-methylthiophen-3-yl)cyclopentene and the second precursor component is 1,3,5-tris(4-aminophenyl)-amine, or the first precursor component is 2,5-dihydroxy-1,4-benzenedicarbaldehyde and the second precursor component is 1,3,5-tris(4-aminophenyl)-benzene; wherein the organic solvent is ethanol or ether; The hydrophilic substrate is polyvinyl alcohol or polyvinyl ester; The thickness of the covalent organic framework reinforcement layer is in the range of 20-100 nm.

7. The proton exchange membrane according to claim 6, characterized in that The thickness of the proton exchange membrane is in the range of 10 μm to 50 μm.

8. The proton exchange membrane according to claim 6, characterized in that: The solvent includes 2-6 parts by mass of a first group of solvents, 2-6 parts by mass of a second group of solvents and 1-3 parts by mass of a third group of solvents, wherein the first group of solvents includes methanol and ethanol, the second group of solvents includes n-propanol and isopropanol, and the third group of solvents includes acetone and water.

9. The proton exchange membrane according to any one of claims 6 to 8, characterized in that The pore size of the covalent organic framework reinforcement layer is less than 5 nm.

10. An all-vanadium liquid flow battery, characterized in that: The all-vanadium liquid flow battery comprises the proton exchange membrane according to claim 5, or comprises the proton exchange membrane according to any one of claims 6-9.

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