阅读说明：本技术 一种复合离子交换膜及其制备方法和应用 (Composite ion exchange membrane and preparation method and application thereof ) 是由 张瑜 喻军 田晶 余谣 张传升 赵剑 韩青树 于 2019-11-21 设计创作，主要内容包括：本发明提供一种复合离子交换膜,其原料以重量份数计,包括以下组分：磺化聚醚砜80～98份；三苯胺1～10份；聚四氟乙烯1～10份。通过采用磺化聚醚砜为主体材料,并采用三苯胺和聚四氟乙烯作为掺杂剂,使得最终制得的复合离子交换膜具有较好的离子选择性和化学稳定性。(The invention provides a composite ion exchange membrane which comprises the following raw materials in parts by weight: 80-98 parts of sulfonated polyether sulfone; 1-10 parts of triphenylamine; 1-10 parts of polytetrafluoroethylene. By adopting sulfonated polyether sulfone as a main material and adopting triphenylamine and polytetrafluoroethylene as doping agents, the finally prepared composite ion exchange membrane has better ion selectivity and chemical stability.)

1. The composite ion exchange membrane comprises the following raw materials in parts by weight:

80-98 parts of sulfonated polyether sulfone;

1-10 parts of triphenylamine;

1-10 parts of polytetrafluoroethylene.

2. The composite ion exchange membrane according to claim 1, wherein the weight part ratio of the triethylamine to the polytetrafluoroethylene is 1:8-8:1, preferably 1:1-8: 1.

3. The composite ion-exchange membrane according to claim 1 or 2, wherein the starting material further comprises an organic solvent, preferably the organic solvent comprises C₁-C₅Amide, more preferably said C₁-C₅The amide is N-methylacetamide; preferably, the organic solvent is 400 to 1000 parts by weight, preferably 400 to 800 parts by weight.

4. The composite ion-exchange membrane according to any one of claims 1 to 3, wherein the sulfonated polyethersulfone has a degree of sulfonation of 40% to 60%, preferably 43% to 58%; and/or the molecular weight is 50000-90000, preferably 60000-70000; and/or a particle size of 1 μm to 100 μm, preferably 50 μm to 100 μm; and/or

The molecular weight of the polytetrafluoroethylene is 5000-.

5. A method of preparing the composite ion exchange membrane of any one of claims 1-4 comprising:

a) providing a mixed solution comprising the triphenylamine, the polytetrafluoroethylene, and the sulfonated polyethersulfone;

b) and carrying out tape casting film forming treatment on the mixed solution to obtain the composite ion exchange membrane.

6. The method according to claim 5, wherein the mixed solution contains an organic solvent, preferably wherein the organic solvent comprises C₁-C₅Amide, more preferably said C₁-C₅The amide is N-methylacetamide.

7. The preparation method according to claim 5 or 6, wherein in the step a), the triphenylamine and the polytetrafluoroethylene are added into the solution containing the sulfonated polyethersulfone, and then the solution is stirred at a temperature of 20-25 ℃ for 5-10 h at a rotation speed of 50-100 r/min, so as to obtain the mixed solution.

8. A production method according to any one of claims 5 to 7, wherein said casting film-forming process includes a step of casting and removing a solvent;

preferably, the step of tape casting includes pouring the mixed solution into a mold, preferably, the mold is made of stainless steel; and/or

The step of removing the solvent comprises: standing for 1-10 h at the temperature of 85-95 ℃, and then standing for 5-15 h at the temperature of 95-105 ℃.

9. Use of the composite ion exchange membrane according to any one of claims 1 to 4 or the composite ion exchange membrane prepared by the preparation method according to any one of claims 5 to 8 in the field of vanadium batteries, in particular in the field of vanadium battery diaphragms.

10. Use according to claim 9, wherein the composite ion-exchange membrane is stored in deionized water before use in the field of vanadium batteries, in particular in the field of vanadium battery separators.

Technical Field

The invention relates to the technical field of new energy storage, in particular to a composite ion exchange membrane and a preparation method and application thereof.

Background

The shortage of fossil energy and environmental pollution are two major problems that people face at present and need to solve urgently, and the development and utilization of new energy such as solar energy, geothermal energy, wind energy and the like become hot spots in the current times. The use of these renewable energy sources requires a large-scale energy storage device to convert them into a stable, sustainable energy source.

The all-vanadium redox flow battery is a large-scale energy storage system, and has the advantages of safety, flexible design, independent energy and power, long service life and the like compared with other batteries. The key materials of the all-vanadium redox flow battery mainly comprise an electrode, a diaphragm and an electrolyte. The diaphragm is used for separating positive electrolyte from negative electrolyte and allowing charge carriers to pass through the diaphragm to complete the internal circulation of the circuit. The diaphragm has the following characteristics: high ionic conductivity, low vanadium ion permeability, strong mechanical property and the like. The porous membrane can realize ion transmission without ion exchange groups, so that the damage to a polymer framework can be avoided, and the porous membrane has good stability, so that the porous membrane has received wide attention in all-vanadium redox flow batteries. The diaphragm has the action principle that the aperture of the diaphragm is between that of hydrogen ions and vanadium ions by controlling the aperture of the diaphragm, so that the circulation of an internal circuit and an external circuit can be realized through protons, and the penetration of the vanadium ions can be effectively prevented.

The ion exchange membranes mainly used at present are Nafion series ion exchange membranes produced by DuPont. However, the Nafion series ion exchange membranes mainly have two obvious problems of high manufacturing cost and poor corrosion resistance.

In summary, it is necessary to design and prepare an ion exchange membrane for a vanadium redox battery with low manufacturing cost and good chemical stability.

Disclosure of Invention

In view of the problems in the prior art, an object of the present invention is to provide a composite ion exchange membrane, wherein sulfonated polyethersulfone is used as a host material, and triphenylamine and polytetrafluoroethylene are used as dopants, so that the finally prepared composite ion exchange membrane has good ion selectivity and chemical stability.

The second purpose of the invention is to provide a preparation method of the composite ion exchange membrane corresponding to the first purpose.

The invention also aims to provide application of the composite ion exchange membrane corresponding to the aim.

In order to achieve one of the above purposes, the technical scheme adopted by the invention is as follows:

the composite ion exchange membrane comprises the following raw materials in parts by weight:

80-98 parts of sulfonated polyether sulfone;

1-10 parts of triphenylamine;

1-10 parts of polytetrafluoroethylene.

According to the invention, preferably, the raw materials comprise the following components in parts by weight:

85-95 parts of sulfonated polyether sulfone;

5-10 parts of triphenylamine;

1-5 parts of polytetrafluoroethylene.

The inventor of the present application found in research that triphenylamine and polytetrafluoroethylene have a synergistic effect. Especially, when the content of triphenylamine and polytetrafluoroethylene is within the above range, the synergistic effect is more remarkable. The two are mutually matched, so that the conductivity of the composite ion exchange membrane can be obviously increased, and the vanadium resistance, mechanical strength, chemical stability and mechanical stability of the composite ion exchange membrane are improved. In addition, triphenylamine and polytetrafluoroethylene are used in a matched mode, a better ion selection effect can be obtained, and the coulombic efficiency and the energy efficiency of the assembled battery are influenced finally.

In some preferred embodiments of the invention, the weight parts ratio of the triethylamine to the polytetrafluoroethylene is from 1:8 to 8:1, preferably from 1:1 to 8: 1.

According to the invention, the weight parts ratio of the triethylamine to the polytetrafluoroethylene can be enumerated as 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, and any value therebetween.

In some preferred embodiments of the present invention, the starting material further comprises an organic solvent, preferably the organic solvent comprises C₁-C₅Amide, more preferably said C₁-C₅The amide is N-methylacetamide; preferably, the organic solvent is 400 to 1000 parts by weight, preferably 400 to 800 parts by weight.

According to the invention, N-methylacetamide is used as a solvent, and the method has at least the following beneficial effects:

firstly, the volatilization process of N-methylacetamide is stable, and a high-quality film without holes is easily formed.

Secondly, the film-forming solution formed by using N-methylacetamide as a solvent is dense and viscous, cannot be influenced by external mechanical vibration or slight horizontal change, and is easy to form a uniform film.

Thirdly, the N-methylacetamide volatilizes more completely and has less residue.

In some preferred embodiments of the present invention, the sulfonated polyethersulfones have a degree of sulfonation ranging from 40% to 60%, preferably from 43% to 58%.

According to the invention, the degree of sulfonation of the sulfonated polyethersulfones may be listed as 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, and 60% and any value therebetween.

In some preferred embodiments of the present invention, the sulfonated polyethersulfone has a molecular weight of 50000 to 90000, preferably 60000 to 70000.

According to the invention, the molecular weight of the sulfonated polyethersulfones may be enumerated as 50000, 55000, 60000, 65000, 70000, 75000, 80000, 85000, 90000 and any value therebetween.

In some preferred embodiments of the present invention, the sulfonated polyethersulfones have a particle size of 1 to 100 microns, preferably 50 to 100 microns.

According to the invention, the particle size of the sulfonated polyether sulfone is specified as 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm and any value therebetween.

According to the present invention, the sulfonated polyethersulfones are commercially available or may be prepared by a process comprising the steps of:

mixing the polyethersulfone with concentrated sulfuric acid, and sulfonating at 35-65 ℃, preferably 45-55 ℃ for 1-10 h, preferably 4-6 h to obtain the sulfonated polyethersulfone.

In some preferred embodiments of the invention, the molecular weight of the polytetrafluoroethylene is 5000-.

According to the invention, the molecular weight of the polytetrafluoroethylene can be listed as 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, 10000 and any value in between.

In order to achieve the second purpose, the invention adopts the following technical scheme:

the preparation method of the composite ion exchange membrane comprises the following steps:

a) providing a mixed solution comprising the triphenylamine, the polytetrafluoroethylene, and the sulfonated polyethersulfone;

b) and carrying out tape casting film forming treatment on the mixed solution to obtain the composite ion exchange membrane.

In some preferred embodiments of the present invention, the mixed solution containing the organic solvent comprises an organic solvent, preferably the organic solvent comprises C₁-C₅Amide, more preferably said C₁-C₅The amide is N-methylacetamide.

In some preferred embodiments of the present invention, in the step a), the triphenylamine and the polytetrafluoroethylene are added into the solution containing the sulfonated polyethersulfone, and then the solution is stirred at a temperature of 20 ℃ to 25 ℃ for 5h to 10h at a rotation speed of 50r/min to 100r/min, so as to obtain the mixed solution.

In some preferred embodiments of the present invention, the cast film-forming process includes the steps of casting and removing a solvent;

preferably, the step of tape casting includes pouring the mixed solution into a mold, preferably, the mold is made of stainless steel; and/or

The step of removing the solvent comprises: standing for 1-10 h at the temperature of 85-95 ℃, and then standing for 5-15 h at the temperature of 95-105 ℃.

In order to achieve the third purpose, the invention adopts the following technical scheme:

the composite ion exchange membrane or the composite ion exchange membrane prepared by the preparation method is applied to the field of vanadium batteries, particularly to the field of vanadium battery diaphragms.

In some preferred embodiments of the invention, the composite ion-exchange membrane is stored in deionized water prior to use in the vanadium battery field, particularly the vanadium battery separator field.

The composite ion exchange membrane prepared by the preparation method provided by the invention has the ion exchange capacity of 1.33 mmol-g in a specific embodiment^-1The tensile strength can reach 45.88Mpa, the water absorption can reach 47.8 percent, and the conductivity can reach 0.058S-cm^-1The vanadium ion permeability can reach 1.76 multiplied by 10^-7 cm²Min-1, ion selectivity up to S.min.cm^-3The coulombic efficiency can reach 95.6%, the voltage efficiency can reach 83.1%, and the energy efficiency can reach 79.4%.

Detailed Description

The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to the following description.

The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

The performance of the prepared composite ion exchange membrane is tested, and the specific test method comprises the following steps:

(1) electrochemical performance test

And cutting the prepared composite ion exchange membrane into a certain size, assembling the cut composite ion exchange membrane in a battery model, and carrying out electrochemical performance test.

(2) Ion exchange Capacity test

The ion exchange capacity of the prepared composite ion exchange membrane is determined by a titration method. Drying the acid film, and soaking in 0.1mol/L NaCl solution for 24H until H⁺、Na⁺After sufficient exchange, the pH was adjusted to 7 by titration with 0.005mol/L NaOH solution. The formula is as follows:

(3) tensile strength

The mechanical properties of the wet film were tested by an electronic universal tester, with a drawing speed of 5 mm/min.

(4) Water absorption rate

Soaking the composite film in deionized water for 24h, taking out, wiping the surface with water, weighing Ws, placing the film in a drying oven, drying at 100 ℃ for 10h, taking out, weighing Wdry film weight Wdry, and calculating the water absorption rate according to the mass of the wet film and the dry film. The formula is as follows:

(5) degree of sulfonation

The degree of sulfonation is calculated from the ion exchange capacity, and the formula is as follows:

example 1

Firstly, 90 parts of sulfonated polyether sulfone (with a sulfonation degree of 50%, a molecular weight of 60000 and a particle size of 50 μm) are dissolved in 900 parts of N-methylacetamide to obtain a sulfonated polyether sulfone solution;

then, 5 parts of triphenylamine and 5 parts of polytetrafluoroethylene (with a molecular weight of 7000) are added into the prepared sulfonated polyether sulfone solution, and then the mixture is stirred at the temperature of 25 ℃ for 8 hours at the rotating speed of 50r/min, so as to obtain a mixed solution;

finally, pouring the prepared mixed solution into a stainless steel mold, placing the mixed solution and the mold in a baking oven, standing for 5h at the temperature of 90 ℃, and then standing for 8h at the temperature of 100 ℃ to obtain the composite ion exchange membrane S₉₀P₅T₅。

Testing the prepared composite ion exchange membrane S₉₀P₅T₅The results are shown in tables 1 to 3.

Example 2

Firstly, 90 parts of sulfonated polyether sulfone (with a sulfonation degree of 50%, a molecular weight of 60000 and a particle size of 50 μm) are dissolved in 900 parts of N-methylacetamide to obtain a sulfonated polyether sulfone solution;

then, adding 7 parts of triphenylamine and 3 parts of polytetrafluoroethylene (with a molecular weight of 7000) into the prepared sulfonated polyether sulfone solution, and stirring at a temperature of 25 ℃ and a rotating speed of 50r/min for 8 hours to obtain a mixed solution;

finally, pouring the prepared mixed solution into a stainless steel mold, placing the mixed solution and the mold in a baking oven, standing for 5h at the temperature of 90 ℃, and then standing for 8h at the temperature of 100 ℃ to obtain the composite ion exchange membrane S₉₀P₃T₇。

Testing the prepared composite ion exchange membrane S₉₀P₃T₇The results are shown in tables 1 to 3.

Example 3

Firstly, 90 parts of sulfonated polyether sulfone (with a sulfonation degree of 50%, a molecular weight of 60000 and a particle size of 50 μm) are dissolved in 900 parts of N-methylacetamide to obtain a sulfonated polyether sulfone solution;

then, 3 parts of triphenylamine and 7 parts of polytetrafluoroethylene (with a molecular weight of 7000) are added into the prepared sulfonated polyether sulfone solution, and then the mixture is stirred at the temperature of 25 ℃ for 8 hours at the rotating speed of 50r/min, so as to obtain a mixed solution;

finally, thePouring the prepared mixed solution into a stainless steel mold, placing the mixed solution and the mold in a baking oven, standing at 90 ℃ for 5h, and then standing at 100 ℃ for 8h to obtain the composite ion exchange membrane S₉₀P₇T₃。

Testing the prepared composite ion exchange membrane S₉₀P₇T₃The results are shown in tables 1 to 3.

Example 4

Composite ion exchange membrane 2MS prepared in the manner of example 1₉₀P₅T₅Except that dimethylacetamide was used as the solvent.

Testing the prepared composite ion exchange membrane 2MS₉₀P₅T₅The results are shown in tables 1 to 3.

Comparative example 1

A composite ion-exchange membrane S was prepared in the manner as in example 1₉₀T₁₀Except that "10 parts of triphenylamine" was used in comparative example 1 instead of "5 parts of triphenylamine and 5 parts of polytetrafluoroethylene" in example 1.

Testing the prepared composite ion exchange membrane S₉₀T₁₀The results are shown in tables 1 to 3.

Comparative example 2

A composite ion-exchange membrane S was prepared in the manner as in example 1₉₀P₁₀Except that "10 parts of polytetrafluoroethylene" was used in comparative example 1 instead of "5 parts of triphenylamine and 5 parts of polytetrafluoroethylene" in example 1.

Testing the prepared composite ion exchange membrane S₉₀P₁₀The results are shown in tables 1 to 3.

Comparative example 3

Firstly, 100 parts of sulfonated polyether sulfone (with the sulfonation degree of 50%, the molecular weight of 60000 and the particle size of 50 μm) are dissolved in 900 parts of N-methylacetamide to obtain a sulfonated polyether sulfone solution;

and then pouring the prepared sulfonated polyether sulfone solution into a stainless steel mold, placing the sulfonated polyether sulfone solution and the mold in a drying oven, standing for 5 hours at the temperature of 90 ℃, and then standing for 8 hours at the temperature of 100 ℃ to obtain the ion exchange membrane SPES.

The SPES performance of the ion exchange membranes thus obtained was tested and the results are shown in tables 1 to 3.

TABLE 1

According to the data in table 1, if and only if triphenylamine and polytetrafluoroethylene are used as dopants at the same time, the prepared composite ion exchange membrane can have higher ion exchange capacity, tensile strength and water absorption rate at the same time.

TABLE 2

As can be seen from the data in table 2, the prepared composite ion exchange membrane can simultaneously have high conductivity, vanadium ion permeability and ion selectivity when and only when triphenylamine and polytetrafluoroethylene are simultaneously used as dopants.

TABLE 3

As can be seen from the data in table 3, the prepared composite ion exchange membrane can have high coulombic efficiency, voltage efficiency and energy efficiency simultaneously, if and only if triphenylamine and polytetrafluoroethylene are used simultaneously as dopants.

It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.