Preparation method and application of self-microporous non-fluoride ion polymer and ion exchange membrane

Abstract

The application relates to a preparation method and application of a self-microporous non-fluoride ion polymer and an ion exchange membrane, relates to the field of high polymer structure design, and the self-microporous non-fluoride ion polymer is characterized in that the polymer and the membrane have a structure of formula (1): wherein x and y are molar percentages of sulfonated structure units and other functionalized structure units in total units, x=25% to 95%, y=75% to 5%; R is any one or two structures as follows: due to the existence of rigid and twisted monomers in the polymer, and the fact that the polymer main chain does not contain fluorine groups and ether bonds and other sites vulnerable to free radical attack, the self-microporous non-fluoride ion polymer has high ion selectivity, excellent ion transmission capacity and strong anti-free radical oxidation stability, and has wide application prospects in the field of electrochemical energy storage.

Description

Technical Field

[0001] This invention relates to the field of polymer structure design, specifically to a method for synthesizing a non-fluorinated ion polymer containing self-porous monomers and the preparation and application of ion exchange membranes. Background Technology

[0002] The pollution and carbon emissions from the extraction and combustion of fossil fuels have harmed the environment. Shifting the energy mix from fossil fuels to renewable energy technologies plays a crucial role in addressing complex environmental and economic challenges. Developing emerging energy conversion technologies based on fuel cells, water electrolysis for hydrogen production, flow batteries (RFB), and electrochemical hydrogen compression (EHC) is one of the most promising ways to reduce carbon emissions. Among these technologies, ion exchange membranes (IEMs), as key components in many energy conversion technologies, need to meet various performance requirements, such as high ionic conductivity, high selectivity, high stability, low permeability, and low cost.

[0003] Among them, perfluorosulfonic acid (PFSA) proton exchange membranes (such as Nafion) are among the most successful commercially available IEMs due to their excellent mechanical and oxidative stability, and the good proton conductivity under humid conditions formed by the separation of hydrophobic and hydrophilic phases. Despite their wide application, Nafion also has some drawbacks, including high permeability, poor water retention, and high cost. Furthermore, due to its perfluorinated framework structure, Nafion's preparation process also causes environmental pollution. Therefore, the development of a high-performance, environmentally friendly, and low-cost IEM is of great significance.

[0004] Current research focuses on ion exchange membranes that can replace PFSA membranes, with sulfonated aromatic polymers being one of the most promising materials. Sulfonated aromatic polymers are generally simple to synthesize, have inexpensive raw materials, and their synthesis process is environmentally friendly. Furthermore, aromatic polymers typically possess higher glass transition temperatures and greater oxidation stability, while their permeability is significantly lower than that of PFSA membranes. However, due to the relatively weak hydrophilic / hydrophobic phase separation ability of the polymer backbone, it is difficult to achieve the construction of continuous ion transport channels through self-assembly. Therefore, even at high ion exchange capacities (IEC), their conductivity is lower than that of PFSA membranes, and further increasing the IEC leads to severe swelling, resulting in a significant decrease in membrane mechanical stability.

[0005] In recent years, porous polymers (PIMs) have shown great advantages in ion exchange membrane applications due to their high specific surface area and porous structure, and have also provided new insights into polymer structure design. PIMs are composed of rigid and twisted macromolecules, resulting in low solid-state packing efficiency, thus generating high free volume and providing interconnected micropores smaller than 2 nm. The unique pore structure of PIMs provides channels for ion transport, improving the ionic conductivity of the membrane while suppressing membrane swelling. Functionalization of PIM-type polymers has led to the creation of membranes with promising applications in electrochemical devices. Previous reports have shown that adding ionizable functional groups, such as amide oximes, to alkaline electrolyte solutions can produce cation exchange membranes with moderate to high ionic conductivity, but exhibiting poor ionic conductivity at lower pH levels (even in a sodium chloride solution at pH 7 at 80°C, the conductivity is only 10). -4 S·cm -1 Therefore, there is a strong need to develop ion-conducting polymeric membranes (PIMs) with negatively charged functional groups at neutral pH, such as sulfonic acid groups. Recent development and research of microporous polymers have provided a new platform for designing ion exchange membranes with molecularly defined pore structures and size-restricted functions, enabling rapid and highly selective ion transport. Zuo et al. reported a polymer with a rigid and twisted framework to produce membranes with sub-nanometer-sized confined ion channels carrying negative charges. The convenient transport of protons and cations through these membranes and their high selectivity enable efficient and stable operation of alkaline redox flow batteries and proton exchange membrane fuel cells. Ye et al. reported the preparation of size-selective ion exchange membranes by sulfonation of spirofluorene-based microporous polymers and demonstrated their high ion selectivity in flow batteries.

[0006] However, the use of fluorinated monomers in the above structures contradicts the concept of green environmental protection. Post-sulfonation requires sulfonating agents to functionalize the polymer, and the uncertainty of the sulfonation position is detrimental to phase separation and membrane performance improvement. Furthermore, the polymer carries the risk of cross-linking. In addition, the chemical stability of such polymer membranes may be low. In these polymer structures, ether bonds are the most common heteroatom bonds on the main chain, usually generated by polymerization reactions where monomer molecules are linked together. The oxygen in the ether increases the electron density of adjacent aryl rings through electron-donating effects, thereby weakening resistance to oxidants. Therefore, the oxidative stability of such polymer membranes is low. Since ether groups do not play a key role in PEM performance, removing ether bonds from the polymer structure is an effective method to improve the chemical stability of PEMs. However, the synthesis process of ether-free polymer electrolytes is usually relatively complex and requires expensive metal catalysts. Summary of the Invention

[0007] The purpose of this invention is to provide a method for synthesizing a non-fluorinated ion-exchange polymer containing microporous monomers, and the preparation and application of an ion-exchange membrane. This type of polymer and ion-exchange membrane does not contain fluorine, making it environmentally friendly. Furthermore, due to the presence of the microporous structure and the absence of ether bonds in the polymer backbone, the ion selectivity, transport capacity, and antioxidant stability of the ion-exchange membrane can be improved, enabling its application in electrochemical energy storage devices.

[0008] This invention provides a method for preparing a microporous non-fluorinated ion polymer and an ion exchange membrane, and their applications. The polymer and membrane have the structure of formula (1):

[0009]

[0010] Where x and y are the molar percentages of sulfonated structural units and other functionalized structural units in the total number of units, x = 25% to 95% and y = 75% to 5%.

[0011] R can be any one or two of the structures shown in equation (2):

[0012]

[0013] The preparation of the self-porous non-fluorinated ionic polymer of the present invention includes the following specific steps:

[0014] (1) Monomer 1 (SBI) of formula (3) reacts with monomers 4-cyanobenzaldehyde and 4-formylbenzenesulfonic acid to form random copolymer of formula (4);

[0015] (2) The polymer of formula (4) reacts with the functionalizing agent to form the polymer of formula (1);

[0016] The structure of monomer 1 in formula (3) is as follows:

[0017]

[0018] The structure of the polymer in formula (4) is as follows:

[0019]

[0020] (3) In step (2), the R of polymer pair in formula (4) is -CN. If R is other functional groups, then formula (4) reacts with the corresponding different functionalized reagents to obtain the corresponding different R structures.

[0021] Preferably, the suitable molar ratio of the molar amount of monomer SBI in step (1) to the sum of the molar amounts of the other two monomers (4-formylbenzenesulfonic acid and 4-cyanobenzaldehyde) is 1:(1 to 1.2), wherein the ratio between 4-formylbenzenesulfonic acid and 4-cyanobenzaldehyde is consistent with the values ​​of x and y in formula (4), and the ratio range is (0.25 to 0.95):(0.75 to 0.05).

[0022] Preferably, the reaction solvent used in step (1) is dichloromethane, the acid catalyst is methanesulfonic acid, and the suitable molar ratio of methanesulfonic acid to monomer 1 is (8-10):1.

[0023] Preferably, the reaction temperature in step (1) is room temperature and the reaction time is 2 to 4 hours;

[0024] The preparation method of the self-microporous non-fluorine ion exchange membrane includes the following steps: dissolving the self-microporous sulfonated polymer prepared above in a solvent to prepare a casting solution, then casting the casting solution onto a substrate, and obtaining the ion exchange membrane after the solvent is completely dried.

[0025] The selected solvents include dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0026] This invention also provides the application of the above-mentioned microporous non-fluorine ion exchange membrane in electrochemical devices, wherein the electrochemical devices are hydrogen-oxygen fuel cells, iron-chromium redox flow batteries, vanadium redox flow batteries, and aqueous organic redox flow batteries, etc.

[0027] This invention proposes a method for preparing a self-contained microporous non-fluorinated ion exchange membrane. Using methanesulfonic acid as a catalyst, a Friedel-Crafts reaction is conducted to generate a non-fluorinated self-contained microporous ion polymer. The preparation method is simple, the preparation conditions are mild, and no precious metal catalyst is required. Furthermore, the prepared ion polymer does not contain ether bonds or other groups easily attacked by free radicals, exhibiting strong resistance to free radical oxidation. The sub-nanometer microporous structure provides channels for ion transport, and the rigidity of the main chain ensures high mechanical properties and resistance to swelling of the membrane. Attached Figure Description

[0028] Figure 1 The infrared spectrum of the polymer obtained in Example 1 of the present invention;

[0029] Figure 2 The above is the 1H NMR spectrum of the polymer obtained in Example 1 of this invention.

[0030] Figure 3 The infrared spectrum of the polymer obtained in Example 11 of the present invention;

[0031] Figure 4The hydrogen nuclear magnetic resonance spectrum of the polymer obtained in Example 11 of this invention;

[0032] Figure 5 The energy efficiency performance of the self-microporous non-fluorine ion exchange membranes prepared in Examples 1-3 of the present invention, assembled into iron-chromium redox flow batteries;

[0033] Figure 6 The coulombic efficiency performance of the battery assembled into an iron-chromium flow battery using the microporous non-fluorine ion exchange membranes prepared in Examples 1-3 of the present invention.

[0034] Figure 7 The battery voltage efficiency performance of the self-porous non-fluorine ion exchange membranes prepared in Examples 1-3 of the present invention, assembled into iron-chromium redox flow batteries;

[0035] Figure 8 The battery energy efficiency performance of the self-porous non-fluorine ion exchange membranes prepared in Examples 1-3 of the present invention assembled into an aqueous organic flow battery.

[0036] Figure 9 The coulombic efficiency performance of the battery assembled into an aqueous organic flow battery using the microporous non-fluorinated ion exchange membranes prepared in Examples 1-3 of the present invention.

[0037] Figure 10 The battery voltage efficiency performance of the self-porous non-fluorinated ion exchange membranes prepared in Examples 1-3 of the present invention, assembled into an aqueous organic flow battery. Detailed Implementation

[0038] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0039] I. Examples of the polymer of formula (4) of the present invention are as follows:

[0040] Example 1

[0041] Take a 50 mL three-necked flask and weigh out monomers SBI (4 mmol, 1.35 g), 4-acrylbenzaldehyde (2 mmol, 0.26 g), and 4-formylbenzenesulfonic acid (3.4 mmol, 0.60 g). Add 5 mL of dichloromethane solvent and stir mechanically until all monomers are dissolved. Then, add methanesulfonic acid (32 mmol, 2.07 mL) dropwise under an ice-water bath. After the addition is complete, remove the ice-water bath and continue the reaction. During the reaction, the solution gradually becomes viscous. After 3 hours, pour the reaction solution into ammonia water to obtain a white fibrous solid. Wash the solid with water several times until neutral, filter, and dry in a vacuum oven at 100 °C for 24 hours to obtain polymer (4). The obtained polymer is used to prepare an ion exchange membrane with a thickness of 40–50 μm by solvent evaporation.

[0042] Example 2

[0043] Take a 50 mL three-necked flask and weigh out monomers SBI (4 mmol, 1.35 g), 4-acrylbenzaldehyde (1.6 mmol, 0.21 g), and 4-formylbenzenesulfonic acid (3.6 mmol, 0.67 g). Add 5 mL of dichloromethane solvent and stir mechanically until all monomers are dissolved. Then, add methanesulfonic acid (32 mmol, 2.07 mL) dropwise under an ice-water bath. After the addition is complete, remove the ice-water bath and continue the reaction. During the reaction, the solution gradually becomes viscous. After 2.5 h, pour the reaction solution into ammonia water to obtain a white fibrous solid. Wash the solid with water several times until neutral, filter, and dry in a vacuum oven at 100 °C for 24 h to obtain polymer (4). The obtained polymer is used to prepare an ion exchange membrane with a thickness of 40–50 μm by solvent evaporation.

[0044] Example 3

[0045] Take a 50 mL three-necked flask and weigh out monomers SBI (4 mmol, 1.35 g), 4-acrylbenzaldehyde (1.4 mmol, 0.18 g), and 4-formylbenzenesulfonic acid (3.8 mmol, 0.71 g). Add 5 mL of dichloromethane solvent and stir mechanically until all monomers are dissolved. Then, add methanesulfonic acid (32 mmol, 2.07 mL) dropwise under an ice-water bath. After the addition is complete, remove the ice-water bath and continue the reaction. During the reaction, the solution gradually becomes viscous. After 2 hours, pour the reaction solution into ammonia water to obtain a white fibrous solid. Wash the solid with water several times until neutral, filter, and dry in a vacuum oven at 100 °C for 24 hours to obtain polymer (4). The obtained polymer is used to prepare an ion exchange membrane with a thickness of 40–50 μm by solvent evaporation.

[0046] Example 4

[0047] Take a 50 mL three-necked flask and weigh out monomers SBI (4 mmol, 1.35 g), 4-acrylbenzaldehyde (1.8 mmol, 0.24 g), and 4-formylbenzenesulfonic acid (3.2 mmol, 0.63 g). Add 5 mL of dichloromethane solvent and stir mechanically until all monomers are dissolved. Then, add methanesulfonic acid (32 mmol, 2.07 mL) dropwise under an ice-water bath. After the addition is complete, remove the ice-water bath and continue the reaction. During the reaction, the solution gradually becomes viscous. After 3 hours, pour the reaction solution into ammonia water to obtain a white fibrous solid. Wash the solid with water several times until neutral, filter, and dry in a vacuum oven at 100 °C for 24 hours to obtain polymer (4). The obtained polymer is used to prepare an ion exchange membrane with a thickness of 40–50 μm by solvent evaporation.

[0048] Example 5

[0049] Take a 50 mL three-necked flask and weigh out monomers SBI (4 mmol, 1.35 g), 4-acrylbenzaldehyde (3.2 mmol, 0.42 g), and 4-formylbenzenesulfonic acid (2 mmol, 0.37 g). Add 5 mL of dichloromethane solvent and stir mechanically until all monomers are dissolved. Then, add methanesulfonic acid (32 mmol, 2.07 mL) dropwise under an ice-water bath. After the addition is complete, remove the ice-water bath and continue the reaction. During the reaction, the solution gradually becomes viscous. After 3 hours, pour the reaction solution into ammonia water to obtain a white fibrous solid. Wash the solid with water several times until neutral, filter, and dry in a vacuum oven at 100 °C for 24 hours to obtain polymer (4). The obtained polymer is used to prepare an ion exchange membrane with a thickness of 40–50 μm by solvent evaporation.

[0050] Example 6

[0051] Take a 50 mL three-necked flask and weigh out monomers SBI (4 mmol, 1.35 g), 4-acrylbenzaldehyde (3 mmol, 0.39 g), and 4-formylbenzenesulfonic acid (2.2 mmol, 0.41 g). Add 5 mL of dichloromethane solvent and stir mechanically until all monomers are dissolved. Then, add methanesulfonic acid (32 mmol, 2.07 mL) dropwise under an ice-water bath. After the addition is complete, remove the ice-water bath and continue the reaction. During the reaction, the solution gradually becomes viscous. After 3 hours, pour the reaction solution into ammonia water to obtain a white fibrous solid. Wash the solid with water several times until neutral, filter, and dry in a vacuum oven at 100 °C for 24 hours to obtain the polymer of formula (4). The ion exchange membrane obtained by solvent evaporation of the obtained polymer has a thickness of 40–50 μm.

[0052] Example 7

[0053] Take a 50 mL three-necked flask and weigh out monomers SBI (4 mmol, 1.35 g), 4-acrylbenzaldehyde (2.8 mmol, 0.37 g), and 4-formylbenzenesulfonic acid (2.4 mmol, 0.45 g). Add 5 mL of dichloromethane solvent and stir mechanically until all monomers are dissolved. Then, add methanesulfonic acid (32 mmol, 2.07 mL) dropwise under an ice-water bath. After the addition is complete, remove the ice-water bath and continue the reaction. During the reaction, the solution gradually becomes viscous. After 3 hours, pour the reaction solution into ammonia water to obtain a white fibrous solid. Wash the solid several times with water until neutral, filter, and dry in a vacuum oven at 100 °C for 24 hours to obtain polymer (4). The obtained polymer is used to prepare an ion exchange membrane with a thickness of 40–50 μm by solvent evaporation.

[0054] Example 8

[0055] Take a 50 mL three-necked flask and weigh out monomers SBI (4 mmol, 1.35 g), 4-acrylbenzaldehyde (2.6 mmol, 0.34 g), and 4-formylbenzenesulfonic acid (2.6 mmol, 0.48 g). Add 5 mL of dichloromethane solvent and stir mechanically until all monomers are dissolved. Then, add methanesulfonic acid (32 mmol, 2.07 mL) dropwise under an ice-water bath. After the addition is complete, remove the ice-water bath and continue the reaction. During the reaction, the solution gradually becomes viscous. After 3 hours, pour the reaction solution into ammonia water to obtain a white fibrous solid. Wash the solid several times with water until neutral, filter, and dry in a vacuum oven at 100 °C for 24 hours to obtain polymer (4). The obtained polymer is used to prepare an ion exchange membrane with a thickness of 40–50 μm by solvent evaporation.

[0056] Example 9

[0057] Take a 50 mL three-necked flask and weigh out monomers SBI (4 mmol, 1.35 g), 4-acrylbenzaldehyde (2.4 mmol, 0.31 g), and 4-formylbenzenesulfonic acid (2.8 mmol, 0.52 g). Add 5 mL of dichloromethane solvent and stir mechanically until all monomers are dissolved. Then, add methanesulfonic acid (32 mmol, 2.07 mL) dropwise under an ice-water bath. After the addition is complete, remove the ice-water bath and continue the reaction. During the reaction, the solution gradually becomes viscous. After 3 hours, pour the reaction solution into ammonia water to obtain a white fibrous solid. Wash the solid several times with water until neutral, filter, and dry in a vacuum oven at 100 °C for 24 hours to obtain polymer (4). The obtained polymer is used to prepare an ion exchange membrane with a thickness of 40–50 μm by solvent evaporation.

[0058] Example 10

[0059] Take a 50 mL three-necked flask and weigh out monomers SBI (4 mmol, 1.35 g), 4-acrylbenzaldehyde (2.2 mmol, 0.29 g), and 4-formylbenzenesulfonic acid (3 mmol, 0.56 g). Add 5 mL of dichloromethane solvent and stir mechanically until all monomers are dissolved. Then, add methanesulfonic acid (32 mmol, 2.07 mL) dropwise under an ice-water bath. After the addition is complete, remove the ice-water bath and continue the reaction. During the reaction, the solution gradually becomes viscous. After 3 hours, pour the reaction solution into ammonia water to obtain a white fibrous solid. Wash the solid with water several times until neutral, filter, and dry in a vacuum oven at 100 °C for 24 hours to obtain polymer (4). The obtained polymer is used to prepare an ion exchange membrane with a thickness of 40–50 μm by solvent evaporation.

[0060] II. Examples of other methods for preparing non-fluorinated ionic polymers with self-contained micropores according to the present invention are as follows:

[0061] Example 11

[0062] Take a 250 mL three-necked flask, weigh the polymer obtained in Example 1 (1.18 mmol, 0.6 g), add 40 mL of dimethyl sulfoxide solvent, heat to 65 °C and purge with nitrogen. Under magnetic stirring, the polymer is completely dissolved. After purging with nitrogen for 0.5 h, the hydroxylamine solution is slowly added dropwise to the three-necked flask using a constant pressure dropping funnel. After 20 min of addition, the temperature is raised to 69 °C, and the reaction is continued at this temperature for 20 h. After the reaction is completed and cooled to room temperature, the reaction solution is poured into ethyl acetate to obtain a white polymer. After washing with water several times, it is dried in a 100 °C oven for 24 h. The obtained polymer is the self-porous non-fluorinated ion polymer functionalized with nitrile amamidoxime, where R in formula (2) is the amamidoxime group. The thickness of the ion exchange membrane obtained by solvent evaporation of the obtained polymer is 40-50 μm.

[0063] Example 12

[0064] Take a 250 mL three-necked flask, weigh the polymer obtained in Example 2 (1.11 mmol, 0.56 g), add 40 mL of dimethyl sulfoxide solvent, heat to 65 °C and purge with nitrogen. Under magnetic stirring, the polymer is completely dissolved. After purging with nitrogen for 0.5 h, the hydroxylamine solution is slowly added dropwise to the three-necked flask using a constant pressure dropping funnel. After 20 min of addition, the temperature is raised to 69 °C, and the reaction is continued at this temperature for 20 h. After the reaction is completed and cooled to room temperature, the reaction solution is poured into ethyl acetate to obtain a white polymer. After washing with water several times, it is dried in a 100 °C oven for 24 h. The obtained polymer is the self-porous non-fluorinated ion polymer functionalized with nitrile amamidoxime, where R in formula (2) is the amamidoxime group. The thickness of the ion exchange membrane obtained by solvent evaporation of the obtained polymer is 40-50 μm.

[0065] Example 13

[0066] Take a 100 mL three-necked flask and weigh the polymer obtained in Example 1 (5.38 mmol, 4.56 g). Mix it with 15 mL concentrated H2SO4, 15 mL H2O and 10 mL glacial acetic acid under nitrogen atmosphere, heat to 105 °C for 48 h, cool and pour into 200 mL deionized water. Filter and collect the precipitate, then wash it several times with water and methanol. Dry the obtained polymer in a vacuum oven at 50 °C for 24 h. The obtained polymer is a microporous non-fluorinated ion exchange polymer after carboxyl functionalization of nitrile groups, where R in formula (2) is a carboxyl group. The ion exchange membrane obtained by solvent evaporation of the obtained polymer has a thickness of 40–50 μm.

[0067] Example 14

[0068] Take a 100 mL three-necked flask and weigh the polymer obtained in Example 2 (5.06 mmol, 4.29 g). Mix it with 15 mL concentrated H2SO4, 15 mL H2O and 10 mL glacial acetic acid under nitrogen atmosphere, heat to 105 °C for 48 h, cool and pour into 200 mL deionized water. Filter and collect the precipitate, then wash it several times with water and methanol. Dry the obtained polymer in a vacuum oven at 50 °C for 24 h. The obtained polymer is a microporous non-fluorinated ion exchange polymer after carboxyl functionalization of nitrile groups, where R in formula (2) is a carboxyl group. The ion exchange membrane obtained by solvent evaporation of the obtained polymer has a thickness of 40–50 μm.

[0069] Example 15

[0070] Take a 250 mL three-necked flask, weigh the polymer obtained in Example 1 (2.75 mmol, 2.33 g), add 60 mL of dimethyl sulfoxide to the flask, stir at 20 °C for 1 h, then add potassium carbonate (1.5 g, 10.8 mmol) to the above solution until the pH of the resulting mixture is between 9 and 10. Then add 25 wt% H2O2 (10 mL, 65.3 mmol) dropwise. Stir the reaction mixture at 20 °C for 24 h. After the reaction is complete, pour the mixture into 500 mL of water and stir at 20 °C overnight. Filter the obtained solid, wash it several times with water and methanol, and then dry it in a vacuum oven at 25 °C for 24 h. The obtained polymer is a self-contained microporous non-fluorinated ion polymer after nitrile groups are functionalized with amino groups, corresponding to R in formula (2) as an amino group. The thickness of the ion exchange membrane obtained by solvent evaporation of the obtained polymer is 40-50 μm.

[0071] Example 16

[0072] Take a 250 mL three-necked flask, weigh the polymer obtained in Example 2 (2.44 mmol, 2.07 g), add 60 mL of dimethyl sulfoxide to the flask, stir at 20 °C for 1 h, then add potassium carbonate (1.5 g, 10.8 mmol) to the above solution until the pH of the resulting mixture is between 9 and 10. Then add 25 wt% H2O2 (10 mL, 65.3 mmol) dropwise. Stir the reaction mixture at 20 °C for 24 h. After the reaction is complete, pour the mixture into 500 mL of water and stir at 20 °C overnight. Filter the obtained solid, wash it several times with water and methanol, and then dry it in a vacuum oven at 25 °C for 24 h. The obtained polymer is a self-porous non-fluorinated ion polymer after nitrile groups are functionalized with amino groups, corresponding to R in formula (2) as an amino group. The thickness of the ion exchange membrane obtained by solvent evaporation of the obtained polymer is 40-50 μm.

[0073] Example 17

[0074] Take a 250 mL three-necked flask and weigh the polymer obtained in Example 1 (3.13 mmol, 2.65 g), sodium azide (20 mmol, 1.3 g), anhydrous zinc chloride (20 mmol, 2.7 g), and 50 mL of dimethylacetamide. Add the mixture to the flask and stir at 120 °C for 2.5 days. After cooling, pour the mixture into 50 mL of 1 M HCl and heat the mixture at 60 °C for 1 hour. After filtration, wash the product sequentially with diluted HCl (36 wt% HCl: H2O = 1:50 (v:v)), H2O, and acetone. Dry the obtained polymer in a vacuum oven at 120 °C for 24 hours. The obtained polymer is a self-porous non-fluorinated ion polymer with nitrile groups functionalized with tetrazolium, where R in formula (2) is a tetrazolium group. The ion exchange membrane obtained by solvent evaporation of the obtained polymer has a thickness of 40–50 μm.

[0075] Example 18

[0076] Take a 250 mL three-necked flask and weigh the polymer obtained in Example 2 (2.78 mmol, 2.27 g), sodium azide (20 mmol, 1.3 g), anhydrous zinc chloride (20 mmol, 2.7 g), and 50 mL of dimethylacetamide. Add the mixture to the flask and stir at 120 °C for 2.5 days. After cooling, pour the mixture into 50 mL of 1 M HCl and heat the mixture at 60 °C for 1 hour. After filtration, wash the product sequentially with diluted HCl (36 wt% HCl: H2O = 1:50 (v:v)), H2O, and acetone. Dry the obtained polymer in a vacuum oven at 120 °C for 24 hours. The obtained polymer is a self-porous non-fluorinated ion polymer with nitrile groups functionalized with tetrazolium, where R in formula (2) is a tetrazolium group. The ion exchange membrane obtained by solvent evaporation of the obtained polymer has a thickness of 40–50 μm.

[0077] Experimental Test

[0078] 1. Polymer structure analysis

[0079] The infrared spectrum of the product obtained in Example 1 is as follows: Figure 1 As shown, the 1H NMR spectrum is as follows Figure 2 As shown, the infrared spectrum of the product obtained in Example 11 is as follows. Figure 1 As shown, the 1H NMR spectrum is as follows Figure 2 As shown. For each Figure 1 , Figure 2 Figure 3 , Figure 4 Analysis was conducted, demonstrating the successful preparation of the polymer.

[0080] 2. Solubility test

[0081] The polymers obtained in Examples 1-3 were dissolved in 5 wt% solutions prepared with different high-boiling-point organic solvents, and their degree of dissolution was observed. The results are shown in Table 1. All polymers showed good solubility and no gelation occurred.

[0082] Table 1

[0083]

[0084] 3. Performance testing of ion exchange membranes

[0085] The properties of the ion exchange membranes prepared from the polymers obtained in Examples 1-3 were tested. Water absorption and swelling were tested at 80°C, electrical conductivity was tested at 80°C using an electrochemical workstation, and mechanical properties were tested using a universal tensile testing machine. The results are shown in Table 2.

[0086] Table 2

[0087] membrane <![CDATA[K + Electrical conductivity (mS / cm) Water absorption rate (%) Swelling rate (%) Tensile strength (MPa) Example 1 27.11 21.81 1.85 74.42 Example 2 64.47 30.10 9.80 57.66 Example 3 60.27 45.00 10.20 37.78

[0088] 4. Antioxidant stability test

[0089] The ion exchange membrane prepared by the polymer in Example 2 was immersed in Fenton's reagent (3% H2O2, 2ppm FeSO4) at 80°C for 3 hours, and the membrane remained intact. This indicates that the ion exchange membrane provided by the present invention has high resistance to free radical oxidation.

[0090] 5. Flow battery performance testing

[0091] Figure 5-7 The membranes prepared in Examples 1-3 were used to test the battery performance of an iron-chromium redox flow battery system. ICRFB single cells were tested using a battery testing system; the effective area of ​​the membrane was 2 × 2 cm⁻¹. 2 Both electrodes on both sides of the membrane contained 20 mL of 1M FeCl2 / 1MCrCl3 / 3M HCl electrolyte, which was circulated by a pump at a flow rate maintained at approximately 55 mL / min. Battery performance was tested at 65°C with current densities ranging from 60 to 200 mA / cm². 2 The voltage was set to 0.7 to 1.2V. The results are as follows: Figure 5-7 As shown, the battery in Example 2 exhibits the best overall performance, with the highest energy efficiency and voltage efficiency, and a coulombic efficiency higher than that of Example 1 and comparable to that of Example 3, particularly at 60 mA / cm². 2 At the given current density, Example 1 exhibits an energy efficiency of 87.7%, a coulombic efficiency of 95.1%, and a voltage efficiency of 92.2%.

[0092] Figure 8-10The membranes prepared in Examples 1-3 were tested for battery performance in a potassium ferrocyanide / anthraquinone-2,7-disulfonate saline organic flow battery system. ICRFB single cells were tested using a battery testing system; the effective area of ​​the membrane was 2 × 2 cm⁻¹. 2 The positive electrode contains 20 mL of 0.1 M KOH / 0.3 M K4[Fe(CN)6] electrolyte, circulated by a circulation pump. The negative electrode contains 20 mL of 0.1 M KOH / 0.1 M anthraquinone-2,7-disulfonate sodium salt electrolyte, circulated by a circulation pump. The electrolyte flow rate is maintained at approximately 60 mL / min. Battery performance is tested at 25 °C, with current densities ranging from 20 to 140 mA / cm². 2 The voltage was set to 0.2 to 1.0V. The results are as follows: Figure 8-10 As shown, the battery in Example 2 exhibits the best overall performance, particularly at 20 mA / cm². 2 At the given current density, Example 1 has an energy efficiency of 90.9%, a coulombic efficiency of 99.3%, and a voltage efficiency of 91.6%.

[0093] The ion exchange membrane prepared in the experimental example was tested in the above experiments, which showed that the ion exchange membrane provided by the present invention has excellent comprehensive properties such as high conductivity, high swelling resistance and mechanical properties, and high resistance to free radical oxidation. It has excellent performance in iron-chromium redox flow batteries and aqueous organic redox flow batteries and has broad application prospects.

Claims

1. A non-fluorinated ionic polymer with its own micropores, characterized in that, The polymer has the structure of formula (1): Equation (1); Where x and y are the molar percentages of sulfonated structural units and other functionalized structural units in the total number of units, x = 25%~95% and y = 75%~5%; R stands for -CN.

2. The method for preparing the self-porous non-fluorinated ionic polymer according to claim 1, characterized in that, The specific steps include the following: (1) Monomer 1 (SBI) of formula (3) reacts with monomers 4-cyanobenzaldehyde and 4-formylbenzenesulfonic acid to form random copolymer of formula (4); (2) The polymer of formula (4) reacts with the functionalizing agent to form the polymer of formula (1); The structure of monomer 1 in formula (3) is as follows: Equation (3); The structure of the polymer in formula (4) is as follows: Equation (4); (3) In step (2), the R of the polymer pair in formula (4) is -CN, i.e., formula (1).

3. The method according to claim 2, characterized in that, In step (1), the suitable molar ratio of the molar amount of monomer SBI to the sum of the molar amounts of the other two monomers (4-formylbenzenesulfonic acid and 4-cyanobenzaldehyde) is 1:(1~1.2), wherein the ratio between 4-formylbenzenesulfonic acid and 4-cyanobenzaldehyde is consistent with the values ​​of x and y in formula (4), and the ratio range is (0.25~0.95):(0.75~0.05).

4. The method according to claim 2, characterized in that, The reaction solvent used in step (1) is dichloromethane, the acid catalyst is methanesulfonic acid, and the suitable molar ratio of methanesulfonic acid to monomer 1 is (8~10):

1.

5. The method according to claim 2, characterized in that, In step (1), the reaction temperature is room temperature and the reaction time is 2-4 h.

6. The application of the microporous non-fluorinated ion exchange membrane prepared by the microporous non-fluorinated ion polymer according to claim 1.

7. The method for preparing a self-microporous non-fluorinated ion exchange membrane using the self-microporous non-fluorinated ion polymer according to claim 1, characterized in that, The process includes the following steps: dissolving the prepared microporous sulfonated polymer in a solvent to prepare a casting solution, then casting the casting solution onto a substrate, and obtaining an ion exchange membrane after the solvent has completely dried.

8. The method according to claim 7, characterized in that, The solvent is selected from dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

9. The application of the self-porous non-fluorine ion exchange membrane prepared by the method of claim 7 in hydrogen-oxygen fuel cells and flow batteries.

10. The application according to claim 9, characterized in that, The flow battery is selected from iron-chromium flow batteries, vanadium flow batteries, and aqueous organic flow batteries.

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