High free volume type anion exchange membrane, preparation method and application

Abstract

The invention relates to a high free volume type anion exchange membrane, a preparation method and an application, the high free volume type anion exchange membrane comprises an ionomer with a repeating unit shown as a formula 1: in the formula 1, x and y are respectively molar percentages relative to the repeating unit; x + y = 100%; m is 0, 1 or 2; a <-> is selected from any one of I <->, Br <->, Cl <->, SCN <-> and OH <->; ar1 is selected from a condensed benzene compound; ar2 is selected from biaryl compounds. The ionic conductivity of the anion exchange membrane is greatly improved, the swelling behavior of the anion exchange membrane is inhibited, and the mechanical property and long-term stability of the anion exchange membrane are improved.

Description

Technical Field

[0001] This invention belongs to the field of anion exchange membrane materials, specifically relating to high free volume anion exchange membranes, their preparation methods, and applications. Background Technology

[0002] The consumption of traditional fossil fuels, coupled with excessive carbon emissions, has triggered a series of extreme weather events globally. Therefore, developing green and clean energy has become an urgent priority. Hydrogen combustion produces only water, thus gradually occupying a central position in the energy structure transformation. Water electrolysis, as an energy conversion device, is receiving widespread attention as an emerging renewable hydrogen production technology, especially anion exchange membrane electrolysis (AEMWEs). AEMWEs utilize low-cost, non-precious metal catalysts (such as Fe, Co, and Ni), combining the advantages of proton exchange membrane electrolysis (PEMWEs) and alkaline electrolysis (AWEs). This achieves high energy conversion efficiency while using low-cost, non-precious metal catalysts. Anion exchange membranes (AEMs), as core components of alkaline energy devices, have made some progress in various aspects. However, unfortunately, the current density of most current AEMWEs is still lower than that of advanced PEMWEs. In recent years, researchers have devoted a lot of effort to improving the performance of AEMWEs, among which improving the ion exchange capacity (IEC) of the anion exchange membrane to enhance electrolysis efficiency is one of the key approaches. However, this improvement scheme of IEC leads to higher water absorption (WU) and swelling ratio (SR). For example, the PBP-6-Pip membrane synthesized by Liu et al. has a higher water absorption rate (WU) and swelling ratio (SR) at 80°C. o At high temperatures, C has a value of 3.97. The IEC, and their WU and SR reached 189.6% and 69.5% respectively; compared to PBP-8-Pip membrane 3.76 The IEC (internal swelling capacity) of the membrane was improved to 162.9% and 60.9% for WU and SR, while the tensile strength decreased from 53.23 MPa to 42.32 MPa. Furthermore, excessive swelling may hinder carrier transport mechanisms, all due to the negative impact of high IEC. In addition, the introduction of ether-containing groups to construct ion conduction channels in anion exchange membranes (AEMs) can promote the aggregation of water molecules within the membrane through the polarity of the strong dipole units, thereby forming hydrated ion channels and enhancing microphase separation; however, aryl ether bonds are susceptible to OH groups. − The attack of these particles can exacerbate the degradation of AEMs, which can negatively impact the long-term stability of the device.

[0003] Therefore, how to achieve a balance between high ionic conductivity and structural stability and IEC, that is, to achieve high energy conversion efficiency at a lower IEC, is an important problem that AEMs urgently need to solve. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects in the prior art and to provide a high free volume anion exchange membrane, its preparation method and application. It not only greatly improves the ion conductivity of the anion exchange membrane and inhibits its swelling behavior, but also improves its mechanical properties and long-term stability.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A high free volume anion exchange membrane comprising an ionomer having repeating units as shown in Formula 1:

[0006] Formula 1 ; Where x and y are the molar percentages relative to the repeating unit, respectively; x + y = 100%; m is 0, 1, or 2; A is selected from I, Br, Cl, SCN. Any one of OH; Ar1 is selected from condensed benzene compounds; Ar2 is selected from biaryl compounds.

[0007] As a further technical solution, Ar1 is selected from... , , , , Any one of them.

[0008] As a further technical solution, the Ar2 is selected from... , , , , , Any one of them.

[0009] As a further technical solution, x=80-90%; y=10-20%.

[0010] A method for preparing a high free volume anion exchange membrane includes the following steps: Step 1: Add methylpiperidine and 1,4-dibromobutane to the first solvent and react at 60-70℃ for 20-28 h to obtain bromobutylpiperidine ionic liquid; Step 2: Add the biaryl compound, the condensed benzene compound and indigo to the second solvent, and then add trifluoroacetic acid and trifluoromethanesulfonic acid dropwise at 0°C. After reacting for 5-7 hours, the reaction is stopped to obtain the copolymer. Step 3: Add the copolymer obtained in Step 2 and the bromobutylpiperidine ionic liquid obtained in Step 1 to the second solvent, react at 82-88℃ for 40-56 h, stop the reaction, drop the reaction solution into the third solvent to precipitate the polymer, wash the polymer several times, and dry it to obtain the ionic polymer. Step 4: Add the ion polymer to the second solvent to prepare a polymer solution, then cast it into a membrane and dry it to obtain a high free volume anion exchange membrane.

[0011] As a further technical solution, in step 2, after the reaction is completed, post-processing is required. The post-processing includes pouring the reaction solution for producing the copolymer into deionized water, precipitating solids, cutting the solids into small pieces, removing acid with an alkaline aqueous solution and an alkaline isopropanol, washing until neutral, and then drying to obtain the copolymer.

[0012] As a further technical solution, in step 1, the molar ratio of 1,4-dibromobutane and methylpiperidine is 6-10:1; In step 2, the total amount of biaryl compounds and condensed benzene compounds, and the molar ratio of indigo, trifluoroacetic acid, and trifluoromethanesulfonic acid are 1:1.1-1.3:0.5-1.5:5-15; Among them, biaryl compounds account for 80-90% of the total molar amount of biaryl compounds and condensed benzene compounds, and condensed benzene compounds account for 10-20% of the total molar amount of biaryl compounds and condensed benzene compounds.

[0013] As a further technical solution, in step 4, the casting time is ≤3 h and the casting temperature is 50-90℃.

[0014] As a further technical solution, the first solvent is acetonitrile; As a further technical solution, the second solvent is dimethyl sulfoxide; As a further technical solution, the third solvent is ethyl acetate; As a further technical solution, the alkali in both the alkaline aqueous solution and the alkaline isopropanol is KOH.

[0015] An alkaline high free volume anion exchange membrane is obtained by immersing the high free volume anion exchange membrane in an alkaline solution.

[0016] The application of the high free volume anion exchange membrane or the alkaline high free volume anion exchange membrane in water electrolysis.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention introduces the sterically hindered monomer 9,10-bis(1-naphthyl)anthracene into a polymer backbone to prepare anion exchange membranes (AEMs). These large and rigid structural units of AEMs achieve high ionic conductivity while maintaining mechanical stability even at relatively low IEC (internal electrochemical conductivity). This is achieved by reducing chain packing density, thereby increasing the free volume within the membrane and reducing the resistance to hydroxide ion transport. 9,10-bis(1-naphthyl)anthracene possesses a rigid hydrophobic framework with large steric hindrance and can also act as a barrier against OH-. − This invention provides a protective barrier against corrosive attacks, thereby slowing down the degradation process. Furthermore, the invention introduces an indigo group; the sterically hindered monomer 9,10-bis(1-naphthyl)anthracene, along with indigo, strengthens the binding force and resistance to deformation between polymer chains through the superposition of multiple non-covalent intermolecular interactions and the synergistic restriction of rigidity and steric hindrance, thereby improving the mechanical strength of the anion exchange membrane.

[0018] 2. This invention synthesizes a polymer backbone with 9,10-bis(1-naphthyl)anthracene doping through a Friedel-Crafts alkylation polycondensation process, which results in polymer anion exchange membranes with good mechanical properties and dimensional stability.

[0019] 3. This invention uses a simple anion exchange method to prepare basic anion exchange membranes. The preparation process is simple and avoids the use of expensive metal catalysts in aromatic ether polymers. The preparation process is relatively simple and safe.

[0020] 4. The polymer anion exchange membrane designed in this invention can be modified with different anions according to actual needs to obtain anion exchange membranes with different anions. When immersed in alkaline solution, an alkaline anion exchange membrane is obtained, which has excellent alkali resistance and can be used for alkaline anion exchange membrane electrolysis of water.

[0021] In summary, the high free volume anion exchange membrane prepared by this invention not only greatly improves the ion conductivity of the anion exchange membrane and inhibits its swelling behavior, but also improves its mechanical properties and long-term stability. Moreover, the preparation process is simple, safe, and low in cost. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the high-efficiency water transport channel of the high free volume anion exchange membrane of the present invention; Figure 2 The above is the 1H NMR spectrum of the high free volume polymer of this invention; exist Figure 2 In the image, A: PTID-10, basement membrane NMR; B: PTID-10, ionization NMR; C: PTID-15, basement membrane NMR; D: PTID-15, ionization NMR; E: PTID-20, basement membrane NMR; F: PTID-20, ionization NMR. Figure 3 The graph shows the water absorption rate and swelling rate of the high free volume anion exchange membrane of the present invention. exist Figure 3 In the diagram, A: Water absorption rate; B: Swelling rate. Figure 4 Characterization of the water transport capacity of the high free volume anion exchange membrane of the present invention; Figure 5 Characterization of molecular chain segment distances for the high free volume anion exchange membrane of the present invention; Figure 6 MD molecular simulation of the high free volume anion exchange membrane of the present invention; exist Figure 6 In the diagram, A: PTID-0, water molecule distribution map; B: PTID-20, water molecule distribution map; C: PTID-0, free volume map; D: PTID-20, free volume map; Figure 7 Conductivity characterization of the high free volume anion exchange membrane of the present invention; Figure 8 Mechanical properties characterization of the high free volume anion exchange membrane of the present invention; Figure 9 Characterization of the gas permeation performance of the high free volume anion exchange membrane of the present invention; Figure 10 Cyclic voltammetric polarization curves of the high free volume anion exchange membrane of the present invention in water electrolysis devices under different concentrations of electrolyte; exist Figure 10 In the diagram, A: 60℃; B: 80℃; Figure 11 The in-situ durability curves of the high free volume anion exchange membrane of the present invention in water electrolysis devices under different concentrations of electrolyte are shown. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] All raw materials used in this invention are commercially available.

[0025] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0026] This invention uses the ionomer shown in Formula 2 as an example to introduce a method for preparing anion exchange membranes:

[0027] Formula 2 ; Where x + y = 100%.

[0028] Example 1 A high free volume anion exchange membrane (PTID-10) is prepared by the following steps: Step 1: At room temperature, methylpiperidine (1.0 g, 10.0 mmol) was added dropwise to a mixture of acetonitrile (10.0 g) and 1,4-dibromobutane (13.1 g, 60.0 mmol). The mixture was then heated to 65 °C and stirred for 24 h to stop the reaction. A large amount of solvent was evaporated by rotary evaporation, and the crude product was precipitated with diethyl ether. It was further purified with anhydrous diethyl ether and dried under vacuum at room temperature for 24 h to obtain bromobutylpiperidine, with the structural formula shown in Formula 3. Formula 3 ; Step 2: In a 50 mL round-bottom flask, add 2.346 g (10 mmol) of p-terphenyl, 0.488 g (1 mmol) of 9,10-bis(1-naphthyl)anthracene, and 15 mL of anhydrous dichloromethane, then add 2 g (14 mmol) of indigo and mix thoroughly. After stirring at 0 °C for 30 min, first add 1.21 mL (16.2 mmol) of trifluoroacetic acid dropwise through a constant-pressure dropping funnel, followed by 14.4 mL (145.8 mmol) of trifluoromethanesulfonic acid dropwise. With the addition of trifluoromethanesulfonic acid, the turbid liquid changes from white to blue, and finally to a black viscous liquid. Throughout the polymerization process, the reaction vessel should be kept in an ice bath to limit the formation of byproducts. When the viscosity increases sufficiently to prevent magnetic stirring (approximately 6 h of reaction), the reaction is stopped.

[0029] After the reactions in steps 2 and 3 are complete, first slowly pour the reaction solution into 500 mL of deionized water. Then, crush the precipitated solid using a high-speed blender and pour it into 500-1000 mL of 0.5 M KOH aqueous solution to remove any residual acid on the surface. Next, pass the solution through hot isopropanol (at 60°C) containing 0.5 M KOH. o C) Treatment to remove as much acid as possible from the polymer, followed by hot water (temperature 60°C). o C) The copolymer was repeatedly washed with isopropanol until neutral and then dried in a vacuum oven at 80°C.

[0030] Step 4: The ionomer (1.314 g, 4.0 mmol) and bromobutylpiperidine (0.822 g, 8.0 mmol) were mixed in dimethyl sulfoxide (25.0 mL) and reacted at 85 °C for 48 h. After the reaction was complete, the reaction solution was dropped into ethyl acetate to precipitate the ionomer, washed several times with a mixture of water and ethanol, and then dried in a vacuum oven at 80 °C to obtain the ionomer. Step 5: Dissolve the ionomer in DMSO at 5% wt to obtain a polymer solution. Then, drop the polymer solution onto a polytetrafluoroethylene plate to form a film, and dry it at 60°C for 2 hours to prepare Br. - Type of anion exchange membrane.

[0031] Step 6: Take the obtained Br - The type anion exchange membrane was placed in a 1M potassium hydroxide solution and soaked at 60°C for 24 hours until the Br... - Completely exchanged for OH - Then, the residual potassium hydroxide was removed with deionized water to obtain OH as shown in Formula 2. - A high free volume anion exchange membrane, wherein x=10% and y=90%.

[0032] Example 2 A high free volume anion exchange membrane (PTID-15) is prepared by means of the following steps: the same as in Example 1, except that terphenyl (2.22 g, 9.5 mmol), 9,10-bis(1-naphthyl)anthracene (0.752 g, 1.5 mmol), indigo (2 g, 14 mmol), trifluoroacetic acid (1.21 mL, 16.2 mmol), and trifluoromethanesulfonic acid (14.4 mL, 145.8 mmol).

[0033] The OH prepared in this embodiment is shown in Formula 2. - A high free volume anion exchange membrane, wherein x=15% and y=85%.

[0034] Example 3 A high free volume anion exchange membrane (PTID-20) is prepared by means of the following steps: the same as in Example 1, except that terphenyl (2.15 g, 9 mmol), 9,10-bis(1-naphthyl)anthracene (1 g, 2 mmol), indigo (2 g, 14 mmol), trifluoroacetic acid (1.21 mL, 16.2 mmol), and trifluoromethanesulfonic acid (14.4 mL, 145.8 mmol).

[0035] The OH prepared in this embodiment is shown in Formula 2. -A high free volume anion exchange membrane, wherein x=20% and y=80%.

[0036] Comparative Example 1 Formula 4 ; An anion exchange membrane as shown in Formula 4; The preparation method includes the following steps: Same as Example 1, except that step 2 is as follows: Step 1: In a 50 mL round-bottom flask, add 2.7 g (11.6 mmol) of terphenyl and 15 mL of anhydrous dichloromethane, then add 2 g (14 mmol) of indigo and mix thoroughly. After stirring at 0 °C for 30 min, first add 1.21 mL (16.2 mmol) of trifluoroacetic acid dropwise through a constant-pressure dropping funnel, followed by 14.4 mL (145.8 mmol) of trifluoromethanesulfonic acid dropwise. With the addition of trifluoromethanesulfonic acid, the turbid liquid changes from white to blue, and finally becomes a black viscous liquid. Throughout the polymerization process, the reaction vessel should be kept in an ice bath to limit the formation of byproducts. When the viscosity increases sufficiently to prevent magnetic stirring (approximately 6 h of reaction), the reaction is stopped.

[0037] Comparative Example 2 Formula 5 ; Where x = 90%, y = 10%; An anion exchange membrane, as shown in Formula 5, is prepared by the following steps: Same as in Example 1, except that step 2 is as follows: In a 50 mL round-bottom flask, 2.415 g (10.5 mmol) of p-terphenyl, 0.385 g (1.16 mmol) of 9,10-diphenylanthracene, and 15 mL of anhydrous dichloromethane were added, followed by 2 g (14 mmol) of indigo and mixed thoroughly. After stirring at 0 °C for 30 min, trifluoroacetic acid (1.21 mL, 16.2 mmol) was added dropwise through a constant-pressure dropping funnel, followed by trifluoromethanesulfonic acid (14.4 mL, 145.8 mmol). With the addition of trifluoromethanesulfonic acid, the turbid liquid changed from white to blue, and finally to a black viscous liquid. Throughout the polymerization process, the reaction vessel was kept in an ice bath to limit the formation of byproducts. The reaction was stopped when the viscosity increased sufficiently to prevent magnetic stirring (approximately 6 h).

[0038] Example 1 The high free volume anion exchange membranes prepared in Examples 1-3 were subjected to 1H NMR spectroscopy scans, and the results are shown in the figure. Figure 2 ; from Figure 2It can be seen that the small peak at 11.0 ppm when the polymer is not ionized is attributed to hydrogen atoms on indigo. Furthermore, the number of aromatic hydrogen atoms at 7.0–8.0 ppm increases with the monomer content, demonstrating the successful introduction of the 9,10-bis(1-naphthyl)anthracene component. Additionally, a series of new signals appear in the NMR spectrum at 1.21–2.00 ppm; these new peaks are attributed to hydrogen atoms on the piperidine ring and the long-chain methylene group, indicating successful grafting of the side chain onto the polymer backbone. When the bromobutylpiperidine side chain is 100% grafted, the peak at around 10.0 ppm, originally attributed to hydrogen atoms on indigo, completely disappears.

[0039] Example of effect 2: The anion exchange membranes prepared in Examples 1-3 and Comparative Example 1 were tested for ion conductivity, tensile strength, water absorption, and swelling ratio. The results are shown in the figure. Figure 3 , 7 -8 and Table 1; The method for testing ionic conductivity involved cutting out a 1cm × 4cm sample and immersing it in a 1.0M KOH aqueous solution at room temperature for 12 hours to perform ion exchange. Subsequently, residual OH groups were washed with nitrogen-saturated deionized water. - The samples were sealed and stored to prevent carbon dioxide ingress. High free volume membrane samples with hydroxide ions as anions were analyzed using a CHI660C electrochemical instrument via a four-probe AC ​​impedance method to measure ionic conductivity, with a frequency range from 1 Hz to 1 × 10⁻⁶ Hz. The AC impedance measurement was performed in ultrapure water filled with nitrogen gas at Hz. - The formula for calculating electrical conductivity is as follows: ; Tensile strength: Samples with dimensions of 1cm × 4cm were cut out, and the mechanical properties of the membrane were determined using an Instron 5900 tensile testing machine.

[0040] Water absorption rate: First, accurately weigh the dried film sample. Then, under N2 protection, immerse the sample in deionized water at 30-80 ℃ for 24 h. After removal, quickly wipe off the surface moisture with a lint-free cloth and immediately measure the wet film mass. The wet film mass (WU) is calculated using the following formula:

[0041] ; Swelling Rate: The swelling rate (SR) test is calculated based on the difference in membrane length between wet and dry states. The sample is immersed in deionized water at 30-80 °C for 24 h. After removal, the surface moisture is quickly wiped away with a lint-free cloth, and the wet membrane length is immediately measured. SR is calculated using the following formula: ;

[0042] Table 1 .

[0043] As shown in Table 1, the higher the content of 9,10-bis(1-naphthyl)anthracene monomer, the more phenyl groups of biphenyl in the anthracene monomer, and the higher its ionic conductivity and tensile strength.

[0044] from Figure 3 , 7 Data from -8 shows that this invention greatly improves the water absorption rate of anion exchange membranes and reduces their swelling rate.

[0045] Example 3 The water flux performance of the membranes prepared in Examples 1-3 was tested at room temperature using a cross-flow filtration device (FHM-MF-LAB type). The membranes were cut into circular pieces with a diameter of 40 mm and then fixed in the membrane chamber of the cross-flow filtration device. The effective filtration area of ​​the membrane chamber was 7.06 cm². The transmembrane pressure was set to 1 bar (1 bar = 0.1 MPa), and the membrane was pre-pressurized with pure water for 1 hour. After the water flux of the membrane stabilized, the mass of the water permeated through the membrane was recorded in real time using an electronic balance and RsWeight software, and converted into the volume of permeated water. The results are shown below. Figure 4 ; like Figure 4 As shown, the water flux of the PTID-20 membrane in Example 3 increased to 2.231. The water flux of the PTID-10 membrane in Example 1 was only 1.267. This is attributed to the introduction of the large sterically hindered monomer 9,10-bis(1-naphthyl)anthracene unit in the PTID-20 membrane. These units increase the free volume within the membrane and form continuous water transport channels, thereby improving the water diffusion rate.

[0046] Example of effect 4 To investigate the reasons for the improved water transport capacity, we tested the changes in the interchain spacing of the membranes prepared in Examples 1-3 using X-ray diffraction (XRD). The results are shown below. Figure 5 ; Figure 5 The results show that all AEMs exhibit broad diffraction peaks, and with the introduction of 9,10-bis(1-naphthyl)anthracene monomer into the polymer backbone, the diffraction peaks... A significant change occurred, with the value gradually decreasing from 18.37 to 13.04, indicating an increase in the distance between molecular chain segments. The fundamental reason for this phenomenon is the introduction of rigid, twisted monomers, which lead to a looser packing of polymer chains, thereby increasing the free volume.

[0047] Example 5 To further investigate the effects of introducing sterically hindered monomers on the size of the intramembrane free volume and the distribution of water molecules in the water channels, we simulated the effects of PTID-20 in Example 3 and PTID-0 in Comparative Example 1 with and without sterically hindered monomers using hydration number and polymer backbone structure models. The results are shown in [Figure number missing]. Figure 6 ; like Figure 6 As shown, molecular dynamics simulations revealed the evolution of the water channel structure in PTID-0 and PTID-20 membrane materials: with the introduction of the 9,10-bis(1-naphthyl)anthracene monomer (from left to right), the water molecule distribution gradually changed from the disordered state of the PTID-0 membrane to the ordered continuous channel structure of the PTID-20 membrane. This structural transformation is mainly attributed to the steric hindrance effect of the 9,10-bis(1-naphthyl)anthracene monomer, whose twisted conformation significantly altered the polymer chain stacking pattern, forming a regular water transport path, which is crucial for efficient water transport under anhydrous cathode conditions. The corresponding free volume fraction (FFV) distribution is shown in the figure. Figure 6 As shown, the PTID-0 membrane exhibits a uniform but low FFV (14.14%), while the PTID-20 membrane, due to its rigid tortuous structure generating a significant steric hindrance effect, increases the FFV to 18.00%. This increase stems from providing more transport channels for water molecule diffusion and effectively promoting ion migration by expanding the ion conduction path. A schematic diagram of the efficient water transport channels in high free volume anion exchange membranes is shown below. Figure 1 Therefore, molecular simulations and experimental results together demonstrate the structure-activity relationship between the content of 9,10-bis(1-naphthyl)anthracene monomer and the mass transfer performance of membrane materials.

[0048] Example 6 The conductivity of high free volume anion exchange membranes as a function of the content of monomers with large steric hindrance is shown in the curve. Figure 7 As shown, a 1cm × 4cm sample was cut from the membrane and immersed in a 1.0 M KOH aqueous solution at room temperature for 12 hours for ion exchange. Subsequently, residual OH was washed with nitrogen-saturated deionized water. - The samples were sealed and stored to prevent carbon dioxide ingress. High free volume membrane samples with hydroxide ions as anions were analyzed using a CHI660C electrochemical instrument via a four-probe AC ​​impedance method to measure ionic conductivity, with a frequency range of 1 Hz to [missing value]. Hz, AC impedance measurements were performed in ultrapure water filled with nitrogen. OH- 360 Hz, AC impedance measurements were performed on three membranes with different proportions prepared in Examples 1-3. - The conductivity reaches 53-65 mS at 30 °C. At 80 ℃, it reaches 124.5-165.1. Of the three AEMs prepared in Examples 1-3, the one exhibiting the highest OH content at 80 °C was the 9,10-bis(1-naphthyl)anthracene monomer content reaching the PTID-20 percentage. - Electrical conductivity (165.1 mS) As temperature rises, OH − The migration speed is accelerated, and the differences between them become more obvious. The high conductivity of PTID-20 can be attributed to the following reasons: (1) The large-volume rigid twisting of 9,10-bis(1-naphthyl)anthracene on the main chain can weaken chain entanglement and increase free volume, thereby constructing a good microphase separation structure. (2) Introducing the sterically hindered 9,10-bis(1-naphthyl)anthracene monomer into the polymer main chain can effectively construct a continuous water transport channel, and significantly improve the ion conduction performance of the membrane by promoting the carrier migration mechanism.

[0049] Example 7 The mechanical properties of high-free-volume anion exchange membranes (Examples 1-3) containing varying proportions of 9,10-bis(1-naphthyl)anthracene monomer in the polymer backbone under halogen conditions are as follows: Figure 8 As shown; from Figure 8 It was found that the tensile strength of AEMs with different free volumes gradually increased with the increase of rigid 9,10-bis(1-naphthyl)anthracene monomer content (from 52.7 MPa to 77.5 MPa), while the elongation at break also increased to some extent (from 30% to 45%). The results indicate that the tensile strength was significantly improved due to the increase of rigid 9,10-bis(1-naphthyl)anthracene monomer content in the polymer chain, which may be due to the introduction of rigid monomers into the polymer backbone. In addition, the presence of large steric hindrance structures in the backbone effectively alleviated chain entanglement, thereby improving the elongation at break.

[0050] Example 8 Figure 9 The hydrogen permeability of PTID-x (x=10, 15, 20) membranes with different free volume sizes was revealed, which plays a crucial role in the safe operation and long-term stable operation of AEMWE.

[0051] like Figure 9 As shown, the membranes prepared in Examples 1-3 all exhibit low hydrogen permeability (all <20 Barrer, where 1 Barrer = ... The permeability is significantly lower than that of commercial Nafion membranes (>60 Barrer). Among them, PTID-20 exhibits the highest gas permeability in the dry state (13.58 Barrer), which is greater than PTID-10 (9.38 Barrer). This is due to the presence of large steric hindrance units between polymer chain segments, which makes the molecular chain segments loosely packed and increases the free volume inside the membrane. However, all of them can meet the requirements of practical use.

[0052] Example 9 The voltammetric polarization curves of high free volume anion exchange membranes in water electrolysis devices are shown below. Figure 10 As shown, the single-cell electrolysis of water uses Pt-Ru / C as the negative electrode catalyst and a (NiFeCo) non-precious metal catalyst as the positive electrode. The catalyst is prepared by adding 5 mL of 1.0 MkOH solution preheated at 60°C. Under the given flow rate, the three types of AEMs prepared in Examples 1-3 were subjected to a potentiostat at different temperatures. The rate of change linearly scanned the battery voltage from 1.2 V to 2.1 V. The resulting polarization curve is shown below. Figure 10 As shown;

[0053] from Figure 10 It can be seen that the current density of AEMWE based on the PTID-20 film reaches [value missing] at 2.0V and 80°C. These are based on PTID-15 (6.9) ) and PTID-10 (5.6 The current density of PTID-20 in the water electrolyzer is 1.16 times and 1.43 times that of the anhydrous cathode mode. The superior performance of PTID-20 in the anhydrous cathode mode can be attributed to the presence of high free volume within its membrane, which forms directional water transport channels, thereby improving its electrolysis efficiency.

[0054] Example 10 The in-situ durability curve of the high free volume anion exchange membrane in a water electrolysis device under 1 M KOH electrolyte is shown below. Figure 11 As shown; The PTID-20 anion exchange membrane of Example 3 was subjected to a temperature of 0.5... Long-term stability tests for water electrolysis were conducted by passing a 1 M KOH solution electrolyte under constant current. After 550 hours of operation, the voltage of the electrolyzer slowly increased from 1.75 V to 1.9 V, with a decay rate of [missing value]. Furthermore, the membrane remained intact after testing, demonstrating its broad potential in water electrolysis applications.

[0055] The embodiments described above are merely preferred embodiments of the present invention, and not an exhaustive list of all possible implementations of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A high free volume type anion exchange membrane, characterized by, The ionomer comprises repeating units as shown in Formula 1: Formula 1 ； wherein x and y are molar percentages relative to the repeating units; x + y = 100%; m is 0, 1 or 2; A - selected from I - , Br - , Cl - , SCN - , , OH - ; Ar1 is selected from fused benzene compounds; Ar2 is selected from biaryl compounds.

2. The high free volume anion exchange membrane according to claim 1, wherein Ar1is selected from any one of , , , , .

3. The high free volume anion exchange membrane according to claim 1, wherein the ionomer comprises the following steps: Ar2is selected from any one of , , , , , .

4. A method for producing the high free volume anion exchange membrane according to any one of claims 1 to 3, characterized by, Step 1: adding methylpiperidine and 1,4-dibromobutane into a first solvent, and reacting at 60-70°C for 20-28 h to obtain a bromobutylpiperidine ionic liquid; Step 2: adding biaryl compounds, fused benzene compounds and indigo into a second solvent, and then adding trifluoroacetic acid and trifluoromethanesulfonic acid dropwise at 0°C, respectively, and reacting for 5-7 h to end the reaction to obtain a copolymer; Step 3: adding the copolymer obtained in Step 2 and the bromobutylpiperidine ionic liquid obtained in Step 1 into a second solvent, and reacting at 82-88°C for 40-56 h to end the reaction, and then dropping the reaction liquid into a third solvent to precipitate the polymer, and washing the polymer several times, and drying to obtain an ionomer; Step 4: adding the ionomer into a second solvent to prepare a polymer solution, and then casting into a film, and drying to obtain a high free volume anion exchange membrane.

5. The preparation method of the high free volume anion exchange membrane according to claim 4, wherein after the reaction in Step 2 is ended, post-treatment is further needed, and the post-treatment comprises: pouring the reaction liquid for producing the copolymer into deionized water to precipitate a solid, and then cutting the solid into small pieces, and then washing with an alkali-containing aqueous solution and an alkali-containing isopropanol to remove acid, and then washing until neutral, and then drying to obtain the copolymer.

6. The preparation method of the high free volume anion exchange membrane according to claim 4, wherein in Step 1, the molar ratio of 1,4-dibromobutane to methylpiperidine is 6-10:1; in Step 2, the molar ratio of the total amount of biaryl compounds and fused benzene compounds, indigo, trifluoroacetic acid and trifluoromethanesulfonic acid is 1:1.1-1.3:0.5-1.5:5-15; wherein the biaryl compounds account for 80-90% of the total molar amount of the biaryl compounds and the fused benzene compounds, and the fused benzene compounds account for 10-20% of the total molar amount of the biaryl compounds and the fused benzene compounds.

7. The preparation method of the high free volume anion exchange membrane according to claim 4, wherein in Step 4, the time for casting into a film is ≤3 h, and the temperature for casting into a film is 50-90°C.

8. The preparation method of the high free volume anion exchange membrane according to claim 4, wherein the first solvent is acetonitrile; the second solvent is dimethyl sulfoxide; the third solvent is ethyl acetate; the alkali in the alkali-containing aqueous solution and the alkali-containing isopropanol is KOH. The high free volume anion exchange membrane according to claim 1 is obtained by soaking in an alkaline solution.

10. Use of the high free volume anion exchange membrane according to any one of claims 1-3 or the alkaline high free volume anion exchange membrane according to claim 9 in electrolysis of water. ​ ​ ​ 9. A basic high-free-volume type anion exchange membrane, characterized by, ​ ​

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