A method for preparing a composite polymer alkaline anion exchange membrane and applications thereof

Abstract

This invention provides a method for preparing a composite polymer basic anion exchange membrane and its application. The method includes the following steps: (1) reacting a first polymer containing aryl groups, a piperidinone compound, a catalyst, and a first solvent to obtain a precursor material; reacting the precursor material, iodomethane, and a second solvent to obtain a polymer material through anion exchange; (2) mixing the polymer material obtained in step (1) with a third solvent to obtain a polymer solution; and combining the polymer solution with a substrate to form a membrane to obtain the composite polymer basic anion exchange membrane. This invention provides a simple and mass-producible method for preparing a composite polymer basic anion exchange membrane, which can significantly improve the long-term high-performance hydrogen production of basic anion exchange membrane electrolyzers.

Description

Technical Field

[0001] This invention belongs to the field of anion exchange membrane material technology, specifically relating to a method for preparing a composite polymer basic anion exchange membrane and its application. Background Technology

[0002] As a key component of alkaline anion exchange membrane electrolyzers, alkaline anion exchange membranes not only isolate oxidants and reductants but also facilitate ion conduction. However, most existing alkaline anion exchange membranes (homogeneous membranes) suffer from high ion exchange capacity, leading to a significant decrease in mechanical properties when water content is too high, making them prone to rupture under high pressure. Furthermore, they exhibit significant swelling, causing substantial changes in membrane size, resulting in pinholes in the catalyst layer, and even separation from the membrane, severely impacting the overall performance of the electrolyzer.

[0003] Currently, researchers are using methods such as cross-linking the main chain or chemically cross-linking functional groups to improve the mechanical strength of basic anion exchange membranes. While these methods have improved the mechanical strength of basic anion exchange membranes to some extent, chemical cross-linking can sometimes reduce the ion exchange capacity or conductivity of the membrane, and can also reduce the membrane's toughness, making it brittle. Furthermore, some chemical cross-linking methods are difficult to mass-produce, creating a bottleneck for the practical application of basic anion exchange membranes.

[0004] Therefore, there is an urgent need to develop an effective solution to optimize the mechanical properties and dimensional stability of alkaline anion exchange membranes, so that they can simultaneously possess good ion exchange functions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing composite polymer basic anion exchange membranes and their applications. Given the low mechanical properties, poor dimensional stability, and uncertainties and complexities in crosslinking methods of most basic anion exchange membranes (homogeneous membranes), the present invention provides a simple and mass-producible method for preparing composite polymer basic anion exchange membranes, thereby significantly improving the long-term high-performance hydrogen production of basic anion exchange membrane electrolyzers.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a composite polymer basic anion exchange membrane, the method comprising the following steps:

[0008] (1) A first polymer containing an aryl group, a piperidinone compound, a catalyst and a first solvent are reacted in a first reaction to obtain a precursor material; the precursor material, iodomethane and a second solvent are reacted in a second reaction, and finally anion exchange is performed to obtain a polymer material;

[0009] (2) The polymer material obtained in step (1) is mixed with a third solvent to obtain a polymer solution; the polymer solution is then combined with a substrate to form a composite film to obtain the composite polymer alkaline anion exchange membrane.

[0010] This invention utilizes the chemical crosslinking of piperidine and aryl groups, combined with the excellent rigidity and structural stability of the first polymer containing aryl groups, thereby improving the heat resistance and chemical stability of the precursor material. Furthermore, the precursor material, methyl bromide, and a second solvent are subjected to a quaternization reaction to obtain a polymer with high ion exchange capacity and high ionic conductivity. Finally, the polymer material is composited with a substrate to form a film. The excellent strength and dimensional stability of the substrate itself are combined to improve the mechanical strength and dimensional stability of the film, ultimately resulting in a composite polymer basic anion exchange membrane with good dimensional stability, high mechanical strength, high ion exchange capacity, high ionic conductivity, and excellent thermal and chemical stability.

[0011] First, the preparation process provided by this invention is simple and easy to mass-produce. Second, the prepared composite polymer alkaline anion exchange membrane has a conductivity greater than 80 mS / cm in 1 mol KOH electrolyte at 60℃, which enables high-performance hydrogen production in alkaline anion exchange membrane electrolyzers. Finally, the prepared composite polymer alkaline anion exchange membrane has excellent mechanical stability, dimensional stability and electrochemical stability, which can meet the requirements of hydrogen production in alkaline anion exchange membrane electrolyzers under long-term high-pressure conditions.

[0012] Preferably, the first polymer containing aryl groups in step (1) includes any one or a combination of at least two of biphenyl, p-terphenyl, or diphenylmethane.

[0013] Preferably, the piperidone compound in step (1) includes any one or a combination of at least two of N-methyl-4-piperidone, N-propyl-4-piperidone, N-isopropyl-4-piperidone or 1-cyclohexyl-4-piperidone.

[0014] Preferably, the molar ratio of the first polymer containing the aryl group to the piperidinone compound in step (1) is 1:(0.5-3), for example, it can be 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc.

[0015] In this invention, the molecular weight of the obtained linear polymer is controlled by adjusting the molar ratio of the first polymer containing aryl groups to the piperidinone compound. If the ratio is too low, the reaction will stop at the oligomer stage, and the molecular weight cannot be increased further, resulting in a low molecular weight polymer and a low yield. Conversely, if the ratio is too high, the local molecular weight will increase dramatically, resulting in the encapsulation of unreacted monomers and a large amount of monomer residue.

[0016] Preferably, the catalyst in step (1) comprises a combination of at least two of methanesulfonic acid, trifluoropropionic acid, pentafluoropropionic acid, dichloromethane, trifluoromethanesulfonic acid, pentafluoroacetic acid, or trifluoroacetic acid.

[0017] Preferably, the catalyst in step (1) comprises a combination of pentafluoropropionic acid and trifluoromethanesulfonic acid.

[0018] Preferably, the volume of the pentafluoropropionic acid is 5 mL.

[0019] Preferably, the volume of the trifluoromethanesulfonic acid is 50 mL.

[0020] Preferably, the first solvent in step (1) includes any one or a combination of at least two of toluene, chloromethane, chloroform or tetrachloroethane.

[0021] Preferably, the temperature of the first reaction in step (1) is 2°C and the time is 10h.

[0022] Preferably, the second solvent in step (1) includes any one or a combination of at least two of dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, or N-methylpyrrolidone.

[0023] Preferably, the temperature of the secondary reaction in step (1) is 70°C and the time is 12h.

[0024] Preferably, the mass ratio of the polymer material to the volume ratio of the third solvent in step (2) is 1g:(1-10)mL, more preferably 1g:(3-5)mL, for example, 1g:1mL, 1g:2mL, 1g:3mL, 1g:4mL, 1g:5mL, 1g:6mL, 1g:7mL, 1g:8mL, 1g:9mL, 1g:10mL, etc.

[0025] In this invention, by adjusting the mass ratio of the polymer material to the volume ratio of the third solvent, the polymer solution achieves a suitable viscosity and solid content. If the ratio is too low, a low viscosity and low solid content solution will be obtained, resulting in poor coating penetration and poor film formation. Conversely, a high viscosity and high solid content solution will be obtained, resulting in ineffective wetting of the substrate and poor film formation.

[0026] Preferably, the third solvent in step (2) includes dimethyl sulfoxide and / or deionized water.

[0027] Preferably, step (2) of compounding the polymer solution with the substrate to form a film includes the following steps: laying the substrate flat on a fixing device, then coating the polymer solution onto the surface of the substrate, and drying to obtain the composite polymer alkaline anion exchange membrane.

[0028] Preferably, the substrate in step (2) includes any one of polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), woven fabric or nonwoven fabric.

[0029] Preferably, the fixing device includes any one of a tension fixing device, an adsorption fixing device, or a clamp fixing device.

[0030] Preferably, the coating method includes scraping.

[0031] Preferably, the drying method includes any one of heating drying, microwave drying, or ultraviolet drying.

[0032] Preferably, the heating and drying temperature is 60 to 100°C, for example, 60°C, 70°C, 80°C, 90°C, 100°C, etc.

[0033] In a second aspect, the present invention provides a composite polymer basic anion exchange membrane, which is prepared by the method for preparing a composite polymer basic anion exchange membrane according to the first aspect.

[0034] Thirdly, the present invention provides a hydrogen-oxygen composite polymer basic anion exchange membrane, which is prepared by immersing the composite polymer basic anion exchange membrane according to the second aspect in an alkaline solution.

[0035] Preferably, the alkaline solution includes a sodium hydroxide solution or a potassium hydroxide solution.

[0036] Preferably, the concentration of the alkaline solution is 1 to 2 mol / L, for example, it can be 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, etc.

[0037] Preferably, the soaking temperature is 60-90℃, for example, 60℃, 70℃, 80℃, 90℃, etc.; the soaking time is 24-48h, for example, 24h, 28h, 30h, 32h, 36h, 40h, 42h, 44h, 48h, etc.

[0038] Preferably, the conductivity of the hydrogen-oxygen composite polymer alkaline anion exchange membrane is greater than 80 mS / cm, for example, it can be 82 mS / cm, 85 mS / cm, 90 mS / cm, 100 mS / cm, 110 mS / cm, etc.; the elongation at break is greater than 20%, for example, it can be 25%, 35%, 45%, 55%, 65%, 75%, etc.; and the tensile strength is greater than 20 MPa, for example, it can be 25 MPa, 35 MPa, 45 MPa, 55 MPa, 65 MPa, 75 MPa, 85 MPa, etc.

[0039] It should be noted that the conductivity in this invention refers to the conductivity obtained by testing in an electrolyte of 1 mol KOH at 60°C.

[0040] The hydrogen-oxygen composite polymer alkaline anion exchange membrane prepared by this invention has good ion conductivity, mechanical strength and flexibility.

[0041] Fourthly, the present invention provides an electrolyte membrane comprising the hydrogen-oxygen composite polymer basic anion exchange membrane according to the third aspect.

[0042] Fifthly, the present invention provides an electrolytic cell comprising an electrolyte membrane according to the fourth aspect.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] This invention provides a method for preparing a composite polymer basic anion exchange membrane. First, the preparation process is simple and easy to mass-produce. Second, the prepared composite polymer basic anion exchange membrane exhibits a conductivity greater than 80 mS / cm in 1 mol KOH electrolyte at 60℃, enabling high-performance hydrogen production in a basic anion exchange membrane electrolyzer. Finally, the prepared composite polymer basic anion exchange membrane possesses excellent mechanical stability, dimensional stability, and electrochemical stability, meeting the requirements for long-term high-pressure hydrogen production in a basic anion exchange membrane electrolyzer. Attached Figure Description

[0045] Figure 1 Mechanical property diagrams of the substrate, composite polymer alkaline anion exchange membrane, and homogeneous alkaline anion exchange membrane provided in Example 1;

[0046] Figure 2 The polarization curves of the electrolyzer assembled from the homogeneous basic anion exchange membrane and the composite polymer basic anion exchange membrane provided in Example 1 are shown.

[0047] Figure 3The stability performance diagram of the electrolyzer assembled from the homogeneous alkaline anion exchange membrane and the composite polymer alkaline anion exchange membrane provided in Example 1. Detailed Implementation

[0048] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be considered as specific limitations thereof.

[0049] Example 1

[0050] This embodiment provides a method for preparing a composite polymer basic anion exchange membrane, the method comprising the following steps:

[0051] (1) Biphenyl, N-methyl-4-piperidinone, 5 mL pentafluoropropionic acid, 50 mL trifluoromethanesulfonic acid and toluene were reacted at 2 °C for 10 h, wherein the molar ratio of biphenyl to N-methyl-4-piperidinone was 1:2 to obtain the precursor material. Then the precursor material, iodomethane and N,N-dimethylacetamide were reacted at 70 °C for 12 h to generate quaternary ammonium salt. Finally, hydroxide ion exchange was performed to obtain the polymer material.

[0052] (2) The polymer material obtained in step (1) is mixed with dimethyl sulfoxide, wherein the mass ratio of polymer to volume ratio of dimethyl sulfoxide is 1g:4mL to obtain a polymer solution. The PTFE substrate is laid flat on the stretching and fixing device, and then the polymer solution is coated and filled on both sides using a scraper. After heating and drying at 80°C, the composite polymer alkaline anion exchange membrane is obtained.

[0053] This embodiment also provides a method for preparing a chlorine-type composite polymer basic anion exchange membrane and a hydroxide-type composite polymer basic anion exchange membrane, which includes the following steps:

[0054] The composite polymer alkaline anion exchange membrane was prepared by immersing it in a 1.0 mol / L potassium hydroxide solution or a 1.0 mol / L sodium hydroxide solution at a temperature of 80°C for 24 hours, with the alkaline solution being replaced every 8 hours.

[0055] Figure 1The results show that the tensile strength of the chloride-type composite polymer basic anion exchange membrane is as high as 31 MPa, which is about 7 MPa higher than that of the chloride-type homogeneous basic anion exchange membrane. In practical applications, the basic anion exchange membrane exists in the hydroxide form. Although the tensile strength of the composite polymer basic anion exchange membrane and the homogeneous basic anion exchange membrane is reduced, the tensile strength of the composite polymer basic anion exchange membrane is significantly better than that of the homogeneous basic anion exchange membrane. This proves that the composite polymer basic anion exchange membrane can withstand higher gas pressure environments in electrolytic cell applications.

[0056] Example 2

[0057] This embodiment provides a method for preparing a composite polymer basic anion exchange membrane, the method comprising the following steps:

[0058] (1) Biphenyl, N-methyl-4-piperidinone, 5 mL pentafluoropropionic acid, 50 mL trifluoromethanesulfonic acid and toluene were reacted at 2 °C for 10 h, wherein the molar ratio of biphenyl to N-methyl-4-piperidinone was 1:2 to obtain the precursor material. Then the precursor material, iodomethane and N,N-dimethylacetamide were reacted at 70 °C for 12 h to generate quaternary ammonium salt. Finally, hydroxide ion exchange was performed to obtain the polymer material.

[0059] (2) The polymer material obtained in step (1) is mixed with dimethyl sulfoxide, wherein the mass ratio of polymer to volume ratio of dimethyl sulfoxide is 1g:3mL to obtain a polymer solution. The PTFE substrate is laid flat on the stretching and fixing device, and then the polymer solution is coated and filled on both sides using a scraper. After heating and drying at 80°C, the composite polymer alkaline anion exchange membrane is obtained.

[0060] Example 3

[0061] This embodiment provides a method for preparing a composite polymer basic anion exchange membrane, the method comprising the following steps:

[0062] (1) Biphenyl, N-methyl-4-piperidinone, 5 mL pentafluoropropionic acid, 50 mL trifluoromethanesulfonic acid and toluene were reacted at 2 °C for 10 h, wherein the molar ratio of biphenyl to N-methyl-4-piperidinone was 1:2 to obtain the precursor material. Then the precursor material, iodomethane and N,N-dimethylacetamide were reacted at 70 °C for 12 h to generate quaternary ammonium salt. Finally, hydroxide ion exchange was performed to obtain the polymer material.

[0063] (2) The polymer material obtained in step (1) is mixed with dimethyl sulfoxide, wherein the mass ratio of polymer to volume ratio of dimethyl sulfoxide is 1g:5mL to obtain a polymer solution. The PTFE substrate is laid flat on the stretching and fixing device, and then the polymer solution is coated and filled on both sides using a scraper. After heating and drying at 80°C, the composite polymer alkaline anion exchange membrane is obtained.

[0064] Example 4

[0065] This embodiment provides a method for preparing a composite polymer basic anion exchange membrane, the method comprising the following steps:

[0066] (1) Triphenyl, N-methyl-4-piperidinone, 5 mL pentafluoropropionic acid, 50 mL trifluoromethanesulfonic acid and toluene were reacted at 2 °C for 10 h, wherein the molar ratio of terphenyl to N-methyl-4-piperidinone was 1:2 to obtain a precursor material. Then, the precursor material, iodomethane and N,N-dimethylacetamide were reacted at 70 °C for 12 h to generate a quaternary ammonium salt. Finally, hydroxide ion exchange was performed to obtain a polymer material.

[0067] (2) The polymer material obtained in step (1) is mixed with dimethyl sulfoxide, wherein the mass ratio of polymer to volume ratio of dimethyl sulfoxide is 1g:1mL to obtain a polymer solution. The PTFE substrate is laid flat on the stretching and fixing device, and then the polymer solution is coated and filled on both sides using a scraper. After heating and drying at 60°C, the composite polymer alkaline anion exchange membrane is obtained.

[0068] Example 5

[0069] This embodiment provides a method for preparing a composite polymer basic anion exchange membrane, the method comprising the following steps:

[0070] (1) Triphenyl, N-methyl-4-piperidinone, 5 mL pentafluoropropionic acid, 50 mL trifluoromethanesulfonic acid and toluene were reacted at 2 °C for 10 h, wherein the molar ratio of terphenyl to N-methyl-4-piperidinone was 1:2 to obtain a precursor material. Then, the precursor material, iodomethane and N,N-dimethylacetamide were reacted at 70 °C for 12 h to generate a quaternary ammonium salt. Finally, hydroxide ion exchange was performed to obtain a polymer material.

[0071] (2) The polymer material obtained in step (1) is mixed with dimethyl sulfoxide, wherein the mass ratio of polymer to volume ratio of dimethyl sulfoxide is 1g:10mL to obtain a polymer solution. The PTFE substrate is laid flat on the stretching and fixing device, and then the polymer solution is coated and filled on both sides using a scraper. After heating and drying at 100°C, the composite polymer alkaline anion exchange membrane is obtained.

[0072] Example 6

[0073] The difference between this embodiment and Example 1 is that the molar ratio of biphenyl to N-methyl-4-piperidone is 1:0.5, while all other aspects are the same as in Example 1.

[0074] Example 7

[0075] The difference between this embodiment and Example 1 is that the molar ratio of biphenyl to N-methyl-4-piperidone is 1:3, while all other aspects are the same as in Example 1.

[0076] Example 8

[0077] The difference between this embodiment and Example 1 is that the mass ratio of the polymer to the volume ratio of dimethyl sulfoxide in step (2) is 1 g: 0.5 mL, while all other aspects are the same as in Example 1.

[0078] Example 9

[0079] The difference between this embodiment and Example 1 is that the mass ratio of the polymer to the volume ratio of dimethyl sulfoxide in step (2) is 1g:20mL, while all other aspects are the same as in Example 1.

[0080] Example 10

[0081] The difference between this embodiment and Embodiment 1 is that biphenyl in step (1) is replaced with diphenylmethane, while everything else is the same as in Embodiment 1.

[0082] Comparative Example 1

[0083] The difference between this comparative example and Example 1 is that the polymer solution obtained in step (2) is directly cast into a film to obtain a homogeneous film. Everything else is the same as in Example 1.

[0084] Comparative Example 2

[0085] The difference between this comparative example and Example 1 is that biphenyl in step (1) is replaced with 9,9-dimethylfluorene, while everything else is the same as in Example 1.

[0086] Test conditions

[0087] The composite polymer alkaline anion exchange membranes provided in Examples 1 to 10 and Comparative Examples 1 to 2 were subjected to performance testing, and the testing methods are as follows:

[0088] (1) Ion exchange capacity:

[0089] The membrane sample was cut into 50×50mm pieces and immersed in a 1mol / L potassium hydroxide solution at 80℃ for 24 hours to exchange chloride ions for hydroxide ions, obtaining a hydroxide-type membrane. This hydroxide-type membrane was then immersed in a 1mol / L NaCl solution at 60℃ for 48 hours to undergo ion exchange, obtaining a chloride-type membrane. The chloride-type membrane was thoroughly washed with deionized water to ensure complete removal of adsorbed NaCl. The surface moisture of the chloride-type membrane was blotted dry with filter paper, and it was then immersed in 50mL of a 0.1mol / L NaNO3 solution at 60℃ for 48 hours to allow complete exchange of chloride ions from the membrane into the NaNO3 solution. The chloride ions exchanged in the NaNO3 solution are the anions to be measured in the membrane. Chloride ion content in the titration membrane: Add 10 mL of NaNO3 solution, which has been thoroughly soaked in the chloride form membrane, to an Erlenmeyer flask. Simultaneously add two drops of K2CrO4 as an indicator. Titrate with a standardized 0.01 mol / L AgNO3 solution until a brick-red precipitate forms. Record the volume of AgNO3 solution consumed, denoted as V. AgNO3 Perform three parallel titrations and take the average value to calculate the chloride ion content in the membrane. Finally, remove the membrane, wash it thoroughly with deionized water, dry it completely in an oven, and quickly weigh the dry membrane, recording the mass as m. dry The ion exchange capacity of an alkaline membrane can be calculated using the formula: IEC = 5 × C AgNO3 ×V AgNO3 / m dry In the formula: IEC is the ion exchange capacity of the membrane, with units of mol / g; C AgNO3 V represents the concentration of the standardized AgNO3 solution, in mol / L, calculated as the average of three titrations. AgNO3 The volume of AgNO3 solution consumed in the titration is expressed in liters (L), and is the average of the volumes used in three titrations; m dry The mass of the dried membrane after titration is expressed in grams.

[0090] (2) Thermal shrinkage rate:

[0091] Cut the sample into 50×50mm pieces using a mold, and take three parallel samples, marking them horizontally and vertically. Place a stainless steel plate and two sheets of quantitative filter paper in the middle of an oven, and maintain the temperature at 90℃. Lay the sample flat on the quantitative filter paper on the stainless steel plate in the middle of the oven, and then press it down with another sheet of quantitative filter paper, maintaining the temperature at 90℃ for 2 hours. Remove the sample and allow it to return to room temperature. Measure the horizontal and vertical dimensions L of the sample using a ruler and record the data. The thermal shrinkage rate of the film can be calculated using the formula: ΔL=(L0-L) / L0×100%, where: ΔL is the thermal shrinkage rate of the film, in %; L0 is the initial horizontal (vertical) length, in mm; and L is the horizontal (vertical) length after heat treatment, in mm.

[0092] (3) Ionic conductivity:

[0093] A 1.0 cm × (5.0 ± 0.5) cm chloride-form membrane was cut and immersed in a 1 mol / L potassium hydroxide solution at 80 °C for 24 h to exchange chloride ions for hydroxide ions, resulting in a hydroxyl-form membrane. Before testing, the free alkali on the membrane surface was washed away, and the membrane sample was stored in water. The membrane sample was then removed from the water and fixed in a conductivity testing device. A constant current pre-electrolysis was performed for a period of time (the current and electrolysis time were set according to the membrane's condition) to minimize the influence of carbonation. The gas flow rate, humidifier temperature, and electrolytic cell temperature were set. After the temperature reached the set value, the impedance spectrum of the sample was measured using an electrochemical workstation under conditions of a frequency range of 0.1 Hz to 1 MHz and a perturbation current of 1 mA. In the measured impedance spectrum, the impedance value of the membrane sample is read from the intersection of the low-frequency part of the spectrum with the real axis. The ionic conductivity of the membrane can be calculated according to the formula: σ=l / (a×b×R), where: σ is the ionic conductivity of the membrane, in s / cm; l is the distance between electrodes, in cm; a is the width of the membrane, in cm; b is the thickness of the membrane, in cm; and R is the measured impedance of the membrane, in Ω.

[0094] (4) Tensile strength and elongation at break:

[0095] Membrane samples are cut bidirectionally along the material's length (X-axis) and width (Y-axis), using a die to cut them into dumbbell shapes, ensuring smooth, unblemished edges. The samples are clamped in the testing fixture, ensuring the longitudinal axis of the sample and the center line connecting the upper and lower fixtures are roughly aligned. The samples are initially clamped along the clamping line, and then the clamping angle is adjusted using prestress to ensure the sample is flattened. The testing software is opened, and the test method is selected: "Tension." Generally, a speed of 50 mm / min or 100 mm / min is used. Relevant parameters (thickness, width, effective gauge length) are entered, and the test is started. The maximum tensile force F, tensile strength, and corresponding displacement ΔL are recorded. Based on the measured tensile curve, the required breaking tensile displacement and gauge length are read. The elongation at break of the membrane is calculated using the formula: ε = ΔL / L × 100%, where: ε is the elongation at break (%); ΔL is the breaking tensile displacement (mm); and L is the gauge length (mm).

[0096] (5) Water absorption rate:

[0097] The membrane sample was cut into 50×50mm pieces and immersed in a 1mol / L potassium hydroxide solution at 80℃ for 24 hours to exchange chloride ions for hydroxide ions in the membrane, obtaining a hydroxyl-type membrane. The free alkali on the obtained hydroxyl-type membrane was washed off with deionized water, then immersed in deionized water and placed at 80℃ for 2 hours to allow the membrane to fully absorb water. After removing the membrane and blotting the surface moisture with filter paper, the membrane was immediately weighed on an analytical balance, and the mass was recorded as W.wet Finally, the wet membrane was placed in an oven at 80°C for 24 hours to ensure it was fully dried, and the mass of the dried membrane was recorded as W. dry The method for calculating water content is as follows: WU = (W wet -W dry ) / W dry ×100%, where: WU is the water content of the membrane, in %; W wet The mass of the wet membrane (hydroxyl-hydrogen type) is expressed in grams (g); W dry This represents the mass of the dry membrane (hydrogen-oxygen type), expressed in grams.

[0098] (6) Swelling rate:

[0099] A strip of length × width = 40mm × 20mm was cut parallel to the membrane roll axis as a test strip for the transverse dimensional change rate; a strip of length × width = 40mm × 20mm was cut perpendicular to the membrane roll axis as a test strip for the longitudinal dimensional change rate. The lengths of the dry membrane (chlorine form) in both linear directions were measured with a ruler and denoted as l. dry Simultaneously, the thickness of the film is measured using a thickness gauge and recorded as d. dry Following the ion exchange procedure described in (5) above, a hydroxide-type membrane was obtained. The free alkali on the hydroxide-type membrane was washed away with deionized water, then immersed in deionized water and placed in an 80°C constant temperature water bath and room temperature pure water for at least 2 hours to allow the membrane to fully swell. After removal, the length and thickness of all membranes after swelling were measured using a ruler and a thickness gauge, and recorded as l. wet and d wet The changes in the transverse and longitudinal lengths of the alkaline membrane represent the transverse (longitudinal) swelling (in-plane SD), while the changes in membrane thickness represent the Z-axis swelling (through-plane SD). The calculation methods for both are as follows: SD in-plane =(l wet -l dry ) / l dry *100%, SD through-plane =(l wet -l dry ) / l dry *100%, where: SD in-plane and SD through-plane These represent the lateral and longitudinal swelling rates of the membrane, respectively, in %; dry and l wet d represents the lengths of the membrane in its dry and wet states, respectively, in mm; dry and d wet These are the thicknesses of the membrane in its dry and wet states, respectively, in μm.

[0100] The electrolyzers assembled from the composite polymer alkaline anion exchange membranes provided in Examples 1 to 10 and Comparative Examples 1 to 2 were subjected to performance testing, and the testing methods are as follows:

[0101] The ohmic impedance and polarization curves of the alkaline membrane in a Ni-Ni catalytic system at 1M KOH were tested.

[0102] The test results are shown in Table 1:

[0103] Table 1

[0104]

[0105]

[0106] Note: The tensile strength is the result of the test after alkali replacement treatment, i.e., the hydrogen-oxygen type membrane.

[0107] As can be seen from Table 1, based on the above test results, Example 1 is the preferred technical solution. Figure 2 This indicates that the assembled electrolytic cell has relatively small polarization. Figure 3 This indicates that the electrolytic cell assembled therefrom has good stability, therefore Example 1 has good overall performance. Firstly, by adjusting the molar ratio of biphenyl to N-methyl-4-piperidinone, the molecular weight of the obtained linear polymer was controlled. If the ratio was too low, the reaction would stop at the oligomer stage, and the molecular weight could not be increased further, resulting in a low molecular weight polymer and a low yield of organic matter. Conversely, if the ratio was too high, the local molecular weight would increase dramatically, causing unreacted monomers to be encapsulated, resulting in a large amount of monomer residue. Both situations ultimately led to low ion exchange capacity, ionic conductivity, and corresponding water content of the film, resulting in poor overall performance. Secondly, by adjusting the mass of the polymer and the volume ratio of dimethyl sulfoxide, the polymer solution could achieve suitable viscosity and solid content. If the ratio was too low, a low viscosity and low solid content solution would be obtained, while if the ratio was too high, a high viscosity and high solid content solution would be obtained, resulting in an inability to effectively wet the substrate. Both situations ultimately led to poor mechanical properties of the film. Finally, Comparative Example 1 and other examples show that after the polymer solution and the substrate were combined to form a film, the tensile strength and dimensional stability of the composite film in the hydroxyl form were significantly better than the corresponding performance parameters of the homogeneous film, indicating that this method can effectively improve the mechanical properties of the film.

[0108] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a hydrogen- oxygen type composite polymer alkaline anion exchange membrane, characterized by, The method includes the following steps: (1) A precursor material is obtained by reacting biphenyl, piperidone compounds, catalyst and first solvent in a first reaction; the precursor material, iodomethane and second solvent are reacted in a second reaction, and finally anion exchange is carried out to obtain polymer material; (2) The polymer material obtained in step (1) is mixed with the third solvent to obtain a polymer solution; the substrate is laid flat on the fixing device, and then the polymer solution is coated on the surface of the substrate. After drying, a composite polymer alkaline anion exchange membrane is obtained; the composite polymer alkaline anion exchange membrane is immersed in an alkaline solution to obtain the hydroxide-type composite polymer alkaline anion exchange membrane. The molar ratio of biphenyl to piperidone compounds in step (1) is 1:(2-2.5); The substrate mentioned in step (2) is polytetrafluoroethylene; the alkaline solution includes sodium hydroxide solution or potassium hydroxide solution with a concentration of 1-2 mol / L; the soaking temperature is 60-90℃ and the soaking time is 24-48h; The mass ratio of the polymer material to the volume ratio of the third solvent in step (2) is 1 g: (4-5) mL.

2. The method of claim 1, wherein, The piperidone compounds mentioned in step (1) include any one or a combination of at least two of N-methyl-4-piperidinone, N-propyl-4-piperidinone, N-isopropyl-4-piperidinone or 1-cyclohexyl-4-piperidinone.

3. The method of claim 1, wherein, The catalyst described in step (1) includes a combination of at least two of methanesulfonic acid, trifluoropropionic acid, pentafluoropropionic acid, dichloromethane, trifluoromethanesulfonic acid, pentafluoroacetic acid, or trifluoroacetic acid.

4. The method of claim 1, wherein, The catalyst described in step (1) comprises a combination of pentafluoropropionic acid and trifluoromethanesulfonic acid.

5. The method of claim 3, wherein, The volume of the pentafluoropropionic acid is 5 mL.

6. The method of claim 3, wherein, The volume of the trifluoromethanesulfonic acid is 50 mL.

7. The method of claim 1, wherein, In step (1), the first solvent includes any one or a combination of at least two of toluene, chloromethane, chloroform or tetrachloroethane.

8. The method of claim 1, wherein, The temperature of the first reaction in step (1) is 2℃ and the time is 10h.

9. The method of claim 1, wherein, The second solvent in step (1) includes any one or a combination of at least two of dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone.

10. The method of claim 1, wherein, The temperature of the secondary reaction in step (1) is 70°C and the time is 12h.

11. The method according to claim 1, characterized in that, The third solvent mentioned in step (2) includes dimethyl sulfoxide and / or deionized water.

12. The method of claim 1, wherein, The fixing device includes any one of a tension fixing device, an adsorption fixing device, or a clamp fixing device.

13. The method of claim 1, wherein, The coating method includes scraping.

14. The method of claim 1, wherein, The drying method includes any one of heating drying, microwave drying, or ultraviolet drying.

15. The method of claim 14, wherein, The heating and drying temperature is 60~100℃.

16. A hydrogen-oxygen type composite polymer alkaline anion exchange membrane, characterized by, The hydrogen-oxygen composite polymer basic anion exchange membrane is prepared by the method for preparing hydrogen-oxygen composite polymer basic anion exchange membrane according to any one of claims 1-15.

17. An electrolyte membrane, characterized by, The electrolyte membrane includes the hydroxyl-oxygen composite polymer alkaline anion exchange membrane according to claim 16.

18. An electrolytic cell characterized by, The electrolytic cell includes the electrolyte membrane according to claim 17.

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