High-proton-conductivity and high-durability proton exchange membrane and preparation method thereof

Abstract

The invention provides a proton exchange membrane with high proton conductivity and high durability and a preparation method thereof. The preparation method comprises the following steps: (a) mixing or / and reacting sulfonated polymer dispersion liquid and perfluorinated sulfonic acid resin dispersion liquid to obtain sulfonated polymer modified perfluorinated sulfonic acid resin membrane solution or membrane dispersion liquid; the mass ratio of the sulfonated polymer in the sulfonated polymer dispersion liquid to the perfluorinated sulfonic acid resin in the perfluorinated sulfonic acid resin dispersion liquid is (0.5-50): (50-99.5); and (b) directly forming a film from the sulfonated polymer modified perfluorosulfonic acid resin film solution or the film dispersion liquid, or coating the sulfonated polymer modified perfluorosulfonic acid resin film solution or the film dispersion liquid and a skeleton enhanced film to form the film. On the premise of ensuring high conductivity, the temperature resistance of the membrane is improved, the hydrogen permeability and swelling ratio are reduced, and the generation of free radicals is reduced, so that the durability of the membrane is indirectly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to a proton exchange membrane, in particular to a proton exchange membrane with high proton conductivity and high durability and a preparation method thereof. Background Art

[0002] Perfluorosulfonic acid proton exchange membrane (i.e. perfluorosulfonic acid resin proton exchange membrane) is a perfluoropolymer material developed as the main key material of proton exchange membrane battery. Its raw material is perfluorosulfonic acid resin (PFSA). PFSA is a perfluoropolymer with a polytetrafluoroethylene structure as the skeleton and a sulfonate ether structure side chain at the end. It is usually obtained by hydrolysis and conversion of perfluorosulfonyl fluoride resin (PFSR). Perfluorosulfonyl resin is obtained by copolymerization of tetrafluoroethylene (TFE) and perfluoroalkyl vinyl ether containing sulfonyl group (the representative compound is perfluoro(4-methyl-3.6-dioxa-7-octene)sulfonyl fluoride, PSVE); among them, tetrafluoroethylene provides a fluorocarbon skeleton for the polymer, which makes the perfluorosulfonyl resin have extremely strong chemical stability; perfluoroalkyl vinyl ether provides sulfonic acid groups, thereby ensuring the electrochemical performance of the proton exchange membrane.

[0003] Perfluorosulfonic acid proton exchange membrane is commonly used as a diaphragm in fuel cells, electrolyzers and flow batteries. When used in fuel cells, it can transfer hydrogen ions while blocking the transfer of electrons, hydrogen and oxygen, thereby establishing an effective unidirectional positively charged proton transmission channel between the anode and cathode of the battery. As the most commonly used proton exchange membrane, perfluorosulfonic acid proton exchange membrane has excellent chemical stability, thermal stability and mechanical properties, and can adapt to extreme environments such as high temperature, high pressure and high humidity.

[0004] However, perfluorosulfonic acid proton exchange membranes have the following disadvantages: (1) Currently commercialized proton exchange membranes have hydrogen leakage from the anode side to the cathode side and oxygen leakage from the cathode side to the anode side, i.e., cross leakage. When cross leakage occurs, a so-called chemical short circuit occurs, making it impossible to obtain a good voltage, causing the proton exchange membrane to chemically deteriorate, which in turn further aggravates the permeability, resulting in a significant decrease in the main indicators of the proton exchange membrane, such as mechanical strength, proton conductivity, and high-temperature durability, and ultimately leading to a significant decrease in the durability of the membrane. This problem is more significant when the proton exchange membrane is relatively thin; (2) The hydrogen on the anode side and the oxygen on the cathode side may react with each other to produce hydrogen peroxide, resulting in a decrease in the durability of the proton exchange membrane; (3) The temperature resistance and strength of the current perfluorosulfonic acid resin proton exchange membrane need to be further improved to meet the current market demand for thinner, more durable, and low-cost proton exchange membranes. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a method for preparing a proton exchange membrane with high proton conductivity and high durability, by using a high-performance sulfonated polymer to modify the perfluorosulfonic acid resin by combining physical mixing and chemical cross-linking network, or introducing reducing groups, so that the obtained proton exchange membrane has good proton conductivity and at the same time has extremely low hydrogen permeability and strong peroxide reduction performance, significantly improves strength and achieves excellent durability.

[0006] In order to achieve the above technical objectives, the present invention provides a method for preparing a proton exchange membrane with high proton conductivity and high durability, comprising the following steps: (a) mixing or / and reacting a sulfonated polymer dispersion with a perfluorosulfonic acid resin dispersion to obtain a sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion; the mass ratio of the sulfonated polymer in the sulfonated polymer dispersion to the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 0.5-50:50-99.5; the sulfonated polymer is obtained by sulfonating one or more of the following polymers to be sulfonated and then mixing them in proportion: polyamide, polyimide, polyethyleneimine, polyphenylene sulfide, poly(p-phenylene benzobisoxazole), polyethersulfone, polyphenylsulfone, polyetherketone, polyetheretherketone, polyetherketoneketone, polyarylate, liquid crystal polymer, poly(p-phenylene terephthalamide), polybenzimidazole, poly(2,5-dihydroxy-1,4-phenylenepyridiniumbiimidazole) and polyphenylquinoxaline; (b) directly forming a membrane from the sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion, or coating the sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion with a skeleton-reinforced membrane to form a membrane.

[0007] Optimally, in step (a), the EW value (i.e., ionic group equivalent value) of the perfluorosulfonic acid resin is 300~2000g / mol, and the solid content of the perfluorosulfonic acid resin dispersion is 1~50wt%; the EW value of the sulfonated polymer is 300~3000g / mol, and the solid content of the sulfonated polymer dispersion is 1~50wt%; the EW value of the sulfonated polymer modified perfluorosulfonic acid resin in the sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion is 700~3000g / mol.

[0008] Furthermore, in step (a), the perfluorosulfonic acid resin dispersion is prepared according to the following steps: the perfluorosulfonic acid resin, organic solvent and ultrapure water are dispersed at high temperature in a reactor, distilled and concentrated to adjust the solvent ratio, and filtered after the perfluorosulfonic acid resin particle size reaches the requirement.

[0009] Furthermore, in step (a), the sulfonated polymer is prepared by adding a sulfonating agent or a sulfonating agent solution to a dispersion of the polymer to be sulfonated to carry out a sulfonation reaction, filtering and drying the residue.

[0010] Furthermore, the sulfonating agent is a mixture of one or more selected from fuming sulfuric acid, concentrated sulfuric acid and chlorosulfonic acid, and the ratio of the content of -SO3- in the sulfonating agent to the mass of the polymer to be sulfonated is 0.1~50mmol / g.

[0011] Furthermore, the sulfonation reaction is carried out at a temperature of 10-140° C., a time of 1-10 h, and a stirring speed of 100-1000 rpm.

[0012] Optimally, in step (a), the sulfonated polymer is obtained by sulfonating the first polymer to be sulfonated, or by sulfonating the first polymer to be sulfonated and the second polymer to be sulfonated respectively and then mixing them in a mass ratio of 0.5~5:...:n (0~5); The first polymer to be sulfonated is polyamide, polyimide, polyethyleneimine, polyphenylene sulfide, poly(p-phenylene benzobisoxazole), polyethersulfone, polyphenylsulfone, polyetherketone, polyetheretherketone, polyetherketoneketone, polyarylate, liquid crystal polymer, poly(p-phenylene terephthalamide), polybenzimidazole, poly(2,5-dihydroxy-1,4-phenylenepyridiniumbiimidazole) or polyphenylquinoxaline, The second polymer to be sulfonated is selected from a plurality of polymers including polyamide, polyimide, polyethyleneimine, polyphenylene sulfide, poly(p-phenylene benzobisoxazole), polyethersulfone, polyphenylsulfone, polyetherketone, polyetheretherketone, polyetherketoneketone, polyarylate, liquid crystal polymer, poly(p-phenylene terephthalamide), polybenzimidazole, poly(2,5-dihydroxy-1,4-phenylene pyridine diimidazole) and polyphenylquinoxaline, and the type of each polymer to be sulfonated in the second polymer to be sulfonated is different from the type of the first polymer to be sulfonated; n is the number of types of each polymer to be sulfonated in the second polymer to be sulfonated.

[0013] Optimally, in step (b), the sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion is cast on a substrate to form a homogeneous membrane and then formed at a high temperature; or the ePTFE microporous membrane is used as a skeleton reinforced membrane for multiple cast coatings to form a membrane; or the woven membrane woven by PEEK polymer fibers is used as a skeleton reinforced membrane for multiple cast coatings to form a membrane and then formed at a high temperature; the temperature of the cast coating is 30°C~150°C, and the time is 10min~120min, and the temperature of the molding is 150°C~250°C, and the time is 3min~30min.

[0014] Another object of the present invention is to provide a proton exchange membrane with high proton conductivity and high durability, which is prepared by the above preparation method.

[0015] Optimally, its thickness is 5-100 μm.

[0016] The method for preparing a proton exchange membrane with high proton conductivity and high durability of the present invention comprises the following steps: mixing or reacting a specific sulfonated polymer with a perfluorosulfonic acid resin dispersion in a certain proportion and then coating and drying the mixture to form a membrane, so that the sulfonated polymer is uniformly dispersed in the membrane to form a chemical or physical three-dimensional cross-linked network structure, or a reducing group is introduced. Under the premise of ensuring high conductivity, the temperature resistance of the membrane is improved, the hydrogen permeability and swelling rate are reduced, the generation of free radicals is reduced, and the durability of the membrane is indirectly improved, thereby improving the mechanical strength and stability of the membrane and enhancing the stability of the membrane. In addition, the sulfonated polymer promotes the conduction of protons in the membrane, and ensures the high proton conduction performance of the membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the application of the high proton conductivity and high durability proton exchange membrane of the present invention (application one); Figure 2 This is a schematic diagram of the application of the high proton conductivity and high durability proton exchange membrane of the present invention (application 2); Figure 3 This is a schematic diagram of the application of the high proton conductivity and high durability proton exchange membrane of the present invention (application three). DETAILED DESCRIPTION

[0018] The preparation method of the high proton conductivity and high durability proton exchange membrane of the present invention comprises the following steps: (a) mixing or / and reacting a sulfonated polymer dispersion with a perfluorosulfonic acid resin dispersion to obtain a sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion; the mass ratio of the sulfonated polymer in the sulfonated polymer dispersion to the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 0.5~50:50~99.5, and the reaction conditions are preferably: the temperature is room temperature~180°C; NaOH can be added as needed during or after the reaction, so that the mass ratio of NaOH to the sulfonated polymer is 2~30:100, and finally exchanged into a hydrogen ion type proton exchange membrane solution. The sulfonated polymer is the following polymer to be sulfonated (commercially available, the weight average molecular weight can be selected from 1×10 3 ~2×10 6The method comprises the following steps of: (a) sulfonating one or more of the following polymers to be sulfonated, as long as they can be dissolved or dispersed and undergo sulfonation reaction, or first sulfonating one or more of the following polymers to be sulfonated separately and then mixing them in proportion to obtain the obtained polymers: polyamide (PA), polyimide (PI), polyethyleneimine (PEI), polyphenylene sulfide (PPS), poly(p-phenylene benzobisoxazole) (PBO), polyethersulfone (PES), polyphenylsulfone (PPSU), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyarylate (PAR), liquid crystal polymer (LCP), poly(p-phenylene terephthalamide) (PPTA), polybenzimidazole (PBI), poly(2,5-dihydroxy-1,4-phenylene pyridodiimidazole) (PIPD) and polyphenylquinoxaline (PPQ); (b) directly forming a membrane solution or a membrane dispersion, or coating the membrane solution or the membrane dispersion with a skeleton-reinforced membrane to form a membrane. By using a specific sulfonated polymer and a perfluorosulfonic acid resin dispersion to mix or react in proportion and then coating and drying to form a film, the sulfonated polymer is uniformly dispersed in the membrane to form a chemical or physical three-dimensional cross-linked network structure, or reducing groups are introduced. Under the premise of ensuring high conductivity, the temperature resistance of the membrane is improved, the hydrogen permeability and swelling rate are reduced, and the introduction of reducing groups reduces the free radical concentration in the membrane, thereby improving the mechanical strength and durability of the membrane and enhancing the stability of the membrane; in addition, the sulfonated polymer promotes the conduction of protons in the membrane, ensuring the high proton conductivity of the membrane.

[0019] The general chemical structure of the perfluorosulfonic acid resin is shown in formula (1): (1); In the formula, x is 0-4, y is 1-6, m is 1-15, and n is 200-1000; preferably, x is 0-3, y is 1-5, m is 1-13, and n is 220-950; more preferably, x is 0-2, y is 1-3, m is 1-10, and n is 250-900; the selection of x, y, m and n ensures that the comprehensive performance of the proton exchange membrane, such as conductivity and strength, is optimal.

[0020] In step (a), the mass ratio of the sulfonated polymer to the perfluorosulfonic acid resin is preferably 1.5-40:60-98.5, more preferably 2-35:65-98, and optimally 2-30:70-98, so as to further improve the physical and chemical properties of the proton exchange membrane (the mass ratio of the sulfonated polymer to the perfluorosulfonic acid resin can be any numerical ratio within the aforementioned range, such as 0.5:99.5, 1.5:98.5, 5:95, 10:90, 20:80, 30:70, 50:50, etc.). The EW value of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 300-2000 g / mol, preferably 500-1000 g / mol, more preferably 550-900 g / mol, and most preferably 600-850 g / mol; the EW value of the sulfonated polymer in the sulfonated polymer dispersion is 300-3000 g / mol, preferably 350-2500 g / mol, and more preferably 450-2000 g / mol. The EW value of the sulfonated polymer modified perfluorosulfonic acid resin in the sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion is 700-3000 g / mol, preferably 750-2950 g / mol, and more preferably 800-2900 g / mol. By controlling the raw material ion exchange equivalent, it is beneficial to further adjust the hydrophilicity of the final proton exchange membrane, promote the conduction of protons in the membrane, and further improve the proton conduction performance. The perfluorosulfonic acid resin dispersion is a process for dispersing perfluorosulfonic acid resin, organic solvent (organic solvents include but are not limited to methanol, ethanol, n-propanol, isopropanol glycol, propylene glycol, glycerol, butanediol, butanetriol, hexanediol, N-methylformamide (NMF), N-methylformamide (DMSO), N-methylpyrrolidone (NMP), dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc), which can be a single solvent or a mixture of multiple solvents) and ultrapure water (can also be a mixture of water and alcohol) in a reactor (usually a high-pressure reactor) at high temperature, distilling and concentrating to adjust the solvent ratio, and filtering and taking the filtrate after the particle size of the perfluorosulfonic acid resin reaches the requirement. The process conditions for high-temperature dispersion are: temperature 150-280°C, time 3-48h; preferably: temperature 150~260°C, time 4-24h; more preferably: temperature 150~200°C, time 5-12h. The average particle size of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion after dispersion is in the range of 1-500nm, preferably 5-300nm, and more preferably 10-250nm. The solid content of the perfluorosulfonic acid resin dispersion at the initial stage of dispersion is 1-10wt%, preferably 1.5-8wt%, and more preferably 2-6wt%; the solid content after concentration and filtration is 1-50wt%, preferably 10-45wt%, and more preferably 15-40wt% (unless otherwise specified, the solid content of the perfluorosulfonic acid resin dispersion generally refers to the solid content after concentration and filtration).In addition, the solvent can be replaced according to the needs (such as the possibility of incompatibility of the solvent used when mixing with the sulfonated polymer) by utilizing the different boiling points of different solvents during the high-temperature dispersion or distillation concentration process (or directly on the perfluorosulfonic acid resin dispersion) (specifically: a certain volume of replacement solvent is divided into multiple parts, one part is first added to the perfluorosulfonic acid resin dispersion, and evaporated or volatilized at a certain temperature and pressure (the replacement solvent is usually much less volatile than the aforementioned organic solvent) for a period of time; this is repeated multiple times, and the replacement solvent will replace the organic solvent (it may replace all or most of it); the replacement solvent includes but is not limited to water, methanol, ethanol, n-propanol, isopropanol, ethylene glycol, propylene glycol, glycerol, butylene glycol, butanetriol, hexanediol, N-methylformamide (NMF), N-methylformamide (DMSO), N-methylpyrrolidone (NMP), dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc), which can be a single solvent or a mixed solvent of multiple solvents.

[0021] In step (a), the sulfonated polymer is prepared according to the following steps: add a sulfonating agent or a sulfonating agent solution to the polymer dispersion to be sulfonated (refer to the dispersion method of the aforementioned perfluorosulfonic acid resin, the dispersion solvent may include but is not limited to methanol, ethanol, n-propanol, isopropanol ethylene glycol, propylene glycol, glycerol, butanediol, butanetriol, hexanediol, N-methylformamide (NMF), N-methylformamide (DMSO), N-methylpyrrolidone (NMP), dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc), which may be a single solvent or a mixture of multiple groups of solvents) to carry out a sulfonation reaction, and filter and dry the precipitate. The sulfonating agent is a mixture of one or more selected from fuming sulfuric acid, concentrated sulfuric acid and chlorosulfonic acid, and the ratio of the equivalent of -SO3- (i.e., the molar amount of SO3 group) in the sulfonating agent to the mass of the polymer is 0.1~50mmol / g, preferably 0.2~45mmol / g, and more preferably 0.5~40mmol / g. The sulfonation reaction is carried out at a temperature of 10-140°C, a time of 1-10 hours, and a stirring speed of 100-1000 rpm, preferably at a temperature of 20-100°C, a time of 2-8 hours, and a stirring speed of 200-900 rpm, more preferably at a temperature of 23-60°C, a time of 3-6 hours, and a stirring speed of 300-800 rpm. After the reaction is completed, the residue is filtered (and may also be washed with water and acid washed), dried, and crushed with a turbine disc mill to a particle size of 10 μm-1500 μm, preferably 20 μm-1200 μm, and more preferably 25 μm-1000 μm.

[0022] The sulfonated polymer dispersion is prepared by dispersing the sulfonated polymer in an organic solvent. The dispersion method and solid content are basically the same as those of the aforementioned perfluorosulfonic acid resin, except for the dispersion temperature and dispersion time. A small amount of sodium hydroxide needs to be added. In step (a), the sulfonated polymer is obtained by sulfonating the first polymer to be sulfonated, or by sulfonating the first polymer to be sulfonated and the second polymer to be sulfonated respectively, and then mixing them at a mass ratio of 0.5 to 5:…:n (0~5) are mixed to obtain; the first polymer to be sulfonated is a high-performance polymer such as polyamide (PA), polyimide (PI), polyethyleneimine (PEI), polyphenylene sulfide (PPS), poly(p-phenylene benzobisoxazole) (PBO), polyethersulfone (PES), polyphenylene sulfone (PPSU), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyarylate (PAR), liquid crystal polymer (LCP), poly(p-phenylene terephthalamide) (PPTA), polybenzimidazole (PBI), poly(2,5-dihydroxy-1,4-phenylene pyridodiimidazole) (PIPD) and polyphenylquinoxaline (PPQ); the second polymer to be sulfonated is selected from polyamide ( The invention relates to a plurality of high-performance polymers such as poly(PA), polyimide (PI), polyethyleneimine (PEI), polyphenylene sulfide (PPS), poly(p-phenylene benzobisoxazole) (PBO), polyethersulfone (PES), polyphenylsulfone (PPSU), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyarylate (PAR), liquid crystal polymer (LCP), poly(p-phenylene terephthalamide) (PPTA), polybenzimidazole (PBI), poly(2,5-dihydroxy-1,4-phenylene pyridinium diimidazole) (PIPD) and polyphenylquinoxaline (PPQ), wherein the types of the second polymers to be sulfonated are different from the types of the first polymers to be sulfonated. n is the number of types of each polymer to be sulfonated in the second polymer to be sulfonated. For example, when n is 2, the second polymer to be sulfonated is composed of two different components (also different from the first polymer to be sulfonated). After they are sulfonated separately, they are mixed in a mass ratio of 0.5~5 (first polymer to be sulfonated): (0~5): (0~5) to obtain the desired sulfonated polymer (the lower limit of the ratio is not 0 at this time).

[0023] Referring to the preparation method of the aforementioned perfluorosulfonic acid resin dispersion, the sulfonated polymer and the following solvents are dispersed in a reactor at high temperature. The types of solvents used include, but are not limited to, ultrapure water, ethanol, n-propanol, ethylene glycol, propylene glycol, glycerol, butanediol, butanetriol, hexanediol, N-methylformamide (NMF), N-methylformamide (DMSO), N-methylpyrrolidone (NMP), dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc), which can be a single solvent or a mixture of multiple groups of the above solvents. The high-temperature dispersion is carried out under nitrogen protection at a temperature of 80~230°C and a time of 1-12 hours.

[0024] In step (b), the sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion is cast on a substrate (such as a conventional mold or a commercially available PI membrane, etc.) to form a homogeneous membrane and molded at high temperature; or the ePTFE microporous membrane is used as a skeleton reinforced membrane for multiple cast coatings to form a membrane; or the braided membrane woven by PEEK polymer fibers is used as a skeleton reinforced membrane for multiple cast coatings to form a membrane and molded at high temperature. The temperature of the cast coating is 30°C~150°C and the time is 10~120min, preferably the temperature is 35°C~145°C and the time is 15~115min, more preferably the temperature is 40°C~140°C and the time is 20~100min. The temperature of the high temperature molding is 150°C~250°C and the time is 3~30min, preferably the temperature is 155°C~245°C and the time is 4-28min, more preferably the temperature is 160°C~240°C and the time is 5~25min.

[0025] The high proton conductivity and high durability proton exchange membrane prepared by the above method has a thickness of 5-100 μm, a planar proton conductivity (temperature and humidity: 80 ° C, 95% RH) of about 0.050-0.175 s / cm, and a hydrogen permeability of about 4×10 -4 ~0.027cm 3 / (m 2 ·24h·Pa), swelling rate (XY) is about 9.8-12.5%, MD tensile strength is about 29.5~51.1MPa, accelerated chemical durability test is about ≤3.9×10 -8 gF·cm -2 ·h -1 , accelerated mechanical durability can reach up to 4000 hours, and it has excellent physical and chemical properties and application performance.

[0026] The present invention also provides an application of a proton exchange membrane with high proton conductivity and high durability, wherein a membrane solution (i.e., a sulfonated polymer modified perfluorosulfonic acid resin membrane solution or a membrane dispersion, the same below) is coated on both surfaces of an ePTFE microporous membrane 2' and solidified (the membrane solution is solidified to form a proton exchange membrane layer 1') into a membrane unit used as a diaphragm for a fuel cell, such as Figure 1As shown. At this time, the thickness of the diaphragm is preferably 5~13μm. The coating temperature is 30℃~130℃, and the time is 10~115min, preferably the temperature is 35℃~110℃, and the time is 15~110min, and the temperature is more preferably 40℃~100℃, and the time is 20~100min; the curing temperature is 130℃~250℃, and the time is 3min-30min, preferably the temperature is 150℃~240℃, and the time is 4~28min, and the temperature is more preferably 160℃~230℃, and the time is 5~25min. The present invention also provides an application of a high proton conductivity and high durability proton exchange membrane, which is directly cured on a mold or a PI membrane to form a diaphragm 1'' used as a liquid flow battery, such as Figure 2 As shown. The coating temperature is 30℃~150℃, the time is 10~120min, preferably the temperature is 35℃~145℃, the time is 15~115min, more preferably the temperature is 40℃~140℃, the time is 20~100min; the curing temperature is 135℃~250℃, the time is 3~30min, preferably the temperature is 150℃~245℃, the time is 4~28min, more preferably the temperature is 160℃~230℃, the time is 5~25min. At this time, the thickness of the separator is preferably 25~80μm.

[0027] The present invention also provides an application of a proton exchange membrane with high proton conductivity and high durability, wherein a membrane solution is coated or injected between a braided membrane or two PEEK braided membranes 2, and then the membrane solution is coated on the outer surface of the braided membrane or two PEEK microporous membranes 2 to solidify (the membrane solution solidifies to form a proton exchange membrane layer 1) and the membrane unit is used as a diaphragm of an electrolytic cell (such as Figure 3 As shown). The coating temperature is 30°C~130°C, the time is 10~115min, preferably the temperature is 35°C~110°C, the time is 15~110min, more preferably the temperature is 40°C~100°C, the time is 20~100min; the curing temperature is 135°C~245°C, the time is 3~30min, preferably the temperature is 150°C~240°C, the time is 4~28min, more preferably the temperature is 160°C~230°C, the time is 5~25min. At this time, the thickness of the separator is preferably 50~100μm.

[0028] The preferred embodiments of the present invention will be described in detail below. Example 1

[0029] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which are specifically as follows: (a) 5 g of perfluorosulfonic acid resin (Solvay D79-25BS) was dispersed in 95 g of ethanol aqueous solution (containing 76 g of water and 19 g of ethanol), and distilled and concentrated to obtain a perfluorosulfonic acid resin dispersion with a solid content of 10 wt%; specifically, 5 g of perfluorosulfonic acid resin and 95 g of ethanol aqueous solution were dispersed at high temperature (170°C, 8 h) in a high temperature and high pressure reactor; the high temperature dispersion was cooled to room temperature and then distilled and concentrated (70-75°C) to basically remove ethanol, and the filtrate was filtered to obtain a 10 wt% perfluorosulfonic acid resin dispersion (at this time, the particle size range of the perfluorosulfonic acid resin in the dispersion was approximately 100-250 nm, and the EW value was about 790 g / mol).

[0030] 1g polyphenylene sulfide (Suwei R-4-230BL), 1g poly(p-phenylene benzobisoxazole) (Shanghai Ruiyan Aramid) and 2g chlorosulfonic acid were dissolved in 20ml chloroform (i.e., three portions of 20ml chloroform) to obtain their respective solutions; the chlorosulfonic acid solution was evenly divided into two portions, and slowly added to the polyphenylene sulfide solution and the poly(p-phenylene benzobisoxazole) solution at 25°C, respectively. After the addition was completed, the mixture was stirred at a speed of 500-800rpm for 3-4h (the reaction temperature was controlled at 50-60°C, refluxed for sufficient reaction, and products precipitated during the reaction). After the reaction was completed, the precipitates were filtered out respectively, and the precipitates were combined, washed and dried to obtain a sulfonated polymer (about 2.2g, EW value was about 1500g / mol).

[0031] The obtained sulfonated polymer (2 g) was added to 10 g of ethanol, followed by 0.04 g of NaOH, and the mixture was placed in a high-temperature and high-pressure reactor and dispersed at 190° C. and a corresponding high pressure for 12 hours to obtain a sulfonated polymer dispersion with a solid content of 16.6%.

[0032] 0.6 g of the above-mentioned sulfonated polymer dispersion (containing about 0.1 g of sulfonated polymer) was added to 50 g of perfluorosulfonic acid resin dispersion (containing about 5 g of perfluorosulfonic acid resin), and the mixture was mixed at 60° C. for 12 hours. The membrane-forming solution (EW value was about 950 g / mol) was obtained after the mixture was evenly mixed. Then, a cation exchange resin (success 232) was used to exchange the pH value of the solution to 1-2 (the sodium ion concentration was less than 0.1 ppm. In this embodiment, each parameter range had no effect on the performance of the product).

[0033] (b) The membrane-forming solution (after ion exchange) was subjected to solution casting coating (temperature: 80°C, time: 30 min), and then subjected to high-temperature molding (temperature: 160°C, time: 10 min) to obtain a proton exchange membrane (thickness: about 50 μm, measured to be 51.9 mm). Example 2

[0034] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 1, except that: in step (a), 0.6 g of sulfonated polymer dispersion (containing about 0.1 g of sulfonated polymer) is added to 4 g of perfluorosulfonic acid resin dispersion (containing about 0.4 g of perfluorosulfonic acid resin), mixed at 60°C for 12 hours, and mixed evenly to obtain a membrane-forming solution. Example 3

[0035] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 1, except that: in step (a), 0.6 g of sulfonated polymer dispersion (containing about 0.1 g of sulfonated polymer) is added to 1.9 g of perfluorosulfonic acid resin dispersion (containing about 0.19 g of perfluorosulfonic acid resin), and the mixture is mixed at room temperature for 12 hours to obtain a membrane-forming solution. Example 4

[0036] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 1, except that: in step (a), 0.6 g of sulfonated polymer dispersion (containing about 0.1 g of sulfonated polymer) is added to 1.5 g of perfluorosulfonic acid resin dispersion (containing about 0.15 g of perfluorosulfonic acid resin), and the mixture is mixed at room temperature for 12 hours to obtain a membrane-forming solution. Example 5

[0037] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 1, except that: in step (a), 0.6 g of sulfonated polymer dispersion (containing about 0.1 g of sulfonated polymer) is added to 1.0 g of perfluorosulfonic acid resin dispersion (containing about 0.1 g of perfluorosulfonic acid resin), and the mixture is mixed at room temperature for 12 hours to obtain a membrane-forming solution. Example 6

[0038] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 1, except that: in step (a), 0.6 g of sulfonated polymer dispersion (containing about 0.1 g of sulfonated polymer) is added to 66 g of perfluorosulfonic acid resin dispersion (containing about 6.6 g of perfluorosulfonic acid resin), mixed at room temperature for 12 hours, and mixed evenly to obtain a membrane-forming solution. Example 7

[0039] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that: in step (a), 2 g of polyamide (PA66) is used for sulfonation. Example 8

[0040] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that: in step (a), 2 g of polyimide (100HN) is used for sulfonation. Example 9

[0041] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that in step (a), 2 g of polyethyleneimine (SP-018) is used for sulfonation. Example 10

[0042] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that in step (a), 2 g of polyethersulfone (E6010) is used for sulfonation. Embodiment 11

[0043] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that in step (a), 2 g of polyetherketone (RTP 2287 A) is used for sulfonation. Example 12

[0044] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that: in step (a), 2 g of polyetheretherketone (PEEK-CA30) is used for sulfonation. Example 13

[0045] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that in step (a), 2 g of poly (p-phenylene terephthalamide) (DuPont injection molding 4001) is used for sulfonation. Embodiment 14

[0046] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that in step (a), 2 g of polybenzimidazole (Duratron CU60) is used for sulfonation. Embodiment 15

[0047] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that: in step (a), 2 g of poly (2,5-dihydroxy-1,4-phenylene pyridinium diimidazole (M5) is used for sulfonation. Example 16

[0048] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that in step (a), 2 g of polyphenylquinoxaline (PPQ) is used for sulfonation. Embodiment 17

[0049] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that: in step (a), 1g of polyphenylene sulfide and 1g of polybenzimidazole (Duratron CU60) are used. Embodiment 18

[0050] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that in step (a), 1 g polyphenylene sulfide, 0.5 g poly(p-phenylene benzobisoxazole) and 0.5 g polybenzimidazole (Duratron CU60) are used. Embodiment 19

[0051] This embodiment provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 2, except that: in step (a), 0.5 g of polyphenylene sulfide, 0.5 g of poly(p-phenylene benzobisoxazole), 0.5 g of polybenzimidazole (Duratron CU60) and 0.5 g of polyimide (100HN) are used.

[0052] Comparative Example 1 This example provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 1, except that: in step (a), 0.6 g of sulfonated polymer dispersion (containing about 0.1 g of sulfonated polymer) is added to 0.67 g of perfluorosulfonic acid resin dispersion (containing about 0.067 g of perfluorosulfonic acid resin), mixed at room temperature for 12 hours, and mixed evenly to obtain a membrane-forming solution.

[0053] Comparative Example 2 This example provides a high proton conductivity and high durability proton exchange membrane and a preparation method thereof, which is basically the same as that in Example 1, except that: in step (a), no sulfonated polymer dispersion is added, and only 50g of perfluorosulfonic acid resin dispersion (containing about 5g of perfluorosulfonic acid resin) is used.

[0054] Application Example 1 This example is basically the same as that in Example 1, except that in step (b), the membrane-forming solution (after ion exchange) is solution-casted (temperature: 80°C, time: 30 min) to be coated on both surfaces of the 3 μm PTFE microporous membrane, and then high-temperature molding (temperature: 160°C, time: 10 min) is performed to obtain a proton exchange membrane (thickness: 8 μm).

[0055] Application Example 2 This example is basically the same as that in Example 1, except that in step (b), the thickness of the proton exchange membrane is 80 μm.

[0056] Application Example 3 This example is basically the same as that in Example 1, except that in step (b), the membrane-forming solution (after ion exchange) is solution-casted (temperature: 80°C, time: 30 min) to be coated on both surfaces of a 43 μm PEEK braided membrane, and a proton exchange membrane (thickness: 80 μm) is formed at high temperature (temperature: 160°C, time: 10 min).

[0057] The proton exchange membranes in Examples 1-19 and Comparative Examples 1-2 were tested, and the results are listed in Table 1.

[0058] Table 1 Performance of the proton exchange membranes in Examples 1-19 and Comparative Examples 1-2

[0059] Table 1 continued:

[0060] Note: The test conditions for proton conductivity (i.e. planar proton conductivity) are: temperature 80°C, humidity 95%RH, and the test method is the high-frequency resistance method (i.e. measuring the proton resistance, the proton exchange membrane impedance when the imaginary part of the impedance is zero; the test standard refers to GB / T2004.3-2022).

[0061] The hydrogen permeability is measured by cyclic voltammetry (CV), and the test standard refers to GB / T 2004.3-2022.

[0062] Both MD tensile strength and TD tensile strength are measured in accordance with the standard reference GB / T 2004.3-2022.

[0063] The test temperature of swelling rate (XY) is 80℃ and the test standard refers to GB / T 2004.3-2022.

[0064] Mechanical durability test method: test the proton conductivity, hydrogen permeability, tensile strength and EW value of the sample at room temperature; then fix the sample on the experimental rack; the temperature, humidity, time and other conditions are: 80℃, pure water immersion for 1h; pull out of the water and air-dry at 80℃ for 30 minutes; immerse in water again to enter the next cycle; do it continuously for 3000 hours, and then monitor the tensile strength every 100 hours. If the performance decline is greater than 20% of the initial performance, the test is stopped, and the corresponding time is the accelerated durability time.

[0065] Test method for chemical durability test: Put the sample into a container, add Fenton reagent, soak it at 80℃ for 2h, then take it out and measure the fluoride ion concentration in Fenton reagent (*Fenton reagent: 3% hydrogen peroxide, 4ppm divalent iron ion). ND means no detection.

[0066] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a proton exchange membrane with high proton conductivity and high durability, characterized in that: The following steps are involved: (a) mixing or / and reacting a sulfonated polymer dispersion with a perfluorosulfonic acid resin dispersion to obtain a sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion; the mass ratio of the sulfonated polymer in the sulfonated polymer dispersion to the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 0.5-50:50-99.5; the sulfonated polymer is obtained by sulfonating one or more of the following polymers to be sulfonated and then mixing them in proportion: polyamide, polyimide, polyethyleneimine, polyphenylene sulfide, poly(p-phenylene benzobisoxazole), polyethersulfone, polyphenylsulfone, polyetherketone, polyetheretherketone, polyetherketoneketone, polyarylate, liquid crystal polymer, poly(p-phenylene terephthalamide), polybenzimidazole, poly(2,5-dihydroxy-1,4-phenylenepyridiniumbiimidazole) and polyphenylquinoxaline; (b) directly forming a membrane from the sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion, or coating the sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion with a skeleton-reinforced membrane to form a membrane.

2. The method for preparing a proton exchange membrane with high proton conductivity and high durability according to claim 1, characterized in that: In step (a), the EW value of the perfluorosulfonic acid resin is 300-2000 g / mol, and the solid content of the perfluorosulfonic acid resin dispersion is 1-50 wt %; the EW value of the sulfonated polymer is 300-3000 g / mol, and the solid content of the sulfonated polymer dispersion is 1-50 wt %; the EW value of the sulfonated polymer modified perfluorosulfonic acid resin in the sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion is 700-3000 g / mol.

3. The method for preparing a proton exchange membrane with high proton conductivity and high durability according to claim 2, characterized in that: In step (a), the perfluorosulfonic acid resin dispersion is prepared by the following steps: dispersing the perfluorosulfonic acid resin, an organic solvent and ultrapure water in a reactor at high temperature, distilling and concentrating to adjust the solvent ratio, and filtering after the perfluorosulfonic acid resin particle size reaches the required size.

4. The method for preparing a proton exchange membrane with high proton conductivity and high durability according to claim 2, characterized in that: In step (a), the sulfonated polymer is prepared by adding a sulfonating agent or a sulfonating agent solution to a dispersion of the polymer to be sulfonated to carry out a sulfonation reaction, filtering and drying the residue.

5. The method for preparing a proton exchange membrane with high proton conductivity and high durability according to claim 4, characterized in that: The sulfonating agent is a mixture of one or more selected from fuming sulfuric acid, concentrated sulfuric acid and chlorosulfonic acid, and the ratio of the content of -SO3- in the sulfonating agent to the mass of the polymer to be sulfonated is 0.1-50 mmol / g.

6. The method for preparing a proton exchange membrane with high proton conductivity and high durability according to claim 4, characterized in that: The temperature of the sulfonation reaction is 10-140° C., the time is 1-10 hours, and the stirring speed is 100-1000 rpm.

7. The method for preparing a proton exchange membrane with high proton conductivity and high durability according to claim 1, characterized in that: In step (a), the sulfonated polymer is obtained by sulfonating the first polymer to be sulfonated, or by sulfonating the first polymer to be sulfonated and the second polymer to be sulfonated respectively and then mixing them in a mass ratio of 0.5-5:...:n (0-5); The first polymer to be sulfonated is polyamide, polyimide, polyethyleneimine, polyphenylene sulfide, poly(p-phenylene benzobisoxazole), polyethersulfone, polyphenylsulfone, polyetherketone, polyetheretherketone, polyetherketoneketone, polyarylate, liquid crystal polymer, poly(p-phenylene terephthalamide), polybenzimidazole, poly(2,5-dihydroxy-1,4-phenylenepyridiniumbiimidazole) or polyphenylquinoxaline, The second polymer to be sulfonated is selected from a plurality of polymers including polyamide, polyimide, polyethyleneimine, polyphenylene sulfide, poly(p-phenylene benzobisoxazole), polyethersulfone, polyphenylsulfone, polyetherketone, polyetheretherketone, polyetherketoneketone, polyarylate, liquid crystal polymer, poly(p-phenylene terephthalamide), polybenzimidazole, poly(2,5-dihydroxy-1,4-phenylene pyridine diimidazole) and polyphenylquinoxaline, and the type of each polymer to be sulfonated in the second polymer to be sulfonated is different from the type of the first polymer to be sulfonated; n is the number of types of each polymer to be sulfonated in the second polymer to be sulfonated.

8. The method for preparing a proton exchange membrane with high proton conductivity and high durability according to claim 1, characterized in that: In step (b), the sulfonated polymer modified perfluorosulfonic acid resin membrane solution or membrane dispersion is cast on a substrate to form a homogeneous membrane and then formed at a high temperature; or the ePTFE microporous membrane is used as a skeleton reinforced membrane for multiple cast coatings to form a membrane; or the woven membrane woven by PEEK polymer fibers is used as a skeleton reinforced membrane for multiple cast coatings to form a membrane and then formed at a high temperature; the casting coating temperature is 30°C to 150°C, the time is 10min to 120min, and the molding temperature is 150°C to 250°C, and the time is 3min to 30min.

9. A high proton conductivity and high durability proton exchange membrane, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 8.

10. The high proton conductivity and high durability proton exchange membrane according to claim 9, characterized in that: Its thickness is 5~100μm.

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