Composite ion exchange membrane, method for preparing the same, and use thereof

Abstract

The application belongs to the field of high polymer materials and functional materials, and particularly relates to a composite ion exchange membrane, a preparation method and application thereof. The composite ion exchange membrane disclosed by the embodiment of the application comprises 90-99.99% of ion exchange resin and 0.01-10% of cerium-based coordination polymer, in terms of mass percentage. The organic ligand in the cerium-based coordination polymer in the composite ion exchange membrane has better compatibility when it is blended with the ion exchange membrane, so that the composite ion exchange membrane has better chemical stability.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and functional materials, and specifically relates to a composite ion exchange membrane and its preparation method. Background Technology

[0002] Ion exchange membranes are widely used in fuel cell proton exchange membranes, chlor-alkali industry membranes, flow battery membranes, water electrolysis hydrogen production proton exchange membranes, separation membranes, and protective materials. In fuel cells, the degradation of other components such as catalysts and gas diffusion layers generally only leads to a decrease in cell performance. However, damage to the ion exchange membrane can directly cause mixing of reacting gases at the anode and cathode, resulting in direct cell failure or even safety accidents. Therefore, the development of high-performance, high-durability proton exchange membranes is crucial for the development of fuel cells.

[0003] During fuel cell operation, the proton exchange membrane (PEM) is susceptible to attack by hydroxyl radicals, which can lead to performance degradation, perforation, and even fuel cell failure. Therefore, improving its chemical durability to overcome the performance degradation and shortened lifespan caused by hydroxyl radical attack is urgently needed. Summary of the Invention

[0004] This invention is based on the inventor's discoveries and understanding of the following facts and problems:

[0005] Doping cerium ions, cerium-based metal salts, or cerium-based metal oxides into ion exchange resins allows cerium to act as a free radical quencher, thereby improving the chemical stability of the proton exchange membrane. Current techniques involve impregnating ion exchange membranes with cerium ion solutions or doping them with cerium-based metal salts / metal oxides to prepare fuel cell proton exchange membranes with high chemical durability. While impregnation with cerium ions is simple, it leads to a significant decrease in the proton transport capacity of the proton exchange membrane, sacrificing electrochemical performance. Unmodified cerium-based metal salts / metal oxides have poor compatibility with polymers, uneven dispersion in the membrane material, and limited doping amounts, all of which restrict the application of cerium-doped ion exchange membranes.

[0006] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a composite ion exchange membrane in which the organic ligands in the cerium-based coordination polymer improve its compatibility with the ion exchange membrane when blended, thereby giving the composite ion exchange membrane better chemical stability.

[0007] The composite ion exchange membrane of this invention comprises 90-99.99% ion exchange resin and 0.01-10% cerium-based coordination polymer, by mass percentage.

[0008] The advantages and technical effects of the composite ion exchange membrane in this invention are as follows: 1. In this invention, a cerium-based coordination polymer and an ion exchange resin are used to prepare the composite ion exchange membrane. The presence of organic ligands in the coordination polymer can overcome the problem of uneven dispersion of cerium-based metal salts and metal oxides in the ion exchange resin, giving cerium elements good dispersion in the ion exchange resin. It can also avoid the problem of cerium ions directly contacting the sulfonic acid functional groups in the ion exchange resin to form counterionic crosslinks, which would reduce conductivity. 2. In this invention, the cerium ions at the coordination center of the cerium-based coordination polymer can act as hydroxyl radical quenchers, significantly improving the chemical durability of the composite ion exchange membrane. 3. In this invention, the ion exchange membrane can be used in polyelectrolyte membranes, proton exchange membranes for water electrolysis to produce hydrogen, acidic primary battery membranes, secondary battery membranes such as lithium batteries, polyelectrolytes in supercapacitors, polyelectrolyte membranes for metal recycling batteries, sensors, and other fields, and has broad application prospects.

[0009] In some embodiments, the metal ion at the coordination center of the cerium-based coordination polymer includes Ce. 3+ and Ce 4+ At least one of them.

[0010] In some embodiments, the cerium-based coordination polymer includes at least one of a one-dimensional coordination polymer, a two-dimensional coordination network, and a three-dimensional coordination network.

[0011] The organic ligands of the cerium-based coordination polymer include at least one of sulfonic acid organic ligands and carboxylic acid organic ligands; preferably, the organic ligands include disodium ethylenediaminetetraacetate, N-(4-benzoic acid)iminodiacetic acid, (5-ethoxycarbonyl-6-phenyl-1,6-dihydropyrimidin-2-one-4-yl)methanesulfonic acid, R-2-(4-(4-carboxybenzyloxy)phenoxy)propionic acid, (5-ethoxycarbonyl) At least one of the following: 6-bromophenyl-1,6-dihydropyrimidin-2-one-4-yl)methanesulfonic acid, 1,1'-ferrocene dicarboxylic acid, (5-ethoxycarbonyl-6-methyl-1,6-dihydropyrimidin-2-one-4-yl)methanesulfonic acid, 1,10-phenanthroline-2,9-dicarboxylic acid, (5-ethoxycarbonyl-6-hydro-1,6-dihydropyrimidin-2-one-4-yl)methanesulfonic acid, 5-aminoisophthalic acid, and neopentanoic acid.

[0012] In some embodiments, the unit cell volumes of the one-dimensional coordination polymer, the two-dimensional coordination network, and the three-dimensional coordination network are: Preferred More preferably

[0013] In some embodiments, the cerium-based coordination polymer comprises at least one of a two-dimensional porous MOF and a three-dimensional porous MOF;

[0014] Among them, the particle size of two-dimensional porous MOFs or three-dimensional porous MOFs is 5-800 nm, and the BET specific surface area is 40-3000 m². 2 / g, micropore volume is 0.01~1.5cm³ 3 / g;

[0015] Preferably, the organic ligands of the cerium-based coordination polymer include sulfonic acid organic ligands;

[0016] More preferably, it includes at least one of dicarboxylic acid organic ligands, tricarboxylic acid organic ligands, tetracarboxylic acid organic ligands, and sulfonic acid functionalized organic ligands;

[0017] More preferably, the binary, ternary, or tetracarboxylic acid organic ligands include 2,2'-thiodicarboxylic acid, 1,3,5-tribenzoylbenzene, 2,2'-dithiodicarboxylic acid, 3,6-benzobutanedicarboxylic acid, 1,4-phthalic acid, 4,4'4"-triphenylamine tricarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine, 4,4'-biphenyldicarboxylic acid, phenyl-1,2,4,5-tetracarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, 4,5,9,10-tetrahydropyrene-2,7-dicarboxylic acid, [1,1'-biphenyl]-3, At least one of 3',5,5'-tetracarboxylic acid, pyrene-2,7-dicarboxylic acid, 4',5'-bis(4-carboxyphenyl)-[1,1':2',1”-terphenyl]-4,4”-dicarboxylic acid, [1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid, 1,3,6,8-tetracarboxylic acid pyrene, 1,3,5-benzenetricarboxylic acid, 4,4',4”,4”'-methanetetrabenzoic acid, [1,1'-biphenyl]-3,4',5-tricarboxylic acid and 5',5”-bis(4-carboxyphenyl)-[1,1':3',1”:3”,1”-tetraphenyl]-4,4”-dicarboxylic acid;

[0018] More preferably, the sulfonic acid-functionalized dicarboxylic acid organic ligand includes at least one of 2-sulfonic terephthalic acid, 3,7-disulfonaphthal-2,6-dicarboxylic acid, 5-sulfonaphthalic acid, 4,8-disulfonaphthal-2,6-dicarboxylic acid, 2,5-disulfonaphthalic acid, 3,3'-disulfonyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid, 5,7-disulfonaphthal-1,4-dicarboxylic acid, 4-sulfonaphthalic acid-4'4"-dicarboxylic acid triphenylamine, 6-sulfonaphthal-1,4-dicarboxylic acid, and [1,1'-biphenyl]-4'-sulfonaphthalic acid-3,5-dicarboxylic acid.

[0019] In some embodiments, the ion exchange resin includes at least one of perfluorosulfonic acid resin, perfluorosulfonyl imide resin, polyacid side-chain perfluoro resin, sulfonated polytrifluorostyrene, sulfonated polysulfone, sulfonated polyethersulfone, sulfonated polyether ether ketone, sulfonated polyarylene ether ketone, sulfonated polyarylene ether nitrile, sulfonated polyphosphazene, sulfonated polyphenylene ether, sulfonated polyphenylene nitrile, sulfonated polyimide, and sulfonated polybenzimidazole; preferably, it includes at least one of perfluorosulfonic acid resin, perfluorosulfonyl imide resin, polyacid side-chain perfluoro resin, sulfonated polytrifluorostyrene, sulfonated polyether ether ketone, sulfonated polyarylene ether ketone, and sulfonated polyarylene ether nitrile; more preferably, it includes at least one of perfluorosulfonic acid resin, perfluorosulfonyl imide resin, polyacid side-chain perfluoro resin, and sulfonated polytrifluorostyrene.

[0020] In some embodiments, the composite ion exchange membrane has a thickness of 3–500 μm and an ion exchange capacity of 0.1–4.2 mmol / g.

[0021] This invention also provides a method for preparing a composite ion exchange membrane, comprising the following steps:

[0022] (1) Disperse the ion exchange resin and cerium-based coordination polymer in a solvent to obtain a dispersion;

[0023] (2) The dispersion obtained in step (1) is cast, poured or coated and then dried to obtain a composite ion exchange membrane.

[0024] The advantages and technical effects of the composite ion exchange membrane preparation method of this invention are as follows: 1. In this invention, the composite ion exchange membrane prepared by this method has good flatness, uniform thickness distribution, and better performance; 2. The method of this invention is simple and easy to operate, and has high production efficiency, making it easy to be widely used in industrial production; 3. The dispersion liquid mentioned in the preparation process of this invention can also be used to prepare coatings, hydrogels, and adhesives for porous membranes such as desalination membranes (nanofiltration membranes) and ultra / microfiltration membranes, as well as various fabrics in the biomedical field such as surgical gloves, medical protective clothing, and sterile drapes, and protective equipment for biological and chemical battlefields such as military protective clothing, thus having a wide range of applications.

[0025] In some embodiments, step (2) further includes loading the dispersion obtained in step (1) onto a reinforcing membrane and drying it to obtain a composite ion exchange membrane; preferably, the reinforcing membrane is a porous membrane.

[0026] In some embodiments, the mass content of the reinforcing membrane is 0.1% to 90% of the composite ion exchange membrane, and the thickness of the reinforcing membrane is 2 to 400 μm.

[0027] In some embodiments, the reinforcing membrane material includes at least one of non-fluorinated polyolefins, fluoropolymers, and aromatic polymers; preferably, the non-fluorinated polyolefin includes at least one of polyethylene, polypropylene, and ethylene-propylene copolymers; the fluoropolymer includes at least one of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymers, tetrafluoroethylene-propylene copolymers, ethylene-tetrafluoroethylene copolymers, tetrafluoroethylene-hexafluoropropylene-ethylene copolymers, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymers, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymers, polyvinyl fluoride, polychlorotrifluoroethylene, and ethylene-chlorotrifluoroethylene copolymers; the aromatic polymer membrane includes at least one of polyaryletherketone, polysulfone, polyethersulfone, polyethersulfoneketone, polybenzimidazole, polyarylamide, polyimide, and polyetheretherketone.

[0028] This invention also provides an application of composite ion exchange membranes in polyelectrolyte membranes in the chlor-alkali industry, proton exchange membranes for hydrogen production by water electrolysis, primary battery membranes for acidic batteries, secondary battery membranes such as lithium batteries, polyelectrolytes in supercapacitors, polyelectrolyte membranes for metal recycling batteries, or sensors. Attached Figure Description

[0029] Figure 1 This is a cross-sectional SEM image of C-PEM-3 obtained in Example 22 before Fenton reagent treatment;

[0030] Figure 2 This is a cross-sectional SEM image of C-PEM-3 obtained in Example 22 after treatment with Fenton's reagent;

[0031] Figure 3 This is a cross-sectional SEM image of DC-PEM-7 prepared in Comparative Example 8 before Fenton reagent treatment.

[0032] Figure 4 This is a cross-sectional SEM image of DC-PEM-7 prepared in Comparative Example 8 after treatment with Fenton's reagent.

[0033] Figure 5 These are the power density curves of C-PEM-3 prepared in Example 22 and DC-PEM-7 prepared in Comparative Example 8 before and after Fenton reagent treatment. Detailed Implementation

[0034] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0035] The composite ion exchange membrane of this invention comprises 90-99.99% ion exchange resin and 0.01-10% cerium-based coordination polymer, by mass percentage.

[0036] The composite ion exchange membrane of this invention uses a cerium-based coordination polymer and an ion exchange resin to prepare the composite ion exchange membrane. The presence of organic ligands in the coordination polymer can overcome the problem of uneven dispersion of cerium-based metal salts and metal oxides in the ion exchange resin, giving cerium elements good dispersion in the ion exchange resin. It can also avoid the problem of cerium ions directly contacting the sulfonic acid functional groups in the ion exchange resin and causing counterionic crosslinking, which would reduce conductivity. The cerium ions at the coordination center of the cerium-based coordination polymer can act as hydroxyl radical quenchers, significantly improving the chemical durability of the composite ion exchange membrane. The ion exchange membrane can be used in polyelectrolyte membranes, proton exchange membranes for water electrolysis to produce hydrogen, acidic primary battery membranes, secondary battery membranes such as lithium batteries, polyelectrolytes in supercapacitors, polyelectrolyte membranes for metal recycling batteries, sensors, and other fields, and has broad application prospects.

[0037] In some embodiments, preferably, the metal ion at the coordination center of the cerium-based coordination polymer includes Ce. 3+ and Ce 4+ At least one of them.

[0038] In some embodiments, preferably, the cerium-based coordination polymer includes at least one of a one-dimensional coordination polymer, a two-dimensional coordination network, and a three-dimensional coordination network.

[0039] The organic ligands of the cerium-based coordination polymer include at least one of sulfonic acid organic ligands and carboxylic acid organic ligands; preferably, the organic ligands include at least one of the following:

[0040]

[0041] In this embodiment of the invention, the preferred topology is a one-dimensional, two-dimensional, or three-dimensional structure. When the topology is one-dimensional, the resulting straight-chain one-dimensional cerium-based coordination polymer has a small size, a large specific surface area, and a higher quenching efficiency for hydroxyl radicals. Two-dimensional or three-dimensional structures can extend the transport path of gases and small organic molecules, improve the barrier properties of the material, and can also be used as inorganic fillers for polymer materials to enhance the mechanical strength of composite ion exchange membranes.

[0042] In some embodiments, preferably, the unit cell volume of the one-dimensional coordination polymer, the two-dimensional coordination network, and the three-dimensional coordination network is Preferred More preferably

[0043] In this embodiment of the invention, the cell volume of the coordination polymer is preferred, which is beneficial to its dispersion in the ion exchange resin, resulting in better performance of the composite ion exchange membrane.

[0044] In some embodiments, preferably, the dried and shaped coordination polymer is processed to a suitable size using physical methods such as grinding and / or ball milling. More preferably, the particle size of the processed coordination polymer material is 1 nm to 1000 nm, more preferably 2 nm to 600 nm, and more preferably 3 nm to 300 nm.

[0045] In some embodiments, preferably, the cerium-based coordination polymer comprises at least one of a two-dimensional porous MOF and a three-dimensional porous MOF;

[0046] Among them, the particle size of two-dimensional porous MOFs or three-dimensional porous MOFs is 5-800 nm, and the BET specific surface area is 40-3000 m². 2 / g, micropore volume is 0.01~1.5cm³ 3 / g; preferably, the particle size is 10-500 nm, and the BET specific surface area is 100-2500 m² / g. 2 / g, micropore volume is 0.02~1.2cm³ 3 / g; more preferably, the particle size is 30–300 nm, and the BET specific surface area is 120–2200 m². 2 / g, micropore volume is 0.02~0.9cm³ 3 / g;

[0047] Preferably, the organic ligands of the cerium-based coordination polymer include sulfonic acid organic ligands;

[0048] More preferably, it includes at least one of dicarboxylic acid organic ligands, tricarboxylic acid organic ligands, tetracarboxylic acid organic ligands, and sulfonic acid functionalized organic ligands;

[0049] More preferably, the binary, ternary, or tetracarboxylic acid organic ligand includes at least one of the following:

[0050]

[0051]

[0052]

[0053] More preferably, the sulfonic acid-functionalized dicarboxylic acid organic ligand comprises at least one of the following:

[0054]

[0055]

[0056] In this embodiment of the invention, the organic ligand of the coordination polymer is preferably a two-dimensional porous MOF or a three-dimensional porous MOF. When the topology is a two-dimensional porous MOF or a three-dimensional porous MOF, the cerium-based coordination polymer formed is beneficial to the conduction of protons and extends the transport path of gas and small organic molecules, thereby improving the conductivity and barrier properties of the composite ion exchange membrane and the mechanical strength of the composite ion exchange membrane.

[0057] In some embodiments, preferably, the ion exchange resin comprises at least one selected from perfluorosulfonic acid resin, perfluorosulfonyl imide resin, polyacid side-chain perfluororesin, sulfonated polytrifluorostyrene, sulfonated polysulfone, sulfonated polyethersulfone, sulfonated polyetheretherketone, sulfonated polyaryletherketone, sulfonated polyarylether nitrile, sulfonated polyphosphazene, sulfonated polyphenylene ether, sulfonated polyphenylene nitrile, sulfonated polyimide, and sulfonated polybenzimidazole; more preferably, it comprises at least one selected from perfluorosulfonic acid resin, perfluorosulfonyl imide resin, polyacid side-chain perfluororesin, sulfonated polytrifluorostyrene, sulfonated polyetheretherketone, sulfonated polyaryletherketone, and sulfonated polyarylether nitrile; more preferably, it comprises at least one selected from perfluorosulfonic acid resin, perfluorosulfonyl imide resin, polyacid side-chain perfluororesin, and sulfonated polytrifluorostyrene.

[0058] Preferably, the perfluorosulfonic acid resin is classified into acidic perfluorosulfonic acid resin, alkali metal type perfluorosulfonic acid resin, and other cationic perfluorosulfonic acid resin according to the different cations, wherein the general structural formula of the acidic perfluorosulfonic acid resin is:

[0059]

[0060] In the formula, m = 0 to 6, n = 2 to 5, x mainly determines the ion exchange equivalent (EW) of acidic perfluorosulfonic acid resin, and y mainly determines the molecular weight of acidic perfluorosulfonic acid resin;

[0061] The general structural formula of the alkali metal perfluorosulfonic acid resin is:

[0062]

[0063] In the formula, m = 0 to 6, n = 2 to 5, M is lithium, sodium, potassium, rubidium or cesium, x mainly determines the EW of alkali metal perfluorosulfonic acid resin, and y mainly determines the molecular weight of alkali metal perfluorosulfonic acid resin.

[0064] Preferably, the perfluorosulfonamide resin is classified into acidic perfluorosulfonamide resin, alkali metal perfluorosulfonamide resin, and other cationic perfluorosulfonamide resins according to the different cations. The general structural formulas of acidic and alkali metal perfluorosulfonamide resins are as follows:

[0065]

[0066] In the formula, m = 0 to 6, n = 2 to 5, p = 0 to 5, M' is hydrogen, lithium, sodium, potassium, rubidium, cesium or other cations, x' mainly determines the EW of the perfluorosulfonamide resin, and y' mainly determines the molecular weight of the perfluorosulfonamide resin.

[0067] Preferably, the polyacid side-chain perfluorinated resin is classified into acidic polyacid side-chain perfluorinated resin, alkali metal polyacid side-chain perfluorinated resin, and other cationic polyacid side-chain perfluorinated resin according to the different cations. The general structural formulas of acidic and alkali metal polyacid side-chain perfluorinated resins are as follows:

[0068]

[0069] In the formula, m = 0 to 6, n = 2 to 5, p = 0 to 5, M” is hydrogen, lithium, sodium, potassium, rubidium, cesium or other cations, x” mainly determines the EW of polyacid side-chain type perfluorinated resin, and y” mainly determines the molecular weight of polyacid side-chain type perfluorinated resin.

[0070] Preferably, the sulfonated polytrifluorostyrene has the following general structural formula:

[0071]

[0072] In the formula, M”' is hydrogen, lithium, sodium, potassium, rubidium, cesium or other cations, X1 is selected from H, F or CF3, and x”', y”' and z”' mainly determine the molecular weight and EW of sulfonated polytrifluorostyrene.

[0073] The cations include at least one of the following: ammonium ion, alkaline earth metal ion, iron ion, vanadium ion, titanium ion, cobalt ion, chromium ion, nickel ion, copper ion, aluminum ion, silver ion, zinc ion, manganese ion, and tin ion.

[0074] In some embodiments, preferably, the composite ion exchange membrane has a thickness of 3–500 μm and an ion exchange capacity of 0.1–4.2 mmol / g. More preferably, the composite ion exchange membrane has a thickness of 4–320 μm and an ion exchange capacity of 0.15–3.0 mmol / g. More preferably, the composite ion exchange membrane has a thickness of 5–200 μm and an ion exchange capacity of 0.2–2.5 mmol / g.

[0075] This invention also provides a method for preparing a composite ion exchange membrane, comprising the following steps:

[0076] (1) Disperse the ion exchange resin and cerium-based coordination polymer in a solvent to obtain a dispersion;

[0077] (2) The dispersion obtained in step (1) is cast, poured or coated and then dried to obtain a composite ion exchange membrane.

[0078] The method for preparing the composite ion exchange membrane according to the present invention produces a composite ion exchange membrane with good flatness, uniform thickness distribution, and better performance. The process is simple and easy to operate, with high production efficiency, making it suitable for widespread application in industrial production. The dispersion liquid mentioned in the preparation process can also be used to prepare coatings, hydrogels, and adhesives for porous membranes such as desalination membranes (nanofiltration membranes) and ultra / microfiltration membranes, as well as various fabrics in the biomedical field such as surgical gloves, medical protective clothing, and sterile drapes, and protective equipment for biological and chemical battlefields such as military protective clothing, demonstrating its wide range of applications.

[0079] In some embodiments, preferably, in step (1), the solvent includes at least one of water, a high-boiling-point organic solvent, tetrahydrofuran, and a lower fatty alcohol; the high-boiling-point organic solvent includes at least one of ethylene glycol, propylene glycol, glycerol, DMF, DMAc, DMSO, hexamethylphosphoric acid triamine, and NMP; and the lower fatty alcohol includes at least one of methanol, ethanol, isopropanol, and n-propanol.

[0080] In some embodiments, preferably, the dispersion temperature is 10–240°C, the pressure is atmospheric pressure to 20 MPa, and the dispersion time is 0.1–24 h; the dispersion method includes at least one of stirring, shaking, and ultrasonication.

[0081] In some embodiments, preferably, in step (2), the drying temperature is 20 to 180°C.

[0082] In some embodiments, preferably, step (2) further includes loading the dispersion obtained in step (1) onto a reinforcing membrane and drying it to obtain a composite ion exchange membrane; preferably, the reinforcing membrane is a porous membrane.

[0083] In some embodiments, preferably, the mass content of the reinforcing membrane is 0.1% to 90% of the composite ion exchange membrane, and the thickness of the reinforcing membrane is 2 to 400 μm. More preferably, the mass content of the reinforcing membrane is 1% to 70% of the composite ion exchange membrane, and the thickness of the reinforcing membrane is 2 to 300 μm. More preferably, the mass content of the reinforcing membrane is 3% to 50% of the composite ion exchange membrane, and the thickness of the reinforcing membrane is 2 to 180 μm.

[0084] In some embodiments, preferably, the material of the reinforcing membrane includes at least one of non-fluorinated polyolefins, fluoropolymers, and aromatic polymers; preferably, the non-fluorinated polyolefin includes at least one of polyethylene, polypropylene, and ethylene-propylene copolymers; the fluoropolymer includes at least one of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymers, tetrafluoroethylene-propylene copolymers, ethylene-tetrafluoroethylene copolymers, tetrafluoroethylene-hexafluoropropylene-ethylene copolymers, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymers, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymers, polyvinyl fluoride, polychlorotrifluoroethylene, and ethylene-chlorotrifluoroethylene copolymers; the aromatic polymer membrane includes at least one of polyaryletherketone, polysulfone, polyethersulfone, polyethersulfoneketone, polybenzimidazole, polyarylamide, polyimide, and polyetheretherketone.

[0085] This invention also provides an application of composite ion exchange membranes in polyelectrolyte membranes in the chlor-alkali industry, proton exchange membranes for hydrogen production by water electrolysis, primary battery membranes for acidic batteries, secondary battery membranes such as lithium batteries, polyelectrolytes in supercapacitors, polyelectrolyte membranes for metal recycling batteries, or sensors.

[0086] This invention also provides a method for preparing a cerium-based coordination polymer:

[0087] When the cerium-based coordination polymer is at least one of a one-dimensional coordination polymer, a two-dimensional coordination network, and a three-dimensional coordination network, its preparation method is as follows: dispersing cerium salt and organic ligand in a solvent, carrying out a hydrothermal reaction under acidic conditions, cooling to room temperature, filtering, washing, and drying to obtain the coordination polymer.

[0088] The cerium salt includes at least one of cerium nitrate, cerium chloride, cerium sulfate, and cerium acetate, and the organic ligand includes at least one of sulfonic acid organic ligands and carboxylic acid organic ligands.

[0089] The molar ratio of the cerium salt to the organic ligand is 1:0.5 to 4, preferably 1:1 to 3;

[0090] The solvent includes at least one selected from water, methanol, ethanol, acetonitrile, diethyl ether, dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP);

[0091] The acidity of the acidic conditions is 1 to 6, preferably 1 to 5; the solution for adjusting the acidity includes at least one of sulfuric acid solution, hydrochloric acid solution, trifluoroacetic acid solution, triethylamine, and sodium hydroxide solution.

[0092] The hydrothermal reaction temperature is 20–200°C, and the hydrothermal reaction time is 12–84 hours;

[0093] The solvent used for washing includes at least one of water, methanol, ethanol, acetonitrile, DMF, and DMAc.

[0094] When the cerium-based coordination polymer is at least one of a two-dimensional porous MOF and a three-dimensional porous MOF, it is prepared by hydrothermal synthesis, which includes at least one of the following synthesis methods:

[0095] Synthesis Method 1

[0096] (1) Dissolve the organic ligand in a high-boiling-point organic solvent to form an organic ligand solution, and simultaneously dissolve the cerium salt in a high-boiling-point organic solvent to form a cerium salt solution; wherein the molar ratio of the organic ligand to the cerium salt is 1:(2-5), and each 0.005 mmol of cerium salt corresponds to 0.5 mL to 3 mL of organic solvent, and the volume ratio of the solvent in the organic ligand solution and the cerium salt solution is 1:(2-10); after sonicating the organic ligand solution and the cerium salt solution at room temperature for 0.5 to 2 hours, the cerium salt solution is slowly added dropwise to the organic ligand solution;

[0097] (2) After the mixed solution is sonicated for 1 to 2 hours, ammonia or sodium hydroxide solution is added dropwise to adjust the pH to 4 to 5; the suspension is transferred to a hydrothermal reactor and sealed in a forced-air oven for 18 to 48 hours at a reaction temperature of 100 to 200°C.

[0098] (3) After the reaction is complete, the container is allowed to cool naturally to room temperature. It is then washed with a high-boiling-point organic solvent and ethanol and centrifuged. The resulting white or light yellow precipitate is transferred to a vacuum oven for drying at a temperature of 150-200°C, and finally a white or light yellow powder is obtained.

[0099] Synthesis Method 2

[0100] (11) Add the organic ligand to an ethanol-water solution, add ammonia or 1 mol / L sodium hydroxide solution to form an organic ligand solution, and simultaneously add the cerium salt to the ethanol-water solution to form a cerium salt solution; wherein the molar ratio of the organic ligand to the cerium salt is 1:(2-5), the volume ratio of water to ethanol in the ethanol-water solution is 1:(2-4), the volume ratio of ammonia or sodium hydroxide solution to the ethanol-water solution is 5:(6-10), each 0.1 mmol of cerium salt corresponds to 4-8 mL of ethanol-water solution, and the volume ratio of ethanol-water solution in the organic ligand solution and the cerium salt solution is (2-5):1;

[0101] (12) Heat the organic ligand solution and stir until it is completely dissolved. After sonicating the cerium salt solution at room temperature for 2 to 5 hours, slowly add it dropwise to the cooled organic ligand solution. Continue to stir the mixed solution at room temperature for 12 to 24 hours.

[0102] (13) After the reaction is complete, the sample is washed with ultrapure water and ethanol and centrifuged. The white or light yellow precipitate is transferred to a vacuum oven for drying at a temperature of 150-200°C. Finally, a white or light yellow powder is obtained.

[0103] Synthesis Method 3

[0104] (21) Add the organic ligand, cerium salt and formic acid to a high-boiling organic solvent at the same time, wherein the molar ratio of the organic ligand and cerium salt is 1:(2-5), and each 0.1 mmol of cerium salt corresponds to 4-8 mL of high-boiling organic solvent and 0.2-1 mL of formic acid. Sonicate the mixed solution at room temperature for 0.5-2 hours.

[0105] (22) Transfer the ultrasonically mixed solution to a hydrothermal reactor and seal it in a forced-air drying oven for 18 to 48 hours at a reaction temperature of 100 to 200°C.

[0106] (23) After the reaction is complete, the container is allowed to cool naturally to room temperature. It is then washed with a high-boiling-point organic solvent and ethanol and centrifuged. The resulting white or light yellow precipitate is transferred to a vacuum oven to dry at a temperature of 150-200°C, and finally a white or light yellow powder is obtained.

[0107] The high-boiling-point organic solvent includes at least one of DMF, DMAc, DMSO and NMP; the cerium salt includes at least one of cerium nitrate, cerium chloride, cerium sulfate and cerium acetate.

[0108] The technical solution of the present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0109] The cerium salts and organic ligands used in the embodiments of this invention are from chemical reagent suppliers such as Aladdin, Maclean's Reagent, Bid Pharmaceutical, and Leyan Reagent; the perfluorosulfonic acid resin is from Chemours, 3M, and Solvay; the polyacid side-chain perfluoro resin is from 3M; the porous polyethersulfone membrane is from Zhejiang Tailin Biotechnology; the perfluorosulfonamide resin and the porous polytetrafluoroethylene membrane (ePTFE) are self-made; and other solvents are common chemical reagents.

[0110] Perfluorosulfonyl imide resin is prepared by free radical copolymerization of perfluorosulfonyl imide vinyl ether monomer and tetrafluoroethylene monomer.

[0111] Specifically, perfluorosulfonamide vinyl ether monomer and tetrafluoroethylene monomer (TFE) undergo a continuous copolymerization reaction in a Na2HPO4 / NaH2PO4 buffer solution using (NH4)2S2O8 / NaHSO3 as an initiator. First, Na2HPO4·7H2O and NaH2PO4 are fully dissolved in degassed deionized water (with a suitable amount of surfactant added) to prepare solution 1. Then, perfluorosulfonamide vinyl ether monomer 1 is added to solution 1, and nitrogen is continuously purged to cool the solution to 8°C. The initiator is then added to prepare solution 2. The autoclave is evacuated and purged with nitrogen three times within 5 minutes before the initiator is added to solution 2. Solution 2 is added to a metering pump reservoir and degassed with helium for at least 20 minutes. Solution 2 is then drawn into a fully evacuated autoclave, and a suitable amount of degassed deionized water is added to make the solution volume half the volume of the reactor. When the reactor temperature reaches 10°C, TFE is added until the pressure reaches 150 psi and the continuous addition pump is started to maintain the pressure between 145 and 150 psi throughout the process by adding TFE. Finally, the filtrate is acidified with 70% hydrochloric acid to obtain the precipitated polymer. The polymer is washed with water until the water is neutral and dried under full vacuum at 50°C for more than 12 hours to obtain perfluorosulfonamide resin.

[0112] Porous polytetrafluoroethylene (PTFE) membranes are prepared by a common biaxial stretching method: (1) 75 parts of PTFE powder (Cholmos 605XTX) and 25 parts of additive oil (aviation kerosene) are mixed and stirred evenly, and then calendered, compacted, and extruded to prepare a calendered strip containing additive oil; (2) the calendered strip is dried to obtain a degreased membrane, which is first stretched in the MD direction and then stretched in the TD direction. After heat setting, a porous PTFE membrane is obtained. The stretching ratio in the MD direction is 7 times, and the stretching ratio in the TD direction is 22 times. Among them, the mechanical force direction is MD, and the transverse direction of the mechanical force direction is TD.

[0113] Example 1

[0114] 1,10-phenanthroline-2,9-dicarboxylic acid and (CeNO3)3·6H2O in a molar ratio of 1:1 were added to water, mixed thoroughly, and the pH was adjusted to 1 with sulfuric acid solution before being sealed in a hydrothermal reactor. The reactor was heated to 180℃ and reacted for 72 hours, then gradually cooled to room temperature to obtain brown rod-shaped crystals. These crystals were filtered, washed successively with distilled water and DMF, and dried to obtain a one-dimensional chain-structured cerium coordination polymer {[Ce2(PDA)2(SO4)(H2O)6](H2O)3}n with a highly thermally stable unit cell volume of […]. After ball milling, the particle size distribution of this coordination polymer material is 3 nm to 10 nm, and it is named CPs-1. PDA is deprotonated 1,10-phenanthroline-2,9-dicarboxylic acid, and its structure is as follows:

[0115]

[0116] Example 2

[0117] (CeNO3)3·6H2O and neopentanoic acid in a molar ratio of 1:3 were added to methanol solvent, followed by triethylamine. The mixture was stirred thoroughly to dissolve and then filtered. The filtrate was slowly evaporated at room temperature to form needle-like crystals, which were washed with methanol and dried to obtain a one-dimensional chain-like cerium coordination polymer [Ce(piv)3(MeOH)2]n with a unit cell volume of [missing value]. The grain size is 0.25 × 0.15 × 0.10 mm. 3 The coordination polymer powder, after grinding, has a particle size distribution of 50 nm to 300 nm and is named CPs-2. piv is deprotonated neopentanoic acid, and its structure is as follows:

[0118]

[0119] Example 3

[0120] 1,1'-ferrocene dicarboxylic acid and Ce(NO3)3·6H2O were placed in a beaker at a molar ratio of 1.5:1. 10 mL of deionized water was added and stirred thoroughly until homogeneous. An appropriate amount of sodium hydroxide solution was then added, and the mixture was transferred to the inner liner of a hydrothermal reactor. After sealing the reactor, it was placed in an oven and heated to 110℃ for crystallization for 12 days. The mixture was then slowly cooled to room temperature and washed alternately with water and ethanol to obtain the two-dimensional coordination polymer {[Ce2(fcd)3·H2O]·H2O}n, with a unit cell volume of [missing information]. After ball milling, a powder with a particle size distribution of 30 nm to 120 nm was obtained and named CPs-3. Its fcd is the divalent anion [Fe(C5H4COO)2] formed by the removal of two protons from 1,1'-ferrocene dicarboxylic acid. 2- .

[0121] Example 4

[0122] CeCl3·7H2O and [5-ethoxycarbonyl-6-(4-bromophenyl)-1,6-dihydropyrimidinone]methanesulfonic acid (HL1) in a molar ratio of 1:3 were placed in a beaker. A mixed solvent of water and ethanol was then added, and the mixture was stirred to dissolve. The solution was filtered into a separate beaker and allowed to stand at room temperature to evaporate, yielding colorless flaky crystals {[Ce(L1)2(H2O)6](L1)(C2H5OH)2·3H2O}n, with a unit cell volume of [missing information]. The grain size is 0.05 × 0.10 × 0.25 mm. 3 After ball milling, a powder with a particle size distribution of 50 nm to 150 nm was obtained and named CPs-4. This coordination polymer has a two-dimensional molecular structure.

[0123] Example 5

[0124] Tridentate aromatic carboxylic acid ligands N-(4-benzoyl)iminodiacetic acid (H2L2) and (CeNO3)3·6H2O in a molar ratio of 1:1 were added to a polytetrafluoroethylene reactor. A mixture of acetonitrile and water in a volume ratio of 1:1 was added, and the mixture was stirred at room temperature for 20 min. The pH of the system was adjusted to 2 with 1M HCl solution. The reaction mixture was sealed and placed in an electrically heated drying oven, heated to 120℃, and maintained at this temperature for 3 days. The temperature was then lowered to room temperature at a rate of 5℃ per hour to obtain colorless crystals {[Ce(H3L2)(H2O)]}n, with a unit cell volume of [missing value]. Powder with a particle size distribution of 50 nm to 100 nm was obtained and named CPs-5. Ce(III) and carboxylic acid are linked to form one-dimensional chains, and these one-dimensional chains are linked by the three carboxylic acid groups of the ligand to form a two-dimensional bilayer planar structure.

[0125] Example 6

[0126] 5-Amino-isophthalic acid (H2aip) and (CeNO3)3·6H2O with water in a molar ratio of 1:2 were placed in a hydrothermal tank and refluxed in an oven at 150°C for 3 days. After cooling and filtration, colorless blocky crystals were obtained. The two-dimensional cerium-based complex {[Ce(aip)(Haip)(H2O)2]·H2O}n had a cell volume of 0.90307(18) nm. 3 After ball milling, a powder with a particle size distribution of 10 nm to 100 nm was obtained, which was named CPs-6.

[0127] Example 7

[0128] Didentate carboxylic acid ligand R-2-(4-(4-carboxybenzyloxy)phenoxy)propionic acid (H2L3) and (CeNO3)3·6H2O in a molar ratio of 1:1 were added to a polytetrafluoroethylene reactor. A mixture of acetonitrile and water in a volume ratio of 1:1 was then added. The mixture was stirred at room temperature for 30 min. The pH of the system was adjusted to 2 using a 25% trifluoroacetic acid solution. The reaction mixture was sealed and placed in an electrically heated drying oven, heated to 120°C, and maintained at this temperature for 3 days. The temperature was then lowered to room temperature at a rate of 5°C per hour to obtain colorless, blocky {[Ce2(H2L3)3(H2O)3]·H2O·CH3CN}n with a cell volume of [missing information]. After grinding and ball milling, a powder with a wavelength of 30 nm to 120 nm was obtained and named CPs-7. This coordination polymer has a three-dimensional molecular structure.

[0129] Example 8

[0130] (CeNO3)3·6H2O, 2,2'-thiodicarboxylic acid (H2TDA), and KOH in a molar ratio of 1:1.5 were added to a polytetrafluoroethylene reactor. After being fully dissolved in deionized water, the reactor was sealed and placed in an electric heating drying oven. The temperature was raised to 120°C and maintained for 24 hours. The reactor was then allowed to cool naturally to room temperature. After washing three times with deionized water and drying, a two-dimensional porous MOF material was obtained. The nanosheets formed had a thickness of 80–150 nm and a lateral dimension of 2–4 μm. After ball milling, the resulting powder was named MOF-1.

[0131] Example 9

[0132] The three-dimensional porous MOF-2 was prepared using the above-mentioned hydrothermal synthesis method.

[0133] The organic ligand is 1,4-phthalic acid, the high-boiling organic solvent is DMF, the cerium salt is (CeNO3)3·6H2O, the molar ratio of organic ligand to cerium salt is 1:2.5, each 0.005 mmol of cerium salt corresponds to 3 mL of organic solvent, and the volume ratio of solvent in the organic ligand solution and the cerium salt solution is 1:5. After sonicating each solution at room temperature for 1 hour, the cerium salt solution is slowly added dropwise to the organic ligand solution.

[0134] After sonicating the mixed solution for another hour, sodium hydroxide solution was added dropwise to adjust the pH to 4-5. The suspension was then transferred to a hydrothermal reactor and sealed in a forced-air oven for 18 hours at a reaction temperature of 120°C.

[0135] After the reaction was completed, a white precipitate was obtained and dried in a vacuum oven for 24 hours at a drying temperature of 150°C, eventually yielding a white powder.

[0136] Example 10

[0137] The three-dimensional porous MOF-3 was prepared using the above-mentioned hydrothermal synthesis method 2.

[0138] The organic ligand is 4,5,9,10-tetrahydropyrene-2,7-dicarboxylic acid, the cerium salt is CeCl3·7H2O, the molar ratio of the organic ligand to the cerium salt is 1:5, the volume ratio of water to ethanol in the ethanol-water solution is 1:2, the volume ratio of ammonia to ethanol-water solution is 5:8, each 0.1 mmol of cerium salt corresponds to 8 mL of ethanol-water solution, and the volume ratio of ethanol-water solution in the organic ligand solution and the cerium salt solution is 2:1.

[0139] The organic ligand solution was heated and stirred until completely dissolved. The cerium salt solution was sonicated at room temperature for 5 hours and then slowly added dropwise to the cooled organic ligand solution. The mixed solution was then stirred at room temperature for 24 hours.

[0140] After the reaction was completed, the sample was washed with ultrapure water and ethanol and then centrifuged to obtain a light yellow precipitate. The precipitate was then transferred to a vacuum oven for drying at 200°C, eventually yielding a light yellow powder.

[0141] Example 11

[0142] The three-dimensional porous MOF-4 was prepared using the above-mentioned hydrothermal synthesis method 3.

[0143] The organic ligand is 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine, and the cerium salt is cerium(III) acetate hydrate. The organic ligand, cerium salt, and formic acid are added to DMAc simultaneously, with a molar ratio of 1:2 between the organic ligand and the cerium salt. Each 0.1 mmol of cerium salt corresponds to 4 mL of DMAc and 1 mL of formic acid. The mixed solution is sonicated at room temperature for 2 hours.

[0144] The ultrasonically treated mixture was transferred to a hydrothermal reactor and sealed in a forced-air oven for 48 hours at a temperature of 200°C.

[0145] After the reaction was completed, the sample was washed with DMF and ethanol and then centrifuged to obtain a light yellow precipitate. The precipitate was then transferred to a vacuum oven and dried for 24 hours at a temperature of 150–200°C to obtain a light yellow powder.

[0146] Example 12

[0147] Unlike Example 11, the organic ligand was 5',5”-bis(4-carboxyphenyl)-[1,1':3',1”:3”,1”-tetraphenyl]-4,4”-dicarboxylic acid, and the molar ratio of the organic ligand to the cerium salt was 1:3. All other conditions were the same, and a white powder MOF-5 was finally obtained. MOF-5 has a three-dimensional porous structure.

[0148] Example 13

[0149] Unlike Example 9, the organic ligand used was 2-sulfonic acid terephthalic acid. The reaction was carried out in a sealed oven for 48 hours at a temperature of 200°C, with all other conditions remaining the same, ultimately yielding a light yellow powder, MOF-6. MOF-6 has a three-dimensional porous structure.

[0150] Example 14

[0151] Unlike Example 10, the organic ligand was 3,3'-disulfonyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid, and the cerium salt was cerium(IV) sulfate tetrahydrate. All other conditions were the same, resulting in a light yellow powder, MOF-7. MOF-7 has a three-dimensional porous structure.

[0152] Example 15

[0153] Unlike Example 12, the organic ligand used was 4,8-disulfonnaphthalene-2,6-dicarboxylic acid, while other conditions remained the same, ultimately yielding a light yellow powder, MOF-8. MOF-8 has a three-dimensional porous structure.

[0154] Example 16

[0155] Weigh 40 mg of each coordination polymer from Examples 1-7 (diluted in 0.5 mL of isopropanol) and add them to 200 g of D520 resin dispersion (Cholmous, perfluorosulfonic acid resin content 5%, EW 980 g / mol, solvent a mixture of water, ethanol and n-propanol). Stir and mix at room temperature for 24 hours, then coat the mixture onto a release membrane using a doctor blade. Dry at 80 °C for 1 hour, and heat-treat at 150 °C for 15 min to obtain an ion exchange membrane with a thickness of 50 ± 3 μm. The chemical structure of the perfluorosulfonic acid resin in the D520 resin dispersion is as follows:

[0156]

[0157] Example 17

[0158] 1 g of 3M 800 resin (3M Corporation, EW 800 g / mol) was weighed and dissolved in 4 mL of DMSO at 80 °C with stirring. Then, 0.1 mg, 1 mg, 5 mg, 10 mg, and 20 mg of the coordination polymer CPs-1 from Example 1 (CPs-1 diluted in 1 mL of DMSO) were added, and the mixture was ultrasonically dispersed for 10 min to obtain dispersions. The dispersions were cast into ultraflat petri dishes and dried at 180 °C for 6 hours to obtain ion exchange membranes with a thickness of 50 ± 4 μm.

[0159] The chemical structure of 3M 800 resin is as follows:

[0160]

[0161] Example 18

[0162] Weigh 90 mg of each MOF from Examples 8-15 and add them to 50 g of D72 resin dispersion (Solvay, perfluorosulfonic acid resin content 40%, EW 720 g / mol, solvent: water). Stir and mix at room temperature for 24 hours, then coat the mixture onto a release membrane using a doctor blade. Dry at 80°C for 1 hour and heat-treat at 150°C for 15 minutes to obtain an ion exchange membrane with a thickness of 50 ± 3 μm. The chemical structure of the perfluorosulfonic acid resin in the D72 resin dispersion is as follows:

[0163]

[0164] Example 19

[0165] 10g of the 3M800 resin from Example 17 was weighed and dissolved in 40g of a water-ethanol mixture (water to ethanol mass ratio of 2:3) at room temperature. 360mg of the coordination polymer CPs-1 from Example 1 was added, and the mixture was ultrasonically dispersed for 10min to obtain a dispersion. This dispersion was then coated onto a release membrane using a doctor blade, dried at 100°C for 15min, and heat-treated at 150°C for 5min. By controlling the doctor blade gap, ion exchange membranes of different thicknesses, PEM-21 and PEM-22, were obtained.

[0166] Example 20

[0167] Unlike Example 19, a release membrane was used as a substrate, and the membrane was coated onto both sides of an ePTFE membrane using a doctor blade. The composite ion exchange membrane C-PEM-1 was then prepared using the same heat treatment method. The ePTFE membrane had a thickness of 3±0.5 μm, a porosity of 75%, and a pore size distribution of 200–300 nm.

[0168] Example 21

[0169] Nine g of the 3M800 resin from Example 17 was weighed and dissolved in 40 g of DMF at room temperature. One g of the coordination polymer MOF-8 from Example 15 was added, and the mixture was ultrasonically dispersed for 10 min to obtain a dispersion. Using a release membrane as a substrate, the dispersion was applied to both sides of a porous polyethersulfone membrane via slit coating. The membrane was dried at 100°C for 1 hour and then heat-treated at 160°C for 15 min to obtain the composite ion exchange membrane C-PEM-2. The porous polyethersulfone membrane had a thickness of 120–140 μm and an average pore size of 0.45 μm.

[0170] Example 22

[0171] 10g of solid ion exchange resin was weighed and dissolved and dispersed in a water-alcohol mixture (water, ethanol, n-propanol, isopropanol, and n-butanol in a mass ratio of 2:1:1:1:1) at 60°C to obtain a resin dispersion. 50mg of MOF-8 from Example 18 was added to the resin dispersion, and the mixture was ultrasonically dispersed for 15min. The dispersion was then slit-coated onto both sides of an ePTFE membrane, dried at 90°C for 3min, and heat-treated at 180°C for 10min to obtain ion exchange membranes with thicknesses of 15±2μm, namely composite ion exchange membranes C-PEM-3, C-PEM-4, C-PEM-5, and C-PEM-6. The ePTFE membrane thickness was 7±1.5μm, the porosity was 72%, and the pore size distribution was between 180 and 270nm.

[0172] Among them, the solid ion exchange resin is 3M800, BAM3G, perfluorosulfonamide resin or PFIA;

[0173] 3M800 is the same as that in Example 17;

[0174] BAM3G is a sulfonated polytrifluorostyrene resin from Ballard, with an EW value of 407 g / mol and the following structural formula:

[0175]

[0176] In the formula, X1 is either F or CF3, and the ratio of the two substituents is uncertain;

[0177] Perfluorosulfonamide resin is obtained by copolymerizing tetrafluoroethylene with sulfonamide monomers, with an EW value of 1200 g / mol and the following structural formula:

[0178]

[0179] PFIA is a polyacid side-chain type perfluorinated resin from 3M, with an EW value of 625 g / mol and the following structural formula:

[0180]

[0181] Comparative Example 1

[0182] Unlike Example 16, no coordination polymer was added to the dispersion to obtain an ion exchange membrane D-PEM-1 with a thickness of 50±3μm.

[0183] Comparative Example 2

[0184] Unlike Example 17, no CPs-1 was added to the dispersion, and an ion exchange membrane D-PEM-2 with a thickness of 50±4μm was prepared.

[0185] Comparative Example 3

[0186] Unlike Example 18, no MOF was added to the dispersion, and an ion exchange membrane D-PEM-3 with a thickness of 50±3μm was prepared.

[0187] Comparative Example 4

[0188] Unlike Example 19, CPs-1 was not added to the dispersion, and ion exchange membranes D-PEM-4 and D-PEM-5 with different thicknesses were prepared.

[0189] Comparative Example 5

[0190] Unlike Example 20, no CPs-1 was added to the dispersion to obtain the composite ion exchange membrane DC-PEM-1.

[0191] Comparative Example 6

[0192] Unlike Example 21, MOF-8 was not added to the dispersion to obtain the composite ion exchange membrane DC-PEM-2.

[0193] Comparative Example 7

[0194] Unlike Example 22, the ion exchange resin was 3M800, and 50 mg of nano-cerium oxide (CeO2) was added to the dispersion instead of MOF-8 to prepare the composite ion exchange membrane DC-PEM-3.

[0195] Comparative Example 8

[0196] Unlike Example 22, MOF-8 was not added to the dispersion, and composite ion exchange membranes DC-PEM-4, DC-PEM-5, DC-PEM-6 and DC-PEM-7 were prepared using ion exchange resin BAM3G, perfluorosulfonamide resin, PFIA and 3M800, respectively.

[0197] Test case

[0198] Cell volume of coordination polymers: determined by single-crystal X-ray diffraction.

[0199] MOF particle size distribution: observed using SEM.

[0200] The BET specific surface area of ​​MOF was determined using an ASIQ-MI001-5 physical adsorption instrument from CANTA Corporation, USA.

[0201] Micropore volume of MOF: calculated using the t-plot method.

[0202] The test methods for conductivity, EW, IEC, tensile strength, tensile strain at break and water absorption rate are in accordance with GB / T20042.3-2022 "Proton Exchange Membrane Fuel Cells Part 3: Test Methods for Proton Exchange Membranes"; the test conditions for conductivity are a temperature of 80℃ and a relative humidity of 95%.

[0203] Fuel cell polarization curve: The test method refers to GB / T20042.5-2022 "Proton exchange membrane fuel cells Part 5: Membrane electrode test method".

[0204] Free radical resistance of ion exchange membranes: Immersing ion exchange membranes in Fenton's reagent at 80℃ for 8 hours, the mass loss and conductivity decay before and after immersion were compared. Preparation of Fenton's reagent: 0.1 mL of 0.01 mol / L Fe2+ solution was added dropwise to 50 mL of 3% (w / w) H2O2 solution. 2+ The solution, i.e., the prepared Fenton reagent, should be prepared fresh for immediate use. The smaller the percentage of mass loss of the ion exchange membrane after Fenton reagent treatment, the better its durability; the smaller the decrease in conductivity, the better its resistance to free radicals.

[0205] (1) Table 1 shows the particle size distribution and cell volume of the coordination polymers prepared in Examples 1 to 7.

[0206] Table 1

[0207]

[0208] (2) Table 2 shows the particle size, BET specific surface area and micropore volume of the MOF materials prepared in Examples 8 to 15.

[0209] Table 2

[0210] Example 8 MOF-1 30～60 127 0.06 Example 9 MOF-2 50～100 670 0.34 Example 10 MOF-3 30～70 1250 0.59 Example 11 MOF-4 50～80 1430 0.79 Example 12 MOF-5 30～40 2160 0.88 Example 13 MOF-6 30～50 1120 0.62 Example 14 MOF-7 200～300 1580 0.79 Example 15 MOF-8 30～40 1650 0.80

[0211] (3) The composite ion exchange membranes prepared in Example 16 and Comparative Example 1 were treated with Fenton's reagent. The mass loss after treatment is shown in Table 3.

[0212] Table 3

[0213]

[0214] As can be seen from the data in Table 3, compared with Comparative Example 1, the free radical durability of the composite ion exchange membrane is significantly improved after doping with cerium-based coordination polymer, and the mass loss of the composite ion exchange membrane is significantly reduced; the better free radical durability enables it to have better safety and reliability in long-term operation.

[0215] (4) The IEC, water absorption rate and mass loss of the composite ion exchange membranes with different CPs-1 addition amounts prepared in Example 17 and Comparative Example 2 were tested. The results are shown in Table 4.

[0216] Table 4

[0217]

[0218]

[0219] As can be seen from the data in Table 4, compared with Comparative Example 2, the changes in IEC and water absorption rate of the composite ion exchange membrane are smaller after doping with a small amount of cerium-based coordination polymer, and the free radical durability is improved; even the ion exchange membrane PEM-8 with a CPs-1 mass content of about 0.01% shows a significant reduction in mass loss compared with D-PEM-2.

[0220] (5) The composite ion exchange membranes prepared in Example 18 and Comparative Example 3 were treated with Fenton's reagent. The mass loss after treatment is shown in Table 5.

[0221] Table 5

[0222]

[0223] As can be seen from the data in Table 5, compared with Comparative Example 3, the mass loss of the composite ion exchange membrane after treatment with Fenton's reagent was significantly reduced after doping with cerium-based MOF, and the free radical resistance was significantly improved. Cerium-based MOF has a good effect as a hydroxyl radical quencher.

[0224] (6) The thickness of the composite ion exchange membranes in Examples 19-21 and Comparative Examples 4-6 and the mass loss after Fenton reagent treatment were tested and are shown in Table 6.

[0225] Table 6

[0226]

[0227]

[0228] As can be seen from the data in Table 6, compared with the ion exchange membranes without cerium-based coordination polymers in Comparative Examples 4-6, the composite ion exchange membranes doped with cerium-based coordination polymers prepared in Examples 19-21 showed significantly reduced mass loss and significantly improved free radical resistance. PEM-21 and PEM-22 have essentially the same chemical composition, but their different thicknesses result in differences in free radical resistance. PEM-22, benefiting from its greater thickness, can delay the penetration of hydroxyl radicals to some extent, reducing the degradation of internal materials by hydroxyl radical attack. The differences in free radical resistance between C-PEM-1 and C-PEM-2, and between DC-PEM-1 and DC-PEM-2, are similar. Cerium-based polymers can improve the free radical resistance of ion exchange membranes of different thicknesses and composite ion exchange membranes, meeting the needs of more application scenarios.

[0229] (7) The resin types of the composite ion exchange membranes in Examples 22, Comparative Examples 7 and 8 are shown in Table 7 below. The IEC, water absorption rate and mass loss after Fenton reagent treatment of the composite ion exchange membranes were tested, and the results are shown in Table 6. The tensile strength, elongation at break and conductivity before and after Fenton reagent treatment of the composite ion exchange membranes were tested, and the results are shown in Table 8.

[0230] Table 7

[0231]

[0232] Table 8

[0233]

[0234] As shown in Table 7, compared with cerium oxide-doped composite ion exchange membranes, the MOF-8-doped composite ion exchange membrane exhibits higher IEC (internal exchange capacity), water absorption rate, and less mass loss, assuming the same ion exchange resin. This is because cerium oxide transforms into cerium ions under acidic conditions and cross-links with sulfonic acid, leading to a decrease in IEC and water absorption rate. Simultaneously, the sulfonic acid functional groups in MOF-8 can improve IEC and water absorption rate. Compared with the solid structure of cerium oxide, the porous structure of MOF-8 has a larger specific surface area and stronger free radical quenching activity, resulting in less mass loss and better durability in the composite ion exchange membrane.

[0235] As shown in Table 8, the composite ion exchange membrane composed of ion exchange resin, reinforcing layer, and MOF-8 exhibits good mechanical properties and electrical conductivity, making it suitable for use as a proton exchange membrane in fuel cells. After treatment with Fenton's reagent, the composite ion exchange membrane containing MOF-8 shows a lower degree of conductivity reduction and better durability. Compared with cerium oxide-doped DC-PEM-3, C-PEM-3 exhibits higher tensile strength, elongation at break, and electrical conductivity.

[0236] SEM scans were performed on the cross-sections of C-PEM-3 prepared in Example 22 before and after Fenton's reagent treatment. The results are as follows: Figure 1 and Figure 2 As shown; SEM scans were performed on the cross-sections of DC-PEM-7 prepared in Comparative Example 8 before and after Fenton's reagent treatment, and the results are shown in the figure. Figure 3 and Figure 4 As described above, due to thickness variations at different locations, the membrane thickness varies. However, compared to DC-PEM-7, C-PEM-3 shows less morphological change after Fenton's reagent treatment, and the interface between the middle ePTFE reinforcing layer and the upper and lower ion exchange resin layers remains relatively smooth. In contrast, after Fenton's reagent treatment, the interface between the middle ePTFE reinforcing layer and the upper and lower ion exchange resin layers in DC-PEM-7 becomes uneven and more susceptible to attack by hydroxyl radicals.

[0237] The power densities of C-PEM-3 and DC-PEM-7 before and after Fenton's reagent treatment were measured, and the results are as follows: Figure 5 As shown, the single-cell performance of C-PEM-3 fuel cell engine, both before and after Fenton's reagent treatment, is superior to that of DC-PEM-7. The introduction of MOF-8 not only improves the durability of the composite ion exchange membrane but also enhances its electrochemical performance, resulting in a significant overall performance improvement.

[0238] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0239] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A composite ion exchange membrane, characterized in that, It includes 90–99.99% ion exchange resin and 0.01–10% cerium-based coordination polymer, by mass percentage; The cerium-based coordination polymer is a three-dimensional porous MOF, and the organic ligand of the cerium-based coordination polymer is 4,8-disulfonnaphthalene-2,6-dicarboxylic acid; The preparation method of the cerium-based coordination polymer is as follows: cerium salt and organic ligand are dispersed in a solvent, and a hydrothermal reaction is carried out under acidic conditions. After cooling to room temperature, the polymer is obtained by filtration, washing, and drying. The molar ratio of cerium salt to organic ligand is 1:1~3.

2. The composite ion exchange membrane according to claim 1, characterized in that, The metal ions at the coordination centers of the cerium-based coordination polymer include Ce. 3+ and Ce 4+ At least one of them.

3. The composite ion exchange membrane according to claim 1, characterized in that, The three-dimensional porous MOF has a particle size of 5~800 nm and a BET specific surface area of ​​40~3000 m². 2 / g, micropore volume is 0.01~1.5 cm³ 3 / g.

4. The composite ion exchange membrane according to claim 1, characterized in that, The ion exchange resin includes at least one of perfluorosulfonic acid resin, perfluorosulfonyl imide resin, polyacid side-chain type perfluoro resin, sulfonated polytrifluorostyrene, sulfonated polysulfone, sulfonated polyarylether ketone, sulfonated polyarylether nitrile, sulfonated polyphosphazene, sulfonated polyphenylene ether, sulfonated polyimide, and sulfonated polybenzimidazole.

5. The composite ion exchange membrane according to claim 4, characterized in that, The ion exchange resin includes at least one of perfluorosulfonic acid resin, perfluorosulfonyl imide resin, polyacid side-chain type perfluoro resin, sulfonated polytrifluorostyrene, sulfonated polyarylether ketone, and sulfonated polyarylether nitrile.

6. The composite ion exchange membrane according to claim 5, characterized in that, The ion exchange resin includes at least one of perfluorosulfonic acid resin, perfluorosulfonamide resin, polyacid side-chain type perfluoro resin, and sulfonated polytrifluorostyrene.

7. The composite ion exchange membrane according to claim 1, characterized in that, The composite ion exchange membrane has a thickness of 3~500 μm and an ion exchange capacity of 0.1~4.2 mmol / g.

8. The method for preparing the composite ion exchange membrane according to any one of claims 1 to 7, characterized in that, Includes the following steps: (1) Disperse the ion exchange resin and cerium-based coordination polymer in a solvent to obtain a dispersion; (2) The dispersion obtained in step (1) is cast, poured or coated and then dried to obtain a composite ion exchange membrane.

9. The method for preparing the composite ion exchange membrane according to claim 8, characterized in that, Step (2) further includes loading the dispersion obtained in step (1) onto a reinforcing membrane and drying it to obtain a composite ion exchange membrane; the reinforcing membrane is a porous membrane.

10. The method for preparing the composite ion exchange membrane according to claim 9, characterized in that, The mass content of the reinforcing membrane is 0.1% to 90% of that of the composite ion exchange membrane, and the thickness of the reinforcing membrane is 2 to 400 μm.

11. The method for preparing the composite ion exchange membrane according to claim 9 or 10, characterized in that, The material of the reinforcing membrane includes at least one of non-fluorinated polyolefins, fluorinated polymers, and aromatic polymers.

12. The method for preparing the composite ion exchange membrane according to claim 11, characterized in that, The non-fluorinated polyolefin includes at least one of polyethylene, polypropylene, and ethylene-propylene copolymer; the fluorinated polymer includes at least one of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-propylene copolymer, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene-ethylene copolymer, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, polyvinyl fluoride, polychlorotrifluoroethylene, and ethylene-chlorotrifluoroethylene copolymer; the aromatic polymer film includes at least one of polyaryletherketone, polysulfone, polyethersulfoneketone, polybenzimidazole, polyarylamide, and polyimide.

13. The application of the composite ion exchange membrane according to any one of claims 1 to 7 in polyelectrolyte membranes in the chlor-alkali industry, proton exchange membranes for hydrogen production by water electrolysis, primary battery membranes for acidic batteries, secondary battery membranes, polyelectrolytes in supercapacitors, polyelectrolyte membranes for metal recycling batteries, or sensors.

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