Hydrophilic porous membranes and their preparation methods, ion exchange membranes, electrochemical devices

Abstract

This invention discloses a hydrophilic porous membrane and its preparation method, an ion exchange membrane, and an electrochemical device, relating to the field of electrochemical technology. The hydrophilic porous membrane comprises a porous fiber interwoven structure formed of ultra-high molecular weight polyethylene (UHMWPE), in which hydrophilic nanoparticles are dispersed, with at least some of the hydrophilic nanoparticles exposed in the pores of the porous fiber interwoven structure to give the interior of the hydrophilic porous membrane hydrophilic properties. As a reinforcing framework for the ion exchange membrane, the hydrophilic porous membrane significantly improves the interfacial compatibility between the UHMWPE material and the ion exchange resin, achieving dense filling of the ion exchange resin within the micropores of the porous framework, thereby constructing a low-torsion and continuously interconnected ion transport channel. Simultaneously, a high-strength bonding interface is formed between the reinforcing framework and the resin layer, effectively improving the interfacial peeling problem and significantly enhancing the electrochemical performance and long-term operational stability of electrochemical devices such as water electrolysis devices, fuel cells, or flow batteries.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and in particular to a hydrophilic porous membrane and its preparation method, an ion exchange membrane, and an electrochemical device. Background Technology

[0002] Ion exchange membranes (IEMs) play a crucial role in electrochemical devices. Their main function is to isolate the positive and negative electrode reactants in a battery or electrolyzer while providing an effective ion conduction channel. The realization of the function of ion exchange membranes requires membrane materials with excellent ionic conductivity, mechanical strength, dimensional stability, and chemical stability. Since reducing the membrane thickness can reduce the ohmic resistance of electrochemical devices, the "ultra-thinning" of membrane materials has become an inevitable trend as electrochemical devices pursue higher energy efficiency and higher power density.

[0003] To achieve ultrathinness while maintaining necessary mechanical integrity, using a high-strength porous framework as a reinforcing layer to prepare composite membranes has become the mainstream technical approach for ultrathin ion exchange membranes. Among numerous porous framework materials, ultra-high molecular weight polyethylene (UHMWPE) stands out due to its excellent mechanical strength, toughness, and chemical stability, making it an ideal framework for constructing "ultra-thin" and "ultra-strong" ion exchange membranes. Despite the significant advantages of the UHMWPE framework, its inherent strong hydrophobicity results in weak interfacial bonding with ion exchange resins, making it difficult for the resins to fully wet and penetrate the micro- and nano-pores within the UHMWPE framework. The discontinuous ion conduction pathways in the composite membrane degrade its electrochemical performance. Furthermore, the composite membrane formed by the UHMWPE framework and ion exchange resin is prone to delamination due to swelling and aging during long-term use, resulting in poor long-term stability of the electrochemical device. Therefore, although the superior mechanical properties of UHMWPE films have been fully demonstrated in many fields, the inherent hydrophobicity of UHMWPE films constitutes a fundamental technical bottleneck in their functional composite applications with ion exchange resins, limiting their application in electrochemical devices such as water electrolysis devices, fuel cells, and flow batteries. Summary of the Invention

[0004] This invention provides a hydrophilic porous membrane based on UHMWPE material; the ion exchange membrane with the hydrophilic porous membrane as the reinforcing skeleton has the advantages of being ultra-thin, having high mechanical strength, good ion resin wettability, and strong interfacial bonding, and is suitable for electrochemical devices such as water electrolysis devices, fuel cells or flow batteries.

[0005] The hydrophilic porous membrane provided by the present invention comprises: a porous fiber interwoven structure formed of ultra-high molecular weight polyethylene; and hydrophilic nanoparticles dispersed in the ultra-high molecular weight polyethylene, wherein at least a portion of the hydrophilic nanoparticles are exposed in the pores of the porous fiber interwoven structure.

[0006] The ultra-high molecular weight polyethylene has a weight-average molecular weight of 1 million to 15 million g / mol, and the hydrophilic nanoparticles are silica nanoparticles, metal oxide nanoparticles, or nanoparticles with hydrophilic functional groups formed on their surface. The hydrophilic functional groups are at least one of hydroxyl, carboxyl, amino, and sulfonic acid groups.

[0007] Optionally, at least one surface of the hydrophilic porous membrane is deposited with an oxide layer, which conformally covers the fiber surface of the porous fiber interwoven structure; the oxide layer is made of silicon dioxide or a metal oxide.

[0008] Optionally, at least one surface of the hydrophilic porous membrane is deposited with a metal layer, the metal layer conformally covering the fiber surface of the porous fiber interwoven structure; the metal layer is made of at least one of titanium, aluminum, nickel, copper, chromium, iron, platinum, and palladium.

[0009] Optionally, the average pore size of the porous fiber interwoven structure is 15~500nm.

[0010] Optionally, the porosity of the porous fiber interwoven structure is 30% to 90%.

[0011] The hydrophilic porous membrane provided by this invention can be prepared by the following method, including the following steps:

[0012] S1, Raw material premixing: Ultra-high molecular weight polyethylene, hydrophilic nanoparticles, plasticizers and antioxidants are mixed at a preset temperature to form a premix; the weight average molecular weight of the ultra-high molecular weight polyethylene is 1 million to 15 million g / mol, the hydrophilic nanoparticles are silica nanoparticles, metal oxide nanoparticles or nanoparticles with hydrophilic functional groups formed on the surface, and the hydrophilic functional groups are at least one of hydroxyl, carboxyl, amino and sulfonic acid groups.

[0013] S2, Extrusion: The premix is ​​extruded into a film using a twin-screw extruder to obtain a gel film; the twin-screw extruder includes, from the feeding direction to the extrusion direction, a preheating zone, a melt plasticizing zone, a homogenizing and metering zone, a melt pump, and a die; the melt plasticizing zone is configured with a temperature not lower than 80°C above the melting point of the ultra-high molecular weight polyethylene, and the shear rate of the premix is ​​1000~1500 s. -1 The outlet pressure of the melt pump shall not be lower than 2.5 MPa, and the pressure fluctuation shall not exceed 1%.

[0014] S3, Stretching: First, the gel film is subjected to biaxial synchronous stretching at a first stretch ratio at a first preset temperature, and then the gel film is subjected to biaxial synchronous stretching at a second preset temperature at a second stretch ratio; the first preset temperature is lower than the second preset temperature, and both the first preset temperature and the second preset temperature are 20°C lower than the melting point of the gel film; the first stretch ratio is less than the second stretch ratio; the stretching rate during the stretching process is 50~100mm / min;

[0015] S4, Extraction: Extracting the stretched film using an extractant;

[0016] S5, Drying and Annealing: Dry the extracted film and then anneal it to obtain a porous film with a porous fiber interwoven structure.

[0017] Optionally, the temperature of the preheating zone is 150~180℃.

[0018] Optionally, the temperature of the melt plasticizing zone is 200~230℃.

[0019] Optionally, the temperature of the homogenization metering zone is 240~250℃.

[0020] Optionally, the first preset temperature is 90~100℃, and the second preset temperature is 120~130℃.

[0021] Optionally, the first stretch ratio is 4 times, and the second stretch ratio is 8 to 12 times.

[0022] Optionally, the hydrophilic nanoparticles account for 0.5 to 10% of the total weight of the premix.

[0023] Optionally, the antioxidant is at least one of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and tris(2,4-di-tert-butylphenyl)phosphite.

[0024] Optionally, the antioxidant accounts for 0.1 to 0.8% of the total weight of the premix.

[0025] Optionally, the plasticizer is at least one of paraffin oil, naphthenic oil, dioctyl terephthalate, and methyl epoxide.

[0026] Optionally, step S5 may be followed by the step of depositing a metal layer on the surface of a porous membrane having a porous fiber interwoven structure, wherein the metal layer is made of at least one of titanium, aluminum, nickel, copper, chromium, iron, platinum, and palladium.

[0027] Optionally, after step S5, the method further includes the following steps: depositing a precursor layer on the surface of a porous membrane having a porous fiber interwoven structure, wherein the precursor layer is made of at least one of silicon, titanium, aluminum, nickel, copper, chromium, and iron; and subjecting the precursor layer to a low-temperature oxidation treatment at a temperature of 70~100°C.

[0028] The present invention also provides an ion exchange membrane, the ion exchange membrane comprising an ion exchange resin and the hydrophilic porous membrane described above; the ion exchange resin covers the surface of the hydrophilic porous membrane and fills the internal pores of the hydrophilic porous membrane, so that the hydrophilic porous membrane forms a continuous through-channel ion transport channel from one surface to the opposite surface.

[0029] Optionally, the ion exchange membrane is prepared by the following steps:

[0030] The first layer of ion exchange resin solution was coated onto the substrate;

[0031] A hydrophilic porous membrane is attached to the surface of the first layer of ion exchange resin solution. After attachment, pressure is applied to the surface of the hydrophilic porous membrane to degas the air.

[0032] After the degassing is completed, a second layer of ion exchange resin solution is coated onto the surface of the hydrophilic porous membrane to obtain a composite membrane structure.

[0033] The composite membrane structure is then dried and cured.

[0034] Optionally, the tensile strength of the hydrophilic porous membrane is 100~2000MPa.

[0035] Optionally, the thickness of the hydrophilic porous membrane is 100 nm to 15 μm.

[0036] The present invention also provides an electrochemical device, which includes the ion exchange membrane described above; the electrochemical device is a water electrolysis device, a fuel cell, or a flow battery.

[0037] The present invention has the following beneficial effects:

[0038] This invention introduces hydrophilic nanoparticles into an ultra-high molecular weight polyethylene (UHMWPE) matrix, thereby constructing a hydrophilic porous membrane with internal hydrophilicity while fully preserving the original ultrathin and high mechanical strength properties of UHMWPE films. This hydrophilic porous membrane serves as a reinforcing framework for the ion exchange membrane, significantly improving the interfacial compatibility between the UHMWPE material and the ion exchange resin. It achieves dense filling of the ion exchange resin within the micropores of the porous framework, thus constructing a low-torsion and continuously interconnected ion transport channel. Simultaneously, a high-strength bonding interface is formed between the reinforcing framework and the resin layer, effectively improving… This invention addresses the interfacial peeling problem that easily occurs in ion exchange membranes during long-term use, thereby effectively improving the electrochemical performance and long-term operational stability of electrochemical devices such as water electrolysis devices, fuel cells, or flow batteries using this ion exchange membrane. In addition, the melting point of the hydrophilic porous membrane after introducing hydrophilic nanoparticles is higher than that of pure UHMWPE film, which provides a larger thermal processing window for the processing technology of hydrophilic porous membranes. Moreover, the prepared hydrophilic porous membrane can maintain the stability of pore structure and size at higher temperatures, enabling electrochemical devices to operate stably for a long time at higher temperatures. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 The droplet contact angle test results are for a pure UHMWPE film.

[0041] Figure 2 This is a droplet contact angle test diagram of the hydrophilic porous membrane prepared in Example 1 of the present invention;

[0042] Figure 3 This is a droplet contact angle test diagram of the hydrophilic porous membrane prepared in Example 2 of the present invention;

[0043] Figure 4 AFM surface morphology of pure UHMWPE film;

[0044] Figure 5 AFM surface morphology image of the hydrophilic porous membrane prepared in Example 1 of this invention;

[0045] Figure 6 AFM surface morphology image of the hydrophilic porous membrane prepared in Example 2 of this invention;

[0046] Figure 7 The DSC test curve of the hydrophilic porous membrane prepared in Example 2 of the present invention is shown.

[0047] Figure 8 This is a SEM cross-sectional morphology image of the proton exchange membrane prepared in Comparative Example 1 of the present invention.

[0048] Figure 9 This is a SEM cross-sectional image of the proton exchange membrane prepared in Example 4 of the present invention;

[0049] Figure 10 This is a SEM cross-sectional morphology image of the anion exchange membrane prepared in Example 5 of the present invention;

[0050] Figure 11 The polarization curves of the fuel cell experimental sample and control sample in Application Example 1 of this invention are shown.

[0051] Figure 12 The polarization curves of the experimental sample and control sample of the water electrolysis device in Application Example 2 of this invention are shown.

[0052] Figure 13 The polarization curves are shown for the "GPnano Base" sample of the water electrolysis device and the sample using the "Aemion+®" commercial ion exchange membrane in Application Example 2 of this invention.

[0053] Figure 14 The polarization curves of experimental samples using hydrophilic porous membrane frameworks of different thicknesses in the water electrolysis device of Application Example 2 of the present invention are shown.

[0054] Figure 15 The CE-VE-EE efficiency test curve of the all-vanadium redox flow battery using a hydrophilic porous membrane as an ion exchange membrane as a reinforcing framework in Application Example 3 of the present invention is shown.

[0055] Figure 16 The graph shows the cycle stability test curve of the all-vanadium redox flow battery using a hydrophilic porous membrane as the reinforcing framework in Application Example 3 of the present invention.

[0056] Figure 17 This is a volume capacity-voltage relationship test curve for a vanadium redox flow battery using a hydrophilic porous membrane as an ion exchange membrane as a reinforcing framework, as shown in Application Example 3 of the present invention, corresponding to different cycle numbers. Detailed Implementation

[0057] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0058] Experimental methods in the embodiments of this invention that do not specify specific conditions are generally performed under conventional conditions and conditions described in the manual, or under conditions recommended by the manufacturer; the general equipment, materials, reagents, etc. used are commercially available unless otherwise specified.

[0059] A first aspect of the present invention provides a hydrophilic porous membrane.

[0060] The hydrophilic porous membrane provided in this embodiment of the invention includes a porous fiber interwoven structure formed of ultra-high molecular weight polyethylene and hydrophilic nanoparticles dispersed in ultra-high molecular weight polyethylene; at least some of the hydrophilic nanoparticles are exposed in the pores of the porous fiber interwoven structure.

[0061] In this embodiment of the invention, ultra-high molecular weight polyethylene refers to polyethylene with a weight-average molecular weight of 1 million to 15 million g / mol.

[0062] In this embodiment of the invention, the average pore size of the porous fiber interwoven structure is 15~500nm, and the porosity is 30%~90%.

[0063] In this embodiment of the invention, the hydrophilic nanoparticles are silica nanoparticles, metal oxide nanoparticles, or nanoparticles with hydrophilic functional groups formed on their surface. The hydrophilic functional groups are at least one of hydroxyl, carboxyl, amino, and sulfonic acid groups. The metal oxide nanoparticles include, but are not limited to, titanium dioxide nanoparticles, cerium oxide nanoparticles, zirconium oxide nanoparticles, and alumina nanoparticles, etc., which have hydrophilic surfaces. Nanoparticles with hydrophilic functional groups formed on their surface refer to nanoparticles that possess hydrophilicity through the formation of hydrophilic groups such as hydroxyl, carboxyl, amino, or sulfonic acid groups on their surface. Hydroxyl nanoparticles include not only the aforementioned silica nanoparticles and metal oxide nanoparticles, but also graphene oxide nanomaterials, hydroxyapatite, silica nanoparticles with surface-modified silane coupling agents, and other nanoparticles such as derivative composite nanoparticles with surface-modified MOF (metal-organic framework). For silica nanoparticles, metal oxide nanoparticles, or hydroxyapatite nanoparticles, their surfaces can be further modified with hydrophilic groups such as carboxyl, amino, and sulfonic acid groups through surface modification processes such as grafting to enhance surface hydrophilicity. The density of hydrophilic groups can be controlled through specific surface modification processes.

[0064] The inventor's research team has conducted in-depth research on the film-forming properties of ultra-high molecular weight polyethylene (UHMWPE) in previous work, but existing methods are only suitable for preparing basic UHMWPE films. UHMWPE has a weight-average molecular weight of 1 million to 15 million g / mol, and UHMWPE chains have high entanglement characteristics. Inorganic nanoparticles are not only difficult to lubricate and disperse effectively in the raw materials, but also pose a significant challenge to the formation of porous fiber interwoven structures with controllable pore size and porosity. Composite films are prone to matrix yielding due to stress concentration caused by inorganic nanoparticles, and the presence of inorganic nanoparticles severely limits the unentanglement and reconstruction of UHMWPE polymer chains during processing.

[0065] Therefore, this invention addresses the bottleneck problem in the composite film formation of ultra-high molecular weight polyethylene doped with inorganic nanoparticles by proposing the following method for preparing hydrophilic porous membranes, the method comprising steps S1 to S5:

[0066] S1, Raw material premix: Ultra-high molecular weight polyethylene, hydrophilic nanoparticles, plasticizers and antioxidants are mixed at a preset temperature to form a premix.

[0067] The plasticizer is one or more of paraffin oil, naphthenic oil, dioctyl terephthalate, and methyl epoxide. The plasticizer increases the mobility of the ultra-high molecular weight polyethylene molecular chains and reduces the inter-chain entanglement density. The antioxidant is one or more of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and tris(2,4-di-tert-butylphenyl)phosphite. The antioxidant is used to prevent free radical cascade reactions and ensure the stability of the polymer material at high temperatures. The hydrophilic nanoparticles account for 0.5-10% of the total weight of the premix, and the antioxidant accounts for 0.1-0.8% of the total weight of the premix. The proportion of plasticizer can be increased or decreased according to the specific type of plasticizer and the actual processing conditions.

[0068] S2, Extrusion: The premix is ​​extruded into a film using a twin-screw extruder to obtain a gel film; the twin-screw extruder includes a preheating zone, a melt plasticizing zone, a homogenizing and metering zone, a melt pump and a die in the direction from feeding to extrusion.

[0069] The preheating zone serves to raise the temperature of the premix, reduce the temperature gradient and thermal stress in the subsequent melting and plasticizing zone, and remove moisture and impurities from the premix. In some preferred embodiments, the temperature of the preheating zone is set to 150~180℃.

[0070] The melt plasticizing zone is the core functional area of ​​the twin-screw extruder. Its function is to melt the premix and uniformly disperse the added nanoparticles to form a homogeneous melt. The melt plasticizing zone is configured with a temperature not lower than 80°C above the melting point of ultra-high molecular weight polyethylene. This temperature window can significantly reduce melt viscosity, promote the lubrication and dispersion of nanoparticles, and effectively prevent polymer degradation caused by overheating. The screw metering section of the melt plasticizing zone is equipped with 3 to 4 sets of mixing elements (such as helical toothed discs or kneading blocks). Through their segmentation, recombination, and strong shearing action on the melt, they achieve the effect of breaking up particle agglomerates. The screw speed is set to 400~500 rpm, so that the system shear rate reaches 1000~1500 s. -1 This shear rate range can effectively disperse most micro- and nano-sized inorganic particles; in some preferred embodiments, the temperature of the melt plasticizing zone is set to 200~230°C.

[0071] The function of the homogenization metering zone is to homogenize the components transported in the molten plasticizing zone and to lay the foundation for accurate metering of the subsequent melt pump by setting the screw channel lead; in some preferred embodiments, the temperature of the homogenization metering zone is set to 240~250℃.

[0072] The melt pump is located in front of the die head. The outlet pressure of the melt pump should not be lower than 2.5MPa and the pressure fluctuation should not exceed 1% to eliminate the uneven discharge caused by screw pulses and avoid local aggregation of inorganic nanoparticles. The die head is the end extrusion unit, which is used to extrude the material and form a gel film.

[0073] S3, Stretching: First, the gel film is subjected to biaxial synchronous stretching at a first stretch ratio at a first preset temperature. This stage is called pre-stretching. Then, the gel film is subjected to biaxial synchronous stretching at a second stretch ratio at a second preset temperature to obtain a film with the target pore size, porosity, and thickness. The first stretch ratio is less than the second stretch ratio.

[0074] The first preset temperature is lower than the second preset temperature, and both the first and second preset temperatures are 20°C below the melting point of the gel film. Under this temperature condition, the crystalline region of ultra-high molecular weight polyethylene can provide necessary skeletal support. At the same time, since inorganic particles act as stress concentration points and induce matrix yielding, this temperature condition helps to suppress premature elastic recovery of the composite material, causing deformation to preferentially occur in the interface region between inorganic particles and the polymer matrix, thereby promoting the formation and growth of pores. In some preferred embodiments, the first preset temperature is set to 90~100°C, and the second preset temperature is set to 120~130°C. In some preferred embodiments, the first stretching ratio is 4 times, and the second stretching ratio is 8~12 times.

[0075] In this step, the stretching rate is controlled at 50~100 mm / min. This rate range provides sufficient time for the untangling and reconstruction of polymer molecular chains, which is conducive to achieving interconnection between micropores through plastic deformation, thereby forming larger pore sizes.

[0076] S4, Extraction: The stretched film is extracted using an extractant. This step is used to remove some unreacted monomers or low molecular weight substances from the film. The extractant can be a single organic solvent or multiple organic solvents depending on the target extractant. Organic solvents include, but are not limited to, n-hexane, dichloromethane, ethyl acetate, xylene, tetrachloroethane, isopropanol, diethyl ether, cyclohexane, etc. The specific type of extractant used is not limited in the embodiments of this invention. Those skilled in the art can select a suitable extractant according to the actual process or experimental conditions.

[0077] S5, Drying and Annealing: Dry the extracted membrane and then anneal it to obtain a porous membrane with a porous fiber interwoven structure. The drying step is used to remove residual organic solvents, while the annealing treatment is used to improve the stability and mechanical properties of the porous membrane. The annealing temperature can be selected from a temperature in the range of 50~150℃ according to the mechanical strength requirements of the membrane.

[0078] This invention introduces hydrophilic nanoparticles into an ultra-high molecular weight polyethylene matrix through a unique processing technique. While fully preserving the original ultra-thin and high mechanical strength properties of the ultra-high molecular weight polyethylene film, it constructs a hydrophilic porous membrane with internal hydrophilicity.

[0079] Furthermore, due to the difference in surface energy between inorganic nanoparticles and ultra-high molecular weight polyethylene, resulting in differences in the distribution of inorganic nanoparticles in the internal and surface regions of the film, as well as the encapsulation effect of ultra-high molecular weight polyethylene on inorganic nanoparticles in the surface region of the film, the surface hydrophilicity of hydrophilic porous membranes is often lower than that of the internal three-dimensional pore structure.

[0080] Therefore, in some preferred embodiments, at least one surface of the hydrophilic porous membrane is deposited with an oxide layer, which conformally covers the fiber surface of the porous fiber interwoven structure. The oxide layer is made of silicon dioxide or metal oxide. Here, "conformal coverage" means that the oxide layer is only loaded on the fiber surface without causing pore blockage, morphological damage or other effects on the porous fiber interwoven structure.

[0081] In some specific implementations, a precursor layer can be deposited on the surface of a porous membrane with a porous fiber interwoven structure using processes such as physical vapor deposition, chemical vapor deposition, or atomic layer deposition. The precursor layer is made of one or more of silicon, titanium, aluminum, nickel, copper, chromium, and iron. Then, the precursor layer is subjected to low-temperature oxidation treatment at a temperature of 70~100°C to obtain an oxide layer.

[0082] In other embodiments, since some metal materials have a certain degree of hydrophilicity, such as titanium, aluminum, nickel, copper, chromium, iron, platinum, palladium, etc., a metal layer can be deposited directly on the surface of a porous membrane with a porous fiber interwoven structure to replace the hydrophilic oxide layer in the above embodiments through processes such as physical vapor deposition, chemical vapor deposition, or atomic layer deposition.

[0083] Based on the hydrophilic porous membrane provided in the above embodiments, using the hydrophilic porous membrane as a reinforcing framework for ion exchange membranes allows the ion exchange resin to fully wet and penetrate into the micro-nano channels of the reinforcing framework, and the prepared ion exchange membrane can form a low-torsion and continuously interconnected ion transport channel.

[0084] Therefore, a second aspect of the present invention provides an ion exchange membrane comprising an ion exchange resin and the hydrophilic porous membrane provided in the above embodiments; the ion exchange resin covers the surface of the hydrophilic porous membrane and fills the internal pores of the hydrophilic porous membrane, so that the hydrophilic porous membrane forms a continuous through-channel ion transport channel from one surface to the opposite surface.

[0085] The ion exchange membrane provided in this embodiment of the invention can be prepared by the following method:

[0086] A first layer of ion exchange resin solution is coated onto the substrate; a hydrophilic porous membrane is attached to the surface of the first layer of ion exchange resin solution; after attachment, pressure is applied to the surface of the hydrophilic porous membrane to degas it; a second layer of ion exchange resin solution is coated onto the surface of the hydrophilic porous membrane after degassing to obtain a composite membrane structure; the composite membrane structure is then dried and cured.

[0087] In a preferred embodiment of the ion exchange membrane, the tensile strength of the hydrophilic porous membrane is selected to be 100~2000MPa, and the thickness of the hydrophilic porous membrane is selected to be 100nm~15μm.

[0088] Hydrophilic porous membranes, serving as a reinforcing framework for ion exchange membranes, significantly improve the interfacial compatibility between UHMWPE materials and ion exchange resins, enabling dense filling of ion exchange resins within the micropores of the porous framework, thereby constructing low-torsion and continuously interconnected ion transport channels.

[0089] A third aspect of the present invention provides an electrochemical device including the ion exchange membrane provided in the above embodiments, wherein the electrochemical device is a water electrolysis device, a fuel cell, or a flow battery.

[0090] In this embodiment of the invention, the ion exchange membrane forms a continuous ion transport channel, which can ensure the efficient and continuous conduction of ions in the electrochemical device. Furthermore, the ion exchange resin and the hydrophilic porous membrane can form a high-strength bonding interface, thereby effectively improving the long-term stability of electrochemical devices such as water electrolysis devices, fuel cells, or flow batteries.

[0091] Furthermore, in applications such as fuel cells or water electrolysis devices, the high permeability of gases such as hydrogen and oxygen in ultrathin films can lead to decreased fuel utilization, increased side reactions, catalyst poisoning, and potential safety hazards. In some preferred embodiments, hydrophilic porous membranes with catalytic metals such as platinum and palladium deposited on their surfaces can be selected as the reinforcing framework of ion exchange membranes to address these application scenarios.

[0092] Based on the above embodiments, in order to explain in detail the implementation method and beneficial effects of the technical solution of the present invention, the present invention also proposes the following specific embodiments. It should be noted that the following specific embodiments are merely exemplary and are not intended to limit the scope of protection of the present invention in any way.

[0093] Example 1

[0094] This embodiment prepares a hydrophilic porous membrane. The preparation method includes the following steps:

[0095] Step 1: Stir UHMWPE resin, TiO2 nanoparticles, plasticizer and antioxidant at 80°C to prepare a uniformly dispersed mixed solution;

[0096] Step 2: The prepared mixed solution is fed into a twin-screw extruder through a feeding device, and the temperature is controlled in stages along the extruder barrel: in the preheating zone, the temperature is raised to 150~180℃ to soften the material initially, prevent bridging, and remove some moisture; in the melting and plasticizing zone, the temperature is raised to 200~230℃ to fully melt the material and plasticize it under the shearing of the screw; in the homogenization and metering zone, the temperature is further precisely controlled at 240~250℃ to ensure consistent melt flowability; subsequently, the melt is filtered through a multi-layer filter to remove impurities and enters the coat hanger-type die head; the flow-blocking structure in the die head makes the melt pressure and flow rate uniformly distributed in the width direction, and finally it is stably extruded from the die lip to form a melt preform (i.e., gel film) with a thickness of 1mm and uniform distribution.

[0097] Step 3: Perform biaxial synchronous stretching on the gel membrane. First, at a lower temperature of 90~100℃, pre-stretch the gel membrane 4 times in both the MD (longitudinal) and TD (transverse) directions. Then, heat the gel membrane to 120~130℃. During this stage, the stretching ratio in the MD and TD directions is significantly increased to 8~12 times. The stretching rate is controlled within a low range of 50~100mm / min throughout the stretching process.

[0098] Step 4: Extract the stretched film using an extractant.

[0099] Step 5: Dry the extracted membrane and then anneal it to obtain a porous membrane with a porous fiber interwoven structure. The annealing temperature is in the range of 50~150℃.

[0100] AFM (Atomic Force Microscopy) surface morphology of pure UHMWPE porous membranes as follows Figure 4 As shown, the surface of the pure UHMWPE porous membrane exhibits a typical fiber-pore network interwoven structure, from Figure 4 A three-dimensional porous skeleton structure formed by interconnected ultra-high molecular weight polyethylene fibers can be clearly observed. The pores are relatively uniformly distributed, the fiber bundles are randomly oriented, and adjacent fibers are connected by physical entanglement points to form a continuous pore network.

[0101] The surface morphology of the UHMWPE hydrophilic porous membrane AFM after doping with nano-TiO2 in this embodiment is as follows: Figure 5 As shown, the hydrophilic porous membrane retains the basic morphological characteristics of the fiber-pore network structure of the pure UHMWPE porous membrane; from Figure 5 It can be observed that the nano-TiO2 particles are uniformly dispersed in the polymer matrix without obvious particle aggregation, indicating that the introduction of inorganic nano-oxides has not damaged the fibrous structure and porous morphology of UHMWPE, and the openness, connectivity and size distribution characteristics of the pores are well maintained. Fine granular protrusions can be observed in local areas, which are nano-TiO2 particles embedded in the surface of the polymer matrix. This morphological feature of the hydrophilic porous membrane is conducive to the full wetting, penetration and filling of the subsequent ion exchange resin solution, and provides a structural basis for the formation of a strong interfacial bond between the ion exchange resin and the reinforcing skeleton.

[0102] Droplet contact angle tests were performed on the pure UHMWPE film and the hydrophilic porous membrane prepared in this embodiment. The droplet contact angle of the pure UHMWPE film is as follows: Figure 1 As shown, the droplet contact angle reached 129.898°, indicating that UHMWPE has significant hydrophobicity; the droplet contact angle of the hydrophilic porous membrane prepared in this embodiment is as follows: Figure 2 As shown, the angle is 90.146°, which proves that the hydrophilic porous membrane prepared in this embodiment effectively improves the hydrophilicity of the UHMWPE film.

[0103] Example 2

[0104] This embodiment prepares a hydrophilic porous membrane. The preparation method is the same as in Example 1, except that this embodiment includes the following steps after step 5:

[0105] The hydrophilic porous membrane (pore size 25~35nm, porosity 40~60%) obtained in step 5 was cut into 100mm×100mm square samples. A stainless steel mesh frame was used to tension and fix the membrane edges to ensure good surface flatness. The membrane was then mounted on the rotatable substrate stage of the magnetron sputtering system. The sputtering system was equipped with a circular titanium target, and the target-substrate distance was set to 90mm. The vacuum pumping system was activated to achieve the preset background vacuum level. A preset flow rate of high-purity argon gas was introduced into the sputtering chamber, and the titanium target was pre-sputtered using a DC sputtering power supply at a sputtering power of 150 kWh. W, pre-sputtering time 5min to remove the oxide layer and adsorbed impurities on the target surface, ensuring the purity and quality of the subsequently deposited film; after pre-sputtering, adjust the sputtering power to 200W and start the substrate stage rotation function to ensure the uniformity of the film thickness; open the baffle to start formal deposition, control the titanium deposition rate to about 0.4nm / min; when the quartz crystal microbalance shows that the film thickness reaches the set value of 10nm, immediately turn off the sputtering power to terminate the deposition process; the sample is allowed to cool to about 35℃ in a vacuum environment, and then nitrogen is slowly introduced to atmospheric pressure to remove the sample.

[0106] The AFM surface morphology of the hydrophilic porous membrane prepared in this embodiment is as follows: Figure 6 As shown, the titanium metal layer on the surface forms a relatively uniform covering layer on the UHMWPE porous framework. Although a 10nm thick titanium metal layer is deposited on the surface, the porous fiber network structure of the hydrophilic porous membrane is still clearly discernible from the AFM morphology image (the porous morphology is basically the same as...). Figure 5 The UHMWPE film without a deposited titanium metal layer (as shown) indicates that the thickness of the deposited titanium metal layer is appropriately controlled, without closing or filling the pore channels; the process temperature for depositing the titanium metal layer is strictly controlled within the heat resistance range of UHMWPE (substrate temperature <80℃), thus not causing thermal damage or deformation to the microstructure of the polymer matrix; the deposited metal atoms preferentially adsorb onto high-energy sites on the surface of the polymer fibers, forming island-like or layered growth patterns, gradually covering the fiber surface without blocking the pores between fibers; this surface modification method imparts hydrophilicity to the surface of the UHMWPE porous membrane material while perfectly preserving the open pore structure and high porosity characteristics of the UHMWPE porous membrane.

[0107] The hydrophilic porous membrane prepared in this embodiment was subjected to droplet contact angle testing, such as... Figure 3 As shown, the droplet contact angle is as low as 33.867°, indicating that the hydrophilicity of the hydrophilic porous membrane with a titanium metal layer deposited on the surface is significantly improved compared with the hydrophilic porous membrane prepared in Example 1.

[0108] Combined with Examples 1 and 2 and Figures 4-6The AFM characterization results show that neither the bulk doping of nano-TiO2 nor the further deposition of a titanium metal layer on the surface of the UHMWPE porous membrane has a destructive effect on the intrinsic porous structure of the UHMWPE porous membrane. The modified composite membrane still maintains an open three-dimensional interconnected pore network, a suitable pore size distribution, and a high porosity. These structural features ensure that the ion exchange resin solution can fully wet the surface of the membrane substrate, penetrate into the pore channels, and fill the pore space during the coating process, and achieve mutual interconnection and molecular chain entanglement of the upper and lower resin layers through the pores during the wet composite process. The integrity of the porous structure is a key prerequisite for obtaining a high-quality composite ion exchange membrane, providing microstructural protection for the formation of a strong interfacial bond between the resin layer and the reinforcing framework, and achieving excellent ion conduction performance and mechanical strength.

[0109] Example 3

[0110] This embodiment prepares a hydrophilic porous membrane, and the preparation method is the same as in Example 2. The difference is that after depositing a titanium metal layer on the surface of the UHMWPE membrane, the following steps are also included:

[0111] The UHMWPE film sample with a titanium metal layer deposited on its surface was placed in an electrically heated constant temperature drying oven and subjected to low-temperature oxidation treatment under normal pressure air atmosphere. The temperature was increased to 80℃ at a rate of 3℃ / min using a programmed temperature rise mode, and then held at a constant temperature for 4 hours to allow the titanium metal layer to be fully oxidized into a TiO2 hydrophilic modified layer. After the oxidation was completed, the heating was turned off, and the sample was allowed to cool naturally to room temperature in the drying oven to obtain a hydrophilic porous membrane with TiO2 nanoparticles in the bulk phase and a TiO2 hydrophilic modified layer deposited on the surface.

[0112] Furthermore, DSC (differential scanning calorimetry) tests were performed on hydrophilic porous membranes prepared under different conditions and on pure UHMWPE porous membranes. The test results are as follows: Figure 7As shown, "Pure-PE" represents an unmodified UHMWPE porous membrane, "PE-mix-TiO2" represents a hydrophilic porous membrane with TiO2 nanoparticles doped in the bulk phase and a TiO2 layer deposited on the surface, "PE-TiO2" represents a hydrophilic porous membrane with TiO2 nanoparticles doped only in the bulk phase, and "PE-Ti-coating" represents a hydrophilic porous membrane with a Ti metal layer deposited only on the surface. The main melting peak of the unmodified UHMWPE porous membrane is generally located at about 132~135℃, while the main melting peak of each hydrophilic porous membrane shifts upward to about 142~147℃, with a melting point increase of about 10~12℃. This change is due to the uniformly dispersed inorganic nanoparticles in the bulk phase melting... During the melt-stretch-cool film formation process, the metal / metal oxide thin layer deposited by magnetron sputtering acts as both a nucleating agent and a stress transfer point, making it easier for UHMWPE molecular chains to form crystalline regions with higher regularity and larger grain size after stretching and orientation. This reduces the proportion of defects and loose chain segments within the crystalline regions and at the crystal / amorphous interface. On the other hand, the metal / metal oxide thin layer deposited by magnetron sputtering forms a gradient constraint structure similar to a "hard shell-soft core" in the near-surface region of the pore wall through physical entanglement and interfacial interaction with the UHMWPE chain segments. This significantly suppresses the chain folding slip and crystal disintegration process in the crystalline region, allowing for overall melting only at higher temperatures. This results in a systematic upward shift and narrowing of the melting peak on the DSC curve.

[0113] The significant improvement in melting point and thermal stability is a key advantage of the hydrophilic porous membrane and ion exchange membrane of this invention in subsequent research and application stages. On the one hand, the higher melting point provides a larger thermal process window for processes such as wet composite coating, drying and curing, and subsequent annealing at 120~140℃. The modified UHMWPE skeleton can still maintain the stability of pore structure and size at higher temperatures, and is not prone to thermal shrinkage, pore collapse, or significant decline in mechanical properties, which is conducive to obtaining composite ion exchange membranes with uniform thickness and no interfacial delamination. On the other hand, in actual working conditions such as fuel cells, water electrolysis devices, and flow batteries, membrane electrode assemblies often operate at 50~80℃ or even higher temperatures for a long time. The higher melting point and crystalline thermal stability can effectively suppress the softening, creep, and thermal shrinkage of the reinforcing skeleton under the action of electrochemical reaction exothermics and local hot spots, ensuring that the interfacial bonding between the ion exchange resin layer and the reinforcing skeleton remains intact for a long time. This improves the dimensional stability, mechanical reliability, and cycle life of the membrane assembly, and significantly expands the usable temperature range and safety margin of the ion exchange membrane in high temperature, high current density, and harsh industrial environments.

[0114] Example 4

[0115] This embodiment prepares a proton exchange membrane.

[0116] The hydrophilic porous membrane prepared in Example 2 was selected as the reinforcing framework. A proton exchange resin layer was coated on both sides of the hydrophilic porous membrane using a wet composite coating process to form a composite membrane structure with proton conduction function. Specifically, this example utilizes the fluidity and adhesion properties of the resin solution in a wet state. Through multiple consecutive coating operations, in-situ composite bonding at each interface is achieved before the solvent has completely evaporated, thereby obtaining a composite structure with strong interfacial bonding and no macroscopic delamination defects. The preparation process includes the following steps:

[0117] Step 1: Select a flat substrate. Before use, wipe the substrate with acetone and anhydrous ethanol (or isopropanol) in sequence to remove surface oil, organic residue and particulate contaminants. Finally, wipe it dry with a lint-free cloth or blow it with high-purity nitrogen until there is no solvent residue on the surface. To prevent the resin from sticking to the substrate after curing, a thick polytetrafluoroethylene film can be laid on the surface of the substrate as an isolation layer, or the surface of the substrate can be fluorosilaneized to reduce surface energy.

[0118] Step 2: The scraping device uses a scraper applicator to perform the first scraping operation on the treated substrate. The prepared perfluorosulfonic acid resin solution is spread along the width of the substrate to form a continuous solution embankment at the starting end. The width of the solution embankment should cover the entire scraping width. The amount of solution used is calculated and determined based on the scraping area, scraper gap, and solution solid content. The scraper is started to scrape along the length of the substrate. During the scraping process, the scraper movement speed should be kept constant, the scraper pressure should be uniform, and the contact line between the scraper and the substrate should be parallel to the edge of the substrate to ensure the formation of a wet resin layer with uniform thickness and a smooth surface.

[0119] Step 3: After the first coating is completed, the film application operation must be completed within a strictly controlled time window. This time window is determined by the solvent evaporation kinetics of the perfluorosulfonic acid resin, requiring the resin layer surface to remain wet, the internal solution to remain fluid, and the surface to have sufficient adhesion. When applying the film, start by contacting the wet resin layer with the hydrophilic porous membrane from one end, and gradually unfold it to the other end using a rolling application method. After the film is applied, immediately use a soft rubber squeegee, silicone rubber roller, or polyurethane roller to roll or scrape from the center area of ​​the film to the surrounding edges to remove air bubbles and excess resin solution between the interfaces, so that the membrane substrate is fully immersed in the resin solution and achieves tight adhesion. Repeat the degassing process multiple times, changing the rolling direction each time to ensure that air bubbles are completely removed.

[0120] Step 4: Pour perfluorosulfonic acid resin solution along the starting end onto the upper surface of the hydrophilic porous membrane to form a solution dam, and then perform a second coating using a scraper. The coating speed and angle should be consistent with the first coating. This step should be completed while the lower resin solution is still wet and the membrane substrate has not yet experienced shrinkage stress due to solvent evaporation. After coating, the lower wet resin and the upper resin interpenetrate, diffuse, and mix at the porous structure of the membrane substrate, forming a continuous resin phase that runs through the membrane thickness direction. This ensures molecular chain entanglement and interfacial adhesion between the upper and lower resin layers and the membrane substrate, as well as between the upper and lower resin layers themselves, thereby obtaining a composite membrane structure without obvious interfaces.

[0121] Step 5: First, allow the composite membrane to evaporate naturally in a still air environment at room temperature and normal pressure. During this stage, most of the low-boiling-point solvents gradually evaporate through surface evaporation and internal diffusion, and the composite membrane gradually changes from a wet state to a semi-dry state. Then, transfer the composite membrane along with the substrate to a forced-air drying oven or vacuum drying oven for heating and drying. First, remove most of the residual solvent at a lower temperature, and then raise the temperature to a higher temperature to completely remove the solvent and cure the resin to form a stable solid structure. After cooling to room temperature, peel the composite membrane off the substrate. The peeled composite membrane can then undergo subsequent heat treatment annealing and other processes as needed.

[0122] Example 5

[0123] This embodiment prepares an anion exchange membrane. The preparation steps are the same as in Example 4, except that the perfluorosulfonic acid resin is replaced with anion exchange resin.

[0124] Comparative Example 1

[0125] This comparative example prepared a proton exchange membrane. The preparation steps were the same as in Example 4, except that the hydrophilic porous membrane used as the reinforcing framework was replaced with a pure UHMWPE membrane.

[0126] The cross-sectional SEM morphology of the composite membrane prepared in Comparative Example 1 is as follows: Figure 8As shown, the composite membrane exhibits a distinct three-layer structure: an upper proton exchange resin layer, a middle UHMWPE reinforcing framework layer, and a lower proton exchange resin layer. The overall thickness of the composite membrane is approximately 12 μm, with the UHMWPE framework layer being approximately 2 μm thick, and the upper and lower proton exchange resin layers being approximately 5 μm and 2 μm thick, respectively. Obvious cracks or voids (dark stripes or pore areas in the figure) are observed within the UHMWPE reinforcing framework layer. The formation of these cracks is mainly attributed to insufficient wetting of the hydrophobic UHMWPE reinforcing framework by the resin solution. Pure UHMWPE material exhibits strong hydrophobic properties; although the resin solution can... While the resin solution can wet the membrane surface and penetrate the surface pores to a certain extent, due to the significant difference in interfacial tension and chemical incompatibility between UHMWPE and perfluorosulfonic acid resin, the resin solution cannot fully penetrate into the microporous structure inside the framework, especially the pore channels with small pore size (30~35nm) or high tortuosity. Therefore, during the resin curing process, the solvent evaporation causes the resin volume to shrink, and the pore areas that are not fully filled by the resin form macroscopically visible cracks or voids. The presence of these cracks not only destroys the continuity and compactness of the composite membrane structure, but also becomes an obstacle to ion transport and a point of mechanical stress concentration, which seriously affects the ionic conductivity, mechanical strength and dimensional stability of the composite membrane.

[0127] from Figure 8 The SEM cross-sectional morphology shown also reveals a significant difference in the interfacial bonding state between the reinforcing skeleton and the upper and lower resin layers: the lower interface (the contact interface between the bottom resin and the skeleton) exhibits a clearer boundary line, with obvious gaps or delamination visible at the interface, indicating weak adhesion between the lower resin and the UHMWPE skeleton and poor interfacial bonding. This obvious interface is due to the repulsive effect of the hydrophobic UHMWPE surface on the resin solution, causing the resin to easily detach from the skeleton surface or generate interfacial stress during curing, resulting in interfacial separation. In contrast, the upper interface (the contact interface between the upper resin and the skeleton) appears... The interface is relatively blurry, and the boundary is not as clear as the lower interface. This difference may be related to the operation sequence of the wet lamination process: after the first coating to form the lower resin layer, the film is applied. At this time, the lower resin layer has partially lost its fluidity, and the contact between the film and the resin is mainly physical bonding. However, during the second coating, the upper fresh resin solution has better fluidity, and under the pressure of the doctor blade, a certain degree of penetration may occur, making the upper interface relatively dense. However, even if the upper interface appears to have good interfacial bonding, due to the inherent hydrophobicity of UHMWPE, there are still problems of poor wetting and insufficient adhesion at the interface, which can easily lead to interface debonding or delamination failure during service.

[0128] The cross-sectional SEM morphology of the ion exchange membrane prepared in Example 4 is as follows: Figure 9As shown, the hydrophilic porous membrane after dual hydrophilic modification treatment with bulk doping of nano-TiO2 and surface deposition of a titanium metal layer exhibits a dense and uniform internal structure, with no obvious cracks, voids, or large-scale defects observed. This significant improvement is attributed to the hydrophilic modification, which greatly enhances the wettability and permeability of the resin solution to the UHMWPE reinforced framework. The doping of nano-TiO2 introduces a hydrophilic inorganic phase into the bulk framework, and the abundant hydroxyl groups on the TiO2 surface can form hydrogen bonds with water molecules or polar solvents, reducing the hydrophobicity within the framework. More importantly, the surface-deposited titanium metal layer forms a continuous hydrophilic coating on the framework surface, further enhancing its hydrophilic properties. With its high surface energy (titanium's surface energy is approximately 50-70 mN / m, far exceeding that of UHMWPE), it exhibits excellent hydrophilicity. This hydrophilic modification strategy, which considers both the surface and the interior, allows the perfluorosulfonic acid resin solution to spread rapidly on the surface of the skeleton during the wet composite coating process. Driven by capillary action and concentration gradient, it quickly penetrates into the porous structure of the UHMWPE-reinforced skeleton, fully filling the pore spaces. The complete wetting of the UHMWPE-reinforced skeleton by the resin ensures that no unfilled voids are left inside the skeleton during the solvent evaporation and curing process, thereby avoiding the generation of cracks and obtaining a composite film with a dense structure and good continuity.

[0129] from Figure 9 The SEM cross-sectional morphology shown also reveals that the interface between the modified UHMWPE framework and the upper and lower proton exchange resin layers exhibits a blurred transition characteristic. This interface blurring phenomenon is direct evidence of excellent interfacial bonding, indicating that the resin and framework achieve good mutual wetting and interfacial fusion. Specifically, the surface hydrophilic modification layer (hydrophilic metal or metal oxide) serves as the interfacial compatibility layer between the framework and the resin. Its hydrophilic surface can generate strong hydrogen bonding and dipole-dipole interactions with polar groups such as sulfonic acid groups (-SO3H) and ether bonds (-O-) in the perfluorosulfonic acid resin, significantly improving the interfacial adhesion energy. At the same time, during the wet composite preparation of the ion exchange membrane, the upper and lower resin solutions permeate, diffuse, and mix with each other through the interconnected pores of the framework. The resin molecular chains form a continuous network structure inside the pores. This molecular-scale interpenetration and entanglement further strengthens the interfacial bonding.

[0130] In particular, unlike the asymmetry of pure UHMWPE skeleton composite membranes, which have a distinct lower interface and a relatively blurred upper interface, the modified skeleton composite membrane exhibits good bonding at both the upper and lower interfaces. This is due to the fact that hydrophilic modification eliminates the repulsion of the resin on the skeleton surface. Whether it is the lower interface formed after the first coating or the upper interface formed after the second coating, the resin can fully wet the skeleton surface and form a strong bond. This symmetrical and uniform bonding at the upper and lower interfaces is beneficial for the uniform stress distribution of the ion exchange membrane during service, avoiding preferential failure caused by asymmetric interface strength.

[0131] The cross-sectional SEM morphology of the anion exchange membrane prepared in Example 5 is shown below. Figure 10 As shown, the overall thickness of the composite membrane is approximately 40 μm, with a dense and complete structure. No obvious cracks or large pore defects were observed inside the framework layer. The interface between the reinforcing framework and the anion exchange resin layer is blurred, but the bonding is tight. The anion exchange resin is typically based on a quaternary ammonium salt group ( The polymer system has similar polarity and hydrophilicity to perfluorosulfonic acid resin, but its chemical structure is different. SEM cross-sectional morphology shows that the hydrophilically modified UHMWPE skeleton can also achieve good interfacial compatibility and wetting filling with anion exchange resin. This verifies that the hydrophilic modification strategy proposed in this invention has universality and is applicable not only to the preparation of proton exchange membranes, but also to the preparation of other types of ion exchange membranes such as anion exchange membranes, providing a technical basis for the diversified application of composite ion exchange membranes.

[0132] Application Example 1

[0133] This application example assembles a membrane electrode assembly for a fuel cell based on the proton exchange membrane provided in Example 4 and performs relevant performance tests.

[0134] Specifically, the membrane electrode assembly is prepared by assembling the membrane electrode, the gas diffusion layer coated with the catalyst, and the proton exchange membrane provided in Example 4 according to the structural layout of anodic gas diffusion layer-anodic catalyst layer-proton exchange membrane-cathode catalyst layer-cathode gas diffusion layer.

[0135] The polarization curve test was performed using the constant current step scan method. Starting from the open circuit voltage state, the current density applied to the battery was gradually increased. At each current density set point, the current was kept constant until the battery voltage reached a steady state, and the steady state voltage value at that point was recorded. The test samples included control samples and experimental samples. The control samples used the proton exchange membrane provided in Comparative Example 1, and the experimental samples used the proton exchange membrane provided in Example 4.

[0136] The polarization curves of the experimental sample and the control sample are as follows: Figure 11As shown, on the polarization curve, the ohmic overpotential mainly manifests as a linear voltage drop in the medium current density region, i.e., the range of 0.2 to 1.0 amperes per square centimeter. In this medium current density region, the voltage of the experimental sample is significantly higher than that of the control sample. Linear fitting of the polarization curves of the experimental and control samples in this region yields their respective areal resistivity. The areal resistivity of the experimental sample is significantly lower than that of the control sample, indicating that hydrophilic treatment effectively reduces the proton conduction resistance of the ion exchange membrane. The specific principle is as follows: First, hydrophilic modification enhances the bond between the UHMWPE framework and the perfluorosulfonic acid resin. Interfacial compatibility and bonding strength promote the full wetting of the UHMWPE skeleton by the perfluorosulfonic acid resin and its uniform penetration and filling within the pores. Secondly, good interfacial bonding eliminates microscopic voids and defects at the interface between the reinforcing layer and the ionomer, significantly reducing the conduction resistance when protons pass through the interface. Thirdly, the hydrophilically modified UHMWPE skeleton provides favorable nucleation sites and anchoring points for the formation of sulfonic acid group ion clusters and the construction of hydration channels in the perfluorosulfonic acid resin, promoting the establishment of a continuous proton conduction network throughout the film thickness direction, reducing the tortuosity of the proton conduction path, and increasing the effective proton conduction cross-sectional area.

[0137] Concentration overpotential mainly occurs in the high current density region of the polarization curve, typically manifesting significantly when the current density exceeds 1.0 amperes per square centimeter. This overpotential originates from insufficient mass transfer rate of reactants to the electrode surface or a limited rate of product water removal from the electrode. Under high current density operating conditions, the rate at which the electrode electrochemical reaction consumes reactants is rapid. If the pore structure of the gas diffusion layer or catalyst layer cannot replenish fresh reactants to the reaction sites in a timely manner, the reactant concentration at the electrode surface will be significantly lower than the bulk concentration, resulting in a concentration gradient and concentration overpotential. Simultaneously, at high current densities, the cathode catalyst layer rapidly generates a large amount of product water. If this water cannot be promptly removed through the gas diffusion layer and proton exchange membrane, it will accumulate in the pores of the catalyst layer and gas diffusion layer, blocking gas transport channels and further exacerbating mass transfer resistance. This phenomenon is known as the flooding effect. Figure 11As shown in the polarization curves, the concentration overpotential manifests as a sharp, nonlinear voltage drop in the high current density region, with the curve exhibiting a distinct downward bend. Comparison of the performance of the experimental and control samples in the high current density region reveals that the voltage drop rate of the experimental sample is significantly lower than that of the control sample, and the limiting current density of the control sample (i.e., the current density corresponding to a voltage drop to 0.3 volts) is significantly higher than that of the control sample. These results indicate that the hydrophilic modification of the UHMWPE reinforcing skeleton has a positive impact on the performance stability of the composite membrane under high current density conditions. The high interfacial bonding force of the hydrophilic modified UHMWPE reinforcing skeleton ensures that the composite membrane maintains better structural integrity and dimensional stability during high current density operation, resisting the mechanical stress generated by high-speed gas flow and liquid water transport, preventing delamination or interfacial slippage between the reinforcing layer and the ionomer, and maintaining the continuity of the proton conduction network and water transport channels. The sufficient filling of perfluorosulfonic acid resin ensures that there are no local weak points or structural defects within the composite membrane, avoiding uneven distribution and local accumulation of water within the membrane, thereby reducing the concentration overpotential and improving the stability and ultimate output capability of the battery under high load conditions.

[0138] Maximum power density is the most critical indicator for evaluating the actual output capability of a fuel cell. By multiplying the voltage at each test point on the polarization curve by the corresponding current density, the power density-current density curve can be obtained (not shown in the attached figure). The maximum power density of the experimental sample is significantly higher than that of the control sample, and the current density corresponding to the maximum power density is also higher. This indicates that the experimental sample can operate stably and output greater power at a higher current density. The improvement in maximum power density is not only due to the reduction in the ohmic resistance of the ion exchange composite membrane, but also to the reduction in concentration overpotential and the increase in limiting current density.

[0139] Depend on Figure 11 The polarization curve test results show that the present invention significantly improves the performance of the composite proton exchange membrane in fuel cells by hydrophilic modification of the UHMWPE porous membrane reinforcement skeleton, providing an effective technical approach for the industrial application of UHMWPE porous membrane in fuel cell proton exchange membranes.

[0140] Application Example 2

[0141] This application example assembles a membrane electrode assembly for an electrolytic water device based on the anion exchange membrane provided in Example 5 and conducts relevant performance tests.

[0142] Specifically, the membrane electrode assembly is prepared using a catalyst-coated substrate technology. The gas diffusion layer coated with the catalyst is assembled with the anion exchange membrane to be tested according to the structure of anodic gas diffusion layer-anodic catalyst layer-anion exchange membrane-cathode catalyst layer-cathode gas diffusion layer to obtain the membrane electrode assembly.

[0143] The prepared membrane electrode assembly was installed in the electrolyzer test fixture. The operating conditions for the water electrolysis performance test were set as follows: the electrolyzer temperature was controlled at the preset temperature, the electrolyte was a 1M KOH aqueous solution, and the electrolyte circulation flow rate was 50mL / min. The newly prepared membrane electrode assembly needed to be activated before the formal test. The activation procedure was to run at a preset constant current density for 2 hours under the above operating conditions, and then perform a current density cyclic scan within a preset current density range until the electrolyzer performance was stable.

[0144] The polarization curve test results are as follows Figure 12-14 As shown, the experimental samples used the anion exchange membrane provided in Example 5, while the control samples used anion exchange membranes made by filling unmodified UHMWPE porous membranes with anion exchange resin. Polarization curves were tested on experimental samples with three different anion exchange membrane thicknesses of 1.5 μm, 3 μm, and 5 μm. Furthermore, the "GPnano Base" sample is a high-performance anion exchange membrane obtained by further improving and optimizing the formulation, process, and structural design based on the anion exchange membrane provided in Example 5. Improvements included optimizing the modification method, controlling the degree of modification, selecting the optimal reinforcing layer thickness, and optimizing the type and content of ionomers. The "Aemion+®" sample using the commercially available "Aemion+®" anion exchange membrane served as the performance benchmark sample for comparing with the "GPnano Base" sample.

[0145] See Figure 12The comparison of polarization curves between experimental and control samples directly verified the effectiveness of hydrophilic modification of the UHMWPE porous reinforcing framework. Unmodified UHMWPE porous reinforcing frameworks are hydrophobic and chemically inert, exhibiting significant interfacial phase separation with the hydrophilic anion exchange ionomers. This leads to increased ion conductivity at the interface, uneven filling of the ionomers within the porous membrane pores, and difficulty in forming a continuous and effective ion conduction network. After hydrophilic modification, the hydrophilic groups introduced onto the surface of the UHMWPE porous reinforcing framework significantly enhance the interfacial interaction with the anion exchange resin, including electrostatic interactions, hydrogen bonding, and van der Waals forces. The surface promotes uniform penetration and full filling of anion exchange resin within the porous membrane pores, reducing interfacial voids and defects, thereby lowering interfacial resistance. The hydrophilic surface also provides nucleation sites for the formation and connection of ion clusters in the anion exchange resin, promoting the construction of continuous ion conduction channels throughout the membrane thickness. In high current density regions, the modified reinforcing layer exhibits better structural stability. The enhanced interfacial bonding force from the modified surface enables the composite membrane to maintain interfacial integrity under high-speed bubble flow and shear stress, preventing delamination of the ionomer from the reinforcing layer. Furthermore, the hydrophilic surface improves the wetting properties and mass transfer performance of the anion exchange membrane, which is beneficial for OH-. - Rapid ion transport and timely bubble removal; Figure 12 The test results shown fully demonstrate that the hydrophilic modification of the UHMWPE porous reinforced framework is the core factor in improving the water electrolysis performance of the composite anion exchange membrane.

[0146] See Figure 13A comparison of the polarization curves of the "GPnano Base" sample and the commercial "Aemion+®" sample comprehensively demonstrates the performance advantages of the present invention over commercial products. Through further formulation optimization, process improvement, and structural design, the GPnano Base sample achieves a significant performance improvement, with its polarization curve being significantly superior to that of the commercial "Aemion+®" sample. Throughout the entire current density range, the operating voltage of the "GPnano Base" sample is lower than that of the "Aemion+®" sample, indicating that GPnano Base has lower ion conduction resistance and better mass transfer performance. Within the actual operating current density range, the "GPnano Base" sample exhibits a significant voltage advantage over the "Aemion+®" sample, corresponding to higher energy conversion efficiency. In the high current density region, the "GPnano Base" sample demonstrates superior mass transfer performance and structural stability, with a flatter upward trend in the polarization curve and a higher limiting current density, proving its stronger resistance to concentration polarization and mechanical stability under harsh operating conditions. The performance advantage of the “Base” sample is attributed to the perfect synergy between the hydrophilic modified UHMWPE reinforcing framework and the ionomer. The hydrophilic modified UHMWPE reinforcing framework provides excellent interfacial compatibility, mechanical support and mass transfer channels, while the optimized ionomer composition provides an efficient ion conduction network.

[0147] Considering the inherent advantages of UHMWPE-reinforced framework in terms of raw material cost, preparation process, mechanical strength, and chemical stability, as well as the superior electrochemical performance of the "GPnano Base" sample compared to commercial products, the technical solution of this invention not only achieves a performance breakthrough in ion exchange membranes for water electrolysis devices but also establishes a competitive advantage in terms of cost-effectiveness. The excellent performance of the "GPnano Base" sample proves that the composite ion exchange membrane technology based on hydrophilically modified UHMWPE porous UHMWPE-reinforced framework has surpassed the performance level of existing commercial products. It provides an advanced technical route for hydrogen production through anion exchange membrane water electrolysis that is low-cost, high-performance, and scalable, and has significant strategic importance and application value for promoting the industrial application of green hydrogen production technology and reducing the cost of hydrogen energy.

[0148] See Figure 14 The polarization curves of composite ion exchange membranes prepared with hydrophilically modified UHMWPE porous reinforced frameworks of three different thicknesses (1.5 μm, 3 μm, and 5 μm) revealed the intrinsic correlation between the thickness of the reinforcing layer and the water electrolysis performance; increasing the thickness of the reinforcing layer inevitably prolongs the OH... -The transport path of ions leads to an increase in ion conduction resistance, which manifests as an increased slope in the medium current density region of the polarization curve. However, increasing the thickness of the reinforcing layer simultaneously improves the mechanical strength, tear resistance, and dimensional stability of the composite membrane, enabling it to maintain structural integrity and resist shear stress and mechanical impact generated by bubble flow under harsh conditions of high current density and high gas evolution rate. While an excessively thin reinforcing layer has a lower ion resistance, its mechanical strength is insufficient to support long-term stable operation, making it prone to local deformation, pinhole formation, or mechanical damage under high load conditions, resulting in ionized polymer loss or gas cross-permeation. Conversely, an excessively thick reinforcing layer, while having excessive mechanical properties, results in a significant reduction in energy conversion efficiency due to excessive ion resistance, rendering it economically unfeasible. Based on the current density range, operating time requirements, and cost constraints of the specific application scenario, the optimal reinforcing layer thickness can be selected to achieve a synergistic optimization of technical performance and economy.

[0149] Application Example 3

[0150] This application example demonstrates the assembly of a vanadium redox flow battery cell based on the proton exchange membrane provided in Example 4, and related performance tests were conducted.

[0151] The proton exchange membrane to be tested is cut into square membrane pieces to serve as the separator component in the battery cell. The battery cell includes a graphite bipolar plate, a carbon felt electrode, a proton exchange membrane, a current collector, an end plate, and a sealing gasket, and vanadium sulfate is used as the vanadium source.

[0152] Figure 15 The paper presents the variation of coulombic efficiency (CE), voltage efficiency (VE), and energy efficiency (EE) of the vanadium redox flow battery cell constructed based on a proton exchange membrane with a hydrophilically modified UHMWPE reinforced framework under different charge and discharge current densities. The horizontal axis represents the charge and discharge current density (A·cm). -2 The vertical axis represents the corresponding efficiency (%). As can be seen from the figure, the three efficiency curves show obvious differentiation and different dependencies within the current density range under investigation, which fully reflects the comprehensive behavior of the system in terms of charge transfer, ion selective transport and voltage loss.

[0153] First, the coulombic efficiency (CE) curve shows that throughout the entire test current density range, CE remains at a high and essentially constant level, with the curve nearly a flat horizontal line exhibiting only minimal fluctuations. This indicates that the active species (vanadium ions in different valence states) at the positive and negative electrodes in the electrolyte can achieve highly reversible redox transformations during charge and discharge, with the active material almost completely participating in the reaction in each cycle without irreversible loss. More importantly, CE is insensitive to changes in current density, suggesting that even under high current density conditions, the cross-permeation of vanadium ions by the ion exchange membrane remains... It maintains effective suppression, with side reactions (such as asymmetric side reactions or self-discharge processes) accounting for only a very low proportion. Combined with the aforementioned SEM / AFM analysis of the ion exchange membrane structure, this excellent and robust CE performance can be attributed to the following two aspects: First, the hydrophilic UHMWPE porous reinforced framework, through the doping of bulk hydrophilic nanoparticles and the construction of a surface hydrophilic layer, achieves uniform penetration and dense filling of the ion exchange resin within the pores, thereby significantly reducing macroscopic cracks and microscopic defect channels; Second, the ion exchange membrane forms a continuous and highly selective ion conduction network along its thickness direction, effectively suppressing H+ ions. + / H3O + or OH - While maintaining high conductivity, it provides effective physical and static electrical isolation for vanadium ions with large radius and multiple valence states. Therefore, under different load conditions, active ions mainly achieve reversible valence state transformation through electrode reactions, rather than mixing and self-discharging through ion exchange membranes, which fundamentally ensures that the high coulombic efficiency of the flow battery is close to constant.

[0154] Unlike the almost constant trend of CE, voltage efficiency (VE) exhibits an approximately linear decrease with increasing current density. At low current densities, VE is at a relatively high level, indicating that the battery's terminal voltage is close to the thermodynamically reversible voltage and the voltage loss is small. As the current density gradually increases, VE gradually decreases, indicating that the contributions of ohmic polarization and concentration polarization to the terminal voltage gradually increase. Since the definition of VE essentially reflects the ratio of the average discharge voltage to the average charge voltage, its decrease directly corresponds to the increase in the total voltage loss of the system. Figure 15 The voltage efficiency (VE) decreases almost linearly with increasing current density, indicating that within the tested current density window, the battery is mainly controlled by ohmic internal resistance and moderate mass transfer polarization, and has not yet entered a severely mass transfer-limited region. Furthermore, although VE inevitably decreases with increasing current density, it remains at a high level throughout the entire test range, and the rate of decrease is relatively gentle. This indicates that the composite membrane of the present invention significantly reduces the ion conduction resistance in the thickness direction of the ion exchange membrane and the contact resistance at the electrode / membrane interface. This suggests that the internal structure of the ion exchange membrane is dense and uniform, without large-scale local high-resistance regions, thereby effectively slowing down the rate of voltage efficiency degradation.

[0155] The trend of the energy efficiency (EE) curve is basically consistent with that of VE, which is theoretically reasonable: EE is determined by the product of CE and VE, and in this system, CE remains basically constant and close to 100%, so the change of EE is almost entirely determined by VE.

[0156] comprehensive Figure 15 The three efficiency curves shown lead to the following conclusions: First, within the studied current density range, CE hardly changes with current density, consistently remaining at a high level close to the theoretical upper limit. This indicates that the ion exchange membrane prepared in this embodiment of the invention has excellent suppression of vanadium ion cross-permeation, effectively suppressing side reactions and self-discharge processes, resulting in extremely high utilization of active species. Second, VE decreases linearly with current density but remains at a relatively high overall level, indicating that the battery voltage loss is mainly contributed by controllable ohmic resistance and moderate mass transfer polarization. The composite membrane of this invention significantly reduces intramembrane ion transport resistance and interfacial contact resistance, enabling it to maintain a high operating voltage even at higher current densities. Third, EE... The decrease is mainly controlled by VE, while the negative impact of CE is negligible. This result once again confirms from the perspective of energy utilization the effectiveness of the ion exchange membrane prepared in this embodiment of the invention in inhibiting cross-permeation of active species and improving coulombic efficiency. The ion exchange membrane prepared in this embodiment of the invention not only has the advantage of high efficiency at low current density, but also can maintain stable and considerable CE, VE and EE under higher current density conditions, achieving a balance between high power density and high energy efficiency. This characteristic is particularly critical for vanadium redox flow batteries in high-power, fast charge and discharge applications, indicating that the ion exchange membrane provided by this invention has outstanding application potential and significant comprehensive performance advantages in practical engineering energy storage systems.

[0157] Figure 16 The results show a single vanadium redox flow cell at a fixed current density (160 mA·cm). -2 The volumetric discharge capacity changes with the number of cycles during approximately 500 consecutive charge-discharge cycles. It can be seen that the volumetric discharge capacity remains stable throughout the test, with only minor random fluctuations. The coulombic efficiency of the battery reaches a high level close to 100%, and there is no trend of systematic decay with the increase of the number of cycles. By the end of the 500th cycle, the coulombic efficiency is still close to 100%, indicating that under long-term repeated charge-discharge conditions, the redox process of active vanadium species in the battery is highly reversible, and almost no observable irreversible side reactions or loss of active materials occur.

[0158] Combining the aforementioned SEM / AFM structural characterization and vanadium barrier mechanism analysis of ion exchange membranes, Figure 16The results show that the ion exchange membrane prepared in this embodiment of the invention has excellent inhibition of cross-permeation of vanadium ions with different valence states, greatly reducing coulombic losses caused by self-discharge and mixing potential; the bulk nano-oxide doping and the surface hydrophilic layer synergistically achieve dense filling and strong interfacial bonding of ion exchange resin in the UHMWPE framework channels, and the membrane structure does not show obvious deterioration or new defect channels during long-term cycling, thus ensuring stable selective proton transport; at 160 mA·cm -2 At a representative operating current density in this project, the battery exhibits a coulombic efficiency close to 100% and excellent cycle stability, proving that the ion exchange membrane provided in this embodiment of the invention can fully meet the stringent requirements of vanadium redox flow battery for long-term operation in terms of vanadium blocking performance and chemical stability, and has significant advantages in high reliability and long lifespan in the vanadium redox flow battery system.

[0159] Figure 17 Typical charge-discharge curves (voltage-capacity curves) of vanadium redox flow battery cells at cycles 1, 100, 200, 300, 400, and 500 were compared. The figures show that the charging curves at each cycle stage highly overlap across the entire capacity range, with only slight differences near the charging cutoff capacity. This indicates that the voltage rise behavior and polarization characteristics of the battery remain relatively stable during charging as the cycle progresses. Similarly, the discharge curves at each cycle stage maintain good overlap in the main capacity range, with only slight differences at the end of discharge. High-cycle-number samples show a slightly earlier voltage drop at the end of discharge, but the overall difference is small, with no significant plateau contraction or premature failure. The area enclosed by the charge-discharge curves (corresponding to energy loss) changes minimally with different cycle numbers, and the starting voltage and cutoff capacity of the curves are almost identical, indicating that the usable capacity and voltage efficiency of the battery remain basically stable within the charge-discharge cycle range of 1 to 500 cycles.

[0160] comprehensive Figure 16 , 17The test results shown lead to the following conclusions: During a 500-cycle process, the vanadium redox flow battery supported by the ion exchange membrane provided in this embodiment of the invention did not exhibit significant capacity decay or increased voltage polarization. The high overlap of the charge-discharge curves at different cycle stages indicates that the electrode reaction kinetics, membrane ion conduction impedance, and electrolyte composition within the battery remain stable during long-term operation, without significant loss of active materials, electrode deactivation, or membrane structure degradation. Under the protection of the ion exchange membrane provided in this embodiment of the invention, vanadium species cross-permeation is effectively suppressed, the electrolyte composition remains relatively balanced, and the electrode / membrane interface structure and pore transport pathways do not undergo substantial degradation under hundreds of charge-discharge stresses. Therefore, the ion exchange membrane based on the hydrophilic modified UHMWPE porous reinforced framework of this invention can meet the requirements of long-term, highly reversible, and low-attenuation charge-discharge in vanadium redox flow batteries, possessing both excellent electrochemical and structural stability, providing a strong guarantee for its lifespan and reliability in practical large-scale energy storage applications.

[0161] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. An ion exchange membrane, characterized in that, This includes ion exchange resins and hydrophilic porous membranes; The hydrophilic porous membrane comprises a porous fiber interwoven structure formed of ultra-high molecular weight polyethylene and hydrophilic nanoparticles dispersed in the ultra-high molecular weight polyethylene, wherein at least a portion of the hydrophilic nanoparticles are exposed in the pores of the porous fiber interwoven structure; the thickness of the hydrophilic porous membrane is 100 nm to 15 μm, and the hydrophilic porous membrane is prepared by the following steps: S1, Raw material premixing: Ultra-high molecular weight polyethylene, hydrophilic nanoparticles, plasticizers and antioxidants are mixed at a preset temperature to form a premix; the weight average molecular weight of the ultra-high molecular weight polyethylene is 1 million to 15 million g / mol, the hydrophilic nanoparticles are silica nanoparticles, metal oxide nanoparticles or nanoparticles with hydrophilic functional groups formed on the surface, and the hydrophilic functional groups are at least one of hydroxyl, carboxyl, amino and sulfonic acid groups. S2, Extrusion: The premix is ​​extruded into a film using a twin-screw extruder to obtain a gel film; the twin-screw extruder includes, from the feeding direction to the extrusion direction, a preheating zone, a melt plasticizing zone, a homogenizing and metering zone, a melt pump, and a die; the melt plasticizing zone is configured with a temperature not lower than 80°C above the melting point of the ultra-high molecular weight polyethylene, and the shear rate of the premix is ​​1000~1500 s. -1 The outlet pressure of the melt pump shall not be lower than 2.5 MPa, and the pressure fluctuation shall not exceed 1%. S3, Stretching: First, the gel film is subjected to biaxial synchronous stretching at a first stretch ratio at a first preset temperature, and then the gel film is subjected to biaxial synchronous stretching at a second preset temperature at a second stretch ratio; the first preset temperature is lower than the second preset temperature, and both the first preset temperature and the second preset temperature are 20°C lower than the melting point of the gel film; the first stretch ratio is less than the second stretch ratio; the stretching rate during the stretching process is 50~100mm / min; S4, Extraction: Extracting the stretched film using an extractant; S5, Drying and Annealing: Dry the extracted film and then anneal the dried film to obtain a porous film with a porous fiber interwoven structure. The ion exchange resin covers the surface of the hydrophilic porous membrane and fills the internal pores of the hydrophilic porous membrane, so that the hydrophilic porous membrane forms a continuous through ion transport channel from one surface to the opposite surface.

2. The ion exchange membrane according to claim 1, characterized in that, An oxide layer is deposited on at least one surface of the hydrophilic porous membrane, and the oxide layer conformally covers the fiber surface of the porous fiber interwoven structure. The oxide layer is made of silicon dioxide or metal oxide.

3. The ion exchange membrane according to claim 1, characterized in that, At least one surface of the hydrophilic porous membrane is deposited with a metal layer, which conformally covers the fiber surface of the porous fiber interwoven structure. The metal layer is made of at least one of titanium, aluminum, nickel, copper, chromium, iron, platinum, and palladium.

4. The ion exchange membrane according to claim 1, characterized in that, The average pore size of the porous fiber interwoven structure is 15~500nm.

5. The ion exchange membrane according to claim 1, characterized in that, The porosity of the porous fiber interwoven structure is 30%~90%.

6. The ion exchange membrane according to claim 1, characterized in that, The temperature of the preheating zone is 150~180℃.

7. The ion exchange membrane according to claim 1, characterized in that, The temperature of the melting and plasticizing zone is 200~230℃.

8. The ion exchange membrane according to claim 1, characterized in that, The temperature of the homogenization metering zone is 240~250℃.

9. The ion exchange membrane according to claim 1, characterized in that, The first preset temperature is 90~100℃, and the second preset temperature is 120~130℃.

10. The ion exchange membrane according to claim 1, characterized in that, The first stretch ratio is 4 times, and the second stretch ratio is 8 to 12 times.

11. The ion exchange membrane according to claim 1, characterized in that, The hydrophilic nanoparticles account for 0.5 to 10% of the total weight of the premix.

12. The ion exchange membrane according to claim 1, characterized in that, The antioxidant is at least one of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and tris(2,4-di-tert-butylphenyl)phosphite.

13. The ion exchange membrane according to claim 1, characterized in that, The antioxidant accounts for 0.1 to 0.8% of the total weight of the premix.

14. The ion exchange membrane according to claim 1, characterized in that, The plasticizer is at least one of paraffin oil, naphthenic oil, dioctyl terephthalate, and methyl epoxide.

15. The ion exchange membrane according to claim 1, characterized in that, Step S5 is followed by the following steps: A metal layer is deposited on the surface of a porous membrane having a porous fiber interwoven structure, wherein the metal layer is made of at least one of titanium, aluminum, nickel, copper, chromium, iron, platinum, and palladium.

16. The ion exchange membrane according to claim 1, characterized in that, Step S5 is followed by the following steps: A precursor layer is deposited on the surface of a porous membrane having a porous fiber interwoven structure, wherein the precursor layer is made of at least one of silicon, titanium, aluminum, nickel, copper, chromium, and iron. The precursor layer is subjected to low-temperature oxidation treatment at a temperature of 70~100℃.

17. The ion exchange membrane according to claim 1, characterized in that, Prepared by the following steps: The first layer of ion exchange resin solution was coated onto the substrate; A hydrophilic porous membrane is attached to the surface of the first layer of ion exchange resin solution. After attachment, pressure is applied to the surface of the hydrophilic porous membrane to degas the air. After the degassing is completed, a second layer of ion exchange resin solution is coated onto the surface of the hydrophilic porous membrane to obtain a composite membrane structure. The composite membrane structure is then dried and cured.

18. The ion exchange membrane according to claim 1, characterized in that, The tensile strength of the hydrophilic porous membrane is 100~2000MPa.

19. An electrochemical device, characterized in that, Includes the ion exchange membrane according to any one of claims 1-18.

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