Ion exchange composite membrane, preparation and application thereof, and hydrogen production device by electrolysis of water

Abstract

The application discloses an ion exchange composite membrane, a preparation and application thereof, and a hydrogen production device for electrolyzing water, and a preparation method of the ion exchange composite membrane comprises the following steps: (1) placing a perfluorosulfonyl fluoride resin membrane, a reinforcing mesh cloth and the perfluorosulfonyl fluoride resin membrane in sequence and superimposing to obtain a superimposed membrane, and then performing hot pressing to obtain a perfluorosulfonyl fluoride composite membrane; and (2) performing hydrolysis transformation on the perfluorosulfonyl fluoride composite membrane to obtain the ion exchange composite membrane. The mesh cloth wire structure of the perfluorosulfonic acid ion exchange composite membrane prepared by the method is kept intact, the mesh cloth is uniformly distributed, the membrane body is flat and free of bubbles, the resin matrix and the reinforcing mesh cloth layer do not separate after long-time high-temperature water soaking treatment, the tensile strength is higher, the elongation at break is lower, the surface swelling rate is lower, the structure is denser, the stability is higher, and the performances are better than those of a dipping coating membrane.

Description

Technical Field

[0001] This invention relates to the field of ion exchange membranes, and more specifically, to an ion exchange composite membrane, its preparation and application, and an electrolysis water hydrogen production device. Background Technology

[0002] Perfluorosulfonic acid ion exchange membranes possess excellent chemical stability, proton conductivity, and gas separation properties, making them a core material of great interest in the field of hydrogen fuel cells. Perfluorosulfonic acid ion exchange membranes are prepared using perfluorosulfonyl fluoride resins as precursors. This involves melt-extruding a perfluorosulfonyl fluoride resin obtained by copolymerizing perfluorovinyl ethers with terminal -SO2F groups with tetrafluoroethylene, followed by hydrolysis to obtain a perfluorosulfonic acid ion exchange membrane with terminal -SO3H groups.

[0003] However, traditional homogeneous perfluorosulfonic acid ion exchange membranes suffer from poor dimensional stability, low mechanical strength, and poor performance stability. Preparing fiber-reinforced composite perfluorosulfonic acid ion exchange membranes is the mainstream method to solve these problems. The specific processes mainly fall into two categories: First, the impregnation method, where a perfluorosulfonic acid resin solution is directly immersed into the pores of the reinforcing fiber mesh, followed by heat treatment and drying to obtain a mesh-reinforced perfluorosulfonic acid composite membrane. The disadvantage of this method is that the hydrophilic perfluorosulfonic acid resin solution is difficult to completely penetrate the hydrophobic reinforcing mesh pores, and the consistency of the resin layer thickness on both sides of the mesh is also difficult to control. Second, the lamination method for preparing the composite membrane. This method makes it difficult to ensure effective bonding between the resin and the mesh, and the two may separate during subsequent hydrolysis and transformation.

[0004] Therefore, there is an urgent need to provide a method for preparing an ion exchange membrane that effectively combines resin and mesh, has good dimensional stability, and high mechanical strength. Summary of the Invention

[0005] This invention is based on the inventors' discoveries and understanding of the following facts and problems: Traditional homogeneous perfluorosulfonic acid ion exchange membranes suffer from poor dimensional stability, low mechanical strength, and poor performance stability. The preparation of fiber-reinforced composite perfluorosulfonic acid ion exchange membranes using the impregnation coating method presents challenges. The hydrophilic perfluorosulfonic acid resin solution struggles to fully penetrate the pores of the hydrophobic reinforcing mesh, and the consistency of the resin layer thickness on both sides of the mesh is difficult to control. The lamination method fails to ensure effective bonding between the resin layer and the mesh, and the resulting composite membrane is prone to delamination during hydrolysis and transformation.

[0006] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose an ion-exchange composite membrane, its preparation and application, and an electrolytic water hydrogen production device. The perfluorosulfonic acid ion-exchange composite membrane obtained maintains an intact mesh fiber structure, has a uniform mesh distribution, a smooth membrane without bubbles, and does not exhibit peeling between the resin matrix and the reinforcing mesh layer after prolonged high-temperature water immersion treatment. It also exhibits higher tensile strength, lower elongation at break, lower surface swelling rate, a denser structure, and higher stability, with all performance characteristics superior to impregnated coating membranes.

[0007] This invention provides a method for preparing an ion-exchange composite membrane, comprising the following steps:

[0008] (1) The perfluorosulfonyl fluoride resin film, the reinforcing mesh, and the perfluorosulfonyl fluoride resin film are stacked in sequence to obtain the stacked film, and then hot-pressed to obtain the perfluorosulfonyl fluoride composite film.

[0009] (2) The perfluorosulfonyl fluoride composite membrane is hydrolyzed and transformed to obtain an ion exchange composite membrane.

[0010] The advantages and technical effects of the preparation method of the ion exchange composite membrane in this invention are as follows: A perfluorosulfonyl fluoride composite membrane is prepared by hot-pressing. The perfluorosulfonyl fluoride composite membrane has an intact filament structure, a compact texture, and a smooth, uniform membrane free of bubbles. It is then hydrolyzed to obtain the ion exchange composite membrane. This method can also achieve composite membranes with three or more layers. The prepared ion exchange composite membrane meets all performance requirements well. The mesh filament structure remains intact, the mesh is evenly distributed, the membrane is smooth and free of bubbles, and after prolonged high-temperature immersion in water, no peeling occurs between the resin matrix and the reinforcing mesh layers. It exhibits higher tensile strength, lower elongation at break, lower surface swelling rate, a denser structure, and higher stability, with performance superior to impregnated coating membranes. This method is simple to prepare, highly operable, universally applicable, does not rely on specialized equipment, and is low-cost, making it suitable for the rapid preparation of perfluorosulfonic acid ion exchange composite membranes.

[0011] In some embodiments, in step (1), the reinforcing mesh includes at least one of polyetheretherketone or polyphenylene sulfide;

[0012] And / or, in step (1), the thickness of the reinforcing mesh is 20-100 μm;

[0013] And / or, in step (1), the porosity of the reinforcing mesh is 60-90%;

[0014] And / or, in step (1), the thickness of the perfluorosulfonyl fluoride resin film is not less than 20 μm;

[0015] And / or, in step (1), the hot-pressing composite is performed by clamping and hot-pressing a graphite plate.

[0016] In some embodiments, in step (1), polyimide films are respectively disposed on both sides of the stacked film, hot-pressed composite is performed, and the polyimide films are removed after cooling to obtain a perfluorosulfonyl fluoride composite film.

[0017] In some embodiments, the temperature of the hot-pressing composite is 180–250°C; and / or, the pressure of the hot-pressing composite is 0.5–4 MPa; and / or, the number of venting cycles of the hot-pressing composite is 3–10; and / or, the hot-pressing composite time is 1–20 min.

[0018] In some embodiments, in step (1), the stacked film is subjected to a first hot-pressing composite and cooled to obtain a pre-pressed composite film; then the pre-pressed composite film is subjected to a second hot-pressing composite and cooled to obtain a perfluorosulfonyl fluoride composite film.

[0019] In some embodiments, in step (1), polytetrafluoroethylene films are respectively placed on both sides of the stacked film, and a first hot-pressing composite is performed. After cooling, the polytetrafluoroethylene film is removed to obtain a pre-pressed composite film. Then, polyimide films are respectively placed on both sides of the pre-pressed composite film, and a second hot-pressing composite is performed. After cooling, the polyimide film is removed to obtain a perfluorosulfonyl fluoride composite film.

[0020] In some embodiments, the temperature of the first hot-press bonding is 180–200°C; and / or, the pressure of the first hot-press bonding is 0.5–2 MPa; and / or, the number of venting operations in the first hot-press bonding is 3–10; and / or, the time of the first hot-press bonding is 1–10 min; and / or, the temperature of the second hot-press bonding is 200–250°C; and / or, the pressure of the second hot-press bonding is 1–4 MPa; and / or, the number of venting operations in the second hot-press bonding is 3–10; and / or, the time of the second hot-press bonding is 5–20 min.

[0021] In some embodiments, in step (2), the hydrolysis transformation includes alkali treatment and acid treatment of the perfluorosulfonyl fluoride composite membrane; and / or, the temperature of the hydrolysis transformation is 65-80°C; and / or, the thickness of the ion exchange composite membrane is 90-120 μm.

[0022] And / or, repeat step (1), wherein the perfluorosulfonyl fluoride composite membrane obtained in the previous step (1) is used as at least one of the two perfluorosulfonyl fluoride resin membranes in the subsequent step (1).

[0023] This invention provides an ion exchange composite membrane, which is prepared using the method described in this invention. In this invention, the perfluorosulfonic acid ion exchange composite membrane maintains an intact mesh structure, has a uniform mesh distribution, and is smooth and bubble-free. After prolonged high-temperature immersion in water, no peeling occurs between the resin matrix and the reinforcing mesh layer. Its performance is superior to that of impregnated coating membranes.

[0024] This invention provides an application of an ion exchange composite membrane for hydrogen production via water electrolysis. This invention incorporates all the advantages of ion exchange composite membranes, which will not be elaborated further here.

[0025] This invention provides an electrolytic water hydrogen production device, including the ion exchange composite membrane described in this invention. This invention possesses all the advantages of the ion exchange composite membrane, which will not be elaborated further here. Attached Figure Description

[0026] Figure 1 This is a SEM image of the ion exchange composite membrane in Example 1. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0028] A method for preparing an ion exchange composite membrane according to an embodiment of the present invention includes the following steps:

[0029] (1) The perfluorosulfonyl fluoride resin film, the reinforcing mesh, and the perfluorosulfonyl fluoride resin film are stacked in sequence to obtain the stacked film, and then hot-pressed to obtain the perfluorosulfonyl fluoride composite film.

[0030] Specifically, the perfluorosulfonyl fluoride resin film, the reinforcing mesh, and the perfluorosulfonyl fluoride resin film are stacked sequentially along the film thickness direction; then hot pressing is performed along the film thickness direction.

[0031] (2) The perfluorosulfonyl fluoride composite membrane is hydrolyzed and transformed to obtain an ion exchange composite membrane.

[0032] The method for preparing the ion exchange composite membrane in this invention involves hot-pressing to obtain a perfluorosulfonyl fluoride composite membrane. The perfluorosulfonyl fluoride composite membrane exhibits a complete filament structure, compact texture, and a smooth, uniform membrane free of bubbles. This membrane is then hydrolyzed to obtain the ion exchange composite membrane. This method can also achieve composite membranes with three or more layers. The resulting ion exchange composite membrane meets all performance requirements well. The mesh filament structure remains intact, the mesh distribution is uniform, the membrane is smooth and bubble-free, and after prolonged high-temperature immersion in water, no delamination occurs between the resin matrix and the reinforcing mesh layers. It exhibits higher tensile strength, lower elongation at break, lower surface swelling rate, a denser structure, and higher stability, with performance superior to impregnated membranes. This method is simple, highly operable, universally applicable, does not rely on specialized equipment, and is low-cost, making it suitable for the rapid preparation of perfluorosulfonic acid ion exchange composite membranes.

[0033] In some embodiments, in step (1), the reinforcing mesh includes at least one of polyetheretherketone (PEEK) or polyphenylene sulfide (PPS), optionally, PEEK-reinforced mesh or PPS-reinforced mesh; preferably, the reinforcing mesh is woven from fibers with cross-linking between the filaments; and / or, in step (1), the thickness of the reinforcing mesh is 20–100 μm, specifically, for example, 20 μm, 40 μm, 50 μm, 60 μm, 80 μm, 100 μm; and / or, in step (1), the porosity of the reinforcing mesh is 60–90%, specifically, for example, 60%, 70%, 80%, 90%. In this embodiment of the invention, the reinforcing mesh is preferably woven from acid and alkali resistant engineering plastic fibers of polyether ether ketone and polyphenylene sulfide. The mesh structure is stable and has high strength, which is conducive to effective composite with perfluorinated resin and improves mechanical strength and stability. By optimizing the thickness and porosity of the reinforcing mesh, it is beneficial to further improve the tightness of the resin-mesh composite, prevent delamination during hydrolysis and transformation, and prevent peeling between the resin matrix and the reinforcing mesh layers after long-term high-temperature water immersion treatment.

[0034] In some embodiments, in step (1), the thickness of the perfluorosulfonyl fluoride resin membrane is not less than 20 μm, specifically, for example, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm; optionally, the two perfluorosulfonyl fluoride resin membranes in step (1) have the same thickness; preferably, the perfluorosulfonyl fluoride resin membrane is a perfluorosulfonyl fluoride homogeneous membrane; the perfluorosulfonyl fluoride homogeneous membrane is obtained by melt extrusion.

[0035] In some embodiments, in step (1), the hot pressing composite is performed using a flatbed hot press; the hot pressing composite is performed using graphite plates for clamping hot pressing composite; specifically, two graphite plates are clamped together for hot pressing composite. In this embodiment of the invention, graphite plates are used as molds. Graphite plates have excellent thermal conductivity and flatness, which is beneficial for resin softening and interlayer venting, further improving the tightness of the resin-mesh composite.

[0036] In some embodiments, in step (1), polyimide films are respectively disposed on both sides of the stacked film, and hot-pressed composite is performed. After cooling, the polyimide films are removed to obtain a perfluorosulfonyl fluoride composite film. Optionally, the process is set to adhesive bonding, utilizing the adhesiveness of the perfluorosulfonyl fluoride resin film itself. Optionally, the cooling is performed to room temperature. Optionally, the hot pressing is performed using a flatbed hot press. Two graphite plates are sandwiched together for hot pressing composite. Specifically, hot pressing is performed along the film thickness direction. In this embodiment of the invention, polyimide films are respectively disposed on both sides of the stacked film. The polyimide films are heat-resistant, ensuring that the finished composite film is uniform and flat.

[0037] In some embodiments, the hot-pressing temperature is 180–250°C, specifically, for example, 180°C, 200°C, 220°C, 230°C, 250°C; and / or, the hot-pressing pressure is 0.5–4 MPa, specifically, for example, 0.5 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa; and / or, the number of venting cycles in the hot-pressing is 3–10, specifically, for example, 3, 5, 7, 8, 10; and / or, the hot-pressing time is 1–20 min, specifically, for example, 1 min, 3 min, 4 min, 5 min, 6 min, 8 min, 10 min, 15 min, 20 min. In this embodiment of the invention, the hot-pressing temperature is preferred. When the hot-pressing temperature is too low, for example, below 180°C, the perfluorosulfonyl fluoride resin is not completely softened, the composite structure with the mesh is incomplete, and subsequent hydrolysis and transformation easily leads to interlayer separation and poor stability. By optimizing the pressure, number of venting cycles, and time of hot pressing, it is beneficial to further improve the composite strength of the resin layer and the mesh fabric.

[0038] In some embodiments, in step (1), the stacked film is subjected to a first hot-pressing composite and cooled to obtain a pre-pressed composite film; then the pre-pressed composite film is subjected to a second hot-pressing composite and cooled to obtain a perfluorosulfonyl fluoride composite film; specifically, hot pressing is performed along the film thickness direction;

[0039] Preferably, polytetrafluoroethylene (PTFE) films are respectively placed on both sides of the stacked film, and a first hot-pressing composite is performed. After cooling, the PTFE films are removed to obtain a pre-pressed composite film. Then, polyimide films are respectively placed on both sides of the pre-pressed composite film, and a second hot-pressing composite is performed. After cooling, the polyimide films are removed to obtain a perfluorosulfonyl fluoride composite film. Optionally, the process is performed by bonding, utilizing the adhesive properties of the perfluorosulfonyl fluoride resin film itself. Optionally, the hot pressing is performed using a flatbed hot press; two graphite plates are sandwiched together for hot pressing composite; the cooling is performed to room temperature.

[0040] Specifically, in step (1), a first layer of perfluorosulfonyl fluoride resin film is pasted onto a polytetrafluoroethylene film, then a reinforcing mesh is stacked on the first layer of perfluorosulfonyl fluoride resin film, a second layer of perfluorosulfonyl fluoride resin film is stacked on the reinforcing mesh, and finally a polytetrafluoroethylene film is pasted onto the second layer of perfluorosulfonyl fluoride resin film to obtain a pre-composite film; the pre-composite film is subjected to a first hot-pressing composite, and after cooling, the polytetrafluoroethylene film is removed to obtain a pre-pressed composite film; the pre-pressed composite film is laid flat and pasted between two layers of polyimide film, and a second hot-pressing composite is performed, and after cooling, the polyimide film is removed to obtain a perfluorosulfonyl fluoride composite film; optionally, the cooling is cooling to room temperature; the perfluorosulfonyl fluoride resin film is a perfluorosulfonyl fluoride homogeneous film; the hot-pressing composite is performed by sandwiching two graphite plates together.

[0041] In this embodiment of the invention, compared to performing only one hot-pressing composite, performing two hot-pressing composites is beneficial for interlayer degassing. The resulting membrane structure is intact, free of bubbles, and the resin and mesh are tightly bonded, preventing interlayer separation. This is beneficial for further improving stability, mechanical strength, conductivity, and water electrolysis performance. Polytetrafluoroethylene (PTFE) membranes are first placed on both sides of the stacked membrane. The PTFE membrane is soft, which facilitates interlayer degassing. Then, a polyimide membrane is placed. The polyimide membrane is rigid, ensuring the finished composite membrane is flat and wrinkle-free. Preferably, the first hot-pressing composite is performed with PTFE membranes on both sides, followed by the second hot-pressing composite with polyimide membranes on both sides. Compared to using PTFE membranes in both hot-pressing composites, or using polyimide membranes in both hot-pressing composites, or placing the polyimide membrane first and then the PTFE membrane in both hot-pressing composites, this method separates the degassing and composite steps, ensuring no bubble residue remains in the composite membrane after hot pressing, and maintaining an intact interlayer structure without separation.

[0042] In some embodiments, the temperature of the first hot-pressing composite is 180–200°C, specifically, for example, 180°C, 190°C, 195°C, 200°C; and / or, the pressure of the first hot-pressing composite is 0.5–2 MPa, specifically, for example, 0.5 MPa, 1 MPa, 1.5 MPa, 1.9 MPa, 2 MPa; and / or, the number of venting cycles of the first hot-pressing composite is 3–10, specifically, for example, 3, 4, 5, 7, 8, 10; and / or, the time of the first hot-pressing composite is 1–10 min, specifically, for example, 1 min, 3 min, 4 min, 5 min, 6 min, 8 min, 10 min, optionally 1–5 min;

[0043] And / or, the temperature of the second hot-pressing composite is 200-250°C, specifically, for example, 200°C, 220°C, 230°C, 250°C; and / or, the pressure of the second hot-pressing composite is 1-4 MPa, specifically, for example, 1 MPa, 2 MPa, 2.1 MPa, 3 MPa, 4 MPa; and / or, the number of venting operations in the second hot-pressing composite is 3-10 times, specifically, for example, 3 times, 5 times, 7 times, 8 times, 10 times; and / or, the time of the second hot-pressing composite is 5-20 min, specifically, for example, 5 min, 6 min, 8 min, 10 min, 15 min, 20 min;

[0044] And / or, the temperature of the second hot-press bonding is higher than the temperature of the first hot-press bonding; the pressure of the second hot-press bonding is higher than the pressure of the first hot-press bonding; and the time of the second hot-press bonding is longer than the time of the first hot-press bonding.

[0045] In this embodiment of the invention, compared to performing hot-pressing composite only once, performing hot-pressing twice, and performing hot-pressing in steps, is beneficial for interlayer air release, improving stability, mechanical strength, electrical conductivity and water electrolysis performance. The first pre-pressing in the two hot-pressing processes is carried out under relatively mild conditions and with lower pressure, which is beneficial for the release of air trapped between the perfluorosulfonyl fluoride resin membranes. The second hot-pressing is carried out under high temperature, high pressure and long duration, which enables the resin to be completely composited with the mesh.

[0046] In some embodiments, step (1) is repeated, wherein the perfluorosulfonyl fluoride composite membrane obtained in the previous step (1) is used as at least one of the two perfluorosulfonyl fluoride resin membranes in the subsequent step (1), that is, the perfluorosulfonyl fluoride composite membrane obtained in step (1) is used as at least one of the two perfluorosulfonyl fluoride resin membranes in the next step (1), that is, at least one of the two perfluorosulfonyl fluoride resin membranes is the previous perfluorosulfonyl fluoride composite membrane, and step (1) is repeated to prepare a multilayer composite ion exchange membrane; optionally, step (1) is repeated 1-3 times, specifically, for example, once, twice, three times; after repeating step (1), step (2) is performed to prepare a multilayer composite ion exchange membrane. In the embodiments of the present invention, the preparation of ion exchange composite membranes with three or more layers can be realized.

[0047] In some embodiments, in step (2), the hydrolysis transformation includes sequentially subjecting the perfluorosulfonyl fluoride composite membrane to alkali treatment and acid treatment; and / or, the temperature of the hydrolysis transformation is 65-80°C, specifically, for example, 65°C, 70°C, 75°C, 80°C; the temperature of the alkali treatment is 65-80°C, specifically, for example, 65°C, 70°C, 75°C, 80°C; the temperature of the acid treatment is 65-80°C, specifically, for example, 65°C, 70°C, 75°C, 80°C;

[0048] Preferably, the alkaline treatment involves immersing the perfluorosulfonyl fluoride composite membrane in an alkaline solution; the acid treatment involves immersing the alkaline-treated composite membrane in an acid solution; optionally, the alkaline solution includes a potassium hydroxide solution; the acid includes a sulfuric acid solution; the concentration of the alkaline solution is 7-8%; the concentration of the acid is 5-7%; the immersion time in the alkaline solution is 2-3 hours; and the immersion time in the acid solution is 0.5-1 hour. In this embodiment of the invention, the perfluorosulfonyl fluoride composite membrane is sequentially immersed in an alkaline solution and an acid solution to convert the sulfonyl fluoride groups into sulfonic acid groups with ion exchange capacity.

[0049] In some embodiments, in step (2), the thickness of the ion exchange composite membrane is 90 to 120 μm, specifically, for example, 90 μm, 100 μm, 110 μm, 120 μm.

[0050] This invention discloses an ion exchange composite membrane, which is prepared using the method described in this invention. In this embodiment, the perfluorosulfonic acid ion exchange composite membrane exhibits an intact mesh structure, uniform mesh distribution, a smooth membrane free of bubbles, and no peeling between the resin matrix and the reinforcing mesh layer after prolonged high-temperature water immersion treatment. Its performance is superior to that of resin-coated membranes.

[0051] In some embodiments, the tensile strength of the ion exchange composite membrane is not less than 37 MPa, the elongation at break is not more than 30%, and the surface swelling ratio is not more than 3%.

[0052] This invention discloses an application of an ion exchange composite membrane used for hydrogen production via water electrolysis. This embodiment of the invention possesses all the advantages of an ion exchange composite membrane, which will not be elaborated further here.

[0053] An electrolytic water hydrogen production device according to an embodiment of the present invention includes the ion exchange composite membrane described in the embodiment of the present invention. The present invention possesses all the advantages of the ion exchange composite membrane, which will not be elaborated further here.

[0054] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0055] Example 1

[0056] A method for preparing an ion exchange composite membrane includes the following steps:

[0057] (1) A 100mm×200mm, 30μm thick perfluorosulfonyl fluoride homogeneous membrane is flatly pasted onto a PTFE membrane. The air trapped between the membranes is expelled by a scraper. Then, a 50μm thick polyetheretherketone mesh (70% porosity) is laid flat on the perfluorosulfonyl fluoride homogeneous membrane. Finally, another perfluorosulfonyl fluoride homogeneous membrane of the same size pasted on the PTFE membrane is neatly stacked on top to obtain a pre-composite membrane. The polyetheretherketone mesh is woven from polyetheretherketone fibers, and the fibers have been cured and cross-linked. The material of the perfluorosulfonyl fluoride homogeneous membrane is perfluorosulfonyl fluoride resin, which is obtained by melt extrusion.

[0058] (2) The pre-composite membrane is sandwiched between two graphite plates and placed on the hot press plate. The first hot press is carried out under the preset parameters: temperature 200℃, pressure 1.5MPa, exhaust 4 times, time 300s. After the hot press is completed and cooled to room temperature, the graphite plates are removed and the PTFE membrane is peeled off to obtain the pre-composite membrane.

[0059] (3) The pre-pressed composite film is flatly pasted between two layers of polyimide film. Two flat graphite plates are used to clamp the film. The second hot-pressing composite is carried out under the preset parameters: temperature 220℃, pressure 3MPa, exhaust 4 times, time 600s, cool to room temperature, peel off the polyimide film, and obtain perfluorosulfonyl fluoride composite film.

[0060] (4) The perfluorosulfonyl fluoride composite membrane prepared by hot pressing is subjected to hydrolysis transformation: it is soaked in 7% potassium hydroxide solution at 80°C for 2 hours, soaked in 5% sulfuric acid solution at 65°C for 1 hour, and dried to obtain an ion exchange composite membrane with a thickness of 100 μm.

[0061] Example 2

[0062] A method for preparing an ion exchange composite membrane includes the following steps:

[0063] (1) A 100mm×200mm, 35μm thick perfluorosulfonyl fluoride homogeneous membrane is flatly pasted onto a PTFE membrane. The air trapped between the membranes is expelled by a scraper. Then, a 60μm polyphenylene sulfide mesh (porosity 80%) is laid flat on the perfluorosulfonyl fluoride homogeneous membrane. Finally, another perfluorosulfonyl fluoride homogeneous membrane of the same size pasted on the PTFE membrane is neatly stacked on top to obtain a pre-composite membrane. The polyphenylene sulfide mesh is woven from polyphenylene sulfide fibers, and the fibers have been cured and cross-linked. The material of the perfluorosulfonyl fluoride homogeneous membrane is perfluorosulfonyl fluoride resin, which is obtained by melt extrusion.

[0064] (2) The pre-composite membrane is sandwiched between two graphite plates and placed on the hot press plate. The first hot press is carried out under the preset parameters: temperature 190℃, pressure 1.5MPa, exhaust 5 times, time 200s. After the hot press is completed and cooled to room temperature, the graphite plates are removed and the PTFE membrane is peeled off to obtain the pre-composite membrane.

[0065] (3) The pre-pressed composite film is flatly pasted between two layers of polyimide film. Two flat graphite plates are used to clamp the film. The second hot-pressing composite is carried out under the preset parameters: temperature 250℃, pressure 4MPa, exhaust 5 times, time 600s, cool to room temperature, peel off the polyimide film, and obtain perfluorosulfonyl fluoride composite film.

[0066] (4) The perfluorosulfonyl fluoride composite membrane prepared by hot pressing is subjected to hydrolysis transformation: it is soaked in 7% potassium hydroxide solution at 80°C for 2 hours, soaked in 5% sulfuric acid solution at 65°C for 1 hour, and dried to obtain an ion exchange composite membrane with a thickness of 115 μm.

[0067] Example 3

[0068] A method for preparing an ion exchange composite membrane includes the following steps:

[0069] (1) A 100mm×200mm perfluorosulfonyl fluoride homogeneous membrane with a thickness of 30μm is flatly pasted onto the polyimide membrane. The air trapped between the membranes is expelled by a scraper. Then, a 50μm polyether ether ketone mesh (porosity of 70%) is laid flat on the homogeneous membrane. Finally, another perfluorosulfonyl fluoride homogeneous membrane of the same size pasted on the polyimide membrane is neatly stacked on top to obtain a pre-composite membrane.

[0070] (2) The pre-composite film is sandwiched between two graphite plates and placed on the hot press plate. Hot pressing is performed under preset parameters: temperature 220℃, pressure 3MPa, exhaust 7 times, time 600s. After the hot pressing is completed and cooled to room temperature, the graphite plates are removed and the polyimide film is peeled off to obtain the perfluorosulfonyl fluoride composite film.

[0071] (3) The perfluorosulfonyl fluoride composite membrane prepared by hot pressing is subjected to hydrolysis transformation: it is soaked in 7% potassium hydroxide solution at 80℃ for 2h, soaked in 5% sulfuric acid solution at 65℃ for 1h, and dried to obtain an ion exchange composite membrane with a thickness of 105μm.

[0072] Example 4

[0073] The method for preparing ion exchange composite membranes, used to prepare large-size membrane materials, includes the following steps:

[0074] (1) A 500mm×750mm perfluorosulfonyl fluoride homogeneous membrane with a thickness of 30μm is flatly pasted onto the PTFE membrane. The air trapped between the membranes is expelled by a scraper. Then, a 50μm polyether ether ketone mesh (porosity of 70%) is laid flat on the homogeneous membrane. Finally, another perfluorosulfonyl fluoride homogeneous membrane of the same size pasted on the PTFE membrane is neatly stacked on top to obtain a pre-composite membrane.

[0075] (2) The pre-composite film is sandwiched between two graphite plates and placed on the hot press plate. Hot pressing is performed under preset parameters: temperature 200℃, pressure 1.5MPa, exhaust 4 times, time 300s. After the hot pressing is completed and cooled to room temperature, the graphite plates are removed and the PTFE film is peeled off to obtain the pre-composite film.

[0076] (3) The pre-pressed composite film is flatly pasted between two layers of polyimide film. Two flat graphite plates are used to clamp the film. The second hot-pressing composite is carried out under the preset parameters: temperature 250℃, pressure 3MPa, exhaust 8 times, time 1200s, cool to room temperature, peel off the polyimide film, and obtain perfluorosulfonyl fluoride composite film.

[0077] (4) The perfluorosulfonyl fluoride composite membrane prepared by hot pressing is subjected to hydrolysis transformation: it is soaked in 7% potassium hydroxide solution at 80°C for 3 hours, then soaked in 7% sulfuric acid solution at 70°C for 1 hour, and dried to obtain an ion exchange composite membrane with a thickness of 103 μm.

[0078] Example 5

[0079] A method for preparing an ion exchange composite membrane includes the following steps:

[0080] (1) A 100mm×200mm, 30μm thick perfluorosulfonyl fluoride homogeneous membrane is flatly pasted onto a polyimide membrane. The air trapped between the membranes is expelled by a scraper. Then, a 50μm polyetheretherketone mesh (70% porosity) is laid flat on the perfluorosulfonyl fluoride homogeneous membrane. Finally, another perfluorosulfonyl fluoride homogeneous membrane of the same size is neatly stacked on top of the polyimide membrane to obtain a pre-composite membrane. The polyetheretherketone mesh is woven from polyetheretherketone fibers and the fibers have been cured and cross-linked. The material of the perfluorosulfonyl fluoride homogeneous membrane is perfluorosulfonyl fluoride resin, which is obtained by melt extrusion.

[0081] (2) The pre-composite film is sandwiched between two graphite plates and placed on the hot press plate. The first hot press is carried out under the preset parameters: temperature 200℃, pressure 1.5MPa, exhaust 4 times, time 300s. After the hot press is completed and cooled to room temperature, the graphite plates are removed and the polyimide film is torn off to obtain the pre-composite film.

[0082] (3) The pre-pressed composite membrane is flatly pasted between the two PTFE membranes. Two flat graphite plates are used to clamp the membrane. The second hot-pressing composite is carried out under the preset parameters: temperature 220℃, pressure 3MPa, exhaust 4 times, time 600s, cool to room temperature, peel off the PTFE membrane, and obtain perfluorosulfonyl fluoride composite membrane.

[0083] (4) The perfluorosulfonyl fluoride composite membrane prepared by hot pressing is subjected to hydrolysis transformation: it is soaked in 7% potassium hydroxide solution at 80°C for 2 hours, soaked in 5% sulfuric acid solution at 65°C for 1 hour, and dried to obtain an ion exchange composite membrane with a thickness of 102 μm.

[0084] Comparative Example 1

[0085] A three-layer mesh-reinforced perfluorosulfonic acid ion exchange composite membrane of the same thickness as in Example 1 was prepared by a blade coating method, comprising the following steps:

[0086] (1) Weigh 22g of hydrogen-form perfluorosulfonic acid resin, dissolve it in a mixed solvent consisting of 52g of n-propanol and 26g of water to prepare a resin slurry solution with a solid content of 22wt%, and centrifuge to remove bubbles.

[0087] (2) One coat: Apply the resin slurry to a flat substrate with a wet thickness of 370 μm and dry at 80°C for 10 min.

[0088] (3) Second coating: Using the first coating as a base, apply a wet film with a thickness of 250 μm. Then, cover the second coating slurry with a 50 μm polyether ether ketone mesh (porosity of 70%). After the mesh is wetted, dry at 80°C for 10 min.

[0089] (4) Three coatings: the second coating is used as the substrate. A wet film with a thickness of 350 μm is coated, dried at 80°C for 15 min, and finally dried at 160°C for 20 min to obtain an ion exchange composite membrane with a thickness of 102 μm.

[0090] Performance tests were conducted on the ion exchange composite membranes of the examples and comparative examples:

[0091] 1. Transmission conductivity: Cut the composite membrane sample to be tested using a 30mm×10mm cutter, measure the membrane thickness and record it as d; cut several gas diffusion layers using an 18mm×5mm cutter for later use; stack the gas diffusion layers, the composite membrane sample to be tested, and the gas diffusion layers in a sandwich shape in the transmission conductivity test fixture, and place the fixture in the environmental chamber of the membrane material testing system; set the test temperature / humidity to 80℃ / 95%RH, use the membrane material testing system (MTS), measure the transmission internal resistance of the membrane sample by electrochemical impedance spectroscopy and record it as R, the effective test area of ​​the membrane is A, and calculate the transmission conductivity according to the formula d / (R*A).

[0092] 2. Electrolysis performance: The composite membrane is fabricated into a membrane electrode with an active area of ​​25 cm². 2 The cathode platinum loading is 0.1 mg / cm³. 2 The iridium loading at the anodized oxide level is 0.3 mg / cm³. 2 Then, they were assembled into a single-cell electrolyzer, and the water electrolysis performance of the composite membrane was tested under the operating temperature of 80℃.

[0093] Table 1

[0094]

[0095] As can be seen from Table 1, compared with the ion exchange composite membrane prepared by the coating method in Comparative Example 1, the ion exchange composite membrane prepared by the hot pressing method in this example has higher tensile strength, lower elongation at break, and lower surface swelling rate. This is because the hot pressing composite membrane is shaped under high temperature and high pressure, resulting in a denser structure, higher strength, and better stability.

[0096] Electrolysis tests showed that the ion exchange composite membrane prepared by the hot-pressing method in Example 1 had a lower hydrogen content in the oxygen on the anode side and relatively less gas permeation, which also indicated that the hot-pressed composite membrane structure was more compact.

[0097] Compared to Example 3, the ion exchange composite membrane of Example 1 is bubble-free, has higher tensile strength and penetration conductivity, and lower electrolytic cell voltage. This indicates that the composite effect of two hot-pressing is better than that of one hot-pressing. This is because the first preheating press of the two hot presses is carried out under milder conditions and lower pressure, which is conducive to the expulsion of air trapped between the perfluorosulfonyl fluoride homogeneous membranes. The second hot press is carried out under higher temperature, pressure and longer duration, which enables the resin to be completely composited with the mesh.

[0098] Comparing Examples 1 and 5, it can be seen that the order in which the PTFE membrane and polyimide membrane are used affects the performance of the composite membrane. The ion exchange composite membrane obtained by hot pressing with the PTFE membrane first and then the polyimide membrane has higher penetration conductivity and lower electrolytic cell voltage. This is because the PTFE membrane is soft, which facilitates interlayer degassing. The polyimide membrane, with its high rigidity, ensures the finished composite membrane is flat and wrinkle-free. By first hot-pressing the PTFE membranes on both sides and then hot-pressing the polyimide membrane a second time, the degassing and lamination steps are separated, ensuring no air bubbles remain in the composite membrane after hot pressing, maintaining an intact interlayer structure, and preventing separation even after prolonged immersion in water.

[0099] Figure 1 This is a SEM image of the ion exchange composite membrane from Example 1. Figure 1 It can be seen that the mesh-reinforced perfluorosulfonic acid ion exchange composite membrane prepared by hot pressing has a complete structure and uniform mesh distribution. The micro-thickness test results are close to the thickness gauge test results, which confirms the successful preparation of the ion exchange composite membrane.

[0100] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0101] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A method for preparing an ion-exchange composite membrane, characterized in that, Includes the following steps: (1) A perfluorosulfonyl fluoride resin film, a reinforcing mesh, and a perfluorosulfonyl fluoride resin film are stacked sequentially to obtain a stacked film. The stacked film is then subjected to a first hot-pressing composite and cooled to obtain a pre-pressed composite film. The pre-pressed composite film is then subjected to a second hot-pressing composite and cooled to obtain a perfluorosulfonyl fluoride composite film. The hot-pressing composite is performed using a flatbed hot press. The temperature of the first hot-pressing composite is 180~200℃. The pressure of the first hot-pressing composite is 0.5~2MPa. The number of venting cycles for the first hot-pressing composite is 3~10. The time for the first hot-pressing composite is 1~10min. The temperature of the second hot-pressing composite is 200~250℃. The pressure of the second hot-pressing composite is 1~4MPa. The number of venting cycles for the second hot-pressing composite is 3~10. The time for the second hot-pressing composite is 5~20min. (2) The perfluorosulfonyl fluoride composite membrane is hydrolyzed and transformed to obtain an ion exchange composite membrane.

2. The method for preparing the ion exchange composite membrane according to claim 1, characterized in that, In step (1), the reinforcing mesh includes at least one of polyetheretherketone or polyphenylene sulfide; And / or, in step (1), the thickness of the reinforcing mesh is 20~100µm; And / or, in step (1), the porosity of the reinforcing mesh is 60-90%; And / or, in step (1), the thickness of the perfluorosulfonyl fluoride resin film is not less than 20µm; And / or, in step (1), the hot-pressing composite is performed by clamping and hot-pressing a graphite plate.

3. The method for preparing the ion exchange composite membrane according to claim 1, characterized in that, Polytetrafluoroethylene (PTFE) films are placed on both sides of the stacked film, and a first hot-pressing composite is performed. After cooling, the PTFE films are removed to obtain a pre-pressed composite film. Then, polyimide films are placed on both sides of the pre-pressed composite film, and a second hot-pressing composite is performed. After cooling, the polyimide films are removed to obtain a perfluorosulfonyl fluoride composite film.

4. The method for preparing the ion exchange composite membrane according to claim 1, characterized in that, In step (2), the hydrolysis transformation includes subjecting the perfluorosulfonyl fluoride composite membrane to alkali treatment and acid treatment in sequence; And / or, the temperature of the hydrolysis transformation is 65~80℃; And / or, the thickness of the ion exchange composite membrane is 90~120µm; And / or, repeat step (1) 1-3 times, wherein the perfluorosulfonyl fluoride composite membrane obtained in the previous step (1) is used as at least one of the two perfluorosulfonyl fluoride resin membranes in the subsequent step (1).

5. An ion exchange composite membrane, characterized in that, The ion exchange composite membrane is prepared by any one of claims 1-4.

6. An application of the ion exchange composite membrane according to claim 5, characterized in that, The ion exchange composite membrane is used for hydrogen production by water electrolysis.

7. A device for producing hydrogen by electrolysis of water, characterized in that, Includes the ion exchange composite membrane as described in claim 5.

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