Bipolar membrane and preparation method thereof

Abstract

The present application discloses a bipolar membrane and a method for preparing the same. The bipolar membrane comprises: a first membrane layer comprising an anion exchange resin matrix, the surface of the first membrane layer comprising a plurality of protrusions; a second membrane layer comprising a cation exchange resin matrix, the surface of the second membrane layer comprising a plurality of recesses, wherein the first membrane layer and the second membrane layer are stacked, the protrusions and recesses interlock with each other, and the interface between the second membrane layer and the first membrane layer comprises chemical bonding; and a nanoscale solid-phase catalyst contained between the first membrane layer and the second membrane layer. The bipolar membrane of the present application comprises an anion exchange membrane and a cation exchange membrane, the two being tightly connected to effectively and stably achieve a water dissociation voltage. Furthermore, during the water dissociation and ionization process, the bipolar membrane has an extremely low degradation rate, allowing for stable and repeated use.

Description

Technical Field

[0001] The present application belongs to the technical field of membrane synthesis and preparation, and specifically relates to a bipolar membrane and a preparation method thereof. Background Art

[0002] A bipolar membrane is an ion exchange membrane, typically composed of a tightly bound anion exchange layer and a cation exchange layer. It is primarily used in electrodialysis processes. Under the influence of an external electric field, water molecules dissociate into hydrogen ions and hydroxide ions at the interface between the anion exchange layer and the cation exchange layer.

[0003] In related technologies, bipolar membranes generally have two major problems. First, the middle layer has poor ability to catalyze the water dissociation reaction under the action of large current, resulting in high transmembrane voltage and large energy consumption. Second, the anion membrane layer and the cation membrane layer fall off under the action of large current, leading to spontaneous separation, which greatly affects the service life of the bipolar membrane. Summary of the Invention

[0004] In view of this, the present application provides a bipolar membrane and a preparation method thereof, aiming to provide a bipolar membrane that can effectively reduce the water dissociation voltage under high current conditions and has a long service life.

[0005] In a first aspect, an embodiment of the present application provides a bipolar membrane, comprising:

[0006] The first membrane layer comprises an anion exchange resin matrix, and the surface of the first membrane layer comprises a plurality of protrusions.

[0007] a second membrane layer comprising a cation exchange resin matrix, wherein a surface of the second membrane layer comprises a plurality of recesses, wherein the first membrane layer and the second membrane layer are stacked, the protrusions and the recesses interlock with each other, and the interface between the second membrane layer and the first membrane layer comprises chemical bonding; and

[0008] A nano-scale solid-phase catalyst is contained between the first membrane layer and the second membrane layer.

[0009] According to an embodiment of one aspect of the present application, the surface of the second film layer includes an array of convex portions; the surface of the second film layer includes an array of concave portions, and the convex array and the concave array are embedded in each other.

[0010] According to an embodiment of one aspect of the present application, the loading amount of the nano-scale solid phase catalyst in the thickness direction of the bipolar membrane is 0.01-1 mg cm -2 , optional 0.06-0.08mg cm -2 .

[0011] According to an embodiment of one aspect of the present application, the nanoscale solid-phase catalyst is selected from metal oxides, polymers or a combination thereof.

[0012] According to an embodiment of one aspect of the present application, the volume particle size Dv50 of the nanoscale solid phase catalyst is 5-100 nm; optionally 15-25 nm; optionally 20 nm.

[0013] According to an embodiment of one aspect of the present application, the metal oxide is selected from tin dioxide, iridium dioxide, nickel oxide, iron hydroxide, graphene oxide, or a combination thereof.

[0014] According to an embodiment of one aspect of the present application, the polymer is selected from polyethylene glycol, polyvinyl alcohol, polyvinyl pyridine or a combination thereof.

[0015] According to an embodiment of one aspect of the present application, the nano-scale solid-phase catalyst is close to the first membrane layer.

[0016] In a second aspect, the present application provides a method for preparing a bipolar membrane, comprising:

[0017] providing a first solution and a second solution having reactive double bonds for forming a first film layer and a second film layer, respectively;

[0018] placing the first solution in contact with the mold to form a plurality of protrusions, and forming a first film layer by drying;

[0019] preparing a first membrane layer having a nano-scale solid-phase catalyst dispersed on the surface;

[0020] contacting a second solution with the first membrane layer having a nanoscale solid-phase catalyst dispersed on its surface to form a plurality of recesses, and drying the solution to form the second membrane layer; wherein one of the first solution and the second solution is a cation exchange resin solution and the other is an anion exchange resin solution;

[0021] Under the action of ultraviolet light, the reactive double bonds of the first membrane layer and the second membrane layer react to chemically bond the bonding interface between the second membrane layer and the first membrane layer, thereby obtaining the bipolar membrane of the first aspect, wherein a nanoscale solid-phase catalyst is accommodated between the first membrane layer and the second membrane layer.

[0022] According to an embodiment of one aspect of the present application, the anion exchange resin solution includes 3%-17% of anion exchange resin by mass.

[0023] According to an embodiment of one aspect of the present application, the raw materials of the anion exchange resin include one or more of alkyl quaternary ammonium salts, aryl quaternary ammonium salts, quaternary phosphonium salts, and coordinated metal salts.

[0024] According to an embodiment of one aspect of the present application, the anion exchange resin solution includes an organic solvent, and the organic solvent is selected from dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone, or a combination thereof.

[0025] According to an embodiment of one aspect of the present application, after the anion exchange resin solution is brought into contact with the mold, the method further includes: removing the mold on the surface of the membrane layer; optionally, the mold is a metal mold; optionally, removing the mold on the surface of the membrane layer by etching liquid.

[0026] Compared with the prior art, this application has at least the following beneficial effects:

[0027] The bipolar membrane provided by the present application has a first membrane layer surface including several convex parts, and a second membrane layer surface including several concave parts. The concave parts and the convex parts swell during use, thereby realizing the interlocking of the two membrane layers, ensuring the stability of the two membrane layers and preventing them from separating easily. The first membrane layer and the second membrane layer have a three-dimensional cross-linked structure with chemical cross-linking, which on the one hand maintains the temperature of the two membrane layers and prevents them from separating easily. On the other hand, it can enhance the specific surface area during use, increase the reaction space or reaction sites, and improve the efficiency of the action. The nanoscale solid-phase catalyst between the first membrane layer and the second membrane layer is accommodated in the concave-convex structure and the three-dimensional cross-linked structure, can exist stably and be used, and reduces or avoids its easy movement and leakage during use. The bipolar membrane of the present application comprises an anion exchange membrane and a cation exchange membrane, which are tightly connected, can effectively and stably realize the water dissociation voltage, and in the process of water dissociation and ionization, the degradation rate of the bipolar membrane is extremely low, and can be used stably and repeatedly. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0029] Figure 1 A schematic flow chart of a method for preparing a bipolar membrane according to an embodiment of the present application is shown;

[0030] Figure 2 An electron microscope image of the template substrate morphology according to an embodiment of the present application is shown;

[0031] Figure 3 An electron microscope image of the surface of one side of the anion resin matrix of an embodiment of the present application is shown;

[0032] Figure 4 An electron microscope image of a cross section of an anion resin matrix according to an embodiment of the present application is shown;

[0033] Figure 5 The element distribution of the bipolar membrane cross section of the embodiment of the present application is shown;

[0034] Figure 6 The bipolar membrane water dissociation current-voltage curve of the embodiment of the present application is shown;

[0035] Figure 7 The 100mA cm-2 bipolar membrane cross section of the embodiment of the present application is shown. -2 Water dissociation stability curve under current density. DETAILED DESCRIPTION

[0036] In order to make the application purpose, technical solution and beneficial technical effects of this application clearer, the application is further described in detail below with reference to the embodiments. It should be understood that the embodiments described in this specification are only for explaining this application and are not intended to limit this application.

[0037] For simplicity, this application only explicitly discloses certain numerical ranges. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value may serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0038] In the description of this application, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number, and “a variety” in “one or more” means two or more.

[0039] The above disclosure of the present application is not intended to describe every disclosed embodiment or every implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided through a series of examples, which can be used in various combinations. In each example, the enumeration is intended only as a representative group and should not be construed as exhaustive.

[0040] A bipolar membrane is an ion exchange membrane that, under the influence of an external electric field, dissociates water molecules into hydrogen and hydroxide ions. Bipolar membranes are primarily used in electrodialysis processes to convert salts into their corresponding acids and bases.

[0041] In related technologies, bipolar membranes have low reaction rates and high energy consumption. Compared to traditional bipolar membrane electrodialysis processes, some new application scenarios face the challenges of high currents and harsh acidic, alkaline, and oxidative environments. This leads to two major issues with bipolar membrane materials used in related technologies: First, the intermediate layer's ability to catalyze water dissociation reactions (under high currents) is poor, resulting in high transmembrane voltages and high energy consumption. Second, under high currents, the anion and cation layers can detach, leading to spontaneous separation and significantly impacting the lifespan of the bipolar membrane.

[0042] In addition, with the rapid development of water electrolysis hydrogen production technology, fuel cell technology, and carbon dioxide reduction technology, a bipolar membrane with higher reaction energy efficiency and selectivity is needed.

[0043] Research has found that the two electrochemical half reactions at the cathode and anode in the bipolar membrane cannot achieve optimal energy efficiency and selectivity under the same acid-base environment (pH value).

[0044] After research, the present application provides a bipolar membrane with several convex and concave portions. The convex and concave portions provide sufficient water dissociation reaction sites for the bipolar membrane water dissociation process, thereby avoiding high transmembrane voltage during water dissociation under high current, reducing the water dissociation voltage, maintaining a stable interface structure between the anion exchange layer and the cation exchange layer, avoiding spontaneous separation, and extending the service life of the bipolar membrane. The bipolar membrane of the present application can use asymmetric pH electrolytes at the cathode and anode to achieve electrochemical reactions, thereby improving the overall reaction energy efficiency and selectivity.

[0045] The technical solution of the present application adopts a dual physical and chemical structure. At the interface where the anion matrix and the cationic matrix meet, on the one hand, the convex and concave parts are interlocked with each other. On the other hand, the two layers of interface are tightly connected through chemical bonding, and the interface is connected, which further improves the stability of the intermediate layer, thereby improving the overall reaction efficiency and stability of the bipolar membrane.

[0046] Bipolar membrane

[0047] In a first aspect, an embodiment of the present application provides a bipolar membrane, comprising:

[0048] The first membrane layer comprises an anion exchange resin matrix, and the surface of the first membrane layer comprises a plurality of protrusions.

[0049] a second membrane layer comprising a cation exchange resin matrix, wherein a surface of the second membrane layer comprises a plurality of recesses, wherein the first membrane layer and the second membrane layer are stacked, the protrusions and the recesses interlock with each other, and the interface between the second membrane layer and the first membrane layer comprises chemical bonding; and

[0050] A nano-scale solid-phase catalyst is contained between the first membrane layer and the second membrane layer.

[0051] According to an embodiment of the present application, the anion exchange resin matrix can be a polymer with positively charged groups, which can be an alkyl quaternary ammonium salt. The main chain structure of the anion exchange resin matrix can contain an ether group, or can be a main chain without an ether group. The anion exchange resin matrix can be an ether-free biphenyl structure, a polyphenylene ether structure, a polyethersulfone structure, a polyetheretherketone structure, and an ion exchange polymer with a side chain structure of an alkyl quaternary ammonium salt structure, a piperidinium salt structure, an imidazole, or a quaternary phosphonium salt structure. For reasons of chemical stability, an ion exchange polymer with a main chain structure of an ether-free biphenyl structure and a side chain structure of a piperidinium salt is preferred.

[0052] According to an embodiment of the present application, the anion exchange resin matrix can be an anion exchange resin matrix, and its preparation method can be to synthesize a polymer main chain with a piperidine structure by superacid catalyzed polymerization reaction, and then perform side chain grafting through 1,6-diiodohexane and 1,1-dimethylbenzylamine.

[0053] According to an embodiment of the present application, the cation exchange resin matrix comprises a polymer having high ion conductivity, including any one or more of a perfluorosulfonic acid polymer, a sulfonated polyethersulfone, or a polyetheretherketone. The polymer may be a styrene compound or a perfluorosulfonic acid polymer. Alternatively, the polymer may be PSSA. The preparation method of the PSSA includes obtaining a copolymer of styrene p-sulfonate and acrylonitrile by free radical polymerization.

[0054] According to the embodiments of the present application, the interlocking of the convex and concave parts effectively prevents the middle layer of the existing bipolar membrane from cracking, thereby effectively solving the problem of catalyst loss on the middle layer and providing a guarantee for the long-term and high-current use of the bipolar membrane. At the same time, the structure formed by chemical bonding, the convex and concave parts provide more reaction catalytic sites for the bipolar membrane, enhance the specific surface area between the bipolar membranes, significantly reduce the water dissociation voltage of the bipolar membrane, improve the stability of the bipolar membrane, and enable the prepared bipolar membrane to be used at 100mA cm -2 The bipolar membrane of this application can run stably for more than 300 hours at a current density of 1Acm -2 The current density and the corresponding transmembrane voltage are between 1.13-1.38V, which is significantly better than those of related bipolar membranes.

[0055] According to the embodiment of the present application, the chemical bonding can be shown as the following structure:

[0056]

[0057] In some embodiments, the surface of the second film layer includes an array of protrusions; the surface of the second film layer includes an array of recesses, and the protrusion array and the recess array are interlocked. This can further prevent the first film layer and the second film layer from separating, thereby increasing the service life.

[0058] In some embodiments, the loading amount of the nano-scale solid phase catalyst in the thickness direction of the bipolar membrane is 0.01-1 mg / cm -2 , optional 0.06-0.08mg cm -2 By controlling the nano-scale solid-phase catalyst, the catalytic efficiency can be effectively controlled, and at the same time, the water dissociation voltage of the bipolar membrane can be controlled, which is beneficial to improving the catalytic efficiency while extending the service life of the bipolar membrane.

[0059] In some embodiments, the nanoscale solid phase catalyst is selected from metal oxides, polymers, or combinations thereof.

[0060] In some embodiments, the volume particle size of the nanoscale solid-phase catalyst is 5-100 nm, optionally 15-25 nm, or optionally 20 nm. Controlling the volume particle size of the nanoscale solid-phase catalyst can increase the specific surface area of ​​the catalytic reaction and accelerate interfacial dynamics.

[0061] In some embodiments, the metal oxide is selected from tin dioxide, iridium dioxide, nickel oxide, iron hydroxide, graphene oxide, or a combination thereof.

[0062] In some embodiments, the polymer is selected from polyethylene glycol, polyvinyl alcohol, polyvinyl pyridine, or a combination thereof.

[0063] In some embodiments, the nanoscale solid-phase catalyst is located near the first membrane layer. The placement of the nanoscale solid-phase catalyst on the surface of the first membrane layer has the positive effect of accelerating the overall water dissociation reaction rate and improving the energy efficiency of the bipolar membrane process.

[0064] According to the embodiments of the present application, when the bipolar membrane is in use, it has a low water dissociation voltage, low energy consumption, high selectivity and stability. Compared with traditional bipolar membranes, it can perform electrochemical energy storage and conversion under high current density and high corrosion environment.

[0065] The bipolar membrane of the present application can be used in electrodialysis, water electrolysis to produce hydrogen, fuel cells, flow batteries, electrochemical synthesis of ammonia, and carbon dioxide electrochemical conversion devices.

[0066] Method for preparing bipolar membrane

[0067] In a second aspect, the present application provides a method for preparing a bipolar membrane, such as Figure 1 As shown, including:

[0068] S100. Providing a first solution and a second solution having a reactive double bond for forming a first film layer and a second film layer, respectively;

[0069] S200. The first solution is brought into contact with the mold to form a plurality of protrusions, and a first film layer is formed by drying;

[0070] S300. Preparing a first film layer having a nanoscale solid-phase catalyst dispersed on the surface;

[0071] S400. The second solution is brought into contact with the first membrane layer having a nano-scale solid-phase catalyst dispersed on the surface thereof to form a plurality of recesses, and the second membrane layer is formed by drying; wherein one of the first solution and the second solution is a cation exchange resin solution and the other is an anion exchange resin solution;

[0072] a bipolar membrane comprising an anion exchange resin and a cation exchange resin through the first solution and the second solution;

[0073] S500. Under the action of ultraviolet light, the reactive double bonds respectively possessed by the first membrane layer and the second membrane layer are reacted to chemically bond the bonding interface between the second membrane layer and the first membrane layer, thereby obtaining the bipolar membrane of the first aspect, wherein a nanoscale solid-phase catalyst is accommodated between the first membrane layer and the second membrane layer.

[0074] In the related art, when preparing bipolar membranes, it is difficult to finely control the structure of the intermediate layer of the bipolar membrane (below the micron scale), and the structure of the intermediate layer is highly random; 2) The preparation method of the intermediate layer structure is complex and costly, making it difficult to achieve large-scale batch production.

[0075] The inventors have discovered that using a mold with specific concave or convex portions creates a corresponding structure for the first membrane layer, indirectly creating a structure that interlocks with the second membrane layer. This allows the bipolar membrane to strengthen its interlocking strength during use due to swelling in water or other dispersion media, effectively preventing separation of the first and second membrane layers. Furthermore, chemical bonding between the materials of the first and second membrane layers, catalyzed by ultraviolet light, leads to crosslinking. This is simple and easy to achieve, improving the connection between the first and second membrane layers.

[0076] In some embodiments, in S200, the first solution is brought into contact with the mold, and a self-leveling method can be used to form a thin covering layer on the mold surface. The second solution is brought into contact with the first film layer, and a self-leveling method can be used to form a thin covering layer on the surface of the first film layer, thereby preparing the second film layer.

[0077] In some embodiments, in S200 , the first solution is an anionic solution, which has a positive effect of assisting cross-linking.

[0078] In some embodiments, after contacting the anion exchange resin solution with the mold in S200 , the method further includes: removing the mold from the surface of the membrane layer;

[0079] In some embodiments, in S200, the mold is a metal mold, which can be made of nickel, iron, aluminum, zinc, copper, or one or more of the above materials.

[0080] In some embodiments, the mold surface may include a nano-protrusion array or a nano-concave array. The nano-protrusion array or the nano-concave array may be grown on the mold surface or may be flexibly separated from the mold. The mold containing the nano-protrusion array may be in the form of a thin sheet, and its thickness may be 0.01 mm to 1 mm, optionally 0.05 mm. The size of the nano-protrusion array or the nano-concave array on the metal sheet is less than 5 microns by 5 microns. The mold preparation method may be: using a metal thin film material as a substrate, and growing a pattern with a certain nanostructure on the surface in a hydrothermal manner in an aqueous solution containing a transition metal.

[0081] In some embodiments, in S200, the transition metal aqueous solution includes at least one of cobalt chloride and nickel chloride, and may also include chloride salts; optionally, the mass ratio of cobalt chloride to nickel chloride is 1:10-10:1, and the concentration range of the transition metal aqueous solution is 0.03M-0.6M, which can be used to regulate different surface morphologies; the transition metal aqueous solution is an alkaline environment, which can be achieved by urea, with a concentration range of 0.04M-0.8M, which can be adjusted to have different surface morphologies; the temperature range during hydrothermal treatment is 80-180°C, and the time is between 30-300min, which can be adjusted to have different surface morphologies.

[0082] In some embodiments, in S200, the mold on the surface of the film layer is removed using an etching solution. The etching solution can be alkaline or acidic, such as NaOH, KOH, concentrated HCl, and concentrated sulfuric acid. The concentration of concentrated sulfuric acid can be 1M, and the concentration of concentrated hydrochloric acid can be 6M.

[0083] In some embodiments, in S200 , after the mold on the surface of the film layer is removed by etching solution, it can be washed with water.

[0084] In some embodiments, in S300 , the nano-scale solid-phase catalyst is dispersed in the first membrane layer by spraying or doctor blade coating, and spraying is optional.

[0085] In some embodiments, in S300, a first membrane layer with a nanoscale solid-phase catalyst dispersed on its surface is prepared; by uniformly dispersing the nanoscale solid-phase catalyst in the first membrane layer, the nanoscale solid-phase catalyst can be used in subsequent applications, such as electrolysis of water.

[0086] In some embodiments, in S400 , the anion exchange resin solution comprises 3% to 17% of anion exchange resin by mass.

[0087] In some embodiments, in S400, the raw material of the anion exchange resin includes one or more of alkyl quaternary ammonium salts, aryl quaternary ammonium salts, quaternary phosphonium salts, and coordinated metal salts.

[0088] In some embodiments, in S400 , the anion exchange resin solution includes an organic solvent, and the organic solvent is selected from dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone, or a combination thereof.

[0089] In some embodiments, in S400 , the solute in the cation exchange resin solution may be a cation exchange resin, and the evaporation temperature of the solvent used is between 50° C. and 100° C.

[0090] In some embodiments, in S500, under the action of ultraviolet light with a wavelength of 254nm-365nm.

[0091] The preparation method of the present application has a simple process, does not involve complicated instruments, is easy to implement industrially, and is convenient for batch production.

[0092] Example

[0093] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used directly without further processing, and all instruments used in the examples are commercially available.

[0094] Examples 1-3

[0095] 1) A 0.05 mm thick Ni sheet was used as a substrate. A patterned template with a certain nanostructure was grown on the surface by hydrothermal means in a 0.15 M divalent cobalt ion / 0.15 M divalent nickel ion chloride solution. 0.2 M urea was added to create an alkaline environment. The hydrothermal time was 180 min and the temperature was 120 ° C. The substrate morphology of the obtained template structure was as follows: Figure 2 As shown;

[0096] 2) A polymer backbone of an anion exchange resin VBQ2PPT with a double bond structure was synthesized by superacid catalyzed polymerization, and then side chains were grafted using 1,6-diiodohexane and 1,1-dimethylbenzylamine. In addition, a cationic membrane resin PSSA having a copolymer of styrene sulfonate and acrylonitrile was obtained by free radical polymerization. VBQ2PPT (terphenyl-piperidone) was prepared into a 2% dimethyl sulfoxide solution, and the solution was cast on the surface of the patterned template structure obtained in 1), and dried at 50°C on a heating table for 6 hours to obtain an anion exchange membrane layer embedded in the inorganic patterned surface;

[0097] 3) The thin film material obtained in 2) is peeled off from the metal substrate and immersed in a 6M hydrochloric acid solution to etch the inorganic nanoparticles embedded on the membrane surface, thereby obtaining a single-layer anion exchange membrane with a surface structure. The bipolar membrane is washed with deionized water several times and dried to obtain the surface structure and cross-sectional structure of the anion exchange layer. Figure 3 、 4 As shown;

[0098] 4) uniformly applying SnO2 catalyst particles with a particle size of approximately 50 nm to one side of the anion exchange membrane layer obtained in 3) having a structured surface;

[0099] 5) Spray a layer of double-bond cation exchange polymer PSSA solution on the anion exchange membrane layer after applying the catalyst, and evaporate the solvent at 100°C to obtain a bipolar membrane material with a physical intercalated structure in the middle layer. Its cross-sectional structure is as follows: Figure 5 shown.

[0100] 6) Irradiate with 254 nm ultraviolet light for 4 h to obtain a bipolar membrane with a physicochemical double interlocking intermediate layer. Specific parameters are shown in Table 1.

[0101] Example 4

[0102] 1) Using a 0.05 mm thick Ni sheet as a substrate, a patterned template with a certain nanostructure was grown on the surface by hydrothermal means in a 0.03 M divalent cobalt ion / 0.03 M divalent nickel ion chloride solution. 0.04 M urea was added to create an alkaline environment. The hydrothermal time was 180 min at a temperature of 120°C to obtain the template structure.

[0103] 2) A polymer backbone of an anion exchange resin VBQ2PPT with a double bond structure was synthesized using a superacid-catalyzed polymerization reaction, and then side-chain grafting was performed using 1,6-diiodohexane and 1,1-dimethylbenzylamine. In addition, a cationic membrane resin PSSA having a copolymer of styrene sulfonate and acrylonitrile was obtained by free radical polymerization. VBQ2PPT (terphenyl-piperidone) was prepared into a 2% DMSO solution, and the solution was cast on the surface of the patterned template structure obtained in 1), and dried on a heating table at 50°C for 6 hours to obtain an anion exchange film layer embedded in the inorganic patterned surface;

[0104] 3) The thin film material obtained in 2) is peeled off from the metal substrate and immersed in a 6M hydrochloric acid solution to etch the inorganic nanoparticles embedded in the membrane surface, thereby obtaining a single-layer anion exchange membrane with a surface structure. The bipolar membrane is rinsed with deionized water multiple times;

[0105] 4) uniformly applying SnO2 catalyst particles with a particle size of approximately 50 nm to one side of the anion exchange membrane layer obtained in 3) having a structured surface;

[0106] 5) spraying a layer of double-bond cation exchange polymer PSSA solution on the anion exchange membrane layer after applying the catalyst, and volatilizing the solvent at 100° C. to obtain a bipolar membrane material with a physical intercalated structure in the middle layer.

[0107] 6) Irradiate with 254 nm ultraviolet light for 4 h to obtain a bipolar membrane with a physicochemical double interlocking intermediate layer. Specific parameters are shown in Table 1.

[0108] Examples 5-12

[0109] The difference between Examples 5-12 of the present application and Example 1 lies in the preparation process parameters, as shown in Table 1.

[0110] Table 1

[0111]

[0112]

[0113] Note: The template structure size test method used is the scanning electron microscope measurement method

[0114] Test section

[0115] 1) Micromorphology detection: The metal template substrate and bipolar membrane of Example 1 were observed using a Zeiss Merlin scanning electron microscope, and the following results were obtained: Figure 2-4 , which illustrates that the metal template substrate and the bipolar membrane have a concave and convex structure, and a first membrane layer and a second membrane layer connection structure.

[0116] 2) Element distribution of bipolar membrane cross section: The element distribution of the bipolar membrane of Example 1 was detected using an Oxford X-max spectrometer to obtain Figure 5 , which shows that the two layers of the membrane and the catalytic layer have formed a physical interlocking structure with a thickness of nearly 2 microns.

[0117] 3) Membrane pressure test

[0118] The bipolar membranes prepared in Examples 1-12 and a commercial bipolar membrane from Japan, model Neosepta BP1, were tested using the four-electrode method. 0.5 M Na2SO4 solution was filled on both sides of a homemade H-type electrolytic cell. Measurements were performed at room temperature. The corresponding voltage was recorded at a scan rate of 2 mV / s over a scan range of 500-1000 mA / cm. -2 . Part of the IV curve relationship is as follows Figure 6 shown.

[0119] Table 2

[0120]

[0121]

[0122] 3) Bipolar membrane stability test

[0123] The bipolar membrane prepared in Example 1-12 was placed in a 0.5M Na2SO4 solution for long-term continuous electrolysis, and the changes in the transmembrane pressure drop at both ends were detected. Figure 7 As shown, the water dissociation stability curve of the bipolar membrane section at a current density of 100mA cm-2 is measured as follows Figure 7 During the continuous electrolysis process of nearly 300 hours, the transmembrane voltage drop of the physical and chemical double interlocking intermediate layer bipolar membrane prepared by the present invention remained at about 0.69V, with no obvious attenuation.

[0124] The bipolar membrane of the present application is interlocked in physical structure and bonded in chemical structure. When the membrane layer swells in a water system, there is an interlocking effect between the two membrane layers. At this time, the stress generated by the swelling is parallel to the middle interface rather than perpendicular to it, making it difficult for the two membrane layers to be delaminated in structure. Traditional two-dimensional bipolar membranes are prone to delamination in water systems, which in turn affects the long-term water dissociation stability of the bipolar membrane. The interlocking structure of the middle layer of the physical and chemical double interlocking middle layer bipolar membrane can strengthen the bond between the two membrane layers, and thus exhibit better water dissociation stability under high current and long-term electrolysis.

[0125] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and such modifications or substitutions should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A bipolar membrane comprising: The first membrane layer comprises an anion exchange resin matrix, and the surface of the first membrane layer comprises a plurality of protrusions. a second membrane layer comprising a cation exchange resin matrix, wherein a surface of the second membrane layer comprises a plurality of recesses, wherein the first membrane layer and the second membrane layer are stacked, the protrusions and the recesses engage with each other, and a bonding interface between the second membrane layer and the first membrane layer comprises chemical bonding; and a nanoscale solid-phase catalyst contained between the first membrane layer and the second membrane layer; The bipolar membrane comprises the following preparation method: providing a first solution and a second solution having reactive double bonds for forming a first film layer and a second film layer, respectively; placing the first solution in contact with the mold to form a plurality of protrusions, and forming a first film layer by drying; preparing the first membrane layer having nano-scale solid-phase catalyst dispersed on the surface; contacting a second solution with the first membrane layer having a nanoscale solid-phase catalyst dispersed on its surface to form a plurality of recesses, and drying the solution to form the second membrane layer; wherein one of the first solution and the second solution is a cation exchange resin solution and the other is an anion exchange resin solution; Under the action of ultraviolet light, the reactive double bonds of the first membrane layer and the second membrane layer react, so that the bonding interface between the second membrane layer and the first membrane layer is chemically bonded to obtain the bipolar membrane.

2. The bipolar membrane according to claim 1, wherein The surface of the first film layer includes a convex portion array; the surface of the second film layer includes a concave portion array, and the convex portion array and the concave portion array are embedded with each other.

3. The bipolar membrane according to claim 2, characterized in that The unit loading amount of the nano-scale solid-phase catalyst in the thickness direction of the bipolar membrane is 0.01-1 mg cm -2 .

4. The bipolar membrane according to claim 3, characterized in that The unit loading amount of the nano-scale solid-phase catalyst in the thickness direction of the bipolar membrane is 0.06-0.08 mg cm -2 .

5. The bipolar membrane according to claim 1, characterized in that The nanoscale solid phase catalyst is selected from metal oxides, polymers or a combination thereof.

6. The bipolar membrane according to claim 1, characterized in that The volume particle size Dv50 of the nano-scale solid phase catalyst is 5-100 nm.

7. The bipolar membrane according to claim 6, characterized in that The volume particle size Dv50 of the nano-scale solid phase catalyst is 15-25 nm.

8. The bipolar membrane according to claim 7, characterized in that The volume particle size Dv50 of the nano-scale solid phase catalyst is 20 nm.

9. The bipolar membrane according to claim 5, characterized in that The metal oxide is selected from tin dioxide, iridium dioxide, nickel oxide, ferric hydroxide or a combination thereof.

10. The bipolar membrane according to claim 5, characterized in that The polymer is selected from polyethylene glycol, polyvinyl alcohol, polyvinyl pyridine or a combination thereof.

11. The bipolar membrane according to claim 3, characterized in that The nanoscale solid-phase catalyst is close to the first membrane layer.

12. The bipolar membrane according to claim 1, characterized in that The anion exchange resin solution comprises 3% to 17% of anion exchange resin by mass.

13. The bipolar membrane according to claim 1, characterized in that The raw materials of the anion exchange resin include one or more of alkyl quaternary ammonium salts, aryl quaternary ammonium salts, quaternary phosphonium salts, and coordinated metal salts.

14. The bipolar membrane according to claim 1, characterized in that The anion exchange resin solution includes an organic solvent, and the organic solvent is selected from dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone or a combination thereof.

15. The bipolar membrane according to claim 1, characterized in that After the anion exchange resin solution is brought into contact with the mold, the method further includes: removing the mold from the surface of the membrane layer.

16. The bipolar membrane according to claim 1, characterized in that The mold is made of metal.

17. The bipolar membrane according to claim 16, characterized in that The mold on the surface of the film layer is removed by etching solution.

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