Composite diaphragm and preparation method and application thereof

Abstract

The present application relates to the field of hydrogen production membranes by electrolysis of water, and provides a composite membrane and a preparation method and application thereof, wherein the composite membrane comprises: a membrane body having a first surface and a second surface arranged opposite to each other, and a side surface enclosed by the first surface and the second surface to form the membrane body; a sealing structure, wherein the sealing structure covers the edge area of ​​the first surface and the edge area of ​​the second surface in the membrane body, and completely covers the side surface of the membrane body. During the assembly process of the composite membrane of the present application, since the side edge of the composite membrane is covered by the sealing structure, the problem of leakage caused by the exposed side edge of the membrane can be avoided, and the sealing structure located on the surfaces on both sides of the edge of the membrane body during the assembly process can avoid sharp structures such as polar plates or sealing rings from directly contacting the membrane, thereby effectively protecting the edge of the membrane and avoiding damage to the edge of the membrane under the shear force of the seal pressing, and has the characteristics of simple structure, good sealing effect and high edge shear strength.

Description

Technical Field

[0001] The present application relates to the technical field of diaphragms for hydrogen production by water electrolysis, and in particular to a composite diaphragm and a preparation method and application thereof. Background Art

[0002] Water electrolysis technology is an important means of producing green hydrogen in the future. It can be divided into three methods: alkaline water electrolysis (AWE), proton exchange membrane water electrolysis, and solid oxide water electrolysis. Among them, AWE hydrogen production technology is the earliest developed and the most mature technology.

[0003] The structures of electrolyzer devices mainly include circular electrolyzers and square electrolyzers. The diaphragm is the core component of alkaline liquid hydrogen production, and plays an important role in blocking hydrogen and oxygen and establishing ion transmission pathways in alkaline electrolyzers. However, when assembling the diaphragm to the electrolyzer device, the circular electrolyzer is sealed by completely pressing the diaphragm with a sealing gasket. The sharp sealing gasket will form a strong shearing effect on the composite diaphragm and cause the diaphragm to be damaged, resulting in failure of the seal of the electrolyzer, posing a safety risk. At the same time, sharp welding point protrusions on the edges of components such as plates or electrodes will also pierce the diaphragm and cause a short circuit between the anode and cathode. The design of the square electrolyzer requires that the diaphragm area is larger than the sealing gasket. At this time, the edge of the diaphragm is partially exposed to the periphery of the electrolyzer. Due to the porous structure of the composite diaphragm, during the operation of the electrolyzer, the alkaline solution will gradually seep out from the part of the diaphragm exposed outside the electrolyzer, causing a safety accident. Summary of the invention

[0004] Based on this, an embodiment of the present application provides a composite diaphragm with good edge sealing effect and no edge damage, and a preparation method and application thereof.

[0005] In a first aspect, the present application provides a composite diaphragm, the composite diaphragm comprising:

[0006] A diaphragm body, comprising a first surface and a second surface arranged opposite to each other, and a side surface enclosed by the first surface and the second surface to form the diaphragm body;

[0007] A sealing structure covers the edge area of ​​the first surface and the edge area of ​​the second surface of the diaphragm body and completely covers the side surface of the diaphragm body.

[0008] In some embodiments, the sealing structure includes a toughness support layer and a protective layer stacked in sequence in a direction away from the diaphragm body.

[0009] In some embodiments, the sealing structure further includes a strengthening layer, wherein the strengthening layer is disposed between the toughness support layer and the protective layer.

[0010] In some embodiments, the toughness support layer has a thickness of 1 mm to 3 mm.

[0011] In some embodiments, the thickness of the protective layer is 1 mm to 5 mm.

[0012] In some embodiments, the impact toughness value of the tough support layer is 50 J / m to 150 J / m.

[0013] In some embodiments, the material of the tough support layer includes a polyacrylate solidified material, and the polyacrylate solidified material is formed by curing an acrylate resin with a first curing agent.

[0014] In some embodiments, the acrylate resin includes at least one of methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, and propylene acrylate.

[0015] In some embodiments, the first curing agent includes at least one of dibenzoyl peroxide, tert-butyl perbenzoate, phenol peroxide, acrylamide peroxide, diisopropylbenzene peroxide, maleic anhydride, acrylic anhydride, tributylamine, and ethylenediamine.

[0016] In some embodiments, the material of the protective layer includes a cured epoxy resin, and the cured epoxy resin is formed by curing epoxy resin with a second curing agent.

[0017] In some embodiments, the epoxy resin includes at least one of a glycidyl ether epoxy resin, an amino epoxy resin, a glycidyl ester epoxy resin, an epoxidized olefin resin, a hydantoin epoxy resin, a brominated epoxy resin, and a phosphated epoxy resin.

[0018] In some embodiments, the second curing agent includes at least one of an amine curing agent, an acid anhydride curing agent, a delayed curing agent, and a composite curing agent.

[0019] In some embodiments, the reinforcement layer is in a porous mesh structure.

[0020] In some embodiments, the mesh size of the pore structure of the reinforcement layer is 40 meshes to 60 meshes.

[0021] In some embodiments, the material of the reinforcement layer includes at least one of polyester, polyphenylene sulfide, polyurethane, polyacrylonitrile, polyetheretherketone and sulfonated polyetheretherketone.

[0022] In some embodiments, a plurality of through holes penetrating the diaphragm body along the thickness direction are formed on the edge of the diaphragm body; the sealing structure further includes a support column, and the support column is disposed in the through hole.

[0023] In some embodiments, the through holes are evenly opened along the edge of the diaphragm body.

[0024] In some embodiments, the diameter of the through hole is 2 mm to 10 mm.

[0025] In some embodiments, the material of the sealing structure includes at least one of polysulfone, polyethersulfone, polyphenylsulfone, polyvinylidene fluoride, and polymethyl methacrylate.

[0026] In some embodiments, the membrane body includes a first porous layer, a mesh support layer, and a second porous layer stacked in sequence.

[0027] In some embodiments, the mesh support layer is at least partially exposed outside the first porous layer and the second porous layer, and the exposed area of ​​the mesh support layer extends into the sealing structure.

[0028] In a second aspect, the present application provides a method for preparing the composite diaphragm as described in the first aspect, the preparation method comprising:

[0029] At the edge portion of the diaphragm body, a sealing material is used to cover at least a portion of the surface of both sides of the diaphragm body, and completely covers the side surfaces of the diaphragm body to form the sealing structure.

[0030] In a third aspect, the present application provides an application of the composite membrane as described in the first aspect, wherein the composite membrane is used for producing hydrogen by alkaline water electrolysis.

[0031] Compared with the traditional technology, this application has at least the following beneficial effects:

[0032] The composite diaphragm of the present application forms a sealing structure at the edge of the diaphragm body, and the sealing structure can cover the side of the diaphragm body and partially cover the two side surfaces of the diaphragm body. During the assembly process of the diaphragm, since the side of the composite diaphragm is covered by the sealing structure, the problem of leakage caused by the exposed side of the diaphragm is avoided. In addition, the sealing structure located on the two side surfaces of the edge of the diaphragm body during the assembly process can prevent sharp structures such as polar plates or sealing rings from directly contacting the diaphragm, effectively protecting the edge of the diaphragm and avoiding damage to the edge of the diaphragm under the shear force of the seal pressing. The present application has the characteristics of simple structure, good sealing effect and high edge shear strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic structural diagram of a composite diaphragm provided in one embodiment of the present application;

[0034] Figure 2 A schematic structural diagram of another composite diaphragm provided in one embodiment of the present application;

[0035] Figure 3A schematic structural diagram of another composite diaphragm provided in one embodiment of the present application;

[0036] Figure 4 A schematic diagram of the top view of the composite diaphragm provided in one embodiment of the present application.

[0037] Among them, 100-diaphragm body; 100a-first surface; 100b-second surface; 100c-side; 110-first porous layer; 120-net support layer; 130-second porous layer; 200-sealing structure; 210-tough support layer; 220-protective layer; 230-strengthening layer; 240-support column. DETAILED DESCRIPTION

[0038] Below in conjunction with the embodiments and examples, the present application is further described in detail. These embodiments and examples are only used to illustrate the present application and are not used to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the understanding of the disclosure of the present application more thorough and comprehensive. It should also be understood that the present application can be implemented in many different forms, and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the present application, and the equivalent form obtained also falls within the protection scope of the present application. In addition, in the description below, a large number of specific details are given in order to provide a more comprehensive understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0040] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0041] In this application, the terms "first", "second", etc. in "the first aspect", "the second aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0042] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0043] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for a broad range of quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0044] All documents mentioned in this application are cited as references in this application, just as each document is cited as reference separately. Unless they conflict with the application purpose and / or technical solution of this application, the cited documents involved in this application are cited with all contents and all purposes. When the cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the cited documents are involved in this application, the examples and preferred methods of the cited relevant technical features can also be incorporated into this application as references, but are limited to the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be modified adaptively according to the description of this application.

[0045] In the traditional technology, the diaphragm has a porous structure and has problems such as poor edge sealing effect. Technicians increase the pressing force between the sealing gasket and the diaphragm to improve the sealing effect, but it is easy to cause shearing between the diaphragm and the sealing gasket, causing damage to the diaphragm. Therefore, technicians modify the diaphragm substrate to improve the mechanical strength. However, after the mechanical strength modification of some diaphragms with excellent performance, although the mechanical strength can be improved, its hydrophilicity and ion conductivity will decrease. Therefore, the present application adds a sealing structure to the edge of the diaphragm. The sealing structure effectively avoids the side seepage problem caused by the porous structure by coating the edge of the diaphragm, thereby improving the sealing effect. In addition, the sealing structure can also avoid direct contact between the sealing gasket or the plate and the diaphragm, thereby improving the structural strength of the diaphragm edge, and can be applicable to various types of diaphragm bodies.

[0046] The first aspect of the present application provides a composite diaphragm, such as Figure 1 As shown, the composite diaphragm comprises:

[0047] The diaphragm body 100 has a first surface 100a and a second surface 100b that are opposite to each other, and a side surface 100c that is enclosed by the first surface 100a and the second surface 100b to form the diaphragm body 100;

[0048] The sealing structure 200 covers the edge area of ​​the first surface 100 a and the edge area of ​​the second surface 100 b of the diaphragm body 100 , and completely covers the side surface 100 c of the diaphragm body 100 .

[0049] The composite diaphragm of the present application forms a sealing structure at the edge of the diaphragm body, and the sealing structure can cover the side of the diaphragm body and partially cover the two side surfaces of the diaphragm body. During the assembly process of the diaphragm, since the side of the composite diaphragm is covered by the sealing structure, the problem of leakage caused by the exposed side of the diaphragm is avoided. In addition, the sealing structure located on the two side surfaces of the edge of the diaphragm body during the assembly process can prevent sharp structures such as polar plates or sealing rings from directly contacting the diaphragm, effectively protecting the edge of the diaphragm and avoiding damage to the edge of the diaphragm under the shear force of the seal pressing. The present application has the characteristics of simple structure, good sealing effect and high edge shear strength.

[0050] In some embodiments, the distance between the inner edge of the edge area of ​​the sealing structure covering the first surface and / or the second surface and the edge of the diaphragm body is independently 1 mm to 10 mm, for example, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, 6.0 mm, 7.0 mm, 8.0 mm, 9.0 mm or 10.0 mm, and can be 1 mm to 5 mm. Figure 1 a1 represents the distance between the inner edge of the first surface edge area covered by the sealing structure and the edge of the diaphragm body, and a2 represents the distance between the inner edge of the second surface edge area covered by the sealing structure and the edge of the diaphragm body.

[0051] In some embodiments, the distance between the sealing structure and the side of the diaphragm body is 1 mm to 10 mm, for example, 1.0 mm, 2.0 mm, 3.0 mm, 4.0 mm, 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, 7.0 mm, 7.5 mm, 8.0 mm, 8.5 mm, 9.0 mm, 9.5 mm or 10.0 mm, and can be 5 mm to 10 mm. Figure 1 b represents the distance between the sealing structure and the side of the diaphragm body.

[0052] It is understood that the size of the sealing structure can be adjusted according to the sealing requirements of the composite diaphragm.

[0053] In some embodiments, Figure 2 As shown, the sealing structure 200 includes a toughness support layer 210 and a protection layer 220 which are sequentially stacked in a direction away from the diaphragm body 100 .

[0054] The present application utilizes a sealing structure formed by stacking a tough support layer and a protective layer, wherein the tough support layer has a certain toughness and can avoid damage to the diaphragm during the sealing extrusion process when the diaphragm is assembled; the protective layer can protect the tough support layer from chemical corrosion caused by large-area contact with alkaline solutions, and further improve the mechanical strength of the sealing structure.

[0055] In some embodiments, Figure 2 As shown, the sealing structure 200 further includes a strengthening layer 230 , and the strengthening layer 230 is disposed between the toughness support layer 210 and the protective layer 220 .

[0056] In the present application, a strengthening layer is added to improve the bonding strength between the toughness support layer and the protective layer.

[0057] In some embodiments, the tough support layer has a thickness of 1 mm to 3 mm, for example, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm or 3.0 mm.

[0058] In some embodiments, the thickness of the protective layer is 1 mm to 5 mm, for example, it can be 1.0 mm, 1.4 mm, 1.8 mm, 2.2 mm, 2.6 mm, 3.0 mm, 3.4 mm, 3.8 mm, 4.2 mm, 4.6 mm or 5.0 mm.

[0059] In some embodiments, the impact toughness value of the tough support layer is 50 J / m to 150 J / m, for example, 50 J / m, 60 J / m, 70 J / m, 80 J / m, 90 J / m, 100 J / m, 110 J / m, 120 J / m, 130 J / m, 140 J / m or 150 J / m. It is understood that the impact toughness value can be obtained by testing according to standard ASTM D256 2023.

[0060] The present application controls the impact toughness value of the tough support layer to ensure the sealing and protection effect of the composite diaphragm. If the toughness is relatively low, the protection effect may be poor, and the tough support layer may fail during the assembly process, which may lead to a decrease in sealing; if the toughness is relatively high, the bonding strength between the tough support layer and the diaphragm is low during the preparation process, which may cause a decrease in sealing effect.

[0061] The present application controls the impact toughness value of the toughness support layer material, thereby having a certain energy absorption effect, and effectively avoiding mechanical shear damage to the diaphragm during the sealing process through elasticity.

[0062] In some embodiments, the material of the tough support layer includes a polyacrylate solidified material, and the polyacrylate solidified material is formed by curing an acrylic resin with a first curing agent.

[0063] In the present application, the tough support layer is made of a tough material in contact with the diaphragm body, which can protect the diaphragm body from being damaged by the plate compression force during installation. More preferably, it is an acrylic polymer material, which not only has good bonding properties and toughness, but also has good bonding properties to ensure that the diaphragm body and the tough support layer are tightly combined under the premise of preliminary sealing.

[0064] In some embodiments, the acrylate resin includes at least one of methyl acrylate (MMA), ethyl acrylate (EMA), butyl acrylate (BA), isobutyl acrylate (IBA), and acrylic acrylate (PA).

[0065] In some embodiments, the first curing agent includes at least one of dibenzoyl peroxide, tert-butyl perbenzoate, phenol peroxide, acrylamide peroxide, diisopropylbenzene peroxide, maleic anhydride, acrylic anhydride, tributylamine and ethylenediamine. Tert-butyl perbenzoate is preferred. Tert-butyl perbenzoate has stable performance compared to conventional organic peroxides, and the molecular weight distribution of the resin generated by the reaction is narrow, which is conducive to curing.

[0066] In some embodiments, the material of the protective layer includes epoxy resin cured material, and the epoxy resin cured material is formed by curing epoxy resin with a second curing agent.

[0067] The protective layer in the present application is made of epoxy resin polymer material, which has good strength and chemical resistance, can enhance the overall strength of the sealing structure, protect it from the corrosion of high-temperature alkali solution in the electrolytic cell, and further enhance the sealing effect of the sealing structure.

[0068] In some embodiments, the epoxy resin includes at least one of glycidyl ether epoxy resin, amino epoxy resin, glycidyl ester epoxy resin, epoxidized olefin resin, hydantoin epoxy resin, brominated epoxy resin and phosphated epoxy resin, preferably glycidyl ether epoxy resin.

[0069] In some embodiments, the glycidyl ether epoxy resin includes at least one of bisphenol A epoxy resin, bisphenol S epoxy resin, bisphenol F epoxy resin, epoxy novolac resin, 1,1,2,2-tetra(p-hydroxyphenyl)ethane tetraglycidyl ether epoxy resin and resorcinol bisglycidyl ether epoxy resin, preferably bisphenol F epoxy resin.

[0070] In some embodiments, the second curing agent includes at least one of an amine curing agent, an acid anhydride curing agent, a delayed curing agent, and a composite curing agent, preferably an amine curing agent.

[0071] Optionally, the amine curing agent is selected from at least one of ethylenediamine, diethylenediamine, triethylenetetramine, polypropylenediamine and methylcyclohexanediamine, preferably methylcyclohexanediamine.

[0072] In some embodiments, the reinforcement layer is in a porous mesh structure, such as a porous fabric.

[0073] In some embodiments, the mesh number of the pore structure of the reinforcement layer is 40 mesh to 60 mesh, for example, it can be 40 mesh, 42 mesh, 44 mesh, 46 mesh, 48 mesh, 50 mesh, 52 mesh, 54 mesh, 56 mesh, 58 mesh or 60 mesh.

[0074] In some embodiments, the material of the reinforcement layer includes at least one of polyester (PET), polyphenylene sulfide (PPS), polyurethane (PU), polyphenylene nitrile (PAN), polyetheretherketone (PEEK) and sulfonated polyetheretherketone (SPEEK).

[0075] The present application adds a strengthening layer between the tough support layer and the protective layer. The strengthening layer adopts a porous mesh structure, such as polyphenylene sulfide fabric, which can not only strengthen the interface bonding force between the tough support layer and the protective layer, but also improve the mechanical strength of the sealing structure.

[0076] In some embodiments, Figure 3 and Figure 4 As shown, a plurality of through holes penetrating the diaphragm body along the thickness direction are opened at the edge of the diaphragm body 100; the sealing structure 200 further includes a support column 240, and the support column 240 is disposed in the through hole.

[0077] The present application forms a through-hole structure on the edge of the diaphragm body and fills the support column of the sealing structure into the through-hole. The support column not only realizes the anchoring of the sealing structure to the diaphragm body, but also provides a certain supporting force during the sealing compression process, thereby preventing the sealing structure from squeezing the diaphragm body and causing damage.

[0078] In some embodiments, the support column and the sealing structure are integrally formed, or the support column and the sealing structure are connected or bonded via a mechanical structure.

[0079] In some embodiments, the through holes are evenly opened along the edge of the diaphragm body.

[0080] In some embodiments, the diameter of the through hole is 2 mm to 10 mm, for example, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm. It can be 2 mm to 5 mm. The above selection of the diameter of the through hole in the present application can effectively ensure the connection stability between the sealing structure and the diaphragm body.

[0081] In some embodiments, the sealing structure can be made of a single material. The material of the sealing structure includes at least one of polysulfone (PSU), polyethersulfone (PES), polyphenylsulfone (PPSU), polyvinylidene fluoride (PVDF) and polymethyl methacrylate (PMMA). It is understood that the material of the support column can be the same as the material of the sealing structure, and can be integrally formed by injection molding with the sealing structure.

[0082] In some embodiments, Figure 2 As shown, the diaphragm body 100 includes a first porous layer 110, a mesh support layer 120 and a second porous layer 130 which are stacked in sequence.

[0083] In some embodiments, the mesh support layer 120 is at least partially exposed outside the first porous layer 110 and the second porous layer 130, and the exposed area of ​​the mesh support layer 120 extends into the sealing structure 200. Optionally, the extended length of the mesh support layer 120 in the exposed area is 0.5 mm to 2 mm.

[0084] In the present application, the mesh support layer in the diaphragm body extends into the sealing structure and can serve as a skeleton of the sealing structure, thereby improving the strength of the sealing structure and the bonding strength between the sealing structure and the diaphragm body.

[0085] In some embodiments, the sealing structure 200 includes a stacked tough support layer 210 and a protective layer 220 , and the area of ​​the mesh support layer 120 where the first porous layer 110 and the second porous layer 130 are exposed extends to the interior of the tough support layer 210 .

[0086] In some embodiments, the material of the mesh support layer includes at least one of polyester (PET), polyphenylene sulfide (PPS), polyurethane (PU), polyacrylonitrile (PAN), polyetheretherketone (PEEK) and sulfonated polyetheretherketone (SPEEK), preferably polyphenylene sulfide porous fabric.

[0087] In some embodiments, the material of the first porous layer and the material of the second porous layer independently include at least one of polysulfone (PSU), polyethersulfone (PES), polyphenylsulfone (PPSU), polyvinylidene fluoride (PVDF) and polymethyl methacrylate (PMMA).

[0088] In the present application, the mesh support layer is preferably a porous fabric of polyphenylene sulfide. Since polyphenylene sulfide (PPS) has a high melting point and a high glass transition temperature, excellent acid and alkali resistance and high flame retardancy, and exhibits excellent creep resistance and wear resistance, it is a semi-crystalline polymer that is resistant to high temperatures, chemical compounds and has high mechanical strength, and is well suited for alkaline water electrolysis to produce hydrogen.

[0089] In some embodiments, the first porous layer has a thickness of 0.05 mm to 0.15 mm and a porosity of 40% to 60%.

[0090] In some embodiments, the second porous layer has a thickness of 0.05 mm to 0.15 mm and a porosity of 40% to 60%.

[0091] In some embodiments, the mesh support layer has a thickness of 0.05 mm to 0.20 mm.

[0092] In some embodiments, the mesh size of the mesh support layer is 10-200 mesh, for example, it can be 10 mesh, 20 mesh, 40 mesh, 60 mesh, 80 mesh, 100 mesh, 120 mesh, 140 mesh, 160 mesh, 180 mesh or 200 mesh.

[0093] The second aspect of the present application provides a method for preparing the composite diaphragm according to the first aspect, the preparation method comprising:

[0094] At the edge portion of the diaphragm body, a sealing material is used to cover at least a portion of the surface of both sides of the diaphragm body, and completely covers the side surfaces of the diaphragm body to form the sealing structure.

[0095] In some embodiments, the sealing structure includes a toughness support layer, a strengthening layer and a protective layer stacked in sequence, and the preparation method includes:

[0096] A tough support layer is attached along the edge of the diaphragm body, so that the tough support layer covers at least part of the two side surfaces of the diaphragm body respectively and completely covers the side surfaces of the diaphragm body;

[0097] Then, a strengthening layer and a protective layer are sequentially attached to the surface of the tough support layer to form a composite diaphragm with a sealing structure;

[0098] Alternatively, the preparation method comprises:

[0099] A laminated body including a tough support layer, a strengthening layer and a protective layer is preformed, and the laminated body is attached along the edge of the diaphragm body to form a composite diaphragm with a sealing structure.

[0100] In some embodiments, the sealing structure further includes a support column, and the sealing structure is formed by injection molding. The preparation method includes:

[0101] An injection molded part with a sealing structure shape is formed at the edge of the diaphragm body, and a sealing material is injected into the injection molded part to form a sealing structure covering the diaphragm body, wherein the support column in the sealing structure is filled with the sealing material to the through hole at the edge of the diaphragm body and is formed integrally with the sealing structure.

[0102] A third aspect of the present application provides an application of the composite membrane as described in the first aspect, wherein the composite membrane is used for producing hydrogen by alkaline water electrolysis.

[0103] In some embodiments, the composite diaphragm is applied to an alkaline water electrolysis device, which includes an electrolytic cell, a cathode electrode, a composite diaphragm, an anode electrode, a first sealing gasket and a second sealing gasket. The electrolytic cell is filled with electrolyte, and the cathode electrode, the composite diaphragm and the anode electrode are stacked in sequence. The planar size of the composite diaphragm is larger than that of the cathode electrode and the anode electrode. The first sealing gasket and the second sealing gasket are sleeved on the sealing structure at the edge of the composite diaphragm, and the first sealing gasket and the second sealing gasket are pressed together to seal.

[0104] In some embodiments, the composite membrane is applied to an alkaline water electrolysis device, which includes an electrolytic cell, a cathode electrode, a composite membrane and an anode electrode. The cathode electrode, the composite membrane and the anode electrode are stacked, and the sealing structure in the composite membrane is in contact and sealed with the cathode and the anode.

[0105] The embodiments of the present application will be described in detail below in conjunction with examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are preferably referred to the guidance provided in the present application, and can also be based on the experimental manual or normal conditions in this area, can also be based on the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0106] The diaphragm body used in the following embodiments and comparative examples includes a first porous layer, a mesh support layer and a second porous layer stacked in sequence, wherein the material of the first porous layer is polysulfone, with a thickness of 150 μm and a porosity of 50%; the material of the second porous layer is polysulfone, with a thickness of 150 μm and a porosity of 50%; the mesh support layer is a polyphenylene sulfide porous fabric with a mesh size of 50 and a thickness of 200 μm.

[0107] Example 1

[0108] Methyl acrylate and tert-butyl perbenzoate are mixed in a mass ratio of 50:50 to obtain an acrylate mixture;

[0109] The acrylic ester mixture is coated on the edge of the diaphragm body, the mesh support layer in the diaphragm body is extended to the edge of the first porous layer and the second porous layer, the extension length is 1.5 mm, and a tough support layer with a thickness of 2 mm is formed after curing. The tough support layer covers the first surface and the second surface of the diaphragm body, and the distance from the edge of the diaphragm body is 4 mm. The tough support layer is coated on the surface of both sides of the diaphragm body and completely covers the side of the diaphragm body. The impact toughness value of the tough support layer is 80 J / m;

[0110] Covering the toughness support layer with sulfonated polyetheretherketone fabric with a mesh number of 50 to form a reinforcement layer;

[0111] Bisphenol F epoxy resin and methylcyclohexanediamine in a mass ratio of 55:45 are mixed to obtain an epoxy resin mixture; the epoxy resin mixture is coated on the reinforcement layer, and a protective layer with a thickness of 3 mm is formed after curing.

[0112] Example 2

[0113] Ethyl acrylate and tributylamine are mixed in a mass ratio of 40:60 to obtain an acrylate mixture;

[0114] The acrylic ester mixture is coated on the edge of the diaphragm body, and after curing, a tough support layer with a thickness of 1 mm is formed. The tough support layer is coated on the surface of both sides of the diaphragm body and completely covers the side of the diaphragm body. The size of the tough support layer coated on the diaphragm body is 2 mm, and the impact toughness value of the tough support layer is 75 J / m;

[0115] A polyphenylene sulfide fabric with a mesh number of 40 is covered on the toughness support layer to form a reinforcement layer;

[0116] Bisphenol A epoxy resin and diethylenediamine are mixed in a mass ratio of 50:50 to obtain an epoxy resin mixture; and the epoxy resin mixture is coated on the reinforcement layer to form a protective layer with a thickness of 5 mm after curing.

[0117] Example 3

[0118] Mixing propylene acrylate and acrylamide peroxide in a mass ratio of 60:40 to obtain an acrylate mixture;

[0119] The acrylic ester mixture is coated on the edge of the diaphragm body, and after curing, a tough support layer with a thickness of 3 mm is formed. The tough support layer is coated on the surface of both sides of the diaphragm body and completely covers the side of the diaphragm body. The size of the tough support layer coated on the diaphragm body is 4 mm, and the impact toughness value of the tough support layer is 70 J / m;

[0120] A polyacrylonitrile fabric with a mesh number of 60 is covered on the toughness support layer to form a reinforcement layer;

[0121] The epoxy resin mixture is obtained by mixing hydantoin epoxy resin and anhydride curing agent in a mass ratio of 65:35; and the epoxy resin mixture is coated on the strengthening layer to form a protective layer with a thickness of 1 mm after curing.

[0122] Example 4

[0123] An injection molded part having a sealing structure shape is arranged at the edge of the diaphragm body, and the mesh support layer in the diaphragm body extends outward to the outside of the first porous layer and the second porous layer, and the extension length is 1 mm;

[0124] Polysulfone resin is added into the injection molded part, and after solidification and molding, a sealing structure covering the edge of the diaphragm body is obtained. The surface of the sealing structure is 3 mm away from the surface of the diaphragm body. The impact toughness value of the polysulfone resin is 65 J / m.

[0125] Example 5

[0126] Through holes with a diameter of 5 mm are evenly opened along the edge of the diaphragm body; then an injection molded part with a sealing structure shape is arranged on the edge of the diaphragm body;

[0127] Polyethersulfone resin is added into the injection molded part, and the polyethersulfone resin is filled into the through hole. After solidification and molding, a sealing structure with a support column is obtained. The sealing structure covers the edge of the diaphragm body. The surface of the sealing structure is 3 mm away from the surface of the diaphragm body. The impact toughness value of the polyethersulfone resin is 80 J / m.

[0128] Example 6

[0129] A composite diaphragm was prepared according to the method of Example 1, the only difference being that the edge of the mesh support layer in the diaphragm body overlapped with the first porous layer and the second porous layer.

[0130] Example 7

[0131] A composite diaphragm was prepared according to the method of Example 1, the only difference being that the sealing structure did not have a reinforcement layer.

[0132] Example 8

[0133] A composite diaphragm was prepared according to the method of Example 1, the only difference being that the tough support layer was replaced by polyamide, whose impact toughness value was 30 J / m.

[0134] Example 9

[0135] A composite diaphragm was prepared according to the method of Example 1, the only difference being that the tough support layer was replaced by glass fiber reinforced polycarbonate, whose impact toughness value was 350 J / m.

[0136] Comparative Example 1

[0137] The diaphragm body in Example 1 is directly used as the composite diaphragm.

[0138] The composite diaphragms in the above-mentioned embodiments and comparative examples were subjected to edge alkali absorption rate test and compression strength test to characterize their sealing effect and protection effect.

[0139] The alkali absorption rate test is carried out in accordance with the provisions of 4.10 of SJ / T 10171-2016.

[0140] The compression strength test is carried out in accordance with the provisions of GB / T 2679.10-1993, Part 8.

[0141] The test results are shown in Table 1.

[0142] Table 1

[0143]

[0144] From the above table we can see that:

[0145] (1) Compared with Example 6, it can be seen that the mesh support layer in the diaphragm body of the present application extends into the sealing structure and can serve as the skeleton of the sealing structure, which can not only improve the strength of the sealing structure, but also improve the bonding strength between the sealing structure and the diaphragm body.

[0146] (2) Compared with Example 7, it can be seen that the present application adds a reinforcement layer between the tough support layer and the protective layer. The reinforcement layer adopts a porous mesh structure, such as polyphenylene sulfide fabric, which can not only strengthen the interface bonding force between the tough support layer and the protective layer, but also improve the mechanical strength of the sealing structure.

[0147] (3) Compared with Examples 8-9, it can be seen that the impact toughness value of the toughness support layer of the present application is controlled, and it has the advantages of excellent sealing and good protection effect. Materials with lower toughness have no significant protective effect on the diaphragm, and materials with too high toughness cannot simultaneously have good bonding strength with the diaphragm surface, thereby reducing the sealing effect.

[0148] (4) Compared with Example 1, it can be seen that the sealing structure added to the edge of the composite diaphragm body of the present application can effectively improve the sealing effect and mechanical strength of the diaphragm. Specifically, the composite diaphragm of the present application forms a sealing structure at the edge of the diaphragm body, and the sealing structure can cover the side of the diaphragm body and partially cover the two side surfaces of the diaphragm body. During the assembly of the diaphragm, the side of the composite diaphragm is covered by the sealing structure, thereby avoiding the problem of leakage caused by the exposed side of the diaphragm. In addition, the sealing structure located on the two side surfaces of the edge of the diaphragm body during the assembly process can prevent sharp structures such as polar plates or sealing rings from directly contacting the diaphragm, effectively protecting the edge of the diaphragm and avoiding damage to the edge of the diaphragm under the shear force of the seal. The present application has the characteristics of simple structure, good sealing effect and high edge shear strength.

[0149] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0150] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A composite diaphragm, characterized in that: The composite diaphragm comprises: A diaphragm body having a first surface and a second surface arranged opposite to each other, and a side surface enclosed by the first surface and the second surface to form the diaphragm body, wherein the diaphragm body comprises a first porous layer, a mesh support layer and a second porous layer stacked in sequence; A sealing structure, wherein the sealing structure covers the edge region of the first surface and the edge region of the second surface of the diaphragm body and completely covers the side of the diaphragm body, wherein the sealing structure comprises a toughness support layer, a strengthening layer and a protective layer stacked in sequence in a direction away from the diaphragm body; the sealing structure further comprises a strengthening layer, wherein the strengthening layer is arranged between the toughness support layer and the protective layer; The material of the tough support layer includes a polyacrylate solidified material, which is formed by curing an acrylate resin with a first curing agent; the acrylate resin includes at least one of methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate and propylene acrylate; the first curing agent includes at least one of dibenzoyl peroxide, tert-butyl perbenzoate, phenol peroxide, acrylamide peroxide, diisopropylbenzene peroxide, maleic anhydride, acrylic anhydride, tributylamine and ethylenediamine.

2. The composite diaphragm according to claim 1, characterized in that: The sealing structure satisfies at least one of the following conditions: (1) The thickness of the toughness support layer is 1 mm to 3 mm; (2) The thickness of the protective layer is 1 mm to 5 mm; (3) The impact toughness value of the tough support layer is 50 J / m to 150 J / m.

3. The composite diaphragm according to claim 1, characterized in that: The material of the protective layer includes epoxy resin cured material, and the epoxy resin cured material is formed by curing epoxy resin with a second curing agent.

4. The composite diaphragm according to claim 3, characterized in that: The epoxy resin includes at least one of glycidyl ether epoxy resin, amino epoxy resin, glycidyl ester epoxy resin, epoxidized olefin resin, hydantoin epoxy resin, brominated epoxy resin and phosphated epoxy resin.

5. The composite diaphragm according to claim 3, characterized in that: The second curing agent includes at least one of an amine curing agent, an acid anhydride curing agent, a delayed curing agent and a composite curing agent.

6. The composite diaphragm according to any one of claims 1 to 5, characterized in that: The strengthening layer is in a porous mesh structure.

7. The composite diaphragm according to claim 6, characterized in that: The mesh number of the pore structure of the strengthening layer is 40-60 meshes.

8. The composite diaphragm according to claim 6, characterized in that: The material of the strengthening layer includes at least one of polyester, polyphenylene sulfide, polyurethane, polyacrylonitrile, polyetheretherketone and sulfonated polyetheretherketone.

9. The composite diaphragm according to claim 1, characterized in that: The edge of the diaphragm body is provided with a plurality of through holes penetrating the diaphragm body along the thickness direction; the sealing structure further comprises a support column, and the support column is arranged in the through hole.

10. The composite diaphragm according to claim 9, characterized in that: The through hole satisfies at least one of the following conditions: (1) The through holes are evenly opened along the edge of the diaphragm body; (2) The diameter of the through hole is 2 mm to 10 mm.

11. The composite diaphragm according to claim 1, characterized in that: The mesh support layer is at least partially exposed at the peripheries of the first porous layer and the second porous layer, and the exposed area of ​​the mesh support layer extends into the sealing structure.

12. A method for preparing the composite diaphragm according to any one of claims 1 to 11, characterized in that: The preparation method comprises: At the edge portion of the diaphragm body, a sealing material is used to cover at least a portion of the surface of both sides of the diaphragm body, and completely covers the side surfaces of the diaphragm body to form the sealing structure.

13. Use of the composite diaphragm according to any one of claims 1 to 11, characterized in that: The composite diaphragm is used for producing hydrogen by alkaline water electrolysis.

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