Anion exchange membrane and method for manufacturing the same

Abstract

According to an embodiment of the present application, an anion exchange membrane and a method for manufacturing the same can be provided, which contains a carbazolyl polymer but has reduced polymer cracking characteristics.

Description

Cross-reference to related applications

[0001] This application is based on and claims priority to Korean Patent Application No. 10-2023-0144082, filed on October 25, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to an anion exchange membrane and a method for manufacturing the same. Specifically, this invention relates to an anion exchange membrane comprising a carbazole-based polymer and a method for manufacturing the same. Background Technology

[0003] It emphasizes the importance of technologies that can produce and utilize hydrogen in an environmentally friendly manner, as hydrogen is a next-generation energy source that can address fossil fuel consumption and environmental pollution.

[0004] Anion exchange membrane fuel cells and membrane electrode assemblies (MEAs) for water electrolysis have a structure in which an anode electrode and a cathode electrode are laminated around an anion exchange membrane.

[0005] Specifically, the MEA used for water electrolysis includes anion exchange membrane, an anode electrode formed on one side of the anion exchange membrane, and a cathode electrode formed on the other side of the anion exchange membrane. A porous transport layer (PTL) and a membrane laminate are laminated at both ends of the MEA to form a unit stack. Multiple unit cells form a water electrolysis stack. Water decomposes at the cathode electrode to produce hydrogen and hydroxide ions, and oxygen is produced from hydroxide ions at the anode electrode. Each reaction occurs on the catalyst in the catalyst layer (CL). At this point, the anion exchange membrane (AEM) acts as a separator for the OH- ions generated at the cathode. - The function of ions moving to the anode electrode and preventing the movement of oxygen and hydrogen.

[0006] In particular, according to the hydrogen economy activation roadmap recently released by the South Korean Ministry of Trade, Industry and Energy, since most hydrogen production plans are carried out using environmentally friendly methods, there is an even greater need to develop water electrolysis, a representative technology for environmentally friendly hydrogen production.

[0007] In this regard, research is actively being conducted on water electrolysis technology using electrolysis methods. Therefore, proton exchange membrane water electrolysis (PEMWE), alkaline water electrolysis (AWE), and anion exchange membrane water electrolysis (AEMWE) are known as water electrolysis technologies.

[0008] Among them, anion exchange membrane water electrolysis is a water electrolysis system that can overcome the disadvantages of existing proton exchange membrane water electrolysis and alkaline water electrolysis while utilizing the advantages of existing proton exchange membrane water electrolysis and alkaline water electrolysis.

[0009] Carbazole-based polymers, intended for use as anion exchange materials in water electrolysis of this anion exchange membrane, are suitable as anion exchange materials due to their excellent alkali resistance and high conductivity. However, their cracking and brittle properties present challenges in practical applications. In particular, the repeated exposure to high temperatures and pressures during the manufacture of membrane electrode assemblies can lead to cracking or breakage of anion exchange membranes containing carbazole-based polymers. Summary of the Invention

[0010] [Technical Issues] Therefore, an anion exchange membrane and a method for manufacturing the same are provided, the anion exchange membrane comprising a carbazole-based polymer but having reduced polymer cracking properties.

[0011] [Technical Solution] An anion exchange membrane according to one embodiment of the present invention includes a first carbazole-based polymer layer; a porous support layer; and a second carbazole-based polymer layer, wherein the porous support layer is disposed between the first carbazole-based polymer layer and the second carbazole-based polymer layer, and the total thickness of the first carbazole-based polymer layer, the porous support layer and the second carbazole-based polymer layer can be greater than 40 μm and less than 150 μm.

[0012] The method may include: coating a first carbazole-based polymer composition onto a release sheet (step 1); placing a porous support on a layer of the first carbazole-based polymer composition to obtain a first composite film (step 2); drying the first composite film (step 3); coating a second carbazole-based polymer composition onto the porous support of the dried first composite film to obtain a second composite film (step 4); drying the second composite film (step 5); and removing the release sheet (step 6).

[0013] [Beneficial Effects] According to one embodiment of the present invention, an anion exchange membrane and a method thereof can be provided, the anion exchange membrane comprising a carbazole-based polymer but having reduced polymer cracking characteristics. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of an anion exchange membrane according to one embodiment of the present invention.

[0015] Figure 2 This is a scanning electron microscope (SEM) image of a cross-section of a 58 μm thick monolayer film of the comparative example of the present invention.

[0016] Figure 3 The image shows a cross-section of the 80.6 μm thick reinforcing film of the example, captured by scanning electron microscopy (SEM).

[0017] Figure 4 This is a photograph of a roll-type reinforced film manufactured according to the present invention.

[0018] Figure 5 This is a photograph confirming the brittleness of the anion exchange membrane manufactured in the experimental examples of this invention.

[0019] Figure 6 The results are evaluations of the water electrolysis system's performance after manufacturing an MEA with a reinforced composite membrane manufactured according to the present invention. Detailed Implementation

[0020] As used in this article, the terms “first,” “second,” etc., are used to describe various components, and these terms are only used to distinguish one component from other components.

[0021] Furthermore, the terminology used in this specification is for illustrative purposes only and is not intended to limit the invention. Singular expressions may include plural expressions unless the context differs. In this specification, the terms "comprising," "equipment," or "having" are used only to explain the features, quantities, steps, components, or combinations thereof that are in effect, and do not preclude the possibility of having or adding one or more different features, quantities, steps, components, or combinations thereof.

[0022] Furthermore, in this invention, when referring to layers or elements formed on or above some layers or elements, it means that each layer or element is formed directly on these layers or elements, or that other layers or elements may be formed between these layers, objects, or substrates.

[0023] This invention can be modified and has various forms, and specific embodiments will be described and detailed below. However, it should be understood that this description is not intended to limit the invention to the specific forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this invention.

[0024] Carbazole-based polymers are suitable as anion exchange membrane materials due to their excellent alkali resistance and high electrical conductivity. However, carbazole-based polymers have the disadvantage of being unsuitable for use as anion exchange membranes because of their cracking properties. In particular, anion exchange membranes containing carbazole-based polymers may crack or rupture during several high-temperature steps in the manufacturing process of membrane electrode assemblies.

[0025] Therefore, the inventors aim to provide an anion exchange membrane comprising a carbazole-based polymer but with improved cracking properties to take advantage of the excellent anion exchange properties of the carbazole-based polymer.

[0026] The anion exchange membrane comprising a carbazole-based polymer according to the present invention will be described in detail below.

[0027] An anion exchange membrane (100) according to one embodiment of the present invention may include a first carbazole-based polymer layer (1); a porous support layer (2); and a second carbazole-based polymer layer (3). Furthermore, the porous support layer may be disposed between the first carbazole-based polymer layer and the second carbazole-based polymer layer. That is, the anion exchange membrane of the present invention may be a composite membrane with a three-layer structure, wherein the carbazole-based polymer layer is coated on both sides of the porous support layer, and the porous support layer is located in the center.

[0028] The first carbazolyl polymer and the second carbazolyl polymer may each independently comprise a compound represented by the following chemical formula 1: [Chemical Formula 1]

[0029] In chemical formula 1, R1 to R4 are each independently C 1-60 Alkylene; C 6-60 Aromatic; or C 2-60 alkenyl, R1 through R4 can each be independently unsubstituted or substituted with one or more fluorine molecules. R1 through R4 can each independently contain one or more heteroatoms selected from the group consisting of O, N, and S to replace carbon. R1 through R4 can be the same or different for each repeating unit. X1 to X4 can each be an independent hydrogen atom; or an anion exchange group. One or more of X1 to X4 are anion exchange groups. The anion exchange group is selected from one or more groups chosen from the group consisting of amino, ammonium, amino, imino, sulfonyl, phosphonyl, pyridyl, carbazole, imidazole, or their salts, and m or n are each an independent integer from 1 to 100,000.

[0030] Specifically, the compound represented by Formula 1 can be poly(9-(6-(trimethylammonium bromide)hexyl)-9H-carbazole-co-1,1,1-trifluoroisopropane) represented by Formula 2.

[0031] [Chemical Formula 2]

[0032] The carbazole-based polymer contained in the first carbazole-based polymer layer and the carbazole-based polymer contained in the second carbazole-based polymer layer may be the same or different. Specifically, the carbazole-based polymer contained in the first carbazole-based polymer layer and the carbazole-based polymer contained in the second carbazole-based polymer layer may be the same polymer.

[0033] Porous supports may include one or more materials selected from the group consisting of polypropylene (PP), polyethylene (PE), and polytetrafluoroethylene (PTFE), each of which has excellent alkali resistance.

[0034] By using a porous material as a support, carbazole-based polymers are partially impregnated into the porous support to promote OH- - Ion transport, and the bonding of the first and second carbazole-based polymer layers to the porous support, can prevent the carbazole-based polymer from cracking.

[0035] In the anion exchange membrane, the total thickness of the first carbazole-based polymer layer, the porous support layer, and the second carbazole-based polymer layer can be greater than 40 μm and 170 μm or less. Specifically, the total thickness of the anion exchange membrane can be greater than 40 μm, and can be 60 μm or more, 70 μm or more, 80 μm or more, or 100 μm or more, and 170 μm or less, 150 μm or less, 140 μm or less, 130 μm or less, or 120 μm or less.

[0036] In anion water electrolysis systems, the range of hydrogen content relative to oxygen at the anode electrode is adjusted to prevent problems caused by explosions during system operation. The explosion range is designed so that an explosion is possible when the hydrogen content relative to oxygen is 4% or more, and the system shuts down when the hydrogen content reaches 2% or more.

[0037] Therefore, when the total thickness of the anion exchange membrane is 40 μm or less, the hydrogen generated at the cathode electrode moves through the anion exchange membrane to the anode electrode, resulting in a hydrogen content exceeding 2% relative to oxygen and a high probability that the system will not operate.

[0038] On the other hand, when the total thickness of the anion exchange membrane exceeds 170 μm, the carbazole polymer layer is thicker, and the properties of the carbazole polymer become dominant. Therefore, the manufactured anion exchange membrane may crack or break due to the cracking properties of the carbazole polymer.

[0039] Furthermore, the thickness of the first carbazole-based polymer layer can be from 5 μm to 73 μm. Specifically, the thickness can be from 15 μm to 70 μm.

[0040] Furthermore, the thickness of the porous support layer can range from 5 μm to 50 μm. Specifically, the thickness can range from 5 μm to 30 μm.

[0041] Furthermore, the thickness of the second carbazole-based polymer layer can be from 5 μm to 73 μm. Specifically, the thickness can be from 15 μm to 70 μm.

[0042] The composite membrane form of the anion exchange membrane of the present invention has improved cracking characteristics of carbazole-based polymers and can be processed into roll form (see...). Figure 5 ).

[0043] A method for manufacturing anion exchange membrane according to another embodiment of the present invention may include: The first carbazole-based polymer composition is coated onto the release sheet (step 1); a porous support is placed on the first carbazole-based polymer composition layer to obtain a first composite film (step 2); the first composite film is dried (step 3); a second carbazole-based polymer composition is coated onto the porous support of the dried first composite film to obtain a second composite film (step 4); the second composite film is dried (step 5); and the release sheet is removed (step 6).

[0044] Step 1 is the step of coating the first carbazole-based polymer composition onto the release sheet.

[0045] The first carbazole-based polymer composition may be a solution containing a carbazole-based polymer. There are no limitations on the solvent used in the solution, as long as it is a polar solvent, but it is preferable to include a polar aprotic solvent. For example, it may include N-methyl-2-pyrrolidone (NMP).

[0046] In addition, the first carbazole-based polymer composition may include a compound represented by the following chemical formula 1.

[0047] [Chemical Formula 1]

[0048] In chemical formula 1, R1 to R4 are each independently C 1-60 Alkylene; C 6-60 Aromatic; or C 2-60 alkenyl, R1 through R4 can each be independently unsubstituted or substituted with one or more fluorine molecules. R1 through R4 can each independently contain one or more heteroatoms selected from the group consisting of O, N, and S to replace carbon. R1 through R4 can be the same or different for each repeating unit. X1 to X4 can each be an independent hydrogen atom; or an anion exchange group. One or more of X1 to X4 are anion exchange groups. The anion exchange group is selected from one or more groups chosen from the group consisting of amino, ammonium, amino, imino, sulfonyl, phosphonyl, pyridyl, carbazole, imidazole, or their salts, and m or n are each an independent integer from 1 to 100,000.

[0049] Furthermore, there are no restrictions on the release sheet material, as long as it can be used in this field, but for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polyimide (PI) can be used.

[0050] Furthermore, there are no limitations on the method of coating the first carbazole-based polymer composition, as long as it is a general polymer coating method, but for example, comma coating, groove coating or gravure coating can be used.

[0051] Specifically, the compound represented by Formula 1 can be poly(9-(6-(trimethylammonium bromide)hexyl)-9H-carbazole-co-1,1,1-trifluoroisopropane) represented by Formula 2.

[0052] [Chemical Formula 2]

[0053] Step 2 is the step of obtaining the first composite film by positioning a porous support on the first carbazole-based polymer composition layer formed in step 1.

[0054] That is, the first composite membrane may have a structure in which a release sheet, a carbazole-based polymer composition layer and a porous support are sequentially laminated.

[0055] Porous supports may include one or more materials selected from the group consisting of polypropylene (PP), polyethylene (PE), and polytetrafluoroethylene (PTFE), each of which has excellent alkali resistance.

[0056] By using a porous material as a support, carbazole-based polymers are partially impregnated into the porous support to promote OH- - Ion transport and bonding of the first and second carbazole-based polymer layers to the porous support can prevent the carbazole-based polymer from cracking.

[0057] Step 3 is the step of drying the first composite membrane from step 2.

[0058] In step 3, the solvent in the first carbazole-based polymer composition layer included in the first composite membrane evaporates, and a portion of the first carbazole-based polymer can be dried while impregnated in a porous support.

[0059] The drying in step 3 can be carried out at a temperature between 40°C and 150°C. Specifically, the drying can be carried out at a temperature between 60°C and 80°C.

[0060] When the temperature is too low, the solvent takes too long to dry, which may result in it not drying before proceeding to step 4. Furthermore, when the carbazole-based polymer is impregnated into the porous support, the solution viscosity may increase and the impregnation rate may decrease. On the other hand, when the temperature is too high, the carbazole-based polymer may dry before impregnating the porous support, thus reducing the impregnation rate, or the support may shrink and wrinkle at high temperatures.

[0061] Step 4 is a step of obtaining the second composite membrane by coating the second carbazole-based polymer composition onto a porous support of the first composite membrane that is dried at high temperature.

[0062] The second carbazole polymer contained in the second carbazole polymer composition coated in step 4 may be the same as or different from the first carbazole polymer in step 1, and may include compounds represented by the following chemical formula 1.

[0063] [Chemical Formula 1]

[0064] In chemical formula 1, R1 to R4 are each independently C 1-60 Alkylene; C 6-60 Aromatic; or C 2-60 alkenyl, R1 through R4 can each be independently unsubstituted or substituted with one or more fluorine molecules. R1 through R4 can each independently contain one or more heteroatoms selected from the group consisting of O, N, and S to replace carbon. R1 through R4 can be the same or different for each repeating unit. X1 to X4 can each be an independent hydrogen atom; or an anion exchange group. One or more of X1 to X4 are anion exchange groups. The anion exchange group is selected from one or more groups chosen from the group consisting of amino, ammonium, amino, imino, sulfonyl, phosphonyl, pyridyl, carbazole, imidazole, or their salts, and m or n are each an independent integer from 1 to 100,000.

[0065] The second carbazole-based polymer composition coated in step 4 can also be a solution, and the solvent is not limited as long as it is a polar solvent, but preferably may include a polar aprotic solvent. For example, it may include N-methyl-2-pyrrolidone (NMP).

[0066] Furthermore, there are no limitations on the method for coating the second carbazole-based polymer composition in step 4, as long as it is a general polymer coating method. However, for example, comma coating, groove coating, or gravure coating can be used.

[0067] Specifically, the compound represented by Formula 1 can be poly(9-(6-(trimethylammonium bromide)hexyl)-9H-carbazole-co-1,1,1-trifluoroisopropane) represented by Formula 2.

[0068] [Chemical Formula 2]

[0069] Step 5 is the step of drying the second composite membrane obtained in step 4.

[0070] Since the second carbazole-based polymer composition coated in step 4 is in a solution state, it requires a drying step to be bonded to the porous support, similar to step 3. Therefore, the solvent in the second carbazole-based polymer composition layer coated in step 4 evaporates, and a portion of the carbazole-based polymer can be dried while immersed in the porous support.

[0071] The drying in step 5 can be carried out at a temperature between 40°C and 150°C. Specifically, the drying can be carried out at a temperature between 60°C and 80°C.

[0072] When the temperature is too low, there may still be undried parts even after the drying process. Therefore, there may be a problem of undried parts sticking to the release sheet when it is wound into rolls. When the temperature is too high, the shrinkage of the porous support due to heat may become severe, which may cause wrinkles.

[0073] Step 6 is the step of obtaining an anion exchange membrane having a structure in which a first carbazole-based polymer layer, a porous support, and a second carbazole-based polymer layer are sequentially laminated by removing the release sheet from step 1.

[0074] In an anion exchange membrane manufactured according to the method for manufacturing anion exchange membrane, the total thickness of the first carbazole-based polymer layer, the porous support layer, and the second carbazole-based polymer layer can be greater than 40 μm and less than 150 μm. Specifically, the total thickness of the anion exchange membrane manufactured according to the method for manufacturing anion exchange membrane can be greater than 40 μm, being 50 μm or more, 70 μm or more, or 100 μm or more, and less than 150 μm, being 140 μm or less, 130 μm or less, or 120 μm or less.

[0075] In anion water electrolysis systems, the range of hydrogen content relative to oxygen at the anode electrode is adjusted to prevent problems caused by explosions during system operation. The explosion range is designed such that an explosion is possible when the hydrogen content relative to oxygen is 4% or more, and the system shuts down when the hydrogen content reaches 2% or more.

[0076] Therefore, when the total thickness of the anion exchange membrane is 40 μm or less, the hydrogen generated at the cathode electrode moves through the anion exchange membrane to the anode electrode, resulting in a hydrogen content exceeding 2% relative to oxygen and a high probability that the system will not operate.

[0077] On the other hand, when the total thickness of the anion exchange membrane exceeds 150 μm, the carbazole polymer layer is thicker, and the properties of the carbazole polymer become dominant. Therefore, the manufactured anion exchange membrane may crack or break due to the cracking properties of the carbazole polymer.

[0078] In the following description, preferred exemplary embodiments are provided for a better understanding of the invention. However, the following exemplary embodiments are for illustrative purposes only, and the invention is not limited thereto.

[0079] Comparative Example 1 - Composite anion exchange membrane with a total thickness of 40 μm (Step 1) Using the polymer represented by the following chemical formula 2 as the first carbazole-based polymer and N-methyl-2-pyrrolidone (NMP) as a solvent, a first carbazole-based polymer composition with a solid content of 20 wt.% was prepared. A polyethylene naphthalate (PEN) film was prepared as a release sheet. The first carbazole-based polymer composition was coated onto one side of the release sheet using a comma coating method. At this time, the coating thickness of the first carbazole-based polymer composition was 100 μm.

[0080] The polymer represented by chemical formula 2 is poly(9-(6-(trimethylammonium bromide)hexyl)-9H-carbazole-co-1,1,1-trifluoroisopropane).

[0081] [Chemical Formula 2]

[0082] (Step 2) As a porous support, a polypropylene (PP) with a thickness of 12 μm is prepared and positioned on the first carbazole-based polymer composition layer to obtain the first composite film.

[0083] (Step 3) Dry the first composite film at 60°C for 20 minutes and at 80°C for 30 minutes to evaporate the solvent of the first carbazole-based polymer composition.

[0084] (Step 4) A second composite membrane is obtained by coating the second carbazole-based polymer composition onto a porous support of the dried first composite membrane. Here, the second carbazole-based polymer is a polymer represented by the following chemical formula 2, and N-methyl-2-pyrrolidone (NMP) is used as the solvent, with a solid content of 20 wt.%, and the coating is performed by a comma coating method with a coating thickness of 100 μm.

[0085] The polymer represented by chemical formula 2 is poly(9-(6-(trimethylammonium bromide)hexyl)-9H-carbazole-co-1,1,1-trifluoroisopropane).

[0086] [Chemical Formula 2]

[0087] (Steps 5 to 6) Dry the second composite membrane at 60°C for 20 minutes and at 80°C for 30 minutes, and remove the release sheet to obtain an anion exchange membrane with a thickness of 40 μm.

[0088] Comparative Example 2 - Monolayer anion exchange membrane with a total thickness of 50 μm (Step 1) Using the polymer represented by the above chemical formula 2 as the carbazole-based polymer and N-methyl-2-pyrrolidone (NMP) as the solvent, a carbazole-based polymer composition with a solid content of 20 wt.% was prepared. A polyethylene naphthalate (PEN) film was prepared as a release sheet. The first carbazole-based polymer composition was coated onto one side of the release sheet using a comma coating method. At this time, the coating thickness of the carbazole-based polymer composition was 250 μm.

[0089] (Step 2) Dry the carbazole-based membrane at 60°C for 20 minutes and at 80°C for 30 minutes to obtain a 50 μm anion exchange membrane.

[0090] Example 1 - Composite anion exchange membrane with a total thickness of 70 μm (Step 1) Using the polymer represented by the above chemical formula 2 as the first carbazole-based polymer and N-methyl-2-pyrrolidone (NMP) as a solvent, a first carbazole-based polymer composition with a solid content of 20 wt.% was prepared. A polyethylene naphthalate (PEN) film was prepared as a release sheet. The first carbazole-based polymer composition was coated onto one side of the release sheet using a comma coating method. At this time, the coating thickness of the first carbazole-based polymer composition was 180 μm.

[0091] (Step 2) As a porous support, a polypropylene (PP) with a thickness of 12 μm is prepared and positioned on the first carbazole-based polymer composition layer to obtain the first composite film.

[0092] (Step 3) Dry the first composite film at 60°C for 20 minutes and at 80°C for 30 minutes to evaporate the solvent of the first carbazole-based polymer composition.

[0093] (Step 4) A second composite membrane is obtained by coating the second carbazole-based polymer composition onto the porous support of the dried first composite membrane. Here, the second carbazole-based polymer is a polymer represented by the following chemical formula 2, and N-methyl-2-pyrrolidone (NMP) is used as the solvent, with a solid content of 20 wt.%, and the coating is performed by a comma coating method with a coating thickness of 180 μm.

[0094] (Steps 5 to 6) Dry the second composite membrane at 60°C for 20 minutes and at 80°C for 30 minutes, and remove the release sheet to obtain an anion exchange membrane with a thickness of 70 μm.

[0095] Example 2 - Composite anion exchange membrane with a total thickness of 150 μm (Step 1) Using the polymer represented by the above chemical formula 2 as the first carbazole-based polymer and N-methyl-2-pyrrolidone (NMP) as a solvent, a first carbazole-based polymer composition with a solid content of 20 wt.% was prepared. A polyethylene naphthalate (PEN) film was prepared as a release sheet. The first carbazole-based polymer composition was coated onto one side of the release sheet using a comma coating method. At this time, the coating thickness of the first carbazole-based polymer composition was 380 μm.

[0096] (Step 2) As a porous support, a polypropylene (PP) with a thickness of 12 μm is prepared and positioned on the first carbazole-based polymer composition layer to obtain the first composite film.

[0097] (Step 3) Dry the first composite film at 60°C for 20 minutes and at 80°C for 30 minutes to evaporate the solvent of the first carbazole-based polymer composition.

[0098] (Step 4) A second composite membrane is obtained by coating the second carbazole-based polymer composition onto the porous support of the dried first composite membrane. Here, the second carbazole-based polymer is similarly used as the polymer represented by chemical formula 2, and N-methyl-2-pyrrolidone (NMP) is used as the solvent, with a solid content of 20 wt.%, and the coating is performed by a comma coating method, with a coating thickness of 380 μm.

[0099] (Steps 5 to 6) Dry the second composite membrane at 60°C for 20 minutes and at 80°C for 30 minutes, and remove the release sheet to obtain an anion exchange membrane with a thickness of 150 μm.

[0100] Example 3 - Composite anion exchange membrane with a total thickness of 170 μm (Step 1) Using the polymer represented by the above chemical formula 2 as the first carbazole-based polymer and N-methyl-2-pyrrolidone (NMP) as a solvent, a first carbazole-based polymer composition with a solid content of 20 wt.% was prepared. A polyethylene naphthalate (PEN) film was prepared as a release sheet. The first carbazole-based polymer composition was coated onto one side of the release sheet using a comma coating method. At this time, the coating thickness of the first carbazole-based polymer composition was 420 μm.

[0101] (Step 2) As a porous support, a polypropylene (PP) with a thickness of 12 μm is prepared and positioned on the first carbazole-based polymer composition layer to obtain the first composite film.

[0102] (Step 3) Dry the first composite film at 60°C for 20 minutes and at 80°C for 30 minutes to evaporate the solvent of the first carbazole-based polymer composition.

[0103] (Step 4) A second composite membrane is obtained by coating the second carbazole-based polymer composition onto the porous support of the dried first composite membrane. Here, the second carbazole-based polymer is similarly used as the polymer represented by chemical formula 2, and N-methyl-2-pyrrolidone (NMP) is used as the solvent, with a solid content of 20 wt.%, and the coating is performed by a comma coating method, with a coating thickness of 420 μm.

[0104] (Steps 5 to 6) Dry the second composite membrane at 60°C for 20 minutes and at 80°C for 30 minutes, and remove the release sheet to obtain an anion exchange membrane with a thickness of 170 μm.

[0105] Example 4 - Composite anion exchange membrane with a total thickness of 60 μm (Step 1) Using the polymer represented by the above chemical formula 2 as the first carbazole-based polymer and N-methyl-2-pyrrolidone (NMP) as a solvent, a first carbazole-based polymer composition with a solid content of 20 wt.% was prepared. A polyethylene naphthalate (PEN) film was prepared as a release sheet. The first carbazole-based polymer composition was coated onto one side of the release sheet using a comma coating method. At this time, the coating thickness of the first carbazole-based polymer composition was 150 μm.

[0106] (Step 2) As a porous support, a polypropylene (PP) with a thickness of 12 μm is prepared and positioned on the first carbazole-based polymer composition layer to obtain the first composite film.

[0107] (Step 3) Dry the first composite film at 60°C for 20 minutes and at 80°C for 30 minutes to evaporate the solvent of the first carbazole-based polymer composition.

[0108] (Step 4) A second composite membrane is obtained by coating the second carbazole-based polymer composition onto the porous support of the dried first composite membrane. Here, the second carbazole-based polymer is similarly used as the polymer represented by chemical formula 2, and N-methyl-2-pyrrolidone (NMP) is used as the solvent, with a solid content of 20 wt.%, and the coating is performed by a comma coating method with a coating thickness of 150 μm.

[0109] (Steps 5 to 6) Dry the second composite membrane at 60°C for 20 minutes and at 80°C for 30 minutes, and remove the release sheet to obtain an anion exchange membrane with a thickness of 60 μm.

[0110] Example 5 - Composite anion exchange membrane with a total thickness of 80 μm (Step 1) Using the polymer represented by the above chemical formula 2 as the first carbazole-based polymer and N-methyl-2-pyrrolidone (NMP) as a solvent, a first carbazole-based polymer composition with a solid content of 20 wt.% was prepared. A polyethylene naphthalate (PEN) film was prepared as a release sheet. The first carbazole-based polymer composition was coated onto one side of the release sheet using a comma coating method. At this time, the coating thickness of the first carbazole-based polymer composition was 200 μm.

[0111] (Step 2) As a porous support, a polypropylene (PP) with a thickness of 12 μm is prepared and positioned on the first carbazole-based polymer composition layer to obtain the first composite film.

[0112] (Step 3) Dry the first composite film at 60°C for 20 minutes and at 80°C for 30 minutes to evaporate the solvent of the first carbazole-based polymer composition.

[0113] (Step 4) A second composite membrane is obtained by coating the second carbazole-based polymer composition onto the porous support of the dried first composite membrane. Here, the second carbazole-based polymer is similarly used as the polymer represented by chemical formula 2, and N-methyl-2-pyrrolidone (NMP) is used as the solvent, with a solid content of 20 wt.%, and the coating is performed by a comma coating method with a coating thickness of 200 μm.

[0114] (Steps 5 to 6) Dry the second composite membrane at 60°C for 20 minutes and at 80°C for 30 minutes, and remove the release sheet to obtain an anion exchange membrane with a thickness of 80 μm.

[0115] Experimental Example 1 - Evaluation of Hydrogen Permeability The hydrogen content at the anode electrode relative to the amount of oxygen was measured using the anion exchange membranes manufactured in Comparative Example 1 and Examples 4 and 5, as shown in the table below.

[0116] Table 1

[0117] Hydrogen generated at the cathode moves to the anode electrode through the reinforcing film. As the thickness of the reinforcing film increases, the amount of hydrogen moving decreases.

[0118] There is a possibility of explosion when the hydrogen content relative to oxygen is 4% or more, and according to safety regulations, the system is designed to shut down when the hydrogen content relative to oxygen is 2% or more. That is, the hydrogen content relative to oxygen at the anode must be less than 2%.

[0119] In this experimental example, the hydrogen content relative to oxygen at the anode electrode was measured during operation of the anion exchange membrane water electrolysis system at atmospheric pressure at 1.5 A / cm². 2 Measurements were performed. Hydrogen content was measured using a gas chromatograph (GC) from Agilent. The hydrogen content relative to oxygen was 2.0% when the reinforced membrane thickness was 40 µm, 1.7% when the reinforced membrane thickness was 60 µm, and 1.4% when the reinforced membrane thickness was 80 µm.

[0120] Experiment Example 2 - SEM Observation The cross-sections of the anion exchange membranes manufactured in Comparative Example 2 and Example 5 were observed by SEM, as shown below. Figure 3 and Figure 4 As shown.

[0121] Experimental Example 3 - Crack Observation The presence or absence of cracking was confirmed by physically folding the anion exchange membranes manufactured in Examples 2 and 3, as well as Comparative Example 2. Figure 6 As shown.

[0122] Regarding brittleness, cut the reinforcing membrane into 10mm x 50mm pieces, hold and bend the corners of the shorter sections, and then press the bent center section firmly to check for cracking.

[0123] Comparative Example 2 was a single-layer anion exchange membrane, not a composite membrane with a central reinforcing layer. Therefore, when confirming whether cracking had occurred, it was confirmed that the exchange membrane was completely cut and cracked. In Example 2, it was confirmed that the anion exchange membrane did not crack even when fully bent and pressed at the center. In Example 3, some cracking was confirmed, but the anion exchange membrane did not completely crack and separate.

[0124] Experimental Example 4 - Confirmation of Water Electrolysis Performance The water electrolysis performance of Comparative Example 1 and Examples 4 and 5 was evaluated. The performance was evaluated at a battery temperature of 60°C using a 1 mol KOH solution.

[0125] The result of comparing Comparative Example 1 with Examples 4 and 5 is that, in the case of the example with the addition of a porous support layer, the total thickness increases, and therefore the voltage is slightly higher than that of the comparative example at the same amount of hydrogen production, but it looks slightly different.

[0126] Therefore, it was confirmed that the porous support layer improved the crack-related properties without reducing the water electrolysis performance.

[0127] [Symbol Explanation] 100: Anion exchange membrane 1: First carbazole polymer layer 2: Porous support layer; 3: Second carbazole polymer layer

Claims

1. An anion exchange membrane, comprising a first carbazole-based polymer layer; a porous support layer; and a second carbazole-based polymer layer. in, The porous support layer is disposed between the first carbazole-based polymer layer and the second carbazole-based polymer layer, and The total thickness of the first carbazole-based polymer layer, the porous support layer, and the second carbazole-based polymer layer is greater than 40 μm and is 170 μm or less.

2. The anion exchange membrane according to claim 1, in, The porous support comprises one or more selected from the group consisting of polypropylene (PP), polyethylene (PE), and polytetrafluoroethylene (PTFE).

3. The anion exchange membrane according to claim 1, in, The first carbazole-based polymer and the second carbazole-based polymer each independently comprise a compound represented by the following chemical formula 1: [Chemical Formula 1] In chemical formula 1, R1 to R4 are each independently C 1-60 Alkylene; C 6-60 Aromatic; or C 2-60 alkenyl, R1 through R4 can each be independently unsubstituted or substituted with one or more fluorine molecules. R1 through R4 can each independently contain one or more heteroatoms selected from the group consisting of O, N, and S to replace carbon. R1 through R4 can be the same or different for each repeating unit. X1 to X4 can each be an independent hydrogen atom; or an anion exchange group. One or more of X1 to X4 are anion exchange groups. The anion exchange group is selected from one or more groups chosen from the group consisting of amino, ammonium, amino, imino, sulfonyl, phosphonyl, pyridyl, carbazole, imidazole, or their salts, and m or n are each an independent integer from 1 to 100,000.

4. The anion exchange membrane according to claim 1, in, The thickness of the first carbazole-based polymer layer is 5 μm to 73 μm.

5. The anion exchange membrane according to claim 1, in, The thickness of the second carbazole-based polymer layer is 5 μm to 73 μm.

6. The anion exchange membrane according to claim 1, in, The thickness of the porous support layer is 5 μm to 50 μm.

7. A method for manufacturing anion exchange membranes, comprising: The first carbazole-based polymer composition is coated onto the release sheet (step 1). A porous support is placed on a layer of the first carbazole-based polymer composition to obtain a first composite film (step 2). Dry the first composite membrane (step 3); The second carbazole-based polymer composition is coated onto the dry porous support of the first composite membrane to obtain the second composite membrane (step 4). Dry the second composite membrane (step 5); and Remove the release sheet (step 6).

8. The method for manufacturing anion exchange membrane according to claim 7, in, Step 3 is performed at a temperature between 40°C and 150°C.

9. The method for manufacturing anion exchange membrane according to claim 7, in, In the anion exchange membrane, the total thickness of the first carbazole polymer layer, the porous support layer, and the second carbazole polymer layer is greater than 40 μm and is 170 μm or less.

10. The method for manufacturing anion exchange membrane according to claim 7, in, The porous support comprises one or more selected from the group consisting of polypropylene (PP), polyethylene (PE), and polytetrafluoroethylene (PTFE).

11. The method for manufacturing anion exchange membrane according to claim 7, in, The first carbazole-based polymer composition and the second carbazole-based polymer composition each independently comprise a compound represented by the following chemical formula 1: [Chemical Formula 1] In chemical formula 1, R1 to R4 are each independently C 1-60 Alkylene; C 6-60 Aromatic; or C 2-60 alkenyl, R1 through R4 can each be independently unsubstituted or substituted with one or more fluorine molecules. R1 through R4 can each independently contain one or more heteroatoms selected from the group consisting of O, N, and S to replace carbon. R1 through R4 can be the same or different for each repeating unit. X1 to X4 can each be an independent hydrogen atom; or an anion exchange group. One or more of X1 to X4 are anion exchange groups. The anion exchange group is selected from one or more groups chosen from the group consisting of amino, ammonium, amino, imino, sulfonyl, phosphonyl, pyridyl, carbazole, imidazole, or their salts, and m or n are each an independent integer from 1 to 100,000.

12. A membrane electrode assembly for a fuel cell, the membrane electrode assembly comprising an anion exchange membrane according to any one of claims 1 to 6.

13. A membrane electrode assembly for water electrolysis, the membrane electrode assembly comprising an anion exchange membrane according to any one of claims 1 to 6.

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