Electrolyte membrane for patterned membrane electrode assembly and method of making same

Abstract

The invention provides an electrolyte membrane for a patterned membrane electrode assembly and a preparation method thereof. The hydrocarbon ion exchange membrane is hydrated and then compressed by a grid template, and an embedded pattern is formed on the surface of the hydrocarbon ion exchange membrane. And after dehydration, removing the template to obtain the electrolyte membrane with higher water absorption, ionic conductivity and mechanical property. The method supports large area production at a temperature of about 70 DEG C to 90 DEG C and a pressure of about 5 MPa to 15 MPa. The catalyst slurry may be coated onto the patterned membrane to form a membrane electrode assembly, thereby enhancing bond strength and catalyst utilization in electrochemical devices such as fuel cells and water electrolysers. The resulting film has a moisture content of about 60% by weight or more, a Young's modulus of about 100 MPa or less, and a pattern depth of about 40% or more relative to template lines.

Description

Technical Field

[0001] This invention relates to a method for preparing an electrolyte membrane for patterned membrane electrode assemblies by utilizing the functional properties of hydrocarbon-based ion exchange membranes. Background Technology

[0002] Numerous studies have reported on the application of ion exchange membrane surface patterning technology to electrochemical devices such as fuel cells and water electrolysis devices. By modifying the structure of ion exchange membranes through patterning, the migration of water and hydrogen ions in locally thinned sections within the membrane can be promoted. Furthermore, the interface between the ion exchange membrane and the electrode can be widened, thereby improving catalyst utilization and enhancing the bonding force between the membrane and the electrode to improve durability.

[0003] Because fluorine-based ion exchange membranes, such as Nafion, have a low glass transition temperature of about 100°C, they can be easily patterned using hot embossing techniques.

[0004] However, due to the high glass transition temperature (approximately 200°C) of hydrocarbon-based ion exchange membranes, the application of thermoimprinting requires temperatures reaching or exceeding this glass transition temperature, which can damage the membrane's main and side chains. Therefore, techniques for patterning hydrocarbon-based ion exchange membranes have been routinely reported using: 1) methods involving casting an ionomer solution (not in ion exchange membrane form) onto a patterned substrate and allowing it to dry; 2) methods involving coating nanoparticles onto a substrate together with an ionomer solution, followed by nanoparticle removal to form a three-dimensional structure; and 3) methods such as physical and / or chemical etching using plasma and masks. However, methods using ionomer solutions are difficult to produce large-area ion exchange membranes, hindering the commercialization of ion exchange membranes. Methods using nanoparticles require post-processing to remove the nanoparticles, resulting in high production costs. Physical and / or chemical etching can lead to degradation of the ion exchange membrane due to plasma irradiation. Summary of the Invention

[0005] One object of the present invention is to provide an electrolyte membrane for patterned membrane electrode assemblies that is advantageous for large-area production and a method for preparing the same.

[0006] Another object of the present invention is to provide a method for preparing an electrolyte membrane that can be patterned without affecting its mechanical and electrochemical properties.

[0007] Another object of the present invention is to provide an electrolyte membrane for patterned membrane electrode assemblies that is conducive to large-scale production and a method for preparing the same.

[0008] The objectives of this invention are not limited to those described above. The objectives of this invention will become more apparent from the following description and will be achieved by the means and combinations thereof described in the claims.

[0009] On one hand, a method for preparing an electrolyte membrane for a membrane electrode assembly is provided, the method comprising the steps of: a) obtaining a first intermediate by hydrating a hydrocarbon-based ion exchange membrane; b) obtaining a second intermediate by stacking a template on at least one surface of the first intermediate and applying pressure in the stacking direction; c) obtaining an electrolyte membrane by dehydrating the second intermediate and removing the template from the second intermediate, wherein the electrolyte membrane includes a pattern with a shape corresponding to the template.

[0010] On the other hand, a method for preparing an electrolyte membrane for a membrane electrode assembly according to an embodiment of the present invention may include the following steps: obtaining a first intermediate by hydrating (absorbing water) a hydrocarbon-based ion exchange membrane; obtaining a second intermediate by stacking a template having a predetermined shape on at least one surface of the first intermediate and applying pressure in the stacking direction; and obtaining an electrolyte membrane by dehydrating the second intermediate and removing the template from the second intermediate.

[0011] A pattern whose shape corresponds to that of the template can be formed and embedded in at least one surface of the electrolyte membrane.

[0012] The step of obtaining the first intermediate may be to soak a hydrocarbon-based ion exchange membrane in a solvent at 70°C to 90°C for 4 to 6 hours.

[0013] The first intermediate obtained by immersing a hydrocarbon-based ion exchange membrane in a solvent at 80°C for 4 hours can have a water content of 60% by weight or higher.

[0014] When hydrocarbon-based ion exchange membranes are immersed in a solvent at 80°C for 4 hours, the length change rate of the hydrocarbon-based ion exchange membranes can be 10% or higher.

[0015] When hydrocarbon-based ion exchange membranes are immersed in a solvent at 80°C for 4 hours, the thickness change rate of the hydrocarbon-based ion exchange membranes can be 30% or higher.

[0016] The Young's modulus of the first intermediate obtained by immersing a hydrocarbon-based ion exchange membrane in a solvent at 80°C for 4 hours can be 100 MPa or lower.

[0017] The template can be a grid shape, in which lines intertwine in a mesh pattern.

[0018] The stiffness of the template can be higher than that of the first intermediate body.

[0019] The template can be made of stainless steel.

[0020] The template width can be 300 mm or greater, the length can be 500 mm or greater, and the size of the first intermediate body can be equal to or greater than the size of the template.

[0021] The template width can be 300 mm or greater, the length can be 500 mm or greater, and the size of the first intermediate body can be equal to or smaller than the size of the template.

[0022] The step of obtaining the second intermediate may be to stack a template on at least one surface of the first intermediate and apply a pressure of 5 MPa to 15 MPa in the stacking direction at a temperature of 70°C to 90°C.

[0023] The steps to obtain the electrolyte membrane may be to dehydrate the second intermediate by compressing it at a temperature of 70°C to 90°C for 1 to 2 hours and then removing the template.

[0024] A method for manufacturing a membrane electrode assembly according to one embodiment of the present invention may include the step of coating a catalyst slurry onto two surfaces of an electrolyte membrane to manufacture a pair of electrodes, wherein the electrodes may fill spaces formed to be embedded in the electrolyte membrane.

[0025] An electrolyte membrane for a membrane electrode assembly according to one embodiment of the present invention may include a hydrocarbon-based ion exchange membrane, wherein the hydrocarbon-based ion exchange membrane may have a pattern corresponding to a template pattern formed to be embedded in at least one of its surfaces, and the template may have a grid shape, wherein lines are intertwined in a mesh shape.

[0026] When a hydrocarbon-based ion exchange membrane is immersed in a solvent at 80°C for 4 hours, the water content of the hydrocarbon-based ion exchange membrane can be 60% by weight or higher.

[0027] When a hydrocarbon-based ion exchange membrane is immersed in a solvent at 80°C for 4 hours, the longitudinal change rate of the hydrocarbon-based ion exchange membrane can be 10% or higher.

[0028] When a hydrocarbon-based ion exchange membrane is immersed in a solvent at 80°C for 4 hours, the width-direction change rate of the hydrocarbon-based ion exchange membrane can be 30% or higher.

[0029] When a hydrocarbon-based ion exchange membrane is immersed in a solvent at 80°C for 4 hours, the Young's modulus of the hydrocarbon-based ion exchange membrane can be 100 MPa or lower.

[0030] The depth of the pattern formed embedded in the hydrocarbon-based ion exchange membrane can be 40% or more of the cross-sectional diameter of the template lines.

[0031] According to the present invention, an electrolyte membrane for patterned membrane electrode assemblies that is advantageous for large-area production can be obtained, as well as a method for preparing the same.

[0032] According to the present invention, electrolyte membranes can be patterned without affecting mechanical and electrochemical properties.

[0033] According to the present invention, an electrolyte membrane for patterned membrane electrode assemblies that is conducive to large-scale production can be obtained, as well as a method for preparing the same.

[0034] According to the present invention, by patterning the ion exchange membrane using the functional properties of the ion exchange membrane, an electrolyte membrane for membrane electrode assemblies that is environmentally friendly and harmless to the human body can be obtained, as well as a method for preparing the same.

[0035] According to the present invention, an electrolyte membrane for membrane electrode assemblies in which water and hydrogen ions migrate smoothly is obtained, and a method thereof is also provided for its preparation.

[0036] According to the present invention, an electrolyte membrane for membrane electrode assemblies with excellent bonding between the ion exchange membrane and the electrode, and a method thereof are provided for its preparation.

[0037] According to the present invention, an electrolyte membrane for membrane electrode assemblies with high catalyst utilization due to having a wide interface between the ion exchange membrane and the electrode is obtained, as well as a method for preparing the same.

[0038] As described above, the method and system appropriately include the use of a controller or processor.

[0039] The effects of this invention are not limited to those described above. It should be understood that the effects of this invention include all effects that can be inferred from the following description. Attached Figure Description

[0040] Figure 1 A membrane electrode assembly according to the present invention is shown.

[0041] Figure 2 This describes the steps involved in obtaining the first intermediate.

[0042] Figure 3 This describes the steps for obtaining the second intermediate.

[0043] Figure 4 This is used to illustrate the steps for obtaining an electrolyte membrane.

[0044] Figure 5 This describes a method for manufacturing a membrane electrode assembly according to the present invention.

[0045] Figure 6This is an enlarged cross-sectional view of the membrane electrode assembly according to the present invention.

[0046] Figure 7 The length change rate, thickness change rate, and water content of the first intermediate according to preparation example 1-1, comparative preparation example 1-1, and comparative preparation example 2-1 are shown.

[0047] Figure 8 The tensile strength of the first intermediates according to Preparation Example 1-1, Comparative Preparation Example 1-1, and Comparative Preparation Example 2-1 is shown.

[0048] Figure 9 To prepare the template used in Examples 1-2.

[0049] Figure 10 for Figure 9 Optical image of the template.

[0050] Figure 11 for Figure 9 Laser outline image of the template.

[0051] Figure 12 Optical images and laser profile images of the electrolyte membranes prepared in Examples 1-2 are presented for comparison.

[0052] Figure 13 Optical and laser profile images of the electrolyte membrane prepared in Comparative Example 2-2 are provided.

[0053] Figure 14 Optical images and laser profile images of the electrolyte membranes prepared according to Examples 1-2.

[0054] Figure 15 Images are shown to illustrate the results of scanning electron microscopy analysis of the surface and cross-section of the electrolyte membranes prepared according to Comparative Examples 1-2.

[0055] Figure 16 Images are shown to illustrate the results of analysis of the surface and cross-section of the electrolyte membrane prepared according to Comparative Example 2-2 using scanning electron microscopy.

[0056] Figure 17 Images are shown to illustrate the results of analyzing the surface and cross-section of the electrolyte membranes prepared according to Examples 1-2 using scanning electron microscopy.

[0057] Figure 18 Images showing the results of analyzing the surface and cross-section of the membrane electrode assembly according to the comparative example using scanning electron microscopy.

[0058] Figure 19 Images showing the results of analyzing the surface and cross-section of the membrane electrode assembly according to an embodiment using scanning electron microscopy.

[0059] Figure 20A graph showing the adhesion strength measurement results of the membrane electrode assembly according to the embodiments and comparative examples. Detailed Implementation

[0060] The above-mentioned objects, other objects, features, and advantages of the present invention will be more readily understood through the following preferred embodiments related to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be implemented in other forms. Rather, the embodiments described herein are provided so that the disclosure can be comprehensive and complete, and can fully convey the spirit of the invention to those skilled in the art.

[0061] In interpreting each drawing, similar reference numerals are used for similar elements. For clarity of the invention, the structural dimensions in the drawings have been enlarged from actual dimensions. Terms such as first, second, etc., may be used to describe various components, but components should not be limited by these terms. These terms are used only for the purpose of distinguishing one component from another. For example, a first component may be referred to as a second component without departing from the scope of the invention, and similarly, a second component may be referred to as a first component. Unless the context clearly specifies otherwise, singular expressions also include plural expressions.

[0062] In this specification, the terms "comprising," "having," etc., are intended to indicate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification. However, it should be understood that these terms do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Furthermore, when a portion of a layer, membrane, region, plate, etc., is referred to as being "above" another portion, this includes not only the case where it is "directly above" the other portion, but also the case where other portions exist between them. Conversely, when a portion of a layer, membrane, region, plate, etc., is referred to as being "below" another portion, this includes not only the case where it is "directly below" the other portion, but also the case where other portions exist between them.

[0063] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are also intended to include the plural forms. These terms are intended only to distinguish one component from another, and the terms do not limit the nature, order, or sequence of the constituent components. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Furthermore, the terms “unit,” “device,” “machine,” and “module” described in this specification refer to a unit for performing at least one function and operation, and can be implemented by hardware components or software components and combinations thereof.

[0064] Although exemplary embodiments are described as using multiple units to perform exemplary processes, it is understood that exemplary processes can also be performed by one or more modules. Furthermore, it is understood that the term "controller / control unit" refers to a hardware device that includes a memory and a processor and is specifically programmed to perform the processes described herein. The memory is configured to store modules, and the processor is specifically configured to execute the modules to perform one or more processes further described below.

[0065] Furthermore, the control logic of the present invention can be implemented as a non-transitory computer-readable medium containing executable program instructions that are executed by a processor, controller, etc. Examples of computer-readable media include, but are not limited to, ROM, RAM, optical disc (CD)-ROM, magnetic tape, floppy disk, flash drive, smart card, and optical data storage device. The computer-readable medium can also be distributed across a network-connected computer system so that it can be stored and executed in a distributed manner, for example, via a telematics server or a controller area network (CAN).

[0066] Unless otherwise stated, all figures, numerical values, and / or expressions used in this specification to represent the amounts of components, reaction conditions, polymer compositions, and formulations are approximate values, reflecting various measurement uncertainties that arise when obtaining these values. These figures are inherently different and should therefore be understood in all cases to be modified by the term "about". Furthermore, when a numerical range is disclosed in this specification, unless otherwise stated, the range is continuous and includes all values ​​from the minimum to the maximum (inclusive) of the range. Additionally, when the range refers to integers, unless otherwise stated, it includes all integers from the minimum to the maximum (inclusive).

[0067] Unless otherwise stated or the context clearly indicates, the term "about" as used herein should be understood to mean within the normal tolerance range in the field, such as within two standard deviations of the mean. "About" can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the specified value. Unless the context clearly indicates otherwise, all numerical values ​​provided herein are modified by the term "about".

[0068] Figure 1 A membrane electrode assembly according to the present invention is shown. The membrane electrode assembly can be used in electrochemical devices such as fuel cells, water electrolysis cells, etc. The membrane electrode assembly may include an electrolyte membrane 10 and electrodes 20 and 20' located on the electrolyte membrane 10. When electrode 20 located on one surface of the electrolyte membrane 10 is a cathode, electrode 20' located on the other surface may be an anode.

[0069] The method for preparing an electrolyte membrane 10 for a membrane electrode assembly according to the present invention may include the following steps: obtaining a first intermediate by hydrating (absorbing water) a hydrocarbon-based ion exchange membrane; obtaining a second intermediate by stacking a template having a predetermined shape on at least one surface of the first intermediate and applying pressure in the stacking direction; and obtaining an electrolyte membrane by dehydrating the second intermediate and removing the template from the second intermediate.

[0070] In some implementations, the term "predetermined shape" refers to any intentionally formed geometry or pattern that a template is designed to imprint onto a hydrocarbon-based ion exchange membrane. This shape can be a grid pattern, a lattice, or any other structural arrangement, intended to impart a corresponding embedded pattern to the membrane surface under pressure. The shape is "predetermined" because it is determined before contact with the membrane (e.g., by fabricating or selecting a template with a specific geometry) and remains consistent throughout the imprinting process.

[0071] Figure 2 This describes the steps involved in obtaining the first intermediate. (Reference) Figure 2 The first intermediate 200 can be obtained by hydrating the hydrocarbon-based ion exchange membrane 100.

[0072] The type of hydrocarbon-based ion exchange membrane 100 is not particularly limited and may include, for example, polyethersulfone, cross-linked polystyrene sulfonic acid, polyacrylic acid, polyvinyl sulfonic acid, poly(2-acrylamide-2-methylpropyl sulfonic acid), sulfonated polyimide, sulfonated polysulfone, sulfonated alkylated polysulfone, sulfonated polycarbonate, poly(p-phenylene) substituted with sulfonated phenoxybenzyl, sulfonated polyquinoxaline, sulfonated (phosphonic) polyphosphazene, sulfonated polyketone, sulfonated poly(phenylene oxides) (poly(phenylene oxides)), polybenzimidazole, sulfonated polyethersulfone, sulfonated polyether ketone, sulfonated polyphenylene sulfide, sulfonated polyphenylene sulfone, sulfonated polyphenylene sulfone nitrile, sulfonated polysulfide ketone, sulfonated polyarylene ether, sulfonated polyarylene ether nitrile, sulfonated polyarylene ether nitrile, sulfonated polyarylene ether sulfone ketone and sulfonated polyarylene ether sulfone.

[0073] In some embodiments, the term "hydrocarbon-based ion exchange membrane" refers to any ion exchange membrane whose polymer backbone is primarily (e.g., at least 50%, 60%, 70%, 80%, 90%, etc.) composed of hydrocarbon units (e.g., aromatic or aliphatic hydrocarbon structures) rather than fluorocarbon units. Examples include, but are not limited to, polyethersulfone, cross-linked polystyrene sulfonic acid, sulfonated polysulfone, sulfonated polyimide, sulfonated poly(phenylene ether), sulfonated polyether ether ketone (sPEEK), or combinations thereof. Such membranes typically differ from fluorinated membranes (e.g., Nafion) because they generally have a higher glass transition temperature (about 200°C or higher) and do not contain a fluorinated backbone. In some embodiments, the ion exchange capacity (IEC) of the hydrocarbon-based ion exchange membrane is at least about 2.0 meq / g to achieve adequate hydration (water absorption).

[0074] Typically, hydrocarbon-based ion exchange membranes 100, with an ion exchange capacity (IEC) of 2.0 meq / g or higher, are widely used due to their high hydrogen ion conductivity, thus enabling them to absorb large quantities of water. For example... Figure 2 As shown, as the hydrocarbon-based ion exchange membrane 100 absorbs water, its volume expands and it may become plasticized. Here, plasticization can refer to the hydrocarbon-based ion exchange membrane 100 becoming softer and easier to flow.

[0075] Specifically, a hydrocarbon-based ion exchange membrane 100 can be immersed in a solvent at 70°C to 90°C for 4 to 6 hours to obtain a first intermediate 200. If the immersion temperature is below 70°C, the dimensional change rate of the hydrocarbon-based ion exchange membrane 100 is low, and the Young's modulus is not sufficiently reduced, thus potentially preventing proper patterning using a template as described later. The solvent may include water. In some embodiments, the term "solvent" refers to any liquid or liquid mixture in which the hydrocarbon-based ion exchange membrane can be immersed or contacted for hydration (water absorption) and plasticization. In some embodiments, water is the primary solvent used for hydrating the membrane. However, other solvents (including aqueous mixtures or other co-solvents) may also be used, provided they enable the membrane to absorb sufficient water, thereby achieving dimensional changes and reducing mechanical stiffness, which facilitates patterning.

[0076] The first intermediate 200, obtained by immersing a hydrocarbon-based ion exchange membrane 100 in a solvent at approximately 80°C for about 4 hours, may have a water content of 60% by weight or higher. Water content can refer to the percentage of solvent mass to the total mass of the first intermediate 200. The water content of the first intermediate 200 can be calculated by measuring the mass of the first intermediate 200 and the mass of the hydrocarbon-based ion exchange membrane 100. There is no particular upper limit to the water content; for example, it may be 80% by weight or lower, 75% by weight or lower, or 70% by weight or lower.

[0077] When the water content of the first intermediate 200 is 60% by weight or higher, the hydrocarbon-based ion exchange membrane 100 has a high rate of dimensional change, thus providing sufficient space for patterning in the electrolyte membrane 10.

[0078] When the hydrocarbon-based ion exchange membrane 100 is immersed in a solvent at approximately 80°C for about 4 hours, the length change rate of the hydrocarbon-based ion exchange membrane 100 can be 10% or higher, and the thickness change rate can be 30% or higher. There is no particular upper limit to the length change rate; for example, it can be 20% or lower. There is also no particular upper limit to the thickness change rate; for example, it can be 50% or lower. The hydrocarbon-based ion exchange membrane 100 can be a sheet composed of a long side and a short side, where the long side can be referred to as the length L and the short side as the width W. (Reference) Figure 2 The length change rate can refer to the difference between the length L of the hydrocarbon-based ion exchange membrane 100 before immersion and the length L' of the first intermediate 200 after immersion. The thickness change rate can refer to the difference between the thickness T of the hydrocarbon-based ion exchange membrane 100 before immersion and the thickness T' of the first intermediate 200 after immersion.

[0079] The length L of the hydrocarbon-based ion exchange membrane 100 is not particularly limited, and can be, for example, 500 mm or more. The thickness T of the hydrocarbon-based ion exchange membrane 100 is not particularly limited, and can be, for example, 30 μm to 100 μm.

[0080] The hydrocarbon-based ion exchange membrane 100 is characterized in that the rate of change of its thickness T is greater than the rate of change of its length L. Therefore, the hydrocarbon-based ion exchange membrane 100 can provide sufficient space in the thickness T direction to form a pattern.

[0081] The first intermediate 200, obtained by immersing a hydrocarbon-based ion exchange membrane 100 in a solvent at approximately 80°C for about 4 hours, can have a Young's modulus of 100 MPa or lower. There is no particular limitation on the lower limit of the Young's modulus; for example, it can be 50 MPa or higher. When the Young's modulus of the first intermediate 200 is 100 MPa or lower, the first intermediate 200 can undergo creep deformation due to the pressure applied by the template.

[0082] Figure 3 This describes the steps for obtaining the second intermediate. The second intermediate 400 can be obtained by stacking templates 300 on at least one surface, preferably two surfaces, of the first intermediate 200 and applying pressure in the stacking direction of the templates 300.

[0083] The template 300 may have a mesh shape, or it may be a mesh formed by lines intertwined in a mesh shape. In some embodiments, the term "mesh shape" in relation to the template refers to a mesh structure formed by intersecting lines or filaments. The diameter of the lines is not particularly limited, and may be, for example, from 10 μm to 30 μm. The diameter of the lines may refer to the diameter of a cross-section of a line cut perpendicular to its length. The mesh spacing of the template 300 is not particularly limited, and may be, for example, from 10 μm to 30 μm. The mesh spacing of the template 300 may refer to the spacing between the lines forming the mesh. The aperture ratio of the template 300 is not particularly limited, and may be, for example, from 10% to 50%. The aperture ratio of the template 300 may refer to the area of ​​the spacing between the lines in the total area of ​​the template 300.

[0084] The material of template 300 preferably has a higher stiffness than that of the first intermediate 200. Since the first intermediate 200 is a hydrated hydrocarbon-based ion exchange membrane 100, its stiffness (e.g., Young's modulus) can range from a few MPa to tens of MPa. Because template 300 is required to induce creep deformation in the first intermediate 200, the stiffness of template 300 needs to be at least higher than that of the first intermediate 200. Specifically, template 300 may comprise stainless steel. In some embodiments, template 300 may be made of stainless steel.

[0085] The template 300 can have a width of 300 mm or more and a length of 500 mm or more. There is no particular upper limit to the width and length of the template 300, which can be appropriately adjusted according to the expected size of the first intermediate 200. The size of the first intermediate 200 can refer to its width and length, and the size of the first intermediate 200 can be equal to, greater than, or smaller than the size of the template 300. For example, the size of the first intermediate 200 can be 90% to 110% of the size of the template 300. According to the present invention, since the size of the template 300 can be freely adjusted, it has advantages over conventional techniques such as patterning methods using ionomer solutions, patterning methods using nanoparticles, and patterning methods using plasma in preparing large-area patterned electrolyte membranes.

[0086] The second intermediate 400 may be formed by pressing the template 300 onto at least one surface of the first intermediate 200, preferably on both surfaces.

[0087] The step of obtaining the second intermediate 400 may involve stacking a template 300 on at least one surface, preferably two surfaces, of the first intermediate 200, and applying a pressure of 5 MPa to 15 MPa in the stacking direction at a temperature of 70°C to 90°C, causing the first intermediate 200 to undergo creep deformation. Here, creep deformation can refer to the phenomenon that deformation continues over time under a constant load applied to the first intermediate 200. When the temperature and pressure conditions are met, the first intermediate 200 can undergo creep deformation through the template 300.

[0088] Figure 4 This is used to illustrate the steps for obtaining an electrolyte membrane.

[0089] An electrolyte membrane can be obtained by dehydrating the second intermediate 400 and removing the template 300 from the second intermediate 400. Since the first intermediate 200 reverts to a hydrocarbon-based ion exchange membrane 100 and regains its mechanical properties when dehydrated while constrained by the template 300, creep recovery deformation can be minimized upon removal of the template 300, thereby permanently retaining a shape corresponding to the template 300 on at least one surface, preferably two surfaces, of the hydrocarbon-based ion exchange membrane 100. In some embodiments, the term "corresponds" means that the shape, size, or pattern on the membrane substantially reflects or matches the geometry of the template. Specifically, when the membrane is imprinted under pressure from the template, the resulting embedded pattern aligns with the contour or opening of the template (i.e., originates from the contour or opening of the template).

[0090] The step of obtaining the electrolyte membrane can be to press the second intermediate 400 at a temperature of 70°C to 90°C for 1 to 2 hours to dehydrate it, and then remove the template. When the pressing temperature and time conditions are met, the second intermediate 400 can be sufficiently dehydrated.

[0091] Figure 5 This describes a method for manufacturing a membrane electrode assembly according to the present invention. Figure 6 This is an enlarged cross-sectional view of the membrane electrode assembly according to the present invention.

[0092] The method of manufacturing a membrane electrode assembly may include the following steps: manufacturing a pair of electrodes 20 and 20' by coating a catalyst slurry onto two surfaces of an electrolyte membrane 10.

[0093] A pattern with a shape corresponding to the shape of the template 300 can be formed and embedded in at least one surface, preferably two surfaces, of the electrolyte membrane 10.

[0094] The depth of the pattern embedded in the electrolyte membrane 10 can be 40% or higher of the cross-sectional diameter of the lines of the template 300. There is no particular upper limit to the pattern depth, and it can be, for example, 80% or lower, 70% or lower, or 60% or lower. If the pattern depth is less than 40%, the improvement in water flow rate and hydrogen ion conductivity of the electrolyte membrane 10 may be minimal; if the pattern depth exceeds 80%, the mechanical properties of the electrolyte membrane 10 may deteriorate.

[0095] Catalyst slurry may contain catalyst, ionomer, solvent, etc.

[0096] The catalyst may include platinum (Pt / C) supported on a carbon support. The platinum content is not particularly limited and may be, for example, about 40% to 60% by weight of the total catalyst weight.

[0097] Ionomers may include perfluorosulfonic acid ionomers, hydrocarbon ionomers, etc. Perfluorosulfonic acid ionomers may have a polytetrafluoroethylene (PTFE) backbone and side chains containing sulfonic acid groups (-SO3H), and may preferably include Nafion. Hydrocarbon ionomers may be the same as the hydrocarbon ion exchange membrane 100 described above.

[0098] Solvents may include alcohols, amides, ketones, carbonates, and ethers. Alcohols may include alcohols having 1 to 4 carbon atoms. Amides may include formamide (FA), N-methylformamide (NMFA), N,N-dimethylformamide (DMF), acetamide (AA), N-methylacetamide (NMAA), N,N-dimethylacetamide (DMA), and N-methyl-2-pyrrolidone (NMP), preferably N-methyl-2-pyrrolidone (NMP). Ketones may include acetone, methyl ethyl ketone (MEK), methyl butyl ketone (MBK), and methyl isobutyl ketone (MIBK). Carbonate organic solvents can include ethylene carbonate, propylene carbonate, 1,2-butene carbonate, 2,3-butene carbonate, 1,2-pentene carbonate, 2,3-pentene carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, etc. Ether organic solvents can include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, 1,4-dioxane, tetrahydrofuran, anisole, etc.

[0099] The solids concentration of the catalyst slurry can be 10% to 15% by weight. Solids concentration refers to the content of solid components such as catalyst and ionomers in the catalyst slurry, excluding solvent content.

[0100] There are no particular limitations on the method for preparing catalyst slurry. For example, catalyst slurry can be prepared by adding catalyst and ionomer to solvent, mixing with a paste mixer for about 30 minutes, dispersing with a high-shear homogenizer for about 60 minutes, and defoaming for about 20 minutes.

[0101] The catalyst slurry can be coated onto the electrolyte membrane 10 by spraying or bar coating to fabricate the electrode 20. Since a pattern corresponding to the shape of the template 300 is formed to embed into at least one surface, preferably two surfaces, of the electrolyte membrane 10, the catalyst slurry can fill the pattern and form a shape such that… Figure 6 The electrode 20 is shown. As a result, the interface between the electrolyte membrane 10 and the electrode 20 is enlarged, thereby increasing the adhesion strength between the two components, which can lead to improved electrochemical performance of the membrane electrode assembly.

[0102] Other embodiments of the present invention will be described in more detail below through preparation examples and embodiments. The following preparation examples and embodiments are merely illustrative examples to help understand the present invention, and the scope of the present invention is not limited thereto.

[0103] Preparation Example 1-1

[0104] The first intermediate was prepared by hydrating a hydrocarbon-based ion exchange membrane.

[0105] Piperion anion exchange membrane from Versogen was used as the hydrocarbon-based ion exchange membrane. The thickness of this hydrocarbon-based ion exchange membrane was approximately 40 μm. The hydrocarbon-based ion exchange membrane was immersed in water at approximately 80°C for approximately 4 hours.

[0106] Comparative Preparation Example 1-1

[0107] The first intermediate was prepared by immersing the same hydrocarbon-based ion exchange membrane as in Preparation Example 1-1 in water at about 30°C for about 4 hours.

[0108] Comparative Preparation Example 2-1

[0109] The first intermediate was prepared by immersing the same hydrocarbon-based ion exchange membrane as in Preparation Example 1-1 in water at about 50°C for about 4 hours.

[0110] Figure 7 The length change rate, thickness change rate, and water content of the first intermediates prepared according to Preparation Example 1-1, Comparative Preparation Example 1-1, and Comparative Preparation Example 2-1 are shown. Specific values ​​are shown in Table 1 below.

[0111] [Table 1]

[0112]

[0113] refer to Figure 7 As shown in Table 1, the higher the hydration temperature of hydrocarbon-based ion exchange membranes, the greater the dimensional change rate and water content. As shown in Preparation Example 1, when the hydration temperature is 80°C or higher, it can be seen that the thickness change rate is 30% or higher, which provides sufficient space for pattern formation.

[0114] Figure 8 The tensile strengths of the first intermediates prepared according to Preparation Example 1-1, Comparative Preparation Example 1-1, and Comparative Preparation Example 2-1 are shown. The tensile strength, Young's modulus, and elongation at break of each first intermediate are shown in Table 2 below.

[0115] [Table 2]

[0116]

[0117] Given that the Young's modulus (characterizing mechanical stiffness) was lowest at a hydration temperature of 80°C in Preparation Example 1-1, it can be seen that its degree of plasticization was the highest. Therefore, the first intermediate of Preparation Example 1-1 can undergo creep deformation due to mechanical stress, thereby enabling patterning.

[0118] Preparation Examples 1-2

[0119] Figure 9 To prepare the template used in Examples 1-2. Figure 10 for Figure 9 Optical image of the template. Figure 11 for Figure 9 Laser outline image of the template.

[0120] A mesh made of SUS316L material was used as a template, provided in roll form with a width of approximately 300 mm and a length of approximately 500 mm. The diameter of the lines constituting the template was approximately 20 μm, the spacing between the lines was approximately 20 μm, and the aperture ratio was approximately 25%. The stiffness of the template was approximately 176 GPa, which was higher than the stiffness of the first intermediate in Preparation Example 1-1.

[0121] After stacking templates on the two surfaces of the first intermediate in Preparation Example 1-1, a pressure of about 10 MPa is applied in the stacking direction at a temperature of about 80°C to obtain the second intermediate.

[0122] The second intermediate was dehydrated by compression at about 80°C for about 1 to 2 hours, and then the template was removed to obtain an electrolyte membrane.

[0123] Comparative preparation examples 1-2

[0124] Except for using the first intermediate in Comparative Preparation Example 1-1, the electrolyte membrane was prepared in the same manner as in Preparation Example 1-2.

[0125] Comparative Preparation Example 2-2

[0126] Except for using the first intermediate in Comparative Preparation Example 2-1, the electrolyte membrane was prepared in the same manner as in Preparation Example 1-2.

[0127] Figure 12 Optical images and laser profile images of the electrolyte membranes prepared in Examples 1-2 are presented for comparison. Figure 13 Optical and laser profile images of the electrolyte membrane prepared in Comparative Example 2-2 are provided. Figure 14 Optical images and laser profile images of the electrolyte membranes prepared according to Examples 1-2.

[0128] Figure 15 Images are shown to illustrate the results of scanning electron microscopy analysis of the surface and cross-section of the electrolyte membranes prepared according to Comparative Examples 1-2. Figure 16 Images are shown to illustrate the results of analysis of the surface and cross-section of the electrolyte membrane prepared according to Comparative Example 2-2 using scanning electron microscopy. Figure 17 Images are shown to illustrate the results of analyzing the surface and cross-section of the electrolyte membranes prepared according to Examples 1-2 using scanning electron microscopy.

[0129] In the electrolyte membranes prepared in Examples 1-2, the mechanical stiffness of the first intermediate decreased the most, indicating the most significant plasticization and the largest thickness change rate, resulting in a clearly imprinted pattern shape. Scanning electron microscopy results of the cross-section showed that the pattern depth of the electrolyte membranes prepared in Examples 1-2 was approximately 47% or greater of the diameter of the lines constituting the template. On the other hand, the pattern fidelity of the electrolyte membranes prepared in Comparative Examples 1-2 and 2-2 was lower.

[0130] Example

[0131] The method for manufacturing membrane electrode assembly is as follows: a catalyst slurry containing Pt / C, ionomer and alcohol solvent is coated onto the two surfaces of the electrolyte membrane of Preparation Examples 1-2 by spraying to form electrodes.

[0132] Comparative example

[0133] The membrane electrode assembly was fabricated in the same manner as in the examples using an electrolyte membrane without a patterned surface. A Piperion anion exchange membrane from Versogen, with a thickness of approximately 40 μm, was used as the electrolyte membrane.

[0134] Table 3 below shows the thickness, tensile strength, Young's modulus, and elongation at break of the electrolyte membranes used in the examples and comparative examples.

[0135] [Table 3]

[0136]

[0137] Referring to Table 3, the electrolyte membranes of the Examples and Comparative Examples have substantially the same thickness, tensile strength, Young's modulus, and elongation at break. In the Examples, the thickness is reduced and the Young's modulus is increased due to dehydration compression during the patterning process.

[0138] It can be confirmed that even with patterning, the mechanical properties of the electrolyte membrane are not affected, because the electrolyte membrane of the embodiment has undergone the patterning treatments described in Preparation Examples 1-1 and 1-2 performed on the electrolyte membrane of the comparative example.

[0139] Table 4 below shows the resistance and hydrogen ion conductivity of the electrolyte membranes used in the examples and comparative examples. The hydrogen ion conductivity was measured using a four-point measurement method.

[0140] [Table 4]

[0141]

[0142] Referring to Table 4, the electrolyte membrane of the embodiment exhibits lower resistance and higher hydrogen ion conductivity than the electrolyte membrane of the comparative example. It can be seen that the patterning treatment according to the present invention does not adversely affect the electrochemical performance of the electrolyte membrane, but rather improves hydrogen ion conductivity by providing localized hydrogen ion transfer characteristics through patterning.

[0143] Figure 18 Images showing the results of analyzing the surface and cross-section of the membrane electrode assembly according to the comparative example using scanning electron microscopy. Figure 19 Images illustrating the results of scanning electron microscopy analysis of the surface and cross-section of a membrane electrode assembly according to an embodiment. Reference Figure 19 As can be seen, the electrodes of the membrane electrode assembly according to the embodiment are well formed along the pattern of the electrolyte membrane. This differs from the interface result between the electrolyte membrane and the electrode in the comparative example where no pattern was formed. According to the embodiment, the interlocking structure at the interface between the electrolyte membrane and the electrode improves the bonding force, which can lead to improved durability. Furthermore, the electrolyte membrane, which is locally thinned by the pattern, can promote the movement of water and hydrogen ions, thereby reducing resistance and improving mass transfer characteristics. To verify these effects, the shear stress and adhesion strength of each membrane electrode assembly were measured to evaluate the interfacial adhesion of the membrane electrode assemblies according to the embodiment and the comparative example. Figure 20 A graph is provided to illustrate the adhesion strength measurement results of the membrane electrode assemblies according to the embodiments and comparative examples. Specifically, the adhesion strength was measured using a peel strength tester. Table 5 below shows the shear stress and adhesion strength of the membrane electrode assemblies according to the embodiments and comparative examples.

[0144] [Table 5]

[0145]

[0146] refer to Figure 20 According to Table 5, the shear stress of the embodiment was increased by about 13.4% compared with the comparative example, and the adhesion strength of the embodiment was increased by about 164.05% compared with the comparative example.

[0147] The strong bonding between the electrolyte membrane and the electrode shown in the embodiment means that the peeling problem that occurs in the long-term operation of the electrochemical device using the electrolyte membrane and electrode can be effectively alleviated, thereby improving durability.

[0148] The embodiments of the present invention have been described in detail above, but the scope of the present invention is not limited to the above embodiments. Various modifications and improvements made by those skilled in the art using the basic concepts of the present invention (as defined in the patent claims) are also included within the scope of the present invention.

Claims

1. A method of preparing an electrolyte membrane for a membrane electrode assembly, the method comprising the steps of: obtaining a first intermediate by hydrating a hydrocarbon-based ion exchange membrane; obtaining a second intermediate by stacking a template on at least one surface of the first intermediate and applying pressure in a stacking direction; and obtaining the electrolyte membrane by dehydrating the second intermediate and removing the template from the second intermediate, wherein the electrolyte membrane includes a pattern corresponding to a shape of the template.

2. The method of claim 1, wherein, The step of obtaining the first intermediate is soaking the hydrocarbon-based ion exchange membrane in a solvent at 70 to 90℃ for 4 to 6 hours.

3. The method of claim 1, wherein, The first intermediate obtained by soaking the hydrocarbon-based ion exchange membrane in a solvent at about 80℃ for about 4 hours has a water content of 60% by weight or more.

4. The method of claim 1, wherein, When the hydrocarbon-based ion exchange membrane is soaked in a solvent at about 80℃ for about 4 hours, the hydrocarbon-based ion exchange membrane has a length change rate of 10% or more.

5. The method of claim 1, wherein, When the hydrocarbon-based ion exchange membrane is soaked in a solvent at about 80℃ for about 4 hours, the hydrocarbon-based ion exchange membrane has a thickness change rate of 30% or more.

6. The method of claim 1, wherein, The first intermediate obtained by soaking the hydrocarbon-based ion exchange membrane in a solvent at about 80℃ for about 4 hours has a Young's modulus of 100 MPa or less.

7. The method of claim 1, wherein, The template has a mesh shape in which lines are intertwined with each other in a mesh shape.

8. The method of claim 1, wherein, The template has a rigidity higher than that of the first intermediate.

9. The method of claim 1, wherein, The template comprises stainless steel.

10. The method of claim 1, wherein, The template has a width of 300 mm or more and a length of 500 mm or more, and the first intermediate has a size equal to or greater than that of the template.

11. The method of claim 1, wherein, The template has a width of 300 mm or more and a length of 500 mm or more, and the first intermediate has a size equal to or less than that of the template.

12. The method of claim 1, wherein, The step of obtaining the second intermediate is stacking the template on at least one surface of the first intermediate and applying pressure in a stacking direction at a temperature of 70 to 90℃ at a pressure of 5 to 15 MPa.

13. The method of claim 1, wherein, The step of obtaining the electrolyte membrane is dehydrating the second intermediate by compressing the second intermediate at a temperature of 70 to 90℃ for 1 to 2 hours and removing the template.

14. A method of manufacturing a membrane electrode assembly, the method comprising the steps of: A catalyst slurry is coated on both surfaces of the electrolyte membrane prepared according to claim 1 to manufacture a pair of electrodes, wherein the electrodes are filled in spaces formed to be embedded in the electrolyte membrane. 15.An electrolyte membrane for a membrane electrode assembly, the electrolyte membrane comprising a hydrocarbon-based ion exchange membrane, wherein a pattern of the hydrocarbon-based ion exchange membrane has a shape corresponding to a pattern of a template, the pattern is formed to be embedded on at least one surface of the hydrocarbon-based ion exchange membrane, and the template is a mesh shape in which lines are intertwined with each other in a mesh shape. 16.The electrolyte membrane of claim 15, wherein the hydrocarbon-based ion exchange membrane has a water content of 60% by weight or more.

17. The electrolyte membrane according to claim 15, wherein the carbon-hydrogen compound-based ion exchange membrane has a longitudinal variation rate of 10% or more.

18. The electrolyte membrane according to claim 15, wherein the carbon-hydrogen compound-based ion exchange membrane has a width direction variation rate of 30% or more.

19. The electrolyte membrane according to claim 15, wherein the carbon-hydrogen compound-based ion exchange membrane has a Young's modulus of 100 MPa or less.

20. The electrolyte film of claim 15, wherein, The depth of the pattern formed to be embedded in the carbon-hydrogen compound-based ion exchange membrane is 40% or more of the cross-sectional diameter of the line of the template.

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