Metal diaphragm and manufacturing method thereof

Abstract

The invention relates to a metal diaphragm and a manufacturing method thereof. According to the metal diaphragm and the manufacturing method thereof, excellent conductivity, corrosion resistance and excellent adhesive force of the coating can be realized.

Description

Technical Field

[0001] The present application relates to a metal diaphragm and a method for manufacturing the same. Background Art

[0002] In recent years, to combat global warming, the powertrain has shifted from internal combustion engines (ICEs) to electric vehicles (EVs) or hydrogen fuel cell electric vehicles (FCEVs). The fuel cells used in hydrogen fuel cell electric vehicles (FCEVs) are not only used to power industrial and domestic applications and vehicles, but are also used to power small electronic devices such as portable devices. Their use as a highly efficient and clean energy source is expanding as a means of energy conservation and environmental protection.

[0003] A fuel cell is a power generation device that converts the chemical energy of fuel into electrical energy through an electrochemical reaction within a stack, using the energy generated by the reaction between hydrogen and oxygen to generate electricity. Specifically, a fuel cell uses hydrogen as fuel, which undergoes an oxidation reaction to produce hydrogen ions (protons) and electrons. These hydrogen ions and electrons then react electrochemically with oxygen in the air to produce water, while the flow of electrons generates electricity.

[0004] This type of hydrogen fuel cell consists of a membrane electrode assembly coated with catalyst powder, a gas diffusion layer (GDL), and a separator. While the hydrogen fuel cell can theoretically generate a voltage of 1.229V, due to various limitations, such as the inherent characteristics of the aforementioned components and the characteristics between components, its operating voltage is limited to 0.6V to 0.8V.

[0005] Among these components, the diaphragm must perform multiple functions, including structural support for the gas diffusion layer, collection and transmission of generated current, transport and removal of reaction gases, and transportation of cooling water to remove reaction heat. Therefore, it must possess excellent electrical and thermal conductivity, airtightness, and chemical stability. Specifically, the diaphragm's structure inevitably dissolves hydrogen ions in water and forms acids, so corrosion resistance must be ensured. Furthermore, since the reaction between hydrogen and oxygen releases electrons, which must be transferred through the diaphragm, the diaphragm must also have electrical conductivity.

[0006] The U.S. Department of Energy (DOE), an environmental energy research center, requires materials that can withstand pH values ​​of 4 or higher as separators. In addition, actual corrosion tests were conducted at pH values ​​of 1 to 3 and 0.6V vs SCE In order to ensure corrosion resistance, the material in this environment must be vs SCE The zeta potential of 10 μA / cm 2 or less current density, exhibiting 20 mΩ·cm at a pressure of 133 N / m2 Or less interface contact resistance. In addition, the material is required to have 100S / cm 2 Or greater conductivity or 20mΩ·cm 2 or less contact resistance.

[0007] Metal materials initially appear to be 10 4 S / cm 2 However, metal materials suffer from reduced electrical conductivity due to corrosion. Furthermore, taking graphite as an example, thickness reduction is difficult to control due to crack formation and hydrogen permeability during processing. Extreme care must be taken during processing, and there are limitations in ensuring weight reduction and economic feasibility.

[0008] To address these issues, Patent Document 1 (Korean Patent No. 0839193) uses a metal separator that forms a coating containing an organic binder and carbon particles on a metal substrate. This metal separator ensures corrosion resistance, but suffers from the problem of reduced electrical conductivity due to the organic binder.

[0009] To address this issue, the organic binder is removed to ensure conductivity. However, this significantly reduces the adhesion of the coating, making it easily removable even under low shear stress. Therefore, to address these issues, a metal diaphragm with excellent conductivity, corrosion resistance, and adhesion, as well as a method for manufacturing the same, is needed. Summary of the Invention

[0010] Technical Purpose

[0011] The object of the present application is to provide a metal diaphragm having excellent electrical conductivity and corrosion resistance as well as excellent coating adhesion, and a method for manufacturing the same.

[0012] Technical Solution

[0013] To achieve the above objectives, the metal diaphragm of the present application includes a metal substrate and a coating layer formed on the surface of the metal substrate and containing a conductive filler and an inorganic polymer.

[0014] The conductive filler may include one or more selected from carbon black, carbon nanotubes, graphene, and carbon fibers.

[0015] Furthermore, the inorganic polymer may be a polymer including a bond between a Group IVB transition metal element and an oxygen atom.

[0016] In addition, the inorganic polymer may be included in the coating layer in an amount of 0.01 to 50 parts by weight relative to 100 parts by weight of the conductive filler.

[0017] Furthermore, the coating may have a thickness of 10 nm to 5000 nm.

[0018] Furthermore, the coating can have a 1 mΩ·cm 2 Up to 20mΩ·cm 2 contact resistance.

[0019] Furthermore, the coating can have a 0.1 μA / cm 2 Up to 10μA / cm 2 of corrosion current.

[0020] In addition, the manufacturing method of the metal diaphragm of the present application relates to a manufacturing method of a metal diaphragm including a metal substrate and a coating, wherein the coating is formed on the surface of the metal substrate and contains a conductive filler and an inorganic polymer, and the method includes: a mixing step, mixing the conductive filler and the organic binder and preparing a coating mixture; a coating step, coating the surface of the metal substrate with the coating mixture, temporarily drying it, and forming a coating; a first heat treatment step, performing a first heat treatment on the temporarily dried coating and removing the organic binder in the coating; and a second heat treatment step, introducing liquid metal-based organic matter into the area where the organic binder has been removed, and then performing a second heat treatment, and gelling the liquid metal-based organic matter into an inorganic polymer.

[0021] In addition, the conductive filler may be included in the coating mixture in an amount of 40 to 600 parts by weight relative to 100 parts by weight of the organic binder.

[0022] In addition, temporary drying may be performed at a temperature of 80° C. to 200° C. for 10 seconds to 60 minutes.

[0023] In addition, the first heat treatment may be performed at 250° C. to 900° C. under a pressure of 0.05 Pa to 0.5 Pa for 10 seconds to 24 hours.

[0024] Furthermore, the method for manufacturing the metal diaphragm may further include a coating thickness adjustment step for reducing the thickness of the coating from which the organic binder has been removed.

[0025] In addition, the liquid metal-based organic material may exist in a state where the metal-based organic material represented by the following Chemical Formula 1 is dispersed in a liquid dispersion medium:

[0026] [Chemical Formula 1]

[0027] M(OR)4,

[0028] In the above Chemical Formula 1, M is a Group IVB transition metal element, and R is a linear or branched alkyl group having 1 to 6 carbon atoms.

[0029] Furthermore, the liquid metal-based organic may be introduced into the region from which the organic binder has been removed by immersing the metal substrate having the coating from which the organic binder has been removed in the liquid metal-based organic. The immersion may be performed for 1 second to 10 minutes.

[0030] In addition, the second heat treatment may be performed at 250° C. to 900° C. for 10 seconds to 24 hours in a vacuum atmosphere.

[0031] Effects of the Invention

[0032] According to the metal separator and the method for manufacturing the same of the present application, not only are the electrical conductivity and corrosion resistance excellent, but the adhesion of the coating layer is also excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a diagram showing a metal diaphragm according to one embodiment of the present application by way of example;

[0034] Figure 2 is a diagram showing a metal diaphragm that has undergone a coating step by way of example, to describe the coating step according to one embodiment of the present application;

[0035] Figure 3 is a diagram showing a metal diaphragm that has undergone a first heat treatment step by way of example, to describe the first heat treatment step according to one embodiment of the present application;

[0036] Figure 4 is a diagram showing a metal diaphragm that has undergone a second heat treatment step by way of example, to describe the second heat treatment step according to one embodiment of the present application;

[0037] Figure 5 This is a 10,000-fold magnified image obtained by photographing the surface of the metal diaphragm that has undergone the coating step in Example 1 using a scanning electron microscope;

[0038] Figure 6 is a 10,000-times magnified image obtained by photographing the surface of the metal diaphragm that has undergone the first heat treatment step in Example 1 using a scanning electron microscope; and

[0039] Figure 7 This is a 10,000-times magnified image of the surface of the metal diaphragm that has undergone the second heat treatment step in Example 1, taken with a scanning electron microscope. DETAILED DESCRIPTION

[0040] Hereinafter, the metal diaphragm of the present application is described with reference to the accompanying drawings, which are illustrative and the metal diaphragm of the present application is not limited to the accompanying drawings.

[0041] Figure 1FIG is a diagram showing a metal diaphragm according to an embodiment of the present application in an exemplary manner. Figure 1 As shown, the metal diaphragm 100 of the present application includes a metal substrate 110 and a coating 120. According to the metal diaphragm 100 of the present application, not only can the electrical conductivity and corrosion resistance be excellent, but the adhesion of the coating 120 is also excellent. In this specification, the term "coating adhesion" refers to the strength of the coating adhering to the metal substrate.

[0042] The metal substrate 110 is a metal material used for the metal diaphragm for fuel cells. The type of metal substrate 110 is not particularly limited, and any metal substrate used in metal diaphragms for fuel cells can be used without restriction. For example, a substrate made of titanium, aluminum, magnesium, copper, stainless steel, or alloys thereof can be used as the metal substrate 110. Specifically, SUS 300 series steel, i.e., stainless steel, can be used as the metal substrate 110. By including such a metal substrate 110, the metal diaphragm 100 can have excellent electrical conductivity.

[0043] Coating 120 is a layer applied to the surface of metal substrate 110. It is formed on the surface of metal substrate 110 and includes conductive filler 121 and inorganic polymer 122. By being formed on the surface of metal substrate 110, coating 120 not only improves the corrosion resistance of metal substrate 110 but also enhances the adhesion of coating 120. In this specification, the term "surface" refers to an outer surface located on one, both, or all sides of a metal substrate.

[0044] The conductive filler 121 is a substance having electrical conductivity. For example, the conductive filler 121 may include one or more selected from carbon black, carbon nanotubes, graphene, and carbon fibers. By including the conductive filler 121 in the coating 120, the electrical conductivity of the metal diaphragm 100 can be improved.

[0045] In one embodiment, the conductive filler 121 may have a particle size of 10 nm to 70 nm. Specifically, the particle size of the conductive filler 121 may have a lower limit of 20 nm or more or 30 nm or more, and an upper limit of 60 nm or less, 50 nm or less, or 40 nm or less. By having such a particle size, the conductive filler 121 can improve electrical conductivity.

[0046] The inorganic polymer 122 is a polymer having an inorganic substance other than carbon as a skeleton. For example, the inorganic polymer 122 may be a polymer containing a bond between a Group IVB transition metal element and an oxygen atom. Specifically, the Group IVB transition metal element may be titanium (Ti), zirconium (Zr), hafnium (Hf), or (Rf) element. That is, the inorganic polymer 122 may be titanium sol-gel, zirconium sol-gel, hafnium sol-gel or Sol-Gel: By including the inorganic polymer 122 in the coating layer 120, not only the electrical conductivity and corrosion resistance of the metal diaphragm 100 can be improved, but also the adhesion of the coating layer 120 can be improved.

[0047] In one embodiment, the inorganic polymer 122 may be included in the coating layer 110 at 0.01 to 50 parts by weight relative to 100 parts by weight of the conductive filler 121. Specifically, the inorganic polymer 122 may be included in the coating layer 110 at 0.05 to 40 parts by weight or 0.1 to 30 parts by weight relative to 100 parts by weight of the conductive filler 121. By including the inorganic polymer 122 in the coating layer 110 at such a content, not only can the metal diaphragm 100 have excellent electrical conductivity and corrosion resistance, but the coating layer 120 also has excellent adhesion.

[0048] In another embodiment, the coating 120 may have a thickness of 10 nm to 5000 nm. Specifically, the thickness of the coating 120 may have an upper limit of 4000 nm or less, 3000 nm or less, 2000 nm or less, or 1000 nm or less. By having the above thickness range, the coating 120 can be stable without losing electrical conductivity. In contrast, if the coating 120 exceeds the above thickness range, many pores may form inside, resulting in many defects, which in turn may deteriorate electrical conductivity and corrosion resistance.

[0049] In addition, the coating 120 may have a 2 Up to 20mΩ·cm 2 Specifically, the contact resistance of the coating 120 may be 15 mΩ·cm 2 or less or 10mΩ·cm 2 Since the coating layer 120 has the above-mentioned contact resistance, the metal diaphragm 100 can have excellent electrical conductivity.

[0050] Furthermore, the coating 120 may have a thermal conductivity of 0.1 μA / cm 2 Up to 10μA / cm 2 Specifically, the upper limit of the corrosion current of the coating 120 may be 9 μA / cm 2 Or less, 8μA / cm 2 or less, or 7μA / cm 2 Since the coating layer 120 has the above-mentioned corrosion current, the metal diaphragm 100 can have excellent corrosion resistance.

[0051] The present application also relates to a method for manufacturing a metal diaphragm. The method for manufacturing the metal diaphragm is related to the method for manufacturing the metal diaphragm described above. The specific details of the metal diaphragm described below may be omitted because the contents described in the metal diaphragm described above are also applicable.

[0052] The method for manufacturing a metal diaphragm of the present application includes a mixing step, a coating step, a first heat treatment step, and a second heat treatment step. According to the method for manufacturing a metal diaphragm of the present application, not only the electrical conductivity and corrosion resistance are excellent, but also the adhesion of the coating is excellent.

[0053] The mixing step is a step of preparing a coating mixture for coating the surface of the metal substrate, and is performed by mixing the conductive filler with the organic binder. That is, the conductive filler can be present in the organic binder in a dispersed state through the mixing step.

[0054] In one embodiment, relative to the organic binder of 100 weight parts, the conductive filler can be included in the coating mixture with 40 to 600 weight parts. Specifically, relative to the organic binder of 100 weight parts, the conductive filler can be included in the coating mixture with 60 to 540 weight parts, 80 to 480 weight parts, or 100 to 420 weight parts. By including the conductive filler in the coating mixture with the above-mentioned content, the electrical conductivity of the metal diaphragm can be excellent. In addition, on the contrary, relative to the conductive filler of 100 weight parts, the organic binder can be included in the coating mixture with 16 to 250 weight parts. Specifically, relative to the conductive filler of 100 weight parts, the organic binder can be included in the coating mixture with 18 to 167 weight parts, 20 to 125 weight parts, or 23 to 100 weight parts. By including the organic binder in the coating composition with the above-mentioned content, the conductive filler can be applied to the surface of the metal substrate, thereby improving the corrosion resistance of the metal diaphragm.

[0055] As the type of organic binder, a polymer binder that is thermally decomposed at a temperature of 300° C. or higher may be used. For example, the organic binder may include acrylic resin, modified alkyd resin, melanin resin ( ), or a mixture thereof. Specifically, a phenol-modified alkyd resin can be used as the modified alkyd resin. By including the above-mentioned type of polymer binder that thermally decomposes at the above-mentioned temperature, the organic binder can be removed in the following first heat treatment step.

[0056] Figure 2 FIG. 1 is a diagram showing a metal diaphragm that has undergone a coating step in an exemplary manner to describe the coating step according to one embodiment of the present application. Figure 2 As shown, the coating step is a step of forming a coating layer 220 on the surface of the metal substrate 210 using the coating mixture prepared in the mixing step. This step is performed by applying the coating mixture to the surface of the metal substrate 210 and temporarily drying it. By including the coating step in the method for manufacturing the metal diaphragm, the conductive filler 221 can be coated on the surface of the metal substrate 210 using the organic binder 223.

[0057] Spray coating, physical vapor deposition, etc. can be used as a method of applying the coating mixture.

[0058] The coating mixture may be applied to a thickness of 0.01 to 20 μm, specifically 0.02 to 18 μm, 0.03 to 15 μm, 0.04 to 13 μm, or 0.05 to 10 μm. The coating mixture may be applied to a thickness of 0.01 to 20 μm, specifically 0.02 to 18 μm, 0.03 to 15 μm, 0.04 to 13 μm, or 0.05 to 10 μm. The corrosion resistance of the metal diaphragm may be improved by applying the coating mixture to the aforementioned thickness.

[0059] Temporary drying refers to tack-free drying, in which the coating mixture is dried to the extent that it does not stick to other equipment or hands, and can be performed at a temperature of 80° C. to 200° C. for 10 seconds to 60 minutes. Specifically, temporary drying can be performed at a temperature of 85° C. to 200° C., 90° C. to 200° C., 95° C. to 200° C., or 100° C. to 200° C. for 20 seconds to 45 minutes or 30 seconds to 30 minutes. In this case, temporary drying can be performed in an oven.

[0060] Figure 3 FIG. 1 is a diagram showing a metal diaphragm that has undergone a first heat treatment step in an exemplary manner to describe the first heat treatment step according to one embodiment of the present application. Figure 3 As shown, the first heat treatment step is a step of performing heat treatment to remove the organic binder in the coating layer 220, and is performed by performing the first heat treatment on the temporarily dried coating layer 220. By performing the first heat treatment step in the method for manufacturing the metal diaphragm, the organic binder in the coating layer 220 can be thermally decomposed and removed, thereby forming a region H from which the organic binder in the coating layer 220 has been removed.

[0061] In one embodiment, the first heat treatment can be performed at a pressure of 0.05 Pa to 0.5 Pa at 250° C. to 900° C. for 10 seconds to 24 hours. Specifically, the first heat treatment can be performed at a pressure of 0.4 Pa or less, 0.3 Pa or less, 0.2 Pa or less, or 0.1 Pa or less at 300° C. to 800° C., 400° C. to 700° C., or 500° C. to 600° C. for 20 seconds to 19 hours, 30 seconds to 14 hours, 40 seconds to 9 hours, 50 seconds to 4 hours, 1 minute to 1 hour, 3 minutes to 50 minutes, 5 minutes to 40 minutes, 7 minutes to 30 minutes, 9 minutes to 20 minutes, or 10 minutes to 15 minutes. By performing the first heat treatment under the above conditions, the organic binder in the coating 220 can be completely removed. In this case, the pressure refers to the oxygen partial pressure in the low oxygen atmosphere. By performing the first heat treatment under the above low oxygen atmosphere, oxidation of the metal substrate can be prevented, thereby preventing the formation of an oxide layer on the metal substrate.

[0062] In another embodiment, the method for manufacturing a metal diaphragm further includes a thickness adjustment step. This thickness adjustment step is a step for adjusting the thickness of the coating layer from which the organic binder has been removed by the first heat treatment step. This step can be performed to reduce the thickness of the coating layer from which the organic binder has been removed. Specifically, the thickness adjustment step can be performed by repeatedly attaching and detaching an adhesive tape having an adhesive formed on one side to the surface of the coating layer from which the organic binder has been removed. By further including the thickness adjustment step in the method for manufacturing a metal diaphragm, the thickness of the coating layer from which the organic binder has been removed can be reduced to a desired thickness, thereby improving electrical conductivity.

[0063] Figure 4 FIG. 1 is a diagram showing a metal diaphragm that has undergone a second heat treatment step in an exemplary manner to describe the second heat treatment step according to one embodiment of the present application. Figure 4 As shown, the second heat treatment step is a step of introducing liquid metal-based organic matter into the region of the coating layer from which the organic binder has been removed by the first heat treatment, and then performing heat treatment to gel the liquid metal-based organic matter into an inorganic polymer 222. By performing the second heat treatment step in the method for manufacturing the metal diaphragm, the inorganic polymer 222 can be formed in the region of the coating layer from which the organic binder has been removed, resulting in excellent electrical conductivity and corrosion resistance of the coating layer 220, as well as excellent adhesion.

[0064] The liquid metal-based organic material may exist in a state where the metal-based organic material represented by the following Chemical Formula 1 is dispersed in a liquid dispersion medium.

[0065] [Chemical Formula 1]

[0066] M(OR)4,

[0067] In the above Chemical Formula 1, M is a Group IVB transition metal element, and R is a linear or branched alkyl group having 1 to 6 carbon atoms.

[0068] Specifically, the Group IVB transition metal element may be titanium (Ti), zirconium (Zr), hafnium (Hf) or (Rf) Element: By including the above-mentioned Group IVB transition metal element in the liquid metal-based organic material, the metal diaphragm 200 can have excellent electrical conductivity.

[0069] Furthermore, R may be a linear or branched alkyl group having 1 to 6 carbon atoms, specifically, a linear or branched alkyl group having 1 to 5 carbon atoms, 1 to 4 carbon atoms, or 1 to 3 carbon atoms. Specific examples of R may be a linear alkyl group consisting of an ethyl group, a methyl group, a propyl group, a butyl group, a pentyl group, or a hexyl group, or a branched alkyl group consisting of an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a 1-methyl-butyl group, a 1-ethyl-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an n-hexyl group, a 1-methylpentyl group, a 2-methylpentyl group, or a 4-methyl-2-pentyl group.

[0070] For example, the metal-based organic compound of the above Chemical Formula 1 may be titanium tetraisopropoxide (Ti(OCH(CH3)2)4), zirconium tetraisopropoxide (Zr(OCH(CH3)2)4), titanium tetraethoxide (Ti(OC2H5)4), or zirconium tetraethoxide (Zr(OC2H5)4).

[0071] In another embodiment, the metal-based organic compound may be filled with an inorganic acid. For example, nitric acid (HNO3), sulfuric acid (H2SO4), hydrochloric acid (HCl), phosphoric acid (H3PO4), perchloric acid (HClO4), hypochlorous acid (HClO), hydrofluoric acid (HF), acetic acid (CH3COOH), etc. can be used as the inorganic acid. By filling the metal-based organic compound with the above-mentioned inorganic acid, the metal contained in the metal-based organic compound can be stabilized.

[0072] Any dispersion medium known in the art can be used as the type of dispersion medium without particular limitation. By using the above-mentioned types as the dispersion medium, an inorganic oligomer can be formed.

[0073] In one embodiment, the liquid metal-based organic compound may have a solids content of 1% to 5%, specifically 1.5% to 4% or 2% to 3%. By ensuring that the solids content of the liquid metal-based organic compound meets the above range, not only can excellent electrical conductivity and corrosion resistance be achieved, but also excellent coating adhesion can be achieved.

[0074] Furthermore, the pH of the liquid metal-based organic may be greater than 0 to 4, specifically, 0.5 to 3 or 1 to 2. By making the pH of the liquid metal-based organic satisfy the above range, the metal contained in the metal-based organic can be stabilized.

[0075] In one embodiment, the liquid metal-based organic may be introduced into the region from which the organic binder has been removed by immersing the metal substrate having the coating from which the organic binder has been removed into the liquid metal-based organic.

[0076] For example, the liquid metal-based organic compound can be introduced into the region from which the organic binder has been removed by dipping the metal substrate having the coating from which the organic binder has been removed into the liquid metal-based organic compound. In this case, the dipping can be carried out for 1 second to 10 minutes. Specifically, the dipping can be carried out for 1 second to 8 minutes or 1 second to 5 minutes. By dipping for the above-mentioned time, the liquid metal-based organic compound can be introduced into all regions of the coating from which the organic binder has been removed.

[0077] In addition, the second heat treatment can be performed in a vacuum atmosphere at 250°C to 900°C for 10 seconds to 24 hours. Specifically, the second heat treatment can be performed in a vacuum atmosphere at 300°C to 800°C, 400°C to 700°C, or 500°C to 600°C for 20 seconds to 19 hours, 30 seconds to 14 hours, 40 seconds to 9 hours, 50 seconds to 4 hours, 1 minute to 1 hour, 3 minutes to 50 minutes, 5 minutes to 40 minutes, 7 minutes to 30 minutes, 9 minutes to 20 minutes, or 10 minutes to 15 minutes. By performing the second heat treatment under the above conditions, the liquid metal-based organic matter introduced into the coating area from which the organic binder has been removed can be gelled into the inorganic polymer 222. In this specification, the term "vacuum atmosphere" refers to a working environment having a vacuum state. For example, the pressure of the vacuum atmosphere can be 0.0001Pa to 0.01Pa. By performing the second heat treatment in the vacuum atmosphere, the liquid metal-based organic matter can be gelled into the inorganic polymer 222 , and the electrical conductivity can be improved by distorting the lattice of the titanium dioxide film generated during the gelation process.

[0078] Hereinafter, the present application will be described in more detail through Examples according to the present application and Comparative Examples not according to the present application, but the scope of the present application is not limited to the Examples presented below.

[0079] Example 1

[0080] Preparation of coating mixture

[0081] Carbon black having a particle size of 50 nm was used as a conductive filler, and acrylic resin was used as an organic binder. The conductive filler and the organic binder were diluted in an isopropyl alcohol organic solvent at a ratio of 5:5, thereby preparing a coating mixture.

[0082] Manufacturing of metal diaphragms

[0083] A titanium metal substrate (grade 1) was prepared, and the coating mixture prepared in Example 1 was applied to the surface of the titanium metal substrate with a thickness of 1 μm by roller coating. The metal substrate coated with the coating mixture was then placed in an oven and temporarily dried at 150°C for 5 minutes to form a coating on the surface of the metal substrate. At this time, the surface of the metal substrate with the coating formed was photographed, and the results were as follows: Figure 5 shown.

[0084] Then, the metal substrate with the coating was subjected to a first heat treatment at 600°C for 10 minutes in a low oxygen atmosphere of 0.1 Pa to remove the organic binder of the coating. Figure 6 shown.

[0085] Then, the metal substrate with the coating from which the organic binder has been removed is immersed in liquid metal-based organic matter (formed by dispersing titanium tetraisopropoxide in a dispersion medium, with a solid content of 1%, and adjusted to a pH of 2 with nitric acid) for 5 minutes, thereby introducing the liquid metal-based organic matter into the area from which the organic binder has been removed. Then, the metal substrate with the coating from which the liquid metal-based organic matter has been introduced is subjected to a second heat treatment of heating at 600°C for 10 minutes in a vacuum atmosphere of 0.01 Pa to gel the liquid metal-based organic matter into an inorganic polymer (TiO polymer), thereby manufacturing a metal diaphragm having a coating with a thickness of 1 μm formed on the surface of the metal substrate. At this time, the coating formed on the surface of the metal substrate of the metal diaphragm is photographed, and the results are as follows: Figure 7 shown.

[0086] Example 2

[0087] Preparation of coating mixture

[0088] A coating mixture was prepared in the same manner as in Example 1 above, except that the ratio of the conductive filler to the organic binder was changed to 7:3.

[0089] Manufacturing of metal diaphragms

[0090] A metal separator was manufactured in the same manner as in the above-mentioned Example 1, except that the coating mixture manufactured in the above-mentioned Example 2 was used.

[0091] Example 3

[0092] Preparation of coating mixture

[0093] A coating mixture was prepared in the same manner as in Example 1 above, except that the ratio of the conductive filler to the organic binder was changed to 8:2.

[0094] Manufacturing of metal diaphragms

[0095] A metal separator was manufactured in the same manner as in the above-mentioned Example 1, except that the coating mixture prepared in the above-mentioned Example 3 was used.

[0096] Example 4

[0097] Preparation of coating mixture

[0098] A coating mixture was prepared in the same manner as in Example 1 above, except that the ratio of the conductive filler to the organic binder was changed to 6:4.

[0099] Manufacturing of metal diaphragms

[0100] A metal separator was manufactured in the same manner as in the above-mentioned Example 1, except that the coating mixture prepared in the above-mentioned Example 4 was used.

[0101] Example 5

[0102] Preparation of coating mixture

[0103] Carbon black having a particle size of 50 nm was used as a conductive filler, and a phenol-modified alkyd resin was used as an organic binder. The conductive filler and the organic binder were diluted in an isopropyl alcohol organic solvent at a ratio of 6 to 4, thereby preparing a coating mixture.

[0104] Manufacturing of metal diaphragms

[0105] A metal separator was manufactured in the same manner as in the above-mentioned Example 1, except that the coating mixture prepared in the above-mentioned Example 5 was used.

[0106] Comparative Example 1

[0107] Preparation of coating mixture

[0108] In the same manner as in Example 1, a coating mixture was prepared.

[0109] Manufacturing of metal diaphragms

[0110] A titanium metal substrate (grade 1) was prepared, and the coating mixture prepared in Comparative Example 1 was applied to the surface of the titanium metal substrate by roller coating to a thickness of 1 μm. The metal substrate coated with the coating mixture was then placed in an oven and temporarily dried at 150° C. for 5 minutes to form a coating on the surface of the metal substrate, thereby producing a metal diaphragm.

[0111] Comparative Example 2

[0112] Preparation of coating mixture

[0113] In the same manner as in Example 1, a coating mixture was prepared.

[0114] Manufacturing of metal diaphragms

[0115] A titanium metal substrate (grade 1) was prepared, and the coating mixture prepared in Comparative Example 2 was applied to the surface of the titanium metal substrate by roller coating to a thickness of 1 μm. The metal substrate coated with the coating mixture was then placed in an oven and temporarily dried at 150° C. for 5 minutes, thereby forming a coating on the surface of the metal substrate.

[0116] Then, the metal substrate having the coating layer formed thereon was subjected to a first heat treatment of heating at 600° C. for 10 minutes in a low-oxygen atmosphere at 0.1 Pa to remove the organic binder of the coating layer, thereby manufacturing a metal diaphragm.

[0117] Comparative Example 3

[0118] Preparation of coating mixture

[0119] In the same manner as in Example 2, a coating mixture was prepared.

[0120] Manufacturing of metal diaphragms

[0121] A titanium metal substrate (grade 1) was prepared, and the coating mixture prepared in Comparative Example 3 was applied to the surface of the titanium metal substrate by roller coating to a thickness of 1 μm. The metal substrate coated with the coating mixture was then placed in an oven and temporarily dried at 150° C. for 5 minutes to form a coating on the surface of the metal substrate, thereby producing a metal diaphragm.

[0122] Comparative Example 4

[0123] Preparation of coating mixture

[0124] In the same manner as in Example 2, a coating mixture was prepared.

[0125] Manufacturing of metal diaphragms

[0126] A titanium metal substrate (grade 1) was prepared, and the coating mixture prepared in Comparative Example 4 was applied to the surface of the titanium metal substrate by roller coating to a thickness of 1 μm. The metal substrate coated with the coating mixture was then placed in an oven and temporarily dried at 150° C. for 5 minutes, thereby forming a coating on the surface of the metal substrate.

[0127] Then, the metal substrate having the coating layer formed thereon was subjected to a first heat treatment of heating at 600° C. for 10 minutes in a low-oxygen atmosphere at 0.1 Pa to remove the organic binder of the coating layer, thereby manufacturing a metal diaphragm.

[0128] Comparative Example 5

[0129] Preparation of coating mixture

[0130] In the same manner as in Example 3, a coating mixture was prepared.

[0131] Manufacturing of metal diaphragms

[0132] A titanium metal substrate (grade 1) was prepared, and the coating mixture prepared in Comparative Example 5 was applied to the surface of the titanium metal substrate by roll coating to a thickness of 1 μm. The metal substrate coated with the coating mixture was then placed in an oven and temporarily dried at 150° C. for 5 minutes to form a coating on the surface of the metal substrate, thereby producing a metal diaphragm.

[0133] Comparative Example 6

[0134] Preparation of coating mixture

[0135] In the same manner as in Example 3, a coating mixture was prepared.

[0136] Manufacturing of metal diaphragms

[0137] A titanium metal substrate (grade 1) was prepared, and the coating mixture prepared in Comparative Example 6 was applied to the surface of the titanium metal substrate by roller coating to a thickness of 1 μm. The metal substrate coated with the coating mixture was then placed in an oven and temporarily dried at 150° C. for 5 minutes, thereby forming a coating on the surface of the metal substrate.

[0138] Then, the metal substrate having the coating layer formed thereon was subjected to a first heat treatment of heating at 600° C. for 10 minutes in a low-oxygen atmosphere at 0.1 Pa to remove the organic binder of the coating layer, thereby manufacturing a metal diaphragm.

[0139] Comparative Example 7

[0140] Preparation of coating mixture

[0141] In the same manner as in Example 4, a coating mixture was prepared.

[0142] Manufacturing of metal diaphragms

[0143] A titanium metal substrate (grade 1) was prepared, and the coating mixture prepared in Comparative Example 7 was applied to the surface of the titanium metal substrate by roller coating to a thickness of 1 μm. The metal substrate coated with the coating mixture was then placed in an oven and temporarily dried at 150° C. for 5 minutes to form a coating on the surface of the metal substrate, thereby producing a metal diaphragm.

[0144] Comparative Example 8

[0145] Preparation of coating mixture

[0146] In the same manner as in Example 4, a coating mixture was prepared.

[0147] Manufacturing of metal diaphragms

[0148] A titanium metal substrate (grade 1) was prepared, and the coating mixture prepared in Comparative Example 8 was applied to the surface of the titanium metal substrate by roller coating to a thickness of 1 μm. The metal substrate coated with the coating mixture was then placed in an oven and temporarily dried at 150° C. for 5 minutes, thereby forming a coating on the surface of the metal substrate.

[0149] Then, the metal substrate having the coating layer formed thereon was subjected to a first heat treatment of heating at 600° C. for 10 minutes in a low-oxygen atmosphere at 0.1 Pa to remove the organic binder of the coating layer, thereby manufacturing a metal diaphragm.

[0150] Comparative Example 9

[0151] Preparation of coating mixture

[0152] In the same manner as in Example 5, a coating mixture was prepared.

[0153] Manufacturing of metal diaphragms

[0154] A titanium metal substrate (grade 1) was prepared, and the coating mixture prepared in Comparative Example 9 was applied to the surface of the titanium metal substrate by roll coating to a thickness of 1 μm. The metal substrate coated with the coating mixture was then placed in an oven and temporarily dried at 150° C. for 5 minutes to form a coating on the surface of the metal substrate, thereby producing a metal diaphragm.

[0155] Comparative Example 10

[0156] Preparation of coating mixture

[0157] In the same manner as in Example 5, a coating mixture was prepared.

[0158] Manufacturing of metal diaphragms

[0159] A titanium metal substrate (grade 1) was prepared, and the coating mixture prepared in Comparative Example 10 was applied to the surface of the titanium metal substrate by roller coating to a thickness of 1 μm. The metal substrate coated with the coating mixture was then placed in an oven and temporarily dried at 150° C. for 5 minutes, thereby forming a coating on the surface of the metal substrate.

[0160] Then, the metal substrate having the coating layer formed thereon was subjected to a first heat treatment of heating at 600° C. for 10 minutes in a low-oxygen atmosphere at 0.1 Pa to remove the organic binder of the coating layer, thereby manufacturing a metal diaphragm.

[0161] Experimental Example 1. Contact Resistance Evaluation

[0162] The contact resistance of the metal diaphragms manufactured in the examples and comparative examples was measured using a Zahner IM6 instrument using the four-wire current-voltage measurement principle. The results are shown in Table 1 below. Specifically, in constant current mode, the DC current was set to 5 A, the contact resistance measurement method was performed in the range of 10 kHz to 10 mHz, the measurement area amplitude was 0.5 A, and the electrode area was 25 cm 2 .

[0163] Experimental Example 2. Corrosion Current Evaluation

[0164] In a simulated environment of PEFC (polymer electrolyte fuel cell), the corrosion current of the metal diaphragms manufactured in the examples and comparative examples was measured using an EG&G273A tester. The results are shown in Table 1 below. Specifically, the metal diaphragms manufactured in the examples and comparative examples were placed in a 0.1N H2SO4+2ppm HF solution at 80°C and then bubbled with nitrogen (N2) for 1 hour. When the OCP (open circuit potential) was -0.25V, the corrosion current of the metal diaphragms was 0.1N H2SO4+2ppm HF solution at 80°C. SCE to 1.2V SCE The corrosion current is measured within the range of

[0165] Experimental Example 3. Adhesion Evaluation

[0166] In order to evaluate the adhesion of the coatings included in the metal separators manufactured in Examples and Comparative Examples, a tape was attached to the coating and then peeled off at 90° to confirm whether the coating was peeled off onto the tape. The results are shown in Table 1 below.

[0167] [Table 1]

[0168]

[0169]

[0170] As shown in Table 1 above, it is confirmed that the metal diaphragms manufactured in Examples 1 to 5 above have excellent electrical conductivity and corrosion resistance, and their contact resistance is 20 mΩ·cm 2 Or lower, corrosion current is 10μA / cm 2 or lower, and the coating adhesion is also excellent. In contrast, it was confirmed that the metal diaphragms manufactured in the above Comparative Examples 1, 3, 5 and 9 have excellent corrosion resistance, with a corrosion current of 10 μA / cm 2 Or lower, the coating adhesion is also very good, but the conductivity is low and the contact resistance is greater than 20mΩ·cm 2 .

[0171] Furthermore, it was confirmed that the metal diaphragms manufactured in Comparative Examples 2, 4, 6, 8, and 10 had excellent electrical conductivity and corrosion resistance, and their contact resistance was 20 mΩ·cm. 2Or lower, corrosion current is 10μA / m 2 or lower, but its coating adhesion is lower than that of the metal diaphragms manufactured in Examples 1 to 5 above.

[0172] Furthermore, it was confirmed that the metal diaphragm manufactured in the above comparative example 7 had excellent coating adhesion, but due to the contact resistance being greater than 20 mΩ·cm 2 , corrosion current is greater than 10μA / cm 2 , electrical conductivity and corrosion resistance are low.

[0173] In other words, it was confirmed that the metal separators manufactured in Examples 1 to 5 above were capable of simultaneously ensuring excellent electrical conductivity, corrosion resistance, and coating adhesion.

[0174] <Description of Reference Signs>

[0175] 100, 200: Metal diaphragm

[0176] 110, 210: Metal substrate

[0177] 120, 220: coating

[0178] 121, 221: conductive filler

[0179] 122, 222: Inorganic polymers

[0180] 223: Organic binder

[0181] H: Area of ​​the coating where the organic binder has been removed.

Claims

1. A metal diaphragm, comprising: Metal substrate; and A coating layer is formed on the surface of the metal substrate and comprises a conductive filler and an inorganic polymer. 2 . The metal diaphragm according to claim 1 , wherein the conductive filler comprises one or more selected from the group consisting of carbon black, carbon nanotubes, graphene, and carbon fibers. 3 . The metal separator according to claim 1 , wherein the inorganic polymer is a polymer containing a bond between a Group IVB transition metal element and an oxygen atom. 4 . The metal separator according to claim 1 , wherein the inorganic polymer is contained in the coating layer at 0.01 to 50 parts by weight relative to 100 parts by weight of the conductive filler. The metal diaphragm according to claim 1 , wherein the coating layer has a thickness of 10 nm to 5000 nm. The metal diaphragm according to claim 1 , wherein the coating has a relative humidity of 1 mΩ·cm 2 Up to 20mΩ·cm 2 contact resistance.

7. The metal diaphragm according to claim 1, wherein the coating has a thermal conductivity of 0.1 μA / cm 2 Up to 10μA / cm 2 of corrosion current.

8. A method for manufacturing a metal diaphragm, the metal diaphragm comprising a metal substrate and a coating, the coating being formed on a surface of the metal substrate and containing a conductive filler and an inorganic polymer, the method comprising: a mixing step of mixing the conductive filler and the organic binder to prepare a coating mixture; a coating step of coating the coating mixture on the surface of the metal substrate and temporarily drying the coating to form a coating; a first heat treatment step of performing a first heat treatment on the temporarily dried coating to remove an organic binder in the coating; and In the second heat treatment step, liquid metal-based organic matter is introduced into the region where the organic binder has been removed, and then a second heat treatment is performed to gel the liquid metal-based organic matter into an inorganic polymer. 9 . The method according to claim 8 , wherein the conductive filler is contained in the coating mixture at 40 to 600 parts by weight relative to 100 parts by weight of the organic binder. 10 . The method according to claim 8 , wherein the temporary drying is performed at a temperature of 80° C. to 200° C. for 10 seconds to 60 minutes. 11 . The method according to claim 8 , wherein the first heat treatment is performed at 250° C. to 900° C. for 10 seconds to 24 hours under a pressure of 0.05 Pa to 0.5 Pa.

12. The method according to claim 8, further comprising: The coating thickness adjustment step is used to reduce the thickness of the coating from which the organic binder has been removed.

13. The method according to claim 8, wherein the liquid metal-based organic compound exists in a state where the metal-based organic compound represented by the following chemical formula 1 is dispersed in a liquid dispersion medium: [Chemical Formula 1] M(OR)4, In the above Chemical Formula 1, M is a Group IVB transition metal element, and R is a linear or branched alkyl group having 1 to 6 carbon atoms.

14. The method according to claim 8, wherein The liquid metal-based organic matter is introduced into the region where the organic binder has been removed by immersing the metal substrate having the coating layer where the organic binder has been removed in the liquid metal-based organic matter for 1 second to 10 minutes. 15 . The method according to claim 8 , wherein the second heat treatment is performed at 250° C. to 900° C. for 10 seconds to 24 hours in a vacuum atmosphere.

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