Metal separator and its manufacturing method

Abstract

TECHNICAL FIELD The present application relates to a metal separator and a manufacturing method thereof. The metal separator and manufacturing method thereof of the present application not only have excellent electrical conductivity and corrosion resistance, but also have excellent adhesion of a coating layer.

Description

[Technical Field]

[0001] The present application relates to a metal separator plate and a method for manufacturing the same. [Background technology]

[0002] In recent years, powertrains have been shifting from internal combustion engines (ICEs) to electric vehicles (EVs) and hydrogen fuel cell vehicles (FCEVs) in response to global warming. Fuel cells used in hydrogen fuel cell vehicles (FCEVs) are not only used to power industrial, residential, and vehicle applications, but also to power small electronic devices such as portable devices. As a highly efficient, clean energy source, their scope of use is gradually expanding in terms of both energy conservation and environmental protection.

[0003] A fuel cell is a type of power generation device that converts the chemical energy of fuel into electrical energy through an electrochemical reaction in a stack. It generates electricity using the energy generated during the reaction between hydrogen and oxygen. Specifically, a fuel cell can use hydrogen gas as fuel and generate hydrogen ions and electrons through an oxidation reaction of the hydrogen gas. The generated hydrogen ions and electrons then undergo an electrochemical reaction with oxygen in the air to produce water, and electrical energy is generated from the flow of electrons.

[0004] Such a hydrogen fuel cell is composed of a separator plate, a diffusion layer (GDL), and a membrane electrode assembly coated with catalyst powder. Hydrogen fuel cells can theoretically generate a voltage of 1.229 V, but due to various limitations such as the inherent characteristics of the above-mentioned components and the characteristics between components, the operating voltage is 0.6 V to 0.8 V.

[0005] Among these components, the separator plate must have various functions, such as structural support for the gas diffusion layer, collection and transmission of generated current, transport and removal of reactant gas, and transport of cooling water for removing reaction heat, and therefore must have excellent electrical conductivity, thermal conductivity, gas tightness, chemical stability, etc. That is, the separator plate must have a structure in which hydrogen ions dissolve in water to form an acid, so it must be corrosion-resistant, and it must also have electrical conductivity because hydrogen and oxygen react to release electrons and the generated electrons must be transported through the separator plate.

[0006] The US Department of Energy (DOE), which is at the center of environmental energy research, requires separator materials that can withstand pH levels of 4 or higher. Actual corrosion tests have also been conducted at pH levels of 1 to 3 and 0.6V. vs SCE In such an environment, materials are kept at the same potential of 0.6V to ensure corrosion resistance. vs SCE at 10 μA / cm 2 It must exhibit a current density of 20 mΩ cm under a pressure of 133 N / m. 2 The material must exhibit an interfacial contact resistance of 100 S / cm or less. 2 or more, or contact resistance 20mΩ·cm 2 The following is required:

[0007] For metal materials, the initial 4 S / cm 2 However, metal materials have the disadvantage of lowering electrical conductivity due to corrosion. In addition, graphite has concerns about cracking during processing and hydrogen permeability, and it is difficult to control the thickness downward. In addition, great care is required during the process, which limits the weight reduction and economic efficiency.

[0008] To solve this problem, Patent Document 1 (Korean Patent No. 0839193) uses a metal separator in which a coating layer containing an organic binder and carbon particles is formed on a base material made of a metal material. This metal separator can ensure corrosion resistance, but has the disadvantage of low electrical conductivity due to the organic binder.

[0009] To solve this problem, the organic binder was removed to ensure electrical conductivity, but the removal of the organic binder resulted in a very low adhesion of the coating layer, which was inconvenient as the coating layer was easily removed even with low shear stress. Therefore, to solve this problem, a metal separator plate with excellent electrical conductivity, corrosion resistance, and adhesion, and a method for manufacturing the same, is needed. Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present application is to provide a metal separator having excellent electrical conductivity and corrosion resistance as well as excellent adhesion of a coating layer, and a method for manufacturing the same. [Means for solving the problem]

[0011] To solve the above problems, the metal separator of the present application comprises a metal base material; and a coating layer formed on the surface of the metal base material, the coating layer including a conductive filler and an inorganic polymer.

[0012] The conductive filler may include one or more selected from carbon black, carbon nanotubes, graphene, and carbon fibers.

[0013] The inorganic polymer may also be a polymer containing a bond between a Group IVB transition metal element and an oxygen atom.

[0014] Furthermore, the inorganic polymer may be contained 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.

[0015] The coating layer may have a thickness of 10 nm to 5000 nm.

[0016] Furthermore, the coating layer has a contact resistance of 1 mΩ·cm 2 ~20mΩ·cm 2 It could be.

[0017] The coating layer has a corrosion current of 0.1 μA / cm 2 ~10μA / cm 2 It could be.

[0018] Furthermore, the present application relates to a method for manufacturing a metal separator plate, which includes a metal base material and a coating layer formed on the surface of the metal base material and containing a conductive filler and an inorganic polymer, and includes the steps of: a mixing step of mixing a conductive filler and an organic binder to prepare a coating mixture; a coating step of coating the surface of the metal base material with the coating mixture and pre-drying to form a coating layer; a primary heat treatment step of performing a primary heat treatment on the pre-dried coating layer to remove the organic binder from the coating layer; and a secondary heat treatment step of mixing a liquid metal-based organic material into the area from which the organic binder has been removed, followed by a secondary heat treatment to gel the liquid metal-based organic material into the inorganic polymer.

[0019] The conductive filler may be included in the coating mixture in an amount of 40 to 600 parts by weight based on 100 parts by weight of the organic binder.

[0020] Furthermore, the preliminary drying can be carried out at a temperature of 80° C. to 200° C. for 10 seconds to 60 minutes.

[0021] The primary heat treatment can be carried out under a pressure of 0.05 Pa to 0.5 Pa at a temperature of 250° C. to 900° C. for 10 seconds to 24 hours.

[0022] Furthermore, the method for manufacturing the metal separator may further include a step of adjusting the thickness of the coating layer by removing the organic binder.

[0023] In addition, the liquid metal-based organic material may be present in a state where the metal-based organic material represented by the following Chemical Formula 1 is dispersed in a liquid dispersion medium.

[0024] [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.

[0025] Furthermore, mixing a liquid metal-based organic material into the region from which the organic binder has been removed is carried out by immersing the metal base material, on the surface of which a coating layer from which the organic binder has been removed, in the liquid metal-based organic material, and the immersion can be carried out for 1 second to 10 minutes.

[0026] The secondary heat treatment can be carried out in a vacuum atmosphere at 250° C. to 900° C. for 10 seconds to 24 hours. [Effects of the Invention]

[0027] The metal separator and the manufacturing method thereof of the present application not only have excellent electrical conductivity and corrosion resistance, but also have excellent adhesion of the coating layer. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a diagram illustrating an exemplary metal separator plate according to one embodiment of the present application. [Figure 2] FIG. 2 is a diagram illustrating an example of a metal separator plate that has undergone a coating step, for explaining the coating step according to an embodiment of the present application. [Figure 3] FIG. 3 is a diagram illustrating an example of a metal separator plate that has undergone a primary heat treatment step, for explaining the primary heat treatment step according to an embodiment of the present application. [Figure 4]FIG. 4 is a diagram illustrating an example of a metal separator plate that has undergone a secondary heat treatment step, for explaining the secondary heat treatment step according to an embodiment of the present application. [Figure 5] FIG. 5 is a 10,000x magnification image of the surface of the metal separator plate after the coating step in Example 1, taken with a scanning electron microscope. [Figure 6] FIG. 6 is a 10,000x magnification image taken with a scanning electron microscope of the surface of the metal separator plate that has undergone the primary heat treatment step in Example 1. [Figure 7] FIG. 7 is a 10,000x magnification image taken with a scanning electron microscope of the surface of the metal separator plate that has undergone the secondary heat treatment step in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0029] The metal separator of the present application will be described below with reference to the accompanying drawings, which are for illustrative purposes only and are not intended to limit the scope of the present application.

[0030] 1 is a diagram illustrating an example of a metal separator according to an embodiment of the present application. As shown in FIG. 1, the metal separator 100 of the present application includes a metal base material 110 and a coating layer 120. The metal separator 100 of the present application not only has excellent electrical conductivity and corrosion resistance, but also has excellent adhesion of the coating layer 120. In this specification, the "adhesion of the coating layer" refers to the strength with which the coating layer adheres to the metal base material.

[0031] The metal base material 110 is a metal material used in metal separators for fuel cells. The type of the metal base material 110 is not particularly limited, and any metal base material used in metal separators for fuel cells can be used without limitation. For example, the metal base material 110 can be made of titanium, aluminum, magnesium, copper, stainless steel, or an alloy thereof. Specifically, the metal base material 110 can be made of SUS 300 series stainless steel. The metal separator 100 has excellent electrical conductivity due to the inclusion of the metal base material 110.

[0032] The coating layer 120 is a layer coated on the surface of the metal base material 110 and includes a conductive filler 121 and an inorganic polymer 122. The coating layer 120 is formed on the surface of the metal base material 110, thereby improving the corrosion resistance of the metal base material 110 and also improving the adhesion of the coating layer 120. In this specification, the term "surface" refers to a surface located on one side, both sides, or all sides of the metal base material.

[0033] The conductive filler 121 is a material having electrical conductivity. For example, the conductive filler 121 may include at least one selected from the group consisting of carbon black, carbon nanotubes, graphene, and carbon fibers. By including the conductive filler 121 in the coating layer 120, the electrical conductivity of the metal separator 100 may be improved.

[0034] For example, 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. The conductive filler 121 having the above particle size can improve electrical conductivity.

[0035] The inorganic polymer 122 is a polymer having an inorganic material 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 rutherfordium (Rf). That is, the inorganic polymer 122 may be titanium sol-gel, zirconium sol-gel, hafnium sol-gel, or rutherfordium sol-gel. By including the inorganic polymer 122 in the coating layer 120, the metal separator 100 not only has excellent electrical conductivity and corrosion resistance, but also has excellent adhesion of the coating layer 120.

[0036] For example, the inorganic polymer 122 may be included in the coating layer 110 in an amount of 0.01 to 50 parts by weight, based on 100 parts by weight of the conductive filler 121. Specifically, the inorganic polymer 122 may be included in the coating layer 110 in an amount of 0.05 to 40 parts by weight, or 0.1 to 30 parts by weight, based on 100 parts by weight of the conductive filler 121. By including the inorganic polymer 122 in the coating layer 110 in the above amounts, the metal separator 100 not only has excellent electrical conductivity and corrosion resistance, but also has excellent adhesion of the coating layer 120.

[0037] As another example, the coating layer 120 may have a thickness of 10 nm to 5000 nm. Specifically, the upper limit of the thickness of the coating layer 120 may be 4000 nm or less, 3000 nm or less, 2000 nm or less, or 1000 nm or less. By having the coating layer 120 within the above thickness range, the coating layer 120 can be stabilized without losing electrical conductivity. In contrast, if the coating layer 120 exceeds the above thickness range, many pores may be formed inside the coating layer 120, causing many defects, which may result in reduced electrical conductivity and corrosion resistance.

[0038] In addition, the coating layer 120 has a contact resistance of 1 mΩ·cm.2 ~20mΩ·cm 2 Specifically, the contact resistance of the coating layer 120 may be up to 15 mΩ·cm. 2 or less, or 10 mΩ·cm 2 The coating layer 120 has the above-described contact resistance, thereby providing the metal separator 100 with excellent electrical conductivity.

[0039] Furthermore, the coating layer 120 has a corrosion current of 0.1 μA / cm 2 ~10μA / cm 2 Specifically, the upper limit of the corrosion current of the coating layer 120 is 9 μA / cm 2 Below, 8μA / cm 2 or less than 7μA / cm 2 The coating layer 120 has the above-mentioned corrosion current, thereby providing the metal separator 100 with excellent corrosion resistance.

[0040] The present application also relates to a method for manufacturing a metal separator plate. The method for manufacturing the metal separator plate relates to a method for manufacturing the metal separator plate described above, and the details of the metal separator plate described below are omitted because they are the same as those described above.

[0041] The method for manufacturing a metal separator of the present application includes a mixing step, a coating step, a primary heat treatment step, and a secondary heat treatment step, and the method for manufacturing a metal separator of the present application not only has excellent electrical conductivity and corrosion resistance, but also has excellent adhesion of the coating layer.

[0042] The mixing step is a step of preparing a coating mixture for coating the surface of a metal base material, and is performed by mixing a conductive filler and an organic binder, that is, the conductive filler may be dispersed in the organic binder through the mixing step.

[0043] For example, the conductive filler may be included in the coating mixture in an amount of 40 to 600 parts by weight, based on 100 parts by weight of the organic binder. Specifically, the conductive filler may be included in the coating mixture in an amount of 60 to 540 parts by weight, 80 to 480 parts by weight, or 100 to 420 parts by weight, based on 100 parts by weight of the organic binder. The conductive filler included in the coating mixture in the above amounts provides excellent electrical conductivity for the metal separator. Furthermore, the organic binder may be included in the coating mixture in an amount of 16 to 250 parts by weight, based on 100 parts by weight of the conductive filler. Specifically, the organic binder may be included in the coating mixture in an amount of 18 to 167 parts by weight, 20 to 125 parts by weight, or 23 to 100 parts by weight, based on 100 parts by weight of the conductive filler. By including the organic binder in the coating composition in the above amounts, the conductive filler can be coated on the surface of the metal substrate, thereby improving the corrosion resistance of the metal separator.

[0044] The organic binder may be a polymer binder that thermally decomposes at a temperature of 300°C or higher. For example, the organic binder may include an acrylic resin, a modified alkyd resin, a melamine resin, or a mixture thereof. Specifically, the modified alkyd resin may be a phenol-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 first heat treatment step described below.

[0045] 2 is a diagram illustrating a metal separator plate having undergone a coating step to explain the coating step according to one embodiment of the present application. As shown in FIG. 2, the coating step is a step of forming a coating layer 220 on the surface of the metal base material 210 using the coating mixture prepared in the mixing step. The coating step is performed by coating the surface of the metal base material 210 with the coating mixture and pre-drying it. By including the coating step, the method for manufacturing the metal separator plate can coat the surface of the metal base material 210 with the organic binder 223, thereby coating the conductive filler 221.

[0046] The coating mixture may be applied by spraying or physical vapor deposition.

[0047] Furthermore, when the coating mixture is applied, the coating thickness may be 0.01 μm to 20 μm, specifically 0.02 μm to 18 μm, 0.03 μm to 15 μm, 0.04 μm to 13 μm, or 0.05 μm to 10 μm. By applying the coating mixture to the above-mentioned thickness, the corrosion resistance of the metal separator can be improved.

[0048] The pre-drying refers to touch-drying to the extent that the coating mixture does not stick to other devices or hands, and is carried out for 10 seconds to 60 minutes at a temperature of 80°C to 200°C. Specifically, the pre-drying is carried out 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, the pre-drying is carried out in an oven.

[0049] 3 is a diagram illustrating a metal separator plate that has undergone a first heat treatment step to explain the first heat treatment step according to one embodiment of the present application. As shown in FIG. 3, the first heat treatment step is a heat treatment step for removing the organic binder in the coating layer 220, and is performed by performing the first heat treatment on the pre-dried coating layer 220. In the method for manufacturing the metal separator plate, the organic binder in the coating layer 220 can be thermally decomposed and removed by performing the first heat treatment step, thereby forming a region H in the coating layer 220 from which the organic binder has been removed.

[0050] For example, the primary heat treatment is performed at 250°C to 900°C under a pressure of 0.05 Pa to 0.5 Pa for 10 seconds to 24 hours. Specifically, the primary heat treatment is performed at 300°C to 800°C, 400°C to 700°C, or 500°C to 600°C under a pressure of 0.4 Pa or less, 0.3 Pa or less, 0.2 Pa or less, or 0.1 Pa or less, 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 primary heat treatment under the above conditions, the organic binder in the coating layer 220 can be completely removed. Here, the pressure refers to the oxygen partial pressure of a low-oxygen atmosphere. By carrying out the primary heat treatment in the low-oxygen atmosphere, it is possible to prevent oxidation of the metal base material and to prevent an oxide layer from being formed on the metal base material.

[0051] In another example, the method for manufacturing a metal separator further includes a thickness adjusting step. The thickness adjusting step is a step of adjusting the thickness of the coating layer from which the organic binder has been removed after the first heat treatment step, and is performed to reduce the thickness of the coating layer from which the organic binder has been removed. Specifically, the thickness adjusting step is performed by repeatedly attaching and detaching a tape having an adhesive formed on one surface to the surface of the coating layer from which the organic binder has been removed. By further including the thickness adjusting step, 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.

[0052] 4 is a diagram illustrating a metal separator plate that has undergone a second heat treatment step to explain the second heat treatment step according to one embodiment of the present disclosure. As shown in FIG. 4, the second heat treatment step involves mixing a liquid metal-based organic material into the area of ​​the coating layer from which the organic binder was removed by the first heat treatment, and then performing heat treatment to gel the liquid metal-based organic material into an inorganic polymer 222. By performing the second heat treatment step, the method for manufacturing a metal separator plate can form an inorganic polymer 222 in the area of ​​the coating layer from which the organic binder was removed, thereby providing excellent electrical conductivity and corrosion resistance as well as excellent adhesion of the coating layer 220.

[0053] The liquid metal-based organic material may be present in a state where a metal-based organic material represented by the following Chemical Formula 1 is dispersed in a liquid dispersion medium.

[0054] [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.

[0055] Specifically, the Group IVB transition metal element may be titanium (Ti), zirconium (Zr), hafnium (Hf), or rutherfordium (Rf). By including the Group IVB transition metal element in the liquid metal-based organic material, the metal separator 200 has excellent conductivity.

[0056] 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, 1 to 4, or 1 to 3 carbon atoms. Specific examples of R include a linear alkyl group such as ethyl, methyl, propyl, butyl, pentyl, or hexyl, or a branched alkyl group such as n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 1-methylbutyl, 1-ethylbutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, or 4-methyl-2-pentyl.

[0057] For example, the metal-based organic material represented by Chemical Formula 1 above can 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).

[0058] As another example, the metal-based organic material can be charged with an inorganic acid. For example, the inorganic acid can be nitric acid (HNO), sulfuric acid (HSO), hydrochloric acid (HCl), phosphoric acid (HPO), perchloric acid (HClO), hypochlorous acid (HClO), hydrofluoric acid (HF), or acetic acid (CHCOOH). By charging the metal-based organic material with the inorganic acid, the metal contained in the metal-based organic material can be stabilized.

[0059] The type of the dispersion medium may be any dispersion medium known in the art without any particular limitation. By using the above-mentioned type of dispersion medium, an inorganic oligomer can be formed.

[0060] For example, the liquid metal-based organic material may have a solid content of 1% to 5%, more specifically, 1.5% to 4%, or 2% to 3%. When the solid content of the liquid metal-based organic material satisfies the above range, the liquid metal-based organic material not only has excellent electrical conductivity and corrosion resistance, but also has excellent adhesion of the coating layer.

[0061] The liquid metal-based organic material may have a pH of more than 0 to 4, specifically 0.5 to 3, or 1 to 2. When the pH of the liquid metal-based organic material satisfies the above range, the metal contained in the metal-based organic material can be stabilized.

[0062] As an example, the liquid metal-based organic material is mixed into the region from which the organic binder has been removed by immersing a metal base material, on the surface of which a coating layer from which the organic binder has been removed is to be formed, in the liquid metal-based organic material.

[0063] For example, the liquid metal-based organic material can be mixed into the region from which the organic binder has been removed by immersing the metal base material, on the surface of which the coating layer from which the organic binder has been removed, in the liquid metal-based organic material. The immersion is carried out for 1 second to 10 minutes. Specifically, the immersion is carried out for 1 second to 8 minutes, or 1 second to 5 minutes. By carrying out the immersion for the aforementioned time, the liquid metal-based organic material can be mixed into all regions of the coating layer from which the organic binder has been removed.

[0064] The secondary heat treatment is performed in a vacuum atmosphere at 250°C to 900°C for 10 seconds to 24 hours. Specifically, the secondary heat treatment is 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 secondary heat treatment under the above conditions, the liquid metal-based organic material mixed in the region of the coating layer from which the organic binder has been removed can be gelled into the inorganic polymer 222. In this specification, a "vacuum atmosphere" refers to a working environment having a vacuum state. For example, the pressure of the vacuum atmosphere can be 0.0001 Pa to 0.01 Pa. By carrying out the secondary heat treatment in the vacuum atmosphere described above, the liquid metal-based organic material can be gelled into the inorganic polymer 222, and the lattice of the titanium dioxide film that may be generated during the gelling process can be twisted, thereby improving electrical conductivity.

[0065] The present application will be described in more detail below 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.

[0066] Example 1 Preparation of the coating mixture Carbon black with a particle size of 50 nm was used as the conductive filler, and acrylic resin was used as the organic binder. The conductive filler and the organic binder were diluted in an isopropyl alcohol organic solvent in a 5:5 ratio to prepare a coating mixture.

[0067] Manufacturing of metal separator plates A titanium metal base material (Grade 1) was prepared, and the surface of the titanium metal base material was roll-coated with the coating mixture prepared in Example 1 to a thickness of 1 μm. The metal base material coated with the coating mixture was then placed in an oven and pre-dried at a temperature of 150°C for 5 minutes to form a coating layer on the surface of the metal base material. The surface of the metal base material with the coating layer formed was photographed, and the results are shown in Figure 5.

[0068] The metal base material with the coating layer formed thereon was then subjected to a primary heat treatment in which it was heated at 600°C for 10 minutes in a low-oxygen atmosphere of 0.1 Pa to remove the organic binder from the coating layer. At this time, the coating layer from which the organic binder had been removed was photographed, and the results are shown in Figure 6.

[0069] The metal substrate, on which the organic binder had been removed and the coating layer formed on its surface, was then immersed for 5 minutes in a liquid metal-based organic material prepared by dispersing titanium tetraisopropoxide in a dispersion medium, having a solids content of 1%, and charged with nitric acid and a pH of 2. The liquid metal-based organic material was then mixed into the area from which the organic binder had been removed. The metal substrate, on which the coating layer containing the liquid metal-based organic material had been mixed, was then subjected to a secondary heat treatment at 600°C for 10 minutes in a vacuum atmosphere of 0.01 Pa. This gelled the liquid metal-based organic material into an inorganic polymer, TiO polymer, to produce a metal separator plate with a 1 μm-thick coating layer formed on the surface of the metal substrate. The coating layer formed on the surface of the metal substrate of the metal separator was photographed, and the results are shown in Figure 7.

[0070] Example 2 Preparation of the coating mixture 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.

[0071] Manufacturing of metal separators A metal separator was manufactured in the same manner as in Example 1, except that the coating mixture prepared in Example 2 was used.

[0072] Example 3 Preparation of the coating mixture 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.

[0073] Manufacturing of metal separator plates A metal separator was manufactured in the same manner as in Example 1, except that the coating mixture prepared in Example 3 was used.

[0074] Example 4 Preparation of the coating mixture 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.

[0075] Manufacturing of metal separator plates A metal separator was manufactured in the same manner as in Example 1, except that the coating mixture prepared in Example 4 was used.

[0076] Example 5 Preparation of the coating mixture Carbon black with a particle size of 50 nm was used as the conductive filler, and phenol-modified alkyd resin was used as the organic binder. The conductive filler and the organic binder were diluted in an isopropyl alcohol organic solvent in a ratio of 6:4 to prepare a coating mixture.

[0077] Manufacturing of metal separator plates A metal separator was manufactured in the same manner as in Example 1, except that the coating mixture prepared in Example 5 was used.

[0078] Comparative Example 1 Preparation of the coating mixture The coating mixture was prepared in the same manner as in Example 1.

[0079] Manufacturing of metal separators A titanium metal base material (Grade 1) was prepared, and the surface of the titanium metal base material was roll-coated with the coating mixture prepared in Comparative Example 1 to a thickness of 1 μm. The metal base material coated with the coating mixture was then placed in an oven and pre-dried at a temperature of 150° C. for 5 minutes to form a coating layer on the surface of the metal base material, thereby producing a metal separator.

[0080] Comparative Example 2 Preparation of the coating mixture The coating mixture was prepared in the same manner as in Example 1.

[0081] Manufacturing of metal separators A titanium metal base material (Grade 1) was prepared, and the surface of the titanium metal base material was roll-coated with the coating mixture prepared in Comparative Example 2 to a thickness of 1 μm. The metal base material coated with the coating mixture was then placed in an oven and pre-dried at a temperature of 150° C. for 5 minutes to form a coating layer on the surface of the metal base material.

[0082] Thereafter, the metal substrate on which the coating layer was formed was subjected to a primary heat treatment in a low-oxygen atmosphere of 0.1 Pa at 600°C for 10 minutes to remove the organic binder in the coating layer, thereby producing a metal separator.

[0083] Comparative Example 3 Preparation of the coating mixture The coating mixture was prepared in the same manner as in Example 2.

[0084] Manufacturing of metal separators A titanium metal base material (Grade 1) was prepared, and the surface of the titanium metal base material was roll-coated with the coating mixture prepared in Comparative Example 3 to a thickness of 1 μm. The metal base material coated with the coating mixture was then placed in an oven and pre-dried at a temperature of 150° C. for 5 minutes to form a coating layer on the surface of the metal base material, thereby producing a metal separator.

[0085] Comparative Example 4 Preparation of the coating mixture The coating mixture was prepared in the same manner as in Example 2.

[0086] Manufacturing of metal separators A titanium metal base material (Grade 1) was prepared, and the surface of the titanium metal base material was roll-coated with the coating mixture prepared in Comparative Example 4 to a thickness of 1 μm. Then, the metal base material coated with the coating mixture was placed in an oven and pre-dried at a temperature of 150° C. for 5 minutes to form a coating layer on the surface of the metal base material.

[0087] Thereafter, the metal substrate on which the coating layer was formed was subjected to a primary heat treatment in a low-oxygen atmosphere of 0.1 Pa at 600°C for 10 minutes to remove the organic binder in the coating layer, thereby producing a metal separator.

[0088] Comparative Example 5 Preparation of the coating mixture The coating mixture was prepared in the same manner as in Example 3.

[0089] Manufacturing of metal separators A titanium metal base material (Grade 1) was prepared, and the surface of the titanium metal base material was roll-coated with the coating mixture prepared in Comparative Example 5 to a thickness of 1 μm. The metal base material coated with the coating mixture was then placed in an oven and pre-dried at a temperature of 150° C. for 5 minutes to form a coating layer on the surface of the metal base material, thereby producing a metal separator.

[0090] Comparative Example 6 Preparation of the coating mixture The coating mixture was prepared in the same manner as in Example 3.

[0091] Manufacturing of metal separators A titanium metal base material (Grade 1) was prepared, and the surface of the titanium metal base material was roll-coated with the coating mixture prepared in Comparative Example 6 to a thickness of 1 μm. Then, the metal base material coated with the coating mixture was placed in an oven and pre-dried at a temperature of 150° C. for 5 minutes to form a coating layer on the surface of the metal base material.

[0092] Thereafter, the metal substrate on which the coating layer was formed was subjected to a primary heat treatment in a low-oxygen atmosphere of 0.1 Pa at 600°C for 10 minutes to remove the organic binder in the coating layer, thereby producing a metal separator.

[0093] Comparative Example 7 Preparation of the coating mixture The coating mixture was prepared in the same manner as in Example 4.

[0094] Manufacturing of metal separators A titanium metal base material (Grade 1) was prepared, and the surface of the titanium metal base material was roll-coated with the coating mixture prepared in Comparative Example 7 to a thickness of 1 μm. The metal base material coated with the coating mixture was then placed in an oven and pre-dried at a temperature of 150° C. for 5 minutes to form a coating layer on the surface of the metal base material, thereby producing a metal separator.

[0095] Comparative Example 8 Preparation of the coating mixture The coating mixture was prepared in the same manner as in Example 4.

[0096] Manufacturing of metal separators A titanium metal base material (Grade 1) was prepared, and the surface of the titanium metal base material was roll-coated with the coating mixture prepared in Comparative Example 8 to a thickness of 1 μm. Then, the metal base material coated with the coating mixture was placed in an oven and pre-dried at a temperature of 150° C. for 5 minutes to form a coating layer on the surface of the metal base material.

[0097] Thereafter, the metal substrate on which the coating layer was formed was subjected to a primary heat treatment in a low-oxygen atmosphere of 0.1 Pa at 600°C for 10 minutes to remove the organic binder in the coating layer, thereby producing a metal separator.

[0098] Comparative Example 9 Preparation of the coating mixture The coating mixture was prepared in the same manner as in Example 5.

[0099] Manufacturing of metal separators A titanium metal base material (Grade 1) was prepared, and the surface of the titanium metal base material was roll-coated with the coating mixture prepared in Comparative Example 9 to a thickness of 1 μm. The metal base material coated with the coating mixture was then placed in an oven and pre-dried at a temperature of 150° C. for 5 minutes to form a coating layer on the surface of the metal base material, thereby producing a metal separator.

[0100] Comparative Example 10 Preparation of the coating mixture The coating mixture was prepared in the same manner as in Example 5.

[0101] Manufacturing of metal separators A titanium metal base material (Grade 1) was prepared, and the surface of the titanium metal base material was roll-coated with the coating mixture prepared in Comparative Example 10 to a thickness of 1 μm. Then, the metal base material coated with the coating mixture was placed in an oven and pre-dried at a temperature of 150° C. for 5 minutes to form a coating layer on the surface of the metal base material.

[0102] Thereafter, the metal substrate on which the coating layer was formed was subjected to a primary heat treatment in a low-oxygen atmosphere of 0.1 Pa at 600°C for 10 minutes to remove the organic binder in the coating layer, thereby producing a metal separator.

[0103] Experimental example 1: Evaluation of contact resistance The contact resistance of the metal separators manufactured in the examples and comparative examples was measured using a Zahner IM6 device based on the four-wire current-voltage measurement principle, and the results are shown in Table 1 below. Specifically, the contact resistance was measured in a constant current mode with an amplitude of 0.5 A in the measurement area and a voltage of 25 cm. 2 The DC current was 5 A with an electrode area of ​​10 kHz to 10 mHz.

[0104] Experimental Example 2: Evaluation of corrosion current The corrosion current of the metal separators prepared in the examples and comparative examples was measured using an EG&G 273A measuring device under a simulated environment of a PEFC (Polymer Electrolyte Fuel Cell), and the results are shown in Table 1. Specifically, the corrosion current was measured by placing the metal separators prepared in the examples and comparative examples in a 0.1 N H2SO4 + 2 ppm HF solution at 80°C, bubbling nitrogen (N2) for 1 hour, and then measuring the corrosion current at an OCP (Open Circuit Potential) of -0.25 V. SCE ~1.2 V SCE was measured in the range.

[0105] Experimental Example 3: Evaluation of Adhesion To evaluate the adhesion of the coating layer included in the metal separators manufactured in the Examples and Comparative Examples, a tape was attached to the coating layer and then peeled off at 90°C to check whether the coating layer peeled off from the tape. The results are shown in Table 1 below.

[0106] [Table 1]

[0107] As shown in Table 1, the metal separators manufactured in Examples 1 to 5 had a resistivity of 20 mΩ·cm 2 Contact resistance of less than 10μA / cm 2 In contrast, the metal separators manufactured in Comparative Examples 1, 3, 5, and 9 had a corrosion current of 10 μA / cm or less, indicating that they have excellent electrical conductivity and corrosion resistance, as well as excellent adhesion of the coating layer. 2 It has a corrosion current of 20mΩ·cm or less, has excellent corrosion resistance, and has excellent adhesion of the coating layer. 2 It was confirmed that the contact resistance was excessive and the electrical conductivity was low.

[0108] In addition, the metal separators manufactured in Comparative Examples 2, 4, 6, 8, and 10 had a resistivity of 20 mΩ·cm 2 Contact resistance of less than 10μA / cm 2Although the metal separators had the following corrosion currents and were excellent in electrical conductivity and corrosion resistance, it was confirmed that the adhesion of the coating layer was lower than that of the metal separators manufactured in Examples 1 to 5.

[0109] Furthermore, although the metal separator produced in Comparative Example 7 has excellent adhesion of the coating layer, it has a resistance of 20 mΩ·cm 2 Contact resistance exceeding 10μA / cm 2 It was confirmed that the material had an excessive corrosion current, and had low electrical conductivity and corrosion resistance.

[0110] That is, it was confirmed that the metal separators manufactured in Examples 1 to 5 were able to simultaneously ensure excellent electrical conductivity, corrosion resistance, and adhesion of the coating layer. [Explanation of symbols]

[0111] 100, 200: Metal separation plate 110, 210: Metal base material 120, 220: Coating layer 121, 221: Conductive filler 122, 222: inorganic polymers 223: Organic binder H: Region of the coating layer from which the organic binder has been removed

Claims

1. a metal base material; and The metal separator includes a coating layer formed on the surface of the metal base material, the coating layer including a conductive filler and an inorganic polymer.

2. The metal separator of claim 1 , wherein the conductive filler comprises at least one selected from the group consisting of carbon black, carbon nanotubes, graphene, and carbon fibers.

3. 2. 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. 2. The metal separator of claim 1, wherein the inorganic polymer coating layer contains 0.01 to 50 parts by weight of conductive filler, based on 100 parts by weight of the conductive filler.

5. The metal separator according to claim 1, wherein the coating layer has a thickness of 10 nm to 5000 nm.

6. The coating layer has a contact resistance of 1 mΩ·cm ２ ~20mΩ cm ２ 2. The metal separator plate of claim 1, wherein:

7. The coating layer has a corrosion current of 0.1 μA / cm ２ ~10 μA / cm ２ 2. The metal separator according to claim 1, wherein

8. a metal base material; and The present invention relates to a method for manufacturing a metal separator, which comprises manufacturing a metal separator including a coating layer formed on the surface of the metal base material and including a conductive filler and an inorganic polymer, a mixing step of mixing a conductive filler and an organic binder to produce a coating mixture; a coating step of coating the coating mixture on the surface of a metal base material and temporarily drying the mixture to form a coating layer; a primary heat treatment step of performing a primary heat treatment on the temporarily dried coating layer to remove the organic binder in the coating layer; and A method for manufacturing a metal separator, comprising a secondary heat treatment step of mixing a liquid metal-based organic material into the area from which the organic binder has been removed, and then performing a secondary heat treatment to gel the liquid metal-based organic material into an inorganic polymer.

9. The method of claim 8, wherein the conductive filler is contained in the coating mixture in an amount of 40 to 600 parts by weight based on 100 parts by weight of the organic binder.

10. The method for manufacturing a metal separator according to claim 8, wherein the pre-drying is performed at a temperature of 80°C to 200°C for 10 seconds to 60 minutes.

11. The method for manufacturing a metal separator according to claim 8, wherein the primary heat treatment is performed under a pressure of 0.05 Pa to 0.5 Pa at 250° C. to 900° C. for 10 seconds to 24 hours.

12. The method for manufacturing a metal separator according to claim 8, further comprising a step of adjusting the thickness of the coating layer by reducing the thickness of the coating layer from which the organic binder has been removed.

13. The method for manufacturing a metal separator according to claim 8, wherein the liquid metal-based organic material is a metal-based organic material represented by the following Chemical Formula 1, which is present in a state of being dispersed in a liquid dispersion medium: [Chemical formula 1] M(OR) ４ In the above 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. 9. The method for manufacturing a metal separator according to claim 8, wherein the mixing of the liquid metal-based organic material into the region from which the organic binder has been removed is performed by immersing the metal base material having the coating layer from which the organic binder has been removed formed on its surface into the liquid metal-based organic material, and the immersion is performed for 1 second to 10 minutes.

15. The method for manufacturing a metal separator according to claim 8, wherein the secondary heat treatment is performed in a vacuum atmosphere at 250° C. to 900° C. for 10 seconds to 24 hours.

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