Metal separation plate and method for manufacturing the same

Abstract

This application relates to a metal separation plate and a method for manufacturing the same, comprising a first base material and a porous body laminated on the upper surface of the first base material, wherein the porous body comprises a plurality of holes and a surface layer present between the plurality of holes, and a surface modification layer is formed on the upper surface of the surface layer and on the inner surface of the holes, respectively. According to the metal separation plate and method for manufacturing the same of this application, the metal separation plate is not only excellent in electrical conductivity but also excellent in corrosion resistance.

Description

[Technical Field]

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

[0002] In recent years, in response to global warming, powertrains have been shifting from internal combustion engines (ICE) to electric vehicles (EVs) and hydrogen fuel cell vehicles (FCEVs). Fuel cells used in hydrogen fuel cell vehicles (FCEVs) are used not only to supply power for industrial, household, and vehicle propulsion, but also to power small electronic products such as portable devices. As a highly efficient and clean energy source, their applications are 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 contained in a fuel into electrical energy by electrochemically reacting it within a stack. It generates electricity using the energy produced during the bonding reaction between hydrogen and oxygen. Specifically, a fuel cell can use hydrogen gas or a substance capable of generating hydrogen as fuel. The oxidation reaction of the fuel proceeds, generating hydrogen ions (protons) and electrons. At that time, the generated hydrogen ions and electrons undergo an electrochemical reaction with oxygen in the air, producing water and generating electrical energy from the flow of electrons.

[0004] Such hydrogen fuel cells consist of a membrane electrode assembly, a gas diffusion layer (GDL), and a metal separator.

[0005] In this configuration, the metal separator must separate hydrogen, oxygen, and cooling water, respectively, and uniformly distribute and supply them across the entire surface of the membrane electrode assembly in order to ensure a smooth electrochemical reaction of the membrane electrode assembly. Therefore, the required properties of the metal separator material include not only low cost, but also excellent processability, excellent mechanical strength, high electrical conductivity, low gas permeability, thermal conductivity, and chemical stability.

[0006] The shape of the metal separation plate can be broadly divided into two parts: a reaction section formed in the center, and manifold sections formed on both sides of the reaction section.

[0007] Since the reaction section of the metal separation plate is in contact with the membrane electrode assembly or gas diffusion layer, flow channels are formed to guide the flow of hydrogen, oxygen, and cooling water. To enhance the role of these flow channels, a porous material with multiple holes can be added, allowing the metal separation plate to be manufactured with a two-layer structure.

[0008] On the other hand, metal separation plates can undergo surface modification before the porous body piercing process to improve corrosion resistance and conductivity. However, this can lead to exposed areas in the porous body of the metal separation plate, resulting in the disadvantage of not being able to ensure corrosion resistance.

[0009] Therefore, in order to solve these problems, there is a need for a metal separation plate that not only has excellent electrical conductivity but also excellent corrosion resistance, as well as a method for manufacturing the same. [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of this application is to provide a metal separation plate and a method for manufacturing the same that not only has excellent electrical conductivity but also excellent corrosion resistance. [Means for solving the problem]

[0011] To solve the above problems, the metal separation plate of the present application includes a first base material; and a porous body laminated on the upper surface of the first base material. The porous body includes a plurality of holes and a surface layer portion existing between the plurality of holes. A surface modification layer is formed on the upper surface of the surface layer portion and the inner surface of the holes, respectively.

[0012] The porous body may contain 28.000% to 33.000% by weight of chromium, 0.010% by weight or less of carbon, 0.200% by weight or less of silicon, 0.300% by weight or less of manganese, 0.300% by weight or less of titanium, and the remaining iron and other inevitable impurities.

[0013] In addition, the surface modification layer formed on the upper surface of the surface layer portion may contain chromium at 20 at% to 28 at% in a region from the surface exposed to the outside to a depth of 1.0 nm.

[0014] Furthermore, the surface modification layer formed on the upper surface of the surface layer portion may contain iron at 15 at% to 25 at% in a region from the surface exposed to the outside to a depth of 1.0 nm.

[0015] Also, the porous body may have a contact resistance of 14 mΩ·cm or less under a contact pressure of 1.0 MPa. 2 or less.

[0016] Furthermore, the porous body may have a current density of 13 μA / cm or less at a potential of 0.6 V. vs SCE or less. 2 or less.

[0017] In addition, the first base material may include a first manifold portion, a second manifold portion, and a reaction portion provided between the first manifold portion and the second manifold portion.

[0018] Furthermore, the fuel cell of the present application includes the metal separation plate.

[0019] In addition, the method for manufacturing the metal separation plate of the present application includes a preparation step of preparing a first base material and a second base material respectively; a porous body piercing step of punching the second base material to form a porous body having a plurality of holes and a surface layer portion existing between the plurality of holes; a surface modification layer forming step of modifying the surface exposed outside the porous body to form a surface modification layer on the exposed surface of the porous body; and a laminate forming step of laminating and joining the porous body to the central portion of the first base material to form a laminate. A surface modification layer is formed on the upper surface of the surface layer portion and the inner surface of the holes respectively.

[0020] Furthermore, the second base material may contain 28.000% to 33.000% by weight of chromium, 0.010% by weight or less of carbon, 0.200% by weight or less of silicon, 0.300% by weight or less of manganese, 0.300% by weight or less of titanium, and the remaining iron and other inevitable impurities.

[0021] In addition, the surface modification layer forming step may include a first modification step of preparing a solution in which one or more selected from fluorine, hydrochloric acid, and phosphoric acid are added to a sulfuric acid solution and depositing the surface of the porous body on the solution; and a second modification step of depositing the porous body that has undergone the first modification step on a solution containing hydrogen peroxide and fluorine.

[0022] Furthermore, the method for manufacturing the metal separation plate may further include a cold rolling step of cold rolling each of the prepared first base material and second base material.

[0023] In addition, the method for manufacturing the metal separation plate may further include a slitting step of slitting the width of each of the prepared first base material and second base material.

[0024] Furthermore, the method for manufacturing the metal separation plate may further include a manifold portion piercing step of punching both side surfaces of one surface of the prepared first base material to form each of a first manifold portion and a second manifold portion including a plurality of apertures.

Advantages of the Invention

[0025] The metal separation plate and its manufacturing method described in this application not only have excellent electrical conductivity but also excellent corrosion resistance. [Brief explanation of the drawing]

[0026] [Figure 1] Figure 1 is an illustrative top view showing a metal separation plate according to one embodiment of the present application.

[0027] [Figure 2] Figure 2 is a side view illustrating an exemplary metal separation plate according to one embodiment of this application. [Modes for carrying out the invention]

[0028] The metal separator of this application will be described below with reference to the attached drawings. The attached drawings are illustrative and the metal separator of this application is not limited by them.

[0029] Figure 1 is an illustrative top view showing a metal separation plate according to one embodiment of the present application. As shown in Figure 1, the metal separation plate of the present application includes a first base material 110 and a porous body 120. The metal separation plate of the present application has excellent electrical conductivity as well as excellent corrosion resistance.

[0030] The first base material 110 is a material used for a metal separation plate for a fuel cell and may include a first manifold section 111, a second manifold section 112, and a reaction section 113 provided between the first manifold section 111 and the second manifold section 112.

[0031] The first manifold section 111 and the second manifold section 112 are parts that supply hydrogen and air to the first base material 110, respectively, so that an electrochemical reaction occurs in the separation plate, and each may be provided with a plurality of openings and a surface layer located between the plurality of openings. Specifically, the first manifold section 111 and the second manifold section 112 each have hydrogen and air inlet and outlet ports for supplying and discharging hydrogen and air, and cooling water inlet and outlet ports for adjusting the operating temperature, and the respective surface layers may exist between the respective inlet and outlet ports. In one embodiment, the first manifold section 111 is formed at one end of the first base material 110 in the longitudinal direction, and a hydrogen inlet, a cooling water outlet, and an air outlet are formed along the width direction perpendicular to the longitudinal direction of the first base material 110, and the respective surface layers may exist between the hydrogen inlet, a cooling water outlet, and an air outlet. Furthermore, the second manifold portion 112 is formed at the other end of the first base material 110 with respect to its longitudinal direction, and an air inlet, a cooling water inlet, and a hydrogen outlet are formed along the width direction perpendicular to the longitudinal direction of the first base material 110, with surface portions of each of the air inlet, cooling water inlet, and hydrogen outlet being present between them. In this case, the number of openings is not particularly limited as long as there are two or more, so there is no particular upper limit. In this specification, "manifold portion" is used to refer to both the first manifold portion and the second manifold portion. Furthermore, the longitudinal direction is the direction from one end to the other in the first base material 110. Furthermore, the width direction is the direction perpendicular to the longitudinal direction.

[0032] In one example, the first manifold section 111 and the second manifold section 112 have a surface modification layer or a passivation film formed on the upper surface of the surface layer and / or the inner surface of the openings, respectively. When a surface modification layer is formed on the upper surface of the surface layer and / or the inner surface of the openings provided in each of the first manifold section 111 and the second manifold section 112, excellent corrosion resistance and electrical conductivity of the manifold section can be ensured. Furthermore, when a passivation film is formed on the upper surface of the surface layer and / or the inner surface of the openings provided in each of the first manifold section 111 and the second manifold section 112, oxygen can be blocked from entering the interior of the first base material 110, thereby preventing rust from occurring.

[0033] Furthermore, the first base material 110 may contain chromium in an amount of 28,000% to 33,000% by weight, carbon in an amount of 0.010% by weight or less, silicon in an amount of 0.200% by weight or less, manganese in an amount of 0.300% by weight or less, titanium in an amount of 0.300% by weight or less, the remaining iron and other unavoidable impurities. In one embodiment, the first base material 110 may contain chromium in an amount of 28,000% to 33,000% by weight, carbon in an amount of 0.010% by weight or less, silicon in an amount of 0.200% by weight or less, manganese in an amount of 0.300% by weight or less, titanium in an amount of 0.300% by weight or less, the remaining iron and other unavoidable impurities. Specifically, the first base material 110 may have an upper limit of chromium content of approximately 32.000% by weight or less, or approximately 31.000% by weight or less, and a lower limit of chromium content of approximately 29.000% by weight or more. Furthermore, the first base material 110 may have a lower limit of carbon content of approximately 0.001% by weight or more, a lower limit of silicon content of approximately 0.100% by weight or more, a lower limit of manganese content of approximately 0.100% by weight or more, and a lower limit of titanium content of approximately 0.100% by weight or more. Since the first base material 110 is made of stainless steel containing chromium with the above-mentioned content, when the surface is exposed to the outside, a very thin Cr2O3 passivation film with a thickness of 1 nm to 5 nm, in one embodiment, approximately 1 nm to approximately 5 nm, is naturally formed on the surface, and when the passivation film is modified, a surface modification layer is formed. At this time, the physical properties of each component contained in the first base material 110 are known in the industry, so they will be omitted.

[0034] In one example, the first base material 110 may further contain one or more selected from phosphorus at a rate of 0.030% by weight or less, sulfur at a rate of 0.002% by weight or less, and niobium at a rate of 0.300% by weight or less. In one embodiment, the first base material 110 may further contain one or more selected from phosphorus at a rate of about 0.030% by weight or less, sulfur at a rate of about 0.002% by weight or less, and niobium at a rate of about 0.300% by weight or less. The lower limits of the phosphorus, sulfur, and niobium are not particularly limited, and for example, each may be at a rate of about 0% by weight or more.

[0035] In a further example, the thickness of the first base material 110 may be 0.05 mm to 1 mm, or in one embodiment, approximately 0.05 mm to approximately 1 mm. The first base material 110 has excellent mechanical strength and gas permeability due to having a thickness within the aforementioned range.

[0036] The reaction section 113 is a part in which an electrochemical reaction occurs due to hydrogen and air supplied and discharged via the first manifold section 111 and the second manifold section 112, respectively, and the porous body 120 is laminated on its upper surface. The shape of the reaction section 113 is not particularly limited, and as an example, it may be flat. By laminating the porous body 120 on the flat reaction section 113, it may be unnecessary to form a separate flow channel. A separation plate having the shape of such a reaction section 113 can be applied to and used for both the hydrogen electrode and the air electrode.

[0037] The porous body 120 is a channel having a porous microporous structure where the aforementioned electrochemical reaction occurs, and is laminated on the upper surface of the first base material 110, specifically on the upper surface of the reaction section 113. At this time, the porous body 120 has an area corresponding to the reaction section 113 of the first base material 110. In this specification, "corresponding area" means the same area. By laminating the porous body 120 on the upper surface of the reaction section 113 of the first base material 110, the role of the hydrogen or air channel can be improved.

[0038] Furthermore, the porous body 120 contains chromium in an amount of 28,000% to 33,000% by weight, carbon in an amount of 0.010% by weight or less, silicon in an amount of 0.200% by weight or less, manganese in an amount of 0.300% by weight or less, titanium in an amount of 0.300% by weight or less, the remaining iron and other unavoidable impurities. In one embodiment, the porous body 120 may contain chromium in an amount of 28,000% to 33,000% by weight, carbon in an amount of 0.010% by weight or less, silicon in an amount of 0.200% by weight or less, manganese in an amount of 0.300% by weight or less, titanium in an amount of 0.300% by weight or less, the remaining iron and other unavoidable impurities. Specifically, the porous body 120 may have an upper limit of chromium content of approximately 32,000% by weight or less, or approximately 31,000% by weight or less, and a lower limit of chromium content of approximately 29,000% by weight or more. Furthermore, the porous body 120 may have a lower limit of carbon content of approximately 0.001% by weight or more, a lower limit of silicon content of approximately 0.100% by weight or more, a lower limit of manganese content of approximately 0.100% by weight or more, and a lower limit of titanium content of approximately 0.100% by weight or more. By containing the above-mentioned components, the porous body 120 not only has excellent electrical conductivity but also excellent corrosion resistance. At this time, the physical properties of each component contained in the first base material 110 are known in the industry and are therefore omitted.

[0039] In one example, the porous body 120 may further contain one or more selected from phosphorus at a rate of 0.030% by weight or less, sulfur at a rate of 0.002% by weight or less, and niobium at a rate of 0.300% by weight or less. In one embodiment, the porous body 120 may further contain one or more selected from phosphorus at a rate of about 0.030% by weight or less, sulfur at a rate of about 0.002% by weight or less, and niobium at a rate of about 0.300% by weight or less. The lower limit of the phosphorus, sulfur, and niobium may be, for example, about 0% by weight or more, without any particular limitation.

[0040] Figure 2 is a side view illustrating an example of a metal separation plate according to one embodiment of the present application. As shown in Figure 2, the porous body 120 comprises a plurality of holes 121 and surface layers 122 located between each of the plurality of holes 121, and surface modification layers 123 and 124 are formed on the upper surface of each surface layer 122 and on the inner surface of each hole 121 provided on the porous body 120. In this case, the number of holes provided on the porous body 120 is not particularly limited as long as there are two or more, so there is no particular upper limit. The porous body 120 has excellent electrical conductivity as well as excellent corrosion resistance because the aforementioned surface modification layers 123 and 124 are formed on the upper surface of the surface layer 122 and on the inner surface of each hole 121.

[0041] In one example, the surface modification layer 123 formed on the upper surface of the surface layer 122 provided on the porous body 120 may contain chromium at a concentration of 20 at% to 28 at% in the region from the surface exposed to the outside to a depth of 1.0 nm, and in one embodiment, it may contain approximately 20 at% to approximately 28 at%, specifically approximately 22 at% to approximately 27 at%, or approximately 24 at% to approximately 26 at%. By containing chromium at the aforementioned concentration in the region from the surface exposed to the outside to a depth of 1.0 nm, the surface modification layer 123 formed on the upper surface of the surface layer 122 provided on the porous body 120 not only exhibits excellent electrical conductivity but also excellent corrosion resistance. At this time, the chromium content of the surface modification layer 123 formed on the upper surface of the surface layer 122 provided on the porous body 120 can be measured using EDAX equipment.

[0042] For example, the surface modification layer 123 formed on the upper surface of the surface layer 122 provided on the porous body 120 may contain 15 at% to 25 at% iron in the region from the surface exposed to the outside to a depth of 1.0 nm, and in one embodiment, it may contain about 15 at% to about 25 at%, specifically about 17 at% to about 23 at%, or about 19 at% to about 21 at%. By containing iron in the aforementioned amounts in the region from the surface exposed to the outside to a depth of 1.0 nm, the surface modification layer 123 formed on the upper surface of the surface layer 122 provided on the porous body 120 not only has excellent electrical conductivity but also excellent corrosion resistance. At this time, the iron content of the surface modification layer 123 formed on the upper surface of the surface layer 122 provided on the porous body 120 can be measured using EDAX equipment.

[0043] The plurality of holes 121 may have a short axis length formed in a direction parallel to the airflow direction and a long axis length formed in a direction perpendicular to the airflow direction. For example, the short axis length may be 0.3 mm to 1.0 mm, and in one embodiment, approximately 0.3 mm to 1.0 mm. The long axis length may be 1.0 mm to 2.0 mm, and in one embodiment, approximately 1.0 mm to 2.0 mm. By having the lengths described above, the function of the plurality of holes 121 as hydrogen or air passages can be improved.

[0044] The upper surface of the surface layer portion 122 provided in the porous body 120 and the surface modification layers 123 and 124 formed on the inner surfaces of the holes 121 may each have a thickness of 5 nm or less. In one embodiment, the upper surface of the surface layer portion 122 provided in the porous body 120 and the surface modification layers 123 and 124 formed on the inner surfaces of the holes 121 may each have a thickness of about 5 nm or less. Specifically, the thicknesses of the surface modification layers 123 and 124 formed on the upper surface of the surface layer portion 122 provided in the porous body 120 and the inner surfaces of the holes 121 may be about 4 nm or less, or about 3 nm or less. Also, the lower limit of the thickness of the surface modification layer 123 provided in the porous body 120 may be about 1 nm or more. When the upper surface of the surface layer portion 122 provided in the porous body 120 and the surface modification layers 123 and 124 formed on the inner surfaces of the holes 121 have the aforementioned thicknesses, not only is the porous body excellent in electrical conductivity, but it is also excellent in corrosion resistance.

[0045] In one example, the porous body 120 has a contact resistance of 14 mΩ·cm under a contact pressure of 1.0 MPa 2 or less. In one embodiment, the porous body 120 has a contact resistance of about 14 mΩ·cm under a contact pressure of 1.0 MPa 2 or less. Since the contact resistance of the porous body 120 measured under the aforementioned contact pressure has the aforementioned range, it is excellent in electrical conductivity. Also, from the aspect that the lower the contact resistance of the porous body 120 measured under the aforementioned contact pressure, the more excellent the electrical conductivity, the lower limit is not particularly limited, but for example, it may be about 1 mΩ·cm 2 or more, specifically, about 3 mΩ·cm 2 or more, about 5 mΩ·cm 2 or more, about 10 mΩ·cm 2 or more, or about 12 mΩ·cm 2 or more.

[0046] In a further example, the porous body 120 has a current density of 13 μA / cm² at a potential of 0.6 V vs SCE or less. In one embodiment, the porous body 120 has a potential of 0.6 V 2 <0000-014>vs SCE At this potential, the current density is approximately 13 μA / cm². 2 The following is possible. The porous body 120 has excellent corrosion resistance because the current density measured at the aforementioned potential is within the aforementioned range. Furthermore, the lower the current density of the porous body 120 measured at the aforementioned potential, the better the corrosion resistance, so there is no particular lower limit, but for example, about 1 μA / cm 2 The above is a possible scenario, specifically about 3 μA / cm². 2 More than about 5μA / cm 2 More than about 10μA / cm 2 Above or approximately 12 μA / cm² 2 It could be any of the above.

[0047] This application also relates to a fuel cell. The fuel cell includes the aforementioned metal separator plate, and the specific details regarding the metal separator plate described below are omitted because the same information as described for the metal separator plate applies to it.

[0048] The fuel cell includes the aforementioned metal separation plate. By including the aforementioned metal separation plate, the fuel cell can enable smooth electrochemical reactions in the membrane electrode assembly and smoothly function as an electrical pathway.

[0049] The fuel cell includes two of the aforementioned metal separation plates, and between the two metal separation plates are a first gas diffusion layer, a membrane electrode assembly, and a second gas diffusion layer. In this case, the first gas diffusion layer, the membrane electrode assembly, and the second gas diffusion layer can be of any type known in the industry without limitation, and are not particularly limited.

[0050] This application also relates to a method for manufacturing a metal separation plate. The method for manufacturing the metal separation plate is the same as the method for manufacturing the metal separation plate described above, and the specific details regarding the metal separation plate described below are omitted here, as the same content described in the section on the metal separation plate applies to it.

[0051] The present invention relates to a method for manufacturing a metal separation plate, which includes a preparation step, a porous body piercing step, a surface modification layer formation step, and a laminate formation step. According to the present invention relates to a method for manufacturing a metal separation plate, it is possible to manufacture a metal separation plate that is not only excellent in electrical conductivity but also in corrosion resistance.

[0052] The aforementioned preparation step is the step of preparing the first base material and the second base material, respectively.

[0053] For example, the second base material contains chromium in an amount of 28,000% to 33,000% by weight, carbon in an amount of 0.010% by weight or less, silicon in an amount of 0.200% by weight or less, manganese in an amount of 0.300% by weight or less, titanium in an amount of 0.300% by weight or less, the remaining iron and other unavoidable impurities. In one embodiment, the second base material may contain chromium in an amount of approximately 28,000% to 33,000% by weight, carbon in an amount of approximately 0.010% by weight or less, silicon in an amount of approximately 0.200% by weight or less, manganese in an amount of approximately 0.300% by weight or less, titanium in an amount of approximately 0.300% by weight or less, the remaining iron and other unavoidable impurities. Specifically, the upper limit of the chromium content in the second base material may be approximately 32,000% by weight or less, or approximately 31,000% by weight or less, and the lower limit of the chromium content may be approximately 29,000% by weight or more. Furthermore, the second base material may have a lower limit of carbon content of approximately 0.001% by weight or more, a lower limit of silicon content of approximately 0.100% by weight or more, a lower limit of manganese content of approximately 0.100% by weight or more, and a lower limit of titanium content of approximately 0.100% by weight or more. By containing the above-mentioned components, the second base material naturally forms a very thin Cr2O3 passivation film on its surface, with a thickness of 1 nm to 5 nm, or approximately 1 nm to 5 nm in one embodiment.

[0054] Furthermore, the second base material may further contain one or more selected from phosphorus at a rate of 0.030% by weight or less, sulfur at a rate of 0.002% by weight or less, and niobium at a rate of 0.300% by weight or less. In one embodiment, the second base material may further contain one or more selected from phosphorus at a rate of about 0.030% by weight or less, sulfur at a rate of about 0.002% by weight or less, and niobium at a rate of about 0.300% by weight or less. The lower limits of the phosphorus, sulfur, and niobium are not particularly limited, and for example, each may be at a rate of about 0% by weight or more.

[0055] In one example, the first base material may contain the same components as the second base material. By containing the same components as the second base material, the first base material naturally forms a very thin Cr2O3 passivation film on its surface, with a thickness of 1 nm to 5 nm, or approximately 1 nm to 5 nm in one example.

[0056] In one example, the method for manufacturing the metal separation plate may further include a cold rolling step. Specifically, the cold rolling step is a step of forming the first base material and the second base material by passing them between two rolls rotating at or below the recrystallization temperature, and is performed in the preparation step. By further including the cold rolling step, the method for manufacturing the metal separation plate can improve the dimensional accuracy and mechanical properties of the first base material and the second base material. In this case, when the first base material and / or the second base material are exposed to the outside during each step of the method for manufacturing the metal separation plate, a passivation film is formed on the surface of each of the first base material and / or the second base material by natural oxidation. Specifically, when the base material is made of stainless steel containing 12 wt% or more of chromium, or about 12 wt% or more in one embodiment, a very thin Cr2O3 passivation film with a thickness of 1 nm to 5 nm, or about 1 nm to about 5 nm in one embodiment, is naturally formed on the surface of the base material. As a result, since each of the first and second base materials is made of stainless steel containing chromium having the aforementioned content, a very thin Cr2O3 passivation film with a thickness of 1 nm to 5 nm, or approximately 1 nm to 5 nm in one embodiment, is naturally formed.

[0057] In one example, the method for manufacturing the metal separation plate may further include a slitting step. Specifically, the slitting step is a step of slitting the first base material and the second base material prepared in the preparation step to a width suitable for application to the metal separation plate. For example, the width of the prepared first base material and the second base material is divided into quarters via the slitting step.

[0058] The porous body piercing step is a step of forming the second base material into a porous body having a plurality of holes and a surface layer present between the plurality of holes, and is performed by punching out the second base material.

[0059] In one example, the method for manufacturing the metal separation plate may further include a three-dimensional molding step. The three-dimensional molding step is a step for forming air passages in the porous body, which is performed by forming the porous body with a press. By further including the three-dimensional molding step, the method for manufacturing the metal separation plate can ensure three-dimensional air passages in the porous body via the three-dimensional molding step.

[0060] In one example, the method for manufacturing the metal separation plate may further include a manifold piercing step. The manifold piercing step is a step of forming a first manifold portion and a second manifold portion, respectively, on the first base material prepared in the preparation step, by punching out both sides of one surface of the first base material prepared in the preparation step. Specifically, the manifold piercing step is performed after the slitting step or the porous body piercing step.

[0061] The surface modification layer formation step is a step of forming a surface modification layer on the exposed surface of the porous body via the porous body piercing step, and is carried out by modifying the surface exposed to the outside of the porous body, specifically the passivation film formed on the surface of the porous body, so that the surface modification layer is formed on the upper surface of the surface layer and the inner surface of the holes.

[0062] Even if the second base material contains the aforementioned components, the method for manufacturing the metal separation plate allows for the production of a metal separation plate that is not only electrically conductive but also corrosion resistant, by performing the surface modification layer formation step after the porous body piercing step.

[0063] In one example, the surface modification layer formation step may include a first modification step and a second modification step.

[0064] The first modification step is a step in which a passive film formed on the surface of the porous body is removed and the chemical components are reconstituted, and is carried out by preparing a solution in which one or more substances selected from fluorine, hydrochloric acid, and phosphoric acid are added to a sulfuric acid solution, and depositing the surface of the porous body into the solution. Specifically, the first modification step is carried out by preparing a solution in which one or more substances selected from 1.0 mol to 5.0 mol of fluorine, 0.3 mol to 1.0 mol of hydrochloric acid, and 0.3 mol to 1.0 mol of phosphoric acid are added to a sulfuric acid solution having a concentration of 350 g / L or more, and depositing the surface of the porous body, specifically the passive film formed on the surface of the porous body, into the solution at 40°C to 80°C for 10 to 180 seconds. In one embodiment, the first modification step involves preparing a solution in which one or more substances selected from approximately 1.0 mol to approximately 5.0 mol of fluorine, approximately 0.3 mol to approximately 1.0 mol of hydrochloric acid, and approximately 0.3 mol to approximately 1.0 mol of phosphoric acid are added to a sulfuric acid solution having a concentration of approximately 350 g / L or more, and then depositing the surface of the porous material, specifically the passivation film formed on the surface of the porous material, into the solution at approximately 40°C to approximately 80°C for approximately 10 seconds to approximately 180 seconds. By including the first modification step, the method for manufacturing the metal separation plate improves the amount of chromium hydroxide generated in the surface modification layer, thereby enabling the production of a metal separation plate with improved corrosion resistance and electrical conductivity. At this time, the component ratio contained in the surface modification layer can be adjusted by the component ratio of the solution used in the first modification step and the deposition conditions.

[0065] The second modification step is a step to remove smut, a by-product that may be generated via the first modification step, and is performed immediately after the first modification step, by depositing the porous material via the first modification step into a solution containing hydrogen peroxide and fluorine. Specifically, the second modification step is performed by depositing the porous material via the first modification step into a solution containing 1.0 mol to 5.0 mol of hydrogen peroxide and 1.0 mol to 5.0 mol of fluorine at 40°C to 80°C for 10 to 180 seconds. In one embodiment, the second modification step is performed by depositing the porous material via the first modification step into a solution containing about 1.0 mol to about 5.0 mol of hydrogen peroxide and about 1.0 mol to about 5.0 mol of fluorine at about 40°C to about 80°C for about 10 to 180 seconds. By including the second modification step, the surface modification layer formation step can ensure the cleanliness of the surface of the surface modification layer.

[0066] In one example, the surface modification layer formation step may further include modifying the exposed surface of the first base material and forming a surface modification layer on the first base material. Specifically, the surface modification layer formation step on the first base material is performed on the first base material prepared in the preparation step before the manifold piercing step, or on the first base material via the manifold piercing step. The method for forming the surface modification layer on the exposed surface of the first base material is similar to the method for forming the surface modification layer on the exposed surface of the porous body, so it is omitted here. If the surface modification layer formation step on the first base material is performed before the manifold piercing step, after the manifold piercing step, the surface modification layer is formed on the upper surface of the surface layer provided in the first manifold and the second manifold, respectively, and a passivation film is formed on the inner surface of the opening. Furthermore, if the surface modification layer formation step for the first base material is performed after the manifold piercing step, the surface modification layer is formed on the upper surface of the surface layer and the inner surface of the openings provided in the first and second manifold sections, respectively.

[0067] The laminate formation step is a step of forming a laminate consisting of the first base material and a porous body having the upper surface of the surface layer and the inner surface of the holes, wherein the porous body is laminated and joined to the center of the first base material. For example, as the joining method, a joining method using laser welding or micro-spot welding can be used. By including the laminate formation step, the method for manufacturing the metal separation plate can be used to manufacture a two-layer metal separation plate in which the porous body having the upper surface of the surface layer and the inner surface of the holes is laminated on the first base material.

[0068] The present application will be described in more detail below through examples provided in this application and comparative examples not provided in this application, but the scope of this application is not limited to the examples presented below.

[0069] Example 1 Manufacturing of metal separators A first base material with a thickness of 0.1 mm and a second base material with a thickness of 0.08 mm were prepared, each consisting of 30,000 wt% chromium, 0.006 wt% carbon, 0.144 wt% silicon, 0.200 wt% manganese, 0.016 wt% phosphorus, 0.001 wt% sulfur, 0.200 wt% titanium, 0.200 wt% niobium, and the remaining iron and other unavoidable impurities. Cold rolling was performed by passing the first and second base materials between two rotating rolls. During this process, a very thin Cr2O3 passivation film of 1 nm to 5 nm thickness was naturally formed on the surfaces of the first and second base materials through spontaneous oxidation.

[0070] Next, the width of each of the first and second base materials was slit down to 1 / 4 at 500 mm intervals, dividing them into sections with a width of 120 mm.

[0071] Next, after piercing the second base material, it was three-dimensionally molded using a press to form a porous body having multiple holes and surface layers between the multiple holes. During this three-dimensional molding process, the unnecessary outer casing of the porous body was removed.

[0072] Next, the first base material was punched out on both sides of one surface, forming a first manifold section and a second manifold section, respectively, which include a plurality of openings and a surface layer located between the plurality of openings.

[0073] Next, a solution was prepared by adding 3.0 mol of fluorine to a sulfuric acid solution having a concentration of 400 g / L. A first modification treatment was performed by depositing the surface of the first base material and the porous body in this solution at a temperature of 60°C for 30 seconds. Then, a second modification treatment was performed by depositing the surface of the first base material and the porous body in a solution containing 3.5 mol of hydrogen peroxide and 2.5 mol of fluorine at a temperature of 60°C for 60 seconds. By forming a surface modification layer on the surface of the first base material and the porous body, a surface modification layer with a thickness of 2 nm was formed on the upper surface of the surface layer and on the inner surface of the openings or holes, respectively.

[0074] Next, the porous material was laminated onto the center of the first base material and laser bonding was performed to manufacture a metal separation plate with the porous material laminated on the first base material.

[0075] Comparative Example 1 Manufacturing of metal separators A first base material with a thickness of 0.1 mm and a second base material with a thickness of 0.08 mm were prepared, each consisting of 30,000 wt% chromium, 0.006 wt% carbon, 0.144 wt% silicon, 0.200 wt% manganese, 0.016 wt% phosphorus, 0.001 wt% sulfur, 0.200 wt% titanium, 0.200 wt% niobium, and the remaining iron and other unavoidable impurities. Cold rolling was performed by passing the first and second base materials between two rotating rolls. During this process, a very thin Cr2O3 passivation film with a thickness of 1 nm to 5 nm was naturally formed on the surface of each of the first and second base materials by spontaneous oxidation.

[0076] Next, a solution was prepared by adding 3.0 mol of fluorine to a sulfuric acid solution having a concentration of 400 g / L. A first modification treatment was performed by depositing the surface of each of the first and second base materials into this solution at a temperature of 60°C for 30 seconds. Subsequently, a second modification treatment was performed by depositing the surface of each of the first and second base materials into a solution containing 3.5 mol of hydrogen peroxide and 2.5 mol of fluorine at a temperature of 60°C for 60 seconds, thereby forming a surface modification layer with a thickness of 2 nm on each of the surfaces of the first and second base materials.

[0077] Next, the width of each of the first and second base materials on which the surface modification layer is formed was slit to 1 / 4 of its original width at 500 mm, dividing them into sections with a width of 120 mm.

[0078] Next, after piercing the second base material on which the surface modification layer is formed, the material was three-dimensionally molded by pressing to form a porous body having multiple holes and a surface layer between the multiple holes, with the surface modification layer formed on the upper surface of the surface layer, and no surface modification layer formed on the inner surface of the holes, where a 1 nm thick passivation film is formed. At this time, unnecessary outer portions of the porous body were removed during the three-dimensional molding process.

[0079] Next, in the first base material on which the surface modification layer is formed, both sides of one surface of the first base material were punched out to form a first manifold section and a second manifold section, respectively, which include a plurality of openings and a surface layer located between the plurality of openings.

[0080] Next, the porous material was laminated onto the center of the first base material, and laser bonding was performed to manufacture a metal separation plate in which the porous material was laminated on the first base material.

[0081] Comparative Example 2 Manufacturing of metal separators A metal separation plate was manufactured in the same manner as in Example 1, except that the first and second modification treatments were omitted. In this case, a very thin Cr2O3 passivation film with a thickness of 1 nm to 5 nm was naturally formed on the upper surface of the porous surface layer and on the inner surface of the holes of the manufactured metal separation plate.

[0082] Experimental Example 1. Component Analysis and Evaluation of Surface Modified Layer and Passivation Film Using energy-dispersive spectroscopy (EDS) with EDAX equipment, the components of the porous metal separation plates manufactured in the above examples and comparative examples were analyzed in the region from the surface modification layer formed on the upper surface of the surface layer, or the surface exposed to the outside of the passivation film, down to a depth of 1.0 nm. The results are shown in Table 1 below.

[0083] Experimental Example 2: Evaluation of Contact Resistance The contact resistance of the porous metal separation plates produced in the examples and comparative examples was measured by inserting the metal separation plates produced in the examples and comparative examples between gas diffusion layers (carbon paper type, SGL Co., Ltd.) and then measuring the current under a contact pressure of 1.0 MPa. The results are shown in Table 1 below.

[0084] Experimental Example 3. Current Density Evaluation The current density for the porous metal separation plates produced in the examples and comparative examples was evaluated using the Tafel slope of a potentiostat, with a potential-dynamic evaluation performed using a mixture of 0.1N sulfuric acid heated to 80°C and 2 ppm hydrofluoric acid, yielding a value of 0.6V. vs SCE The measurement is taken when the voltage is applied, and the results are shown in Table 1 below.

[0085] [Table 1]

[0086] As shown in Table 1 above, the metal separation plate manufactured in Example 1 has the desired porous current density and has lower porous contact resistance compared to the metal separation plates manufactured in Comparative Examples 1 and 2, thus demonstrating superior electrical conductivity and corrosion resistance. [Explanation of Symbols]

[0087] 110: 1st base material 111: First Manifold Section 112: Second Manifold Section 113: Reaction section 120: Porous material 121: Hall 122: Surface layer 123: Surface modification layer formed on the upper surface of the surface layer 124: Surface modification layer formed on the inner surface of the hole

Claims

1. A first base material; and a porous body laminated on the upper surface of the first base material, The porous body comprises a plurality of holes and a surface layer present between the plurality of holes. A metal separation plate having a surface modification layer formed on the upper surface of the surface layer and on the inner surface of the hole, respectively.

2. The metal separation plate according to claim 1, wherein the porous body contains 28,000% to 33,000% by weight of chromium, 0.010% by weight or less of carbon, 0.200% by weight or less of silicon, 0.300% by weight or less of manganese, 0.300% by weight or less of titanium, the remainder being iron and other unavoidable impurities.

3. The metal separation plate according to claim 1, wherein the surface modification layer formed on the upper surface of the surface portion contains chromium in an amount of 20 at% to 28 at% in a region from the surface exposed to the outside to a depth of 1.0 nm.

4. The metal separation plate according to claim 1, wherein the surface modification layer formed on the upper surface of the surface portion contains iron in an amount of 15 at% to 25 at% in a region from the surface exposed to the outside to a depth of 1.0 nm.

5. The porous material has a contact resistance of 14 mΩ·cm under a contact pressure of 1.0 MPa. ２ The metal separation plate according to claim 1, which is as follows:

6. The porous material is 0.6V ｖｓ ＳＣＥ At a potential of 13 μA / cm², the current density is 13 μA / cm². ２ The metal separation plate according to claim 1, which is as follows:

7. The metal separation plate according to claim 1, wherein the first base material includes a first manifold section, a second manifold section, and a reaction section provided between the first manifold section and the second manifold section.

8. A fuel cell cell comprising a metal separation plate according to any one of claims 1 to 7.

9. Preparation step: Prepare the first base material and the second base material, respectively; A porous body piercing step involves punching out the second base material to form a porous body having a plurality of holes and a surface layer between the plurality of holes; A surface modification layer formation step of modifying the surface exposed to the outside of the porous body and forming a surface modification layer on the exposed surface of the porous body; and, The step includes forming a laminate by stacking and joining the porous material on the central part of the first base material, A method for manufacturing a metal separation plate, wherein a surface modification layer is formed on the upper surface of the surface layer and on the inner surface of the hole, respectively.

10. The method for manufacturing a metal separation plate according to claim 9, wherein the second base material comprises 28,000% to 33,000% by weight of chromium, 0.010% by weight or less of carbon, 0.200% by weight or less of silicon, 0.300% by weight or less of manganese, 0.300% by weight or less of titanium, the remaining iron and other unavoidable impurities.

11. The surface modification layer formation step includes a first modification step of preparing a solution in which one or more substances selected from fluorine, hydrochloric acid, and phosphoric acid are added to a sulfuric acid solution, and depositing the surface of the porous body into the solution; and, A method for producing a metal separation plate according to claim 9, comprising a second modification step of depositing the porous body that has undergone the first modification step into a solution containing hydrogen peroxide and fluorine.

12. The method for manufacturing a metal separation plate according to claim 9, further comprising a cold rolling step of cold rolling each of the first and second base materials prepared above.

13. The method for manufacturing a metal separation plate according to claim 9, further comprising a slitting step of slitting the width of each of the prepared first base material and second base material.

14. The method for manufacturing a metal separation plate according to claim 9, further comprising a manifold piercing step of punching out both sides of one surface of the first base material prepared above to form a first manifold portion and a second manifold portion, each containing a plurality of openings.

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