Method for manufacturing metal separator plate and metal separator plate manufactured thereby

Abstract

The present application relates to a method for manufacturing a metal separator plate and a metal separator plate manufactured thereby. The metal separator plate manufactured by the method for manufacturing a metal separator plate of the present application may exhibit both excellent corrosion resistance and excellent electrical conductivity.

Description

Method for manufacturing a metal separator plate and a metal separator plate manufactured according to the same

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

[0002] Fuel cells used in hydrogen fuel cell vehicles (FCEVs) serve as a power source that generates electricity through the electrochemical reaction of reaction gases and catalysts. Among the components used in fuel cells, metal separators are key parts that play the role of collecting and transmitting the electricity generated by the electrochemical reaction.

[0003] Although materials with excellent electrical conductivity, such as stainless steel and polymer composites, are used as metal separators, prolonged exposure to the high-temperature and high-humidity operating environment of fuel cells accelerates metal corrosion. Furthermore, metal oxides formed on the surface act as electrical insulators, reducing electrical conductivity and causing catalyst contamination, thereby decreasing the performance of the fuel cell.

[0004] To solve this problem, Patent Document 1 (Korean Registered Patent No. 10-1165542) used a stainless steel material containing 16 wt% chromium (Cr) as a metal separator. However, when a stainless steel material containing 16 wt% chromium (Cr) is used as a metal separator, the amount of iron (Fe) ions leached from the stainless steel material becomes relatively high, and as a result, many deterioration phenomena occur during the stack lifespan, which reduces the lifespan of the fuel cell.

[0005] To address this, it is necessary to use stainless steel materials with a high chromium (Cr) content as metal separators to be advantageous in high-temperature and acidic environments. However, when a high-conductivity coating is applied to stainless steel materials with a high chromium content, the coating efficiency decreases and adhesion weakens due to the chromium oxide film.

[0006] Therefore, to solve these problems, there is a need for a method to manufacture a metal separator plate with excellent electrical conductivity and corrosion resistance by applying a process suitable for stainless steel materials with high chromium content, and for the metal separator plate manufactured thereby.

[0007] The objective of the present application is to provide a method for manufacturing a metal separator plate that has excellent electrical conductivity and excellent corrosion resistance by improving coating adhesion, and a metal separator plate manufactured according to this method.

[0008] To solve the above problem, the method for manufacturing a metal separator plate of the present application comprises, in weight percent, a pickling step of pickling the surface of a base material comprising C: greater than 0% and less than or equal to 0.1%, Si: greater than 0% and less than or equal to 0.2%, Mn: greater than 0% and less than or equal to 0.2%, P: greater than 0% and less than or equal to 0.035%, S: greater than 0% and less than or equal to 0.015%, Cr: greater than 28% and less than or equal to 34%, Ti: greater than 0% and less than or equal to 0.45%, and Cu: greater than 0% and less than or equal to 0.45%, and the remainder being Fe and other unavoidable impurities; a conductive coating step of coating a conductive material on the pickled base material; and a heat treatment step of heat treating the base material coated with the conductive material.

[0009] The above pickling step may be performed by immersing the base material in a solution containing one or more selected from sulfuric acid, hydrofluoric acid, ammonium fluoride, phosphoric acid, iron sulfate, citric acid hydrate, oxalic acid dihydrate, resin acid, and rosin acid.

[0010] Additionally, the conductive material may comprise one or more precious metal materials selected from gold (Au), platinum (Pt), ruthenium (Ru), iridium (Ir), ruthenium oxide (RuO2), and iridium oxide (IrO2); and one or more selected from carbon.

[0011] In addition, the conductive material coated on the substrate through the conductive coating step has a coating density of 5 μg / cm² 2 100 µg / cm² or higher 2 It may be less than.

[0012] In addition, the heat treatment step may be performed under vacuum or an atmospheric conditions at a temperature of more than 200°C and less than or equal to 500°C for 10 minutes or more and 120 minutes or less.

[0013] In addition, the metal separator plate manufactured through the above heat treatment step may include a base material, a conductive material discontinuously formed on the base material, and a passivation film formed between the conductive materials on the base material.

[0014] In addition, the above passivation film may have a thickness of 1 nm or more and 10 nm or less.

[0015] In addition, the conductive material may have a particle size that is larger than the thickness of the passivation film and may be 5 nm or more and 30 nm or less.

[0016] In addition, the metal separator of the present application is manufactured according to the method of manufacturing the metal separator.

[0017] In addition, the metal separator has a current density of 0.5 μA / cm² 2 It may be less than.

[0018] In addition, the metal separator has a contact resistance of 10 mΩ·cm 2 It may be less than.

[0019] According to the method for manufacturing a metal separator plate of the present application and the metal separator plate manufactured according to the same, electrical conductivity and corrosion resistance can be excellent simultaneously.

[0020] FIG. 1 is a diagram illustrating, in order to explain the pickling step according to one embodiment of the present application, a base material having impurities and / or an oxide film removed from its surface after pickling.

[0021] FIG. 2 is a diagram illustrating an exemplary metal separator plate coated with a conductive material on a pickled substrate to explain a conductive coating step according to one embodiment of the present application.

[0022] FIG. 3 is a diagram illustrating an exemplary metal separator plate having a passivation film formed on the surface of a substrate coated with a conductive material to explain a heat treatment step according to one embodiment of the present application.

[0023] FIG. 4 is a diagram exemplarily showing the structure and measurement location of a specimen for measuring the contact resistance of a metal separator plate manufactured in each of the examples and comparative examples.

[0024] FIG. 5 is a diagram exemplarily showing the structure and measurement location of a dummy specimen for comparison with the contact resistance of metal separator plates manufactured in each of the examples and comparative examples.

[0025] In the description of numerical ranges in this specification, the notation “X~Y” indicates X or greater and Y or less, unless otherwise specifically stated. Additionally, “greater than or equal to” may be replaced with “greater than,” and “less than or equal to” may be replaced with “less than.”

[0026] In addition, regarding the numerical ranges described stepwise in this specification, any upper or lower limit value described in any numerical range may be substituted with an upper or lower limit value of another numerical range described stepwise, or may be substituted with a value shown in the examples.

[0027] Hereinafter, a method for manufacturing a metal separator plate according to the present application is described with reference to the attached drawings. The attached drawings are exemplary, and the method for manufacturing a metal separator plate according to the present application is not limited to the attached drawings.

[0028] The method for manufacturing a metal separator plate according to the present application includes a pickling step, a conductive coating step, and a heat treatment step. According to the method for manufacturing a metal separator plate according to the present application, a metal separator plate having excellent electrical conductivity and corrosion resistance simultaneously can be manufactured.

[0029] FIG. 1 is a diagram illustrating, in order to explain a pickling step according to one embodiment of the present application, a base material having impurities and / or an oxide film removed from its surface after pickling. As shown in FIG. 1, the pickling step is a step of pickling the surface of a base material (11) prior to the conductive coating step, comprising, in weight percent, C: greater than 0% and less than or equal to 0.1%, Si: greater than 0% and less than or equal to 0.2%, Mn: greater than 0% and less than or equal to 0.2%, P: greater than 0% and less than or equal to 0.035%, S: greater than 0% and less than or equal to 0.015%, Cr: greater than 28% and less than or equal to 34%, Ti: greater than 0% and less than or equal to 0.45%, and Cu: greater than 0% and less than or equal to 0.45%, with the remainder being Fe and other unavoidable impurities. Specifically, during the manufacturing process of the base material (11), impurities and / or an oxide film are formed on its surface. Since the above impurities and / or oxide film act as insulators, they can reduce the electrical conductivity of the metal separator plate, which can reduce the performance of the hydrogen fuel cell. Therefore, the impurities and / or oxide film formed on the surface of the base material (11) can be removed by pickling.

[0030] In one example, the pickling step may be performed by immersing the base material (11) in a solution containing one or more selected from sulfuric acid, hydrofluoric acid, ammonium fluoride, phosphoric acid, iron sulfate, citric acid hydrate, oxalic acid dihydrate, resin acid, and rosin acid. For example, the pickling may be performed for 1 minute or more and 10 minutes or less, and specifically, for 2 minutes or more and 7 minutes or 3 minutes or more and 4 minutes or less. By including the pickling step, the method for manufacturing the metal separator plate can improve the coating adhesion of the conductive material described later, thereby further improving the electrical conductivity of the metal separator plate. The immersion conditions during the pickling step may use conditions known in the art, so they are not particularly limited.

[0031] The above base material (11) is a material used for a metal separator plate for a fuel cell. For example, as described above, the above base material (11) comprises, in weight%, C: greater than 0% and less than or equal to 0.1%, Si: greater than 0% and less than or equal to 0.2%, Mn: greater than 0% and less than or equal to 0.2%, P: greater than 0% and less than or equal to 0.035%, S: greater than 0% and less than or equal to 0.015%, Cr: greater than 28% and less than or equal to 34%, Ti: greater than 0% and less than or equal to 0.45%, and Cu: greater than 0% and less than or equal to 0.45%, and the remainder consists of Fe and other unavoidable impurities. Specifically, the base material (11) may comprise, in weight percent, C: greater than 0% and less than or equal to 0.1%, Si: greater than 0% and less than or equal to 0.2%, Mn: greater than 0% and less than or equal to 0.2%, P: greater than 0% and less than or equal to 0.035%, S: greater than 0% and less than or equal to 0.015%, Cr: greater than 29% and less than or equal to 33% or less than or equal to 30% and less than or equal to 32%, Ti: greater than 0% and less than or equal to 0.45%, and Cu: greater than 0% and less than or equal to 0.45%, and the remainder may consist of Fe and other unavoidable impurities. By satisfying the aforementioned ranges for the components, particularly chromium, the base material (11) can be used to manufacture a metal separator plate with excellent electrical conductivity and corrosion resistance.

[0032] At this time, the thickness of the base material (11) may be 0.05 mm to 0.5 mm, and specifically, 0.08 mm to 0.4 mm or 0.1 mm to 0.3 mm. In this specification, thickness refers to the average value of the length measured along the thickness direction.

[0033] FIG. 2 is a diagram illustrating an exemplary metal separator plate having a conductive material coated on a pickled substrate to explain a conductive coating step according to one embodiment of the present application. As shown in FIG. 2, the conductive coating step is a step for improving the electrical conductivity of the metal separator plate, and is performed by coating a conductive material (12) on a pickled substrate (11).

[0034] For example, the conductive material (12) may include one or more selected from precious metal materials and carbon. Specifically, the precious metal material may consist of one or more selected from gold (Au), platinum (Pt), ruthenium (Ru), iridium (Ir), ruthenium oxide (RuO2), and iridium oxide (IrO2).

[0035] In one example, the coating method of the conductive material (12) in the conductive coating step is not particularly limited, but various coating methods such as wet electroplating, wet electroless plating, physical vapor deposition (PVD), chemical vapor deposition (CVD), or atomic layer deposition (ALD) can be used.

[0036] The conductive material (12) coated on the base material (11) through the above conductive coating step has a coating density of 5 μg / cm² 2 100 µg / cm² or higher 2 It may be less than, specifically, 6 µg / cm² 2 50 µg / cm² or higher 2 The amount may be less than or equal to the following. The conductive material (12) coated on the base material (11) through the above conductive coating step satisfies the aforementioned range of coating density, thereby improving electrical conductivity without reducing corrosion resistance of the metal separator plate. At this time, the conductive material (12) may be one or more, and the upper limit is not particularly limited.

[0037] FIG. 3 is a diagram illustrating an exemplary metal separator plate having a passivation film formed on the surface of a substrate coated with a conductive material to explain a heat treatment step according to one embodiment of the present application. As shown in FIG. 3, the heat treatment step is a step for improving the corrosion resistance of the metal separator plate, and can be performed by heat treating the substrate (11) coated with a conductive material (12) in the conductive coating step.

[0038] In one example, the heat treatment step may be performed under a vacuum or atmospheric conditions at a temperature of 200°C to 500°C for 10 minutes or more and 120 minutes or less. Specifically, the heat treatment step may be performed under a vacuum or atmospheric conditions at a temperature of 210°C to 400°C or 220°C to 300°C for 20 minutes or more and 90 minutes or 30 minutes or more and 60 minutes or less. By performing the heat treatment step under the aforementioned conditions, a passivation film (13) may be formed on the surface of the base material (11), thereby improving the corrosion resistance of the manufactured metal separator plate. In this specification, the term "vacuum atmosphere" refers to a working environment having a vacuum state. Also, in this specification, the term "atmospheric atmosphere" refers to a working environment having an atmospheric state.

[0039] For example, a metal separator plate manufactured through the above heat treatment step may comprise a base material (11), a conductive material (12) discontinuously formed on the base material (11), and a passivation film (13) formed between the conductive materials (12) on the base material (11). At this time, the conductive material (12) may be exposed to the outside within the passivation film (13). The metal separator plate may have excellent electrical conductivity and corrosion resistance simultaneously by forming the conductive material (12) and the passivation film (13) on the base material (11) in the aforementioned form. In this specification, the term "exposed to the outside" means a state in which at least a portion of the surface of one or more conductive materials may come into contact with external air or other members laminated on the metal separator plate, and "discontinuously formed conductive material" means that one or more conductive materials are arranged at irregular intervals.

[0040] The conductive material (12) may be surrounded by the passivation film (13) if at least one of its surfaces is exposed to the outside, and some of the conductive material may exist within the passivation film (13). At this time, at least one of the conductive material (12) exists within the passivation film (13) at a distance that allows electron transfer between them, and thus, electrical conduction between particles may be possible.

[0041] The above passivation film (13) is a layer formed on the surface of the base material (11) to ensure corrosion resistance of the base material (11).

[0042] In one example, the passivation film (13) may include a metal oxide formed by sintering a component within the aforementioned base material (11). For example, the metal oxide may be an oxide of one or more selected components among the metal components included in the base material (11). Specifically, the metal oxide may be chromium oxide, iron oxide, manganese oxide, silicon oxide, titanium oxide, and / or copper oxide.

[0043] Additionally, the thickness of the passivation film (13) may be 1 nm or more and 10 nm or less. By satisfying the aforementioned range of thickness of the passivation film (13), excellent corrosion resistance can be secured without reducing the electrical conductivity of the metal separator plate. Conversely, if the thickness of the passivation film (13) is less than the lower limit of the aforementioned range, the corrosion resistance of the metal separator plate may be reduced. Furthermore, if the thickness of the passivation film (13) exceeds the upper limit of the aforementioned range, it may be disadvantageous in terms of securing electrical conductivity. In this case, the thickness of the passivation film (13) may refer to the maximum thickness of the passivation film (13) measured from the surface of the base material (11).

[0044] At this time, the conductive material (12) may have a particle size larger than the thickness of the passivation film (13) and may be 5 nm or larger and 30 nm or smaller, specifically 10 nm or larger and 30 nm or smaller. The conductive material (12) may be formed so as to be exposed to the outside from within the passivation film (13) by satisfying the aforementioned range and having a particle size larger than the thickness of the passivation film (13), thereby ensuring electrical conductivity and corrosion resistance in the manufactured metal separator plate.

[0045] The present application also relates to a metal separator plate. The metal separator plate relates to a metal separator plate manufactured according to the method for manufacturing a metal separator plate described above. Since the specific details regarding the metal separator plate described below can be applied in the same way as those described in the method for manufacturing a metal separator plate, they will be omitted.

[0046] The above metal separator plate is manufactured according to the manufacturing method of the metal separator plate described above. By manufacturing the above metal separator plate according to the manufacturing method of the metal separator plate described above, excellent electrical conductivity and corrosion resistance can be achieved simultaneously.

[0047] For example, the metal separator has a current density of 0.5 μA / cm² 2 It may be less than or equal to. In addition, regarding the fact that corrosion resistance is superior the lower the current density of the metal separator, the lower limit is not specifically restricted, but for example, 0.1 μA / cm 2 The above may be the case. The metal separator may have excellent corrosion resistance by having the aforementioned current density. At this time, the current density may be measured based on a cross-section of the metal separator in which the passivation film and the conductive material are formed on the surface of the base material.

[0048] In addition, the metal separator has a contact resistance of 10 mΩ·cm 2It may be less than or equal to. In addition, considering that electrical conductivity is superior the lower the contact resistance of the metal separator, the lower the lower the lower the contact resistance of the metal separator, the lower the lower the lower the lower the lower, but for example, 1 mΩ·cm 2 Above, 3 mΩ·cm 2 Greater than or equal to 5 mΩ·cm 2 It may be more than that. The above metal separator may have excellent electrical conductivity by having the aforementioned contact resistance.

[0049]

[0050] The present application will be described in more detail below through embodiments according to the present application and comparative examples not according to the present application, but the scope of the present application is not limited by the embodiments presented below.

[0051]

[0052] Example 1

[0053] Manufacture of metal separator plates

[0054] A base material (STS 447) with a thickness of 0.1 mm was prepared, comprising 0.05 wt% carbon, 0.1 wt% silicon, 0.1 wt% manganese, 0.018 wt% phosphorus, 0.008 wt% sulfur, 30 wt% chromium, 0.23 wt% titanium, and 0.28 wt% copper or less, with the remainder being iron and other unavoidable impurities. At this time, the surface of the base material was naturally formed by natural oxidation into a very thin Cr2O3 oxide film with a thickness of more than 1 nm and less than 5 nm.

[0055] The above base material was immersed in a solution containing ammonium fluoride for 200 seconds to perform pickling, thereby removing impurities and / or oxide films present on the surface of the above base material.

[0056] Subsequently, the base material from which impurities and / or oxide films have been removed is immersed in a solution containing gold (Au) as a conductive material, and then the conductive material on the base material is 7 μg / cm² 2Electroplating was performed to coat the material with a coating density of 10 nm or more and a particle size of 30 nm or less, and to have a discontinuous shape.

[0057] Subsequently, a metal separator plate was manufactured by heat-treating a substrate coated with the aforementioned conductive material for the temperature and time shown in Table 1 below to form a passivation film in the area not coated with the conductive material.

[0058]

[0059] Example 2

[0060] Manufacture of metal separator plates

[0061] A metal separator plate was manufactured in the same manner as in Example 1, except that heat treatment was performed for the temperature and time shown in Table 1 below.

[0062]

[0063] Comparative Examples 1 and 2

[0064] Manufacture of metal separator plates

[0065] A metal separator plate was manufactured in the same manner as in Example 1, except that a 0.1 mm thick base material (STS 316L) was prepared containing 0.05 wt% carbon, 0.1 wt% silicon, 0.1 wt% manganese, 0.018 wt% phosphorus, 0.008 wt% sulfur, 16 wt% chromium, 0.23 wt% titanium, and 0.28 wt% copper or less, with the remainder being iron and other unavoidable impurities, and heat treatment was performed for the temperature and time shown in Table 1 below.

[0066]

[0067] Comparative Examples 3 and 4

[0068] Manufacture of metal separator plates

[0069] A 0.1 mm thick base material (STS 443) was prepared containing 0.05 wt% carbon, 0.1 wt% silicon, 0.1 wt% manganese, 0.018 wt% phosphorus, 0.008 wt% sulfur, 21 wt% chromium, 0.23 wt% titanium, and 0.28 wt% copper or less, with the remainder being iron and other unavoidable impurities, and a metal separator plate was manufactured in the same manner as in Example 1, except that heat treatment was performed at the temperature and time shown in Table 1 below.

[0070]

[0071] Comparative Examples 5 and 6

[0072] Manufacture of metal separator plates

[0073] A metal separator plate was manufactured in the same manner as in Example 1, except that heat treatment was performed for the temperature and time shown in Table 1 below.

[0074]

[0075] Comparative Example 7

[0076] Manufacture of metal separator plates

[0077] A metal separator plate was manufactured in the same manner as in Example 1, except that pickling treatment was not performed on the surface of the base material and heat treatment was performed for the temperature and time shown in Table 1 below.

[0078] Thickness (nm) of heat-treated passivation film, Temperature (°C), Time (h) Example 1: 230 0.5 5.5 Example 2: 230 16.5 Comparative Example 1: 180 16.5 Comparative Example 2: 230 18.0 Comparative Example 3: 180 16.0 Comparative Example 4: 230 17.5 Comparative Example 5: 180 13.0 Comparative Example 6: 200 13.5 Comparative Example 7: 230 0.5 5.5

[0079]

[0080] Evaluation Example 1. Evaluation of Coating Adhesion

[0081] To evaluate the coating adhesion of the conductive material included in the metal separator plates manufactured in the examples and comparative examples, a tape was adhered to the surface of the metal separator plates and then peeled off at 90° to check whether the conductive material, i.e., gold (Au) particles, detached from the tape, and the results are shown in Table 2 below.

[0082]

[0083] Evaluation Example 2. Current Density Evaluation

[0084] The current density for the metal separator plates prepared in each of the Examples and Comparative Examples was measured by performing the Potentiodynamic polarization method under a simulated environment of a Polymer Electrolyte Fuel Cell (PEFC) from -0.25 V to 1.0 V (Open Circuit Potential), and the results are shown in Table 2 below. Specifically, the current density was determined by loading the metal separator plates prepared in each of the Examples and Comparative Examples into a 0.1 N H2SO4 + 2 ppm HF solution at 80°C, and then 0.6 V SCE It was measured at [location]. At this time, the reaction area of ​​the working electrode was 1.0 cm². 2 It was exposed to [the device], a mercury sulfate electrode (MSE) was used as the reference electrode, and a carbon electrode rod was used as the counter electrode.

[0085]

[0086] Evaluation Example 3. Contact Resistance Evaluation

[0087] The interfacial contact resistance (ICR) was measured for the metal separator plates manufactured in each of the examples and comparative examples, and the results are shown in Table 2 below. Fig. 4 is a diagram exemplarily showing the structure and measurement location of a specimen for measuring the contact resistance of the metal separator plates manufactured in each of the examples and comparative examples. Fig. 5 is a diagram exemplarily showing the structure and measurement location of a dummy specimen for comparison with the contact resistance of the metal separator plates manufactured in each of the examples and comparative examples. As shown in Fig. 5, prior to the actual measurement, two gas diffusion layers (GDL; 2) and one current collector (3) were formed on each of the two sides of the metal separator plate (1) manufactured in each of the examples and comparative examples to prepare the specimen, and then R1, calculated by the following general formula 1, was measured. Subsequently, as shown in FIG. 5, three gas diffusion layers (2) are stacked excluding the metal separator, and one current collector (3) is stacked on each side to produce a dummy specimen, and then a pressure device (68SC5, Instron) is applied to the dummy specimen at 20 N / cm 2 up to 100 N / cm 2 After applying pressure, R2 was measured using the following general formula 2. Then, using the measured R1 and R2, the resistance between the metal separator and the gas diffusion layer (2) was calculated using the following general formula 3. Subsequently, the interfacial contact resistance (ICR) for the gas diffusion layer (2) of the metal separator manufactured in each of the examples and comparative examples was calculated using the calculated resistance between the metal separator and the gas diffusion layer (2).

[0088] [General Formula 1]

[0089] R1= 2R cc-GDL + 2R GDL-GDL + 2R bp-GDL

[0090] In the above general formula 1, bp is a metal separator, GDL is a gas diffusion layer, and cc is a current collector.

[0091] [General Formula 2]

[0092] R2 = 2R cc-GDL + 2R GDL-GDL

[0093] In the above general formula 2, GDL is a gas diffusion layer and cc is a current collector.

[0094] [General Formula 3]

[0095] R bp-GDL = (R1- R2) / 2

[0096] In the above general formula 3, bp is a metal separator and GDL is a gas diffusion layer.

[0097] [General Formula 4]

[0098] ICR = R bp-GDL Х S

[0099] In the above general formula 4, bp is a metal separator, GDL is a gas diffusion layer, and S represents the bp-GDL reaction area.

[0100] Coating Adhesion Evaluation Current Density (µA / cm²) 2 )Contact resistance (mΩ·cm 2 Example 1: No gold (Au) loss 0.510 Example 2: No gold (Au) loss 0.310 Comparative Example 1: No gold (Au) loss 5.610 Comparative Example 2: No gold (Au) loss 3.411 Comparative Example 3: No gold (Au) loss 4.110 Comparative Example 4: No gold (Au) loss 2.610 Comparative Example 5: No gold (Au) loss 2.410 Comparative Example 6: No gold (Au) loss 1.510 Comparative Example 7: Gold (Au) loss 22.519

[0101] Since the metal separator plates prepared in each of Comparative Examples 1 to 4 have a chromium content in the base material below the lower limit of a specific range, it was confirmed that the current density is higher compared to the metal separator plates prepared in each of Examples 1 and 2, as shown in Table 2 above.

[0102] In addition, since the metal separator plates prepared in Comparative Examples 5 and 6, respectively, have a heat treatment temperature below the lower limit of a specific range, it was confirmed that the current density is higher compared to the metal separator plates prepared in Examples 1 and 2, respectively, as shown in Table 2 above.

[0103] In addition, since the metal separator plate manufactured in Comparative Example 7 was not subjected to pickling treatment, it was confirmed that the coating adhesion was reduced as shown in Table 2 above, and as a result, it was confirmed that the current density and contact resistance were higher compared to the metal separator plates manufactured in Examples 1 and 2, respectively.

[0104] Accordingly, unlike the metal separator plates prepared in each of Examples 1 and 2, the metal separator plates prepared in each of Comparative Examples 1 to 7 were found to have a chromium content in the base material that satisfies a specific range, a heat treatment temperature that satisfies a specific range, and a pickling treatment that can simultaneously lower current density and contact resistance, and as a result, it was found that the corrosion resistance and electrical conductivity are excellent at the same time.

[0105] <Explanation of Symbols>

[0106] 1: Metal separator

[0107] 2: Gas diffusion layer

[0108] 3: The whole house

[0109] 11: Base material

[0110] 12: Conductive material

[0111] 13: Passivation film

Claims

1. A pickling step for pickling the surface of a base material comprising, in weight%, C: greater than 0% and less than or equal to 0.1%, Si: greater than 0% and less than or equal to 0.2%, Mn: greater than 0% and less than or equal to 0.2%, P: greater than 0% and less than or equal to 0.035%, S: greater than 0% and less than or equal to 0.015%, Cr: greater than 28% and less than or equal to 34%, Ti: greater than 0% and less than or equal to 0.45%, and Cu: greater than 0% and less than or equal to 0.45%, and the remainder being Fe and other unavoidable impurities; A conductive coating step of coating a conductive material onto a pickled substrate; and A method for manufacturing a metal separator plate comprising a heat treatment step of heat-treating a base material coated with a conductive material.

2. In Paragraph 1, A method for manufacturing a metal separator plate, wherein the above pickling step is performed by immersing the base material in a solution containing one or more selected from sulfuric acid, hydrofluoric acid, ammonium fluoride, phosphoric acid, iron sulfate, citric acid hydrate, oxalic acid dihydrate, resin acid, and rosin acid.

3. In Paragraph 1, The conductive material is a precious metal material composed of one or more selected from gold (Au), platinum (Pt), ruthenium (Ru), iridium (Ir), ruthenium oxide (RuO2), and iridium oxide (IrO2); and A method for manufacturing a metal separator plate containing one or more selected from carbons.

4. In Paragraph 1, The conductive material coated on the substrate through the above conductive coating step has a coating density of 5 μg / cm² 2 Above 100 µg / cm² 2 Method for manufacturing a metal separator plate of the following type.

5. In Paragraph 1, A method for manufacturing a metal separator plate, wherein the above heat treatment step is performed under vacuum or an atmospheric conditions at a temperature of 200°C or higher and 500°C or lower for 10 minutes or more and 120 minutes or less.

6. In Paragraph 1, A method for manufacturing a metal separator plate, wherein the metal separator plate manufactured through the above heat treatment step comprises a base material, a conductive material discontinuously formed on the base material, and a passivation film formed between the conductive materials on the base material.

7. In Paragraph 6, A method for manufacturing a metal separator plate in which the above-mentioned passivation film has a thickness of 1 nm or more and 10 nm or less.

8. In Paragraph 6, A method for manufacturing a metal separator plate in which the conductive material has a particle size larger than the thickness of the passivation film and is 5 nm or more and 30 nm or less.

9. A metal separator plate manufactured according to the method of manufacturing a metal separator plate of any one of claims 1 to 8.

10. In Paragraph 9, Current density is 0.5 μA / cm² 2 Metal separator plate with less than 100 11. In Paragraph 9, Contact resistance is 10 mΩ·cm 2 Metal separator plate with less than 100

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