KR101262590B1 - Fe/cr-cnt metal separator for fuel cell and method of manufacturing the same - Google Patents

Abstract

PURPOSE: An iron and chromium-carbon nanotube(CNT) metal separator and a manufacturing method thereof are provided to be lightweight and to enhance strength, hardness, durability, corrosion resistance, and/or conductivity. CONSTITUTION: An iron and chromium-carbon nanotube metal separator comprises chromium and CNT layers formed on both sides of an iron thin film. A manufacturing method of the iron and chromium-CNT metal separator comprises the following steps: supplying an iron precursor-containing electrolyte to a surface of a conductive mother plate(11) in which a flow path is formed; applying current to a mother plate which is operated by an anode electrode(32) and a cathode which are equipped on the mother plate surface in order to deposit iron on the surface of the conductive mother plate; separating the iron-deposited layer; and forming chromium and CNT layers on both sides of the iron thin plate.

Description

Fe / Cr-CNT METAL SEPARATOR FOR FUEL CELL AND METHOD OF MANUFACTURING THE SAME}

The present invention is excellent in strength, hardness, durability, corrosion resistance and / or electrical conductivity, and the iron thin film metal separator plate formed with chromium and carbon nanotube-containing layers on both sides used as a metal separator plate in the fuel cell ('Fe for fuel cells in the present specification) / Cr-CNT metal separation plate) and a method for manufacturing the same, in particular, the strength, hardness, durability, corrosion resistance and / or the complex flow path shape of the metal separation plate for fuel cells using horizontal electroforming is integrally formed. Or it relates to a fuel cell Fe / Cr-CNT metal separator excellent in electrical conductivity and a method of manufacturing the same.

Traditional methods of collecting energy using fossil fuels are slowly reaching their limits due to global warming, depletion of fuel resources, and environmental pollution. In particular, the prospect is that petroleum fuel will be exhausted in not too long time. In addition, the Energy Climate Convention, represented by the Kyoto Protocol, is compulsoryly required to reduce the emissions of carbon dioxide produced by the burning of fossil fuels. Therefore, the limitation of annual usage of fossil fuel is obvious not only in the present Contracting State but also in the world in the future.

In order to replace fossil fuels, researches on environmentally friendly cars that use electricity as fuels for electric cars, fuel cell cars, and hybrid cars have been actively conducted. Recently, the launch of pure electric vehicles is imminent in commercial use, but the method of operating by charging electricity from the outside has a short driving distance and a long charging time. Fuel cell cars, on the other hand, can generate electricity by supplying hydrogen from the outside, making it easy to recharge fuel, and the driving distance is almost the same as that of gasoline cars.

A fuel cell is a device that converts chemical energy by the reaction of hydrogen and oxygen into electrical energy. A polymer solid electrolyte fuel cell (PEMFC) is mainly used in automobiles. The PEMFC consists of a membrane electrode assembly, a gas diffusion layer (GDL), a gasket, a fastening mechanism, a reactor body, and a separator to move the coolant around the electrolyte membrane.

The separation plate structurally supports a fuel cell, passes a generated current, and plays various roles such as transport of hydrogen and oxygen gas, transport and removal of reaction products, and transport of cooling water for removal of reaction heat. Thus, there are flow paths of very complex shape in the separator plate for the transport of various gases and products and for the cooling water.

In the past, graphite-based separators have been mainly used to satisfy the electrical conductivity, thermal conductivity, gas tightness, and chemical stability required in the separator. However, the graphite-based separator plate is inferior in strength and hermeticity to the metal-based material and is very difficult to form, so the process cost is very high and the productivity is inferior.

Therefore, research on metal separators has been actively conducted in recent years. In particular, the metal separator can be reduced in weight by reducing the thickness of the separator and is characterized by reducing costs. However, when the thickness of the fuel cell separator is thin, it is very difficult to form the material during stamping and there is a problem that it is not easy to obtain the required mechanical strength.

On the other hand, since the separator for fuel cells is used in a sulfuric acid atmosphere where the hydrogen ion concentration is high and the metal is easily corroded at a high temperature, securing corrosion resistance is particularly important. However, a separator including an oxide film having excellent corrosion resistance has poor electrical conductivity. Japanese Patent Laid-Open Publications 2003-276249, and 2003-272653 disclose a technique of very thin gold plating on the surface of a metal separator plate in connection with securing corrosion resistance and electrical conductivity of a metal separator plate for fuel cell. Korean Patent Laid-Open No. 2011-20106 discloses a technique for securing corrosion resistance using precious metals such as gold and platinum. However, these precious metals are expensive and there is a possibility of pinholes due to the thin coating film.

One embodiment of the present invention is to provide a fuel cell Fe / Cr-CNT metal separator excellent in strength, hardness, durability, corrosion resistance and / or electrical conductivity and a method of manufacturing the same.

Another embodiment of the present invention is to provide a Fe / Cr-CNT metal separator plate for a fuel cell and a method for manufacturing the same, in which a complicated flow path shape of the metal separator plate is integrally formed.

Yet another embodiment of the present invention is to provide a thin film of a fuel cell Fe / Cr-CNT metal separation plate and a manufacturing method thereof.

Furthermore, another embodiment of the present invention is to provide a Fe / Cr-CNT metal separator for fuel cells formed by horizontal electroforming and a method of manufacturing the same.

According to a first aspect of the present invention, a fuel cell Fe including an iron thin film and a chromium and carbon nanotube (hereinafter referred to as "CNT")-containing layer formed on both sides of the iron thin film and in which a flow path shape of a separator for a fuel cell is formed A / Cr-CNT metal separator is provided.

According to the second aspect of the present invention, in the first aspect, the iron thin film is provided with a fuel cell Fe / Cr-CNT metal separator plate having a thickness of 30㎛ to 70㎛.

According to a third aspect of the present invention, in the first aspect, the iron thin film is provided with a fuel cell Fe / Cr-CNT metal separator having a nano-sized grain structure.

According to the fourth aspect of the present invention, in the first aspect, the chromium and CNT-containing layer is provided with a fuel cell Fe / Cr-CNT metal separator plate having a thickness of 0.1㎛ 20㎛.

According to a fifth aspect of the present invention, in the first aspect, the chromium and CNT-containing layer is provided with a fuel cell Fe / Cr-CNT metal separator plate containing 10wt% to 50wt% CNTs, residual chromium and other unavoidable impurities. .

According to the sixth aspect of the present invention,

Supplying an electrolyte solution containing an iron precursor to a surface of a conductive mother plate having a flow path shape of a separator plate for a fuel cell horizontally supplied in a predetermined direction;

An electric current is applied to the anode plate and the cathode which are spaced apart from the surface of the mother plate where the flow path shape of the fuel cell separation plate is formed so that iron is electrodeposited on the surface of the conductive mother plate where the flow path shape of the fuel cell separation plate is formed. Making;

Separating the iron electrodeposition layer formed by electrodeposition; And

Provided is a method for manufacturing a Fe / Cr-CNT metal separator plate for fuel cells, including forming chromium and CNT-containing layers on both sides of an iron thin film obtained by separation of the iron electrodeposition layer.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the fuel cell separation plate is provided with a fuel cell Fe / Cr-CNT metal separation plate manufacturing method is formed on one side or both sides of the conductive mother plate. do.

According to an eighth aspect of the present invention, in the sixth aspect of the present invention, the iron precursor is at least one selected from the group consisting of iron sulfate, iron chloride, iron nitrate, and iron sulfamate, for separating a Fe / Cr-CNT metal for fuel cell. A plate manufacturing method is provided.

According to a ninth aspect of the present invention, in the sixth aspect of the present invention, the forming of the chromium and CNT-containing layer may be performed by a cathode electrophoresis method using a suspension containing chromium precursor and CNTs. Provided is a method for producing a metal separator.

In the Fe / Cr-CNT metal separator plate for fuel cells according to one embodiment of the present invention, the flow path shape of the complex fuel cell separator plate is integrally formed. Fe / Cr-CNT metal separators for fuel cells are thin, yet light, and have excellent strength, hardness, durability, corrosion resistance and / or electrical conductivity, particularly excellent corrosion resistance and electrical conductivity. The Fe / Cr-CNT metal separator for fuel cell is manufactured by horizontal electroforming using a base plate in which the flow path shape of the complex fuel cell separator is formed, whereby the flow path shape formed on the mother plate is transferred to the iron thin film so that the complicated flow path shape is integrated. It is formed continuously. In addition, not only the iron thin film is formed to a uniform thickness by the horizontal electroforming method, it is easy to control the thickness and mass production is possible.

1 is a view schematically showing an example of the configuration of a horizontal electric casting apparatus used for manufacturing a Fe / Cr-CNT metal separator plate for a fuel cell according to an embodiment of the present invention.
2 is a photograph of a metal separator plate for a fuel cell in which a general flow path shape is formed.

The inventors of the present invention have completed the present invention in view of the fact that the flow path shape of the fuel cell separator formed on the mother plate can be transferred to the Fe / Cr-CNT metal separator for fuel cell.

The Fe / Cr-CNT metal separator for fuel cells according to one embodiment of the present invention includes an iron thin film and a chromium and carbon nanotube-containing layer (hereinafter, also referred to as a 'Cr-CNT layer') on both sides of the iron thin film. The fuel cell separator has a flow path shape. The iron thin film has a thickness of 30 μm to 70 μm and the Cr-CNT layers formed on both sides of the iron thin film have a thickness of 0.1 μm to 20 μm, respectively. In terms of handling and cost competitiveness in the fuel cell manufacturing process, the iron electrodeposition layer preferably has a thickness of 30 μm to 70 μm. The thickness of the Cr-CNT layer is preferably 0.1 µm to 20 µm in consideration of sufficient iron thin film coverage of the Cr-CNT layer and to prevent peeling and cracking caused by the increase in the thickness of the Cr-CNT layer. The Cr-CNT layer contains 10wt% to 50wt% CNT, balance chromium and other unavoidable impurities.

As such, the Fe / Cr-CNT metal separator for fuel cells is an ultrathin film, but the iron thin film has a nanocrystalline structure, and has very excellent mechanical strength. The size of the nanocrystals may range from 1 nm to 10 nm, for example. The Fe / Cr-CNT metal separation plate including the Cr-CNT layer having the above composition has excellent corrosion resistance by the Cr-CNT layer and very excellent heat dissipation, electrical conductivity and / or mechanical properties by the CNT. In addition, the Fe / Cr-CNT metal separator for fuel cells is not only excellent in strength and / or hardness, but also flexible, so that cracks or fractures due to physical impact do not easily occur, thereby ensuring excellent durability.

According to another embodiment of the present invention, there is provided a method for manufacturing a Fe / Cr-CNT metal separator for a fuel cell by horizontal electroforming.

In the case of manufacturing a metal separator plate for fuel cell by the conventional rolling method, the heat treatment and rolling process must be performed several times in order to reduce the thickness of the metal separator plate. It is difficult to maintain a constant shape. In addition, problems such as thickness variation, surface roughness are not constant, and edge cracks are generated, resulting in high manufacturing costs and difficulty in producing a wide metal electrodeposition layer.

On the other hand, when the metal electrodeposition layer is manufactured by the electroforming method using the drum cell, it is important to manage the surface of the drum in order to manufacture a thin film having a uniform thickness and surface shape. Operation is difficult. In addition, since the area of the drum surface immersed in the electrolyte determines the electrodeposition speed, the production speed is limited according to the size of the drum used for the pole, and the cost of providing a large drum is high, and thus, the limitation of replacing the drum is disadvantageous. Has Furthermore, in order to increase the production rate, the electrolyte flow rate between the anode and the cathode must be increased, but the electrolyte flow rate gradually decreases because the shape between the anode and the cathode is curved.

However, in one embodiment of the present invention, a continuous thin film of a fuel cell Fe / Cr-CNT metal separator plate having a uniform flow path shape of a complex fuel cell cell separator plate is formed by using a horizontal electroforming method capable of using a high speed flow field. It can be manufactured with excellent productivity.

Fe / Cr-CNT metal separation plate manufacturing method for a fuel cell by horizontal electroforming according to an embodiment of the present invention, the step of supplying an electrolyte containing an iron precursor to the surface of the conductive mother plate horizontally supplied in a predetermined direction, the conductivity Applying a current so that iron is electrodeposited on the surface of the mother plate, separating the iron electrodeposition layer formed by electrodeposition of iron, and forming a Cr-CNT layer on both sides of the iron thin film obtained by separating the iron electrodeposition layer.

In forming the Fe / Cr-CNT metal separator plate for fuel cell by horizontal electroforming, any base plate having flexibility and conductivity may be used without particular limitation. In such a mother plate, an oxide film, specifically a metal oxide film, is preferably formed on one or both surfaces. Although not limited to this as the metal oxide film, titanium oxide, chromium oxide, lithium oxide, iridium oxide, platinum oxide, etc. can be formed. Specifically, for example, a metal substrate such as stainless steel or titanium in which the metal oxide film is formed may be used. Also for example, plastic substrates having conductivity and flexibility can be used. Specifically, the conductivity and flexibility for plastic substrates can be imparted by generally known methods of forming metal oxides and / or metal layers. For example, a plastic substrate on which the metal oxide film and / or platinum layer is formed may be used.

When the iron electrodeposition layer formed by electrodeposition to the mother board is firmly bonded, it is difficult to separate the iron electrodeposition layer from the mother board, so that an oxide film is preferably formed on the mother board surface. Since the adhesion of the iron electrodeposition layer to the mother plate surface is weakened by the oxide film on the mother plate surface, the iron electrodeposition layer can be easily peeled from the mother plate.

The flow path shape of the separator for fuel cell is formed on the surface of the mother plate. The flow path shape of the surface of the mother plate is not particularly limited, and may be any flow path shape generally formed in the separator for fuel cell known in the art. Flow path forming method for the base plate The flow path can be formed in the base plate by any method known in the art, for example, it can be formed by pressing or stamping. The flow path shape may be formed on one side or both sides of the mother plate. In terms of productivity, it is preferable to obtain a thin iron film by forming a flow path shape on both sides of the mother plate and electrodepositing iron on both surfaces where the flow path shape is formed.

The base plate supplied horizontally in the predetermined direction may include optionally and additionally cleaning the surface of the base plate as needed before the electrodeposition process. The washing of the surface of the mother plate is not particularly limited and can be performed using an acidic solution or water. The acidic solution can be any acidic solution generally known for use in substrate cleaning. Thereafter, the mother board can be dried by blowing high pressure air, hot gas, or heating the mother board.

In addition, the step of polishing the base plate to adjust the surface roughness or even surface of the base plate prior to the washing of the base plate may further include if necessary. Polishing can be performed by any method generally known in the art, and is not specifically limited. However, for example, mechanical polishing such as polishing, chemical polishing such as etching, and chemical mechanical polishing such as CMP (Chemical Mechanical Polishing) method mainly used in semiconductor processes. The chemical polishing, mechanical polishing and chemical mechanical polishing means may be used alone or in combination thereof.

Such base plates are continuously supplied into the horizontal electroforming cell and are supplied in a constant direction. Herein, the term 'electro-casting cell' refers to a unit in which an electrolyte is supplied onto a mother plate so that metal ions, specifically, iron ions are electrodeposited on the surface of the mother plate where a flow path shape is formed by an electrolytic precipitation reaction to form an iron electrodeposition layer. It can be defined as a battery. In addition, the term “constant direction” means that the advancing direction of the mother board does not change until at least the horizontal cell exits the horizontal cell after the mother plate is supplied into the electroforming cell and proceeds in one direction. In this specification, the advancing direction of the mother plate may be referred to as 'horizontal direction' or simply 'horizontal' in some cases. Furthermore, the mother plate advances the electroforming cell in the horizontal direction, whereby metal ions (iron ions) in the electrolyte The electroforming cell is also referred to as a 'horizontal cell' to indicate that it is electrolytically deposited on the mother plate.

For the continuous supply of the mother board, the mother board is not limited to this, but the mother board can be fed into the horizontal cell in which the coil is wound in the form of a coil. It can be supplied continuously. At this time, if necessary, the rear end of the preceding base plate and the leading end of the following base plate can be joined by a predetermined bonding method such as welding and continuously supplied. Furthermore, in order to easily join, each terminal joined can also be processed to a suitable shape.

The base plate may be supplied horizontally into the horizontal cell by a pair of conductor rolls which contact the width edge of the base plate to transfer the base plate into the horizontal cell. At this time, the electrolytic solution may be supplied to one side of the mother plate supplied into the horizontal cell to perform electroforming on one side, and the electrolytic deposition of iron on both sides to increase the production rate of the iron electrodeposition layer. You can. The shape of the fuel cell separator flow path may or may not be formed on the surface of the mother plate to which the electrolyte is supplied. However, in order to obtain the iron thin film in which the flow path shape of the present invention is integrally formed, the fuel cell separation membrane flow path shape must be formed on the surface of the mother plate.

When the mother plate is supplied into the horizontal cell as described above, the electrolyte is supplied to one or both sides of the mother plate through the electrolyte supply nozzle, and the electrolyte is moved through the horizontal flow path formed by the mother plate and the anode electrode, thereby applying the current of the cathode electrode. Electrolytic precipitation by the action of the mother plate and the anode electrode, which plays a role, causes iron ions to precipitate on the surface of the mother plate to form an iron electrodeposition layer.

In the case of the conventional drum type electroforming cell, the mother plate shape provided as the cathode has a curvature in the shape of a drum, so that the flow path of the electrolyte also forms a curvature, and as a result, the flow rate of the electrolyte is gradually lowered, thereby lowering the electrodeposition rate, and obtaining the electrodeposited metal. There is a problem that the thickness of the layer becomes nonuniform. Furthermore, in the case of forming an oxide film on the drum surface, there is a problem that the management of the electrolyte solution is not easy because impurities are introduced into the electrolyte solution during this process.

However, in the case of the horizontal cell, since the flow path is formed horizontally, the electrolyte can be supplied at a high speed without decreasing the flow rate of the electrolyte, thereby increasing the electrodeposition rate of the iron ions. The supply rate of electrolyte (Re, Reynolds number) can be supplied up to 5,000, and the relative speed can be appropriately increased or decreased depending on the progress of the mother plate. In addition, depending on the state of the electrodeposition reaction, the electrolyte may be supplied at a flow rate of laminar flow (the flow of fluid supplied in a straight line without shaking the water, having straightness), and a high speed turbulence (water stem) after a stable electrodeposition reaction is formed. Can be supplied at a flow rate). If the flow rate of electrolyte is increased during initial electrodeposition, electrodeposition layer may be separated and electrodeposition may fail. If electrodeposition layer grows to several micro level, adhesion is improved by stress generated in electrodeposited layer and high speed flow field can be used. It is. On the other hand, when using a high speed flow field, the fluid supply speed region is preferably supplied at a flow rate below the surface tension between the electrodeposition layer and the mother plate, and the electrolyte is supplied at a flow rate beyond the surface tension between the electrodeposition layer and the mother plate. When supplied, the shear stress between the flow field and the electrodeposited layer due to the supply of the electrolyte exceeds the surface tension between the electrodeposited layer and the mother plate, thereby causing peeling of the electrodeposited layer.

The electrolyte is supplied to the surface of the mother plate through the nozzle from the electrolytic cell containing the electrolyte, such electrolyte may be supplied in the same direction and in the opposite direction with respect to the traveling direction of the mother plate. By doing in this way, the electrodeposition rate of an iron component with respect to a surface of a mother board can be raised further.

On the other hand, the electrolyte used for electrodeposition can be recovered by electrolyte storage tank again as needed. At this time, since the recovered electrolyte is iron ion is consumed for electrodeposition, the iron ion concentration in the electrolyte storage tank will be lower than the concentration required for electrodeposition, it can be adjusted to a predetermined iron ion concentration by appropriately supplementing iron ions.

The electrolyte solution contains an iron precursor to form an iron electrodeposition layer. The electrolyte is generally an aqueous solution containing a precursor of a metal to be plated, and other additives such as optional conduction aids, complexing agents and stress relieving agents, if necessary, so long as the electrolyte contains an iron precursor, the composition of the electrolyte is particularly The present invention is not limited thereto, and may be any electrolyte solution commonly used for electroforming. The iron precursor is not limited thereto, but may be, for example, at least one selected from the group consisting of iron sulfate, iron chloride, iron nitrate, and iron sulfamate. The content of the iron precursor in the electrolyte solution is not particularly limited, and may be appropriately adjusted according to the moving speed of the mother plate, the electrolyte supply speed, and the thickness of the iron electrodeposition layer (iron thin film). However, for example, the electrolyte may include 250 g to 300 g of iron precursor per 1 L of water, and other additives such as conventional conduction aids, complexing agents, and stress relaxation agents, if necessary.

The electrodeposition process through the horizontal cell as described above may be performed a plurality of times in succession. As described above, when the electrodeposition process through the horizontal cell is performed a plurality of times, the thickness of the iron electrodeposition layer obtained by electrodeposition in each horizontal cell can be increased, and the thickness of the iron electrodeposition layer can be controlled as needed. Even if the mother plate is supplied at a higher speed, an iron electrodeposition layer having a desired thickness can be obtained, thereby improving productivity. When a plurality of electrodeposition processes are performed, the process conditions and the composition of the electrolyte solution may be the same or different in the plurality of electrodeposition processes. The number of repetitions of the electrodeposition process is not limited, and may be appropriately selected depending on the desired degree of electrodeposition.

On the other hand, since the electrolyte may remain on the surface of the iron electrodeposition layer formed on the mother plate, it is preferable to optionally wash the surface of the iron electrodeposition layer as necessary. Such washing may be performed using an acidic solution or water, and in addition, a flexible brush or the like may be used to effectively remove the residual electrolyte. The acidic solution may be any one known to be usable for metal surface cleaning, and is not particularly limited. Such washing may be performed in a state where an electrodeposition layer is formed by electrodeposition on the mother plate, but the iron thin film may be washed after separating the iron electrodeposition layer from the mother plate. After washing, high pressure air or hot gas may be injected onto the iron electrodeposition layer or the iron thin film surface, or the iron electrodeposition layer or the iron thin film may be dried by heating or the like.

The iron electrodeposition layer is separated from the mother plate to obtain an iron thin film. The iron thin film may include inevitable impurities, but may preferably be a pure iron thin film. The unavoidable impurities may be inevitably incorporated from raw materials or the surrounding environment in a conventional manufacturing process, and thus cannot be excluded. Since these impurities are known to those skilled in the art, not all of them are specifically mentioned herein.

The difference in shear stress between the base plate and the iron electrodeposition layer can be used to separate the iron electrodeposition layer from the base plate. Since the iron electrodeposition layer is bonded by the surface tension with respect to the oxide film on the mother plate, it can be easily separated by the shear stress difference. Separation of the iron electrodeposition layer due to such a shear stress difference can be carried out by passing through a plurality of rollers. Furthermore, it can be separated by the shear force due to the difference in the moving speed of the iron electrodeposition layer and the moving speed of the mother plate. On the other hand, when electrodeposition is performed on both sides of the mother plate, the upper and lower iron electrodeposition layers may be separated at the same time, or may be separated by giving a time difference.

Cr-CNT layers are formed on both sides of the separated thin iron film. The Cr-CNT layer contains 10wt% to 50wt% CNT, balance chromium and other unavoidable impurities. The unavoidable impurities may be inevitably incorporated from raw materials or the surrounding environment in a conventional manufacturing process, and thus cannot be excluded. Since these impurities are known to those skilled in the art, not all of them are specifically mentioned herein.

The Cr-CNT layer having the above composition is electrodeposited into the amorphous thin film on the iron thin film, and the amorphous tissue exhibits excellent corrosion resistance. In addition, the Cr-CNT layer exhibits excellent electrical conductivity.

The Cr-CNT layer may be formed by, for example, depositing chromium and CNT on both sides of the iron thin film by electrophoresis. CNT (carbon nanoparticles) has a problem that it is difficult to uniformly dispersed in a material or metal having excellent heat dissipation, electrical conductivity and mechanical properties. However, in the method according to the embodiment of the present invention, CNT and chromium are uniformly deposited on the iron thin film by electrochemical electrophoresis (EPD) to form a Cr-CNT layer. Electrophoresis is based on the principle that the charged particles are deposited toward the opposite side of the charge when an electric field is applied to a suspension containing charged particles, and there are cathodic and anodic processes. In particular, in the case of the cathode method, since CNTs are deposited on the cathode by electrophoresis, there is an advantage that the electroforming can be performed continuously.

In the method according to one embodiment of the present invention, the surface of the CNT is treated with a positive charge so that chromium and CNT are simultaneously deposited on the iron thin film. Specifically, it is preferable to use CNT in which an amine group is introduced on the surface. CNT in which an amine group is introduced into the surface can be obtained, for example, by surface treatment of CNT with polyethyleneimine (PEI). Treatment of CNT surfaces with PEI is common in the art and is not described in detail.

CNT introduced with an amine group on the surface forms a Cr-CNT layer having good interfacial bonding force with chromium in the iron thin film due to the affinity with the high metal component of the amine group. Furthermore, there is an advantage that the Cr-CNT layer is uniformly deposited in a large area by the cathode electrophoresis method. The suspension used in the electrophoresis method for forming the Cr-CNT layer is not particularly limited as long as it includes the chromium precursor and the CNT as an aqueous solution containing the chromium precursor and the CNT. The content of chromium precursor and CNT in the suspension can be appropriately adjusted according to the composition ratio of Cr and CNT in the Cr-CNT layer, for example, 100 g / l to 250 g / l chromium precursor and 1 g / l to 15 g / CNT. It can include l. The chromium precursor is not limited thereto, but, for example, chromium oxide, chromium sulfate, chromium nitrate, and potassium chromium sulfate may be used as one kind or two or more kinds thereof. Further, the suspension may contain other additives such as conduction aids, complexing agents and stress relieving agents that are generally formulated, optionally in amounts generally used in the art, as needed.

On the other hand, since the suspension etc. may remain in the formed Cr-CNT layer, it is preferable to wash arbitrarily as needed. It can be washed with acidic solution or water. The acidic solution may be any one known to be usable for metal surface cleaning, and is not particularly limited. After washing, high pressure air or hot gas may be injected or optionally dried by heating or the like.

Thereafter, a thin film (hereinafter referred to as a 'Fe / Cr-CNT thin film' or a 'Fe / Cr-CNT metal separator') having a Cr-CNT layer formed on both surfaces of the Fe thin film may be wound. . It can cut suitably according to the winding amount. The prepared Fe / Cr-CNT thin film can be used as a metal separator plate for fuel cells. On the other hand, the base plate from which the iron electrodeposition layer is separated can be wound and reused as the base plate. However, since the separated mother plate may have electrolyte or other impurities in the electrodeposition process, it is preferable to keep the surface of the mother plate clean by drying after washing. Furthermore, when the mother plate is bonded for continuous supply of the mother plate, the mother plate may be cut to an appropriate length according to the amount of winding of the mother plate, and in this case, it is preferable to cut based on the bonding portion.

In the fuel cell Fe / Cr-CNT metal separator manufacturing process, the process conditions, the electrolyte composition and the suspension composition are not particularly limited, and may be performed in a range generally performed in the electroforming and electrophoretic processes.

Hereinafter, a method for manufacturing a Fe / Cr-CNT metal separator for a fuel cell by a horizontal electroforming method according to an embodiment of the present invention will be described with reference to the horizontal electroforming apparatus of FIG. 1. FIG. 1 is not limited to FIG. 1 as an example of a horizontal pole apparatus, which is used to manufacture a Fe / Cr-CNT metal separator plate for a fuel cell by a horizontal electroforming method according to one embodiment of the present invention.

The horizontal pole device 100 includes a mother plate supply device 10, the horizontal cell 30, the electrolyte supply device and the iron thin film separator (51).

The mother plate feeding device 10 may include a winding machine for supplying the mother plate 11. In order to continuously supply the base plate 11, a plurality of the winding machines may be installed, and when the base plate 11 is exhausted in one winding machine, a new base plate 11 may be supplied from another winding machine. For the continuous supply of such base plates 11, optionally and additionally, a joining device 12, such as welding, for joining the ends of the pre-supplied base plate 11 and the tip of the base plate 11 to be provided next is optionally required. It may include.

The flow path shape of the separator plate for a fuel cell is formed on at least one surface of the base plate, preferably on both sides, and the flow path shape of the base plate surface is transferred to the iron electrodeposition layer deposited on the surface of the base plate by electroforming.

On the other hand, the electrodeposition layer electrodeposited on the base plate 11 transfers the surface roughness of the base plate 11, and therefore is almost identically expressed in the iron thin film from which the surface roughness of the base plate 11 is obtained. Therefore, the grinding means 13 for adjusting the surface roughness of the base plate 11 may be further included as necessary. Such polishing means 13 is not particularly limited, and may include mechanical polishing such as polishing, chemical polishing such as etching, and chemical mechanical polishing such as a CMP method mainly used in semiconductor processes. The chemical polishing, mechanical polishing and chemical mechanical polishing means may be used alone or in combination thereof. By this polishing means, the surface of the base plate 11 can be arbitrarily evenly and conveniently adjusted to the desired surface roughness as necessary.

Furthermore, since impurities may be present on the surface of the mother plate 11, additional washing may be necessary as necessary to remove them, and thus, the pre-cleaning device 14 may be additionally included as necessary. The cleaning of the surface of the base plate 11 may use an acid solution such as diluted hydrochloric acid or sulfuric acid or water. After washing, a drying apparatus (not shown) for drying the base plate 11 may be further included as necessary. Drying can be performed by adding air at high pressure, or adding a hot gas, or can also be performed by heating the base plate 11.

The horizontal pole device 100 includes a horizontal cell 30 separated from the mother plate feeding device 10. In the case of a conventional electroplating apparatus using a drum, there is a problem that foreign matters generated during polishing to control the surface roughness on the drum surface are contaminated with the electrolyte and contaminate the electrolyte. Since it is separated, contamination of the electrolyte solution can be prevented.

The horizontal cell 30 is spaced apart at regular intervals from the conductor rolls 31 and 31 ′, which serve to transfer the base plate 11 and connect the cathode power, and the base plate 11. Currents having negative (+) and positive (+) charges are respectively applied to the anode electrode 32, the conductive rolls 31, 31 ′, and the anode electrode 32 disposed on one or both surfaces of the mother plate 11. And a current supply device 33 for supplying and an electrolyte supply device for receiving the electrolyte solution.

The conductor rolls 31 and 31 'function as a transfer means for transporting the base plate 11 into the horizontal cell 30 and discharging it from the horizontal cell 30, and supplying current with the base plate 11. The cathode power source of the device 33 is connected to perform an electrolytic precipitation reaction in which iron ions are deposited on the base plate 11 by an electrolytic reaction between the anode electrode 32 and the base plate 11. These conductor rolls 31 and 31 'contact the two edges in the width direction of the base plate 11 to transfer the base plate 11 into the horizontal cell 30 and discharge it from the horizontal cell 30.

Since the mother plate 11 uses a flexible conductive mother plate, a drooping phenomenon may occur when passing through the horizontal cell 30. In this case, the gap between the mother plate 31 and the anode electrode 32 is changed. This may cause a difference in current density, and thus an iron thin film of uniform thickness may not be obtained. Accordingly, in order to prevent the base plate 11 from sagging, the rotational speeds of the inlet conductor roll 31 and the outlet conductor roll 31 'are varied, that is, the outlet conductor roll 31' is rotated. It is preferable to make the speed faster than the rotational speed of the inlet-side conductor roll 31 to prevent sagging due to the weight of the mother plate.

Meanwhile, the conductive rolls 31 and 31 ′ transmit current supplied from the current supply device 33 to the base plate 11 so that the base plate 11 can function as a cathode electrode. It is possible to cause the electrolytic precipitation reaction by the action of 32).

The anode electrode 32 may be spaced apart from the base plate 11 at regular intervals on one or both sides of the base plate 11 in order to cause an iron electrolytic precipitation reaction to the base plate 11. Preferably, the anode electrode 32 may be spaced apart from each other on the base plate 11. The anode electrode 32 may be spaced apart from the base plate 11 with or without a flow path shape, but in order to obtain a metal separation plate having a flow path shape, the anode electrode 32 should be installed on the side of the base plate 11 with a flow path shape. .

Since the anode electrode 32 and the mother plate 11 are spaced apart from each other, a flow path through which an electrolyte is supplied and distributed therebetween is provided, and as described above, the cathode electrode 32 and the anode electrode 32 are actuated by the action of the cathode electrode 32. An electrolytic reaction may occur in which iron ions in the electrolyte are electrolytically deposited on the mother plate. On the other hand, by supplying the electrolyte at a high speed, it is possible to increase the electrodeposition rate of the iron ions to the surface of the base plate (11). In the case of a conventional pole cell using a pole, because the flow path is formed curvature, the flow rate of the electrolyte gradually becomes a problem that the electrodeposition speed is lowered. However, in the method according to the present invention, the flow path of the electrolyte solution is formed in a plane, thereby preventing a decrease in the speed of the flow field with respect to the supply of the electrolyte solution.

The current supply device 33 supplies (-) current and (+) current to the conductive rolls 31, 31 'and the anode electrode 32, respectively, as long as it can be applied without particular limitation. As applicable to the present invention, a detailed description thereof will be omitted.

The electrolyte supply apparatus includes an electrolyte storage tank 34 for storing and containing an electrolyte solution and an electrolyte supply nozzle 38 for supplying an electrolyte solution to the surface of the base plate 11. The electrolyte is transferred from the electrolyte reservoir 34 to the electrolyte supply nozzle 38 through an electrolyte supply pipe. The electrolyte supply nozzle 38 may be installed to be supplied only to one surface of the mother plate 11, or may be installed on both sides of the electrolyte supply to both surfaces of the mother plate 11. However, in order to obtain the iron thin film having the flow path shape of the separator for fuel cell, an electrolyte solution must be supplied to the surface of the base plate on which the flow path shape is formed.

The electrolyte solution contains 250 to 300 g / l of an iron precursor selected from the group consisting of, for example, iron sulfate, iron chloride, iron nitrate and iron sulfamate, as described above, and optionally any conductive aids, complexing agents and stresses. Other additives, such as emollients, may be further included, if desired, in amounts generally used in the art.

Meanwhile, the electrolyte storage tank 34 includes an electrolyte heater 35 for heating the electrolyte, an electrolyte filter 36 for removing impurities such as sludge included in the electrolyte, and an electrolyte pump 37 for supplying the electrolyte to the horizontal cell. Etc. may be further included as needed.

On the other hand, compared to the center of the base plate 11, the current density may be relatively lower at both edges in the width direction in some cases. At the edge of the base plate 11, the electrodeposited amount of precipitated iron decreases so that the thickness of the iron thin film is relatively low. It may become thin and a thin Fe film may not be obtained as a whole. In this case, when the obtained iron electrodeposition layer is separated from the mother plate 11, there is a possibility that the edge of the iron thin film is torn and a defect occurs. In order to make the iron thin film separated from the base plate 11 to have a uniform thickness, a post-treatment process of cutting thin edges is required. Therefore, it is necessary to prevent the precipitation of iron and nickel in the edge portion of the mother plate to prevent the thickness variation, for this purpose it may be provided with an edge mask (not shown) so that the electrolyte is not supplied to the edge of the mother plate. . By providing such an edge mask, formation of a thin iron electrodeposition layer at the edge of the base plate 11 is prevented.

The electrolyte supply nozzle 38 supplies the electrolyte at a high speed through the horizontal passage formed by the mother plate 11 and the anode electrode 32. In this case, the electrolyte may be installed such that the electrolyte is supplied in the same direction and in the opposite direction to the traveling direction of the base plate 11 with respect to the electrolyte supply nozzle 38. By doing in this way, the effect of electrodeposition substantially can be acquired. That is, the electrolyte solution supplied in the opposite direction can obtain the effect of primary electrodeposition, in which a relatively small amount of short time for the electrolyte solution to contact the mother plate 11 is electrodeposited due to the difference in relative speed with the mother plate 11, and the same. The electrolytic solution supplied in the direction may contact the base plate 11 for a longer time, thereby obtaining the effect of secondary electrodeposition in which a relatively large amount of electrodeposits are electrodeposited compared to the primary electrodeposition.

The horizontal cells 30 as described above may be provided in plural in series in the traveling direction of the mother plate 11. Even if a plurality of horizontal cells 30 are installed, the electrodeposition layer is not separated from the mother plate 11 during movement by being disposed in series in the traveling direction of the mother plate 11. By installing a plurality of horizontal cells, an electrodeposition layer having a desired thickness can be formed on the base plate 11 even though the base plate is advanced at a higher speed while reducing the electrodeposition amount through one cell, thereby improving the productivity of the iron thin film. have. Electrodeposition conditions and electrolyte solutions in the plurality of horizontal cells 30 may be the same or different.

For example, the first horizontal cell and the second horizontal cell are installed, electrodeposited iron on the mother plate in the first horizontal cell, and further iron electrodeposited on the electrodeposition layer electrodeposited on the mother plate in the second horizontal cell. The layers can be electrodeposited. Thus, by installing a plurality of horizontal cells, even if the mother plate advances at a higher speed while reducing the amount of electrodeposition through one cell, an electrodeposition layer having a desired thickness can be formed on the mother plate, thereby improving the productivity of the iron electrodeposition layer. have. Electrodeposition conditions and electrolyte composition in the first horizontal cell and the second horizontal cell may be the same or different.

The base plate 11 in which the electrodeposition layer is formed is discharged through the outlet side roll 31 ', and after discharge, the iron electrode layer is separated from the base plate 11 by the iron thin film separator 51. Get Since the iron thin film is coupled by surface tension on the base plate 11 having an oxide film formed on the surface thereof, the iron thin film may be separated by a difference in shear force between the iron thin film and the base plate 11. Therefore, the iron thin film separator 51 is preferably capable of imparting shear stress for separating the iron thin film from the mother plate 11, for example, may be provided with a plurality of rollers. In addition, the difference in the moving speed of the iron thin film and the mother plate 11 may be separated by giving a time difference between the upper and lower iron thin film.

The iron thin film may have a thickness of 30 μm to 70 μm. In addition, the iron thin film may have, for example, a nanocrystalline structure having a size ranging from 1 nm to 10 nm.

Cr-CNT layers are formed on both sides of the iron thin film obtained by separation by the iron electrodeposition layer separator 51 in the electrophoretic apparatus P. The Cr-CNT layer may have a thickness of 0.1 μm to 20 μm. The electrophoretic device (P) may be any electrophoretic device generally known to be used for electrophoresis in the art, and is not particularly limited. The suspension is, as described above, for example 100 g / l to 250 g / l of at least one chromium precursor selected from the group consisting of chromium oxide, chromium sulfate, chromium nitrate, and potassium chromium sulfate and 1 g / l to 15 CNTs. g / l and other additives such as conducting aids, complexing agents and stress relief agents, which are optionally optionally formulated as needed, may be included in amounts generally used in the art.

By forming a Cr-CNT layer on both sides of the iron thin film, a Fe-Cr-CNT metal separator for a fuel cell according to one embodiment of the present invention is obtained. The iron thin film having the Cr-CNT layer formed thereon may be optionally washed and dried as necessary to remove a plating solution that may remain on the surface of the Cr-CNT layer. Thus, it may optionally further comprise a washing device and / or a drying device (not shown) as necessary. The cleaning device is a device for removing an acid solution such as hydrochloric acid and / or sulfuric acid diluted with an electrolyte solution and foreign matter that may be present on the surface of a metal, and using a conventional device such as a high pressure spray. The drying apparatus may be an injector for injecting air at a high pressure or injecting hot gas, or may be a heating apparatus for heating and drying.

The fuel cell Fe / Cr-CNT metal separation plate 50 and the base plate 11 on which the iron electrodeposition layer is peeled off are respectively wound by the metal separation plate winding device 55 and the mother plate winding device 72. The winding devices 55 and 72 can be, for example, cylindrical winding machines. The winding devices 55 and 72 may be wound in an appropriate amount according to the winding amount, and may be wound and wound around another winding machine. Therefore, any additional fuel cell Fe / Cr-CNT metal separator cutting device 54 and mother plate cutting device 71 may be further included as necessary for the cutting. The cutting is more preferably cut at the bonding site of the mother plate.

On the other hand, the horizontal pole device 100 is discharged from the horizontal cell 30 as necessary before or after separating the iron thin film, and if necessary after the treatment of the base plate, iron electrodeposition layer and / or iron thin film The device may further be provided. Such a post-treatment device may include a post-cleaning device 52, and / or a drying device (not shown).

The cleaning device 52 is a device for removing by using an acidic solution such as hydrochloric acid or sulfuric acid diluted with electrolyte and foreign substances that may be present on the surface of the base plate 11, the iron electrodeposition layer, and / or the iron thin film, Conventional apparatuses, such as a high pressure spray, can be used. The drying apparatus may be an injector which injects air at high pressure or injects hot gas after washing to remove washing liquid, etc. present on the surface of the base plate 11, the iron electrodeposition layer, and / or the iron thin film, or It may be a heating device for heating and drying.

In the manufacturing process of the Fe / Cr-CNT metal separator for fuel cells by the horizontal electroforming process, process conditions, electrolyte composition, plating solution composition, etc. are not particularly limited, and the range and composition generally performed in the electroforming and plating processes. This can be done.

As described above, the method for manufacturing the Fe / Cr-CNT metal separator plate and the horizontal pole device by the pole method according to each embodiment of the present invention has been described, but such a method and device are limited to those embodiments. It will be understood by those skilled in the art that the present invention may be modified appropriately.

Hereinafter, the present invention will be described in detail with reference to Examples. The following examples are provided to aid the understanding of the present invention, and thus do not limit the present invention.

Example 1

STS 304 steel sheet stamped on both sides of the flow path of the general fuel cell metal separator plate of FIG. 2 as a mother plate through the mother plate supply device 10 and the conductor roll 31 of the horizontal pole device having the configuration as shown in FIG. It is supplied between the anode electrode 32 of the supply at a feed rate of 50mpm (meter per minute), and the electrolyte solution through the electrolyte nozzle 38 in the electrolyte flow path formed by the anode electrode 32 and the mother plate 11 of the pole cell Was fed in Reynolds number (Re) 1000. As the electrolyte solution, FeCl ₂ · 4H ₂ O 300g / l, and CaCl ₂ 335g / l, an aqueous solution of pH 0.5 ~ 1.5, temperature 89 ~ 90 ℃ was used. An electrolytic reaction was carried out at a current density of 5.6 A / dm 2 to form a Fe electrodeposition layer having a thickness of 50 μm on both sides of the mother plate. The formed Fe electrodeposition layer was separated to obtain a Fe thin film. The thin film thus obtained was sufficiently washed with water and then dried. The prepared Fe thin film is a pure iron thin film, the size of the nano-crystals was 10nm.

CrO ₃ 250g / l, H ₂ SO ₄ 2.5g / l and CNT 10g / l (mixed acid (1: 1 volume ratio) and PEI (polyethylene imide) solution sequentially on both surfaces of the obtained Fe thin film Immersed PEI-treated CNTs), and a Cr-CNT layer was formed at a current density of 10 A / dm 2 using an aqueous solution having a pH of 1 to 2 and a temperature of 55 ° C. as an electrophoretic solution. The Cr-CNT layer contains 20 wt% CNT, residual chromium and other unavoidable impurities. At this time, three kinds of Fe / Cr-CNT metal separator plates for fuel cells were prepared, such that the thickness of the Cr-CNT layer was 1 μm, 3 μm, and 20 μm, respectively.

The contact resistance and corrosion current of the manufactured Fe / Cr-CNTP metal separator plate and the SUS316L substrate for fuel cell were measured by the following method, and are shown in Table 1 below.

Contact resistance was measured by the Davies method (DP Davies, J. Power Sources 86 (2000) p.237) by applying a current of 5 A at a contact pressure of 50 ~ 150 N / ㎠ at room temperature.

Corrosion test is H ₂ SO ₄ Corrosion current data of SCE (Saturated Calomel Electrode) obtained by adding the prepared Fe / Cr-CNT metal separator specimen to the mixed test solution having a concentration of 0.001 N and 5 ppm of HF and applying a current of 0.6 V at 80 ° C. It was.

The fuel cell characteristics were ETEK's ELAT 0.5mg Pt / ㎠ carbon fiber paper and Fe / Cr-CNT metal separator prepared as electrode and Dupont's Nafion 112 as electrolyte membrane and the cell (cell) temperature 80 ℃, The stoichiometric ratio (volume ratio) of hydrogen / air was measured at 1.5 / 2.0, atmospheric pressure, and 1 A / cm 2, showing a sufficient operating voltage of 0.69 V in all three Fe / Cr-CNT metal separators.

Metal separator Contact resistance (mΩ㎠) Corrosion Current (mA / ㎠) Example 1
(Cr-CNT layer thickness 1㎛) 17.6 1.37 Example 1
(Cr-CNT layer thickness 3㎛) 15.3 1.16 Example 1
(Cr-CNT layer thickness 20㎛) 12.1 1.03 SUS316L 39 5.2

As shown in Table 1, the Cr-CNT layer thickness of 1㎛, 3㎛ and 20㎛ Fe / Cr-CNT metal separator prepared in Example 1 compared to the SUS316L substrate used as a conventional fuel cell metal separator Low contact resistance and corrosion current. It can be seen from the low contact resistance and corrosion current that the Fe / Cr-CNT metal separator is suitable for use in a fuel cell and exhibits excellent corrosion resistance compared to SUS316L.

10: Bedplate Feeder 11: Bedplate
12: bonding means 13: polishing means
14: pre-washing device 30: horizontal cell
31, 31 ': Conductor roll 32: anode electrode
33: current supply device 34: electrolyte reservoir
35: electrolyte heater 36: electrolyte filter
37: electrolyte pump 38: electrolyte nozzle
50: Fe / Cr-CNT thin film 51: thin film separator (peel roll)
52: post-cleaning device 54: metal separator cutting device
55: metal separator winding device 71: plate cutting device
72: base plate winding device 100: horizontal pole
P: electrophoresis device

Claims (9)

Fe / Cr-CNT metal separator plate for fuel cells comprising an iron thin film and a chromium and CNT-containing layer formed on both sides of the iron thin film, the flow path shape of the separator plate for the fuel cell.
The Fe / Cr-CNT metal separator for fuel cell according to claim 1, wherein the iron thin film has a thickness of 30 µm to 70 µm.
The Fe / Cr-CNT metal separator for fuel cells according to claim 1, wherein the iron thin film has a nano-sized grain structure.
The Fe / Cr-CNT metal separator for fuel cells according to claim 1, wherein the chromium and CNT-containing layers have a thickness of 0.1 µm to 20 µm.
The fuel cell Fe / Cr-CNT metal separator of claim 1, wherein the chromium and CNT-containing layer comprises 50 wt% to 90 wt% chromium and 10 wt% to 50 wt% CNT.
Supplying an electrolyte solution containing an iron precursor to a surface of a conductive mother plate having a flow path shape of a separator plate for a fuel cell horizontally supplied in a predetermined direction;
An electric current is applied to the anode plate and the cathode which are spaced apart from the surface of the mother plate where the flow path shape of the fuel cell separation plate is formed so that iron is electrodeposited on the surface of the conductive mother plate where the flow path shape of the fuel cell separation plate is formed. Making;
Separating the iron electrodeposition layer formed by electrodeposition; And
A method of manufacturing a Fe / Cr-CNT metal separator for a fuel cell, comprising forming chromium and CNT-containing layers on both sides of an iron thin film obtained by separation of the iron electrodeposition layer.
The method of claim 6, wherein the flow path of the separator for fuel cell is formed on one or both surfaces of the conductive mother plate.
The method of claim 6, wherein the iron precursor is at least one selected from the group consisting of iron sulfate, iron chloride, iron nitrate, and iron sulfamate.
The method of claim 6, wherein the forming of the chromium and the CNT-containing layer is performed by a cathodic electrophoresis method using a suspension containing a chromium precursor and a CNT.

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