KR101033204B1 - manufacturing technology and method to produce low-cost carbon composite plate whose surface is coated with metal nano particles - Google Patents

Abstract

The present invention improves the electrical conductivity, which is a disadvantage of composite plate made by mixing and compression molding Graphite powder and resin powder, and improves the weight and corrosiveness which is a disadvantage of metal separator. It is possible to provide a fuel cell separator capable of producing a fuel cell having excellent performance and durability by further plating any one of nickel alloy or gold such as nickel palladium for better performance.

The advantage of a fuel cell is that it is pollution-free equipment that generates only electricity, heat and pure water during operation. However, since H ion, which is a hydrogen ion component, is more than OH ion water, water having pH is acidic is generated, The performance of the fuel cell deteriorates due to the oxidation of the separator plate plating layer and the performance of the fuel cell deteriorates due to the corrosion of the base material of the metal separator plate for a long period of time due to the weak portion of the plating.

For this reason, a uniform plating layer is coated on a composite plate formed by mixing and compression molding of graphite powder and resin powder which have no corrosion, and nickel is electroless plated for excellent adhesion, and nickel alloy such as nickel palladium which is excellent in electrical property and corrosion resistance Gold can be prevented from being oxidized and the electrical properties and corrosion resistance can be improved. Thus, it is possible to provide an economical separator for a fuel cell which improves the performance and extends the lifetime of the fuel cell.

According to the present invention, a uniform plating layer is formed on a composite plate formed by mixing and compression molding of Graphite powder and a resin powder, and electroless plating of thin nickel is performed for excellent adhesion, and then either nickel alloy such as nickel palladium or gold It is possible to provide a separator having a reduced production cost and improved performance by further plating, thereby improving the performance of fuel cells for home use, fuel cells for notebook computers, and fuel cells for automobiles. In the separator era where the cutting process is performed, the thickness of the nickel plating is reduced in the separator for electroless plating of nickel in the composite plate having merits of the composite plate and the metal separator, and either nickel alloy such as nickel palladium or gold is added It is possible to mass-produce a separator capable of reducing the weight and thickness by plating and making the fuel cell performance excellent at a relatively low production cost.

Fuel Cell, Separator, Composite Plate, Electroless Nickel Plating.

Description

Low cost Carbon Composite Plate with metal nano particle surface treatment. {manufacturing technology and method to produce low-cost carbon composite plate whose surface is coated with metal nano particles}

1 is an overall process diagram for fabricating a separator for a low-cost carbon composite plate fuel cell in which metal nano particles are surface-treated.

<Major Numbers in Drawings>

S100: Powdering step S200: Partial kneading and further pulverization step

S300: full mixing step S400: disk forming step

S500: nickel plating step S600: nickel alloy or gold plating step

The present invention relates to a separator for a hydrogen and a hydrogen-containing fuel cell and a method for producing the separator. The separator is formed by mixing and compression molding Graphite powder, resin powder, etc., electroless nickel plating and adding either nickel alloy such as nickel palladium or gold The present invention provides a separator for a hydrogen and hydrogen compound fuel cell, which is low in cost and easy to mass-produce, which is capable of producing a fuel cell excellent in performance and durability by plating.

Hydrogen and Hydrogen Fuel Cells (hereinafter referred to as "fuel cells") can supply both electric energy and thermal energy by supplying hydrogen and oxygen in the air. Since they are not environmentally friendly except for pure water, they can be used for fossil fuel depletion such as petroleum and coal. Many studies are underway as a next-generation energy source attracting attention as international environmental regulations such as the Kyoto Protocol on Contrast and Climate Change Conventions are strengthened. In order for such a fuel cell to be widely used, the price of a solid polymer membrane, a platinum catalyst, a separator, etc., which constitutes a large part of the manufacturing cost of components constituting the fuel cell, must be lowered.

Japanese Patent Application Laid-Open No. 8-222241 proposes a method of manufacturing a graphite plate by mechanically machining it. However, when a grain (flow path) is mechanically drawn on the front and back surfaces of the graphite plate, There is a risk that the separator can not be made to have a thickness of 2.5 mm or less because of the risk of breakage, and thus the separator is heavy in weight and expensive, and JP-A-2001-335695 and Korean Patent Publication No. 2003-0030885 There is proposed a method in which a conductive carbon material and a thermosetting resin such as an epoxy resin are formed into powders by injection or compression molding. However, compared with a method of manufacturing a graphite plate by mechanical processing, a nonconductive By including the thermosetting resin as a material, the efficiency and durability of the separator are reduced. It had the disadvantage that. In order to overcome these disadvantages, Korea Patent No. 0533104 proposes to increase the performance of the separator by adding an antistatic agent to the mixture by injection or compression molding. However, since carbon black also acts as an antistatic agent, carbon black is actually added as an antistatic agent The performance of the separator can not be improved. Therefore, the problem that the performance of the separator manufactured by injection molding or compression molding is lower than that produced by mechanical processing is still not solved. In order to solve this problem, the present applicant's patent No. 0761645 has felt the need to improve the durability, power density, electrical resistance, and the like of the fuel cell by operating the actual fuel cell.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems,

After forming excellent powders into powders, the powders are manufactured by compression molding or injection molding, and nickel is electrolessly plated on the separator disk which is compression molded or injection molded. Then nickel alloy such as nickel palladium or gold A separator for a fuel cell, and a method of manufacturing the separator, which can form an excellent fuel cell having improved performance and durability by further plating any one of them.

The present invention relates to the production of a separator for a low-cost carbon composite plate fuel cell in which metal nanoparticles are surface-treated, and more particularly to a separator for a fuel cell, which comprises powdering a non-carbonaceous material such as graphite, epoxy resin, curing agent and curing accelerator, A separator for a fuel cell manufactured by processing the separator for a fuel cell, the separator for a fuel cell is used as an original plate, nickel is electrolessly plated on its surface, and nickel alloy such as nickel palladium or gold is further plated. At this time, the thickness of the plated nickel is preferably 0.1 占 퐉 or more and 10 占 퐉 or less, and the thickness of the nickel alloy or gold such as nickel palladium is preferably 1 nm or more and 10 占 퐉 or less.

On the other hand, the separator for a low-cost carbon composite plate fuel cell in which metal nanoparticles are surface-treated according to the present invention is characterized in that the graphite as the conductive carbon material is 60 wt% or more and 85 wt% or less and the non-carbonaceous material such as epoxy resin, Wherein the conductive carbon material is composed of 15 to 40% by weight of a separator for fuel cells having an average particle size of 30 to 50 m.

The separator disk for fuel cells may further comprise 0.5 to 1% by weight of carbon black based on 100% by weight of the graphite as the electrically conductive carbon material and the non-carbonaceous material, a mixed amount of graphite as the electrically conductive carbon material and the non-carbonaceous material 0.5 to 1.5% by weight, based on 100% by weight of a mixture of graphite, which is a conductive carbon material, and the non-carbonaceous material, 0.5 to 1% by weight of silicon dioxide (SiO ₂ ) And a reinforcing material composed of any one of bone powder or a mixture (shell-shell powder).

The separator for a low-cost carbon composite plate fuel cell in which metal nanoparticles are surface-treated according to the present invention will be described in detail. A separator for a fuel cell comprises a conductive carbon material such as natural graphite and artificial graphite, A thermosetting resin such as an epoxy resin or a phenol resin and a hardening accelerator, an aerosol, and a reinforcing material, which act to smooth the molding and fix the conductive carbon material, are manufactured as powder raw materials, Should be not less than 60 wt% and not more than 85 wt% of the weight of the material powder. If the proportion of the conductive carbon material is less than 60 wt%, the strength and durability of the separator are excellent, but the electrical conductivity is poor. When the proportion of the conductive carbon material exceeds 85 wt%, the electrical conductivity of the separator is excellent And the strength and durability of the separator itself become weak.

Graphite is the most preferable conductive carbon material used as a material for forming the separator disk, and acetylene black or the like is not suitable for use because it has a problem of hydrogen permeation because of a large pore. At this time, the conductive carbon material is used as a material made of powder. The size of graphite is most preferably 30 μm or more and 50 μm or less in average particle size because of electrical conductivity and hydrogen permeability. Graphite is artificial graphite and natural graphite, and any of them can be used.

On the other hand, since the original separator plate can not be produced by molding only graphite powder, the thermosetting resin is powdered and mixed with graphite to be molded. Considering that heat is generated with the electricity when the fuel cell is operated, the thermosetting resin having no deformation in the heat and having high hardness should be used for the molding process. Epoxy resin is mainly used. As the epoxy resin, bisphenol A type or novolac type is preferred, and the softening point is high, so that it is possible to prepare powder.

The curing agent is necessary for the curing of the epoxy resin which is added together at the time of producing the separator disk. These hardeners are preferably phenolic resins and have a high softening point so that they can be manufactured.

The curing accelerator is essential for mass production because it plays a role in increasing the production speed by shortening the minimum gell time for curing the product when manufacturing the fuel cell separator. As the hardening accelerator, organophosphorus is preferable and it is possible to prepare powder.

The carbon black should be 5 nm or less in size, and 1 to 2% by weight is used when the amount of graphite as the conductive carbon material and the non-carbonaceous material together with the aerosil is 100% by weight, It is the role of

Aerosil uses silicon dioxide (SiO ₂ ) powder with a size of 5 nm. When it is produced by suppressing permeation of hydrogen like carbon black and molding a separator for a fuel cell, the resin and the curing agent are thixotropic And is prevented from being separated from graphite due to high pressure and high temperature due to high temperature. The amount of the aerosol to be added is preferably 0.5 to 1% by weight based on 100% by weight of the graphite as the conductive carbon material and the non-carbonaceous material.

On the other hand, if necessary, a reinforcing material composed of at least one of animal bone and shells (shell shell powder) may be added to reinforce the bending strength of the separator disk, so that the separator disk can be formed and processed. Is preferably used in an amount of 0.5 to 1% by weight based on 100% by weight of the mixture of graphite, which is a conductive carbon material, and the non-carbonaceous material.

After the raw material of the separator is pulverized, the original plate is subjected to electroless plating and nickel is electroless plated on the original plate. The reason why electroless plating is performed using nickel as a raw material for the separator disk is to increase the electrical conductivity of the separator And the durability of the separator itself can be enhanced by the nickel plated on the surface. This is because the graphite, which is the main material of the separator disk, is not corrosive and therefore has better adherence than plated on a disk of a metallic material, and even if a plated part is damaged or damaged, there is no risk of corrosion around the periphery thereof. In addition, it can maintain a uniform plating thickness, and exhibits excellent adhesion even when nickel plating such as nickel palladium or gold is further plated for fuel cell performance improvement and excellent durability. If any one of nickel alloy or gold such as nickel palladium is directly plated on a separator formed by compression molding nickel without electroless plating, the adhesion is decreased and the thickness of the plating is also unstable, so that the performance of the fuel cell is deteriorated.

When nickel is plated on the separator disk, it is preferable that the separator is plated to a thickness of 0.1 탆 or more and 10 탆 or less. When the thickness of the plating is made thinner than 0.1 탆, there is a problem in improving the electrical conductivity of the separator. When the thickness of the plating is formed to exceed 10 탆, the improvement of the electrical conductivity and This is because the plating cost is increased irrelevantly and the economical efficiency is deteriorated.

In order to improve the electrical performance and durability of the fuel cell after electroless plating of nickel, plating thickness is preferably 1 nm or more and 10 μm or less even when nickel alloy or nickel such as nickel palladium is further plated. When the thickness is less than 1 nm, there is a problem in improving electrical properties and corrosion resistance, and when the thickness is more than 10 μm, the economical efficiency is likewise decreased.

Meanwhile, a method for manufacturing a separator for a low-cost carbon composite plate fuel cell in which metal nanoparticles are surface-treated, which is another aspect of the present invention, comprises the steps of powdering a non-carbonaceous material such as graphite, epoxy resin, curing agent and curing accelerator, (S100); (S200) of additionally pulverizing the graphite and the epoxy resin, which are conductive carbon materials, of the material that has undergone the pulverization step, and partially kneading the graphite and the curing agent as the conductive carbon material, respectively; Adding a hardening accelerator to the material having undergone the partial kneading and the additional pulverizing step, and mixing the hardening accelerator as a whole (S300); A step (S400) of forming a powdery material through the entire mixing step into a metal mold to form a separator disk for a fuel cell (S400), and a step S500 of electroless plating nickel on the molded separator disk for a fuel cell; And a step (S600) of further plating any one of a nickel alloy such as nickel palladium or gold.

Hereinafter, a separator for a low-cost carbon composite plate fuel cell in which metal nano particles are surface-treated using the present invention will be described in detail.

1 is an overall process diagram for fabricating a separator for a low-cost carbon composite plate fuel cell in which metal nano particles are surface-treated.

First, all of the separator disk forming materials composed of the graphite, the thermosetting resin, the curing agent, the curing accelerator, the aerosol, the carbon black, and the reinforcing agent described above must be pulverized into powder.

At this time, in order to impregnate the graphite into the non-carbon-based resin well, it is necessary to separately knead each of them partly. Therefore, graphite and an epoxy resin are blended in an amount of 10% by weight of graphite and 50% by weight of epoxy resin and kneaded. After that, graphite and a curing agent are mixed again with 25% by weight of graphite and 8% by weight of a curing agent, . This is because it is difficult to determine a certain molding temperature when the separator disk is molded due to the curing reaction unless it is partially kneaded, and there is a problem that the completed disk is not easily demoulded from the mold die, resulting in difficulty in production. After the partial kneading is completed, it is preferable that each of the pulverization processes is performed once more, or is further mixed with other powder materials, and thereafter is further subjected to another pulverization process.

After the partial kneading and the additional pulverization step, they are mixed together as a whole, and the powders are mixed well using an agitator. As the agitator, a Henschel mixer can be used.

After be a well kneading powdered molding materials such as the hydrogen or air is to make flow path into the separator mold for disc production designed to be integrally formed on the surface of the separator passes 700kg / cm ² ~ 1500kg / cm ² or less at a temperature of 180 ° C to 300 ° C for 1 to 3 minutes and then cooled, the original separator plate is completed.

Thereafter, nickel is uniformly plated on the outer surface of the separator disk using either electroless plating or electroplating on the separator disk.

The electroless plating is also called chemical plating or autocatalytic plating. When a reducing agent such as formaldehyde or hydrazine in an aqueous solution is used to reduce the metal ion to a metal molecule This reaction takes place at the catalyst surface. The most commonly used plating agents are copper, nickel-phosphorus and nickel-boron alloys. The use of such electroless plating allows the plating layer to be denser than electroplating and to maintain a specific thickness in the range of 0.1 to 10 mu m, and it is also advantageous in that plating can be performed on various substrates such as plastics and organics in addition to conductors .

Of course, in addition to the electroless plating described above, if necessary, nickel can be plated on the separator disk by electroplating. After nickel electroless plating is performed, a nickel alloy such as nickel palladium or gold is further plated to complete a separator for a low-cost carbon composite plate fuel cell in which metal nanoparticles of the present invention are surface-treated.

A separator for fuel cells that can reduce the thickness of nickel plating and nickel plating such as nickel palladium and thinly add gold to reduce the cost and improve the performance and durability of corrosion, contact resistance and electric power density. Can be manufactured.

Comparative Examples and Examples are described below to help understand the present invention.

When the compression molding or injection molding using the powder material according to the present invention is performed, the thickness of the separator for fuel cell can be made up to 0.8 mm. However, a jet mill, a Henschel mixer, a sophisticated compression molding press, The following comparative examples and examples were tested using a separator for a fuel cell having a width of 100 mm, a length of 100 mm, a thickness of 2 mm and a channel depth of 0.5 mm as a separator.

(Comparative Example 1)

Graphite 75% by weight Other powders 25% by weight were put into a ball mill and pulverized to have an average particle size of 30 탆. The powder was placed in a mold having a width of 100 mm, a length of 100 mm, a width of 2 mm and a channel depth of 0.5 mm, cm &lt; ² &gt; for 90 seconds to obtain a separator for a fuel cell having a flexural strength of 2500 psi, an electrical conductivity of 70 S / cm, and a thermal deformation temperature of 198 deg.

(Example 1)

Graphite 75% by weight Other powders 25% by weight were put into a ball mill and pulverized to have an average particle size of 30 탆. The powder was placed in a mold having a width of 100 mm, a length of 100 mm, a width of 2 mm and a channel depth of 0.5 mm, cm ² for 90 seconds at a temperature of 180 캜 for 90 seconds, and nickel was plated to a thickness of 15 탆 by a electroless plating method using a separator for a fuel cell as a base plate to obtain a bending strength of 2800 psi, an electric conductivity of 250 S / Nickel-plated separators for fuel cells.

(Comparative Example 2)

50% by weight of graphite and 10% by weight of epoxy resin were put into a ball mill and pulverized to have an average particle diameter of 30 μm. The resulting powder was put in a pressure kneader and subjected to a pressure of 5 kg / cm ² at 100 ° C. and kneaded for 80 minutes. Also it was crushed into an average particle diameter of the phenol resin 30㎛ 8% by weight of graphite as a 25% by weight and a curing agent and kneaded into this in the pressure kneader to give a pressure of 5kg / cm ² eseo 100 ℃ 80 minutes and allowed to cool. The above two powders were put together in a ball mill, and 5% by weight of a curing accelerator, 0.5% by weight of carbon black, 0.5% by weight of aerosol and 1% by weight of bone powder were mixed together and pulverized to an average particle size of 30 μm Respectively. The powder thus prepared was placed in a mold having a width of 100 mm, a length of 100 mm, a width of 2 mm and a depth of 0.5 mm and molded at 180 캜 under a pressure of 800 kg / cm ² for 90 seconds to provide a bending strength of 3500 psi, A separator for a fuel cell having a heat distortion temperature of 198 DEG C was produced.

(Example 2)

A nickel-plated nickel-plated nickel-plated battery having a flexural strength of 3800 psi, an electrical conductivity of 250 S / cm and a thermal deformation temperature of 198 ° C was prepared by electroless plating using a separator for fuel cell as in Comparative Example 2, I made a separator.

(Comparative Example 3)

A separator for a fuel cell was fabricated in the same manner as in Example 2, and the temperature was controlled to 60-90 ° C on the anode side and 55-85 ° C on the cathode side at 50-80 ° C on the cell side, The unit fuel cell performance test was carried out under the condition that the pressure on the hydrogen side and the oxygen side was maintained at 1 to 5 atmospheres to show an electrical resistance of 0.67 m? / Cm 2 under the conditions of Power Density of 0.42 W / cm 2, 140 N / And the corrosion current density of 6-11μA / ㎠ was exhibited under the condition of strong acidity (pH 1-3) generated during fuel cell operation.

(Example 3)

A nickel-palladium alloy was further plated to a unit fuel cell by making a separator for a fuel cell (nickel plating thickness is 5 mu m) as in Example 2, and a unit fuel cell performance test was conducted under the same conditions as in Comparative Example 3 A power density of 0.59 W / cm 2, an electrical resistance of 0.15 mΩ / cm 2, and a corrosion current density of 2-6 μA / cm 2 were produced, and a separator for a fuel cell (nickel plating thickness of 5 μm) Was subjected to a unit fuel cell performance test under the same condition as in Comparative Example 3 to obtain an electric resistance of 0.66 W / cm 2, 0.09 mΩ / cm 2, and a corrosion current density of 0.5-2 μA / cm 2 .

As shown in the results of these Examples, it is possible to make a separator capable of improving the performance and durability of a fuel cell by kneading graphite and resin, compression molding, and further nickel plating such as nickel palladium or nickel after electroless nickel However, the selection of either nickel alloy or gold, such as nickel palladium, should be determined through more experiments by comparison of performance and production cost. It is a big problem because I can not give many examples because of economic problems.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as set forth in the accompanying drawings. And modifications are within the scope of the appended claims.

As described above, after the graphite, the thermosetting resin, the graphite and the curing agent are respectively pulverized and kneaded, the whole is pulverized to form a separator for a fuel cell, and then a nickel plate is electrolessly plated with a disk and nickel alloy such as nickel palladium It is possible to provide a separator for a fuel cell capable of reducing the thickness, weight and production cost as well as improving the performance and durability of the fuel cell, compared with a separator for fuel cells manufactured through mechanical processing, that is, .

Claims (3)

A separator for a fuel cell produced by powdering a non-carbonaceous material such as graphite, a conductive carbon material, an epoxy resin, a curing agent and a curing accelerator, Wherein the formed metal nanoparticles are subjected to electroless plating with a thickness of not less than 0.1 m and not more than 10 m on the surface of the separator for fuel cell, Low cost carbon composite plate with particle surface treatment. delete delete

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