JP2006302529A - Manufacturing method of separator for solid polymer fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a separator for a solid polymer fuel cell, by which excellent corrosion resistance and conductivity are given to the separator, and manufacturing cost of the separator can be reduced. <P>SOLUTION: The manufacturing method of the separator comprises: a first step for forming corrosion resistance film 15 on a surface of a metal base 12 having an electrode contact surface 13 and a channel 14 for reaction gas passage; a second step for removing the corrosion resistance film 15 from the electrode contact surface 13 by polishing the corrosion resistance film 15 on the electrode contact surface 13; and a third step for forming a carbon film 16 by applying a mixture prepared by adding carbon to one of organic compounds that are a photoresist, polyacrylonitrile (PAN), polymethacrylic acid methyl (PMMA) and methyl methacrylate (MMA) to the electrode contact surface 13 and the surface of the channel 14 for the reaction gas passage after the first and second steps, and by calcinating the applied mixture at the temperatures of 500 to 550 °C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a separator incorporated in a cell of a polymer electrolyte fuel cell.

A polymer electrolyte fuel cell (hereinafter simply referred to as “fuel cell”) is a device that generates electricity by supplying a reaction gas (hydrogen / oxygen) to an electrode made of a polymer electrolyte membrane.
A fuel cell includes a membrane electrode assembly (MEA) having a structure in which an electrolyte membrane is sandwiched between a pair of gas diffusion electrodes constituting a positive electrode (cathode) and a negative electrode (anode), and separators disposed on both sides thereof Consists of. In the cell having the above configuration, only a voltage of less than 1 V can be obtained for each cell. Therefore, as an actual fuel cell, a cell in which several tens to several hundreds of cells are stacked in series is usually used.

Fuel cell separators are required to have various functions such as conductivity, corrosion resistance, and gas impermeability. In particular, a separator for an automotive fuel cell is required to have high mechanical strength and light weight in addition to the above functions.
As a base material for a separator of a fuel cell, conventionally, a resin such as graphite mixed with a binder resin and heated and compression molded or injection molded has been used. However, in order to develop a fuel cell having a smaller size and a higher output, if the separator is made thinner, the mechanical strength and workability are limited. Therefore, development of a separator based on a metal such as aluminum or stainless steel, which is excellent in mechanical strength and formability even when the separator is thin, is now underway.

However, when a metal-based separator is used, there is a problem that the metal is corroded by protons in the fuel cell.
In addition, since a passive layer is formed on the metal surface, the contact resistance is higher than that of the carbon material, and when such a metal separator is energized, the voltage drop increases, leading to a decrease in fuel cell performance. There is a fear.

To solve the above problem, for example, after forming a dense anodized film and a porous anodized film on the surface of the aluminum metal plate and lapping and polishing the electrode contact surface of the aluminum metal plate, the electrode contact surface is removed. Patent Document 1 discloses a fuel cell separator having a conductive film made of noble metal or carbon.
Also, a fuel cell separator in which a porous anodic oxide film is formed on the surface of an aluminum alloy substrate, and a base metal layer made of Ni, Sn, etc. and a main metal layer made of Au or a platinum group metal are laminated on the film. Is disclosed in Patent Document 2.

Japanese Patent No. 3404363 JP 2003-123782 A

However, in the separator of Patent Document 1, since the anodized film has a two-layer structure of a dense anodized film and a porous anodized film, the film becomes thick and the corrosion resistance is improved, but the electrical resistance is increased, This causes a decrease in conductivity. In addition, when the conductive film is a noble metal film formed by sputtering, there is a problem that the manufacturing cost is high. When the conductive film is a carbon film formed by CVD, the carbon particles are in micron units. For this reason, pinholes are likely to be generated, and as a result, the separator is corroded and sufficient corrosion resistance cannot be obtained.
In the separator of Patent Document 2, when the base metal layer made of Ni, Sn or the like is laminated thickly and the main metal layer made of noble metal is formed thin, the durability is inferior, and the separator corrodes due to the generation of pinholes, There is a problem that sufficient corrosion resistance cannot be obtained. In order to ensure corrosion resistance and conductivity, it is necessary to form the main metal layer thick, but since the amount of noble metal used increases, the manufacturing cost increases.

  The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for producing a separator for a polymer electrolyte fuel cell, which can impart excellent corrosion resistance and conductivity to the separator and can reduce production costs. .

The first aspect of the present invention is a method for producing a separator for a polymer electrolyte fuel cell comprising a metal base material and comprising an electrode contact surface and a reaction gas channel groove,
A first step of forming a corrosion-resistant film on the surface of the metal substrate; a second step of polishing the corrosion-resistant film on the electrode contact surface to remove the corrosion-resistant film from the electrode contact surface; Carbon is added to any organic compound of acrylonitrile (PAN), polymethyl methacrylate (PMMA), or methyl methacrylate (MMA) to prepare a mixture of the organic compound and carbon, and the first and second steps are performed. It comprises a third step of forming a carbon film by applying the mixture to the electrode contact surface and the groove surface for the reaction gas flow path, and firing at a firing temperature of 500 ° C. or higher and 550 ° C. or lower. , Manufacturing method of separator for polymer electrolyte fuel cell and secondly,
A method for producing a separator for a polymer electrolyte fuel cell comprising a metal substrate and comprising an electrode contact surface and a reaction gas flow channel,
A first step of forming a corrosion-resistant film on the surface of the metal substrate; a second step of polishing the corrosion-resistant film on the electrode contact surface to remove the corrosion-resistant film from the electrode contact surface; and the corrosion-resistant film A third step of forming a film on the removed electrode contact surface by reduction reaction of diazotized nitrobenzene or electrolytic polymerization reaction of pyrrole, photoresist, polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), methacrylic acid Carbon is added to one of the organic compounds of methyl (MMA) to prepare a mixture of the organic compound and carbon, and the electrode contact surface and the reaction gas channel groove that have undergone the first, second, and third steps. The fourth step is to form a carbon film by applying the mixture on the surface and firing at a firing temperature of 500 ° C. or more and 550 ° C. or less. Characterized by comprising, to solve the above problems by a manufacturing method of a separator for a polymer electrolyte fuel cell.

  According to the first and second methods for producing a polymer electrolyte fuel cell separator of the present invention, the electrode contact surface is made conductive by applying different surface treatments to the electrode contact surface and the reaction gas flow channel groove. It is possible to improve the corrosion resistance on the surface of the reaction gas channel groove. In addition, after applying different surface treatments to the electrode contact surface and the reaction gas flow channel groove, the entire surface is covered with a smooth carbon film at the atomic level, thus preventing pinholes and preventing corrosion of the separator. In addition, the contact resistance with the electrode can be reduced.

  Hereinafter, the manufacturing method of the 1st separator for polymer electrolyte fuel cells of this invention is demonstrated in detail based on figures. FIG. 1 is a partial schematic view showing an example of a fuel cell centering on a separator produced by the first method for producing a polymer electrolyte fuel cell separator of the present invention. The polymer electrolyte fuel cell 30 includes a separator 10 made of a metal substrate 12, and a membrane electrode assembly (MEA) 20 made of a solid polymer electrolyte membrane (not shown) and a gas diffusion electrode (not shown). Become. The separator 10 includes a contact surface 13 with a gas diffusion electrode (hereinafter simply referred to as an “electrode”), an anode gas flow channel groove 14 a that is a flow channel for a reactive gas, that is, an anode gas and a cathode gas, and a cathode gas. A channel groove 14b is provided. As shown in FIG. 1, the anode gas channel groove 14a and the cathode gas channel groove 14b are formed in parallel on the front and back of the separator, but they may be formed orthogonal to each other on the front and back of the separator. Good. The groove depth is preferably 0.1 mm to 2.0 mm. Hereinafter, the anode gas flow channel groove 14 a and the cathode gas flow channel groove 14 b are collectively referred to as a reaction gas flow channel groove 14.

Examples of the metal substrate 12 of the separator 10 that can be used in the present invention include aluminum, stainless steel, titanium, nickel, and the like. Aluminum is preferably used from the viewpoint of excellent thermal conductivity and light weight. . As aluminum used in the present invention, in addition to pure aluminum having a purity of 99.0% or more, 2000 series Al-Cu alloy and Al-Cu-Si alloy, 3000 series Al-Mn alloy, 4000 series Al-Si Alloys such as 5000 series Al-Mg alloys, 6000 series Al-Mg-Si alloys, and 7000 series Al-Zn-Mg alloys.
The thickness of the metal substrate 12 is not particularly limited, but a thickness of 0.1 mm to 3 mm is preferable in order to satisfy the conditions of mechanical strength and gas impermeability.

As shown in FIG. 1, different surface treatments are performed on the electrode contact surface 13 and the surface of the reactive gas flow channel groove 14. That is, the electrode contact surface 13 is subjected to highly conductive surface processing, and the surface of the reaction gas flow channel groove 14 that does not contact the electrode is subjected to surface processing with high corrosion resistance.
The surface treatment procedure for the separator 10 includes the first step of forming the corrosion-resistant film 15 on the surface of the metal substrate 12 and the corrosion-resistant film 15 on the electrode contact surface 13 is polished to remove the corrosion-resistant film 15 from the electrode contact surface 13. And a third step of forming a carbon film 16 on the surface of the electrode contact surface 13 and the reactive gas flow channel groove 14 that have undergone the first and second steps. Hereinafter, each step will be described.

In the first step, the corrosion-resistant film 15 is formed on the surface of the metal substrate 12. The corrosion-resistant film 15 is preferably an oxide film of the metal base 12, and examples thereof include anodized when the metal base 12 is an aluminum alloy and chromium oxide when the metal base 12 is stainless steel.
When an aluminum alloy is used as the metal substrate 12, an alumite film is formed on the surface of the substrate by anodizing the aluminum alloy in an electrolyte such as sulfuric acid, oxalic acid, phosphoric acid, or chromic acid. After the anodizing treatment, the pores of the alumite can be closed by treatment with high-temperature pressurized steam or boiling in boiling water, and the corrosion resistance of the alumite film is improved.
The corrosion-resistant film 15 can obtain the same effect by modifying a fluororesin layer or an organic substance in addition to the oxide film. The film thickness of the corrosion resistant film 15 is preferably about 0.1 μm to 10 μm.

In the second step, the corrosion resistant film on the electrode contact surface 13 out of the corrosion resistant film 15 covering the substrate surface in the first step is polished to remove the corrosion resistant film 15 from the electrode contact surface 13. By removing the corrosion-resistant film, the conductivity of the electrode contact surface 13 can be improved. Further, since the surface is activated by removing the corrosion-resistant film, carbon and metal atoms of the carbon film 16 are bonded, and adhesion with the carbon film is improved.
Examples of the method for polishing the corrosion-resistant film 15 on the electrode contact surface 13 include chemical polishing, mechanical polishing, and blast polishing.

  In the third step, a carbon film 16 is formed on the electrode contact surface 13 and the surface of the reactive gas flow channel groove 14 that have undergone the first and second steps. The carbon film 16 is formed to impart corrosion resistance to the electrode contact surface 13 and to further improve the corrosion resistance of the reaction gas flow channel groove 14 covered with the corrosion resistant film 15. The carbon film 16 is a mixture of an organic compound and carbon obtained by adding carbon to any organic compound of photoresist, polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and methyl methacrylate (MMA). Is applied to the electrode contact surface 13 and the surface of the reaction gas channel groove 14 and fired.

Photoresist, which is one of the starting materials for the carbon film 16, is a photosensitive resin material that forms a corrosion-resistant film by utilizing the change in solubility due to photoreaction, and is an electronic material that precisely processes substrates such as metals and semiconductors by etching. Widely used in the field of printing materials.
It has been described in the literature that photoresist can be heat treated at 1000 ° C. resulting in low resistivity carbon. (Photoresist-derived Carbon for Microelectro-
See mechanical Systems and Electrochemical Applications, Srikanth Ranganathan et al, Journal of The Electrochemical Society, 147 (1) 277-282, 2000. )
The photoresist used in the present invention is preferably an alkyldiazo-based positive photoresist in which the photosensitive resin is an alkyldiazo compound and the binder resin is a novolac resin, but a diazonaphthoquinone (DNQ) -novolak resin-based positive photoresist, Naphthoquinonediazide-based positive photoresists, cyclized polyisoprene-azide compound-based resists, polystyrene-based negative photoresists, and the like can be used, and similar effects can be obtained.

When a photoresist is used as a starting material for the separator film, if the baking temperature is high, defects in the shape of the separator occur, such as warping or deformation of the aluminum substrate during baking.
When the photoresist is baked at a low temperature of about 500 ° C., the carbonization proceeds, so that corrosion resistance is ensured. However, since the resist has a high resistance value, sufficient conductivity cannot be ensured. However, when photoresist is added with carbon in a reducing atmosphere (97% Ar + 3% H2 or 93% Ar + 7% H2) and baked at a low temperature, corrosion resistance is maintained and sufficient conductivity is ensured. Was found by the present inventors.

As carbon added to any organic compound of photoresist, polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), methyl methacrylate (MMA), artificial graphite, natural graphite, ketjen black, activated carbon, Mesocarbon microbeads (MCMB), boron-modified acetylene black (BMAB), etc. can be used. These carbons are used alone or in combination of two or more.
The particle diameter of carbon is preferably in the range of 0.1 μm to 100 μm from the viewpoint of ensuring conductivity. Moreover, any of spherical shape, fibrous shape, and irregular shape can be used for the shape of the carbon particles.

The added amount of artificial graphite, natural graphite, activated carbon, and mesocarbon microbeads is 1 wt% or more and 30 wt% or less with respect to the photoresist.
The amount of ketjen black added is 1% by weight or more and 2% by weight or less based on the photoresist.
The amount of boron-modified acetylene black added is 1% by weight or more and 10% by weight or less based on the photoresist.
When the added amount of each carbon exceeds the range shown above, coating becomes difficult, and after firing, the carbon film 17 is peeled off from the non-conductive layer 15 and the conductive layer 16 and the corrosion resistance cannot be ensured.
Moreover, when the added amount of each carbon is less than 1% by weight, conductivity cannot be ensured.

Examples of the method for applying the mixture of the organic compound and the carbon include a spin coating method, a dip coating (dipping method), a blade coating method, and a spray coating method, and the spin coating method is preferable.
The firing temperature is 500 ° C. or higher and 550 ° C. or lower. By heat-treating the organic compound, the organic compound is changed to carbon, and a carbon film 16 is formed on the electrode contact surface 13 and the reaction gas channel groove 14 that have undergone steps 1 and 2.
When the firing temperature exceeds 550 ° C., as described above, there is a problem in the shape of the separator 10 such as warping or deformation of the aluminum base material during firing. On the other hand, when the firing temperature is less than 500 ° C., no improvement in conductivity is observed.
A film thickness of the carbon film 17 of about 1 μm to 50 μm is sufficient to ensure corrosion resistance and conductivity.

  In FIG. 1, the carbon film 16 is formed on the entire metal base 12, but the carbon film 16 may be formed only on one side of the metal base 12 depending on the shape and type of the separator.

Next, the manufacturing method of the 2nd polymer electrolyte fuel cell separator of this invention is demonstrated. In addition, about the structure same as the 1st polymer electrolyte fuel cell separator of this invention, the same code | symbol is used and description is abbreviate | omitted.
The separator 11 has a first step of forming a corrosion-resistant film 15 on the surface of the metal substrate 12 and a second step of polishing the corrosion-resistant film 15 on the electrode contact surface 13 and removing the corrosion-resistant film 15 from the electrode contact surface 13. And a third step of forming a film on the electrode contact surface 13 from which the corrosion-resistant film 15 has been removed by a reduction reaction of diazotized nitrobenzene or an electrolytic polymerization reaction of pyrrole, and the first, second, and third steps. This is a fourth step of forming the carbon film 16 on the electrode contact surface 13 and the surface of the reactive gas flow channel groove 14.

Steps 1 and 2 are performed in the same manner as in the first method for producing a polymer electrolyte fuel cell separator.
In the third step, after the corrosion-resistant film 15 on the electrode contact surface 13 is removed, a reduction reaction of diazotized nitrobenzene or an electropolymerization reaction of pyrrole is caused by cyclic voltammogram (CV), thereby forming a film on the electrode contact surface 13. 17 is formed.

For example, when an aluminum alloy is used as the metal substrate 12, carbon and aluminum atoms are bonded by the reduction reaction of diazotized nitrobenzene, and adhesion with the substrate is ensured. Since the film 17 produced by the reduction reaction retains the bonds between aluminum atoms and carbon even after firing, the corrosion resistance and conductivity of the electrode contact surface 13 can be improved.
In addition, when pyrrole is electropolymerized, a film 17 of pyrrole polymer is formed on the electrode contact surface 13, and organic substances enter inside the pores in the aluminum alloy, thereby ensuring adhesion with the substrate. . Moreover, since an aluminum atom and a carbon atom couple | bond together after baking, the corrosion resistance and electroconductivity of the electrode contact surface 13 can be improved.
In the fourth step, the carbon film 16 is formed on the electrode contact surface 13 and the surface of the reactive gas flow channel groove 14 that have undergone the first, second, and third steps. The method for forming the carbon film is the same as Step 3 in the first method for producing a polymer electrolyte fuel cell separator.

  Hereinafter, the present invention will be described specifically by way of examples. However, the present invention is not limited to these examples.

Example 1
As the metal substrate, an aluminum alloy (A5052P) having a length of 30 mm × width of 30 mm × thickness of 0.5 mm was used.
After polishing the natural oxide film on the substrate surface with a slurry of silicon carbide and octadecane in air to remove the natural oxide film, the substrate surface was ultrasonically cleaned using an organic solvent.
30% by weight of artificial graphite having an average particle size of 10 μm was added to polyacrylonitrile (PAN) and uniformly mixed with ultrasonic waves to prepare a coating solution.
This was dropped on the substrate surface, and a film was formed on both surfaces of the substrate with a spin coater (rotational speed 1000 to 2000 rpm). After drying at a drying temperature of 100 ° C. for about 2 hours to solidify the film, the film was baked in an argon-hydrogen mixed gas at 550 ° C. for 4 hours to form a carbon film on the substrate surface.

(Example 2)
In Example 1, polyacrylonitrile (PAN) is replaced with a photoresist (product number: OFPR5000 50CP) manufactured by Tokyo Ohka Kogyo Co., Ltd., and the amount of artificial graphite is changed to 1% by weight. Otherwise, the same as in Example 1 Thus, a carbon film was formed on the substrate surface.

(Example 3)
In Example 1, the substrate surface was polished in an inert atmosphere, and a carbon film was formed on the substrate surface in the same manner as in Example 1 except that.

Example 4
In Example 2, the substrate surface was polished in an inert atmosphere, and a carbon film was formed on the substrate surface in the same manner as in Example 2 except that.

(Example 5)
In Example 3, polyacrylonitrile (PAN) was replaced with polymethyl methacrylate (PMMA), and a carbon film was formed on the substrate surface in the same manner as in Example 3 except that.

(Example 6)
In Example 4, artificial graphite was replaced with ketjen black having an average particle size of 34.0 nm, and a carbon film was formed on the substrate surface in the same manner as in Example 4 except that.

(Example 7)
As the metal substrate, an aluminum alloy (A5052P) having a length of 30 mm × width of 30 mm × thickness of 0.5 mm was used.
After polishing the natural oxide film on the substrate surface with a slurry of silicon carbide and octadecane in an inert atmosphere, removing the natural oxide film, the reference electrode in the electrolyte solution of diazotized nitrobenzene, acetonitrile, tetrabutylammonium fluoroborate A silver electrode was used for the electrode and platinum was used for the counter electrode, and the diazotized nitrobenzene was reduced by cyclic voltammogram (CV) to form films on both sides of the substrate. Thereafter, ultrasonic cleaning of the substrate surface was performed using an organic solvent.
A coating solution was prepared by adding 1% by weight of artificial graphite having an average particle diameter of 10 μm to a photoresist (product number: OFPR5000 50CP) manufactured by Tokyo Ohka Kogyo Co., Ltd. and uniformly mixing with ultrasonic waves.
This was dropped on the substrate surface, and a film was formed on both surfaces of the substrate with a spin coater (rotational speed 1000 to 2000 rpm). After drying at a drying temperature of 100 ° C. for about 2 hours to solidify the film, the film was baked in an argon-hydrogen mixed gas at 550 ° C. for 4 hours to form a carbon film on the substrate surface.

(Example 8)
The same aluminum alloy as in Example 7 was used, and the natural oxide film on the substrate surface was polished with a slurry of silicon carbide and octadecane in an inert atmosphere. After removing the natural oxide film, cyclic voltammogram (CV) in acetonitrile was used. ), The pyrrole derivative was subjected to electrolytic polymerization to form a polymer of the pyrrole derivative, and a film was formed on both surfaces of the substrate. Thereafter, ultrasonic cleaning of the substrate surface was performed using an organic solvent. Thereafter, a carbon film was formed on the substrate surface under the same conditions as in Example 7.

(Comparative Example 1)
The same substrate as in Example 1 was naturally oxidized in air. The natural oxide film on the substrate surface was not removed, and no carbon film was formed.
Table 1 summarizes the carbon film starting materials of Examples 1 to 8 and Comparative Example 1, the type and amount of carbon added, and the surface treatment method of the substrate.

(Corrosion resistance evaluation: ICP measurement)
The corrosion resistance was evaluated for the above-described examples and comparative examples.
The substrate was immersed in an 80 ° C. aqueous solution in which 2 ppm of fluorine ions were added to sulfuric acid at pH 2, and the aluminum concentration in the aqueous solution was measured by ICP measurement. The measurement results are shown in FIG.

From FIG. 2, it can be seen that the aluminum concentrations of Examples 1 to 8 increase from 0 hours to about 400 hours, but hardly increase thereafter. This is probably because the carbon films formed on the base materials of Examples 1 to 8 are dense, so that the generation of pinholes is suppressed and the amount of eluted ions is reduced.
The aluminum concentration of Comparative Example 1 shows a relatively low value in the initial stage because the natural oxide film (aluminum oxide film) on the substrate surface has corrosion resistance. However, after the aluminum oxide film has been destroyed after 800 hours, the amount of ions eluted is considered to increase at an accelerated rate and the corrosion proceeds rapidly.

(Example 9: Trial manufacture of separator)
A reaction gas channel groove having a depth of 0.3 mm and a width of 2.0 mm was formed in an aluminum alloy (A5052P) having a length of 10 cm, a width of 10 cm, and a thickness of 0.5 mm to prepare a substrate.
The substrate was immersed in an aqueous sodium hydroxide solution for 10 minutes and then washed with water, and then immersed in an aqueous nitric acid solution for 10 minutes and then washed with water. Thereafter, anodization was performed in an oxalic acid electrolyte for 30 minutes to form an alumite film (corrosion resistance film) having a thickness of 4 μm on the surface of the substrate. After boiling for 30 minutes in ultrapure water and sealing, the alumite film on the substrate surface is polished with a slurry of silicon carbide and octadecane in an inert atmosphere to remove the alumite film on the electrode contact surface, and the organic solvent is removed. The substrate surface was subjected to ultrasonic cleaning.
A coating solution was prepared by adding 1 wt% of natural graphite having an average particle size of 10 μm to a photoresist (product number: OFPR5000 50CP) manufactured by Tokyo Ohka Kogyo Co., Ltd. and uniformly mixing with ultrasonic waves.
This was dropped on the substrate surface, and a film was formed on both surfaces of the substrate with a spin coater (rotational speed 1000 to 2000 rpm). After drying at a drying temperature of 100 ° C. for about 2 hours to solidify the film, the film was baked in an argon-hydrogen mixed gas at 550 ° C. for 4 hours to form a carbon film on the substrate surface, thereby producing a separator.

(Evaluation of corrosion resistance of separator)
A cell (electrolyzer) for a corrosion resistance test was prepared, and polarization measurement was performed.
Corrosion current was measured by immersing the substrate in an 80 ° C. aqueous solution in which 2 ppm of fluorine ions were added to pH 2 sulfuric acid, using a carbon electrode as a counter electrode and an Ag / AgCl electrode as a reference electrode. The corrosion curve was scanned in a range of ± 0.2 V from the open circuit potential, and the scanning speed was 1 mV / sec. The corrosion current density after 40 days from immersion was 0.3 μA / cm ² .

(Evaluation of conductivity of separator)
The separator was sandwiched between silver plate electrodes from both sides, and a load of 10 kgN was applied, and measurement was performed by the 4-terminal method. The contact resistance was 4.18 × 10 ⁻³ Ωcm ² .

  From the corrosion resistance / conductivity evaluation of the separator described above, the electrode contact surface is subjected to high conductivity surface treatment, the reaction gas flow channel groove is subjected to high corrosion resistance surface treatment, and the atomic contact surface is made of a smooth carbon film. It can be seen that coating the reaction gas channel groove can prevent corrosion of the substrate and reduce the contact resistance.

The fragmentary schematic diagram of the fuel cell centering on the separator for polymer electrolyte fuel cells of this invention. The graph which shows the ICP measurement result of an Example and a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,11: Separator for polymer electrolyte fuel cells 12: Metal base material 13: Electrode contact surface 14: Groove for reaction gas flow path 15: Corrosion-resistant film 16: Carbon film 17: Film 20: Electrode (membrane electrode assembly)
30: Polymer electrolyte fuel cell

Claims (5)

A method for producing a separator for a polymer electrolyte fuel cell comprising a metal substrate and comprising an electrode contact surface and a reaction gas flow channel,
A first step of forming a corrosion-resistant film on the surface of the metal substrate;
A second step of polishing the corrosion-resistant film on the electrode contact surface to remove the corrosion-resistant film from the electrode contact surface;
Carbon is added to an organic compound of any one of photoresist, polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and methyl methacrylate (MMA) to prepare a mixture of the organic compound and carbon. It comprises a third step of forming a carbon film by applying the mixture to the electrode contact surface and the groove surface for the reaction gas flow path that have undergone step 2 and firing at a firing temperature of 500 ° C. or higher and 550 ° C. or lower. Characterized by the
A method for producing a polymer electrolyte fuel cell separator. A method for producing a separator for a polymer electrolyte fuel cell comprising a metal substrate and comprising an electrode contact surface and a reaction gas flow channel,
A first step of forming a corrosion-resistant film on the surface of the metal substrate;
A second step of polishing the corrosion-resistant film on the electrode contact surface to remove the corrosion-resistant film from the electrode contact surface;
A third step of forming a film on the electrode contact surface from which the corrosion-resistant film has been removed by a reduction reaction of diazotized nitrobenzene or an electrolytic polymerization reaction of pyrrole;
Carbon is added to any organic compound of photoresist, polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), or methyl methacrylate (MMA) to prepare a mixture of the organic compound and carbon. 2. A fourth step of forming a carbon film by applying the mixture to the electrode contact surface and the reaction gas channel groove surface that have undergone the third step and firing at a firing temperature of 500 ° C. or higher and 550 ° C. or lower. It is characterized by consisting of
A method for producing a polymer electrolyte fuel cell separator.   The method for producing a separator for a polymer electrolyte fuel cell according to claim 1 or 2, wherein the corrosion-resistant film is an oxide film of the metal substrate or a film made of a fluororesin.   4. The method for producing a solid polymer fuel cell separator according to claim 1, wherein the photoresist is an alkyldiazo-based positive photoresist. The carbon is a mixture of one or more of artificial graphite, natural graphite, ketjen black, activated carbon, mesocarbon microbeads (MCMB), and boron-modified acetylene black (BMAB). 4. The method for producing a separator for a polymer electrolyte fuel cell according to any one of 4 above.

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