JP2007134107A - Separator for fuel cell, its manufacturing method and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell separator of a type which maintains corrosion resistance by its substrate and secures contact resistance by a carbon system membrane (C membrane), in which deterioration of contact resistance is suppressed as much as possible and hydrophilicity of the surface is carried out. <P>SOLUTION: This is the fuel cell separator in which a carbon based membrane (C membrane) in which one kind or more of metal oxides selected from an oxide of element of Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W is made a complex and contained in the separator substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell separator and a method for manufacturing the same, and further relates to a fuel cell including the separator.

In a polymer electrolyte fuel cell, a fuel gas containing hydrogen and an oxidizing gas containing oxygen are respectively supplied to two electrodes (an oxygen electrode and a fuel electrode) facing each other with an electrolyte membrane interposed therebetween. The cathodic reaction shown in (1) and the anodic reaction shown in the following formula (2) are performed, and chemical energy is directly converted into electric energy.
Cathode reaction (oxygen electrode): 2H + + 2e ⁻ + (1/2) O ₂ → H ₂ O (1)
Anode reaction (fuel electrode): H ₂ → 2H ⁺ + 2e ⁻ (2)
In order to perform the reaction of the formula (1) continuously and smoothly, it is necessary to quickly remove water generated at the oxygen electrode and continuously supply the oxidizing gas to the oxygen electrode. Usually, the supply channel for the oxidizing gas to the oxygen electrode is formed by a rib formed on the collector electrode on the oxygen electrode side and the surface of the oxygen electrode, and this supply channel also has a discharge channel for the generated water. Also serves as. Therefore, prompt discharge of the generated water in the oxidizing gas supply channel is required.

  In addition, in order to perform the reaction of the formula (2) continuously and smoothly, it is necessary to continuously supply the fuel gas to the fuel electrode and to smoothly diffuse the hydrogen ions generated at the fuel electrode into the electrolyte membrane. is there. Since hydrogen ions combine with water in the electrolyte membrane and move through the electrolyte membrane in a hydrated state, the electrolyte membrane must be replenished with water from the outside so as not to run out of water near the fuel electrode. Such replenishment of water to the fuel electrode is performed by humidifying the fuel gas and increasing the water vapor pressure. When such fuel gas is supplied to a fuel cell that has not reached the temperature during steady operation immediately after the start of operation, or when fuel gas with water vapor supersaturated is supplied to the fuel cell, In some cases, water vapor condenses on the formation surface of the fuel gas supply flow path formed by the rib formed on the collector electrode and the surface of the fuel electrode, thereby obstructing the smooth flow of the fuel gas. Therefore, it is required to quickly discharge water condensed on the formation surface of the fuel gas supply channel.

  Conventionally, as a fuel cell that meets such demands, a fuel cell in which a coating film of a fluororesin is formed on the surface of the supply flow path of the fuel gas or the oxidizing gas formed by the collector electrode and the electrode has been proposed. In these fuel cells, a supply path is formed by forming a fluororesin coating on the formation surface of the fuel gas or oxidant gas supply passage and making the formation surface of the fuel gas or oxidant gas supply passage water-repellent. The drainage from the water supply flow path generated inside is enhanced.

  In addition, a fuel cell in which a fluororesin coating is formed on the outlet end face of the supply channel has been proposed in order to enhance the discharge of water generated in the supply channel of the fuel gas or the oxidizing gas. In this fuel cell, water drainage in the vicinity of the outlet of the supply channel is improved by forming a fluororesin coating on the outlet end surface of the supply channel to make it water repellent.

  However, in such a fuel cell in which a coating film of fluororesin is formed on the surface where the supply channel is formed, if the width or depth of the fuel gas or oxidant gas supply channel is reduced, water generated in the supply channel causes a part of the supply channel. There is a problem that the operation efficiency of the fuel cell is lowered by blocking the flow of the fuel gas or the oxidizing gas.

Accordingly, it has been considered to improve the drainage by making the surface of the separator of the fuel cell hydrophilic. In general, as a method for improving the hydrophilicity, a method for improving the hydrophilicity of the film itself (for example, Patent Document 1 below) such as addition of a hydrophilic material system, and a hydrophilic material coating (TiO _2). Etc.) and a method of imparting a functional group by surface treatment such as plasma treatment (for example, Patent Document 2 and Patent Document 3 below).

  As a next-generation metal separator for fuel cells, it is under consideration to provide corrosion resistance with an Fe-based or Ti-based substrate and to ensure contact resistance with an inexpensive surface treatment. For example, SUS316L is used as a base material, and the surface thereof is Au treated with 10 nm as a low resistance film and C coating as a high corrosion resistance film to give conductivity and corrosion resistance, but it is expensive. . As a low-cost low-resistance treatment that can replace expensive noble metals, there is a C film, and low resistance can be secured by examining conditions. The remaining problem is improving the hydrophilicity of the C film for improving the drainage in the battery.

In the case of a method for improving the hydrophilicity of the film itself by adding a hydrophilic element (B, N, etc.), although the hydrophilicity is improved by the added element, insulating ceramics (shelfed products, nitrides) are formed in the film. There is a problem that conductivity is deteriorated. In addition, in the functional group imparting method by applying a hydrophilic material such as TiO ₂ or surface treatment such as plasma treatment, the hydrophilicity is improved by imparting the hydrophilic group to the surface, but the OH group having low conductivity and having polarity is low. There is a problem that the contact resistance increases by being formed on the film surface.

  On the other hand, in Patent Document 4 below, a separator for a polymer solid electrolyte fuel cell having a small contact electric resistance with an anode and a cathode and excellent in corrosion resistance is mainly composed of hydrogen and carbon on the surface of the separator. An invention is disclosed in which a layer made of diamond-like carbon is included, and the layer made of diamond-like carbon contains a dopant other than hydrogen and carbon.

Special table 2003-534223 gazette JP-A-11-110743 JP 2005-146060 A JP-A-2005-93172

  In the fuel cell separator of the present invention, in which corrosion resistance is provided by a base material and contact resistance is ensured by a carbon-based membrane (C film), the surface is made hydrophilic while suppressing deterioration of the contact resistance as much as possible. The purpose is to do.

  The present inventors have found that the above problem can be solved by forming a carbon-based film (C film) in which a specific compound is compounded on a separator substrate, and have reached the present invention.

  That is, first, the present invention is an invention of a separator for a fuel cell, and is selected from oxides of elements of Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W on the separator substrate. A carbon-based film (C film) containing a composite of one or more metal oxides is formed. These metal elements have a relatively high ability to form oxides, and are easily oxidized to form metal oxide fine particles by a method as described later, and are combined into a carbon-based film (C film). While the carbon-based film (C film) itself is hydrophobic, the composite metal oxide fine particles have hydrophilicity and help drain excess water near the separator.

  The fuel cell separator of the present invention is sufficiently hydrophilized by a carbon-based film (C film) formed on the surface and containing a composite of metal oxide. Specifically, the contact angle on the surface of the carbon-based film (C film) is preferably 75 ° or less.

At the same time, the contact resistance is suppressed by the carbon-based film (C film) that is formed on the surface of the separator for a fuel cell of the present invention and that contains a metal oxide in a composite form. Specifically, the contact resistance on the surface of the carbon-based film (C film) is preferably 10 mΩ · cm ² or less.

  More specifically, when the composite metal is Ti, the presence of 1 to 13 at% of Ti in the carbon-based film (C film) is sufficient for hydrophilizing the surface and suppressing contact resistance. Play. Similarly, when the composite metal is Si, the presence of 2 to 15 at% in the carbon-based film (C film) has a sufficient effect for hydrophilizing the surface and suppressing contact resistance.

  The separator for a fuel cell of the present invention has a sufficient effect even if the carbon-based film (C film) formed on the substrate is thin. For example, a film thickness of 10 nm to 100 nm is preferable.

  In the fuel cell separator of the present invention, a diamond-like carbonaceous (DLC) film is suitably used as the carbon-based film (C film). What is necessary is just to combine a metal element simultaneously at the time of formation of a diamond-like carbonaceous (DLC) film | membrane.

  The separator for a fuel cell of the present invention may have another intermediate layer as long as a carbon-based film (C film) containing a composite of metal oxide is formed on the surface. For example, a case where a metal layer is provided between the separator substrate and the carbon-based film (C film) is also included in the present invention.

  As the separator substrate of the fuel cell separator of the present invention, various materials are used. As the metal substrate, SUS or Ti is preferable.

  2ndly, this invention is invention of the manufacturing method of the separator for fuel cells, and is 1 type selected from Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W on a separator board | substrate. A step of forming a carbon-based film (C film) containing the above metal elements in a composite form, and a dry and / or wet hydrophilization treatment of the metal elements composited in the carbon-based film (C film) And a step of forming a metal oxide.

  In the method for producing a fuel cell separator of the present invention, the metal element compounded in the carbon-based film (C film) becomes a metal oxide by dry and / or wet hydrophilization treatment. Here, the dry hydrophilic treatment is preferably exemplified by plasma treatment and ultraviolet irradiation. As the wet hydrophilic treatment, an immersion treatment in which a voltage is applied in a strong acid is preferably exemplified.

  In the present invention, when the composite metal is Ti, it is preferable that Ti is present in the carbon-based film (C film) in an amount of 1 to 13 at%. When the composite metal is Si, Si is carbon-based. It is preferable that 2 to 15 at% is present in the film (C film), the film thickness of the carbon-based film (C film) is preferably 10 nm to 100 nm, and the carbon-based film (C film) is diamond-like carbonaceous (DLC ) It is preferable that the film is a film, the case where a metal layer is provided between the separator substrate and the carbon-based film (C film), and that the separator substrate is preferably SUS or Ti. It is the same.

  In the method for producing a separator for a fuel cell of the present invention, a dry film forming method such as vapor deposition, sputtering, or ion plating is suitable for forming a carbon-based film (C film) containing a composite of metal elements. is there. Specifically, while applying a negative high voltage to the separator substrate in an inert gas atmosphere, the carbon element material and the composite metal are compounded on the separator substrate surface by a dry film forming method. A contained carbon-based film (C film) is formed.

  Third, the present invention is an invention of a fuel cell, in which a polymer electrolyte membrane, an anode and a cathode arranged at positions sandwiching the polymer electrolyte membrane, and a gas flow path for supplying fuel gas to the anode are formed. A solid polymer electrolyte fuel cell comprising at least the anode-side separator and a cathode-side separator having a gas flow path for supplying an oxidant gas to the cathode, wherein the anode-side separator and the cathode-side separator At least one of them is the fuel cell separator.

  Since the fuel cell of the present invention uses a separator that is low in cost and excellent in hydrophilicity, it is excellent in durability and power generation performance.

  In the separator of the present invention, a layer made of a carbon-based film (C film) containing a composite of a specific metal oxide is formed on the surface of the separator in contact with the electrode, thereby draining the polymer solid oxide fuel cell. The improvement of the property and the reduction of the contact resistance at the interface between the separator surface and the electrode are achieved at the same time.

  Specifically, in the present invention, the composite metal oxide fine particles are hydrophilic by forming a carbon-based film (C film) containing a specific metal oxide in a composite on a separator substrate. It helps to drain excess water around the separator. This improves the durability and power generation performance of the fuel cell.

  Further, the present invention provides a carbon oxide film (C film) containing a composite of a specific metal element formed on a separator substrate to form a metal oxide by dry and / or wet hydrophilization treatment. Thus, the hydrophilicity of the fuel cell separator can be easily realized.

  Furthermore, the fuel cell separator having the specific carbon-based film (C film) of the present invention on the surface exhibits excellent characteristics equivalent to those of the graphite material in terms of corrosion resistance and contact resistance with the electrode.

  In the present invention, the separator substrate is preferably made of metal. By using a metal substrate, the present invention takes advantage of the advantages born by applying metal materials to the separator such as cost, formability, productivity, and making the stack smaller and lighter by making the separator thinner and lighter, while the present invention is The present invention solves simultaneously the reduction of contact resistance and the improvement of corrosion resistance, which have been problems when a conventional metal-based material is applied to a separator.

  Compared to other coating materials, the greatest advantage of forming a carbon-based film (C film) such as a diamond-like carbon film on the surface in contact with the electrode of the separator is the carbon-based film (C film) ) In the corrosive environment of a solid polymer electrolyte fuel cell using a fluorine resin proton conductive resin, that is, in a highly acidic corrosive environment in which a small amount of fluorine ions, sulfate ions, etc. are liberated. The system film (C film) itself is chemically and electrochemically stable and does not corrode. Therefore, the coating of the separator surface by the carbon film (C film) is dense, and corrosive substances from the environment contact the separator material. Without the corrosion of the separator material. That is, if a carbon-based film (C film) can be formed on the surface, the problem regarding corrosion resistance can be eliminated from the conditions for selecting the separator material.

On the other hand, in general, a carbon-based film (C film) such as a diamond-like carbon film is formed of a carbon-based film (C film) on the separator surface because sp ³ bonds are the main structure and electron conductivity is not necessarily high. Therefore, the contact resistance between the separator and the electrode increases. Also, the adhesion to the surface of the separator material depends on the material, and particularly the adhesion to the metal material is not necessarily strong. Therefore, the interface is peeled off due to the deformation of the separator that applies stress to the interface between the coating film and the metal material. As a result, corrosion tends to proceed.

  Thus, in order to apply a material in which the carbon-based film (C film) is formed on the surface in contact with the electrode to the fuel cell separator, the electron conductivity of the carbon-based film (C film) is increased (of the film itself). Reduction of resistance and reduction of the interface resistance of the membrane / separator) and improvement of adhesion between the carbon-based membrane (C membrane) and the separator surface are essential. In the present invention, a specific metal is used as the basic structure of the separator. A layer composed of a carbon-based film (C film) containing a composite of oxide is formed on the separator surface in contact with the electrode.

  The film thickness of the carbon-based film (C film) is preferably 10 μm or less, more preferably 5 μm or less, still more preferably 3 μm or less, and most preferably 10 nm to 100 nm. A diamond-like carbon film having a thickness of more than 10 μm is likely to be cracked, and the film is likely to be peeled off as the substrate metal is deformed. On the other hand, a diamond-like carbon film having a thickness of less than 1 nm is highly likely to be difficult to maintain denseness over a wide range.

  The carbon-based film (C film) containing the specific metal of the present invention in a composite form is obtained by using a PVD (Physical Vapor Deposition) process or a CVD (Chemical Vapor Deposition) process generally known in the field of thin film formation technology. It can be formed on a separator substrate.

  A so-called carbon material is often used for the separator substrate. Illustrative examples include graphite materials, glassy carbon, and powder obtained by mixing graphite powder and binder resin with a mold. In order to develop the function as a separator, it is necessary to form a gas flow path on the separator surface, and in order to generate a high voltage practically, it is possible to form a stack in which several hundred cells are stacked. In many cases, from the viewpoint of practical use such as lightening and miniaturization of the stack, it is necessary to satisfy the demands such as weight reduction, thinning of the separator, and high mechanical strength at the same time. The present invention expresses the functions required of a separator such as corrosion resistance and conductivity by forming a carbon-based film (C film) on the surface regardless of the separator base material. In order to meet the requirements, a metal plate is applied to the separator base material, and a carbon-based film (C film) is formed on the surface thereof, thereby satisfying a series of requirements such as corrosion resistance, conductivity, mechanical strength, weight reduction, and thinning. A separator can be obtained.

  It is preferable that the separator of the present invention simultaneously satisfies the reduction in the contact resistance with the electrode and the corrosion resistance, as well as the weight reduction, the downsizing of the stack due to the thin plate of the separator, and the low cost. In order to achieve these needs, the substrate is preferably made of a metal material. Metal materials are required to have mechanical strength as well as basic corrosion resistance. Focusing on corrosion resistance and high strength, stainless steel, titanium, a titanium alloy mainly composed of titanium, or an intermetallic compound of titanium can be suitably used in the present invention. Stainless steel is based on an Fe—Cr alloy containing approximately 11 mass% or more of Cr, and its corrosion resistance is basically due to passivation in a wide potential range by Cr oxide. Stainless steel is used by adding Ni, Mo, Cu, Al, Si, etc. in order to adjust various physical properties according to its application. In the present invention, the basic corrosion resistance and mechanical properties of stainless steel are used. Strength is a necessary condition, and as long as this is satisfied, the composition, structure and the like of stainless steel are not limited.

  Titanium or titanium alloys containing titanium as a main component (including intermetallic compounds) exhibit excellent corrosion resistance due to a stable oxide film (passive film) formed on the metal surface. Therefore, a Ti—Ta alloy added with tantalum or a Ti—Pd alloy can be suitably applied to the present invention.

  Furthermore, from the viewpoint of selecting a metal material focusing on strength, workability, and cost, the present invention is Fe (Fe) or an Fe-based alloy containing Fe as a main component and adding a plurality of elements for adjusting various physical properties. Can be applied to.

  The plate thickness of the metal material is preferably 1 mm or less. If the plate thickness exceeds 1 mm, not only the superiority of the light weight with respect to the graphite material is lost, but also the groove processing of the gas flow path for use as a separator becomes difficult.

  The separator for a fuel cell of the present invention is produced by easily converting a metal element compounded in a carbon-based film (C film) into a metal oxide by dry and / or wet hydrophilization treatment.

Here, the dry hydrophilic treatment is preferably exemplified by plasma treatment and ultraviolet irradiation. Hydroxyl groups that are hydrophilic groups are generated on the surface of the carbon-based film (C film) by plasma treatment or ultraviolet irradiation. As plasma processing conditions, for example,
Feed rate: 10 m / min or less Output: 10 kW or less Number of repeated irradiations: 2 times or more is preferable.

  As the wet hydrophilic treatment, an immersion treatment in which a voltage is applied in a strong acid is preferably exemplified. The strong acid is an acid having a pH of 2 to 4, and when it is desired to increase the processing speed, the acid temperature can be raised to room temperature to 80 ° C. or 500 ppm or less of fluorine can be added. The applied voltage is preferably 1000 mV or less. FIG. 1 schematically shows an immersion treatment in which a voltage is applied in a strong acid.

  The separator for a fuel cell according to the present invention has an anode-side conductive material in which an anode and a cathode electrode are formed on both sides of a proton-conductive polymer electrolyte membrane, and a gas flow path for supplying fuel gas to the anode is formed. The present invention can be applied to a solid polymer electrolyte fuel cell including at least a separator and a cathode-side conductive separator in which a gas flow path for supplying an oxidant gas to the cathode is formed. The separator defined in the present invention can be applied to both the anode-side and cathode-side separators.

  In the fuel cell separator defined in the present invention, since the diamond-like carbon film covering the substrate is excellent in heat resistance, a temperature exceeding 70 to 90 ° C., which is a normal operating temperature of a polymer solid electrolyte fuel cell, In particular, even a temperature of 100 ° C. or higher is applicable to the fuel cell separator.

  Hereinafter, examples of typical separator materials to which the present invention is applied will be described with reference to FIGS.

  The contact angle (index indicating hydrophilicity) of the carbon-based film (C film) formed on the substrate and the evaluation method of the contact resistance are as follows.

[Contact angle]
As shown in FIG. 2, water droplets are attached on the TP, and after 90 seconds, image analysis of the water droplet shape is performed, h and r are measured,
θ = 2θ ₁ = 2 tan ⁻¹ (h / r)
Θ is calculated from the relationship. The smaller this value, the higher the hydrophilicity.

[Contact resistance]
As shown in FIG. 3, in the case of a counter-diffusion layer (carbon paper), the diffusion layer (carbon paper) is sandwiched. In the case of the same type of material, the workpiece and the workpiece are sandwiched at a constant load (surface pressure of 1 MPa). Measure the descent. Since the current is constant at 1 A, V = IR = R from Ohm's law
If the voltage drop is known, the resistance is known.

[Example 1]
Using a Ti substrate, a 10 at% Ti composite diamond-like carbon film (DLC) was formed on the Ti substrate, and the contact angle and contact resistance before and after the diamond-like carbon film was hydrophilized by plasma treatment were examined. .

  FIG. 4 shows the contact angles before and after the hydrophilization treatment by the plasma treatment. Here, as an untreated conventional example, burned carbon is also shown, and a conventional example of an Au-plated substrate is also shown as a provisional target value. Similarly, FIG. 5 shows the contact resistance before and after the hydrophilization treatment by the plasma treatment.

From the results of FIGS. 4 and 5, the substrate on which the 10 at% Ti composite diamond-like carbon film (DLC) is formed has a contact angle significantly reduced by plasma treatment, which is lower than the target value of Au plating. It was able to be lowered to °. Further, the contact resistance increased by the plasma treatment, but could be kept within the target value of 10 mΩ · cm ² .

[Example 2]
It is the composite metal concentration in the carbon-based film (C film) that greatly affects the results of contact angle and contact resistance. In this embodiment, the composite metal concentration is displayed as an atomic concentration.

FIG. 6 shows the results of the composite metal concentration, contact angle (left vertical axis), and contact resistance (right vertical axis) for the Ti composite carbon film (C film). As expected, as the amount of Ti increased, the contact angle decreased and conversely the contact resistance increased. From the results of FIG. 6, as a result of the experiment in which the Ti amount was changed, by making the Ti amount 1 to 13 at%, it is possible to achieve both within a provisional target value of contact angle: 70 ° and contact resistance: 10 mΩ · cm ^2. did it.

FIG. 7 shows the results of the composite metal concentration, contact angle (left vertical axis), and contact resistance (right vertical axis) for the Si composite carbon-based film (C film). Similarly, as the amount of Si increased, the contact angle decreased and conversely the contact resistance increased. From the results of FIG. 7, as a result of the experiment in which the Si amount was changed, it was possible to achieve both within the provisional target values of contact angle: 70 ° and contact resistance: 10 mΩ · cm ² by setting the Si amount to 2 to 15 at%. did it.

  In the separator of the present invention, a layer made of a carbon-based film (C film) containing a composite of a specific metal oxide is formed on the surface of the separator in contact with the electrode, thereby draining the polymer solid oxide fuel cell. And improved contact resistance at the interface between the separator surface and the electrode. This improves the power generation performance and durability of the fuel cell and contributes to the practical use and spread of the fuel cell.

An immersion treatment in which a voltage is applied in a strong acid, which is a wet hydrophilic treatment, is schematically shown. The evaluation method of the contact angle of the carbon-type film | membrane (C film | membrane) formed on the board | substrate is shown. An evaluation method of contact resistance of a carbon-based film (C film) formed on a substrate is shown. The contact angles before and after the diamond-like carbon film was subjected to a hydrophilic treatment by plasma treatment are shown. The contact resistance before and after performing the hydrophilization treatment by the plasma treatment to the diamond-like carbon film is shown. The results of the composite metal concentration, contact angle (left vertical axis) and contact resistance (right vertical axis) are shown for the Ti composite carbon film (C film). The result of a composite metal density | concentration, a contact angle (left vertical axis), and contact resistance (right vertical axis | shaft) is shown about Si composite carbon system film | membrane (C film | membrane).

Claims (20)

  A carbon-based film containing a composite of one or more metal oxides selected from oxides of elements of Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W on a separator substrate A fuel cell separator in which (C film) is formed.   2. The fuel cell separator according to claim 1, wherein a contact angle of the surface of the carbon-based film (C film) is 75 ° or less. 3. The fuel cell separator according to claim 1 or 2, wherein a contact resistance of the surface of the carbon-based film (C film) is 10 mΩ · cm ² or less.   4. The fuel cell separator according to claim 1, wherein the composite metal is Ti and is present in the carbon-based film (C film) in an amount of 1 to 13 at%.   4. The fuel cell separator according to claim 1, wherein the composite metal is Si, and 2 to 15 at% is present in the carbon-based film (C film). 5.   6. The fuel cell separator according to claim 1, wherein the carbon-based film (C film) has a thickness of 10 nm to 100 nm.   The fuel cell separator according to any one of claims 1 to 6, wherein the carbon-based film (C film) is a diamond-like carbonaceous (DLC) film.   The fuel cell separator according to any one of claims 1 to 7, further comprising a metal layer between the separator substrate and the carbon-based film (C film).   9. The fuel cell separator according to claim 1, wherein the separator substrate is made of SUS or Ti.   A carbon-based film (C film) containing one or more metal elements selected from Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W is formed on the separator substrate. And a step of converting the metal element compounded in the carbon-based film (C film) into a metal oxide by dry and / or wet hydrophilic treatment. Production method.   11. The method for producing a fuel cell separator according to claim 10, wherein the dry hydrophilization treatment is a plasma treatment and / or an ultraviolet irradiation.   The method for producing a fuel cell separator according to claim 10, wherein the wet hydrophilization treatment is an immersion treatment in which a voltage is applied in a strong acid.   The method for producing a separator for a fuel cell according to any one of claims 10 to 12, wherein the composite metal is Ti and is present in the carbon-based film (C film) in an amount of 1 to 13 at%.   The method for producing a fuel cell separator according to any one of claims 10 to 12, wherein the complex metal is Si and is present in the carbon-based film (C film) in an amount of 2 to 15 at%.   The method for producing a fuel cell separator according to any one of claims 10 to 14, wherein the carbon-based film (C film) has a thickness of 10 nm to 100 nm.   The method for producing a fuel cell separator according to any one of claims 10 to 15, wherein the carbon-based film (C film) is a diamond-like carbonaceous (DLC) film.   Carbon containing a carbon-based raw material and the composite metal on the surface of the separator substrate in a dry film formation method while applying a negative high voltage to the separator substrate in an inert gas atmosphere. The method for producing a separator for a fuel cell according to any one of claims 10 to 16, wherein a system membrane (C membrane) is formed.   The fuel cell according to any one of claims 10 to 17, wherein a metal layer is formed on the separator substrate, and then a carbon-based film (C film) containing a composite of metal elements is formed. Manufacturing method for the separator.   The method for manufacturing a fuel cell separator according to any one of claims 10 to 18, wherein the separator substrate is made of SUS or Ti.   A polymer electrolyte membrane, an anode and a cathode arranged at positions sandwiching the polymer electrolyte membrane, an anode separator having a gas flow path for supplying a fuel gas to the anode, and an oxidant gas to the cathode 10. A solid polymer electrolyte fuel cell comprising at least a cathode-side separator having a gas flow path for the at least one of the anode-side separator and the cathode-side separator, according to claim 1. A fuel cell, characterized by being a fuel cell separator.

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