JP2010055831A - Separator for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely cool an electrode via a separator and enhance corrosion resistance of the separator. <P>SOLUTION: A metallic separator 10 for a fuel cell used, by laminating on a cell stack which is air-cooled together with a unit cell for the fuel cell, includes a separator substrate 1 made of aluminum metal; a nickel layer 2 formed on the surface of the separator substrate 1; a conductive resin layer 3 formed on the surface of the nickel layer 2; and a water-repellent layer 4 formed on the surface of the conductive resin layer 3. The separator substrate 1 includes a separator body part 11, having a reaction part arranged opposite to an anode and a cathode which compose the unit cell of the fuel cell, and a heat-sink part formed integrally, in at least a part of the periphery of the separator body part 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell separator used in a polymer electrolyte fuel cell. The fuel cell separator of the present invention is particularly suitable for application to an air-cooled fuel cell system having a small size, light weight and simple structure.

  In recent years, fuel cells capable of realizing clean exhaust and high energy efficiency have attracted attention. In particular, the polymer electrolyte fuel cell has characteristics such as high output density and low operating temperature. For this reason, it has become practical to use a fuel cell system using a polymer electrolyte fuel cell as a small and light power source for a mobile body or a home.

  A fixed polymer fuel cell system generally includes a battery stack, a fuel cylinder that supplies fuel to the battery stack, and a cooling means for cooling the battery stack.

  The battery stack is formed by stacking a plurality of unit battery cells sandwiched between conductive separators. The unit battery cell is made of a membrane / electrode assembly (MEA). The membrane / electrode assembly includes a solid polymer electrolyte membrane made of a polymer ion exchange membrane, an anode (fuel electrode) made of a catalyst layer and a fuel gas diffusion layer adjacent to one surface of the solid polymer electrolyte membrane, and a solid The cathode is composed of a catalyst layer and an oxidant gas diffusion layer adjacent to the other surface of the polymer electrolyte membrane.

  In the part (reaction part) that faces the electrode of the separator, a supply gas flow path for fuel gas, oxidant gas, etc. is formed between the electrodes, so that there are a large number of projections, grooves, etc. for forming the gas flow path. Is formed. Further, the separator has a role as a current collector and a role as a gas passage forming material. For this reason, as a characteristic of a separator, electroconductivity, current collection property, and permeation resistance to hydrogen and oxygen are required.

  The separator is generally made of a metal material having high strength and workability, such as stainless steel, titanium, and aluminum. However, even in a polymer electrolyte fuel cell operating at a relatively low temperature, the separator is exposed to near-saturated water vapor at a temperature of 70 to 90 ° C. For this reason, in the separator using a metal material, an oxide film due to corrosion is easily generated on the surface thereof. As a result, there is a problem that the contact resistance between the generated oxide film and the electrode is increased, and the current collecting performance of the separator is lowered.

  Therefore, a metal separator in which a conductive resin layer is provided on the surface of a separator substrate is known (for example, see Patent Document 1). This metal separator is excellent in conductivity and current collecting property, and at the same time, is excellent in moldability, strength and corrosion resistance. However, depending on the type of the metal material of the separator substrate, further improvement in corrosion resistance is desired.

On the other hand, a fuel cell system that includes a cooling fan and cools a battery stack with air is known (for example, see Patent Document 2). In this fuel cell system, since the cell stack is cooled by the air from the cooling fan, it is possible to suppress thermal deterioration of the electrodes (such as sintering of the catalyst metal). However, in order to more reliably suppress thermal deterioration of the electrode, it is desired to cool the electrode more reliably by a cooling fan via the separator.
JP 2006-269090 A JP 2007-265937 A

  The present invention has been made in view of the above circumstances, and provides a metal separator for a fuel cell that can more reliably cool an electrode through the separator and can further improve corrosion resistance. Objective.

  A metal separator for a fuel cell according to the present invention that solves the above problems is a metal separator for a fuel cell that is used by being stacked together with a unit battery cell on an air-cooled battery stack, and an anode and a cathode that constitute the unit battery cell A separator substrate having a reaction portion disposed opposite to the separator, a heat sink portion integrally formed on at least a part of the periphery of the separator body portion, a separator substrate made of an aluminum-based metal, and the separator A nickel layer formed on the surface of the separator body of the substrate; a conductive resin layer formed on the surface of the nickel layer; and a water repellent layer formed on the surface of the conductive resin layer. It is characterized by being.

  Here, the aluminum-based metal is aluminum or an aluminum alloy.

  In the fuel cell metal separator of the present invention, the separator substrate is made of an aluminum-based metal. In addition, the metal separator for a fuel cell according to the present invention has a heat sink on the periphery of the separator main body arranged to face the anode and the cathode. Aluminum-based metals have a relatively high thermal conductivity. For this reason, the heat of an anode and a cathode is efficiently transmitted from a reaction part to a heat sink part. Since the heat from the cooling fan is likely to hit the heat sink, the heat sink is easily cooled. For this reason, the heat sink part which became hot when the heat of the anode and the cathode was transmitted from the reaction part can be efficiently cooled by the cooling fan. Therefore, when the battery stack is cooled by applying air from the cooling fan to the heat sink portion, the anode and the cathode can be more reliably cooled via the separator.

  In the metal separator for a fuel cell of the present invention, a nickel layer, a conductive resin layer, and a water repellent layer are formed on the surface of the separator main body of the separator substrate. For this reason, the metal separator of this invention exhibits high corrosion resistance and current collection property by the action of these three layers, as shown in the examples described later.

  The metal separator for a fuel cell of the present invention preferably has at least one of the structures shown in the following items (1) to (3). The metal separator for a fuel cell of the present invention may have the configuration shown in each item of (1) to (3) below, or the configuration shown in each item of (1) to (3). Two or more may be combined.

  (1) The nickel layer, the conductive resin layer, and the water repellent layer are not formed in the heat sink portion.

  The heatsink part does not need corrosion resistance. On the other hand, it is desirable that heat can be efficiently dissipated in the heat sink portion directly exposed to air from the cooling fan. In this respect, according to the present configuration in which the nickel layer, the conductive resin layer, and the water repellent layer are not formed on the heat sink portion, the separator substrate made of an aluminum-based metal having a high thermal conductivity is exposed. Is not hindered by the nickel layer, the conductive resin layer and the water repellent layer. For this reason, heat can be efficiently radiated from the heat sink portion.

  In addition, waste of material costs due to the formation of the nickel layer, the conductive resin layer, and the water repellent layer in the heat sink portion can be eliminated, which is advantageous in terms of cost.

  (2) The conductive resin layer has a thickness of 10 to 30 μm.

  (3) The water repellent layer has a thickness of 1 to 3 μm.

  Therefore, according to the metal separator for a fuel cell of the present invention, the electrode can be cooled more reliably through the separator, and the corrosion resistance of the separator can be further improved. Therefore, it is possible to extend the life of the electrode and the separator.

  Hereinafter, embodiments of the metal separator for a fuel cell of the present invention will be described in detail. In addition, embodiment described is only one Embodiment, The metal separator for fuel cells of this invention is not limited to the following embodiment. The metal separator for a fuel cell of the present invention can be implemented in various forms with modifications, improvements, etc. that can be made by those skilled in the art without departing from the gist of the present invention.

(Embodiment 1)
The metal separator 10 for a fuel cell according to the first embodiment is a heat sink integrated separator in which a heat sink portion is integrally formed.

  As shown in the schematic cross-sectional view of FIG. 1, the metal separator 10 includes a separator substrate 1, a nickel layer 2 formed on the surface of the separator substrate 1, and a conductive resin layer formed on the surface of the nickel layer 2. 3 and a water repellent layer 4 formed on the surface of the conductive resin layer 3.

  The separator substrate 1 is made of an aluminum-based metal, that is, aluminum or an aluminum alloy.

  As shown in the plan view of FIG. 2, the separator substrate 1 includes a square separator body 11 and a rectangular heat sink 12 integrally formed on a part of the periphery of the separator body 11. ing.

  The separator main body 11 has a rectangular reaction part 111 at a substantially central part of the separator main body 11. The reaction unit 111 is disposed so as to face an anode and a cathode constituting a unit battery cell 20 described later when the metal separator 10 is incorporated in a battery stack 30 described later. On both the front and back surfaces of the reaction section 111, a number of gas flow path forming grooves 111a for supplying fuel gas to the anode and oxidant gas to the cathode are formed. The separator body 11 has a plurality (four in this embodiment) of circular holes 11a at the four corners and a plurality (six in this embodiment) of rectangular holes 11b at the peripheral side. . When the metal separator 10 is incorporated in the battery stack 30, a manifold (not shown) is disposed in the rectangular hole 11 b. This manifold forms a gas flow path for supplying fuel gas, a gas flow path for supplying oxidant gas, and a drainage path for discharging water generated by the cell reaction. The circular hole 11 a is a bolt insertion hole for stacking and fixing the metal separator 10 and the like to form the battery stack 30.

  In the separator substrate 1 of the first embodiment, one rectangular (or strip-shaped) heat sink portion 12 is integrally formed at one end (one side) of the square separator body portion 11. The heat sink portion 12 does not face the anode and the cathode constituting the unit battery cell 20 when the metal separator 10 is incorporated in the battery stack 30. That is, when the metal separator 10 is incorporated in the battery stack 30, the heat sink portions 12 of the adjacent metal separators 10 face each other with a predetermined interval.

  Although the formation method of the separator substrate 1 is not particularly limited, casting such as die casting or pressing can be used. The thickness of the separator substrate 1 is not particularly limited, and can be about 2 to 5 mm.

  The nickel layer 2, the conductive resin layer 3, and the water repellent coating layer 4 are not formed on the heat sink portion 12 of the separator substrate 1. That is, the nickel layer 2, the conductive resin layer 3, and the water repellent layer 4 are formed only on the separator body 11 portion of the separator substrate 1. Further, the nickel layer 2, the conductive resin layer 3, and the water repellent layer 4 are formed on both front and back surfaces of the separator main body 11 portion of the separator substrate 1.

  In order to form the nickel layer 2, the conductive resin layer 3, and the water repellent layer 4 only on the separator body portion 11, for example, the nickel layer 2, conductive layer is covered with the heat sink portion 12 covered with a masking tape. The formation process of each layer of the water-soluble resin layer 3 and the water repellent layer 4 may be performed, and then the masking tape may be peeled off.

  Although the formation method of the nickel layer 2 is not specifically limited, The nickel layer 2 can be suitably formed by electroplating or electroless plating.

  An oxide film is easily formed on the surface of the separator substrate 1 made of an aluminum-based metal. When an oxide film is formed on the surface of the separator substrate 1, the electrical resistance of the metal separator 10 increases. The nickel layer 2 prevents an oxide film from being formed on the surface of the separator substrate 1 made of an aluminum-based metal. Therefore, by forming the nickel layer 2 on the surface of the separator substrate 1, it is possible to prevent an increase in electrical resistance due to the formation of an oxide film.

  If the thickness of the nickel layer 2 is too thin, the effect of forming the nickel layer 2 becomes insufficient. On the other hand, even if the nickel layer 2 is made too thick, no further effect of forming the nickel layer 2 can be expected, which is disadvantageous in terms of cost. Therefore, the thickness of the nickel layer 2 is preferably 1 to 10 μm, and more preferably 5 to 10 μm.

  The type of the conductive resin layer 3 is not particularly limited. For example, even if a metal-based conductive resin layer containing metal particles as a conductive substance in a resin binder, carbon as a conductive substance in the resin binder is used. The carbon type conductive resin layer containing a system particle may be sufficient. Although the kind of resin binder is not specifically limited, A phenol resin with high heat resistance, an epoxy resin, an acrylic resin, and a fluororesin can be used suitably.

  The method for forming the conductive resin layer 3 is not particularly limited. For example, after the metal-based conductive paint or the carbon-based conductive paint is applied to the surface of the nickel layer 2 by dipping, spraying, brushing, electrodeposition or the like. Can be baked. As baking conditions, it can be set as temperature: about 120-180 degreeC, time: about 30-60 minutes. In addition, the film thickness of the conductive resin layer 3 can be increased by repeating the coating and baking of the conductive paint.

  The conductive resin layer 3 improves the corrosion resistance of the metal separator 10 while suppressing a decrease in the conductivity and current collecting property of the metal separator 10. If the thickness of the conductive resin layer 3 is too thin, the effect of forming the conductive resin layer 3 becomes insufficient. On the other hand, if the conductive resin layer 3 is made too thick, the sheet resistance (contact resistance) of the metal separator 10 increases, so that the conductivity and current collection performance of the metal separator 10 decrease. Therefore, the thickness of the conductive resin layer 3 is preferably 10 to 30 μm, and more preferably 15 to 25 μm.

  The type and formation method of the water repellent layer 4 are not particularly limited. For example, a silicone-based or fluorine-based water-repellent paint is applied to the surface of the conductive resin layer 3 by dipping, spraying, brushing or electrodeposition. Can be baked. As baking conditions, it can be set as temperature: about 150-200 degreeC, time: about 30-60 minutes. In addition, the film thickness of the water repellent layer 4 can be increased by repeating the application and baking of the water repellent paint.

  The conductive resin layer 3 is likely to crack when the conductive resin layer 3 is formed (baked). When the water-repellent layer 4 is formed on the surface of the conductive resin layer 3, cracks in the conductive resin layer 3 are filled with a water-repellent paint, so that moisture is externally applied to the nickel layer 2 through the cracks in the conductive resin layer 3. Can be prevented from reaching. Further, even if there is a gap due to a crack in the conductive resin layer 3, it is possible to prevent moisture from entering the crack of the conductive resin layer 3 from the outside due to the water repellent effect in the water repellent layer 4. Therefore, the water repellent layer 4 formed on the surface of the conductive resin layer 3 enhances the corrosion resistance of the metal separator 10.

  If the thickness of the water repellent layer 4 is too thin, the effect of forming the water repellent layer 4 becomes insufficient. On the other hand, if the water-repellent layer 4 is too thick, the sheet resistance of the metal separator 10 (contact resistance) increases, so that the conductivity and current collection performance of the metal separator 10 decrease. Therefore, the thickness of the water repellent layer 4 is preferably 1 to 3 μm, and more preferably 1 to 2 μm.

  Here, when the water repellent layer 4 is formed on the surface of the conductive resin layer 3, it is applied to the surface of the conductive resin layer 3 from the viewpoint of facilitating the water-repellent paint to enter the cracks of the conductive resin layer 3. It is preferable to lower the viscosity of the water repellent paint to some extent.

  As shown in FIG. 3, the metal separator 10 according to the first embodiment having the above configuration is stacked together with a plurality of unit battery cells 20 to form a battery stack 30. The battery stack 30 and an unillustrated fuel cylinder and cooling fan 40 constitute an air-cooled solid polymer fuel cell system.

  The unit battery cell 20 includes a solid polymer electrolyte membrane made of a polymer ion exchange membrane, an anode (fuel electrode) made of a catalyst layer and a fuel gas diffusion layer adjacent to one surface of the solid polymer electrolyte membrane, as in the conventional case. The membrane electrode assembly (MEA) comprising a catalyst layer and an oxidant gas diffusion layer adjacent to the other surface of the solid polymer electrolyte membrane and a cathode (oxygen electrode).

  The cooling fan 40 can be configured by a cross flow fan extending in the stacking direction of the unit battery cells 20 in the battery stack 30 or a plurality of axial fans (centrifugal fans) arranged side by side in the stacking direction. Cooling air is sent from the cooling fan 40 toward the battery stack 30. At this time, it is preferable to arrange the cooling fan so that the cooling air from the cooling fan directly hits each heat sink portion 12 of each metal separator 10 in the battery stack 30.

  In the metal separator 10 for a fuel cell according to the first embodiment, the separator substrate 1 is made of an aluminum-based metal, and the heat sink portion 12 is provided at the periphery of the separator main body portion 11 disposed to face the anode and the cathode of the unit battery cell 20. Have Aluminum-based metals have a relatively high thermal conductivity. For this reason, the heat of the anode and the cathode is efficiently transmitted from the reaction part 111 of the separator main body part 11 to the heat sink part 12. The air from the cooling fan 40 directly hits the heat sink 12. For this reason, the heat sink 12 that has been heated by the heat of the anode and the cathode transmitted from the reaction unit 111 can be efficiently cooled by the cooling fan 40. Therefore, if the battery stack 30 is cooled so that the air from the cooling fan 40 directly hits the heat sink portion 12, the anode and the cathode can be more reliably cooled via the metal separator 10.

  Moreover, in the metal separator 10 of Embodiment 1, the nickel layer 2, the conductive resin layer 3, and the water repellent layer 4 are formed on the surface of the separator substrate 1. For this reason, this metal separator 10 exhibits high corrosion resistance and current collection by the action of these three layers.

  Further, in this metal separator 10, the nickel layer 2, the conductive resin layer 3, and the water repellent layer 4 are not formed on the portion of the heat sink portion 12 that basically does not require corrosion resistance. That is, in the heat sink portion 12, the separator substrate 1 is exposed from an aluminum metal having a high thermal conductivity. For this reason, heat dissipation from the heat sink portion 12 is not hindered by the nickel layer 2, the conductive resin layer 3, and the water repellent layer 4. Therefore, heat can be radiated more efficiently from the heat sink portion 12. Furthermore, the waste of material costs due to the formation of the nickel layer 2, the conductive resin layer 3, and the water repellent layer 4 on the heat sink portion 12 can be eliminated, which is advantageous in terms of cost.

  Therefore, according to the metal separator 10 for fuel cells of Embodiment 1, the anode and the cathode through the metal separator 10 can be cooled more reliably, and the corrosion resistance of the separator can be further improved. For this reason, it becomes possible to lengthen the electrode life by suppressing thermal deterioration of the anode and the cathode. In addition, the life of the metal separator 10 can be extended.

(Embodiment 2)
In the separator substrate 1 according to the second embodiment, as shown in FIG. 4, a pair of heat sink portions 12, 12 are integrally formed at both ends (two opposite sides) of the square separator body portion 11. The heat sink portion 12 does not face the anode and the cathode constituting the unit battery cell when the metal separator 10 is incorporated in the battery stack. That is, when the metal separator 10 is incorporated into the battery stack, the heat sink portions 12 of the adjacent metal separators 10 face each other with a predetermined interval.

  Since other configurations are the same as those of the first embodiment, the description thereof is omitted.

  Therefore, the metal separator 10 of Embodiment 2 also has the same effect as the metal separator 10 of Embodiment 1.

(Embodiment 3)
In the separator substrate 1 according to the third embodiment, as shown in FIG. 5, the annular heat sink portion 12 is integrally formed on the entire circumference of the peripheral edge of the square separator body portion 11. The heat sink portion 12 does not face the anode and the cathode constituting the unit battery cell when the metal separator 10 is incorporated in the battery stack. That is, when the metal separator 10 is incorporated into the battery stack, the heat sink portions 12 of the adjacent metal separators 10 face each other with a predetermined interval.

  Since other configurations are the same as those of the first embodiment, the description thereof is omitted.

  Therefore, the metal separator 10 of Embodiment 3 also has the same operational effects as the metal separator 10 of Embodiment 1.

(Other embodiments)
In the first and second embodiments, the example in which the nickel layer 2, the conductive resin layer 3, and the water repellent layer 4 are not formed on the heat sink portion 12 has been described. However, the entire separator substrate 1, that is, the separator main body portion. The nickel layer 2, the conductive resin layer 3, and the water repellent layer 4 may be formed on the entire 11 and the heat sink portion 12. When the nickel layer 2, the conductive resin layer 3, and the water repellent layer 4 are formed on the entire separator substrate 1, masking for preventing the nickel layer 2, the conductive resin layer 3, and the water repellent layer 4 from being formed on the heat sink portion 12. Processing or the like becomes unnecessary, and the manufacturing process can be reduced.

Example 1
A metal separator 10 of Example 1 was manufactured according to Embodiment 1.

  First, a metal substrate 1 having a predetermined shape made of aluminum was formed by die casting. The thickness of the metal substrate 1 was 2 mm.

  And the nickel layer 2 of thickness 5 micrometers was formed in the whole metal substrate 1 (the whole separator main-body part 11 and the heat sink part 12) by electroplating.

  Next, after ultrasonic cleaning is performed under conditions of a temperature of about 40 ° C. and a time of about 10 minutes, dipping, blowing off, and baking are repeated twice to form a conductive layer having a thickness of 20 μm on the surface of the nickel layer 2. Resin layer 3 was formed. The baking conditions were temperature: 160 ° C. and time: 45 minutes. In addition, the trade name “Everyum 30CE” (manufactured by Nippon Graphite Industry Co., Ltd.) was used as the conductive paint. This conductive paint contains graphite particles. The resin binder in this conductive paint is a phenol resin.

  Finally, a water repellent layer 4 having a thickness of 1 to 2 μm was formed on the surface of the conductive resin layer 3 by dipping, natural drying and baking. The baking conditions were temperature: 160 ° C. and time: 45 minutes. Further, a water-repellent paint having a trade name of “Silicone Coating KR251” (manufactured by Shin-Etsu Chemical Co., Ltd.) diluted to 2% concentration was used.

(Example 2)
A metal separator 10 of Example 2 was manufactured in the same manner as Example 1 except that the thickness of the nickel layer 2 was 10 μm.

(Example 3)
Example 3 is the same as Example 1 except that the thickness of the separator substrate 1 is 5 mm, the thickness of the nickel layer 2 is 10 μm, and the thickness of the conductive resin layer 3 is 10 μm. A metal separator 10 was produced.

(Comparative Example 1)
A metal separator of Comparative Example 1 was produced in the same manner as in Example 1 except that the water repellent layer 4 was not formed.

(Comparative Example 2)
A metal separator of Comparative Example 2 was produced in the same manner as in Example 1 except that the thickness of the conductive resin layer 3 was 30 μm and the water repellent layer 4 was not formed.

(Comparative Example 3)
A metal separator of Comparative Example 3 was produced in the same manner as in Example 1 except that the thickness of the nickel layer 2 was 10 μm and the water repellent layer 4 was not formed.

(Comparative Example 4)
The metal separator of Comparative Example 4 was prepared in the same manner as in Example 1 except that the thickness of the nickel layer 2 was 10 μm, the thickness of the conductive resin layer 3 was 30 μm, and the water repellent layer 4 was not formed. Manufactured.

(Comparative Example 5)
A metal separator of Comparative Example 5 was produced in the same manner as in Example 1 except that a metal substrate made of stainless steel was used and the water repellent layer 4 was not formed.

(Comparative Example 6)
A metal separator of Comparative Example 6 was produced in the same manner as in Example 1 except that the nickel layer 2 and the water repellent layer 4 were not formed.

(Comparative Example 7)
Example 1 is the same as Example 1 except that the thickness of the separator substrate 1 is 5 mm, the thickness of the nickel layer 2 is 10 μm, the thickness of the conductive resin layer is 10 μm, and the water-repellent layer 4 is not formed. Thus, a metal separator of Comparative Example 7 was produced.

(Comparative Example 8)
A metal separator of Comparative Example 8 was produced in the same manner as in Example 1 except that the thickness of the separator substrate 1 was 5 mm, the thickness of the nickel layer 2 was 10 μm, and the water repellent layer 4 was not formed.

(Comparative Example 9)
Example 1 except that the thickness of the separator substrate 1 is 5 mm, the thickness of the nickel layer 2 is 10 μm, the thickness of the conductive resin layer is 30 μm, and the water-repellent layer 4 is not formed. A metal separator of Comparative Example 9 was produced.

(Evaluation of corrosion resistance)
Corrosion resistance was evaluated for the metal separator 10 of Examples 1 and 2 and the metal separators of Comparative Examples 1 to 4. This was done by immersing the sample in a pH 3 sulfuric acid aqueous solution and measuring the endurance time until the corrosion current was detected. These results are shown in Table 1.

  As is clear from Table 1, the durability time in the metal separators 10 of Examples 1 and 2 was 5000 hours or more, as in Comparative Example 5 using a metal substrate made of stainless steel. 10 has been demonstrated to have very high corrosion resistance.

(Evaluation of sheet resistance)
The sheet resistance of the metal separator 10 of Example 2 and the metal separators of Comparative Examples 3 and 6 were evaluated. In this evaluation, a current was passed through the electrode surface, and the voltage at that time was measured to obtain a resistance value. These results are shown in Table 2.

From Table 2, the area resistance (contact resistance) of the metal separator was increased by forming the water repellent layer 4, but the area resistance of 70 mΩ · cm ² in the metal separator 10 of Example 2 can be used as a separator. It is a range.

(Relationship between thickness of conductive resin layer and sheet resistance)
About the metal separator of Comparative Examples 7-9, it carried out similarly to the above, and evaluated sheet resistance. These results are shown in Table 3.

  From Table 3, the area resistance (contact resistance) of the metal separator increased as the conductive resin layer 3 became thicker.

2 is a schematic cross-sectional view of a metal separator according to Embodiment 1. FIG. 3 is a plan view of a metal separator according to Embodiment 1. FIG. It is a top view which shows the example which incorporated the metal separator which concerns on Embodiment 1 in a battery stack with a unit battery cell, and incorporated this battery stack in the polymer electrolyte fuel cell system. 6 is a plan view of a metal separator according to Embodiment 2. FIG. 6 is a plan view of a metal separator according to Embodiment 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Separator board | substrate 2 ... Nickel layer 3 ... Conductive resin layer 4 ... Water-repellent layer 10 ... Metal separator 11 ... Separator main-body part 12 ... Heat sink part 20 ... Unit battery cell 30 ... Battery stack 40 ... Cooling fan 111 ... Reaction part

Claims (4)

A fuel cell metal separator used by being laminated with unit battery cells in an air-cooled battery stack,
A separator body having a reaction portion disposed opposite to an anode and a cathode constituting the unit battery cell; and a heat sink portion integrally formed on at least a part of a peripheral edge of the separator body, aluminum A separator substrate made of a metal,
A nickel layer formed on the surface of the separator body of the separator substrate;
A conductive resin layer formed on the surface of the nickel layer;
A fuel cell metal separator, comprising: a water repellent layer formed on a surface of the conductive resin layer.   2. The metal separator for a fuel cell according to claim 1, wherein the nickel layer, the conductive resin layer, and the water repellent layer are not formed in the heat sink portion.   The metal separator for a fuel cell according to claim 1 or 2, wherein the conductive resin layer has a thickness of 10 to 30 µm.   The fuel cell separator according to any one of claims 1 to 3, wherein the water repellent layer has a thickness of 1 to 3 µm.

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