JP2003223905A - Separator for polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator for polymer electrolyte fuel cells which can be easily obtained by small precision press equipment while canceling distortion in a large number of gas flow grooves in a metal plate material and plating unevenness on a noble-metal plating layer. <P>SOLUTION: The separator 10 for the polymer electrolyte fuel cells consists of a separator board 11, which is formed with many parallel gas flow grooves of a straight line shape on the surface of the metal plate on which the noble- metal coat is formed, and a plastic frame part 12 of heat-resistance and acid resistance, which fixes a circumference edge of the separator board 11. And, in the plastics frame part 12, gas flow pipes, guide dent grooves, or the like, are formed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separator for a polymer electrolyte fuel cell used as a power source for an electric vehicle, a portable power source, a stationary power source or the like.

[0002]

2. Description of the Related Art A polymer electrolyte fuel cell uses hydrogen as a fuel gas and oxygen-containing air as an auxiliary fuel gas.
It reacts electrochemically to generate electricity and heat.

As shown in FIG. 6, a conventional polymer electrolyte fuel cell is provided with diffusion films 2 and 2 between two separator plates 1 and 1, and an intermediate portion between the diffusion films 2 and 2. It is basically composed of a polymer electrolyte membrane 3 having catalytic reaction layers formed on both sides. The polymer electrolyte membrane 3 has a property of allowing only hydrogen ions to pass. A typical fuel cell is a stack of 10 to 400 cells having this basic structure as a single cell.

A large number of grooves are formed on the surface of the separator plate 1, hydrogen gas is caused to flow into the grooves of the separator plate 1, and air is caused to flow into the grooves of the other separator plates 1. At this time, in the polymer electrolyte membrane 3, the hydrogen ions uniformly diffused in the diffusion membrane 2 and ionized in the catalytic reaction layer pass through the polymer electrolyte membrane 3 and are combined with oxygen to become water. And electricity is generated. The electrons pass through the polymer electrolyte membrane 3 and are taken out from the separator plate 1.

Such a polymer electrolyte fuel cell separator is required to have high conductivity and high corrosion resistance and heat resistance against hydrogen / oxygen redox reaction. The conventional separator plate is usually made of a carbon material such as glassy carbon or expanded graphite, and the gas flow path is manufactured by cutting or molding.

In recent years, graphite containing a thermoplastic resin or a thermosetting resin has been used to reduce the thickness and cost, but there is a limit to this. In order to achieve further weight reduction, thickness reduction, and cost reduction, a method for producing a separator plate in which the surface of a metal such as stainless steel is coated with a noble metal by press molding is currently under development.

[0007]

However, in the method using the conventional carbon material, the material cost and the cutting cost are high, which is an obstacle to practical use. Therefore, a method of manufacturing a metal material in which the surface of a metal such as stainless steel is coated with a precious metal such as gold or platinum by press molding is under research and development. However, since this method also press-molds a large number of gas flow channels and the flat frame portion connected to them, the grooves are drawn and the groove corners have extremely thin noble metal coatings. However, there is a drawback in that it peels off or cracks occur in extreme cases.

Further, there is a problem that the stress during the press molding remains and the whole metal separator plate is easily distorted. As a method of reducing such residual strain, a method of preforming the gas channel groove to be extended more than necessary and compressing it during finish molding can be considered. However, this method has a drawback in that a large-sized precision press machine exceeding 1000 tons is required to press-form a separator plate having a size of 200 mm or more for automobiles. In addition, the method of plating the precious metal after press molding is high in plating cost, distortion is likely to occur during plating, and uneven plating is often generated. There were also drawbacks such as the need to increase the thickness.

Therefore, the present invention can eliminate distortion in a large number of gas passage grooves in the separator and uneven plating in the noble metal plating layer, and can be easily obtained by a small precision press machine for a polymer electrolyte fuel cell. The purpose was to provide a separator.

[0010]

In order to achieve the above-mentioned object, the solid polymer fuel cell separator of the present invention comprises a large number of gas flows that are parallel and linear to the surface of a metal plate on which a precious metal film is formed. It consists of a separator plate provided with a channel groove, and a heat-resistant and acid-resistant plastic frame part for fixing the peripheral edge of this separator plate, and this plastic frame part is provided with a gas flow passage hole, a guide groove, etc. It is characterized by being

In the above-described separator for polymer electrolyte fuel cells of the present invention, the metal separator plate has a large number of gas flow passage grooves having a noble metal coating formed on the surface thereof and a heat-resistant and acid-resistant plastic. Since it is composed of the frame part used, only the gas channel groove of each separator plate is bent, and there is no extreme elongation or cracking like drawing, and the thickness of the precious metal film on the surface is stable. Things are obtained. Therefore, the thickness of the separator plate is also 0.1
Since a thin film having a thickness of about mm can be used, it contributes to the weight reduction and cost reduction of the product.

Further, since the separator plate can be press-molded under feed conditions of 1 to 3 groove pitch, even a large separator plate having a size of more than 200 mm is manufactured by a small press machine of about several tens of tons. It is possible.

Since the frame portion around the separator plate is made of a plastic material and this plastic material acts as an insulator, it is not necessary to consider the insulation of stack bolts for cell stack fixing. Therefore, the separator can be directly fixed with the stack bolt.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A separator 10 for a polymer electrolyte fuel cell according to an embodiment of the present invention is shown in FIG.
The polymer electrolyte fuel cell separator 10 includes a metal plate separator plate 11 and a plastic frame portion 12.

The separator plate 11 is a stainless steel plate having front and back surfaces plated with gold, and has gas passage grooves 12a and 12b formed on the front and back surfaces thereof. These gas flow channels 12a and 12b are formed by pressing the entire plate surface of the separator plate 11 with a small press machine. Moreover, by pressing the groove portions in the gas flow passage grooves 12a and 12b under feed conditions of 1 to 3 groove pitch, a smaller press machine of several tens tons can be applied.

For this reason, the separator plate 11 does not have a drawing portion including the gas flow passage grooves 12a and 12b,
It is obtained with a uniform thickness, and neither peeling of plating of precious metal such as gold nor cracking of the metal plate material occurs. Moreover, strain stress does not occur on the separator plate 11 during press working. The separator 10 is a separator plate 11
Since it is formed by the method described above, a thinner, lighter, and lower cost product can be obtained.

An edge portion of the separator plate 11 is fixed by a plastic frame portion 12. As shown in FIG. 2, the fixing of the separator plate 11 by the plastic frame 12 is performed as follows.
The edge portions of the gas flow channels 11a and 11b and the linear edge portions are molded with the plastic material of the plastic frame portion 12, respectively. As a result, the plastic frame material 12
The periphery of the separator plate 11 is held in a stable state. Reference numeral 12a is an opening portion of the plastic frame portion 12, and the surface of the separator plate 11 directly faces the opening portion 12a.

At the time of molding with this plastic material, a hole portion 11c is provided in the separator plate 11, and the plastic material is filled in the hole portion 11c as well, so that the adhesion between the separator plate 11 and the plastic frame portion 12 is improved. Can be increased. Seal film 17
Are provided to enhance the airtightness between the separator plate 11 and the plastic frame portion 12.

The plastic frame portion 12 has a gas passage pipe 1
3A, 13B, 14A and 14B are formed. The gas passage pipes 13A and 13B are for hydrogen gas, and the gas passage pipes 14A and 14B are for air (oxygen) gas. Also,
Reference numeral 15 is a stack bolt hole, and a plurality of separators 10 can be integrally fixed with a stack bolt to complete a polymer electrolyte fuel cell. In this case, a gas seal 16 is provided between the separators 10 on the surface of the plastic frame portion 12 to seal between the separator 10 and the diffusion film 2.

Guide recesses 12b and 12c are formed on the surface of the plastic frame portion 12, and a path leading to the gas outflow groove 11a through the guide recess 12b is formed.
Therefore, hydrogen gas from the gas passage pipe 13A is introduced into the gas passage groove 11a of the separator plate 11, and this hydrogen gas is converted into hydrogen ions on the surface of the separator plate 11. The hydrogen ions are dispersed in the diffusion membrane 2 and further face the other separator plate 1 through the polymer electrolyte membrane 3.
Reach the 1st side. Air (oxygen) is introduced to the surface of the other separator plate 11 from the gas flow pipe 14A, and the oxygen ions and the hydrogen ions react with each other to generate water. It flows and functions as a fuel cell.

Next, FIG. 4 and FIG. 5 show a polymer fuel cell separator 20 of the present invention. Separator 2
0 indicates that the two separator plates 11 have their gas flow channel grooves 11
The separators 11 and 11 are overlapped with each other so that the positions a and 11b are orthogonal to each other, and the edges of the separator plates 11 and 11 are fixed with a plastic frame portion 21. Reference numeral 21a is an opening portion of the plastic frame portion 21 facing the separator plate 11. 22A, 22B, 23A, and 23B are gas flow path pipes, and function similarly to the case of the separator 10.

In the separator 20, the separator plate 1
1, the outermost gas flow channel groove 11
The gas seal 16 is fitted in a. Therefore, with respect to the diffusion film 2 and the like adjacent to the separator plate 11, the gas seal 16 can be stably held and an airtight state can be secured.

Further, since the airtightness between the plastic frame portion 21 and the separator plate 11 is not important, the plastic frame portion 21 can be separately molded and assembled. Therefore, the plastic frame portion 21 can be molded by a small molding machine.

In the separator 20, for example, cooling air can flow in the gas passage grooves 11a and 11b between the separator plates 11. Therefore, it is advantageous in that it is not necessary to provide a space for the conventional cooling water.

[0025]

As described above, since the polymer fuel cell separator of the present invention is constructed, the following effects are exhibited. Since the polymer fuel cell separator of the present invention is obtained by pressing a metal separator plate, it is thinner, lighter, and lower in cost than conventional carbon separators.

Further, a thin separator plate can be used, and a small press machine of several tens of tons can be applied by pressing under a feed condition of 1 to 3 groove pitch.

In the present invention, since the frame portion is made of a plastic material with respect to the separator plate, the metal plate material is not distorted or cracked during press working, and the thickness of the separator plate is uniform after the press working. The separator can be formed without causing a trouble such as peeling on the precious metal plating.

Further, since the bolt holes for stacking can be provided in the plastic frame portion, the workability of the metal plate material can be reduced, and thus the workability is simpler.

[Brief description of drawings]

FIG. 1 is a plan view of a polymer electrolyte fuel cell separator of the present invention.

FIG. 2 is a partial vertical cross-sectional view illustrating the structure of a fixed portion of a separator plate in a solid polymer fuel cell separator of the present invention.

FIG. 3 is a partial vertical cross-sectional view illustrating a configuration of a fixed portion of a separator plate in a solid polymer fuel cell separator of the present invention.

FIG. 4 is a plan view of another polymer electrolyte fuel cell separator of the present invention.

FIG. 5 is a partial vertical cross-sectional view illustrating the structure of a fixed portion of a separator plate in another separator for a polymer electrolyte fuel cell of the present invention.

FIG. 6 is a partial cross-sectional view illustrating the structure of a conventional polymer electrolyte fuel cell of the present invention.

[Explanation of symbols]

10 separator 11 Separator plate 11a, 11b Gas channel groove 12 plastic frame 12a, 21a Open hole edge 12b, 21b Guide groove 12c Metal plate hole 13A, 13B, 14A, 14B gas flow pipe 15 Stack bolt holes 16 gas seal 17 seal tape 20 separator 21 plastic frame 22A, 22B, 23A, 23B gas flow pipe 24 Stack bolt holes

Claims (3)

[Claims] 1. A separator plate having a plurality of parallel and linear gas flow passage grooves formed on the surface of a metal plate having a precious metal film formed thereon, and a heat-resistant and acid-resistant plastic frame for fixing the peripheral edge of the separator plate. A separator for a polymer electrolyte fuel cell, characterized in that a gas flow passage hole, a guide groove, etc. are formed in the plastic frame portion. 2. The separator for a polymer electrolyte fuel cell according to claim 1, wherein the metal gas flow passage groove is press-molded under feed conditions of 1 to 3 groove pitch. 3. The separator for polymer electrolyte fuel cells according to claim 1, wherein the heat-resistant and acid-resistant plastic frame portion is provided with stack bolt holes.