JP2003282098A - Fuel cell - Google Patents

Abstract

(57) [Summary] [Problem] To provide a PEFC employing a separator having a configuration that makes the best use of the characteristics of a metal material. SOLUTION: A metal material is formed into a super-flat serrated fin, which is used as a passage member together with a thin plate material serving as an insulating partition material to form a separator, and fin undulations (ridges).
Direction to ((Corrugation direction of fin)
With a configuration that allows gas to flow through, the material has excellent corrosion resistance, such as stainless steel, while maintaining electrical and thermal conductivity while improving fuel gas dispersion and permeability, and setting the passage height as low as possible. it can.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stack type fuel cell in which a large number of fuel cells are stacked with a separator interposed between them. A metallic material such as stainless steel is adopted as a separator material and processed into a specific fin shape. By doing so, it is possible to reduce the height of the passage, and to a fuel cell in which the gas passing effect is significantly improved.

[0002]

2. Description of the Related Art A solid polymer electrolyte fuel cell (PEFC) using a polymer as an electrolyte can obtain a low operating temperature of 100 ° C. or lower and an energy conversion efficiency of more than 50%, and therefore can be used for automobile and household cogeneration. Various developments have been made for use in the system.

The structure of the PEFC is such that by arranging a fuel electrode (anode) and an air electrode (cathode) on both sides of the solid polymer electrolyte membrane and bringing hydrogen into contact with the fuel electrode and oxygen into the air electrode, hydrogen is produced. Is converted into hydrogen ions by the catalytic reaction of the anode and moves in the electrolyte membrane, and is reacted with oxygen by the catalytic reaction of the cathode to become water.

This electrolyte membrane conducts hydrogen but not electrons. On the other hand, in order to supply hydrogen to the fuel electrode and oxygen to the air electrode, a separator is arranged in front of each electrode surface to form a passage. The electrons flow to this separator, travel through an external circuit, and move from the anode to the cathode, and the electron transfer generates electric energy.

[0005]

In general, PEFC has a separator sandwiched between cells as described above to shut off fuel gas and air, and a gasket is placed between the separator and the solid polymer electrolyte membrane for lamination. With such a configuration, the gas flow is devised so that hydrogen is supplied to the anode and oxygen is supplied to and contact with the cathode in each gasket.

In a stack type fuel cell in which a gasket, a polymer solid electrolyte membrane (membrane electrode assembly, MEA), and a gasket are arranged between a pair of separators to form one unit cell, and a large number of these are stacked, the above gas is used. Since the separator for shutting off is required to improve the gas flow together with characteristics such as electrical conductivity, thermal conductivity, and corrosion resistance, many materials are selected for its design and its form. Ingenuity is needed.

At present, the separator is a combination of glassy carbon obtained by impregnating and sintering phenol resin into cellulose and porous carbon having a flow path, and isotropic carbon having a pore size of μm order. A type in which a flow path is cut and formed by impregnating a phenol resin has been put into practical use.

On the other hand, the practical use of metals which are considered to be convenient for forming gas passages, particularly aluminum alloys and stainless steel materials, has been examined, but they are required to have electrical conductivity, thermal conductivity, corrosion resistance and the like. It is difficult to determine the shape of the gas flow path while making it good, and to shape it efficiently.

An object of the present invention is to employ a metallic material as a separator in PEFC, and an object thereof is to provide a fuel cell employing a separator having a constitution in which the characteristics of the metallic material are maximized.

[0010]

Means for Solving the Problems The inventors of the present invention selected a material excellent in corrosion resistance from the form of a separator made of a metal material,
In particular, as a result of various studies aimed at improving the dispersibility and passage of the fuel gas while ensuring electrical conductivity and thermal conductivity and setting the passage height as low as possible, as a result, the metal material is a super flat serrated fin. It was found that the above-mentioned object can be achieved by molding into a separator and combining this with a thin plate material serving as an insulating partition material as a passage member to form a separator.

Further, the inventors of the present invention flow gas in a direction perpendicular to a large number of offset tunnels having a super-flat serrated fin as a gas passage member, in other words, against fin waviness (ridges). It is possible to remarkably improve the dispersibility without increasing the passage resistance of the fuel gas by configuring the gas to flow in the direction perpendicular to the vertical direction (the corrugation direction of the fins). We have found that the perforated type can also be adopted.

Further, the inventors have found that the current collecting characteristics can be greatly improved by providing a conductive thin film on the wavy top of the fin where the serrate type fin and the thin plate member abut and on the thin plate member side. Furthermore, they have found that stainless steel, heat-resistant alloys, corrosion-resistant alloys, etc. can be used as the material, and as a preferable configuration, the plate thickness can be 0.1 mm or less and the fin height can be 1 mm or less, and the present invention has been completed.

That is, according to the present invention, the fin height is 2 mm.
The following serrate-type fins or perforate-type fins are used as gas passage members in contact with a thin plate material, and a separator having a structure in which gas flows in a direction orthogonal to the undulations (ridges) of the fins (corrugation direction of the fins) is provided. It is a fuel cell characterized by the above.

Further, the present invention is directed to the fuel cell having the above-mentioned structure: An offset pitch cut in the waviness (ridge) direction of the serrate type fin or a perforation position provided in the waviness (ridge) direction of the perforate type fin. The pitch is variable pitch, the conductive thin film is formed on at least the fin tops, and the conductive thin film is formed on at least the positions of the thin plate members in contact with the fin tops.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a known MEA is used.
(Membrane / electrode assembly), that is, a structure in which an anode (fuel electrode = hydrogen electrode) film and a cathode (air electrode = oxygen electrode) film are formed and arranged on both sides of a polymer solid electrolyte membrane to form one substrate Can be adopted. Also, any known laminate other than MEA can be adopted.

For example, as a commercially available MEA structure, a polymer film using a perfluorosulfonic acid type polymer, and carbon and carbon fine particles carrying a Pt type catalyst are used for the anode and cathode, that is, a Pt type. In some cases, a catalyst is dispersed in a polymer electrolyte polymer, screen-printed on a carbon paper made of carbon fiber, and this is thermocompression-bonded to both surfaces of a polymer film to form a bonded body.

The fin material forming the gas passage member of the separator, which is a feature of the present invention, may be any metal or alloy material capable of forming fins, and may be the entire surface or the required material. A corrosion resistant film or a conductive film can be formed on the part. Preferred materials include stainless steels of various compositions, corrosion resistant alloy steels, and the like.

As the partition thin plate material, any known metal or alloy material of the same material as the fin or of a different material can be used as long as it can be punched and variously molded. If necessary, an insulating film, a corrosion resistant film, or a conductive film can be formed on the entire surface or a required portion. Preferred materials include stainless steels of various compositions, corrosion resistant alloy steels, and the like.

For the insulating film, the corrosion resistant film, and the conductive film, any known material such as a metal, an alloy, a ceramics, a resin material, or a composite material thereof having a desired function can be adopted.

Structure 1 Explaining an example of the structure of the PEFC according to the present invention, as shown in FIG. 1, the MEA is sandwiched and the separators are arranged to face each other on both main surfaces thereof. In the separator 1, two kinds of gas passage members 3 and 4 having different fin shapes are respectively arranged in contact with both main surfaces of a thin plate material 2 serving as a core material.
Passage holes 6a, 6b, 7a, 7b are formed in the upper and lower parts of the upper and lower portions, and the gas passage members 3, 4 are formed on the plate main surface between the upper and lower passage holes.
And the sealing members 8 and 9 having a required width are arranged on the entire outer peripheral portion of the thin plate member 1 outside the passage hole.

The gas passage member 3 disposed on one main surface of the separator 1 abuts on the anode film of the MEA 10 to form a fuel passage for passing hydrogen of fuel through the gas passage member, and the gas passage member disposed on the other main surface. Reference numeral 4 forms an air passage in contact with the cathode film of the MEA 10 to allow oxygen in the air to pass therethrough.

Gas passage member 3 for forming a fuel passage
1A, as shown in FIG. 1A, is composed of serrate type fins and is arranged so that the fin waviness is horizontal. For example, when hydrogen of fuel is flowed down from upper passage hole 6a to lower passage hole 7b, Hydrogen can be immediately diffused throughout the passage and uniformly flowed down, and the oxidation reaction of hydrogen proceeds on the entire surface of the anode film having the catalyst of MEA 10. Although not shown, a perforate fin having a structure in which holes are appropriately arranged in each ridge portion of the corrugated fin may be used instead of the serrate fin.

Gas passage member 4 for forming an air passage
As shown in FIG. 1B, a plain type fin can be combined to form a self-shaped meandering channel. For example, when air is supplied from the lower passage hole 7b to the upper passage hole 6b, The reduction reaction of hydrogen ions and oxygen that have permeated the polymer proceeds on the entire surface of the cathode film.
Further, as shown in FIG. 1C, it is possible to form the passage by forming the gas passage member 5 having only a single plane type fin.

As shown in FIG. 2, the gas passage members 3 and 4 are arranged on each main surface of the thin plate member 2 serving as the core member, and the thin plate members 2 are laminated with the sealing members 8 and 9 interposed therebetween, thereby separating the separator 1.
To form a cell stack, and hydrogen and oxygen can be introduced and extracted from each passage hole. Here, when the hydrogen oxidation reaction proceeds, the electrons generated are collected through the anode film of the MEA 10 and the serrate fins that are the gas passage members 3 of the separator 1 to be discharged to the outside, and the plain type of the cathode side separator is used. By connecting with the fins and the cathode film, required power generation becomes possible.

Structure 2 It is also possible to arrange the sealing members 8 and 9 independently and form a gasket as a separate member and arrange them between the separator and the MEA. More specifically, as shown in FIG. 3, the cell stack has gaskets 20 and 24 laminated on both sides of the MEA 10, and gas passage members 3 and 4 are provided in the gaskets 20 and 24, respectively.
Is arranged and the thin plate members 30 are laminated to form a separator, and a large number of cell units are laminated and arranged.

Gas passage member 3 for forming a fuel passage
Are arranged in the central hole 22b of the gasket 20 and are located at diagonal positions of the gasket 20 and are for fuel passage holes 22a, 22a.
It will communicate with c. Further, the gasket 20 is configured so as to be blocked from the air passage holes 21 and 23 located at different diagonal positions of the gasket 20.

Gas passage member 4 for forming an air passage
Are arranged in the central hole 25b of the gasket 24 and are located at diagonal positions of the gasket 24 and are provided with air passage holes 25a, 25a.
It will communicate with c. Further, the gasket 24 is configured so as to be disconnected from the fuel passage holes 26 and 27 located at different diagonal positions.

When the hydrogen oxidation reaction proceeds, the electrons generated are collected through the anode film 11 of the MEA 10 and the serrate type fin of the gas passage member 3 and led out to the cathode side plane type fin and The required power generation is possible by connecting with the cathode membrane.

In the present invention, the separator is formed by contacting a thin plate member with a fin member serving as a gas passage member. As shown in FIG. 4A, the gas passage member 3 composed of the serrated fins extends in a direction (corrugation direction of the fins) perpendicular to the undulations (ridges) of the fins between the thin plate material and the anode film of the MEA. As shown in FIG. 4B, the gas can be immediately diffused and uniformly flowed down throughout the passage member, and the hydrogen oxidation reaction proceeds on the entire surface of the anode film.

Further, the serrate type fin has an equal offset pitch cut in the fin waviness (ridge) direction as shown in FIG. 5A, and a variable pitch in which the pitch is changed as shown in FIG. 5A. It is also possible to do so. Further, when a perforate type fin is adopted instead of the serrate type fin, the pitch of the perforation positions provided in the waviness (ridge) direction can also be a variable pitch.

Further, as shown in the embodiment, the serrated fin is made of a stainless steel material having a plate thickness of 0.1 mm, the fin height which is the fuel passage height is 1 mm, the fin pitch is 3 mm, the offset is 1.5 mm, and the tunnel length is 3m
It is possible to secure a good gas flow by setting the shape and dimension to about m. Further, the fin waviness can be flattened to increase the contact area with the anode film, which can improve the uniform dispersibility of fuel gas, improve the current collecting ability, and reduce the contact resistance.

In the present invention, not only plain fins but also serrate fins, perforate type, etc. can be adopted for the gas passage member on the air passage side. However, in order to facilitate the removal of moisture generated in the passage, the corrugated Means such as providing a hydrophilic film can be adopted by selecting the direction and pitch.

According to the present invention, in the structure 1 described above, fins are arranged in contact with both sides of the partitioning thin plate material as passage members, and the sealing material is arranged on the outer peripheral portion of the thin plate material. A cell stack can be formed by alternately laminating a plurality of separators and MEAs. At this time,
When the fins are stacked, the spring effect can be exerted to reduce the contact resistance and enhance the sealing effect. Also,
In the case of the configuration 2 which employs the gasket, the same operational effect is obtained.

In the present invention, as the above-mentioned sealing material and gasket material, any known metal, alloy, ceramics, resin, or composite material thereof having a sealing function can be adopted.

[0035]

Example 1 A stainless steel material (material SUS316) having a plate thickness of 0.1 mm was used for the serrate type fin shown in FIG. 4, and the fin height as the fuel passage height was 1 mm and the fin pitch was 3 m.
m, offset 1.5 mm, tunnel length 3 mm.

Further, a plain type fin as shown in FIG. 1C is made of a stainless steel material (material SUS3 having a thickness of 0.1 mm).
16) is used, the fin height that is the height of the air passage is 1
mm and fin pitch 3 mm.

As shown in FIG. 1, the partition thin plate material is press-punched and molded by using a stainless steel material (material SUS316) having a thickness of 0.1 mm, and the fins are arranged by using a ceramic having a thickness of 1 mm as a sealing material. A separator according to the invention was made.

A perfluorosulfonic acid-based polymer is adopted for the polymer film, and MEA in which a thin film obtained by screen-printing a Pt-based catalyst and an electrolyte polymer on carbon paper is pressure-bonded to the polymer film and the separator are alternately laminated. Arranged and assembled the cell stack which consists of 10 cells.

The size of the obtained cell stack is 100 mm.
X 100 mm x 200 mm, hydrogen gas supply amount 5
The output was 6 V and 40 A under the condition of 00 Nl / hr.

Example 2 The same material and size as in Example 1 were used for the serrate type fin and the plain type fin, and the same MEA and partitioning thin plate material as in Example 1 were used to obtain the structure shown in FIG. A cell stack consisting of 10 cells was assembled.

The size of the obtained cell stack was the same as that of Example 1, the same amount of hydrogen gas was supplied, and the same 240 WC was obtained.
An output of J / s was obtained.

[0042]

According to the present invention, the separator has a simple structure in which the partition thin plate material and the super flat fins such as serrated fins are simply combined, and the fuel gas is directed in the direction perpendicular to the waviness of the fins in the passage. It is possible to remarkably improve the dispersibility of the passing fluid without increasing the passing resistance.

Further, according to the present invention, the separator can be made of a metal material such as stainless steel, and the super flat serrate type fins of the same material can perform stable current collection with low resistance and high cell performance. It becomes possible to achieve both stability. Further, there is an advantage that the metal plate material can be easily manufactured only by pressing or punching.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the structure of a separator according to the present invention, in which A is a fuel passage and B and C are air passages.

FIG. 2 is an explanatory view showing a structure of gas supply holes of a separator according to the present invention, where A is a stack and B and C are partition thin plate materials.

FIG. 3 is an exploded perspective view showing another configuration of the fuel cell according to the present invention.

FIG. 4A is a perspective explanatory view showing a configuration example of a passage member of the separator according to the present invention, and B is a schematic explanatory view showing a gas flow in the passage member.

FIG. 5A and FIG. 5B are perspective explanatory views showing offset pitches of serrated fins.

[Explanation of symbols]

1 Separator 2, 30 Thin Plate Material 3, 4, 5 Gas Passage Member 6a, 6b, 7a, 7b, 21, 22a, 22c, 23
Passage holes 8 and 9 Sealing material 10 MEA 11 Anode films 20 and 24 Gaskets 22b and 25b Central hole

Claims (6)

[Claims] 1. A direction (corrugation direction of fins) perpendicular to the undulations (ridges) of a fin, where a serate fin or a perforate fin having a fin height of 2 mm or less is brought into contact with a thin plate material as a gas passage member. A fuel cell having a separator configured to allow gas to flow through. 2. The variable pitch is the pitch of the offset cut in the waviness (ridge) direction of the serrate type fin or the pitch of the perforation positions provided in the waviness (ridge) direction of the perforate type fin. Fuel cell. 3. The fuel cell according to claim 1, wherein a conductive thin film is formed on at least the fin tops. 4. The fuel cell according to claim 3, wherein a conductive thin film is formed at least at a position in contact with the fin tops of the thin plate material. 5. The fuel cell according to claim 1, wherein the fin height of the gas passage member is 1 mm or less and the plate thickness is 0.1 mm or less. 6. The fuel cell according to claim 1, wherein the gas passage member and the thin plate member are made of a stainless steel material.