JPH11339823A - Solid polymer electrolyte fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive gas flow plate (separator) capable of increasing electric conductivity, by using a conductive resin material containing copper powder, capable of injection molding, simplifying a working process, and reducing a production cost. SOLUTION: In a solid polymer electrolyte fuel cell in which electrodes are arranged on both sides of a solid polymer electrolyte film, and having a gas flow plate 11a in which gas flow grooves through which fuel gas is supplied to one side of the electrode and an oxidizing agent gas is supplied to the other side of the electrode are formed, the gas flow plate 11a is made of a conductive resin material containing copper powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art Various types of fuel cells, such as a solid polymer electrolyte type, a phosphoric acid type, a molten carbonate type, and a solid oxide type, are known depending on the type of electrolyte used. Among them, the solid polymer electrolyte fuel cell is a fuel cell utilizing the fact that a polymer electrolyte membrane having a proton exchange group in a molecule functions as a proton conductive electrolyte when saturated with water, and has a relatively low temperature. It operates in a wide range and has excellent power generation efficiency, and is expected to be used in various applications, including those used in electric vehicles.

In a polymer electrolyte fuel cell, a plurality of unit cells (unit cells) for generating electric power by an electrochemical reaction are stacked,
By holding it under pressure, a battery (stack) is formed. The unit cell is composed of a polymer electrolyte membrane, an anode (fuel electrode) and a cathode (oxidant electrode) joined to both sides thereof. For stacking, a member called a separator is provided between each unit cell. The separator is provided with a gas flow groove through which oxygen or hydrogen flows.

In a polymer electrolyte fuel cell, a mixed gas of hydrogen, carbon dioxide, nitrogen and water vapor is supplied to an anode side, and air and water vapor are supplied to a cathode side.

In a polymer electrolyte fuel cell, in order to maintain the ion conductivity of the polymer electrolyte membrane (ion exchange membrane), it is necessary to maintain the polymer electrolyte membrane in a water-containing state. It is necessary to contain water vapor in the fuel hydrogen gas and oxygen serving as the oxidizing agent. For this reason,
Depending on the operating temperature conditions, a phenomenon occurs in which steam reaches the dew point in the gas passages of the separator and becomes water droplets, closing the gas passages and inhibiting the characteristics of the fuel cell.

To cope with this, US Pat.
No. 0,370 discloses a structure in which a gas flow path of a separator is turned up to increase the gas flow rate so that water that has become water droplets can always be discharged from the battery.

[0007]

As a material for the separator, dense carbon, which is excellent in electric conductivity and resistant to corrosion, is generally used, the material itself requires a large amount of energy, so that the cost is high and the cost is extremely high. Fragile. However, since US Pat. No. 5,300,370 discloses a folded structure in which gas flow grooves are formed in the entire separator, the processing of the grooves of the separator requires a large amount of processing time and increases the production cost. I will.

The present invention has solved the above-mentioned problems. Since the present invention is a conductive resin material containing copper powder, the electric conductivity is improved, and processing by injection molding or the like becomes possible.
Provided is a solid polymer electrolyte fuel cell having an effect of simplifying a processing step, reducing production costs, and having an inexpensive gas passage plate (separator).

[0009]

Means for Solving the Problems In order to solve the above technical problems, the technical means (hereinafter referred to as first technical means) taken in claim 1 of the present invention is a solid polymer electrolyte. An electrode is disposed on both sides of the membrane, a fuel gas is supplied to one side of the electrode, and a gas passage plate having a flow groove for supplying an oxidizing gas is provided on the other side of the electrode. In a polymer electrolyte fuel cell, the gas passage plate is formed of a conductive resin material mixed with copper powder.

The effects of the first technical means are as follows.

That is, since it is a conductive resin material containing copper powder, the electric conductivity is good, and processing by injection molding or the like becomes possible, the processing steps are simple, the production cost can be reduced, and the cost is low. This has the effect of having a gas passage plate (separator).

[0012] In order to solve the above technical problem, the technical means (hereinafter referred to as second technical means) taken in claim 2 of the present invention is a method of transferring copper powder to the conductive resin material. The mixed amount is 30% by volume or more, and the volume specific resistance thereof is 10 ⁻³ Ωcm or less.
20 is a solid polymer electrolyte fuel cell according to the above.

The effects of the second technical means are as follows.

That is, if the amount of copper powder mixed into the conductive resin material is 30% by volume or more, the volume resistivity of the conductive resin material becomes 10 ⁻³ Ωcm or less, and the solid polymer electrolyte fuel cell It has a sufficient conductivity effect as a gas passage plate. If the amount of the copper powder mixed into the conductive resin material is less than 30% by volume, the volume specific resistance value increases, and a sufficient conductive effect as a gas passage plate of a solid polymer electrolyte fuel cell cannot be obtained.

In order to solve the above technical problem, the technical means (hereinafter referred to as third technical means) taken in claim 3 of the present invention is a conductive resin into which the copper powder is mixed. 2. The solid polymer electrolyte fuel cell according to claim 1, wherein the material is a thermoplastic resin material such as polypropylene or nylon.

The effects of the third technical means are as follows.

That is, since it is obtained from a thermoplastic resin material such as general-purpose polypropylene, nylon, or polybutylene terephthalate, it can be obtained at a low cost.

In order to solve the above technical problem, the technical means (hereinafter referred to as fourth technical means) taken in claim 4 of the present invention is that the conductive resin material is formed by injection molding or compression. The polymer electrolyte fuel cell according to claim 1, wherein the fuel cell is formed by molding.

The effects of the fourth technical means are as follows.

That is, general-purpose injection molding equipment and compression molding equipment can be used, and these apparatuses can be easily mass-produced from a metal mold, so that they can be molded cheaper and faster than conventional carbon graphite.

In order to solve the above technical problem, the technical means (hereinafter referred to as a fifth technical means) taken in claim 5 of the present invention is the gas passage made of the conductive resin material. 2. The polymer electrolyte fuel cell according to claim 1, wherein the surface of the plate is surface-treated by plating or sputtering of a noble metal material.

The effects of the fifth technical means are as follows.

That is, in addition to the first aspect, the electric conductivity can be further improved. In addition, corrosion can be prevented.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings.

FIG. 1 is an exploded view of each member of the solid polymer electrolyte fuel cell of the present invention.

As shown in FIG. 1, the gas passage plates 11a and 11b are respectively pressed against the surfaces of the electrodes 2a and 2b joined to the solid polymer electrolyte membrane 1 so as to sandwich the solid polymer electrolyte membrane 1. Things.

The gas passage plates 11a and 11b have flow grooves 6a and 6b for supplying fuel gas or oxidizing gas on one surface facing the respective electrode sides 2a and 2b.
The other surface sides 6ah and 6bh of the gas passage plates 11a and 11b (the other side from the electrodes 2a and 2b) are substantially flat surfaces. The outer peripheral edge 11ae of this gas passage plate 11, 1
1be is provided with seal members 5a and 5b. Further, a metal plate 3 having the same outer shape as the seal members 5a, 5b is provided on the substantially flat surface side of the gas passage plates 11a, 11b.
a, 3b are provided.

Further, a cooling plate 7 is arranged further behind (upper part in FIG. 1) than the metal flat plates 3a and 3b. In FIG. 1, a gas passage plate, a seal member, and a metal flat plate above the cooling plate 7 are vertically symmetrical with respect to the cooling plate 7 (FIG. 1), and thus detailed description is omitted. The cooling plate 7 has the same structure as the gas passage plate 11 and the sealing member 5a.

The seal member 5a has a rectangular shape as shown in FIG. 2, and has a rectangular void 5ak so that the gas passage plate 11a can be disposed inside. The seal member 5a has an oxidizing gas supply passage 5aa, a cooling water supply passage 5ab, and a fuel gas supply passage 5ac. Further, as shown in the lower part of FIG.
a ', cooling water discharge passage port 5ab', fuel gas discharge port 5a
c 'is formed.

FIG. 3 is a sectional view taken along line AA of the seal member 5a of FIG.

A seal holding metal plate 5ad having a thickness of about 0.1 mm is buried inside the seal member 5,
a is ensured. The sealing member is shown in FIG.
(See B in FIG. 2), an oxidant supply member 5af in which four oxidant gas supply passage grooves 5ae are engraved is embedded. An oxidant supply member 5a in which four fuel gas outlets 5ae 'are engraved also in a lower portion of FIG.
f 'is buried.

FIG. 5 is a plan view of the metal flat plate 3a. The metal flat plate 3a has an oxidizing gas supply passage 3aa, a cooling water supply passage 3ab, and a fuel gas supply passage 3ac. Similarly, an oxidizing gas discharge passage 3aa ', a cooling water discharge passage 3ab', and a fuel gas discharge 3ac 'are formed in the lower part of FIG. This metal plate is about 3mm
It is a plate of about the thickness.

As shown in FIG. 1, the solid polymer electrolyte membrane 1, a pair of gas diffusion electrodes 2a and 2b, and a gas passage plate 1
1a, 11b, sealing members 5a, 5b, metal plates 3a, 3
b and the cooling plate 7 constitute one cell.

FIG. 6 is a plan view (left side) of the gas distribution plate 11a.
And a sectional view taken along the line BB of this plan view (right side). The gas flow plate 11a has a plurality of grooves 6a formed therein. In the flow groove 6a, the inlet-side flow groove 6aa directly communicating with the oxidizing gas supply passage port 5aa is formed in a lattice shape, and the intermediate flow groove 6ab is formed in a bent shape in which a plurality of diffractions are performed. , And a lattice-shaped groove 6ac formed in the folded portion. In other words, the inlet-side flow grooves 6aa and the outlet-side flow grooves 6ad have gas flow grooves in regions other than the isolated protrusions K1 formed in a matrix, and the independent passage group 6aa has gas flow grooves in regions other than the elongated protrusions K2. It is a groove. Also, the lattice-shaped groove 6 at the folded portion
In ac, a region other than the isolated protrusion K3 is a gas flow groove.

As described above, the oxidizing gas supply passage opening 3aa
One of the supply gases from enters the inlet-side circulation groove 6aa.
This is because the inlet side flow groove 6aa is a lattice groove, and the supply gas freely moves in the lattice groove by the original pressure of the gas supply device and comes into contact with the electrode in a short time.

In the intermediate flow groove 6ab, the independent passage group 6aa
The main component is to distribute gas at high speed and evenly to improve gas use efficiency, and reduce the pressure loss by using a plurality of gas passages. In the folded portion 6ac, the flow path resistance in the independent passage group 6aa is further reduced, and the independent passage group 6aa
This has the effect of maintaining gas diffusivity at the surface.

In the outlet side flow groove 6ab, the stagnant water is drained by the gas having a high flow rate from the final independent passage group 6ab.

FIG. 7 is an assembled view of the gas passage plate 11a of FIG. 6, the sealing member 5a of FIG. 3, and the metal flat plate 3a of FIG.

As shown in FIG. 7, the oxidant gas passage plate 1
The outer shape of 1a is located inside the oxidizing gas supply passage 5aa and the oxidizing gas discharge passage 5aa 'formed in the seal member 5a and the metal flat plate 3a, and is disposed inside the frame-shaped seal member 5a. doing.

Next, the oxidizing gas flows from the oxidizing agent supply passage 5aa, and is led out from the oxidizing gas discharge port 5aa 'through the flow groove 6a.

Similarly, the fuel gas flows into the gas passage plate 11b of the fuel gas from the fuel gas supply passage 5ac.
Through the flow groove 6b, the fuel gas is supplied to the fuel gas outlet 5ac '.
Derived from

In FIG. 6, the gas passage plate 11a is formed by adding copper powder having a particle size of about 5 μm to polypropylene or nylon,
Or PBT (polybutene terephthalate) -AB
A conductive resin material is prepared by mixing 45 vol% with the S alloy resin material. Thereafter, the gas passage plate 11ae is formed from the conductive resin material by an injection molding method or a compression molding method. In addition, low melting point alloy Sn-4Cu-2Ni-
Also, 45 vol% of 0.3P is mixed. The obtained conductive resin had a volume resistivity of 10 ⁻⁴ Ωcm or less.

FIG. 12 is a diagram showing the relationship between the amount of copper powder mixed into the polypropylene resin and the volume resistivity.

Further, the surface of the gas passage plate 11a made of a conductive resin material is plated with a noble metal such as gold, platinum, palladium or the like for improving electric conductivity and preventing corrosion, or subjected to a surface treatment such as sputtering. I am giving.

The sealing member 5a disposed on the outer peripheral edge of the gas passage plate 11a is formed of the same conductive resin material as that of the gas passage plate 11a or a rubber made of fluororesin or EPDM (ethylene-propylene rubber). May be.

The gas passage plate 11a may be formed by compression molding a conductive resin material to form grooves as shown in FIG.
The left diagram in FIG. 8 is a plan view of the gas passage plate 11a, and the right diagram is a cross-sectional view taken along line CC of the left diagram.

Further, a conductive resin or a metal surface which is a material of the gas passage plate is plated with a noble metal such as gold, platinum, palladium or the like for improving electric conductivity and preventing corrosion, or subjected to a surface treatment such as a sputtering process. You may.
This plating treatment is performed by a conventional electrolytic plating method or an electroless plating method to a thickness of 10 μm.

As shown in FIGS. 9 to 11, the gas passage plate 111a is divided into two members as shown in FIGS. That is, as shown in FIG. 9, the gas passage plate 111a is used as an outer peripheral member 112a, and the outer peripheral member 112a is formed of a conductive resin. Further, as shown in FIG. To form a groove. The outer peripheral portion 112a forms a lattice-shaped protrusion made of a conductive resin, and forms the bent portion shown in FIG. Thereby, moldability is easy and assemblability can be improved. 9 is the gas passage plate 1.
It is a top view of the outer peripheral member 112a of 11a, and the right figure is the DD sectional view taken on the line. 10 is a plan view of the inner member 113a of the gas passage plate 111a, and the right figure is a cross-sectional view taken along line EE.

In the present invention, the sealing member is provided around the outer frame edge of the gas passage plate and the gas passage plate and the metal plate are used. The gas passage plate may be formed of a conductive resin material mixed with copper powder.

[0050]

As described above, according to the present invention, the electrodes are arranged on both sides of the solid polymer electrolyte membrane, the fuel gas is supplied to one side of the electrodes, and the oxidized surface is supplied to the other side of the electrodes. A solid polymer electrolyte fuel cell having a gas passage plate provided with a flow groove for supplying an agent gas, wherein the gas passage plate is formed of a conductive resin material mixed with copper powder. Because it is a solid polymer electrolyte type fuel cell, it is a conductive resin material containing copper powder, so it has good electrical conductivity, and it can be processed by injection molding and the like, and the processing process is simple. This has the effect of reducing production costs and having the effect of having an inexpensive gas passage plate (separator).

[Brief description of the drawings]

FIG. 1 is an exploded sectional view of a unit cell according to an embodiment of the present invention.

FIG. 2 is a plan view of a sealing member.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a view as viewed from B in FIG. 2;

FIG. 5 is a plan view of a flat metal plate.

FIG. 6 is a plan view of the gas passage plate and a cross-sectional view taken along line BB.

FIG. 7 is a plan view in which a gas passage plate, a seal member, and a metal flat plate are assembled.

FIG. 8 is a plan view in which a flow groove is formed by press-molding a metal plate and a cross-sectional view taken along line CC.

FIG. 9 is a plan view of an outer peripheral member of the gas passage plate and a cross-sectional view taken along line DD.

FIG. 10 is a plan view and a cross-sectional view taken along line EE of an inner member of the gas passage plate.

FIG. 11 is a plan view of a gas passage plate in which an outer peripheral member and an inner member are assembled.

FIG. 12 is a diagram showing a relationship between mixing of copper powder into a resin material and volume resistivity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Solid polymer electrolyte membrane 2a, 2b ... Electrode 3a, 3b ... Metal flat plate 5a, 5b ... Seal member 6a, 6b ... Flow groove 11a, 11b ... Gas passage plate 11ae, 11be ... Peripheral edge

Claims (5)

[Claims] An electrode is disposed on both sides of a solid polymer electrolyte membrane, and a flow groove for supplying a fuel gas to one side of the electrode and supplying an oxidizing gas to the other side of the electrode is formed. A solid polymer electrolyte fuel cell having a gas passage plate, wherein the gas passage plate is formed of a conductive resin material mixed with copper powder. battery. 2. The method according to claim 1, wherein the amount of the copper powder mixed into the conductive resin material is 30% by volume or more, and the volume specific resistance of the conductive resin material is 10 ⁻³ Ωcm or less. 2. The solid polymer electrolyte fuel cell according to 1. 3. The solid polymer electrolyte fuel according to claim 1, wherein the conductive resin material into which the copper powder is mixed is a thermoplastic resin material such as polypropylene, nylon, or polybutylene terephthalate. battery. 4. The polymer electrolyte fuel cell according to claim 1, wherein the conductive resin material is formed by injection molding or compression molding. 5. The polymer electrolyte type according to claim 1, wherein the surface of the gas passage plate made of the conductive resin material is subjected to a surface treatment by plating or sputter processing made of a noble metal material. Fuel cell.