JPH08222237A - Separator for fuel cell - Google Patents

Abstract

PURPOSE: To provide a new structure of a separator for a fuel cell whose cost is reduced and which is excellent in productivity and whose safety is enhanced and which is excellent in supply efficiency of reaction gas. CONSTITUTION: In a fuel cell stack formed by layering a plurality of cells 10 where electrodes 12 are arranged on both sides of solid electrolyte 11, it is used by being interposed between these cells. The obverse and the reverse of a metallic material excellent in workability are coated with a material excellent in electric conductivity, and a large number of projections 21 and 22 are arranged at proper intervals on these obverse and reverse. The projections are arranged so as to contact with cell surfaces of the fuel cell in the fuel cell stack. A space area 38 communicated and formed between the projections 21 between one side surface of a separator and the cells of the fuel cell becomes a fuel gas passing groove, and a space area communicated and formed between the projections 22 between the other side surface of the separator and the cells of the fuel cell becomes an oxidating agent gas passage groove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a fuel cell separator.

[0002]

2. Description of the Related Art Fuel cells, depending on the type of electrolyte used, are solid polymer electrolyte type, phosphoric acid type, molten carbonate type,
Various types such as solid oxide type are known. Among them, the solid polymer electrolyte fuel cell is a fuel cell that utilizes a polymer resin membrane having a proton exchange group in the molecule to function as a proton-conducting electrolyte when saturated with water, and has a relatively low temperature. Since it operates in the region and has excellent power generation efficiency, it is expected to be used for various purposes including mounting on electric vehicles.

The solid polymer electrolyte fuel cell stack is
Fuel cell (single cell) in which gas diffusion electrodes are bonded to both sides of a solid polymer electrolyte membrane by means such as hot pressing
And a gas separator made of carbon or metal are laminated (see, for example, Japanese Patent Laid-Open No. 6-119928).

The gas diffusion electrode supports a catalyst layer containing a catalyst active material disposed on the side in contact with the electrolyte membrane, supports the catalyst layer, and supplies and discharges a reaction gas (fuel gas, oxidant gas). It is composed of a porous gas diffusion layer which also has a function as a current collector, and one gas diffusion electrode is a fuel gas (for example, hydrogen gas or a gas containing hydrogen at a high concentration).
Is supplied to the fuel electrode (anode electrode), and the other gas diffusion electrode serves as an oxidant electrode (cathode electrode) supplied with an oxidant gas (for example, air).

An example of the structure of such a two-cell fuel cell stack according to the prior art is shown in FIGS.

The unit cell 10 is composed of the electrolyte membrane 1 as described above.
The gas diffusion electrodes 12 are bonded to both surfaces of No. 1.

In the separator, the separator plate 1 made of a gas impermeable material (for example, dense carbon graphite) having a large number of recessed grooves 2 and 3 formed in the front and back surfaces in a direction orthogonal to each other is a resin insulating material such as phenol resin. It is configured to be supported while being housed inside a separator frame 4 made of. Manifold loading ports 5a to 5d for accommodating a gas manifold are formed in the separator frame 4.

In the fuel cell stack in which the separator and the unit cell 10 are laminated, the fuel gas is introduced into the gas manifold (not shown) loaded in the manifold loading port 5a and the inside of the separator frame 4 is introduced. The separator plate 1 is inserted through the flow path hole 6a formed inside the frame portion 8a.
Is introduced into the upper space region 7a between the separator frame 4 and the separator frame 4, and flows in the concave groove 2 on the front surface side of the separator plate 1 in the left direction in FIG. Then, via a flow path hole (not shown) formed inside the inner frame portion 8c facing the inner frame portion 8a,
The fuel gas is discharged to a fuel gas discharge manifold (not shown) loaded in the manifold loading port 5b.

The flow of the oxidant gas is substantially the same, and the oxidant gas introduced into the gas manifold portion 5c passes through the flow path hole 6b formed inside the inner frame portion 8c of the separator frame 4, After being introduced into the lower space region 7b between the separator plate 1 and the separator frame 4 and flowing leftward in the concave groove 3 on the back surface side of the separator plate 1 in FIG. 7, the inside of the inner frame portion 8d of the separator frame 4 It is discharged to an oxidant gas discharge manifold (not shown) loaded in the manifold loading port 5d through a flow path hole (not shown) formed in the.

[0010]

In the conventional separator as shown in FIGS. 5 to 7, a large number of concave grooves 2 and 3 to be gas flow channels must be formed on the front and back surfaces thereof. Since the hardness of the dense carbon graphite of the separator material is extremely high, there is a problem that the cutting process is not easy even with a cutting tool such as a diamond tool and mass production is difficult.

Further, especially in the oxidant electrode, it is necessary to efficiently discharge the water generated by the cell reaction, but the gas passage grooves of the conventional separator are a plurality of parallel grooves, and the generated water tends to stay. It was lacking in discharge efficiency. If the discharge efficiency of the generated water is poor, it may cause the electrode to peel off from the electrolyte membrane, and there is a risk that the reaction gas reacts with the catalyst on the electrode and ignites at the end of the electrode.

[0012]

Therefore, the present invention solves the above-mentioned problems of the prior art, and is novel with low cost, good productivity, high safety, and excellent reaction gas supply efficiency. An object of the present invention is to provide a structure of a fuel cell separator.

Another object of the present invention is also to reduce the size of the separator and thus reduce the size and weight of the fuel cell stack.

To achieve these objects, the present invention provides
Used in a fuel cell stack in which a plurality of fuel cells having electrodes arranged on both sides of a solid electrolyte are stacked, and used by being inserted between the fuel cells, and one fuel cell is fueled to one fuel cell adjacent to one side. A fuel cell separator having a fuel gas flow channel for supplying gas, and an oxidant gas flow channel for supplying an oxidant gas to the other fuel cell adjacent to the other side surface. Therefore, the front and back surfaces of a metal material excellent in workability are coated with a material having excellent electrical conductivity, and a large number of projections are provided on the front and back surfaces at appropriate intervals. The fuel cell stack is provided so as to be in contact with the fuel cell surface, and the fuel gas flow channel and the oxidant gas flow channel are respectively the separator and the fuel cell. Characterized in that it is communicating formed between the projection between.

[0015]

The fuel gas supplied from the gas manifold loaded in the fuel gas supply gas manifold charging port formed in the separator has a surface of the separator between the separator and the fuel cell on one side of the separator. It is discharged through a fuel gas passage groove formed so as to communicate between the protrusions into a gas manifold that is also installed in the opening-forming fuel gas discharge gas manifold charging port on the opposite side of the separator. On the other side of the separator, the oxidant gas similarly flows from the oxidant supply gas manifold into the oxidant exhaust gas manifold through the oxidant gas flow channel groove formed to communicate between the protrusions on the separator surface. Is discharged.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a fuel cell separator according to an embodiment of the present invention will be described below with reference to FIGS.

This separator includes a separator plate 20 and
The separator frame 30 is formed by joining a pair of separator frame members 30a and 30b made of a resin insulating material such as phenol resin. The separator plate 20 is sandwiched and fixed between the separator frame members 30a and 30b.

Referring to FIG. 1, the separator plate 20 is made of a metal material that is easily embossed or dimpled, more specifically, SUS, cold rolled material, Al, etc.
A gas impermeable material with good electric conductivity on the front and back surfaces, for example, impregnated with dense carbon graphite, thermal spraying, electrodeposition,
The coating is carried out by an appropriate technique such as sputtering, and then embossing or dimple processing is applied to form a large number of projections 21 and 22 on the front and back surfaces thereof at intervals of several millimeters. The heights of the protrusions 21 and 22 to the tops are set so that the tops of the protrusions are in close contact with the fuel cell unit cell 10 when the fuel cell stack is constructed (FIG. 3).

The gas impermeable material may be coated on the front and back surfaces of the substrate and then embossed or dimpled. Conversely, the front and back surfaces of the substrate may be embossed or dimpled to form the protrusions 21 and 22. After that, the gas impermeable material may be coated.

Manifold loading ports 23 for loading a gas manifold are formed through the outer four rims of the regions where the protrusions 21 and 22 are formed. Further, a through hole 24 for penetrating a bolt or a tie rod for fixing the stack is formed through the square.

The separator frame 30 is formed by joining separator frame members 30a and 30b having the same structure. A sealant is applied to each joint in advance.

The structure of the separator frame member 30a (30b) is shown in FIG. An opening 31 is formed through the center of the separator frame member 30a. Manifold loading ports 32 for loading the gas manifolds are formed through the four outer circumferences of the central opening 31, and through holes 33 for passing the stack fixing bolts or tie rods are formed in the squares. These are provided so as to be aligned with the manifold loading port 23 and the through hole 24 in the separator plate 20, respectively.

On the lower surface side of the separator frame member 30a, a large number of gas passage holes 34 are provided so as to face each other. These gas flow passage holes 34 are open at the manifold loading ports 32, 32 and the central opening 31, respectively, at both ends thereof.

The separator frame members 30a and 30b configured as described above are turned 90 degrees to be orthogonal to each other, and the upper surfaces shown in FIG. 2 are faced to each other, and the separator frame members 30a and 30b are placed between them. The separator of this embodiment is constructed by sandwiching the separator plates 20 and joining them together.

FIG. 3 shows a unidirectional sectional view of a case where a two-cell fuel cell stack is constructed by sandwiching two single cells 10, 10 between the separators using such a separator. Each fuel cell unit cell 10 is formed by joining gas diffusion electrodes 12, 12 to both sides of a solid polymer electrolyte membrane 11 by means such as hot pressing. Between the separators, the end portion of the electrolyte membrane 11 in the fuel cell unit cell 10 is sandwiched between the separator frame members 30a and 30b, and is adhesively fixed by a sealant 36 made of a thermosetting resin such as epoxy resin.

In FIG. 3, reference numeral 37 indicates a loading area for a fuel gas introduction manifold (not shown), and each of the manifold loading ports 23, 32 formed in the separator plate 20 and the separator frame members 30a, 30b. One is aligned to form the manifold loading area 37. The fuel gas introduced into the fuel gas introduction manifold is supplied from the manifold loading port 37 to the upper separator frame member 30a.
Through the gas passage hole 34 provided on the lower surface side of
Between the upper surface of the separator plate 20 and the lower surface of the unit cell 10, a flow is made in the arrow direction through a space region 38 formed continuously between a large number of protrusions 21 formed on the upper surface of the separator plate, and the manifold on the opposite side. The fuel gas is discharged to a fuel gas discharge manifold (not shown) loaded in the loading port.

FIG. 4 is a sectional view of the fuel cell stack in a direction orthogonal to FIG. Reference numeral 39 in FIG.
Shows a loading area for an oxidant gas introduction manifold (not shown). The oxidant gas introduced into the oxidant gas introduction manifold passes from the manifold loading port 39 through the gas passage hole 35 provided on the upper surface side of the lower separator frame member 30b, and further, the separator plate 20 and the unit cell 10 are connected.
Through a space region 40 formed continuously between the plurality of projections 22 and in the direction of the arrow, and is discharged to an oxidant gas discharge manifold (not shown) loaded in the manifold loading port on the opposite side. To be done.

[0028]

According to the present invention, a metal material which is easily embossed or dimpled and coated with a gas impermeable material having excellent electric conductivity is used as a separator. Since many protrusions are formed by processing or dimple processing to form the reaction gas flow channel groove, the reaction gas flow channel groove can be easily processed and the separator can be mass-produced at low cost.

Further, the reaction gas supply efficiency is improved by the turbulent flow effect which was not obtained in the conventional reaction gas flow passage groove formed of parallel grooves, and the retention of the produced water at the oxidizer electrode can be eliminated.

Furthermore, according to the present invention, it is possible to reduce the thickness of the conventional dense carbon graphite separator of 5.3 mm to about 0.5 mm. Therefore, in a fuel cell stack in which a large number of fuel cells and separators are stacked, a significant reduction in size and weight is realized.

[Brief description of drawings]

FIG. 1 is a top view of a separator plate used in a fuel cell separator according to an embodiment of the present invention.

FIG. 2 is a top view of a separator frame member.

3 is a cross-sectional view showing a 2-cell fuel cell stack obtained by using a separator configured by sandwiching the separator plate of FIG. 1 between the separator frame members of FIG. 2 from above and below.

4 is a cross-sectional view of the two-cell fuel cell stack of FIG. 3 viewed from a direction orthogonal to FIG.

FIG. 5 is a top view of a 2-cell fuel cell stack according to the prior art.

6 is a cross-sectional view taken along the line AA in FIG.

FIG. 7 is a sectional view taken along line BB in FIG.

[Explanation of symbols]

 10 Fuel Cell Single Cell 20 Separator Plate 21, 22 Protrusion 30 Separator Frame 30a, 30b Separator Frame Member 23, 32 Gas Manifold Loading Port 34 Fuel Gas Channel Hole 35 Oxidant Gas Channel Hole 37 Fuel Gas Introduction Manifold Loading Area 38 Fuel Gas channel 39 Oxidizing gas introduction manifold loading area 40 Oxidizing gas channel

Claims (2)

[Claims] 1. A fuel cell stack in which a plurality of fuel cells having electrodes arranged on both sides of a solid electrolyte are stacked and used by being inserted between the fuel cells, and one side surface of one of the adjacent fuel cells is used. A fuel gas flow channel for supplying a fuel gas to the fuel cell was provided, and an oxidant gas flow channel for supplying an oxidant gas to the other adjacent fuel cell was provided on the other side surface. A fuel cell separator, in which the front and back surfaces of a metal material with excellent workability are coated with a material with excellent electrical conductivity, and a large number of protrusions are provided on the front and back surfaces at appropriate intervals. The protrusion is provided so as to be in contact with the fuel cell surface in the fuel cell stack, and the fuel gas flow channel and the oxidant gas flow channel are respectively provided in the fuel cell stack and the fuel cell stack. A fuel cell separator, characterized in that the fuel cell separator is formed so as to communicate with the fuel cell. 2. The separator frame is composed of two separator frame members divided into two in the thickness direction, and a peripheral edge portion of the separator plate is sandwiched between the separator frame members and integrally joined. Claim 1 characterized by the above-mentioned.
Fuel cell separator.