JP2008181785A - Fuel cell, and manufacturing method of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To seal the peripheral edge part of a cathode side metal plate and the peripheral edge part of an anode side metal plate while carrying out downsizing of the cathode side metal plate and the anode side metal plate in a fuel cell. <P>SOLUTION: At first, a membrane electrode assembly unit 50 in which a gasket is arranged surrounding the membrane electrode assembly, cathode side metal plate 60c, and anode side metal plate 60a of a membrane electrode assembly are manufactured (step S 100, 110). Then, on the surface of cathode side gas diffusion layer 30c of the membrane electrode assembly 52, a metal porous body 40c is arranged, on the surface of anode side gas diffusion layer 30a, a metal porous body 40a is arranged, and furthermore, to these respective surfaces, the cathode side metal plate 60c and the anode side metal plate 60a are respectively made contacted (step S 120). Then, the peripheral part 60e of the cathode side metal plate 60c and the peripheral part 60e of the anode side metal plate 60a are joined by laser welding, and sealed (step S 130). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell and a method for manufacturing the fuel cell.

  A fuel cell that generates electricity by an electrochemical reaction between hydrogen (fuel gas) and oxygen (oxidant gas) has attracted attention as an energy source. In this fuel cell, a membrane electrode assembly formed by joining an anode and a cathode to both surfaces of an electrolyte membrane having proton conductivity is separated by a separator (for example, an anode side metal plate and a cathode side metal plate). It is configured by pinching.

  Various structures have been proposed for this fuel cell. For example, in the following Patent Documents 1 and 2, a plate-shaped solid polymer electrolyte, a cathode-side electrode plate disposed on one side of the solid polymer electrolyte, an anode-side electrode plate disposed on the other side, A cathode-side metal plate that is disposed on the surface of the cathode-side electrode plate and allows gas to flow to the inner surface side, and an anode-side metal plate that is disposed on the surface of the anode-side electrode plate and allows fuel to flow to the inner surface side And a peripheral portion of the cathode side metal plate and a peripheral portion of the anode side metal plate are electrically insulated and sealed with caulking.

JP 2006-92783 A JP 2006-92842 A

  However, in the techniques described in Patent Documents 1 and 2, since the peripheral portion of the cathode side metal plate and the peripheral portion of the anode side metal plate are sealed by “caulking”, the cathode side metal plate, and The anode side metal plate requires a region for “caulking”, and the size of the cathode side metal plate and the anode side metal plate has to be relatively large.

  The present invention has been made to solve the above-described problems. In a fuel cell, the cathode-side metal plate and the anode-side metal plate are reduced in size while the cathode-side metal plate has a peripheral portion and an anode. It aims at sealing the peripheral part of a side metal plate.

  In order to solve at least a part of the above-described problems, the present invention employs the following configuration. That is, the fuel cell of the present invention has a membrane electrode assembly formed by joining an anode and a cathode on both surfaces of the electrolyte membrane, and a fuel gas supply port for supplying fuel gas to the anode, An anode-side metal plate that contacts the anode; and a cathode-side metal plate that has an oxidant gas supply port for supplying an oxidant gas to the cathode and contacts the cathode. And the cathode metal plate are joined to each other by welding, and the anode metal plate or the cathode metal plate electrically insulates the anode and the cathode from each other. The gist is to provide an insulating structure.

  In the present invention, the peripheral edge of the anode-side metal plate and the peripheral edge of the cathode-side metal plate are joined by welding. Therefore, the “caulking” is provided on the peripheral edge of the anode-side metal plate and the peripheral edge of the cathode-side metal plate. It is not necessary to provide an area for performing "." Therefore, it is possible to seal the peripheral portion of the anode side metal plate and the peripheral portion of the cathode side metal plate while reducing the size of the cathode side metal plate and the anode side metal plate. In addition, as welding, laser welding etc. are mentioned, for example. In the present invention, since the anode side metal plate or the cathode side metal plate has an insulating structure, electrical insulation between the anode and the cathode can be ensured. Further, when the peripheral portion of the cathode side metal plate and the peripheral portion of the anode side metal plate are sealed by “caulking”, there is a risk that mechanical damage may be applied to the cathode and the anode. This fear can be eliminated by the present invention.

  In the fuel cell, the anode-side metal plate or the cathode-side metal plate has, as the insulating structure, a first metal member that contacts the anode or the cathode, and the first metal member. And an insulating member bonded to the periphery of the insulating member, and a second metal member bonded to the periphery of the insulating member.

  In the present invention, the first metal member contacts the anode or cathode of the membrane electrode assembly, but the second metal member does not contact the anode or cathode. An insulating member is disposed between the first metal member and the second metal member. Therefore, even if the anode side metal plate and the cathode side metal plate are joined by welding, the anode and the cathode can be electrically insulated.

  In any one of the above fuel cells, the fuel gas supplied to the anode and the cathode are in contact with the anode side metal plate and the cathode side metal plate, respectively, around the membrane electrode assembly. A gasket for separating the oxidant gas supplied to the gas generator may be provided. By doing so, the cross leak between the fuel gas and the oxidant gas in the fuel cell can be suppressed.

  The present invention can also be configured as an invention of a method for manufacturing a fuel cell. That is, the fuel cell manufacturing method of the present invention includes a membrane electrode assembly in which an anode and a cathode are joined to both surfaces of an electrolyte membrane, respectively, and an anode side metal plate and a cathode to the anode and the cathode, respectively. The gist of the present invention is to include the step of bringing the side metal plate into contact with and the step of joining the peripheral portion of the anode side metal plate and the peripheral portion of the cathode side metal plate together by welding. By doing so, the fuel cell of the present invention described above can be manufactured. In the fuel cell manufacturing method of the present invention, the various additional elements described above can be applied.

Hereinafter, embodiments of the present invention will be described based on examples.
A. Fuel cell configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell 100 as one embodiment of the present invention. Here, the cross-sectional structure of the fuel cell 100 is shown.

  As shown in the figure, the fuel cell 100 has an anode side catalyst layer 20a and an anode side gas diffusion layer 30a joined to one surface of the electrolyte membrane 10 in this order, and the other side of the electrolyte membrane 10 to the cathode side. A membrane electrode assembly 52 formed by joining the catalyst layer 20c and the cathode side gas diffusion layer 30c in this order is provided (in FIG. 1, for convenience of illustration, the membrane electrode assembly is provided with a reference numeral). Absent). In this embodiment, a solid polymer film such as Nafion (registered trademark) is used as the electrolyte film 10. Other electrolyte membranes may be used as the electrolyte membrane 10. In this example, carbon cloth having conductivity and gas diffusibility is used as the anode side gas diffusion layer 30a and the cathode side gas diffusion layer 30c. For example, carbon paper may be used instead of carbon cloth.

  A gasket 54 having gas impermeability and sealing properties is disposed around the membrane electrode assembly 52 (hereinafter, the membrane electrode assembly having the gasket 54 disposed therein is referred to as “membrane electrode”). It is referred to as a “zygote unit 50”. In FIG. 1, for convenience of illustration, the membrane electrode assembly unit is not denoted by a reference numeral). A metal porous body 40a that constitutes a flow path of hydrogen as a fuel gas is disposed on the surface of the anode side gas diffusion layer 30a, and an oxidant gas as an oxidant gas is disposed on the surface of the cathode side gas diffusion layer 30c. A metal porous body 40c constituting an air flow path is disposed. The anode side catalyst layer 20a, the anode side gas diffusion layer 30a, and the metal porous body 40a correspond to the anode in the present invention. The cathode side catalyst layer 20c, the cathode side gas diffusion layer 30c, and the metal porous body 40c correspond to the cathode in the present invention.

  On the anode side of the membrane electrode assembly unit 50, an anode side metal plate 60a having a hydrogen supply port 60ai and an anode offgas discharge port 60ao is disposed. The anode-side metal plate 60a contacts the anode-side surface of the gasket 54, seals hydrogen flowing in the metal porous body 40a and the anode off-gas, and contacts the surface of the metal porous body 40a. And electrical continuity between the anode side metal plate 60a and the anode side metal plate 60a.

  A cathode side metal plate 60c having an air supply port 60ci and a cathode offgas discharge port 60co is disposed on the cathode side of the membrane electrode assembly unit 50. The cathode-side metal plate 60c abuts on the cathode-side surface of the gasket 54, seals the air flowing in the metal porous body 40c and the cathode offgas, and abuts on the surface of the metal porous body 40c. And electrical conduction between the cathode side metal plate 60c and the cathode side metal plate 60c. As will be described later, an insulating member 62 is provided in a region inside the peripheral edge of the cathode side metal plate 60c.

  In this embodiment, as will be described later, the peripheral edge portion 60e of the anode side metal plate 60a and the peripheral edge portion 60e of the cathode side metal plate 60c are joined and sealed by laser welding. In the illustrated example, for the convenience of illustration, the peripheral edge portion 60e of the anode side metal plate 60a and the peripheral edge portion 60e of the cathode side metal plate 60c are drawn as if being bent. However, the bending process is not necessarily required, and may be performed when necessary for laser welding.

  FIG. 2 is an explanatory view showing components constituting the fuel cell 100. FIG. 2A shows a plan view of the membrane electrode assembly unit 50. FIG. 2B shows a plan view of the cathode side metal plate 60c. FIG. 2C shows a plan view of the anode side metal plate 60a.

  As shown in FIG. 2A, the membrane electrode assembly unit 50 has a rectangular shape, and a gasket 54 is arranged around the membrane electrode assembly 52 having a rectangular shape. As shown in the drawing, in this embodiment, the vertical length of the membrane electrode assembly unit 50 is h1, and the horizontal length is w1. These lengths can be arbitrarily set. Although not shown, the metal porous bodies 40 a and 40 c have substantially the same shape as the membrane electrode assembly 52.

  Further, as shown in FIG. 2B, the cathode side metal plate 60c has a rectangular flat plate shape, and the first metal member 61 having the rectangular shape and the first metal member 61 have a rectangular shape. The insulating member 62 joined to the periphery and the second metal member 63 joined to the periphery of the insulating member 62 are configured. As the insulating member 62, for example, rubber, resin, or the like can be used. A region indicated by a broken line in FIG. 2B indicates a region corresponding to a region where the membrane electrode assembly 52 is disposed when the cathode side metal plate 60c is brought into contact with the membrane electrode assembly unit 50. ing. As shown in the drawing, in the region corresponding to the lower end portion of the membrane electrode assembly 52 and the region corresponding to the upper end portion of the first metal member 61, there are a plurality of through holes, that is, a plurality of air. A supply port 60ci and a plurality of cathode offgas discharge ports 60co are formed respectively.

  The vertical length of the first metal member 61 is h2, and the horizontal length is w2. The vertical length h2 of the first metal member 61 is set to be longer than the vertical length h1 of the gasket 54, and the horizontal length w2 of the first metal member 61 is It is set longer than the lateral length w1 of the gasket 54. Therefore, the cathode of the membrane electrode assembly 52 does not contact the second metal member 63, and the cathode of the membrane electrode assembly 52 and the second metal member 63 are separated by the insulating member 62. It is electrically insulated.

  Further, as shown in FIG. 2C, the anode side metal plate 60a has a rectangular flat plate shape having the same size as the cathode side metal plate 60c. The area indicated by the broken line in FIG. 2C corresponds to the area where the membrane electrode assembly 52 is arranged when the anode side metal plate 60a is brought into contact with the membrane electrode assembly unit 50. Is shown. As shown in the drawing, a plurality of through holes, that is, a plurality of hydrogen supply ports are formed in the region corresponding to the upper end portion of the membrane electrode assembly 52 and the region corresponding to the lower end portion of the anode side metal plate 60a. 60ai and a plurality of anode off-gas exhaust ports 60ao are formed.

B. Fuel cell manufacturing process:
FIG. 3 is an explanatory view showing the manufacturing process of the fuel cell 100. In addition, in the frame which shows each process, sectional drawing of a part of component which comprises the fuel cell 100 was shown collectively.

  First, the membrane electrode assembly unit 50, the cathode side metal plate 60c, and the anode side metal plate 60a are manufactured (steps S100 and 110). The porous metal body 40c is disposed on the surface of the cathode-side gas diffusion layer 30c of the membrane electrode assembly 52, and the porous metal body 40a is disposed on the surface of the anode-side gas diffusion layer 30a. The cathode side metal plate 60c and the anode side metal plate 60a are brought into contact with the surfaces, respectively (step S120). And the peripheral part 60e of the cathode side metal plate 60c and the peripheral part 60e of the anode side metal plate 60a are joined and sealed by laser welding (step S130). In the illustrated example, for the convenience of illustration, the peripheral edge portion 60e of the anode side metal plate 60a and the peripheral edge portion 60e of the cathode side metal plate 60c are drawn as if being bent. However, as described above, the bending process is not always necessary, and may be performed when necessary for laser welding. The fuel cell 100 is completed through the above steps.

  According to the fuel cell 100 of the present embodiment described above, the peripheral edge portion 60e of the anode side metal plate 60a and the peripheral edge portion 60e of the cathode side metal plate 60c are joined by laser welding. Thus, it is not necessary to provide an area for “caulking” at the peripheral edge portion 60e of the anode side metal plate 60a and the peripheral edge portion 60e of the cathode side metal plate 60c. Therefore, the peripheral edge portion 60e of the anode side metal plate 60a and the peripheral edge portion 60e of the cathode side metal plate 60c can be sealed while reducing the size of the cathode side metal plate 60c and the anode side metal plate 60a. . Further, in the fuel cell 100 of the present embodiment, the cathode side metal plate 60c includes the insulating member 62, so that electrical insulation between the anode and the cathode can be ensured. Further, when the peripheral edge portion 60e of the cathode side metal plate 60c and the peripheral edge portion 60e of the anode side metal plate 60a are sealed by “caulking”, mechanical damage may be applied to the cathode and the anode. However, according to the fuel cell 100 of the present embodiment, this fear can be eliminated.

C. Variation:
Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and can be implemented in various modes without departing from the scope of the present invention. For example, the following modifications are possible.

C1. Modification 1:
In the said Example, although the anode side metal plate 60a and the cathode side metal plate 60c were joined by laser welding, this invention is not limited to this. The anode side metal plate 60a and the cathode side metal plate 60c may be joined by other welding methods.

C2. Modification 2:
In the said Example, although the cathode side metal plate 60c shall be provided with the insulating member 62, this invention is not limited to this. Instead of the cathode side metal plate 60 c, the anode side metal plate 60 a may be provided with the insulating member 62.

C3. Modification 3:
In the said Example, although the metal porous bodies 40a and 40c shall be arrange | positioned on both surfaces of the membrane electrode assembly 52, this invention is not restricted to this, It is good also as what does not arrange | position these. The electrical connection between the anode of the membrane electrode assembly 52 and the anode side metal plate 60a and the flow path of the fuel gas on the anode are ensured, and the electrical connection between the cathode of the membrane electrode assembly 52 and the cathode side metal plate 60c. It is only necessary to ensure general conduction and a flow path for the oxidant gas on the cathode.

It is explanatory drawing which shows schematic structure of the fuel cell 100 as one Example of this invention. FIG. 3 is an explanatory diagram showing components that constitute the fuel cell 100. 5 is an explanatory view showing a manufacturing process of the fuel cell 100. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Fuel cell 10 ... Electrolyte membrane 20a ... Anode side catalyst layer 20c ... Cathode side catalyst layer 30a ... Anode side gas diffusion layer 30c ... Cathode side gas diffusion layer 40a, 40c ... Metal porous body 50 ... Membrane electrode assembly unit 52 ... Membrane electrode assembly 54 ... Frame member 60a ... Anode-side metal plate 60c ... Cathode-side metal plate 60e ... Peripheral portion 60ai ... Hydrogen supply port 60ci ... Air supply port 60ao ... Anode off-gas discharge port 60co ... Cathode off-gas discharge port 61 ... First Metal member 62 ... Insulating member 63 ... Second metal member

Claims (4)

A fuel cell,
A membrane electrode assembly formed by bonding an anode and a cathode to both surfaces of the electrolyte membrane, and
An anode side metal plate having a fuel gas supply port for supplying fuel gas to the anode, and in contact with the anode;
A cathode side metal plate having an oxidant gas supply port for supplying an oxidant gas to the cathode and contacting the cathode;
The peripheral portion of the anode side metal plate and the peripheral portion of the cathode side metal plate are joined together by welding,
The anode side metal plate or the cathode side metal plate includes an insulating structure that electrically insulates the anode and the cathode.
Fuel cell. The fuel cell according to claim 1, wherein
The anode side metal plate or the cathode side metal plate is
As the insulating structure,
A first metal member in contact with the anode or the cathode;
An insulating member joined around the first metal member;
A second metal member joined around the insulating member;
A fuel cell comprising: The fuel cell according to claim 1 or 2,
Around the membrane electrode assembly, the anode side metal plate and the cathode side metal plate are brought into contact with each other, and the fuel gas supplied to the anode and the oxidant gas supplied to the cathode are separated. A fuel cell comprising a gasket. A fuel cell manufacturing method comprising:
A process for producing a membrane electrode assembly in which an anode and a cathode are respectively bonded to both surfaces of an electrolyte membrane;
A step of producing an anode side metal plate having a fuel gas supply port for supplying fuel gas to the anode and contacting the anode;
A step of producing a cathode side metal plate that has an oxidant gas supply port for supplying an oxidant gas to the cathode and is in contact with the cathode;
Contacting the anode side metal plate and the cathode side metal plate with the anode and the cathode, respectively;
Bonding the peripheral edge of the anode side metal plate and the peripheral edge of the cathode side metal plate to each other by welding;
A manufacturing method comprising:

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