JP2002231274A - Solid high polymer fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell equipped with a cell structure having no possibility of causing the leakage of reaction gas and cooling water. SOLUTION: A bonding laminate of an electrolyte film and an electrode is formed by disposing the electrode 2 on both surfaces of the electrolyte film 1A equipped with a frame sheet 10 on its periphery, and the cell is structured by holding the bonding laminate between separators. A sealing member 11 to prevent reaction gas and cooling water from leaking by making it interposed between the frame sheet 10 and the separators is fixed to the frame sheet 10 by integrally molding them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polymer electrolyte fuel cell using a polymer membrane as an electrolyte.

[0002]

2. Description of the Related Art Polymer electrolyte fuel cells (PEFC: Poly
A mer Electrolyte Fuel Cell is a fuel cell using a polymer membrane as an electrolyte and has excellent features such as high output density and long battery life. FIG. 4 is an exploded sectional view schematically showing a conventional basic configuration example of a polymer electrolyte fuel cell. As shown in the figure, an electrolyte membrane / electrode assembly formed by thermocompression bonding of electrodes 2 to both main surfaces of a solid polymer electrolyte membrane 1 and a pair of current collectors 3 are sandwiched between a pair of separators 4. Thus, a single cell is formed. A gas flow groove 7 for flowing a reaction gas is formed on the inner surface of the separator 4. A fuel gas containing hydrogen is supplied to the gas flow groove 7 of the separator 4 on the anode side, and a separator gas on the other cathode side. An oxidizing gas containing oxygen is supplied to the gas flow grooves 7 of 4. Further, each separator 4 is provided with a cooling water circulation groove 8 on the outer surface, and by flowing cooling water through the cooling water circulation groove 8, heat generated due to power generation is removed, and the single cell has a predetermined shape. Maintained at operating temperature. Also,
Above and below the separator 4 and the solid polymer electrolyte membrane 1 are provided two manifolds 6 dedicated to two reaction gases and cooling water, respectively. This manifold 6
Is connected to a plurality of single cells constituting the fuel cell stack, and the reaction gas and the cooling water flow from the dedicated inlet side manifold to the outlet side manifold, respectively, in the gas flow groove 7 of the separator 4 or the cooling water flow groove. Flow through 8.

[0005] In the figure, a black circle 5 is a seal member made of an O-ring-shaped fluororubber. In a single cell sandwiched by the separator 4, the leakage of the reaction gas reaching the electrode 2 to the outside is prevented. And plays a role in preventing leakage of the reaction gas flowing through the manifold 6 or the cooling water to the outside.

[0004]

As described above, a single cell is constructed, cooling water is supplied to the cooling water flow groove 8 to maintain a predetermined operating temperature, and hydrogen is supplied to the gas flow groove 7 of the separator 4 on the anode side. If an oxidizing gas containing oxygen is caused to flow into the gas flow groove 7 of the separator 4 on the cathode side, an electrochemical reaction occurs and electric energy is obtained. However, the polymer electrolyte fuel cell of this configuration still has the following problems.

That is, in the configuration shown in FIG.
As described above, between the solid polymer electrolyte membrane 1 and the separator 4, in order to prevent the leakage of the reaction gas that has reached the temperature and the leakage of the reaction gas flowing through the manifold 6 or the cooling water to the outside. An O-ring-shaped sealing member 5 is arranged and pressed and sandwiched. However, since this sealing member 5 is not fixed to the separator 4 or the solid polymer electrolyte membrane 1, There is a possibility of misalignment during assembly. In particular, the solid polymer electrolyte membrane 1 is extremely thin, having a thickness of 30 to 50 μm, and has a low rigidity. There is a strong possibility that the misalignment will increase when pressing and holding. If the mounting position of the seal member 5 shifts as described above, the sealing function becomes incomplete, and there is a risk that the reaction gas or the cooling water leaks.

In order to prevent this displacement, a method is considered in which the sealing member 5 is previously adhered to a predetermined position of the separator 4 or the solid polymer electrolyte membrane 1 and then pressed and sandwiched. If it is adopted, there is a disadvantage that the number of assembling steps increases and the manufacturing cost increases. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a solid polymer fuel which has no risk of leakage of reaction gas or cooling water and which is easy to assemble. It is to provide a battery.

[0007]

In order to achieve the above object, the present invention relates to an electrolyte membrane / electrode assembly formed by thermocompression-bonding electrodes on both sides of an electrolyte membrane having a frame sheet around it. Current collectors disposed on both sides of the electrolyte membrane / electrode assembly, separators sandwiching them, and prevention of leakage of reaction gas or cooling water interposed between the frame sheet and the separator. In a polymer electrolyte fuel cell including a seal member for, the seal member, for example, formed of thermosetting silicone, and molded integrally with the frame sheet by, for example, a liquid injection molding method, for example, The seal members provided on both sides of the frame sheet are connected via a plurality of small holes provided in the frame sheet to be integrally formed with the frame sheet.

As described above, if the seal member is formed integrally with the frame sheet, the seal member is fixed at a predetermined position on the frame sheet, so that there is no displacement during cell assembly. Also, unlike solid polymer electrolyte membranes, which are extremely thin, the frame sheet can be formed to be thicker and more rigid, so that it can bend or deform even when subjected to the stress of the sealing member when it is pressed and clamped. Is suppressed very small, and there is no possibility of causing the displacement of the seal member. Therefore, according to the present invention, the risk of leakage of the reaction gas or the cooling water due to the displacement of the seal member as conventionally seen is avoided.

Further, in this configuration, since the sealing member is fixed to the frame sheet constituting the electrolyte membrane / electrode assembly, the alignment at the time of assembling the cell is extremely easy, and the working process is simplified and shortened. Becomes possible.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view schematically showing a configuration of an electrolyte membrane / electrode assembly in one embodiment of the polymer electrolyte fuel cell of the present invention. FIG. 2 shows this electrolyte membrane.
It is a front view which shows typically the frame sheet used for an electrode assembly.

As shown in FIG. 1, the electrolyte membrane / electrode assembly according to the present embodiment is configured by bonding electrodes 2 to both surfaces of an electrolyte membrane 1A having a frame sheet 10 around the electrolyte membrane. The frame sheet 10 is made of a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin having a thickness of 1 mm.
Is bonded with a modified olefin-based adhesive in the same manner as the bonding of the cover sheet film disclosed in JP-A-11-045729. As shown in FIG. 1, the upper and lower portions of the frame sheet 10 are respectively provided with two through holes 12 for a reaction gas manifold and one through hole 13 for a cooling water manifold. In addition, a sealing member 11 made of thermosetting silicone is integrally formed on the frame sheet 10 by a liquid injection molding method. Leakage of the reaction gas reaching the electrode 2 by the sealing member 11 to the outside, and a manifold Leakage of the reaction gas or cooling water flowing through the through hole for cooling water to the outside is prevented.

As shown in FIG. 2, the frame sheet 10 of the present embodiment has a plurality of small holes 15 along the molded portion of the seal member 11, and is provided on both sides of the frame sheet 10. The sealing member 11 is
, The sealing member 11 is more integrally formed with the frame sheet 10 more firmly. FIG.
1 is an exploded cross-sectional view of a polymer electrolyte fuel cell using the electrolyte membrane / electrode assembly of the present embodiment. In this figure, components having the same functions as those of the conventional configuration shown in FIG. 4 are denoted by the same reference numerals. As can be seen from the figure, in the configuration of the present embodiment, the sealing member 11 is integrated into the electrolyte membrane / electrode assembly, so that the alignment of the cell assembly is extremely easy and the work process is shortened compared to the conventional case. Is done.

In this embodiment, the frame sheet 10
Is formed using a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin, but a resin such as polyethylene terephthalate, polyphenylene sulfide, or polyethylene naphthalate may be used instead of this resin. Further, in the present embodiment, the thickness of the frame sheet 10 is set to 1 mm. However, the present invention is not limited to this, and the same effect can be obtained by forming the frame sheet 10 to a thickness in the range of 0.05 to 2 mm.

[0014]

As described above, according to the present invention, the polymer electrolyte fuel cell is constructed as described in claim 1 and further according to claims 2 to 5, so that the electrolyte membrane / electrode assembly and the separator Is fixed at a predetermined position, and the displacement during cell assembly is suppressed. As a result, a polymer electrolyte fuel cell having no risk of leakage of reaction gas or cooling water and being easy to assemble can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view schematically showing a configuration of an electrolyte membrane / electrode assembly in one embodiment of a polymer electrolyte fuel cell of the present invention.

FIG. 2 is a front view schematically showing a frame sheet used for the electrolyte membrane / electrode assembly of the embodiment shown in FIG.

FIG. 3 is an exploded cross-sectional view schematically showing a configuration of a polymer electrolyte fuel cell using the electrolyte membrane / electrode assembly of the embodiment shown in FIG.

FIG. 4 is an exploded cross-sectional view schematically showing a conventional basic configuration example of a polymer electrolyte fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1A Electrolyte membrane 2 Electrode 3 Current collector 4 Separator 6 Manifold 7 Gas circulation groove 8 Cooling water circulation groove 10 Frame sheet 11 Seal member 11 12 Through hole for reaction gas manifold 13 Through hole for cooling water manifold

Claims (5)

[Claims] 1. An electrolyte membrane / electrode assembly formed by thermocompression bonding electrodes on both sides of an electrolyte membrane having a frame sheet around it, and current collectors arranged on both sides of the electrolyte membrane / electrode assembly. A polymer electrolyte fuel cell comprising: a separator for sandwiching these components; and a seal member interposed between the frame sheet and the separator for preventing leakage of a reaction gas or cooling water. And a solid polymer fuel cell formed integrally with the frame sheet. 2. The polymer electrolyte fuel cell according to claim 1, wherein the seal members disposed on both sides of the frame sheet are connected to the frame sheet through a plurality of small holes provided in the frame sheet. A polymer electrolyte fuel cell, which is integrally molded. 3. The solid polymer fuel cell according to claim 1, wherein the sealing member is a sealing member integrally formed on a frame sheet by a liquid injection molding method. Molecular fuel cell. 4. The polymer electrolyte fuel cell according to claim 1, wherein said frame sheet is made of a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, polyethylene terephthalate, polyphenylene sulfide, or polyethylene naphthalene. A polymer electrolyte fuel cell comprising any one of phthalates. 5. The polymer electrolyte fuel cell according to claim 1, wherein said sealing member is made of thermosetting silicone.