JPH05283093A - Solid highpolymer electrolyte fuel cell - Google Patents

Abstract

PURPOSE:To provide the solid highpolymer electrolyte fuel cell, in which the gas sealing property at the periphery of a gas diffusion electrode is secured and which has a high degree of freedom in the selection of the operating condition. CONSTITUTION:A highpolymer electrolyte film 11, frame-like fine rubber sheets 102, 103 provided in the periphery of the film surface of the highpolymer electrolyte film, gas diffusion electrodes 12, which respectively contacts inside of notch parts 102a, 103a of the frame-like fine rubber sheets 102, 103 at the central part of the film surface are bonded by the thermocompression bonding to form a power generating element 101 to be pinched by separators with groove. The obtained power generating element 101 and the separators with groove are laminated to obtain a power generating stack having the excellent gas sealing property.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid polymer electrolyte fuel cell utilizing the ionic conductivity of a solid polymer electrolyte membrane.

[0002]

2. Description of the Related Art An example of a conventional solid polymer electrolyte fuel cell is shown in FIG. As shown in the figure, the solid polymer electrolyte fuel cell has a solid polymer electrolyte membrane 11 having hydrogen ion conductivity.
And a water repellent porous carbon electrode (hereinafter, referred to as “gas diffusion electrode”) 12 and 13 supporting platinum catalysts provided on both surfaces of the electrolyte membrane 11.
And a fuel gas (for example, H ₂ ) which is provided so as to sandwich both sides of the power generation element 14 and is connected to one of the gas diffusion electrodes.
Is provided with grooved separators 15 and 16 for respectively supplying an oxidizing gas (for example, O ₂ or air) to the other, and gas is supplied to each of the grooved separators 15 and 16 to generate electric power to generate a groove. The current is taken out from the separators 15 and 16.

The grooved separators 15 and 16 are provided with gas passages 15a and 16a on both sides. One gas passage 15a contains hydrogen as a fuel gas and the other gas passage 16a contains oxygen as an oxidizing gas. Or, each air is supplied.

By the way, in order to prevent the fuel gas and the oxidizing gas from being mixed with each other, it is necessary to provide a gas seal portion where the two gases meet. The places where the gas seal portion is required are the inside of the grooved separator, the inlet and outlet of fuel gas and oxidizing gas, which are adjacent to the manifold, and the side surface of the gas diffusion electrode.

Regarding the inside of the grooved separator in the gas seal portion, by using a gas impermeable material such as metal or dense carbon for the grooved separator,
Gas sealing is possible, and this sealing method has been conventionally used. Further, regarding the adjacent portion of the manifold, gas sealing is performed by a conventional method such as covering each manifold with a closed container.

On the other hand, with respect to the side surface of the gas diffusion electrode 12, as shown in FIG. 6, for example, a caulking agent 17 is used, the caulking agent 17 is thinly applied to the peripheral edges of the gas diffusion electrodes 12 and 13, and the gas diffusion electrode 12 is pressure-bonded. , 13 are crushed and the gas is sealed.

[0007]

However, regarding the gas seals on the side surfaces of the gas diffusion electrodes 12 and 13 in the fuel cell of the prior art, it is difficult to select the thickness of the caulking agent 17 used for the gas seals.

That is, as shown in FIG. 7, if the thickness of the caulking agent 17 is too thick, the gas diffusion electrode 1 can be pressed even if it is pressure-bonded.
There is a problem that the contact between the grooved separators 2 and 13 and the grooved separators 15 and 16 is lost, and a gap 18 is generated, and as a result, the function of extracting the electric current from the portion 19 that requires electrical connection is impaired.

On the contrary, if the thickness of the caulking agent 17 is too thin, as shown in FIG. 8, the side surfaces of the gas diffusion electrodes 12 and 13 are not sufficiently crushed and there is a problem that gas sealing cannot be performed.

Further, in the gas sealing method according to the prior art, when there is a pressure difference between both sides of the sealing portion, the gas sealing cannot be effectively performed, and the gas leakage 20 occurs and the operating condition is restricted. There is a problem (the allowable pressure difference in the current sealing method is about 0.1 to 0.2 MPa).

On the other hand, there is a demand for a simpler and more reliable gas sealing method in order to surely seal the gas around the gas diffusion electrode and to increase the degree of freedom in selecting operating conditions, particularly operating pressure.

In view of the above-mentioned circumstances, it is an object of the present invention to provide a solid polymer electrolyte fuel cell which can surely seal the gas around the gas diffusion electrode and has a high degree of freedom in selecting operating conditions. ..

[0013]

Means for Solving the Problems A solid polymer electrolyte fuel cell according to the present invention which achieves the above object comprises a power generation element comprising a polymer electrolyte membrane sandwiched between gas diffusion electrodes, and the above gas diffusion. In a solid polymer electrolyte fuel cell in which a grooved separator that supplies a fuel gas to one of the electrodes and a oxidant gas that supplies to the other are laminated on each other, the power generating element comprises a polymer electrolyte membrane and a membrane of the polymer electrolyte membrane It is characterized by comprising a dense rubber sheet provided at the peripheral portion of the surface and a gas diffusion electrode provided at the central portion of the film surface.

[0014]

[Function] Since the dense rubber sheet is provided on the periphery of the electrolyte membrane and the gas diffusion electrode is provided at the center of the membrane surface to perform pressure bonding to form the power generating element, there is no need to apply a caulking agent as in the conventional case. By stacking the power generation element and the grooved separator, a power generation stack of a solid polymer electrolyte fuel cell can be formed. Further, the electrical contact between the gas diffusion electrode and the grooved separator and the gas seal on the side surface of the gas diffusion electrode are simultaneously satisfied.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the solid polymer electrolyte fuel cell according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram of a power generating element of a solid polymer electrolyte fuel cell. FIG. 2 shows a schematic view of the manufacturing process. As shown in these drawings, in the solid polymer electrolyte fuel cell according to the present embodiment, the power generation element 101 sandwiched between the grooved separators includes the polymer electrolyte membrane 11 and the membrane surface 11a of the polymer electrolyte membrane. The frame-shaped dense rubber sheets 102 and 103 provided on the peripheral portion, and the cutout portion 102 of the frame-shaped dense rubber sheets 102 and 103 at the center of the film surface 11a.
a, 103a and the gas diffusion electrodes 12 and 13 inscribed inside.

That is, as shown in FIGS. 2A to 2C, the portions of the gas diffusion electrodes 12, 13 to which the conventional caulking agent is applied are cut out, and the gas diffusion electrodes 1 are formed in the portions.
Frame-shaped dense rubber sheet 10 having substantially the same thickness as 2 and 13
2, 103 are provided, and the polymer electrolyte membrane 11 and the gas diffusion electrodes 12 and 13 are subjected to a thermocompression bonding step (see FIG. 2B) by, for example, a hot pressing method or the like.
The gas diffusion electrode is provided at the center of the film surface 11a of No. 1 and the dense rubber sheets 102 and 103 are provided at the peripheral edge thereof to form the pressure-bonding power generation element 101 (FIG. 2 (C)). reference).

The frame-shaped dense rubber sheets 102, 103
It is preferable that the thickness of the gas diffusion electrodes 12 and 13 is substantially the same, or that the frame-shaped dense rubber sheet arranged in the peripheral portion is slightly thicker in terms of adhesion. In addition, in FIG.
Reference numeral 04 denotes a press plate used in the hot pressing process.

Next, the outline of specific manufacturing of the power generation stack of the fuel cell will be described with reference to FIGS. 3 and 4. The polymer electrolyte membrane 11 has a thickness of 0.1 to 0.2 mm and a size of 2
A 30 mm × 230 mm square one was used. The gas diffusion electrodes 12 and 13 have a thickness of 0.5 to 1.0 mm.
A square one having a size of 200 m × 200 mm was used. The dense rubber sheets 102 and 103 are thicker than the gas diffusion electrodes 12 and 13 by about 0.2 to 0.3 mm, and are 230 mm × 230 mm and 200 m × 20.
Notch 1 where 0 mm gas diffusion electrodes 12 and 13 are inscribed
02a, 103a, and a longitudinal elastic modulus slightly smaller than that of the gas diffusion electrode, for example, fluororubber was used.

These are piled up, and the temperature is 350 to 380.
The hot pressing method was carried out under conditions of a pressure reduction time of 1 second to 5 seconds. As a result, the gas diffusion electrodes 12 and 13 and the dense rubber sheets 102 and 103 are respectively thermocompression-bonded to the polymer electrolyte membrane, and the electrode area 400 cm ² (200 mm × 20
0 mm) solid polymer electrolyte fuel cell power generation element 101
Formed.

Thereafter, as shown in FIGS. 3 and 4, the grooved separators 15 and 16 and the power generating element 101 having the above-mentioned rubber sheet portion for gas sealing are laminated on each other and pressure-bonded at a constant pressure to generate a power generating stack. 105 was formed. still,
In the state of the power generating element alone, the rubber sheets 102 and 103 are thicker by about 0.1 to 0.3 mm than the gas diffusion electrodes 12 and 13, but the power generating element 101 and the grooved separators 15 and 16 are overlapped. When the power generation stack 105 is constructed, the rubber sheet 1 is used for stacking at a constant pressure.
02 and 103 and the gas diffusion electrodes 12 and 13 have the same thickness, and the rubber sheet is compressed and deformed to come into close contact with the adjacent gas diffusion electrodes to have a gas sealing function.

As described above, the gas seal portion provided with the dense rubber sheet is provided at the periphery of the membrane surface of the polymer electrolyte membrane, the diffusion electrode is provided therein, and thermocompression bonding is performed, whereby the gas seal rubber is provided. It becomes easy to form a power generation element having a sheet portion, and the power generation element 101 and the grooved separators 15 and 1 obtained are obtained.
The step of forming the power generation stack 105 by superposing 6 and 6 is simpler than in the conventional case (in the past, the caulking agent was applied while strictly controlling the thickness to superimpose the element and the separator).

Therefore, it is possible to perform good gas sealing while maintaining the electrical connection between the power generating element and the grooved separator, that is, the function of taking out the current to the outside. Further, in the portion that seals the hydrogen and the outside air, hydrogen is not detected on the outside air side even when the hydrogen side is pressurized to set the differential pressure against the outside air to 0.3039 MPa, and the gas sealability is improved as compared with the conventional case. Was confirmed.

[0024]

As described in connection with the above embodiments, in the solid polymer electrolyte fuel cell according to the present invention, the power generating element has a dense rubber sheet for gas sealing arranged at the peripheral edge of the membrane surface of the polymer electrolyte membrane. Then, the step of forming the power generation stack by superposing the obtained piezoelectric element and the grooved separator on each other becomes simple, and good gas sealing can be performed while maintaining electrical connection between the two. it can.

[Brief description of drawings]

FIG. 1 is a schematic view of a power generation element of a solid polymer electrolyte fuel cell.

FIG. 2 is a schematic view of a manufacturing process of a power generation element.

FIG. 3 is an exploded perspective view of a power generation stack.

FIG. 4 is a schematic view of manufacturing a power generation stack.

FIG. 5 is a schematic diagram of a fuel cell according to a conventional technique.

FIG. 6 is a schematic view of manufacturing a power generation stack according to the related art.

FIG. 7 is a schematic view of manufacturing a power generation stack according to the related art.

FIG. 8 is a schematic view of manufacturing a power generation stack according to the related art.

[Explanation of symbols]

 11 Polymer Electrolyte Membrane 12, 13 Gas Diffusion Electrode 14 Power Generation Element 15, 16 Grooved Separator 17 Caulking Agent 101 Power Generation Element 102, 103 Dense Rubber Sheet 105 Power Generation Stack

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiharu Watanabe 1-1, Atsunoura-machi, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard (72) Inventor Naotake Mori 1-1, Atsunoura-cho, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industry Co., Ltd.Nagasaki Shipyard

Claims (1)

[Claims] 1. A power generating element composed of a polymer electrolyte membrane sandwiched between gas diffusion electrodes, and a grooved separator for supplying fuel gas to one of the gas diffusion electrodes and oxidizing gas to the other, respectively, are laminated on each other. In the solid polymer electrolyte fuel cell as described above, the power generation element is provided with a polymer electrolyte membrane, a dense rubber sheet provided on a peripheral portion of a membrane surface of the polymer electrolyte membrane, and a central portion of the membrane surface. And a gas diffusion electrode, the solid polymer electrolyte fuel cell.