JPH09167623A - Solid polymer electrolyte fuel cell - Google Patents

Abstract

(57) [PROBLEMS] To provide a fuel cell that has a simple structure for sealing a fuel gas and an oxidant gas supplied to a single cell, is inexpensive, and requires a small space. SOLUTION: In a unit cell, an anode 2 and a cathode 3 are arranged on both main surfaces of an electrolyte membrane 1 made of a solid polymer electrolyte, and a separator 4C having a fuel gas flow groove 6 on both surfaces thereof and an oxidant gas. In the structure configured by arranging the separator 5C having the flow-through groove 7, the sealing surface 40 of the separator 4C
A and the seal surface 50A of the separator 5C are formed into a smooth surface, and the electrolyte membrane 1 is pressed and sandwiched between them, and the space between the seal surface 40A and the electrolyte membrane 1 and between the seal surface 50A and the electrolyte membrane 1 are Keep airtight.

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 which uses a solid polymer electrolyte membrane as an electrolyte holding layer to generate electricity by an electrochemical reaction, and in particular, a gas-tight reaction gas of a unit cell constituting the solid polymer electrolyte fuel cell Regarding the structure.

[0002]

2. Description of the Related Art FIG. 5 is an exploded sectional view schematically showing a typical constitutional example of a unit cell of a solid polymer electrolyte fuel cell which has been conventionally used. An anode 2 and a cathode 3 are closely laminated on two main surfaces of an electrolyte membrane 1 made of a solid polymer electrolyte, and separators 4 and 5 made of a gas impermeable material are further arranged on both outer surfaces of the electrolyte membrane 1 to form a single cell. On the inner surface of the separator 4 facing the anode 2, a fuel gas flow groove 6 for supplying the fuel gas from the outside to the anode 2 and discharging the surplus gas, and on the outer surface of the separator 4. Is provided with a cooling water flow channel 8 for passing cooling water for removing heat generated by power generation and maintaining the temperature at a predetermined temperature. Similarly, the inner surface of the separator 5 is provided with an oxidizing gas flow channel 6 A cooling water flow groove 8 is provided on the outer surface.

The solid polymer electrolyte used for the electrolyte membrane 1 uses a polystyrene cation exchange membrane having a sulfonic acid group as a cation conductive membrane, a mixed membrane of fluorocarbon sulfonic acid and polyvinylidene fluoride, and a fluorocarbon. A matrix in which trifluoroethylene is graphitized, or perfluorocarbon sulfonic acid (trade name: Nafion membrane manufactured by DuPont, USA) is known. Anode 2 and cathode 3
Both are usually composed of a catalyst layer composed of a platinum catalyst and a fluororesin, and an electrode base material that supports this catalyst layer, and the electrode base material simultaneously permeates the reaction gas to the catalyst layer. It plays a role of supplying and a role of current collector.

Since the generated voltage of the unit cell constructed in this way is 1 V or less, when constructing a fuel cell,
A method of increasing the voltage by stacking a plurality of unit cells into a stack is adopted. FIG. 6 is a schematic diagram showing the basic structure of a stack of a solid polymer electrolyte fuel cell that has been conventionally used. The unit cells 9 are stacked, the current collector plates 10 are arranged at both ends thereof, the insulating plates 11 which serve as electric insulation and thermal insulation are arranged on the outer sides thereof, and the plates are sandwiched between the tightening plates 11, and the disc springs 13 are inserted. It is tightened with the tightening bolt 15 and the nut 14, and is pressurized and held at a predetermined pressure.

FIG. 7 is a schematic view showing the basic structure of a separator of a unit cell by way of example of a separator 4 facing the anode 2. FIG. 7A is a plan view thereof, and FIG. 7B is a plan view thereof. It is sectional drawing in the XX plane. As shown in (a), a plurality of fuel gas flow grooves 6 are arranged facing the anode 2 in the center of the anode-side main surface of the separator 4. The fuel gas supplied from the outside is the fuel gas inlet 23.
After being introduced, the gas is diverted from the inlet-side manifold 21 to the plurality of fuel gas flow grooves 6, and is supplied to the power generation. Then, the surplus gas is discharged from the outlet-side manifold 24 to the outside. Note that the oxidant gas inlet communication hole 25 and the oxidant gas outlet communication hole 26 are holes that communicate with the oxidant gas inlet and the oxidant gas outlet of the separator 5 that is disposed opposite to the separator 4, and these communication holes. The oxidant gas is supplied to and discharged from the separator 5 through the.

As described above, in the solid polymer electrolyte fuel cell, the fuel gas flows to the anode 2 side and the oxidant gas flows to the cathode 3 side, so that the unit cell keeps these gases airtight. It is necessary to have a structure that FIG. 8 is an exploded cross-sectional view of a single cell showing an example of a conventionally used airtight holding structure. In this configuration, the O-ring groove is provided in the seal surface 40 on the main surface of the separator 4A on the anode 2 side outside the fuel gas passage including the fuel gas passage groove 6, and the O-ring 19 is incorporated therein to face each other. Similarly, an O-ring groove is similarly provided in the seal surface 50 of the main surface of the separator 5A on the cathode 3 side to incorporate the O-ring 19, and the electrolyte membrane 1 is pressed and sandwiched so that the electrolyte membrane 1 and the O-ring 19 are separated from each other. The space is made airtight, and the airtightness between the fuel gas and the oxidant gas is maintained.

FIG. 9 is an exploded cross-sectional view of a unit cell showing another example of a conventionally used airtight holding structure. In this structure, a sheet packing 20 is used instead of the O-ring 19 of FIG. There is.

[0008]

As described above, in the conventional solid polymer electrolyte fuel cell, the fuel gas and the oxidizer are provided by the O-ring 19 or the sheet packing 20 provided outside the main surface of the separator. A method of maintaining airtightness with the gas is adopted. However, in the solid polymer electrolyte fuel cell having this configuration, (1) since the sealing material such as the O-ring 19 and the sheet packing 20 is sandwiched, the thickness of the unit cell becomes large, and the cells are stacked. It becomes difficult to miniaturize the formed solid polymer electrolyte fuel cell.

(2) Since the solid polymer electrolyte is acidic,
It is necessary to use an acid-resistant sealing material or to insert an acid-resistant inclusion between the electrolyte membrane and the sealing material, and this is because the acid-resistant sealing material and acid-resistant inclusion are expensive. The manufacturing cost of the solid polymer electrolyte fuel cell used is high. There are difficulties such as.

The present invention has been made in consideration of the problems of the prior art as described above, and an object thereof is to keep the fuel gas and the oxidant gas supplied to the unit cell airtight with each other by a simple structure. An object of the present invention is to provide an inexpensive and space-saving solid polymer electrolyte fuel cell.

[0011]

In order to achieve the above object, in the present invention, (1) an electrode layer is disposed in close contact with the central portions of both main surfaces of a solid polymer electrolyte membrane, and On both sides of the solid polymer electrolyte fuel cell, a single cell is formed by arranging a separator provided with a reaction gas flow groove facing the electrode layer, and a plurality of the single cells are laminated. The main surface of the two separators, which is located outside the reaction gas flow groove, is used as a sealing surface, and the electrode layer non-installed portion of the solid polymer electrolyte membrane is sandwiched between the two sealing surfaces to hermetically seal the reaction gas. I will hold it.

(2) In the above (1), one of the two sealing surfaces is a smooth surface, and a continuous projection is provided on the outer periphery of the electrode layer installation portion of the other sealing surface. (3) Alternatively, in the above (1), one of the two sealing surfaces is a smooth surface, and a continuous groove is provided on the outer periphery of the electrode layer installation portion of the other sealing surface.

(4) Alternatively, in the above (1), a projection is provided continuously on the outer periphery of the electrode layer installation portion of one of the two sealing surfaces, and the other sealing surface is provided with this projection. It shall be equipped with continuous concave grooves that fit together.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the solid polymer electrolyte fuel cell of the present invention will be described below with reference to examples. FIG.
FIG. 2 is a schematic view of an exploded cross section of a single cell showing a first embodiment of the solid polymer electrolyte fuel cell of the present invention. In the figure, components having the same functions as those of the conventional example shown in FIG. 8 or 9 are designated by the same reference numerals, and a duplicate description will be omitted.

The difference between the configuration of this figure and the configuration of the conventional example shown in FIG. 8 or 9 lies in the configuration of the sealing surface. In the conventional example, a groove is formed in the sealing surface 40 and the sealing surface 50.
While the sealing material such as the ring 19 or the sheet packing 20 is arranged, the sealing surface 40
The difference is that the surfaces of A and the sealing surface 50A are formed as smooth surfaces. In this configuration, the electrolyte membrane 1 is sandwiched between the smooth surface of the sealing surface 40A and the smooth surface of the sealing surface 50A,
By pressurizing and holding the seal surface 40A, the space between the smooth surface of the seal surface 40A and the electrolyte membrane 1 and the space between the smooth surface of the seal surface 50A and the electrolyte membrane 1 are made airtight, and between the fuel gas and the oxidant gas Keeps hermetically sealed. Therefore, the use of this configuration eliminates the need for arranging a sealing material as in the conventional example, which reduces the manufacturing cost and can reduce the thickness to a small value. The battery will be made small.

FIG. 2 is a schematic view of an exploded cross section of a unit cell showing a second embodiment of the solid polymer electrolyte fuel cell of the present invention. The feature of the configuration of this figure is that the surface of the sealing surface 40A of the separator 4C is formed as a smooth surface and the opposing separator 5
The point is that a continuous minute rectangular protrusion 22 is formed on the sealing surface 50B of D so as to surround the flow path of the oxidant gas. Therefore, in this configuration, airtightness is more reliably ensured between the electrolyte membrane 1 and the rectangular protrusion 22 portion of the seal surface 50B, and between the electrolyte membrane 1 and the smooth surface of the seal surface 40A facing the rectangular protrusion 22. Will be kept. Also in this configuration, since it is not necessary to dispose a sealing material as in the conventional example, the manufacturing cost is reduced, and the rectangular protrusion 22 is used.
Since it suffices to form minutely, a solid polymer electrolyte fuel cell using the same can be miniaturized.

Although the rectangular protrusion 22 is formed in this example, the protrusion is not limited to a rectangle, and may be, for example, an inverted V-shaped protrusion. FIG. 3 is a schematic view of an exploded cross section of a single cell showing a third embodiment of the solid polymer electrolyte fuel cell of the present invention. The feature of the configuration of this drawing is that the surface of the sealing surface 40A of the separator 4C is formed to be a smooth surface, and a V-shaped recess 23 that surrounds the flow path of the oxidant gas and is continuous is formed in the sealing surface 50C of the opposing separator 5E. There is a point. In this configuration, the airtightness is more reliably ensured between the V-shaped recess 23 of the sealing surface 50C and the electrolyte membrane 1 and between the smooth surface of the sealing surface 40A facing the V-shaped recess 23 and the electrolyte membrane 1. Therefore, it can be formed at low cost and in a small size.

Although the V-shaped recess 23 is formed in this example, the V-shaped recess 23 is not limited to the V-shaped recess 23, and may be, for example, a rectangular recessed shape. FIG. 4 is a schematic diagram of an exploded cross section of a unit cell showing a fourth embodiment of the solid polymer electrolyte fuel cell of the present invention. The feature of the configuration of this figure is that the seal surface 50C of the separator 5E is a continuous V that surrounds the flow path of the oxidant gas.
The mold recess 23 is formed, and a continuous inverted V-shaped projection 24 that fits into the V-shaped recess 23 is formed on the opposing sealing surface 40B of the separator 4D. In the present configuration, the airtightness can be more reliably maintained between the V-shaped recess 23 and the electrolyte membrane 1 and between the electrolyte membrane 1 and the inverted V-shaped projection 24, which is inexpensive and small in size. It will be possible.

In this example, the V-shaped recess 23 and the inverted V-shaped projection 24 are combined, but the invention is not limited to the V-shaped, and for example, a combination of a rectangular recess and a rectangular projection is also possible. The same effect can be obtained.

[0020]

As described above, according to the present invention, since (1) the solid polymer electrolyte fuel cell is constructed as described in claim 1, the special sealing between the two sealing surfaces is adopted. Since it is not necessary to incorporate a sealing material, it is possible to obtain an inexpensive and space-saving solid polymer electrolyte fuel cell.

(2) Further, in the above solid polymer electrolyte fuel cell, according to the second, third or fourth aspect, the reaction gas can be held more surely, so that it is cheap and economical. It is more suitable as a solid polymer electrolyte fuel cell for space.

[Brief description of the drawings]

FIG. 1 is a schematic view of an exploded cross section of a unit cell showing a first embodiment of a solid polymer electrolyte fuel cell of the present invention.

FIG. 2 is a schematic view of an exploded cross section of a unit cell showing a second embodiment of the solid polymer electrolyte fuel cell of the present invention.

FIG. 3 is a schematic view of an exploded cross section of a unit cell showing a third embodiment of the solid polymer electrolyte fuel cell of the present invention.

FIG. 4 is a schematic view of an exploded cross section of a unit cell showing a fourth embodiment of the solid polymer electrolyte fuel cell of the present invention.

FIG. 5 is a schematic diagram of an exploded cross section showing a typical configuration example of a unit cell of a conventional solid polymer electrolyte fuel cell

FIG. 6 is a schematic diagram showing the basic structure of a stack of a conventional solid polymer electrolyte fuel cell.

FIG. 7 is a schematic diagram showing a basic configuration of a battery cell separator.

FIG. 8 is an exploded cross-sectional view of a unit cell showing an example of a conventionally used airtight holding structure.

FIG. 9 is an exploded cross-sectional view of a unit cell showing another example of a conventionally used airtight holding structure.

[Explanation of symbols]

 1 Electrolyte Membrane 2 Anode 3 Cathode 4C, 4D Separator 5C, 5D Separator 5E, 5F Separator 6 Fuel Gas Flow Groove 7 Oxidant Gas Flow Groove 8 Cooling Water Flow Groove 22 Rectangular Protrusion 23 V-Type Recess 24 V-Type Protrusion 40A , 40B sealing surface 50A, 50B sealing surface 50C sealing surface

Claims (4)

[Claims] 1. A solid polymer electrolyte membrane, in which electrode layers are arranged in close contact with each other at the central portions of both main surfaces, and a separator having a reaction gas flow groove is arranged on both surfaces of the solid polymer electrolyte membrane so as to face the electrode layers. To form a single cell, and in a solid polymer electrolyte fuel cell constituted by stacking a plurality of the single cells, the main surface located outside the reaction gas flow groove of the two separators is the sealing surface. The solid polymer electrolyte fuel cell is characterized in that a portion of the solid polymer electrolyte membrane where the electrode layer is not provided is sandwiched between the two sealing surfaces to keep the reaction gas airtight. 2. The solid polymer electrolyte fuel cell according to claim 1, wherein one of the two sealing surfaces has a smooth surface, and the other has a continuous surface on the outer periphery of the electrode layer installation portion. And a solid polymer electrolyte fuel cell. 3. The solid polymer electrolyte fuel cell according to claim 1, wherein one of the two sealing surfaces has a smooth surface, and the other is continuously arranged on the outer periphery of the electrode layer installation portion. Solid polymer electrolyte fuel cell, characterized by comprising: 4. The solid polyelectrolyte fuel cell according to claim 1, wherein one of the two sealing surfaces comprises a protrusion arranged continuously on the outer periphery of the electrode layer installation portion. The solid polymer electrolyte fuel cell is characterized in that the other has a concave groove that fits into this protrusion.