JPH0521076A - Fuel battery - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a fuel cell which can control the cell temperature at a constant level without increasing the cell stack height and can always generate power at an optimum temperature. [Constitution] Battery main body 2 and reaction gas supply plate 1,
A fuel cell comprising 3, 4 fuel cells, characterized in that a groove 9 for circulating cooling water is arranged on at least one surface of the reaction gas supply plates 1, 3, 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell, and more particularly to improvement of its cooling structure.

[0002]

2. Description of the Related Art A fuel cell directly converts chemical energy into electric energy, and in order to increase the power generation capacity, unit cells are stacked and connected in series. However, when power is generated in the fuel cell, the cell temperature rises due to reaction heat and contact resistance between the electrode and the reaction gas supply plate. In particular, in a fuel cell using an ion exchange membrane, when the cell temperature rises above the optimum temperature, the water content of the ion exchange membrane evaporates and the membrane resistance increases, and conversely, when the cell temperature falls below the optimum temperature, it was supplied to the cell. Moisture in the humidified fuel and humidified oxidant condenses to inhibit the electrode reaction, resulting in a marked decrease in battery performance. Therefore, it is necessary to generate the fuel cell at the optimum temperature. Therefore, conventionally, the temperature of the fuel cell has been controlled by arranging a special cooling plate for every tens to several cells and performing air cooling, water cooling or liquid cooling (cell manual, page 369).

However, when the cooling plates are arranged for every several tens to several cells, a temperature difference occurs between the central portion of the cell group sandwiched between the cooling plates and the cells which are in direct contact with the cooling plates. In order to solve these problems, a method of arranging a cooling plate every one cell or every three cells is proposed.

[0004]

However, when the cooling plates are arranged for each cell, the number of cooling plates is increased, so that the stacking height of the battery is increased, and when the cooling plates are arranged for every 3 cells, they are sandwiched between the cooling plates. In the cell that is in direct contact with the central portion and the cooling plate, a temperature difference of about 5 ° C. still occurs, which is not a complete solution for the temperature difference.

In view of the above circumstances, it is an object of the present invention to provide a fuel cell in which the cell temperature can be controlled to be constant and power can always be generated at an optimum temperature without increasing the cell stack height. And

[0006]

In order to solve the above problems, the present invention provides a fuel cell comprising a cell body and a reaction gas supply plate, in which cooling water is circulated on at least one surface of the reaction gas supply plate. The feature is that the groove for it is arranged.

[0007]

[Operation] At least one surface of the reaction gas supply plate,
Since the groove for circulating the cooling water (hereinafter, also referred to as “cooling water groove”) is arranged, the fuel cell can always generate power at the optimum temperature by controlling the circulation amount of the cooling water. Further, in a fuel cell using an ion exchange membrane, cooling water can be supplied to the ion exchange membrane by providing a cooling water groove in the reaction gas supply plate on the side that is in direct contact with the ion exchange membrane. The water content of can be controlled.

[0008]

EXAMPLES The present invention will be specifically described below with reference to examples. 1 is an exploded perspective view of a fuel cell using an ion exchange membrane according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA, FIG. 3 is a plan view of a cell body, and FIG. 4 is a bipolar plate. It is a top view.

As shown in FIG. 1, the fuel cell has an oxidant supply plate 1 (an example of a reaction gas supply plate) in the lowermost layer.
And the battery body 2 and the bipolar plate 3 (another example of the reaction gas supply plate) are alternately laminated on the uppermost layer, and the fuel gas supply plate 4 (reaction gas supply plate) is disposed on the uppermost layer. Still another example of the plate) is laminated.

As shown in FIG. 2, the battery main body 2 has a structure in which the electrode catalyst layers 6 and 66 are bonded to both surfaces of the ion exchange membrane 5. The electrode catalyst layers 6 and 66 are, for example, 0.5 mg / c of a mixture of 20 wt% platinum supported on carbon black and polytetrafluoroethylene (PTFE) mixed so that the PTFE content becomes 20 wt%.
It is produced by forming a sheet using a rolling roller so as to have m ² Pt. Then, the battery main body 2 prepares a pair of the electrode catalyst layers 6 and 66 thus obtained, and after applying a 5% Nafion solution (Aldrich Chemical Co.) to the surface thereof, these are subjected to an ion exchange membrane (Nafion 11
7, DuPont) 5, both sides, 200kg / c
It is prepared by hot pressing at m ² and 125 ° C. As shown in FIG. 3, the battery body 2 has an oxidant supply hole 7a, an oxidant discharge hole 7b, a fuel gas supply hole 8a, a fuel gas discharge hole 8b, a cooling water supply hole 9a and a cooling water discharge hole 9b. Are pierced respectively.

The bottommost oxidant supply plate 1 is shown in FIG.
As shown in FIG. 2, an oxidant supply groove 7 for supplying the oxidant to the electrode catalyst layer 66 and a cooling water groove 9 for supplying the cooling water to the ion exchange membrane 5 are arranged on the upper surface. Since the oxidant supply groove 7 and the cooling water groove 9 have the same structure as the upper surface of the bipolar plate 3, please refer to FIG. The oxidant supply groove 7 has substantially the same area as that of the electrode catalyst layer 66, and for example, six vertical grooves 71 and two grooves connected thereto are provided so that the oxidant can be uniformly supplied to the entire surface of the electrode catalyst layer 66. The horizontal groove 72. An oxidant supply hole 7a and an oxidant discharge hole 7b are respectively provided at two positions on the diagonal line of the oxidant supply groove 7 and communicate with the oxidant supply groove 7. The cooling water groove 9 is formed in a C shape so as to surround the oxidant supply groove 7, and cooling water supply holes 9a and cooling water discharge holes 9b are provided in the C-shaped cut portions, respectively.

As shown in FIG. 4, the bipolar plate 3 laminated between the battery main bodies 2 has an oxidant supply groove 7 and a cooling water groove 9 on its upper surface. The oxidant supply groove 7 and the cooling water groove 9 have been described in the section of the oxidant supply plate 1 and will be omitted here. On the other hand, a fuel gas supply groove 8 for supplying fuel gas to the electrode catalyst layer 6 and a cooling water groove 9 are arranged on the lower surface symmetrically with the upper surface (not shown). The fuel gas supply groove 8 is formed in the electrode catalyst layer 6
In order to supply the fuel gas uniformly over the entire surface of the electrode catalyst layer 6, it has, for example, six vertical grooves 81 and two horizontal grooves connected to the vertical grooves 81. A fuel gas supply hole 8a and a fuel gas discharge hole 8b are provided at two positions on the diagonal of the fuel gas supply groove 8 so as to penetrate therethrough,
It communicates with the fuel gas supply groove 8.

The uppermost fuel gas supply plate 4 has a fuel gas supply groove 8 and a cooling water groove 9 on the lower surface thereof, which are similar to those provided on the lower surface of the bipolar plate 3.
In addition, the oxidant supply plate 1, the bipolar plate 3,
Each hole (oxidant supply hole 7a, oxidant discharge hole 7b, fuel gas supply hole 8a, fuel gas discharge hole 8b, cooling water supply hole 9a, cooling water discharge hole 9b) provided in the fuel gas supply plate 4 and the cell body 2 ) Are provided so as to correspond to each other. However, the lower surface of the oxidant supply plate 1 is not penetrated by holes.

Next, the flow of fuel gas, oxidant and cooling water in the fuel cell constructed as described above will be explained. FIG. 5 is a schematic view of the flow of fuel gas in a cross section in a diagonal direction connecting the fuel gas supply hole and the fuel gas discharge hole, and FIG. 6 is a schematic view of flow of cooling water in a cross section of the fuel cell in the BB direction.

For example, when the fuel gas is fed from the fuel gas supply hole 8a of the uppermost fuel gas supply plate 4, as shown in FIG.
As indicated by the arrow, the fuel gas is supplied to the electrode catalyst layer 6 of the cell body 2 by flowing through the fuel gas supply groove 8, and is discharged to the outside of the cell through the fuel gas discharge hole 8b. On the other hand, when the oxidant is also sent from the oxidant supply hole 7a like the fuel gas, the oxidant flows through the oxidant supply groove 7 to supply the oxidant gas to the electrode catalyst layer 66 of the battery main body 2, and the oxidant discharge hole 7b. Through the battery (not shown).

Further, the uppermost fuel gas supply plate 4
When the cooling water is made to flow from the cooling water supply hole 9a of FIG. 6, it flows through the cooling water groove 9 as shown by the arrow in FIG. 6, and the cooling water is supplied to the ion exchange membrane 5 of the battery main body 2 from the upper surface and the lower surface to cool it. The water is discharged to the outside of the battery through the water discharge hole 9b. With this series of flows, the cell temperature of the fuel cell can be constantly controlled and the water content of the ion exchange membrane 5 can be appropriately controlled.

In this embodiment, the oxidant supply groove 7,
The fuel gas supply groove 8 and the cooling water groove 9 are formed on both surfaces of the bipolar plate 3, as shown in the sectional view of FIG. This is because the battery body 2 and the bipolar plate 3 are of a type in which a plurality of sheets are alternately laminated. FIG. 7 is a graph showing cell characteristics of a fuel cell according to an embodiment of the present invention and a conventional fuel cell.

In the figure, 10 is a graph showing the cell characteristics of a fuel cell using a conventional reaction gas supply plate having no cooling water groove. When the cell temperature rises from an optimum value, the internal resistance rises, and the cell performance increases. Drops sharply. Also, 1
As is clear from the graph of No. 1, when the battery temperature is lower than the optimum value, the characteristics on the high current density side are rapidly lowered due to the dew condensation of water, which hinders the diffusion of the reaction gas. On the other hand, 12 is a graph showing the cell characteristics of the fuel cell using the reaction gas supply plate according to one embodiment of the present invention, which is good because the cell temperature and the water content of the ion exchange membrane are appropriately controlled. Keeps good battery characteristics.

In the embodiment, the ion exchange membrane 5
Although the battery main body 2 using the above is used, the battery main body 2 using different types of the ion exchange membranes 5 can also be used. Further, although the cooling water groove 9 is arranged so as to surround the oxidant supply groove 7 and the fuel supply groove 8, in order to further enhance the cooling effect, the cooling water groove 9 is arranged in a meandering shape, and the contact area of the cooling water is increased. It is preferable to widen.

[0020]

As described above, according to the present invention, since the cooling water groove is arranged in the reaction gas supply plate, it is not necessary to dispose the cooling plate as in the conventional case, so that the stacking height of the battery is increased. Without controlling the battery temperature, the fuel cell can always generate power at the optimum temperature. Especially in a fuel cell using an ion exchange membrane,
Since the water-containing state of the ion exchange membrane can also be controlled appropriately, the effect of improving the battery characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a fuel cell according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of the fuel cell according to the embodiment of the present invention.

FIG. 3 is a plan view of a cell body in a fuel cell according to an embodiment of the present invention.

FIG. 4 is a plan view of a bipolar plate in a fuel cell according to an exemplary embodiment of the present invention.

FIG. 5 is a schematic diagram of the flow of fuel gas.

FIG. 6 is a schematic diagram of the flow of cooling water.

FIG. 7 is a graph showing cell characteristics of a fuel cell according to an embodiment of the present invention and a conventional fuel cell.

[Explanation of reference numerals] 1 oxidant supply plate 2 battery body 3 bipolar plate 4 fuel supply plate 9 cooling water groove 9a cooling water supply hole 9b cooling water discharge hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Saito 2-18 Keihan Hondori, Moriguchi City Sanyo Electric Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. A fuel cell comprising a cell body and a reaction gas supply plate, wherein a groove for circulating cooling water is arranged on at least one surface of the reaction gas supply plate. And a fuel cell.