JPH0320863B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel cell in which an electrolytic solution can be supplied to an electrolyte layer from a separator side.

Normally, a fuel cell is constructed by stacking a plurality of fuel cells, each consisting of a porous fuel electrode and an oxidation electrode, and an electrolyte layer containing an electrolyte such as phosphoric acid between these two electrodes, with a separator interposed between them. The battery body is constructed by arranging a cooling device and tightening them together.

Each electrode of the battery body is arranged so that one side is in contact with the gas passage and the other side faces the electrolyte layer via the catalyst layer, and the gas passage that each electrode of the battery body is in contact with As a means of supplying and discharging fuel gas (hydrogen) and oxidizing gas (air), a manifold is fixed to the side of the battery body.
Oxidizing gas or fuel gas is supplied and discharged from the electrodes of each unit cell all at once.

When hydrogen, which is a fuel gas, flows through the gas passage, the hydrogen reaches the boundary surface of the electrolyte layer through the porous fuel electrode and catalyst layer. Here, an electrochemical reaction takes place, hydrogen is ionized and transported by the electrolyte, and likewise the oxidizing gas (air) at the interface of the catalyst layer.
reacts. Fuel cells use such electrochemical reactions to generate electricity. Therefore, retaining a sufficient amount of electrolyte in the electrolyte layer is an important point for extending the life of the battery.

In such fuel cells, the electrolyte in the electrolyte layer passes through the catalyst layer and electrodes and is carried away into the fuel gas and oxidizing gas and gradually disappears, making it impossible to maintain the initial performance of the fuel cell for a long period of time, resulting in a shortened service life. But it has shortcomings.

Therefore, as methods for replenishing the electrolyte in the electrolyte layer that disappears during operation, there are two methods: pre-filling each electrode with replenishing electrolyte, and installing an electrolyte replenishing device outside the battery body. Several methods have been proposed for supplying this information. In the former method, the electrolyte can be almost uniformly dispersed within the electrolyte layer, but there is a problem that the amount of electrolyte that can be stored is limited, and in the latter method, the amount of electrolyte stored and supplied is limited to the amount consumed. can do much more than
There are difficulties in uniformly distributing the supply to the electrolyte layer.

An object of the present invention is to provide a fuel cell that can effectively replenish electrolyte, maintain initial performance for a long period of time, and extend its life.

A feature of the fuel cell of the present invention is that when unit cells are stacked with an electrolyte layer containing an electrolytic solution between the fuel and oxidation electrodes, one side of which is in contact with a gas passage, the separator is electrolyzed. A liquid supply groove is provided, and a through hole is provided for supplying the electrolyte from the electrolyte supply groove to the electrolyte layer via the electrode,
Further, an electrolytic solution holding tank is provided above the manifold, and the electrolytic solution holding tank is communicated with the electrolytic solution supply groove.

Hereinafter, each embodiment of the fuel cell of the present invention will be described in order using FIGS. 1 to 6.

The fuel cell shown in FIG. 1, which is an example of the fuel cell of the present invention, has a flat fuel electrode 1 whose one side is in contact with a gas passage 3 for fuel gas, and a flat plate-shaped fuel electrode 1 whose one side is in contact with a gas passage 4 for air, which is an oxidizing gas. A battery body is constructed by stacking a plurality of unit cells each having an electrolyte layer 5 for holding an electrolyte such as phosphoric acid between the air electrode 2 and the air electrode 2 with a separator 6 in between to prevent the fuel gas and air from mixing. It consists of

Separator 6 for separating fuel gas and oxidizing gas
For example, a carbon plate impregnated with phenol resin or the like to make it dense is used to prevent gas from passing through, and since this separator 6 is combined with each of the flat electrodes 1 and 2, it is formed as described below according to the present invention. Ru. In addition, both flat electrodes 1 and 2 are provided with catalyst layers 11 and 12 on the surface opposite to the gas passage side, or with an electrolyte layer 5 on the surface.
Therefore, an electrolyte layer 5 for holding an electrolytic solution is installed between the catalyst layers. Furthermore, the gas passages 3 and 4 which are in contact with both electrodes 1 and 2 are orthogonal to each other to form a unit cell.

A manifold (not shown) is fixed to the side surface of the stacked battery body as a means for supplying and discharging fuel and oxidizing gas, and the fuel and oxidizing gas are passed through the gas passages of each unit cell to generate electricity.

Separator 6 combined with each flat electrode 1, 2
As shown in FIGS. 1 and 2, the electrodes 1 and 2 are partitioned by a plurality of ribs 7 on the surface thereof, and are formed as a so-called ribbed separator having gas passages 3 and 4 orthogonal to each other on both surfaces. There is. Furthermore, an electrolytic solution supply groove 8 is provided outside the gas passage 4 of the separator 6 over the entire width of the separator so as to intersect with the gas passage 3 on the fuel electrode 1 side. A plurality of through holes 9 are provided to allow the electrolytic solution to flow toward the ribs 7 on the side, and the electrolytic solution supplied from the through holes 9 is widely dispersed over the surface of the fuel electrode 1 on the surface of the rib 7 on the side of the fuel electrode 1. Therefore, the dispersion groove 10 is formed.

Therefore, if an electrolyte supply device (not shown) is connected to the electrolyte supply groove 8, the electrolyte will flow as shown by the arrow, flow down through the through hole 9, and reach the fuel electrode 1 side. The electrolyte layer 5 is replenished via the fuel electrode 1 and the catalyst layer 11, and replenishment can also be expected from the oxidation electrode 2 side by capillary action.

Therefore, even if the electrolyte in the electrolyte layer 5 gradually disappears during operation of the fuel cell, it can be replenished at any time from the electrolyte supply groove 8 connected to an external replenishment device, without deteriorating the battery performance. It can operate stably for a long period of time.

In the above example, the electrolyte supply groove 8 was provided on the outside of the gas passage 4 provided in the separator 6, but this is provided in the gas passage 3 on the surface in contact with the fuel electrode 1.
It can also be provided outside the tank to replenish the electrolyte.
Furthermore, although the dispersion grooves 10 formed on the surface of the rib 7 are shown as continuous grooves, they may be dispersed grooves connected to the respective electrolyte supply grooves 8, or the dispersion grooves 10 formed on the surface of the rib 7 may be dispersed through the porous electrodes. It is not necessary to provide this when sufficient dispersion can be expected. Furthermore, one or more electrolyte supply grooves 8 are provided in consideration of replenishment of electrolyte to the electrolyte layer 5.

A fuel cell shown in FIGS. 3 and 4, which is another embodiment of the present invention, uses a so-called ribbed electrode having gas passages 3 and 4 separated by ribs as a fuel electrode 1 and an oxidation electrode 2. , to which the electrolyte supply groove 8
This embodiment is a combination of a flat separator 6 provided with through holes 9 and dispersion grooves 10, and other points are similar to the embodiments described above. This separator 6
The electrolytic solution supply groove 8 and the like provided in the can be appropriately changed and provided as described above.

In this embodiment as well, the same effects as in the examples shown in FIGS. 1 and 2 can be achieved, and the structure of the separator 6 can be simplified.

An example of a structure for replenishing the electrolyte solution into the electrolyte supply groove 8 of the separator 6 is shown in FIGS. 5 and 6. In the example shown in FIG. 5, an electrolytic solution holding tank 14 is formed in a manifold 13 attached to the side surface of the battery body, and this electrolytic solution holding tank 14 and an electrolytic solution supply groove 8 are communicated to supply electrolytic solution. In the case shown in Fig. 6, an electrolyte holding tank 16 is formed in the holder 15 of the cooling device arranged for each unit battery, and is formed on the electrodes and separators of each unit battery so that they are continuous. Through the connecting hole 17,
The electrolytic solution is supplied to the electrolytic solution supply groove 8.

The replenishment of the electrolytic solution to the electrolytic solution supply groove 8 is not limited to the above-mentioned structural examples, and various structures can be applied.

If a fuel cell is configured as in the present invention, a sufficient amount of electrolyte can be supplied to the electrolyte layer disposed between the fuel and oxidation electrodes, so the initial performance of the battery can be maintained for a long period of time, and the battery life can be significantly extended. There is an effect that can be done.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional perspective view of a fuel cell that is an embodiment of the present invention, FIG. 2 is a partially sectional perspective view of the separator used in FIG. 1, and FIG. FIG. 4 is a partially cross-sectional perspective view of a fuel cell according to another embodiment of the invention, FIG. 4 is a partially cross-sectional perspective view of the separator used in FIG. 3, and FIGS. 5 and 6 are different from each other. FIG. 2 is a perspective view showing an electrolyte supply structure of a fuel cell. 1... Fuel electrode, 2... Oxidation electrode, 3, 4...
gas passage, 5... electrolyte layer, 6... separator,
7... Rib, 8... Electrolyte supply groove, 9... Through hole, 10... Dispersion groove, 11, 12... Catalyst layer.

Claims (1)

[Claims] 1. Unit cells in which an electrolyte layer containing an electrolytic solution is arranged between a fuel electrode and an oxidation electrode whose one side is in contact with a gas passage are stacked with a separator interposed therebetween, and the side of the stacked body In the separator having a manifold, on the upper surface of the separator and near the end surface,
An electrolyte supply groove is provided, a through hole is provided for supplying the electrolyte from the electrolyte supply groove to the electrode layer via the electrode, and an electrolyte holding tank is provided in the upper part of the manifold to hold the electrolyte. A fuel cell characterized in that a tank and the electrolyte supply groove are communicated with each other. 2. The fuel cell according to claim 1, wherein each of the electrodes is formed into a flat plate shape, and the separator has a gas passage defined by a plurality of ribs. 3. Claim 1 is characterized in that each of the electrodes has a flat side surface of the electrolyte layer and a gas passage defined by a plurality of ribs on the side surface of the separator, and the separator is formed in a flat shape. fuel cell.