JPH0227784B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas separation plate or electrode for a stacked fuel cell.

Conventionally, this type of gas separation plate is shown in Figures 1 and 2.
I got what is shown in the figure. FIGS. 1 and 2 are plan views of the fuel side and the oxidizer side, respectively. Note that the convex portions of the uneven portions on the plane are indicated by diagonal lines. The same applies to each figure below. In the case of an end plate, provide a groove as shown in either Figure 1 or Figure 2,
In the case of a double-grooved plate, the grooves shown in FIGS. 1 and 2 are provided on the front and back sides.

In FIG. 1, 1 is a fuel flow path, 2 is an external reservoir, and 3a, 3b, 3c, and 3d are supply holes used for electrolyte replenishment. 4 is the inflow channel of the fuel channel; 5
is the outflow channel. In FIG. 2, 6 is an oxidizing agent flow path, and 3a, 3b, 3c, and 3d are the above-mentioned supply holes used for electrolyte replenishment, which penetrate from the front surface to the back surface.

The fuel flow path and the oxidant flow path are provided in directions perpendicular to each other. 7 is an inlet flow path of an oxidizer flow path;
8 is an outflow channel. The lamination is achieved by inserting a non-conductive porous member impregnated with an electrolyte between the gas separation plates, and a fuel electrode and an oxidizer electrode with air permeability and water repellency sandwiching this member. It is done.

Next, the operation will be explained. reaction gas flow path 1,
The reaction gas supplied to 6 diffuses through the porous electrode and is ionized at the interface with the electrolyte-impregnated non-conductive porous member, and both ions react to form a compound. If the fuel is hydrogen, water is produced and current is generated at both electrodes. Current flows through the gas separation plate to the external circuit due to the electrical contact between the electrode and the protrusion 9. Furthermore, the electrolyte expands and contracts due to dilution with the water product and thermal cycles of the fuel cell. The external reservoir 2 is intended to alleviate this effect. Furthermore, since the electrolyte evaporates and disappears during long-term operation, electrolyte is replenished into the porous member through an external reservoir.
The supply holes 3a, 3b, 3c, and 3d are for this purpose.

Conventional gas separation plates were constructed as described above, and the reservoir was limited to the peripheral area. Therefore, a large electrode has the disadvantage that it is difficult to alleviate the expansion and contraction of the electrolyte in the central portion. Furthermore, the inlet/outlet of the fuel flow path and the inlet/outlet of the oxidizer flow path are distributed over the four sides of the gas separation plate, and there is a drawback that they cannot be centralized.

This invention was made to eliminate the above-mentioned drawbacks of the conventional method, and aims to eliminate both of the drawbacks of the conventional method at once by forming a reservoir in the Ω-shaped flow path and the recess of the Ω-shaped flow path. It is.

An embodiment of the present invention will be described below with reference to the drawings. FIGS. 3 and 4 are plan views of the gas separation plate of the present invention from the fuel side and the oxidizer side, respectively, and in order to show the positional relationship, the gas separation plate is shown projected from the same plane. In Fig. 3, 1 is a fuel flow path, 4 is its inflow path, 5 is its outflow path, and 2a and 2b are T-shaped and U-shaped external reservoirs, respectively, and these are the four sides of the gas separation plate. An external reservoir is provided in the section. 3a, 3b, . . . 3f are supply holes used for electrolyte replenishment, and 10 is a detour passage for equalizing the flow rate of the reaction gas. Further, in FIG. 4, 6 is an oxidizing agent channel, 7 is an inflow channel thereof, 8 is an outflow channel thereof, and 3a, 3b, . . . , 3f are supply holes 7 used for electrolyte replenishment.

The inlet of the inlet flow path 4 of the fuel flow path and the outlet of the outlet flow path 8 of the oxidizer flow path are located on the same side, but are separated at the center of the side and are located on the left and right sides, respectively. In addition, the outlet of the outflow channel 5 of the fuel channel and the inlet of the inflow channel 7 of the oxidizer channel are located on the same side, and their positions are separated at the center of the side and separated on the left and right sides, respectively. be. The fuel flow path 1 is approximately Ω when projected from one side.
A part of the T-shaped reservoir 2a is located in the recess of the Ω-shaped flow path. Further, the oxidant flow path 6 has a substantially approximate shape when projected from the above-mentioned surface.

Next, the operation will be explained. The reaction gas supplied to the reaction gas flow path diffuses into the porous electrode and is ionized at the interface with the electrolyte-impregnated non-conductive porous member, and both ions react to form a compound. . When the fuel is hydrogen, water is produced, but expansion and contraction due to dilution of the electrolyte with produced water and thermal cycles of the fuel cell are alleviated by external reservoirs provided in a T-shape and a U-shape.
In particular, since a part of the T-shaped external reservoir extends to the center, it is possible to adjust the amount of electrolyte in the center of the electrode. On the other hand, the current generated between both electrodes flows to the external circuit through the gas separation plate due to the electrical contact between the electrode and the convex part 9, but in the conventional case, the area where the surface pressure is applied to the electrode is about 50% of the convex part. %, or about 25% of the total area, whereas in this case, the electrical contact is greatly improved at about 75% of the protrusion curtain, or about 38% of the total area. Also, the external reservoir 2a,
Replenishment of electrolyte through 2b can also be carried out uniformly and quickly including the central part. The number of supply holes has also been increased to six to allow for faster electrolyte replenishment.

Also, as can be seen from Figures 3 and 4, the inlets and outlets of the reactant gas, that is, the fuel flow path and the oxidizer flow path, are concentrated on the two sides of the gas separation plate, so the manifolds connected to these flow paths are can be concentrated on two sides compared to the conventional four sides, and the extra sides can be used for arranging a cooling water manifold.

In the above embodiment, the external reservoir is provided on the fuel side, but it may be provided on the oxidant electrode side. Further, as shown in FIG. 5, the reaction gas flow path can have a streamlined corner portion to make the flow smooth. In the embodiment, four detour passages are provided for uniformizing the flow of the reaction gas, but the number of detour passages may be increased or decreased as necessary. Also,
The fuel inlet and fuel outlet may be reversed. ,
Also, the oxidant inlet and oxidant outlet may be reversed.

The external reservoir is a polygonal gas separation plate, usually rectangular, with two sides parallel to the inflow or outflow paths of the fuel flow path or oxidizer flow path, and a central portion extending from the sides. It is desirable to provide one. The provided external reservoirs may be separated from each other in any suitable shape, but it is preferable to provide an electrolyte supply hole for each separate external reservoir.

Furthermore, although the reservoir and the fuel or oxidant flow path are provided in the gas separation plate in the above example, the same effect can be expected even if the reservoir and the fuel or oxidant flow path are provided on the surface of the fuel electrode or oxidant electrode facing the gas separation plate.

As explained above, the present invention provides a flow of one of the fuel or the oxidizer so that the flow of the fuel or the oxidizer is approximately Ω-shaped when projected from one surface onto the opposing surface of the gas separation plate and one of the fuel electrodes or the oxidizer electrode. and forming an electrolyte reservoir in the recessed part of the Ω-shaped flow path, and at the same time, on the opposing surface of the gas separation plate and the other electrode of the fuel electrode or oxidizer electrode, projected from the one surface to form an approximate shape. Since the other flow path for the fuel or oxidizer is formed so that the expansion and contraction of the electrolyte at the center of the electrode can be alleviated, the outlet and inlet of the fuel flow path and the outlet and inlet of the oxidizer flow path can be It can be concentrated on two sides of the gas separation plate or electrode.

[Brief explanation of drawings]

Figure 1 is a plan view of the fuel side of a conventional gas separation plate.
Figure 2 is a plan view of the oxidizer side of a conventional gas separation plate.
FIG. 3 is a plan view of the fuel side of a gas separation plate according to an embodiment of the present invention, FIG. 4 is a plan view of the oxidizer side of a gas separation plate according to an embodiment of the invention, and FIG. FIG. 7 is a plan view of the fuel side of a gas separation plate according to another embodiment. In the figure, 1 is a fuel channel, 2, 2a, 2b are external reservoirs, 3a, 3b, ..., 3f are supply holes for electrolyte replenishment, 4 is an inflow channel of the fuel channel, 5 is an outflow channel,
6 is an oxidizer flow path, 7 is an inflow flow path of the oxidizer flow path, 8
9 is an outflow channel, 9 is a contact portion with the electrode, and 10 is a detour channel. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. In a stacked fuel cell in which a plurality of fuel electrodes, electrolyte matrices, oxidizer electrodes, and gas separation plates are sequentially stacked, the opposing surface of one of the fuel electrodes or oxidizer electrodes and the gas separation plate A flow path for either the fuel or the oxidant is formed in a substantially Ω-shape when projected from one side, and an electrolyte reservoir is formed in the recess of the Ω-shaped flow path. On the opposite surface of the other electrode and the gas separation plate,
A stacked fuel cell characterized in that the other flow path for the fuel or the oxidizer is formed so as to have an approximate shape when projected from the one surface. 2. The stacked fuel cell according to claim 1, wherein the reservoir is provided with an electrolyte supply hole.