JPS6041833B2 - Fuel cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fuel cells, particularly matrix oxygen, hydrogen fuel cells.

In general, a matrix type battery has a structure in which a gas separation plate 3 made of metal or graphite is interposed on the back side of gas diffusion electrodes 1 and 2 of different polarity to form respective gas chambers, as shown in FIG.

In addition, since the gas separation plate 3 is conductive, it functions as a connection part when connecting multiple cells, and the electrolyte matrix 4
The electrodes 1 and 2 and the electrodes and the gas separation plate 3 are brought into close contact with each other. However, active material gas such as oxygen or hydrogen flows into the recesses of the gas separation plate 3 and does not flow into the projections that are in contact with the electrodes.

Therefore, the electrode surface that actually acts is only the part facing the concave part of the gas separation plate, and the part in contact with the convex part does not participate in the reaction. For this reason, it is desirable to use a gas separation plate with wide recesses; however, when such a separation plate is used, there are few protrusions that make contact with the electrodes, which impairs the adhesion between the electrodes and the matrix, and the electrode surface deteriorates over long periods of use. deformation occurs, making it impossible to maintain the battery. Therefore, it is not possible to reduce the number of convex portions of the gas separation plate, and the electrode area in contact with these convex portions reaches 10 to 30% of the total area. Such a reduction in the effective area of the electrode reduces the electrode utilization rate and adversely affects the battery characteristics. The purpose of the present invention is to improve battery characteristics by minimizing the area of the electrodes that are not exposed to such reactions, and by interposing a conductive porous foam between the gas diffusion electrode and the gas separation plate. It is characterized by having

The conductive porous foam mentioned here has a porosity of 95 to 98%.
An example of an electrolyte-resistant metal with a pore size of 0 and 0.5 wn is stainless steel foam.

To explain the embodiment below, FIG. 2 shows a case where a gas separation plate 3 having uneven parts on both sides is used, and a layer made of the foamed material is interposed between this separation plate and each gas diffusion electrode 1, 2. 5,
5 are closely intervening.

In this case, gas is also supplied to the electrode surface corresponding to the convex portion of the gas separation plate through the foam layer 5, so the effective action area of the electrode increases and the foam layer 5 is brought into close contact with the entire surface of the electrode. Therefore, it is possible to securely hold the electrode and prevent its deformation. In the embodiment shown in FIG. 3, a thin metal plate 3'' is used instead of the uneven gas separation plate to separate gas, and a block-shaped plate is placed between the thin gas separation plate 3'' and each electrode 1, 2. This is the case where the foamed bodies 5'', 5'' are interposed.

In this case, the foam 5'' fills the space behind the electrode to form a gas chamber, and the conventional grooving of the gas separation plate is not required. Figure 4 shows the discharge characteristics of the fuel cell of the present invention for comparison. Therefore, the case of the conventional battery explained in FIG. 1 is shown by a dotted line.

As mentioned above, the present invention has a conductive porous material interposed between the back surface of the gas diffusion electrode and the gas separation plate, and this foam is pressed against the entire surface of the electrode to improve the adhesion between the electrode and the matrix. Furthermore, the electrode can be held reliably to prevent its deformation, and the reactive gas can be supplied to the entire surface of the electrode, increasing the effective working area of the electrode.

In addition, when using a gas separation plate with uneven parts on both sides, the layered foam is interposed between the protrusions and the reactive gas spreads to these parts, and the thin plate is used as the gas separation plate. If used, the gas chamber can also be formed by a block of foam.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of the main part of a conventional fuel cell, and FIGS. 2 and 3 are both enlarged sectional views of the main part of the fuel cell of the present invention. FIG. 4 shows the discharge characteristics of the fuel cell of the present invention. 1,2
...Gas diffusion electrode, 3,3"...Gas separation plate, 4...Matrix electrolyte, 5,5"
- Conductive porous foam.

Claims (1)

[Scope of Claims] 1. In a device in which a gas chamber is formed on the back surface of each electrode plate by a conductive gas separation plate interposed between gas diffusion electrodes of different polarities, the back surface of each electrode and the gas separation plate A fuel cell characterized in that an electrically conductive porous foam is interposed between the fuel cell and the fuel cell. 2. The gas separation plate has uneven parts on both sides, and the foam is configured as a layer that comes into contact with the protrusions of the separation plate and adheres to the back surface of the electrode. Fuel cell as described in Section. 3. The first aspect of claim 1, wherein the gas separation plate is made of a thin plate, and the foam is configured as a block that fills a space between the thin plate and the back surface of the electrode.
Fuel cell as described in Section.