JPH01186566A - Fuel cell - Google Patents

Abstract

PURPOSE:To sufficiently support electrodes and bring the gas into contact with the whole surfaces of the electrodes by arranging foaming metal plates with high porosity and small gas cavities all over the surfaces of the electrodes and inserting the foaming metal plates into gas passage forming recesses on the electrode side. CONSTITUTION:When the oxidation gas is fed to a cathode 2 side and the fuel gas is fed to an anode 3 side, the gas entering the gas passage 7 of a separator 4 is brought into contact with the cathode 2 and the anode 3 through foaming metal plates 8 because both the cathode 2 and the anode 3 are supported by the separator 4 via the plates 8 made of a foaming metal. At this time the foaming metal plates 8 have high porosity and generate a uniform gas flow on the whole surfaces, they have a sufficient size to be in contact with the whole surfaces of the cathode 2 and anode 3 electrodes, thereby the gas can be brought into uniform contact with the whole surfaces of the electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel cell used in the energy sector, which directly converts the chemical energy of fuel into electrical energy.

[Prior Art] Among the fuel cells that have been proposed to date, the molten carbonate fuel cell uses an electrolyte plate (tile) made by impregnating a porous material with molten carbonate, as shown in an example in Fig. 2. 1 is sandwiched between a cathode (oxygen electrode) 2 and an anode (fuel electrode) 3, and by supplying oxidizing gas to the cathode 2 side and supplying fuel gas to the anode 3 side, the connection between the cathode 2 and anode 3 is achieved. It is known that one cell (2) is configured to generate electricity by the potential difference generated between the cells, and each cell is laminated in multiple layers with a separator 4 in between.

In the separator 4, gas flow paths 5 are formed by recesses and recesses on both the front and back surfaces of the central portion excluding the peripheral portion, to allow different gases to flow to the cathode 2 side and the anode 3 side, respectively. The fuel cells are stacked so that the electrodes are located in the flow path 5, and different gases are flowed on both sides of the separator 4, so that the gas flows through the gas flow path 5 toward the cathode 2 side and the anode 3 side. .

It is advantageous if the gas flow path 5 formed by the unevenness formed on both the front and back surfaces of the separator 4 is formed by providing a large number of small grooves, since the electrodes will be supported sufficiently. Securing a flow path is a problem and manufacturing is difficult. Therefore, conventionally, as shown in FIG. 3, wide grooves are formed at a wide pitch, and eight grooves are formed into flow paths 5a having a rectangular cross section.

However, if the groove width of the gas flow path of the separator 4 is increased, a part of the electrode may sag in the gas flow path, resulting in incomplete support of the electrode.

For this purpose, conventionally, a punch plate 6 is used to be interposed between each of the cathode 2 and anode 3 electrodes and the separator 4.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional fuel cell, from the viewpoint of securing a flow path and manufacturing efficiency, the flow paths formed on both sides of the separator 4 are enlarged and the punch plate 6 is used. As a result, the gas flow path 5a of the separator 4 comes into contact with the electrode via the punch plate 6, creating a portion where the gas does not come into contact with the electrode, degrading the performance of the fuel cell.

Therefore, the present invention aims to provide sufficient support for the electrode and to allow gas to come in contact with the entire surface of the electrode.

[Means for Solving the Problems] In order to achieve the above object, the present invention sandwiches an electrolyte plate between a cathode and an anode from both sides, and supplies oxidizing gas to the cathode side and fuel gas to the anode side. A foamed metal plate with high porosity and small pores is placed over the entire surface of each electrode of the fuel cell to be supplied.
Further, the foamed metal plate is fitted into a gas flow path forming recess on each electrode side.

[Function] Foamed metal has air permeability, allowing gas to flow through it easily, and has small pores, so it can support electrodes over its entire surface. This makes it possible to realize a uniform flow of gas over the entire surface of the electrode, allowing the gas to come into uniform contact with the electrode, thereby improving performance.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a fuel cell stack is constructed by stacking cells in which both sides of an electrolyte plate 1 are sandwiched between a cathode 2 and an anode 3 with a separator 4 in between. In this method, recesses that will become the gas flow paths 7 are formed on both sides of the center portion of the separator 4 where the cathode 2 and the anode 3 are located, and the recesses that will become the gas flow paths 7 on both sides have high porosity and pores. For example, a foamed metal plate 8 such as pumice with a small diameter is inserted so that it is in direct contact with the cathode 2 and anode 3 electrodes, and the electrodes are pressed against the electrolyte plate 1 through the foamed metal plate 8. Make it.

When oxidizing gas is flowed to the cathode 2 side of a fuel cell partitioned by a separator 4, and fuel gas is flowed to the anode 3 side, both the cathode 2 and the anode 3 pass through the separator 4 through the plate 8 made of foam metal. Therefore, the gas entering the gas flow path 7 of the separator 4 comes into contact with the cathode 2 and the anode 3 through the foamed metal plate 8. At this time, the foamed metal plate 8 has a high porosity and is designed to generate a uniform gas flow over the entire surface, and the foamed metal plate 8 covers the entire surface of each electrode of the cathode 2 and anode 3. Since the electrodes are large enough to touch each other, the gas can uniformly touch the entire surface of the electrode. This makes it possible to generate electricity over the entire surface of the electrode, improving fuel cell performance.

In addition, in the above embodiment, the fuel cells were stacked with separators in between, but the same applies even if the gas flow path is formed of something other than separators, for example, upper and lower holders. Applicable.

[Effects of the Invention 1] As described above, according to the fuel cell of the present invention, a foamed metal plate with high porosity and small pores is arranged in the flow path of gas supplied to each of the cathode and anode electrodes. In addition, since the foamed metal plate is sized to cover the entire surface of the electrode, and the gas flow path portion only needs to be formed with a recess into which the foamed metal plate is inserted, manufacturing of the gas flow path portion is facilitated. At the same time, since the pores of the foam metal plate are small, the entire surface is in the same state as receiving the electrode, and the electrode is completely supported.Also, the high porosity of the foam metal plate allows for uniform gas flow over the entire surface. Excellent effects such as flow can be realized and the electrode can come into contact with the gas uniformly can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the fuel cell of the present invention;
The figure is a sectional view showing an example of a conventional fuel cell, and FIG. 3 is a sectional view showing an electrode support state in a conventional fuel cell when the gas flow path is large. DESCRIPTION OF SYMBOLS 1... Electrolyte plate, 2... Cathode, 3... Anode, 4... Separator, 5.5a, T... Gas flow path, 8... Foamed metal plate. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1) An electrolyte plate is sandwiched between the cathode and anode electrodes, and oxidation gas is supplied to the cathode side, and fuel gas is supplied to the anode side.The porosity of each electrode surface is adjusted to A fuel cell characterized in that tall pumice-like foamed metal plates with small pores are arranged in contact with each other over the entire surface, and the foamed metal plates are fitted into gas flow path forming recesses on each electrode side. .