JPS5943649Y2 - gas diffusion electrode - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a gas diffusion electrode in a fuel cell in which fuel and oxygen (or air) are continuously supplied from the outside and are electrochemically reacted to extract electrical energy.

FIG. 1 is a diagram explaining the principle of a hydrogen-oxygen fuel cell.

In the figure, an electrolyte chamber 1 is formed by the opposing surfaces of the hydrogen electrode 2 and the oxygen electrode 3, a hydrogen gas chamber 4 is formed on the other surface of the hydrogen electrode 2, and an oxygen gas chamber is formed on the other surface of the oxygen electrode 3. 5 is provided.

6 is a load connected to the hydrogen electrode 2 and the oxygen electrode 3.

The electrolyte in the electrolyte chamber 1 includes an alkaline aqueous solution such as caustic potash or an acidic aqueous solution such as sulfuric acid.

The hydrogen electrode 2 and the oxygen electrode 3 are made of porous metal, activated carbon, etc. as a base material, platinum, palladium, etc. as a catalyst, and polytetrafluoroethylene (trade name: Teflon), polyethylene, etc. as a binder. It was sintered and fastened into a thin plate with many pores about 0.15 to 0.8 van in thickness.

In addition, these electrodes 2 and 3 adjust the amount of binder to create a repellent layer between the water-repellent layer that prevents the electrolyte from leaking to the gas side and the hydrophilic layer that is wetted by the electrolyte. It is formed from a catalyst layer existing between an aqueous layer and a hydrophilic layer.

Generally, the output voltage of a single cell is approximately IV, and the output current density is several hundred m
Since the voltage is about lv'c4, in order to obtain the required voltage and current, a plurality of these single cells are stacked to form a block, and the blocks are further connected to form a fuel cell.

Therefore, the electricity generated by the electrodes needs to be collected as simply and efficiently as possible.

For this purpose, a method is known in which a conductive current collector plate having protrusions is pressure-bonded to the gas-side electrode surface to collect current.

According to this method, when stacking unit cells, it is possible to internally connect them in series simply by stacking the unit cells.

However, in order to improve water repellency, a large amount of polytetrafluoroethylene is used as a water repellent, or a porous fluoride resin sheet is sometimes attached to the surface of the electrode 2゜3 on the gas chamber side. .

For this reason, the electrical resistance of this surface becomes extremely high, and even if a current collector plate is crimped to this surface, sufficient current collection cannot be obtained. Furthermore, since the current collector plates having protrusions on their surfaces are in direct contact with each other, there is a problem in that gas diffusion in the press-bonded portions of the electrodes 2 and 3 is poor, resulting in a decrease in electrode performance.

For this reason, it is not possible to adopt a current collection method using a series connection inside the cell, and the electrodes 2 and 3 are each provided with a current collection terminal, which is taken out to the outside of the cell and connected in series. The drawback was that it was complicated.

In view of the above points, the present invention eliminates the drawbacks of the conventional technology, improves the current collection effect by the current collector plate, simplifies the configuration, and achieves sufficient gas diffusion between the current collector plate and the electrode. The object of the present invention is to provide a gas diffusion electrode that can maintain electrode performance over a long period of time.

According to the present invention, this purpose is achieved by a gas diffusion electrode for fuel cells formed by stacking a plurality of unit cells each having an electrode and a gas chamber and an electrolyte chamber that are in contact with each other through the electrode. a mesh-like metal current collecting member configured integrally with the electrode and having a folded part folded back toward the gas chamber; a metal current collector plate that is crimped to the folded part of the metal current collector member by a protrusion and collects current; the folded part of the metal current collector member is provided between the electrode and the metal current collector plate; This is achieved by creating a gap through which the gas is diffused.

Next, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 shows a schematic configuration diagram of an embodiment of the present invention, A is a front view thereof, B is a side view thereof, and FIG. 3 is a schematic diagram of the configuration in the usage state shown in FIG. 2.

In FIG. 2, a rectangular metal current collecting member, in this embodiment a wire mesh 11, is a current collecting material for the electrode 7 and also serves as a reinforcing material.

A square electrode portion 10 consisting of a water-repellent layer 8 serving as a gas side layer and a catalyst layer/hydrophilic layer 9 on the other side is integrally sintered on one side of the central portion of the wire mesh 11.

The upper and lower parts of this wire mesh 11 are folded back to the gas side layer 80 surface, as shown in FIG. 2, to form a folded part 12 on almost the entire surface of the gas side layer.

Although the folded portion 12 is provided on almost the entire surface of the electrode portion 10 in this embodiment, the folded portion 12 is not limited to this, and it is also possible to form the folded portion partially.

Next, FIG. 4 shows a schematic diagram of the fuel cell according to the embodiment of the present invention shown in FIG.

In the figures, parts having the same functions as those in FIGS. 1 and 3 are given the same reference numerals.

13 is a metal current collector plate having protrusions, 14 is a cell frame that supports the electrode 7, 15 is a cell frame at both ends of the fuel cell, 16
are current collecting terminals connected to current collecting plates 13 at both ends of the fuel cell.

These plurality of electrodes 7 are connected to a plurality of cell frames 14 and 15.
Together, a plurality of electrolysis chambers 1, a hydrogen gas chamber 4, and an oxygen gas chamber 5 are formed, and each gas chamber 4, 5 is interposed with a plurality of current collector plates 13 that are crimped to the electrodes 7 to collect current. and constitute a stacked structure fuel cell.

The functions of the present invention having the above-mentioned configuration will be explained.

The electrically conductive metal current collector plate 13 is crimped to the metal mesh folded part 12 of the electrode 7 by projections formed on both sides of the current collector plate 13 to collect current.

Therefore, this fuel cell does not require current collecting terminals for connecting the plurality of electrodes 7 in series, and can be internally connected in series by simply stacking a plurality of unit cells.

Note that in this embodiment, the current collector plate 13 does not directly contact the gas side layer of the electrode 7, but the folded part 12 made of wire mesh is interposed between the current collector plate 13 and the electrode 7, so that the protrusion of the current collector plate 13 part and electrode 7
A gap is created between the two.

Therefore, the diffusion of gas on the surface of the electrode 7 is not inhibited.

Next, FIG. 5 is a schematic configuration diagram of another embodiment of the present invention, and FIG.
The figure shows a schematic diagram of the configuration in the usage state of FIG. 5.

In FIG. 5, in the electrode 17, a square electrode portion 19 is integrally sintered at the center of a square wire mesh 18.

The four corners of the wire mesh 18 are folded back as shown in FIG. 6 to form a folded part 20 on almost the entire surface of the gas side layer of the electrode part 19.

Similar to the electrode 7 in FIG. 4, this electrode 17 is internally connected in series with the current collecting plate 13 and the cell frame 14, 15 to constitute a fuel cell.

Although the folded portion 20 is provided on almost the entire surface of the electrode portion 19 in this embodiment, the folded portion 20 is not limited to this.
It is also possible to form a partially folded portion.

As explained above, according to the present invention, a wire mesh serving as an electrode reinforcing material and a current collector is folded back to the gas side layer surface to form a folded part, and a current collecting plate having a protrusion is crimped onto this folded part. , the current collection effect is improved without using a special current collection connection, and (2) the protrusions of the current collection plate do not come into direct contact with the water-repellent layer surface of the gas diffusion electrode, and a wire mesh is interposed between them. This has the effect that gas diffusion on the electrode surface is not inhibited.

Note that although the mesh-like metal current collecting member is a wire mesh in this embodiment, it is not limited to this, and an expanded metal or the like may be used.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of a fuel cell, Fig. 2 is a schematic diagram of an embodiment of the present invention, A is a front view thereof, B is a side view thereof, and Fig. 3 is a diagram showing the state of use shown in Fig. 2. 4 is a schematic diagram of a fuel cell according to an embodiment of the present invention in FIG. 3; FIG. 5 is a schematic diagram of another embodiment of the present invention; FIG. 6 is a diagram showing the use of FIG. It is a schematic block diagram in a state. 7.17... Electrode, 10.19... Electrode part, 11.18... Wire mesh, 12.20...
... Folded part, 13... Current collector plate, 14.15
...Cell frame, 16...Current collector terminal.

Claims (1)

[Scope of utility model registration request] A gas diffusion electrode for a fuel cell formed by stacking a plurality of unit cells each having an electrode and a gas chamber and an electrolyte chamber in contact with each other via the electrode, the gas diffusion electrode being integrally formed with the electrode. a mesh-like metal current collecting member having a folded part folded back toward the gas chamber side; and a mesh-like metal current collecting member provided in the gas chamber and having a protrusion on its surface and crimped to the folded part of the metal current collecting member by the protrusion. What is claimed is: 1. A gas diffusion electrode comprising: a metal current collector plate made of metal, and a gap through which gas is diffused between the electrode and the metal current collector plate.