JPS6240826B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel cell having a stacked structure in which a large number of unit cells are stacked, and which connects the fuel electrodes and oxidizer electrodes of adjacent unit cells, or the fuel electrodes and oxidizer electrodes of adjacent unit cells. , and relates to a structure for efficiently extracting electricity from a fuel electrode and an oxidizer electrode.

A fuel cell is a type of DC generator that can continuously generate electricity by supplying fuel to a fuel electrode and an oxidant to an oxidizer electrode. The unit cell that constitutes the power generation section consists of a fuel electrode, an oxidizer electrode, an electrolyte chamber, a fuel chamber, and an oxidizer chamber, which are connected in series or in parallel depending on the electrical output. When fuel cells generate electricity, electrical losses occur due to various polarization phenomena, but apart from these, electrical losses also occur when extracting electricity from each electrode to the outside or when connecting the electrodes of adjacent cells. occurs. When all of these are converted into heat and accumulated, the temperature of the stacked battery increases, causing thermal distortion of the electrodes, separators, etc. Loss due to polarization phenomenon is caused by a decrease in the active ability of the catalyst, insufficient supply of fuel and oxidizer, factors that impede ionic conductivity, etc.A large reaction interface can be obtained by developing catalysts and improving the internal structure of electrodes. Efforts are being made to develop such electrodes.

On the other hand, the electrical loss when extracting electricity from each electrode or when connecting the electrodes of adjacent cells is
This is caused by pure electrical resistance, and making this extremely small is also important for improving thermal efficiency and reducing size and weight.

The present invention relates to a separator that solves the problem of loss caused by pure electrical resistance, and one embodiment of the present invention will be described below in comparison with a conventional fuel cell.

Figure 1 shows that metal terminals for current collection are attached around each electrode, and these terminals are taken out to the outside of the stacked battery.
This figure shows a battery with a conventional electrical connection structure that connects the electrodes of adjacent single cells. As mentioned above, each cell is composed of an oxidizer electrode 1, a fuel electrode 2, an electrolyte chamber 3, an oxidizer chamber 5, and a fuel chamber 6. They are laminated with a separator 4 interposed therebetween to form a chamber 6. Electrical connection terminals 9 for current collection are welded to each electrode 1, 2, and these are taken out to the outside of the stacked battery to electrically connect adjacent unit cells. Figure 2 shows that a third electrode is placed around the oxidizer electrode 1 shown in Figure 1.
The figure shows an electrical connection terminal 9 welded and attached to one side of the oxidizer electrode 1 shown in FIG. 1 as well. In such conventional fuel cells, electricity generated at the center of the electrode in the case of the electrode structure shown in FIG. 2 and at the bottom of the electrode in the case of the electrode structure shown in FIG. This caused thermal distortion of electrodes, separators, etc., as it was converted into heat by the resistance of the metal. In contrast, FIG. 4 shows the present invention in which single cells are stacked via a separator 4a having an electrical connection piece 10 and whose surface forming an oxidizer chamber and a fuel chamber is coated with an electrically conductive material 11. This shows a fuel cell in one embodiment, in which the electrode surfaces of an oxidizer electrode 1 and a fuel electrode 2 are in contact with each other via an electrical connection piece 10 in a stacked state of the single cells. The configuration of the cell is the same as in Figure 1, but
An electrical connection piece 10 is fixed to the separator 4a, and the surface forming the oxidizer chamber and fuel chamber is coated with an electrically conductive material 11, and the battery connection piece 10 and the electrically conductive material 11 are connected. It is becoming a state. In addition, in FIGS. 1 and 4, 7 is an electrolyte supply passage, and 8 is an electrolyte discharge passage. FIG. 5 shows the separator 4a for the electrodes in FIG. 4 having effective dimensions of 200 mm x 300 mm, to which 15 electrical connection pieces 10 are fixed and further covered with a 0.1 mm thick nickel plate. The number of electrical connection pieces 10 and the thickness of electrically conductive material 11 can be freely selected depending on the size of the electrode area and current density. 6th
The figure shows the current density-average unit current density of a hydrogen-oxygen fuel cell using a 600 cm ^2- electrode battery with a conventional connection structure and a separator 4a with 15 electrical connection pieces 10 of the present invention fixed and covered with an electrically conductive material 11. This is the battery voltage characteristic. In each case, the performance of a fuel cell made of a stacked battery consisting of six single cells stacked is shown. Although nickel was used as the material for the electrical connection piece 10, almost the same performance could be obtained using an elastic material such as silicone rubber doped with silver. By using the separator 4a having the electrical connection piece 10 of the present invention and covered with the electrically conductive material 11, a current density of 100 mA/
The cell voltage has improved by about 32 mV at cm ² and about 50 mV at 200 mA/cm ² . Furthermore, thermal distortion of electrodes, separators, etc., which was a problem in the past, no longer occurs. By selecting the materials of the electrically conductive material 11 and the electrical connection piece 10, you can choose not only the hydrogen-oxygen type using an alkaline electrolyte, but also the hydrogen-air type using a liquid fuel cell such as a hydrazine-air type or an acidic electrolyte. It can also be applied to fuel cells such as

As described above, according to the present invention, the conventional problem of heat loss caused by electrical resistance is solved, the battery performance is improved, a small and lightweight fuel cell is obtained, and the manufacturing and assembly are easy. Since it has the advantage of being easily produced, its industrial value is great.

[Brief explanation of the drawing]

Figure 1 is a schematic explanatory diagram of a fuel cell with a conventional electrical connection structure, Figure 2 is a front view of the oxidizer electrode used in Figure 1 with electrical connection terminals welded around the entire circumference, and Figure 3 is the FIG. 4 is a front view showing an electrical connection terminal welded to one side of the oxidizing agent electrode used in the figure. A schematic explanatory diagram of a fuel cell in which unit cells are stacked. Figure 5 is a front view of a separator in which 15 electrical connection pieces in this embodiment are fixed and is further covered with an electrically conductive material. Figure 6 is a diagram of a conventional fuel cell. FIG. 4 is a comparison curve diagram of current density-average cell voltage characteristics between the fuel cell shown in FIG. 1 is an oxidizer electrode, 2 is a fuel electrode, 4a is a separator, 5 is an oxidizer chamber, 6 is a fuel chamber, 10 is an electrical connection piece, and 11 is an electrically conductive material.

Claims (1)

[Claims] 1. A unit cell having an oxidizer electrode and a fuel electrode arranged opposite to each other and an electrolyte located between the two electrodes is provided with an oxidizer chamber that supplies an oxidizer to the oxidizer electrode and a fuel electrode that supplies fuel to the fuel electrode. An electrical connection piece for electrically connecting an oxidizer electrode and a fuel electrode to the separator in a fuel cell in which a large number of fuel cells are stacked with separators formed with fuel chambers facing each other on both sides. 1. A fuel cell characterized in that the surface of the separator on which the oxidizer chamber and the fuel chamber are formed is coated with an electrically conductive material so as to be connected to an electrical connection piece. 2. The fuel cell according to claim 1, wherein the material covering the electrical connection piece and the separator is made of a metal material. 3. The fuel cell according to claim 1, wherein the material covering the electrical connection piece and the separator is made of a conductive resin or a conductive elastic material.