JPS61193376A - Fuel cell - Google Patents

Abstract

PURPOSE:To improve reliability of the captioned cell while eliminating contact of a laminated cell with a bus bar by providing a flexible spring structure part in the course of a bus bar so as to release a stress generated in heat cycle, when clamping the laminated cell by holding it with a current collector plate and connecting said bus bar to the current lead terminal of the current collector plate. CONSTITUTION:A matrix for holding electrolyte is disposed between a pair of gas diffusion electrodes having a flow path for air being an oxidizing gas and a flow path for hydrogen being fuel gas, and a plurality of unit cells yielded as such are laminated to provide laminated cell 11. Then, current collector plates 2 are mounted on the top and bottom faces of the cell 1 and clamped with a metal clamping fitting 3, and a copper bus bar 6 is fixedly mounted on a current lead terminal 5 projecting from the current collector plate 2 by making use of a clamping bolt 7. In succession, the bar 6 is bent downwardly and fixedly mounted on a manifold 4 serving to supply or exhaust gas and provided on the side wall of the cell 1 with use of an insulating and heat resistant support 9. Thereupon, a spring structure part 8 is provided in the course of the bar 6 for absorbing thermal expansion upon heat cycle.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a fuel cell, and particularly to bending that occurs at the connection between a current wire and a current extraction terminal of a current collector plate, which occurs during a heat cycle when starting and stopping battery operation. The present invention relates to a fuel cell capable of relieving stress.

[Technical Background of the Invention] Fuel cells are conventionally known as devices that directly convert energy contained in fuel into electrical energy. This fuel cell usually includes a pair of gas diffusion electrodes sandwiching an electrolyte, and a fuel gas such as hydrogen is brought into contact with the back surface of one electrode, and an oxidizing gas such as oxygen is brought into contact with the back surface of the other electrode. By utilizing the electrochemical reaction that occurs at this time, electrical energy can be extracted from between the electrodes.

FIG. 3 is a partial vertical sectional view showing the structure of a conventional fuel cell of this type. In the figure, 1 is a stacked cell, which is a unit cell consisting of a matrix that holds an electrolyte between a pair of gas diffusion electrodes, which has a flow path for air, which is an oxidant gas, and a flow path for hydrogen, which is a fuel gas. It is formed by laminating multiple pieces.

In addition, this laminated cell 1 has current extraction terminals 5 on its upper and lower sides.
The fuel cell main body is formed by sandwiching the current collecting plates 2 between them, and further tightening and fixing them in the stacking direction using fastening metal fittings 3 placed above and below the current collecting plates 2. Furthermore, a manifold 4 is fixed to the side of the fuel cell body to supply and exhaust air and hydrogen to and from the stacked fuel cell body, so that air and hydrogen are supplied and exhausted to each unit cell at once. It consists of

[Problems in the Background Art] Incidentally, in the conventional fuel cell as described above, the output current is obtained by connecting a current wire (hereinafter referred to as a bus bar) 6 made of a metal plate such as a copper plate to a current extraction terminal 5 as shown in FIG. Connect with bolts 7 etc. and take out. The operating temperature of this fuel cell is usually about 200°C, but when a large number of unit cells are stacked, the stacked cells 1 and bus bars 6 expand and contract considerably due to the heat cycle that occurs when the battery starts and stops, so the current line 6 Stress is generated at the connection between the current collector plate 2 and the current extraction terminal 5, and as a result, the bolts 7 and the like of the connection become loose, resulting in poor contact.

This not only makes it impossible to obtain stable battery output, but also causes long-term low-load operation if the contact failure is large, causing the battery to exceed the maximum allowable voltage (approximately 0.8V), resulting in deterioration of battery performance. There's a problem. Furthermore, if a heat-resistant insulated cable is used instead of the busbar 6 made of a copper plate or the like, problems such as poor contact at the current extraction part caused by the stack shrinkage during the heat cycle described above can be eliminated, but on the other hand, the cost is extremely high. There are problems such as higher prices.

[Objective of the Invention] The present invention was made to solve the above-mentioned problems, and its purpose is to solve the problem between the busbar and the current extraction terminal of the current collector plate, which occurs during the heat cycle when starting and stopping battery operation. It is an object of the present invention to provide a highly reliable and inexpensive fuel cell capable of alleviating stress generated in connection parts.

[Summary of the Invention] To achieve the above object, the present invention provides a matrix for holding an electrolyte between a pair of gas diffusion electrodes having a fuel gas flow path and an oxidant gas flow path through which fuel gas and oxidant gas flow. A stacked cell is formed by stacking a plurality of unit cells, and the upper and lower sides of the stacked cell are sandwiched between current collector plates having current extraction terminals, and further stacked using clamping fittings placed above and below the stacked cell. The present invention is characterized in that a fuel cell main body is formed by tightening and fixing in a direction, a bus bar is connected to the current extraction terminal, and the bus bar itself has a spring structure.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a partial vertical sectional view showing an example of the configuration of a fuel cell according to the present invention. However, in the figure, the same parts as in FIG. 3 are designated by the same reference numerals. □ In this embodiment, in a fuel cell main body formed by sandwiching a laminated cell 1 between current collector plates 2 having current extraction terminals 5 from above and below, a part of the bus bar 6 connected to the current extraction terminal 5 is made flexible so that it can be used as a spring. A structural portion 8 is provided. In this case, the bus bar 6 is a metal plate made of copper or the like having a cross-sectional area sufficient to withstand the rated output current, and is processed to have a spring structure 8. Further, the bus bar 6 is fixed to the manifold 4 by a heat-resistant and insulating support 9 so as not to come into contact with the manifold 4, and is fixed to such an extent that it can slide even if it expands and contracts due to heat. Further, the bus bar 6 and the current extraction terminal 5 are connected with a tightening bolt 7 or the like.

Next, in the fuel cell configured as described above, the operating temperature of the fuel cell is usually around 200°C, so when a large number of unit cells are stacked, the stacked cells are 1 and the bus bar 6, the difference in expansion and contraction is absorbed by the spring structure 8, and the stress generated at the connection between the current extraction terminal 5 and the bus bar 6 can be removed.

Next, another embodiment of the present invention will be described with reference to FIGS. 2(a) and 2(b). In the figures, the same parts as in FIGS. 3 and 1 are designated by the same reference numerals, and their explanations will be omitted.

In this embodiment, as shown in FIG. 2 (a), the upper bus bar 10 is
and a lower bus bar 11, both of which are glued together with a length greater than the amount of expansion and contraction caused by heat cycles, and are tightened and fixed by a heat-resistant and insulating support 9 via a spring 12 to the extent that it can be slid. . Further, in order to facilitate the operation of the slide structure, a current terminal outlet is provided on the side surface of the current collector plate as shown in FIG. 2(b).

Next, in the fuel cell configured as described above, when a heat cycle accompanies the start and stop of operation of the fuel cell, the laminated cell 1, the upper bus bar 10, and the lower bus bar 11
Thermal expansion and contraction occurs in the upper busbar 1, but the difference in expansion and contraction is
0 and the lower bus bar 11 slide, and the stress generated at the connection between the current extraction terminal 5 and the bus bar 6 can be removed in the same manner as described above.

[Effects of the Invention] As explained above, according to the present invention, a matrix holding an electrolyte is provided between a pair of gas diffusion electrodes having a fuel gas flow path and an oxidant gas flow path through which fuel gas and oxidant gas flow. A laminated cell is formed by laminating a plurality of unit cells, and the upper and lower sides of the laminated cell are sandwiched between current collector plates having current extraction terminals, and furthermore, by means of clamping fittings placed above and below the laminated cell. The fuel cell main body is formed by tightening and fixing in the stacking direction, and the busbar is connected to the current extraction terminal, and the busbar itself has a spring structure, so that it can be tightened and fixed in the stacking direction. It is possible to provide an extremely reliable and inexpensive fuel cell that can absorb and relieve the stress generated at the connection between the bus bar and the current extraction terminal of the current collector plate due to the heat cycle.

[Brief explanation of drawings]

FIG. 1 is a partial longitudinal sectional view showing one embodiment of the present invention, FIGS. 2(a) and (b) are a partial vertical sectional view and a partial plan view showing another embodiment of the invention, and FIG. FIG. 2 is a partial longitudinal sectional view showing a conventional fuel cell. DESCRIPTION OF SYMBOLS 1... Laminated cell, 2... Current collector plate, 3... Tightening fitting, 5... Current extraction terminal, 6... Bus bar, 8...
... Spring structure part, 12... Spring. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 (a)

Claims (2)

[Claims] (1) A plurality of unit cells are stacked together, each having a matrix that holds an electrolyte between a pair of gas diffusion electrodes each having a fuel gas flow path and an oxidant gas flow path through which fuel gas and oxidant gas flow. A fuel cell body is formed by forming a stacked cell, sandwiching the top and bottom of the stacked cell with current collector plates having current extraction terminals, and then tightening and fixing the stacked cells in the stacking direction using clamping fittings placed above and below the stacked cells. A fuel cell characterized in that a current line is connected to the current extraction terminal, and the current line itself has a spring structure. (2) The product as set forth in claim (1) is characterized in that a current wire processed with a spring is arranged on a metal plate made of copper or the like having a cross-sectional area sufficient to withstand the rated output current. Fuel cell.