JPS6237507B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fuel cells, and more particularly to a fuel cell stack consisting of a plurality of fuel cells electrically connected in series.

Figure 1 shows the structure of a fuel cell 1 of a conventionally used hydrogen-oxygen fuel cell stack.
2 is an air electrode, 3 is a fuel electrode, and 4 is an electrolyte layer inserted in a compartment formed between both electrodes 2 and 3, and each electrode includes a catalyst layer on its electrolyte side. An air passage 5 is provided on the non-electrolyte side of the air electrode 2 to form a reaction gas space for passing air, and an air passage 5 is provided on the non-electrolyte side of the fuel electrode 3 to form a reaction gas space for passing fuel. The air passage 5 and the fuel gas passage 6 are provided on both sides of the separator plate 7.

In the fuel cell power generation equipment, a plurality of fuel cells 1 are stacked with separators 7 in between and electrically connected in series to form a fuel cell stack.

In such a fuel cell stack, the electrolytic solution gradually evaporates during operation of the fuel cell, and therefore decreases unless replenished. When the electrolyte runs out, ions cannot flow between the electrodes and no power is generated, so it is necessary to replenish the electrolyte. For this reason, in the conventional fuel cell stack, a common electrolyte chamber 8 is provided passing through the stacked fuel cells 1 . Therefore, all separators 7, electric poles 2,
Holes 81, 82, 83, 84 for common electrolyte chambers and a seal structure for preventing electrolyte leakage along the laminated surface are required in the electrolyte layer 4 and fuel electrode 3, and the number of parts such as packing increases. This required a lot of machining, such as packing grooves, and the structure was complicated, making it difficult to assemble.

Furthermore, in this conventional fuel cell stack,
Since the common electrolyte chamber 8 is in direct contact with the separator plate 7 of each electric ground, each stacked fuel cell 1 is short-circuited by the electrolyte, and a leakage current is generated through the electrolyte. The drawback was that the power generation efficiency was reduced accordingly.

An object of the present invention is to provide a fuel cell stack that eliminates such drawbacks and has a simple and easy-to-assemble structure. In a fuel cell stack consisting of a stacked body in which a plurality of fuel cells each having an electrolytic solution layer are stacked via a separator plate provided with a gas flow path, the stacked body includes a layer parallel to the surface of the fuel cell. an electrolyte supply channel provided in the manifold, which is provided in the manifold and is inserted into the outer surface of the stack, and which communicates with the electrolyte layer and has an opening in the side surface of the stack; The electrolyte supply path of each of the cells has a common electrolyte chamber communicating through the opening.

Examples will be described below.

FIG. 2 is a cross-sectional view of a hydrogen-oxygen fuel cell stack according to an embodiment, FIG. 3 is a detailed cross-sectional view of the main part of FIG. 2, and FIG. 4 is a line A-A in FIG. 2. FIG. 5 is a vertical cross-sectional view of the main part taken along the line B-B in FIG. The old part is shown enlarged.
Figure 6 is a cross-sectional view of the main part taken along line C-C in Figure 2, showing the positional relationship when the fuel cell stack is viewed from the side. is shown. In these figures, the same parts as in FIG. 1 are given the same reference numerals.

This fuel cell stack, as shown in FIG.
The fuel cell 1 is constructed by stacking a plurality of fuel gas passages 6, fuel electrodes 3, electrolyte layer 4, air electrodes 2, air passages 5, and separators 7, and each separator 7 is connected to its end. By providing a packing 11 at the end of the fuel electrode 3 and another packing 12 overlapping a part of the end of the fuel electrode 3 and overlapping the packing 11, the air electrode 2, the electrolyte layer 4, the fuel electrode 3,
An electrolyte supply channel 13a (an electrolyte supply channel provided on the same plane as the air passage 5 on the separator 7, and an electrolyte supply passage provided on the same plane as the fuel passage 6 on the separator 7) is provided between the packing 11, the packing 12 and the separator 7. In the electrolyte supply channels and structures related to these electrolyte supply channels, parts where it is necessary to distinguish between the two are marked with a and b, respectively), and such structures By doing so, the electrolyte supply path 13a communicates with the electrolyte layer 4. Here, one example of the constituent materials of this fuel cell 1 will be given. The air electrode 2 and the fuel electrode 3 are made of porous carbon paper using a platinum-based catalyst, and the electrolyte layer 4 is made of phenol cloth or inorganic fibers impregnated with an electrolyte mainly containing phosphoric acid. The separator 7 is made of dense graphite, and the packings 11 and 12 are made of fluorocarbon rubber. In addition, electrolyte supply path 1
Reference numeral 4 denotes a groove for widening the cross section of the electrolyte supply path 13 provided near the end of the separator 7, and this groove may not be provided depending on the case. This electrolyte supply path 13 is connected to the end side surface of the fuel cell stack, and forms an opening 15 in the side surface of the fuel cell stack.

FIG. 2 shows the relationship between the fuel cell stack and the air manifold 9, fuel gas manifold 10, and electrolyte manifold 17.
Electrolyte manifolds 17a and 17b each having a common electrolyte chamber 16a and 16b are disposed facing each opening 15, and these electrolyte manifolds 17a and 17b are similar to air manifolds 9 and 17b, respectively. 9 and the fuel gas manifolds 10, 10. Note that the electrolyte manifold may be placed outside the air or fuel gas manifold.

In this fuel cell stack, the electrolyte is introduced from the outside via an electrolyte supply port 18 or 19 into a common electrolyte chamber 16 provided in an electrolyte manifold 17, and then The electrolyte is supplied to the electrolyte supply path 13 of each fuel cell 1 from the opening 15 via the electrolyte 20 . Note that 21 is a gas inlet, and 22 and 23 are packings.

With this structure, there is no need for an electrolyte sealing structure for each separator as in the prior art, and a common electrolyte chamber can be installed all at once after stacking the fuel cells, resulting in a simpler structure. It is simple and easy to assemble.

In addition, since the common electrolyte chamber is provided outside the battery stack, it is possible to increase the length of the electrolyte short-circuit path that short-circuits each fuel cell via the common electrolyte chamber, or to disconnect the short-circuit path. By reducing the area, short circuit resistance can be increased and leakage current can be reduced.

FIG. 7 shows a cross section of a main part of another embodiment, and the difference between this embodiment and the previous embodiment is that one of the communication ports 20 between the electrolyte supply path 13 and the common electrolyte chamber 16 is A weir 24 is provided in the section, and the height of this weir 24 is higher than the upper surface of the electrolyte supply channel 13 of the corresponding fuel cell. In the fuel cell stack constructed in this way,
After the common electrolyte chamber 16 is filled with electrolyte and the electrolyte is supplied to the electrolyte supply path 13, the electrolyte in the common electrolyte chamber 16 is discharged, and the fuel cell is operated. By doing this, during operation of the fuel cell, there is no electrolyte passage that short-circuits each fuel cell, and since the weir is provided, the electrolyte can be retained in the electrolyte supply path. I can do it.

In other words, the fuel cell stack of this embodiment not only simplifies the structure and facilitates assembly as in the previous embodiment, but also improves electrolysis between the stacked fuel cells. Leakage current through the liquid can be reduced.

As described above, the fuel cell stack of the present invention makes it possible to provide a fuel cell stack with a simple and easy-to-assemble structure, and has great industrial effects.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view for explaining the structure of a conventional fuel cell, FIG. 2 is a cross-sectional view of an embodiment of the fuel cell stack of the present invention, and FIG. Detailed cross-sectional view of the main part, Figure 4 is also the same as Figure 2.
Figure 5 is a vertical cross-sectional view of the main part taken along line A-A in Figure 2, Figure 6 is a cross-sectional view of the main part taken along line B-B in Figure 2, and Figure 6 is a cross-sectional view of the main part taken along line C-C in Figure 2. Arrow view, 7th
The figure is a longitudinal sectional view of the main part at the same position as FIG. 5 of another embodiment. DESCRIPTION OF SYMBOLS 1... Fuel cell, 2... Air electrode, 3... Fuel electrode, 4... Electrolyte layer, 5... Air passage, 6...
Fuel gas passage, 7... Separation plate, 11, 12... Packing, 13, 14... Electrolyte supply path, 15...
...opening, 16...common electrolyte chamber, 17...electrolyte manifold, 18, 19...electrolyte supply port, 20...communication port, 24...weir.

Claims (1)

[Claims] 1. A fuel cell having a first electrode, a second electrode, and an electrolyte layer interposed between the two electrodes,
In a fuel cell stack consisting of a plurality of stacked bodies stacked together with a separator plate provided with a gas flow path, a fuel cell stack is provided in the stacked body parallel to the surface of the fuel cell and communicates with the electrolyte layer. , and an electrolyte supply path having an opening in a side surface of the laminate;
A common electrolyte chamber is provided in a manifold inserted into the outer surface of the laminate, and the electrolyte supply path of each of the fuel cells communicates through the opening. A fuel cell stack featuring: 2. The fuel cell stack according to claim 1, wherein the separator has a groove forming a part of the electrolyte supply path provided in parallel to the gas flow path provided in the separator. . 3. The fuel cell stack according to claim 1, wherein a weir is provided between the electrolyte supply path and the common electrolyte chamber, the weir having an upper surface higher than the upper surface of the electrolyte supply path.