JPS61216251A - Fuel cell - Google Patents

Abstract

PURPOSE:To prevent leak of gas between the fuel electrode and air electrode by forming a gas sealing with a gas untransmitting material filling the recessed stripes arranged to the end portion of a gas diffusion electrode and the end portion of the electrode opposing the bottom side of such recessed stripes and flexible thin film provided between the separator and end portion of the electrode. CONSTITUTION:By providing a recessed stripe 12 to the end portion of the fuel electrode 1A and the air electrode 1B, the thin area opposing to the bottom side of recessed stripe part 12 is well filled with untransmitting material 11, while the recessed stripe portion 12 is filled with gas untransmitting material 13 and a cell body is tightened with a filling pressure. Therefore, leak of gas in the right angle to the gas flow path 9 of the fuel electrode 1A, the air electrode 1B is prevented. Since a flexible thin film 10 is provided being tightened with adequate pressure between the separators 5A, 5B, the flexible thin film 10 works as a gasket preventing leak of gas. Thereby, gas leak between the fuel electrode 1A and the air electrode 1B can be prevented.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to fuel cells.

[Background of the invention]

5 and 6 show conventional examples of fuel cells. As shown in the figure, the fuel cell has a fuel electrode IA, which is a gas diffusion electrode, an air electrode IB, and a unit cell 4 having a separator 5A.

It is composed of a plurality of battery bodies 6 stacked together via 5B, and a manifold 7 that is firmly attached to the side surface of the battery body 6 and supplies and discharges gas to and from the battery body 6. In the figure, numeral 8 denotes a spacer placed at the ends of the electrolyte layer 3 and the catalyst layer 2.

In the fuel cell configured as described above, the fuel electrode IA and the air electrode IB function as gas diffusion electrodes, so a porous substrate using carbon fiber is used. Therefore, the gas flowing through the gas flow path 9 provided in the fuel electrode IA and the air electrode IB flows from the fuel electrode IA to the air electrode IB as shown by arrows in the figure.
, gas flows to the outside through the pores of the air electrode IB and the interface with the separators 5A and 5B, or gas flows in from the outside, causing a gas short circuit, and direct reaction stimulation between the gas, that is, the fuel gas and the oxidant gas. There is a risk of it happening.

This reaction reduces the efficiency of the fuel cell and poses a risk of explosion, so an appropriate sealing structure is required.

As a gas seal, the end of the electrode is covered with a flexible thin film 10 as shown in FIG.
(see Publication No. 2), or as shown in FIG. 8, the end of the electrode was filled with a slurry-like filler 11. However, the work involved in filling the former electrode end with the flexible thin film 10t-aL5 is complicated, and the latter filling the pores of the fuel electrode IA and air electrode IB with the filler 11 is not sufficient. Since it is difficult to use, there is a drawback that the seal may be incomplete.

[Purpose of the invention]

The present invention has been made in view of the above points, and it is an object of the present invention to provide a fuel cell that can prevent gas short circuit between the fuel electrode and the thrust electrode.

[Summary of the invention]

In other words, the present invention comprises a battery body in which a plurality of unit batteries are stacked with separators interposed therebetween, and a manifold disposed on a side surface of the battery body for supplying and discharging gas to and from the battery body. has a pair of gas diffusion electrodes that are arranged opposite to each other and have a gas flow path, nine electrolyte layers are provided between these gas diffusion electrodes, and the gas diffusion electrode has a structure that prevents the gas from leaking from the end thereof. In a fuel cell provided with a gas seal that prevents
A groove parallel to the gas flow path is provided at the end of the gas diffusion electrode, and a gas impermeable material is filled in the groove and at the end of the electrode opposite to the bottom side of the groove. ,
The gas seal is characterized by comprising a flexible thin film inserted between the separator and the end of the electrode, whereby the gas seal creates a gas flow path at the end of the gas diffusion electrode. a gas-impermeable material filled in the groove provided parallel to the groove and the end of the electrode opposite to the bottom side of the groove; and a flexible thin film inserted between the separator and the electrode end. It will be composed of

[Embodiments of the invention]

The present invention will be explained below based on the illustrated embodiments. FIG. 1 shows an embodiment of the invention. Note that parts that are the same as those in the conventional system are given the same reference numerals, and therefore their explanations will be omitted. In this embodiment, gas seals are provided at the ends of the fuel electrode IA and the air electrode IB in parallel with the gas flow path 9, and inside the groove 12 and on the bottom side of the groove 12. It is composed of an impermeable material 13.11 filled in the opposing electrode ends, and a flexible thin film 10 inserted between the separators 5A, 5B and the electrode ends. By doing so, the casseal is placed in the groove 12 provided in parallel with the gas flow path 9 at the ends of the fuel electrode IA and the air electrode IB, and in the electrode end opposite to the bottom side of the groove 12. Impermeable material 13 filled respectively
．． 11, and a flexible thin film 10 inserted between the separators 5A, 5B and the electrode ends, thereby making it possible to prevent gas short circuit between the fuel electrode IA and the air electrode 18. can be obtained.

That is, in the unit cells constituting the fuel cell, the ends of the fuel electrode IA and the air electrode IB are formed into grooves, and separators 5A, 5 are formed.
A flexible thin film 10 is sandwiched between the flexible thin film 10 and B. Fuel electrode I
A. By forming the end of the air electrode IB into a groove by providing the groove 12, the remaining thin portion facing the bottom side of the groove 12 is made of a thin gas-impermeable material. 11
In other words, the slurry-like filler is easily filled, the gas-impermeable material 11 is well filled, the grooves 12 are filled with the waste-impermeable material 13, and the battery body is filled with 1 crn2.
It can be tightened with a pressure of several kg to 10 yu per unit. Therefore, the leakage of waste flowing through the gas flow paths 9 of the fuel electrode IA and the air electrode IB in the direction perpendicular to the gas flow path 9 is prevented by the waste impermeable material 13 filled in the groove 12 and the groove. In addition to being blocked by the gas-impermeable material 11 filled in the portions filled with gas, a flexible thin FV&IO is interposed between the separators 5A and 5B and tightened with an appropriate pressure. The thin film 10 acts as a gasket and prevents leakage of waste. In this way, it is possible not only to prevent the gas flowing through the gas flow path 9 from flowing out to the outside through the pores of the fuel electrode IA and air electrode IB and the interface with the separators 5A and 5B, but also to prevent gas from flowing from the outside. can be prevented from flowing in, and a gas short circuit between the fuel electrode IA and the air electrode 18 can be prevented.

According to experiments, a carbon resin dispersion or a polyimide resin solution is suitable as the gas-impermeable material 11 to be filled in the remaining part of the electrode plate formed by the four-striped portion 12, that is, the electrode end opposite to the bottom side of the grooved striped portion 12. A mixture of a fluororesin dispersion and graphite powder with a particle size of 20 μm or less is suitable as the gas-impermeable material 13 to be filled in the grooved portion 12, but the mixture is not limited to graphite powder. , fluororesin powder, silicone carbide powder, etc. can also be used. In addition, when the gas impermeable material 11.13 is a fluororesin, this 127
Heating above 0C strengthens the water repellency of the gas-impermeable material, which prevents the electrolyte that has flowed into the fuel electrode IA% air electrode IB from flowing out, resulting in a liquid seal. An effective seal is obtained in conjunction with a seal of gas-impermeable material.

The dimensions of the grooved portion 12 are as follows: The thickness of the remaining portion of the grooved portion 12
When the thickness of the electrode end facing the bottom side of the electrode plate (the thickness of the electrode end facing the bottom side) is reduced from 1/3 to 115% of the thickness of the original electrode plate (electrode end), the filling ratio of the gas-impermeable material 11 becomes the original value. The thickness has been improved from 50 to 80 inches compared to when the thickness was
It can be reduced to 10.

Fuel electrode IA, air electrode IB and separator 5A.

5B, the flexible thin film 10 has a thickness of 100 mm.
A fluororesin film or polyimide film with a size of less than μ is suitable, and it can be used by bonding with adhesive or by heat sealing in the case of fluororesin film.
In this case, these flexible thin films 10 and the fuel electrode 1'A
Since the % air electrode IB is integrated, there is an advantage that the unit battery can be easily assembled. In this way, the pores at the tm ends are reduced, and in addition to being able to be sufficiently filled with the gas-impermeable material 11.13, a seal can be formed between the separators 5A, 5B and the electrode ends, and flexible It is not necessary to cover the entire end of the electrode with the thin film 10, which simplifies the work.

Another embodiment of the invention is shown in FIG.

In this example, the flexible thin film 10 was placed in close contact with the grooved portion 12 at the end of the electrode. By doing this, the concave portion 1
A flexible thin film 10 is tightly attached to the grooves 12, and a liquid such as an electrolytic solution can be filled into the grooves 12, so that a liquid seal can also be formed between the separators 5A, 5B and the electrode ends. This makes it possible to improve the sealing effect in this part compared to the case described above.

FIG. 3 shows yet another embodiment of the invention. In this embodiment, a plurality of grooves 12 are provided in parallel. By doing so, the gas-impermeable material 11 occupies the electrode end.
．． Since the amount of 13 is larger than in the case described above, the sealing effect at the end of the electrode can be improved more than in the case described above.

FIG. 4 shows yet another embodiment of the invention. In this embodiment, the grooved portions 12 were provided alternately at the ends of the fuel electrode IA and the air electrode IB with the catalyst layer 2 side. That is, the electrodes were arranged so that the bottom side and the opening side of the concave strip 12 were alternately located at the end of the electrode. By doing so, the concave portions 12 with alternating bottom sides and opening sides are provided in parallel with each other, and the same effect as in the case described above can be achieved.

Note that in this case, as in the case of P described above, it is necessary to increase the thickness of the groove remaining at the end of the electrode, and a sufficient sealing layer cannot be obtained by filling the groove remaining with only the - groove groove 12. It is effective in some cases.

〔Effect of the invention〕

As described above, the present invention prevents gas short circuit between the fuel electrode and the air electrode, thereby making it possible to obtain a fuel cell that can prevent gas short circuit between the fuel electrode and the air electrode.

[Brief explanation of the drawing]

1 to 4 are longitudinal sectional side views of electrode ends showing different embodiments of the fuel cell of the present invention, FIG. 5 is a perspective view of a conventional fuel cell, and FIG. 6 is a conventional fuel cell electrode end view. 7 and 8 are vertical side views showing gas seals at different electrode ends of a conventional fuel cell. IA...fuel electrode, (cass diffusion electrode), IB... air electrode (cass diffusion electrode), 2...catalyst layer, 3...electrolyte layer, 4...unit cell, 5A, 5B.・Separator,
6... Battery body, 7... Manifold, 8... Spacer, 9... Gas flow path, 10... Flexible thin film, 1
DESCRIPTION OF SYMBOLS 1... Gas-impermeable material, 12... Concave portion, 13.
...Gas impermeable material.

Claims (1)

[Claims] 1. A battery body comprising a plurality of unit batteries stacked together with separators interposed therebetween, and a manifold disposed on a side surface of the battery body for supplying and discharging gas to and from the battery body; The battery includes a pair of gas diffusion electrodes that are arranged opposite each other and have a gas flow path, and an electrolyte layer provided between these gas diffusion electrodes, and the gas can leak from the ends of the gas diffusion electrodes. In the fuel cell, the gas seal is provided with a groove parallel to the gas flow path at the end of the gas diffusion electrode, and the gas seal is provided with a groove parallel to the gas flow path, and It is characterized by being composed of a gas-impermeable material filled in each of the electrode ends facing the bottom side, and a flexible thin film inserted between the separator and the electrode end. Fuel cell. 2. The gas-impermeable material filled in the groove is a mixture of a fluorine resin dispersion liquid or a polyimide resin solution and any one of graphite powder, fluorine resin powder, and silicone carbide powder. A fuel cell according to claim 1. 3. The method according to claim 1, wherein the gas-impermeable material filled in the end portion of the electrode facing the bottom side of the grooved portion is a fluorine-based resin dispersion or a polyimide-based resin solution. Fuel cell. 4. The fuel cell according to claim 1, wherein the flexible thin film is one of a fluorine resin film and a polyimide resin film.