JPS628456A - Fuel cell - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

[Background of the abolition of the Ming Dynasty]

FIG. 3 shows a conventional example of a fuel cell.

As shown in the figure, in a fuel cell, a unit cell 4 has a porous fuel electrode 1, which is a pair of gas diffusion electrodes, an oxidizer electrode 2, and an electrolyte layer 3 sandwiched between them. A plurality of them are stacked with 5 interposed therebetween. As shown in FIG. 4, each of the fuel electrode 1 and the oxidizer electrode 2 has a gas flow path 6 on one surface that forms a flow path for the fuel gas and oxidizer gas, and the other surface is flat. Grooved porous substrates 1a, '2a formed in , and this porous substrate 1a.

Catalyst layer lb, 2 formed by coating etc. on the flat surface of 2a.
Also, the six gas flow paths for fuel gas and oxidant gas formed from the six gas flow paths formed from the six gas flow paths b are stacked so that their directions intersect with each other. Therefore, in order to prevent the fuel gas flowing through one gas flow path and the oxidizing gas flowing through the gas flow path 6 above or below from mixing with each other, the electrode end 7 parallel to each gas flow path 6 is sealed with gas. It is necessary to.

In this case, the gas leakage path to be sealed is the one that leaks from the gas flow path 6 through the entire electrode end 7 to the outside as shown by the arrow in FIG. There is a path B that leaks to the outside from the contact interface between the electrode end 7 and the airtight plate 5.

The gas seal for the electrode end 7 has conventionally been achieved by making the pore diameter of the electrode end 7 smaller than that of other parts of the electrode substrates 1a and 2a, as described in, for example, Japanese Unexamined Patent Publication No. 58-166668. Electrolyte? Some proposals have been made, such as one in which the electrode end 7 is impregnated with a sealing material or coated with a sealing material, as disclosed in Japanese Patent Application Laid-open No. 59-68171. However, in the former case, is it due to fluctuations in differential pressure? Due to the 8 movement and decrease of lj solution, stable gas sealing cannot be achieved from 4n, and in the latter case, it is difficult to form a uniform and stable sealing material film due to the occurrence of pinholes, and a large amount of sealing processing is required. This method has disadvantages such as requiring a lot of man-hours.

[Purpose of the invention]

The present invention has been made in view of the above points, and an object of the present invention is to provide a fuel cell that makes it possible to improve the reliability and durability of the gas seal at the end of the electrode. be.

[Summary of the invention]

That is, in the present invention, a plurality of unit cells each having a pair of gas diffusion electrodes and an electrolytic i-layer disposed between them are placed in a box 1 through an airtight plate. ! In addition, each of the gas diffusion electrodes is provided with a gas flow path through which gas flows, and a gas seal is provided at an end of the electrode parallel to the gas flow path to prevent the gas from leaking. In a fuel cell, the gas seal is formed of a membrane formed by partially depositing a porous mat of fluororesin ##I fibers, and the porous mats located on both sides of this membrane and impregnated with an electrolyte. This product is characterized by a gas seal formed of a coating material made of It is made of a covering material consisting of a porous mat impregnated with an electrolytic solution.

[Embodiments of the invention]

The present invention will be explained below based on the illustrated embodiments. An embodiment of the invention is shown in FIGS. 1 and 2. FIG. 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, the gas seal is made of a membrane 8b formed by fusion-bonding a part of porous pine) 8a made of fluororesin fibers, and porous mats 8a located on both sides of this membrane 8b and impregnated with an electrolytic solution. The coating material 8 was made of By doing this, the gas seal consists of a membrane 8b formed by fusion-bonding a part of the porous pine () 8a made of fluororesin fibers, and the membrane 8b.
porous pine located on both sides of b and impregnated with electrolyte)
8a, it is possible to obtain a fuel cell that improves the reliability and durability of the gas seal at the electrode end 7.

That is, the electrode end 7 parallel to the gas flow path 6 of the oxidizer electrode 2
is covered with a covering material 8, the part facing the end face 9 of the electrode end is covered with fluororesin l [8b, and the part facing the upper and lower surfaces of the electrode end 7 is covered with a porous mat 8a of fluororesin fiber. I did it like that. This membrane 8b and the porous mat 8a are formed integrally, and the porous mat 8a is made of ! Impregnated with electrolyte.

By doing this, the porous pine (8a) impregnated with electrolyte and placed on the upper and lower surfaces of the electrode end 7 is sandwiched between the airtight plate 5 and the oxidizer electrode 2 on one side. , the other surface is sandwiched between the oxidizer electrode 2 and the fuel electrode 1 together with the electrolyte layer 3. As mentioned above, the covering material 8 consists of a continuous film 8b of an appropriate width made by heating and pressing the center of the porous fluororesin fiber 8a in the width direction and fusing the fibers, and a porous film on both sides of this film 8b. The covering material 8 having such a shape is made of tetrafluoroethylene/perfluoroalkyl which has a low melting temperature among fluororesins, which are thermoplastic resins, and can form the pattern 8b by pressure heating. This can be easily achieved by using a nonwoven fabric of fibers such as vinyl ether copolymer or tetrafluoroethylene/hexafluoropropylene copolymer and heating under pressure with a roll heater or the like.

Moreover, this porous mat 8a made of fluororesin fibers with strong water repellency can be changed into a hydrophilic mat by immersing it in alcohol and then volatilizing the alcohol content.

As described above, according to this embodiment, leakage of gas from the gas flow path 6 through the electrode end 7 is sealed by the continuous membrane 8b, and an excellent gas sealing effect can be obtained without being affected by differential pressure. Furthermore, leakage of gas from the contact interface between the electrode end 7 and the airtight plate 5 is sealed by a liquid seal formed by the electrolytic solution impregnated into the porous mat 8a. Moreover, by using the highly elastic porous mat 8a at the contact interface, the sealing performance can be further improved by tightening after lamination without being affected by the surface condition of the interface.

In other words, 'it! 4'N end end surface 9 is a continuous film 8b
At the same time, the contact interface between the electrode end 7 and the airtight plate 5 is sealed with a liquid seal formed by an electrolytic solution impregnated into a highly elastic porous mat 8a of fluororesin fiber. This results in a gas seal that is more reliable and durable than conventional gas seals. And the materials used are acid resistant.

Since it is a fluororesin with excellent heat resistance, once it is formed into a structure, its properties do not change and it has excellent durability.

In this embodiment, a case has been described in which the end portion 7 of the oxidizer electrode 2 parallel to the gas flow path 6 is covered with the covering material 8; Needless to say, the covering material 8 is also provided on the surface.

[Inventions and effects]

As described above, the present invention improves the reliability and durability of the gas seal at the electrode end, making it possible to improve the reliability and durability of the gas seal at the electrode end. You can get free batteries.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional side view of the electrode end of an embodiment of the fuel cell of the present invention, Fig. 2 is a perspective view of the covering material of the same embodiment, and Fig. 3 is a perspective view of a conventional fuel cell, fJ4. The figure is a vertical side view of a unit cell of a conventional fuel cell, and FIG. 5 is a vertical side view of an electrode end of a conventional fuel cell. DESCRIPTION OF SYMBOLS 1... Fuel electrode (gas diffusion electrode), 1a... Grooved porous substrate, 1b... Catalyst layer, 2... Oxidizer electrode (C gas diffusion electrode), 2a... Grooved porous Board, 2b...
Catalyst layer, 3... Electrolyte layer, 4... Unit battery, 5...
・Airtight plate, 6... Gas flow path, 7... Electrode end, end ・
・Covering material, 8a...Multiple 1r￥J Iris 2 Figure and θ Sweat

Claims (1)

[Claims] 1. A plurality of unit batteries each having a pair of gas diffusion electrodes and an electrolyte layer disposed between them are stacked with an airtight plate interposed therebetween, and a gas flows through each of the gas diffusion electrodes. In a fuel cell, a gas flow path is provided, and a gas seal is provided at an end of an electrode parallel to the gas flow path to prevent the gas from leaking.
A fuel characterized by being formed of a covering material consisting of a membrane formed by fusing a part of a porous mat of fluororesin fibers, and the porous mats located on both sides of the membrane and impregnated with an electrolyte. battery. 2. A patent in which the coating material is attached to the electrode end such that the membrane covers the side surface of the electrode end, and the porous mat covers the upper and lower surfaces of the electrode end. A fuel cell according to claim 1. 3. The fuel cell according to claim 1 or 2, wherein the coating material is formed by integrally forming the membrane and the porous mat. 4. The fluororesin fiber is made of tetrafluoroethylene.
The fuel cell according to claim 1, which is formed of a perfluoroalkyl vinyl ether copolymer or a tetrafluoroethylene/hexafluoropropylene copolymer.