JPH0552630B2 - - Google Patents

Description

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

[Background of the invention]

4 to 7 show conventional examples of fuel cells. As shown in the figure, a fuel cell consists of a unit cell 4 having a fuel electrode 1 serving as a gas diffusion electrode, an oxidizer electrode 2, and an electrolyte layer 3 disposed between these electrodes 1 and 2, with a separator 5 in between. A plurality of battery bodies 6 are stacked together, and the battery body 6 is fixed to the side surface of the battery body 6 via a gasket 7, and fuel gas P is supplied to the fuel electrode 1 and the oxidizer electrode 2 as indicated by the arrows in the figure.
and a manifold 8 for supplying and discharging the oxidizing gas Q (see FIGS. 4 and 5).
The fuel electrode 1 includes an electrode substrate 1a and a catalyst layer 1b.
The oxidizer electrode 2 is composed of an electrode substrate 2a and a catalyst layer 2b, and these electrode substrates 1a,
A fuel gas P and an oxidant gas Q are respectively passed through the fuel gas P and the oxidizing gas Q (see FIG. 6).

In the fuel cell configured in this way, the electrode substrate 1
Since a and 2a are porous, the gas flow path 9 is shown using the fuel electrode 1 as an example (see FIG. 6).
As indicated by the broken line in the figure, gas leaks to the outside of the fuel electrode 1 through the substrate end (electrode end) 10 of the electrode substrate 1a, and oxidant gas Q and fuel gas P are mixed in the manifold 8. This is undesirable for operation. Therefore, a seal is required to prevent gas leakage at the electrode end portion 10 of the electrode substrate 1a. The same applies to the oxidizer electrode 2.

In addition, due to dimensional tolerances during battery manufacturing and work tolerances during battery stacking, the battery body 6 has unevenness on the surface that the gasket 7 contacts, creating a void 11 between the battery body 6 and the manifold 8. There is a risk that it will happen. As a result, gas leaked from the air 11, which not only made it impossible to control the operating pressure properly, but also posed the risk of explosion due to the mixture of hydrogen, the fuel gas, and oxygen, the oxidant gas (see Figure 7). ).

The electrode end portions 10 of the electrode substrates 1a, 2a may be sealed by impregnating the electrode end portions 10 with fluorine rubber dispersed in a dispersion liquid, or by adjusting the pore diameter of the electrode end portions 10 to the electrode end portions 10 of the electrode substrates 1a, 2a. There are wet seals that are made smaller than the above part and hold the electrolyte. However, among these, the former one in which the electrode end portion 10 was impregnated with fluorine rubber lacked airtightness because the pores in the electrode end portion 10 could not be sufficiently closed. The latter type of wet seal lacks reliability and durability because the electrolyte moves due to differential pressure and capillary action, and decreases due to evaporation. Furthermore, as a seal between the manifold 8 and the battery body 6, a grease-like sealing material was applied to the uneven portions of the surface that the gasket 7 contacts, but the electrode end portions 10 of the electrode substrates 1a and 2a mentioned above
as well as lacked reliability and durability. In addition, as related to these, for example, Japanese Patent Application Laid-Open No.
There are No. 95747 and Japanese Unexamined Patent Publication No. 152077/1983.

[Purpose of the invention]

The present invention has been made in view of the above points,
It is an object of the present invention to provide a fuel cell having a seal at the end of an electrode that is highly reliable and durable, and enables improved sealing performance between the cell main body and the manifold.

[Summary of the invention]

That is, the present invention provides notches that span the adjacent sides at the four corners of the gas diffusion electrode facing the gasket, and the notches have the same shape as the gas diffusion electrode and the same shape as the gas diffusion electrode. Elastic members having the same thickness are bonded together, and the end portion of the gas diffusion electrode parallel to the gas flow direction is covered with a U-shaped sealing material including the elastic member, and this sealing material is used as the gas diffusion electrode. The electrode and the elastic member are airtightly bonded to each other to achieve the intended purpose.

[Embodiments of the invention]

The present invention will be explained below based on the illustrated embodiments. An embodiment of the present invention is shown in FIGS. 1 to 3. 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, at the four corners of the gas diffusion electrodes 1 and 2, notches are provided in the opposing portions of the gasket 7 so as to extend over the adjacent sides, and the elastic members 12 are applied and adhered to these notches. Furthermore, two sides of the electrode end portions 10 of the gas diffusion electrodes 1 and 2 parallel to the gas flow direction were covered with a U-shaped sealing material 13. Of course, the elastic member 12 is also included.

The elastic member 12 is made of, for example, fluorine rubber. The U-shaped sealing material 13 is made of a fluorine resin material with excellent heat resistance and acid resistance, for example.
A PTFE or PFA film material or a polyimide resin film material is used. This U-shaped sealing material 13 and electrode substrates 1a, 2a
The electrode end portion 10 including the elastic member 12 is bonded to the electrode end portion 10 . To attach it, proceed as follows. A combination of PFA, which can be melted and fluidized by heating, and PTFE or polyimide film, which cannot be melted and fluidized by heating, is used in combination, and the material to be melted and fluidized is placed so as to face the electrode end 10, and the material is heat-sealed. Alternatively, PTFE film can be cured and bonded with polyimide varnish.

By doing so, gas leakage passing through the electrode ends 10 of the electrode substrates 1a and 2a shown by broken lines in FIG.
As a result, the gas seal of the electrode end 10 is not affected by differential pressure and is highly reliable and durable. Furthermore, since the portion of the electrode end portion 10 facing the gasket 7 has elasticity, among the unevenness of the laminated surface shown in FIG.
As shown in the figure, the absorption is made possible by the deformation of the elastic part.

In this way, the present invention has a structure in which the electrode ends 10 of the electrode substrates 1a and 2a are covered with a continuous film, and a sealing structure with excellent reliability and durability is obtained, and the manifold sealing surface is made of an elastic material. This makes it possible to absorb the unevenness that occurs during lamination, and in order to obtain such a good seal, the electrode plate has the same shape as before, and the lamination work can be carried out in the same way as before. In particular, no work is required for sealing.

Note that in the above embodiments, the electrode substrates 1a, 2
The shape of the notch provided at a is not limited to the L-shape as shown in the figure, but may be any shape such as a square or a rectangle.

〔Effect of the invention〕

As explained above, the present invention provides a notch that spans the adjacent side at the four corners of the gas diffusion electrode that faces the gasket, and a notch that has the same shape as the notch and An elastic member having the same thickness as the gas diffusion electrode is adhered, and the end portion of the gas diffusion electrode parallel to the gas flow direction is covered with a U-shaped sealing material including the elastic member, and this sealing material is Since the gas diffusion electrode and the elastic member are airtightly adhered to each other, gas that attempts to leak through the substrate of the gas diffusion electrode is sufficiently prevented by the U-shaped sealing material, and the manifold Gas leakage from the seams is prevented because the elastic members fitted and bonded to the notches at the four corners of the electrodes absorb the unevenness that occurs when the electrodes are laminated, and the two are brought into close contact with each other in a sufficient amount of time. Gas leakage between the edges, that is, leakage due to interfacial cracks where the elastic member is bonded to the electrode, can be avoided because a U-shaped sealing material is applied to the end of the electrode, including the elastic member. The electrode plates are sealed with a U-shaped sealing material, and the elastic members are aligned with the four corner notches of the electrode and paired with the U-shaped sealing material, so the electrode plate stacking work can be done in the same way as before. be able to.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of the electrode substrate plane of an embodiment of the fuel cell of the present invention, FIG. 2 is a front view of the electrode substrate of the embodiment, and FIG. 3 is a portion of the stacked battery of the embodiment. 4 is a perspective view of a conventional fuel cell, FIG. 5 is a partial sectional view of a conventional fuel cell,
FIG. 6 is a longitudinal sectional side view of the electrode end of a conventional fuel cell, and FIG. 7 is a side view of the conventional fuel cell. 1... Fuel electrode (gas diffusion electrode), 1a... electrode substrate, 2... Oxidizer electrode (gas diffusion electrode), 2a...
...electrode substrate, 3...electrolyte layer, 4...unit battery,
5... Separator, 6... Battery body, 7... Gasket, 8... Manifold, 9... Gas flow path,
10... Electrode end (end of electrode substrate), 11...
Empty, 12, 12a...Elastic member, 13...U-shaped sealing material, 14...Adhesive layer.

Claims (1)

[Scope of Claims] 1. A battery comprising 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, The fuel cell has a pair of gas diffusion electrodes having a gas flow path, and a matrix disposed between these gas diffusion electrodes and holding an electrolyte, and the cell main body and the manifold are sealed via a gasket. In this step, cutouts are provided in the four corners of the gas diffusion electrode facing the gasket, and the cutouts extend over adjacent sides.
An elastic member having the same shape as the notch and the same thickness as the gas diffusion electrode is adhered to the notch,
and covering an end portion of the gas diffusion electrode parallel to the gas flow direction, including the elastic member, with a U-shaped sealing material, and adhering this sealing material to the gas diffusion electrode and the elastic member in an airtight manner. A fuel cell characterized by: