JPS62103978A - Fuel cell - Google Patents

Abstract

PURPOSE:To improve the reliability and sealing property of a fuel cell, by interposing a thermoplastic sealant between a pouch seal and a separator and another thermoplastic sealant between the pouch seal and a spacer, and using the operation temperature of the fuel cell to molten the sealants to fill very small boundary gaps with the molten sealants to perform sealing. CONSTITUTION:A sealant is interposed between a separator 5 and a pouch seal 11 surrounding the end 9 of an electrode. Another sealant 12 is interposed between the pouch seal 11 and a spacer. Each sealant 12 is a thin tape of about 1-10mum in thickness at the time of assembly of a fuel cell and is made of a fluorine resin such as a vinyliden fluoride resin, which is molten at the fuel cell operation temperature of 180-220 deg.C. Very small gaps made doe to the projections, recesses and curves of the surfaces of the pouch seal and the separator are filled with the molten sealants to seal up the boundary between the pouch seal and the spacer and that between the pouch seal and the separator. The sealing property of the fuel cell and the reliability of gas sealing thereof are thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fuel cell, and particularly to a unit cell end seal suitable for gas nol and its purchase.

[Background of the invention]

As shown in FIG. 5, a fuel cell consists of a unit cell 4 having a porous fuel electrode 1, which is a pair of gas diffusion electrodes, an oxidizer electrode 2, and an electrolyte layer 3 disposed between these electrodes, and a separator. A plurality of battery bodies 6 are laminated with cells 5 interposed therebetween, and fuel P1 and oxidizer Q gas are fixed to the sides of the battery body 6 and are attached to the fuel electrode 1 and the oxidizer electrode 2 as indicated by arrows in the figure. and a device 17 for supplying and discharging the water, respectively.

As shown in FIG. 6, the fuel electrode 1 and the oxidizer electrode 2 have electrode substrates 1a and 2a and a catalyst layer 1b, respectively.

2b, and fuel P is formed on the electrode substrates 1a and 2a, respectively.
Gas channels 8 through which the oxidizing agent Q flows are provided respectively. Furthermore, a spacer 10 is inserted between the electrodes 1.2.

In the fuel cell configured in this way, the electrode substrates la, 2a
Since the fuel electrode l is porous, as shown in FIG. 6 using the fuel electrode as an example, leakage occurs from the gas flow path 8 through the electrode end 9 to the outside of the fuel electrode l (indicated by a broken line in the figure). is necessary. Since leakage to the outside of the fuel electrode 1 still occurs through the interface between the electrode end 9 and the separator 5 and the interface between the electrode end 9 and the spacer 10 (indicated by a solid line in the figure), sealing is required.

Conventionally, as a sealing method used for this electrode end, a method is known in which a film made of resin is bonded under heat and pressure to the end of the electrode to surround the electrode end, as shown in, for example, Japanese Unexamined Patent Publication No. 59-132572. (See Figures 7 and 8)
. However, although this method can prevent leakage through the electrode end 9, it is difficult to prevent leakage from the interface between the bag seal 11 and the separator 5 or the interface between the bag seal 11 and the spacer 10.

[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 equipped with a unit cell end gas seal structure having good reliability and sealing performance.

[Summary of the invention]

That is, in the present invention, gas leakage from the electrode end can be prevented by surrounding the electrode end with a conventional heat-pressed film, but gas leakage between the bag seal and the spacer and between the bag seal and the spacer is In order to compensate for the insufficient surface sealing, a thermoplastic sealing material was inserted between the bag seal and the separator and between the bag seal and the spacer, and it melted at the fuel cell operating temperature and became liquid, filling the small gap at the interface with liquid. By performing the filling and sealing, a seal structure with improved sealing performance and reliability can be obtained.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. In this embodiment, a sealing material 12 is inserted between the bag seal 11 surrounding the electrode end 9 and the separator 5, and also between the bag seal 11 and the spacer. The sealing material 12 should be in the form of a thin film tape (approximately 1 to 10 μm) when assembling the battery, and the battery operating temperature should be 180C or higher.
A fluororesin that melts and becomes liquid at 220C is used, such as vinylidene fluoride resin (VdF).

According to this embodiment, the minute gaps caused by the unevenness and bending of the surfaces of the bag seal and separator are filled with the melted liquid sealing material to eliminate the minute gaps and between the bag seal and the separator and between the bag seal and the bag seal. The sealing at the interface between the spacers becomes complete, improving the sealing performance and improving the reliability of the gas seal.

Next, FIGS. 2 and 3 show other embodiments of the present invention. In FIG. 2, a groove is provided in the separator 5 to accommodate the sealing material 12, and the molten sealing material 12 is prevented from moving to other places to ensure the interface seal between the bag seal and the separator. The same effects as in the previous embodiment can be obtained. FIG. 3 also shows the separator 5 and the electrode end 9.
A groove is provided in the groove, and the sealant 12 is stored in the groove and used as a guide during assembly to facilitate the assembly work, and the liquid sealant 12 is stored in the groove to produce the same effect as shown in FIG. This is what I wanted to get.

Further, FIG. 4 shows another embodiment of the present invention. Electrode end 9
The parts are made finer and the same effect as in Fig. 3 is obtained.

〔Effect of the invention〕

According to the present invention, it is possible to prevent gas leakage from the interfaces between the bag seal and the separator and between the bag seal and the spacer, thereby improving gas sealing properties at the ends of the cell and improving reliability against gas leaks. It has the effect of

[Brief explanation of drawings]

FIGS. 1 to 4 are cross-sectional views showing embodiments of the present invention, FIG. 5 is a perspective view showing the structure of a conventional fuel cell, and FIG. 6 is a cross-sectional view of the electrode end of a single cell of a conventional fuel cell. , FIG. 7 is a sectional view of an electrode end of a conventional fuel cell, and FIG. 8 is a perspective view of an electrode end of a conventional fuel cell. l... Fuel electrode, 2... Oxidizer electrode, la, 2a...
Electrode substrate, 4... Cell, 5... Separator, 9.
...Electrode end, 10...Spacer, ll...Bag seal, 12...Sealing material.

Claims (1)

[Claims] 1. A battery body in which a plurality of unit batteries having a pair of gas diffusion electrodes and an electrolyte layer disposed between these electrodes are stacked with separators interposed therebetween; A fuel cell comprising a supply and discharge device for supplying and discharging gas to and from the electrode, and the gas diffusion electrode is composed of a fuel electrode and an oxidizer electrode, each of which has a gas seal at its end parallel to the direction of the gas flow path. A fuel cell characterized in that a thermoplastic sealing material is inserted between the separator and the electrode end.