JPS5812267A - Gas separator for fuel cell - Google Patents

Abstract

PURPOSE:To simplify manufacturing of the said gas separator and prevent generation of its deformation by fitting a carbon paper laminating body to which water repellent treatment is applied on both the front and rear of a carbon substrate. CONSTITUTION:A substrate 4 is formed by mixing resin powder in graphite powder, pressure-heating-molding them, and providing opposed side edges 2 and 3 on both the flat front and rear in the mutually crossed direction. Simultaneously porous gas passages 6 and 7 are formed by fitting the laminating body of carbon paper 5 that is immersed in a fluororesin dispersion, withdrawn, and heat-treated at the bonding temperature of the fluororesin between the side edges 2 and 3. Besides, a cell pile is formed by laminating with an electrolytic matrix and a unit cell consisting of positive and negative electrodes. As a result, manufacturing of the said gas separator can exceedingly be simplified by using the carbon paper laminating body 5 instead of a number of gas supply grooves.

Description

[Detailed description of the invention] The present invention relates to improvements in gas separation plates for fuel cells.

Cafbon gas separation plates for matrix fuel cells (which use acidic electrolytes) are used to separate the cathode (hydrogen electrode) and anode (matrix fuel cells).
It has the function of supplying each reaction gas to the back side of the air electrode (air electrode) and the function of connecting conductor between the unit cell consisting of the negative and positive gas electrodes and i-trix.

Furthermore, for the former function, it is necessary to be non-porous in order to completely separate hydrogen and air.

Such gas separation plates are made by mixing graphite powder with binder powder such as phenol resin, and after pressurizing and heating molding, the plate is heated at high temperature (approximately 1000°C) to carbonize the binder.
It is created through long-term heat treatment.

As shown in the plan view of FIG. 1 and the cross-sectional view of FIG. A large number of hydrogen gas supply grooves (B) and air supply grooves (C) are formed in the direction, but the manufacturing process is difficult due to the complexity of mold creation. When this happens, the filling of graphite powder becomes uneven, resulting in uneven thickness, and the large number of grooves (B) and (C) causes deformation of the separation plate, and especially warpage, resulting in poor end-stopping. .

The present invention forms porous gas passages using a stack of water-repellent treated carbon papers instead of the large number of gas supply grooves that cause such defective products. An example will be explained with reference to the figure.

The gas separation plate (1) according to the present invention has opposite side edges [! l+! l and 1sl1
A stack of a non-porous carbon substrate (4) on which 31 is formed and a carbon paper (6) treated with water repellent is placed on the opposite side edge +2) f! 1 and +3) porous gas passage fitted into the fil barrier +so'1. It consists of +.

The substrate (4) is made by a normal method, but both the front and back sides are flat except for the opposite side edges, and there are no many grooves as in the conventional case, so it is easy to make and does not have any shape or warpage. This rarely occurs.

The carbon paper area used as the gas passage +111+71 is immersed in a fluororesin dispersion, pulled up, and then heat-treated at the binding temperature of the fluororesin, similar to the carbon paper (waterproof layer) lining the catalyst layer in the gas electrode. The content of fluororesin in the electrode waterproof layer is about 40 -, while in the case of the carbon of the present invention it is about 5 -, which does not significantly impair the conductivity and porosity of the carbon paper (6). .

This carbon paper (-) has a thickness of about 0.4 ws, so if the height of the opposite side edge +21+31 of the substrate (4) is about 2 swQ degrees, then 5 sheets of this can be stacked and used. .

FIG. 4 shows a cross-sectional view of a battery stack in which gas separation plates +11 of the present invention and unit cells are alternately stacked, and this is shown in FIG.
This is the case when the cross section is taken along a line.

The unit cell is the cathode (8) electrolyte (IJ Lux 9) and the anode (k), and the cathode (8) is carbon paper (m).
Hydrogen gas is supplied from the plane of the paper through the hydrogen gas passage (6) t-, which is made up of a heavy body, and the same air passage (7) is provided to the anode.
), air is supplied from a direction perpendicular to the plane of the paper, and these reaction gases react via the matrix ill to generate electrical energy.

Regarding the supply of reaction gas, since the porous gas passage of the present invention has greater ventilation resistance than the conventional groove method, it is necessary to increase the supply pressure. For example, in the case of hydrogen gas, it is necessary to increase the supply pressure to
In the case of air, it requires about 7 to 10 times.

In the gas separation plate according to the present invention, a porous gas passage is formed by a stack of water-repellent carbon paper instead of a large number of gas supply grooves. Since it only needs to be fitted between opposing edges formed on both sides in mutually intersecting directions, manufacturing is simple and does not require complicated molds, and is particularly effective against deformation and warping of the separation plate caused by a large number of grooves. This eliminates the occurrence and improves the extraction and delivery times.

In addition, the carbon paper that makes up the gas passage has been pre-treated with a water-repellent treatment, so even if electrolyte or generated water leaks out, breathability will not be affected, and the gas supply pressure can be controlled by using the conventional gas groove. It fully demonstrates its function by increasing it compared to the method.

[Brief explanation of drawings]

Figure 1 is a plan view of a conventional gas separation plate, Figures 2 (a) and (b)
) are cross-sectional views taken in directions perpendicular to each other in FIG. 1; FIG. 6 is an exploded perspective view of the gas separation plate of the present invention, and FIG. 4 is a partial sectional view of a battery stack equipped with the gas separation plate of Lee's invention. DESCRIPTION OF SYMBOLS 1... Gas separation plate, 2.2 and 3.6... Opposing side edge, 4-substrate, 5... Carbon paper, 6.7...
・Gas passage, 8.10...Yin-yang gas electrode, 9...Matrix Figure 2 (d+ mouth +b+
donkey 11

Claims (1)

[Claims] ■ A porous structure made of a carbon substrate with opposite side edges formed on both the front and back sides in mutually perpendicular directions, and a stack of water-repellent carbon paper fitted between each of the opposite side edges. 9. A gas separation plate for a fuel cell, comprising: a gas passage;