JPS585977A - Manufacture of bipolar plate for alkali water solution electrolyte type fuel cell - Google Patents

Abstract

PURPOSE:To manufacture a carbon bipolar plate excellent in corrosion resistance mechanical strength and gastightness inspite of high conductivity by using compound powder, wherein graphite powder is stuck to the surface of an alkali- resisting resin. CONSTITUTION:A carbon plate is obtained by a method, wherein graphite powder having a granular diameter under 180mum is given an affinity treatment, ''Gra-Compo'' complex powder stuck to polyphenylneoxide resin having a granular diameter under 280mum fills up a forming metal mold to be pressed at 880 deg.C. For an alkali-resisting regin, besides that said above, a polysulfonic ether resin polyallylether, and a polybutadiene resin are desirable, while a stearinic acid treatment, and a phenol resin treatment can be applied as an affinity treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing longitudinal bipolar plates for use in alkaline aqueous electrolyte Nada fuel cells.

In the configuration of a fuel cell consisting of a plurality of single cells, a so-called bipolar plate is used in which a gas separator plate that separates the gas chamber and electrolyte chamber of each single cell also serves as a conductive plate that connects the electrodes of adjacent cells. This bipolar plate is desired to have high electrical conductivity, sufficient mechanical strength, and no gas leakage through the plate. Bipolar plates are usually made of carbon, and are made by mixing graphite powder and a binder, filling a molded metal, and hot pressing at a temperature above the curing temperature or melting temperature of the binder.

However, such carbon bipolar plates are mostly used in acidic electrolyte layer fuel cells, and have not been used for alkaline aqueous electrolyte layer fuel cells. There are nine types of alkali-resistant carbon plates that are made of furan resin or divinylbenzene resin N as a binder. Alkaline water fl/liquid electrolysis't
Under the operating conditions of the M fuel cell, it did not have sufficient corrosion resistance, and collapsed or electrical components occurred after about 1000 hours.

In carbon bipolar grades, if the amount of binder is large, the conductivity will be low, and if the amount of binder is small, the corrosion resistance will be inferior in terms of mechanical strength and gas leakage. Therefore, an alkaline aqueous solution that satisfies these characteristics It has not been possible to obtain carbon bipolar plates for electrolyte fuel cells in the past, but the present invention provides a carbon bipolar plate for use in alkaline aqueous electrolyte fuel cells that satisfies both of the above-mentioned properties required for this purpose. The purpose of the present invention is to provide an O1m manufacturing method.

This objective is achieved by thermoforming a composite powder made by attaching good and bad lead powder to the surface of an alkali-resistant resin to increase its surface affinity with the resin through affinity treatment.

Examples of alkali-resistant resins include polysulfone 1111° polyphenylene oxide resin, polyallyl ether resin, polybutadiene resin, and epoxy resin.

Polyethylene resin, polypropylene resin, polysalt J'
Vinyl resin, polytetrafluoroethylene resin, polytetrafluoroethylene-hexafluoropropylene resin can be used. Stearic acid treatment I
1. It is applied to phenolic resin treatment, polyester treatment, process oil treatment, naphthenic oil treatment, fatty acid treatment, water glass treatment. The powder is commercially available, for example, under the trade name "Guracompo" (Nippon Graphite Industries Co., Ltd.).

The present invention will be described below with reference to test examples and figures.

It was filled and pressed at 880°C to obtain a carbon plate sample.

Indicated by lm18. The gas leakage amount is the amount of hydrogen permeated in the thickness direction of a 5-inch thick sample at a pressure of 2 and 9 f/ld. From this, it was found that a resin content of less than 10 - causes gas leakage, and a resin content of 1201 or more causes an increase in specific resistance, so a resin content in the range of 10 to 20% is appropriate. Figure 2 shows the change in resistivity when the resin content is 15 - and the content of graphite powder with a particle size of 60 μm or less is changed. Line 21 shows the change in elastic modulus. ) If the content of graphite with a diameter of 60 μm or less is less than 80, the flexural modulus increases rapidly, making it difficult to use, and if it exceeds 80 qk, the specific resistance increases, so it has been found that 80 to 80 is appropriate. 1 for the total amount
5 weight-of! A mold was filled with ``Guracompo'' powder, which was adhered to polyphenylene oxide resin and polysulfone resin with a particle size of sOμm or less, and heated at 880°C.
A carbon plate sample was prepared by pressing the carbon plate. These and conventional furan resin and divinylbenzene resin were each added by weight of 15%.
A carbon sample used as a binder was immersed in an 80% KOH aqueous solution at 0°C for a long time in an oxygen bubbling bottle, and the change in strength was measured. The results are shown in Figure 3. In the figure, @81 is polyphenylene oxide as the resin, line 8
Line 88 is a sample of a conventional alkali-resistant carbon plate made using a furan resin and line 84 is a sample of a conventional alkali-resistant carbon plate using a divinylbenzene resin. That is, conventional carbon plates are good at the initial stage, but cracks occur after 500 to 1000 hours and the bending strength becomes zero. On the other hand, the carbon plate according to the present invention does not deteriorate even after 2000 hours.

In conventional alkali-resistant carbon plates, the resin itself does not have sufficient alkali resistance under the conditions in which fuel cells are operated, and since graphite and resin are mechanically mixed, the mixture may be uneven. However, it is thought that when the immersion time in the alkaline solution becomes longer, the parts with relatively less resin swell, leading to the occurrence of cracks. On the other hand, in the carbon plate according to the present invention, the resin and graphite powder are mixed very uniformly, so there is no local unevenness in quality, and therefore the carbon plate has mechanical strength even with a small amount of resin. 11- Satisfied 1
It seems that something without gas leakage can be obtained.

As described above, the present invention provides surface KM of alkali-resistant resin.
By using gold powder as raw material with lead powder attached,
This makes it possible to manufacture carbon bipolar plates that have good corrosion resistance, mechanical side gas leakage resistance, and high electrical conductivity, and is extremely effective for To and bipolar plates for alkaline aqueous electrolyte fuel cells. Applicable.

[Brief explanation of the drawing]

FIG. 11 is a diagram showing the relationship between the resin content in the bipolar plate material used in the method according to the present invention and the characteristics of the carbon plate;
FIG. 2 is a diagram showing the relationship between the graphite powder content and carbon plate with the same particle size of <60 μm or less, and FIG.
A diagram showing the change in bending strength of the carbon plate according to the example and the conventional corrosion-resistant carbon plate due to immersion in a KOH aqueous solution Q81...Sample using polyphenylene oxide w fat. 82...Sample using polysulfone resin.對聚合f (%) Pure and dirty, 1 son, 1, and 1 people! (%) *3
Figure: Ukezuke Ginko (h)

Claims (1)

[Claims] 1) An alkaline aqueous electrolyte fuel characterized by thermoforming a composite powder obtained by adhering graphite powder whose surface affinity with the resin is increased by affinity treatment to the surface of an alkali-resistant resin. A method for manufacturing bipolar plates for batteries. 2. In the method according to claim 1, the alkali-resistant resin may include polysulfone resin, polyphenylene oxide resin, polyallyl ether resin, polybutadiene resin, epoxy resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyvinyl chloride resin, A method for manufacturing a bipolar plate for a fuel cell made of an alkaline aqueous electrolyte, which uses either a tetrafluoroethylene resin or a polytetrafluoroethylene-hexafluoropropylene resin. 8) In the method according to claim 1 or 2, the affinity treatment includes stearic acid treatment, phenol resin treatment, and polyester treatment. In the method according to any one of claims 1 to 8, the method according to any one of claims 1 to 8, in which the process oil treatment, naphthenic oil treatment, fatty acid treatment, or water glass treatment is performed. 6 below electric
Graphite powder with a particle size of 80 to 80 - less than 0μ! The total amount of resin is ICj for alkali-resistant resin of 80 μ group or less.
-20- A method for producing a bipolar plate for a fuel cell with an alkaline aqueous electrolyte layer, the method comprising using a sound detection powder adhered as shown in FIG.