JPS62180963A - Manufacture of carbonaceous member for fuel cell - Google Patents

Abstract

PURPOSE:To efficiently obtain a complex electrode in which electrodes and a separator are integrated with each other, by disposing porous shaped carbon bodies having through holes, on both the sides of a gas-impermeable carbonaceous shaped body, and by heating them under pressure to harden them, and thereafter baking the bodies to carbonize them. CONSTITUTION:A water-soluble phenolic resin or the like, chopped carbon fibers or the like and water are mixed together to make a slurry. A sheet is made from the slurry and subjected to heat treatment to make a porous shaped carbon body 1 having through holes 2 nearly in the middle of the thickness thereof. A thermosetting resin liquid and graphite or the like are mixed together and subjected to molding or the like to make a shaped body 3 as a gas-impermeable carbonaceous separator. The porous shaped carbon bodies 1 are disposed in the grooves of the top and bottom of the shaped body 3 so that the through holes 2 of the bodies 1 extend perpendicularly across each other. The bodies 1, 3 are heated under pressure so that they are hardened. The bodies 1, 3 are then subjected to baking carbonization. The side surfaces of a complex electrode for a fuel cell are thus easily made gas-impermeable.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a method for manufacturing a carbonaceous member for a phosphoric acid fuel cell in which a porous carbon electrode and a gas-impermeable carbonaceous separator are integrally formed. Regarding.

``Prior art'' A fuel cell consists of a unit cell by arranging porous electrode plates carrying a catalyst on both sides of a matrix layer holding phosphoric acid, and each unit cell is connected in series through a separator plate. A predetermined stack structure is formed. The shape of porous electrode plates and separator plates can be divided into ribbed or flat plates, depending on whether or not they have gas flow grooves for passage of fuel and oxidizer, but these materials have heat resistance, chemical resistance, and electrical conductivity. Characteristics such as elasticity, thermal conductivity, and ease of processing are required, and carbon materials are useful as materials that meet these required characteristics.

In general, in a stack structure, the entire stack must be firmly clamped to reduce the contact resistance between the electrode plates and separator plates as much as possible, and the thickness of the electrode plates and separator plates must be adjusted to make the entire stack more compact. However, since carbon materials do not have sufficient mechanical strength, they may break during handling or compression during battery assembly.

For these reasons, by integrally forming the porous carbon electrode plate and the gas-impermeable carbon separator plate,
Attempts have been made to increase mechanical strength, reduce contact resistance, and facilitate battery assembly. For example, JP-A-60
There is a method of bonding a carbon-based porous electrode plate and a separator plate, or precursors of these members via an adhesive, as proposed in Japanese Utility Model Application No. 60-15759. However, during bonding, some of the adhesive may penetrate into the tissue structure of the porous electrode plate or flow into the gas flow grooves, locally damaging the porosity or clogging the grooves. may occur. Furthermore, because the gas flow grooves allow only the entire surface to be bonded, there is a drawback that the bond is strongly bonded.

From these viewpoints, the applicant has proposed a method of integrally joining, via a carbonizable material, a porous carbon molded body having a group of through holes approximately in the center of the thickness on both sides of a gas-impermeable carbon thin plate. (Japanese Patent Application No. 6O-290848). A group of through holes on the gunwale function as grooves for gas circulation.

"Problems to be Solved by the Invention" However, in order to prevent gas leakage from the side surface of the porous carbon electrode, it is necessary to perform an impermeability treatment.

Usually, the side surface of the electrode is impregnated with finger liquid or a material such as Teflon is used, but this method is difficult to work with, is inefficient, and may cause deposits.

The present invention provides a method for manufacturing an integrated composite electrode in which a gas seal is applied to the side surface of a porous carbon electrode using the above method (Japanese Patent Application No. 6O-290848).

``Means for Solving the Problems'' That is, the present invention involves kneading carbonaceous powder and thermosetting resin liquid and then forming it into a thin plate, and forming a layer on both sides of the thin plate-shaped carbonaceous molded body approximately at the center of the thickness. A porous carbon molded body having a group of through-holes in a part thereof is crimped in a carbon precursor state, and the thin plate-like carbonaceous molded body is attached to a side part parallel to the through-hole group 'f'.
This is a method for manufacturing a carbonaceous member for a fuel cell, which is characterized in that the carbonaceous member is heated and hardened under pressure in a mold having a predetermined shape, and then subjected to firing and carbonization treatment.

Carbonaceous powder such as graphite, coke, carbon black, etc. whose particle size has been adjusted in advance is mixed with a thermosetting resin liquid such as phenol type or furan type, and after uniformly kneading with a kneader, the kneaded product is molded or rolled. By rolling, a thin carbonaceous molded body having a predetermined thickness and shape can be obtained.

On the other hand, a porous carbon molded body can be obtained by combining carbon fiber chops and a thermosetting resin. For example, water-soluble phenol resin and carbon fiber chops are dispersed in water to form a slurry, and this slurry is injected into a mold of a predetermined shape to produce the product by applying a pressure molding method, a paper making method, etc. I can do it. In this case, the rod-shaped body is held at a predetermined position in the mold, and after molding, the carbon precursor state is
After the heat crosslinking and curing treatment, the rod-shaped body can be removed to form a group of through holes. As the material for the rod-shaped body 1, metal, Teflon resin, or the like, which can be easily removed from the molded body, is used. In addition, this through hole group has 50 to 60 holes.
Filling with a substance that decomposes and volatilizes at 0° C., such as polystyrene or paraffin, is preferable because deformation or damage to the through-hole group can be prevented during pressure bonding and subsequent processing such as heat curing.

The porous carbon molded body thus obtained is pressed onto both sides of the thin plate-like carbonaceous molded body. Further, a thin plate-like carbonaceous molded body is also attached to a side surface portion parallel to the group of through holes. That is, both sides of a thin plate-like carbonaceous molded body of a predetermined shape are sandwiched between porous carbon molded bodies having the molded body adhered to the side surfaces, and heat-hardened under pressure in a mold of a predetermined shape to form an integral piece. It is something that becomes.

Next, by heating in an inert atmosphere and firing and carbonizing, it is possible to manufacture a carbonaceous member for a phosphoric acid fuel cell in which the electrode plate and the separator plate are integrally joined.

"Function" In the present invention, an i-V plate-like carbonaceous molded body in an uncured stage and a porous carbon acid 1 form in a carbon precursor state are brought into pressure contact and heat-cured under pressure. Be strongly connected and integrated. This curing reaction is applied using flI,'
The conversion to gas-impermeable 1-bromine through i l-i performance and calcination carbonization gives gas-impermeable 60 performance to electric (prefecture side +'! Be manufactured.

=Example'' 10 parts of water-soluble phenol (ROI fat (IE Honrau Hippoort Co., Ltd. Ring Plyopheno, J-303) and 70 parts of carbon fiber chop (average diameter 5 denier, average length 8.■) was added to 20 parts of water and stirred to uniformly disperse it to form a slurry.The slurry was formed by a papermaking method and heat treated to form a 170mm square, 2.5 mm thick and 2.5 mm thick. A porous carbon molded body having 40 through-holes with a diameter of 1.5Rx approximately in the center was manufactured.

r, , ; :b, r1 hole group all have a diameter of about 1, 4.
A wm polystyrene rod was inserted.

Next, 100 parts by weight of liquid phenol resin cut-off condensate was added to the beveled part of 120 artificial graphite powders with an average particle size of 5 μm, and the mixture was thoroughly kneaded, and then rolled to a thickness of 0.5 parts and 7 m.
It was formed into a flat plate. The porous carbon molded body No. 11n is placed on both sides of this flat plate. The other side of the wire was coated with hair.Next, it was charged into a mold and heat treated at 150°C for 5 minutes under a pressure of 10kg□'fJ2, and after being heated and cured, it was removed from the mold: ) Tashi, 18
The curing process was completed by heating at 0°C for 5 hours.

The integrally assembled body thus obtained was heated in an inert atmosphere at 1300° C. for 1 hour and subjected to firing and carbonization treatment to produce an integral compounding electrode having the structure shown in the figure.

In the figure, I is a porous carbon electrode, and 2 is a through hole! L1.
3 is a part of a gas-impermeable carbonaceous separator.

It should be noted that all of the Boris dilene pellets inserted into the through holes were decomposed and volatilized during these heat treatments.

This integrated composite 7 [pole 1W degree 200°C 1 pressure 1kg
The result of measuring the amount of leakage by flowing air under the condition of /cm' was 10-'' (cm37cm2-min).In addition, the temperature was rapidly raised and lowered from room temperature to 220℃. Although the test was repeated 20 times, no peeling (or spalling) between the electrode part and part of the separator was observed.

``Effects of the Invention'' As is clear, the method of the present invention can easily perform gas impermeability treatment on the side surface of the electrode of a composite electrode in which the electrode part and part of the separator are integrated. . Furthermore, since the sintering and carbonization process is performed after the integral bonding, the number of sintering steps can be reduced. Therefore, it is possible to extremely efficiently manufacture a composite electrode in which the electrode part of a phosphoric acid fuel cell and a part of the separator are integrated.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a schematic diagram of a composite electrode in which an electrode part after calcination carbonization treatment and a part of a separator are integrated according to the present invention. 1. Porous carbon electrode, 2. Through-hole group, 3. Part of gas-impermeable carbonaceous separator.

Claims (1)

[Claims] 1. After kneading carbonaceous powder and thermosetting resin liquid, molding it into a thin plate shape, and forming a porous carbon molded body having a group of through holes approximately in the center of the thickness on both sides of this thin plate-like carbonaceous molded body. , the thin carbonaceous molded body is crimped in a carbon precursor state, and the thin plate-like carbonaceous molded body is adhered to the side surface portion parallel to the through hole group, and then heated and hardened under pressure in a mold of a predetermined shape, followed by firing carbonization treatment. A method for manufacturing a carbonaceous member for a fuel cell, characterized in that: