JPS6086013A - Porous flat plate having electrical conductivity - Google Patents

Abstract

PURPOSE:To prepare an electrode for fuel cell having improved characteristics, by setting porous carbon having a three-dimensional network structure in a cavity, subjecting chemically active two kinds os solutions to reaction injection molding, calcining it. CONSTITUTION:Melt of naphtha tar pitch is sprayed upon porous Al, the temperature of a furnace is then gradually raised, and the melt is calcined at 800 deg.C at the maximum, to prepare porous carbon having >=85% voids. It is set in a cavity of mold with a rib. The solution A consisting of a polyol composition containing a blow agent is blended with the solution B of isocyanate, injected to the mold, expanded, and set to give an electrode base plate with a rib. It is then calcined in an air atmosphere at 220 deg.C, kept then at 800 deg.C under nitrogen gas purge, and calcined by raising the temperature gradually to 1,800 deg.C. An electrode plate for fuel cell having high energy conversion efficiency, improved corrosion resistance, electrical conductivity and combustibility of fuel, is obtained.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention has a three-dimensional network structure and a porosity of 60 to 80%, and has excellent corrosion resistance and conductivity due to electrolytes, as well as combustibility of fuel. The present invention relates to a conductive porous flat plate suitable as a fuel cell electrode with excellent properties, and a method for manufacturing the same.

[Background of the invention]

Conventionally, electrically conductive porous flat plates have not been developed as electrodes for large-capacity fuel cells, and no one that has particularly high energy conversion efficiency and can be produced at low cost has been provided. In other words, research and development of fuel cells for the electric power industry began around 1972 at United Technology and other companies in the United States, and a pilot plant is currently in operation, but the output is small, around 4,500 kW. . Commercial high-output power plants require the development of high energy conversion efficiency and economical production technology. Although methods for manufacturing large-area electrodes, which are the object of the present invention, have been studied on a trial basis, all of them have the disadvantage that they require a large number of man-hours and are not suitable for use in the electric power industry.

[Purpose of the invention]

The present invention solves the above-mentioned drawbacks, and its purpose is to provide a conductive porous flat plate that has high energy conversion efficiency and can be produced economically, and a method for manufacturing the same.

[Summary of the invention]

The conductive porous flat plate of the present invention has continuous permeability of fuel gas, which is necessary as an electrode for fuel cells.

It is characterized by having a three-dimensional network structure and a porosity of 60 to 80% in order to have flammability through the electrolyte solution and conductivity as a carrier of generated electrons. Furthermore, the method for producing a conductive porous flat plate of the present invention involves reaction injection molding of porous carbon, which is prepared by treating a porous body having a three-dimensional network structure made of resin or metal with molten pitch and then firing it. It is characterized in that it is placed in a cavity with ribs, then reaction-injected with two types of chemically active stock solutions to form a lip-equipped electrode base plate, and then this lip-equipped electrode base plate is fired.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings. First, an outline of this embodiment will be explained.

The method of manufacturing a conductive porous flat plate with a coating according to the present invention consists of the following two main steps. That is, in the first step, as shown in FIG. 1A or B, the porous resin 1 or the porous gold pA2 is thermally sprayed or immersed in molten pitch (3), and then subjected to the firing operation (4). This is a process of manufacturing porous carbon 5 with a porosity of 85% or more, and the second process is a second process.
As shown in the figure, the porous carbon 5 is set in a molding ribbed cavity 6, and reaction injection molding of two types of chemically active stock solutions (this is performed using an insert mold RIM).
In this step, a conductive porous electrode 10 is manufactured through step 7 of forming an electrode original plate 8 with lips, followed by operation 9 of firing the electrode original plate 8 with lips.

Hereinafter, the present invention will be explained in more detail with reference to specific examples.

Example 1 Porous aluminum was thermally sprayed with a naphtha cool pitch melt kept at 400 C or more for more than 1 hour using a gun equipped with a spray nozzle, and then heated gradually from room temperature in a firing furnace until it reached a maximum temperature. Porous carbon with a porosity of 90% was obtained by firing the carbon to 81 JOU for a total of about 10 hours. Next, set it inside this porous carbon lipped cavity. The reaction injection molding machine uses chemically active two
The Avffl tank contains a polyol composition containing a blowing agent Freon 1 (-11710% by weight), and the B liquid tank contains Incyanate (4,4'
- Diphenylmethane diisocyanate), in this case, a modified LRM-R25 manufactured by Cincinnati Miraculo (trade name) is used to collide and mix liquids A and B, and then inject them into the mold. and harden the foam.
An electrode original plate with lips was obtained. This electrode original plate with lip is 22
0C in an air atmosphere for 4 hours, then fired at 800C for 4 hours under a nitrogen gas burn (-, then gradually raised the temperature and fired at 1800C for 4 hours, then lowered the temperature. A three-dimensional mesh electrode plate having pores, that is, a conductive porous flat plate was obtained.

The various properties of this electrode were measured using conventional methods, and the values shown in number 1 in the table below were obtained. That is, the molded product density is 810
Kf // PL' + porosity 63% 2 bending strength 145 (-) A relatively rigid flat plate was obtained, electrolyte resistant,
It showed excellent properties in terms of gas permeability. Further, FIG. 3 is a schematic enlarged view of the structure of the conductive porous plate obtained in this example. In the figure, numeral 21 indicates porous carbon having a three-dimensional network skeleton structure.

Table Examples 2 to 5 The first step in this case is shown in FIG. 1C. That is, a porous resin 11, such as Scotto Felt manufactured by Prigiston Tire (trade name), is set in a mold, slurry-like gypsum 12 is cast and hardened, and the resin is thermally decomposed and removed by firing 13. Next, the naphtha tar pitch melt 15 held at 400 °C for more than 1 hour was poured into a mold, followed by firing 1.
After 6, a gypsum removal operation 17 using jet water or mechanical vibration such as shot blasting was performed to obtain porous carbon 5 with a porosity of 92%.

Next, the second step uses the same reaction injection molding machine and mold as in Example 1, and changes the injection amount to achieve a molded product density of 700 to 2.
A light foam structure molded product with a temperature change of up to 50 K/,/ was obtained,
This molded product was fired in the same manner as in Example 1 to obtain a conductive porous flat plate as an electrode plate.

The characteristics of these electrode plates are as shown in signals 2 to 5 in the table above. That is, the porosity shows 66 to 78%,
Accordingly, the molded product density ranges from 690 Kf/i to 260 Kf/i.
b/-, and the bending strength also decreases from 155 Kg/cd to 95 Kg/cd, but there is no problem in practical use (of course, the electrolyte resistance and gas permeability are also excellent.

In these examples, a chemically active double-base material and a hardening material are used to produce polyurethane, nylon, polystyrene, epoxy, polyester, and silicone as porous carbon molding resins that function as framework materials. A liquid composition of can be used.

It is also possible to pre-mix a foaming agent into the chemically active raw material so that the molded product becomes a foamed structure during reaction injection molding, increasing the speed of carbonization and porosity during firing. can.

Further, by arranging a large number of molds for one raw material supply equipment unit and simultaneously obtaining a large number of foam molded products, it is possible to economically produce a conductive porous flat plate.

Through the above explanation, a new method for manufacturing a porous electrode plate with conductive lips that has excellent performance as an electrode for fuel cells and is effective as a large-capacity electrode for electric power business has been established. In other words, a method for producing porous carbon with a high porosity as the framework structure of the electrode plate, and a new reaction injection method for providing dense pores (60 to 80% porosity) from the viewpoint of fuel gas combustion efficiency. By using a molding method to form a foam structure, it does not cause deformation such as warping under low pressure, and has excellent gas permeability, electrolyte resistance,
It also showed excellent properties in terms of bending strength.

In addition, through these embodiments, the density distribution of the porous electrode plate, which conventionally requires a large area, has a variation of 001 to 01, resulting in a density of output current, which is disadvantageous for commercial use. The density distribution is 001 to o, 0
It was possible to obtain a uniformity of 2 and a stable output current.

〔Effect of the invention〕

As is clear from the above description, the conductive porous flat plate according to the present invention has good energy conversion efficiency, and the manufacturing method thereof is suitable for large-capacity applications and has excellent economic efficiency.

It goes without saying that the present invention is not limited to the embodiments described above.

[Brief explanation of the drawing]

Figure 1 is a flowchart showing the first step of manufacturing porous carbon, Figure 2 is a flowchart showing the manufacturing process of a conductive porous flat plate, and Figure 6 is a skeleton obtained in an example of the present invention. Enlarged schematic 21 showing porous carbon having a structure: a porous flat plate having a three-dimensional network structure. Representative Patent Attorney High Column Akio-4゜51 Figure 6 笥 2 Figure￥3 Figure

Claims (1)

[Claims] 1. An electrically conductive porous flat plate having a three-dimensional network structure and a porosity of 60 to 80%. 2. Porous carbon, which is produced by treating a porous body made of resin or metal with a three-dimensional network structure with molten pitch and firing it, is placed in a ribbed cavity for reaction injection molding, and then heated with a chemically active material. 1. A method for producing a conductive porous flat plate, comprising firing a lip-equipped electrode base plate formed by reaction injection molding of two types of stock solutions. 6. The method for producing a conductive porous flat plate according to claim 2, characterized in that a blowing agent is mixed in advance into the stock solution for reaction injection molding.