JPS58166639A - Fuel cell - Google Patents

Abstract

PURPOSE:To improve strength of an electrode catalytic layer, by mixing phosphoric acid resistant fiber of matrix material, silicon carbonide fiber, graphite silicon fluorid fiber, etc. in a catalytic active ingredient of a pair of electrodes having a catalytic active gradient. CONSTITUTION:Electrode catalytic powder holding noble metal to carbon powder, matrix material fiber, silicon carbonide fiber, graphite silicon fluorid fiber, etc. are mixed, added with water and kneaded by a kneader or the like. Polytetrafluoroethylene dispersion of an organic binder is added to the above kneaded material again kneaded. This kneaded material is applied to an electrode base material, dried and fired to form an electrode plate. In this way, strength of an electrode catalytic layer can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel cell using phosphoric acid as an electrolyte.
Item 11 relates to a fuel cell in which phosphoric acid-resistant fibers are mixed in a catalytically active component to improve the strength of an electrode having a catalytically active component on a conductive base material.

Conventionally, electrode plates used in fuel cells using phosphoric acid as an electrolyte are made by mixing an electrode catalyst in which active ingredients are supported on carbon powder with polytetrafluoroethylene, an organic binder, on a conductive substrate. It was formed by coating and firing. The applied electrode catalyst is bound to the conductive substrate by the binding force of polytetrafluoroethylene alone, so the binding force with the conductive substrate is weak, so the electrode catalyst may peel off or carbon powder particles may form. Since the binding force between the electrode plates is weak, cracks may occur in the electrode plate catalyst layer.

An object of the present invention is to provide a fuel cell with improved strength of the electrode catalyst layer.

The present invention is an enhancement of a phosphoric acid resistant fabric in a catalytically active component on a conductive substrate.

Substances that improve the strength of electrode catalysts containing catalytically active components include those that have phosphoric acid resistance, high temperature (190C ~
It is thought that it is compatible with phosphoric acid (200C), does not inhibit the activity of the catalyst, has an affinity with the electrode catalyst, and is a fiber.As a result of examining various substances that satisfy these conditions, we found that It has been found that inorganic materials such as carbides and oxides are suitable as materials that can withstand phosphoric acid at high temperatures.

Among them, it has been found that 1 trix material, fluorinated graphite, silicon carbide fiber, etc. are suitable. If fibers of the matrix material are present in the catalyst layer of the electrode plate, it is expected that a three-phase interface will also be formed within the catalyst layer, which is thought to contribute to improved performance. For these reasons, electrode contact] 11KK
An attempt was made to form an electrode plate by adding phosphoric acid-resistant woven wire, coating it on a conductive base material, and firing it.9. As a result, the strength of the electrode plate catalyst layer and the performance of the electrode plate were also improved.

Example 1 The following electrode catalyst was prepared by supporting noble metals on carbon powder, and 8 g of the electrode catalyst powder was mixed with 5j141 IJ lux fiber, water was added thereto, and the mixture was sufficiently kneaded in a kneader. 8g of organic binder polytetrafluoroethylene dispersion binder was added to the mixture and kneaded again.The 1111 mixture was applied to the base material of the electrode, and then dried and fired to obtain an electrode plate. Ta. In the conventional method, 8 g of electrode catalyst powder was mixed with polytetrafluoroethylene flltf14 and water using a kneader. The subsequent steps were performed in the same manner as the method of the present invention. 11th! ! I
2 shows the results of an impact test of the nine electrode plates obtained according to the present invention and the electrode plates pierced with Ij4 according to the conventional method. In this impact test method, an electrode plate is fixed and a hard ball of a certain weight is dropped onto the plate from a certain height, and the strength is compared based on the amount of electrode catalyst that falls off. The calculation formula is shown below.

Table 1 shows the results of the experiment. The weight change of the electrode plate formed by the conventional method is 35%, but in the electrode catalyst!
The weight change of the galvanic single plate formed by adding TRIX material fibers was 2%, and the strength was significantly improved. In addition, the performance of the electrode plate formed by the present invention and the electrode plate formed by the conventional method was evaluated by supplying air in 190R phosphoric acid and measuring the monopolar potential as an air electrode during running. In the figure, the symbol i indicates the current density-potential characteristic of the electrode plate obtained in this example, and the symbol 2 indicates the current density-potential characteristic of the electrode plate obtained by the conventional method. As is clear from this figure, it was found that the performance was improved when the electrode plate prepared according to the present invention was used. Factors that improve this performance include (1) IJ lux material fibers are included in the electrode catalyst layer, so the fibers retain phosphoric acid; (4) IJ lux absorbs phosphoric acid from the surface in contact with the electrode catalyst layer It is considered to be a rounding that creates 4 three-phase interfaces within.

Example 2 8 g of an electrode catalyst and silicon carbide fiber SGT were mixed, water was added thereto, and 1 g of polytetrafluoroethylene was added and kneaded. The value process is
An electrode plate was obtained by the same method as in Example 1. An impact test was conducted on the running electrode plate obtained above, and the results shown in Table 1 were obtained. From Table 1, it was found that the addition of silicon carbide fibers improved the strength.

According to the present invention shown in Table 1, in addition to the effects described above, the following effects can be obtained.

In other words, the strength of the running electrode plate by adding 17Tx material fiber and silicon carbide LA#1 to the electrode catalyst is 10 times stronger than that of the electrode plate obtained by the conventional method, and the battery performance is improved. .

[Brief explanation of the drawing]

The figure is a performance ratio IIR diagram using the conventional method and the electrode plate of the present invention. Continued from page 1 ■ Applicant Hitachi Chemical Co., Ltd. 177-2-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo

Claims (1)

[Scope of Claims] t. A fuel cell comprising a pair of electrodes having a catalytically active component on a porous conductive substrate and an electrolyte retention matrix disposed between the electrodes, wherein the catalytic component contains a catalytically active component. A fuel cell characterized by mixing phosphoric acid fibers. 2. A fuel cell according to claim 1, wherein the phosphoric acid-resistant fiber is made of an IJ material. 1. In claim 131, the phosphoric acid-resistant fiber is made of silicon carbide. A fuel cell characterized by: Table 1. The fuel cell according to claim 1, wherein the phosphoric acid-resistant fiber is made of fluorinated graphite fiber.