JPS6095863A - Fuel cell - Google Patents

Abstract

PURPOSE:To increase the safety and the reliability of a fuel cell by increasing the airtightness between the edge seal area of a rib electrode and a separator so as to prevent the mixing of a fluid fuel with fluid oxidant which might result in heat generation or the deterioration of the characteristics of the fuel cell by packing a heat-resistant acid-proof resin between the edge seal area and the separator. CONSTITUTION:In each unit cell, a fluorine resin 4 used as a heat-resistant acid-proof resin is packed between the edge seal area of a rib electrode 2 and a separator 3. Owing to the above constitution, concave and convex areas existing in the surface of the edge seal area of the rib electrode 2 are absorbed and the close contact between the edge seal area and the separator 3 is achieved thereby increasing the airtightness between them. Accordingly a fluid fuel (B) is prevented from being mixed with a fluid oxidant (C) by preventing any development of gas leakage, thereby preventing any heat generation in a fuel cell stack and any deterioration of the characteristics of a fuel cell which might result from the mixing of the fluid fuel (B) with the fluid oxidant (C). Consequently, it is possible to obtain a fuel cell of high safety and reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fuel cell, and particularly to a fuel cell in which airtightness around the end of a ribbed electrode can be improved.

[Technical background of the invention and its problems]

2. Description of the Related Art Conventionally, fuel cells have been known as devices that directly convert energy contained in fuel into electrical energy.

This fuel cell usually has a pair of porous electrodes sandwiching an electrolyte, and a fluid fuel such as hydrogen is brought into contact with the back surface of one electrode, while a fluid oxidizer such as oxygen is placed on the back surface of the other electrode. When the fuel and antioxidant are supplied, electrical energy is extracted from between the electrodes using a gas chemical reaction. Electrical energy can be extracted with as high conversion efficiency as possible.

FIG. 1 shows, in a vertical cross-sectional perspective view, an example of the structure of a ribbed electrode type fuel cell based on the above principle and using phosphoric acid as an electrolyte. In the figure, the unit cell is a pair of ribbed electrodes 2 made of ordinary carbonaceous material, which have a plurality of grooves regularly arranged in parallel in directions perpendicular to each other, sandwiching IJ wax. A plurality of Lit cells are stacked to form a fuel cell stack. Here, these grooves form flow paths for fluid fuel and fluid oxidant, respectively. In fact, when each of the above m cells is to be laminated, a layer 3 having conductivity and no gas permeability is sandwiched between each unit cell and laminated.

In this state, each laminated cross-section is hermetically sealed, leaving only the openings at both ends of the groove of the ribbed electrode 2, to form a laminated cell. Therefore, the peripheral portion of the end of the ribbed electrode 2 (hereinafter referred to as an edge seal portion) needs to be sealed to improve gas permeability. Therefore, conventionally, unit cells each having an edge seal applied to the ribbed electrode 2 are stacked and tightened by applying pressure to fix the cells to form a fuel cell stack.

Naturally, in the above-mentioned fuel cell stack, airtightness between the edge seal portion and the separator 3 cannot be maintained, and gas leakage causes mixing of the fluid fuel and fluid oxidizer, resulting in heat generation and deterioration of cell characteristics. occurs. Figure 2 shows this situation in a conceptual diagram. 1. When fluid fuel B and fluid oxidizer C are mixed due to leak A, these reactants no longer participate in power generation. , not only the power generation efficiency decreases but also an exothermic reaction occurs.If this mixed state flows into the cell, it burns within the cell and generates heat, and IVi due to the local decrease in power generation efficiency. Non-uniformity of flow density 11E° occurs.Furthermore,
C1 Constant high temperatures will promote deterioration of the catalyst. Furthermore, if mixed combustion occurs within the manifold, there is a risk that the signal line will be damaged, making it impossible to monitor the operating status of the fuel cell stack.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and its purpose is to improve the edge seal part of a ribbed electrode.
The object of the present invention is to provide a highly safe and reliable combustion battery by improving airtightness between the fuel cell and the separator to prevent heat generation and characteristic deterioration due to mixing of fluid fuel and fluid oxidizer.

[・Summary of the invention]

In order to achieve the above object, in the present invention, heat-resistant and acid-resistant 4.)1 fat is filled between the ribbed i1 (pole edge seal part and 7)Q regulator in the fuel cell stack described above, and the edge seal part 1. We have removed the gap between the
The fee will be ¥1”.

′ [Example of actual invention] An embodiment of the present invention shown in the drawings will be described below.

FIG. 3 shows an example of the configuration of a j4j cell in a fuel cell according to the present invention. The same parts as in FIG. I will only describe the parts.

In other words, Fig. 1 shows a structure in which a fluororesin 4 is filled between the edge seal part of the ribbed electrode 2 and the seven-layer electrode 3 in the unit cell shown in Fig. 2 as a resin having heat and acid resistance. This is what I did. Here, the iat resin 4 is a heat-resistant, phosphoric acid-resistant fluororesin, such as PTFE.
, FEP.

PFA etc. (1 fluorocarbon resin is used.

On the other hand, as an alternative method for filling the resin 4 in the above method, the following method can be considered.

(,) At the above-described unit/cell stacking stage, a method of applying resin 4 paint on the surface of the edge seals and parts of several ribs and 1 pole 2, and then aBing the separator 3 and upper cells before the paint dries and hardens. .

(b) A method of impregnating the edge seal portion of the ribbed electrode 2 with resin 4 in addition to the unit cell lamination step described above, and laminating the separator 3 and the upper cell before the resin 4 hardens.

(e) In the unit cell fn lamination step described above, the film or sheet made of the resin 4 is placed on the ribbed electrode 2.
A method in which Teflon is sandwiched between the edge seal portion and the separator 3, heated to semi-melt it at Teflon decomposition temperature (170 to 200°C), and then laminated one after another.

By this method, in a fuel cell stack configured by stacking a plurality of bottom cells filled with resin 4 between the edge seal portion of the ribbed electrode 2 and the separator 3, the ribbed electrode 2 The unevenness existing on the surface of the edge seal part is absorbed, the edge seal part and the separator 3 are brought into close contact, and the gap created between them is removed to improve the airtightness between them.
) can be used. Therefore, it is possible to eliminate the above-mentioned SOF leak, prevent I'c L from mixing the fluid fuel B and the fluid oxidizer C, and solve the problems of heat generation in the fuel cell stack and deterioration of cell characteristics based on this. It becomes possible,
A highly safe and reliable battery can be obtained.

The table below shows a comparison of the heat generation and cell characteristics of the conventional ll, , l+ fuel cell stack and the fuel cell stack of the present invention.

〔table〕

In addition, in the above actual AI example, we talked about the "staining" of a ribbed electrode type fuel cell, but what about the "staining" of a ribbed electrode type fuel cell? - It can also be applied to leak prevention between a cell and a separator in a type fuel cell.

In the above, we have described a fuel cell using phosphoric acid as the electrolyte, but it can also be applied to a battery using something other than phosphoric acid as the electrolyte.

Furthermore, although a fluororesin was used as the resin having side heat acid resistance in the above, rigidity, 1. , j. Of course, other 4-1 fats may be used as long as they are acid-resistant.

〔Effect of the invention〕

As explained above, according to the present invention, heat-resistant and acid-resistant resin is filled between the edge seal portion of the ribbed electrode and the separator and the separator. A fuel cell with high safety and reliability can be provided by completely improving airtightness and preventing heat generation and characteristic deterioration due to mixing of fluid fuel and fluid oxidizer.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional perspective view showing an example of the structure of a fuel cell, FIG. 2 is a sectional view showing a conventional unit cell, and FIG. 3 is a sectional view showing an embodiment of the present invention. 1... Matrix, 2... Ribbed electrode, 3...
Separator, 4...fluorine resin.

Claims (1)

[Scope of Claims] (1) A pair of ribbed electrodes are arranged to sandwich a matrix impregnated with an electrolyte and have flow passages for a fluid fuel or a fluid oxidant, and each of the flow passages includes a pair of ribbed electrodes for disposing a matrix impregnated with an electrolyte. In a fuel cell constructed by layering several units of unit cells with a separator in between, which outputs electrical energy under conditions where an oxidizing agent is flowing, the ribbed electrode is A fuel cell □ characterized in that a lubricant having heat resistance and acid resistance □1 is filled between the end portion, the peripheral portion and the separator. □(2) A heat-resistant and acid-resistant (1) resin paint is applied on the surface of the peripheral part of the ribbed electrode, and □ unit cells are laminated (sl↑ is filled and filled with fat). The fuel cell described in paragraph (1).' (3) A film neck or sheet made of a heat-resistant and acid-resistant resin is attached to the base, sandwiched between the periphery of the electrode end and the separator, and heated and melted. A fuel cell according to claim (1), in which the cells are laminated and filled with resin. Range items (1) to (3)
A fuel cell according to any one of the following paragraphs.