JPH08190919A - Stacked phosphoric acid fuel cell - Google Patents

Abstract

PURPOSE: To suppress leak current between both electrodes of a unit cell, increase electric insulation, and enhance reliability. CONSTITUTION: A fuel electrode substrate 4 having fuel gas flowing grooves 4b and a fuel electrode 5 are accommodated in a recessed groove formed with a separator 1A made of a gas non-permeable carbon material, a separator edge part 2A, and a fluororesin gasket 3A. Similarly, an air electrode substrate 9 having air flowing grooves 9a and an air electrode 8 are accommodated in a recessed groove formed with a separator 1B, a separator edge part 2B, and a gasket 3B, and a matrix 6 retaining phosphoric acid is interposed between the fuel electrode 5 and the air electrode 8 to constitute a unit cell. In the unit cell, a fluororesin insulating sheet for holding the matrix 6 in a square hole in the central part is formed so that the outer edge is protruded outward on the side surface of the unit cell in which at least the fuel electrode 5 and the air electrode 8 are exposed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a structure in which a unit cell in which a matrix holding phosphoric acid is sandwiched between a fuel electrode and an air electrode is stacked, and fuel gas and air are supplied to generate a DC power by an electrochemical reaction. The present invention relates to the obtained laminated phosphoric acid fuel cell, and more particularly to the electric insulation structure of the single cell.

[0002]

2. Description of the Related Art FIG. 3 is a partially exploded perspective view showing a structure of a unit cell of a laminated phosphoric acid fuel cell which has been conventionally used. In this configuration, the fuel electrode has a rectangular fuel electrode substrate 4 having a plurality of fuel gas flow grooves 4a,
A separator 1A made of a gas-impermeable carbon material and a separator edge made of the same gas-impermeable carbon material, which is composed of a fuel electrode 5 having the same rectangular shape as that of the gas-impermeable carbon material. The fuel gas passage groove 4a is opened and stored in the concave groove formed by the portion 2A and the fluororesin packing 3A. Also, the air electrode
It is composed of a rectangular air electrode base material 9 having a plurality of air flow grooves 9a in a direction orthogonal to the fuel gas flow groove 4a, and an air electrode electrode 8 having the same rectangular shape, and is gas impermeable. Into a concave groove formed by a separator material 1B made of a carbon material and a separator edge portion 2B made of a carbon material which is also gas impermeable and a packing 3B made of a fluororesin, which are arranged at both end portions of one surface thereof. The air flow groove 9a is opened and stored. In the rectangular matrix 6 holding the phosphoric acid of the electrolyte, the width in the direction of the fuel gas flow groove 4a is the same as the width of the air electrode 8, and the width in the direction of the air flow groove 9a is the same as that of the fuel electrode 5. The insulating sheet 7 made of fluororesin has the same outer dimensions as those of the separators 1A and 1B, and has the same rectangular shape as the outer dimensions of the matrix 6 at the center thereof. The holes are formed. In this configuration, the separator 1A and the fuel electrode base material 4 are
The reservoir plate 10 disposed between and serves to supplement the phosphoric acid lost in the matrix 6 as the operation progresses.

FIG. 4 is a perspective view of a single cell formed by laminating the components shown in FIG. As shown in the figure, the outer periphery of the single cell is the separator 1 incorporating the separator edge portion 2A.
A, the insulating sheet 7, and the outer periphery of the separator 1B in which the separator edge portion 2B is incorporated, and the fuel electrode base material 4 and the fuel electrode 4 each having a fuel gas flow groove 4a on one of opposite side surfaces of the unit cell. The end face of the electrode 5 is exposed, and the end faces of the air electrode base material 9 having the air flow groove 9a and the air electrode 8 are exposed on the other side face that is orthogonal to the above side face. Further, the insulating sheet 7 made of fluororesin and the packings 3A and 3B keep air-tightness between the fuel gas flowing through both electrodes and the air. Further, the fuel electrode 5, the fuel electrode base material 4, the separator 1A and the separator edge portion 2A are electrically connected to each other, and the air electrode electrode 8, the air electrode base material 9, the separator 1B and the separator edge portion 2B are connected. Is electrically conductive, the electrical insulation between the two electrodes is maintained by the insulating sheet 7 made of fluororesin and the packings 3A and 3B.

Therefore, the unit cells constructed as described above are stacked to form a stacked phosphoric acid fuel cell, and the fuel gas is passed through the fuel gas passage groove 4a and the air is passed through the air passage groove 9a. Then, direct current power can be obtained by the electrochemical reaction.

[0005]

When a laminated phosphoric acid fuel cell is formed by using the single cell constructed as described above, it is possible to generate a predetermined amount of power, and therefore it is often adopted in various power generators. There is. However, even in the stacked phosphoric acid fuel cell having the unit cell configured as described above, the electric insulation performance between the electrodes of the unit cell may be deteriorated when the power generation operation is performed for a long time.

That is, the reaction gas discharged from the single cell may contain the reaction product water and the like in the form of water vapor, and may further contain the phosphoric acid mist generated from the phosphoric acid in the matrix 6. If it adheres to the side surface of the discharge side of the cell, the leakage current will increase. In the above structure, the electric insulation between the electrodes is held by the insulating sheet 7 and the packing 3B on the side where the fuel electrode is exposed, and by the insulating sheet 7 and the packing 3A on the side where the air electrode is exposed. However, all of these layers are extremely thin, only about 0.5 mm. Therefore, if the above-mentioned phosphoric acid mist adheres to this portion, there is a problem that the leakage current increases and the insulation performance is significantly reduced.

The present invention has been made in view of the above problems, and an object thereof is to suppress leakage current between both electrodes of a single cell and to provide highly reliable laminated phosphoric acid having excellent electric insulation. Type fuel cell.

[0008]

In order to achieve the above object, in the present invention, a rectangular matrix for holding phosphoric acid of an electrolyte is provided with a fuel electrode base material having a fuel gas flow groove and a fuel electrode. A unit cell formed by sandwiching between a rectangular fuel electrode composed of an electrode, an air electrode base material having an air communication groove in a direction orthogonal to the fuel gas communication groove, and a rectangular air electrode composed of an air electrode. In a laminated phosphoric acid fuel cell formed by alternately stacking rectangular separators, the separator has a fuel edge on one side and a fuel gas flow groove formed by the separator edge portion and packing arranged on the side edges. An insulating sheet having a concave groove for accommodating so as to open and a concave groove for accommodating the air electrode so that the air passage groove is open on the other surface, and the matrix having substantially the same thickness as the matrix. Installed in the center of In a rectangular hole formed into a rectangular shape, the insulating sheets are laminated at least in the portion where the fuel electrode is exposed on the side surface of the single cell and the air electrode is exposed in the side surface of the single cell. It should be formed so as to project outward from the side surface of.

Further, the insulating sheet is made of fluororesin. Furthermore, the above packing is made of fluororesin.

[0010]

As described above, in the laminated phosphoric acid fuel cell, at least the fuel electrode and the air electrode are provided with an insulating sheet made of, for example, a fluororesin for accommodating the matrix in the rectangular hole provided in the central portion. In the portion exposed on the side surface of the cell, if it is formed so as to project outward from the side surface of the stacked separator, between the exposed fuel electrode and the separator edge portion of the air electrode, and the exposed air electrode. The separator edge portion of the fuel electrode is separated by an insulating sheet made of, for example, fluororesin and a packing made of, for example, fluororesin, which protrudes outward, so that the insulation distance between the two electrodes becomes the same as the conventional configuration. It will be significantly longer than that. Therefore, even if the phosphoric acid mist contained in the reaction gas discharged from the single cell adheres to this portion, the ratio of adhering to the electrodes in communication with each other is significantly reduced, and even if they adhere to each other in communication. Since the distance is long, the leakage current is greatly reduced, and the insulation performance is greatly improved.

[0011]

EXAMPLE FIG. 1 is a perspective view showing a partially exploded structure of a unit cell of an example of a stacked phosphoric acid fuel cell according to the present invention. Among the components of the unit cell of the embodiment shown in this figure, the components having the same functions as the components of the unit cell of the conventional example shown in FIG. 3 are assigned the same reference numerals and overlapping description will be omitted. . The difference between this embodiment and the conventional example is that the matrix electrode 6 is arranged between the fuel electrode 5 and the air electrode 8.
Has a shape of an insulating sheet 7A made of fluororesin which is housed in a square hole provided in the central portion. The outer edge of the insulating sheet 7 of the conventional example shown in FIG. 3 has separators 1A and 1B. While it was formed to have the same shape as the outer edge,
The insulating sheet 7A of the embodiment shown in the figure has an outer side surface of the stacked separators at least at a portion where the fuel electrode is exposed on the side surface of the single cell and an air electrode is exposed on the side surface of the single cell. The feature is that it is formed so as to project in one direction.

FIG. 2 is a perspective view of a single cell formed by laminating the components of the embodiment shown in FIG. Since the insulating sheet 7A made of the fluororesin formed as described above is used, the insulating sheet 7A partially projects on each side surface of the single cell. Insulation sheets 7A are formed on both ends of each side so as to have the same outer edges as the separators 1A, 1B, separator edge portions 2A, 2B, and packings 3A, 3B made of fluororesin without protruding. When the manifolds (not shown) for supplying or discharging the fuel gas and the air are incorporated on the respective side surfaces after stacking the unit cells, the both ends serve as the connecting surfaces.

In this structure, for example, the fuel electrode substrate 4
Even if the fuel gas discharged from the fuel gas flow groove 4a contains a phosphoric acid mist, the phosphoric acid mist adheres to the insulating sheet 7A made of fluororesin protruding outward. Even if the separator edge portion 2B which is electrically connected to the air electrode and the fuel electrode 5 may be communicated with each other by the phosphoric acid mist, the distance is significantly longer than the conventional one, and the leakage current is reduced. It will be suppressed to a minute current. Even if the air discharged from the air flow groove 9a of the air electrode base material 9 contains phosphoric acid mist, the separator edge portion 2A and the air electrode 8 may be communicated by the phosphoric acid mist. Similarly to the above, the leakage current is suppressed to a minute current. Therefore, by adopting this configuration, a laminated phosphoric acid fuel cell with high insulation performance reliability is obtained.

[0014]

As described above, according to the present invention, the rectangular matrix holding the phosphoric acid of the electrolyte is formed into the rectangular fuel consisting of the fuel electrode base material having the fuel gas flow channel and the fuel electrode. A single cell sandwiched between a pole and a square air electrode consisting of an air electrode base material and an air electrode electrode having an air flow groove in a direction orthogonal to the fuel gas flow groove alternates with a square separator. In a stacked phosphoric acid fuel cell formed by stacking the fuel cell with a separator, the separator edge portion arranged on the side edge of the separator and the packing made of, for example, a fluororesin form a fuel gas flow groove on one side of the fuel electrode. To form a concave groove for accommodating the air electrode so that the air passage groove is opened on the other surface, and the matrix has an approximately same thickness as the matrix. Provided in the center In the case of being housed in a rectangular hole, the insulating sheet is formed of, for example, fluorocarbon resin, and at least the portion where the fuel electrode is exposed on the side surface of the unit cell and the air electrode is exposed on the side surface of the unit cell. Since it is formed so as to project outward from the side surface of the stacked separator, even if the exhaust gas of the reaction gas of the single cell contains phosphoric acid mist, even if attached to the insulating sheet, It has become possible to obtain a highly reliable laminated phosphoric acid fuel cell having excellent electrical insulation and capable of suppressing leakage current between both electrodes of a single cell.

[Brief description of drawings]

FIG. 1 is a partially exploded perspective view showing the structure of a unit cell of an embodiment of a laminated phosphoric acid fuel cell of the present invention.

FIG. 2 is a perspective view of a single cell formed by stacking the components of the embodiment shown in FIG.

FIG. 3 is a partially exploded perspective view showing the structure of a single cell of a conventional stacked phosphoric acid fuel cell.

FIG. 4 is a perspective view of a single cell formed by stacking the conventional components shown in FIG.

[Explanation of symbols]

 1A, 1B Separator 2A, 2B Separator edge part 3A, 3B Packing 4 Fuel electrode base material 4a Fuel gas flow groove 5 Fuel electrode electrode 6 Matrix 7 Insulation sheet 7A Insulation sheet 8 Air electrode electrode 9 Air electrode base material 9a Air flow Groove 10 Reservoir plate

Claims (3)

[Claims] 1. A rectangular matrix for holding phosphoric acid of an electrolyte, a rectangular fuel electrode composed of a fuel electrode substrate having a fuel gas flow groove and a fuel electrode, and a fuel gas flow groove orthogonal to the rectangular fuel electrode. Laminated phosphoric acid formed by alternately laminating a unit cell formed by sandwiching an air electrode base material having an air flow groove in a direction and a rectangular air electrode consisting of an air electrode, and a rectangular separator. Type fuel cell, the separator has a concave groove for accommodating the fuel electrode so that the fuel gas flow groove is opened on one surface by a separator edge portion arranged on the side edge and packing, and another surface. A groove having a concave shape for accommodating the air electrode so that the air flow groove is opened, and the matrix is provided in the center of an insulating sheet having substantially the same thickness as the matrix. Also stored in the hole In the insulating sheet, at least at a portion where the fuel electrode is exposed to the side surface of the unit cell and at a portion where the air electrode is exposed to the side surface of the unit cell, outside the side surface of the stacked separator. A laminated phosphoric acid fuel cell, which is formed so as to project. 2. The laminated phosphoric acid fuel cell according to claim 1, wherein the insulating sheet is made of a fluororesin. 3. The stacked phosphoric acid fuel cell according to claim 1, wherein the packing is made of a fluororesin.