JPH01137565A - Fuel cell - Google Patents

Abstract

PURPOSE:To allow the operation for a long time without frequently supplying an electrolyte from the outside by communicating a reservoir section to the first layer or the third layer and supplying the electrolyte stored in the reservoir section to the first layer or the third layer. CONSTITUTION:An electrolyte stored in the reservoir section 23 of the seal section 22 of a gas separation plate 11 is moved to the third layer 17 through a communicating hole 24, infiltrated to portions of the third layer 17 where little amount of electrolyte exists or the concentration of the electrolyte is small, and moved to electrodes 2 and 3 and a matrix 1 through the rib section 19 of the third layer 17. When the electrolyte stored in the reservoir section 23 of the seal section 22 is consumed and exhausted by this shift, the plug 26 of a through hole 25 is removed, the electrolyte is poured from the outside through the through hole 25 and stored in the reservoir section 23. The electrolyte can be stored and supplied in the reservoir section 23 of the seal section 22 even during the operation for a long time on the level of tens of thousands hr, and the electrolyte can be invariably supplied to the third layer through the communicating hole 24. A fuel cell can be stably operated for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a gas separation plate for a stacked fuel cell.

[Conventional technology]

FIG. 4 is a cross-sectional view showing the most typical cell structure of a conventional fuel cell disclosed in, for example, Japanese Patent Publication No. 58-152. In the figure, (1) is a matrix that holds an electrolyte, (2) and (3) are electrodes, and catalysts containing electrolytes are placed in porous electrode base materials (4) and (5) made of carbon fiber, etc. The layers (6) (7) are provided, and the ends are provided with a wet gas seal +81 (91).

A gas separation plate (also called a separator or interconnector) is made of an air-impermeable plate, such as dense carbon.
Grooves (13Q11) perpendicular to each other are formed on both sides of the grooves, which serve as flow paths for fuel gas and oxidant gas.In general, the matrix (IJ and electrodes (2+
A fuel cell is constructed by alternately stacking a combination of (3) (hereinafter referred to as a unit power generation element) and gas separation plates αG.

Next, the operation will be explained. A fuel gas and an oxidizing gas are respectively supplied to mutually orthogonal grooves Q3 (g) of the gas separation plate αQ. These gases are applied to the electrode base material (41(5)
catalyst layer (6) (7
1, reacts through the matrix (1), and generates electricity.

Here, surplus gas not used in the reaction and water vapor gas which is a reaction product are exhausted to the outside through the groove cla (g), but this exhaust gas contains a matrix (υ
The electrolyte contained in the electrode (21(3)) exists in the form of vapor determined by the operating conditions of the fuel cell, and the electrolyte is also discharged to the outside. There are parts where there are many reactions and parts where there are few reactions, and in the parts where there is a lot of reaction, there is a lot of water vapor gas and surplus gas which are reaction products, and a lot of electrolyte is also discharged to the outside along with these. The amount of electrolyte in the matrix (1) decreases little by little, and eventually there is no longer enough electrolyte in the matrix (1) for the reaction, and no output is produced.In order to solve this problem, the applicant filed a patent application filed in 1983. No. 168725 discloses that a part of the gas separation plate is made porous, and excess electrolyte not directly involved in the reaction is stored in this porous part.

Note that a wet gas seal +81 (91) prevents fuel gas and oxidant gas from leaking to the outside from the porous electrode base material (41 (5)).

[Problem that the invention seeks to solve]

Conventional fuel cells are constructed as described above, so only the matrix (1) and electrodes (21 (30) are retained, and when operated for a long period of time, the electrolyte is lost due to evaporation, scattering, etc.) There was a shortage of electrolyte, and it was necessary to frequently replenish the electrolyte.Also, in Japanese Patent Application No. 168725/1989, which was filed to solve this problem, excess electrolyte stored in the porous part of the gas separation plate was (If this happens, there is no means for replenishing the electrolyte into this porous portion, so there is a problem in that it is necessary to replenish the electrolyte as frequently as in the case where the gas separation plate does not have a porous portion.

This invention was made to solve the above-mentioned problems, and its object is to provide a fuel cell that can constantly replenish electrolyte to a porous portion provided in a gas separation plate.

[Means for solving problems]

The fuel cell according to the present invention includes a unit power generation element composed of a matrix holding an electrolyte and a pair of electrodes sandwiching the matrix, a porous first layer having a plurality of grooves on one surface,
An impermeable zlil whose one surface is in contact with the other surface of this first layer, and one surface which is in contact with the other surface of this second layer and the other surface of the first layer is in contact with the other surface of the second layer. a porous third layer having a plurality of grooves orthogonal to the groove; and an air impermeable layer provided along the groove direction at the ends of the third layer and the first layer and integrated with the second layer. a gas separation plate which is stacked alternately with the unit power generating element; a storage part in which the electrolyte is stored is provided in the seal part; and the storage part is placed in the first layer or the third layer. It is a communication.

[Effect]

The reservoir in this invention communicates with the first [or third layer] so that the electrolyte stored in the reservoir can be transferred to the first layer.
Always replenish wJ or 3rd layer.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
1 is an exploded perspective view showing the cell structure of a fuel cell according to an embodiment of the present invention, and FIG. 2 is a partial perspective view showing a part of the gas separation plate of FIG. 1. In Figures 1 and 2, (
1) to (3) are the same as the above conventional ones,
Constitutes a unit power generation element. This is a gas separation plate that is alternately stacked with unit power generation elements on both sides. In the gas separation plate (6), a plurality of sprues are formed on one surface by the rib portion Q4 and the web portion side, and the porous first layer aS is bonded to the other surface of this No. 111, that is, the web portion side. The integrated air-impermeable second layer has grooves (7) on one side formed by rib bends and web portions (4) and a porous third layer.
The other surface is adhesively integrated with the second layer the, with the groove (7) perpendicular to ma3 of the first layer (6).

Yu is an air-impermeable seal part that is provided along the groove direction at both ends of the first layer @ and is adhesively integrated with the second layer QO. The second layer O
The air-impermeable sealing part that is integrated with Q is a reservoir formed in the shape of a groove whose end is sealed in the sealing part, and there is a communication hole that communicates with the third mση and a sealed part. A through hole (7) is provided through the end. (to) is a plug that closes the through hole (to).

The gas separation plate port configured as described above is also called a composite ribbed separator, and is stacked alternately with unit power generating elements to constitute a fuel cell.
The electrolyte is stored in the third layer ση, and the electrolyte is stored in the storage portion (to).

Next, the operation will be explained. Fuel gas and oxidizing gas are supplied to the grooves □□□ and (7) formed in the first layer side and the third layer aη of the gas separation plate συ, respectively.

At this time, the second layer of the gas separation plate port prevents the fuel gas and oxidizing gas flowing through these grooves aaaa from mixing with each other, and both gases reach the electrode (21(3)), are ionized, and form a matrix. The reaction occurs through (1) and generates electricity. Here, surplus gas that is not used in the reaction and water vapor gas that is a reaction product are exhausted to the outside through groove 03 (g). contains the electrolyte contained in the matrix (1) and the electrode +21 (31) as vapor, and the electrolyte is discharged to the outside.
The electrolyte in the upper part becomes insufficient, but the first layer (
b) and the electrolyte stored on the third layer side is
3 and the web portion C15Gl) on the third layer side and freely move within the first layer side and the third layer 0, and the rib portion σ4Q
1 to make up for the shortage and move to matrix (1) and electrode (2) (31).

Figure 3 shows the relationship between the amount of phosphoric acid evaporated and the operating time when the electrolyte is phosphoric acid at operating temperatures of 205°C and 220°C. , it becomes a measure to overcome the storage wind inside the electrolyte cell. Moreover, as the operating temperature increases, the amount of electrolyte evaporation also increases. Therefore, in order to operate at high temperatures for as long as possible, it is necessary to increase the amount of electrolyte stored inside the gas separation plate (b) and to replenish the electrolyte from the outside.

The electrolyte stored in the storage part Q of the seal part (support) of the gas separation plate αD moves to the third layer side through the nine consecutive holes (b), and the electrolyte of the 31st a force is small. Alternatively, as the electrolyte penetrates into a place where the concentration is small, the rib of the third m1lI force I' Ql 8 i11+ is electric% tz+ (3
) and move to matrix (1). When the electrolyte stored in the storage part (to) of the seal part (part) is no longer consumed by this movement, the plug (to) of the through-hole (a) is removed and the through-hole (c) is inserted from the outside. inject electrolytes,
Electrolyte is stored in the storage part (a). In this way, even during long-term operation, electrolyte can be stored and replenished in the storage section of the seal section, and the third layer can be constantly replenished through the communication hole. Can operate stably.

Above, we have explained the function of replenishing the shortage due to electrolyte evaporation, scattering, etc., but especially when the electrolyte is phosphoric acid, it is necessary to change the starting/stopping or operating conditions (operating pressure).

The volume of the electrolyte changes (expands and contracts) depending on the operating temperature, gas utilization rate, position within the cell plane, etc., and a function to absorb this volume change of the electrolyte is also required. Gas separation plate συ
The first layer (6) and the third layer αη store the electrolyte, but they are in a state where they leave voids, and during operation, the electrolyte matrix tl+ and the electrode (2+ (31
Inflated r! iSolytes can be absorbed, and in the case of electrolyte contraction, the electrolyte returns to the necessary part as in the case of a shortage.

In addition, in the above embodiment, a case was explained in which the seal part gloss was not inserted into the reservoir opening.
〇If a porous body with a pore diameter equal to or larger than the pore diameter of the pores is inserted into the reservoir mouth to fill the space, the electrolyte will be distributed more uniformly in the longitudinal direction of the reservoir Q.
The electrolyte does not move to the 3rd layer α force more than necessary, and the 31st layer α
Only the amount of electrolyte lacking in η can be replenished from the reservoir.

Also, in the above embodiment, the case where the reservoir is provided only at the mouth of the seal is explained, but the reservoir may be provided only in the seal, or in both the mouth of the seal. , if it communicates with the first layer side or the third dove U, the same effect as in the above embodiment can be achieved.

〔Effect of the invention〕

As described above, according to the present invention, a fuel cell includes a unit power generating element constituted by a matrix holding an electrolyte and a pair of electrodes sandwiching the matrix; one layer, an air-impermeable second layer with one surface in contact with the other surface of this first layer, and one surface in contact with the other surface of this second layer and the other surface in contact with the other surface of the second layer. a porous third layer having a plurality of grooves perpendicular to the #1 groove; and a porous third layer provided along the groove direction opposite the third layer and the 17th layer and integrated with the second cliff. a gas separation plate formed with a sealed air-impermeable seal part and stacked alternately with the unit power generating element; a storage part in which the electrolyte is stored in the seal part;
Since this reservoir is configured to communicate with the first layer or the third M, electrolyte can be constantly replenished from the reservoir to the first or third layer, so there is no need to frequently replenish electrolytes from the outside, and it can be used for a long period of time. This has the effect of providing a fuel cell that can be operated.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing the basic configuration of a fuel cell according to an embodiment of the present invention, FIG. 2 is a partial perspective view showing a part of the gas separation plate in FIG. 1, and FIG. 3 is an evaporation amount of phosphoric acid. FIG. 4 is a sectional view showing the basic configuration of a conventional fuel cell. In the equation, (1) is a matrix, (2) and (3
) is the electrode, (6) is the gas separation plate, 4 is the first layer of gas separation temporary fixing, light is the second layer of gas separation plate 0, aη is the gas separation plate α
The third HJ, @ and the opening of D are the sealing part of the gas separation plate αυ, and the opening is the storage part. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (4)

[Claims] (1) A unit power generation element composed of a matrix that holds an electrolyte and a pair of electrodes sandwiching the matrix; a porous first layer with a plurality of grooves on one surface; an air-impermeable second layer having one side abutted against the surface;
One surface is in contact with the other surface of the layer, and the other surface is in contact with the first layer.
a porous third layer having a plurality of grooves orthogonal to the grooves of the layer; and a porous third layer provided along the groove direction at both ends of the third layer and the first layer and integrated with the second layer. an air-permeable sealing section, and a gas separation plate that is stacked alternately with the unit power generation elements;
A fuel cell having a reservoir communicating with a layer and storing an electrolyte. (2) The fuel cell according to claim 1, wherein the reservoir is a groove whose end is sealed. (3) The fuel cell according to claim 2, wherein the groove has a through hole at a sealed end. (4) The fuel cell according to any one of claims 1 to 3, wherein a porous body is inserted into the reservoir.