JPS58103784A - Fuel cell - Google Patents

Abstract

PURPOSE:To readily supply an electrolyte to a matrix from the outside of a battery and provide a cell having stable performance and long life by passing through a path connecting a separator, a fuel electrode, a matrix, and an oxidizing agent electrode with an electrolyte reservoir installed in the edge of the separator by an electrolyte supply groove installed in the separator. CONSTITUTION:When an electrolyte is supplied, an electrolyte is filled in an electrolyte path 9 and overflowed in an electrolyte reservoir 8 of each cell. The electrolyte overflowed in the electrolyte reservoir 8 enters an electrolyte supply groove 6 and is supplied to a matrix 1 through an electrolyte connecting path 10. To prevent wetting of a fuel electrode base material 2a by the electrolyte, the fuel electrode base material 2a is coated with polytetrafluoroethylene to make it water repellent. When the electrolyte is supplied to the fuel electrode base material 2a by electrolyte supply pressure, the number of the stacked cells which are an electrolyte supply unit are decreased to reduce electrolyte supply pressure. After the electrolyte is filled in electrolyte supply groove 6, the electrolyte is removed from the electrolyte path 9 to prevent liquid short circuit by the electrolyte.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fuel cells, and in particular to fuel cells for electric power.

Fuel cells, which produce fuel and oxidant gas energy, are a long-known technology.

A fuel cell consists of a fuel electrode, an oxidizer electrode attached to the fuel electrode,
an electrolyte placed between these electrodes and in contact with them;
The basic configuration includes a separator that also serves as a current collector plate, a fuel electrode, and a gas flow path for fuel gas and oxidant gas formed between the oxidizer electrode and the separator. The electrolyte can then be a solid, a molten paste, a free flowing liquid, or a liquid held within a matrix. this house,
Fuel cells using matrix-supported electrolytes are suitable for many applications.

However, in order for a fuel cell using an aqueous electrolyte held within such a matrix to operate under optimal conditions, the matrix must have certain properties. For example, the matrix is hydrophilic and
The matrix must be continuous and free of pinholes or cracks to prevent cross-crossing and mixing of gases within the fuel cell, and the matrix is typically formed to a thickness of 1 mm or less, but it is important to minimize internal resistance. In order to reduce the size, it is necessary to make the matrix as thin as possible, and the matrix must be in close contact with the catalyst layer. Furthermore, in order to make the current distribution uniform, it is desirable that the matrix thickness be uniform and the pore size of the matrix be uniform, and the matrix material must be thermally and chemically stable and economical. Must be. If a matrix having such properties is impregnated with an electrolyte and combined with electrodes to assemble a battery, stable performance can be expected over a long period of time.

However, the matrix and electrodes are porous, and fuel gas and oxidant gas are constantly flowing through the electrode matrix.
During long-term operation, there was a problem in which the electrolyte was lost through evaporation and the battery performance deteriorated.

In order to eliminate this problem, we have proposed a method in which the matrix is impregnated with electrolyte from the gas path of the separator through holes drilled in the electrode base material, and a method in which the cell is made vertical and an electrolyte passage and an upper electrolyte section are provided at the top of the cell. A method has been proposed in which a matrix is impregnated with an electrolyte through a method. but,
The former method has the drawback that the electrolyte adheres to the electrode base material during electrolyte impregnation, impeding gas diffusion and reducing battery output, while the latter method impregnates the electrolyte part provided at the top of the battery. Therefore, in the case of large electrodes, there is a drawback that the impregnation time is long.

The present invention aims to eliminate these problems and provide a fuel cell that can easily supply an electrolyte to the cell matrix outside the cell, has stable performance and a long life, and has a fuel electrode and an oxidizer. A unit cell consisting of a matrix that holds an electrolyte between a pair of electrodes is stacked with a separator having a wave path for supplying fuel gas and oxidant gas to the pair of electrodes. In a fuel cell, a ridge supply groove is provided on at least one of the fuel electrode side and the oxidizer electrode side of one separator, and this electrolyte supply groove and the matrix are communicated through an electrolyte communication hole located in the electrode. The first feature is that a water-repellent layer is provided on the electrolyte communication hole and the water-repellent layer on the electrolyte communication hole, and furthermore, the above-mentioned , Matrix, RFL agent Imi and Separate gold J! ! The second feature is that the 'am reservoir V provided in the separator is connected through the iW*iWi path provided through the separator.

The present invention provides an electrolyte supply groove in the separator to communicate the P1 separator, the fuel cell, the matrix, and the oxidizer electrode, and a passage provided at the edge of the separator to communicate the electrolyte electrolyte. By making it possible to supply electrolyte from the electrolyte to the IJ Lux via the supply groove, it absorbs changes in the electrolyte in the matrix due to moisture absorption and evaporation, and always maintains a constant electrolyte in the matrix. This is what made it possible.

Examples will be described below.

1 to 3 show the structure of a fuel cell according to one embodiment, and the same parts are given the same reference numerals.

This embodiment relates to a phosphoric acid fuel cell using a hydrogen-rich gas as a fuel, oxygen in the air as an oxidizing agent, and a phosphoric acid type electrolyte. FIG. 1 is a partial sectional view, and FIGS. 2 and 3 are respectively Plan views of different wall sections are shown. In this diagram, 1
The matrix is a mixture of silicon carbide and polytetrafluoroethylene, or phenol resin cloth. 2 is fuel electrode purchasing material 2a and fuel catalyst pigeon 2
3 is an oxidizer electrode consisting of an oxidizer electrode base material 3a and a modifier catalyst + 173b. A required number i*1- of unit cells consisting of the matrix 1, the fuel electrode 2, and the oxidizer electrode 3 are formed through the separator 4.

The separator 4 has a fuel supply gas passage 5 and an electrolyte supply groove 6 on the fuel electrode 2 side, and an oxidizer supply gas passage 7 and 'I!' on the oxidizer electrode 3 side. A laminate reservoir 8 is provided, and the electrolyte mass 8 and the electrolyte supply groove 6 have a structure in which the 'lf opening communicates with each other. Reference numeral 9 denotes an electrolyte passage provided at the edge of the seed layer's pond, which passes through the stacked batteries through iX, and serves as a passage for supplying electrolyte to each battery after the batteries are stacked. 10 is #IL between the electrolyte supply groove 6 provided in the separator 4 and the matrix 1; the electrolyte communication hole 11 provided in the fuel electrode 2 is a seal for communicating the electrolyte.

In a fuel cell having such a structure, when an electrolyte is supplied, the electrolyte passage 9 is filled with the electrolyte, and the electrolyte reservoir 8 of each cell is overflowed, so that the electrolyte mass 8 is filled with the electrolyte. The electrolyte filling the electrolyte reservoir 8 is used for electrolyte supply @6
The electrolyte is then supplied to the matrix 1 through the electrolyte communication hole 10. In this case, in order to prevent the electrolyte from wetting the fuel electrode base material 2a, the fuel electrode base material 2a may be made water repellent by applying, for example, polytetrafluoroethylene.

Furthermore, when electrolyte enters the fuel electrode base material 2a due to electrolyte replenishment pressure, the electrolyte replenishment pressure may be lowered by reducing the number of stacked cells forming an electrolyte replenishment unit. After filling the electrolyte supply groove 6 with electrolyte, the electrolyte is removed from the electrolyte jJ7i passage 9 to prevent a liquid short circuit caused by the electrolyte.
Electrolyte (9) is also removed from electrolyte mass 8, but this does not affect performance.

In the fuel cell configured as described above, when the amount of electrolyte in the IJ sock increases due to moisture absorption, the surplus overflows into the electrolyte supply groove 6 through the electrolyte communication hole 10, and It overflows into the water tank 8 and is stored in the turtle water tank 8. In addition, when the electrolyte in the matrix 1 is insufficient due to evaporation, the insufficient amount is removed from the electrolyte communicating hole 10.
The electrolyte is supplied through the electrolyte supply groove 6. Therefore, the amount of electrolyte in the matrix 1 is always kept at a certain level, which stabilizes the battery performance and stores excess electrolyte jx during moisture absorption. 3b will not be excessively wetted, and the electrode performance will be stabilized. Furthermore, when the electrolyte in the electrolyte supply groove 6 decreases, it is sufficient to replenish the electrolyte through the entire electrolyte passage 9, thereby eliminating deterioration in battery performance due to lack of electrolyte. Furthermore, the position of the electrolyte communication hole 10 can be determined according to the electrolyte suction ability of the matrix 1.
Penetration of the electrolyte into the matrix can occur at a sufficient rate (10). In addition, 11f electrolyte supply #6 is provided to limit the electrolyte supply path in the separator 4, so the electrode base material will not be wetted by the electrolyte supply path and gas diffusion will not be hindered. effective.

FIG. 4 shows a cross section of another embodiment, in which the electrolyte reservoir 8, the electrolyte supply groove 'a and the electrolyte communication hole 10 are filled with fibers 12. is different from the embodiment shown in FIG. The fibers 12 have the effect of improving the rate of impregnation of the solute by their capillary force and making the distribution of % solute uniform.

The fibers 12 used here include silicon carbide fibers, carbon fibers, glass fibers, phenol resin fibers, and the like. Also, instead of fibers, other hydrophilic materials such as silicon carbide powder, carbon powder can be used as a binder, such as bo-IJ f-Drafluoroethylene,
It is also possible to use one bound with polyimide, and the same effect can be obtained. Additionally, for example, carbon sheets.

A porous sheet such as a silicon carbide sintered body (11
) may be used. Further, the same material as the matrix material may be used, but in this case, the matrix 1, electrolyte connection 1 PU hole 10,'! 1f, platelet feeding groove 6
, and between the small pores of the material used in the phlegm reservoir 8, the pores of the material used in the matrix 1 are minimized, and the violet through hole 10, the electrolyte supply groove 6, and the phlegm reservoir 8 are arranged. It is desirable that the relationship increases in the order of 8. In other words, by doing this, if a difference is made in the capillary force, then due to this difference in capillary force, 1!
The solution mass will be kept more multistable. Further, the electrolyte mass 8 and the fibers 12 of the ``capillary supply groove 6'' can be omitted if the capillary force is within the above-mentioned range.

FIG. 5 shows a cross section of another embodiment, and the difference between this embodiment and that of FIG. 1 is that the electrolyte passage 9
(9a, 9b) and the cage 8 are provided at both edges of the battery. With this configuration, it is possible to increase the replenishment rate of electrolyte, and at the time of initial filling, the electrolyte is supplied from one electrolyte passage 9a, and the electrolyte is supplied from the other electrolyte passage 9b. By allowing it to overflow, filling of the electrolyte can be ensured.

In the embodiments shown in FIGS. 1 to 5 above, 'i' is attached to the fuel electrode.
[Although the case where the solute supply groove is provided has been described, it may be provided at the oxidizer electrode, or may be provided at both the fuel electrode and the oxidizer electrode.

As described above, the present invention makes it possible to easily supply an electrolyte to the matrix from outside the cell, and to provide a fuel cell with stable performance and long life, and has great industrial effects. It is.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an embodiment of the fuel cell of the present invention, FIGS. 2 and 3 are plan views of different main parts from FIG. 1, and FIGS. 4 and 5 are respectively FIG. 7 is a sectional view of a main part of another different embodiment. DESCRIPTION OF SYMBOLS 1... Matrix, 2... Fuel electrode, 3... Oxidizer electrode, 4... Separator, 5... Gas path for fuel supply, 6... Groove for electrolyte supply, 7... Oxidizing agent supply gas path, end...electrolyte section, 9...electrolyte passage, 10.10
a, IQb 1 figure

Claims (1)

[Claims] 1゜A unit cell configured by disposing a matrix that holds an electrolyte between a pair of electrodes, a fuel electrode and an oxidizer electrode,
In a fuel cell formed by stacking layers with separators interposing flow paths for supplying fuel gas and oxidant gas to the pair of electrodes, at least one of the fuel electrode side and the oxidizer electrode side of the separator is provided with an electrolyte for supplying an electrolyte. a groove is provided, the electrolyte supply groove and the matrix are communicated through an electrolyte communication hole located in the electrode, and an imitation aqueous layer is provided on a surface of the electrolyte communication hole and the electrolyte supply groove that faces the electrode. A fuel cell characterized by: 2. The inside of the 'fItL rigid supply groove brocade is filled with hydrophilic fibers, a mixture of hydrophilic powder and a binder, a porous sheet, and a matrix material.
The fuel pond as described in item 1 of the scope of liver choquing. 3. The fuel cell according to claim 1 or 2, wherein the electrolyte communication hole is filled with a hydrophilic filler and a matrix material. 4. The fuel cell according to claim 1 or 2, wherein the electrolyte communication hole is filled with a mixture of a hydrophilic material powder and a binder. 5. A unit cell configured by disposing a matrix that holds an electrolyte between a pair of electrodes, a fuel electrode and an oxidant electrode, has a flow path for supplying fuel gas and oxidant gas to the pair of electrodes. In a fuel cell stacked with a separator in between, an electrolyte supply groove is provided on at least one of the fuel electrode side and the oxidizer electrode side of the separator, and the electrolyte supply groove and the IJ rack are located within the electrode. The oxidizer electrode and the separator are connected to each other through an electrolyte communication hole, and the electrolyte communication hole is connected to the fuel electrode, the oxidizer electrode, and the separator through an electrolyte passage provided in communication with the oxidizer electrode and the separator. It communicates with the tago solute reservoir,
A fuel cell characterized in that a surface of the electrolyte communication hole and the electrolyte supply groove facing the electrode is provided with water repellency. 6. Claim 5, wherein the electrolyte supply groove is filled with any one of hydrophilic fibers, a mixture of hydrophilic powder and a binder, a porous sheet, and a matrix material. Fuel cell as described in Section. 7. The fuel pond according to claim 5 or 6, wherein the electrolyte communication hole is filled with either a hydrophilic material or a matrix material. 8. The fuel cell according to claim 5 or 6, wherein the electrolyte communication hole is filled with a mixture of a hydrophilic material powder and a binder. 9. Claims 5 to 8, wherein the electrolyte portion is filled with any one of a hydrophilic fiber, a mixture of hydrophilic powder and a binder, a porous sheet, and a matrix material. The fuel cell described in any one of the preceding paragraphs. 10. The electrolyte holding power of the matrix, the electrolyte communication hole, the electrolyte supply groove, and the electrolyte part is the largest in the matrix, and decreases in the order of the electrolyte communication hole, the electrolyte supply groove, and the electrolyte part. A fuel cell according to one item having a fall within the range from item 5 to item 9.