JPS60198059A - Electrolyte supply structure of matrix type fuel cell - Google Patents

Abstract

PURPOSE:To prevent liquid junction by arranging a hydrophilic material which faces a hole of liquid receiver and to which a hole of liquid receiver located in the direct upper part is vertically projected in each liquid receiver when the liquid receiver having a hole is installed in an electrolyte supply path and electrolyte is dropped to the lower liquid receiver. CONSTITUTION:Electrolyte is supplied from an electrolyte supply path 7 to a unit cell comprising a matrix 1, an oxidizing agent electrode 3, and an electrode substrate with rib 4 through a hydrophilic material 9. The electrolyte is supplied to the lower unit cell through holes 71a and 72a of plates 71 and 72 which serve as liquid receiver installed in the path 7. The hole 71a is arranged zigzag with the hole 72a. A hydrophilic material 9a which faces the hole 72a and to which at least a part of a hole 71b located in the direct upper part is projected is arranged in each liquid receiver. Therefore, since liquid dropped is spreaded without forming liquid drop, forming of liquid junction is prevented.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention provides a plurality of liquid receivers each having a hole in an electrolyte replenishment passage arranged vertically, and the electrolyte is supplied to the liquid receiver below the hole. The present invention relates to an electrolyte replenishment structure for a matrix fuel cell in which the electrolyte dripped and retained in the liquid receiver is replenished to the matrix via an electrolyte replenishment path communicating with the matrix.

[Prior art and its problems]

As an electrolyte replenishment structure for matrix-type fuel cells that replenishes electrolyte to a matrix supporting electrolyte, stain solute is dripped through a vertical replenishment passage provided in a cell stack made up of a number of stacked unit bodies such as unit cells. Structures that replenish electrolytes to the matrix are known. A conventional electrolyte replenishment structure will be described below based on the drawings.

FIG. 1 is an exploded perspective view showing an example of a unit cell of a matrix type fuel cell. As shown in FIG. A porous lip-attached electrode base material 4 having grooves 4a provided on the outside in the direction of arrow A, and a porous lip-attached electrode base material 5 having grooves 5a provided in a direction orthogonal to the grooves 4a. It is provided. Electrode base material with lip 4
, 5 are in close contact with the fuel electrode 2 and the oxidizer electrode 3, respectively, to form a unit cell together with the matrix 1. A separator plate 6 is interposed between the unit cells to separate the reaction gas, and a large number of these are stacked. constitute a cell stack. The fuel gas as a reactive gas is directed in the direction of arrow A, and the oxidant gas is directed in the direction of arrow B, respectively, with ribbed electrode base materials 4 and 5.
The electric current flows through the grooves 4a and 5a, and causes an electrochemical reaction in the unit battery to generate electricity.

In such a configuration, the electrolyte held in the matrix evaporates and scatters before the start of operation or as the operation continues, so it is necessary to replenish the electrolyte even during operation. As shown in FIG. 2, as a replenishment structure for this reservoir, electrolyte replenishment passages 7, 7a are vertically provided in the cell stack constituting the fuel cell, and replenishment passages 7, 7a are provided in the ribbed electrode base material 4 on the fuel electrode side. It has been proposed to provide an electrolyte replenishment path 8 connected to the electrolyte replenishment path and to replenish electrolyte via this replenishment path.

FIG. 3 is a partial cross-sectional view of a cell stack formed by stacking unit cells made of electrode base materials with lips and the like having the electrolyte replenishment passages 8 and 8. In FIG. The electrolyte supply channel 8 is provided facing the matrix l, and the electrolyte supply channel 8 is filled with a hydrophilic material 9.

A plate 71 as a liquid receiver is attached to the electrolyte supply passage 7 at the same level as the surface of the matrix l, and a drip hole '71a is provided. In order to replenish the matrix of unit cells in the lower stage, a plate 72 as a liquid receiver is provided in the same manner as '21, and drip holes 72a are provided, and the drip holes are sequentially provided in this manner. As shown in FIG. 4, which is a partial plan view of the electrolyte replenishment structure, the drip holes are provided in a staggered arrangement with the drip holes located at the next stage.

To replenish the matrix with electrolytes, in Figure 3,
Electrolyte is replenished into the electrolyte replenishment channel 5, and the electrolyte accumulated in the plate 71 enters the replenishment channel 8, impregnated with a hydrophilic material 9, and replenished into the matrix 1. On the other hand, plate 71
When the electrolyte that remains in
It is dripped onto the lower plate 72 from a, and is replenished to the lower matrix in the same way as described above.

Incidentally, the electrolyte replenishment channel 8 is made impermeable or treated to be water repellent so that the electrolyte does not penetrate into the gas diffusion region within the electrode and impede the power generation action. Further, the electrolyte replenishment passage 7 in the vertical direction is also treated to be water repellent to prevent liquid tangling caused by the electrolyte. however,
In the electrolyte replenishment passage that has been treated with water repellent treatment as mentioned above,
A certain amount of electrolyte liquid pressure is required to drip the electrolyte from the drip hole of the liquid receiver, and the distance between the liquid receivers must be large to prevent a liquid junction caused by a lump of stagnant electrolyte coming into contact with the upper plate. However, there is a disadvantage that the electrolyte replenishment structure becomes large. Furthermore, when the electrolyte is dripped, there is a problem in that liquid junctions occur for reasons explained below.

FIGS. 5 and 6 are cross-sectional views showing a state in which a liquid junction occurs when electrolyte is dripped from the drip hole of the plate. In FIG. 5, when the droplet '71b dripping from the dripping hole '71a of the plate 71 drops one after another, since the grate etc. have water repellency, the droplet 'I
t) gathers to form a large droplet mass '72. As this state progresses further, as shown in FIG. 6, the droplet mass 'i'21) flows all at once and flows out of the drip hole 72a, so that the plates 2 and 73 are connected through the liquid column 72d. ,
play) A liquid junction occurs via an electrolyte (not shown) that remains at 'i'2 and 73. This has the disadvantage of causing electrolytic corrosion of the materials constituting the fuel cell, such as carbon materials. In order to eliminate this drawback, it is necessary to increase the interval between the sibrates, and conventionally it has been difficult to replenish electrolyte without causing a liquid junction during operation of the fuel cell.

[Object of the Invention] In view of the above-mentioned drawbacks, an object of the present invention is to provide an electrolyte replenishment structure that does not cause electrolyte junctions when replenishing electrolyte to a matrix by dropping it through a vertical electrolyte passage. do.

[Key points of the invention]

According to the present invention, a plurality of liquid receivers having holes are provided in an electrolyte replenishment passage arranged vertically, and the electrolyte is dripped through the holes into a lower liquid receiver. In a device that replenishes the electrolyte accumulated in the matrix through an electrolyte replenishment path communicating with the matrix, each liquid receiver has at least a portion of the hole in the liquid receiver facing and located directly above the hole in the liquid receiver projected vertically. This can be achieved by providing a hydrophilic material.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG.
The same parts as those in the figures to FIG. 6 are given the same reference numerals.

In FIG. 7, matrix 1. Oxidizer electrode 3. Structure of battery consisting of electrode base material 4 with lip etc. and drip hole 11h
.

Play as a liquid receiver with '72a etc.) 71,
The electrolyte passages such as the electrolyte replenishment passage 7 and the electrolyte replenishment passage 8 having the '72 etc. are subjected to water repellent treatment, and their configuration is the same as that described in the prior art section, but the matrix l (play mounted in position) 7
1, '/2, '73 drip hole fla + 72
A covering material 9a made of a hydrophilic material faces up to half of the area of a + 73a, and this covering material 9a is connected to the hydrophilic material 9 filled in the electrolyte supply channel 8. Further, as shown in FIG. 8, a part of the drip hole 71a' directly above is vertically projected onto the covering material 9a (7Jb).

The hydrophilic material used is woven carbon or silicone fibers, or solidified carbon powder.

The area of the covering material 9a facing the dripping hole '72a is preferably O ~ 0. Therefore, as shown in FIG. Alternatively, as shown in FIG. 1θ, the end portion of the sea urchin tongue plate 9a may be cut out to make the area smaller than a spoon.

Now, with the above structure, when electrolyte is replenished from the vertical electrolyte replenishment passage 7, as shown in Figure 1,
For example, the electrolyte droplet 1b dropped through the dripping hole 71a is deposited on the covering material 9a, and since the receiving material 9a has hydrophilic properties, the electrolyte does not form a liquid region but spreads out to form a flat liquid pool. i)
72b, and the liquid can be dripped smoothly without being accumulated in the dripping part. Therefore, communication by a liquid column between the plates as shown in FIG. 6 does not occur, and an electrolyte liquid junction does not occur. This eliminates electrolytic corrosion of carbon materials and the like due to liquid junctions.

In addition, if the covering material 9a faces beyond the area of the drip hole, the holding power of the electrolyte will increase, and there is a risk that the electrolyte will accumulate on the hydrophilic covering material 9a and form a liquid region, which must be avoided. Further, in the above embodiment, the drip holes 71a, 72a, etc. are provided in a staggered manner, but the same effect can be obtained even if the drip holes are arranged on a vertical line.

The hydrophilic coating material of the present invention can also be used in a structure in which a vertical electrolyte replenishment passage connected to each electrolyte replenishment passage is provided outside the cell stack of a fuel cell, and stain solute is dripped through the dripping hole. The same effect can be obtained by placing it facing the drip hole.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, in a structure in which electrolyte is supplied to the matrix by dripping from a hole in a liquid receiver in an electrolyte replenishment passage provided directly, this liquid is added to the liquid receiver. By arranging a hydrophilic covering material that faces the receiving hole and at least a portion of the liquid receiving hole directly above it projects vertically, the droplets that drip from the hole will form large liquids on the hydrophilic covering material. The electrolyte becomes a liquid column between the upper and lower liquid receivers, which are adjacent to each other, as the liquid drips smoothly without any lumps accumulating in the dripping area. There is no risk of liquid junction of the electrolyte, and it becomes possible to replenish the electrolyte during operation of the battery without causing electrolytic corrosion of the structural members constituting the battery, such as carbon material.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of a unit cell constituting a fuel cell, FIG. 2 is a plan view of a ribbed electrode base material equipped with an electrolyte supply channel,
Fig. 3 is a partial sectional view showing an electrolyte replenishment structure according to the prior art, Fig. 4 is a partial plan view of the electrolyte replenishment structure in Fig. 3, and Figs. 5 and 6 are partial sectional views showing a state in which electrolyte is dripped. , FIG. 7 is a sectional view showing an electrolyte replenishment structure according to an embodiment of the present invention, FIG. 8 is a partial sectional view taken along line X-X in FIG. FIG. 11 is a partial sectional view showing the dripping state of electrolyte according to an embodiment of the present invention. 1... Matrix, 7... Electrolyte supply passage, '7
1゜'72, 73...liquid receiver, 71a + 'i
'2a + '73a-...hole, f11)...projected hole, 8...electrolyte supply path, 9a...coating material. 71 figure 2 figure 30 j4 figure (・; '75 figure 6 figure

Claims (1)

[Claims] An electrolyte replenishment method in which a plurality of liquid receivers with holes are provided in an electrolyte replenishment passage arranged vertically, and the electrolyte is dripped from the holes into the lower liquid receiver, and the electrolyte stagnant in the liquid receiver is communicated with the matrix. In the electrolyte replenishment structure for a matrix fuel cell in which the matrix is replenished via a channel, each of the liquid receivers is provided with a hydrophilic material that faces the hole in the liquid receiver and at least a part of the hole in the liquid receiver directly above projects vertically. An electrolyte replenishment structure for a matrix fuel cell, characterized in that: