JPH0677462B2 - Electrolyte replenishing device for matrix fuel cell - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a matrix layer formed by vertically stacking unit cells holding an electrolyte in a porous matrix layer on a vertical side surface of the cell stack. The present invention relates to an electrolyte replenishing device for a matrix fuel cell in which a communicating electrolyte replenishing path is led out for each single cell.

[Prior art and its problems]

In the matrix type fuel cell, the electrolyte carried by the matrix layer evaporates and scatters as the fuel cell continues to operate, so that it becomes necessary to replenish the electrolyte when the operating time of the fuel cell becomes long. Various structures have been proposed as the electrolyte replenishing device. A conventional electrolyte replenishing device will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing an example of a cell of a matrix type fuel cell. In the figure, reference numeral 1 is a matrix layer supporting an electrolyte, and a fuel electrode 2 and an oxidizer electrode 3 are arranged on both sides of the matrix layer. There is. Outside the fuel cell 2 and the oxidizer electrode 3, a porous ribbed electrode substrate 4 having a groove 4a provided in the direction of arrow A, and a porous material having a groove 5a provided in a direction orthogonal to the groove 4a. And a ribbed electrode substrate 5 are provided, and the fuel electrode 2 and the oxidant electrode 3 are provided, respectively.
And the matrix layer 1 to form a unit cell. Separate plate 6 with no gas expansion between these cells
Is interposed to separate the reaction gas, and a large number of these are stacked to form a cell stack. Fuel gas as a reaction gas flows from the direction of arrow A and oxidant gas flows from the direction of arrow B to the grooves 4a and 5a of the ribbed electrode substrates 4 and 5, respectively, and is supplied to each electrode to generate electricity.

However, as the operating time of the fuel cell becomes longer, the amount of electrolyte carried on the matrix layer decreases due to evaporation and scattering of the electrolyte, so it is necessary to replenish the electrolyte during the service period. As an example of the replenishing structure for this purpose, the applicant previously proposed the one shown in FIG. 2 in Japanese Patent Application No. 83-92570. In FIG. 2, the unit cell is composed of a matrix layer 1, a fuel electrode 2, an oxidizer electrode 3, and ribbed electrode base materials 4 and 5, and a cell stack is formed by stacking a separate plate 6 between the unit cells. Are configured. The electrolyte replenishment passage 8 and the matrix layer 1 are provided on the ribbed electrode substrate 4 on the fuel electrode side of each unit cell.
An electrolyte replenishing hole 12 communicating with the above is provided. Electrolyte passages 13 communicating with the electrolyte replenishing passages of the adjacent lower unit cells are provided on both sides of the matrix layer 1 in a staggered arrangement.

To supply electrolyte to the matrix layer, the electrolyte passage 13
The electrolyte is replenished through the inlet 13a. Then, the electrolyte fills the electrolyte replenishment passage 8 of the upper unit cell, and the electrolyte replenishment hole 12
The electrolyte is supplied to the matrix layer 1 through the electrolyte. When the replenishment of the upper matrix layer is completed, the overflowed electrolyte flows through the electrolyte passage 13 communicating with the electrolyte replenishing passage 8 of the next unit cell, and the electrolyte is replenished to the matrix layer of the next unit cell. In this procedure, the electrolyte is replenished to all matrix layers of the cell stack sequentially.

As another example of the electrolyte replenishing structure, the applicant previously described in Showa 59
Fig. 3 is proposed in "Electrolyte replenishment structure of matrix fuel cell" filed on March 21, 2014. In FIG. 3, the unit cell includes a matrix layer 1, a fuel electrode (not shown), an oxidizer electrode 3, and electrode base materials 4 and 5 with ribs. Then, the ribbed electrode base material 4 on the fuel electrode side is communicated with the matrix layer 1, filled with a hydrophilic material 9 having a capillary force and provided with an electrolyte replenishing passage 8 to form a cell stack, and the cell stack is laminated in the stacking direction. An electrolyte passage 7 penetrating through is provided, and an electrolyte receiver 71 having a hole 71a provided in the passage is provided for each unit cell.

When the electrolyte is replenished from the upper portion of the electrolyte passage 7, the electrolyte flows into the electrolyte replenishing passage 8 while staying in the electrolyte receiver 71, and is replenished to the matrix layer 1 through the hydrophilic material 9. Then, the electrolyte retained in the electrolyte receiver is dropped from the small hole 71a of the electrolyte receiver 71 to the electrolyte receiver 72 therebelow, and the matrix layer at that stage is replenished with the electrolyte in the same manner as above, and at the same time, the electrolyte receiver at the lower stage. After dropping, the electrolyte is replenished to each matrix layer of the cell stack sequentially by this procedure.

In the replenishment structure as described above, the diameter of the hole for guiding the electrolyte to the lower unit cell, that is, the diameter of the electrolyte passage 13 in FIG. 2 and the hole 71a for the electrolyte receiver in FIG. A small hole of about 2 mm is used to limit the amount of liquid junction that causes electrolytic corrosion and output loss. Therefore, when the above small holes are closed due to the inclusion of dust in the electrolyte during the operation of the fuel cell for a long time, the cell stack, the manifold, etc. must be disassembled to restore the function of the electrolyte replenishment structure. There was still room for improvement in terms of maintainability.

[Object of the Invention]

In view of the above points, it is an object of the present invention to provide an electrolyte replenishing structure that is easy to inspect and maintain even if the electrolyte replenishing hole is closed.

[Summary of Invention]

The above-mentioned object is a vertical cell stack in which a plurality of unit cells holding an electrolyte in a matrix layer interposed between two ribbed electrode base materials having a fuel electrode or an oxidizer electrode are vertically stacked. In the electrolyte replenishing device for a fuel cell, in which an electrolyte replenishing path communicating with the matrix layer is led out for each unit cell on a side surface, at least one of the ribbed electrode base materials is provided as a container having an upper surface opened. A formed electrolyte receiver is provided, the inside of the electrolyte receiver is made to communicate with the electrolyte replenishing path, and a small hole suitable for dropping the electrolyte downward is provided at the bottom of the extending portion of the electrolyte receiver. The supply passage and the electrolyte receiver are filled with a hydrophilic material having a capillary force, and the electrolyte receiver is attached to the side surface of the cell stack. The electrolytic receivers, which are provided in a side surface portion isolated from the external reaction gas and are vertically aligned, are hermetically covered by a common protective cover that is separate from the manifold lid. .

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a plan view of a ribbed electrode base material on the fuel electrode side according to an embodiment of the present invention. 4 and the subsequent figures, the same parts as those in FIGS. 1 to 3 are designated by the same reference numerals. Fourth
In the figure, it communicates with an electrolyte replenishing passage 8 communicating with the matrix layer provided on the ribbed electrode substrate 4, and has a hole 71a at the bottom.
An electrolyte receiver 71, which forms a container-like body provided with, protrudes from the side surface of the rib secondary electrode substrate 4. The electrolyte replenishing passage 8 and the electrolyte receiver 71 are integrally manufactured, and a flow-through portion of the electrolyte is made of a hydrophilic material 9 having electrolyte resistance and capillary force, for example, a woven fiber of an inorganic material, or It is filled with materials equivalent to Matricex. The electrolyte receiver 71 may be provided on the ribbed electrode base material on the oxidizer electrode side.

FIG. 5 is a perspective view of a fuel cell constructed by incorporating the ribbed electrode base material provided with the electrolyte receiver of FIG. In FIG. 5, the unit cell comprises a ribbed electrode base material 4 provided with fuel electrodes and projecting electrolyte receivers 71 arranged on both sides of the matrix layer 1, and a ribbed electrode base material 5 provided with an oxidizer electrode. A separate plate 6 is interposed between the unit cells, and a large number of these are stacked to form a cell stack. A manifold 14 for fuel gas supply is provided so as to cover the groove 4a of the ribbed electrode substrate 4 through which the fuel gas flows, with an O-ring packing 14a interposed between the manifold 14 and the sealing surface 18. . Although not shown, a manifold for exhausting the fuel gas is provided on opposite side surfaces of the manifold 14. Further, an oxidant gas supply manifold 15 orthogonal to the groove 4a through which the fuel gas flows is attached to the side surface of the cell stack, and an oxidant gas exhaust manifold is attached to the opposite cell stack side surface of this manifold (not shown). Has been.

The electrolyte receiver 71 provided in each cell of the cell stack is
The protective cover 16 is arranged in the vertical direction so as to project from the outside of the manifold 14, that is, the side surface of the cell stack that is outside the compartment of the manifold for supplying and discharging the reaction gas, and covers all of these electrolyte receivers 71 in a hermetically sealed manner. It is attached via a sealing surface 17 and an O-ring packing 16a. The protective cover 16 has holes (not shown) that can be opened and closed at the top and bottom to serve as an electrolyte supply port and an electrolyte discharge port, respectively. In addition, the portion of the protective cover 16 that contacts the electrolyte, including the supply port and the exhaust port, is subjected to a corrosion resistance treatment such as a fluororesin treatment or a ceramic coat.

Now, in order to replenish the matrix to the electrolyte, if the electrolyte is replenished from the replenishing port at the top of the protective cover and the electrolyte is supplied on the electrolyte receiver 71, the electrolyte on the electrolyte receiver 71 is the electrolyte through the hydrophilic material. It is replenished to the Matricex from the supply route. Then, the electrolyte dropped from the hole 71a of the electrolyte receiver 71 stays in the electrolyte receiver in the lower stage and is replenished to the matrix layer in this stage in the same manner as described above, and is further dropped in the electrolyte receiver in the lower stage in this way. Then, the electrolyte is supplied to all of the matrix layers of the cell stack. This replenishment can be done while the fuel cell is in operation and when it is not in operation. However, in the case of non-operation, the exhaust port of the protective cover is closed to replenish the electrolyte from the replenishment port, and the electrolyte is dropped through the holes in the electrolyte receiver. It is possible to fill the inside of the protective cover with an electrolyte and replenish each matrix of the cell stack with the electrolyte at a time without using the method.

〔The invention's effect〕

As is clear from the above description, according to the present invention, a plurality of unit cells holding an electrolyte in a matrix layer interposed between two ribbed electrode base materials provided with a fuel electrode or an oxidizer electrode are vertically arranged. In a fuel cell electrolyte replenishing device in which an electrolyte replenishment path communicating with the matrix layer is led out for each unit cell on a vertical side surface of a cell stack laminated in the direction, at least one of the ribbed electrode base materials is provided. An electrolyte receiver formed as a container with an open upper surface is provided so that the inside of the electrolyte receiver communicates with the electrolyte replenishing path and the electrolyte is dropped downward at the bottom of the extension of the electrolyte receiver. Is provided with a small hole, the electrolyte supply path and the electrolyte receiver are filled with a hydrophilic material having a capillary force, and the electrolyte receiver is attached to the side surface of the cell stack. Provided in a portion of the side surface that is isolated from the reaction gas outside the supply and discharge manifold compartment response gas,
In addition, when the electrolytic receptacles arranged in the vertical direction are hermetically covered by a common protective cover that is separate from the manifold lid, when the electrolyte holes are blocked by foreign matter such as dust, a cell stack is formed. Since it is provided on the outside of the side surface, it is possible to access it, and it is possible to perform inspection and maintenance easily and to smoothly replenish the electrolyte. Also, since the electrolyte receiving to each stage of the electrolyte to be supplied to each matrix is done by dropping, no liquid junction of the electrolyte occurs, and since it is provided outside the cell stack, the electrolyte can be supplied at any time during the service period. effective. Further, the ribbed electrode base material is integrally provided with an electrolyte receiver having an extension communicating with the electrolyte replenishing passage, so that the structure of the electrolyte replenishing device is simplified, and the capillary force is applied to the electrolyte receiving and electrolyte replenishing passages. By filling the hydrophilic material with the above, it is possible to surely replenish the electrolyte without causing a head difference shortage.

Further, the following effects are obtained by the configuration in which the electrolytic receptacles arranged in the vertical direction are hermetically covered by a common protective cover that is separate from the manifold lid. That is, during power generation of the fuel cell, pressure control is required inside the manifold to supply and exhaust a predetermined amount of reaction gas, but in the configuration in which the electrolyte supply device is provided inside the manifold as in the conventional device, the pressure control is external. There was a problem of disturbing the internal pressure when replenishing the electrolyte from.

On the other hand, in the present invention, since the electrolyte replenishing device is provided separately from the manifold lid, the above problems can be solved and the replenishing operation can be performed regardless of the operation of the battery.

In addition, there is an advantage that maintenance such as inspection for the clogging of the liquid drop hole and cleaning can be easily performed.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a unit cell of a matrix fuel cell, FIGS. 2 and 3 are partial sectional views of an electrolyte replenishing structure according to the prior art, and FIG. 4 is provided with an electrolyte receiver according to an embodiment of the present invention. FIG. 5 is a partial plan view of the electrode base material, and FIG. 5 is a partial perspective view showing an embodiment of the present invention. 1: Matrix, 8: Electrolyte supply path, 71, 72: Electrolyte receiving, 71
a, 72a: hole.

Front page continuation (72) Inventor Noriyuki Nakajima 2-2-1 Nagasaka, Yokosuka City, Kanagawa Prefecture Fuji Electric Research Institute Co., Ltd. (72) Inventor Masahiro Sakurai 2-2-1 Nagasaka, Yokosuka City, Kanagawa Fuji Electric Research Institute Co., Ltd. (56) Reference JP-A-58-164151 (JP, A) JP-A-58-103784 (JP, A)

Claims (1)

[Claims] 1. A cell stack vertical structure in which a plurality of unit cells holding an electrolyte in a matrix layer interposed between two ribbed electrode base materials each having a fuel electrode or an oxidizer electrode are vertically stacked. In the electrolyte replenishing device for a fuel cell, in which an electrolyte replenishing path communicating with the matrix layer is led out for each unit cell on a side surface, at least one of the ribbed electrode base materials is provided as a container having an upper surface opened. A formed electrolyte receiver is provided, the inside of the electrolyte receiver is made to communicate with the electrolyte replenishing path, and a small hole suitable for dropping the electrolyte downward is provided at the bottom of the extending portion of the electrolyte receiver. The supply channel and the electrolyte receiver are filled with a hydrophilic material having a capillary force, and the electrolyte receiver is attached to the side surface of the cell stack. Is provided in a side surface portion isolated from the reaction gas and vertically arranged, and the electrolytic receivers are hermetically covered by a common protective cover which is separate from the manifold lid. Electrolyte replenishing device for matrix fuel cells.