JPH0652667B2 - Fuel cell - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to replenishment of an electrolyte for a fuel cell, and more particularly to a fuel cell having a function of replenishing the electrolyte from the outside in a stacked fuel cell.

[Conventional technology]

In a fuel cell, a pair of electrodes are arranged on both sides of an electrolyte plate, and a separator having a passage for an oxidant gas and a fuel gas is arranged outside each electrode to form a unit cell.

In order to increase the capacity as a fuel cell for electric power, the electrode area is increased, and a large stacked battery in which a large number of unit batteries are stacked becomes a standard stack.
A power plant of a scale that meets the needs will be built. One of the biggest problems in the operation of fuel cells is the movement of the electrolyte inside the unit cell or the entire laminated cell, the electrolyte wear due to the corrosion of the separator, etc., and the electrolyte itself evaporating and scattering to the outside of the cell. Therefore, there is a problem that the electrolyte becomes insufficient and the battery performance gradually deteriorates. As methods for coping with such problems, various methods have been proposed so far for storing an electrolyte inside a battery and replenishing the electrolyte from the outside.

Examples of the invention relating to the method of storing the electrolyte inside the battery include, for example, JP-A-53-30747, JP-A-56-54770, JP-A-58-100368, and JP-A-58-138268. 58-16
5258, JP-A-58-165262 and JP-A-58-166653 are disclosed.

However, the durability time required for the fuel cell body is generally said to be about 40,000 hours, and it is necessary to maintain stable cell performance for a long period of time, and it is quite possible to achieve that goal with the electrolyte battery internal storage method. Is difficult. Therefore, when the battery performance drops to an arbitrary predetermined value, it becomes necessary to replenish the inside of the battery with the electrolyte from the outside.

Inventions relating to a method of replenishing an electrolyte from the outside are disclosed in JP-A-57-197756, JP-A-58-42179, and JP-A-5-42179.
8-61574, JP-A-58-61575 and JP-A-58-144760 are disclosed, but they have the following problems.

[Problems to be solved by the invention]

In any of these inventions, an electrolyte replenishing port penetrating from the upper part to the lower part of the stacked fuel cell is filled with electrolyte and replenished with electrolyte, and an electrolyte matrix substrate is provided for each unit cell via a passage branched and communicating from the electrolyte replenishing through port. An electrolyte is supplied to the inside of the pores, and various inventions for that purpose are disclosed. However, in the above-mentioned conventional technique, a liquid short circuit occurs in the stacked fuel cell because the electrolyte is filled and replenished to the through holes from the upper part to the lower part.

That is, conventionally, since the electrolyte is supplied from one or a plurality of relatively few electrolyte supply pipes, it takes a considerably long time (several hours to several tens of hours) and the electrolyte permeates into the matrix substrate pores. The liquid was easy to connect between.
Further, in the upper unit cell and the lower unit cell of the stacked fuel cell, there is an influence of the head difference, and it is difficult to uniformly supply a desired amount of electrolyte.

Desirably, a required amount of electrolyte may be separately replenished to each unit battery according to the degree of power generation of the battery performance of each unit battery.

A method of injecting and replenishing the electrolyte from the side surface of the laminated fuel cell to the electrolyte matrix substrate layer of each unit cell has also been devised, for example, JP-A-57-55071 and JP-A-58-158870.
Japanese Patent Laid-Open No. 58-161267 and the like are disclosed.

However, considering that it is desirable to reduce the thickness per unit cell as much as possible, the method of replenishing the electrolyte from the side surface of the laminated fuel cell is limited in space and the external manifold type laminated fuel is used. Practical application is difficult in batteries.

An object of the present invention is to uniformly and smoothly replenish the electrolyte matrix substrate of each unit battery with electrolyte in order to prevent deterioration of battery performance due to lack of electrolyte, so that stable battery performance can be obtained for a long period of time. Another object of the present invention is to provide a fuel cell having an electrolyte replenishing function.

[Means for solving problems]

The above-mentioned problem is that a unit battery in which an electrolyte matrix substrate is sandwiched by a pair of electrodes having a smaller area than the electrolyte matrix substrate is laminated with a separator having substantially the same area as the electrolyte matrix substrate interposed therebetween, and the laminate. A block battery having an upper gas header provided on the upper part of the body and supplying / discharging reaction gas to / from each unit battery, wherein the separator is provided with a reaction gas flow passage facing the electrodes and is provided around the electrodes. In a fuel cell having a wet seal part in contact with an electrolyte matrix substrate, an electrolyte distribution container to which an electrolyte is supplied from the outside, a plurality of electrolyte reservoirs communicating with the electrolyte distribution container, the electrolyte reservoirs and the electrolyte matrix substrates. And the same number of electrolyte introducing tubes as the electrolyte matrix substrate communicating with each other, and the upper gas header sandwiches the electrodes. The reaction gas supply part and the reaction gas discharge part are provided in the upper part of the facing wet seal part, and the reaction gas supply part and the reaction gas discharge part have a region where the reaction gas does not flow in the intermediate part, and the electrolyte distribution container and The electrolyte reservoir is arranged in a region where the reaction gas of the upper gas header does not flow, and the electrolyte introduction pipe penetrates through the wet seal portion and is arranged in the wet seal portion by terminating the individual electrolyte matrix substrate. Solved by a fuel cell that does.

The above-mentioned problem is also a laminated body in which a plurality of unit batteries formed by sandwiching an electrolyte matrix substrate with a pair of electrodes having a smaller area than the electrolyte matrix substrate are laminated with a separator having substantially the same area as the electrolyte matrix substrate interposed therebetween. A block battery having an upper gas header provided at an upper portion of the stack and supplying / discharging a reaction gas to / from each unit cell, wherein the separator has a reaction gas flow passage facing the electrodes and a periphery of the electrodes. In a fuel cell having a wet seal part in contact with the electrolyte matrix substrate, an electrolyte supply means, an electrolyte distribution container to which an electrolyte is supplied from the electrolyte supply means, a plurality of electrolyte reservoirs communicating with the electrolyte distribution container, and An electrolyte introduction tube in the same number as the electrolyte matrix substrate, which communicates each electrolyte reservoir with each electrolyte matrix substrate; Block battery performance detection means for detecting the power generation performance of the battery, and an electrolyte supply command means for outputting an electrolyte supply command to the electrolyte supply means by the detection signal of the block battery performance detection means, the upper gas header is the The reaction gas supply part and the reaction gas discharge part are provided in the upper part of the wet seal part facing each other across the electrode, and the reaction gas has a flow or region in the intermediate part of the reaction gas supply part and the reaction gas discharge part. The electrolyte distribution container and the electrolyte reservoir are arranged in a region where the reaction gas of the upper gas header does not flow, and the electrolyte introduction pipe penetrates through the wet seal portion and is arranged in the wet seal portion with an individual electrolyte matrix substrate as a termination. It is solved by a fuel cell characterized by the above.

[Action]

The upper gas header of the block battery has a portion in which a reaction gas does not flow in the central portion, and in the portion, an electrolyte distribution container and a plurality of electrolyte reservoirs communicating with it and corresponding to individual unit cells are compactly housed. The electrolyte is independently supplied from a plurality of electrolyte reservoirs to the electrolyte matrix substrate of each unit cell while maintaining a high temperature by means of individual electrolyte introduction tubes penetrating the wet seal portion. The electrolyte is replenished to each electrolyte matrix substrate at the wet seal portion.

Further, the battery performance detecting means monitors the power generation performance of the battery and detects the electrolyte replenishment time, so that the electrolyte can be automatically supplied when necessary.

〔Example〕

An embodiment according to the present invention will be described below with reference to FIGS.

Example 1 FIG. 1 shows an electrolyte matrix substrate 3-1 which holds an electrolyte between a pair of electrodes composed of a fuel electrode 1-1 and an oxidizer electrode 2-1 and is provided outside each electrode. 1 is an example showing an electrolyte external replenishment structure in a stacked fuel cell 5 in which n unit cells in which a separator 4-1 having fuel gas and oxidant gas flow passages is arranged are stacked.
Here, the upper end plate 6, the lower end plate 7, the upper gas header 8, and the lower gas header 9 of the n-piece stacked fuel cell 5 are integrated with each other through the sealing materials 10 and 11.
The gas headers 8 and 9 are the second ones shown in the section AA 'in FIG.
As can be seen from the figure, each has a fuel gas supply unit 12, a fuel gas discharge unit 13, an oxidant gas supply unit 14, and an oxidant gas discharge unit 15, and the fuel gas is the fuel gas supply pipe shown in FIG. After passing through the fuel gas supply unit 12 from the fuel gas supply unit 12 to the fuel electrodes 1-1 to 1-n side of each unit cell, the fuel gas is discharged from the fuel gas discharge pipe 17 through the fuel gas discharge unit 13. In FIG. 1, the supply and discharge pipes of the oxidant gas are omitted, but like the fuel gas, the oxidant gas is discharged after flowing through the oxidant electrodes 2-1 to 2-n side of each unit cell. .

In the embodiment shown in FIGS. 1 and 2, an electrolyte replenishing mechanism is provided in a hollow portion in the upper gas header 8 disposed above the laminated fuel cell 5 in which a reaction gas does not flow. That is, the electrolyte distribution container 18 is located in the central portion,
The electrolyte is supplied to the electrolyte distribution container 18 from the outside of the main body of the stacked fuel cell 5 through the electrolyte supply pipe 19. The supplied electrolyte is evenly distributed to the electrolyte reservoir 20 communicating with each unit cell, passing through a narrow channel passage 21 provided in the periphery of the electrolyte distribution container 18. The evenly distributed electrolyte is provided with a communication hole 2 provided in each electrolyte reservoir 20.
Electrolyte replenishment passage 23 which is guided in the horizontal direction via 2
Electrolyte matrix substrates 3-1 to 3-n of the unit cells that pass through the laminated fuel cell 5 in the vertical direction.
Each of the unit cells terminates in an independent electrolyte introduction tube 24-1 to 24-n, reaches the electrolyte matrix substrate section 3 of each unit battery, and is uniformly permeated and impregnated into the pores. The installation position of the electrolyte distribution container 18 is not particularly limited, but as shown in FIG. 1, it is preferable to provide the electrolyte distribution container 18 in a hollow portion in the gas headers 8 and 9 where the reaction gas does not flow.

The electrolyte replenishing passage 23, which is guided in the horizontal direction from the electrolyte reservoir 20, may be provided inside the gas header and communicate with the electrolyte introducing pipe 24 penetrating in the vertical direction through the communicating hole 22. In addition, the electrolyte reservoir 20
May be provided at the bottom of the gas header 8 or at the upper part of the separator 4 immediately below the gas header 8 through the communication hole 22 and communicated with the electrolyte introduction pipe 24 from there.

The electrolyte introduction tube 24 is usually provided so as to penetrate the gas seal portion of the battery. In the case of a wet seal, the separator 4 and the matrix electrolyte substrate up to the point where the electrolyte matrix substrate 3 of each unit battery is terminated. The electrolyte introduction tube 24 is formed by providing a through hole in 3 and communicating them.

As described above, the electrolyte introduction tube 24 is usually provided so as to penetrate the laminated fuel cell peripheral sealing portion, but as shown in FIG. 6, the electrolyte introduction tube 24 is provided in the same separator surface that enables the area of the cell to be increased. In the case of a battery in which a plurality of unit batteries are formed, the electrolyte introduction tube 24 may be formed not only in the laminated battery peripheral sealing portion but also in the central sealing portion.

Up to now, it has been stated that the electrolyte replenishment to each unit battery is carried out from the electrolyte reservoir 20 through the electrolyte replenishment passage 23 and the electrolyte introduction pipe 24, but the passage does not necessarily have to be one, and the battery has a large area. If so, it is possible to form a plurality of passages for each unit cell.

Naturally, this embodiment can be applied to various fuel cells using a liquid electrolyte, such as phosphoric acid type and molten salt type fuel cells.

According to the method of the present embodiment, it is possible to uniformly replenish the electrolyte from the outside to each unit cell, and it is possible to prevent a liquid short circuit. Of course, it can be carried out even when the battery is operating.

Example 2 In FIG. 5, about 20 to 25 cell laminated battery is regarded as one block,
It is a schematic diagram of a multi-block laminated battery stack in which two blocks are laminated with a gas header 9 installed in the middle. Also in this case, it is possible to replenish the upper block with the electrolyte from the uppermost gas header 8 and replenish the lower block with the intermediate gas header 9 in the same manner as in the first embodiment. In this embodiment, the electrolyte replenishment can be controlled and executed in block units.

In this way, a stacked fuel cell with several cells or several tens of cells
Even in the case of a large-capacity stack formed by stacking a plurality of blocks through intermediate gas headers, the electrolyte distribution container 18 can be installed in the hollow portion of the upper gas header 8 of each block, and each block can be installed. Alternatively, it is possible to supply the electrolyte to all blocks.

Example 3 The electrolyte supplying device and the supplying procedure will be described with reference to FIGS. 3 and 4.

FIG. 3 shows the contents of the above-mentioned block batteries which are detected and the electrolyte is supplied to each block battery when the performance is lower than a predetermined value.

FIG. 4 shows an embodiment in which the performance of each unit battery is detected and an electrolyte is supplied if necessary. The contents of this embodiment will be described below with reference to FIG. The supply of the electrolyte is started when the set value of the signal is reached based on the magnitude of various signals that can detect the lack of the electrolyte. Examples of means of the block battery performance detector 30 include an open circuit voltage, an internal resistance, a gas leak rate or an O ₂ concentration in a fuel gas or an H ₂ concentration in an oxidant gas for detecting a gas cross. The value of at least one of these signals is monitored, and when the set value is reached, the electrolyte melted according to a command from the electrolyte supply command device 31 is supplied from the outside of the laminated fuel cell main body to the block battery electrolyte supply device 32.
Is supplied to the electrolyte distribution container 18. The electrolyte can be supplied in the molten state from the outside of the bell jar that houses the gas pipe, the detection terminal, the current extraction terminal, the electrolyte supply pipe, the electrolyte receiving hopper, etc., or a predetermined amount of electrolyte can be supplied. It is also possible to supply in a solid state, melt in the bell jar, and supply to the electrolyte distribution container 18. As described above, the supply of the electrolyte can be performed while the battery is operating, but another method is to stop the battery operation and lower the temperature, for example, just before stopping the battery of the detection signal of the block battery performance detector 30 at the time of regular inspection. Based on the value, it is also possible to supply a predetermined amount of electrolyte in a solid state to each unit battery electrolyte reservoir 20 branched from the electrolyte distribution container 18 in the hollow portion of the gas header 8.

The above description is a method of detecting the signal for each block of the battery stack and performing electrolyte replenishment in block units, but in some cases, as shown in FIG. 4, the signal of each unit battery in one block is It is also possible in the laminated fuel cell of the present invention to detect the temperature and supply the electrolyte only to a specific unit cell in the block. The detailed procedure is the same as in the case of the block battery of FIG. 3 and therefore omitted, but when this method is carried out, a plurality of electrolyte supply pipes 24 corresponding to the number of unit batteries stacked in one block are provided. The electrolyte can be replenished only to the cells that reach the set value by detecting the signal by guiding the gas to the upper part of the electrolyte reservoir 20 in the center of the gas header 8.

The electrolyte can be supplied at a predetermined amount all at once, or can be dividedly supplied at regular intervals.

The most characteristic feature of the first to third embodiments is that the electrolyte to be replenished is distributed almost evenly in the upper part of the stacked fuel cell, and the electrolyte passages are provided independently for each unit cell. That is, the electrolyte can be surely replenished for each unit battery. According to the method of the present embodiment, the electrolyte can be evenly supplied to each unit cell, and the liquid short circuit which can occur in the conventional method can be prevented.

〔The invention's effect〕

According to the present invention, the electrolyte is supplied to each electrolyte matrix substrate of the fuel cell independently through the electrolyte introduction path, so that the possibility of liquid short circuit is significantly reduced, and the output variation between the unit cells can be reduced. It is possible to improve the reliability and operating rate of the battery. Further, there is an excellent effect that the battery performance can be stabilized for a long period of time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a fuel cell showing an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1, and FIGS. FIG. 5 is a block diagram showing the device, FIG. 5 is a perspective view when the block batteries are stacked, and FIG. 6 is a perspective view showing the concept of the multi-cell. DESCRIPTION OF SYMBOLS 1 ... Fuel electrode, 2 ... Oxidizer electrode, 3 ... Electrolyte matrix substrate, 8 ... Upper gas header, 9 ... Lower gas header, 18 ...
Electrolyte distribution container, 20 ... Electrolyte reservoir, 24 ... Electrolyte introduction path, 30 ... Block battery performance detector, 31 ... Electrolyte supply command device, 32 ... Block battery electrolyte supply device, 40
... Unit battery performance detector, 41 ... Electrolyte supply command device, 4
2 ... Electrolyte supply device for unit battery.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Miyoshi 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitate Works Ltd., Hitachi Research Laboratory (72) Inventor Yoshio Iwase 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitate Works Co., Ltd. Hitachi Research Laboratory (72) Inventor Satoshi Kuroe 4026 Kuji Town, Hitachi City, Ibaraki Prefecture, Hitate Works, Ltd. Hitachi Research Laboratory (72) Inventor Yuichi Kamo 4026 Kuji Town, Hitachi City, Ibaraki Prefecture, Hitachi Research Institute, Ltd. (56) References JP-A-60-241659 (JP, A) JP-A-61-227370 (JP, A) JP-A-62-115668 (JP, A) JP-A-61-156637 (JP, A)

Claims (6)

[Claims] 1. A laminate in which a plurality of unit batteries, each of which has an electrolyte matrix substrate sandwiched by a pair of electrodes having an area smaller than that of the electrolyte matrix substrate, are laminated with a separator having substantially the same area as the electrolyte matrix substrate interposed therebetween, and the laminate. A block battery having an upper gas header provided on the upper part of the body and supplying / discharging reaction gas to / from each unit battery, wherein the separator is provided with a reaction gas flow passage facing the electrodes and is provided around the electrodes. In a fuel cell having a wet seal part in contact with an electrolyte matrix substrate, an electrolyte distribution container to which an electrolyte is supplied from the outside, a plurality of electrolyte reservoirs communicating with the electrolyte distribution container, the electrolyte reservoirs and the electrolyte matrix substrates. And the same number of electrolyte introducing tubes as the electrolyte matrix substrate communicating with each other, and the upper gas header is paired with the electrode sandwiched therebetween. The reaction gas supply part and the reaction gas discharge part are provided in the upper part of the facing wet seal part, and the reaction gas supply part and the reaction gas discharge part have a region where the reaction gas does not flow in the intermediate part, and the electrolyte distribution container and The electrolyte reservoir is arranged in a region where the reaction gas of the upper gas header does not flow, and the electrolyte introduction pipe penetrates through the wet seal portion and is arranged in the wet seal portion by terminating the individual electrolyte matrix substrate. Fuel cell to do. 2. The fuel cell according to claim 1, wherein a plurality of the block cells are stacked. 3. The fuel cell according to claim 1, wherein a plurality of unit cells are formed in the same separator surface. 4. A laminate in which a plurality of unit cells, each of which has an electrolyte matrix substrate sandwiched by a pair of electrodes having a smaller area than the electrolyte matrix substrate, are laminated with a separator having substantially the same area as the electrolyte matrix substrate interposed therebetween, and the laminate. A block battery having an upper gas header provided on the upper part of the body and supplying / discharging reaction gas to / from each unit battery, wherein the separator is provided with a reaction gas flow passage facing the electrodes and is provided around the electrodes. In a fuel cell having a wet seal part in contact with an electrolyte matrix substrate, an electrolyte supply means, an electrolyte distribution container to which an electrolyte is supplied from the electrolyte supply means, a plurality of electrolyte reservoirs communicating with the electrolyte distribution container, and each of the electrolytes. Reservoirs and the electrolyte matrix substrates, the same number of electrolyte introduction tubes as the electrolyte matrix substrates, and the block electrodes. Block battery performance detection means for detecting the power generation performance of the pond, and an electrolyte supply command means for outputting an electrolyte supply command to the electrolyte supply means by a detection signal of the block battery performance detection means,
The upper gas header has a reaction gas supply part and a reaction gas discharge part in an upper part of the wet seal part facing each other with the electrode sandwiched therebetween, and a reaction gas flows or a region in an intermediate part between the reaction gas supply part and the reaction gas discharge part. And the electrolyte distribution container and the electrolyte reservoir are arranged in a region of the upper gas header where the reaction gas does not flow, and the electrolyte introduction pipe penetrates the wet seal portion and terminates an individual electrolyte matrix substrate in the wet seal portion. A fuel cell characterized by being arranged as. 5. The fuel cell according to claim 4, wherein a plurality of the block cells are stacked. 6. The fuel cell according to claim 4 or 5, wherein a plurality of unit cells are formed in the same separator surface.