JPS62229665A - Electrolyte circulating type secondary cell - Google Patents

Abstract

PURPOSE:To make the whole device compact and secure a stable charge and discharge, by furnishing two flexible bag-form containers i. an electrolyte tank, feeding the electrolyte from one side container to the electrode in a charge or discharge operation, and returning the electrolyte to the other side container after a reaction is over. CONSTITUTION:Flexible bag-form containers 11 and 12 with a variable capacity depending on the amount of the storing electrolyte stored in an electrolyte tank 13 are accommodated within the electrolyte tank 13. Between the inner wall of the tank 13 and the outer walls of the containers 11 and 12, an inert gas is filled. In a charging, the electrolyte in the container 11 is fed into the positive electrode cell 1a in the electrode 1, and after the electrode reaction with the positive electrode 3 is over, the electrolyte is returned to the tank 13 to be stored in the container 12. In the discharge operation, the electrolyte in the container 12 is fed to the cell 1a, and returned to the tank 13 to be stored in the container 11 after the electrode reaction is over. The same composition is applied at the negative electrode 4 side in the electrode 1. By feeding the electrolyte of a constant active substance density, a stable charge and discharge operation can be carried out, as well as making the whole device size compact.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrolyte flow type secondary battery that is charged and discharged by flowing an electrolyte from an electrolyte tank into an electrode part.

[Prior Art] Japanese Patent Publication No. 59-13153 discloses a four-tank redox flow battery as an electrolyte flow type secondary battery. A schematic diagram of this four-tank redox flow battery is shown in FIG. 2. In FIG. 2, inside the electrode section 1,
It is separated by a diaphragm 2 into a positive electrode cell 1a and a negative electrode cell 1b. A positive electrode 3 is installed in the positive electrode cell 1a, and a negative electrode 4 is installed in the negative electrode cell 1b. Positive electrode cell 1
In a, there are tanks 5 and 6 for storing electrolyte.
are connected to each other. Similarly, a tank 7 and a tank 8 for storing electrolyte are connected to the negative electrode cell 1b, respectively. A pump 9 is installed between the positive electrode cell 1a and the tank 5, and a pump 10 is similarly installed between the negative electrode cell 1b and the tank 7.

During charging and discharging, an electrolytic solution containing a positive electrode active material is supplied to the positive electrode cell 1a, and an electrolytic solution containing a negative electrode active material is supplied to the negative electrode cell 1b. The function of each tank will be described below. In this four-tank redox flow battery, the positive electrode side and the negative electrode side are configured in the same manner and operate in the same manner, so only the positive electrode side will be described.

When charging, an electrolyte is stored in the tank 5,
This electrolytic solution is supplied into the positive electrode cell 1a by the pump 9. The electrolytic solution supplied into the positive electrode cell Ia undergoes an electrode reaction with the positive electrode 3, and then is discharged into the tank 6. Therefore, during charging, the electrolyte in tank 5 moves to tank 6.

During discharge, the electrolytic solution in the positive electrode cell 1a is discharged into the tank 5 by the pump 9, so that the electrolytic solution in the tank 6 is supplied into the positive electrode cell 1a and causes an electrode reaction with the positive electrode 3.

Therefore, the electrolytic solution in the tank 6 moves into the tank 5, thereby causing discharge.

As explained above, in a 4-tank redox flow battery, the electrolyte in one tank moves to the other tank during charging and discharging, so the electrolyte discharged from the electrode part as in the 2-tank type returns to the same level. The electrolyte does not return to the tank and mix with each other.

Therefore, in the four-tank type, an electrolytic solution with a constant concentration of active material and the like is supplied into the electrode section, so the battery voltage is more stable and the energy conversion efficiency is higher than in the two-tank type.

[Problems to be solved by the invention] As described above, the 4-tank type redox flow battery has superior characteristics compared to the 2-tank type. However, each tank can store the entire amount of electrolyte. 2 for the electrode
Requires one. Therefore, compared to a two-tank type, there is a problem in that the entire device becomes larger.

Additionally, there is also the problem of increased manufacturing costs.

Therefore, an object of the present invention is to provide an electrolyte flow-through type that is capable of supplying an electrolyte with a constant concentration of active material to the electrodes to perform stable charging and discharging, as well as the conventional four-tank type, and that is also miniaturized. The purpose is to provide secondary batteries.

[Means for Solving the Problems] In the electrolyte flow type secondary battery of the present invention, the electrolyte tank includes a flexible tank whose volume changes depending on the amount of electrolyte stored. A first bag-like container and a second bag-like container are provided. The first bag-like container and the second bag-like container are each connected to an electrode section. When charging,
The electrolytic solution in the first bag-like container is supplied to the electrode section, and after reaction returns to the electrolytic solution tank and stored in the second bag-like container.

On the contrary, during discharge, the electrolytic solution in the second bag-like container is supplied to the electrode section, and after the reaction returns to the electrolytic solution tank and stored in the bag-like container @1.

[Function] In the electrolyte flow type secondary battery of the present invention, the first
The electrolyte in the bag-like container moves into the second bag-like container.

The first bag-like container and the second bag-like container each have flexibility such that their volumes change depending on the amount of electrolyte stored therein. Therefore, during charging, the first bag-like container gradually becomes smaller as the electrolyte flows out, while the second bag-like container gradually becomes larger as the electrolyte flows in. However, since the overall amount of electrolyte does not change, the combined size of the first bag-like container and the second bag-like container is always constant.

On the contrary, during discharge, the electrolyte in the second bag-like container moves to the first bag-like container.

Therefore, in the electrolyte flow type secondary battery of the present invention, as in the conventional four-tank type, an electrolyte having a constant concentration of active material is supplied into the electrode portion. Moreover, since the combined size of the first bag-like container and the second bag-like container is always constant, the electrolyte tank that accommodates them may be large enough to store the entire amount of electrolyte.

[Embodiment] FIG. 1 is a schematic diagram showing an embodiment of the present invention. Although FIG. 1 shows only the positive electrode side, the negative electrode side is also constructed in the same manner. In FIG. 1, inside the electrolyte tank 13, there are a first bag-like container 11 and a second bag-like container 12.
is stored.

Each bag-like container is made of a material such as rubber woven fabric, and has flexibility such that its volume changes depending on the amount of electrolyte stored therein.

In the state shown in FIG. 1, electrolyte is stored in both the first bag-like container 11 and the second bag-like container 12. The inner wall of the electrolyte tank 13, the first bag-like container 11 and the second
An inert gas such as nitrogen gas is filled between the bag-like container 12 and the outer wall thereof. A pipe 21 is connected to the first bag-shaped container 11, and the pipe 21 is branched into a pipe 23 and a pipe 22. The pipe 22 is connected to a pipe 24 via a pump 14, and the pipe 22 is connected to a pipe 24 via a pump 14.
A valve 31 is installed in the middle of 2.

The pipe 24 is connected to the positive electrode cell la in order to supply electrolyte into the positive electrode cell la of the electrode section 1.

In addition, the positive electrode cell 1a has a pipe 2 for discharging the electrolyte.
8 are connected. A gas accumulation tank 29 for accumulating gas generated within the system is installed in the middle of the piping 28, and a valve 3 is installed above the gas accumulation tank 29.
6 is provided. Further, the pipe 28 is connected to a pipe 23 branched from the pipe 21 described above via a valve 33.

Further, the pipe 28 is connected to a pipe 27 via a valve 34, and the pipe 27 is branched into a pipe 25 and a pipe 26. Piping 25 is connected to second bag-shaped container 12 within electrolyte tank 13 . Further, one pipe 26 is connected to the above-mentioned pipe 22 via a valve 32.

Hydrochloric acid or the like is used as the electrolytic solution, FeCQ, 2 or the like is used as the positive electrode active material, and CrC 1 or the like is used as the negative electrode active material.

During the charging operation, valve 31 and valve 34 are in an open state, and valve 32 and valve 33 are in a closed state. The electrolytic solution in the first bag-shaped container 11 is passed through the pipes 21, 22, and 24 to the electrode part 1 by the pump 14.
It is supplied to the positive electrode cell 1a inside. At this time, valve 3
No. 3 is in a closed state, so it does not flow into the pipe 23. After the electrode reaction, the electrolytic solution is discharged from the pipe 28, passes through the valve 34, the pipe 27, and the pipe 25, and is delivered into the second bag-like container 12. At this time, since the valves 33 and 32 are closed, the electrolyte does not flow into the pipes 23 and 26. In this way, the electrolytic solution in the first bag-like container 11 moves into the second bag-like container 12 through the inside of the positive electrode cell 1a.

During the discharging operation, the valves 31 and 34 are closed, and the valves 32 and 33 are opened, contrary to the charging operation. The electrolyte in the second bag-like container 12 is pumped through the pipe 25, the pipe 26, and the valve 3 by the pump 14.
2 and piping 24, and is supplied into the positive electrode cell la of the electrode section 1.

At this time, since the valve 31 is in the closed state, the electrolyte in the second bag-like container 12 does not flow into the pipe 21, and the electrolyte in the first bag-like container 11 does not flow out into the pipe 21.

The electrolytic solution supplied into the positive electrode cell la is discharged from the pipe 28 after an electrode reaction with the positive electrode 3. The discharged electrolyte passes through the piping 23, the valve 33, and the piping 21, and is sent into the first bag-shaped container 11. At this time, since the valve 34 is in a closed state, the electrolytic solution does not flow out into the pipe 27. In this way, during the discharge operation, the electrolytic solution in the second bag-like container 12 is supplied into the positive electrode cell 1a and the first
into the bag-like container 11.

In the above charging/discharging operation, when gas is generated within the electrode section 1 due to a side reaction, this gas passes through the pipe 28 and is stored in the gas storage tank 29. This gas is transferred to valve 36
When opened, it is discharged to the outside.

In the redox flow battery of this example, the electrolytic solution supplied to the electrode section and the electrolytic solution discharged from the electrode section are both stored in the electrolytic solution tank.
Since they are stored separately in the first bag-like container and the second bag-like container, they do not mix with each other. Therefore, like the conventional four-tank redox flow battery, it is possible to supply an electrolytic solution whose active material concentration is always constant during charging and discharging operations.

Furthermore, since the first bag-like container and the second bag-like container are in a relationship such that when one becomes larger, the other becomes smaller, the combined size of both is always constant and can accommodate the entire amount of electrolyte. It can be housed in a large electrolyte tank. Therefore, compared to the conventional four-tank type, the size of the tank can be approximately halved, and miniaturization can be achieved.

Furthermore, since the capacity of the first bag-like container and the second bag-like container changes depending on the amount of electrolyte stored therein, there is no need to provide a space inside each container. Can be filled with electrolyte. In addition, by providing a gas storage tank at an appropriate location as in this example, it is possible to discharge the gas generated by side reactions into this gas storage tank and fill the entire electrolyte distribution system with electrolyte. become.

Furthermore, even if the volume of the electrolyte changes due to a change in temperature, the first bag-like container and the second bag-like container each have flexibility, so that they can be adjusted according to the change in the volume of the electrolyte. The size increases and decreases respectively. Therefore, the pressure applied to the piping can be removed.

Although the electrode part is shown in a simplified manner in FIG. 1, a multi-stage connection type electrode part composed of a stack of positive electrode plates, negative electrode plates, diaphragms, bipolar plates, etc. can also be used in the present invention. Needless to say, it can be done.

The materials of the first bag-like container and the second bag-like container are as follows:
Although rubber woven fabric is used as an example, the material is not particularly limited as long as it is flexible enough to change its volume depending on the amount of electrolyte stored.

Further, the present invention can be applied to a one-component redox flow battery that uses an electrolyte containing both a positive electrode active material and a negative electrode active material as the positive electrode solution and the negative electrode solution.

Further, in the electrolyte flow type secondary battery of the present invention, when the electrolyte is injected in a state where the first bag-like container and the second bag-like container are not filled with the electrolyte, air is not mixed in. Can be injected without

In other words, conventionally, when injecting electrolyte into an electrolyte tank, in order to avoid air intrusion, the inside of the electrolyte tank is kept in a vacuum state, or after the electrolyte is injected, it is evacuated and an inert gas is injected. Gas was injected to expel the air while electrolyte was injected. However, with these methods, it is difficult to completely exclude air, and there are structural problems such as the need to create a vacuum state.

In contrast, in the electrolyte flow type secondary battery of the present invention, both the first bag-like container and the second bag-like container in which the electrolyte is stored have a capacity that changes depending on the amount of the electrolyte. Due to their flexibility, the electrolyte can be injected without mixing air by completely eliminating the air inside these containers to reduce the volume inside the container to zero, and then injecting the electrolyte. be able to.

[Effects of the Invention] As explained above, the electrolyte flow type secondary battery of the present invention can reduce the size of the electrolyte tank by almost half compared to the conventional four-tank type battery. This makes it possible to downsize the entire device.

In addition, stable charging and discharging can be performed by supplying an electrolytic solution with a constant concentration of active material, and the battery voltage can be kept constant, which facilitates battery input/output control.

Furthermore, as explained in the embodiment, gas within the piping system can be completely shut off. Further, even if the volume of the electrolytic solution changes due to temperature changes, it is possible to prevent pressure from being applied to the piping system.

Although the embodiments have been described using a redox flow battery as an example, the present invention can also be applied to other secondary batteries that are charged and discharged by flowing an electrolyte.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing a conventional four-tank redox flow battery. In the figure, 1 is an electrode part, 11 is a first bag-shaped container, and 12
indicates a second bag-like container, and 13 indicates an electrolyte tank. Figure 2

Claims (4)

[Claims] (1) By supplying the electrolytic solution from the electrolytic solution tank to the electrode section and returning the electrolytic solution discharged after the reaction at the electrode section to the electrolytic solution tank, the electrolytic solution is circulated within the electrode section for charging and discharging. An electrolyte flow type secondary battery, wherein the electrolyte tank includes a first bag-shaped container having flexibility whose volume changes depending on the amount of electrolyte stored therein, and a second bag-shaped container having flexibility. When charging, the electrolyte in the first bag-like container is supplied to the electrode section, and after the reaction returns to the electrolyte tank and is stored in the second bag-like container. When discharging, the electrolyte in the second bag-like container is supplied to the electrode part, and after the reaction returns to the electrolyte tank and is stored in the first bag-like container. Electrolyte flow type secondary battery. (2) An inert gas is filled between the inner wall of the electrolyte tank and the outer walls of the first bag-like container and the second bag-like container. Range 1
Electrolyte flow type secondary battery as described in . (3) The electrolyte flow type secondary battery according to claim 2, wherein the inert gas is nitrogen gas. (4) The electrolyte flow type secondary battery according to claim 1, 2 or 3, wherein the electrolyte flow type secondary battery is a redox flow battery.