JPH0815093B2 - Electrolyte circulation type secondary battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrolytic solution circulating secondary battery in which an electrolytic solution is supplied to a positive electrode side and a negative electrode side to charge and discharge the electrolytic solution.

[Prior Art] As an electrolyte circulating secondary battery, for example, a redox flow battery is known. FIG. 5 shows a schematic configuration diagram of a conventional redox flow battery. In FIG. 5, a positive electrode 3 and a negative electrode 4 are provided in the reaction cell 1, and a diaphragm 2 is provided between the positive electrode 3 and the negative electrode 4. By the diaphragm 2, the reaction cell 1 is divided into a positive electrode side 1a and a negative electrode side 1b. An electrolytic solution tank 9 is connected to the positive electrode side 1a via a pipe 5 and a pipe 7. A supply pump 11 is attached to the pipe 7, and a gas venting portion 13 for venting gas generated in the electrolytic solution is attached to the pipe 5. An inert gas introducing pipe 15 for purging is provided above the electrolytic solution tank 9. The inert gas introducing pipe 15 is connected to an inert gas tank (not shown). Conventionally, nitrogen gas or the like has been used as the inert gas. Also on the negative electrode side 1b, it is configured in the same manner as the positive electrode side 1a, the electrolytic solution tank 10, the pipe 6,
It is connected to the negative electrode side 1b via 8. A supply pump 12 is attached to the pipe 8 and a gas vent 14 is attached to the pipe 6. Further, an inert gas introducing pipe 16 is also provided above the electrolytic solution tank 10.

The flow of the electrolytic solution during charging and discharging will be described on the positive electrode side. The electrolytic solution in the electrolytic solution tank 9 is supplied to the positive electrode side 1a of the reaction cell 1 through the pipe 7 by the supply pump 11. After the electrode reaction, the supplied electrolytic solution is returned to the electrolytic solution tank 9 through the pipe 5. The gas generated by the side reaction in the reaction cell is stored above the gas vent 13,
It is released appropriately. An inert gas is introduced at a predetermined pressure into an inert gas introducing pipe attached above the electrolytic solution tank.

In the charge / discharge state, the reaction cell 1 and the supply pumps 11 and 12
A pressure equal to the supply pressure of the supply pumps 11 and 12 is applied to the electrolytic solution in the pipe portion between and. A pressure substantially equal to the gas pressure of the inert gas that pressurizes the electrolytic solution in the battery is applied to the electrolytic solution in the pipes 5 and 6. The electrolytic solution in the reaction cell 1 is flowing in the reaction cell 1 due to this difference in liquid pressure.

[Problems to be Solved by the Invention] By the way, in the conventional redox flow battery, a difference occurs in the liquid pressure of the electrolytic solution between the positive electrode side and the negative electrode side. Therefore, there is a problem in that the ionic active material that contributes to the electrode reaction moves through the diaphragm and the composition of the electrolytic solution becomes unbalanced. As the balance of the composition of the electrolyte is lost,
It has been unavoidable to reduce the charge / discharge efficiency of the entire battery and the battery capacity. If there is an extreme difference in hydraulic pressure,
There was a risk that the diaphragm would be abnormally pressed and damaged. Also,
When the diaphragm bends to one side, the passage of the electrolytic solution flowing in the reaction cell is closed, so that the electrode reaction is not sufficiently performed and the battery efficiency is lowered.

The difference in hydraulic pressure between the positive electrode side and the negative electrode side is caused by one of the pressure difference between the positive gas side and the negative electrode side inert gas or the pressure difference between the supply pumps, which is caused by the shape of the pipe or the degree of valve opening. it is conceivable that. It is also considered that changes in the viscosity of the electrolytic solution due to changes in the charging / discharging state and changes in temperature are also involved.

An object of the present invention is to provide an electrolytic solution circulation type secondary battery in which the charge and discharge efficiency of the entire battery is improved and the battery capacity is not reduced by making the pressure of the electrolytic solution equal on the positive electrode side and the negative electrode side. is there.

[Means and Actions for Solving Problems] In the electrolytic solution circulating secondary battery according to claim 1, a diaphragm is provided between the positive electrode and the negative electrode so that the inside of the reaction cell is on the positive electrode side and the negative electrode side. In an electrolytic solution circulation type secondary battery in which the electrolytic solution is separately charged and discharged to the positive electrode side and the negative electrode side,
The pressure of the electrolytic solution on the positive electrode side and the pressure of the electrolytic solution on the negative electrode side during the operation of the battery, respectively, in response to the measurement result by the measuring means and the measurement result by the measuring means, Liquid pressure control means for equalizing the pressure and the pressure of the electrolytic solution on the negative electrode side are provided.

The electrolytic solution circulating secondary battery according to claim 2 is the supply pump according to the invention of claim 1, wherein the hydraulic pressure control means supplies the electrolytic solution in response to the measurement result by the measuring means. It is characterized by including a supply pump control means for controlling the.

In the electrolytic solution circulating secondary battery according to claim 3, in the invention according to claim 1, the liquid pressure control means prevents air from being mixed into the electrolytic solution in response to the measurement result by the measuring means. It is characterized by including gas pressure adjusting means for adjusting the gas pressure of the inert gas introduced for purging.

The electrolytic solution circulation type secondary battery according to claim 4 is the supply pump for supplying the electrolytic solution in the invention according to claim 1, wherein the hydraulic pressure control means supplies the electrolytic solution in response to the measurement result by the measuring means. And a gas pressure adjusting means for adjusting the gas pressure of the inert gas introduced for purging so that air is not mixed into the electrolytic solution in response to the measurement result by the measuring means. It is characterized by including things.

In the electrolytic solution circulating secondary battery according to claim 5, in the invention according to claim 2 or 4, the supply pump control means controls the supply pressure by changing the output frequency of the inverter. It is characterized by that.

In the electrolytic solution circulating secondary battery according to claim 6, in the invention according to claim 3 or 4, the gas pressure adjusting means releases the introduction valve for introducing the inert gas and the inert gas. The feature is that the gas pressure is adjusted by the release valve.

The electrolytic solution circulation type secondary battery according to claim 7 is the invention according to any one of claims 1 to 6, wherein the liquid pressure control means comprises a positive electrode side electrolytic solution pressure and a negative electrode side electrolysis. The feature is that the pressure of the liquid is controlled to a common set value.

The electrolytic solution circulation type secondary battery according to claim 8 is the electrolytic solution circulating type secondary battery according to any one of the inventions according to any one of claims 1 to 6, wherein the hydraulic pressure control means is one of the electrolytic solution on the positive electrode side and the negative electrode side. Is controlled to the value of the pressure of the other electrolytic solution.

The electrolytic solution circulating secondary battery according to claim 9 is characterized in that, in the invention of any one of claims 1 to 8, the electrolytic solution circulating secondary battery is a redox flow type battery. There is.

[Embodiment] FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention. In FIG. 1, a pressure gauge 23 for detecting the pressure of the electrolytic solution in the pipe is attached to the pipe 5 connecting between the positive electrode side 1a and the electrolytic solution tank 9. Also,
Inert gas introduction pipe mounted above the electrolytic solution tank 9
The valve 15 is provided with an introduction valve 25, a branch pipe 27a is attached below the introduction valve 25, and a discharge valve 27 is provided in the branch pipe 27a. Lead wires from the hydraulic pressure control unit 21 are connected to the introduction valve 25 and the discharge valve 27. In addition, the pressure gauge 23 also includes the liquid pressure control unit.
Leads from 21 are connected. The negative electrode side is also similarly configured, and is provided with a pressure gauge 24, an introduction valve 26, a discharge valve 28, a branch pipe 28a, and a hydraulic pressure control unit 22. Other configurations are similar to those of the conventional redox flow battery shown in FIG.

In the embodiment shown in FIG. 1, by adjusting the pressure of the inert gas used for purging the electrolyte solution in the battery so that air is not mixed, the pressure of the electrolyte solution on the positive electrode side and the electrolyte solution on the negative electrode side are adjusted. It is a type that controls the pressure of. During charging and discharging, the pressures of the electrolyte solutions on the positive electrode side and the negative electrode side are detected by pressure gauges 23 and 24, respectively, and replaced with electric signals. This electric signal is transmitted to the hydraulic pressure control units 21 and 22 by the lead wires and compared with the set value in the hydraulic pressure control units. From the comparison with the set value, it is judged whether the pressure of the electrolyte solution on the positive electrode side and the negative electrode side is smaller or larger than the set pressure, and based on this judgment, a control signal is sent to the introduction valves 25, 26 or the discharge valves 27, 28. . If the electrolyte pressure is less than the set pressure, introduce valve 2
Open 5,26 and introduce an inert gas to increase the pressure of the electrolyte. When the pressure of the electrolytic solution is higher than the set pressure, a control signal is sent to the release valves 27 and 28, and the release valve is opened to release the inert gas to lower the gas pressure and lower the pressure of the electrolytic solution. Let This control is independently performed on the positive electrode side and the negative electrode side. Therefore, by setting the set values of the hydraulic pressure control units 21 and 22 to the same value, the pressure of the electrolytic solution on the positive electrode side and the pressure of the electrolytic solution on the negative electrode side can be made equal.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the present invention. The embodiment of FIG. 2 detects the pressure of the electrolytic solution on the negative electrode side and controls the pressure of the electrolytic solution on the positive electrode side so as to be equal to the pressure of the electrolytic solution on the negative electrode side. Therefore, in the embodiment of FIG. 2, only one hydraulic control unit is used. Hydraulic pressure control unit 31
A lead wire from a pressure gauge 33 on the positive electrode side and a pressure gauge 34 on the negative electrode side is connected to. Further, the lead wire for sending the control signal is connected only to the positive electrode side introduction valve 35 and discharge valve 37.

The pressure of the electrolytic solution on the negative electrode side measured by the pressure gauge 34 is converted into an electric signal and transmitted to the hydraulic pressure control unit 31. Further, the pressure of the electrolyte solution on the positive electrode side measured by the pressure gauge 33 is also converted into an electric signal and transmitted to the hydraulic pressure control unit 31. In the liquid pressure control unit 31, the pressure of the electrolytic solution on the positive electrode side is compared with the pressure of the electrolytic solution on the negative electrode side, and control signals are introduced so that they become equal to the pressure of the electrolytic solution on the negative electrode side. Sent to. If the pressure of the electrolyte solution on the positive electrode side is lower than the pressure of the electrolyte solution on the negative electrode side, the introduction valve 35 is opened, and the inert gas is introduced and pressurized, whereby the pressure of the electrolyte solution on the positive electrode side is increased. Is increased. When the pressure of the electrolyte solution on the positive electrode side is higher than the pressure of the electrolyte solution on the negative electrode side, the release valve 37 is opened and the inert gas is released, so that the pressure of the electrolyte solution on the positive electrode side is increased. Can be lowered. In this way, the pressure of the electrolytic solution on the positive electrode side and the pressure of the electrolytic solution on the negative electrode side are controlled to be equal.

FIG. 3 is a schematic configuration diagram showing a third embodiment of the present invention. Pressure gauges 43 and 44 are reaction cells 1 of pipes 7 and 8, respectively.
It is attached in the vicinity. Inverters 45 and 46 are attached to the supply pumps 11 and 12, respectively, and lead wires for giving control signals from the hydraulic pressure control units 41 and 42 are connected to the inverters 45 and 46, respectively. Further, the hydraulic pressure control units 41 and 42 are connected with lead wires for receiving measurement signals from the pressure gauges 43 and 44, respectively. Other configurations are almost the same as those of the conventional redox flow battery shown in FIG.

During the charging / discharging operation, the pressures of the electrolyte solutions on the positive electrode side and the negative electrode side are respectively detected by the pressure gauges 43, 44, converted into electric signals and transmitted to the hydraulic pressure control units 41, 42. In the hydraulic pressure control units 41, 42, the sent measurement signal is compared with the measured value to determine whether the measured pressure of the electrolytic solution is higher than the set pressure. Based on this judgment, the control signal is changed to the hydraulic pressure control unit 4
1, 42 are transmitted to the inverters 45, 46, respectively. If the pressure of the electrolytic solution is lower than the set pressure, the output frequency of the inverter is increased and the rotation speed of the supply pump is increased to increase the pressure of the electrolytic solution. If the electrolyte pressure is higher than the set pressure, lower the output frequency of the inverter and reduce the rotation speed of the supply pump.
Reduce the electrolyte pressure. Such control is independently performed on the positive electrode side and the negative electrode side. Therefore, by setting the set values in the positive and negative liquid pressure control units to the same value, the pressure of the electrolyte on the positive electrode side and the pressure of the electrolyte on the negative electrode side can be made equal.

FIG. 4 is a schematic configuration diagram showing a fourth embodiment of the present invention. In the embodiment shown in FIG. 4, the pressure of the electrolytic solution on the negative electrode side is detected, and the pressure of the electrolytic solution on the positive electrode side is controlled to be equal to the pressure of the electrolytic solution on the negative electrode side. Therefore,
Only one hydraulic control unit is provided.
The hydraulic pressure control unit 51 is provided with a lead wire for transmitting a detection signal of the pressure gauges 53, 54, and a lead wire for sending a control signal from the hydraulic pressure control unit 51 is connected to the inverter 55. Has been done. A connection line for transmitting an output frequency from the inverter 55 to the supply pump 11 is attached. A control signal is not sent to the negative side inverter 56, and a connection line for transmitting the output frequency from the inverter 56 is attached to the pump 12.

During charging and discharging, the pressure of the electrolyte solution on the positive electrode side and the negative electrode side is
It is detected by pressure gauges 53 and 54, respectively. The detected pressure is converted into an electric signal, and the hydraulic pressure control unit 51
Be transmitted to. In the liquid pressure control unit 51, the pressure of the electrolytic solution on the positive electrode side is compared with the pressure of the electrolytic solution on the negative electrode side,
A control signal is transmitted to the inverter 55 so as to equalize the pressure of the electrolytic solution on the negative electrode side. In the inverter 55, the output frequency is changed according to the control signal to change the rotation speed of the supply pump 11. If the pressure of the electrolytic solution on the positive electrode side is lower than the pressure of the electrolytic solution on the negative electrode side, the output frequency of the inverter 55 is increased, the rotation speed of the supply pump 11 is increased, and the pressure of the electrolytic solution on the positive electrode side is increased. Increase. When the pressure of the electrolyte on the positive electrode side is higher than the pressure of the electrolyte on the negative electrode side, the output frequency of the inverter 55 is reduced to reduce the rotation speed of the supply pump 11, and the pressure of the electrolyte on the positive electrode side is reduced. Let In this embodiment, the pressure of the electrolytic solution on the negative electrode side is thus detected, and the pressure of the electrolytic solution on the positive electrode side is controlled to be equal to the pressure of the electrolytic solution on the negative electrode side.

In the examples of FIGS. 2 and 4, the pressure of the electrolytic solution on the positive electrode side is controlled to be equal to the pressure of the electrolytic solution on the negative electrode side. It may be controlled to be equal to the pressure of the electrolytic solution.

[Effects of the Invention] As described above, in the electrolytic solution circulation type secondary battery of the present invention, the pressure of the electrolytic solution on the positive electrode side and the pressure of the electrolytic solution on the negative electrode side are made equal by the hydraulic pressure control means. There is no difference in the pressure of the electrolytic solution between the negative electrode and the negative electrode. Therefore, it is possible to effectively prevent the movement of the ionic active material through the diaphragm and the breakage of the diaphragm, which are problems in the conventional electrolyte circulating secondary battery. Further, the charge / discharge efficiency of the battery as a whole is improved, and the decrease in battery capacity can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing a second embodiment of the present invention. FIG. 3 is a schematic configuration diagram showing a third embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing a fourth embodiment of the present invention. FIG. 5 is a schematic configuration diagram of a conventional redox flow battery. In the figure, 1 is a reaction cell, 1a is a positive electrode side, 1b is a negative electrode side,
2 is a diaphragm, 3 is a positive electrode, 4 is a negative electrode, 5,6,7,8 are pipes, 9,10
Is an electrolytic solution tank, 11 and 12 are supply pumps, 15 and 16 are inert gas introducing pipes, 21 and 22 are hydraulic pressure control units, 23 and 24 are pressure gauges, 25 and 26 are introducing valves, and 27 and 28 are discharging. The valve is shown.

Claims (9)

[Claims] 1. An electrolytic solution circulating secondary battery in which a diaphragm is provided between a positive electrode and a negative electrode to divide the inside of the reaction cell into a positive electrode side and a negative electrode side, and an electrolytic solution is supplied to each of the positive electrode side and the negative electrode side for charging and discharging. In the operation of the battery, the positive electrode side electrolytic solution pressure and the negative electrode side electrolytic solution pressure, respectively, measuring means for continuously measuring, in response to the measurement result by the measuring means, the positive electrode And a liquid pressure control means for equalizing the pressure of the electrolyte solution on the side of the negative electrode and the pressure of the electrolyte solution on the side of the negative electrode. 2. The liquid pressure control means includes supply pump control means for controlling a supply pump for supplying an electrolytic solution in response to a measurement result by the measuring means. An electrolyte circulating secondary battery according to item 1. 3. A gas pressure adjusting means for adjusting the gas pressure of an inert gas introduced for purging air so that air is not mixed into the electrolytic solution in response to the measurement result by the measuring means. The electrolytic solution circulating secondary battery according to claim 1, comprising: 4. The supply pressure control means controls a supply pump for supplying an electrolytic solution in response to a measurement result of the measuring means, and a response to a measurement result of the measuring means. 2. A combination of gas pressure adjusting means for adjusting a gas pressure of an inert gas introduced for purging air so as not to mix air into the electrolytic solution. Electrolyte circulation type secondary battery. 5. The electrolytic solution circulation according to claim 2, wherein the supply pump control means controls the supply pressure by changing the output frequency of the inverter. Type secondary battery. 6. The gas pressure adjusting means adjusts the gas pressure by an introduction valve for introducing an inert gas and a release valve for releasing the inert gas. Or the electrolytic solution circulation type secondary battery according to item 4. 7. The liquid pressure control means controls the pressure of the electrolytic solution on the positive electrode side and the pressure of the electrolytic solution on the negative electrode side to a common set value. 7. The electrolytic solution circulating secondary battery according to any one of items 1 to 6. 8. The liquid pressure control means controls the pressure of one of the electrolyte solutions on the positive electrode side and the negative electrode side to the value of the pressure of the other electrolyte solution. Electrolyte circulation type 2 according to any one of ranges 1 to 6
Next battery. 9. The electrolytic solution circulating secondary battery is a redox flow type battery, and the electrolytic solution circulating secondary battery is a redox flow battery.
8. The electrolytic solution circulating secondary battery according to any one of items 8.