JP3193992B2 - Electrolyte flow battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolyte-flow battery, and more particularly to a pump for maintaining a high level of current efficiency by appropriately changing the number of battery stacks used for charging and discharging, and for circulating an electrolyte. The present invention relates to an electrolyte-flowing battery with reduced power and improved system efficiency.

[0002]

2. Description of the Related Art A redox flow battery will be described as an example of a conventional electrolyte flow battery. FIG. 7 shows a cell structure of a redox flow battery. As shown in the figure, a redox flow battery has an electrolyte flowing type electrolytic cell 100 having a positive electrode chamber 100a and a negative electrode chamber 100b separated by a diaphragm 100c, a positive electrode electrolyte tank 101, a negative electrode electrolyte tank 102, and a positive electrode electrolyte. It comprises a pump 103 for supplying the chamber 100a, a pump 104 for supplying the negative electrode electrolyte to the negative electrode chamber 100b, and a pipe connecting them. The positive electrode chamber 100a has a positive electrode 100d and a negative electrode chamber 100d.
b is provided with a negative electrode 100e.

An iron-chromium battery using a chromium chloride solution and an iron chloride solution as electrolytes will be described as an example. An iron ion hydrochloric acid solution is stored in the cathode electrolyte tank 101, and the solution is circulated between the cathode chamber 100 a and the cathode electrolyte tank 101 by the pump 103. A chromium ion hydrochloric acid solution is stored in the anode electrolyte tank 102, and the solution is circulated between the anode chamber 100 b and the anode electrolyte tank 102 by the pump 104.

In the redox flow battery having the above structure, when a voltage is applied between the positive electrode 100d and the negative electrode 100e to perform charging, the positive electrode chamber 100a In this state, electric energy is stored. In the case of discharging, the opposite reaction occurs and electric power can be taken out.

In the redox flow type battery, charging or discharging proceeds as the composition of the electrolytic solution changes as described above, and the electrodes in each cell do not change. It is possible to change the number of cells to be used according to. JP-A-61-193375 and
The technique disclosed in Japanese Patent Application Laid-Open No. 1-146269 utilizes the above-described features of a redox flow battery, provides a trimming terminal on a stacked redox flow battery body, and reduces the number of cells used during a charge / discharge operation. Is switched to perform voltage adjustment.

[0006]

However, in this conventional method, although it is possible to adjust the redox flow battery voltage, the current efficiency is reduced due to the generation of unused cells during operation, and furthermore, the unused cells are reduced. However, there is a problem that the system efficiency is reduced due to an increase in the pump power for supplying the electrolyte. That is, when the number of cells to be used is switched during charging or discharging, if the electrolyte is continuously supplied to the unused cells, the self-discharge of the electrolyte proceeds on the electrode in the cell, and the current efficiency is reduced. In addition, since unnecessary electrolytic solution is supplied to the unused cells, the loss of pump power is also increased (see FIG. 2). In particular, in a large-scale system in which a plurality of battery cells are set, there is a problem that the above-described influence is increased and the system efficiency including pump power is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in consideration of the above-described problems, and has been made in consideration of the above problems, and has been described in a battery system including a plurality of battery stacks (a plurality of battery cells stacked). When necessary, the electric circuit connection switch and the electrolytic valve for supplying the electrolytic solution can be appropriately switched to prevent a decrease in the current efficiency of the electrolytic cell type battery and to reduce the power consumption of the pump. An object of the present invention is to provide an electrolyte-flowing battery with improved system efficiency including power.

[0008]

According to a first aspect of the present invention, there is provided a battery stack comprising a plurality of battery cells each comprising a positive electrode chamber and a negative electrode chamber separated by a diaphragm. And an electrolyte flow type battery having pumps 9 and 10 for circulating an electrolyte in each of the electrode chambers, as shown in FIG. Valves 1a-6a, 1b-6b, 1c-6
c, 1d to 6d, and each of the battery stacks 1 to 6
Are connected in series, and the output of each connection is connected to a circuit switch 1f.
-6f to the output terminal 12 to control the circulation of the electrolytic solution by controlling the opening and closing of the electric valve, and to control the output terminal 12 by controlling the opening and closing of the electric circuit switch.
Is provided with a control unit 11 for controlling the voltage.

Further, in the invention according to a second aspect, the control section is configured to open and close the electric circuit so that the current efficiency and the system efficiency of the electrolyte flowing type battery are optimized according to the electric characteristics or the load characteristics of the charging power supply. Vessels 1f to 6f and electric valves 1a to
6a, 1b to 6b, 1c to 6c, and 1d to 6d can be controlled to open and close.

In a third aspect of the present invention, the power supply for charging is a solar cell, and the control unit controls the electric circuit switch and the electric valve so that the power generation efficiency is optimized according to the electric characteristics of the solar cell. It is characterized by performing opening and closing control.

[0011]

According to the present invention, by adopting the above-mentioned structure, the redox flow battery is characterized in that at the time of charging and discharging, only the composition of the electrolytic solution changes as described above, and the electrode itself inside the battery does not change at all. And Therefore, the battery stacks 1 to 6 used during charging or discharging can be arbitrarily selected. For example, the battery stacks 1 to 6 are used to charge an electrolyte-flowing type battery, and at the time of discharging, an operation pattern in which only the battery stacks 1 to 4 are used becomes possible. In other words, only the electric circuit switch 6f should be closed (connected state) during charging, and only 4f should be closed during discharging.

Further, if the supply of the electrolyte is continued to the battery stack not involved in the charge or the discharge, the extra pump power is consumed (see FIG. 2), so that the overall system efficiency is reduced and the electrode inside the battery is reduced. Therefore, the self-discharge of the electrolytic solution easily proceeds and the current efficiency is reduced. However, by providing electric valves in the electrolytic solution inlet and outlet pipes of each of the battery stacks 1 to 6, for the battery stacks not used, By closing the electric valve and stopping the supply of the electrolyte, the control unit 11 can prevent the efficiency from decreasing.

Further, the output of each of the battery stacks 1 to 6 is connected in series, and the output of each connection portion is led to the output terminal 12 through the circuit switches 1f to 6f, so that the overall battery voltage can be reduced. Since the electric circuit switches 1f to 6f can be adjusted by opening and closing, for example, as described later, power generation efficiency can be increased by adjusting to electric characteristics of a solar cell or the like. Further, the output voltage can be set according to the load demand.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of the electrolyte-flowing battery of the present invention. As shown in the figure, the electrolyte-flow-type battery of the present invention has a plurality of battery stacks (six in this figure) 1 to 6, and the electrolyte supplied to the negative electrode chambers of each of the battery stacks 1 to 6 is a negative electrode tank. The electric valves 1c to control the flow of the electrolyte are provided at the inlet and the outlet of each of the battery stacks 1 to 6.
6c, 1d to 6d are provided. Each battery stack 1
Electrolytes supplied to the positive electrode chambers of Nos. 1 to 6 are stored in a positive electrode solution tank 8 and are piped so as to be circulated by a pump 10. Further, the flow of the electrolyte is controlled at the inlet and outlet of each of the battery stacks 1 to 6. Electric valves 1a to 6a, 1b to 6b are provided.

Outputs of the respective battery stacks 1 to 6 are connected in series, and a connection portion of each of the battery stacks 1 to 6 is connected to an output terminal 12 via electric circuit switches 1f to 6f. The control unit 11 closes only one of the specified circuit switches 1f to 6f according to the output voltage or the charging voltage, and the control unit 11 further controls the positive side of the battery stack corresponding to the closed circuit switch, For example, when the electric circuit switch 4f is closed, the electric valves 5a, 6a, 5b, 6
b, 5c, 6c, 5d, and 6d are controlled to be closed.

FIG. 3 shows an application example of an electrolyte flowing battery.
Here, a case is shown in which the electric power generated by the solar cell 30 is supplied to the load 32 and stored in the electrolyte flowing battery 31. Generally, a solar cell has an IV characteristic (current-voltage characteristic) and a power characteristic (power-voltage characteristic) shown in FIG. Therefore, the power generation characteristics of the solar cell are determined from these characteristics. That is, the maximum generated power is obtained at the point of the voltage VSm in FIG. Therefore, the electrolyte flowing type battery 3
If the battery voltage of No. 1 can be set to this VSm, the power generated by the solar cell 30 can be efficiently stored (charged) in the electrolyte flowing type battery. That is, in FIG. 1, the control unit 11 selects and closes one of the circuit switches 1f to 6f so that the voltage of the output terminal 12 matches this VSm, and controls the electric valve of the battery stack not used for charging. Close.

On the other hand, in the electrolyte-flowing type battery, the battery voltage changes depending on the state of charge of the electrolyte. FIG. 5 shows a voltage-charging depth characteristic showing a relationship between a battery voltage per one stack and a charging depth. As shown in the figure, the battery voltage per stack is VRa, according to the charging depth Ta, Tb, Tc.
It changes to VRb and VRc. Since the battery voltage of the entire electrolyte circulating battery is determined by the number of battery stacks connected in series according to the charging depth T, by multiplying each of the voltages VRa to VRc by the number of battery stacks, the overall battery voltage is reduced. I get it.

Therefore, in order to set the voltage of the electrolyte flowing type battery to VSm shown in FIG. 4, VSm = VRa
The number of stacks Na to Nc may be determined according to the change of one stack voltage so that × Na to VSm = VRc × Nc. The control unit 11 obtains the number of stacks N such that the entire battery voltage becomes equal to VSm according to the current charging depth, closes the corresponding electric circuit switch, and closes the electric valve of the unused battery stack. By doing so, it is possible to efficiently store the power generated by the solar cell.

FIG. 6 shows an example of the load demand pattern. Various patterns can be considered for the load demand. For example, a case as shown in FIG. 6 can be assumed as an example of the load demand pattern. The required power demand has five stages (L1 to L
5) It can be roughly classified. Therefore, if the control unit 11 adjusts the number of used battery stacks of the electrolyte circulating battery as described above in accordance with the demand level, stable power can be supplied while maintaining the system efficiency of the electrolyte circulating battery. .

[0020]

As described above, according to the present invention, the following excellent effects are expected. (1) Since the supply of the electrolytic solution to the unused battery stack is stopped by providing an electric valve, a high level of current efficiency is maintained, and the power consumption of the pump power is reduced and the system efficiency is improved.

(2) Since the battery voltage of the electrolyte-flowing type battery can be adjusted, the generated power of the solar cell or the like can always be used to the maximum.

[Brief description of the drawings]

FIG. 1 is a view showing a configuration of an electrolyte flowing battery according to the present invention.

FIG. 2 is a diagram showing pump power when the number of used stacks differs between charging and discharging.

FIG. 3 is a diagram showing an application example of an electrolyte flowing battery.

FIG. 4 is a diagram showing characteristics of a solar cell.

FIG. 5 is a diagram showing a charging depth and a voltage characteristic per one stack.

FIG. 6 is a diagram showing an example of a load demand pattern.

FIG. 7 is a view showing a structure of a cell of a redox flow battery.

[Explanation of symbols]

 1-6 Battery stack 1a-6a Electric valve 1b-6b Electric valve 1c-6c Electric valve 1d-6d Electric valve 1f-6f Electric circuit switch 7 Negative liquid tank 8 Positive liquid tank 9 Pump 10 Pump 11 Control unit 12 Output terminal

──────────────────────────────────────────────────続 き Continuing on the front page (72) Izumi Tsuda 1-1-4 Umezono, Tsukuba, Ibaraki Pref. Inside the Research Institute of Electronics and Technology (72) Inventor Yutaka Wada 11-1 Haneda Asahimachi, Ota-ku, Tokyo No. EBARA CORPORATION (72) Inventor Yuichi Akai 11-1 Haneda Asahimachi, Ota-ku, Tokyo Investigator, EBARA CORPORATION Examiner Yasuharu Takagi (56) References JP-A-6-44996 (JP, A (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01M ^8/ 18-8/20

Claims (3)

(57) [Claims] 1. An electrolyte distribution system comprising: a plurality of battery stacks each including a stack of battery cells each including a positive electrode chamber and a negative electrode chamber separated by a diaphragm; and a pump for circulating an electrolyte through the positive electrode chamber and the negative electrode chamber. In the type battery, an automatic valve is provided in a tube of an electrolyte inflow port and an outflow port of each of the battery stacks, an output of each of the battery stacks is connected in series, and an output of each connection portion is output via a circuit switch. A control unit that controls the circulation of the electrolyte by controlling the opening and closing of the automatic valve and controls the voltage of the output terminal by controlling the opening and closing of the electric circuit switch. Electrolyte flow type battery. 2. The control section controls opening and closing of the electric circuit switch and the automatic valve so that the battery efficiency and the system efficiency of the electrolyte flow type battery are optimized according to the electric characteristics or load characteristics of a charging power supply. The electrolyte flowing type battery according to claim 1, wherein 3. The power supply for charging is a solar cell, and the control unit controls the voltage control by the electric circuit switch and the open / close control of the automatic valve so that the power generation efficiency is maximized in accordance with the electric characteristics of the solar cell. The electrolyte-flow-type battery according to claim 2, wherein: