Redox flow battery

Abstract

To provide a redox flow battery that reduces a shunt current and that can electrically separate any cell stack in a series circuit while continuing the operation of any other cell stacks.SOLUTION: A redox flow battery comprises at least one series circuit which has at least two cell stacks electrically connected to each other in series. Each of the at least two cell stacks comprises a cell stack input terminal and a cell stack output terminal. For each of the at least two cell stacks, a bypass circuit is provided that electrically bypasses the cell stack. The bypass circuit comprises a bypass circuit input terminal and a bypass circuit output terminal. For one cell stack of the at least two cell stacks, there are provided an input switch for switching between a cell stack input terminal and a bypass circuit input terminal and an output switch for switching between a cell stack output terminal and a bypass circuit output terminal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to redox flow batteries. [Background technology]

[0002] Redox flow batteries are being considered as secondary batteries for energy storage, but to obtain a specified electrical output, cells must be electrically connected in series and parallel. A challenge in this case is that when cells are electrically connected in series, current flows through the electrolyte path along the potential gradient. This current, called shunt current, is unrelated to the charging and discharging of the battery (it is simply leakage current that flows through the electrolyte path and does not contribute to the charging and discharging of the battery), and it causes losses in the battery's charge and discharge efficiency.

[0003] Patent Document 1 discloses a redox flow battery designed to reduce shunt current. This redox flow battery includes a first series circuit and a second series circuit in which a plurality of cell stacks are electrically connected in series, and first and second electrolyte supply and discharge lines for supplying and discharging electrolyte to the cell stacks. The first and second series circuits are electrically connected in parallel, and the first and second electrolyte supply and discharge lines are connected in parallel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2931650 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the conventional configuration shown in Patent Document 1, although it is possible to reduce the shunt current, it is not possible to electrically disconnect any cell stack from the first series circuit or the second series circuit and continue operating the other cell stacks, so maintenance or inspection of any cell stack requires stopping operation of all cell stacks for an extended period of time.Furthermore, because it is not possible to electrically disconnect any cell stack from the first series circuit or the second series circuit and continue operating the other cell stacks, it is not possible to arbitrarily adjust the voltage obtained in the first series circuit or the second series circuit.

[0006] The present disclosure has been made in consideration of the above-described problems, and aims to provide a redox flow battery that reduces shunt current and allows any cell stack to be electrically disconnected from a series circuit while the other cell stacks continue to operate. [Means for solving the problem]

[0007] In order to achieve the above object, the redox flow battery according to the present disclosure comprises: A redox flow battery comprising at least one series circuit in which at least two or more cell stacks each including at least one cell are electrically connected in series, the at least one cell is divided into a first chamber and a second chamber by a diaphragm, a first electrolytic solution flows through the first chamber, and a second electrolytic solution flows through the second chamber; a first flow path including the first chamber in a path through which the first electrolytic solution flows, and a second flow path including the second chamber in a path through which the second electrolytic solution flows, are individually provided in each of the at least two or more cell stacks; each of the at least two or more cell stacks includes a cell stack input terminal and a cell stack output terminal; a bypass circuit that electrically bypasses the cell stack is provided for each of the at least two or more cell stacks; each of the bypass circuits includes a bypass circuit input terminal and a bypass circuit output terminal; For each of the at least two or more cell stacks, an input switch for switching between the cell stack input terminal and the bypass circuit input terminal, and an output switch for switching between the cell stack output terminal and the bypass circuit output terminal are provided. 、 the at least one series circuit includes at least two or more series circuits electrically connected in parallel; a connection circuit electrically connecting the at least two series circuits in parallel, Between the connection circuit and each of the at least two or more series circuits, there are provided a first diode that allows a current to flow only from the connection circuit to the series circuit, a second diode that allows a current to flow only from the series circuit to the connection circuit, and a changeover switch that connects the connection circuit to either the first diode or the second diode. do. [Effects of the Invention]

[0008] The redox flow battery according to the present disclosure reduces the shunt current and allows any cell stack to be electrically disconnected from the series circuit while the other cell stacks continue to operate. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a configuration example of a redox flow battery according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram illustrating a state in which an arbitrary cell stack is disconnected from the series circuit in the configuration example of the redox flow battery shown in FIG. [Figure 3] FIG. 1 is a schematic diagram showing a configuration example of a redox flow battery according to a second embodiment. [Figure 4] FIG. 10 is a schematic diagram showing an example of the configuration of a cell stack that constitutes a redox flow battery according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a redox flow battery according to an embodiment will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as an embodiment or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0011] [Embodiment 1] FIG. 1 is a schematic diagram showing a configuration example of a redox flow battery 1A according to the first embodiment. As shown in FIG. 1 , the redox flow battery 1A according to the first embodiment is a redox flow battery including one series circuit 2 in which three cell stacks 4, each including one cell 3, are electrically connected in series. While FIG. 1 illustrates the cell stack 4 including one cell 3, the cell stack 4 is not limited to being composed of one cell 3 and may be composed of two or more cells 3. While FIG. 1 illustrates the series circuit 2 in which three cell stacks 4 are electrically connected in series, the cell stack 4 is not limited to being electrically connected in series with three cell stacks 4 and may be composed of any number of cell stacks 4 as long as they are electrically connected in series. Although FIG. 1 illustrates one series circuit 2, the cell stack 4 is not limited to being connected in series with one cell 3 and may be composed of two or more series circuits 2 electrically connected in parallel.

[0012] The cell 3 is divided into a first chamber 31 and a second chamber 32 by a diaphragm 30. A first electrode 33 is disposed in the first chamber 31, and a second electrode 34 is disposed in the second chamber 32. A first electrolytic solution ES1 flows through the first chamber 31, while a second electrolytic solution ES2 flows through the second chamber 32. The first electrode 33 is a positive electrode, and the second electrode 34 is a negative electrode. During charging, a current flows from the first electrode 33 to the second electrode 34, while during discharging, a current flows from the second electrode 34 to the first electrode 33. Thus, during charging, the first electrode 33 becomes an anode and the second electrode 34 becomes a cathode, while during discharging, the first electrode 33 becomes a cathode and the second electrode 34 becomes an anode. The first electrolytic solution ES1 is a positive electrode electrolyte, and is obtained by dissolving an active material in an aqueous solution containing a supporting electrolyte. For example, an acidic aqueous solution in which sulfuric acid is dissolved in an aqueous solution containing a supporting electrolyte is used, and vanadium ions (VO2 + (VO 2+ The second electrolyte solution ES2 is a negative electrode electrolyte, and like the first electrolyte solution ES1, is obtained by dissolving an active material in an aqueous solution containing a supporting electrolyte. For example, an acidic aqueous solution in which sulfuric acid is dissolved in an aqueous solution containing a supporting electrolyte is used, and vanadium ions (V 2+ (V 3+ ) is used.

[0013] In the redox flow battery 1A according to the first embodiment, a first circulation path 41 and a second circulation path 42 are individually provided for each cell stack 4. Thus, one first circulation path 41 and one second circulation path 42 are provided for each of the three cell stacks, for a total of three first circulation paths 41 and three second circulation paths 42. The first circulation path 41 includes the first chamber 31 and is a path through which the first electrolytic solution ES1 flows, while the second circulation path 42 includes the second chamber 32 and is a path through which the second electrolytic solution ES2 flows. The first circulation path 41 and the second circulation path 42 are configured as circulation paths through which the first electrolytic solution ES1 and the second electrolytic solution ES2 circulate, respectively, and the first electrolytic solution ES1 and the second electrolytic solution ES2 are circulated through the first circulation path 41 and the second circulation path 42 by circulation devices 411 and 421 provided in the paths. Although the details of the circulation devices 411 and 421 are not shown, similar to known redox flow batteries, they are composed of a tank for storing an electrolyte and a pump for circulating the electrolyte.

[0014] Each cell stack 4 also includes a cell stack input terminal 43 and a cell stack output terminal 44. The cell stack input terminal 43 is connected to the first electrode 33 (positive electrode), and the cell stack output terminal 44 is connected to the second electrode 34 (negative electrode).

[0015] In the redox flow battery 1A according to the first embodiment, one bypass circuit 5 is provided for one cell stack 4. Therefore, a total of three bypass circuits 5 are provided, one for each of the three cell stacks 4. The bypass circuits 5 are circuits that electrically bypass the cell stacks 4.

[0016] Each bypass circuit 5 includes a bypass circuit input terminal 51 and a bypass circuit output terminal 52. The bypass circuit input terminal 51 corresponds to the cell stack input terminal 43, and the bypass circuit output terminal 52 corresponds to the cell stack output terminal .

[0017] In the redox flow battery 1A according to the first embodiment, one input switch 61 and one output switch 62 are provided for each cell stack 4. Therefore, one input switch 61 and one output switch 62 are provided for each of three cell stacks 4, for a total of three input switches 61 and three output switches 62. The input switch 61 is a switch that switches between the cell stack input terminal 43 and the bypass circuit input terminal 51, and the output switch 62 is a switch that switches between the cell stack output terminal 44 and the bypass circuit output terminal 52.

[0018] When the input switch 61 is switched from the cell stack input terminal 43 to the bypass circuit input terminal 51, the output switch 62 is switched from the cell stack output terminal 44 to the bypass circuit output terminal 52, and when the input switch 61 is switched from the bypass circuit input terminal 51 to the cell stack input terminal 43, the output switch 62 is switched from the bypass circuit output terminal 52 to the cell stack output terminal 44.

[0019] FIG. 2 is a schematic diagram showing a state in which an arbitrary cell stack 4 is disconnected from the series circuit 2 in the configuration example of the redox flow battery 1A shown in FIG. As shown in FIG. 2 , in the redox flow battery 1A according to the first embodiment, an arbitrary cell stack 4 can be electrically disconnected from the series circuit 2 by switching an input switch 61 and an output switch 62 provided for the arbitrary cell stack 4 to a bypass circuit input terminal 51 and a bypass circuit output terminal 52. This forms a series circuit passing through the bypass circuit 5 provided for the arbitrary cell stack 4. Furthermore, by switching an input switch 61 and an output switch 62 provided for the arbitrary cell stack 4 to a cell stack input terminal 43 and a cell stack output terminal 44, the arbitrary cell stack can be electrically restored to the series circuit. This forms a series circuit passing through the arbitrary cell stack 4. In the example shown in FIG. 2 , one cell stack 4 out of three cell stacks 4 is electrically disconnected, but the number of cell stacks 4 to be electrically disconnected is not limited to one, and any number of cell stacks 4 can be disconnected.

[0020] Furthermore, in the redox flow battery 1A according to the first embodiment, any number of cell stacks 4 can be electrically separated, and therefore the voltage obtained by the series circuit 2 can be adjusted by the number of cell stacks 4 to be electrically separated. For example, the voltage (V total ) is V A +V B +V C However, the voltage (V total ) is V A +V C This becomes:

[0021] In the redox flow battery 1A according to the first embodiment, the first circulation path 41 and the second circulation path 42 are individually provided for each cell stack 4. Therefore, even if a potential gradient occurs in three cell stacks 4 electrically connected in series, the shunt current that flows along the potential gradient through the first circulation path 41 or the second circulation path 42 can be reduced. Furthermore, by switching the input switch 61 and output switch 62 provided for any cell stack 4 to the bypass circuit input terminal 51 and bypass circuit output terminal 52, that cell stack 4 can be electrically disconnected from the series circuit 2. This allows the other cell stacks 4 to continue operating. This makes it possible to repair and inspect that cell stack 4 without stopping the operation of all the cell stacks 4 for an extended period of time. Furthermore, since any number of cell stacks 4 can be electrically disconnected from the series circuit 2, the voltage obtained by the series circuit 2 can be adjusted by the number of cell stacks 4 to be disconnected, without using equipment such as a DC / DC converter.

[0022] [Embodiment 2] 3 is a schematic diagram showing a configuration example of a redox flow battery 1B according to Embodiment 2. Note that the same components as those in the redox flow battery 1A according to Embodiment 1 described above are denoted by the same reference numerals, and description thereof will be omitted. As shown in Fig. 3, the redox flow battery 1B according to the second embodiment is a redox flow battery including two series circuits 2 connected electrically in parallel. While Fig. 3 shows the redox flow battery 1B configured with two series circuits 2, the redox flow battery is not limited to one configured with two series circuits 2, and may be one configured with any number of series circuits as long as the series circuits are connected electrically in parallel.

[0023] The redox flow battery 1B according to the second embodiment includes a connection circuit 71 that electrically connects two series circuits 2 in parallel. A first diode 73, a second diode 74, and a selector switch 75 are provided between the connection circuit 71 and each series circuit 2. The first diode 73 and the second diode 74 are arranged in parallel and are both connected to the input switch 61. The first diode 73 allows current to flow only from the connection circuit 71 to the series circuit 2, and the second diode 74 allows current to flow only from the series circuit 2 to the connection circuit 71. The selector switch 75 connects the connection circuit 71 to either the first diode 73 or the second diode 74.

[0024] The changeover switches 75 provided between the connection circuit 71 and each of the series circuits 2 are all connected to the first diode 73 during charging, and are all connected to the second diode 74 during discharging.

[0025] In the redox flow battery 1B according to the second embodiment, during charging, all of the selector switches 75 provided between the connection circuit 71 and each series circuit 2 are connected to the first diode 73, and a current (charging current) flowing from the connection circuit 71 is supplied to the cell stack 4 through the selector switch 75, the first diode 73, the input switch 61, and the cell stack input terminal 43, thereby charging the cell stack 4. Even if a voltage imbalance occurs between the cell stack 4 (4A) and the cell stack 4 (4B) electrically connected in parallel with the cell stack 4A, the first diode 73 allows the current to flow only from the connection circuit 71 to the series circuit 2, preventing the current from flowing from the series circuit 2 into the connection circuit 71. Therefore, electricity charged in the cell stack 4A is not discharged to the cell stack 4B, and electricity charged in the cell stack 4B is not discharged to the cell stack 4A, so that charging and discharging between the cell stack 4A and the cell stack 4B is limited.

[0026] On the other hand, during discharge, all of the changeover switches 75 provided between the connection circuit 71 and each series circuit 2 are connected to the second diode 74, and the current flowing out from the cell stack 4 is supplied to the connection circuit 71 through the input switch 61, the second diode 74, and the changeover switch 75, and is discharged from the cell stack 4. Then, even if a voltage imbalance occurs between the cell stack 4 (4A) and the cell stack 4 (4B) electrically connected in parallel with this cell stack 4A, the second diode 74 allows current to flow only from the series circuit 2 to the connection circuit 71, and prevents current from flowing from the connection circuit 71 into the series circuit 2. Therefore, electricity charged in the cell stack 4A is not discharged to the cell stack 4B, and electricity charged in the cell stack 4B is not discharged to the cell stack 4B, so charging and discharging between the cell stack 4A and the cell stack 4B is limited.

[0027] In the redox flow battery 1B according to the second embodiment, all of the selector switches 75 provided between the connection circuit 71 and each series circuit 2 are connected to the first diode 73 during charging, so that a current (charging current) flows only from the connection circuit 71 to the series circuit 2. This reduces charging and discharging between the two series circuits 2 electrically connected in parallel. During discharging, all of the selector switches 75 provided between the connection circuit 71 and each series circuit 2 are connected to the second diode 74, so that a current (discharging current) flows only from the connection circuit 71 to the series circuit 2. This reduces charging and discharging between the two series circuits 2 electrically connected in parallel.

[0028] [Embodiment 3] 4 is a schematic diagram showing a configuration example of a cell stack 4 constituting a redox flow battery 1C according to Embodiment 3. Note that the same components as those in the redox flow batteries 1A and 1B according to Embodiment 1 and Embodiment 2 described above are denoted by the same reference numerals, and descriptions thereof will be omitted. As shown in Fig. 4, in the redox flow battery 1C according to Embodiment 3, in the redox flow battery 1A according to Embodiment 1 described above or the redox flow battery 1B according to Embodiment 2 described above, one cell stack 4 includes three cells 3. The three cells 3 are electrically connected in parallel. While the figure shows a cell stack 4 in which three cells 3 are electrically connected in parallel, the number of cells is not limited to three, and the cell stack may be composed of any number of cells 3 as long as they are electrically connected in parallel.

[0029] In the redox flow battery 1C according to the third embodiment, the first flow path 41 includes a first supply path 412 and a first recovery path 413. The first supply path 412 is a path that branches off to connect to each of the cells 3 (first chambers 31), and the first recovery path 413 is a path that is connected to each of the cells 3 (first chambers 31). The second flow path 42 includes a second supply path 422 and a second recovery path 423. Similar to the first supply path 412, the second supply path 422 is a path that branches off to connect to each of the cells 3 (second chambers 32), and the second recovery path 423 is a path that is connected to each of the cells 3 (second chambers 32).

[0030] In the redox flow battery 1C according to the third embodiment, a first electrolytic solution ES1 is distributed to the first chambers 31 of the three cells 3, and a second electrolytic solution ES2 is distributed to the second chambers 32 of the three cells 3. Then, the first electrolytic solution ES1 is recovered from the first chambers 31 of the three cells 3, and the second electrolytic solution ES2 is recovered from the second chambers 32 of the three cells 3.

[0031] According to the redox flow battery 1C of the third embodiment, the first electrolytic solution ES1 and the second electrolytic solution ES2 are distributed to each of the three cells 3, and the first electrolytic solution ES1 and the second electrolytic solution ES2 are recovered from each of the three cells 3, so that the potential difference between the three cells 3 electrically connected in parallel can be reduced.

[0032] The present invention is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0033] The contents described in each of the above embodiments can be understood, for example, as follows.

[0034] The redox flow battery (1A) according to the aspect of [1] is A redox flow battery comprising at least one series circuit (2) in which at least two or more cell stacks (4) each including at least one cell (3) are electrically connected in series, The at least one cell (3) is divided into a first chamber (31) and a second chamber (32) by a diaphragm (30), a first electrolytic solution (ES1) flows through the first chamber (31), and a second electrolytic solution (ES2) flows through the second chamber (32), a first flow path (41) including the first chamber (31) in its path and through which the first electrolytic solution (ES1) flows, and a second flow path (42) including the second chamber (32) in its path and through which the second electrolytic solution (ES2) flows are provided individually for each of the at least two or more cell stacks (4); Each of the at least two or more cell stacks (4) includes a cell stack input terminal (43) and a cell stack output terminal (44), a bypass circuit (5) that electrically bypasses the cell stack (4) is provided for each of the at least two or more cell stacks (4); Each of the bypass circuits (5) includes a bypass circuit input terminal (51) and a bypass circuit output terminal (52); For each of the at least two or more cell stacks (4), an input switch (61) is provided for switching between the cell stack input terminal (43) and the bypass circuit input terminal (51), and an output switch (62) is provided for switching between the cell stack output terminal (44) and the bypass circuit output terminal (52).

[0035] According to this configuration, the first flow path (41) and the second flow path (42) are individually provided in each of at least two or more cell stacks (4) electrically connected in series. Therefore, even if a potential gradient occurs in at least two or more cell stacks (4) electrically connected in series, the shunt current that flows along the potential gradient through the first flow path (41) or the second flow path (42) can be reduced. Furthermore, by switching the input switch 61 and output switch 62 provided for any cell stack 4 to the bypass circuit input terminal 51 and the bypass circuit output terminal 52, respectively, the cell stack 4 can be electrically disconnected from the series circuit 2. This allows the other cell stacks 4 to continue operating. This allows repair and inspection of any cell stack 4 without having to stop operation of all the cell stacks 4 for an extended period of time. In addition, any number of cell stacks (4) can be electrically disconnected from the series circuit (2), so the voltage obtained by the series circuit (2) can be adjusted by the number of cell stacks (4) to be disconnected, without using equipment such as a DC / DC converter.

[0036] [2] A redox flow battery (1A) according to another embodiment is the redox flow battery (1A) according to [1], The output switch (62) is switched from the cell stack output terminal (44) to the bypass circuit output terminal (52) when the input switch (61) is switched from the cell stack input terminal (43) to the bypass circuit input terminal (51), and is switched from the bypass circuit output terminal (52) to the cell stack output terminal (44) when the input switch (61) is switched from the bypass circuit input terminal (51) to the cell stack input terminal (43).

[0037] With this configuration, the cell stack 4 corresponding to the input switch 61 can be disconnected simply by switching the input switch 61 from the cell stack input terminal 43 to the bypass circuit input terminal 51. Furthermore, the cell stack 4 corresponding to the input switch 61 can be restored simply by switching the input switch 61 from the bypass circuit input terminal 51 to the cell stack input terminal 43.

[0038] [3] A redox flow battery (1B) according to another embodiment is the redox flow battery (1A) according to [1] or [2], the at least one series circuit (2) includes at least two or more series circuits (2) electrically connected in parallel; a connection circuit (71) that electrically connects the at least two series circuits (2) in parallel, Between the connection circuit (71) and each of the at least two or more series circuits (2), there are provided a first diode (73) that allows current to flow only from the connection circuit (71) to the series circuit (2), a second diode (74) that allows current to flow only from the series circuit (2) to the connection circuit (71), and a changeover switch (75) that connects the connection circuit (71) to either the first diode (73) or the second diode (74).

[0039] According to this configuration, by switching all of the changeover switches (75) provided between the connection circuit (71) and at least two or more series circuits (2) to the first diodes (73), a current (charging current) flows only from the connection circuit (71) to the series circuits (2). This reduces charging and discharging between the series circuits (2) electrically connected in parallel. By switching all of the changeover switches (75) to the second diodes (74), a current (discharging current) flows only from the series circuits (2) to the connection circuit (71). This reduces charging and discharging between the series circuits (2) electrically connected in parallel.

[0040] [4] A redox flow battery (1B) according to another embodiment is the redox flow battery (1B) according to [3], The changeover switch (75) switches to the first diode (73) during charging and switches to the second diode (74) during discharging.

[0041] With this configuration, current flows into the series circuit (2) through the first diode (73) during charging, and current flows out of the series circuit (2) through the second diode (74) during discharging, thereby reducing charging and discharging between the series circuits (2) electrically connected in parallel during charging and discharging.

[0042] [5] A redox flow battery (1C) according to another embodiment is the redox flow battery (1A, 1B) according to any one of [1] to [4], The at least one cell (3) includes at least two or more cells (3) electrically connected in parallel, the first distribution path (41) includes a first supply path (412) branching off to connect to each of the at least two or more cells (3), and a first recovery path (413) connected to each of the at least two or more cells (3); The second distribution path (42) includes a second supply path (422) branching off to each of the at least two or more cells (3), and a second recovery path (423) joining each of the at least two or more cells (3).

[0043] According to this configuration, the first electrolytic solution (ES1) and the second electrolytic solution (ES2) are distributed to each of the at least two or more cells (3), and the first electrolytic solution (ES1) and the second electrolytic solution (ES2) are recovered from each of the at least two or more cells (3), thereby reducing the potential difference between the two or more cells (3) electrically connected in parallel. [Explanation of symbols]

[0044] 1A, 1B, 1C redox flow battery 2 Series Circuit 3 cells 30 Diaphragm 31 Room 1 32 Room 2 33 First electrode (positive electrode) 34 2nd electrode (negative electrode) 4 Cell stack 41 First Distribution Channel 411 Circulation device 412 First Supply Route 413 First Recovery Route 42 Second Distribution Channel 421 Circulation device 422 Second Supply Route 423 Second Recovery Route 43 Cell stack input terminal 44 Cell stack output terminal 5 Bypass circuit 51 Bypass circuit input terminal 52 Bypass circuit output terminal 61 Input switch 62 Output Switch 71 Connection circuit 73 First diode 74 Second diode 75 Changeover switch ES1 1st electrolyte ES2 2nd electrolyte

Claims

1. A redox flow battery comprising at least one series circuit in which at least two or more cell stacks each including at least one cell are electrically connected in series, the at least one cell is divided into a first chamber and a second chamber by a diaphragm, a first electrolytic solution flows through the first chamber, and a second electrolytic solution flows through the second chamber; a first flow path including the first chamber and through which the first electrolytic solution flows, and a second flow path including the second chamber and through which the second electrolytic solution flows are individually provided in each of the at least two or more cell stacks; each of the at least two or more cell stacks includes a cell stack input terminal and a cell stack output terminal; a bypass circuit that electrically bypasses the cell stack is provided for each of the at least two or more cell stacks; each of the bypass circuits includes a bypass circuit input terminal and a bypass circuit output terminal; an input switch for switching between the cell stack input terminal and the bypass circuit input terminal, and an output switch for switching between the cell stack output terminal and the bypass circuit output terminal, for each of the at least two or more cell stacks; the at least one series circuit includes at least two or more series circuits electrically connected in parallel; a connection circuit electrically connecting the at least two series circuits in parallel, Between the connection circuit and each of the at least two or more series circuits, a first diode is provided for allowing a current to flow only from the connection circuit to the series circuit, a second diode is provided for allowing a current to flow only from the series circuit to the connection circuit, and a changeover switch is provided for connecting the connection circuit to either the first diode or the second diode. Redox flow battery.

2. the output switch is switched from the cell stack output terminal to the bypass circuit output terminal when the input switch is switched from the cell stack input terminal to the bypass circuit input terminal, and is switched from the bypass circuit output terminal to the cell stack output terminal when the input switch is switched from the bypass circuit input terminal to the cell stack input terminal. The redox flow battery according to claim 1.

3. 3. The redox flow battery according to claim 1, wherein the changeover switch is configured to switch to the first diode during charging and to switch to the second diode during discharging.

4. the at least one cell includes at least two or more cells electrically connected in parallel; the first distribution path includes a first supply path branching to connect to each of the at least two or more cells, and a first recovery path connected to each of the at least two or more cells, the second distribution path includes a second supply path branching to connect to each of the at least two or more cells, and a second recovery path connected to each of the at least two or more cells. The redox flow battery according to any one of claims 1 to 3.

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