JP2013037814A - Electrolyte circulation battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte circulation battery in which the amount of electrolyte can be adjusted in a short time when the difference in the amount of electrolyte (amount of active material) between the positive electrode side and the negative electrode side goes above a predetermined level.SOLUTION: A redox flow cell 1A includes a battery cell 10 having a positive electrode cell 102 and a negative electrode cell 103, a positive electrode tank 20 and a negative electrode tank 30 for storing the positive electrode electrolyte and the negative electrode electrolyte, positive electrode side and negative electrode side circulation passages 25, 35 for circulating respective electrolytes between the tanks 20, 30 and the cells 102, 103, an interconnection pipe 50 interconnecting the positive electrode tank 20 and the negative electrode tank 30, and a valve 51 for opening or closing the interconnection pipe 50. The numbers of the positive electrode tanks 20 and the negative electrode tanks 30 are different from each other, and the total cross sectional areas of the internal spaces of the positive electrode tanks 20 and the negative electrode tanks 30 are different from each other in the horizontal direction, at least above a reference plane when the positive electrode tanks 20 and the negative electrode tanks 30 have the same liquid level.

Description

  The present invention relates to an electrolyte flow type battery capable of adjusting the amount of electrolyte in a short time when a difference of a predetermined amount or more is generated between the amount of electrolyte (active material) on the positive electrode side and the negative electrode side.

  In recent years, the introduction of wind power generation and solar power generation using renewable energy such as wind power and sunlight has been promoted worldwide as a countermeasure against global warming. Since these power generation outputs are affected by the weather, large-scale introduction of power generation using renewable energy has a problem of causing frequency fluctuations and voltage fluctuations of the power system. As one of countermeasures against this problem, it has been proposed to install a large capacity storage battery to smooth output fluctuation, store surplus power, and level load.

  One type of large-capacity storage battery is an electrolyte flow type battery such as a redox flow battery. A redox flow battery performs charge / discharge by supplying a positive electrode electrolyte and a negative electrode electrolyte to battery cells in which a diaphragm is interposed between a positive electrode and a negative electrode. As the electrolytic solution, an aqueous solution containing metal ions whose valence changes by oxidation and reduction is generally used. As a redox flow battery, a vanadium redox flow battery using a vanadium ion aqueous solution as a positive and negative electrolyte solution is well known (for example, see Patent Documents 1 and 2).

  FIG. 9 is a schematic diagram for explaining a basic configuration of an electrolyte flow type battery (redox flow battery). The redox flow battery 100 includes a battery cell 10. The battery cell 10 includes a positive electrode cell 102 and a negative electrode cell 103 separated by a diaphragm 101 made of an ion permeable membrane, and the positive electrode cell 102 and the negative electrode cell 103 contain a positive electrode 104 and a negative electrode 105, respectively. The battery cell 10 is generally used in a form called a cell stack in which a plurality of unit cells each composed of a positive electrode 102, a diaphragm 101, and a negative electrode 103 are stacked. The redox flow battery 100 includes a positive electrode tank 20 and a negative electrode tank 30 that store a positive electrode electrolyte and a negative electrode electrolyte, and a positive electrode electrolyte and a negative electrode tank 30 between the positive electrode tank 20 and the negative electrode tank 30, and the positive electrode cell 102 and the negative electrode cell 103. And a circulation path 25, 35 on the positive electrode side and the negative electrode side for circulating the negative electrode electrolyte. Each circulation path 25, 35 is provided with a pump 40 for circulating each electrolyte. The positive electrode side circulation path 25 includes an outward piping 26 that sends the positive electrolyte solution from the positive electrode tank 20 to the positive electrode cell 102, and a return piping 27 that returns the positive electrolyte solution from the positive electrode cell 102 to the positive electrode tank 20. The negative electrode side circulation path 35 includes an outward piping 36 that sends the negative electrode electrolyte from the negative electrode tank 30 to the negative electrode cell 103, and a return piping 37 that returns the negative electrode electrolyte from the negative electrode cell 103 to the negative electrode tank 30.

  In this redox flow battery 100, the outgoing pipes 26, 36 of the circulation paths 25, 35 are connected so as to communicate the lower parts of the tanks 20, 30 and the lower parts of the cells 102, 103, and the upper parts of the tanks 20, 30 are connected. The return pipes 27 and 37 of the circulation paths 25 and 35 are connected so as to communicate with the upper portions of the cells 102 and 103. Then, the respective electrolytes are sent from the tanks 20 and 30 to the cells 102 and 103 via the forward pipes 26 and 36 by the pumps 40 provided in the forward pipes 26 and 36 of the circulation paths 25 and 35, respectively. The electrolytes supplied to the cells 102 and 103 are discharged upward from the lower sides of the cells 102 and 103 and returned to the tanks 20 and 30 through the return pipes 27 and 37 for circulation. In the battery cell 10, a battery reaction (charge / discharge reaction) is performed. In addition, in the redox flow battery 100 shown in FIG. 9, the case where vanadium ion aqueous solution is used for the electrolyte solution of positive and negative electrodes is mentioned as an example. Moreover, the solid line arrow in a battery cell in FIG. 9 shows a charging reaction, and the broken line arrow shows a discharging reaction, respectively.

  Usually, in a redox flow battery, as disclosed in Patent Documents 1 and 2, the numbers of positive electrode tanks and negative electrode tanks are equal.

JP 2003-303611 A JP 2002-329522 A

  In an electrolyte solution-type battery (redox flow battery), the active material in the electrolyte solution passes through a diaphragm from one cell of the positive electrode cell or the negative electrode cell to the other cell in the battery cell with repeated charge and discharge during operation. Or the phenomenon of solvent migration (sometimes called “liquid transfer”). Thereby, a difference arises in the amount of electrolyte solution (active material amount) on the positive electrode side and the amount of electrolyte solution (active material amount) on the negative electrode side, and the battery capacity (discharge capacity) is reduced accordingly.

  Therefore, it is desirable to provide a mechanism for adjusting the amount of electrolyte between the positive and negative electrodes when a difference of a predetermined value or more is generated between the amount of electrolyte (active material) on the positive electrode side and the negative electrode side. Typically, the positive electrode tank and the negative electrode tank are communicated with each other through a communication pipe, and a valve is provided on the communication pipe. When a difference of more than a predetermined level occurs between the positive and negative electrode tanks, the valve is opened and the communication pipe is opened, so that the liquid level of the positive and negative tanks is the same. Make adjustments.

  The present invention has been made in view of the above circumstances, and one of its purposes is that when there is a difference of a predetermined amount or more in the amount of electrolyte solution (active material amount) between the positive electrode side and the negative electrode side, the electrolyte solution An object of the present invention is to provide an electrolyte solution-type battery capable of adjusting the amount in a short time.

  The electrolyte flow type battery of the present invention includes a battery cell, a positive electrode tank and a negative electrode tank, a positive electrode side circulation path and a negative electrode side circulation path, a communication pipe, and an opening / closing means. The battery cell has a positive electrode cell and a negative electrode cell. The positive electrode tank and the negative electrode tank store a positive electrode electrolyte and a negative electrode electrolyte. The positive electrode side circulation path and the negative electrode side circulation path circulate the positive electrode electrolyte and the negative electrode electrolyte solution between the positive electrode tank and the negative electrode tank and the positive electrode cell and the negative electrode cell. The communication pipe communicates the positive electrode tank and the negative electrode tank. The opening / closing means opens and closes the communication pipe. In addition, the number of the positive electrode tanks and the negative electrode tanks is different, and the liquid level when the liquid levels of the positive electrode tank and the negative electrode tank are the same height is used as a reference surface, and the internal spaces of the positive electrode tank and the negative electrode tank at least above the reference surface The total cross-sectional areas in the horizontal direction are different.

  According to this configuration, when there is a predetermined difference or more in the amount of electrolyte on the positive electrode side and the negative electrode side, the communication pipe is opened from one tank whose liquid volume has increased by opening the communication pipe by the opening / closing means. The amount of the electrolytic solution can be adjusted by moving the electrolytic solution to the other tank in which the amount of the liquid is reduced via the. The movement of the electrolytic solution at this time utilizes the level difference (gravity) between the liquid levels of one tank and the other tank, and the moving speed of the electrolytic solution increases as the liquid level difference increases.

  When the liquid volume increasing side of the positive electrode tank and the negative electrode tank is the tank having the smaller total cross-sectional area, when the liquid amount increases, the electrolytic solution accumulates in the internal space above the reference surface of the tank. For this reason, the liquid level of the tank is higher than when the total cross-sectional areas of the positive electrode tank and the negative electrode tank are equal. Therefore, during operation, when the amount of liquid in the tank having the smaller total cross-sectional area increases and a difference of a predetermined amount or more occurs between the amount of electrolyte solution (active material amount) on the positive electrode side and the negative electrode side, the positive electrode tank and the negative electrode The liquid level difference in the tank increases. Therefore, when the communicating pipe is opened by the opening / closing means and the electrolytic solution is moved through the communicating pipe, the moving speed of the electrolytic solution is increased, so that the amount of the electrolytic solution can be adjusted in a short time. In addition, since the adjustment time of the electrolyte amount is shortened, the self-discharge generated by mixing the electrolyte solution of the positive and negative electrodes by shortening the open state of the communication pipe (communication state of the positive electrode tank and the negative electrode tank). The loss due to can be minimized.

  Further, in the tank with the smaller total cross-sectional area, the total cross-sectional area in the horizontal direction of the internal space below the reference plane is also small, that is, the horizontal direction of the internal space over the entire vertical (height) direction of the tank. The total cross-sectional area at may be reduced. In this case, when the liquid levels of the positive electrode tank and the negative electrode tank are the same, the amount of liquid in the tank with the smaller total cross-sectional area is smaller than that of the larger tank. Here, when the liquid volume increasing side of the positive electrode tank and the negative electrode tank is the tank having the smaller total cross-sectional area, the smaller tank is increased by increasing the liquid amount of the smaller tank during operation. The liquid volume in the larger tank is equal, and in this state, the rated battery capacity is obtained. Then, if the operation is continued until a predetermined difference or more in the amount of electrolyte solution on the positive electrode side and the negative electrode side occurs, the positive electrode tank and the negative electrode tank are compared with the case where the total cross-sectional areas of the positive electrode tank and the negative electrode tank are equal. The time until the liquid volume difference becomes equal to or greater than a predetermined time is increased, and the liquid level difference at that time is also increased. Therefore, it is possible to extend the time required for the liquid amount difference to become a predetermined value or more, and to reduce the number of times of adjusting the amount of the electrolytic solution. Therefore, the self-discharge generated by mixing the positive and negative electrolytic solutions accordingly. The loss due to can be minimized.

  In the present invention, basically, of the positive electrode tank and the negative electrode tank, the side with the smaller number of tanks is the tank with the smaller total cross-sectional area, and the side on which the liquid volume increases during operation is the total cross-sectional area. Use the smaller tank.

  As an embodiment of the electrolyte flow type battery of the present invention, a cross-sectional area reduction portion for reducing the total cross-sectional area is provided in the tank having the smaller total cross-sectional area of the positive electrode tank and the negative electrode tank. Can be mentioned.

  The means for reducing the total cross-sectional area can be realized by reducing the shape of the internal space of the tank in the horizontal cross-section so that the total cross-sectional area becomes small, or by providing a cross-sectional area reducing portion in the tank. it can. As the cross-sectional area reduction portion, for example, a member having a predetermined shape is arranged so as to be positioned in the internal space above the reference plane of the tank, or is positioned over the entire vertical (height) direction of the internal space of the tank. You may arrange as follows. In the latter case, since the amount of liquid in the tank with the smaller total cross-sectional area is smaller than that of the larger tank, as described above, the number of times of adjusting the amount of electrolyte can be reduced. Accordingly, loss due to self-discharge can be reduced. As an example, a columnar object is installed in the tank, and the shape in the horizontal section of the internal space of the tank is made into a ring shape.

  As an embodiment of the electrolyte flow type battery of the present invention, a liquid level raising part for raising the liquid level of the tank having the smaller total cross-sectional area of the positive electrode tank and the negative electrode tank is provided.

  Since the liquid level raising portion is provided, the amount of liquid in the tank with the smaller total cross-sectional area is smaller than that with the larger tank, so that the amount of electrolyte is adjusted as described above. Since the number of times can be reduced, the loss due to self-discharge can be reduced accordingly. Examples of the liquid level raising part include sinking or floating an object in the electrolytic solution in the tank. As an object to be submerged or floated, a member made of resin or a member coated with resin can be used. This member can be a solid or hollow member, and when it is a hollow member, the hollow space may be filled with an electrolytic solution. For example, when a resin container filled with an electrolyte is submerged or floated in the electrolyte in the tank, even if the container is torn due to corrosion or the like, the electrolyte inside only flows out into the tank. It does not interfere with battery operation.

  In addition, the liquid level raising portion can be realized by raising the installation surface of the tank or raising the bottom of the tank.

  In the electrolyte flow type battery of the present invention, the number of positive electrode tanks and negative electrode tanks is different, and the total cross-sectional area in the horizontal direction is different in the internal space above the reference surface of the positive electrode tank and the negative electrode tank. When there is a difference of a predetermined amount or more in the amount of the electrolytic solution (active material amount), the amount of the electrolytic solution can be adjusted in a short time.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram for demonstrating the redox flow battery which concerns on Example 1, (A) shows the state with the same liquid level height of a positive electrode tank and a negative electrode tank, (B) increases the liquid quantity of a positive electrode tank. In this state, the amount of liquid in the negative electrode tank is reduced. It is a schematic diagram for demonstrating the redox flow battery which concerns on the modification 1, (A) shows the state where the liquid level of a positive electrode tank and a negative electrode tank is the same, (B) increases the liquid quantity of a positive electrode tank In this state, the amount of liquid in the negative electrode tank is reduced. It is a schematic diagram for demonstrating the redox flow battery which concerns on Example 2, (A) shows the state with the same liquid level height of a positive electrode tank and a negative electrode tank, (B) increases the liquid quantity of a positive electrode tank. In this state, the amount of liquid in the negative electrode tank is reduced. It is a schematic diagram for demonstrating the redox flow battery which concerns on Example 3, (A) shows the state with the same liquid level height of a positive electrode tank and a negative electrode tank, (B) increases the liquid quantity of a positive electrode tank. In this state, the amount of liquid in the negative electrode tank is reduced. It is a schematic diagram for demonstrating the redox flow battery which concerns on the modification 2, (A) shows the state with the same liquid level height of a positive electrode tank and a negative electrode tank, (B) increases the liquid quantity of a positive electrode tank In this state, the amount of liquid in the negative electrode tank is reduced. 10 is a schematic diagram for explaining a redox flow battery according to Modification 3. FIG. 10 is a schematic diagram for explaining a redox flow battery according to Modification 4. FIG. It is a schematic diagram for demonstrating the redox flow battery which concerns on the comparative example 1, (A) shows the state with the same liquid level height of a positive electrode tank and a negative electrode tank, (B) increases the liquid quantity of a positive electrode tank. In this state, the amount of liquid in the negative electrode tank is reduced. It is a schematic diagram for demonstrating the basic composition of a redox flow battery.

  Along with a comparative example, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

(Comparative Example 1)
The basic configuration of the redox flow battery 1N according to Comparative Example 1 shown in FIG. 8 is the same as that of the redox flow battery 100 described with reference to FIG. 9. One of the features of the redox flow battery 1N is that the positive electrode tank 20 and the negative electrode A communication pipe 50 that communicates with the tank 30 and an opening / closing means (valve) 51 that opens and closes the communication pipe are provided. Hereinafter, only the outline of the basic configuration of the redox flow battery 1N will be described, and the feature points will be mainly described.

  The redox flow battery 1N includes a battery cell 10, a positive electrode tank 20 and a negative electrode tank 30 that store a positive electrode electrolyte and a negative electrode electrolyte, and a positive electrode between the positive electrode tank 20, the negative electrode tank 30, the positive electrode cell 102, and the negative electrode cell 103. A positive electrode side circulation path 25 and a negative electrode side circulation path 35 that circulate the electrolyte solution and the negative electrode electrolyte solution are provided, and a pump 40 that circulates each electrolyte solution is provided in each of the circulation paths 25 and 35. The battery cell 10 is divided into a positive electrode cell 102 and a negative electrode cell 103 by a diaphragm 101 made of an ion permeable membrane, and the positive electrode cell 102 and the negative electrode cell 103 each have a built-in positive electrode and a negative electrode. The positive electrode side circulation path 25 includes an outward piping 26 that sends the positive electrolyte solution from the positive electrode tank 20 to the positive electrode cell 102, and a return piping 27 that returns the positive electrolyte solution from the positive electrode cell 102 to the positive electrode tank 20. The negative electrode side circulation path 35 includes an outgoing pipe 36 that sends the negative electrode electrolyte from the negative electrode tank 30 to the negative electrode cell 103, and a return pipe 37 that returns the negative electrode electrolyte from the negative electrode cell 103 to the negative electrode tank 30. In this example, the battery cell 10 is supported by a gantry (not shown) and is installed at a position higher than the positive electrode tank 20 and the negative electrode tank 30.

  Here, when describing the positive and negative electrode electrolytes, it is mentioned that the positive and negative electrode electrolytes contain the same metal ion species as the active material. For example, each of the positive and negative electrode electrolytic solutions may be an electrolytic solution containing vanadium ions as an active material, or an electrolytic solution containing manganese ions or titanium ions, or both manganese ions and titanium ions. When an electrolytic solution containing both manganese ions and titanium ions is used for the positive and negative electrode electrolytic solutions, a high electromotive force is obtained and the generation of precipitates is also suppressed.

  Each of the positive electrode tank 20 and the negative electrode tank 30 is one, and the shape and size are also the same. In both the positive electrode tank 20 and the negative electrode tank 30, the cross-sectional area in the horizontal direction of the internal space is constant over the entire vertical (height) direction of the tank. The positive electrode tank 20 and the negative electrode tank 30 have the same total cross-sectional area in the horizontal direction of the internal space over the entire vertical (height) direction of the tank. The shape of the tank is not particularly limited, and for example, an arbitrary shape such as a circular shape, a polygonal shape, or an elliptical shape can be adopted as the cross-sectional shape in the horizontal direction of the internal space of the tank.

  The communication pipe 50 communicates the liquid phase portion of the positive electrode tank 20 and the liquid phase portion of the negative electrode tank 30 when the liquid levels of the positive electrode tank 20 and the negative electrode tank 30 are the same height (see FIG. 8A). It is connected to the. Further, the communication pipe 50 is provided with a valve 51, and the open / close state of the communication pipe 50 can be switched by opening / closing the valve 51. Normally, the valve 51 is closed to close the communication pipe 50 so that the positive and negative electrolytes are not mixed.

  During operation, when a difference of a predetermined value or more is generated between the positive electrode side and the negative electrode side, the valve 51 is opened and the communication pipe 50 is opened, so that the liquid in the positive electrode tank 20 and the negative electrode tank 30 is The electrolytic solution is moved using the surface difference, and the amount of the electrolytic solution is adjusted so that the liquid surfaces of the positive electrode tank 20 and the negative electrode tank 30 are the same height. After adjusting the amount of the electrolyte, the valve 51 is closed to close the communication pipe 50. For example, as shown in FIG. 8B, during the operation, liquid transfer occurs in which the electrolytic solution moves from the negative electrode side to the positive electrode side, the liquid amount in the positive electrode tank 20 increases, and the liquid amount in the negative electrode tank 30 decreases. When the liquid level difference between the positive electrode tank 20 and the negative electrode tank 30 becomes a predetermined value or more, the electrolytic solution is moved from the positive electrode tank 20 to the negative electrode tank 30 through the communication pipe 50 to adjust the electrolytic solution amount. The amount of the electrolyte moved by the liquid transfer can be detected by attaching a liquid level sensor or the like in the tank.

Example 1
The redox flow battery 1A according to the first embodiment shown in FIG. 1 is the same as the redox flow battery 1N of the first comparative example shown in FIG. 8 except that the configuration of the tank is different. To do.

  In the redox flow battery 1A, the number of tanks of the positive electrode tank 20 and the negative electrode tank 30 is different. In this example, the negative electrode tank 30 includes a first negative electrode tank 31 and a second negative electrode tank 32, and one positive electrode tank 20 is provided. The tank 30 is composed of two tanks. The positive electrode tank 20, the first negative electrode tank 31, and the second negative electrode tank 32 all have a constant cross-sectional area in the horizontal direction of the internal space over the entire vertical (height) direction of the tank. The first negative electrode tank 31 and the second negative electrode tank 32 communicate with each other through the communication pipe 60, and the liquid level is the same. Further, the positive electrode tank 20 and the negative electrode tank 30 have different total cross-sectional areas in the horizontal direction of the internal space over the entire vertical (height) direction of the tank, and the positive electrode tank 20 has a larger total cross-sectional area than the negative electrode tank 30. small. Specifically, the positive electrode tank 20 and the first negative electrode tank 31 have the same shape and size, and the negative electrode tank 30 has a larger capacity than the positive electrode tank 20 by the amount of the second negative electrode tank 32. That is, when the liquid levels of the positive electrode tank 20 and the negative electrode tank 30 are the same level (see FIG. 1A), the amount of liquid in the positive electrode tank 20 is smaller than that of the negative electrode tank 30. In addition, the forward piping 36 and the return piping 37 of the negative electrode side circulation path 35 are connected only to the first negative electrode tank 31.

  The adjustment of the amount of electrolyte in the redox flow battery 1A will be described in comparison with the redox flow battery 1N of Comparative Example 1 shown in FIG. During operation, when a difference of a predetermined value or more is generated between the positive electrode side and the negative electrode side, the valve 51 is opened and the communication pipe 50 is opened, so that the liquid levels of the positive electrode tank 20 and the negative electrode tank 30 are changed. The point of adjusting the amount of the electrolyte so as to be the same height is the same. For example, as shown in FIG. 1B, the liquid transfer described above occurs, the liquid volume in the positive electrode tank 20 increases, the liquid volume in the negative electrode tank 30 decreases, and the liquid volume difference between the positive electrode tank 20 and the negative electrode tank 30 Is equal to or greater than a predetermined value, the electrolytic solution is moved from the positive electrode tank 20 to the negative electrode tank 30 via the communication pipe 50 to adjust the amount of the electrolytic solution.

  Here, for easy understanding, the total cross-sectional area in the horizontal direction of the internal space of the negative electrode tank 30 of the redox flow battery 1A and the negative electrode tank 30 of the redox flow battery 1N (hereinafter sometimes simply referred to as “total cross-sectional area”). It is assumed that the positive electrode tank 20 of the redox flow battery 1A has a smaller total cross-sectional area than the positive electrode tank 20 of the redox flow battery 1N.

  For example, in the redox flow battery 1N, when the liquid levels of the positive electrode tank 20 and the negative electrode tank 30 are the same height (see FIG. 8A), the liquid volume of the positive electrode tank is 100, the liquid volume of the negative electrode tank is 100, The liquid volume is 200. Then, it is assumed that when the amount of liquid in the positive electrode tank 20 becomes 20 larger than the amount of liquid in the negative electrode tank 30, the communication pipe 50 is opened by the valve 51 and the adjustment of the amount of electrolytic solution is started. In this case, when the electrolyte moves from the negative electrode side to the positive electrode side and the amount of liquid in the positive electrode tank increases by 10, the amount of liquid in the positive electrode tank becomes 110, the amount of liquid in the negative electrode tank becomes 90, and adjustment of the amount of electrolytic solution To start.

  On the other hand, in the redox flow battery 1A, for example, when the liquid levels of the positive electrode tank 20 and the negative electrode tank 30 are the same height so that the total liquid amount is the same as the above-described redox flow battery 1N (see FIG. 1A). ), The liquid volume in the positive electrode tank is 90, the liquid volume in the negative electrode tank is 110, the total liquid volume is 200, and the conditions for starting the adjustment of the electrolyte volume are the same. In this case, when the electrolyte moves from the negative electrode side to the positive electrode side and the liquid volume in the positive electrode tank increases by 10, the liquid volume in the positive electrode tank and the negative electrode tank becomes equal (both are 100). It becomes. Furthermore, when the electrolytic solution moves from the negative electrode side to the positive electrode side and the amount of increase in the amount of liquid in the positive electrode tank reaches 20, the amount of liquid in the positive electrode tank becomes 110, the amount of liquid in the negative electrode tank becomes 90, and the electrolytic solution Start adjusting the amount.

  That is, in the case of the redox flow battery 1A, as compared with the above-described redox flow battery 1N, the time until the adjustment of the electrolyte amount starts, that is, until the difference in the liquid amount between the positive electrode tank 20 and the negative electrode tank 30 becomes a predetermined value or more. The time will be longer. Therefore, since the number of times of adjusting the amount of the electrolyte can be reduced, the loss due to self-discharge caused by mixing the positive and negative electrolytes can be reduced accordingly. In addition, since the amount of increase in the amount of liquid in the positive electrode tank until the adjustment of the amount of electrolyte increases, the liquid level of the positive electrode tank 20 is higher than that of the redox flow battery 1N described above, and the positive electrode tank 20 The liquid level difference in the negative electrode tank 30 also increases.

  Furthermore, in the case of the redox flow battery 1A, since the total cross-sectional area of the positive electrode tank 20 is smaller than the negative electrode tank 30, the height of the liquid level when the liquid amount increases in the positive electrode tank 20 is compared with the above-described redox flow battery 1N. And get higher. That is, when the amount of the electrolytic solution is adjusted, the liquid level difference between the positive electrode tank 20 and the negative electrode tank 30 increases. Therefore, when the electrolyte solution is moved from the positive electrode tank 20 to the negative electrode tank 30 through the communication pipe 50, the moving speed of the electrolyte solution through the communication pipe 50 is increased, so that the amount of the electrolyte solution can be adjusted in a short time. Can do. In addition, since the adjustment time of the amount of electrolyte is shortened, the time for the open state of the communication pipe 50 (the communication state of the positive electrode tank 20 and the negative electrode tank 30) is shortened and the positive and negative electrode electrolytes are mixed. Loss due to self-discharge that occurs can also be reduced.

(Modification 1)
In the redox flow battery 1A according to the first embodiment shown in FIG. 1 described above, the case where the positive electrode tank 20 has a constant cross-sectional area in the horizontal direction of the internal space over the entire vertical (height) direction of the tank is described. did. In the redox flow battery 1B according to the modified example 1 shown in FIG. 2, in the positive electrode tank 20, when the liquid level when the liquid levels of the positive electrode tank 20 and the negative electrode tank 30 are the same height is used as the reference surface, The case where the total cross-sectional area in the horizontal direction of the upper internal space (upper space) 20u is different from the total cross-sectional area in the horizontal direction of the internal space (lower space) 20d below the reference plane will be described.

  In the redox flow battery 1B, the total sectional area of the upper space 20u in the positive electrode tank 20 is smaller than the total sectional area of the lower space 20d. Specifically, when the positive electrode tank 20 and the negative electrode tank 30 are compared, the total cross-sectional area of the upper space 20u of the positive electrode tank 20 is smaller than the total cross-sectional area of the negative electrode tank 30, and the lower space 20d of the positive electrode tank 20 The total cross-sectional area is equal to the total cross-sectional area of the negative electrode tank 30. That is, when the liquid levels of the positive electrode tank 20 and the negative electrode tank 30 are the same height (see FIG. 2A), the liquid amounts of the positive electrode tank 20 and the negative electrode tank 30 are equal.

  The adjustment of the amount of electrolyte in the redox flow battery 1B will be described. When the liquid levels of the positive electrode tank 20 and the negative electrode tank 30 are the same level (see FIG. 2A), the liquid in the positive electrode tank 20 and the negative electrode tank 30 Since the amounts are equal, it is not possible to extend the time required until the liquid level difference between the positive electrode tank 20 and the negative electrode tank 30 becomes equal to or more than a predetermined value as in the redox flow battery 1A described above. That is, the number of times of adjusting the amount of the electrolyte cannot be reduced. However, when the amount of liquid in the positive electrode tank 20 increases (see FIG. 2 (B)), the amount of the increased liquid is accumulated in the upper space 20u having a small total cross-sectional area, so that it is the same as the redox flow battery 1A described above. Moreover, the liquid level of the positive electrode tank 20 becomes high. Therefore, when the amount of the electrolytic solution is adjusted, the liquid level difference between the positive electrode tank 20 and the negative electrode tank 30 becomes large, so that the amount of the electrolytic solution can be adjusted in a short time.

(Example 2)
The redox flow battery 1C according to the second embodiment shown in FIG. 3 is the same as the redox flow battery 1A according to the first embodiment shown in FIG. 1 except that the configuration of the tank is different. The following description focuses on the differences. To do.

  In the redox flow battery 1C, the positive electrode tank 20 has the same shape and size as the positive electrode tank 20 of the redox flow battery 1N according to Comparative Example 1 shown in FIG. A cross-sectional area reduction unit 70 is provided. The cross-sectional area reducing portion 70 is a solid or hollow columnar member. In this example, the cross-sectional area reducing portion 70 extends from the bottom surface to the upper surface at the center of the positive electrode tank 20, and extends in the vertical (height) direction of the internal space of the tank. Are arranged. In other words, the positive electrode tank 20 of the redox flow battery 1C has a reduced total cross-sectional area in the horizontal direction of the internal space over the entire vertical (height) direction of the tank, like the positive electrode tank 20 of the redox flow battery 1A. It is smaller than the case without part 70.

  The adjustment of the amount of electrolyte in the redox flow battery 1C will be described. When the liquid levels of the positive electrode tank 20 and the negative electrode tank 30 are the same as in the above-described redox flow battery 1A (see FIG. 3A). ) Since the amount of liquid in the positive electrode tank 20 is smaller than that in the negative electrode tank 30, the time until the liquid amount difference between the positive electrode tank 20 and the negative electrode tank 30 becomes equal to or larger than a predetermined time is increased, and the number of times of adjustment of the electrolyte amount Can be reduced. Further, since the amount of increase in the amount of liquid in the positive electrode tank until the adjustment of the amount of electrolytic solution is increased, the liquid level of the positive electrode tank 20 is increased, and the liquid level difference between the positive electrode tank 20 and the negative electrode tank 30 is also increased. Further, when the amount of liquid in the positive electrode tank 20 increases (see FIG. 3B), the total cross-sectional area of the positive electrode tank 20 is smaller than that of the negative electrode tank 30, so that the liquid level of the positive electrode tank 20 increases. The liquid level difference of the negative electrode tank 30 increases. Therefore, the amount of the electrolytic solution can be adjusted in a short time.

(Example 3)
The redox flow battery 1D according to the third embodiment shown in FIG. 4 is the same as the redox flow battery 1A according to the first embodiment shown in FIG. 1 except that the configuration of the tank is different. The following description focuses on the differences. To do.

  In the redox flow battery 1D, a liquid level raising portion 75 for raising the liquid level of the positive electrode tank 20 is provided. In this example, the liquid level raising portion 75 is formed by sinking a member made of resin or a plate member such as metal coated with resin in the positive electrode tank 20. This member is a solid or hollow member, and in the case of a hollow member, the hollow space may be filled with an electrolytic solution.

  The adjustment of the amount of the electrolytic solution in the redox flow battery 1D will be described, and the same effect as the redox flow battery 1A described above can be obtained. Furthermore, since the liquid level raising portion 75 is provided, the amount of the liquid in the positive electrode tank 20 becomes smaller than that in the negative electrode tank 30, so that the number of times of adjusting the amount of the electrolytic solution can be further reduced. In addition, since the amount of increase in the amount of liquid in the positive electrode tank 20 until the adjustment of the amount of electrolytic solution begins to increase, the liquid level of the positive electrode tank 20 becomes higher, and the liquid level difference between the positive electrode tank 20 and the negative electrode tank 30 also increases. It becomes larger (see FIGS. 4A and 4B). Therefore, the amount of the electrolytic solution can be adjusted in a shorter time.

(Modification 2)
In the redox flow battery 1D according to the third embodiment shown in FIG. 4 described above, the liquid level raising portion 75 is realized by sinking the plate-like member in the positive electrode tank 20, but the liquid level of the positive electrode tank 20 is increased. The liquid level raising part 75 can also be realized by other means. For example, like the redox flow battery 1E according to Modification 2 shown in FIG. Alternatively, the bottom of the positive electrode tank 20 may be raised.

(Modification 3)
In the redox flow battery 1A according to the first embodiment shown in FIG. 1 described above, the case where the first negative electrode tank 31 and the second negative electrode tank 32 are communicated with each other through the communication pipe 60 has been described. For example, the third modification shown in FIG. A plurality of the communication pipes 60 may be provided like the redox flow battery 1F.

(Modification 4)
Further, for example, as in the redox flow battery 1G according to Modification 4 shown in FIG. 7, the forward piping 36 and the return piping 37 of the negative electrode side circulation path 35 are branched, and the outward piping 36 and the return piping 37 are connected to the second negative electrode tank 32. In addition, the communication pipe 50 may be branched and the communication pipe 50 may also be connected to the second negative electrode tank 32. In this case, the discharge amount of the electrolytic solution from the first negative electrode tank 31 and the second negative electrode tank 32 and the first negative electrode tank 31 so that the liquid surfaces of the first negative electrode tank 31 and the second negative electrode tank 32 are the same. And the supply amount of the electrolytic solution to the second negative electrode tank 32 is adjusted. Thereby, it is not necessary to use a communication pipe.

  In the above-described embodiments and modifications, the case where the electrolytic solution moves from the negative electrode side to the positive electrode side and the liquid amount of the positive electrode tank increases during operation is described. What is necessary is just to replace the structure of a positive electrode tank and a negative electrode tank. Also, the number of both positive and negative tanks may be two, and the number of negative tanks may be three.

  Note that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the gist of the present invention.

  The electrolyte flow type battery of the present invention can be suitably used, for example, in the field of redox flow batteries.

1A, 1B, 1C, 1D, 1E, 1F, 1G, 1N, 100 Electrolyte flow type battery (redox flow battery)
10 battery cells
101 Diaphragm 102 Positive electrode cell 103 Negative electrode cell
104 Positive electrode 105 Negative electrode
20 Positive tank 20u Upper space 20d Lower space
25 Positive side circulation path 26 Outward piping 27 Return piping
30 Negative electrode tank
31 First negative tank 32 Second negative tank
35 Negative side circulation path 36 Outward piping 37 Return piping
40 Circulation pump
50 Communication pipe 51 Opening / closing means (valve)
60 communication pipe
70 Cross-sectional area reduction part
75 Liquid level raising part

Claims (3)

A battery cell having a positive electrode cell and a negative electrode cell;
A positive electrode tank and a negative electrode tank for storing a positive electrode electrolyte and a negative electrode electrolyte;
A positive electrode side circulation path and a negative electrode side circulation path for circulating the positive electrode electrolyte and the negative electrode electrolyte between the positive electrode tank and the negative electrode tank and the positive electrode cell and the negative electrode cell,
A communication pipe communicating the positive electrode tank and the negative electrode tank;
Open / close means for opening and closing the communication pipe, and the number of the positive electrode tank and the negative electrode tank is different, and the liquid level when the liquid level of the positive electrode tank and the negative electrode tank is the same height, The electrolyte flow type battery, wherein a total cross-sectional area in the horizontal direction of the internal space of the positive electrode tank and the negative electrode tank is different at least above the reference plane.   2. The electrolysis according to claim 1, wherein a cross-sectional area reduction portion for reducing the total cross-sectional area is provided in a tank having the smaller total cross-sectional area of the positive electrode tank and the negative electrode tank. Liquid-flow battery.   3. The electrolytic solution circulation according to claim 1, wherein a liquid level raising portion is provided for raising the liquid level of the tank having the smaller total cross-sectional area of the positive electrode tank and the negative electrode tank. Type battery.

Images