JP2013008640A - Redox flow cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a redox flow cell capable of producing a high electromotive force.SOLUTION: A redox flow cell performs charging and discharging operation by supplying a battery element having an electrode with a positive electrode electrolyte and a negative electrode electrolyte. The redox flow cell includes: at least one of either a positive electrode electrolyte containing an Mn ion as a positive electrode active material, and a negative electrode electrolyte containing a Ti ion as a negative electrode active material; an agitation mechanism 1 for agitating an electrolyte in a tank (positive electrode tank 106) storing an electrolyte containing the Mn ion or the Ti ion; and control means 9 for controlling the motion of the agitation mechanism 1. Since the agitation mechanism 1 can eliminate the uneven distribution of the charging state active material ion and the discharging state active material ion in the electrolyte, the redox flow cell can perform effective charge and discharge operations.

Description

  The present invention relates to a redox flow battery capable of obtaining a high electromotive force.

  In recent years, introduction of new energy such as solar power generation and wind power generation has been promoted worldwide as a countermeasure against global warming. Since these power generation outputs are affected by the weather, it is predicted that there will be a problem in the operation of the electric power system such that it becomes difficult to maintain the frequency and voltage when the mass introduction is advanced. As one of the countermeasures against this problem, it is expected to install a large-capacity storage battery to smooth the output fluctuation, save surplus power, and level the load.

  One of the large-capacity storage batteries is a redox flow battery. In a redox flow battery, charge and discharge are performed by supplying a positive electrode electrolyte and a negative electrode electrolyte respectively to a battery element in which a diaphragm is interposed between a positive electrode and a negative electrode. As the electrolytic solution, typically, an aqueous solution containing metal ions whose valence changes by oxidation-reduction is used. Typical examples include an iron-chromium redox flow battery using iron ions for the positive electrode and Cr ions for the negative electrode, and a vanadium redox flow battery using V ions for both the positive electrode and the negative electrode (for example, Patent Document 1).

JP 2006-147374 A

  Vanadium redox flow batteries have been put to practical use and are expected to be used in the future. However, the conventional iron-chromium redox flow battery and vanadium redox flow battery cannot be said to have a sufficiently high electromotive force. To meet future global demand, a new redox that has a higher electromotive force and can stably supply metal ions used in active materials, preferably stably and inexpensively. Development of a flow battery is desired.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide a redox flow battery capable of obtaining a high electromotive force.

In order to improve the electromotive force, it is conceivable to use a metal ion having a high standard redox potential as the active material. The standard redox potential of the metal ion of the positive electrode active material used in the conventional redox flow battery is 0.77 V for Fe ²⁺ / Fe ^{3+ and} 1.0 V for V ⁴⁺ / V ⁵⁺ . The present inventors are water-soluble metal ions as metal ions (active material ions) serving as a positive electrode active material, have a higher standard redox potential than conventional metal ions, are relatively cheaper than vanadium, A redox flow battery using manganese (Mn), which is considered to be excellent in terms of supply, was examined. The standard oxidation-reduction potential of Mn ²⁺ / Mn ³⁺ is 1.51 V, and Mn ions have preferable characteristics for constituting a redox pair having a larger electromotive force. In addition, the present inventors focused on titanium (Ti) as a metal ion serving as a negative electrode active material, and studied a redox flow battery using the Ti. The standard oxidation-reduction potential of Ti ⁴⁺ / Ti ³⁺ is 0 V, and this titanium also has preferable characteristics for constituting a redox pair having a higher electromotive force. In particular, a redox flow battery using Mn ions as a positive electrode active material and Ti ions as a negative electrode active material is expected as a redox flow battery capable of obtaining an unprecedented high electromotive force.

  Here, as a result of further investigation by the present inventors, in a redox flow battery using Mn ions as a positive electrode active material, or a redox flow battery using Ti ions as a negative electrode active material, charging or discharging becomes insufficient while repeating charging and discharging. It was found that it may cause insufficient discharge.

First, it was found that in a redox flow battery employing Mn ions as the positive electrode active material, the concentration distribution of Mn ions (active material ions) is biased in the positive electrode electrolyte. Since the specific gravity of Mn ³⁺ which is an oxidation state at the time of charging is larger than that of Mn ²⁺ which is an oxidation state at the time of discharge, an electrolyte solution (charged state) which has a higher Mn ³⁺ concentration than Mn ²⁺ at the lower side of the positive electrode tank There is an electrolyte solution), and the upper side tends to be a two-layer state in which there is an electrolyte solution (electrolyte in a discharge state) having a higher Mn ²⁺ concentration than Mn ³⁺ . Therefore, when adopting a configuration in which the liquid is supplied from the lower part of the positive electrode tank to the battery element, the electrolyte in the charged state is always supplied to the battery element, so that the redox flow battery can be sufficiently charged. There is a risk of disappearing. In the worst case, there is a risk of overvoltage during charging or precipitation of the active material.

On the other hand, in a redox flow battery that uses Ti ions (active material ions) as the negative electrode active material, there is a charged electrolyte on the upper side of the negative electrode tank and a discharge on the lower side, contrary to the Mn positive electrode tank. It is easy to be in a two-layer state with an electrolyte in a state. This is because the specific gravity of Ti ³⁺ which is an oxidation state at the time of charging is smaller than that of Ti ⁴⁺ which is an oxidation state at the time of discharge. In such a case, if the configuration is such that the liquid is sent to the battery element from the lower part of the negative electrode tank, the electrolyte in a discharged state is always sent to the battery element, so that the redox flow battery can be sufficiently discharged. There is a risk that it will not be possible.

  Based on the examination and knowledge described above, the present invention is defined below.

  The redox flow battery of the present invention is a redox flow battery that performs charge and discharge by supplying a positive electrode electrolyte and a negative electrode electrolyte to a battery element including a positive electrode, a negative electrode, and a diaphragm interposed between the electrodes. It has at least one of a positive electrode electrolyte containing Mn ions as a positive electrode active material and a negative electrode electrolyte containing Ti ions as a negative electrode active material. The redox flow battery of the present invention includes a stirring mechanism that stirs the electrolytic solution in a tank that stores an electrolytic solution containing Mn ions or Ti ions, and a control unit that controls the operation of the stirring mechanism. And

Here, in the redox flow battery of the present invention, the installation state of the stirring mechanism differs depending on the configuration of the positive electrode electrolyte and the negative electrode electrolyte. Specifically, there are the following three.
[1] When the positive electrode electrolyte contains Mn ions as the positive electrode active material and the negative electrode electrolyte does not contain Ti ions, the stirring mechanism is provided in a positive electrode tank that stores the positive electrode electrolyte. Of course, a stirring mechanism may also be provided in the negative electrode tank for storing the negative electrode electrolyte.
[2] When the negative electrode electrolyte contains Ti ions as the negative electrode active material and the positive electrode electrolyte does not contain Mn ions, the stirring mechanism is provided in the negative electrode tank. Of course, a stirring mechanism may also be provided in the positive electrode tank.
[3] When the positive electrode electrolyte contains Mn ions and the negative electrode electrolyte contains Ti ions, the stirring mechanism is provided in both the positive electrode tank and the negative electrode tank.

  According to the redox flow battery of the present invention having the above-described configuration, even when the distribution of active material ions in the electrolytic solution in the tank becomes non-uniform due to charging / discharging, the distribution can be made uniform quickly. The timing of stirring may be before the electrolyte solution is sent to the battery element for charging and discharging, and it is preferable to continue stirring at least until the feeding of the electrolyte solution for charging and discharging is completed. By doing so, the problem of insufficient charge or insufficient discharge in a redox flow battery using at least one of Mn ions and Ti ions as an active material can be made difficult to occur.

  Hereinafter, the preferable form of this invention redox flow battery is demonstrated.

  As one form of this invention redox flow battery, it is mentioned that a stirring mechanism is set as the structure provided with introductory piping and a gas supply mechanism. The introduction pipe is a pipe that is introduced from the outside of the tank into the tank and opens into the electrolytic solution stored in the tank. The gas supply mechanism is a mechanism for supplying an inert gas into the tank via the introduction pipe.

  According to the said structure, electrolyte solution can be stirred by bubbling electrolyte solution with an inert gas. If more efficient bubbling is performed, it is preferable to provide a plurality of pores in a portion of the side wall portion of the introduction pipe that is disposed in the electrolytic solution, as shown in a first embodiment described later.

  As one form of the redox flow battery of the present invention, the stirring mechanism includes a stirring member that rotates or swings in the electrolytic solution in the tank and stirs the electrolytic solution.

  According to the above configuration, convection can be generated in the electrolytic solution by the movement of the stirring member, and the electrolytic solution in the tank can be effectively stirred.

  As one form of the redox flow battery of the present invention including the stirring member, the stirring member may be configured to operate by electromagnetic force. In that case, as the stirring member, a permanent magnet coated with resin may be used. And it is good to rotate or vibrate this resin coat magnet by the electromagnetic force from the outside of a tank. This is the same configuration as a so-called magnetic stirrer.

  For example, when the electrolyte solution is stirred with a stirring member with a propeller at the tip of the rotating shaft, a hole is made in the tank, the rotating shaft is passed through the hole, and the gap between the hole and the rotating shaft is sealed. There is a need to. On the other hand, if it is the structure which operates an agitating member with an electromagnetic force, it is not necessary to make a hole in a tank and therefore, there is no need for sealing.

  As one form of this invention redox flow battery, it is mentioned that a stirring mechanism is set as the structure provided with piping for stirring and a liquid feeding pump. The stirring pipe is a pipe having one end opened to the liquid phase in the tank and the other end opened to the liquid phase or gas phase in the same tank. Moreover, a liquid feeding pump is a pump which sends out electrolyte solution toward the other end side from the one end side of piping for stirring.

  By setting it as the said structure, a big convection can be produced in the electrolyte solution in a tank, and the electrolyte solution in a tank can be stirred efficiently and effectively.

  As an embodiment of the redox flow battery of the present invention provided with a stirring pipe and a liquid feed pump, a temperature adjusting mechanism for adjusting the temperature of the electrolytic solution may be provided in the middle of the stirring pipe.

  Basically, in the redox flow battery of the present invention, the agitation mechanism is operated before charging / discharging. Therefore, if a temperature adjusting mechanism is provided in the middle of the stirring pipe, the electrolyte can be efficiently adjusted to a temperature suitable for charging / discharging at the time of charging / discharging of the redox flow battery. In addition, since the waste of operating the temperature adjustment mechanism when the stirring mechanism is not operated can be eliminated, the running cost of the redox flow battery can be reduced.

  As one form of this invention redox flow battery provided with the piping for stirring and a liquid feeding pump, it is mentioned to be set as the structure provided with the filter which removes the impurity and deposit in electrolyte solution in the middle of piping for stirring.

  By providing a filter in the stirring pipe, the electrolytic solution can be applied to the filter while stirring the electrolytic solution. This eliminates the need for a separate pump for feeding liquid to the filter, thereby reducing the equipment cost and running cost of the redox flow battery.

  As one embodiment of the redox flow battery of the present invention, the metal ion species contained in the positive electrode electrolyte and the negative electrode electrolyte is common, the liquid phase of the positive electrode tank storing the positive electrode electrolyte, and the negative electrode storing the negative electrode electrolyte A configuration including a liquid-phase communication pipe that communicates with the liquid phase of the tank may be mentioned. In this case, one end of the liquid phase communication pipe on the negative electrode tank side is opened at a position near the bottom of the negative electrode tank, and the other end of the liquid phase communication pipe on the positive electrode tank side is higher than the one end. And it is preferable to make it open to the position near the liquid level of the electrolyte solution in the tank for positive electrodes.

  When the metal ion species of the positive and negative electrolytes are common, that is, when an electrolyte containing Mn ions and Ti ions is used as the positive and negative electrolytes, the redox flow can be achieved by mixing both electrolytes. The battery can be quickly self-discharged to recover the battery capacity. Here, in the positive electrode tank containing Mn ions as the active material, the discharged electrolyte solution tends to be biased toward the upper side, and in the negative electrode tank containing Ti ions as the active material, the discharged electrolyte solution tends to be biased toward the lower side. . Therefore, when the positive and negative electrolytes are self-discharged, if the discharged electrolyte solution on the upper side of the positive electrode tank is mixed with the discharged electrolyte solution on the lower side of the negative electrode tank, self-discharge is caused. It can be done quickly.

  As one form of this invention redox flow battery, it is mentioned that a control means makes it the structure which operates the said stirring mechanism intermittently according to a predetermined schedule.

  It is inefficient to keep the stirring mechanism in operation at all times. On the other hand, the running cost of the redox flow battery can be reduced by operating the stirring mechanism intermittently. The reason why the stirring mechanism can be operated according to the schedule is that the operation schedule is often determined to some extent in a normal redox flow battery. For example, when a redox flow battery is provided for load leveling, the redox flow battery may be operated according to a fixed operation schedule such that it is charged at night and discharged in a time when the power demand is high during the day. Many. If the operation schedule is determined in this way, the schedule for stirring the electrolyte can be easily determined in accordance with the operation schedule.

  As one form of the redox flow battery of the present invention, a configuration including a detection mechanism for detecting a distribution state of active material ions in an electrolytic solution in a tank can be cited. In that case, the control means may control the stirring mechanism based on the detection result of the detection mechanism.

  Operate the stirring mechanism based on the detection result, that is, operate the stirring mechanism when the concentration distribution of the active material ions in the electrolyte becomes non-uniform, effectively reducing the running cost of the redox flow battery Can do. Here, as a detection mechanism, as shown in Embodiment 3 to be described later with reference to FIG. 4A, a detection mechanism that detects the concentration distribution of the active material ions by detecting the transparency (or chromaticity) of the electrolytic solution. Can be mentioned. The reason why the transparency of the electrolyte solution can be detected is that the electrolyte solution containing Mn ions and the electrolyte solution containing Ti ions can differ in transparency due to the difference in the oxidation number of ions. In addition, an electrolyte that actually samples the electrolytic solution and detects the concentration distribution of the active material ions may be employed.

  The redox flow battery of the present invention is a redox flow battery having high electromotive force and stable charge / discharge characteristics.

It is a schematic block diagram of the basic composition of the redox flow battery common to each embodiment. It is a schematic block diagram of the stirring mechanism described in Embodiment 1 which stirs the electrolyte solution in a tank by introduce | transducing an inert gas in a tank. (A)-(C) is a schematic block diagram of the stirring mechanism described in Embodiment 2 which stirs electrolyte solution by causing convection to the electrolyte solution in a tank. (A)-(B) is a schematic block diagram of the stirring mechanism described in Embodiment 3 which takes out the electrolyte solution in a tank outside once, and stirs an electrolyte solution again in a tank. It is a schematic block diagram explaining the arrangement | positioning state of the liquid phase communication pipe which connects the liquid phase of the tank for positive electrodes described in Embodiment 4, and the liquid phase of the tank for negative electrodes.

  Hereinafter, embodiments of the redox flow battery of the present invention will be described with reference to the drawings. In addition, since most of the structures with which the redox flow battery of each embodiment is provided are common, the common structure is demonstrated based on FIG. Thereafter, a configuration unique to each embodiment will be described with reference to the drawings.

<Common configuration of redox flow battery>
FIG. 1 is a schematic configuration diagram showing a portion having a common configuration in a redox flow battery (hereinafter referred to as an RF battery) 100 of each embodiment. This RF battery 100 differs from a conventional redox flow battery in that Mn ions are used as a positive electrode active material and Ti ions are used as a negative electrode active material. A solid line arrow in FIG. 1 means charging, and a broken line arrow means discharging. In addition, the active material ion shown in FIG. 1 has shown the typical form, and forms other than illustration may be included. For example, FIG. 1 shows Ti ⁴⁺ as the tetravalent Ti ions, but other forms such as TiO ²⁺ may also be included.

  The RF battery 100 in FIG. 1 typically includes electric power including an electric power generation unit (for example, a solar power generator, a wind power generator, other general power plants, etc.) and substation facilities via an AC / DC converter. It is connected to the grid, is charged using the power generation unit as a power supply source, and is discharged using the load as a power supply target. Similar to the conventional RF battery, the RF battery 100 includes a battery element 100c and a circulation mechanism (tank, piping, pump) that circulates the electrolyte in the battery element 100c.

[Battery elements and circulation mechanism]
The battery element 100c included in the RF battery 100 includes a positive electrode cell 102 including a positive electrode 104, a negative electrode cell 103 including a negative electrode 105, and a diaphragm 101 that separates the cells 102 and 103 and transmits ions. Prepare. A positive electrode tank 106 that stores a positive electrode electrolyte is connected to the positive electrode cell 102 via pipes 108 and 110. A negative electrode tank 107 for storing a negative electrode electrolyte solution is connected to the negative electrode cell 103 via pipes 109 and 111. The pipes 108 and 109 are provided with pumps 112 and 113 for circulating the electrolyte solution of each electrode. The battery element 100c uses the pipes 108 to 111 and the pumps 112 and 113 to the positive electrode cell 102 (positive electrode 104) and the negative electrode cell 103 (negative electrode 105), respectively. 107 circulates and supplies the negative electrode electrolyte, and accompanies a valence change reaction of active material ions (Mn ions for the positive electrode and Ti ions for the negative electrode) that become active materials in the electrolyte of each electrode. Charge and discharge.

  The battery element 100c is normally used in a form called a cell stack in which a plurality of battery elements are stacked. The cells 102 and 103 constituting the battery element 100c discharge a bipolar plate (not shown) in which the positive electrode 104 is disposed on one surface and the negative electrode 105 is disposed on the other surface, a liquid supply hole for supplying an electrolytic solution, and an electrolytic solution. A configuration using a cell frame having a drain hole to be formed and having a frame (not shown) formed on the outer periphery of the bipolar plate is representative. By laminating a plurality of cell frames, the liquid supply hole and the drainage hole constitute an electrolyte flow path, and the flow path is connected to the pipes 108 to 111. The cell stack is configured by repeatedly stacking a cell frame, a positive electrode 104, a diaphragm 101, a negative electrode 105, a cell frame,.

[Electrolyte]
As the positive and negative electrolytes used in the RF battery 100 of the present embodiment, a common electrolyte containing Mn ions and Ti ions is used. On the positive electrode side, Mn ions work as a positive electrode active material, and on the negative electrode side, Ti ions work as a negative electrode active material. Further, the Ti ions on the positive electrode side suppress the precipitation of MnO ₂ for unknown reasons. Each concentration of Mn ions and Ti ions is preferably 0.3M or more and 5M or less.

As in this embodiment, the following three effects can be achieved by using a common electrolytic solution for the positive and negative electrolytic solutions.
(1) It is possible to effectively avoid a phenomenon in which the battery capacity decreases due to the active material ions moving to the counter electrode through the diaphragm of the battery element and the active material ions originally reacting at each electrode relatively decreasing.
(2) Liquid transfer over time with charge / discharge (a phenomenon in which the electrolyte solution of one electrode moves to the other electrode through the diaphragm) causes variations in the amount and ion concentration of the electrolyte solution of both electrodes Even in such a case, the above-mentioned variation can be easily corrected by mixing electrolytes of both electrodes.
(3) There is no need to prepare a dedicated electrolyte separately for positive and negative, and the productivity of the electrolyte is excellent.

Solvents for the electrolyte include H ₂ SO ₄ , K ₂ SO ₄ , Na ₂ SO ₄ , H ₃ PO ₄ , H ₄ P ₂ O ₇ , K ₂ PO ₄ , Na ₃ PO ₄ , K ₃ PO ₄ , HNO ₃ , at least one aqueous solution selected from KNO ₃ and NaNO ₃ can be used.

[Others]
Although not shown, the RF battery 100 may include a monitor cell for monitoring the battery capacity. The monitor cell is basically a single cell that is smaller than the battery element 100c having the same configuration as the battery element 100c, receives positive and negative electrolytes from the positive electrode tank 106 and the negative electrode tank 107, and receives the battery element 100c. Similarly, an electromotive force is generated. The battery capacity of the RF battery 100 can be known from the open circuit voltage.

<Embodiment 1>
The RF battery 100 with reference to FIG. 1 further includes a configuration for stirring the electrolyte stored in the tanks 106 and 107 in the positive electrode tank 106 and the negative electrode tank 107. Hereinafter, the structure of the stirring mechanism of this embodiment is demonstrated based on FIG. In FIG. 2, only the positive electrode tank 106 and the stirring mechanism 1 provided in the tank 106 are illustrated. Although not specifically shown, it may be considered that the negative electrode tank 107 (see FIG. 1) is provided with the same configuration.

  The present embodiment shown in FIG. 2 includes a stirring mechanism 1 for stirring the electrolytic solution in the positive electrode tank 106 and a control mechanism 9 for controlling the stirring mechanism 1.

[Agitating mechanism]
The stirring mechanism 1 includes an introduction pipe 11 that communicates with the inside and outside of the positive electrode tank 106, and a gas supply mechanism 12 that supplies an inert gas into the positive electrode tank 106 via the introduction pipe 11. Among these configurations, the introduction pipe 11 is a pipe made of PVC, PE, fluororesin, or the like that is not easily corroded by the electrolytic solution. The introduction pipe 11 in the electrolytic solution is preferably arranged so that the electrolytic solution can be convected in the vertical direction (depth direction) of the positive electrode tank 106 by introducing an inert gas. A plurality of pores 11h are formed in the side wall of the introduction pipe 11 so that the inert gas fed from the gas supply mechanism 12 can be injected not only from the end opening of the introduction pipe 11 but also from the pores 11h. It has become. The cross-sectional shape of the introduction pipe 11 is not particularly limited, and may be, for example, a circle or a polygon.

  On the other hand, the gas supply mechanism 12 can typically be constituted by a gas cylinder that stores an inert gas and a pump that pumps the inert gas from the gas cylinder to the introduction pipe 11. As an inert gas, helium, argon, nitrogen etc. can be mentioned, for example.

[Control mechanism]
The control mechanism 9 is a mechanism that controls the supply mechanism 12 of the agitation mechanism 1 to adjust the amount of inert gas blown into the positive electrode tank 106, and can be configured by, for example, a computer. The control mechanism 9 may also serve as a computer that controls the charging / discharging operation of the RF battery 100. In addition, this control mechanism 9 is connected also to the stirring mechanism in the tank for negative electrodes, and also controls the stirring mechanism.

  The control mechanism 9 may be configured to control the operation of the stirring mechanism 1 according to a predetermined schedule. In that case, it is preferable to determine the operation schedule of the stirring mechanism 1 according to the charge / discharge schedule of the RF battery 100. For example, if the charging / discharging schedule is such that charging is performed at a specific time during the night and discharging is performed during a specific time during the day when power demand is high, the agitation mechanism 1 starts to be operated slightly before starting charging (discharging). It is preferable to control the agitation mechanism 1 according to an operation schedule in which the operation of the agitation mechanism 1 is stopped when (discharge) is finished. In addition, as illustrated in Embodiment 3 to be described later, the state of the electrolytic solution in the positive electrode tank 106 may be detected, and the stirring mechanism 1 may be controlled based on the detection result.

  According to the configuration of the first embodiment described above, the concentration of active material ions (Mn ions in the positive electrode tank 106 and Ti ions in the negative electrode tank 107) in the electrolytic solution is uniformly set when charging and discharging the RF battery 100. can do. As a result, the RF battery 100 can be operated in a healthy state.

<Embodiment 2>
In the second embodiment, unlike in the first embodiment, an RF battery 100 including a stirring mechanism that stirs the electrolytic solution by causing the electrolytic solution to convect in the vertical direction of the positive electrode tank 106 will be described with reference to FIG. 3.

  First, the stirring mechanism 2 shown in FIG. 3A includes a stirring member 21 having a propeller at the tip of a rotating shaft, and a motor 22 that rotates the rotating shaft around the axis. According to such a configuration, a very strong convection can be generated in the electrolytic solution in the positive electrode tank 106, and the electrolytic solution can be stirred quickly and effectively.

  Next, the stirring mechanism 3 shown in FIG. 3B has the same configuration as a so-called magnetic stirrer. Specifically, a stirrer bar (stirring member) 31 and a stirrer body 32 that generates an electromagnetic force for rotating the stirrer bar 31 are provided. According to such a configuration, the stirrer bar 31 can be operated without making a hole in the positive electrode tank 106. As the stirrer bar 31, a magnet whose outer periphery is covered with Teflon (registered trademark) or the like can be used. The shape of the stirrer bar 31 is not particularly limited. For example, the stirrer bar 31 may have a general bowl shape, an octagonal bar shape, or a windmill blade shape. good. Note that a magnetic stirrer that stirs the electrolyte solution by vibration instead of rotation may be used.

  Finally, the stirring mechanism 4 shown in FIG. 3C includes a submersible pump (stirring member) 41 immersed in the electrolytic solution in the positive electrode tank 106, and supplies the submersible pump 41 with electric power to And a power supply device 42 to be operated. According to this configuration, it is possible to generate stronger convection than the configuration of FIGS. 3 (A) and 3 (B).

<Embodiment 3>
In the third embodiment, unlike the first and second embodiments, the RF battery 100 including the stirring mechanism 5 that stirs the electrolytic solution by taking the electrolytic solution out of the positive electrode tank 106 and returning it to the positive electrode tank 106 again. This will be described with reference to FIG.

  As shown in FIGS. 4A and 4B, the stirring mechanism 5 includes an outward pipe (stirring pipe) 51, a return pipe (stirring pipe) 52, and a liquid feed pump 53. The forward piping 51 opens to the liquid phase of the positive electrode tank 106, and the return piping 52 opens to the gas phase (or liquid phase is acceptable) of the positive electrode tank 106. The pump 53 is provided between the pipes 51 and 52, and sends the electrolytic solution from the positive electrode tank 106 to the return pipe 52 via the forward pipe 51. In addition to the above configuration, FIG. 4A includes a configuration for confirming the distribution of Mn ions in the electrolytic solution in the positive electrode tank 106, and FIG. 4B includes a configuration for adjusting the temperature of the electrolytic solution. These configurations will be described later.

  According to the stirring mechanism 5 configured as described above, it is possible to create a flow of the electrolytic solution in which the positive electrode tank 106 → the outward piping 51 → the backward piping 52 → the positive electrode tank 106, and the electrolytic solution can be effectively stirred. .

[Configuration for confirming the distribution of Mn ions]
Since the Mn ions in the electrolyte in the positive electrode tank 106 are not always biased, it is inefficient to always operate the above configuration. Therefore, it is preferable to detect the bias and determine the necessity of stirring of the electrolytic solution based on the detection result to operate the stirring mechanism 5. For example, in the configuration shown in FIG. 4A, as a configuration for detecting the deviation, a transparent window portion 52w that can confirm the transparency of the electrolytic solution is formed in the return piping 52 (or the outgoing piping 51 is acceptable).

Here, the solution of Mn ³⁺ is colored, and the solution of Mn ²⁺ is almost colorless and transparent. If Mn ³⁺ in the electrolytic solution becomes dominant, the transparency of the electrolytic solution becomes lower. Conversely, if Mn ²⁺ becomes dominant. The transparency of the electrolyte is increased. That is, when the RF battery 100 is discharged and Mn ²⁺ should be dominant in the positive electrode tank 106, but the transparency of the electrolyte that can be confirmed from the window 52 w is low, It can be determined that there is a bias in the distribution of Mn ions in the electrolyte. Here, also in the negative electrode tank 107 (see FIG. 1), the necessity for stirring of the electrolytic solution can be determined from the transparency of the electrolytic solution by a configuration similar to the configuration of FIG. This is because the transparency of the electrolytic solution is lowered when Ti ³⁺ is dominant in the electrolytic solution, and the transparency of the electrolytic solution is increased when Ti ⁴⁺ is dominant.

  Confirmation of the transparency of the electrolytic solution may be confirmed visually or, for example, automatically by an optical sensor. In the former case, it is preferable that the operator confirms the transparency of the electrolytic solution with the naked eye and operates the control mechanism 9 to adjust the output of the pump 53. In the latter case, the control mechanism 9 may automatically adjust the output of the pump 53 based on the detection result of the optical sensor.

  In addition, the structure which detects the bias | inclination of the Mn ion of the electrolyte solution using the window part 52w is not necessarily limited to the return piping 52 and the outward piping 51. FIG. For example, the window portion may be formed at a position near the bottom of the positive electrode tank 106, the window portion may be formed at a position near the liquid surface of the electrolytic solution in the positive electrode tank 106, or both You may form a window part in a position. When provided in the positive electrode tank 106, the present invention can be applied to the configurations of the first and second embodiments.

  In addition to the configuration referring to the transparency of the electrolytic solution, a configuration in which the electrolytic solution is taken out from the positive electrode tank 106 and the bias of Mn ions in the electrolytic solution is detected may be employed. For example, when the electrolytic solution is taken out into a separate container from the position near the bottom of the positive electrode tank 106 and the position near the liquid level, and the potential difference between the electrolytic solutions exceeds a threshold value, stirring of the electrolytic solution is necessary. The structure which judges that can be mentioned.

[Configuration to adjust the temperature of the electrolyte]
In FIG. 4B, a temperature adjustment mechanism 8 for adjusting the temperature of the electrolytic solution, for example, a heat exchanger, is provided in the return pipe 52 (or the outgoing pipe 51 is also acceptable). According to this structure, when stirring electrolyte solution, the temperature of electrolyte solution can be adjusted simultaneously. In the first place, in the configuration of the present invention, the electrolyte solution is agitated before charging / discharging of the RF battery 100. Therefore, it is efficient to adjust the temperature of the electrolyte solution at that time.

[Others]
A filter for removing impurities and precipitates in the electrolytic solution may be provided inside the stirring pipes 51 and 52. By providing the filter, the load on the liquid feeding pump 53 can be reduced. As the material of the filter, for example, a plastic (PVC, PE, fluororesin, etc.) mesh that is not corroded by the electrolyte, a carbon mesh, or the like can be used. Moreover, it is preferable that the hole diameter of a filter shall be 0.1-100 micrometers.

<Embodiment 4>
In the fourth embodiment, based on FIG. 5, the RF battery 100 including the liquid phase communication pipe 7 that further communicates the liquid phase of the positive electrode tank 106 and the liquid phase of the negative electrode tank 107 to the configuration of the first to third embodiments. explain. FIG. 5 is a simple drawing showing only the connection state of the positive electrode tank 106, the negative electrode tank 107 and the liquid phase communication pipe 7.

[Liquid phase communication pipe]
The liquid phase communication pipe 7 is a pipe that communicates the liquid phase of the positive electrode tank 106 and the liquid phase of the negative electrode tank 107. More specifically, one end of the liquid phase communication pipe 7 on the negative electrode tank 107 side opens at a position near the bottom of the negative electrode tank 107 and the other end of the liquid phase communication pipe 7 on the positive electrode tank 106 side. Is open at a position higher than the one end and near the liquid level of the electrolytic solution in the positive electrode tank 106. By providing the liquid phase communication pipe 7, the electrolytic solution in both tanks 106 and 107 can be mixed. Further, a valve 7b is formed in the middle of the liquid phase communication pipe 7, so that the connection between the positive electrode tank 106 and the negative electrode tank 107 can be switched as necessary.

The liquid phase communication pipe 7 is provided to recover the battery capacity of the RF battery 100. By opening the liquid phase communication tube 7, the positive and negative electrolytes are mixed together, and the RF battery 100 is quickly discharged. Here, as already described, in the positive electrode tank 106, Mn ^{2+ in} the oxidized state at the time of discharge is biased to the upper layer side of the tank 106, and in the negative electrode tank 107, Ti which is in the oxidized state at the time of discharge. ⁴⁺ is biased toward the lower layer side of the tank 107. Therefore, the liquid phase communication pipe 7 that connects the upper side of the positive electrode tank 106 and the lower side of the negative electrode tank 107 is more efficient and more reliable than the liquid phase communication pipe that simply connects the tanks 106 and 107 horizontally. The battery 100 can be discharged. If the stirring mechanism is operated after the liquid phase communication tube 7 is opened and a predetermined time has elapsed, the RF battery 100 can be more reliably discharged.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably and can implement. For example, the composition of the positive electrode electrolyte and the negative electrode electrolyte may be different. When the positive electrode electrolyte contains Mn ions and the negative electrode electrolyte does not contain Ti ions, the configuration described in the embodiment may be provided only in the positive electrode tank. Moreover, what is necessary is just to provide the structure demonstrated by embodiment only to the tank for negative electrodes, when a negative electrode electrolyte solution contains Ti ion and a positive electrode electrolyte solution does not contain Mn ion.

  The redox flow battery of the present invention has a large capacity for the purpose of stabilizing fluctuations in power generation output, storing electricity when surplus of generated power, load leveling, etc., for power generation of new energy such as solar power generation and wind power generation. It can utilize suitably for a storage battery. In addition, the redox flow battery of the present invention can be suitably used as a large-capacity storage battery that is installed in a general power plant or factory, for the purpose of instantaneous voltage drop / power failure countermeasures and load leveling.

DESCRIPTION OF SYMBOLS 100 Redox flow battery 100c Battery element 101 Diaphragm 102 Positive electrode cell 103 Negative electrode cell 104 Positive electrode 105 Negative electrode 106 Positive electrode tank 107 Negative electrode tank 108,109,110,111 Piping 112,113 Pump 1 Stirring mechanism 11 Introducing piping 11h Pore 12 Gas supply mechanism 2 Stirring mechanism 21 Rotating shaft (stirring member) 22 Motor 3 Stirring mechanism 31 Stirrer bar (stirring member) 32 Stirrer body 4 Stirring mechanism 41 Submersible pump (stirring member) 42 Power supply device 5 Stirring mechanism 51, 52 For stirring Piping 53 Liquid feed pump 52w Window 7 Liquid phase communication pipe 7b Valve 8 Temperature adjustment mechanism 9 Control mechanism

Claims (10)

A redox flow battery for charging and discharging by supplying a positive electrode electrolyte and a negative electrode electrolyte to a battery element comprising a positive electrode, a negative electrode, and a diaphragm interposed between the electrodes,
Having at least one of a positive electrode electrolyte containing Mn ions as a positive electrode active material and a negative electrode electrolyte containing Ti ions as a negative electrode active material;
An agitation mechanism for agitating the electrolyte in a tank storing an electrolyte containing Mn ions or Ti ions;
Control means for controlling the operation of the stirring mechanism;
A redox flow battery comprising: The stirring mechanism is
An introduction pipe that is introduced into the tank from outside the tank and opens into the electrolyte stored in the tank;
A gas supply mechanism for supplying an inert gas into the tank via the introduction pipe;
The redox flow battery according to claim 1, comprising:   The redox flow battery according to claim 1, wherein the stirring mechanism includes a stirring member that rotates or swings in the electrolytic solution in the tank to stir the electrolytic solution.   The redox flow battery according to claim 3, wherein the stirring member is operated by electromagnetic force. The stirring mechanism is
One end is opened to the liquid phase in the tank, and the other end is opened to the liquid phase or gas phase in the same tank;
A liquid feed pump for sending out an electrolyte solution from the one end side toward the other end side;
The redox flow battery according to claim 1, comprising:   The redox flow battery according to claim 5, further comprising a temperature adjustment mechanism that is provided in the middle of the stirring pipe and adjusts the temperature of the electrolytic solution.   The redox flow battery according to claim 5 or 6, further comprising a filter provided in the middle of the agitation pipe to remove impurities and precipitates in the electrolytic solution. The metal ion species contained in the positive electrode electrolyte and the negative electrode electrolyte are common,
A liquid phase communication pipe that communicates the liquid phase of the positive electrode tank storing the positive electrode electrolyte and the liquid phase of the negative electrode tank storing the negative electrode electrolyte;
One end of the liquid phase communication pipe on the negative electrode tank side opens at a position near the bottom of the negative electrode tank,
The other end of the liquid phase communication pipe on the positive electrode tank side is open at a position higher than the one end and near the liquid surface of the electrolyte in the positive electrode tank. Item 8. The redox flow battery according to any one of Items 1 to 7.   The redox flow battery according to any one of claims 1 to 8, wherein the control unit intermittently operates the stirring mechanism according to a predetermined schedule. A detection mechanism for detecting the distribution state of active material ions in the electrolyte in the tank,
The redox flow battery according to any one of claims 1 to 8, wherein the control unit controls the agitation mechanism based on a detection result of the detection mechanism.

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