Secondary battery system

Abstract

To provide a secondary battery system capable of reducing a power supply cost by reducing a power value required in a power supply for supplying a current to a charging part.SOLUTION: A secondary battery system includes a charging module 300 having a plurality of charging units 301, a first current path 320 for connecting the charging module 300 to a first power supply 310, and a switching device 330 arranged in the first current path 320 and capable of changing a connection destination of the charging unit 301 to the first power supply 310. The first current path 320 causes the first power supply 310 to selectively supply a current to each charging unit 301 by the switching device 330 switching the connection destination of the charging unit 301.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a secondary battery system. [Background technology]

[0002] In a charging section of a secondary battery, a current is supplied from a power supply unit to the charging section during charging operation (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4501055 [Patent Document 2] U.S. Patent No. 7,470,351 Summary of the Invention [Problem to be solved by the invention]

[0004] In supplying current to a charging unit, the cost of the power supply unit (power supply cost) increases as the required power value increases.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a secondary battery system that can reduce the power value required in a power source that supplies current to a charging section, thereby reducing power source costs. [Means for solving the problem]

[0006] In order to solve the above problems, the secondary battery system of the present disclosure comprises a charging section module having a plurality of charging units, a first current path connecting the charging section module to a first power source, and a switching device disposed within the first current path that enables the connection destination of the charging units to be changed relative to the first power source, and the first current path is characterized in that the switching device switches the connection destination of the charging units, thereby selectively supplying current from the first power source to each of the charging units.

[0007] In the secondary battery system, the charging section module may be configured as a charging section for a flow-type metal-air battery.

[0008] In the secondary battery system, the switching device may periodically switch the connection destination of the charging unit.

[0009] Moreover, in the secondary battery system, the switching device can be configured to be able to connect any one of the charging units to the first power source.

[0010] In the secondary battery system, the switching device may be configured to be able to change the number of the charging units that can be connected to the first power source.

[0011] In the secondary battery system, the switching device may be a group of switches disposed between the secondary battery system and the charging unit.

[0012] In the secondary battery system, the first current path may be configured to connect a plurality of the charging units in series.

[0013] In the secondary battery system, the first current path may be configured to connect a plurality of the charging units in parallel.

[0014] Furthermore, in the secondary battery system, the multiple charging units can be connected to each other by a negative electrode slurry path and an electrolyte path, and the negative electrode slurry can flow through the negative electrode slurry path and the electrolyte can flow through the electrolyte path.

[0015] In the secondary battery system, the plurality of charging units may be configured such that the negative electrode slurry path and the electrolyte path are connected in series.

[0016] In addition, the secondary battery system may further have a second current path that connects the charging module to a second power source, and the second current path may be configured to supply current from the second power source to the plurality of charging units as a whole. [Effects of the Invention]

[0017] The secondary battery system of the present disclosure has the advantage of reducing the required power value and power supply costs by selectively supplying current to each charging unit using a switching device, compared to supplying current to the entire charging module. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is an explanatory diagram schematically illustrating the general configuration of a flow-type metal-air battery. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a battery cell in a charging section. [Figure 3] FIG. 2 is an exploded perspective view illustrating an example of the configuration of a battery stack applied to a charging unit. [Figure 4] FIG. 2 is a schematic diagram showing a configuration for supplying current to a charging part in the flow-type metal-air battery system of the first embodiment. [Figure 5] FIG. 10 is a schematic diagram showing a configuration for supplying current to a charging part in a flow-type metal-air battery system according to a second embodiment. [Figure 6] FIG. 10 is a schematic diagram showing the configuration of a negative electrode slurry path to a charging section module in a flow-type metal-air battery system according to a third embodiment. [Figure 7] FIG. 10 is a schematic diagram showing the configuration of a negative electrode slurry path to a charging section module in a flow-type metal-air battery system according to a fourth embodiment. [Figure 8] FIG. 10 is a schematic diagram showing a configuration for supplying current to a charging part in a flow-type metal-air battery system according to a fifth embodiment. [Figure 9]FIG. 11 is a schematic diagram showing another configuration for supplying current to a charging part in a flow-type metal-air battery system according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] A secondary battery system according to an embodiment of the present disclosure will be described with reference to the drawings. In the following description, a flow-type metal-air battery will be exemplified as the secondary battery. However, as will be described in detail later, the secondary battery used in the secondary battery system of the present disclosure is not limited to a flow-type metal-air battery.

[0020] (Flow-type metal-air battery) 1 is an explanatory diagram showing a schematic configuration of a flow-type metal-air battery 1 according to the present disclosure. Note that components common to multiple embodiments described below are designated by common reference numerals, and redundant explanations will be omitted.

[0021] As shown in FIG. 1, the flow-type metal-air battery 1 includes a storage unit 11, a power generation unit 12, and a charging unit 13. The flow-type metal-air battery 1 takes in air and generates (discharges) electricity using the air taken in by the power generation unit 12. The charging unit 13 is responsible for charging and discharges oxygen. Anode slurry, which is a slurry-like fluid containing anode active material and an electrolyte, is supplied from the storage unit 11 to the power generation unit 12. A pipe is connected from the storage unit 11 to the power generation unit 12, and the anode slurry can be pressure-fed via a pump or the like (not shown). The same can be done between the charging unit 13 and the storage unit 11.

[0022] The storage unit 11 stores the negative electrode slurry. The negative electrode active material contained in the negative electrode slurry includes negative electrode active material ions dissolved in the electrolyte and solid active material that has exceeded its saturated solubility in the electrolyte and is suspended in a particle state without dissolving. The solid active material also includes a reduced solid active material (metal active material) and an oxidized solid active material.

[0023] The negative electrode active material is a metal species. Examples of the metal species include zinc species, cadmium species, lithium species, sodium species, magnesium species, lead species, tin species, aluminum species, and iron species. The metal constituting the metal species may be a metal consisting of only the main component metal, or may be an alloy of the main component metal and a subcomponent. The metal species can be either a metal or an oxide. Whether the metal species becomes a metal or an oxide depends on the degree of progress of the discharge reaction or the charge reaction. However, in the discharge reaction described below, the metal species is preferably in a reduced state.

[0024] In this embodiment, the metal species is a zinc species, and the flow-type metal-air battery 1 is a flow-type zinc-air battery. The metal constituting the zinc species may be, for example, a metal consisting only of zinc as the main component, or may be an alloy of zinc as the main component and a subcomponent. When the metal species is zinc, the negative electrode active material ions dissolved in the electrolyte are zincate ions, the reduced solid active material is zinc, and the oxidized solid active material is, for example, zinc oxide.

[0025] The average particle size of the metal species is several μm when it is an oxidized solid active material (e.g., ZnO), and is several tens of μm to 200 μm when it is a reduced solid active material (e.g., Zn). The average particle size can be measured using a particle size distribution analyzer. The particle size distribution analyzer measures the particle size distribution by, for example, laser diffraction or dynamic light scattering, and calculates the median diameter D50 from the measured particle size distribution as the average particle size.

[0026] The electrolyte is selected depending on the metal species. When the metal species is zinc, the electrolyte is an alkaline aqueous solution, such as a potassium hydroxide aqueous solution or a sodium hydroxide aqueous solution. When the metal species is lithium, the electrolyte is a non-aqueous electrolyte. When the metal species is magnesium, the electrolyte is a neutral aqueous solution, such as a sodium chloride aqueous solution.

[0027] Power generation unit 12 supplies the negative electrode slurry from storage unit 11 to the negative electrode, and supplies air to the positive electrode. In power generation unit 12, a region where the negative electrode is provided and a region where the positive electrode is provided are separated by separator 130.

[0028] In the case of a flow-type zinc-air battery in which the metal species is zinc, the reaction at the negative electrode of the power generation unit 12 follows formulas (1) and (2). At the negative electrode, the reduced zinc active material reacts with hydroxide ions to generate zincate ions and release electrons. The zincate ions generate zinc oxide, water, and hydroxide ions.

[0029] Zn+4OH-→Zn(OH)42-+2e- …(1) Zn(OH)42-→ZnO+H2O+2OH- …(2) The reaction at the positive electrode of the power generation unit 12 follows formula (3): At the positive electrode, electrons are received and hydroxide ions are produced from oxygen and water.

[0030] O2 + 2H2O + 4e- → 4OH- … (3) In power generation unit 12, zinc, which is a reduced solid active material, is used for discharge. A negative electrode slurry containing a negative electrode active material is supplied to power generation unit 12 from storage unit 11. The solid active material supplied to power generation unit 12 and stored in storage unit 11 is preferably in a reduced state, or preferably there is more reduced solid active material than oxidized solid active material.

[0031] In charging section 13, negative electrode slurry is supplied to the negative electrode from storage section 11. In charging section 13, a separator 130 separates an area where the negative electrode is provided from an area where the positive electrode is provided.

[0032] When the metal species is zinc, the reactions at the negative electrode of charging unit 13 follow formulas (4) and (5). At the negative electrode, zinc oxide, which is a solid active material in an oxidized state, first reacts with water and hydroxide ions to generate zincate ions. Then, the zincate ions accept electrons to generate zinc and hydroxide ions.

[0033] ZnO+H2O+2OH-→Zn(OH)42- …(4) Zn(OH)42-+2e-→Zn+4OH- …(5) The reaction at the positive electrode of charging unit 13 follows formula (6): At the positive electrode, oxygen and water are produced from hydroxide ions, and electrons are released.

[0034] 4OH- → O2 + 2H2O + 4e- … (6) In the charging unit 13, charging is performed using zinc oxide, which is a solid active material in an oxidized state (zinc is regenerated). A negative electrode slurry containing a negative electrode active material is supplied to the charging unit 13 from the storage unit 11. The solid active material supplied to the charging unit 13 and stored in the storage unit 11 is preferably in an oxidized state, or preferably there is more oxidized solid active material than reduced solid active material.

[0035] (battery cell) FIG. 2 is a cross-sectional view that schematically shows the battery cell 100 in the charging section 13 of the flow-type metal-air battery 1 according to the embodiment.

[0036] In the flow-type metal-air battery 1, the charging section 13 is basically constituted by a battery cell 100 including a positive electrode chamber 110, a negative electrode chamber 120, and a separator 130 that separates them. The battery cell 100 circulates negative electrode slurry A through a negative electrode flow path 122, which will be described later.

[0037] The positive electrode chamber 110 includes a positive electrode 111 where an oxygen evolution reaction occurs, and water or electrolyte B is passed through the positive electrode chamber 110. The positive electrode flow path 112 is, for example, a rectangular parallelepiped-shaped space, and is a flow path through which oxygen, which is the product, flows together with water or electrolyte. In the example of FIG. 2, the positive electrode 111 is arranged so as to form part of the wall surface of the positive electrode flow path 112 that faces the separator 130. A positive electrode current-carrying plate 113 may be provided in the positive electrode chamber 110 along the positive electrode 111. Alternatively, the positive electrode chamber 110 is not limited to a configuration including the positive electrode 111 and the positive electrode current-carrying plate 113, and these may be formed as a single member.

[0038] The negative electrode chamber 120 contains a negative electrode 121 where a reduction reaction of zincate ions occurs. Inside the negative electrode chamber 120, a negative electrode flow path 122 is provided through which a negative electrode slurry A containing at least a metal active material and an electrolyte flows.

[0039] The negative electrode 121 constitutes part of the wall surface of the negative electrode flow path 122. A negative electrode current-carrying plate 123 may be provided in the negative electrode chamber 120 along the negative electrode 121. The negative electrode chamber 120 is not limited to a configuration including the negative electrode 121 and the negative electrode current-carrying plate 123, and these may be configured as a single member.

[0040] For the positive electrode 111, metals such as foamed nickel, spinel-based conductive oxides containing nickel and cobalt, and perovskite-based conductive oxides can be used. Water, the reactant of the positive electrode reaction, is preferably supplied as an electrolyte containing potassium hydroxide, which has ion conductivity. During the charging reaction of a zinc-air battery, non-uniform current distribution in the zinc electrodeposition reaction at the negative electrode can cause zinc to deposit in a dendritic (dendrite-like) state, penetrating the separator between the positive and negative electrodes and causing a short circuit with the positive electrode. For this reason, it is preferable to use a separator 130 between the positive and negative electrodes that has good ion conductivity and dendrite resistance. For the negative electrode 121, a conductive material composed of a carbon material and resin can be used.

[0041] (battery stack) FIG. 3 is an exploded perspective view illustrating an example of the configuration of a battery stack 200 that can be applied to the charging unit 13. As shown in FIG.

[0042] The battery stack 200 in Fig. 3 is configured by continuously stacking a current-carrying plate 210, a negative electrode 121, a negative electrode flow plate 220, a separator 130, a positive electrode flow plate 230, and a positive electrode 111. More specifically, one battery cell 100 is formed by a stacked structure in which one negative electrode 121, one negative electrode flow plate 220, one separator 130, one positive electrode flow plate 230, and one positive electrode 111 are sandwiched between two current-carrying plates 210. In the configuration in Fig. 3, the current-carrying plate 210 also serves as the negative electrode current-carrying plate 123 and the positive electrode current-carrying plate 113 in the battery cell 100. Although Fig. 3 corresponds to two battery cells 100, a battery stack 200 including more battery cells 100 can be formed by increasing the number of stacked structures. In addition, the battery stack 200 in FIG. 3 also uses sealing parts for fixing the negative electrode 121, the separator 130, the positive electrode 111, etc., but these sealing parts are not shown in the drawing.

[0043] The negative electrode flow path plate 220 has openings 221 that form the negative electrode flow path 122, and further has through grooves 222 formed in two opposing corners, and through holes 223 formed in the other two opposing corners. The through grooves 222 are connected to the openings 221. The positive electrode flow path plate 230 has openings 231 that form the positive electrode flow path 112, and further has through grooves 232 formed in two opposing corners, and through holes 233 formed in the other two opposing corners. The through grooves 232 are connected to the openings 231. The two corners of the positive electrode flow path plate 230 where the through grooves 232 are formed correspond to the two corners of the negative electrode flow path plate 220 where the through holes 223 are formed. The two corners of the positive electrode flow path plate 230 where the through holes 233 are formed correspond to the two corners of the negative electrode flow path plate 220 where the through grooves 222 are formed.

[0044] Meanwhile, through holes are formed in the four corners of the current-carrying plate 210 (and the sealing portion) at positions facing the through grooves and through holes of the negative electrode flow path plate 220 and the positive electrode flow path plate 230. In the battery stack 200 of Fig. 3, these through holes and through grooves communicate in the stacking direction, thereby forming manifolds for supplying negative electrode slurry A and electrolytic solution B to each battery cell.

[0045] (Flow-type metal-air battery system) [First embodiment] In the flow-type metal-air battery 1, current is supplied from a power source to the charging unit 13 during charging operation. The flow-type metal-air battery system (secondary battery system: hereinafter, referred to as the present system) of the present disclosure is a system for supplying current to the charging unit 13. Fig. 4 is a schematic diagram showing the configuration for supplying current to the charging unit 13 in the present system of the first embodiment.

[0046] As shown in Fig. 4, the charging section 13 in this system is provided as a charging section module 300 including a plurality of charging units 301A to 301D (referred to as charging units 301 when no particular distinction is made). The charging unit 301 includes at least one charging cell 302. In this embodiment, the above-described battery stack 200 can be used as the charging unit 301 (the above-described battery cell 100 serves as the charging cell 302). The number of charging units 301 included in the charging section module 300 and the number of charging cells 302 included in each charging unit 301 are not particularly limited. However, it is preferable that the number of charging cells 302 included in all charging units 301 is the same.

[0047] The system further includes a first power source 310, a first current path 320, a switching device 330, and a control circuit 340. The first power source 310 supplies current to the charging section module 300. The first current path 320 electrically connects the charging section module 300 to the first power source 310. In this embodiment, the first current path 320 connects multiple charging section modules 300 in series. The switching device 330 is disposed in the first current path 320 and can change the connection destination of the charging unit 301 with respect to the first power source 310. That is, the switching device 330 includes four switches (switch groups) disposed in parallel (corresponding to the number of charging units 301), and can change the connection destination of the charging unit 301 with respect to the first power source 310 by controlling the switching of these switches. The control circuit 340 controls the switching of the switching device 330. The control circuit 340 performs overall control of the present system, and may perform other controls in addition to switching control of the switching device 330 (for example, operation control of the pump provided in the flow-type metal-air battery 1, or output control of the first power source 310). Note that, although the present embodiment illustrates a configuration in which the first power source 310 is included in the present system, the first power source 310 may be connected externally to the present system. In other words, it is not essential that the present system include the first power source 310.

[0048] The control circuit 340 includes a microcontroller and peripheral circuits. The microcontroller includes a processor and memory. The processor executes a program stored in the memory to cause the microcontroller and peripheral circuits to operate as the control unit and power supply control unit described above. All or part of the processing performed by the microcontroller may be performed by a dedicated electronic circuit.

[0049] In this system, switching device 330 switches the connection destination of charging unit 301, thereby allowing current to be selectively supplied from first power source 310 to each charging unit 301. For example, if one of the switches in switching device 330 is turned on and the other three are turned off, current is supplied only to the charging unit 301 corresponding to the switch that is turned on (for example, if only the leftmost switch is turned on, current is supplied only to charging unit 301A).

[0050] In this system, the switching device 330 changes the connection destination of the charging unit 301 relative to the first power source 310, enabling selective current supply to each charging unit 301. This allows current to be supplied sequentially and individually to the multiple charging units 301 included in the charging module 300. Current can be supplied intermittently and periodically to each charging unit 301. For example, by turning on the switches in the switching device 330 in rotation, current can be supplied to the charging units 301A to 301D in rotation. In this way, by selectively supplying current to each charging unit 301, the system reduces the required power (output power of the first power source 310) compared to supplying current to the entire charging module 300 (to all charging units 301 simultaneously), thereby reducing the cost of the first power source 310. Furthermore, compared to supplying current to the entire charging module 300, ohmic loss can be reduced, preventing a decrease in charging efficiency. The functions and effects of this embodiment are not limited to the case where the system uses the flow-type metal-air battery 1, but can also be applied to the case where other general secondary batteries are used. That is, the effects of this embodiment can be obtained as long as the charging module 300 is equipped with a plurality of charging units 301 and can selectively supply current to each charging unit 301. General secondary batteries to which this system can be applied include lead-acid batteries, nickel-metal hydride batteries, lithium-ion batteries, NAS (sodium-sulfur) batteries, sodium-ion batteries, and redox flow batteries.

[0051] Furthermore, the current supply control in this system is not limited to selectively supplying current to one charging unit 301, but can also selectively supply current to any number of charging units 301. For example, in the configuration shown in Fig. 4, if two of the four switches included in switching device 330 are turned on, current can be selectively supplied to two charging units 301, and if three switches are turned on, current can be selectively supplied to three charging units 301. Of course, if all the switches included in switching device 330 are turned on simultaneously, current can also be supplied to all charging units 301 simultaneously.

[0052] Controlling current supply selectively to one charging unit 301 can minimize the current supplied by the first power source 310, thereby improving the cost reduction effect of the first power source 310. On the other hand, controlling current supply selectively to any number of charging units 301 is suitable when renewable energy (e.g., solar cells) with fluctuating power amounts is used as the first power source 310. In this case, it is possible to distribute the amount of power in accordance with the fluctuating power of the first power source 310, such that when the amount of power is small, current is supplied to a small number of charging units 301, and when the amount of power is large, current is supplied to a larger number of charging units 301. In this control, the control circuit 340 detects the amount of power in the first power source 310 and determines the number of charging units 301 to distribute power to according to the detected amount of power of the first power source 310.

[0053] Second Embodiment FIG. 5 is a schematic diagram showing a configuration for supplying current to the charging section 13 (charging section module 300) in the system of the second embodiment.

[0054] 5, in this embodiment, the first current path 320 connects multiple charging section modules 300 in parallel. Even when multiple charging section modules 300 are connected in parallel in this way, the switching device 330 switches the connection destination of the charging unit 301, so that current can be selectively supplied from the first power source 310 to each charging unit 301. In other words, by selectively supplying current to each charging unit 301, in this system, the required power value (output power value of the first power source 310) is smaller than when current is supplied to all of the charging section modules 300, and the cost of the first power source 310 can be reduced.

[0055] Furthermore, when multiple charging module 300 are connected in parallel, it is possible to reduce uneven reactions (caused by differences in charging efficiency due to differences in ohmic resistance) among the charging units 301 compared to when current is supplied to all of the charging module 300, thereby improving the life of the charging module 300. In this embodiment as well, the secondary battery used in this system is not limited to the flow-type metal-air battery 1, and other general secondary batteries can also be used.

[0056] Third Embodiment In this embodiment, it is assumed that the secondary battery used in this system is a flow-type metal-air battery 1. As described above, the flow-type metal-air battery 1 circulates anode slurry through the anode flow path 122 and electrolyte through the cathode flow path 112. When a current is supplied to the charging module 300 to charge the flow-type metal-air battery 1 and reactions occur at the anode 121 and the cathode 111, a metal (e.g., zinc) serving as the anode active material is generated at the anode 121 as a reaction product, and oxygen is generated at the cathode 111. At this time, metal precipitates at the anode 121, and it is necessary to peel the precipitated metal from the anode 121 and discharge it from the charging cell 302 at an appropriate timing.

[0057] Patent Document 2 discloses a technique for mechanically peeling off and discharging metal deposited on the negative electrode using a movable means such as a scraper. In contrast, the applicant of the present application has filed prior applications such as Patent Application Nos. 2023-147253 and 2023-147254, which describe methods for peeling off and discharging deposited metal during charging without using a movable means (deposited metal peeling operation) (both applications were unpublished at the time of filing this application).

[0058] The metal deposit peeling operation in the above-mentioned prior application utilizes the drag force that the negative electrode liquid (electrolyte contained in the negative electrode slurry) exerts on the metal deposit (reduced negative electrode active material particles) deposited on the negative electrode. Specifically, the viscosity of the negative electrode liquid is set to be higher than the viscosity of the positive electrode liquid (electrolyte flowing in the positive electrode chamber). In this case, the viscosity of the positive electrode liquid is, for example, 1 mPasec or more and 9 mPasec or less, and preferably 2 mPasec or more and 3 mPasec or less. The viscosity of the negative electrode liquid is, for example, 100 mPasec or more and 2000 mPasec or less, and preferably 200 mPasec or more and 500 mPasec or less.

[0059] When the positive electrode liquid has low viscosity, the turbulence of the positive electrode liquid promotes the growth of oxygen gas bubbles, which makes it easier to separate the oxygen gas from the positive electrode liquid and discharge the separated oxygen gas from the charging cell (battery cell 100), thereby increasing the charging efficiency of the charging cell.

[0060] When the negative electrode liquid has a high viscosity, the negative electrode liquid exerts a large drag force on the deposited metal, which makes it easier to peel the deposited metal from the negative electrode and discharge the peeled deposited metal from the charged cell. It also makes it easier to prevent the peeled deposited metal from settling due to gravity.

[0061] The drag force exerted by the anode liquid on the deposited metal increases as the particle size of the deposited metal, i.e., the reduced anode active material particles, increases. For this reason, the prior application proposes that the deposited metal be stripped and discharged when the particle size of the reduced anode active material particles increases (creating a cycle of growth and stripping of the deposited metal). Specifically, the flow rate of the anode liquid is periodically varied to strip the deposited metal when the particle size of the reduced anode active material particles increases, or the supply current is periodically reduced (or stopped) (to prevent growth of the anode active material particles during the stripping of the deposited metal).

[0062] In the control of periodically varying the flow rate of the negative electrode liquid, the negative electrode active material particles are grown during a period when the flow rate is slow, and then the grown negative electrode active material particles are peeled off during a period when the flow rate is fast. Note that the flow rate of the negative electrode liquid can be controlled, for example, by using the control circuit 340 to control the output of a pump that pressure-feeds the negative electrode slurry from the storage unit 11 to the charging unit 13.

[0063] In the control of periodically reducing the supply current, the negative electrode active material particles are grown during a period when the supply current is large, and when the growth of the negative electrode active material particles progresses to a certain extent, peeling of the negative electrode active material particles occurs. Therefore, the supply current is reduced (or stopped) at the timing (period) when peeling of the negative electrode active material particles is deemed to occur. The control of the supply current to the charging section module 300 can be performed, for example, by controlling the output of the first power source 310 using the control circuit 340.

[0064] It is also possible to combine control that varies the flow rate of the negative electrode liquid with control that reduces the supply current, in which case the supply current is reduced (or stopped) during periods when the flow rate is high.

[0065] 6 is a schematic diagram showing the configuration of a flow path (negative electrode slurry path) of negative electrode slurry to the charging unit module 300 in the present system of the third embodiment. Although omitted in FIG. 6, the flow type metal-air battery 1 of this system has a flow path (electrolyte solution path) of the electrolyte solution with a similar configuration.

[0066] 6, the flow-type metal-air battery 1 has an anode slurry path 400 that circulates the anode slurry between the storage unit 11 and the charging unit module 300. In this embodiment, the anode slurry path 400 connects a plurality of charging units 301 in series. Note that the series connection here refers to a connection state in which the path outlet of the n-th charging unit 301 and the path inlet of the (n+1)-th charging unit 301 are connected in the flow direction of the anode slurry.

[0067] When the negative electrode slurry path 400 connects multiple charging units 301 in series, supplying current to the entire charging module 300 during the above-described metal deposit peeling operation causes metal deposits to peel off and be discharged simultaneously in all charging units 301. As a result, the metal deposits peeled off downstream of the path in the charging module 300 become excessive, hindering the supply of negative electrode slurry to the negative electrode 121 (i.e., hindering the battery reaction). Furthermore, even during normal charging operation, oxygen generated on the positive electrode side becomes excessive downstream of the electrolyte path, hindering the supply of electrolyte to the positive electrode 111 (i.e., hindering the battery reaction). As a result, ohmic loss in the charging module 300 increases, resulting in problems such as reduced charging efficiency.

[0068] In contrast, if the current supply control of the present disclosure is adopted and current is selectively supplied from the first power source 310 to each charging unit 301, the reaction products of metal and oxygen will be generated only in the charging unit 301 receiving the current supply, and it is possible to prevent the reaction products from becoming excessive downstream of the path. This not only provides the effects of reducing power supply costs and improving charging efficiency by reducing ohmic loss, as described in the first and second embodiments, but also enables stable metal discharge.

[0069] [Fourth embodiment] In this embodiment as well, it is assumed that the secondary battery used in this system is a flow-type metal-air battery 1. FIG. 7 is a schematic diagram showing the configuration of a flow path (negative electrode slurry path) for negative electrode slurry to the charging module 300 in this system of the fourth embodiment. Although not shown in FIG. 7, the flow-type metal-air battery 1 of this system has a flow path (electrolyte path) for electrolyte solution with a similar configuration. In this embodiment, the negative electrode slurry path 400 connects multiple charging units 301 in parallel. Note that the parallel connection here refers to a connection state in which the path inlets of all the charging units 301 are connected to each other and the path outlets of all the charging units 301 are connected to each other.

[0070] When the negative electrode slurry path 400 or the electrolyte path connects multiple charging units 301 in parallel, supplying current to the entire charging module 300 will result in excess current downstream of the negative electrode slurry path 400 and the electrolyte path (i.e., the path on the discharge side relative to the charging unit 301). This will hinder the supply of negative electrode slurry and electrolyte to the charging unit 301 further downstream, causing the battery reaction to become non-uniform and reducing charging efficiency.

[0071] Therefore, even when the negative electrode slurry path 400 and the electrolyte path connect multiple charging units 301 in parallel, the current supply control of the present disclosure can be employed to selectively supply current from the first power source 310 to each charging unit 301, thereby preventing excess reaction products from occurring downstream of the negative electrode slurry path 400 and the electrolyte path. This allows a uniform battery reaction to occur in each charging unit 301, preventing a decrease in charging efficiency.

[0072] Fifth Embodiment 8 is a schematic diagram showing a configuration for supplying current to the charging unit 13 (charging unit module 300) in the system of the fifth embodiment. In this embodiment, the secondary battery used in the system is not limited to the flow-type metal-air battery 1, and other general secondary batteries can also be used.

[0073] The configuration shown in Fig. 8 is obtained by adding a second power source 350 and a second current path 360 to the configuration shown in Fig. 4. Note that the second power source 350 may also be connected externally to the present system, and it is not essential that the present system include the second power source 350. In this embodiment, the second current path 360 connects multiple charging units 301 in series, similar to the first current path 320 in Fig. 4. The second current path 360 causes the second power source 350 to supply current to the multiple charging section modules 300 as a whole.

[0074] In the current supply control of this embodiment, the second power source 350 supplies a base current to the entire charging section module 300, and the first power source 310 selectively supplies current (supplies a peak current) to the charging unit 301. In such current supply control, the current level required for each charging unit 301 is shared and supplied by the first power source 310 and the second power source 350, so the output power value of each power source is further reduced compared to when only the first power source 310 supplies current, thereby further reducing the cost of installing the power sources. Furthermore, the reduced output power value of each power source can further reduce ohmic loss, preventing a decrease in charging efficiency.

[0075] FIG. 9 is a schematic diagram showing another configuration for supplying current to the charging section 13 (charging section module 300) in the system of the fifth embodiment.

[0076] The configuration shown in Fig. 9 is obtained by adding a second power source 350 and a second current path 360 to the configuration shown in Fig. 5. In this embodiment, the second current path 360 connects multiple charging units 301 in parallel, similar to the first current path 320 in Fig. 5. The second current path 360 causes the second power source 350 to supply current to the multiple charging portion modules 300 as a whole.

[0077] In this way, even in a configuration in which multiple charging units 301 are connected in parallel to the first power source 310 and the second power source 350, the second power source 350 can supply a base current to the entire charging module 300, and the first power source 310 can supply a peak current to the charging unit 301, thereby achieving the same effect as in the configuration shown in Figure 8.

[0078] 8 and 9 are employed in the flow-type metal-air battery 1, the growth of the metal deposit is promoted for the charging unit 301 to which a peak current is supplied from the first power source 310, and the drag force that the anode liquid exerts on the metal deposit is increased, allowing the metal deposit to be peeled off and discharged. On the other hand, the growth of the metal deposit due to the base current can be obtained for the charging unit 301 to which a peak current is not supplied from the first power source 310. This makes it possible to effectively perform a cycle of growth and peeling of the metal deposit using the drag force of the anode liquid.

[0079] The embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present disclosure should not be interpreted solely by the above-described embodiments, but should be determined based on the claims. [Explanation of symbols]

[0080] 1 Flow-type metal-air battery 11 Storage 13 Live parts 300 live part module 301 Charging Unit 302 charging cell 310 1st power supply 320 First current path 330 Switching Device 331~334 Switch 340 Control Circuit 350 2nd power supply 360 Second current path 400 Anode slurry route

Claims

1. a charging module including a plurality of charging units; a first current path connecting the charging section module to a first power source; a switching device disposed in the first current path and configured to change a connection destination of the charging unit with respect to the first power source; A secondary battery system characterized in that the first current path selectively supplies current from the first power source to each of the charging units by the switching device switching the connection destination of the charging units.

2. The secondary battery system according to claim 1, The charging module is a charging module for a flow-type metal-air battery.

3. The secondary battery system according to claim 1, The secondary battery system is characterized in that the switching device periodically switches the connection destination of the charging unit.

4. The secondary battery system according to claim 1, The secondary battery system is characterized in that the switching device is capable of connecting any one of the charging units to the first power source.

5. The secondary battery system according to claim 1, The secondary battery system is characterized in that the switching device is capable of changing the number of the charging units that can be connected to the first power source.

6. The secondary battery system according to claim 1, The secondary battery system is characterized in that the switching device is a group of switches installed between the secondary battery system and the charging unit.

7. The secondary battery system according to claim 1, The secondary battery system is characterized in that the first current path connects a plurality of the charging units in series.

8. The secondary battery system according to claim 1, The secondary battery system is characterized in that the first current path connects a plurality of the charging units in parallel.

9. The secondary battery system according to claim 2, a secondary battery system characterized in that the charging units are connected to each other by an anode slurry path and an electrolyte path, the anode slurry flows through the anode slurry path, and the electrolyte flows through the electrolyte path.

10. The secondary battery system according to claim 9, The secondary battery system is characterized in that the negative electrode slurry path and the electrolyte path of the plurality of charging units are connected in series.

11. 10. The secondary battery system according to claim 1, 2 or 9, Further, a second current path is provided to connect the charging section module to a second power source, The second current path supplies current from the second power source to the plurality of charging units as a whole.

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