WO2022064883A1 - レドックスフロー電池 - Google Patents

レドックスフロー電池 Download PDF

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Publication number
WO2022064883A1
WO2022064883A1 PCT/JP2021/029448 JP2021029448W WO2022064883A1 WO 2022064883 A1 WO2022064883 A1 WO 2022064883A1 JP 2021029448 W JP2021029448 W JP 2021029448W WO 2022064883 A1 WO2022064883 A1 WO 2022064883A1
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Prior art keywords
positive electrode
electrolytic solution
negative electrode
active material
electrolyte
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PCT/JP2021/029448
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English (en)
French (fr)
Japanese (ja)
Inventor
宏一 加來
遼多 巽
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Sumitomo Electric Industries Ltd
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Sumitomo Electric Industries Ltd
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Application filed by Sumitomo Electric Industries Ltd filed Critical Sumitomo Electric Industries Ltd
Priority to JP2022551187A priority Critical patent/JP7754098B2/ja
Priority to EP21872015.9A priority patent/EP4220783A4/en
Priority to CN202180061721.1A priority patent/CN116075956B/zh
Priority to AU2021350810A priority patent/AU2021350810A1/en
Priority to US18/022,825 priority patent/US12580209B2/en
Publication of WO2022064883A1 publication Critical patent/WO2022064883A1/ja
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04186—Arrangements for control of reactant parameters, e.g. pressure or concentration of liquid-charged or electrolyte-charged reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04201—Reactant storage and supply, e.g. means for feeding, pipes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/18—Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
    • H01M8/184—Regeneration by electrochemical means
    • H01M8/188—Regeneration by electrochemical means by recharging of redox couples containing fluids; Redox flow type batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02B90/10—Applications of fuel cells in buildings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present disclosure relates to redox flow batteries.
  • This application claims priority based on Japanese Patent Application No. 2020-159077 of the Japanese application dated September 23, 2020, and incorporates all the contents described in the Japanese application.
  • Patent Document 1 describes, as a method of operating a redox flow battery, when the valence balance between the positive electrode electrolyte and the negative electrode electrolyte deviates from 3.5, the electrolyte of one tank is moved to the other tank via a pipe. Disclose that you want to.
  • Patent Document 2 discloses a method for determining the distribution of an electrolyte in a flow battery.
  • a positive electrode electrolytic solution and a negative electrode electrolytic solution having an active material are supplied to the flow battery.
  • the method described in Patent Document 2 includes the following configuration.
  • the average oxidation state of the active material in the negative electrode electrolyte and the positive electrode electrolyte is determined.
  • the molar ratio of the active material between the negative electrode electrolyte and the positive electrode electrolyte is adjusted according to the determined average oxidation state.
  • the redox flow battery of the present disclosure has a positive electrode electrolytic solution containing a positive electrode active material and a negative electrode electrolytic solution containing a negative electrode active material.
  • the amount of the positive electrode electrolyte and the amount of the negative electrode electrolyte are different.
  • the liquid amount ratio of the electrolytic solution having a large amount of liquid to the electrolytic solution having a small amount of liquid is 1.05 or more and 5.0 or less.
  • the charged state of the mixed electrolytic solution obtained by mixing the positive electrode electrolytic solution and the negative electrode electrolytic solution at the same ratio as the liquid amount ratio is 2% or more.
  • FIG. 1 is a schematic configuration diagram showing a configuration of a redox flow battery according to an embodiment.
  • FIG. 2 is a schematic configuration diagram showing an example of a cell stack.
  • Patent Document 1 when the valence balance exceeds 3.5, the negative electrode electrolyte is moved to the positive electrode tank, and when the valence balance is less than 3.5, the positive electrode electrolyte is used as the negative electrode. It is stated that it will be moved to the tank.
  • One of the purposes of this disclosure is to provide a redox flow battery having a high energy density.
  • the redox flow battery of the present disclosure has a high energy density.
  • the positive electrode tank for storing the positive electrode electrolyte and the negative electrode tank for storing the negative electrode electrolyte have the same design for cost reduction and simplification of the entire system.
  • the volume of the positive electrode tank and the volume of the negative electrode tank are substantially equal.
  • the amount of the positive electrode electrolytic solution and the amount of the negative electrode electrolytic solution are adjusted to be equal to each other because of the ease of adjusting the liquid level of each electrolytic solution in the positive electrode tank and the negative electrode tank.
  • the positive electrode electrolytic solution and the negative electrode electrolytic solution in the initial state have a state of charge (SOC: State Of Charge) of the mixed electrolytic solution mixed at the same ratio as the ratio of the liquid amount of the positive electrode electrolytic solution and the liquid amount of the negative electrode electrolytic solution.
  • SOC State Of Charge
  • the concentration of each active material contained in the positive electrode electrolytic solution and the negative electrode electrolytic solution is increased, or to increase the utilization rate of the electrolytic solution, that is, the utilization rate of the active material. ..
  • the utilization rate corresponds to the discharge capacity that can actually be used.
  • the utilization rate corresponds to the difference between the charging electricity amount in the upper limit SOC and the charging electricity amount in the lower limit SOC. In other words, the utilization rate indicates the ratio of the active material used for charging / discharging to the concentration of the active material.
  • the concentration of the active substance contained in the electrolytic solution is limited to the solubility of the electrolytic solution in the solvent.
  • the upper limit SOC is increased, the internal resistance increases and the efficiency of the redox reaction decreases. Further, in the range where the SOC is high, side reactions such as electrolysis of water contained in the electrolytic solution are likely to occur. For example, oxygen may be generated at the positive electrode and hydrogen may be generated at the negative electrode. Further, if the upper limit SOC is increased, the active material may precipitate depending on the type and concentration of the active material. Precipitates of active substances cannot be used for charging / discharging, or are difficult to use for charging / discharging due to their small surface area. For this reason, if the active material precipitates in the electrolytic solution, it may not function as the active material. Therefore, the precipitation of the active material may lead to a decrease in the discharge capacity.
  • the range of SOC in which the above-mentioned reduction in the efficiency of the redox reaction, side reactions and precipitation of active materials do not occur. That is, the range of use of SOC is limited in order to suppress deterioration of battery performance and ensure reliability.
  • the optimum SOC range in each electrolytic solution may differ depending on the type of positive electrode active material contained in the positive electrode electrolytic solution and the type of negative electrode active material contained in the negative electrode electrolytic solution.
  • the amount of the positive electrode electrolytic solution and the amount of the negative electrode electrolytic solution are equal, and the SOC of the mixed electrolytic solution is substantially zero. Therefore, it is not possible to independently set the SOC utilization range of the positive electrode electrolyte and the SOC utilization range of the negative electrode electrolyte. In other words, since the positive electrode electrolyte and the negative electrode electrolyte are used in the same SOC usage range, they cannot be used in the optimum SOC range for each electrolyte.
  • the actual SOC usage range of the other electrolytic solution becomes smaller than the optimum SOC range, or It can be excessive. If the actual SOC utilization range is less than the optimum SOC utilization range, the utilization rate of the electrolytic solution, that is, the discharge capacity will decrease, and thus the improvement of the energy density cannot be achieved. On the other hand, if the actual SOC utilization range is larger than the optimum SOC range, the above-mentioned efficiency of the redox reaction is lowered, side reactions and precipitation of active substances occur.
  • the present inventors make the amount of the positive electrode electrolytic solution different from the amount of the negative electrode electrolytic solution, and at the same time, make the SOC of the mixed electrolytic solution different. It is suggested to adjust so that is greater than or equal to a predetermined non-zero value.
  • the redox flow battery according to the embodiment of the present disclosure is It has a positive electrode electrolytic solution containing a positive electrode active material and a negative electrode electrolytic solution containing a negative electrode active material.
  • the amount of the positive electrode electrolyte and the amount of the negative electrode electrolyte are different.
  • the liquid amount ratio of the electrolytic solution having a large amount of liquid to the electrolytic solution having a small amount of liquid is 1.05 or more and 5.0 or less.
  • the charged state of the mixed electrolytic solution obtained by mixing the positive electrode electrolytic solution and the negative electrode electrolytic solution at the same ratio as the liquid amount ratio is 2% or more.
  • the amount of the positive electrode electrolyte and the amount of the negative electrode electrolyte are different, and the SOC of the mixed electrolyte is not zero and is equal to or higher than a predetermined value.
  • the range of use can be optimized. Therefore, the redox flow battery of the present disclosure can improve the energy density. Therefore, the discharge capacity in the initial state can be increased.
  • the amounts of the positive electrode electrolyte and the negative electrode electrolyte are positively different, and the SOC of the mixed electrolyte is set to a predetermined value other than zero.
  • the range of use of SOC in each electrolytic solution can be expanded as compared with the conventional case.
  • the charged state of the mixed electrolytic solution is 20% or less.
  • the above form can sufficiently increase the energy density.
  • a positive electrode tank for storing the positive electrode electrolyte and a negative electrode tank for storing the negative electrode electrolyte are provided.
  • the ratio of the volume of the tank that stores the electrolytic solution having a large amount of liquid to the volume of the tank that stores the electrolytic solution having a small amount of liquid is 1.0 or more and 6.0 or less. Can be mentioned.
  • the volume of the positive electrode tank and the volume of the negative electrode tank may be the same or different.
  • the volumes of both tanks are the same, that is, the volume ratio between the positive electrode tank and the negative electrode tank is 1.0, the cost of the tanks can be reduced and the design can be simplified.
  • the volumes of both tanks are different, it is easy to store the electrolytic solutions having different liquid volumes in each tank. Further, when the volume ratio between the positive electrode tank and the negative electrode tank is different from the liquid volume ratio between the positive electrode electrolytic solution and the negative electrode electrolytic solution, the degree of freedom in design including the tank and the piping is high.
  • the positive electrode active material and the negative electrode active material may be metal ions made of the same element.
  • the metal ion may contain vanadium ion.
  • the positive electrode active material and the negative electrode active material are metal ions composed of different elements.
  • the positive electrode active material is at least one metal ion selected from the group consisting of iron ions, vanadium ions, and manganese ions.
  • the negative electrode active material may be at least one metal ion selected from the group consisting of zinc ion, chromium ion, vanadium ion, and titanium ion.
  • the above form can construct a redox flow battery with high energy density.
  • the positive electrode active material may contain manganese ions, and the negative electrode active material may contain titanium ions.
  • the positive electrode electrolytic solution and the negative electrode electrolytic solution may contain both manganese ions and titanium ions.
  • the redox flow battery according to the embodiment of the present disclosure is It has a positive electrode electrolytic solution containing a positive electrode active material and a negative electrode electrolytic solution containing a negative electrode active material.
  • the amount of the positive electrode electrolyte and the amount of the negative electrode electrolyte are different.
  • the liquid amount ratio of the electrolytic solution having a large amount of liquid to the electrolytic solution having a small amount of liquid is 1.05 or more and 5.0 or less.
  • the charged state of the mixed electrolytic solution obtained by mixing the positive electrode electrolytic solution and the negative electrode electrolytic solution at the same ratio as the liquid amount ratio is 2% or more and 20% or less.
  • the positive electrode active material is at least one metal ion selected from the group consisting of iron ions, vanadium ions, and manganese ions.
  • the negative electrode active material is at least one metal ion selected from the group consisting of zinc ion, chromium ion, vanadium ion, and titanium ion.
  • the redox flow battery described above includes the configurations of the redox flow battery described in (1), (2), and (7) described above, the energy density can be increased.
  • the RF battery 1 is charged and discharged using a positive electrode electrolytic solution 2 containing a positive electrode active material and a negative electrode electrolytic solution 3 containing a negative electrode active material.
  • the positive electrode active material and the negative electrode active material are typically metal ions whose valence changes due to redox.
  • the RF battery 1 is typically connected to the power system 90 via an AC / DC converter 80 or a substation facility 81.
  • the RF battery 1 can charge the electric power generated by the power generation unit 91 and discharge the charged electric power to the load 92.
  • the power generation unit 91 is a power generation facility using natural energy such as solar power generation and wind power generation, and other general power plants.
  • the RF battery 1 is used, for example, for load leveling, instantaneous low compensation, emergency power supply, and output smoothing of renewable energy power generation.
  • the RF battery 1 circulates a battery cell 10 for charging and discharging, a positive electrode tank 12 for storing a positive electrode electrolytic solution 2, a negative electrode tank 13 for storing a negative electrode electrolytic solution 3, and a positive electrode electrolytic solution 2 and a negative electrode electrolytic solution 3, respectively. It is provided with a circulation flow path to be allowed to flow.
  • the circulation flow path circulates the negative electrode electrolyte 3 between the negative electrode tank 13 and the battery cell 10 and the circulation flow path for the positive electrode electrolyte 2 that circulates the positive electrode electrolyte 2 between the positive electrode tank 12 and the battery cell 10. It is provided with a circulation flow path for the negative electrode electrolyte solution.
  • the battery cell 10 has a positive electrode 104, a negative electrode 105, and a diaphragm 101 interposed between the positive electrode 104 and the negative electrode 105.
  • the battery cell 10 is separated into a positive electrode cell 102 and a negative electrode cell 103 by a diaphragm 101.
  • the diaphragm 101 is, for example, an ion exchange membrane that allows hydrogen ions to permeate.
  • the positive electrode cell 102 has a built-in positive electrode 104.
  • the negative electrode cell 103 has a built-in negative electrode 105.
  • the positive electrode electrolyte 2 is supplied to the positive electrode cell 102.
  • the negative electrode electrolytic solution 3 is supplied to the negative electrode cell 103.
  • the outbound pipe 108 and the inbound pipe 110 connecting the battery cell 10 and the positive electrode tank 12 are provided, and the outbound pipe 109 and the inbound pipe 111 connecting the battery cell 10 and the negative electrode tank 13 are provided.
  • Pumps 112 and 113 are provided in the outbound pipes 108 and 109, respectively.
  • the positive electrode electrolyte 2 is supplied from the positive electrode tank 12 to the positive electrode cell 102 through the outbound pipe 108 by the pump 112.
  • the positive electrode electrolytic solution 2 discharged from the positive electrode cell 102 through the positive electrode cell 102 is returned to the positive electrode tank 12 through the return pipe 110.
  • the negative electrode electrolytic solution 3 is supplied from the negative electrode tank 13 to the negative electrode cell 103 through the outward pipe 109 by the pump 113.
  • the negative electrode electrolytic solution 3 discharged from the negative electrode cell 103 through the negative electrode cell 103 is returned to the negative electrode tank 13 through the return pipe 111. That is, the circulation flow path is composed of the outward pipes 108 and 109 and the return pipes 110 and 111.
  • the RF battery 1 usually uses a form called a cell stack 100 in which a plurality of battery cells 10 are stacked, as shown in FIG.
  • the cell stack 100 is configured by sandwiching the sub-stack 20 from both sides of the sub-stack 20 between two end plates 22 and tightening the end plates 22 on both sides by a tightening mechanism 23.
  • FIG. 2 shows a cell stack 100 with a plurality of substacks 20.
  • the sub-stack 20 has a structure in which the cell frame 30, the positive electrode 104, the diaphragm 101, and the negative electrode 105 are repeatedly laminated in this order, and the supply / discharge plates 21 are arranged at both ends of the laminated body.
  • the outbound pipes 108 and 109 and the inbound pipes 110 and 111 shown in FIG. 1 constituting the above-mentioned circulation flow path are connected to the supply / discharge plate 21.
  • the number of stacked battery cells 10 in the cell stack 100 can be appropriately selected.
  • the cell frame 30 has a bipolar plate 31 and a frame body 32.
  • the bipolar plate 31 is arranged between the positive electrode 104 and the negative electrode 105.
  • the frame body 32 is provided around the bipolar plate 31.
  • the positive electrode 104 is arranged on one side of the bipolar plate 31 so as to face each other.
  • the negative electrode 105 is arranged on the other surface side of the bipolar plate 31 so as to face each other.
  • One battery cell 10 is formed by arranging the positive electrode 104 and the negative electrode 105 with the diaphragm 101 sandwiched between the bipolar plates 31 of the adjacent cell frames 30.
  • the frame body 32 of the cell frame 30 is formed with liquid supply manifolds 33, 34 and drainage manifolds 35, 36, and liquid supply slits 33s, 34s and drainage slits 35s, 36s.
  • the positive electrode electrolytic solution is supplied from the liquid supply manifold 33 to the positive electrode electrode 104 via the liquid supply slit 33s.
  • the positive electrode electrolytic solution supplied to the positive electrode 104 is discharged to the drainage manifold 35 via the drainage slit 35s.
  • the negative electrode electrolytic solution is supplied from the liquid supply manifold 34 to the negative electrode electrode 105 via the liquid supply slit 34s.
  • the negative electrode electrolytic solution supplied to the negative electrode electrode 105 is discharged to the drainage manifold 36 via the drainage slit 36s.
  • the liquid supply manifolds 33 and 34 and the drainage manifolds 35 and 36 are provided so as to penetrate the frame body 32, and the cell frames 30 are laminated to form a flow path for each electrolytic solution.
  • Each of these flow paths communicates with the outward pipes 108 and 109 and the return pipes 110 and 111 shown in FIG. 1 via the supply / discharge plate 21, respectively.
  • the positive electrode electrolytic solution and the negative electrode electrolytic solution can be circulated in the battery cell 10 by each of the above flow paths.
  • One of the features of the RF battery 1 of the embodiment is that the liquid amount of the positive electrode electrolytic solution 2 and the liquid amount of the negative electrode electrolytic solution 3 are different, and the liquid amount of the positive electrode electrolytic solution 2 and the liquid amount of the negative electrode electrolytic solution 3 are different.
  • the SOC of the mixed electrolytic solution obtained by mixing the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 at the same ratio as the ratio is not zero and is equal to or higher than a predetermined value.
  • the liquid amount ratio between the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 is 1.05 or more and 5.0 or less.
  • the SOC of the mixed electrolyte is 2% or more.
  • the positive electrode electrolyte 2 contains a positive electrode active material.
  • the positive electrode active material include at least one metal ion selected from the group consisting of iron (Fe) ion, vanadium (V) ion, and manganese (Mn) ion.
  • V ions they mainly exist in the state of divalent or trivalent ions (V 2+ / V 3+ ).
  • Fe ion it mainly exists in the state of divalent or trivalent ion (Fe 2+ / Fe 3+ ).
  • Mn ion it mainly exists in the state of divalent or trivalent ion (Mn 2+ / Mn 3+ ).
  • the negative electrode electrolyte 3 contains a negative electrode active material.
  • the negative electrode active material include at least one metal ion selected from the group consisting of zinc (Zn) ion, chromium (Cr) ion, V ion, and titanium (Ti) ion.
  • Zn zinc
  • Cr chromium
  • V ion titanium
  • Ti titanium
  • V ions they mainly exist in the state of tetravalent or pentavalent ions (V 4+ / V 5+ ).
  • Cr ions they mainly exist in the state of divalent or trivalent ions (Cr 2+ / Cr 3+ ).
  • Ti ions they mainly exist in the state of trivalent or tetravalent ions (Ti 3+ / Ti 4+ ).
  • the tetravalent Ti ion (Ti 4+ ) also includes, for example, the form of TiO 2+ .
  • Zn ion it mainly exists as a divalent ion (Zn 2+ ).
  • Zn ions exist in the state of metallic zinc during charging.
  • the positive electrode active material and the negative electrode active material it is also possible to use non-metal organic active materials in addition to metal ions.
  • the organic active material include quinone compounds such as 2,6-dihydroxyanthraquinone and radicals such as 2,2,6,6-tetramethylpiperidine 1-oxyl.
  • the positive electrode active material and the negative electrode active material may be metal ions made of the same element or metal ions made of different elements.
  • the positive electrode active material and the negative electrode active material are the same type of metal ions, it is typically mentioned that both the positive electrode active material and the negative electrode active material contain V ions.
  • the positive electrode active material and the negative electrode active material are different types of metal ions, it is typically mentioned that the positive electrode active material contains Mn ions and the negative electrode active material contains Ti ions.
  • the positive electrode active material and the negative electrode active material can each be appropriately selected from the above-mentioned metal ions.
  • the specific combination of the positive electrode active material and the negative electrode active material is shown below.
  • Negative electrode active material Ti ion (Ti 3+ / Ti 4+ )
  • the electromotive force is determined by the combination of the positive electrode active material and the negative electrode active material.
  • a form in which both the positive electrode active material and the negative electrode active material are V ions, or a form in which the positive electrode active material is Mn ion and the negative electrode active material is Ti ion can obtain high electromotive force.
  • the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 may contain the same kind of metal ions.
  • the positive electrode active material and the negative electrode active material are metal ions of the same element, and at least one kind of metal ion contained in the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 is of the same type.
  • all the metal ions contained in the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 are of the same type.
  • each metal ion contained in the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 permeates through the diaphragm 101 of the battery cell 10 and becomes the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 by repeating charging and discharging for a long period of time. There may be liquid transfer between the two, or one electrolyte may move through the diaphragm 101 to the other electrolyte. Since the positive electrode electrolyte 2 and the negative electrode electrolyte 3 each contain the same type of metal ions, metal ions move or transfer between the positive electrode electrolyte 2 and the negative electrode electrolyte 3 due to repeated charging and discharging. Even if it does, it is easy to maintain the battery performance.
  • the metal ions can function as active materials in both electrolytic solutions. Further, when the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 contain the same kind of metal ions, even if the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 are mixed, they are contained in the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3, respectively. The type of metal ion does not change. In order to correct the liquid transfer and the like, the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 can be easily mixed.
  • the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 contain both Mn ion and Ti ion.
  • Mn ions function as the positive electrode active material.
  • Ti ions function as a negative electrode active material.
  • Mn ions may precipitate as Mn oxide in the positive electrode electrolytic solution 2. This is because trivalent Mn ions (Mn 3+ ) are unstable, so Mn 3+ is likely to precipitate as Mn oxides such as MnO 2 during charging.
  • the precipitation of Mn ions can be suppressed by the Ti ions.
  • the Ti ion contained in the positive electrode electrolytic solution 2 and the Mn ion contained in the negative electrode electrolytic solution 3 do not function as active materials, respectively.
  • the Mn ions contained in the negative electrode electrolytic solution 3 are mainly for equalizing the metal ion species in both electrolytic solutions.
  • An aqueous solution can be preferably used as the solvent of the positive electrode electrolytic solution 2 and the solvent of the negative electrode electrolytic solution 3.
  • the solvent include sulfuric acid (H 2 SO 4 ) aqueous solution, phosphoric acid (H 3 PO 4 ) aqueous solution, nitric acid (HNO 3 ) and the like.
  • an aqueous sulfuric acid solution is easy to use.
  • the concentration of the positive electrode active material contained in the positive electrode electrolytic solution 2 and the concentration of the negative electrode active material contained in the negative electrode electrolytic solution 3 are, for example, 0.3 M or more and 5 M or less, respectively.
  • the above “M” is a molar concentration (mol / L).
  • the above “L” means liter. 1L is 10 -3 m 3 .
  • the concentration of the active material in the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 is 0.3 M or more, it is easy to increase the energy density. Since the energy density can be increased as the concentration of the active material is higher, the concentration of the active material is preferably 0.5 M or more, more preferably 1.0 M or more.
  • the concentration of the active substance may be 5 M or less, further 2 M or less.
  • the concentration of Ti ions contained in the positive electrode electrolytic solution 2 and the concentration of Mn ions contained in the negative electrode electrolytic solution 3 are, for example, 0. Examples thereof include 3M or more and 5M or less, and further 0.5M or more and 2M or less.
  • the concentration of the positive electrode active material contained in the positive electrode electrolytic solution 2 and the concentration of the negative electrode active material contained in the negative electrode electrolytic solution 3 may be the same or different.
  • the positive electrode active material and the negative electrode active material are the same type of metal ion, it is easy to adjust so that the concentrations of the respective active materials are the same.
  • the solubility differs depending on the type of metal ion, so that the concentration of each active material may be adjusted to be different.
  • the liquid volume ratio between the positive electrode electrolyte 2 and the negative electrode electrolyte 3 is 1.05 or more and 5.0 or less.
  • the liquid volume ratio is the ratio of the liquid volume of the electrolytic solution having a large liquid volume to the electrolytic liquid having a small liquid volume among the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3.
  • the liquid amount of the positive electrode electrolyte 2 refers to the volume of the positive electrode electrolyte 2.
  • the liquid amount of the negative electrode electrolyte 3 refers to the volume of the negative electrode electrolyte 3.
  • the liquid amount ratio may be set based on the concentration of the positive electrode active material, the concentration of the negative electrode active material, and the optimum SOC range of each electrolytic solution.
  • the liquid amount ratio is 1.05 or more, the effect of improving the energy density can be easily obtained.
  • the liquid volume ratio is 5.0 or less, it is possible to prevent the liquid volume of the electrolytic solution having a large liquid volume from becoming too large. As a result, the tank for storing the electrolytic solution having a large amount of liquid does not become too large.
  • the liquid volume ratio include 1.1 or more and 4.0 or less, 1.2 or more and 3.0 or less, and 1.3 or more and 2.5 or less.
  • the volume ratio between the positive electrode tank 12 and the negative electrode tank 13 is 1.0 or more and 6.0 or less.
  • the volume ratio is the ratio of the volume of the tank that stores the electrolytic solution having a large amount of liquid to the volume of the tank that stores the electrolytic solution having a small amount of liquid among the positive electrode tank 12 and the negative electrode tank 13.
  • the volume of the positive electrode tank 12 and the volume of the negative electrode tank 13 may be set according to the amount of the positive electrode electrolytic solution 2 and the amount of the negative electrode electrolytic solution 3, respectively.
  • the volume of the positive electrode tank 12 and the volume of the negative electrode tank 13 may be the same or different.
  • the volume ratio may be set based on the liquid volume ratio described above.
  • the volume of each of the positive electrode tank 12 and the negative electrode tank 13 shall be set to the size corresponding to the respective liquid volumes of the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3. Is easy.
  • the volume ratio may be the same as the liquid volume ratio or may be different from the liquid volume ratio. Even if the liquid volume ratio is 1.05 or more, the volume of the gas phase portion above the liquid level of the positive electrode electrolyte 2 in the positive electrode tank 12 and the air above the liquid level of the negative electrode electrolyte 3 in the negative electrode tank 13. Considering the volume of the phase portion, it is not always necessary to set the volume ratio to 1.05 or more according to the liquid volume ratio. When the liquid volume ratio is sufficiently small, the volume ratio may be 1.0 in order to simplify the manufacturing cost and design of the tank. That is, it is allowed that the volume of the positive electrode tank 12 and the volume of the negative electrode tank 13 are the same.
  • the case where the liquid amount ratio is sufficiently small means, for example, the case where the liquid amount ratio is less than 1.5.
  • the gas phase portion in each tank may have a certain margin for design reasons such as arranging the end portions of the outbound pipes 108, 109 and the inbound pipes 110, 111. .. Therefore, even if the liquid volume ratio is 5.0, it may be desirable to design the volume ratio to be about 6.0.
  • the volume ratio is, for example, 1.05 or more and 5.0 or less, 1.1 or more and 4.0 or less, 1.2 or more and 3.0 or less, and 1.3 or more and 2.5 or less according to the liquid volume ratio. Can be mentioned.
  • the volume ratio can be set according to the volume of the gas phase portion in the positive electrode tank 12, the volume of the gas phase portion in the negative electrode tank 13, and other design conditions.
  • the volume of the positive electrode tank 12 and the volume of the negative electrode tank 13 may be different.
  • an object having an appropriate volume may be submerged in at least one of the tanks.
  • the positive electrode electrolyte 2 is stored not only in the positive electrode tank 12 but also in each pipe.
  • the negative electrode electrolyte 3 is stored not only in the negative electrode tank 13 but also in each pipe. Therefore, the amount of the positive electrode electrolytic solution 2 that can be stored is determined by the total of the volume of the positive electrode tank 12 and the volume of the pipe.
  • the amount of the negative electrode electrolytic solution 3 that can be stored is determined by the total of the volume of the negative electrode tank 13 and the volume of the pipe. Therefore, not only by adjusting the volume ratio of the positive electrode tank 12 and the negative electrode tank 13 to the liquid volume ratio, but also by adjusting the volume of each pipe, the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 having a predetermined liquid volume ratio can be obtained. Can be stored.
  • the volume ratio can be variously selected regardless of the liquid volume ratio by changing the length of each pipe or submerging the object in at least one of the tanks.
  • the SOC of the mixed electrolytic solution obtained by mixing the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 at the same ratio as the above liquid volume ratio is 2% or more.
  • the SOC of the mixed electrolytic solution may be set based on the concentration of the positive electrode active material, the concentration of the negative electrode active material, the optimum SOC range of each electrolytic solution, and the liquid volume ratio described above. When the SOC of the mixed electrolyte is 2% or more, the effect of improving the energy density is enhanced.
  • the SOC of the mixed electrolyte may be appropriately set, but the practical range is 20% or less.
  • the SOC of the mixed electrolytic solution may be, for example, 2% or more and 20% or less, and further 3% or more and 10% or less.
  • the SOC of the mixed electrolytic solution is defined as follows according to the state in which the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 are mixed at the same ratio as the liquid amount ratio.
  • the concentration of the reduced substance is Cpr
  • the concentration of the oxidized substance is Cpo
  • the total concentration is Cp.
  • the concentration of the reduced substance is Cnr
  • the concentration of the oxidized substance is Cno
  • the total concentration is Cn.
  • the ratio of the concentration of the oxidant to the concentration of the reduced substance is defined by the SOC of the RF battery for each of the positive electrode active material and the negative electrode active material.
  • the positive electrode electrolytic solution and the negative electrode electrolytic solution are mixed at a specific SOC.
  • the liquid amount vp (L) of the positive electrode electrolytic solution and the liquid amount vn (L) of the negative electrode electrolytic solution are different, that is, when vp ⁇ vn, the liquid amount ratio between the positive electrode electrolytic solution and the negative electrode electrolytic solution is the same.
  • the mixed electrolytic solution is a mixture of the positive electrode electrolytic solution and the negative electrode electrolytic solution at bp: vn.
  • the amount of electricity oxidized or reduced in the above corresponds to (Cpo ⁇ vp-Cnr ⁇ vn) / (bp + vn) ⁇ F [C].
  • m (Cpo ⁇ vp-Cnr ⁇ vn) / (vp + vn) [mol / L]
  • m in this formula corresponds to the concentration of the active substance responsible for the amount of oxidized or reduced electricity.
  • the SOC of the mixed electrolyte is defined as (m / Cp) ⁇ 100 [%].
  • m ⁇ 0 the SOC of the mixed electrolyte is defined as (m / Cn) ⁇ 100 [%].
  • the positive electrode active material causes a reaction of two or more electrons and a reaction of one electron or more and a reaction of two or more electrons coexist. It is assumed that the positive electrode active material occurs up to the Np electron reaction and the negative electrode active material occurs up to the Nn electron reaction.
  • the symbols Np and Nn are natural numbers of 2 or more, respectively.
  • the total concentration Cp of the positive electrode active material and the total concentration Cn of the negative electrode active material are expressed as follows.
  • Example 1 In Example 1, a case where an electrolytic solution containing 1 mol / L Ti ion and 1 mol / L Mn ion is used as a positive electrode electrolytic solution and a negative electrode electrolytic solution will be described as an example.
  • Mn 2+ which is a reducing body
  • Mn 3+ which is an oxidizing body
  • Ti 4+ which is an oxidizing body
  • Ti which is a reducing body
  • negative electrode active materials There are 3+ and.
  • the mixed electrolytic solution when the positive electrode electrolytic solution and the negative electrode electrolytic solution are mixed according to the ratio between the liquid amount of the positive electrode electrolytic solution and the liquid amount of the negative electrode electrolytic solution corresponds to 0.02 mol / L as Mn 3+ . Only charged.
  • Example 2 In Example 2, in the RF battery using the same electrolytic solution as in Example 1, it is assumed that MnO 2 , which is an oxidant that reacts with two electrons, is also present in the positive electrode electrolytic solution as the positive electrode active material.
  • Cpo 1 corresponds to the concentration of Mn 3+ .
  • Cpo 2 corresponds to the concentration of MnO 2 .
  • Example 3 In Example 3, a case where an electrolytic solution containing only 1 mol / L V ions as an active material is used for the positive electrode electrolytic solution and the negative electrode electrolytic solution will be described as an example.
  • V 3+ which is a reducing body
  • V 4+ which is an oxidizing body
  • V 4+ which is an oxidizing body
  • V which is a reducing body
  • V 4+ may be treated as a reducing body and V 5+ as an oxidant as a positive electrode active material
  • V 3+ may be treated as an oxidant and V 2+ as a reducing body as a negative electrode active material.
  • the SOC in the initial state of the RF battery should be assumed here. Therefore, as in the former case, it is appropriate to consider that V 3+ of the reducing body and V 4+ of the oxidizing body exist as the positive electrode active material, and V 4+ of the oxidizing body and V 3+ of the reducing body exist as the negative electrode active material. Is.
  • the SOC of the mixed electrolytic solution is 1%.
  • the mixed electrolytic solution at this time contains 0.49M of V 3+ and 0.51M of V 4+ . In this case, it is customarily expressed as "3.51 valence as an average valence".
  • the SOC of the mixed electrolytic solution corresponds to the imbalance between the valence of the positive electrode electrolytic solution 2 and the valence of the negative electrode electrolytic solution 3.
  • the fact that the SOC of the mixed electrolytic solution is above a certain level means that in the state where the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 are mixed, the positive electrode active material in the oxidized state or the negative electrode active material in the reduced state is present in a certain ratio or more. Means to do.
  • the SOC of the mixed electrolytic solution is obtained as the SOC of the entire electrolytic solution when the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 are mixed.
  • the SOC referred to here is expressed on the premise that the positive electrode active material or the negative electrode active material undergoes a one-electron reaction.
  • the positive electrode electrolytic solution 2 contains the positive electrode active material at a concentration of 1 mol / L, it is assumed that the positive electrode active material in an oxidized state exists when the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 are mixed.
  • the SOC of the mixed electrolyte is 2%.
  • the SOC of the mixed electrolyte is 2%
  • 96485 (C / mol) x 0.02 (mol / L) 1929.7 (C / L), where the Faraday constant is 96485 (C / mol).
  • the SOC of the mixed electrolytic solution is 20%.
  • the SOC of the mixed electrolytic solution is 20%
  • the negative electrode electrolytic solution 3 contains the negative electrode active material at a concentration of 1 mol / L
  • the negative electrode active material in a reduced state exists when the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 are mixed.
  • the SOC of the mixed electrolyte is defined as 2%.
  • the SOC of the mixed electrolyte is 2%
  • the SOC of the mixed electrolytic solution is 20%
  • the SOC of the mixed electrolytic solution is 20%
  • the active material is based on the concentration of the active material of either the positive electrode electrolytic solution 2 or the negative electrode electrolytic solution 3. Is oxidized or reduced.
  • the SOC of the mixed electrolytic solution may be adjusted by adjusting the SOC of each electrolytic solution, that is, the valence of the active material in the electrolytic solution when the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 are produced. Further, after the electrolytic solution is prepared, the positive electrode active material of the positive electrode electrolytic solution 2 may be oxidized, or the negative electrode active material of the negative electrode electrolytic solution 3 may be reduced.
  • Examples of the method for oxidizing the positive electrode active material include natural oxidation with air and chemical oxidation with an oxidizing agent.
  • As the oxidizing agent for example, hydrogen peroxide solution can be used.
  • Examples of the method for reducing the negative electrode active material include chemical reduction with a reducing agent.
  • As the reducing agent for example, hydrogen, sulfurous acid, oxalic acid and the like can be used.
  • the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 to a predetermined SOC, oxidizing the positive electrode active material and reducing the negative electrode active material, one electrolytic solution having the SOC adjusted is left, and the other electrolytic solution is used.
  • the liquid amount of the positive electrode electrolytic solution 2 and the liquid amount of the negative electrode electrolytic solution 3 are different and the valences are different, so that the SOC of the positive electrode electrolytic solution 2 can be used.
  • the range of use of SOC of the negative electrode electrolyte 3 can be optimized.
  • the usage range of SOC is the range of SOC actually used when charging / discharging. The reason why the usage range of SOC can be optimized will be described below.
  • the optimum SOC range for each of the positive electrode electrolyte and the negative electrode electrolyte is mainly determined by the type of each metal ion serving as the positive electrode active material and the negative electrode active material.
  • the optimum SOC range for each electrolyte may also vary depending on the concentration of the active material and the concentration of the solvent. Assuming that there is no influence due to the movement of metal ions or liquid transfer between the two electrolytes, the optimum SOC range of each electrolyte does not change depending on the combination of the positive electrode active material and the negative electrode active material.
  • the upper limit of the optimum SOC range for each electrolytic solution is to set the SOC value at which problems such as an increase in internal resistance, side reactions and precipitation of active material do not occur at the end of charging.
  • the lower limit of the optimum SOC range of each electrolytic solution is set to the SOC value at which problems such as an increase in internal resistance and precipitation of active material do not occur at the end of discharge.
  • the optimum SOC range of the positive electrode electrolyte is 1/2 of the optimum SOC range of the negative electrode electrolyte.
  • the actual use range of the SOC in the negative electrode electrolyte is limited by the SOC range of the positive electrode electrolyte.
  • the actual SOC utilization range of the negative electrode electrolyte is limited to 1/2 of the optimum SOC range at the maximum. Therefore, the range of use of SOC in the negative electrode electrolyte is reduced. Since the range of use of the SOC of the negative electrode electrolyte is limited by the positive electrode electrolyte, improvement in energy density cannot be achieved.
  • the actual SOC usage range of the positive electrode electrolyte is 2 compared to the optimum SOC range. It will be doubled. That is, in the positive electrode electrolyte, at least one of the SOC at the end of charging and the SOC at the end of discharging is out of the optimum SOC range. If the SOC at the end of charging in the positive electrode electrolyte is higher than the optimum SOC range, side reactions may occur or the positive electrode active material may precipitate. The precipitate of the positive electrode active material cannot be used for charging / discharging or is difficult to use for charging / discharging. When the SOC at the end of discharge of the positive electrode electrolyte is lower than the optimum SOC range, the internal resistance increases and the reaction efficiency decreases.
  • the optimum SOC range of the positive electrode electrolyte is 1/2 of the optimum SOC range of the negative electrode electrolyte
  • the positive electrode electrolyte and the negative electrode electrolyte can be used in each of the positive electrode electrolytes and the negative electrode electrolyte. It is possible to charge and discharge the amount of electricity corresponding to the optimum SOC range. Therefore, the energy density can be increased.
  • the actual SOC utilization range is the optimum SOC range for both the positive electrode electrolyte and the negative electrode electrolyte by adjusting only the liquid volume ratio.
  • the range of use of SOC in the positive electrode electrolyte or the negative electrode electrolyte may deviate from the optimum SOC range. Therefore, in one or both of the positive electrode electrolyte and the negative electrode electrolyte, a side reaction or precipitation of an active material may occur in a region where the SOC utilization range is higher than the optimum SOC range. On the other hand, in a region where the SOC utilization range is lower than the optimum SOC range, the internal resistance increases and the reaction efficiency decreases.
  • the usage range of SOC in each electrolytic solution can be adjusted to the optimum SOC range. It becomes possible to do. For example, when the SOC at the end of discharge in the positive electrode electrolytic solution is lower than the optimum SOC range, a part of the positive electrode active material in the positive electrode electrolytic solution is pre-oxidized, and the positive electrode electrolytic solution and the negative electrode electrolytic solution are separated. In the mixed state, the valence is adjusted so that the positive electrode active material in the oxidized state is present.
  • the SOC at the end of discharge in the positive electrode electrolyte can be brought closer to the optimum SOC range. Therefore, it is possible to solve the problem that the reaction efficiency is lowered.
  • the SOC at the end of charging in the positive electrode electrolytic solution is higher than the optimum SOC range, a part of the negative electrode active material in the negative electrode electrolytic solution is reduced in advance, and the positive electrode electrolytic solution and the negative electrode electrolytic solution are separated. In the mixed state, the valence is adjusted so that the negative electrode active material in the reduced state is present.
  • the SOC at the end of charging in the positive electrode electrolyte can be brought closer to the optimum SOC range. Therefore, by adjusting the liquid volume ratio between the positive electrode electrolyte and the negative electrode electrolyte and the SOC of the mixed electrolyte, the effect of improving the energy density can be further enhanced.
  • the case where the optimum SOC range of the positive electrode electrolyte is smaller than the optimum SOC range of the negative electrode electrolyte has been described as an example.
  • the same can be considered when the optimum SOC range of the negative electrode electrolyte is smaller than the optimum SOC range of the positive electrode electrolyte.
  • the liquid amount of the positive electrode electrolyte 2 and the liquid amount of the negative electrode electrolyte 3 are different and the valences are different, so that the SOC of the positive electrode electrolyte 2 is different.
  • Both the range of use and the range of use of the SOC of the negative electrode electrolyte 3 can be optimized. Therefore, it is possible to improve the energy density, and it is possible to obtain an RF battery having a high energy density.
  • the liquid volume ratio between the positive electrode electrolyte 2 and the negative electrode electrolyte 3 is 1.05 or more and 5.0 or less, and the SOC of the mixed electrolyte is 2% or more, which has the effect of improving the energy density. It will be higher.
  • the initial state includes, for example, a state before starting the operation of the RF battery 1.
  • the optimum SOC range of the positive electrode electrolyte 2 and the optimum SOC range of the negative electrode electrolyte 3 may differ.
  • the liquid amount of the positive electrode electrolytic solution 2 and the liquid amount of the negative electrode electrolytic solution 3 are equal, and the valence of the positive electrode electrolytic solution 2 and the valence of the negative electrode electrolytic solution 3 are different from each other.
  • the usage range of the SOC of the positive electrode electrolyte 2 and the usage range of the SOC of the negative electrode electrolyte 3 are both limited to the overlapping range of the respective optimum SOC ranges.
  • the positive electrode electrolytic solution 2 and the negative electrode electrolytic solution 3 cannot be used within the respective optimum SOC ranges.
  • the SOC usage range is set according to the optimum SOC range of one electrolytic solution, the SOC usage range of the other electrolytic solution may be smaller or larger than the optimum SOC range.
  • the SOC utilization range of the positive electrode electrolyte 2 and the SOC utilization range of the negative electrode electrolyte 3 can be controlled. Can be approached or matched to the optimum SOC range of.
  • the positive electrode active material and the negative electrode active material are metal ions composed of different elements, there is a high possibility that the optimum SOC utilization range of the positive electrode electrolyte 2 and the optimum SOC utilization range of the negative electrode electrolyte 3 are different. Further, the solubility of metal ions in the positive electrode electrolyte 2 and the solubility of metal ions in the negative electrode electrolyte 3 differ depending on the type of metal ions. Due to the difference in solubility, the concentration of the active material contained in the positive electrode electrolytic solution 2 and the concentration of the active material contained in the negative electrode electrolytic solution 3 are adjusted to be different.
  • the positive electrode active material and the negative electrode active material are different types of metal ions, it can be obtained by optimizing both the SOC utilization range of the positive electrode electrolyte 2 and the SOC utilization range of the negative electrode electrolyte 3. It is considered that the merit is great.
  • the concentration of the positive electrode active material is 1.0 mol / L, and the concentration of the negative electrode active material is 1.0 mol / L. Further, the lower limit of the optimum SOC range of the positive electrode electrolyte is 20%, and the upper limit is 80%. The lower limit of the optimum SOC range of the negative electrode electrolyte is 17%, and the upper limit is 80%. That is, the usage range of the SOC of the positive electrode electrolyte is limited to 20% or more and 80% or less, and the usage range of the SOC of the negative electrode electrolyte is limited to 17% or more and 80% or less. The SOC is calculated on the assumption that each active substance undergoes a one-electron reaction. The discharge capacity under this condition was calculated. The discharge capacity was calculated for each of the following cases. Table 1 shows the discharge capacity in each case.
  • the liquid amount ratio is 1.05
  • the liquid amount of the positive electrode electrolytic solution is 1.05 times the liquid amount of the negative electrode electrolytic solution.
  • the SOC of the mixed electrolytic solution the amount of electricity charged when the positive electrode electrolytic solution and the negative electrode electrolytic solution are mixed at the same ratio as the liquid amount ratio is represented by the SOC of the positive electrode electrolytic solution.
  • the positive electrode electrolytic solution and the negative electrode electrolytic solution are mixed at a ratio of 1: 1.
  • the positive electrode electrolytic solution and the negative electrode electrolytic solution are mixed at a ratio of 1.05: 1.
  • the positive electrode SOC range is the range in which the SOC of the positive electrode electrolytic solution is used during charging and discharging.
  • the positive electrode SOC range is determined as follows. Here, the valence shift to the positive electrode electrolyte side is considered.
  • the concentration of the positive electrode active material contained in the positive electrode electrolytic solution is A (mol / L), and the SOC of the mixed electrolytic solution is x (%).
  • the concentration of the negative electrode active material contained in the negative electrode electrolytic solution is B (mol / L), and the optimum SOC range of the negative electrode electrolytic solution is b1 (%) to b2 (%).
  • the SOC (%) at the end of discharge shall be the larger value of [ ⁇ X + (B ⁇ b1 + X) / r ⁇ / A] and [a1].
  • the SOC (%) at the end of charging is the smaller value of [ ⁇ X + (B ⁇ b2 + X) / r ⁇ / A] and [a2].
  • the positive electrode SOC range is a value obtained by [SOC at the end of charge-SOC at the end of discharge].
  • the discharge capacity can be increased in the case (d) in which the liquid volume ratio between the positive electrode electrolyte and the negative electrode electrolyte is 1.05 and the SOC of the mixed electrolyte is 2%. .. That is, the energy density can be improved.
  • the concentration of the positive electrode active material is 1.0 mol / L, and the concentration of the negative electrode active material is 1.0 mol / L. Further, the lower limit of the optimum SOC range of the positive electrode electrolyte is 10%, and the upper limit is 20%. The lower limit of the optimum SOC range of the negative electrode electrolyte is 30%, and the upper limit is 88%.
  • the discharge capacity under this condition was calculated in the same manner as in the trial calculation example 1. The discharge capacity was calculated for each of the following cases. Table 2 shows the discharge capacity in each case.
  • the cases (e) and (g) cannot be charged or discharged because the SOC utilization range of the positive electrode electrolyte or the negative electrode electrolyte is out of the optimum SOC range.
  • the discharge capacity can be increased in the case (h) in which the liquid volume ratio between the positive electrode electrolyte and the negative electrode electrolyte is 5.0 and the SOC of the mixed electrolyte is 2%. ..
  • the concentration of the positive electrode active material is 1.0 mol / L, and the concentration of the negative electrode active material is 1.0 mol / L. Further, the lower limit of the optimum SOC range of the positive electrode electrolyte is 60%, and the upper limit is 80%. The lower limit of the optimum SOC range of the negative electrode electrolyte is 22%, and the upper limit is 43%.
  • the discharge capacity under this condition was calculated in the same manner as in the trial calculation example 1. The discharge capacity was calculated for each of the following cases. Table 3 shows the discharge capacity in each case.
  • cases (i) and (j) cannot be charged or discharged because the SOC utilization range of the positive electrode electrolyte or the negative electrode electrolyte is out of the optimum SOC range.
  • the discharge capacity can be increased in the case (l) in which the liquid volume ratio between the positive electrode electrolyte and the negative electrode electrolyte is 1.05 and the SOC of the mixed electrolyte is 20%. ..
  • the concentration of the positive electrode active material is 1.0 mol / L, and the concentration of the negative electrode active material is 1.0 mol / L. Further, the lower limit of the optimum SOC range of the positive electrode electrolyte is 30%, and the upper limit is 40%. The lower limit of the optimum SOC range of the negative electrode electrolyte is 30%, and the upper limit is 80%.
  • the discharge capacity under this condition was calculated in the same manner as in the trial calculation example 1. The discharge capacity was calculated for each of the following cases. Table 4 shows the discharge capacity in each case.
  • the cases (n) and (o) cannot be charged or discharged because the SOC utilization range of the positive electrode electrolyte or the negative electrode electrolyte is out of the optimum SOC range.
  • the discharge capacity can be increased in the case (p) in which the liquid volume ratio between the positive electrode electrolyte and the negative electrode electrolyte is 5.0 and the SOC of the mixed electrolyte is 20%. ..
  • the concentration of the positive electrode active material is 1.0 mol / L, and the concentration of the negative electrode active material is 1.05 mol / L. Further, the lower limit of the optimum SOC range of the positive electrode electrolyte is 20%, and the upper limit is 80%. The lower limit of the optimum SOC range of the negative electrode electrolyte is 16.1%, and the upper limit is 76.1%.
  • the discharge capacity under this condition was calculated in the same manner as in the trial calculation example 1. The discharge capacity was determined for each of the cases (a) to (d) above. Table 5 shows the discharge capacity in each case.
  • the discharge capacity can be increased in the case (d) in which the liquid volume ratio between the positive electrode electrolyte and the negative electrode electrolyte is 1.05 and the SOC of the mixed electrolyte is 2%. ..
  • the concentration of the positive electrode active material is 1.0 mol / L, and the concentration of the negative electrode active material is 5.0 mol / L. Further, the lower limit of the optimum SOC range of the positive electrode electrolyte is 20%, and the upper limit is 80%. The lower limit of the optimum SOC range of the negative electrode electrolyte is 17.6%, and the upper limit is 77.6%.
  • the discharge capacity under this condition was calculated in the same manner as in the trial calculation example 1. The discharge capacity was determined for each of the above cases (e) to (h). Table 6 shows the discharge capacity in each case.
  • the cases (e) and (g) cannot be charged or discharged because the SOC utilization range of the positive electrode electrolyte or the negative electrode electrolyte is out of the optimum SOC range.
  • the discharge capacity can be increased in the case (h) in which the liquid volume ratio between the positive electrode electrolyte and the negative electrode electrolyte is 5.0 and the SOC of the mixed electrolyte is 2%. ..
  • the concentration of the positive electrode active material is 1.0 mol / L, and the concentration of the negative electrode active material is 1.05 mol / L. Further, the lower limit of the optimum SOC range of the positive electrode electrolyte is 50%, and the upper limit is 80%. The lower limit of the optimum SOC range of the negative electrode electrolyte is 11%, and the upper limit is 41%.
  • the discharge capacity under this condition was calculated in the same manner as in the trial calculation example 1. The discharge capacity was determined for each of the cases (i) to (l) above. Table 7 shows the discharge capacity in each case.
  • cases (i) and (j) cannot be charged or discharged because the SOC utilization range of the positive electrode electrolyte or the negative electrode electrolyte is out of the optimum SOC range.
  • the discharge capacity can be increased in the case (l) in which the liquid volume ratio between the positive electrode electrolyte and the negative electrode electrolyte is 1.05 and the SOC of the mixed electrolyte is 20%. ..
  • the concentration of the positive electrode active material is 1.0 mol / L, and the concentration of the negative electrode active material is 5.0 mol / L. Further, the lower limit of the optimum SOC range of the positive electrode electrolyte is 50%, and the upper limit is 80%. The lower limit of the optimum SOC range of the negative electrode electrolyte is 26%, and the upper limit is 56%.
  • the discharge capacity under this condition was calculated in the same manner as in the trial calculation example 1. The discharge capacity was determined for each of the above cases (m) to (p). Table 8 shows the discharge capacity in each case.
  • the cases (m) and (o) cannot be charged or discharged because the SOC utilization range of the positive electrode electrolyte or the negative electrode electrolyte is out of the optimum SOC range.
  • the discharge capacity can be increased in the case (p) in which the liquid volume ratio between the positive electrode electrolyte and the negative electrode electrolyte is 5.0 and the SOC of the mixed electrolyte is 20%. ..
  • the liquid volume ratio between the positive electrode electrolyte and the negative electrode electrolyte is 1.05 or more and 5.0 or less, and the SOC of the mixed electrolyte is 2% or more. It can be seen that the discharge capacity of the RF battery can be improved by setting it to 20% or less.
  • the above-mentioned trial calculation example shows an example. In the RF battery, the liquid amount ratio and the SOC of the mixed electrolytic solution are set within the above-mentioned specific ranges according to the concentration of each active material of the positive electrode electrolytic solution and the negative electrode electrolytic solution and the usage range of the SOC. It is possible to increase the discharge capacity in the state. That is, the effect of improving the energy density can be obtained.
  • Redox flow battery (RF battery) 2 Positive electrode electrolyte, 3 Negative electrode electrolyte 10 Battery cell 101 Diaphragm, 102 Positive cell, 103 Negative cell 104 Positive electrode, 105 Negative electrode 12 Positive electrode tank, 13 Negative electrode tank 108, 109 Outward piping, 110, 111 Return piping 112, 113 Pump 100 Cell stack 20 Sub-stack 21 Supply / discharge plate 22 End plate, 23 Tightening mechanism 30 Cell frame 31 Bipolar plate, 32 Frame 33, 34 Liquid supply manifold, 35, 36 Discharge manifold 33s, 34s Liquid supply slit, 35s , 36s Drainage slit 80 AC / DC converter, 81 Substation equipment 90 Power system, 91 Power generation unit, 92 Load

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