WO2019151454A1 - Flow battery - Google Patents

Flow battery Download PDF

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Publication number
WO2019151454A1
WO2019151454A1 PCT/JP2019/003516 JP2019003516W WO2019151454A1 WO 2019151454 A1 WO2019151454 A1 WO 2019151454A1 JP 2019003516 W JP2019003516 W JP 2019003516W WO 2019151454 A1 WO2019151454 A1 WO 2019151454A1
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WIPO (PCT)
Prior art keywords
negative electrode
positive electrode
electrolytic solution
flow battery
zinc
Prior art date
Application number
PCT/JP2019/003516
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French (fr)
Japanese (ja)
Inventor
彩珠沙 小▲柳▼
智之 小野
丈司 大隈
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京セラ株式会社
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Publication of WO2019151454A1 publication Critical patent/WO2019151454A1/en

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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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/24—Alkaline accumulators
    • H01M10/26—Selection of materials as electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/24—Alkaline accumulators
    • H01M10/28—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/24—Alkaline accumulators
    • H01M10/30—Nickel accumulators
    • 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
    • Y02E60/10—Energy storage using 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the disclosed embodiment relates to a flow battery.
  • a flow battery in which an electrolytic solution containing tetrahydroxyzincate ions ([Zn (OH) 4 ] 2 ⁇ ) is circulated between a positive electrode and a negative electrode (see, for example, Non-Patent Document 1). .
  • the flow battery includes a positive electrode and a negative electrode, an electrolytic solution, and a flow device.
  • the electrolytic solution contacts the positive electrode and the negative electrode.
  • the flow device causes the electrolyte solution to flow.
  • the electrolytic solution is an alkaline aqueous solution containing 8 mol or more of potassium component and 1.3 mol or more of zinc component per dm 3 .
  • FIG. 1 is a diagram schematically illustrating the flow battery according to the first embodiment.
  • FIG. 2 is a diagram illustrating an example of connection between electrodes of the flow battery according to the first embodiment.
  • FIG. 3 is a diagram schematically illustrating the flow battery according to the second embodiment.
  • FIG. 4 is a diagram illustrating an example of connection between electrodes of the flow battery according to the second embodiment.
  • FIG. 5 is a diagram schematically illustrating a flow battery according to the third embodiment.
  • FIG. 6 is a diagram showing the result of evaluating zinc adhering to the negative electrode by charging.
  • FIG. 1 is a diagram schematically illustrating the flow battery according to the first embodiment.
  • the flow battery 1 shown in FIG. 1 includes a reaction unit 10 and a generation unit 9 housed in a housing 17 and a supply unit 14.
  • the reaction unit 10 includes a positive electrode 2, a negative electrode 3, diaphragms 4 and 5, an electrolytic solution 6, and a powder 7.
  • the flow battery 1 is a device that causes the electrolytic solution 6 accommodated in the reaction unit 10 to flow by causing the bubbles 8 generated in the generating unit 9 to float in the electrolytic solution 6.
  • the generating unit 9 is an example of a flow device.
  • FIG. 1 shows a three-dimensional orthogonal coordinate system including a Z-axis having a vertical upward direction as a positive direction and a vertical downward direction as a negative direction.
  • Such an orthogonal coordinate system may also be shown in other drawings used in the following description.
  • the positive electrode 2 is a conductive member containing, for example, a nickel compound, a manganese compound or a cobalt compound as a positive electrode active material.
  • a nickel compound for example, nickel oxyhydroxide, nickel hydroxide, cobalt compound-containing nickel hydroxide and the like can be used.
  • the manganese compound for example, manganese dioxide can be used.
  • the cobalt compound for example, cobalt hydroxide and cobalt oxyhydroxide can be used.
  • the positive electrode 2 may include graphite, carbon black, conductive resin, and the like.
  • the positive electrode 2 may be nickel metal, cobalt metal, manganese metal, or an alloy thereof.
  • the positive electrode 2 includes, for example, the above-described positive electrode active material, conductor, and other additives as a plurality of granular materials.
  • the positive electrode 2 is made of, for example, a paste-like positive electrode material containing a granular active material and a conductor blended at a predetermined ratio together with a binder that contributes to shape retention. It is a product that is press-fitted into a foam metal having a property, molded into a desired shape, and dried.
  • the negative electrode 3 contains a negative electrode active material as a metal.
  • a metal plate such as stainless steel or copper, or a surface obtained by plating the surface of the stainless steel or copper plate with nickel, tin, or zinc can be used. Moreover, you may use as the negative electrode 3 what the plated surface partially oxidized.
  • the negative electrode 3 includes a negative electrode 3a and a negative electrode 3b arranged to face each other with the positive electrode 2 interposed therebetween.
  • the positive electrode 2 and the negative electrode 3 are arranged so that the negative electrode 3a, the positive electrode 2, and the negative electrode 3b are sequentially arranged along the Y-axis direction at a predetermined interval.
  • the diaphragms 4 and 5 are arranged so as to sandwich the thickness direction of the positive electrode 2, that is, both sides in the Y-axis direction.
  • the diaphragms 4 and 5 are made of a material that allows movement of ions contained in the electrolytic solution 6.
  • examples of the material for the diaphragms 4 and 5 include an anion conductive material such that the diaphragms 4 and 5 have hydroxide ion conductivity.
  • the anion conductive material include a gel-like anion conductive material having a three-dimensional structure such as an organic hydrogel, or a solid polymer type anion conductive material.
  • the solid polymer type anion conductive material includes, for example, a polymer and at least one element selected from Group 1 to Group 17 of the periodic table, oxide, hydroxide, layered double hydroxide And at least one compound selected from the group consisting of a sulfate compound and a phosphate compound.
  • the diaphragms 4 and 5 are preferably composed of a dense material so as to suppress permeation of a metal ion complex such as [Zn (OH) 4 ] 2 ⁇ having an ionic radius larger than hydroxide ions. It has a predetermined thickness.
  • the dense material include a material having a relative density calculated by Archimedes method of 90% or more, more preferably 92% or more, and still more preferably 95% or more.
  • the predetermined thickness is, for example, 10 ⁇ m to 1000 ⁇ m, more preferably 50 ⁇ m to 500 ⁇ m.
  • the electrolytic solution 6 is an alkaline aqueous solution containing zinc species.
  • the zinc species in the electrolytic solution 6 is dissolved in the electrolytic solution 6 as [Zn (OH) 4 ] 2 ⁇ .
  • the electrolytic solution 6 for example, a solution obtained by dissolving a zinc species in an alkaline aqueous solution containing K + or OH ⁇ can be used.
  • the electrolytic solution 6 for example, under the condition that the current density is 250 A ⁇ m ⁇ 2 and the energy density is 15 Wh ⁇ dm ⁇ 3 , 13.9 mol or more of potassium component and 2.2 mol or more of dm 3 are used.
  • An alkaline aqueous solution containing a zinc component can be used.
  • the potassium component for example, potassium hydroxide can be used.
  • the zinc component for example, zinc oxide or zinc hydroxide can be used.
  • zinc oxide is added so that 2.2 mol of zinc component ([Zn (OH) 4 ] 2 ⁇ ) is contained in 1 dm 3 of deionized water, and then 13.9 mol of potassium component
  • An alkaline aqueous solution obtained by adding, stirring, and dissolving potassium hydroxide in approximately half amounts so as to contain (K + ) while heating as necessary can be used as the electrolyte 6. Further, the obtained alkaline aqueous solution may be diluted to be the electrolytic solution 6.
  • the electrolytic solution 6 having different potassium component and zinc component contents depending on the charging conditions such as current density and energy density, conduction between the negative electrode 3 and the positive electrode 2 can be reduced.
  • the saturation dissolution amount of zinc species varies depending on the concentration of potassium hydroxide.
  • the increase rate of the saturated dissolution amount of the zinc species when potassium hydroxide is increased is larger than the increase rate of the potassium hydroxide amount. That is, the saturated dissolution amount of the zinc species is larger than the proportionality with respect to the potassium hydroxide amount. For this reason, an electrolyte solution 6 having a higher potassium hydroxide concentration than the desired electrolyte solution 6 is prepared, and further zinc species are dissolved to an amount higher than the desired concentration, and then diluted with deionized water to saturate the zinc species.
  • the electrolytic solution 6 that has been dissolved up to the dissolved amount can be produced. Moreover, the supersaturated electrolyte solution 6 in which the zinc species is dissolved in a larger amount than the saturated dissolution amount can be produced by the same method. When the supersaturated electrolytic solution 6 is left for a long period of time, zinc species are deposited.
  • the powder 7 contains zinc.
  • the powder 7 is, for example, zinc oxide, zinc hydroxide or the like processed or generated into a powder form.
  • the powder 7 is easily dissolved in the alkaline aqueous solution, but is not dissolved in the zinc-saturated electrolytic solution 6 but is dispersed or floated, and is mixed in the electrolytic solution 6 in a partially settled state.
  • the electrolytic solution 6 is left standing for a long time, most of the powder 7 may settle in the electrolytic solution 6, but if the electrolytic solution 6 causes convection, the powder 7 is settled.
  • a part of the powder 7 is dispersed or suspended in the electrolytic solution 6. That is, the powder 7 exists so as to be movable in the electrolytic solution 6.
  • the phrase “movable” does not mean that the powder 7 can move only in a local space formed between other surrounding powders 7, but the powder 7 can be moved to another position in the electrolytic solution 6. It represents that the powder 7 is exposed to the electrolyte solution 6 other than the original position by moving. Further, the movable category includes that the powder 7 can move to the vicinity of both the positive electrode 2 and the negative electrode 3, and the powder 7 almost everywhere in the electrolyte 6 existing in the housing 17. It is included that can be moved. When [Zn (OH) 4 ] 2 ⁇ which is a zinc species dissolved in the electrolytic solution 6 is consumed, the powder 7 mixed in the electrolytic solution 6 maintains an equilibrium state between the powder 7 and the electrolytic solution 6. The zinc species dissolved in the electrolyte solution 6 is dissolved so as to approach saturation.
  • the bubble 8 is composed of a gas inert to the positive electrode 2, the negative electrode 3, and the electrolytic solution 6, for example.
  • a gas examples include nitrogen gas, helium gas, neon gas, and argon gas.
  • inert gas bubbles 8 in the electrolytic solution 6 denaturation of the electrolytic solution 6 can be reduced. Further, for example, it is possible to reduce deterioration of the electrolytic solution 6 that is an alkaline aqueous solution containing zinc species, and to keep the ionic conductivity of the electrolytic solution 6 high.
  • the gas may contain air.
  • the bubbles 8 generated by the gas supplied from the generating unit 9 into the electrolytic solution 6 are between the electrodes arranged at a predetermined interval, more specifically, between the negative electrode 3a and the positive electrode 2, and between the positive electrode 2 and the negative electrode 3b. And float in the electrolytic solution 6 respectively.
  • the gas floating in the electrolytic solution 6 as bubbles 8 disappears at the liquid level 6 a of the electrolytic solution 6, and the gas layer 13 is formed between the upper plate 18 and the liquid level 6 a of the electrolytic solution 6.
  • the electrode reaction in the flow battery 1 will be described by taking a nickel zinc battery to which nickel hydroxide is applied as a positive electrode active material as an example.
  • the reaction formulas at the positive electrode 2 and the negative electrode 3 during charging are as follows.
  • Positive electrode Ni (OH) 2 + OH ⁇ ⁇ NiOOH + H 2 O + e ⁇
  • the electrolytic solution 6 after discharge has a high zinc species concentration and is close to the saturation amount.
  • the electrolyte solution 6 prepared first is obtained by simply dissolving zinc oxide, the zinc species concentration is lower than the saturation amount, and dendrites are likely to grow. For this reason, as the electrolytic solution 6 that is initially put in the flow battery 1, it is preferable to use a solution that is produced by the above-described method or the like and that is substantially saturated or supersaturated.
  • the powder 7 containing zinc is mixed in the electrolytic solution 6 and gas is supplied into the electrolytic solution 6 from the discharge port 9a of the generating unit 9 to generate the bubbles 8. .
  • the bubbles 8 float in the electrolytic solution 6 from the lower side of the housing 17 to the upper side between the negative electrode 3a and the positive electrode 2 and between the positive electrode 2 and the negative electrode 3b.
  • the powder 7 includes metal zinc, calcium zincate, zinc carbonate, zinc sulfate, zinc chloride and the like in addition to zinc oxide and zinc hydroxide, and zinc oxide and zinc hydroxide are preferred.
  • the electrolytic solution 6 is already in a saturated state.
  • (OH) 4 ] 2- precipitates ZnO.
  • the zinc consumed in the negative electrode 3 is zinc deposited on the surface of the negative electrode 3 during charging.
  • a so-called shape change in which the surface shape of the negative electrode 3 changes does not occur.
  • the time-dependent deterioration of the negative electrode 3 can be reduced.
  • the precipitated [Zn (OH) 4 ] 2 ⁇ may be Zn (OH) 2 or a mixture of ZnO and Zn (OH) 2. .
  • the zinc deposited in the form of moss is bulky as compared with, for example, zinc deposited in a normal state having a bulk density of about 4120 kg ⁇ m ⁇ 3, so that the gap between the positive electrode 2 and the negative electrode 3 is reduced, so that the bubbles 8 and the electrolyte solution 6 is hindered, and the electrolytic solution 6 accommodated in the reaction unit 10 tends to stay. Further, when the mossy zinc deposited on the negative electrode 3 reaches the positive electrode 2, the negative electrode 3 and the positive electrode 2 are electrically connected.
  • the amount of bubbles 8, that is to say from the generator 9 2 dm per the supply amount of the gas for 1 minute 3 ejected into the reaction section 10 or less, especially 1 dm 3 or more 2 dm 3 or less.
  • the generation unit 9 is disposed below the reaction unit 10.
  • the generating unit 9 is hollow so as to temporarily store a gas supplied from a supply unit 14 to be described later.
  • the inner bottom 10 e of the reaction unit 10 is disposed so as to cover the hollow portion of the generation unit 9, and also serves as a top plate of the generation unit 9.
  • the inner bottom 10e has a plurality of discharge ports 9a arranged along the X-axis direction and the Y-axis direction.
  • the generating unit 9 generates bubbles 8 in the electrolytic solution 6 by discharging the gas supplied from the supplying unit 14 from the discharge port 9a.
  • the discharge port 9a has a diameter of 0.05 mm or more and 0.5 mm or less, for example. By defining the diameter of the discharge port 9a in this way, it is possible to reduce the problem that the electrolytic solution 6 and the powder 7 enter the hollow portion inside the generating unit 9 from the discharge port 9a. Further, it is possible to give a pressure loss suitable for generating the bubbles 8 to the gas discharged from the discharge port 9a.
  • the interval (pitch) along the X-axis direction of the discharge ports 9a is, for example, 2.5 mm or more and 50 mm or less, and may be 10 mm or less.
  • the discharge port 9a is not limited in size and interval as long as the generated bubbles 8 can be appropriately flowed between the positive electrode 2 and the negative electrode 3 facing each other.
  • the housing 17 and the upper plate 18 are made of a resin material having alkali resistance and insulation, such as polystyrene, polypropylene, polyethylene terephthalate, polytetrafluoroethylene, polyvinyl chloride, and the like.
  • the housing 17 and the upper plate 18 are preferably made of the same material, but may be made of different materials.
  • the generation unit 9 may be disposed inside the reaction unit 10.
  • the supply unit 14 supplies the gas collected from the inside of the housing 17 through the pipe 16 to the generation unit 9 through the pipe 15.
  • the supply unit 14 is, for example, a pump (gas pump), a compressor, or a blower that can transfer gas. If the airtightness of the supply unit 14 is increased, the power generation performance of the flow battery 1 is less likely to decrease due to leakage of gas or water vapor derived from the electrolyte 6 to the outside.
  • FIG. 2 is a diagram illustrating an example of connection between electrodes of the flow battery 1 according to the first embodiment.
  • the negative electrode 3a and the negative electrode 3b are connected in parallel.
  • the electrodes of the flow battery 1 can be appropriately connected and used even when the total number of the positive electrodes 2 and the negative electrodes 3 is different.
  • the flow battery 1 includes the negative electrodes 3a and 3b arranged so as to face each other with the positive electrode 2 interposed therebetween.
  • the current density per negative electrode is compared with the flow battery in which the positive electrode 2 and the negative electrode 3 correspond 1: 1. Decreases. For this reason, according to the flow battery 1 which concerns on 1st Embodiment, since the production
  • the total of three electrodes are configured such that the negative electrodes 3 and the positive electrodes 2 are alternately arranged.
  • the present invention is not limited to this, and one positive electrode 2 and one negative electrode 3 are provided. You may arrange them one by one.
  • both ends are configured to be the negative electrode 3, but the present invention is not limited thereto, and both ends may be configured to be the positive electrode 2.
  • FIG. 3 is a diagram schematically illustrating the flow battery according to the second embodiment.
  • a flow battery 1A shown in FIG. 3 has the same configuration as the flow battery 1 according to the first embodiment except that the number of positive electrodes 2 and negative electrodes 3 and the arrangement of the discharge ports 9a are different.
  • the positive electrode 2 includes positive electrodes 2A and 2B.
  • the negative electrode 3 includes negative electrodes 3A, 3B and 3C.
  • the positive electrode 2 and the negative electrode 3 are arranged so that the negative electrode 3A, the positive electrode 2A, the negative electrode 3B, the positive electrode 2B, and the negative electrode 3C are arranged in order along the Y-axis direction at predetermined intervals.
  • the discharge port 9a is located between the adjacent positive electrode 2 and the negative electrode 3, that is, between the negative electrode 3A and the positive electrode 2A, between the positive electrode 2A and the negative electrode 3B, between the negative electrode 3B and the positive electrode 2B, and between the positive electrode 2B and the negative electrode. It arrange
  • FIG. 4 is a diagram for explaining an example of connection between electrodes of the flow battery 1A according to the second embodiment.
  • the positive electrodes 2A and 2B are connected in parallel.
  • the negative electrodes 3A, 3B, and 3C are connected in parallel.
  • the electrodes of the flow battery 1A can be appropriately connected and used.
  • the electrolyte solution 6 according to the energy density can be used.
  • the electrolytic solution 6 for example, under the condition that the current density is 225 A ⁇ m ⁇ 2 and the energy density is 60 Wh ⁇ dm ⁇ 3 , 15.5 mol or more potassium component and 3.2 mol or more per dm 3 are used.
  • An alkaline aqueous solution containing a zinc component can be used.
  • a total of five electrodes are configured such that the negative electrode 3 and the positive electrode 2 are alternately arranged.
  • the present invention is not limited thereto, and six or more electrodes are alternately arranged. Also good.
  • both ends are configured to be the negative electrode 3, but the same number of the negative electrodes 3 and the positive electrodes 2 are alternately arranged so that one is the positive electrode 2 and the other is the negative electrode 3. May be.
  • FIG. 5 is a diagram schematically illustrating a flow battery according to the third embodiment.
  • the flow battery 1B shown in FIG. 5 is the same as that of the first embodiment except that the generator 9, the supply unit 14, and the pipes 15 and 16 shown in FIG. 1 are replaced with a supply part 14 a and pipes 15 a and 16 a.
  • the flow battery 1 has the same configuration.
  • the supply unit 14a supplies the electrolytic solution 6 mixed with the powder 7 collected from the inside of the casing 17 through the pipe 16a to the lower part of the casing 17 through the pipe 15a.
  • the supply unit 14a is an example of a flow device.
  • the supply unit 14a is, for example, a pump capable of transferring the electrolytic solution 6. If the airtightness of the supply unit 14a is increased, the power generation performance of the flow battery 1B is less likely to decrease due to leakage of the powder 7 and the electrolyte 6 to the outside. And the electrolyte solution 6 sent to the inside of the housing
  • the conduction between the negative electrode 3 and the positive electrode 2 can be reduced by adjusting the content of the potassium component and the zinc component in the electrolytic solution 6.
  • the opening connected to the pipe 16a is provided on the inner wall 10b facing the main surface of each electrode, that is, the end of the reaction unit 10 on the Y axis direction side.
  • the present invention may be provided at the end on the X axis direction side.
  • the supply unit 14a supplies the electrolytic solution 6 in which the powder 7 is mixed to the casing 17, but the supply unit 14a is not limited to this and may supply only the electrolytic solution 6. .
  • a tank for temporarily storing the electrolytic solution 6 in which the powder 7 is mixed is provided in the middle of the pipe 16a, and the concentration of [Zn (OH) 4 ] 2 ⁇ dissolved in the electrolytic solution 6 is set inside the tank. It is good also as adjusting.
  • the powder 7 is described as being mixed in the electrolytic solution 6.
  • the zinc component dissolved in the electrolytic solution 6 may be in a saturated state or a concentration lower than that in the saturated state.
  • the electrolyte solution 6 may be one in which a zinc component is dissolved so as to be in a supersaturated state.
  • the electrolytic solution 6 containing a high concentration of [Zn (OH) 4 ] 2 ⁇ between the positive electrode 2 and the negative electrode 3 the upper ends of the positive electrode 2 and the negative electrode 3 are connected to the electrolytic solution 6. You may adjust the quantity of the electrolyte solution 6 so that it may be arrange
  • the diaphragms 4 and 5 have been described as being disposed so as to sandwich both sides in the thickness direction of the positive electrode 2, but the present invention is not limited thereto, and is disposed between the positive electrode 2 and the negative electrode 3. And the positive electrode 2 may be covered.
  • the supply parts 14 and 14a may be always operated, from the viewpoint of reducing power consumption, the supply rate of the gas or the electrolyte solution 6 may be lowered during discharging than during charging.
  • FIG. 6 is a diagram showing the result of evaluating zinc adhering to the negative electrode by charging.
  • electrolytes 6 having different concentrations of potassium hydroxide (KOH) and Zn ions ([Zn (OH) 4 ] 2 ⁇ ) contained in deionized water were used.
  • KOH potassium hydroxide
  • Zn ions [Zn (OH) 4 ] 2 ⁇
  • dissolve in the electrolyte solution 6 remains, and the electrolyte solution 6 having the ion concentration shown in FIG. Sample No. 3 and 6, ZnO was further added at a rate of 1.8 mol with respect to 1 dm 3 of the electrolyte 6 as the powder 7.
  • the sample No. 2 is obtained until the battery capacity reaches 100%.
  • zinc deposited on the surface of the negative electrode 3 was evaluated. Sample No. In the flow batteries 1A of 9 and 10, since the zinc component which did not melt
  • dendrite is not observed on the surface of the negative electrode 3, and particularly good ones are marked with ⁇ , and dendrite is not visually observed, but when dendritic is magnified 100 times with an SEM (Scanning Electron Microscope) or an optical microscope. Evaluation was made on a four-point scale, with ⁇ being observed, dendrite visually observed, ⁇ when not reaching the positive electrode, and x when some of the grown dendrite had reached the positive electrode 2 did.
  • SEM Scnning Electron Microscope
  • the electrolytic solution 6 containing a predetermined amount of KOH as a potassium component and [Zn (OH) 4 ] 2 ⁇ as a zinc component, respectively.
  • KOH potassium component
  • [Zn (OH) 4 ] 2 ⁇ as a zinc component

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Abstract

A flow battery according to an embodiment comprises a positive electrode, a negative electrode, an electrolyte, and a flow device. The electrolyte contacts the positive electrode and the negative electrode. The flow device causes the electrolyte to flow. The electrolyte is an alkaline aqueous solution containing at least 8 moles per dm3 of a potassium component and at least 1.3 moles per dm3 of a zinc component.

Description

フロー電池Flow battery
　開示の実施形態は、フロー電池に関する。 The disclosed embodiment relates to a flow battery.
　従来、正極と負極との間に、テトラヒドロキシ亜鉛酸イオン（［Ｚｎ（ＯＨ）４］２－）を含有する電解液を循環させるフロー電池が知られている（例えば、非特許文献１参照）。 Conventionally, a flow battery is known in which an electrolytic solution containing tetrahydroxyzincate ions ([Zn (OH) 4 ] 2− ) is circulated between a positive electrode and a negative electrode (see, for example, Non-Patent Document 1). .
　また、亜鉛種などの活物質を含む負極を、選択的イオン伝導性を有するイオン伝導層で覆うことでデンドライトの成長を抑制する技術が提案されている（例えば、特許文献１参照）。 Also, a technique for suppressing the growth of dendrites by covering a negative electrode containing an active material such as zinc species with an ion conductive layer having selective ion conductivity has been proposed (for example, see Patent Document 1).
特開２０１５－１８５２５９号公報JP2015-185259A
　実施形態の一態様に係るフロー電池は、正極および負極と、電解液と、流動装置とを備える。電解液は、前記正極および前記負極に接触する。流動装置は、前記電解液を流動させる。前記電解液は、１ｄｍ３当たり８ｍｏｌ以上のカリウム成分と１．３ｍｏｌ以上の亜鉛成分とを含有するアルカリ水溶液である。 The flow battery according to one aspect of the embodiment includes a positive electrode and a negative electrode, an electrolytic solution, and a flow device. The electrolytic solution contacts the positive electrode and the negative electrode. The flow device causes the electrolyte solution to flow. The electrolytic solution is an alkaline aqueous solution containing 8 mol or more of potassium component and 1.3 mol or more of zinc component per dm 3 .
図１は、第１の実施形態に係るフロー電池の概略を示す図である。FIG. 1 is a diagram schematically illustrating the flow battery according to the first embodiment. 図２は、第１の実施形態に係るフロー電池の電極間の接続の一例について説明する図である。FIG. 2 is a diagram illustrating an example of connection between electrodes of the flow battery according to the first embodiment. 図３は、第２の実施形態に係るフロー電池の概略を示す図である。FIG. 3 is a diagram schematically illustrating the flow battery according to the second embodiment. 図４は、第２の実施形態に係るフロー電池の電極間の接続の一例について説明する図である。FIG. 4 is a diagram illustrating an example of connection between electrodes of the flow battery according to the second embodiment. 図５は、第３の実施形態に係るフロー電池の概略を示す図である。FIG. 5 is a diagram schematically illustrating a flow battery according to the third embodiment. 図６は、充電により負極に付着する亜鉛を評価した結果を示す図である。FIG. 6 is a diagram showing the result of evaluating zinc adhering to the negative electrode by charging.
　以下、添付図面を参照して、本願の開示するフロー電池の実施形態を詳細に説明する。なお、以下に示す実施形態によりこの発明が限定されるものではない。 Hereinafter, embodiments of a flow battery disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.
＜第１の実施形態＞
　図１は、第１の実施形態に係るフロー電池の概略を示す図である。図１に示すフロー電池１は、筐体１７に収容された反応部１０および発生部９と、供給部１４とを備える。反応部１０は、正極２と、負極３と、隔膜４，５と、電解液６と、粉末７とを備える。フロー電池１は、発生部９で発生した気泡８を電解液６中で浮上させることにより反応部１０内に収容された電解液６を流動させる装置である。発生部９は、流動装置の一例である。 <First Embodiment>
FIG. 1 is a diagram schematically illustrating the flow battery according to the first embodiment. The flow battery 1 shown in FIG. 1 includes a reaction unit 10 and a generation unit 9 housed in a housing 17 and a supply unit 14. The reaction unit 10 includes a positive electrode 2, a negative electrode 3, diaphragms 4 and 5, an electrolytic solution 6, and a powder 7. The flow battery 1 is a device that causes the electrolytic solution 6 accommodated in the reaction unit 10 to flow by causing the bubbles 8 generated in the generating unit 9 to float in the electrolytic solution 6. The generating unit 9 is an example of a flow device.
　なお、説明を分かりやすくするために、図１には、鉛直上向きを正方向とし、鉛直下向きを負方向とするＺ軸を含む３次元の直交座標系を図示している。かかる直交座標系は、後述の説明に用いる他の図面でも示す場合がある。 For easy understanding, FIG. 1 shows a three-dimensional orthogonal coordinate system including a Z-axis having a vertical upward direction as a positive direction and a vertical downward direction as a negative direction. Such an orthogonal coordinate system may also be shown in other drawings used in the following description.
　正極２は、例えば、ニッケル化合物、マンガン化合物またはコバルト化合物を正極活物質として含有する導電性の部材である。ニッケル化合物は、例えば、オキシ水酸化ニッケル、水酸化ニッケル、コバルト化合物含有水酸化ニッケル等が使用できる。マンガン化合物は、例えば、二酸化マンガン等が使用できる。コバルト化合物は、例えば、水酸化コバルト、オキシ水酸化コバルト等が使用できる。また、正極２は、黒鉛、カーボンブラック、導電性樹脂等を含んでもよい。また、正極２は、ニッケル金属、コバルト金属またはマンガン金属、あるいはそれらの合金であってもよい。 The positive electrode 2 is a conductive member containing, for example, a nickel compound, a manganese compound or a cobalt compound as a positive electrode active material. As the nickel compound, for example, nickel oxyhydroxide, nickel hydroxide, cobalt compound-containing nickel hydroxide and the like can be used. As the manganese compound, for example, manganese dioxide can be used. As the cobalt compound, for example, cobalt hydroxide and cobalt oxyhydroxide can be used. The positive electrode 2 may include graphite, carbon black, conductive resin, and the like. The positive electrode 2 may be nickel metal, cobalt metal, manganese metal, or an alloy thereof.
　また、正極２は、例えば、上記した正極活物質や導電体その他の添加剤を複数の粒状体として含む。具体的には、正極２は、例えば、予め定められた割合で配合された粒状の活物質および導電体を、保形性に寄与するバインダとともに含有するペースト状の正極材料を発泡ニッケルなどの導電性を有する発泡金属へ圧入し、所望の形状に成形し、乾燥させたものである。 The positive electrode 2 includes, for example, the above-described positive electrode active material, conductor, and other additives as a plurality of granular materials. Specifically, the positive electrode 2 is made of, for example, a paste-like positive electrode material containing a granular active material and a conductor blended at a predetermined ratio together with a binder that contributes to shape retention. It is a product that is press-fitted into a foam metal having a property, molded into a desired shape, and dried.
　負極３は、負極活物質を金属として含む。負極３は、例えば、ステンレスや銅などの金属板や、ステンレスや銅板の表面をニッケルやスズ、亜鉛でメッキ処理したものを使用することができる。また、メッキ処理された表面が一部酸化されたものを負極３として使用してもよい。 The negative electrode 3 contains a negative electrode active material as a metal. As the negative electrode 3, for example, a metal plate such as stainless steel or copper, or a surface obtained by plating the surface of the stainless steel or copper plate with nickel, tin, or zinc can be used. Moreover, you may use as the negative electrode 3 what the plated surface partially oxidized.
　負極３は、正極２を挟んで互いに向かい合うように配置された負極３ａおよび負極３ｂを含む。正極２および負極３は、負極３ａと、正極２と、負極３ｂとが予め定められた間隔でＹ軸方向に沿って順に並ぶように配置されている。このように隣り合う正極２と負極３との間隔をそれぞれ設けることにより、正極２と負極３との間における電解液６および気泡８の流通経路が確保される。 The negative electrode 3 includes a negative electrode 3a and a negative electrode 3b arranged to face each other with the positive electrode 2 interposed therebetween. The positive electrode 2 and the negative electrode 3 are arranged so that the negative electrode 3a, the positive electrode 2, and the negative electrode 3b are sequentially arranged along the Y-axis direction at a predetermined interval. Thus, by providing the space | interval of the positive electrode 2 and the negative electrode 3 which adjoin each other, the distribution path of the electrolyte solution 6 and the bubble 8 between the positive electrode 2 and the negative electrode 3 is ensured.
　隔膜４，５は、正極２の厚み方向、すなわちＹ軸方向の両側を挟むように配置される。隔膜４，５は、電解液６に含まれるイオンの移動を許容する材料で構成される。具体的には、隔膜４，５の材料として、例えば、隔膜４，５が水酸化物イオン伝導性を有するように、陰イオン伝導性材料が挙げられる。陰イオン伝導性材料としては、例えば、有機ヒドロゲルのような三次元構造を有するゲル状の陰イオン伝導性材料、または固体高分子型陰イオン伝導性材料などが挙げられる。固体高分子型陰イオン伝導性材料は、例えば、ポリマーと、周期表の第１族～第１７族より選択された少なくとも一種類の元素を含有する、酸化物、水酸化物、層状複水酸化物、硫酸化合物およびリン酸化合物からなる群より選択された少なくとも一つの化合物とを含む。 The diaphragms 4 and 5 are arranged so as to sandwich the thickness direction of the positive electrode 2, that is, both sides in the Y-axis direction. The diaphragms 4 and 5 are made of a material that allows movement of ions contained in the electrolytic solution 6. Specifically, examples of the material for the diaphragms 4 and 5 include an anion conductive material such that the diaphragms 4 and 5 have hydroxide ion conductivity. Examples of the anion conductive material include a gel-like anion conductive material having a three-dimensional structure such as an organic hydrogel, or a solid polymer type anion conductive material. The solid polymer type anion conductive material includes, for example, a polymer and at least one element selected from Group 1 to Group 17 of the periodic table, oxide, hydroxide, layered double hydroxide And at least one compound selected from the group consisting of a sulfate compound and a phosphate compound.
　隔膜４，５は、好ましくは、水酸化物イオンよりも大きいイオン半径を備えた［Ｚｎ（ＯＨ）４］２－等の金属イオン錯体の透過を抑制するように緻密な材料で構成されると共に所定の厚さを有する。緻密な材料としては、例えば、アルキメデス法で算出された９０％以上、より好ましくは９２％以上、さらに好ましくは９５％以上の相対密度を有する材料が挙げられる。所定の厚さは、例えば、１０μｍ～１０００μｍ、より好ましくは５０μｍ～５００μｍである。 The diaphragms 4 and 5 are preferably composed of a dense material so as to suppress permeation of a metal ion complex such as [Zn (OH) 4 ] 2− having an ionic radius larger than hydroxide ions. It has a predetermined thickness. Examples of the dense material include a material having a relative density calculated by Archimedes method of 90% or more, more preferably 92% or more, and still more preferably 95% or more. The predetermined thickness is, for example, 10 μm to 1000 μm, more preferably 50 μm to 500 μm.
　この場合には、充電の際に、負極３ａ，３ｂにおいて析出する亜鉛がデンドライト（針状結晶）として成長し、隔膜４，５を貫通することを低減することができる。その結果、互いに向かい合う負極３と正極２との間の導通を低減することができる。 In this case, it is possible to reduce that zinc deposited on the negative electrodes 3a and 3b grows as dendrites (needle crystals) and penetrates the diaphragms 4 and 5 during charging. As a result, conduction between the negative electrode 3 and the positive electrode 2 facing each other can be reduced.
　電解液６は、亜鉛種を含有するアルカリ水溶液である。電解液６中の亜鉛種は、［Ｚｎ（ＯＨ）４］２－として電解液６中に溶存している。電解液６は、例えば、Ｋ＋やＯＨ－を含むアルカリ水溶液に亜鉛種を溶解させたものを使用することができる。ここで、電解液６としては、例えば、電流密度が２５０Ａ・ｍ－２、エネルギー密度が１５Ｗｈ・ｄｍ－３となる条件下において、１ｄｍ３当たり１３．９ｍｏｌ以上のカリウム成分と２．２ｍｏｌ以上の亜鉛成分とを含有するアルカリ水溶液を使用することができる。カリウム成分としては、例えば水酸化カリウムを使用することができる。また、亜鉛成分としては、例えば酸化亜鉛または水酸化亜鉛を使用することができる。 The electrolytic solution 6 is an alkaline aqueous solution containing zinc species. The zinc species in the electrolytic solution 6 is dissolved in the electrolytic solution 6 as [Zn (OH) 4 ] 2− . As the electrolytic solution 6, for example, a solution obtained by dissolving a zinc species in an alkaline aqueous solution containing K + or OH − can be used. Here, as the electrolytic solution 6, for example, under the condition that the current density is 250 A · m −2 and the energy density is 15 Wh · dm −3 , 13.9 mol or more of potassium component and 2.2 mol or more of dm 3 are used. An alkaline aqueous solution containing a zinc component can be used. As the potassium component, for example, potassium hydroxide can be used. Further, as the zinc component, for example, zinc oxide or zinc hydroxide can be used.
　具体的には、例えば、脱イオン水１ｄｍ３に対し、２．２ｍｏｌの亜鉛成分（［Ｚｎ（ＯＨ）４］２－）が含まれるように酸化亜鉛を添加し、次いで１３．９ｍｏｌのカリウム成分（Ｋ＋）が含まれるように水酸化カリウムを概ね半量ずつ、必要に応じて加温しながら添加および攪拌し、溶解することで得られるアルカリ性水溶液を電解液６として使用することができる。また、得られたアルカリ性水溶液を希釈して電解液６としてもよい。例えば、電流密度が１２５Ａ・ｍ－２、エネルギー密度が１５Ｗｈ・ｄｍ－３となる条件下においては、１ｄｍ３当たり８ｍｏｌ以上のカリウム成分と１．３ｍｏｌ以上の亜鉛成分とを含有するように脱イオン水で希釈したものを電解液６として使用することができる。さらに、酸素発生抑制を目的に、水酸化リチウムや水酸化ナトリウムなどのアルカリ金属を添加してもよい。このように、電流密度およびエネルギー密度といった充電条件に応じてカリウム成分および亜鉛成分の含有量が異なる電解液６を使用することにより、負極３と正極２との導通を低減することができる。 Specifically, for example, zinc oxide is added so that 2.2 mol of zinc component ([Zn (OH) 4 ] 2− ) is contained in 1 dm 3 of deionized water, and then 13.9 mol of potassium component An alkaline aqueous solution obtained by adding, stirring, and dissolving potassium hydroxide in approximately half amounts so as to contain (K + ) while heating as necessary can be used as the electrolyte 6. Further, the obtained alkaline aqueous solution may be diluted to be the electrolytic solution 6. For example, under conditions where the current density is 125 A · m −2 and the energy density is 15 Wh · dm −3 , deionization is performed so as to contain 8 mol or more of potassium component and 1.3 mol or more of zinc component per dm 3. What was diluted with water can be used as the electrolyte solution 6. Furthermore, an alkali metal such as lithium hydroxide or sodium hydroxide may be added for the purpose of suppressing oxygen generation. Thus, by using the electrolytic solution 6 having different potassium component and zinc component contents depending on the charging conditions such as current density and energy density, conduction between the negative electrode 3 and the positive electrode 2 can be reduced.
　亜鉛種の飽和溶解量は、水酸化カリウムの濃度により変わる。最初の電解液６を上述のように作製する場合、酸化亜鉛を飽和溶解量まで溶解させるのは難しく、溶解量は飽和量よりも小さい値にしかならない。水酸化カリウムを増やした場合の亜鉛種の飽和溶解量の増加割合は、水酸化カリウム量の増加割合よりも大きくなる。すなわち、亜鉛種の飽和溶解量は、水酸化カリウム量に対して比例よりも多くなる。そのため、所望の電解液６よりも水酸化カリウム濃度が高い電解液６を作製し、さらに亜鉛種を所望の濃度よりも高い量まで溶かした後、脱イオン水で薄めることで、亜鉛種が飽和溶解量まで解けた電解液６を作製することができる。また、同様の方法で、亜鉛種が飽和溶解量よりも多く溶けた、過飽和の電解液６を作製することができる。過飽和の電解液６は、長期間放置した場合、亜鉛種が析出する。 The saturation dissolution amount of zinc species varies depending on the concentration of potassium hydroxide. When the first electrolytic solution 6 is produced as described above, it is difficult to dissolve zinc oxide to the saturation dissolution amount, and the dissolution amount is only smaller than the saturation amount. The increase rate of the saturated dissolution amount of the zinc species when potassium hydroxide is increased is larger than the increase rate of the potassium hydroxide amount. That is, the saturated dissolution amount of the zinc species is larger than the proportionality with respect to the potassium hydroxide amount. For this reason, an electrolyte solution 6 having a higher potassium hydroxide concentration than the desired electrolyte solution 6 is prepared, and further zinc species are dissolved to an amount higher than the desired concentration, and then diluted with deionized water to saturate the zinc species. The electrolytic solution 6 that has been dissolved up to the dissolved amount can be produced. Moreover, the supersaturated electrolyte solution 6 in which the zinc species is dissolved in a larger amount than the saturated dissolution amount can be produced by the same method. When the supersaturated electrolytic solution 6 is left for a long period of time, zinc species are deposited.
　粉末７は、亜鉛を含む。具体的には、粉末７は、例えば粉末状に加工または生成された酸化亜鉛、水酸化亜鉛等である。粉末７は、アルカリ水溶液中には容易に溶解するが、亜鉛種の飽和した電解液６中には溶解せずに分散または浮遊し、一部が沈降した状態で電解液６中に混在する。電解液６が長時間静置されていた場合、ほとんどの粉末７が、電解液６の中で沈降した状態になることもあるが、電解液６に対流等を生じさせれば、沈降していた粉末７の一部は、電解液６に分散または浮遊した状態になる。つまり、粉末７は、電解液６中に移動可能に存在している。なお、ここで移動可能とは、粉末７が、周囲の他の粉末７の間にできた局所的な空間の中のみを移動できることではなく、電解液６の中を別の位置に粉末７が移動することにより、当初の位置以外の電解液６に粉末７が晒されるようになっていることを表す。さらに、移動可能の範疇には、正極２および負極３の両方の近傍まで粉末７が移動できるようになっていることや、筐体１７内に存在する電解液６中の、ほぼどこにでも粉末７が移動できるようになっていることが含まれる。電解液６中に溶存する亜鉛種である［Ｚｎ（ＯＨ）４］２－が消費されると、電解液６中に混在する粉末７は、粉末７および電解液６が互いに平衡状態を維持するよう電解液６中に溶存する亜鉛種が飽和に近づくように溶解する。 The powder 7 contains zinc. Specifically, the powder 7 is, for example, zinc oxide, zinc hydroxide or the like processed or generated into a powder form. The powder 7 is easily dissolved in the alkaline aqueous solution, but is not dissolved in the zinc-saturated electrolytic solution 6 but is dispersed or floated, and is mixed in the electrolytic solution 6 in a partially settled state. When the electrolytic solution 6 is left standing for a long time, most of the powder 7 may settle in the electrolytic solution 6, but if the electrolytic solution 6 causes convection, the powder 7 is settled. A part of the powder 7 is dispersed or suspended in the electrolytic solution 6. That is, the powder 7 exists so as to be movable in the electrolytic solution 6. Here, the phrase “movable” does not mean that the powder 7 can move only in a local space formed between other surrounding powders 7, but the powder 7 can be moved to another position in the electrolytic solution 6. It represents that the powder 7 is exposed to the electrolyte solution 6 other than the original position by moving. Further, the movable category includes that the powder 7 can move to the vicinity of both the positive electrode 2 and the negative electrode 3, and the powder 7 almost everywhere in the electrolyte 6 existing in the housing 17. It is included that can be moved. When [Zn (OH) 4 ] 2− which is a zinc species dissolved in the electrolytic solution 6 is consumed, the powder 7 mixed in the electrolytic solution 6 maintains an equilibrium state between the powder 7 and the electrolytic solution 6. The zinc species dissolved in the electrolyte solution 6 is dissolved so as to approach saturation.
　気泡８は、例えば正極２、負極３および電解液６に対して不活性な気体で構成される。このような気体としては、例えば、窒素ガス、ヘリウムガス、ネオンガス、またはアルゴンガスなどが挙げられる。電解液６に不活性な気体の気泡８を発生させることにより、電解液６の変性を低減することができる。また、例えば、亜鉛種を含有するアルカリ水溶液である電解液６の劣化を低減し、電解液６のイオン伝導度を高く維持することができる。なお、気体は空気を含有してもよい。 The bubble 8 is composed of a gas inert to the positive electrode 2, the negative electrode 3, and the electrolytic solution 6, for example. Examples of such a gas include nitrogen gas, helium gas, neon gas, and argon gas. By generating inert gas bubbles 8 in the electrolytic solution 6, denaturation of the electrolytic solution 6 can be reduced. Further, for example, it is possible to reduce deterioration of the electrolytic solution 6 that is an alkaline aqueous solution containing zinc species, and to keep the ionic conductivity of the electrolytic solution 6 high. The gas may contain air.
　発生部９から電解液６中に供給された気体により発生した気泡８は、所定の間隔で配置された電極間、より具体的には、負極３ａと正極２との間、正極２と負極３ｂとの間において、それぞれ電解液６中を浮上する。電解液６中を気泡８として浮上した気体は、電解液６の液面６ａで消滅し、上板１８と電解液６の液面６ａとの間に気体層１３を構成する。 The bubbles 8 generated by the gas supplied from the generating unit 9 into the electrolytic solution 6 are between the electrodes arranged at a predetermined interval, more specifically, between the negative electrode 3a and the positive electrode 2, and between the positive electrode 2 and the negative electrode 3b. And float in the electrolytic solution 6 respectively. The gas floating in the electrolytic solution 6 as bubbles 8 disappears at the liquid level 6 a of the electrolytic solution 6, and the gas layer 13 is formed between the upper plate 18 and the liquid level 6 a of the electrolytic solution 6.
　ここで、フロー電池１における電極反応について、正極活物質として水酸化ニッケルを適用したニッケル亜鉛電池を例に挙げて説明する。充電時における正極２および負極３での反応式はそれぞれ、以下のとおりである。 Here, the electrode reaction in the flow battery 1 will be described by taking a nickel zinc battery to which nickel hydroxide is applied as a positive electrode active material as an example. The reaction formulas at the positive electrode 2 and the negative electrode 3 during charging are as follows.
　正極：Ｎｉ（ＯＨ）２　＋　ＯＨ－　→　ＮｉＯＯＨ　＋　Ｈ２Ｏ　＋　ｅ－
　負極：［Ｚｎ（ＯＨ）４］２－　＋　２ｅ－　→　Ｚｎ　＋４ＯＨ－ Positive electrode: Ni (OH) 2 + OH − → NiOOH + H 2 O + e −
Negative electrode: [Zn (OH) 4 ] 2 + 2e − → Zn + 4OH −
　一般的には、この反応に伴って負極３で生成したデンドライトが正極２側へ成長し、正極２と負極３とが導通する懸念がある。反応式から明らかなように、負極３では、充電により亜鉛が析出するのに伴い、負極３の近傍における［Ｚｎ（ＯＨ）４］２－の濃度が低下する。そして、析出した亜鉛の近傍で［Ｚｎ（ＯＨ）４］２－の濃度が低下する現象が、デンドライトとして成長する一因である。すなわち、充電時に消費される電解液６中の［Ｚｎ（ＯＨ）４］２－を補給することにより、電解液６中の亜鉛種である［Ｚｎ（ＯＨ）４］２－の濃度が高い状態に保持される。これにより、デンドライトの成長が低減され、正極２と負極３とが導通する可能性が低減される。 In general, there is a concern that dendrite produced in the negative electrode 3 grows toward the positive electrode 2 with this reaction, and the positive electrode 2 and the negative electrode 3 are electrically connected. As apparent from the reaction formula, in the negative electrode 3, the concentration of [Zn (OH) 4 ] 2− in the vicinity of the negative electrode 3 decreases as zinc is deposited by charging. The phenomenon that the concentration of [Zn (OH) 4 ] 2− decreases in the vicinity of the precipitated zinc is one of the reasons for growing as dendrites. That is, by replenishing [Zn (OH) 4 ] 2− in the electrolytic solution 6 consumed during charging, the concentration of [Zn (OH) 4 ] 2− which is a zinc species in the electrolytic solution 6 is high. Retained. Thereby, the growth of dendrite is reduced, and the possibility that the positive electrode 2 and the negative electrode 3 are electrically connected is reduced.
　放電に伴って負極３から出る亜鉛種は、亜鉛種濃度の高い電解液６に対しても溶けやすい。したがって、放電後の電解液６は、亜鉛種濃度が高く、飽和量に近くなっている。一方、最初に用意する電解液６として、単に酸化亜鉛を溶かしたものを用いると、亜鉛種濃度は、飽和量よりも低く、デンドライトが成長しやすくなる。そのため、フロー電池１に最初に入れる電解液６としては、上述した方法などで作製した、亜鉛種濃度がほぼ飽和したもの、あるいは過飽和となったものを使用するのがよい。 Zinc species coming out of the negative electrode 3 along with the discharge are easily dissolved in the electrolytic solution 6 having a high zinc species concentration. Therefore, the electrolytic solution 6 after discharge has a high zinc species concentration and is close to the saturation amount. On the other hand, when the electrolyte solution 6 prepared first is obtained by simply dissolving zinc oxide, the zinc species concentration is lower than the saturation amount, and dendrites are likely to grow. For this reason, as the electrolytic solution 6 that is initially put in the flow battery 1, it is preferable to use a solution that is produced by the above-described method or the like and that is substantially saturated or supersaturated.
　第１の実施形態に係るフロー電池１では、電解液６中に亜鉛を含む粉末７を混在させるとともに、発生部９の吐出口９ａから電解液６中に気体を供給して気泡８を発生させる。気泡８は、負極３ａと正極２との間、正極２と負極３ｂとの間のそれぞれにおいて筐体１７の下方から上方に向かって電解液６中を浮上する。 In the flow battery 1 according to the first embodiment, the powder 7 containing zinc is mixed in the electrolytic solution 6 and gas is supplied into the electrolytic solution 6 from the discharge port 9a of the generating unit 9 to generate the bubbles 8. . The bubbles 8 float in the electrolytic solution 6 from the lower side of the housing 17 to the upper side between the negative electrode 3a and the positive electrode 2 and between the positive electrode 2 and the negative electrode 3b.
　また、電極間における上記した気泡８の浮上に伴い、電解液６には上昇液流が発生し、負極３ａと正極２との間、正極２と負極３ｂとの間では反応部１０の内底１０ｅ側から上方に向かって電解液６が流動する。そして、電解液６の上昇液流に伴い、主に反応部１０の内壁１０ａと負極３ａとの間、および内壁１０ｂと負極３ｂとの間で下降液流が発生し、電解液６が反応部１０の内部を上方から下方に向かって流動する。 In addition, as the bubbles 8 rise between the electrodes, an upward liquid flow is generated in the electrolyte 6, and the inner bottom of the reaction unit 10 is between the negative electrode 3 a and the positive electrode 2 and between the positive electrode 2 and the negative electrode 3 b. The electrolyte 6 flows upward from the 10e side. Along with the rising liquid flow of the electrolytic solution 6, a descending liquid flow is generated mainly between the inner wall 10a and the negative electrode 3a of the reaction part 10 and between the inner wall 10b and the negative electrode 3b. The inside of 10 flows from top to bottom.
　これにより、充電によって電解液６中の［Ｚｎ（ＯＨ）４］２－が消費されると、これに追従するように粉末７中の亜鉛が溶解することで［Ｚｎ（ＯＨ）４］２－が電解液６中に補給される。このため、電解液６中の［Ｚｎ（ＯＨ）４］２－を濃度が高い状態に保つことができ、デンドライトの成長に伴う正極２と負極３との導通の可能性を低減することができる。 Thus, when [Zn (OH) 4 ] 2− in the electrolytic solution 6 is consumed by charging, the zinc in the powder 7 is dissolved so as to follow this, and [Zn (OH) 4 ] 2− Is replenished in the electrolyte 6. Therefore, [Zn (OH) 4 ] 2− in the electrolytic solution 6 can be kept in a high concentration state, and the possibility of conduction between the positive electrode 2 and the negative electrode 3 accompanying the growth of dendrite can be reduced. .
　なお、粉末７としては、酸化亜鉛および水酸化亜鉛以外に、金属亜鉛、亜鉛酸カルシウム、炭酸亜鉛、硫酸亜鉛、塩化亜鉛などが挙げられ、酸化亜鉛および水酸化亜鉛が好ましい。 The powder 7 includes metal zinc, calcium zincate, zinc carbonate, zinc sulfate, zinc chloride and the like in addition to zinc oxide and zinc hydroxide, and zinc oxide and zinc hydroxide are preferred.
　また、負極３では、放電によりＺｎが消費され、［Ｚｎ（ＯＨ）４］２－を生成するが、電解液６はすでに飽和状態であるため、電解液６中では、過剰となった［Ｚｎ（ＯＨ）４］２－からＺｎＯが析出する。このとき負極３で消費される亜鉛は、充電時に負極３の表面に析出した亜鉛である。このため、元来亜鉛種を含有する負極を用いて充放電を繰り返す場合とは異なり、負極３の表面形状が変化するいわゆるシェイプチェンジが生じない。これにより、第１の実施形態に係るフロー電池１によれば、負極３の経時劣化を低減することができる。なお、電解液６の状態によっては、過剰となった［Ｚｎ（ＯＨ）４］２－から析出するのは、Ｚｎ（ＯＨ）２や、ＺｎＯとＺｎ（ＯＨ）２とが混合したものになる。 In the negative electrode 3, Zn is consumed by discharge to generate [Zn (OH) 4 ] 2− , but the electrolytic solution 6 is already in a saturated state. (OH) 4 ] 2- precipitates ZnO. At this time, the zinc consumed in the negative electrode 3 is zinc deposited on the surface of the negative electrode 3 during charging. For this reason, unlike the case where charge / discharge is repeated using a negative electrode originally containing a zinc species, a so-called shape change in which the surface shape of the negative electrode 3 changes does not occur. Thereby, according to the flow battery 1 which concerns on 1st Embodiment, the time-dependent deterioration of the negative electrode 3 can be reduced. Depending on the state of the electrolytic solution 6, the precipitated [Zn (OH) 4 ] 2− may be Zn (OH) 2 or a mixture of ZnO and Zn (OH) 2. .
　上記したように、負極３では、電解液６中の［Ｚｎ（ＯＨ）４］２－を濃度が高い状態に保つことによりデンドライトの成長が低減される。ただし、充電時に飽和状態または高濃度の［Ｚｎ（ＯＨ）４］２－を含有する電解液６が負極３の近傍に滞留すると、苔状に析出した亜鉛が負極３の表面に付着する場合がある。苔状に析出した亜鉛は、例えば嵩密度が４１２０ｋｇ・ｍ－３程度である平常時に析出した亜鉛と比較して嵩高いため、正極２と負極３との間隔が狭まることで気泡８や電解液６の流れが阻害され、反応部１０内に収容された電解液６が滞留しやすくなる。また、負極３に析出した苔状の亜鉛が正極２にまで到達すると、負極３と正極２とが導通する。 As described above, in the negative electrode 3, dendrite growth is reduced by keeping [Zn (OH) 4 ] 2− in the electrolytic solution 6 in a high concentration state. However, if electrolyte 6 containing saturated or high-concentration [Zn (OH) 4 ] 2− stays in the vicinity of negative electrode 3 during charging, moss-like zinc deposited may adhere to the surface of negative electrode 3. is there. The zinc deposited in the form of moss is bulky as compared with, for example, zinc deposited in a normal state having a bulk density of about 4120 kg · m −3, so that the gap between the positive electrode 2 and the negative electrode 3 is reduced, so that the bubbles 8 and the electrolyte solution 6 is hindered, and the electrolytic solution 6 accommodated in the reaction unit 10 tends to stay. Further, when the mossy zinc deposited on the negative electrode 3 reaches the positive electrode 2, the negative electrode 3 and the positive electrode 2 are electrically connected.
　そこで、反応部１０に収容される電解液６の単位時間当たりの流量に上限を設けるとよい。具体的には、気泡８の発生量、すなわち発生部９から反応部１０の内部に吐出される気体の供給量を１分間当たり２ｄｍ３以下、特に１ｄｍ３以上２ｄｍ３以下とすることができる。このように気泡８の発生量を規定することにより、負極３の表面における樹状または苔状の亜鉛の析出が低減する。このため、負極３と正極２とが導通する不具合が低減する。 Therefore, it is preferable to set an upper limit on the flow rate per unit time of the electrolytic solution 6 accommodated in the reaction unit 10. Specifically, the amount of bubbles 8, that is to say from the generator 9 2 dm per the supply amount of the gas for 1 minute 3 ejected into the reaction section 10 or less, especially 1 dm 3 or more 2 dm 3 or less. By regulating the amount of bubbles 8 generated in this way, the precipitation of dendritic or mossy zinc on the surface of the negative electrode 3 is reduced. For this reason, the malfunction that the negative electrode 3 and the positive electrode 2 conduct | electrically_connect is reduced.
　第１の実施形態に係るフロー電池１についてさらに説明する。発生部９は、反応部１０の下方に配置されている。発生部９は、後述する供給部１４から供給された気体を一時的に貯留するよう内部が中空となっている。また、反応部１０の内底１０ｅは、発生部９の中空部分を覆うように配置されており、発生部９の天板を兼ねている。 The flow battery 1 according to the first embodiment will be further described. The generation unit 9 is disposed below the reaction unit 10. The generating unit 9 is hollow so as to temporarily store a gas supplied from a supply unit 14 to be described later. In addition, the inner bottom 10 e of the reaction unit 10 is disposed so as to cover the hollow portion of the generation unit 9, and also serves as a top plate of the generation unit 9.
　また、内底１０ｅは、Ｘ軸方向およびＹ軸方向に沿って並ぶ複数の吐出口９ａを有している。発生部９は、供給部１４から供給された気体を吐出口９ａから吐出することにより、電解液６中に気泡８を発生させる。吐出口９ａは、例えば０．０５ｍｍ以上０．５ｍｍ以下の直径を有する。吐出口９ａの直径をこのように規定することにより、吐出口９ａから発生部９の内部の中空部分に電解液６や粉末７が進入する不具合を低減することができる。また、吐出口９ａから吐出される気体に対し、気泡８を発生させるのに適した圧力損失を与えることができる。 The inner bottom 10e has a plurality of discharge ports 9a arranged along the X-axis direction and the Y-axis direction. The generating unit 9 generates bubbles 8 in the electrolytic solution 6 by discharging the gas supplied from the supplying unit 14 from the discharge port 9a. The discharge port 9a has a diameter of 0.05 mm or more and 0.5 mm or less, for example. By defining the diameter of the discharge port 9a in this way, it is possible to reduce the problem that the electrolytic solution 6 and the powder 7 enter the hollow portion inside the generating unit 9 from the discharge port 9a. Further, it is possible to give a pressure loss suitable for generating the bubbles 8 to the gas discharged from the discharge port 9a.
　また、吐出口９ａのＸ軸方向に沿った間隔（ピッチ）は、例えば、２．５ｍｍ以上５０ｍｍ以下であり、さらに１０ｍｍ以下にしてもよい。ただし、吐出口９ａは、発生した気泡８を互いに向かい合う正極２と負極３との間にそれぞれ適切に流動させることができるように配置されるものであれば、大きさや間隔に制限はない。 Further, the interval (pitch) along the X-axis direction of the discharge ports 9a is, for example, 2.5 mm or more and 50 mm or less, and may be 10 mm or less. However, the discharge port 9a is not limited in size and interval as long as the generated bubbles 8 can be appropriately flowed between the positive electrode 2 and the negative electrode 3 facing each other.
　筐体１７および上板１８は、例えば、ポリスチレン、ポリプロピレン、ポリエチレンテレフタレート、ポリテトラフルオロエチレン、ポリ塩化ビニルなど、耐アルカリ性および絶縁性を有する樹脂材料で構成される。筐体１７および上板１８は、好ましくは互いに同じ材料で構成されるが、異なる材料で構成されてもよい。また、発生部９は、反応部１０の内部に配置されてもよい。 The housing 17 and the upper plate 18 are made of a resin material having alkali resistance and insulation, such as polystyrene, polypropylene, polyethylene terephthalate, polytetrafluoroethylene, polyvinyl chloride, and the like. The housing 17 and the upper plate 18 are preferably made of the same material, but may be made of different materials. The generation unit 9 may be disposed inside the reaction unit 10.
　供給部１４は、配管１６を介して筐体１７の内部から回収された気体を、配管１５を介して発生部９に供給する。供給部１４は、例えば気体を移送可能なポンプ（気体ポンプ）、コンプレッサまたはブロワである。供給部１４の気密性を高くすれば、気体や電解液６に由来する水蒸気を外部に漏出させることによるフロー電池１の発電性能の低下が起きにくい。 The supply unit 14 supplies the gas collected from the inside of the housing 17 through the pipe 16 to the generation unit 9 through the pipe 15. The supply unit 14 is, for example, a pump (gas pump), a compressor, or a blower that can transfer gas. If the airtightness of the supply unit 14 is increased, the power generation performance of the flow battery 1 is less likely to decrease due to leakage of gas or water vapor derived from the electrolyte 6 to the outside.
　次に、フロー電池１における電極間の接続について説明する。図２は、第１の実施形態に係るフロー電池１の電極間の接続の一例について説明する図である。 Next, the connection between the electrodes in the flow battery 1 will be described. FIG. 2 is a diagram illustrating an example of connection between electrodes of the flow battery 1 according to the first embodiment.
　図２に示すように、負極３ａおよび負極３ｂは並列接続されている。このように負極３を並列に接続することにより、正極２および負極３の総数が異なる場合であってもフロー電池１の各電極間を適切に接続し、使用することができる。 As shown in FIG. 2, the negative electrode 3a and the negative electrode 3b are connected in parallel. By connecting the negative electrodes 3 in parallel as described above, the electrodes of the flow battery 1 can be appropriately connected and used even when the total number of the positive electrodes 2 and the negative electrodes 3 is different.
　また、第１の実施形態に係るフロー電池１では、正極２を挟んで互いに向かい合うように配置された負極３ａ，３ｂを備える。このように１つの正極２に対して２つの負極３ａ，３ｂが対応したフロー電池１では、正極２と負極３とが１：１で対応するフロー電池と比較して負極１つ当たりの電流密度が低下する。このため、第１の実施形態に係るフロー電池１によれば、負極３ａ，３ｂでのデンドライトの生成がさらに低減されるため、負極３ａ，３ｂと正極２との導通をさらに低減することができる。 Further, the flow battery 1 according to the first embodiment includes the negative electrodes 3a and 3b arranged so as to face each other with the positive electrode 2 interposed therebetween. Thus, in the flow battery 1 in which the two negative electrodes 3a and 3b correspond to one positive electrode 2, the current density per negative electrode is compared with the flow battery in which the positive electrode 2 and the negative electrode 3 correspond 1: 1. Decreases. For this reason, according to the flow battery 1 which concerns on 1st Embodiment, since the production | generation of the dendrite in the negative electrodes 3a and 3b is further reduced, conduction | electrical_connection with the negative electrodes 3a and 3b and the positive electrode 2 can further be reduced. .
　なお、図１に示すフロー電池１では、合計３枚の電極が、負極３および正極２が交互に配置されるように構成されたが、これに限らず、正極２および負極３をそれぞれ１枚ずつ配置させてもよい。また、図１に示すフロー電池１では、両端がともに負極３となるように構成されたが、これに限らず、両端がともに正極２となるように構成してもよい。 In the flow battery 1 shown in FIG. 1, the total of three electrodes are configured such that the negative electrodes 3 and the positive electrodes 2 are alternately arranged. However, the present invention is not limited to this, and one positive electrode 2 and one negative electrode 3 are provided. You may arrange them one by one. Further, in the flow battery 1 shown in FIG. 1, both ends are configured to be the negative electrode 3, but the present invention is not limited thereto, and both ends may be configured to be the positive electrode 2.
＜第２の実施形態＞
　図３は、第２の実施形態に係るフロー電池の概略を示す図である。図３に示すフロー電池１Ａは、正極２および負極３の数および吐出口９ａの配置が異なることを除き、第１の実施形態に係るフロー電池１と同様の構成を有している。 <Second Embodiment>
FIG. 3 is a diagram schematically illustrating the flow battery according to the second embodiment. A flow battery 1A shown in FIG. 3 has the same configuration as the flow battery 1 according to the first embodiment except that the number of positive electrodes 2 and negative electrodes 3 and the arrangement of the discharge ports 9a are different.
　正極２は、正極２Ａ，２Ｂを含む。負極３は、負極３Ａ，３Ｂおよび３Ｃを含む。正極２および負極３は、負極３Ａと、正極２Ａと、負極３Ｂと、正極２Ｂと、負極３Ｃとが予め定められた間隔でＹ軸方向に沿って順に並ぶように配置されている。そして、吐出口９ａは、隣り合う正極２と負極３との間、すなわち負極３Ａと正極２Ａとの間、正極２Ａと負極３Ｂとの間、負極３Ｂと正極２Ｂとの間、正極２Ｂと負極３Ｃとの間の電解液６中を気泡８が適切に浮上するように配置される。 The positive electrode 2 includes positive electrodes 2A and 2B. The negative electrode 3 includes negative electrodes 3A, 3B and 3C. The positive electrode 2 and the negative electrode 3 are arranged so that the negative electrode 3A, the positive electrode 2A, the negative electrode 3B, the positive electrode 2B, and the negative electrode 3C are arranged in order along the Y-axis direction at predetermined intervals. The discharge port 9a is located between the adjacent positive electrode 2 and the negative electrode 3, that is, between the negative electrode 3A and the positive electrode 2A, between the positive electrode 2A and the negative electrode 3B, between the negative electrode 3B and the positive electrode 2B, and between the positive electrode 2B and the negative electrode. It arrange | positions so that the bubble 8 may float appropriately in the electrolyte solution 6 between 3C.
　図４は、第２の実施形態に係るフロー電池１Ａの電極間の接続の一例について説明する図である。図４に示すように、正極２Ａ，２Ｂは並列接続されている。また、負極３Ａ，３Ｂおよび３Ｃは並列接続されている。このように正極２および負極３をそれぞれ並列に接続することにより、フロー電池１Ａの各電極間を適切に接続し、使用することができる。 FIG. 4 is a diagram for explaining an example of connection between electrodes of the flow battery 1A according to the second embodiment. As shown in FIG. 4, the positive electrodes 2A and 2B are connected in parallel. The negative electrodes 3A, 3B, and 3C are connected in parallel. Thus, by connecting the positive electrode 2 and the negative electrode 3 in parallel, the electrodes of the flow battery 1A can be appropriately connected and used.
　第２の実施形態に係るフロー電池１Ａでは、１つの反応部１０に対し、合計５枚の電極が収容されており、第１の実施形態に係るフロー電池１と比較してエネルギー密度を高めることができる。このため、フロー電池１Ａにおいては、エネルギー密度に応じた電解液６を使用することができる。ここで、電解液６としては、例えば、電流密度が２２５Ａ・ｍ－２、エネルギー密度が６０Ｗｈ・ｄｍ－３となる条件下において、１ｄｍ３当たり１５．５ｍｏｌ以上のカリウム成分と３．２ｍｏｌ以上の亜鉛成分とを含有するアルカリ水溶液を使用することができる。このようにエネルギー密度に応じて亜鉛成分の含有量を規定した電解液６を使用することにより、充電時の負極３における樹状および苔状の亜鉛析出が低減する。このため、第２の実施形態に係るフロー電池１Ａによれば、負極３と正極２との導通を低減することができる。 In the flow battery 1A according to the second embodiment, a total of five electrodes are accommodated in one reaction unit 10, and the energy density is increased as compared with the flow battery 1 according to the first embodiment. Can do. For this reason, in the flow battery 1A, the electrolyte solution 6 according to the energy density can be used. Here, as the electrolytic solution 6, for example, under the condition that the current density is 225 A · m −2 and the energy density is 60 Wh · dm −3 , 15.5 mol or more potassium component and 3.2 mol or more per dm 3 are used. An alkaline aqueous solution containing a zinc component can be used. By using the electrolytic solution 6 in which the content of the zinc component is regulated according to the energy density in this way, dendritic and mossy zinc deposition on the negative electrode 3 during charging is reduced. For this reason, according to 1 A of flow batteries which concern on 2nd Embodiment, conduction | electrical_connection with the negative electrode 3 and the positive electrode 2 can be reduced.
　なお、上記した実施形態では、合計５枚の電極が負極３および正極２が交互に配置されるように構成されたが、これに限らず、６枚以上の電極を交互に配置するようにしてもよい。また、上記した各実施形態では、両端がともに負極３となるように構成されたが、一方を正極２、他方を負極３となるように同枚数の負極３および正極２をそれぞれ交互に配置してもよい。 In the above-described embodiment, a total of five electrodes are configured such that the negative electrode 3 and the positive electrode 2 are alternately arranged. However, the present invention is not limited thereto, and six or more electrodes are alternately arranged. Also good. In each of the above-described embodiments, both ends are configured to be the negative electrode 3, but the same number of the negative electrodes 3 and the positive electrodes 2 are alternately arranged so that one is the positive electrode 2 and the other is the negative electrode 3. May be.
＜第３の実施形態＞
　図５は、第３の実施形態に係るフロー電池の概略を示す図である。図５に示すフロー電池１Ｂは、図１に示す発生部９、供給部１４、配管１５，１６、に代えて、供給部１４ａ、配管１５ａ，１６ａを備えることを除き、第１の実施形態に係るフロー電池１と同様の構成を有している。 <Third Embodiment>
FIG. 5 is a diagram schematically illustrating a flow battery according to the third embodiment. The flow battery 1B shown in FIG. 5 is the same as that of the first embodiment except that the generator 9, the supply unit 14, and the pipes 15 and 16 shown in FIG. 1 are replaced with a supply part 14 a and pipes 15 a and 16 a. The flow battery 1 has the same configuration.
　供給部１４ａは、配管１６ａを介して筐体１７の内部から回収された、粉末７が混在する電解液６を、配管１５ａを介して筐体１７の下部に供給する。供給部１４ａは、流動装置の一例である。 The supply unit 14a supplies the electrolytic solution 6 mixed with the powder 7 collected from the inside of the casing 17 through the pipe 16a to the lower part of the casing 17 through the pipe 15a. The supply unit 14a is an example of a flow device.
　供給部１４ａは、例えば電解液６を移送可能なポンプである。供給部１４ａの気密性を高くすれば、粉末７および電解液６を外部に漏出させることによるフロー電池１Ｂの発電性能の低下が起きにくい。そして、筐体１７の内部に送られた電解液６は、第１の実施形態に係るフロー電池１と同様に、各電極間を上方に流動する間に充放電反応に供されることとなる。 The supply unit 14a is, for example, a pump capable of transferring the electrolytic solution 6. If the airtightness of the supply unit 14a is increased, the power generation performance of the flow battery 1B is less likely to decrease due to leakage of the powder 7 and the electrolyte 6 to the outside. And the electrolyte solution 6 sent to the inside of the housing | casing 17 will be used for charging / discharging reaction, while flowing upward between each electrode similarly to the flow battery 1 which concerns on 1st Embodiment. .
　このように発生部９を有しないフロー電池１Ｂにおいても、電解液６中のカリウム成分および亜鉛成分の含有量を調整することにより、負極３と正極２との導通を低減することができる。 Thus, even in the flow battery 1B that does not have the generation unit 9, the conduction between the negative electrode 3 and the positive electrode 2 can be reduced by adjusting the content of the potassium component and the zinc component in the electrolytic solution 6.
　なお、図５に示すフロー電池１Ｂでは、配管１６ａに接続された開口が、各電極の主面と向かい合う内壁１０ｂ、すなわち反応部１０のＹ軸方向側の端部に設けられているが、これに限らず、Ｘ軸方向側の端部に設けられてもよい。 In the flow battery 1B shown in FIG. 5, the opening connected to the pipe 16a is provided on the inner wall 10b facing the main surface of each electrode, that is, the end of the reaction unit 10 on the Y axis direction side. However, the present invention may be provided at the end on the X axis direction side.
　また、図５に示すフロー電池１Ｂでは、供給部１４ａは、粉末７が混在する電解液６を筐体１７に供給するとしたが、これに限らず、電解液６のみを供給することとしてもよい。かかる場合、例えば配管１６ａの途中に、粉末７が混在する電解液６を一時的に貯留するタンクを設け、タンク内部において電解液６中に溶解する［Ｚｎ（ＯＨ）４］２－の濃度を調整することとしてもよい。 Further, in the flow battery 1B shown in FIG. 5, the supply unit 14a supplies the electrolytic solution 6 in which the powder 7 is mixed to the casing 17, but the supply unit 14a is not limited to this and may supply only the electrolytic solution 6. . In such a case, for example, a tank for temporarily storing the electrolytic solution 6 in which the powder 7 is mixed is provided in the middle of the pipe 16a, and the concentration of [Zn (OH) 4 ] 2− dissolved in the electrolytic solution 6 is set inside the tank. It is good also as adjusting.
　以上、本発明の実施形態について説明したが、本発明は上記実施形態に限定されるものではなく、その趣旨を逸脱しない限りにおいて種々の変更が可能である。例えば、図５に示すフロー電池１Ｂが有する正極２および負極３に代えて、図３に示すフロー電池１Ａが有する正極２および負極３を配置させてもよい。 As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the meaning. For example, instead of the positive electrode 2 and the negative electrode 3 included in the flow battery 1B illustrated in FIG. 5, the positive electrode 2 and the negative electrode 3 included in the flow battery 1A illustrated in FIG. 3 may be disposed.
　また、上記した各実施形態では、電解液６中に粉末７が混在されているとして説明したが、これに限らず、粉末７を有しなくてもよい。このとき、電解液６中に溶存する亜鉛成分は、飽和状態であってもよく、飽和状態よりも低い濃度であってもよい。さらに、電解液６は、過飽和状態となるように亜鉛成分を溶存させたものであってもよい。また、高濃度の［Ｚｎ（ＯＨ）４］２－を含有する電解液６を正極２と負極３との間に速やかに供給する観点から、正極２および負極３の上端が、電解液６の液面６ａよりも下方に配置されるように電解液６の量を調整してもよい。 In each of the above-described embodiments, the powder 7 is described as being mixed in the electrolytic solution 6. At this time, the zinc component dissolved in the electrolytic solution 6 may be in a saturated state or a concentration lower than that in the saturated state. Furthermore, the electrolyte solution 6 may be one in which a zinc component is dissolved so as to be in a supersaturated state. Further, from the viewpoint of quickly supplying the electrolytic solution 6 containing a high concentration of [Zn (OH) 4 ] 2− between the positive electrode 2 and the negative electrode 3, the upper ends of the positive electrode 2 and the negative electrode 3 are connected to the electrolytic solution 6. You may adjust the quantity of the electrolyte solution 6 so that it may be arrange | positioned below the liquid level 6a.
　また、上記した各実施形態では、隔膜４，５は正極２の厚み方向の両側を挟むように配置されるとして説明したが、これに限らず、正極２と負極３との間に配置されていればよく、また、正極２を被覆していてもよい。 Further, in each of the above embodiments, the diaphragms 4 and 5 have been described as being disposed so as to sandwich both sides in the thickness direction of the positive electrode 2, but the present invention is not limited thereto, and is disposed between the positive electrode 2 and the negative electrode 3. And the positive electrode 2 may be covered.
　なお、供給部１４，１４ａは、常時動作させてもよいが、電力消費を低減する観点から、放電時には充電時よりも気体または電解液６の供給レートを低下させてもよい。 In addition, although the supply parts 14 and 14a may be always operated, from the viewpoint of reducing power consumption, the supply rate of the gas or the electrolyte solution 6 may be lowered during discharging than during charging.
　以下、上記した第２の実施形態に係るフロー電池１Ａを作製し、充電により負極３の表面に付着する亜鉛の堆積の様子を評価した。図６は、充電により負極に付着する亜鉛を評価した結果を示す図である。 Hereinafter, the flow battery 1A according to the second embodiment described above was manufactured, and the state of deposition of zinc attached to the surface of the negative electrode 3 by charging was evaluated. FIG. 6 is a diagram showing the result of evaluating zinc adhering to the negative electrode by charging.
　図６に示すように、試料Ｎｏ．１～１０では、電解液６として、脱イオン水中に含まれる水酸化カリウム（ＫＯＨ）およびＺｎイオン（［Ｚｎ（ＯＨ）４］２－）の濃度を変更させたものをそれぞれ使用した。試料Ｎｏ．９、１０では、電解液６に溶解しない亜鉛成分が残り、図６に示したイオン濃度の電解液６は作製できなかった。また、試料Ｎｏ．３、６では、粉末７として１ｄｍ３の電解液６に対し、１．８ｍｏｌの割合でＺｎＯをさらに添加した。 As shown in FIG. In Nos. 1 to 10, electrolytes 6 having different concentrations of potassium hydroxide (KOH) and Zn ions ([Zn (OH) 4 ] 2− ) contained in deionized water were used. Sample No. In 9, 10, the zinc component which does not melt | dissolve in the electrolyte solution 6 remains, and the electrolyte solution 6 having the ion concentration shown in FIG. Sample No. 3 and 6, ZnO was further added at a rate of 1.8 mol with respect to 1 dm 3 of the electrolyte 6 as the powder 7.
　さらに、気泡８の発生量を２ｄｍ３・ｍｉｎ－１とし、電流密度が２２５ｍＡ・ｍ－２、エネルギー密度が６０Ｗｈ・ｄｍ－３となる条件下で、電池容量が１００％となるまで試料Ｎｏ．１～８のフロー電池１Ａをそれぞれ充電させた後、負極３の表面に析出した亜鉛を評価した。なお、試料Ｎｏ．９、１０のフロー電池１Ａでは、充電前の電解液６中に溶解しない亜鉛成分が残ったため、評価しなかった。 Further, under conditions where the amount of bubbles 8 generated is 2 dm 3 · min −1 , the current density is 225 mA · m −2 , and the energy density is 60 Wh · dm −3 , the sample No. 2 is obtained until the battery capacity reaches 100%. After charging 1 to 8 flow batteries 1A, zinc deposited on the surface of the negative electrode 3 was evaluated. Sample No. In the flow batteries 1A of 9 and 10, since the zinc component which did not melt | dissolve remained in the electrolyte solution 6 before charge, it did not evaluate.
　また、図６においては、負極３の表面にデンドライトが観察されず、特に良好なものを◎とし、目視ではデンドライトは観察されないが、ＳＥＭ（Scanning　Electron　Microscope）または光学顕微鏡で１００倍に拡大するとデンドライトが観察されたものを○、目視でデンドライトが観察されたが、正極には到達していないものを△、成長したデンドライトの一部が正極２に到達しているものを×として４段階で評価した。上記した４段階評価のうち、◎、○および△を、フロー電池１Ａとしての規準を満たしている評価とする。 In FIG. 6, dendrite is not observed on the surface of the negative electrode 3, and particularly good ones are marked with ◎, and dendrite is not visually observed, but when dendritic is magnified 100 times with an SEM (Scanning Electron Microscope) or an optical microscope. Evaluation was made on a four-point scale, with ◯ being observed, dendrite visually observed, △ when not reaching the positive electrode, and x when some of the grown dendrite had reached the positive electrode 2 did. Among the above four-stage evaluations, ◎, ○, and Δ are evaluations that satisfy the criteria for the flow battery 1A.
　また、デンドライトが確認されたものについては、４段階の上記した評価とともに具体的な析出形態について（デンドライト）のように併記した。 In addition, for those in which dendrite was confirmed, a specific precipitation form was also written as (Dendrite) together with the above-described four-stage evaluation.
　図６に示すように、第２の実施形態に係るフロー電池１Ａによれば、カリウム成分としてのＫＯＨおよび亜鉛成分としての［Ｚｎ（ＯＨ）４］２－をそれぞれ所定量含有する電解液６を使用することにより、負極３と正極２との導通の可能性を低減することができる。 As shown in FIG. 6, according to the flow battery 1A according to the second embodiment, the electrolytic solution 6 containing a predetermined amount of KOH as a potassium component and [Zn (OH) 4 ] 2− as a zinc component, respectively. By using it, the possibility of conduction between the negative electrode 3 and the positive electrode 2 can be reduced.
　さらなる効果や変形例は、当業者によって容易に導き出すことができる。このため、本発明のより広範な態様は、以上のように表しかつ記述した特定の詳細および代表的な実施形態に限定されるものではない。したがって、添付の請求の範囲およびその均等物によって定義される総括的な発明の概念の精神または範囲から逸脱することなく、様々な変更が可能である。 Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
　　１，１Ａ，１Ｂ　フロー電池
　　２，２Ａ，２Ｂ　正極
　　３，３ａ，３ｂ，３Ａ，３Ｂ，３Ｃ　負極
　　４，５　隔膜
　　６　電解液
　　７　粉末
　　８　気泡
　　９　発生部
　　９ａ　吐出口
　１０　反応部
　１４，１４ａ　供給部
　１７　筐体
　１８　上板 1, 1A, 1B Flow battery 2, 2A, 2B Positive electrode 3, 3a, 3b, 3A, 3B, 3C Negative electrode 4, 5 Separator 6 Electrolyte 7 Powder 8 Bubble 9 Generation part 9a Discharge port 10 Reaction part 14, 14a Supply part 17 Housing 18 Upper plate

Claims (7)

  1. 　正極および負極と、
    　前記正極および前記負極に接触する電解液と、
    　前記電解液を流動させる流動装置と
    　を備え、
    　前記電解液は、１ｄｍ３当たり８ｍｏｌ以上のカリウム成分と１．３ｍｏｌ以上の亜鉛成分とを含有するアルカリ水溶液であることを特徴とするフロー電池。     A positive electrode and a negative electrode;
    An electrolyte solution in contact with the positive electrode and the negative electrode;
    A flow device for flowing the electrolyte solution,
    The flow battery characterized in that the electrolytic solution is an alkaline aqueous solution containing 8 mol or more of a potassium component and 1.3 mol or more of a zinc component per dm 3 .
  2. 　正極および負極と、
    　前記正極および前記負極に接触する電解液と、
    　前記電解液を流動させる流動装置と
    　を備え、
    　前記電解液は、１ｄｍ３当たり１３．９ｍｏｌ以上のカリウム成分と２．２ｍｏｌ以上の亜鉛成分とを含有するアルカリ水溶液であることを特徴とするフロー電池。     A positive electrode and a negative electrode;
    An electrolyte solution in contact with the positive electrode and the negative electrode;
    A flow device for flowing the electrolyte solution,
    The flow battery according to claim 1, wherein the electrolytic solution is an alkaline aqueous solution containing 13.9 mol or more of a potassium component and 2.2 mol or more of a zinc component per dm 3 .
  3. 　正極および負極と、
    　前記正極および前記負極に接触する電解液と、
    　前記電解液を流動させる流動装置と
    　を備え、
    　前記電解液は、１ｄｍ３当たり１５．５ｍｏｌ以上のカリウム成分と３．２ｍｏｌ以上の亜鉛成分とを含有するアルカリ水溶液であることを特徴とするフロー電池。     A positive electrode and a negative electrode;
    An electrolyte solution in contact with the positive electrode and the negative electrode;
    A flow device for flowing the electrolyte solution,
    The flow battery characterized in that the electrolytic solution is an alkaline aqueous solution containing 15.5 mol or more of a potassium component and 3.2 mol or more of a zinc component per dm 3 .
  4. 　前記流動装置は、前記電解液中に気泡を発生させる発生部を含み、
    　前記気泡は、前記正極と前記負極との間を浮上することを特徴とする請求項１～３のいずれか１つに記載のフロー電池。     The flow device includes a generator that generates bubbles in the electrolytic solution,
    The flow battery according to any one of claims 1 to 3, wherein the bubbles float between the positive electrode and the negative electrode.
  5. 　前記負極は、前記正極を挟んで向かい合う第１負極および第２負極を含むことを特徴とする請求項１～４のいずれか１つに記載のフロー電池。 The flow battery according to any one of claims 1 to 4, wherein the negative electrode includes a first negative electrode and a second negative electrode facing each other with the positive electrode interposed therebetween.
  6. 　亜鉛を含み、前記電解液中を移動可能に混在する粉末をさらに備えることを特徴とする請求項１～５のいずれか１つに記載のフロー電池。 The flow battery according to any one of claims 1 to 5, further comprising a powder containing zinc and movably mixed in the electrolytic solution.
  7. 　前記正極および前記負極の上端は、前記電解液の液面よりも下方に配置されることを特徴とする請求項１～６のいずれか１つに記載のフロー電池。 The flow battery according to any one of claims 1 to 6, wherein upper ends of the positive electrode and the negative electrode are disposed below a liquid surface of the electrolytic solution.
PCT/JP2019/003516 2018-01-31 2019-01-31 Flow battery WO2019151454A1 (en)

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