JP2020021565A - Flow battery - Google Patents

Abstract

To provide a flow battery that can reduce performance degradation.SOLUTION: A flow battery includes an electrode 2, a negative electrode 3, an electrolytic solution 6, and a generating unit 9. The electrolytic solution contacts the positive and negative electrodes. The generating unit has a groove 11 and a discharge port 9a, and is arranged below the positive and negative electrodes. The groove extends in the width direction of the negative electrode. The discharge port discharges gas into the electrolytic solution from the bottom surface of the groove to generate bubbles.SELECTED DRAWING: Figure 1

Description

  The disclosed embodiments relate to a flow battery.

2. Description of the Related Art Conventionally, there is known a flow battery in which an electrolytic solution containing tetrahydroxyzinc acid ion ([Zn (OH) ₄ ] ²⁻ ) is circulated between a positive electrode and a negative electrode (for example, see Non-Patent Document 1). .

  Further, a technique has been proposed in which a negative electrode containing an active material such as a zinc species is covered with an ion conductive layer having selective ion conductivity to suppress the growth of dendrites (for example, see Patent Document 1).

JP-A-2005-185259

Y. Ito. Et al .: Zinc morphology in zinc-nickel flow assisted batteries and impact on performance, Journal of Power Sources, Vol. 196, pp. 2340-2345, 2011

  However, in the battery described above, there is a concern that the active material generated on the electrode surface falls off in a state not contributing to charge and discharge and stays there, thereby deteriorating the battery performance.

  An aspect of the embodiment has been made in view of the above, and has as its object to provide a flow battery that can reduce performance deterioration.

  A flow battery according to one aspect of an embodiment includes a positive electrode, a negative electrode, an electrolyte, and a generator. The electrolyte contacts the positive electrode and the negative electrode. The generator has a groove and a discharge port, and is arranged below the positive electrode and the negative electrode. The groove extends in the width direction of the negative electrode. The discharge port discharges gas into the electrolytic solution from the bottom surface of the groove to generate bubbles.

  According to the flow battery of one embodiment of the present invention, performance deterioration can be reduced.

FIG. 1 is a diagram schematically illustrating a flow battery according to an embodiment. FIG. 2 is a diagram schematically illustrating a top plate included in the flow battery according to the embodiment. FIG. 3 is a sectional view taken along line II of FIG. FIG. 4 is a sectional view taken along line II-II of FIG. FIG. 5 is a diagram illustrating an example of a connection between electrodes of the flow battery according to the embodiment. FIG. 6 is a diagram schematically illustrating a configuration of a top plate included in a flow battery according to a first modification of the embodiment. FIG. 7 is a diagram schematically illustrating a configuration of a top plate included in a flow battery according to a second modification of the embodiment. FIG. 8 is a diagram schematically illustrating a configuration of a top plate included in a flow battery according to a third modification of the embodiment. FIG. 9 is a diagram schematically illustrating a configuration of a top plate included in a flow battery according to a fourth modification of the embodiment. FIG. 10 is a cross-sectional view schematically illustrating a configuration of a top plate included in a flow battery according to a fifth modified example of the embodiment. FIG. 11 is a cross-sectional view schematically illustrating a configuration of a top plate included in a flow battery according to a fifth modified example of the embodiment.

  Hereinafter, embodiments of the flow battery disclosed in the present application will be described in detail with reference to the accompanying drawings. The present invention is not limited by the embodiments described below.

<Flow battery according to embodiment>
FIG. 1 is a diagram schematically illustrating a flow battery according to an 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 section 10 includes the positive electrode 2, the negative electrode 3, the diaphragms 4 and 5, the electrolyte 6, and the powder 7. The flow battery 1 is a device that causes the bubbles 8 generated in the generating unit 9 to float in the electrolytic solution 6 to flow the electrolytic solution 6 contained in the reaction unit 10.

  In order to make the description easy to understand, FIG. 1 illustrates a three-dimensional orthogonal coordinate system including a Z-axis having a vertically upward direction as a positive direction and a vertically downward direction as a negative direction. Such an orthogonal coordinate system may 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. As the nickel compound, for example, nickel oxyhydroxide, nickel hydroxide, nickel hydroxide containing a cobalt compound and the like can be used. As the manganese compound, for example, manganese dioxide or the like can be used. As the cobalt compound, for example, cobalt hydroxide, cobalt oxyhydroxide and the like can be used. Further, the positive electrode 2 may include graphite, carbon black, a conductive resin, or the like. From the viewpoint of the oxidation-reduction potential at which the electrolytic solution 6 is decomposed, the positive electrode 2 may contain a nickel compound. The positive electrode 2 may be made of nickel metal, cobalt metal, manganese metal, or an alloy thereof.

  The positive electrode 2 includes, for example, the above-described positive electrode active material, the conductor, and other additives as a plurality of particles. Specifically, for example, the positive electrode 2 is made of a paste-like positive electrode material containing a particulate active material and a conductor mixed at a predetermined ratio together with a binder that contributes to shape retention, and is made of a conductive material such as foamed nickel. It can be used by press-fitting it into a foamed metal having properties, forming it into a desired shape, and drying it.

  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 material obtained by plating the surface of a stainless steel or copper plate with nickel, tin, or zinc can be used. Alternatively, a partially oxidized surface of the plated surface may be used as the negative electrode 3.

  The negative electrode 3 includes a negative electrode 3a and a negative electrode 3b arranged so as to face each other with the positive electrode 2 interposed therebetween. The positive electrode 2 and the negative electrode 3 are arranged such that the negative electrode 3a, the positive electrode 2, and the negative electrode 3b are sequentially arranged at predetermined intervals along the Y-axis direction. By providing the intervals between the adjacent positive electrode 2 and negative electrode 3 in this manner, a flow path of the electrolytic solution 6 and the bubble 8 between the positive electrode 2 and the negative electrode 3 is secured. When the negative electrode 3a and the negative electrode 3b are described without distinction, they may be simply described as the negative electrode 3 regardless of the drawings.

  The diaphragms 4 and 5 are arranged so as to sandwich both sides of the positive electrode 2 in the thickness direction, that is, the Y-axis direction. The diaphragms 4 and 5 are made of a material that allows movement of ions contained in the electrolyte 6. Specifically, examples of the material of the diaphragms 4 and 5 include an anion conductive material so that the diaphragms 4 and 5 have hydroxide ion conductivity. Examples of the anion conductive material include a gel anion conductive material having a three-dimensional structure such as an organic hydrogel, and a solid polymer type anion conductive material. The solid polymer type anion conductive material is, for example, an oxide, a hydroxide, or a layered double hydroxide containing a polymer and at least one element selected from Groups 1 to 17 of the periodic table. And at least one compound selected from the group consisting of sulfuric acid compounds and phosphoric acid compounds.

The diaphragms 4 and 5 are preferably made of a dense material so as to suppress the permeation of a metal ion complex such as [Zn (OH) ₄ ] ^2- having an ionic radius larger than the hydroxide ion, and It has a predetermined thickness. Examples of the dense material include a material having a relative density of 90% or more, more preferably 92% or more, and still more preferably 95% or more, calculated by the Archimedes method. The predetermined thickness is, for example, 10 μm to 1000 μm, and more preferably 50 μm to 500 μm.

  In this case, it is possible to reduce the possibility that zinc deposited on the negative electrodes 3 a and 3 b 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.

The electrolytic solution 6 is an alkaline aqueous solution containing 6 mol · dm ⁻³ or more of an alkali metal. The alkali metal is, for example, potassium. Specifically, for example, an aqueous solution of potassium hydroxide of 6 to 6.7 moldm- ³ can be used as the electrolyte 6. Further, an alkali metal such as lithium or sodium may be added as a hydroxide (lithium hydroxide, sodium hydroxide) for the purpose of suppressing oxygen generation.

Further, the electrolytic solution 6 contains a zinc component. The zinc component is dissolved in the electrolytic solution 6 as [Zn (OH) ₄ ] ²⁻ . As the zinc component, for example, zinc oxide or zinc hydroxide can be used. Further, the electrolytic solution 6 can be prepared by adding ZnO to a 1 dm ⁻³ aqueous solution of potassium hydroxide at a ratio of 0.5 mol, and adding a powder 7 described below as necessary. The electrolyte solution 6 not used or after the discharge is completed is, for example, 1 × 10 ⁻⁴ mol · dm ⁻³ or more and 5 × 10 ⁻² mol · dm ⁻³ or less, preferably 1 × 10 ⁻³ mol · dm ⁻³ or more. A zinc component of 2.5 × 10 ⁻² mol · dm ⁻³ or less can be contained.

Powder 7 contains zinc. Specifically, the powder 7 is, for example, zinc oxide, zinc hydroxide, or the like processed or generated into a powder. The powder 7 is easily dissolved in the alkaline aqueous solution, but is dispersed or suspended without dissolving in the electrolytic solution 6 saturated with the zinc species, and is mixed in the electrolytic solution 6 in a partially settled state. When the electrolytic solution 6 is allowed to stand for a long time, most of the powder 7 may be settled in the electrolytic solution 6. However, if the electrolytic solution 6 causes convection or the like, the powder 7 is settled. A part of the powder 7 is dispersed or suspended in the electrolyte 6. That is, the powder 7 is movably present in the electrolytic solution 6. Here, “movable” means that the powder 7 can move only in a local space formed between the surrounding other powders 7, but the powder 7 can be moved to another position in the electrolytic solution 6. The movement indicates that the powder 7 is exposed to the electrolyte 6 other than the initial position. Further, the movable category includes that the powder 7 can be moved to the vicinity of both the positive electrode 2 and the negative electrode 3 and that the powder 7 can be almost anywhere in the electrolytic solution 6 existing in the housing 17. That can be moved. When the [Zn (OH) ₄ ] ²⁻ dissolved in the electrolyte 6 is consumed, the powder 7 mixed in the electrolyte 6 is changed so that the powder 7 and the electrolyte 6 maintain an equilibrium state with each other. [Zn (OH) ₄ ] ^2- dissolved therein is dissolved so as to approach the saturation concentration. The powder 7 can maintain the ionic conductivity of the electrolytic solution 6 high while adjusting the zinc concentration in the electrolytic solution 6.

  The bubbles 8 are made of, for example, a gas that is inert to the positive electrode 2, the negative electrode 3, and the electrolytic solution 6. Examples of such a gas include a nitrogen gas, a helium gas, a neon gas, and an argon gas. By generating an inert gas bubble 8 in the electrolytic solution 6, denaturation of the electrolytic solution 6 can be reduced. Further, for example, it is possible to reduce the deterioration of the electrolytic solution 6 which is an alkaline aqueous solution containing a zinc species, and to maintain the ionic conductivity of the electrolytic solution 6 high. The gas may contain air.

  The bubbles 8 generated by the gas supplied from the generator 9 into the electrolytic solution 6 are generated between the electrodes arranged at predetermined intervals, more specifically, between the negative electrode 3a and the positive electrode 2, and between the positive electrode 2 and the negative electrode 3b. Floats in the electrolytic solution 6 between the two. The gas floating in the electrolyte 6 as bubbles 8 disappears at the liquid surface 6 a of the electrolyte 6, and forms a gas layer 13 between the upper plate 18 and the liquid surface 6 a of the electrolyte 6.

  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. Reaction formulas at the positive electrode 2 and the negative electrode 3 during charging are as follows, respectively.

The positive _{electrode: Ni (OH) 2 + OH} - → NiOOH + H 2 O + e -
Negative electrode: [Zn (OH) ₄ ] ²⁻ + 2e ⁻ → Zn + 4OH ⁻

Generally, there is a concern that dendrite generated in the negative electrode 3 accompanying this reaction grows toward the positive electrode 2 and the positive electrode 2 and the negative electrode 3 conduct. As is 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 in which the concentration of [Zn (OH) ₄ ] ^2- decreases in the vicinity of the deposited zinc is one of the factors that cause growth as dendrites. That is, by supplying [Zn (OH) ₄ ] ²⁻ in the electrolytic solution 6 consumed at the time of charging, a state in which the concentration of the zinc species [Zn (OH) ₄ ] ^{2− in} the electrolytic solution 6 is high. Is held. Thereby, the growth of dendrite is reduced, and the possibility of conduction between the positive electrode 2 and the negative electrode 3 is reduced.

  In the flow battery 1, 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 9 a of the generator 9 to generate bubbles 8. The bubbles 8 float in the electrolyte 6 from below to above the housing 17 between the negative electrode 3a and the positive electrode 2 and between the positive electrode 2 and the negative electrode 3b.

  In addition, as the bubbles 8 float between the electrodes, an ascending liquid flow is generated in the electrolytic solution 6, and the inner bottom of the reaction section 10 is formed 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. The rising liquid flow of the electrolytic solution 6 causes a descending liquid flow mainly between the inner wall 10a and the negative electrode 3a of the reaction section 10 and between the inner wall 10b and the negative electrode 3b. 10 flows downward from above in the interior of 10.

Thus, when in the electrolytic solution ^{_{6 [Zn (OH) 4]}} 2- is consumed by charging, a high concentration by zinc powder 7 is dissolved to follow to [Zn _{(OH) 4} The electrolyte solution 6 containing ^2- is supplied near the negative electrode 3. For this reason, [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 due to the growth of dendrite can be reduced. .

  The powder 7 includes, in addition to zinc oxide and zinc hydroxide, zinc metal, calcium zincate, zinc carbonate, zinc sulfate, zinc chloride, and the like, and zinc oxide and zinc hydroxide are preferable.

Further, in the negative electrode 3, Zn is consumed by the discharge and generates [Zn (OH) ₄ ] ²⁻ , but since the electrolytic solution 6 is already in a saturated state, the excess [Zn] in the electrolytic solution 6 is obtained. (OH) ₄ ] ZnO precipitates from ^2- . The zinc consumed at the negative electrode 3 at this time is zinc deposited on the surface of the negative electrode 3 during charging. Therefore, unlike the case where charge and discharge are repeated using the negative electrode originally containing the 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 according to the embodiment, the deterioration with time of the negative electrode 3 can be reduced. Depending on the state of the electrolytic solution 6, the precipitate from excess [Zn (OH) ₄ ] ²⁻ is Zn (OH) ₂ or a mixture of ZnO and Zn (OH) _2. .

  The flow battery 1 according to the embodiment will be further described. The generation unit 9 is arranged below the reaction unit 10. The inside of the generator 9 is hollow so as to temporarily store gas supplied from a supply unit 14 described later. Further, the inner bottom 10 e of the reaction section 10 is arranged so as to cover the hollow portion of the generation section 9, and also serves as the top plate 20 of the generation section 9.

  The generator 9 has a groove 11 formed in the top plate 20 and a discharge port 9a. The groove portion 11 and the discharge port 9a are respectively arranged between the negative electrode 3a and the positive electrode 2 and between the positive electrode 2 and the negative electrode 3b in plan view. Here, the groove 11 and the discharge port 9a of the top plate 20 will be described with reference to FIGS. FIG. 2 is a diagram schematically illustrating a top plate included in the flow battery according to the embodiment. FIG. 3 is a sectional view taken along the line II of FIG. 2, and FIG. 4 is a sectional view taken along the line II-II of FIG. FIG. 2 corresponds to a plan view of the top plate 20 of the generator 9 included in the flow battery 1 shown in FIG. 1 from the inner bottom 10e side. In FIG. 2, illustration of the diaphragms 4 and 5, the electrolytic solution 6, the powder 7, and the like is omitted for the purpose of simplifying the description. Further, the drawings may be omitted in other drawings used in the following description.

  A plurality of grooves 11 are arranged at predetermined intervals along the X-axis direction. The discharge port 9a is open on the bottom surface 11e of the groove 11. The gas supplied from the supply unit 14 (see FIG. 1) is discharged from the discharge port 9a to the inner bottom 10e through the groove 11.

  When the top plate 20 does not have the groove portion 11, for example, when foreign matter such as the metal zinc dropped from the negative electrode 3a and the powder 7 that has agglomerated or grown large particles stays on the inner bottom 10e so as to close the discharge port 9a, Discharge of the gas from the discharge port 9a is hindered. As a result, if the smooth circulation of the electrolytic solution 6 is hindered, there is a concern that performance may be deteriorated, for example, dendrite may easily grow during charging.

  On the other hand, as shown in FIGS. 2 and 3, even when the foreign matter 30 stays on the inner bottom 10e so as to cover the discharge port 9a in plan view, the gap between the discharge port 9a and the foreign matter 30 Has a groove 11 extending in the X-axis direction. In such a case, the bubbles 8 (see FIG. 1) generated by the gas discharged from the discharge port 9a pass through the gap between the foreign matter 30 and the groove portion 11 and float in the electrolyte solution 6 accommodated on the inner bottom 10e side. For this reason, smooth circulation of the electrolytic solution 6 is ensured, and for example, performance deterioration due to clogging of the discharge port 9a can be reduced.

  Here, referring to FIG. 3, the distance between the center line CL of the discharge port 9a and the inner peripheral surface of the discharge port 9a, that is, the radius A of the discharge port 9a is, for example, 0.025 mm or more and 0.25 mm or less, and 0.1 mm or less. It can be not less than 05 mm and not more than 0.1 mm. By defining the radius A as described above, it is possible to reduce the problem that the electrolyte 6 and the powder 7 enter the inside of the generation unit 9 from the discharge port 9a. Further, a pressure loss suitable for generating bubbles 8 can be given to the gas discharged from the discharge port 9a. On the other hand, if the radius A is less than 0.025 mm, there is a possibility that the electrolytic solution 6 does not flow to such an extent that it can be appropriately circulated in the reaction section 10. If the radius A exceeds 0.25 mm, the amount of gas discharged to the discharge port 9a per unit time increases, and there is a possibility that power consumption in the supply unit 14 (see FIG. 1) increases.

  The distance B between the center line CL and the end 11a of the groove 11 in the Y-axis direction is smaller than the distance C between the negative electrode 3a and the center line CL, for example. More specifically, by setting B ≦ ２ / 3 × C, bubbles 8 floating from the discharge port 9 a via the groove 11 can be more reliably guided between the positive electrode 2 and the negative electrode 3. . Further, by setting B ≦ １ ／ × C, the air bubbles 8 floating from the discharge port 9 a via the groove 11 can be more reliably guided between the positive electrode 2 and the negative electrode 3. 8, the flow of the electrolyte 6 on the positive electrode 2 side and the negative electrode 3 side becomes smoother.

  In addition, since the width of the groove 11 in the Y-axis direction is larger than the diameter of the discharge port 9a, the discharge port 9a is less likely to be blocked by a foreign material 30 that is about as large as the width of the groove 11. In addition, since the foreign matter 30 often has an irregular shape, it is unlikely that the entire foreign matter 30 is blocked by the large foreign matter 30.

  Referring to FIG. 2, the distance between both ends in the width direction of negative electrode 3 in groove 11 is smaller than the width of negative electrode 3. Specifically, one end 3e of the negative electrode 3 on the negative side of the X-axis is closer to the inner wall of the reaction unit 10 on the negative side of the X-axis by a width D than one end 11b of the groove 11 located at the end on the negative side of the X-axis. (Not shown). For example, width D ≧ radius A, more specifically, D ≧ 2 mm, and D ≧ 5 mm. This makes it possible to more reliably secure a path in which the electrolytic solution 6 that has risen between the electrodes descends, and the flow of the electrolytic solution 6 becomes smoother. In the example shown in FIG. 2, the positive electrode 2 and the negative electrodes 3a and 3b are illustrated as having the same width in the X-axis direction. However, the width is not limited to this and may be different. In such a case, of the positive electrode 2 and the negative electrodes 3a and 3b, the width D may be defined based on the one having the smallest width in the X-axis direction.

  Further, if the depth E of the groove 11 is at least 0.5 mm at least in a portion where the discharge port 9a is disposed, when the foreign matter 30 is present above the discharge port 9a, the depth E is changed from the discharge port 9a to the groove 11. Bubbles 8 can easily enter. Further, the depth E can be set according to the strength of the top plate 20 and the degree of difficulty in processing. Specifically, the depth E can be set to 0.5 mm or more and 2 mm or less, for example, 1 mm, but is not limited to this. For example, the depth E may be less than 0.5 mm, or may be more than 2 mm.

  Referring to FIG. 4, the distance F between the centers of the discharge ports 9a adjacent in the X-axis direction is, for example, not less than 2.5 mm and not more than 50 mm, and may be not more than 10 mm.

  The distance G between the center line CL and the end 11c of the groove 11 in the X-axis direction can be, for example, G ≦ 5 × A, more specifically, 2 mm or less. Thereby, the positional accuracy in the X-axis direction of the bubbles 8 floating from the discharge ports 9a via the grooves 11 is increased, and the flow of the electrolytic solution 6 becomes smoother. In particular, by setting G ≦ １ ／ × F, the movable range of the bubble 8 from the discharge port 9a in the X-axis direction until the foreign matter staying at the discharge port 9a or the like and floating from the groove 11 is bypassed. Will have an upper limit. Accordingly, the displacement of the floating position of the bubble 8 with respect to the discharge port 9a is reduced, so that the flow of the electrolytic solution 6 floating between the electrodes becomes smoother.

  In addition, the distance H between the adjacent grooves 11 in the X-axis direction is not particularly limited in size from the viewpoint of making it difficult for the bubbles 8 to move to the adjacent grooves 11. If the interval H is, for example, 6 mm or more, the bubbles 8 can be evenly floated over the whole in the X-axis direction, and the flow of the electrolytic solution 6 becomes smoother.

  In addition, the groove 11 and the discharge port 9a can be formed by grinding the top plate 20, but the processing method is not particularly limited as long as the groove 11 can be appropriately formed, such as injection molding. It may be processed by any method.

  Returning to FIG. 1, the flow battery 1 according to the embodiment will be further described. The supply unit 14 supplies the gas recovered from the inside of the housing 17 via the pipe 16 to the generation unit 9 via 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 unlikely to be reduced due to leakage of gas and water vapor derived from the electrolytic solution 6 to the outside.

  The housing 17 including the top plate 20 and the upper plate 18 are made of, for example, an alkali-resistant and insulating resin material such as polystyrene, polypropylene, polyethylene terephthalate, and polytetrafluoroethylene. The housing 17 and the upper plate 18 are preferably made of the same material as each other, but may be made of different materials. Further, the top plate 20 may be formed integrally with the housing 17, and the top plate 20 and the housing 17 may be integrated by a post-process such as joining.

  Next, connection between the electrodes in the flow battery 1 will be described. FIG. 5 is a diagram illustrating an example of a connection between electrodes of the flow battery 1 according to the embodiment.

  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 in this manner, the respective 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.

  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. As described above, in the flow battery 1 in which the two negative electrodes 3a and 3b correspond to one positive electrode 2, the current density per one negative electrode is smaller than that in the flow battery in which the positive electrode 2 and the negative electrode 3 correspond to each other at a ratio of 1: 1. Decrease. For this reason, according to the flow battery 1 according to the first embodiment, since the generation of dendrites in the negative electrodes 3a and 3b is further reduced, the conduction between the negative electrodes 3a and 3b and the positive electrode 2 can be further reduced. .

  In the flow battery 1 shown in FIG. 1, a total of three electrodes are configured such that the negative electrode 3 and the positive electrode 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. May be arranged one by one. Further, in the flow battery 1 shown in FIG. 1, both ends are configured to be the negative electrode 3. However, the present invention is not limited thereto, and the both ends may be configured to be the positive electrode 2.

<First Modification>
FIG. 6 is a diagram schematically illustrating a configuration of a top plate included in a flow battery according to a first modification of the embodiment. The top plate 20 shown in FIG. 6 has the same configuration as the top plate 20 shown in FIG. 2 except that the top plate 20 shown in FIG. In other words, the groove 11 is within the range where the discharge port 9a exists in the Y-axis direction. The width of the groove 11 in the Y-axis direction may be 以下 or less times the diameter of the discharge port 9a, or may be に し て も or less. As described above, by limiting the axial width of the groove 11, the positional accuracy in the Y-axis direction of the bubble 8 that floats from the discharge port 9a via the groove 11 as compared with the groove 11 shown in FIG. Further, the air bubbles 8 can be more reliably induced between the positive electrode 2 and the negative electrode 3.

<Second Modification, Third Modification>
FIGS. 7 and 8 are diagrams schematically illustrating the configuration of a top plate included in a flow battery according to a second modification and a third modification of the embodiment, respectively. In the top plate 20 shown in FIGS. 7 and 8, a plurality of discharge ports 9a arranged at a predetermined interval along the X-axis direction are arranged in one groove portion 11 extending in the X-axis direction. Except for this, each has the same configuration as the top plate 20 shown in FIGS. Thus, even with the groove 11 extending in the X-axis direction, the air bubbles 8 floating from the discharge port 9 a via the groove 11 can be guided between the positive electrode 2 and the negative electrode 3.

<Fourth modification>
FIG. 9 is a diagram schematically illustrating a configuration of a top plate included in a flow battery according to a fourth modification of the embodiment. The top plate 20 shown in FIG. 9 has a groove 11 disposed between the positive electrode 2 and the negative electrode 3 in plan view, a first groove 111 disposed closer to the negative electrode 3 and a second groove disposed closer to the positive electrode 2. 112. Further, the top plate 20 shown in FIG. 9 is configured such that the discharge ports 9 a formed for each of the grooves 11 have the first discharge ports 9 a 1 formed in the first grooves 111 and the second discharge ports 9 a formed in the second grooves 112. Outlet 9a2. Even when a plurality of outlets 9a are arranged in the Y-axis direction in this manner, by arranging the grooves 11 extending in the X-axis direction, the bubbles 8 floating from the outlets 9a via the grooves 11 are formed. It can be guided between the positive electrode 2 and the negative electrode 3. Further, the bubbles 8 discharged from the first discharge port 9a1 and the second discharge port 9a2, respectively, are accurately guided between the positive electrode 2 and the negative electrode 3, so that the bubbles 8 are integrated and the flow of the electrolytic solution 6 is impeded. The problem of uniformity can be reduced. Note that FIG. 9 illustrates an example in which a plurality of the groove portions 11 and the discharge ports 9a provided in the top plate 20 illustrated in FIG. 2 are arranged in the Y-axis direction. A plurality of provided grooves 11 and discharge ports 9a may be arranged in the Y-axis direction.

<Fifth modification>
FIGS. 10 and 11 are cross-sectional views schematically illustrating a configuration of a top plate included in a flow battery according to a fifth modification of the embodiment. The top plate 20 shown in FIGS. 10 and 11 is shown in FIG. 6 except that the end 11d in the X-axis direction of the groove 11 is inclined with respect to the inner bottom 10e extending along the XY plane. It has the same configuration as the groove 11. In other words, the groove 11 is inclined such that the depth decreases toward the end in the X-axis direction at the end 11d in the X-axis direction. The inclination may be at only one end on the positive side or the negative side in the X-axis direction, or may be at both ends. The inclination may not be provided in the entire groove 11, and the bottom surface of the groove 11 may be substantially parallel to the inner bottom 10 e at the center of the groove 11 in the X-axis direction.

  Further, in the embodiment shown in FIG. 7 or FIG. 8, the groove 11 may be as follows. That is, of the plurality of outlets 9a arranged in the groove 11, the end 11d may be inclined at the end in the X-axis direction more than the endmost outlet 9a in the X-axis direction. . Then, in the X-axis direction, the bottom surface of the groove 11 within the range where the discharge port 9a exists may be substantially parallel to the inner bottom 10e.

  Further, in the example shown in FIG. 10, the inclination of the end portion 11d is shallow so that the depth becomes asymptotically zero toward the end in the X-axis direction. As another mode, the inclination of the end portion 11d may be shallower toward the end in the X-axis direction so that the depth becomes a predetermined value.

  Due to the foreign matter 30 staying in the upper part of the discharge port 9a, the bubbles 8 which cannot float and head toward the end 11d in the groove 11 work to get out of the groove 11 due to the shallow depth of the groove 11. The force increases, and it is more likely to come out of the groove 11 before reaching a portion where the groove 11 no longer exists. That is, by inclining the end 11d of the groove 11 as described above, the positional accuracy in the X-axis direction of the bubble 8 floating from the discharge port 9a via the groove 11 is further improved.

  Here, the width N in the X-axis direction of the groove 11 opened in the inner bottom 10e can be, for example, not less than 3 times and not more than 50 times the diameter M (= A × 2) of the discharge port 9a. The width P of the groove 11 in the Y-axis direction can be, for example, not less than 0.01 times and not more than 0.1 times the width N. By defining the width of the groove 11 in the X-axis direction and the Y-axis direction in this way, the positional accuracy in the X-axis direction and the Y-axis direction of the bubble 8 floating from the discharge port 9a via the groove 11 is further increased, The bubbles 8 can be more reliably induced between the positive electrode 2 and the negative electrode 3.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various changes can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the description has been made assuming that the powder 7 is mixed in the electrolytic solution 6. However, the present invention is not limited to this, and the powder 7 may not be provided. In such a case, the amount of the negative electrode active material contained in the negative electrode 3 may be increased.

  In the above-described embodiment, the diaphragms 4 and 5 have been described as being arranged so as to sandwich both sides in the thickness direction of the positive electrode 2. However, the present invention is not limited to this, and the positive electrode 2 may be covered. Further, the diaphragms 4 and 5 are not necessarily required to be arranged.

  The supply unit 14 is preferably operated at all times from the viewpoint of preventing clogging of the discharge port 9a. However, from the viewpoint of reducing power consumption, the gas supply rate may be lower during discharging than during charging.

  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 may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Flow battery 2 Positive electrode 3, 3a, 3b Negative electrode 4, 5 Diaphragm 6 Electrolyte solution 7 Powder 8 Bubbles 9 Generation part 9a Discharge port 10 Reaction part 11 Groove part 14 Supply part 17 Housing 18 Top plate 20 Top plate

Claims (12)

A positive electrode and a negative electrode,
An electrolyte that contacts the positive electrode and the negative electrode,
A groove extending in the width direction of the negative electrode, having a discharge port for discharging a gas into the electrolytic solution from the bottom surface of the groove to generate bubbles, and a generating unit disposed below the positive electrode and the negative electrode; A flow battery comprising:   2. The flow battery according to claim 1, wherein an interval between an end of the groove in a thickness direction of the negative electrode and the discharge port is smaller than an interval between the negative electrode and the discharge port. 3.   The flow battery according to claim 1, wherein the groove has a width in a thickness direction of the negative electrode that is larger than a diameter of the discharge port.   3. The flow battery according to claim 1, wherein the width of the groove in the thickness direction of the negative electrode is equal to or less than the diameter of the discharge port. 4.   5. The groove according to claim 1, wherein at a widthwise end of the negative electrode, the groove is inclined so that a depth decreases toward a widthwise end of the negative electrode. 6. 3. The flow battery according to 1.   The flow battery according to claim 1, wherein a distance between both ends of the groove in the width direction of the negative electrode is smaller than a width of the negative electrode. The plurality of grooves are arranged along the width direction of the negative electrode,
The flow battery according to any one of claims 1 to 6, wherein the discharge port is arranged for each of the grooves. The plurality of grooves are arranged in the thickness direction of the negative electrode,
The flow battery according to any one of claims 1 to 7, wherein the discharge port is arranged for each of the grooves.   The flow battery according to any one of claims 1 to 8, wherein the discharge port is disposed between the positive electrode and the negative electrode in plan view.   The flow battery according to any one of claims 1 to 9, wherein the groove is disposed between the positive electrode and the negative electrode in a plan view. The negative electrode includes a first negative electrode and a second negative electrode that face each other across the positive electrode,
The flow cell according to any one of claims 1 to 10, wherein the air bubbles float between the first negative electrode and the positive electrode and between the positive electrode and the second negative electrode. The flow battery according to any one of claims 1 to 11, further comprising a powder containing zinc and movably mixed in the electrolytic solution.

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