Flow type battery cell

Abstract

To provide a flow type battery cell that reduces the energy consumption of a pump.SOLUTION: A flow type battery cell according to the present disclosure includes a slurry containing a solid active material and an electrolyte, an anode chamber to which the slurry is supplied, a cathode chamber to which air is supplied, and a liquid supply control unit for changing the supply speed of the slurry.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a flow type battery cell. [Background technology]

[0002] Battery cells have been disclosed in the past.

[0003] For example, Non-Patent Document 1 discloses a battery using zinc slurry uniformly dispersed with a binder. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Metal-Air Batteries: Present and Perspectives Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the battery of Non-Patent Document 1, increasing the weight ratio of zinc, which is an active material, increases the viscosity, and increases the energy consumption of the pump due to pressure loss.

[0006] In view of the above problems, an object of the present disclosure is to provide a flow type battery cell that reduces the energy consumption of the pump without reducing battery performance. [Means for solving the problem]

[0007] A flow type battery cell according to the present disclosure includes a slurry containing a solid active material and an electrolyte, an anode chamber to which the slurry is supplied, a cathode chamber to which air is supplied, and a liquid supply control unit for changing a supply speed of the slurry; The present invention is characterized by comprising: Effect of the Invention

[0008] As described above, according to the present disclosure, it is possible to provide a flow type battery cell in which the energy consumption of the pump is suppressed without degrading the battery performance. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of a flow type battery cell according to the present disclosure. [Diagram 2] FIG. 2 is a diagram showing the thickener concentration and the solution viscosity (electrolyte). [Diagram 3] FIG. 3 is a schematic cross-sectional view showing a modification of the flow type battery cell shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a preferred embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the present embodiment described below does not unduly limit the contents of the present disclosure described in the claims, and not all of the configurations described in the present embodiment are necessarily essential as the solution of the present disclosure. Note that, in the drawings, X, Y, and Z axes are shown, and in particular, the Z axis indicates the direction of gravity (height direction) of the flow type battery cell.

[0011] The flow type battery cell 100 according to the present disclosure is, for example, a flow type metal-air battery. The flow type battery cell 100 takes in air and generates electricity using the air in a power generation section (not shown). Then, the battery is charged in a charging section (not shown) and the air is discharged.

[0012] The flow type battery cell 100 is a flow type battery in which slurry flows in a negative electrode chamber, which will be described later. The configuration of the flow type battery cell will be described below.

[0013] Fig. 1 is a schematic cross-sectional view of a flow type battery cell 100 according to the present disclosure. As shown in Fig. 1, the flow type battery cell 100 according to the present disclosure includes a slurry 10, a negative electrode chamber 20, a negative electrode current-carrying plate 21, a negative electrode 22, a negative electrode flow path layer 23, a gasket 24, a positive electrode chamber 30, a positive electrode 31, a positive electrode current-carrying plate 32, a separator 50, a sealing unit 60, and a liquid supply control unit 40. The flow type battery cell 100 according to the present disclosure is produced by stacking these components.

[0014] The negative electrode chamber 20 is supplied with the slurry 10 described below. The negative electrode chamber 20 is a space partitioned by the separator 50, the negative electrode flow path layer 23, and the negative electrode 22. The negative electrode chamber 20 can have various shapes depending on the negative electrode 22 and the negative electrode flow path layer 23.

[0015] The negative electrode current-carrying plate 21 is made of a conductive material that allows current to flow between the negative electrode 22. The negative electrode current-carrying plate 21 may have any shape.

[0016] The negative electrode 22 is made of a material that is conductive and resistant to corrosion by the slurry 10. As shown in FIG. 1, the negative electrode 22 and the negative electrode current-carrying plate 21 may be formed of separate members, or the negative electrode 22 may also serve as the negative electrode current-carrying plate 21.

[0017] The negative electrode flow path layer 23 may be sandwiched between the separator 50 and the negative electrode 22 and / or the negative electrode current-carrying plate 21. The negative electrode 22 may also serve as the negative electrode flow path layer 23.

[0018] The gasket 24 is sandwiched between the negative electrode flow path layer 23 and the negative electrode 22 and / or the negative electrode current-carrying plate 21 to prevent leakage of the slurry 10.

[0019] Air is supplied to the positive electrode chamber 30. The positive electrode chamber 30 is a space partitioned by a positive electrode 31 and a positive electrode current-carrying plate 32. The positive electrode chamber 30 can take various shapes depending on the positive electrode current-carrying plate.

[0020] The positive electrode 31 is made of a conductive material, and its shape is not limited.

[0021] The positive electrode current-carrying plate 32 is made of a conductive material that allows current to flow between the positive electrode 31 and the plate.

[0022] Furthermore, in the case of a stack structure in which a plurality of flow type battery cells 100 are stacked, the negative electrode current-carrying plate 21 and the positive electrode current-carrying plate 32 of adjacent cells may be formed from a single member called a bipolar plate.

[0023] The separator 50 is provided between the negative electrode flow path layer 23 and the positive electrode 31 to prevent contact between the solid active material 11 in the slurry 10 and the positive electrode 31 .

[0024] The sealing portion 60 is provided between the anode flow path layer 23 and the positive electrode current conductor 32. The sealing portion 60 may be frame-shaped, or may be disposed on the edge of the anode flow path layer 23 and the positive electrode current conductor 32. In this manner, the sealing portion 60 prevents the slurry 10 from flowing into the positive electrode chamber 30 due to the pressing between the anode flow path layer 23 and the positive electrode current conductor 32.

[0025] The slurry 10 contains an electrolytic solution 12 and active materials. The active materials include those dissolved in the electrolytic solution 12 and solid active materials 11 that do not dissolve in the electrolytic solution 12 beyond their saturation solubility and have electronic conductivity.

[0026] The active material is a negative electrode active material. The negative electrode active material is a metal species. The metal species is, for example, a zinc species, a cadmium species, a lithium species, a sodium species, a magnesium species, a lead species, a tin species, an aluminum species, or an iron species. The metal species may be a metal consisting of only a metal that is a main component, or may be an alloy of a metal that is a main component and a subcomponent. The metal species may be either a metal or an oxide. Whether the metal species is a metal or an oxide is determined according to the degree of progress of the discharge reaction or the charge reaction.

[0027] When the flow battery cell 100 is shipped, the metal species may be in either a metal or an oxide state. The oxidation state of the metal species may be uniform within the negative electrode active material, or may be non-uniform within the negative electrode active material. For example, when a discharge reaction or a charge reaction proceeds from the surface to the center of the negative electrode active material, the oxidation state of the metal species on the surface of the negative electrode active material may be different from the oxidation state of the metal species in the center of the negative electrode active material.

[0028] In this embodiment, the metal species is a zinc species, and a zinc-air battery is used as the flow type battery cell 100. The metal constituting the zinc species may be, for example, a metal consisting of only zinc as a main component, or may be an alloy of zinc as a main component and a subcomponent.

[0029] The average particle diameter of the metal species is several μm when it is an oxide (e.g., ZnO) in an oxidized state, and is several tens of μm to about 300 μm when it is a reduced state (e.g., Zn) that is not an oxide. The average particle diameter can be measured by a particle size distribution measuring device. The particle size distribution measuring device measures the particle size distribution by, for example, a laser diffraction / scattering method, and calculates the median diameter D50 as the average particle diameter from the measured particle size distribution.

[0030] The electrolyte 12 is selected according to the metal species. When the metal species is zinc, the electrolyte 12 is an alkaline aqueous solution, such as a potassium hydroxide aqueous solution or a sodium hydroxide aqueous solution. When the metal species is lithium, the electrolyte 12 is a non-aqueous electrolyte. When the metal species is magnesium, the electrolyte 12 is a neutral aqueous solution, such as a sodium chloride aqueous solution.

[0031] The slurry 10 includes a solid active material 11. In the case of an electrolyte 12, which is a solvent of a metal species such as zinc species and a strong alkaline aqueous solution such as an aqueous potassium hydroxide solution, when the concentration of the metal species such as zinc oxide and zinc is equal to or lower than the saturation solubility, the metal species dissolve, and when the concentration of the metal species such as zinc oxide and zinc is higher than the saturation solubility, the metal species such as zinc oxide and zinc do not dissolve and exist as the solid active material 11. In addition, the solid active material particles can be determined by appearance. When the electrolyte contains solid active material particles (not dissolved beyond saturation), the electrolyte becomes a suspension, which is white when the active material is zinc oxide. On the other hand, when the active material is a saturated solution, it is transparent because it is dissolved. For analysis, there is a method of measuring the particle size distribution, and laser diffraction, dynamic light scattering, etc. are used. In this embodiment, a suspension of metal species such as zinc oxide and zinc is used. Furthermore, the solid active material 11 has a larger electrical capacity per unit volume than an active material dissolved in an electrolyte, and therefore, by supplying a small amount of slurry 10, the solid active material 11 required for the reaction can be supplied in excess to the negative electrode chamber 20. This allows the supply of the slurry 10 to be temporarily stopped, thereby reducing the power consumption of the pump.

[0032] In the present embodiment, the concentration of the solid active material 11 in the slurry 10 is 5 wt% or more and 50 wt% or less. Also, it is preferably 10 wt% to 30 wt%. By making the concentration 5 wt% or more, an electronic conduction path between the solid active materials 11 can be effectively formed. Furthermore, by making the concentration 50 wt% or less, the viscosity of the slurry 10 can be prevented from becoming too high, and the power consumption of the pump can be reduced.

[0033] The flow type battery cell 100 according to the present disclosure is a discharge cell. During discharge, an oxidation reaction of the solid active material (represented by formula (1) below) occurs in the negative electrode 22, and a reduction reaction of oxygen (represented by formula (2) below) occurs in the positive electrode 31.

[0034] Zn+4OH - →Zn(OH)4 2- +2e - →ZnO+H2O + +2OH - 2e - (1) 1 / 2O2+H2O+2e- →2OH - (2)

[0035] When the metal species is zinc, in formula (1), the solid active material, metallic zinc, undergoes an oxidation reaction to become zincate ions, which then become zinc oxide. In formula (2), it undergoes a reduction reaction with oxygen to become hydroxide ions.

[0036] The liquid supply control unit 40 changes the supply speed of the slurry 10. The liquid supply control unit 40 may be a control device such as a controller that controls the output of a pump, and the supply speed of the slurry 10 may be controlled by the output of the pump or the like.

[0037] In this manner, in the flow type battery cell 100 according to the present disclosure, the liquid feed control unit 40 changes the supply speed of the slurry 10, thereby providing a period in which the liquid feed speed of the slurry 10 containing the solid active material 11 is temporarily increased to transport the solid active material 11, and a period in which the liquid feed speed is reduced to allow the solid active material 11 to settle. The reduction in the liquid feed speed causes the solid active material 11 to settle, and a large number of particles of the solid active material 11 come into contact with each other to form an electronic conduction path. In addition, the contact with the negative electrode 22 increases the reaction area of ​​the negative electrode. In this manner, it is possible to reduce the power consumption of the pump without deteriorating the battery performance.

[0038] 1, the flow type battery cell 100 according to this embodiment further includes a slurry storage tank 70. The slurry storage tank 70 may store the slurry 10 to be supplied to the anode chamber 20. The slurry 10 may be supplied from the slurry storage tank 70 to the anode chamber 20.

[0039] The slurry storage tank 70 may be equipped with an agitator 71 .

[0040] FIG. 2 is a diagram showing the relationship between the thickener concentration and the solution viscosity (electrolyte 12). 7 mol / L KOH is used for the electrolyte 12, 4 wt% ZnO is used for the active material, and Carbopol 690 (manufactured by Lubrizol) is used for the thickener. The viscosity can be measured using a viscometer. For example, the viscometer is a Viscotester VT-06 manufactured by Rion Co., Ltd., and the measurement is performed using one of rotors No. 1 to No. 3.

[0041] The slurry 10 preferably contains a thickener. Since the difference in specific gravity between the electrolyte 12 and the solid active material 11 is very large, the electrolyte 12 and the solid active material 11 are separated in a very short time. As shown in FIG. 2, the addition of a thickener increases the viscosity of the solution. In other words, by including a thickener, the settling speed of the solid active material 11 is reduced, and the solid active material 11 can be uniformly dispersed in the slurry 10 even over time. The slurry 10 may also contain a gelling agent.

[0042] The concentration of the thickener in the slurry 10 is preferably 0.75 wt% or more and less than 3 wt%, and more preferably 1 wt% or more and less than 2 wt%. If the concentration is less than 0.75 wt%, the settling speed of the solid active material 11 is too fast, and the flow rate needs to be increased to transport the solid active material 11, resulting in high power consumption by the pump. If the concentration is 3 wt% or more, the viscosity is too high, and the pressure loss during delivery is large, resulting in high power consumption by the pump.

[0043] The viscosity of the electrolyte 12 is preferably 10 mPa·s to 300 mPa·s. If the viscosity is less than 10 mPa·s, the settling speed of the solid active material 11 is too fast, and the flow rate must be increased to transport the solid active material 11, resulting in increased power consumption by the pump. If the viscosity is more than 300 mPa·s, the viscosity becomes high, and the pressure loss during slurry delivery becomes large, resulting in increased power consumption by the pump.

[0044] The viscosity of the slurry 10 is preferably 100 mPa·s to 3000 mPa·s. If the viscosity is too low, the settling speed of the solid active material 11 is high. It is necessary to increase the frequency of the flow rate to transport the settled solid active material 11, and the power consumption of the pump tends to increase. On the other hand, if the viscosity is too high, the pressure loss during the solid active material 11 slurry delivery increases, and the power consumption of the pump increases. In addition, since the solid active material 11 does not settle and maintains a dispersed state, the negative electrode 22 and the solid active material 11 do not come into contact with each other, and the particles of the contacted solid active material 11 cannot be connected to each other and come into contact with other solid active material 11 particles (the number of active material particles that are conductive with the negative electrode 22 decreases, and the formation of an electronic conduction path is reduced), and an electronic conduction path from the solid active material 11 to the negative electrode 22 cannot be formed, and the utilization efficiency of the active material decreases. Therefore, within the above range, excessive settling speed of the solid active material 11 is suppressed, power consumption of the pump is suppressed, pressure loss during liquid delivery is suppressed, and the utilization efficiency of the active material is improved.

[0045] The average particle size of the metal species has been described above, but the average particle size of the non-oxide reduced solid active material 11 is preferably 30 μm to 300 μm. If it is less than 30 μm, the particles of the solid active material 11 are unlikely to come into contact with each other, making it difficult to form an electron conduction path. If it is more than 300 μm, the settling speed of the solid active material 11 is high, and the flow rate must be increased to transport the settled particles of the solid active material 11, resulting in high power consumption by the pump.

[0046] Fig. 3 is a schematic cross-sectional view showing a modified example of the flow type battery cell 100 shown in Fig. 1. As shown in the flow type battery cell 110 in Fig. 3, the negative electrode 22 is arranged in the direction downward in the direction of gravity with respect to the positive electrode chamber 30. In this way, the solid active material 11 settles onto the negative electrode 22, so that an electronic conduction path from the solid active material 11 to the negative electrode 22 can be effectively formed. As a result, the electric capacity can be further improved.

[0047] The liquid supply control unit 40 preferably reduces the supply speed of the slurry 10 or stops the supply during power generation. In this way, the power consumption of the pump can be reduced. When the supply speed of the slurry 10 is reduced, the flow of the slurry is maintained, so that the solid active material 11 in the slurry 10 can be prevented from adhering and accumulating in the negative electrode chamber. When the supply speed of the slurry 10 is stopped, the power consumption of the pump can be reduced to zero.

[0048] During power generation, the liquid supply control unit 40 preferably has a time period during which the supply rate of the slurry 10 is reduced longer than the time during which the slurry 10 is supplied, and more preferably has a time period during which the supply of the slurry 10 is stopped longer than the time during which the slurry 10 is supplied. In this way, the deposition of the solid active material 11 is promoted, and an electron conduction path from the solid active material 11 to the negative electrode can be effectively constructed. In addition, since the supply rate of the slurry 10 is reduced or the supply is stopped, the power consumption of the pump can be reduced.

[0049] It is preferable that the liquid delivery control unit 40 periodically changes the supply rate during power generation. In this way, the slurry 10 can be efficiently delivered to the anode chamber 20, and power generation can be efficiently performed. The liquid delivery control unit 40 may also periodically change the supply / non-supply (supply / stop) during power generation. "Periodic" means that the supply rate is changed or the supply is turned on or off a number of times at any time interval.

[0050] The agitator 71 preferably operates cyclically.

[0051] Furthermore, it is preferable that the operation of the agitator 71 is synchronized with the liquid feed control unit 40. For example, when the liquid feed control unit 40 is supplying the slurry 10, the agitator 71 operates. On the other hand, when the liquid feed control unit 40 stops the supply of the slurry 10, the agitator 71 stops. In addition, the agitation by the agitator 71 does not have to be performed simultaneously with the liquid feed, and may be performed at an arbitrary time lag from the switching of the liquid feed. In addition, when the liquid feed control unit 40 periodically changes the supply / non-supply (supply / stop), the agitator 71 also periodically turns on and off the agitation accordingly.

[0052] The settling velocity of the solid active material 11 follows Stokes' equation below. v s =D p 2 (ρ p -ρ f )g / 18η v s : Terminal velocity of a particle D p : Particle size ρ p :Particle density ρ f : Fluid density g:Gravity acceleration η: Fluid viscosity

[0053] If the distance from the separator 50 to the negative electrode 22 is L (cm) and the period of change in the supply rate is T (s), then It is preferable to satisfy T>L×35. The settling speed of the solid active material 11 is determined by the particle size, density, and viscosity according to Stokes' equation, and the settling of the solid active material 11 forms an electronic conduction path with the negative electrode 22. Therefore, if the period of change in the supply speed is small relative to the settling speed and the settling distance, which is the distance from the separator 50 to the negative electrode 22, it is difficult to form a sufficient electronic conduction path, resulting in poor battery performance. In the Stokes' equation, when the particle size is 300 μm, the viscosity of the fluid is 10 mPa s, and the density of the fluid is 1.34 g / cm 3 , particle density 7.14, g / cm 3 The calculated settling velocity v sis 2.842×10^(-2) m / s. The period of the change in the supply rate refers to the period of "fast / slow" or "present / absent" in the supply of slurry 10, and it is sufficient if the supply rate is slightly different.

[0054] For example, when the distance L from the separator 50 to the negative electrode 22 is 1 cm, if the period T of the change in the supply rate is 30 sec, the average discharge voltage is low, while if the period T is 60 sec, the average discharge voltage is high. Also, when the distance L is 0.5 cm, if the period T is 10 sec, the average discharge voltage is low, while if the period T is 20 sec, the average discharge voltage is high.

[0055] Also, when the solid active material 11 is zinc, if the volume in the negative electrode chamber 20 is S (cm 3 ), the density of the slurry 10 is ρ (g / cm 3 ), the discharge current is I (A), and the weight ratio of zinc in the slurry 10 is X (wt%), then it is preferable to satisfy S×ρ×(X / 100) / 65.4 > I×T / (96500×2). That is, this means that the amount of zinc consumed when discharging for only the period T is less than the total amount of zinc present in the negative electrode chamber 20. If the amount of zinc particles present in the negative electrode chamber 20 is less than the amount of zinc particles consumed when discharging with the current I for the period T, there will be a tendency that the zinc available for discharge will be completely depleted and discharge will not be possible, so it is preferable to satisfy the above formula.

[0056] Also, in (S×ρ×(X / 100) / 65.4)×M > I×T / (96500×2), it is more preferable to satisfy 1 / 10 < M < 1 / 2, and even more preferable to satisfy 1 / 5 < M < 1 / 3. When M is less than 1 / 10, the period T becomes short and the power consumption of the pump increases. When M is 1 / 2 or more, the zinc oxide deposited in the slurry 10 present in the negative electrode chamber 20 may act as a resistance and the discharge voltage may decrease. By setting it within the above range, it is possible to prevent a decrease in battery performance while suppressing the power consumption of the pump.

[0057] If the ratio of the flow time during which the slurry supply rate is reduced or the flow (supply) is stopped to the period of change of the slurry supply rate is α, It is preferable that 0.4<α<0.97 is satisfied. In this way, the solid active material 11 can form a sufficient electron conduction path, and the utilization efficiency of the active material can be improved.

[0058] As described above, the flow type battery cells 100, 110 according to the present disclosure can improve the electrical capacity and reduce the energy consumption of the pump.

[0059] Although each embodiment and each example of the present disclosure have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure.

[0060] For example, a term described at least once in the specification or drawings together with a different term having a broader or similar meaning can be replaced with the different term anywhere in the specification or drawings. In addition, the configuration and operation of the flow type battery cell are not limited to those described in each embodiment and each example of the present disclosure, and various modifications are possible. [Explanation of symbols]

[0061] 10 slurry, 11 solid active material, 12 electrolyte, 20 negative electrode chamber, 21 negative electrode current-carrying plate, 22 negative electrode, 23 negative electrode flow path layer, 24 gasket, 30 positive electrode chamber, 31 positive electrode, positive electrode current-carrying portion 32, 40 Liquid delivery control unit, 50 separator, 60 sealing portion, 70 slurry storage tank, 71 agitator, 100, 110 Flow type battery cells, L Distance from separator to negative electrode

Claims

1. A slurry containing a solid active material and an electrolyte; an anode chamber to which the slurry is supplied; A positive electrode chamber for supplying air; A liquid supply control unit for changing a supply speed of the slurry; A flow type battery cell comprising:

2. The flow type battery cell according to claim 1 , wherein the slurry contains a thickener.

3. 3. The flow type battery cell according to claim 1, wherein the viscosity of the electrolyte is 10 mPa·s to 300 mPa·s.

4. 3. The flow type battery cell according to claim 1, wherein the viscosity of the slurry is 100 mPa·s to 3000 mPa·s.

5. 3. The flow type battery cell according to claim 1, wherein the solid active material has an average particle size of 30 μm to 300 μm.

6. Further comprising a negative electrode, 3. The flow type battery cell according to claim 1, wherein the negative electrode is disposed downwardly from the positive electrode chamber in a direction perpendicular to gravity.

7. 3. The flow type battery cell according to claim 1, wherein the liquid supply control unit reduces a supply speed of the slurry or stops the supply during power generation.

8. The flow type battery cell according to claim 7 , wherein the liquid supply control unit stops the supply of the slurry during power generation.

9. The flow type battery cell according to claim 7 , wherein the liquid supply control unit reduces the supply rate of the slurry for a longer period of time during power generation.

10. 9. The flow type battery cell according to claim 8, wherein the liquid supply control unit controls the supply of the slurry to be stopped for a period longer than the supply of the slurry during power generation.

11. 3. The flow type battery cell according to claim 1, wherein the liquid supply control unit periodically changes the supply speed during power generation.

12. 3. The flow type battery cell according to claim 1, wherein a concentration of the solid active material in the slurry is 5 wt % to 50 wt %.

13. A slurry storage tank is further provided, 3. The flow type battery cell according to claim 1, wherein the slurry storage tank is equipped with an agitator.

14. The flow type battery cell according to claim 13 , wherein the agitator operates periodically.

15. The flow type battery cell according to claim 13 , wherein the operation of the agitator is synchronized with the liquid supply control unit.

16. A negative electrode; a separator separating the negative electrode chamber and the positive electrode chamber; Further equipped with When the distance from the separator to the negative electrode is L (cm) and the period of change in the supply rate is T (s), The flow type battery cell according to claim 11, characterized in that T>L×35 is satisfied.

17. The solid active material contains zinc, The volume of the negative electrode chamber is S (cm ３ ), the density of the slurry is ρ (g / cm ３ ), the discharge current is I (A), and the weight ratio of the zinc in the slurry is X (wt%), The flow type battery cell according to claim 11, characterized in that S × ρ × (X / 100) / 65.4 > I × T / (96500 × 2) is satisfied.

18. If the ratio of the flow time during which the slurry supply rate is reduced or the flow is stopped is α, The flow type battery cell according to claim 11, characterized in that 0.4<α<0.97 is satisfied.

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