Flow-type battery cell

Abstract

The flow-type battery cell according to the present disclosure is characterized by comprising: a slurry containing a solid active material and an electrolyte solution; a negative electrode chamber to which the slurry is supplied; a positive electrode chamber for supplying air; and a liquid feeding control unit for changing the supply speed of the slurry.

Description

Technical Field

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

[0002] Conventionally, a battery cell has been disclosed.

[0003] For example, Metal-Air Batteries: Present and Perspectives discloses a battery using a zinc slurry uniformly dispersed with a binder. Summary of the invention

[0004] However, in the battery disclosed in Metal-Air Batteries: Present and Perspectives, if the weight ratio of zinc as an active material is increased, the viscosity increases, and the energy consumption of the pump due to pressure loss increases.

[0005] Therefore, the present disclosure has been made in view of the above-mentioned problems, and an object thereof is to provide a flow battery cell that suppresses energy consumption of a pump without degrading battery performance.

[0006] The flow battery cell of the present disclosure is characterized by comprising: a slurry containing a solid active material and an electrolyte; a negative electrode chamber supplied with the slurry; a positive electrode chamber supplied with air; and a liquid supply control unit for changing the supply speed of the slurry. Effects of the Invention

[0007] As described above, according to the present disclosure, it is possible to provide a flow battery cell that suppresses energy consumption of a pump without degrading battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic cross-sectional view of a flow battery cell according to the present disclosure. Figure 2 It is a graph showing the thickener concentration and solution viscosity (electrolyte). Figure 3 It is shown Figure 1 A schematic cross-sectional view of a modified example of a flow battery cell is shown. DETAILED DESCRIPTION

[0009] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0010] In addition, the present embodiment described below does not unduly limit the contents of the present disclosure as described in the claims, and not all of the structures described in this embodiment are necessary as the solution means of the present disclosure. In addition, the figure shows the X, Y, and Z axes, and in particular, the Z axis represents the gravity direction (height direction) of the liquid flow battery cell.

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

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

[0013] Figure 1 is a schematic cross-sectional view of a flow battery cell 100 according to the present disclosure. Figure 1 As shown, the liquid flow battery cell 100 according to the present disclosure includes a slurry 10, a negative electrode chamber 20, a negative electrode power 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 power plate 32, a separator 50, a sealing part 60, and a liquid supply control part 40. The liquid flow battery cell 100 according to the present disclosure is manufactured by stacking them.

[0014] The negative electrode chamber 20 is supplied with the slurry 10 described later. 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 take various shapes depending on the negative electrode 22 and the negative electrode flow path layer 23.

[0015] The negative electrode current conducting plate 21 is made of a conductive material that conducts electricity to the negative electrode 22. The shape of the negative electrode current conducting plate 21 is not limited.

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

[0017] The negative electrode channel layer 23 may be interposed between the separator 50 and the negative electrode 22 and / or the negative electrode current-carrying plate 21. In addition, the negative electrode 22 may also serve as the negative electrode channel layer 23.

[0018] The gasket 24 is interposed between the negative electrode channel layer 23 and the negative electrode 22 and / or the negative electrode current conducting 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 the positive electrode 31 and the positive electrode conducting plate 32. The positive electrode chamber 30 can adopt various shapes depending on the positive electrode conducting plate.

[0020] The positive electrode 31 is made of a conductive material, and has no particular limitation on shape.

[0021] The positive electrode current conducting plate 32 is made of a conductive material that conducts electricity to the positive electrode 31 .

[0022] In addition, when the flow battery cell 100 has a stack structure in which a plurality of cells are stacked, the negative electrode current conducting plates 21 and the positive electrode current conducting plates 32 of adjacent cells may be formed of 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 suppress 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 negative electrode flow path layer 23 and the positive electrode power supply portion 32. The sealing portion 60 may be provided in a frame shape, or may be arranged at the edge of the negative electrode flow path layer 23 and the positive electrode power supply portion 32. In this way, the slurry 10 is prevented from flowing to the positive electrode chamber 30 due to the pressure of the negative electrode flow path layer 23 and the positive electrode power supply portion 32 in the sealing portion 60.

[0025] The slurry 10 contains an electrolyte 12 and an active material. The active material includes a substance that dissolves in the electrolyte 12 and a solid active material 11 having electron conductivity that does not dissolve in the electrolyte 12 beyond the saturation solubility.

[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 constituting the metal species may be a metal consisting only of a metal as a main component, or may be an alloy of a metal as a main component and a secondary component. The metal species may be formed of any one of a metal and an oxide. Whether the metal species is a metal or an oxide depends on the extent of the discharge reaction or the charge reaction.

[0027] When the liquid flow battery cell 100 is shipped, the metal species may be any of a metal and an oxide. The oxidation state of the metal species may be uniform or non-uniform within the negative electrode active material. For example, when a discharge reaction or a charge reaction is performed from the surface toward 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 at the center of the negative electrode active material.

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

[0029] The average particle size of the metal species is several μm when it is an oxide in an oxidized state (such as ZnO), and is about tens of μm to 300 μm when it is a reduced state of a non-oxide (such as Zn). The average particle size 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 particle size D50 as the average particle size based on 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 contains 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, if the concentration of metal species such as zinc oxide and zinc is below the saturated solubility, the metal species dissolves, and if the concentration of metal species such as zinc oxide and zinc is higher than the saturated solubility, the metal species such as zinc oxide and zinc do not dissolve and exist as a solid active material 11. In addition, the solid active material particles can be judged by appearance. In the case of solid active material particles (exceeding saturation and not dissolved), the electrolyte is a suspension, and is white when the active material is zinc oxide. On the other hand, in the case of a saturated solution, it is transparent because it is dissolved. As an analysis, there is a method of measuring particle size distribution, using laser diffraction, dynamic light scattering, etc. In this embodiment, a suspension of metal species such as zinc oxide and zinc is used. In addition, the solid active material 11 has a larger capacitance per unit volume than the active material dissolved in the electrolyte. By supplying a small amount of slurry 10, the solid active material 11 required for the reaction can be excessively supplied to the negative electrode chamber 20, so the delivery of the slurry 10 can be temporarily stopped, which can reduce the power consumption of the pump.

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

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

[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 metal zinc as the solid active material becomes zincate ions by oxidation reaction and then becomes zinc oxide. In formula (2), it becomes hydroxide ions by oxygen reduction reaction.

[0036] The liquid supply control unit 40 changes the supply rate 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 rate of the slurry 10 may be controlled by the output of the pump or the like.

[0037] Thus, in the liquid flow battery cell 100 according to the present disclosure, by changing the supply rate of the slurry 10 by the liquid delivery control unit 40, it is possible to set a period in which the liquid delivery rate 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 delivery rate is reduced to allow the solid active material 11 to settle. Due to the reduction in the liquid delivery rate, the solid active material 11 settles, whereby particles of a plurality of solid active materials 11 contact each other to form an electron conduction path. In addition, by making it contact with the negative electrode 22, the reaction product of the negative electrode becomes larger. In this way, the power consumption of the pump can be reduced without reducing the battery performance.

[0038] In addition, if Figure 1 As shown, the flow battery cell 100 of the present embodiment further includes a slurry storage tank 70. The slurry storage tank 70 may also store the slurry 10 to be supplied to the negative electrode chamber 20. The slurry 10 may also be supplied from the slurry storage tank 70 to the negative electrode chamber 20.

[0039] The slurry storage tank 70 may include a stirrer 71 .

[0040] Figure 2: is a graph showing the concentration of thickener and the solution viscosity (electrolyte 12). Electrolyte 12 uses 7 mol / L KOH, 4 wt% ZnO as the active material, and Carbopol 690 (manufactured by Lubrizol) as the thickener. The viscosity can be measured by a viscometer. The viscometer can be measured, for example, by using a Viscotester VT-06 manufactured by RION Corporation using any one of rotors 1 to 3.

[0041] The slurry 10 preferably contains a thickener. Since the specific gravity difference 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. Figure 2 As shown, the viscosity of the solution increases after the thickener is added. That is, by including the thickener, the sedimentation rate of the solid active material 11 can be reduced, and the solid active material 11 can be uniformly dispersed in the slurry 10 even after a period of time. In addition, the slurry 10 may also contain a gelling agent.

[0042] The concentration of the thickener in the slurry 10 is preferably 0.75wt% or more and less than 3wt%, and more preferably 1wt% or more and less than 2wt%. If it is less than 0.75wt%, the sedimentation rate of the solid active material 11 is too fast, and the flow rate needs to be increased to transport the solid active material 11, which increases the power consumption of the pump. In addition, if it is more than 3wt%, the viscosity is too high, the pressure loss during liquid delivery increases, and the power consumption of the pump increases.

[0043] The viscosity of the electrolyte 12 is preferably 10 mPa·s to 300 mPa·s. If it is less than 10 mPa·s, the sedimentation rate of the solid active material 11 is too fast, and the flow rate needs to be increased to transport the solid active material 11, which increases the power consumption of the pump. In addition, if it is greater than 300 mPa·s, the viscosity becomes higher, the pressure loss during slurry delivery becomes larger, and thus the power consumption of the pump becomes larger.

[0044] The viscosity of the slurry 10 is preferably 100 mPa·s to 3000 mPa·s. When the viscosity is too low, the sedimentation rate of the solid active material 11 is fast. It is necessary to increase the frequency of the increase in the flow rate of the solid active material 11 used to transport the sedimentation, and the power consumption of the pump tends to increase. On the other hand, when the viscosity is too high, the pressure loss when transporting the slurry of the solid active material 11 becomes large, so the power consumption of the pump becomes large. In addition, since the solid active material 11 does not settle and remains in a dispersed state, the negative electrode 22 cannot contact the solid active material 11, and the particles of the solid active material 11 after contact cannot continuously contact the particles of other solid active materials 11 (the number of particles of active material conducting with the negative electrode 22 decreases, and the formation of the electron conduction path decreases), and the electron conduction path from the solid active material 11 to the negative electrode 22 cannot be formed, and the utilization efficiency of the active material is reduced. Therefore, if it is set to the above range, it is possible to suppress the sedimentation rate of the solid active material 11 from being too fast, suppress the power consumption of the pump, suppress the pressure loss during liquid delivery, and improve the utilization efficiency of the active material.

[0045] The average particle size of the metal species is as described above, but the average particle size of the solid active material 11 in a reduced state that is not an oxide is preferably 30 μm to 300 μm. If it is less than 30 μm, it is difficult for the particles of the solid active material 11 to contact each other and it is difficult to form an electron conduction path. If it is greater than 300 μm, the sedimentation rate of the solid active material 11 is fast, and in order to transport the settled particles of the solid active material 11, it is necessary to increase the flow rate, and the power consumption of the pump increases.

[0046] Figure 3 It is shown Figure 1 1 is a schematic cross-sectional view of a modified example of the flow battery cell 100 shown in FIG. Figure 3 As shown in the flow type battery cell 110, the negative electrode 22 is arranged in the gravity downward direction relative to the positive electrode chamber 30. In this way, since the solid active material 11 is precipitated on the negative electrode 22, an electron conduction path from the solid active material 11 to the negative electrode 22 can be effectively formed. Therefore, the electric capacity can be further increased.

[0047] The liquid delivery control unit 40 preferably reduces the supply speed of the slurry 10 during power generation, or stops the supply. In this way, the power consumption of the pump can be suppressed. When the supply speed of the slurry 10 is reduced, since the flow of the slurry is maintained, the solid active material 11 in the slurry 10 can be suppressed from being fixed and accumulated in the negative electrode chamber. When the supply speed of the slurry 10 is stopped, the power consumption of the pump can be suppressed to 0.

[0048] In the liquid feeding control unit 40, during power generation, it is preferred that the supply speed reduction time of the slurry 10 is longer than the supply time of the slurry 10, and it is more preferred that the supply stop time of the slurry 10 is longer than the supply time of the slurry 10. In this way, the accumulation of the solid active material 11 can be 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 speed of the slurry 10 is reduced or stopped, the power consumption of the pump can be suppressed.

[0049] The liquid delivery control unit 40 preferably periodically changes the supply speed during power generation. In this way, the slurry 10 can be efficiently transported to the negative electrode chamber 20, so that power generation can be efficiently performed. In addition, the liquid delivery control unit 40 can also periodically change the presence or absence of supply during power generation (supply / stop). The so-called periodicity refers to the change of the supply speed and the presence or absence of supply multiple times at arbitrary time intervals.

[0050] Preferably, the mixer 71 is operated periodically.

[0051] Furthermore, the operation of the agitator 71 is preferably synchronized with the liquid supply control unit 40. For example, when the liquid supply control unit 40 supplies the slurry 10, the agitator 71 operates. On the other hand, when the liquid supply control unit 40 stops the supply of the slurry 10, the agitator 71 stops. In addition, the agitation of the agitator 71 may not be performed simultaneously with the infusion, and the operation may be performed at an arbitrary time offset from the switching of the infusion. In addition, when the liquid supply control unit 40 periodically changes the presence or absence of supply (supply / stop), the agitator 71 also periodically performs the presence or absence of agitation corresponding thereto.

[0052] The sedimentation velocity of the solid active material 11 follows the Stokes equation described below. vs=Dp 2 (ρ p -ρ f )g / 18η vs: particle terminal velocity Dp: particle size ρp: particle density ρf: fluid density g: acceleration due to gravity η: fluid viscosity

[0053] When the distance from the separator 50 to the negative electrode 22 is set to L (cm) and the change period of the supply rate is set to T (s), it is preferred to satisfy T>L×35. The sedimentation rate of the solid active material 11 is determined by the particle size, density, and viscosity according to the Stokes equation. Since an electron conduction path with the negative electrode 22 is formed by the sedimentation of the solid active material 11, if the period of change of the supply rate is small relative to the sedimentation rate and the sedimentation distance, that is, the distance from the separator 50 to the negative electrode 22, it is difficult to form a sufficient electron conduction path, and the battery performance is reduced. The particle size in the Stokes equation is set to 300μm, the fluid viscosity is set to 10mPa·s, and the fluid density is set to 1.34g / cm 3 The particle density is set to 7.14 g / cm 3 , the calculated sedimentation velocity vs is 2.842×10 ^ (-2) m / s. The supply speed variation cycle refers to a cycle of "fast / slow" supply speed of the slurry 10 or a cycle of "presence / absence" of supply. It suffices if the supply speed is slightly different.

[0054] For example, when the distance L from the separator 50 to the negative electrode 22 is 1 cm, when the cycle T of the change in the supply speed is 30 seconds, the average discharge voltage is low, whereas when the cycle T is 60 seconds, the average discharge voltage becomes high. Also, when the distance L is 0.5 cm, when the cycle T is 10 seconds, the average discharge voltage is low, whereas when the cycle T is 20 seconds, the average discharge voltage becomes high.

[0055] When the solid active material 11 is zinc, the volume of the negative electrode chamber 20 is S (cm 3 ), the density of the slurry 10 is set to ρ (g / cm 3 ), when the discharge current is set to I (A) and the weight ratio of zinc in the slurry 10 is set to X (wt%), it is preferred to satisfy S×ρ×(X / 100) / 65.4>I×T / (96500×2). That is, this means that the amount of zinc consumed only during the discharge of period T is less than the amount of all 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 during the discharge of period T with the current I, there is a tendency that discharge cannot occur due to the complete absence of dischargeable zinc, so it is preferred to satisfy the above formula.

[0056] In addition, in (S×ρ×(X / 100) / 65.4)×M>I×T / (96500×2), it is more preferably satisfied that 1 / 10 < M < 1 / 2, and further preferably satisfied that 1 / 5 < M < 1 / 3. When M is less than 1 / 10, the cycle T becomes short and the power consumption of the pump becomes large. When M is 1 / 2 or more, zinc oxide precipitated in the slurry 10 present in the negative electrode chamber 20 becomes a resistance, and the discharge voltage may decrease. By setting it within the above range, it is possible to suppress the power consumption of the pump while preventing the deterioration of battery performance.

[0057] When the ratio of the flow time for reducing the slurry supply speed or the time for stopping the flow (supply) of the cycle with respect to the change in the slurry supply speed is set as α, it is preferably satisfied that 0.4 < α < 0.97. 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, according to the flow-type battery cells 100 and 110 of the present disclosure, the capacitance can be increased and the energy consumption of the pump can be suppressed.

[0059] In addition, as described above, the respective embodiments and examples of the present disclosure have been described in detail, but those skilled in the art can easily understand that various modifications can be made without substantially departing from the new matters and effects of the present disclosure. Therefore, all such modified examples are included within the scope of the present disclosure.

[0060] For example, in the specification or the drawings, a term that is described at least once together with a different term that is more general or synonymous can be replaced with that different term anywhere in the specification or the drawings. In addition, the configuration and operation of the flow-type battery cell are not limited to the configuration and operation described in the respective embodiments and examples of the present disclosure, and various modifications can be implemented.

Claims

1. A liquid flow battery cell, characterized in that: include: a slurry containing a solid active material and an electrolyte; a cathode chamber supplied with the slurry; a cathode chamber, which is supplied with air; as well as A liquid feeding control unit is used to change the feeding speed of the slurry.

2. The flow battery cell according to claim 1, characterized in that: The slurry includes a viscosity enhancing agent.

3. The liquid flow battery cell according to claim 1 or 2, characterized in that: The viscosity of the electrolyte is 10 mPa·s to 300 mPa·s.

4. The liquid flow battery cell according to claim 1 or 2, characterized in that: The viscosity of the slurry is 100 mPa·s to 3000 mPa·s.

5. The liquid flow battery cell according to claim 1 or 2, characterized in that: The average particle size of the solid active material is 30 μm to 300 μm.

6. The liquid flow battery cell according to claim 1 or 2, characterized in that: Also includes the negative electrode, The negative electrode is arranged in a downward direction under gravity with respect to the positive electrode chamber.

7. The liquid flow battery cell according to claim 1 or 2, characterized in that: The liquid supply control unit reduces the supply rate of the slurry or stops the supply during power generation.

8. The flow battery cell according to claim 7, characterized in that: The liquid supply control unit stops supply of the slurry during power generation.

9. The liquid flow battery cell according to claim 7, characterized in that: The liquid supply control unit reduces the supply rate of the slurry for a long period of time during power generation.

10. The liquid flow battery cell according to claim 8, characterized in that: The liquid supply control unit performs control during power generation so that a supply stop time of the slurry is longer than a supply time of the slurry.

11. The liquid flow battery cell according to claim 1 or 2, characterized in that: The liquid supply control unit periodically changes the supply rate during power generation.

12. The liquid flow battery cell according to claim 1 or 2, characterized in that: The concentration of the solid active material in the slurry is 5 wt % to 50 wt %.

13. The liquid flow battery cell according to claim 1 or 2, characterized in that: Also includes a slurry storage tank, The slurry storage tank includes a stirrer.

14. The liquid flow battery cell according to claim 13, characterized in that: The mixer is operated periodically.

15. The liquid flow battery cell according to claim 13, characterized in that: The operation of the agitator is synchronized with the liquid delivery control unit.

16. The flow battery cell according to claim 11, characterized in that: Also includes a negative electrode and a separator separating the negative electrode chamber from the positive electrode chamber, When the distance from the separator to the negative electrode is L (cm) and the change period of the supply speed is T (s), Satisfies T>L×35.

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

18. The liquid flow battery cell according to claim 11, characterized in that: When the ratio of the flow time during which the slurry supply speed is reduced or the flow is stopped is α, Satisfies 0.4<α<0.97.

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