Method for removing zinc dendrites and recovering short in zinc-bromine battery

Abstract

The present invention relates to a method for removing zinc dendrites in a zinc-bromine battery. The method for removing zinc dendrites in a zinc-bromine battery according to one embodiment of the present invention may comprise: a step of preparing a zinc-bromine battery in which zinc dendrites are formed by usage or charging; and a step of reversely charging the zinc-bromine battery.

Description

Method for Removing Zinc Dendrites and Short-Circuit Repair in Zinc-Bromine Batteries

[0001] The present invention relates to a method for removing zinc dendrites and recovering a short circuit in a zinc-bromine battery, and more particularly, to a method for removing zinc dendrites or recovering a short circuited zinc-bromine battery by a reverse charging method.

[0002] Globally, there's a growing demand for new energy sources like solar and wind power to address global warming. However, to compensate for the intermittent nature of renewable energy sources, which generate power intermittently under specific conditions, secondary batteries, which have the ability to store electricity, are attracting significant attention.

[0003]

[0004] Among various secondary batteries, lithium-ion batteries are widely used due to their high energy density (over 250 Wh / kg & 650 Wh / L), voltage (over 3.2 V), and excellent cycle life (over 3,000 cycles). Furthermore, their advanced manufacturing process has made them easy to commercialize. However, lithium-ion batteries frequently cause fires in ESS, electric vehicles, and small devices due to the use of flammable materials. This is because the temperature rise caused by a short-circuit in the battery can ignite the flammable organic electrolyte. Therefore, to transform the global ecosystem centered on renewable energy-based power use, next-generation secondary battery technology with high stability and high performance is required.

[0005]

[0006] Accordingly, all-solid-state lithium metal batteries and supercapacitors are attracting attention. However, the sulfide-based all-solid-state materials, which are all-solid-state batteries being developed mainly by global multinational corporations, are expensive, with a price tag of approximately 700,000 won / kg as of 2022, which is more than 5.8 times that of existing lithium-ion batteries (120,000 won / kg), requiring a considerable amount of time and development time for commercialization. In particular, despite the long-term R&D period of all-solid-state battery technology of over 15 years since the establishment of the Next-Generation Battery Research Institute in 2008 by Toyota, Japan, a leader in hybrid technology since the 1990s, the commercialization of products remains uncertain. Furthermore, supercapacitors have a clear limitation in that their energy storage capacity per unit mass (16 Wh / kg) is significantly lower than that of lithium-ion batteries (250 Wh / kg). As such, existing energy storage technologies have only biased special features, making it difficult to expect them to play a key role in the future power ecosystem.

[0007]

[0008] To overcome the aforementioned challenges, energy storage systems using aqueous electrolytes have recently attracted significant attention from both academia and industry. Commercialized aqueous secondary batteries include lead-acid batteries, vanadium flow batteries, and zinc-air batteries. Together with lithium-ion batteries, they account for over 50% of the global energy storage market.

[0009]

[0010] Aqueous secondary batteries possess the greatest advantage over organic lithium-ion batteries, primarily due to their high safety and non-incendive nature. Conventional organic lithium batteries, when applied to energy storage systems (ESS) and electric vehicles, require additional technological solutions, such as battery management systems (BMS) and battery protection units (BPUs), to alert and prevent fires. This is a key factor driving up the system's price. However, non-incendive aqueous secondary batteries require only lower-spec, lower-cost BMS technology, resulting in improved price competitiveness for ESS and electric vehicles. Furthermore, conventional lithium-ion batteries require a manufacturing step where all battery cells are inspected via X-ray prior to shipment to screen for factors that can cause internal short circuits. In contrast, aqueous secondary batteries, due to their non-incendive nature, eliminate the need for X-ray inspection. Therefore, due to these advantages, non-incendive aqueous secondary batteries are attracting attention as a key technology that can improve product prices and consumer safety.

[0011]

[0012] Furthermore, lithium-ion batteries are expected to grow at an average annual rate of 32% through 2030, centered on batteries for electric vehicles. However, key materials are monopolized by some countries or are limited resources, resulting in oversupply in some national markets and serious global oversupply or shortages. In particular, the price of lithium for lithium-ion batteries has risen sharply by 457%, from KRW 10,000 / kg in 2021 to KRW 57,000 / kg in 2022, driving up the price of lithium-ion batteries. Consequently, research is actively underway globally to develop alternatives to lithium, such as bromine (KRW 4,000 / kg) and zinc (KRW 5,000 / kg), which are abundant resources, have a smooth supply chain, and are inexpensive.

[0013] Aqueous secondary batteries utilizing zinc and bromine rather than lithium are price competitive, boast a high rated voltage of 1.7 V, and an energy density of 85 Wh / kg, surpassing even leading aqueous secondary battery technologies such as lead-acid batteries (40 Wh / kg) and vanadium flow batteries (30 Wh / kg). However, aqueous zinc-bromine batteries still have issues that require improvement, such as short circuits caused by zinc dendrites on the cathode and subsequent performance degradation.

[0014] The present invention relates to a method for removing zinc dendrites and recovering a short circuit in a zinc-bromine battery, and more specifically, to provide a method for removing zinc dendrites or recovering a short circuited zinc-bromine battery by a reverse charging method.

[0015] One embodiment of the present invention provides a method for removing zinc dendrite from a zinc-bromine battery, comprising the steps of: providing a zinc bromine battery in which zinc dendrite is formed by use or charging; and reversely charging the zinc bromine battery.

[0016] A step of resting the zinc bromine battery may be additionally included after the above reverse charging step.

[0017] A step of reverse discharging the zinc bromine battery may be additionally included after the above reverse charging step.

[0018] In the above zinc bromine battery preparation step, the zinc bromine battery may have a short circuit during charging.

[0019] The zinc bromine battery may include first and second electrodes arranged opposite to each other, a separator arranged between the first and second electrodes, and an electrolyte.

[0020] A current collector may be placed on each of the first and second electrodes.

[0021] The zinc bromine battery may include first and second current collectors arranged opposite to each other, a first electrode formed on the first current collector, a separator arranged between the first electrode and the second current collector, and an electrolyte.

[0022] According to one embodiment of the present invention, the first electrode or the second electrode may be manufactured by a dry process.

[0023] The above electrolyte may include an aqueous solvent and a zinc / bromine redox couple.

[0024] According to one embodiment of the present invention, zinc dendrites generated during use or charging of a zinc bromine battery can be removed through a step of reverse charging the zinc bromine battery. Furthermore, if a short circuit occurs due to the zinc dendrites, the short circuit can be repaired by removing the zinc dendrites.

[0025] When charging a zinc-bromine battery, zinc is produced at the negative electrode and a bromine compound is produced at the positive electrode. However, when (+) and (-) are reversed and charged, zinc dendrites may be produced at the positive electrode and bromine compounds may be produced at the negative electrode. The bromine compounds produced at the negative electrode can also be absorbed by the separator. The zinc dendrites (Zn(s)) present at the negative electrode can be removed through self-discharge by the bromine compounds present in the negative electrode and the separator.

[0026] According to one embodiment of the present invention, when only a current collector is used without using an anode, the separator, not the anode, can absorb all of the bromine compounds, and thus zinc dendrites (Zn(s)) present in the separator can be more effectively removed.

[0027] FIG. 1 is a cross-sectional view schematically showing a zinc-bromine battery cell according to one embodiment of the present invention.

[0028] FIG. 2 is a graph showing the charge / discharge cycle of a zinc-bromine battery that has undergone reverse charging according to one embodiment of the present invention.

[0029] FIG. 3 is a graph of time-voltage and current of a zinc-bromine battery that has undergone reverse charging according to one embodiment of the present invention.

[0030] Figure 4 is a graph showing the charge / discharge cycle of a zinc-bromine battery that has not been reversely charged.

[0031] Hereinafter, embodiments and examples of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments and examples described herein.

[0032]

[0033] The terminology used in this application is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, steps, operations, components, parts, or combinations thereof.

[0034]

[0035] Additionally, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by those of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0036]

[0037] The present invention relates to a method for removing zinc dendrites and recovering a short circuit in a zinc-bromine battery, and more particularly, to a method for removing zinc dendrites or recovering a short circuited zinc-bromine battery by a reverse charging method.

[0038] A method for removing zinc dendrites and recovering a short circuit of a zinc-bromine battery according to one embodiment of the present invention may include the steps of: preparing a zinc-bromine battery in which zinc dendrites are formed by use or charging; and reverse-charging the zinc-bromine battery.

[0039] According to one embodiment of the present invention, zinc dendrite can be removed from a zinc bromine battery in which zinc dendrite has formed or a short circuit has occurred due to the zinc dendrite during use or charging. Accordingly, performance degradation of the zinc bromine battery can be prevented, and if a short circuit occurs, the short circuit can be repaired.

[0040]

[0041] Figure 1 illustrates a unit cell of a zinc-bromine battery, through which a method for removing zinc dendrite from a zinc-bromine battery is specifically explained.

[0042] According to one embodiment of the present invention, a zinc-bromine battery can be implemented by stacking one or more unit cells, and the zinc-bromine battery can be a battery in the shape of a pouch, square, cylindrical, etc. by stacking the unit cells.

[0043]

[0044] Referring to FIG. 1, a zinc-bromine battery cell may include first and second electrodes (221, 222), a separator (240) disposed between the first and second electrodes, and an electrolyte.

[0045] The first electrode and the second electrode (221, 222) may have opposite polarities, for example, the first electrode (221) may function as an anode and the second electrode (222) may function as a cathode. The first electrode and the second electrode (221, 222) may include a carbon body, a conductive material, and a binder.

[0046] According to one embodiment of the present invention, the first electrode and the second electrode (221, 222) can be manufactured by a dry process. The dry process does not use a solvent when manufacturing the electrode, and is not limited thereto. For example, an electrode sheet can be manufactured by dry mixing and milling an electrode powder in which a carbon body, a conductive material, and a binder are mixed, and then rolling the milled electrode powder.

[0047] The first and second electrodes manufactured by the dry process can very well absorb the bromine compound (liquid) generated during charging.

[0048]

[0049] Typically, aqueous zinc-bromine batteries can develop zinc dendrites on the cathode with repeated use and charging. Assuming that 100% Zn and 100% Br2 are generated during charging, Br2 easily evaporates and vaporizes, leaving 95% of the Br2 remaining in the cell during discharge. Therefore, only 5% of the zinc can remain after a complete discharge. As charging and discharging continue, the zinc that is not available for discharge continues to increase. These zinc dendrites can degrade battery performance and, if they come into contact with the cathode, can cause a short circuit. However, zinc dendrites can be somewhat eliminated through self-discharge.

[0050] Self-discharging is the process of discharging a bromine compound (Br2, Br) which is an active non-metallic element. 3- , Br 5- It can be defined as a reaction between zinc (Zn) and bromine to produce zinc bromide (ZnBr2). This is a type of oxidation-reduction reaction, in which zinc is oxidized and bromine is reduced, and can be expressed as follows.

[0051] Zn(s) + Br2(g) ZnBr2(s) [white]

[0052]

[0053] Zinc reacts with monovalent bromine ion (Br - ) has higher chemical activity than the monovalent bromine ion (Br - ) does not corrode zinc metal (Zn(s)), but Br compounds (Br2, Br 3- , Br 5- etc.) can corrode zinc metal (Zn(s)). In the case of aqueous zinc bromine batteries, bromine compounds (Br2, Br) are formed at the positive electrode during charging. 3- , Br 5-(etc.) are generated, and when the zinc dendrites (Zn(s)) generated during charging come into contact with the anode, the short circuit can be resolved by self-discharge due to the bromine compound generated at the anode, allowing the cell to restart. In other words, even if a cell that has been short-circuited by zinc dendrites during charging is left alone, the cell can be revived by self-discharge. However, while zinc dendrites that come into contact with the anode can be removed through self-discharge, zinc dendrites that have penetrated the separator and exist within the separator may be difficult to self-discharge. This is because when the anode absorbs most of the bromine compound generated, the amount of bromine compound present in the separator is extremely small. In addition, zinc dendrites that are not completely removed can cause continuous zinc dendrite growth, and even if they are recovered once, there is a high possibility that a short circuit will occur again in the future.

[0054]

[0055] However, according to one embodiment of the present invention, zinc dendrites can be removed through the step of reverse charging the zinc bromine battery.

[0056] When charging a zinc-bromine battery, zinc is produced at the negative electrode and a bromine compound is produced at the positive electrode. However, when (+) and (-) are reversed and charged, zinc dendrites may be produced at the positive electrode and bromine compounds may be produced at the negative electrode. The bromine compounds produced at the negative electrode can also be absorbed by the separator. The zinc dendrites (Zn(s)) present at the negative electrode can be removed through self-discharge by the bromine compounds present in the negative electrode and the separator.

[0057]

[0058] Reverse charging lithium-ion batteries can reverse chemical reactions within the battery, increasing the risk of overheating, explosion, or fire. Furthermore, the battery's internal structure and chemicals can be damaged, reducing its lifespan, degrading its performance, or even causing it to break.

[0059] However, in the case of zinc-bromine batteries, there is 0% risk of explosion even if reverse charging is performed, the battery is not damaged, and there is no reduction in lifespan.

[0060]

[0061] According to one embodiment of the present invention, after sufficient reverse charging has been performed, a resting step may be additionally performed. In the present invention, the resting step may refer to a state in which reverse charging and reverse discharging are not performed.

[0062] Through the above resting step, zinc dendrites (Zn(s)) can be sufficiently removed. The rate at which Zn is corroded by Br2 increases as the temperature increases, the pH decreases, and the salt (Cl) - The higher the concentration of (etc.), the faster it can be.

[0063]

[0064] According to one embodiment of the present invention, in order to confirm whether zinc dendrites (Zn(s)) have been sufficiently removed, the voltage change according to the charging time can be measured or the resistance can be measured. If the voltage in the voltage-time graph increases steadily above 1.6 V during charging, it can be considered that the short circuit has been resolved and the zinc dendrites have been sufficiently removed. In addition, in the case of resistance measurement, if the resistance is large before the short circuit occurs (for example, at the level of 10 kΩ), and the resistance that has decreased due to the short circuit occurrence (for example, at the level of 0.1 Ω) increases significantly again (for example, at the level of 10 kΩ), it can be considered that the short circuit caused by the dendrites has been resolved.

[0065]

[0066] According to one embodiment of the present invention, a step of reverse-discharging the zinc-bromine battery may be additionally included after the reverse-charging step. By reverse-discharging, zinc present in the positive electrode that is not fully used due to self-discharge and bromine compounds present in the negative electrode can be removed.

[0067]

[0068] According to one embodiment of the present invention, the first and second electrodes (221, 222) may be formed on the first and second current collectors (211, 212), respectively. The first and second current collectors (211, 212) may be formed of a metal, a carbon body, or the like. Since the metal causes a corrosion reaction in an aqueous electrolyte, titanium (Ti), titanium carbide, stainless steel (SUS), nickel (Ni), or the like may be used. The carbon body is not limited thereto, but may be, for example, graphite foil, carbon cloth, carbon paper, or a mixture thereof. When a carbon body, titanium, or titanium carbide is used as the first and second current collectors (211, 212), the electrode used as the negative electrode (222) may not be used (not shown). In this case, the second current collector (212) may function as the negative electrode.

[0069] In this case, when no cathode is used (anode free), the separator, not the cathode, can absorb all of the bromine compounds, and in this case, zinc dendrites (Zn(s)) present in the separator can be removed more effectively.

[0070]

[0071] According to one embodiment of the present invention, the first electrode and the second electrode (221, 222) may be formed with a thickness of 10 to 30,000 μm. Specifically, the cathode may be formed with a thickness of 10 to 100 μm, and the anode may be formed with a thickness of 150 to 170 μm. In addition, it is preferable that the specific surface area of ​​the electrode be formed large, and is not limited thereto, for example, 1,000 to 3,000 m 2 / g can be formed. The specific surface area may vary depending on the properties of the carbon material used in the electrode mixture.

[0072]

[0073] According to one embodiment of the present invention, the carbon material used in the electrode is not limited thereto, and for example, activated carbon, graphite, hard carbon, or porous carbon material can be used. The porous carbon material is not limited thereto, but carbon felt, carbon cloth, or carbon paper, etc. can be used. Specifically, activated carbon can be used, and activated carbon having an average particle size of 1 to 10 ㎛ can be used. Specifically, activated carbon having an average particle size of 5 to 6.5 ㎛ can be used. Activated carbon having a porosity of 80% or more can be used, and BET can be used. In addition, activated carbon having a tap density of 0.35 to 0.50 g / cc can be used.

[0074] The above carbon body can be used in an amount of 70 to 90 parts by weight. If the content is less than 70 parts by weight, the reaction area of ​​the electrode may be reduced, which may deteriorate the performance of the battery. If the content exceeds 90 parts by weight, the content of the conductive material or binder may be insufficient, which may deteriorate the performance of the battery and cause problems in the process.

[0075]

[0076] The conductive material is not limited thereto, but may include, for example, carbon-based conductive materials such as carbon black, carbon fiber, carbon nanotubes, or graphite. The carbon black is not limited thereto, but may include, for example, acetylene black, Ketjen black, Super P, channel black, furnace black, lamp black, or thermal black. The graphite may be natural graphite or artificial graphite.

[0077] The above-mentioned conductive agent may be used in an amount of 5 to 20 parts by weight. If the content is less than 5 parts by weight, the electrical conductivity of the electrode may be low, which may deteriorate the performance of the battery. If the content exceeds 20 parts by weight, the reaction area of ​​the electrode may be reduced, which may deteriorate the performance.

[0078]

[0079] The binder is not limited thereto, but may include, for example, carboxymethyl cellulose, styrene butadiene rubber, polyvinylidene fluoride, or polytetrafluoroethylene. According to one embodiment of the present invention, the binder may have a particle size of 500 to 700 μm. By using a binder having the above particle size, the fiberization effect of the polymer can be enhanced in the milling process for forming an electrode.

[0080] The above binder may be used in an amount of 5 to 20 parts by weight. If the content is less than 5 parts by weight, there is a risk that it may not function as a binder between the active material and the conductive material or as a binder with the current collector. If the content exceeds 20 parts by weight, there is a risk that it may actually deteriorate the performance of the battery.

[0081]

[0082] According to one embodiment of the present invention, the separator (240) performs the main function of preventing internal short circuit during charging or discharging and containing an electrolyte.

[0083] The material of the above separation membrane (240) is not particularly limited, and may be, for example, a polyolefin film containing polyethylene or polypropylene, a fiber nonwoven fabric containing polyvinyl chloride, cellulose, polyester or polypropylene, and specifically, cellulose.

[0084]

[0085] According to one embodiment of the present invention, the electrolyte may include an aqueous solvent (water) and a zinc / bromine redox couple.

[0086] Additionally, the electrolyte may include bromic acid, an acidic substance other than bromic acid, and a bromine complexing agent. Additionally, a supporting electrolyte and other additives may be additionally included to improve the conductivity of the electrolyte.

[0087] According to one embodiment of the present invention, the electrolyte may be an acidic aqueous electrolyte, and the pH may be 2 to 4 or less.

[0088]

[0089] The above bromine complexing agent may include quaternary ammonium bromide. Examples thereof include, but are not limited to, pyridinium bromide having 1 or more substituted alkyl groups having 1 to 10 carbon atoms, imidazolium bromide having 1 or more substituted alkyl groups having 1 to 10 carbon atoms, tetraethylammonium bromide (TEA), tetrabutylammonium bromide (TBA), tetrapropylammonium bromide, 1-Ethyl-2-Methylpyridinium bromide, 4-Ethyl-4-Methylmorpholinium bromide, (3-chloro-2-hydroxypropyl)trimethylammonium bromide. ((3-Chloro-2-hydroxypropyl) trimethylammonium bromide), 1-Ethyl-1-methylpyrrolidinium bromide, CHA (3-chloro-2-hydroxypropyltrimethyl ammonium chloride), 18-Crown-6, 15-Crown-5, Cetyltrimethylammonium bromide, etc. can be used.

[0090] Acidic substances other than the above-mentioned hydrobromic acid (HBr) are not limited thereto, but for example, strong acids having a pH of 2.0 or lower, or -1.0 to 2.0, specifically, hydrochloric acid, nitric acid, sulfuric acid, hydroiodic acid, acetic acid, citric acid, potassium dihydrogen citrate, or mixtures of two or more thereof may be used. In addition, other additives may include NH4Cl, NH4Br, NH4SO4, CsCl, CsBr, CsSO4, Rb4Cl, Rb4Br, RbSO4ZnCl2, Na2SO4, NaCl, KCl, KBr, CaBr, CaCl2.

[0091]

[0092] Hereinafter, the present invention will be described in more detail through examples according to one embodiment of the present invention, but these examples do not limit the scope of the present invention.

[0093]

[0094] [Example]

[0095] Manufacturing example

[0096] A zinc bromine battery cell was manufactured using a 25 ㎛ thick graphite foil as a negative electrode collector (anode-free), an electrode (thickness 160 ㎛) manufactured by a dry process by mixing 80 (activated carbon YP-50F): 10 (conductive material): 10 (binder) as a positive electrode collector, and a cellulose separator (180 ㎛) as a positive electrode collector. An aqueous electrolyte containing 4.5 M ZnBr2 and 0.5 M TEA (2 mL) was used as the electrolyte, and the cell fastening pressure was 2 kgf·cm.

[0097]

[0098] [evaluation]

[0099] 1) Example

[0100] At room temperature of 25℃, the above cell is charged at a current density of 10mA / cm 2 Charge for 15 minutes, rest for 1 minute after charging, discharge at a current density of -10mA / cm 2The cut-off voltage was 0 V, and a rest period (REST) ​​of 1 minute was performed after discharge.

[0101] When a short circuit occurred due to repeated charging and discharging, reverse charging was performed (connecting the + and - terminals interchangeably). The reverse charging was performed for 210 to 220 cycles, a total of 11 cycles. The reverse charging condition was a current density of 10 mA / cm 2 15 minutes, then 15 minutes of rest after reverse charging, reverse discharge at a current density of -10mA / cm 2 , cut-off voltage 0V, and a rest period (REST) ​​of 1 minute was performed after discharge.

[0102] After short-circuit recovery, the voltage was changed back to +, - and charging and discharging were performed (221 to 1500 cycles). At this time, charging was performed at a current density of 10 mA / cm 2 Charge for 15 minutes, rest for 1 minute after charging, discharge at a current density of -10mA / cm 2 The cut-off voltage was 0 V, and a rest period (REST) ​​of 1 minute was performed after discharge. The results are shown in Fig. 2.

[0103] Figure 3 is a graph of time-voltage and current (cycles 205 to 222), showing that the voltage decreases rather than increases during charging due to a short circuit caused by zinc dendrites. After the short circuit occurred, reverse charging and reverse discharging were performed at cycles 210 to 220. The reverse charging was performed at a current density of 10 mA / cm. 2 , proceed for 15 minutes, rest for 15 minutes, reverse discharge cut-off 0 V, current density -10 mA / cm 2 , rest was conducted for 0 minutes

[0104]

[0105] 2) Comparative example

[0106] At room temperature of 25℃, the above cell is charged at a current density of 10mA / cm 2Charge for 15 minutes, rest for 1 minute after charging, discharge at a current density of -10mA / cm 2 The cut-off voltage was 0 V, and a rest period (REST) ​​of 1 minute was performed after discharge. The results are shown in Fig. 4.

[0107] Referring to Figure 4, frequent short circuits occurred during charging and discharging because reverse charging was not performed. Short circuits caused by zinc dendrites occurred three times up to 1500 cycles.

[0108]

[0109] In contrast, referring to FIGS. 2 and 3, it can be confirmed that after the short circuit occurred, reverse charging was performed and the short circuit due to zinc dendrite no longer occurred. Self-discharge was occurring due to the bromine compound generated during the 11th cycle of reverse charging. In the last 11th cycle of reverse charging, the zinc dendrite was removed by self-discharge during the rest (REST) ​​stage after reverse charging and no longer occurred.

[0110] Also, the reason why the charging voltage did not continuously increase in the last 11th cycle of reverse charging is that, as an anode-free cell, there is no electrode to absorb the bromine compound during reverse charging, so the bromine compound is an active material, bromine ion (Br), at the current collector (acting as a cathode)-separator interface. - ) hinders the diffusion of the active material (Br) at the interface between the current collector (acting as the negative electrode) and the separator. - ) is insufficient, so water decomposition occurs relatively frequently and the voltage decreases.

[0111]

[0112] The above description is merely an example of the technical idea of ​​the present embodiment, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical idea of ​​the present embodiment, but rather to explain it, and the scope of the technical idea of ​​the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment should be interpreted by the claims below, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of rights of the present embodiment.

Claims

1. A step of preparing a zinc bromine battery in which zinc dentrite is formed by use or charging; and A method for removing zinc dentrite from a zinc-bromine battery, comprising the step of reverse charging the zinc-bromine battery.

2. In paragraph 1, A method for removing zinc dentrite from a zinc-bromine battery, further comprising a step of resting the zinc-bromine battery after the reverse charging step.

3. In paragraph 1, A method for removing zinc dentrite from a zinc-bromine battery, further comprising a step of reverse-discharging the zinc-bromine battery after the above-mentioned reverse-charging step.

4. In paragraph 1, A method for removing zinc dentrite from a zinc-bromine battery in which a short circuit occurs during charging in the zinc-bromine battery preparation step.

5. In paragraph 1, A method for removing zinc dendrite from a zinc-bromine battery, the zinc-bromine battery comprising first and second electrodes arranged opposite to each other, a separator arranged between the first and second electrodes, and an electrolyte.

6. In paragraph 5, A method for removing zinc dentrite from a zinc-bromine battery, wherein a current collector is disposed on each of the first and second electrodes.

7. In paragraph 1, A method for removing zinc dendrite from a zinc-bromine battery, the zinc-bromine battery comprising first and second current collectors arranged opposite to each other, a first electrode formed on the first current collector, a separator arranged between the first electrode and the second current collector, and an electrolyte.

8. In paragraph 5 or paragraph 7, A method for removing zinc dendrite from a zinc-bromine battery, wherein the first electrode or the second electrode is manufactured by a dry process.

9. In paragraph 5 or paragraph 7, The above electrolyte is a method for removing zinc dentrite from a zinc-bromine battery comprising an aqueous solvent and a zinc / bromine redox couple.

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