Method for initial stabilization of aqueous battery and control system therefor

Abstract

The present document relates to a method for initial stabilization of an aqueous battery by using a liquid electrode. The method may comprise: manufacturing cell blocks of aqueous batteries; performing quality control by repeatedly charging and discharging the manufactured cell blocks a predetermined number of times; shipping cell blocks, which have passed the standards of quality control, in a charged state equal to or exceeding the predetermined standard; and installing the aqueous batteries at an installation position in a state in which the self-discharge rate (SDR) stabilization of the cell blocks is achieved, during a storage and delivery period of the shipped cell blocks.

Description

Initial stabilization method and control system for aqueous batteries

[0001] The following description relates to an aqueous battery, and more specifically, to a method for initial stabilization of an aqueous battery from the perspective of Self-Discharge Rate (SDR) and a system therefor.

[0002] Secondary batteries, unlike primary batteries, which are non-rechargeable, are rechargeable and dischargeable. These secondary batteries are used in a variety of fields, including portable devices like cell phones and laptops, as well as electric vehicles and energy storage systems (ESS).

[0003] Among these secondary batteries, lithium secondary batteries, which are currently the most popular, have a larger capacity than nickel-cadmium batteries or nickel-hydrogen batteries, and their utilization is increasing due to their high energy density per unit weight.

[0004] However, these lithium secondary batteries have the disadvantage of being vulnerable to fire safety, and thus, research on aqueous batteries that can replace / supplement them is actively being conducted.

[0005] There are various types of batteries using liquid electrodes, including VRFB (Vanadium Redox Flow Battery) and VIB (Vanadium Ion Battery) developed by the applicant, as well as aqueous zinc secondary batteries using water-based electrolytes.

[0006] A key characteristic of these aqueous batteries is that energy is stored internally in the form of ions. After charging and discharging, the ions within the battery near the electrodes are fully charged and discharged. However, electrolytes located further from the electrodes and / or in locations where reaction is difficult due to the frame geometry are likely to remain unreacted.

[0007] Accordingly, in the case of aqueous batteries, there is a problem of high SDR when storing cells after charging in the initial cycle, and technology is required to solve this problem.

[0008] In order to solve the above-described problem, one aspect of the present invention is to provide a method and a system for efficiently achieving initial stabilization of an aqueous battery from an SDR perspective.

[0009] Specifically, after manufacturing a cell block of an aqueous battery, the cell block is shipped in a substantially fully charged state during a quality control (QC) procedure, thereby securing time for SDR stabilization of the aqueous battery during the subsequent storage / delivery period, thereby providing a method and system for shortening the separate time for SDR saturation.

[0010] In addition, according to the embodiment, the quality inspection procedure of the water-based battery is specifically stipulated, and the quality inspection procedure is intended to be stipulated so that the final charge state of the manufactured cell block can be shipped in a substantially full state.

[0011] In addition, when installing a water-based battery, the performance of the water-based battery at the installation location is recovered through a balancing cycle, and when SDR stabilization is achieved, the cell blocks are classified by type and a method and system for efficiently performing snapshot balancing through a BMS (Battery Management System) are proposed.

[0012] The problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0013] In one aspect of the present invention for solving the above-described problem, a method for initial stabilization of an aqueous battery using a liquid electrode is proposed, comprising: manufacturing a cell block of the aqueous battery; performing quality control by repeating charging and discharging the manufactured cell block a predetermined number of times; shipping a cell block that has passed the quality control standard in a state of charge higher than a predetermined standard; and installing the aqueous battery at an installation location in a state in which the SDR (Self-Discharge Rate) of the cell block is stabilized during the storage and delivery period of the shipped cell block.

[0014] At this time, installing the water-based battery at the installation location may additionally include performing an initial balancing cycle that performs charging and discharging of the water-based battery within a balancing cycle range.

[0015] In addition, in another aspect of the present invention for solving the above-described problem, a stabilization control system for an aqueous battery utilizing a liquid electrode is proposed, including: a quality control unit configured to perform quality control by repeating charging and discharging a predetermined number of times on a plurality of cell blocks, and to ship cell blocks that have passed the quality inspection standard at a state of charge higher than a predetermined standard; an SDR stabilization unit configured to induce SDR (Self-Discharge Rate) stabilization of the cell blocks during the storage and delivery period of the shipped cell blocks; and an initial balancing unit configured to perform an initial balancing cycle of repeating charging and discharging on cell blocks in which the SDR stabilization has been achieved within a balancing cycle range at an installation location.

[0016] Preferably, the balancing cycle range may have a range smaller than the operating range of charge and discharge for normal operation of the aqueous battery.

[0017]

[0018] In addition, it is preferable that the upper limit of the balancing cycle range corresponds to the upper limit of the operating range, and the lower limit of the balancing cycle range is higher than the lower limit of the operating range.

[0019] Meanwhile, performing the initial balancing cycle may include distinguishing the type of cell block for which balancing is to be performed using a BMS (Battery Management System) while the SDR of the cell block is stabilized.

[0020] At this time, distinguishing the type of the cell block may include distinguishing the cell block into one or more of a first type having high cell internal resistance, a second type having small cell storage capacity, and a third type having high SDR or current efficiency.

[0021] In addition, it is desirable that balancing using the BMS be applied only to the third type cell block.

[0022] In addition, the quality control may include a cell stabilization step including completely discharging undischarged cells in the cell block; a cell block internal resistance measurement step performing charging and discharging through high current; a step inducing complete discharge through discharging through low current; a step measuring the charging current amount through charging and discharging according to a standard cycle after the complete discharge; and a step of completely charging the cell block.

[0023] In the above-described embodiment, the state of charge above the predetermined standard may correspond to a fully charged state of the cell block.

[0024] In addition, the state in which the SDR stabilization is achieved can correspond to a state in which the change in the SDR over time is saturated.

[0025] In addition, the above-described water-based battery may include a VIB (Vanadium Ion Battery), wherein the cell block may correspond to a monoblock of the VIB.

[0026] According to the embodiments of the present invention as described above, initial stabilization of the water-based battery from the SDR perspective can be efficiently achieved.

[0027] Specifically, by shipping cell blocks in a substantially buffered state, time is secured for SDR stabilization of the aqueous battery during the subsequent storage / delivery period, thereby reducing the separate time for SDR saturation.

[0028] In addition, when installing a water-based battery, the performance of the water-based battery at the installation location can be restored through a balancing cycle, and when SDR stabilization is achieved, the cell blocks can be classified by type to efficiently perform snapshot balancing through the BMS.

[0029] The effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention belongs from the description below.

[0030] Figure 1 is a drawing for explaining VRFB.

[0031] FIG. 2 is a drawing for explaining VIB as a water-based battery according to one embodiment of the present invention.

[0032] FIGS. 3 to 6 are diagrams for explaining the cause of the initial high SDR in VIB according to one embodiment of the present invention.

[0033] FIG. 7 is a drawing for explaining the concept of an SDR reduction method according to one embodiment of the present invention.

[0034] FIG. 8 is a flowchart illustrating a method for initial stabilization of an aqueous battery utilizing a liquid electrode according to one embodiment of the present invention.

[0035] FIG. 9 and FIG. 10 are drawings for explaining a quality control method according to one embodiment of the present invention.

[0036] FIGS. 11 to 13 are drawings for explaining a method of installing a water-based battery according to a preferred embodiment of the present invention.

[0037] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In addition, in the drawings, parts irrelevant to the description have been omitted to clearly explain the present invention, and similar parts have been designated with similar reference numerals throughout the specification.

[0038] Throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

[0039]

[0040] As described above, one aspect of the present invention is to provide a method for efficiently achieving initial stabilization of an aqueous battery from an SDR perspective.

[0041] Among various water-based batteries, the VRFB and VIB developed by the applicant are briefly described below.

[0042] Figure 1 is a drawing for explaining VRFB.

[0043] As illustrated in FIG. 1, the VRFB may include a stack (1) of vanadium-based battery cells, a positive electrode electrolyte tank (2), a negative electrode electrolyte tank (3), and a pump (4) as its basic components.

[0044] The stack (1) has a structure in which unit cells (6) are stacked as shown on the right, and the unit cells (6) may have a structure in which electrodes (9) are formed on both sides with a separator (8) in between, and a current collector (7) is arranged surrounding the electrodes (9).

[0045] In this structure, the structure that generates current is explained. First, the electrolyte (S110) in the electrolyte tank (3) is used to generate a flow of electrolyte (S120) using a pump (4), and this flow of electrolyte moves (S140) to the battery stack (1) through a pipe (S130).

[0046] A battery that generates current by returning the electrolyte to the tank after a vanadium redox reaction occurs within the battery stack (1) can be viewed as a VRFB.

[0047] However, in the case of the VRFB described above, there are problems such as energy consumption of the pump (4), imbalance of ions in the tank (2, 3), occurrence of electrode resistance due to uneven flow of electrolyte, and problems with planted pipelines, which result in reduced energy efficiency.

[0048] FIG. 2 is a drawing for explaining VIB as a water-based battery according to one embodiment of the present invention.

[0049] Referring to FIG. 2, the structurally most significant difference from the VRFB described in FIG. 1 is the absence of a pump (3). Instead, in some embodiments, the VIB (200A) is configured such that the first and second electrolytes can be ion-relocated within the positive electrolyte receptacle (106A) of the first half-cell (204A) and the negative electrolyte receptacle (106B) of the second half-cell (204B), respectively. Various structural modifications are possible, and the ion-relocation is possible because of: an osmotic pressure difference between the two receptacles (106A, 106B); a density change in one or both of the first and second electrolytes; diffusion or migration of one or both of the first and second electrolytes; first and second redox half reactions; and / or expansion or contraction of one or both of the first and second electrolytes due to temperature.

[0050] The inventors have recognized that sufficient stability and power supply and energy output for the VIB can be provided if the cross-sectional thickness of the positive and negative electrolyte receiving portions (106A, 106B) does not exceed a specific value, for example, 20 cm, 15 cm, 10 cm, 5 cm, 2 cm, 1 cm, or a range defined by these values.

[0051] A VIB implemented in this manner can offer various technical and commercial advantages. For example, it can minimize or eliminate failures or reliability issues arising from passages such as pipe / tube joints between the battery cells and the receiving compartment (tank), as well as malfunctions / malfunctions of pumps used to circulate the electrolyte, thereby reducing the need for repairs, safety issues, and operating costs associated with the operation of the VIB (200A). Furthermore, since there is no need for a pump to circulate the electrolyte between the battery cells and the receiving compartment (tank), overall efficiency can be improved.

[0052] The present inventors have discovered that the use of a VIB (200A) can increase power or energy density by 2 to 50 times, depending on its size, by eliminating the electrolyte circulation between battery cells and electrolyte tanks required in the VRFB described above with reference to FIG. 1. As described above, power or energy density refers to the power or energy density output relative to the total volume of the energy storage device. Therefore, in the case of a VIB, power or energy density refers to the ratio of the total capacity of the VIB to the power or energy output. In addition, since separate equipment such as tanks, pumps, and circulation pipes required for the electrolyte circulation system are not necessary, the space occupied by the energy storage device can also be significantly reduced.

[0053] Additionally, the overall system complexity can be significantly reduced, thereby eliminating the limitations of commercial applications of VRFBs. For example, unlike the VRFB of Fig. 1, the VIB (200A) can be manufactured in a pack form, similar to lithium-ion batteries, making it suitable for automated processes and mass production, and eliminating the cumbersome construction required to install the VRFB of Fig. 1.

[0054] The following describes the general operating principles and characteristics of a redox battery, using a VIB based on vanadium-based redox pairs as an example. However, embodiments of the present invention are not limited thereto, and it will be appreciated that the principles described below are applicable to other types of redox batteries utilizing other types of redox pairs.

[0055]

[0056] As described above, a liquid electrode can be accommodated in the positive electrolyte receiving portion (106A) and the negative electrolyte receiving portion (106B). A separator (112; membrane) is arranged between these electrolyte receiving portions (106A and 106B), and as described below, it can be seen that protons move between the separators (112) to maintain electrical balance between the electrolytes.

[0057] The liquid electrode contains ions in which a redox (i.e., oxidation-reduction) reaction occurs. The first liquid electrode is an electrolyte in which an anode redox couple is dissolved. The anode redox couple can be implemented with a material including at least one of transition metals such as titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), or zinc (Zn), bromine (Br), and cesium (Cs), and the electrolyte of the present embodiments includes vanadium (V) and V. 2+ / V 3+ The redox couple is dissolved.

[0058] The first liquid electrode may be an acidic aqueous solution that conducts current through ionization, preferably containing sulfuric acid.

[0059] In this embodiment, the first liquid electrode can be manufactured by dissolving VOSO4 (vanadylsulfate), V2O5 (vanadium pentoxide) or other suitable substances in an H2SO4 aqueous solution.

[0060] The first liquid electrode causes the first half-reaction. The first half-reaction is as shown in [Mathematical Formula 1] below, where the right arrow (→) indicates the direction of the discharge reaction and the left arrow (←) indicates the direction of the charge reaction.

[0061] [Mathematical Formula 1]

[0062] V 2+ ←→V 3+ + e-

[0063] In the relationship described above, vanadium divalent ions are oxidized to vanadium trivalent ions during discharge, and vanadium trivalent ions are reduced to vanadium divalent ions during charge.

[0064] Meanwhile, the second liquid electrode is an electrolyte in which the cathode redox couple is dissolved, and in the present embodiments, V 4+ / V 5+ Redox couples may exist.

[0065] The second liquid electrode causes the second half-reaction. The second half-reaction is as shown in [Mathematical Equation 2] below, where the right arrow (→) indicates the direction of the discharge reaction and the left arrow (←) indicates the direction of the charge reaction.

[0066] [Equation 2]

[0067] V 5+ + e - ←→V 4+

[0068] At this time, during discharge, vanadium pentavalent ions are reduced to vanadium tetravalent ions, and during charge, vanadium tetravalent ions are oxidized to vanadium pentavalent ions.

[0069]

[0070] For aqueous batteries, including VRFBs and VIBs, as described above, there is a problem with high SDR in the initial cycle. This is explained using VIB as an example.

[0071] FIGS. 3 to 6 are diagrams for explaining the cause of the initial high SDR in VIB according to one embodiment of the present invention.

[0072] As illustrated in Fig. 3, carbon fibers (310) are randomly oriented between the separators (112) in the VIB. The battery reaction of the VIB mainly occurs on the surface of the carbon fibers (310) of the solid electrode.

[0073] Specifically, FIG. 3 illustrates a case (S320) where electrons move outside the cell during charging via the power supply unit (320). The electrons moved in this manner can induce a charging reaction as in [Mathematical Formula 1] near the carbon fibers (310) of the first liquid electrode. In addition, a charging reaction as in [Mathematical Formula 2] can be induced near the carbon fibers (310) of the second liquid electrode.

[0074] Meanwhile, the liquid electrode of the VIB is a strongly acidic liquid, and thus contains a large number of protons. According to the charging reactions described above, protons can migrate through the separator (112) to maintain electrical balance (S310).

[0075] Therefore, during charging, the ion distribution near the carbon fiber (310) may be different from the vanadium ion oxidation number of the entire liquid electrode, and this can be explained in the same way during discharging.

[0076] Fig. 4 illustrates the concept of a chemical reaction in the vicinity of a carbon fiber (310) and the distance from the carbon fiber (310), and Fig. 5 is a graph showing the oxidation number of vanadium according to the distance from the carbon fiber (310) during charging.

[0077] That is, due to the current flowing in during charging / discharging, a reaction occurs first in an area close to the carbon fiber (310), and as shown in Fig. 6, the deviation may increase while charging continues.

[0078] After this charging process is completed, ions can move due to ion diffusion or diffusion caused by electric fields resulting from electrical imbalance. This can be considered the cause of the SDR described above.

[0079]

[0080] In general, aqueous batteries such as VIB tend to become saturated after a certain number of cycles, as the above phenomenon gradually decreases after several charge / discharge cycles.

[0081] FIG. 7 is a drawing for explaining the concept of an SDR reduction method according to one embodiment of the present invention.

[0082] In relation to the SDR issue described above, the inventors of the present invention have confirmed that SDR decreases during a process of maintaining a high voltage for a certain period of time during the charging stage prior to battery storage. Reference numeral 710 of Fig. 7 illustrates a graph of SDR reduction according to CV (Constant Voltage) charging time. As shown in reference numeral 710, it can be confirmed that SDR saturation gradually occurs as the CV charging time increases.

[0083] Additionally, it can be confirmed that the higher the CV voltage, the faster the saturation state is reached. For example, a faster SDR decline trend can be observed when a CV voltage of 1.5 V is applied compared to when a CV voltage of 1.4 V is applied.

[0084] Meanwhile, reference numeral 720 of FIG. 7 illustrates a graph of SDR reduction according to idle time. As shown in reference numeral 720, it can be confirmed that SDR saturation is gradually achieved as the idle time increases.

[0085] However, both methods illustrated in FIG. 7 require a significant amount of time to stabilize the SDR, potentially reducing the operational efficiency of the aqueous battery. One embodiment of the present invention proposes a method for securing CV charging time and a method for securing idle time, utilizing a method for securing idle time, but securing this idle time as the time it takes for the aqueous battery to be manufactured, stored, and / or delivered to the installation location.

[0086]

[0087] FIG. 8 is a flowchart illustrating a method for initial stabilization of an aqueous battery utilizing a liquid electrode according to one embodiment of the present invention.

[0088] In the method according to the present embodiment, a cell block of an aqueous battery is first manufactured (S610). Here, the term "cell block" is assumed to refer to a form in which multiple cells are stacked, and the VIB described above can be viewed as a concept corresponding to a monoblock. However, the aqueous battery according to the present embodiment may be of various types other than VIB, and is not limited thereto.

[0089] Each cell can assume a structure in which multiple layers are stacked, where the 'layers' can correspond to the separator, solid electrode, current collector, etc. in the VRFB and VIB described above with reference to FIGS. 1 and 2.

[0090] Thereafter, the method according to the present embodiment can perform quality control by repeating charging and discharging on the manufactured cell block a predetermined number of times (S620). The device configuration(s) where this quality control is performed may be referred to as a quality control unit from a system perspective. The quality control unit may include a charger / discharger capable of repeating charging and discharging on the cell block a predetermined number of times. The quality control process is described in detail below with reference to FIGS. 9 and 10.

[0091] Meanwhile, the method according to the present embodiment proposes that cell blocks that have passed the above-described quality control criteria be shipped at a state of charge exceeding a predetermined standard (S630). Preferably, this state of charge exceeding the predetermined standard may correspond to a fully charged state of the cell block, but may also be interpreted as ensuring the maximum possible state of charge based on the state of the charger and / or cell block that can be performed in the quality control step (S620).

[0092] Thereafter, the method according to the present embodiment proposes to install the cell block at the installation location (S640) in a state in which the SDR of the cell block is stabilized during the storage and / or delivery period of the shipped cell block. That is, as described above with reference to reference numeral 720 of FIG. 7, it is proposed to secure a rest period during the storage and / or delivery period of the shipped cell block to secure the SDR saturation state of the water-based battery at the time of installation. The device configuration(s) in which such SDR stabilization is achieved may be referred to as an SDR stabilization unit from a system perspective.

[0093] For example, the SDR stabilization unit may include a warehouse and / or a transport device for storage and / or delivery of the shipped cell blocks, and the warehouse and / or transport device may additionally include a measuring device for checking the SDR saturation state of the aqueous battery.

[0094]

[0095] FIG. 9 and FIG. 10 are drawings for explaining a quality control method according to one embodiment of the present invention.

[0096] Referring to FIG. 9, the quality control process may include a cell stabilization step (710) including completely discharging an undischarged cell, a cell block internal resistance measurement step (S720) performing charging and discharging through a high current, a step (S730) inducing complete discharge through discharging through a low current, a step (S740) measuring the charging current amount through charging and discharging according to a standard cycle after the complete discharge (S730), and a step (S750) of completely charging the cell block.

[0097] Specifically, referring to FIG. 10, first, the cell stabilization step (S710) is performed to completely discharge the undischarged cell during the manufacturing process as described above. To this end, the cell is discharged until it reaches 1.12 V, and then charging and discharging are repeated several times in a CC manner to achieve cell stabilization. FIG. 10 illustrates an example of repeating such charging and discharging for 4 cycles, but the number of repetitions need not be limited thereto.

[0098] The example of Fig. 10 illustrates an example in which the procedures indicated by ① - ④ are additionally performed between the cell stabilization step (S710) and the cell internal resistance measurement step (S720). These steps are procedures for performing charging (① - ②) and discharging (③-④) in a CC manner, and although they are not essential procedures, they may be additionally performed from the perspective of recording for future cause analysis. Preferably, the IR drop is measured using the rest period between procedures ① and ②, and the IR rise is measured using the rest period between procedures ③ and ④, which can be utilized for cause analysis of subsequent step measurements.

[0099] Next, the cell block internal resistance measurement step (S720) performs high-speed charging and discharging in the CC method, and can process it as a defect if it reaches a certain voltage (1.6 V in the case of VIB) before the completion of a set time during high-speed charging. In addition, through this step (S720), it can also be processed as a defect if the CE (Coulomb Efficiency) is less than 99% or the CE is more than 100%. Specifically, if the CE is less than 99%, it can be viewed as a case of a separator abnormality, and if the CE is more than 100%, it can be viewed as a case of an abnormality in the discharge of the previous cycle. This cell block internal resistance measurement step (S720) has the characteristic of being able to classify even if the chargeable capacity is small.

[0100] Next, the step (S730) of inducing complete discharge by discharging at a low current is a step of performing an additional discharge at 0.5 C, as the standard cycle is stipulated as 0.5 C in the VIB group standard. At this time, if discharging at a low current is performed, a deeper discharge can be performed.

[0101] Next, the step (S740) of measuring the charging current through charging and discharging according to the standard cycle may include a CCCV charging step and a CC discharging step. Considering that the charging current corresponds to the energy capacity, energy efficiency can also be measured at this step. Through this, whether the CCCV capacity is defective or the CC capacity is defective can be confirmed.

[0102] Finally, the fully charging step (S750) has the advantage of securing the storage / delivery time as time for SDR stabilization as described above, thereby achieving initial stabilization of the water-based battery.

[0103]

[0104] FIGS. 11 to 13 are drawings for explaining a method of installing a water-based battery according to a preferred embodiment of the present invention.

[0105] As illustrated in FIG. 11, the method of FIG. 8, including installing the aqueous battery (S640), may additionally include performing an initial balancing cycle (S1110) in which the aqueous battery is charged and discharged within a balancing cycle range. This can be viewed as a procedure for restoring the performance of the aqueous battery prior to performing charging and discharging for normal operation when installing the aqueous battery. In addition, as described below, it can also be viewed as a procedure for determining the type of aqueous battery to which balancing using a BMS will be applied.

[0106] The device configuration(s) that performs these initial balancing cycles may be referred to as an initial balancing unit from a system perspective. The initial balancing unit may be placed at the installation location and include a PCS or PMS, etc., for repeating and controlling charging and discharging within the balancing cycle range. Specifically, the initial balancing unit may correspond to a PCS when controlled offline, and may correspond to a PMS when controlled online.

[0107]

[0108] Fig. 12 illustrates a balancing cycle range (1210) when such an initial balancing cycle (S1110) is applied, and as illustrated in Fig. 12, it is preferable that the balancing cycle range (1210) have a smaller range than the operating range (1220) of charging and discharging for the general operation of an aqueous battery. This allows for efficient battery performance recovery by repeating charging and discharging at a fast rate in the aqueous battery. Fig. 13 illustrates the relationship between the number of such balancing cycles (S1110) and the resulting decrease in the voltage difference between cells.

[0109] In addition, as illustrated in FIG. 12, the upper limit of the balancing cycle range (1210) corresponds to the upper limit of the operating range (1220), but it is preferable that the lower limit of the balancing cycle range (1210) be higher than the lower limit of the operating range (1220). As described above, the cell block type classification (S1120) for distinguishing whether to apply balancing using a BMS can be performed through the balancing cycle (S1110), and when distinguishing the type of an aqueous battery, in a low SoC (State of Charge) state, a large deviation between cells can be applied due to a probability problem due to the low ion density of the characteristic of an aqueous battery, so it is proposed to apply the balancing cycle (S1110) preferably in a range of SoC 50% or more.

[0110] Again, referring to FIG. 11, the installation method according to the present embodiment performs type classification (S1120) to distinguish the target of balancing using the BMS, thereby classifying the cell blocks into one or more of a first type (S1130) having high cell internal resistance, a second type (S1140) having small cell storage capacity, and a third type (S1150) having high SDR or current efficiency. Although a cell block is an expression to indicate a form in which multiple cells are stacked, the following description will simply refer to it as a cell, including the case of a single cell.

[0111] Typically, cell balancing using a BMS is applied by lowering the voltage of a cell with a higher voltage than other cells by consuming power through the BMS based on the measured voltage of each cell. However, the inventor of the present invention noted that the reasons why a specific cell shows a higher voltage than other cells need to be examined by classifying them into (1) a first type with high internal cell resistance, (2) a second type with small cell storage capacity, and (3) a third type with high SDR or current efficiency.

[0112] For Type 1 cells with high internal resistance, they have a large IR drop / rise compared to other cells, and thus, the voltage may appear higher than other cells at the end of charging. However, if balancing using a BMS is performed on these Type 1 cells to forcibly match the voltage of other cells, the amount of current being charged will be reduced compared to other cells, and this may cause a problem in that the voltage decreases faster than other cells during discharge. Therefore, it is advantageous not to apply balancing using a BMS to Type 1 cells.

[0113] Furthermore, Type 2 cells with smaller storage capacities may exhibit higher voltages than other cells even when charged with the same amount of charge. Forcing these cells to match their voltages with other cells through balancing via a BMS will result in a reduced current compared to other cells, and discharge deviations may increase. Therefore, even for Type 2 cells, it is advantageous not to apply balancing via a BMS.

[0114] Meanwhile, in the case of the third type cell having low SDR or high current efficiency, the amount of loss is less than that of other cells during charging, so a higher current is stored. If balancing is performed on such cells through BMS, a result similar to that of other cells can be obtained, and in one embodiment of the present invention, it is proposed to perform balancing using BMS only on the third type cell among the first to third types (S1160).

[0115] Balancing based on voltage / current measurements in the initial balancing cycle (S1110) to distinguish the type of the aqueous battery cell for performing such BMS balancing may be referred to as "snapshot balancing." That is, by measuring the voltage / current in the initial balancing cycle (S1110) of the cell as if taking a picture, type distinction (S1120) is performed based thereon, and BMS-based balancing can be performed only for the third type cell (S1150).

[0116] This snapshot balancing is preferably performed when the cell in question is SDR-stabilized. For example, if the SDR is not stabilized when classifying into a Type 3 cell (S1150), classification accuracy may be reduced.

[0117] In one embodiment of the present invention, since the water-based battery is shipped in a fully charged state (S630) as described above and the time required for storage / delivery is utilized as time for SDR stabilization, the initial balancing cycle (S1110) performed at the installation location can be operated by performing it in a state where the SDR of the water-based battery is stabilized.

[0118]

[0119] The detailed description of the preferred embodiments of the present invention disclosed above has been provided to enable those skilled in the art to implement and practice the present invention. While the above description has been made with reference to preferred embodiments of the present invention, those skilled in the art will appreciate that various modifications and variations can be made to the present invention without departing from the scope of the present invention. For example, those skilled in the art can utilize the individual components described in the above-described embodiments in combination with each other.

[0120] Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0121] The initial stabilization method for an aqueous battery and the system therefor according to the embodiments of the present invention as described above can be utilized in various aqueous batteries as well as VRFB and VIB.

Claims

1. A method for initial stabilization of an aqueous battery using a liquid electrode, Manufacturing a cell block of the above water-based battery; Quality control is performed by repeating charging and discharging on the manufactured cell block a predetermined number of times; Cell blocks that have passed the above quality control standards are shipped in a state of charge exceeding the specified standard; An initial stabilization method comprising installing the water-based battery at an installation location during the storage and delivery period of the shipped cell block, with the SDR (Self-Discharge Rate) of the cell block stabilized.

2. In paragraph 1, Installing the above water-based battery at the above installation location, An initial stabilization method further comprising performing an initial balancing cycle in which the aqueous battery is charged and discharged within a balancing cycle range.

3. In paragraph 2, An initial stabilization method wherein the above balancing cycle range has a smaller range than the operating range of charge and discharge for the general operation of the above aqueous battery.

4. In paragraph 3, The upper limit of the above balancing cycle range corresponds to the upper limit of the above operating range, An initial stabilization method wherein the lower limit of the above balancing cycle range is higher than the lower limit of the above operating range.

5. In paragraph 2, Performing the above initial balancing cycle is: An initial stabilization method, which includes distinguishing the type of cell block to be balanced using a BMS (Battery Management System) in a state where SDR stabilization of the above cell block is achieved.

6. In paragraph 5, Distinguishing the type of the above cell block is: An initial stabilization method comprising dividing the cell block into at least one of a first type having high internal cell resistance, a second type having small cell storage capacity, and a third type having high SDR or current efficiency.

7. In paragraph 6, Balancing using the above BMS is an initial stabilization method that is applied only to the third type cell block.

8. In paragraph 1, The above quality control is, A cell stabilization step including completely discharging undischarged cells in the above cell block; Step of measuring the internal resistance of a cell block while charging and discharging through high current; A step of inducing complete discharge by discharging through low current; A step of measuring the charging current by charging and discharging according to a standard cycle after the above complete discharge; and An initial stabilization method comprising the step of fully charging the above cell block.

9. In paragraph 1, A charging state exceeding the above criteria is An initial stabilization method corresponding to a fully charged state of the above cell block.

10. In paragraph 1, The above SDR stabilization state is achieved, An initial stabilization method in which the time-dependent change of the above SDR corresponds to a saturation state.

11. In a stabilization control system for an aqueous battery utilizing a liquid electrode, A quality control unit configured to perform quality control by repeating charging and discharging for a predetermined number of times on a plurality of cell blocks, and to ship cell blocks that have passed the quality inspection criteria in a state of charge higher than a predetermined standard; During the storage and delivery period of the shipped cell block, an SDR stabilization unit for inducing stabilization of the SDR (Self-Discharge Rate) of the cell block; and A stabilization control system for an aqueous battery, comprising an initial balancing unit configured to perform an initial balancing cycle of repeating charging and discharging on a cell block in which the SDR stabilization is achieved within a balancing cycle range at an installation location.

12. In paragraph 11, A stabilization control system for an aqueous battery, wherein the above balancing cycle range has a smaller range than the operating range of charge and discharge for general operation of the aqueous battery.

13. In paragraph 12, The upper limit of the above balancing cycle range corresponds to the upper limit of the above operating range, A stabilization control system for an aqueous battery, wherein the lower limit of the above balancing cycle range is higher than the lower limit of the above operating range.

14. In paragraph 11, The above initial balancing unit is, A stabilization control system for an aqueous battery, configured to distinguish the type of cell block to be balanced using a BMS (Battery Management System) when the SDR stabilization of the above cell block is achieved.

15. In paragraph 11, The above quality control department, A cell stabilization step including completely discharging undischarged cells in the above cell block; Step of measuring the internal resistance of a cell block while charging and discharging through high current; A step of inducing complete discharge by discharging through low current; A step of measuring the charging current by charging and discharging according to a standard cycle after the above complete discharge; and Step of fully charging the above cell block A stabilization control system for an aqueous battery, configured to perform an operation including:

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