Method and apparatus for checking the operating state of a redox battery

Abstract

The present invention provides a method for evaluating the operating state of a vanadium ion battery, comprising repeating a standard cycle a predetermined number of times, the standard cycle including charging one or more of a vanadium ion battery cell, monoblock, module, battery pack, or battery system within a predetermined temperature range to a charge end condition and subsequently discharging to a discharge end condition, and if, among the standard cycles repeated a predetermined number of times, a time interval between the end of a first standard cycle and the start of a second standard cycle is equal to or greater than a first period, further repeating the standard cycle corresponding to an additional number of times in addition to the predetermined number of times.

Description

[Technical Field]

[0001] The present invention relates to battery technology, and more particularly to a method and apparatus for verifying the operating state of a redox battery. [Background technology]

[0002] As global economic growth and global warming progress, the need for renewable and sustainable energy systems, such as solar and wind energy, is increasing. Because these forms of energy are intermittent, energy storage systems (ESSs) are being developed to address these fluctuations, improve the stability of the power grid, and store excess power for supply to end consumers or the power grid as needed. Here, ESSs are also referred to as electrical energy storage systems. While there are various types, electrochemical energy storage systems, such as rechargeable or secondary batteries, can provide cost-effective and environmentally friendly energy storage solutions. Types of electrochemical energy storage systems include lithium-ion batteries, lead-acid batteries, sodium-sulfur (NaS) batteries, and redox flow batteries. Various storage periods, such as short-term, medium-term, and long-term storage, are required for various applications. Each of these electrochemical energy storage systems has different physical and / or chemical properties. To select and design an electrochemical energy storage system suitable for a particular application, competitive factors must be considered, including investment, power, energy, lifespan, recyclability, efficiency, scalability, and maintenance costs.

[0003] Among various electrochemical energy storage systems, the so-called redox battery (RB) is known to be promising for stationary energy storage. RB is an electrochemical energy conversion device that utilizes the oxidation-reduction (redox) reaction of redox species dissolved in a solvent. The advantages of RB include its relative safety, independent scalability in terms of power and energy, long depth of discharge (DOD), and minimal environmental impact. These features make RB suitable for a wide operating power range and discharge time, and for storing batteries generated from renewable sources. However, conventional electrochemical energy storage systems have various challenges and drawbacks. Summary of the Invention [Problem to be solved by the invention]

[0004] In the present invention, the inventors recognized that among the improvements to conventional electrochemical energy storage systems, especially when lithium-ion batteries are applied to energy storage systems (ESS), there still exist risk factors such as the possibility of fire and explosion, and have conducted research and development into safety measures and solutions to these issues.

[0005] Based on the above-mentioned problem recognition, in order to solve this problem, the inventors set out to find a specific technology to make redox batteries applicable to energy storage systems (ESS).

[0006] Therefore, one of the objects of the present invention is to provide a method and apparatus for carrying out various evaluations of redox batteries that are required for application to energy storage systems (ESS) or other applications.

[0007] Another object of the present invention is to provide a method and apparatus for evaluating redox batteries, which can perform measurements necessary to confirm the operating conditions that are compatible with the unique electrochemical technical characteristics of vanadium applicable to redox batteries. [Means for solving the problem]

[0008] In order to solve the above problem, at least one embodiment of the present invention provides a method for setting one or more related normalized standards for more accurate measurement of a redox battery cell, obtaining a voltage window by taking into account electrochemical characteristics of the redox battery cell, including vanadium ion distribution, and charging or discharging the redox battery cell by using the normalized standards and referring to the obtained voltage window.

[0009] According to at least one embodiment of the present invention, there is provided a semiconductor chip structure including a setting element configured to set one or more standard conditions associated with a redox battery, and a measuring element configured to perform one or more measurements on the redox battery in accordance with the set standard conditions.

[0010] According to at least one embodiment of the present invention, there is provided a method for evaluating the operating state of a vanadium ion battery, the method comprising: repeating a first type of standard cycle a predetermined number of times, the first type including charging any one or more of the vanadium ion battery cells, a monoblock including one or more of the cells connectable in series or parallel, a module in which one or more of the monoblocks are connected in series or parallel, or a battery pack or battery system including one or more of the monoblocks or modules to a charge end condition within a predetermined temperature range, and subsequently discharging to a discharge end condition, wherein the vanadium ion battery cells include a first electrode at which a first half-reaction of vanadium ions in a first electrolyte solution takes place; a second electrode at which a second half-reaction of vanadium ions in a second electrolyte solution takes place; a separator disposed between the first electrode and the second electrode; and a frame supporting the separator; and when, during the standard cycles repeated a predetermined number of times, a time interval between the end of the first standard cycle and the start of a second standard cycle is equal to or greater than a first period, the method further comprises repeating the standard cycle a corresponding additional number of times in addition to the predetermined number of times.

[0011] Furthermore, according to at least one embodiment of the present invention, there is provided a system for evaluating the operating state of a vanadium ion battery, the system comprising: a vanadium ion battery cell; a monoblock including one or more of the cells and connectable in series or parallel; a module including one or more of the monoblocks connected in series or parallel; a battery pack or a battery system including one or more of the monoblocks or modules; a system for charging the vanadium ion battery cell to a charge end condition within a predetermined temperature range, and subsequently discharging the vanadium ion battery cell to a discharge end condition, the vanadium ion battery cell comprising: a first electrode at which a first half-reaction of vanadium ions in a first electrolyte solution takes place; a second electrode at which a second half-reaction of vanadium ions in a second electrolyte solution takes place; a separator disposed between the first electrode and the second electrode; and a frame for supporting the separator; and the system is configured to further repeat the standard cycle corresponding to an additional number of times in addition to the predetermined number of times if, during the standard cycles repeated the predetermined number of times, the time interval between the end of the first standard cycle and the start of a second standard cycle is equal to or greater than a first period. [Effects of the Invention]

[0012] The present invention has the effect of enabling more accurate measurements and estimations to be made on a redox battery by setting and using standard conditions for the redox battery, compared to when the standard conditions are not set / used.

[0013] Furthermore, the present invention allows for more efficient charging and / or discharging of redox batteries by using standard conditions for redox batteries, enabling more accurate battery management, power control, and operation of energy storage systems.

[0014] In particular, the present invention can enable suitable application of redox batteries to energy storage systems (ESS). [Brief explanation of the drawings]

[0015] [Figure 1] 1 is an exemplary diagram illustrating a structure of a redox battery according to at least one embodiment of the present invention; [Figure 2] FIG. 1 is a perspective view of a redox battery in accordance with at least one embodiment of the present invention. [Figure 3] 3 is a cross-sectional view taken along the dotted line AA in FIG. 2. [Figure 4] 1 is an exemplary diagram of a module in which a plurality of redox batteries are stacked in accordance with at least one embodiment of the present invention. [Figure 5] 1 is a conceptual diagram illustrating some features of a constant current (CC) control method and a constant voltage (CV) control method applied to battery charging according to at least one embodiment of the present invention. [Figure 6] 1 is an exemplary diagram showing the relationship between voltage and current during charging and discharging at both electrodes of a vanadium flow redox battery (VFRB) in accordance with at least one embodiment of the present invention. [Figure 7] FIG. 1 is an exemplary graph of a data set including data for charging and discharging a battery at a constant current in accordance with at least one embodiment of the present invention. [Figure 8] FIG. 1 is an exemplary diagram showing basic electrochemical characteristics of a vanadium-based battery according to at least one embodiment of the present invention. [Figure 9] 1A and 1B are illustrative diagrams showing two contrasting situations of battery cell resistance and IR drop at inflection points during charging or discharging in accordance with at least one embodiment of the present invention. [Figure 10] 1 is an exemplary diagram showing experimental results of determining the final emission voltage using a pulsed galvanostatic measurement curve and an internal resistance curve at a high current density according to at least one embodiment of the present invention; FIG. [Figure 11]1 is an exemplary diagram illustrating the relationship of open circuit voltage (OCV) to state of charge (SoC) for a short charge period, a long charge / discharge period, and a short discharge period in accordance with at least one embodiment of the present invention. [Figure 12] 1 is an exemplary diagram illustrating the effect of ambient temperature on a vanadium-based battery (VIB) according to at least one embodiment of the present invention. [Figure 13] 1 is an exemplary flowchart illustrating a procedure for entering a standard state of a redox battery in accordance with at least one embodiment of the present invention. [Figure 14] FIG. 14 is a conceptual diagram of an exemplary apparatus capable of carrying out the procedure of FIG. 13. [Figure 15] 1 is a conceptual diagram of an exemplary semiconductor chip structure in accordance with at least one embodiment of the present invention. [Figure 16] FIG. 1 is a conceptual diagram of an example battery management system in accordance with at least one embodiment of the present invention. [Figure 17] FIG. 1 is a conceptual diagram of an exemplary apparatus in accordance with at least one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The advantages and features of the present invention, and methods for achieving them, will become apparent from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various different forms. These embodiments are provided solely to complete the disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art. The present invention is defined solely by the claims. The same reference numerals refer to the same elements throughout the specification.

[0017] Although terms such as "first," "second," etc. are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a first component may be a second component.

[0018] Throughout the specification, unless specifically stated to the contrary, each element may be singular or plural.

[0019] Hereinafter, when an arbitrary configuration is arranged "on the top (or bottom)" of a component, or "above (or below)" a component, it may mean that the arbitrary configuration is not only arranged in contact with the top surface (or bottom surface) of the component, but also that another configuration may be interposed between the component and the arbitrary configuration arranged above (or below) the component.

[0020] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, but that there may also be other components "intervening" between each component, or that each component may be "coupled," "coupled," or "connected" via other components.

[0021] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "comprise" or "include" should not be interpreted as including all of the components or steps described in the specification, but should be interpreted as including some of the components or steps not being included, or including additional components or steps.

[0022] Throughout the specification, "A and / or B" means A, B, or A and B, unless otherwise specified to the contrary, and "C to D" means at least C and at most D, unless otherwise specified to the contrary.

[0023] Vanadium-based batteries, such as vanadium redox batteries (VRBs), vanadium redox flow batteries (VRFBs or VFRBs), vanadium flow batteries (VFBs), and vanadium-ion batteries (VIBs), can be considered a type of redox battery and are being applied or expected to be utilized in various energy storage systems (ESS / EES) and other applications related to the battery industry. Vanadium-based batteries have some advantages of the basic redox flow battery (RFB), but compared to conventional non-vanadium-based redox flow batteries (RFBs), they have a lower risk of fire and are less likely to break due to the properties of vanadium itself.

[0024] Referring to FIG. 1 , the most significant structural difference from a conventional redox flow battery (RFB) is the absence of a pump. Instead, in some embodiments of the redox battery 200A, the first and second electrolytes are self-circulating within the anolyte-receiving portion 106A of the first half-cell 204A and the catholyte-receiving portion 106B of the second half-cell 204B. Various structural variations are possible, and the self-circulation can be achieved by: an osmotic pressure difference between the two receptacles 106A and 106B; a change in density of the first and / or second electrolytes; diffusion or migration of the first and / or second electrolytes; first and / or second redox half reactions; and / or temperature-induced expansion or contraction of the first and / or second electrolytes. The present inventors have recognized that sufficient stability, power supply, and energy output for a vanadium-based battery can be provided when the cross-sectional thickness of the anode and cathode electrolyte-containing portions 106A, 106B does not exceed a predetermined dimension, e.g., 20 cm, 15 cm, 10 cm, 5 cm, 2 cm, 1 cm, or a range defined by these values.

[0025] The redox battery thus embodied can provide various technical and commercial advantages. For example, it can minimize or eliminate failures or reliability issues that occur in passages such as pipes / fittings between the battery cells and the container (tank), and failures / malfunctions of pumps used for electrolyte circulation, thereby reducing the need for repairs, safety issues, and operating costs associated with the operation of the redox battery 200A. Furthermore, since it is not necessary to use a pump to circulate the electrolyte between the battery cells and the container (tank), overall efficiency can be improved. The inventors have recognized that the use of the redox battery 200A can increase the power or energy density by 2 to 50 times, depending on its size, by eliminating the electrolyte circulation between the battery cells and the electrolyte tank required in conventional RFBs. 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, the power or energy density of a redox battery refers to the ratio of the total capacity of the redox battery to the power or energy output. In addition, the space occupied by the energy storage device can be significantly reduced because there is no need for separate tanks, pumps, circulation pipes, etc. required for the electrolyte circulation system. Furthermore, the complexity of the entire system can be significantly reduced, eliminating constraints on the commercial application of redox batteries. For example, unlike conventional RFBs, the Redox Battery 200A can be manufactured in pack form like lithium-ion batteries, making it suitable for automated processes and mass production, and eliminating the need for the cumbersome construction required to install conventional RFBs.

[0026] The overall operating principles and characteristics of redox batteries will be described below using a vanadium (V) redox battery based on vanadium-based redox pairs as an example, although it should be understood that embodiments of the present invention are not limited thereto and that the principles described below are also applicable to other types of redox batteries that utilize other types of redox pairs.

[0027] FIG. 2 is a perspective view of a redox battery according to at least one embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along the dotted line AA in FIG.

[0028] 2 and 3, a vanadium ion battery (VIB) is used as an example of a redox battery according to an embodiment of the present invention, and includes a first liquid electrode in which a first half-reaction occurs, a second liquid electrode in which a second half-reaction occurs, a hollow frame 110 forming a first electrode receiving portion 111a which is a space in which the first liquid electrode is stored and a second electrode receiving portion 111b which is a space in which the second liquid electrode is stored, and a battery connected to the frame 110 to form the first electrode receiving portion 111a and the second electrode receiving portion 111b. a separation membrane 120 disposed between the first electrode accommodating portion 111a of the frame 110 and electrically connected to the first liquid electrode; a first current collector 130a in contact with the first electrode accommodating portion 111a side of the frame 110 and electrically connected to the first liquid electrode; a second current collector 130b in contact with the second electrode accommodating portion 111b side of the frame 110 and electrically connected to the second liquid electrode; a first solid electrode 150a disposed in the first electrode accommodating portion 111a and impregnated with the first liquid electrode; and a second solid electrode 150b disposed in the second electrode accommodating portion 111b and impregnated with the second liquid electrode.

[0029] The liquid electrodes contain ions in which a redox (i.e., oxidation-reduction) reaction occurs. The first liquid electrode is an electrolyte in which a cathode redox couple is dissolved. The cathode redox couple can be embodied as a material containing at least one of the transition metals titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), or zinc (Zn), bromine (Br), or cesium (Cs). In this embodiment, the electrolyte contains vanadium (V), and V 2+ / V 3+The redox couple can be dissolved in the first liquid electrode, which is an acidic aqueous solution that conducts current by ionization, preferably containing sulfuric acid. In this embodiment, the first liquid electrode can be fabricated by dissolving VOSO4 (vanadylsulfate), VO2O5 (vanadium pentoxide), or other suitable material in an H2SO4 aqueous solution.

[0030] The first liquid electrode induces a first half-reaction, which is as follows, where the right-pointing arrow (->) indicates the direction of the discharge reaction and the left-pointing arrow (<-) indicates the direction of the charge reaction: V 2+ <- -> V 3+ + e -

[0031] During discharge, the divalent vanadium ions are oxidized to trivalent vanadium ions, and during charge, the trivalent vanadium ions are reduced to divalent vanadium ions.

[0032] The first liquid electrode is surrounded by the frame 110, the first current collector 130a, and the separation membrane 120. The frame 110 prevents the first liquid electrode from leaking in the in-plane direction between the first current collector 130a and the separation membrane 120. The first liquid electrode is accommodated in the first electrode accommodating portion 111a. The first liquid electrode is preferably impregnated in the first solid electrode 150a.

[0033] The first liquid electrode is electrically connected to the first current collector 130a, and electrons move to the first current collector 130a during discharge, and electrons from the first current collector 130a move to the first liquid electrode during charge. The first liquid electrode is in contact with the separation membrane 120, and hydrogen cations (protons) move through the separation membrane 120.

[0034] The second liquid electrode is an electrolyte in which an anode redox couple is dissolved. The anode redox couple can be realized with a material containing at least one of the transition metals titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), zinc (Zn), bromine (Br), and cesium (Cs). In this embodiment, V4 + / V5 + A redox couple exists. The second liquid electrode is an acidic aqueous solution that conducts current by ionization, typically sulfuric acid. In this example, the second liquid electrode can be fabricated by dissolving VOSO4 (vanadylsulfate) or VO5 (vanadium pentoxide) or other suitable substances in an H2SO4 aqueous solution.

[0035] The second liquid electrode induces a second half-reaction, which is as follows, where the right-pointing arrow (->) indicates the direction of the discharge reaction and the left-pointing arrow (<-) indicates the direction of the charge reaction: V 5+ + e - <- -> V 4+

[0036] During discharge, the vanadium pentavalent ions are reduced to vanadium tetravalent ions, and during charge, the vanadium tetravalent ions are oxidized to vanadium pentavalent ions.

[0037] The second liquid electrode is surrounded by the frame 110, the second current collector 130b, and the separation membrane 120. The frame 110 prevents the second liquid electrode from leaking in the in-plane direction between the second current collector 130b and the separation membrane 120. The second liquid electrode is accommodated in the second electrode accommodating portion 111b. The second liquid electrode is preferably impregnated in the second solid electrode 150b.

[0038] The second liquid electrode is electrically connected to the second current collector 130b, and electrons move to the second current collector 130b during charging, and electrons from the second current collector 130b move to the second liquid electrode during discharging. The second liquid electrode is in contact with the separation membrane 120, and hydrogen cations (protons) move through the separation membrane 120.

[0039] As mentioned above, the first and second liquid electrodes are made of the same components or the same material. The first and second liquid electrodes contain vanadium ions in an electrolyte of the same components. Hereinafter, the first and second liquid electrodes will be collectively referred to as liquid electrodes.

[0040] The frame 110 is formed in a hollow rectangular shape. Depending on the embodiment, the frame 110 may be formed in a diamond shape, a circle, a triangle, a polygon with pentagons or more, or the like. The frame 110 has a predetermined thickness in an out-of-plane direction and forms a first electrode receiving portion 111a and a second electrode receiving portion 111b. Depending on the implementation method and necessary mechanical requirements of the vanadium-based battery, the shape and / or thickness of the frame 110 may be changed and may be determined taking into account the relationship between conflicting factors such as overall size, weight, battery capacity, charge / discharge behavior, and manufacturing costs.

[0041] The hollow space of the frame 110 is divided into a first electrode receiving portion 111a and a second electrode receiving portion 111b by a separation membrane 120. The separation membrane 120 is coupled to the center of the frame 110 in the out-of-plane direction (thickness direction) and supports the separation membrane 120.

[0042] The frame 110 has a first current collector 130a disposed on one side in the out-of-plane direction and a second current collector 130b disposed on the other side. The hollow of the frame 110 is sealed by the first current collector 130a and the second current collector 130b. The frame 110 is disposed between the first current collector 130a and the second current collector 130b to prevent the first liquid electrode and the second liquid electrode from leaking in the in-plane direction. The frame 110 forms a first electrode receiving portion 111a between the first current collector 130a and the separator 120, and a second electrode receiving portion 111b between the second current collector 130b and the separator 120.

[0043] The frame 110 accommodates the first and second liquid electrodes. The frame 110 has a first solid electrode 150a and a second solid electrode 150b disposed therein. The frame 110 has a first gasket 160a attached to one end thereof and a second gasket 160b attached to the other end thereof.

[0044] The separation membrane 120 is disposed inside the frame 110 and separates the first and second liquid electrodes, allowing hydrogen cations (protons) to move between them. The separation membrane 120 is disposed inside the frame 110 and separates the first electrode housing portion 111a from the second electrode housing portion 111b. The separation membrane 120 is disposed between the first current collector 130a and the second current collector 130b. The ends of the separation membrane 120 are connected to the frame 110. Hydrogen cations move from the first liquid electrode to the second liquid electrode during discharge, and move from the second liquid electrode to the first liquid electrode during charge.

[0045] The separation membrane 120 can include perfluorinated ionomers, partially fluorinated polymers, and non-fluorinated hydrocarbons. The separation membrane 120 can be formed of or include commercially available materials such as Nafion®, Flemion®, NEOSEPTA-F®, or Gore Select®.

[0046] Although the separator 120 is required to prevent the first and second liquid electrodes from mixing with each other, a crossover phenomenon can occur during charging and discharging, in which vanadium ions and water contained in the first and second liquid electrodes pass through the separator 120. This can cause an imbalance between the amount of the first and second liquid electrodes, which can affect the performance and lifespan of the battery (secondary battery). While this imbalance can be resolved in a conventional redox secondary battery with a liquid electrode tank and pump, in this embodiment, where a relatively small amount of liquid electrode is present only within the secondary battery, even a slight imbalance in the liquid electrodes can affect the performance and lifespan of the redox battery. Therefore, by connecting the first electrode receiving portion 111a and the second electrode receiving portion 111b, a small amount of liquid electrode can move, thereby eliminating the imbalance caused by crossover.

[0047] The first current collector 130a is disposed on one side of the frame 110 and forms a first electrode receiving portion 111a together with the frame 110 and the separator 120. The first current collector 130a is disposed parallel to and spaced apart from the second current collector 130b. The first current collector 130a is in close contact with a first gasket 160a disposed on the frame 110. The first current collector 130a contacts a first insulator 170a and does not directly contact the first liquid electrode or the second liquid electrode flowing through the transition portion 112. The first current collector 130a is electrically connected to the first liquid electrode, and electrons move therethrough to allow current to flow during charging and discharging.

[0048] The second current collector 130b is disposed on the other side of the frame 110 and forms a second electrode receiving portion 111b together with the frame 110 and the separator 120. The second current collector 130b is disposed parallel to and spaced apart from the first current collector 130a. The second current collector 130b is in close contact with a second gasket 160b disposed on the frame 110. The second current collector 130b contacts a second insulator 170b and does not directly contact the first or second liquid electrodes flowing through the transition portion 112. The second current collector 130b is electrically connected to the second liquid electrode, and electrons move between the second liquid electrodes to allow current to flow during charging and discharging.

[0049] The secondary battery according to an embodiment of the present invention may further include a first gasket 160a that seals between the first current collector 130a and the frame 110, and a second gasket 160b that seals between the second current collector 130b and the frame 110.

[0050] The first gasket 160a and the second gasket 160b may be made of elastic rubber or synthetic resin, and may be formed in the shape of a rectangular strip.

[0051] The first solid electrode 150a is impregnated with a first liquid electrode and disposed in the first electrode receiving portion 111a. The first solid electrode 150a is disposed surrounded by the frame 110, the first current collector 130a, and the separation membrane 120. The first solid electrode 150a includes a carbon-based material such as carbon or graphite felt, carbon cloth, carbon black, graphite powder, or graphene. The first solid electrode 150a may be formed in a porous rectangular parallelepiped shape. The first solid electrode 150a may have a thickness greater than the thickness of the first electrode receiving portion 111a in the out-of-plane direction. In this case, the first solid electrode 150a is compressed and accommodated in the first electrode receiving portion 111a. The first solid electrode 150a is in close contact with the first current collector 130a and the separation membrane 120.

[0052] The second solid electrode 150b is impregnated with a second liquid electrode and disposed in the second electrode receiving portion 111b. The second solid electrode 150b is disposed surrounded by the frame 110, the second current collector 130b, and the separation membrane 120. The second solid electrode 150b includes a carbon-based material such as carbon or graphite felt, carbon cloth, carbon black, graphite powder, or graphene. The second solid electrode 150b may be formed in a porous rectangular parallelepiped shape. The second solid electrode 150b may have a thickness greater than the thickness of the second electrode receiving portion 111b in the out-of-plane direction. In this case, the second solid electrode 150b is compressed and accommodated in the second electrode receiving portion 111b. The second solid electrode 150b is in close contact with the second current collector 130b and the separation membrane 120.

[0053] The overall configuration of the secondary battery according to the present invention thus configured will be described below. A separator 120 is disposed at the center in the out-of-plane direction of a rectangular frame 110 having a predetermined thickness, a first current collector 130a is disposed on one out-of-plane side of the frame 110, and a second current collector 130b is disposed on the other out-of-plane side, thereby forming a first electrode receiving portion 111a and a second electrode receiving portion 111b. That is, the frame 110 is disposed between the first current collector 130a and the second current collector 130b, and the separator 120 is disposed within the frame 110.

[0054] FIG. 4 is an exemplary diagram of a module in which multiple redox batteries are stacked in accordance with at least one embodiment of the present invention.

[0055] As shown in FIG. 4, when a plurality of batteries (secondary batteries) are formed into a module by a plurality of frames 110, a plurality of first current collectors 130a, and a plurality of second current collectors 130b, the plurality of first current collectors 130a are electrically connected by bus bars (not shown) to connect the plurality of secondary batteries in parallel.

[0056] The first current collector 130a may include a first metal current collector 131a formed of metal and electrically connected to the bus bar, and a first carbon current collector 132a disposed between the first metal current collector 131a and the frame 110.

[0057] The first carbon current collector 132a is made of a material such as graphite, carbon, or carbon plastic, and has high electrical conductivity and high acid resistance. The first carbon current collector 132a is disposed between the first liquid electrode and the first metal current collector 131a to allow electrons to move between them while preventing the first metal current collector 131a from oxidizing. The first carbon current collector 132a may be formed in the shape of a rectangular plate or may be coated on the first metal current collector 131a.

[0058] The first metal current collector 131a is made of a metal with high electrical conductivity, such as copper or aluminum. The first metal current collector 131a is formed in a rectangular plate shape, and a portion of the first metal current collector 131a may protrude to be connected to a bus bar.

[0059] The first metal current collector 131a may be formed of a flexible thin film or a rigid plate. When a plurality of secondary batteries form a module as shown in FIG. 4, the plurality of first metal current collectors 131a may be formed of a flexible thin film, but some may be formed of a rigid plate.

[0060] A first carbon current collector 132a is disposed on one surface of the first metal current collector 131a. When a plurality of secondary batteries form a module as shown in Fig. 4, a first carbon current collector 132a is disposed on each of both surfaces of the first metal current collector 131a.

[0061] As shown in FIG. 4, when a plurality of secondary batteries are formed into a module by a plurality of frames 110, a plurality of first current collectors 130a and a plurality of second current collectors 130b shown in FIG. 3, the plurality of second current collectors 130b are also electrically connected by bus bars (not shown) to connect the plurality of secondary batteries.

[0062] That is, the second current collector 130b in FIG. 3, like the first current collector 130a shown in FIG. 4, includes a second metal current collector 131b formed of metal and electrically connected to the bus bar, and a second carbon current collector 132b arranged between the second metal current collector 131b and the frame 110.

[0063] The second carbon current collector 132b is made of a material such as graphite, carbon, or carbon plastic, and has high electrical conductivity and high acid resistance. The second carbon current collector 132b is disposed between the second liquid electrode and the second metal current collector 131b to allow electrons to move between them while preventing the second metal current collector 131b from oxidizing. The second carbon current collector 132b may be formed in the shape of a rectangular plate or may be coated on the second metal current collector 131b.

[0064] The second metal current collector 131b may be made of a metal with high electrical conductivity, such as copper or aluminum, and may have a rectangular plate shape with a protruding portion connected to a bus bar.

[0065] The second metal current collector 131b may be formed of a flexible thin film or a rigid plate. As shown in Figure 4, when a plurality of secondary batteries form a module, the plurality of second metal current collectors 131b may be formed of a flexible thin film, but only a portion of the second metal current collectors 131b may be formed of a rigid plate.

[0066] The second metal current collector 131b has a second carbon current collector 132b disposed on one side thereof. As shown in Fig. 4, when a plurality of secondary batteries form a module, the second metal current collector 131b has a second carbon current collector 132b disposed on each side thereof.

[0067] 4, a module is constructed by alternately repeating the configurations described above with reference to Figures 2 and 3. That is, a first current collector 130a may be disposed between a plurality of frames 110 to which separators 120 are coupled, and a second current collector 130b may be disposed between a plurality of frames 110 to which separators 120 are coupled.

[0068] A first carbon current collector 132a and a first metal current collector 131a may be stacked in this order on the first electrode housing portion 111a side, and a second carbon current collector 132b and a second metal current collector 131b may be stacked in this order on the second electrode housing portion 111b side.

[0069] Redox battery charging and discharging operation The charging and discharging operations of a redox battery (for example, a vanadium-based battery) will be described below.

[0070] Setting the exact charge / discharge voltage range of a battery is not an easy task. Battery voltage is affected by the composition of battery components, the charge / discharge environment, the control method, etc. In such an environment with many variables, there are only two substantial values ​​that can be measured: voltage and current.

[0071] Generally, battery manufacturers have used a trial-and-error method to determine the optimal charge / discharge voltage range for their products. Many batteries exhibit a phenomenon in which the voltage (electromotive force) changes rapidly at both ends of the graph (curve) showing the state of charge (SoC) characteristics. In other words, the slope of the charge / discharge graph changes rapidly as the battery approaches a fully charged / fully discharged state. By measuring this slope, battery manufacturers can determine the optimal "charge / discharge window" for their products, which is usually called the "rated voltage range."

[0072] However, the conventional trial and error method involves many variables and is not optimal. The inventors of the present invention recognized this and have made efforts to develop and refine a more fundamental voltage range.

[0073] FIG. 5 is a conceptual diagram for explaining some features of a constant current (CC) control method and a constant voltage (CV) control method applied to battery charging according to at least one embodiment of the present invention.

[0074] Referring to Figure 5, when charging (or discharging) a battery, CC control and / or CV control are used. CV control fixes the voltage, so even when the SoC is high, the current decreases without exceeding a certain voltage. In other words, it is a safe control method when the battery is near full charge. On the other hand, when CV control is applied at a low SoC, the potential difference between the two electrodes is low, but the voltage is high, resulting in a large IR value and a sudden increase in the current, which can be dangerous.

[0075] In contrast, CC control fixes the amount of current, so the same amount of charge moves per unit time regardless of the SoC. This means that it is a safe control method when the SoC is low. However, if the response to a sudden voltage change caused by a high SoC is delayed, the safe voltage range may be exceeded momentarily.

[0076] Therefore, many batteries are charged using CC-CV control in conjunction with each other for safe charging.

[0077] Vanadium-based batteries are charged and discharged through oxidation-reduction (i.e., redox) reactions, so the voltage (potential) difference between the positive and negative electrodes has a significant impact on the storage and release of energy. The relevant redox reactions are as follows:

[0078] Negative electrode: V 2+ <-> V 3+ + e - E 0 = -0.255 V Positive electrode: VO2 + + e - + 2H + <-> VO 2+ + H2O E 0 = +1.004 V Overall Response: VO2 + + V 2+ + 2H + <-> VO 2+ + V 3+ H2O E 0 = + 1.259 V

[0079] In addition, a potential difference occurs due to changes in the concentration of the positive and negative electrodes (liquid electrodes), which appears as the open circuit voltage (OCV) of the battery cell (I=0).

[0080] SoC theoretically indicates the degree to which the density / concentration of each of the trivalent and tetravalent electrolytes changes from 100% to 0%.

[0081] The equilibrium potential (E eq ) is calculated according to the Nernst's equation, which relates ion concentration to voltage, as follows:

[0082]

number

[0083] The voltage measured outside a battery cell is affected by the current applied during charging and discharging. The rise and fall of voltage due to the product of current and resistance (i.e., V=IR) is commonly referred to as "ohmic loss."

[0084] However, the actual operating voltage of VRFB differs from this thermodynamic value. Because an overpotential is required in addition to the thermodynamic voltage, the charging voltage must be approximately 1.2 V or higher.

[0085] FIG. 6 is an exemplary diagram showing the relationship between voltage and current during charging and discharging at both electrodes of a vanadium flow redox battery (VFRB) according to at least one embodiment of the present invention.

[0086] Referring to FIG. 6, assuming that the overall chemical kinetics are driven by charge transfer in an electrochemical reaction, the equations that represent the relationship between voltage and current appearing through both electrodes of a VFRB during charging and discharging are as follows:

[0087]

number

[0088] Here, ηa represents the overvoltage on the anode side, and ηc represents the overvoltage on the cathode side. As shown in the above formula, there is activity and overvoltage (anodic / cathodic overpotential) due to current, but in the case of vanadium-ion batteries (VIB), unlike lithium-ion batteries (LIB) or lead-acid batteries, the ion phase (liquid → solid or solid → liquid) does not change, so these effects can be ignored.

[0089] The sections where the battery is damaged or its efficiency decreases are the sections where the graph changes suddenly in Figure 8, which will be described below, i.e., the section where the battery is charged at a high SoC and the section where the battery is discharged at a low SoC. In other words, the key to battery control is to properly set the voltage conditions for the end of charging and the end of discharging.

[0090] The following describes methods for making voltage range measurements according to some embodiments of the present invention. Figure 7 shows graphs containing data sets when charging / discharging a battery at a constant current. These graphs are not related to VIB, but are shown for technical background understanding.

[0091] For each of the three graphs shown, you can see that the slope of the graph changes suddenly just before the start / end of charging and just before the start / end of discharging. For various reasons, such as ease of control, safe operation, and battery life, the dotted linear section is generally used.

[0092] Here, how to set the ends of the voltage interval can be determined by taking into consideration various factors and conditions. For example, the ends of the voltage interval can be set to intervals that appear reasonably linear. Alternatively, the change in slope can be measured and points where a certain level of change is observed can be considered as the ends of the voltage interval. Alternatively, the ends of the voltage interval can be set as efficient intervals through trial and error. Furthermore, the voltage interval can be set based on battery experiments and operational experience. However, due to these fundamental questions and various considerations, the inventors have focused on and proposed the following technical approach.

[0093] Although the inventors have focused their research and development efforts on vanadium-based batteries such as VIBs and VRFBs, it will be understood that the concepts and features described herein are applicable to other types of batteries.

[0094] Based on the electrochemical characteristics of vanadium-based batteries, the following experimental method is proposed to determine the suitable voltage range for vanadium-based batteries.

[0095] FIG. 8 is an exemplary diagram showing the basic electrochemical characteristics of a vanadium-based battery according to at least one embodiment of the present invention.

[0096] The example in Figure 8 shows the electrochemical characteristics of a VIB, a vanadium-based battery. (a) shows the pulsed galvanostatic measurement curve, (b) shows the battery internal resistance curve, and (c) shows the pulsed galvanostatic charge / discharge curve.

[0097] To observe the electrochemical reaction due to the dynamic behavior of vanadium ions occurring between the solid and liquid electrodes inside the battery, pulsed constant current measurements were carried out. -1A pulse current of 1.0 V was repeatedly applied for 1 minute, followed by a 5-minute open-circuit rest period in the range of 0 V to 20 V. During the pulse charge and discharge, the pulse voltage remained consistently low in the range of approximately 1.2 V to 1.6 V, indicating that the internal polarization of the VIB remained low in the range of 1.2 V to 1.6 V. However, once the voltage exceeded the range of 1.2 V to 1.6 V, the pulse voltage suddenly increased, indicating that the vanadium reactant in the liquid electrode was consumed, resulting in an increase in the cell's internal resistance.

[0098] To clearly observe the dynamic behavior of vanadium ions, the internal resistance of the VIB was calculated by dividing the pulse voltage by the current using the pulsed constant current charge / discharge data, as shown in Figure 8(b). The internal resistance was observed to be constant between 1.2 and 1.6 V, with only a small resistance of approximately 20 mΩ, indicating that new vanadium reactants were instantly supplied to the carbon reaction site. This phenomenon suggests that the carbon electrode expels reacted materials and allows access to new reactants, which is considered to be the driving force behind the microfluidic movement inside the VIB. Meanwhile, the battery internal resistance increases rapidly when the voltage exceeds the 1.2–1.6 V range due to the consumption of vanadium reactants. Therefore, operating the VIB outside the 1.2–1.6 V open-circuit voltage (OCV) range results in energy loss.

[0099] The inventors have devised a relatively simple basic procedure for establishing a voltage range suitable for battery control. According to this basic procedure, when charging and / or discharging a battery using a constant current, (i) set or establish specific time intervals periodically or otherwise, (ii) initialize the current to zero for multiple time intervals, and (iii) measure the IR drop for each interval. That is, a voltage range suitable for VIB control or the like can be established by measuring internal resistance values ​​corresponding to open-circuit voltage (OCV) values, which correspond to state-of-charge (SoC) values ​​or ranges.

[0100] The VIB contains suitable electrolytes, which are called liquid electrodes located at the anode (or positive electrode) and cathode (or negative electrode). If the amount or degree of electrical charge of these electrolytes changes, or if the average oxidation number (or state) of the ions in the liquid electrodes changes, the VIB internal resistance must be measured against the OCV for proper battery control. Theoretically, the OCV and SOC can be matched at a 1:1 ratio, and the internal resistance of the VIB can be obtained by measuring the OCV.

[0101] In step (i) of this basic procedure, the length or interval of the time interval or region can be varied as needed, but the cycle must not be too fast. For example, a cycle of 10 to 20 Hz may be deemed too short or too fast for accurate measurements. That is, the time interval or region must be long enough to allow current initialization and IR drop measurements to be performed, so that OCV confirmation can be performed as accurately as possible. In a preferred method for at least one embodiment, the minimum interval is 0.1 seconds, allowing current initialization and necessary measurements to be performed.

[0102] When the time interval is relatively short, the data values ​​of the resistance vs. OCV curve have a high density, resulting in more accurate results. High accuracy requires calculation / measurement processing power and time, so there is a trade-off between these two. For example, procedures such as current initialization can be burdensome, but if a highly accurate battery control voltage interval is necessary and important, it is possible to set as many time intervals as necessary and perform measurements and calculations such as current initialization. On the other hand, if overall system operational stability is a higher priority, it is also possible to minimize the number of current initializations and identify the battery control voltage interval.

[0103] In step (ii) of the basic procedure of this embodiment, the IR drop can be measured by various methods. Here, the IR drop may be measured for all time intervals, or only for a specific interval. For example, since the region with the inflection point in the resistance vs. OCV curve is important, the IR drop may be measured only in this region. Furthermore, if more IR drop measurements are required, the IR drop may also be measured for regions other than the inflection point.

[0104] FIG. 9 is an exemplary diagram showing two contrasting situations of battery cell resistance and IR drop occurring at inflection points during charging or discharging according to at least one embodiment of the present invention.

[0105] 9, the first data value 920 indicates a case where the battery cell resistance is high, and there is a large IR drop at or near the inflection point during charging and discharging. On the other hand, the second data value 910 indicates a case where the battery cell performance is better, and there is a small IR drop at or near the inflection point during charging and discharging. In this way, the battery performance can be compared and determined.

[0106] There is a trade-off between the frequency of IR drop measurements and the time and processing involved. For example, referring again to Figure 9, the experimental methodology shows IR drop measurements being performed every minute. However, it may be determined that minute-by-minute IR drop measurements are not necessary at the beginning and end of the experiment, and measurements could be performed every three minutes, for example. On the other hand, if more precise measurements are required at or around the inflection point, measurements may need to be performed at shorter intervals, such as every 30 seconds or every 5 seconds, to identify the point where IR drop suddenly changes. To address this trade-off, specific VIB or battery characteristics, such as battery capacity, overall size, commercial application, operating environment, charging / discharging time (daytime or nighttime), manufacturing costs, and operating costs, can be considered.

[0107] The basic procedure used in this embodiment to set a voltage range suitable for battery control will now be described in more detail.

[0108] The present inventors have recognized that, during battery control, ohmic loss can be effectively reduced or minimized by setting a voltage range suitable for an operating region in which the battery's internal resistance is relatively low, and further, that this voltage range can be appropriately adjusted based on changes in the amount of current during battery charging and discharging.

[0109] In the prior art, there was no concept that the voltage range should be adjusted according to the change in the amount of current. Therefore, after thorough research and development, the inventors have concluded that the lack of proper adjustment of the conventional voltage range is the cause of the reduced efficiency of conventional charging and discharging operations. That is, the inventors have recognized that in the conventional method, when a current below a certain level is applied to the battery, the charging and discharging efficiency of the battery decreases. Based on this recognition, the inventors have proposed an effective solution according to the embodiments described herein.

[0110] FIG. 10 is an exemplary diagram showing an experimental result of determining the end discharge voltage using a pulsed galvanostatic measurement curve and an internal resistance curve at a high current density according to at least one embodiment of the present invention.

[0111] Referring to FIG. 10, the results of an experiment conducted using a pulsed galvanostatic measurement curve and a battery internal resistance curve to determine the end discharge voltage at a high current density are shown: (a) 20 mA g -1 , (b) 50mA g -1 , (c) 100mA g -1 , (d) 200mA g -1 An exemplary result is shown for the case

[0112] The experimental results show that by utilizing the system the inventors have focused on, it is possible to set an optimized voltage range, and the charging and / or discharging operation of the battery can be dramatically improved compared to conventional charging and discharging methods.

[0113] However, all batteries are subject to various conditions due to their electrochemical characteristics, such as variations in the surrounding environment and internal ionic configuration. Furthermore, there are only a limited number of values ​​that can be measured within a certain period of time without damaging or destroying the battery. Typical values ​​include voltage, current (resistance), and impedance depending on frequency. For lithium batteries and some lead-acid batteries, impedance measurement is used to evaluate the battery's lifespan and capacity.

[0114] For vanadium batteries like VIBs, DC current and voltage measurements are generally sufficient to cover most of the phenomena seen in impedance measurements. The lack of effectiveness of impedance measurements is presumably due to the liquid electrodes in the VIBs. The correlation between each measurement value (current, voltage, and resistance) fluctuates significantly depending on factors such as temperature. Furthermore, the average voltage measured by external devices changes depending on the ion distribution in the liquid electrodes inside the VIBs.

[0115] Therefore, the present inventors recognized the need for "standardization" (or standardization, systemization, control, unification, harmonization, etc.) of the state, condition, or specification of batteries such as VIBs due to temperature, ion distribution, etc., and decided to make it the standard for voltage measurement. As a result, the present inventors discovered that by utilizing this standardized state or condition, more accurate voltage measurement is possible, and that this can be applied to improving the charging and / or discharging operation of batteries such as VIBs.

[0116] The following provides additional technical background to aid in understanding the concepts and embodiments that the inventors have focused on.

[0117] The present inventors discovered the following peculiar phenomenon during the VIB experiment. In the CC-CV curve, the OCV decreases at the same SOC as the charge amount corresponding to the CV increases. That is, the OCV decreases when the charge / discharge current is small or the charge / discharge time is long.

[0118] According to conventional theory, OCV is a value measured when the current is 0, and therefore it was thought that it would not change depending on the amount of current.

[0119] FIG. 11 is an exemplary diagram illustrating the relationship of open circuit voltage (OCV) to state of charge (SoC) for a short charge period, a long charge / discharge period, and a short discharge period in accordance with at least one embodiment of the present invention.

[0120] Based on this relationship, the inventors have recognized that there is a transient element in the actual charging and discharging process of a battery, and that a specific method or condition is required for this element to reach saturation.

[0121] The present inventors have determined that the above-mentioned phenomenon is caused by the following reasons. In a vanadium-based battery such as a VIB or VRFB, the battery casing is the container for one battery cell, and the inside is divided into two by a separator. The first half-cell for the cathode contains a liquid electrode and has a solid electrode arranged along its inner wall, and the second half-cell for the anode also contains a liquid electrode and has a solid electrode arranged along its inner wall.

[0122] The battery reaction in a VIB (or VRFB) with this structure mainly occurs on the surface of the carbon fiber of each solid electrode, for reasons that will be explained in more detail below.

[0123] The liquid electrode of the VIB is a strongly acidic liquid containing a large number of proton ions. These protons can move and permeate through the separator membrane to maintain the electrical balance of the liquid electrode. Furthermore, during charging and discharging, the ion distribution near the surface of the carbon fiber of each solid electrode differs from the ion distribution inside the liquid electrode, which is farther from the carbon fiber of the solid electrode. This is because externally supplied electrons flow along the carbon fiber, causing ion changes at its surface. As a result, the vanadium ions in the liquid electrode have different oxidation numbers (or oxidation states) depending on their distance from the carbon fiber of the solid electrode.

[0124] For example, during charging, the oxidation number of vanadium ions adjacent to the solid electrode surface on the cathode side approaches +2, while the oxidation number of vanadium ions farther from the solid electrode approaches +3. On the other hand, during charging, the oxidation number of vanadium ions adjacent to the solid electrode surface on the anode side approaches +5, while the oxidation number of vanadium ions farther from the solid electrode approaches +4. During discharging, the opposite occurs on the cathode and anode sides.

[0125] During charging and discharging, the electrochemical (and / or conductive) battery reaction proceeds first in the region of the solid electrode that contacts the carbon fiber surface, i.e., the near-fiber region, after which additional ions diffuse or disperse due to electromagnetic effects caused by ion diffusion and / or electrical imbalance.

[0126] When a battery is subjected to constant current (CC) control, a constant current (of the same potential) is applied to the solid electrode. Measuring the battery's OCV is equivalent to measuring the potential / voltage concentrated on the solid electrode surface. In other words, measuring the OCV of a VIB externally corresponds to the voltage present in the fiber-adjacent area. However, because the optimized voltage range used for battery control during charge and discharge requires determining the "average SoC" of the overall battery operation, which requires measurement, calculation, or estimation of specific OCV-SOC relationships, simple external measurement of OCV is not sufficiently accurate for vanadium-based batteries such as VIBs. In other words, because the overall battery capacity of a VIB is calculated by multiplying the "average SoC" by the capacity of the liquid electrodes within the VIB, it is impossible to achieve the desired battery control simply by measuring the OCV externally without considering other variables and conditions.

[0127] Ultimately, because vanadium-based redox batteries such as VIBs use liquid electrodes, the technical considerations and requirements for battery charge and discharge operation are entirely different from those for non-redox batteries such as lithium-based batteries and lead-acid-based batteries. Therefore, the present inventors have recognized that additional conditions and factors must be considered when setting an optimized voltage range for controlling the charge and discharge of vanadium-based redox batteries such as VIBs.

[0128] However, the condition of a battery is also significantly affected by the ambient or environmental temperature. Therefore, the inventors have recognized that for a desirable battery evaluation, the ambient temperature must be kept relatively constant. See, for example, the following:

[0129] Understanding the effect of ambient temperature on battery efficiency is important, especially in the operation of energy storage systems (ESS).

[0130] FIG. 12 is an exemplary diagram illustrating the influence of ambient temperature on a vanadium-based battery (VIB) according to at least one embodiment of the present invention.

[0131] Referring to FIG. 12, the energy efficiency of the VIB at various environmental temperatures is examined, where (a) shows the energy efficiency and (b) shows the Coulombic efficiency.

[0132] The environmental temperature was set in the range of -15°C to 50°C, and the energy efficiency was measured under the condition of 1 discharge rate (C-rate).

[0133] The definition of discharge rate, as known in the battery industry, is: C-rate = (Maximum battery capacity: Wh) / (Maximum battery charge or discharge time: h) In other words, 1C means the output when the battery is consumed in 1 hour.

[0134] These measurement results showed that the optimum temperature range for achieving the highest energy efficiency of approximately 98.1% was approximately 25°C to 35°C. When the temperature exceeded 40°C, energy efficiency decreased slightly, which was thought to be due to a decrease in Coulomb efficiency. The VIB uses liquid electrodes, and it was thought that the higher the temperature, the more active the phenomenon of the cathode and anode liquid electrodes mixing through the separation membrane became. However, even at 50°C, energy efficiency remained at a high level of approximately 97.3%.

[0135] The decline in energy efficiency was more pronounced at low temperatures. At relatively low temperatures, the viscosity of the liquid electrode increases, slowing the chemical reaction, reducing the charge transfer rate and the diffusion rate of vanadium ions. Between temperatures of approximately 25°C and 0°C, the decline in energy efficiency was gradual, reaching 94.9% at 0°C. However, the decline in energy efficiency became more pronounced below 0°C, dropping to approximately 84.3% at -15°C. Applying heat to the battery causes the energy storage system (ESS) to consume its own energy, reducing the overall energy efficiency of the ESS. However, considering the battery alone, its energy efficiency can be improved by heating or maintaining an appropriate temperature. Therefore, efficient ESS operation requires a thorough understanding and control of the relationship between battery performance and operating temperature.

[0136] Based on the technical matters and charge / discharge performance described above, the inventors have considered how batteries should be evaluated, and have conducted research and development activities on means for eliminating or suppressing the adverse effects of current fluctuations during battery charge / discharge, and means for dealing with the effects of environmental temperature on the control or operation of the battery.

[0137] As a result, we propose that when evaluating vanadium-based batteries such as VIBs and VRFBs, we present so-called "standard conditions" and conduct tests only under those conditions. These "standard conditions" can be applied not only to the evaluation of specific batteries, but also to quality control (QC), analysis of system abnormalities, recycling, etc.

[0138] The energy efficiency measurements under the conditions of 1 discharge rate in the ambient temperature range of -15°C to 50°C described above can be said to be the optimal discharge rate (C-rate) conditions that the inventors have identified through research and development and various tests. However, the inventors have confirmed that conditions of 0.5 C-rate or higher, or conditions in the range of 0.5 to 1.5 C-rate, are also included in the examples of the present invention. The specific C-rate values ​​and ranges described above are presented because experimental results may be unsatisfactory if the C-rate values ​​or ranges are outside these values.

[0139] The "standard conditions" presented here refer to the conditions under which a battery is evaluated (1) at a constant temperature, (2) within a specific voltage range, and (3) after waiting for it to reach equilibrium, and the evaluation is carried out under such "standard conditions."

[0140] Furthermore, as a rule, SoC estimation should be performed under standard conditions. Values ​​measured externally are affected by temperature and instantaneous current, so accurate SoC measurement is possible by eliminating these factors.

[0141] FIG. 13 is an exemplary flow chart illustrating a procedure for entering a standard state of a vanadium-based battery in accordance with at least one embodiment of the present invention.

[0142] In step S1501, the vanadium battery enters the standard state.

[0143] In step S1503, the OCV is measured as shown in the figure, and specifically, at least one of the voltage drop (IR drop) and the voltage rise (IR rise) can be measured (S1513). During such measurements, the VIB is maintained in a standard state (S1512).

[0144] Specifically, in step S1511 after the preceding step S1501, a constant temperature to be used for OCV measurement is set.

[0145] Furthermore, a plurality of voltage values ​​are set for a specific voltage section used for OCV measurement (S1511), and as shown in step S1512, the standard state of the vanadium battery is continued during OCV measurement.

[0146] This allows at least one resistance value of the vanadium battery to be obtained (S1505), which is compared with a normal resistance value (S1507), and the state of the vanadium battery can be estimated based on the difference between the obtained resistance value and the normal resistance value (S1509).

[0147] FIG. 14 is a conceptual diagram of an exemplary apparatus capable of implementing the procedure of FIG.

[0148] The energy storage device includes an energy storage element 1601 including a battery, and controllers 1605 and 1603. The energy storage device can be configured as a battery pack including multiple battery modules and a module BMS responsible for the battery management functions of each battery module.

[0149] The energy storage device may include a pack battery management system (Pack BMS) that manages the charging and discharging of the energy storage element 1601. Furthermore, the energy storage device may optionally include a power management system (PMS) and a power conversion system (PCS). When the energy storage device includes both a PMS and a PCS, it may be referred to as an integrated ESS.

[0150] Depending on the configuration of the energy storage device, the PMS and PCS may be physically separated from the energy storage device and configured as independent devices. The PMS and PCS can operate as independent devices and can exchange information and control the operation of the energy storage device through communication with the energy storage device.

[0151] As shown, the energy storage element 1601 of the energy storage device includes one or more battery modules, and the energy storage device may include a module BMS that manages the battery modules. One example of the energy storage element 1601 includes a battery pack configured of one or more sets of battery modules and module BMSs.

[0152] The battery of the energy storage element 1601 can be charged with power via the PCS. The PCS can receive power and store it in the battery or release it to the grid. In this process, the PCS can perform AC / DC conversion or convert the input and output voltages, frequencies, etc.

[0153] The PMS communicates with the PCS to exchange information and can provide the PCS with information necessary for charging, discharging, and controlling the battery.

[0154] The module BMS monitors the battery's state of charge, state of discharge, temperature, voltage, current, etc., and manages the battery. The pack BMS is a battery management system for the entire battery pack.

[0155] The controllers 1605, 1603 can utilize power measurements in the power domain to determine charging or discharging of the energy storage element 1601. Also, according to one embodiment, the controllers 1605, 1603 can be integrated with the PMS and operate as one component.

[0156] According to one embodiment of the invention, controllers 1605, 1603 may be provided as separate components. According to another embodiment of the invention, controllers 1605, 1603 may be embodied within a PMS, which may provide the functionality of the controllers described herein.

[0157] 13 for evaluating a vanadium-based redox battery, the energy storage device may include a device including: a setting element configured to set at least one standard condition related to the redox battery used in the method for evaluating the redox battery; and a measurement element configured to perform one or more measurements on the redox battery according to the set standard condition, where the standard condition includes a certain temperature, multiple voltage values ​​for a specific voltage range, and a standard state of the redox battery. For example, at least one of the setting element and the measurement element may be embodied in the controller 1603, the PMS, or the module BMS. The setting element and the measurement element may also be embodied in hardware, software, or a combination thereof.

[0158] On the other hand, the area 1605 shown in dotted lines that is responsible for battery management control can be seen as the battery management element 1603 of the energy storage system (ESS).

[0159] The battery management element 1603 is operatively connected to an energy storage element 1601. The energy storage element 1601 includes a battery pack made up of a plurality of battery cells (cell 1, ..., cell n) to which a discharge is connected.

[0160] The battery management element 1603 includes a measurement unit that measures various values ​​(such as temperature 1, temperature 2, current, V1, and Vn) from the energy storage element 1601, and a battery capacity estimation unit, a charge state unit, a health state unit, and a temperature management unit are connected to the measurement unit and can perform their respective operations. The battery management element 1603 may also include a cell balancing unit that performs cell balancing on the battery pack according to the measurement results of the measurement unit. Finally, the battery management element 1603 may include a connection control unit that manages connections with other elements such as a CAN bus control unit.

[0161] FIG. 15 is a conceptual diagram of an exemplary semiconductor chip structure in accordance with at least one embodiment of the present invention.

[0162] The hardware responsible for managing or controlling the battery may be embodied in the form of a printed circuit board (PCB) 1610, which may include a semiconductor chip structure or a combination thereof, and the semiconductor chip, semiconductor chip combination, or semiconductor chip structure may include a memory 1612 or similar storage unit and a processor 1614 or similar control unit. Such battery management / control hardware may be embodied, together with software, firmware, etc. as needed, to perform the procedures and features described in the embodiments of the present invention.

[0163] How to apply the standard cycle Some or all of the features described in at least one embodiment of the present invention may be related to various specifications, standards, and / or requirements that have been established, are currently being promoted, or will be promoted in the future by the battery industry and / or related groups, associations, agencies, etc.

[0164] That is, the contents described in this specification are believed to be related to the performance and safety of redox batteries, vanadium-based batteries, vanadium-ion batteries (VIBs), etc. for energy storage systems (ESSs). One object of the present invention is to provide a method and apparatus for performing various measurements necessary to confirm the operating state of a vanadium-based redox battery according to its unique technical characteristics in order to evaluate the battery, which may be reflected in related specifications, standards, and / or requirements.

[0165] It is believed that the present invention and the matters described herein may be relevant to the following codes and / or standards:

[0166] KS C IEC 62619: Secondary cells and batteries containing alkaline or other non-acid electrolytes - Safety requirements for industrial lithium secondary cells and batteries.

[0167] Of course, the above-mentioned standards are just a few examples, and IEC-related standards in particular contain basic technical content and may have close ties with new standards that will be established in the future.

[0168] Hereinafter, using features according to embodiments of the present invention, a description will be given of pre-test preparation conditions, standard cycles, test procedures, standard charging, and standard discharging in performance and safety testing / confirmation, etc. Basically, recognizing that "standardization" (or standardization, systematization, regulation, unification, harmonization, etc.) is necessary for battery states, conditions, or specifications, the inventors have found that by using such standardized states or conditions, more accurate voltage measurement is possible and can be applied to improving the charging and / or discharging operations of batteries such as VIBs, which can be applied to performance and safety testing / confirmation, etc.

[0169] Unless otherwise specified in the standard, the pre-test preparation conditions are as follows: The monoblock battery, module, or battery system, which is the first sample received, is fully discharged before electrical testing as follows: A standard cycle is performed in which the monoblock battery, module, or battery system is charged at ambient temperature (25±5°C) to the end-of-charge voltage or end-of-charge conditions according to the method specified by the manufacturer, and then discharged to the end-of-discharge voltage or end-of-discharge conditions. The purpose of the standard cycle is to maintain the same initial state for each test of the monoblock battery, module, or battery system. In the case of a redox battery (VIB) according to one embodiment of the present invention, a standard cycle can be performed to conform to at least some of the standardized conditions described above.

[0170] As a test procedure, it is proposed that the first sample be subjected to a standard cycle at ambient temperature (25±5°C) a predetermined number of times, preferably three times. The standard cycle is performed in the following order: standard charge and standard discharge. In a preferred embodiment of the present invention, if, for some reason, the time interval between the end of the first standard cycle and the start of the second standard cycle is greater than or equal to the first period, it is proposed to repeat the standard cycle an additional number of times in addition to the predetermined number of times. Preferably, the first period is set to three hours. For example, if the time interval between the end of the standard cycle or between tests exceeds three hours, the standard cycle can be repeated, with one cycle being the standard for the first sample. In the case of a VIB according to one embodiment of the present invention, as described with reference to FIG. 11, it is proposed to perform the standard cycle a predetermined number of times depending on the characteristics of the VIB, i.e., the electrochemical characteristics of the vanadium material, the distribution of vanadium ions in the liquid electrode, and the oxidation number / state of the vanadium ions. This may also be related to the characteristics of the VIB structure described with reference to FIGS. 2 to 4.

[0171] To perform standard charging, the standard charging current provided by the manufacturer, equivalent to a 0.5C-rate, can be used. The charging procedure and end-of-charge criteria should be applied according to the manufacturer's specifications and should include a time limit for the overall charging process. The charging procedure involves charging to the end-of-charge voltage using a predetermined standard charging current and the method provided by the manufacturer. The rest period after charging, which is required to reach a steady state, is preferably set to a period shorter than the first period, and different settings are suggested depending on the battery type. Specifically, in one embodiment of the present invention, the rest period can be set to within one hour for monoblock batteries and within two hours for modules and battery systems. In the case of a VIB according to one embodiment of the present invention, specific standard charging currents, charging procedures, end-of-charge criteria, charging time, steady state, rest periods, etc. can be set based on the electrochemical properties of the vanadium material, the distribution of vanadium ions in the liquid electrode, and the oxidation number / state of the vanadium ions.

[0172] To perform standard discharge, the manufacturer's recommended discharge current equivalent to a 0.5C-rate can be used. The discharge procedure involves discharging at a predetermined standard discharge current until the manufacturer's recommended discharge end voltage is reached. The rest period after discharge until a stable state is reached is within one hour for monoblock batteries and within two hours for modules and battery systems. In the case of a VIB according to one embodiment of the present invention, specific standard discharge currents, discharge procedures, discharge end determination, discharge time, stable state, rest periods, etc. can be determined and implemented based on the electrochemical properties of the vanadium material, the distribution of vanadium ions in the liquid electrode, and the oxidation number / state of the vanadium ions.

[0173] FIG. 16 is a conceptual diagram of an exemplary battery management system in accordance with at least one embodiment of the present invention.

[0174] The battery management system 1800 includes a charging component 1802, a measuring component 1804, and an acquisition component 1806, each of which may be functionally and / or physically connected to one another.

[0175] The charging element 1802 can charge the vanadium-based battery (temporarily or instantaneously) to a specific charge rate (C), i.e., for example, a C-rate in the range of 0.5C to 1.5C, while the vanadium-based battery is maintained in a standard state, and can also perform fast charging. The measuring element 1804 can measure at least one of a voltage drop (IR drop) and a voltage rise (IR rise) for the vanadium-based battery charged by the charging element 1802. The acquiring element 1806 can acquire one or more resistance values ​​of the vanadium-based battery using at least one of the IR drop and IR rise.

[0176] By using the battery management system 1800 configured in this manner, the resistance value can be used to check the operating state of the vanadium-based battery or an energy storage unit embodied in the form of a cell or pack of multiple vanadium-based batteries.

[0177] In at least some embodiments, the battery management system 1800 may be applied to at least one of the components shown in Fig. 14. That is, at least some of the functions and / or components of the battery management system 1800 may be applied to at least one of the pack BMS, PMS, PCS, controller, and / or module BMS, or the functions or components may be divided and embodied in two or more components.

[0178] In at least some embodiments, the battery management system 1800 may be implemented in the form of a printed circuit board (PCB) 1610 or the like as hardware responsible for battery management or control as shown in FIG. 15 above, which may include a semiconductor chip structure or combination.

[0179] FIG. 17 is a conceptual diagram of an exemplary device in accordance with at least one embodiment of the present invention.

[0180] The apparatus 1900 includes a first module 1902 and a second module 1904 operatively connected to a processor 1906 to receive instructions or commands.

[0181] The first module 1902 is responsible for maintaining the equilibrium state of the vanadium-based battery, and the second module 1904 can measure voltage changes, including at least one of voltage drop (IR drop) and voltage rise (IR rise), after charging the vanadium-based battery to a specific charge rate (C) (i.e., C-rate), for example, in the range of 0.5C to 1.5C.

[0182] The processor 1906 is operatively connected to the first module 1902 and the second module 1904 and can provide control to obtain one or more resistance values ​​of the vanadium based battery using at least one of the IR drop and the IR rise and to ascertain the operating status of the vanadium based battery.

[0183] In at least some embodiments, the apparatus 1900 may be applied to at least one of the components of Fig. 14. That is, at least some of the functions and / or components of the apparatus 1900 may be applied to at least one of the pack BMS, the PMS, the PCS, the controller, and / or the module BMS, or the functions or components may be divided and embodied in two or more components.

[0184] In at least some embodiments, such device 1900 may be embodied in the form of a printed circuit board (PCB) 1610 or the like as hardware responsible for battery management or control of FIG. 15, which may include a semiconductor chip structure or combination.

[0185] The features of the embodiment of the present invention can also be explained as follows. According to an embodiment of the present specification, there is provided a battery management system including: a charging element that charges a redox battery at 0.5 C-rate or more while the redox battery is maintained in a standard state; a measuring element that measures at least one of a voltage drop (IR drop) and a voltage rise (IR rise) for the redox battery charged by the charging element; and an acquiring element that acquires one or more resistance values ​​of the redox battery using at least one of the IR drop and the IR rise, and these resistance values ​​are used to confirm the operating state of the redox battery or an energy storage unit in which multiple redox batteries are embodied in the form of a cell or a pack.

[0186] The acquisition element further performs the steps of: comparing the acquired resistance value of the redox battery with a normal resistance value of the redox battery; and estimating the state of the redox battery based on the difference between the acquired resistance value and the normal resistance value.

[0187] The present invention further includes a maintenance element that performs the steps of setting a constant temperature for performing an open circuit voltage (OCV) measurement, setting a plurality of voltage values ​​in a specific voltage range for performing the open circuit voltage (OCV) measurement, and maintaining a balanced state of the redox battery while performing the open circuit voltage (OCV) measurement.

[0188] To measure the open circuit voltage (OCV), the charging element charges the redox battery at 1C-rate, and the maintaining element sets a constant temperature at room temperature, a charge start voltage of 1.2V, and at least one voltage greater than 1.2V within the voltage range.

[0189] Maintaining the equilibrium state of the redox battery includes the steps of charging the redox battery to a specific charge level using a set voltage based on the voltage value, performing constant voltage (CV) charging until a charge level corresponding to a very small current is reached, and measuring the open circuit voltage (OCV) after the constant voltage (CV) charging.

[0190] The specific voltage section is used when charging or discharging the redox battery, and the specific voltage section is specifically set in consideration of a voltage change that accompanies a change in the amount of current during charging or discharging of the redox battery.

[0191] Furthermore, according to an embodiment of the present specification, there is provided an apparatus comprising: a first module for maintaining an equilibrium state of a vanadium-based redox battery; a second module for measuring a voltage change including at least one of a voltage drop (IR drop) and a voltage rise (IR rise) after charging the vanadium-based redox battery at a C-rate range of 0.5 to 1.5; and a processor operatively connected to the first module and the second module, for obtaining one or more resistance values ​​of the vanadium-based redox battery using at least one of the IR drop and the IR rise, and for providing control to confirm the operating state of the vanadium-based redox battery.

[0192] The processor further performs the steps of: comparing the acquired resistance value of the vanadium-based redox battery with a normal resistance value of the vanadium-based redox battery; and estimating the state of the vanadium-based redox battery based on the difference between the acquired resistance value and the normal resistance value.

[0193] The processor utilizes the measured resistance of the vanadium-based redox battery to evaluate at least one of the battery cell and one or more internal battery elements.

[0194] The processor provides control to perform the steps of setting a constant temperature for performing an open circuit voltage (OCV) measurement to maintain a balanced state of the vanadium-based redox battery, setting a plurality of voltage values ​​in a specific voltage interval for performing the open circuit voltage (OCV) measurement, and maintaining a balanced state of the vanadium-based redox battery while performing the open circuit voltage (OCV) measurement.

[0195] To measure the open circuit voltage (OCV), the processor fast charges the vanadium-based redox battery at a 1C-rate, and the maintaining element sets a constant temperature to room temperature, and sets a charge start voltage to 1.2 V and at least one voltage greater than 1.2 V within the voltage range for the voltage value.

[0196] The processor controls the vanadium-based redox battery to be charged to a specific charge level using a set voltage based on the voltage value in order to maintain an equilibrium state of the vanadium-based redox battery, to perform constant voltage (CV) charging until a charge level corresponding to a very small current is reached, and to measure the open circuit voltage (OCV) after the constant voltage (CV) charging.

[0197] The specific voltage section is used when charging or discharging the vanadium-based redox battery, and the specific voltage range is specifically set in consideration of a voltage change caused by a change in the amount of current during charging or discharging of the vanadium-based redox battery.

[0198] Furthermore, according to an embodiment of the present specification, there is provided a method for evaluating the operating state of a vanadium-based battery, comprising the steps of: maintaining an equilibrium state of the vanadium-based battery; and measuring a voltage change including at least one of a voltage drop (IR drop) and a voltage rise (IR rise) after temporarily charging the vanadium-based battery at a specific charge rate (C-rate), wherein at least one of the IR drop and the IR rise is used to obtain one or more resistance values ​​of the vanadium-based battery and confirm the operating state of the vanadium-based battery.

[0199] The method further includes the steps of: comparing the obtained resistance value of the vanadium battery with a normal resistance value of the vanadium battery; and estimating the state of the vanadium battery based on the difference between the obtained resistance value and the normal resistance value.

[0200] The measured resistance of the vanadium-based battery is used to characterize at least one of the battery cell and one or more internal battery elements.

[0201] In order to maintain the equilibrium state of the vanadium-based battery, the steps of setting a constant temperature for performing an open circuit voltage (OCV) measurement, setting a plurality of voltage values ​​in a specific voltage range for performing the open circuit voltage (OCV) measurement, and maintaining the equilibrium state of the vanadium-based battery during the open circuit voltage (OCV) measurement are performed.

[0202] To measure the open circuit voltage (OCV), the specific charge rate is 0.5 C-rate or more, the maintaining element sets the constant temperature to room temperature, and the voltage value to a charge start voltage of 1.2 V and at least one voltage greater than 1.2 V within the voltage range.

[0203] In order to maintain the equilibrium state of the vanadium battery, the vanadium battery is charged to a specific charge level using a set voltage based on the voltage value, and constant voltage (CV) charging is performed until a charge level corresponding to a very small current is reached, and after the constant voltage (CV) charging, the open circuit voltage (OCV) is measured.

[0204] The specific voltage range is used when charging or discharging the vanadium battery, and the specific voltage section is specifically set in consideration of a voltage change caused by a change in the amount of current during charging or discharging of the vanadium battery.

[0205] Furthermore, according to an embodiment of the present specification, there is proposed a method for evaluating the operating state of a vanadium-based redox battery, comprising the steps of: charging a cell, module, battery pack, or battery system at room temperature (25±5°C) with a current equivalent to a standard charging current of 0.5C to a charge end voltage specified by the battery manufacturer or a relevant organization; and discharging the cell, module, battery pack, or battery system at room temperature (25±5°C) with a current equivalent to a standard discharging current of 0.5C to a discharge end voltage specified by the battery manufacturer or a relevant organization, and performing standard cycles of standard charging and standard discharging so as to maintain the same initial state for each test for evaluating the operating state.

[0206] The above method may further include the steps of: waiting for a rest time of 2 hours or less after charging until a stable state is reached; and waiting for a rest time of 2 hours or less after discharging until a stable state is reached.

[0207] In the case of the vanadium-based redox battery, the stable state and the rest time can be determined based on the electrochemical properties of the vanadium material, the distribution state of the vanadium ions in the liquid electrode, the oxidation number / state of the vanadium ions, etc.

[0208] The standard cycle of standard charge and standard discharge can be performed at least three times. In order to maintain the equilibrium state of the vanadium-based redox battery, the vanadium-based redox battery is temporarily charged at a specific charge rate (C-rate), and then a voltage change including at least one of a voltage drop (IR drop) and a voltage rise (IR rise) is measured, and one or more resistance values ​​of the vanadium-based redox battery can be obtained using at least one of the IR drop and the IR rise.

[0209] To maintain the equilibrium state of the vanadium-based redox battery, a certain temperature can be set for measuring the open circuit voltage (OCV), and a voltage value in a specific voltage range can be set for measuring the open circuit voltage (OCV).

[0210] The specific voltage section may be specifically set in consideration of a voltage change that accompanies a change in the amount of current during charging or discharging of the redox battery.

[0211] Although all components constituting the embodiments of the present invention are described as being combined together or operating in combination, this does not necessarily mean that the present invention is limited to this embodiment. All components may be selectively combined and operate in one or more combinations within the scope of the present invention. Furthermore, all components may be embodied as individual pieces of hardware, or some or all of the components may be selectively combined and embodied as a computer program having program modules that perform some or all of the functions combined in one or more pieces of hardware. The codes and code segments constituting such a computer program would be easily inferred by those skilled in the art. Such a computer program may be stored in a computer-readable storage medium and read and executed by a computer to implement an embodiment of the present invention. Examples of storage media for computer programs include recording media such as magnetic recording media, optical recording media, and semiconductor recording devices. Furthermore, a computer program embodying an embodiment of the present invention may include a program module transmitted in real time via an external device.

[0212] It should be understood that the above-described embodiments are illustrative in all respects and are not limiting, and the scope of the present invention is defined by the claims set forth below rather than the above detailed description. Furthermore, the meaning and scope of the claims, as well as all modifications and variations derived from the equivalent concepts thereof, should be construed as being included in the scope of the present invention. [Industrial Applicability]

[0213] The present invention can be utilized as a method and apparatus for checking the operating state of various batteries, particularly redox batteries.

Claims

1. 1. A method for evaluating the operating state of a vanadium ion battery, comprising: a standard cycle including charging one or more of the vanadium ion battery cells, a monoblock including one or more of the cells that can be connected in series or parallel, a module in which one or more of the monoblocks are connected in series or parallel, a battery pack or a battery system including one or more of the monoblocks or modules to a charge end condition within a predetermined temperature range, and subsequently discharging to a discharge end condition, repeated a predetermined number of times; The vanadium ion battery cell comprises: a first electrode at which a first half-reaction of vanadium ions in a first electrolyte takes place; a second electrode at which a second half-reaction of vanadium ions in a second electrolyte takes place; a separator disposed between the first electrode and the second electrode; and a frame supporting the separation membrane Including, and when a time interval between an end of a first standard cycle and a start of a second standard cycle is equal to or greater than a first period during the standard cycles repeated a predetermined number of times, further repeating the standard cycles corresponding to an additional number of times in addition to the predetermined number of times.

2. a rest period between charging and discharging in the standard cycle that is shorter than the first period; 2. The method for evaluating the operating state of a vanadium ion battery according to claim 1, wherein the rest period corresponds to a second period for the monoblock and a third period longer than the second period for the module, the battery pack, and the battery system.

3. a rest period between the discharging of the first standard cycle and the charging of the second standard cycle that is shorter than the first period; 2. The method for evaluating the operating state of a vanadium ion battery according to claim 1, wherein the rest period corresponds to a second period for the monoblock and a third period longer than the second period for the module, the battery pack, and the battery system.

4. The vanadium ion battery is 2. The method for evaluating the operating state of a vanadium ion battery according to claim 1, wherein the first electrolyte and the second electrolyte are configured to self-circulate without the operation of a pump.

5. The method for evaluating the operating state of a vanadium ion battery according to claim 1 , wherein the cells of the vanadium ion battery are shielded through the frame.

6. 2. The method for evaluating the operating state of a vanadium ion battery according to claim 1, wherein the charging and discharging in the standard cycle are performed at a current corresponding to a 0.5 C-Rate.

7. 2. The method of claim 1, wherein the standard cycle is performed to maintain the same initial condition for each test.

8. The method for evaluating the operating state of a vanadium ion battery according to claim 1 , wherein the predetermined number of times is set to three or more times.

9. The method for evaluating the operating state of a vanadium ion battery according to claim 1 , wherein the predetermined temperature range is set within an error range of 5° C. to 25° C.

10. In a system for evaluating the operating state of a vanadium ion battery, a system for charging one or more of the vanadium ion battery cells, monoblocks including one or more of the cells that can be connected in series or parallel, modules in which one or more of the monoblocks are connected in series or parallel, and battery packs or battery systems including one or more of the monoblocks or modules to a charge end condition within a predetermined temperature range, and discharging the charging to a discharge end condition after the charging; The vanadium ion battery cell comprises: a first electrode at which a first half-reaction of vanadium ions in a first electrolyte takes place; a second electrode at which a second half-reaction of vanadium ions in a second electrolyte takes place; a separator disposed between the first electrode and the second electrode; and a frame supporting the separation membrane; The system comprises: and if, during the standard cycles repeated a predetermined number of times, a time interval between the end of a first standard cycle and the start of a second standard cycle is equal to or greater than a first period, further repeating the standard cycles corresponding to an additional number of times in addition to the predetermined number of times.

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