Secondary battery management system and management method

Abstract

An embodiment of the present invention relates to a method for preventing fatal problems such as thermal runaway by monitoring the internal resistance of a secondary battery cell or battery and detecting the risk of cell short circuit at an early stage. The present invention provides a secondary battery management system and method for: measuring an internal resistance value in a charging state in a predetermined cell or battery charging state; calculating an internal resistance drop value; determining whether the internal resistance drop value exceeds a preset reference value; and operating a circuit breaker if a counted number excesses exceeds a preset number.

Description

Secondary battery management system and management method

[0001] The present invention relates to a secondary battery management system, and more specifically, to a battery management system that monitors the internal resistance of a secondary battery during every charge and discharge cycle and detects the risk of internal short circuits within the cell at an early stage to prevent fatal problems such as thermal runaway, and a battery management method using the same.

[0002]

[0003] While rechargeable batteries function as essential energy storage devices in modern society, internal cell short circuits during operation can cause serious problems such as thermal runaway. These issues are frequently reported in mobile devices, electric vehicles, and energy storage systems using lithium-ion batteries, and in some cases, have led to fatal consequences.

[0004] In particular, new technologies aiming for high energy density, such as lithium-sulfur batteries, utilize metal anodes; however, cell short circuits caused by the formation of metal dendrites act as a major factor hindering commercialization. This problem is also observed in nickel-zinc (Ni-Zn) systems.

[0005] Meanwhile, internal short circuits in secondary batteries induce localized heating due to current concentration, which leads to thermal runaway and becomes a direct cause of fatal safety accidents such as fires or explosions. To date, no technology has been presented that can fundamentally prevent the occurrence of internal short circuits themselves.

[0006] Therefore, it is very important to identify the cause of short circuits occurring during the operation of cells that were initially normal, and to establish a cell / battery system to prevent short circuits and the associated safety issues. To this end, research on management systems and management devices capable of preventing short circuit problems in secondary battery cells is necessary.

[0007]

[0008] [Prior Art Literature]

[0009] [Patent Literature]

[0010] (1) Republic of Korea Registered Patent No. 10-1990042

[0011] (2) U.S. Patent No. 10302703

[0012] (3) U.S. Patent No. 11988716

[0013]

[0014] The technical problem that the present invention aims to solve is to resolve the problems of the aforementioned prior art by providing a secondary battery management system and management method that monitors the internal resistance of a secondary battery and detects the risk of cell short circuits at an early stage to prevent fatal problems such as thermal runaway.

[0015] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0016]

[0017] To achieve the above technical objectives, one embodiment of the present invention provides a secondary battery management system.

[0018] In one embodiment of the present invention, the secondary battery management system may include: a measuring unit that measures the internal resistance of a battery in a predetermined charge state for every charge / discharge cycle; a storage unit that stores the internal resistance value of the battery measured by the measuring unit; a detection unit that calculates an internal resistance drop value D according to the following Equation 1 based on the internal resistance value stored in the storage unit, accumulates and counts the number of times the calculated internal resistance drop value D exceeds a reference value d, and determines whether the counted number exceeds a preset number m to detect whether the battery has an internal short circuit; a signal unit that indicates a warning signal when the detection unit determines the battery to be in a dangerous state of an internal short circuit; and a circuit blocking unit that blocks the circuit of the battery to cut off the load on the battery when the detection unit determines the battery to be in a dangerous state of an internal short circuit.

[0019] [Equation 1]

[0020]

[0021] Here, d and m are each greater than or equal to 0 real numbers, n is the number of charge or discharge cycles, and R i (n) is the nth measured internal resistance value, and R i (n-1) represents the n-1th measured internal resistance value.

[0022] In addition, in one embodiment of the present invention, the measuring unit of the secondary battery management system may include a temperature measuring unit that corrects the internal resistance measured according to the operating temperature.

[0023] In addition, in one embodiment of the present invention, the internal resistance corrected by the temperature measuring unit can be corrected according to the following Equation 2.

[0024] [Equation 2]

[0025] R i (n) = R i o (n)exp(E a / k B T)

[0026] In the above Equation 2, R i (n) is the internal resistance value measured in the nth cycle, R i o (n) is the internal resistance corrected for temperature in the nth cycle, E a is the activation energy, k B is the Boltzmann constant, and T is the temperature.

[0027] In addition, in one embodiment of the present invention, the internal resistance corrected by the temperature measuring unit can be corrected according to the following Equation 3.

[0028] [Equation 3]

[0029] R i (n) = R i o (n)(1-bC)

[0030] In Equation 3 above, Ri(n) is the internal resistance value measured in the nth cycle, Ri o (n) is the internal resistance corrected for temperature in the nth cycle, b is the temperature coefficient, and C is the temperature in degrees Celsius.

[0031] In addition, in one embodiment of the present invention, the reference value d may be 0.05 to 0.4.

[0032] In addition, in one embodiment of the present invention, the previously set number of times m may be 3 to 20.

[0033] In addition, in one embodiment of the present invention, when the battery includes cells or units connected in parallel, the reference value d is a reference value d corrected by the following Equation 3. p It could be.

[0034] [Equation 4]

[0035]

[0036] In the above Equation 4, k is the number of parallel-connected cells or units, and d p means the corrected reference value d.

[0037] To achieve the above technical objectives, one embodiment of the present invention provides a secondary battery management method using a secondary battery management system.

[0038] In one embodiment of the present invention, a secondary battery management method using a secondary battery management system comprises: (a) an internal resistance value R when the battery is in the same charge state at a measuring unit. i (b) a step of measuring the internal resistance value R measured in step (a) and stored in the storage unit; i Based on the above, the detection unit calculates an internal resistance drop value according to the following formula 1; (c) the detection unit determines whether the internal resistance drop value D calculated in step (b) exceeds a preset reference value d, and if the calculated internal resistance drop value D is less than the reference value d, performs the process again from step (a) in the next cycle, and if it exceeds the reference value d, accumulates and counts the number of times it exceeds; and (d) if the number of times it exceeds counted in step (c) is less than a preset number m, the secondary battery management system performs the process again from step (a) in the next cycle, and if the number of times it exceeds the preset number m, the signal unit activates a battery cell or pack short-circuit warning signal and the circuit breaker unit operates a circuit breaker to cut off the battery circuit; may be included.

[0039] [Equation 1]

[0040]

[0041] Here, d and m are each greater than or equal to 0 real numbers, n is the number of charge or discharge cycles, and R i (n) is the nth measured internal resistance value, and R i (n-1) represents the n-1th measured internal resistance value.

[0042] In addition, in one embodiment of the present invention, between step (a) and step (b), (a-1) internal resistance value R iBy measuring the operating temperature, Ri according to Equation 2 or Equation 3 below o (n) further includes a step of correcting; and the corrected internal resistance value is Ri. o (n) is the internal resistance value R in step (b) above. i It can be applied as.

[0043] [Equation 2]

[0044] R i (n) = R i o (n)exp(E a / k B T)

[0045] In the above Equation 2, R i (n) is the internal resistance value measured in the nth cycle, R i o (n) is the internal resistance corrected for temperature in the nth cycle, E a is the activation energy, k B ε is the Boltzmann constant, T is the temperature, and

[0046] [Equation 3]

[0047] R i (n) = R i o (n)(1-bC)

[0048] In the above Equation 3, R i (n) is the internal resistance value measured in the nth cycle, R i o (n) is the internal resistance corrected for temperature in the nth cycle, b is the temperature coefficient, and C is the temperature in degrees Celsius.

[0049] In addition, in one embodiment of the present invention, when the battery includes cells or units connected in parallel, in step (c), the reference value d is a reference value d corrected by the following Equation 3. p It could be.

[0050] [Equation 4]

[0051]

[0052] In the above Equation 4, k is the number of parallel-connected cells or units, and d p means the corrected reference value d.

[0053] In addition, in one embodiment of the present invention, the reference value d may be 0.05 to 0.4.

[0054] In addition, in one embodiment of the present invention, the previously set number of times m may be 3 to 20.

[0055] In addition, in one embodiment of the present invention, the internal resistance value measurement may include one or more methods from the group consisting of an AC impedance method, a current step method, and a method utilizing electrochemical principles.

[0056] In addition, in one embodiment of the present invention, when the battery circuit is cut off by operating the circuit breaker in step (d), the method may further include, after step (d), a step in which a user or maintenance technician replaces the battery cell or pack, initializes the circuit breaker and the measured values, and the secondary battery management system performs the process again starting from step (a).

[0057] In addition, in one embodiment of the present invention, in step (a), the same battery charge state includes a fully charged state, a minimum charged state, or a state in which a certain amount has been charged and discharged, and may include multiple charge states within the same cycle.

[0058] In addition, in one embodiment of the present invention, when the circuit breaker operates, the load applied to the battery cell or pack may be cut off.

[0059]

[0060] A secondary battery management system according to one embodiment of the present invention can provide the effect of improving the safety of a battery cell / pack and increasing the reliability of an energy storage system by detecting a decrease in the internal resistance of the battery at an early stage and replacing it immediately without changing the current as in conventional technology, thereby eliminating problems such as fatal thermal runaway.

[0061] In addition, it can provide effects applicable to existing battery systems.

[0062] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims.

[0063]

[0064] FIGS. 1a and 1b show the metal cathode M and the electrolyte MA n This is a schematic diagram showing the movement of ions and electrons during the discharge process within a cell using [the device], and illustrating cases where metal is isolated in the electrolyte or metal is attached to the negative electrode.

[0065] Figure 2 is a graph showing the correlation between iR-drop and temperature change near room temperature as charging and discharging are repeated for a lithium-ion battery coin cell (2032 type).

[0066] Figure 3 is a graph showing the relationship between the iR value and the Celsius temperature C (iR vs. C) in a coin cell.

[0067] Figure 4 is one of the methods for measuring internal resistance, which is the process of obtaining internal resistance from the instantaneous voltage profile of a cell under current load.

[0068] Figure 5 is a flowchart of the subroutine for charging.

[0069] Figure 6 is V i This is a flowchart of the subroutine for measurement.

[0070] Figure 7 is a flowchart of the internal resistance correction subroutine according to temperature.

[0071] FIG. 8 is a diagram showing the schematic configuration of a unit for managing a cell or battery pack according to one embodiment of the present invention.

[0072] Figure 9 is a subroutine flowchart for blocking a cell, module, or the entire system.

[0073] FIG. 10 is a flowchart showing the steps of a secondary battery management method according to one embodiment of the present invention.

[0074] Figure 11 is a voltage profile of an H-type cell fabricated with two Zn electrodes and a 10 M ZnCl2 solution as an example, showing the voltage change when an internal short circuit occurs during repeated charging and discharging.

[0075] Figure 12 is a photograph of (A) the initial state, (B) the end of the first discharge, (C) the end of the first charge, and (D) the time of internal short circuit caused by deformation of the isolated metal of an H-type cell fabricated with two Zn electrodes and a 10 M ZnCl2 solution in relation to Figure 11.

[0076]

[0077] The present invention will be described below with reference to the attached drawings. However, the present invention may be implemented in various different forms and is therefore not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0078] Throughout the specification, when it is stated that a part is "connected (connected, in contact, combined)" with another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0079] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0080] Hereinafter, the present invention will be described with reference to the drawings presented in this specification. For reference, the drawings may be partially exaggerated to illustrate the features of the present invention. In such cases, it is preferable to interpret them in light of the entire intent of this specification.

[0081]

[0082] A secondary battery management system according to one embodiment of the present invention is described.

[0083] As the life cycle of a secondary battery progresses, complex structural changes occur within the cell's internal electrodes, including changes in constituent particle size, a decrease in electrolyte concentration due to chemical and electrochemical reactions, and electrolyte redistribution resulting from various forms of mass transfer. Since these changes generally increase the cell's internal resistance, polarization increases and cell performance degrades as charge and discharge cycles are repeated.

[0084] If an abnormal metal fragment is present between the anode and cathode, and the metal exhibits high reversibility for dissolution by oxidation and precipitation by reduction, and oxidation and reduction polarization occur equally within the cell electrolyte and the exchange current is sufficiently large, the internal resistance of the cell (particularly the solution resistance directly related to ion movement) can be rapidly reduced.

[0085] FIGS. 1a and 1b show the metal cathode M and the electrolyte MA n This is a schematic diagram showing the movement of ions and electrons during the discharge process within a cell using [the device], and illustrating cases where a metal is isolated in the electrolyte or attached to the negative electrode.

[0086] Referring to Figures 1a and 1b, it can be seen that some of the ion conduction pathways of the electrolyte are replaced by the electron conduction pathways of the metal, thereby reducing internal resistance, and the mechanism causing the reduction in internal resistance can be identified.

[0087] Specifically, when a metal piece M is present in the electrolyte in a state electrically isolated from the electrode, ion migration is partially replaced by electrochemical reactions at both ends, namely the precipitation of M at the anode and the dissolution of M at the cathode.

[0088] This phenomenon has been reported in the literature as bipolar electrochemistry. (SE Fosdick et al. “Bipolar Electrochemistry” Angew. Chem. Int. Ed. 2013, 52, 10438)

[0089] At this time, anion A - The movement of is replaced by electron movement within the metal piece, and the cation M n+ The movement of is replaced by the precipitation and dissolution of M.

[0090] The reversible balance between the dissolution and precipitation of metals is easily disrupted even by small polarizations, such as the potential difference caused by solution resistance when current flows through an external circuit.

[0091] In this case, no net electron transfer or electrochemical reaction occurs in the isolated metal M, and since the metal is electrically isolated, if metal precipitates at one end, dissolution occurs at the other end to precisely cancel it out.

[0092] Ion movement is replaced by electron movement, and since the speed of electron movement within a solid is much faster than the speed of ion movement in a solution, the internal resistance becomes smaller when such a metal piece (or multiple pieces) is present between the anode and cathode than when it is not.

[0093] Furthermore, since the precipitated metal exists in a low-density dendritic form, such as zinc or lithium (Li), it extends along the direction of ion movement under continuous current flow, thereby continuously reducing internal resistance. Similarly, when such metal is connected to an electrode, the internal resistance decreases.

[0094] In this case, an internal short circuit ultimately occurs within the cell, leading to thermal runaway.

[0095] The present invention relates to a system and method for detecting such a reduction in internal cell resistance, diagnosing in advance that a potential failure will occur due to the presence of abnormal metal within a battery cell or pack, and implementing a warning signal through a management circuit.

[0096]

[0097] To summarize the present invention, the internal resistance of a cell or battery is continuously monitored while the cell or battery is connected to a management circuit. This can be done at all times while the cell is operating, and in cases where the cell or battery does not have a management circuit, it is also done when connected to a charging circuit.

[0098] Subsequently, the internal resistance is derived from the cell voltage measured using a preset current pulse (charge or discharge pulse), and the internal resistance value obtained in the same charge state during each cycle is compared with the initial value, previous recorded value, or reference value; if the value decreases significantly, the management circuit or charger determines that there is a problem with the cell.

[0099] Subsequently, the management circuit stops charging and discharging and completely halts the operation of the cells until the problematic cell or battery is replaced.

[0100] In this case, the management circuit can operate the circuit breaker to stop further operation of the cell or battery pack. The faulty cell or multiple cells within the battery pack can be replaced, and the management circuit can be initialized.

[0101] The aforementioned process can be carried out via a computer (microcontroller), and each step can be performed in a measurement unit, a storage unit, a detection unit, a signal unit, and a circuit blocking unit.

[0102] The secondary battery management is carried out through the aforementioned steps, and the aforementioned system and method will be explained in detail below.

[0103]

[0104] A secondary battery management system according to one embodiment of the present invention may include: a measuring unit that measures the internal resistance of a battery in a predetermined charging state for every charge / discharge cycle; a storage unit that stores the internal resistance value of the battery measured by the measuring unit; a detection unit that calculates an internal resistance drop value D according to the following Equation 1 based on the internal resistance value stored in the storage unit, accumulates and counts the number of times the calculated internal resistance drop value D exceeds a reference value d, and determines whether the counted number exceeds a preset number m to detect the risk of an internal short circuit of the battery; a signal unit that indicates a warning signal when the detection unit determines the battery to be in a risk of an internal short circuit; and a circuit blocking unit that blocks the circuit of the battery to cut off the load on the battery when the detection unit determines the battery to be in a risk of an internal short circuit.

[0105] [Equation 1]

[0106]

[0107] Here, d and m are each greater than or equal to 0 real numbers, n is the number of charge or discharge cycles, and R i (n) is the nth measured internal resistance value, and R i (n-1) represents the n-1th measured internal resistance value.

[0108] At this time, since various uncertainties act on the measurement of internal resistance, the above reference value d cannot be chosen as an excessively small value.

[0109] For example, current pulse quality (e.g., rise time), voltage measurement timing (data recording speed), and external environmental conditions (e.g., temperature) can act as factors causing errors in the measured value.

[0110] Therefore, it is appropriate to set a minimum error of 5% (d value 0.05) as a reasonable standard value.

[0111] On the other hand, if the internal resistance drop value D is too high at the level of 0.4, it is a warning signal that it is approaching an irreversible level, and there is a very high probability that an internal short circuit will occur during use or the next charging process. In this case, battery usage must be stopped immediately.

[0112] Accordingly, the above reference value d can preferably be 0.05 to 0.4.

[0113] In addition, the above-mentioned number of times m is compared with the number of times the reference value d is exceeded to determine the risk of an internal short circuit.

[0114] At this time, the previously set number of times m can be 3 to 20.

[0115] At this time, if the previously set number of times m is less than 3, there is a possibility that it is not a serious problem situation, so m is set to 3 or more.

[0116] The specific value of m is determined according to the reference value d of the internal resistance drop value.

[0117] For example, when the reference value d is small from 0.05 to 0.1, m can be set to 5 to 20, and when the reference value d is 0.1 to 0.4, m can be set to 3 to 5.

[0118] However, the values ​​of d and m are not fixed and may vary depending on the size of the cell, module, or pack, so they are not limited to the aforementioned range.

[0119] Meanwhile, the measurement unit of the secondary battery management system may include a temperature measurement unit that corrects the internal resistance measured according to the operating temperature.

[0120] Generally, small secondary battery systems, in particular, are not equipped with active temperature controllers. Since internal resistance (or electrolyte resistance) is widely known to be highly sensitive to temperature changes, the variation in internal resistance according to operating temperature must be taken into account. Operating temperature is influenced by ambient temperature, which fluctuates depending on the season, location, and even the time of day.

[0121]

[0122] Figure 2 is a graph showing the correlation between iR-drop and temperature change near room temperature as a lithium-ion battery coin cell undergoes repeated charging and discharging.

[0123] Referring to Figure 2, the iR-drop clearly tends to decrease as the temperature increases. This means that unless the cell or battery pack is operated at a constant temperature, the measured iR-drop value must be corrected according to changes in operating temperature.

[0124] Meanwhile, an example of internal resistance correction due to temperature change is as follows.

[0125] The electrical conductivity of an electrolyte can generally be expressed in the following Arrhenius form.

[0126] σ = σ o exp(-E a / k B T)

[0127] Taking the reciprocal of this equation, the electrical resistivity becomes as follows.

[0128] ρ = ρ o exp(E a / k B T)

[0129] or,

[0130] [Equation 2]

[0131] Ri (n) = R i o (n)exp(E a / k B T)

[0132] Here, R i (n) is the internal resistance value measured in the nth cycle, R i o (n) is the internal resistance corrected for temperature in the nth cycle, E a is the activation energy, k B is the Boltzmann constant, and T is the temperature.

[0133] The measured internal resistance value is R = (geometric constant) . It can be corrected using the relationship. However, since batteries are generally operated in a relatively narrow temperature range of -20 to 80 °C (253 to 353 K), the exponential term can be linearized by taking only the first-order term of the Maclaurin series. Accordingly, the resistivity is approximately expressed as follows.

[0134] ρ = ρ o (1-aT) or ρ = ρ o (1-273a - aC)

[0135] Here, a is the temperature coefficient (a positive value), and C represents the temperature in degrees Celsius. Internal resistance is proportional to ρ, and the proportionality constant is a geometric factor of the electrolyte container or battery structure.] Therefore, internal resistance can be rewritten as follows in a more convenient form using degrees Celsius.

[0136] [Equation 3]

[0137] R i (n) = R i o (n)(1-bC)

[0138] Here, R i is the internal resistance measured from the iR-drop, and R i oε₀ represents the intrinsic internal resistance, b represents the temperature coefficient, and C represents the temperature measured during operation. For a cell or battery pack, the value of b can be determined in advance during the pack design phase or calculated based on measurement data during use.

[0139] Figure 3 is a graph showing the relationship between the iR value and the Celsius temperature C (iR vs. C) of a 2032 type coin cell.

[0140] Referring to Fig. 3, the thick solid line represents the typical slope b value, which was confirmed to be approximately 0.00116. Therefore, the temperature correction formula for internal resistance can be expressed as follows.

[0141] R i o (n) = R i (n) / (1-0.00116C)

[0142] Here, R i is the internal resistance measured as the iR-drop at a specific temperature C (°C), and R i o is the corrected intrinsic internal resistance. R in the same charge state at each cycle i After measuring, use the above formula to R i o Calculate the value and use this value for cycle-to-cycle comparison.

[0143] Meanwhile, the internal resistance corrected by the temperature measuring unit above can be corrected according to the following Equation 2.

[0144] [Equation 3]

[0145] R i (n) = R i o (n)(1-bC)

[0146] In Equation 3 above, Ri(n) is the internal resistance value measured in the nth cycle, Ri o(n) is the internal resistance corrected for temperature in the nth cycle, b is the temperature coefficient, and C is the temperature in degrees Celsius.

[0147] Meanwhile, as an example, the measuring unit can measure the internal resistance of a battery in various charge states (complete discharge, complete charge, or multiple charge points within the same cycle, etc.) using a device that measures internal resistance using current pulses. Furthermore, when calculating the internal resistance drop D from this, the internal resistance values ​​obtained in the same charge state for each cycle are used.

[0148] For example, the above internal resistance value measurement may use the AC impedance method, the current step method, or a method applying electrochemical principles.

[0149] In addition, as an example, the above storage unit can store continuously measured values ​​as non-volatile memory.

[0150] In addition, as an example, the detection unit may use a computer (microcontroller) that stores a program in which the conditions of Equation 1, reference value d, and number of times m are stored, and the internal resistance drop value is calculated based on the values ​​measured in the storage unit, and the number of times the reference value d is exceeded is accumulated and counted to determine whether the counted number exceeds a set m.

[0151] In addition, as an example, the signal unit may use a monitor that displays an internal short-circuit risk signal so that the user can recognize the internal short-circuit risk state when the detection unit determines the internal short-circuit risk state.

[0152] In addition, as an example, the circuit blocking unit may use a program that systematically cuts off the electricity of the connected battery circuit when the detection unit determines an internal short-circuit risk state, or a device that physically cuts off the circuit.

[0153] Below, we intend to explain a secondary battery management method utilizing the aforementioned secondary battery management system.

[0154]

[0155] A secondary battery cell management method according to one embodiment of the present invention is described.

[0156] The secondary battery cell management method according to the present invention can apply all the contents described for the aforementioned secondary battery management system, and although detailed explanations of overlapping parts have been omitted, they can be applied in the same way even if such explanations are omitted.

[0157]

[0158] A secondary battery management method using a secondary battery management system according to one embodiment of the present invention comprises: (a) an internal resistance value R when the battery is in the same charge state at the measurement unit. i (b) a step of measuring the internal resistance value R measured in step (a) and stored in the storage unit; i Based on the above, the detection unit calculates an internal resistance drop value according to the following formula 1; (c) the detection unit determines whether the internal resistance drop value D calculated in step (b) exceeds a preset reference value d, and if the calculated internal resistance drop value D is less than the reference value d, the process is repeated from step (a) in the next cycle, and if it exceeds the reference value d, the number of times the process is repeated is accumulated and counted; and (d) if the number of times the process is repeated is less than a preset number m, the secondary battery management system repeats from step (a) in the next cycle, and if the number of times the process is repeated exceeds the preset number m, the signal unit activates a short circuit warning signal for the battery cell or pack in question and the circuit breaker unit operates a circuit breaker to completely cut off the battery circuit; may be included.

[0159] [Equation 1]

[0160]

[0161] Here, d and m are each greater than or equal to 0 real numbers, n is the number of charge or discharge cycles, and Ri (n) is the nth measured internal resistance value, and R i (n-1) represents the n-1th measured internal resistance value.

[0162]

[0163] In the first step, (a) the internal resistance value R when the battery is in the same charge state at the measurement section. i Explains the steps for measuring.

[0164] In this case, the battery charge state refers to a predetermined battery charge state for each cycle, and the internal resistance drop value D is calculated by comparing the values ​​at the same charge state.

[0165] That is, in step (a) above, the same battery charge state includes a fully charged state, a minimum charged state, or a state in which a certain amount has been charged and discharged, and may include multiple charge states within the same cycle.

[0166] At this time, the battery being measured may be, for example, a secondary battery cell using zinc metal as the negative electrode or a secondary battery cell using lithium metal as the negative electrode using a non-aqueous electrolyte, but is not limited thereto.

[0167] As another example, a decrease in internal cell resistance can occur at any time if conductive solid particles with reversible electrochemical properties are present in the electrolyte solution (i.e., particles with fast forward and reverse reactions within the electrolyte solution and a sufficiently large exchange current).

[0168] For example, copper (Cu), zinc (Zn): in acidic and alkaline aqueous solutions; NiOOH: in alkaline solutions; nickel (Ni): in acidic solutions; lead (Pb): in acidic solutions; silver (Ag): in aqueous solutions containing silver salts; lithium (Li): in organic electrolytes containing lithium salts; lithium (Li): in lithium conductive solid electrolytes; sodium (Na): in organic electrolytes containing sodium salts; sodium (Na): in sodium conductive solid electrolytes; silicon (Si), iron (Fe), manganese (Mn), cobalt (Co), aluminum (Al), nickel (Ni): in organic electrolytes containing molten salts (so-called ionic liquids); and may include both electrodes containing alloy metals and conductive polymer electrodes.

[0169] In addition, the electrolyte solution may also contain gel electrolytes.

[0170] In the present invention, the same battery charge state may include, for example, a fully charged state or a fully discharged state, but is not limited thereto. The internal resistance value can be measured in any charge state during charging or discharging, and multiple charge and discharge points can be selected. From this, calculations for comparing internal resistance values ​​are performed using the internal resistance values ​​obtained at the same charge and discharge point in every cycle.

[0171] Specifically, the cell internal resistance is monitored at the same open-circuit voltage (no load) for all cycles, and can be monitored at the full charge voltage or a preset lowest voltage (e.g., cutoff voltage).

[0172] In this invention, since the cell internal resistance is a diagnostic parameter for detecting potential internal short circuits, the internal resistance must be measured accurately.

[0173] To this end, the internal resistance value can be measured in various ways, and the method of measuring the internal resistance value is not particularly limited.

[0174] For example, the above internal resistance measurement may include one or more methods from the group consisting of the AC impedance method, the current step method, or methods applying electrochemical principles, and preferably, the current step method may be used.

[0175] Figure 4 is an example of measuring resistance, showing the instantaneous voltage profile of a cell obtained under a current load, and is the instantaneous voltage profile of a cell or battery for an instantaneous current pulse.

[0176] Referring to Fig. 4, the vertical voltage drop or rise occurring upon the application of a current pulse has ohmic characteristics that appear immediately without time delay. This voltage change can be considered as a measure of the cell's internal resistance, which is primarily determined by the ion conduction resistance between the electrolyte and the separator matrix.

[0177] Generally, because the electrolyte concentration within the battery cell is high, the transport impedance does not have a significant effect for a short period of time (e.g., 1 ms to 1 s), and since the chemical structure inside the cell is constant, the change profile of the kinetic resistance does not change significantly over the cell lifespan. Meanwhile, since voltage measurements must be performed quickly enough not to be affected by double layer capacitance, it is desirable to measure the voltage change within 1 to 10 ms at the start or end point of the current load.

[0178] Therefore, internal resistance and its change can be evaluated by applying a simple current, and the internal resistance can be evaluated by applying an evaluation current of the same magnitude during each evaluation and utilizing the degree of voltage drop.

[0179] As shown in FIG. 4, the evaluation current (i) during a certain time (t) t ) Under load, the battery cell is at the voltage (V) of the corresponding charge state. oc Immediately V due to voltage drop in ) i It changes into.

[0180] In this case, the internal resistance can be obtained by dividing the voltage drop by the evaluation current, as shown in Equation 5 below.

[0181] [Equation 5]

[0182]

[0183] In this case, since a constant current is used, the cell voltage drop can serve as an indicator to directly measure the internal resistance.

[0184] The internal resistance or cell voltage can be measured at the same charge state of each charge / discharge cycle and compared with the value of the previous cycle.

[0185] Since internal resistance changes depending on the state of charge during the charging or discharging process, the diagnosis of cell short-circuit risk due to the presence of metal particles must be based on comparing internal resistance at the same state of charge in each cycle. Furthermore, the state of charge used for this internal resistance comparison may correspond to multiple states of charge within a single cycle.

[0186] Figure 5 is a flowchart of the subroutine for charging.

[0187] Figure 6 is V i This is a flowchart of the subroutine for measurement.

[0188] Referring to Figures 5 and 6, an example of a voltage measurement step for calculating the internal resistance drop value and the charging process of a battery cell or pack can be seen through the flowchart.

[0189] At this time, when charging is complete in Fig. 5, CS (Charging State) = 1, and V cutoff, h : Indicates the charging termination voltage.

[0190] Additionally, in Fig. 6, dt is pre-set according to battery size and specifications. This can be a wide range from several milliseconds to seconds, and the iR-drop (ΔV = V) in the energy storage cell / battery. oc -V iAfter that, the voltage profile can show a nearly flat shape with a slight curvature. The instantaneous voltage rise during a current drop can also be used.

[0191] Meanwhile, the internal resistance of the battery can be measured in the measurement unit, and the measured internal resistance values ​​can be stored in the storage unit.

[0192] Meanwhile, between the above steps (a) and (b), (a-1) internal resistance value R i By measuring the operating temperature, Ri according to Equation 2 or Equation 3 below o (n) further includes a step of correcting; and the corrected internal resistance value is Ri. o (n) is the internal resistance value R in step (b) above. i It can be applied as.

[0193] [Equation 2]

[0194] R i (n) = R i o (n)exp(E a / k B T)

[0195] In the above Equation 2, R i (n) is the internal resistance value measured in the nth cycle, R i o (n) is the internal resistance corrected for temperature in the nth cycle, E a is the activation energy, k B ε is the Boltzmann constant, T is the temperature, and

[0196] [Equation 3]

[0197] R i (n) = R i o (n)(1-bC)

[0198] In the above Equation 3, R i (n) is the internal resistance value measured in the nth cycle, R i o(n) is the internal resistance corrected for temperature in the nth cycle, b is the temperature coefficient, and C is the temperature in degrees Celsius.

[0199] Figure 7 is a flowchart of the internal resistance correction subroutine according to temperature.

[0200] Referring to FIG. 7, the corrected R is used in a subroutine to calculate the internal resistance after temperature correction. o (n) The value can be used to calculate the D value in a given charge state for comparison between cycles.

[0201] In other words, the corrected R o (n) value is R in step (b) i It is used as the value of (n).

[0202]

[0203] In the second step, the internal resistance value R measured in the above (a) and stored in the storage unit is i Based on this, the step of calculating the internal resistance drop value in the detection unit according to the following Equation 1 is described.

[0204] [Equation 1]

[0205]

[0206] D and m are each greater than or equal to 0, n is the number of charge or discharge cycles, and R i (n) is the internal resistance value measured in the nth cycle, and R i (n-1) represents the internal resistance value measured in the n-1th cycle.

[0207] For example, when first measured, R i (1) exists, but since there is no internal resistance value measured before the first one, the internal resistance drop value cannot be measured.

[0208] For the second measurement, the internal resistance drop value (R i (1)-R i (2)) / R i It can be measured by the calculation of (1).

[0209] At this time, the internal resistance value for the internal resistance drop value can be measured using the methods described above.

[0210] Meanwhile, internal resistance monitoring can be performed on a per-cell basis within the entire battery pack, on a per-module basis within a modular system, or on a per-pack basis in the case of small-scale packs.

[0211] In this case, for battery modules and packs, it is desirable to monitor internal resistance for cells connected in parallel.

[0212] Meanwhile, the internal resistance drop value of the battery can be calculated by the detection unit based on the internal resistance stored in the storage unit.

[0213]

[0214] In the third step, (c) the detection unit determines whether the internal resistance drop value D calculated in step (b) exceeds a preset reference value d, and if the calculated internal resistance drop value D is less than the reference value d, the process is repeated from step (a) in the next cycle, and if it exceeds the reference value d, the number of times it exceeds is accumulated and counted.

[0215] At this time, since various uncertainties act on the measurement of internal resistance, the above reference value d cannot be set too small.

[0216] For example, current pulse quality (e.g., rise time) and voltage measurement timing (data recording speed) can act as factors causing errors in the measured value.

[0217] Therefore, it is appropriate to set a minimum error of 5% (d value 0.05) as a reasonable standard value.

[0218] On the other hand, if the D value is too high, such as at the 0.4 level, it is a warning signal that it is approaching an irreversible level, and there is a very high probability that an internal short circuit will occur during use or the next charging process. Therefore, if the D value is too high, it is advisable to immediately stop using the battery.

[0219] Accordingly, the above reference value d can preferably be 0.05 to 0.4.

[0220] Additionally, in battery modules and packs, the D value becomes smaller as the number of cells connected in parallel increases, so the reference value d can be determined according to the battery arrangement or design.

[0221] Figure 8 shows an example of a unit for managing a cell or battery pack.

[0222] Referring to Fig. 8, it can be briefly seen that there is a part that applies a load (all load), a cell, module, or battery (cell, battery or module), a part that calculates and determines the internal resistance drop value D and operates the circuit breaker (manager), and a part that breaks the circuit (bistable circuit breaker).

[0223] At this time, if the internal resistance continuously decreases below a threshold value, the manager completely cuts off the load, and the box indicated by the dotted line represents a single manager unit, which can be extended to multiple units and applied repeatedly.

[0224] Meanwhile, actual power storage systems (power packs) can have a structure in which multiple units are connected in series or parallel.

[0225] As the number of units connected in series increases, the uncertainty of internal resistance monitoring tends to increase, and ideally, it is desirable to monitor all units individually.

[0226] However, from a practical perspective, if several units are monitored by a single manager, the response can be handled by adjusting the d value.

[0227] That is, if the battery includes cells or units connected in parallel, in step (c), the reference value d is a reference value d corrected by the following Equation 4. p It could be.

[0228] [Equation 4]

[0229]

[0230] In the above Equation 4, k is the number of parallel-connected cells or units, and d p is the corrected reference value.

[0231] To explain the process described above in detail, in the case of parallel-connected units, the value of d can be adjusted as shown in the following example.

[0232] Identical internal resistance R i When k units having are connected in parallel, the total internal resistance R T It is equal to Equation 6 below.

[0233] [Equation 6]

[0234] R T = R i / k

[0235] At this time, R T is the total internal resistance, and R i is the internal resistance of one unit, and k is the number of units.

[0236] In this case, if one of the k units exhibits a malfunction in which its internal resistance decreases by a critical reduction rate d, then the total internal resistance R of the parallel system T,p It is expressed as in Equation 7 below.

[0237] [Equation 7]

[0238] R T,p = R i / [k + d / (1-d)]

[0239] At this time, R T,p is the total internal resistance of the parallel system, and R i is the internal resistance of one unit, k is the number of units, and d is the critical internal resistance reduction rate defined for each unit.

[0240] Therefore, the critical internal resistance reduction rate d applied to the entire parallel-connected system p It is derived as shown in Equation 8 below.

[0241] [Equation 8]

[0242] d p = d / [k(1-d) +d]

[0243] At this time, d p is the critical internal resistance reduction rate, d is the critical internal resistance reduction rate defined for individual units, and k is the number of units.

[0244] In a parallel-connected system, this d p The risk of an internal short circuit can be evaluated by comparing the internal resistance drop values ​​calculated in each cycle based on the value.

[0245] Meanwhile, the counting step can be performed by accumulating in the detection unit.

[0246]

[0247] As a final step, (d) if the number of excess counts in step (c) is less than a preset number of times m, the secondary battery management system performs the process again from step (a) in the next cycle, and if the number of excess counts exceeds the preset number of times m, the signaling unit activates a battery cell or pack short-circuit warning signal and the circuit breaker in the circuit breaker unit operates to cut off the battery circuit.

[0248] At this time, the number of times m set above is compared with the number of times exceeding the reference value d to determine whether there is an internal short circuit.

[0249] At this time, the previously set number of times m can be 3 to 20.

[0250] At this time, if the previously set number of times m is less than 3, there is a possibility that it is not a serious problem situation, so m is set to 3 or more.

[0251] The specific value of m is determined according to the reference value d of the internal resistance drop value.

[0252] For example, when the reference value d is small from 0.05 to 0.1, m can be set to 5 to 20, and when the reference value d is 0.1 to 0.4, m can be set to 3 to 5.

[0253] However, the values ​​of d and m are not fixed and may vary depending on the size of the cell, module, or pack, so they are not limited to the aforementioned range.

[0254] Meanwhile, if a decrease in internal resistance is detected in a continuous cycle, for example, by comparing the voltages of the (n-1)th, nth, and (n+1)th cycles, a bistable relay is used to deactivate and disconnect the cell from the circuit, or a circuit breaker is actuated to prevent potential failure in subsequent cycles.

[0255] In this case, the short-circuit warning signal can be activated via a connected monitor or through sound, and the method of the warning signal is not limited.

[0256] Meanwhile, when the above circuit breaker operates, the load applied to the battery cell or pack is cut off, and in the case of a modular design, only the operation of the problematic module is stopped, while the remaining modules remain usable. This allows problems such as thermal runaway to be prevented in advance.

[0257] Accordingly, in step (d) above, if the battery circuit is cut off by operating the circuit breaker, after step (d) above, the method may further include the step of a user or maintenance technician replacing the battery cell or pack, initializing the circuit breaker and the measured values, and the secondary battery management system performing the steps again from step (a).

[0258] FIG. 9 is a subroutine flowchart for blocking a cell, module, or entire system, specifically a subroutine flowchart for disconnecting a cell or battery using a bistable circuit breaker when the internal resistance continuously decreases beyond a threshold value.

[0259] Referring to Fig. 9, a flowchart showing the circuit breaker operating with the activation of the warning signal can be seen.

[0260] Meanwhile, the activation of the short-circuit warning signal for the battery cell or pack can be performed in the signaling section, and the battery circuit interruption can be performed in the circuit interruption section.

[0261] Here, a bistable circuit breaker can completely cut off the load at the electrodes of a cell or battery and can be reset when the problematic cell or battery is replaced.

[0262]

[0263] Through the aforementioned steps, the secondary battery management method of the present invention can detect a battery cell having an internal short circuit risk.

[0264] FIG. 10 is a flowchart showing the entire process of a secondary battery management method according to one embodiment of the present invention.

[0265] Referring to Fig. 10, an example of a secondary battery management method can be seen.

[0266] At this time, FIG. 10 shows a mechanism for detecting a potential internal short circuit and interrupting the circuit by detecting a continuous decrease in internal resistance over several cycles in the same charge state (in this chart, a fully charged state is set as an example) during cell / battery operation.

[0267] At this time, V oc : Represents the open-circuit voltage and t w : Waiting time, which can be set from a few seconds to tens of minutes, d: preset value, which can range from 0.05 to 0.4, and m: preset value, which can range from 3 to 20.

[0268] Also, V cutoff, l : Indicates the discharge termination voltage.

[0269] To explain Fig. 10 in detail, first, Fig. 10 is an internal resistance monitoring and safety cutoff logic for a secondary battery power pack, which detects abnormal behavior of the battery by tracking the rate of change of internal resistance every cycle and protects the system by cutting off the circuit when necessary, and the specific steps are as follows.

[0270] First, the system measures the voltage drop (iR-drop) due to temperature and current load of the cell or battery at the preset state of charge (SOC) of each cycle, calculates the internal resistance of the corresponding cycle based on the measured voltage drop value, and ensures reliability by undergoing a temperature compensation process to eliminate errors caused by ambient temperature.

[0271] The internal resistance values ​​and key parameters calculated thereafter are stored in system memory in real time.

[0272] Next, the change in internal resistance is analyzed through comparison with the previous cycle, and the battery condition is diagnosed by specifically generating the internal resistance reduction rate (D).

[0273] At this time, as an immediate disconnection condition, if the internal resistance reduction rate (D) exceeds a preset safety threshold (e.g., 0.4) and shows a rapid decrease, the system determines that it is a fatal fault such as an internal short circuit and immediately disconnects the cell or battery through the circuit breaker.

[0274] As a potential risk detection condition, if the reduction rate (D) is greater than the reference value (d) but below the safety threshold, a count (j) is accumulated and recorded to check whether this reduction behavior is temporary.

[0275] On the other hand, if the internal resistance reduction rate (D) is smaller than the reference value (d), or if the internal resistance increases and D has a negative value, the system is considered to be operating within the normal range.

[0276] In particular, if the internal resistance shows increasing behavior again, all previous decrease counts (j) are reset to 0 to prevent unnecessary blocking errors and optimize system uptime.

[0277] If the abnormal internal resistance reduction phenomenon is repeated and the count (j) reaches the threshold number of consecutive reductions m, the system determines that there is a potential risk of ignition or explosion and activates the circuit breaker to physically disconnect the battery.

[0278] Subsequently, when the problematic cell or battery is replaced, the system restores all parameters to their initial state and resumes the normal monitoring routine.

[0279]

[0280] The present invention will be explained in more detail below through experimental examples. These experimental examples are solely for the purpose of illustrating the present invention, and the scope of the present invention is not limited by these experimental examples.

[0281]

[0282] Experimental Example: Measurement of Voltage Profile and Observation of Internal Short Circuit of H-Type Cell

[0283] Figure 11 shows the voltage profile of an H-type cell fabricated with two Zn electrodes and a 10 M ZnCl2 solution, representing the cell voltage profile during charging and discharging of the Zn metal electrode when there are Zn metal pieces in the ZnCl2 solution.

[0284] Figure 12 is a photograph of a Zn metal piece at points A, B, C, and D corresponding to the profile of Figure 3, showing (A) the initial state, (B) the end of the first discharge, (C) the end of the first charge, and (D) the time of internal short circuit occurrence of an H-type cell fabricated with two Zn electrodes and a 10 M ZnCl2 solution.

[0285] Referring to Figures 11 and 12, the newly formed metal has a dendritic shape and has a lower density compared to the original metal piece, and as this cycle continues, it can be seen that a short circuit inside the cell eventually occurs, as can be seen at point D of the profile in Figure 11 and D in Figure 12.

[0286] Through the experimental results above, failure caused by an internal short circuit, which is at least one fatal cell failure mechanism, can be clearly identified.

[0287] The voltage profile of Fig. 11 (cell voltage profile obtained through current pulses) shows the change in cell voltage at the open circuit voltage (voltage decrease in the case of discharge, voltage increase in the case of charging).

[0288] This voltage change includes all types of polarization, such as ohmic, kinetic, and concentration polarization. Generally, in secondary batteries, polarization increases as cycles are repeated due to the decomposition of electrode materials, phase changes, degradation of the mechanical integrity of the electrodes, and depletion of the electrolyte. In particular, the vertical voltage change (transient voltage change) in Fig. 11 corresponds to ohmic polarization, which is usually considered as internal resistance.

[0289] This internal resistance is the sum of the electrode resistance, electrode connection resistance, electrolyte resistance, and, in the case of a battery, the connection resistance of the cells.

[0290] Here, the electrolyte resistance accounts for most of the total internal resistance. In one embodiment of the present invention, when fine metal is deposited in the electrode separator or electrolyte of a cell or battery, or when metal is introduced due to external factors, the internal resistance may exhibit a characteristic of continuously decreasing as charge and discharge cycles are repeated according to the principle described above.

[0291] The metal fragments may be metal dendrites formed due to overcharging, may have fallen off during discharge, or may have been unintentionally introduced during the cell manufacturing process.

[0292] In addition, it can also be produced by reducing transition metal oxides to metals at the cathode when they are dissolved.

[0293] For example, even if such a metallic material exists within a separator structure in an energy storage cell and is electrically isolated from both electrodes, it undergoes a shape change by stretching along the direction of ion movement during repeated cycles, which leads to a decrease in solution resistance.

[0294] On the other hand, other polarization factors (kinetic, concentration) do not decrease as the cycle progresses but rather tend to increase.

[0295] Meanwhile, when charging and discharging are performed using the profile of Fig. 11, it can be observed that the voltage decreases before an internal short circuit occurs, which means that the internal short circuit of the battery can be detected through the drop in the internal resistance value measured by the voltage.

[0296]

[0297] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0298] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

1. A measuring unit that measures the internal resistance of the battery at a predetermined charge state during every charge / discharge cycle; A storage unit that stores the battery internal resistance value measured by the above-mentioned measuring unit; A detection unit that calculates an internal resistance drop value D according to the following Equation 1 based on the internal resistance value stored in the storage unit, accumulates and counts the number of times the calculated internal resistance drop value D exceeds a reference value d, and determines whether the counted number exceeds a preset number m to detect the risk of an internal short circuit of the battery; A signal unit that indicates a warning signal when the detection unit determines the battery to be in an internal short-circuit risk state; and A secondary battery management system characterized by including: a circuit breaker that cuts off the circuit of the battery to cut off the load on the battery when the detection unit determines that the battery is in an internal short-circuit risk state; [Equation 1] Here, d and m are each greater than or equal to 0 real numbers, n is the number of charge or discharge cycles, Ri(n) is the internal resistance value measured at the nth cycle, and R i (n-1) represents the internal resistance value measured in the n-1th cycle.

2. In Paragraph 1, A secondary battery management system characterized in that the measuring unit of the above secondary battery management system includes a temperature measuring unit that corrects the internal resistance measured according to the operating temperature.

3. In Paragraph 2, A secondary battery management system characterized in that the internal resistance corrected by the above temperature measuring unit is corrected according to the following Equation 2: [Equation 2] R i (n) = R i o (n)exp(E a / k B T) In the above Equation 2, R i (n) is the internal resistance value measured in the nth cycle, R i o (n) is the internal resistance corrected for temperature in the nth cycle, E a is the activation energy, k B is the Boltzmann constant, and T is the temperature.

4. In Paragraph 3, A secondary battery management system characterized in that the internal resistance corrected by the above temperature measuring unit is corrected according to the following Equation 3: [Equation 3] R i (n) = R i o (n)(1-bC) In the above Equation 3, R i (n) is the internal resistance value measured in the nth cycle, R i o (n) is the internal resistance corrected for temperature in the nth cycle, b is the temperature coefficient, and C is the temperature in degrees Celsius.

5. In Paragraph 1, A secondary battery management system characterized in that the above reference value d is 0.05 to 0.

4.

6. In Paragraph 1, A secondary battery management system characterized in that the above-mentioned preset number of times m is 3 to 20.

7. In Paragraph 1, If the above battery includes cells or units connected in parallel, In the above detection unit, the reference value d is a reference value d corrected by the following Equation 4. p Secondary battery management system characterized by: [Equation 4] In the above Equation 4, k is the number of parallel-connected cells or units, and dp is the corrected reference value.

8. In a secondary battery management method using the secondary battery management system of claim 1, (a) Internal resistance value R when the battery is in the same charge state at the measurement section i Step of measuring; (b) Internal resistance value R measured in step (a) above and stored in the storage unit i A step of calculating the internal resistance drop value in the detection unit according to the following Equation 1 based on the above; (c) a step of determining whether the internal resistance drop value D calculated in step (b) above exceeds a preset reference value d in the detection unit, and if the calculated internal resistance drop value D is less than the reference value d, performing the process again from step (a) above in the next cycle, and if it exceeds the reference value d, accumulating and counting the number of times it exceeds; and (d) a step in which, if the number of excess counts in step (c) is less than a preset number of times m, the secondary battery management system performs the process again from step (a) in the next cycle, and if the number of excess counts exceeds the preset number of times m, the signal unit activates a battery cell or pack short-circuit warning signal and the circuit breaker unit operates a circuit breaker to cut off the battery circuit; characterized by including: a secondary battery management method [Equation 1] Here, d and m are each greater than or equal to 0 real numbers, n is the number of charge or discharge cycles, Ri(n) is the n-th measured internal resistance value, and R i (n-1) represents the n-1th measured internal resistance value.

9. In Paragraph 8, Between the above steps (a) and (b), (a-1) Internal resistance R i By measuring the operating temperature, Ri according to Equation 2 or Equation 3 below o (n) further includes a step of correcting; and The above Ri, which is the corrected internal resistance value o (n) is the internal resistance value R in step (b) above. i A secondary battery management method characterized by being applied as: [Equation 2] R i (n) = R i o (n)exp(E a / k B T) In the above Equation 2, R i (n) is the internal resistance value measured in the nth cycle, R i o (n) is the internal resistance corrected for temperature in the nth cycle, E a is the activation energy, k B ε is the Boltzmann constant, T is the temperature, and [Equation 3] R i (n) = R i o (n)(1-bC) In Equation 3 above, Ri(n) is the internal resistance value measured in the nth cycle, Ri o (n) is the internal resistance corrected for temperature in the nth cycle, b is the temperature coefficient, and C is the temperature in degrees Celsius.

10. In Paragraph 8, If the above battery includes cells or units connected in parallel, In step (c) above, The above reference value d is the reference value d corrected by the following Equation 4. p A secondary battery management method characterized by: [Equation 4] In the above Equation 4, k is the number of parallel-connected cells or units, and d p is the corrected reference value.

11. In Paragraph 8, A secondary battery management method characterized in that the above reference value d is 0.05 to 0.

4.

12. In Paragraph 8, A secondary battery management method characterized in that the above-mentioned number of times m is 3 to 20.

13. In Paragraph 8, A secondary battery management method characterized by the fact that the above internal resistance value measurement includes one or more methods from the group consisting of the AC impedance method, the current step method, and a method applying electrochemical principles.

14. In Paragraph 8, In step (d) above, When the battery circuit is cut off by operating the above circuit breaker, After step (d) above, A secondary battery management method characterized by further including the step of a user or maintenance technician replacing a battery cell or pack, initializing the circuit breaker and measured values, and the secondary battery management system performing the steps again from (a).

15. In Paragraph 8, In step (a) above, the same battery charge state includes a fully charged state, a minimum charged state, or a state in which a certain amount has been charged and discharged, and A secondary battery management method characterized by being able to include multiple charge states within the same cycle.

16. In Paragraph 8, A secondary battery management method characterized by the fact that when the above-mentioned circuit breaker operates, the load applied to the battery cell or pack is cut off.

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