Overvoltage characteristic evaluation device and overvoltage characteristic evaluation method for battery

Abstract

An overvoltage characteristic evaluation device for a battery according to the present invention includes: a sensing unit that measures the current and voltage of a battery; and a control unit that determines a measured capacity history and a measured voltage history of a battery during a discharge event performed after polarization-induced pretreatment of the battery. The control unit determines a first measured voltage curve that indicates a correspondence between the measured capacity history and the measured voltage history. The control unit determines a second measured voltage curve that indicates a correspondence between the measured voltage history and a discharge depth history obtained by normalizing the measured capacity history relative to the total discharge capacity of the measured capacity history. The control unit determines a differential voltage curve by differentiating the measured voltage history relative to the charge depth history. The control unit determines overvoltage characteristic information associated with the polarization-induced pretreatment by comparing the differential voltage curve with a reference differential voltage curve.

Description

Technical Field

[0001] The present disclosure relates to a technology for evaluating overvoltage characteristics caused by polarization of a battery.

[0002] This application claims the benefit of Korean Patent Application No. 10-2020-0096200, filed on Jul. 31, 2020, the disclosure of which is incorporated herein by reference in its entirety. Background Art

[0003] Recently, the demand for portable electronic products such as laptop computers, cameras, and mobile phones has rapidly increased, and with the widespread development of electric vehicles, secondary batteries for energy storage, robots, and satellites, much research is being conducted on high-performance batteries that can be recharged repeatedly.

[0004] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium batteries, etc., and among them, lithium batteries have little or no memory effect, so they have received more attention than nickel-based batteries because they have the advantages of being able to be recharged whenever convenient, having a very low self-discharge rate and high energy density.

[0005] When predicting the performance of a battery, such as state of health (SOH) and state of charge (SOC), voltage and current are essentially required battery parameters. The capacity (or its change) of a battery can be determined based on the current measured using coulomb counting.

[0006] Differential voltage analysis (DVA) determines a differential voltage curve by differentiating a measured voltage curve that indicates the correlation between battery capacity and voltage. The curve then determines battery degradation parameters based on changes in the size and / or position of features in the differential voltage curve. Degradation parameters include, for example, capacity loss of the positive or negative electrode, lithium deposition, and so on.

[0007] When using DVA to determine degradation parameters, the overvoltage reflected on the measured voltage curve acts as noise in the differential voltage curve due to polarization (e.g., concentration gradient on the active material surface). Therefore, to suppress polarization that causes overvoltage, the process of obtaining the measured voltage curve is typically performed by intermittently discharging or charging the battery at a low current (e.g., less than 0.5C rate). As a result, overvoltage caused by polarization is a key parameter affecting battery degradation, but existing DVAs have difficulty in obtaining the overvoltage characteristics of batteries.

[0008] In addition, in order to develop batteries with high safety and performance, it is important to identify the correlation between polarization depending on the usage conditions of the battery and the overvoltage characteristics it causes. Summary of the Invention

[0009] Technical issues

[0010] The present disclosure is designed to solve the above-mentioned problems, and thus the present disclosure is directed to providing an apparatus and method for evaluating overvoltage characteristics of a battery using differential voltage analysis (DVA).

[0011] These and other purposes and advantages of the present disclosure can be understood through the following description and will be apparent from the embodiments of the present disclosure.In addition, it will be readily understood that the purposes and advantages of the present disclosure can be achieved through the means set forth in the appended claims and their combinations.

[0012] Technical Solution

[0013] According to one aspect of the present disclosure, a device for evaluating overvoltage characteristics of a battery includes: a sensing unit configured to measure current and voltage of a battery; and a control unit configured to use sensing information obtained from the sensing unit during a discharge event performed after polarization-inducing preconditioning of the battery to determine a measured capacity history and a measured voltage history indicating time-series changes in capacity and voltage of the battery. The control unit is configured to determine a first measured voltage curve indicating a correlation between the measured capacity history and the measured voltage history. The control unit is configured to determine a second measured voltage curve indicating a correlation between a depth of discharge history obtained by normalizing the measured capacity history relative to a total discharge capacity of the measured capacity history and the measured voltage history. The control unit is configured to determine a differential voltage curve from the second measured voltage curve by differentiating the measured voltage history relative to the depth of discharge history. The control unit is configured to determine overvoltage characteristic information associated with the polarization-inducing preconditioning by comparing the differential voltage curve with a reference differential voltage curve.

[0014] The discharge event may include a constant current discharge from a first time point to a second time point, wherein the first time point is when the voltage of the battery is equal to a first threshold voltage, and the second time point is when the voltage of the battery is equal to a second threshold voltage lower than the first threshold voltage.

[0015] The control unit is configured to determine a concentrated overvoltage range, the concentrated overvoltage range being a range in which a differential voltage difference between a differential voltage curve and a reference differential voltage curve is equal to or greater than a threshold difference throughout a range of a depth of discharge history. The overvoltage characteristic information includes the concentrated overvoltage range.

[0016] The control unit may be configured to determine an area of ​​a concentrated overvoltage region defined by the concentrated overvoltage range, the differential voltage curve, and the reference differential voltage curve. The overvoltage characteristic information further includes the area of ​​the concentrated overvoltage region.

[0017] The area indicates the magnitude of overvoltage accumulated in the battery within the concentrated overvoltage range.

[0018] The control unit may be configured to determine the threshold difference by dividing an integrated value of the differential voltage difference within a reference range from a predetermined first discharge depth to a predetermined second discharge depth over the entire range of the discharge depth history by a size of the reference range.

[0019] The control unit may be configured to determine a concentrated overvoltage range in the reference range.

[0020] According to another aspect of the present disclosure, a method for evaluating overvoltage characteristics of a battery includes: using sensing information of current and voltage of a battery obtained during a discharge event performed after polarization-inducing preconditioning of the battery to determine a measured capacity history and a measured voltage history indicating time-series changes in the capacity and voltage of the battery; determining a first measured voltage curve indicating a correlation between the measured capacity history and the measured voltage history; determining a second measured voltage curve indicating a correlation between a depth of discharge history obtained by normalizing the measured capacity history relative to a total discharge capacity of the measured capacity history and the measured voltage history; determining a differential voltage curve from the second measured voltage curve by differentiating the measured voltage history relative to the depth of discharge history; and determining overvoltage characteristic information associated with the polarization-inducing preconditioning by comparing the differential voltage curve with a reference differential voltage curve.

[0021] The step of determining overvoltage characteristic information associated with polarization induced preprocessing may include determining a concentrated overvoltage range, which is a range in which a differential voltage difference between a differential voltage curve and a reference differential voltage curve is equal to or greater than a threshold difference in the entire range of the discharge depth history.

[0022] The step of determining overvoltage characteristic information associated with the polarization-inducing pre-processing may further include determining an area of ​​a concentrated overvoltage region defined by the concentrated overvoltage range, the differential voltage curve, and the reference differential voltage curve.

[0023] Beneficial effects

[0024] According to at least one of the embodiments of the present disclosure, differential voltage analysis (DVA) can be used to evaluate the overvoltage characteristics of a battery. In particular, the correlation between the measured voltage history and the measured capacity history can be converted into a correlation between the measured voltage history and the depth of discharge history. Here, the depth of discharge history can be obtained by normalizing the measured capacity history of the measured voltage curve obtained during a discharge event performed after the polarization-induced pretreatment of the battery to a depth of discharge history (in the range of 0% to 100%). Therefore, as a result of the evaluation, a concentrated overvoltage range can be obtained in which the overvoltage characteristics of the battery that has been subjected to polarization-induced pretreatment are presented in a concentrated manner.

[0025] In addition, according to at least one of the embodiments of the present disclosure, the magnitude of the overvoltage accumulated within the concentrated overvoltage range may be additionally obtained as an evaluation result.

[0026] The effects of the present disclosure are not limited to the above-described effects, and those skilled in the art will clearly understand these and other effects from the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the detailed description of the present disclosure described below, serve to provide a further understanding of the technical aspects of the present disclosure, and thus the present disclosure should not be construed as being limited to the accompanying drawings.

[0028] Figure 1 is a diagram exemplarily showing a configuration of a battery evaluation system according to the present disclosure.

[0029] Figure 2 It is a graph used as a reference when describing the relationship between the magnitude of the overvoltage and the measured voltage curve.

[0030] Figure 3 This is the graph used as a reference when describing the results of normalizing the measured voltage curve.

[0031] Figure 4 A graph used as a reference when describing the differential voltage curve corresponding to the measured voltage curve.

[0032] Figure 5 This is a graph referred to when describing the operation of determining the overvoltage characteristics from the differential voltage curve.

[0033] Figure 6 is a flowchart exemplarily illustrating a method for evaluating overvoltage characteristics of a battery according to a first embodiment of the present disclosure.

[0034] Figure 7 is a flowchart exemplarily illustrating a method for evaluating overvoltage characteristics of a battery according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and the appended claims should not be interpreted as limited to the general meaning and dictionary meaning, but should be interpreted according to the meaning and concept corresponding to the technical aspects of the present disclosure based on the principle that the inventor is allowed to appropriately define the terms for the best interpretation.

[0036] Therefore, the embodiments described herein and the illustrations shown in the accompanying drawings are merely the most preferred embodiments of the present disclosure and are not intended to fully describe the technical aspects of the present disclosure, and it should be understood that various other equivalents and modifications may be made thereto when an application is filed.

[0037] Terms including ordinal numbers such as “first,” “second,” etc. are used to distinguish one element from another among various elements, but are not intended to limit the elements by the terms.

[0038] Unless the context clearly indicates otherwise, it should be understood that when used in this specification, the term "comprising" specifies the presence of the elements described, but does not exclude the presence or addition of one or more other elements. In addition, the term "control unit" as used herein refers to a processing unit of at least one function or operation, and this can be implemented by hardware and software alone or in combination.

[0039] Additionally, throughout this specification, it will be further understood that when an element is referred to as being “connected to” another element, it can be directly connected to the other element or intervening elements may be present.

[0040] Figure 1 is a diagram exemplarily showing a configuration of a battery evaluation system according to the present disclosure, Figure 2 It is a graph used to describe the relationship between the magnitude of overvoltage and the measured voltage curve. Figure 3 This is the graph used to describe the results of normalizing the measured voltage curve. Figure 4 is a graph to which reference is made when describing the differential voltage curve corresponding to the measured voltage curve, and Figure 5 This is a graph referred to when describing the operation of determining the overvoltage characteristics from the differential voltage curve.

[0041] refer to Figure 1 A battery evaluation system 1 is provided to evaluate the overvoltage characteristics of a battery B. The battery B may be a lithium-ion battery. The battery B is not limited to a specific type and may include any type of battery that can be repeatedly charged.

[0042] The battery evaluation system 1 includes an overvoltage characteristic evaluation apparatus 10 (hereinafter referred to as “evaluation apparatus”) and a charging / discharging device 20 .

[0043] The charging / discharging device 20 is electrically connected to the current path for charging / discharging battery B. That is, the charging / discharging device 20 is configured to be electrically connected in parallel to battery B via a pair of terminals. The charging / discharging device 20 may include a constant current circuit to adjust the current rate (referred to as the C-rate) of the current flowing through battery B. The charging / discharging device 20 is configured to adjust the current rate (referred to as the 'C-rate') of the current used to charge or discharge battery B in response to a command from the evaluation device 10. The charging / discharging device 20 may provide only one of the constant current discharge function and the constant current charge function.

[0044] The evaluation device 10 includes a sensing unit 110 and a control unit 120. The evaluation device 10 may further include at least one of an interface unit 130 and a temperature chamber 140. The following description is made assuming that the evaluation device 10 includes all of the sensing unit 110, the control unit 120, the interface unit 130, and the temperature chamber 140.

[0045] The sensing unit 110 includes a voltage sensor 111 and a current sensor 112 .

[0046] The voltage sensor 111 is provided to be electrically connectable in parallel to the battery B. The voltage sensor 111 is configured to measure a voltage across the battery B and generate a voltage signal indicating the measured voltage.

[0047] The current sensor 112 is provided so as to be electrically connected in series to the battery B through a current path connecting the battery B and the charging / discharging device 20. The current sensor 112 is configured to measure current flowing through the battery B and generate a current signal indicating the measured current.

[0048] The control unit 120 may collect sensing information including a voltage signal and a current signal synchronously obtained from the sensing unit 110 .

[0049] The control unit 120 may be implemented in hardware using at least one of an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a microprocessor, or an electrical unit for performing other functions. The control unit 120 may have a memory embedded therein. The memory may include at least one type of storage medium, such as a flash memory type, a hard disk type, a solid-state drive (SSD) type, a silicon disk drive (SDD) type, a multimedia card micro type, a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), or a programmable read-only memory (PROM). The memory may store data and programs required for the computational operations (described below) of the control unit 120. The control unit 120 may record data indicating the results of the computational operations in the memory.

[0050] The control unit 120 is operatively coupled to the charging / discharging device 20, the sensing unit 110, the interface unit 130, and the temperature chamber 140. Operatively coupled refers to direct / indirect connection to send and receive signals in one or two directions.

[0051] The interface unit 130 is configured to support wired or wireless communication between the control unit 120 and the user terminal 2 (e.g., a personal computer). The wired communication may be, for example, a controller area network (CAN) communication, and the wireless communication may be, for example, Zigbee or Bluetooth communication. The communication protocol is not limited to a specific type and may include any communication protocol that supports wired / wireless communication between the control unit 120 and the user terminal 2. The interface unit 130 may include an output device (e.g., a display, a speaker) for providing information received from the control unit 120 and / or the user terminal 2 in a recognizable format.

[0052] The control unit 120 may determine a measured capacity history and a measured voltage history based on the sensing information (i.e., a time series of measured current values ​​and a time series of measured voltage values) collected from the sensing unit 110 at preset time intervals during a discharge event of battery B. The measured capacity history indicates a time series change in the discharge capacity of battery B from the start to the end of the discharge event. The measured voltage history indicates a time series change in the voltage of battery B from the start to the end of the discharge event. During the discharge event, a larger discharge capacity in the measured capacity history corresponds to a lower voltage in the measured voltage history.

[0053] The control unit 120 may store the measured capacity history and the measured voltage history in a memory. The discharge event may include a constant current discharge. The discharge event may be performed when the temperature chamber 140 maintains the ambient temperature of the battery B at a preset temperature.

[0054] The voltage from battery B is equal to the first threshold voltage V TH1 At the first time point, the voltage of battery B is equal to or lower than the first threshold voltage V TH1 The second threshold voltage V TH2 For example, the first threshold voltage V TH1 is the open circuit voltage (OCV) of battery B when battery B is fully charged, and may be the same as a preset value (ie, the charge end voltage). The second threshold voltage V TH2 It may be equal to a preset value, which is the OCV when battery B is fully discharged (ie, the end-of-discharge voltage). The C-rate of the constant current discharge may be a high current such as a 6.5C-rate.

[0055] exist Figure 2 , the X-axis (vertical axis) represents voltage and the Y-axis (horizontal axis) represents discharge capacity. A first reference voltage curve 210 is pre-acquired by a discharge event of a reference battery (not shown) that has undergone reference preconditioning, and a first measured voltage curve 220 is acquired by a discharge event of battery B that has undergone polarization induction preconditioning. The first reference voltage curve 210 indicates the correlation between the reference capacity history and the reference voltage history. The reference capacity history indicates the time series change of the discharge capacity of the reference battery from the beginning to the end of the discharge event. The reference voltage history indicates the time series change of the voltage of the reference battery from the beginning to the end of the discharge event. Battery B and the reference battery are manufactured to have the same electrical and chemical characteristics.

[0056] Below are examples of each of the reference preconditioning and the polarization-inducing preconditioning.

[0057] <Reference Preprocessing> The reference preprocessing can include a series of the following processes.

[0058] - Fully discharge from a predetermined SOC (e.g., 30%) using a predetermined first current curve

[0059] - Place at a predetermined first temperature (e.g., 80°C) for a predetermined first time (e.g., 6 hours)

[0060] - Fully charge using a predetermined second current curve

[0061] <Polarization Inducing Pretreatment> Polarization inducing pretreatment may include a series of the following treatments.

[0062] - Fully discharge from a predetermined SOC (e.g., 30%) using a predetermined first current curve

[0063] - Place at a predetermined second temperature (e.g., 25°C) for a predetermined second time (e.g., 3 hours)

[0064] - Fully charge using a predetermined second current curve

[0065] When comparing the reference pretreatment with the polarization-inducing pretreatment in the above example, the polarization-inducing pretreatment differs from the reference pretreatment in that the polarization-inducing pretreatment places Battery B at a second temperature (room temperature) rather than a first temperature (high temperature). Due to this difference, the reference battery undergoes a discharge event in a state where polarization has completely disappeared, while Battery B undergoes a discharge event in a state where Battery B is still polarized. While the reference pretreatment is performed to reduce the polarization of Battery B to below a predetermined level at the start of the discharge event, the reference pretreatment is not limited to the above example. Similarly, when the polarization-inducing pretreatment is performed to form a greater polarization in Battery B than in the reference pretreatment, the polarization-inducing pretreatment is not limited to the above example.

[0066] After the user places battery B in the temperature chamber 140, the user can request the evaluation device 10 to perform polarization-inducing preconditioning. In response to the request received from the user terminal 2 through the interface unit 130, the control unit 120 can control the charging / discharging device 20 and the temperature chamber 140 to sequentially perform the polarization-inducing preconditioning process. The temperature chamber 140 is a device having an internal space in which battery B can be accommodated, and the temperature of the internal space (i.e., the ambient temperature of battery B) can be detected and adjusted. In response to the completion of the polarization-inducing preconditioning, the control unit 120 can perform a discharge event on battery B. Alternatively, a separate tester can be used instead of the evaluation device 10 to perform the polarization-inducing preconditioning.

[0067] from Figure 2 It can be seen that the difference between the first reference voltage curve 210 and the first measured voltage curve 220, corresponding to the polarization difference between battery B and the reference battery, occurs during the discharge event. Specifically, the first measured voltage curve 220 shows a voltage reduction behavior that is generally faster than the first reference voltage curve 210, and it can be seen that the difference between the first reference voltage curve 210 and the second threshold voltage V TH2 The corresponding total discharge capacity of battery B is Q B_total The total discharge capacity Q of the reference battery ref_total This is because the remaining polarization in cell B appears as an overvoltage due to the current of the discharge event.

[0068] As a result, the reference voltage history of the first reference voltage curve 210 and the measured voltage history of the first measured voltage curve 220 have the same voltage range, but the reference capacity history of the first reference voltage curve 210 and the measured capacity history of the first measured voltage curve 220 do not have the same capacity range. Therefore, in order to easily compare the first reference voltage curve 210 and the first measured voltage curve 220, the control unit 120 can determine the first depth of discharge history and the second depth of discharge history having the same range of 0-1 or 0-100% by normalizing the reference capacity history of the first reference voltage curve 210 and the measured capacity history of the first measured voltage curve 220, respectively.

[0069] The reference capacity history of the first reference voltage curve 210 and the first depth of discharge history may have the following relationship.

[0070]

[0071] When i is a natural number of 1 or greater, Q ref_total is the total discharge capacity of the first reference voltage curve 210, Q ref [i] is the discharge capacity of the reference battery determined at time i during the discharge event, and DoD ref [i] is achieved by using Q ref_total Q ref [i] The value obtained by normalization. The first discharge depth history can be a set of DoD during the discharge event ref [i](time series).

[0072] The measured capacity history of the first measured voltage curve 220 and the second depth of discharge history may have the following relationship.

[0073]

[0074] When j is a natural number of 1 or greater, Q B_total is the total discharge capacity of the first measured voltage curve 220, Q B [j] is the discharge capacity of battery B determined at time i during the discharge event, and DoD B [j] is achieved by using Q B_total Q B [j] is a value obtained by normalization. The second discharge depth history can be a set of DoD during the discharge event B [j](time series).

[0075] exist Figure 3 In the figure, the X-axis (vertical axis) indicates voltage, and the Y-axis (horizontal axis) indicates Figure 2 The discharge capacity corresponds to the discharge depth. Figure 3, the control unit 120 may determine the second reference voltage curve 310 from the first reference voltage curve 210 by converting the correlation between the reference capacity history and the reference voltage history into a correlation between the first depth of discharge history and the reference voltage history.

[0076] Likewise, the control unit 120 can determine the second measured voltage curve 320 from the first measured voltage curve 220 by converting the correlation between the measured capacity history and the measured voltage history of the first measured voltage curve 220 into a correlation between the second discharge depth history and the measured voltage history. As a result, the reference voltage history of the second reference voltage curve 310 and the measured voltage history of the second measured voltage curve 320 are scaled relative to the discharge depth within a common range of 0-100%.

[0077] exist Figure 4 In the figure, the X-axis (vertical axis) indicates the differential voltage, and the Y-axis (horizontal axis) indicates the differential voltage. Figure 3 The differential voltage dV / dQ is the ratio of the voltage change dV to the discharge capacity (or depth of discharge) change dQ.

[0078] refer to Figure 4 , the control unit 120 may determine the reference differentiated voltage curve 410 from the second reference voltage curve 310 by differentiating the reference voltage history of the second reference voltage curve 310 with respect to the first depth of discharge history.

[0079] Alternatively, the reference differential voltage curve 410 may be recorded in a memory based on the results of a previously performed test, rather than being determined by the control unit 120. That is, when a discharge event is performed in a zero-polarization state of the battery B (i.e., when the battery B has not undergone polarization-inducing preconditioning), the reference differential voltage curve 410 may be preset as the differential voltage curve.

[0080] The control unit 120 can determine a differential voltage curve 420 from the second measured voltage curve 320 by differentiating the measured voltage history of the second measured voltage curve 320 relative to the second discharge depth history. The differential voltage curve 420 can indicate a time series of ratios of voltage change to (i) discharge depth (or its corresponding discharge capacity) and (ii) a unit change in discharge depth (or a corresponding change in discharge capacity) over the entire range of 0 to 100%.

[0081] The control unit 120 determines overvoltage characteristic information of the battery B from the differential voltage curve 420 by comparing the reference differential voltage curve 410 with the differential voltage curve 420. The control unit 120 may associate the overvoltage characteristic information with the polarization inducing preconditioning and record it in a memory.

[0082] Figure 5is an exemplary illustration indicating the reference range ΔR ref A graph of a polarization comparison curve 500 showing the correlation between the internal differential voltage difference ΔdV / dQ and the depth of discharge. Figure 5 In FIG. 1 , the X-axis (vertical axis) indicates the differential voltage difference ΔdV / dQ, and the Y-axis (horizontal axis) indicates the differential voltage difference ΔdV / dQ. Figure 4 The same as the Y axis.

[0083] The control unit 120 may be configured to be relative to the reference range ΔR ref The differential voltage difference ΔdV / dQ between the reference differential voltage curve 410 and the differential voltage curve 420 is determined by the discharge depth within the range. The differential voltage difference ΔdV / dQ corresponding to each discharge depth may be a value obtained by subtracting the differential voltage of the reference differential voltage curve 410 from the differential voltage of the differential voltage curve 420. ref The reference range ΔR is from a predetermined first depth of discharge DoD1 greater than 0% (eg, 10%) to a predetermined second depth of discharge DoD2 less than 100% (eg, 90%). ref The reason is that the discharge reaction of battery B is very unstable in the range of 0% to the first depth of discharge DoD1 and in the range of the second depth of discharge DoD2 to 100%.

[0084] The control unit 120 may determine the concentrated overvoltage range ΔR op , that is, the range in which the differential voltage difference ΔdV / dQ of the polarization comparison curve 500 is equal to or greater than the threshold difference ΔD in the entire range of the discharge depth history (i.e., 0% to 100%). The overvoltage characteristic information may include a concentrated overvoltage range ΔR op For example, in Figure 5 In the first discharge depth DoD A To the second depth of discharge DoD B Concentrated overvoltage range ΔR op The differential voltage of the differential voltage curve 420 is kept higher than the differential voltage of the reference differential voltage curve 410 by at least the threshold difference ΔD. The threshold difference ΔD may be a preset value. Alternatively, the control unit 120 may select a differential voltage within a reference range ΔR based on the differential voltage difference ΔdV / dQ. ref For example, the control unit 120 may determine the threshold difference ΔD to be equal to the value obtained by dividing the integration value by the reference range ΔR. ref The value obtained by dividing the size of (i.e., DoD2-DoD1).

[0085] The control unit 120 may be further configured to determine the area of ​​the concentrated overvoltage region 430. The concentrated overvoltage region 430 is defined by the concentrated overvoltage range ΔR op, the differential voltage curve 420 and the reference differential voltage curve 410. The area of ​​the concentrated overvoltage region 430 is within the concentrated overvoltage range ΔR op The difference between the voltage change of the second measurement voltage curve 320 and the voltage change of the second reference voltage curve 310 on the graph. That is, the area of ​​the concentrated overvoltage region 430 indicates the area of ​​the concentrated overvoltage range ΔR. op The magnitude of the overvoltage accumulated in battery B is given in FIG. The overvoltage characteristic information may further include the area of ​​the concentrated overvoltage region.

[0086] Figure 6 is a flow chart exemplarily illustrating a method for evaluating the overvoltage characteristics of a battery according to the first embodiment of the present disclosure. After completing the polarization induction pretreatment of battery B, perform Figure 6 method.

[0087] Reference Figures 1 to 6 In step S610, the control unit 120 determines a measured capacity history and a measured voltage history indicating time series changes in the capacity and voltage of the battery B, respectively, during the discharge event of the battery B. The measured capacity history is based on the accumulated value of the current measured by the current sensor 112 at predetermined time intervals during the discharge event. The measured voltage history is based on the voltage across the battery B measured by the voltage sensor 111 at predetermined time intervals during the discharge event.

[0088] In step S620 , the control unit 120 determines a first measured voltage curve 220 indicating a correlation between the measured capacity history and the measured voltage history.

[0089] In step S630, the control unit 120 calculates the total discharge capacity Q of the measured capacity history by comparing the measured capacity history to the total discharge capacity Q of the measured capacity history. B_total Normalization is performed to determine a second measured voltage curve 320 indicating a correlation between the depth of discharge history corresponding to the measured capacity history and the measured voltage history.

[0090] In step S640 , the control unit 120 determines a differentiated voltage curve 420 from the second measured voltage curve 320 by differentiating the measured voltage history with respect to the depth of discharge history.

[0091] In step S650, the control unit 120 determines the reference range ΔR. ref The depth of discharge within the battery determines the differential voltage difference between the differential voltage curve and the reference differential voltage curve.

[0092] In step S660, the control unit 120 determines the concentrated overvoltage range ΔR op , that is, the differential voltage difference is equal to or greater than the reference range ΔR refThe threshold difference ΔD may be pre-recorded in a memory.

[0093] In step S670, the control unit 120 determines the concentrated overvoltage range ΔR op , the differential voltage curve 420 and the reference differential voltage curve 410 define the concentrated overvoltage region 430. Step S670 can be performed from Figure 6 Omitted from the method.

[0094] In step S680, the control unit 120 outputs an evaluation message indicating overvoltage characteristic information of the battery B. The overvoltage characteristic information includes a concentrated overvoltage range ΔR op or at least one of the area of ​​the concentrated overvoltage region 430. The interface unit 130 may transmit the evaluation message to the user terminal 2 or output visual and / or auditory information corresponding to the evaluation message.

[0095] Figure 7 is a flow chart exemplarily illustrating a method for evaluating the overvoltage characteristics of a battery according to the second embodiment of the present disclosure. After completing the polarization induction pretreatment of battery B, perform Figure 7 When describing the second embodiment, repeated descriptions similar to those of the first embodiment may be omitted herein.

[0096] Figures 1 to 5 and Figure 7 In step S710 , the control unit 120 determines a measured capacity history and a measured voltage history indicating time-series changes in the capacity and voltage of the battery B during a discharge event of the battery B.

[0097] In step S720 , the control unit 120 determines a first measured voltage curve 220 indicating a correlation between the measured capacity history and the measured voltage history.

[0098] In step S730, the control unit 120 calculates the total discharge capacity Q of the measured capacity history by comparing the measured capacity history to the total discharge capacity Q of the measured capacity history. B_total Normalization is performed to determine a second measured voltage curve 320 indicating a correlation between the depth of discharge history corresponding to the measured capacity history and the measured voltage history.

[0099] In step S740 , the control unit 120 determines a differentiated voltage curve 420 from the second measured voltage curve 320 by differentiating the measured voltage history with respect to the depth of discharge history.

[0100] In step S750, the control unit 120 calculates the value of the reference range ΔR. ref The depth of discharge within 400V determines the differential voltage difference between the differential voltage curve 420 and the reference differential voltage curve 410.

[0101] In step S752, the control unit 120 determines whether the differential voltage difference is within the reference range ΔR ref The integral value within is greater than the reference integral value. When the value of step S752 is "yes", step S756 is executed. The value of step S752 is "no" which may indicate that a calculation error occurred in steps S710 to S750. When the value of step S752 is "no", step S754 is executed.

[0102] In step S754, the control unit 120 outputs a fault message. The interface unit 130 may transmit the fault message to the user terminal 2 or output visual and / or auditory information corresponding to the fault message. Steps S752 and S754 may be Figure 7 is omitted from the method, and after step S750, step S756 can be executed.

[0103] In step S756, the control unit 120 determines the differential voltage difference within the reference range ΔR. ref The threshold difference ΔD is determined by the integrated value on .

[0104] In step S760, the control unit 120 determines the concentrated overvoltage range ΔR op , that is, the differential voltage difference is equal to or greater than the reference range ΔR ref within the range of the threshold difference ΔD.

[0105] In step S770, the control unit 120 determines the concentrated overvoltage range ΔR op , the differential voltage curve 420 and the reference differential voltage curve 410 define the area of ​​the concentrated overvoltage region 430. Step S770 can be obtained from Figure 7 Omitted from the method.

[0106] In step S780, the control unit 120 outputs an evaluation message indicating the overvoltage characteristic information of the battery B. The overvoltage characteristic information includes the threshold difference ΔD, the concentrated overvoltage range ΔR, and the threshold difference ΔD. op or at least one of the area of ​​the concentrated overvoltage region 430 .

[0107] The embodiments of the present disclosure described above may be implemented not only by devices and methods, but also by programs that execute functions corresponding to the configurations of the embodiments of the present disclosure or a recording medium having the programs recorded thereon, and those skilled in the art may easily implement such implementation schemes from the disclosure of the previously described embodiments.

[0108] While the present disclosure has been described above with respect to a limited number of embodiments and drawings, it is not limited thereto, and it will be apparent to those skilled in the art that various modifications and changes may be made thereto within the technical aspects of the present disclosure and the equivalent scope of the appended claims.

[0109] In addition, without departing from the technical aspects of the present disclosure, those skilled in the art may make many substitutions, modifications and changes to the present disclosure described above. The present disclosure is not limited to the above-mentioned embodiments and drawings, and some or all of the embodiments may be selectively combined to allow various modifications.

Claims

1. An overvoltage characteristic evaluation device for a battery, the overvoltage characteristic evaluation device comprising: a sensing unit configured to measure a current and a voltage of the battery; as well as a control unit configured to determine a measured capacity history and a measured voltage history indicating time series changes in capacity and voltage of the battery using sensing information obtained from the sensing unit during a discharge event performed after the polarization inducing pre-conditioning of the battery, Wherein, the control unit is configured as: determining a first measured voltage curve indicating a correlation between the measured capacity history and the measured voltage history, determining a second measured voltage curve indicating a correlation between a depth of discharge history obtained by normalizing the measured capacity history with respect to a total discharge capacity of the measured capacity history and the measured voltage history, determining a differentiated voltage curve from the second measured voltage curve by differentiating the measured voltage history with respect to the depth of discharge history, and Overvoltage characteristic information associated with the polarization inducing pre-processing is determined by comparing the differential voltage curve with a reference differential voltage curve.

2. The overvoltage characteristic evaluation device according to claim 1, wherein The measured capacity history is based on an accumulated value of current measured at predetermined time intervals during the discharge event, and the measured voltage history is based on a voltage across the battery measured at predetermined time intervals during the discharge event.

3. The overvoltage characteristic evaluation device according to claim 1, wherein: The discharge event includes a constant current discharge from a first time point to a second time point, The first time point is a time point when the voltage of the battery is equal to a first threshold voltage, and The second time point is a time point at which the voltage of the battery is equal to a second threshold voltage lower than the first threshold voltage.

4. The overvoltage characteristic evaluation device according to claim 1, wherein: The discharge event is performed while the ambient temperature of the battery is maintained at a preset temperature.

5. The overvoltage characteristic evaluation device according to claim 1, wherein The control unit is configured to determine a concentrated overvoltage range, the concentrated overvoltage range being a range in which a differential voltage difference between the differential voltage curve and the reference differential voltage curve is equal to or greater than a threshold difference in the entire range of the discharge depth history, and The overvoltage characteristic information includes the concentrated overvoltage range.

6. The overvoltage characteristic evaluation device according to claim 5, wherein: The control unit is configured to determine an area of ​​a concentrated overvoltage region, the concentrated overvoltage region being defined by the concentrated overvoltage range, the differential voltage curve, and the reference differential voltage curve, and The overvoltage characteristic information also includes the area of ​​the concentrated overvoltage region.

7. The overvoltage characteristic evaluation device according to claim 6, wherein: The area indicates the magnitude of overvoltage accumulated in the battery within the concentrated overvoltage range.

8. The overvoltage characteristic evaluation device according to claim 5, wherein: The control unit is configured to determine the threshold difference by dividing an integrated value of the differential voltage difference within a reference range from a predetermined first discharge depth to a predetermined second discharge depth in the entire range of the discharge depth history by a size of the reference range.

9. The overvoltage characteristic evaluation device according to claim 8, wherein: The control unit is configured to determine the concentrated overvoltage range in the reference range. 10 . The overvoltage characteristic evaluation device according to claim 1 , further comprising a temperature chamber having an internal space for receiving the battery, and a temperature of the internal space is detected and adjusted. 11 . The overvoltage characteristic evaluation device according to claim 1 , further comprising an interface unit configured to support communication between the control unit and a user terminal.

12. A method for evaluating an overvoltage characteristic of a battery, the method comprising the following steps: determining a measured capacity history and a measured voltage history indicative of time series changes in capacity and voltage of the battery using sensed information of current and voltage of the battery obtained during a discharge event performed after polarization inducing preconditioning of the battery; determining a first measured voltage curve indicating a correlation between the measured capacity history and the measured voltage history; determining a second measured voltage curve indicating a correlation between a depth of discharge history obtained by normalizing the measured capacity history with respect to a total discharge capacity of the measured capacity history and the measured voltage history; determining a differentiated voltage curve from the second measured voltage curve by differentiating the measured voltage history with respect to the depth of discharge history; as well as Overvoltage characteristic information associated with the polarization inducing pre-processing is determined by comparing the differential voltage curve with a reference differential voltage curve.

13. The overvoltage characteristic evaluation method according to claim 12, wherein: The step of determining the overvoltage characteristic information associated with the polarization induced preprocessing includes determining a concentrated overvoltage range, which is a range in which the differential voltage difference between the differential voltage curve and the reference differential voltage curve is equal to or greater than a threshold difference in the entire range of the discharge depth history.

14. The overvoltage characteristic evaluation method according to claim 13, wherein: The step of determining the overvoltage characteristic information associated with the polarization inducing pre-processing further includes determining an area of ​​a concentrated overvoltage region defined by the concentrated overvoltage range, the differential voltage curve, and the reference differential voltage curve.

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