Battery management device and method

Abstract

A battery management apparatus according to an embodiment of the present disclosure includes: a curve acquisition unit configured to acquire a differential curve representing a correspondence relationship between a voltage of a battery and a differential capacity; and a control unit configured to determine a first point as a starting point of a preset target voltage section of the differential curve, a second point having the highest differential capacity, and a third point having the lowest differential capacity in a voltage section having a voltage higher than or equal to that of the second point in the target voltage section, and diagnosing the state of the battery according to the differential capacities of the first point, the second point, and the third point.

Description

TECHNICAL FIELD

[0001] This application is based on and claims priority to Korean Patent Application No. 10-2024-0001796, filed on January 4, 2024, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

[0002] The disclosure relates to a technology for diagnosing and managing a battery state, and more particularly, to a battery management device and method that diagnose a battery state using characteristics of a differential curve. BACKGROUND

[0003] With the rapid growth in demand for portable electronic products, such as laptop computers and mobile phones, using electric power as a power source, and with the more widespread commercialization of mobile robots, electric bicycles, electric carts, and electric vehicles, research into high-performance secondary batteries capable of repeated charging and discharging is actively being conducted.

[0004] Commercially available secondary batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium secondary batteries, and the like. Among them, lithium secondary batteries have the advantage of free charging and discharging, and have a very low self-discharge rate compared to nickel-based secondary batteries, with almost no memory effect. In addition, lithium secondary batteries have the characteristics of high energy density and high operating voltage, and thus are more intensively researched and more widely used in actual products than other types of secondary batteries.

[0005] In recent years, secondary batteries are widely used not only in small devices such as portable electronic devices, but also in medium- and large-sized devices such as electric vehicles and energy storage systems (ESS).

[0006] Unlike methods of generating energy based on fossil fuels, batteries based on secondary monomers generate energy through electrochemical reactions. Therefore, as the charging / discharging cycle continues or repeats, the performance at the time of initial manufacturing, i.e., the BOL (beginning of life) state, cannot be maintained and gradually deteriorates.

[0007] As a battery is continuously used (charged and discharged), its usability decreases due to the deterioration of capacity and output, and its safety also becomes a risk factor. Therefore, it is necessary to accurately diagnose the current state of the battery for controlling limited use, determining a replacement time, determining an objective price for battery sharing or subscription, and improving the efficiency of battery reuse or recycling.

[0008] Conventional representative methods for diagnosing the condition of a battery monomer include a method of using the behavior characteristics of the differential curve or peak point variation of the battery monomer, and a three-electrode analysis method using a positive and negative coin-type half cell (CHC).

[0009] The conventional methods for diagnosing whether a battery cell is deteriorated using a state of charge, a positive electrode terminal potential, a negative electrode terminal potential, etc. mainly involve artificially manufacturing a negative electrode coin-type half cell, a positive electrode coin-type half cell, etc., using a reference cell having the same specifications as the battery cell to be diagnosed, and comparing its electrical behavior characteristics with a charge / discharge curve of the target cell to determine the positions of the positive and negative electrodes corresponding to the deterioration point. Here, the reference cell refers to a cell in a BOL state, which is not deteriorated.

[0010] However, since these conventional methods require the artificial coin-type half cells to be manufactured for each electrode, a great deal of time is required. In addition, since these conventional methods largely depend on the manual operation of the worker, the accuracy can be reduced due to various human errors such as bias and mistakes.

[0011] Meanwhile, when a battery cell is aged or defective during the manufacturing process, lithium plating (Li-plating) can occur in which cations (Li+) of lithium (Li) supplied to the negative electrode are not quickly absorbed by the negative electrode and are deposited as lithium metal on the negative electrode surface.

[0012] In order to diagnose the occurrence of the conventional lithium plating, a separate method independent of the above-described diagnosis of the state of charge must be additionally applied, and thus, more time is required to diagnose all these problems, and the process also becomes more complicated. SUMMARY

[0013] Technical problem

[0014] The present disclosure aims to solve the problems in the related art, and thus, the present disclosure aims to provide a battery management device and method that can quickly and reliably diagnose the current state of a battery using a differential curve of the battery.

[0015] The technical problems that the present disclosure attempts to solve are not limited to the above-mentioned problems, and those skilled in the art will clearly understand other problems not mentioned from the following description.

[0016] Technical solution

[0017] A battery management device according to one aspect of the present disclosure can include a curve acquisition unit configured to acquire a differential curve representing a correspondence between a voltage of a battery and a differential capacity, and a control unit configured to determine a first point that is a starting point of a preset target voltage section of the differential curve, a second point having a highest differential capacity in the target voltage section, and a third point having a lowest differential capacity in a voltage section higher than or equal to a voltage of the second point in the target voltage section, and diagnose a state of the battery according to the differential capacities of the first point, the second point, and the third point.

[0018] The control unit can be configured to calculate a first differential capacity difference between the first point and the second point, a second differential capacity difference between the second point and the third point, and a differential capacity ratio between the first differential capacity difference and the second differential capacity difference.

[0019] The control unit can be configured to compare the differential capacity ratio with a preset first threshold value, and diagnose whether lithium plating occurs in the battery based on a result of the comparison.

[0020] The control unit can be configured to diagnose that lithium plating occurs in the battery when the differential capacity ratio is lower than or equal to the first threshold value.

[0021] The control unit can be configured to diagnose that lithium plating occurs in the battery when the differential capacity of the second point and the differential capacity of the third point are the same.

[0022] The control unit can be configured to determine the positive electrode potential and the negative electrode potential of the battery according to the differential capacity ratio based on a potential curve preset to represent a correspondence between the differential capacity and the positive electrode potential and the negative electrode potential.

[0023] The control unit can be configured to compare the negative electrode potential with a preset second threshold value, and diagnose whether lithium plating occurs in the battery based on a result of the comparison.

[0024] The control unit can be configured to diagnose that lithium plating occurs in the battery when the negative electrode potential is lower than or equal to the second threshold value.

[0025] The control unit can be configured to determine a positive electrode charge depth and a negative electrode charge depth of the battery based on the positive electrode potential and the negative electrode potential.

[0026] A battery pack according to another aspect of the disclosure can include a battery management device according to an aspect of the disclosure.

[0027] A vehicle according to still another aspect of the disclosure can include a battery management device according to an aspect of the disclosure.

[0028] A battery management method according to still another aspect of the disclosure can include a curve acquisition step of acquiring a differential curve representing a correspondence between a voltage of a battery and a differential capacity, a point determination step of determining a first point that is a start point of a target voltage section of the differential curve, a second point having a highest differential capacity in the target voltage section, and a third point having a lowest differential capacity in a voltage section higher than or equal to a voltage of the second point in the target voltage section, and a diagnosis step of diagnosing a state of the battery according to differential capacities of the first point, the second point, and the third point.

[0029] Beneficial effects

[0030] According to one embodiment of this disclosure, the battery management device has the advantage that it can diagnose the current state of the battery in a non-destructive manner by comparing the differential capacity of points included in the differential curve of the battery.

[0031] In particular, this battery management device has the advantage of being able to specifically diagnose whether lithium plating has occurred in the battery and the depth of charge of the battery.

[0032] The effects of this disclosure are not limited to those described above, and those skilled in the art will clearly understand from the description of the claims other effects not mentioned. Attached Figure Description

[0033] The accompanying drawings illustrate preferred embodiments of the present disclosure and are used together with the foregoing disclosure to further understand the technical features of the present disclosure; therefore, the present disclosure should not be construed as limited to the drawings.

[0034] Figure 1 This is a schematic diagram of a battery management device according to an embodiment of the present disclosure.

[0035] Figure 2 This is a schematic diagram of a first differential curve according to an embodiment of the present disclosure.

[0036] Figure 3 yes Figure 2 An enlarged view of the first differential curve.

[0037] Figure 4 This is a schematic diagram of the second differential curve according to an embodiment of the present disclosure.

[0038] Figure 5 yes Figure 4 An enlarged view of the second differential curve.

[0039] Figure 6 This is a schematic diagram of a potential curve according to an embodiment of the present disclosure.

[0040] Figure 7 This is a schematic diagram of an exemplary configuration of a battery pack including a battery management device according to embodiments of the present disclosure.

[0041] Figure 8 This is a schematic diagram of a vehicle according to another embodiment of the present disclosure.

[0042] Figure 9 This is a schematic diagram of a battery management method according to yet another embodiment of the present disclosure. Detailed Implementation

[0043] It should be understood that the terms used in the specification and the appended claims should not be construed as limited to general and dictionary meanings and should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present disclosure based on the principle that the inventor is allowed to define appropriate terms in order to obtain the best explanation.

[0044] Therefore, the description presented herein is merely a preferred example for the purpose of illustration and is not intended to limit the scope of the present disclosure, and it should be understood that other equivalent substitutions and modifications can be made thereto without departing from the scope of the present disclosure.

[0045] Further, in describing the present disclosure, if it is considered that a detailed description of related known elements or functions will cause ambiguity of the key subject matter of the present disclosure, such detailed description will be omitted herein.

[0046] The terms including ordinal numbers such as "first", "second", etc. can be used to distinguish one element from another among various elements, but are not intended to limit the elements by the terms.

[0047] Throughout the specification, when a part is referred to as "including" or "comprising" any element, unless explicitly stated otherwise, it means that the part can further include other elements, not excluding the other elements.

[0048] Further, throughout the specification, when a part is referred to as "connected" to another part, it is not limited to the case where they are "directly connected", but also includes the case where another element is interposed therebetween.

[0049] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0050] Figure 1 is a diagram schematically illustrating a battery management device 100 according to an embodiment of the present disclosure.

[0051] Referring to Figure 1 , the battery management device 100 can include a curve acquisition unit 110, a control unit 120, and a storage unit 130.

[0052] Here, the battery refers to a single cell including a negative terminal and a positive terminal that are physically separable. For example, a lithium ion battery or a lithium polymer battery can be regarded as a battery. Additionally, the type of the battery can be cylindrical, prismatic, or pouch. Further, the battery can refer to a battery pack, a battery module, or a battery group connected in series and / or in parallel by a plurality of single cells. Hereinafter, for convenience of explanation, the battery is described and explained as a single independent single cell.

[0053] The curve acquisition unit 110 can be configured to acquire a differential curve representing a correspondence between a voltage of the battery and a differential capacity.

[0054] For example, the battery curve is a curve representing a correspondence between voltage (V) and capacity (Q) as the SOC of the battery is charged from a preset starting SOC or 0% to a preset ending SOC or 100%. As another example, the battery curve can represent a correspondence between voltage (V) and capacity (Q) as the SOC of the battery is discharged from a preset starting SOC or 100% to a preset ending SOC or 0%.

[0055] Also, if the battery curve is differentiated with respect to voltage, a differential curve representing a correspondence between differential capacity (dQ / dV) and voltage (V) can be generated.

[0056] For example, there is no particular limitation on the C-rate of charging or discharging used to generate the battery curve. However, it is preferable that the battery should be charged or discharged at a low rate to obtain more accurate battery curve and differential curve. For example, the battery curve can be generated in a process of charging or discharging the battery at 0.05C.

[0057] For example, the curve acquisition unit 110 can directly receive the differential curve of the battery from the outside. That is, the curve acquisition unit 110 can acquire the differential curve by being connected to the outside by wire and / or wirelessly and receiving the differential curve.

[0058] As another example, the curve acquisition unit 110 can directly receive the battery curve of the battery from the outside. Then, the curve acquisition unit 110 can generate the differential curve by differentiating the battery curve with respect to voltage. That is, the curve acquisition unit 110 can acquire the differential curve by being connected to the outside by wire and / or wirelessly to receive the battery curve and directly generate the differential curve from the battery curve.

[0059] As another example, the curve acquisition unit 110 can receive battery information about voltage and capacity of the battery. Also, the curve acquisition unit 110 can generate the battery curve based on the received battery information, and generate the differential curve based on the generated battery curve. That is, the curve acquisition unit 110 can acquire the differential curve by directly generating the differential curve based on the battery information.

[0060] The curve acquisition unit 110 can be connected to communicate with the control unit 120. For example, the curve acquisition unit 110 can be connected to the control unit 120 by wire and / or wirelessly. The curve acquisition unit can transmit the acquired differential curve to the control unit 120.

[0061] Figure 2 is a schematic view of a first differential curve Pa according to an embodiment of the disclosure. In Figure 2In this embodiment, the first differential curve Pa can be represented as an XY curve, where the X-axis is voltage (V) and the Y-axis is differential capacity (dQ / dV). Specifically, the first differential curve Pa is a differential curve that represents the relationship between the voltage and differential capacity of a preset first battery.

[0062] The control unit 120 can be configured to determine a first point as the starting point of a preset target voltage segment RT of the differential curve, a second point having the highest differential capacity in the target voltage segment, and a third point having the lowest differential capacity in a voltage segment with a voltage higher than or equal to the second point.

[0063] Here, the target voltage range RT is part of the entire voltage range of the battery and can be preset by the control unit 120.

[0064] Specifically, the control unit 120 can determine at least one local minimum point in the differential curve. The differential curve may include at least one local minimum point. This is because the differential curve is obtained by differentiating the battery curve with respect to voltage, and the slope of the battery curve (the rate of change of voltage and capacity) is not constant.

[0065] For example, in Figure 2 In one embodiment, the first differential curve Pa may include a first local minimum point m1, a second local minimum point m2, a third local minimum point m3, and a fourth local minimum point m4.

[0066] In addition, the control unit 120 can determine the target local minimum point as the local minimum point whose voltage corresponds to a preset reference voltage among at least one determined local minimum point.

[0067] Specifically, the control unit 120 can determine the target local minimum point as the local minimum point whose corresponding voltage is close to the reference voltage among at least one local minimum points. In other words, the control unit 120 can determine the target local minimum point as the local minimum point whose corresponding voltage is closest to the reference voltage among at least one local minimum points.

[0068] For example, in Figure 2 In this embodiment, the reference voltage is assumed to be preset to 4.0 [V]. Among the four local minimum points m1, m2, m3, and m4 included in the first differential curve Pa, the local minimum point whose corresponding voltage is closest to the reference voltage is the third local minimum point m3. Therefore, the control unit 120 can determine the third local minimum point m3 as the target local minimum point.

[0069] Finally, the control unit 120 can set the voltage segment in the entire voltage range that is higher than or equal to the target voltage corresponding to the target local minimum point as the target voltage segment RT.

[0070] Specifically, the control unit 120 can set a lower limit of the target voltage section RT to the target local minimum point and set an upper limit of the target voltage section RT to an upper limit of the entire voltage section of the battery. That is, the control unit 120 can set a voltage section higher than or equal to the target voltage as the target voltage section RT.

[0071] For example, in an embodiment of FIG. 4, the target voltage (VT) is 4.06 [V]. The control unit 120 can set a voltage section of 4.06 [V] or more and 4.2 [V] or less as the target voltage section RT. Figure 2

[0072] Figure 3 is a zoomed-in view of the first differential curve Pa in FIG. 4. Specifically, Figure 2 is a view of the target voltage section RT zoomed-in on the first differential curve Pa. Figure 3

[0073] In an embodiment of FIG. 4, the control unit 120 can determine the starting point of the target voltage section RT as the first point Pa1. That is, the first point Pa1 can be the target local minimum point included in the first differential curve Pa. Then, the control unit 120 can determine a point having the maximum differential capacity in the target voltage section RT as the second point Pa2. Finally, the control unit 120 can determine a point having the minimum corresponding differential capacity in a voltage section of which the corresponding voltage is higher than or equal to the voltage of the second point Pa2 as the third point Pa3. Figure 3 In an embodiment of FIG. 4, the second point Pa2 is a local maximum point included in the target voltage section RT. However, depending on the embodiment, the target voltage section RT can not include the local maximum point. That is, in a voltage section after the first point Pa1, the differential capacity can not decrease. For example, in a voltage section after the first point Pa1, the rate of change of the differential capacity with respect to the voltage can be 0 or more. In this case, the second point Pa2 can be determined as a point having the maximum differential capacity in the target voltage section RT. Also, the differential capacity of the third point Pa3 can be equal to the differential capacity of the second point Pa2.

[0074] Figure 3 The control unit 120 can be configured to diagnose the state of the battery based on the differential capacities of the first, second, and third points.

[0075] The control unit 120 can be configured to diagnose the state of the battery based on the differential capacities of the first, second, and third points.

[0076] ​​​Specifically, the differential capacity is a value obtained by differentiating the capacity with respect to the voltage, and indicates an instantaneous rate of change of the capacity with respect to the voltage. In other words, the differential capacity is a representative factor in which the sensitive state change of the battery can also be confirmed. Specifically, as the battery deteriorates, the differential capacity of the third point can change more rapidly than the differential capacities of the first and second points. For example, as the battery deteriorates, the degree to which the differential capacity of the third point increases can be greater than the degree to which the differential capacities of the first and second points decrease. Accordingly, the control unit 120 can diagnose the state of the battery by diagnosing the differential capacities of the first to third points, thereby non-destructively diagnosing the current state of the battery.

[0077] For example, the control unit 120 can diagnose whether lithium plating has occurred in the battery based on the differential capacities of the first to third points.

[0078] As another example, the control unit 120 can determine the depth of charge (DOC) of the battery based on the differential capacities of the first to third points. Here, the depth of charge is an index indicating the charge performance of the battery, and is a term indicating the energy storage performance of the battery. For example, as the depth of charge of the battery is greater, more energy can be stored in the battery. Preferably, the control unit 120 can more specifically diagnose the current state of the battery by non-destructively diagnosing the positive electrode depth of charge and the negative electrode depth of charge of the battery.

[0079] The battery management device 100 according to an embodiment of the disclosure has an advantage in that it can explicitly diagnose the current state of the battery in a non-destructive manner by comparing the differential capacities of the three points of the differential curve. Specifically, the battery management device 100 has an advantage in that it can explicitly diagnose whether lithium plating has occurred in the battery and the depth of charge of the battery.

[0080] Meanwhile, the control unit 120 provided in the battery management device 100 can selectively include a processor, an application specific integrated circuit (ASIC), other chipsets, logic circuitry, registers, communication modems, data processing devices, and the like known in the art to perform various control logics implemented in the disclosure. Furthermore, when the control logics are implemented in software, the control unit 120 can be implemented as a set of program modules. At this time, the program modules can be stored in a memory and executed by the control unit 120. The memory can be located inside or outside the control unit 120, and can be connected to the control unit 120 by various well-known means.

[0081] Further, the battery management device 100 can further include a storage unit 130. The storage unit 130 can store data necessary for operations and functions of each component in the battery management device 100, data generated in the process of performing operations or functions, etc. The type of the storage unit 130 is not particularly limited as long as it is an information storage device known to be capable of recording, erasing, updating, and reading data. As an example, the information storage device can include a RAM, a flash memory, a ROM, an EEPROM, a register, etc. Further, the storage unit 130 can store program codes defining processes executable by the control unit 120.

[0082] For example, the curve acquired by the curve acquisition unit 110 can be stored in the storage unit 130. Then, the control unit 120 can access the storage unit 130 to acquire the stored curve.

[0083] Embodiments in which the control unit 120 diagnoses whether lithium plating occurs in the battery based on the differential capacity of the first point to the third point will be specifically described below.

[0084] The control unit 120 can be configured to calculate a first differential capacity difference of the first point and the second point. Also, the control unit 120 can be configured to calculate a second differential capacity difference of the second point and the third point.

[0085] For example, in an embodiment of Figure 3 , the differential capacity difference between the first point and the second point is Da1, and the differential capacity difference between the second point and the third point is Da2.

[0086] The control unit 120 can be configured to calculate a differential capacity ratio of the first differential capacity difference and the second differential capacity difference.

[0087] Specifically, the control unit 120 can calculate a value obtained by dividing the second differential capacity difference by the first differential capacity difference as the differential capacity ratio. For example, in an embodiment of Figure 3 , the control unit 120 can calculate the differential capacity ratio by a calculation formula of "Da2 ÷ Da1" or "Da2 ÷ Da1 × 100". Depending on the calculation formula, the differential capacity ratio can be expressed as a value of 0 to 1 or as a value of 0% to 100%. Hereinafter, for convenience of explanation, the differential capacity ratio will be expressed as a value of 0% to 100%.

[0088] The control unit 120 can be configured to compare the differential capacity ratio with a preset first threshold value.

[0089] Here, the first threshold value can be preset to a value corresponding to the differential capacity ratio of the battery in which lithium plating has occurred. For example, the first threshold value can be preset to a value of 0% or more and 1% or less. Preferably, the first threshold value can be preset to a value of 0% or more and 0.5% or less. More preferably, the first threshold value can be preset to 0.2%.

[0090] Specifically, the control unit 120 can compare the magnitude of the differential capacity ratio with the first threshold value. That is, the control unit 120 can determine whether the differential capacity ratio is less than or equal to the first threshold value, or whether the differential capacity ratio exceeds the first threshold value.

[0091] For example, in the embodiment of Figure 2 and Figure 3 , the differential capacity ratio of the first battery is 76%. The control unit 120 can determine that the differential capacity ratio (76%) of the first battery is greater than or equal to the first threshold value (0.2%).

[0092] The control unit 120 can be configured to diagnose whether lithium plating has occurred in the battery based on the comparison result.

[0093] Specifically, the control unit 120 can be configured to diagnose that lithium plating has occurred in the battery if the differential capacity ratio is less than or equal to the first threshold value.

[0094] In the aforementioned example, since the differential capacity ratio (76%) of the first battery is greater than or equal to the first threshold value (0.2%), the control unit 120 can diagnose that lithium plating has not occurred in the first battery.

[0095] As described above, as the battery performance deteriorates, the differential capacity change at the third point can be greater than the differential capacity changes at the first and second points. In other words, if the battery state has changed to the extent that the differential capacity ratio becomes less than or equal to the first threshold value, it can be diagnosed that lithium metal has been deposited on the negative electrode surface of the battery even without disassembling the battery.

[0096] The battery management device 100 has an advantage in that it can diagnose whether lithium plating has occurred in the battery in a non-destructive manner based on the differential capacity ratio between certain points in the differential curve.

[0097] Specifically, according to the present disclosure, the battery state can be diagnosed by analyzing only the curve of the target voltage section RT in the differential curve. Therefore, the battery management device 100 has an advantage in that it can diagnose the battery state faster and with less use of system resources than when analyzing the entire differential curve.

[0098] Meanwhile, the control unit 120 can be configured to diagnose that lithium plating has occurred in the battery when the differential capacity of the second point is the same as the differential capacity of the third point.

[0099] As described above, depending on the embodiment, the second point can not appear as a local maximum point. In this case, the second point can be determined as a point corresponding to the highest differential capacity in the target voltage section RT. Also, since the second point is not a local maximum point, the differential capacity of the third point and the differential capacity of the second point can be the same.

[0100] For example, if there is no local maximum point in the target voltage section RT, the second point and the third point can be the same. In this case, the voltage of the second point and the third point is the upper limit of the target voltage section RT, and the differential capacity is the maximum differential capacity of the target voltage section RT.

[0101] As another example, if there is no local maximum point in the target voltage section RT, the second point and the third point can be different, but their differential capacities can be the same. Specifically, if the differential capacities of the voltage sections after the second point are all the same, the second point and the third point can be different. In this case, the voltage of the second point (e.g., 4.15 [V]) and the voltage of the third point (e.g., 4.2 [V]) are different, but the differential capacities of the second point and the third point are the maximum differential capacity of the target voltage section RT.

[0102] If the differential capacities of the second point and the third point are the same, the control unit 120 can calculate the second differential capacity difference as 0. Also, since the second differential capacity difference is 0, the control unit 120 can calculate the differential capacity ratio as 0. In this case, since the differential capacity ratio is always less than or equal to the first threshold value, the control unit 120 can be configured to diagnose that lithium plating has occurred in the battery.

[0103] Figure 4 is a schematic view of a second differential curve Pb according to an embodiment of the disclosure. In Figure 4 In an embodiment of

[0104] In an embodiment of Figure 4 In an embodiment of In an embodiment of

[0105] Figure 5 is Figure 4 an enlarged view of a second differential curve Pb. Specifically, Figure 5 is an enlarged view of a target voltage section RT of the second differential curve Pb.

[0106] In an embodiment of Figure 5 , the control unit 120 can determine a starting point of a preset target voltage section RT in the differential curve as a first point Pb1. Then, the control unit 120 can determine a point having a maximum differential capacity in the target voltage section RT as a second point Pb2. Finally, the control unit 120 can determine a point having a minimum corresponding differential capacity in a voltage section having a voltage higher than or equal to the second point Pb2 as a third point Pb3.

[0107] Further, the control unit 120 can calculate a first differential capacity difference (Db1) between the first point and the second point, calculate a second differential capacity difference (Db2) between the second point and the third point, and calculate a differential capacity ratio of the second differential capacity difference (Db2) to the first differential capacity difference (Db1).

[0108] Finally, the control unit 120 can diagnose the state of the second battery based on the calculated differential capacity ratio.

[0109] For example, in an embodiment of Figure 4 and Figure 5 , the differential capacity ratio of the second battery is 42%. The control unit 120 can determine that the differential capacity ratio (42%) of the second battery is greater than or equal to the first threshold value (0.2%). Accordingly, the control unit 120 can diagnose that lithium plating has not occurred in the second battery.

[0110] Embodiments in which the control unit 120 determines the positive and negative charge depths of the battery based on the differential capacities of the first to third points will be specifically described below.

[0111] The control unit 120 can be configured to determine the positive and negative potentials of the battery according to the differential capacity ratio based on a potential curve that is preset to represent a correspondence between the differential capacity and the positive and negative potentials.

[0112] Here, the potential curve can be preset to represent a correspondence between the differential capacity ratio, the positive potential, and the negative potential. Specifically, the positive and negative potentials corresponding to the differential capacity ratio of the battery can be determined in advance by performing experiments using a three-electrode battery or a coin-type half cell (CHC). The control unit 120 can determine the positive and negative potentials corresponding to the differential capacity ratio calculated for the battery by referring to the preset potential curve.

[0113] Figure 6is a potential profile diagram according to an embodiment of the disclosure. Specifically, Figure 6 The potential profile of the first battery is a potential profile preset to correspond to a battery with a charge termination voltage (or upper limit voltage) of 4.2 [V].

[0114] Referring to the foregoing example, the first battery is calculated to have a differential capacity ratio of 76%, and the second battery is calculated to have a differential capacity ratio of 42%. The control unit 120 can determine the positive electrode potential of the first battery to be 4.2335 [V], and the negative electrode potential to be 0.0335 [V]. In addition, the control unit 120 can determine the positive electrode potential of the second battery to be 4.2175 [V], and the negative electrode potential to be 0.0175 [V].

[0115] Specifically, the control unit 120 can be configured to determine the positive electrode charge depth and the negative electrode charge depth of the battery based on the positive electrode potential and the negative electrode potential.

[0116] For example, the first battery can be charged until the positive electrode potential reaches 4.2335 [V], and the negative electrode potential reaches 0.0335 [V]. The control unit 120 can calculate the positive electrode charge amount at which the positive electrode potential reaches 4.2335 [V] by referring to the positive electrode profile corresponding to the first battery. Then, the control unit 120 can determine the calculated positive electrode charge amount as the positive electrode charge depth. Likewise, the control unit 120 can calculate the negative electrode charge amount until the negative electrode potential reaches 0.0335 [V] by referring to the negative electrode profile corresponding to the first battery. Then, the control unit 120 can determine the calculated negative electrode charge amount as the negative electrode charge depth.

[0117] Here, the positive electrode profile corresponding to the battery is a profile indicating the current positive electrode state of the battery, and can represent a correspondence relationship between the positive electrode capacity and the positive electrode potential. For example, a reference positive electrode profile preset for a battery in a BOL (beginning of life) state or a theoretically ideal reference cell is provided, and the positive electrode profile can be prepared by adjusting (or fitting) the reference positive electrode profile to correspond to the current state of the battery. Likewise, the negative electrode profile corresponding to the battery is a profile indicating the current negative electrode state of the battery, and can represent a correspondence relationship between the negative electrode capacity and the negative electrode potential. For example, a reference negative electrode profile preset for a battery in a BOL state or a theoretically ideal reference cell is provided, and the negative electrode profile can be prepared by adjusting (or fitting) the reference negative electrode profile to correspond to the current state of the battery. Since the adjustment process of the reference positive electrode profile and the reference negative electrode profile can employ a conventional method, a detailed description thereof is omitted here.

[0118] The battery management device 100 according to the embodiment of the present disclosure has an advantage in that it can diagnose the current state of the battery from various aspects by determining the positive and negative electrode potentials and the positive and negative electrode charge depths based on the differential capacity ratio. That is, according to the present disclosure, it is possible to not only determine whether lithium plating has occurred, but also provide specific information about the positive and negative electrodes, and thus it is possible to objectively diagnose the state of the battery based on various information.

[0119] Meanwhile, the control unit 120 can be configured to compare the negative electrode potential with a preset second threshold value.

[0120] Here, the second threshold value can be preset to a value corresponding to the battery negative electrode potential in which lithium plating occurs. In general, it is known that when the negative electrode potential is lower than or equal to a predetermined value, a lithium deposition reaction occurs. That is, when the negative electrode potential falls below the second threshold value, a lithium plating phenomenon can occur. For example, the second threshold value can be preset to a value less than or equal to 0 [V]. Preferably, the second threshold value can be preset to a value less than or equal to -0.1 [V]. More preferably, the second threshold value can be preset to -0.1 [V]. Hereinafter, for convenience of explanation, -0.1 [V] is exemplified.

[0121] Specifically, the control unit 120 can compare the magnitude of the negative electrode potential with the second threshold value. That is, the control unit 120 can determine whether the negative electrode potential is less than or equal to the second threshold value or whether the negative electrode potential exceeds the second threshold value.

[0122] For example, in the embodiment of Figure 6 , the negative electrode potential of the first battery is 0.0335 [V] and the negative electrode potential of the second battery is 0.0175 [V]. The control unit 120 can determine that the negative electrode potentials of the first and second batteries are both greater than or equal to the second threshold value (-0.1 [V]).

[0123] The control unit 120 can be configured to diagnose whether lithium plating has occurred in the battery based on the comparison result. That is, the control unit 120 can diagnose whether lithium plating has occurred in the battery using not only the differential capacity ratio of the battery but also the negative electrode potential.

[0124] Specifically, the control unit 120 can be configured to diagnose that lithium plating has occurred in the battery if the negative electrode potential is less than or equal to the second threshold value.

[0125] In the previous example, since the negative electrode potential of the first battery (0.0335 [V]) is greater than or equal to the second threshold value (-0.1 [V]), the control unit 120 can diagnose that lithium plating has not occurred in the first battery. Also, since the negative electrode potential of the secondary battery (0.0175 [V]) is greater than or equal to the second threshold value (-0.1 [V]), the control unit 120 can diagnose that lithium plating has not occurred in the secondary battery.

[0126] That is, the battery management device 100 can diagnose the battery state more objectively and complementarily by diagnosing the battery state based on the differential capacity ratio and / or the negative electrode potential.

[0127] The battery management device 100 according to the disclosure can be applied to a BMS (Battery Management System). That is, the BMS according to the disclosure can include the above-described battery management device 100. In this configuration, at least some components of the battery management device 100 can be implemented by supplementing or adding the functions of components included in a conventional BMS. For example, the curve acquisition unit 110, the control unit 120, and the storage unit 130 of the battery management device 100 can be implemented as components of the BMS.

[0128] Further, the battery management device 100 according to the disclosure can be provided in a battery pack. That is, the battery pack according to the disclosure can include the above-described battery management device 100 and one or more battery cells. Further, the battery pack can further include electrical equipment (a relay, a fuse, etc.) and a housing.

[0129] Figure 7 A diagram showing an exemplary configuration of a battery pack including the battery management device 100 according to an embodiment of the disclosure is shown.

[0130] The positive electrode terminal of the battery 11 can be connected to the positive electrode terminal P+ of the battery pack 10, and the negative electrode terminal of the battery 11 can be connected to the negative electrode terminal P- of the battery pack 10.

[0131] The measurement unit 12 can be connected to the first sensing line SL1, the second sensing line SL2, and the third sensing line SL3. Specifically, the measurement unit 12 can be connected to the positive electrode terminal of the battery 11 through the first sensing line SL1, and can be connected to the negative electrode terminal of the battery 11 through the second sensing line SL2. The measurement unit 12 can measure the voltage of the battery 11 based on the voltage measured at each of the first sensing line SL1 and the second sensing line SL2.

[0132] Further, the measurement unit 12 can be connected to an ammeter A through a third sensing line SL3. For example, the ammeter A can be an ammeter or a shunt resistor capable of measuring a charging current and a discharging current of the battery 11. The measurement unit 12 can calculate a charging amount by measuring the charging current of the battery 11 through the third sensing line SL3. Further, the measurement unit 12 can calculate a discharging amount by measuring the discharging current of the battery 11 through the third sensing line SL3.

[0133] For example, the curve acquisition unit 110 can receive a differential curve representing a correspondence relationship between the voltage and the differential capacity of the battery 11 from the measurement unit 12.

[0134] As another example, the curve acquisition unit 110 can receive a battery curve representing a correspondence relationship between the voltage and the capacity of the battery 11 from the measurement unit 12. Then, the curve acquisition unit 110 can differentiate the battery curve with respect to the voltage to generate a differential curve.

[0135] As still another example, the curve acquisition unit 110 can receive battery information about the voltage and the capacity of the battery 11 from the measurement unit 12. Then, the curve acquisition unit 110 can generate a battery curve and a differential curve according to the received battery information.

[0136] An external device can be connected to the positive terminal P+ and the negative terminal P- of the battery pack 10. For example, the external device can be a charging device or a load. Further, the positive terminal of the battery 11, the positive terminal P+ of the battery pack 10, the external device, the negative terminal P- of the battery pack 10, and the negative terminal of the battery 11 can be electrically connected.

[0137] Figure 8 is a schematic view of a vehicle 700 according to another embodiment of the disclosure.

[0138] Referring to Figure 8 The battery pack according to an embodiment of the disclosure can be included in a vehicle 800 such as an electric vehicle (EV) or a hybrid vehicle (HV). Further, the battery pack 810 can supply power to a motor through an inverter provided in the vehicle 800, thereby driving the vehicle 800. Here, the battery pack 810 can include the battery management device 100. That is, the vehicle 800 can include the battery management device 100. In this case, the battery management device 100 can be an on-vehicle device included in the vehicle 800.

[0139] Figure 9 is a schematic view of a battery management method according to still another embodiment of the disclosure.

[0140] Referring to Figure 9 The battery management method can include a curve acquisition step (S100), a point determination step (S200), and a diagnosis step (S300).

[0141] Preferably, each step of the battery management method can be performed by the battery management device 100. Hereinafter, for the convenience of explanation, the overlapping content with the foregoing will be omitted or briefly described.

[0142] The curve acquisition step (S100) is a step of acquiring a differential curve representing a correspondence relationship between a battery voltage and a differential capacity, and can be performed by the curve acquisition unit 110.

[0143] For example, the curve acquisition unit 110 can directly receive the differential curve of the battery from the outside. That is, the curve acquisition unit 110 can acquire the differential curve by being connected to the outside and receiving the differential curve through wired and / or wireless.

[0144] As another example, the curve acquisition unit 110 can directly receive the battery curve of the battery from the outside. Then, the curve acquisition unit 110 can generate the differential curve by differentiating the battery curve with respect to the voltage. That is, the curve acquisition unit 110 can acquire the differential curve by receiving the battery curve through wired and / or wireless connection with the outside and generating the differential curve directly from the battery curve.

[0145] As another example, the curve acquisition unit 110 can receive battery information about the voltage and the capacity of the battery. In addition, the curve acquisition unit 110 can generate the battery curve based on the received battery information, and generate the differential curve based on the generated battery curve. That is, the curve acquisition unit 110 can acquire the differential curve by generating the differential curve directly based on the battery information.

[0146] The point determination step (S200) is a step of determining a first point that is a starting point of a preset target voltage section RT of the differential curve, a second point having the highest differential capacity in the target voltage section, and a third point having the smallest differential capacity in a voltage section higher than or equal to the voltage of the second point, and can be performed by the control unit 120.

[0147] For example, in the embodiment of Figure 3 , the control unit 120 can determine the starting point of the target voltage section RT as the first point Pa1. Then, the control unit 120 can determine the point having the maximum differential capacity in the target voltage section RT as the second point Pa2. Finally, the control unit 120 can determine the point having the smallest corresponding differential capacity in the voltage section higher than or equal to the voltage of the second point Pa2 as the third point Pa3.

[0148] As another example, in the embodiment of Figure 5In an embodiment of the above, the control unit 120 can determine the start point of the preset target voltage section RT in the differential curve as the first point Pa1. Then, the control unit 120 can determine the point having the maximum differential capacity in the target voltage section RT as the second point Pa2. Finally, the control unit 120 can determine the point having the minimum corresponding differential capacity in the voltage section higher than or equal to the voltage of the second point Pa2 as the third point Pa3.

[0149] The diagnosis step (S300) is a step for diagnosing the battery state based on the differential capacities of the first point, the second point, and the third point, and can be performed by the control unit 120.

[0150] For example, the control unit 120 can diagnose whether lithium plating has occurred in the battery based on the differential capacities of the first point to the third point. Specifically, the control unit 120 can be configured to calculate a first differential capacity difference of the first point and the second point, and a second differential capacity difference of the second point and the third point. In addition, the control unit 120 can be configured to calculate a differential capacity ratio of the first differential capacity difference and the second differential capacity difference. Finally, the control unit 120 can diagnose whether lithium plating has occurred in the battery based on a comparison result of the calculated differential capacity ratio with a preset first threshold value.

[0151] As another example, the control unit 120 can determine the positive electrode potential and the negative electrode potential of the battery based on the calculated differential capacity ratio. In addition, the control unit 120 can determine the positive electrode charge depth of the battery according to the determined positive electrode potential, and can determine the negative electrode charge depth of the battery according to the determined negative electrode potential.

[0152] As another example, the control unit 120 can diagnose whether lithium plating has occurred in the battery based on a comparison result of the determined negative electrode potential with a preset second threshold value.

[0153] The above-described embodiments of the present disclosure can be implemented not only by devices and methods but also by programs implementing functions corresponding to configurations of the embodiments of the present disclosure or recording media recording the programs. A person skilled in the art can easily implement the program or the recording medium according to the description of the above-described embodiments.

[0154] The present disclosure has been described in detail above. However, although these detailed descriptions and specific examples indicate preferred embodiments of the present disclosure, they are given by way of example only, as various changes and modifications obvious to those skilled in the art from these detailed descriptions will be made within the scope of the present disclosure.

[0155] In addition, those skilled in the art can make many substitutions, modifications and changes to the above disclosure without departing from the technical aspects of the disclosure, and the disclosure is not limited to the above embodiments and drawings, and each embodiment can be selectively combined in whole or in part to allow various modifications.

[0156] (Reference numeral description)

[0157] 10: battery pack

[0158] 11: battery

[0159] 12: measurement unit

[0160] 100: battery management device

[0161] 110: curve acquisition unit

[0162] 120: control unit

[0163] 130: storage unit

[0164] 800: vehicle

[0165] 810: battery pack

Claims

1. A battery management apparatus comprising: a curve acquisition unit configured to acquire a differential curve representing a correspondence between a voltage and a differential capacity of a battery; and a control unit configured to determine a first point that is a starting point of a preset target voltage section of the differential curve, a second point having a highest differential capacity in the target voltage section, and a third point having a lowest differential capacity in a voltage section higher than or equal to a voltage of the second point in the target voltage section, and diagnose a state of the battery from differential capacities of the first point, the second point, and the third point.

2. The battery management apparatus according to claim 1, wherein the control unit configured to calculate a first differential capacity difference between the first point and the second point, a second differential capacity difference between the second point and the third point, and a differential capacity ratio between the first differential capacity difference and the second differential capacity difference.

3. The battery management apparatus according to claim 2, wherein the control unit configured to compare the differential capacity ratio with a preset first threshold value, and diagnose whether lithium plating occurs in the battery based on a result of the comparison.

4. The battery management apparatus according to claim 3, wherein the control unit configured to diagnose that lithium plating occurs in the battery when the differential capacity ratio is lower than or equal to the first threshold value.

5. The battery management apparatus according to claim 1, wherein the control unit configured to diagnose that lithium plating occurs in the battery when a differential capacity of the second point is the same as a differential capacity of the third point.

6. The battery management apparatus according to claim 2, wherein the control unit configured to determine a positive electrode potential and a negative electrode potential of the battery from the differential capacity ratio based on a preset potential curve representing a correspondence between a differential capacity and the positive electrode potential and the negative electrode potential.

7. The battery management apparatus according to claim 6, wherein the control unit configured to compare the negative electrode potential with a preset second threshold value, and diagnose whether lithium plating occurs in the battery based on a result of the comparison.

8. The battery management apparatus according to claim 7, wherein the control unit configured to diagnose that lithium plating occurs in the battery when the negative electrode potential is lower than or equal to the second threshold value.

9. The battery management apparatus according to claim 6, wherein the control unit configured to determine a positive electrode charge depth and a negative electrode charge depth of the battery based on the positive electrode potential and the negative electrode potential.

10. A battery pack including the battery management apparatus according to any one of claims 1 to 9.

11. A vehicle including the battery management apparatus according to any one of claims 1 to 9.

12. A battery management method comprising: a curve acquisition step of acquiring a differential curve representing a correspondence between a voltage and a differential capacity of a battery; a point determination step for determining: a first point that is a starting point of a predetermined target voltage section of the differential curve, a second point that has the highest differential capacity, and a third point that has the lowest differential capacity in a voltage section higher than or equal to the voltage of the second point in the target voltage section; and a diagnosis step for diagnosing a state of the battery based on the differential capacities of the first point, the second point, and the third point.

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