Battery system diagnostic device and method

Abstract

Disclosed is a battery diagnostic technology capable of effectively diagnosing a defective battery cell among a plurality of battery cells included in a battery system at an early stage. The battery system diagnostic device diagnoses a battery system including a plurality of battery cells having electrode tabs therein, and includes: a cell measurement unit configured to measure voltage or current for each of the plurality of battery cells; and a processor configured to calculate the state of health (SOH) for each battery cell multiple times over time using the voltage or current measured by the cell measurement unit, and detect a battery cell having a defect in the electrode tab among the plurality of battery cells based on the multiple calculated SOHs for each battery cell.

Description

Technical Field

[0001] This application claims priority from Korean Patent Application No. 10-2021-0004822 filed in Korea on January 13, 2021, the disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a battery diagnosis technology, and more particularly, to a battery diagnosis technology capable of diagnosing a defective battery cell in a state of a battery system including a plurality of battery cells. Background Art

[0003] Currently commercialized secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium secondary batteries, etc. Among them, lithium secondary batteries have attracted much attention because they ensure free charge and discharge due to substantially no memory effect compared to nickel-based secondary batteries, as well as very low discharge rate and high energy density.

[0004] Lithium secondary batteries primarily use lithium-based oxides and carbon materials as positive and negative electrode active materials, respectively. They also include an electrode assembly, which includes a positive plate and a negative plate coated with positive and negative active materials, respectively, with a separator interposed between the positive and negative plates; and an exterior, or battery case, which encloses the electrode assembly and electrolyte.

[0005] Generally, lithium secondary batteries can be classified into can-type secondary batteries in which the electrode assembly is built into a metal can and pouch-type secondary batteries in which the electrode assembly is built into a pouch of an aluminum laminate sheet, based on their external shape. In particular, pouch-type secondary batteries tend to be more widely used due to their advantages such as easy stacking and light weight.

[0006] The pouch-type secondary battery may be manufactured by injecting an electrolyte in a state where an electrode assembly is accommodated in a pouch exterior and then sealing the pouch exterior.

[0007] Figure 1 is an exploded perspective view showing a general pouch-type secondary battery, and Figure 2 It shows Figure 1 A perspective view of a pouch-type secondary battery.

[0008] like Figure 1 and Figure 2 As shown, the pouch-type secondary battery 1 may include an electrode assembly 20 and a pouch exterior 30 for accommodating the electrode assembly 20 .

[0009] Here, the electrode assembly 20 has a basic structure including a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, and can be accommodated in the internal space I formed inside the bag outer 30. At this time, the bag outer 30 can be formed with an upper bag 31 and a lower bag 32, and a sealing portion S is provided on the outer peripheral surfaces of the upper bag 31 and the lower bag 32 so that the sealing portions S adhere to each other to seal the internal space I in which the electrode assembly 20 is accommodated.

[0010] Here, at least one positive electrode tab 11 and at least one negative electrode tab 12 may extend from the positive electrode plate and the negative electrode plate, respectively. Furthermore, the positive electrode tab 11 and the negative electrode tab 12 may be coupled to plate-shaped electrode leads, namely, a plate-shaped positive electrode lead 41 and a plate-shaped negative electrode lead 42, respectively. Furthermore, a portion of the positive electrode lead 41 and a portion of the negative electrode lead 42 may be exposed outside the pouch exterior 30 to provide an externally configured electrode terminal for electrical connection to, for example, another secondary battery or an external device.

[0011] As the fields of application of secondary batteries have expanded, in recent years, secondary batteries are becoming widely used not only in small devices such as portable electronic devices but also in medium and large devices such as vehicles and energy storage systems (ESS) for driving or energy storage. In the case of such medium and large devices, in order to increase output or capacity, a large number of secondary batteries can be electrically connected in series and / or in parallel. In particular, in the case of an energy storage system, a very large number of secondary batteries can be included. For example, the energy storage system may include a plurality of battery racks, and each battery rack may be configured to accommodate a plurality of battery modules in a rack frame. In addition, each battery module may include several secondary batteries, and each secondary battery may be referred to as a battery cell. Therefore, the energy storage system may include a very large number of battery cells, for example, thousands to tens of thousands of battery cells.

[0012] In the case of such a battery system, it is very important to diagnose the status of each battery cell. However, as the number of battery cells included therein increases, it is not easy to diagnose the status of a specific battery cell and detect a battery cell with a defect. In addition, there can be many different types of faults for a battery cell. For example, various problems may occur in a battery cell, such as external damage, separator damage, metal foreign matter formation, electrolyte leakage, and tab defects. Among them, a tab defect can be a type of defect that occurs when at least one positive electrode tab 11 or negative electrode tab 12, i.e., electrode tab 10, provided inside a battery cell is disconnected or causes a contact error. If such a tab defect occurs, the performance of the corresponding battery cell may deteriorate or may fail, and thus the performance and reliability of the battery system may deteriorate as a whole. In addition, if a problem such as a tab defect occurs in a specific battery cell, that battery cell may catch fire and cause a fire in the entire battery system.

[0013] Therefore, it is very important to identify which battery cell has a problem and what type of defect has occurred among the large number of battery cells included in a battery system. In particular, when a defective cell occurs, it is very important to diagnose such a defective cell at an early stage. However, an effective method for diagnosing such a defective battery cell at an early stage, or even diagnosing a specific defect type, has not yet been proposed. Summary of the Invention

[0014] Technical issues

[0015] The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is committed to providing a battery system diagnostic device and method that can effectively diagnose defective battery cells among multiple battery cells included in a battery system at an early stage, and a battery system including the battery system diagnostic device.

[0016] These and other objects and advantages of the present disclosure can be understood from the following detailed description and will become more fully apparent from the exemplary embodiments of the present disclosure.In addition, it will be easily understood that the objects and advantages of the present disclosure can be achieved by the means shown in the appended claims and their combinations.

[0017] Technical Solution

[0018] In one aspect of the present disclosure, a battery system diagnostic device is provided, which diagnoses a battery system including a plurality of battery cells, each of which has an electrode tab. The device includes: a cell measuring unit configured to measure a voltage or a current for each of the plurality of battery cells; and a processor configured to calculate the SOH for each battery cell multiple times over time by using the voltage or current measured by the cell measuring unit, and detect a battery cell having a defect in the electrode tab among the plurality of battery cells based on the SOH of each battery cell calculated multiple times.

[0019] Here, the processor may be configured to compare the SOH calculation value with a threshold value so that a disconnection defect and an incomplete contact defect are separately detected as defects of the electrode tab.

[0020] In addition, when the SOH calculation value is equal to or less than the threshold value for a continuous period exceeding a first criterion number of times, the processor may be configured to detect that the corresponding battery cell has a disconnection defect.

[0021] In addition, when the number of times the SOH calculation value switches up / down relative to the threshold value continuously exceeds a second criterion number, the processor may be configured to detect that the corresponding battery cell has an incomplete contact defect.

[0022] Additionally, the processor may be configured to identify whether the number of up / down switches is increasing or decreasing.

[0023] In addition, the threshold value may be set based on the SOH of at least some of the plurality of battery cells.

[0024] In addition, the processor may be configured to detect a defective battery cell by distinguishing a charging process from a discharging process for each battery cell.

[0025] In addition, the processor may be configured to set a precondition for calculating the SOH for each battery cell such that the precondition for the charging process and the precondition for the discharging process are set differently from each other.

[0026] In another aspect of the present disclosure, a battery system is provided. The battery system includes the battery system diagnostic device according to the present disclosure.

[0027] In another aspect of the present disclosure, a battery system diagnostic method is provided, which diagnoses a battery system including multiple battery cells, each of which has an electrode tab. The method includes: measuring voltage or current for each of the multiple battery cells; calculating SOH for each battery cell multiple times over time by using the voltage or current measured in the measuring step; and detecting a battery cell with a defect in the electrode tab among the multiple battery cells based on the SOH of each battery cell calculated multiple times in the calculating step.

[0028] Beneficial effects

[0029] According to the present disclosure, in a battery system including a plurality of battery cells, a defective battery cell can be effectively diagnosed.

[0030] In particular, according to an embodiment of the present disclosure, a battery cell having a problem in an electrode tab among internal components may be quickly detected.

[0031] Furthermore, according to the embodiments of the present disclosure, it is possible to specifically classify the kinds of problems that have occurred in the electrode tab.

[0032] Therefore, according to embodiments of the present disclosure, appropriate follow-up measures such as separation, repair, replacement, etc. may be performed for defective battery cells, particularly battery cells having abnormalities in electrode tabs.

[0033] In addition, according to the embodiments of the present disclosure, since specific information about the defect type of the battery cell can be obtained, the battery cell manufacturing process can be appropriately modified based on the obtained information. Therefore, in this case, the defect rate of the battery cell can be reduced.

[0034] In addition, the present disclosure may have various other effects, and these effects may be described in more detail below.In addition, with respect to each component, if any effect can be easily understood by those skilled in the art, such effect will not be described in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, are used to provide further understanding of the technical features of the present disclosure. Therefore, the present disclosure is not to be construed as being limited to the accompanying drawings.

[0036] Figure 1 is an exploded perspective view showing a general pouch-type secondary battery.

[0037] Figure 2 It shows Figure 1 A perspective view of a pouch-type secondary battery.

[0038] Figure 3 is a block diagram schematically illustrating a functional configuration of a battery system diagnosis device according to an embodiment of the present disclosure.

[0039] Figure 4 is a graph showing the SOH calculated by the processor according to an embodiment of the present disclosure for any one battery cell together with a threshold value to be compared therewith.

[0040] Figure 5 is a graph showing SOH calculated by the processor according to an embodiment of the present disclosure for another battery cell together with a threshold value to be compared therewith.

[0041] Figure 6 is a graph showing SOH calculated for yet another battery cell by the processor according to an embodiment of the present disclosure.

[0042] Figure 7 is a graph showing calculated SOH values ​​of several battery cells included in a battery system according to an embodiment of the present disclosure.

[0043] Figure 8 is a flowchart for schematically illustrating a battery system diagnosis method according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0044] 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 used in the specification and the appended claims should not be interpreted as limited to the general and dictionary meanings, but should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to appropriately define the terms to obtain the best explanation.

[0045] Therefore, the descriptions presented herein are merely preferred examples for illustrative purposes only and are not intended to limit the scope of the present disclosure, so it should be understood that other equivalents and modifications may be made thereto without departing from the scope of the present disclosure.

[0046] Figure 3 is a block diagram schematically illustrating a functional configuration of a battery system diagnosis device according to an embodiment of the present disclosure.

[0047] like Figure 3 As shown, the battery system may include a plurality of battery cells 1. Here, the battery cell 1 may refer to a secondary battery. The secondary battery may be one of the Figure 1 and Figure 2The illustrated pouch-type secondary battery has an electrode assembly 20 housed in a pouch exterior 30. Alternatively, the secondary battery may be a can-type secondary battery in which the electrode assembly is housed in a cylindrical or prismatic metal can. The battery cell 1 to be diagnosed by the battery system diagnostic apparatus of the present disclosure may be selected from various secondary batteries known as of the filing date of this application.

[0048] In particular, the battery cell 1 may include an electrode tab 10 therein. For example, referring to Figure 1 The electrode assembly 20 of the battery cell 1 may include at least one positive electrode plate and at least one negative electrode plate. Furthermore, a positive electrode tab 11 and a negative electrode tab 12 may be provided to the positive electrode plate and the negative electrode plate, respectively. Furthermore, the positive electrode tab 11 may be connected to the positive electrode lead 41, and the negative electrode tab 12 may be connected to the negative electrode lead 42. This is well known as of the filing date of this application, and therefore the internal configuration of the battery cell 1 will not be described in detail here.

[0049] A battery system may include a plurality of such secondary batteries (battery cells 1). That is, a battery system is a system including a plurality of battery cells 1 and may refer to a system configured to charge and discharge electricity. A battery system may include various types of systems such as battery modules, battery packs, battery racks, and energy storage systems (ESS). In particular, in a battery system, a plurality of secondary batteries may be electrically connected to each other in series and / or in parallel.

[0050] The battery system diagnosis device according to the present disclosure can be considered as a device for diagnosing a battery system including a plurality of battery cells 1 having electrode tabs therein as described above.

[0051] In particular, the battery system diagnosis apparatus according to the present disclosure may include a cell measurement unit 100 and a processor 200 .

[0052] The cell measurement unit 100 can be configured to measure the voltage or current for each of the plurality of battery cells 1 included in the battery system. For example, the cell measurement unit 100 may include a voltage sensor and may be configured to measure the voltage at both ends of each battery cell 1 included in the battery system. Alternatively, the cell measurement unit 100 may include a current sensor and may be configured to measure the current flowing in each battery cell 1. Here, the cell measurement unit 100 may measure only one of the voltage or the current of each battery cell 1, or may be configured to measure both the voltage and the current of each battery cell 1.

[0053] In addition, for each battery cell 1 , the cell measuring unit 100 may be configured to measure battery characteristics other than voltage or current, such as temperature, charging time, discharging time, or the number of charge / discharge cycles of the battery cell 1 .

[0054] The cell measuring unit 100 may be configured to measure characteristics of all battery cells 1 included in the battery system, for example, the voltages of all battery cells 1. However, the present disclosure is not necessarily limited to this configuration, and the cell measuring unit 100 may be configured to measure voltage or current only for some battery cells 1 among the plurality of battery cells 1 included in the battery system.

[0055] The battery system diagnostic apparatus according to the present disclosure can employ various battery measuring devices known at the filing date of the present application as the cell measuring unit 100 of the present disclosure. Therefore, the cell measuring unit 100 will not be described in detail here.

[0056] The processor 200 may be electrically connected to the cell measuring unit 100 and receive measurement data from the cell measuring unit 100. In particular, since the cell measuring unit 100 may measure a voltage or a current for each of a plurality of battery cells 1, the processor 200 may receive information about the voltage or current measured in this manner for each battery cell 1 from the cell measuring unit 100.

[0057] In addition, the processor 200 can calculate the state of health (SOH) for each battery cell 1 by using the voltage measurement value or current measurement value of each battery cell 1 transmitted as described above. Here, the SOH of each battery cell 1 means the state of health (SOH) and can be calculated based on the voltage or current of the battery cell 1. The SOH calculation method is widely known in various forms as of the filing date of this application, and therefore will not be described in detail here. In addition, in the battery system diagnostic device according to the present disclosure, the processor 200 can adopt the SOH calculation method known as of the filing date of this application to calculate the SOH.

[0058] The processor 200 may calculate the SOH for each battery cell 1 multiple times. In particular, the processor 200 may be configured to calculate the SOH for each battery cell 1 multiple times over time. For example, the processor 200 may be configured to calculate the SOH for each battery cell 1 daily, weekly, or monthly. Alternatively, the processor may be configured to calculate the SOH for each battery cell 1 each time the number of cycles increases by a predetermined number of times. For example, the processor 200 may be configured to calculate the SOH for each battery cell 1 each time the number of cycles increases by 10.

[0059] Therefore, since the processor 200 obtains SOH calculation results over time for each battery cell 1, the processor 200 may have a plurality of SOH calculation results for each battery cell 1. For example, the processor 200 may have 50 SOH calculation results for each battery cell 1 within a predetermined period.

[0060] In addition, the processor 200 may be configured to detect a defective battery cell 1 based on the multiple calculated SOHs of each battery cell 1. That is, the processor 200 may be configured to obtain multiple SOH calculation results for each battery cell 1 and detect which battery cell 1 has a problem among the multiple battery cells 1 included in the battery system by using the multiple obtained SOH calculation results.

[0061] In particular, the processor 200 may be configured to detect a battery cell 1 having a defect in an electrode tab by using the SOH calculation result for each battery cell 1. For example, Figure 3 As shown, when a plurality of battery cells 1 are included in the battery system, the processor 200 may diagnose which battery cell 1 among the plurality of battery cells 1 has a defect in the electrode tab.

[0062] According to this configuration of the present disclosure, defective battery cells can be diagnosed early by using the SOH of each battery cell 1. In particular, according to this configuration, battery cells 1 having defects in the electrode tabs 10 can be accurately detected at an early stage. Therefore, problems caused by defects in the electrode tabs 10, such as overall performance degradation of the battery system, malfunction, or fire, can be effectively prevented.

[0063] The processor 200 may optionally include a central processing unit (CPU), an application specific integrated circuit (ASIC), a chipset, a logic circuit, a register, a communication modem, a data processing device, etc., as known in the art, to run the various control logics executed in the present disclosure, or these terms may be used to express them. In addition, when the control logic is implemented in software, the processor 200 may be implemented as a set of program modules. In this case, the program modules may be stored in an internal memory or an external memory module 400, etc. and executed by the processor 200. The memory module 400 may be provided inside or outside the processor 200 and may be connected to the processor 200 by various well-known means.

[0064] In particular, if a control device called a microcontroller unit (MCU) or a battery management system (BMS) is included in the battery system, the processor 200 may be implemented by a component such as the provided MCU or BMS.

[0065] Meanwhile, in this specification, terms such as “for” or “configured to” for the operation or function of the processor 200 may include the meaning of “programmed to”.

[0066] In addition, the battery system diagnostic device according to the present disclosure may further include: Figure 3 Notification unit 300 is shown.

[0067] The notification unit 300 may be configured to send the detection results performed by the processor 200 to a user or the like. For example, the notification unit 300 may include a display monitor, a speaker, a warning light, etc., and display the defective cell detection results to the user in various ways such as visual and auditory methods. In particular, the notification unit 300 may be configured to send information to the user about which battery cell 1 among the multiple battery cells 1 included in the battery system has a defect in the electrode terminal tab, such as identification information or location information of the defective battery cell. In addition, the notification unit 300 may be connected to various wired or wireless communication networks known on the filing date of this application, and may be connected to the user's mobile terminal or an external server. In this case, the notification unit 300 may send the defective cell detection information to the portable terminal or server via the communication network.

[0068] In addition, the battery system diagnostic device according to the present disclosure may further include: Figure 3 Memory cell 400 is shown.

[0069] The memory unit 400 can store programs and data necessary for the cell measurement unit 100 or the processor 200 to perform their functions. Specifically, the memory unit 400 can store data or programs necessary for at least some components of the battery system diagnostic apparatus according to an embodiment of the present disclosure to perform operations and functions, or data generated during the execution of operations and functions. For example, the memory unit 400 can store multiple SOH calculation values ​​measured for each battery cell 1 at a time.

[0070] The memory unit 400 may employ any information storage means known in the art that can write, erase, update, and read data without restriction. Examples of such information storage means include RAM, flash memory, ROM, EEPROM, registers, and the like. Furthermore, the memory unit 400 may store program code defining processes executable by the cell measurement unit 100 and / or the processor 200.

[0071] The processor 200 may be configured to compare the calculated SOH value with a threshold value. Here, the threshold value is a value to be compared with the calculated SOH value and may be a criterion value for determining whether the calculated SOH value of the corresponding battery cell 1 is normal. Specifically, the threshold value may be considered an SOH value capable of distinguishing whether an electrode tab defect has occurred in the corresponding battery cell 1. The threshold value may be expressed as a specific value or as a specific range.

[0072] The threshold value may be pre-stored in the processor 200 itself or in the memory unit 400 for use by the processor 200 .

[0073] Furthermore, multiple thresholds can be set based on the passage of time. That is, the SOH of each battery cell 1 is calculated multiple times over time, and a threshold corresponding to each SOH calculated in this manner can be set. For example, when the SOH is calculated for each battery cell 1 on a monthly basis, such as January, February, March, etc., thresholds such as a January threshold, a February threshold, a March threshold, etc. can also be set on a monthly basis. In this case, the thresholds can be set differently from each other, but at least some thresholds can be set identically.

[0074] The processor 200 can diagnose defects in the electrode tabs based on the comparison result between the SOH calculation value and the threshold value. In particular, the processor 200 can be configured to detect whether the defect of the electrode tab is a disconnection defect or an incomplete contact defect. Here, the disconnection defect may mean a state in which one or more electrode tabs 10 included in the battery cell 1 are completely cut off at a specific portion. For example, in a battery cell 1 including ten electrode tabs 10, the disconnection defect may be a state in which at least one electrode tab 10 is completely cut off. An incomplete contact defect may mean a state in which one or more electrode tabs 10 included in the battery cell 1 are cut off at a specific portion and then repeatedly contacted. For example, an incomplete contact defect may mean a state in which a cut-off portion exists in at least one electrode tab 10 but contact occurs intermittently at the cut-off portion.

[0075] According to this configuration of the present disclosure, the electrode tab defect in the battery cell 1 is detected using the SOH calculation value, and even the type of the electrode tab defect can be separately specifically diagnosed. Therefore, in this case, more appropriate measures can be taken according to the type of the electrode tab defect.

[0076] In particular, since an incomplete contact defect is a state in which the severed portion of the electrode tab 10 repeatedly attaches and detaches, it can be predicted that a physical external force is being applied to the electrode tab 10 or the battery cell 1. Therefore, in this case, a more appropriate action can be taken with respect to the external force applied to the corresponding battery cell 1. For example, when a battery cell 1 with an incomplete contact defect exists, the corresponding situation can be notified to the user via the notification unit 300. At this point, the user can identify the cause of the external force and take appropriate measures to eliminate the cause of the external force, such as stopping the battery system or improving the fixing force of the battery rack frame.

[0077] In this embodiment, the processor 200 may be configured to determine whether the situation where the calculated SOH value is less than or equal to the threshold value continues to exceed the first criterion number of times. In addition, when the situation where the calculated SOH value is less than or equal to the threshold value continues to exceed the first criterion number of times, the processor 200 may be configured to detect the corresponding battery cell 1 as having a disconnection defect. Figure 4 This is described in more detail.

[0078] Figure 4 is a graph showing the SOH calculated by the processor 200 for any one battery cell 1 together with a threshold value to be compared therewith according to an embodiment of the present disclosure.

[0079] refer to Figure 4 , a graph indicating the SOH calculated for a specific battery cell 1 during a predetermined period, that is, between d1 and d2, is indicated by B1. In particular, in graph B1, the SOH values ​​calculated for the period between d1 and d2 are indicated by points, and such points are connected by lines.

[0080] In addition, Figure 4 , the threshold value to be compared with the SOH calculated value B1 is indicated by A1. In particular, the threshold value A1 may be set to correspond to each of the SOH calculated values ​​during the period from d1 to d2 so as to be compared with the plurality of SOH calculated values, as shown in FIG. Figure 4 As shown. In addition, the threshold value A1 can be configured to change during the period between d1 and d2, rather than remain unchanged. That is, the threshold value corresponding to each calculation cycle of the SOH can be configured differently.

[0081] In this embodiment, the processor 200 can determine whether the calculated SOH B1 is equal to or less than the threshold value A1. In addition, if there is a part where the SOH calculated value B1 is equal to or less than the threshold value A1, the processor 200 can determine whether the situation where the SOH calculated value B1 is equal to or less than the threshold value A1 continues for more than the first criterion number of times. Here, the first criterion number of times can be appropriately set according to various factors such as the specifications of the battery cell 1 or the operating conditions of the battery system. The first criterion number of times can be preset and stored in the memory unit 400 or the processor 200. As an example, the first criterion number of times can be set to 5 times. In this case, the processor 200 can determine whether the situation where the SOH calculated value B1 is equal to or less than the threshold value A1 continues for 5 times or more.

[0082] As a more specific example, see Figure 4 When time elapses from d1 to d2, processor 200 may identify a portion where the calculated SOH value B1 is less than threshold A1. In this case, processor 200 may extract portion e1, portion e2, and portion e3 from the portion where the calculated SOH value B1 is less than threshold A1 as continuous portions. Furthermore, processor 200 may determine whether, among the extracted portions, the portion where the calculated SOH value B1 is less than threshold A1 continues for more than a first criterion number of times. For example, when the first criterion number of times is set to 5, processor 200 may identify a portion where the calculated SOH value B1 is less than threshold A1 continues for 5 or more times.

[0083] exist Figure 4 In section e1, the calculated SOH value B1 is less than threshold A1 only once, while in section e2, the calculated SOH value B1 is less than threshold A1 only twice. Therefore, when section e1 or e2 is identified, processor 200 may not determine that an electrode tab defect has occurred in battery cell 1. However, in section e3, the calculated SOH value B1 is less than threshold A1 five or more times. Therefore, when section e3 is identified, processor 200 may determine that an electrode tab defect has occurred in battery cell 1. Specifically, processor 200 may detect a disconnection defect for the corresponding battery cell 1 starting from the first time point da when section e3 begins. That is, if the calculated SOH value B1 is less than threshold A1 for a predetermined time or longer, processor 200 may determine that an electrode tab disconnection has occurred for the corresponding battery cell 1. Furthermore, if the calculated SOH value B1 is less than threshold A1 for more than a first criterion number of times, processor 200 may determine that the capacity of the corresponding battery cell 1 has degraded. In addition, the processor 200 may send the capacity degradation determination result to the user through the notification unit 300 .

[0084] At the same time, Figure 4 In the embodiment described above, a disconnection defect or capacity degradation of a battery cell 1 is detected based on the number of times the calculated SOH value B1 is equal to or less than the threshold value A1. However, a disconnection defect of a battery cell 1 may also be detected based on the time when the calculated SOH value B1 is equal to or less than the threshold value A1. For example, if the calculated SOH value B1 of a particular battery cell 1 is less than or equal to the threshold value A1 for a certain number of days (e.g., 4 days), the processor 200 may be configured to detect a disconnection defect for the corresponding battery cell 1.

[0085] Meanwhile, even if the number of times that the SOH calculation value B1 is equal to or less than the threshold value A1 is determined to be greater than or equal to the first criterion number, if the SOH B1 calculated within a predetermined time thereafter is determined to be greater than the threshold value A1, the processor 200 may cancel the determination of the disconnection defect detected for the corresponding battery cell 1. Figure 4 After section e3 of the embodiment, if the SOH calculation value B1 is equal to or greater than threshold value A1 for more than a predetermined number of times, the processor 200 may cancel the disconnection defect determination made at time point e3. In this case, the disconnection defect can be determined more accurately.

[0086] In addition, if a disconnection defect is judged by the processor 200, various additional information can be obtained depending on the defect judgment time point. For example, in the case where the monomer is judged to have a disconnection defect in the initial stage when the monomer is installed in the battery system, if the monomer is in the BOL (beginning of life) state, that is, if the monomer is in the state just after manufacturing, it can be judged that there is a problem during the manufacturing process of the corresponding monomer. Therefore, in this case, information related to the manufacturing process of the corresponding monomer can be sent to help solve the problem in the manufacturing process of the corresponding monomer. If the corresponding monomer is a monomer in the MOL (middle of life) state, that is, if the monomer is in a state of being used to a certain extent, information about the problem can be obtained by tracking the existing usage history, etc. Alternatively, if the monomer is judged to have a disconnection defect in a state of being used to a certain extent after being installed in the battery system, problems with the operating system or operating conditions or problems at the manufacturing time point can be additionally and comprehensively reviewed.

[0087] In addition, the processor 200 may be configured to determine whether the number of up / down switching of the SOH calculation value relative to the threshold value continues to exceed the second criterion number. In addition, the processor 200 may be configured to detect an incomplete contact defect with respect to the corresponding battery cell 1 when the number of up / down switching continues to exceed the second criterion number. Figure 5 This is described in more detail.

[0088] Figure 5 is a graph showing the SOH calculated by the processor 200 for another battery cell 1 together with a threshold value to be compared therewith according to an embodiment of the present disclosure.

[0089] refer to Figure 5 , indicating that during the period from d1 to d2, Figure 4 A graph of SOH calculated for another battery cell 1 different from the battery cell 1 is illustrated as B2. In addition, in the graph B2, the SOH value calculated at each time point is shown as a point, and such points are connected by a line. In addition, Figure 5 The threshold value is Figure 4 The thresholds are shown in the same way.

[0090] In this embodiment, when the calculated SOH B2 is compared with the threshold value A1, the processor 200 may identify a portion that is greater than or equal to the threshold value A1 and is switched to be less than the threshold value A1. That is, the processor 200 may count the number of times or time periods when the calculated SOH value B2 rises after being less than the threshold value A1 or when the calculated SOH value B2 decreases after being higher than the threshold value A1.

[0091] For example, the processor 200 may Figure 5The switching point of the SOH calculation value B2 relative to the threshold value A1 is identified in the configuration. In addition, the processor 200 can determine whether the number of consecutive switching points is equal to or greater than the second criterion number. Here, the second criterion number can be appropriately set according to various circumstances such as the specifications of the battery cell 1 or the operating conditions of the battery system. In addition, the second criterion number can be preset and stored in the memory unit 400 or the processor 200. For example, the second criterion number can be set to 3 times. In this case, when the number of switching times of the SOH calculation value B2 relative to the threshold value A1 continues for 3 times or more, the processor 200 can determine that there is an incomplete contact defect in the electrode terminal tab of the corresponding battery cell 1.

[0092] As a more specific example, see Figure 5 , when time elapses from d1 to d2, the processor 200 may identify f1, f2, f3, ..., f11 as time points at which the SOH calculation value B2 is switched in the vertical direction based on the threshold value A1. In particular, the vertical direction switching time point may be a point at which the curve graph of the SOH calculation value B2 and the curve graph of the threshold value A1 intersect each other. In addition, the processor 200 may determine whether each switching time point continues for more than the second criterion number of times, for example, three or more times. Here, the continuity of the switching time point may be considered to mean that the switching portion relative to the threshold value occurs continuously between the operating time points at three or more SOH calculation time points.

[0093] exist Figure 5 In the embodiment, at time points f1, f2, and f3, the switching times are not considered continuous, but rather a single switching event. Furthermore, at f4 and f5, since two switching events occur at three consecutive SOH calculation time points, the number of consecutive switching events can be considered to correspond to two. Because the number of consecutive switching events is less than three, which serves as the second criterion, processor 200 may not determine that battery cell 1 has an incomplete contact defect at time points f1 through f5.

[0094] However, the SOH threshold switches continuously from time point f6 to time point f11. That is, from time point f6, the number of switching times of the SOH calculation value relative to the threshold continues up to 6 times, and can be considered to continue to exceed the second criterion number (3 times). Therefore, in this case, the processor 200 can determine that an incomplete contact defect occurs in the electrode terminal tab of the battery cell 1. The incomplete contact defect can be considered as a situation where one electrode terminal tab inside the battery cell 1 is repeatedly attached to another electrode terminal tab or electrode lead and then separated from it. If the SOH calculation value B2 vibrates up and down continuously based on the threshold value A1 as above, the processor 200 can determine that an incomplete contact defect occurs in the electrode terminal tab of the corresponding battery cell 1. In addition, if the SOH calculation value B2 vibrates up and down continuously based on the threshold value A1, the processor 200 can determine that the capacity of the corresponding battery cell 1 is unstable. In addition, the processor 200 can send this information to the user through the notification unit 300.

[0095] According to this embodiment, it is possible to effectively identify whether there is an incomplete contact defect in the electrode tab of the battery cell 1 by comparing the SOH calculation value B2 with the threshold value A1.

[0096] At the same time, Figure 5 In the embodiment of FIG, a configuration for identifying whether there is an incomplete contact defect in the electrode tab of the battery cell 1 by comparing the SOH calculated value B2 of each battery cell 1 with the threshold value A1 is described, but the incomplete contact defect of the electrode tab can also be identified only by the SOH calculated value. Figure 6 This is described in more detail.

[0097] Figure 6 is a graph showing the SOH calculated for yet another battery cell 1 by the processor 200 according to an embodiment of the present disclosure.

[0098] refer to Figure 6 , a graph indicating the SOH calculated for any one battery cell 1 during the period from d3 to d4 is illustrated as B3. Here, too, the SOH value calculated at each time point is indicated by a point, and such points are connected by a line. However, unlike in Figure 4 and Figure 5 Different in Figure 6 The threshold is not shown.

[0099] The processor 200 may calculate the SOH variation between each calculation with respect to the SOH calculation result graph. Here, the SOH variation may mean the difference between consecutive SOH calculation values. In addition, the processor 200 may be configured to compare the calculated SOH variation with the SOH value calculated by the SOH calculation result graph. Figure 6Next, if the SOH variation is greater than the criterion variation Mt for more than a predetermined number of times, such as a third criterion number of times, the processor 200 may be configured to detect that the corresponding battery cell 1 has an incomplete contact defect.

[0100] More specifically, in Figure 6 In the configuration, sections g1 to g7 indicate where the SOH variation exceeds the criterion variation Mt. In sections g1 and g2, the number of consecutive occurrences is two. Furthermore, in sections g3 to g7, the number of consecutive occurrences is five. If the third criterion number is three, the processor 200 may determine that an incomplete contact defect has occurred in the electrode tab of the corresponding battery cell 1 at time points g3 to g7, where the SOH variation exceeds the criterion variation Mt three or more times in a row.

[0101] In the above embodiment, the processor 200 may be configured to regard the immediately preceding pattern as the number of times the SOH change amount is greater than the criterion change amount Mt. More specifically, if the SOH change amount increases or decreases in the same pattern as the preceding pattern, the processor 200 may not count the number of times the SOH change amount is greater than the criterion change amount Mt even if the SOH change amount is greater than the criterion change amount Mt. That is, the processor 200 may count the number of times the SOH change amount is greater than the criterion change amount Mt only when the SOH change amount increases or decreases in a pattern different from the preceding pattern. For example, if the SOH change amount increases in the calculation results of the previous number of times and the SOH change amount decreases in the calculation results of the current number of times, or if the SOH change amount decreases in the calculation results of the previous number of times and the SOH change amount increases in the calculation results of the current number of times, the processor 200 may be configured to determine whether the SOH change amount is greater than the criterion change amount Mt. In this case, in the form of the SOH calculation value vibrating up and down, the processor 200 can count the number of times when the amplitude of the vibration is equal to or greater than a certain level (criterion change amount) and detect the incomplete contact defect of the corresponding battery cell 1 based on the counting result.

[0102] According to this configuration of the present disclosure, even if a threshold value to be compared with SOH is not set, an electrode tab defect of the battery cell 1, particularly whether there is an incomplete contact defect, can be detected. Therefore, a process for storing or calculating a threshold value may not be necessary.

[0103] In addition, the processor 200 may be configured to identify whether the number of times the SOH calculated value switches upward / downward relative to the threshold value increases or decreases. That is, the processor 200 may count the number of times the SOH calculated value switches from upward to downward or from downward to upward based on the threshold value. In addition, the processor 200 may record the counting result each time and identify whether the number of switches gradually increases or decreases over time.

[0104] In particular, if the number of switching times gradually increases over time, the processor 200 may determine that there is a high risk of a problem occurring in the electrode tab. In addition, if the number of switching times increases over time, the processor 200 may determine that the electrode tab of the corresponding battery cell 1 is progressing from a normal state to an incomplete contact defect state or from an incomplete contact defect state to a disconnection defect state.

[0105] The threshold value may be set based on the SOH of at least some of the plurality of battery cells 1. In addition, the processor 200 may set the threshold value based on the SOH values ​​calculated for at least some of the battery cells 1, in particular, all of the battery cells 1, among all the battery cells 1 included in the battery system. Figure 7 This is described in more detail.

[0106] Figure 7 is a graph showing calculated SOH values ​​of several battery cells 1 included in the battery system according to an embodiment of the present disclosure.

[0107] refer to Figure 7 , SOH is calculated for each of the plurality of battery cells 1, and SOH is calculated multiple times over time. In addition, the SOH value calculated for each battery cell 1 is displayed each time. Figure 7 In FIG. 1 , the x-axis represents time based on days, and the y-axis represents SOH calculation values ​​in the form of standard deviations. In addition, in the y-axis, with the average value of all SOH calculation values ​​at the center, the deviation based on the center is shown as σ (sigma). In particular, Figure 7 , S1 and S2 represent limits corresponding to 3σ. As the standard deviation of the mean, the processor 200 may set the value corresponding to 3σ as the threshold value for each time (number of calculations). In addition, the processor 200 may detect electrode tab defects of each battery cell 1 by comparing the value corresponding to 3σ, i.e., the threshold value, with the calculated SOH value of each battery cell 1. In particular, the processor 200 may set the lower limit values ​​of the two values ​​corresponding to 3σ located on both sides of the mean value, i.e., the threshold value S1 corresponding to +3σ and the threshold value S2 corresponding to -3σ, as the threshold value.

[0108] According to this configuration of the present disclosure, it is possible to effectively diagnose problems in a specific battery cell 1, particularly whether there is a defect in the electrode tab, taking into account the overall situation of the battery system. Furthermore, the SOH of a battery cell 1 included in the battery system may vary depending on various factors, such as the operating state of the battery system or the surrounding environment. According to this embodiment, since the threshold value is appropriately set based on these factors, it is possible to more accurately diagnose an electrode tab defect problem in a specific battery cell 1. Furthermore, according to this embodiment, it is not necessary to pre-store the threshold value in the memory unit 400, the processor 200, or the like.

[0109] At the same time, Figure 7 , a value corresponding to 3σ is illustrated as a threshold value, but this is merely an example, and the threshold value may be set to another value such as 6σ. That is, the processor 200 may be configured to compare a value corresponding to 6σ relative to the average value of all battery cells 1 as a threshold value with the SOH of each battery cell 1. Alternatively, the processor 200 may diagnose whether the SOH of each battery cell 1 is abnormal based on a cell-to-cell level variation in the SOH value of each battery cell 1, or based on a difference between the SOH value of each battery cell 1 and the average SOH value of the entire battery system. In addition, the processor 200 may evaluate the calculated SOH value of each battery cell 1 in various other forms, and may determine whether the electrode tab of the corresponding battery cell 1 has a defect.

[0110] When calculating the SOH for each of the plurality of battery cells 1, the processor 200 may be configured so that the criterion time points for calculating the SOH between the battery cells 1 may be the same or have only a time error within a predetermined level. Here, since the SOH calculation is based on the results measured by the cell measurement unit 100, the cell measurement unit 100 may be configured so that the voltage measurement time point or the current measurement time point for each of the plurality of battery cells 1 is made at the same or similar time period. For example, when a plurality of battery cells 1 are included in the battery system, the cell measurement unit 100 may be configured to measure the voltage or current of all battery cells 1 simultaneously or within a time error range of less than 1 second during each measurement cycle.

[0111] According to this configuration of the present disclosure, reliability of threshold setting is ensured by allowing the criterion time points for SOH calculation of the battery cells 1 to be the same or within a certain level, and accuracy of diagnosis can be improved by comparison between the threshold and the calculated value.

[0112] In addition, when a defective battery cell is detected, the processor 200 may be configured to separately perform a charging process and a discharging process for each battery cell 1 .

[0113] For example, the processor 200 may be configured to separately identify the SOH mode calculated based on the voltage measured during charging and the SOH mode calculated based on the voltage measured during discharging. In this case, the thresholds may be set separately for the charging threshold and the discharging threshold. For example, the SOH mode may be set separately. Figure 7 Thresholds are shown in the form of 3σ to correspond to the charge state and discharge state, respectively.

[0114] In addition, the processor 200 may be configured to compare, for each battery cell 1 , the calculated SOH value during discharge with a discharge threshold, and to compare the calculated SOH value during charge with a charge threshold.

[0115] According to this configuration of the present disclosure, since the charging process and the discharging process are compared separately, the state of the battery cell 1 can be diagnosed more accurately. In particular, the state of health (SOH) pattern of the battery cell 1 can be formed differently depending on whether it is in a charging state or a discharging state, and according to this embodiment, the SOH can be diagnosed by more appropriately reflecting this situation. Therefore, the accuracy of diagnosing electrode tab defects of the battery cell 1 can be further improved.

[0116] In particular, the processor 200 may set a precondition for calculating the SOH for the battery cell 1. That is, the processor 200 may be configured to calculate the SOH only when the predetermined precondition is satisfied. Alternatively, the processor 200 may be configured not to calculate the SOH when the precondition is not satisfied.

[0117] For example, the processor 200 may use the SOC to calculate the SOH. Here, the method of obtaining the SOC is well known at the filing date of this application, and thus will not be described in detail here.

[0118] More specifically, the processor 200 may be configured to calculate the SOH through Equation 1 below.

[0119] [Equation 1]

[0120]

[0121] Here, I means current flowing in the battery cell 1, f means charge / discharge end time, and i means charge / discharge start time. In addition, SOCf means the SOC value at the end of charge / discharge, and SOCi means the SOC value at the start of charge / discharge.

[0122] Here, the processor 200 may use the SOC change during the charging / discharging process as a prerequisite for calculating the SOH. In particular, the processor 200 may be configured to calculate the SOH of each battery cell 1 only when the difference between the SOC value at the start of charging and discharging and the SOC value at the end of charging and discharging of each battery cell 1 is equal to or greater than a certain level.

[0123] For example, in Equation 1, regarding the absolute value of the difference between the SOC value at the start of charging and discharging and the SOC value at the end of charging and discharging, the processor 200 may be configured to calculate the SOH only when |(SOCf-SOCi)|≥50. In this case, it can be considered that the SOH is calculated only when the charging or discharging process is 50% or more.

[0124] According to this configuration of the present disclosure, SOH can be calculated only when charging or discharging is sufficiently performed above a certain level. In this case, the accuracy and reliability of SOH calculation can be further improved.

[0125] In addition, the processor 200 may use the time difference between the start time and the end time of the charge / discharge process as a prerequisite for calculating the SOH. In particular, the processor 200 may be configured to calculate the SOH of each battery cell 1 only when the time difference between the charge / discharge end time and the charge / discharge start time of the corresponding battery cell 1 is equal to or greater than a certain level.

[0126] For example, in Equation 1, the processor 200 may be configured to calculate the SOH only when (fi)≧3600s. In this case, the SOH may be calculated only when the charging or discharging process lasts for 3600 seconds or longer.

[0127] According to this configuration of the present disclosure, since the SOH is calculated only when charging or discharging continues for a predetermined time or longer, the accuracy and reliability of the SOH calculation can be further improved.

[0128] Furthermore, the processor 200 may be configured to calculate the SOH when both of the above-mentioned two preconditions, ie, the precondition for the difference between the SOCs and the precondition for the time difference, are satisfied.

[0129] In the above embodiment, the processor 200 may be configured to differently set the preconditions for the charging process and the preconditions for the discharging process.

[0130] For example, as a precondition during the charging process, the processor 200 may be configured to calculate SOH when the SOC is less than or equal to a certain level at the start of charging. That is, the processor 200 may be configured not to calculate SOH when the SOC at the start of charging exceeds a predetermined level.

[0131] As a more specific example, processor 200 may be configured to calculate SOH when battery cell 1 satisfies SOCi ≤ 7 in Equation 1 during the charging process. Here, processor 200 may not calculate SOH when SOCi, which is the SOC at the start of charging, exceeds 7%. According to this embodiment, the problem of deterioration in the accuracy of SOH calculation during charging due to charging being performed only in an excessively high SOC interval can be prevented. At the same time, in this embodiment, 7%, which is the upper limit of SOCi, can be set differently depending on the specifications of battery cell 1 or the operating method of the battery system.

[0132] As another example, as a precondition during the discharge process, the processor 200 may be configured to calculate SOH when the SOC is greater than or equal to a certain level at the start of discharge. That is, the processor 200 may be configured not to calculate SOH when the SOC at the start of discharge is less than a certain level.

[0133] As a more specific example, during the discharge process, the processor 200 may be configured to calculate the SOH when SOCi ≥ 50 in Equation 1. Here, if the SOCi, which is the SOC at the start of discharge, is less than 50%, the processor 200 may not calculate the SOH. According to this embodiment, the problem of deterioration in the accuracy of the SOH calculation during discharge due to discharge in an excessively low SOC interval can be prevented. At the same time, in this embodiment, 50%, which is the lower limit of the SOCi, can be set differently depending on the specifications of the battery cell 1 or the operating method of the battery system.

[0134] According to this configuration of the present disclosure, the SOH is calculated separately for the charging process and the discharging process. In particular, the prerequisites for calculating the SOH can be set differently for the charging process and the discharging process. In this case, the SOH can be calculated under the most appropriate conditions depending on whether the battery cell 1 is charging or discharging. As a result, the accuracy and reliability of the SOH calculation can be further improved.

[0135] Furthermore, an upper limit condition for the charge start SOC or a lower limit condition for the discharge start SOC may be set as a precondition for SOH calculation along with the other common conditions described above. For example, during charging, the processor 200 may be configured to calculate the SOH during charging only when both the upper limit condition for the charge start SOC (SOCi) and the condition that the absolute value of the SOC difference (|SOCf - SOCi|) is equal to or greater than a certain level and the condition that the charge time (fi) is equal to or greater than a certain level are satisfied. Furthermore, during discharging, the processor 200 may be configured to calculate the SOH during discharging only when both the lower limit condition for the discharge start SOC (SOCi) and the condition that the absolute value of the SOC difference (|SOCf - SOCi|) is equal to or greater than a certain level and the condition that the discharge time (fi) is equal to or greater than a certain level are satisfied.

[0136] According to this configuration of the present disclosure, during charging or discharging, by allowing the SOH to be calculated only in a case where a more accurate SOH can be obtained, the accuracy of the SOH calculation can be further improved.

[0137] The battery system according to the present disclosure may include the battery system diagnostic device according to the present disclosure. Here, the battery system may include various types of systems, such as battery modules, battery packs, battery racks, battery banks, and energy storage systems (ESS). That is, the battery system according to the present disclosure may be implemented in the form of a battery module having a plurality of battery cells 1 inside a module housing, or may be implemented in the form of a battery pack having a plurality of battery modules. In addition, the battery system according to the present disclosure may be implemented in the form of a battery rack having a rack frame configured to stack a plurality of battery modules or battery packs and a plurality of battery modules or battery packs accommodated in the rack frame. Alternatively, the battery system according to the present disclosure may be implemented in the form of a battery bank including a plurality of battery racks. Alternatively, the battery system according to the present disclosure may be implemented in the form of an energy storage system including a plurality of battery banks.

[0138] Figure 8 FIG. 1 is a flow chart for schematically illustrating a battery system diagnosis method according to an embodiment of the present disclosure. Figure 8 In the embodiment of the present invention, each step can be performed by each component of the above-mentioned battery system diagnostic device.

[0139] refer to Figure 8 The battery system diagnosis method according to the present disclosure is a method of diagnosing a battery system including a plurality of battery cells 1 having electrode tabs therein, and may include a measuring step (S110), a calculating step (S120), and a detecting step (S130).

[0140] Here, step S110 may be a step of measuring voltage or current for each of the plurality of battery cells 1 included in the battery system.

[0141] Next, step S120 may be a step of calculating the SOH for each battery cell 1 a plurality of times over time by using the voltage or current measured in step S110 .

[0142] In addition, step S130 may be a step of detecting a battery cell having a defect in an electrode tab among the plurality of battery cells 1 based on the SOH of each battery cell 1 calculated a plurality of times in step S120 .

[0143] With respect to the details of the battery system diagnosis method according to the present disclosure, the features of the battery system diagnosis apparatus according to the present disclosure described above may be applied in the same or similar manner, and thus they will not be described in detail.

[0144] The present disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present disclosure, are given by way of illustration only, as various changes and modifications within the scope of the present disclosure will become apparent to those skilled in the art from this detailed description.

[0145] Reference numerals

[0146] 1: Battery cell

[0147] 10: Electrode terminal

[0148] 11: positive terminal lug, 12: negative terminal lug

[0149] 20: Electrode assembly

[0150] 30: Bag exterior

[0151] 31: upper bag, 32: lower bag

[0152] 41: positive lead, 42: negative lead

[0153] 100: Single measurement unit

[0154] 200: Processor

[0155] 300: Notification unit

[0156] 400: Memory unit

Claims

1. A battery system diagnostic device for diagnosing a battery system comprising a plurality of battery cells, wherein the battery cells have electrode tabs, the device comprising: a cell measuring unit configured to measure a voltage or a current for each of the plurality of battery cells; as well as a processor configured to calculate the SOH for each battery cell a plurality of times over time by using the voltage or current measured by the cell measurement unit, and detect a battery cell having a defect in the electrode tab among the plurality of battery cells based on the SOH of each battery cell calculated a plurality of times, When the calculated SOH value is equal to or less than a threshold value for a number of times exceeding a first criterion, the processor is configured to detect that the corresponding battery cell has a disconnection defect.

2. The battery system diagnostic device according to claim 1, in, When the number of times the SOH calculation value switches upward / downward relative to the threshold value continuously exceeds a second criterion number, the processor is configured to detect that the corresponding battery cell has an incomplete contact defect.

3. The battery system diagnostic device according to claim 2, in, The processor is configured to identify whether the number of up / down switches is increasing or decreasing.

4. The battery system diagnostic device according to claim 1, in, The threshold value is set based on the SOH of at least some of the plurality of battery cells.

5. The battery system diagnostic device according to claim 1, in, The processor is configured to detect a defective battery cell by distinguishing a charging process from a discharging process for each battery cell.

6. The battery system diagnostic device according to claim 5, in, The processor is configured to set a precondition for calculating the SOH for each battery cell such that a precondition for the charging process and a precondition for the discharging process are set differently from each other. 7 . A battery system comprising the battery system diagnostic device according to claim 1 .

8. A battery system diagnostic method, the battery system diagnostic method diagnosing a battery system including a plurality of battery cells, wherein the battery cells have electrode tabs, the method comprising: measuring a voltage or a current for each of the plurality of battery cells; calculating the SOH for each battery cell a plurality of times over time by using the voltage or current measured in the measuring step; as well as detecting a battery cell having a defect in the electrode tab among the plurality of battery cells based on the SOH of each battery cell calculated a plurality of times in the calculating step, When the SOH is equal to or less than the threshold value for a continuous period exceeding a first criterion number of times, it is detected that the corresponding battery cell has a disconnection defect.

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