Method and apparatus for diagnosing internal short circuit in battery

Abstract

A method and apparatus for diagnosing an internal short circuit in a battery cell are provided. The method includes: measuring charge / discharge efficiency of a battery cell in each of a plurality of charge / discharge cycles; measuring a temperature of the battery cell in each of the plurality of charge / discharge cycles; calculating a change in charge / discharge efficiency of the charge / discharge cycle with respect to a previous charge / discharge cycle in each of the plurality of charge / discharge cycles; calculating, in each of the plurality of charge / discharge cycles, a change in the charge / discharge cycle with respect to a temperature in a previous charge / discharge cycle; and diagnosing an internal short circuit of the battery cell on the basis of the change in charge / discharge efficiency and the change in temperature.

Description

[0001] This application claims priority and benefit to Korean Patent Application No. 10-2024-0082114, filed on June 24, 2024, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to a method and apparatus for diagnosing internal short circuits in a battery. Background Technology

[0003] Small-sized lithium-ion rechargeable batteries are increasingly used in devices such as mobile phones and laptops. Recently, there has also been an increasing demand for high-capacity rechargeable batteries with the long lifespan, high output characteristics, and safety desired for applications requiring high capacity.

[0004] Lithium-ion rechargeable batteries can be manufactured by using anode and cathode materials that absorb and release lithium ions; installing a separator between the anode and cathode; and providing an electrolyte. Lithium ions move between the anode and cathode via the electrolyte, thereby allowing the battery to charge and discharge.

[0005] A secondary battery (i.e., a battery cell) may include an electrode assembly, a housing containing the electrode assembly, and electrode terminals electrically connected to the electrode assembly. The electrode assembly includes an anode, a cathode, and a separator inserted between the cathode and the anode. Charging and discharging of the battery cell can be performed by providing an electrolyte within the battery cell's housing and inducing an electrochemical reaction between the anode, cathode, and electrolyte. Depending on the application of the battery cell, the housing may be formed in various shapes, such as cylindrical or rectangular.

[0006] Internal short circuits can occur within a single battery cell, causing a short circuit between the anode and cathode due to loss of separator function. These internal short circuits can be attributed to factors such as deformation caused by external impacts, the introduction of metallic foreign matter during manufacturing, or the formation of lithium or copper dendrites due to electrochemical reactions. Internal short circuits within a single battery cell can lead to safety issues such as thermal runaway.

[0007] Furthermore, in secondary batteries used in high-capacity systems such as electric vehicles or energy storage systems (ESS), long lifespan, high output characteristics, and safety are desirable due to the characteristics of high-capacity systems. However, when batteries are contaminated with scrap-type foreign matter, including abnormal metallic foreign objects or substrates, lithium salts may grow around the foreign matter region and penetrate the separator under pressure conditions where the cell swelling is restricted by the external separator wall. This leads to the risk of thermal runaway due to internal short circuits in the battery cells. Summary of the Invention

[0008] At least one embodiment provides a method and apparatus for diagnosing internal short circuits in a battery, which can pre-diagnose internal short circuits in a lithium secondary battery.

[0009] According to an embodiment, a method for diagnosing internal short circuits in a single battery cell can be provided. The method includes: measuring the charge / discharge efficiency of the battery cell in each of a plurality of charge / discharge cycles; measuring the temperature of the battery cell in each charge / discharge cycle; calculating the change in charge / discharge efficiency relative to the previous charge / discharge cycle in each charge / discharge cycle; calculating the change in temperature relative to the previous charge / discharge cycle in each charge / discharge cycle; and diagnosing the internal short circuit in the battery cell based on the changes in charge / discharge efficiency and temperature.

[0010] The steps for diagnosing an internal short circuit in a battery cell may include: counting the number of anomalies if the change in charge / discharge efficiency therein is greater than or equal to a first threshold and the change in temperature in a first charge / discharge cycle is greater than or equal to a second threshold; and determining an internal short circuit in the battery cell if the number of anomalies is greater than a reference number.

[0011] The steps for diagnosing an internal short circuit in a battery cell may include: determining an internal short circuit in the battery cell if the change in charge / discharge efficiency compared to the previous charge / discharge cycle is greater than or equal to a first threshold and the change in temperature compared to the previous charge / discharge cycle is greater than or equal to a second threshold.

[0012] The steps for measuring the charge / discharge efficiency of a single battery cell may include: measuring the charge capacity of the battery cell during the charging period in each charge / discharge cycle; measuring the discharge capacity of the battery cell during the discharging period in each charge / discharge cycle; and calculating the charge / discharge efficiency using the charge capacity and discharge capacity of the battery cell in each charge / discharge cycle.

[0013] According to another embodiment, an apparatus for diagnosing internal short circuits in a battery cell can be provided. The apparatus for diagnosing internal short circuits in a battery cell includes: a charging / discharging device configured to charge the battery cell during a charging period of each of a plurality of charge / discharge cycles and to discharge the battery cell during a discharging period of each charge / discharge cycle; a measuring device configured to measure the charging capacity of the battery cell during the charging period of each charge / discharge cycle and the discharging capacity of the battery cell during the discharging period of each charge / discharge cycle, and to measure the temperature of the battery cell during each charge / discharge cycle; and a controller configured to: (i) generate, for each charge / discharge cycle, a first curve representing a change in charge / discharge efficiency compared to a previous charge / discharge cycle and a second curve representing a change in temperature compared to a previous charge / discharge cycle; and (ii) diagnose internal short circuits in the battery cell based on the first curve and the second curve.

[0014] The controller can also be configured to determine an internal short circuit in a battery cell if the change in charge / discharge efficiency compared to the previous charge / discharge cycle is greater than or equal to a first threshold and the change in temperature compared to the previous charge / discharge cycle is greater than or equal to a second threshold.

[0015] The first threshold can be set as a standard for determining the increase in charge / discharge efficiency, and the second threshold can be set as a standard for determining the increase in temperature.

[0016] The controller can also be configured to determine an internal short circuit in a battery cell if the number of times the change in charge / discharge efficiency compared to the previous charge / discharge cycle is greater than or equal to a first threshold and the number of times the change in temperature compared to the previous charge / discharge cycle is greater than or equal to a second threshold is greater than or equal to a reference number.

[0017] The controller can also be configured to discharge a battery cell when an internal short circuit is detected in the battery cell.

[0018] According to another embodiment, a method for diagnosing internal short circuits in a battery cell can be provided, wherein the method includes: measuring the charge / discharge efficiency and temperature of the battery cell in a first charge / discharge cycle; measuring the charge / discharge efficiency and temperature of the battery cell in a second charge / discharge cycle following the first charge / discharge cycle; increasing the number of anomalies if the change in charge / discharge efficiency of the battery cell between the first and second charge / discharge cycles is greater than or equal to a first threshold, and the change in temperature of the battery cell between the first and second charge / discharge cycles is greater than or equal to a second threshold; and determining whether an internal short circuit exists in the battery cell based on the number of anomalies.

[0019] The steps to determine whether an internal short circuit exists in a battery cell may include: if the number of abnormalities reaches a reference number, then it is determined that an internal short circuit has occurred in the battery cell.

[0020] The method for diagnosing internal short circuits in a battery cell may further include: measuring the charge / discharge efficiency and temperature of the battery cell in a third charge / discharge cycle; measuring the charge / discharge efficiency and temperature of the battery cell in a fourth charge / discharge cycle following the third charge / discharge cycle; and increasing the number of anomalies if the change in charge / discharge efficiency of the battery cell between the third and fourth charge / discharge cycles is greater than or equal to a first threshold, and the change in temperature of the battery cell between the third and fourth charge / discharge cycles is greater than or equal to a second threshold. Attached Figure Description

[0021] Figure 1 An apparatus for diagnosing internal short circuits in a battery, according to an embodiment, is shown.

[0022] Figure 2 The charging and discharging capacities of a battery cell for each charge / discharge cycle are shown.

[0023] Figure 3 The temperature of the battery cell for each charge / discharge cycle is shown.

[0024] Figure 4 This is a flowchart illustrating a method for diagnosing internal short circuits in a battery cell according to an embodiment.

[0025] Figure 5 This is a flowchart illustrating a method for diagnosing an internal short circuit in a battery cell according to another embodiment.

[0026] Figure 6 An apparatus for diagnosing internal short circuits in a battery, according to another embodiment, is shown. Detailed Implementation

[0027] Exemplary embodiments will now be described more fully below with reference to the accompanying drawings. However, this disclosure may be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementation methods to those skilled in the art. The drawings and description are to be considered illustrative rather than restrictive in nature. Throughout the specification, the same reference numerals denote the same elements. In the flowcharts described herein with reference to the accompanying drawings, the order of operations may be changed, several operations may be combined, some operations may be divided, and certain operations may not be performed.

[0028] Throughout the specification and claims, if a part is referred to as "comprising" a certain element, this may mean, unless otherwise specified, that part may further include other elements without excluding them.

[0029] Furthermore, unless an explicit expression such as "a" or "single" is used, an expression described in the singular can be interpreted as either singular or plural.

[0030] Furthermore, terms including ordinal numbers such as first, second, etc., may be used to describe various elements, but elements are not limited by the terms. Such terms are used only for the purpose of distinguishing one element from another. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0031] Furthermore, if a component is described as being "connected" to another component, this includes cases where the two components are "directly connected," or where the two components are "indirectly or non-contactly connected" by inserting another component between them, or where the two components are "electrically connected." On the other hand, if an element is described as being "directly connected" to another element, it should be understood that there are no other elements in between.

[0032] Figure 1 An apparatus for diagnosing internal short circuits in a battery, according to an embodiment, is shown.

[0033] Reference Figure 1 The device 100 for diagnosing internal short circuits in a battery may include a battery cell 110, a charging / discharging device 120, a measuring device 130, a controller 140, and a storage device 150.

[0034] The battery cell 110 can be manufactured by: fabricating the anode and cathode using anode active materials and cathode active materials capable of absorbing and releasing lithium ions, respectively; installing a separator between the anode and cathode; and then providing an electrolyte. The battery cell 110 can be a cell that has already been fully fabricated in the manufacturing process. The battery cell 110 can be inserted into a cavity.

[0035] The charging / discharging device 120 can charge or discharge the battery cell 110 based on the charging / discharging control signal of the controller 140.

[0036] The measuring device 130 can measure the characteristic values ​​of the battery cell 110 for each charge / discharge cycle based on the measurement control signal from the controller 140. The measuring device 130 can also transmit the characteristic values ​​of the battery cell 110 to the controller 140. Furthermore, the measuring device 130 can measure the temperature of the battery cell 110 for each charge / discharge cycle. For example, the measuring device 130 may include a temperature sensor for measuring the temperature of the battery cell 110 for each charge / discharge cycle. A charge / discharge cycle may include a charging period, a rest period, a discharging period, and a pause period.

[0037] The controller 140 can collect characteristic values ​​and temperature of the battery cell 110 measured for each charge / discharge cycle. The controller 140 can diagnose internal short circuits in the battery cell 110 caused by lithium salt deposition in the battery cell 110 based on the characteristic values ​​and temperature of the battery cell 110 measured for each charge / discharge cycle.

[0038] According to an embodiment, the characteristic values ​​of the battery cell 110 may include the charging capacity and the discharging capacity of the battery cell 110.

[0039] The charging and discharging device 120 can charge the battery cell 110 during the charging period. Furthermore, the charging and discharging device 120 can discharge the battery cell 110 during the discharging period. The rest period can be a period used to stabilize the battery cell 110.

[0040] According to an embodiment, based on the measurement control signal of the controller 140, if the charging period of a charge / discharge cycle ends, the measuring device 130 can measure the charging capacity of the battery cell 110, and if the discharging period of a charge / discharge cycle ends, the measuring device 130 can measure the discharging capacity of the battery cell 110. Furthermore, if the charging period of a charge / discharge cycle ends, the measuring device 130 can measure the temperature of the battery cell 110 via a temperature sensor, and if the discharging period of a charge / discharge cycle ends, the measuring device 130 can measure the temperature of the battery cell 110 via a temperature sensor.

[0041] The measuring device 130 can transmit the charging capacity of the battery cell 110 measured in each charge / discharge cycle and the temperature of the battery cell 110 measured in each charge / discharge cycle. The measuring device 130 can also transmit the discharging capacity of the battery cell 110 measured in each charge / discharge cycle and the temperature of the battery cell 110 measured in each charge / discharge cycle to the controller 140. For example, if a total of 300 charge / discharge cycles are performed, the controller 140 can obtain the charging capacity of the battery cell 110 for each of the 300 cycles, the temperature of the battery cell 110 at the end of charging for each of the 300 cycles, the discharging capacity of the battery cell 110 for each of the 300 cycles, and the temperature of the battery cell 110 at the end of discharging for each of the 300 cycles.

[0042] The controller 140 can store the charging capacity and discharging capacity of the battery cell 110 for each charge / discharge cycle, the temperature of the battery cell 110 at the end of charging for each charge / discharge cycle, and the temperature of the battery cell 110 at the end of discharging for each charge / discharge cycle in the storage device 150.

[0043] The controller 140 can pre-diagnose internal short circuits in battery cells 110 caused by lithium salt deposition based on the charging capacity and discharging capacity of battery cells 110 during a charge / discharge cycle, the temperature of battery cells 110 at the end of charging, and the temperature of battery cells 110 at the end of discharging.

[0044] In the case of a normal battery cell 110, the charge / discharge efficiency (including charging efficiency and / or coulombic efficiency) is expressed as a percentage of discharge capacity to charge capacity. The charge / discharge efficiency gradually increases with cycling and remains above a predetermined benchmark (e.g., 95%) after the initial charge / discharge cycles (e.g., 5 charge / discharge cycles). However, in the case of a battery cell with an anomaly (e.g., internal short circuit), the charge / discharge efficiency may drop below 90%, possibly due to an exothermic reaction caused by irreversible lithium salt deposition, and the cell temperature may rise. Therefore, the controller 140 can calculate the charge / discharge efficiency of the battery cell 110 for each charge / discharge cycle and diagnose internal short circuits based on the charge / discharge efficiency of the battery cell 110 for each charge / discharge cycle and the temperature of the battery cell 110 for each charge / discharge cycle.

[0045] In some embodiments, after the charge / discharge efficiency is maintained at 95% or higher for a predetermined period of time, the controller can calculate the change in charge / discharge efficiency of the battery cell 110 between the current charge / discharge cycle and the previous charge / discharge cycle, as well as the change in temperature of the battery cell 110 between the current charge / discharge cycle and the previous charge / discharge cycle. Therefore, the controller can diagnose internal short circuits in the battery cell 110 based on the calculated changes in charge / discharge efficiency and temperature in each charge / discharge cycle.

[0046] In this disclosure, the temperature change of the battery cell 110 may represent the difference between the temperature measured at the end of charging in the current charge / discharge cycle and the temperature measured at the end of charging in the previous charge / discharge cycle, or it may represent the difference between the temperature measured at the end of discharging in the current charge / discharge cycle and the temperature measured at the end of discharging in the previous charge / discharge cycle.

[0047] Figure 2 It is a graph showing the charging and discharging capacities of a single battery cell during a charge / discharge cycle, and Figure 3 This is a graph showing the temperature of a battery cell during a charge / discharge cycle.

[0048] Under normal conditions of the battery cell 10, a charge / discharge efficiency higher than a predetermined benchmark (e.g., 95%) can be maintained as charge / discharge cycles proceed. However, as charge / discharge cycles continue, if the cathode and anode of the battery cell 10 short-circuit due to irreversible lithium salt deposition, the charging capacity may increase rapidly and the discharging capacity may decrease rapidly compared to the charging and discharging capacities of the previous charge / discharge cycle (e.g., ...). Figure 2 As shown in the diagram (part of 1250 charge / discharge cycles). Therefore, the change in charge / discharge efficiency can decrease rapidly.

[0049] In addition, such as Figure 3 As shown, in the case of normal battery cells 20 and 30, even when a charge / discharge cycle is in progress, the temperature change between the current charge / discharge cycle and the previous charge / discharge cycle will not exceed a set threshold (e.g., 1°C). However, when a battery cell 10 experiences an internal short circuit due to lithium salt deposition, the temperature of the internally short-circuited battery cell 10 rises rapidly. That is, when battery cell 10 short-circuits due to lithium salt deposition, there may be a point where the temperature change of battery cell 110 between the current charge / discharge cycle and the previous charge / discharge cycle exceeds the threshold, and then the increased cell temperature is maintained.

[0050] The controller 140 can set thresholds for the change in charge / discharge efficiency and the change in temperature compared to the previous charge / discharge cycle based on the characteristics of the battery cell 10 due to lithium salt deposition. The controller 140 can also compare the changes in charge / discharge efficiency and temperature compared to the previous charge / discharge cycle with the corresponding thresholds and diagnose internal short circuits in the battery cell 10.

[0051] Figure 4 This is a flowchart illustrating a method for diagnosing internal short circuits in a battery cell according to an embodiment.

[0052] Reference Figure 4 When the charging / discharging cycle begins (S402), the controller 140 can set i=1 and set the number of abnormalities to 0 (S404).

[0053] The controller 140 can obtain the charging capacity and discharging capacity of the battery cell 110 for each charge / discharge cycle, the temperature of the battery cell 110 at the end of charging for each charge / discharge cycle, and the temperature of the battery cell 110 at the end of discharging for each charge / discharge cycle (S406).

[0054] The controller 140 can calculate the changes in charge / discharge efficiency and temperature for each charge / discharge cycle compared to the previous charge / discharge cycle (S408). Furthermore, as the charge / discharge cycle progresses, the controller 140 can calculate the changes in charge / discharge efficiency and temperature for each charge / discharge cycle compared to the previous charge / discharge cycle.

[0055] The controller 140 may perform the following processing after the charge / discharge efficiency has remained above a certain value for a certain period of time. Optionally, the following processing may be performed starting from i=1. This certain value may be set, for example, 95%. If the change in charge / discharge efficiency calculated in the i-th charge / discharge cycle is less than a first threshold, the controller 140 may determine that the battery cell 110 is normal. Here, i may be the charge / discharge cycle in which the charge / discharge efficiency remains above this certain value.

[0056] The controller 140 can compare the change in charge / discharge efficiency of the i-th charge / discharge cycle with a first threshold (S410). If the change in charge / discharge efficiency of the i-th charge / discharge cycle is less than the first threshold, the controller 140 can set i = i + 1 (S412) and check whether i is less than N (S414). Here, N can represent the total number of charge / discharge cycles. Moreover, if i is less than N, the controller 140 can return to step S406.

[0057] Furthermore, if the change in charge / discharge efficiency during the i-th charge / discharge cycle is greater than or equal to a first threshold, the controller 140 may check the temperature change during the i-th charge / discharge cycle. And if the temperature change during the i-th charge / discharge cycle is less than a second threshold (S416), the controller 140 may execute step S412.

[0058] If the temperature change in the i-th charge / discharge cycle is greater than or equal to the second threshold, the controller 140 may increment the anomaly count by 1 (S418) and execute step S412. If i becomes N, the controller 140 may then check whether the anomaly count is greater than or equal to the reference count (S420). At this time, the reference count may be set to, for example, 1 or 2. If the anomaly count is greater than or equal to the reference count, the controller 140 may therefore determine that the battery cell has an internal short circuit (S422). However, if the anomaly count is less than the reference count, the controller 140 may determine that the battery cell is normal (S424).

[0059] exist Figure 4 In this diagram, step S420 is shown as being executed if i becomes N, but optionally, step S420 can be executed after step S418. That is, if the temperature change in the i-th charge / discharge cycle is greater than or equal to the second threshold, the controller 140 may increment the anomaly count by 1 (S418) and check if the anomaly count is greater than or equal to the reference count. At this time, if the anomaly count is less than the reference count, the controller 140 may execute step S412.

[0060] Figure 5 This is a flowchart illustrating a method for diagnosing an internal short circuit in a battery cell according to another embodiment.

[0061] Reference Figure 5 When the charging / discharging cycle begins (S502), the controller 140 can set the number of abnormalities to 0 (S504).

[0062] The controller 140 can obtain the charging capacity and discharging capacity of the battery cell 110 for each charge / discharge cycle, the temperature of the battery cell 110 at the end of charging for each charge / discharge cycle, and the temperature of the battery cell 110 at the end of discharging for each charge / discharge cycle (S506).

[0063] The controller 140 can calculate the changes in charge / discharge efficiency and temperature for each charge / discharge cycle compared to the previous charge / discharge cycle (S508).

[0064] The controller 140 can generate a charge / discharge efficiency variation curve for each charge / discharge cycle, which represents the difference in charge / discharge efficiency of the battery cell 110 compared to the previous charge / discharge cycle (S510).

[0065] The controller 140 can generate a temperature change curve for each charge / discharge cycle, which represents the temperature difference of the battery cell 110 compared to the previous charge / discharge cycle (S512).

[0066] The controller 140 can check the time when the change in charge / discharge efficiency is greater than or equal to a first threshold in the charge / discharge efficiency change curve for each charge / discharge cycle (S514).

[0067] The controller 140 can use the temperature change curve when the change in charge / discharge efficiency is greater than or equal to a first threshold to check the temperature change (S516).

[0068] If the temperature change is greater than or equal to a second threshold when the change in charge / discharge efficiency is greater than or equal to a first threshold (S518), then the controller 140 can count the number of abnormal events (S520). Figure 4 As described in steps S420 to S424, if the number of abnormal counts after a charge / discharge cycle is greater than or equal to a reference number, the controller 140 can determine that the battery cell 110 has an internal short circuit. Conversely, if the number of abnormal counts after a charge / discharge cycle is less than a reference number, the controller 140 can determine that the battery cell 110 is normal.

[0069] In this way, according to an embodiment, an internal short circuit caused by lithium salt deposition in the battery cell 110 can be pre-diagnosed by utilizing the charge / discharge efficiency and temperature characteristics of the battery cell 110. When an internal short circuit in the battery cell 110 is determined, the controller 140 discharges the battery cell 110.

[0070] Figure 6 This is a diagram illustrating a device for diagnosing internal short circuits in a battery according to another embodiment.

[0071] Reference Figure 6 The device 600 for diagnosing internal short circuits in a battery can be a computing device, which implements the method for diagnosing internal short circuits in a battery as described above.

[0072] Device 600 for diagnosing internal short circuits in a battery may include at least one of a processor 610, a memory 620, an input interface device 630, an output interface device 640, and a storage device 650. Each component may be connected to and communicate with each other via a bus 660. Furthermore, each component may be connected via a separate interface or a separate bus centered on the processor 610, rather than the common bus 660.

[0073] The processor 610 can be implemented as various types such as an application processor (AP), a central processing unit (CPU), a graphics processing unit (GPU), etc., and can be any semiconductor device that executes commands stored in the memory 620 or the storage device 650. The processor 610 can execute the reference program by executing program commands stored in at least one of the memory 620 and the storage device 650. Figures 1 to 5 The description describes the battery's internal short-circuit diagnostic function.

[0074] The memory 620 and storage device 650 may include various forms of volatile or non-volatile storage media. For example, the memory 620 may include read-only memory (ROM) 621 and random access memory (RAM) 622. In embodiments, the memory 620 may be located inside or outside the processor 610, and the memory 620 may be connected to the processor 610 in various known ways.

[0075] The input interface device 630 may be configured to provide data to the processor 610. In some embodiments, the input interface device 630 may provide the processor 610 with the charge capacity, discharge capacity, and temperature of the battery cell 110 for each charge / discharge cycle.

[0076] The output interface device 640 can be configured to output data from the processor 610. In some embodiments, the output interface device 640 can output the internal short-circuit diagnostic results of the battery cell 110.

[0077] According to at least one embodiment, an internal short circuit caused by the deposition of lithium salts in a lithium secondary battery can be diagnosed before a problem (such as thermal runaway or fire) occurs in the battery.

[0078] Although embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto and may include various modifications and improvements made by those skilled in the art using the basic concepts of the present disclosure.

[0079] <Description of reference numerals in the attached figures> 100: Equipment used for diagnosing internal short circuits in batteries 110: Battery cell 120: Charging and discharging device 130: Measuring device 140: Controller 150: Storage device.

Claims

1. A method for diagnosing internal short circuits in a single battery cell, the method comprising: The charge / discharge efficiency of individual battery cells is measured in each of the multiple charge / discharge cycles. In each of the plurality of charge / discharge cycles, the temperature of the individual battery cells is measured; In each of the plurality of charge / discharge cycles, the change in the charge / discharge efficiency relative to the previous charge / discharge cycle is calculated. In each of the plurality of charge / discharge cycles, the change in temperature relative to the previous charge / discharge cycle is calculated. as well as Internal short circuits in the battery cells are diagnosed based on changes in charge / discharge efficiency and temperature.

2. The method according to claim 1, wherein, The steps for diagnosing an internal short circuit in the battery cell include: If the temperature change calculated in a first charge / discharge cycle, in which the change in charge / discharge efficiency is greater than or equal to a first threshold, is greater than or equal to a second threshold, then the number of anomalies is counted; and If the number of abnormal occurrences is greater than the baseline number, then the battery cell is determined to be internally short-circuited.

3. The method according to claim 1, wherein, The steps for diagnosing an internal short circuit in the battery cell include: determining that the battery cell has an internal short circuit if the change in charge / discharge efficiency compared to the previous charge / discharge cycle is greater than or equal to a first threshold and the change in temperature compared to the previous charge / discharge cycle is greater than or equal to a second threshold.

4. The method according to claim 1, wherein, The step of measuring the charge-discharge efficiency of the battery cell includes: In each of the plurality of charge / discharge cycles, the charging capacity of the battery cell during the charging period is measured; In each of the plurality of charge / discharge cycles, the discharge capacity of the individual battery cell during the discharge period is measured; and In each of the plurality of charge / discharge cycles, the charge / discharge efficiency is calculated using the charge capacity and the discharge capacity of the battery cell.

5. An apparatus for diagnosing internal short circuits in a single battery cell, the apparatus comprising: A charging / discharging device is configured to charge a battery cell during a charging period of each of a plurality of charging / discharging cycles, and to discharge the battery cell during a discharging period of each of the charging / discharging cycles. The measuring device is configured to: measure the charging capacity of the battery cell during the charging period of each of the plurality of charge / discharge cycles and the discharge capacity of the battery cell during the discharging period of each of the plurality of charge / discharge cycles, and measure the temperature of the battery cell during each of the plurality of charge / discharge cycles; as well as The controller is configured to: (i) generate a first curve representing the change in charge / discharge efficiency compared to the previous charge / discharge cycle and a second curve representing the change in temperature compared to the previous charge / discharge cycle for each of the plurality of charge / discharge cycles; and (ii) diagnose an internal short circuit of the battery cell based on the first curve and the second curve.

6. The device according to claim 5, wherein, The controller is further configured to determine that the battery cell has an internal short circuit if the change in the charge / discharge efficiency compared to the previous charge / discharge cycle is greater than or equal to a first threshold and the change in temperature compared to the previous charge / discharge cycle is greater than or equal to a second threshold.

7. The device according to claim 6, wherein, The first threshold is set as a standard for determining the increase in charge / discharge efficiency, and the second threshold is set as a standard for determining the increase in temperature.

8. The device according to claim 5, wherein, The controller is further configured to determine that the battery cell has an internal short circuit if the number of times the change in the charge / discharge efficiency compared to the previous charge / discharge cycle is greater than or equal to a first threshold and the number of times the change in temperature compared to the previous charge / discharge cycle is greater than or equal to a second threshold is greater than or equal to a reference number.

9. The device according to claim 5, wherein, The controller is also configured to discharge the battery cell when an internal short circuit is detected in the battery cell.

10. A method for diagnosing internal short circuits in a single battery cell, the method comprising: The charge / discharge efficiency and temperature of the battery cells were measured during the first charge / discharge cycle. The charge / discharge efficiency and temperature of the battery cell are measured in a second charge / discharge cycle following the first charge / discharge cycle. If the change in charge / discharge efficiency of the battery cell between the first charge / discharge cycle and the second charge / discharge cycle is greater than or equal to a first threshold, and the change in temperature of the battery cell between the first charge / discharge cycle and the second charge / discharge cycle is greater than or equal to a second threshold, then the number of anomalies is increased. as well as The presence of an internal short circuit in the battery cell is determined based on the number of anomalous events.

11. The method according to claim 10, wherein, The step of determining whether an internal short circuit exists in the battery cell includes: if the number of abnormalities reaches a reference number, then it is determined that an internal short circuit has occurred in the battery cell.

12. The method according to claim 10, further comprising: The charge / discharge efficiency and temperature of the battery cell were measured during the third charge / discharge cycle. The charge / discharge efficiency and temperature of the battery cell are measured in the fourth charge / discharge cycle following the third charge / discharge cycle. as well as If the change in charge / discharge efficiency of the battery cell between the third and fourth charge / discharge cycles is greater than or equal to the first threshold, and the change in temperature of the battery cell between the third and fourth charge / discharge cycles is greater than or equal to the second threshold, then the number of anomalies is increased.

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