Method, device, equipment, system and medium for detecting internal short circuit of battery cell

Abstract

The present application discloses a method, device, equipment, system and medium for detecting internal short circuit of a battery cell. The method for detecting internal short circuit of a battery cell includes: obtaining the self-discharge current of multiple battery cells at a target temperature, the target temperature is less than a first temperature threshold, the self-discharge current is obtained by measuring the steady-state current of the battery cell when the battery cell in the target state is charged at a constant voltage using a target power supply voltage, wherein the target state includes being at a target temperature and being in a target state of charge, the target power supply voltage is determined based on the battery cell voltage of the battery cell in the target state, and the target state of charge is between 20% and 70%; selecting a self-discharge current from multiple self-discharge currents, and determining a current threshold based on at least one selected self-discharge current; and detecting whether the battery cell has an internal short circuit based on the magnitude relationship between the self-discharge current of the battery cell and the current threshold. The above scheme can improve the accuracy of detecting internal short circuit of the battery cell.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a method, device, equipment, system and medium for detecting internal short circuits in battery cells. Background Art

[0002] The internal short circuit of the battery cell will affect the storage and use of the battery cell. For example, the self-discharge caused by the internal short circuit will cause the battery cell to fail during storage due to low voltage, zero voltage, etc. The internal short circuit may cause poor self-discharge consistency among a batch of battery cells in the battery pack, leading to safety problems such as overcharging and over-discharging, ultimately reducing the life of the battery module or causing safety problems.

[0003] The current detection method for internal short circuit of battery cells cannot accurately detect whether there is an internal short circuit in the battery cell. For example, a battery cell with an internal short circuit may be mistakenly judged as a battery cell without a short circuit. Summary of the invention

[0004] The present application at least provides a method, device, equipment, system and medium for detecting internal short circuit of a battery cell.

[0005] The present application provides a method for detecting an internal short circuit of a battery cell, comprising: obtaining self-discharge currents of a plurality of battery cells at a target temperature, wherein the target temperature is less than a first temperature threshold, and the self-discharge current is obtained by measuring a steady-state current of a battery cell when a target power supply voltage is used to perform constant voltage charging on a battery cell in a target state, wherein the target state includes being at a target temperature and being in a target state of charge, and the target power supply voltage is determined based on the battery cell voltage of the battery cell in the target state, and the target state of charge is between 20% and 70%; selecting a self-discharge current that meets a preset condition from the self-discharge currents of the plurality of battery cells; determining a current threshold based on at least one selected self-discharge current; and detecting whether each battery cell has an internal short circuit based on the magnitude relationship between the self-discharge current of each battery cell and the current threshold.

[0006] In the above scheme, the self-discharge current of multiple battery cells at a target temperature is obtained, the target temperature is less than a first temperature threshold, and the steady-state current is measured at the target temperature to obtain the self-discharge current, which can reduce the chemical self-discharge current of the battery cell and its fluctuation, increase the physical self-discharge current, and expand the difference in self-discharge current between internally short-circuited batteries and non-short-circuited batteries. A threshold is determined based on at least one self-discharge current measured to distinguish whether the battery cell has an internal short circuit, which can improve the accuracy of internal short circuit detection of the battery cell.

[0007] In some embodiments, when the temperature is less than a first temperature threshold, the speed at which the chemical self-discharge current of the battery cell changes with decreasing temperature is less than a speed threshold.

[0008] In the above solution, when the temperature is less than the first temperature threshold, the internal reaction is suppressed, thereby reducing the chemical self-discharge current of the battery cell and its fluctuation.

[0009] In some embodiments, the target temperature is greater than a second temperature threshold, and when the temperature is less than or equal to the second temperature threshold, the electrochemical system of the battery cell is irreversibly damaged.

[0010] In the above scheme, the target temperature is set to be greater than the second temperature threshold so that the electrochemical system of the battery cell will not be irreversibly damaged, thereby ensuring the availability of the battery cell after testing and reducing the risk of damage to the battery cell.

[0011] In some embodiments, the steady-state current is measured when the charging time of the battery cell is greater than a first preset time.

[0012] In the above solution, setting the first preset time length can conveniently determine when to measure the current, thereby improving measurement efficiency.

[0013] In some embodiments, the target power supply voltage is equal to the cell voltage measured after the voltage of the cell in the target state reaches a stable condition.

[0014] In the above scheme, the voltage of the battery cell in the target state is measured, so that the charging voltage for determining the self-discharge current can be obtained, which is used to obtain the self-discharge current of the battery cell.

[0015] In some embodiments, the battery cell is at the target temperature by any of the following methods: placing the battery cell in an environment with the target temperature for a period greater than a second preset period, or placing the battery cell in an environment with the target temperature until the temperature of the battery cell is measured to be the target temperature.

[0016] In the above solution, a predetermined second preset time period or a method of measuring the temperature of the battery cell may be used to determine whether the battery cell is at the target temperature, so as to facilitate flexible selection according to actual needs.

[0017] In some embodiments, obtaining the self-discharge current of multiple battery cells at a target temperature includes: obtaining multiple steady-state currents of the battery cells measured at different times; and using a first central trend statistical value of the multiple steady-state currents as the self-discharge current of the battery cells.

[0018] In the above scheme, for a battery cell, the first central trend statistical value of its multiple steady-state currents is used as the self-discharge current, which can improve the stability of the self-discharge current, thereby reducing the fluctuation of the self-discharge current between non-short-circuited batteries, reducing the interference of the fluctuation of the self-discharge current of non-short-circuited batteries on the detection, and improving the accuracy of internal short circuit detection of the battery cell.

[0019] In some embodiments, the preset condition includes that the self-discharge current is less than a preset current threshold, or that the distribution of the self-discharge current of the battery cell meets a preset distribution requirement.

[0020] In the above scheme, a preset current threshold is set or a preset distribution requirement is set, and a self-discharge current that is closer to a non-short-circuit state is selected from all self-discharge currents to reasonably determine the current threshold to distinguish between non-short-circuit cells and internal short-circuit cells.

[0021] In some embodiments, the preset conditions include that the distribution of the self-discharge current of the battery cell meets the preset distribution requirements; selecting the self-discharge current that meets the preset conditions from the self-discharge currents of multiple battery cells includes: eliminating the self-discharge currents with discrete distributions from the self-discharge currents of multiple battery cells, and using the remaining self-discharge current as the self-discharge current that meets the preset conditions.

[0022] In the above scheme, the self-discharge current that is closer to the non-short-circuit state is selected by eliminating the self-discharge current with discrete distribution, so as to set a more reasonable current threshold to distinguish between non-short-circuit cells and internal short-circuit cells.

[0023] In some embodiments, based on at least one selected self-discharge current, determining the current threshold includes: performing central tendency statistics and dispersion statistics on the self-discharge current of at least one battery cell to obtain a second central tendency statistical value and a dispersion statistical value; determining a target deviation based on the dispersion statistical value; and adjusting the second central tendency statistical value using the target deviation to obtain the current threshold.

[0024] In the above scheme, adjustments are made based on the selected central trend statistical value of the self-discharge current, and a more reasonable current threshold is set to distinguish between non-short-circuited cells and internally short-circuited cells.

[0025] In some embodiments, it includes: using a preset multiple of the discrete degree statistical value as a target deviation.

[0026] In the above scheme, since the self-discharge current of the non-short-circuited cell has a certain distribution range, the current threshold is determined by considering the discrete degree of the selected self-discharge current, so that a more reasonable current threshold can be obtained to distinguish between the non-short-circuited cell and the internal short-circuited cell.

[0027] In some embodiments, the second central tendency statistic is an average value of the self-discharge current of at least one battery cell, and the dispersion statistic is a standard deviation of the self-discharge current of at least one battery cell.

[0028] In the above scheme, the average value and standard deviation are used to determine the current threshold, so as to distinguish between non-short-circuited cells and internally short-circuited cells.

[0029] In some embodiments, adjusting the second central tendency statistic by using the target deviation to obtain the current threshold includes: taking the sum of the second central tendency statistic and the target deviation as the current threshold.

[0030] In the above scheme, the self-discharge current of the non-short-circuited cell is smaller than the self-discharge current of the internal short-circuited cell. The target deviation is added to the central trend statistical value of the selected self-discharge current to obtain the current threshold, so that the current threshold can distinguish between the non-short-circuited cell and the internal short-circuited cell.

[0031] In some embodiments, based on the relationship between the self-discharge current of each battery cell and the current threshold, detecting whether each battery cell has an internal short circuit includes: in response to the self-discharge current of the battery cell being greater than the current threshold, determining that the battery cell has an internal short circuit; in response to the self-discharge current of the battery cell being less than or equal to the current threshold, determining that the battery cell does not have an internal short circuit.

[0032] In the above scheme, if the self-discharge current of the battery cell is greater than the current threshold, it is determined that the battery cell has an internal short circuit; if the self-discharge current of the battery cell is less than or equal to the current threshold, it is determined that the battery cell does not have an internal short circuit. This realizes the use of the relationship between the self-discharge current of the battery cell and the current threshold to determine whether the battery cell has an internal short circuit.

[0033] The present application provides a detection device for internal short circuit of a battery cell, including an acquisition module, a selection module and a detection module, wherein the acquisition module is used to acquire the self-discharge current of multiple battery cells at a target temperature, wherein the target temperature is less than a first temperature threshold, and the self-discharge current is obtained by measuring the steady-state current of the battery cell when the battery cell in a target state is charged at a constant voltage using a target power supply voltage, wherein the target state includes being at a target temperature and being in a target state of charge, the target power supply voltage is determined based on the battery cell voltage of the battery cell in the target state, and the target state of charge is between 20% and 70%; the selection module is used to select a self-discharge current that meets a preset condition from the self-discharge currents of the multiple battery cells; the detection module is used to determine a current threshold based on at least one selected self-discharge current; and based on the relationship between the self-discharge current of each battery cell and the current threshold, each battery cell is detected to have an internal short circuit.

[0034] The present application provides an electronic device, including a memory and a processor, wherein the processor is used to execute program instructions stored in the memory, and when the program instructions are executed by the processor, the above-mentioned method for detecting an internal short circuit of any battery cell is implemented.

[0035] The present application provides a detection system for an internal short circuit of a battery cell, the system comprising a temperature control box, a current measuring device and equipment, the temperature control box being used to control the ambient temperature of the battery cell so that the battery cell is at a target temperature; the current measuring device being used to measure the current to obtain the self-discharge current of the battery cell when it is at the target temperature; and the equipment being used to execute any of the above-mentioned methods for detecting an internal short circuit of a battery cell.

[0036] The present application provides a computer-readable storage medium having program instructions stored thereon, and when the program instructions are executed by a processor, the method for detecting an internal short circuit of any of the above-mentioned battery cells is implemented.

[0037] In the above scheme, the self-discharge current of the battery cell is obtained when the target temperature is less than the first temperature threshold. The self-discharge current is measured at the target temperature, which can reduce the chemical self-discharge current of the battery cell and its fluctuation, increase the physical self-discharge current, and expand the difference in self-discharge current between the internal short circuit battery cell and the non-short circuit battery cell, thereby improving the accuracy of internal short circuit detection of the battery cell.

[0038] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present application and are used together with the specification to illustrate the technical solution of the present application.

[0040] Figure 1 It is a flowchart of a method for detecting a short circuit inside a battery cell provided in some embodiments of the present application;

[0041] Figure 2 is a circuit diagram of an internal short-circuit battery cell provided in some embodiments of the present application;

[0042] Figure 3 is a first schematic diagram of a current curve of a battery cell constant voltage charging test provided in some embodiments of the present application;

[0043] Figure 4 is a second schematic diagram of a current curve of a battery cell constant voltage charging test provided in some embodiments of the present application;

[0044] Figure 5 It is a schematic diagram of the framework of a device for detecting a short circuit inside a battery cell provided in some embodiments of the present application;

[0045] Figure 6 is a schematic diagram of a framework of an electronic device provided in some embodiments of the present application;

[0046] Figure 7 It is a schematic diagram of the framework of a battery cell internal short circuit detection system provided in some embodiments of the present application;

[0047] Figure 8 It is a schematic diagram of the framework of the computer-readable storage medium provided in some embodiments of the present application. DETAILED DESCRIPTION

[0048] The scheme of the embodiment of the present application is described in detail below in conjunction with the drawings of the specification.

[0049] In the following description, for the purpose of explanation rather than limitation, specific details such as specific subsystem structures, interfaces, and technologies are provided to facilitate a thorough understanding of the present application.

[0050] The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the objects associated before and after are in an "or" relationship. In addition, "many" in this article means two or more than two. In addition, the term "at least one" in this article means any combination of at least two of any one or more of a plurality of, for example, including at least one of A, B, and C, can mean including any one or more elements selected from the set consisting of A, B, and C.

[0051] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0052] As the requirements for battery cell energy density become higher and higher, the design capacity of battery cells becomes higher and higher, the proportion of chemical self-discharge current of battery cells becomes larger and larger, the difficulty of identifying physical self-discharge increases, and the difficulty of detecting internal short circuits in battery cells gradually increases. The current detection method of internal short circuits in battery cells is difficult to eliminate the interference of chemical self-discharge of battery cells, cannot accurately and truly characterize internal short circuits, and cannot accurately detect whether there are internal short circuits in battery cells. For example, there are cases where internal short-circuited batteries are misjudged as non-short-circuited batteries. In the detection method of internal short circuits in battery cells disclosed in the embodiment of the present application, the self-discharge current of the battery cell at a target temperature is obtained, wherein the target temperature is less than a first temperature threshold, at which temperature the chemical self-discharge current of the battery cell and its fluctuation can be reduced, the physical self-discharge current can be increased, the difference in self-discharge current between internal short-circuited batteries and non-short-circuited batteries can be enlarged, and the accuracy of internal short circuit detection in battery cells can be improved.

[0053] The method for detecting an internal short circuit of a battery cell disclosed in the embodiment of the present application is used to detect whether an internal short circuit exists in a battery cell, wherein the type of battery cell to be detected is not limited.

[0054] See also Figure 1 , Figure 1 1 is a flow chart of a method for detecting a short circuit inside a battery cell provided in some embodiments of the present application. Specifically, the method may include:

[0055] Step S110: obtaining self-discharge currents of multiple battery cells at a target temperature.

[0056] The target temperature is less than a first temperature threshold, and it is understood that the first temperature threshold can be set according to actual application requirements. For example, the first temperature threshold can be 25°C.

[0057] It should be noted that the internal self-discharge current of the battery cell is composed of the physical self-discharge current and the chemical self-discharge current. If there is no internal short circuit in the battery cell, the self-discharge current is the chemical self-discharge current. If there is an internal short circuit in the battery cell, the self-discharge current is the sum of the physical self-discharge current and the chemical self-discharge current. When the chemical self-discharge current remains unchanged, there is a certain difference between the self-discharge current of the battery cell with an internal short circuit and the self-discharge current of the battery cell without an internal short circuit.

[0058] Therefore, for each battery cell, whether the battery cell has an internal short circuit can be determined based on the size of its self-discharge current.

[0059] It is understandable that temperature will affect the self-discharge current of the battery cell. When the temperature is lower than the first temperature threshold, the chemical reaction inside the battery cell is suppressed, the magnitude and fluctuation of the chemical self-discharge current are reduced, and the physical self-discharge current is increased, thereby increasing the difference in self-discharge current between the internally short-circuited battery cell and the non-short-circuited battery cell. Therefore, the magnitude of the self-discharge current of the battery cell more accurately reflects the short-circuit condition of the battery cell, thereby improving the accuracy of detecting the internal short circuit of the battery cell.

[0060] It should be noted that since there is a certain difference between the self-discharge current of a battery cell with an internal short circuit and the self-discharge current of a battery cell without an internal short circuit, a current threshold is set as the current critical value for distinguishing internally short-circuited batteries from non-short-circuited batteries. Based on the relationship between the self-discharge current of the battery cell and the current threshold, it can be determined whether the battery cell has an internal short circuit.

[0061] Step S120: determining a current threshold based on a self-discharge current of at least one battery cell.

[0062] Based on the size of the self-discharge current of each battery cell, determining whether each battery cell has an internal short circuit may include: determining a current threshold based on the self-discharge current of at least one battery cell, and detecting whether each battery cell has an internal short circuit based on the size relationship between the self-discharge current of each battery cell and the current threshold, wherein the self-discharge current of at least one battery cell used to determine the current threshold is selected from the self-discharge currents of all battery cells.

[0063] Step S130: Detecting whether each battery cell has an internal short circuit based on the magnitude relationship between the self-discharge current of each battery cell and the current threshold.

[0064] For each cell, the self-discharge current is compared with the current threshold to determine whether the cell has an internal short circuit.

[0065] In the above scheme, the self-discharge current of at least one battery cell is selected to determine the current threshold, so that for each battery cell, its own self-discharge current can be compared with the current threshold to determine whether the battery cell has an internal short circuit.

[0066] In a specific application scenario, specifically, the self-discharge current of a battery cell with an internal short circuit is larger. Detecting whether the battery cell has an internal short circuit may include: in response to the self-discharge current of the battery cell being greater than a current threshold, determining that the battery cell has an internal short circuit; in response to the self-discharge current of the battery cell being less than or equal to the current threshold, determining that the battery cell does not have an internal short circuit.

[0067] In a specific application scenario, detecting whether a battery cell has an internal short circuit may include: in response to a self-discharge current of the battery cell being greater than or equal to a current threshold, determining that the battery cell has an internal short circuit; in response to a self-discharge current of the battery cell being less than the current threshold, determining that the battery cell does not have an internal short circuit.

[0068] In the above scheme, the interference of chemical self-discharge current can be weakened, the current effect of physical self-discharge can be amplified, the internal short characteristics of the battery cell can be highlighted, and the detection rate of the internal short battery cell can be improved. Furthermore, the internal short battery cell can be prevented from being used, thereby improving the safety of the equipment using the battery cell.

[0069] See also Figure 2 , Figure 2 This is a circuit diagram of an internally shorted battery cell provided in some embodiments of the present application.

[0070] Figure 2 The equivalent circuit diagram of a battery cell with an internal short circuit is given, which includes branches a and b connected in parallel. It indicates the short-circuit impedance caused by the internal short of the battery cell. Branch b indicates the battery cell circuit.

[0071] It should be noted that the circuit without short-circuited cells is the cell body circuit, and the short-circuit impedance The resistance value can be approximated to be infinite. The circuit of a completely short-circuited cell can be simplified to a short circuit and the cell body circuit. The short-circuit impedance The resistance value can be approximated to zero.

[0072] in, Indicates the ohmic impedance of the battery cell. represents the electrochemical reaction impedance, represents the diffusion impedance, Represents double layer capacitance. Indicates short-circuit impedance.

[0073] When the state of the battery cell is between the complete short circuit state and the non-short circuit state, the battery cell has an internal short circuit. The degree of the internal short circuit of the battery cell is different, and the corresponding short circuit impedance has different resistance values. Between the complete short circuit state and the non-short circuit state, the leakage rate can be used to indicate the degree of the short circuit of the battery cell. Some batteries with slight short circuits can be called micro-short circuit batteries, and the short circuit current threshold can be set to define micro-short circuit batteries, for example, less than 1mA.

[0074] It is understandable that, at low temperatures below the first temperature threshold, on the one hand, the electrochemical impedance of the battery cell surges, the internal reaction activity drops sharply, the chemical self-discharge current decays exponentially with the temperature drop, and the fluctuation of the chemical self-discharge current between different batteries also decreases. On the other hand, the short-circuit impedance of the battery cell decreases and the physical self-discharge current increases. This can expand the difference in self-discharge current between the internal short-circuit battery cell and the non-short-circuit battery cell, and improve the accuracy of the internal short-circuit detection of the battery cell.

[0075] The electrochemical reaction inside the battery cell is affected by temperature, for example, as the temperature decreases, the internal reaction activity decreases. The above self-discharge current is obtained when the temperature is less than the first temperature threshold. In some embodiments, when the temperature is less than the first temperature threshold, the rate at which the chemical self-discharge current of the battery cell changes with the temperature decreases is less than the rate threshold.

[0076] In some embodiments, the target temperature may be greater than the second temperature threshold. The self-discharge current is obtained when the temperature is greater than the second temperature threshold. When the temperature is less than or equal to the second temperature threshold, the electrochemical system of the battery cell is irreversibly damaged, such as the electrolyte freezing. Exemplarily, the second temperature threshold may be -20°C.

[0077] In a specific application scenario, the first temperature threshold may be 25° C., and the second temperature threshold may be 10° C. It should be noted that a decrease in temperature leads to an increase in the cost of detection, so controlling the temperature above 10° C. can also reduce the cost of detection.

[0078] In some embodiments, the target temperature may be greater than or equal to a second temperature threshold. When the temperature is less than the second temperature threshold, the electrochemical system of the battery cell is irreversibly damaged.

[0079] In the above scheme, the target temperature is set to be greater than the second temperature threshold so that the electrochemical system of the battery cell will not be irreversibly damaged, thereby ensuring the availability of the battery cell after testing and reducing the risk of damage to the battery cell.

[0080] It should be noted that the chemical self-discharge currents of battery cells with the same design are relatively similar. In the method for detecting internal short circuits of battery cells provided in the present application, all battery cells adopt the same design. In a specific application scenario, for a batch of battery cells with the same design, the self-discharge current of each battery cell at the target temperature is obtained respectively, and a current threshold is determined based on the self-discharge current of at least one of the battery cells. The current threshold can be applied to the detection of whether there is an internal short circuit in the batch of battery cells. Furthermore, the current threshold can also be generalized to other battery cells of the same design as the batch of battery cells.

[0081] In some embodiments, the self-discharge current of each battery cell is obtained separately, and the self-discharge current of each battery cell may be obtained when the battery cells are in the same state.

[0082] In some embodiments, for each battery cell, when the target power supply voltage is used to perform constant voltage charging on the battery cell in the target state, the steady-state current of the battery cell can be measured to obtain the self-discharge current of the battery cell.

[0083] The battery cell is charged at a constant voltage until the current meets the current stability condition, and then the current is measured to obtain the steady-state current.

[0084] In some embodiments, a first preset time can be set. When the charging time of the battery cell is longer than the first preset time, it can be considered that the current of the battery cell meets the current stability condition. The first preset time can be a predetermined empirical value. When the charging time of the battery cell is longer than the first preset time, the steady-state current is measured. Setting the first preset time can conveniently determine when to measure the current, thereby improving measurement efficiency.

[0085] The target state includes being at a target temperature and being at a target state of charge.

[0086] It should be noted that when the battery cell is charged at a constant voltage, the battery cell can always be kept at a target temperature, thereby obtaining a self-discharge current of the battery cell at the target temperature. Being at the target state of charge means that the battery cell is at the target state of charge when the test begins.

[0087] In some embodiments, the target state of charge can be set according to actual application needs, for example, the target state of charge is between 20% and 70%.

[0088] In some embodiments, the target state of charge may be between 20% and 30%.

[0089] In some embodiments, the target state of charge may be between 60% and 70%.

[0090] It should be noted that the target state of charge can be set according to actual application needs, and may be specifically related to the type of battery cell.

[0091] It should be noted that the voltage of the battery cell is related to the state of charge. When the state of charge is between 20% and 70%, the fluctuation of the battery cell voltage with the state of charge is small.

[0092] In some embodiments, the temperature of the environment in which the battery cell is located can be set to achieve the battery cell being at the target temperature. Further, the battery cell can be placed in the environment of the target temperature and the placement time is greater than the second preset time, and then the battery cell can be considered to be at the target temperature. Alternatively, the battery cell can be placed in the environment of the target temperature until the temperature of the battery cell is measured to be the target temperature.

[0093] The target power supply voltage is determined based on the cell voltage of the cell in the target state.

[0094] In some embodiments, the target power supply voltage may be equal to the cell voltage of the battery cell in the target state.

[0095] In a specific application scenario, the battery cell can be placed in a target state, and the battery cell voltage can be measured after the voltage reaches a stable condition, and the target power supply voltage can be determined based on the voltage value.

[0096] In one implementation scenario, the battery cell is adjusted to a target state of charge, and the battery cell is placed at a target temperature, and the battery cell voltage at this time is recorded. An external power supply is provided for constant voltage charging of the battery cell, and the power supply voltage is consistent with the recorded battery cell voltage. The battery cell is charged at a constant voltage at the target temperature, and the steady-state current of the battery cell is measured to obtain the self-discharge current.

[0097] In a specific application scenario, the battery cell is adjusted to the target state of charge (SOC). The temperature control box is set to the target temperature, and the battery cell is kept in the temperature control box for a temperature control time of t. After time t, it can be considered that the voltage has reached a stable condition, and then the battery cell voltage V is measured. in . Set the external power supply voltage V out =V in , used to charge the battery cell at a constant voltage and measure the steady-state current of the battery cell.

[0098] In a specific application scenario, the battery cell is charged by constant current charging to adjust the battery cell to the target state of charge. Specifically, the duration of constant current charging can be set, so that when the constant current charging duration reaches a preset duration, the battery cell is considered to have been adjusted to the target state of charge, and at the same time, the battery cell is controlled in the temperature control box for more than a certain period of time, at which time the voltage of the battery cell can be measured as the external power supply voltage.

[0099] In a specific application scenario, the power supply device for charging the battery cell can be a conventional electrochemical charging and discharging device. The battery cell is temperature-controlled by a programmable temperature box, and the battery cell is charged at room temperature through a lead, and the connection port of the battery cell is a pole ear (column).

[0100] In the above scheme, the battery cell is adjusted to the target state of charge by constant current charging for a certain period of time. The actual state of charge of different battery cells may be different. However, because the voltage fluctuates little with the state of charge at the target state of charge, even if there are certain differences between the actual states of charge of the battery cells, the difference in the battery cell voltages measured for different battery cells is relatively small, thereby avoiding the influence of voltage on the self-discharge current. The self-discharge current can more accurately characterize the internal short circuit situation of the battery cell, and the consistency of multiple battery cells is also relatively high, which is conducive to more accurate determination of the threshold value and improving the accuracy of internal short circuit detection.

[0101] It is understandable that the current threshold can be used to distinguish between cells with internal short circuits and cells without short circuits. The self-discharge current of cells with internal short circuits is the chemical self-discharge current. The chemical self-discharge currents of cells with the same design are similar, that is, the self-discharge currents of different cells without short circuits are relatively close, while the self-discharge current of cells with internal short circuits includes not only the chemical self-discharge current but also the physical self-discharge current, which is somewhat different from the self-discharge current of cells without short circuits.

[0102] See also Figure 3 , Figure 3 This is a first schematic diagram of a current curve of a battery cell constant voltage charging test provided in some embodiments of the present application.

[0103] Figure 3 Three current curves are given, namely, the current curve corresponding to a non-short-circuited cell, the current curve corresponding to an internal slightly short-circuited cell, and the current curve of an internal short-circuited cell. Among them, the internal slightly short-circuited cell can also be called a boundary cell, which refers to a cell with a slight internal short circuit. Due to the internal short circuit, its self-discharge current is greater than the self-discharge current of the non-short-circuited cell. Due to the light degree of the short circuit, the difference between its self-discharge current and the self-discharge current of the non-short-circuited cell is smaller than the difference between the self-discharge current of the internal short-circuited cell and the self-discharge current of the non-short-circuited cell.

[0104] Where i0 represents the initial current, i 平衡态1 Indicates the self-discharge current of the non-short-circuited cell, i 平衡态2 Indicates the self-discharge current of the internal micro-short-circuit battery cell, i 平衡态3Indicates the self-discharge current of the internal short-circuited cell. In order to improve the detection rate of the internal short-circuited cell, the key is to increase the difference between the self-discharge current of the internal short-circuited cell and the self-discharge current of the non-short-circuited cell. On the one hand, the fluctuation of the self-discharge current of the non-short-circuited cell is narrowed, the overlap of the self-discharge current of the internal short-circuited cell and the self-discharge current of the non-short-circuited cell is reduced, and the influence of the self-discharge current of the non-short-circuited cell is reduced. On the other hand, the self-discharge current of the internal short-circuited cell is increased, thereby increasing the difference between the self-discharge current of the internal short-circuited cell and the self-discharge current of the non-short-circuited cell.

[0105] It is understandable that during the charging process, after the current meets the current stability condition, the steady-state current can be measured, and the self-discharge current of the battery cell can be determined from the steady-state current. The specific method can be set according to actual application needs.

[0106] In some embodiments, during the charging process of the battery cell, after the current meets the current stability condition, a steady-state current is measured and obtained, and the measured steady-state current can be directly used as the self-discharge current.

[0107] See also Figure 4 , Figure 4 This is a second schematic diagram of a current curve of a battery cell constant voltage charging test provided in some embodiments of the present application.

[0108] like Figure 4 As shown, Figure 4 The solid line in the middle represents the theoretical balance curve of the battery cell, and the dotted line represents the actual measured current curve. During constant voltage charging, the steady-state current can be continuously tested. Due to fluctuations in factors such as temperature, the steady-state current fluctuates around the theoretical balance current (as shown by the dotted line in the figure).

[0109] In some embodiments, a plurality of steady-state currents measured at different times of the battery cell may be obtained, and a first central trend statistical value of the plurality of steady-state currents may be used as the self-discharge current of the battery cell.

[0110] In a specific application scenario, during the cell charging process, when the charging time is longer than the first preset time, the corresponding steady-state current is measured at different times, and the average value of multiple steady-state currents at different times is used as the self-discharge current of the cell.

[0111] In the above scheme, for a battery cell, the first central trend statistical value of its multiple steady-state currents is used as the self-discharge current, which can improve the stability of the self-discharge current, thereby reducing the fluctuation of the self-discharge current between non-short-circuited batteries, reducing the interference of the fluctuation of the self-discharge current of non-short-circuited batteries on the detection, and improving the accuracy of internal short circuit detection of the battery cell.

[0112] The current threshold for distinguishing the two types of cells can be determined based on the self-discharge current of the cells without short circuits. Further, at least some cells can be selected based on the self-discharge current and approximately considered as cells without short circuits. The current threshold is then determined based on the self-discharge current of the selected cells.

[0113] In some embodiments, a self-discharge current that meets a preset condition is selected from the self-discharge currents of multiple battery cells as the self-discharge current for determining the current threshold. The preset condition may include that the self-discharge current is less than a preset current threshold, or that the distribution of the self-discharge current of the battery cell meets a preset distribution requirement.

[0114] In the above scheme, a preset condition is set to select a self-discharge current that is closer to a non-short-circuited cell from all self-discharge currents, so as to reasonably determine a current threshold value to distinguish between a non-short-circuited cell and an internally short-circuited cell.

[0115] In one implementation scenario, the preset condition may include that the self-discharge current is less than a preset current threshold. Specifically, a self-discharge current less than the preset current threshold is selected from the self-discharge currents of all the cells, and the current threshold is determined based on the selected current.

[0116] In the above scheme, the preset current threshold can be determined based on experience. This preset current threshold can be relatively low, and it can be clear that the battery cells whose self-discharge current is less than the preset current threshold are most likely to be non-short-circuited batteries, so that the self-discharge current that is closer to the non-short-circuited state can be selected.

[0117] In one implementation scenario, the preset condition may include that the distribution of the self-discharge current of the battery cell meets the preset distribution requirement, and the preset distribution requirement may be a requirement for the concentration of the current distribution, so as to select a self-discharge current with a more concentrated distribution. Specifically, from the self-discharge currents of all battery cells, the self-discharge currents with discrete distributions are eliminated, and the remaining self-discharge currents are used as the self-discharge currents that meet the preset conditions.

[0118] In the above scheme, the self-discharge current that is closer to the non-short-circuit state is selected by eliminating the self-discharge current with discrete distribution, so as to set a more reasonable current threshold to distinguish between non-short-circuit cells and internal short-circuit cells.

[0119] It is understandable that the self-discharge current that meets the preset conditions can be considered as the self-discharge current of a non-short-circuited cell, and can be used to characterize the chemical self-discharge current of a non-short-circuited cell. The self-discharge current of an internal short-circuited cell is the physical self-discharge current added to the chemical self-discharge current. Furthermore, the current threshold can be set by considering the acceptable degree of internal short-circuit of the cell and combining it with the chemical self-discharge current of the non-short-circuited cell.

[0120] In some embodiments, determining the current threshold may include: performing central tendency statistics on the self-discharge current of at least one battery cell to obtain a second central tendency statistical value, and adjusting the second central tendency statistical value using a target deviation to obtain the current threshold.

[0121] Among them, at least one selected cell can be considered as a non-short-circuited cell, and the central trend statistics of all selected self-discharge currents are performed to characterize the chemical self-discharge current of the cell without short circuit. The target deviation is adjusted based on the chemical self-discharge current of the non-short-circuited cell, taking into account the acceptable degree of internal short circuit of the cell.

[0122] In a specific application scenario, the sum of the second central tendency statistical value and the target deviation may be used as the current threshold.

[0123] The target deviation may be a preset value, or may be determined based on the discrete degree of the self-discharge current.

[0124] In one implementation scenario, the selected self-discharge current is subjected to central tendency statistics and dispersion degree statistics to obtain a second central tendency statistical value and a dispersion degree statistical value, and the target deviation is determined based on the dispersion degree statistical value.

[0125] It is understandable that the chemical self-discharge currents of cells of the same design are similar, but the chemical self-discharge currents of different cells may also be different. It can be considered to be subject to the distribution N( ,in, Represents the average value of the chemical self-discharge current of multiple cells, Represents the standard deviation of the chemical self-discharge current of multiple cells. Since the self-discharge current of a non-short-circuited cell has a certain distribution range, the current threshold is determined by considering the discrete degree of the selected self-discharge current, so that a more reasonable current threshold can be obtained to distinguish between non-short-circuited cells and internal short-circuited cells.

[0126] In some embodiments, determining the current threshold may further include: performing discrete degree statistics on the self-discharge current of at least one battery cell to obtain a discrete degree statistical value of the self-discharge current of at least one battery cell, and using a preset multiple of the discrete degree statistical value as a target deviation.

[0127] In one implementation scenario, the average value may be used as the second central tendency statistical value. Of course, other statistical values ​​may also be used to characterize the central tendency of the selected self-discharge current, which may be selected according to actual application requirements.

[0128] In one implementation scenario, the standard deviation may be used as a statistical value of the degree of dispersion. Of course, other statistical values ​​may also be used to characterize the degree of dispersion of the selected self-discharge current, which may be selected according to actual application requirements.

[0129] In a specific application scenario, the sum of the mean value and three times the standard deviation can be used as the current threshold, expressed as .

[0130] See also Figure 5 , Figure 5 It is a schematic diagram of the framework of a device for detecting internal short circuit of a battery cell provided in some embodiments of the present application.

[0131] The detection device 50 for internal short circuit of battery cells includes an acquisition module 51, a selection module 52 and a detection module 53. The acquisition module 51 is used to acquire the self-discharge current of multiple battery cells at a target temperature, wherein the target temperature is less than a first temperature threshold, and the self-discharge current is obtained by measuring the steady-state current of the battery cell when the battery cell in a target state is charged at a constant voltage using a target power supply voltage, wherein the target state includes being at a target temperature and being in a target state of charge, and the target power supply voltage is determined based on the battery cell voltage of the battery cell in the target state, and the target state of charge is between 20% and 70%; the selection module 52 is used to select a self-discharge current that meets a preset condition from the self-discharge currents of multiple battery cells; the detection module 53 is used to determine a current threshold based on at least one selected self-discharge current; and based on the relationship between the self-discharge current of each battery cell and the current threshold, each battery cell is detected to have an internal short circuit.

[0132] In the above scheme, the self-discharge current of multiple battery cells at the target temperature is obtained, the target temperature is less than the first temperature threshold, and the steady-state current is measured at the target temperature to obtain the self-discharge current, which can reduce the chemical self-discharge current of the battery cell and its fluctuation, increase the physical self-discharge current, and expand the difference in self-discharge current between the internal short circuit battery cell and the non-short circuit battery cell. The threshold is determined based on at least one measured self-discharge current to distinguish whether the battery cell has an internal short circuit, which can improve the accuracy of the internal short circuit detection of the battery cell. Furthermore, the battery cell is set to be in the target state of charge, and the consistency of multiple battery cells is also relatively high, which is conducive to more accurate determination of the threshold and improves the accuracy of internal short circuit detection.

[0133] In some embodiments, when the temperature is less than a first temperature threshold, the speed at which the chemical self-discharge current of the battery cell changes with decreasing temperature is less than a speed threshold.

[0134] In the above solution, when the temperature is less than the first temperature threshold, the internal reaction is suppressed, thereby reducing the chemical self-discharge current of the battery cell and its fluctuation.

[0135] In some embodiments, the target temperature is greater than a second temperature threshold, and when the temperature is less than or equal to the second temperature threshold, the electrochemical system of the battery cell is irreversibly damaged.

[0136] In the above scheme, the target temperature is set to be greater than the second temperature threshold so that the electrochemical system of the battery cell will not be irreversibly damaged, thereby ensuring the availability of the battery cell after testing and reducing the risk of damage to the battery cell.

[0137] In some embodiments, the steady-state current is measured when the charging time of the battery cell is greater than a first preset time.

[0138] In the above solution, setting the first preset time length can conveniently determine when to measure the current, thereby improving measurement efficiency.

[0139] In some embodiments, the target power supply voltage is equal to the cell voltage measured after the voltage of the cell in the target state reaches a stable condition.

[0140] In the above scheme, the voltage of the battery cell in the target state is measured, so that the charging voltage for determining the self-discharge current can be obtained, which is used to obtain the self-discharge current of the battery cell.

[0141] In some embodiments, the battery cell is at the target temperature by any of the following methods: placing the battery cell in an environment with the target temperature for a period greater than a second preset period, or placing the battery cell in an environment with the target temperature until the temperature of the battery cell is measured to be the target temperature.

[0142] In the above solution, a predetermined second preset time period or a method of measuring the temperature of the battery cell may be used to determine whether the battery cell is at the target temperature, so as to facilitate flexible selection according to actual needs.

[0143] In some embodiments, obtaining the self-discharge current of the plurality of battery cells at the target temperature includes: obtaining a plurality of steady-state currents of the battery cells at different times; and using a first central trend statistical value of the plurality of steady-state currents as the self-discharge current of the battery cells.

[0144] In the above scheme, for a battery cell, the first central trend statistical value of its multiple steady-state currents is used as the self-discharge current, which can improve the stability of the self-discharge current, thereby reducing the fluctuation of the self-discharge current between non-short-circuited batteries, reducing the interference of the fluctuation of the self-discharge current of non-short-circuited batteries on the detection, and improving the accuracy of internal short circuit detection of the battery cell.

[0145] In some embodiments, the preset condition includes that the self-discharge current is less than a preset current threshold, or that the distribution of the self-discharge current of the battery cell meets a preset distribution requirement.

[0146] In the above scheme, a preset current threshold value or a preset distribution requirement is set to select a self-discharge current that is closer to the condition of a cell without a short circuit from all self-discharge currents, so as to reasonably determine the current threshold value to distinguish between cells without a short circuit and cells with an internal short circuit.

[0147] In some embodiments, the preset conditions include that the distribution of the self-discharge current of the battery cell meets the preset distribution requirements; the selection module is used to select the self-discharge current that meets the preset conditions from the self-discharge currents of multiple battery cells, specifically including: from the self-discharge currents of multiple battery cells, eliminating the self-discharge currents with discrete distributions, and using the remaining self-discharge current as the self-discharge current that meets the preset conditions.

[0148] In the above scheme, the self-discharge current that is closer to the situation of no short-circuit cells is selected by eliminating the self-discharge current with discrete distribution, so as to set a more reasonable current threshold to distinguish between no short-circuit cells and internal short-circuit cells.

[0149] In some embodiments, the detection module 53 is used to determine the current threshold based on at least one selected self-discharge current, specifically including: performing central tendency statistics and discrete degree statistics on the self-discharge current of at least one battery cell to obtain a second central tendency statistical value and a discrete degree statistical value; determining a target deviation based on the discrete degree statistical value; and using the target deviation to adjust the second central tendency statistical value to obtain the current threshold.

[0150] In the above scheme, adjustments are made based on the selected central trend statistical value of the self-discharge current, and a more reasonable current threshold is set to distinguish between non-short-circuited cells and internally short-circuited cells.

[0151] In some embodiments, the detection module 53 is used to determine the target deviation based on the discrete degree statistic value, specifically including: taking a preset multiple of the discrete degree statistic value as the target deviation.

[0152] In the above scheme, since the self-discharge current of the non-short-circuited cell has a certain distribution range, the current threshold is determined by considering the discrete degree of the selected self-discharge current, so that a more reasonable current threshold can be obtained to distinguish between the non-short-circuited cell and the internal short-circuited cell.

[0153] In some embodiments, the second central tendency statistic is an average value of the self-discharge current of at least one battery cell, and the dispersion statistic is a standard deviation of the self-discharge current of at least one battery cell.

[0154] In the above scheme, the average value and standard deviation are used to determine the current threshold, so as to distinguish between non-short-circuited cells and internally short-circuited cells.

[0155] In some embodiments, the detection module 53 is used to adjust the second central tendency statistic by using the target deviation to obtain the current threshold, specifically including: taking the sum of the second central tendency statistic and the target deviation as the current threshold.

[0156] In the above scheme, the self-discharge current of the non-short-circuited cell is smaller than the self-discharge current of the internal short-circuited cell. The target deviation is added to the central trend statistical value of the selected self-discharge current to obtain the current threshold, so that the current threshold can distinguish between the non-short-circuited cell and the internal short-circuited cell.

[0157] In some embodiments, the detection module 53 is used to detect whether each battery cell has an internal short circuit based on the relationship between the self-discharge current of each battery cell and the current threshold, specifically including: in response to the self-discharge current of the battery cell being greater than the current threshold, determining that the battery cell has an internal short circuit; in response to the self-discharge current of the battery cell being less than or equal to the current threshold, determining that the battery cell does not have an internal short circuit.

[0158] In the above scheme, if the self-discharge current of the battery cell is greater than the current threshold, it is determined that the battery cell has an internal short circuit; if the self-discharge current of the battery cell is less than or equal to the current threshold, it is determined that the battery cell does not have an internal short circuit. This realizes the use of the relationship between the self-discharge current of the battery cell and the current threshold to determine whether the battery cell has an internal short circuit.

[0159] See also Figure 6 , Figure 6 It is a schematic diagram of the framework of an electronic device provided in some embodiments of the present application.

[0160] The electronic device 60 includes a memory 61 and a processor 62 coupled to each other, and the processor 62 is used to execute program instructions stored in the memory 61 to implement the above-mentioned method for detecting an internal short circuit of any battery cell. In a specific implementation scenario, the electronic device 60 may include but is not limited to: a microcomputer, a server, and in addition, the electronic device 60 may also include a mobile device such as a laptop computer and a tablet computer, which is not limited here.

[0161] Specifically, the processor 62 is used to control itself and the memory 61 to implement the above-mentioned detection method of internal short circuit of any battery cell. The processor 62 can also be called a CPU (Central Processing Unit). The processor 62 may be an integrated circuit chip with signal processing capabilities. The processor 62 can also be a general-purpose processor, a digital signal processor (Digital Signal Processor, DSP), an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC), a field-programmable gate array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. In addition, the processor 62 can be implemented by an integrated circuit chip.

[0162] See also Figure 7 , Figure 7 It is a schematic diagram of the framework of a battery cell internal short circuit detection system provided in some embodiments of the present application.

[0163] The detection system 70 for internal short circuit of a battery cell includes a temperature control box 71, a current measuring device 72 and a device 73. The temperature control box 71 is used to control the temperature of the environment in which the battery cell is located so that the battery cell is at a target temperature; the current measuring device 72 is used to measure the current to obtain the self-discharge current of the battery cell at the target temperature; and the device 73 is used to perform any of the above-mentioned detection methods for internal short circuit of a battery cell. The temperature control box 71 can be used to place the battery cell therein, so as to control the temperature of the environment in which the battery cell is located.

[0164] See also Figure 8 , Figure 8 It is a schematic diagram of the framework of the computer-readable storage medium provided in some embodiments of the present application.

[0165] The computer-readable storage medium 80 stores program instructions 81 that can be executed by a processor. When the program instructions 81 are executed by the processor, they are used to implement any of the above-mentioned methods for detecting an internal short circuit of a battery cell.

[0166] The above description of various embodiments tends to emphasize the differences between the various embodiments. The same or similar aspects can be referenced to each other, and for the sake of brevity, they will not be repeated herein.

[0167] In the several embodiments provided in the present application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device implementation described above is only schematic. For example, the division of modules or units is only a logical function division. There may be other division methods in actual implementation, such as units or components can be combined or integrated into another subsystem, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0168] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit. If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or part of the contribution to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor (processor) to perform all or part of the steps of each implementation method of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program code.

Claims

1. A method for detecting an internal short circuit of a battery cell, characterized in that: The method comprises: Obtaining self-discharge currents of a plurality of battery cells at a target temperature, wherein the target temperature is less than a first temperature threshold, and the self-discharge current is obtained by measuring a steady-state current of the battery cell when a target power supply voltage is used to perform constant voltage charging on the battery cell in a target state, wherein the target state includes being at the target temperature and being at a target state of charge, the target power supply voltage is equal to a battery cell voltage measured after the voltage of the battery cell in the target state reaches a stable condition, and each of the battery cells is in the target state of charge by performing constant current charging on the battery cell for a preset time, and the target state of charge is between 20% and 70%; Selecting a self-discharge current that meets a preset condition from the self-discharge currents of the plurality of battery cells; determining a current threshold based on at least one of the selected self-discharge currents; Based on the magnitude relationship between the self-discharge current of each battery cell and the current threshold, it is detected whether each battery cell has an internal short circuit.

2. The method according to claim 1, characterized in that When the temperature is lower than the first temperature threshold, the speed at which the chemical self-discharge current of the battery cell changes with decreasing temperature is lower than a speed threshold.

3. The method according to claim 1, characterized in that The target temperature is greater than a second temperature threshold, and when the temperature is less than or equal to the second temperature threshold, the electrochemical system of the battery cell is irreversibly damaged.

4. The method according to claim 1, characterized in that: The steady-state current is measured when the charging time of the battery cell is greater than a first preset time; And / or, the battery cell is at the target temperature by any of the following methods: placing the battery cell in an environment with the target temperature for a period of time greater than a second preset period of time; placing the battery cell in an environment with the target temperature until the temperature of the battery cell is measured to be the target temperature.

5. The method according to claim 1, characterized in that The obtaining of the self-discharge current of the plurality of battery cells at the target temperature comprises: Acquire multiple steady-state currents of the battery cell measured at different times; A first central tendency statistical value of the plurality of steady-state currents is used as the self-discharge current of the battery cell.

6. The method according to claim 1, characterized in that The preset condition includes that the self-discharge current is less than a preset current threshold, or that the distribution of the self-discharge current of the battery cell meets a preset distribution requirement.

7. The method according to claim 6, characterized in that The preset condition includes that the distribution of the self-discharge current of the battery cell meets the preset distribution requirement; the self-discharge current that meets the preset condition is selected from the self-discharge currents of the plurality of battery cells and comprises: From the self-discharge currents of the plurality of battery cells, the self-discharge currents with discrete distribution are eliminated, and the remaining self-discharge currents are used as the self-discharge currents that meet the preset conditions.

8. The method according to claim 1, characterized in that The determining of the current threshold based on the selected at least one self-discharge current comprises: Performing central tendency statistics and dispersion degree statistics on the self-discharge current of at least one of the battery cells to obtain a second central tendency statistical value and a dispersion degree statistical value; Determining a target deviation based on the dispersion statistics; The second central tendency statistical value is adjusted using the target deviation to obtain the current threshold.

9. The method according to claim 8, characterized in that Determining the target deviation based on the discrete degree statistics includes: A preset multiple of the discrete degree statistical value is used as the target deviation.

10. The method according to claim 8, characterized in that The second central tendency statistic is an average value of the self-discharge current of at least one of the battery cells, and the dispersion statistic is a standard deviation of the self-discharge current of at least one of the battery cells.

11. The method according to claim 8, characterized in that The adjusting the second central tendency statistical value by using the target deviation to obtain the current threshold comprises: The sum of the second central tendency statistical value and the target deviation is used as the current threshold.

12. The method according to claim 1, characterized in that The detecting whether each of the battery cells has an internal short circuit based on the magnitude relationship between the self-discharge current of each of the battery cells and the current threshold comprises: In response to the self-discharge current of the battery cell being greater than the current threshold, determining that the battery cell has an internal short circuit; In response to the self-discharge current of the battery cell being less than or equal to the current threshold, it is determined that the battery cell does not have an internal short circuit.

13. A device for detecting internal short circuit of a battery cell, characterized in that: include: an acquisition module, configured to acquire self-discharge currents of a plurality of battery cells at a target temperature, wherein the target temperature is less than a first temperature threshold, and the self-discharge current is obtained by measuring a steady-state current of the battery cell when a target power supply voltage is used to perform constant voltage charging on the battery cell in a target state, wherein the target state includes being at the target temperature and being at a target state of charge, the target power supply voltage is equal to a battery cell voltage measured after the voltage of the battery cell in the target state reaches a stable condition, and each of the battery cells is in the target state of charge by performing constant current charging on the battery cell for a preset time, and the target state of charge is between 20% and 70%; A selection module, configured to select a self-discharge current that meets a preset condition from the self-discharge currents of the plurality of battery cells; The detection module is used to determine a current threshold based on at least one selected self-discharge current; and detect whether each of the battery cells has an internal short circuit based on the magnitude relationship between the self-discharge current of each of the battery cells and the current threshold.

14. An electronic device, characterized in that: The method comprises a memory and a processor, wherein the memory stores program instructions, and when the program instructions are executed by the processor, the method according to any one of claims 1 to 12 is implemented.

15. A detection system for internal short circuit of a battery cell, characterized in that: The system includes a temperature control box, a current measuring device and equipment, wherein the temperature control box is used to control the ambient temperature of the battery cell so that the battery cell is at a target temperature; the current measuring device is used to measure the current to obtain the self-discharge current of the battery cell when it is at the target temperature; and the equipment is used to execute the method described in any one of claims 1 to 12 above.

16. A computer-readable storage medium having program instructions stored thereon, characterized in that: When the program instructions are executed by a processor, the method according to any one of claims 1 to 12 is implemented.

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