Method and device for detecting lithium battery abnormality, battery management system and battery system

Abstract

The embodiment of the application provides a kind of detection lithium battery abnormal method and device, battery management system and battery system, the method includes obtaining the SOC value in the charging process of lithium battery, wherein, SOC value is the ratio of battery remaining capacity and battery nominal capacity, the size of charging current is changed at the moment corresponding to any SOC value, and the response signal in the duration period of charging current change is obtained, whether lithium battery is abnormal is determined according to the response signal of the moment corresponding to multiple SOC values. By the above-mentioned mode, the nondestructive testing of lithium ion battery abnormality can be realized, and the operation is simple and the accuracy is higher.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method and apparatus for detecting abnormalities in lithium batteries, a battery management system, and a battery system. Background Technology

[0002] With the advancement of technology, lithium-ion batteries have been widely used in consumer electronics, energy storage and electric vehicles due to their significant advantages such as high energy density, long cycle life and green and pollution-free operation. In the performance evaluation of lithium-ion batteries, an essential technical indicator is cycle life, including cycle life under various temperatures and even some extreme application environments.

[0003] In cycle testing, in addition to focusing on the battery's capacity retention rate, whether and when abnormalities occur during the cycle are also important lifespan evaluation indicators. As we all know, once a battery malfunctions, it may not only accelerate performance degradation but also cause internal short circuits, posing safety hazards.

[0004] Currently, the most common method for determining whether a lithium-ion battery is abnormal is to charge the battery at different rates and temperatures, then disassemble it, visually inspect it, and subjectively assess the abnormal state and severity. However, this method relies heavily on human experience, which not only introduces errors due to subjective judgment but is also complex and inefficient. Furthermore, lithium-ion batteries, especially power batteries, are large and heavy, and some even have steel casings, posing safety hazards during disassembly and requiring significant manpower and resources. Summary of the Invention

[0005] This application aims to provide a method and apparatus for detecting abnormalities in lithium batteries, a battery management system and a battery system, which can achieve non-destructive testing of abnormalities in lithium-ion batteries, and is simple to operate and highly accurate.

[0006] To achieve the above objectives, in a first aspect, this application provides a method for detecting abnormalities in lithium batteries, comprising:

[0007] The SOC value during the charging process of the lithium battery is obtained, wherein the SOC value is the ratio of the remaining battery capacity to the nominal battery capacity;

[0008] The charging current is changed at any time corresponding to the SOC value, and the response signal is obtained during the duration of the charging current change.

[0009] The lithium battery is determined to be abnormal based on the response signals at the corresponding times of the multiple SOC values.

[0010] In one alternative approach, changing the magnitude of the charging current at any given time corresponding to the SOC value includes:

[0011] At any given time corresponding to the SOC value, an instruction to change the current is output to change the magnitude of the charging current, wherein the instruction to change the current includes an instruction to change the magnitude of the charging current and an instruction to specify the duration of the change in the charging current.

[0012] In one alternative approach, changing the magnitude of the charging current at any given time corresponding to the SOC value includes:

[0013] The magnitude of the charging current is changed at at least three times corresponding to the SOC value.

[0014] In one alternative approach, the response signal is a voltage signal.

[0015] In one alternative approach, determining whether the lithium battery is abnormal based on the response signals corresponding to multiple SOC values ​​at different times includes:

[0016] Obtain the first voltage value in the Nth voltage signal at the start of the first preset duration, and obtain the second voltage value in the Nth voltage signal at the end of the first preset duration, wherein the first preset duration is any time period within the duration of each change in charging current;

[0017] The Nth voltage change value is obtained by the absolute value of the difference between the first voltage value and the second voltage value in the Nth voltage signal;

[0018] The presence or absence of an abnormality in the lithium battery is determined based on the voltage change value.

[0019] In one alternative approach, determining whether the lithium battery is abnormal based on the voltage change value includes:

[0020] The Nth data point is obtained based on the Nth voltage change value and its corresponding SOC value;

[0021] Based on the data points, determine whether the lithium battery is malfunctioning.

[0022] In one alternative approach, determining whether the lithium battery is abnormal based on the voltage change value includes:

[0023] Get the first current value of the charging current at any time before each change in the charging current;

[0024] Calculate the ratio of the Nth voltage change value to the first current value, and record it as the Nth first resistance change value;

[0025] Based on the Nth first resistance change value and its corresponding SOC value, obtain the Nth data point;

[0026] Based on the data points, determine whether the lithium battery is malfunctioning.

[0027] In one alternative approach, determining whether the lithium battery is abnormal based on the voltage change value includes:

[0028] Obtain the second current value of the charging current at any time within the duration of each change in charging current;

[0029] Calculate the ratio of the Nth voltage change value to the second current value, and record it as the Nth second resistance change value;

[0030] Based on the Nth second resistance change value and its corresponding SOC value, obtain the Nth data point;

[0031] Based on the data points, determine whether the lithium battery is malfunctioning.

[0032] In one alternative approach, determining whether the lithium battery is abnormal based on the voltage change value includes:

[0033] Obtain the third current value of the charging current at any time before each change of the charging current, and the fourth current value of the charging current at any time during the duration of each change of the charging current.

[0034] Calculate the absolute value of the difference between the third current value and the fourth current value;

[0035] Calculate the ratio of the Nth voltage change value to the absolute value, and record it as the Nth third resistance change value;

[0036] The Nth data point is obtained based on the Nth change value of the third resistance and its corresponding SOC value;

[0037] Based on the data points, determine whether the lithium battery is malfunctioning.

[0038] In one alternative approach, determining whether the lithium battery is abnormal based on the data points includes:

[0039] Obtain the Nth slope between the (N+1)th data point and the Nth data point, and the (N+1)th slope between the (N+2)th data point and the (N+1)th data point;

[0040] If the slope of the Nth digit is greater than 0 and the slope of the (N+1)th digit is less than 0, then the lithium battery is determined to be abnormal.

[0041] Secondly, this application also provides a device for detecting abnormalities in lithium batteries, comprising:

[0042] The first acquisition unit is used to acquire the SOC value during the charging process of the lithium battery, wherein the SOC value is the ratio of the remaining battery capacity to the nominal battery capacity.

[0043] The second acquisition unit is used to change the magnitude of the charging current at any time corresponding to the SOC value, and acquire the response signal within the duration of the change in the charging current.

[0044] The determining unit is used to determine whether the lithium battery is abnormal based on the response signals at the corresponding times of the multiple SOC values.

[0045] Thirdly, this application also provides a device for detecting abnormalities in lithium batteries, comprising:

[0046] A memory; and a processor coupled to the memory, the processor being configured to perform the method described above based on instructions stored in the memory.

[0047] Fourthly, this application also provides a battery management system, including the apparatus for detecting lithium battery abnormalities as described above.

[0048] Fifthly, this application also provides a battery system, including a rechargeable battery and a battery management system as described above.

[0049] Sixthly, this application also provides an electric vehicle, including: a charging and discharging device and a battery system as described above.

[0050] In a seventh aspect, this application also provides a computer-readable storage medium, comprising: storing computer-executable instructions configured as described above.

[0051] The beneficial effects of the embodiments of this application are as follows: The method for detecting abnormalities in lithium batteries provided by this application is to first obtain the SOC value of the lithium battery during the charging process, where SOC is the ratio of the remaining battery capacity to the nominal battery capacity. Then, the magnitude of the charging current can be changed at any time corresponding to the SOC value, and the response signal within the duration of the charging current change is obtained. Finally, the abnormality of the lithium battery is determined based on the response signals at multiple SOC values. This application can perform the detection without disassembling the battery, which is a non-destructive testing method. Moreover, it only requires changing the magnitude of the charging current during the charging process, which is simple to operate. At the same time, the abnormality is determined based on the automatically generated response signal, which eliminates the error caused by subjective judgment and has high accuracy. Attached Figure Description

[0052] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0053] Figure 1 This is a schematic diagram of an application scenario disclosed in an embodiment of this application;

[0054] Figure 2 This is a flowchart illustrating a method for detecting lithium battery abnormalities disclosed in an embodiment of this application.

[0055] Figure 3a This is a schematic diagram of changing the magnitude of the charging current at any time corresponding to any SOC value, as disclosed in an embodiment of this application.

[0056] Figure 3b This is a schematic diagram of changing the magnitude of the charging current at any time corresponding to any SOC value, as disclosed in another embodiment of this application;

[0057] Figure 4 This is a schematic diagram of a response signal disclosed in an embodiment of this application;

[0058] Figure 5 This is a schematic diagram of a method for determining lithium battery malfunctions based on at least three response signals, as disclosed in an embodiment of this application.

[0059] Figure 6 This is a schematic diagram of a response signal disclosed in another embodiment of this application;

[0060] Figure 7 This is a schematic diagram of a method for determining lithium battery abnormalities based on voltage change values, as disclosed in an embodiment of this application.

[0061] Figure 8 This is a schematic diagram of data points obtained for different first preset durations as disclosed in an embodiment of this application;

[0062] Figure 9a This is a schematic diagram of the acquired data points disclosed in an embodiment of this application;

[0063] Figure 9b This is a schematic diagram of the acquired data points disclosed in another embodiment of this application;

[0064] Figure 10 This is a schematic diagram of the response signal disclosed in another embodiment of this application;

[0065] Figure 11 This is a schematic diagram of a method for determining lithium battery malfunctions based on a first resistance change value, as disclosed in an embodiment of this application.

[0066] Figure 12a This is a schematic diagram of data points obtained from voltage change values ​​according to an embodiment of this application;

[0067] Figure 12b This is a schematic diagram of data points obtained from the change value of the first resistance, as disclosed in an embodiment of this application;

[0068] Figure 12c This is a schematic diagram of data points obtained from the change value of the first resistance, as disclosed in another embodiment of this application;

[0069] Figure 13 This is a schematic diagram of a method for determining lithium battery malfunctions based on a second resistance change value, as disclosed in an embodiment of this application.

[0070] Figure 14 This is a schematic diagram of data points obtained from the change value of the second resistance, as disclosed in an embodiment of this application;

[0071] Figure 15 This is a schematic diagram of a method for determining lithium battery abnormalities based on a change in a third resistance value, as disclosed in an embodiment of this application.

[0072] Figure 16 This is a schematic diagram of data points obtained from the change value of a third resistor, as disclosed in an embodiment of this application;

[0073] Figure 17 This is a schematic diagram illustrating the determination of lithium battery anomalies under different charging currents according to an embodiment of this application.

[0074] Figure 18 This is a schematic diagram illustrating how different values ​​of charging current are changed to determine lithium battery malfunctions, as disclosed in an embodiment of this application.

[0075] Figure 19 This is a schematic diagram of determining lithium battery abnormalities based on different first preset durations, as disclosed in an embodiment of this application;

[0076] Figure 20 This is a schematic diagram of a device for detecting lithium battery abnormalities disclosed in an embodiment of this application;

[0077] Figure 21 This is a schematic diagram of a device for detecting lithium battery abnormalities disclosed in another embodiment of this application.

[0078] The accompanying drawings are not drawn to scale. Detailed Implementation

[0079] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0080] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0081] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0082] This application provides a method for detecting abnormalities in lithium batteries. This method only requires a single charging process of the lithium battery to determine whether an abnormality has occurred. Compared with the prior art, this application can directly determine whether the battery is abnormal in real time during the lithium battery charging process, and it is not limited to the charging method of the lithium battery. For example, this method is applicable to both constant current charging and variable current charging.

[0083] It should be noted that the anomaly in this application mainly refers to a type of performance anomaly during battery use, and this performance anomaly is caused by lithium plating inside the lithium battery.

[0084] When a normal lithium battery is charging, lithium ions are released from the cathode active material and embedded into the layers of the anode (graphite as an example) active material. Lithium plating in lithium batteries refers to the phenomenon where, after being released, lithium ions are unable to embed into the layers of the anode active material due to obstruction, and instead deposit and grow on the surface of the anode electrode.

[0085] Therefore, after lithium plating occurs in a lithium battery, the following abnormal situations may occur.

[0086] First, the self-discharge rate of lithium batteries undergoing lithium plating increases. Therefore, in practical applications, such as in electric vehicles, lithium batteries are typically stored in battery packs. This anomaly leads to a greater voltage difference between the lithium battery undergoing plating and other batteries. A battery pack, also known as a battery stack, usually contains multiple lithium batteries connected in parallel or series. This is because, when a normal lithium battery is not in use, its voltage gradually decreases. If lithium plating occurs, it causes a micro-short circuit within the battery, exacerbating the voltage drop and resulting in a voltage inconsistency between the lithium battery undergoing plating and the other lithium batteries in the battery pack.

[0087] Second, lithium batteries that undergo lithium plating experience accelerated capacity decay and shortened lifespan. This is because, on the one hand, the lithium plating process consumes active lithium ions inside the battery, reducing the total usable lithium ion content and causing capacity loss; on the other hand, the deposited lithium ions form an inert layer between the anode and the separator, hindering lithium ion transport and increasing polarization during charging and discharging, which also leads to capacity loss.

[0088] Third, lithium batteries that undergo lithium plating may experience thermal runaway, leading to fire and explosion. This is because the deposited lithium dendrites accumulate and eventually pierce the separator, forming a large-area short circuit. This causes the temperature at the short circuit point to rise sharply, resulting in thermal runaway within the lithium battery and ultimately, fire and explosion.

[0089] In summary, the method for detecting lithium battery abnormalities provided in this application can detect whether the lithium battery has undergone lithium plating, thereby detecting whether the aforementioned abnormalities have occurred.

[0090] To facilitate understanding of this application, we will first introduce the applicable scenarios. Please refer to [link / reference]. Figure 1 . Figure 1 This application scenario illustrates one use case for the lithium battery anomaly detection method provided in this application, which includes an electric vehicle 10 and a charging station 11. For example... Figure 1As shown, the electric vehicle 10 is equipped with a BMS101 (BMS stands for Battery Management System) and a lithium battery 102. The BMS101 is a control system that protects the lithium battery 102 and monitors its operating status at all times. The charging pile 11 is used to charge the lithium battery 102, and this charging process is controlled by the BMS101. Therefore, during charging, the BMS101 can control the charging method of the charging pile 11 to charge the lithium battery 102, such as constant current charging or variable current charging. Simultaneously, the BMS101 can also control the charging current of the charging pile 11 to charge the lithium battery 102 and read the parameter changes of the lithium battery 102, thereby determining in real time whether the lithium battery 102 is malfunctioning. The above method can non-destructively detect whether the lithium battery 102 is abnormal during the charging process, so that corresponding solutions can be taken in time to avoid accidents caused by abnormalities of the lithium battery 102, such as preventing major safety accidents such as explosions caused by short circuits in the lithium battery 102.

[0091] Figure 2 This is a flowchart illustrating a method for detecting lithium battery abnormalities disclosed in an embodiment of this application, as shown below. Figure 2 As shown, the method includes:

[0092] 201: Obtain the SOC value during the charging process of the lithium battery.

[0093] The charging process can include constant current charging or variable current charging. Constant current charging mainly refers to keeping the charging current constant during the charging process. For example, if a charging rate of 1C is always used, 1C means that at this charging rate, it takes 1 hour for the lithium battery to be fully charged from zero.

[0094] The variable current charging process typically refers to a step charge process, which divides the variable current charging process into multiple sub-constant current charging processes, each with a different charging rate (representing a segment of constant current charging). For example, the variable current charging process can be divided into three segments, where the first segment has a charging rate of 2C, the second segment has a charging rate of 1.8C, and the third segment has a charging rate of 1.5C.

[0095] State of Charge (SOC) is the ratio of a battery's remaining charge to its nominal capacity. During charging, the SOC value changes continuously. By acquiring the SOC value in real time, it can be used to determine the specific charge level of the lithium battery when an abnormality occurs.

[0096] 202: Change the magnitude of the charging current at any time corresponding to the SOC value, and obtain the response signal during the duration of the charging current change.

[0097] It should be understood that, regardless of whether it is a constant current charging process or a variable current charging process, changing the charging current at any point corresponding to the SOC value can be considered as changing the charging current during a constant current charging process. This constant current charging process can be a segment within a constant current charging process, or a segment within a variable current charging process (i.e., a sub-constant current charging process).

[0098] Changing the current during a constant current charging process is equivalent to applying a disturbance to the stable electrochemical process within a lithium battery. This disturbance will generate multiple response signals (similar to dropping a pebble into calm water). Subsequently, the most sensitive response signal can be selected from these signals to distinguish between lithium batteries undergoing lithium plating and normal batteries. The most sensitive response signal is usually the one with the most significant change.

[0099] Meanwhile, since current disturbance response is fast and easy to control, this application uses the method of changing the charging current to obtain the response signal.

[0100] In one embodiment, the magnitude of the charging current can be changed by outputting a command to change the current at any time corresponding to any SOC value, and the command includes a command to change the magnitude of the charging current and a command to specify the duration of the change in the charging current.

[0101] For example, when this method is applied to, such as Figure 1 When the electric vehicle is connected to the charging station, if the original charging current is I1, the BMS of the electric vehicle outputs a command to the charging station to change the magnitude of the charging current at any time corresponding to the SOC value. The charging station then changes the magnitude (let's say I2) of the charging current output to the lithium battery in the electric vehicle and the duration thereof according to this command, thereby achieving the purpose of changing the charging current. After the duration of the changed charging current, it returns to the charging current before the change; that is, the current is maintained at I2 during the duration, and after the duration, the current returns to I1 from I2.

[0102] For example, suppose this method is applied to test whether lithium batteries are abnormal during the production process, and the charging current of the lithium batteries is provided by a charge / discharge machine. In this case, the control unit in the charge / discharge machine outputs a command to change the current, which is executed by the execution part of the charge / discharge machine, thereby achieving the purpose of changing the charging current.

[0103] It should be understood that although the charging current is changed at any given SOC value, each change in the charging current will last for a period of time, and the corresponding response signal can only be generated within the duration of the change in the charging current.

[0104] like Figure 3a As shown, taking constant current charging as an example, the constant current charging current of the lithium battery is I1A. At times T1A, T3A, and T5A, corresponding to SOC values ​​of 1A%, 2A%, and 3A%, the charging current is changed to I2A. The duration of each current change is abbreviated as (T1A, T2A) from T1A to T2A; (T3A, T4A) from T3A to T4A; and (T5A, T6A) from T5A to T6A. The durations of these three time intervals can be set according to actual usage and can be the same or different; there is no restriction here. For example, the durations of (T1A, T2A), (T3A, T4A), and (T5A, T6A) can all be set to 20 seconds, or to 10 seconds, 20 seconds, and 30 seconds respectively.

[0105] In summary, when the SOC value is 1A%, the charging current changes to I2A at the corresponding time T1A, and the duration of this change is (T1A, T2A). The response signal can be obtained within this time period, and this response signal represents the SOC value at 1A%. Based on the same reasoning, the response signals for SOC values ​​of 2A% and 3A% can be obtained respectively. It can be understood that the charging current I2A is less than the charging current I1A, i.e. Figure 3a The operation shown is to reduce the charging current at any given time corresponding to SOC.

[0106] In other embodiments, the charging current can be increased or the charging current can be made zero, such as... Figure 3b As shown, at times T1B, T3B, and T5B corresponding to SOC values ​​of 1B%, 2B%, and 3B%, the charging current is increased from I1B to I2B, respectively. The implementation process is similar to the process of reducing the charging current, which is easily understood by those skilled in the art and will not be elaborated here.

[0107] 203: Determine whether the lithium battery is abnormal based on the response signals at the corresponding times of multiple SOC values.

[0108] Currently, battery management systems can collect signals such as battery voltage, current, capacity, or temperature.

[0109] Among these factors, the sampling accuracy of capacity and temperature signals is relatively low, and they exhibit a certain degree of lag, making it impossible to distinguish signal changes caused by a small amount of lithium plating. Therefore, capacity and temperature signals are not suitable as response signals. Furthermore, in this application, the response signal is obtained by changing the charging current, making a current signal unsuitable as the response signal. Therefore, this application selects a voltage signal, which has higher accuracy and a faster response, as the response signal. Alternatively, a resistance signal obtained from a voltage signal could also be used as the response signal.

[0110] In summary, the response signal can be either a voltage signal or a resistance signal. Please refer to [link / reference needed]. Figure 4 , Figure 4 This is a schematic diagram of a possible response signal (in this case, a voltage signal), as shown below. Figure 4 As shown, the voltage changes over time to form curve U1, which is the voltage signal. This voltage signal is only the response signal within the duration of a single change in the charging current.

[0111] Specifically, a sampling interval can be preset, and voltage values ​​can be continuously collected at the sampling interval during each change in charging current duration. The collected voltage values ​​constitute the voltage signal.

[0112] If the response signal is a resistance signal, then there are multiple ways to obtain the resistance signal. If the charging process is a constant current charging process, please refer to [the relevant documentation]. Figure 3a Assuming the resistance signal is the response signal between (T1A, T2A), the method to obtain the resistance signal is as follows: (1) Obtain the charging current before the SOC value is 1A%, denoted as I. old Obtain each voltage value in curve U1 and I respectively. old (1) The ratio of the resistance signal to the resistance signal; (2) The charging current during the time period (T1A, T2A) is obtained and denoted as I. new Obtain each voltage value in curve U1 and I respectively. new (3) Obtain the ratio of I to obtain the resistance signal; new with I old The difference between them is denoted as I. new1 Obtain each voltage value in curve U1 and I respectively. new1 The ratio of the two values ​​is used to obtain the resistance signal.

[0113] If the charging process is a variable current charging process, then as mentioned above, when the charging current is changed during a certain sub-constant current charging process of variable current charging, the charging current of that sub-constant current charging process is used as I. old , while I new with I new1 The method for obtaining the voltage signal is similar to that used during constant current charging. Then, multiple voltage signals or multiple resistance signals can be used to determine whether the lithium battery is malfunctioning.

[0114] In one embodiment, at least three response signals are obtained by changing the charging current at at least three times corresponding to at least three SOC values, and the presence or absence of an abnormality in the lithium battery is determined based on these at least three response signals. The specific determination method is illustrated using a voltage signal as an example of the response signal. Figure 5 As shown, the method includes:

[0115] 501: Obtain the first voltage value in the Nth voltage signal at the start time of the first preset duration, and obtain the second voltage value in the Nth voltage signal at the end time of the first preset duration.

[0116] 502: Obtain the Nth voltage change value based on the absolute value of the difference between the first voltage value and the second voltage value in the Nth voltage signal.

[0117] The first preset duration is any time period within the duration range of each change in charging current, in combination with... Figure 3a and Figure 4 The content in the document will be explained. For example... Figure 3a As shown, with at least three SOC values: 1A%, 2A%, 3A%,..., the charging current is changed to I2A, and the corresponding voltage signals are obtained in (T1A, T2A), (T3A, T4A), (T5A, T6A),..., respectively. Therefore, at least three voltage signals are obtained in total. Let's assume the voltage signal obtained in (T1A, T2A) is... Figure 4 The voltage signal U1 in the N is the first voltage signal (N is 1). Then, any time period within (T1A, T2A), such as the duration of time period (T41, T42), can be used as the first preset duration. (T41, T42) lies within (T1A, T2A), meaning T41 >= T1A and T42 <= T2A. T41 is the start time of the first preset duration, and T42 is the end time of the first preset duration. The first voltage value of the voltage signal U1 is obtained as U41, and the second voltage value is U42. The absolute value of the difference between the first voltage value U41 and the second voltage value U42 is calculated as ΔU1 = |U41 - U42| (the absolute value of the difference between U41 and U42). The difference ΔU1 can be considered the first voltage change value. Similarly, the second voltage change value can be obtained from (T3A, T4A), the third voltage change value can be obtained from (T5A, T6A), and so on. If the charging current is changed a total of N times, a total of N voltage change values ​​can be obtained.

[0118] The selection of the first preset duration can be determined based on actual usage, typically ranging from 0.1s to 100s, and is not limited here. In a preferred embodiment, the time period corresponding to the least noisy part of the response signal can be selected as the first preset duration, depending on the battery type and sampling method. That is, before testing, the parameters of the device used to change the charging current are used to determine a relatively stable time range for the test signal, thereby avoiding noise signals and obtaining voltage change values ​​from a more accurate voltage signal to achieve a more accurate final judgment. For example, as... Figure 6 As shown, before time T61, the instability of the current may cause noise signals. Therefore, the first preset duration can be set to be after time T61 in advance to avoid noise signals.

[0119] It should be understood that during multiple changes in charging current, the SOC values ​​between each change can be the same or different. For example, in one embodiment, the charging current is changed every 5% increase in SOC value during charging. Figure 3a In one embodiment, the SOC value increases during the time periods (T2A, T3A) and (T4A, T5A) are both set to 5%; in another embodiment, the SOC value increases during the time period (T2A, T3A) can be set to 5%, and the SOC value increases during the time period (T4A, T5A) can be set to 10%.

[0120] Similarly, the duration of each change in current can be the same or different, still based on... Figure 3a For example, the durations of the three time periods (T1A, T2A), (T3A, T4A), and (T5A, T6A) can be the same or different. However, it is important to note that the first preset duration within each time period must be the same. Figure 3a and Figure 4 For example, assuming that the first preset duration extracted in (T1A,T2A) is the duration of the time period (T41,T42), then in (T3A,T4A) and (T5A,T6A), the corresponding first voltage value, second voltage value and voltage change value need to be obtained within the same first preset duration.

[0121] For example, assuming the durations of the three time periods (T1A, T2A), (T3A, T4A), and (T5A, T6A) are 10 seconds, 12 seconds, and 15 seconds respectively, and the first preset duration is 5 seconds, then it is necessary to extract response signals with a duration of 5 seconds from the 10-second, 12-second, and 15-second intervals respectively. Furthermore, it is optimal that the extracted time period is the same each time. That is, if the time period corresponding to the first preset duration is set to 3-8 seconds within the duration of the charging current change, then the moment of each charging current change should be taken as a relative "0 second" position, and the first voltage value, second voltage value, and voltage change value within the relative "3-8 seconds" time period should be obtained. That is, T1A, T3A, and T5A are all taken as the relative "0 seconds" position. If T1A is 20 seconds, T3A is 50 seconds, and T5A is 100 seconds, then the first voltage change value is obtained within 23-28 seconds, the second voltage change value is obtained within 53-58 seconds, and the third voltage change value is obtained within 103-108 seconds.

[0122] It is understood that the above is the specific implementation process for obtaining multiple voltage change values ​​when the response signal is a voltage signal. If the response signal is a resistance signal, multiple resistance change values ​​can be obtained in the same way. Other details that are easily understood by those skilled in the art will not be elaborated here.

[0123] 503: Determine if the lithium battery is abnormal based on the voltage change value.

[0124] Taking voltage signal as an example, after obtaining the voltage change value, it is possible to directly determine whether the lithium battery is abnormal based on the voltage change value, or to obtain the corresponding resistance change value based on the voltage change value and determine whether the lithium battery is abnormal based on the resistance change value.

[0125] In one implementation, the presence or absence of an abnormality in the lithium battery can be determined directly based on the voltage change value, such as... Figure 7 As shown, the execution process is as follows:

[0126] 701: Obtain the Nth data point based on the Nth voltage change value and its corresponding SOC value.

[0127] 702: Determine if the lithium battery is abnormal based on the data points.

[0128] Again Figure 3a For example, Figure 3aAs shown above, at times T1A, T3A, T3A... corresponding to SOC values ​​of 1A%, 2A%, 3A%..., the charging current is changed to I2A. Therefore, voltage signals can be obtained in (T1A, T2A), (T3A, T4A), (T5A, T6A)..., for a total of N voltage signals. Simultaneously, within a first preset duration of the aforementioned time period, the first voltage value and the second voltage value of each voltage signal are extracted, thus obtaining the voltage change values ​​in each time period (T1A, T2A), (T3A, T4A), (T5A, T6A)..., which are respectively the first voltage change value ΔU1, the second voltage change value ΔU2, the third voltage change value ΔU3... the Nth voltage change value ΔUN.

[0129] Therefore, in one embodiment, each voltage change value and its corresponding SOC value can be considered as a data point, where the SOC value can be the SOC value before each charging current change. For example, the SOC value corresponding to the first voltage change value ΔU1 is 1A%, the SOC value corresponding to the second voltage change value ΔU2 is 2A%, the SOC value corresponding to the third voltage change value ΔU3 is 3A%, and so on, thus obtaining data points such as (1A%, ΔU1), (2A%, ΔU2), (3A%, ΔU3), etc. Based on these data points, it can be determined whether the lithium battery is abnormal.

[0130] Of course, since the duration of each charging current change is relatively short, the change in SOC value within that time period is also small. Therefore, any SOC value within the duration of each charging current change can be used as the SOC value corresponding to each voltage change value. For example, assuming the SOC values ​​at times T2A, T4A, and T6A are 1A1%, 2A1%, and 3A1%, respectively, then the SOC value corresponding to the first voltage change value ΔU1 can be any one of (1A% and 1A1%), the SOC value corresponding to the second voltage change value ΔU2 can be any one of (2A% and 2A1%), the SOC value corresponding to the third voltage change value ΔU3 can be any one of (3A% and 3A1%), and so on. Multiple data points can be obtained, and these data points can be used to determine whether the lithium battery is abnormal.

[0131] It is understandable that the data points obtained will differ depending on the first preset duration setting. For example, in one embodiment, setting the first preset duration to the duration of a time period of (1s, 8s) and setting the first preset duration to the duration of a time period of (3s, 8s) will yield the following results respectively: Figure 8 The curves shown are composed of multiple data points. Based on these multiple data points, it is possible to determine whether the lithium battery is abnormal.

[0132] Furthermore, in another embodiment, after obtaining multiple data points, the slope of adjacent data points can be used to determine whether the lithium battery is abnormal. The specific implementation process is as follows: obtain the Nth slope between the N+1th data point and the Nth data point, and the N+1th slope between the N+2th data point and the N+1th data point. If the Nth slope is greater than 0 and the N+1th slope is less than 0, then the lithium battery is determined to be abnormal.

[0133] like Figure 9a As shown, assuming the charging current is changed at SOC values ​​of 65%, 70%, 75%, 80%, and 85%, the five data points obtained are p1(65%, 23), p2(70%, 24), p3(75%, 25), p4(80%, 23), and p5(85%, 21). The slope between p2 and p1 is K1 (K1 = (24-23) / (70%-60%)), the slope between p3 and p2 is K2, the slope between p4 and p3 is K3, and the slope between p5 and p4 is K4. Then, each pair of adjacent slopes is evaluated. If the first slope of two adjacent slopes is greater than 0 and the second slope is less than 0, an anomaly can be identified. For example, in... Figure 9a In the diagram, K1 and K2 are adjacent slopes, but both K1 and K2 are greater than 0, so no anomaly has occurred yet. Continuing to obtain adjacent slopes K2 and K3, we find that slope K2 is greater than 0 while slope K3 is less than 0. This confirms that the lithium battery has experienced an anomaly, and it can be assumed that the anomaly will occur approximately when the SOC value reaches 75%.

[0134] It should be noted that, in Figure 9a In the illustrated embodiment, the difference between the SOC values ​​corresponding to every two data points is the same, which is 5%. However, in other embodiments, the difference between the SOC values ​​corresponding to every two data points may be different.

[0135] like Figure 9b As shown, in this embodiment, after changing the charging current at times corresponding to SOC values ​​of 65%, 68%, 70%, 75%, 80%, and 85%, the six data points obtained are p11, p21, p31, p41, p51, and p61, respectively. The difference between the SOC values ​​corresponding to data point p31 and data point p21 is 2%, while the difference between the SOC values ​​corresponding to data point p41 and data point p31 is 5%. However, the above-mentioned scheme can also be used to determine whether the lithium battery is abnormal by the slope.

[0136] Meanwhile, when the battery's SOC value changes from 0-100%, the response signal does not decrease first and then increase with the change in SOC value, which may result in the following: Figure 10The response signal shown (in this case, a voltage signal) decreases, increases, decreases again, and increases again, while the battery is not malfunctioning during this process. Therefore, to prevent false positives and improve the accuracy of the judgment, it is generally advisable to judge whether the battery is malfunctioning within a range where the SOC value is greater than 40%, and optimally, within a range where the SOC value is greater than 60%.

[0137] In another embodiment, the Nth resistance change value can be obtained by first obtaining the Nth voltage change value, and the lithium battery can be determined as to whether an abnormality has occurred based on the obtained resistance change value. The above process can also be implemented by various methods.

[0138] Optionally, such as Figure 11 As shown, Figure 11 A possible method for determining whether a lithium battery is malfunctioning based on resistance changes is described, comprising the following steps:

[0139] 1101: Get the first current value of the charging current at any time before each change in the charging current.

[0140] 1102: Calculate the ratio of the Nth voltage change value to the first current value, and record it as the Nth first resistance change value.

[0141] 1103: Obtain the Nth data point based on the Nth first resistance change value and its corresponding SOC value.

[0142] 1104: Determine whether the lithium battery is abnormal based on the data points.

[0143] If it is a constant current charging method, assuming the charging current value is I11, then the first current value of the charging current at any time before each change of the charging current is I11. Then, by directly calculating the ratio of each obtained voltage change value to I11, each first resistance change value can be obtained.

[0144] In the case of variable current charging, as described above, when the charging current is changed during a sub-constant current charging process, assuming the current value of that sub-constant current charging process is I21, the change value of each first resistance can be obtained by calculating the ratio of each obtained voltage change value to I21. After obtaining multiple first resistance change values, the data point can also be obtained by using the Nth first resistance change value and its corresponding SOC value.

[0145] Assuming the data points obtained from the voltage change values ​​are as follows Figure 12a As shown, under constant current charging mode, the data points obtained from the change in the first resistance (ΔR1) are as follows: Figure 12b As shown, under the variable current charging method, the data points obtained from the change in the first resistance (ΔR11) are as follows: Figure 12c As shown in the diagram, after obtaining the data point from the first resistance change value, the Nth slope and the (N+1)th slope can also be obtained from the data point. If the Nth slope is greater than 0 and the (N+1)th slope is less than 0, it can be determined whether the lithium battery is abnormal. The above process is similar to obtaining data points from the voltage change value and its corresponding SOC value, and determining whether the lithium battery is abnormal based on the data points. This is easily understood by those skilled in the art and will not be elaborated further here.

[0146] Optionally, such as Figure 13 As shown, Figure 13 Another possible method for determining whether a lithium battery is malfunctioning based on resistance changes includes the following steps:

[0147] 1301: Obtain the second current value of the charging current at any time within the duration of each change in charging current.

[0148] 1302: Calculate the ratio of the Nth voltage change value to the second current value, and record it as the Nth second resistance change value.

[0149] 1303: Obtain the Nth data point based on the Nth second resistance change value and its corresponding SOC value.

[0150] 1304: Determine whether the lithium battery is abnormal based on the data points.

[0151] In this method, regardless of whether it is constant current charging or variable current charging, the obtained value is the second current value I13 of the charging current at any time within the duration of each current change. By calculating the ratio of each voltage change to I13, each second resistance change value can be obtained. In the variable current charging method, the data points obtained from the second resistance change value (ΔR13) are as follows: Figure 14 As shown.

[0152] Similarly, after obtaining data points from the second resistance change value, the Nth slope and the (N+1)th slope can be obtained from the data points. If the Nth slope is greater than 0 and the (N+1)th slope is less than 0, it is determined whether the lithium battery is abnormal. The above process is similar to obtaining data points based on the voltage change value and its corresponding SOC value, and determining whether the lithium battery is abnormal based on the data points. This is easily understood by those skilled in the art and will not be elaborated further here.

[0153] Optionally, such as Figure 15 As shown, Figure 15 Here is another possible method for determining whether a lithium battery is malfunctioning based on resistance changes. This method includes:

[0154] 1501: Obtain the third current value of the charging current at any time before each change of the charging current, and the fourth current value of the charging current at any time during the duration of each change of the charging current.

[0155] 1502: Calculate the absolute value of the difference between the third current value and the fourth current value.

[0156] 1503: Calculate the ratio of the Nth voltage change value to its absolute value, and record it as the Nth third resistance change value.

[0157] 1504: Obtain the Nth data point based on the Nth change value of the third resistance and its corresponding SOC value.

[0158] 1505: Determine whether the lithium battery is abnormal based on the data points.

[0159] The method for obtaining the third current value is the same as Figure 11 The method for obtaining the first current value is the same; the method for obtaining the fourth current value is the same. Figure 13 The method for obtaining the second current value is the same. Then, the absolute value I15 of the difference between the third and fourth current values ​​can be calculated. By calculating the ratio of each voltage change value to I15, each third resistance change value can be obtained. In the variable current charging mode, the data points obtained from the third resistance change value (ΔR15) are as follows: Figure 16 As shown.

[0160] Similarly, after obtaining the data point from the third resistance change value, the Nth slope and the (N+1)th slope can be obtained from the data point. If the Nth slope is greater than 0 and the (N+1)th slope is less than 0, it is determined whether the lithium battery is abnormal. The above process is similar to obtaining data points from the voltage change value and its corresponding SOC value, and determining whether the lithium battery is abnormal based on the data points. This is easily understood by those skilled in the art and will not be elaborated here.

[0161] It should be understood that the method provided in this application embodiment can be used to determine whether a lithium battery is abnormal, regardless of whether it is a constant current charging method or a variable current charging method. However, it should be noted that for the variable current charging method, the method with the highest detection accuracy and suitable for detecting a small number of abnormalities is as follows: Figure 15 The method shown is the one with the worst accuracy. Figure 13 The method shown.

[0162] In summary, when the response signal is a voltage signal, after obtaining multiple voltage change values, multiple data points can be obtained directly from the voltage change values, and the slope of adjacent data points can be used to determine whether the lithium battery is abnormal. Alternatively, the resistance change value can be obtained from the voltage change value first, then multiple data points can be obtained from the resistance change value, and finally the slope of adjacent data points can be used to determine whether the lithium battery is abnormal.

[0163] If the response signal is a resistance signal, then the resistance signal needs to be obtained from the voltage signal, and then the resistance change value can be obtained directly from the resistance signal. Then, multiple data points can be obtained based on the resistance change value, and the slope of adjacent data points among the multiple data points can be used to determine whether the lithium battery is abnormal.

[0164] In practical applications, constant current charging is used as an example, and the lithium battery is controlled under different charging currents to detect any abnormalities. A 60Ah commercial lithium-ion battery can be selected, with constant current charging rates of 0.3C, 0.5C, and 1.0C. When the battery reaches 5% SOC, the current is changed to 0.1C for 8 seconds. The obtained data points and judgment results are as follows: Figure 17 As shown.

[0165] When the constant current charging rate is 0.3C, the slopes obtained from adjacent data points do not satisfy the condition that the preceding slope is greater than 0 and the following slope is less than 0, indicating that the lithium battery is not malfunctioning. Furthermore, disassembling the lithium battery confirms that it is not malfunctioning, consistent with the judgment result provided by the method in this application embodiment.

[0166] When the constant current charging rate is 0.5C, the slopes obtained from adjacent data points do not satisfy the condition that the preceding slope is greater than 0 and the following slope is less than 0, indicating that the lithium battery is not malfunctioning. Furthermore, disassembly of the lithium battery confirms that it is not malfunctioning.

[0167] When the constant current charging rate is 1.0C, based on the slopes obtained from adjacent data points, near the SOC value of 80%, there appears to be a situation where the preceding slope is greater than 0 and the following slope is less than 0, indicating that the lithium battery has malfunctioned. Furthermore, disassembly of the lithium battery confirms that it has indeed malfunctioned, consistent with the judgment result of the method provided in the embodiments of this application.

[0168] In summary, regardless of the initial constant current charging current, the presence or absence of an abnormality in the lithium battery can be determined by changing the charging current during the charging process.

[0169] In another embodiment, also using constant current charging as an example, and maintaining a charging rate of 1.2C, the charging current is reduced to 0 (i.e., left to stand), and the current is increased (or decreased) by 1.1C and 1.0C, respectively, to detect whether the lithium battery is abnormal. Specifically, the charging current is changed once every 5% of the battery's SOC value, and the duration is 8 seconds. The obtained data points and judgment results are as follows. Figure 18 As shown.

[0170] The added pulse refers to the process of changing the current magnitude, which can be approximated as adding a pulse to the original charging current. For example, adding an 8-second pause reduces the current to 0 and maintains this for 8 seconds. This is equivalent to adding a current pulse of the same magnitude but opposite direction to the original charging current, thus achieving an actual charging current of 0 during those 8 seconds. Figure 18 It can be seen that in the above three cases, when the SOC value is around 80%, the first slope of the adjacent slopes is greater than 0 and the second slope is less than 0, indicating that the lithium battery has malfunctioned. Furthermore, disassembly of the lithium battery confirmed that it had indeed malfunctioned, consistent with the judgment result of the judgment method provided in the embodiments of this application.

[0171] Therefore, the method for detecting lithium battery abnormalities provided in this application embodiment can be achieved by either increasing the charging current of the lithium battery or decreasing the charging current of the lithium battery.

[0172] In another embodiment, taking constant current charging as an example, and maintaining a charging rate of 1.5C, when the battery's SOC value is increased by 5%, the current is increased (or decreased) by 1.4C for a duration of 8 seconds. Different data points can be obtained by selecting different first preset durations. The obtained data points and judgment results are as follows: Figure 19 As shown.

[0173] The first preset duration is set to 3 seconds, 8 seconds, and 5 seconds respectively. Figure 19 It can be seen that in the above three cases, when the SOC value is around 70%, the first slope of the adjacent slopes is greater than 0 and the second slope is less than 0, indicating that the lithium battery has malfunctioned. Furthermore, disassembly of the lithium battery confirmed that it had indeed malfunctioned, consistent with the judgment result of the judgment method provided in the embodiments of this application.

[0174] Therefore, the first preset duration and its starting point can both be set according to the user's actual usage, and both can determine whether the lithium battery is abnormal.

[0175] Figure 20 This is a schematic diagram of a device for detecting abnormalities in lithium batteries provided in an embodiment of this application. Figure 20As shown, the lithium battery anomaly detection device 2000 includes a first acquisition unit 2001, a second acquisition unit 2002, and a determination unit 2003. The first acquisition unit 2001 acquires the State of Charge (SOC) value of the lithium battery during charging, where the SOC value is the ratio of the remaining battery capacity to the battery's nominal capacity. The second acquisition unit 2002 changes the charging current at any given SOC value and acquires the response signal during the duration of the current change. The determination unit 2003 determines whether the lithium battery is abnormal based on the response signals at multiple SOC value times.

[0176] Since the device embodiments and method embodiments are based on the same concept, the content of the device embodiments can refer to the method embodiments, provided that the content does not conflict with each other, and will not be repeated here.

[0177] Figure 21 This is a schematic diagram of the structure of a device for detecting abnormalities in a lithium battery, provided in an embodiment of this application. Figure 21 As shown, the device 2100 for detecting lithium battery abnormalities includes one or more processors 2101 and a memory 2102. Wherein, Figure 21 Take a processor 2101 as an example.

[0178] The processor 2101 and the memory 2102 can be connected via a bus or other means. Figure 21 Taking the example of a connection between China and Israel via a bus.

[0179] The memory 2102, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as the program instructions / modules corresponding to the method for detecting lithium battery abnormalities in the embodiments of this application (e.g., attached...). Figure 20 (The aforementioned units). The processor 2101 executes various functional applications and data processing of the lithium battery anomaly detection device by running non-volatile software programs, instructions, and modules stored in the memory 2102, thereby realizing the method for detecting lithium battery anomalies in the above method embodiments and the functions of the various modules and units in the above device embodiments.

[0180] Memory 2102 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 2102 may optionally include memory remotely located relative to processor 2101, and such remote memory may be connected to processor 2101 via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0181] The program instructions / modules are stored in the memory 2102. When executed by one or more processors 2101, they perform the method for detecting lithium battery abnormalities in any of the above method embodiments, for example, performing the above-described method. Figure 2 , Figure 5 , Figure 7 , Figure 11 , Figure 13 and Figure 15 The steps shown can also be implemented in the appendix. Figure 20 The functions of each of the aforementioned units.

[0182] This application also provides a battery management system, including the device for detecting lithium battery abnormalities as described in any of the above embodiments. The battery management system can be installed in vehicles, etc., and can manage the battery.

[0183] This application also provides a battery system, including a rechargeable battery and a battery management system as described in any of the above embodiments, the battery management system being used to manage the battery.

[0184] This application also provides an electric vehicle, including a charging and discharging device and a battery system as described in any of the above embodiments. The charging and discharging device can be used to charge the battery, while the battery management system in the battery system can control the magnitude of the charging current used by the charging and discharging device to charge the battery.

[0185] This application also provides a non-volatile computer storage medium storing computer-executable instructions that are executed by one or more processors, for example... Figure 21 One of the processors, 2101, can enable the one or more processors to execute the method for detecting lithium battery abnormalities in any of the above method embodiments. For example, it can execute the method for detecting lithium battery abnormalities in any of the above method embodiments, such as the method described above. Figure 2 , Figure 5 , Figure 7 , Figure 11 , Figure 13 and Figure 15 The steps shown can also be implemented in the appendix. Figure 20 The functions of each of the aforementioned units.

[0186] The device or equipment embodiments described above are merely illustrative. The unit modules described as separate components may or may not be physically separate. The components shown as module units may or may not be physical units; that is, they may be located in one place or distributed across multiple network module units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0187] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0188] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for detecting abnormalities in lithium batteries, comprising: The SOC value during the charging process of the lithium battery is obtained, wherein the SOC value is the ratio of the remaining battery capacity to the nominal battery capacity; The charging current is changed at any time corresponding to the SOC value, and the response signal is obtained during the duration of the charging current change. The lithium battery is determined to be abnormal based on the response signals at the corresponding times of the multiple SOC values; The response signal is a voltage signal; Determining whether the lithium battery is abnormal based on the response signals corresponding to multiple SOC values ​​at different times includes: Obtain the first voltage value in the Nth voltage signal at the start of the first preset duration, and obtain the second voltage value in the Nth voltage signal at the end of the first preset duration, wherein the first preset duration is any time period within the duration of each change in charging current; The Nth voltage change value is obtained by the absolute value of the difference between the first voltage value and the second voltage value in the Nth voltage signal; Determine whether the lithium battery is malfunctioning based on the voltage change value; The step of determining whether the lithium battery is abnormal based on the voltage change value includes: The Nth data point is obtained based on the Nth voltage change value and its corresponding SOC value; Based on the data points, determine whether the lithium battery is abnormal; or, Get the first current value of the charging current at any time before each change in the charging current; Calculate the ratio of the Nth voltage change value to the first current value, and record it as the Nth first resistance change value; Based on the Nth first resistance change value and its corresponding SOC value, obtain the Nth data point; Based on the data points, determine whether the lithium battery is abnormal; or, Obtain the third current value of the charging current at any time before each change of the charging current, and the fourth current value of the charging current at any time during the duration of each change of the charging current. Calculate the absolute value of the difference between the third current value and the fourth current value; Calculate the ratio of the Nth voltage change value to the absolute value, and record it as the Nth third resistance change value; The Nth data point is obtained based on the Nth change value of the third resistance and its corresponding SOC value; Based on the data points, determine whether the lithium battery is malfunctioning.

2. The method according to claim 1, wherein, Changing the magnitude of the charging current at any given time corresponding to the SOC value includes: At any given time corresponding to the SOC value, an instruction to change the current is output to change the magnitude of the charging current, wherein the instruction to change the current includes an instruction to change the magnitude of the charging current and an instruction to specify the duration of the change in the charging current.

3. The method according to claim 1, wherein, Changing the magnitude of the charging current at any given time corresponding to the SOC value includes: The magnitude of the charging current is changed at at least three times corresponding to the SOC value.

4. The method according to any one of claims 1-3, wherein, The step of determining whether the lithium battery is abnormal based on the data points includes: Obtain the Nth slope between the (N+1)th data point and the Nth data point, and the (N+1)th slope between the (N+2)th data point and the (N+1)th data point; If the slope of the Nth digit is greater than 0 and the slope of the (N+1)th digit is less than 0, then the lithium battery is determined to be abnormal.

5. A device for detecting abnormalities in lithium batteries, comprising: The first acquisition unit is used to acquire the SOC value during the charging process of the lithium battery, wherein the SOC value is the ratio of the remaining battery capacity to the nominal battery capacity. The second acquisition unit is used to change the magnitude of the charging current at any time corresponding to the SOC value, and acquire the response signal within the duration of the change in the charging current. The determining unit is used to determine whether the lithium battery is abnormal based on the response signals at the corresponding times of the multiple SOC values; The response signal is a voltage signal; The determining unit is specifically used for: Obtain the first voltage value in the Nth voltage signal at the start of the first preset duration, and obtain the second voltage value in the Nth voltage signal at the end of the first preset duration, wherein the first preset duration is any time period within the duration of each change in charging current; The Nth voltage change value is obtained by the absolute value of the difference between the first voltage value and the second voltage value in the Nth voltage signal; Determine whether the lithium battery is malfunctioning based on the voltage change value; The determining unit determines whether the lithium battery is abnormal based on the voltage change value, including: The Nth data point is obtained based on the Nth voltage change value and its corresponding SOC value; Based on the data points, determine whether the lithium battery is abnormal; or, Get the first current value of the charging current at any time before each change in the charging current; Calculate the ratio of the Nth voltage change value to the first current value, and record it as the Nth first resistance change value; Based on the Nth first resistance change value and its corresponding SOC value, obtain the Nth data point; Based on the data points, determine whether the lithium battery is abnormal; or, Obtain the third current value of the charging current at any time before each change of the charging current, and the fourth current value of the charging current at any time during the duration of each change of the charging current. Calculate the absolute value of the difference between the third current value and the fourth current value; Calculate the ratio of the Nth voltage change value to the absolute value, and record it as the Nth third resistance change value; The Nth data point is obtained based on the Nth change value of the third resistance and its corresponding SOC value; Based on the data points, determine whether the lithium battery is malfunctioning.

6. A device for detecting abnormalities in lithium batteries, comprising: Memory; And a processor coupled to the memory, the processor being configured to perform the method as described in any one of claims 1 to 4 based on instructions stored in the memory.

7. A battery management system, comprising: The apparatus for detecting lithium battery malfunctions as described in claim 5 or 6.

8. A battery system, comprising: A rechargeable battery and a battery management system as described in claim 7.

9. An electric vehicle, comprising: The charging and discharging equipment and the battery system as described in claim 8.

10. A computer-readable storage medium comprising: The device stores computer-executable instructions configured as a method flow as described in any one of claims 1 to 4.

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