Battery cell testing method and apparatus, and method for acquiring SOH prediction model

Abstract

Provided in the embodiments of the present application are a battery cell testing method and apparatus, and a method for acquiring an SOH prediction model. The testing method comprises: acquiring information on a current and time of a battery cell in a target stage, wherein the target stage comprises a stage in which the current decreases during a target constant-voltage charging process after a charging cut-off voltage is reached or a stage in which the current decreases during a target constant-voltage discharging process after a discharging cut-off voltage is reached; on the basis of the information on the current and time in the target stage, determining a slope value of a current-time function relationship in the target stage; and on the basis of the slope value, testing the battery cell. By means of the battery cell testing method and apparatus and the method for acquiring an SOH prediction model provided in the embodiments of the present application, the accuracy of battery cell testing can be improved.

Description

Methods and devices for detecting individual battery cells, and methods for obtaining SOH prediction models. Cross-reference to related applications

[0001] This application claims priority to Chinese Patent Application No. 202510191698.8, filed on February 20, 2025, entitled “Method for detecting a single battery cell, method and apparatus for obtaining a SOH prediction model”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery testing technology, and more specifically, to a method and apparatus for testing a single battery cell, and a method and apparatus for obtaining a SOH prediction model. Background Technology

[0003] During battery production and use, batteries need to be tested to determine whether they meet production requirements and user needs. For example, during the use of lithium-ion batteries, with the increase in charge-discharge cycles, individual battery cells undergo irreversible aging, resulting in irreversible side reactions such as the production of gases like carbon monoxide and hydrogen, causing the battery cells to swell. When the internal pressure of the battery cell increases to a certain level, some parts of the battery cell, such as welds, may break, leading to electrolyte leakage and affecting battery performance and lifespan.

[0004] Therefore, how to accurately test individual battery cells during the production and use of batteries is one of the urgent problems to be solved. Summary of the Invention

[0005] This application provides a method and apparatus for detecting battery cells, and a method and apparatus for obtaining a SOH prediction model, which can accurately detect battery cells.

[0006] Firstly, a method for detecting a single battery cell is provided. The method includes: acquiring information on the current and time of the single battery cell in a target stage, where the target stage includes a current decrease during a target constant-voltage charging process after reaching the charging cutoff voltage or a current decrease during a target constant-voltage discharging process after reaching the discharging cutoff voltage; determining the slope value of the current-time function relationship in the target stage based on the current and time information of the single battery cell in the target stage; and detecting the single battery cell based on the slope value.

[0007] In this embodiment, the slope of the current-time function relationship in the target phase can be determined based on the information of the current and time during the current decrease phase of the battery cell during the target constant voltage charging process or the information of the current and time during the current decrease phase of the battery cell during the target constant voltage discharging process. The battery cell can then be detected based on this slope, which can improve the accuracy of battery cell detection. At the same time, it is not necessary to disassemble the battery device (such as the battery pack) and battery cells, which facilitates the detection of battery cells.

[0008] In one possible implementation, based on the current and time information of the battery cell in the target stage, the slope of the current-time function relationship in the target stage is determined, including: using the current in the target stage as the ordinate, and... The target line is obtained as the horizontal axis, and the slope value of the target line is determined, where t is the time of the target stage.

[0009] In this embodiment, the current and time of a battery cell during the current decrease phase of the target constant voltage charging process or the current and time of a battery cell during the current decrease phase of the target constant voltage discharging process can be used to determine the current as the vertical axis and the current as the horizontal axis. The slope value of the target line used as the horizontal axis is used to detect individual battery cells, which can improve the accuracy of individual battery cell detection. At the same time, it does not require disassembling the battery device (such as the battery pack) and individual battery cells, making it convenient to detect whether the individual battery cells are broken.

[0010] In one possible implementation, the battery cell is detected based on the slope value, including determining whether the battery cell is broken based on the change in the slope value.

[0011] In this embodiment of the application, by acquiring the current and time information of the battery cell at multiple target stages, it is convenient to determine multiple slope values ​​of multiple target lines corresponding to the battery cell at multiple target stages. Then, based on the changing trend of multiple slope values, the battery cell can be accurately detected to determine whether the battery cell is broken, without the need to disassemble the battery device (such as the battery pack) and the battery cell, which facilitates the detection of whether the battery cell is broken.

[0012] In one possible implementation, obtaining information on the current and time of a single battery cell in a target phase includes: obtaining information on the current and time of a single battery cell in multiple target phases, wherein the multiple target phases respectively include a phase in which the current decreases during multiple target constant voltage charging processes or multiple target constant voltage discharging processes.

[0013] In this embodiment of the application, by acquiring the current and time information of the battery cell at multiple target stages, it is convenient to determine multiple slope values ​​of multiple target lines corresponding to the battery cell at multiple target stages. Then, based on the changing trend of multiple slope values, the battery cell can be accurately detected to determine whether the battery cell is broken, without disassembling the battery device (such as battery pack) and the battery cell, which facilitates the detection of the battery cell.

[0014] In one possible implementation, the current at the target stage is used as the vertical axis, and... The target line is obtained by using the current at multiple target stages as the horizontal axis, and the slope value of the target line is determined, including: using the current at multiple target stages as the vertical axis, and the slope value corresponding to the multiple target stages. As the horizontal axis, multiple target lines are obtained, and multiple slope values ​​of the multiple target lines are determined.

[0015] In this embodiment of the application, by determining multiple slope values ​​of multiple target lines corresponding to multiple target stages of a single battery cell, the change trend of multiple slope values ​​can be used to determine whether the battery cell is broken. This can improve the accuracy of battery cell detection, and at the same time, it does not require disassembly of the battery device (such as a battery pack) and the battery cell, making it convenient to detect whether the battery cell is broken.

[0016] In one possible implementation, determining whether a battery cell has ruptured based on changes in slope values ​​includes: determining that a battery cell has ruptured when the changing trend of multiple slope values ​​is downward and the degree of decline is greater than or equal to a preset degree.

[0017] In the embodiments of this application, when the slope values ​​of a battery cell decrease significantly at multiple target stages, it can be determined that the battery cell has broken, thereby improving the accuracy of detecting whether a battery cell has broken.

[0018] In one possible implementation, the multiple target stages include the 1st, nth, and n+1th target stages. The 1st, nth, and n+1th target stages include the current decrease phases during the 1st, nth, and n+1th target constant-voltage charging processes. Based on the change in the slope value, it is determined whether a single battery cell has broken, including: In the case where it is determined that the battery cell breaks in the (n+1)th target stage, K n K represents the slope value of a single battery cell in the nth target stage. n+1 K is the slope value of the battery cell in the (n+1)th target stage, K1 is the slope value of the battery cell in the 1st target stage, and K 预设 This is the default value.

[0019] In this embodiment of the application, by With K预设 By comparing the size relationships, the determination of battery cell rupture can be made, which can improve the accuracy of detecting whether a battery cell is ruptured.

[0020] In one possible implementation, K 预设 ≥20%.

[0021] In this embodiment of the application, by using K 预设 A value of ≥20% can reduce the impact of data fluctuations on the test results and accurately detect whether the outer structure of a battery cell is broken.

[0022] In one possible implementation, the battery cell is tested based on the slope value, including: determining the SOH value of the battery cell based on the slope value.

[0023] In this embodiment, the SOH value of a battery cell can be determined based on the slope value of the target line corresponding to the target stage, thereby improving the accuracy of SOH detection. Furthermore, SOH detection can be performed during the charging and discharging process of a battery cell, simplifying the SOH detection operation.

[0024] In one possible implementation, determining the SOH value of a battery cell based on the slope value includes: determining the SOH value of a battery cell based on the slope value and an SOH prediction model, wherein the SOH prediction model includes a correspondence between multiple slope values ​​and multiple SOH values.

[0025] In the embodiments of this application, the SOH value of a battery cell can be accurately determined by using the slope value of the target line of the battery cell at the target stage and the SOH prediction model.

[0026] In one possible implementation, the target phase includes the phase after the current decreases during the target constant voltage charging process, 100 seconds later, and t=0 corresponds to the moment when the current begins to decrease during the target constant voltage charging process.

[0027] In this embodiment of the application, the target line determined by the current and time after the current drops for 100 seconds during the target constant voltage discharge process is closer to a straight line. By using the slope value of this target line that is close to a straight line, the battery cell can be detected more accurately.

[0028] In one possible implementation, the target phase includes the period between 150s and 1000s during the current drop in the target constant voltage charging process.

[0029] In this embodiment, by selecting the target stage between 150s and 1000s during the current drop in the target constant voltage charging process, the determined target line is closer to a straight line. Using the slope value of this near-straight target line, the individual battery cells can be detected more accurately. Furthermore, the amount of data in the target stage can be significantly reduced, thus minimizing data overhead.

[0030] Secondly, a method for obtaining a State of Health (SOH) prediction model is provided. This method includes: determining first information, which includes multiple SOH values ​​corresponding to multiple charge-discharge cycles of a single battery cell, wherein the multiple charge-discharge cycles satisfy at least one of the following conditions: multiple charging cycles include multiple charging to the charging cutoff voltage and multiple target constant-voltage charging after reaching the charging cutoff voltage; multiple discharging cycles include multiple discharging to the discharging cutoff voltage and multiple target constant-voltage discharging after reaching the discharging cutoff voltage; obtaining second information, which includes current and time information of the single battery cell in multiple target stages, wherein the multiple target stages include stages of current decrease during multiple target constant-voltage charging or stages of current decrease during multiple target constant-voltage discharging; determining multiple slope values ​​corresponding to the current-time function relationship of the multiple target stages based on the current and time information of the single battery cell in the multiple target stages; and establishing an SOH prediction model based on the multiple SOH values ​​and multiple slope values ​​corresponding to the multiple charge-discharge cycles.

[0031] In this embodiment of the application, an SOH prediction model can be established based on multiple SOH values ​​corresponding to multiple charge-discharge cycles of a battery cell and multiple slope values ​​of multiple current-time functional relationships determined by current and time information of multiple target stages. Thus, the SOH of the battery cell can be accurately detected by using the slope value of the target line determined during the use of the battery cell and the SOH prediction model.

[0032] In one possible implementation, based on the current and time information of the battery cell at multiple target stages, multiple slopes of multiple current-time functional relationships corresponding to multiple target stages are determined, including: using the current at multiple target stages as the ordinate, and using the current at multiple target stages as the ordinate, and the slopes of multiple slopes corresponding to the current at multiple target stages as the slopes. As the horizontal axis, multiple target lines are obtained, and multiple slope values ​​of multiple target lines are determined, where t is the time corresponding to each of the multiple target stages.

[0033] In this embodiment, an SOH prediction model can be established based on the slope value of the target line determined by multiple SOH values ​​corresponding to multiple charge-discharge cycles of a battery cell and current and time information of multiple target stages. Thus, the SOH of the battery cell can be accurately detected by using the slope value of the target line determined during the use of the battery cell and the SOH prediction model.

[0034] In one possible implementation, the multiple target stages each include the stage after the current decreases during multiple target constant voltage charging processes, and t=0 corresponds to the moment when the current begins to decrease during the target constant voltage charging process.

[0035] In the embodiments of this application, the target line determined by the current and time after the current drops for 100 seconds during the target constant voltage charging process is close to a straight line. The SOH prediction model obtained by the slope value of this target line that is close to a straight line can accurately determine the SOH of the battery cell.

[0036] In one possible implementation, the multiple target stages each include a phase between the 150th and 1000th seconds of current decrease during multiple target constant voltage charging processes.

[0037] In this embodiment, by selecting the target stage between 150s and 1000s during the current drop in the target constant voltage charging process, the determined target line is closer to a straight line. Using the slope value of this near-straight target line, the resulting SOH prediction model can accurately determine the SOH of a single battery cell. Furthermore, this significantly reduces the amount of data required for the target stage, thereby reducing data overhead.

[0038] In one possible implementation, before determining the first information and acquiring the second information, the method further includes performing multiple charge-discharge cycles on a single battery cell.

[0039] In the embodiments of this application, by performing multiple charge-discharge cycles on a single battery cell, it is easy to obtain multiple SOH values ​​of the battery cell in multiple charge-discharge cycles, as well as information on the current and time of the battery cell in multiple target stages, thereby facilitating the establishment of an SOH prediction model for the battery cell.

[0040] In one possible implementation, the battery cell is subjected to multiple charge-discharge cycles, including: performing multiple charge-discharge cycles on the battery cell to bring the battery cell to the end-of-life (EOL) state.

[0041] In this embodiment of the application, by performing multiple charge-discharge cycles on a single battery cell to reach the end-of-life (EOL) state, the first and second information of the battery cell throughout its entire lifespan can be obtained to establish a state-of-the-art (SOH) prediction model for the battery cell from charge-discharge cycle to EOL state, thereby enabling the detection of SOH of the battery cell in the EOL state.

[0042] In one possible implementation, before determining the first information, the method further includes: obtaining the SOH evaluation parameters of the battery cell during multiple charge-discharge cycles; determining the first information includes: determining the first information based on the SOH evaluation parameters.

[0043] In the embodiments of this application, the SOH value of a battery cell after multiple charge-discharge cycles can be accurately determined by the SOH evaluation parameter of the battery cell, thereby obtaining an accurate SOH prediction model for the battery cell.

[0044] Thirdly, a detection device for a single battery cell is provided. The detection device includes: an acquisition unit for acquiring information on the current and time of the single battery cell in a target stage, the target stage including a stage of current decrease during target constant voltage charging after reaching the charging cutoff voltage or a stage of current decrease during target constant voltage discharging after reaching the discharging cutoff voltage; a processing unit for determining the slope value of the current-time function relationship in the target stage based on the information on the current and time of the single battery cell in the target stage; and a device for detecting the single battery cell based on the slope value.

[0045] In one possible implementation, the processing unit is configured to use the current of the plurality of target stages as the ordinate and the current corresponding to the plurality of target stages as the coordinates. Using the x-axis as the horizontal axis, multiple target lines are obtained, and multiple slope values ​​of the multiple target lines are determined, where t is the time corresponding to each of the multiple target stages.

[0046] In one possible implementation, a processing unit is used to determine whether a single battery cell has broken based on changes in the slope value.

[0047] In one possible implementation, an acquisition unit is used to acquire current and time information of a single battery cell in multiple target stages, including a current-decreasing stage during multiple target constant-voltage charging processes or multiple target constant-voltage discharging processes.

[0048] In one possible implementation, the processing unit is configured to use the current of multiple target stages as the ordinate and the current corresponding to the multiple target stages as the coordinates. As the horizontal axis, multiple target lines are obtained, and multiple slope values ​​of the multiple target lines are determined.

[0049] In one possible implementation, the processing unit is used to determine that a battery cell is broken when the changing trend of multiple slope values ​​is downward and the degree of decline is greater than or equal to a preset degree.

[0050] In one possible implementation, the multiple target stages include a 1st, nth, and n+1th target stage. The 1st, nth, and n+1th target stages include the current decrease phases during the 1st, nth, and n+1th target constant-voltage charging processes. The processing unit is used to... In the case where it is determined that the battery cell breaks in the (n+1)th target stage, Kn K represents the slope value of a single battery cell in the nth target stage. n+1 K is the slope value of the battery cell in the (n+1)th target stage, K1 is the slope value of the battery cell in the 1st target stage, and K 预设 This is the default value.

[0051] In one possible implementation, K 预设 ≥20%.

[0052] In one possible implementation, a processing unit is used to determine the SOH value of a single cell based on the slope value.

[0053] In one possible implementation, a processing unit is used to determine the SOH value of a battery cell based on the slope value and the SOH prediction model, wherein the SOH prediction model includes a correspondence between multiple slope values ​​and multiple SOH values.

[0054] In one possible implementation, the target stage includes the stage after the current decreases during the target constant voltage charging process or the target constant voltage discharging process, and t=0 corresponds to the moment when the current begins to decrease during the target constant voltage charging process or the target constant voltage discharging process.

[0055] In one possible implementation, the target phase includes the period between 150s and 1000s during the target constant voltage charging process or the target constant voltage discharging process when the current drops.

[0056] Fourthly, an apparatus for obtaining a SOH prediction model is provided. The apparatus includes: a processing unit for determining first information, the first information including multiple SOH values ​​corresponding to multiple charge-discharge cycles of a battery cell, wherein the multiple charge-discharge cycles satisfy at least one of the following conditions: multiple charging in the multiple charge-discharge cycles includes multiple charging to the charging cutoff voltage and multiple target constant-voltage charging after multiple charging to the charging cutoff voltage; multiple discharging in the multiple charge-discharge cycles includes multiple discharging to the discharging cutoff voltage and multiple target constant-voltage discharging after multiple discharging to the discharging cutoff voltage; an acquisition unit for acquiring second information, the second information including current and time information of the battery cell in multiple target stages, the multiple target stages including stages of current decrease during multiple target constant-voltage charging after multiple charging to the charging cutoff voltage or stages of current decrease during multiple target constant-voltage discharging after multiple discharging to the discharging cutoff voltage; a processing unit for determining multiple slope values ​​of multiple current-time corresponding functions in the multiple target stages based on the current and time information of the battery cell in the multiple target stages; and for establishing an SOH prediction model based on the multiple SOH values ​​and multiple slope values ​​corresponding to the multiple charge-discharge cycles.

[0057] In one possible implementation, the multiple target stages each include a stage after the current decreases 100s during multiple target constant voltage charging processes or multiple target constant voltage discharging processes, and t=0 corresponds to the moment when the current begins to decrease during the target constant voltage charging process or the target constant voltage discharging process.

[0058] In one possible implementation, the multiple target stages respectively include the stage between the 150th and 1000th seconds of the current drop during multiple target constant voltage charging processes or multiple target constant voltage discharging processes.

[0059] In one possible implementation, a processing unit is used to perform multiple charge-discharge cycles on individual battery cells.

[0060] In one possible implementation, a processing unit is used to perform multiple charge-discharge cycles on a single battery cell to bring the battery cell to the end-of-life (EOL) state.

[0061] In one possible implementation, an acquisition unit is used to acquire the SOH evaluation parameters of a single battery cell during multiple charge-discharge cycles; and a processing unit is used to determine first information based on the SOH evaluation parameters.

[0062] Fifthly, a detection device for a single battery cell is provided, the detection device comprising a memory and a processor, the memory for storing instructions, and the processor for reading the instructions and executing a detection method as described in the first aspect and any possible implementation thereof.

[0063] In a sixth aspect, an apparatus for obtaining a SOH prediction model is provided, the apparatus comprising a memory and a processor, the memory for storing instructions, and the processor for reading the instructions and executing, according to the instructions, a method as described in the second aspect and any possible implementation thereof.

[0064] In a seventh aspect, a computer-readable storage medium is provided for storing a computer program that, when executed by a computer, causes the computer to implement the method as described in any possible implementation of the first or second aspect.

[0065] Eighthly, a computer program product is provided, including computer program instructions that, when executed by a computer, cause the computer to implement the method as in any possible implementation of the first or second aspect. Attached Figure Description

[0066] Figure 1 is a flowchart illustrating the detection method for a single battery cell provided in an embodiment of this application.

[0067] Figure 2 is a schematic diagram of the current change during the constant voltage charging process provided in this application.

[0068] Figure 3 is a schematic diagram of the current change during the current decrease stage in the constant voltage charging process provided in the embodiment of this application.

[0069] Figure 4 shows the current at the target stage provided in the embodiments of this application. A diagram illustrating the relationship between the two.

[0070] Figure 5 is a flowchart illustrating the detection method for a single battery cell provided in an embodiment of this application.

[0071] Figure 6 is a flowchart illustrating the detection method for a single battery cell provided in an embodiment of this application.

[0072] Figure 7 is a schematic diagram of the SOH prediction model provided in the embodiments of this application.

[0073] Figure 8 is a flowchart illustrating the detection method for a single battery cell provided in an embodiment of this application.

[0074] Figure 9 is a flowchart illustrating the method for obtaining the SOH prediction model provided in an embodiment of this application.

[0075] Figure 10 is a schematic diagram of the current change during a constant voltage charging process in a single charge-discharge cycle provided in an embodiment of this application.

[0076] Figure 11 is a schematic diagram of the current change during a constant voltage charging process in a single charge-discharge cycle provided in an embodiment of this application.

[0077] Figure 12 is a schematic diagram showing the relationship between the current and the target stage of a single charge-discharge cycle provided in an embodiment of this application.

[0078] Figure 13 is a flowchart illustrating the method for obtaining the SOH prediction model provided in an embodiment of this application.

[0079] Figure 14 is a flowchart illustrating the method for obtaining the SOH prediction model provided in an embodiment of this application.

[0080] Figure 15 is a schematic block diagram of a battery cell detection device provided in an embodiment of this application.

[0081] Figure 16 is another schematic block diagram of the battery cell detection device provided in the embodiments of this application.

[0082] Figure 17 is a schematic block diagram of the apparatus for obtaining a SOH prediction model provided in an embodiment of this application.

[0083] Figure 18 is another schematic block diagram of the apparatus for obtaining a SOH prediction model provided in an embodiment of this application. Detailed Implementation

[0084] 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.

[0085] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means two or more, unless otherwise explicitly defined. The terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing description of the drawings of this application, are intended to cover non-exclusive inclusion.

[0086] The term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Additionally, the character " / " in this text generally indicates that the preceding and following related objects have an "or" relationship.

[0087] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0088] In this application, the terms "upper," "lower," "left," "right," "inner," and "outer," indicating orientation or positional relationships, are used only for the convenience of describing this application and for 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 of this application. "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.

[0089] 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.

[0090] During battery production and use, batteries need to be tested to determine whether they meet production requirements and user needs. For example, during the use of lithium-ion batteries, with the increase in charge-discharge cycles, individual battery cells undergo irreversible aging, resulting in irreversible side reactions such as the production of gases like carbon monoxide and hydrogen, causing the battery cells to swell. When the internal pressure of the battery cell increases to a certain level, some parts of the battery cell, such as welds, may break, leading to electrolyte leakage and affecting battery performance and lifespan.

[0091] Therefore, how to accurately test individual battery cells during the production and use of batteries is one of the urgent problems to be solved.

[0092] To address the aforementioned issues, embodiments of this application provide a method and apparatus for detecting individual battery cells, and a method and apparatus for obtaining a state of health (SOH) prediction model.

[0093] The detection method includes: acquiring information on the current and time of a single battery cell in a target stage, the target stage including the current decrease during the target constant voltage charging process after reaching the charging cutoff voltage or the current decrease during the target constant voltage discharging process after reaching the discharging cutoff voltage; determining the slope value of the current-time function relationship in the target stage based on the current and time information in the target stage; and detecting the single battery cell based on the slope value.

[0094] The battery cell detection method and apparatus provided in this application can determine the slope value of the current-time function relationship in the target stage based on the current and time information of the battery cell during the current decrease phase of the target constant voltage charging process or the target constant voltage discharging process, and then detect the battery cell based on the slope. This can improve the accuracy of battery cell detection and also realize non-destructive testing of battery cells.

[0095] The method for obtaining the SOH prediction model includes: determining first information, which includes multiple SOH values ​​corresponding to multiple charge-discharge cycles of a battery cell, wherein the multiple charge-discharge cycles satisfy at least one of the following conditions: multiple charging in the multiple charge-discharge cycles includes multiple charging to the charging cutoff voltage and multiple target constant-voltage charging after multiple charging to the charging cutoff voltage; multiple discharging in the multiple charge-discharge cycles includes multiple discharging to the discharging cutoff voltage and multiple discharging to the discharging cutoff voltage and multiple target constant-voltage discharging after multiple discharging; obtaining second information, which includes current and time information of the battery cell in multiple target stages, wherein the multiple target stages include stages of current decrease during multiple target constant-voltage charging or stages of current decrease during multiple target constant-voltage discharging; determining multiple slope values ​​corresponding to the current-time function relationship of the multiple target stages based on the current and time information of the multiple target stages; and establishing an SOH prediction model based on the multiple SOH values ​​and multiple slope values ​​corresponding to the multiple charge-discharge cycles.

[0096] The method for obtaining a SOH prediction model provided in this application embodiment can establish an SOH prediction model based on multiple SOH values ​​corresponding to multiple charge-discharge cycles of a battery cell and multiple slope values ​​of multiple current-time functional relationships determined by current and time information of multiple target stages. Thus, the SOH of a battery cell can be accurately detected by using the slope value of the target line determined during the use of the battery cell and the SOH prediction model.

[0097] In this embodiment, the battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrode plates. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the uncoated positive current collector protrudes beyond the coated positive current collector, serving as the positive electrode tab. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the uncoated negative current collector protrudes beyond the coated negative current collector, serving as the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, etc. To ensure that a large current can pass through without melting, there are multiple positive electrode tabs stacked together, and there are multiple negative electrode tabs stacked together. The separator can be made of PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to these.

[0098] First, the battery cell detection method provided in the embodiments of this application will be described by way of example with reference to Figures 1 to 8.

[0099] Figure 1 is a flowchart illustrating the detection method for a single battery cell provided in an embodiment of this application.

[0100] 110, Obtain information on the current and time of individual battery cells during the target stage.

[0101] The target stage includes the current decrease stage during the target constant voltage charging process after reaching the charging cutoff voltage or the current decrease stage during the target constant voltage discharging process after reaching the discharging cutoff voltage.

[0102] The charging cutoff voltage refers to the maximum voltage that a battery is allowed to reach during charging.

[0103] The discharge cutoff voltage refers to the minimum voltage that a battery is allowed to reach during discharge.

[0104] The information on the current and time of a single battery cell in the target stage can be the information on the charging current and time during the charging current decrease phase of the battery cell in the target constant voltage charging process when the charging cutoff voltage is reached, or the information on the discharge current and time during the discharge current decrease phase of the battery cell in the target constant voltage discharging process when the discharge cutoff voltage is reached.

[0105] The target constant-voltage charging process can be a constant-voltage charging process where a single battery cell is charged to the charging cutoff voltage and then discharged at a constant voltage. The target constant-voltage discharging process can be a constant-voltage discharging process where a single battery cell is discharged to the discharging cutoff voltage and then discharged at a constant voltage. As an example, the target constant-voltage charging process can be a continuous charging process. As another example, the target constant-voltage discharging process can be a continuous discharging process.

[0106] The process of target constant voltage charging or target constant voltage discharging may include a phase of current decrease. During the current decrease phase, the current decreases over time.

[0107] As an example, individual battery cells can be charged in various ways, such as constant voltage charging and constant current constant voltage charging.

[0108] For example, when a battery cell is charged using a constant-voltage charging method, the charging voltage is constant while the current gradually decreases. The target constant-voltage charging process after reaching the charging cutoff voltage can be considered as the charging process where the battery cell voltage reaches the charging cutoff voltage during constant-voltage charging. The target stage can also be the stage after the battery cell voltage reaches the charging cutoff voltage during constant-voltage charging.

[0109] For example, when a battery cell is charged using a constant current / constant voltage charging method, in the constant current charging phase, the battery cell is charged with a constant current. When the voltage of the battery cell reaches the charging cutoff voltage, it enters the constant voltage charging phase, where the battery cell is charged with a constant voltage and the current gradually decreases. The process of reaching the target constant voltage charging cutoff voltage can be considered the constant voltage charging phase in a constant current / constant voltage charging method. The target phase can also be considered the constant voltage charging phase in a constant current / constant voltage charging method.

[0110] However, generally speaking, during constant-voltage charging of a battery cell (which can be constant-voltage charging or constant-current / constant-voltage charging), due to the presence of polarization such as ohmic polarization, electrochemical polarization, and concentration polarization, as shown in Figure 2, constant-voltage charging can include two sub-stages: In the first sub-stage of constant-voltage charging, due to the presence of electrochemical polarization and concentration polarization within the battery cell, the constant-voltage charging current remains at its upper limit of allowable current; subsequently, in the second sub-stage of constant-voltage charging, the current gradually decreases. As an example, in this case, the stage where the current gradually decreases (the second sub-stage) can be considered the target stage. Alternatively, the portion of the stage where the current gradually decreases as shown in Figure 2 can also be considered the target stage.

[0111] As an example, by taking the moment when the current drops in Figure 2 as time 0, we can obtain the information on the change of current in a single battery cell over time during the target stage, as shown in Figure 3.

[0112] Of course, the trend of current change during the phase of current decrease in the constant voltage discharge process when the battery cell reaches the target discharge cutoff voltage is similar to the phase of current decrease during the target constant voltage charging process described above.

[0113] As an example, individual battery cells can also be discharged in various ways, such as constant voltage discharge and constant voltage discharge with cross current.

[0114] As an example, when a battery cell discharges using a constant-voltage discharge method, the discharge voltage is constant while the current gradually decreases. The constant-voltage discharge process that reaches the target discharge cutoff voltage can be considered as the discharge process after the voltage of the battery cell reaches the discharge cutoff voltage during the constant-voltage discharge process. The target stage can also be considered as the discharge process after the voltage of the battery cell reaches the discharge cutoff voltage during the constant-voltage discharge process.

[0115] As an example, when a battery cell is discharged using a constant current and constant voltage discharge method, in the constant current discharge stage, the battery cell discharges with a constant current. When the voltage of the battery cell reaches the discharge cutoff voltage, it enters the constant voltage discharge stage, where the battery cell discharges with a constant voltage and the current gradually decreases. The process of reaching the target constant voltage discharge cutoff voltage can be considered the discharge process of the constant voltage discharge stage in a constant current and constant voltage discharge method. The target stage can also be considered the constant voltage discharge stage in a constant current and constant voltage discharge method.

[0116] It should be understood that the current and time information of a single battery cell in the target stage can be in the form shown in Figure 3, or in numerical form, or in other forms. This application does not limit the form in which the current and time information is presented.

[0117] 120. Based on the current and time information of the battery cells in the target stage, determine the slope value of the current-time function relationship in the target stage.

[0118] The current-time function relationship in the target stage can be expressed as a function of m(I)-n(t), where m(I) is a function related to the current I in the target stage, and n(t) is a parameter related to the time t in the target stage. That is, the horizontal axis of this function relationship can be either m(I) or n(t), and the vertical axis can be either m(I) or n(t).

[0119] For example, the current-time function relationship for this target stage can be: The functional relationship, whose ordinate can be... The x-axis of this function can be 1 / I.

[0120] As an example, the current-time function relationship of a target stage can be obtained as a curve, and the slope value of the fitted curve can be used as the slope value of the current-time function relationship of the target stage.

[0121] As another example, the current-time function of a target stage can be represented by a straight line. The slope of this line can be used as the slope of the current-time function of the target stage.

[0122] Generally speaking, based on the information of current and time during the current-time decrease phase in a target constant voltage charging process, or based on the information of current and time during the current-time decrease phase in a target constant voltage discharging process, a slope value corresponding to a current-time function relationship can be obtained.

[0123] 130. Based on the slope value, the individual battery cells are tested.

[0124] In this embodiment, the slope of the current-time function relationship in the target phase can be determined based on the information of the current and time during the current-time decrease phase of the battery cell during the target constant voltage charging process or the information of the current and time during the current-time decrease phase of the battery cell during the target constant voltage discharging process. The battery cell can then be detected based on this slope, which can improve the accuracy of battery cell detection. At the same time, it can achieve non-destructive testing of battery cells without disassembling the battery device (such as the battery pack) and battery cells.

[0125] In some embodiments, the current-time function of the target stage can be expressed as I- The functional relationship.

[0126] That is, in this application, the current at the target stage can be used as the vertical axis, and the horizontal axis can be used as the vertical axis. The target line is obtained by using it as the horizontal axis, and the slope value of the target line is determined.

[0127] t represents the time of the target phase.

[0128] As an example, the vertical axis of the target line can be the current during the current decrease phase of the target's constant voltage charging process, and the horizontal axis can be... t represents the time of the current decrease phase during the constant-voltage charging process. Alternatively, the vertical axis of the target line can be the current during the current decrease phase during the constant-voltage discharging process, and the horizontal axis can be... t represents the time of the current decrease phase during the target constant voltage discharge process.

[0129] As an example, the target line can be a curve. The slope value of the fitted curve can be used as the slope value of the target line. For example, by processing the curve of current changing with time in the target stage shown in Figure 3, the current in the target stage shown in Figure 4 is obtained. The functional relationship is shown in Figure 4. The vertical axis of the target line represents the current during the constant voltage charging process of the target, and the horizontal axis represents the current. t represents the time it takes for the current to decrease during the target constant voltage charging process. The slope of the fitted curve shown in Figure 4 can be used as the slope value of the target line.

[0130] As another example, the target line can also be a straight line. The slope value of this straight line can be used as the slope value of the target line. For example, the straight line could be one with the current at the target stage as the vertical axis and the horizontal axis as the vertical axis. The fitted straight line is obtained by using it as the x-axis.

[0131] Generally speaking, based on the information of current and time during the current decrease phase in a target constant voltage charging process, or based on the information of current and time during the current decrease phase in a target constant voltage discharging process, a slope value corresponding to a target line can be obtained.

[0132] In some embodiments, before obtaining information on the current and time of a single battery cell in the target phase, it is also necessary to determine the starting point of the target phase, i.e., the starting point of the current decrease phase during the target constant voltage charging process or the starting point of the current decrease phase during the target constant voltage discharging process.

[0133] As an example, as mentioned above, the constant current and constant voltage charging method includes a constant current charging stage with a constant current and a constant voltage charging stage with a decreasing current. Here, the time starting point of the constant voltage charging stage can be used as the time starting point of the target stage.

[0134] As an example, as described above, constant voltage charging in constant voltage charging or constant current constant voltage charging can include a first sub-stage of charging at an allowable upper current limit (constant current) and a second sub-stage of current decrease. Here, the starting point of the second sub-stage can be used as the time starting point of the target stage.

[0135] For example, it can be found in I c -I c+1 ≥I 预设 In this case, the time of the Cth current sampling during the target constant voltage charging or discharge process of the battery cell is taken as the starting point of the second stage. c I represents the C-th current sampled from a single battery cell during the target constant-voltage charging or discharging process. c+1 I is the current sampled for the (C+1)th time during the target constant voltage charging or discharging process of a single battery cell. 预设 This is the preset current.

[0136] For example, it can be in I T -I T+ΔT ≥I 预设In this case, the time T during the target constant voltage charging or discharge process of a single battery cell is taken as the starting point of the second stage, t=0. T I represents the current at time T of a single battery cell during the target constant-voltage charging or discharging process. T+ΔT I represents the current of a single battery cell at time T+1 during the target constant voltage charging or discharging process, where ΔT is the time interval between two consecutive current samplings. 预设 This is the preset current.

[0137] As shown in Figure 2, during the target constant voltage charging process, the current begins to decrease around 1350s. Therefore, 1350s in Figure 2 can be taken as the starting point of the target stage (i.e., time 0), thus obtaining the current and time information of the current decrease stage during the target constant voltage charging process shown in Figure 3.

[0138] The method for determining the starting point of the current decrease phase during the target constant voltage discharge process is similar to the method for determining the starting point of the current decrease phase during the target constant voltage charging process, and will not be described in detail here for the sake of brevity.

[0139] In some embodiments, I 预设 ≥0.001C, where C is the capacity of a single battery cell. The unit of C is Ah, I 预设 The unit is A.

[0140] In some embodiments, 0.01C ≥ I 预设 ≥0.001C.

[0141] For example, the capacity of a single hard-shell battery cell is 50Ah, I 预设 It can be 0.5A. For example, the capacity of a single soft-pack battery cell is 3Ah, I... 预设 It can be 0.004A.

[0142] In some embodiments, during the target constant voltage charging or target constant voltage discharging process, the current sampling time interval is ≤10s.

[0143] In some embodiments, during the target constant voltage charging process or the target constant voltage discharging process, the current sampling time interval ranges from 0.1s to 1s.

[0144] In some embodiments, it can be determined whether a battery cell has broken based on the change in the slope value of the battery cell at multiple target stages.

[0145] In some embodiments, the SOH value of a battery cell is determined based on the slope value of the battery cell at the target stage.

[0146] The following description, in conjunction with Figures 5 and 6, provides an exemplary illustration of how this application provides methods for determining whether a battery cell is ruptured and for determining the SOH value of a battery cell.

[0147] Figure 5 is a flowchart illustrating the detection method for determining whether a battery cell is ruptured, as provided in an embodiment of this application.

[0148] 510, obtain information on the current and time of individual battery cells at multiple target stages.

[0149] Multiple target stages include the current decrease stage during multiple target constant voltage charging processes or multiple target constant voltage discharging processes.

[0150] The description of information such as current and time in the target stage can be found in the relevant content in step 110, and will not be repeated here.

[0151] In some embodiments, the multiple target stages can be all the target stages experienced by a single battery cell, i.e., all the number of target constant voltage charging processes or all the number of target constant voltage discharging processes; or they can be a portion of the target stages experienced by a single battery cell.

[0152] In some embodiments, information on the current and time of a single battery cell in each of all target phases can be obtained.

[0153] As an example, information on the current and time of the current drop phase during each target constant voltage charging process of a battery cell can be obtained. Alternatively, information on the current and time of the current drop phase during each target constant voltage discharging process of a battery cell can be obtained.

[0154] As an example, information on the current and time of a single battery cell in the Nth target stage can be obtained, as well as information on the current and time of a single battery cell in the N+1th target stage.

[0155] For example, information on the current and time of the current decrease phase during the Nth target constant voltage charging process can be obtained separately, as well as information on the current and time of the current decrease phase during the N+1th target constant voltage charging process.

[0156] Alternatively, information on the current and time of the current decrease phase during the Nth target constant voltage discharge process can be obtained separately, as well as information on the current and time of the current decrease phase during the N+1th target constant voltage discharge process.

[0157] In this embodiment of the application, by acquiring the current and time information of the battery cell at multiple target stages, it is convenient to determine multiple slope values ​​of multiple target lines corresponding to the battery cell at multiple target stages. Then, based on the changing trend of multiple slope values, the battery cell can be accurately detected to determine whether the battery cell is broken, without the need to disassemble the battery device (such as the battery pack) and the battery cell, which facilitates the detection of whether the battery cell is broken.

[0158] 520, with the current at multiple target stages as the vertical axis and the current corresponding to multiple target stages as the horizontal axis. As the horizontal axis, multiple target lines are obtained, and multiple slope values ​​of the multiple target lines are determined.

[0159] t represents the time of the target phase.

[0160] That is, in this embodiment, the current of each target stage among multiple target stages is used as the vertical axis, and the current corresponding to each target stage is... Using the x-axis as the horizontal axis, obtain the target line corresponding to each target stage, and then determine the slope value of the target line.

[0161] Using the current of a target stage as the ordinate, and the current corresponding to that target stage as the axis... Using the x-axis to obtain a target line, and then determining the slope value of the target line, can be referred to the description above, which will not be repeated here.

[0162] As an example, the current of a single battery cell during the current decrease phase in the Nth target constant voltage charging process can be used as an example. Using the vertical and horizontal axes as the ordinate and the horizontal axis, the target line corresponding to the Nth target stage is obtained, and the slope value of the target line corresponding to the Nth target stage is determined; and using the current and time of the current drop stage during the N+1th target constant voltage charging process of the battery cell as the ordinate and the horizontal axis, the target line corresponding to the N+1th target stage is obtained, and the slope value of the target line corresponding to the N+1th target stage is determined.

[0163] Alternatively, the current during the current decrease phase of the battery cell in the Nth target constant voltage discharge process can be used as the sum of the currents. Using the vertical and horizontal axes as the ordinate and the horizontal axis, the target line corresponding to the Nth target stage is obtained, and the slope value of the target line corresponding to the Nth target stage is determined; and using the current and time of the current drop stage during the N+1th target constant voltage discharge of the battery cell as the ordinate and the horizontal axis, the target line corresponding to the N+1th target stage is obtained, and the slope value of the target line corresponding to the N+1th target stage is determined.

[0164] In this embodiment of the application, by determining multiple slope values ​​of multiple target lines corresponding to multiple target stages of a single battery cell, the change trend of multiple slope values ​​can be used to determine whether the battery cell is broken, thereby improving the accuracy of battery cell detection. At the same time, it is possible to achieve non-destructive testing of battery cells without disassembling the battery device (such as a battery pack) and the battery cells.

[0165] 530. When the changing trend of multiple slope values ​​is downward and the degree of decline is greater than the preset degree, it is determined that the battery cell is broken.

[0166] A battery cell rupture can be understood as the rupture of the outer structure that protects and seals the internal components of the battery cell, such as the electrolyte, electrodes, and circuitry. For example, a battery cell rupture could refer to the rupture of the battery cell's casing and / or a mechanism on the casing that provides sealing and protection for the internal components, such as a pressure relief mechanism.

[0167] In some embodiments, if the slope values ​​corresponding to the two target stages show a downward trend and the degree of decline is large, it is determined that the battery cell is broken.

[0168] As an example, if the slope value corresponding to the (N+1)th target stage is less than the slope value corresponding to the Nth target stage, and the absolute value of the difference between the two is greater than or equal to a preset reduction amount, then a battery cell is determined to have ruptured. For instance, if the slope value corresponding to the current decrease stage during the (N+1)th target constant voltage charging process is less than the slope value corresponding to the current decrease stage during the Nth target constant voltage charging process, and the absolute value of the difference between the two is greater than or equal to a preset reduction amount, then a battery cell is determined to have ruptured. Alternatively, if the absolute value of the difference between the slope value corresponding to the current decrease stage during the (N+1)th target constant voltage discharging process and the slope value corresponding to the current decrease stage during the Nth target constant voltage discharging process is greater than or equal to a preset reduction amount, then a battery cell is determined to have ruptured.

[0169] In the embodiments of this application, when the slope values ​​of a battery cell decrease significantly at multiple target stages, it can be determined that the battery cell has broken, thereby improving the accuracy of detecting whether a battery cell has broken.

[0170] In some embodiments, the multiple target stages may include a first, nth, and n+1th target stage, wherein the first, nth, and n+1th target stages include the current decrease phase during the first, nth, and n+1th target constant voltage charging processes, or the first, nth, and n+1th target stages include the current decrease phase during the first, nth, and n+1th target constant voltage discharging processes. In this case, it is determined that the battery cell breaks in the (n+1)th target stage.

[0171] Among them, Kn K represents the slope value of the target line corresponding to the battery cell in the nth target stage. n+1 Let K1 be the slope value of the target line corresponding to the battery cell in the (n+1)th target stage, and K1 be the slope value of the target line corresponding to the battery cell in the 1st target stage. 预设 This is the default value.

[0172] For example, based on the current and time information during the current decrease phases of the 1st, nth, and n+1th target constant voltage charging processes, three slope values ​​for the three target lines corresponding to the current decrease phases during the 1st, nth, and n+1th target constant voltage charging processes can be determined. Then, based on these three slope values, the degree of slope reduction can be determined, thereby determining whether the battery cell has cracked.

[0173] Alternatively, based on the current and time information during the current-decreasing phases of the 1st, nth, and n+1th target constant-voltage discharge processes, the three slope values ​​of the three target lines corresponding to the current-decreasing phases during the 1st, nth, and n+1th target constant-voltage discharge processes can be determined. Then, based on these three slope values, the degree of slope reduction can be determined, thereby determining whether the battery cell has broken.

[0174] In this embodiment of the application, by With K 预设 By comparing the size relationships, it can be determined whether a battery cell is broken, which can improve the accuracy of detecting whether a battery cell is broken.

[0175] In some embodiments, K 预设 ≥20%.

[0176] For example, in In this case, it is determined that the battery cell breaks in the (n+1)th target stage.

[0177] In this embodiment of the application, by using K 预设 A value of ≥20% can reduce the impact of data fluctuations on the test results and accurately detect whether the outer structure of a battery cell is broken.

[0178] Figure 6 is a flowchart illustrating the detection method for determining the SOH value of a battery cell provided in an embodiment of this application.

[0179] 610, Obtain information on the current and time of individual battery cells during the target stage.

[0180] The target stage includes the current decrease during the target constant voltage charging process after reaching the charging cutoff voltage, or the target stage includes the current decrease during the target constant voltage discharging process after reaching the discharging cutoff voltage.

[0181] 620, with the target stage current as the vertical axis and the horizontal axis as the vertical axis. The target line is obtained by using it as the horizontal axis, and the slope value of the target line is determined.

[0182] t represents the time of the target phase.

[0183] The contents of steps 610 and 620 can be found in the descriptions of steps 110 and 120, and will not be repeated here.

[0184] 630. Based on the slope value, determine the SOH value of the battery cell.

[0185] There is a correlation between the slope value and the SOH of a single battery cell; therefore, the SOH value of a single battery cell can be determined based on the slope value.

[0186] For example, the formula relating the slope value and the state of harmonics (SOH) of a single battery cell is: K = a(1-SOH) + b. Here, K is the slope value, and SOH is the SOH value of the single battery cell. The SOH value of a single battery cell can be calculated using this formula.

[0187] In this embodiment, the SOH value of a battery cell can be determined based on the slope value of the target line corresponding to the target stage, thereby improving the accuracy of SOH detection. Furthermore, SOH detection can be performed during the charging and discharging process of a battery cell, simplifying the SOH detection operation.

[0188] In some embodiments, the SOH value of a battery cell can be determined based on the slope value of the target line corresponding to the battery cell at the target stage and the SOH prediction model, wherein the SOH prediction model includes the correspondence between multiple slope values ​​and multiple SOH values.

[0189] SOH prediction models can include machine learning models, correspondence formulas, correspondence tables, or correspondence graphs.

[0190] Figure 7 shows the SOH prediction model in the form of a correspondence diagram. Based on the slope value determined in step 620 and the SOH prediction model shown in Figure 7, the SOH value of the battery cell can be determined.

[0191] In the embodiments of this application, the SOH value of a battery cell can be accurately determined by using the slope value of the target line of the battery cell at the target stage and the SOH prediction model.

[0192] In some embodiments, the target stage includes the stage after the current decreases during the target constant voltage charging process, 100 seconds later, and t=0 corresponds to the moment when the current begins to decrease during the target constant voltage charging process.

[0193] Alternatively, the target phase includes the phase after the current decreases during the target constant voltage discharge process, 100 seconds later, and t=0 corresponds to the moment when the current begins to decrease during the target constant voltage discharge process.

[0194] The stage after the current drops by 100s, i.e., t≥100s, corresponds to For example, the interval after the 100th second of the charging current decrease in Figure 3 corresponds to the interval in Figure 4. The range.

[0195] As can be seen from Figure 4, Within the interval, the current follows The trend of change is close to a straight line, that is, the target line is close to a straight line, and the slope value of the target line can be determined more accurately.

[0196] As an example, information on the current and time after the 100th second of the current drop in a single battery cell during multiple target constant voltage charging processes can be obtained. Then, based on the current and time information after the 100th second corresponding to each of the multiple target constant voltage charging processes, multiple slope values ​​of multiple target lines can be determined to detect whether a single battery cell is broken.

[0197] As an example, information on the current and time after the current drop 100 seconds during the Mth target constant voltage charging process can be obtained to determine the slope value corresponding to the Mth target stage, and the battery cells can be detected to determine the SOH of the battery cells.

[0198] In the embodiments of this application, the target line determined by the current and time after the current drops for 100 seconds during the target constant voltage discharge process, or the current and time after the current drops for 100 seconds during the target constant voltage discharge process, is closer to a straight line. By using the slope value of this target line that is close to a straight line, the battery cell can be detected more accurately.

[0199] In some embodiments, the target phase includes the phase after the current decreases during the target constant voltage charging process at 150 seconds, and t=0 corresponds to the moment when the current begins to decrease during the target constant voltage charging process.

[0200] The stage after the current drops by 150s, i.e., t≥150s, corresponds to Approximately ≤0.082. As can be seen from Figure 4, in... Within the range of approximately 0.08, the target line is closer to a straight line, thus allowing for a more accurate determination of the slope value of the target line.

[0201] In the embodiments of this application, the target line determined by the current and time after the current drops for 150 seconds during the target constant voltage discharge process, or the current and time after the current drops for 150 seconds during the target constant voltage discharge process, is closer to a straight line. By using the slope value of this target line that is close to a straight line, the battery cell can be detected more accurately.

[0202] On the other hand, the current and time after the current drops 150 seconds during the target constant voltage discharge process, or the current and time after the current drops 150 seconds during the target constant voltage discharge process, greatly reduce the amount of data when detecting individual battery cells, thus reducing data overhead.

[0203] In some embodiments, the target phase includes a phase during the target constant voltage charging process where the current decreases between 150s and 1000s or during the target constant voltage discharging process where the current decreases between 150s and 1000s.

[0204] In this embodiment, by selecting the target stage between 150s and 1000s during the current drop in the target constant voltage charging or discharging process, the determined target line is made closer to a straight line. The slope value of this near-straight target line allows for more accurate detection of individual battery cells. Furthermore, this significantly reduces the amount of data required for the target stage, thereby minimizing data overhead.

[0205] Figure 8 is a flowchart illustrating the detection method for a single battery cell provided in an embodiment of this application.

[0206] 810. Perform constant voltage charging on battery cells that have reached the charging cutoff voltage, or perform constant voltage discharging on battery cells that have reached the discharging cutoff voltage.

[0207] The constant voltage charging in step 810 includes the target constant voltage charging.

[0208] The constant voltage discharge in step 810 includes the target constant voltage discharge.

[0209] The details of charging cutoff voltage, target constant voltage charging, discharging cutoff voltage, and target constant voltage discharging can be found in the relevant descriptions above, and will not be repeated here.

[0210] In some embodiments, battery cells that have reached preset conditions multiple times may be subjected to multiple constant-voltage charging, each of which includes multiple target constant-voltage charging; or battery cells that have reached discharge cutoff voltage multiple times may be subjected to multiple constant-voltage discharging, each of which includes multiple target constant-voltage discharging, in order to detect whether the battery cells are ruptured.

[0211] In some embodiments, the battery cell that reaches the charging cutoff voltage for the Mth time may be subjected to the Mth constant voltage discharge, the Mth constant voltage charge including the Mth target constant voltage charge, or the battery cell that reaches the discharge cutoff voltage for the Mth time may be subjected to the Mth constant voltage discharge, the Mth constant voltage discharge including the Mth target constant voltage discharge, in order to determine the SOH value of the battery cell.

[0212] In the embodiments of this application, by performing constant voltage charging on battery cells that have reached the charging cutoff voltage, or by performing constant voltage discharging on battery cells that have reached the discharging cutoff voltage, it is convenient to obtain information on the current and time of the battery cells during the target constant voltage charging process, or information on the current and time of the battery cells during the target constant voltage discharging process, that is, it is convenient to obtain information on the current and time of the battery cells at the target stage.

[0213] In some embodiments, constant voltage charging of a battery cell that has reached the charging cutoff voltage includes: charging the battery cell to the charging cutoff current of the battery cell.

[0214] In the embodiments of this application, by charging the individual battery cells at a constant voltage to the charging cutoff current, it is convenient to control the termination of charging of the individual battery cells.

[0215] Optionally, constant voltage charging is performed on the battery cells that have reached the charging cutoff voltage, including: constant voltage charging of the battery cells to charge them to any point before the charging cutoff current of the battery cells.

[0216] For example, a single battery cell can be charged to the 1000th second of the current drop phase of the target constant voltage charging.

[0217] In some embodiments, the charging cutoff current of a single battery cell is ≤0.05C.

[0218] In some embodiments, the charging cutoff current of a single battery cell ranges from 0.01C to 0.05C.

[0219] In some embodiments, the upper limit of the current for constant voltage charging is in the range of 0.5C to 1C.

[0220] In some embodiments, the upper limit of the current for constant voltage charging ranges from 0.7C to 1C.

[0221] In some embodiments, constant voltage discharge is performed on a battery cell that has reached the discharge cutoff voltage, including: performing constant voltage discharge on the battery cell to discharge to the discharge cutoff current of the battery cell.

[0222] In the embodiments of this application, by discharging the battery cell at a constant voltage to the discharge cutoff current, it is convenient to control the termination of the discharge of the battery cell.

[0223] Optionally, the target constant voltage discharge is performed on the battery cell that has reached the discharge cutoff voltage, including: performing constant voltage discharge on the battery cell to discharge to any time before the discharge cutoff current of the battery cell.

[0224] The battery cell can be discharged until the current drops 1000 seconds into the constant voltage discharge process, and then the discharge can be terminated.

[0225] 820, obtain information on the current and time of individual battery cells at the target stage.

[0226] The target phase includes the current decrease phase during the target constant voltage charging process after reaching the charging cutoff voltage and the current decrease phase during the target constant voltage discharging process after reaching the discharging cutoff voltage.

[0227] 830, with the target stage current as the vertical axis and the horizontal axis as the vertical axis. The target line is obtained by using it as the horizontal axis, and the slope value of the target line is determined.

[0228] t represents the time of the target phase.

[0229] 840. Based on the slope value, the individual battery cells are tested.

[0230] The contents of steps 820 to 840 can be referred to the relevant descriptions in Figures 1 to 7, and will not be repeated here.

[0231] In some embodiments, the battery cells may be charged with constant current before constant voltage charging is performed on the battery cells that have reached the charging cutoff voltage.

[0232] As an example, a single battery cell can be charged at a constant current to its charging cutoff voltage, and then charged at a constant voltage; or, a single battery cell can be charged at a constant current first, then charged at a constant voltage to its charging cutoff voltage, and then charged at a constant voltage.

[0233] Constant current charging can take different forms. For example, it can be performed by charging individual battery cells at a constant charging rate or by performing constant current charging in a gradient manner.

[0234] Gradient constant current charging can also be called segmented constant current charging. That is, constant current charging is divided into multiple stages, and each stage is charged with a constant current. The currents in the multiple stages are different, such as the currents in the multiple stages showing a gradually decreasing trend.

[0235] In this embodiment of the application, constant current charging of the battery cells before target constant voltage charging can improve charging efficiency, reduce charging time, and reduce the time required to detect battery cells, thereby improving user experience.

[0236] In some embodiments, before performing constant current charging on a single battery cell, the detection method further includes discharging the single battery cell.

[0237] As an example, the discharge of a single battery cell can occur during its normal use, such as when the battery cell supplies power to an electrical device. For instance, a battery cell may discharge and then recharge during use, and the charging method could be a constant current, constant voltage charging method.

[0238] Optionally, the battery cells can be charged with constant voltage before the battery cells that have reached the charging cutoff voltage are charged with constant voltage.

[0239] That is, the battery cells are charged at a constant voltage both before and after they reach the charging cutoff voltage.

[0240] In some embodiments, the battery cells may be subjected to constant current discharge before constant voltage discharge is performed on the battery cells that have reached the discharge cutoff voltage.

[0241] As an example, a constant current and constant voltage discharge can be performed on a single battery cell. The battery cell can be discharged at a constant current until its discharge cutoff voltage, and then discharged at a constant voltage; alternatively, the battery cell can be first discharged at a constant current, then discharged at a constant voltage until its discharge cutoff voltage, and then discharged at a constant voltage.

[0242] Constant current discharge can take different forms. For example, it can be performed by constant current discharge of a single battery cell at a constant discharge rate, or it can be performed by constant current discharge of a single battery cell in a gradient constant current discharge manner.

[0243] In this embodiment of the application, by performing constant current discharge on the battery cells, the discharge efficiency can be improved, the loss of battery performance and lifespan can be reduced, and the time required to detect the battery cells can be reduced, thereby improving the user experience.

[0244] Optionally, the battery cells can be subjected to constant voltage discharge before the battery cells that have reached the discharge cutoff voltage are subjected to constant voltage discharge.

[0245] That is, the battery cells are subjected to constant voltage discharge both before and after they reach the discharge cutoff voltage.

[0246] In some embodiments, the detection method further includes charging the battery cell before performing constant current discharge on the battery cell.

[0247] As an example, constant current discharge of a battery cell can refer to the discharge of the battery cell during normal use, while charging of a battery cell can refer to the charging of the battery cell at a charging station after use.

[0248] The following describes the method for obtaining the SOH prediction model with reference to Figures 9 to 13.

[0249] Figure 9 is a flowchart illustrating the method for obtaining the SOH prediction model provided in an embodiment of this application.

[0250] 910, confirm the first piece of information.

[0251] The first piece of information includes multiple SOH values ​​corresponding to multiple charge-discharge cycles of a single battery cell.

[0252] Multiple charge-discharge cycles satisfy at least one of the following conditions: multiple charging in multiple charge-discharge cycles includes multiple charging to the charging cutoff voltage and multiple charging to the charging cutoff voltage followed by multiple target constant voltage charging; multiple discharging in multiple charge-discharge cycles includes multiple discharging to the discharging cutoff voltage and multiple discharging to the discharging cutoff voltage followed by multiple target constant voltage discharging.

[0253] In multiple charge-discharge cycles, each charge must be charged to the charging cutoff voltage and then constant voltage charging is performed; and / or, in multiple charge-discharge cycles, each discharge must be discharged to the discharge cutoff voltage and then constant voltage discharging is performed.

[0254] As an example, multiple charge-discharge cycles of a single battery cell can be a charge-discharge cycle in which the battery cell is charged from 30% to 100% and then discharged back to 30%.

[0255] As an example, multiple charge-discharge cycles of a single battery cell can be a charge-discharge cycle in which the battery cell is discharged from 60% capacity to 0% and then recharged to 60% capacity.

[0256] As an example, multiple charge-discharge cycles of a single battery cell can be defined as a charge-discharge cycle consisting of 100% full charge and 100% full discharge. That is, a full charge is charging the battery from 0% to 100%, and a full discharge is discharging the battery from 100% to 0%.

[0257] In this embodiment, the battery cell's charge level is 100%, which can be the charge level when the battery cell is charged to the charging cutoff voltage; or, it can be the charge level after charging to the charging cutoff voltage and the target constant voltage discharge. Similarly, the battery cell's charge level is 0%, which can be the charge level when the battery cell is discharged to the discharge cutoff voltage; or, it can be the charge level after discharging to the discharge cutoff voltage and the target constant voltage discharge.

[0258] The state of harmonics (SOH) of a battery cell changes during charge-discharge cycles. Generally, the SOH of a battery cell gradually decreases as the number of charge-discharge cycles increases. For example, the SOH of a battery cell can be determined based on its charge-discharge capacity over multiple charge-discharge cycles.

[0259] 920, obtain the second information.

[0260] The second information includes the current and time information of the battery cells in multiple target stages, which include the current decrease stage during multiple target constant voltage charging processes or the current decrease stage during multiple target constant voltage discharging processes.

[0261] The target stage is illustrated below with reference to Figures 10 and 11. The current variation trend over time in Figures 10 and 11 is similar to that in Figures 2 and 3.

[0262] A single charge-discharge cycle in a multi-charge-discharge cycle includes one charge and one discharge. One charge includes a target phase, namely, a process of charging to the charging cutoff voltage and then a target constant-voltage charging process after reaching the charging cutoff voltage, the target constant-voltage charging process including a current decrease phase. Alternatively, one discharge includes a target phase, namely, a process of discharging to the discharging cutoff voltage and then a target constant-voltage discharging process after reaching the discharging cutoff voltage, the target constant-voltage discharging process including a current decrease phase.

[0263] In other words, a target stage is the stage of current decrease during the target constant voltage charging process after the battery cell reaches the charging cutoff voltage during a single charge; or a target stage is the stage of current decrease during the target constant voltage discharging process after the battery cell voltage reaches the discharging cutoff voltage during a single discharge.

[0264] In the embodiments of this application, a single charge or discharge can be a continuous process or a discontinuous process.

[0265] The charging cutoff voltage refers to the maximum voltage that a single battery cell can reach during charging.

[0266] The discharge cutoff voltage refers to the minimum voltage that a single battery cell is allowed to reach when it discharges.

[0267] Information on the current and time of a single battery cell at multiple target stages can be information on the current and time during the current decrease phase of a single battery cell during multiple target constant-voltage charging processes after reaching the charging cutoff voltage multiple times, or information on the current and time during the current decrease phase of a single battery cell during multiple target constant-voltage discharging processes after reaching the discharging cutoff voltage multiple times.

[0268] As an example, the process of achieving constant voltage charging can be a continuous charging process. As another example, the process of achieving constant voltage discharging can be a continuous discharging process.

[0269] As an example, charging a single battery cell to the charging cutoff voltage and then the target constant voltage charging after reaching the charging cutoff voltage can be achieved using a constant voltage charging method or a constant current constant voltage charging method.

[0270] For example, when a battery cell is charged using a constant-voltage charging method, the voltage remains constant while the current gradually decreases. The target constant-voltage charging process after reaching the charging cutoff voltage can be considered as the charging process where the battery cell voltage reaches the charging cutoff voltage during constant-voltage charging. The target stage can also be the stage after the battery cell voltage reaches the charging cutoff voltage during constant-voltage charging.

[0271] For example, when a battery cell is charged using a constant current / constant voltage charging method, in the constant current charging phase, the battery cell is charged with a constant current. When the voltage of the battery cell reaches the charging cutoff voltage, it enters the constant voltage charging phase, where the battery cell is charged with a constant voltage and the current gradually decreases. The process of reaching the target constant voltage charging cutoff voltage can be considered the constant voltage charging phase in a constant current / constant voltage charging method. The target phase can also be considered the constant voltage charging phase in a constant current / constant voltage charging method.

[0272] However, generally speaking, during constant-voltage charging of a battery cell (which can be constant-voltage charging or constant-current / constant-voltage charging), due to the presence of polarization such as ohmic polarization, electrochemical polarization, and concentration polarization, as shown in Figure 10, constant-voltage charging can include two sub-stages: In the first sub-stage of constant-voltage charging, due to the presence of electrochemical polarization and concentration polarization within the battery cell, the constant-voltage charging current remains at its upper limit of allowable current; subsequently, in the second sub-stage of constant-voltage charging, the current gradually decreases. In this case, the stage where the current gradually decreases (the second sub-stage) can be considered the target stage.

[0273] As an example, by taking the moment when the current drops in Figure 10 as time 0, we can obtain information on the change of current over time in the target stage of the battery cell as shown in Figure 11.

[0274] Of course, the trend of current change during the stage of discharge current decrease in the process of constant voltage discharge from a single battery cell to the discharge cutoff voltage is similar to that during the stage of charging current decrease in the process of constant voltage charging.

[0275] As an example, the discharge of a single battery cell to the discharge cutoff voltage and the target constant voltage discharge after discharge to the discharge cutoff voltage can be achieved by constant voltage discharge or by transverse current constant voltage discharge.

[0276] As an example, when a battery cell discharges using a constant-voltage discharge method, the discharge voltage is constant while the current gradually decreases. The constant-voltage discharge process that reaches the target discharge cutoff voltage can be considered as the discharge process after the voltage of the battery cell reaches the discharge cutoff voltage during the constant-voltage discharge process. The target stage can also be considered as the discharge process after the voltage of the battery cell reaches the discharge cutoff voltage during the constant-voltage discharge process.

[0277] As an example, when a battery cell is discharged using a constant current and constant voltage discharge method, in the constant current discharge stage, the battery cell discharges with a constant current. When the voltage of the battery cell reaches the discharge cutoff voltage, it enters the constant voltage discharge stage, where the battery cell discharges with a constant voltage and the current gradually decreases. The process of reaching the target constant voltage discharge cutoff voltage can be considered the discharge process of the constant voltage discharge stage in a constant current and constant voltage discharge method. The target stage can also be considered the constant voltage discharge stage in a constant current and constant voltage discharge method.

[0278] It should be understood that the current and time information of a single battery cell in the target stage can be in the form shown in Figure 9, or in numerical form, or in other forms. This application does not limit the form in which the current and time information is presented.

[0279] As an example, one can obtain 3000 SOH values ​​corresponding to 3000 charge-discharge cycles for a single battery cell, as well as information on the current and time of the target stage corresponding to 3000 charge-discharge cycles.

[0280] 930. Based on the current and time information of individual cells in multiple target stages, determine multiple slope values ​​of the current-time functional relationship in multiple target stages.

[0281] Using the current and time information of a target stage, a current-time functional relationship can be obtained, and then the slope value of this functional relationship can be determined. Therefore, based on the current and time information of multiple target stages, multiple current-time functional relationships of multiple target stages can be obtained, and then multiple slope values ​​corresponding to these multiple functional relationships can be determined.

[0282] The current-time function relationship in the target stage can be expressed as a function of m(I)-n(t), where m(I) is a function related to the current I in the target stage, and n(t) is a parameter related to the time t in the target stage. That is, the horizontal axis of this function relationship can be either m(I) or n(t), and the vertical axis can be either m(I) or n(t).

[0283] As an example, the current-time function relationship for a target stage can be: The functional relationship, whose ordinate can be... (i.e., n(t)), the abscissa of this functional relationship can be 1 / I (i.e., m(I)).

[0284] For example, the ordinate of a target line can be The horizontal axis is 1 / I. Where t is the time of the current decrease phase during the constant voltage charging process of the target, and I is the current during the current decrease phase during the constant voltage charging process of the target; or, t is the time of the current decrease phase during the constant voltage discharging process of the target, and I is the current during the current decrease phase during the constant voltage discharging process of the target.

[0285] As an example, the current-time function relationship of a target stage can be obtained as a curve, and the slope value of the fitted curve can be used as the slope value of the current-time function relationship of the target stage.

[0286] As another example, the current-time function of a target stage can be represented by a straight line. The slope of this line can be used as the slope of the current-time function of the target stage.

[0287] Generally speaking, based on the information of current and time during the current-time decrease phase in a target constant voltage charging process, or based on the information of current and time during the current-time decrease phase in a target constant voltage discharging process, a slope value corresponding to a current-time function relationship can be obtained.

[0288] 940. Based on multiple slope values ​​and multiple SOH values ​​corresponding to multiple charge-discharge cycles, an SOH prediction model is established.

[0289] Multiple charge-discharge cycles correspond to multiple slope values ​​and multiple SOH values.

[0290] SOH prediction models can come in various forms, as shown in the following examples:

[0291] As an example, multiple slope values ​​and their corresponding SOH values ​​can be input into a training model, such as a neural network model, to obtain an SOH prediction model. This SOH prediction model can output the SOH value of a battery cell based on the current and time information of the battery cell at the target stage.

[0292] As an example, multiple slope values ​​and their corresponding SOH values ​​can be processed to obtain a formulaic SOH prediction model, such as K = a(1-SOH) + b. Here, K is the slope value, and SOH is the SOH value of the battery cell. The model can be based on the battery cell with the target stage current as the ordinate and... (t is the time of the target stage) is the slope value of the target line determined by the horizontal axis, and the SOH value of the battery cell is calculated by this formula.

[0293] As an example, multiple slope values ​​and corresponding multiple SOH values ​​can also be processed to obtain other forms of SOH prediction models, such as the corresponding graph form of the SOH prediction model shown in Figure 7. The vertical axis of the corresponding graph is the slope, and the horizontal axis of the corresponding graph is 1-SOH.

[0294] As an example, the number of battery cells used to establish the SOH prediction model can be one or more. The SOH prediction model can be obtained based on multiple slope values ​​and multiple SOH values ​​corresponding to multiple charge-discharge cycles of multiple battery cells. For example, each charge-discharge cycle of multiple battery cells can correspond to multiple slope values ​​and multiple SOH values. The average of the multiple slope values ​​and multiple SOH values ​​can be used as the first average value and the second average value, respectively. Then, multiple charge-discharge cycles of multiple batteries can correspond to multiple first average values ​​and multiple second average values. Based on the multiple first average values ​​and multiple second average values, the SOH prediction model can be established.

[0295] In this embodiment of the application, the method for obtaining the SOH prediction model provided in this embodiment can establish an SOH prediction model based on multiple SOH values ​​corresponding to multiple charge-discharge cycles of a battery cell and the slope value of the target line determined by the current and time information of multiple target stages. Thus, the SOH of the battery cell can be accurately detected by using the slope value of the target line determined during the use of the battery cell and the SOH prediction model.

[0296] In some embodiments, the total coordinates of a target line can be I, and the x-coordinate can be...

[0297] That is, the current at multiple target stages can be used as the vertical axis, and the current corresponding to multiple target stages can be used as the horizontal axis. As the horizontal axis, multiple target lines are obtained, and multiple slope values ​​of the multiple target lines are determined.

[0298] t represents the time corresponding to each of the multiple target stages.

[0299] As an example, in this application, the current of a target stage is used as the vertical axis, and the current of a target stage is used as the horizontal axis. Using the horizontal axis as the abscissa, a target line can be obtained, and then the slope value of this target line can be determined. Therefore, based on the current and time information of multiple target stages, multiple target lines can be obtained, and then multiple slope values ​​of these multiple target lines can be determined.

[0300] As an example, the vertical axis of a target line can represent the current during the current-decreasing phase of a target constant-voltage charging process, and the horizontal axis can represent... t represents the time of the current decrease phase during a single constant-voltage charging process of the target. Alternatively, the vertical axis of a target line can represent the current during the current decrease phase during a single constant-voltage discharging process of the target, and the horizontal axis can represent... t represents the time of the current decrease phase during the constant voltage discharge of the target.

[0301] As an example, the target line can be a curve. The slope value of the fitted curve can be used as the slope value of the target line. For example, by processing the curve of the charging current changing with time in the target stage shown in Figure 11, the charging current in the target stage shown in Figure 12 is obtained. The functional relationship is shown in Figure 12. The vertical axis of the target line represents the charging current during the constant voltage charging process, and the horizontal axis represents the... t represents the time it takes for the charging current to decrease during the target constant voltage charging process. The slope of the fitted curve shown in Figure 12 can be used as the slope value of the target line.

[0302] As another example, the target line can also be a straight line. The slope value of this straight line can be used as the slope value of the target line. For example, the straight line could be one with the current of the target stage as the vertical axis and the horizontal axis as the vertical axis. The fitted straight line is obtained by using it as the x-axis.

[0303] In some embodiments, the multiple target stages include the stage after the current decreases for 100 seconds during multiple target constant voltage charging processes or the stage after the current decreases for 100 seconds during multiple target constant voltage discharging processes, and t=0 corresponds to the moment when the current begins to decrease during the target constant voltage charging process or the target constant voltage discharging process.

[0304] The stage after the current drops by 100s, i.e., t≥100s, corresponds to For example, the interval after the 100th second of the charging current decrease in Figure 11 corresponds to the interval in Figure 12. The range.

[0305] As can be seen from Figure 12, Within the interval, the current follows The trend of change is close to a straight line, that is, the target line is close to a straight line, and the slope value of the target line can be determined more accurately.

[0306] In the embodiments of this application, the target line determined by the current and time after the current drops for 100 seconds during the target constant voltage discharge process, or the current and time after the current drops for 100 seconds during the target constant voltage discharge process, is close to a straight line. The SOH prediction model obtained by the slope value of the target line that is close to a straight line can accurately determine the SOH of the battery cell.

[0307] In some embodiments, the multiple target stages include the stage after the current decreases for 150 seconds during multiple target constant voltage charging processes or the stage after the current decreases for 150 seconds during multiple target constant voltage discharging processes, and t=0 corresponds to the moment when the current begins to decrease during the target constant voltage charging process or the target constant voltage discharging process.

[0308] The stage after the current drops by 150s, i.e., t≥150s, corresponds to Approximately ≤0.082. As can be seen from Figure 12, in... Within the range of approximately 0.08, the target line is closer to a straight line, thus allowing for a more accurate determination of the slope value of the target line.

[0309] In the embodiments of this application, the target line determined by the current and time after the current drops for 150 seconds during the target constant voltage discharge process, or the current and time after the current drops for 150 seconds during the target constant voltage discharge process, is closer to a straight line. The SOH prediction model obtained by using the slope value of the target line that is close to a straight line can accurately determine the SOH of the battery cell.

[0310] On the other hand, it can greatly reduce the amount of data required to obtain the SOH prediction model for individual battery cells, thereby reducing data overhead.

[0311] In some embodiments, the multiple target stages respectively include a stage between the 150s and 1000s of current decrease during multiple target constant voltage charging processes or a stage between the 150s and 1000s of current decrease during multiple target constant voltage discharging processes.

[0312] In this embodiment, by selecting the target stage between 150s and 1000s during the current drop in the target constant voltage charging process or the target constant voltage discharging process, the determined target line is made closer to a straight line. The SOH prediction model obtained using the slope value of this near-straight target line can accurately determine the SOH of a single battery cell. Furthermore, this significantly reduces the amount of data required for the target stage, thereby reducing data overhead.

[0313] Figure 13 is a flowchart illustrating the method for obtaining the SOH prediction model provided in an embodiment of this application.

[0314] 1310 involves performing multiple charge-discharge cycles on individual battery cells.

[0315] For details regarding multiple charge-discharge cycles, please refer to the relevant content in step 910; this application will not elaborate further here.

[0316] In the embodiments of this application, by performing multiple charge-discharge cycles on a single battery cell, it is easy to obtain multiple SOH values ​​of the battery cell in multiple charge-discharge cycles, as well as information on the current and time of the battery cell in multiple target stages, thereby facilitating the establishment of an SOH prediction model for the battery cell.

[0317] In some embodiments, a single battery cell can be subjected to multiple charge-discharge cycles to bring the battery cell to the end-of-life (EOL) state.

[0318] As an example, the end-of-life (EOL) state of a battery cell can be defined as the number of charge-discharge cycles a certain number, such as more than 3,000, or the state of harmonics (SOH) of the battery cell reduced to a certain value, such as below 80%.

[0319] In this embodiment of the application, by performing multiple charge-discharge cycles on a single battery cell to reach the end-of-life (EOL) state, the first and second information of the battery cell throughout its entire lifespan can be obtained to establish a state-of-the-art (SOH) prediction model for the battery cell from charge-discharge cycle to EOL state, thereby enabling the detection of SOH of the battery cell in the EOL state.

[0320] 1320, obtain the SOH evaluation parameters of the battery cell after multiple charge-discharge cycles.

[0321] As an example, SOH evaluation parameters may include capacity, internal resistance, etc.

[0322] 1330. Based on the SOH evaluation parameters corresponding to multiple charge-discharge cycles of a single battery cell, determine the first information.

[0323] The first piece of information includes multiple SOH values ​​corresponding to multiple charge-discharge cycles of a single battery cell.

[0324] SOH evaluation parameters include parameters that can be used to determine SOH, such as the capacity, internal resistance, and cycle life of individual cells.

[0325] As an example, first information can be obtained based on the ratio of the charging capacity of a battery cell during multiple 100% full charges in multiple charge-discharge cycles to the capacity of the battery cell during its first 100% full charge, and / or based on the ratio of the discharge capacity of a battery cell during multiple 100% full discharges in multiple charge-discharge cycles to the capacity of the battery cell during its first 100% full discharge.

[0326] When determining the SOH value of a battery cell by its capacity, multiple charge-discharge cycles of the battery cell can be charge-discharge cycles consisting of 100% full charge and 100% full discharge.

[0327] In the embodiments of this application, the SOH value of a battery cell after multiple charge-discharge cycles can be accurately determined by the SOH evaluation parameter of the battery cell, thereby obtaining an accurate SOH prediction model for the battery cell.

[0328] When the State of Harm (SOH) value of a battery cell in multiple charge-discharge cycles is determined by other SOH evaluation parameters, the multiple charge-discharge cycles of a battery cell can be charge-discharge cycles of 100% complete charge and 100% complete discharge, or they can be charge from a non-zero capacity (e.g., 30%) to 100% capacity and then discharge to a non-zero capacity, or they can be charge from zero capacity to a non-100% capacity (e.g., 70%) and then discharge to zero capacity. In this application, the capacity of the battery charge-discharge cycle can be determined based on the SOH evaluation parameters.

[0329] For details regarding the first information, please refer to the description in step 910. For the sake of brevity, this application will not repeat the details here.

[0330] 1340, obtain the second information.

[0331] The second information includes information on the current and time of a single battery cell in multiple target stages, which include stages where the current decreases during multiple target constant voltage charging processes or stages where the current decreases during multiple target constant voltage discharging processes.

[0332] 1350, with the current at multiple target stages as the vertical axis and the current corresponding to multiple target stages as the horizontal axis. As the horizontal axis, multiple target lines are obtained, and multiple slope values ​​of the multiple target lines are determined.

[0333] t represents the time corresponding to each of the multiple target stages.

[0334] 1360. Based on multiple slope values ​​and multiple SOH values ​​corresponding to multiple charge-discharge cycles, an SOH prediction model is established.

[0335] The contents of steps 1340 to 1360 can be found in steps 920 to 940 and the relevant descriptions above, and will not be repeated here.

[0336] Figure 14 is a flowchart illustrating the method for establishing a SOH prediction model provided in an embodiment of this application.

[0337] 1410a performs multiple charge-discharge cycles on a single battery cell, from charging to charging to charging to constant voltage charging to discharging to the discharge cutoff voltage.

[0338] The constant voltage charging in step 1410a includes the target constant voltage charging.

[0339] In some embodiments, different discharge methods can be used to discharge individual cells to the discharge cutoff voltage.

[0340] In this embodiment, the discharge of a single battery cell to the discharge cutoff voltage can be either constant current / constant voltage discharge or constant voltage discharge. This application does not limit the method of discharge to the discharge cutoff voltage.

[0341] In the embodiments of this application, by performing multiple charge-discharge cycles on a single battery cell from charging to charging to charging to constant voltage charging to discharging to discharging to the charging to charging to constant voltage charging, it is convenient to obtain information on the current and time during the current drop phase of multiple target constant voltage charging processes of the single battery cell during multiple charge-discharge cycles, that is, it is convenient to obtain information on the current and time of multiple target phases.

[0342] In some embodiments, the battery cells can be charged in different ways to charge the battery cells from the discharge cutoff voltage to the charge cutoff voltage.

[0343] As an example, a single battery cell can be charged with a constant current to charge it to the charging cutoff voltage.

[0344] Constant current charging can take different forms. For example, it can be performed by charging individual battery cells at a constant charging rate or by performing constant current charging in a gradient manner.

[0345] Gradient constant current charging can also be called segmented constant current charging. That is, constant current charging is divided into multiple stages, and each stage is charged with a constant current. The currents in the multiple stages are different, such as the currents in the multiple stages showing a gradually decreasing trend.

[0346] In the embodiments of this application, constant current charging of individual battery cells to the charging cutoff voltage can improve charging efficiency, reduce the charging time, and thus reduce the time cost of establishing a SOH prediction model.

[0347] Optionally, the individual battery cells can be charged at a constant voltage to the charging cutoff voltage, and then the battery can continue to be charged at a constant voltage (target constant voltage charging).

[0348] That is, the battery cells are charged at a constant voltage both before and after they are charged to the charging cutoff voltage.

[0349] In some embodiments, the battery cells are charged at a constant voltage to the charging cutoff current.

[0350] In the embodiments of this application, by charging the individual battery cells to the charging cutoff current, the battery can be fully charged, while also facilitating the control of the termination of charging of the individual battery cells.

[0351] 1410b performs multiple charge-discharge cycles on a single battery cell, from charging to charging to charging to discharging to discharging to discharging to constant voltage discharge.

[0352] Constant voltage discharge includes target constant voltage discharge.

[0353] In some embodiments, different charging methods can be used for individual battery cells to charge them from the discharge cutoff voltage to the charging cutoff voltage. For example, a constant current / constant voltage charging method or a constant voltage discharging method can be used. This application does not limit the method of discharging to the discharge cutoff voltage.

[0354] In the embodiments of this application, by performing multiple charge-discharge cycles from the discharge cutoff voltage to the charge cutoff voltage, then to the discharge cutoff voltage, and finally to constant voltage discharge, it is convenient to obtain information on the current and time during the current decrease phase of multiple target constant voltage discharge processes of a single battery cell, that is, to obtain information on the current and time of multiple target phases.

[0355] In some embodiments, different discharge methods can be used to discharge individual battery cells to the discharge cutoff voltage. As an example, a constant current discharge can be applied to the individual battery cells to discharge them to the discharge cutoff voltage.

[0356] Constant current discharge can take different forms. For example, it can be performed by constant current discharge of a single battery cell at a constant discharge rate, or it can be performed by constant current discharge of a single battery cell in a gradient constant current discharge manner.

[0357] Gradient constant current discharge can also be called segmented constant current discharge. That is, constant current discharge is divided into multiple stages, and each stage discharges with a constant current. The currents in the multiple stages are different, such as the current in the multiple stages showing a gradually decreasing trend.

[0358] In the embodiments of this application, by performing constant current discharge on individual battery cells, the discharge efficiency can be improved and the discharge time can be reduced, thereby reducing the time cost of establishing a SOH prediction model.

[0359] Alternatively, the individual battery cells can be discharged at a constant voltage until the discharge cutoff voltage is reached.

[0360] In some embodiments, in step 14140b, the battery cell is subjected to constant voltage discharge to discharge to the discharge cutoff current.

[0361] In the embodiments of this application, by discharging the battery cell to the discharge cutoff current, it is convenient to control the termination of the discharge of the battery cell.

[0362] 1420, obtain the SOH evaluation parameters of the battery cell after multiple charge-discharge cycles.

[0363] 1430. Based on the SOH evaluation parameters, determine the first information.

[0364] The first piece of information includes multiple SOH values ​​corresponding to multiple charge-discharge cycles of a single battery cell.

[0365] Multiple charge-discharge cycles satisfy at least one of the following conditions: multiple charging in multiple charge-discharge cycles includes multiple charging to the charging cutoff voltage and multiple charging to the charging cutoff voltage followed by multiple target constant voltage charging; multiple discharging in multiple charge-discharge cycles includes multiple discharging to the discharging cutoff voltage and multiple discharging to the discharging cutoff voltage followed by multiple target constant voltage discharging.

[0366] 1440, obtain the second information.

[0367] The second information includes the current and time information of the battery cells in multiple target stages, which include the current decrease stage during multiple target constant voltage charging processes or the current decrease stage during multiple target constant voltage discharging processes.

[0368] 1450, with the current at multiple target stages as the vertical axis and the current corresponding to multiple target stages as the horizontal axis. As the horizontal axis, multiple target lines are obtained, and multiple slope values ​​of the multiple target lines are determined.

[0369] t represents the time corresponding to each of the multiple target stages.

[0370] 1460. Based on multiple slope values ​​and multiple SOH values ​​corresponding to multiple charge-discharge cycles, an SOH prediction model is established.

[0371] The contents of steps 1420 to 1460 can be found in the descriptions of steps 910 to 940 and steps 1320 and 1330, and will not be repeated here.

[0372] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0373] The foregoing has described in detail the method for detecting battery cells and the method for obtaining SOH prediction models according to embodiments of this application. The following will describe in detail the device for detecting battery cells according to embodiments of this application with reference to Figures 15 and 16, and the device for obtaining SOH prediction models according to embodiments of this application with reference to Figures 17 and 18. The technical features described in the method embodiments are applicable to the following device embodiments.

[0374] Figure 15 is a schematic block diagram of a battery cell detection device provided in an embodiment of this application. As shown in Figure 15, the detection device 4000 includes some or all of the following components.

[0375] The detection device 4000 includes an acquisition unit 4100 and a processing unit 4200.

[0376] The acquisition unit 4100 is used to acquire information on the current and time of a single battery cell in a target stage, which includes a stage in which the current decreases during the target constant voltage charging process after reaching the charging cutoff voltage or a stage in which the current decreases during the target constant voltage discharging process after reaching the discharging cutoff voltage; the processing unit 4200 is used to determine the slope value of the current-time function relationship in the target stage based on the current and time information in the target stage; and to detect the single battery cell based on the slope value.

[0377] In some embodiments, the processing unit 4200 is configured to use the current at the target stage as the vertical axis and... The target line is obtained as the horizontal axis, and the slope value of the target line is determined, where t is the time of the target stage.

[0378] In some embodiments, the processing unit 4200 is configured to determine whether a battery cell has broken based on changes in the slope value.

[0379] In some embodiments, the acquisition unit 4100 is used to acquire current and time information of a single battery cell in multiple target stages, the multiple target stages including the current decrease stage during multiple target constant voltage charging processes or multiple target constant voltage discharging processes.

[0380] In some embodiments, the processing unit 4200 is configured to use the current of multiple target stages as the vertical axis and the current corresponding to the multiple target stages as the horizontal axis. As the horizontal axis, multiple target lines are obtained, and multiple slope values ​​of the multiple target lines are determined.

[0381] In some embodiments, the processing unit 4200 is configured to determine that a battery cell has broken when the trend of change of multiple slope values ​​is downward and the degree of decline is greater than or equal to a preset degree.

[0382] In some embodiments, the plurality of target stages include a first, an nth, and an (n+1)th target stage, and the first, nth, and (n+1)th target stages include the current decrease phases during the first, nth, and (n+1)th target constant voltage charging processes, respectively. The processing unit 4200 is configured to... In the case where it is determined that the battery cell breaks in the (n+1)th target stage, K n K represents the slope value of a single battery cell in the nth target stage. n+1K is the slope value of the battery cell in the (n+1)th target stage, K1 is the slope value of the battery cell in the 1st target stage, and K 预设 This is the default value.

[0383] In some embodiments, K 预设 ≥20%.

[0384] In some embodiments, the processing unit 4200 is configured to determine the SOH value of a single battery cell based on the slope value.

[0385] In some embodiments, the processing unit 4200 is configured to determine the SOH value of a single battery cell based on the slope value and the SOH prediction model, wherein the SOH prediction model includes a correspondence between multiple slope values ​​and multiple SOH values.

[0386] In some embodiments, the target stage includes the stage after the current decreases during the target constant voltage charging process, 100 seconds later, and t=0 corresponds to the moment when the current begins to decrease during the target constant voltage charging process.

[0387] In some embodiments, the target phase includes the phase between the 150s and 1000s during the current drop in the target constant voltage charging process.

[0388] It should be understood that the above and other operations and / or functions of the various modules in the battery cell detection device 4000 are for the purpose of implementing the corresponding processes in the various methods of Figures 1 to 8, and for the sake of brevity, they will not be described in detail here.

[0389] Figure 16 shows a schematic block diagram of a battery cell detection device 5000 according to an embodiment of this application. As shown in Figure 16, the detection device 5000 includes a processor 5010 and a memory 5020, wherein the memory 5020 is used to store instructions, and the processor 5010 is used to read instructions and execute the methods of the various embodiments of this application described above based on the instructions.

[0390] The memory 5020 can be a separate device independent of the processor 5010, or it can be integrated into the processor 5010.

[0391] Optionally, as shown in Figure 16, the battery cell detection device 5000 may further include a transceiver 5030, and the processor 5010 may control the transceiver 5030 to communicate with other devices. Specifically, it may send information or data to other devices, or receive information or data sent by other devices.

[0392] Figure 17 is a schematic block diagram of an apparatus for obtaining a SOH prediction model provided in an embodiment of this application. As shown in Figure 17, the apparatus 6000 includes some or all of the following components.

[0393] The device 6000 includes a processing unit 6100 and an acquisition unit 6200.

[0394] Processing unit 6100 is used to determine first information, which includes multiple SOH values ​​corresponding to multiple charge-discharge cycles of a battery cell. The multiple charge-discharge cycles satisfy at least one of the following conditions: multiple charging in the multiple charge-discharge cycles includes multiple charging to the charging cutoff voltage and multiple target constant-voltage charging after multiple charging to the charging cutoff voltage; multiple discharging in the multiple charge-discharge cycles includes multiple discharging to the discharging cutoff voltage and multiple discharging to the discharging cutoff voltage and multiple target constant-voltage discharging after multiple discharging. Acquisition unit 6200 is used to acquire second information, which includes current and time information of the battery cell in multiple target stages. The multiple target stages include stages where the current decreases during multiple target constant-voltage charging or stages where the current decreases during multiple target constant-voltage discharging. Processing unit 6100 determines multiple slope values ​​of the current-time function relationship of the multiple target stages based on the current and time information of the multiple target stages; and establishes an SOH prediction model based on the multiple SOH values ​​and multiple slope values ​​corresponding to the multiple charge-discharge cycles.

[0395] In some embodiments, the multiple target stages each include the stage after the current decreases in the process of multiple target constant voltage charging, and t=0 corresponds to the moment when the current begins to decrease in the process of target constant voltage charging.

[0396] In some embodiments, the multiple target stages each include a stage between the 150th and 1000th seconds of current decrease during multiple target constant voltage charging processes.

[0397] In some embodiments, the processing unit 6100 is used to perform multiple charge-discharge cycles on a single battery cell.

[0398] In some embodiments, the processing unit 6100 is used to perform multiple charge-discharge cycles on a single battery cell to bring the battery cell to the end-of-life (EOL) state.

[0399] In some embodiments, the acquisition unit 6200 is used to acquire the SOH evaluation parameters of a single battery cell during multiple charge-discharge cycles; the processing unit 6100 is used to determine first information based on the SOH evaluation parameters.

[0400] It should be understood that the above and other operations and / or functions of the various modules in the apparatus 6000 for acquiring the SOH prediction model are to implement the corresponding processes in the various methods of Figures 9 to 14, and for the sake of brevity, will not be described in detail here.

[0401] Figure 18 shows a schematic block diagram of an apparatus 7000 for obtaining a SOH prediction model according to an embodiment of this application. As shown in Figure 18, the apparatus 7000 includes a processor 7010 and a memory 7020, wherein the memory 7020 is used to store instructions, and the processor 7010 is used to read instructions and execute the methods of the various embodiments of this application described above based on the instructions.

[0402] The memory 7020 can be a separate device independent of the processor 7010, or it can be integrated into the processor 7010.

[0403] Optionally, as shown in Figure 18, the apparatus 7000 for acquiring the SOH prediction model may further include a transceiver 7030, and the processor 7010 may control the transceiver 7030 to communicate with other devices. Specifically, it may send information or data to other devices, or receive information or data sent by other devices.

[0404] It should be understood that the processor in the embodiments of this application may be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above method embodiments can be completed by integrated logic circuits in the processor's hardware or by instructions in software form. The processor described above can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0405] It is understood that the memory in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory used in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0406] Optionally, embodiments of this application also provide an electrical device, which includes a battery, a thermal management system for the battery, and a detection device provided in embodiments of this application.

[0407] This application also provides a computer-readable storage medium for storing computer programs.

[0408] Optionally, the computer-readable storage medium can be applied to the detection device of the battery system in the embodiments of this application, and when the computer program is run on the computer, it causes the computer to execute the corresponding processes implemented by the detection device in the various methods of the embodiments of this application. For the sake of brevity, it will not be described in detail here.

[0409] This application also provides a computer program product, including computer program instructions.

[0410] Optionally, the computer program product can be applied to the battery system detection device in the embodiments of this application, and the computer program instructions, when run on a computer, cause the computer to execute the corresponding processes implemented by the battery system detection device in the various methods of the embodiments of this application. For the sake of brevity, they will not be described in detail here.

[0411] This application also provides a computer program.

[0412] Optionally, the computer program can be applied to the battery system detection device in the embodiments of this application. When the computer program is run on a computer, it causes the computer to execute the corresponding processes implemented by the battery system detection device in the various methods of the embodiments of this application. For the sake of brevity, it will not be described in detail here.

[0413] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0414] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0415] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection involved in the embodiments of this application may be through some interfaces, and the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms.

[0416] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0417] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0418] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0419] 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 a single battery cell, characterized in that, The detection method includes: Information on the current and time of a single battery cell in a target stage is obtained. The target stage includes the stage of current decrease during the target constant voltage charging process after reaching the charging cutoff voltage or the stage of current decrease during the target constant voltage discharging process after reaching the discharging cutoff voltage. Based on the current and time information of the battery cell in the target stage, determine the slope value of the current-time function relationship in the target stage; The individual battery cells are tested based on the slope value.

2. The detection method according to claim 1, characterized in that, The step of determining the slope value of the current-time function relationship in the target stage based on the current and time information of the battery cell in the target stage includes: Using the current at the target stage as the ordinate, and... The target line is obtained as the horizontal axis, and the slope value of the target line is determined, where t is the time of the target stage.

3. The detection method according to claim 1 or 2, characterized in that, The step of detecting the battery cell based on the slope value includes: Based on the change in the slope value, it is determined whether the battery cell has broken.

4. The detection method according to claim 3, characterized in that, The acquisition of information on the current and time of a single battery cell at the target stage includes: Acquire current and time information of individual battery cells during multiple target stages, each of which includes multiple target constant voltage charging processes.

5. The detection method according to claim 2, characterized in that, The current at the target stage is used as the vertical axis, and... The target line is obtained as the horizontal axis, and the slope value of the target line is determined, including: Using the current of each of the plurality of target stages as the ordinate and the current corresponding to each of the plurality of target stages as the coordinates, respectively... Using the horizontal axis as the abscissa, multiple target lines are obtained, and multiple slope values ​​of the multiple target lines are determined.

6. The detection method according to claim 5, characterized in that, The step of determining whether the battery cell is broken based on the change in the slope value includes: If the trend of the multiple slope values ​​is downward and the degree of decline is greater than or equal to a preset degree, it is determined that the battery cell has broken.

7. The detection method according to claim 5 or 6, characterized in that, The plurality of target stages include the 1st, nth, and n+1th target stages, wherein the 1st, nth, and n+1th target stages include the current decrease phases during the 1st, nth, and n+1th target constant voltage charging processes, and determining the cell rupture based on the change in slope value includes: exist In the case where it is determined that the battery cell breaks in the (n+1)th target stage, K n K represents the slope value corresponding to the nth target stage of the battery cell. n+1 K1 is the slope value corresponding to the battery cell in the (n+1)th target stage, K1 is the slope value corresponding to the battery cell in the 1st target stage, K 预设 This is the default value.

8. The detection method according to claim 7, characterized in that, K 预设 ≥20％。 9. The detection method according to any one of claims 1 to 8, characterized in that, The step of detecting the battery cell based on the slope value includes: The SOH value of the battery cell is determined based on the slope value.

10. The detection method according to claim 9, characterized in that, Determining the SOH value of the battery cell based on the slope value includes: The SOH value of the battery cell is determined based on the slope value and the SOH prediction model, wherein the SOH prediction model includes the correspondence between multiple slope values ​​and multiple SOH values.

11. The detection method according to any one of claims 1 to 10, characterized in that, The target stage includes the stage after the current decreases during the target constant voltage charging process, and the moment when the current begins to decrease during the target constant voltage discharging process at t=0.

12. The detection method according to claim 10, characterized in that, The target phase includes the period between 150s and 1000s during the current drop in the target constant voltage charging process.

13. A method for obtaining a SOH prediction model, characterized in that, The method includes: First information is determined, which includes multiple SOH values ​​corresponding to multiple charge-discharge cycles of a single battery cell. The multiple charge-discharge cycles satisfy at least one of the following conditions: multiple charging in the multiple charge-discharge cycles includes multiple charging to the charging cutoff voltage and multiple charging to the charging cutoff voltage followed by multiple target constant voltage charging; multiple discharging in the multiple charge-discharge cycles includes multiple discharging to the discharging cutoff voltage and multiple discharging to the discharging cutoff voltage followed by multiple target constant voltage discharging. Obtain second information, which includes information on the current and time of the battery cell in multiple target stages, including the current decrease stage during multiple target constant voltage charging or the current decrease stage during multiple target constant voltage discharging. Based on the current and time information of the battery cell in the multiple target stages, determine multiple slope values ​​of the current-time functional relationship in the multiple target stages; An SOH prediction model is established based on the multiple SOH values ​​and multiple slope values ​​corresponding to the multiple charge-discharge cycles.

14. The method according to claim 13, characterized in that, The step of determining multiple slope values ​​of the current-time functional relationship for the multiple target stages based on the current and time information of the battery cell in the multiple target stages includes: Using the current of the plurality of target stages as the ordinate and the current corresponding to the plurality of target stages as the coordinates, respectively... Using the x-axis as the horizontal axis, multiple target lines are obtained, and multiple slope values ​​of the multiple target lines are determined, where t is the time corresponding to each of the multiple target stages.

15. The method according to claim 13 or 14, characterized in that, Before determining the first information and obtaining the second information, the method further includes: The battery cell is subjected to the aforementioned multiple charge-discharge cycles.

16. The method according to claim 15, characterized in that, The process of performing multiple charge-discharge cycles on the battery cell includes: The battery cell is subjected to multiple charge-discharge cycles to bring it to the end-of-life (EOL) state.

17. The method according to any one of claims 13 to 16, characterized in that, Before determining the first information, the method further includes: Obtain the SOH evaluation parameters of the battery cell corresponding to the multiple charge-discharge cycles; The determination of the first information includes: The first information is determined based on the SOH evaluation parameters.

18. A device for detecting a single battery cell, characterized in that, The detection device includes: The acquisition unit is used to acquire information on the current and time of a single battery cell in a target stage. The target stage includes a stage in which the current decreases during the target constant voltage charging process after reaching the charging cutoff voltage or a stage in which the current decreases during the target constant voltage discharging process after reaching the discharging cutoff voltage. The processing unit is used to determine the slope value of the current-time function relationship of the target stage based on the current and time information of the battery cell in the target stage. The processing unit is used to detect the battery cell based on the slope value.

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