A method and device for detecting the CB value of a lithium ion battery cell, and a storage medium

Abstract

The application discloses a lithium ion cell CB value detection method and device and a storage medium, and relates to the technical field of cell quality control detection, wherein the detection method comprises the following steps: acquiring CB values of a plurality of sample cells; performing constant-voltage charging on the sample cells at a first voltage respectively, and recording a first charging time corresponding to each sample cell; establishing a mapping relationship equation according to the CB values of the sample cells and the corresponding first charging times; performing constant-voltage charging on a detection cell at the first voltage to obtain a second charging time of the detection cell; and calculating the CB value of the detection cell according to the second charging time and the mapping relationship equation. The application can conveniently and quickly calculate the CB value of the cell.

Description

Technical Field

[0001] This application relates to the field of battery cell quality control and testing technology, and in particular to a method, apparatus and storage medium for detecting the CB value of lithium-ion battery cells. Background Technology

[0002] Currently, the application voltage of lithium cobalt oxide batteries is basically in the high voltage stage of 4.48V / 4.50V. At this time, the lithium cobalt oxide material is at the critical point of the H1-3 phase transition. Due to individual differences in the cells, some cells may have a higher CB (Cell Balance, the excess ratio of negative electrode capacity to positive electrode capacity per unit area on the front side) value due to fluctuations in coating density. This will lead to more lithium delithiation of lithium cobalt oxide, exceeding the H1-3 phase transition point, resulting in a sharp deterioration in the performance of the cell, especially the high temperature cycling performance.

[0003] The CB value of a battery cell cannot be effectively calculated from the initial data such as the cell's capacity, internal resistance, K-value, and mass. The most efficient way to obtain the CB value of each cell is to weigh the positive and negative electrodes separately during the cell winding process, and then calculate the CB value of the individual cell. However, this method is not feasible for continuous mass production. It not only wastes a lot of manpower and resources, but manual weighing can also cause various kinds of damage to the electrodes, ultimately deteriorating the cell's performance. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a method, apparatus, and storage medium for detecting the CB value of a lithium-ion battery cell, which can conveniently and quickly calculate the CB value of the cell.

[0005] Firstly, this application provides a method for detecting the CB value of a lithium-ion battery cell, including: Obtain the CB values ​​of several sample cells; The sample cells are charged at a constant voltage with a first voltage, and the first charging time corresponding to each sample cell is recorded. A mapping equation is established based on the CB value of the sample battery cell and the corresponding first charging time; The test cell is charged at a constant voltage using the first voltage to obtain the second charging time of the test cell; The CB value of the detected battery cell is calculated based on the second charging time and the mapping equation.

[0006] The lithium-ion battery cell CB value detection method according to the first aspect of this application has at least the following beneficial effects: It obtains the CB values ​​of several sample cells, and during capacity grading, charges each sample cell with the same first voltage at a constant voltage, recording the first charging time corresponding to each sample cell. Based on the CB value of each sample cell and its corresponding first charging time, it establishes a mapping equation between the CB value and the first charging time of the cell. It then charges the cell under test with the first voltage at a constant voltage to obtain the second charging time of the cell under test. Based on the second charging time and the mapping equation, it calculates the CB value of the cell under test. This application does not require calculating data such as the cell's capacity, internal resistance, K-value, and mass; it only needs to obtain the charging time corresponding to the cell to be tested to conveniently and quickly find its corresponding CB value, thus improving the detection efficiency of the cell CB value.

[0007] According to some embodiments of the first aspect of this application, obtaining the CB values ​​of a plurality of sample cells includes: Obtain the positive electrode mass and negative electrode mass of several sample cells; The CB value of each sample cell is calculated based on the mass of the positive electrode and the mass of the negative electrode.

[0008] According to some embodiments of the first aspect of this application, calculating the CB value of each sample cell based on the mass of the positive electrode and the mass of the negative electrode includes: Obtain the specific capacity of the positive electrode active material, the content ratio of the positive electrode active material, the positive electrode coating area, the mass of the positive electrode copper foil, the specific capacity of the negative electrode active material, the content ratio of the negative electrode active material, the negative electrode coating area, and the mass of the negative electrode copper foil of the sample cell; The CB value of each sample cell is calculated based on the specific capacity of the positive electrode active material, the content ratio of the positive electrode active material, the coating area of ​​the positive electrode, the coating mass of the positive electrode, the mass of the positive electrode copper foil, the specific capacity of the negative electrode active material, the content ratio of the negative electrode active material, the coating area of ​​the negative electrode, the mass of the negative electrode copper foil, and the coating mass of the negative electrode.

[0009] According to some embodiments of the first aspect of this application, establishing a mapping equation based on the CB value of the sample battery cell and the first charging time includes: The CB values ​​of all the sample cells and the corresponding first charging time are input into a preset univariate linear regression model for regression analysis to obtain the linear relationship between the CB value and the charging time of the cells. Based on the linear relationship, establish the mapping equation.

[0010] According to some embodiments of the first aspect of this application, after the step of calculating the CB value of the detected battery cell based on the second charging time and the mapping equation, the method further includes: When the CB value of the tested cell is greater than the preset upper limit threshold, the corresponding tested cell is marked as a defective product.

[0011] According to some embodiments of the first aspect of this application, after the step of calculating the CB value of the detected battery cell based on the second charging time and the mapping equation, the method further includes: When the CB value of the tested cell is less than a preset lower threshold, the corresponding tested cell is marked as a defective product.

[0012] According to some embodiments of the first aspect of this application, it also includes: Perform preset performance tests on each of the sample cells and generate test performance results; When the test performance result corresponding to the sample cell does not match the preset theoretical performance result, the corresponding sample cell is marked as a risk cell; wherein, the risk cell is used to characterize that the CB value and the first charging time of the corresponding sample cell cannot be used as sample data for establishing the mapping relationship equation.

[0013] According to some embodiments of the first aspect of this application, the step of performing a preset performance test on each of the sample cells and generating performance test results includes: Each of the sample cells was subjected to several hot box tests at different temperatures, and the hot box test results were generated. Each of the sample cells was subjected to a high-temperature cycling test, and the test cycle results were generated. Correspondingly, when the test performance result corresponding to the sample cell does not match the preset theoretical performance result, the corresponding sample cell is marked as a risk cell, including: If the test chamber result corresponding to the sample cell does not match the preset theoretical chamber result, the corresponding sample cell will be marked as a risk cell. If the test cycle result corresponding to the sample cell does not match the preset theoretical cycle result, the corresponding sample cell is marked as a risk cell.

[0014] Secondly, this application also provides a lithium-ion cell CB value detection device, comprising: at least one memory; at least one processor; at least one program; the program is stored in the memory, and the processor executes at least one of the programs to implement the lithium-ion cell CB value detection method as described in any embodiment of the first aspect.

[0015] The lithium-ion battery cell CB value detection device according to the second aspect of this application has at least the following beneficial effects: It acquires the CB values ​​of several sample cells, and during capacity grading, charges each sample cell with the same first voltage at a constant voltage, recording the first charging time corresponding to each sample cell. Based on the CB value of each sample cell and its corresponding first charging time, it establishes a mapping equation between the CB value and the first charging time of the cell. It then charges the cell under test with the first voltage at a constant voltage to obtain the second charging time of the cell under test. Based on the second charging time and the mapping equation, it calculates the CB value of the cell under test. This application does not require calculating data such as the cell's capacity, internal resistance, K-value, and mass; it only needs to acquire the charging time corresponding to the cell to be tested to conveniently and quickly find its corresponding CB value, thus improving the detection efficiency of the cell CB value.

[0016] Thirdly, this application also provides a computer-readable storage medium storing computer-executable signals for performing a lithium-ion cell CB value detection method as described in any embodiment of the first aspect.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] Additional aspects and advantages of this application will become apparent and readily understood in conjunction with the following description of the embodiments, in which: Figure 1 This is a flowchart of a method for detecting the CB value of a lithium-ion battery cell according to an embodiment of this application; Figure 2 This is a flowchart of a method for detecting the CB value of a lithium-ion battery cell according to another embodiment of this application; Figure 3 This is a flowchart of a method for detecting the CB value of a lithium-ion battery cell according to another embodiment of this application; Figure 4 This is a flowchart of a method for detecting the CB value of a lithium-ion battery cell according to another embodiment of this application; Figure 5 This is a flowchart of a method for detecting the CB value of a lithium-ion battery cell according to another embodiment of this application; Figure 6 This is a flowchart of a method for detecting the CB value of a lithium-ion battery cell according to another embodiment of this application; Figure 7 This is a flowchart of a method for detecting the CB value of a lithium-ion battery cell according to another embodiment of this application; Figure 8 This is a flowchart of a method for detecting the CB value of a lithium-ion battery cell according to another embodiment of this application; Figure 9 This is a schematic diagram of the mapping relationship equation according to an embodiment of this application; Figure 10 This is a summary diagram of the detection results of the CB value of the battery cell according to one embodiment of this application; Figure 11 This is a schematic diagram of the theoretical hot box results of one embodiment of this application; Figure 12 This is a schematic diagram of the theoretical cycle result of one embodiment of this application. Detailed Implementation

[0019] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0020] In the description of this application, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0021] In the description of this application, the use of "first" and "second" is for the purpose of distinguishing technical features only, and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0022] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0023] Firstly, referring to Figure 1 This application provides a method for detecting the CB value of a lithium-ion battery cell, including but not limited to the following steps S110 to S150: Step S110: Obtain the CB values ​​of several sample cells; Step S120: Charge the sample cells with a constant voltage using a first voltage, and record the first charging time for each sample cell; Step S130: Establish a mapping equation based on the CB value of the sample cell and the corresponding first charging time; Step S140: Charge the test cell with a constant voltage using a first voltage to obtain the second charging time of the test cell; Step S150: Calculate the CB value of the tested cell based on the second charging time and mapping relationship equation.

[0024] In steps S110 to S150 of this application embodiment, the CB values ​​of several sample cells are obtained. During capacity assessment, each sample cell is charged with a constant voltage using the same first voltage, and the first charging time corresponding to each sample cell is recorded. Based on the CB value of each sample cell and its corresponding first charging time, a mapping equation between the CB value and the first charging time of the cell is established. The cell to be tested is charged with a constant voltage using the first voltage to obtain the second charging time of the cell to be tested. Based on the second charging time and the mapping equation, the CB value of the cell to be tested is calculated. This application does not require calculating data such as the capacity, internal resistance, K value, and mass of the cell. It only needs to obtain the charging time corresponding to the cell to be tested to conveniently and quickly find its corresponding CB value, thereby improving the detection efficiency of the cell CB value.

[0025] It should be noted that in step S110, this application uses 30 battery cells as sample cells and obtains the CB values ​​of the 30 sample cells. The sample cells are charged at a constant voltage, for example, at a constant voltage of 0.5C until the cutoff current. The cutoff current can be 0.02C or other predetermined currents. This application does not limit this. The charging time of each sample cell is recorded, which is the first charging time in step S120. Based on the data set of the 30 sets of cell CB values ​​and the corresponding first charging time, a mapping relationship equation is established.

[0026] Reference Figure 2 It is understood that step S110 may include, but is not limited to, the following steps: Step S210: Obtain the mass of the positive electrode and the mass of the negative electrode of several sample cells; Step S220: Calculate the CB value of each sample cell based on the mass of the positive electrode and the mass of the negative electrode.

[0027] The masses of the positive and negative electrodes of all sample cells were measured manually. The mass of the positive electrode was obtained by subtracting the mass of the positive electrode copper foil from the total mass of the positive electrode, and similarly, the mass of the negative electrode was obtained by subtracting the mass of the negative electrode copper foil from the total mass of the negative electrode. This application does not impose any limitations on this method. The CB values ​​corresponding to the 30 sample cells were calculated using the masses of the positive and negative electrodes. It should be noted that the CB values ​​between the sample cells need to exhibit a certain gradient change in order to establish a more accurate mapping equation.

[0028] Reference Figure 3 It is understood that step S220 may include, but is not limited to, the following steps: Step S310: Obtain the specific capacity of positive electrode active material, the content ratio of positive electrode active material, the coating area of ​​positive electrode, the mass of positive electrode copper foil, the specific capacity of negative electrode active material, the content ratio of negative electrode active material, the coating area of ​​negative electrode, and the mass of negative electrode copper foil of the sample cell. Step S320: Calculate the CB value of each sample cell based on the specific capacity of the positive electrode active material, the content ratio of the positive electrode active material, the positive electrode coating area, the positive electrode coating mass, the positive electrode copper foil mass, the specific capacity of the negative electrode active material, the content ratio of the negative electrode active material, the negative electrode coating area, the negative electrode copper foil mass, and the negative electrode coating mass.

[0029] In step S320, the CB value of the sample cell = positive electrode capacity per unit area ÷ negative electrode capacity per unit area, where the positive electrode capacity per unit area = positive active material specific capacity × positive active material content ratio × positive electrode coating mass ÷ positive electrode coating area, and the negative electrode capacity per unit area = negative active material specific capacity × negative active material content ratio × negative electrode coating mass ÷ negative electrode coating area, where the positive electrode coating mass = positive electrode sheet mass - positive electrode copper foil mass, and the negative electrode coating mass = negative electrode sheet mass - negative electrode copper foil mass.

[0030] Reference Figure 4 It is understood that step S130 may include, but is not limited to, the following steps: Step S410: Input the CB value of all sample cells and the corresponding first charging time into a preset univariate linear regression model for regression analysis to obtain the linear relationship between the CB value of the cells and the charging time. Step S420: Establish the mapping equation based on the linear relationship.

[0031] There is a linear relationship between the CB value of a battery cell and its charging time. Therefore, by inputting the CB values ​​and corresponding first charging times of 30 sample battery cells into a univariate linear regression model for regression analysis, a mapping equation was established based on their linear relationship. Specifically, refer to... Figure 9 A mapping equation is established between the CB value of the battery cell and the charging time. This mapping equation represents the constant voltage charging time as 183.12 × CB value - 158.53. The mapping equation is different for different types of battery cells. Therefore, the above embodiment is only the mapping equation between the CB value and the charging time for one type of battery cell. For different types of battery cells, it is necessary to recalculate and establish the mapping equation between the CB value and the charging time using several sets of sample battery cells.

[0032] Reference Figure 5It is understood that after step S150, the following steps may be included, but are not limited to: Step S510: When the CB value of the tested cell is greater than the preset upper limit threshold, the corresponding tested cell is marked as a defective product.

[0033] It should be noted that if the CB value of a battery cell is too high, its positive electrode potential will be too high, resulting in poor high-temperature performance of the cell. This usually leads to the detachment of the positive electrode powder from the foil and the yellowing of the separator. Therefore, cells with a CB value greater than the preset upper limit threshold are removed to avoid affecting the quality of the battery. In other words, cells marked as defective are removed to improve the quality of the cells leaving the factory.

[0034] Reference Figure 6 It is understood that after step S150, the following steps may be included, but are not limited to: Step S610: When the CB value of the tested cell is less than the preset lower threshold, the corresponding tested cell is marked as a defective product.

[0035] It should be noted that if the CB value of a battery cell is too low, the excess Li released will provide a Li source for the deposition of lithium salt on the negative electrode surface. The continuous deposition of lithium salt leads to cycle failure. Therefore, battery cells with a CB value lower than the preset lower threshold are removed to avoid affecting the quality of battery use. In other words, battery cells marked as defective are removed to improve the quality of battery cells leaving the factory.

[0036] It should be noted that the CB value of each tested cell can be statistically analyzed, and the testing order of the cells can be recorded to form a statistical chart of the CB values ​​of all tested cells, for reference. Figure 10 The detection cells corresponding to CB values ​​greater than the upper threshold or less than the lower threshold can be quickly identified from the figure. The upper and lower thresholds are different for different types of cells, and this application does not limit them.

[0037] Reference Figure 7 It is understood that the method for detecting the CB value of lithium-ion cells provided in this application also includes, but is not limited to, the following steps: Step S710: Perform preset performance tests on each sample cell and generate test performance results; Step S720: When the test performance result of the sample cell does not match the preset theoretical performance result, the corresponding sample cell is marked as a risk cell; wherein, the CB value and first charging time of the risk cell are used to characterize the corresponding sample cell and cannot be used as sample data for establishing the mapping relationship equation.

[0038] The CB value and corresponding first charging time of the sample cells serve as the basis for establishing the mapping equation. If some of the sample cells are risky cells, it will affect the accuracy of the mapping equation. By performing preset performance tests on each sample cell and comparing the test performance results with the preset theoretical performance results, risky cells that do not meet the theoretical performance results are eliminated, thereby improving the accuracy of establishing the mapping equation.

[0039] Reference Figure 8 It is understood that step S710 includes, but is not limited to, the following steps: Step S810: Perform several hot box tests at different temperatures on each sample cell and generate the hot box test results; Step S820: Perform high-temperature cycling tests on each sample cell and generate test cycle results; Step S830: When the test hot box result corresponding to the sample cell does not match the preset theoretical hot box result, the corresponding sample cell is marked as a risk cell; Step S840: When the test cycle result corresponding to the sample cell does not match the preset theoretical cycle result, the corresponding sample cell is marked as a risk cell.

[0040] The higher the CB value of a battery cell, the worse its high-temperature performance. Therefore, each sample battery cell was subjected to hot box testing at different temperatures and high-temperature cycling testing at high temperatures. Figure 11 As shown, Figure 11 This is a schematic diagram of the theoretical hot box test results. In the hot box test, as the temperature increases, the sample cells will successively fail the test as the CB value decreases. Figure 12 As shown, Figure 12 This diagram illustrates the theoretical cycling results. In high-temperature cycling tests at 45°C, cells with higher CB values ​​have fewer cycle times. By conducting hot-box tests and high-temperature cycling tests on each sample cell, risky cells that do not meet the theoretical performance results are eliminated, thus improving the accuracy of the mapping equation.

[0041] Secondly, this application also provides a lithium-ion cell CB value detection device, comprising: at least one memory, at least one processor and at least one program, wherein the program is stored in the memory, and the processor executes one or more programs to implement the above-described lithium-ion cell CB value detection method.

[0042] The method involves acquiring the CB values ​​of several sample cells and charging each sample cell at a constant voltage using the same first voltage during capacity assessment. The first charging time for each sample cell is recorded. Based on the CB value and its corresponding first charging time, a mapping equation is established between the CB value and the first charging time. The test cell is then charged at a constant voltage using the first voltage to obtain its second charging time. The CB value of the test cell is calculated based on the second charging time and the mapping equation. This method eliminates the need to calculate data such as cell capacity, internal resistance, K-value, and mass. It allows for quick and easy identification of the CB value based solely on the charging time of the cell to be tested, thus improving the efficiency of CB value detection.

[0043] Processors and memory can be connected via a bus or other means.

[0044] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and signals, such as the program instructions / signals corresponding to the processing module in the embodiments of this application. The processor executes various functional applications and data processing by running the non-transitory software programs, instructions, and signals stored in the memory, thereby implementing the lithium-ion battery cell CB value detection method of the above method embodiments.

[0045] The memory may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data related to the lithium-ion cell CB value detection method described above. Furthermore, the memory may include high-speed random access memory and non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processing module via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0046] One or more signals are stored in a memory, and when executed by one or more processors, the lithium-ion cell CB value detection method described in any of the above method embodiments is executed. For example, the method described above is executed. Figure 1 Method steps S110 to S150 in the text Figure 2 Method steps S210 to S220, Figure 3 Method steps S310 to S320 in the text Figure 4 Method steps S410 to S420 in the text Figure 5 Method steps S510, Figure 6 Method steps S610, Figure 7Method steps S710 to S720 and Figure 8 Method steps S810 to S840.

[0047] Fifthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions that are executed by one or more processors, causing the one or more processors to perform the lithium-ion cell CB value detection method described in the above method embodiments. For example, performing the above-described... Figure 1 Method steps S110 to S150 in the text Figure 2 Method steps S210 to S220, Figure 3 Method steps S310 to S320 in the text Figure 4 Method steps S410 to S420 in the text Figure 5 Method steps S510, Figure 6 Method steps S610, Figure 7 Method steps S710 to S720 and Figure 8 Method steps S810 to S840.

[0048] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and 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.

[0049] Based on the above description of the embodiments, those skilled in the art will understand that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable signals, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible by a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable signals, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specifically," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0051] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

Claims

1. A method for detecting the CB value of a lithium-ion battery cell, characterized in that, include: Obtain the CB values ​​of several sample cells; The sample cells are charged at a constant voltage using a first voltage, and the first charging time for each sample cell is recorded; wherein, the first charging time is the time taken for the sample cell to reach the preset cutoff current from the start of constant voltage charging. A mapping equation is established based on the CB value of the sample battery cell and the corresponding first charging time; The test cell is charged at a constant voltage using the first voltage to obtain a second charging time for the test cell; wherein, the second charging time is the time taken for the test cell to reach a preset cutoff current from the start of constant voltage charging. The CB value of the detected battery cell is calculated based on the second charging time and the mapping equation.

2. The method for detecting the CB value of a lithium-ion battery cell according to claim 1, characterized in that, The process of obtaining the CB values ​​of several sample cells includes: Obtain the positive electrode mass and negative electrode mass of several sample cells; The CB value of each sample cell is calculated based on the mass of the positive electrode and the mass of the negative electrode.

3. The method for detecting the CB value of a lithium-ion battery cell according to claim 1, characterized in that, The step of establishing a mapping equation based on the CB value of the sample battery cell and the first charging time includes: The CB values ​​of all the sample cells and the corresponding first charging time are input into a preset univariate linear regression model for regression analysis to obtain the linear relationship between the CB value and the charging time of the cells. Based on the linear relationship, establish the mapping equation.

4. The method for detecting the CB value of a lithium-ion battery cell according to claim 1, characterized in that, After the step of calculating the CB value of the detected battery cell based on the second charging time and the mapping equation, the method further includes: When the CB value of the tested cell is greater than the preset upper limit threshold, the corresponding tested cell is marked as a defective product.

5. The method for detecting the CB value of a lithium-ion battery cell according to claim 1 or 4, characterized in that, After the step of calculating the CB value of the detected battery cell based on the second charging time and the mapping equation, the method further includes: When the CB value of the tested cell is less than a preset lower threshold, the corresponding tested cell is marked as a defective product.

6. The method for detecting the CB value of a lithium-ion battery cell according to claim 1, characterized in that, Also includes: Perform preset performance tests on each of the sample cells and generate test performance results; When the test performance result corresponding to the sample cell does not match the preset theoretical performance result, the corresponding sample cell is marked as a risk cell; wherein, the risk cell is used to characterize that the CB value and the first charging time of the corresponding sample cell cannot be used as sample data for establishing the mapping relationship equation.

7. The method for detecting the CB value of a lithium-ion battery cell according to claim 6, characterized in that, The step of performing a preset performance test on each of the sample cells and generating test performance results includes: Each of the sample cells was subjected to several hot box tests at different temperatures, and the hot box test results were generated. Each of the sample cells was subjected to a high-temperature cycling test, and the test cycle results were generated. Correspondingly, when the test performance result corresponding to the sample cell does not match the preset theoretical performance result, the corresponding sample cell is marked as a risk cell, including: If the test chamber result corresponding to the sample cell does not match the preset theoretical chamber result, the corresponding sample cell will be marked as a risk cell. If the test cycle result corresponding to the sample cell does not match the preset theoretical cycle result, the corresponding sample cell is marked as a risk cell.

8. A device for detecting the CB value of a lithium-ion battery cell, characterized in that, include: At least one memory; At least one processor; At least one program; The program is stored in the memory, and the processor executes at least one of the programs to implement the lithium-ion cell CB value detection method as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable signals for performing the lithium-ion cell CB value detection method as described in any one of claims 1 to 7.

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