Battery Detection Method, Device, Electronic Device, Storage Medium, and Computer Program Product

Abstract

The present application discloses a battery detection method, device, electronic device, storage medium and computer program product. Among them, the method includes: for each of a plurality of battery cells, obtaining a first swelling force value and a second swelling force value of each battery cell during the production process; the first swelling force value is the peak swelling force when the battery cell is within a first state of charge range, the second swelling force value is the peak swelling force when the battery cell is within a second state of charge range, and the maximum state of charge within the first state of charge range is less than the minimum state of charge within the second state of charge range; based on the first swelling force value and the second swelling force value corresponding to each battery cell, determining whether there is an abnormal battery cell among the plurality of battery cells. In the embodiments of the present application, it is possible to effectively and accurately identify the battery cells with abnormal swelling force in mass-produced battery cells, improving the safety of battery production.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and in particular, to a battery detection method, device, electronic device, storage medium, and computer program product. Background Art

[0002] Lithium batteries have the advantages of high power density, high energy density, long cycle life, high output voltage, and environmental friendliness, and are widely used in new energy vehicles, consumer electronics, energy storage systems, and other fields.

[0003] As the degree of cycle aging (or storage aging) of lithium batteries increases, the internal solid electrolyte interface (SEI) layer will experience a process of destruction / repair, the SEI layer will thicken, and the positive and negative electrode plates will rebound, all of which will increase the swelling force of the lithium battery cell; when this increase in swelling force reaches a certain range, it will affect the structure of the battery module, such as safety hazards such as decreased battery performance, cracked battery housing, electrolyte leakage, and internal short circuit of the battery.

[0004] Due to possible abnormal incoming materials, abnormal environmental water content, and abnormal production process parameters during the production process, the swelling force of the battery cell of the battery product may exceed the safety range. In related technologies, a prediction model is usually used to identify a small number of abnormal battery cells with swelling force exceeding the safety range during the R & D stage; however, the above method cannot effectively and accurately identify the battery cells with abnormal swelling force in mass-produced battery cells.

[0005] The above statements are only used to provide background technical information related to this application, and do not necessarily constitute prior art. Summary of the Invention

[0006] In view of the above problems, this application provides a battery detection method, device, electronic device, storage medium, and computer program product, which can solve the technical problem that in related technologies, it is impossible to effectively and accurately identify the battery cells with abnormal swelling force in mass-produced battery cells.

[0007] In a first aspect, this application provides a battery detection method, including: for each of a plurality of battery cells, obtaining a first swelling force value and a second swelling force value of each battery cell during the production process; the first swelling force value is the peak swelling force of the battery cell within a first state of charge range, the second swelling force value is the peak swelling force of the battery cell within a second state of charge range, and the maximum state of charge within the first state of charge range is less than the minimum state of charge within the second state of charge range, obtaining the swelling force values of each battery cell under different states of charge;

[0008] Based on the first expansion force value and the second expansion force value corresponding to each battery cell, determine whether there is an abnormal battery cell among the multiple battery cells.

[0009] In the technical solution of the embodiment of the present invention, for each of the multiple battery cells during mass production, by obtaining the expansion force values of each battery cell under different state of charge; based on the expansion force values corresponding to each battery cell, determine whether there is an abnormal battery cell among the multiple battery cells. Compared with the method of usually using a prediction model to identify abnormal battery cells in the related art, the present application can not only accurately and effectively identify the battery cells with abnormal expansion force in mass-produced battery cells, reduce the dependence of the detection process on the type and structure of the battery cells, but also has small limitations and high universality.

[0010] In some embodiments, the determining whether there is an abnormal battery cell among the multiple battery cells based on the first expansion force value and the second expansion force value corresponding to each battery cell includes: obtaining the difference between the first expansion force value and the second expansion force value corresponding to each battery cell; in the case that there is an expansion force outlier in the difference set composed of the differences, determine that there is an abnormal battery cell among the multiple battery cells.

[0011] By obtaining the difference between the first expansion force value and the second expansion force value corresponding to the battery cell, and in the case that there is an expansion force outlier in the difference set composed of the differences, the embodiment of the present application can not only timely discover and eliminate abnormal battery cells, but also reduce the detection error in the process of obtaining the first expansion force value and the second expansion force value, and significantly improve the accuracy of identifying the battery cells with abnormal expansion force in mass-produced battery cells.

[0012] In some embodiments, the determining whether there is an abnormal battery cell among the multiple battery cells based on the first expansion force value and the second expansion force value corresponding to each battery cell includes:

[0013] Obtain the first weight coefficient corresponding to the first expansion force value of each battery cell, and the second weight coefficient corresponding to the second expansion force value of each battery cell;

[0014] Determine the first product of the first expansion force value and the first weight coefficient of each battery cell, and the second product of the second expansion force value and the second weight coefficient of each battery cell;

[0015] Calculate the difference between the first product and the second product corresponding to each battery cell;

[0016] In the case that there is an expansion force outlier in the difference set composed of the differences, determine that there is an abnormal battery cell among the multiple battery cells.

[0017] In the embodiments of the present application, by analyzing the swelling force outliers in multiple battery cells through weighted difference, not only can abnormal battery cells be identified more accurately, avoiding misjudgment caused by fluctuations in a single swelling force value, but also the weight coefficients of the first swelling force value and the second swelling force value can be adjusted according to actual needs, improving the flexibility and universality of detection.

[0018] In some embodiments, obtaining the first swelling force value and the second swelling force value of each battery cell includes:

[0019] Obtaining the first swelling force value of each battery cell based on the first formation process in the production process; the first formation process is used to make the battery cell in the first state of charge range;

[0020] Obtaining the second swelling force value of each battery cell based on the capacity process in the production process; the capacity process is used to make the battery cell in the second state of charge range.

[0021] In the embodiments of the present application, by monitoring the swelling force value of each battery cell in real time in the battery production line, not only can abnormal battery cells be found accurately and in a timely manner, reducing the output of defective products, but also the quality and safety of battery cell production can be improved.

[0022] In some embodiments, obtaining the first swelling force value of each battery cell based on the first formation process in the production process includes:

[0023] Let each battery cell stand for a first preset duration, and perform constant current charging on each battery cell at a first charging rate for a second preset duration;

[0024] Let each battery cell stand for the first preset duration, perform constant current charging on each battery cell at the first charging rate for a third preset duration so that each battery cell reaches a second state of charge from the first state of charge, and let each battery cell stand for the first preset duration;

[0025] Perform constant current charging on each battery cell at a second charging rate for a fourth preset duration; let each battery cell stand for the first preset duration;

[0026] Perform constant current charging on the battery cell at the second charging rate for the fourth preset duration so that each battery cell reaches a third state of charge from the second state of charge, and let each battery cell stand for the first preset duration;

[0027] Obtain the first swelling force value corresponding to each battery cell between the first state of charge and the third state of charge.

[0028] By means of staged static placement and charging, the embodiments of the present application can accurately capture the changes in the swelling force of the battery cells under different state of charge (SOC). Obtaining the swelling force data during the formation process helps to early identify potential abnormalities of the battery cells, and based on the actual measurement data, it can also provide support for the production quality control and process optimization of the battery cells.

[0029] In some embodiments, obtaining the second swelling force value of each battery cell based on the capacity process in the production process includes:

[0030] Static-place each battery cell for a first preset duration, and perform constant-current charging on each battery cell at a third charging rate until each battery cell reaches the maximum charging voltage;

[0031] Perform constant-voltage charging on each battery cell at the maximum charging voltage until the charging current drops to a fourth charging rate to make each battery cell reach a fully charged state;

[0032] Obtain the corresponding second swelling force value of each battery cell in the capacity process.

[0033] By means of staged static placement and charging, the embodiments of the present application can accurately capture the changes in the swelling force of the battery cells under different state of charge (SOC). Obtaining the swelling force data during the capacity process helps to early identify potential abnormalities of the battery cells, and based on the actual measurement data, it can also provide support for the production quality control and process optimization of the battery cells.

[0034] In some embodiments, obtaining the first swelling force value and the second swelling force value of each battery cell further includes:

[0035] Obtain the first swelling force value and the second swelling force value of each battery cell based on a second formation process; the second formation process is used to make each battery cell reach a fourth state of charge from a first state of charge, and the second formation process includes the steps corresponding to the first formation process, the steps corresponding to the capacity process, and the operation steps of discharging each battery cell to a fifth state of charge for aging.

[0036] The embodiments of the present application obtain the first swelling force value and the second swelling force value of the battery cells through the second formation process, and combined with the aging operation, can comprehensively evaluate the swelling force characteristics of the battery cells under different states of charge and use conditions. This method not only improves the detection accuracy of abnormal battery cells, but also provides an important basis for the production quality control and process optimization of the battery cells.

[0037] Second aspect, an embodiment of the present invention provides a battery detection device, including: an acquisition unit configured to acquire, for each of a plurality of battery cells, a first swelling force value and a second swelling force value during the production process of each battery cell; the first swelling force value is the peak swelling force when the battery cell is within a first state of charge range, and the second swelling force value is the peak swelling force when the battery cell is within a second state of charge range, and the maximum state of charge within the first state of charge range is less than the minimum state of charge within the second state of charge range; a determination unit configured to determine whether there is an abnormal battery cell among the plurality of battery cells based on the first swelling force value and the second swelling force value corresponding to each battery cell.

[0038] Third aspect, an embodiment of the present application further provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the battery detection method described in the first aspect is implemented.

[0039] Fourth aspect, an embodiment of the present application further provides a computer-readable storage medium storing a computer program, which when executed by a processor, implements the battery detection method described in the first aspect.

[0040] Fifth aspect, an embodiment of the present application further provides a computer program product including a computer program, which when executed by a processor, implements the battery detection method described in the first aspect.

[0041] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features, and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically described below. Description of the Drawings

[0042] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. And in all the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0043] Figure 1 It is a flowchart of a battery detection method provided by an embodiment of the present application;

[0044] Figure 2 It is a flowchart of another battery detection method provided by an embodiment of the present application;

[0045] Figure 3 It is a schematic diagram of a battery cell swelling force curve provided by an embodiment of the present application;

[0046] Figure 4 Flow chart of another battery detection method provided by an embodiment of the present application;

[0047] Figure 5 It is a flow chart of another battery detection method provided by an embodiment of the present application;

[0048] Figure 6 It is a schematic diagram of the expansion force difference distribution of a battery detection method provided by an embodiment of the present application;

[0049] Figure 7 It is a schematic structural diagram of a battery detection device provided by an embodiment of the present application;

[0050] Figure 8 It is a schematic structural diagram of an electronic device provided by an embodiment of the present application. Detailed implementation manners

[0051] Hereinafter, embodiments of the technical solutions of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present application more clearly, and thus are only examples and cannot be used to limit the protection scope of the present application.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0053] In the description of the embodiments of the present invention, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, "a plurality of" means more than two unless otherwise specifically defined.

[0054] Referring to "embodiment" herein means that a specific feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0055] In the description of the embodiments of the present invention, the term "and / or" is merely a description of the association relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, in this text, the character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0056] In the description of the embodiments of the present invention, the term "a plurality of" refers to two or more (including two). Similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of sheets" refers to two or more sheets (including two sheets).

[0057] Currently, power batteries are more and more widely used. Power batteries are not only applied to energy storage power systems such as hydraulic, thermal, wind, and solar power stations, but also widely used in electric transportation tools such as electric bicycles, electric motorcycles, and electric vehicles, as well as in multiple fields such as military equipment and aerospace. In fields such as electric transportation supply, military equipment, and aerospace, power is usually provided by batteries.

[0058] Among various types of power batteries, due to the advantages of lithium batteries such as high power density, high energy density, long cycle life, high output voltage, and environmental friendliness, they are widely used in new energy vehicles, consumer electronics, energy storage systems and other fields. How to improve the charging speed of lithium batteries while ensuring the charging performance has become a current research hotspot.

[0059] As the degree of cycle aging (or storage aging) of lithium batteries increases, a process of destruction / repair of the solid electrolyte interface layer (SEI) will occur inside them. The SEI layer will thicken, and the positive and negative electrode plates will show a rebound phenomenon, all of which will increase the swelling force of the lithium battery cell core; when this increase in swelling force reaches a certain range, it will affect the structure of the battery module, such as safety hazards such as a decline in battery performance, a cracked battery shell, electrolyte leakage, and internal short circuit of the battery. Due to possible abnormal incoming materials, abnormal environmental water content, abnormal production process parameters, etc. during the production process, the swelling force of the battery cell core of the battery product may exceed the safe range.

[0060] In related technologies, a prediction model is usually used to identify abnormal battery cells with a swelling force exceeding the safe range that occur in small quantities during the R & D stage. The above method is limited to the R & D stage of the battery, testing the R & D battery cells (generally only testing a few battery cells) and establishing a certain prediction model; this method cannot take into account the possible abnormal situations of mass-produced battery cells.

[0061] In view of the above problems in the related art, some embodiments of the present application provide a battery detection method, apparatus, electronic device, and storage medium. The method includes: for each of a plurality of battery cells, obtaining the swelling force value of each battery cell at different state of charge levels; and determining whether there is an abnormal battery cell among the plurality of battery cells based on the swelling force value corresponding to each battery cell.

[0062] In the technical solution of the embodiments of the present invention, for each of a plurality of battery cells during mass production, by obtaining the swelling force value of each battery cell at different state of charge levels; and determining whether there is an abnormal battery cell among the plurality of battery cells based on the swelling force value corresponding to each battery cell. Compared with the related art in which a prediction model is usually used to identify abnormal battery cells, the present application can not only accurately and effectively identify the battery cells with abnormal swelling force in mass-produced battery cells, reduce the dependence of the detection process on the type and structure of the battery cells, but also has small limitations and high universality.

[0063] The following specifically describes the specific process of the battery detection method of the present application through specific embodiments. Refer to Figure 1 the flowchart of the battery detection method shown in the figure, and the method specifically includes the following steps:

[0064] S102, for each of a plurality of battery cells, obtaining the swelling force value of each battery cell at different state of charge levels;

[0065] S104, determining whether there is an abnormal battery cell among the plurality of battery cells based on the swelling force value corresponding to each battery cell.

[0066] Specifically, in the embodiments of the present invention, the above-mentioned battery cell types may be, for example, ternary lithium battery cells or lithium iron phosphate battery cells. In order to obtain the swelling force change curve of each battery cell during the battery production process, it is necessary to monitor the swelling force of the battery cells during the production process with a fixture. For example, in the formation process, when the battery cells are formed with a fixture, the initial force of the fixture for each battery cell (the fixture force applied to each battery cell before formation) ranges from 500 N to 2000 N, and the optimal value is 1000 N. Based on the above fixture, the swelling force value corresponding to each battery cell at different state of charge (SOC) levels during the production process can be obtained.

[0067] In one example, by obtaining the swelling force value of each battery cell at different state of charge levels, and then using the standard deviation or the local outlier factor detection algorithm to analyze whether there are abnormal points in the battery cell swelling force data. If the number of abnormal points is greater than a preset value, it can be determined whether there is an abnormal battery cell among the plurality of battery cells.

[0068] By obtaining the swelling force values of each battery cell at different states of charge, the normal range of the swelling force of the battery cell can be predicted. When the swelling force of a certain battery cell exceeds this normal range, it can be determined as abnormal. Thus, it can be determined whether there is an abnormal battery cell among the multiple battery cells.

[0069] In addition, it is also possible to monitor the change of the swelling force growth rate of the above-mentioned multiple battery cells to determine the abnormal battery cell; for example, when the growth rate of the swelling force of a certain battery cell exceeds the normal range and lasts for a long time, it can be determined that this battery cell is an abnormal battery cell.

[0070] In the technical solution of the embodiment of the present invention, for each of the multiple battery cells in the mass production process, by obtaining the swelling force values of each battery cell at different states of charge; based on the swelling force values corresponding to each battery cell, it is determined whether there is an abnormal battery cell among the multiple battery cells. Compared with the method of usually using a prediction model to identify abnormal battery cells in the related art, the present application can not only accurately and effectively identify the battery cells with abnormal swelling force in the mass-produced battery cells, reduce the dependence of the detection process on the type and structure of the battery cells, and has small limitations and high universality.

[0071] In one or more embodiments of the present application, as Figure 2 shown, the above battery detection method includes the following steps:

[0072] S202, for each of the multiple battery cells, obtain the first swelling force value and the second swelling force value of each battery cell; the first swelling force value is the peak value of the swelling force when the battery cell is within the first state of charge range, and the second swelling force value is the peak value of the swelling force when the battery cell is within the second state of charge range, and the maximum state of charge within the first state of charge range is less than the minimum state of charge within the second state of charge range;

[0073] S104, based on the swelling force values corresponding to each battery cell, determine whether there is an abnormal battery cell among the multiple battery cells.

[0074] Specifically, in the embodiment of the present application, as Figure 3 shown, each battery cell will correspond to different swelling force values at different states of charge during the charging process. According to the corresponding relationship between the state of charge and the swelling force value, the swelling force curve of each battery cell can be obtained.

[0075] During the charging stage of the lithium-ion battery, due to factors such as the formation of the SEI layer and the particle swelling caused by the intercalation of lithium into graphite, the swelling force of the battery cell will increase; combined with Figure 3 shown, among them, there will be a maximum point of the swelling force near 30% SOC, that is, the first swelling force value F1, and there is a maximum point of the swelling force near 95% SOC, that is, the second swelling force value F2.

[0076] When the battery cell is charged for the first time, the value of F2 is much greater than the value of F1. However, as the battery cell cycles or the degree of storage aging increases, both F1 and F2 will increase slowly, and the increase degree of F1 is greater than that of F2. When the lithium-ion battery ages, since the increase rate of the expansion force of the battery cell will become larger after reaching the expansion force inflection point, that is, there is a risk of failure of the expansion force of the battery cell during the warranty life. If the difference between F1 and F2 is larger, the state of health (SOH) of the battery cell when its expansion force reaches the expansion force inflection point is more lagged, that is, the risk of failure of the expansion force of the battery cell during the warranty life is lower. On the contrary, if the difference between F1 and F2 is smaller, the SOH of the battery cell when its expansion force reaches the expansion force inflection point is more advanced, that is, the risk of failure of the expansion force of the battery cell during the warranty life is higher.

[0077] In the embodiment of the present application, by obtaining the peak expansion force of the battery cell at different states of charge and determining the expansion force failure characteristic value according to its change rule, it can not only accurately and effectively identify the battery cells with abnormal expansion force in mass-produced battery cells, but also has high universality and early warning ability, ensuring the safety and reliability of the battery cell during use.

[0078] In one or more embodiments of the present application, as Figure 4 shown, the above battery detection method includes the following steps:

[0079] S402, for each battery cell in a plurality of battery cells, obtain a first expansion force value and a second expansion force value of each battery cell during the production process; the first expansion force value is the peak expansion force of the battery cell within a first state of charge range, the second expansion force value is the peak expansion force of the battery cell within a second state of charge range, and the maximum state of charge within the first state of charge range is less than the minimum state of charge within the second state of charge range.

[0080] S404, based on the first expansion force value and the second expansion force value corresponding to each battery cell, determine whether there are abnormal battery cells among the plurality of battery cells.

[0081] Specifically, in the embodiment of the present application, by performing multiple cycle charge and discharge operations on a plurality of battery cells during the production process, and then obtaining the first expansion force value and the second expansion force value of each battery cell in each cycle, a set of first expansion force values and a set of second expansion force values of each battery cell can be obtained based on each cycle. Based on each first expansion force value in the first expansion force set corresponding to each battery cell and each second expansion force value in the second expansion force set corresponding to each battery cell, it is possible to accurately determine whether there are abnormal battery cells among the plurality of battery cells.

[0082] In this application, at least one peak expansion force of the battery cell under different states of charge is obtained to determine the expansion force failure characteristic value of the battery cell. It can not only accurately and effectively identify the battery cells with abnormal expansion force in mass-produced battery cells, but also has high universality and early warning ability, ensuring the safety and reliability of the battery cells during use.

[0083] In one or more embodiments of this application, determining whether there are abnormal battery cells among the multiple battery cells based on the first expansion force value corresponding to each battery cell or the second expansion force value corresponding to each battery cell includes:

[0084] Determining that there are abnormal battery cells among the multiple battery cells if there are expansion force outliers in the first expansion force set composed of the first expansion force values corresponding to each battery cell, or if there are expansion force outliers in the second expansion force set composed of the second expansion force values corresponding to each battery cell.

[0085] Specifically, in the embodiments of this application, outlier detection is performed on the first expansion force set or the second expansion force set. For example, statistical analysis methods (such as box plots, standard deviations) or machine learning methods (such as the local outlier factor algorithm) are used to detect outliers in the set. If the expansion force value of a certain battery cell significantly deviates from the normal distribution range of the set, then this battery cell is determined to be an abnormal battery cell.

[0086] The embodiments of this application can accurately identify abnormal battery cells by analyzing the outliers in the peak expansion force set. During mass production, by real-time monitoring the expansion force outliers of the battery cells and timely discovering and removing the abnormal battery cells, the quality of battery production can be improved. And it is applicable to various types of battery cells, without being restricted by the battery cell material or structure.

[0087] In one or more embodiments of this application, as Figure 5 shown, the above battery detection method includes the following steps:

[0088] S402, for each of the multiple battery cells, obtain the first expansion force value and the second expansion force value of each battery cell during the production process; the first expansion force value is the peak expansion force when the battery cell is within the first state of charge range, the second expansion force value is the peak expansion force when the battery cell is within the second state of charge range, and the maximum state of charge within the first state of charge range is less than the minimum state of charge within the second state of charge range.

[0089] S504, obtain the difference between the first expansion force value and the second expansion force value corresponding to each battery cell;

[0090] S506, determine that there are abnormal battery cells among the multiple battery cells when there are expansion force outliers in the difference set composed of the differences.

[0091] Specifically, in the embodiments of the present application, during the process of obtaining the first expansion force value and the second expansion force value, since there will be deviations when the detection fixture detects the expansion force value of the battery cell, which does not match the actual expansion force, the present application determines that there are abnormal battery cells among the multiple battery cells by obtaining the difference between the first expansion force value and the second expansion force value corresponding to each battery cell, and detecting the outlier of the expansion force in the difference set formed by calculating the differences.

[0092] In one example, for instance, the detected first expansion force value is 800N (the true value is 1000N), and the second expansion force value is 1500N (the true value is 1700N). Then the difference between the detected first expansion force value of 800N and the second expansion force value of 1500N is the same as the difference corresponding to their true values. In this way, the accuracy of detecting abnormal battery cells can be significantly improved.

[0093] In a test example, obtain the first expansion force value F1, the second expansion force value F2 of all the battery cells produced on the same day, and the difference between F1 and F2; as Figure 6 shown, among the statistical data of F1 and F2 of the 200 monitored battery cells (1kgf = 1*9.8N), the battery cells with significantly lower differences (less than 78kgf) are abnormal battery cells, which have a relatively high risk of expansion force failure and should be treated as defective products during production.

[0094] The above step S402 has been described above and will not be elaborated here.

[0095] In the embodiments of the present application, by obtaining the difference between the first expansion force value and the second expansion force value corresponding to the battery cell, and detecting the outlier of the expansion force in the difference set formed by the difference, not only can abnormal battery cells be discovered and eliminated in a timely manner, but also the detection error in the process of obtaining the first expansion force value and the second expansion force value can be reduced, significantly improving the accuracy of identifying the battery cells with abnormal expansion force among the mass-produced battery cells.

[0096] In one or more embodiments of the present application, in some embodiments, determining whether there are abnormal battery cells among the multiple battery cells based on the first expansion force value corresponding to each battery cell and the second expansion force value corresponding to each battery cell includes:

[0097] Obtain the first weight coefficient corresponding to the first expansion force value of each battery cell, and the second weight coefficient corresponding to the second expansion force value of each battery cell;

[0098] Determine the first product of the first expansion force value and the first weight coefficient of each battery cell, and the second product of the second expansion force value and the second weight coefficient of each battery cell;

[0099] Calculate the difference between the first product and the second product corresponding to each of the battery cells.

[0100] In the case where a swelling force outlier appears in the set of differences formed by the differences, determine that there is an abnormal battery cell among the multiple battery cells.

[0101] The embodiment of the present application analyzes the swelling force outliers in multiple battery cells through weighted differences, which can not only more accurately identify abnormal battery cells and avoid misjudgment caused by fluctuations in a single swelling force value, but also adjust the weight coefficients of the first swelling force value and the second swelling force value according to actual needs, improving the flexibility and universality of detection.

[0102] In one or more embodiments of the present application, the obtaining of the first swelling force value and the second swelling force value of each battery cell includes:

[0103] Obtain the first swelling force value of each battery cell based on the first formation process in the production process; the first formation process is used to make the battery cell in the first state of charge range.

[0104] Obtain the second swelling force value of each battery cell based on the capacity process in the production process; the capacity process is used to make the battery cell in the second state of charge range.

[0105] It should be noted that the formation process in the embodiment of the present application can adopt the general formation process and the general capacity process in the battery production field. Since after the formation process, processes such as secondary electrolyte injection and high-temperature aging need to be carried out, and then the capacity process is carried out, the force of the detection fixture needs to be removed in the middle. Here, the swelling force value at the end of the formation of each battery cell needs to be recorded, for example, recorded as F3. Then, when the capacity process is carried out, the initial fixture force applied to the battery cell should be F3.

[0106] The embodiment of the present application can not only accurately and timely detect abnormal battery cells and reduce the output of defective products by monitoring the swelling force value of each battery cell in real time in the battery production line, but also improve the quality and safety of battery cell production.

[0107] In one or more embodiments of the present application, in some embodiments, the obtaining of the first swelling force value of each battery cell based on the first formation process in the production process includes:

[0108] Let each battery cell stand for a first preset duration, and perform constant current charging on each battery cell at a first charging rate for a second preset duration.

[0109] Let each of the battery cells stand still for the first preset duration, and perform constant current charging on each of the battery cells for a third preset duration based on the first charging rate, so that each of the battery cells reaches a second state of charge from a first state of charge, and let each of the battery cells stand still for the first preset duration;

[0110] Perform constant current charging on each of the battery cells for a fourth preset duration based on a second charging rate; let each of the battery cells stand still for the first preset duration;

[0111] Perform constant current charging on the battery cells for the fourth preset duration based on the second charging rate, so that each of the battery cells reaches a third state of charge from the second state of charge, and let each of the battery cells stand still for the first preset duration;

[0112] Obtain a first swelling force value corresponding to each of the battery cells between the first state of charge and the third state of charge.

[0113] Specifically, in the embodiment of the present application, the value range of the pressure value corresponding to the above formation process is [-15, -30] kPa, the value range of the first preset duration can be [25, 35] seconds, the value range of the second preset duration can be [5, 10] minutes, the first charging rate can be 0.1C, the value range of the third preset duration can be [20, 25] minutes, and the value range of the fourth preset duration can be [25, 35] minutes. The first charging rate can be 0.1C, the second charging rate can be 0.3C, the first state of charge is a full discharge state, the second state of charge is 5% SOC, and the third state of charge is 35% SOC.

[0114] In one example, the above formation process flow includes the following steps:

[0115] 1) Rest 30s (stand still for 30 seconds);

[0116] 2) 0.1C CC 7min (0.1 charging rate, constant current charging for 7 minutes);

[0117] 3) Rest 30s (stand still for 30 seconds);

[0118] 4) 0.1C CC 23min (0.1 charging rate, constant current charging for 23 minutes);

[0119] 5) Rest 30s (stand still for 30 seconds);

[0120] 6) 0.3C CC 30min (0.3 charging rate, constant current charging for 30 minutes);

[0121] 7) Rest 30s (stand still for 30 seconds);

[0122] 8) 0.3C CC 30min (Constant current charge at 0.3C rate for 30 minutes);

[0123] 9) Rest 30s (Rest for 30 seconds).

[0124] Among them, the above step 1) is used to monitor whether the open circuit voltage (OCV) of the wetted battery cell is normal; the processes of the above steps 2)-5) are used to enable the battery cell to form a stable and dense SEI layer through low-rate charging. After the battery cell reaches 5% SOC, adding a 30s rest duration in the middle can help the gas inside the battery cell to be discharged. During the rest period, the chemical reactions inside the battery cell tend to reach equilibrium, and the gas in the electrolyte can be discharged through the breathable structure of the battery cell.

[0125] In the processes of the above steps 6)-9), the battery cell is usually charged to 30% of its capacity and finally reaches 35% SOC through high-rate formation. This process ensures that the battery cell completes formation at a low state of charge, avoiding damage to the battery cell caused by excessive voltage and current. Adding a 30s rest duration can help the gas inside the battery cell to be discharged.

[0126] By staging the rest and charging in the embodiments of the present application, the change in the swelling force of the battery cell at different states of charge can be accurately captured. Obtaining the swelling force data in the formation process helps to early identify potential abnormalities of the battery cell. Based on the actual measurement data, it can also provide support for the production quality control and process optimization of the battery cell.

[0127] In one or more embodiments of the present application, obtaining the second swelling force value of each battery cell based on the capacity process during production includes:

[0128] Rest each battery cell for a first preset duration, and perform constant current charging on each battery cell based on a third charging rate until each battery cell reaches the maximum charging voltage;

[0129] Perform constant voltage charging on each battery cell at the maximum charging voltage until the charging current drops to a fourth charging rate to make each battery cell reach a fully charged state;

[0130] Obtain the corresponding second swelling force value of each battery cell in the capacity process.

[0131] Specifically, in the embodiments of the present application, the above third charging rate can be 0.5C, the fourth charging rate is 0.05C, the maximum charging voltage of a lithium iron phosphate battery (LFP) is 3.65V or 3.8V, and for a ternary lithium battery (NCM), the maximum charging voltage of NCM is 4.3V.

[0132] In one example, the above capacity process flow includes the following steps:

[0133] 1) Rest for 30 s;

[0134] 2) 0.5C CC Vmax (0.5 charge rate, constant current charging to the maximum charging voltage)

[0135] 3) Vmax CV 0.05C (0.05 charge rate, constant voltage charging to reduce the charging current to 0.05C until the battery cell reaches the fully charged state). Here, the constant voltage charging can depolarize the battery cell.

[0136] By performing staged rest and charging, the embodiments of the present application can accurately capture the change in the swelling force of the battery cell at different state of charge (SOC) levels. Obtaining the swelling force data during the capacity process helps to early identify potential battery cell abnormalities. Based on the actual measurement data, it can also provide support for the production quality control and process optimization of the battery cell.

[0137] In one or more embodiments of the present application, in some embodiments, obtaining the first swelling force value and the second swelling force value of each battery cell further includes:

[0138] Obtaining the first swelling force value and the second swelling force value of each battery cell based on the second formation process; the second formation process is used to bring each battery cell from the first SOC level to the fourth SOC level. The second formation process includes the steps corresponding to the first formation process, the steps corresponding to the capacity process, and the operation step of discharging each battery cell to the fifth SOC level for aging.

[0139] Specifically, in the embodiments of the present application, the fourth SOC level can range from 99% SOC to 100% SOC, and the fifth SOC level can be 90% SOC. The operation step of discharging each battery cell to the fifth SOC level for aging includes: discharging the battery to a preset SOC for aging. For example, it can be discharged at a rate of 0.5 - 1.0C for 0.1CnAh to discharge the battery cell to 90% SOC for aging.

[0140] By obtaining the first swelling force value and the second swelling force value of the battery cell through the second formation process and combining the aging operation, the embodiments of the present application can comprehensively evaluate the swelling force characteristics of the battery cell at different SOC levels and usage conditions. This method not only improves the detection accuracy of abnormal battery cells but also provides an important basis for the production quality control and process optimization of the battery cell.

[0141] The embodiments of the present invention also provide a battery detection device, which is used to execute the battery detection method provided in the above embodiments, as Figure 7 shown. This device includes:

[0142] An acquisition unit 702, configured to acquire, for each of a plurality of battery cells, an expansion force value corresponding to each battery cell at different states of charge.

[0143] A determination unit 704, configured to determine whether there is an abnormal battery cell among the plurality of battery cells based on the expansion force values corresponding to each battery cell.

[0144] In the technical solution of the embodiment of the present invention, for each of a plurality of battery cells during mass production, by acquiring the expansion force values of each battery cell at different states of charge; and based on the expansion force values corresponding to each battery cell, determining whether there is an abnormal battery cell among the plurality of battery cells. Compared with the method in the related art that usually uses a prediction model to identify abnormal battery cells, the present application can not only accurately and effectively identify the battery cells with abnormal expansion force in mass-produced battery cells, reduce the dependence of the detection process on the type and structure of the battery cells, but also has small limitations and high universality.

[0145] In one or more embodiments of the present application, the acquisition unit 702 includes:

[0146] A first acquisition module, configured to acquire a first expansion force value and a second expansion force value of each battery cell; the first expansion force value is the peak expansion force when the battery cell is within a first state-of-charge range, and the second expansion force value is the peak expansion force when the battery cell is within a second state-of-charge range, and the maximum state of charge within the first state-of-charge range is less than the minimum state of charge within the second state-of-charge range.

[0147] In one or more embodiments of the present application, the determination unit 704 includes:

[0148] A determination module, configured to determine whether there is an abnormal battery cell among the plurality of battery cells based on the first expansion force value corresponding to each battery cell and / or the second expansion force value corresponding to each battery cell.

[0149] In one or more embodiments of the present application, the determination module includes:

[0150] A determination subunit, configured to determine that there is an abnormal battery cell among the plurality of battery cells according to the occurrence of an expansion force outlier value in a first expansion force set composed of the first expansion force values corresponding to each battery cell, or according to the occurrence of an expansion force outlier value in a second expansion force set composed of the second expansion force values corresponding to each battery cell.

[0151] In one or more embodiments of the present application, the determination subunit includes:

[0152] A first acquisition sub-module, configured to acquire the difference between the first expansion force value and the second expansion force value corresponding to each battery cell.

[0153] The first determination sub-module is configured to determine that there is an abnormal battery cell among the multiple battery cells when there is an expansion force outlier in the set of differences composed of the differences.

[0154] In one or more embodiments of the present application, the determination subunit includes:

[0155] The second acquisition sub-module is configured to acquire a first weight coefficient corresponding to the first expansion force value of each battery cell, and a second weight coefficient corresponding to the second expansion force value of each battery cell;

[0156] The second determination sub-module is configured to determine a first product of the first expansion force value and the first weight coefficient of each battery cell, and a second product of the second expansion force value and the second weight coefficient of each battery cell;

[0157] The calculation sub-module is configured to calculate the difference between the first product and the second product corresponding to each battery cell;

[0158] The third determination sub-module is configured to determine that there is an abnormal battery cell among the multiple battery cells when there is an expansion force outlier in the set of differences composed of the differences.

[0159] In one or more embodiments of the present application, the acquisition unit 702 includes:

[0160] The second acquisition module is configured to acquire the first expansion force value of each battery cell based on the first formation process in the production process; the first formation process is used to make the battery cell in the first state of charge range;

[0161] The third acquisition module is configured to acquire the second expansion force value of each battery cell based on the capacity process in the production process; the capacity process is used to make the battery cell in the second state of charge range.

[0162] In one or more embodiments of the present application, the second acquisition module includes:

[0163] The first static charging sub-unit is configured to statically charge each battery cell for a first preset duration, and perform constant current charging on each battery cell for a second preset duration based on a first charging rate;

[0164] The second static charging sub-unit is configured to statically charge each battery cell for the first preset duration, perform constant current charging on each battery cell for a third preset duration based on the first charging rate, so that each battery cell reaches a second state of charge from the first state of charge, and statically charge each battery cell for the first preset duration;

[0165] The third static charging sub-unit is configured to perform constant current charging on each of the battery cells at the second charging rate for a fourth preset duration; and statically charge each of the battery cells for the first preset duration.

[0166] The fourth static charging sub-unit is configured to perform constant current charging on the battery cells at the second charging rate for the fourth preset duration, so that each of the battery cells reaches the third state of charge from the second state of charge, and statically charge each of the battery cells for the first preset duration.

[0167] The first acquisition sub-unit is configured to acquire a first swelling force value corresponding to each of the battery cells between the first state of charge and the third state of charge.

[0168] In one or more embodiments of the present application, the third acquisition module includes:

[0169] The fifth static charging sub-unit is configured to statically charge each of the battery cells for the first preset duration, and perform constant current charging on each of the battery cells based on a third charging rate until each of the battery cells reaches the maximum charging voltage.

[0170] The static discharge sub-unit is configured to perform constant voltage charging on each of the battery cells at the maximum charging voltage until the charging current drops to the fourth charging rate, so that each of the battery cells reaches the fully charged state.

[0171] The second acquisition sub-unit is configured to acquire the second swelling force value corresponding to each of the battery cells in the capacity process.

[0172] In one or more embodiments of the present application, the acquisition unit 702 further includes:

[0173] The fourth acquisition module is configured to acquire the first swelling force value and the second swelling force value of each of the battery cells based on a second formation process; the second formation process is used to make each of the battery cells reach the fourth state of charge from the first state of charge, and the second formation process includes the steps corresponding to the first formation process, the steps corresponding to the capacity process, and the operation steps of discharging each of the battery cells to the fifth state of charge for aging.

[0174] Figure 8 It is a logical structure block diagram of an electronic device shown according to an exemplary embodiment. For example, the electronic device 800 may be an electronic device such as a BMS, a vehicle-mounted controller, a motor controller, or a domain controller disposed inside an electrical device.

[0175] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory including instructions. The above instructions can be executed by a battery processor to complete the above battery detection method, and the method includes: for each of a plurality of battery cells, obtaining the swelling force value of each battery cell at different state of charge; based on the swelling force value corresponding to each battery cell, determining whether there is an abnormal battery cell among the plurality of battery cells. Optionally, the above instructions can also be executed by a processor of the battery to complete other steps involved in the above exemplary embodiment. For example, the non-transitory computer-readable storage medium can be ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device, etc.

[0176] In an exemplary embodiment, an application program / computer program product is also provided, including one or more instructions. The one or more instructions can be executed by a processor of the battery to complete the above battery detection method, and the method includes: for each of a plurality of battery cells, obtaining the swelling force value of each battery cell at different state of charge; based on the swelling force value corresponding to each battery cell, determining whether there is an abnormal battery cell among the plurality of battery cells. Optionally, the above instructions can also be executed by a processor of the battery to complete other steps involved in the above exemplary embodiment. Figure 8 FIG. is an example diagram of an electronic device 800. Those skilled in the art can understand that the schematic Figure 8 is merely an example of the electronic device 800, and does not constitute a limitation on the electronic device 800. It may include more or fewer components than shown in the figure, or combine certain components, or different components. For example, the electronic device 800 may also include input / output devices, network access devices, buses, etc.

[0177] The so-called processor 802 may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor, or the processor 802 may also be any conventional processor, etc. The processor 802 is the control center of the electronic device 800, and connects various parts of the entire electronic device 800 through various interfaces and lines.

[0178] The memory 801 can be used to store computer-readable instructions. By running or executing the computer-readable instructions or modules stored in the memory 801, and by invoking the data stored in the memory 801, the processor 802 realizes various functions of the electronic device 800. The memory 801 mainly includes a program storage area and a data storage area. Among them, the program storage area can store an operating system, application programs required for at least one function (such as a sound playback function, an image playback function, etc.); the data storage area can store data created according to the use of the electronic device 800. In addition, the memory 801 can include a hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one magnetic disk storage device, flash memory device, read-only memory (ROM), random access memory (RAM), or other non-volatile / volatile storage devices.

[0179] If the modules integrated in the electronic device 800 are implemented in the form of software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, to implement all or part of the processes in the above-described embodiment methods of the present invention, computer-readable instructions can also be used to instruct relevant hardware to complete. The computer-readable instructions can be stored in a computer-readable storage medium. When the computer-readable instructions are executed by the processor, the steps of the above-described various method embodiments can be implemented.

[0180] After considering the specification and practicing the invention disclosed herein, those skilled in the art will readily conceive of other embodiments of the present application. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include well-known knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present application are pointed out by the following claims.

[0181] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present application is only limited by the appended claims.

[0182] The user information involved in this application (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) are all information and data that have been authorized by the user or fully authorized by all parties. Moreover, the collection, use, and processing of relevant data need to comply with the relevant laws, regulations, and standards of relevant countries and regions, and corresponding operation entrances are provided for users to choose to authorize or reject.

Claims

1. A battery detection method, characterized in that: include: For each of the multiple battery cells, a first expansion force value and a second expansion force value of each battery cell during the production process are obtained; the first expansion force value is a peak value of the expansion force of the battery cell when it is within a first state of charge range, the second expansion force value is a peak value of the expansion force of the battery cell when it is within a second state of charge range, and the maximum state of charge within the first state of charge range is less than the minimum state of charge within the second state of charge range; determining whether there is an abnormal battery cell among the plurality of battery cells based on the first expansion force value and the second expansion force value corresponding to each battery cell; The obtaining of the first expansion force value and the second expansion force value of each battery cell during the production process comprises: obtaining the first expansion force value of each battery cell based on a first formation process during the production process; the first formation process is used to place the battery cell in the first state of charge range; The second expansion force value of each battery cell is obtained based on a capacity process in the production process; the capacity process is used to put the battery cell in the second state of charge range.

2. The method according to claim 1, characterized in that The determining whether there is an abnormal battery cell among the plurality of battery cells based on the first expansion force value and the second expansion force value corresponding to each battery cell includes: Obtaining a difference between the first expansion force value and the second expansion force value corresponding to each battery cell; When an expansion force outlier appears in the difference value set composed of the difference values, it is determined that an abnormal battery cell exists in the plurality of battery cells.

3. The method according to claim 1, characterized in that The determining whether there is an abnormal battery cell among the plurality of battery cells based on the first expansion force value and the second expansion force value corresponding to each battery cell includes: Obtaining a first weight coefficient corresponding to the first expansion force value corresponding to each battery cell, and a second weight coefficient corresponding to the second expansion force value corresponding to each battery cell; Determine a first product of a first expansion force value and a first weight coefficient of each battery cell, and a second product of a second expansion force value and a second weight coefficient of each battery cell; Calculating the difference between the first product and the second product corresponding to each battery cell; When an expansion force outlier appears in the difference value set composed of the difference values, it is determined that an abnormal battery cell exists in the plurality of battery cells.

4. The method according to claim 1, characterized in that: The obtaining of the first expansion force value of each battery cell based on the first formation process in the production process includes: Allow each of the battery cells to stand for a first preset time, and perform constant current charging on each of the battery cells for a second preset time based on the first charging rate; Allow each of the battery cells to stand for the first preset time, perform constant current charging on each of the battery cells based on the first charging rate for a third preset time, so that each of the battery cells reaches a second state of charge from a first state of charge, and allow each of the battery cells to stand for the first preset time; Performing constant current charging on each of the battery cells for a fourth preset time based on the second charging rate; and leaving each of the battery cells at rest for the first preset time; Based on the second charging rate, the battery cells are charged with a constant current for a fourth preset time period, so that each of the battery cells reaches a third state of charge from the second state of charge, and each of the battery cells is left to rest for the first preset time period; A first expansion force value corresponding to each of the battery cells from the first state of charge to the third state of charge is obtained.

5. The method according to claim 1, characterized in that The obtaining the second expansion force value of each battery cell based on the capacity process in the production process includes: Leaving each of the battery cells stationary for a first preset time, and performing constant current charging on each of the battery cells based on a third charging rate until each of the battery cells reaches a maximum charging voltage; Performing constant voltage charging on each of the battery cells at the maximum charging voltage until the charging current drops to a fourth charging rate, so that each of the battery cells reaches a fully charged state; The second expansion force value corresponding to each battery cell in the capacity process is obtained.

6. The method according to claim 1, characterized in that The obtaining of the first expansion force value and the second expansion force value of each battery cell further includes: The first expansion force value and the second expansion force value of each battery cell are obtained based on a second formation process; the second formation process is used to make each battery cell reach a fourth state of charge from a first state of charge, and the second formation process includes steps corresponding to the first formation process, steps corresponding to the capacity process, and an operation step of discharging each battery cell to a fifth state of charge for aging.

7. A battery detection device, characterized in that: include: an acquisition unit, configured to acquire, for each of the plurality of battery cells, a first expansion force value and a second expansion force value of each of the battery cells during a production process; the first expansion force value is a peak value of the expansion force of the battery cell when the battery cell is within a first state of charge range, the second expansion force value is a peak value of the expansion force of the battery cell when the battery cell is within a second state of charge range, and a maximum state of charge within the first state of charge range is less than a minimum state of charge within the second state of charge range; Wherein, the obtaining of the first expansion force value and the second expansion force value of each battery cell during the production process includes: obtaining the first expansion force value of each battery cell based on a first formation process in the production process; the first formation process is used to make the battery cell in the first state of charge range; obtaining the second expansion force value of each battery cell based on a capacity process in the production process; the capacity process is used to make the battery cell in the second state of charge range; A determination unit is configured to determine whether there is an abnormal battery cell among the plurality of battery cells based on the first expansion force value and the second expansion force value corresponding to each battery cell.

8. An electronic device, comprising a memory and a processor, characterized in that: A computer program is stored in the memory, and the processor is configured to execute the method according to any one of claims 1 to 6 through the computer program.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein the program executes the method described in any one of claims 1 to 6 when executed.

10. A computer program product, comprising a computer program, characterized in that The computer program is executed by a processor to implement the method according to any one of claims 1 to 6.

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