Battery detection method and device, electronic equipment, storage medium and computer program product

Abstract

The invention discloses a battery detection method and device, electronic equipment, a storage medium and a computer program product. The method comprises the following steps: for each battery cell in a plurality of battery cells, acquiring a first expansive force value and a second expansive force value of each battery cell in a production process; the first expansive force value is an expansive force peak value when the battery cell is in a first charge state range, the second expansive force value is an expansive force peak value when the battery cell is in a second charge state range, and the maximum charge state in the first charge state range is smaller than the minimum charge state in the second charge state range; and based on the first expansive force value and the second expansive force value corresponding to each battery cell, determining whether an abnormal battery cell exists in the plurality of battery cells. According to the embodiment of the invention, the battery cell with abnormal battery cell expansibility in mass-produced battery cells can be effectively and accurately identified, and the safety of battery production is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, 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 green environmental protection. They 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, a destruction / repair process of the solid electrolyte interface (SEI) will occur inside the battery, the SEI layer will thicken, and the positive and negative pole pieces will rebound, all of which will increase the expansion force of the lithium battery cell; when this expansion force increases to a certain range, it will affect the structure of the battery module, such as battery performance degradation, battery casing rupture, electrolyte leakage, internal battery short circuit and other safety hazards. Due to possible abnormal incoming materials, abnormal environmental water content, abnormal production process parameters, etc. in the production process, the expansion force of the battery cells of the battery products may exceed the safe range. In the related technology, a prediction model is usually used to identify a small number of abnormal battery cells with battery cell expansion force exceeding the safe range in the research and development stage; however, the above method cannot effectively and accurately identify battery cells with abnormal battery cell expansion force in mass-produced battery cells.

[0004] The above statements are only used to provide background information related to the present application and do not necessarily constitute prior art. Summary of the invention

[0005] In view of the above problems, the present application provides a battery detection method, device, electronic device, storage medium and computer program product, which can solve the technical problem in the related art that it is impossible to effectively and accurately identify battery cells with abnormal battery expansion force in mass-produced battery cells.

[0006] In a first aspect, the present application provides a battery detection method, comprising: for each battery cell in a plurality of battery cells, obtaining a first expansion force value and a second expansion force value of each battery cell during a production process; the first expansion force value is a peak expansion force value of the battery cell when the battery cell is within a first state of charge range, the second expansion force value is a peak expansion force value of the battery cell when the battery cell is within a second state of charge range, 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 expansion force value of each battery cell at different states of charge; Based on the first expansion force value and the second expansion force value corresponding to each battery cell, it is determined whether there is an abnormal battery cell among the plurality of battery cells.

[0007] In the technical solution of the embodiment of the present invention, for each of the multiple battery cells in the mass production process, the expansion force value of each battery cell at different charge states is obtained; based on the expansion force value corresponding to each battery cell, it is determined whether there is an abnormal battery cell in the multiple battery cells. Compared with the method of using a prediction model to identify abnormal batteries in the related art, the present application can not only accurately and effectively identify the battery cells with abnormal battery cell expansion force in mass production batteries, but also reduce the dependence of the detection process on the battery cell type and structure, and has few limitations and high universality.

[0008] In some embodiments, 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; and determining that there is an abnormal battery cell among the multiple battery cells when an expansion force outlier appears in a difference set composed of the differences.

[0009] The embodiment of the present application obtains the difference between the first expansion force value and the second expansion force value corresponding to the battery cell, and an expansion force outlier appears in a difference set composed of the difference. This can not only promptly discover and eliminate abnormal battery cells, but also reduce the detection error of the first expansion force value and the second expansion force value in the acquisition process, thereby significantly improving the accuracy of identifying battery cells with abnormal battery cell expansion force in mass-produced battery cells.

[0010] In some embodiments, 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 set composed of the differences, it is determined that an abnormal battery cell exists in the plurality of battery cells.

[0011] The embodiment of the present application analyzes the expansion force outliers appearing in multiple battery cells by weighted difference, which can not only more accurately identify abnormal battery cells and avoid misjudgment caused by fluctuations in a single expansion force value. Not only can the abnormal battery cells be identified more accurately, but also the weight coefficients of the first expansion force value and the second expansion force value can be adjusted according to actual needs, thereby improving the flexibility and universality of detection.

[0012] In some embodiments, obtaining the first expansion force value and the second expansion force value of each battery cell includes: Obtaining a first expansion force value of each battery cell based on a first formation process in a 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.

[0013] The embodiment of the present application can monitor the expansion force value of each battery cell in real time in the battery production line, which can not only accurately and timely detect abnormal batteries and reduce the output of defective products, but also improve the quality and safety of battery cell production.

[0014] In some embodiments, obtaining 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.

[0015] The embodiment of the present application can accurately capture the changes in the expansion force of the battery cell under different charge states by standing and charging in stages. Acquiring expansion force data during the formation process helps to identify potential battery cell abnormalities at an early stage, and based on actual measurement data, can also provide support for production quality control and process optimization of the battery cell.

[0016] In some embodiments, 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.

[0017] The embodiment of the present application can accurately capture the changes in the expansion force of the battery cell at different charge states by standing and charging in stages. Acquiring expansion force data in the capacity process helps to identify potential battery cell abnormalities at an early stage, and based on actual measurement data, can also provide support for production quality control and process optimization of the battery cell.

[0018] In some embodiments, obtaining 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.

[0019] The embodiment of the present application obtains the first expansion force value and the second expansion force value of the battery cell through the second formation process, and combined with the aging operation, can comprehensively evaluate the expansion force characteristics of the battery cell under different charge states and usage conditions. This method not only improves the detection accuracy of abnormal battery cells, but also provides an important basis for production quality control and process optimization of battery cells.

[0020] In a second aspect, an embodiment of the present invention provides a battery detection device, comprising: an acquisition unit, for acquiring, for each battery cell in a plurality of battery cells, a first expansion force value and a second expansion force value of each battery cell in a production process; the first expansion force value is a peak expansion force value of the battery cell when it is in a first state of charge range, the second expansion force value is a peak expansion force value of the battery cell when it is in a second state of charge range, 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, for 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.

[0021] In a third aspect, an embodiment of the present application further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the battery detection method as described in the first aspect is implemented.

[0022] In a fourth aspect, an embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the battery detection method as described in the first aspect is implemented.

[0023] In a fifth aspect, an embodiment of the present application further provides a computer program product, including a computer program, wherein the computer program is executed by a processor to implement the battery detection method as described in the first aspect.

[0024] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings: Figure 1 A flowchart of a battery detection method provided in an embodiment of the present application; Figure 2 A flowchart of another battery detection method provided in an embodiment of the present application; Figure 3 A schematic diagram of a battery cell expansion force curve provided in an embodiment of the present application; Figure 4 A flowchart of another battery detection method provided in an embodiment of the present application; Figure 5 is a flow chart of another battery detection method provided in an embodiment of the present application; Figure 6 It is a schematic diagram of expansion force difference distribution of a battery detection method provided in an embodiment of the present application; Figure 7 is a structural schematic diagram of a battery detection device provided in an embodiment of the present application; Figure 8 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians 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" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0028] In the description of the embodiments of the present invention, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0029] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] In the description of the embodiments of the present invention, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0031] In the description of the embodiments of the present invention, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0032] At present, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. In the fields of electric transportation supply, military equipment, aerospace and so on, batteries are usually used to provide power.

[0033] Among various types of power batteries, lithium batteries are widely used in new energy vehicles, consumer electronics, energy storage systems and other fields due to their advantages such as high power density, high energy density, long cycle life, high output voltage, and green environmental protection. How to improve the charging speed of lithium batteries while ensuring charging performance has become a hot topic of current research.

[0034] As the degree of cycle aging (or storage aging) of lithium batteries increases, the solid electrolyte interface (SEI) will undergo a destruction / repair process, the SEI layer will thicken, and the positive and negative pole pieces will rebound, all of which will increase the expansion force of the lithium battery cell; when this expansion force increases to a certain range, it will affect the structure of the battery module, such as battery performance degradation, battery shell rupture, electrolyte leakage, internal battery short circuit and other safety hazards. Due to possible abnormalities in incoming materials, abnormal environmental water content, abnormal production process parameters, etc. during the production process, the expansion force of the battery cell of the battery product will exceed the safe range.

[0035] In related technologies, prediction models are usually used to identify a small number of abnormal cells in the R&D stage whose expansion force exceeds the safe range. The above method is limited to the R&D stage of the battery, testing the R&D cells (generally only testing a single-digit number of cells) and establishing a certain prediction model; this method cannot take into account the abnormal conditions that may occur in mass-produced cells.

[0036] Based on the above problems existing in the related art, some embodiments of the present application propose a battery detection method, device, electronic device and storage medium. The method includes: for each battery cell in a plurality of battery cells, obtaining the expansion force value of each battery cell at different charge states; based on the expansion force value corresponding to each battery cell, determining whether there is an abnormal battery cell in the plurality of battery cells.

[0037] In the technical solution of the embodiment of the present invention, for each of the multiple battery cells in the mass production process, the expansion force value of each battery cell at different charge states is obtained; based on the expansion force value corresponding to each battery cell, it is determined whether there is an abnormal battery cell in the multiple battery cells. Compared with the method of using a prediction model to identify abnormal batteries in the related art, the present application can not only accurately and effectively identify the battery cells with abnormal battery cell expansion force in mass production batteries, but also reduce the dependence of the detection process on the battery cell type and structure, and has few limitations and high universality.

[0038] The specific process of the battery detection method of the present application is described in detail below through specific embodiments. Figure 1 The flowchart of the battery detection method shown in FIG. 1 includes the following steps: S102, for each of the plurality of battery cells, obtaining an expansion force value of each battery cell at different states of charge; S104: Determine whether there is an abnormal battery cell among the plurality of battery cells based on the expansion force value corresponding to each battery cell.

[0039] Specifically, in an embodiment of the present invention, the above-mentioned battery cell type may be, for example, a ternary lithium battery cell or a lithium iron phosphate battery cell. In order to obtain the expansion force change curve of each battery cell during the battery production process, it is necessary to use a clamp to monitor the expansion force of the battery cell during the production process. For example, in the formation process, when the battery cell is formed with a clamp, the initial clamp force of each battery cell (the clamp force applied to each battery cell before formation) is in the range of 500N~2000N, with the best being 1000N. Based on the above-mentioned clamp, the corresponding expansion force value of each battery cell under different states of charge (SOC) during the production process can be obtained.

[0040] In one example, by obtaining the expansion force value of each battery cell under different charge states, and then using the standard deviation or local outlier detection algorithm to analyze whether there are abnormal points in the battery cell expansion force data, if the number of abnormal points is greater than a preset value, it can be determined whether there are abnormal batteries among the multiple battery cells.

[0041] By obtaining the expansion force values ​​of each battery cell at different charge states, the normal range of the expansion force of the battery cell can be predicted. When the expansion force of a battery cell exceeds the normal range, it can be judged as abnormal. It can be determined whether there is an abnormal battery cell among the multiple battery cells.

[0042] In addition, the changes in the expansion force growth rates of the above-mentioned multiple battery cells can also be monitored to determine abnormal battery cells; for example, when the expansion force growth rate of a battery cell exceeds the normal range and lasts for a long time, the battery cell can be determined to be an abnormal battery cell.

[0043] In the technical solution of the embodiment of the present invention, for each of the multiple battery cells in the mass production process, the expansion force value of each battery cell at different charge states is obtained; based on the expansion force value corresponding to each battery cell, it is determined whether there is an abnormal battery cell in the multiple battery cells. Compared with the method of using a prediction model to identify abnormal batteries in the related art, the present application can not only accurately and effectively identify the battery cells with abnormal battery cell expansion force in mass production batteries, but also reduce the dependence of the detection process on the battery cell type and structure, and has few limitations and high universality.

[0044] In one or more embodiments of the present application, Figure 2 As shown, the above battery detection method includes the following steps: S202, for each of the multiple battery cells, obtaining a first expansion force value and a second expansion force value of each battery cell; the first expansion force value is a peak expansion force value of the battery cell when it is within a first state of charge range, the second expansion force value is a peak expansion force value 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; S104: Determine whether there is an abnormal battery cell among the plurality of battery cells based on the expansion force value corresponding to each battery cell.

[0045] Specifically, in the embodiments of the present application, Figure 3 As shown, each battery cell will correspond to different expansion force values ​​at different charge states during the charging process. According to the corresponding relationship between the charge state and the expansion force value, the expansion force curve of each battery cell can be obtained.

[0046] During the charging stage of lithium-ion batteries, the expansion force of the battery cell increases due to factors such as the formation of the SEI layer and the expansion of particles caused by the insertion of lithium into graphite. Figure 3 As shown, there is a maximum expansion force point near 30% SOC, namely the first expansion force value F1, and there is a maximum expansion force point near 95% SOC, namely the second expansion force value F2.

[0047] When the cell is charged for the first time, the value of F2 is much greater than the value of F1, but as the cell cycles or storage aging increases, both F1 and F2 will increase slowly, with the increase of F1 being greater than F2; when the lithium-ion battery ages, the rate of increase of the cell's expansion force will increase after reaching the expansion force inflection point, that is, the risk of the cell's expansion force failing during the warranty life. If the difference between F1 and F2 is larger, the longer the expansion force of the cell reaches the expansion force inflection point, the later the battery health (State of Health, SOH) will lag, that is, the risk of the cell's expansion force failing during the warranty life. Conversely, if the difference between F1 and F2 is smaller, the earlier the expansion force of the cell reaches the expansion force inflection point, that is, the risk of the cell's expansion force failing during the warranty life is higher.

[0048] In the embodiment of the present application, by obtaining the expansion force peak value of the battery cell under different charge states and according to its change law, the failure characteristic value of the battery cell expansion force is determined. Not only can the battery cell with abnormal battery cell expansion force in mass-produced battery cells be accurately and effectively identified, but also it has high universality and early warning capabilities, ensuring the safety and reliability of the battery cell during use.

[0049] In one or more embodiments of the present application, Figure 4 As shown, the above battery detection method includes the following steps: S402, for each of the multiple 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 value of the battery cell when it is in a first state of charge range, the second expansion force value is the peak expansion force value of the battery cell when it is in 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.

[0050] S404: 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.

[0051] Specifically, in the embodiment of the present application, multiple battery cells in the production process are charged and discharged for multiple cycles, and then the first expansion force value and the second expansion force value of each battery cell in each cycle are obtained. Based on 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 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 can be accurately determined whether there are abnormal batteries in the multiple battery cells.

[0052] This application determines the failure characteristic value of the expansion force of the battery cell by obtaining at least one expansion force peak value of the battery cell under different charge states. 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 capabilities. Ensure the safety and reliability of the battery cells during use.

[0053] In one or more embodiments of the present application, determining whether there is an abnormal cell among the plurality of cells based on the first expansion force value corresponding to each cell or the second expansion force value corresponding to each cell includes: An abnormal cell is determined to exist among the multiple battery cells based on the presence of an expansion force outlier in a first expansion force set consisting of the first expansion force values ​​corresponding to each battery cell, or based on the presence of an expansion force outlier in a second expansion force set consisting of the second expansion force values ​​corresponding to each battery cell.

[0054] Specifically, in the embodiment of the present application, outlier detection is performed on the first expansion force set or the second expansion force set, for example, using a statistical analysis method (such as a box plot, standard deviation) or a machine learning method (such as a local outlier factor algorithm) to detect outliers in the set. If the expansion force value of a certain battery cell obviously deviates from the normal distribution range of the set, the battery cell is determined to be an abnormal battery cell.

[0055] The embodiment of the present application can accurately identify abnormal cells by analyzing the outliers in the expansion force peak value set. During mass production, by real-time monitoring of the expansion force outliers in the cells, abnormal cells can be discovered and removed in a timely manner, thereby improving the quality of battery production. It can also be applied to various types of cells without being limited by the cell material or structure.

[0056] In one or more embodiments of the present application, Figure 5 As shown, the above battery detection method includes the following steps: S402, for each of the multiple 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 value of the battery cell when it is in a first state of charge range, the second expansion force value is the peak expansion force value of the battery cell when it is in 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.

[0057] S504, obtaining a difference between the first expansion force value and the second expansion force value corresponding to each battery cell; S506: When an expansion force outlier appears in the difference set composed of the differences, determine that an abnormal battery cell exists in the plurality of battery cells.

[0058] Specifically, in the embodiment of the present application, since in the process of obtaining the first expansion force value and the second expansion force value, there will be deviations when the detection fixture detects the expansion force value of the battery cell, which is inconsistent with the actual expansion force, the present application obtains the difference between the first expansion force value and the second expansion force value corresponding to each battery cell, and calculates the expansion force outlier value in the difference set composed of the difference, so as to determine whether there is an abnormal battery cell among the multiple battery cells. In one example, for example, if the first expansion force value detected is 800N (the actual value is 1000N) and the second expansion force value is 1500N (the actual value is 1700N), then the difference between the first expansion force value 800N and the second expansion force value 1500N detected is the same as the difference corresponding to the actual values ​​of the two. In this way, the accuracy of abnormal cell detection can be significantly improved.

[0059] In a test example, the first expansion force value F1 and the second expansion force value F2 of all the cells produced on that day, as well as the difference between F1 and F2, are obtained; Figure 6 As shown, in the statistical data of F1 and F2 of the 200 monitored battery cells (1kgf = 1*9.8N), the battery cells with significantly lower difference (less than 78kgf) are abnormal battery cells, which have a higher risk of expansion force failure and should be treated as defective products during production.

[0060] The above step S402 has been explained in the previous text and will not be repeated here.

[0061] The embodiment of the present application obtains the difference between the first expansion force value and the second expansion force value corresponding to the battery cell, and an expansion force outlier appears in a difference set composed of the difference. This can not only promptly discover and eliminate abnormal battery cells, but also reduce the detection error of the first expansion force value and the second expansion force value in the acquisition process, thereby significantly improving the accuracy of identifying battery cells with abnormal battery cell expansion force in mass-produced battery cells.

[0062] In one or more embodiments of the present application, in some embodiments, determining 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 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.

[0063] The embodiment of the present application analyzes the expansion force outliers appearing in multiple battery cells by weighted difference, which can not only more accurately identify abnormal battery cells and avoid misjudgment caused by fluctuations in a single expansion force value. Not only can the abnormal battery cells be identified more accurately, but also the weight coefficients of the first expansion force value and the second expansion force value can be adjusted according to actual needs, thereby improving the flexibility and universality of detection.

[0064] In one or more embodiments of the present application, the obtaining of the first expansion force value and the second expansion force value of each battery cell includes: Obtaining a first expansion force value of each battery cell based on a first formation process in a 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.

[0065] It should be noted that the formation process of the formation process in the embodiment of the present application can adopt the formation process commonly used in the field of battery production and the common capacity process. Since the formation process needs to be followed by the second electrolyte injection, high temperature aging and other processes, and then the capacity process, the detection clamp force needs to be removed in the middle. Here, the expansion force value of each battery cell at the end of formation needs to be recorded, for example, recorded as F3. When the capacity process is performed, the initial clamp force applied to the battery cell should be F3.

[0066] The embodiment of the present application can monitor the expansion force value of each battery cell in real time in the battery production line, which can not only accurately and timely detect abnormal batteries and reduce the output of defective products, but also improve the quality and safety of battery cell production.

[0067] In one or more embodiments of the present application, in some embodiments, obtaining the first expansion force value of each battery cell based on the first formation step 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.

[0068] Specifically, in the embodiment of the present application, the pressure value corresponding to the formation process is in the range of [-15, -30] kPa, the first preset duration is in the range of [25, 35] seconds, the second preset duration is in the range of [5, 10] minutes, the first charging rate is 0.1C, the third preset duration is in the range of [20, 25] minutes, and the fourth preset duration is in the range of [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. In one example, the above-mentioned chemical process flow includes the following steps: 1) Rest 30s (rest for 30 seconds); 2) 0.1C CC 7min (0.1 charging rate, constant current charging for 7 minutes); 3) Rest 30s (rest for 30 seconds); 4) 0.1C CC 23min (0.1 charging rate, constant current charging for 23 minutes); 5) Rest 30s (rest for 30 seconds); 6) 0.3C CC 30min (0.3 charging rate, constant current charging for 30 minutes); 7) Rest 30s (rest for 30 seconds); 8) 0.3C CC 30min (0.3 charging rate, constant current charging for 30 minutes); 9) Rest 30s.

[0069] Among them, the above step 1) is used to monitor whether the open circuit voltage (OCV) of the cell after infiltration is normal; the above steps 2)-5) are used to form a stable and dense SEI layer through low-rate charging of the cell. After the cell reaches 5% SOC, adding 30s of rest time in the middle can help the gas inside the cell to be discharged. During the rest period, the chemical reaction inside the cell tends to balance, and the gas in the electrolyte can be discharged through the breathable structure of the cell.

[0070] In the above steps 6)-9), the battery cell is usually charged to 30% power through high-rate formation, and finally reaches 35% SOC. This process ensures that the battery cell is formed at a lower state of charge, avoiding damage to the battery cell caused by excessive voltage and current. Increasing the standing time by 30s can help discharge the gas inside the battery cell.

[0071] The embodiment of the present application can accurately capture the changes in the expansion force of the battery cell under different charge states by standing and charging in stages. Acquiring expansion force data during the formation process helps to identify potential battery cell abnormalities at an early stage, and based on actual measurement data, can also provide support for production quality control and process optimization of the battery cell.

[0072] In one or more embodiments of the present application, 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.

[0073] Specifically, in an embodiment of the present application, the third charging rate can be 0.5C, the fourth charging rate is 0.05C, the maximum charging voltage of the lithium iron phosphate battery (LFP) is 3.65V or 3.8V, and the ternary lithium battery (NCM), the maximum charging voltage of the NCM is 4.3V.

[0074] In one example, the capacity process flow includes the following steps: 1) Rest 30s (rest for 30 seconds); 2) 0.5C CC Vmax (0.5 charging rate, constant current charging to maximum charging voltage) 3) Vmax CV 0.05C (0.05 charging rate, constant voltage charging reduces the charging current to 0.05C until the battery cell reaches a fully charged state). Here, constant voltage charging can depolarize the battery cell.

[0075] The embodiment of the present application can accurately capture the changes in the expansion force of the battery cell at different charge states by standing and charging in stages. Acquiring expansion force data in the capacity process helps to identify potential battery cell abnormalities at an early stage, and based on actual measurement data, can also provide support for production quality control and process optimization of the battery cell.

[0076] In one or more embodiments of the present application, in some embodiments, obtaining 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.

[0077] Specifically, in the embodiment of the present application, the fourth state of charge may range from 99% SOC to 100% SOC, and the fifth state of charge may be 90% SOC. The step of discharging each battery cell to the fifth state of charge for aging includes: discharging the battery to a preset SOC for aging, for example, discharging 0.1CnAh at a rate of 0.5-1.0C, and discharging the battery cell to 90% SOC for aging.

[0078] The embodiment of the present application obtains the first expansion force value and the second expansion force value of the battery cell through the second formation process, and combined with the aging operation, can comprehensively evaluate the expansion force characteristics of the battery cell under different charge states and usage conditions. This method not only improves the detection accuracy of abnormal battery cells, but also provides an important basis for production quality control and process optimization of battery cells.

[0079] The embodiment of the present invention further provides a battery detection device, which is used to execute the battery detection method provided in the above embodiments. Figure 7 As shown, the device comprises: An acquisition unit 702 is used to acquire, for each of the plurality of battery cells, an expansion force value corresponding to each battery cell under different states of charge; The determination unit 704 is configured to determine whether there is an abnormal battery cell among the plurality of battery cells based on the expansion force value corresponding to each battery cell.

[0080] In the technical solution of the embodiment of the present invention, for each of the multiple battery cells in the mass production process, the expansion force value of each battery cell at different charge states is obtained; based on the expansion force value corresponding to each battery cell, it is determined whether there is an abnormal battery cell in the multiple battery cells. Compared with the method of using a prediction model to identify abnormal batteries in the related art, the present application can not only accurately and effectively identify the battery cells with abnormal battery cell expansion force in mass production batteries, but also reduce the dependence of the detection process on the battery cell type and structure, and has few limitations and high universality.

[0081] In one or more implementations of the present application, the acquisition unit 702 includes: The first acquisition module is used to obtain the first expansion force value and the second expansion force value of each battery cell; the first expansion force value is the peak expansion force of the battery cell when it is in a first state of charge range, the second expansion force value is the peak expansion force of the battery cell when it is in 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.

[0082] In one or more implementations of the present application, the determining unit 704 includes: A determination module is used to determine whether there is an abnormal battery cell among the multiple 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.

[0083] In one or more implementations of the present application, the determining module includes: A determination subunit is used to determine whether an abnormal battery cell exists among the multiple battery cells based on the presence of an expansion force outlier in a first expansion force set composed of the first expansion force values ​​corresponding to each battery cell, or based on the presence of an expansion force outlier in a second expansion force set composed of the second expansion force values ​​corresponding to each battery cell.

[0084] In one or more embodiments of the present application, the determining subunit includes: A first acquisition submodule, used to acquire a difference between the first expansion force value and the second expansion force value corresponding to each battery cell; The first determination submodule is used to determine that there is an abnormal battery cell among the multiple battery cells when an expansion force outlier value appears in the difference value set composed of the difference values.

[0085] In one or more embodiments of the present application, the determining subunit includes: A second acquisition submodule, used to acquire 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; A second determination submodule, configured to 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; A calculation submodule, used for calculating the difference between the first product and the second product corresponding to each battery cell; The third determination submodule is used to determine that there is an abnormal battery cell among the multiple battery cells when an expansion force outlier value appears in the difference set composed of the differences.

[0086] In one or more implementations of the present application, the acquisition unit 702 includes: A second acquisition module is used to acquire a first expansion force value of each battery cell based on a first formation process in a production process; the first formation process is used to make the battery cell be in the first state of charge range; The third acquisition module is used to acquire 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 be in the second state of charge range.

[0087] In one or more implementations of the present application, the second acquisition module includes: A first static charging subunit, used for placing each of the battery cells at rest for a first preset time, and performing constant current charging on each of the battery cells for a second preset time based on a first charging rate; A second static charging subunit, configured to place each of the battery cells at rest 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 the first state of charge, and place each of the battery cells at rest for the first preset time; A third static charging subunit is used to perform constant current charging on each of the battery cells for a fourth preset time period based on the second charging rate; and to place each of the battery cells at rest for the first preset time period; A fourth static charging subunit is used to perform constant current charging on the battery cells for a fourth preset time period based on the second charging rate, so that each battery cell reaches a third state of charge from the second state of charge, and to keep each battery cell static for the first preset time period; The first acquisition subunit is used to acquire a first expansion force value corresponding to each battery cell from the first state of charge to the third state of charge.

[0088] In one or more implementations of the present application, the third acquisition module includes: a fifth static charging subunit, configured to place each of the battery cells at rest for a first preset time, and perform 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; a static discharge sub-unit, used for 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 acquisition subunit is used to obtain the second expansion force value corresponding to each battery cell in the capacity process.

[0089] In one or more implementations of the present application, the acquiring unit 702 further includes: The fourth acquisition module is used to obtain the first expansion force value and the second expansion force value of each battery cell based on the 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.

[0090] Figure 8 8 is a logical structure block diagram of an electronic device according to an exemplary embodiment. For example, the electronic device 800 may be an electronic device such as a BMS, a vehicle controller, a motor controller, a domain controller, etc., which is disposed inside an electric device.

[0091] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory including instructions, and the above instructions can be executed by a battery processor to complete the above battery detection method, the method comprising: for each battery cell in a plurality of battery cells, obtaining the expansion force value of each battery cell at different states of charge; based on the expansion force value corresponding to each battery cell, determining whether there is an abnormal battery cell in the plurality of battery cells. Optionally, the above instructions can also be executed by the processor of the battery to complete the other steps involved in the above exemplary embodiment. For example, the non-transitory computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.

[0092] In an exemplary embodiment, an application / computer program product is also provided, including one or more instructions, which can be executed by a processor of a battery to complete the above-mentioned battery detection method, the method comprising: for each of a plurality of battery cells, obtaining the expansion force value of each battery cell at different states of charge; based on the expansion force value corresponding to each battery cell, determining whether there is an abnormal battery cell in the plurality of battery cells. Optionally, the above-mentioned instructions can also be executed by a processor of a battery to complete other steps involved in the above-mentioned exemplary embodiment. Figure 8 FIG. 8 is an example diagram of an electronic device 800. A person skilled in the art can understand that Figure 8 It is only an example of the electronic device 800 and does not constitute a limitation of the electronic device 800. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device 800 may also include input and output devices, network access devices, buses, etc.

[0093] The processor 802 may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A 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 uses various interfaces and lines to connect various parts of the entire electronic device 800.

[0094] The memory 801 can be used to store computer-readable instructions. The processor 802 implements various functions of the electronic device 800 by running or executing the computer-readable instructions or modules stored in the memory 801 and calling the data stored in the memory 801. The memory 801 can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area can store data created according to the use of the electronic device 800, etc. In addition, the memory 801 can include a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM) or other non-volatile / volatile storage devices.

[0095] If the module integrated in the electronic device 800 is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also instruct the relevant hardware to complete the computer-readable instructions through computer-readable instructions. The computer-readable instructions can be stored in a computer-readable storage medium, and when the computer-readable instructions are executed by the processor, the steps of the above-mentioned various method embodiments can be implemented.

[0096] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0097] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

[0098] The user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with the relevant laws, regulations and standards of relevant countries and regions, and provide corresponding operation entrances for users to choose to authorize or refuse.

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; Based on the first expansion force value and the second expansion force value corresponding to each battery cell, it is determined whether there is an abnormal battery cell among the plurality of battery cells.

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 any one of claims 1 to 3, characterized in that: The obtaining of the first expansion force value and the second expansion force value of each battery cell during the production process includes: Obtaining a first expansion force value of each battery cell based on a first formation process in a 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.

5. The method according to claim 4, 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.

6. The method according to claim 4, 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.

7. The method according to claim 4, 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.

8. 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; 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.

9. 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 7 through the computer program.

10. 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 7 when executed.

11. 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 7.

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