Battery cell consistency detection method, device, electronic device and storage medium

Abstract

The present application provides a method, device, electronic device and storage medium for detecting the consistency of a battery cell. The method includes obtaining multiple first battery cell voltages and multiple first battery cell capacities of multiple battery cells to be detected during the charging process; wherein the multiple battery cells to be detected are lithium iron phosphate battery cells; generating a first voltage-capacity curve corresponding to the battery cell to be detected based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell to be detected; and performing consistency detection on multiple battery cells to be detected based on the characteristic peak in the first voltage-capacity curve. The embodiment of the present application obtains the first battery cell voltage and the first battery cell capacity of the battery cell to be detected during the charging process, generates a first voltage-capacity curve based on the first battery cell voltage and the first battery cell capacity, and performs consistency detection according to the characteristic peak of the first voltage-capacity curve, so as to screen out battery cells with better consistency.

Description

Technical Field

[0001] The present application relates to the technical field of battery detection, and in particular to a method, device, electronic device and storage medium for detecting consistency of a battery cell. Background Art

[0002] After the battery cells are produced, even good quality ones have certain consistency differences. The initial inconsistency will accumulate as the battery cells are continuously charged and discharged during use, resulting in greater differences in the battery cell status. The use environment within the battery pack, such as temperature, is also different for each single cell, which causes the inconsistency of the single cells to gradually increase during use, so that in some cases the performance of some single cells decays faster, eventually causing the battery pack to fail prematurely. Therefore, before the battery pack is assembled, the single cells need to be tested for consistency, and the cells that meet the consistency requirements are assembled into the battery pack. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a method, device, electronic device and storage medium for detecting the consistency of a battery cell, so as to perform consistency detection on the battery cell.

[0004] In a first aspect, an embodiment of the present application provides a method for detecting consistency of a battery cell, comprising:

[0005] Acquire multiple first battery cell voltages and multiple first battery cell capacities of multiple battery cells to be tested during charging; wherein the multiple battery cells to be tested are lithium iron phosphate battery cells;

[0006] Generate a first voltage-capacity curve corresponding to the battery cell to be detected based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell to be detected;

[0007] Extracting the peak position, peak width, peak value and peak area corresponding to the characteristic peak in the first voltage-capacity curve;

[0008] The peak positions, peak widths, peak values ​​and peak areas corresponding to the multiple cells to be tested are compared to obtain consistency test results.

[0009] The embodiment of the present application obtains the first battery cell voltage and the first battery cell capacity of the battery cell to be tested during the charging process, generates a first voltage-capacity curve based on the first battery cell voltage and the first battery cell capacity, and performs consistency detection according to the characteristic peak of the first voltage-capacity curve, so as to screen out battery cells with better consistency.

[0010] In any embodiment, the peak positions, peak widths, peak values ​​and peak areas corresponding to the plurality of cells to be tested are compared to obtain a consistency test result, including:

[0011] Based on the first voltage-capacity curve, extracting the peak position, peak width, peak value and peak area of ​​each characteristic peak;

[0012] Calculate the differences between the peak position, peak width, peak value and peak area of ​​the same characteristic peak in any two cells to be tested;

[0013] Calculate the difference based on the difference and the influence factor of the corresponding characteristic peak;

[0014] Perform consistency test on any two cells to be tested based on the difference.

[0015] In the embodiment of the present application, for the lithium iron phosphate battery cell, the peak position, peak width, peak value and peak area of ​​different characteristic peaks in its first voltage capacity curve can characterize the lithium insertion ability of the battery cell to different degrees. Therefore, for any two battery cells to be tested, the difference corresponding to the peak position, peak width, peak value and peak area of ​​each characteristic peak can be calculated, and the difference degree can be calculated based on the difference and the influencing factor. According to the difference degree, it can be quickly and accurately determined whether the two battery cells to be tested are consistent.

[0016] In any embodiment, generating a first voltage-capacity curve corresponding to the battery cell to be detected based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell to be detected includes:

[0017] Determine a voltage-capacity differential value according to the first battery cell voltage and the first battery cell capacity;

[0018] A first voltage-capacity curve is generated by taking the first battery cell capacity as the horizontal coordinate and the voltage-capacity differential value as the vertical coordinate.

[0019] The embodiment of the present application generates a first voltage-capacity curve. The characteristic peak in the first voltage-capacity curve can reflect the lithium insertion capability of the battery cell to be tested. The consistency of the battery cell to be tested can be tested through the lithium insertion capability.

[0020] In any embodiment, the method further comprises:

[0021] Select multiple battery cells to be selected, and perform cyclic charge and discharge on the multiple battery cells to be selected until the health status of the multiple battery cells to be selected reaches a preset health status, and record the number of cycles of the battery cells to be selected and the voltage and capacity of the second battery cell during the cyclic charge and discharge process;

[0022] Determine a standard battery cell from a plurality of candidate battery cells based on the number of cycles;

[0023] generating a second voltage-capacity curve based on a second battery cell voltage and a second battery cell capacity of the standard battery cell;

[0024] Accordingly, the peak positions, peak widths, peak values ​​and peak areas corresponding to the multiple cells to be tested are compared to obtain consistency test results, including:

[0025] The peak positions, peak widths, peak values ​​and peak areas corresponding to the characteristic peaks of the battery cell to be tested are compared with those of the characteristic peaks in the second voltage-capacity curve corresponding to the standard battery cell, so as to achieve consistency detection of the battery cell to be tested.

[0026] In the embodiment of the present application, the standard battery cells are determined in advance, and then the standard battery cells are used to perform consistency detection on the battery cells to be detected, so that the battery cells consistent with the standard battery cells can be screened out from the battery cells to be detected for assembly.

[0027] In any embodiment, the method further comprises:

[0028] The plurality of cells to be tested are charged at a preset rate; the preset rate is less than or equal to 0.1C.

[0029] The embodiment of the present application charges the battery cell to be tested by charging at a low rate, thereby reducing the polarization effect during the charging process, so that the difference between the first battery cell voltage and the first battery cell capacity collected during the charging process is derived from the graphite anode, thereby improving the accuracy of consistency detection.

[0030] In any embodiment, the method further comprises:

[0031] Obtaining the internal resistance of multiple cells to be tested during the charging and discharging process;

[0032] Based on the first cell voltage and the cell internal resistance corresponding to each cell to be detected, generating a voltage-internal resistance curve corresponding to the cell to be detected;

[0033] The first voltage capacity curve and the voltage internal resistance curve are feature extracted through the consistency detection model to obtain curve features, and the consistency detection result is obtained based on the curve features.

[0034] The embodiment of the present application detects the consistency of the battery cell to be detected by combining the voltage internal resistance curve and the voltage capacity curve of the battery cell to be detected, thereby improving the accuracy of the detection.

[0035] In any embodiment, the battery cell to be tested is a battery cell that has not been used after production.

[0036] In the embodiment of the present application, since fresh, unused battery cells have not yet experienced loss of active lithium and loss of negative electrode material, the characteristic peak difference of the first voltage-capacity curve corresponding to the unused battery cells can represent the difference in negative electrode lithium insertion capacity caused by graphite itself or process differences. Therefore, the first voltage-capacity curve can be used to quickly and accurately detect the consistency of the battery cells to be tested.

[0037] In a second aspect, an embodiment of the present application provides a battery cell consistency detection device, comprising:

[0038] A data acquisition module, used to acquire a plurality of first battery cell voltages and a plurality of first battery cell capacities of a plurality of battery cells to be detected during charging; wherein the plurality of battery cells to be detected are lithium iron phosphate battery cells;

[0039] A curve generating module, used for generating a first voltage-capacity curve corresponding to the battery cell to be detected based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell;

[0040] A feature extraction module, used to extract the peak position, peak width, peak value and peak area corresponding to the characteristic peak in the first voltage-capacity curve;

[0041] The detection module is used to compare the peak positions, the peak widths, the peak values ​​and the peak areas respectively corresponding to the multiple cells to be detected to obtain a consistency detection result.

[0042] In a third aspect, an embodiment of the present application provides an electronic device, including: a processor, a memory, and a bus, wherein:

[0043] The processor and the memory communicate with each other via a bus;

[0044] The memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the method of the first aspect.

[0045] In a fourth aspect, an embodiment of the present application provides a non-transitory computer-readable storage medium, including:

[0046] The non-transitory computer-readable storage medium stores computer instructions, which cause a computer to execute the method of the first aspect.

[0047] In a fifth aspect, an embodiment of the present application provides a computer program product, comprising computer program instructions, which, when read and executed by a processor, execute the method of the first aspect.

[0048] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by practicing the embodiments of the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0050] Figure 1 A schematic diagram of a flow chart of a method for detecting consistency of a battery cell provided in an embodiment of the present application;

[0051] Figure 2 A first voltage-capacity curve diagram provided in an embodiment of the present application;

[0052] Figure 3 A schematic diagram of the structure of a battery cell consistency detection device provided in an embodiment of the present application;

[0053] Figure 4 A schematic diagram of the physical structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0054] The following embodiments of the technical solution of the present application will be 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.

[0055] 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.

[0056] In the description of the embodiments of the present application, 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 application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0057] 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.

[0058] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can 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.

[0059] In the description of the embodiments of the present application, 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).

[0060] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0061] A battery module or battery pack is assembled by connecting multiple cells in series or in parallel, and then the battery module or battery pack is assembled in a new energy vehicle or other usage environment to supply power to the outside. Since the performance consistency of the cells in a battery module or battery pack has a great impact on the overall electrical performance, it is beneficial to integrate batteries with small performance deviations to build high-performance battery modules by screening out cells with poor consistency in advance.

[0062] Lithium-ion batteries produced in the same batch may show differences in lithium ion diffusion and storage, which is mainly related to the lithium deintercalation of graphite anodes. In addition to being affected by the consistency of graphite powder, the impact of the manufacturing process cannot be ignored. For example, uneven coating and the aggregation of binders during the drying process of the pole pieces will disrupt the uniform embedding of lithium ions in graphite. Under the interference of these multiple factors, lithium ion deintercalation is affected, thus accelerating the decay of capacity.

[0063] The battery cell consistency detection method, device, electronic device and storage medium provided in the embodiments of the present application can charge the battery cell and record the charging data during the charging process, generate a curve that can characterize the lithium embedding capacity of the battery cell based on the charging data, and then perform consistency detection of the battery cell based on the curve. Provide data reference for the subsequent assembly of the battery cell into a battery module or battery pack. It can be understood that the battery cell in the embodiments of the present application refers to the battery cell that constitutes the power battery, and the battery cell can be a lithium iron phosphate battery cell.

[0064] Figure 1 A schematic diagram of a cell consistency detection method provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the method includes:

[0065] Step 101: obtaining a plurality of first battery cell voltages and a plurality of first battery cell capacities of a plurality of battery cells to be tested during a charging process;

[0066] Step 102: generating a first voltage-capacity curve corresponding to the battery cell to be detected based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell to be detected;

[0067] Step 103: extracting the peak position, peak width, peak value and peak area corresponding to the characteristic peak in the first voltage-capacity curve;

[0068] Step 104: Compare the peak positions, peak widths, peak values ​​and peak areas corresponding to the multiple cells to be tested to obtain consistency test results.

[0069] In the specific implementation process, the consistency detection of battery cells refers to the measurement and comparison of the performance parameters of each battery cell (such as capacity, internal resistance, open circuit voltage, etc.) to ensure their similarity within a certain range. The purpose of battery cell consistency detection is to enable the individual battery cells that constitute the battery module or battery pack to work together during the charging and discharging process to avoid the performance degradation of the entire battery module or battery pack due to differences in the performance of individual battery cells. Inconsistent battery cells may cause some battery cells in the battery module or battery pack to be overcharged or over-discharged, thereby accelerating aging, reducing the service life of the battery pack, and may cause safety problems. Therefore, the multiple battery cells to be tested are battery cells of the same specification and model, and further, they can be battery cells produced in the same batch or in different batches. In addition, the multiple battery cells to be tested are lithium iron phosphate battery cells.

[0070] When the consistency test is performed on the battery cells to be tested, multiple battery cells to be tested can be charged by a charging device, wherein the charging device includes but is not limited to an electrochemical workstation. In addition, the charging parameters of the multiple battery cells to be tested are the same. The charging parameters include but are not limited to the charging rate, charging current, charging cut-off voltage, charging cut-off battery state of charge (SOC), and temperature.

[0071] During the charging process of the battery cell to be tested, the first battery cell voltage and the first battery cell capacity of each battery cell to be tested can be collected. The collection frequency can be set according to the actual situation, for example: the first battery cell voltage and the first battery cell capacity are collected every 0.5 seconds, 1 second, and 2 seconds. Therefore, for a battery cell to be tested, multiple first battery cell voltages and first battery cell capacities during the charging process can be obtained.

[0072] After obtaining multiple first cell voltages and multiple first cell capacities corresponding to each cell to be tested, a first voltage-capacity curve corresponding to the cell to be tested is generated based on the first cell voltage and the first cell capacity. Based on the first voltage-capacity curve, its peak position, peak width, peak value and peak area can be extracted. Among them, the peak position refers to the specific position of the characteristic peak on the voltage-capacity curve, which usually corresponds to a specific voltage point of the cell during charging or discharging. The stability of the peak position can reflect the stability of the cell performance. The peak width refers to the width of the characteristic peak on the voltage-capacity curve, which reflects the performance changes of the cell within a specific voltage range. The peak area refers to the area under the characteristic peak under the voltage-capacity curve, which reflects the amount of electricity stored or released by the cell within a specific voltage range. The peak value is used to characterize the ability of graphite to embed lithium.

[0073] Therefore, the embodiment of the present application obtains a consistency test result by extracting the peak position, peak width, peak value and peak area from the first voltage capacity curve of each battery cell to be tested, and comparing them with the peak position, peak width, peak value and peak area of ​​other battery cells to be tested.

[0074] When making a comparison, corresponding weights can be set according to the influence of peak position, peak width, peak value and peak area on consistency detection. For any two cells to be tested, the peak position, peak width, peak value and peak area are subtracted and multiplied by the corresponding weights to obtain a similarity score, and the consistency detection result is determined based on the similarity score. If the similarity score is greater than the preset threshold, it means that the two cells to be tested are consistent, otherwise it means that the two cells to be tested are not consistent.

[0075] The embodiment of the present application obtains the first battery cell voltage and the first battery cell capacity of the battery cell to be tested during the charging process, generates a first voltage-capacity curve based on the first battery cell voltage and the first battery cell capacity, and performs consistency detection according to the characteristic peak of the first voltage-capacity curve, so as to screen out battery cells with better consistency.

[0076] On the basis of the above embodiment, the peak positions, peak widths, peak values ​​and peak areas corresponding to the multiple cells to be tested are compared to obtain consistency test results, including:

[0077] Based on the first voltage-capacity curve, extracting the peak position, peak width, peak value and peak area of ​​each characteristic peak;

[0078] Calculate the differences between the peak position, peak width, peak value and peak area of ​​the same characteristic peak in any two cells to be tested;

[0079] Calculate the difference based on the difference and the influence factor of the corresponding characteristic peak;

[0080] Perform consistency test on any two cells to be tested based on the difference.

[0081] In the specific implementation process, for the lithium iron phosphate battery cell, the corresponding first voltage capacity curve generally includes three characteristic peaks, such as Figure 2 As shown in the figure, since the lithium iron phosphate battery cell changes between two phases during the delithiation process, there is no obvious phase change peak. Figure 2 The three characteristic peaks in the figure are all graphite characteristic peaks. During the charging process, due to lithium insertion, graphite is successively converted into LiC24, LiC12, and LixC6 (x=0.58-1). The three peaks in the figure represent the above-mentioned phase change process of graphite. The quality of graphite lithium insertion ability will affect the intensity of the characteristic peak. Since the intensity of the characteristic peak will be affected by the loss of active lithium and the loss of negative electrode material during the cycle / storage process, and the fresh battery cell has not yet experienced active lithium loss and negative electrode material loss, the difference in the characteristic peaks of the fresh battery cell can represent the difference in the negative electrode lithium insertion ability caused by the graphite itself or the process difference. The weak intensity of the characteristic peak represents the weak lithium insertion ability and the subsequent cycle performance is also poor. The most affected by the lithium insertion ability of graphite is characteristic peak 1, followed by characteristic peak 2, and finally characteristic peak 3. When performing consistency detection, the peak position, peak width, peak value and peak area of ​​these three characteristic peaks can be extracted respectively. Then, for any two cells to be tested, the peak positions of the same characteristic peaks of the two cells to be tested can be compared to obtain the peak position deviation; the peak widths of the same characteristic peaks can be compared to obtain the peak width deviation; the peak values ​​of the same characteristic peaks can be compared to obtain the peak deviation; the peak areas of the same characteristic peaks can be compared to obtain the peak area deviation. The weights corresponding to the peak position, peak width, peak value and peak area can be pre-set, and the characteristic peak deviation corresponding to the characteristic peak can be calculated based on the peak position deviation, peak width deviation, peak deviation and peak area deviation, as well as the weights corresponding to each. Each characteristic peak also corresponds to a characteristic peak weight, and a consistency score is determined based on the characteristic peak deviation and the characteristic peak weight. If the consistency score is greater than the preset value, it is determined that the two cells to be tested are consistent, otherwise it is determined that the two cells to be tested are not consistent. The consistency test is performed on the two cells to be tested in the above manner, and the final consistency test result can be obtained.

[0082] In another embodiment, characteristic peak 1 of the characteristic peaks of each battery cell to be tested can be used as the target characteristic peak, and the peak positions, peak widths, peak values ​​and peak areas of the characteristic peaks 1 corresponding to the two battery cells to be tested can be compared, and then weighted summed with pre-set weights to obtain a consistency score, and then the consistency test results of the two battery cells to be tested can be determined based on the consistency score.

[0083] In the embodiment of the present application, for the lithium iron phosphate battery cell, the target characteristic peak in its first voltage-capacity curve can reflect the lithium insertion ability of the battery cell to be tested. Therefore, the consistency of the battery cell to be tested can be accurately and quickly detected through the peak value of the target characteristic peak.

[0084] On the basis of the above embodiment, generating a first voltage-capacity curve corresponding to the battery cell to be detected based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell to be detected includes:

[0085] Determine a voltage-capacity differential value according to the first battery cell voltage and the first battery cell capacity;

[0086] A first voltage-capacity curve is generated by taking the first battery cell capacity as the horizontal coordinate and the voltage-capacity differential value as the vertical coordinate.

[0087] In a specific implementation process, after obtaining multiple first battery cell voltages and multiple first battery cell capacities corresponding to each battery cell to be tested, the voltage-capacity differential value of the first battery cell voltage and the first battery cell capacity can be calculated. For example: the first battery cell voltage is represented by V, and the first battery cell capacity is represented by Q, then the voltage-capacity differential value is dV / dQ.

[0088] The first cell capacity is used as the horizontal coordinate, and the voltage capacity differential value is used as the vertical coordinate to form a first voltage capacity curve, such as Figure 2 shown.

[0089] It is understandable that the first voltage-capacity curves corresponding to multiple cells to be tested can be displayed in the same coordinate graph to facilitate comparison of the peak values ​​of characteristic peaks in the first voltage-capacity curves. It is also possible to have a separate graph for the first voltage-capacity curve corresponding to each cell to be tested, and by determining the peak value of the characteristic peak in the first voltage-capacity curve from each graph and then comparing the peak values, consistency detection of the cells to be tested can be achieved.

[0090] The embodiment of the present application generates a first voltage-capacity curve. The characteristic peak in the first voltage-capacity curve can reflect the lithium insertion capability of the battery cell to be tested. The consistency of the battery cell to be tested can be tested through the lithium insertion capability.

[0091] Based on the above embodiment, the method further includes:

[0092] Select multiple battery cells to be selected, and perform cyclic charge and discharge on the multiple battery cells to be selected until the health status of the multiple battery cells to be selected reaches a preset health status, and record the number of cycles of the battery cells to be selected and the voltage and capacity of the second battery cell during the cyclic charge and discharge process;

[0093] generating a second voltage-capacity curve based on the second battery cell voltage and the second battery cell capacity;

[0094] Determine a standard battery cell from a plurality of candidate battery cells based on the number of cycles;

[0095] Accordingly, the peak positions, peak widths, peak values ​​and peak areas corresponding to the multiple cells to be tested are compared to obtain consistency test results, including:

[0096] The peak positions, peak widths, peak values ​​and peak areas corresponding to the characteristic peaks of the battery cell to be tested are compared with those of the characteristic peaks in the second voltage-capacity curve corresponding to the standard battery cell, so as to achieve consistency detection of the battery cell to be tested.

[0097] In a specific implementation process, when performing consistency testing on the battery cell to be tested, relevant parameters of the standard battery cell can be determined in advance, and then the relevant parameters of the battery cell to be tested are compared with relevant parameters of the standard battery cell to determine whether the battery cell to be tested meets the consistency requirements.

[0098] Among them, the method for determining the standard battery cell is as follows:

[0099] Graphite produced in different batches and cells to be selected produced on different dates are selected, wherein the number of cells to be selected includes but is not limited to 10. It can be understood that the more cells to be selected, the more accurate the determined standard cells are, and accordingly, the workload is also large. Therefore, the number of cells to be selected can be set according to actual needs. The cell capacity of the cell to be selected is 45Ah. The selected cell to be selected is charged at a small rate current (for example, 0.05C), with a cut-off voltage of 3.5V. The second cell voltage and the second cell capacity of the charging process are recorded at a time interval of 10min. After 30min of suspension, it is discharged at 1 / 3C to 2.5V. The battery is charged and discharged in this way until the health state of the cell to be selected is cycled to 80% SOH cut-off. According to dV / dQ, the height data h1 of characteristic peak 1, the height data h2 of characteristic peak 2, and the height data h3 of characteristic peak 3 are obtained, which are summarized in Table 1. It should be noted that for the convenience of description, only the peak values ​​(i.e., the height data of the characteristic peaks) are listed in Table 1 in the embodiments of the present application. In practical applications, the peak positions, peak widths, and peak areas of the three characteristic peaks can also be listed, and their standard values ​​can be determined. Since the development target of the selected battery cell is 1630cycle@80%SOH, the No. 1 battery cell closest to this target is selected as the standard battery cell, with the h1 standard of 0.0145, the h2 standard of 0.0115, and the h3 standard of 0.006. It should be noted that each model of battery cell will set its development target during the research and development stage.

[0100] Table 1

[0101]

[0102] After the standard cell is determined from multiple candidate cells, the consistency of the cell to be tested is tested using the standard cell as follows:

[0103] Charge multiple cells to be tested at a low rate current (e.g. 0.05C) with a cut-off voltage of 3.5V. Record the battery voltage and battery capacity during the charging process at 10-minute intervals. After 30 minutes of storage, discharge at 1 / 3C to 2.5V. The data collection is shown in the following table:

[0104] Table 2

[0105]

[0106] For comparison purposes, only the peak values ​​are compared here. The cells to be tested in the above table meet the h1, h2, h3 ≥ h1 standards, the h2 standard, and the h3 standards are 1, 4, 5, 6, 9, and 10, so these 6 cells to be tested meet the cell consistency.

[0107] It should be noted that in addition to the above consistency detection standards, other detection standards can also be set. For example, since h1=h1 standard, h2=h2 standard, and h3=h3 standard of the cells to be detected 9 and 10, the cells to be detected 9 and 10 meet the cell consistency. Of course, the peak values ​​of each characteristic peak and the influence factor can also be weighted and summed according to the above embodiment, and the weighted summed value can be used to perform consistency detection on the cells to be detected.

[0108] In the embodiment of the present application, the standard battery cells are determined in advance, and then the standard battery cells are used to perform consistency detection on the battery cells to be detected, so that the battery cells consistent with the standard battery cells can be screened out from the battery cells to be detected for assembly.

[0109] On the basis of the above embodiment, when charging the battery cell to be tested, in order to reduce the polarization effect during the charging process, a preset rate can be selected for charging, and the preset rate is less than or equal to 0.1C, so that the data difference during the charging process comes from the graphite anode.

[0110] The battery cell to be tested can be a fresh battery cell that has not been used after production. Since the fresh, unused battery cell has not yet experienced loss of active lithium and negative electrode material, the characteristic peak difference of the first voltage-capacity curve corresponding to the unused battery cell can represent the difference in negative electrode lithium insertion capacity caused by graphite itself or process differences. Therefore, the consistency test of the battery cell to be tested can be performed quickly and accurately through the first voltage-capacity curve.

[0111] Based on the above embodiment, the method further includes:

[0112] Obtaining the internal resistance of multiple cells to be tested during the charging and discharging process;

[0113] Based on the first cell voltage and the cell internal resistance corresponding to each cell to be detected, generating a voltage-internal resistance curve corresponding to the cell to be detected;

[0114] The first voltage capacity curve and the voltage internal resistance curve are feature extracted through the consistency detection model to obtain curve features, and the consistency detection result is obtained based on the curve features.

[0115] In the specific implementation process, the internal resistance of the battery cell is one of the important indicators of battery cell performance. It reflects the conductivity and charge transfer capacity inside the battery cell, and is closely related to the health of the battery cell. By combining the internal resistance data of the battery cell, the information dimension of consistency detection can be further enriched, so as to more comprehensively evaluate the consistency and performance differences of the battery cell. The internal resistance of the battery cell corresponding to multiple battery cells to be tested during the charging and discharging process can be obtained, the voltage of the battery cell and the internal resistance of the battery cell can be aligned, and the internal resistance of the battery cell corresponding to different battery cell voltages during the charging and discharging process can be obtained. Then, the voltage-internal resistance curve is generated based on the internal resistance of the battery cell corresponding to different battery cell voltages.

[0116] The first voltage capacity curve and the voltage internal resistance curve are input into the consistency detection model, and the consistency detection model extracts features from the two curves to obtain curve features; wherein the curve features may include relevant information about characteristic peaks corresponding to the two curves. After obtaining the curve features, the similarity between multiple cells to be tested can be calculated based on the curve features. The higher the similarity, the better the consistency. Thus, the consistency detection result can be obtained.

[0117] It is understandable that the similarity calculation method includes but is not limited to Euclidean distance and Manhattan distance.

[0118] The embodiment of the present application detects the consistency of the battery cell to be detected by combining the voltage internal resistance curve and the voltage capacity curve of the battery cell to be detected, thereby improving the accuracy of the detection.

[0119] Figure 3 This is a schematic diagram of the structure of a cell consistency detection device provided in an embodiment of the present application. The device may be a module, program segment or code on an electronic device. It should be understood that the device is similar to the above-mentioned Figure 1 The method embodiment corresponds to and can be executed Figure 1 The various steps involved in the method embodiment and the specific functions of the device can be found in the above description. To avoid repetition, detailed description is appropriately omitted here. The device includes: a data acquisition module 301, a curve generation module 302, a feature extraction module 303 and a detection module 304, wherein:

[0120] The data acquisition module 301 is used to acquire a plurality of first battery cell voltages and a plurality of first battery cell capacities of a plurality of battery cells to be detected during the charging process; wherein the plurality of battery cells to be detected are lithium iron phosphate battery cells;

[0121] The curve generating module 302 is used to generate a first voltage-capacity curve corresponding to the battery cell to be detected based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell;

[0122] The feature extraction module 303 is used to extract the peak position, peak width, peak value and peak area corresponding to the characteristic peak in the first voltage-capacity curve;

[0123] The detection module 304 is used to compare the peak positions, the peak widths, the peak values ​​and the peak areas respectively corresponding to the multiple cells to be detected to obtain a consistency detection result.

[0124] Based on the above embodiment, the detection module 304 is specifically used for:

[0125] Based on the first voltage-capacity curve, extracting the peak position, the peak width, the peak value and the peak area of ​​each characteristic peak;

[0126] Calculating the differences between the peak position, the peak width, the peak value and the peak area of ​​the same characteristic peak in any two of the cells to be tested;

[0127] Calculating the difference according to the difference and the influence factor of the corresponding characteristic peak;

[0128] Based on the difference, consistency detection is performed on any two cells to be detected.

[0129] Based on the above embodiment, the curve generating module 302 is specifically used for:

[0130] Determine a voltage-capacity differential value according to the first battery cell voltage and the first battery cell capacity;

[0131] The first voltage-capacity curve is generated by taking the first battery cell capacity as the horizontal coordinate and the voltage-capacity differential value as the vertical coordinate.

[0132] Based on the above embodiment, the device further includes a standard battery cell determination module, which is used to:

[0133] Selecting a plurality of battery cells to be selected, and performing cyclic charge and discharge on the plurality of battery cells to be selected until the health status of the plurality of battery cells to be selected reaches a preset health status, and recording the number of cycles of the battery cells to be selected and the voltage of the second battery cell and the capacity of the second battery cell during the cyclic charge and discharge process;

[0134] Determine a standard battery cell from a plurality of battery cells to be selected based on the number of cycles;

[0135] Generate a second voltage-capacity curve based on a second battery cell voltage and a second battery cell capacity corresponding to the standard battery cell;

[0136] Accordingly, the detection module 304 is specifically used for:

[0137] The peak positions, peak widths, peak values ​​and peak areas corresponding to the characteristic peaks of the battery cell to be tested are compared with those of the characteristic peaks in the second voltage-capacity curve corresponding to the standard battery cell, so as to achieve consistency detection of the battery cell to be tested.

[0138] Based on the above embodiment, the device further includes a charging module, which is used to:

[0139] The plurality of cells to be tested are charged at a preset rate; the preset rate is less than or equal to 0.1C.

[0140] On the basis of the above embodiment, the device further includes a voltage internal resistance curve generating module, which is used to:

[0141] Obtaining the internal resistance of the multiple cells to be tested during the charging and discharging process;

[0142] Based on the first battery cell voltage and the battery cell internal resistance corresponding to each battery cell to be detected, generating a voltage-internal resistance curve corresponding to the battery cell to be detected;

[0143] The first voltage capacity curve and the voltage internal resistance curve are feature extracted by a consistency detection model to obtain curve features, and a consistency detection result is obtained based on the curve features.

[0144] Based on the above embodiment, the battery cell to be tested is a battery cell that has not been used after production.

[0145] Figure 4 A schematic diagram of the physical structure of an electronic device provided in an embodiment of the present application, such as Figure 4 As shown, the electronic device includes: a processor (processor) 401, a memory (memory) 402 and a bus 403; wherein,

[0146] The processor 401 and the memory 402 communicate with each other via the bus 403;

[0147] The processor 401 is used to call the program instructions in the memory 402 to execute the methods provided by the above-mentioned method embodiments, for example, including: obtaining multiple first battery cell voltages and multiple first battery cell capacities of multiple battery cells to be tested during the charging process; wherein the multiple battery cells to be tested are lithium iron phosphate battery cells; generating a first voltage-capacity curve corresponding to the battery cell to be tested based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell to be tested; extracting the peak position, peak width, peak value and peak area corresponding to the characteristic peak in the first voltage-capacity curve; comparing the peak positions, peak widths, peak values ​​and peak areas corresponding to the multiple battery cells to be tested to obtain a consistency test result.

[0148] The processor 401 may be an integrated circuit chip with signal processing capability. The processor 401 may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. It may implement or execute various methods, steps and logic block diagrams disclosed in the embodiments of the present application. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0149] The memory 402 may include, but is not limited to, random access memory (RAM), read only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.

[0150] The present embodiment discloses a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute the methods provided by the above-mentioned method embodiments, for example, including: obtaining multiple first battery cell voltages and multiple first battery cell capacities of multiple battery cells to be tested during the charging process; wherein the multiple battery cells to be tested are lithium iron phosphate battery cells; generating a first voltage-capacity curve corresponding to the battery cell to be tested based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell to be tested; extracting the peak position, peak width, peak value and peak area corresponding to the characteristic peak in the first voltage-capacity curve; comparing the peak positions, peak widths, peak values ​​and peak areas corresponding to the multiple battery cells to be tested, to obtain a consistency test result.

[0151] The present embodiment provides a non-transitory computer-readable storage medium, which stores computer instructions, and the computer instructions enable the computer to execute the methods provided by the above-mentioned method embodiments, for example, including: obtaining multiple first battery cell voltages and multiple first battery cell capacities of multiple battery cells to be tested during the charging process; wherein the multiple battery cells to be tested are lithium iron phosphate battery cells; generating a first voltage-capacity curve corresponding to the battery cell to be tested based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell to be tested; extracting the peak position, peak width, peak value and peak area corresponding to the characteristic peak in the first voltage-capacity curve; comparing the peak positions, peak widths, peak values ​​and peak areas corresponding to the multiple battery cells to be tested, to obtain a consistency test result.

[0152] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0153] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0154] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0155] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0156] The above description is only an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for detecting consistency of a battery cell, characterized in that: include: Acquire multiple first battery cell voltages and multiple first battery cell capacities of multiple battery cells to be detected during charging; wherein the multiple battery cells to be detected are lithium iron phosphate battery cells; Generate a first voltage-capacity curve corresponding to the battery cell to be detected based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell to be detected; Extracting the peak position, peak width, peak value and peak area corresponding to the characteristic peak in the first voltage-capacity curve; Compare the peak positions, the peak widths, the peak values ​​and the peak areas respectively corresponding to the multiple cells to be tested to obtain a consistency test result; The step of comparing the peak positions, the peak widths, the peak values ​​and the peak areas respectively corresponding to the plurality of cells to be tested to obtain a consistency test result includes: Based on the first voltage-capacity curve, extracting the peak position, the peak width, the peak value and the peak area of ​​each characteristic peak; Calculating the differences between the peak position, the peak width, the peak value and the peak area of ​​the same characteristic peak in any two of the cells to be tested; Calculating the difference according to the difference and the influence factor of the corresponding characteristic peak; Performing consistency detection on any two cells to be detected based on the difference; The calculating the difference degree according to the difference and the influence factor of the corresponding characteristic peak includes: Obtaining weights corresponding to the peak position, the peak width, the peak value and the peak area respectively; Obtaining characteristic peak deviation based on the difference and weight corresponding to the peak position, the peak width, the peak value and the peak area, respectively; The difference is obtained by calculation according to the characteristic peak deviation and the corresponding characteristic peak weight.

2. The method according to claim 1, characterized in that The generating a first voltage-capacity curve corresponding to the battery cell to be detected based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell to be detected includes: Determine a voltage-capacity differential value according to the first battery cell voltage and the first battery cell capacity; The first voltage-capacity curve is generated by taking the first battery cell capacity as the horizontal coordinate and the voltage-capacity differential value as the vertical coordinate.

3. The method according to claim 1, characterized in that The method further comprises: Selecting a plurality of battery cells to be selected, and performing cyclic charge and discharge on the plurality of battery cells to be selected until the health status of the plurality of battery cells to be selected reaches a preset health status, and recording the number of cycles of the battery cells to be selected and the voltage of the second battery cell and the capacity of the second battery cell during the cyclic charge and discharge process; Determine a standard battery cell from a plurality of battery cells to be selected based on the number of cycles; Generate a second voltage-capacity curve based on a second battery cell voltage and a second battery cell capacity corresponding to the standard battery cell; Accordingly, the peak positions, the peak widths, the peak values ​​and the peak areas respectively corresponding to the plurality of cells to be tested are compared to obtain a consistency test result, including: The peak positions, peak widths, peak values ​​and peak areas corresponding to the characteristic peaks of the battery cell to be tested are compared with those of the characteristic peaks in the second voltage-capacity curve corresponding to the standard battery cell, so as to achieve consistency detection of the battery cell to be tested.

4. The method according to claim 1, characterized in that The method further comprises: The plurality of cells to be tested are charged at a preset rate; the preset rate is less than or equal to 0.1C.

5. The method according to claim 1, characterized in that The method further comprises: Obtaining the internal resistance of the multiple cells to be tested during the charging and discharging process; Based on the first battery cell voltage and the battery cell internal resistance corresponding to each battery cell to be detected, generating a voltage-internal resistance curve corresponding to the battery cell to be detected; The first voltage capacity curve and the voltage internal resistance curve are feature extracted by a consistency detection model to obtain curve features, and a consistency detection result is obtained based on the curve features.

6. The method according to any one of claims 1 to 5, characterized in that: The battery cells to be tested are battery cells that have not been used after production.

7. A battery cell consistency detection device, characterized in that: include: A data acquisition module, used to acquire a plurality of first battery cell voltages and a plurality of first battery cell capacities of a plurality of battery cells to be detected during charging; wherein the plurality of battery cells to be detected are lithium iron phosphate battery cells; A curve generating module, used for generating a first voltage-capacity curve corresponding to the battery cell to be detected based on the first battery cell voltage and the first battery cell capacity corresponding to each battery cell; A feature extraction module, used to extract the peak position, peak width, peak value and peak area corresponding to the characteristic peak in the first voltage-capacity curve; A detection module, used for comparing the peak positions, the peak widths, the peak values ​​and the peak areas respectively corresponding to the multiple cells to be detected to obtain a consistency detection result; The detection module is specifically used for: Based on the first voltage-capacity curve, extracting the peak position, the peak width, the peak value and the peak area of ​​each characteristic peak; Calculating the differences between the peak position, the peak width, the peak value and the peak area of ​​the same characteristic peak in any two of the cells to be tested; Calculating the difference according to the difference and the influence factor of the corresponding characteristic peak; Performing consistency detection on any two cells to be detected based on the difference; The calculating the difference degree according to the difference and the influence factor of the corresponding characteristic peak includes: Obtaining weights corresponding to the peak position, the peak width, the peak value and the peak area respectively; Obtaining characteristic peak deviation based on the difference and weight corresponding to the peak position, the peak width, the peak value and the peak area, respectively; The difference is obtained by calculation according to the characteristic peak deviation and the corresponding characteristic peak weight.

8. An electronic device, characterized in that: include: processor, memory and bus, wherein, The processor and the memory communicate with each other via the bus; The memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the method according to any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium, characterized in that: The non-transitory computer-readable storage medium stores computer instructions, which, when executed by a computer, cause the computer to perform the method according to any one of claims 1 to 6.

10. A computer program product, characterized in that The method comprises computer program instructions, and when the computer program instructions are read and executed by a processor, the method according to any one of claims 1 to 6 is executed.

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