Cell capacity assessment methods, devices, storage media and computer program products

Abstract

This application provides a cell capacity evaluation method, apparatus, storage medium, and computer program product, relating to the field of battery technology. The cell capacity evaluation method includes: performing a first discharge test on a first cell and a second cell according to a preset discharge strategy; performing at least one storage process on the first cell and the second cell according to a preset storage strategy, and after each storage process, performing a second discharge test on the first cell and the second cell according to the discharge strategy; after the second discharge test, obtaining second discharge capacity information corresponding to the first cell; and determining capacity loss information corresponding to the first cell and reversible capacity loss information corresponding to the negative electrode OH region based on the first and second discharge capacity information. This application improves the accuracy and reliability of capacity evaluation for cells with a negative electrode OH region.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a cell capacity evaluation method, apparatus, storage medium, and computer program product. Background Technology

[0002] Lithium-ion batteries are currently widely used in new energy vehicles, consumer electronics, and energy storage systems. Lithium-ion battery cells face the risk of lithium plating during charging. To suppress this phenomenon, the negative electrode of a lithium-ion battery cell is typically designed to be larger than the positive electrode, resulting in a cell with an overhang (OH) region. The OH region is usually the portion of the negative electrode that extends beyond the positive electrode. During charging and discharging, lithium ions reversibly insert and extract in the OH region. However, its electrochemical response time lags significantly behind that of the active negative electrode region (the area in the negative electrode that directly faces the positive electrode, i.e., the non-OH region in the negative electrode). This causes some active lithium ions to be unusable in subsequent charging and discharging, resulting in a higher-than-expected capacity loss. Currently, existing cell capacity assessment technologies cannot accurately evaluate the capacity loss information of lithium-ion batteries with an overhang region, or the reversible capacity loss information corresponding to the overhang region. Summary of the Invention

[0003] In view of the above problems, this application provides a cell capacity evaluation method, apparatus, storage medium and computer program product, which can accurately determine the capacity loss information corresponding to the cell with the negative electrode OH region and the reversible capacity loss information corresponding to the negative electrode OH region.

[0004] In some embodiments, according to a first aspect of this application, a cell capacity evaluation method is provided, comprising: performing a first discharge test on a first cell and a second cell according to a preset discharge strategy; wherein the first cell is a cell having a negative electrode OH region; the second cell is a reference cell corresponding to the first cell, and the second cell does not have a negative electrode OH region; after the first discharge test, acquiring first discharge capacity information corresponding to the first cell; performing at least one storage process on the first cell and the second cell according to a preset storage strategy, and after each storage process is completed, performing a second discharge test on the first cell and the second cell according to the discharge strategy; after the second discharge test, acquiring second discharge capacity information corresponding to the first cell; and determining capacity loss information corresponding to the first cell and reversible capacity loss information corresponding to the negative electrode OH region based on the first discharge capacity information and the second discharge capacity information.

[0005] In this embodiment, by comparing a first cell with a negative electrode OH region and a second cell without a negative electrode OH region, and performing one or more storage processes and a second discharge test after the first discharge test, the interference of the negative electrode OH region on the cell capacity decay assessment can be effectively eliminated. Based on the discharge capacity information of the first cell and the first and second discharge tests, the capacity loss information corresponding to the first cell and the reversible capacity loss information corresponding to the negative electrode OH region can be accurately determined. This enables the assessment of the thermodynamic capacity loss of the first cell with a negative electrode OH region, and also determines the reversible capacity loss information corresponding to the negative electrode OH region, thus improving the accuracy and reliability of the capacity assessment of the cell with a negative electrode OH region.

[0006] In some embodiments, after the first discharge test, third discharge capacity information corresponding to the second cell is obtained; after the second discharge test, fourth discharge capacity information corresponding to the second cell is obtained; and irreversible capacity loss information corresponding to the negative electrode OH region is determined based on the first discharge capacity information, the second discharge capacity information, the third discharge capacity information, and the fourth discharge capacity information.

[0007] In this embodiment, since the capacity decay of the second cell without a negative electrode OH region is caused only by factors of the cell itself, by comparing and testing the first cell with a negative electrode OH region and the second cell without a negative electrode OH region, the irreversible capacity loss corresponding to the negative electrode OH region can be accurately determined. This achieves accurate assessment of the irreversible capacity loss caused by the negative electrode OH region and improves the accuracy and reliability of capacity assessment for cells with a negative electrode OH region.

[0008] In some embodiments, the discharge strategy includes: performing a first discharge process on the first battery cell and the second battery cell according to a first discharge rate until the voltage of the first battery cell and the second battery cell reaches the discharge cutoff voltage; performing a second discharge process on the first battery cell and the second battery cell at least once according to a second discharge rate until a preset discharge sufficient determination condition is met; wherein the second discharge rate is less than the first discharge rate; and before each second discharge process, the first battery cell and the second battery cell are left to stand for a preset first time.

[0009] In this embodiment, a first discharge process at a higher rate can quickly release most of the battery cell's charge, while a second discharge process at a lower rate can fully release the remaining charge inside the battery cell. Before each second discharge process, both the first and second battery cells are left to stand to avoid residual charge and improve the accuracy of the discharge capacity test. The synergistic effect of the second discharge process and the standing period allows the active lithium in the negative electrode OH region to migrate and be removed fully from the active negative electrode region, achieving the stripping of active lithium from the negative electrode OH region and improving the accuracy and reliability of capacity assessment for battery cells with a negative electrode OH region.

[0010] In some embodiments, the discharge sufficient determination condition includes: after completing all the second discharge processes and resting for a preset second time, the open circuit voltage difference between the first cell and the second cell is less than a preset difference threshold.

[0011] In this embodiment, by setting a condition for sufficient discharge, it is possible to accurately determine whether the cell has reached a fully discharged state. It is possible to determine that the active lithium in the negative electrode OH region has fully migrated to and extracted from the active negative electrode region. The lithium intercalation state in the negative electrode OH region is consistent with that in the active negative electrode region. This can effectively eliminate the interference of the negative electrode OH region on the cell capacity decay assessment and improve the accuracy and reliability of the capacity assessment of cells with a negative electrode OH region.

[0012] In some embodiments, before performing a first discharge test on the first battery cell and the second battery cell, and before performing a second discharge test on the first battery cell and the second battery cell, the method further includes: discharging the first battery cell and the second battery cell based on a preset third discharge rate until the voltage of the first battery cell and the second battery cell reaches the discharge cutoff voltage; and charging the first battery cell and the second battery cell based on a preset charging rate until the voltage of the first battery cell and the second battery cell reaches the charging cutoff voltage.

[0013] In this embodiment, by adding constant current full discharge and full charge preprocessing before performing the first discharge test and the second discharge test, the consistency of the state of charge of the first cell and the second cell can be achieved, avoiding the influence of the difference in the state of charge of the first cell and the second cell on the test results, and improving the accuracy and reliability of capacity assessment for cells with negative electrode OH regions.

[0014] In some embodiments, after performing a first discharge test on the first battery cell and the second battery cell, and after performing a second discharge test on the first battery cell and the second battery cell, the method further includes: performing a power adjustment process on the first battery cell and the second battery cell to make the SOC of the first battery cell and the second battery cell reach a preset SOC.

[0015] In this embodiment, by performing power adjustment processing on the first and second battery cells after the first discharge test and the second discharge test, the SOC of the first and second battery cells can reach the preset SOC, which can achieve the consistency of the state of charge of the first and second battery cells, avoid test data deviation caused by the inconsistency of the state of charge of the first and second battery cells, and improve the accuracy and reliability of battery cell capacity assessment.

[0016] In some embodiments, the first discharge capacity information includes: a first discharge capacity value of the first cell undergoing a first discharge treatment in the first discharge test, and a second discharge capacity value of the first cell undergoing the first discharge test; the second discharge capacity information includes: a third discharge capacity value of the first cell undergoing a first discharge treatment in the second discharge test, and a fourth discharge capacity value of the first cell undergoing the second discharge test.

[0017] In some embodiments, determining the capacity loss information corresponding to the first cell based on the first discharge capacity information and the second discharge capacity information includes: determining the difference between the second discharge capacity value and the fourth discharge capacity value as the capacity loss information.

[0018] In this embodiment, by calculating the difference between the second discharge capacity value and the fourth discharge capacity value, the capacity loss information of the first cell during storage is determined. This enables accurate acquisition of the capacity loss information of the first cell, improving the accuracy and reliability of capacity assessment for cells with a negative electrode OH region.

[0019] In some embodiments, determining the reversible capacity loss information corresponding to the negative electrode OH region based on the first discharge capacity information and the second discharge capacity information includes: determining a first difference between the first discharge capacity value and the third discharge capacity value; determining a second difference between the second discharge capacity value and the fourth discharge capacity value; and determining the difference between the first difference and the second difference as the reversible capacity loss information.

[0020] In this embodiment, by calculating the first difference between the first discharge capacity value and the third discharge capacity value, and the second difference between the second discharge capacity value and the fourth discharge capacity value, the difference between the first difference and the second difference is determined as the reversible capacity loss. This allows for the accurate acquisition of the reversible capacity loss corresponding to the negative electrode OH region, thereby improving the accuracy and reliability of capacity assessment for cells with a negative electrode OH region.

[0021] In some embodiments, the third discharge capacity information includes: a fifth discharge capacity value of the second cell after performing the first discharge test; the fourth discharge capacity information includes: a sixth discharge capacity value of the second cell after performing the second discharge test.

[0022] In some embodiments, determining the irreversible capacity loss information corresponding to the negative electrode OH region based on the first discharge capacity information, the second discharge capacity information, the third discharge capacity information, and the fourth discharge capacity information includes: determining a third difference between the second discharge capacity value and the fourth discharge capacity value; determining a fourth difference between the fifth discharge capacity value and the sixth discharge capacity value; and determining the difference between the third difference and the fourth difference as the irreversible capacity loss information.

[0023] In this embodiment, by calculating the third difference between the second discharge capacity value and the fourth discharge capacity value, and the fourth difference between the fifth discharge capacity value and the sixth discharge capacity value, the difference between the third difference and the fourth difference is determined as irreversible capacity loss information. This can accurately determine the irreversible capacity loss information corresponding to the negative electrode OH region, thereby improving the accuracy and reliability of capacity assessment for cells with a negative electrode OH region.

[0024] In some embodiments, the storage strategy includes: placing the first battery cell and the second battery cell in an environment with a preset first temperature and keeping them at that temperature for a preset third duration.

[0025] In this embodiment, by placing the first cell and the second cell in an environment with a first temperature and keeping them at that temperature for a preset third time, the internal electrochemical state of the first cell and the second cell can be kept sufficiently stable, so that the capacity loss characteristics of the negative electrode OH region can be fully manifested, thereby improving the accuracy and repeatability of the cell capacity loss assessment results.

[0026] In some embodiments, a first curve is constructed based on the capacity loss information and the corresponding storage processing duration to show how the capacity loss information changes with the storage processing duration; and / or, a second curve is constructed based on the reversible capacity loss information and the corresponding storage processing duration to show how the reversible capacity loss information changes with the storage processing duration.

[0027] In this embodiment, by constructing curves showing the changes in capacity loss information of the first cell and reversible capacity loss information corresponding to the negative electrode OH region with storage processing time, the capacity loss information of the first cell under different storage durations and the reversible capacity loss information corresponding to the negative electrode OH region can be determined intuitively and accurately.

[0028] In some embodiments, according to a second aspect of this application, a battery cell capacity evaluation apparatus is provided, comprising: a first testing module, configured to perform a first discharge test on a first battery cell and a second battery cell according to a preset discharge strategy; wherein the first battery cell is a battery cell having a negative electrode OH region; the second battery cell is a reference battery cell corresponding to the first battery cell, and the second battery cell does not have a negative electrode OH region; a first information acquisition module, configured to acquire first discharge capacity information corresponding to the first battery cell after the first discharge test; a second testing module, configured to perform at least one storage process on the first battery cell and the second battery cell according to a preset storage strategy, and, after each storage process is completed, perform a second discharge test on the first battery cell and the second battery cell according to the discharge strategy; a second information acquisition module, configured to acquire second discharge capacity information corresponding to the first battery cell after the second discharge test; and a capacity loss determination module, configured to determine capacity loss information corresponding to the first battery cell and reversible capacity loss information corresponding to the negative electrode OH region based on the first discharge capacity information and the second discharge capacity information.

[0029] In this embodiment, by comparing a first cell with a negative electrode OH region and a second cell without a negative electrode OH region, and performing one or more storage processes and a second discharge test after the first discharge test, the interference of the negative electrode OH region on the cell capacity decay assessment can be effectively eliminated. Based on the discharge capacity information of the first cell and the first and second discharge tests, the capacity loss information corresponding to the first cell and the reversible capacity loss information corresponding to the negative electrode OH region can be accurately determined. This enables the assessment of the thermodynamic capacity loss of the first cell with a negative electrode OH region, and also determines the reversible capacity loss information corresponding to the negative electrode OH region, thus improving the accuracy and reliability of the capacity assessment of the cell with a negative electrode OH region.

[0030] In some embodiments, according to a third aspect of this application, an electronic device is provided, comprising: a memory; and a processor coupled to the memory, the processor being configured to perform the method described above based on instructions stored in the memory.

[0031] In some embodiments, according to a fourth aspect of this application, a computer-readable storage medium is provided that stores computer instructions which are executed by a processor using the method described above.

[0032] In some embodiments, according to a fifth aspect of this application, a computer program product is provided, the computer program product storing computer instructions which are executed by a processor using the method described above.

[0033] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0035] Figure 1 This is a flowchart illustrating some embodiments of the cell capacity evaluation method of this application;

[0036] Figure 2 This is a flowchart illustrating the determination of irreversible capacity loss information in some embodiments of the cell capacity assessment method of this application.

[0037] Figure 3 This is a schematic diagram of the process for calculating capacity loss information in some embodiments of the cell capacity evaluation method of this application;

[0038] Figure 4 This is a flowchart illustrating the calculation of reversible capacity loss information in some embodiments of the cell capacity evaluation method of this application.

[0039] Figure 5 This is a schematic diagram of the process for calculating irreversible capacity loss information in some embodiments of the cell capacity evaluation method of this application;

[0040] Figure 6 This is a schematic diagram of capacity loss information in some embodiments of the cell capacity evaluation method of this application;

[0041] Figure 7 This is a schematic diagram illustrating irreversible capacity loss information in some embodiments of the cell capacity evaluation method of this application;

[0042] Figure 8 This is a schematic diagram of reversible capacity loss information in some embodiments of the cell capacity evaluation method of this application;

[0043] Figure 9A This is a schematic diagram of the first curve showing how capacity loss information changes with storage processing time in some embodiments of the cell capacity evaluation method of this application.

[0044] Figure 9BThis is a schematic diagram of the second curve showing the change of reversible capacity loss information with storage processing time in some embodiments of the cell capacity evaluation method of this application;

[0045] Figure 10A Schematic diagrams of some embodiments of the cell capacity evaluation device of this application;

[0046] Figure 10B Schematic diagrams of modules for some other embodiments of the cell capacity evaluation device of this application;

[0047] Figure 11 This is a schematic diagram of modules for some embodiments of the electronic device of this application. Detailed Implementation

[0048] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0050] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0051] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least some of the embodiments of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0052] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0053] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0054] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0055] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0056] Figure 1 This is a flowchart illustrating some embodiments of the cell capacity evaluation method of this application, such as... Figure 1 As shown, the cell capacity evaluation method includes steps S101 to S105:

[0057] Step S101: Perform a first discharge test on the first battery cell and the second battery cell according to the preset discharge strategy.

[0058] The discharge strategy can be various, involving the discharge of both the first and second battery cells. The first battery cell is one with a negative electrode (OH) region, and can be a lithium-ion battery cell, etc. The negative electrode (OH) region can be an overhanging area where the negative electrode plate is larger than the positive electrode plate in the width and / or length directions, extending beyond the edge of the positive electrode plate. The second battery cell is a reference cell corresponding to the first battery cell, but does not have a negative electrode (OH) region. The second battery cell can also be a lithium-ion battery cell, etc. The second battery cell uses the same positive electrode material, negative electrode material, and manufacturing process as the first battery cell; the only difference between the first and second battery cells is the presence or absence of a negative electrode (OH) region.

[0059] The first and second cells can be in the form of two electrodes. The positive and negative electrode materials of both cells can be various materials, with no particular limitation on their specific applications. For example, the positive electrode materials of both cells can be lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium cobalt oxide, lithium-rich manganese-based oxide, etc., while the negative electrode materials can be graphite, silicon, etc. The proportion of the OH region in the negative electrode of the first cell to the cathode area can be 0.1%-10%, etc.; the second cell is a zero-OH cell, with the negative electrode sheet having the same size as the positive electrode sheet.

[0060] Step S102: After the first discharge test, obtain the first discharge capacity information corresponding to the first cell.

[0061] The first discharge capacity information is the discharge capacity data of the first cell obtained after performing a first discharge test on the first cell according to the discharge strategy; various existing methods can be used to obtain the first discharge capacity information corresponding to the first cell.

[0062] Step S103: Perform at least one storage process on the first battery cell and the second battery cell according to the preset storage strategy, and after each storage process is completed, perform a second discharge test on the first battery cell and the second battery cell according to the discharge strategy.

[0063] The storage strategy can be varied for storing the first and second battery cells. One or more storage processes are performed on the first and second battery cells, and after each storage process, a second discharge test is performed on the first and second battery cells according to a discharge strategy. The storage process and the second discharge test can be performed repeatedly on the first and second battery cells.

[0064] Step S104: After the second discharge test, obtain the second discharge capacity information corresponding to the first cell.

[0065] The second discharge capacity information is the discharge capacity data obtained after the first cell has undergone preset storage processing and a second discharge test has been performed according to the discharge strategy. Various existing methods can be used to obtain the second discharge capacity information corresponding to the first cell. In the case of multiple storage processes and second discharge tests, the second discharge capacity information corresponding to the first cell can be obtained after each execution of the second discharge test.

[0066] Step S105: Based on the first discharge capacity information and the second discharge capacity information, determine the capacity loss information corresponding to the first cell and the reversible capacity loss information corresponding to the negative electrode OH region.

[0067] The capacity loss information corresponding to the first cell can be the actual thermodynamic capacity loss information of the first cell, etc. The reversible capacity loss information corresponding to the negative electrode OH region can be the reversible capacity loss information recovered through charging and discharging or resting, and is the reversible capacity loss information caused by the negative electrode OH region.

[0068] Under the condition of performing multiple storage processes and a second discharge test, the second discharge capacity information corresponding to each storage process and the second discharge test is obtained; based on the first discharge capacity information and the second discharge capacity information corresponding to each storage process and the second discharge test, multiple capacity loss information corresponding to the first cell and multiple reversible capacity loss information corresponding to the negative electrode OH region can be determined.

[0069] By comparing a first cell with a negative electrode OH region with a second cell without a negative electrode OH region, and performing one or more storage processes and a second discharge test after the first discharge test, the interference of the negative electrode OH region on the cell capacity decay assessment can be effectively eliminated. Based on the discharge capacity information of the first cell and the first and second discharge tests, the capacity loss information corresponding to the first cell and the reversible capacity loss information corresponding to the negative electrode OH region can be accurately determined. This allows for the assessment of the thermodynamic capacity loss of the first cell with a negative electrode OH region, and the determination of the reversible capacity loss information corresponding to the negative electrode OH region, thus improving the accuracy and reliability of the capacity assessment of the cell with a negative electrode OH region.

[0070] Figure 2 This is a flowchart illustrating the determination of irreversible capacity loss information in some embodiments of the cell capacity assessment method of this application, such as... Figure 2 As shown, the method for determining irreversible capacity loss information includes steps S201 to S203:

[0071] Step S201: After the first discharge test, obtain the third discharge capacity information corresponding to the second cell.

[0072] The third discharge capacity information is the discharge capacity data of the second cell obtained after the first discharge test is performed on the second cell according to the discharge strategy; various existing methods can be used to obtain the third discharge capacity information corresponding to the second cell.

[0073] Step S202: After the second discharge test, obtain the fourth discharge capacity information corresponding to the second cell.

[0074] The fourth discharge capacity information is the discharge capacity data obtained after the second cell has completed the preset storage processing and the second discharge test has been performed according to the discharge strategy; various existing methods can be used to obtain the fourth discharge capacity information corresponding to the second cell.

[0075] Step S203: Based on the first discharge capacity information, the second discharge capacity information, the third discharge capacity information, and the fourth discharge capacity information, determine the irreversible capacity loss information corresponding to the negative electrode OH region.

[0076] The irreversible capacity loss information corresponding to the negative electrode OH region refers to the irreversible capacity loss information that cannot be recovered through charging, discharging, or resting, i.e., the irreversible capacity loss information brought about by the negative electrode OH region.

[0077] In the case of performing multiple storage processes and a second discharge test, the third discharge capacity information and the fourth discharge capacity information corresponding to each storage process and the second discharge test are obtained; based on the first discharge capacity information, the second discharge capacity information, and the third discharge capacity information and the fourth discharge capacity information corresponding to each storage process and the second discharge test, multiple irreversible capacity loss information corresponding to the negative electrode OH region can be determined.

[0078] Since the capacity decay of the second cell without a negative electrode OH region is caused solely by factors within the cell itself, by comparing and testing the first cell with a negative electrode OH region with the second cell without a negative electrode OH region, the irreversible capacity loss corresponding to the negative electrode OH region can be accurately determined. This enables a precise assessment of the irreversible capacity loss caused by the negative electrode OH region, improving the accuracy and reliability of capacity assessment for cells with a negative electrode OH region.

[0079] In some embodiments, the discharge strategy can be a variety of strategies. For example, the discharge strategy includes: performing a first discharge process on the first battery cell and the second battery cell according to a first discharge rate until the voltage of the first battery cell and the second battery cell reaches the discharge cutoff voltage; performing a second discharge process on the first battery cell and the second battery cell at least once according to a second discharge rate until a preset discharge sufficient determination condition is met; and placing the first battery cell and the second battery cell in a static state for a preset first time before each second discharge process.

[0080] The first and second discharge rates can be various ratios, with the second discharge rate being lower than the first. The first discharge duration can be 30 minutes, 60 minutes, etc. The number of second discharge cycles can be 10, 20, etc. The discharge cutoff voltage is the critical voltage at which the first and second cells stop discharging when they reach a specified lower voltage limit during the discharge process.

[0081] A first discharge at a higher rate can quickly release most of the battery cell's charge, while a second discharge at a lower rate can fully release any remaining charge within the cell. Allowing both cells to stand before each second discharge process prevents residual charge and improves the accuracy of discharge capacity testing. The combined effect of the second discharge and standing allows active lithium in the negative electrode OH region to migrate and be removed, effectively stripping the active lithium from the OH region and enhancing the accuracy and reliability of capacity assessment for cells with a negative electrode OH region.

[0082] In some embodiments, the discharge completion determination condition can be multiple conditions. For example, the discharge completion determination condition includes: after completing all the second discharge processes and resting for a preset second time, the open-circuit voltage difference between the first cell and the second cell is less than a preset difference threshold.

[0083] The difference threshold can be set, for example, to 2mV; when the difference between the open-circuit voltages of the first cell and the second cell is less than the difference threshold, it can be determined that the open-circuit voltages of the first cell and the second cell are the same. The second duration can be set, for example, to 30 minutes, 60 minutes, etc.

[0084] By setting sufficient discharge criteria, it is possible to accurately determine whether the cell has reached a fully discharged state. This ensures that the active lithium in the negative electrode OH region has fully migrated to and extracted from the active negative electrode region, and that the lithium intercalation state in the negative electrode OH region is consistent with that in the active negative electrode region. This effectively eliminates the interference of the negative electrode OH region on the cell capacity decay assessment, and improves the accuracy and reliability of capacity assessment for cells with a negative electrode OH region.

[0085] In some embodiments, the storage strategy can be multiple strategies. For example, the storage strategy includes: placing the first battery cell and the second battery cell in an environment with a preset first temperature and maintaining the temperature for a preset third duration. The first temperature can be a variety of temperatures, for example, -25℃ to 70℃; the third duration can be 3 days, 7 days, 14 days, etc.

[0086] By placing the first and second cells in an environment with a first temperature and maintaining the temperature for a preset third time, the internal electrochemical state of the first and second cells can be fully stabilized, allowing the capacity loss characteristics of the negative electrode OH region to be fully manifested, thus improving the accuracy and repeatability of the cell capacity loss assessment results.

[0087] In some embodiments, before performing the first discharge test and the second discharge test, the first and second battery cells are discharged based on a preset third discharge rate until their voltages reach the discharge cutoff voltage; then, the first and second battery cells are charged based on a preset charging rate until their voltages reach the charging cutoff voltage. The charging cutoff voltage is the critical voltage at which charging stops when a specified upper voltage limit is reached during battery charging. The third discharge rate and the charging rate can be multiple rates.

[0088] By adding constant current full discharge and full charge preprocessing before the first discharge test and the second discharge test, the consistency of the state of charge of the first cell and the second cell can be achieved, avoiding the influence of the difference in the state of charge of the first cell and the second cell on the test results, and improving the accuracy and reliability of capacity assessment for cells with negative electrode OH region.

[0089] In some embodiments, after performing a first discharge test on the first battery cell and the second battery cell, and after performing a second discharge test on the first battery cell and the second battery cell, the first battery cell and the second battery cell are subjected to a power adjustment process to bring their State of Charge (SOC) to a preset SOC. The preset SOC can be set, for example, to 0%-100% SOC.

[0090] By performing power adjustment processing on the first and second battery cells after the first and second discharge tests, the state of charge (SOC) of the first and second battery cells can reach the preset SOC. This ensures the consistency of the state of charge of the first and second battery cells, avoids test data deviations caused by inconsistencies in the state of charge of the first and second battery cells, and improves the accuracy and reliability of battery cell capacity assessment.

[0091] In some embodiments, the first discharge capacity information includes: the first discharge capacity value of the first discharge treatment in the first discharge test of the first cell, and the second discharge capacity value of the first cell in the first discharge test.

[0092] The second discharge capacity information includes: the third discharge capacity value of the first discharge treatment during the second discharge test of the first cell, and the fourth discharge capacity value of the first cell during the second discharge test.

[0093] The third discharge capacity information includes the fifth discharge capacity value of the second cell during the first discharge test. The fourth discharge capacity information includes the sixth discharge capacity value of the second cell during the second discharge test.

[0094] In some embodiments, a first battery cell and a second battery cell are prepared. The first battery cell is a lithium battery cell with a negative electrode OH region, and the second battery cell is a lithium battery reference cell that matches the first battery cell, and the second battery cell has no negative electrode OH region. There are no special limitations on the positive and negative electrode materials of the first and second battery cells. The negative electrode area of ​​the first battery cell is larger than the positive electrode area. When the positive and negative electrodes are assembled into a battery cell, they are centered and aligned on the top, bottom, left, and right sides. The negative electrode edge extends beyond the positive electrode edge to form a negative electrode OH region, and the proportion of the negative electrode OH region to the cathode area is 0.1%-10%, etc. The negative electrode area of ​​the second battery cell is equal to the positive electrode area. When the positive and negative electrodes are assembled into a battery cell, they are centered and aligned on the top, bottom, left, and right sides. The negative electrode edge is completely aligned with the positive electrode edge, and no negative electrode OH region is formed.

[0095] The newly prepared first and second battery cells can be activated. For example, the first and second battery cells can be placed in an oven for heat treatment at a temperature of 20℃-30℃ for 1 hour, 2 hours, or 3 hours. After the heat treatment, the first and second battery cells are connected to a charge / discharge machine for discharge-charge cycles to activate the cells. The number of discharge-charge cycles can be 2 or 3 times.

[0096] Before performing the first discharge test on the first and second battery cells, the first and second battery cells are discharged at a preset third discharge rate until their voltages reach the discharge cutoff voltage, i.e., a constant current full discharge is performed on the first and second battery cells. For example, the third discharge rate is 0.33C + 0.04C, and the time interval between each discharge step is 15 minutes. Various existing methods can be used to discharge the first and second battery cells at the preset third discharge rate.

[0097] The first and second battery cells are charged based on a preset charging rate until their voltages reach the charging cutoff voltage, i.e., a constant current full charge is performed on both cells. The charging rate can include a constant current full charge rate and a cutoff current rate. For example, the charging rate could include a constant current full charge rate of 0.33C and a cutoff rate of 0.05C. Various existing methods can be used to charge the first and second battery cells based on this charging rate.

[0098] According to a preset discharge strategy, a first discharge test is performed on the first and second battery cells. This first discharge test can be a constant current full discharge. The specific details of the first discharge test are as follows:

[0099] According to the first discharge rate, the first and second battery cells undergo a first discharge process until their voltages reach the discharge cutoff voltage, i.e., a constant current full discharge is performed on the first and second battery cells. For example, the first discharge rate can be 0.33C + 0.04C, etc. The first discharge rate and the third discharge rate can be the same or different.

[0100] According to the second discharge rate (e.g., the second discharge rate is 0.01C-0.04C, etc.), the first cell and the second cell are subjected to one or more second discharge processes until the preset discharge full determination conditions are met; wherein, before each second discharge process, the first cell and the second cell are left to stand for a preset first time, the first time being 1 hour, etc.

[0101] The first set time for the static setting and the second discharge process can be repeated 2-20 times, and it can be determined whether the preset discharge condition is met. If the discharge condition is met, it is determined that the active lithium in the negative electrode OH region has been completely removed.

[0102] The condition for determining sufficient discharge is as follows: after completing all second discharge processes and being left to stand for a preset second time, the difference between the open-circuit voltages of the first cell and the second cell is less than a preset difference threshold. The second time can be 1 hour, etc.; the difference threshold can be 2mV, etc. If the difference between the open-circuit voltages of the first cell and the second cell is less than the preset difference threshold, then the open-circuit voltages of the first cell and the second cell can be considered to be the same.

[0103] After performing the first discharge test on the first and second cells, the first and second cells are subjected to power adjustment treatment to make the SOC of the first and second cells reach the preset SOC, which can be 0%-100% SOC.

[0104] After the first discharge test, the first discharge capacity information corresponding to the first cell and the third discharge capacity information corresponding to the second cell are obtained.

[0105] The first discharge capacity information includes: the first discharge capacity value D2 during the first discharge treatment of the first cell in the first discharge test, and the second discharge capacity value D2' during the first discharge test of the first cell. The third discharge capacity information includes: the fifth discharge capacity value D2' during the first discharge test of the second cell.

[0106] After the first discharge test, the first cell and the second cell are subjected to one or more storage processes according to a preset storage strategy. After each storage process is completed, the first cell and the second cell are subjected to a second discharge test according to the discharge strategy. The storage process and the second discharge test can be repeated multiple times.

[0107] The storage strategy involves placing the first and second battery cells in an environment with a preset first temperature and maintaining this temperature for a preset third duration. The first temperature can be -25°C to 70°C, and the third duration can be 7 days, 10 days, etc. For example, after the first discharge test, according to the preset storage strategy, the first and second battery cells are subjected to one or more open-circuit storage operations. Open-circuit storage involves disconnecting the charging / discharging machine from the first and second battery cells, placing the first and second battery cells in an oven, setting the oven temperature to 50°C, and storing them for 7 days.

[0108] After each storage process is completed, a second discharge test can be performed on the first and second cells according to the discharge strategy. The second discharge test is as follows:

[0109] Set the oven temperature to 25℃ and keep it warm for 2 hours. Connect the first and second battery cells to the charger / discharger.

[0110] Before performing the second discharge test on the first and second battery cells, the first and second battery cells are discharged based on a preset third discharge rate until their voltages reach the discharge cutoff voltage, i.e., a constant current full discharge is performed on the first and second battery cells. For example, the third discharge rate is 0.33C + 0.04C, and the time interval is 15 minutes.

[0111] The first and second battery cells are charged based on a preset charging rate until their voltages reach the charging cutoff voltage, i.e., a constant current full charge is performed on the first and second battery cells. For example, the charging rate may include a constant current charging rate and a cutoff current rate. Various existing methods can be used to charge the first and second battery cells based on the charging rate until their voltages reach the charging cutoff voltage.

[0112] According to a preset discharge strategy, a second discharge test is performed on the first and second battery cells. The second discharge test is a constant current full discharge. The second discharge test can be as follows:

[0113] According to the first discharge rate, the first and second battery cells undergo a first discharge process until their voltages reach the discharge cutoff voltage, i.e., a constant current full discharge is performed on the first and second battery cells. For example, the first discharge rate is 0.33C + 0.04C, etc. The first discharge rate and the third discharge rate can be the same or different.

[0114] According to the second discharge rate (e.g., the second discharge rate is 0.01C-0.04C, etc.), the first cell and the second cell are subjected to one or more second discharge processes until the preset discharge full determination conditions are met; wherein, before each second discharge process, the first cell and the second cell are left to stand for a preset first time, the first time being 1 hour, etc.

[0115] The first set time and the second discharge process can be repeated 2-20 times to determine whether the preset discharge conditions are met. If the discharge conditions are met, it is determined that the active lithium in the negative electrode OH region has been completely removed.

[0116] The condition for determining sufficient discharge is as follows: after completing all second discharge processes and being left to stand for a preset second time, the difference between the open-circuit voltages of the first cell and the second cell is less than a preset difference threshold. The second time can be 1 hour, etc.; the difference threshold can be 2mV, etc. If the difference between the open-circuit voltages of the first cell and the second cell is less than the preset difference threshold, then the open-circuit voltages of the first cell and the second cell can be considered to be the same.

[0117] If the discharge condition is met, it means that the discharge is sufficient. If the discharge condition is not met, the number of second discharge processes performed on the first and second cells is increased until the discharge condition is met.

[0118] After performing a second discharge test on the first and second battery cells, the first and second battery cells are subjected to power adjustment treatment to bring their SOC to a preset SOC, which can be 0%-100% SOC.

[0119] After performing a second discharge test on the first and second cells, due to the sufficient discharge of both cells, the active lithium in the negative electrode OH region can migrate fully from the negative electrode OH region to the active anode region. Following the second discharge test, second discharge capacity information corresponding to the first cell is obtained; following the second discharge test, fourth discharge capacity information corresponding to the second cell is obtained.

[0120] The second discharge capacity information includes: the third discharge capacity value D(2+2n)' of the first discharge treatment during the second discharge test of the first cell, and the fourth discharge capacity value D(2+2n)' of the first cell during the second discharge test, where n is the number of storage treatments performed on the first and second cells and the number of second discharge tests. The fourth discharge capacity information includes: the sixth discharge capacity value OD(2+2n)' of the second cell during the second discharge test.

[0121] For example, performing one storage process and a second discharge test on the first and second battery cells, n=1, the second discharge capacity information includes: the third discharge capacity value D(4), the fourth discharge capacity value D(4)'; the fourth discharge capacity information includes: the sixth discharge capacity value OD(4)'. Performing two storage processes and a second discharge test on the first and second battery cells, n=2, the second discharge capacity information includes: the third discharge capacity value D(6), the fourth discharge capacity value D(6)'; the fourth discharge capacity information includes: the sixth discharge capacity value OD(6)'.

[0122] Figure 3 This is a flowchart illustrating the calculation of capacity loss information in some embodiments of the cell capacity evaluation method of this application, such as... Figure 3 As shown, the method for calculating capacity loss information includes step S301:

[0123] Step S301: The difference between the second discharge capacity value and the fourth discharge capacity value is determined as capacity loss information.

[0124] During the first and second discharge tests, the active lithium in the negative electrode OH region of both the first and second cells can fully migrate to the active region and be fully stripped from the negative electrode. This ensures that the obtained second discharge capacity value D2' and fourth discharge capacity value D(2+2n)' represent the true thermodynamic capacity, eliminating the influence of active lithium in the negative electrode OH region. After the first and second discharge tests, the negative electrode OH region of both the first and second cells shows almost no active lithium, and its lithium intercalation state is consistent with that of the active negative electrode region. This avoids OH lithium deposition caused by a higher lithium intercalation state in the negative electrode OH region compared to the active negative electrode region.

[0125] The difference between the second discharge capacity value D2' and the fourth discharge capacity value D(2+2n)' is determined as the capacity loss information, which is D2'-D(2+2n)'; the capacity loss information is the actual thermodynamic capacity loss information corresponding to the first cell.

[0126] For example, if the first and second cells are subjected to one storage process and a second discharge test, n=1, the capacity loss information is D2'-D(4)'. If the first and second cells are subjected to two storage processes and a second discharge test, n=2, the capacity loss information is D2'-D(6)'.

[0127] By calculating the difference between the second and fourth discharge capacity values, the capacity loss information of the first cell during storage can be determined. This allows for accurate acquisition of the capacity loss information of the first cell, improving the accuracy and reliability of capacity assessment for cells with a negative electrode OH region.

[0128] Figure 4This is a flowchart illustrating the calculation of reversible capacity loss information in some embodiments of the cell capacity evaluation method of this application, such as... Figure 4 As shown, the method for calculating reversible capacity loss information includes steps S401 to S403:

[0129] Step S401: Determine the first difference between the first discharge capacity value and the third discharge capacity value.

[0130] Step S402: Determine the second difference between the second discharge capacity value and the fourth discharge capacity value.

[0131] Step S403: The difference between the first difference and the second difference is determined as the reversible capacity loss information.

[0132] In some embodiments, the capacity loss information of the first cell is D2'-D(2+2n)', and the thermodynamic capacity loss including the reversible capacity loss of the negative electrode OH region is D2-D(2+2n). A first difference between the first discharge capacity value D2 and the third discharge capacity value D(2+2n) is determined, where the first difference is D2-D(2+2n); a second difference between the second discharge capacity value D2' and the fourth discharge capacity value D(2+2n)' is determined, where the second difference is D2'-D(2+2n)'; the difference between the first and second differences is determined as the reversible capacity loss information corresponding to the negative electrode OH region, where the reversible capacity loss information is {D2-D(2+2n)}-{D2'-D(2+2n)'}.

[0133] For example, after performing one storage process and a second discharge test on the first and second cells, n=1, the reversible capacity loss information corresponding to the negative electrode OH region is {D2-D(4)}-{D2'-D(4)'}. After performing two storage processes and a second discharge test on the first and second cells, n=2, the reversible capacity loss information corresponding to the negative electrode OH region is {D2-D(6)}-{D2'-D(6)'}.

[0134] By calculating the first difference between the first discharge capacity value and the third discharge capacity value, and the second difference between the second discharge capacity value and the fourth discharge capacity value, the difference between the first difference and the second difference is determined as the reversible capacity loss. This allows for the accurate acquisition of the reversible capacity loss corresponding to the negative electrode OH region, thus improving the accuracy and reliability of capacity assessment for cells with a negative electrode OH region.

[0135] Figure 5 This is a flowchart illustrating the calculation of irreversible capacity loss information in some embodiments of the cell capacity evaluation method of this application, such as... Figure 5 As shown, the method for calculating irreversible capacity loss information includes steps S501 to S503:

[0136] Step S501: Determine the third difference between the second discharge capacity value and the fourth discharge capacity value.

[0137] Step S502: Determine the fourth difference between the fifth discharge capacity value and the sixth discharge capacity value.

[0138] Step S503: The difference between the third difference and the fourth difference is determined as irreversible capacity loss information.

[0139] In some embodiments, the capacity loss information of the first cell is D2'-D(2+2n)'. The capacity loss information of the second cell is OD2'-OD(2+2n)', which is the true thermodynamic capacity loss information of the second cell. The capacity loss information of the first cell includes the irreversible capacity loss corresponding to the negative electrode OH region, that is, the irreversible capacity loss caused by the negative electrode OH region.

[0140] Determine the third difference between the second discharge capacity value D2' and the fourth discharge capacity value D(2+2n)', where the third difference is D2'-D(2+2n)'; determine the fourth difference between the fifth discharge capacity value 0D2' and the sixth discharge capacity value 0D(2+2n)', where the fourth difference is 0D2'-0D(2+2n)'; and determine the difference between the third and fourth differences as irreversible capacity loss information, where the irreversible capacity loss information is {D2'-D(2+2n)'}-{0D2'-0D(2+2n)'}.

[0141] For example, if the first and second cells undergo one storage process and a second discharge test, with n=1, the irreversible capacity loss information corresponding to the negative electrode OH region is {D2'-D(4)'}-{0D2'-0D(4)'}. If the first and second cells undergo two storage processes and a second discharge test, with n=2, the irreversible capacity loss information corresponding to the negative electrode OH region is {D2'-D(6)'}-{0D2'-0D(6)'}.

[0142] By calculating the third difference between the second and fourth discharge capacity values, and the fourth difference between the fifth and sixth discharge capacity values, the difference between the third and fourth differences is determined as irreversible capacity loss information. This allows for the accurate acquisition of irreversible capacity loss information corresponding to the negative electrode OH region, thus improving the accuracy and reliability of capacity assessment for cells with a negative electrode OH region.

[0143] In some embodiments, the first and second cells can be stacked cells with a capacity of 120mAh. The first cell has a negative electrode (OH) region, and the second cell is a reference cell corresponding to the first cell but does not have a negative electrode (OH) region. After performing a first discharge test on the first and second cells, multiple storage processes are performed on them. After each storage process, a second discharge test is performed on the first and second cells. The storage process temperature is 60°C, and each storage process lasts for 7 days.

[0144] like Figure 6 As shown, point 61 represents the capacity loss information of the first battery cell calculated after one storage process and a second discharge test on the first and second battery cells, which is the capacity loss rate; point 62 represents the capacity loss information of the second battery cell calculated after one storage process and a second discharge test on the first and second battery cells, which is the capacity loss rate; point 63 represents the capacity loss information of the first battery cell calculated after two storage processes and a second discharge test on the first and second battery cells, which is the capacity loss rate; point 64 represents the capacity loss information of the second battery cell calculated after two storage processes and a second discharge test on the first and second battery cells, which is the capacity loss rate; as shown... Figure 6 As shown, the capacity loss rate of the first cell is slightly higher than that of the second cell.

[0145] like Figure 7 As shown, point 71 represents the irreversible capacity loss information corresponding to the negative electrode OH region of the first battery cell, calculated after performing one storage process and a second discharge test on the first and second battery cells; point 72 represents the irreversible capacity loss information corresponding to the negative electrode OH region of the first battery cell, calculated after performing two storage processes and a second discharge test on the first and second battery cells. Figure 7 As shown, the irreversible capacity loss information is the irreversible capacity loss rate. On day 15, the irreversible capacity loss rate corresponding to the negative electrode OH region of the first cell is approximately 0.13%.

[0146] like Figure 8 As shown, point 81 represents the reversible capacity loss information corresponding to the negative electrode OH region of the first battery cell, calculated after performing one storage process and a second discharge test on the first and second battery cells; point 82 represents the reversible capacity loss information corresponding to the negative electrode OH region of the first battery cell, calculated after performing two storage processes and a second discharge test on the first and second battery cells. Figure 8 As shown, the reversible capacity loss information is the reversible capacity loss rate. On the 15th day, the reversible capacity loss rate corresponding to the negative electrode OH region of the first cell no longer increases, indicating that the reversible capacity loss caused by the negative electrode OH region has reached equilibrium within 7 days.

[0147] In some embodiments, a first curve is constructed based on one or more capacity loss information and the corresponding storage processing duration to show how the capacity loss information of the first cell changes with the storage processing duration; and / or, a second curve is constructed based on one or more reversible capacity loss information and the corresponding storage processing duration to show how the reversible capacity loss information of the first cell changes with the storage processing duration.

[0148] For example, such as Figure 9A As shown, the first curve 91 illustrates how the capacity loss information of the first battery cell changes with the storage processing time. Figure 9B As shown, the second curve 92 illustrates how the reversible capacity loss information of the first battery cell changes with the storage processing time.

[0149] In some embodiments, the first cell and the second cell are subjected to three storage processes and a second discharge test. Based on the three capacity loss information (true thermodynamic capacity loss) of the first cell and the corresponding duration of the three storage processes, a first curve is constructed using various existing curve fitting methods to show the change of the capacity loss information of the first cell with the duration of the storage processes.

[0150] Three storage processes and a second discharge test were performed on the first and second cells to obtain three reversible capacity loss information corresponding to the negative electrode OH region and the corresponding storage process duration. Based on the three reversible capacity loss information and the corresponding storage process duration, a second curve of the reversible capacity loss information corresponding to the negative electrode OH region as a function of storage process duration can be constructed using various curve fitting methods.

[0151] By constructing curves showing the changes in capacity loss information of the first cell and the reversible capacity loss information corresponding to the negative electrode OH region with storage processing time, it is possible to intuitively and accurately determine the capacity loss information of the first cell under different storage durations and the reversible capacity loss information corresponding to the negative electrode OH region.

[0152] In some embodiments, such as Figure 10A As shown, this application provides a cell capacity evaluation device, including a first test module 1001, a first information acquisition module 1002, a second test module 1003, a second information acquisition module 1004, and a capacity loss determination module 1005.

[0153] The first test module 1001 performs a first discharge test on the first battery cell and the second battery cell according to a preset discharge strategy; wherein the first battery cell is a battery cell with a negative electrode OH region; the second battery cell is a reference battery cell corresponding to the first battery cell, and the second battery cell does not have a negative electrode OH region.

[0154] After the first discharge test, the first information acquisition module 1002 acquires the first discharge capacity information corresponding to the first battery cell. The second test module 1003 performs at least one storage process on the first battery cell and the second battery cell according to a preset storage strategy. After each storage process is completed, the second test module 1003 performs a second discharge test on the first battery cell and the second battery cell according to the discharge strategy.

[0155] After the second discharge test, the second information acquisition module 1004 acquires the second discharge capacity information corresponding to the first cell; the capacity loss determination module 1005 determines the capacity loss information corresponding to the first cell and the reversible capacity loss information corresponding to the negative electrode OH region based on the first discharge capacity information and the second discharge capacity information.

[0156] In some embodiments, after the first discharge test, the first information acquisition module 1002 acquires third discharge capacity information corresponding to the second cell. After the second discharge test, the second information acquisition module 1004 acquires fourth discharge capacity information corresponding to the second cell. The capacity loss determination module 1005 determines the irreversible capacity loss information corresponding to the negative electrode OH region based on the first discharge capacity information, the second discharge capacity information, the third discharge capacity information, and the fourth discharge capacity information.

[0157] In some embodiments, the first discharge capacity information includes: a first discharge capacity value of the first discharge treatment during the first discharge test of the first cell, and a second discharge capacity value of the first cell during the first discharge test. The second discharge capacity information includes: a third discharge capacity value of the first discharge treatment during the second discharge test of the first cell, and a fourth discharge capacity value of the first cell during the second discharge test.

[0158] The capacity loss determination module 1005 determines the difference between the second discharge capacity value and the fourth discharge capacity value as capacity loss information. The capacity loss determination module 1005 determines the first difference between the first discharge capacity value and the third discharge capacity value, and determines the second difference between the second discharge capacity value and the fourth discharge capacity value; the capacity loss determination module 1005 determines the difference between the first difference and the second difference as reversible capacity loss information.

[0159] The third discharge capacity information includes: the fifth discharge capacity value of the second cell during the first discharge test; the fourth discharge capacity information includes: the sixth discharge capacity value of the second cell during the second discharge test. The capacity loss determination module 1005 determines the third difference between the second discharge capacity value and the fourth discharge capacity value, and determines the fourth difference between the fifth discharge capacity value and the sixth discharge capacity value; the capacity loss determination module 1005 determines the difference between the third difference and the fourth difference as irreversible capacity loss information.

[0160] The capacity loss determination module 1005 constructs a first curve of capacity loss information changing with storage processing time based on capacity loss information and the corresponding storage processing time; and / or, the capacity loss determination module 1005 constructs a second curve of reversible capacity loss information changing with storage processing time based on reversible capacity loss information and the corresponding storage processing time.

[0161] In some embodiments, this application provides another cell capacity evaluation device, which, in addition to including a first test module 1001, a first information acquisition module 1002, a second test module 1003, a second information acquisition module 1004, and a capacity loss determination module 1005, also includes a third test module 1006.

[0162] Before performing the first discharge test on the first battery cell and the second battery cell, and before performing the second discharge test on the first battery cell and the second battery cell, the third test module 1006 discharges the first battery cell and the second battery cell based on a preset third discharge rate until the voltage of the first battery cell and the second battery cell reaches the discharge cutoff voltage; the third test module 1006 charges the first battery cell and the second battery cell based on a preset charging rate until the voltage of the first battery cell and the second battery cell reaches the charging cutoff voltage.

[0163] After performing a first discharge test on the first battery cell and the second battery cell, and after performing a second discharge test on the first battery cell and the second battery cell, the third test module 1006 performs power adjustment processing on the first battery cell and the second battery cell to make the SOC of the first battery cell and the second battery cell reach the preset SOC.

[0164] Figure 11 The diagram below shows a module schematic of some embodiments of an electronic device according to this application. The electronic device may include a memory 1101, a processor 1102, a communication interface 1103, and a bus 1104. The memory 1101 is used to store instructions, and the processor 1102 is coupled to the memory 1101. The processor 1102 is configured to execute the above-described cell capacity evaluation method based on the instructions stored in the memory 1101.

[0165] The memory 1101 can be a high-speed RAM, non-volatile memory, or a memory array. The memory 1101 may also be divided into blocks, and these blocks can be combined into virtual volumes according to certain rules. The processor 1102 can be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the cell capacity evaluation method of this application.

[0166] In some embodiments, this application provides a computer-readable storage medium storing computer instructions that are executed by a processor using the cell capacity evaluation method as described in any of the above embodiments.

[0167] Computer-readable storage media may take the form of any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may, for example, include, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples (not an exhaustive list) of readable storage media may include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0168] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0169] Embodiments of this application may also be computer program products, which include computer program instructions that, when executed by a processor, cause the processor to perform the steps in the cell capacity evaluation methods according to various embodiments of this application described in the "Exemplary Methods" section of this specification.

[0170] The steps of the method of this application are not limited to the order specifically described above, unless otherwise specifically stated. Furthermore, in some embodiments, this application may also be implemented as a program recorded on a recording medium, the program including machine-readable instructions for implementing the method according to this application. Therefore, this application also covers recording media storing programs for performing the method according to this application.

[0171] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments claimed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for evaluating the capacity of a battery cell, characterized in that, include: According to a preset discharge strategy, a first discharge test is performed on the first cell and the second cell; wherein, the first cell is a cell with a negative electrode OH region; the second cell is a reference cell corresponding to the first cell, and the second cell does not have a negative electrode OH region; After the first discharge test, the first discharge capacity information corresponding to the first cell is obtained; According to a preset storage strategy, at least one storage process is performed on the first battery cell and the second battery cell, and after each storage process is completed, a second discharge test is performed on the first battery cell and the second battery cell according to the discharge strategy. After the second discharge test, the second discharge capacity information corresponding to the first cell is obtained; Based on the first discharge capacity information and the second discharge capacity information, determine the capacity loss information corresponding to the first cell and the reversible capacity loss information corresponding to the negative electrode OH region.

2. The method as described in claim 1, characterized in that, Also includes: After the first discharge test, the third discharge capacity information corresponding to the second cell is obtained; After the second discharge test, the fourth discharge capacity information corresponding to the second cell is obtained; Based on the first discharge capacity information, the second discharge capacity information, the third discharge capacity information, and the fourth discharge capacity information, the irreversible capacity loss information corresponding to the negative electrode OH region is determined.

3. The method as described in claim 2, characterized in that, The discharge strategy includes: According to the first discharge rate, the first cell and the second cell are subjected to a first discharge process until the voltage of the first cell and the second cell reaches the discharge cutoff voltage. According to the second discharge rate, the first cell and the second cell are subjected to at least one second discharge process until the preset discharge full determination condition is met; Wherein, the second discharge rate is less than the first discharge rate; before each second discharge process, the first battery cell and the second battery cell are left to stand for a preset first time.

4. The method as described in claim 3, characterized in that, The conditions for determining sufficient discharge include: after completing all the second discharge processes and resting for a preset second time, the difference between the open-circuit voltages of the first cell and the second cell is less than a preset difference threshold.

5. The method as described in claim 3, characterized in that, Before performing a first discharge test on the first battery cell and the second battery cell, and before performing a second discharge test on the first battery cell and the second battery cell, the method further includes: The first cell and the second cell are discharged based on a preset third discharge rate until the voltage of the first cell and the second cell reaches the discharge cutoff voltage. The first and second battery cells are charged according to a preset charging rate until their voltages reach the charging cutoff voltage.

6. The method as described in claim 3, characterized in that, After performing a first discharge test on the first battery cell and the second battery cell, and after performing a second discharge test on the first battery cell and the second battery cell, the method further includes: The first and second battery cells are subjected to power adjustment processing to make their State of Charge (SOC) reach a preset value.

7. The method as described in claim 3, characterized in that, The first discharge capacity information includes: the first discharge capacity value of the first cell during the first discharge treatment in the first discharge test, and the second discharge capacity value of the first cell during the first discharge test; The second discharge capacity information includes: the third discharge capacity value of the first discharge treatment in the second discharge test of the first cell, and the fourth discharge capacity value of the first cell in the second discharge test.

8. The method as described in claim 7, characterized in that, Based on the first discharge capacity information and the second discharge capacity information, the capacity loss information corresponding to the first cell is determined as follows: The difference between the second discharge capacity value and the fourth discharge capacity value is determined as the capacity loss information.

9. The method as described in claim 7, characterized in that, Based on the first discharge capacity information and the second discharge capacity information, the reversible capacity loss information corresponding to the negative electrode OH region is determined as follows: Determine a first difference between the first discharge capacity value and the third discharge capacity value; Determine a second difference between the second discharge capacity value and the fourth discharge capacity value; The difference between the first difference and the second difference is determined as the reversible capacity loss information.

10. The method as described in claim 7, characterized in that, The third discharge capacity information includes: the fifth discharge capacity value of the second cell after the first discharge test; The fourth discharge capacity information includes: the sixth discharge capacity value of the second cell during the second discharge test.

11. The method as described in claim 10, characterized in that, Based on the first discharge capacity information, the second discharge capacity information, the third discharge capacity information, and the fourth discharge capacity information, the irreversible capacity loss information corresponding to the negative electrode OH region is determined as follows: Determine a third difference between the second discharge capacity value and the fourth discharge capacity value; Determine the fourth difference between the fifth discharge capacity value and the sixth discharge capacity value; The difference between the third difference and the fourth difference is determined as the irreversible capacity loss information.

12. The method as described in claim 1, characterized in that, The storage strategy includes: placing the first battery cell and the second battery cell in an environment with a preset first temperature and keeping them at that temperature for a preset third duration.

13. The method according to any one of claims 1 to 12, characterized in that, Also includes: Based on the capacity loss information and the corresponding storage processing duration, a first curve is constructed to show how the capacity loss information changes with the storage processing duration. And / or, Based on the reversible capacity loss information and the corresponding storage processing duration, a second curve is constructed to show how the reversible capacity loss information changes with the storage processing duration.

14. A cell capacity evaluation device, characterized in that, include: The first test module is used to perform a first discharge test on the first battery cell and the second battery cell according to a preset discharge strategy; wherein the first battery cell is a battery cell with a negative electrode OH region; the second battery cell is a reference battery cell corresponding to the first battery cell, and the second battery cell does not have a negative electrode OH region; The first information acquisition module is used to acquire the first discharge capacity information corresponding to the first cell after the first discharge test. The second test module is used to perform at least one storage process on the first battery cell and the second battery cell according to a preset storage strategy, and after each storage process is completed, to perform a second discharge test on the first battery cell and the second battery cell according to the discharge strategy. The second information acquisition module is used to acquire the second discharge capacity information corresponding to the first cell after the second discharge test. The capacity loss determination module is used to determine the capacity loss information corresponding to the first cell and the reversible capacity loss information corresponding to the negative electrode OH region based on the first discharge capacity information and the second discharge capacity information.

15. An electronic device, characterized in that, include: Memory; and a processor coupled to the memory, the processor being configured to perform the method as described in any one of claims 1 to 13 based on instructions stored in the memory.

16. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that are executed by a processor according to any one of claims 1 to 13.

17. A computer program product, characterized in that, The computer program product stores computer instructions that are executed by a processor using the method as described in any one of claims 1 to 13.

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