Battery capacity determination method, apparatus, device, medium, and product

Abstract

The application discloses a battery capacity determination method, device, equipment, medium and product. The method comprises the following steps: determining at least two charging characteristic voltages of a to-be-tested battery based on a plurality of charging voltage information and a plurality of charging capacity information of the to-be-tested battery; determining at least one discharging characteristic voltage of the to-be-tested battery based on a plurality of discharging voltage information and a plurality of discharging capacity information; determining a current characteristic voltage based on the at least two charging characteristic voltages and the at least one discharging characteristic voltage; determining an offset based on the current characteristic voltage of the to-be-tested battery and a historical characteristic voltage of the to-be-tested battery at a previous moment; and determining a current capacity of the to-be-tested battery based on the offset and a historical capacity of the to-be-tested battery at the previous moment. In this way, the capacity of the battery can be accurately predicted by combining the characteristic voltage reflecting the phase change behavior of the positive and negative electrode materials of the to-be-tested battery.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method, device, equipment, medium and product for determining battery capacity. Background Art

[0002] Currently, power batteries have advantages such as high energy density, rechargeability, safety, and environmental friendliness. Therefore, they are widely used in new energy vehicles, consumer electronics, energy storage systems, and other fields. Lithium-ion batteries inevitably experience capacity decay during use. The industry defines battery capacity as the total amount of energy discharged from a battery at a constant current of 0.33C from 100% state of charge (SOC) at an ambient temperature of 25°C until the battery's SOC drops to 0%.

[0003] However, in practice, to quickly measure battery capacity, the complete capacity test process described above is not performed on the battery cell or battery pack. Instead, the battery management system uses voltage, current, temperature, and historical data to estimate the battery capacity. However, the battery management system is not accurate in calculating the health of some cells. Summary of the Invention

[0004] In view of this, embodiments of the present application provide at least one method, apparatus, device, medium, and product for determining battery capacity.

[0005] The technical solution of the embodiment of the present application is implemented as follows:

[0006] In a first aspect, an embodiment of the present application provides a method for determining battery capacity, the method comprising:

[0007] Acquire first charging data and first discharging data of the battery to be tested, wherein the first charging data includes multiple charging voltage information and multiple charging capacity information that change with time during the charging process; and the first discharging data includes multiple discharging voltage information and multiple discharging capacity information that change with time during the discharging process;

[0008] Determine, based on the multiple charging voltage information and the multiple charging capacity information, at least two charging characteristic voltages corresponding to phase changes of the positive and negative electrode materials of the battery to be tested during the charging process;

[0009] Determine, based on the multiple discharge voltage information and the multiple discharge capacity information, at least one discharge characteristic voltage corresponding to a phase change of the positive and negative electrode materials of the battery to be tested during the discharge process;

[0010] Determining a current characteristic voltage for characterizing capacity attenuation of the battery to be tested based on at least two charging characteristic voltages and at least one discharging characteristic voltage;

[0011] Based on the current characteristic voltage of the battery to be tested and the historical characteristic voltage of the battery to be tested at the previous moment, the voltage offset when the positive and negative electrode materials undergo phase change during the charge and discharge process is determined;

[0012] The current capacity of the battery to be tested is determined based on the voltage offset when the positive and negative electrode materials undergo phase change during the charge and discharge process and the historical capacity of the battery to be tested at the previous moment.

[0013] In an embodiment of the present application, by collecting the voltage and capacity data during the charging and discharging process of the battery to be tested, the charging characteristic voltage and the discharging characteristic voltage that reflect the phase change behavior of the positive and negative electrode materials of the battery to be tested can be determined, and by combining the charging characteristic voltage and the discharging characteristic voltage, the current characteristic voltage that characterizes the capacity attenuation of the battery to be tested is obtained. Then, based on the current characteristic voltage and the historical characteristic voltage, the voltage offset when the positive and negative electrode materials undergo phase change during the charging and discharging process is determined; finally, based on the offset and the historical capacity, the current capacity of the battery to be tested is determined. In this way, by combining the charging characteristic voltage and the discharging characteristic voltage that reflect the phase change behavior of the positive and negative electrode materials of the battery to be tested, the voltage offset caused by factors such as material structure changes and active material loss during the battery aging process can be accurately captured, thereby improving the accuracy of the current capacity determined based on the offset and the historical capacity of the battery to be tested at the previous moment.

[0014] In some embodiments, based on at least two charging characteristic voltages and at least one discharge characteristic voltage, a current characteristic voltage used to characterize the capacity attenuation of the battery to be tested is determined, including: determining a first voltage deviation that characterizes the degree of change between the phase change resistances of different phase changes of the positive and negative electrode materials during the charging process based on at least two charging characteristic voltages; determining a second voltage deviation based on a target charging characteristic voltage among the at least two charging characteristic voltages and at least one discharge characteristic voltage; the second voltage deviation is used to characterize the degree of change between the phase change resistance of the positive and negative electrode materials during the charging process and the phase change resistance of the positive and negative electrode materials during the discharging process; determining the current characteristic voltage based on the first voltage deviation and the second voltage deviation.

[0015] In the embodiments of this application, by separately determining the voltage deviations at different phase change stages during the charging process, as well as the voltage deviations between the charging and discharging processes, we can more comprehensively reflect the changing trend of the material phase change resistance during battery aging, and thus accurately determine the current battery capacity decay. This multi-dimensional deviation analysis method helps to more accurately identify the key inflection points of battery capacity decay, improve the sensitivity and accuracy of capacity estimation, and reduce the risk of misjudgment caused by a single deviation indicator.

[0016] In some embodiments, based on multiple charging voltage information and multiple charging capacity information, at least two charging characteristic voltages corresponding to phase changes in the positive and negative electrode materials of the battery to be tested during the charging process are determined, including: constructing a first differential capacity voltage curve of the battery to be tested during the charging process based on multiple charging voltage information and multiple charging capacity information; determining the charging voltages corresponding to at least two peaks of the first differential capacity voltage curve as at least two charging characteristic voltages; based on multiple discharge voltage information and multiple discharge capacity information, at least one discharge characteristic voltage corresponding to phase changes in the positive and negative electrode materials of the battery to be tested during the discharge process is determined, including: constructing a second differential capacity voltage curve of the battery to be tested during the discharge process based on multiple discharge voltage information and multiple discharge capacity information; determining the discharge voltage corresponding to at least one peak of the second differential capacity voltage curve as at least one discharge characteristic voltage; wherein, the voltage ranges corresponding to the multiple charging voltage information and the multiple discharge voltage information are smaller than the voltage range corresponding to the complete charge and discharge of the battery to be tested.

[0017] In this embodiment, by constructing a differential capacity-voltage curve and extracting its peak position, the key voltage nodes of material phase transitions during battery charge and discharge can be efficiently and stably identified. Compared to the related art method that requires a complete charge and discharge cycle to obtain capacity, this embodiment can extract characteristic voltages and predict battery capacity using test data from a partial voltage range, significantly reducing testing costs and time, while also reducing data fluctuations caused by unstable testing environments.

[0018] In some embodiments, the charging voltages corresponding to at least two peaks of the first differential capacity voltage curve are determined as at least two charging characteristic voltages, including: determining the charging voltage corresponding to the maximum peak of the first differential capacity voltage curve as the first charging characteristic voltage among the at least two charging characteristic voltages; and determining the charging voltage corresponding to the peak in the starting direction of the first differential capacity voltage curve and adjacent to the maximum peak as the second charging characteristic voltage among the at least two charging characteristic voltages.

[0019] In the embodiment of the present application, by selecting the most significant peak in the differential capacity curve and adjacent peaks as the charging characteristic voltage, the battery capacity change trend can be accurately determined.

[0020] In some embodiments, the current capacity of the battery to be tested is determined based on the voltage offset when the positive and negative electrode materials undergo phase change during the charging and discharging process and the historical capacity of the battery to be tested at the previous moment, including: determining the capacity decay rate of the battery to be tested based on the voltage offset and a preset corresponding relationship; the preset corresponding relationship is the correspondence between the capacity decay rate and the voltage of the battery to be tested; and determining the current capacity of the battery to be tested based on the historical capacity and capacity decay rate of the battery to be tested.

[0021] In the embodiments of the present application, by pre-establishing the mapping relationship between the capacity attenuation rate and the voltage offset, the dynamic updating of the current capacity of the battery can be realized without relying on external calibration data.

[0022] In some embodiments, the method further comprises: under a preset environment, performing multiple capacity tests on a test battery corresponding to the battery type and the to-be-tested battery, to obtain multiple test data corresponding to each capacity test; the test data includes test voltage information and test capacity information; determining a test characteristic voltage of the test battery in each capacity test based on the test voltage information and the test capacity information corresponding to each capacity test; and determining a preset corresponding relationship between the capacity attenuation rate and the characteristic voltage of the to-be-tested battery based on the multiple test characteristic voltages and the test capacity information corresponding to the test characteristic voltages.

[0023] In the embodiments of the present application, by performing multiple tests on the same type of battery under standard conditions and extracting the relationship between the characteristic voltage and the capacity change, a representative capacity attenuation model (i.e., the preset corresponding relationship) can be constructed. In this way, the current capacity of the battery can be quickly and accurately predicted through the capacity attenuation model, and the capacity attenuation model can also be used to predict the capacity of the same type of battery, thereby improving the applicability of capacity prediction.

[0024] In some embodiments, determining the preset corresponding relationship based on the multiple test characteristic voltages and the test capacity information corresponding to the test characteristic voltages comprises: performing differential processing on a voltage sequence including the multiple test characteristic voltages to obtain multiple test voltage difference values; the voltage sequence is obtained by sorting the multiple test characteristic voltages according to the capacity test time; determining the test capacity attenuation rate of the test battery at different capacity test times based on the multiple test capacity information; and performing fitting processing on the multiple test capacity attenuation rates and the multiple test voltage difference values to obtain the preset corresponding relationship.

[0025] In the embodiments of the present application, the differential values of the test characteristic voltages are obtained through differential processing. The test capacity attenuation rate is determined according to the test capacity information, and further fitting processing is performed to establish the preset corresponding relationship. Through the above method, the voltage and capacity change trends of the battery at different use stages can be accurately captured, so that the capacity attenuation of the test battery can be efficiently predicted, thereby realizing real-time monitoring and risk warning of the health state of the test battery.

[0026] In some embodiments, the test data also includes test current information; based on the test voltage information and test capacity information corresponding to each capacity test, the test characteristic voltage of the test battery in each capacity test is determined, including: for the test voltage information corresponding to each sampling time of each capacity test, based on the test current information corresponding to the sampling time, the preset test current in the capacity test, and the polarization resistance of the test battery corresponding to the test voltage information, the normalization parameter of the test characteristic voltage is determined; the preset test current is obtained from the test current information in a preset manner; based on the normalization parameter of the test characteristic voltage, the test voltage information is normalized to obtain the processed test voltage information; based on the processed test voltage information and test capacity information, the test characteristic voltage of the test battery in each capacity test is determined.

[0027] In the embodiments of the present application, by introducing test current information and normalizing it with the polarization resistance of the test battery, the effects of charge and discharge current fluctuations on the voltage can be effectively eliminated. By introducing test current information and normalizing it with the polarization resistance of the test battery, the accuracy of the test voltage data can be improved, thereby obtaining a more reliable test characteristic voltage and, in turn, enabling a more accurate prediction of the capacity decay of the test battery.

[0028] In a second aspect, an embodiment of the present application provides a device for determining battery capacity, the device comprising:

[0029] an acquisition module, configured to acquire first charging data and first discharging data of the battery to be tested, wherein the first charging data includes a plurality of charging voltage information and a plurality of charging capacity information that vary with time during the charging process; and the first discharging data includes a plurality of discharging voltage information and a plurality of discharging capacity information that vary with time during the discharging process;

[0030] A first voltage determination module is configured to determine, based on the plurality of charging voltage information and the plurality of charging capacity information, at least two charging characteristic voltages corresponding to phase changes of the positive and negative electrode materials of the battery to be tested during the charging process;

[0031] A second voltage determination module is configured to determine, based on the plurality of discharge voltage information and the plurality of discharge capacity information, at least one discharge characteristic voltage corresponding to a phase change of the positive and negative electrode materials of the battery to be tested during the discharge process;

[0032] a third voltage determination module, configured to determine a current characteristic voltage for characterizing the capacity attenuation of the battery to be tested based on at least two charging characteristic voltages and at least one discharging characteristic voltage;

[0033] A voltage offset determination module is used to determine the voltage offset of the positive and negative electrode materials when a phase change occurs during the charge and discharge process based on the current characteristic voltage of the battery to be tested and the historical characteristic voltage of the battery to be tested at the previous moment;

[0034] The capacity determination module is used to determine the current capacity of the battery to be tested based on the voltage offset when the positive and negative electrode materials undergo phase change during the charging and discharging process and the historical capacity of the battery to be tested at the previous moment.

[0035] In a third aspect, an embodiment of the present application provides a battery capacity determination device, comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor executes the program, some or all of the steps in the above method are implemented.

[0036] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, which implements some or all of the steps in the above method when executed by a processor.

[0037] In a fifth aspect, an embodiment of the present application provides a computer program product, which implements some or all of the steps in the above method when the computer program or instructions are executed by a processor.

[0038] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and do not limit the technical solutions of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings herein are incorporated into and constitute a part of the specification. These drawings illustrate embodiments consistent with the present application and, together with the specification, are used to illustrate the technical solutions of the present application.

[0040] Figure 1 A schematic diagram of the implementation process of a battery capacity determination method provided in an embodiment of the present application Figure 1 ;

[0041] Figure 2 A schematic diagram of the implementation process of a battery capacity determination method provided in an embodiment of the present application Figure 2 ;

[0042] Figure 3 A schematic diagram of the implementation process of a battery capacity determination method provided in an embodiment of the present application Figure 3 ;

[0043] Figure 4 A schematic diagram of the implementation process of a battery capacity determination method provided in an embodiment of the present application Figure 4 ;

[0044] Figure 5 A schematic diagram of the implementation process of a battery capacity determination method provided in an embodiment of the present application Figure 5 ;

[0045] Figure 6 Schematic diagram of the differential capacity voltage curve of the battery to be tested provided in the embodiment of the present application Figure 1 ;

[0046] Figure 7 Schematic diagram of the differential capacity voltage curve of the battery to be tested provided in the embodiment of the present application Figure 2 ;

[0047] Figure 8 Schematic diagram of the relationship between the test charging characteristic voltage and the actual capacity provided in the embodiment of the present application Figure 1 ;

[0048] Figure 9 Schematic diagram of the relationship between the test charging characteristic voltage and the actual capacity provided in the embodiment of the present application Figure 2 ;

[0049] Figure 10 A schematic diagram showing the relationship between the discharge characteristic voltage and the actual capacity of the test provided in an embodiment of the present application;

[0050] Figure 11 Schematic diagram of the relationship between the charge and discharge characteristic voltage and actual capacity provided in the embodiment of the present application Figure 1 ;

[0051] Figure 12 Schematic diagram of the relationship between the charge and discharge characteristic voltage and actual capacity provided in the embodiment of the present application Figure 2 ;

[0052] Figure 13 Schematic diagram of the relationship between the charge and discharge characteristic voltage and actual capacity provided in the embodiment of the present application Figure 3 ;

[0053] Figure 14 Schematic diagram of the relationship between the charge and discharge characteristic voltage and actual capacity provided in the embodiment of the present application Figure 4 ;

[0054] Figure 15 A schematic diagram showing the relationship between the characteristic voltage of a battery and the battery usage time during the charging process provided in an embodiment of the present application;

[0055] Figure 16 A schematic diagram showing the relationship between the characteristic voltage of a battery and the battery usage time during the discharge process provided in an embodiment of the present application;

[0056] Figure 17 A schematic diagram of a preset correspondence between the capacity decay rate and the characteristic voltage of a battery to be tested provided in an embodiment of the present application;

[0057] Figure 18 A schematic diagram of the implementation process of a battery capacity determination method provided in an embodiment of the present application Figure 6 ;

[0058] Figure 19 A schematic diagram of the structure of a battery capacity determination device provided in an embodiment of the present application;

[0059] Figure 20 A hardware entity diagram of a battery capacity determination device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions of this application are further elaborated in detail below with reference to the accompanying drawings and embodiments. The described embodiments should not be regarded as limiting this application. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0061] In the following description, references to "some embodiments" describe a subset of all possible embodiments. However, it is understood that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict. The terms "first / second / third" are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It is understood that the specific order or sequence of "first / second / third" may be interchanged where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing this application only and are not intended to limit this application.

[0063] The present invention provides a method for determining battery capacity, which can be executed by a processor of a computer device, wherein the computer device may refer to a device with data processing capabilities, such as a server, a laptop, a tablet computer, a desktop computer, or a mobile device.

[0064] Figure 1 A schematic diagram of the implementation process of a battery capacity determination method provided in an embodiment of the present application Figure 1 ,like Figure 1 As shown, the method includes the following steps S101 to S106:

[0065] Step S101, obtaining first charging data and first discharging data of the battery to be tested, wherein the first charging data includes multiple charging voltage information and multiple charging capacity information that change with time during the charging process; the first discharging data includes multiple discharging voltage information and multiple discharging capacity information that change with time during the discharging process.

[0066] In the embodiment of the present application, the battery under test can be charged to obtain multiple charging voltage information that changes over time during the charging process, as well as multiple charging capacity information that changes over time. The battery under test can also be discharged to obtain multiple discharge voltage information that changes over time during the discharge process, as well as multiple discharge capacity information that changes over time. In other words, the multiple charging voltage information and the multiple charging capacity information are in one-to-one correspondence, and the multiple discharge voltage information and the multiple discharge voltage information are in one-to-one correspondence.

[0067] In the embodiment of the present application, the charging voltage range corresponding to the multiple charging voltage information and the discharge voltage range corresponding to the multiple discharge voltage information are both smaller than the voltage range corresponding to the complete charge and discharge of the battery under test. The complete charge and discharge of the battery under test includes a discharge process of the battery under test from 100% SOC to 0% SOC and a charge process of the battery under test from 0% SOC to 100% SOC.

[0068] It is understandable that in actual application scenarios, in order to obtain the current capacity of the battery to be tested as quickly as possible, the battery is generally not fully charged and discharged. Therefore, the charging voltage range corresponding to the multiple charging voltage information and the discharge voltage range corresponding to the multiple discharge voltage information in the embodiments of the present application are both smaller than the voltage range corresponding to the complete charge and discharge of the battery to be tested. Exemplarily, the above-mentioned charging voltage range and the above-mentioned discharge voltage range can be 3.5V~3.8V, while the voltage range corresponding to the complete charge and discharge of the battery to be tested can be 2.8~4.35V.

[0069] In the embodiment of the present application, during the charging process or the discharging process of the battery to be tested, a plurality of charge and discharge voltage information and corresponding charge and discharge capacity information may be collected according to a preset collection time interval.

[0070] Step S102 : determining, based on the plurality of charging voltage information and the plurality of charging capacity information, at least two charging characteristic voltages corresponding to phase changes of the positive and negative electrode materials of the battery to be tested during the charging process.

[0071] In an embodiment of the present application, a differential capacity curve (i.e., a DQ / DV-V curve) of the battery to be tested during the charging process can be constructed based on multiple charging voltage information and multiple charging capacity information. Then, the positive and negative electrode materials of the battery to be tested are selected on the differential capacity curve, and at least two charging characteristic voltages corresponding to the phase change during the charging process are selected.

[0072] For example, in the case of a ternary lithium battery, the positive electrode material is a ternary positive electrode material (e.g., nickel-cobalt-manganese), and the negative electrode material is a carbon material. During charging, lithium ions in the ternary positive electrode material are released, causing a phase change in the positive electrode material. The lithium ions in the ternary positive electrode material are then intercalated between graphite layers, causing a phase change in the negative electrode material. By constructing a differential capacity curve for the battery during charging, it is possible to determine at least two characteristic charging voltages corresponding to phase changes in the positive and negative electrode materials of the battery during charging.

[0073] Step S103 , based on the multiple discharge voltage information and the multiple discharge capacity information, determining at least one discharge characteristic voltage corresponding to a phase change of the positive and negative electrode materials of the battery to be tested during the discharge process.

[0074] In an embodiment of the present application, a differential capacity curve (i.e., a DQ / DV-V curve) of the battery to be tested during the discharge process can be constructed based on multiple discharge voltage information and multiple discharge capacity information. Then, the positive and negative electrode materials of the battery to be tested are selected on the differential capacity curve, and at least two discharge characteristic voltages corresponding to the phase change during the discharge process are selected.

[0075] For example, in the case of a ternary lithium battery, the positive electrode material is a ternary positive electrode material (e.g., nickel-cobalt-manganese), and the negative electrode material is a carbon material. During discharge, lithium ions are released from the carbon material, causing a phase change in the carbon material. The lithium ions in the carbon material are then reinserted into the positive electrode material, causing a phase change in the positive electrode material. By constructing a differential capacity curve for the battery during discharge, it is possible to determine at least two characteristic discharge voltages corresponding to phase changes in the positive and negative electrode materials of the battery during discharge.

[0076] Step S104 : determining a current characteristic voltage for characterizing the capacity attenuation of the battery to be tested based on at least two charging characteristic voltages and at least one discharging characteristic voltage.

[0077] In an embodiment of the present application, at least two charging characteristic voltages and at least one discharging characteristic voltage can be brought into the relationship between the charging characteristic voltage, the discharging characteristic voltage, and the current characteristic voltage to obtain the current characteristic voltage of the battery to be tested. Determining the relationship between the charging characteristic voltage, the discharging characteristic voltage, and the current characteristic voltage may include: testing the test battery in a laboratory environment to obtain multiple test points, and then fitting the multiple test points to obtain the relationship between the charging characteristic voltage, the discharging characteristic voltage, and the current characteristic voltage. The test points are the charging characteristic voltage, the discharging characteristic voltage, and the current characteristic voltage at different sampling points. The battery type of the test battery is the same as the type of the battery to be tested.

[0078] It is understandable that as the battery to be tested is used, the phase change voltage of the battery to be tested (i.e., the charging characteristic voltage and the discharge characteristic voltage) will shift due to the influence of thermodynamic factors such as the gradual change of the electrode material structure of the battery to be tested and the loss of active materials. Therefore, the current characteristic voltage obtained by combining at least two charging characteristic voltages and at least one discharge characteristic voltage can more accurately describe the offset of the phase change voltage of the battery to be tested, thereby obtaining the capacity attenuation of the battery to be tested due to the influence of thermodynamic factors.

[0079] Step S105 , based on the current characteristic voltage of the battery to be tested and the historical characteristic voltage of the battery to be tested at the previous moment, determining the voltage offset when the positive and negative electrode materials undergo phase change during the charge and discharge process.

[0080] Here, the historical characteristic voltage refers to the characteristic voltage value obtained by testing at the previous moment. The offset is used to determine the capacity attenuation change of the battery under test.

[0081] In the embodiment of the present application, the difference between the current characteristic voltage and the historical characteristic voltage of the battery to be tested can be determined as the voltage offset when the positive and negative electrode materials undergo phase change during the charging and discharging process.

[0082] It can be understood that the voltage when the positive and negative electrode materials undergo phase change during the charging and discharging process corresponds to the capacity attenuation of the battery to be tested. Therefore, the capacity attenuation change of the battery to be tested equivalent to the previous moment can be determined by the voltage offset when the positive and negative electrode materials undergo phase change.

[0083] Step S106 , determining the current capacity of the battery to be tested based on the voltage offset when the positive and negative electrode materials undergo phase change during the charge and discharge process and the historical capacity of the battery to be tested at the previous moment.

[0084] Here, the historical capacity of the battery to be tested may be a capacity determined based on the historical characteristic voltage of the battery to be tested at the last moment.

[0085] In an embodiment of the present application, the capacity attenuation change of the battery to be tested can be determined by first determining the voltage offset when the positive and negative electrode materials undergo phase change during the charging and discharging process, and then the current capacity of the battery to be tested can be determined based on the capacity attenuation change of the battery to be tested and the historical capacity of the battery to be tested at the previous moment.

[0086] For example, when the historical capacity of the battery to be tested at the last moment is Q i-1 , through the voltage offset when the positive and negative electrode materials undergo phase change during the charge and discharge process, it is determined that the capacity attenuation change of the battery to be tested is -0.5%, then Q i-1 ×0.5% is determined as the current capacity Q i .

[0087] In some embodiments, when the capacity of the battery to be tested is currently being determined for the first time, the historical capacity at the last moment may be the rated capacity of the battery to be tested.

[0088] In an embodiment of the present application, by collecting the voltage and capacity data during the charging and discharging process of the battery to be tested, the charging characteristic voltage and the discharging characteristic voltage that reflect the phase change behavior of the positive and negative electrode materials of the battery to be tested can be determined, and by combining the charging characteristic voltage and the discharging characteristic voltage, the current characteristic voltage that characterizes the capacity attenuation of the battery to be tested is obtained. Then, based on the current characteristic voltage and the historical characteristic voltage, the voltage offset when the positive and negative electrode materials undergo phase change during the charging and discharging process is determined; finally, based on the offset and the historical capacity, the current capacity of the battery to be tested is determined. In this way, by combining the charging characteristic voltage and the discharging characteristic voltage that reflect the phase change behavior of the positive and negative electrode materials of the battery to be tested, the voltage offset caused by factors such as material structure changes and active material loss during the battery aging process can be accurately captured, thereby improving the accuracy of the current capacity determined based on the offset and the historical capacity of the battery to be tested at the previous moment.

[0089] In some embodiments, as Figure 2 As shown, the above step S104 can be implemented through steps S201 to S203:

[0090] Step S201: determining a first voltage deviation representing a degree of change between phase change resistances of different phase changes of positive and negative electrode materials during charging based on at least two charging characteristic voltages.

[0091] Here, different charging characteristic voltages correspond to different phase change processes.

[0092] For example, in the case where the battery to be tested is a ternary lithium battery, the at least two charging characteristic voltages may include a first charging characteristic voltage and a second charging characteristic voltage, wherein the first charging characteristic voltage may correspond to the positive and negative electrode materials changing from LiC to H during the charging process. 24 Converted to LiC 12 The voltage corresponding to the phase change process of the second charging characteristic voltage can correspond to the phase change of the positive and negative electrode materials from LiC 12 The voltage corresponding to the phase change process of LiC6. 24 Converted to LiC 12 The phase transition difficulty is less than that of LiC 12 The phase change difficulty of converting to LiC6 is such that the first charging characteristic voltage is smaller than the second charging characteristic voltage.

[0093] In the embodiment of the present application, the difference between at least two charging characteristic voltages may be determined as the first voltage deviation.

[0094] It is understandable that when the battery to be tested is a ternary lithium battery, when the battery to be tested is in a healthy state, the first voltage deviation is fixed. When the battery to be tested ages, the distance between graphite layers is distorted due to repeated insertion / extraction, or the solid electrolyte interface (SEI) film becomes thicker and hinders lithium diffusion, resulting in a low lithium content stage (LiC 24 →LiC 12 ) increases, causing the first charge characteristic voltage to shift in the direction of increase. In the high lithium content stage (LiC 12 →LiC6) embedding resistance increases, causing the second charge characteristic voltage to shift in the direction of increase. 24 →LiC 12 The phase change resistance is less than that of LiC 12 →LiC6 phase change resistance, so the offset of the first charging characteristic voltage is smaller than the offset of the second charging characteristic voltage. Therefore, by determining the difference between the first and second charging characteristic voltages, the degree of degradation of the graphite embedding power can be reflected, and thus the capacity decay of the battery under test.

[0095] Step S202, determining a second voltage deviation based on a target charging characteristic voltage among at least two charging characteristic voltages and at least one discharge characteristic voltage; the second voltage deviation is used to characterize the phase change resistance of the positive and negative electrode materials during the charging process, and the degree of change between the phase change resistance of the positive and negative electrode materials during the discharge process.

[0096] Here, the target charging characteristic voltage may refer to any of the at least two charging characteristic voltages. In some embodiments, the target charging characteristic voltage may refer to the charging characteristic voltage with a smaller voltage value among the at least two charging characteristic voltages.

[0097] For example, when the battery to be tested is a ternary lithium battery, the discharge characteristic voltage may correspond to the conversion of the positive and negative electrode materials from LiC6 to LiC during the discharge process. 12 The voltage corresponding to the phase change process.

[0098] In the embodiment of the present application, the difference between the target charging characteristic voltage and the discharging characteristic voltage may be determined as the second voltage deviation.

[0099] It is understandable that when the battery to be tested is a ternary lithium battery, when the battery to be tested is in a healthy state, the second voltage deviation is fixed. When the battery to be tested ages, the graphite layer spacing is distorted due to repeated insertion / extraction, or the SEI film thickens and hinders lithium diffusion, which will cause LiC6 to convert to LiC 12The embedding resistance of the positive and negative electrode materials is reduced, so that the discharge characteristic voltage is offset in the direction of reduction, and the target charging characteristic voltage is offset in the direction of increase. Therefore, by determining the difference between the charging characteristic voltage and the discharge characteristic voltage, the change degree between the phase change resistance of the positive and negative electrode materials in the charging process and the phase change resistance of the positive and negative electrode materials in the discharging process can be reflected.

[0100] In step S203, the current characteristic voltage is determined based on the first voltage deviation and the second voltage deviation.

[0101] In the embodiments of the present application, the product of the first voltage deviation and the second voltage deviation can be determined as the current characteristic voltage.

[0102] It can be understood that the first voltage deviation is used to represent the change degree between the phase change resistances of the positive and negative electrode materials in the charging process, and the second voltage deviation is used to represent the change degree between the phase change resistance of the positive and negative electrode materials in the charging process and the phase change resistance of the positive and negative electrode materials in the discharging process. By calculating the product of the two, the change of the phase change resistance of the positive and negative electrode materials in the charging and discharging process can be more obviously embodied, and the change of the phase change resistance of the positive and negative electrode materials in the charging and discharging process can reflect the capacity attenuation degree of the current battery.

[0103] In the embodiments of the present application, the current characteristic voltage can be realized by formula (1):

[0104] (v4-v5)(v4-v6) formula (1);

[0105] Wherein, v4, v5 is the charging characteristic voltage, and v4 is less than v5, v6 is the discharging characteristic voltage.

[0106] In the embodiments of the present application, by respectively determining the voltage deviation of different phase change stages in the charging process and the voltage deviation between the charging process and the discharging process, the change trend of the material phase change resistance in the battery aging process can be more comprehensively reflected, and the capacity attenuation degree of the current battery can be accurately determined. This multi-dimensional deviation analysis method helps to more accurately identify the key inflection point of battery capacity attenuation, improve the sensitivity and accuracy of capacity estimation, and reduce the misjudgment risk that may be caused by a single deviation index.

[0107] In some embodiments, as shown in Figure 3 The above step S102 can be realized by step S301 and step S302, and the above step S103 can be realized by step S303 and step S304:

[0108] In step S301, based on the plurality of charging voltage information and the plurality of charging capacity information, a first differential capacity voltage curve of the battery to be tested in the charging process is constructed.

[0109] The differential capacity-voltage curve (DQ / DV-V curve) is a curve derived by differentially processing the voltage and capacity data collected during the battery's charge and discharge process. The differential capacity-voltage curve reflects the changes in the battery's capacity required to charge or discharge a unit voltage at different voltages, thereby revealing the phase change behavior of the electrode material during the charge and discharge process.

[0110] In the embodiment of the present application, by constructing the first differential capacity-voltage curve, the phase change position of the electrode material during the charging process can be more intuitively identified, thereby providing a basis for the subsequent determination of the charging characteristic voltage.

[0111] Step S302 : determining charging voltages corresponding to at least two peaks of the first differential capacity-voltage curve as at least two charging characteristic voltages.

[0112] Here, the peak refers to the position of the local maximum value in the first differential capacity-voltage curve, representing a significant point where the phase transition of the battery under test occurs within a specific voltage range.

[0113] For example, when the battery to be tested is a ternary lithium battery, two main peaks may be observed in the charging stage, corresponding to LiC 24 →LiC 12 and LiC 12 →The phase change process of LiC6. The voltage points corresponding to these two main peaks are of great significance for judging the degree of battery aging.

[0114] Step S303 : constructing a second differential capacity-voltage curve of the battery under test during the discharge process based on the plurality of discharge voltage information and the plurality of discharge capacity information.

[0115] In the embodiment of the present application, similar to the charging process, the differential capacity-voltage curve during the discharge process also reflects the phase change behavior of the electrode material at different voltages.

[0116] Step S304 : determining a discharge voltage corresponding to at least one peak of the second differential capacity-voltage curve as at least one discharge characteristic voltage.

[0117] In the embodiment of the present application, the voltage corresponding to the maximum peak in the second differential capacity voltage curve can be determined as the discharge characteristic voltage. For example, in the case where the battery to be tested is a ternary lithium battery, the negative electrode material LiC6 is LiC 12 The voltage point corresponding to the transition is the voltage corresponding to the maximum peak of the second differential capacity-voltage curve.

[0118] In the embodiment of the present application, the voltage ranges corresponding to the plurality of charging voltage information and the plurality of discharging voltage information are respectively smaller than the voltage range corresponding to the complete charge and discharge of the battery to be tested.

[0119] Exemplarily, the voltage range corresponding to the multiple charging voltage information is [a, b], the voltage range corresponding to the multiple discharging voltage information is [c, d], and the voltage range corresponding to the full charge and discharge of the battery is [e, f], where e is less than a and less than c, and f is greater than b and greater than d. In other words, the voltage ranges corresponding to the above-mentioned multiple charging voltage information and multiple discharging voltage information respectively belong to a subset of the voltage range corresponding to the full charge and discharge of the battery to be tested. In the case where the battery to be tested is a ternary lithium battery, the voltage range corresponding to the multiple charging voltage information and the multiple discharging voltage information respectively can be 3.5~3.8V, and the voltage range corresponding to the full charge and discharge of the battery to be tested can be 2.8~4.35V. At the same time, the current state of charge of the battery to be tested corresponding to 3.5~3.8V is above 50%, so the data error is small.

[0120] Understandably, in actual application scenarios, in order to quickly determine the current capacity of the battery under test, the battery is generally not fully charged or discharged. Furthermore, the voltage values ​​corresponding to the main phase transitions of the battery under test are relatively concentrated, so the battery under test can be charged and discharged within a smaller voltage range, and the characteristic charging and discharging voltages can be collected.

[0121] In this embodiment, by constructing a differential capacity-voltage curve and extracting its peak position, the key voltage nodes of material phase transitions during battery charge and discharge can be efficiently and stably identified. Compared to the related art method that requires a complete charge and discharge cycle to obtain capacity, this embodiment can extract characteristic voltages and predict battery capacity using test data from a partial voltage range, significantly reducing testing costs and time, while also reducing data fluctuations caused by unstable testing environments.

[0122] In some embodiments, the above step S302 may be implemented through steps S3021 and S3022:

[0123] Step S3021 : determining the charging voltage corresponding to the maximum peak of the first differential capacity-voltage curve as the first charging characteristic voltage among the at least two charging characteristic voltages.

[0124] Here, the maximum peak refers to the peak with the largest amplitude that appears in the first differential capacity-voltage curve (DQ / DV-V curve). This maximum peak usually corresponds to the voltage point where the battery under test undergoes a significant phase change during the charge and discharge process. For example, in the case of a ternary lithium battery, the negative electrode material LiC 12 The voltage point corresponding to the transition to LiC6 is the voltage corresponding to the maximum peak of the first differential capacity-voltage curve.

[0125] Step S3022: Determine the charging voltage corresponding to the peak adjacent to the maximum peak in the starting direction of the first differential capacity-voltage curve as the second charging characteristic voltage among the at least two charging characteristic voltages.

[0126] Here, the starting direction refers to the direction of increasing from high voltage to low voltage on the first differential capacity voltage curve. The peak adjacent to the maximum peak refers to the next peak next to the maximum peak in the starting direction. The peak adjacent to the maximum peak usually corresponds to another important phase change process. For example, in the case of a ternary lithium battery, the negative electrode material LiC 24 Xiang LiC 12 The voltage point corresponding to the transition is the charging voltage corresponding to the peak in the direction of the starting point of the first differential capacity-voltage curve and adjacent to the maximum peak.

[0127] In the embodiment of the present application, by selecting the most significant peak in the differential capacity curve and adjacent peaks as the charging characteristic voltage, the battery capacity change trend can be accurately determined.

[0128] In some embodiments, as Figure 4 As shown, the above step S106 can be implemented through steps S401 and S402:

[0129] Step S401 : determining the capacity decay rate of the battery to be tested based on the voltage offset and a preset corresponding relationship; the preset corresponding relationship is the corresponding relationship between the capacity decay rate of the battery to be tested and the voltage.

[0130] In an embodiment of the present application, multiple charge and discharge processes can be performed on a test battery corresponding to the battery type to be tested in advance, and then multiple differential capacity-voltage curves can be constructed based on the data collected during the multiple charge and discharge processes to obtain the characteristic voltage corresponding to each charge and discharge process, and then the above-mentioned preset corresponding relationship can be determined based on the multiple characteristic voltages and the test capacities corresponding to the multiple characteristic voltages.

[0131] In the embodiment of the present application, the voltage offset can be brought into the preset corresponding relationship to obtain the capacity attenuation rate of the battery to be tested.

[0132] In some embodiments, the preset corresponding relationship can be expressed by formula (2):

[0133] Y=aX+b(2);

[0134] Wherein, Y is the capacity decay rate, X is the voltage offset, and a and b are constants. For example, in the case of a ternary lithium battery, a can be 0.0298428714429867, and b can be 0.00828035090706023.

[0135] Step S402 : determining the current capacity of the battery to be tested based on the historical capacity and capacity decay rate of the battery to be tested.

[0136] In the embodiment of the present application, the product of the historical capacity of the battery to be tested and the capacity decay rate can be determined as the current capacity of the battery to be tested.

[0137] In the embodiment of the present application, the above step S402 can be implemented by formula (3):

[0138] Q i =Q i-1 (1+Y) formula (3);

[0139] Among them, Q i is the current capacity of the battery to be tested, Q i-1 is the historical capacity of the battery under test, and Y is the capacity decay rate. It should be noted that because the capacity decay rate is the capacity decay rate of the battery under test relative to the previous moment, Y is a negative value.

[0140] In the embodiment of the present application, by pre-establishing a mapping relationship between the capacity decay rate and the voltage offset, the current capacity of the battery can be dynamically updated without relying on external calibration data.

[0141] In some embodiments, as Figure 5 As shown, the above method can also be implemented through steps S501 to S503:

[0142] Step S501 , under a preset environment, performing multiple capacity tests on a test battery whose battery type corresponds to the battery to be tested, and obtaining multiple test data corresponding to each capacity test; the test data includes test voltage information and test capacity information.

[0143] Here, the preset environment refers to a standardized test environment used to simulate actual battery usage conditions. Test data refers to the electrical parameters collected during the capacity test, primarily including test voltage information (i.e., the change in terminal voltage during the battery's charge and discharge process) and test capacity information.

[0144] In the embodiment of the present application, a capacity test may be performed on the test battery at preset intervals, wherein one capacity test may include one discharge process and one charge process.

[0145] For example, a capacity test of a test battery can be implemented as shown in Table 1:

[0146] Table 1

[0147]

[0148] Table 1 is a schematic diagram of the steps for performing a capacity test on a test battery. As shown in Table 1, when the test environment temperature is stable at 25°C, the steps for performing a capacity test on the test battery include the following steps:

[0149] Step 1: Initially test the battery at rest for 5 minutes.

[0150] Step 2: Discharge the battery at a constant current rate of 1 / 3C (current = battery nominal capacity × 1 / 3, e.g., a nominal 10Ah battery corresponds to 3.33A) until the battery voltage drops to 2.8V (discharge cutoff voltage, corresponding to 0% SOC). Record the real-time voltage every 30 seconds during discharge (i.e., obtain test voltage information during the discharge process).

[0151] Step 3: Test the battery at rest for 5 minutes.

[0152] Step 4, Constant Current (CC) Phase: Charge the battery at a 1 / 3C rate until the voltage reaches 4.35V. Constant Voltage (CV) Phase: Maintain a stable voltage at 4.35V while gradually decreasing the charging current until it reaches 0.05C. During charging, record the real-time voltage every 30 seconds (i.e., obtain test voltage information during the charging process).

[0153] Step 5: Test the battery at rest for 5 minutes.

[0154] Step 6: Discharge at a constant current rate of 1 / 3C until the voltage drops to 2.8V. During this period, record the cumulative discharge capacity (i.e., test capacity information) every 30 seconds.

[0155] Step 7: Test the battery at rest for 5 minutes.

[0156] In the embodiment of the present application, a capacity test is performed every preset time according to the steps shown in Table 1, thereby obtaining multiple test data corresponding to the multiple capacity tests.

[0157] Step S502 : determining a test characteristic voltage of the test battery in each capacity test based on the test voltage information and the test capacity information corresponding to each capacity test.

[0158] In the embodiment of the present application, for each capacity test, a DQ / DV-V curve corresponding to the charge and discharge process of the test battery can be constructed based on the test voltage information and test capacity information corresponding to the capacity test.

[0159] For example, Figure 6 As shown, the voltage is differentiated by the charge / discharge capacity of the battery to obtain DQ / DV. DQ / DV is plotted as the Y axis and the voltage V as the X axis to obtain Figure 6The DQ / DV-V curves shown. The first curve 601 is the DQ / DV-V curve corresponding to the charging process, and the second curve 602 is the DQ / DV-V curve corresponding to the discharging process.

[0160] In some embodiments, due to the abnormal points caused by fluctuating noise during the test process, the test data is fitted by the method of spline interpolation. The smoothness of the fitting can be 0.00001.

[0161] Exemplarily, as Figure 7 shown, Figure 7 the curve obtained by fitting the curve in Figure 6 .

[0162] In the embodiments of the present application, at least two test charging characteristic voltages corresponding to the charging process and at least one test discharging characteristic voltage corresponding to the discharging process can be obtained based on the DQ / DV-V curves corresponding to the charging and discharging processes, and then the test characteristic voltage in the capacity test of the test battery can be determined based on the at least two test charging characteristic voltages and the at least one test discharging characteristic voltage. The acquisition method of the test charging characteristic voltage and the test discharging characteristic voltage can refer to the acquisition method of the charging characteristic voltage and the discharging characteristic voltage in the above embodiments, and the determination method of the test characteristic voltage can refer to the acquisition method of the current characteristic voltage in the above embodiments.

[0163] Exemplarily, as Figure 7 shown, V1 and V2 can be determined as the test charging characteristic voltages, and V3 can be determined as the test discharging characteristic voltage. The reason why only one characteristic peak is taken as the test discharging characteristic voltage in the discharging process is that the other peak value located at about 3.42V is not obvious, and the value will have a large error. The characteristic peak of the 4.2V negative electrode accounts for less than 20% of the total capacity, and there will be a large noise in the actual test process.

[0164] In the embodiments of the present application, the test characteristic voltage can be realized by formula (4):

[0165] (V1-V2)(V1-V3) formula (4);

[0166] Wherein, V1, V2 are test charging characteristic voltages, and V3 is a test discharging characteristic voltage.

[0167] The following Figures 8 to 14 explanation, the reason why the test characteristic voltage in the capacity test is determined by formula (4) in the embodiments of the present application.

[0168] Figure 8 The fitting relationship between V1 and the actual capacity of the test battery in the capacity test, Figure 9It is the fitting relationship between V2 and the actual capacity of the test battery in the capacity test. Figure 10 It is the fitting relationship between V3 and the actual capacity of the test battery in the capacity test. Figure 11 It is the fitting relationship between (V2-V1) (V2-V3) in the capacity test and the actual capacity of the test battery. Figure 12 It is the fitting relationship between (V3-V2) (V3-V1) and the actual capacity of the test battery in the capacity test. Figure 13 It is the fitting relationship between V1×V2×V3 in the capacity test and the actual capacity of the test battery. Figure 14 It is the fitting relationship between (V1-V2) (V1-V3) and the actual capacity of the test battery in the capacity test. Figures 8 to 13 It can be seen that Figures 8 to 13 There are obvious discrete points in the Figure 14 (i.e., the embodiment of the present application) has fewer discrete points. Therefore, the test characteristic voltage determined by formula (4) has a one-to-one correspondence with the actual capacity of the battery. Therefore, the capacity of the battery can be predicted more accurately based on the test characteristic voltage.

[0169] Step S503 : determining a preset corresponding relationship between the capacity decay rate of the battery to be tested and the characteristic voltage based on the multiple test characteristic voltages and the test capacity information corresponding to the test characteristic voltages.

[0170] In the embodiment of the present application, each test discharge characteristic voltage corresponds to a test capacity information. Therefore, through multiple test characteristic voltages and the test capacity information corresponding to the test characteristic voltages, a preset correspondence between the capacity attenuation rate of the battery to be tested and the characteristic voltage can be fitted.

[0171] In the embodiments of the present application, by conducting multiple tests on similar batteries under standard conditions and extracting the relationship between their characteristic voltage and capacity changes, a representative capacity decay model (i.e., a preset correspondence) can be constructed. This capacity decay model can then be used to quickly and accurately predict the current capacity of the battery. Furthermore, this capacity decay model can also be used to predict the capacity of similar batteries, improving the applicability of capacity prediction.

[0172] In some embodiments, the above step S503 can be implemented through steps S5031 to S5033:

[0173] Step S5031 , performing differential processing on a voltage sequence including a plurality of test characteristic voltages to obtain a plurality of test voltage difference values; the voltage sequence is obtained by sorting the plurality of test characteristic voltages according to capacity test time.

[0174] In the embodiment of the present application, the voltage variation between every two adjacent test characteristic voltages in the capacity test time among the multiple test characteristic voltages may be determined to obtain the test voltage difference.

[0175] For example, at time t1, the capacity test is performed on the test battery to obtain test characteristic voltage 1, at time t2, the capacity test is performed on the test battery to obtain test characteristic voltage 2, and at time t3, the capacity test is performed on the test battery to obtain test characteristic voltage 3. Then the voltage sequence is [test characteristic voltage 1, test characteristic voltage 2, test characteristic voltage 3]. The voltage sequence is differentially processed to obtain test voltage difference 1 = test characteristic voltage 2 - test characteristic voltage 1, and test voltage difference 2 = test characteristic voltage 3 - test characteristic voltage 2.

[0176] It is understandable that during normal use of the battery, the battery capacity will continue to decay, and correspondingly, the characteristic voltage will continue to shift. Therefore, it is necessary to determine the voltage change between the test characteristic voltages corresponding to different times to determine the degree of battery capacity decay.

[0177] For example, Figure 15 This is a schematic diagram of the relationship between the characteristic voltage of a battery and the battery usage time during the charging process provided by an embodiment of the present application. Figure 16 This is a schematic diagram showing the relationship between the characteristic voltage of a battery and the battery usage time during the discharge process provided by the embodiment of the present application. Figure 15 As shown, voltage 801 is the first test charge characteristic voltage corresponding to the battery when it leaves the factory (i.e., V2 in the above embodiment), voltage 802 is the first test charge characteristic voltage after the battery has been used for a period of time, voltage 803 is the second test charge characteristic voltage corresponding to the battery when it leaves the factory (i.e., V1 in the above embodiment), and voltage 804 is the second test charge characteristic voltage after the battery has been used for a period of time. It can be seen that the test charge characteristic voltage gradually increases with the use time of the battery. This is because as the battery ages, the energy required to embed lithium ions into carbon during charging becomes increasingly greater, so V1 and V2 will shift toward higher voltages. Among them, Figure 15 、 Figure 16 The curve graph is obtained by analyzing data for the ternary 6 series (i.e., Ni content accounts for 60% of the ternary material) battery cell with a rated capacity of 248Ah and the ternary 5 series (i.e., Ni content accounts for 50% of the ternary material) battery cell with a rated capacity of 117Ah.

[0178] like Figure 16As shown, voltage 901 is the test discharge characteristic voltage corresponding to the battery when it leaves the factory (i.e., V3 in the above embodiment), and voltage 902 is the test discharge characteristic voltage after the battery has been used for a period of time. It can be seen that the test discharge characteristic voltage gradually decreases with battery usage. This is because during discharge, the energy required for lithium ions to break away from the carbon decreases, so V3 shifts toward a lower voltage.

[0179] Step S5032: determining the test capacity attenuation rate of the test battery at different capacity test times based on the multiple test capacity information.

[0180] In the embodiment of the present application, the test capacity decay rate corresponding to every two test capacity information pieces that are adjacent in capacity test time among the multiple test capacity information pieces may be determined.

[0181] In the embodiment of the present application, the test capacity attenuation rate can be achieved by formula (5):

[0182] Formula (5).

[0183] Step S5033 , performing fitting processing on the multiple test capacity attenuation rates and the multiple test voltage differences to obtain a preset corresponding relationship.

[0184] In the embodiment of the present application, each capacity test time corresponds to a test data pair, which includes a test voltage difference and a test capacity attenuation rate. Therefore, the relationship between the capacity attenuation rate and the voltage difference can be fitted through multiple test data pairs. For example, Figure 17 As shown, the equation corresponding to the straight line 1001 is the above-mentioned preset corresponding relationship, which can be expressed by the above-mentioned formula (2).

[0185] In the embodiment of the present application, differential processing is performed to obtain the differential value of the test characteristic voltage. The test capacity decay rate is determined based on the test capacity information, and further fitting processing is performed to establish a preset corresponding relationship. Through the above method, the voltage and capacity change trends of the battery at different stages of use can be accurately captured, thereby efficiently predicting the capacity decay of the test battery, thereby achieving real-time monitoring of the health status of the test battery and risk warning.

[0186] In some embodiments, the test data also includes test current information; Figure 18 As shown, the above step S502 can be implemented through steps S1801 to S1803:

[0187] In step S1801, for each sampling time of each capacity test, the test voltage information corresponding to the sampling time, the test current information corresponding to the sampling time, the preset test current in the capacity test, and the polarization resistance of the test battery corresponding to the test voltage information are used to determine the normalization parameters of the test characteristic voltage.

[0188] The preset test current is obtained from the test current information in a preset manner.

[0189] In the embodiment of the present application, during each capacity test, the test current information is collected while collecting the test voltage information.

[0190] In the embodiment of the present application, the polarization resistance of the test battery under different test voltage information can be obtained by a voltage step method.

[0191] In the embodiment of the present application, the preset method may include at least one of the following: taking the minimum value, taking the maximum value, taking the median value, and taking the average value. In other words, the preset test current may be the minimum value, maximum value, median value, or average value of the multiple test current information.

[0192] In some embodiments, for each test characteristic voltage, the difference between the preset test current and the test current information corresponding to the test characteristic voltage can be determined first, and then the product of the difference and the polarization resistance corresponding to the test characteristic voltage can be determined as the normalized parameter of the test characteristic voltage.

[0193] In the embodiment of the present application, the normalization parameter can be determined by formula (6):

[0194] (II min ) R 极化 Formula (6);

[0195] Among them, I is the test current information, I min is the preset test current, R 极化 is the polarization resistance.

[0196] Step S1802 : performing normalization processing on the test voltage information based on the normalization parameter of the test characteristic voltage to obtain processed test voltage information.

[0197] In the embodiment of the present application, the difference between the test voltage information and the normalized parameter can be determined as the processed test voltage information.

[0198] In the embodiment of the present application, the normalization process of the test voltage information can be expressed by formula (7):

[0199] U 计算 =U 实际 -(II min ) R 极化Formula (7);

[0200] Among them, U 计算 is the processed test voltage information, U 实际 It is the test voltage information.

[0201] It is understandable that different capacity test processes may correspond to different test current information, so the test voltage information needs to be normalized according to the magnitude of the test current information.

[0202] Step S1803 : determining a test characteristic voltage of the test battery in each capacity test based on the processed test voltage information and test capacity information.

[0203] In an embodiment of the present application, a DQ / DV-V curve can be constructed based on the processed test voltage information and test capacity information, and then the test characteristic voltage of the test battery in each capacity test can be obtained on the DQ / DV-V curve.

[0204] In the embodiments of the present application, by introducing test current information and normalizing it with the polarization resistance of the test battery, the effects of charge and discharge current fluctuations on the voltage can be effectively eliminated. By introducing test current information and normalizing it with the polarization resistance of the test battery, the accuracy of the test voltage data can be improved, thereby obtaining a more reliable test characteristic voltage and, in turn, enabling a more accurate prediction of the capacity decay of the test battery.

[0205] The following describes the application of the battery capacity determination method provided in an embodiment of the present application in a practical scenario.

[0206] Step S11: fitting data in a laboratory environment.

[0207] In the embodiment of the present application, step S11 can be implemented by the following steps:

[0208] Step S111 : performing a capacity test on the lithium-ion battery every certain number of days under an internal test environment.

[0209] The charge and discharge data read during the capacity test only need to cover the 3.4V to 4V range of lithium-ion batteries. The parameters for the capacity test can be found in Table 1 above.

[0210] Step S112 , reading the test data of the lithium-ion battery, including the current I, voltage V, capacity Q, and test time t.

[0211] In the embodiment of the present application, since the actual charging and discharging current is not constant, it is necessary to calibrate the voltage according to the current. The calibration method can be implemented by the following steps:

[0212] Step S1121 , testing the polarization resistance of the battery cell at different voltages by a voltage step method.

[0213] Step S1122: normalize using the minimum current of the charging process.

[0214] The normalization formula can be found in the above formula (7).

[0215] Step S113: In the charge and discharge test phase, the voltage is differentiated by the charge / discharge capacity of the cell to obtain DQ / DV. A graph is drawn with DQ / DV as the Y-axis and voltage V as the X-axis.

[0216] Among them, the DQ / DV-V data of the capacity test process can be found in Figure 6 .

[0217] In step S114 , the test data is fitted by a spline interpolation method, and two voltage maxima V1 and V2 in the charging section between 3.5 and 3.8 V and a maximum voltage V3 in the discharging section are extracted.

[0218] The smoothness in the fitting process is 0.00001. Figure 7 .

[0219] In the embodiment of the present application, V1, V2, and V3 represent the negative electrode carbon materials in the charging and discharging stages of the lithium-ion battery (LiC6, LiC 12 、LiC 24 ) and the phase change of the positive electrode ternary material (nickel, cobalt and manganese) during the charge and discharge process. Among them, V1 corresponds to LiC 24 Converted to LiC 12 , V2 corresponds to LiC 12 Converted to LiC6, V3 corresponds to LiC6 converted to LiC 12 Due to the discharge process LiC 12 LiC in transformation 24 The resistance to conversion to LiC12 is small, so there is no obvious peak voltage.

[0220] In the embodiment of the present application, due to LiC6, LiC 12 、LiC 24 Due to the different properties, the actual offset of the cell characteristic voltage V1 is smaller (LiC 24 With LiC 12 The mutual conversion resistance is small), and the offset of V2 and V3 is large. Therefore, during the battery aging process, the difference between V1 and V2, V3 can represent the capacity attenuation of the battery.

[0221] In the embodiments of the present application, the reasons for the deviation of V1, V2, and V3 are as follows: during the continuous use of lithium-ion batteries, thermodynamic factors such as the gradual change in the structure of the battery cell electrode material and the loss of active materials (the change in material properties causes the change in its phase change voltage), and kinetic factors such as the thickening of the SEI film and the decomposition of the electrolyte (increased polarization, and the voltage deviation increases at the same current) jointly lead to the voltage deviation.

[0222] In the embodiment of the present application, the relationship between the peak value of the lithium-ion battery's charge and discharge and the difficulty of its phase change is positively correlated. The higher the peak value, the more difficult the phase change is. This is because the higher the peak value represents the higher the energy charged into the battery, and the greater the energy required to change a phase, that is, the more difficult the phase change is (that is, related to the proportion of battery capacity). In the embodiment of the present application, V1, V2, and V3 account for more than 50% of the total capacity of the battery cell, so the data error is relatively small.

[0223] In this embodiment, only one characteristic peak (V3) is used during the discharge phase because the other peak at around 3.42V is not obvious, which can lead to large errors in the value. The characteristic peak of the 4.2V negative electrode accounts for less than 20% of the total capacity, which will cause significant noise during actual testing.

[0224] In the embodiments of this application, during normal use of a lithium-ion battery, V1 and V2 will shift toward higher voltages (increase), while V3 will shift toward lower voltages (decrease). This is because, as the battery ages, the energy required to embed lithium ions into the carbon increases during charging, so V1 and V2 will shift toward higher voltages. During discharge, the energy required to release lithium ions from the carbon decreases, so V3 will shift toward lower voltages. Quantifying these shifts allows calculation of battery degradation.

[0225] Step S115 , subtracting and multiplying the three characteristic voltage combinations to obtain characteristic values.

[0226] In the embodiment of the present application, the determination of the characteristic value can refer to the above formula (4).

[0227] In some embodiments, the eigenvalue can also be realized by formula (8):

[0228] Y= Formula (8);

[0229] Among them, Y is the eigenvalue, and a, b, c, and x are all constants.

[0230] In the embodiment of the present application, the characteristic values ​​and actual capacities of multiple battery cells of the same product under different aging conditions can be recorded and fitted to obtain a, b, c, and x.

[0231] Step S116: fitting the difference between the capacity decay rate and the characteristic value.

[0232] In the embodiment of the application, the difference between the characteristic values in the two test processes of each battery is taken as the X axis, and the capacity attenuation rate is taken as the Y axis to plot a linear formula of the difference between the characteristic values and the capacity attenuation rate, and an actual formula of the capacity attenuation rate and the difference between the characteristic values is obtained by fitting. The actual formula can be seen from the formula (2) above.

[0233] In step S12, real environment calculation data is performed.

[0234] In the embodiment of the application, step S12 can be implemented by the following steps:

[0235] In step S121, capacity test is performed on the batteries in the battery pack to obtain actual test capacity, and the cell voltage, current and time in this process are read.

[0236] In step S122, the characteristic voltage (i.e., V1, V2 and V3) is determined based on the read data.

[0237] In step S123, the current characteristic value is determined based on the characteristic voltage, and the difference between the current characteristic value and the last characteristic value is determined.

[0238] In step S124, the difference between the current characteristic value and the last characteristic value is brought into Y=ax+b to obtain the capacity attenuation rate of the current battery.

[0239] In step S125, the capacity attenuation rate of the current battery is brought into Q i =Q i-1 (1+capacity attenuation rate) to obtain the current predicted capacity.

[0240] In the embodiment of the application, the actual capacity of the cell is accurately calculated, and it is determined whether the cell is in an abnormal capacity attenuation state, so that the capacity calculation has strong universality, and the process requirement for the battery test data is low.

[0241] Based on the foregoing embodiment, the embodiment of the application provides a battery capacity determination device, which includes units and modules included in the units, and can be implemented by a processor in a computer device. Of course, it can also be implemented by a specific logic circuit. In the implementation process, the processor can be a central processing unit (CPU), a micro processing unit (MPU), a digital signal processor (DSP) or a field programmable gate array (FPGA).

[0242] Figure 19A schematic diagram of the structure of a battery capacity determination device provided in an embodiment of the present application is shown in FIG. Figure 19 As shown, the battery capacity determination device 1900 includes: an acquisition module 1901, a first voltage determination module 1902, a second voltage determination module 1903, a third voltage determination module 1904, a voltage offset determination module 1905, and a capacity determination module 1906, wherein:

[0243] An acquisition module 1901 is configured to acquire first charging data and first discharging data of a battery to be tested, wherein the first charging data includes multiple charging voltage information and multiple charging capacity information that vary with time during a charging process; and the first discharging data includes multiple discharging voltage information and multiple discharging capacity information that vary with time during a discharging process.

[0244] A first voltage determination module 1902 is configured to determine, based on the plurality of charging voltage information and the plurality of charging capacity information, at least two charging characteristic voltages corresponding to phase changes of the positive and negative electrode materials of the battery under test during the charging process;

[0245] A second voltage determination module 1903 is configured to determine, based on the plurality of discharge voltage information and the plurality of discharge capacity information, at least one discharge characteristic voltage corresponding to a phase change of the positive and negative electrode materials of the battery under test during the discharge process;

[0246] a third voltage determining module 1904, configured to determine a current characteristic voltage for characterizing the capacity decay of the battery under test based on at least two charging characteristic voltages and at least one discharging characteristic voltage;

[0247] The voltage offset determination module 1905 is used to determine the voltage offset when the positive and negative electrode materials undergo phase change during the charge and discharge process based on the current characteristic voltage of the battery under test and the historical characteristic voltage of the battery under test at the previous moment;

[0248] The capacity determination module 1906 is configured to determine the current capacity of the battery under test based on the voltage offset when the positive and negative electrode materials undergo phase change during the charge and discharge process and the historical capacity of the battery under test at the previous moment.

[0249] In some embodiments, the above-mentioned third voltage determination module 1904 is also used to determine a first voltage deviation that characterizes the degree of change between the phase change resistances of different phase changes of the positive and negative electrode materials during the charging process based on at least two charging characteristic voltages; determine a second voltage deviation based on a target charging characteristic voltage among the at least two charging characteristic voltages, and at least one discharge characteristic voltage; the second voltage deviation is used to characterize the degree of change between the phase change resistance of the positive and negative electrode materials during the charging process, and the phase change resistance of the positive and negative electrode materials during the discharge process; determine the current characteristic voltage based on the first voltage deviation and the second voltage deviation.

[0250] In some embodiments, the first voltage determination module 1902 is further used to construct a first differential capacity voltage curve of the battery to be tested during the charging process based on multiple charging voltage information and multiple charging capacity information; the charging voltages corresponding to at least two peaks of the first differential capacity voltage curve are determined as at least two charging characteristic voltages; the second voltage determination module 1903 is used to construct a second differential capacity voltage curve of the battery to be tested during the discharging process based on multiple discharge voltage information and multiple discharge capacity information; the discharge voltage corresponding to at least one peak of the second differential capacity voltage curve is determined as at least one discharge characteristic voltage; wherein the voltage ranges corresponding to the multiple charging voltage information and the multiple discharging voltage information are smaller than the voltage range corresponding to the full charge and discharge of the battery to be tested.

[0251] In some embodiments, the first voltage determination module 1902 is configured to determine the charging voltage corresponding to the maximum peak of the first differential capacity voltage curve as the first charging characteristic voltage among the at least two charging characteristic voltages; and to determine the charging voltage corresponding to the peak adjacent to the maximum peak in the starting direction of the first differential capacity voltage curve as the second charging characteristic voltage among the at least two charging characteristic voltages.

[0252] In some embodiments, the capacity determination module 1906 is used to determine the capacity decay rate of the battery to be tested based on the voltage offset and a preset corresponding relationship; the preset corresponding relationship is the correspondence between the capacity decay rate and the voltage of the battery to be tested; based on the historical capacity and capacity decay rate of the battery to be tested, the current capacity of the battery to be tested is determined.

[0253] In some embodiments, the battery capacity determination device 1900 also includes: a test data acquisition module, a fourth voltage module, and a correspondence determination module; wherein the test data acquisition module is used to perform multiple capacity tests on a test battery whose battery type corresponds to the battery to be tested under a preset environment, and obtain multiple test data corresponding to each capacity test; the test data includes test voltage information and test capacity information; the fourth voltage module is used to determine the test characteristic voltage of the test battery in each capacity test based on the test voltage information and test capacity information corresponding to each capacity test; the correspondence determination module is used to determine the preset correspondence between the capacity attenuation rate and the characteristic voltage of the battery to be tested based on multiple test characteristic voltages and the test capacity information corresponding to the test characteristic voltage.

[0254] In some embodiments, a correspondence determination module is used to perform differential processing on a voltage sequence including multiple test characteristic voltages to obtain multiple test voltage difference values; the voltage sequence is obtained by sorting multiple test characteristic voltages according to capacity test time; based on multiple test capacity information, the test capacity attenuation rate of the test battery at different capacity test times is determined; multiple test capacity attenuation rates and multiple test voltage difference values ​​are fitted to obtain a preset correspondence relationship.

[0255] In some embodiments, the test data also includes test current information; a fourth voltage module is used to determine the normalization parameter of the test characteristic voltage for each sampling time of each capacity test based on the test current information corresponding to the sampling time, the preset test current in the capacity test, and the polarization resistance of the test battery corresponding to the test voltage information; the preset test current is obtained from the test current information in a preset manner; based on the normalization parameter of the test characteristic voltage, the test voltage information is normalized to obtain the processed test voltage information; based on the processed test voltage information and the test capacity information, the test characteristic voltage of the test battery in each capacity test is determined.

[0256] The description of the above device embodiment is similar to the description of the above method embodiment and has similar beneficial effects as the method embodiment. In some embodiments, the functions or modules included in the device provided in the embodiments of the present application can be used to perform the methods described in the above method embodiments. For technical details not disclosed in the device embodiments of the present application, please refer to the description of the method embodiments of the present application for understanding.

[0257] It should be noted that in the embodiments of the present application, if the above-mentioned data processing method is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiments of the present application, or the part that contributes to the relevant technology, can be embodied in the form of a software product. The software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the methods of each embodiment of the present application. The aforementioned storage medium includes various media that can store program code, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a magnetic disk, or an optical disk. In this way, the embodiments of the present application are not limited to any specific hardware, software, or firmware, or any combination of hardware, software, and firmware.

[0258] An embodiment of the present application provides a computer device including a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor executes the program, some or all of the steps in the above method are implemented.

[0259] The present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements some or all of the steps in the above method. The computer-readable storage medium may be transient or non-transient.

[0260] An embodiment of the present application provides a computer program, including computer-readable code. When the computer-readable code runs in a computer device, a processor in the computer device executes some or all of the steps for implementing the above method.

[0261] Embodiments of the present application provide a computer program product comprising a non-transitory computer-readable storage medium storing a computer program. When the computer program is read and executed by a computer, it implements some or all of the steps of the above-described method. The computer program product may be implemented in hardware, software, or a combination thereof. In some embodiments, the computer program product is embodied as a computer storage medium. In other embodiments, the computer program product is embodied as a software product, such as a software development kit (SDK).

[0262] It should be noted that the descriptions of the various embodiments above tend to emphasize the differences between the various embodiments, and their similarities or similarities can be referenced to each other. The descriptions of the above device, storage medium, computer program, and computer program product embodiments are similar to the descriptions of the above method embodiments and have similar beneficial effects as the method embodiments. For technical details not disclosed in the embodiments of the device, storage medium, computer program, and computer program product of this application, please refer to the description of the method embodiments of this application for understanding.

[0263] Figure 20 This is a hardware entity diagram of a battery capacity determination device in an embodiment of the present application, such as Figure 20 As shown, the hardware entity of the battery capacity determination device 2000 includes: a processor 2001, a communication interface 2002 and a memory 2003, wherein:

[0264] The processor 2001 generally controls the overall operation of the battery capacity determination device 2000 , and the overall operation may be to implement the battery capacity determination method provided in the embodiment of the present application.

[0265] The communication interface 2002 enables the computer device to communicate with other terminals or servers through the network.

[0266] Memory 2003 is configured to store instructions and applications executable by processor 2001. It can also cache data (e.g., image data, audio data, voice communication data, and video communication data) to be processed or processed by processor 2001 and various modules in battery capacity determination device 2000. This can be implemented using flash memory (FLASH) or random access memory (RAM). Data can be transmitted between processor 2001, communication interface 2002, and memory 2003 via bus 2004.

[0267] An embodiment of the present application provides a computer storage medium storing one or more programs, which can be executed by one or more processors to implement the steps of the battery capacity determination method of any of the above embodiments.

[0268] It should be noted that the description of the above storage medium and device embodiments is similar to the description of the above method embodiments and has similar beneficial effects as the method embodiments. For technical details not disclosed in the storage medium and device embodiments of this application, please refer to the description of the method embodiments of this application for understanding.

[0269] The processor may be at least one of an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a central processing unit (CPU), a controller, a microcontroller, and a microprocessor. It is understood that the electronic device that implements the functions of the processor may also be other electronic devices, which are not specifically limited in the embodiments of the present application.

[0270] The above-mentioned computer storage medium / memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic random access memory (FRAM), a flash memory (Flash Memory), a magnetic surface storage device, an optical disc, or a compact disc read-only memory (CD-ROM); it can also be various terminals that include one or any combination of the above-mentioned memories, such as mobile phones, computers, tablet devices, personal digital assistants, etc.

[0271] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned steps / processes does not mean the order of execution, and the execution order of each step / process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. The above-mentioned serial numbers of the embodiments of the present application are for description only and do not represent the advantages and disadvantages of the embodiments.

[0272] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0273] The above are only implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the protection scope of the present application.

Claims

1. A method for determining battery capacity, characterized in that: The battery capacity determination method comprises: Acquire first charging data and first discharging data of the battery to be tested, wherein the first charging data includes multiple charging voltage information and multiple charging capacity information that change with time during the charging process; and the first discharging data includes multiple discharging voltage information and multiple discharging capacity information that change with time during the discharging process; Determining, based on the multiple charging voltage information and the multiple charging capacity information, at least two charging characteristic voltages corresponding to phase changes of the positive and negative electrode materials of the battery to be tested during charging; Determining, based on the multiple discharge voltage information and the multiple discharge capacity information, at least one discharge characteristic voltage corresponding to a phase change of the positive and negative electrode materials of the battery to be tested during the discharge process; Determining a current characteristic voltage for characterizing a capacity attenuation condition of the battery to be tested based on the at least two charging characteristic voltages and the at least one discharging characteristic voltage; Determining, based on the current characteristic voltage of the battery to be tested and the historical characteristic voltage of the battery to be tested at a previous moment, a voltage offset when the positive and negative electrode materials undergo phase change during the charge and discharge process; The current capacity of the battery to be tested is determined based on the voltage offset when the positive and negative electrode materials undergo phase change during the charge and discharge process and the historical capacity of the battery to be tested at a previous moment.

2. The battery capacity determination method according to claim 1, wherein: The determining, based on the at least two charging characteristic voltages and the at least one discharging characteristic voltage, a current characteristic voltage for characterizing the capacity attenuation of the battery to be tested includes: Determining a first voltage deviation value representing a degree of change between phase change resistances of different phase changes of the positive and negative electrode materials during charging based on the at least two charging characteristic voltages; Determining a second voltage deviation based on a target charging characteristic voltage among the at least two charging characteristic voltages and the at least one discharge characteristic voltage; wherein the second voltage deviation is used to characterize a degree of change between a phase change resistance of the positive and negative electrode materials during a charging process and a phase change resistance of the positive and negative electrode materials during a discharging process; The current characteristic voltage is determined based on the first voltage deviation and the second voltage deviation.

3. The method for determining battery capacity according to claim 1, wherein: The determining, based on the multiple charging voltage information and the multiple charging capacity information, at least two charging characteristic voltages corresponding to phase changes of the positive and negative electrode materials of the battery to be tested during the charging process includes: constructing a first differential capacity-voltage curve of the battery to be tested during the charging process based on the multiple charging voltage information and the multiple charging capacity information; determining charging voltages corresponding to at least two peaks of the first differential capacity-voltage curve as the at least two charging characteristic voltages; The determining, based on the multiple discharge voltage information and the multiple discharge capacity information, at least one discharge characteristic voltage corresponding to a phase change of the positive and negative electrode materials of the battery to be tested during the discharge process includes: constructing a second differential capacity-voltage curve of the battery to be tested during the discharge process based on the multiple discharge voltage information and the multiple discharge capacity information; determining a discharge voltage corresponding to at least one peak of the second differential capacity-voltage curve as the at least one discharge characteristic voltage; The voltage ranges corresponding to the multiple charging voltage information and the multiple discharging voltage information are smaller than the voltage range corresponding to the complete charging and discharging of the battery to be tested.

4. The battery capacity determination method according to claim 3, characterized in that: The step of determining the charging voltages corresponding to the at least two peaks of the first differential capacity-voltage curve as the at least two charging characteristic voltages includes: determining a charging voltage corresponding to a maximum peak of the first differential capacity-voltage curve as a first charging characteristic voltage among the at least two charging characteristic voltages; The charging voltage corresponding to the peak in the starting direction of the first differential capacity-voltage curve and adjacent to the maximum peak is determined as the second charging characteristic voltage among the at least two charging characteristic voltages.

5. The battery capacity determination method according to claim 1, wherein: The determining the current capacity of the battery to be tested based on the voltage offset when the positive and negative electrode materials undergo phase change during the charge and discharge process and the historical capacity of the battery to be tested at the previous moment includes: Determining the capacity decay rate of the battery to be tested based on the voltage offset and a preset corresponding relationship; the preset corresponding relationship is a corresponding relationship between the capacity decay rate and the voltage of the battery to be tested; The current capacity of the battery to be tested is determined based on the historical capacity of the battery to be tested and the capacity decay rate.

6. The method for determining battery capacity according to any one of claims 1 to 5, characterized in that: The method further comprises: Under a preset environment, performing multiple capacity tests on a test battery of a battery type corresponding to the battery to be tested, and obtaining multiple test data corresponding to each capacity test; the test data includes test voltage information and test capacity information; Determining a test characteristic voltage of the test battery in each capacity test based on the test voltage information and the test capacity information corresponding to each capacity test; Based on the plurality of test characteristic voltages and the test capacity information corresponding to the test characteristic voltages, a preset corresponding relationship between the capacity decay rate of the battery to be tested and the characteristic voltage is determined.

7. The method for determining battery capacity according to claim 6, wherein: The determining the preset corresponding relationship based on the plurality of test characteristic voltages and the test capacity information corresponding to the test characteristic voltages includes: Performing differential processing on a voltage sequence including a plurality of the test characteristic voltages to obtain a plurality of test voltage difference values; the voltage sequence is obtained by sorting the plurality of the test characteristic voltages according to capacity test time; Determining a test capacity attenuation rate of the test battery at different capacity test times based on the plurality of test capacity information; Fitting processing is performed on the multiple test capacity attenuation rates and the multiple test voltage differences to obtain the preset corresponding relationship.

8. The method for determining battery capacity according to claim 6, wherein: The test data further includes test current information; and determining the test characteristic voltage of the test battery in each capacity test based on the test voltage information and the test capacity information corresponding to each capacity test includes: For each sampling time of each capacity test, determining a normalization parameter of the test characteristic voltage based on the test current information corresponding to the sampling time, a preset test current in the capacity test, and the polarization resistance of the test battery corresponding to the test voltage information; the preset test current is obtained from the test current information in a preset manner; performing normalization processing on the test voltage information based on the normalization parameter of the test characteristic voltage to obtain processed test voltage information; Based on the processed test voltage information and test capacity information, a test characteristic voltage of the test battery in each capacity test is determined.

9. A battery capacity determination device, characterized in that: The battery capacity determination device comprises: an acquisition module, configured to acquire first charging data and first discharging data of the battery to be tested, wherein the first charging data includes a plurality of charging voltage information and a plurality of charging capacity information that vary with time during a charging process; and the first discharging data includes a plurality of discharging voltage information and a plurality of discharging capacity information that vary with time during a discharging process; A first voltage determination module is configured to determine, based on the multiple charging voltage information and the multiple charging capacity information, at least two charging characteristic voltages corresponding to phase changes of the positive and negative electrode materials of the battery to be tested during charging; A second voltage determination module is configured to determine, based on the multiple discharge voltage information and the multiple discharge capacity information, at least one discharge characteristic voltage corresponding to a phase change of the positive and negative electrode materials of the battery to be tested during the discharge process; a third voltage determination module, configured to determine a current characteristic voltage for characterizing the capacity attenuation of the battery to be tested based on the at least two charging characteristic voltages and the at least one discharging characteristic voltage; A voltage offset determination module is used to determine the voltage offset of the positive and negative electrode materials when a phase change occurs during the charge and discharge process based on the current characteristic voltage of the battery to be tested and the historical characteristic voltage of the battery to be tested at a previous moment; The capacity determination module is used to determine the current capacity of the battery to be tested based on the voltage offset when the positive and negative electrode materials undergo phase change during the charge and discharge process and the historical capacity of the battery to be tested at the previous moment.

10. A battery capacity determination device, comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, characterized in that: When the processor executes the program, the steps of the method according to any one of claims 1 to 8 are implemented.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

12. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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