Battery self-discharge detection method and device

Abstract

The application provides a battery self-discharge detection method and device. The method controls a target battery to perform a first charge-discharge cycle in a preset SOC interval, and determines whether the target battery has a self-discharge abnormality based on a first SOC change rate of the target battery during the execution of the first charge-discharge cycle. The thickness change rate of the pole piece of the target battery in the first charge-discharge cycle is greater than or equal to a preset thickness change rate. Thus, by controlling the target battery to perform the first charge-discharge cycle, the dynamic change of the pole piece thickness of the target battery can be effectively strengthened, so that the conductive foreign matter in the target battery can penetrate the diaphragm in the target battery under the promotion of the dynamic change of the pole piece thickness, thereby effectively improving the detection probability of the battery with a potential self-discharge abnormality risk.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method and apparatus for detecting battery self-discharge. Background Technology

[0002] The self-discharge level of a lithium-ion battery is an important indicator of its performance. The higher the self-discharge level, the worse the safety performance of the lithium-ion battery. Therefore, in the production process of lithium-ion batteries, it is usually necessary to conduct self-discharge tests to screen out lithium-ion batteries with abnormal self-discharge.

[0003] Currently, self-discharge detection of lithium-ion batteries is usually based on factors such as the decay rate of open-circuit voltage. However, for lithium-ion batteries with a normal decay rate of open-circuit voltage but potential risk of abnormal self-discharge, the self-discharge abnormality cannot be detected based on the decay rate of open-circuit voltage, thus failing to guarantee the safe and reliable operation of lithium-ion batteries. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a battery self-discharge detection method and apparatus to solve the problem that existing technologies cannot detect lithium-ion batteries with potential self-discharge abnormalities.

[0005] To achieve the above technical objectives, the embodiments of this application provide the following technical solutions: Firstly, the embodiments of this specification provide a battery self-discharge detection method, including: The target battery is controlled to perform a first charge-discharge cycle within a preset SOC range, wherein the thickness change rate of the electrode of the target battery in the first charge-discharge cycle is greater than or equal to a preset thickness change rate. Based on the first SOC change rate of the target battery during the first charge-discharge cycle, it is determined whether the target battery has a self-discharge abnormality.

[0006] In one implementation, determining whether the target battery has a self-discharge abnormality based on the first SOC change rate of the target battery during the first charge-discharge cycle includes: Based on the relationship between the first SOC change rate and the preset SOC change rate during the charging phase of the first charge-discharge cycle, it is determined whether the target battery has a self-discharge abnormality.

[0007] In one embodiment, the preset SOC range includes 70% to 90%.

[0008] In one embodiment, controlling the target battery to perform a first charge-discharge cycle within a preset SOC range includes: The target battery is charged to the upper limit of the preset SOC range by constant current charging, and discharged to the lower limit of the preset SOC range by constant current discharging.

[0009] In one embodiment, controlling the target battery to perform a first charge-discharge cycle within a preset SOC range further includes: When the target battery is charged to the upper limit of the preset SOC range, the target battery is controlled to be left idle for a first preset time; and when the target battery is discharged to the lower limit of the preset SOC range, the target battery is controlled to be left idle for a second preset time.

[0010] In one implementation, it further includes: If it is determined that the target battery does not have any self-discharge abnormalities, the target battery is controlled to perform a second charge-discharge cycle based on a preset capacity grading strategy.

[0011] In one embodiment, the SOC range corresponding to the second charge-discharge cycle includes the preset SOC range; and further includes: Based on the second SOC change rate of the target battery during the second charge-discharge cycle, it is determined whether the target battery has a self-discharge abnormality.

[0012] In one implementation, it further includes: After the second charge-discharge cycle is completed, the decay rate of the open-circuit voltage of the target battery under preset conditions is obtained; Based on the decay rate of the open-circuit voltage, it is determined whether the target battery has a self-discharge abnormality.

[0013] Secondly, embodiments of this specification provide a battery self-discharge detection device, comprising: The first processing module is used to control the target battery to perform a first charge-discharge cycle within a preset SOC range, wherein the thickness change rate of the electrode of the target battery in the first charge-discharge cycle is greater than or equal to a preset thickness change rate. The second processing module is used to determine whether the target battery has a self-discharge abnormality based on the first SOC change rate of the target battery during the first charge-discharge cycle.

[0014] Thirdly, embodiments of this specification provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the battery self-discharge detection method as described in any of the preceding claims.

[0015] Fourthly, embodiments of this specification provide a computer program product or a computer program, the computer program product including a computer program stored in a computer-readable storage medium; the processor of the computer device reads the computer program from the computer-readable storage medium, and when the processor executes the computer program, it implements the battery self-discharge detection method as described in any of the preceding claims.

[0016] As can be seen from the above technical solutions, the embodiments of this application provide a battery self-discharge detection method and apparatus. By controlling the target battery to perform a first charge-discharge cycle within a preset SOC range, and based on the first SOC change rate of the target battery during the first charge-discharge cycle, it is determined whether the target battery has a self-discharge abnormality. The thickness change rate of the target battery's electrode in the first charge-discharge cycle is greater than or equal to a preset thickness change rate. Therefore, by controlling the target battery to perform the first charge-discharge cycle, the dynamic change of the target battery's electrode thickness can be effectively enhanced, thereby enabling conductive foreign objects inside the target battery to penetrate the separator in the target battery under the promoting effect of the dynamic change of electrode thickness, thus effectively increasing the detection probability of batteries with potential self-discharge abnormality risks. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of a battery self-discharge detection method provided in one embodiment of this application.

[0019] Figure 2 This is a schematic diagram illustrating the variation trend of negative electrode thickness with SOC during the charging process of a lithium-ion battery, as provided in one embodiment of this application.

[0020] Figure 3 This is a schematic diagram of a battery self-discharge detection device provided in one embodiment of this application. Detailed Implementation

[0021] Unless otherwise defined, the technical or scientific terms used in the embodiments of this specification shall have the ordinary meaning understood by one of ordinary skill in the art to which this specification pertains. The terms "first," "second," and similar terms used in the embodiments of this specification do not indicate any order, quantity, or importance, but are merely used to avoid confusion of constituent elements.

[0022] Unless the context otherwise requires, throughout this specification, "a plurality of" means "at least two," and "including" is interpreted as open-ended or encompassing, that is, "including, but not limited to." In the description of this specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this specification. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example.

[0023] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this specification.

[0024] Overview As described in the background section, the self-discharge level of a lithium-ion battery is an important indicator of its performance. The higher the self-discharge level, the worse the safety performance of the lithium-ion battery. Therefore, in the production process of lithium-ion batteries, it is usually necessary to conduct self-discharge testing to screen out lithium-ion batteries with abnormal self-discharge.

[0025] Currently, self-discharge testing of lithium-ion batteries is typically based on factors such as the rate of open-circuit voltage decay. However, a significant increase in the rate of open-circuit voltage decay only occurs when conductive foreign matter (such as metal particles, dust, or burrs) physically penetrates the separator, or when the separator itself has defects (such as pores or damage), creating a tiny conductive path between the positive and negative electrodes—that is, when a physical short circuit forms inside the lithium-ion battery.

[0026] If a conductive foreign object inside a lithium-ion battery has not pierced the separator, or has only contacted one electrode but has not penetrated to the other electrode, the rate of decay of its open-circuit voltage will appear normal. Thus, during the self-discharge detection process, the self-discharge detection result will be normal, but there is a high risk of abnormal self-discharge, which means that the safe and reliable operation of the lithium-ion battery cannot be guaranteed.

[0027] To address the problem that traditional methods cannot detect lithium-ion batteries with potential self-discharge risks, this application's technical solution controls the target battery to perform a first charge-discharge cycle within a preset SOC range. Based on the first SOC change rate during the first charge-discharge cycle, the presence of self-discharge anomalies in the target battery is determined. Specifically, the thickness change rate of the target battery's electrodes during the first charge-discharge cycle is greater than or equal to a preset thickness change rate. Therefore, by controlling the target battery to perform the first charge-discharge cycle, the dynamic change in the electrode thickness of the target battery can be effectively enhanced. This allows conductive foreign matter inside the target battery to penetrate the separator under the promoting effect of the dynamic change in electrode thickness, thereby effectively increasing the detection probability of batteries with potential self-discharge risks.

[0028] Based on the above inventive concept, the battery self-discharge detection method and apparatus provided in the embodiments of this specification will be described exemplarily below.

[0029] Exemplary methods This specification provides a method for detecting battery self-discharge, such as... Figure 1 As shown, the method includes: S101. Control the target battery to perform a first charge-discharge cycle within a preset SOC range, wherein the thickness change rate of the electrode of the target battery in the first charge-discharge cycle is greater than or equal to a preset thickness change rate.

[0030] Specifically, the target battery is the battery that is to be tested for self-discharge at the current moment. The target battery can be a lithium-ion battery, including a positive electrode, a negative electrode, and a separator for separating the positive and negative electrodes.

[0031] The preset SOC (State of Charge) range can be determined based on the rate of change of the electrode thickness of the lithium-ion battery during charging and discharging. This rate of change can be the thickness change rate of either the positive or negative electrode. Preferably, it is the thickness change rate of the negative electrode. During the charging and discharging process, the insertion and extraction of lithium ions cause the crystal structure of the electrode active material to expand or contract. The differences in material structure and lithium insertion capacity between the positive and negative electrodes result in a much greater rate of change of thickness for the negative electrode than for the positive electrode.

[0032] During the charging and discharging of lithium ions within the preset SOC range, the thickness change rate of the lithium ion battery electrode can be greater than or equal to the preset thickness change rate, which can be set according to actual needs.

[0033] In practice, the target battery can be controlled to perform at least one first charge-discharge cycle within a preset SOC range. The first charge-discharge cycle can include a charging phase and a discharging phase. During the charging phase, the cutoff SOC of the target battery can be less than or equal to the upper limit of the preset SOC range, and during the discharging phase, the cutoff SOC of the target battery can be greater than or equal to the lower limit of the preset SOC range. Therefore, during the first charge-discharge cycle of the target battery, the thickness change rate of its electrode can be greater than or equal to the preset thickness change rate in both the charging and discharging phases.

[0034] Therefore, by controlling the target battery to perform the first charge-discharge cycle within a preset SOC range, the dynamic change in the electrode thickness of the target battery can be enhanced. This allows the mechanical force generated by the electrode expansion to push conductive foreign objects inside the target battery to pierce the separator, thereby effectively increasing the detection probability of batteries with potential self-discharge abnormalities. Simultaneously, during the first charge-discharge cycle of the target battery, the electrolyte circulation can remove part of the protective liquid film from the separator, and the temperature fluctuations of the target battery combined with the changes in electrode thickness lower the separator's protection threshold, making it easier for conductive foreign objects inside the target battery to pierce the separator, further increasing the detection probability of batteries with potential self-discharge abnormalities.

[0035] S102. Based on the first SOC change rate of the target battery during the first charge-discharge cycle, determine whether the target battery has a self-discharge abnormality.

[0036] Specifically, during the first charge-discharge cycle of the target battery, the SOC change rate of the target battery can also be obtained and used as the first SOC change rate of the target battery. At any moment during the first charge-discharge cycle, the SOC change rate of the target battery at that moment can be the ratio of the SOC change at that moment to the SOC at the previous moment, and the SOC change at that moment can be the difference between the SOC at that moment and the SOC at the previous moment.

[0037] Specifically, the presence of self-discharge abnormality in the target battery can be determined based on the first SOC change rate during the first charge-discharge cycle. Thus, based on the influence of the target battery's self-discharge on the SOC change rate during the charge-discharge process, it is possible to quickly and accurately determine whether the target battery has a self-discharge abnormality.

[0038] Therefore, the embodiment of this application can effectively enhance the dynamic change of the electrode thickness of the target battery by controlling the target battery to perform the first charge-discharge cycle within a preset SOC range. This allows conductive foreign objects inside the target battery to penetrate the separator in the target battery under the promotion of the dynamic change of electrode thickness, thereby effectively increasing the detection probability of batteries with potential self-discharge abnormality risk.

[0039] In one feasible implementation, determining whether the target battery has a self-discharge abnormality based on the first SOC change rate of the target battery during the first charge-discharge cycle includes: Based on the relationship between the first SOC change rate and the preset SOC change rate during the charging phase of the first charge-discharge cycle, it is determined whether the target battery has a self-discharge abnormality.

[0040] Specifically, during the process of controlling the target battery to perform any first charge-discharge cycle, the first SOC change rate of the target battery can be obtained during the charging phase, and the self-discharge abnormality of the target battery can be determined based on the relationship between the first SOC change rate of the target battery during the charging phase and the preset SOC change rate.

[0041] The preset SOC change rate can be calibrated based on the SOC change rate of lithium-ion batteries of the same model and / or batch during charging and discharging within a preset SOC range under conditions of no self-discharge abnormalities. In practice, the preset SOC change rate can be calibrated based on historical operating data of lithium-ion batteries of the same model and / or batch, or it can be calibrated through experiments. The specific setting can be determined according to actual needs.

[0042] The preset SOC change rate can be a fixed value, or it can be divided into multiple SOC sub-intervals based on the SOC change rate changes of lithium-ion batteries of the same model and / or batch during the charging stage, and the SOC change rate threshold corresponding to each SOC sub-interval can be marked. That is, the preset SOC change rate includes the SOC change rate threshold corresponding to each SOC sub-interval.

[0043] With a preset SOC change rate of a fixed value, the process of determining whether the target battery has a self-discharge abnormality is based on the relationship between the first SOC change rate of the target battery during the charging phase and the preset SOC change rate. If the first SOC change rate of the target battery during the charging phase is greater than or equal to the preset SOC change rate, it indicates that the SOC of the target battery can rise at a normal rate during the charging phase, and it can be determined that the target battery does not have a self-discharge abnormality. If the first SOC change rate of the target battery during the charging phase is less than the preset SOC change rate, it indicates that the SOC rise rate of the target battery is slower due to self-discharge during the charging phase, and it can be determined that the target battery has a self-discharge abnormality. This allows for real-time detection of whether a conductive path is formed inside the target battery, leading to a self-discharge abnormality, during the dynamic change of the electrode thickness of the target battery. This enables rapid and effective detection of self-discharge abnormalities in the target battery, increasing the detection probability of batteries with potential self-discharge abnormality risks.

[0044] Furthermore, when the preset SOC change rate includes a threshold for the SOC change rate corresponding to each SOC sub-interval, in determining whether the target battery has a self-discharge abnormality based on the relationship between the first SOC change rate of the target battery during the charging phase and the preset SOC change rate, the first target sub-interval can be determined from multiple SOC sub-intervals based on the current SOC of the target battery. During the charging phase of the target battery, the presence of a self-discharge abnormality is determined based on the relationship between the first SOC change rate of the target battery at the current moment and the SOC change rate threshold corresponding to the first target sub-interval. If the first SOC change rate of the target battery at the current moment is greater than or equal to the SOC change rate threshold corresponding to the first target sub-interval, it indicates that the SOC of the target battery can rise at a normal rate during the charging phase, and it can be determined that the target battery does not have a self-discharge abnormality. If the first SOC change rate of the target battery at the current moment is less than the SOC change rate threshold corresponding to the first target sub-interval, it indicates that the SOC rise rate of the target battery is slow due to self-discharge during the charging phase, and it can be determined that the target battery has a self-discharge abnormality. This further improves the accuracy of the determination result of whether the target battery has a self-discharge abnormality.

[0045] In one feasible implementation, the preset SOC range includes 70% to 90%.

[0046] Specifically, the preset SOC range can include 70% to 90%, that is, the lower limit of the preset SOC range can be 70%, and the upper limit of the preset SOC range can be 90%.

[0047] In practice, the preset SOC range can be calibrated based on historical operating data of lithium-ion batteries of the same model and / or batch, or under test conditions. For example, the electrode thickness change rate of multiple lithium-ion batteries of the same model and / or batch during charge-discharge cycles within the full SOC range can be obtained, and the preset SOC range can be calibrated based on the electrode thickness change rate of each lithium-ion battery.

[0048] Taking the thickness change rate of the negative electrode sheet during the charging process of a lithium-ion battery as an example, when the State of Charge (SOC) is greater than 90% and less than 70%, the thickness change of the negative electrode sheet tends to be stable. However, when the SOC is between 70% and 90%, the thickness change of the negative electrode sheet is relatively rapid. Specifically, this can be seen as follows... Figure 2 As shown, it should be noted that Figure 2 The thickness variation trend of the negative electrode sheet of lithium-ion battery is not shown when the SOC is less than 60%.

[0049] Therefore, by setting 70%~90% as the preset SOC range, the dynamic change of the electrode thickness of the target battery can be enhanced to the greatest extent during the first charge-discharge cycle controlled within the preset SOC range. This allows conductive foreign objects inside the target battery to penetrate the separator in the target battery under the promotion of the dynamic change of electrode thickness, thereby effectively increasing the detection probability of batteries with potential self-discharge abnormality risk.

[0050] In one feasible implementation, controlling the target battery within a preset SOC range to perform a first charge-discharge cycle includes: The target battery is charged to the upper limit of the preset SOC range by constant current charging, and discharged to the lower limit of the preset SOC range by constant current discharging.

[0051] Specifically, during the process of controlling the target battery to perform the first charge-discharge cycle within the preset SOC range, in the charging phase, the target battery can be charged to the upper limit of the preset SOC range by constant current charging. At the same time, in the discharging phase, the target battery can be discharged to the lower limit of the preset SOC range by constant current discharging. The charging and discharging efficiency and charging and discharging safety are high, and the charging and discharging control logic is relatively simple and easy to implement. Thus, while improving the self-discharge detection efficiency of the target battery, it can further improve the detection probability of batteries with potential self-discharge abnormality risks.

[0052] The charging current of constant current charging and the discharging current of constant current discharging can be set according to actual needs. For example, it can be set to 1C, which can effectively improve the self-discharge detection efficiency of the target battery. It is understandable that when the lithium-ion battery meets the fast charging conditions, the charging current of constant current charging and the discharging current of constant current discharging can be greater than 1C to further improve the self-discharge detection efficiency of the target battery.

[0053] In one feasible implementation, controlling the target battery to perform a first charge-discharge cycle within a preset SOC range further includes: When the target battery is charged to the upper limit of the preset SOC range, the target battery is controlled to be left idle for a first preset time; and when the target battery is discharged to the lower limit of the preset SOC range, the target battery is controlled to be left idle for a second preset time.

[0054] Specifically, during the process of controlling the target battery to perform the first charge-discharge cycle within the preset SOC range, the target battery can be left idle for a certain period of time between the charging and discharging phases. That is, during the idle period, the target battery is neither charged nor discharged.

[0055] Specifically, when controlling the target battery to charge to the upper limit of the preset SOC range, the target battery can be paused for a first preset time. This first preset time can be set according to actual needs to avoid the polarization of the target battery during the charging phase affecting the accuracy of SOC detection in the next discharging phase. Simultaneously, by controlling the pause time after the charging phase ends, the cycle stress of the target battery can be buffered, and heat dissipation and cooling can be performed, thereby effectively reducing the impact on the target battery's performance during self-discharge detection.

[0056] Furthermore, when controlling the target battery to discharge to the lower limit of the preset SOC range, the target battery can be left idle for a second preset duration. This second preset duration can be the same as or different from the first preset duration, depending on actual needs. This avoids the polarization of the target battery during the discharge phase affecting the accuracy of SOC detection in the next charging phase, thereby improving the accuracy of the self-discharge anomaly detection results. Simultaneously, by controlling the second preset duration after the discharge phase ends, the cycling pressure of the target battery can be buffered, and heat dissipation and cooling can be performed, effectively reducing the impact on the target battery's performance during self-discharge detection.

[0057] Taking the execution of the first charge-discharge cycle with the initial SOC of the target battery at 60% as an example, the steps for executing the first charge-discharge cycle can be shown in Table 1.

[0058] Table 1 In one feasible implementation, it also includes: If it is determined that the target battery does not have any self-discharge abnormalities, the target battery is controlled to perform a second charge-discharge cycle based on a preset capacity grading strategy.

[0059] Specifically, if the target battery is found to have a self-discharge abnormality during the execution of the first charge-discharge cycle, the execution of the first charge-discharge cycle can be stopped, and subsequent abnormal battery isolation and other procedures can be performed to avoid the impact of the battery with self-discharge abnormality on the overall working performance of the battery system.

[0060] Furthermore, if no self-discharge abnormality is detected in the target battery at the end of the first charge-discharge cycle, a second charge-discharge cycle can be controlled based on a preset capacity grading strategy. This preset strategy can be set according to actual needs. For example, the target battery can be controlled to perform the second charge-discharge cycle within the full SOC range (0%~100%), and the actual discharge capacity of the target battery during the discharge phase of the second charge-discharge cycle can be used as the nominal capacity of the target battery. Alternatively, the target battery can be controlled to perform the second charge-discharge cycle within a target SOC range, which is a portion of the full SOC range, for example, 0%~20%, to predict the nominal capacity of the target battery based on the actual discharge capacity of the target battery during the discharge phase of the second charge-discharge cycle.

[0061] After determining the nominal capacity of the target battery, the batteries can be grouped according to their nominal capacity to ensure the consistency of capacity among the batteries in the same group.

[0062] By controlling the target battery to perform a first charge-discharge cycle within a preset SOC range before performing capacity grading, batteries with potential self-discharge abnormalities can be screened out, thereby effectively improving the efficiency of battery capacity grading.

[0063] In one feasible implementation, the SOC range corresponding to the second charge-discharge cycle includes the preset SOC range; and further includes: Based on the second SOC change rate of the target battery during the second charge-discharge cycle, it is determined whether the target battery has a self-discharge abnormality.

[0064] Specifically, the SOC range corresponding to the second charge-discharge cycle can be the SOC range formed by the cutoff SOC of the charging phase and the cutoff SOC of the discharging phase during the execution of the second charge-discharge cycle. That is, the cutoff SOC of the charging phase can be used as the upper limit of the SOC range corresponding to the second charge-discharge cycle, and the cutoff SOC of the discharging phase can be used as the lower limit of the SOC range corresponding to the second charge-discharge cycle.

[0065] The SOC range corresponding to the second charge-discharge cycle can include a preset SOC range. That is, the lower limit of the SOC range corresponding to the second charge-discharge cycle can be less than or equal to the lower limit of the preset SOC range, while the upper limit of the SOC range corresponding to the second charge-discharge cycle can be greater than or equal to the upper limit of the preset SOC range. This allows for enhanced dynamic changes in the electrode thickness of the target battery during the capacity grading process, further increasing the detection probability of batteries with potential self-discharge abnormalities.

[0066] In practice, during the capacity testing of the target battery, the presence of self-discharge abnormalities can be determined based on the second SOC change rate of the target battery during the second charge-discharge cycle. For example, during the charging phase of the second charge-discharge cycle, the presence of self-discharge abnormalities can be determined based on the relationship between the second SOC change rate and the preset SOC change rate within the preset SOC range.

[0067] For example, when the preset SOC change rate is a fixed value, the process of determining whether the target battery has a self-discharge abnormality is based on the relationship between the second SOC change rate of the target battery within the preset SOC range and the preset SOC change rate. If the second SOC change rate of the target battery within the preset SOC range is greater than or equal to the preset SOC change rate, it indicates that the SOC of the target battery can rise at a normal rate during the charging phase. In this case, it can be determined that the target battery does not have a self-discharge abnormality. If the second SOC change rate of the target battery within the preset SOC range is less than the preset SOC change rate, it indicates that the SOC rise rate of the target battery is slow due to self-discharge during the charging phase. In this case, it can be determined that the target battery has a self-discharge abnormality. Thus, during the capacity grading process of the target battery, it is possible to detect in real time whether a conductive path is formed inside the target battery, causing the target battery to have a self-discharge abnormality, further improving the detection probability of batteries with potential self-discharge abnormality risks.

[0068] Furthermore, when the preset SOC change rate includes a threshold for the SOC change rate corresponding to each SOC sub-interval, in determining whether the target battery has a self-discharge abnormality based on the relationship between the second SOC change rate of the target battery within the preset SOC interval and the preset SOC change rate, a second target sub-interval can be determined from multiple SOC sub-intervals based on the current SOC of the target battery. The presence of a self-discharge abnormality is then determined based on the relationship between the second SOC change rate of the target battery within the preset SOC interval and the threshold for the SOC change rate corresponding to the second target sub-interval. Specifically, if the second SOC change rate of the target battery at the current moment is greater than or equal to the threshold for the SOC change rate corresponding to the second target sub-interval, it indicates that the SOC of the target battery is rising at a normal rate during the charging phase, and thus, it can be determined that the target battery does not have a self-discharge abnormality. If the second SOC change rate of the target battery at the current moment is less than the threshold for the SOC change rate corresponding to the second target sub-interval, it indicates that the SOC rise rate of the target battery is slow due to self-discharge during the charging phase, and thus, it can be determined that the target battery has a self-discharge abnormality. This further improves the accuracy of the determination of whether the target battery has a self-discharge abnormality.

[0069] Optionally, taking the preset capacity grading strategy as an example to control the target battery to perform the second charge-discharge cycle within the full SOC range, the steps for performing the second charge-discharge cycle can be as shown in Table 2.

[0070] Table 2 In one feasible implementation, it also includes: After the second charge-discharge cycle is completed, the decay rate of the open-circuit voltage of the target battery under preset conditions is obtained; Based on the decay rate of the open-circuit voltage, it is determined whether the target battery has a self-discharge abnormality.

[0071] Specifically, if the target battery is found to have a self-discharge abnormality during the second charge-discharge cycle (i.e., capacity testing), the second charge-discharge cycle can be stopped, and subsequent abnormal battery isolation and other procedures can be performed to avoid the impact of the battery with self-discharge abnormality on the overall working performance of the battery system.

[0072] In addition, if no self-discharge abnormality is detected in the target battery at the end of the second charge-discharge cycle, the decay rate of the open-circuit voltage of the target battery under preset conditions can be obtained, and the presence of self-discharge abnormality in the target battery can be determined based on the decay rate of the open-circuit voltage of the target battery under preset conditions, thereby further improving the detection rate of batteries with self-discharge abnormalities.

[0073] The preset conditions can be set according to actual needs. For example, it can include placing the target battery in a preset test environment for a third target duration (e.g., several hours or several days). The preset test environment can be a constant temperature environment, such as 25±1℃.

[0074] During the process of placing the target battery in a preset test environment, the open-circuit voltage of the target battery can be sampled at preset time intervals. For any sampling time, the ratio of the open-circuit voltage decay at that sampling time to the open-circuit voltage at the initial resting time can be used as the decay rate of the open-circuit voltage at that sampling time. The open-circuit voltage decay at that sampling time can be the difference between the open-circuit voltage at the initial resting time and the open-circuit voltage at that sampling time.

[0075] Specifically, the presence of self-discharge anomalies in the target battery can be determined based on the relationship between the decay rate of the open-circuit voltage at each sampling time and a target decay rate threshold. For example, for any sampling time, if the decay rate of the open-circuit voltage at that sampling time is greater than the target decay rate threshold, the target battery is determined to have a self-discharge anomaly; if the decay rate is less than or equal to the target decay rate threshold, the target battery is determined not to have a self-discharge anomaly. The target decay rate threshold can be a fixed preset value, or it can be determined based on the resting time of the target battery at that sampling time and the correspondence between the resting time and the decay rate threshold, and used as the target decay rate threshold, thereby accurately determining whether the target battery has a self-discharge anomaly.

[0076] Exemplary devices and equipment refer to Figure 3 This specification also provides a battery self-discharge detection device, comprising: The first processing module 301 is used to control the target battery to perform a first charge-discharge cycle within a preset SOC range, wherein the thickness change rate of the electrode of the target battery in the first charge-discharge cycle is greater than or equal to a preset thickness change rate. The second processing module 302 is used to determine whether the target battery has a self-discharge abnormality based on the first SOC change rate of the target battery during the first charge-discharge cycle.

[0077] In one feasible implementation, the second processing module 302 is specifically used for: Based on the relationship between the first SOC change rate and the preset SOC change rate during the charging phase of the first charge-discharge cycle, it is determined whether the target battery has a self-discharge abnormality.

[0078] In one feasible implementation, the preset SOC range includes 70% to 90%.

[0079] In one feasible implementation, the first processing module 301 is specifically used for: The target battery is charged to the upper limit of the preset SOC range by constant current charging, and discharged to the lower limit of the preset SOC range by constant current discharging.

[0080] In one feasible implementation, the first processing module 301 is further configured to: When the target battery is charged to the upper limit of the preset SOC range, the target battery is controlled to be left idle for a first preset time; and when the target battery is discharged to the lower limit of the preset SOC range, the target battery is controlled to be left idle for a second preset time.

[0081] In one feasible implementation, a third processing module is further included, the third processing module being used for: If it is determined that the target battery does not have any self-discharge abnormalities, the target battery is controlled to perform a second charge-discharge cycle based on a preset capacity grading strategy.

[0082] In one feasible implementation, the SOC range corresponding to the second charge-discharge cycle includes the preset SOC range; the third processing module is further configured to: Based on the second SOC change rate of the target battery during the second charge-discharge cycle, it is determined whether the target battery has a self-discharge abnormality.

[0083] In one feasible implementation, a fourth processing module is further included, the fourth processing module being used for: After the second charge-discharge cycle is completed, the decay rate of the open-circuit voltage of the target battery under preset conditions is obtained; Based on the decay rate of the open-circuit voltage, it is determined whether the target battery has a self-discharge abnormality.

[0084] The battery self-discharge detection device provided in this embodiment belongs to the same concept as the battery self-discharge detection method provided in the above embodiments of this application. It can execute the battery self-discharge detection method provided in any of the above embodiments of this application and has the corresponding functional modules and beneficial effects for executing the battery self-discharge detection method. Technical details not described in detail in this embodiment can be found in the specific processing content of the battery self-discharge detection method provided in the above embodiments of this application, and will not be repeated here.

[0085] Exemplary computer program products and storage media In addition to the methods and devices described above, the battery self-discharge detection method provided in the embodiments of this specification can also be a computer program product, which includes computer program instructions that, when executed by a processor, cause the processor to perform the steps in the battery self-discharge detection method according to various embodiments of this specification as described in the "Exemplary Methods" section above.

[0086] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of this specification. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as the "C" language or similar programming languages.

[0087] Furthermore, embodiments of this specification also provide a computer-readable storage medium having a computer program stored thereon, the computer program being executed by a processor of the steps in the battery self-discharge detection method according to various embodiments of this specification as described in the "Exemplary Methods" section above.

[0088] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this specification can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0089] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The embodiments described above are merely illustrative of several implementation methods outlined in this specification. While the descriptions are specific and detailed, they should not be construed as limiting the scope of the solutions provided in this specification. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this specification, and these all fall within the scope of protection of this specification. Therefore, the scope of protection for this patent should be determined by the appended claims.

Claims

1. A method for detecting battery self-discharge, characterized in that, include: The target battery is controlled to perform a first charge-discharge cycle within a preset SOC range, wherein the thickness change rate of the electrode of the target battery in the first charge-discharge cycle is greater than or equal to a preset thickness change rate. Based on the first SOC change rate of the target battery during the first charge-discharge cycle, it is determined whether the target battery has a self-discharge abnormality.

2. The method according to claim 1, characterized in that, Based on the first SOC change rate of the target battery during the first charge-discharge cycle, determine whether the target battery has a self-discharge abnormality, including: Based on the relationship between the first SOC change rate and the preset SOC change rate during the charging phase of the first charge-discharge cycle, it is determined whether the target battery has a self-discharge abnormality.

3. The method according to claim 1, characterized in that, The preset SOC range includes 70% to 90%.

4. The method according to claim 1, characterized in that, Controlling the target battery within a preset SOC range to perform the first charge-discharge cycle includes: The target battery is charged to the upper limit of the preset SOC range by constant current charging, and discharged to the lower limit of the preset SOC range by constant current discharging.

5. The method according to claim 4, characterized in that, Controlling the target battery to perform the first charge-discharge cycle within a preset SOC range also includes: When the target battery is charged to the upper limit of the preset SOC range, the target battery is controlled to be left idle for a first preset time; and when the target battery is discharged to the lower limit of the preset SOC range, the target battery is controlled to be left idle for a second preset time.

6. The method according to any one of claims 1 to 5, characterized in that, Also includes: If it is determined that the target battery does not have any self-discharge abnormalities, the target battery is controlled to perform a second charge-discharge cycle based on a preset capacity grading strategy.

7. The method according to claim 6, characterized in that, The SOC range corresponding to the second charge-discharge cycle includes the preset SOC range; it also includes: Based on the second SOC change rate of the target battery during the second charge-discharge cycle, it is determined whether the target battery has a self-discharge abnormality.

8. The method according to claim 6, characterized in that, Also includes: After the second charge-discharge cycle is completed, the decay rate of the open-circuit voltage of the target battery under preset conditions is obtained; Based on the decay rate of the open-circuit voltage, it is determined whether the target battery has a self-discharge abnormality.

9. A battery self-discharge detection device, characterized in that, include: The first processing module is used to control the target battery to perform a first charge-discharge cycle within a preset SOC range, wherein the thickness change rate of the electrode of the target battery in the first charge-discharge cycle is greater than or equal to a preset thickness change rate. The second processing module is used to determine whether the target battery has a self-discharge abnormality based on the first SOC change rate of the target battery during the first charge-discharge cycle.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the battery self-discharge detection method as described in any one of claims 1 to 8.

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