Battery lithium precipitation detection method and device, electronic equipment and storage medium

Abstract

The invention discloses a battery lithium precipitation detection method and device, electronic equipment and a storage medium. The battery lithium precipitation detection method comprises the following steps: acquiring current change data of a to-be-detected battery in a constant-voltage charging stage along with time change; performing first-order differential processing on the current change data to obtain a dI / dt-t curve of the battery to be detected; according to a target time period formed by time points corresponding to all inflection points in the dI / dt-t curve, target current change data in the target time period in the current change data are determined, and the reversible lithium precipitation amount of the to-be-measured battery is obtained according to the target current change data. The battery lithium precipitation detection method provided by the embodiment of the invention can quantitatively analyze the lithium precipitation degree of the battery.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method, device, electronic device and storage medium for detecting lithium deposition in a battery. Background Art

[0002] Lithium deposition in batteries is a common anomaly during the use of lithium-ion batteries. To detect lithium deposition in batteries, the battery is usually disassembled and observed to determine whether lithium deposition occurs. However, this method will damage the battery, has poor safety, and the detection results of lithium deposition are not accurate enough.

[0003] Therefore, in the related art, the battery is charged with constant current and constant voltage to determine whether the battery has lithium deposition according to the change in current density of the battery during constant current and constant voltage charging. However, this battery lithium deposition detection method can only perform a qualitative analysis of the battery's lithium deposition, but cannot detect the amount of reversible lithium deposition, and cannot determine the severity of the battery's lithium deposition, resulting in an inability to accurately determine the risk of battery use. Summary of the invention

[0004] In view of the above problems, the present application provides a battery lithium deposition detection method, device, electronic device and storage medium, which can quantitatively analyze the degree of lithium deposition of the battery.

[0005] In a first aspect, the present application provides a method for detecting lithium deposition in a battery, the method comprising: obtaining current change data of a battery to be tested that changes with time during a constant voltage charging stage; performing first-order differential processing on the current change data to obtain a dI / dt~t curve of the battery to be tested; and determining target current change data in the current change data that is in the target time period according to a target time period formed by time points corresponding to each inflection point in the dI / dt~t curve, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data.

[0006] In the technical solution of the embodiment of the present application, by obtaining the current change data of the battery to be tested that changes with time during the constant voltage charging stage, the current change data is subjected to first-order differential processing to obtain the dI / dt~t curve of the battery to be tested, and according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, the target current change data in the target time period is determined, so as to obtain the reversible lithium precipitation amount of the battery to be tested according to the target current change data. During the constant voltage charging process, the negative electrode of the battery is close to the full lithium embedding potential, and there is a potential difference with the lithium dendrites on the surface of the negative electrode, forming a concentration difference battery. If there is lithium precipitate in the battery, the precipitated lithium will be embedded back into the negative electrode. This lithium back embedding process will cause the current change data of the battery to be tested to fluctuate during the constant voltage charging stage, resulting in fluctuations in the corresponding dI / dt~t curve. During the lithium back-insertion process, the electrons transmitted during the constant voltage charging stage are all used for phase change reactions. Therefore, the target period of fluctuation in the dI / dt~t curve obtained by differentiating the current change data can be used to determine the target current change data corresponding to the lithium back-insertion process. At this time, the power determined by the target current change data can be used to represent the lithium capacity consumed during the back-insertion process, that is, the reversible lithium deposition amount of the battery to be tested. Therefore, the quantitative analysis of the lithium deposition degree of the battery to be tested can be achieved during the constant voltage charging stage of the battery to be tested, and the use risk of the battery can be accurately judged.

[0007] In some embodiments, the constant voltage charging stage is a period of time during which the battery to be tested is charged to a cut-off voltage, so that the acquired current variation data varying with time can better reflect the actual lithium deposition of the battery to be tested, and at the same time improve the safety of lithium deposition detection.

[0008] In some embodiments, according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, the target current change data in the target time period in the current change data is determined, including: when it is determined that the battery to be tested has lithium deposition according to the current change data, according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, the target current change data in the target time period in the current change data is determined. Thus, when it is determined that the battery to be tested has lithium deposition according to the dI / dt~t curve, the dI / dt~t curve is used to detect the reversible lithium deposition amount of the battery to be tested, reducing the number of invalid detections of the reversible lithium deposition amount of the battery to be tested, thereby improving the detection efficiency of the lithium deposition amount detection of the battery to be tested.

[0009] In some embodiments, according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, the target current change data in the current change data that is in the target time period is determined, including: when it is determined according to the dI / dt~t curve that the battery to be tested has lithium deposition, according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, the target current change data in the current change data that is in the target time period is determined. Since the dI / dt~t curve obtained by performing first-order differential processing on the current change data can be used to reflect the rate of change of the current change data, by detecting the dI / dt~t curve obtained by performing first-order differential processing on the current change data, it is possible to better judge whether the current change data has fluctuations, thereby being able to more accurately determine whether the battery to be tested has lithium deposition.

[0010] In some embodiments, according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, the target current change data in the current change data that is in the target time period is determined, including: performing high-order differential processing on the current change data to obtain the differential processing result corresponding to the current change data; when it is determined that the battery under test has lithium deposition according to the differential processing result, according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, the target current change data in the current change data that is in the target time period is determined. By performing high-order differential processing on the current change data, it is quickly determined whether the current change data has current fluctuations caused by lithium back-insertion during the constant voltage charging stage, so that it can be effectively determined whether the battery under test has lithium deposition.

[0011] In some embodiments, the reversible lithium deposition amount of the battery to be tested is obtained according to the target current change data, including: obtaining the reversible lithium deposition amount of the battery to be tested according to the current peak value in the target current change data, and the reaction time corresponding to the current peak value; wherein the reaction time corresponding to the current peak value is determined according to the difference between the constant-voltage charging time corresponding to the current peak value and the constant-voltage charging time corresponding to the first data point in the target current change data.

[0012] In some embodiments, obtaining the reversible lithium deposition amount of the battery to be tested according to the target current change data includes: obtaining a function model representing the corresponding relationship between the current value and the reaction time according to the current value and reaction time corresponding to each data point in the target current change data; According to the time interval determined by the reaction time corresponding to each of the data points, the function model is integrated to obtain the reversible lithium deposition amount of the battery to be tested; wherein, the reaction time corresponding to any of the data points is determined according to the constant voltage charging time corresponding to the data point and the difference between the constant voltage charging time corresponding to the first data point in the target current change data. Thus, the reversible lithium deposition amount in the entire lithium back-insertion process can be obtained more accurately, thereby further improving the accuracy of lithium deposition amount detection.

[0013] In some embodiments, the method further includes: obtaining the irreversible lithium deposition amount of the battery to be tested based on the total amount of lithium involved in charging of the battery to be tested during the constant voltage charging stage, the lithium capacity embedded in the anode of the battery to be tested during the constant voltage charging stage, and the reversible lithium deposition amount, thereby enabling a more comprehensive quantitative analysis of the lithium deposition of the battery to be tested.

[0014] In a second aspect, the present application provides a battery lithium deposition detection device, comprising: a current data acquisition module, used to obtain the current change data of the battery to be tested that changes with time during the constant voltage charging stage; a current data processing module, used to perform first-order differential processing on the current change data to obtain the dI / dt~t curve of the battery to be tested; a battery lithium deposition detection module, used to determine the target current change data in the current change data that is in the target time period according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data.

[0015] In the technical solution of the embodiment of the present application, the solution obtains the current change data of the battery to be tested that changes with time during the constant voltage charging stage, performs first-order differential processing on the current change data, obtains the dI / dt~t curve of the battery to be tested, and determines the target current change data in the target period in the current change data according to the target period formed by the time points corresponding to the inflection points in the dI / dt~t curve, so as to obtain the reversible lithium precipitation amount of the battery to be tested according to the target current change data. Thus, the quantitative analysis of the lithium precipitation degree of the battery can be realized during the constant voltage charging stage of the battery to be tested, and the use risk of the battery can be accurately judged.

[0016] In some embodiments, the constant voltage charging stage is a period of time in which the battery under test is charged to a cut-off voltage and the battery under test is charged at a constant voltage.

[0017] In some embodiments, the battery lithium deposition detection module is specifically used to: when it is determined that the battery to be tested has lithium deposition according to the current change data, determine the target current change data in the target time period according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve.

[0018] In some embodiments, the battery lithium deposition detection module is specifically used to: when it is determined that the battery to be tested has lithium deposition according to the dI / dt~t curve, determine the target current change data in the current change data that is in the target time period according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve.

[0019] In some embodiments, the battery lithium deposition detection module is specifically used to: perform high-order differential processing on the current change data to obtain a differential processing result corresponding to the current change data; when it is determined that lithium deposition exists in the battery to be tested according to the differential processing result, determine the target current change data in the current change data that is in the target time period according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve.

[0020] In some embodiments, the battery lithium deposition detection module is specifically used to: obtain the reversible lithium deposition amount of the battery to be tested according to the current peak value in the target current change data, and the reaction time corresponding to the current peak value; wherein the reaction time corresponding to the current peak value is determined according to the difference between the constant-voltage charging time corresponding to the current peak value and the constant-voltage charging time corresponding to the first data point in the target current change data.

[0021] In some embodiments, the battery lithium deposition detection module is specifically used to: obtain a function model representing the corresponding relationship between the current value and the reaction time according to the current value and reaction time corresponding to each data point in the target current change data; integrate the function model according to the time interval determined by the reaction time corresponding to each data point to obtain the reversible lithium deposition amount of the battery to be tested; wherein the reaction time corresponding to any of the data points is determined according to the difference between the constant-voltage charging time corresponding to the data point and the constant-voltage charging time corresponding to the first data point in the target current change data.

[0022] In some embodiments, the battery lithium deposition detection module is also used to obtain the irreversible lithium deposition amount of the battery to be tested based on the total amount of lithium involved in charging of the battery to be tested during the constant voltage charging stage, the lithium capacity embedded in the anode of the battery to be tested during the constant voltage charging stage, and the reversible lithium deposition amount.

[0023] In a third aspect, the present application provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor executes the method in the implementation of the first aspect when executing the computer program.

[0024] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, performs the method in the implementation of the first aspect.

[0025] In a fifth aspect, the present application provides a computer program product, which, when running on a computer, enables the computer to execute the method in the first aspect, any optional implementation manner in the first aspect, or the third aspect, any optional implementation manner in the third aspect.

[0026] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings: Figure 1 This is a first flow chart of a method for detecting battery lithium deposition in some embodiments of the present application; Figure 2 A schematic diagram of current variation data of some embodiments of the present application; Figure 3 A schematic diagram of a dI / dt~t curve of a battery in some embodiments of the present application; Figure 4 A second flow chart of a method for detecting battery lithium deposition in some embodiments of the present application; Figure 5 A schematic diagram of the structure of a battery lithium deposition detection device according to some embodiments of the present application; Figure 6 This is a schematic diagram of the structure of an electronic device according to some embodiments of the present application.

[0028] The reference numerals in the specific implementation manner are as follows: 300 - current data acquisition module; 301 - current data processing module; 302 - battery lithium deposition detection module; 400 - electronic device; 401 - processor; 402 - memory; 403 - communication bus. DETAILED DESCRIPTION

[0029] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0031] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0032] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0034] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0035] The lithium deposition problem of batteries is a common anomaly during the use of lithium-ion batteries. If lithium deposition occurs in the battery, it will cause the battery capacity to decay, accelerate battery aging, and affect the use of the battery. Therefore, it is usually necessary to test the battery for lithium deposition to detect batteries with the risk of lithium deposition. At present, the detection of battery lithium deposition is usually carried out by disassembling the battery and observing it to determine whether lithium deposition occurs. However, this method has problems such as damage to the battery, poor safety, and the inability to quantify the degree of lithium deposition through visual inspection.

[0036] To this end, in the related art, the battery is charged with constant current and constant voltage, and the change in the current density of the battery during the constant current and constant voltage charging is calculated, so as to determine whether the battery has lithium deposition according to the change in the current density of the battery during the constant current and constant voltage charging. However, this battery lithium deposition detection method can only perform a qualitative analysis of the battery's lithium deposition, but cannot detect the amount of reversible lithium deposition, and cannot determine the severity of the battery's lithium deposition, resulting in an inability to accurately judge the risk of battery use.

[0037] In view of the above technical problems, an embodiment of the present application provides a method for detecting lithium deposition in a battery. The method obtains the current change data of the battery to be tested that changes with time during the constant voltage charging stage, performs first-order differential processing on the current change data, obtains the dI / dt~t curve of the battery to be tested, and determines the target current change data in the current change data and in the target time period according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data. Since the negative electrode of the battery is close to the full lithium embedding potential in the constant voltage charging process, there is a potential difference with the lithium dendrites on the surface of the negative electrode, forming a concentration difference battery. If there is lithium deposition in the battery, the deposited lithium will be embedded back into the negative electrode. This lithium embedding process will cause the current change data of the battery to be tested to fluctuate during the constant voltage charging stage, resulting in fluctuations in the corresponding dI / dt~t curve. During the lithium back-insertion process, the electrons transmitted during the constant voltage charging stage are all used for phase change reactions. Therefore, the target period of fluctuation in the dI / dt~t curve obtained by differentiating the current change data can be used to determine the target current change data corresponding to the lithium back-insertion process. At this time, the power determined by the target current change data can be used to represent the lithium capacity consumed during the back-insertion process, that is, the reversible lithium deposition amount of the battery to be tested. Therefore, the quantitative analysis of the lithium deposition degree of the battery to be tested can be achieved during the constant voltage charging stage of the battery to be tested, and the use risk of the battery can be accurately judged.

[0038] The battery lithium deposition detection method, device, electronic device and storage medium disclosed in the embodiments of the present application can be applied to terminal devices to detect the amount of lithium deposition of the battery to be tested. The terminal device can be any terminal device such as a mobile terminal, a desktop terminal, a vehicle-mounted terminal, a BMS (Battery Management System) or a server. The server can be an independent server or a server cluster composed of multiple servers. It can also be a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, and big data and artificial intelligence sampling point devices.

[0039] According to some embodiments of the present application, a method for detecting lithium deposition in a battery according to an embodiment of the present application can be applied to the aforementioned terminal device. Figure 1 As shown, the battery lithium deposition detection method includes: S101, obtaining current change data of the battery under test that changes with time during a constant voltage charging stage; S102, performing first-order differential processing on the current change data to obtain a dI / dt-t curve of the battery to be tested; S103, according to a target time period formed by time points corresponding to inflection points in the dI / dt~t curve, determining target current change data in the current change data that is in the target time period, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data.

[0040] In some embodiments, the battery to be tested may include a lithium-ion battery, such as a lithium iron phosphate, lithium iron manganese phosphate, or lithium manganese oxide battery.

[0041] The terminal device can be connected to a power source for charging the battery under test to control the power source to charge the battery under test. The terminal device controls the power source to charge the battery under test by controlling the power source to directly adopt a constant voltage charging mode to charge the battery under test, or by controlling the power source to adopt a constant current constant voltage charging mode to charge the battery under test until the battery under test is fully charged. The battery under test can include a single battery cell or multiple battery cells, and each battery cell can be connected in series, in parallel, or in a mixed manner to form the battery under test.

[0042] During the charging process of the battery under test, the charging current of the battery under test in the constant voltage charging stage can be collected to obtain the current change data of the battery under test over time in the constant voltage charging stage, such as the time-current curve. The constant voltage charging stage refers to the time period when the battery under test is under constant voltage charging.

[0043] After obtaining the current variation data of the battery under test that varies with time during the constant voltage charging stage, the current variation data can be subjected to first-order differential processing, that is, the first-order derivative calculation is performed on the current variation data to obtain the dI / dt~t curve of the battery under test that varies with time.

[0044] During the charging process of lithium-ion batteries, lithium ions are transferred from the cathode to the anode. If the transfer path is blocked, the lithium ions will precipitate on the surface of the negative electrode, causing lithium deposition, resulting in the loss of active lithium and a decrease in capacity. During the charging process, lithium ions form LiCX compounds with the negative electrode graphite of the battery. At the end of the constant voltage charging stage, the negative electrode of the battery is close to fully embedded with lithium potential, and there is a potential difference with the lithium dendrites on the surface of the negative electrode, forming a concentration difference battery. If the battery has lithium deposition, the non-dead lithium part of the precipitated lithium will be embedded back into the negative electrode. This lithium embedding process will cause the current change data of the battery under test to fluctuate during the constant voltage charging stage. Figure 2 As shown, curve A represents the current change data of the battery without lithium deposition at the end of the constant voltage charging stage, and curve A' represents the current change data of the battery with lithium deposition at the end of the constant voltage charging stage. If the current change data fluctuates, the corresponding dI / dt~t curve will have a fluctuation section that rises and then falls over time, and this fluctuation section corresponds to the lithium back-insertion process. Figure 3 As shown, curve B represents the dI / dt~t curve corresponding to normal current change data, and curve B' represents the dI / dt~t curve corresponding to the current change data with fluctuations. During the lithium back-intercalation process, the battery is equivalent to a circuit in parallel. At this time, the electrons transmitted in the circuit are all used for phase change reactions, that is, during the lithium back-intercalation process, the transmitted electrons are all used for phase change reactions. At this time, the product of the reaction time t and the corresponding current I can represent the capacity consumed by the reversible lithium reaction, that is, the reversible lithium precipitation amount of the battery Q=I·t. Among them, the reaction time t refers to the duration of the phase change reaction during the lithium back-intercalation process.

[0045] Therefore, after obtaining the dI / dt~t curve of the battery to be tested, the dI / dt~t curve can be detected from small to large along the time axis to obtain each inflection point in the dI / dt~t curve. The curve segment of the dI / dt~t curve between the first inflection point and the last inflection point of each inflection point is the fluctuation curve segment corresponding to the lithium reinsertion process. Among them, for the detection of any inflection point in the dI / dt~t curve, it can be to derive each data point in the dI / dt~t curve except the endpoints, and obtain the data point in the dI / dt~t curve where the second-order derivative is 0, which is the inflection point in the dI / dt~t curve. Alternatively, other conventional inflection point detection methods can be used to determine the inflection points in the dI / dt~t curve. After obtaining the fluctuation curve segment, the target time period can be determined based on the constant voltage charging time corresponding to the two endpoints in the fluctuation curve segment. Such as Figure 3 As shown, assuming that the constant voltage charging time of the first endpoint in the fluctuation curve segment, that is, the first inflection point among the inflection points, is t1, and the constant voltage charging time of the last endpoint in the fluctuation curve segment, that is, the last inflection point among the inflection points, is t2, the target time period can be determined to be [t1, t2].

[0046] After obtaining the target time period, the current change data corresponding to the target time period can be intercepted from the current change data according to the target time period, that is, the current change data of the target time period [t1, t2] is intercepted as the target current change data, and the target current change data can be used to represent the current change during the lithium reinsertion process.

[0047] Since the target current change data is used to represent the current change during the lithium reinsertion process, the electrons transmitted by the target current change data are all used for phase change reactions. At this time, the transmitted power calculated using the target current change data can be determined as the reversible lithium deposition amount of the battery to be tested.

[0048] Exemplarily, since the target current change data represents the current change during the lithium back-intercalation process, the moment corresponding to the first data point in the target current data represents the starting moment of the lithium back-intercalation process, and the moment corresponding to the last data point in the target current data represents the ending moment of the lithium back-intercalation process. Based on this, after obtaining the target current change data, the constant voltage charge length T1 of the first data point of the target current change data and the constant voltage charge length T2 of the last data point in the target current data can be obtained to obtain the reaction time (T2-T1) of the entire lithium back-intercalation process. After obtaining the reaction time (T2-T1) of the entire lithium back-intercalation process, the reversible lithium precipitation amount of the battery to be tested can be obtained as Q1=(T2-T1)×I0 according to the reaction time (T2-T1) of the entire lithium back-intercalation process and the current value I0 corresponding to the last data point in the target current data.

[0049] The battery lithium deposition detection method designed above obtains the current change data of the battery to be tested that changes with time during the constant voltage charging stage, performs first-order differential processing on the current change data, obtains the dI / dt~t curve of the battery to be tested, and determines the target current change data in the target period in the current change data according to the target period formed by the time points corresponding to the inflection points in the dI / dt~t curve, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data. During the constant voltage charging process, the negative electrode of the battery is close to the full lithium embedding potential, and there is a potential difference with the lithium dendrites on the surface of the negative electrode, forming a concentration difference battery. If the battery has lithium deposition, the deposited lithium will be embedded back into the negative electrode. This lithium embedding process will cause the current change data of the battery to be tested to fluctuate during the constant voltage charging stage, resulting in fluctuations in the corresponding dI / dt~t curve. During the lithium back-insertion process, the electrons transmitted during the constant voltage charging stage are all used for phase change reactions. Therefore, the target period of fluctuation in the dI / dt~t curve obtained by differentiating the current change data can be used to determine the target current change data corresponding to the lithium back-insertion process. At this time, the power determined by the target current change data can be used to represent the lithium capacity consumed during the back-insertion process, that is, the reversible lithium deposition amount of the battery to be tested. Therefore, the quantitative analysis of the lithium deposition degree of the battery to be tested can be achieved during the constant voltage charging stage of the battery to be tested, and the use risk of the battery can be accurately judged.

[0050] Considering that when the battery to be tested is charged to perform lithium deposition detection on the battery to be tested, if the battery to be tested is directly charged at a constant voltage, the charging rate at the initial charging stage may be too large, which will aggravate the material loss of the battery to be tested and the lithium deposition phenomenon of the battery to be tested. To this end, in some embodiments, the constant voltage charging stage is a period of time during which the battery to be tested is charged to a cut-off voltage and the battery to be tested is charged at a constant voltage.

[0051] In some embodiments, when it is necessary to perform lithium plating detection on the battery to be tested, the power supply can be first controlled to adopt a constant current charging mode to charge the battery to be tested until the battery to be tested is charged to a cut-off voltage, and then the battery to be tested is controlled to enter a constant current charging stage. For example, the power supply is controlled to adopt a constant voltage charging mode to charge the battery to be tested at the cut-off voltage, and the current change data of the battery to be tested that changes with time during the constant current charging stage is obtained.

[0052] Since the battery under test has reached the cut-off voltage when entering the constant voltage charging stage, the battery under test will be charged at a small rate of charging current, reducing the impact of the constant voltage charging stage on the material loss and lithium deposition of the battery under test, so that the current change data obtained over time can better reflect the actual lithium deposition of the battery under test, while improving the safety of lithium deposition detection.

[0053] In order to avoid invalid detection of the lithium deposition amount of the battery to be tested, in some embodiments, according to the target time period of abnormal fluctuation in the dI / dt~t curve, the target current change data in the current change data that is in the target time period is determined, including: when it is determined that lithium deposition exists in the battery to be tested according to the current change data, according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, the target current change data in the current change data that is in the target time period is determined.

[0054] As a possible implementation method, if the battery to be tested has lithium deposition, its transmission path in the constant voltage charging stage is blocked, resulting in a slower current reduction rate than the current reduction rate of a normal battery with lithium deposition in the constant voltage charging stage, and its current change data will fluctuate, which is different from the current change data of a normal battery. Among them, a normal battery refers to a battery with the same product information as the battery to be tested. For example, the capacity, size, model, and material of a normal battery are the same as those of the battery to be tested. Therefore, the current change data of a normal battery without lithium deposition during the constant voltage charging stage over time can be obtained first, and the current change data of a normal battery over time can be compared with the current change data of a battery to be tested over time to determine whether the battery to be tested has lithium deposition. If the current change data of the battery to be tested matches the current change data of a normal battery, such as a similarity of 90%, it can be determined that the battery to be tested is a normal battery and there is no lithium deposition; otherwise, it can be determined that the battery to be tested is an abnormal battery and there is lithium deposition.

[0055] As another possible implementation, if the battery to be tested does not have lithium deposition, the current will gradually decrease until it reaches zero during the constant voltage charging stage. Therefore, if the battery to be tested does not have lithium deposition, then during the constant voltage charging stage, its current change data that changes with time is monotonically decreasing current change data, and the slope of any data point in the current change data is less than or equal to zero. If the battery to be tested has lithium deposition, then in the later stage of the constant voltage charging stage, the inside of the negative electrode graphite is close to the full lithium embedding potential LiC6, and there is a potential difference with the lithium dendrites on the surface of the negative electrode, forming a concentration difference battery, so that the non-dead lithium part of the precipitated lithium is embedded back into the graphite. At this time, the current change data that changes with time may show an increase in charging current, which is manifested in the data points with an increased slope in the current change data. Based on this, after obtaining the current change data of the battery to be tested that changes with time, it can be detected whether there are data points with a slope greater than zero in the current change data. If it exists, it can be determined that the battery to be tested is an abnormal battery and lithium deposition occurs; otherwise, it can be determined that the battery to be tested is a normal battery and there is no lithium deposition.

[0056] After determining whether the battery to be tested has lithium deposition, if there is no lithium deposition, the detection of the reversible lithium deposition amount of the battery to be tested can be stopped. If there is lithium deposition, the dI / dt~t curve is detected again to determine the inflection points in the dI / dt~t curve, and the target time period between the first inflection point and the last inflection point is determined according to the time points corresponding to the inflection points. According to the target time period, the target current change data in the current change data in the target time period is determined, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data. Therefore, when it is determined that the battery to be tested has lithium deposition according to the current change data, the reversible lithium deposition amount of the battery to be tested is detected by the dI / dt~t curve, so as to reduce the number of invalid detections of the reversible lithium deposition amount of the battery to be tested, thereby improving the detection efficiency of the reversible lithium deposition amount of the battery to be tested.

[0057] Considering that if lithium deposition occurs in the battery to be tested, its current change data will fluctuate, and accordingly, the dI / dt~t curve obtained after the first-order differential will also fluctuate. Therefore, in some embodiments, according to the target period of abnormal fluctuation in the dI / dt~t curve, determining the target current change data in the target period in the current change data includes: When it is determined according to the dI / dt~t curve that lithium deposition occurs in the battery to be tested, target current change data in the target time period is determined in the current change data according to a target time period formed by time points corresponding to inflection points in the dI / dt~t curve.

[0058] As a possible implementation method, if the battery to be tested has lithium deposition, a curve segment that rises and then falls back will appear in the dI / dt~t curve obtained by first-order differentiation of the current change data, which is different from the dI / dt~t curve of a normal battery without lithium deposition. Therefore, the current change data of a normal battery without lithium deposition that changes with time during the constant voltage charging stage can be obtained first, and the current change data can be processed by first-order differentiation to obtain the dI / dt~t curve of the normal battery. Then the dI / dt~t curve of the battery to be tested is compared with the dI / dt~t curve of the normal battery to determine whether the battery to be tested has lithium deposition. If the dI / dt~t curve of the battery to be tested is consistent with the dI / dt~t curve of the normal battery, it can be determined that the battery to be tested is a normal battery and there is no lithium deposition; otherwise, it can be determined that the battery to be tested is abnormal and there is lithium deposition.

[0059] As another possible implementation, if the battery to be tested does not have lithium deposition, the dI / dt~t curve obtained by first-order differentiation of its current change data is usually a monotonically increasing curve, and the dI / dt value corresponding to each time point t is different. If the battery to be tested has lithium deposition, its dI / dt~t curve will fluctuate, that is, there will be a curve segment in the dI / dt~t curve that rises and then falls back, resulting in a dI / dt value rebound in the dI / dt~t curve of the battery to be tested, that is, there are two different time points t corresponding to the same dI / dt value. Therefore, it is possible to detect whether there are two identical dI / dt values ​​in the dI / dt~t curve of the battery to be tested, that is, to determine whether f(t)=dI / dt=f(t+n). If not, it means that the dI / dt~t curve is a monotonically increasing curve, and at this time it can be determined that the battery to be tested is a normal battery and there is no lithium deposition phenomenon; otherwise, it can be determined that the battery to be tested is abnormal and there is lithium deposition phenomenon.

[0060] If lithium deposition occurs, the dI / dt~t curve is detected again to determine the inflection points in the dI / dt~t curve, and after determining the target period between the first inflection point and the last inflection point according to the time points corresponding to the inflection points, the target current change data in the current change data in the target period is determined according to the target period, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data. Since the dI / dt~t curve obtained by performing the first-order differential processing on the current change data can be used to reflect the rate of change of the current change data, by performing the first-order differential processing on the current change data to obtain the dI / dt~t curve, it is possible to better judge whether the battery to be tested has lithium deposition, so that when it is determined that the battery to be tested has lithium deposition, the dI / dt~t curve is used to detect the reversible lithium deposition amount of the battery to be tested, thereby reducing the number of invalid detections of the reversible lithium deposition amount of the battery to be tested, and thus improving the detection efficiency of the reversible lithium deposition amount of the battery to be tested.

[0061] In order to more effectively determine whether the battery to be tested has lithium deposition, in some embodiments, a detection result of lithium deposition of the battery to be tested is obtained based on the current change data, including: performing high-order differential processing on the current change data to obtain a differential processing result corresponding to the current change data; when it is determined that the battery to be tested has lithium deposition based on the differential processing result, based on a target time period formed by time points corresponding to each inflection point in the dI / dt~t curve, determine target current change data in the current change data that is in the target time period.

[0062] As a possible implementation method, the current change data can be subjected to second-order differential processing to obtain the differential processing result corresponding to the current change data. Since if there is no lithium deposition in the battery to be tested, the current change data that changes with time does not fluctuate, and its second-order differentials are all greater than or equal to zero or are all less than or equal to zero. On the contrary, if there is lithium deposition in the battery to be tested, the current increases during the process of lithium reinsertion, causing the current change data to fluctuate. At this time, there may be data points in the current change data whose second-order differential is greater than zero and data points whose second-order differential is less than zero. Therefore, after obtaining the current change data of the battery to be tested, the current change data can be subjected to second-order differential processing to obtain the differential processing result corresponding to the current change data. If the differential processing result is that each data point of the current change data is greater than or equal to zero or is less than or equal to zero, it means that there is no fluctuation in the current change data, and it can be determined that there is no lithium deposition in the battery to be tested; on the contrary, it can be determined that there is lithium deposition in the battery to be tested.

[0063] As another possible implementation, the current change data can be subjected to a third-order differential process to obtain a differential processing result corresponding to the current change data. Specifically, the current change data is first subjected to a first-order differential process to obtain a dI / dt~t curve, and then the dI / dt~t curve is subjected to a second-order differential process to obtain a differential processing result corresponding to the current change data. Since if there is no lithium deposition in the battery to be tested, the current change data that changes with time does not fluctuate, and the dI / dt~t curve obtained after the first-order differential process does not fluctuate, which is manifested as the dI / dt~t curve having no inflection point, and the second-order differential of each data point in the dI / dt~t curve being greater than or equal to zero or less than or equal to zero. On the contrary, if there is lithium deposition in the battery to be tested, the current increases during the lithium back-insertion process, causing the dI / dt~t curve to fluctuate. At this time, the dI / dt~t curve has multiple data points that are inflection points, and accordingly, there may be data points in the dI / dt~t curve with a second-order differential greater than zero and data points with a second-order differential less than zero. Therefore, after obtaining the current change data of the battery to be tested, the current change data can be subjected to third-order differential processing to obtain the differential processing result corresponding to the current change data. If the differential processing result is that each data point of the current change data is greater than or equal to zero or less than or equal to zero, it means that there is no fluctuation in the current change data, and it can be determined that the battery to be tested does not have lithium deposition; otherwise, it can be determined that the battery to be tested has lithium deposition.

[0064] If lithium deposition occurs, the dI / dt~t curve is tested again to determine the inflection points in the dI / dt~t curve, and the target time period between the first inflection point and the last inflection point is determined according to the time points corresponding to the inflection points. According to the target time period, the target current change data in the current change data in the target time period is determined, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data. In this way, by performing high-order differential processing on the current change data, it is possible to quickly determine whether there is current fluctuation caused by lithium back-insertion in the current change data during the constant voltage charging stage, so as to effectively determine whether there is lithium deposition in the battery to be tested, so as to use the dI / dt~t curve to detect the reversible lithium deposition amount of the battery to be tested when it is determined that there is lithium deposition in the battery to be tested, thereby improving the detection efficiency of the reversible lithium deposition amount detection of the battery to be tested.

[0065] To further improve the accuracy of reversible lithium deposition detection, in some embodiments, the reversible lithium deposition amount of the battery to be tested is obtained according to the target current change data, including: obtaining the reversible lithium deposition amount of the battery to be tested according to the current peak value in the target current change data, and the reaction time corresponding to the current peak value; wherein the reaction time corresponding to the current peak value is determined based on the difference between the constant-voltage charging time corresponding to the current peak value and the constant-voltage charging time corresponding to the first data point in the target current change data.

[0066] Considering that during the lithium back-intercalation process, the battery to be tested may continue to precipitate lithium, and as the amount of lithium precipitated increases, the potential difference between the lithium dendrites inside the negative electrode graphite and the surface of the negative electrode will gradually increase, and the charging current will increase synchronously until the amount of lithium precipitated reaches a peak value, the potential difference falls back, and the charging current gradually decreases. Therefore, after obtaining the target current change data, the current peak value in the target current change data can be obtained, and the current peak value can indicate that the amount of lithium precipitated by the battery to be tested has reached a peak value. Among them, for the acquisition of the current peak value, it can be determined according to the peak of the fluctuation curve segment in the dI / dt~t curve. Exemplarily, during the lithium back-intercalation process, the potential difference will gradually increase and then fall back, and correspondingly, the fluctuation curve segment in the dI / dt~t curve will appear as a curve image that first increases and then decreases, and the moment corresponding to the peak of the fluctuation curve segment can indicate that the potential difference of the lithium dendrite reaches a peak value, that is, the moment corresponding to the peak value of the lithium precipitated amount. Therefore, the current data corresponding to the peak can be determined from the target current change data as the current peak value in the target current change data.

[0067] After obtaining the current peak value in the target current change data, the reaction time T3-T1 corresponding to the phase change reaction when the reversible lithium deposition amount is at the peak value can be obtained based on the constant voltage charging time T3 corresponding to the current peak value and the constant voltage charging time T1 corresponding to the first data point in the target current change data. The reaction time T3-T1 is the reaction time corresponding to the current peak value. According to the reaction time T3-T1 and the current peak value Imax in the target current change data, the reversible lithium deposition amount Q1 of the battery to be tested can be obtained as Q1=Imax×(T3-T1).

[0068] In order to further improve the accuracy of the reversible lithium deposition amount detection, in some embodiments, the reversible lithium deposition amount of the battery to be tested is obtained according to the target current change data, including: According to the current value and reaction time corresponding to each data point in the target current change data, a function model representing the corresponding relationship between the current value and the reaction time is obtained; According to the time interval determined by the reaction time corresponding to each of the data points, the function model is integrated to obtain the reversible lithium deposition amount of the battery to be tested; The reaction time corresponding to any of the data points is determined according to the difference between the constant-voltage charging time corresponding to the data point and the constant-voltage charging time corresponding to the first data point in the target current change data.

[0069] In some embodiments, after obtaining the target current change data, the reaction time corresponding to any data point can be obtained according to the constant voltage charging time corresponding to any data point in the target current change data and the difference between the constant voltage charging time corresponding to the first data point in the target current change data. For example, if the constant voltage charging time of any data point a in the target current change data is Tx, and the constant voltage charging time of the first data point in the target current change data is T1, then the reaction time corresponding to the data point a can be obtained as Tx-T1. After obtaining the reaction time corresponding to each data point in the target current data, the reversible lithium precipitation amount of the battery to be tested can be obtained by performing integration processing according to the reaction time corresponding to each data point and the current value corresponding to each data point.

[0070] For example, the reaction time and current value corresponding to each data point in the target current change data can be used to generate a function model f(t) with the reaction time t as the independent variable and the current value as the dependent variable. Then, the function model f(t) can be integrated to obtain the reversible lithium precipitation amount Q1 of the battery to be tested: . Among them, [a,b] represents the duration interval composed of the reaction duration corresponding to each data point, a represents the reaction duration corresponding to the first data point of the target current change data, b represents the reaction duration corresponding to the last data point of the target current change data, that is, a represents the minimum reaction duration corresponding to each data point, and b represents the maximum reaction duration corresponding to each data point. In this way, the amount of reversible lithium deposition in the entire lithium back-insertion process can be obtained more accurately, thereby further improving the accuracy of lithium deposition detection.

[0071] Considering that dead lithium that cannot be re-intercalated may exist during the lithium re-intercalation process, in order to more comprehensively perform quantitative analysis of lithium deposition on the battery, in some embodiments, the method further includes: The irreversible lithium deposition amount of the battery under test is obtained according to the total lithium amount participating in the charging reaction of the battery under test during the constant voltage charging stage, the lithium capacity embedded in the anode of the battery under test during the constant voltage charging stage, and the reversible lithium deposition amount.

[0072] Among them, the lithium capacity embedded in the anode of the battery to be tested during the constant voltage charging stage refers to the lithium capacity embedded in the anode of the battery to be tested during the constant voltage charging stage, except for the time period corresponding to the target current change data.

[0073] The total amount of lithium involved in the charging of the battery under test during the constant voltage charging stage can be obtained by integrating the current change data. The lithium capacity embedded in the anode of the battery under test during the constant voltage charging stage can be obtained by experimental measurement.

[0074] After obtaining the total lithium amount Q involved in the constant voltage charging stage of the battery under test, the lithium capacity Q2 embedded in the anode of the battery under test during the constant voltage charging stage, and the reversible lithium deposition amount Q1 of the battery under test, the dead lithium amount of the battery under test, that is, the irreversible lithium deposition amount Q3, can be obtained as Q3=Q-Q1-Q2. This enables a more comprehensive quantitative analysis of the lithium deposition of the battery under test.

[0075] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution in the present application will be described clearly and completely below. In some embodiments, Figure 4 As shown, the battery lithium deposition detection method includes: S201, when the battery to be tested is charged at a constant current to a cut-off voltage, controlling the battery to be tested to enter a constant voltage charging phase.

[0076] S202, obtaining current change data of the battery to be tested that changes with time during a constant voltage charging stage.

[0077] S203, performing differential processing on the current change data to obtain a differential processing result corresponding to the current change data, so as to obtain a lithium deposition phenomenon detection result of the battery to be tested according to the differential processing result. The differential processing includes first-order differential processing or high-order differential processing, and the high-order differential processing includes second-order differential processing or third-order differential processing.

[0078] S204, determining whether the lithium deposition phenomenon detection result of the battery to be tested indicates that lithium deposition phenomenon exists, if so, executing S205, otherwise, ending the detection.

[0079] S205, obtaining a target time period according to the time points corresponding to the inflection points in the dI / dt-t curve obtained by performing first-order differential processing on the current change data.

[0080] S206 , determining target current change data in the target period in the current change data according to the target period.

[0081] S207, according to the current peak value in the target current change data, and the reaction time corresponding to the current peak value, obtain the reversible lithium deposition amount of the battery to be tested; or, according to the current value and reaction time corresponding to each data point in the target current change data, obtain a function model representing the corresponding relationship between the current value and the reaction time, and integrate the function model according to the time interval determined according to the reaction time corresponding to each data point to obtain the reversible lithium deposition amount of the battery to be tested.

[0082] The reaction time corresponding to any data point in the target current change data is determined according to the constant voltage charging time corresponding to the data point and the constant voltage charging time corresponding to the first data point in the target current change data.

[0083] S208, obtaining the irreversible lithium deposition amount of the battery under test according to the total lithium amount involved in charging of the battery under test during the constant voltage charging stage, the lithium capacity embedded in the anode of the battery under test during the constant voltage charging stage, and the reversible lithium deposition amount.

[0084] Figure 5 The present application provides a schematic diagram of the structure of a battery lithium deposition detection device. It should be understood that the device is Figure 1 and 4The method embodiment executed in corresponds to the method embodiment, and the steps involved in the aforementioned method can be executed. The specific functions of the device can be referred to the description above. To avoid repetition, detailed description is appropriately omitted here. The device includes at least one software function module that can be stored in a memory or solidified in the operating system (OS) of the device in the form of software or firmware. Specifically, the device includes: a current data acquisition module 300, which is used to obtain the current change data of the battery to be tested that changes with time during the constant voltage charging stage; a current data processing module 301, which is used to perform first-order differential processing on the current change data to obtain the dI / dt~t curve of the battery to be tested; a battery lithium deposition detection module 302, which is used to determine the target current change data in the target period in the current change data according to the target period formed by the time points corresponding to each inflection point in the dI / dt~t curve, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data.

[0085] In the technical solution of the embodiment of the present application, by obtaining the current change data of the battery to be tested that changes with time during the constant voltage charging stage, the current change data is subjected to first-order differential processing to obtain the dI / dt~t curve of the battery to be tested, and according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, the target current change data in the target time period is determined, so as to obtain the reversible lithium precipitation amount of the battery to be tested according to the target current change data. During the constant voltage charging process, the negative electrode of the battery is close to the full lithium embedding potential, and there is a potential difference with the lithium dendrites on the surface of the negative electrode, forming a concentration difference battery. If there is lithium precipitate in the battery, the precipitated lithium will be embedded back into the negative electrode. This lithium back embedding process will cause the current change data of the battery to be tested to fluctuate during the constant voltage charging stage, resulting in fluctuations in the corresponding dI / dt~t curve. During the lithium back-insertion process, the electrons transmitted during the constant voltage charging stage are all used for phase change reactions. Therefore, the target period of fluctuation in the dI / dt~t curve obtained by differentiating the current change data can be used to determine the target current change data corresponding to the lithium back-insertion process. At this time, the power determined by the target current change data can be used to represent the lithium capacity consumed during the back-insertion process, that is, the reversible lithium deposition amount of the battery to be tested. Therefore, the quantitative analysis of the lithium deposition degree of the battery to be tested can be achieved during the constant voltage charging stage of the battery to be tested, and the use risk of the battery can be accurately judged.

[0086] According to some embodiments of the present application, the constant voltage charging stage is a period of time in which the battery to be tested is charged at a constant voltage when the battery to be tested is charged to a cut-off voltage.

[0087] According to some embodiments of the present application, the battery lithium deposition detection module 302 is specifically used to: when it is determined that the battery to be tested has lithium deposition according to the current change data, determine the target current change data in the target time period according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve.

[0088] According to some embodiments of the present application, the battery lithium deposition detection module 302 is specifically used to: when it is determined that the battery to be tested has lithium deposition according to the dI / dt~t curve, determine the target current change data in the current change data that is in the target time period according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve.

[0089] According to some embodiments of the present application, the battery lithium deposition detection module 302 is specifically used to: perform high-order differential processing on the current change data to obtain a differential processing result corresponding to the current change data; when it is determined that lithium deposition exists in the battery to be tested according to the differential processing result, determine the target current change data in the current change data that is in the target time period according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve.

[0090] According to some embodiments of the present application, the battery lithium deposition detection module 302 is specifically used to: obtain the reversible lithium deposition amount of the battery to be tested according to the current peak value in the target current change data, and the reaction time corresponding to the current peak value; wherein the reaction time corresponding to the current peak value is determined according to the difference between the constant-voltage charging time corresponding to the current peak value and the constant-voltage charging time corresponding to the first data point in the target current change data.

[0091] According to some embodiments of the present application, the battery lithium deposition detection module 302 is specifically used to: obtain a function model representing the corresponding relationship between the current value and the reaction time according to the current value and reaction time corresponding to each data point in the target current change data; integrate the function model according to the time interval determined by the reaction time corresponding to each data point to obtain the reversible lithium deposition amount of the battery to be tested; wherein the reaction time corresponding to any of the data points is determined according to the constant-voltage charging time corresponding to the data point and the difference between the constant-voltage charging time corresponding to the first data point in the target current change data.

[0092] According to some embodiments of the present application, the battery lithium deposition detection module 302 is also used to obtain the irreversible lithium deposition amount of the battery to be tested based on the total amount of lithium involved in the charging of the battery to be tested during the constant voltage charging stage, the lithium capacity embedded in the anode of the battery to be tested during the constant voltage charging stage, and the reversible lithium deposition amount.

[0093] According to some embodiments of the present application, Figure 6 As shown, the present application provides an electronic device 400, including: a processor 401 and a memory 402, the processor 401 and the memory 402 are interconnected and communicate with each other through a communication bus 403 and / or other forms of connection mechanisms (not shown), the memory 402 stores a computer program executable by the processor 401, and when the computing device is running, the processor 401 executes the computer program to execute a method executed by an external terminal in any optional implementation, for example: obtaining current change data of a battery to be tested that changes with time during a constant voltage charging stage; performing first-order differential processing on the current change data to obtain a dI / dt~t curve of the battery to be tested; according to a target time period formed by time points corresponding to each inflection point in the dI / dt~t curve, determining target current change data in the current change data that is in the target time period, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data.

[0094] The present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the method in any of the aforementioned optional implementations is executed.

[0095] Among them, the storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable red-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk.

[0096] The present application provides a computer program product. When the computer program product is run on a computer, the computer is enabled to execute the method in any optional implementation manner.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for detecting battery lithium deposition, characterized in that: The method comprises: Obtain the current change data of the battery under test during the constant voltage charging stage over time; Performing first-order differential processing on the current change data to obtain a dI / dt-t curve of the battery to be tested; According to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, the target current change data in the target time period is determined, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data.

2. The method according to claim 1, characterized in that The constant voltage charging stage is a period of time in which the battery to be tested is charged at a constant voltage when the battery to be tested is charged to a cut-off voltage.

3. The method according to claim 1, characterized in that Determining target current change data in the target time period in the current change data according to a target time period formed by time points corresponding to inflection points in the dI / dt-t curve includes: When it is determined that lithium deposition occurs in the battery to be tested according to the current change data, target current change data in the target time period is determined according to a target time period formed by time points corresponding to inflection points in the dI / dt~t curve.

4. The method according to claim 1, characterized in that: Determining target current change data in the target time period in the current change data according to a target time period formed by time points corresponding to inflection points in the dI / dt-t curve includes: When it is determined that the battery to be tested has lithium deposition according to the dI / dt~t curve, target current change data in the target time period is determined according to a target time period formed by time points corresponding to inflection points in the dI / dt~t curve.

5. The method according to claim 1, characterized in that Determining target current change data in the target time period in the current change data according to a target time period formed by time points corresponding to inflection points in the dI / dt-t curve includes: Performing high-order differential processing on the current change data to obtain a differential processing result corresponding to the current change data; When it is determined according to the differential processing result that lithium deposition occurs in the battery to be tested, target current change data in the target time period is determined according to a target time period formed by time points corresponding to inflection points in the dI / dt~t curve.

6. The method according to any one of claims 1 to 5, characterized in that: Obtaining the reversible lithium deposition amount of the battery to be tested according to the target current change data, including: Obtaining the reversible lithium deposition amount of the battery to be tested according to the current peak value in the target current change data and the reaction time corresponding to the current peak value; The reaction time corresponding to the current peak is determined according to the difference between the constant-voltage charging time corresponding to the current peak and the constant-voltage charging time corresponding to the first data point in the target current change data.

7. The method according to any one of claims 1 to 5, characterized in that: Obtaining the reversible lithium deposition amount of the battery to be tested according to the target current change data, including: According to the current value and reaction time corresponding to each data point in the target current change data, a function model representing the corresponding relationship between the current value and the reaction time is obtained; According to the time interval determined by the reaction time corresponding to each of the data points, the function model is integrated to obtain the reversible lithium deposition amount of the battery to be tested; The reaction time corresponding to any of the data points is determined according to the difference between the constant-voltage charging time corresponding to the data point and the constant-voltage charging time corresponding to the first data point in the target current change data.

8. The method according to any one of claims 1 to 5, characterized in that: The method further comprises: The irreversible lithium deposition amount of the battery under test is obtained according to the total lithium amount involved in charging of the battery under test during the constant voltage charging stage, the lithium capacity embedded in the anode of the battery under test during the constant voltage charging stage, and the reversible lithium deposition amount.

9. A battery lithium deposition detection device, characterized in that: The device comprises: The current data acquisition module is used to obtain the current change data of the battery under test that changes with time during the constant voltage charging stage; A current data processing module, used for performing first-order differential processing on the current change data to obtain a dI / dt-t curve of the battery to be tested; The battery lithium deposition detection module is used to determine the target current change data in the current change data that is in the target time period according to the target time period formed by the time points corresponding to the inflection points in the dI / dt~t curve, so as to obtain the reversible lithium deposition amount of the battery to be tested according to the target current change data.

10. An electronic device comprising a processor and a memory storing a computer program, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 8 is 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 method according to any one of claims 1 to 8 is implemented.

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