Method, device and equipment for detecting lithium precipitation amount of battery cell and storage medium

Abstract

The invention provides a method and device for detecting the lithium precipitation amount of a battery cell, electronic equipment and a computer readable storage medium, and the method comprises the steps: determining the health state and capacity loss information of a target battery cell according to the voltage capacity change of the target battery cell during the charging and discharging period of the target battery cell; the capacity loss information comprises first capacity loss information generated by the target battery cell due to lithium precipitation and second capacity loss information generated by the target battery cell due to a non-lithium precipitation factor; acquiring a sample cell in a non-lithium precipitation state, and constructing a preset mapping relation between the health state of the sample cell and the second capacity loss information of the sample cell; acquiring second capacity loss information of the target battery cell according to the health state of the target battery cell and a preset mapping relation; and determining first capacity loss information of the target battery cell according to the capacity loss information and the second capacity loss information of the target battery cell. According to the method, the lithium precipitation amount of the battery cell can be detected at low cost under the condition that the battery cell is not damaged.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and more specifically, to a method, device, electronic device and computer-readable storage medium for detecting the amount of lithium deposition in a battery cell in the field of battery technology. Background Art

[0002] Lithium plating in battery cells is one of the common failure problems currently faced in the industry. It is an important factor causing battery cell aging and safety issues. Therefore, detection and early warning of the lithium plating status of battery cells can provide a more comprehensive understanding of the health status of the battery cells, and help provide more flexible management and control methods for the battery cells, so as to achieve the purpose of extending the safe service life of the battery cells.

[0003] Regarding the lithium deposition status of the battery cell, on the one hand, the battery cell is currently disassembled to confirm, and the amount of lithium deposition is confirmed by physical property characterization, but this type of method is destructive testing and cannot be used directly as a means of monitoring the battery cell status. On the other hand, there are currently ultrasonic and electrochemical detection methods for non-destructive lithium deposition detection. Ultrasonic detection of lithium deposition requires an external probe and corresponding detection equipment. The cost of lithium deposition detection is high and it is not conducive to integration into small consumer terminals. Therefore, how to achieve low-cost battery cell lithium deposition detection without damaging the battery cell has become an urgent problem to be solved. Summary of the invention

[0004] The present application provides a method, device, electronic device and computer-readable storage medium for detecting the amount of lithium deposition in a battery cell. The method can detect the amount of lithium deposition in a battery cell at a low cost without causing damage to the battery cell.

[0005] In a first aspect, a method for detecting the amount of lithium deposition in a battery cell is provided, the method comprising: S10, during the charge and discharge period of the target battery cell, determining the target battery cell health state and the target battery cell capacity loss information according to the voltage-capacity change of the target battery cell; wherein the target battery cell capacity loss information comprises the target battery cell first capacity loss information caused by lithium deposition, and the target battery cell second capacity loss information caused by non-lithium deposition factors; S20, obtaining a sample battery cell in a non-lithium deposition state, and constructing a preset mapping relationship; wherein the preset mapping relationship comprises a mapping relationship between the sample battery cell health state and the sample battery cell second capacity loss information; S30, obtaining the target battery cell second capacity loss information according to the target battery cell health state and the preset mapping relationship; S40, determining the target battery cell first capacity loss information according to the target battery cell capacity loss information and the target battery cell second capacity loss information.

[0006] In combination with the first aspect, in some possible implementations, step S10 includes: performing constant current charging and discharging on the target battery cell to obtain the first operating condition parameter of the target battery cell, the first operating condition parameter of the target battery cell being the voltage and capacity of the target battery cell during charging and discharging; determining the health status of the target battery cell according to the battery cell design capacity of the target battery cell and the capacity in the first operating condition parameter of the target battery cell; constructing a first differential curve of the target battery cell according to the first operating condition parameter of the target battery cell; obtaining the second operating condition parameter of the target battery cell according to the open circuit voltage and the battery cell design capacity of the target battery cell; constructing a second differential curve of the target battery cell according to the second operating condition parameter of the target battery cell; and determining the capacity loss information of the target battery cell according to the first differential curve and the second differential curve of the target battery cell.

[0007] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, determining the target battery cell capacity loss information according to the first differential curve and the second differential curve of the target battery cell includes: obtaining the first low peak point in the first differential curve to obtain a first data point; obtaining the first low peak point in the second differential curve to obtain a second data point; determining the target battery cell capacity loss information according to the first data point and the second data point.

[0008] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, constant current charging and discharging of the target battery cell includes at least one of the following: a. obtaining the usage time of the target battery cell, and when the usage time reaches a preset time, using a preset current rate to perform constant current charging and discharging on the target battery cell; wherein the preset current rate includes a charging rate and a discharging rate; b. obtaining the historical number of cycle charge and discharge times of the target battery cell, and when the historical number of cycle charge and discharge times reaches a first preset number, using a preset current rate to perform constant current charging and discharging on the target battery cell.

[0009] In combination with the first aspect and the above-mentioned implementation manner, in some possible implementation manners, step S20 includes: during the charge and discharge period of the sample battery cell, determining the sample battery cell health state and the sample battery cell second capacity loss information caused by non-lithium plating factors according to the voltage-capacity change of the sample battery cell; constructing a preset mapping relationship according to the sample battery cell health state and the sample battery cell second capacity loss information; during the charge and discharge period of the sample battery cell, determining the sample battery cell health state and the sample battery cell second capacity loss information caused by non-lithium plating factors according to the voltage-capacity change of the sample battery cell includes: performing constant current charge and discharge on the sample battery cell to obtain a first operating condition parameter of the sample battery cell; wherein the first operating condition parameter of the sample battery cell is the voltage and capacity of the sample battery cell during the charge and discharge period; according to the battery design capacity of the sample battery cell and the first operating condition parameter of the sample battery cell The method comprises the following steps: determining the health state of the sample battery cell by using the capacity in the operating condition parameters; constructing a first differential curve of the sample battery cell according to the first operating condition parameters of the sample battery cell; obtaining the second operating condition parameters of the sample battery cell according to the open circuit voltage of the sample battery cell and the battery cell design capacity; constructing a second differential curve of the sample battery cell according to the second operating condition parameters of the sample battery cell; determining the second capacity loss information of the sample battery cell according to the first differential curve and the second differential curve of the sample battery cell; obtaining the first low peak point and the last low peak point in the first differential curve of the sample battery cell to obtain the third data point and the fourth data point; obtaining the first low peak point and the last low peak point in the second differential curve of the sample battery cell to obtain the fifth data point and the sixth data point; determining the second capacity loss information of the sample battery cell according to the third data point, the fourth data point, the fifth data point and the sixth data point.

[0010] In combination with the first aspect and the above implementations, in some possible implementations, the sample battery cells in a non-lithium deposition state must satisfy a capacity deviation between battery cells of <2% and a 50% SOC open circuit voltage deviation of <10mV.

[0011] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, the detection method also includes: comparing the first capacity loss information of the target battery cell and the preset capacity loss information; when the first capacity loss information of the target battery cell is greater than the preset capacity loss information, adjusting the charge and discharge strategy of the target battery cell to reduce the capacity loss of the target battery cell due to lithium plating.

[0012] In a second aspect, a device for detecting the amount of lithium deposition in a battery cell is provided, the device for detecting the amount of lithium deposition in a battery cell comprising:

[0013] A first calculation module is used to determine the health state of the target battery cell and the target battery cell capacity loss information according to the voltage-capacity change of the target battery cell during the charge and discharge period of the target battery cell; wherein the target battery cell capacity loss information includes the target battery cell first capacity loss information caused by lithium plating of the target battery cell, and the target battery cell second capacity loss information caused by non-lithium plating factors;

[0014] A mapping acquisition module is used to acquire a sample battery cell in a non-lithium deposition state and construct a preset mapping relationship; wherein the preset mapping relationship includes a mapping relationship between a sample battery cell health state and a sample battery cell second capacity loss information;

[0015] A second calculation module is used to obtain second capacity loss information of the target battery cell according to the health state of the target battery cell and a preset mapping relationship;

[0016] The third calculation module is used to determine the first capacity loss information of the target battery cell according to the target battery cell capacity loss information and the second capacity loss information of the target battery cell.

[0017] In conjunction with the second aspect, in some possible implementations, the first computing module includes:

[0018] A first acquisition unit is used to perform constant current charging and discharging on the target battery cell to acquire a first operating condition parameter of the target battery cell, where the first operating condition parameter of the target battery cell is a voltage and a capacity of the target battery cell during charging and discharging;

[0019] A first state calculation unit, used to determine a health state of the target battery cell according to a battery cell design capacity of the target battery cell and a capacity in a first operating condition parameter of the target battery cell;

[0020] A first curve construction unit, used to construct a first differential curve of the target battery cell according to a first operating condition parameter of the target battery cell;

[0021] A second acquisition unit, used for acquiring a second operating condition parameter of the target battery cell according to the open circuit voltage and the design capacity of the battery cell of the target battery cell;

[0022] A second curve construction unit, used to construct a second differential curve of the target battery cell according to a second operating condition parameter of the target battery cell;

[0023] The first information calculation unit is used to determine the target battery cell capacity loss information according to the first differential curve and the second differential curve of the target battery cell.

[0024] In combination with the second aspect and the foregoing implementation manner, in some possible implementation manners, the first information calculation unit includes:

[0025] The data point acquisition subunit is used to acquire the first low peak position in the first differential curve to obtain the first data point; acquire the first low peak position in the second differential curve to obtain the second data point;

[0026] The information calculation subunit is used to determine the target cell capacity loss information according to the first data point and the second data point.

[0027] In combination with the second aspect and the above implementation, in some possible implementations, the first acquisition unit includes performing constant current charging and discharging on the target battery cell, including:

[0028] The first charge and discharge electronic unit is used to obtain the usage time of the target battery cell, and when the usage time reaches a preset time, the target battery cell is charged and discharged at a constant current using a preset current rate; wherein the preset current rate includes a charge rate and a discharge rate;

[0029] The second charge and discharge electronic unit is used to obtain the historical charge and discharge cycle times of the target battery cell, and when the historical charge and discharge cycle times reach the first preset times, the target battery cell is charged and discharged at a constant current using a preset current rate.

[0030] In combination with the second aspect and the above implementations, in some possible implementations, the mapping acquisition module includes:

[0031] A second information calculation unit is used to determine the health status of the sample battery cell and the second capacity loss information of the sample battery cell caused by non-lithium plating factors according to the voltage-capacity change of the sample battery cell during the charging and discharging of the sample battery cell;

[0032] A mapping construction unit, used to construct a preset mapping relationship according to the health status of the sample battery cell and the second capacity loss information of the sample battery cell;

[0033] The second information calculation unit includes:

[0034] A first parameter acquisition subunit is used to perform constant current charging and discharging on the sample battery cell to obtain a first operating condition parameter of the sample battery cell; wherein the first operating condition parameter of the sample battery cell is the voltage and capacity of the sample battery cell during charging and discharging;

[0035] A first calculation subunit, used to determine the health state of the sample battery cell according to the battery cell design capacity of the sample battery cell and the capacity in the first operating condition parameter of the sample battery cell;

[0036] A first curve construction subunit, used to construct a first differential curve of the sample battery cell according to a first operating condition parameter of the sample battery cell;

[0037] A second parameter acquisition subunit, used to acquire a second operating condition parameter of the sample battery cell according to the open circuit voltage of the sample battery cell and the designed capacity of the battery cell;

[0038] A second curve construction subunit, used to construct a second differential curve of the sample battery cell according to a second operating condition parameter of the sample battery cell;

[0039] A data point acquisition subunit is used to acquire the first low peak position and the last low peak position in the first differential curve of the sample battery cell to obtain the third data point and the fourth data point; acquire the first low peak position and the last low peak position in the second differential curve of the sample battery cell to obtain the fifth data point and the sixth data point;

[0040] The second calculation subunit is used to determine second capacity loss information of the sample battery cell according to the third data point, the fourth data point, the fifth data point and the sixth data point.

[0041] In combination with the second aspect and the above implementations, in some possible implementations, the sample battery cells in a non-lithium deposition state must satisfy a capacity deviation between battery cells of <2% and a 50% SOC open circuit voltage deviation of <10mV.

[0042] In combination with the second aspect and the above implementation manner, in some possible implementation manners, the detection device further includes:

[0043] A comparing unit, used for comparing the first capacity loss information of the target battery cell with the preset capacity loss information;

[0044] The strategy adjustment unit is used to adjust the charge and discharge strategy of the target battery cell when the first capacity loss information of the target battery cell is greater than the preset capacity loss information, so as to reduce the capacity loss of the target battery cell caused by lithium plating.

[0045] In a third aspect, an electronic device is provided, comprising a memory and a processor. The memory is used to store executable program code, and the processor is used to call and run the executable program code from the memory, so that the electronic device executes the method for detecting the amount of lithium deposition in the battery cell in the first aspect or any possible implementation of the first aspect.

[0046] In a fourth aspect, a computer program product is provided, comprising: a computer program code, which, when executed on a computer, enables the computer to execute the method for detecting the amount of lithium deposition in a battery cell in the first aspect or any possible implementation of the first aspect.

[0047] In a fifth aspect, a computer-readable storage medium is provided, which stores a computer program code. When the computer program code runs on a computer, the computer executes the method for detecting the amount of lithium deposition in a battery cell in the first aspect or any possible implementation of the first aspect.

[0048] The method, device, electronic device and computer-readable storage medium for detecting the amount of lithium deposition in a battery cell provided in the embodiments of the present application have the following technical effects:

[0049] The technical solution provided by the embodiment of the present application determines the health status of the target battery cell and the target battery cell capacity loss information according to the voltage-capacity change of the target battery cell during the charge and discharge period of the target battery cell, and the target battery cell capacity loss information includes the first capacity loss information of the target battery cell caused by lithium precipitation, and the second capacity loss information of the target battery cell caused by non-lithium precipitation factors, and the first capacity loss information of the target battery cell is the amount of lithium precipitation of the target battery cell. Since the obtained target battery cell capacity loss information includes the amount of lithium precipitation and the second capacity loss information of the target battery cell, it is necessary to filter the second capacity loss information of the target battery cell from the target battery cell capacity loss information to obtain the amount of lithium precipitation. In order to avoid causing damage to the target battery cell, a sample battery cell in a non-lithium deposition state is obtained, thereby constructing a preset mapping relationship between the sample battery cell health state and the sample battery cell second capacity loss information. After obtaining the target battery cell health state, the preset mapping relationship is constructed by querying the target battery cell health state, thereby obtaining the target battery cell second capacity loss information without causing damage to the target battery cell, and then filtering the target battery cell second capacity loss information from the target battery cell capacity loss information. The information retained in the target battery cell capacity loss information is the amount of lithium deposition of the target battery cell, thereby realizing low-cost detection of the amount of lithium deposition of the battery cell without causing damage to the battery cell, thereby achieving the purpose of quantifying the amount of lithium deposition. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A schematic flow chart of a method for detecting the amount of lithium deposition in a battery cell provided in an embodiment of the present application is shown;

[0051] Figure 2 A schematic diagram showing a voltage-capacity differential curve;

[0052] Figure 3 A schematic diagram of the structure of a device for detecting the amount of lithium deposition in a battery cell provided in an embodiment of the present application is shown;

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

[0054] The technical solution in the present application will be described clearly and in detail below in conjunction with the accompanying drawings. In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B: "and / or" in the text is only a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0055] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as suggesting or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0056] Lithium deposition in battery cells is one of the most common failure problems in the industry. It has always been a concern in the industry. When the battery cell is used at low temperatures or at high temperatures for a long time, lithium deposition may occur. Even if it is cycled under normal conditions, the battery cell may fail due to lithium deposition when it is near the end of its life cycle. With the popularization of fast charging and discharging technology, how to ensure that the battery cell does not produce safety issues caused by lithium deposition during its use cycle has become a technical problem that major manufacturers focus on.

[0057] Lithium plating in battery cells is an important factor causing battery cell aging and safety issues. Therefore, detection and early warning of lithium plating status of battery cells can provide a more comprehensive understanding of the health status of battery cells and help provide more flexible management and control methods for battery cells, so as to achieve the purpose of extending the safe service life of battery cells.

[0058] Regarding the lithium deposition status of the battery cell, on the one hand, the battery cell is currently disassembled to confirm it, and the amount of lithium deposition is confirmed by physical property characterization, but this type of method is destructive testing and cannot be directly used as a means of monitoring the battery cell status. On the other hand, there are currently ultrasonic and electrochemical detection methods for non-destructive lithium deposition detection. Ultrasonic detection of lithium deposition requires an external probe and corresponding detection equipment. The cost of lithium deposition detection is high and it is not conducive to integration into small consumer terminals. On the other hand, electrochemical detection methods usually obtain the changing state of the reversible lithium in the battery cell through changes in voltage or internal resistance, thereby judging the lithium deposition status of the battery cell. The most harmful thing in the battery cell is dead lithium, and it is difficult to directly obtain information about dead lithium through electrochemical signals, so it is difficult to directly perform quantitative evaluation.

[0059] Therefore, in order to solve the technical problems existing in the detection of lithium deposition in battery cells in the related art, the present application provides a method, device, electronic device and computer-readable storage medium for detecting the amount of lithium deposition in battery cells, which can replace the current destructive detection method of lithium deposition in battery cells, and can be combined with the actual cycle application process to analyze the charge and discharge capacity of the battery cells, thereby identifying the capacity occupied by dead lithium, thereby achieving the purpose of quantifying the amount of lithium deposition, and realizing the low-cost detection of the amount of lithium deposition in the battery cells without causing damage to the battery cells.

[0060] The following is an embodiment of a method for detecting the amount of lithium deposition in a battery cell provided in an embodiment of the present application.

[0061] Figure 1 FIG. 1 is a schematic flow chart of a method for detecting the amount of lithium deposition in a battery cell provided in an embodiment of the present application. Figure 1 As shown, the method for detecting the amount of lithium deposition in a battery cell provided in an embodiment of the present application is applied to electronic devices, which are devices that require battery power, such as laptop computers, mobile phones, electric vehicles, and the like.

[0062] The above-mentioned method for detecting the amount of lithium deposition in the battery cell includes the following schemes:

[0063] S10, during the charge and discharge period of the target battery cell, determining the target battery cell health status and the target battery cell capacity loss information according to the voltage-capacity change of the target battery cell; wherein the target battery cell capacity loss information includes the target battery cell first capacity loss information caused by lithium plating of the target battery cell, and the target battery cell second capacity loss information caused by non-lithium plating factors.

[0064] The target cell can be understood as a cell that is put into practical application or a cell that is in the testing phase. For example, the target cell is a cell used in mobile phone B that user A has already purchased. The charging and discharging period of the target cell can be understood as the charging and discharging process of the target cell. During the charging and discharging period of the target cell, the voltage-capacity change of the target cell is obtained from an electrochemical perspective. The voltage-capacity change of the target cell can be represented by a curve of the cell voltage and cell capacity during the charging and discharging process of the target cell. After obtaining the voltage-capacity change of the target battery cell, the target battery cell health state and target battery cell capacity loss information Q1 are calculated according to the voltage-capacity change of the target battery cell. The target battery cell health state is called the target battery cell SOH (State of Health, SOH), Q1 includes the target battery cell first capacity loss information Qli caused by lithium plating, and the target battery cell second capacity loss information Q2 caused by non-lithium plating factors. Non-lithium plating factors can be understood as factors that cause capacity loss of the target battery cell other than lithium plating during the charge and discharge process of the target battery cell, such as aging loss of other materials in the target battery cell except lithium material loss.

[0065] S20, obtaining a sample battery cell in a non-lithium deposition state, and constructing a preset mapping relationship; wherein the preset mapping relationship includes a mapping relationship between a health state of the sample battery cell and second capacity loss information of the sample battery cell.

[0066] The sample cell can be understood as a cell that has been produced and does not have lithium deposition. A sample cell in a non-lithium deposition state is obtained. Since the sample cell does not have lithium deposition, the sample cell can be charged and discharged to obtain the sample cell SOH and the second capacity loss information of the sample cell caused by non-lithium deposition factors. The sample cell SOH and the second capacity loss information of the sample cell are associated to obtain a preset mapping relationship, thereby realizing the construction of the preset mapping relationship, that is, the preset mapping relationship is a mapping relationship between the sample cell SOH and the second capacity loss information of the sample cell. The sample cell includes multiple cells, and there are multiple sample cell SOHs and the second capacity loss information of the sample cell corresponding to each of the multiple sample cell SOHs in the preset mapping relationship.

[0067] S30, obtaining second capacity loss information of the target battery cell according to the target battery cell health state and a preset mapping relationship.

[0068] After obtaining the target cell SOH and the preset mapping relationship, the sample cell SOH that is the same as the target cell SOH is queried from the preset mapping relationship, so as to obtain the second capacity loss information of the sample cell corresponding to the sample cell SOH that is the same as the target cell SOH in the preset mapping relationship, that is, obtain Q2 corresponding to the target cell SOH. By querying the preset mapping relationship through the target cell SOH, Q2 corresponding to the target cell SOH can be quickly obtained, reducing the amount of data calculation.

[0069] S40, determining the first capacity loss information of the target battery cell according to the target battery cell capacity loss information and the second capacity loss information of the target battery cell.

[0070] After obtaining Q2, Q2 is filtered out from Q1 to obtain Qli, Qli=Q1-Q2, Qli is also called the lithium deposition amount of the target battery cell. Filtering Q2 out of Q1 can also be understood as correcting the lithium deposition amount, that is, excluding Q2 generated by non-lithium deposition factors in the target battery cell in Q1, thereby improving the accuracy of the calculation of the lithium deposition amount.

[0071] The technical solution provided by the embodiment of the present application determines the health status of the target battery cell and the target battery cell capacity loss information according to the voltage-capacity change of the target battery cell during the charge and discharge period of the target battery cell, and the target battery cell capacity loss information includes the first capacity loss information of the target battery cell caused by lithium precipitation, and the second capacity loss information of the target battery cell caused by non-lithium precipitation factors, and the first capacity loss information of the target battery cell is the amount of lithium precipitation of the target battery cell. Since the obtained target battery cell capacity loss information includes the amount of lithium precipitation and the second capacity loss information of the target battery cell, it is necessary to filter the second capacity loss information of the target battery cell from the target battery cell capacity loss information to obtain the amount of lithium precipitation. In order to avoid causing damage to the target battery cell, a sample battery cell in a non-lithium deposition state is obtained, thereby constructing a preset mapping relationship between the sample battery cell health state and the sample battery cell second capacity loss information. After obtaining the target battery cell health state, the preset mapping relationship is constructed by querying the target battery cell health state, thereby obtaining the target battery cell second capacity loss information without causing damage to the target battery cell, and then filtering the target battery cell second capacity loss information from the target battery cell capacity loss information. The information retained in the target battery cell capacity loss information is the amount of lithium deposition of the target battery cell, thereby realizing low-cost detection of the amount of lithium deposition of the battery cell without causing damage to the battery cell, thereby achieving the purpose of quantifying the amount of lithium deposition.

[0072] The following Figure 1 The specific implementation methods of each step in the illustrated embodiment are described as follows:

[0073] In a possible implementation, the above S10 includes the following solutions:

[0074] Performing constant current charging and discharging on the target battery cell to obtain a first operating condition parameter of the target battery cell, where the first operating condition parameter of the target battery cell is the voltage and capacity of the target battery cell during charging and discharging;

[0075] Determine the health state of the target battery cell according to the battery cell design capacity of the target battery cell and the capacity in the first operating condition parameter of the target battery cell;

[0076] Constructing a first differential curve of the target battery cell according to a first operating condition parameter of the target battery cell;

[0077] Obtaining a second operating condition parameter of the target battery cell according to the open circuit voltage of the target battery cell and the design capacity of the battery cell;

[0078] Constructing a second differential curve of the target battery cell according to a second operating condition parameter of the target battery cell;

[0079] The target battery cell capacity loss information is determined according to the first differential curve and the second differential curve of the target battery cell.

[0080] For the calculation of the target cell SOH and Q1, the target cell is first charged and discharged at a constant current. By charging and discharging the target cell at a constant current, it can be ensured that the acquired data is stable and accurate, and is not prone to mutation, which is conducive to improving the accuracy of the calculation of the target cell SOH and Q1. In the process of charging and discharging the target cell at a constant current, the first operating condition parameter of the target cell is obtained, that is, the first operating condition parameter of the target cell is the cell voltage and cell capacity during the charging and discharging of the target cell. Among them, the cell capacity refers to the current capacity of the target cell.

[0081] The target battery cell SOH is calculated through capacity calculation, that is, the ratio of the battery cell capacity in the first operating condition parameter of the target battery cell to the battery cell design capacity of the target battery cell is the target battery cell SOH.

[0082] Since the lithium ions in the battery cell are reduced to lithium monomers and deposited on the surface of the negative electrode particles, the reduction process requires power consumption. According to Faraday's law, the amount of lithium monomer generated corresponds to the amount of power consumed, so the amount of lithium deposition can be described by power. The power consumed by lithium deposition is also reflected in the capacity change of the battery cell and is part of the capacity loss of the battery cell. During the low-rate current charge and discharge process, the battery cell is less affected by polarization, and accurate voltage and capacity corresponding information can be obtained. By performing first-order differential processing on the voltage-capacity curve, the voltage-capacity differential curve is obtained. From the peak position shift and peak spacing change in the curve, the capacity change caused by lithium deposition can be obtained. In addition, considering that the normal cycle aging process of the battery cell will also produce capacity loss, this item needs to be corrected to finally obtain the capacity information corresponding to lithium deposition. The accuracy of the result is mainly affected by the acquisition rate, temperature and material system. Among them, performing first-order differential processing on the voltage-capacity curve to obtain the differential voltage-capacity curve is the prerequisite for capacity loss analysis. According to the differential voltage-capacity curve, the difference between capacity and voltage caused by thermodynamics can be distinguished, as well as the capacity loss corresponding to lithium loss and material attenuation can be distinguished.

[0083] For the calculation of Q1, the first curve of the target battery cell is constructed according to the first operating condition parameter of the target battery cell, that is, the first curve is the curve of the target battery cell with respect to the battery cell voltage-battery cell capacity, and the first curve is subjected to first-order differentiation to obtain the first differential curve of the target battery cell. Also, according to the open circuit voltage and the battery cell design capacity of the target battery cell, the second operating condition parameter of the target battery cell is obtained, that is, the second operating condition parameter of the target battery cell includes the open circuit voltage and the battery cell design capacity, and then the second curve of the target battery cell is constructed according to the second operating condition parameter of the target battery cell, that is, the second curve is the curve of the target battery cell with respect to the open circuit voltage-battery cell design capacity, and the second curve is subjected to first-order differentiation to obtain the second differential curve of the target battery cell. Figure 2 As shown, Figure 2 A schematic diagram showing the voltage-capacity differential curve, Figure 2 DVA1 represents the first differential curve of the target battery cell, DVA2 represents the second differential curve of the target battery cell, the horizontal and vertical axes represent the battery cell capacity, and the vertical axis represents the differential result of voltage and capacity. After obtaining the first differential curve and the second differential curve, the difference information between the first differential curve and the second differential curve is determined, thereby obtaining Q1 of the target battery cell.

[0084] In a possible implementation, the above-mentioned determination of the target battery cell capacity loss information according to the first differential curve and the second differential curve of the target battery cell includes the following scheme:

[0085] Obtaining the first low peak position in the first differential curve to obtain the first data point;

[0086] Obtaining the first low peak position in the second differential curve to obtain a second data point;

[0087] Target cell capacity loss information is determined according to the first data point and the second data point.

[0088] Since the characteristic point on the differential curve related to lithium precipitation is the first low peak point in the curve, such as Figure 2 As shown, after obtaining the first differential curve and the second differential curve, obtain the first low peak position in the first differential curve, that is, point A in the first differential curve, and use point A as the first data point; obtain the first low peak position in the second differential curve, that is, point A' in the second differential curve, and use point A' as the second data point, and then calculate the difference between the horizontal and vertical values ​​in the first data point and the horizontal and vertical values ​​in the second data point to obtain the difference information between the first differential curve and the second differential curve, that is, Q1 of the target battery cell. Figure 2 As shown, the peak point in the differential curve represents the phase change process of the material in the battery cell, the first data point represents the active lithium loss during the charge and discharge process of the target battery cell during normal use, and the second data point represents the active lithium loss during the charge and discharge process of the target battery cell at an open circuit voltage. Since the horizontal and vertical axes represent the capacity of the battery cell, the difference between the horizontal and vertical values ​​in the first data point and the horizontal and vertical values ​​in the second data point is calculated to obtain the Q1 of the target battery cell.

[0089] The Q1 calculated in the above manner is the Q1 corresponding to each charge and discharge of the target cell. For the subsequent multiple charge and discharge of the target cell, the calculation formula for Q1 corresponding to each subsequent charge and discharge is: Q1 = qn-q0, qn is the horizontal and vertical values ​​of the first data point on the first differential curve constructed for each charge and discharge of the target cell, and q0 is the horizontal and vertical values ​​of the second data point. For example, the target cell is charged and discharged three times in a cycle, Q1 = q1-q0 for the first charge and discharge, Q1 = q2-q0 for the second charge and discharge, and Q1 = q3-q0 for the third charge and discharge.

[0090] In a possible implementation, the constant current charging and discharging of the target battery cell includes at least one of the following:

[0091] a. Obtain the usage time of the target battery cell, and when the usage time reaches the preset time, use the preset current rate to perform constant current charging and discharging on the target battery cell; wherein the preset current rate includes the charging rate and the discharging rate;

[0092] b. Obtaining the historical charge and discharge cycle times of the target battery cell, and when the historical charge and discharge cycle times reach a first preset number, performing constant current charge and discharge on the target battery cell using a preset current rate.

[0093] During the actual use of the target battery cell, a trigger condition for detecting the amount of lithium deposition can be set for the target battery cell according to the actual use requirements. For example, if the ring use cycle of the target battery cell is reached, it means that the trigger condition for detecting the amount of lithium deposition is met. The ring use cycle of the target battery cell can be determined by the usage time of the target battery cell and / or the number of historical cycle charge and discharge times, where the number of historical cycle charge and discharge times is 1, indicating that the target battery cell has been charged and discharged once. If the usage time of the target battery cell reaches the preset time, it means that the ring use cycle of the target battery cell is reached, that is, the trigger condition for detecting the amount of lithium deposition is met, and the preset current rate is used to perform constant current charge and discharge on the target battery cell. If the number of historical cycle charge and discharge times of the target battery cell reaches the first preset number, it means that the ring use cycle of the target battery cell is reached, that is, the trigger condition for detecting the amount of lithium deposition is met, and the preset current rate is used to perform constant current charge and discharge on the target battery cell. Among them, since the battery cell is less affected by polarization during the low-rate current charging and discharging process, the preset current rate of the present application includes a charging rate and a discharging rate, and the charging rate and the discharging rate are both within the preset rate range, for example, the preset rate range is 0.1-0.3C, so that a smaller charging rate and a smaller discharging rate can be used to perform constant current charging and discharging on the target battery cell, reducing the polarization influence of the battery cell during the charging and discharging process, which is conducive to accurately obtaining the target battery cell voltage information and capacity information.

[0094] In a possible implementation, the above S20 includes the following solutions:

[0095] During the charge and discharge period of the sample battery cell, determining the health status of the sample battery cell and the second capacity loss information of the sample battery cell caused by non-lithium plating factors according to the voltage-capacity change of the sample battery cell;

[0096] A preset mapping relationship is constructed according to the sample battery cell health status and the sample battery cell second capacity loss information.

[0097] During the mass production stage of battery cells, multiple battery cells with very small differences in the non-lithium deposition state are selected from different batches of battery cells produced according to certain selection conditions to obtain sample battery cells, that is, there are multiple sample battery cells, for example, 20. Among them, the sample battery cells in the non-lithium deposition state must meet the requirements that the capacity deviation between the battery cells is <2%, and the 50% SOC open circuit voltage deviation is <10mV, which means that the difference between the multiple sample battery cells in the non-lithium deposition state is very small or even no difference. In addition, the sample battery cells in the non-lithium deposition state do not have lithium deposition, that is, there is no lithium deposition amount, then the first capacity loss information of the sample battery cell is 0. Among them, SOC is the state of charge, and its full English name is State of Charge.

[0098] After obtaining the sample battery, the normal use simulation of the sample battery is carried out according to the commonly used cycle temperature (e.g., 15-40 degrees Celsius) and small rate conditions (e.g., the charge rate and discharge rate are within the range of 0.5-2C), such as using the sample battery at intervals of a certain usage time or a certain number of cycles. Among them, using the sample battery at intervals of a certain usage time includes charging and discharging the sample battery; using the sample battery at intervals of a certain number of cycles can be understood as performing multiple constant current charge and discharge on the sample battery. When the number of cycles is 1, it means that the sample battery has been charged and discharged once.

[0099] During the charge and discharge of the sample cell, the voltage-capacity change of the sample cell is obtained from an electrochemical perspective. The voltage-capacity change of the sample cell can be represented by a differential curve of the cell voltage and cell capacity during the charge and discharge process of the sample cell. After obtaining the voltage-capacity change of the sample cell, the sample cell SOH and the second capacity loss information Q′2 of the sample cell caused by non-lithium deposition factors are calculated based on the voltage-capacity change of the sample cell.

[0100] Since there are multiple sample cells, the obtained sample cell SOH and Q′2 have multiple groups. Then, according to the multiple groups of sample cell SOH and Q′2 and the basic formula of the linear function, the slope and constant of the preset function are determined, and the slope and constant in the basic formula of the linear function are taken as unknowns. The basic formula is y=kx+b, k is the slope, and b is the constant. A system of equations is constructed by multiple groups of sample cell SOH and Q′2. After solving the system of equations, the slope and constant of the preset function are obtained. Then, a preset function is generated according to the obtained slope and constant, that is, a preset mapping relationship is obtained, that is, the preset mapping relationship is a linear function of the sample cell SOH and Q′2. After the preset mapping relationship is constructed, the preset mapping relationship is built into the battery management system of the target cell. The subsequent battery management system can periodically detect the amount of lithium deposition of the target cell without loss based on the preset mapping relationship.

[0101] In a possible implementation, during the charging and discharging period of the sample cell, determining the sample cell health status and the sample cell second capacity loss information caused by non-lithium deposition factors according to the voltage-capacity change of the sample cell includes the following scheme:

[0102] Performing constant current charging and discharging on the sample battery cell to obtain a first operating condition parameter of the sample battery cell; wherein the first operating condition parameter of the sample battery cell is the voltage and capacity of the sample battery cell during charging and discharging;

[0103] Determine the health status of the sample battery cell according to the battery cell design capacity of the sample battery cell and the capacity in the first operating condition parameter of the sample battery cell;

[0104] Constructing a first differential curve of the sample battery cell according to a first operating condition parameter of the sample battery cell;

[0105] Obtaining a second operating condition parameter of the sample battery cell according to the open circuit voltage of the sample battery cell and the design capacity of the battery cell;

[0106] Constructing a second differential curve of the sample battery cell according to the second operating condition parameter of the sample battery cell;

[0107] Obtaining a first low peak position and a last low peak position in a first differential curve of the sample battery cell to obtain a third data point and a fourth data point;

[0108] Obtaining the first low peak point and the last low peak point in the second differential curve of the sample battery cell to obtain the fifth data point and the sixth data point;

[0109] The second capacity loss information of the sample battery cell is determined according to the third data point, the fourth data point, the fifth data point and the sixth data point.

[0110] For the calculation of the SOH and Q′2 of the sample cell, the sample cell is first charged and discharged at a constant current. During the constant current charging and discharging of the sample cell, the first operating condition parameter of the sample cell is obtained, that is, the first operating condition parameter of the sample cell is the cell voltage and cell capacity during the charging and discharging of the sample cell. The cell capacity refers to the current capacity of the sample cell.

[0111] The SOH of the sample battery cell is calculated through capacity calculation, that is, the ratio of the battery cell capacity in the first operating condition parameter of the sample battery cell to the battery cell design capacity of the sample battery cell is the SOH of the sample battery cell.

[0112] For the calculation of Q′2, the third curve of the sample cell is constructed according to the first operating condition parameter of the sample cell, that is, the third curve is the curve of the sample cell about the cell voltage-cell capacity, and the third curve is subjected to first-order differential processing to obtain the first differential curve of the sample cell. Also, the second operating condition parameter of the sample cell is obtained according to the open circuit voltage and the cell design capacity of the sample cell, that is, the second operating condition parameter of the sample cell includes the open circuit voltage and the cell design capacity of the sample cell, and then the fourth curve of the sample cell is constructed according to the second operating condition parameter of the sample cell, that is, the fourth curve is the curve of the sample cell about the open circuit voltage-cell design capacity, and the fourth curve is subjected to first-order differential processing to obtain the second differential curve of the sample cell. Figure 2 As shown, Figure 2 DVA1 may also represent the first differential curve of the sample battery cell, and DVA2 may also represent the second differential curve of the sample battery cell.

[0113] like Figure 2 As shown, the peak position in the differential curve represents the phase change process of the material in the battery cell. The first low peak position A in the first differential curve of the sample battery cell is the third data point, and the last low peak position B is the fourth data point. The third data point represents the loss of active lithium in the charge and discharge process of the sample battery cell when simulating normal use. The fourth data point represents the phase change information of other materials other than lithium materials in the charge and discharge process of the sample battery cell when simulating normal use, such as the phase change information of graphite materials. The first low peak position A' in the second differential curve of the sample battery cell is the fifth data point, and the last low peak position B' is the sixth data point. The fifth data point represents the loss of active lithium in the charge and discharge process of the sample battery cell at an open circuit voltage. The sixth data point represents the phase change information of other materials other than lithium materials in the charge and discharge process of the sample battery cell at an open circuit voltage. After obtaining the third data point, the fourth data point, the fifth data point and the sixth data point, the difference between the horizontal and vertical values ​​in the third data point and the horizontal and vertical values ​​in the fourth data point is calculated to obtain the loss capacity of materials other than lithium materials in the charging and discharging process of the sample battery cell when simulating normal use, expressed as Q3; and the difference between the horizontal and vertical values ​​in the fifth data point and the horizontal and vertical values ​​in the sixth data point is calculated to obtain the loss capacity of materials other than lithium materials in the charging and discharging process of the sample battery cell at open circuit voltage, expressed as Q4, and then the difference between Q3 and Q4 is calculated to obtain Q′2 of the sample battery cell.

[0114] In a possible implementation, the above detection method further includes a solution:

[0115] Comparing the first capacity loss information of the target battery cell with the preset capacity loss information;

[0116] When the first capacity loss information of the target battery cell is greater than the preset capacity loss information, the charge and discharge strategy of the target battery cell is adjusted to reduce the capacity loss of the target battery cell caused by lithium plating.

[0117] After obtaining the first capacity loss information of the target battery cell, the first capacity loss information of the target battery cell is compared with the preset capacity loss information. If the first capacity loss information of the target battery cell is greater than the preset capacity loss information, it means that when the target battery cell is charged and discharged according to the currently set charge and discharge strategy, the amount of lithium precipitated in the target battery cell is too much, that is, the battery capacity loss of the target battery cell due to lithium precipitate is relatively serious. In this case, the charge and discharge strategy of the target battery cell is adjusted to reduce the capacity loss of the target battery cell due to lithium precipitate, which is beneficial to extend the service life of the target battery cell.

[0118] The following is an example of the implementation of the method for detecting the amount of lithium deposition in a battery cell provided by the present application, as follows:

[0119] Example 1. Identification of continuous lithium deposition during the cycling process of lithium cobalt manganese oxide ternary and graphite system batteries: Regarding the construction of a preset mapping relationship, the sample battery cell is a nickel cobalt manganese oxide ternary and graphite system battery cell. A nickel cobalt manganese oxide and graphite system battery with a capacity of 3500mAh is selected, and the charge and discharge voltage range is 2.8-4.25V. The temperature is 25 degrees Celsius and the current rate is 2C for charging and 0.5C for discharging. The battery cell is cycled for 600 cycles, the capacity information is collected, and the capacity change of the battery cell is recorded. The battery cell is charged and discharged at a current rate of 0.1C every 100 cycles. At the same time, the capacity and voltage data at a current rate of 0.1C are collected to construct a voltage-capacity curve, and the voltage-capacity curve is first-order differentiated to obtain a voltage-capacity differential curve. The preset mapping relationship is constructed according to the voltage-capacity differential curve, and the preset mapping relationship is Q2=-41.32*SOH+41.28.

[0120] After obtaining the preset mapping relationship, for the target cell of the same model as the sample cell, the capacity of the target cell is 3500mAh, and the target cell is monitored under its designed application conditions (charging with a current rate of 1.5C and discharging with a current rate of 4C), and the lithium deposition amount of the target cell is cycled at 25 degrees Celsius and in the voltage range of 2.8-4.25V. The lithium deposition amount is detected every 50 cycles, and each detection uses a current rate of 0.2C to charge and discharge at 25 degrees Celsius and obtain voltage-capacity data, and the lithium deposition amount Qli is further calculated in combination with the target cell SOH and the preset mapping relationship. The lithium deposition amount Qli obtained in each round of 650 cycles is shown in Table 1 below, where Qli is ignored when it is less than 2mAh:

[0121] Table 1: Lithium deposition in each test for 650 cycles

[0122] Number of cycles Q1 SOH(%) Q2 Lithium deposition capacity Qli (mAh) 100 10.8 97.5 11.7 / 150 11.2 96.6 12.0 / 200 11.7 95.7 12.3 / 250 11.9 95.3 12.4 / 300 12.4 94.7 12.6 / 350 12.7 94.4 12.7 / 400 13.3 94.1 12.7 / 450 13.9 93.8 12.8 / 500 15.4 93.5 12.9 2.5 550 19.1 93.1 13.1 6.0 600 21.6 92.7 13.2 8.4 650 64.3 91.5 13.5 50.8

[0123] From Table 1, we can see that lithium deposition gradually begins in the target battery cell from the 500th cycle, and the amount of lithium deposition gradually increases from 500 to 650 cycles, and the capacity corresponding to lithium deposition reaches 50.8 mAh at 650 cycles, that is, the capacity loss of the target battery cell due to lithium deposition reaches 50.8 mAh at 650 cycles.

[0124] Example 2: Identification of low-temperature lithium deposition during the cycling of nickel-cobalt-manganese-lithium ternary and graphite system batteries: The above preset mapping relationship and target battery have not changed. The target battery is charged at a current rate of 1.5C and discharged at a current rate of 2C. The cycle is performed within the voltage range of 2.8-4.25V. The cycle temperature for the first 500 cycles is 25 degrees Celsius. The cycle temperature for the 501st-650th cycles is reduced to 10 degrees Celsius. The lithium deposition amount is detected every 50 cycles, and each detection uses a current rate of 0.1C for charging and discharging. The lithium deposition amount Qli obtained for 650 cycles in each round is shown in Table 2 below, where Qli is ignored when it is less than 2mAh:

[0125] Table 2: Lithium deposition in each test for 650 cycles

[0126] Number of cycles Q1 SOH(%) Q2 Lithium deposition capacity Qli (mAh) 100 9.7 99.1 11.2 / 150 10.1 98.3 11.5 / 200 10.6 97.4 11.7 / 250 10.9 97.1 11.8 / 300 11.2 96.3 12.1 / 350 11.4 96.1 12.1 / 400 11.7 95.7 12.3 / 450 11.8 95.6 12.3 / 500 15.5 95.3 12.4 3.1 550 75.5 93.8 12.8 62.7 600 76.8 93.4 13.0 63.8 650 80.1 93.1 13.1 67.0

[0127] From Table 2, we can see that: from the results of lithium deposition of the target battery, the amount of lithium deposition in the first 500 cycles was not detected or was very low, and it can be considered that no significant lithium deposition occurred. After switching the cycle temperature to 10 degrees Celsius, the detection results of the 550th cycle showed that lithium deposition had begun to occur. After 50 cycles of cooling, the capacity loss corresponding to lithium deposition in the target battery reached 62.7mAh. Based on this information, from the 551th cycle, the charging current rate was reduced to 0.5C, and the discharge current rate was reduced to 1C before continuing the cycle. The test results of the 600th and 650th cycles show that after reducing the circulating current, the amount of lithium deposition of the target battery cell is controlled within a certain range. The amount of lithium deposition is 67mAh at the 650th cycle, compared with the lithium deposition amount of 59.6mAh at the initial stage of the cooling cycle (501-550 cycles). After the lithium deposition state is discovered and the current is reduced, the amount of lithium deposition increases by only 4.3mAh from the 551st to the 650th cycle. The lithium deposition of the target battery cell is effectively controlled, that is, the charge and discharge strategy of the target battery is adjusted to reduce the charging current rate of the target battery at low temperature, thereby reducing the capacity loss of the target battery cell due to lithium deposition.

[0128] The following is an embodiment of the device of the present application, which can be used to execute the embodiment of the method of the present application. For details not disclosed in the embodiment of the device of the present application, please refer to the embodiment of the method of the present application.

[0129] Figure 3The schematic diagram of the structure of a device for detecting the amount of lithium deposition in a battery cell provided in an embodiment of the present application is shown. Figure 3 As shown, the detection device 300 for detecting the amount of lithium deposition in the battery cell includes:

[0130] The first calculation module 310 is used to determine the health state of the target battery cell and the target battery cell capacity loss information according to the voltage-capacity change of the target battery cell during the charge and discharge period of the target battery cell; wherein the target battery cell capacity loss information includes the target battery cell first capacity loss information caused by lithium plating of the target battery cell, and the target battery cell second capacity loss information caused by non-lithium plating factors;

[0131] A mapping acquisition module 320 is used to acquire a sample battery cell in a non-lithium deposition state and construct a preset mapping relationship; wherein the preset mapping relationship includes a mapping relationship between a sample battery cell health state and a sample battery cell second capacity loss information;

[0132] A second calculation module 330 is used to obtain second capacity loss information of the target battery cell according to the target battery cell health state and a preset mapping relationship;

[0133] The third calculation module 340 is used to determine the target battery cell first capacity loss information according to the target battery cell capacity loss information and the target battery cell second capacity loss information.

[0134] In a possible implementation, the first calculation module 310 includes:

[0135] A first acquisition unit is used to perform constant current charging and discharging on the target battery cell to acquire a first operating condition parameter of the target battery cell, where the first operating condition parameter of the target battery cell is a voltage and a capacity of the target battery cell during charging and discharging;

[0136] A first state calculation unit, used to determine a health state of the target battery cell according to a battery cell design capacity of the target battery cell and a capacity in a first operating condition parameter of the target battery cell;

[0137] A first curve construction unit, used to construct a first differential curve of the target battery cell according to a first operating condition parameter of the target battery cell;

[0138] A second acquisition unit, used for acquiring a second operating condition parameter of the target battery cell according to the open circuit voltage and the design capacity of the battery cell of the target battery cell;

[0139] A second curve construction unit, used to construct a second differential curve of the target battery cell according to a second operating condition parameter of the target battery cell;

[0140] The first information calculation unit is used to determine the target battery cell capacity loss information according to the first differential curve and the second differential curve of the target battery cell.

[0141] In a possible implementation, the first information computing unit includes:

[0142] The data point acquisition subunit is used to acquire the first low peak position in the first differential curve to obtain the first data point; acquire the first low peak position in the second differential curve to obtain the second data point;

[0143] The information calculation subunit is used to determine the target cell capacity loss information according to the first data point and the second data point.

[0144] In a possible implementation, the first acquisition unit includes performing constant current charging and discharging on the target battery cell, including:

[0145] The first charge and discharge electronic unit is used to obtain the usage time of the target battery cell, and when the usage time reaches a preset time, the target battery cell is charged and discharged at a constant current using a preset current rate; wherein the preset current rate includes a charge rate and a discharge rate;

[0146] The second charge and discharge electronic unit is used to obtain the historical charge and discharge cycle times of the target battery cell, and when the historical charge and discharge cycle times reach the first preset times, the target battery cell is charged and discharged at a constant current using a preset current rate.

[0147] In a possible implementation, the mapping acquisition module 320 includes:

[0148] A second information calculation unit is used to determine the health status of the sample battery cell and the second capacity loss information of the sample battery cell caused by non-lithium plating factors according to the voltage-capacity change of the sample battery cell during the charging and discharging of the sample battery cell;

[0149] A mapping construction unit, used to construct a preset mapping relationship according to the health status of the sample battery cell and the second capacity loss information of the sample battery cell;

[0150] The second information calculation unit includes:

[0151] A first parameter acquisition subunit is used to perform constant current charging and discharging on the sample battery cell to obtain a first operating condition parameter of the sample battery cell; wherein the first operating condition parameter of the sample battery cell is the voltage and capacity of the sample battery cell during charging and discharging;

[0152] A first calculation subunit, used to determine the health state of the sample battery cell according to the battery cell design capacity of the sample battery cell and the capacity in the first operating condition parameter of the sample battery cell;

[0153] A first curve construction subunit, used to construct a first differential curve of the sample battery cell according to a first operating condition parameter of the sample battery cell;

[0154] A second parameter acquisition subunit, used to acquire a second operating condition parameter of the sample battery cell according to the open circuit voltage of the sample battery cell and the designed capacity of the battery cell;

[0155] A second curve construction subunit, used to construct a second differential curve of the sample battery cell according to a second operating condition parameter of the sample battery cell;

[0156] A data point acquisition subunit is used to acquire the first low peak position and the last low peak position in the first differential curve of the sample battery cell to obtain the third data point and the fourth data point; acquire the first low peak position and the last low peak position in the second differential curve of the sample battery cell to obtain the fifth data point and the sixth data point;

[0157] The second calculation subunit is used to determine second capacity loss information of the sample battery cell according to the third data point, the fourth data point, the fifth data point and the sixth data point.

[0158] In one possible implementation, the sample battery cells in the non-lithium deposition state must meet the requirements that the capacity deviation between the battery cells is less than 2% and the 50% SOC open circuit voltage deviation is less than 10mV.

[0159] In a possible implementation, the device 300 for detecting the amount of lithium deposition in a battery cell further includes:

[0160] A comparing unit, used for comparing the first capacity loss information of the target battery cell with the preset capacity loss information;

[0161] The strategy adjustment unit is used to adjust the charge and discharge strategy of the target battery cell when the first capacity loss information of the target battery cell is greater than the preset capacity loss information, so as to reduce the capacity loss of the target battery cell caused by lithium plating.

[0162] It should be noted that the device for detecting the amount of lithium deposition in a battery cell provided in the above-mentioned embodiment only uses the division of the above-mentioned functional modules as an example when executing the method for detecting the amount of lithium deposition in a battery cell. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the device for detecting the amount of lithium deposition in a battery cell provided in the above-mentioned embodiment and the embodiment of the method for detecting the amount of lithium deposition in a battery cell belong to the same concept. Therefore, for details not disclosed in the embodiment of the device of the present application, please refer to the embodiment of the method for detecting the amount of lithium deposition in a battery cell of the present application, which will not be repeated here.

[0163] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0164] Figure 4 A schematic structural diagram of an electronic device provided in an embodiment of the present application is shown.

[0165] For example, Figure 4 As shown, the electronic device 400 includes: a memory 401 and a processor 402, wherein the memory 401 stores an executable program code 4011, and the processor 402 is used to call and execute the executable program code 4011 to perform a method for detecting the amount of lithium deposition in a battery cell.

[0166] In this embodiment, the electronic device can be divided into functional modules according to the above method example. For example, each functional module can be corresponded to, or two or more functions can be integrated into one processing module. The above integrated module can be implemented in the form of hardware. It should be noted that the division of modules in this embodiment is schematic and is only a logical function division. There may be other division methods in actual implementation.

[0167] In the case of dividing each functional module according to each function, the electronic device may include: a first calculation module, a mapping acquisition module, a mapping acquisition module, a third calculation module, etc. It should be noted that all relevant contents of each step involved in the above method embodiment can be referred to the functional description of the corresponding functional module, which will not be repeated here.

[0168] The electronic device provided in this embodiment is used to execute the above-mentioned method for detecting the amount of lithium deposition in a battery cell, and thus can achieve the same effect as the above-mentioned implementation method.

[0169] In the case of an integrated unit, the electronic device may include a processing module and a storage module. The processing module may be used to control and manage the actions of the electronic device. The storage module may be used to support the electronic device in executing mutual program codes and data.

[0170] The processing module may be a processor or a controller, which may implement or execute various exemplary logic blocks, modules and circuits disclosed in the present application. The processor may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc. The storage module may be a memory.

[0171] This embodiment also provides a computer-readable storage medium, in which a computer program code is stored. When the computer program code is executed on a computer, the computer executes the above-mentioned related method steps to implement a method for detecting the amount of lithium deposition in a battery cell in the above-mentioned embodiment.

[0172] This embodiment further provides a computer program product. When the computer program product is run on a computer, the computer is caused to execute the above-mentioned related steps to implement a method for detecting the amount of lithium deposition in a battery cell in the above-mentioned embodiment.

[0173] In addition, the electronic device provided in the embodiments of the present application may specifically be a chip, a component or a module, and the electronic device may include a connected processor and a memory; wherein the memory is used to store instructions, and when the electronic device is running, the processor may call and execute instructions so that the chip executes a method for detecting the amount of lithium deposition in a battery cell in the above-mentioned embodiments.

[0174] Among them, the electronic device, computer-readable storage medium, computer program product or chip provided in this embodiment is used to execute the corresponding battery cell lithium deposition amount detection method provided above. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects in the corresponding battery cell lithium deposition amount detection method provided above, and will not be repeated here.

[0175] Through the description of the above implementation methods, technical personnel in the relevant field can understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0176] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0177] The above contents are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for detecting the amount of lithium deposition in a battery cell, characterized in that: The detection method comprises the steps of: S10, during the charge and discharge period of the target battery cell, determining the target battery cell health state and the target battery cell capacity loss information according to the voltage-capacity change of the target battery cell; wherein the target battery cell capacity loss information includes the target battery cell first capacity loss information caused by lithium plating of the target battery cell, and the target battery cell second capacity loss information caused by non-lithium plating factors; S20, obtaining a sample battery cell in a non-lithium deposition state, and constructing a preset mapping relationship; wherein the preset mapping relationship includes a mapping relationship between a health state of the sample battery cell and second capacity loss information of the sample battery cell; S30, acquiring second capacity loss information of the target battery cell according to the target battery cell health state and the preset mapping relationship; S40, determining the target battery cell first capacity loss information according to the target battery cell capacity loss information and the target battery cell second capacity loss information.

2. The detection method according to claim 1, characterized in that: The step S10 includes: Performing constant current charging and discharging on the target battery cell to obtain a first operating condition parameter of the target battery cell, where the first operating condition parameter of the target battery cell is a voltage and a capacity of the target battery cell during charging and discharging; Determining the health state of the target battery cell according to the battery cell design capacity of the target battery cell and the capacity in the first operating condition parameter of the target battery cell; Constructing a first differential curve of the target battery cell according to a first operating condition parameter of the target battery cell; Acquire a second operating condition parameter of the target battery cell according to the open circuit voltage of the target battery cell and the designed capacity of the battery cell; constructing a second differential curve of the target battery cell according to a second operating condition parameter of the target battery cell; The target battery cell capacity loss information is determined according to the first differential curve and the second differential curve of the target battery cell.

3. The detection method according to claim 2, characterized in that: The determining the target battery cell capacity loss information according to the first differential curve and the second differential curve of the target battery cell comprises: Acquire a first low peak position in the first differential curve to obtain a first data point; Obtaining a first low peak position in the second differential curve to obtain a second data point; The target cell capacity loss information is determined according to the first data point and the second data point.

4. The detection method according to claim 2, characterized in that: The constant current charging and discharging of the target battery cell includes at least one of the following: a. Obtaining the usage time of the target battery cell, and when the usage time reaches a preset time, using a preset current rate to perform constant current charging and discharging on the target battery cell; wherein the preset current rate includes a charging rate and a discharging rate; b. Obtaining the historical number of charge and discharge cycles of the target battery cell, and when the historical number of charge and discharge cycles reaches a first preset number, performing constant current charge and discharge on the target battery cell using the preset current rate.

5. The detection method according to claim 1, characterized in that: The step S20 includes: During the charging and discharging of the sample battery cell, determining the health status of the sample battery cell and the second capacity loss information of the sample battery cell caused by non-lithium plating factors according to the voltage-capacity change of the sample battery cell; Constructing the preset mapping relationship according to the sample battery cell health status and the sample battery cell second capacity loss information; During the charging and discharging of the sample battery cell, determining the health status of the sample battery cell and the second capacity loss information of the sample battery cell caused by non-lithium plating factors according to the voltage-capacity change of the sample battery cell includes: Performing constant current charging and discharging on the sample battery cell to obtain a first operating condition parameter of the sample battery cell; wherein the first operating condition parameter of the sample battery cell is the voltage and capacity of the sample battery cell during charging and discharging; Determining the health status of the sample battery cell according to the battery cell design capacity of the sample battery cell and the capacity in the first operating condition parameter of the sample battery cell; Constructing a first differential curve of the sample battery cell according to a first operating condition parameter of the sample battery cell; Acquire a second operating condition parameter of the sample battery cell according to the open circuit voltage of the sample battery cell and the designed capacity of the battery cell; constructing a second differential curve of the sample battery cell according to a second operating condition parameter of the sample battery cell; Obtaining a first low peak point and a last low peak point in the first differential curve of the sample battery cell to obtain a third data point and a fourth data point; Obtaining a first low peak point and a last low peak point in the second differential curve of the sample battery cell to obtain a fifth data point and a sixth data point; The second capacity loss information of the sample battery cell is determined according to the third data point, the fourth data point, the fifth data point and the sixth data point.

6. The detection method according to claim 1, characterized in that: The sample battery cells in the non-lithium deposition state must meet the requirements of a capacity deviation of less than 2% between battery cells and a 50% SOC open circuit voltage deviation of less than 10mV.

7. The detection method according to claim 1, characterized in that: The detection method further comprises: Comparing the first capacity loss information of the target battery cell with the preset capacity loss information; When the first capacity loss information of the target battery cell is greater than the preset capacity loss information, the charge and discharge strategy of the target battery cell is adjusted to reduce the capacity loss of the target battery cell caused by lithium plating.

8. A device for detecting the amount of lithium deposition in a battery cell, characterized in that: The detection device comprises: A first calculation module is used to determine the target battery cell health state and target battery cell capacity loss information according to the voltage-capacity change of the target battery cell during the charge and discharge period of the target battery cell; wherein the target battery cell capacity loss information includes the target battery cell first capacity loss information caused by lithium plating of the target battery cell, and the target battery cell second capacity loss information caused by non-lithium plating factors; A mapping acquisition module, used to acquire a sample battery cell in a non-lithium deposition state and construct a preset mapping relationship; wherein the preset mapping relationship includes a mapping relationship between a sample battery cell health state and a sample battery cell second capacity loss information; A second calculation module, used for obtaining the second capacity loss information of the target battery cell according to the target battery cell health state and the preset mapping relationship; The third calculation module is used to determine the first capacity loss information of the target battery cell according to the target battery cell capacity loss information and the second capacity loss information of the target battery cell.

9. An electronic device, characterized in that: The electronic device comprises: A memory for storing executable program codes; A processor, used to call and run the executable program code from the memory, so that the electronic device executes the method for detecting the amount of lithium deposition in the battery cell as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed, the method for detecting the amount of lithium deposition in a battery cell as claimed in any one of claims 1 to 7 is implemented.

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