Lithium precipitation nucleation negative electrode potential determination method, device, equipment, medium and product

Abstract

The invention relates to a lithium precipitation nucleation negative electrode potential determination method, device and equipment, a medium and a product, and the method comprises the steps: obtaining a plurality of electrode potentials of a working electrode of a test battery in the discharge process of the test battery for each test environment; the test battery is constructed by utilizing the negative electrode of the target lithium ion battery and a metal lithium sheet; the working electrode is an electrode corresponding to the negative electrode of the target lithium ion battery; determining the minimum value in the plurality of electrode potentials corresponding to each test environment as a target electrode potential; performing equation parameter fitting by using the target electrode potential in each test environment to obtain a corresponding relation between the lithium precipitation nucleation negative electrode potential and the charging current in each test environment; therefore, the battery management system can conveniently determine the corresponding lithium precipitation nucleation cathode potential in real time according to the charging environment in the charging process of the target lithium ion battery, so as to control the charging current, thereby ensuring the service life and performance of the lithium ion battery.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a method, apparatus, equipment, medium, and product for determining the negative electrode potential for lithium nucleation. Background Technology

[0002] During the charging process of lithium-ion batteries, improper charging steps can cause lithium plating at the negative electrode of the battery. Lithium plating not only affects the charging and discharging efficiency and cycle life of the battery, but may also cause internal short circuits in the battery, posing serious safety hazards.

[0003] Therefore, accurately determining the potential at which lithium plating begins on the negative electrode (i.e., the lithium nucleation potential of the negative electrode) is of great significance for optimizing the charging strategy of lithium-ion batteries and improving battery safety. Summary of the Invention

[0004] Therefore, it is necessary to provide a method, apparatus, equipment, medium, and product for determining the negative electrode potential of lithium nucleation in order to address the above-mentioned technical problems.

[0005] In a first aspect, this application provides a method for determining the nucleation potential of a lithium plating negative electrode, the method comprising:

[0006] For each test environment, during the discharge process of the test battery, multiple electrode potentials of the working electrode of the test battery are acquired; the test battery is constructed using the negative electrode of the target lithium-ion battery and a lithium metal sheet; the working electrode is the electrode corresponding to the negative electrode of the target lithium-ion battery; the ratio of the charging current of the target lithium-ion battery to the discharging current of the test battery is equal to the ratio of the capacity of the target lithium-ion battery to the capacity of the test battery.

[0007] The minimum value among multiple electrode potentials corresponding to each test environment is determined as the target electrode potential;

[0008] By fitting the equation parameters using the target electrode potential under each test environment, the corresponding relationship between the lithium nucleation negative electrode potential and the charging current under each test environment is obtained.

[0009] In one embodiment, the target electrode potential under each test environment is used to fit the equation parameters to obtain the correspondence between the lithium nucleation negative electrode potential and the charging current under each test environment, including:

[0010] For each test environment, the equation parameters are fitted using the target electrode potential and the mechanism equation of the lithium plating nucleation process to obtain the corresponding relationship between the lithium plating nucleation negative electrode potential and the charging current under each test environment.

[0011] In one embodiment, the mechanistic equation for the lithium plating nucleation process includes: ,in, To test the battery's discharge current; This is the negative electrode potential for lithium nucleation. These are the first fitted parameters; is the second fitting parameter.

[0012] In one embodiment, the mechanistic equation for the lithium plating nucleation process includes: ,in, To test the battery's discharge current; This is the negative electrode potential for lithium nucleation. These are the first fitted parameters; is the second fitting parameter.

[0013] In one embodiment, the method further includes:

[0014] Obtain the historical discharge rate and historical discharge temperature of the sample lithium-ion battery during its historical charging process; the sample lithium-ion battery is of the same type as the target lithium-ion battery.

[0015] Mesh partitioning is performed based on historical discharge rates and historical discharge temperatures to construct each test environment.

[0016] In one embodiment, the method further includes;

[0017] Determine the charging environment for the target lithium-ion battery;

[0018] Based on the charging environment, the target correspondence with the charging environment is determined from the correspondence between the lithium nucleation negative electrode potential and the charging current under each test environment.

[0019] The target lithium-ion battery is charged using the target correspondence relationship.

[0020] Secondly, this application also provides a device for determining the nucleation potential of lithium plating anode, the device comprising:

[0021] The potential data acquisition module is used to acquire multiple electrode potentials of the working electrode of the test battery during the discharge process of the test battery for each test environment; the test battery is constructed using the negative electrode of the target lithium-ion battery and a lithium metal sheet; the working electrode is the electrode corresponding to the negative electrode of the target lithium-ion battery; the ratio of the charging current of the target lithium-ion battery to the discharging current of the test battery is equal to the ratio of the capacity of the target lithium-ion battery to the capacity of the test battery.

[0022] The target potential determination module is used to determine the minimum value among multiple electrode potentials corresponding to each test environment as the target electrode potential.

[0023] The correspondence determination module is used to fit the equation parameters using the target electrode potential under each test environment, and obtain the correspondence between the lithium nucleation negative electrode potential and the charging current under each test environment.

[0024] Thirdly, this application also provides a computer device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0025] For each test environment, during the discharge process of the test battery, multiple electrode potentials of the working electrode of the test battery are acquired; the test battery is constructed using the negative electrode of the target lithium-ion battery and a lithium metal sheet; the working electrode is the electrode corresponding to the negative electrode of the target lithium-ion battery; the ratio of the charging current of the target lithium-ion battery to the discharging current of the test battery is equal to the ratio of the capacity of the target lithium-ion battery to the capacity of the test battery.

[0026] The minimum value among multiple electrode potentials corresponding to each test environment is determined as the target electrode potential;

[0027] By fitting the equation parameters using the target electrode potential under each test environment, the corresponding relationship between the lithium nucleation negative electrode potential and the charging current under each test environment is obtained.

[0028] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0029] For each test environment, during the discharge process of the test battery, multiple electrode potentials of the working electrode of the test battery are acquired; the test battery is constructed using the negative electrode of the target lithium-ion battery and a lithium metal sheet; the working electrode is the electrode corresponding to the negative electrode of the target lithium-ion battery; the ratio of the charging current of the target lithium-ion battery to the discharging current of the test battery is equal to the ratio of the capacity of the target lithium-ion battery to the capacity of the test battery.

[0030] The minimum value among multiple electrode potentials corresponding to each test environment is determined as the target electrode potential;

[0031] By fitting the equation parameters using the target electrode potential under each test environment, the corresponding relationship between the lithium nucleation negative electrode potential and the charging current under each test environment is obtained.

[0032] Fifthly, this application also provides a computer program product comprising a computer program that, when executed by a processor, performs the following steps:

[0033] For each test environment, during the discharge process of the test battery, multiple electrode potentials of the working electrode of the test battery are acquired; the test battery is constructed using the negative electrode of the target lithium-ion battery and a lithium metal sheet; the working electrode is the electrode corresponding to the negative electrode of the target lithium-ion battery; the ratio of the charging current of the target lithium-ion battery to the discharging current of the test battery is equal to the ratio of the capacity of the target lithium-ion battery to the capacity of the test battery.

[0034] The minimum value among multiple electrode potentials corresponding to each test environment is determined as the target electrode potential;

[0035] By fitting the equation parameters using the target electrode potential under each test environment, the corresponding relationship between the lithium nucleation negative electrode potential and the charging current under each test environment is obtained.

[0036] The aforementioned method, apparatus, equipment, medium, and product for determining the lithium nucleation negative electrode potential first acquire multiple electrode potentials of the working electrode of the test battery during the discharge process of the test battery, for each test environment; the test battery is constructed using the negative electrode of the target lithium-ion battery and a lithium metal sheet; the working electrode is the electrode corresponding to the negative electrode of the target lithium-ion battery; the ratio of the charging current of the target lithium-ion battery to the discharging current of the test battery is equal to the ratio of the capacity of the target lithium-ion battery to the capacity of the test battery; then, the minimum value among the multiple electrode potentials corresponding to each test environment is determined as the target electrode potential; then... By fitting the equation parameters using the target electrode potential under each test environment, the correspondence between the lithium plating nucleation negative electrode potential and the charging current under each test environment is obtained. This helps the target lithium-ion battery to determine the corresponding lithium plating nucleation negative electrode potential in real time according to the charging environment during the charging process. This allows the battery management system to control the charging current of the target lithium-ion battery based on the current lithium plating nucleation negative electrode potential, thereby ensuring the charging efficiency of the lithium-ion battery while preventing lithium plating at the negative electrode, thus guaranteeing the lifespan and performance of the lithium-ion battery. Attached Figure Description

[0037] Figure 1 A flowchart illustrating a method for determining the nucleation negative electrode potential for lithium plating provided in some embodiments of this application;

[0038] Figure 2 Flowcharts for building a test environment provided for some embodiments of this application;

[0039] Figure 3 Flowcharts for determining target correspondences provided in some embodiments of this application;

[0040] Figure 4 This is a measurement curve of the lithium nucleation negative electrode potential of the test battery at 0°C and 1C discharge rate in one embodiment of this application;

[0041] Figure 5 A graph showing the lithium nucleation negative electrode potential measurement of a test battery provided in an embodiment of this application under a test environment of -20℃ to 45℃ and 0.1C to 4C.

[0042] Figure 6 The graph shows the measurement results of the lithium nucleation negative electrode potential of the test battery provided in an embodiment of this application under a test environment of -20℃ to 45℃ and 0.1C to 4C.

[0043] Figure 7 This is a graph showing the fitting result of the lithium nucleation negative electrode potential provided in an embodiment of this application;

[0044] Figure 8 This is a structural block diagram of a lithium nucleation negative electrode potential determination device provided in some embodiments of this application;

[0045] Figure 9 This is an internal structural diagram of a computer device provided in some embodiments of this application. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0047] The method for determining the lithium nucleation negative electrode potential provided in this application can be applied to electric devices that use lithium-ion batteries, such as electric vehicles and power tools. Taking electric vehicles as an example, electric vehicles are usually equipped with a battery management system. During the charging process of the lithium-ion battery, the battery management system can determine the lithium nucleation negative electrode potential corresponding to the current charging environment of the lithium-ion battery according to the method for determining the lithium nucleation negative electrode potential of this application. This allows the battery management system to control the charging current based on the lithium nucleation negative electrode potential, so as to ensure the charging efficiency of the lithium-ion battery while ensuring that lithium plating does not occur at the negative electrode of the lithium-ion battery, thereby ensuring the service life and performance of the lithium-ion battery.

[0048] In one embodiment, such as Figure 1 As shown, the method is illustrated using an example of an electric device employing a lithium-ion battery. In this embodiment, the method includes the following steps:

[0049] Step 102: For each test environment, during the discharge process of the test battery, acquire multiple electrode potentials of the working electrode of the test battery.

[0050] In this embodiment, the test environment consists of combinations of different temperatures and discharge rates. Since the electrochemical performance of lithium-ion batteries varies under different temperatures and discharge rates, and the lithium nucleation process is also affected, it is necessary to test lithium-ion batteries under multiple different temperature and discharge rate conditions to comprehensively understand the relationship between the lithium nucleation negative electrode potential and environmental factors.

[0051] The test battery is constructed using the negative electrode of the target lithium-ion battery and a lithium metal sheet. Specifically, the test battery is a three-electrode half-cell constructed by using the negative electrode of the target lithium-ion battery as the working electrode, the lithium metal sheet as the counter electrode, and inserting a reference electrode. The lithium metal sheet, as the counter electrode, simulates the insertion and extraction process of lithium ions in the battery, making the test environment closer to the actual operation of a lithium-ion battery. The reference electrode accurately measures the electrode potential of the working electrode. The test battery can be in the form of a coin cell or a pouch cell. The ratio of the charging current of the target lithium-ion battery to the discharging current of the test battery is equal to the ratio of the capacity of the target lithium-ion battery to the capacity of the test battery.

[0052] During battery discharge testing, the electrode potential of the working electrode (i.e., the negative electrode of the target lithium-ion battery) is continuously recorded using a reference electrode. As discharge progresses, a series of electrode potential values ​​corresponding to different test environments are obtained; these values ​​constitute multiple electrode potentials.

[0053] Optionally, when constructing a test battery, the negative electrode can be obtained first. If the target lithium-ion battery is in an unassembled electrode state or an unfilled dry cell state, the battery negative electrode can be obtained directly. If the battery is in a state after being filled with electrolyte, the battery needs to be disassembled, the positive and negative electrodes and the separator separated, and the negative electrode needs to be soaked, cleaned and dried to obtain a clean graphite negative electrode. Then, the negative electrode is used as the working electrode and the lithium metal sheet is used as the counter electrode. A reference electrode is inserted to construct a three-electrode half-cell (test battery). If the negative electrode is not formed, the three-electrode half-cell needs to be formed to ensure that a stable SEI film (Solid Electrolyte Interface) is formed on the surface of the negative electrode. Then, the three-electrode half-cell is discharged at a given battery temperature and a given discharge rate (the working electrode is the positive electrode and the lithium metal counter electrode is the negative electrode to ensure that lithium intercalation occurs in the graphite working electrode). The electrode potential of the working electrode is continuously recorded using the reference electrode.

[0054] Step 104: Determine the minimum value among the multiple electrode potentials corresponding to each test environment as the target electrode potential.

[0055] Understandably, during the lithium plating nucleation process, when the electrode potential reaches its minimum value, it indicates that the lithium ion concentration on the negative electrode surface has reached a critical state, and lithium plating nucleation begins. After continuing to discharge beyond this minimum value, the electrode potential will rise, indicating that lithium plating has already begun. Therefore, this minimum value can be taken as the lithium plating nucleation negative electrode potential (i.e., the target electrode potential) under this test environment.

[0056] Optionally, multiple electrode potentials recorded under each test environment can be compared to determine the minimum value.

[0057] Step 106: Use the target electrode potential under each test environment to fit the equation parameters and obtain the correspondence between the lithium nucleation negative electrode potential and the charging current under each test environment.

[0058] Understandably, by fitting the target electrode potential under each test environment using equation parameters, the correspondence between the lithium nucleation negative electrode potential and the charging current under different charging environments can be obtained. For example, at a specific temperature and discharge rate, based on the fitted equation—that is, the correspondence between the lithium nucleation negative electrode potential and the charging current—the lithium nucleation negative electrode potential corresponding to different charging currents can be calculated. This correspondence can be applied to battery management systems, helping them to determine in real time whether the battery is approaching the critical state of lithium nucleation based on the current charging current and battery temperature, thereby optimizing the charging strategy, preventing lithium nucleation, and improving battery safety and lifespan.

[0059] Optionally, based on the mechanism equation describing the lithium plating nucleation process, the target electrode potential under each test environment can be substituted into the mechanism equation, and mathematical software (such as Matlab) can be used to fit the parameters and solve for the parameters in the equation.

[0060] The aforementioned method for determining the lithium nucleation negative electrode potential avoids the problems of large errors and low time resolution in traditional methods that use graphite to determine the starting point of lithium nucleation by recording the electrode potential of the working electrode and taking the minimum value as the lithium nucleation negative electrode potential. It also avoids the problem of misjudgment that occurs when traditional methods use the voltage value after the rebound of the step current in a lithium button cell to determine the starting point of lithium nucleation. Furthermore, the method in this application, through equation parameter fitting, obtains the correspondence between the lithium nucleation negative electrode potential and the charging current. This helps the target lithium-ion battery determine the corresponding lithium nucleation negative electrode potential in real time according to the charging environment during the charging process of the device. This allows the battery management system to control the charging current of the target lithium-ion battery based on the current lithium nucleation negative electrode potential, thus ensuring both charging efficiency and preventing lithium deposition at the negative electrode, thereby guaranteeing the battery's lifespan and performance.

[0061] In one embodiment, the target electrode potential under each test environment is used to fit the equation parameters to obtain the correspondence between the lithium nucleation negative electrode potential and the charging current under each test environment, including:

[0062] For each test environment, the equation parameters are fitted using the target electrode potential and the mechanism equation of the lithium plating nucleation process to obtain the corresponding relationship between the lithium plating nucleation negative electrode potential and the charging current under each test environment.

[0063] The mechanistic equation is a mathematical equation based on electrochemical theory and the physicochemical process of lithium nucleation. It describes the intrinsic relationship between the lithium nucleation negative electrode potential and the charging current. The mechanistic equation can provide a quantitative description of the lithium nucleation process at the theoretical level, thereby revealing the intrinsic connection between the lithium nucleation negative electrode potential and the charging current.

[0064] Understandably, in a battery management system, based on the relationship between the lithium nucleation negative electrode potential and the charging current obtained from the mechanistic equation, the charging strategy of the target lithium-ion battery can be adjusted in real time according to the current charging current and ambient temperature. This avoids the target lithium-ion battery from operating in the critical state of lithium plating, thereby improving the battery's safety and lifespan.

[0065] In this embodiment, parameter fitting using the mechanistic equation can more accurately describe the relationship between the lithium nucleation negative electrode potential and the charging current. Furthermore, by fitting parameters for each test environment, the obtained correspondence can adapt to different operating conditions and has better generalization, meaning it can be applied to various practical lithium-ion battery usage scenarios, providing reliable guidance for lithium-ion battery management under different charging environments.

[0066] In one embodiment, the mechanistic equation for the lithium plating nucleation process includes: ,in, To test the battery's discharge current; This is the negative electrode potential for lithium nucleation. These are the first fitted parameters; is the second fitting parameter.

[0067] Specifically, , It is the height of lithium dendrites that can stably nucleate (equal to the diameter of a single lithium atom); It is the interfacial tension between the crystal nucleus and the solution; It is the density of lithium metal; It represents the number of electrons transferred during the lithium plating reaction; It is Faraday's constant; It is the relative atomic mass of lithium; It is the gas constant; It is Avogadro's constant; It's the battery temperature. All other things being equal, Changes in the value of will alter the critical conditions for lithium nucleation; for example, when An increase in the absolute value of indicates that the energy barrier required to overcome for lithium nucleation may increase, necessitating a higher overpotential (i.e., a larger overpotential). (or a larger current) Only then can lithium nucleation occur.

[0068] , It is a precondition for fitting; and Interfacial tensions between the crystal nucleus and the electrode, and between the electrode and the solution, respectively; It is the molar mass of lithium. It can be regarded as a constant term related to the intrinsic characteristics of the lithium nucleation process, reflecting the influence of factors other than the lithium nucleation overpotential and current on the lithium nucleation process. These factors may include the microstructure of the electrode surface, the ion conduction characteristics of the solution, etc. The magnitude of the value affects the intercept of the entire equation, thus influencing the linear relationship between the lithium nucleation negative electrode potential and the discharge current. Under different test environments, The changes in the value reflect the combined influence of environmental factors on the lithium nucleation process. For example, different temperatures may lead to changes in the nucleation process. The value changes, which in turn affects the critical current and potential for lithium nucleation.

[0069] The mechanism equation for the lithium nucleation process is applicable to applications with limited data, relatively simple lithium deposition processes, and high computational efficiency requirements.

[0070] Optionally, a genetic algorithm can be used to optimize the parameters to determine the first and second fitting parameters. Specifically, this can be done by first encoding the parameters to be optimized. and Encode the data as chromosomes (usually binary strings), with each chromosome representing a set of possible parameter combinations; then initialize the population: randomly generate a set of chromosomes as the initial population, with each chromosome corresponding to a set of chromosomes. and The value; then perform fitness evaluation: according to the equation The process involves calculating the fitting error (e.g., mean squared error) for each chromosome and using the reciprocal of the error as the fitness value. A higher fitness value indicates a better combination of parameters for that chromosome. Next, a selection operation is performed: based on the fitness value, a subset of chromosomes are selected as parents to generate the next generation. Selection methods can include roulette wheel selection, tournament selection, etc. Then, a crossover operation is performed: the selected parent chromosomes are crossovered, exchanging some of their genes to generate new offspring chromosomes. Next, a mutation operation is performed: the newly generated offspring chromosomes are mutated, randomly changing some gene values. Mutation increases population diversity and prevents the algorithm from getting stuck in local optima. Finally, the population is updated: some or all of the parent chromosomes are replaced with the newly generated offspring chromosomes to form a new population. This process of fitness evaluation and population update is repeated until a preset termination condition is met, such as reaching the maximum number of iterations or the fitness value converging to a certain level. The optimal chromosome is then obtained. and The value of is the result of the optimization.

[0071] The mechanism equation of the lithium nucleation process in this embodiment is simple, which helps to reduce the complexity of analyzing the relationship between the lithium nucleation negative electrode potential and the discharge current, thereby making the amount of computation required for parameter fitting and calculation relatively small.

[0072] In one embodiment, the mechanistic equation for the lithium plating nucleation process includes: ,in, To test the battery's discharge current; This is the negative electrode potential for lithium nucleation. These are the first fitted parameters; is the second fitting parameter.

[0073] It is understandable that the mechanism equation for this lithium plating nucleation process is a Taylor expansion, which can be optimized using the least squares method. Specifically, the mechanism equation for the lithium plating nucleation process can be fitted using the least squares method. During the fitting process, the optimal parameter values ​​are determined by minimizing the sum of squared errors between the observed values ​​and the model's predicted values. That is, the error function value needs to be gradually reduced until it converges to less than a preset error threshold, thereby determining the final first and second fitting parameters. This mechanism equation for the lithium plating nucleation process is suitable for applications with abundant data, complex lithium plating processes, and high requirements for fitting accuracy.

[0074] The mechanism equation for the lithium nucleation process in this embodiment can more accurately describe the relationship between the discharge current and the negative electrode potential of lithium nucleation during the lithium nucleation process compared to a simple linear model.

[0075] In one embodiment, such as Figure 2 As shown, the method also includes:

[0076] Step 202: Obtain the historical discharge rate and historical discharge temperature of the sample lithium-ion battery during the historical charging process.

[0077] Among them, the sample lithium-ion battery and the target lithium-ion battery are of the same type, that is, the negative electrode of the sample lithium-ion battery and the negative electrode of the target lithium-ion battery are the same. For example, the materials and specifications need to be strictly consistent. In this way, it can be ensured that the historical data obtained is of reference value for the target lithium-ion battery, because batteries of the same type may have similar performance under the same working conditions.

[0078] Optionally, the historical discharge rate and historical discharge temperature of the sample lithium-ion battery can be obtained from the battery management system.

[0079] Step 204: Divide the grid according to the historical discharge rate and historical discharge temperature to construct each test environment.

[0080] Mesh generation is a method of discretizing a continuous variable space. By dividing the two-dimensional space formed by the two variables of historical discharge rate and historical discharge temperature, small mesh cells can be obtained, each representing a specific test environment.

[0081] Optionally, the range of values ​​for the historical discharge rate and historical discharge temperature can be determined first based on the acquired historical discharge rate and historical discharge temperature data. For example, the range of historical discharge rate might be 0.1C to 5C, and the range of historical discharge temperature might be -20℃ to 60℃. Then, the grid spacing for discharge rate and discharge temperature can be set according to actual needs and data characteristics. For example, the grid spacing for discharge rate can be set to 0.1C, and the grid spacing for discharge temperature can be set to 5℃. Then, according to the set grid spacing, the range of values ​​for discharge rate and discharge temperature can be divided into small grid units. Each grid unit is determined by a range of values ​​for discharge rate and discharge temperature. For example, a grid unit might correspond to a test environment with a discharge rate of 1.0C to 1.1C and a discharge temperature of 20℃ to 25℃.

[0082] In this embodiment, the test environment constructed by dividing the sample lithium-ion battery into grids based on its historical discharge rate and historical discharge temperature can more realistically simulate the actual use environment of the target lithium-ion battery. This ensures the accuracy and reliability of the correspondence between the lithium nucleation negative electrode potential and the charging current, and further ensures that the subsequent battery management system can accurately and reliably determine the corresponding lithium nucleation negative electrode potential in real time based on the charging environment of the target lithium-ion battery, thereby achieving precise control of the charging process of the target lithium-ion battery.

[0083] In one embodiment, such as Figure 3 As shown, the method also includes:

[0084] Step 302: Determine the charging environment of the target lithium-ion battery.

[0085] The charging environment can refer to various external conditions and parameters involved in the charging process of the target lithium-ion battery, which may include battery temperature and charging current.

[0086] Optionally, a temperature sensor can be used to measure the temperature of the target lithium-ion battery in real time. The temperature sensor can be installed on the surface or inside the battery to accurately obtain the temperature data of the target lithium-ion battery. The charging current can be measured using a current sensor, which is typically connected in series in the charging circuit and can monitor the charging current value in real time.

[0087] Step 304: Based on the charging environment, determine the target correspondence with the charging environment from the correspondence between the lithium nucleation negative electrode potential and the charging current under each test environment.

[0088] The target correspondence refers to the relationship between the lithium nucleation negative electrode potential and the charging current under a test environment that matches the current charging environment of the target lithium-ion battery.

[0089] Optionally, the charging environment (such as battery temperature and charging current) determined in step 302 can be compared with each test environment constructed in step 204. For example, the similarity between the parameters of the charging environment and the parameters of each test environment can be calculated, and the correspondence between the lithium nucleation negative electrode potential and the charging current corresponding to the test environment with the highest similarity can be selected as the target correspondence. If the parameters of the charging environment happen to fall between two test environments, an interpolation method can be used to determine the target correspondence. For example, linear interpolation or a more complex interpolation algorithm can be used to estimate the target correspondence under the current charging environment based on the correspondence between two adjacent test environments.

[0090] Step 306: Charge the target lithium-ion battery using the target correspondence relationship.

[0091] Optionally, the charging current can be adjusted based on a target correlation. For example, if the target correlation indicates that under the current charging environment, when the lithium nucleation negative electrode potential reaches a certain threshold, the charging current needs to be reduced to prevent lithium plating, the charging device will adjust the charging current in real time according to this correlation to prevent the negative electrode potential from dropping below the lithium nucleation negative electrode potential. Furthermore, during the charging process, the actual values ​​of the lithium nucleation negative electrode potential and the charging current can be continuously monitored and compared with the target correlation. If the actual value of the charging current deviates from the target correlation, the charging strategy will be adjusted promptly to ensure that the charging process of the target lithium ions always proceeds within a safe and efficient range.

[0092] In this embodiment, by determining the target correspondence and adjusting the charging strategy of the target lithium-ion battery according to the target correspondence, the occurrence of lithium plating can be effectively avoided in different charging environments, thereby reducing the risk of safety accidents such as short circuits and overheating of the target lithium-ion battery. In addition, charging using the target correspondence can enable the battery to be charged with a more appropriate charging current in various charging environments, reducing damage to the internal structure of the battery and thus extending the battery's service life.

[0093] In a detailed embodiment, taking a 1.75Ah soft-pack lithium-ion battery as an example, with nickel-cobalt-manganese material as the positive electrode and artificial graphite as the negative electrode, and the battery being an unfilled dry cell, the process of testing the battery in this application to obtain the correspondence between the lithium nucleation negative electrode potential and the charging current under each test environment is as follows:

[0094] The first step is to disassemble the battery and remove the negative electrode of the target lithium-ion battery;

[0095] The second step involves punching the negative electrode of the target lithium-ion battery into a 12mm diameter disc to serve as the working electrode; using a 16mm diameter lithium metal sheet as the counter electrode; punching the separator (provided by the battery manufacturer) into a 19mm diameter disc; and using the electrolyte (provided by the battery manufacturer), fabricating these materials into a coin cell (test cell). Simultaneously, during the coin cell fabrication process, a copper wire is inserted into the center of the coin cell as a reference electrode.

[0096] Using a graphite electrode as the positive electrode and a lithium metal sheet as the negative electrode, a three-electrode coin cell is formed by discharging and charging once at a 0.1C rate.

[0097] Using a lithium metal sheet as the positive electrode and a copper wire as the negative electrode, the copper wire lithium-plated reference electrode was activated by charging with a current of 50 microamps for 2 hours.

[0098] The third step involves using a graphite electrode as the positive electrode and a lithium metal sheet as the negative electrode to discharge the three-electrode coin cell at 0°C and 1C rate, while continuously recording the electrode potential of the graphite electrode using a reference electrode.

[0099] The fourth step is to continue discharging until the electrode potential reaches its minimum value, and then continue discharging for 1 hour after reaching the minimum value, followed by resting for 3 hours; the entire measurement curve is as follows. Figure 4 As shown;

[0100] The fifth step is to use the minimum value as the lithium nucleation potential of the graphite anode of this battery at 0°C and 1C rate.

[0101] Step 6: The required temperature range for testing is -20℃ to 45℃, and the magnification range is 0.1℃ to 4℃. This range is divided into grids. For each temperature and magnification point on the grid, steps 3-5 are repeated. The test curve is shown below. Figure 5 As shown; the lithium nucleation potentials of the negative electrode within the required temperature and rate ranges for testing were obtained, and the results are as follows. Figure 6 As shown.

[0102] Step 7: Based on the derived mechanism equation for the lithium plating nucleation boundary. Based on the test results in step six, the parameters in the equation are determined ( and Optimization and fitting. Specifically, a genetic algorithm can be used to optimize the parameters; after optimization, the fitting result is as follows: Figure 7 As shown by the solid line in the image.

[0103] In another embodiment, the Taylor expansion of the mechanistic equation can be used, and the least squares method can be used for optimal fitting. The corresponding mechanistic equation is: .

[0104] Based on this method, the lithium nucleation negative electrode potential and its mathematical expression can be obtained for lithium-ion batteries at various battery temperatures and rates, which can guide the precise control of the fast charging process of lithium-ion batteries.

[0105] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0106] Based on the same inventive concept, this application also provides a lithium nucleation negative electrode potential determination device for implementing the lithium nucleation negative electrode potential determination method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations of one or more embodiments of the lithium nucleation negative electrode potential determination device provided below can be found in the limitations of the lithium nucleation negative electrode potential determination method described above, and will not be repeated here.

[0107] In one embodiment, such as Figure 8 As shown, a device for determining the nucleation potential of lithium plating anode is provided, comprising: a potential data acquisition module 802, a target potential determination module 804, and a correspondence determination module 806, wherein:

[0108] The potential data acquisition module 802 is used to acquire multiple electrode potentials of the working electrode of the test battery during the discharge process of the test battery for each test environment; the test battery is constructed using the negative electrode of the target lithium-ion battery and a lithium metal sheet; the working electrode is the electrode corresponding to the negative electrode of the target lithium-ion battery; the ratio of the charging current of the target lithium-ion battery to the discharging current of the test battery is equal to the ratio of the capacity of the target lithium-ion battery to the capacity of the test battery.

[0109] The target potential determination module 804 is used to determine the minimum value among multiple electrode potentials corresponding to each test environment as the target electrode potential.

[0110] The correspondence determination module 806 is used to fit the equation parameters using the target electrode potential under each test environment to obtain the correspondence between the lithium nucleation negative electrode potential and the charging current under each test environment.

[0111] In one embodiment, the correspondence determination module 806 is further configured to: for each test environment, use the target electrode potential and the mechanism equation of the lithium plating nucleation process to perform equation parameter fitting to obtain the correspondence between the lithium plating nucleation negative electrode potential and the charging current under each test environment.

[0112] In one embodiment, the correspondence determination module 806 is further used to determine the mechanism equation for the lithium plating nucleation process, including: ,in, To test the battery's discharge current; This is the negative electrode potential for lithium nucleation. These are the first fitted parameters; is the second fitting parameter.

[0113] In one embodiment, the correspondence determination module 806 is further used to determine the mechanism equation for the lithium plating nucleation process, including: ,in, To test the battery's discharge current; This is the negative electrode potential for lithium nucleation. These are the first fitted parameters; is the second fitting parameter.

[0114] In one embodiment, the device is further configured to: acquire the historical discharge rate and historical discharge temperature of the sample lithium-ion battery during historical charging; the sample lithium-ion battery is of the same type as the target lithium-ion battery; and construct each test environment by dividing the grid according to the historical discharge rate and historical discharge temperature.

[0115] In one embodiment, the apparatus is further configured to: determine the charging environment of the target lithium-ion battery; based on the charging environment, determine a target correspondence with the charging environment from the correspondence between the lithium nucleation negative electrode potential and the charging current under each test environment; and charge the target lithium-ion battery using the target correspondence.

[0116] Each module in the aforementioned lithium plating nucleation negative electrode potential determination device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0117] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 9As shown, the computer device includes a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements a method for determining the negative electrode potential of lithium plating nucleation. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device casing, or an external keyboard, touchpad, or mouse.

[0118] Those skilled in the art will understand that Figure 9 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0119] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0120] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0121] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0122] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0123] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0124] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0125] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method of determining a lithium precipitation nucleation negative electrode potential, characterized by, The method comprises: For each test environment, a plurality of electrode potentials of a working electrode of a test battery are obtained during a discharge process of the test battery; the test battery is constructed by using a negative electrode of a target lithium ion battery and a metal lithium sheet; the working electrode is an electrode corresponding to the negative electrode of the target lithium ion battery; a ratio of a charging current of the target lithium ion battery to a discharge current of the test battery is equal to a ratio of a capacity of the target lithium ion battery to a capacity of the test battery; A minimum value of the plurality of electrode potentials corresponding to each test environment is determined as a target electrode potential; An equation parameter fitting is performed by using the target electrode potential under each test environment, to obtain a corresponding relationship between a lithium precipitation nucleation negative electrode potential and a charging current under each test environment.

2. The method of claim 1, wherein, The equation parameter fitting by using the target electrode potential under each test environment to obtain the corresponding relationship between the lithium precipitation nucleation negative electrode potential and the charging current under each test environment comprises: For each test environment, an equation parameter fitting is performed by using the target electrode potential and a mechanism equation of a lithium precipitation nucleation process, to obtain the corresponding relationship between the lithium precipitation nucleation negative electrode potential and the charging current under each test environment.

3. The method of claim 2, wherein, The mechanism equation for the lithium extraction nucleation process includes: wherein, is the discharge current for the test battery; is the lithium extraction nucleation negative potential; is a first fitting parameter; is a second fitting parameter.

4. The method of claim 2, wherein, The mechanism equation for the lithium extraction nucleation process includes: wherein, is the discharge current for the test battery; is the lithium extraction nucleation negative potential; is a first fitting parameter; is a second fitting parameter.

5. The method according to any one of claims 1 to 4, characterized in that, The method further comprises: A historical discharge rate and a historical discharge temperature of a sample lithium ion battery in a historical charging process are obtained; the sample lithium ion battery is of the same type as the target lithium ion battery; A grid division is performed according to the historical discharge rate and the historical discharge temperature, to construct each test environment.

6. The method of claim 1, wherein, The method further comprises: A charging environment of the target lithium ion battery is determined; Based on the charging environment, a target corresponding relationship corresponding to the charging environment is determined from the corresponding relationship between the lithium precipitation nucleation negative electrode potential and the charging current under each test environment; The target lithium ion battery is charged by using the target corresponding relationship.

7. A lithium extraction nucleation anode potential determination device, characterized by, The device comprises: A potential data obtaining module is configured to obtain, for each test environment, a plurality of electrode potentials of a working electrode of a test battery during a discharge process of the test battery; the test battery is constructed by using a negative electrode of a target lithium ion battery and a metal lithium sheet; the working electrode is an electrode corresponding to the negative electrode of the target lithium ion battery; a ratio of a charging current of the target lithium ion battery to a discharge current of the test battery is equal to a ratio of a capacity of the target lithium ion battery to a capacity of the test battery; A target potential determining module is configured to determine a minimum value of the plurality of electrode potentials corresponding to each test environment as a target electrode potential; A corresponding relationship determining module is configured to perform an equation parameter fitting by using the target electrode potential under each test environment, to obtain a corresponding relationship between a lithium precipitation nucleation negative electrode potential and a charging current under each test environment.

8. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that, The processor implements the steps of the method of any one of claims 1 to 6 when executing the computer program.

9. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program, when executed by the processor, implements the steps of the method of any one of claims 1 to 6.

10. A computer program product comprising a computer program, characterized in that, The computer program, which when executed by the processor, implements the steps of the method of any one of claims 1 to 6.

Images