Battery cell capacity grading method and device and computer readable storage medium

Abstract

The invention discloses a capacity grading method and a capacity grading device for battery cell capacity, and a computer readable storage medium. The method comprises the following steps: determining a target capacity grading environment temperature interval; under the condition that the environment temperature is in the target capacity grading environment temperature interval, the conversion rate between the capacity grading capacity and the calibrated capacity grading capacity is determined; and correcting the actual capacity grading capacity based on the conversion rate to obtain a corrected capacity grading capacity, and carrying out capacity grading on the battery cell according to the corrected capacity grading capacity. According to the capacity grading method, the influence of temperature fluctuation can be eliminated, the problem that the current capacity grading capacity test of the battery cells is inaccurate is solved, and the battery cells can be accurately grouped, so that the service life of the battery module is prolonged.

Description

Technical Field

[0001] The present application relates to the field of battery cell technology, and in particular to a battery cell capacity division method, a computer-readable storage medium, and a battery cell capacity division device. Background Art

[0002] Lithium-ion batteries are widely used in the digital and power energy industries due to their high energy density, long cycle life and no memory effect. When lithium-ion batteries leave the factory, they need to be grouped to ensure that the battery capacity, internal resistance, self-discharge, voltage, etc. in each group are close to the same, so that the service life of the battery module can be effectively increased during use. This requires that each item must be screened and the data must be close to accurate.

[0003] At present, the relevant technology relies on the capacity division worker to determine the capacity of the battery cell. Usually, the battery cell is fully charged at constant current and constant voltage in the capacity division cabinet, and then discharged at a certain rate and constant current according to the process or customer requirements after standing for a period of time. However, since the capacity division process often releases heat, the temperature difference at each position of the capacity division room is large, and the temperature of the capacity division environment fluctuates significantly at different times of the year. Since the capacity of the battery cell varies greatly with the discharge temperature, the battery cell capacity test is ultimately inaccurate, the assembly is "failed", and the quality problem is affected. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the first purpose of the present application is to propose a method for cell capacity division, determine a target cell capacity division ambient temperature range, determine the conversion rate between the cell capacity division capacity and the calibrated cell capacity division capacity when the ambient temperature is in the target cell capacity division ambient temperature range, correct the actual cell capacity division capacity based on the conversion rate, obtain the corrected cell capacity division capacity, and classify the cell capacity according to the corrected cell capacity division capacity, thereby eliminating the influence of temperature fluctuations, solving the problem of inaccurate cell capacity division capacity test, and enabling accurate cell grouping to improve the service life of the battery module.

[0005] A second object of the present application is to provide a computer-readable storage medium.

[0006] The third objective of the present application is to provide a capacity division device for battery cells.

[0007] To achieve the above-mentioned purpose, the first aspect of the present application proposes a method for capacity division of battery cells, the method comprising: determining a target capacity division ambient temperature range; when the ambient temperature is within the target capacity division ambient temperature range, determining a conversion rate between the capacity division capacity and a calibrated capacity division capacity; based on the conversion rate, correcting the actual capacity division capacity to obtain a corrected capacity division capacity, so as to classify the capacity of the battery cells according to the corrected capacity division capacity.

[0008] According to the cell capacity division method of the embodiment of the present application, the target cell capacity division ambient temperature range is determined, and when the ambient temperature is within the target cell capacity division ambient temperature range, the conversion rate between the cell capacity division capacity and the calibrated cell capacity division capacity is determined, and the actual cell capacity division capacity is corrected based on the conversion rate to obtain the corrected cell capacity division capacity, so as to classify the cell capacity according to the corrected cell capacity division capacity. Thus, the method can eliminate the influence of temperature fluctuations, solve the problem of inaccurate cell capacity division capacity testing, and accurately group the cells to increase the service life of the battery module.

[0009] In addition, the cell capacity division method according to the above embodiment of the present application may also have the following additional technical features:

[0010] According to one embodiment of the present application, determining the target capacity differentiation ambient temperature range includes: controlling the battery cell to discharge according to a preset discharge current at different temperatures to determine the capacity retention rate at different temperatures; determining a capacity retention rate curve based on multiple temperatures and the capacity retention rate corresponding to each of the temperatures; and determining the target capacity differentiation ambient temperature range based on the capacity retention rate curve.

[0011] According to one embodiment of the present application, determining the target capacity separation ambient temperature range based on the capacity retention rate curve includes: determining a capacity retention rate fitting equation based on the capacity retention rate curve; determining a target temperature based on the capacity retention rate fitting equation, wherein the target temperature is the temperature corresponding to when the capacity retention rate is maximum; and determining a temperature range greater than or equal to the target temperature as the target capacity separation ambient temperature range.

[0012] According to one embodiment of the present application, determining the target temperature based on the capacity retention rate fitting equation includes: taking the temperature corresponding to zero after derivation of the capacity retention rate fitting equation as the target temperature.

[0013] According to one embodiment of the present application, determining the conversion rate between the divided capacity and the calibrated divided capacity includes: determining an average divided capacity of a preset number of battery cells, and determining an average calibrated capacity at a calibration temperature; and determining the conversion rate based on the average divided capacity and the average calibrated capacity.

[0014] According to one embodiment of the present application, determining the conversion rate based on the average divided capacity and the average rated capacity includes: determining the conversion rate based on a ratio of the average rated capacity to the average divided capacity.

[0015] According to an embodiment of the present application, the correcting the actual sub-capacity based on the conversion rate to obtain the corrected sub-capacity includes: obtaining the corrected sub-capacity based on the product of the actual sub-capacity and the conversion rate.

[0016] According to one embodiment of the present application, the capacity grading of the battery cells according to the corrected divided capacity includes: when the corrected divided capacity is greater than or equal to the rated capacity, grading the battery cells according to the capacity interval in which the corrected divided capacity is located; when the corrected divided capacity is less than or equal to the rated capacity, downgrading the battery cells.

[0017] In order to achieve the above-mentioned purpose, the second embodiment of the present application proposes a computer-readable storage medium, on which a program is stored, and when the program is executed by a processor, the above-mentioned method for dividing the capacity of a battery cell is implemented.

[0018] According to the computer-readable storage medium of the embodiment of the present application, by implementing the above-mentioned method of cell capacity division during execution, the influence of temperature fluctuations can be eliminated, the problem of inaccurate cell capacity division testing can be solved, and the battery cells can be accurately grouped to increase the service life of the battery module.

[0019] To achieve the above-mentioned purpose, the third aspect of the present application proposes a capacity division device for a battery cell, the device comprising: a first determination module, used to determine a target capacity division ambient temperature range; a second determination module, used to determine the conversion rate between the capacity division capacity and the calibrated capacity division capacity when the ambient temperature is within the target capacity division ambient temperature range; a grading module, used to correct the actual capacity division capacity based on the conversion rate to obtain a corrected capacity division capacity, so as to grade the capacity of the battery cell according to the corrected capacity division capacity.

[0020] According to the cell capacity division device of the embodiment of the present application, the first determination module is used to determine the target cell capacity division ambient temperature range, the second determination module is used to determine the conversion rate between the cell capacity and the calibrated cell capacity when the ambient temperature is in the target cell capacity division ambient temperature range, and the grading module is used to correct the actual cell capacity division based on the conversion rate to obtain the corrected cell capacity division, so as to grade the cell capacity according to the corrected cell capacity division. Thus, the device can eliminate the influence of temperature fluctuations, solve the problem of inaccurate cell capacity division test, and accurately group the cells to increase the service life of the battery module.

[0021] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of a method for dividing the capacity of a battery cell according to an embodiment of the present application;

[0023] Figure 2Schematic diagram of temperature-capacity retention rate curve according to an embodiment of the present application;

[0024] Figure 3 A flowchart of a method for dividing the capacity of a battery cell according to a specific example of the present application;

[0025] Figure 4 Schematic diagram of a block diagram of a cell capacity division device according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0027] The following describes a method for dividing the capacity of a battery cell, a computer-readable storage medium, and a device for dividing the capacity of a battery cell, which are proposed in embodiments of the present application, with reference to the accompanying drawings.

[0028] Figure 1 The present invention is a flowchart of a method for dividing the capacity of a battery cell according to an embodiment of the present application.

[0029] like Figure 1 As shown, the method for dividing the capacity of a battery cell according to an embodiment of the present application may include the following steps:

[0030] S1, determine the target volumetric ambient temperature range;

[0031] S2, when the ambient temperature is within the target capacity division ambient temperature range, determining the conversion rate between the capacity division capacity and the calibrated capacity division capacity;

[0032] S3, correcting the actual divided capacity based on the conversion rate to obtain a corrected divided capacity, so as to classify the capacity of the battery cells according to the corrected divided capacity.

[0033] Specifically, when accurately measuring and grading the capacity of the battery cell, the target capacity grading ambient temperature range is first determined, that is, an optimal ambient temperature range is determined so that the discharge capacity of the battery cell can reach the maximum and the fluctuation is minimal. For example, a temperature range suitable for grading can be selected based on historical data and experience, or the electrochemical activity of the battery cell at different temperatures can be understood by measuring the AC impedance of the battery cell at different temperatures, thereby determining a suitable grading temperature range, or using a thermal analysis instrument (such as a differential scanning calorimeter DSC) to measure the thermal characteristics of the battery cell at different temperatures, thereby determining the optimal grading temperature range, etc.

[0034] After determining the target sub-capacity ambient temperature range, the conversion rate between the sub-capacity and the calibrated sub-capacity can be determined when the ambient temperature is in the target sub-capacity ambient temperature range. In other words, the performance of lithium-ion batteries, especially the discharge capacity, is very sensitive to temperature. At different temperatures, the discharge behavior of the battery will be different. Therefore, in order to obtain accurate battery performance data, it is necessary to test under controlled temperature conditions. That is, testing within the target sub-capacity ambient temperature range can reduce the impact of ambient temperature fluctuations on the battery performance test results, thereby improving the repeatability and reliability of the test results. That is, by determining the conversion rate between the sub-capacity and the calibrated sub-capacity within the target sub-capacity ambient temperature range, the consistency and reliability of the battery in different batches and under different production conditions can be ensured. When determining the conversion rate, the sub-capacity test can be performed at multiple different temperatures, and then these data can be used to calculate the conversion rate between the sub-capacity and the calibrated capacity at different temperatures.

[0035] After determining the conversion rate, the actual capacity can be corrected based on the conversion rate to obtain the corrected capacity, so as to classify the capacity of the battery cell according to the corrected capacity. Among them, the actual capacity is the discharge capacity of the battery directly measured during the capacity division process. The conversion rate is the proportional relationship between the calibrated capacity and the actual capacity measured under specific conditions (such as at a standard temperature of 25°C). The conversion rate can be used to calibrate the actual capacity to eliminate the influence of environmental factors (such as temperature) on battery performance. By multiplying the actual capacity by the conversion rate, the corrected capacity can be obtained. This corrected capacity can better reflect the true performance of the battery under standard conditions. For example, the corrected capacity can be determined based on the product of the conversion rate and the actual capacity. That is, according to the corrected capacity, the batteries are grouped into different capacity grades, and the batteries in each grade have similar capacities, which can ensure that the batteries in the battery pack are more consistent in performance. As a result, the accuracy of the cell capacity division can be effectively improved, and the error caused by temperature fluctuations can be reduced, thereby improving the service life and performance of the battery module.

[0036] According to an embodiment of the present application, determining the target temperature range of the divided capacity environment includes: controlling the battery cell to discharge according to a preset discharge current at different temperatures to determine the capacity retention rate at different temperatures; determining a capacity retention rate curve based on multiple temperatures and the corresponding capacity retention rate at each temperature; and determining the target temperature range of the divided capacity environment based on the capacity retention rate curve. The preset discharge current can be determined according to actual conditions.

[0037] Specifically, when determining the target capacity-dividing ambient temperature range, first control the battery cell to discharge according to the preset discharge current at different temperatures to determine the capacity retention rate at different temperatures. That is, a number of battery cells can be discharged at a series of different temperatures (for example, -20°C to 80°C), and the discharge capacity at each temperature can be recorded. For example, the discharge can be performed at a current of 1C to determine the capacity retention rate at different temperatures. After determining the capacity retention rate at different temperatures, the capacity retention rate curve can be determined according to multiple temperatures and the corresponding capacity retention rate at each temperature, so that the target capacity-dividing ambient temperature range can be determined according to the capacity retention rate curve. For example, analyze the capacity retention rate curve to find the temperature point corresponding to the maximum capacity retention rate, which is usually the temperature with the best battery performance, or visually observe the temperature point corresponding to the peak of the curve through graphical analysis. That is to say, the capacity-dividing temperature in the capacity-dividing workshop is in this capacity-dividing ambient temperature range, and the discharge capacity of the battery basically reaches the limit, with small fluctuations, so it can be used as the control temperature range of the capacity-dividing process.

[0038] Therefore, the accuracy of battery capacity division can be effectively improved, and the consistency and reliability of the battery pack can be ensured. In practical applications, this optimized temperature control method is of great significance for improving battery performance and extending its service life.

[0039] According to one embodiment of the present application, determining a target capacity separation ambient temperature range based on a capacity retention rate curve includes: determining a capacity retention rate fitting equation based on the capacity retention rate curve; determining a target temperature based on the capacity retention rate fitting equation, wherein the target temperature is a temperature corresponding to a maximum capacity retention rate; and determining a temperature range greater than or equal to the target temperature as a target capacity separation ambient temperature range.

[0040] Specifically, when determining the target capacity retention environment temperature range according to the capacity retention rate curve, the software (such as professional data analysis software, such as MATLAB, Origin, etc.) can be used to obtain the capacity retention rate fitting equation according to the capacity retention rate curve. The equation can describe how the capacity retention rate of the battery cell changes with temperature. After determining the capacity retention rate fitting equation, the target temperature can be determined according to the capacity retention rate fitting equation. The target temperature is the temperature corresponding to the maximum capacity retention rate. Therefore, after determining the target temperature, a temperature range can be determined so that the discharge capacity of the battery can achieve a higher capacity retention rate within this range. That is, this range takes the target temperature as seven points, including several temperature points higher than the target temperature. For example, if the target temperature is 37°C, then the target capacity retention environment temperature range can be a temperature range greater than or equal to 37°C. Within this range, the discharge capacity of the battery basically reaches the limit and fluctuates less, so it can be used as a control temperature range for the capacity retention process.

[0041] According to one embodiment of the present application, determining the target temperature based on the capacity retention rate fitting equation includes: taking the temperature corresponding to zero after derivation of the capacity retention rate fitting equation as the target temperature.

[0042] Specifically, when determining the target temperature based on the capacity retention rate fitting equation, the temperature corresponding to the zero value after the capacity retention rate fitting equation is derived can be used as the target temperature. In other words, in order to find the temperature that maximizes the capacity retention rate, it is necessary to differentiate the fitting equation with respect to temperature and set the derivative equal to zero to solve for the temperature value. For example, the capacity retention rate fitting equation is a*temperature 2 +b*temperature+c, where a, b, and c are coefficients of the equation and need to be determined through data fitting. The derived equation is: 2a*temperature+b=0, and the temperature value that can be solved by this equation is =-b / 2a℃, which can determine the target temperature.

[0043] According to one embodiment of the present application, determining the conversion rate between the divided capacity and the calibrated divided capacity includes: determining the average divided capacity of a preset number of cells and determining the average calibrated capacity at a calibrated temperature; and determining the conversion rate based on the average divided capacity and the average calibrated capacity. The preset number may be determined according to actual conditions.

[0044] Specifically, when determining the conversion rate between the fractional capacity and the calibrated fractional capacity, a certain number of battery cells, such as 32, can be selected to perform fractional capacity tests on these battery cells. The fractional capacity test is usually performed by charging and discharging at a specific current to determine the fractional capacity of each battery cell, thereby calculating the average value of the fractional capacity of these battery cells. This average value represents the average performance of the battery cells under fractional capacity conditions. The above-mentioned battery cells are charged and discharged at a calibrated temperature (such as 25°C in a constant temperature box after being fully charged) to determine the calibrated capacity of each battery cell. The calibrated capacity is the capacity measured under standard conditions, which can better reflect the actual capacity of the battery cell. After determining the average fractional capacity and the average calibrated capacity, the conversion rate can be determined based on the average fractional capacity and the average calibrated capacity. For example, the conversion rate can be a proportional relationship between the fractional capacity and the calibrated capacity, which is used to correct the fractional capacity to make it closer to the actual capacity of the battery cell.

[0045] Further, according to an embodiment of the present application, determining the conversion rate based on the average divided capacity and the average rated capacity includes: determining the conversion rate based on the ratio of the average rated capacity to the average divided capacity.

[0046] Specifically, when determining the conversion rate based on the average divided capacity and the average rated capacity, the conversion rate can be determined by the ratio of the average rated capacity to the average divided capacity. Among them, the average divided capacity is the average value of the capacity obtained after a certain number of cells are tested for divided capacity under specific test conditions (such as specific current and voltage). For example, if 32 cells are tested for divided capacity, the capacity of each cell is 100Ah, 102Ah, 101Ah, etc., then the average divided capacity is the arithmetic mean of these capacity values. The average rated capacity is the average value of the capacity obtained after a certain number of cells are discharged under standard conditions (such as 25°C). For example, if these cells are discharged at 25°C, the rated capacity of each cell is 99Ah, 101Ah, 100Ah, etc., then the average rated capacity is the arithmetic mean of these rated capacity values.

[0047] The conversion rate is the proportional relationship between the sub-capacity and the rated capacity, and is obtained by comparing the average rated capacity with the average sub-capacity. The conversion rate is calculated as η = (average rated capacity / average sub-capacity) × 100%. For example, if the average sub-capacity is 103Ah and the average rated capacity is 101.5Ah, the conversion rate η is 101.5 / 103×100%≈98.5%.

[0048] According to an embodiment of the present application, the actual sub-capacity is corrected based on the conversion rate to obtain the corrected sub-capacity, including: obtaining the corrected sub-capacity based on the product of the actual sub-capacity and the conversion rate.

[0049] Specifically, when the actual divided capacity is corrected according to the conversion rate to obtain the corrected divided capacity, the actual divided capacity can be multiplied by the conversion rate to obtain the corrected divided capacity. That is, the actual divided capacity refers to the standard capacity obtained by testing the battery cell during the divided capacity process, which is measured under specific test conditions (such as specific current and voltage). By multiplying the actual divided capacity by the conversion rate to obtain the corrected divided capacity, the capacity measurement error caused by the test conditions (such as temperature fluctuations) can be corrected, that is, the corrected divided capacity can more accurately reflect the actual capacity of the battery cell, and can be used for further quality control and performance evaluation of the battery cell. In the process of battery cell assembly, the corrected divided capacity can help ensure that the battery cells in the battery module have more consistent performance, thereby improving the performance and life of the entire battery system. As a result, the accuracy of the battery cell capacity test can be effectively improved, thereby improving the overall quality and reliability of the battery product.

[0050] According to an embodiment of the present application, the battery cells are capacity-graded according to the corrected divided capacity, including: when the corrected divided capacity is greater than or equal to the rated capacity, the battery cells are graded according to the capacity interval in which the corrected divided capacity is located; when the corrected divided capacity is less than or equal to the rated capacity, the battery cells are downgraded.

[0051] Specifically, when the capacity of the battery cells is graded according to the corrected divided capacity, the size relationship between the corrected divided capacity and the rated capacity is judged. If the corrected divided capacity is greater than or equal to the rated capacity of the battery cell, then the cells can be graded according to the capacity range in which the corrected divided capacity is located. In other words, the battery cells will be classified into different capacity levels. For example, if the rated capacity is 100Ah, then the battery cells with a corrected divided capacity between 100Ah and 105Ah may be classified as Grade A, and the battery cells with a corrected divided capacity between 95Ah and 100Ah may be classified as Grade B, and so on. If the corrected divided capacity is less than the rated capacity of the battery cell, then these battery cells will be downgraded. In other words, these battery cells will no longer be regarded as products that meet the original specifications and may be used in applications with lower performance requirements or treated as defective products.

[0052] For example, the following grading standards can be set: Grade A: Corrected grading capacity ≥ 100% of the rated capacity, Grade B: 95% ≤ Corrected grading capacity < 100% of the rated capacity. Grade C: 90% ≤ Corrected grading capacity < 95%, Degradation: Corrected grading capacity < 90% of the rated capacity. For cells whose corrected grading capacity is less than the rated capacity, it is necessary to determine the usage scenario after degrading based on the specific circumstances, which may include reprocessing, recycling materials, or use in products with lower performance requirements. Therefore, through such a grading process method, it can ensure that the capacity grading of the battery cells is more accurate, thereby improving the overall performance and reliability of the battery module.

[0053] In summary, as a specific example, in the first stage, 10EA battery cells are selected to measure the discharge capacity retention rate at different temperatures. For example, the temperature of the constant temperature box is set to 20 degrees Celsius, and after standing for 6 hours, the battery cell is fully charged at a constant current and constant voltage of 0.33C. After standing for 6 hours, it is discharged to 0.2V at a constant current of 1C or the rate required by the customer, and the discharge capacity is recorded. The above charging and discharging process can be cycled at multiple temperatures, such as 22, 25, 28, 31, 34, 40, and 45 degrees Celsius to obtain the discharge capacity at different temperatures, and the capacity retention rate at different temperatures is calculated with the discharge capacity at 25 degrees Celsius as 100%. According to the capacity retention rate at different temperatures, a temperature-capacity retention rate curve (capacity retention rate curve) is drawn, such as Figure 2 As shown, the capacity increase is not significant when the temperature exceeds 30°C.

[0054] Determine the temperature-capacity retention rate fitting equation: Capacity retention rate = -0.00101 temperature 2 +0.007553 temperature +0.869, so it can be determined that the temperature corresponding to the highest point of the calculated capacity retention rate is 37°C, which means that the capacity division temperature in the capacity division workshop is ≥37°C. Under this condition, the discharge capacity of the battery cell basically reaches the limit with very small fluctuations.

[0055] In the second stage, 32EA capacity cells are selected, and the average capacity of the capacity is calculated. For example, the average capacity is 103Ah. After fully charged, they are discharged at 25°C in a constant temperature box at a current of 1C, and the average rated capacity is calculated. For example, the average rated capacity is 101.5Ah, and the conversion rate of the capacity to the rated capacity can be determined as η = 100% * 101.5 / 103 = 98.5%. In the third stage, the corrected capacity can be determined as = capacity * 98.5%, so that the capacity can be graded according to the corrected capacity. Therefore, according to the temperature-capacity retention rate fitting equation, the optimal temperature boundary of the capacity division is confirmed. At this temperature, the battery cell discharge basically exerts the limit discharge capacity with small fluctuation. The capacity division can characterize the actual capacity of the battery cell and eliminate the influence of temperature fluctuation. Through the 25℃ capacity calibration, the conversion rate η of the capacity division and the calibrated capacity is determined. Through the conversion rate η of the capacity division and the calibrated capacity, the capacity division is corrected to obtain the capacity correction. According to the capacity correction, the capacity is divided into grades, the capacity in each grade is accurate, and the problem of "failure" of matching is eliminated.

[0056] Combine the following Figure 3 To describe the capacity division method of the present application.

[0057] As a specific example, the method for dividing the capacity of a battery cell of the present application may include the following steps:

[0058] S101, controlling the battery cell to discharge according to a preset discharge current at different temperatures to determine the capacity retention rate at different temperatures.

[0059] S102, determining a capacity retention rate curve based on a plurality of temperatures and a corresponding capacity retention rate at each temperature.

[0060] S103, determining a capacity retention rate fitting equation based on the capacity retention rate curve.

[0061] S104, determining a target temperature based on a capacity retention rate fitting equation, wherein the target temperature is a temperature corresponding to a maximum capacity retention rate.

[0062] S105, determining a temperature range greater than or equal to the target temperature as a target volume distribution environment temperature range.

[0063] S106, when the ambient temperature is within the target capacity-dividing ambient temperature range, determining an average capacity-dividing capacity of a preset number of cells, and determining an average calibrated capacity at a calibrated temperature.

[0064] S107, determining the conversion rate based on the ratio of the average calibrated capacity to the average divided capacity.

[0065] S108, obtaining a corrected divided capacity based on the product of the actual divided capacity and the conversion rate.

[0066] S109, determine whether the corrected capacity is greater than or equal to the rated capacity. If yes, execute step S110; if not, execute step S111.

[0067] S110, classifying the battery cells according to the capacity intervals where the corrected capacity is located.

[0068] S111, downgrading the battery cell.

[0069] In summary, according to the cell capacity division method of the embodiment of the present application, the target division ambient temperature range is determined, and when the ambient temperature is in the target division ambient temperature range, the conversion rate between the division capacity and the calibrated division capacity is determined, and the actual division capacity is corrected based on the conversion rate to obtain the corrected division capacity, so as to classify the capacity of the cell according to the corrected division capacity. As a result, the method can eliminate the influence of temperature fluctuations, solve the problem of inaccurate current cell division capacity testing, and enable the cells to be accurately grouped to increase the service life of the battery module.

[0070] Corresponding to the above embodiments, the present application also proposes a computer-readable storage medium.

[0071] The computer-readable storage medium of the embodiment of the present application stores a program thereon, and when the program is executed by a processor, the above-mentioned method for dividing the capacity of a battery cell is implemented.

[0072] According to the computer-readable storage medium of the embodiment of the present application, by executing the above-mentioned battery cell capacity division method, the influence of temperature fluctuations can be eliminated, the problem of inaccurate battery cell capacity division testing can be solved, and the battery cells can be accurately grouped to increase the service life of the battery module.

[0073] Corresponding to the above-mentioned embodiment, the present application also proposes a capacity division device for battery cells.

[0074] like Figure 4 As shown, the cell capacity classification device 100 according to the embodiment of the present application includes: a first determination module 110 , a second determination module 120 and a binning module 130 .

[0075] The first determination module 110 is used to determine the target sub-capacity ambient temperature range. The second determination module 120 is used to determine the conversion rate between the sub-capacity and the calibrated sub-capacity when the ambient temperature is within the target sub-capacity ambient temperature range. The binning module 130 is used to correct the actual sub-capacity based on the conversion rate to obtain the corrected sub-capacity, so as to bin the capacity of the battery cell according to the corrected sub-capacity.

[0076] According to one embodiment of the present application, the first determination module 110 determines a target capacity-dividing ambient temperature range, which is specifically used to: control the battery cell to discharge according to a preset discharge current at different temperatures to determine the capacity retention rate at different temperatures; determine a capacity retention rate curve based on multiple temperatures and the corresponding capacity retention rate at each temperature; determine the target capacity-dividing ambient temperature range based on the capacity retention rate curve.

[0077] According to one embodiment of the present application, the first determination module 110 determines a target capacity separation ambient temperature range based on a capacity retention rate curve, and is specifically used to: determine a capacity retention rate fitting equation based on the capacity retention rate curve; determine a target temperature based on the capacity retention rate fitting equation, wherein the target temperature is the temperature corresponding to the maximum capacity retention rate; and determine a temperature range greater than or equal to the target temperature as a target capacity separation ambient temperature range.

[0078] According to an embodiment of the present application, the first determination module 110 determines the target temperature based on the capacity retention rate fitting equation. Specifically, the temperature corresponding to zero after the derivative of the capacity retention rate fitting equation is taken as the target temperature.

[0079] According to one embodiment of the present application, the second determination module 120 determines the conversion rate between the divided capacity and the calibrated divided capacity, including: determining the average divided capacity of a preset number of battery cells, and determining the average calibrated capacity at the calibration temperature; determining the conversion rate based on the average divided capacity and the average calibrated capacity.

[0080] According to an embodiment of the present application, the second determination module 120 determines the conversion rate based on the average divided capacity and the average calibrated capacity, and is specifically used to determine the conversion rate based on the ratio of the average calibrated capacity to the average divided capacity.

[0081] According to an embodiment of the present application, the grading module 130 corrects the actual grading capacity based on the conversion rate to obtain the corrected grading capacity, specifically for: obtaining the corrected grading capacity based on the product of the actual grading capacity and the conversion rate.

[0082] According to one embodiment of the present application, the grading module 130 grades the capacity of the battery cells according to the corrected graded capacity, specifically for: when the corrected graded capacity is greater than or equal to the rated capacity, grading the battery cells according to the capacity interval in which the corrected graded capacity is located; when the corrected graded capacity is less than or equal to the rated capacity, downgrading the battery cells.

[0083] It should be noted that for details not disclosed in the cell capacity division device of the embodiment of the present application, please refer to the details disclosed in the cell capacity division method of the embodiment of the present application, and the details will not be repeated here.

[0084] According to the cell capacity division device of the embodiment of the present application, the first determination module is used to determine the target cell capacity division ambient temperature range, the second determination module is used to determine the conversion rate between the cell capacity and the calibrated cell capacity when the ambient temperature is in the target cell capacity division ambient temperature range, and the grading module is used to correct the actual cell capacity division based on the conversion rate to obtain the corrected cell capacity division, so as to grade the cell capacity according to the corrected cell capacity division. Thus, the device can eliminate the influence of temperature fluctuations, solve the problem of inaccurate cell capacity division test, and accurately group the cells to increase the service life of the battery module.

[0085] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0086] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0087] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0088] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0089] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0090] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for dividing the capacity of a battery cell, characterized in that: The method comprises: Determine the target volumetric ambient temperature range; When the ambient temperature is within the target volume-dividing ambient temperature range, determining a conversion rate between the volume-dividing capacity and the calibrated volume-dividing capacity; The actual divided capacity is corrected based on the conversion rate to obtain a corrected divided capacity, so as to classify the capacity of the battery cells according to the corrected divided capacity.

2. The method for dividing the capacity of a battery cell according to claim 1, characterized in that: Determining the target volume separation ambient temperature range includes: Controlling the battery cell to discharge according to a preset discharge current at different temperatures to determine the capacity retention rate at different temperatures; determining a capacity retention rate curve based on a plurality of temperatures and the capacity retention rate corresponding to each of the temperatures; The target capacity separation ambient temperature range is determined based on the capacity retention rate curve.

3. The method for dividing the capacity of a battery cell according to claim 2, characterized in that: The determining the target capacity division ambient temperature range based on the capacity retention rate curve includes: Determining a capacity retention rate fitting equation based on the capacity retention rate curve; Determining a target temperature based on the capacity retention rate fitting equation, wherein the target temperature is the temperature corresponding to when the capacity retention rate is maximum; A temperature interval greater than or equal to the target temperature is determined as the target volume distribution environment temperature interval.

4. The method for dividing the capacity of a battery cell according to claim 3, characterized in that: The determining the target temperature based on the capacity retention rate fitting equation comprises: The temperature corresponding to the zero result after derivation of the capacity retention rate fitting equation is taken as the target temperature.

5. The method for dividing the capacity of a battery cell according to claim 1, characterized in that: The determination of the conversion rate between the sub-capacity and the calibrated sub-capacity includes: Determine the average divided capacity of a preset number of cells, and determine the average rated capacity at the rated temperature; The conversion rate is determined based on the average divided capacity and the average rated capacity.

6. The method for dividing the capacity of a battery cell according to claim 5, characterized in that: The determining the conversion rate based on the average divided capacity and the average rated capacity comprises: The conversion rate is determined based on a ratio of the average rated capacity to the average divided capacity.

7. The method for dividing the capacity of a battery cell according to claim 1, characterized in that: The correcting the actual sub-capacity based on the conversion rate to obtain the corrected sub-capacity includes: The corrected sub-capacity is obtained based on the product of the actual sub-capacity and the conversion rate.

8. The method for dividing the capacity of a battery cell according to claim 1, characterized in that: The step of classifying the capacity of the battery cells according to the corrected capacity classification capacity includes: When the corrected capacity is greater than or equal to the rated capacity, the battery cells are graded according to the capacity interval of the corrected capacity; When the corrected divided capacity is less than or equal to the rated capacity, the battery cell is downgraded.

9. A computer-readable storage medium, characterized in that: A program is stored thereon, and when the program is executed by a processor, the method for dividing the capacity of a battery cell according to any one of claims 1 to 8 is implemented.

10. A cell capacity distribution device, characterized in that: The device comprises: A first determination module is used to determine a target volume-dividing ambient temperature range; A second determination module is used to determine the conversion rate between the divided capacity and the calibrated divided capacity when the ambient temperature is within the target divided capacity ambient temperature range; The grading module is used to correct the actual grading capacity based on the conversion rate to obtain a corrected grading capacity, so as to grade the capacity of the battery cell according to the corrected grading capacity.

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