Cell capacity grading method, device and equipment and storage medium

Abstract

The invention provides a battery cell capacity grading method, device and equipment and a storage medium, and at least one round of circulation process including charging and discharging is executed on a battery cell to be subjected to capacity grading; respectively measuring a voltage value and an internal resistance value of the battery cell at at least two different moments of the circulation process; calculating a voltage change rate based on the voltage values at the at least two moments, and calculating an internal resistance change rate based on the internal resistance values at the at least two moments; and screening and / or grouping the battery cells according to the voltage change rate and the internal resistance change rate by adopting the method, so that the screening accuracy of capacity grading of the battery cells and the performance consistency and the service life of a grouped battery pack can be remarkably improved.

Description

Technical Field

[0001] This application relates to the field of battery management, and more specifically, to a cell capacity grading method, apparatus, device, and storage medium. Background Technology

[0002] As the core component of a battery pack, the performance consistency of the battery cell directly determines the overall capacity, cycle life, and safety reliability of the battery pack. To ensure the effectiveness of the battery pack, capacity grading is required during the cell manufacturing process. The core purpose of capacity grading is to test the cell performance parameters through specific charge and discharge processes, and to select cells with consistent performance for grouping based on these parameters. This avoids problems such as rapid capacity decay, uneven charge and discharge, or even safety hazards caused by differences in the performance of individual cells. Currently, cell capacity grading has become an indispensable key process in the manufacturing of power batteries, energy storage batteries, and other fields, and its technical level directly affects the quality stability of the end product.

[0003] In existing technologies, the cell capacity grading screening process typically relies solely on measuring a single voltage parameter after a charge-discharge cycle. Specifically, after completing the charge-discharge and resting process, only the final voltage data of the cells is collected. Cells with voltage values ​​falling within a preset acceptable range are deemed to meet performance standards, and cells with similar voltage values ​​are grouped together, thus completing the cell screening and grouping operation.

[0004] The aforementioned existing technology has significant drawbacks: it uses only a single voltage parameter as the basis for screening and grouping, neglecting the impact of the crucial performance indicator of cell internal resistance. In actual production, the internal resistance of a cell directly affects its charge / discharge rate compatibility, energy loss, and cycle stability. Even cells with similar voltage values ​​may exhibit significant differences in internal resistance. Grouping cells with inconsistent internal resistance together leads to uneven current distribution and abnormal localized heating during battery charging and discharging, resulting in accelerated overall performance degradation and shortened lifespan. This makes it difficult to meet the stringent requirements for high-performance consistency in high-end applications such as new energy vehicles and large-scale energy storage. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a cell capacity assessment method, apparatus, device and storage medium that can significantly improve the screening accuracy of cell capacity assessment and the performance consistency and service life of the battery pack after grouping.

[0006] In a first aspect, embodiments of this application provide a cell capacity rating method, the method comprising: Perform at least one cycle of charging and discharging on the cells to be rated for capacity. At at least two different moments in the cyclic process, the voltage and internal resistance of the battery cell are measured. The rate of change of voltage is calculated based on the voltage values ​​at at least two times, and the rate of change of internal resistance is calculated based on the internal resistance values ​​at at least two times. Based on the voltage change rate and the internal resistance change rate, the battery cells are screened and / or grouped.

[0007] Optionally, the method further includes: Temperature compensation control is performed during the constant current charging and / or constant current discharging phases of the cycle process. The temperature compensation control includes: The temperature measurement value of the battery cell is obtained through a temperature sensor; Calculate the real-time difference between the measured temperature value and the preset reference temperature; Based on the real-time difference, the current value of the constant current charging or constant current discharging is dynamically adjusted according to a preset compensation rule.

[0008] Optionally, the compensation rule is linear compensation, specifically calculated using the following formula: ; in, The adjusted current, The preset base current value, This is the temperature compensation coefficient. The temperature measurement value is... The reference temperature is [value].

[0009] Optionally, calculating the rate of change of voltage based on voltage values ​​at at least two moments includes: Calculate the difference between the voltage values ​​at the at least two time points; The voltage change rate is obtained by dividing the difference by the time interval between the at least two moments.

[0010] Optionally, the calculation of the rate of change of internal resistance based on the internal resistance values ​​at at least two time points includes: Calculate the difference between the internal resistance values ​​at the at least two time points; The internal resistance change rate is obtained by dividing the difference by the time interval between the at least two moments.

[0011] Optionally, the step of screening and / or grouping the cells based on the voltage change rate and the internal resistance change rate includes: Multiplying the voltage change rate by the first weighting coefficient yields the first weighting parameter; Multiply the rate of change of internal resistance by the second weighting coefficient to obtain the second weighting parameter; The first weighted parameter and the second weighted parameter are summed to obtain the comprehensive evaluation value; The battery cells are screened and / or grouped based on the comprehensive evaluation values.

[0012] Optionally, the step of screening and / or grouping battery cells based on the comprehensive evaluation value includes: The comprehensive evaluation value is compared with a preset qualified threshold, and the battery cell whose comprehensive evaluation value meets the qualified threshold is determined to be a qualified battery cell; And / or, Based on multiple preset performance ranges, cells whose comprehensive evaluation values ​​fall into different performance ranges are classified into corresponding different performance level groups.

[0013] Secondly, embodiments of this application provide a cell capacity testing device, the device comprising: The cycle execution module is used to perform at least one cycle process including charging and discharging for the battery cells to be rated. A cell measurement module is used to measure the voltage and internal resistance of the cell at at least two different moments during the cyclic process. The rate of change calculation module is used to calculate the rate of change of voltage based on voltage values ​​at least two times and the rate of change of internal resistance based on internal resistance values ​​at least two times. A cell capacity assessment module is used to screen and / or group cells based on the voltage change rate and the internal resistance change rate.

[0014] Optionally, the device further includes a temperature compensation control module for: Temperature compensation control is performed during the constant current charging and / or constant current discharging phases of the cycle process. The temperature compensation control includes: The temperature measurement value of the battery cell is obtained through a temperature sensor; Calculate the real-time difference between the measured temperature value and the preset reference temperature; Based on the real-time difference, the current value of the constant current charging or constant current discharging is dynamically adjusted according to a preset compensation rule.

[0015] Optionally, the compensation rule is linear compensation, specifically calculated using the following formula: ; in, The adjusted current, The preset base current value, This is the temperature compensation coefficient. The temperature measurement value is... The reference temperature is [value].

[0016] Optionally, calculating the rate of change of voltage based on voltage values ​​at at least two moments includes: Calculate the difference between the voltage values ​​at the at least two time points; The voltage change rate is obtained by dividing the difference by the time interval between the at least two moments.

[0017] Optionally, the calculation of the rate of change of internal resistance based on the internal resistance values ​​at at least two time points includes: Calculate the difference between the internal resistance values ​​at the at least two time points; The internal resistance change rate is obtained by dividing the difference by the time interval between the at least two moments.

[0018] Optionally, the step of screening and / or grouping the cells based on the voltage change rate and the internal resistance change rate includes: Multiplying the voltage change rate by the first weighting coefficient yields the first weighting parameter; Multiply the rate of change of internal resistance by the second weighting coefficient to obtain the second weighting parameter; The first weighted parameter and the second weighted parameter are summed to obtain the comprehensive evaluation value; The battery cells are screened and / or grouped based on the comprehensive evaluation values.

[0019] Optionally, the step of screening and / or grouping battery cells based on the comprehensive evaluation value includes: The comprehensive evaluation value is compared with a preset qualified threshold, and the battery cell whose comprehensive evaluation value meets the qualified threshold is determined to be a qualified battery cell; And / or, Based on multiple preset performance ranges, cells whose comprehensive evaluation values ​​fall into different performance ranges are classified into corresponding different performance level groups.

[0020] Thirdly, embodiments of this application provide a computer device, including: a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the computer device is running, the processor communicates with the memory via the bus. When the machine-readable instructions are executed by the processor, the steps of the cell capacity assessment method described in any of the optional embodiments of the first aspect are performed.

[0021] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the cell capacity assessment method described in any of the optional embodiments of the first aspect.

[0022] The technical solution provided in this application includes, but is not limited to, the following beneficial effects: For cells undergoing capacity testing, at least one cycle of charging and discharging is performed. This step, through a complete charge-discharge cycle, allows the internal chemical reactions of the cell to proceed fully and reach a stable state, effectively eliminating the interference of residual unstable factors from cell production on performance parameters. The cycle process objectively reflects the actual performance level of the cell, providing real and reliable basic data support for subsequent parameter measurements and performance evaluation.

[0023] The voltage and internal resistance of the battery cell are measured at at least two different points in the cyclic process. This step establishes a two-dimensional basic data system by simultaneously acquiring the two core performance parameters, voltage and internal resistance, at key nodes in the cyclic process. Voltage and internal resistance represent battery cell performance from different dimensions, and the combined measurement method compensates for the inadequacy of a single parameter in comprehensively reflecting battery cell performance, providing sufficient data dimensions for subsequent performance analysis.

[0024] Calculating the voltage change rate and internal resistance change rate based on parameters at at least two time points transforms discrete instantaneous parameters into quantitative indicators reflecting performance change trends, enabling dynamic evaluation of cell performance. The standardized calculation methods for voltage change rate and internal resistance change rate eliminate the influence of single measurement errors, more accurately reflecting the stability characteristics of cell performance and providing a quantifiable and comparable core basis for subsequent screening and grouping.

[0025] Cells are screened and / or grouped based on voltage change rate and internal resistance change rate. This step, by comprehensively considering both voltage change rate and internal resistance change rate, ensures that the core performance trends of cells within the same group are consistent. This screening logic can fundamentally avoid battery pack usage problems caused by differences in key performance parameters of cells, significantly improving the overall performance consistency and lifespan of the grouped battery packs.

[0026] The four steps described above are progressive and mutually supportive, forming a complete technical logic chain. By ensuring data authenticity through a cyclical process, enriching data dimensions through dual-parameter acquisition, quantifying performance through rate of change calculation, and ultimately improving grouping accuracy through dual-index screening, this approach comprehensively solves the problem of one-sided cell performance consistency evaluation in traditional capacity assessment methods, providing key technical support for the assembly of high-reliability battery packs.

[0027] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A flowchart of a cell capacity rating method provided in Embodiment 1 of this application is shown; Figure 2 This diagram illustrates the relationship between a battery cell and a settling cabinet according to Embodiment 1 of this application. Figure 3 This paper shows a diagram illustrating the relationship between a battery cell and an OCV / internal resistance tester provided in Embodiment 1 of this application. Figure 4 This document illustrates a test flowchart provided in Embodiment 1 of this application; Figure 5 A flowchart of a temperature compensation control method provided in Embodiment 1 of this application is shown; Figure 6 A flowchart of a cell screening and grouping method provided in Embodiment 1 of this application is shown; Figure 7 This paper shows a schematic diagram of the structure of a cell capacity testing device provided in Embodiment 2 of this application; Figure 8 A schematic diagram of the structure of a computer device provided in Embodiment 3 of this application is shown. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0031] Example 1 To facilitate understanding of this application, the following is combined with... Figure 1 The flowchart illustrating a cell capacity rating method provided in Embodiment 1 of this application will be used to describe Embodiment 1 of this application in detail.

[0032] See Figure 1 As shown, Figure 1 A flowchart of a cell capacity rating method provided in Embodiment 1 of this application is shown, wherein the method includes steps S101 to S104: S101: Perform at least one cycle of charging and discharging for the cells to be rated.

[0033] Specifically, the cycle process begins with constant current charging, and the base current for constant current charging is calculated using a standard industry formula. .in, This is a coefficient (common values ​​include 0.3). Represents the charge / discharge rate of the battery, 1 The definition is the current intensity at which a battery can be fully discharged within one hour.

[0034] Once the cell voltage reaches the set cutoff voltage, the process switches to constant voltage charging and maintains this state. The entire charging process must be completed inside the charging and discharging equipment, which is a non-open space. It contains a cell positioning device, and the cell terminals must be precisely connected to the charging and discharging pins of the equipment. The charging and discharging operations are achieved through the pins.

[0035] After all battery cells have completed charging, they enter a settling process. The cells need to be transferred to a settling cabinet, which must maintain a stable internal temperature to provide sufficient time for the internal chemical reactions, ultimately stabilizing the cells. The settling time is typically set to 24 or 48 hours. See also... Figure 2 As shown, Figure 2 The diagram shows the relationship between a battery cell and a settling cabinet according to Embodiment 1 of this application, wherein the battery cell is inside the settling cabinet and the settling cabinet needs to ensure that the internal temperature remains stable.

[0036] After the settling period, the battery cell is placed back into the charging and discharging equipment for constant current discharge. After the discharge is complete, the battery cell is removed and settling period is repeated. Depending on the actual needs, the entire cycle can be repeated, or a specific step can be performed after a certain process (such as constant current charging after constant current discharge). Such adjustments will not affect the core effectiveness of this solution.

[0037] S102: At at least two different moments during the cycle, measure the voltage and internal resistance of the battery cell.

[0038] Specifically, measurements are typically taken at two key points: after charging and allowing the device to rest completely, and after discharging and allowing the device to rest completely. The measurement operation must be performed using OCV / internal resistance testing equipment. See [link / reference] Figure 3 As shown, Figure 3The diagram illustrates the relationship between a battery cell and an OCV / internal resistance tester according to Embodiment 1 of this application. The tester operates as follows: positive and negative probes are connected to the positive and negative terminals of the battery cell, transmitting the collected electrical signals to the internal processor. The processor analyzes and processes the signals using a preset algorithm, directly outputting the open-circuit voltage (OCV) and internal resistance value of the battery cell at that moment. These measurement data will serve as the core basis for subsequent calculations of the voltage change rate and internal resistance change rate.

[0039] S103: Calculate the rate of change of voltage based on the voltage values ​​at at least two times, and calculate the rate of change of internal resistance based on the internal resistance values ​​at at least two times.

[0040] Specifically, the voltage change rate is calculated using the industry-standard K-value method, with the following formula: .in, This indicates the open-circuit voltage of the battery cell before discharge. This indicates the open-circuit voltage of the battery cell after discharge. This K value represents the time difference between two voltage measurements. It is primarily used to characterize the self-discharge characteristics of the battery cell and is also denoted as K in this scheme. .

[0041] The formula for calculating the rate of change of internal resistance is: .in, This indicates the internal resistance of the battery cell before discharge. This indicates the internal resistance of the battery cell after discharge. The time difference must be consistent with the time difference used to calculate the rate of change of voltage. Used to characterize the rate of change of the cell's internal resistance. The rate of change of voltage and the rate of change of internal resistance together constitute the core evaluation indicators of cell performance consistency.

[0042] S104: Based on the voltage change rate and the internal resistance change rate, the cells are screened and / or grouped.

[0043] Specifically, the filtering and grouping operations require first sorting the voltage change rate ( ) and the rate of change of internal resistance ( Combined with the weighting coefficients, a comprehensive evaluation value is calculated, and then subsequent operations are performed based on this comprehensive evaluation value.

[0044] This process effectively addresses the shortcomings of the traditional K-value method: the traditional K-value method only uses self-discharge rate (K value) as the grouping basis, which may result in cells with different internal resistances being grouped together. However, this solution, by comprehensively considering voltage and internal resistance changes, can more accurately screen cells with consistent performance, avoiding the impact of internal resistance differences on the overall performance and reliability of subsequent battery packs.

[0045] In an alternative implementation, temperature compensation control is performed during the constant current charging and / or constant current discharging phases of the cycle process.

[0046] Specifically, traditional constant current charging and discharging methods do not consider the impact of temperature on the battery cell, assuming that the cell temperature remains constant during charging and discharging. However, in practical applications, even if the capacity testing equipment has temperature control functions, slight differences in material density, electrolyte concentration, etc., between different battery cells will still result in temperature differences, which in turn will lead to changes in the charge and discharge rate, ultimately affecting the consistency of the battery cells.

[0047] See Figure 4 As shown, Figure 4 The diagram illustrates the internal structure of a capacity testing device according to Embodiment 1 of this application. The diagram fully shows the core components of the capacity testing device, including the device body, control unit, charging / discharging device terminals, and battery cell assembly. The battery cell assembly is placed in the non-open space of the capacity testing device and fixed by a cell positioning device. Its terminals are precisely connected to the charging / discharging device terminals to achieve charging and discharging operations. The control unit stores the charging / discharging algorithm of this solution, providing core technical support for subsequent temperature compensation control. The temperature compensation control of this solution only applies to the constant current charging / discharging stage (not involving the constant voltage charging stage). By dynamically adjusting the current, the negative impact of temperature differences is offset, ensuring the consistency of the battery cells during the charging and discharging process.

[0048] See Figure 5 As shown, Figure 5 A flowchart of a temperature compensation control method provided in Embodiment 1 of this application is shown, wherein the temperature compensation control includes steps S501 to S503: S501: Obtains the temperature measurement value of the battery cell through a temperature sensor.

[0049] Specifically, the temperature sensor needs to be deployed inside the charging and discharging equipment to collect the actual operating temperature around the battery cell (i.e., the actual ambient temperature T) in real time.

[0050] The charging and discharging device's control unit stores the charging and discharging algorithm of this solution. The temperature data collected by the sensor will be transmitted to the control unit in real time, serving as the core basis for subsequent current adjustment.

[0051] S502: Calculate the real-time difference between the measured temperature value and the preset reference temperature.

[0052] Specifically, the preset reference temperature This refers to using a preset base current. (i.e., through) The calculated current is used to charge and discharge the product at the set standard charging and discharging temperature.

[0053] The real-time difference is calculated as "actual temperature". - Reference temperature "If the difference is positive, it means that the actual temperature of the battery cell is higher than the standard temperature; if it is negative, it means that the actual temperature of the battery cell is lower than the standard temperature."

[0054] S503: Based on the real-time difference, dynamically adjust the current value of the constant current charging or constant current discharging according to the preset compensation rules.

[0055] Specifically, the compensation rule adopts linear compensation, and the adjusted charging and discharging current calculation formula is as follows: .in, To increase the charge and discharge current after temperature compensation, To preset the base current, This is the temperature compensation coefficient. This is the actual temperature. The reference temperature is used, and the charging current and discharging current in this scheme can be set to different values ​​independently.

[0056] Taking a specific real-world scenario as an example: the temperature of other battery cells is 45℃ (i.e.) =45℃), basic charging current =1A, a certain battery cell has an actual temperature T=45.3℃ due to manufacturing process differences. If a temperature compensation coefficient is set... =0.05$, then the adjusted current =1-0.05*(45.3-45)=0.985A.

[0057] According to Joule's law ( For the heat generated, For current, For resistance, (For time), cells with higher temperatures can reduce heat generation by lowering the current, while cells with lower temperatures maintain a reasonable current, ultimately achieving dynamic temperature consistency between cells and further improving charging and discharging consistency.

[0058] In an optional implementation, the compensation rule is linear compensation, specifically calculated using the following formula: ;in, The adjusted current, The preset base current value, This is the temperature compensation coefficient. The temperature measurement value is... The reference temperature is [value].

[0059] Specifically, the definitions and functions of each parameter in the formula are as follows: To preset the base current, it is necessary to go through The calculation shows that N is a coefficient and C is the charge / discharge rate of the battery cell. The temperature compensation coefficient needs to be set in advance according to the cell type and charging / discharging scenario to ensure that the current adjustment range meets the cell performance requirements. T represents the actual temperature of the battery cell, which is collected in real time by the temperature sensor. The core logic of this formula is to offset the effect of temperature differences on current through linear adjustment, and different settings can be set for the charging and discharging processes. , and To adapt to the charging and discharging requirements at different stages.

[0060] In an optional implementation, calculating the rate of change of voltage based on voltage values ​​at at least two moments includes: Calculate the difference between the voltage values ​​at the at least two time points; Specifically, the voltage values ​​at the two moments correspond to the cell open-circuit voltage before discharge. and the open-circuit voltage of the battery cell after discharge The difference is calculated as follows: ".

[0061] This difference directly reflects the degree of voltage decay of the battery cell during rest or use, and is a key data point for evaluating the self-discharge performance of the battery cell.

[0062] The voltage change rate is obtained by dividing the difference by the time interval between the at least two moments.

[0063] Specifically, the time interval is the time difference between two voltage measurements. (If left to stand for 24 hours) =24h), the voltage change rate is the industry-standard K value, calculated using the following formula: In this plan, it is also referred to as It is mainly used to quantify the self-discharge rate of the battery cell.

[0064] In an optional implementation, calculating the rate of change of internal resistance based on internal resistance values ​​at at least two time points includes: Calculate the difference between the internal resistance values ​​at the at least two time points; Specifically, the internal resistance values ​​at the two moments correspond to the cell's internal resistance before discharge. and the internal resistance of the cell after discharge The difference is calculated as follows: ".

[0065] This difference reflects the change in the internal resistance of the cell after charge and discharge cycles. Generally speaking, an excessive increase in internal resistance means that the cell performance has degraded.

[0066] The internal resistance change rate is obtained by dividing the difference by the time interval between the at least two moments.

[0067] Specifically, the time interval needs to be the same as when calculating the rate of voltage change. To maintain consistency and ensure the validity of data comparisons, the formula for calculating the rate of change of internal resistance is: It is mainly used to quantify the rate of change of the internal resistance of the battery cell, which can make up for the shortcomings of the traditional K-value method that only focuses on voltage and ignores internal resistance.

[0068] In an optional implementation, see Figure 6 As shown, Figure 6 A flowchart of a cell screening and grouping method provided in Embodiment 1 of this application is shown, wherein the step of screening and / or grouping the cells according to the voltage change rate and the internal resistance change rate includes steps S601 to S604: S601: Multiply the voltage change rate by the first weighting coefficient to obtain the first weighting parameter.

[0069] Specifically, the rate of voltage change is as mentioned above. (Corresponding to K value), the first weighting coefficient is . The settings need to be adjusted according to the actual application scenario. For example, in scenarios where self-discharge performance is emphasized, the setting can be improved. The proportion, common settings are as follows =0.6.

[0070] The first weighted parameter is calculated as follows: Its function is to reflect the importance of voltage change rate in the overall evaluation.

[0071] S602: Multiply the internal resistance change rate by the second weighting coefficient to obtain the second weighting parameter.

[0072] Specifically, the rate of change of internal resistance is as mentioned above. The second weighting coefficient is . and When used together, the weighting ratio of the two can be flexibly adjusted, depending on the actual application requirements of the battery cell. Common settings include... =0.4.

[0073] The second weighting parameter is calculated as follows: Its function is to reflect the importance of the rate of change of internal resistance in the comprehensive evaluation and to ensure the integrity of the evaluation dimensions.

[0074] S603: Sum the first weighted parameter and the second weighted parameter to obtain the comprehensive evaluation value.

[0075] Specifically, if only one charge-discharge cycle is performed, the formula for calculating the comprehensive evaluation value S is " + If there are multiple charge-discharge cycles (such as 2 or 3 cycles), then a summation formula is needed. calculate.

[0076] in, This refers to the number of charge-discharge cycles. Voltage change rate corresponding to the i-th cycle , Rate of change of internal resistance corresponding to the i-th cycle .

[0077] Taking a specific scenario as an example: Cell 1 =1 (K value) ==2 (calculated by taking the absolute value), then the first weighted parameter = 0.6 × 1 = 0.6, the second weighted parameter = 0.4 × 2 = 0.8, and the comprehensive evaluation value S1 = 0.6 + 0.8 = 1.4; cell 2 =1.05、 ==11 (calculated by taking the absolute value), then the first weighted parameter = 0.6 × 1.05 = 0.63, the second weighted parameter = 0.4 × 11 = 4.4, and the comprehensive evaluation value S2 = 0.63 + 4.4 = 5.03.

[0078] It is evident that in the traditional K-value method, the K values ​​(1 and 1.05) of cell 1 and cell 2 are similar and easily misclassified as a group. However, this solution can clearly distinguish the performance differences between the two through comprehensive evaluation values ​​(1.4 and 5.03), resulting in higher screening accuracy.

[0079] S604: Screen and / or group the battery cells based on the comprehensive evaluation value.

[0080] Specifically, the screening process requires setting a threshold for the comprehensive evaluation value in advance. Cells with comprehensive evaluation values ​​within the threshold range are judged as qualified, while cells exceeding the threshold range (such as cells with excessive voltage drop or abnormal internal resistance changes) are judged as unqualified.

[0081] Grouping operations require pre-setting multiple performance ranges (such as the S-value ranges corresponding to "Excellent", "Good", and "Qualified"). Cells whose comprehensive evaluation values ​​fall into the same range are divided into the same performance level group to ensure that the voltage change and internal resistance change trends of cells in the same group are consistent, and to avoid the subsequent battery pack capacity decay and safety reduction due to differences in cell performance.

[0082] In an optional implementation, the screening and / or grouping of battery cells based on the comprehensive evaluation value includes: The comprehensive evaluation value is compared with a preset qualified threshold, and the battery cell whose comprehensive evaluation value meets the qualified threshold is determined to be a qualified battery cell.

[0083] Specifically, the acceptable threshold needs to be determined based on the cell's design standards and application scenarios (such as power batteries and energy storage batteries). For example, for a certain type of cell, the acceptable threshold can be set as "0.5≤S≤2.0". Cells with comprehensive evaluation values ​​within this range indicate that their self-discharge rate and internal resistance change rate are within a reasonable range, which can meet the performance requirements of subsequent battery pack assembly.

[0084] If S < 0.5, it is necessary to check whether there is a measurement error; if S > 2.0, it means that the performance of the battery cell is degrading too quickly and is judged as unqualified.

[0085] And / or, based on multiple preset performance ranges, cells whose comprehensive evaluation values ​​fall into different performance ranges are classified into corresponding different performance level groups.

[0086] Specifically, the division of performance ranges needs to be combined with actual application requirements. For example, in a certain scenario, three ranges can be set: "0.5≤S<1.0" (excellent group), "1.0≤S<1.5" (good group), and "1.5≤S≤2.0" (acceptable group).

[0087] Cells that fall into the "Excellent" group based on their overall evaluation can be used in devices with high performance requirements (such as high-end electric vehicles); cells in the "Good" group can be used in conventional devices; and cells in the "Acceptable" group can be used in low-power devices. This grouping method maximizes the utilization of cells with different performance characteristics while ensuring consistent cell performance within the same battery pack, thereby improving the overall reliability and lifespan of the battery pack.

[0088] Example 2 See Figure 7 As shown, Figure 7 This illustration shows a structural schematic diagram of a cell capacity testing device provided in Embodiment 2 of this application, wherein the device includes: The cycle execution module 701 is used to perform at least one cycle process including charging and discharging on the battery cell to be rated. The cell measurement module 702 is used to measure the voltage and internal resistance of the cell at at least two different times during the cyclic process. The rate of change calculation module 703 is used to calculate the rate of change of voltage based on the voltage values ​​at at least two moments, and to calculate the rate of change of internal resistance based on the internal resistance values ​​at at least two moments. The cell capacity assessment module 704 is used to screen and / or group cells according to the voltage change rate and the internal resistance change rate.

[0089] In an optional implementation, the device further includes a temperature compensation control module for: Temperature compensation control is performed during the constant current charging and / or constant current discharging phases of the cycle process. The temperature compensation control includes: The temperature measurement value of the battery cell is obtained through a temperature sensor; Calculate the real-time difference between the measured temperature value and the preset reference temperature; Based on the real-time difference, the current value of the constant current charging or constant current discharging is dynamically adjusted according to a preset compensation rule.

[0090] In an optional implementation, the compensation rule is linear compensation, specifically calculated using the following formula: ; in, The adjusted current, The preset base current value, This is the temperature compensation coefficient. The temperature measurement value is... The reference temperature is [value].

[0091] In an optional implementation, calculating the rate of change of voltage based on voltage values ​​at at least two moments includes: Calculate the difference between the voltage values ​​at the at least two time points; The voltage change rate is obtained by dividing the difference by the time interval between the at least two moments.

[0092] In an optional implementation, calculating the rate of change of internal resistance based on internal resistance values ​​at at least two time points includes: Calculate the difference between the internal resistance values ​​at the at least two time points; The internal resistance change rate is obtained by dividing the difference by the time interval between the at least two moments.

[0093] In an optional implementation, the step of screening and / or grouping the cells based on the voltage change rate and the internal resistance change rate includes: Multiplying the voltage change rate by the first weighting coefficient yields the first weighting parameter; Multiply the rate of change of internal resistance by the second weighting coefficient to obtain the second weighting parameter; The first weighted parameter and the second weighted parameter are summed to obtain the comprehensive evaluation value; The battery cells are screened and / or grouped based on the comprehensive evaluation values.

[0094] In an optional implementation, the screening and / or grouping of battery cells based on the comprehensive evaluation value includes: The comprehensive evaluation value is compared with a preset qualified threshold, and the battery cell whose comprehensive evaluation value meets the qualified threshold is determined to be a qualified battery cell; And / or, Based on multiple preset performance ranges, cells whose comprehensive evaluation values ​​fall into different performance ranges are classified into corresponding different performance level groups.

[0095] Example 3 Based on the same application concept, see [link / reference] Figure 8 As shown, Figure 8 This illustration shows a structural schematic diagram of a computer device provided in Embodiment 3 of this application, wherein, as shown... Figure 8 As shown, the computer device 800 provided in Embodiment 3 of this application includes: The system includes a processor 801, a memory 802, and a bus 803. The memory 802 stores machine-readable instructions that can be executed by the processor 801. When the computer device 800 is running, the processor 801 communicates with the memory 802 through the bus 803. When the machine-readable instructions are executed by the processor 801, they perform the steps of the cell capacity assessment method shown in Embodiment 1 above.

[0096] Example 4 Based on the same concept, this application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the cell capacity assessment method described in any of the above embodiments.

[0097] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and apparatus described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0098] The computer program product for cell capacity assessment provided in this application includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the methods described in the preceding method embodiments. For specific implementation details, please refer to the method embodiments, which will not be repeated here.

[0099] The cell capacity assessment device provided in this application embodiment can be specific hardware on a device or software or firmware installed on the device. The implementation principle and technical effects of the device provided in this application embodiment are the same as those in the foregoing method embodiments. For the sake of brevity, any parts not mentioned in the device embodiment can be referred to the corresponding content in the foregoing method embodiments. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can all be referred to the corresponding processes in the above method embodiments, and will not be repeated here.

[0100] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0101] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0102] In addition, the functional units in the embodiments provided in this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0103] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0104] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0105] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application. All should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A method for cell capacity rating, characterized in that, Includes the following steps: Perform at least one cycle of charging and discharging on the cells to be rated for capacity. At at least two different moments in the cyclic process, the voltage and internal resistance of the battery cell are measured. The rate of change of voltage is calculated based on the voltage values ​​at at least two times, and the rate of change of internal resistance is calculated based on the internal resistance values ​​at at least two times. Based on the voltage change rate and the internal resistance change rate, the battery cells are screened and / or grouped.

2. The method according to claim 1, characterized in that, The method further includes: Temperature compensation control is performed during the constant current charging and / or constant current discharging phases of the cycle process. The temperature compensation control includes: The temperature measurement value of the battery cell is obtained through a temperature sensor; Calculate the real-time difference between the measured temperature value and the preset reference temperature; Based on the real-time difference, the current value of the constant current charging or constant current discharging is dynamically adjusted according to a preset compensation rule.

3. The method according to claim 2, characterized in that, The compensation rule is linear compensation, and the adjusted current value is calculated using the following formula: ; in, The adjusted current, The preset base current value, This is the temperature compensation coefficient. The temperature measurement value is... The reference temperature is [value].

4. The method according to claim 1, characterized in that, The calculation of the voltage change rate based on voltage values ​​at at least two moments includes: Calculate the difference between the voltage values ​​at the at least two time points; The voltage change rate is obtained by dividing the difference by the time interval between the at least two moments.

5. The method according to claim 1, characterized in that, The calculation of the rate of change of internal resistance based on the internal resistance values ​​at at least two time points includes: Calculate the difference between the internal resistance values ​​at the at least two time points; The internal resistance change rate is obtained by dividing the difference by the time interval between the at least two moments.

6. The method according to claim 1, characterized in that, The step of screening and / or grouping battery cells based on the voltage change rate and the internal resistance change rate includes: Multiplying the voltage change rate by the first weighting coefficient yields the first weighting parameter; Multiply the rate of change of internal resistance by the second weighting coefficient to obtain the second weighting parameter; The first weighted parameter and the second weighted parameter are summed to obtain the comprehensive evaluation value; The battery cells are screened and / or grouped based on the comprehensive evaluation values.

7. The method according to claim 6, characterized in that, The process of screening and / or grouping battery cells based on the comprehensive evaluation value includes: The comprehensive evaluation value is compared with a preset qualified threshold, and the battery cell whose comprehensive evaluation value meets the qualified threshold is determined to be a qualified battery cell; And / or, Based on multiple preset performance ranges, cells whose comprehensive evaluation values ​​fall into different performance ranges are classified into corresponding different performance level groups.

8. A cell capacity rating device, characterized in that, The device includes: The cycle execution module is used to perform at least one cycle process including charging and discharging for the battery cells to be rated. A cell measurement module is used to measure the voltage and internal resistance of the cell at at least two different moments during the cyclic process. The rate of change calculation module is used to calculate the rate of change of voltage based on voltage values ​​at least two times and the rate of change of internal resistance based on internal resistance values ​​at least two times. A cell capacity assessment module is used to screen and / or group cells based on the voltage change rate and the internal resistance change rate.

9. A computer device, characterized in that, include: The device includes a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the computer device is running, the processor communicates with the memory via the bus. When the machine-readable instructions are executed by the processor, they perform the steps of the cell capacity assessment method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of the cell capacity assessment method as described in any one of claims 1 to 7.

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