Method and device for determining charging voltage of battery cell, electronic equipment and vehicle

Abstract

The application provides a method and device for determining charging voltage of an electric core, electronic equipment and vehicle, and relates to the technical field of electric cores. The method comprises the following steps: determining the release amount of pre-stored lithium in the positive active material according to the actual capacity of the target electric core; determining the charging voltage of the target electric core based on the release amount and a first mapping relationship. The first mapping relationship comprises the relationship between the charging cutoff voltage of the electric core and the delithiation ratio of the positive active material. The embodiments of the application are beneficial to improving the stability of the target electric core during use and prolonging the service life of the target electric core.

Description

Technical Field

[0001] This application relates to the field of battery cell technology, and in particular to a method, apparatus, electronic device, and vehicle for determining the charging voltage of a battery cell. Background Technology

[0002] A lithium-ion battery (LiB) is a secondary battery that stores and releases energy by repeatedly inserting and deintercalating lithium ions between the positive and negative electrodes. Due to its advantages such as high energy density, long lifespan, and no memory effect, lithium-ion batteries are widely used in electric vehicles, energy storage systems, and portable electronic devices.

[0003] In related technologies, lithium replenishing agents are generally used to replenish lithium on the positive electrode of lithium-ion batteries to compensate for lithium-ion losses during charge-discharge cycles. However, lithium replenishing agents generate a large amount of gas during charging, which not only leads to a decrease in the stability of lithium-ion batteries, but also increases the internal pressure of lithium-ion batteries, thereby accelerating the aging of lithium-ion batteries and reducing their lifespan. Summary of the Invention

[0004] The technical problem to be solved by this application is to provide a method, apparatus, electronic device and vehicle for determining the charging voltage of a battery cell, so as to solve the problem of decreased battery stability and reduced service life caused by using lithium replenishing agents to replenish lithium on the positive electrode of lithium-ion batteries in related technologies.

[0005] To solve the above problems, this application provides the following technical solution: This application proposes a method for determining the charging voltage of a battery cell. The method includes: determining the amount of lithium pre-stored in the positive electrode active material to be released based on the actual capacity of the target battery cell; and determining the charging voltage of the target battery cell based on the amount of lithium released and a first mapping relationship; wherein the first mapping relationship includes the relationship between the charging cut-off voltage of the battery cell and the lithium removal ratio of the positive electrode active material.

[0006] Further, determining the amount of lithium pre-stored in the positive electrode active material released based on the actual capacity of the target cell includes: when the actual capacity is less than or equal to a target threshold, or when the actual capacity is less than the target capacity, obtaining the delithiation ratio required to increase the actual capacity to the target capacity, wherein the target threshold is less than the target capacity; and determining the delithiation ratio as the amount of lithium pre-stored in the positive electrode active material released.

[0007] Further, determining the charging voltage of the target battery cell based on the release amount and the first mapping relationship includes: determining the charging cut-off voltage corresponding to the release amount from the first mapping relationship; and determining the charging cut-off voltage corresponding to the release amount as the charging voltage of the target battery cell.

[0008] Furthermore, the method further includes: determining pre-stored lithium from the positive electrode active material of the target battery cell based on the capacity decay rate of the target battery cell; and determining the initial charging voltage of the target battery cell based on the pre-stored lithium and a first mapping relationship.

[0009] Furthermore, the method further includes: determining the capacity recovery amount that the calibrated battery cell system can achieve by supplementing active lithium based on the loss rate of negative electrode active material, the loss rate of positive electrode active material, and the loss rate of active lithium under different battery cell capacities; the battery cell system of the calibrated battery cell is the same as the battery cell system of the target battery cell; and obtaining the relationship between the charging cut-off voltage of the calibrated battery cell and the delithiation ratio of the positive electrode active material based on the capacity recovery amount, thereby obtaining a first mapping relationship.

[0010] Furthermore, determining the capacity recovery amount that the calibrated battery cell system can achieve by supplementing active lithium based on the loss rate of negative electrode active material, the loss rate of positive electrode active material, and the loss rate of active lithium at different cell capacities includes: when the loss rate of active lithium is greater than the loss rate of negative electrode active material, and the loss rate of active lithium is greater than the loss rate of positive electrode active material, determining the capacity recovery amount that the calibrated battery cell system can achieve by supplementing active lithium based on the loss rate of negative electrode active material, the loss rate of positive electrode active material, and the loss rate of active lithium.

[0011] Further, when the active lithium loss rate is greater than the negative electrode active material loss rate, and the active lithium loss rate is greater than the positive electrode active material loss rate, determining the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium based on the negative electrode active material loss rate, the positive electrode active material loss rate, and the active lithium loss rate includes: calculating a first difference between the active lithium loss rate and the negative electrode active material loss rate when the active lithium loss rate is greater than the negative electrode active material loss rate, and the active lithium loss rate is greater than the positive electrode active material loss rate; calculating a second difference between the active lithium loss rate and the positive electrode active material loss rate; and determining the minimum value of the first difference and the second difference as the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium.

[0012] Further, the step of obtaining the relationship between the charging cut-off voltage of the calibrated cell and the lithium removal ratio of the positive electrode active material based on the capacity recovery amount to obtain the first mapping relationship includes: determining the pre-stored lithium corresponding to the positive electrode active material in the cell system of the calibrated cell based on the capacity recovery amount; and obtaining the relationship between the charging cut-off voltage of the calibrated cell and the lithium removal ratio of the positive electrode active material based on the pre-stored lithium corresponding to the positive electrode active material in the cell system of the calibrated cell to obtain the first mapping relationship.

[0013] This application also proposes a device for determining the charging voltage of a battery cell, the device comprising: a first determining module for determining the amount of lithium pre-stored in the positive electrode active material released based on the actual capacity of the target battery cell; and a second determining module for determining the charging voltage of the target battery cell based on the amount of lithium released and a first mapping relationship; wherein the first mapping relationship includes the relationship between the charging cut-off voltage of the battery cell and the lithium removal ratio of the positive electrode active material.

[0014] This application also proposes an electronic device comprising a memory and a processor, wherein the memory stores an executable program or instructions, and the processor executes the program or instructions to implement the method for determining the battery cell charging voltage as described above.

[0015] This application also proposes a vehicle comprising a battery cell and an electronic device as described above, wherein the electronic device determines the charging voltage of the battery cell using the battery cell charging voltage determination method described above.

[0016] Compared with related technologies, the embodiments of this application have the following advantages: The method for determining the charging voltage of a battery cell provided in this application determines the amount of pre-stored lithium released from the positive electrode active material of the target battery cell based on the actual capacity of the target battery cell, and determines the charging voltage of the target battery cell based on the amount of pre-stored lithium released and a first mapping relationship. When the target battery cell needs to be charged in the future, it can be charged based on the charging voltage of the target battery cell determined in this application embodiment. By releasing the pre-stored lithium in the positive electrode active material of the target battery cell, the lithium ion loss in the target battery cell is replenished, thereby increasing the actual capacity of the target battery cell to the target capacity. The replenishment of active lithium in the target battery cell can be achieved without adding lithium replenishing agent to the positive electrode of the target battery cell, which is beneficial to improving the stability of the target battery cell during use. Moreover, by controlling the amount of pre-stored lithium released, this application embodiment can control the degree of capacity recovery of the target battery cell, so that the capacity of the target battery cell decays at a lower decay rate or does not decay at all within a certain operating cycle, which is beneficial to slowing down the decay rate of the target battery cell's service life and extending the service life of the target battery cell.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0018] Figure 1 This application provides a step-by-step flowchart of a method for determining the charging voltage of a battery cell. Figure 1 ; Figure 2 This is a schematic diagram of the capacity decay curve of a target battery cell provided in an embodiment of this application. Figure 1 ; Figure 3 This is a schematic diagram of the capacity decay curve of a target battery cell provided in an embodiment of this application. Figure 2 ; Figure 4 This is a schematic diagram of the charging curve of a target battery cell containing lithium iron phosphate positive electrode active material provided in an embodiment of this application; Figure 5 This is a schematic diagram comparing the charging curves of a target battery cell containing lithium iron phosphate cathode active material and a target battery cell containing lithium nickel cobalt manganese ternary cathode active material, provided in the embodiments of this application. Figure 6 This application provides a step-by-step flowchart of a method for determining the charging voltage of a battery cell. Figure 2 ; Figure 7 This is a logic block diagram of a device for determining the charging voltage of a battery cell, provided in an embodiment of this application. Detailed Implementation

[0019] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Method Implementation Examples In related technologies, lithium replenishing agents are generally used to replenish lithium on the positive electrode of lithium-ion batteries in order to delay the degradation of the battery's lifespan. However, using lithium replenishing agents to replenish lithium on the positive electrode of lithium-ion batteries not only leads to gas generation problems that cause a decrease in the stability and lifespan of the lithium-ion battery, but also requires a corresponding increase in the amount of negative electrode active material, separator, and current collector in the lithium-ion battery. This makes the manufacturing process complex and increases the manufacturing cost of lithium-ion batteries.

[0021] In related technologies, to avoid gas generation problems caused by lithium replenishment agents, lithium-ion batteries are designed with a capacity reserve. The actual capacity of the lithium-ion battery is increased by a certain percentage compared to the required capacity. This percentage is called the reserve capacity. When the capacity of the lithium-ion battery decays due to lithium-ion loss, releasing the reserve capacity can increase the battery capacity. However, the capacity reserve design requires a corresponding increase in the amount of negative electrode active material, separator, and current collector in the lithium-ion battery, which leads to a significant decrease in the energy density of the lithium-ion battery.

[0022] Example 1: To address the above problems, this application provides a method for determining the charging voltage of a battery cell, referring to... Figure 1 The method may specifically include the following steps: Step S101: Determine the amount of lithium pre-stored in the positive electrode active material to be released based on the actual capacity of the target cell.

[0023] Step S102: Determine the charging voltage of the target battery cell based on the release amount and the first mapping relationship.

[0024] The method for determining the cell charging voltage provided in this application embodiment can be applied to any electronic device with charging control function, including but not limited to battery management system (BMS), charger controller, and power management integrated circuit (PMIC).

[0025] The first mapping relationship includes the relationship between the charging cut-off voltage of the battery cell and the lithium removal ratio of the positive electrode active material. Specifically, this relationship can be a one-to-one correspondence between the charging cut-off voltage and the lithium removal ratio of the positive electrode active material. The calibration battery cell used to calibrate the first mapping relationship has the same battery cell system as the target battery cell. The calibration battery cell is a standard battery cell with the same battery cell system as the target battery cell. The battery cell systems of the calibration battery cell and the target battery cell include a positive electrode sheet, a separator, and a negative electrode sheet. The negative electrode sheet includes a negative current collector and a negative active material layer disposed on the surface of the negative current collector. The positive electrode sheet includes a positive current collector and a positive active material layer disposed on the surface of the positive current collector. The negative active material layer includes negative active material, and the positive active material layer includes positive active material. Furthermore, the number of different types of positive active materials in the positive active material layer is greater than or equal to one.

[0026] The upper limit voltage of the positive electrode active material in the target cell is equal to the upper limit voltage of the positive electrode active material in the calibrated cell, and the initial charging voltage of the target cell is less than the upper limit voltage.

[0027] The positive electrode active material of the target battery cell includes pre-stored lithium. Pre-stored lithium refers to the active lithium that has not been extracted from the positive electrode active material of the target battery cell when the target battery cell is charged to the initial charging voltage. During the process of charging the target battery cell from the initial charging voltage to the upper limit voltage of the positive electrode active material, the proportion of active lithium extracted from the positive electrode active material is equal to the total amount of pre-stored lithium in the positive electrode active material of the target battery cell.

[0028] As an optional implementation, when the target cell is a fresh cell, relevant personnel can determine the initial charging voltage of the target cell based on its usable capacity. By inputting an initial charging voltage setting command to an electronic device, the device is instructed to control the charging process of the target cell according to the initial charging voltage specified in the command. This ensures that the target cell is charged at the initial charging voltage during its first charge. When the target cell is charged to the initial charging voltage, the pre-stored lithium in the positive electrode active material of the target cell will not be released; that is, the portion of lithium ions corresponding to the pre-stored lithium in the positive electrode active material will not be released. The target cell is de-intercalated from the positive electrode active material. As the actual capacity of the target cell decays, during the subsequent charging process of the target cell, the electronic device can perform the operations corresponding to steps S101 to S102 to determine the charging voltage of the target cell in real time. When the target cell needs to be charged, it is charged based on the charging voltage determined by step S102. This is done by releasing the pre-stored lithium in the positive electrode active material of the target cell to replenish the lithium ion loss in the target cell, thereby increasing the actual capacity of the target cell to the target capacity. This allows the capacity of the target cell to decay at a lower decay rate or not decay at all within a certain operating cycle.

[0029] It is understandable that by setting the initial charging voltage of the target battery cell, the pre-stored lithium in the positive electrode active material of the target battery cell can be achieved.

[0030] It should be noted that the usable capacity of the target battery cell is less than its rated capacity; the usable capacity of the target battery cell refers to the initial capacity of the target battery cell to meet actual usage requirements, while the rated capacity of the target battery cell refers to the capacity that the target battery cell can achieve when charged to its upper limit voltage.

[0031] In some embodiments, the pre-stored lithium is determined based on the capacity decay rate of the target cell; in other embodiments, the pre-stored lithium is determined based on both the capacity decay rate of the target cell and the capacity recovery achievable by the target cell through replenishment of active lithium. The capacity decay rate of the target cell is the desired capacity decay rate of the target cell specified by relevant personnel.

[0032] Specifically, in step S101, the electronic device can obtain the actual capacity of the target cell in real time; then, based on the actual capacity, it determines the proportion of active lithium required to increase the capacity of the target cell from the actual capacity to the target capacity, and determines the proportion of active lithium as the amount of lithium pre-stored in the positive electrode active material to be released.

[0033] The target capacity can be equal to or less than the usable capacity of the target battery cell. The target capacity can be determined based on the charge / discharge cycle period of the target battery cell and a pre-specified capacity decay rate. For example, if the target battery cell needs to achieve no capacity decay in the first year, the target capacity is equal to the usable capacity of the target battery cell during the first year's charge / discharge cycles. If the target battery cell needs to achieve a 2% capacity decay in the second year, the target capacity is 98% of the usable capacity of the target battery cell during the second year's charge / discharge cycles.

[0034] The amount of pre-stored lithium released by the electronic device as determined in step S101 is less than or equal to the total amount of pre-stored lithium in the positive electrode active material.

[0035] In step S102, firstly, the electronic device acquires a pre-stored first mapping relationship; then, using the pre-stored lithium release amount as the key value, it searches for the charging cut-off voltage corresponding to the release amount in the first mapping relationship, and determines the charging cut-off voltage as the charging voltage of the target cell.

[0036] The charging voltage determined in step S102 is the charging cutoff voltage of the target battery cell. The charging voltage determined in step S102 is greater than or equal to the initial charging voltage of the target battery cell, and the charging voltage determined in step S102 is less than or equal to the upper limit voltage of the positive electrode active material in the target battery cell.

[0037] In some embodiments, the number of pre-stored first mapping relationships is at least two, different first mapping relationships correspond to different cell capacities, and the cell capacity corresponding to the first mapping relationship is marked in the first mapping relationship. Before step S102, the electronic device can look up the pre-stored first mapping relationship based on the actual capacity of the target cell, make the cell capacity marked in the first mapping relationship equal to the actual capacity, or determine the first mapping relationship in the first mapping relationship whose cell capacity is closest to the actual capacity as the first mapping relationship corresponding to the actual capacity of the target cell, and perform step S102 based on the first mapping relationship and the release amount.

[0038] If the charging voltage determined in step S102 is greater than the initial charging voltage of the target cell, during the subsequent charging process of the target cell, the charging voltage for charging the target cell can be increased to release some or all of the pre-stored lithium in the positive electrode active material of the target cell, replenish the lithium ion loss in the target cell, and increase the target cell from the actual capacity to the target capacity.

[0039] In some embodiments, the first mapping relationship includes a delithiation ratio that is equal to or close to the amount of pre-stored lithium released. In some embodiments, in step S102, the electronic device can determine the charging cutoff voltage corresponding to the delithiation ratio equal to the amount of release in the first mapping relationship as the charging voltage of the target cell; in other embodiments, in step S102, the electronic device can determine the charging cutoff voltage corresponding to the delithiation ratio closest to the amount of release in the first mapping relationship as the charging voltage of the target cell.

[0040] If the amount of pre-stored lithium released as determined in step S101 is less than the total amount of pre-stored lithium in the positive electrode active material, and the charging voltage determined in step S102 is less than the upper limit voltage of the positive electrode active material in the target cell, then during the charging process of the target cell based on the charging voltage determined in step S102, a portion of the pre-stored lithium in the positive electrode active material of the target cell corresponding to the amount of release will be released. If the amount of pre-stored lithium released as determined in step S101 is equal to the total amount of pre-stored lithium in the positive electrode active material, and the charging voltage determined in step S102 is equal to the upper limit voltage of the positive electrode active material in the target cell, then during the charging process of the target cell based on the charging voltage determined in step S102, all the pre-stored lithium in the positive electrode active material of the target cell will be released.

[0041] This application provides a method for determining the charging voltage of a battery cell. Based on the actual capacity of the target battery cell, the method determines the amount of pre-stored lithium released from the positive electrode active material of the target battery cell. Based on the amount of pre-stored lithium released and a first mapping relationship, the method determines the charging voltage of the target battery cell. When subsequent charging of the target battery cell is required, it can be charged based on the charging voltage determined in this application. This releases the pre-stored lithium in the positive electrode active material of the target battery cell, replenishing the lithium-ion losses in the target battery cell and thereby increasing the actual capacity of the target battery cell to the target capacity. In this process, it is not necessary to add a lithium replenishing agent to the positive electrode of the target battery cell to replenish the active lithium in the target battery cell, avoiding the problems of decreased cell stability and reduced lifespan caused by the gas generation of the lithium replenishing agent. This is beneficial to improving the stability and safety of the target battery cell during use. Furthermore, by controlling the amount of pre-stored lithium released, this application can control the degree of capacity recovery of the target battery cell, so that the capacity of the target battery cell decays at a low rate or not at all within a certain operating cycle, thereby improving the cell's state of health. Health (SOH) decays at a low rate or not at all within a certain operating cycle, which helps to slow down the decay rate of the target cell's lifespan and extend the lifespan of the target cell.

[0042] Furthermore, referring to Table 1, a comparison table of process parameters for mitigating the degradation of the lifespan of a target battery cell provided by an embodiment of this application is shown. Compared with related battery cells 1 to 3, the embodiment of this application can not only compensate for the capacity degradation of the target battery cell caused by lithium consumption, mitigate the degradation of the lifespan of the target battery cell, and extend the lifespan of the target battery cell, but also reduce the manufacturing difficulty and manufacturing cost of the target battery cell, and the reduction in the energy density of the target battery cell is relatively low.

[0043] Table 1

[0044] Where a is the amount of lithium removed from the positive electrode active material corresponding to the cell's capacity, and a is greater than 0; n is the ratio between the pre-stored lithium and a, and n is greater than 0 and less than 1; a1 is the amount of lithium replenishing agent; b1 is the amount of negative electrode active material set corresponding to the lithium replenishing agent; a1, b1, b, c, and d are all greater than 0.

[0045] Example 2, in an optional embodiment of this application, step S101, determining the release amount of pre-stored lithium in the positive electrode active material based on the actual capacity of the target battery cell, includes: Step S1011: If the actual capacity is less than or equal to the target threshold, or if the actual capacity is less than the target capacity, obtain the delithiation ratio required to increase the actual capacity to the target capacity.

[0046] Step S1012: Determine the delithiation ratio as the amount of lithium released from the pre-stored lithium in the positive electrode active material.

[0047] In some embodiments, the electronic device can determine the amount of lithium pre-stored in the positive electrode active material released through the operations corresponding to steps S1011 to S1012 when the actual capacity of the target battery cell is less than or equal to the target threshold. In some embodiments, the electronic device can determine the amount of lithium pre-stored in the positive electrode active material released through the operations corresponding to steps S1011 to S1012 when the actual capacity of the target battery cell is less than the target capacity. Wherein, the target threshold is less than the target capacity.

[0048] In practical applications, the timing of steps S1011 to S1012 can be determined based on the pre-stored lithium release rule of the target battery cell. The pre-stored lithium release rule is used to indicate the release timing of pre-stored lithium in the positive electrode active material of the target battery cell, and the pre-stored lithium release rule includes at least one of intermittent release and continuous release.

[0049] Reference Figure 2 This illustration shows a schematic of the capacity decay curve of a target battery cell provided in an embodiment of this application. Figure 1 The pre-stored lithium release rule is intermittent release. When the actual capacity of the target cell is less than or equal to the target threshold, the electronic device executes steps S1011 to S1012. Specifically, when the actual capacity of the target cell decays to less than or equal to the target threshold, the electronic device can execute the operations corresponding to steps S1011 to S1012 to determine the amount of pre-stored lithium to be released, and then execute step S102 to determine the charging voltage of the target cell. When it is necessary to charge the target cell, the target cell is charged based on the charging voltage of the target cell determined by step S102 to release the portion of pre-stored lithium corresponding to the amount released in the positive electrode active material of the target cell, replenish the lithium-ion loss of the target cell, and increase the target cell from the actual capacity to the target capacity.

[0050] Specifically, when the amount of pre-stored lithium released is less than the total amount of pre-stored lithium in the positive electrode active material, the target cell includes at least two pre-stored lithium release cycles. The target thresholds corresponding to each pre-stored lithium release cycle may be equal or unequal. Figure 2 This illustrates the case where the target thresholds for each pre-stored lithium release cycle are not equal; furthermore, the target capacities for each pre-stored lithium release cycle can be equal or unequal. Figure 2 This illustrates the case where the target capacity corresponding to each pre-stored lithium release cycle is not equal.

[0051] A typical battery cell refers to a cell that has the same cell system as the target cell, does not have pre-stored lithium in its positive electrode active material, and has the same capacity as the target cell. For example... Figure 2 As shown, this embodiment of the application controls the intermittent release of pre-stored lithium in the positive electrode active material of the target cell, which can increase the capacity of the target cell from the actual capacity to the target capacity in stages. This helps to slow down the degradation process of the target cell's lifespan and extend the lifespan of the target cell.

[0052] Reference Figure 3 This illustration shows a schematic of the capacity decay curve of a target battery cell provided in an embodiment of this application. Figure 2 The pre-stored lithium release rule is a continuous release. When the actual capacity of the target cell is less than the target capacity, the electronic device executes steps S1011 to S1012. Specifically, when the actual capacity of the target cell is less than the target capacity, the electronic device can execute the operations corresponding to steps S1011 to S1012 to determine the amount of pre-stored lithium to be released, and then execute step S102 to determine the charging voltage of the target cell. When it is necessary to charge the target cell, the target cell is charged based on the charging voltage of the target cell determined by step S102, so as to release the portion of pre-stored lithium corresponding to the release amount in the positive electrode active material of the target cell, replenish the lithium ion loss in the target cell, and increase the target cell from the actual capacity to the target capacity.

[0053] Figure 3 The comparison between the capacity decay curve of the target cell and the capacity decay curve of a typical cell is shown in an application scenario where the capacity decay rate of the target cell is 0. In this embodiment, by controlling the continuous release of pre-stored lithium in the positive electrode active material of the target cell, the capacity of the target cell can be continuously increased from the actual capacity to the target capacity, so that the capacity of the target cell does not decay before the pre-stored lithium is exhausted.

[0054] In this embodiment of the application, if the actual capacity of the target cell is greater than or equal to the target threshold, it indicates that the target cell does not currently need to increase its capacity by releasing pre-stored lithium. The electronic device does not perform the operations corresponding to steps S1011 to S1012 until the actual capacity of the target cell is less than or equal to the target threshold, or the actual capacity is less than the target capacity, and then performs the operations corresponding to steps S1011 to S1012.

[0055] Specifically, in step S1011, if the actual capacity is less than or equal to the target threshold, or if the actual capacity is less than the target capacity, the electronic device can calculate the delithiation ratio required to increase the target cell's capacity from the actual capacity to the target capacity based on the actual capacity and the target capacity. (1) in, The percentage of lithium removal is expressed as % Indicates the target capacity, in mAh; Indicates actual capacity, in mAh; This represents the theoretical specific capacity of the positive electrode active material, expressed in mAh / g. This indicates the total mass of the positive electrode active material, expressed in grams. This represents the Coulomb efficiency, with a value ranging from 0.95 to 0.99. It is understandable that... and For characteristic parameters related to the positive electrode active material, given that the positive electrode active material in the target cell is determined, and It is a fixed value.

[0056] In step S1012, the electronic device can determine the delithiation ratio determined in step S1011 as the amount of lithium pre-stored in the positive electrode active material of the target cell.

[0057] The method for determining the charging voltage of a battery cell provided in this application embodiment allows an electronic device to determine the delithiation ratio required to increase the actual capacity to the target capacity when the actual capacity is less than or equal to the target threshold, or when the actual capacity is less than the target capacity. This delithiation ratio determines the amount of pre-stored lithium to be released. The relevant parameters for obtaining the delithiation ratio are easy to obtain and the process is simple, which helps reduce resource consumption in determining the amount of pre-stored lithium to be released and shortens the time required to do so. Furthermore, this application embodiment can control the degree of capacity recovery of the target battery cell according to the requirements of different pre-stored lithium release rules, so that the capacity of the target battery cell decays at a lower decay rate or does not decay at all within a certain operating cycle, improving the flexibility and operability of this application embodiment.

[0058] Example 3, in an optional embodiment of this application, step S102, determining the charging voltage of the target cell based on the release amount and the first mapping relationship, includes: Step S1021: Determine the charging cutoff voltage corresponding to the release amount from the first mapping relationship.

[0059] Step S1022: Determine the charging cutoff voltage corresponding to the release amount as the charging voltage of the target cell.

[0060] In this embodiment, the electronic device uses the charging cutoff voltage corresponding to the release amount in the first mapping relationship as the charging voltage of the target battery cell. By controlling the charging voltage of the target battery cell, the release amount of pre-stored lithium in the positive electrode active material of the target battery cell is controlled, thereby achieving precise control of the capacity recovery degree of the target battery cell. This is beneficial to improving the controllability of the capacity decay rate of the target battery cell, so that the capacity of the target battery cell decays at a lower decay rate or does not decay within a certain operating cycle, which is beneficial to slowing down the decay rate of the target battery cell's lifespan and extending the lifespan of the target battery cell.

[0061] In step S1021, the electronic device can match the amount of pre-stored lithium released with the delithiation ratio in the first mapping relationship, and determine the charging cutoff voltage corresponding to the delithiation ratio in the first mapping relationship that is equal to the amount of lithium released as the charging cutoff voltage corresponding to the amount of lithium released. In some embodiments, if the first mapping relationship does not include a delithiation ratio equal to the amount of lithium released, the charging cutoff voltage corresponding to the delithiation ratio in the first mapping relationship that is closest to the amount of lithium released can be determined as the charging cutoff voltage corresponding to the amount of lithium released.

[0062] In step S1022, the electronic device can determine the charging cutoff voltage determined in step S1021 as the charging voltage of the target battery cell. When it is necessary to charge the target battery cell, by charging the target battery cell to the charging cutoff voltage corresponding to the release amount, the positive electrode active material of the target battery cell can be promoted to release the pre-stored lithium corresponding to the release amount, replenishing the lithium ion loss in the target battery cell, and increasing the capacity of the target battery cell from the actual capacity to the target capacity.

[0063] Example 4, in an optional embodiment of this application, the method for determining the cell charging voltage provided in this application embodiment may further include: Step A11: Determine the pre-stored lithium from the positive electrode active material of the target battery cell based on the capacity decay rate of the target battery cell.

[0064] Step A12: Determine the initial charging voltage of the target battery cell based on the pre-stored lithium and the first mapping relationship.

[0065] In this embodiment of the application, before step S101, the electronic device can perform the operations corresponding to steps A11 to A12. Based on the capacity decay rate of the target battery cell, the pre-stored lithium and the initial charging voltage of the target battery cell are determined in the positive electrode active material of the target battery cell. The total amount of pre-stored lithium in the target battery cell can be flexibly adjusted, thereby realizing flexible control over the degree of capacity recovery of the target battery cell. This allows the capacity of the target battery cell to decay at a lower decay rate or not decay at all within a certain operating cycle, thus extending the service life of the target battery cell.

[0066] Specifically, relevant personnel can input a capacity decay rate setting command into the electronic device. The capacity decay rate setting command is used to indicate the capacity decay rate of the target cell within a certain operating cycle. The electronic device can use the capacity decay rate indicated by the capacity decay rate setting command as the capacity decay rate of the target cell.

[0067] In step A11, the electronic device can determine the portion of active lithium in the positive electrode active material whose mass percentage is less than or equal to the capacity recovery amount of the target cell, based on the capacity decay rate. This portion is defined as pre-stored lithium in the positive electrode active material. The capacity recovery amount of the target cell refers to the maximum capacity recovery achievable by replenishing the active lithium. The total amount of pre-stored lithium refers to the mass percentage of pre-stored lithium in the maximum extractable lithium ions of the positive electrode active material, and this total amount is less than or equal to the capacity recovery amount of the target cell.

[0068] Specifically, when the capacity decay rate is less than a first threshold, it indicates that a larger amount of pre-stored lithium is needed to replenish the active lithium lost by the target cell during charge-discharge cycles. In this scenario, the electronic device can define the portion of active lithium in the positive electrode active material whose mass percentage equals the capacity recovery amount of the target cell is the pre-stored lithium in the positive electrode active material. When the capacity decay rate is greater than or equal to the first threshold, it indicates that less active lithium needs to be replenished to the target cell during charge-discharge cycles. In this scenario, the electronic device can define the portion of active lithium in the positive electrode active material whose mass percentage is less than the capacity recovery amount of the target cell is the pre-stored lithium in the positive electrode active material.

[0069] The first threshold is a critical decay rate value used to distinguish the capacity decay rate of the target cell. For example, the first threshold is 2% / year. If the capacity decay rate setting instruction indicates that the capacity decay rate of the target cell in the first year is 0 / year, the electronic device can determine the portion of active lithium in the positive electrode active material whose mass percentage is equal to the capacity recovery amount of the target cell as the pre-stored lithium in the positive electrode active material. If the capacity decay rate setting instruction indicates that the capacity decay rate of the target cell in the first year is 3% / year, the electronic device can determine the portion of active lithium in the positive electrode active material whose mass percentage is less than the capacity recovery amount of the target cell as the pre-stored lithium in the positive electrode active material.

[0070] When pre-stored lithium is determined in the positive electrode active material of the target cell through step A11, the usable capacity of the target cell is determined accordingly; thereafter, the electronic device can obtain the charging voltage when the fresh target cell is charged to the usable capacity, and determine the charging voltage as the initial charging voltage of the target cell.

[0071] Example 5, in an optional embodiment of this application, the method for determining the cell charging voltage provided in this application embodiment may further include: Step B11: Based on the loss rate of negative electrode active material, loss rate of positive electrode active material, and loss rate of active lithium of the calibrated cell at different cell capacities, determine the capacity recovery amount that the cell system of the calibrated cell can achieve by supplementing active lithium.

[0072] Step B12: Based on the capacity recovery amount, obtain the relationship between the charging cutoff voltage of the calibrated cell and the delithiation ratio of the positive electrode active material to obtain the first mapping relationship.

[0073] In this embodiment of the application, a first mapping relationship can be obtained by using a calibrated battery cell with the same battery cell system as the target battery cell through the operations corresponding to steps B11 to B12.

[0074] Specifically, before step B11, the electronic device can start from the first charge and discharge of the calibrated cell and sequentially obtain the loss rate of the negative electrode active material, the loss rate of the positive electrode active material, and the loss rate of the active lithium at at least two different cell capacities, and construct a second mapping relationship between the cell capacity of the calibrated cell and the loss rates of the negative electrode active material, the positive electrode active material, and the active lithium; in the second mapping relationship, each cell capacity corresponds to a set of loss rates of the negative electrode active material, the positive electrode active material, and the active lithium.

[0075] The loss rates of negative electrode active materials, positive electrode active materials, and active lithium are all expressed as percentages (%). The negative electrode active material loss rate refers to the ratio of the mass of the negative electrode active material in a calibrated cell at any cell capacity to the mass of the negative electrode active material in a fresh cell state. The positive electrode active material loss rate refers to the ratio of the mass of the positive electrode active material in a calibrated cell at any cell capacity to the mass of the positive electrode active material in a fresh cell state. The active lithium loss rate refers to the ratio of the mass of active lithium in a calibrated cell at any cell capacity to the mass of active lithium in a fresh cell state.

[0076] Cell capacity refers to the amount of charge that a cell can release under certain conditions (e.g., current, temperature, charge / discharge cutoff voltage). In this embodiment, cell capacity is expressed in ampere-hours (Ah) or milliampere-hours (mAh).

[0077] The calibrated cell capacity is the actual capacity of the calibrated cell at any given moment. It can be understood that as the number of charge-discharge cycles of the calibrated cell increases, the loss rate of the negative electrode active material, the loss rate of the positive electrode active material, and the loss rate of active lithium in the calibrated cell continuously increase, leading to a continuous decrease in the calibrated cell capacity, which in turn leads to a decline in the health status of the calibrated cell.

[0078] Cell health status refers to the degree of health of the cell's current state relative to its fresh state. In some embodiments, the ratio of the calibrated cell's cell capacity to its capacity in its fresh state can be determined as the actual cell health status of the calibrated cell; for example, if the calibrated cell's cell capacity is 80Ah and its capacity in its fresh state is 100Ah, then the actual cell health status of the calibrated cell is 80%. In other embodiments, the difference between 1 and the maximum value among the negative electrode active material loss rate, positive electrode active material loss rate, and active lithium loss rate of the calibrated cell at any cell capacity can be determined as the actual cell health status of the calibrated cell at that cell capacity. (2) in, This indicates the actual health status of the battery cell, expressed as a percentage (%). This indicates the loss rate of the negative electrode active material, expressed in % . This indicates the loss rate of the positive electrode active material, expressed in % . This represents the active lithium loss rate, expressed in percent.

[0079] In step B11, for the loss rate of negative electrode active material, positive electrode active material, and active lithium at any cell capacity of the calibrated cell, firstly, the electronic device determines the maximum value among the loss rates of negative electrode active material and positive electrode active material. Then, the electronic device calculates the third difference between the active lithium loss rate and the maximum value. If the third difference is greater than 0, it indicates that the active lithium loss is dominant in the calibrated cell at that cell capacity, and the capacity can be recovered by supplementing active lithium. In this scenario, the electronic device can determine the third difference as the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium at that cell capacity. If the third difference is less than or equal to 0, it indicates that the calibrated cell is not dominated by active lithium loss at that cell capacity, and the capacity loss caused by the loss of negative electrode active material and positive electrode active material cannot be overcome by supplementing active lithium, thus the capacity cannot be recovered by supplementing active lithium. In this scenario, the electronic device can determine the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium at that cell capacity as 0.

[0080] The capacity recovery that the calibrated cell system can achieve by supplementing active lithium refers to the maximum capacity recovery that the calibrated cell system can achieve by supplementing active lithium.

[0081] Understandably, through step B11, the electronic device can obtain the capacity recovery that the calibrated cell system can achieve by supplementing active lithium at at least two different cell capacities.

[0082] In step B12, if the capacity recovery amount determined in step B11 is greater than 0, firstly, the electronic device obtains the upper limit voltage of the positive electrode active material in the calibrated cell; then, the upper limit voltage and at least two voltages lower than the upper limit voltage are used as charging cut-off voltage calibration points to obtain the lithium removal ratio of the positive electrode active material of the calibrated cell under different charging cut-off voltages, thereby establishing a one-to-one correspondence between the charging cut-off voltage of the calibrated cell and the lithium removal ratio of the positive electrode active material under different cell capacities, thus obtaining the first mapping relationship.

[0083] The lithium removal ratio refers to the ratio of the actual amount of lithium ions removed from the positive electrode active material during the charging process of the calibrated cell to the theoretical maximum amount of lithium ions that the positive electrode active material can remove, expressed as a percentage.

[0084] The upper limit voltage of a positive electrode active material refers to the highest operating voltage at which the positive electrode active material can stably participate in the lithium-ion intercalation / deintercalation reaction without irreversible damage to its crystal structure. The upper limit voltage of a positive electrode active material is an inherent property of the positive electrode active material.

[0085] In the first mapping relationship, the charging cutoff voltage corresponds one-to-one with the lithium removal ratio of the positive electrode active material, and the higher the charging voltage, the higher the lithium removal ratio of the positive electrode active material; the electronic device can obtain the first mapping relationship corresponding to different cell capacities through step B12.

[0086] In this embodiment of the application, each cell capacity corresponds to a first mapping relationship. The first mapping relationship can be stored in the form of a mapping relationship table, and the cell capacity corresponding to the first mapping relationship is marked in the first mapping relationship.

[0087] When the capacity recovery amount is equal to 0, it indicates that the cell system of the calibrated cell is not dominated by active lithium loss at the cell capacity and the capacity cannot be recovered by replenishing active lithium. In this scenario, the electronic device does not need to perform the operation of step B12 and sets the first mapping relationship corresponding to the cell capacity to empty.

[0088] In this embodiment of the application, after the electronic device obtains the first mapping relationship through step B12, it can store the first mapping relationship.

[0089] Before step S102, the electronic device can look up a pre-stored first mapping relationship based on the actual capacity of the target battery cell. The battery cell capacity marked in the first mapping relationship is equal to the actual capacity, or the first mapping relationship in the first mapping relationship that is closest to the actual capacity is determined as the first mapping relationship corresponding to the actual capacity of the target battery cell. Based on the first mapping relationship and the release amount, step S102 is executed to determine the charging voltage of the target battery cell. This helps to improve the accuracy of the charging voltage of the target battery cell determined by the electronic device based on the first mapping relationship and the release amount. When it is necessary to charge the target battery cell, the target battery cell is charged based on the charging voltage determined by step S102. By releasing the pre-stored lithium in the positive electrode active material of the target battery cell, the lithium ion loss in the target battery cell is replenished, and the actual capacity of the target battery cell is increased to the target capacity. This allows the capacity of the target battery cell to decay at a lower decay rate or not decay at all within a certain operating cycle, which helps to extend the service life of the target battery cell.

[0090] Example 6, in an optional embodiment of this application, step B11, which involves determining the capacity recovery achievable by supplementing active lithium in the cell system of the calibrated cell based on the loss rate of the negative electrode active material, the loss rate of the positive electrode active material, and the loss rate of active lithium at different cell capacities, includes: Step B111: When the active lithium loss rate is greater than the negative electrode active material loss rate, and the active lithium loss rate is greater than the positive electrode active material loss rate, determine the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium based on the negative electrode active material loss rate, the positive electrode active material loss rate, and the active lithium loss rate.

[0091] In this embodiment, when the active lithium loss rate is greater than the negative electrode active material loss rate and the active lithium loss rate is greater than the positive electrode active material loss rate, the electronic device can determine the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium based on the negative electrode active material loss rate, the positive electrode active material loss rate, and the active lithium loss rate. This not only simplifies the process of determining the capacity recovery amount but also helps to improve the reliability of the capacity recovery amount and the accuracy of the first mapping relationship calibrated based on the capacity recovery amount. This improves the accuracy of the charging voltage of the target cell determined based on the first mapping relationship, thereby improving the effectiveness of charging the target cell based on the charging voltage of the target cell to increase the actual capacity of the target cell to the target capacity.

[0092] Specifically, when the active lithium loss rate is greater than the negative electrode active material loss rate and the positive electrode active material loss rate, it indicates that the cell system of the calibrated cell is dominated by active lithium loss at that cell capacity, and the method of restoring capacity by supplementing active lithium is effective. In this scenario, the electronic device can execute step B111 to determine the amount of capacity recovery that the calibrated cell system can achieve by supplementing active lithium based on the negative electrode active material loss rate, the positive electrode active material loss rate and the active lithium loss rate.

[0093] If the active lithium loss rate is less than or equal to the negative electrode active material loss rate, and / or the active lithium loss rate is less than or equal to the positive electrode active material loss rate, it indicates that the cell system of the calibrated cell is not dominated by active lithium loss at this cell capacity, and the effect of replenishing active lithium to restore capacity is limited. In this scenario, the electronic device can determine that the cell system of the calibrated cell cannot restore capacity by replenishing active lithium. The electronic device can determine that the capacity recovery amount that the cell system of the calibrated cell can achieve by replenishing active lithium at this cell capacity is 0. In this scenario, the electronic device does not need to perform the operation of step B12 and sets the first mapping relationship corresponding to the cell capacity to empty.

[0094] Example 7, in an optional embodiment of this application, step B111, where the active lithium loss rate is greater than the negative electrode active material loss rate, and the active lithium loss rate is greater than the positive electrode active material loss rate, determines the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium based on the negative electrode active material loss rate, the positive electrode active material loss rate, and the active lithium loss rate, including: Step B1111: When the active lithium loss rate is greater than the negative electrode active material loss rate, and the active lithium loss rate is greater than the positive electrode active material loss rate, calculate the first difference between the active lithium loss rate and the negative electrode active material loss rate.

[0095] Step B1112: Calculate the second difference between the active lithium loss rate and the positive electrode active material loss rate.

[0096] Step B1113: Determine the minimum value between the first difference and the second difference as the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium.

[0097] In this embodiment of the application, when the active lithium loss rate is greater than the negative electrode active material loss rate and the active lithium loss rate is greater than the positive electrode active material loss rate, the electronic device can execute steps B1111 and B1112 to calculate the first difference between the active lithium loss rate and the negative electrode active material loss rate, and the second difference between the active lithium loss rate and the positive electrode active material loss rate, respectively. Then, in step B1113, the minimum value of the first difference and the second difference is determined as the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium. The calculation parameters are easy to obtain and the calculation process is simple, which is beneficial to improve the accuracy of the capacity recovery amount while improving the efficiency of determining the capacity recovery amount.

[0098] Specifically, when the active lithium loss rate is greater than the negative electrode active material loss rate, and the active lithium loss rate is greater than the positive electrode active material loss rate, the electronic device can determine the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium, based on the negative electrode active material loss rate, the positive electrode active material loss rate, and the active lithium loss rate, using the following formula: (3) in, This indicates the amount of capacity restored, expressed in % (%). This represents the first difference, expressed in % %. This represents the second difference, expressed as a percentage.

[0099] Example 8, in an optional embodiment of this application, step B12, which involves obtaining the relationship between the charging cutoff voltage of the calibrated cell and the lithium removal ratio of the positive electrode active material based on the capacity recovery amount, to obtain a first mapping relationship, includes: Step B121: Based on the capacity recovery amount, determine the pre-stored lithium corresponding to the positive electrode active material in the cell system of the calibrated cell.

[0100] Step B122: Based on the pre-stored lithium corresponding to the positive electrode active material in the calibrated cell system, obtain the relationship between the charging cut-off voltage of the calibrated cell and the lithium removal ratio of the positive electrode active material, and obtain the first mapping relationship.

[0101] In this embodiment of the application, during the process of obtaining the first mapping relationship based on the capacity recovery amount, the electronic device can first execute step B121 to determine the pre-stored lithium corresponding to the positive electrode active material in the cell system of the calibrated cell; then execute step B122 to obtain the relationship between the charging cut-off voltage of the calibrated cell and the delithiation ratio of the positive electrode active material based on the pre-stored lithium, and obtain the first mapping relationship.

[0102] Specifically, in step B121, the electronic device can determine the portion of active lithium in the positive electrode active material of the calibrated cell system that has a mass percentage less than or equal to the capacity recovery amount as the pre-stored lithium corresponding to the positive electrode active material in the calibrated cell system.

[0103] It should be noted that the calibration cell is a standard cell in which the positive electrode active material does not contain pre-stored lithium, while the pre-stored lithium in the positive electrode active material of the calibration cell refers to the pre-stored lithium that can be set in the positive electrode active material of a cell with the same cell system as the calibration cell.

[0104] In some embodiments, the mass percentage of pre-stored lithium in the maximum extractable lithium ions of the positive electrode active material is equal to the capacity recovery amount. For example, when the capacity recovery amount is 20%, the mass percentage of pre-stored lithium in the maximum extractable lithium ions of the positive electrode active material is equal to 20%. In other embodiments, the mass percentage of pre-stored lithium in the maximum extractable lithium ions of the positive electrode active material is less than the capacity recovery amount. For example, when the capacity recovery amount is 20%, the mass percentage of pre-stored lithium in the maximum extractable lithium ions of the positive electrode active material is equal to 10%.

[0105] This application embodiment controls the mass percentage of pre-stored lithium in the maximum extractable lithium ions of the positive electrode active material to be less than or equal to the capacity recovery amount, which is beneficial to improving the effectiveness of increasing cell capacity by releasing pre-stored lithium. In addition, when the mass percentage of pre-stored lithium in the maximum extractable lithium ions of the positive electrode active material is greater than the capacity recovery amount, since the cell capacity is also limited by the loss rate of the negative electrode active material and the loss rate of the positive electrode active material, further increasing the mass percentage of pre-stored lithium in the maximum extractable lithium ions of the positive electrode active material cannot improve the cell capacity by supplementing active lithium. This application embodiment controls the mass percentage of pre-stored lithium in the maximum extractable lithium ions of the positive electrode active material to be less than or equal to the capacity recovery amount, which is beneficial to reducing the waste of active lithium resources in the positive electrode active material and improving the utilization rate of pre-stored lithium.

[0106] In step B122, the electronic device can obtain only the relationship between the charging cutoff voltage of the calibrated cell and the delithiation ratio of the pre-stored lithium based on the pre-stored lithium amount, as the first mapping relationship. This helps to reduce the resource consumption of the electronic device in the process of obtaining the first mapping relationship and improve the efficiency of the electronic device in obtaining the first mapping relationship.

[0107] It should be noted that the method for determining the cell charging voltage involved in the above embodiments may include at least one of Embodiments 1 to 8. For example, Embodiment 1 can be implemented as an independent embodiment, Embodiment 1+2 can be implemented as an independent embodiment, Embodiment 1+3 can be implemented as an independent embodiment, Embodiment 1+2+3 can be implemented as an independent embodiment, Embodiment 1+4 can be implemented as an independent embodiment, Embodiment 1+2+4 can be implemented as an independent embodiment, Embodiment 1+3+4 can be implemented as an independent embodiment, Embodiment 1+2+3+4 can be implemented as an independent embodiment, Embodiment 1+5 can be implemented as an independent embodiment, Embodiment 1+2+5 can be implemented as an independent embodiment, Embodiment 1+3+5 can be implemented as an independent embodiment, Embodiment 1+4+5 can be implemented as an independent embodiment, and Embodiment 1+2+3+5 can be implemented as an independent embodiment. Examples can be used to implement this, such as Examples 1+2+4+5, Examples 1+3+4+5, Examples 1+2+3+4+5, Examples 1+2+3+4+5+6, Examples 1+2+3+4+5+7, Examples 1+2+3+4+5+8, Examples 1+2+3+4+5+6+8, Examples 1+2+3+4+5+7+8, Examples 1+2+3+4+5+6+7+8, etc., but are not limited to these examples, and will not be listed in detail here.

[0108] In one optional embodiment of this application, the method for determining the cell charging voltage provided in this application embodiment may further include, when the number of types of positive electrode active materials is equal to 1: Step C11: Obtain the upper limit voltage of the positive electrode active material in the target cell.

[0109] Step C12: Determine any voltage value lower than the upper limit voltage as the initial charging voltage of the target cell.

[0110] Specifically, when the target cell is charged to the initial charging voltage, the portion of active lithium that has not been extracted from the positive electrode active material of the target cell is pre-stored lithium. During the process of charging the target cell from the initial charging voltage to the upper limit voltage, the total amount of active lithium extracted from the positive electrode active material is equal to the total amount of pre-stored lithium in the positive electrode active material of the target cell.

[0111] As an example, refer to Figure 4 This illustration shows a schematic diagram of the charging curve of a target battery cell containing lithium iron phosphate (LFP) positive electrode active material, as provided in an embodiment of this application; Figure 4 As shown, the upper limit voltage of the lithium iron phosphate positive electrode active material is 3.8V. The electronic device can determine 3.5V as the initial charging voltage of the target cell through step C12. When the target cell is charged to the initial charging voltage of 3.5V, the active lithium that has not been extracted from the positive electrode active material of the target cell is the pre-stored lithium.

[0112] SOC (State of Charge) refers to the state of charge of a target battery cell, which is used to characterize the percentage of the target battery cell's current remaining capacity relative to its rated capacity. It is a parameter for measuring the remaining capacity of a target battery cell.

[0113] In one optional embodiment of this application, the method for determining the cell charging voltage provided in this application may further include, when the number of types of positive electrode active materials is greater than or equal to two: Step C21: Obtain the upper limit voltage of each positive electrode active material in the target cell.

[0114] Step C22: Sort the upper limit voltages of the positive electrode active materials according to their magnitude.

[0115] Step C23: Determine the minimum value of the upper limit voltage as the initial charging voltage of the target cell.

[0116] Specifically, when the target cell is charged to the initial charging voltage, the portion of active lithium that has not been extracted from the positive electrode active material of the target cell is pre-stored lithium. During the process of charging the target cell from the initial charging voltage to the maximum value of the upper limit voltage, the total amount of active lithium extracted from the positive electrode active material is equal to the total amount of pre-stored lithium in the positive electrode active material of the target cell.

[0117] As an example, refer to Figure 5 This illustration shows a comparative charging curve diagram of a target battery cell containing lithium iron phosphate cathode active material and a target battery cell containing lithium nickel cobalt manganese oxide (NCM) ternary cathode active material, according to embodiments of this application. Figure 5 As shown, when the positive electrode active material includes both lithium iron phosphate positive electrode active material and lithium nickel cobalt manganese oxide ternary positive electrode active material, the upper limit voltage of the lithium iron phosphate positive electrode active material is 3.8V, and the upper limit voltage of the lithium nickel cobalt manganese oxide ternary positive electrode active material is 4.4V. The electronic device can execute step C23 to determine the upper limit voltage of the lithium iron phosphate positive electrode active material 3.8V as the initial charging voltage of the target cell. When the target cell is charged to the initial charging voltage of 3.8V, the active lithium that has not been extracted from the positive electrode active material of the target cell is the pre-stored lithium.

[0118] Reference Figure 6 The flowchart illustrates the steps of a method for determining the charging voltage of a battery cell according to an embodiment of this application. Figure 2The method may specifically include: Step S201: Select the cell system.

[0119] Specifically, the cell system selected in step S201 can be any type of cell system in the field of cell technology; after selecting the cell system, a calibration cell with that cell system can be prepared.

[0120] Step S202: The electronic device obtains the loss rate k1 of the negative electrode active material, the loss rate k2 of the positive electrode active material, and the loss rate k3 of the active lithium under different cell capacities of the calibrated cell.

[0121] Step S203: The electronic device determines whether k1, k2 and k3 of the calibrated cell satisfy k3 > k1 and k3 > k2 under each cell capacity.

[0122] Specifically, when k3 > k1 and k3 > k2, k1, k2 and k3 satisfy k3 > k1 and k3 > k2, indicating that the cell system of the calibrated cell is dominated by active lithium loss at the cell capacity, and the method of restoring capacity by replenishing active lithium is effective. In this scenario, the electronic device can continue to perform the operation corresponding to step S204.

[0123] When k3≤k1 and / or k3≤k2, k1, k2 and k3 do not satisfy k3>k1 and k3>k2. The cell system of the calibrated cell is not dominated by active lithium loss at the cell capacity. The effect of restoring capacity by supplementing active lithium is limited. In this scenario, the electronic device can execute step S202 again to obtain the negative electrode active material loss rate k1, positive electrode active material loss rate k2 and active lithium loss rate k3 of the calibrated cell at different cell capacities.

[0124] Step S204: The electronic device determines the capacity recovery amount that the calibrated cell system can achieve by releasing the pre-stored lithium in the positive electrode active material based on k1, k2 and k3.

[0125] The specific implementation of step S204 can be found in the detailed description of steps B1111 to B1113, and will not be repeated here.

[0126] Step S205: The electronic device obtains the relationship between the charging cutoff voltage of the calibrated cell and the delithiation ratio of the positive electrode active material based on the capacity recovery amount, and obtains the first mapping relationship.

[0127] The specific implementation of step S205 can be found in the detailed description of step B12, and will not be repeated here.

[0128] Step S206: The electronic device obtains the capacity decay rate corresponding to the target cell.

[0129] Step S207: The electronic device designs the target battery cell.

[0130] The target cell has the same cell system as the calibration cell, and the positive electrode active material of the target cell includes pre-stored lithium.

[0131] Specifically, firstly, the electronic device determines the pre-stored lithium from the positive electrode active material of the target cell according to the capacity decay rate obtained in step S206 and the capacity recovery amount determined in step S204, using the same or similar method as step A11; then, the electronic device determines the initial charging voltage of the target cell using the same or similar method as step A12.

[0132] Step S208: The electronic device obtains the actual capacity of the target battery cell.

[0133] Step S209: The electronic device determines the amount of lithium pre-stored in the positive electrode active material of the target battery cell to be released based on the actual capacity of the target battery cell.

[0134] The specific implementation of step S209 can be found in the detailed description of step S101, and will not be repeated here.

[0135] Step S210: The electronic device determines the charging voltage of the target cell based on the amount of pre-stored lithium released and the first mapping relationship.

[0136] Specifically, the detailed implementation of step S210 can be found in the detailed description of step S102, and will not be repeated here.

[0137] In summary, the method for determining the battery cell charging voltage provided in this application embodiment determines the amount of pre-stored lithium released from the positive electrode active material of the target battery cell based on the actual capacity of the target battery cell, and determines the charging voltage of the target battery cell based on the amount of pre-stored lithium released and the first mapping relationship. When the target battery cell needs to be charged in the future, it can be charged based on the charging voltage of the target battery cell determined in this application embodiment. By releasing the pre-stored lithium in the positive electrode active material of the target battery cell, the lithium ion loss in the target battery cell is replenished, thereby increasing the actual capacity of the target battery cell to the target capacity. The replenishment of active lithium in the target battery cell can be achieved without adding lithium replenishing agent to the positive electrode of the target battery cell, which is beneficial to improving the stability of the target battery cell during use. Moreover, by controlling the amount of pre-stored lithium released, this application embodiment can control the degree of capacity recovery of the target battery cell, so that the capacity of the target battery cell decays at a lower decay rate or does not decay at all within a certain operating cycle, which is beneficial to slowing down the decay rate of the target battery cell's service life and extending the service life of the target battery cell.

[0138] Device Examples Reference Figure 7 The diagram illustrates a logic block diagram of a device for determining the charging voltage of a battery cell according to an embodiment of this application. The device includes: The first determining module 701 is used to determine the amount of lithium pre-stored in the positive electrode active material to be released based on the actual capacity of the target battery cell. The second determining module 702 is used to determine the charging voltage of the target battery cell based on the release amount and the first mapping relationship; The first mapping relationship includes the relationship between the charging cut-off voltage of the battery cell and the delithiation ratio of the positive electrode active material.

[0139] Optionally, the first determining module includes: The first acquisition submodule is used to acquire the delithiation ratio required to increase the actual capacity to the target capacity when the actual capacity is less than or equal to the target threshold, or when the actual capacity is less than the target capacity, wherein the target threshold is less than the target capacity. The first determining submodule is used to determine the delithiation ratio as the amount of lithium released from the pre-stored lithium in the positive electrode active material.

[0140] Optionally, the second determining module includes: The second determining submodule is used to determine the charging cutoff voltage corresponding to the release amount from the first mapping relationship; The third determining submodule is used to determine the charging cutoff voltage corresponding to the release amount as the charging voltage of the target battery cell.

[0141] Optionally, the device further includes: The third determining module is used to determine the pre-stored lithium from the positive electrode active material of the target battery cell based on the capacity decay rate of the target battery cell. The fourth determining module is used to determine the initial charging voltage of the target battery cell based on the pre-stored lithium and the first mapping relationship.

[0142] Optionally, the device further includes: The fifth determining module is used to determine the capacity recovery amount that the calibrated battery cell system can achieve by supplementing active lithium, based on the loss rate of negative electrode active material, loss rate of positive electrode active material, and loss rate of active lithium at different battery cell capacities; the battery cell system of the calibrated battery cell is the same as the battery cell system of the target battery cell. The acquisition module is used to obtain the relationship between the charging cut-off voltage of the calibrated cell and the delithiation ratio of the positive electrode active material based on the capacity recovery amount, and obtain the first mapping relationship.

[0143] Optionally, the fifth determining module includes: The fourth determining submodule is used to determine the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium when the active lithium loss rate is greater than the negative electrode active material loss rate and the active lithium loss rate is greater than the positive electrode active material loss rate, based on the negative electrode active material loss rate, the positive electrode active material loss rate and the active lithium loss rate.

[0144] Optionally, the fourth determining submodule includes: The first calculation unit is used to calculate a first difference between the active lithium loss rate and the negative electrode active material loss rate when the active lithium loss rate is greater than the negative electrode active material loss rate and the active lithium loss rate is greater than the positive electrode active material loss rate. The second calculation unit is used to calculate a second difference between the active lithium loss rate and the positive electrode active material loss rate; A determining unit is used to determine the minimum value between the first difference and the second difference as the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium.

[0145] Optionally, the acquisition module includes: The fifth determining submodule is used to determine the pre-stored lithium corresponding to the positive electrode active material in the cell system of the calibrated cell based on the capacity recovery amount; The acquisition submodule is used to obtain the relationship between the charging cut-off voltage of the calibration cell and the delithiation ratio of the positive electrode active material based on the pre-stored lithium corresponding to the positive electrode active material in the cell system of the calibration cell, and obtain the first mapping relationship.

[0146] As the device embodiment is basically similar to the method embodiment, the description is relatively simple, and relevant parts can be found in the description of the method embodiment.

[0147] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0148] This application also provides an electronic device, which includes a memory and a processor. The memory stores an executable program or instructions, and the processor runs the program or instructions to implement the method for determining the battery cell charging voltage as described above.

[0149] This application also provides a vehicle, which includes a battery cell and an electronic device as described above, wherein the electronic device determines the charging voltage of the battery cell using the battery cell charging voltage determination method described above.

[0150] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0151] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, or computer program products. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of this application can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0152] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0153] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0154] The above provides a detailed description of the method, apparatus, electronic device, and vehicle for determining the charging voltage of a battery cell. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, those skilled in the art will recognize that there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for determining the charging voltage of a battery cell, characterized in that, The method includes: The amount of lithium released from the pre-stored lithium in the positive electrode active material is determined based on the actual capacity of the target battery cell. Based on the release amount and the first mapping relationship, the charging voltage of the target battery cell is determined; The first mapping relationship includes the relationship between the charging cut-off voltage of the battery cell and the delithiation ratio of the positive electrode active material.

2. The method according to claim 1, characterized in that, The step of determining the release amount of pre-stored lithium in the positive electrode active material based on the actual capacity of the target battery cell includes: If the actual capacity is less than or equal to the target threshold, or if the actual capacity is less than the target capacity, obtain the delithiation ratio required to increase the actual capacity to the target capacity, where the target threshold is less than the target capacity; The delithiation ratio is defined as the amount of lithium released from the pre-stored lithium in the positive electrode active material.

3. The method according to claim 1 or 2, characterized in that, Determining the charging voltage of the target battery cell based on the release amount and the first mapping relationship includes: Determine the charging cutoff voltage corresponding to the release amount from the first mapping relationship; The charging cutoff voltage corresponding to the release amount is determined as the charging voltage of the target battery cell.

4. The method according to any one of claims 1 to 3, characterized in that, The method further includes: Based on the capacity decay rate of the target battery cell, pre-stored lithium is determined from the positive electrode active material of the target battery cell; The initial charging voltage of the target battery cell is determined based on the pre-stored lithium and the first mapping relationship.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes: Based on the loss rates of negative electrode active materials, positive electrode active materials, and active lithium at different cell capacities of the calibrated cell, the capacity recovery achievable by supplementing active lithium in the cell system of the calibrated cell is determined; the cell system of the calibrated cell is the same as that of the target cell. Based on the capacity recovery amount, the relationship between the charging cutoff voltage of the calibrated cell and the delithiation ratio of the positive electrode active material is obtained, thus obtaining the first mapping relationship.

6. The method according to claim 5, characterized in that, The determination of the capacity recovery achievable by supplementing active lithium in the cell system of the calibrated cell, based on the loss rates of negative electrode active materials, positive electrode active materials, and active lithium at different cell capacities, includes: When the active lithium loss rate is greater than the negative electrode active material loss rate, and the active lithium loss rate is greater than the positive electrode active material loss rate, the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium is determined based on the negative electrode active material loss rate, the positive electrode active material loss rate, and the active lithium loss rate.

7. The method according to claim 6, characterized in that, When the active lithium loss rate is greater than the negative electrode active material loss rate, and the active lithium loss rate is greater than the positive electrode active material loss rate, determining the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium, based on the negative electrode active material loss rate, the positive electrode active material loss rate, and the active lithium loss rate, includes: If the active lithium loss rate is greater than the negative electrode active material loss rate, and the active lithium loss rate is greater than the positive electrode active material loss rate, calculate the first difference between the active lithium loss rate and the negative electrode active material loss rate. Calculate the second difference between the active lithium loss rate and the positive electrode active material loss rate; The minimum value between the first difference and the second difference is determined as the capacity recovery amount that the calibrated cell system can achieve by supplementing active lithium.

8. The method according to any one of claims 5 to 7, characterized in that, The step of obtaining the relationship between the charging cutoff voltage of the calibrated cell and the lithium removal ratio of the positive electrode active material based on the capacity recovery amount, to obtain the first mapping relationship, includes: Based on the capacity recovery amount, determine the pre-stored lithium corresponding to the positive electrode active material in the cell system of the calibrated cell; Based on the pre-stored lithium corresponding to the positive electrode active material in the calibrated cell system, the relationship between the charging cut-off voltage of the calibrated cell and the lithium removal ratio of the positive electrode active material is obtained, thus obtaining the first mapping relationship.

9. A device for determining the charging voltage of a battery cell, characterized in that, The device includes: The first determining module is used to determine the amount of lithium pre-stored in the positive electrode active material to be released based on the actual capacity of the target battery cell. The second determining module is used to determine the charging voltage of the target battery cell based on the release amount and the first mapping relationship; The first mapping relationship includes the relationship between the charging cut-off voltage of the battery cell and the delithiation ratio of the positive electrode active material.

10. An electronic device, characterized in that, The device includes a memory and a processor, wherein the memory stores an executable program or instructions, and the processor executes the program or instructions to implement the method for determining the cell charging voltage as described in any one of claims 1 to 8.

11. A vehicle, characterized in that, The device includes a battery cell and an electronic device as described in claim 10, wherein the electronic device determines the charging voltage of the battery cell using a method for determining the charging voltage of the battery cell as described in any one of claims 1 to 8.

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