Method, device and equipment for evaluating continuous charging performance of lithium-ion batteries

Abstract

This application discloses a method, apparatus, and device for evaluating the continuous charging performance of lithium-ion batteries, relating to the field of power battery technology. The method includes: determining the maximum charging current of the battery cell at different characteristic states of charge (SFCs) at various target characteristic temperatures based on a negative electrode potential safety threshold line and linear curves of the negative electrode potential versus dynamic charging current at different SFCs within each target characteristic temperature range; determining the charging performance data of the battery cell based on the maximum charging current of the battery cell at different SFCs within each temperature range; and formulating a corresponding continuous charging MAP based on the battery cell's charging performance data and a dual safety margin dynamic adjustment strategy, thereby evaluating and verifying the continuous charging performance of the lithium-ion battery at the current temperature. Through the above method, the maximum charging current of the battery cell at different temperatures and SFCs is accurately determined, and a continuous charging MAP is formulated.

Description

Technical Field

[0001] This application relates to the field of power battery technology, and in particular to methods, apparatus and equipment for evaluating the continuous charging performance of lithium-ion batteries. Background Technology

[0002] Lithium plating in lithium-ion batteries refers to the phenomenon where, during battery charging, certain abnormal conditions prevent lithium ions that have been extracted from the positive electrode from embedding in the negative electrode, resulting in the deposition of a layer of metallic lithium on the negative electrode surface. Lithium-ion batteries exhibit significant polarization during high-rate charging. As the charging current increases, the negative electrode potential gradually decreases. When the negative electrode potential falls below the lithium plating potential, there is a risk of lithium plating, which is an irreversible process. Especially at low temperatures, lithium dendrites can easily form, piercing the separator and causing a short circuit, leading to battery life degradation and safety risks. Therefore, evaluating the continuous charging performance of lithium-ion batteries requires ensuring the negative electrode potential is above the lithium plating potential, determining the maximum continuous charging current, and guaranteeing safety throughout the cell's lifespan, thereby achieving safe and efficient battery operation.

[0003] In the existing technology, there are few studies on methods for rapidly evaluating the continuous charging current of lithium-ion batteries, and the evaluation of the continuous charging performance of lithium-ion batteries has problems such as multiple test conditions, long test cycles, and high test resource and manpower costs.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main objective of this application is to provide a method, apparatus, and device for evaluating the continuous charging performance of lithium-ion batteries, aiming to solve the technical problems that the traditional methods for evaluating the continuous charging performance of lithium-ion batteries are relatively complex, costly, and difficult to achieve quickly and accurately.

[0006] To achieve the above objectives, this application provides a method for evaluating the continuous charging performance of a lithium-ion battery, the method comprising:

[0007] The operating temperature range of the cell in the lithium-ion battery is divided into multiple temperature ranges. Multiple characteristic temperatures are set within the temperature ranges according to a preset temperature gradient, and multiple characteristic states of charge are set within the state of charge range according to a preset load gradient. The temperature ranges include at least a low temperature range, a normal temperature range, and a high temperature range.

[0008] Select the target characteristic temperature within the temperature range, and determine the maximum charging current corresponding to the different characteristic states of charge of the cell at each target characteristic temperature based on the negative electrode potential safety threshold line and the linear curve of the negative electrode potential and dynamic charging current corresponding to the different characteristic states of charge of the cell at each target characteristic temperature.

[0009] Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in each temperature range, the charging performance data of each temperature range is determined. Different strategies are used to determine the charging performance data for different temperature ranges.

[0010] Based on the charging performance data of each temperature range, the charging performance data of the battery cell within the operating temperature range is determined.

[0011] Based on the charging performance data of the battery cell within its operating temperature range, and based on a dual safety margin dynamic adjustment strategy, a corresponding continuous charging MAP is formulated to evaluate and verify the continuous charging performance of the lithium-ion battery at the current temperature.

[0012] In one embodiment, the step of determining the maximum charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures, based on the negative electrode potential safety threshold line and the linear curves of negative electrode potential versus dynamic charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures, includes:

[0013] Obtain linear curves of negative electrode potential versus dynamic charging current of the battery cell at different characteristic states of charge at various target characteristic temperatures;

[0014] Determine the intersection points of the negative electrode potential safety threshold line and each linear curve;

[0015] The charging current at the intersection of different characteristic states of charge of the battery cell at various target characteristic temperatures is taken as the maximum charging current.

[0016] In one embodiment, the step of obtaining the linear curves of the negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures includes:

[0017] Discharge the battery cell to the first state of charge according to the preset discharge current;

[0018] Based on the dynamic current testing strategy, the battery cell is charged at different target characteristic temperatures to charge the battery cell to the second state of charge. The dynamic current testing strategy uses multiple preset charging currents.

[0019] Based on the three-electrode strategy, the negative electrode potential data and battery voltage data of the cell are recorded during the charging test, and the variation curves of the negative electrode potential and state of charge of the cell at various target characteristic temperatures under different charging currents are generated.

[0020] Based on the variation curves of the negative electrode potential and state of charge of the battery cell at various target characteristic temperatures under different charging currents, the linear curves of the negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures are determined.

[0021] In one embodiment, the step of determining the linear curve of the negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures based on the change curves of the negative electrode potential and state of charge of the battery cell at different target characteristic temperatures includes:

[0022] Based on the variation curves of negative electrode potential and state of charge of the battery cell at various target characteristic temperatures under different charging currents, the charging current data and negative electrode potential data corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures are determined, and effective linear data are selected.

[0023] By fitting the effective linear data corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures, linear curves of negative electrode potential and charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures are obtained.

[0024] In one embodiment, the target characteristic temperature in the normal temperature range is all characteristic temperatures in the normal temperature range, the target characteristic temperature in the low temperature range is a preset number of characteristic temperatures selected in the low temperature range, and the target characteristic temperature in the high temperature range is all characteristic temperatures in the high temperature range. The step of determining the charging performance data for each temperature range based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperatures in each temperature range includes:

[0025] Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the room temperature range, the charging performance data in the room temperature range is determined.

[0026] Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at target characteristic temperatures in the normal temperature and low temperature regions, a calculation model for the maximum charging current in the low temperature region is fitted, and the charging performance data in the low temperature region is determined based on the calculation model for the maximum charging current.

[0027] Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region, the maximum safe charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region is determined, and charging performance data of the high-temperature region is generated based on the maximum safe charging current.

[0028] In one embodiment, the step of determining the maximum safe charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region, based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region, includes:

[0029] Obtain the maximum charging current for temperature rise corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region;

[0030] Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the normal temperature range, the upper limit of the current in the normal temperature range corresponding to different characteristic states of charge is determined, and based on the upper limit of the current in the normal temperature range corresponding to different characteristic states of charge, the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high temperature range is adjusted.

[0031] Based on the principle of safety first, the minimum current is determined from the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature zone and the maximum charging current with temperature rise, and is taken as the maximum safe charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature zone.

[0032] In one embodiment, the step of obtaining the maximum charging current for temperature rise corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region includes:

[0033] Obtain the corresponding relationship between cell specific heat capacity, cell mass, temperature difference, cell dynamic internal resistance and maximum charging current at temperature rise;

[0034] Based on the specific heat capacity of the battery cell, the mass of the battery cell, the dynamic internal resistance of the battery cell, the temperature difference between the target characteristic temperature and the upper limit of the operating temperature in the high-temperature zone, and the corresponding relationship, the maximum charging current corresponding to the temperature rise of the battery cell at different characteristic states of charge under the target characteristic temperature in the high-temperature zone is determined.

[0035] In one embodiment, the steps of evaluating and verifying the continuous charging performance of the lithium-ion battery at the current temperature, based on the charging performance data of the battery cell within the operating temperature range and a dual safety margin dynamic adjustment strategy, include:

[0036] Get the current state of charge and the current temperature;

[0037] When the current state of charge is less than the preset boundary state of charge, the target temperature is determined based on the current temperature and the temperature safety margin. The temperature safety margin is determined based on the temperature safety factor and the preset temperature gradient.

[0038] The target state of charge is determined based on the current state of charge and the state of charge safety margin. The state of charge safety margin is determined based on the state of charge safety factor and the preset state of charge level.

[0039] Based on the target temperature and target state of charge, the corresponding target maximum charging current is determined from the charging performance data;

[0040] Based on the target maximum charging current, generate a continuous charging MAP at the current temperature.

[0041] Furthermore, to achieve the above objectives, this application also proposes an evaluation device for the continuous charging performance of lithium-ion batteries, the evaluation device comprising:

[0042] The parameter division module is used to divide the working temperature range of the cell in the lithium-ion battery into multiple temperature ranges, set multiple characteristic temperatures within the temperature range according to a preset temperature gradient, and set multiple characteristic states of charge within the state of charge range according to a preset load gradient. The temperature range includes at least a low temperature range, a normal temperature range, and a high temperature range.

[0043] The data calculation module is used to select the target characteristic temperature from the temperature range, and based on the negative electrode potential safety threshold line and the linear curve of the negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the cell at each target characteristic temperature, determine the maximum charging current corresponding to different characteristic states of charge of the cell at each target characteristic temperature.

[0044] The data calculation module is also used to determine the charging performance data of each temperature range based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in each temperature range. Different strategies are used to determine the charging performance data for different temperature ranges.

[0045] The data calculation module is also used to determine the charging performance data of the battery cell within the operating temperature range based on the charging performance data of each temperature range.

[0046] The performance evaluation module is used to evaluate and verify the continuous charging performance of lithium-ion batteries at the current temperature by formulating a corresponding continuous charging MAP based on the charging performance data of the battery cell within the operating temperature range and a dual safety margin dynamic adjustment strategy.

[0047] In addition, to achieve the above objectives, this application also proposes an evaluation device for the continuous charging performance of lithium-ion batteries. The evaluation device for the continuous charging performance of lithium-ion batteries includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. The computer program is configured to implement the steps of the evaluation method for the continuous charging performance of lithium-ion batteries as described above.

[0048] In addition, to achieve the above objectives, the present invention also proposes a storage medium, which is a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps of the method for evaluating the continuous charging performance of a lithium-ion battery as described above.

[0049] In addition, to achieve the above objectives, this application also provides a computer program product, which includes a computer program that, when executed by a processor, implements the steps of the method for evaluating the continuous charging performance of a lithium-ion battery as described above.

[0050] This application provides a method for evaluating the continuous charging performance of a lithium-ion battery. The method divides the operating temperature range of the battery cell into multiple temperature zones. Multiple characteristic temperatures are set within each temperature zone according to a preset temperature gradient, and multiple characteristic states of charge (SOCs) are set within each SOC range according to a preset load gradient. The temperature zones include at least a low-temperature zone, a normal-temperature zone, and a high-temperature zone. Target characteristic temperatures are selected from each temperature zone. Based on the negative electrode potential safety threshold line and the linear curves of the negative electrode potential and dynamic charging current corresponding to different SOCs at each target characteristic temperature, the maximum charging current corresponding to different SOCs at each target characteristic temperature is determined. Based on the maximum charging current corresponding to different SOCs at each target characteristic temperature, charging performance data for each temperature zone is determined. Different strategies are used to determine the charging performance data for different temperature zones. Based on the charging performance data for each temperature zone, the charging performance data of the battery cell within the operating temperature range is determined. Based on the charging performance data of the battery cell within the operating temperature range and based on a dual safety margin dynamic adjustment strategy, a corresponding continuous charging MAP is formulated to evaluate and verify the continuous charging performance of the lithium-ion battery at the current temperature. This application combines the dynamic current method and the three-electrode method to obtain linear curves of negative electrode potential and dynamic charging current under different temperatures and states of charge. It also sets a safe threshold line for the negative electrode potential of lithium plating potential. By using the intersection of the linear curve and the safe threshold line, the maximum charging current of the cell under different temperatures and states of charge can be determined. This allows for a rapid and accurate assessment of the cell's maximum continuous charging capability. Furthermore, based on the cell's maximum continuous charging capability, a continuous charging strategy and charging MAP are formulated to ensure the safety of the cell throughout its entire life cycle. This enables the power battery to operate safely and efficiently, solving the technical problems that traditional methods for evaluating the continuous charging performance of lithium-ion batteries are complex, costly, and difficult to implement quickly and accurately. Attached Figure Description

[0051] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0052] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a flowchart illustrating an embodiment of the method for evaluating the continuous charging performance of lithium-ion batteries according to this application.

[0054] Figure 2 A schematic diagram of the negative electrode potential change curve for the evaluation method of the continuous charging performance of the lithium-ion battery provided in Embodiment 1 of this application.

[0055] Figure 3 A schematic diagram of linear curve fitting for the evaluation method of the continuous charging performance of lithium-ion batteries provided in Embodiment 1 of this application;

[0056] Figure 4 A schematic diagram of the maximum current fitting curve in the low-temperature region for the evaluation method of the continuous charging performance of the lithium-ion battery provided in Embodiment 1 of this application.

[0057] Figure 5 This is a flowchart illustrating Example 2 of the method for evaluating the continuous charging performance of lithium-ion batteries according to this application.

[0058] Figure 6 This is a schematic diagram of the module structure of the evaluation device for the continuous charging performance of a lithium-ion battery according to an embodiment of this application;

[0059] Figure 7 This is a schematic diagram of the hardware operating environment involved in the evaluation method for the continuous charging performance of lithium-ion batteries in the embodiments of this application.

[0060] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0061] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0062] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0063] It should be noted that the executing entity in this embodiment can be a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, or mobile phone, or an electronic device capable of performing the above functions, or an evaluation device for the continuous charging performance of lithium-ion batteries, etc. This embodiment does not specifically limit it. The following uses an evaluation device for the continuous charging performance of lithium-ion batteries as an example to describe this embodiment and the following embodiments.

[0064] This application provides a method for evaluating the continuous charging performance of lithium-ion batteries, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the method for evaluating the continuous charging performance of lithium-ion batteries according to this application.

[0065] In this embodiment, the method for evaluating the continuous charging performance of a lithium-ion battery includes steps S10 to S40:

[0066] Step S10: Divide the operating temperature range of the cell in the lithium-ion battery into multiple temperature ranges, set multiple characteristic temperatures within the temperature ranges according to a preset temperature gradient, and set multiple characteristic states of charge within the state of charge range according to a preset load gradient.

[0067] It should be noted that the operating temperature range of a battery cell usually refers to the temperature range within which the cell operates normally. This range can be set according to actual conditions and is not specifically limited. In this embodiment, the battery cell is a lithium-ion battery cell. This embodiment divides the operating temperature range of the battery cell into multiple temperature zones, which at least include a low-temperature zone, a normal-temperature zone, and a high-temperature zone. The characteristic temperature refers to the pre-set operating temperature of the battery cell, and the preset temperature gradient is the gradient between characteristic temperatures.

[0068] For example, if the operating temperature range is T min ~T max Given a preset temperature gradient of ΔT, the characteristic temperatures across the entire operating temperature range, arranged from low to high, can be represented as T1, T2, ..., T. n Then the low temperature zone can be set to T1~T l The normal temperature range is T l ~T m The high-temperature zone is T m ~T n , among which, T min T is the minimum operating temperature of the battery cell. max If T1 is the maximum operating temperature of the battery cell, then T1 = T min T n =T max T n =T1+ΔT·(n-1), l<m<n.

[0069] Additionally, it should be noted that the state of charge range refers to the range of the cell's state of charge (SOC), typically from 0% to 100%. Characteristic state of charge refers to a pre-set SOC value for the cell, and the preset load gradient is the gradient between characteristic states of charge.

[0070] For example, if the preset load gradient is ΔSOC, then SOC i = i·ΔSOC, where i is the i-th SOC value. It can be understood that SOC1 = 0 is the minimum SOC value of the battery cell, and SOC... j =100% is the maximum SOC value of the battery cell, 0≤i≤j.

[0071] Step S20: Select a target characteristic temperature from the temperature range, and determine the maximum charging current corresponding to different characteristic states of charge of the cell at each target characteristic temperature based on the negative electrode potential safety threshold line and the linear curve of negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the cell at each target characteristic temperature.

[0072] It should be noted that the target characteristic temperature is the temperature selected from the characteristic temperatures of each temperature range in this embodiment. Based on the target characteristic temperature of each temperature range, the maximum charging current is determined at different characteristic states of charge to evaluate the continuous charging capability of the battery cell at different temperatures.

[0073] In one feasible implementation, step S20 may include steps S201 to S202:

[0074] Step S201: Obtain the linear curves of negative electrode potential and dynamic charging current of the battery cell under different characteristic charging states at various target characteristic temperatures;

[0075] In one possible implementation, step S201 may include steps S2011 to S2014:

[0076] Step S2011: Discharge the battery cell to the first state of charge according to the preset discharge current;

[0077] It should be noted that the first state of charge refers to SOC=0, and the preset discharge current is the current used for discharge, such as 1C, without any specific limitation.

[0078] It is understandable that the battery cell discharges to the discharge cutoff voltage at the 1C standard, at which point SOC = 0 is satisfied.

[0079] Step S2012: Based on the dynamic current test strategy, the battery cell is charged at different target characteristic temperatures to charge the battery cell to the second state of charge. The dynamic current test strategy uses multiple preset charging currents.

[0080] It should be noted that the second state of charge refers to SOC = 100%. The dynamic current testing strategy refers to charging the battery cell using multiple preset charging currents.

[0081] Understandably, at the target characteristic temperature, charging tests are conducted on the battery cell using different charging currents until the cell is charged to the charging cutoff voltage, satisfying SOC = 100%. The charging currents can be denoted as I1, I2, ..., I... n .

[0082] Step S2013: Based on the three-electrode strategy, record the negative electrode potential data and battery voltage data of the cell during the charging test, and generate the change curves of the negative electrode potential and state of charge of the cell at each target characteristic temperature under different charging currents.

[0083] It should be noted that the three-electrode strategy, also known as the three-electrode method, measures electrode potential by introducing a reference electrode. The reference electrode serves as a comparison when measuring the positive and negative electrode potentials of the battery. This electrode does not participate in charging or discharging, has no polarization effect, and can accurately detect the potential value of the cell under test. By constructing a cell using the electrode under test and the reference electrode with a known precise electrode potential value, and measuring the electromotive force of the cell, the electrode potential of the electrode under test can be calculated. Therefore, this embodiment employs the three-electrode strategy to record the negative electrode potential of the cell during the charging test, while simultaneously recording the battery voltage.

[0084] During charging testing, the negative electrode potential and battery voltage of the battery cell change with the State of Charge (SOC). Based on the negative electrode potential corresponding to different characteristic states of charge at various target characteristic temperatures, curves showing the change of negative electrode potential with SOC at each target characteristic temperature can be obtained; that is, curves showing the change of negative electrode potential and state of charge at each target characteristic temperature. Similarly, based on the battery voltage corresponding to different characteristic states of charge at various target characteristic temperatures, curves showing the change of battery voltage and state of charge at each target characteristic temperature can be obtained; that is, curves showing the change of battery voltage and state of charge at each target characteristic temperature. For example, assuming the selected target characteristic temperature is T... k The characteristic states of charge are SOC1 = 0, SOC2, ..., SOC i ..., SOC j If i = 0, 1, ..., j, then we can obtain Figure 2 Similar curves showing the change in negative electrode potential versus state of charge and the change in battery voltage versus state of charge may exhibit different patterns depending on the battery system and battery type. Figure 2 This is just one example.

[0085] Since this embodiment uses different charging currents to charge the battery cells, each charging current has a corresponding change curve. In other words, if the dynamic current test strategy sets n charging currents, then at the target characteristic temperature, n curves showing the change of negative electrode potential and state of charge corresponding to different charging currents, as well as n curves showing the change of battery voltage and state of charge, can be obtained.

[0086] Step S2014: Based on the variation curves of the negative electrode potential and state of charge of the battery cell at each target characteristic temperature under different charging currents, determine the linear curves of the negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the battery cell at each target characteristic temperature.

[0087] In one feasible implementation, step S2014 may include: based on the change curves of the negative electrode potential and state of charge of the battery cell at each target characteristic temperature under different charging currents, determining the charging current data and negative electrode potential data corresponding to different characteristic states of charge of the battery cell at each target characteristic temperature, and filtering out effective linear data; fitting the effective linear data corresponding to different characteristic states of charge of the battery cell at each target characteristic temperature to obtain the linear curves of the negative electrode potential and charging current corresponding to different characteristic states of charge of the battery cell at each target characteristic temperature.

[0088] It should be noted that by following the curves showing the change in negative electrode potential and state of charge (SOC) of the battery cell at various target characteristic temperatures under different charging currents, the charging current and negative electrode potential corresponding to each characteristic SOC at the target characteristic temperature can be found. Since n curves showing the change in negative electrode potential and SOC corresponding to different charging currents can be obtained at the target characteristic temperature, n corresponding charging currents and negative electrode potentials can be obtained for the same characteristic SOC at the target characteristic temperature. For example, assume the selected target characteristic temperature is T. k The selected characteristic state of charge is SOC. i The target feature temperature is extracted as T. k And the state of charge is SOC i For data on different charging currents and negative electrode potentials, refer to... Figure 3 Intersection point A represents a data point. Since each target characteristic temperature has n curves showing the change in negative electrode potential and state of charge corresponding to different charging currents, the target characteristic temperature is T. k And the state of charge is SOC i There are n intersection points A in total, denoted as A1 to A2. n Point A1 = (I1, V) cath1 Point A2 = (I2, V) cath2 Point A n =(I n V cath,n Point A n The representative characteristic temperature is T k Characteristic state of charge is SOC i And the charging current is I n The negative electrode potential at that time.

[0089] Understandably, based on the charging current data and negative electrode potential data corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures, the negative electrode potential V is fitted. cath By using a linear curve of the charging current I, we obtain the linear curves of the negative electrode potential versus the charging current corresponding to different characteristic states of charge of the cell at various target characteristic temperatures. To ensure V... cathThe -I curve exhibits good linearity, but data selection is necessary to ensure the fitted curve maintains a linear relationship. Effective linear data refers to the selected data that meets the linearity requirements. For example, refer to... Figure 3 Point A3 does not satisfy the linear curve, so this data needs to be removed.

[0090] It should be understood that by fitting the effective linear data corresponding to each characteristic state of charge at the target characteristic temperature, a linear curve of the negative electrode potential versus charging current corresponding to each characteristic state of charge at the target characteristic temperature is obtained, thus yielding the linear curve of the negative electrode potential versus charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures. For example, the target characteristic temperature is T. k And the state of charge is SOC i At that time, it is possible to obtain the following by fitting: Figure 3 The linear curve of negative electrode potential versus charging current is shown.

[0091] Step S202: Determine the intersection points between the negative electrode potential safety threshold line and each linear curve, and take the charging current at the intersection points corresponding to different characteristic states of charge of the cell at each target characteristic temperature as the maximum charging current.

[0092] It should be noted that the negative electrode potential safety threshold line is the negative electrode potential safety threshold line at which lithium plating does not occur. During the charging process of a lithium battery, lithium ions are extracted from the positive electrode and inserted into the negative electrode. When certain abnormal conditions occur, lithium ions extracted from the positive electrode may fail to insert into the negative electrode, causing lithium ions to precipitate on the surface of the negative electrode, forming a gray substance. This phenomenon is called lithium plating. As the charging rate increases, the charging current increases, and the polarization increases. The lithium ion insertion reaction kinetics and diffusion rate in the solid phase of the negative electrode material decrease, and the negative electrode potential gradually decreases. At the same time, polarization also causes the lithium plating potential to shift negatively. Therefore, the standard lithium plating potential is considered to be ≤0V. When the negative electrode potential is lower than the lithium plating potential, lithium plating will occur, especially under low temperature conditions. Lithium dendrites are easily formed, which can puncture the separator and cause a short circuit, posing risks of battery life degradation and safety hazards.

[0093] To ensure sufficient redundancy in the negative electrode potential and guarantee safety throughout the cell's lifespan, a negative electrode potential higher than the standard lithium plating potential needs to be set as a safety potential, also known as the negative electrode potential safety threshold V. Saf This is used to determine the negative electrode potential safety threshold line, the negative electrode potential safety threshold V. Saf It can be set to 10mV. It can also be adjusted flexibly according to actual needs; there is no specific limitation on this. The negative electrode potential safety threshold line is a parallel line independent of the charging rate.

[0094] It is understood that this embodiment requires finding the intersection points between the negative electrode potential safety threshold line and each linear curve. The charging current at the intersection point is the maximum charging current corresponding to the target characteristic temperature and characteristic state of charge. For example, refer to... Figure 3 Point B represents the negative electrode potential safety threshold line and the linear curve (target characteristic temperature is T). k And the state of charge is SOC i The intersection point between points B and B, at which point B corresponds to the charging current I. MAx That is, the target characteristic temperature is T k And the state of charge is SOC i The maximum charging current at that time is denoted as When a certain point A n When the charging current is below the negative electrode potential safety threshold, it indicates that there is a risk of lithium plating on the negative electrode. Therefore, this point should be eliminated.

[0095] Therefore, the maximum charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures can be obtained, that is:

[0096]

[0097] Among them, T k Represents the k-th target characteristic temperature, SOC i Represents the i-th characteristic state of charge. This indicates the cell's performance at the target characteristic temperature T. k and characteristic state of charge (SOC) i The maximum charging current.

[0098] Step S30: Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in each temperature range, determine the charging performance data for each temperature range. Different strategies are used to determine the charging performance data for different temperature ranges.

[0099] It should be noted that the charging performance data for each temperature range, i.e., the continuous charging capability of the battery cell in each temperature range, is usually characterized by the maximum charging current corresponding to different temperatures and different states of charge (SOC). Since different influencing factors need to be considered in different temperature ranges, different strategies are required to further determine the charging performance data for different temperature ranges, based on the maximum charging current corresponding to different characteristic states of charge at the target characteristic temperature of each temperature range. The target characteristic temperature in the normal temperature range includes all characteristic temperatures within the normal temperature range; the target characteristic temperature in the low temperature range includes a preset number of characteristic temperatures selected within the low temperature range; and the target characteristic temperature in the high temperature range includes all characteristic temperatures within the high temperature range.

[0100] In one feasible implementation, step S30 may include steps S301 to S302:

[0101] Step S301: Determine the charging performance data for the normal temperature range based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the normal temperature range.

[0102] It should be noted that the target characteristic temperature selected in this embodiment is all characteristic temperatures within the normal temperature range. Therefore, the maximum charging current corresponding to different characteristic states of charge of the battery cell at the characteristic temperature of the normal temperature range is the same as the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature of the normal temperature range. The maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature of the normal temperature range can be used to characterize the continuous charging capability of the battery cell in the normal temperature range. After arranging them in a certain order, the charging performance data of the normal temperature range is generated. Assuming that the operating condition of all temperature values ​​in the normal temperature range is T... l ~T m The charging performance data in the normal temperature range can then be expressed as:

[0103]

[0104] In the formula, T k T represents l ~T m The k-th characteristic temperature, SOC i I represents the i-th characteristic state of charge. nor (T, SOC) represents the charging performance data at room temperature. This indicates the cell at its characteristic temperature T. k and characteristic state of charge (SOC) i The maximum charging current.

[0105] Step S302: Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperatures in the normal temperature range and the low temperature range, fit the maximum charging current calculation model in the low temperature range, and determine the charging performance data in the low temperature range based on the maximum charging current calculation model.

[0106] It should be noted that low temperatures have a significant impact on charging capability. Therefore, a preset number of characteristic temperatures are selected in the low-temperature region to evaluate charging capability, while the charging capability of other low-temperature regions is determined using a function fitting method. The preset number can be three, and the specific number and value are not specifically limited. For example, the low-temperature regions T1 to T2 are... l The target characteristic temperature selected is T. x T y T z , T1≤T x ≤T y ≤T z ≤T l T x = -20℃, Ty = -10℃, T z =0℃, at which point the battery cell's continuous charging capability at the target characteristic temperature can be described as:

[0107]

[0108]

[0109]

[0110] In the formula, T x T y T z SOC represents the target characteristic temperature of the low-temperature region. i Represents the i-th characteristic state of charge. This indicates the cell's performance at the target characteristic temperature T. x and characteristic state of charge (SOC) i The maximum charging current under the following conditions This indicates the cell's performance at the target characteristic temperature T. y and characteristic state of charge (SOC) i The maximum charging current under the following conditions This indicates the cell's performance at the target characteristic temperature T. z and characteristic state of charge (SOC) i The maximum charging current under the following conditions These represent the cell's performance at the target characteristic temperature T. x T y T z The ability to continuously charge.

[0111] Understandably, by utilizing the maximum charging current corresponding to different characteristic states of charge (SOCs) of the battery cell at various target characteristic temperatures in both the normal and low-temperature regions, and using temperature as the independent variable and the maximum charging current as the dependent variable, a polynomial function is used to fit the relationship between the maximum charging current and temperature. This yields a calculation model for the maximum charging current in the low-temperature region, which is then used to estimate the maximum charging current corresponding to different SOCs at other characteristic temperatures within the low-temperature region. This confirms the continuous charging capability in the low-temperature region. The polynomial function used for fitting can be binomial or difference form; there are no specific limitations on this. For example, if the polynomial function used for fitting is I = aT... 2 +bT+c, we can get the following: Figure 4 The fitted curve shown.

[0112] It should be understood that by using the maximum charging current calculation model in the low temperature region, the maximum charging current at other characteristic temperatures in the low temperature region can be obtained. Thus, the maximum charging current corresponding to different characteristic states of charge of the cell at all characteristic temperatures in the low temperature region can be used to characterize the cell's continuous charging capability in the low temperature region. After arranging them in a certain order, the charging performance data of the low temperature region can be generated.

[0113] Step S303: Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature zone, determine the maximum safe charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature zone, and generate charging performance data for the high-temperature zone based on the maximum safe charging current.

[0114] It should be noted that charging capacity (maximum charging current) is greatly affected by temperature, primarily in the following ways: Under high temperatures, the activity of the positive and negative electrode active materials increases, accelerating the rate of internal chemical reactions and exacerbating lithium-ion diffusion side reactions, leading to accelerated battery aging and shortened cycle life. High temperatures may also damage the stability of the SEI film, increasing electrolyte decomposition side reactions and positive electrode material structural degradation. Therefore, under the same state of charge, the charging current at high temperatures cannot exceed the maximum charging current at room temperature. Furthermore, under adiabatic conditions, the cell temperature rise is calculated, and the maximum charging current is checked and controlled to ensure safe battery operation at high temperatures. At this point, a safe maximum charging current can be further determined, i.e., the maximum safe charging current, to characterize the cell's continuous charging capacity in the high-temperature region. After arranging these values ​​in a certain order, charging performance data for the high-temperature region is generated. Assuming all temperature values ​​in the high-temperature region are under operating conditions T... m ~T n The charging performance data in the high-temperature region can then be expressed as:

[0115]

[0116] In the formula, T h T represents m ~T n The h-th characteristic temperature, SOC i I represents the i-th characteristic state of charge. hot (T, SOC) represents the charging performance data in the high-temperature region. This indicates the cell at its characteristic temperature T. h and characteristic state of charge (SOC) i The maximum safe charging current.

[0117] In one feasible implementation, step S303 may include steps S3031 to S3033:

[0118] Step S3031: Obtain the maximum charging current for temperature rise corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region.

[0119] It should be noted that the maximum charging current with temperature rise refers to the maximum charging current obtained based on the temperature rise.

[0120] In one feasible implementation, step S3031 may include: obtaining the correspondence between the cell specific heat capacity, cell mass, temperature difference, cell dynamic internal resistance and the maximum charging current with temperature rise; and determining the maximum charging current with temperature rise corresponding to different characteristic states of charge of the cell at the target characteristic temperature in the high temperature region based on the cell specific heat capacity, cell mass, cell dynamic internal resistance, temperature difference between the target characteristic temperature in the high temperature region and the upper limit of the operating temperature and the corresponding relationship.

[0121] It should be noted that the temperature difference refers to the difference between the target characteristic temperature and the upper limit of the operating temperature, where the upper limit of the operating temperature is the upper limit of the cell's operating temperature range. The relationship between cell specific heat capacity, cell mass, temperature difference, cell dynamic internal resistance, and the maximum charging current at temperature rise is the formula for calculating the maximum charging current at temperature rise. Under adiabatic conditions, satisfying I... 2 ·R·t=c p ·m·Δt, we can obtain: Therefore, the characteristic temperature is T h And the characteristic state of charge is SOC. i At that time, the maximum charging current based on temperature rise, i.e., the maximum charging current based on temperature rise, is:

[0122]

[0123] In the formula, This indicates the cell at its characteristic temperature T. h and characteristic state of charge (SOC) i Maximum charging current under temperature rise, c p Let m be the specific heat capacity of the battery cell, m be the mass of the battery cell, and Δt be the temperature difference, where Δt = T. limit -T h T limit T is the upper limit of the cell's operating temperature. h R is the target characteristic temperature, and R is the dynamic internal resistance of the cell. The dynamic internal resistance of the cell can be selected for 100s DC charging under normal operating conditions. The polarization effect is relatively stable after 100s, which also conforms to the internal resistance level of actual operation. It can be flexibly adjusted according to actual needs.

[0124] It is understandable that the maximum safe charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature zone cannot exceed the maximum charging current for temperature rise.

[0125] Step S3032: Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the room temperature range, determine the upper limit of the current in the room temperature range corresponding to different characteristic states of charge, and adjust the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high temperature range based on the upper limit of the current in the room temperature range corresponding to different characteristic states of charge.

[0126] It should be noted that the upper limit of the current in the normal temperature range is the maximum value of the maximum charging current in the normal temperature range corresponding to each characteristic state of charge. Since the charging current at high temperature under the same state of charge cannot be higher than the maximum charging current at normal temperature, the upper limit of the current in the normal temperature range corresponding to different characteristic states of charge needs to be used as the maximum charging current in the high temperature range to limit the maximum charging current in the high temperature range. This ensures that the maximum charging current of the battery cell corresponding to different characteristic states of charge at the target characteristic temperature in the normal temperature range will not exceed the upper limit of the current in the normal temperature range for the corresponding characteristic state of charge.

[0127] Step S3033: Based on the principle of safety priority, determine the minimum current from the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature zone and the maximum charging current for temperature rise, as the maximum safe charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature zone.

[0128] Understandably, following the principle of safety first, the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature zone cannot exceed the maximum charging current due to temperature rise. Therefore, it is necessary to select the minimum value among them as the corresponding maximum safe charging current, as shown below:

[0129]

[0130] In the formula, T h Indicates the high temperature region T m ~T n The h-th characteristic temperature, SOC i Represents the i-th characteristic state of charge. This indicates the cell at its characteristic temperature T. h and characteristic state of charge (SOC) i The maximum safe charging current under these conditions This indicates the cell at its characteristic temperature T. h and characteristic state of charge (SOC) i Maximum charging current under temperature rise, This indicates the cell at its characteristic temperature T. h and characteristic state of charge (SOC) i The maximum charging current.

[0131] Step S40: Based on the charging performance data for each temperature range, determine the charging performance data of the battery cell within the operating temperature range.

[0132] It should be noted that by integrating the charging performance data from various temperature ranges, the charging performance data of the battery cell within its operating temperature range can be obtained.

[0133]

[0134] In the formula, T1~T n Indicates the characteristic temperature, SOC i Let I(T, SOC) represent the i-th characteristic state of charge, and let I(T, SOC) represent the charging performance data within the operating temperature range. This indicates the battery cell's ability to continuously charge under different characteristic temperatures and different characteristic states of charge.

[0135] Step S50: Based on the charging performance data of the battery cell within the operating temperature range and based on the dual safety margin dynamic adjustment strategy, formulate the corresponding continuous charging MAP to evaluate and verify the continuous charging performance of the lithium-ion battery at the current temperature.

[0136] It should be noted that the continuous charging capability of the aforementioned battery cells is used as a benchmark to formulate and evaluate the continuous charging MAP of the cells. To ensure the safe and efficient operation of the battery cells, the principle of the continuous charging MAP system is to determine the maximum charging current according to a dual safety margin dynamic adjustment strategy. That is, to set a temperature safety margin and a state of charge safety margin, and when the state of charge is less than the preset boundary, to determine the maximum charging current according to the preset temperature safety margin and state of charge safety margin.

[0137] Based on the cell's operating temperature range, a verification characteristic temperature is selected. Based on this characteristic temperature, and according to a preset temperature safety margin, a verification target temperature is determined. The temperature safety margin is calculated by increasing εΔT from the verification characteristic temperature, and the resulting temperature is selected as the verification target temperature. Here, ε is the temperature safety factor, typically set to 1 or 2, and ΔT is the preset temperature gradient. Therefore, the temperature safety margin is determined by the temperature safety factor and the preset temperature gradient; it is the product of these two factors. The verification characteristic temperature is increased according to the temperature safety margin, and the resulting temperature is the verification target temperature.

[0138] Based on the target temperature, charge-discharge cycle tests were conducted (charging involved selecting the corresponding charging current for the corresponding charging MAP). After the cycle test, the cell was fully charged (SOC = 100%) under appropriate conditions, and then disassembled to check for lithium plating at the interface, thus verifying the reliability of the continuous charging MAP. If lithium plating was found, the current needed to be readjusted for further evaluation and verification.

[0139] For example, the verification characteristic temperature can be 20℃, 0℃, -10℃, or -20℃, without specific limitation. If the preset temperature gradient ΔT = 5℃, the temperature safety factor ε = 1, the state of charge safety factor β = 1, and the calculated temperature safety margin εΔT = 5℃, then the verification characteristic temperature is increased by 5℃, and the increased temperature value is selected as the verification target temperature. The corresponding verification target temperatures are 25℃, 5℃, -5℃, and -15℃.

[0140] This embodiment provides a method for evaluating the continuous charging performance of lithium-ion batteries. Under different temperatures and states of charge, the method combines dynamic current method and three-electrode method to obtain linear curves of negative electrode potential and dynamic charging current, and sets a safe threshold line for lithium deposition potential on the negative electrode. By using the intersection of the linear curve and the safe threshold line, the maximum charging current of the cell under different temperatures and states of charge is determined, thus quickly and accurately evaluating the maximum continuous charging capability of the cell. At the same time, based on the maximum continuous charging capability of the cell, a continuous charging strategy and charging MAP are formulated to ensure the safety of the cell throughout its entire life cycle and achieve safe and efficient operation of the power battery.

[0141] Based on the first embodiment of this application, in the second embodiment of this application, the content that is the same as or similar to that in the first embodiment described above can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 5 Step S50 may include steps S501 to S504:

[0142] Step S501: Obtain the current state of charge and the current temperature;

[0143] It should be noted that the current state of charge is the current SOC value of the cell, and the current temperature is the current temperature of the cell.

[0144] Step S502: When the current state of charge is less than the preset boundary state of charge, determine the target temperature based on the current temperature and the temperature safety margin. The temperature safety margin is determined based on the temperature safety factor and the preset temperature gradient.

[0145] It should be noted that the preset boundary state of charge (SOC) is the set boundary SOC value, for example, SOC = 60%. This value can be set according to the actual situation and is not specifically limited. When the current SOC is lower than the preset boundary SOC, a continuous charging MAP needs to be established based on the temperature safety margin.

[0146] Temperature safety margin refers to the margin of safety for continuous charging when setting the MAP (Modular Temperature Parameter) based on the adjustment at the current temperature. εΔT is the charging capability corresponding to the lowered temperature value, used as the fast charging MAP value. Here, ε is the temperature safety factor, typically set to 1 or 2, and ΔT is the preset temperature gradient. It can be seen that the temperature safety margin is determined by the temperature safety factor and the preset temperature gradient; it is the product of the temperature safety factor and the preset temperature gradient. Lowering the current temperature according to the temperature safety margin yields the target temperature.

[0147] Step S503: Determine the target state of charge based on the current state of charge and the state of charge safety margin. The state of charge safety margin is determined based on the state of charge safety factor and the preset state of charge level.

[0148] It should be noted that the state of charge (SOC) safety margin refers to the charging capability corresponding to the increased SOC value when setting the continuous charging MAP, based on the current SOC and adjusting it upwards by βΔSOC. Here, β is the SOC safety factor, usually set to 1 or 2, and ΔSOC is the preset load gradient. Therefore, the SOC safety margin is determined by the SOC safety factor and the preset load gradient; it is the product of the two. Adjusting the current SOC upwards according to the SOC safety margin yields the target SOC.

[0149] Step S504: Based on the target temperature and target state of charge, determine the corresponding target maximum charging current in the charging performance data, and generate a continuous charging MAP at the current temperature based on the target maximum charging current.

[0150] Understandably, based on the target temperature and target state of charge, a suitable maximum charging current, i.e., the target maximum charging current, is found. This allows the final continuous charging MAP to be specified based on the target maximum charging current.

[0151] It should be understood that if the SOC value is high, the charging current is small and the difference is not significant. Therefore, when the current state of charge is greater than or equal to the preset boundary state of charge, the charging performance data corresponding to the target temperature and the current state of charge can be used to formulate the continuous charging MAP. That is, the target maximum charging current is determined according to the target temperature and the current state of charge to generate the continuous charging MAP at the current temperature.

[0152] For example, the maximum continuous charging capacity (charging current) of the battery cell at 20℃ and 25℃ is shown in Table 1. The preset temperature gradient ΔT = 5℃, the preset SOC gradient ΔSOC = 10%, the temperature safety factor ε = 1, the state of charge safety factor β = 1, and the pre-charge boundary state of charge is SOC = 60%. If the current temperature of the battery cell is 25℃ and the current state of charge is less than 60%, the temperature safety margin εΔT = 5℃ is calculated. Then, the current temperature is lowered by 5℃, and the charging capacity corresponding to the lowered temperature value is selected as the fast charging MAP value. That is, the target temperature is 20℃, and the charging capacity corresponding to 20℃ is selected. The state of charge safety margin βΔSOC = 10% is calculated. Then, the current state of charge is increased by 10%, and the charging capacity corresponding to the increased state of charge is selected as the fast charging MAP value. That is, the target state of charge is the current SOC + 10%, and the corresponding charging capacity is selected. If the current state of charge is greater than or equal to 60%, the corresponding charging capacity is determined according to the target temperature and the current state of charge. The final continuous charging MAP corresponding to 25℃ is shown in Table 2.

[0153] Table 1

[0154]

[0155] Table 2

[0156]

[0157] This embodiment provides a method for evaluating the continuous charging performance of lithium-ion batteries. Under different temperatures and states of charge, the method combines dynamic current method and three-electrode method to obtain linear curves of negative electrode potential and dynamic charging current, and sets a safe threshold line for lithium deposition potential on the negative electrode. By using the intersection of the linear curve and the safe threshold line, the maximum charging current of the cell under different temperatures and states of charge is determined, thus quickly and accurately evaluating the maximum continuous charging capability of the cell. At the same time, based on the maximum continuous charging capability of the cell, a continuous charging strategy and charging MAP are formulated to ensure the safety of the cell throughout its entire life cycle and achieve safe and efficient operation of the power battery.

[0158] This application also provides an evaluation device for the continuous charging performance of lithium-ion batteries, please refer to... Figure 6 The evaluation device for the continuous charging performance of lithium-ion batteries includes:

[0159] The parameter division module 10 is used to divide the working temperature range of the cell in the lithium-ion battery into multiple temperature ranges, set multiple characteristic temperatures in the temperature ranges according to a preset temperature gradient, and set multiple characteristic states of charge in the state of charge range according to a preset load gradient. The temperature ranges include at least a low temperature range, a normal temperature range, and a high temperature range.

[0160] The data calculation module 20 is used to select the target characteristic temperature from the temperature range, and based on the negative electrode potential safety threshold line and the linear curve of the negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the cell at each target characteristic temperature, determine the maximum charging current corresponding to different characteristic states of charge of the cell at each target characteristic temperature.

[0161] The data calculation module 20 is also used to determine the charging performance data of each temperature range based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature of each temperature range. Different strategies are used to determine the charging performance data for different temperature ranges.

[0162] The data calculation module 20 is also used to determine the charging performance data of the battery cell within the operating temperature range based on the charging performance data of each temperature range.

[0163] The performance evaluation module 30 is used to evaluate and verify the continuous charging performance of lithium-ion batteries at the current temperature based on the charging performance data of the battery cell within the operating temperature range and based on the dual safety margin dynamic adjustment strategy.

[0164] In one feasible implementation, the data calculation module 20 is also used to obtain the linear curve of the negative electrode potential and dynamic charging current of the battery cell under different characteristic charging states at various target characteristic temperatures.

[0165] Determine the intersection points of the negative electrode potential safety threshold line and each linear curve;

[0166] The charging current at the intersection of different characteristic states of charge of the battery cell at various target characteristic temperatures is taken as the maximum charging current.

[0167] In one feasible implementation, the data calculation module 20 is further configured to discharge the battery cell to a first state of charge according to a preset discharge current.

[0168] Based on the dynamic current testing strategy, the battery cell is charged at different target characteristic temperatures to charge the battery cell to the second state of charge. The dynamic current testing strategy uses multiple preset charging currents.

[0169] Based on the three-electrode strategy, the negative electrode potential data and battery voltage data of the cell are recorded during the charging test, and the variation curves of the negative electrode potential and state of charge of the cell at various target characteristic temperatures under different charging currents are generated.

[0170] Based on the variation curves of the negative electrode potential and state of charge of the battery cell at various target characteristic temperatures under different charging currents, the linear curves of the negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures are determined.

[0171] In one feasible implementation, the data calculation module 20 is also used to determine the charging current data and negative electrode potential data corresponding to different characteristic states of charge of the battery cell at each target characteristic temperature based on the change curves of the negative electrode potential and state of charge of the battery cell at each target characteristic temperature under different charging currents, and to filter out effective linear data.

[0172] By fitting the effective linear data corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures, linear curves of negative electrode potential and charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures are obtained.

[0173] In one feasible implementation, the data calculation module 20 is also used to determine the charging performance data of the room temperature region based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the room temperature region.

[0174] Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at target characteristic temperatures in the normal temperature and low temperature regions, a calculation model for the maximum charging current in the low temperature region is fitted, and the charging performance data in the low temperature region is determined based on the calculation model for the maximum charging current.

[0175] Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region, the maximum safe charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region is determined, and charging performance data of the high-temperature region is generated based on the maximum safe charging current.

[0176] In one feasible implementation, the data calculation module 20 is also used to obtain the maximum charging current of temperature rise corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high temperature zone.

[0177] Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the normal temperature range, the upper limit of the current in the normal temperature range corresponding to different characteristic states of charge is determined, and based on the upper limit of the current in the normal temperature range corresponding to different characteristic states of charge, the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high temperature range is adjusted.

[0178] Based on the principle of safety first, the minimum current is determined from the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature zone and the maximum charging current with temperature rise, and is taken as the maximum safe charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature zone.

[0179] In one feasible implementation, the data calculation module 20 is also used to obtain the correspondence between the cell specific heat capacity, cell mass, temperature difference, cell dynamic internal resistance and the maximum charging current of temperature rise.

[0180] Based on the specific heat capacity of the battery cell, the mass of the battery cell, the dynamic internal resistance of the battery cell, the temperature difference between the target characteristic temperature and the upper limit of the operating temperature in the high-temperature zone, and the corresponding relationship, the maximum charging current corresponding to the temperature rise of the battery cell at different characteristic states of charge under the target characteristic temperature in the high-temperature zone is determined.

[0181] In one feasible implementation, the performance evaluation module 30 is also used to obtain the current state of charge and the current temperature;

[0182] When the current state of charge is less than the preset boundary state of charge, the target temperature is determined based on the current temperature and the temperature safety margin. The temperature safety margin is determined based on the temperature safety factor and the preset temperature gradient.

[0183] The target state of charge is determined based on the current state of charge and the state of charge safety margin. The state of charge safety margin is determined based on the state of charge safety factor and the preset state of charge level.

[0184] Based on the target temperature and target state of charge, the corresponding target maximum charging current is determined from the charging performance data;

[0185] Based on the target maximum charging current, generate a continuous charging MAP at the current temperature.

[0186] The lithium-ion battery continuous charging performance evaluation device provided in this application adopts the lithium-ion battery continuous charging performance evaluation method in the above embodiments, which can solve the technical problems that traditional methods for evaluating the continuous charging performance of lithium-ion batteries are relatively complex, costly, and difficult to achieve quickly and accurately. Compared with the prior art, the beneficial effects of the lithium-ion battery continuous charging performance evaluation device provided in this application are the same as those of the lithium-ion battery continuous charging performance evaluation method provided in the above embodiments, and other technical features in the lithium-ion battery continuous charging performance evaluation device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0187] This application provides an evaluation device for the continuous charging performance of a lithium-ion battery. The evaluation device for the continuous charging performance of a lithium-ion battery includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the evaluation method for the continuous charging performance of a lithium-ion battery in the above embodiment 1.

[0188] The following is for reference. Figure 7This document illustrates a schematic diagram of a structure suitable for evaluating the continuous charging performance of lithium-ion batteries in accordance with embodiments of this application. The evaluation device for the continuous charging performance of lithium-ion batteries in embodiments of this application may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), and in-vehicle terminals (e.g., in-vehicle navigation terminals), as well as fixed terminals such as digital TVs and desktop computers. Figure 7 The illustrated device for evaluating the continuous charging performance of lithium-ion batteries is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0189] like Figure 7 As shown, the lithium-ion battery continuous charging performance evaluation device may include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from a storage device 1003 into a random access memory (RAM) 1004. The RAM 1004 also stores various programs and data required for the operation of the lithium-ion battery continuous charging performance evaluation device. The processing unit 1001, ROM 1002, and RAM 1004 are interconnected via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the lithium-ion battery continuous charging performance evaluation device to communicate wirelessly or wiredly with other devices to exchange data. Although the figure shows a lithium-ion battery continuous charging performance evaluation device with various systems, it should be understood that it is not required to implement or possess all the systems shown. More or fewer systems can be implemented alternatively.

[0190] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from ROM 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0191] The lithium-ion battery continuous charging performance evaluation device provided in this application, employing the lithium-ion battery continuous charging performance evaluation method described in the above embodiments, solves the technical problems of traditional methods being complex, costly, and difficult to implement quickly and accurately when evaluating the continuous charging performance of lithium-ion batteries. Compared with the prior art, the beneficial effects of the lithium-ion battery continuous charging performance evaluation device provided in this application are the same as those of the lithium-ion battery continuous charging performance evaluation method provided in the above embodiments, and other technical features in this lithium-ion battery continuous charging performance evaluation device are the same as those disclosed in the method of the previous embodiment, and will not be repeated here.

[0192] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0193] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0194] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to execute the method for evaluating the continuous charging performance of a lithium-ion battery in the above embodiments.

[0195] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0196] The aforementioned computer-readable storage medium carries one or more programs. When these programs are executed by an evaluation device for the continuous charging performance of a lithium-ion battery, the evaluation device causes the lithium-ion battery to: divide the operating temperature range of the battery cell into multiple temperature zones; set multiple characteristic temperatures within each temperature zone according to a preset temperature gradient; and set multiple characteristic states of charge within each state of charge range according to a preset load gradient. The temperature zones at least include a low-temperature zone, a normal-temperature zone, and a high-temperature zone. The device then selects a target characteristic temperature from the temperature zones, and based on the negative electrode potential safety threshold line and the negative electrode potential corresponding to different characteristic states of charge of the battery cell at each target characteristic temperature and the dynamic charging... The linear curve of the electric current is used to determine the maximum charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures. Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures in various temperature ranges, the charging performance data of each temperature range is determined. Different strategies are used to determine the charging performance data of different temperature ranges. Based on the charging performance data of each temperature range, the charging performance data of the battery cell within the operating temperature range is determined. Based on the charging performance data of the battery cell within the operating temperature range and based on a dual safety margin dynamic adjustment strategy, a corresponding continuous charging MAP is formulated to evaluate and verify the continuous charging performance of the lithium-ion battery at the current temperature.

[0197] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0198] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0199] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described method for evaluating the continuous charging performance of lithium-ion batteries. This solves the technical problems that traditional methods for evaluating the continuous charging performance of lithium-ion batteries are complex, costly, and difficult to implement quickly and accurately. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the lithium-ion battery continuous charging performance evaluation method provided in the above embodiments, and will not be repeated here.

[0200] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the method for evaluating the continuous charging performance of a lithium-ion battery as described above.

[0201] The computer program product provided in this application can solve the technical problems that traditional methods for evaluating the continuous charging performance of lithium-ion batteries are complex, costly, and difficult to implement quickly and accurately. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as those of the lithium-ion battery continuous charging performance evaluation method provided in the above embodiments, and will not be repeated here.

[0202] The above are only some embodiments of this application and do not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A method for evaluating the continuous charging performance of a lithium-ion battery, characterized in that, The method includes: The operating temperature range of the cell in the lithium-ion battery is divided into multiple temperature ranges. Multiple characteristic temperatures are set within the temperature ranges according to a preset temperature gradient, and multiple characteristic states of charge are set within the state of charge range according to a preset load gradient. The temperature ranges include at least a low temperature range, a normal temperature range, and a high temperature range. Select a target characteristic temperature from the temperature range, and determine the maximum charging current corresponding to different characteristic states of charge of the cell at each target characteristic temperature based on the negative electrode potential safety threshold line and the linear curve of negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the cell at each target characteristic temperature. Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in each temperature range, the charging performance data of each temperature range is determined, wherein different strategies are used to determine the charging performance data for different temperature ranges. Based on the charging performance data of each temperature range, the charging performance data of the battery cell within the operating temperature range is determined. Based on the charging performance data of the battery cell within the operating temperature range, and based on a dual safety margin dynamic adjustment strategy, a corresponding continuous charging MAP is formulated to evaluate and verify the continuous charging performance of the lithium-ion battery at the current temperature.

2. The method as described in claim 1, characterized in that, The step of determining the maximum charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures, based on the negative electrode potential safety threshold line and the linear curves of negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures, includes: Obtain linear curves of negative electrode potential versus dynamic charging current of the battery cell under different characteristic states of charge at various target characteristic temperatures; Determine the intersection points of the negative electrode potential safety threshold line with each linear curve; The charging current at the intersection of different characteristic states of charge of the battery cell at various target characteristic temperatures is taken as the maximum charging current.

3. The method as described in claim 2, characterized in that, The step of obtaining the linear curves of the negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures includes: The battery cell is discharged to the first state of charge according to the preset discharge current; Based on a dynamic current testing strategy, the battery cell is charged under different target characteristic temperatures to charge the battery cell to a second state of charge. The dynamic current testing strategy uses multiple preset charging currents. Based on the three-electrode strategy, the negative electrode potential data and battery voltage data of the cell are recorded during the charging test, and the variation curves of the negative electrode potential and state of charge of the cell at each target characteristic temperature under different charging currents are generated. Based on the variation curves of the negative electrode potential and state of charge of the battery cell at various target characteristic temperatures under different charging currents, the linear curves of the negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures are determined.

4. The method as described in claim 3, characterized in that, The step of determining the linear curves of the negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures based on the change curves of the negative electrode potential and state of charge of the battery cell at various target characteristic temperatures under different charging currents includes: Based on the variation curves of the negative electrode potential and state of charge of the battery cell at various target characteristic temperatures under different charging currents, the charging current data and negative electrode potential data corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures are determined, and effective linear data are selected. By fitting the effective linear data corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures, linear curves of negative electrode potential and charging current corresponding to different characteristic states of charge of the battery cell at various target characteristic temperatures are obtained.

5. The method as described in claim 1, characterized in that, The target characteristic temperature in the normal temperature zone is all the characteristic temperatures in the normal temperature zone; the target characteristic temperature in the low temperature zone is a preset number of characteristic temperatures selected in the low temperature zone; the target characteristic temperature in the high temperature zone is all the characteristic temperatures in the high temperature zone; the step of determining the charging performance data for each temperature zone based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperatures in each temperature zone includes: Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the room temperature range, the charging performance data in the room temperature range is determined. Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at target characteristic temperatures in the normal temperature and low temperature regions, a calculation model for the maximum charging current in the low temperature region is fitted, and based on the calculation model for the maximum charging current, the charging performance data in the low temperature region is determined. Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region, the maximum safe charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region is determined, and charging performance data of the high-temperature region is generated based on the maximum safe charging current.

6. The method as described in claim 5, characterized in that, The step of determining the maximum safe charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region, based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region, includes: Obtain the maximum charging current for temperature rise corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region; Based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the normal temperature range, the upper limit of the current in the normal temperature range corresponding to different characteristic states of charge is determined, and based on the upper limit of the current in the normal temperature range corresponding to different characteristic states of charge, the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high temperature range is adjusted. Based on the principle of safety first, the minimum current is determined from the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region and the maximum charging current with temperature rise, and is taken as the maximum safe charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region.

7. The method as described in claim 6, characterized in that, The step of obtaining the maximum charging current for temperature rise corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature in the high-temperature region includes: Obtain the corresponding relationship between cell specific heat capacity, cell mass, temperature difference, cell dynamic internal resistance and maximum charging current at temperature rise; Based on the cell's specific heat capacity, cell mass, cell dynamic internal resistance, the temperature difference between the target characteristic temperature and the upper limit of the operating temperature in the high-temperature zone, and the corresponding relationship, the maximum charging current corresponding to different characteristic states of charge of the cell at the target characteristic temperature in the high-temperature zone is determined.

8. The method according to any one of claims 1 to 7, characterized in that, The steps for evaluating and verifying the continuous charging performance of the lithium-ion battery at the current temperature, based on the charging performance data of the battery cell within the operating temperature range and a dual safety margin dynamic adjustment strategy, include: Get the current state of charge and the current temperature; When the current state of charge is less than the preset boundary state of charge, the target temperature is determined based on the current temperature and the temperature safety margin, wherein the temperature safety margin is determined based on the temperature safety factor and the preset temperature gradient. Based on the current state of charge and the state of charge safety margin, the target state of charge is determined, wherein the state of charge safety margin is determined based on the state of charge safety factor and the preset load gradient. Based on the target temperature and the target state of charge, the corresponding target maximum charging current is determined from the charging performance data; Based on the target maximum charging current, a continuous charging MAP is generated at the current temperature.

9. An evaluation device for the continuous charging performance of a lithium-ion battery, characterized in that, The evaluation device for the continuous charging performance of the lithium-ion battery includes: The parameter division module is used to divide the working temperature range of the cell in the lithium-ion battery into multiple temperature ranges, set multiple characteristic temperatures in the temperature ranges according to a preset temperature gradient, and set multiple characteristic states of charge in the state of charge range according to a preset load gradient. The temperature ranges include at least a low temperature range, a normal temperature range, and a high temperature range. The data calculation module is used to select a target characteristic temperature from the temperature range, and based on the negative electrode potential safety threshold line and the linear curve of the negative electrode potential and dynamic charging current corresponding to different characteristic states of charge of the cell at each target characteristic temperature, determine the maximum charging current corresponding to different characteristic states of charge of the cell at each target characteristic temperature. The data calculation module is also used to determine the charging performance data of each temperature range based on the maximum charging current corresponding to different characteristic states of charge of the battery cell at the target characteristic temperature of each temperature range. Different strategies are used to determine the charging performance data for different temperature ranges. The data calculation module is also used to determine the charging performance data of the battery cell within the operating temperature range based on the charging performance data of each temperature range. The performance evaluation module is used to evaluate and verify the continuous charging performance of the lithium-ion battery at the current temperature based on the charging performance data of the battery cell within the operating temperature range and based on the dual safety margin dynamic adjustment strategy, and to formulate the corresponding continuous charging MAP.

10. An evaluation device for the continuous charging performance of a lithium-ion battery, characterized in that, The device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the method for evaluating the continuous charging performance of a lithium-ion battery as claimed in any one of claims 1 to 8.

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