A charging strategy lithium precipitation boundary window evaluation method and system

Abstract

The application provides a lithium precipitation boundary window evaluation method and system of a charging strategy, and belongs to the field of lithium ion batteries. The method comprises the following steps: preparing a lithium ion battery comprising a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte; performing a rate charging test on the lithium ion battery at a set rate to obtain the constant current charging capacity and the constant current constant voltage charging capacity of the battery at different rates, and calculating the constant current injection ratio; calculating the maximum SOC of the battery when reaching the lithium precipitation boundary at different charging rates, and formulating a step charging strategy according to the maximum SOC; performing a battery charging and discharging cycle test according to the obtained step charging strategy, and determining the lithium precipitation condition of the battery. The application can quickly and efficiently evaluate the lithium precipitation boundary window without relying on a three-electrode tool and a special battery device, and the formulated charging strategy can ensure that the battery does not precipitate lithium under fast charging conditions, thereby significantly improving the fast charging strategy formulation efficiency and the cycle performance and safety of the battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, and particularly relates to a method and system for evaluating the lithium plating boundary window of a charging strategy. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In recent years, with the rapid development of electric vehicles, portable electronic devices, and energy storage systems, the demand for fast charging technology for lithium-ion batteries, as core energy storage devices, has become increasingly urgent. Fast charging can significantly improve the user experience, but it also brings challenges to battery life and safety. During fast charging, especially under conditions of low temperature, high state of charge (SOC), or high current charging, the polarization phenomenon inside the battery intensifies, which may lead to lithium metal deposition on the negative electrode surface. Lithium deposition not only consumes active lithium ions, causing battery capacity decay, but also triggers exothermic side reactions such as electrolyte decomposition and internal short circuits, increasing the risk of battery thermal runaway and even fire and explosion, seriously threatening battery safety performance.

[0004] Currently, the industry primarily assesses the lithium plating boundary by real-time monitoring of the negative electrode potential using a three-electrode battery system, and formulates charging strategies accordingly. However, this strategy heavily relies on three-electrode tooling, requiring the pre-fabrication of specialized battery devices. The fabrication process for these specialized devices is technically demanding, cumbersome, and has a low success rate. Furthermore, due to the strong internal polarization of the battery, reproducible experimental results are difficult to obtain, and a certain "hysteresis" exists between the actual lithium plating situation inside the battery and the negative electrode potential, leading to measurement errors. Additionally, the long cycle from battery fabrication to testing completion cannot meet the need for rapid development of fast-charging strategies. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a method and system for evaluating the lithium plating boundary window of a charging strategy. By combining the cell's coating areal density (AD), compaction density (CD), and constant current charge ratio (CC) with the charge rate (C), the maximum state of charge (SOC) at which the cell reaches the lithium plating boundary is calculated, thereby formulating a safe fast-charging strategy. This invention eliminates the need for cumbersome special battery devices and can quickly evaluate the battery's lithium plating potential, formulating a battery charging strategy to prevent lithium plating under fast-charging conditions.

[0006] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions: The first aspect of this invention provides a method for evaluating the lithium plating boundary window of a charging strategy; A method for evaluating the lithium plating boundary window of a charging strategy includes: To manufacture a lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte; The lithium-ion battery was subjected to a rate charging test at a set rate to obtain the constant current charging capacity and constant current constant voltage charging capacity of the battery at different rates, and the constant current charge ratio was calculated. Calculate the maximum SOC of the cell when it reaches the lithium plating boundary under different charging rates, and formulate a stepped charging strategy based on the maximum SOC. Based on the obtained stepped charging strategy, cell charge-discharge cycle tests were conducted to determine the lithium plating status of the cells.

[0007] As a further technical solution, the fabrication of a lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte includes: The positive electrode active material is mixed with a conductive agent and a binder in a preset mass ratio, and a solvent is added and stirred thoroughly to form a positive electrode slurry. The positive electrode slurry is coated onto a positive electrode current collector, and then dried, rolled, and cut into sheets to obtain a positive electrode sheet. The negative electrode active material is mixed with a conductive agent and a binder in a preset mass ratio, and a solvent is added to fully dissolve and stir to form a negative electrode slurry; the negative electrode slurry is coated onto a negative electrode current collector, and after drying, rolling, and cutting, a negative electrode sheet is obtained; The positive electrode, negative electrode, and separator are stacked or wound to form an electrode assembly, which is then hot-pressed. The hot-pressed electrode assembly is then inserted into a battery casing, baked, and injected with electrolyte. Subsequently, it is encapsulated, formed, and capacity-tested to obtain the lithium-ion battery.

[0008] As a further technical solution, the positive electrode sheet double-sided coating surface density The compacted surface density of the positive electrode sheet is 2.5-2.7. The compacted surface density of the negative electrode sheet is 1.5-1.7. .

[0009] As a further technical solution, the active material of the positive electrode includes at least one of lithium iron phosphate, lithium manganese iron phosphate, ternary materials, and sodium ion positive electrode materials; the active material of the negative electrode includes at least one of graphite, silicon-oxygen materials, and modified silicon-oxygen materials.

[0010] As a further technical solution, the step of performing a rate charging test on the lithium-ion battery at a set rate to obtain the constant current charging capacity and constant current constant voltage charging capacity of the battery at different rates, and calculating the constant current charge-in ratio, includes: Place the lithium-ion battery to be tested in a room temperature environment and let it stand until the battery temperature is the same as the ambient temperature. The lithium-ion battery is charged with constant current and constant voltage at different set charging rates; Record the charging capacity during the constant current phase of the above charging process as the constant current charging capacity; record the total charging capacity of the constant current phase and the constant voltage phase as the constant current and constant voltage charging capacity. The constant current charging ratio of the lithium-ion battery at different set rates is calculated based on the constant current charging capacity and the constant current and constant voltage charging capacity.

[0011] As a further technical solution, the maximum SOC of the battery cell when it reaches the lithium plating boundary under different charging rates is calculated, and a stepped charging strategy is formulated based on the maximum SOC, including: The compaction density of the positive electrode sheet, the coating density of the positive electrode sheet, the compaction density of the negative electrode sheet, and the constant current charge ratio under different charging rates were obtained. The maximum SOC of the cell at this charging rate when it reaches the lithium plating boundary is calculated as follows:

[0012] in, This refers to the compaction density of the positive electrode sheet; This refers to the compaction density of the negative electrode sheet; For constant current input ratio; The surface density of the coating on the positive electrode sheet; The charging rate of the battery cell.

[0013] Based on the correlation between different charging rates C and the corresponding calculated maximum SOC, a stepped charging strategy for the battery cell is constructed.

[0014] As a further technical solution, the step of performing cell charge-discharge cycle testing based on the obtained stepped charging strategy to determine the lithium plating status of the cell includes: Place the lithium-ion battery to be tested in a room temperature environment and let it stand to ensure that the battery temperature is the same as the ambient temperature. A stepped charging strategy was used to conduct charge-discharge cycle tests on lithium-ion batteries. The charging process was carried out according to the stepped charging strategy until the battery voltage reached the cutoff voltage of 3.65V. The discharging process was carried out at a constant current of 1C to 2.0V. The above charge-discharge process was repeated until the set number of cycles was reached. After completing the set number of cycles, charge the lithium-ion battery to the cutoff voltage of 3.65V according to the stepped charging strategy, let it stand, and then disassemble it to remove the negative electrode plate. The presence of residual floating lithium on the surface of the negative electrode is assessed. If no residual floating lithium area appears on the surface of the negative electrode, the cell interface is considered to be in good condition and there is no lithium plating. If residual floating lithium area appears on the surface of the negative electrode, the cell is considered to have undergone lithium plating.

[0015] A charging strategy lithium plating boundary window evaluation system, comprising: The lithium-ion battery manufacturing module is configured to: manufacture a lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte; The rate charging test module is configured to: perform a rate charging test on the lithium-ion battery at a set rate, obtain the constant current charging capacity and constant current constant voltage charging capacity of the battery at different rates, and calculate the constant current charging ratio. The stepped charging strategy formulation module is configured to: calculate the maximum SOC of the cell when it reaches the lithium plating boundary under different charging rates, and formulate a stepped charging strategy based on the maximum SOC. The cell lithium plating determination module is configured to perform cell charge-discharge cycle tests based on the obtained stepped charging strategy to determine the cell lithium plating status.

[0016] A third aspect of the present invention provides a computer-readable storage medium having a program stored thereon that, when executed by a processor, implements the steps of a lithium plating boundary window evaluation method for a charging strategy as described in the first aspect of the present invention.

[0017] A fourth aspect of the present invention provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps in a lithium plating boundary window evaluation method for a charging strategy as described in the first aspect of the present invention.

[0018] The above one or more technical solutions have the following beneficial effects: This invention assesses the lithium plating boundary by combining the cell's electrode parameters (area density, compaction density) and the measured constant current charge ratio with mathematical formulas, eliminating the need for cumbersome three-electrode battery fabrication. This not only simplifies the experimental process and reduces the requirements for specialized equipment fabrication techniques but also improves the success rate of experiments and significantly reduces evaluation costs. By establishing a quantitative relationship between SOC and charging rate, the maximum SOC at which the cell reaches the lithium plating boundary can be directly calculated at different charging rates, enabling rapid generation of stepped charging strategies. Compared to the complex process of traditional three-electrode testing, this method significantly shortens the development cycle of fast charging strategies and substantially improves the efficiency of fast charging cell R&D.

[0019] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a flowchart of the method in the first embodiment.

[0022] Figure 2 This is a system structure diagram of the second embodiment. Detailed Implementation

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0025] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0026] Example 1 This embodiment discloses a method for evaluating the lithium plating boundary window of a charging strategy; like Figure 1 As shown, a method for evaluating the lithium plating boundary window in a charging strategy includes: Step S101: Fabricate a lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte; Step S102: Perform a rate charging test on the lithium-ion battery at a set rate to obtain the constant current charging capacity and constant current constant voltage charging capacity of the battery at different rates, and calculate the constant current charging ratio. Step S103: Calculate the maximum SOC of the cell when it reaches the lithium plating boundary under different charging rates, and formulate a stepped charging strategy based on the maximum SOC. Step S104: Perform cell charge-discharge cycle tests according to the obtained stepped charging strategy to determine the lithium plating status of the cell.

[0027] Specifically, it also includes the following: Step S101: Fabricate a lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte.

[0028] Specifically, in the preparation of the positive electrode of a lithium-ion battery, the positive electrode active material is mixed with a conductive agent and a binder at a preset mass ratio, and a solvent is added and stirred thoroughly to form a positive electrode slurry; the positive electrode slurry is coated onto a positive electrode current collector, and after drying, rolling, and cutting, a positive electrode sheet is obtained; wherein, the positive electrode active material includes at least one of lithium iron phosphate, lithium manganese iron phosphate, ternary materials, and sodium-ion positive electrode materials, the positive electrode current collector is carbon-coated aluminum foil, and the positive electrode sheet has a double-sided coating density. Preferred The compaction density of the positive electrode sheet is 2.3-2.8. The preferred value is 2.5-2.7. .

[0029] In the preparation process of the negative electrode of a lithium-ion battery, the negative electrode active material, conductive agent, and binder are mixed at a preset mass ratio, and a solvent is added to fully dissolve and stir to form a negative electrode slurry. The negative electrode slurry is coated onto a negative electrode current collector, and after drying, rolling, and cutting, a negative electrode sheet is obtained. The negative electrode active material includes at least one of graphite, silicon oxide materials, and modified silicon oxide materials; the negative electrode current collector is copper foil; and the compacted surface density of the negative electrode sheet is 1.3-1.8. The preferred value is 1.5-1.7. .

[0030] Finally, the prepared positive electrode, negative electrode, and separator are stacked or wound to form an electrode assembly, and the electrode assembly is hot-pressed. The hot-pressed electrode assembly is then inserted into the battery casing, baked, and injected with electrolyte. Subsequently, it is encapsulated, formed, and capacity tested to obtain the lithium-ion battery. The separator is used to isolate the positive electrode and negative electrode to prevent short circuits, and the electrolyte is a lithium-ion conductor, providing an ion conduction channel.

[0031] Step S102: Perform a rate charging test on the lithium-ion battery at a set rate to obtain the constant current charging capacity and constant current constant voltage charging capacity of the battery at different rates, and calculate the constant current charging ratio.

[0032] Specifically, the test preparation begins by placing the lithium-ion battery to be tested in a room temperature environment (25°C) until the battery temperature matches the ambient temperature. Then, the lithium-ion battery is charged using different set charging rates C (e.g., 1C, 2C, 3C) under constant current and constant voltage conditions. During the constant current phase, charging is performed at the set rate C until the battery voltage reaches the cutoff voltage of 3.65V. Subsequently, the constant voltage phase is initiated, maintaining the voltage at 3.65V and continuing charging until the charging current drops to 0.05C. Next, the charging capacity during the constant current phase is recorded; this is the constant current charging capacity. The total charging capacity during both the constant current and constant voltage phases is also recorded; this is the constant current and constant voltage charging capacity. Finally, the constant current charge ratio (CC) of the lithium-ion battery at different set rates is calculated using the formula "Constant Current Charge Ratio CC = Constant Current Charging Capacity / Constant Current and Constant Voltage Charging Capacity". The constant current charge ratio is expressed as a percentage.

[0033] Step S103: Calculate the maximum SOC of the cell when it reaches the lithium plating boundary under different charging rates, and formulate a stepped charging strategy based on the maximum SOC.

[0034] Based on the obtained compaction density of the positive electrode sheet, the coating density of the positive electrode sheet, the compaction density of the negative electrode sheet, and the constant current charge ratio at different charging rates obtained through rate charging tests, for each set charging rate, the maximum SOC of the cell when it reaches the lithium plating boundary is calculated according to the following formula, as shown below:

[0035] in, This refers to the compaction density of the positive electrode sheet; This refers to the compaction density of the negative electrode sheet; For constant current input ratio; The surface density of the coating on the positive electrode sheet; The charging rate of the battery cell.

[0036] Based on the correlation between different charging rates C and the corresponding calculated maximum SOC, a stepped charging strategy for the battery cell is constructed. This strategy limits the charging process to the following: when the current SOC of the battery cell does not exceed the maximum SOC under the corresponding charging rate, the charging rate is used for charging; when the current SOC of the battery cell reaches or exceeds the maximum SOC under the corresponding charging rate, the charging rate is switched to a lower charging rate to ensure that lithium plating does not occur in the battery cell during charging.

[0037] Step S104: Perform cell charge-discharge cycle tests according to the obtained stepped charging strategy to determine the lithium plating status of the cell.

[0038] The lithium-ion battery to be tested was placed in an environment at room temperature of 25°C and left to stand to ensure that the battery temperature was consistent with the ambient temperature. The lithium-ion battery was subjected to charge-discharge cycle tests according to the obtained stepped charging strategy. The charging process was carried out according to the stepped charging strategy until the battery voltage reached the cutoff voltage of 3.65V. The discharging process was carried out at a constant current of 1C to 2.0V. The above charge-discharge process was repeated until the set number of cycles was reached. After completing the set number of cycles, charge the lithium-ion battery to the cutoff voltage of 3.65V according to the stepped charging strategy, let it stand, and then disassemble it to remove the negative electrode plate. The presence of residual floating lithium on the surface of the negative electrode is assessed. If no residual floating lithium area appears on the surface of the negative electrode, the cell interface is considered to be in good condition and there is no lithium plating. If residual floating lithium area appears on the surface of the negative electrode, the cell is considered to have undergone lithium plating.

[0039] Furthermore, in this embodiment, a control group and an experimental group are set up for comparative experiments to verify the effectiveness of the method of the present invention.

[0040] In the control group, lithium iron phosphate cathode material was mixed with carbon black Super-P, conductive paste CNT carbon nanotubes, and binder vinylidene fluoride PVDF in a mass ratio of 96.5:1:0.5:2. NMP was added and stirred thoroughly to dissolve the mixture, resulting in a cathode paste. The cathode paste was then coated onto a 12µm carbon-coated aluminum foil, dried, rolled, and cut to obtain the cathode sheet. The areal density of the coating on both sides was set to 400. and 500 The compaction density was set to 2.55. and 2.7 .

[0041] The negative electrode graphite material was mixed with carbon black Super-P, binder CMC and SBR in a mass ratio of 96:1:1.2:1.8, and then dissolved and stirred in pure water to obtain a negative electrode slurry. The negative electrode slurry was coated onto a 6µm copper foil, and after drying, rolling, and cutting, a negative electrode sheet was obtained, with a compaction density of 1.55. and 1.7 .

[0042] The prepared positive and negative electrode sheets are stacked with the separator to obtain the corresponding electrode rolls, which are then hot-pressed. After hot pressing, the rolls are placed into the casing, baked, and then injected with liquefaction to form capacity, thus obtaining a lithium-ion battery. A short-term rate charging test is then conducted.

[0043] Using 0 V as the lithium plating potential of the battery cell, according to At a charging rate C, the maximum SOC of the cell when it reaches the lithium plating boundary is calculated, thereby obtaining the relationship between the cell SOC and the charging rate C, and further formulating the cell charging strategy for stepped cycle testing.

[0044] Furthermore, in the experimental group, the preparation methods for the positive and negative electrode sheets and the lithium-ion battery were the same. Regarding the formulation of the fast-charging strategy, based on... At a charging rate of C, the minimum state of charge (SOC) when the cell reaches the lithium plating boundary is calculated. A stepped charging strategy for the cell is then formulated based on the condition that the SOC is greater than this, and stepped cycle tests are conducted.

[0045] Furthermore, a rate charging test was first conducted, as shown in Table 1. At room temperature (25℃), the cells were charged at different rates (1C, 2C, 3C) using constant current and constant voltage to 3.65V, and then discharged at 1C using constant current to 2.0V. After the rate charging test was completed, the constant current charging capacity and constant current and constant voltage charging capacity were obtained. The constant current charging ratio = constant current charging capacity / constant current and constant voltage charging capacity.

[0046] Table 1. Test data of lithium-ion batteries under high rate charging.

[0047] Subsequently, a stepped cycle test was conducted, as shown in Table 2. At room temperature (25℃), the cell SOC was charged to 3.65V and then discharged at 1C to 2.0V using the relationship between cell SOC and rate (C). After 1000 cycles, the lithium-ion battery was charged to the cutoff voltage using a stepped charging strategy. The negative electrode was then disassembled, and the residual lithium on its surface was observed. A residual lithium area of ​​less than or equal to 0% on the negative electrode surface was considered a good interface, while a residual lithium area greater than 0% was considered lithium plating.

[0048] Table 2 Results of Stepped Cycle Test

[0049] The results above show that the present invention can quickly evaluate the SOC state of a battery cell when it reaches the lithium plating boundary under charging rate conditions, obtain a fast charging strategy for the battery cell, effectively solve the problem of lithium plating during battery cell cycles, and no longer heavily rely on three-electrode tooling, eliminating the need to prepare special battery devices in advance. The method is faster and significantly improves the efficiency of formulating fast charging strategies.

[0050] Example 2 This embodiment discloses a lithium plating boundary window evaluation system for charging strategies; like Figure 2 As shown, a lithium plating boundary window evaluation system for charging strategies includes: The lithium-ion battery manufacturing module 201 is configured to manufacture a lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte. The rate charging test module 202 is configured to: perform a rate charging test on the lithium-ion battery at a set rate, obtain the constant current charging capacity and constant current constant voltage charging capacity of the battery at different rates, and calculate the constant current charging ratio. The stepped charging strategy formulation module 203 is configured to: calculate the maximum SOC of the cell when it reaches the lithium plating boundary under different charging rates, and formulate a stepped charging strategy based on the maximum SOC. The cell lithium plating determination module 204 is configured to: perform cell charge-discharge cycle tests according to the obtained step-by-step charging strategy to determine the cell lithium plating status.

[0051] Example 3 The purpose of this embodiment is to provide a computer-readable storage medium.

[0052] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in a lithium plating boundary window evaluation method for a charging strategy as described in Example 1.

[0053] Example 4 The purpose of this embodiment is to provide an electronic device.

[0054] An electronic device includes a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in a lithium plating boundary window evaluation method for a charging strategy as described in Example 1.

[0055] The steps and methods involved in the apparatuses of Embodiments 2, 3, and 4 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0056] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0057] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for evaluating the lithium plating boundary window of a charging strategy, characterized in that, include: To manufacture a lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte; The lithium-ion battery was subjected to a rate charging test at a set rate to obtain the constant current charging capacity and constant current constant voltage charging capacity of the battery at different rates, and the constant current charge ratio was calculated. Calculate the maximum SOC of the cell when it reaches the lithium plating boundary under different charging rates, and formulate a stepped charging strategy based on the maximum SOC. Based on the obtained tiered charging strategy, cell charge-discharge cycle tests are conducted to determine the lithium plating status of the cells. Calculate the maximum state of charge (SOC) of the battery cell when it reaches the lithium plating boundary under different charging rates, and formulate a stepped charging strategy based on the maximum SOC, including: The compaction density of the positive electrode sheet, the coating density of the positive electrode sheet, the compaction density of the negative electrode sheet, and the constant current charge ratio under different charging rates were obtained. The maximum SOC of the cell at this charging rate when it reaches the lithium plating boundary is calculated as follows: in, This refers to the compaction density of the positive electrode sheet; This refers to the compaction density of the negative electrode sheet; For constant current input ratio; The surface density of the coating on the positive electrode sheet; The charging rate of the battery cell; Based on the correlation between different charging rates C and the corresponding calculated maximum SOC, a stepped charging strategy for the battery cell is constructed.

2. The method for evaluating the lithium plating boundary window of a charging strategy as described in claim 1, characterized in that, The fabrication of a lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte includes: The positive electrode active material is mixed with a conductive agent and a binder in a preset mass ratio, and a solvent is added and stirred thoroughly to form a positive electrode slurry. The positive electrode slurry is coated onto a positive electrode current collector, and then dried, rolled, and cut into sheets to obtain a positive electrode sheet. The negative electrode active material is mixed with a conductive agent and a binder in a preset mass ratio, and a solvent is added and stirred thoroughly to form a negative electrode slurry. The negative electrode slurry is coated onto a negative electrode current collector, and then dried, rolled, and cut into sheets to obtain a negative electrode sheet. The positive electrode sheet, negative electrode sheet and separator are stacked or wound to form an electrode assembly, and the electrode assembly is hot-pressed; the hot-pressed electrode assembly is put into the battery casing, baked and then injected with electrolyte, and then encapsulated, formed and capacity tested to obtain a lithium-ion battery.

3. The method for evaluating the lithium plating boundary window of a charging strategy as described in claim 2, characterized in that, The positive electrode sheet has a double-sided coating surface density. The compaction density of the positive electrode sheet is 2.5-2.

7. The compacted density of the negative electrode sheet is 1.5-1.

7. .

4. The method for evaluating the lithium plating boundary window of a charging strategy as described in claim 2, characterized in that, The active material of the positive electrode includes at least one of lithium iron phosphate, lithium manganese iron phosphate, and ternary materials; the active material of the negative electrode includes at least one of graphite and silicon oxide materials.

5. The method for evaluating the lithium plating boundary window of a charging strategy as described in claim 1, characterized in that, The step of performing a rate charging test on the lithium-ion battery at a set rate to obtain the constant current charging capacity and constant current constant voltage charging capacity of the battery at different rates, and calculating the constant current charge-in ratio, includes: Place the lithium-ion battery to be tested in a room temperature environment and let it stand until the battery temperature is the same as the ambient temperature. The lithium-ion battery is charged with constant current and constant voltage at different set charging rates; Record the charging capacity during the constant current phase of the above charging process as the constant current charging capacity; record the total charging capacity of the constant current phase and the constant voltage phase as the constant current and constant voltage charging capacity. The constant current charging ratio of the lithium-ion battery at different set rates is calculated based on the constant current charging capacity and the constant current and constant voltage charging capacity.

6. The method for evaluating the lithium plating boundary window of a charging strategy as described in claim 1, characterized in that, The step of performing cell charge-discharge cycle tests based on the obtained stepped charging strategy to determine the lithium plating status of the cell includes: Place the lithium-ion battery to be tested in a room temperature environment and let it stand to ensure that the battery temperature is the same as the ambient temperature. A stepped charging strategy was used to conduct charge-discharge cycle tests on lithium-ion batteries. The charging process was carried out according to the stepped charging strategy until the battery voltage reached the cutoff voltage of 3.65V. The discharging process was carried out at a constant current of 1C to 2.0V. The above charge-discharge process was repeated until the set number of cycles was reached. After completing the set number of cycles, charge the lithium-ion battery to the cutoff voltage of 3.65V according to the stepped charging strategy, let it stand, and then disassemble it to remove the negative electrode plate. The presence of residual floating lithium on the surface of the negative electrode is assessed. If no residual floating lithium area appears on the surface of the negative electrode, the cell interface is considered to be in good condition and there is no lithium plating. If residual floating lithium area appears on the surface of the negative electrode, the cell is considered to have undergone lithium plating.

7. A lithium plating boundary window evaluation system for charging strategies, using the lithium plating boundary window evaluation method for charging strategies as described in any one of claims 1-6, characterized in that: include: The lithium-ion battery manufacturing module is configured to: manufacture a lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte; The rate charging test module is configured to: perform a rate charging test on the lithium-ion battery at a set rate, obtain the constant current charging capacity and constant current constant voltage charging capacity of the battery at different rates, and calculate the constant current charging ratio. The stepped charging strategy formulation module is configured to: calculate the maximum SOC of the cell when it reaches the lithium plating boundary under different charging rates, and formulate a stepped charging strategy based on the maximum SOC. The cell lithium plating determination module is configured to perform cell charge-discharge cycle tests based on the obtained stepped charging strategy to determine the cell lithium plating status.

8. A computer-readable storage medium having a program stored thereon, characterized in that, When executed by the processor, the program implements the steps in the lithium plating boundary window evaluation method for a charging strategy as described in any one of claims 1-6.

9. An electronic device comprising a memory, a processor, and a program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the lithium plating boundary window evaluation method for a charging strategy as described in any one of claims 1-6.

Images