Method for quickly adjusting lithium ion battery fast charging cycle life and energy density

Abstract

The present application relates to the technical field of lithium ion secondary battery, in particular to a method for quickly adjusting the fast charging cycle life and energy density of lithium ion battery. The method comprises the steps of calculating energy density, testing cycle life, calculating balance factor and adjusting preset parameters. After adjusting the preset parameters, the steps of calculating energy density, testing cycle life, calculating balance factor and adjusting preset parameters are repeated until the cycle life meets the preset requirements. The method can quickly and effectively adjust the design parameters by adjusting the size of the balance factor, thereby estimating the cycle life before preparing the battery sample, reducing the number of repeated verifications, and significantly shortening the development cycle of lithium ion battery.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion secondary battery technology, and specifically to a method for rapidly adjusting the fast-charging cycle life and energy density of lithium-ion batteries. Background Technology

[0002] Lithium-ion rechargeable batteries possess long cycle life and excellent fast-charging performance, making them a promising candidate for energy storage, particularly in frequency regulation energy storage. In typical lithium-ion battery designs, to achieve ultra-long cycle life, highly stable positive and negative electrode active materials are often selected to ensure continued performance under long-term cycling conditions. To achieve fast charging, in addition to selecting positive and negative electrode active materials with fast-charging capabilities, it is also necessary to reduce the areal density of the positive and negative electrode coatings and lower the current density during charging and discharging.

[0003] However, the cycle life of positive and negative electrode active materials with superior fast-charging performance is often not advantageous, leading to certain limitations in material selection. Secondly, ultra-long cycle life (20,000 or even 30,000 cycles or more) places very high demands on materials, and few materials can meet these requirements. Furthermore, current development methods for lithium-ion rechargeable batteries often involve first manufacturing a finished battery, then testing its charging speed and cycle life. The test results are compared with design goals, and once discrepancies are identified, parameters are adjusted, and another finished battery is manufactured. This process is repeated until a battery that meets the requirements is obtained. However, the production cycle of lithium-ion batteries is relatively long, and the verification of ultra-long cycle life requires a considerable amount of time, resulting in a lengthy overall development cycle and significant room for improvement in development efficiency. Summary of the Invention

[0004] In view of this, the present invention provides a method for rapidly adjusting the fast-charging cycle life and energy density of lithium-ion batteries. When the fast-charging cycle life of the designed lithium-ion battery sample does not meet the preset requirements after testing, this method can quickly and effectively adjust the design parameters by adjusting the size of the balance factor, reducing the number of repeated adjustments and tests, and significantly shortening the development cycle of lithium-ion batteries.

[0005] To address the above technical problems, this invention provides a method for rapidly adjusting the fast-charging cycle life and energy density of lithium-ion batteries, comprising the following steps: Calculate energy density: Based on the preset parameters of the lithium-ion battery, calculate the theoretical energy density of the lithium-ion battery to make it meet the preset energy density requirements; Cycle life test: Prepare battery samples according to the preset parameters and test the cycle life of the battery samples; Calculate the balance factor: When the cycle life does not meet the preset cycle life requirement, obtain the utilization rate and coating density of the positive electrode material in the positive electrode sheet of the lithium-ion battery, and the utilization rate and coating density of the negative electrode material in the negative electrode sheet. Input the utilization rate and coating density of the positive and negative materials into the evaluation model to obtain the balance factor. The evaluation model is obtained by fusing the utilization rate and coating density of the positive and negative electrode materials. Adjusting preset parameters: Based on the balance factor, determine the adjustment direction of the utilization rate and coating density of the positive and negative electrode materials, and redesign the preset parameters; Repeat the steps of calculating energy density, testing cycle life, calculating balance factor, and adjusting preset parameters until the cycle life meets the preset requirements.

[0006] In one possible implementation, the calculation of the balance factor specifically involves: When the cycle life does not meet the preset cycle life requirement, the utilization rate of the positive electrode material in the positive electrode sheet and the areal density of the positive electrode sheet coating are obtained, as well as the utilization rate of the negative electrode material in the negative electrode sheet and the areal density of the negative electrode sheet coating are obtained. The utilization rates of the positive and negative electrode materials and the areal density of the corresponding electrode sheets are input into the evaluation model to obtain the balance factor; wherein, the evaluation model is obtained by weighted fusion processing of the utilization rates of the positive and negative electrode materials and the areal density of the corresponding electrode sheets.

[0007] In one possible implementation, the evaluation model is obtained by summing the utilization rate of the positive electrode material, the utilization rate of the negative electrode material, the areal density of the positive electrode coating, and the areal density of the negative electrode coating according to a preset ratio.

[0008] In one possible implementation, the evaluation model is:

[0009] Where x is the balance factor, dimensionless; a is the utilization rate of the positive electrode material, in %; b is the utilization rate of the negative electrode material, in %; C a The areal density of the coating on the positive electrode sheet, in g / m². 2 Double-sided; C b The areal density of the negative electrode coating, expressed in g / m³. 2 It is a double-sided structure; both m and n are constants and dimensionless.

[0010] In one possible implementation, the constant m has a value of 0.14 to 0.16, and the constant n has a value of 2580 to 2620.

[0011] In one possible implementation, if the calculated theoretical energy density meets the preset energy density requirements, the larger the value of the balance factor x, the longer the fast-charging cycle life of the lithium-ion battery; the smaller the value of the balance factor x, the shorter the fast-charging cycle life of the lithium-ion battery.

[0012] In one possible implementation, determining the adjustment direction of the utilization rate and coating density of the positive and negative electrode materials based on the balance factor includes: If the measured cycle life of the battery is lower than the preset requirement, a larger balance factor is used as the direction for adjusting the utilization rate and coating density of the positive and negative electrode materials. The utilization rate of the positive and negative electrode materials and the areal density of the corresponding electrode sheets are adjusted and used as new preset parameters. The new preset parameters are re-inputted into the evaluation model to calculate the new balance factor.

[0013] In one possible implementation, when the new balance factor increases, the theoretical energy density of the lithium-ion battery is calculated based on the new preset parameters obtained from the adjustment. When it meets the preset energy density requirements, a battery sample is prepared according to the preset parameters, and the cycle life of the battery sample is tested. When the cycle life does not meet the preset cycle life requirement, repeat the steps of calculating the balance factor and adjusting the preset parameters until the cycle life meets the preset requirement.

[0014] In one possible implementation, the utilization rates of both the positive and negative electrode materials are 80% to 95%, and the areal density of both the positive and negative electrode coatings is 140 to 270 g / m². 2 .

[0015] In one possible implementation, the areal density of both the positive electrode coating and the negative electrode coating is 180~230 g / m². 2 .

[0016] In one possible implementation, prior to the cycle life test step, when the theoretical energy density of the lithium-ion battery calculated based on preset parameters does not meet the preset theoretical energy density requirement: The utilization rate and coating density of the positive electrode material in the positive electrode sheet of the lithium-ion battery, and the utilization rate and coating density of the negative electrode material in the negative electrode sheet are obtained. The utilization rate and coating density of the positive and negative materials are input into the evaluation model to obtain the balance factor. The evaluation model is obtained by fusing the utilization rate and coating density of the positive and negative electrode materials. Based on the balance factor, the adjustment direction of the utilization rate and coating density of the positive and negative electrode materials is determined, the preset parameters are redesigned and the theoretical energy density is recalculated until the theoretical energy density meets the preset requirements.

[0017] In one possible implementation, the negative electrode material is selected from at least one of lithium titanate, titanium oxide, niobium oxide, titanium niobate, niobium titanium oxide, titanium-based composite oxide, and niobium-based composite oxide; the positive electrode material is selected from at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium phosphate with an olivine structure. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0019] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined.

[0020] In lithium-ion battery design, to achieve ultra-long fast-charging cycle life, it's necessary to mitigate structural changes in the positive and negative electrode active materials during cycling. This requires reducing material utilization through voltage control. However, reducing utilization leads to a decrease in specific capacity, thus affecting the battery's energy density. Furthermore, improving the fast-charging capability of lithium-ion batteries generally requires reducing current density. Reducing the areal density of the positive and negative electrode coatings is the most effective method, but this increases the amount of inactive materials (such as current collectors and separators), also reducing energy density. However, battery fast-charging capability and fast-charging cycle life require actual testing, significantly extending the battery development cycle. Therefore, a method is needed to quickly balance the relationship between various design parameters and battery performance to shorten the battery development cycle.

[0021] This invention provides a method for rapidly adjusting the fast-charging cycle life and energy density of a lithium-ion battery, comprising the following steps: Calculate energy density: Based on the preset parameters of the lithium-ion battery, calculate the theoretical energy density of the lithium-ion battery to ensure that it meets the preset energy density requirements; Cycle life testing: Prepare battery samples according to preset parameters and test the cycle life of the battery samples; Calculate the balance factor: When the cycle life does not meet the preset cycle life requirements, obtain the utilization rate and coating density of the positive electrode material in the positive electrode sheet of the lithium-ion battery, and the utilization rate and coating density of the negative electrode material in the negative electrode sheet. Input the utilization rate and coating density of the positive and negative materials into the evaluation model to obtain the balance factor. The evaluation model is obtained by fusing the utilization rate and coating density of the positive and negative electrode materials. Adjusting preset parameters: Based on the balance factor, determine the adjustment direction of the utilization rate and coating density of the positive and negative electrode materials, and redesign the preset parameters; Repeat the steps of calculating energy density, testing cycle life, calculating balance factor, and adjusting preset parameters until the cycle life meets the preset requirements.

[0022] While current development methods for lithium-ion rechargeable batteries generally involve first fabricating a finished battery, then testing its charging speed and cycle life. The test results are then compared to design goals, and discrepancies are identified. Parameter adjustments are made, and another finished battery is fabricated. This process is repeated until a satisfactory battery is obtained. However, when adjusting critical parameters, it's difficult to precisely identify which parameters should be adjusted and how to adjust them to extend cycle life. This can lead to situations where the cycle life of battery samples fabricated with adjusted parameters doesn't significantly improve or even decreases, prolonging the battery development cycle. The purpose of this invention is to provide accurate adjustment directions for critical parameters, ensuring that the cycle life of battery samples fabricated with adjusted parameters significantly improves compared to before adjustment, thereby effectively shortening the overall development cycle.

[0023] The method for rapidly adjusting the fast-charging cycle life and energy density of lithium-ion batteries provided by this invention first involves designing the lithium-ion battery. After determining parameters such as the utilization rate of positive and negative electrode materials, the areal density of the positive and negative electrode coatings, and the mass ratio of inactive components, the theoretical energy density (theoretical energy / theoretical mass) of the designed battery is calculated using software simulation. When the calculated theoretical energy density meets the preset energy density requirements, a battery sample is manufactured according to the current design, and the fast-charging cycle life is tested. When the measured cycle life does not meet the preset cycle life requirements, the utilization rate and areal density of the positive electrode material in the designed positive electrode, as well as the utilization rate and areal density of the negative electrode material in the negative electrode, are input into the evaluation model to calculate the balance factor. By adjusting the magnitude of the balance factor, the adjustment direction of the utilization rate and coating density of the positive and negative electrode materials is determined, thereby achieving rapid adjustment of the battery's fast-charging cycle life and providing guidance for quickly obtaining lithium-ion batteries that meet preset requirements.

[0024] In one possible implementation, the balance factor is calculated as follows: When the cycle life does not meet the preset cycle life requirement, obtain the utilization rate of the positive electrode material in the positive electrode sheet and the areal density of the positive electrode sheet coating, as well as the utilization rate of the negative electrode material in the negative electrode sheet and the areal density of the negative electrode sheet coating. The utilization rates of the positive and negative electrode materials and the areal density of the corresponding electrode sheets are input into the evaluation model to obtain the balance factor. The evaluation model is obtained by weighted fusion of the utilization rates of the positive and negative electrode materials and the areal density of the corresponding electrode sheets.

[0025] In one possible implementation, the evaluation model is obtained by summing the utilization rate of the positive electrode material, the utilization rate of the negative electrode material, the areal density of the positive electrode coating, and the areal density of the negative electrode coating according to a preset ratio.

[0026] By inputting the utilization rates of positive and negative electrode materials and the areal density of the corresponding electrodes into the evaluation model, a balance factor is obtained. The evaluation model integrates the utilization rates of positive and negative electrode materials and the areal density of the corresponding electrodes. The magnitude of the balance factor directly reflects the impact of the utilization rates of positive and negative electrode materials and the areal density of the corresponding electrodes on the cycle life of lithium-ion batteries, thereby quickly determining how to adjust the utilization rates of positive and negative electrode materials and the areal density of the corresponding electrodes.

[0027] In one possible implementation, the evaluation model is as follows:

[0028] Where x is the balance factor, dimensionless; a is the utilization rate of the positive electrode material, in %; b is the utilization rate of the negative electrode material, in %; C a The areal density of the coating on the positive electrode sheet, in g / m². 2 Double-sided; C b The areal density of the negative electrode coating, expressed in g / m³. 2 It is a double-sided structure; both m and n are constants and dimensionless.

[0029] The equilibrium factor in the above evaluation model of this invention is a dimensionless constant, which has no physical meaning in itself, and the above model only uses a, b, and C. a and C b The numerical value of the balance factor is not affected by a, b, and C. a and C b The impact in terms of physical significance.

[0030] Through extensive research into the key design factors related to cycle life and energy density in lithium-ion battery design, the inventors obtained key design parameters (a, b, c) that directly reflect the battery's cycle life and energy density. a and C b The evaluation model of the trend between ) can effectively evaluate the cycle life and energy density of the battery in the early stage of design and quickly determine the direction of adjustment, so as to obtain lithium-ion batteries that meet the requirements of both cycle life and energy density in a shorter period of time.

[0031] In one possible implementation, the size of the constant m is 0.14 to 0.16, and the size of the constant n is 2580 to 2620.

[0032] In one possible implementation, the constant m has a size of 0.15 and the constant n has a size of 2600.

[0033] In one possible implementation, provided that the calculated theoretical energy density meets the preset energy density requirements, the larger the value of the balance factor x, the longer the fast-charging cycle life of the lithium-ion battery; conversely, the smaller the value of the balance factor x, the shorter the fast-charging cycle life of the lithium-ion battery.

[0034] The present invention provides a method for rapidly adjusting the fast-charging cycle life and energy density of lithium-ion batteries. It presents a trend relationship between a balance factor and fast-charging cycle life. When the measured cycle life of a lithium-ion battery does not meet preset requirements, this trend relationship allows for rapid determination of how to adjust the key parameters (a, b, C) of the lithium-ion battery. a and C b Only then can lithium-ion batteries that meet the preset requirements be obtained more quickly.

[0035] In one possible implementation, the adjustment direction of the utilization rate and coating density of the positive and negative electrode materials is determined based on a balance factor, including: If the measured cycle life of the battery is lower than the preset requirement, a larger balance factor is used as the direction for adjusting the utilization rate and coating density of the positive and negative electrode materials. The utilization rate of the positive and negative electrode materials and the areal density of the corresponding electrode sheets are adjusted and used as new preset parameters. The new preset parameters are re-entered into the evaluation model to calculate the new balance factor.

[0036] In one possible implementation, when the new balance factor increases, the theoretical energy density of the lithium-ion battery is calculated based on the new preset parameters obtained from the adjustment. When it meets the preset energy density requirements, prepare battery samples according to preset parameters and test the cycle life of the battery samples; When the cycle life does not meet the preset cycle life requirement, repeat the steps of calculating the balance factor and adjusting the preset parameters until the cycle life meets the preset requirement.

[0037] In one possible implementation, the utilization rates of both the positive and negative electrode materials are 80%–95%, and the areal density of both the positive and negative electrode coatings is 140–270 g / m². 2 .

[0038] In one possible implementation, the areal density of both the positive and negative electrode coatings is 180~230 g / m². 2 .

[0039] In one possible implementation, before the cycle life test step, if the theoretical energy density of the lithium-ion battery calculated based on preset parameters does not meet the preset theoretical energy density requirements: The utilization rate and coating density of the positive electrode material in the positive electrode sheet of the lithium-ion battery, and the utilization rate and coating density of the negative electrode material in the negative electrode sheet are obtained. The utilization rate and coating density of the positive and negative materials are input into the evaluation model to obtain the balance factor. The evaluation model is obtained by fusing the utilization rate and coating density of the positive and negative electrode materials. Based on the balance factor, the adjustment direction of the utilization rate and coating density of the positive and negative electrode materials is determined, the preset parameters are redesigned and the theoretical energy density is recalculated until the theoretical energy density meets the preset requirements.

[0040] Specifically, the larger the calculated balance factor, the lower the theoretical energy density; conversely, the smaller the balance factor, the higher the theoretical energy density. Based on this, the utilization rate of the positive and negative electrode materials and the direction for adjusting the coating density can be quickly determined, thereby obtaining the preset parameters that make the theoretical energy density meet the preset requirements more quickly.

[0041] In one possible implementation, the negative electrode material is selected from at least one of lithium titanate, titanium oxide, niobium oxide, titanium niobate, niobium titanium oxide, titanium-based composite oxide, and niobium-based composite oxide; the positive electrode material is selected from at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium phosphate with an olivine structure.

[0042] The method provided by this invention can be used in lithium-ion batteries where the positive electrode material is a lithium compound, and is particularly suitable for lithium-ion batteries where the negative electrode material is a niobium and / or titanium compound.

[0043] The present invention provides a method for rapidly adjusting the fast-charging cycle life and energy density of lithium-ion batteries. The theoretical energy density is calculated based on preset parameters of the lithium-ion battery. When the theoretical energy density meets the requirements, a battery sample is prepared according to the preset parameters, and the actual cycle life of the sample is tested. When the measured cycle life does not meet the preset requirements, preset key parameters are input into an evaluation model to calculate a balance factor. By adjusting the magnitude of the balance factor, the direction of adjustment for key battery design parameters can be quickly determined. This allows for rapid adjustment of the battery's cycle life and energy density, reducing the number of repeated verifications, significantly saving time in battery preparation and testing, and shortening the development cycle.

[0044] The method for rapidly adjusting the fast-charging cycle life and energy density of lithium-ion batteries provided by this invention can be applied to different types of lithium-ion batteries. The only difference is that the specific evaluation model used is different when the composition and design type of the lithium-ion battery are different.

[0045] The evaluation model provided by this invention is applicable to lithium-ion batteries with the following composition: The negative electrode material is selected from at least one of lithium titanate, titanium oxide, niobium oxide, titanium niobate, niobium titanium oxide, titanium-based composite oxide, and niobium-based composite oxide, or is a mixture of at least one of the above negative electrode materials and other negative electrode materials.

[0046] The cathode material is selected from at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium phosphates with an olivine structure.

[0047] The electrolyte used in lithium-ion batteries consists of lithium salts and organic solvents, wherein the lithium salt anion is selected from F. - Cl - ,Br - I - NO3 - N (CN)2 - BF4 - ClO4 - PF6 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3) 6P - CF3SO3 - CF3CF2SO3 - (CF3SO2)2N - (FSO2)2N - CF3CF2(CF3)2CO -(CF3SO2)2CH - (SF5)3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - At least one of the following; the organic solvent is selected from at least one of fluoroethylene carbonate (FEC), methyl propionate, ethyl propionate, propyl propionate, butyl propionate, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl ethyl carbonate (EMC), methyl propyl carbonate, dipropyl carbonate, dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, vinylene carbonate, sulfolane, γ-butyrolactone, propylene sulfite, and tetrahydrofuran.

[0048] The diaphragm used can be made of a polyolefin-based polymer or a porous nonwoven fabric, wherein the polyolefin-based polymer can be at least one of ethylene homopolymer, propylene homopolymer, ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-methacrylate copolymer, and the porous nonwoven fabric can be high-melting-point glass fiber, polyethylene terephthalate fiber, etc. Additionally, at least one surface of the polyolefin-based polymer or the porous nonwoven fabric may also contain a porous organic / inorganic coating formed by inorganic particles and an adhesive.

[0049] The method provided by the present invention will be verified through specific embodiments below.

[0050] The following embodiments are used to fabricate lithium-ion batteries according to the following steps and the design parameters in Table 1, and the actual energy density and cycle life of the resulting lithium-ion batteries are tested respectively (see Table 1 for details).

[0051] Table 1

[0052] The specific manufacturing steps for the battery design in Table 1 are as follows: 95% of the positive electrode active material, 2% of the conductive agent carbon black, 1% of the conductive agent carbon nanotubes, and 2% of the binder polyvinylidene fluoride are mixed in a certain mass ratio and N-methylpyrrolidone (NMP) solvent is used to prepare the positive electrode slurry by stirring with a planetary mixer. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, dried, rolled and cut to obtain the positive electrode sheet.

[0053] A negative electrode slurry is prepared by mixing 91% of the negative electrode active material, 5% of the conductive agent carbon black, 1% of the conductive agent carbon nanotubes, and 3% of the binder polyvinylidene fluoride in a certain mass ratio and stirring with N-methylpyrrolidone (NMP) solvent using a planetary mixer. The negative electrode slurry is then uniformly coated on both surfaces of the negative electrode current collector aluminum foil, dried, rolled, and cut to obtain the negative electrode sheet.

[0054] The vacuum-dried positive electrode, separator, and negative electrode are stacked in sequence. A polyethylene separator is selected as the separator. The stacked core pack and aluminum-plastic packaging shell are vacuum-dried again, and then the core pack is placed in the aluminum-plastic packaging shell for sealing. The sealed core pack is injected with electrolyte, and after vacuuming, secondary sealing, settling, pre-charging, degassing, formation, and aging processes, a lithium-ion secondary battery with a nominal capacity of 5Ah is produced.

[0055] The prepared batteries were charged at 25°C using a constant current of 1C until the upper limit voltage was reached, then switched to constant voltage charging with a cutoff current of 0.05C. Discharge was then performed at 1C until the lower limit voltage was reached. Discharge capacity and energy data were collected to calculate the battery's energy density (results are shown in Table 1). Fast-charge cycle tests were then conducted on batteries from different embodiments. At 25°C, the batteries were charged at 8C until the upper limit voltage was reached, then allowed to rest for 10 minutes before discharge. Discharge was performed at 8C until the lower limit voltage was reached. The fast-charge cycle life of the batteries was tested, and the number of cycles to approximately 80% capacity retention was taken as the cycle life of the cell (results are shown in Table 1).

[0056] As can be seen from the test results of Examples 1-8 in Table 1, as the value of the balance factor x increases, the energy density of the lithium-ion battery gradually decreases, while the fast-charging cycle life gradually increases. This indicates that the method provided by the present invention can quickly predict the increase or decrease in energy density and cycle life by adjusting the value of the balance factor x, thereby quickly determining the design parameters a, b, and C. a and C b This method provides guidance for battery design by adjusting the direction of battery production, eliminating the need for multiple battery prototypes and tests, thus significantly shortening the development cycle of the target battery. Furthermore, it can quickly identify the main factors affecting battery energy density and fast-charge cycle performance, pinpoint bottlenecks, and predict improvement effects.

[0057] The method provided by this invention is applicable to lithium-ion batteries whose theoretical energy density can be calculated. In practical applications, the theoretical energy density of the battery is pre-calculated using specialized software based on pre-designed parameters. When the theoretical energy density does not meet the preset target, the key design parameters a, b, and c are adjusted according to the trend relationship between the balance factor and energy density (i.e., the larger the balance factor, the lower the energy density of the battery) and the magnitude of the balance factor. a and C b This allows us to predict the trends in energy density and cycle life by observing changes in the magnitude of the newly obtained balance factor. This calculation and adjustment process is repeated until the theoretical energy density and measured cycle life of the lithium-ion battery both meet the preset requirements.

[0058] In practical applications, the theoretical energy density of lithium-ion batteries may differ from the energy density of the actual battery samples. However, this difference does not affect the trend relationship between the balance factor and energy density, and the difference is generally within an acceptable range.

[0059] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for rapidly adjusting the fast-charging cycle life and energy density of a lithium-ion battery, characterized in that, Includes the following steps: Calculate energy density: Based on the preset parameters of the lithium-ion battery, calculate the theoretical energy density of the lithium-ion battery to make it meet the preset energy density requirements; Cycle life test: Prepare battery samples according to the preset parameters and test the cycle life of the battery samples; Calculate the balance factor: When the cycle life does not meet the preset cycle life requirement, obtain the utilization rate and coating density of the positive electrode material in the positive electrode sheet of the lithium-ion battery, and the utilization rate and coating density of the negative electrode material in the negative electrode sheet. Input the utilization rate and coating density of the positive and negative materials into the evaluation model to obtain the balance factor. The evaluation model is obtained by fusing the utilization rate and coating density of the positive and negative electrode materials. Adjusting preset parameters: Based on the balance factor, determine the adjustment direction of the utilization rate and coating density of the positive and negative electrode materials, and redesign the preset parameters; Repeat the steps of calculating energy density, testing cycle life, calculating balance factor, and adjusting preset parameters until the cycle life meets the preset requirements.

2. The method for rapidly adjusting the fast-charging cycle life and energy density of a lithium-ion battery as described in claim 1, characterized in that, The calculation of the balance factor is specifically as follows: When the cycle life does not meet the preset cycle life requirement, the utilization rate of the positive electrode material in the positive electrode sheet and the areal density of the positive electrode sheet coating are obtained, as well as the utilization rate of the negative electrode material in the negative electrode sheet and the areal density of the negative electrode sheet coating are obtained. The utilization rates of the positive and negative electrode materials and the areal density of the corresponding electrode sheets are input into the evaluation model to obtain the balance factor; wherein, the evaluation model is obtained by weighted fusion processing of the utilization rates of the positive and negative electrode materials and the areal density of the corresponding electrode sheets.

3. The method for rapidly adjusting the fast-charging cycle life and energy density of a lithium-ion battery as described in claim 2, characterized in that, The evaluation model is obtained by summing the utilization rate of the positive electrode material, the utilization rate of the negative electrode material, the areal density of the positive electrode coating, and the areal density of the negative electrode coating according to a preset ratio.

4. The method for rapidly adjusting the fast-charging cycle life and energy density of a lithium-ion battery as described in claim 3, characterized in that, The evaluation model is as follows: Where x is the balance factor, dimensionless; a is the utilization rate of the positive electrode material, in %; b is the utilization rate of the negative electrode material, in %; C a The areal density of the coating on the positive electrode sheet, in g / m². 2 Double-sided; C b The areal density of the negative electrode coating, expressed in g / m³. 2 It is a double-sided structure; both m and n are constants and dimensionless.

5. The method for rapidly adjusting the fast-charging cycle life and energy density of a lithium-ion battery as described in claim 4, characterized in that, The constant m has a value of 0.14 to 0.16, and the constant n has a value of 2580 to 2620.

6. The method for rapidly adjusting the fast-charging cycle life and energy density of a lithium-ion battery as described in claim 4, characterized in that, When the calculated theoretical energy density meets the preset energy density requirements, the larger the value of the balance factor x, the longer the fast-charging cycle life of the lithium-ion battery; the smaller the value of the balance factor x, the shorter the fast-charging cycle life of the lithium-ion battery.

7. The method for rapidly adjusting the fast-charging cycle life and energy density of a lithium-ion battery as described in claim 6, characterized in that, The method of determining the adjustment direction of the utilization rate and coating density of the positive and negative electrode materials based on the balance factor includes: If the measured cycle life of the battery is lower than the preset requirement, a larger balance factor is used as the direction for adjusting the utilization rate and coating density of the positive and negative electrode materials. The utilization rate of the positive and negative electrode materials and the areal density of the corresponding electrode sheets are adjusted and used as new preset parameters. The new preset parameters are re-inputted into the evaluation model to calculate the new balance factor.

8. The method for rapidly adjusting the fast-charging cycle life and energy density of a lithium-ion battery as described in claim 7, characterized in that, When the new balance factor increases, the theoretical energy density of the lithium-ion battery is calculated based on the new preset parameters obtained from the adjustment. When it meets the preset energy density requirements, a battery sample is prepared according to the preset parameters, and the cycle life of the battery sample is tested. When the cycle life does not meet the preset cycle life requirement, repeat the steps of calculating the balance factor and adjusting the preset parameters until the cycle life meets the preset requirement.

9. The method for rapidly adjusting the fast-charging cycle life and energy density of a lithium-ion battery as described in claim 1, characterized in that, Before the cycle life test step, if the theoretical energy density of the lithium-ion battery calculated based on the preset parameters of the lithium-ion battery does not meet the preset theoretical energy density requirements: The utilization rate and coating density of the positive electrode material in the positive electrode sheet of the lithium-ion battery, and the utilization rate and coating density of the negative electrode material in the negative electrode sheet are obtained. The utilization rate and coating density of the positive and negative materials are input into the evaluation model to obtain the balance factor. The evaluation model is obtained by fusing the utilization rate and coating density of the positive and negative electrode materials. Based on the balance factor, the adjustment direction of the utilization rate and coating density of the positive and negative electrode materials is determined, the preset parameters are redesigned and the theoretical energy density is recalculated until the theoretical energy density meets the preset requirements.

10. The method for rapidly adjusting the fast-charging cycle life and energy density of a lithium-ion battery as described in claim 1, characterized in that, The negative electrode material is selected from at least one of lithium titanate, titanium oxide, niobium oxide, titanium niobate, niobium titanium oxide, titanium-based composite oxide, and niobium-based composite oxide; the positive electrode material is selected from at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium phosphate with olivine structure.

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