A method for precisely preparing an ultrathin lithium strip for quantitative regulation and a computer device

Abstract

The application discloses a kind of precision preparation method and computer equipment of realizing quantitative control ultra-thin lithium strip, comprising the following steps: S1, the calibration thickness and theoretical laminated thickness of each layer of substrate are obtained;S2, the working parameters of calender roll are obtained;S3, industrial standard model is constructed;S4, the preset speed difference ratio required to achieve the target lithium strip thickness is obtained;S5, quantitative control differential speed calender transfer and winding;S6, when the system needs to replace substrate, whether the constant of the industrial standard model needs to be adjusted according to the grading adaptation rule is judged, and then steps S4-S5 can be executed.The application establishes a thickness prediction model with simple form, clear physical meaning and high precision in all working conditions, realizes accurate presetting and reverse solving of finished lithium strip thickness under different gap, different rolling force and different speed working conditions, the model prediction accuracy is high, and the core pain points of the logical disconnection of core parameters and the failure of cross-working condition in the prior art are completely solved.

Description

Technical Field

[0001] This invention relates to the fields of precision rolling of lithium metal and pre-lithiation of lithium-ion battery anodes, specifically to a method for precision preparation of ultrathin lithium strips with quantitative control and a computer device. Background Technology

[0002] As the energy density requirements of lithium-ion batteries continue to increase, the large-scale application of silicon-based anodes and composite lithium metal anodes is accelerating. However, the irreversible loss of active lithium caused by the formation of the SEI film during the first charge and discharge of the anode material is the core bottleneck limiting the battery's initial efficiency, energy density, and cycle life. The pre-lithiation process, which involves rolling and bonding ultra-thin lithium strips to the anode sheet, has become the mainstream pre-lithiation technology solution in the industry due to its controllable lithium replenishment, ease of operation, and high safety.

[0003] Currently, the industrial production of 0.5-20μm ultrathin lithium strips mainly employs two processes: traditional multi-pass calendering and calendering-transfer. When using the traditional multi-pass calendering method to produce ultrathin lithium strips with a thickness <3μm, the lack of precise control over the roll gap makes the lithium material prone to work hardening, resulting in strip breakage and pinhole defects, with finished product thickness fluctuations generally >±1μm. The calendering-transfer method can only achieve direct composite of lithium foil and electrode sheets, and cannot produce prefabricated ultrathin lithium strips that can be independently stored and transported. Furthermore, the lack of a roll gap pre-control mechanism leads to a high strip breakage rate. Existing linear thickness control models only consider the speed ratio as a single factor, completely ignoring the core influence of calendering gap and rolling force on the plastic flow of lithium material. They also fail to reveal the interactive coupling effect of gap-speed-rolling force, resulting in a complete disconnect between core parameter logic and prediction deviations exceeding 20% ​​across different operating conditions, making them unsuitable for the multi-condition adjustment requirements of industrial applications. Existing technologies lack systematic theoretical guidance for setting core parameters, making it impossible to achieve precise reverse derivation from the "target thickness" to the "gap-rolling force-speed parameter combination." New product transitions require extensive trial-and-error experiments, with first-pass yield rates generally below 70%, resulting in significant material waste. Therefore, a new method for preparing ultrathin lithium strips is urgently needed to address these issues. Summary of the Invention

[0004] This invention addresses at least one technical problem in the prior art by disclosing a precise method and computer equipment for quantitatively controlling the preparation of ultra-thin lithium strips. Based on the quantitative influence of the main effects of rolling gap, speed difference ratio, total rolling force, and the linear interaction effects between multiple parameters on the thickness of the finished product, this invention establishes a simple, physically meaningful, and highly accurate thickness prediction model for all working conditions. This model enables precise pre-setting and reverse solving of the finished lithium strip thickness under different gaps, rolling forces, and speeds. The model boasts high prediction accuracy and completely solves the core pain points of existing technologies, such as logical disconnection of core parameters and failure across working conditions.

[0005] This invention is achieved through the following technical solution:

[0006] This invention first provides a method for precise preparation of ultrathin lithium strips with quantitative control, comprising the following steps:

[0007] S1. Obtain the calibrated thickness of each layer of the substrate and calculate the theoretical stack thickness during the substrate calendering process;

[0008] S2. Based on the theoretical layer thickness, and combining the law of constant volume of metal plastic deformation and the strain constraint mechanism of multilayer film rolling, the working parameters of the calender roll are obtained.

[0009] S3. Based on the working parameters of the calender roll, construct a ternary fully coupled linear regression model that includes calender working gap G, speed difference ratio R, total rolling force P and multi-parameter interaction terms, and obtain an industrial standard model based on the ternary fully coupled thickness prediction model.

[0010] S4. Based on the target lithium strip thickness required for production, and combined with the working parameters of the calendering roll, substitute the parameters into the industrial standard model to perform a reverse solution, and obtain the preset speed difference ratio required to achieve the target lithium strip thickness.

[0011] S5. Based on the total rolling force and the preset speed difference ratio, set the process parameters for preparing ultrathin lithium strips, and quantitatively control the differential rolling transfer and winding according to the GRP multi-parameter collaborative closed-loop adjustment rules.

[0012] S6. When it is necessary to change the system of the substrate, determine whether it is necessary to adjust the constants of the industrial standard model according to the classification and adaptation rules, and then execute steps S4-S5.

[0013] As a further embodiment, step S1 includes:

[0014] S11. Select a composite lithium strip with a substrate as the raw material and a transfer film compatible with the raw material.

[0015] S12. Measure the calibration thickness of the lithium metal layer, substrate film, and transfer film;

[0016] S13. Based on the calibrated thickness of each layer in S12, calculate the theoretical stack thickness during the rolling process. The calculation formula is:

[0017] (1);

[0018] As a further improvement, the composite lithium strip uses a double-layer structure of substrate film + lithium metal layer. The initial thickness of the lithium metal layer is 5-50 μm, the substrate film is a PP / PE / PET release film with a thickness of 20-100 μm and a peel force of 0.5-2.0 N / 25 mm at 180° at room temperature; the transfer film has a thickness of 5-200 μm and is selected from one of the following: bright copper foil, carbon-coated copper foil, aluminum foil, and PET film.

[0019] Preferably, the substrate film is a carbon-coated copper foil with a conductive carbon layer coated on one side.

[0020] As a further embodiment, step S2 includes:

[0021] S21. Based on the law of constant volume during plastic deformation of metals and the theory of bending strain in thin film rolling, calculate the benchmark value of the working gap compensation under the benchmark total rolling force. The calculation formula is:

[0022] (2);

[0023] S22. Determine the comprehensive correction factor for the benchmark value. The calculation formula is:

[0024] , (3;

[0025] in, This is the correction factor for the total rolling force of the calender rolls. This is the substrate film peel force correction factor. The lithium layer calibration thickness correction factor;

[0026] S23. Obtain the unique and optimal actual value of the working gap compensation amount. :

[0027] (4);

[0028] S24. Determine the target thickness of the lithium strip. Process range:

[0029] When the target thickness of the lithium band is <1μm The range is 1-3 μm;

[0030] When the target thickness of the lithium band is 1-5 μm The range is 3-7μm;

[0031] When the target thickness of the lithium strip is >3μm and close to the initial lithium layer thickness of the raw material... The range is 7-10 μm;

[0032] S25. Obtain the working parameters of the calendering roll;

[0033] (1) The working gap of the calendering roll is G.

[0034] ; (5);

[0035] The calendering roll diameter is 150-500mm, the roll surface roughness Ra≤0.02μm, the roll surface parallelism≤±0.5μm, and the roll surface runout≤±0.3μm;

[0036] (2) Total rolling force range of calender rolls: The equipment foundation adaptation range is 1.0-5.0T, and the model calibration and industrial production range is 1.0-2.0T;

[0037] (3) Roll surface temperature control of calendering rolls: Stable control at 20-40℃ through a circulating water cooling / oil cooling system;

[0038] As a further step, the rules for determining the values ​​of the partial coefficients in S22 are as follows:

[0039] Correction factor for total rolling force of rolling rolls : Using the reference total rolling force P=1.6T as the reference value, For every 0.2T increase in P, the value of K1 increases by 0.08, and so on, until P = 2.0T; for every 0.2T decrease in P, the value of K1 decreases by 0.08, and so on, until P = 1.0T.

[0040] Substrate film peel force correction factor : The peeling force P of the substrate at 180° at room temperature 剥 =1.0 N / 25 mm is the reference value. ;P 剥 For every 0.5 N / 25 mm increase in elevation, the value of K2 increases by 0.15, and this increase continues until P... 剥 =2.0N / 25mm, P 剥 For every 0.5 N / 25 mm decrease, the value of K2 decreases by 0.15;

[0041] Lithium layer calibration thickness correction factor When 5μm≤ When the size is ≤10μm, K3=1;

[0042] When 10μm < When ≤20μm, K3=1.25;

[0043] When 20μm < When ≤30μm, K3=1.5;

[0044] When 30μm < When ≤40μm, K3=1.75;

[0045] When 40μm < When the size is ≤50μm, K3=2.

[0046] As a further embodiment, step S3 includes:

[0047] S31. Obtain the measured thickness required for the ternary fully coupled linear regression model through multiple repeated calibration experiments. ;

[0048] S32. For the multiple sets of data points obtained in the experiment (G, R, P, ... A ternary fully coupled thickness prediction model was obtained by performing multiple linear regression fitting; based on the ternary fully coupled thickness prediction model, an industrial standard model was obtained after multiple full factorial experimental data.

[0049] As a further embodiment, step S31 includes:

[0050] Experimental parameters: completely consistent with the basic conditions determined in step S1;

[0051] Experimental environment: completely consistent with the measurement environment in step S1;

[0052] The gradient setting rules for the experiment are as follows: The gradient follows the principle of uniform distribution, with the actual value of the working gap compensation amount used. Centered on the center, uniform values ​​are taken in the upper and lower intervals. At least 5 gradient speed difference ratios R are set under each rolling working gap G gradient, and at least 6 gradient total rolling force P are set under each speed difference ratio gradient.

[0053] Repeatability requirements: Each GRP parameter combination must be performed at least 3 times independently.

[0054] Data Acquisition: After each set of experiments, the actual thickness of the finished lithium strip is measured according to the thickness measurement method in step S12. The arithmetic mean of three repeated experiments is taken as the measured thickness of that parameter combination. .

[0055] As a further embodiment, step S32 includes:

[0056] S321. Organize the data in S31 into "G, R, P, " Standardize the data into a table and remove outliers;

[0057] S322, will Let Y be the response variable, and let G, R, P, R×P, and G×R be continuous independent variables (X) to obtain the ternary fully coupled thickness prediction model:

[0058] (6);

[0059] in, The intercept of the model is dimensionless. The main effect coefficient of the calendering gap G is given in μm. -1 ; The main effect coefficient of the velocity difference ratio R is expressed in μm. The main effect coefficient of the total rolling force P is expressed in μm / T; The interaction coefficient between the speed difference ratio R and the total rolling force P is expressed in μm / T. The interaction coefficient between the calendering gap G and the speed difference ratio R, in μm. -1 ;

[0060] S323. Calculate the average absolute error between the model prediction value and the measured value. When the average absolute error is ≤0.1μm and the maximum relative error is ≤5%, the three-element fully coupled thickness prediction model meets the requirements. Execute step S324. Otherwise, repeat steps S321-S322.

[0061] S324. Based on the aforementioned ternary fully coupled thickness prediction model, and after multiple full-factor experiments, an industry standard model is obtained.

[0062] (7).

[0063] As a further embodiment, step S4 includes:

[0064] S41. Complete the raw material calibration according to steps S1-S2, and determine the optimal value, rolling working gap and total rolling force;

[0065] S42. Substitute the target lithium strip thickness, rolling working gap, and total rolling force into the calibrated industrial standard model and rearrange it into a linear equation in one variable concerning the speed difference ratio.

[0066] S43. Solve the linear equation in one variable to obtain the preset speed difference ratio. ;

[0067] Preferably, the preset speed difference ratio The range is: 0.1-0.9.

[0068] If the preset speed difference ratio If the total rolling force is increased or the rolling gap is decreased, the solution is recalculated until the preset speed difference ratio is reached. The requirements are met;

[0069] If the preset speed difference ratio If the total rolling force is reduced or the rolling gap is increased, the solution is recalculated until the preset speed difference ratio is reached. The requirements are met.

[0070] As a further embodiment, step S5 includes:

[0071] S51. Keep all parameters in steps S1 and S2 unchanged, and set the production process parameters;

[0072] S52. In a drying workshop environment with an ambient dew point ≤ -45℃, the raw material composite lithium strip and the transfer film are aligned and introduced into the calendering roll. Under the combined action of the shearing force generated by the differential speed and the set total rolling force, the metallic lithium layer is precisely peeled off from the substrate film and simultaneously and uniformly bonded to the surface of the transfer film to complete the ultra-thin forming.

[0073] S53. During the production process, the thickness of the finished lithium strip is detected. When the deviation between the measured thickness and the target thickness exceeds the set value, it is adjusted according to the GRP multi-parameter collaborative closed-loop adjustment rule.

[0074] S54. The stripped blank substrate film is wound up and recycled using a constant tension mode, and the transfer film with the ultra-thin lithium tape attached is wound up using a gradient tension mode to obtain the ultra-thin lithium tape finished product.

[0075] As a further solution, the GRP multi-parameter collaborative closed-loop adjustment rule includes:

[0076] Priority adjustment: Speed ​​difference ratio R > Total rolling force P > Rolling working gap G;

[0077] Adjust boundary conditions: The total rolling force P is in the range of 1.0-2.0T, and the rolling gap G must not exceed the actual value of the corresponding gap compensation. Within the feasible range, it is forbidden to adjust the rolling gap G across the range, and the thickness of the finished product shall not be greater than the initial lithium layer thickness of the raw material.

[0078] If the measured thickness is greater than the target thickness: increase the speed difference ratio R, with a single adjustment step size of 0.01-0.05, and after adjustment, run stably for 3-5 roll circumferences before testing again; if the thickness still does not meet the standard, simultaneously fine-tune to increase the total rolling force P, with a single step size of 0.1T, and decrease the rolling working gap G, with a single step size of 0.5μm;

[0079] If the measured thickness is less than the target thickness: reduce the speed difference ratio R, with a single adjustment step size of 0.01-0.05, and after adjustment, run stably for 3-5 roll circumferences before checking again; if the thickness still does not meet the standard, simultaneously fine-tune to reduce the total rolling force P, with a single step size of 0.1T, and increase the rolling working gap G, with a single step size of 0.5μm;

[0080] Recalibration threshold for the industrial standard model: If the deviation of the measured thickness still exceeds ±0.5μm after three consecutive adjustments, production should be stopped immediately, and the calibration experiment and coefficient fitting of the ternary fully coupled thickness prediction model should be carried out again.

[0081] As a further embodiment, step S6 includes:

[0082] S61. Complete the parameter calibration and theoretical stacking thickness calculation of the new raw material system according to step S1, and determine the maximum thickness of the new finished lithium strip.

[0083] S62. Obtain the actual value of the working gap compensation amount and its adaptation range according to step S2.

[0084] S63. Determine whether the constants of the industrial standard model need to be adjusted according to the hierarchical adaptation rules;

[0085] S64. Complete the reverse solution of the target thickness according to step S4, and complete continuous production according to step S5.

[0086] As a further step, the hierarchical adaptation rules include:

[0087] If the transfer film material and thickness are changed, the substrate film and lithium layer thicknesses remain unchanged, and the new rolling gap G value is still within the range of the actual value δ of the working gap compensation amount of the original calibration model, then the industrial standard model described in S3 can be used directly without re-experimentation.

[0088] If the substrate film is changed or the lithium layer thickness is altered, the calibration experiment and coefficient fitting of the ternary fully coupled thickness prediction model must be completed again according to S3 to obtain a new industry standard model.

[0089] The present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described.

[0090] The features and beneficial effects of this invention are as follows:

[0091] (1) This invention establishes a full-process collaborative control system based on a three-dimensional fully coupled linear regression model of working gap-differential speed-pressure, which completely overturns the traditional single-variable experience trial and error mode of the process. The core is divided into two closed-loop stages: the first stage, through the compensation amount of working gap. The theoretical formula calculation and multi-factor working condition correction are used to accurately set the working gap G of the calendering roll, providing a stable and controllable low-stress plastic deformation environment for the peeling and transfer of lithium strip. This fundamentally solves the problems of strip breakage and substrate wrinkling in the ultra-thinning process, ensuring the integrity of lithium strip forming and providing a stable and repeatable process basis for subsequent quantitative models. The second stage: Through a ternary fully coupled linear regression model with G coupling, the main effects of calendering working gap G, speed difference ratio R, and total rolling force P, as well as the linear interaction effects between multiple parameters, on the finished product thickness are revealed. A simple, physically meaningful, and highly accurate ternary fully coupled thickness prediction model is established, realizing the accurate preset and reverse solution of the finished lithium strip thickness under different gaps, different rolling forces, and different speeds. This completely solves the core pain points of existing models, such as logical disconnection of core parameters and failure across working conditions.

[0092] (2) This invention can be directly adapted to existing roll-to-roll calendering production lines without large-scale equipment modification. Only the servo control system and online thickness measurement module need to be upgraded to achieve industrial application. The model is simple and can be directly integrated into the production line PLC / DCS control system to achieve fully automatic parameter calculation and closed-loop control. The model covers the gap, rolling force and speed range commonly used in industrial production, and is compatible with various raw material systems and transfer film types. It can cover the production of lithium strips of all specifications from 0.5 to 20 μm and is compatible with the pre-lithiation requirements of different battery systems.

[0093] (3) Through the full-process GRP multi-parameter collaborative control and quantitative closed-loop adjustment rules, the standard deviation of the thickness fluctuation of the finished lithium strip can be stably controlled within ±0.3μm, which is far superior to the industry level of ±1μm or more of the traditional process; it can achieve continuous industrial production for more than 24 hours without significant thickness drift and significantly improve batch consistency. Attached Figure Description

[0094] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0095] Figure 1 This is a flowchart of the method for precise preparation of ultrathin lithium strips with quantitative control, as described in an embodiment of the present invention. Detailed Implementation

[0096] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below, and embodiments of the present invention will be provided, but this does not limit the scope of the present invention.

[0097] For ease of expression and understanding, this application adopts uniform symbols and terminology definitions, as detailed in Table 1.

[0098] Table 1

[0099]

[0100] A method for precise preparation of ultrathin lithium strips with quantitative control, such as Figure 1 As shown, it includes the following steps:

[0101] S1. Substrate pretreatment and parameter calibration, including the following steps:

[0102] S11. Select a composite lithium strip with a substrate as the raw material, and select a suitable transfer film.

[0103] In some embodiments, the composite lithium strip is made of a substrate film + lithium metal layer bilayer structure, wherein the initial thickness of the lithium metal layer is 5-50 μm, the substrate film is a PP / PE / PET release film with a thickness of 20-100 μm and a peel force of 0.5-2.0 N / 25 mm at 180° (standard test angle for reverse flat tear) at room temperature; the transfer film is selected with a thickness of 5-200 μm and can be selected from one of the following: bright copper foil, carbon-coated copper foil, aluminum foil, and PET film.

[0104] Preferably, the substrate film is a carbon-coated copper foil with a conductive carbon layer coated on one side (copper foil substrate thickness 6-12μm, conductive carbon layer thickness 0.5-2μm, surface roughness Ra 0.2-0.6μm).

[0105] S12. Measure the calibration thickness;

[0106] A high-precision non-contact laser thickness gauge was used in a dry workshop environment with an ambient dew point ≤-45℃ and an ambient temperature stably controlled at 23±2℃. One measurement point was set every 5mm along the transverse direction of the sample, with no less than 20 effective measurement points per sample. The sampling frequency was ≥100Hz, and the arithmetic mean of all effective measurement points was taken as the calibrated thickness of the corresponding layer.

[0107] Preferably, the measurement accuracy of the non-contact laser thickness gauge is ≤ ±0.05μm.

[0108] The non-contact laser thickness gauge has a measurement accuracy of ≤±0.05μm. Measurement accuracy is guaranteed from the perspective of the measurement equipment. In a dry workshop environment with a dew point ≤-45℃ and a stable temperature control of 23±2℃, the measurement accuracy is effectively avoided due to lithium oxidation and thermal expansion. The measurement environment provides dual protection for measurement accuracy. Multiple measurement points are used to ensure accuracy from the sampling method perspective, and the calibrated thickness is obtained through an arithmetic average, ensuring accuracy from the calculation method perspective. This method designs the calibrated thickness accuracy from four aspects: measurement equipment, measurement environment, sampling method, and calculation rules, effectively guaranteeing the precision of the calibrated thickness.

[0109] S13. Based on the calibrated thickness of each layer in S12, calculate the theoretical stack thickness during the rolling process. The calculation formula is:

[0110] (1);

[0111] S2. The theoretical stack thickness calculated based on step S1 By combining the law of constant volume during plastic deformation of metals with the strain constraint mechanism of multilayer film rolling, the working parameters of the calender roll are obtained; the specific steps are as follows:

[0112] S21. Based on the law of constant volume during plastic deformation of metals and the theory of bending strain in thin film rolling, calculate the benchmark value of the working gap compensation under the benchmark total rolling force (P=1.0T). The calculation formula is:

[0113] (2);

[0114] The formula is calculated to obtain This serves as the optimal compensation benchmark for the corresponding raw material system under baseline operating conditions and is the core basis for setting fixed parameters for industrial mass production.

[0115] S22. Since the benchmark value may contain errors during the calculation process, it is necessary to determine the comprehensive correction factor based on the actual rolling conditions and raw material characteristics. The calculation formula is:

[0116] , (3;

[0117] in, This is the correction factor for the total rolling force of the calender rolls. This is the substrate film peel force correction factor. The thickness correction factor is used to calibrate the lithium layer.

[0118] The rules for determining the values ​​of each component coefficient are as follows:

[0119] Correction factor for total rolling force of rolling rolls : Using the reference total rolling force P=1.6T as the reference value, For every 0.2T increase in the target total rolling force P relative to the reference value of 1.6T, the coefficient K1 increases by 0.08. Conversely, for every 0.2T decrease in the target total rolling force P relative to the reference value of 1.6T, the coefficient K1 decreases by 0.08. The specific proportional relationship is as follows:

[0120] Correction factor for total rolling force of rolling rolls Using a reference total rolling force P=1.6T as the baseline value, the specific proportional relationship is as follows:

[0121] Reference point: P = 1.6T → K1 = Reference value;

[0122] P increases to 1.8T (an increase of 0.2T) → K1 = baseline value + 0.08;

[0123] P increases to 2.0T (then increases by 0.2T) → K1 = baseline value + 0.16;

[0124] Incrementing sequentially until P = 2.0T;

[0125] P drops to 1.4T (a decrease of 0.2T) → K1 = baseline value - 0.08;

[0126] P drops to 1.2T (then drops by another 0.2T) → K1 = baseline value - 0.16;

[0127] Decrease sequentially until P = 1.0T;

[0128] Substrate film peel force correction factor : The peeling force P of the substrate at 180° at room temperature 剥 =1.0 N / 25 mm is the reference value. The specific proportional relationship is as follows:

[0129] Benchmark: P 剥 = 1.0 N / 25 mm → K2 = reference value;

[0130] P 剥 Increase to 1.5 N / 25 mm (increase by 0.5 N / 25 mm) → K2 = reference value + 0.15;

[0131] P 剥 Increase to 2.0 N / 25 mm (then increase by 0.5 N / 25 mm) → K2 = reference value + 0.30;

[0132] Incrementing sequentially until P 剥 =2.0N / 25mm;

[0133] P 剥 Reduce to 0.5 N / 25 mm (reduction of 0.5 N / 25 mm) → K2 = baseline value - 0.15;

[0134] Lithium layer calibration thickness correction factor :

[0135] When 5μm≤ When the size is ≤10μm, K3=1;

[0136] When 10μm < When ≤20μm, K3=1.25;

[0137] When 20μm < When ≤30μm, K3=1.5;

[0138] When 30μm < When ≤40μm, K3=1.75;

[0139] When 40μm < When the size is ≤50μm, K3=2.

[0140] S23. For continuous mass production with fixed raw materials and fixed operating conditions, multiply the benchmark value by the comprehensive correction coefficient to obtain the unique and optimal actual value of the working gap compensation:

[0141] (4);

[0142] After the raw materials and target rolling force P are fixed, the The value is a unique, optimal, fixed value, corresponding to a unique calendering gap G. It serves as the benchmark parameter for the entire mass production process and is not adjusted unless there are special circumstances, thus ensuring the stability and consistency of the mass production process.

[0143] S24. Determined based on experience values ​​from production experience. The feasible range for the entire process is 1-10μm. Defects such as roller sticking, strip breakage, substrate wrinkling, and insufficient peeling may occur outside this range. In industrial production, the thickness of the lithium strip can be selected according to the following rules based on the target lithium strip thickness. The initial values ​​are chosen to ensure process feasibility and molding stability:

[0144] When the target thickness of the lithium band is <1μm Prioritize the 1-3μm range to ensure molding stability during extreme thinning;

[0145] When the target thickness of the lithium band is 1-5 μm Prioritize the 3-7μm range to ensure accuracy and consistency in mass production;

[0146] When the target thickness of the lithium strip is >3μm and close to the initial lithium layer thickness of the raw material... Prioritize the 7-10μm range to reduce lithium material processing stress and avoid work hardening and band breakage.

[0147] Once the target thickness is determined, The initial value can be calculated using the formula in this step. If the calculated value exceeds the corresponding range mentioned above, it can be fine-tuned within the range. Value, to ensure the feasibility of the process.

[0148] S25. Obtain the working parameters of the calendering roll;

[0149] (1) The working gap of the calendering roll is G.

[0150] ; (5);

[0151] The calendering roll diameter is 150-500mm, the roll surface roughness Ra≤0.02μm, the roll surface parallelism≤±0.5μm, and the roll surface runout≤±0.3μm;

[0152] (2) Total rolling force range of calender rolls: The equipment foundation adaptation range is 1.0-5.0T, and the model calibration and industrial production optimization range is 1.0-2.0T. The correction range of the coefficients is perfectly matched;

[0153] (3) Roll surface temperature control of calendering roll: The temperature is stably controlled at 20-40℃ through a circulating water cooling / oil cooling system to avoid lithium metal sticking to the roll and work hardening and breakage.

[0154] This application achieves precise setting of the rolling working gap G through "quantitative calculation and multi-factor correction of the working gap compensation δ". It clearly distinguishes the different application rules between the fixed value in mass production and the gradient value in model calibration, and provides clear guidance for industrial value selection, ensuring low-stress forming of lithium strips and fundamentally solving the problems of strip breakage and substrate wrinkling in the ultra-thinning process. It realizes a fully parameter-coupled closed loop, completely solving logic breaks and core industry bottlenecks.

[0155] S3. Based on the rolling gap G determined in step S2, construct a ternary fully coupled linear regression model (ternary refers to three independent variables: G, R, and P) that includes the rolling gap G, speed difference ratio R, total rolling force P, and multiple parameter interaction terms. Complete the model calibration and inverse solution of the target thickness. The specific process is as follows:

[0156] S31. Obtain the measured thickness required for the ternary fully coupled linear regression model through multiple repeated calibration experiments. ,

[0157] Experimental parameters: Keep the basic conditions, such as the raw material system, roller surface temperature, and equipment parameters determined in step S1, unchanged.

[0158] Experimental environment: completely consistent with the measurement environment in step S1, i.e., a dry workshop environment with an ambient dew point ≤ -45℃ and an ambient temperature of 23±2℃;

[0159] Gradient setting rules for the experiment: To fit the main effect and interaction effect of the calendering gap G on the finished product thickness, at least three gradient δ values ​​must be set within the process-feasible range of 1-10 μm, covering the range of δ values ​​commonly used in industrial production; the gradient setting must follow the principle of uniform distribution, using the baseline value as a reference. Centered on ×K, values ​​are uniformly selected in the upper and lower intervals. At least 5 gradient speed difference ratios R (range 0.1-0.9) are set under each G gradient, and at least 6 gradient total rolling forces P (range 1.0-2.0T) are set under each speed difference ratio gradient.

[0160] Repeatability requirements: Each GRP parameter combination must be performed at least 3 times independently.

[0161] Data Acquisition: After each set of experiments, the actual thickness of the finished lithium strip was measured according to the thickness measurement method in step S1. The arithmetic mean of three repeated experiments was taken as the measured thickness of that parameter combination. .

[0162] S32. For the multiple sets of data points obtained in the experiment (G, R, P, ... A ternary fully coupled thickness prediction model was obtained by performing multiple linear regression fitting. The specific method is as follows:

[0163] S321. Take the arithmetic mean of the measured thicknesses from all repeated experiments in S31, and organize them into "G, R, P, The data was standardized into a table. Outliers were removed using the Grubbs test (significance level α = 0.05). The specific rules were as follows: The Grubbs statistic G_stat was calculated for each group of three repeated experiments. If G_stat was greater than α = 0.05 and the corresponding Grubbs critical value for the sample size (the critical value was taken from the Grubbs critical value table in the national standard GB / T 4883-2008 "Statistical Processing and Interpretation of Data - Judgment and Handling of Outliers in Normal Samples"), the outlier data point was removed. After removing outliers from a single group of experiments, one additional independent repeated experiment was required to ensure that the effective repeated experimental data for that group was no less than three groups. After removing outliers within all data groups, the Grubbs test was performed again on the overall dataset. After removing overall outliers, no additional experiments were needed, and the dataset was directly used for fitting.

[0164] S322, a multiple linear regression fitting module using Minitab 21, IBM SPSS Statistics 26, or Matlab R2023b software.

[0165] In some embodiments, the present invention preferentially uses Minitab 21 software for multiple linear regression fitting. The Minitab 21 software is opened, the standardized data table is imported, and then clicks Statistics → Regression → Regression → Fit Regression Model. Set Y as the response variable and G, R, P, R×P, and G×R as continuous independent variables (X). Perform multiple linear regression fitting. Output the fitted values ​​and significance p-values ​​for each constant. Retain significant parameters with p < 0.05, remove insignificant parameters, and refit to ensure the statistical validity of the model, thus obtaining the ternary fully coupled thickness prediction model:

[0166] (6);

[0167] in, The intercept of the model is dimensionless. The main effect coefficient of the calendering gap G is given in μm. -1 ; The main effect coefficient of the velocity difference ratio R is expressed in μm. The main effect coefficient of the total rolling force P is expressed in μm / T; The interaction coefficient between the speed difference ratio R and the total rolling force P is expressed in μm / T. The interaction coefficient between the calendering gap G and the speed difference ratio R, in μm. -1 Model fit requirements To ensure the accuracy of predictions under all operating conditions.

[0168] The model shows that the rolling gap G directly determines the length of the plastic deformation zone of the lithium material within the roll gap, the contact pressure distribution, and the shear force transmission efficiency, making it a core independent variable affecting the lithium layer peeling and transfer rate and the final thinning thickness. The speed difference ratio R determines the magnitude of the shear force; the smaller R is, the stronger the differential shear force, the greater the lithium layer thinning, and the smaller the finished product thickness. The total rolling force P determines the interface contact state; the larger P is, the stronger the bonding force between the lithium layer and the transfer film, and the more complete the peeling and transfer. These three factors exhibit a significant linear interaction effect. The finished lithium strip thickness strictly meets the requirements... The physical constraints conform to the law of constant volume during plastic deformation of metals. After the raw materials are selected For a fixed value, G and It is a unique mapping relationship with a one-to-one linear correspondence.

[0169] S323. Calculate the average absolute error between the model's predicted values ​​and the measured values. The average absolute error should be ≤0.1μm and the maximum relative error should be ≤5%. If the accuracy requirements are not met, supplement the experimental data points to increase the sample size and then refit the model.

[0170] S324. Based on the aforementioned ternary fully coupled thickness prediction model, an industry standard model is obtained;

[0171] After multiple full-factor experiments, the model intercept and the values ​​of each coefficient were obtained. =-2.866, b=0.02869, c=3.412, d= ,e= f= Substituting this data into the ternary fully coupled thickness prediction model, we obtain the industry standard model:

[0172] (7);

[0173] Model fit With an average prediction error of ≤0.06μm, it covers the full range of 0.3-5μm ultrathin lithium strip production and can be directly used for industrial production line parameter preset.

[0174] The industry standard model is adapted for G=68-77μm, corresponding to =1-10μm, R=0.1-0.9, P=1.0-2.0T. Models exceeding this range require recalibration. Models can only be used within the corresponding calibration range. It can be used within the feasible range and cannot be used across different ranges; the thickness of the finished product must not exceed the initial lithium layer thickness of the raw material by 5μm.

[0175] This application, through a ternary fully coupled thickness prediction model with G coupling, for the first time incorporates the actual rolling gap G in production into the core thickness control system. It reveals the influence of the main effects of G, speed difference ratio R, and total rolling force P, as well as the multi-parameter interactive coupling effect on thickness. It solves the core pain points of existing models, such as the disconnection of core parameters and failure across working conditions. It can stably prepare ultra-thin lithium strips from 0.5μm to the initial thickness of the raw material based on the initial lithium layer thickness of the raw material, and cover the full industrial specifications of 0.5-20μm by changing the raw material. An industrial standard model is obtained through a ternary fully coupled thickness prediction model. The compensation amount for working gap is accurately determined through theoretical formulas and multi-factor working condition corrections. A complete system of benchmark values, correction rules, feasible ranges, and value guidance is clearly defined, without reliance on experience. The goodness of fit of the multivariate thickness prediction model is ≥0.998, and the average prediction error is ≤0.06μm. It can directly solve the unique optimal combination of process parameters for any target thickness that meets physical constraints, any gap, and any suitable rolling force working condition. This increases the first-time material feeding success rate of new product conversion and working condition adjustment to over 98%, shortens the conversion cycle from hours to minutes, and significantly reduces trial and error costs and material waste.

[0176] S4. Solve in reverse based on the target thickness: Based on the target lithium strip thickness required for production... (Strictly required) Combining the rolling gap G determined in step S2 and the total rolling force P adapted to the production line, the inverse function of the above fitting model is substituted to obtain the precise preset speed difference ratio required to achieve the target thickness. Specific methods include:

[0177] S41. Complete the raw material calibration according to S1-S2, optimal. Value calculation, setting of rolling gap G, determination of total rolling force P and other prerequisite parameters;

[0178] S42, will Substituting G and P into the calibrated industrial standard model, we can compose a linear equation in one variable R.

[0179] S43. Solve the linear equation in one variable to obtain... ;

[0180] S44, if For values ​​outside the 0.1-0.9 range, adjustments will be made according to the following rules:

[0181] like Prioritize increasing the total rolling force P or decreasing the rolling gap G, then recalculate until... The requirements are met;

[0182] like Prioritize reducing the total rolling force P or increasing the rolling gap G, then recalculate until... The requirements are met.

[0183] This invention solves the problem of poor process controllability by reversing the target thickness to process parameters in one click, while ensuring that the first-time material feeding qualification rate of new products is increased to over 98%.

[0184] Example of this step:

[0185] To produce target thickness (For raw materials with a thickness of ≤5μm, taking the total rolling force P=1.5T pre-selected based on the production line conditions, and assuming that the substrate peeling force and lithium layer thickness meet the benchmark values, the specific operating procedure is as follows:

[0186] X1. Calculation of reference value and correction factor: Calculated according to formula S2, under the reference total rolling force. ; Selecting P=1.5T, which is 0.1T lower than the baseline value, corresponds to The substrate peel strength and lithium layer thickness both meet the benchmark values. , Comprehensive correction coefficient ;

[0187] X2, Finally, G was determined: the optimal mass production value was obtained through calculation. value,

[0188] Corresponding to the calendering working gap ;

[0189] X3. Substitute into the industry standard model to solve:

[0190] ;

[0191] X4. Equation simplification and solution:

[0192] First step, calculate the constant term: ;

[0193] The second step is to calculate the consolidation coefficients of R: ;

[0194] The third step is to rearrange the equation into a linear equation in one variable: ;

[0195] Step 4: Rearrange terms and solve: The feasible solution is obtained by solving the problem. It falls within the applicable range of 0.1-0.9 and requires no adjustment;

[0196] X5. Process Verification: Based on the solution... By setting the linear speed of the back support roller and the working roller, an ultra-thin lithium strip of the target thickness can be formed in one step, with the measured thickness deviating from the target thickness by ≤0.5%.

[0197] S5. Based on the P obtained in step S4, The process parameters were set to complete the continuous preparation of ultrathin lithium strips. At the same time, the GRP multi-parameter synergistic closed-loop adjustment rules were clarified to quantitatively control differential rolling transfer and winding.

[0198] S51. Set process parameters: Keep all parameters from steps S1 and S2 unchanged, and set the total rolling force of the rolling mechanism according to the solved total rolling force P. The linear speeds of the back support roller and the working roller are set separately, with the basic linear speed of the working roller being 1-50 m / min. High-frequency tension sensors with a sampling frequency of ≥1000 Hz are installed in all unwinding, calendering, and winding stages throughout the entire process, and the running tension fluctuations of the raw material and transfer film are controlled within ±0.5 N.

[0199] S52. In a drying workshop environment with an ambient dew point ≤ -45℃, the raw material composite lithium strip and transfer film are aligned and fed into the calendering roller. Under the combined action of the shearing force generated by the differential speed and the set total rolling force, the metallic lithium layer is precisely peeled off from the substrate film and simultaneously and uniformly bonded to the surface of the transfer film to complete the ultra-thin forming.

[0200] S53. During continuous production, the thickness of the finished lithium strip is detected in real time by an online laser thickness gauge with a detection frequency of ≥10Hz. When the deviation between the measured thickness at three consecutive detection points and the target thickness exceeds ±0.2μm, the thickness is adjusted according to the GRP multi-parameter collaborative closed-loop adjustment rule to ensure that the thickness quickly returns to the target range without the risk of continuous drift.

[0201] The GRP multi-parameter collaborative closed-loop adjustment rules include:

[0202] Priority adjustment: Speed ​​difference ratio R > Total rolling force P > Rolling working gap G;

[0203] Adjust boundary conditions: The total rolling force P shall not exceed the range of 1.0-2.0T, and the rolling gap G shall not exceed the corresponding... The feasible range is defined, and adjustments to G across ranges are prohibited; the thickness of the finished product must not exceed the upper limit of the initial lithium layer thickness of the raw material.

[0204] If the measured thickness is greater than the target thickness: prioritize increasing the speed difference ratio R (increasing R enhances the differential shear force, resulting in a larger reduction in lithium layer thickness and a decrease in overall thickness), with a single adjustment step size of 0.01-0.05. After adjustment, run the system stably for 3-5 roll circumferences and then test again. If the thickness still does not meet the standard, simultaneously fine-tune the system by increasing the total rolling force P (single step size 0.1T) and decreasing the rolling working gap G (single step size 0.5μm).

[0205] If the measured thickness is less than the target thickness: prioritize reducing the speed difference ratio R (reducing R weakens the differential shear force, reduces the lithium layer thinning rate, and increases the thickness), with a single adjustment step size of 0.01-0.05. After adjustment, run stably for 3-5 roll circumferences and then test again; if the thickness still does not meet the standard, simultaneously fine-tune to reduce the total rolling force P (single step size 0.1T) and increase the rolling working gap G (single step size 0.5μm).

[0206] Recalibration threshold for the industrial standard model: If the thickness deviation still exceeds ±0.5μm after three consecutive adjustments, production should be stopped immediately, and the calibration experiment and coefficient fitting of the ternary fully coupled thickness prediction model should be completed again according to the requirements of S3.

[0207] This invention solves the problems of disconnection between the rolling gap parameters and the thickness control model logic in the prior art, and the problem of cyclical verification. It establishes a thickness control system that is fully coupled with gap, speed and rolling force, and realizes a closed loop of the whole process from theoretical calculation to equipment execution. It also establishes a quantitative multi-parameter collaborative closed loop adjustment rule to achieve long-term stable production and control the standard deviation of finished product thickness fluctuation within ±0.2μm.

[0208] S54. The stripped blank substrate film is wound up and recycled using a constant tension mode, with the winding tension controlled at 1-30N. The transfer film with the ultra-thin lithium strip attached is wound up using a gradient tension mode after online defect detection (the tension decreases linearly from the inside to the outside, with a reduction ratio of 5%-10% for every 100m of roll length, and the initial tension controlled at 2-4N) to obtain the ultra-thin lithium strip product.

[0209] This invention achieves stable control of the standard deviation of finished lithium strip thickness fluctuation within ±0.3μm through full-process GRP multi-parameter collaborative control and quantitative closed-loop adjustment rules, which is far superior to the industry level of ±1μm or more of traditional processes; it can achieve continuous industrial production for more than 24 hours without significant thickness drift and significantly improve batch consistency.

[0210] S6. Raw material system replacement and adaptation method:

[0211] S61. Complete the parameter calibration and theoretical layer thickness calculation of the new raw material system according to S1, and determine the upper limit of the maximum thickness of the new finished lithium strip (i.e., the initial lithium layer thickness of the new raw material). );

[0212] S62. Calculate the δ baseline value of the new system, determine the comprehensive correction coefficient, and adapt the optimal δ value to the feasible range according to S2.

[0213] S63, Hierarchical Adaptation Rules:

[0214] Scenario 1: Only the transfer film material and thickness are changed, while the substrate film and lithium layer thicknesses remain unchanged, and the new G value is still within the δ feasible range of the original calibration model: the original calibration model can be used directly without repeating the experiment;

[0215] Scenario 2: When changing the thickness of the substrate film or lithium layer, the full factorial calibration experiment and model constant fitting of the new system must be completed according to S3;

[0216] S64. Complete the reverse solution of the target thickness according to S3 (the target thickness must be ≤ the thickness of the new raw material lithium layer), and complete the continuous production according to S5.

[0217] This method can be directly adapted to existing roll-to-roll calendering production lines without large-scale equipment modifications. Only the upgrade of the servo control system and online thickness measurement module is required for industrial application. The model is simple in form and can be directly integrated into the production line PLC / DCS control system to achieve fully automatic parameter calculation and closed-loop control. The model covers the gap, rolling force, and speed range commonly used in industrial production, is compatible with various raw material systems and transfer film types, and can cover the production of lithium strips of all specifications from 0.5 to 20 μm, adapting to the pre-lithiation requirements of different battery systems.

[0218] This invention overcomes the limitations of existing technologies by establishing a full-process collaborative control system based on a three-dimensional fully coupled linear regression model of working gap, differential speed, and pressure. This completely overturns the traditional single-variable, experience-based trial-and-error model. The core consists of two closed-loop stages: the first stage involves compensating for the working gap... The theoretical formula calculation and multi-factor working condition correction are used to accurately set the working gap G of the calendering roll, providing a stable and controllable low-stress plastic deformation environment for the peeling and transfer of lithium strip. This fundamentally solves the problems of strip breakage and substrate wrinkling in the ultra-thinning process, ensuring the integrity of lithium strip forming and providing a stable and repeatable process basis for subsequent quantitative models. The second stage: Through a ternary fully coupled linear regression model with G coupling, the main effects of calendering working gap G, speed difference ratio R, and total rolling force P, as well as the linear interaction effects between multiple parameters, on the finished product thickness are revealed. A simple, physically meaningful, and highly accurate ternary fully coupled thickness prediction model is established, realizing the accurate preset and reverse solution of the finished lithium strip thickness under different gaps, different rolling forces, and different speeds. This completely solves the core pain points of existing models, such as logical disconnection of core parameters and failure across working conditions.

[0219] This invention enables precise pre-setting and one-time molding of ultra-thin lithium strips with thicknesses ranging from 0.5μm to the initial lithium layer thickness of the raw material under all working conditions. By changing the raw material lithium strips with different initial thicknesses, it can cover the full range of industrial specifications from 0.5 to 20μm, and is widely applicable to the pre-lithiation industrial continuous production of consumer electronics batteries, power batteries, and energy storage batteries.

[0220] Example 1

[0221] The calendering roll has a diameter of 300mm, an effective roll surface width of 400mm, a surface roughness Ra=0.01μm, a roll surface parallelism of ±0.3μm, and a roll surface runout of ±0.2μm. The experimental environment was a drying workshop with an ambient dew point ≤-45℃ and an ambient temperature of 23±2℃. The thickness measurement method was completely consistent with S1, and the thickness of the finished lithium strip was the single-layer thickness of the metallic lithium layer, strictly meeting the physical constraint of ≤ the initial lithium layer thickness of the raw material. The specific steps include the following:

[0222] A1. Substrate Pretreatment and Parameter Calibration: A 5μm thick lithium metal strip attached to a 50μm thick PET substrate film was selected as the raw material. The peel force of the substrate film at 180° (the standard test angle for reverse flat tearing) was 1.0N / 25mm. A 12μm thick smooth copper foil was selected as the transfer film. The thickness was calibrated according to the measurement method in S1, and the theoretical laminate thickness was calculated. The maximum thickness of the finished lithium strip is 5μm.

[0223] A2. Setting up the calendering workshop:

[0224] Calculation of the benchmark value: According to the calculation formula of S2 of the present invention, the benchmark value of the working gap compensation of the raw material system under the benchmark working condition (total rolling force P=1.0T) is as follows: The comprehensive correction factor is determined as follows: the reference total rolling force P = 1.0T. Substrate peel force: 1.0 N / 25 mm Lithium layer thickness ≤ 5μm ≤ 10μm Comprehensive correction coefficient The optimal industrial mass production under the corresponding benchmark operating conditions The value is 5μm.

[0225] Setting the model calibration gradient: To fit the main effect and interaction effect of the calendering gap G on the finished product thickness, a ternary coupling model applicable to all working conditions is established. Within the feasible process range of 1-10μm specified in this invention, three uniformly distributed gradients of 3μm, 5μm, and 7μm are set with the reference value of 5μm as the center. The gradients correspond to calendering gaps G of 70μm, 72μm, and 74μm, respectively, all of which meet the process requirements and cover the range of δ values ​​commonly used in industrial production.

[0226] Set the rolling parameters: The optimal range for the total rolling force model calibration is 1.0-2.0T, and the roll surface temperature is controlled at 25±2℃ by circulating water cooling.

[0227] A3. Model calibration experiment and constant fitting:

[0228] Experimental Design: Keeping all the above basic parameters constant, five speed difference ratios R were set for each G gradient: 0.1, 0.3, 0.5, 0.7, and 0.9. Six total rolling forces P were set for each R gradient: 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0. Each GRP parameter combination was repeated three times. The average thickness of the finished lithium strip was measured using the method in S1, resulting in 90 sets of valid experimental data, as shown in Table 2 below.

[0229] Table 2

[0230]

[0231]

[0232]

[0233]

[0234] The average of all repeated experimental data was taken, and two outlier data sets were removed using the Grubbs' test (α=0.05). After adding two more repeated experimental sets, 90 standardized data sets were obtained. The multiple linear regression module of Minitab 21 software was used to... Set G, R, P, R×P, and G×R as the response variables, and perform fitting.

[0235] The industry standard model is as follows:

[0236] ;

[0237] Model fit All parameters showed significance values ​​of <0.05, and the average prediction error was ≤0.06μm, fully meeting the accuracy requirements of S3.

[0238] A4. Using the above model, prepare an ultrathin lithium strip with a target thickness of 2.0 μm;

[0239] A41. Target Thickness and Operating Condition Settings: Production Target Thickness For ultra-thin lithium strips with a thickness of ≤5μm (upper limit of raw material), the total rolling force P=1.5T was selected based on the production line conditions;

[0240] A42. Determination of S1-S2 parameters: All raw materials and basic parameters are completely consistent with those in Example 1. S2 calculation determines the optimal mass production. =6μm, corresponding to a calendering working gap G=73μm and a roll surface temperature of 25℃;

[0241] A43, S3 Reverse Solution: Substitute the target thickness, G, and P into the standard model established in Example 1 to obtain the solution. ;

[0242] A44. Process Execution: Set the working roller linear speed to 5.0 m / min, according to... The calculated linear speed of the back support roller is 1.055 m / min; the equipment is started for continuous production under a protective atmosphere.

[0243] Results Verification: Measured using method S1, the preset target average thickness of the finished lithium strip was 2.01 μm, with a standard deviation of 0.086 μm. Sampling was conducted after 2 hours of continuous production, and the thickness data from these samples are shown in Table 3 below.

[0244] Table 3

[0245]

[0246] According to the statistical results, the average actual thickness of the samples from continuous production was 2.016 μm, and the standard deviation was 0.086 μm. The actual thickness deviated from the preset target thickness by only 0.5%, and the thickness fluctuation was stably controlled within ±0.2 μm. The first-time feeding qualification rate was 99.3%, proving that the model fully meets the production requirements.

[0247] Example 2

[0248] The calendering roll has a diameter of 300mm, an effective roll surface width of 400mm, a surface roughness Ra=0.01μm, a roll surface parallelism of ±0.3μm, and a roll surface runout of ±0.2μm. The experimental environment was a drying workshop with an ambient dew point ≤-45℃ and an ambient temperature of 23±2℃. The thickness measurement method was completely consistent with S1. The thickness of the finished lithium strip was the thickness of a single layer of metallic lithium, strictly meeting the physical constraint of being ≤ the initial lithium layer thickness of the raw material. The process includes the following steps:

[0249] B1. A 10μm thick lithium metal strip attached to a 40μm thick PP substrate is selected as the raw material. The 180° peel force of the substrate is 1.2N / 25mm. An 8μm thick carbon-coated copper foil is selected as the transfer film with a surface roughness Ra=0.4μm. The thickness is calibrated according to the measurement method in S1, and the theoretical stack thickness is calculated.

[0250] ;

[0251] The maximum thickness of the finished lithium strip is 10μm, and the target thickness is 7μm≤10μm, which meets the physical constraint requirements.

[0252] B2. Set the rolling working gap and the basic rolling force range:

[0253] B21. Calculation of Compensation Baseline Value: According to the calculation formula of S2 of this invention, the baseline value of the working gap compensation for this raw material system under the baseline working condition (total rolling force P=1.0T) is:

[0254] ;

[0255] B22. Determination of Comprehensive Correction Coefficient

[0256] Rolling force correction factor The reference total rolling force P = 1.0T. ;

[0257] Substrate peel force correction factor The substrate 180° peel force is 1.2N / 25mm, which is 0.2N / 25mm higher than the reference value of 1.0N / 25mm. This is calculated according to the rules. ;

[0258] Lithium layer thickness correction factor The lithium layer thickness of the raw material is 10μm, which meets the benchmark requirements. ;

[0259] Overall correction factor: .

[0260] B22, Setting Optimal Values ​​and calibration gradients:

[0261] Calculate the optimal mass production value: The target thickness of 7μm is close to the initial lithium layer thickness of 10μm in the raw material. According to the industrialization value selection guidelines, the 7-10μm range is selected first, and the mass production benchmark is finally determined. =7μm, corresponding to the calendering working gap ;

[0262] Set the model calibration gradient: In Within the feasible process range of 1-10μm, three uniformly distributed ranges of 5μm, 7μm, and 9μm are set with the reference value of 7μm as the center. The gradients correspond to calendering gaps G of 63μm, 65μm, and 67μm, respectively, covering the range of values ​​commonly used in industrial production.

[0263] Set the basic rolling parameters: the optimal range for the total rolling force model calibration is 1.0-2.0T, and the roll surface temperature is controlled at 25±2℃ by circulating water cooling.

[0264] B3. Model calibration experiment and constant fitting:

[0265] B31. Keeping all the above basic parameters fixed, set five speed difference ratios R for each G gradient (0.1, 0.3, 0.5, 0.7, 0.9), and six total rolling forces P for each R gradient (1.0, 1.2, 1.4, 1.6, 1.8, 2.0). Perform three repeated experiments for each GRP parameter combination. Measure the average thickness of the finished lithium strip using the method in S1. After removing outliers using the Grubbs test (α=0.05) and supplementing the experiments, 90 sets of valid experimental data were obtained, as shown in Table 4 below.

[0266] Table 4

[0267]

[0268]

[0269]

[0270]

[0271] B22. Using the multiple linear regression module of Minitab 21 software, Set as the response variable, and G, R, P, R×P, and G×R as continuous independent variables, perform fitting and significance screening (retaining significant parameters with P<0.05), finally obtaining a ternary fully coupled thickness prediction model adapted to this raw material system:

[0272] ;

[0273] Core performance metrics of the model:

[0274] Goodness of fit It meets the accuracy requirement of ≥0.99;

[0275] All parameters had significance values ​​of <0.05, indicating that the statistical validity was met.

[0276] Model applicable boundaries: G=59-68μm (corresponding to δ=1-10μm), R=0.1-0.9, P=1.0-2.0T, finished product thickness ≤10μm initial lithium layer thickness of raw materials.

[0277] B4. Reverse engineering and process verification of an ultrathin lithium strip with a target thickness of 7.0 μm;

[0278] B41. Preconditions and Inverse Solution

[0279] Target thickness: (≤10μm raw material upper limit);

[0280] Production line adaptation parameters: Select total rolling force P=1 T, mass production benchmark rolling working gap G=65μm;

[0281] Model Substitution and Solution: Substitute the above parameters into the calibrated ternary model and rearrange it into a linear equation in one variable R:

[0282] ;

[0283] Equation simplification and calculation:

[0284] a. Combining constant terms: ;

[0285] b. Combining R coefficients: ;

[0286] c. Final solution: Solving for It falls within the applicable range of 0.1-0.9 and requires no adjustment.

[0287] B42. Process Execution and Result Verification

[0288] Process parameter settings: Base line speed of the work roll 5.0 m / min, according to The calculated linear speed of the back support roll is 3.835 m / min; the total rolling force P = 1 T, the rolling working gap G = 65 μm, the roll surface temperature is 25℃, and the other parameters are completely consistent with the aforementioned calibration conditions.

[0289] Production and Testing: After continuous production for 2 hours under a protective atmosphere, samples were taken and multi-point thickness testing was performed according to the measurement method in S1. The sampling data are shown in Table 5 below.

[0290] Table 5

[0291]

[0292] The statistical results in Table 5 show that the actual average thickness of the finished lithium strip is 7.01 μm, which is only 0.14% different from the preset target thickness; the standard deviation of the actual thickness is 0.092 μm, the thickness fluctuation is stably controlled within ±0.2 μm, and the first-time feeding qualification rate is 99.1%, which fully meets the precision requirements of industrial production.

[0293] Comparative Example

[0294] Thickness control was performed using the single-factor linear formula from CN119581491A.

[0295] Except for the thickness control model, all other raw materials, equipment, environment, and operating procedures in this comparative example are completely identical to those in Example 2, strictly adhering to the principle of a single variable. The steps include the following:

[0296] C1, target thickness, raw materials, and S1-S2 parameters are completely consistent with those in Example 2, with a target thickness of 2.0 μm (≤5 μm upper limit of raw materials), G=73 μm, and P=1.5T;

[0297] C2. The final thickness is calculated using the linear formula disclosed in CN119581491A, "final thickness = initial thickness / N", where N is the speed ratio defined in the prior art (N = v_work roll / v_back support roll, which is the reciprocal of R in this invention); the initial lithium layer thickness is 5 μm, the target thickness is 2.0 μm, and the calculated N = 5 / 2 = 2.5, corresponding to the speed difference ratio R = 1 / N = 0.4 in this invention;

[0298] C3. Process Execution and Result Verification: The roller speed was set to R=0.4, and the remaining parameters were the same as in Example 2. During the production process, due to the lack of gap pre-control and rolling force coordination, the lithium layer peeling was uneven, resulting in localized strip breaks and pinhole defects. The thickness data of a few qualified samples are shown in Table 6 below.

[0299] Table 6

[0300]

[0301] According to the statistical results, the actual average thickness of the finished product is ≈ 3.10 μm, the standard deviation is ≈ 0.73 μm, which is 55% different from the target thickness. It is impossible to achieve precise thickness control and the preset production cannot be achieved.

[0302] As can be seen from the comparative examples, Example 1, and Example 2, the existing linear thickness control model only considers the single factor of speed ratio, without involving the influence of rolling gap and total rolling force, and does not reveal the interactive coupling effect of multiple parameters. Therefore, the actual value obtained has a large error compared with the preset value. However, this invention establishes a thickness prediction model with a simple form, clear physical meaning, and high accuracy under all working conditions based on the main effects of rolling gap G, speed difference ratio R, and total rolling force P, as well as the quantitative influence law of linear interaction effect between multiple parameters on the thickness of the finished product. It realizes the accurate preset and reverse solution of the thickness of the finished lithium strip under different gaps, different rolling forces, and different speeds. The model has high prediction accuracy and completely solves the core pain points of existing models, such as logical disconnection of core parameters and failure across working conditions.

[0303] This embodiment also provides a computer device applicable to a method for precise preparation of ultrathin lithium strips with quantitative control, including a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the method for precise preparation of ultrathin lithium strips with quantitative control as proposed in the above embodiment.

[0304] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for precise preparation of ultrathin lithium strips with quantitative control, characterized in that: Includes the following steps: S1. Obtain the calibrated thickness of each layer of the substrate and the theoretical stacking thickness during the substrate calendering process; S2. Based on the theoretical layer thickness, and combining the law of constant volume of metal plastic deformation and the strain constraint mechanism of multilayer film rolling, the working parameters of the calender roll are obtained. S3. Based on the working parameters of the calender roll, construct a ternary fully coupled linear regression model that includes calender working gap G, speed difference ratio R, total rolling force P and multi-parameter interaction terms, and obtain an industrial standard model based on the ternary fully coupled thickness prediction model. S4. Based on the target lithium strip thickness required for production, and combined with the working parameters of the calendering roll, substitute the industrial standard model to perform reverse calculation and obtain the preset speed difference ratio required to achieve the target lithium strip thickness. S5. Based on the total rolling force and the preset speed difference ratio, set the process parameters for preparing ultrathin lithium strips, and quantitatively control the differential rolling transfer and winding according to the GRP multi-parameter collaborative closed-loop adjustment rules. S6. When it is necessary to change the system of the substrate, determine whether it is necessary to adjust the constants of the industrial standard model according to the classification and adaptation rules, and then execute steps S4-S5.

2. The method for precise preparation of ultrathin lithium strips with quantitative control according to claim 1, characterized in that: Step S1 includes: S11. Select a composite lithium strip with a substrate as the raw material and a transfer film compatible with the raw material. S12. Measure the calibration thickness of the lithium metal layer, substrate film, and transfer film; S13. Based on the calibrated thickness of each layer in S12, calculate the theoretical stack thickness during the rolling process. The calculation formula is: （1）； Preferably, the composite lithium strip is made of a substrate film + lithium metal layer bilayer structure, wherein the initial thickness of the lithium metal layer is 5-50 μm, the substrate film is a PP / PE / PET release film with a thickness of 20-100 μm and a peel force of 0.5-2.0 N / 25 mm at 180° at room temperature; the transfer film has a thickness of 5-200 μm and is selected from one of the following: bright copper foil, carbon-coated copper foil, aluminum foil, and PET film. Preferably, the substrate film is a carbon-coated copper foil with a conductive carbon layer coated on one side.

3. The method for precise preparation of ultrathin lithium strips with quantitative control according to claim 1, characterized in that: Step S2 includes: S21. Based on the law of constant volume during plastic deformation of metals and the theory of bending strain in thin film rolling, calculate the benchmark value of the working gap compensation under the benchmark total rolling force. The calculation formula is: （2）； S22. Determine the comprehensive correction factor for the benchmark value. The calculation formula is: ， （3）； in, This is the correction factor for the total rolling force of the calender rolls. This is the substrate film peel force correction factor. The lithium layer calibration thickness correction factor; S23. Obtain the unique and optimal actual value of the working gap compensation amount. : （4）； S24. Determine the target thickness of the lithium strip. Process range: When the target thickness of the lithium band is <1μm The range is 1-3 μm; When the target thickness of the lithium band is 1-5 μm The range is 3-7μm; When the target thickness of the lithium strip is >3μm and close to the initial lithium layer thickness of the raw material... The range is 7-10 μm; S25. Obtain the working parameters of the calendering roll; The working gap of the calender roll is G: ； （5）； The calendering roll diameter is 150-500mm, the roll surface roughness Ra≤0.02μm, the roll surface parallelism≤±0.5μm, and the roll surface runout≤±0.3μm; Total rolling force range of calender rolls: 1.0-5.0T for equipment foundation adaptation, and 1.0-2.0T for model calibration and industrial production. The surface temperature of the calender roll is controlled stably at 20-40℃ through a circulating water / oil cooling system. Preferably, the rules for determining the values ​​of each component coefficient in S22 are as follows: Correction factor for total rolling force of rolling rolls : Using the reference total rolling force P=1.6T as the reference value, For every 0.2T increase in P, the value of K1 increases by 0.08, and so on, until P = 2.0T; for every 0.2T decrease in P, the value of K1 decreases by 0.08, and so on, until P = 1.0T. Substrate film peel force correction factor : The peel force P of the substrate film at 180° at room temperature 剥 =1.0 N / 25 mm is the reference value. ;P 剥 For every 0.5 N / 25 mm increase in elevation, the value of K2 increases by 0.15, and this increase continues until P... 剥 =2.0N / 25mm, P 剥 For every 0.5 N / 25 mm decrease, the value of K2 decreases by 0.15; Lithium layer calibration thickness correction factor : When 5μm≤ When the size is ≤10μm, K3=1; When 10μm < When ≤20μm, K3=1.25; When 20μm < When ≤30μm, K3=1.5; When 30μm < When ≤40μm, K3=1.75; When 40μm < When the size is ≤50μm, K3=2.

4. The method for precise preparation of ultrathin lithium strips with quantitative control according to claim 3, characterized in that: Step S3 includes: S31. Obtain the measured thickness required for the ternary fully coupled linear regression model through multiple repeated calibration experiments. ; S32. For the multiple sets of data points obtained in the experiment (G, R, P, ... A ternary fully coupled thickness prediction model was obtained by performing multiple linear regression fitting; based on the ternary fully coupled thickness prediction model, an industrial standard model was obtained after multiple full factorial experimental data.

5. The method for precise preparation of ultrathin lithium strips with quantitative control according to claim 4, characterized in that: Step S31 includes: Experimental parameters: completely consistent with the basic conditions determined in step S1; Experimental environment: completely consistent with the measurement environment in step S1; The gradient setting rules for the experiment are as follows: The gradient follows the principle of uniform distribution, with the actual value of the working gap compensation amount used. Centered on the center, uniform values ​​are taken in the upper and lower intervals. At least 5 gradient speed difference ratios R are set under each rolling working gap G gradient, and at least 6 gradient total rolling force P are set under each speed difference ratio gradient. Repeatability requirements: Each GRP parameter combination must be performed at least 3 times independently. Data Acquisition: After each set of experiments, the actual thickness of the finished lithium strip is measured according to the thickness measurement method in step S12. The arithmetic mean of three repeated experiments is taken as the measured thickness of that parameter combination. .

6. The method for precise preparation of ultrathin lithium strips with quantitative control according to claim 5, characterized in that: Step S32 includes: S321. Organize the data in S31 into "G, R, P, " Standardize the data into a table and remove outliers; S322, will Let Y be the response variable, and let G, R, P, R×P, and G×R be continuous independent variables (X) to obtain the ternary fully coupled thickness prediction model: （6）； in, The intercept of the model is dimensionless. The main effect coefficient of the calendering gap G is given in μm. -1 ; The main effect coefficient of the velocity difference ratio R is expressed in μm. The main effect coefficient of the total rolling force P is expressed in μm / T; The interaction coefficient between the speed difference ratio R and the total rolling force P is expressed in μm / T. The interaction coefficient between the calendering gap G and the speed difference ratio R, in μm. -1 ; S323. Calculate the average absolute error between the model prediction value and the measured value. When the average absolute error is ≤0.1μm and the maximum relative error is ≤5%, the three-element fully coupled thickness prediction model meets the requirements. Execute step S324. Otherwise, repeat steps S321-S322. S324. Based on the aforementioned ternary fully coupled thickness prediction model, and after multiple full-factor experiments, an industry standard model is obtained. （7）。 7. The method for precise preparation of ultrathin lithium strips with quantitative control according to claim 6, characterized in that: Step S4 includes: S41. Complete the raw material calibration according to steps S1-S2, and determine the optimal value, rolling working gap and total rolling force; S42. Substitute the target lithium strip thickness, rolling working gap, and total rolling force into the calibrated industrial standard model and rearrange it into a linear equation in one variable concerning the speed difference ratio. S43. Solve the linear equation in one variable to obtain the preset speed difference ratio. ; Preferably, the preset speed difference ratio The range is: 0.1-0.

9. If the preset speed difference ratio If the total rolling force is increased or the rolling gap is decreased, the solution is recalculated until the preset speed difference ratio is reached. The requirements are met; If the preset speed difference ratio If the total rolling force is reduced or the rolling gap is increased, the solution is recalculated until the preset speed difference ratio is reached. The requirements are met.

8. The method for precise preparation of ultrathin lithium strips with quantitative control according to claim 7, characterized in that: Step S5 includes: S51. Keep all parameters in steps S1 and S2 unchanged, and set the production process parameters; S52. In a drying workshop environment with an ambient dew point ≤ -45℃, the raw material composite lithium strip and the transfer film are aligned and introduced into the calendering roll. Under the combined action of the shearing force generated by the differential speed and the set total rolling force, the metallic lithium layer is precisely peeled off from the substrate film and simultaneously and uniformly bonded to the surface of the transfer film to complete the ultra-thin forming. S53. During the production process, the thickness of the finished lithium strip is detected. When the deviation between the measured thickness and the target thickness exceeds the set value, it is adjusted according to the GRP multi-parameter collaborative closed-loop adjustment rule. S54. The stripped blank substrate film is wound up and recycled using a constant tension mode, and the transfer film with the ultra-thin lithium tape attached is wound up using a gradient tension mode to obtain the ultra-thin lithium tape finished product. Preferably, the GRP multi-parameter collaborative closed-loop adjustment rule includes: Priority adjustment: Speed ​​difference ratio R > Total rolling force P > Rolling working gap G; Adjust boundary conditions: The total rolling force P is in the range of 1.0-2.0T, and the rolling gap G must not exceed the actual value of the corresponding gap compensation. Within the feasible range, it is forbidden to adjust the rolling gap G across the range, and the thickness of the finished product shall not be greater than the initial lithium layer thickness of the raw material. If the measured thickness is greater than the target thickness: increase the speed difference ratio R, with a single adjustment step size of 0.01-0.05, and after adjustment, run stably for 3-5 roll circumferences before testing again; if the thickness still does not meet the standard, simultaneously fine-tune to increase the total rolling force P, with a single step size of 0.1T, and decrease the rolling working gap G, with a single step size of 0.5μm; If the measured thickness is less than the target thickness: reduce the speed difference ratio R, with a single adjustment step size of 0.01-0.05, and after adjustment, run stably for 3-5 roll circumferences before checking again; if the thickness still does not meet the standard, simultaneously fine-tune to reduce the total rolling force P, with a single step size of 0.1T, and increase the rolling working gap G, with a single step size of 0.5μm; Recalibration threshold for the industrial standard model: If the deviation of the measured thickness still exceeds ±0.5μm after three consecutive adjustments, production should be stopped immediately, and the calibration experiment and coefficient fitting of the ternary fully coupled thickness prediction model should be carried out again.

9. The method for precise preparation of ultrathin lithium strips with quantitative control according to claim 1, characterized in that: Step S6 includes: S61. Complete the parameter calibration and theoretical stacking thickness calculation of the new raw material system according to step S1, and determine the maximum thickness of the new finished lithium strip. S62. Obtain the actual value of the working gap compensation amount and its adaptation range according to step S2. S63. Determine whether the constants of the industrial standard model need to be adjusted according to the hierarchical adaptation rules; S64. Complete the reverse solution of the target thickness according to step S4, and complete continuous production according to step S5. Preferably, the hierarchical adaptation rules include: If the transfer film material and thickness are changed, the substrate film and lithium layer thicknesses remain unchanged, and the new rolling gap G value is still within the range of the actual value δ of the working gap compensation amount of the original calibration model, then the industrial standard model described in S3 can be used directly without re-experimentation. If the substrate film is changed or the lithium layer thickness is altered, the calibration experiment and coefficient fitting of the ternary fully coupled thickness prediction model must be completed again according to S3 to obtain a new industry standard model.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 9.

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