Lithium battery negative electrode coating and drying process control method and system

Abstract

The invention discloses a lithium battery negative electrode coating and drying process control method and system, and relates to the technical field of drying control. The method comprises the steps that a steam adjusting assembly is arranged on the drying equipment; a lithium battery negative electrode coating base material is obtained, the lithium battery negative electrode coating base material is fed into drying equipment to execute a first drying stage, and a steam adjusting assembly is used for controlling a steam solvent at a first steam rate to conduct steam treatment on the lithium battery negative electrode coating base material; and the real-time temperature of the lithium battery negative electrode coating base material is detected, if the temperature rise rate gradient difference of the real-time temperature is smaller than the preset threshold value, a second drying stage is started, and the steam adjusting assembly is used for controlling the steam solvent at the second steam rate to conduct steam treatment on the lithium battery negative electrode coating base material till drying of the lithium battery negative electrode coating base material is completed. The technical problem that in the prior art, the lithium battery negative electrode coating drying effect is poor is solved, and the technical effect that by regulating and controlling the steam rate, the air speed and the temperature in stages, dynamic optimization control over the drying process is achieved, and therefore the drying effect is improved is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of drying control, in particular to a lithium battery negative electrode coating drying process control method and system. BACKGROUND

[0002] In the preparation process of lithium ion batteries, the negative electrode coating process is one of the key links to determine the quality of electrode sheets and the performance of batteries. Usually, the slurry containing binder, conductive agent and solvent is uniformly coated on the surface of the metal current collector, and the solvent is removed through the drying process to obtain a stable electrode coating. However, the existing drying process generally relies on single temperature or air speed adjustment mode, lacks coordinated control of steam environment and hot air environment, resulting in uneven drying rate, local over-drying or residual solvent in the coating during the drying process, thereby affecting the compactness and uniformity of the coating layer, and reducing the cycle stability and safety performance of the electrode sheet. SUMMARY

[0003] The present application provides a lithium battery negative electrode coating drying process control method and system, which solves the technical problem of poor lithium battery negative electrode coating drying effect in the prior art.

[0004] In a first aspect, the present application provides a lithium battery negative electrode coating drying process control method, which comprises: A steam adjusting component is arranged in a drying device; a lithium battery negative electrode coating substrate is obtained, and the lithium battery negative electrode coating substrate is sent into the drying device to perform a first drying stage, the steam adjusting component is used to control the steam treatment of the lithium battery negative electrode coating substrate at a first steam rate, and the air speed adjusting component and the temperature adjusting component of the drying device are set to a first air speed range and a first temperature range; the real-time temperature of the lithium battery negative electrode coating substrate is detected, if the temperature rise rate gradient difference of the real-time temperature is less than a preset threshold value, the second drying stage is entered, the steam adjusting component is used to control the steam treatment of the lithium battery negative electrode coating substrate at a second steam rate, and the air speed adjusting component and the temperature adjusting component of the drying device are set to a second air speed range and a second temperature range, until the drying of the lithium battery negative electrode coating substrate is completed; wherein the first steam rate is greater than the second steam rate, the first air speed range is less than the second air speed range, and the first temperature range is less than the second temperature range.

[0005] In a second aspect, the present application provides a lithium battery negative electrode coating drying process control system, which comprises: The assembly setting module sets a steam adjusting assembly in the drying equipment; the first drying module obtains a lithium battery negative electrode coated substrate, sends the lithium battery negative electrode coated substrate into the drying equipment to perform a first drying stage, controls steam treatment of the lithium battery negative electrode coated substrate by steam solvent at a first steam rate by using the steam adjusting assembly, and simultaneously sets the air speed adjusting assembly and the temperature adjusting assembly of the drying equipment in a first air speed range and a first temperature range; the second drying module detects a real-time temperature of the lithium battery negative electrode coated substrate, enters a second drying stage if a temperature rise rate gradient difference of the real-time temperature is less than a preset threshold, controls steam treatment of the lithium battery negative electrode coated substrate by steam solvent at a second steam rate by using the steam adjusting assembly, and simultaneously sets the air speed adjusting assembly and the temperature adjusting assembly of the drying equipment in a second air speed range and a second temperature range until the lithium battery negative electrode coated substrate is dried completely, wherein the first steam rate is greater than the second steam rate, the first air speed range is less than the second air speed range, and the first temperature range is less than the second temperature range.

[0006] One or more technical solutions provided in the present application have at least the following technical effects or advantages: First, a steam adjusting assembly is set in the drying equipment. Then, a lithium battery negative electrode coated substrate is obtained, the lithium battery negative electrode coated substrate is sent into the drying equipment to perform a first drying stage, steam treatment of the lithium battery negative electrode coated substrate by steam solvent is controlled at a first steam rate by using the steam adjusting assembly, and simultaneously the air speed adjusting assembly and the temperature adjusting assembly of the drying equipment are set in a first air speed range and a first temperature range. Finally, a real-time temperature of the lithium battery negative electrode coated substrate is detected, a second drying stage is entered if a temperature rise rate gradient difference of the real-time temperature is less than a preset threshold, steam treatment of the lithium battery negative electrode coated substrate by steam solvent is controlled at a second steam rate by using the steam adjusting assembly, and simultaneously the air speed adjusting assembly and the temperature adjusting assembly of the drying equipment are set in a second air speed range and a second temperature range until the lithium battery negative electrode coated substrate is dried completely; wherein the first steam rate is greater than the second steam rate, the first air speed range is less than the second air speed range, and the first temperature range is less than the second temperature range. The technical problem of poor drying effect of the lithium battery negative electrode coating in the prior art is solved, dynamic optimization control of the drying process is achieved by controlling the steam rate, air speed and temperature in stages, and the technical effect of improving the drying effect is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0007] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0008] Figure 1 A lithium battery negative electrode coating drying process control method flowchart is provided for the embodiments of the present application. Figure 2 A lithium battery negative electrode coating drying process control system structure diagram is provided for the embodiments of the present application.

[0009] Legend: component setting module 11, first drying module 12, second drying module 13. DETAILED DESCRIPTION

[0010] The present application provides a lithium battery negative electrode coating drying process control method and system, which solves the technical problem of poor lithium battery negative electrode coating drying effect in the prior art.

[0011] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0012] It should be noted that the terms "include" and "have" are intended to cover non-exclusive inclusion, for example, a process, method, system, product or server including a series of steps or units need not be limited to those clearly listed steps or units, but can include other steps or modules not clearly listed or inherent to these processes, methods, products or devices.

[0013] Embodiment one, as shown in the present application provides a lithium battery negative electrode coating drying process control method, wherein the method comprises: Figure 1 A steam adjusting component is arranged in the drying equipment.

[0014] ​In the embodiments of the present application, the steam regulation assembly is integrated into the air inlet end or the internal hot air circulation path of the drying device, and includes a steam generator, a steam delivery pipeline, a steam solvent storage tank, a steam rate regulation valve, and a distributed injection unit. The steam generator is connected to the steam solvent storage tank and used to heat and convert the solvent into steam. The steam delivery pipeline is used to deliver the generated solvent steam into the drying cavity. The steam rate regulation valve is arranged on the steam delivery pipeline and used to adjust the volume fraction and flow rate of the solvent steam entering the drying device in real time according to a control instruction, so as to output different steam rates in the first drying stage and the second drying stage. The distributed injection unit is arranged at multiple positions in the drying cavity to uniformly disperse the steam flow and form a stable steam atmosphere, so as to ensure that the lithium battery negative electrode coated substrate can be fully contacted with an appropriate amount of steam environment in the initial drying stage, reduce the evaporation gradient of the coating surface, and avoid the problems of too fast skinning on the surface of the film layer or internal solvent retention.

[0015] Further, the steam regulation assembly includes a steam generator, a steam delivery pipeline, a steam solvent, and a steam rate regulation valve. The steam rate regulation valve is used to control the volume fraction of the solvent steam entering the drying device to adjust the values of the first steam rate and the second steam rate.

[0016] Further, the steam solvent is N-methyl pyrrolidone or deionized water.

[0017] The steam generator is used to heat and convert the steam solvent into high-temperature steam. The steam solvent can be N-methyl pyrrolidone (NMP) or deionized water. The steam delivery pipeline introduces the generated steam into the working cavity of the drying device and is connected to multiple dispersion outlets to ensure uniform distribution of the steam inside the drying cavity. The steam rate regulation valve is arranged on the steam delivery pipeline and adjusts the steam supply intensity entering the drying device by changing the flow rate and volume fraction of the steam, so as to correspond to the process requirements of the first steam rate and the second steam rate, respectively. The first steam rate is higher than the second steam rate, so as to form a higher steam concentration environment in the initial drying stage, reduce the risk of surface skinning caused by too fast evaporation of the solvent on the surface of the coated substrate, and realize efficient removal of the residual solvent of the coated substrate by reducing the steam rate, increasing the air speed and temperature in the subsequent stage.

[0018] The lithium battery negative electrode coated substrate is obtained, and the lithium battery negative electrode coated substrate is sent into the drying device to perform the first drying stage. The steam regulation assembly is used to control the steam solvent to perform steam treatment on the lithium battery negative electrode coated substrate at the first steam rate, and the air speed regulation assembly and the temperature regulation assembly of the drying device are in the first air speed range and the first temperature range.

[0019] In the embodiments of the present application, the obtaining of the lithium battery negative electrode coated substrate refers to taking the negative electrode current collector (for example, copper foil) on which the slurry has been uniformly coated as the drying object, and continuously or intermittently feeding it into the drying cavity of the drying device through the conveying device. After entering the drying cavity, the first drying stage is performed, in which the steam adjusting assembly outputs solvent vapor at a preset first steam rate, and uniformly acts on the lithium battery negative electrode coated substrate through the spray pipeline arranged in the drying cavity, so that the lithium battery negative electrode coated substrate is subjected to steam treatment in a steam atmosphere, so as to reduce the difference in solvent evaporation rate between the surface layer and the interior of the coating, and avoid the phenomenon of too fast skinning on the surface. At the same time, the air speed adjusting assembly of the drying device controls the circulating air flow in the cavity to be in the first air speed range, so as to ensure that the solvent vapor and the carrier gas on the surface of the coating are uniformly distributed without strong disturbance; and the temperature adjusting assembly keeps the cavity environment in the first temperature range, so that the whole coating is in a mild heating state.

[0020] Further, the method for feeding the lithium battery negative electrode coated substrate into the drying device to perform the first drying stage comprises the following steps: The coating wet film thickness, the coating solvent type, and the steam solvent type of the steam adjusting assembly of the lithium battery negative electrode coated substrate are collected; a heat-mass transfer coupling model is constructed according to the coating solvent type and the steam solvent type, wherein the heat-mass transfer coupling model is obtained by coupling a first heat transfer mapping model and a first mass transfer mapping model; and the coating wet film thickness is analyzed by using the heat-mass transfer coupling model to obtain the first steam rate matched for the lithium battery negative electrode coated substrate.

[0021] Before feeding the lithium battery negative electrode coated substrate into the drying device to perform the first drying stage, the key parameters of the lithium battery negative electrode coated substrate are collected, including the coating wet film thickness, the solvent type used in the coating slurry, and the steam solvent type used in the steam adjusting assembly. A heat-mass transfer coupling model is constructed based on the coating solvent type and the steam solvent type, which is used for predicting and optimizing the drying behavior of the coating wet film under the steam treatment condition, and the heat-mass transfer coupling model is obtained by parameter alignment and range intersection of a first heat transfer mapping model and a first mass transfer mapping model, wherein the first heat transfer mapping model is established by finite element calculation and experimental data mapping relationship, which is used for analyzing the temperature distribution characteristics under different wet film thickness and steam rate conditions, so as to prevent thermal damage of the coating layer surface due to too fast heating; and the first mass transfer mapping model is used for analyzing the diffusion flux and steam concentration variation law of the solvent molecules in the thickness direction of the wet film, so as to ensure that the internal solvent can smoothly migrate to the surface layer and be discharged, and avoid internal residue.

[0022] By inputting the coating wet film thickness parameter into the heat-mass coupling model for calculation and analysis, a first vapor rate matching the current coating conditions can be obtained, which serves as an execution control parameter of the first drying stage vapor regulating component, so that the lithium battery negative electrode coated substrate can form a dynamic balance between the surface layer and internal solvent migration in the early stage of drying, thereby improving the uniformity and stability of the overall drying.

[0023] Further, the method for constructing the first heat transfer mapping model comprises: setting a heat transfer test sample group comprising coating wet film thickness samples and vapor rate samples set under the vapor solvent type and the coating solvent type; establishing a heat transfer model of the lithium battery negative electrode coated substrate by a finite element system, obtaining heat transfer test data of the lithium battery negative electrode coated substrate based on the heat transfer test sample group according to the heat transfer model simulation, the heat transfer test data comprising thermal damage data and temperature distribution data of the lithium battery negative electrode coated substrate; setting a preferred heat transfer-vapor rate range for different coating wet film thicknesses using the heat transfer test data; obtaining a first heat transfer mapping model based on the mapping relationship between different coating wet film thicknesses and corresponding preferred heat transfer-vapor rate ranges.

[0024] First, a heat transfer test sample group is set, which is composed of coating wet film thickness samples and corresponding vapor rate samples under different combinations of vapor solvent type and coating solvent type. Then, a heat transfer model of the lithium battery negative electrode coated substrate is established by a finite element system, which introduces the heat exchange characteristics of the vapor atmosphere and the thermal physical parameters of the wet film material in the boundary conditions, and simulates the influence of vapor rate and film thickness change on heat flow distribution in the time dimension. Based on the heat transfer model, simulation calculation is performed to obtain heat transfer test data of the lithium battery negative electrode coated substrate under the heat transfer test sample group, which includes temperature distribution curves of the coating layer at different positions and thermal damage characteristic data caused by excessive temperature. Then, combined with the simulation output results, the preferred heat transfer-vapor rate range corresponding to different coating wet film thicknesses is extracted, i.e. within this range, surface layer thermal damage can be avoided while ensuring uniform temperature gradient distribution. Finally, by establishing the mapping relationship between different coating wet film thicknesses and their corresponding preferred heat transfer-vapor rate ranges, a first heat transfer mapping model is formed.

[0025] Further, the method for constructing the first heat transfer mapping model comprises: A mass transfer test sample group is set, which includes a coating wet film thickness sample and a vapor velocity sample set under the vapor solvent species and the coating solvent species; a mass transfer model of the lithium battery negative electrode coating substrate is established by a finite element system, mass transfer test data of the lithium battery negative electrode coating substrate based on the mass transfer test sample group is obtained according to the mass transfer model simulation, and the mass transfer test data includes vapor concentration changes and solvent diffusion fluxes of the lithium battery negative electrode coating substrate; the mass transfer test data is used to set a preferred mass transfer-vapor velocity range of different coating wet film thicknesses; and a first mass transfer mapping model is obtained based on a mapping relationship between different coating wet film thicknesses and corresponding preferred mass transfer-vapor velocity ranges.

[0026] Firstly, a mass transfer test sample group is set, which is composed of coating wet film thickness samples and vapor velocity samples under different combinations of vapor solvent species and coating solvent species, for covering experimental and simulation basic data of coating layer solvent volatilization and diffusion characteristics under different working conditions. Subsequently, a mass transfer model of the lithium battery negative electrode coating substrate is established by a finite element system, which adopts a modeling method combining porous medium diffusion theory and boundary layer transfer mechanism, considers solvent molecule diffusion behavior inside the coating wet film and vapor atmosphere concentration gradient together, and introduces solvent partial pressure changes under different vapor velocities in the boundary condition. Simulation calculation is performed based on the mass transfer model to obtain mass transfer test data of the lithium battery negative electrode coating substrate under the conditions of the mass transfer test sample group, which includes vapor concentration change curves inside and on the surface of the coating layer and time-varying solvent diffusion flux distribution. Then, simulation output results are used to extract the corresponding preferred mass transfer-vapor velocity range for different coating wet film thicknesses, that is, uniform migration and smooth volatilization of internal solvents can be achieved in this range, while residual solvents caused by too low vapor velocity or surface layer blocking effect caused by too high vapor velocity are avoided. Finally, a first mass transfer mapping model is obtained by establishing a mapping relationship between different coating wet film thicknesses and their corresponding preferred mass transfer-vapor velocity ranges.

[0027] Further, the heat-mass transfer coupling model is obtained by coupling the first heat transfer mapping model and the first mass transfer mapping model, and the method comprises: The preferred heat transfer-vapor velocity range and the preferred mass transfer-vapor velocity range of the first heat transfer mapping model and the first mass transfer mapping model are aligned to obtain an intersection vapor velocity range of different coating wet film thicknesses; a damage objective function is established, and the damage objective function is called to perform optimization in the intersection vapor velocity range to obtain the first vapor velocity.

[0028] Specifically, the preferred heat transfer-vapor rate range obtained in the first heat transfer mapping model for different coating wet film thicknesses is aligned and compared with the preferred mass transfer-vapor rate range obtained in the first mass transfer mapping model for the same wet film thickness, and by taking the interval intersection of the two, the intersection vapor rate range corresponding to different coating wet film thicknesses is obtained under the condition of considering the inhibition of surface heat damage and the smoothness of internal solvent diffusion; a damage objective function is established within the intersection vapor rate range, the damage objective function minimizes the heat damage risk and the residual solvent concentration of the coating layer as the optimization objective, and a weighting coefficient can be introduced to balance the uniformity of temperature distribution and the efficiency of solvent diffusion. By calling an optimization algorithm to perform optimization calculation on the damage objective function within the intersection vapor rate range, a first vapor rate matching the coating wet film thickness of the lithium battery negative electrode coated substrate is finally obtained, which is input into the vapor regulating component as the vapor supply parameter of the first drying stage, realizing the best drying control under the constraint of heat and mass transfer.

[0029] The damage objective function can be expressed in a weighted form, and the expression is: F(v)=aD(v,h)+bC(v,h)+gG(v,h), wherein v represents the vapor rate, which is constrained within the heat-mass transfer intersection vapor rate range; h represents the coating wet film thickness; D(v,h) represents the heat damage index that the coating layer surface may produce under the vapor rate v and the film thickness h, which is derived from the temperature distribution and thermal stress data of the first heat transfer mapping model; C(v,h) represents the normalized index of residual solvent concentration under the vapor rate v and the film thickness h, which is derived from the solvent diffusion flux and concentration field data of the first mass transfer mapping model; G(v,h) represents the temperature distribution uniformity index, which is used to measure the flatness of the temperature gradient in the coating layer; a, b, g are weighting coefficients, respectively reflecting the importance of heat damage risk, residual solvent and temperature distribution uniformity, and satisfying the sum of 1.

[0030] By calling an optimization algorithm (such as genetic algorithm, particle swarm algorithm or gradient descent method) to optimize the function F(v), the vapor rate when F(v) reaches the minimum value within the intersection vapor rate range is the first vapor rate.

[0031] For the optimal solution of the damage objective function F(v), a genetic algorithm can be used for optimization, which specifically includes: population initialization in the heat-mass transfer intersection steam rate range, randomly generating multiple candidate steam rate individuals, and taking these candidate individuals as the initial population; calculating the fitness of each candidate individual based on the damage objective function, and the fitness value is inversely proportional to the damage objective function value, that is, the smaller the damage objective function value, the higher the fitness value; then, using the selection operator to screen the population individuals according to the fitness distribution, and selecting the better individuals into the mating pool; in the mating pool, perform crossover operation to exchange and combine the individual parameters in the two candidate steam rate intervals to generate new candidate steam rate individuals; at the same time, through mutation operation, randomly perturb individual steam rate individuals to ensure global exploration ability and avoid falling into local optimum. Subsequently, a new generation of population is formed and fitness calculation is performed again, and the selection, crossover and mutation operations are repeatedly performed. Finally, when the number of iterations reaches the preset upper limit, or the population fitness improvement amplitude of several consecutive generations is less than the preset threshold, the algorithm is determined to be converged, and the steam rate corresponding to the individual with the highest fitness in the final population is taken as the first steam rate.

[0032] The real-time temperature of the lithium battery negative electrode coated substrate is detected, and if the temperature rise rate gradient difference of the real-time temperature is less than a preset threshold, the second drying stage is entered, and the steam regulating assembly is used to control the steam treatment of the lithium battery negative electrode coated substrate with a second steam rate, while the air speed adjusting assembly and the temperature adjusting assembly of the drying equipment are in a second air speed range and a second temperature range, until the lithium battery negative electrode coated substrate is dried; wherein the first steam rate is greater than the second steam rate, the first air speed range is less than the second air speed range, and the first temperature range is less than the second temperature range.

[0033] In the embodiments of the present application, the real-time temperature of the lithium battery negative electrode coated substrate in the drying equipment is detected, and the real-time temperature is collected by a temperature sensor array or an infrared temperature measuring device arranged on the surface and internal area of the substrate, and the temperature rise rate and its gradient change are calculated in combination with the time sequence. When the detection result shows that the gradient difference of the temperature rise rate is less than a preset threshold, it indicates that the heat transfer process of the surface layer and the internal area of the coated substrate tends to be balanced, and the drying state enters the solvent residue removal stage from the initial solvent evaporation stage, and the drying process is switched to the second drying stage.

[0034] In the second drying stage, the vapor regulation assembly supplies the vapor solvent at a preset second vapor rate, which is lower than the first vapor rate in the first drying stage, to avoid excessive vapor from inhibiting the discharge of residual solvent. At the same time, the air speed regulation assembly increases the circulating air speed in the drying cavity to the second air speed range to enhance the renewal of the cavity atmosphere and the solvent diffusion driving force; the temperature regulation assembly increases the ambient temperature to the second temperature range to accelerate the evaporation and migration of residual solvent in the coated substrate. Through the synergistic control of the vapor rate reduction and the air speed and temperature increase, the coated substrate can be thoroughly dried while ensuring the integrity of the coating structure.

[0035] Further, the method for controlling the vapor solvent to perform vapor treatment on the lithium battery negative electrode coated substrate at the second vapor rate includes: According to the residual coated wet film thickness of the lithium battery negative electrode coated substrate; the heat and mass transfer coupling model analyzes the residual coated wet film thickness under the constraint of the first vapor rate to obtain the second vapor rate matched for the lithium battery negative electrode coated substrate.

[0036] Specifically, the lithium battery negative electrode coated substrate entering the second drying stage is detected for its state, and the residual coated wet film thickness parameter thereof is extracted, which can be obtained in real time through online optical thickness sensor, laser interference measurement or infrared absorption spectrum analysis, etc.; the residual coated wet film thickness is input into the heat and mass transfer coupling model, and the residual solvent diffusion efficiency and thermal damage risk under different vapor rates are calculated and analyzed under the constraint of the first vapor rate, i.e. the continuity of the temperature distribution and diffusion boundary established by the first stage vapor supply condition is not destroyed; based on the model output result, the optimal vapor rate interval that can simultaneously meet the conditions of no thermal damage to the surface layer and sufficient migration of internal solvent under the current residual wet film thickness is screened out, and optimization is performed in the interval to obtain the optimal second vapor rate.

[0037] Further, the heat and mass transfer coupling model is connected with an adaptive drying regulation model, and the adaptive drying regulation model is trained to obtain vapor rate, air speed parameter and temperature parameter according to the drying target; based on the first drying stage, the adaptive drying regulation model adaptively outputs the first regulation parameter and the first temperature parameter in the first air speed range and the first temperature range according to the first vapor rate; based on the second drying stage, the adaptive drying regulation model adaptively outputs the second regulation parameter and the second temperature parameter in the second air speed range and the second temperature range according to the second vapor rate.

[0038] The heat-mass transfer coupling model is connected with an adaptive drying regulation model. The adaptive drying regulation model is obtained by training with a drying target as an optimization target. The target can include a residual solvent concentration lower than a preset threshold, a uniformity of a coating temperature distribution meeting a requirement, and a surface of a coating layer without thermal damage. During the training process, different steam rates, air speed parameters, and temperature parameters are taken as input variables, and a drying completion degree and structural integrity of a coated substrate are taken as output feedback. A machine learning algorithm such as a neural network, reinforcement learning, or support vector regression is iteratively optimized to form a model capable of adaptively predicting optimal control parameters.

[0039] Based on the first drying stage, the adaptive drying regulation model calls the constraint conditions provided by the heat-mass transfer coupling model, takes the first steam rate as the core input, and performs regulation optimization in the first air speed range and the first temperature range to output matched first regulation parameters and first temperature parameters as real-time control instructions of the drying equipment. After entering the second drying stage, the adaptive drying regulation model performs adaptive calculation according to the second steam rate and the second air speed range and the second temperature range to output second regulation parameters and second temperature parameters, so that the drying equipment can realize adaptive matching and dynamic regulation of parameters in different stages, and ensure the uniformity and stability of the drying of the coated substrate.

[0040] The training process of the adaptive drying regulation model includes the following steps. First, an input feature set is constructed, which includes process variables such as coating wet film thickness, coating solvent type, steam solvent type, steam rate, air speed parameter, and temperature parameter. An output target set is also collected, which includes drying completion degree indicators (such as residual solvent concentration) of the coated substrate, thermal damage indicators (such as surface crack or discoloration detection results), and temperature distribution uniformity indicators (such as temperature gradient mean square deviation). Second, a training objective function is defined, with maximum drying completion degree, minimum thermal damage risk, and optimal temperature distribution uniformity as the optimization direction. A weighted comprehensive objective function can be expressed as L = λ1C + λ2D + λ3G, where C is a residual solvent concentration normalized indicator, D is a thermal damage risk indicator, G is a temperature distribution uniformity indicator, λ1, λ2, and λ3 are adjustable weight coefficients, and the sum is 1.

[0041] In the training process, historical experimental data and data samples generated by the heat and mass transfer coupling model are used as the training set, and machine learning methods are called to model and optimize, such as using deep neural network (DNN) to model the nonlinear relationship between input features and output indicators, or using reinforcement learning (RL) framework to continuously try different combinations of steam speed, wind speed and temperature in the simulation environment, and converge to the optimal strategy through the reward function feedback. During the training iteration process, when the target function value on the validation set decreases by less than a preset threshold for a certain number of rounds, or the overall error converges to the target accuracy, the model training is determined to be completed.

[0042] In summary, the embodiments of the present application have at least the following technical effects: First, a steam adjusting assembly is arranged in the drying equipment. Then, a lithium battery negative electrode coated substrate is obtained, and the lithium battery negative electrode coated substrate is sent into the drying equipment to perform a first drying stage. The steam adjusting assembly is used to control the steam treatment of the lithium battery negative electrode coated substrate by steam solvent at a first steam speed, while the wind speed adjusting assembly and the temperature adjusting assembly of the drying equipment are in a first wind speed range and a first temperature range. Finally, the real-time temperature of the lithium battery negative electrode coated substrate is detected. If the temperature rise rate gradient difference of the real-time temperature is less than a preset threshold, the second drying stage is entered, the steam adjusting assembly is used to control the steam treatment of the lithium battery negative electrode coated substrate by steam solvent at a second steam speed, while the wind speed adjusting assembly and the temperature adjusting assembly of the drying equipment are in a second wind speed range and a second temperature range, until the lithium battery negative electrode coated substrate is dried. Wherein, the first steam speed is greater than the second steam speed, the first wind speed range is less than the second wind speed range, and the first temperature range is less than the second temperature range. The technical problem of poor lithium battery negative electrode coating drying effect in the prior art is solved, and the technical effect of dynamic optimization control of the drying process by stage control of steam speed, wind speed and temperature is achieved, thereby improving the drying effect.

[0043] Embodiment two, based on the same inventive concept as the lithium battery negative electrode coating drying process control method in the foregoing embodiments, as shown in Figure 2 As shown in the drawings, the present application provides a lithium battery negative electrode coating drying process control system, wherein the system comprises: The component setting module 11 sets a steam adjusting component in a drying device; the first drying module 12 obtains a lithium battery negative electrode coated substrate, sends the lithium battery negative electrode coated substrate into the drying device to perform a first drying stage, controls steam treatment of the lithium battery negative electrode coated substrate by steam solvent at a first steam rate by using the steam adjusting component, and simultaneously sets the air speed adjusting component and the temperature adjusting component of the drying device in a first air speed range and a first temperature range; the second drying module 13 detects a real-time temperature of the lithium battery negative electrode coated substrate, enters a second drying stage if a temperature rise rate gradient difference of the real-time temperature is less than a preset threshold, controls steam treatment of the lithium battery negative electrode coated substrate by steam solvent at a second steam rate by using the steam adjusting component, and simultaneously sets the air speed adjusting component and the temperature adjusting component of the drying device in a second air speed range and a second temperature range until the lithium battery negative electrode coated substrate is dried completely, wherein the first steam rate is greater than the second steam rate, the first air speed range is less than the second air speed range, and the first temperature range is less than the second temperature range.

[0044] Further, the component setting module 11 is used to perform the following method: The steam adjusting component includes a steam generator, a steam delivery pipeline, steam solvent, and a steam rate adjusting valve; the steam rate adjusting valve is used to control the volume fraction of solvent steam entering the drying device to adjust the values of the first steam rate and the second steam rate.

[0045] Further, the first drying module 12 is used to perform the following method: The coating wet film thickness of the lithium battery negative electrode coated substrate, the coating solvent type, and the steam solvent type of the steam adjusting component are collected; a heat-mass transfer coupling model is constructed according to the coating solvent type and the steam solvent type, wherein the heat-mass transfer coupling model is obtained by coupling a first heat transfer mapping model and a first mass transfer mapping model; the coating wet film thickness is analyzed by using the heat-mass transfer coupling model to obtain the first steam rate matched for the lithium battery negative electrode coated substrate.

[0046] Further, the first drying module 12 is used to perform the following method: setting a heat transfer test sample group, the heat transfer test sample group including coating wet film thickness samples and vapor rate samples set under the vapor solvent category and the coating solvent category; establishing a heat transfer model of the lithium battery negative electrode coating substrate through a finite element system, obtaining heat transfer test data of the lithium battery negative electrode coating substrate based on the heat transfer test sample group according to the heat transfer model simulation, the heat transfer test data including thermal damage data and temperature distribution data of the lithium battery negative electrode coating substrate; setting preferred heat transfer-vapor rate ranges of different coating wet film thicknesses by using the heat transfer test data; obtaining a first heat transfer mapping model based on a mapping relationship between different coating wet film thicknesses and corresponding preferred heat transfer-vapor rate ranges.

[0047] Further, the first drying module 12 is used to perform the following method: setting a mass transfer test sample group, the mass transfer test sample group including coating wet film thickness samples and vapor rate samples set under the vapor solvent category and the coating solvent category; establishing a mass transfer model of the lithium battery negative electrode coating substrate through a finite element system, obtaining mass transfer test data of the lithium battery negative electrode coating substrate based on the mass transfer test sample group according to the mass transfer model simulation, the mass transfer test data including vapor concentration changes and solvent diffusion fluxes of the lithium battery negative electrode coating substrate; setting preferred mass transfer-vapor rate ranges of different coating wet film thicknesses by using the mass transfer test data; obtaining a first mass transfer mapping model based on a mapping relationship between different coating wet film thicknesses and corresponding preferred mass transfer-vapor rate ranges.

[0048] Further, the first drying module 12 is used to perform the following method: aligning preferred heat transfer-vapor rate ranges and preferred mass transfer-vapor rate ranges of the first heat transfer mapping model and the first mass transfer mapping model to obtain intersection vapor rate ranges of different coating wet film thicknesses; establishing a damage objective function, and calling the damage objective function to perform optimization in the intersection vapor rate ranges to obtain the first vapor rate.

[0049] Further, the second drying module 13 is used to perform the following method: According to the remaining coating wet film thickness of the lithium battery negative electrode coating substrate; the heat transfer-mass transfer coupling model analyzes the remaining coating wet film thickness with the first vapor rate as a constraint condition to obtain a second vapor rate matched for the lithium battery negative electrode coating substrate.

[0050] Further, the second drying module 13 is used to perform the following method: The heat-mass transfer coupling model is connected with an adaptive drying adjustment model, the adaptive drying adjustment model is trained to obtain a vapor rate, a wind speed parameter and a temperature parameter for achieving a drying target; based on the first drying stage, the adaptive drying adjustment model adaptively outputs a first adjustment parameter and a first temperature parameter in the first wind speed range and the first temperature range according to the first vapor rate; based on the second drying stage, the adaptive drying adjustment model adaptively outputs a second adjustment parameter and a second temperature parameter in the second wind speed range and the second temperature range according to the second vapor rate.

[0051] Further, the first drying module 12 is used to execute the following method: The vapor solvent is N-methyl pyrrolidone or deionized water.

[0052] It should be noted that the above-mentioned sequence of the embodiments of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments. The above describes a specific embodiment of the present application. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multi-task processing and parallel processing are possible or can be advantageous.

[0053] The above only describes the preferred embodiments of the present application and does not limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0054] The present application is only an exemplary description of the present application, and any and all modifications, changes, combinations or equivalents within the scope of the present application are considered to be covered by the present application. Obviously, those skilled in the art can make various modifications and changes to the present application without departing from the scope of the present application. Thus, if these modifications and changes of the present application belong to the scope of the present application and its equivalents, the present application intends to include these modifications and changes.

Claims

1. A method of controlling a coating and drying process for a lithium anode, characterized by, The method comprises: a steam regulation assembly is arranged in a drying device; a lithium battery negative electrode coated substrate is obtained, and the lithium battery negative electrode coated substrate is sent into the drying device to perform a first drying stage, the steam regulation assembly is used to control steam solvent to perform steam treatment on the lithium battery negative electrode coated substrate at a first steam rate, and a wind speed regulation assembly and a temperature regulation assembly of the drying device are in a first wind speed range and a first temperature range; a real-time temperature of the lithium battery negative electrode coated substrate is detected, if a temperature rising rate gradient difference of the real-time temperature is less than a preset threshold value, a second drying stage is entered, the steam regulation assembly is used to control steam solvent to perform steam treatment on the lithium battery negative electrode coated substrate at a second steam rate, and the wind speed regulation assembly and the temperature regulation assembly of the drying device are in a second wind speed range and a second temperature range, until the lithium battery negative electrode coated substrate is dried completely; wherein the first steam rate is greater than the second steam rate, the first wind speed range is less than the second wind speed range, and the first temperature range is less than the second temperature range.

2. The method of claim 1, wherein, The steam regulation assembly comprises a steam generator, a steam delivery pipeline, steam solvent, and a steam rate regulation valve; The steam rate regulation valve is used to control the volume fraction of solvent steam entering the drying device to adjust the values of the first steam rate and the second steam rate.

3. The method of claim 1, wherein, The method for sending the lithium battery negative electrode coated substrate into the drying device to perform the first drying stage comprises: The coating wet film thickness, the coating solvent type, and the steam solvent type of the steam regulation assembly of the lithium battery negative electrode coated substrate are collected; A heat-mass transfer coupling model is constructed according to the coating solvent type and the steam solvent type, wherein the heat-mass transfer coupling model is obtained by coupling a first heat transfer mapping model and a first mass transfer mapping model; The coating wet film thickness is analyzed by using the heat-mass transfer coupling model, and a first steam rate matched for the lithium battery negative electrode coated substrate is obtained.

4. The method of claim 3, wherein, The method for constructing the first heat transfer mapping model comprises: A heat transfer test sample group is set, the heat transfer test sample group comprises coating wet film thickness samples and steam rate samples set under the steam solvent type and the coating solvent type; A heat transfer model of the lithium battery negative electrode coated substrate is established by using a finite element system, heat transfer test data of the lithium battery negative electrode coated substrate based on the heat transfer test sample group is obtained by simulation according to the heat transfer model, and the heat transfer test data comprises heat damage data and temperature distribution data of the lithium battery negative electrode coated substrate; The heat transfer test data is used to set a preferred heat transfer-steam rate range of different coating wet film thicknesses; A first heat transfer mapping model is obtained based on a mapping relationship between different coating wet film thicknesses and corresponding preferred heat transfer-steam rate ranges.

5. The method of claim 3, wherein, The method for constructing the first mass transfer mapping model comprises: A mass transfer test sample group is set, the mass transfer test sample group comprises coating wet film thickness samples and steam rate samples set under the steam solvent type and the coating solvent type; A mass transfer model of the lithium battery negative electrode coated substrate is established by a finite element system, mass transfer test data of the lithium battery negative electrode coated substrate based on the mass transfer test sample group is obtained according to the mass transfer model simulation, and the mass transfer test data includes vapor concentration change and solvent diffusion flux of the lithium battery negative electrode coated substrate; A preferred mass transfer-vapor rate range of different coating wet film thicknesses is set by using the mass transfer test data; A first mass transfer mapping model is obtained based on the mapping relationship between different coating wet film thicknesses and corresponding preferred mass transfer-vapor rate ranges.

6. The method of claim 3, wherein, The heat-mass coupling model is obtained by coupling the first heat mapping model and the first mass transfer mapping model, and the method comprises: The preferred heat-vapor rate range and the preferred mass transfer-vapor rate range of the first heat mapping model and the first mass transfer mapping model are aligned to obtain the intersection vapor rate range of different coating wet film thicknesses; An injury objective function is established, and the injury objective function is called to perform optimization in the intersection vapor rate range to obtain the first vapor rate.

7. The method of claim 3, wherein, The vapor regulating component is used to control the vapor treatment of the lithium battery negative electrode coated substrate by the vapor solvent at the second vapor rate, and the method for obtaining the second vapor rate comprises: According to the remaining coating wet film thickness of the lithium battery negative electrode coated substrate; The heat-mass coupling model analyzes the remaining coating wet film thickness under the constraint condition of the first vapor rate to obtain the second vapor rate matched for the lithium battery negative electrode coated substrate.

8. The method of claim 3, wherein, The heat-mass coupling model is connected with an adaptive drying adjustment model, and the adaptive drying adjustment model is trained to obtain vapor rate, air speed parameter and temperature parameter according to drying target; Based on the first drying stage, the adaptive drying adjustment model adaptively outputs the first adjustment parameter and the first temperature parameter in the first air speed range and the first temperature range according to the first vapor rate; Based on the second drying stage, the adaptive drying adjustment model adaptively outputs the second adjustment parameter and the second temperature parameter in the second air speed range and the second temperature range according to the second vapor rate.

9. The method of claim 1, wherein, The vapor solvent is N-methyl pyrrolidone or deionized water.

10. A lithium anode coating drying process control system characterized by, A system for implementing the lithium battery negative electrode coating drying process control method of any one of claims 1-9, the system comprising: A component setting module: setting a vapor regulating component in a drying device; A first drying module: obtaining a lithium battery negative electrode coated substrate, feeding the lithium battery negative electrode coated substrate into the drying device to perform a first drying stage, and using the vapor regulating component to control the vapor treatment of the lithium battery negative electrode coated substrate by the vapor solvent at a first vapor rate, while making the air speed adjusting component and the temperature adjusting component of the drying device in a first air speed range and a first temperature range; The second drying module detects the real-time temperature of the lithium battery negative electrode coated substrate. If the temperature rising rate gradient difference of the real-time temperature is less than a preset threshold, the second drying stage is entered. The steam adjusting assembly is used to control the steam treatment of the lithium battery negative electrode coated substrate by a second steam rate. Meanwhile, the air speed adjusting assembly and the temperature adjusting assembly of the drying device are in a second air speed range and a second temperature range until the lithium battery negative electrode coated substrate is dried completely. The first steam rate is greater than the second steam rate. The first air speed range is less than the second air speed range. The first temperature range is less than the second temperature range.

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