A simulation method and system for grain growth process of high-nickel positive electrode material

Abstract

The application discloses a simulation method and system for grain growth process of high-nickel positive electrode material, wherein according to the grain growth data obtained from sintering experiment of the high-nickel positive electrode material, the primary grain distribution law under different temperatures and different times is obtained; according to the primary grain distribution law, the grain growth mechanism formula most conforming to the experimental material is established through mechanism equation MSE matching; the grain growth activation energy of the high-nickel positive electrode material is identified through the relationship between the average particle size and the temperature and the time; according to the grain growth mechanism formula and the grain growth activation energy, the grain growth parameters of the high-nickel positive electrode material are obtained, and the grain growth rate of the high-nickel positive electrode material under different temperatures is obtained; according to the characteristics of the grain growth process of the high-nickel positive electrode material required to be simulated, the probabilistic hedging cellular automaton is established, the grain growth rate rule is proposed, and the grain growth is realized in the cellular automaton. The application provides a basis for improving the sintering system, improving the product yield and improving the electrochemical performance of the product.

Description

Technical Field

[0001] This invention relates to the field of high-nickel cathode material preparation technology, and in particular discloses a simulation method and system for the grain growth process of high-nickel cathode materials. Background Technology

[0002] To address the challenges of fossil fuel consumption and severe environmental pollution, lithium-ion batteries (LIBs) are gaining increasing attention in practical applications such as portable electronic devices and electric vehicles due to their inherent electrochemical properties, including good cycle performance, high energy and power density, good energy storage capacity, and environmental friendliness. High-nickel cathode materials possess advantages such as high specific capacity, strong rate capability, good structural stability, and low cost, making them one of the most promising key materials for lithium-ion batteries at present and an important material source for the commercial production of lithium-ion batteries.

[0003] Currently, for large-scale industrial applications, NCM (LiNi) x Co y Mn 1-x-y High-nickel cathode materials (lithium nickel cobalt manganese oxide, O2) are typically prepared using solid-state sintering, a simple and low-cost process. In actual production, the material grains need to grow to a certain size to meet technical specifications, a very slow process that usually takes over ten hours. The size of the primary grain is of paramount importance. The performance of high-nickel cathode materials is closely related to key performance indicators such as cycle life and capacity.

[0004] However, due to limitations in the production environment, the growth state of primary grains inside the furnace has always been an important yet difficult-to-measure microscopic parameter. Therefore, obtaining information on the growth state of primary grains during sintering and understanding the complex microstructural evolution during sintering is of great significance for overcoming the bottlenecks in the industrial production of high-nickel cathode materials.

[0005] The sintering process of high-nickel cathode materials in NCM is a complex chemical reaction process, mainly involving the chemical formation of materials and grain growth. Grain growth refers to the continuous increase in grain size under heating, which is influenced by many factors. Detailed information about grain growth during sintering is limited. Most studies only focus on the final sintered product and do not compare it with intermediate state data from the actual process. Furthermore, a complete study of the unique physical properties and growth patterns during the sintering of high-nickel cathode materials is lacking.

[0006] Therefore, the aforementioned defects in existing research on grain growth during the sintering process of high-nickel cathode materials are technical problems that urgently need to be solved. Summary of the Invention

[0007] This invention provides a method and system for simulating the grain growth process of high-nickel cathode materials, aiming to address the aforementioned deficiencies in existing research on grain growth during the sintering process of high-nickel cathode materials.

[0008] One aspect of the present invention relates to a method for simulating the grain growth process of a high-nickel cathode material, comprising the following steps:

[0009] Based on the grain growth data obtained from the sintering experiment of high-nickel cathode material, the primary grain distribution law under different temperatures and times was obtained.

[0010] Based on the primary grain distribution law, the grain growth mechanism formula that best matches the experimental material was established by matching the mechanistic equation MSE; the activation energy of grain growth of high-nickel cathode material was identified by the relationship between average grain size and temperature and time.

[0011] Based on the grain growth mechanism formula and grain growth activation energy, the grain growth parameters of high-nickel cathode material were obtained, and the grain growth rate of high-nickel cathode material at different temperatures was obtained.

[0012] Based on the characteristics of the grain growth process of the high-nickel cathode material to be simulated, a probabilistic hedging cellular automaton is established, a grain growth rate rule is proposed, grain growth is realized in the cellular automaton, a mass migration rule is proposed, and a smooth surface generated by grain boundary surface tension is realized.

[0013] The obtained grain growth activation energy and grain growth rate are input into the probabilistic hedging cellular automaton model; the evolution of the nodal particle state is carried out according to the grain growth rate rule and the mass migration rule, and the probabilistic hedging cellular automaton simulation results of the oxidation reaction of high nickel cathode material are obtained; finally, the dynamic evolution of grain growth in the sintering process of high nickel cathode material is realized.

[0014] Furthermore, based on the primary grain distribution law, a grain growth mechanism formula that best matches the experimental material was established through mechanistic equation (MSE) matching; the steps to identify the grain growth activation energy of the high-nickel cathode material by analyzing the relationship between average grain size and temperature and time include:

[0015] The scaling factor that best matches each theoretical formula is obtained by scaling the actual primary grain size distribution.

[0016] Calculate the mean square error between each theoretical formula and the scaled actual data;

[0017] The formula with the smallest mean square error is selected as the theoretical formula that best matches the actual data.

[0018] Based on theoretical formulas, the limiting grain size R is obtained by reverse calculation. cr .

[0019] Furthermore, based on the primary grain distribution law, a grain growth mechanism formula that best matches the experimental material was established through mechanistic equation (MSE) matching; the steps to identify the grain growth activation energy of the high-nickel cathode material by analyzing the relationship between average grain size and temperature and time include:

[0020] The average grain size D was calculated by statistically analyzing the grain size in SEM images of isothermal sintered samples at different temperatures.

[0021] A univariate linear regression model of lnD and lnt at multiple temperatures was established to obtain the grain growth index n;

[0022] By changing the sintering temperature, the least squares fit of lnD and 1 / T is performed according to the following formula. Based on the linear relationship between lnD and 1 / T, the grain growth activation energy Q can be obtained.

[0023]

[0024] Where n is the grain growth index, D is the average grain size, k0 is the initial crystal growth rate, t is time, Q is the activation energy for grain boundary migration, R is the gas constant, and T is the absolute temperature.

[0025] Furthermore, based on the grain growth mechanism formula and grain growth activation energy, the grain growth parameters of the high-nickel cathode material are obtained, and the steps to obtain the grain growth rate of the high-nickel cathode material at different temperatures include:

[0026] Based on the primary grain size distribution data obtained from the experiment under the same isothermal time, the limiting grain size R at different times was obtained. cr Value; based on the limiting grain size R at different times. cr The value is obtained through linear regression. A function of time t; for Differentiating the function with respect to time t yields the variation function of αMσ under the same initial grain distribution, constant isothermal temperature, and different isothermal times.

[0027] Simultaneously, the effect of isothermal temperature T on grain growth was studied. The results show that temperature mainly affects grain boundary mobility M, which is described by a temperature-induced thermal activation relationship:

[0028]

[0029] Where M is the grain boundary mobility, M o K is the grain boundary migration coefficient; Q is the activation energy for grain boundary migration, k B Boltzmann's constant is given by T, where T is the absolute temperature.

[0030] After determining the activation energies at different temperatures, the grain growth rates at different temperatures are obtained using the following formula:

[0031]

[0032]

[0033] in, Let M0σα be the grain growth rate, M0σα be the set of grain growth kinetic parameters, M be the grain boundary mobility, M0 be the grain boundary migration coefficient, and Q be the activation energy for grain boundary migration, k0σα ... B R is Boltzmann's constant, T is absolute temperature; cr R is the limiting grain size, and R is the equivalent radius of the grain.

[0034] Furthermore, based on the primary grain size distribution data obtained from the experiment under the same isothermal time, the grain limiting size R at different times was obtained. cr Value; obtained through linear regression based on the grain limit size Rcr value at different times. A function of time t; for In the step of differentiating the function of αMσ with respect to time t to obtain the variation function of αMσ under the same initial grain distribution, constant isothermal temperature, and different isothermal times, in order to identify the grain limiting size R cr The limiting grain size is extracted using primary grain distribution data from the sintering process of high-nickel cathode materials. For a given grain distribution, the limiting grain size is obtained using the following formula:

[0035]

[0036] Among them, R cr Where is the limiting grain size, and P(u) is the theoretical grain size distribution; This is the scaled curve.

[0037] Another aspect of the present invention relates to a simulation system for the grain growth process of a high-nickel cathode material, comprising:

[0038] The first acquisition module is used to obtain the primary grain distribution pattern at different temperatures and times based on the grain growth data obtained from the sintering experiment of high-nickel cathode material.

[0039] The first module is used to establish the grain growth mechanism formula that best matches the experimental material based on the primary grain distribution law and by matching the mechanism equation MSE; and to identify the grain growth activation energy of the high-nickel cathode material by the relationship between average grain size and temperature and time.

[0040] The second acquisition module is used to obtain the grain growth parameters of high-nickel cathode material according to the grain growth mechanism formula and the grain growth activation energy, and to obtain the grain growth rate of high-nickel cathode material at different temperatures.

[0041] The second module is used to establish a probabilistic hedging cellular automaton based on the characteristics of the grain growth process of the high-nickel cathode material to be simulated, propose grain growth rate rules, realize grain growth in the cellular automaton, propose mass migration rules, and realize the smooth surface generated by grain boundary surface tension.

[0042] The third acquisition module is used to input the obtained grain growth activation energy and grain growth rate into the probabilistic hedging cellular automaton model; based on the grain growth rate rule and the mass migration rule, the evolution of the node particle state is carried out to obtain the probabilistic hedging cellular automaton simulation results of the oxidation reaction of high-nickel cathode material; finally, the dynamic evolution of grain growth in the sintering process of high-nickel cathode material is realized.

[0043] Furthermore, the first establishment module includes:

[0044] The first acquisition unit is used to obtain the scaling factor that best matches each theoretical formula by scaling the actual primary grain size distribution.

[0045] The first calculation unit is used to calculate the mean square error between each theoretical formula and the scaled actual data, respectively.

[0046] Selecting a unit is used to choose the formula with the smallest mean square error as the theoretical formula that best matches the actual data.

[0047] The reverse calculation unit is used to reverse calculate the limiting grain size R based on the theoretical formula. cr .

[0048] Furthermore, the first establishment module includes:

[0049] The second calculation unit is used to calculate the average grain size D by statistically analyzing the grain size in the SEM images of isothermal sintered samples at different temperatures.

[0050] The third calculation unit is used to establish a univariate linear regression model of 1nD and lnt at multiple temperatures to obtain the grain growth index n.

[0051] The fourth calculation unit is used to change the sintering temperature. According to the following formula, the least squares fit is performed on lnD and 1 / T. Based on the linear relationship between lnD and 1 / T, the grain growth activation energy Q can be obtained.

[0052]

[0053] Where n is the grain growth index, D is the average grain size, k0 is the initial crystal growth rate, t is time, Q is the activation energy for grain boundary migration, R is the gas constant, and T is the absolute temperature.

[0054] Furthermore, the second acquisition module includes:

[0055] The second acquisition unit is used to acquire the limiting grain size R at different times based on the primary grain size distribution data obtained in the experiment under the same isothermal time. cr Value; obtained through linear regression based on the limiting grain size Rcr value at different times. A function of time t; for Differentiating the function with respect to time t yields the variation function of αMσ under the same initial grain distribution, constant isothermal temperature, and different isothermal times.

[0056] The fifth acquisition unit is used to simultaneously study the effect of isothermal temperature T on grain growth. Research shows that temperature mainly affects grain boundary mobility M, which is described by the thermal activation relationship of temperature:

[0057]

[0058] Where M is the grain boundary mobility, M0 is the grain boundary migration coefficient; Q is the activation energy for grain boundary migration, k B It is Boltzmann's constant, and T is the absolute temperature;

[0059] The sixth calculation unit is used to obtain the grain growth rate at different temperatures according to the following formula after determining the activation energy at different temperatures:

[0060]

[0061]

[0062] in, Let M0σα be the grain growth rate, M be the grain growth kinetic parameter set, M be the grain boundary mobility, M0 be the grain boundary migration coefficient, and Q be the activation energy for grain boundary migration, k0σα ... B R is Boltzmann's constant, T is absolute temperature; cr R is the limiting grain size, and R is the equivalent grain radius.

[0063] Furthermore, in the second acquisition unit, in order to identify the limiting grain size, the limiting grain size is extracted using primary grain distribution data from the sintering process of the high-nickel cathode material; for a given grain distribution, the limiting grain size is obtained using the following formula:

[0064]

[0065] Among them, R cr Where is the limiting grain size, and P(u) is the theoretical grain size distribution; This is the scaled curve.

[0066] The beneficial effects achieved by this invention are as follows:

[0067] This invention provides a method and system for simulating the grain growth process of high-nickel cathode materials. Based on grain growth data obtained from sintering experiments of high-nickel cathode materials, the method obtains the primary grain distribution pattern at different temperatures and times. Based on the primary grain distribution pattern, a grain growth mechanism formula that best matches the experimental material is established through MSE (Mechanism-Specific Equation) matching. The activation energy for grain growth of high-nickel cathode materials is identified by the relationship between average grain size and temperature and time. Based on the grain growth mechanism formula and the activation energy, the grain growth parameters of high-nickel cathode materials are obtained, and the grain growth rate of high-nickel cathode materials at different temperatures is obtained. Based on the characteristics of the grain growth process of the high-nickel cathode material to be simulated, a probabilistic hedging cellular automaton is established, a grain growth rate rule is proposed, grain growth is realized in the cellular automaton, and a mass migration rule is proposed to realize the smooth surface generated by the grain boundary surface tension. The obtained grain growth activation energy and grain growth rate are input into the probabilistic hedging cellular automaton model. The evolution of the nodal particle state is carried out according to the grain growth rate rule and the mass migration rule to obtain the probabilistic hedging cellular automaton simulation results of the oxidation reaction of the high-nickel cathode material. Finally, the dynamic evolution of grain growth in the sintering process of the high-nickel cathode material is realized. The present invention provides a novel method and system for simulating the grain growth process of high-nickel cathode materials. This method and system not only analyzes the relevant thermodynamics of the grain growth process but also effectively simulates the dynamic changes in the grain growth progress, thus providing guidance for optimizing the sintering process. Based on a probabilistic hedging cellular automata model, the method dynamically describes the morphological changes during the grain growth process, providing a reference for macroscopic phenomena from the microscopic process. This provides a basis for improving the sintering process, increasing product yield, and improving the electrochemical performance of the product. Attached Figure Description

[0068] Figure 1 A schematic flowchart of an embodiment of the simulation method for the grain growth process of high-nickel cathode material provided by the present invention;

[0069] Figure 2 SEM images of the NCM811 high-nickel cathode material synthesized at different heating rates in the heating section of this invention, and a schematic diagram of the primary grain size distribution.

[0070] Figure 3 SEM images of the NCM811 high-nickel cathode material synthesized at different sintering (isothermal) times in the isothermal section of this invention, and a schematic diagram of the primary grain size distribution.

[0071] Figure 4 SEM images of NCM811 ternary cathode materials synthesized at different sintering (isothermal) temperatures during the isothermal section of this invention, and a schematic diagram of the primary grain size distribution.

[0072] Figure 5 This is a univariate linear regression diagram of 1nD and lnt at different temperatures according to the present invention;

[0073] Figure 6 Least square fitting plots of 1nD and 1 / T at different times in this invention;

[0074] Figure 7 This is a schematic diagram of the initial state of the cell space obtained by SEM image of high-nickel cathode material in this invention;

[0075] Figure 8 This is a schematic diagram of the simulation results of synthesizing NCM811 high-nickel cathode material under different sintering times in the isothermal section (800℃) of the present invention.

[0076] Figure 9 This is a schematic diagram of the simulation results of synthesizing NCM811 high-nickel cathode material under different sintering times in the isothermal section (800℃) of the present invention.

[0077] Figure 10 The figures show the grain size distribution curves and surface plots of primary grains simulated by cellular automata at different temperatures according to the present invention.

[0078] Figure 11 A functional block diagram of an embodiment of the simulation system for the grain growth process of high-nickel cathode material provided by the present invention;

[0079] Figure 12 for Figure 11 A functional module diagram of the first establishment module in the first embodiment shown in the figure;

[0080] Figure 13 for Figure 11 A functional module diagram of the second embodiment of the first establishment module shown in the figure;

[0081] Figure 14 for Figure 11 The diagram shows a functional module schematic of one embodiment of the second acquisition module.

[0082] Explanation of icon numbers:

[0083] 10. First Acquisition Module; 20. First Establishment Module; 30. Second Acquisition Module; 40. Second Establishment Module; 50. Third Acquisition Module; 21. First Acquisition Unit; 22. First Calculation Unit; 23. Selection Unit; 24. Backward Calculation Unit; 25. Second Calculation Unit; 26. Third Calculation Unit; 27. Fourth Calculation Unit; 31. Second Acquisition Unit; 32. Fifth Calculation Unit; 33. Sixth Calculation Unit. Detailed Implementation

[0084] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0085] like Figure 1 and Figure 2 As shown, the first embodiment of the present invention proposes a method for simulating the grain growth process of high-nickel cathode materials, including the following steps:

[0086] Step S100: Based on the grain growth data obtained from the sintering experiment of high-nickel cathode material, obtain the primary grain distribution law at different temperatures and times.

[0087] Based on grain growth data obtained from sintering experiments of high-nickel cathode materials, the primary grain distribution patterns at different temperatures and times were determined. The main factors influencing the grain growth rate of high-nickel cathode materials during the sintering process were analyzed to clarify the specific evolution of grain growth.

[0088] The mechanism of primary grain growth during the sintering of high-nickel cathode materials is analyzed using scanning electron microscopy (SEM) data.

[0089] Sintered materials consist of precursors (Ni 0.8 Co 0.1 Mn 0.1 (OH)2) and LiOH·H2O are mixed in a certain proportion, and the two raw materials, which are in the form of granular powder, are uniformly mixed and stirred. Then, the mixture is placed in a sagger and conveyed into a roller kiln for sintering. During the sintering process in the roller kiln, the high-nickel cathode material undergoes a complex grain growth process.

[0090] The overall sintering process mainly consists of three parameters: the heating rate in the heating section, the isothermal temperature in the isothermal section, and the isothermal time. To investigate the influence of these sintering parameters on the grain growth rate, this embodiment designed sintering experiments with different heating rates, isothermal temperatures, and isothermal times, while keeping other variables constant.

[0091] from Figure 2 (a) Figure 2 (b) Figure 2(c) It can be clearly seen that the primary grains are rice-grain shaped, and the grain size and morphology do not change significantly with the increase of the heating rate. Figure 2 In (d), the primary grain size distribution curves are very similar, and their mean square error is statistically less than 5%. The change in the heating rate during the heating stage has a relatively small impact on the grain size. Figure 2 (a) is a schematic diagram of the primary grain size distribution of the NCM811 high-nickel cathode material synthesized at a heating rate of 1.5 K / min in the heating section of the present invention. Figure 2 (b) is a schematic diagram of the primary grain size distribution of the NCM811 high-nickel cathode material synthesized at a heating rate of 2K / min during the heating stage of the present invention. Figure 2 (c) is a schematic diagram of the primary grain size distribution of the NCM811 high-nickel cathode material synthesized at a heating rate of 3K / min during the heating stage of the present invention. Figure 2 (d) is a SEM image of the NCM811 high-nickel cathode material synthesized at different heating rates in the heating section of this invention.

[0092] from Figure 3 (a) Figure 3 (b) Figure 3 (c) It can be seen that as the isothermal time increases, the primary grain size tends to increase and the morphology becomes more and more rounded, but the change is small. Figure 3 Figure d shows that the primary grain size distribution curve exhibits a rightward shift and broadening with increasing isothermal time. The isothermal time in the isothermal phase has a significant impact on grain size. Specifically, Figure 3 (a) is a schematic diagram of the primary grain size distribution of the NCM811 high-nickel cathode material synthesized in the isothermal section during a 3-hour sintering (isothermal) time according to the present invention. Figure 3 (b) is a schematic diagram of the primary grain size distribution of the NCM811 high-nickel cathode material synthesized under a constant temperature sintering (constant temperature) time of 6 h in the constant temperature section of the present invention; Figure 3 (c) is a schematic diagram of the primary grain size distribution of the NCM811 high-nickel cathode material synthesized under a constant temperature sintering (constant temperature) time of 9 h in the constant temperature section of this invention. Figure 3 (d) is a SEM image of the NCM811 high-nickel cathode material synthesized in the isothermal section of the present invention at different sintering (isothermal) times.

[0093] from Figure 4 (a) Figure 4 (b) Figure 4 As shown in (c), the primary grain size and morphology of the ternary cathode material change significantly with increasing temperature, especially at 850℃. Meanwhile, from... Figure 4(d) As can be seen, the overall primary grain size distribution curves showed a strong rightward shift and broadening. This indicates that temperature in the isothermal range strongly affects the primary grain growth of the high-nickel cathode material. Figure 4 (a) is a schematic diagram of the primary grain size distribution of the NCM811 high-nickel cathode material synthesized at a sintering (isothermal) temperature of 750℃ in the isothermal section of the present invention. Figure 4 (b) is a schematic diagram of the primary grain size distribution of the NCM811 high-nickel cathode material synthesized at a sintering (isothermal) temperature of 800℃ in the isothermal section of the present invention. Figure 4 (c) is a schematic diagram of the primary grain size distribution of the NCM811 high-nickel cathode material synthesized at a sintering (isothermal) temperature of 850℃ in the isothermal section of the present invention. Figure 4 (d) is a SEM image of the NCM811 high-nickel cathode material synthesized at different sintering (isothermal) temperatures in the isothermal section of this invention.

[0094] In summary, during the production of high-nickel cathode materials, the heating rate in the heating stage has a relatively small impact on grain growth, while the isothermal time in the isothermal stage has a significant impact, and the isothermal temperature in the isothermal stage has the most significant impact. It is evident that primary grain growth of high-nickel cathode materials mainly occurs in the isothermal stage of the sintering process. Therefore, this study focuses on the isothermal stage of the ternary cathode material sintering process, conducting simulation studies on primary grain growth at different temperatures and times.

[0095] Step S200: Based on the primary grain distribution law, establish the grain growth mechanism formula that best matches the experimental material through mechanistic equation (MSE) matching; identify the grain growth activation energy of the high-nickel cathode material by the relationship between average grain size and temperature and time.

[0096] Based on the actual primary grain distribution pattern of high-nickel cathode materials, a grain size growth formula was established by matching the mechanistic equation MSE (mean square error). The activation energy for grain growth was identified by analyzing the relationship between average grain size and temperature and time.

[0097] To fully realize grain growth, certain physical quantities are needed to describe the change in individual grain size. The grain boundary growth rate, v, is the most intuitive variable. A fundamental assumption is first proposed: the local grain growth rate is proportional to the pressure difference caused by curvature.

[0098]

[0099] In formula (1), v is the growth rate of the grain boundary, M is the grain boundary migration coefficient, which can be regarded as the migration rate of the grain boundary; σ is the constant of the curvature transformation pressure, and ρ 1 and ρ 2Let be the principal curvature radii of the two particles opposite the grain boundary. The size of each grain will be represented by the equivalent circle radius R with the same area. In principle, the net increase in grain size can be obtained by integrating over the local grain growth rate v. The main factor affecting the local grain growth rate v is curvature. Therefore, the average grain curvature coefficients of the surrounding grains of the target grain are used. This is used to replace the curvature integral of each surrounding grain. Based on this equivalent substitution, the equivalent radius growth rate of the current grain (i.e., the grain growth rate) can be calculated. A correlation was established with the average local grain growth rate of the grains. This was proposed... The value of factor g depends on the shape of the grain. For spherical grains, it is a value proportional to the grain radius; for ordinary grains, it is a value greater than the g value of their equivalent spherical grain. Now we can write equation (2):

[0100]

[0101] In formula (2), ρ is the grain growth rate, M is the grain boundary migration coefficient, σ is the constant of curvature transformation pressure, g is a factor, and ρ 1 and ρ 2 These are the principal curvature radii of the two particles opposite each other at the grain boundary.

[0102] The increase in grain size mainly stems from the disappearance of some grains (usually smaller grains). From this simple conclusion, we can deduce that the grain growth rate for different grain sizes should have the following characteristics: assuming there is a critical grain radius R. cr When the grain size of a certain grain is greater than R cr When the grain absorbs other grains and grows, the grain growth rate is positive. However, when the grain size of a certain grain is smaller than R... cr At this point, the grain will shrink and merge into other grains, and the grain growth rate will be negative. Based on this conjecture, we can conclude that:

[0103]

[0104] In formula (3), g is a factor, ρ 1 and ρ 2 These are the principal curvature radii of two particles opposite to each other at the grain boundary, where α is a dimensionless constant, and R... cr R is the limiting grain size, and R is the equivalent grain radius.

[0105] However, simply knowing the formula for grain growth rate is not enough to construct a successful grain growth model. This is because for each different material, due to its varying properties, the specific value of Mσα is different, and their grain growth rates also differ.

[0106] Existing research has shown that Therefore, it can be achieved through actual R cr The value of Mσα is obtained to identify R. cr The data is extracted using primary grain distribution data from the sintering process of high-nickel cathode materials.

[0107] In general grain growth, the grain size distribution density function is usually considered to satisfy some fixed forms and is related to the properties of the material itself. Different materials have different grain size distribution density functions. Therefore, it is particularly important to select a suitable grain size distribution density function for high-nickel cathode materials.

[0108] The primary grain size distribution density function P(u) typically takes the following forms:

[0109] Hillert type:

[0110] Gusak, Tu type:

[0111] Mulherran type:

[0112]

[0113] In formulas (4) to (7), P(u) is the primary grain size distribution density function, K is the substitution coefficient, and τ is the relative size of the grain after normalization by the time constant u. m is the dimension, therefore we can see R cr There is a relationship between this and the grain distribution curve. Given an actual grain distribution curve F(R), divide all R values ​​of curve F(R) by R. cr Then, the scaled curve will be obtained. Therefore, for a certain grain distribution, it can be solved by formula (8), that is, when At its minimum, R cr The value of is used to obtain the limiting grain size.

[0114]

[0115] In formula (8), R cr Where is the limiting grain size, and P(u) is the theoretical grain size distribution; This is the scaled curve.

[0116] First, a scaling factor that best matches each theoretical formula is obtained by scaling the actual primary grain size distribution. Then, the mean square error between each theoretical formula and the scaled actual data is calculated. Next, the formula with the smallest mean square error is selected as the theoretical formula that best matches the actual data. Finally, the limiting grain size R is obtained by reverse engineering based on the theoretical formula. cr .

[0117] To obtain the relationship between grain growth rate and temperature T, it is necessary to obtain the activation energy Q for grain boundary migration.

[0118] First, by statistically analyzing the grain size in SEM images of isothermal sintered samples at different temperatures, the average grain size D was calculated. Then, a univariate linear regression model was established between lnD and lnt at multiple temperatures, as follows: Figure 5 As shown. By Figure 5 The linear regression results from numerical analysis yielded a grain growth index of n = 4.04. Figure 5 (a) is a univariate linear regression diagram of 1nD and lnt at 750℃ for the present invention; Figure 5 (b) is a univariate linear regression diagram of 1nD and lnt at 800℃ according to the present invention; Figure 5 (c) is a univariate linear regression diagram of 1nD and lnt at 850℃ according to the present invention.

[0119] Substitute n=4 into formula (9) to prepare for solving Q.

[0120]

[0121] In formula (9), n is the grain growth index, D is the average grain size, k0 is the initial crystal growth rate, t is time, Q is the activation energy for grain boundary migration, R is the gas constant, and T is the absolute temperature. Then, by changing the sintering temperature, a least-squares fit is performed on 1 / nD and 1 / T according to formula (9), and the result is as follows: Figure 6 As shown. Among them, Figure 6 (a) is the least squares fitting plot of 1nD and 1 / T in the present invention over a time of 3 hours; Figure 6 (b) is the least squares fitting plot of 1nD and 1 / T over a 6-hour period according to the present invention; Figure 6 (c) is the least squares fitting plot of 1nD and 1 / T under 9h time according to the present invention.

[0122] Based on the linear relationship between lnD and 1 / T, the activation energy for grain growth can be obtained, as shown in Table 1.

[0123] Table 1 Activation energy of grain growth of ternary cathode materials at different temperatures

[0124]

[0125] Step S300: Based on the grain growth mechanism formula and grain growth activation energy, obtain the grain growth parameters of the high-nickel cathode material and obtain the grain growth rate of the high-nickel cathode material at different temperatures.

[0126] Based on the grain growth mechanism formula and grain growth activation energy, grain growth parameters are obtained, thereby obtaining the grain growth rate at different temperatures. Various internal and external factors affecting the grain growth process are investigated.

[0127] Based on the primary grain size distribution data obtained in the previous experiments at different isothermal times, the limiting grain size R at different times can be obtained. cr The value, Rcr, based on the limiting grain size at different times, can be obtained through linear regression. The function of time t. Taking its derivative yields the variation function of αMσ under different isothermal times with the same initial grain distribution and a constant isothermal temperature.

[0128] Meanwhile, regarding the effect of isothermal temperature T on grain growth, research shows that temperature mainly affects grain boundary mobility M, which can be described by the thermal activation relationship of temperature:

[0129]

[0130] In formula (10), M is the grain boundary mobility, M0 is the grain boundary migration coefficient, and M0 is only related to the properties of the grain boundary itself; Q is the activation energy for grain boundary migration, k B is Boltzmann's constant, and T is the absolute temperature. After determining the activation energy at different temperatures, according to formula (11)...

[0131]

[0132] In formula (11), Let M0σα be the grain growth rate, M0σα be the set of grain growth kinetic parameters, M be the grain boundary mobility, M0 be the grain boundary migration coefficient, and Q be the activation energy for grain boundary migration, k0σα ... B R is Boltzmann's constant, T is absolute temperature; cr R is the limiting grain size, and R is the equivalent radius of the grain.

[0133] Therefore, we can obtain the following by simultaneously solving formula (2):

[0134]

[0135] In formula (12), Let M0σα be the grain growth rate, M0σα be the set of grain growth kinetic parameters, M be the grain boundary mobility, M0 be the grain boundary migration coefficient, and Q be the activation energy for grain boundary migration, k0σα ... BR is Boltzmann's constant, T is absolute temperature; cr R is the limiting grain size, and R is the equivalent radius of the grain.

[0136] Given Mσα, Q, k B And T, so the value of the grain growth kinetic parameter set M0σα can be obtained, which is a constant. Therefore, the grain growth rate at different temperatures can be obtained by formula (12).

[0137] Step S400: Based on the characteristics of the grain growth process of the high-nickel cathode material to be simulated, establish a probabilistic hedging cellular automaton, propose a grain growth rate rule, realize grain growth in the cellular automaton, propose a mass migration rule, and realize the smooth surface generated by the grain boundary surface tension.

[0138] Based on the characteristics of the grain growth process of the high-nickel cathode material to be simulated, a probabilistic hedging cellular automaton is established, and rules for grain growth rate and mass migration are proposed to construct a set of state transition rules.

[0139] A probabilistic hedging cellular automaton rule for grain growth was constructed for this process, and the grain growth during the sintering process of high-nickel cathode materials was simulated through the combined action of multiple rules. A standard quadrilateral cell space was chosen, and Mohr's neighbor was used as the cell neighbor type.

[0140] Since different grains have different orientations during grain growth, a cellular state of grain orientation is proposed. Furthermore, when initializing the cellular space, each cell is assigned an orientation value, and grain growth evolution is achieved by changing the orientation value of the cells.

[0141] From the above derivation, different grain growth rates can be obtained; however, grain growth rates cannot be directly applied to cellular automata models. Therefore, a cellular automata rule is proposed to efficiently and accurately realize the migration of grain boundaries and changes in grain orientation during grain growth. Assume the cell length is X. c When the growth rate is v, the actual time to grow a complete cell is: Given that the distance *l* = *v*1* grows at a rate *v* of 1 unit time, what is the probability that the cell will grow into a complete unit at this rate *v*? At the same time, since both grains will grow, the probability P of cell grain a is... a The probability P of reducing the number of cells b b The value is the true boundary growth rate.

[0142] However, the complete randomness of grain growth leads to burr phenomena. To address this, a boundary migration mechanism based on local curvature is proposed. The main reason real grains do not exhibit burr phenomena is that overly prominent grain boundaries become smoother due to the constraint of their surface energy. Based on this principle, the process of grain boundary surface energy constraint is transformed into material migration from prominent grain boundaries to smoother regions.

[0143] From a time-discrete perspective, the migration of matter can be decomposed into removing matter from the surface cells that need to be moved and depositing it in empty cells elsewhere on the surface. This embodiment simulates matter transport. It can be used to realize grain migration and eliminate glitch-related issues on cellular automata.

[0144] First, obtain the boundary cell C. s The location is used to mark the boundaries of the material grains, such as... Figure 9 As shown, the specific rules are as follows:

[0145]

[0146] In formula (13), For the labeled central cell, C i As the central cell, C i n For all the neighbors of the central cell.

[0147] If the central cell C i All neighbors C i n There is C i Different types of material tags M in cells c If it is an empty cell, it is marked as a boundary cell (Mk). c =1).

[0148] If the central cell C i All the neighbors are with C i If they belong to the same substance, no labeling is required (Mk). c =0).

[0149] Different migration probabilities P are determined based on the number of different cell types surrounding it. i (0 < P) i <1).

[0150] Based on the migration probability P out Move the cells out.

[0151]

[0152] In formula (14), P out Let P be the migration probability. i1 Pi2 and P i3 For the probability of migration out, The coefficients represent the position and quantity of different types of cells around the migration site. Due to mass conservation, the removed cells will deposit in vacancies near the grain surface. The cells are determined by the deposition probability P. in Deposition. The cell is represented as:

[0153]

[0154] In formula (15), P in P represents the deposition probability. j1 P j2 P j3 Equal to the migration probability. The position and number coefficients of different types of cells surrounding the migration site. These migration probabilities follow a principle. For cell positions where the number of neighboring cells is greater than half the number of molar neighbors (molar neighbors: 4), a larger migration probability is given. For cell positions where the number of neighboring cells is less than half the number of neighboring cells, a smaller migration probability is given.

[0155] Then, based on the migration probability of each boundary unit, the boundary units are randomly migrated to eliminate the glitches caused by probability transitions. A cellular automaton is constructed using the above method, and the initial state of the cellular space is established using actual data.

[0156] Step S500: Input the obtained grain growth activation energy and grain growth rate into the probabilistic hedging cellular automaton model; according to the grain growth rate rule and the mass migration rule, perform the evolution of the node particle state to obtain the probabilistic hedging cellular automaton simulation results of the oxidation reaction of high nickel cathode material; finally realize the dynamic evolution of grain growth in the sintering process of high nickel cathode material.

[0157] Based on the grain growth parameters obtained in steps S200 and S300, these parameters are input into a probabilistic hedging cellular automaton model. The evolution of the nodal particle states is then performed according to the grain growth rate rules and mass migration rules, yielding the probabilistic hedging cellular automaton simulation results for the oxidation reaction of the high-nickel cathode material. Ultimately, the dynamic evolution of grain growth during the sintering process of the high-nickel cathode material is realized.

[0158] Based on the obtained grain growth parameters, these parameters are input into a probabilistic hedging cellular automaton model. The evolution of nodal particle states is then performed according to grain growth rate and mass migration rules, yielding the probabilistic hedging cellular automaton simulation results for the oxidation reaction of high-nickel cathode materials. Ultimately, the dynamic evolution of grain growth during the sintering process of high-nickel cathode materials is realized.

[0159] To ensure the realism and effectiveness of the proposed cellular automaton model for grain growth during the sintering process of high-nickel cathode materials, the initial state of the cellular space was constructed using primary grain boundaries manually extracted from SEM images of the high-nickel cathode materials. For example... Figure 8 As shown. Among them, Figure 8 (a) is a SEM image of the high-nickel cathode material of the present invention; Figure 8 (b) is a schematic diagram of the initial state of the cell space obtained by SEM image of high-nickel cathode material in this invention.

[0160] Taking the grain growth of NCM811O as the research object, the probabilistic hedging cellular automaton model based on the grain growth rate is defined as shown in Table 2:

[0161] Table 2. Definition of the probabilistic hedging cellular automaton model based on grain growth rate.

[0162]

[0163] In Table 2, L row L col The numbers represent the horizontal and vertical cell counts in the cellular automata space, respectively. Each grain in the cellular space has a different number of orientations, which are used to label different grains. First, to visually represent the grain distribution, the boundaries between grains with different orientations are shown by black lines, and the morphological changes of grains with different orientations during sintering are analyzed. Then, a primary grain size distribution curve is obtained by statistical analysis, and the similarity between the simulation results and SEM images of actual sintered materials is quantitatively analyzed. Simultaneously, by changing the isothermal period time during sintering, grain growth results under different sintering parameters are simulated and compared with experimental results to verify the effectiveness of the cellular automata model. Figure 9 SEM and simulated images of NCM811 high-nickel cathode material synthesized at different sintering times within an isothermal range (800℃). Figure 9 As can be seen, during the evolution at 800℃, the grain size gradually increases with time, dynamically achieving grain boundary growth while retaining the original grain morphology. This is due to the mutual engulfment of grains. This is demonstrated through… Figure 9 (c) The growth process of the small grains at the center of the magnified region shows that at 6 hours, as... Figure 9 (d) The small grains have become significantly smaller. At 9h, as shown... Figure 9 (e) The small grains have been completely engulfed. From Figure 9 (f) It can be seen that the overall grain size and morphology are consistent with the morphology in the actual SEM image.

[0164] Figure 10 This shows the grain size distribution of primary grains simulated by cellular automata at different temperatures. Figure 10(a) is a grain size distribution curve of primary grains at 750℃. Figure 10 (b) is a surface plot of the primary grain size distribution at 750℃. Figure 10 (c) is a grain size distribution curve of the primary grains at 800℃. Figure 10 (d) is the surface plot of the primary grain size distribution at 800℃. Figure 10 (e) is a grain size distribution curve of the primary grains at 850℃. Figure 10 (f) is the grain size distribution surface plot of the primary grains at 850℃. Since grains can exist in countless sizes, discussing the growth status of a single grain is meaningless; therefore, the primary grain distribution curve is used for analysis. Figure 10 (a) Figure 10 (c) Figure 10 (e) As can be seen, the proposed cellular automaton for primary grain growth of high-nickel cathode materials can effectively simulate the rightward shift and broadening of the overall grain size distribution during primary grain growth, and the simulation results are consistent with the grain growth kinetics theory. After calcination at 750℃, 800℃, and 850℃ for 9 hours, the simulated average grain sizes were 376nm, 492nm, and 678nm, respectively. Furthermore, compared with the actual primary grain size distribution of NCM811 high-nickel cathode materials, the error was less than 8% during most of the grain evolution phase in the sintering process.

[0165] The simulation results and sintering experiment results show that the cellular automata model simulates the first grain growth process of high-nickel cathode material sintering, which is very close to the actual sintering process. The model can reproduce the grain growth process, which is of great significance for optimizing sintering process parameters, controlling grain growth, and obtaining high-nickel cathode materials with suitable electrochemical performance in industrial practice.

[0166] Preferably, please see Figures 1 to 10 The simulation method for the grain growth process of high-nickel cathode material provided in this embodiment includes step S200:

[0167] Step S210: Obtain the scaling factor that best matches each theoretical formula by scaling the actual primary grain size distribution.

[0168] Step S220: Calculate the mean square error between each theoretical formula and the scaled actual data.

[0169] Step S230: Select the formula with the smallest mean square error as the theoretical formula that best matches the actual data.

[0170] Step S240: Based on the theoretical formula, the limiting grain size R is obtained by reverse calculation. cr .

[0171] Further, see Figures 1 to 10 The simulation method for the grain growth process of high-nickel cathode material provided in this embodiment includes step S200, which includes:

[0172] Step S250: Calculate the average grain size D by statistically analyzing the grain size in the SEM images of isothermal sintered samples at different temperatures.

[0173] Step S260: Establish a univariate linear regression model of lnD and lnt at multiple temperatures to obtain the grain growth index n.

[0174] Step S270: Change the sintering temperature, and perform least squares fitting on lnD and 1 / T according to the following formula. Based on the linear relationship between lnD and 1 / T, the grain growth activation energy Q can be obtained.

[0175]

[0176] In formula (16), n is the grain growth index, D is the average grain size, k0 is the initial crystal growth rate, t is time, Q is the activation energy for grain boundary migration, R is the gas constant, and T is the absolute temperature.

[0177] Further, please see Figures 1 to 10 The simulation method for the grain growth process of high-nickel cathode material provided in this embodiment includes step S300:

[0178] Step S310: Based on the primary grain size distribution data obtained in the experiment under the same isothermal time, obtain the grain limiting size R at different times. cr Value; obtained through linear regression based on the grain limit size Rcr value at different times. A function of time t; for By differentiating the function with respect to time t, we obtain the variation function of αMσ under the same initial grain distribution, constant isothermal temperature, and different isothermal times.

[0179] In order to identify the grain limit size R cr The limiting grain size is extracted using primary grain distribution data from the sintering process of high-nickel cathode materials. For a given grain distribution, the limiting grain size is obtained using the following formula:

[0180]

[0181] In formula (17), R cr Where is the limiting grain size, and P(u) is the theoretical grain size distribution; This is the scaled curve.

[0182] Step S320: Simultaneously, the effect of isothermal temperature T on grain growth was studied. The study showed that temperature mainly affects grain boundary mobility M, which is described by the thermal activation relationship of temperature.

[0183]

[0184] In formula (18), M is the grain boundary mobility, M o K is the grain boundary migration coefficient; Q is the activation energy for grain boundary migration, k B is Boltzmann's constant, and T is the absolute temperature.

[0185] Step S330: After determining the activation energy at different temperatures, the grain growth rate at different temperatures is obtained according to the following formula:

[0186]

[0187]

[0188] In formulas (19) to (20), Let M0σα be the grain growth rate, M0σα be the set of grain growth kinetic parameters, M be the grain boundary mobility, M0 be the grain boundary migration coefficient, and Q be the activation energy for grain boundary migration, k0σα ... B R is Boltzmann's constant, T is absolute temperature; cr Let R be the grain size limit and R be the gas constant.

[0189] The simulation method for the grain growth process of high-nickel cathode materials provided in this embodiment, compared with the prior art, obtains the primary grain distribution law at different temperatures and times based on the grain growth data obtained from the sintering experiment of high-nickel cathode materials; based on the primary grain distribution law, a grain growth mechanism formula that best matches the experimental material is established through mechanistic equation (MSE) matching; the activation energy for grain growth of high-nickel cathode materials is identified by the relationship between average particle size and temperature and time; and the grain growth parameters of high-nickel cathode materials are obtained based on the grain growth mechanism formula and the activation energy for grain growth, thus obtaining the grain growth of high-nickel cathode materials at different temperatures. Based on the characteristics of the high-nickel cathode material grain growth process to be simulated, a probabilistic hedging cellular automaton is established, a grain growth rate rule is proposed, grain growth is realized in the cellular automaton, and a mass migration rule is proposed to realize the smooth surface generated by grain boundary surface tension. The obtained grain growth activation energy and grain growth rate are input into the probabilistic hedging cellular automaton model. The evolution of the nodal particle state is carried out according to the grain growth rate rule and the mass migration rule to obtain the probabilistic hedging cellular automaton simulation results of the oxidation reaction of high-nickel cathode material. Finally, the dynamic evolution of grain growth in the sintering process of high-nickel cathode material is realized. The simulation method for the grain growth process of high-nickel cathode materials provided in this embodiment is the first to analyze and simulate the grain growth process of high-nickel cathode materials. It not only performs relevant thermodynamic analysis on the grain growth process, but also effectively simulates the dynamic changes in the grain growth progress, thereby providing guidance for optimizing the sintering process. Based on the probabilistic hedging cellular automata model, it dynamically describes the morphological changes in the grain growth process, providing a reference for macroscopic phenomena from the microscopic process, and providing a basis for improving the sintering process, increasing the product yield, and improving the electrochemical performance of the product.

[0190] like Figure 11 As shown, Figure 11This is a functional block diagram of an embodiment of a simulation system for the grain growth process of high-nickel cathode materials provided by the present invention. In this embodiment, the simulation system for the grain growth process of high-nickel cathode materials includes a first acquisition module 10, a first establishment module 20, a second acquisition module 30, a second establishment module 40, and a third acquisition module 50. The first acquisition module 10 is used to obtain the primary grain distribution pattern at different temperatures and times based on the grain growth data obtained from the high-nickel cathode material sintering experiment. The first establishment module 20 is used to establish the grain growth mechanism formula that best matches the experimental material based on the primary grain distribution pattern through mechanistic equation (MSE) matching; and to identify the grain growth activation energy of the high-nickel cathode material through the relationship between average particle size and temperature and time. The second acquisition module 30 is used to... The first module, 40, uses formulas and grain growth activation energy to obtain grain growth parameters for high-nickel cathode materials and grain growth rates at different temperatures. The second module, 40, establishes a probabilistic hedging cellular automaton based on the characteristics of the grain growth process to be simulated, proposes grain growth rate rules, implements grain growth within the cellular automaton, and proposes mass migration rules to achieve a smooth surface generated by grain boundary surface tension. The third module, 50, inputs the obtained grain growth activation energy and grain growth rate into the probabilistic hedging cellular automaton model. Based on the grain growth rate rules and mass migration rules, the evolution of nodal particle states is performed to obtain the probabilistic hedging cellular automaton simulation results of the oxidation reaction of high-nickel cathode materials. Finally, the dynamic evolution of grain growth during the sintering process of high-nickel cathode materials is realized.

[0191] Further, see Figure 12 , Figure 12 for Figure 11 The first establishment module 20 shown in the diagram represents a functional module of a first embodiment. In this embodiment, the first establishment module 20 includes a first acquisition unit 21, a first calculation unit 22, a selection unit 23, and a back-calculation unit 24. The first acquisition unit 21 is used to obtain the scaling factor that best matches each theoretical formula by scaling the actual primary grain size distribution. The first calculation unit 22 is used to calculate the mean square error between each theoretical formula and the scaled actual data. The selection unit 23 is used to select the formula with the smallest mean square error as the theoretical formula that best matches the actual data. The back-calculation unit 24 is used to back-calculate the limiting grain size R based on the theoretical formula. cr .

[0192] Preferably, please see Figure 13 , Figure 13 for Figure 11The first establishment module shown in the second embodiment is a functional module diagram. Based on the first embodiment, the first establishment module 20 further includes a second calculation unit 25, a third calculation unit 26, and a fourth calculation unit 27. The second calculation unit 25 is used to calculate the average grain size D by statistically analyzing the grain size in the SEM images of isothermal sintered samples at different temperatures. The third calculation unit 26 is used to establish a univariate linear regression model of lnD and lnt at multiple temperatures to obtain the grain growth index n. The fourth calculation unit 27 is used to change the sintering temperature and perform least squares fitting on lnD and 1 / T according to the following formula. Based on the linear relationship between lnD and 1 / T, the grain growth activation energy Q can be obtained.

[0193]

[0194] In formula (21), n ​​is the grain growth index, D is the average grain size, k0 is the initial crystal growth rate, t is time, Q is the activation energy for grain boundary migration, R is the gas constant, and T is the absolute temperature.

[0195] Further, see Figure 14 , Figure 14 for Figure 11 The diagram shows a functional module schematic of an embodiment of the second acquisition module. In this embodiment, the second acquisition module 30 includes a second acquisition unit 31, a fifth calculation unit 32, and a sixth calculation unit 33. The second acquisition unit 31 is used to acquire the grain limit size R at different times based on the primary grain size distribution data obtained in the experiment under the same isothermal time. cr Value; based on the grain limit size R at different times. cr The value is obtained through linear regression. A function of time t; for By differentiating the function with respect to time t, we obtain the variation function of αMσ under the same initial grain distribution, constant isothermal temperature, and different isothermal times.

[0196] In order to identify the grain limit size R cr The limiting grain size is extracted using primary grain distribution data from the sintering process of high-nickel cathode materials. For a given grain distribution, the limiting grain size is obtained using the following formula:

[0197]

[0198] In formula (22), R cr Where is the limiting grain size, and P(u) is the theoretical grain size distribution; This is the scaled curve.

[0199] The fifth calculation unit 32 is used to simultaneously study the effect of isothermal temperature T on grain growth. Research shows that temperature mainly affects grain boundary mobility M, which is described by the thermal activation relationship of temperature.

[0200]

[0201] In formula (23), M is the grain boundary mobility, M0 is the grain boundary migration coefficient; Q is the activation energy for grain boundary migration, k B Boltzmann's constant is given by T, where T is the absolute temperature.

[0202] The sixth calculation unit 33 is used to obtain the grain growth rate at different temperatures according to the following formula after determining the activation energy at different temperatures:

[0203]

[0204]

[0205] In formulas (24) to (25), Let M0σα be the grain growth rate, M0σα be the set of grain growth kinetic parameters, M be the grain boundary mobility, M0 be the grain boundary migration coefficient, and Q be the activation energy for grain boundary migration, k0σα ... B R is Boltzmann's constant, T is absolute temperature; cr Let R be the grain size limit and R be the gas constant.

[0206] The simulation system for the grain growth process of high-nickel cathode materials provided in this embodiment, compared with the prior art, employs a first acquisition module 10, a first establishment module 20, a second acquisition module 30, a second establishment module 40, and a third acquisition module 50. Based on the grain growth data obtained from the high-nickel cathode material sintering experiment, it obtains the primary grain distribution law at different temperatures and times; based on the primary grain distribution law, it establishes the grain growth mechanism formula that best matches the experimental material through mechanistic equation (MSE) matching; it identifies the grain growth activation energy of the high-nickel cathode material by analyzing the relationship between average particle size and temperature and time; and it obtains the high-nickel cathode material grain growth mechanism formula and grain growth activation energy. Grain growth parameters were obtained to determine the grain growth rate of high-nickel cathode materials at different temperatures. Based on the characteristics of the grain growth process of the high-nickel cathode materials to be simulated, a probabilistic hedging cellular automaton was established, and a grain growth rate rule was proposed. Grain growth was realized in the cellular automaton, and a mass migration rule was proposed to achieve a smooth surface generated by grain boundary surface tension. The obtained grain growth activation energy and grain growth rate were input into the probabilistic hedging cellular automaton model. The evolution of the nodal particle state was carried out according to the grain growth rate rule and the mass migration rule to obtain the probabilistic hedging cellular automaton simulation results of the oxidation reaction of high-nickel cathode materials. Finally, the dynamic evolution of grain growth during the sintering process of high-nickel cathode materials was realized. The simulation system for the grain growth process of high-nickel cathode materials provided in this embodiment is the first to analyze and simulate the grain growth process of high-nickel cathode materials. It not only performs relevant thermodynamic analysis on the grain growth process, but also effectively simulates the dynamic changes in the grain growth progress, thereby providing guidance for optimizing the sintering process. Based on the probabilistic hedging cellular automata model, it dynamically describes the morphological changes in the grain growth process, providing a reference for macroscopic phenomena from the microscopic process, and providing a basis for improving the sintering process, increasing the product yield, and improving the electrochemical performance of the product.

[0207] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A method for simulating the grain growth process of a high-nickel cathode material, characterized in that, Includes the following steps: Based on the grain growth data obtained from the sintering experiment of high-nickel cathode material, the primary grain distribution law under different temperatures and times was obtained. Based on the primary grain distribution pattern, the grain growth mechanism formula that best matches the experimental material was established by matching the mechanistic equation (MSE). The activation energy for grain growth of the high-nickel cathode material was identified by the relationship between average grain size and temperature and time. Based on the grain growth mechanism formula and the grain growth activation energy, the grain growth parameters of the high-nickel cathode material are obtained, and the grain growth rate of the high-nickel cathode material at different temperatures is obtained. Based on the characteristics of the grain growth process of the high-nickel cathode material to be simulated, a probabilistic hedging cellular automaton is established, a grain growth rate rule is proposed, grain growth is realized in the cellular automaton, a mass migration rule is proposed, and a smooth surface generated by grain boundary surface tension is realized. The obtained grain growth activation energy and grain growth rate are input into the probabilistic hedging cellular automaton model; the evolution of the node particle state is carried out according to the grain growth rate rule and the mass migration rule to obtain the probabilistic hedging cellular automaton simulation results of the oxidation reaction of high nickel cathode material; finally, the dynamic evolution of grain growth in the sintering process of high nickel cathode material is realized. The steps of obtaining the grain growth parameters of the high-nickel cathode material and the grain growth activation energy based on the grain growth mechanism formula and the grain growth activation energy include: Based on the primary grain size distribution data obtained from the experiment at the same isothermal time, the values ​​at different times were obtained. Value; based on different times The value is obtained through linear regression. A function of time t; for the Differentiating the function with respect to time t yields results for the same initial grain distribution, constant isothermal temperature, and different isothermal times. Change function; Simultaneously, the effect of isothermal temperature T on grain growth was studied. The results show that temperature affects grain boundary mobility M, which is described by a thermal activation relationship with temperature: in, For grain boundary mobility, is the grain boundary migration coefficient; Q is the activation energy for grain boundary migration. It is Boltzmann's constant. Absolute temperature; After determining the activation energies at different temperatures, the grain growth rates at different temperatures are obtained using the following formula: in, This is a set of parameters for grain growth kinetics. For grain boundary mobility, is the grain boundary migration coefficient; Q is the activation energy for grain boundary migration. It is Boltzmann's constant. Absolute temperature; for R is the equivalent radius of the grain.

2. The simulation method for the grain growth process of high-nickel cathode material as described in claim 1, characterized in that, The steps of establishing the grain growth mechanism formula that best matches the experimental material based on the primary grain distribution law and by matching the mechanistic equation (MSE), and identifying the grain growth activation energy of the high-nickel cathode material by the relationship between average grain size and temperature and time, include: The scaling factor that best matches each theoretical formula is obtained by scaling the actual primary grain size distribution. Calculate the mean square error between each theoretical formula and the scaled actual data; The formula with the smallest mean square error is selected as the theoretical formula that best matches the actual data. Based on the aforementioned theoretical formula, the following can be obtained by reverse deduction: .

3. The simulation method for the grain growth process of high-nickel cathode material as described in claim 1, characterized in that, The steps of establishing the grain growth mechanism formula that best matches the experimental material based on the primary grain distribution law and by matching the mechanistic equation (MSE), and identifying the grain growth activation energy of the high-nickel cathode material by the relationship between average grain size and temperature and time, include: The average grain size D was calculated by statistically analyzing the grain size in SEM images of isothermal sintered samples at different temperatures. A univariate linear regression model of 1nD and lnt at multiple temperatures was established to obtain the grain growth index n; By changing the sintering temperature, and performing a least-squares fit on lnD and 1 / T according to the following formula, the activation energy for grain growth can be obtained based on the linear relationship between lnD and 1 / T. ; in, The grain growth index. The average grain size, The initial crystal growth rate, For time, The activation energy for grain boundary migration, The gas constant is This refers to absolute temperature.

4. The simulation method for the grain growth process of high-nickel cathode material as described in claim 1, characterized in that, Based on the primary grain size distribution data obtained in the experiment at the same isothermal time, the data at different times were obtained. Value; based on different times The value is obtained through linear regression. A function of time t; for the Differentiating the function with respect to time t yields results for the same initial grain distribution, constant isothermal temperature, and different isothermal times. In the steps of the change function, in order to identify The limiting grain size is extracted using primary grain distribution data from the sintering process of high-nickel cathode materials. For a given grain distribution, the limiting grain size is obtained using the following formula: in, for , This represents the theoretical particle size distribution. This is the scaled curve.

5. A simulation system for the grain growth process of a high-nickel cathode material, characterized in that, include: The first acquisition module (10) is used to obtain the primary grain distribution law at different temperatures and times based on the grain growth data obtained from the high-nickel cathode material sintering experiment. The first module (20) is used to establish the grain growth mechanism formula that best matches the experimental material by matching the mechanistic equation MSE according to the primary grain distribution law; and to identify the grain growth activation energy of the high-nickel cathode material by the relationship between average particle size and temperature and time. The second acquisition module (30) is used to obtain the grain growth parameters of the high-nickel cathode material according to the grain growth mechanism formula and the grain growth activation energy, and to obtain the grain growth rate of the high-nickel cathode material at different temperatures. The second module (40) is used to establish a probabilistic hedging cellular automaton based on the characteristics of the grain growth process of the high-nickel cathode material to be simulated, propose grain growth rate rules, realize grain growth in the cellular automaton, propose mass migration rules, and realize the smooth surface generated by grain boundary surface tension. The third acquisition module (50) is used to input the obtained grain growth activation energy and grain growth rate into the probabilistic hedging cellular automaton model; according to the grain growth rate rule and the mass migration rule, the evolution of the node particle state is carried out to obtain the probabilistic hedging cellular automaton simulation results of the oxidation reaction of high nickel cathode material; and finally realizes the dynamic evolution of grain growth in the sintering process of high nickel cathode material. The second acquisition module (30) includes: The second acquisition unit (31) is used to acquire the primary grain size distribution data at different times based on the primary grain size distribution data obtained in the experiment at the same isothermal time. Value; based on different times The value is obtained through linear regression. A function of time t; for the Differentiating the function with respect to time t yields results for the same initial grain distribution, constant isothermal temperature, and different isothermal times. Change function; The fifth acquisition unit (32) is used to simultaneously study the effect of isothermal temperature T on grain growth. Studies have shown that temperature affects grain boundary mobility M, which is described by the thermal activation relationship of temperature: in, For grain boundary mobility, is the grain boundary migration coefficient; Q is the activation energy for grain boundary migration. It is Boltzmann's constant. Absolute temperature; The sixth calculation unit (33) is used to obtain the grain growth rate at different temperatures according to the following formula after determining the activation energy at different temperatures: in, This is a set of parameters for grain growth kinetics. For grain boundary mobility, is the grain boundary migration coefficient; Q is the activation energy for grain boundary migration. It is Boltzmann's constant. Absolute temperature; for R is the equivalent radius of the grain.

6. The simulation system for the grain growth process of high-nickel cathode material as described in claim 5, characterized in that, The first establishment module (20) includes: The first acquisition unit (21) is used to obtain the scaling factor that best matches each theoretical formula by scaling the actual primary grain size distribution. The first calculation unit (22) is used to calculate the mean square error between each theoretical formula and the scaled actual data respectively; Select unit (23) to select the formula with the smallest mean square error as the theoretical formula that best matches the actual data; The reverse calculation unit (24) is used to reverse calculate the theoretical formula to obtain... .

7. The simulation system for the grain growth process of high-nickel cathode material as described in claim 5, characterized in that, The first establishment module (20) includes: The second calculation unit (25) is used to calculate the average grain size D by statistically analyzing the grain size in the SEM images of isothermal sintered samples at different temperatures. The third calculation unit (26) is used to establish a univariate linear regression model of 1nD and lnt at multiple temperatures and obtain the grain growth index n. The fourth calculation unit (27) is used to change the sintering temperature. According to the following formula, the least squares fit is performed on lnD and 1 / T. Based on the linear relationship between lnD and 1 / T, the grain growth activation energy can be obtained. ; in, The grain growth index. The average grain size, The initial crystal growth rate, For time, The activation energy for grain boundary migration, The gas constant is This refers to absolute temperature.

8. The simulation system for the grain growth process of high-nickel cathode material as described in claim 7, characterized in that, In the second acquisition unit (31), in order to identify The limiting grain size is extracted using primary grain distribution data from the sintering process of high-nickel cathode materials. For a given grain distribution, the limiting grain size is obtained using the following formula: in, for , This represents the theoretical particle size distribution. This is the scaled curve.

Images