Graphite electrode lithium intercalation dynamic evolution process deformation-diffusion synergistic characterization method

Abstract

The invention discloses a graphite electrode lithium intercalation dynamic evolution process deformation-diffusion collaborative characterization method which comprises the following steps: establishing a graphite structure model, simulating the graphite lithium intercalation evolution process by adopting LAMMPS, and visualizing the dynamic evolution process of a graphite lithium intercalation structure from two dimensions of time and space by using OVITO; and analyzing the output mechanical and electrochemical result files of each typical phase structure. The microstructure three-dimensional deformation, the mechanical property and the electrochemical behavior of each typical phase structure of lithium-graphite are comprehensively revealed in two dimensions of space and time, and the dynamic process of embedding lithium ions into the graphite electrode is deeply analyzed by combining numerical simulation and a visualization technology; a new dynamic view angle is provided for understanding force-electrochemical coupling of the graphite electrode, and powerful theoretical support is provided for battery design and material optimization.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of lithium ion batteries, and particularly relates to a deformation-diffusion co-characterization method for a dynamic evolution process of a graphite electrode lithium intercalation. BACKGROUND

[0002] In the energy storage process, the coupling between mechanics and electrochemistry is inevitable. Taking lithium ion batteries as an example, the intercalation and deintercalation of active ions will cause significant changes in the mechanical properties of the multi-level structure of the electrode material, which in turn will affect the electrochemical process, thereby significantly affecting the force-electrochemical characteristics and energy storage performance of the battery. In addition, lithium ions intercalate and deintercalate into the interstitial gaps of the electrode material during the charging and discharging process, causing changes in the material structure. Therefore, analyzing the intercalation dynamics mechanism of lithium ions between graphite layers and revealing the force-electrochemical dynamic evolution law of the material microstructure during the charging and discharging process is crucial to improving the performance of electrode materials.

[0003] Although there have been many studies on the phase transition and microstructure changes of graphite during lithium intercalation, existing experimental techniques are generally difficult to simultaneously obtain microscale structural changes, mechanical and electrochemical information, and face challenges such as limited spatial resolution and difficulty in capturing microscale dynamics. This makes it more difficult to verify and correct the microstructure at different stages based on experimental data. Microscale calculation methods such as density functional theory (DFT) and molecular dynamics (MD) simulation have been widely used to study ion diffusion, structure evolution and reaction kinetics in lithium ion batteries. However, current microscale simulations mostly focus on static analysis, making it difficult to reflect the complex dynamic changes during lithium ion deintercalation and intercalation into graphite, and most studies are limited to constructing homogeneous structure models or single-stage compounds, failing to effectively reveal the phase transition evolution process at different lithium concentrations and its influence on electrochemical performance.

[0004] Therefore, based on molecular dynamics simulation, the application proposes a numerical simulation method for characterizing the dynamic evolution process of lithium ion intercalation into layered graphite at the atomic scale, combining LAMMPS software and ReaxFF potential functions. Through time and space dimensions, the dynamic processes such as lithium ion migration and aggregation between graphite layers are deeply discussed, and the evolution characteristics of mechanical parameters such as stress-strain relationship and fracture strength, as well as electrochemical parameters such as energy and diffusion coefficient, are analyzed. This provides a new dynamic perspective for understanding the force-electrochemical interaction of graphite electrodes. SUMMARY

[0005] The application is proposed to solve the problems in the prior art, and the purpose is to provide a deformation-diffusion co-characterization method for a dynamic evolution process of a graphite electrode lithium intercalation.

[0006] The technical scheme of the present application is: a graphite electrode lithium intercalation dynamic evolution process deformation-diffusion collaborative characterization method, comprising the following steps: A. Establish a graphite structure model using ATOMSK, and simulate the dynamic evolution process of graphite lithium intercalation using LAMMPS; B. Visualize the structure dynamic evolution process of graphite lithium intercalation from time and space dimensions using OVITO; C. Analyze the three-dimensional structure deformation, diffusion total energy and coefficient change results of the output typical phase structures LiC 27 , LiC 18 , LiC 12 , and LiC6.

[0007] Further, in step A, the graphite structure model is established, and the specific process is as follows: An ABA-stacked ten-layer graphite structure with an interlayer spacing of 3.35 Å is constructed using ATOMSK software to simulate the real configuration.

[0008] Further, in step A, LAMMPS is used to simulate the dynamic evolution process of graphite lithium intercalation, and the specific process is as follows: First, the boundary conditions are selected to avoid the influence of finite size effect on diffusion and mechanical response; Then, the potential function is selected, which is based on the potential function to simulate the structure change of different phases in the lithium intercalation process, including the bonding and breaking behavior within the layer and the diffusion process of the interlayer ions; Then, the system is relaxed to avoid structural distortion caused by mismatch between the initial configuration and stress; Finally, the dynamic lithium intercalation process is established, and representative phase structures LiC 27 , LiC 18 , LiC 12 , and LiC6 are calculated, and the results file is output.

[0009] Further, in step B, OVITO is used to visualize the structure dynamic evolution process of graphite lithium intercalation from the time dimension, and the specific process is as follows: On the time scale, the evolution process of the phase structure is understood from two angles: First, in each typical Li-GICs structure, lithium ions continuously migrate and diffuse between graphite layers, and gradually tend to be stable equilibrium state of each phase; Second, with the advancement of time, the system gradually evolves from the initial sparse lithium intercalation LiC 27 phase to the highly lithium intercalated LiC6 phase, which corresponds to the electrochemical reaction in the above lithium intercalation process, and embodies the time sequence characteristics of phase transition.

[0010] Further, step B uses OVITO to visualize the structural dynamic evolution process of lithium intercalated graphite from the spatial dimension, and the specific process is as follows: On the spatial scale, lithium ions gradually expand from the initial local distribution to multiple layers until the stable phase structure is formed under different concentrations, showing the distribution rule of lithium ions between the graphite layers. 27 The phase gradually evolves into LiC6 phase, showing the dynamic evolution process of lithium ions from sparse to dense and from local intercalation to full layer occupation.

[0011] Further, step C analyzes the three-dimensional structure deformation, diffusion total energy and coefficient change results of the output typical phase structures LiC 27 , LiC 18 , LiC 12 , LiC6, including the energy change, diffusion property and three-dimensional microstructure deformation evolution of Li-GICs.

[0012] Further, the energy change of the Li-GICs is as follows: Firstly, based on the total energy change result, the total energy change graph is obtained; Then, based on the total energy change graph, the change rule with the gradual intercalation of lithium ions is obtained; Finally, based on the energy change of Li-GICs, the energy dynamic adjustment in the process of lithium ion migration, diffusion and structure local rearrangement between the graphite layers is obtained.

[0013] Further, the diffusion property is as follows: Firstly, the mean square displacement value of Li-GICs is obtained; Then, based on the mean square displacement value, the diffusion coefficient is calculated.

[0014] Further, the three-dimensional microstructure deformation evolution is as follows: Firstly, the length change of each Li-GICs structure along the X, Y and Z directions in the intercalation process is analyzed; Then, based on the above length change, the three-dimensional microstructure deformation in the process of lithium intercalation of graphite is quantitatively characterized.

[0015] The beneficial effects of the present application are as follows: The present application comprehensively reveals the microstructure deformation, mechanical properties and electrochemical behavior of lithium-graphite typical phase structures from two dimensions of space and time.

[0016] The application can comprehensively characterize the three-dimensional structure deformation, stress-strain relationship, fracture performance and other mechanical properties of typical phase structures in the electrochemical process, analyze electrochemical parameters such as energy change and diffusion coefficient, and reveal the interaction and synergistic effect between electrochemical evolution and mechanical response through force-electrochemical synergistic characterization, thereby providing a new dynamic perspective for in-depth understanding of the force-electrochemical coupling of graphite electrodes.

[0017] The application simulates the dynamic evolution in the lithium intercalation process, accurately describes the changes of microstructure and the mutual influence of mechanical behavior and electrochemical process in the lithium intercalation process, not only provides important theoretical support for the force-electrochemical interaction of graphite electrodes, but also provides valuable basis for battery design and material optimization.

[0018] The application can be widely applied to other layered electrode materials, such as sodium storage and potassium storage systems. Through this method, key support can be provided for guiding the microstructure design of graphite negative electrodes, optimizing lithium ion diffusion channels, and improving the mechanical stability of materials, thereby promoting the development and innovation of battery technology. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the information diagram of the graphite structure and Li-GICs structure in the application; Figure 2 is the dynamic lithium intercalation process diagram in the application; Figure 3 is the total energy change of Li-GICS structure with time in the application; Figure 4 is the dynamic evolution process diagram of graphite lithium intercalation in the application, wherein (a) is the MSD value change of Li-GICS, and (b) is the diffusion coefficient change of Li-GICS; Figure 5 is the Li-GICS length and strain schematic diagram in the application, wherein (a) is the length change along the X direction, (b) is the length change along the Y direction, (c) is the length change along the Z direction, and (d) is the in-plane (x, y) and interlayer (z) strain; Figure 6 is the Li-GICS stress-strain curve diagram in the application. DETAILED DESCRIPTION

[0020] Hereinafter, the application will be described in detail with reference to the accompanying drawings and examples: As shown in the figure, the deformation-diffusion synergistic characterization method of the graphite electrode lithium intercalation dynamic evolution process comprises the following steps: Figures 1 to 6 A. Use ATOMSK to establish a graphite structure model, and use LAMMPS to simulate the dynamic evolution process of graphite lithium intercalation; A. Use ATOMSK to establish a graphite structure model, and use LAMMPS to simulate the dynamic evolution process of graphite lithium intercalation; B. Visualization of the dynamic evolution of the structure of lithium intercalated graphite from both time and space dimensions using OVITO; C. Three-dimensional structural deformation of the output typical phase structures LiC 27 , LiC 18 , LiC 12 , LiC6.

[0021] Step A: Establishing a graphite structure model, the specific process is as follows: Use ATOMSK software to construct a ten-layer graphite structure with an interlayer spacing of 3.35 Å and ABA stacking to simulate the real configuration.

[0022] Step A: Simulate the dynamic evolution of lithium intercalated graphite using LAMMPS, the specific process is as follows: First, select the boundary conditions to avoid the influence of finite size effect on diffusion and mechanical response; Then, select the potential function, which is based on the potential function to simulate the structural changes of different phases during lithium intercalation, including the bonding and breaking behavior within the layers and the diffusion process of interlayer ions; Then, system relaxation is performed to avoid structural distortion caused by mismatch between the initial configuration and stress; Finally, dynamic lithium intercalation process, establish representative phase structures LiC 27 , LiC 18 , LiC 12 , LiC6, calculate the typical phase force electrochemical information, and output the result file.

[0023] Step B: Visualization of the dynamic evolution of the structure of lithium intercalated graphite from time dimension using OVITO, the specific process is as follows: On the time scale, the evolution process of the phase structure is understood from two angles: First, in each typical Li-GICs structure, lithium ions continuously migrate and diffuse between graphite layers, and gradually tend to be stable equilibrium state of each phase; Second, with the passage of time, the system gradually evolves from the initial sparse lithium intercalated LiC 27 phase to the highly lithium intercalated LiC6 phase, which corresponds to the electrochemical reaction in the above lithium intercalation process, and embodies the time sequence characteristics of phase transition.

[0024] Step B: Visualization of the dynamic evolution of the structure of lithium intercalated graphite from space dimension using OVITO, the specific process is as follows: On the spatial scale, lithium ions gradually expand from the initial local distribution to multiple layers until stable phase structures are formed at different concentrations, showing the distribution law of lithium ions between graphite layers. From the initial LiC 27The phase gradually evolves into the LiC6 phase, showing a dynamic evolution process of lithium ions from sparse to dense and from local embedding to full layer occupation.

[0025] Step C analyzes the three-dimensional structure deformation, diffusion total energy and coefficient change results of each typical phase structure LiC 27 , LiC 18 , LiC 12 , LiC6 output in step B, including energy change, diffusion properties, and three-dimensional microstructure deformation evolution of Li-GICs.

[0026] The energy change of the Li-GICs is as follows: First, based on the total energy change result, the total energy change graph is obtained; Then, based on the total energy change graph, the change law with the gradual embedding of lithium ions is obtained; Finally, based on the energy change of Li-GICs, the energy dynamic adjustment in the process of lithium ion migration, diffusion and local structure rearrangement in the graphite interlayer is obtained.

[0027] The diffusion properties are as follows: First, the mean square displacement value of Li-GICs is obtained; Then, based on the mean square displacement value, the diffusion coefficient is calculated.

[0028] The three-dimensional microstructure deformation evolution is as follows: First, analyze the length change of each Li-GICs structure along the X, Y, and Z directions during the lithium insertion process; Then, based on the above length change, the three-dimensional microstructure deformation during the lithium insertion process of graphite is quantitatively characterized.

[0029] Specifically, the real configuration in step A is shown in Figure 1 The graphite is a hexagonal crystal, the direction perpendicular to the graphite layer is selected as the Z axis, the dimensions along the X, Y, and Z directions are 44.3Å×76.7Å×33.5Å, and it contains 12960 carbon atoms, wherein the X, Y, and Z axes correspond to the structure

[100] ,

[010] , and

[001] crystal directions, respectively, and the data file is output.

[0030] Then the output data file is processed in the Lammps open source software.

[0031] Specifically, the selection of the potential function in step A is as follows: First, the potential function reflects the description method of atomic interaction, so reasonable selection and parameterization of the potential function is an important factor to determine the accuracy and reliability of the results; Then, the ReaxFF reactive force field, based on bond-order continuity functions, can dynamically describe the formation and breaking of chemical bonds, and capture the charge transfer and local potential distribution in the lithium intercalation process through the QEq method, thus truly reproducing the electrochemical reaction behavior between lithium ions and graphite at the atomic scale to accurately simulate the structural changes of different phases, intra-layer bonding and breaking behavior, and inter-layer ion diffusion processes during the lithium intercalation process. Finally, the ReaxFF parameters of the Li-C system are selected to describe the interaction between lithium ions and the graphite lattice, and the charge balance is performed using the fix qeq command to accurately simulate the structural stability and intercalation dynamics.

[0032] Specifically, the boundary conditions in step A are selected as follows: A three-dimensional periodic boundary condition (ppp) is selected to avoid the influence of finite size effects on diffusion and mechanical response.

[0033] Specifically, the system relaxation in step A is as follows: First, the structure is thermally equilibrated to 300K using the NPT ensemble, and the system is fully relaxed to avoid structural distortion caused by mismatch between the initial configuration and stress. Then, during the dynamic loading period, a constant strain rate uniaxial strain is applied to the structure under the NVT ensemble to analyze the mechanical response process.

[0034] Specifically, the dynamic lithium intercalation process in step A is as follows: First, the lithium intercalation process into graphite is usually described in stages, and each stage is characterized by different periodic stacking sequences of intercalation and graphene layers. In the lithium ion battery lithium intercalation process, the following reactions occur sequentially inside: Li + +e - +27C→LiC 27 (Graphite-4th phase) 2LiC 27 +Li + +e - →3LiC 18 (4th phase-3rd phase) 2LiC 18 +Li + +e - →3LiC 12 (3rd phase-2nd phase) LiC 12 +Li + +e - →2LiC6(2nd phase-1st phase) Then, combining the different lattice expansion, interlayer spacing variations, and lithium distribution patterns of each typical phase, four of the most representative Li phases were established based on the graphite structure. x C6 phase structure: LiC 27 LiC 18 LiC 12 LiC6, such as Figure 1 As shown; Finally, the mechanochemical information of each typical phase is calculated and the results are output.

[0035] Specifically, step B uses OVITO to visualize the dynamic evolution of graphite lithium intercalation structure from both temporal and spatial dimensions using the data files of the typical phase structures output above, such as... Figure 2 As shown.

[0036] Specifically, in step C, based on the total energy change results of each typical phase structure output, Figure 3 The total energy change of each Li-GICs as lithium intercalation eventually reaches stability is given.

[0037] It can be seen that for each phase structure, the total energy of the system increases nonlinearly with the gradual insertion of lithium ions and reaches a peak, eventually tending to a stable state. This reflects the dynamic regulation of energy during the migration, diffusion and local rearrangement of lithium ions in the graphite layers.

[0038] Specifically, in step C Figure 4 a gives the mean square displacement values ​​of Li-GICs. Based on the output mean square displacements (MSD) of each typical phase structure, the diffusion coefficient (D) is calculated using Einstein's formula, as shown in the following equation: ; Where r is the position of the particle, t is the sampling time, and d is the dimension.

[0039] Based on the above calculation results, different stages of LiC 27 LiC 18 LiC 12 The diffusion coefficients of LiC6 and LiC6 are 2.15 × 10⁻⁶. −7 cm² / s, 2.05×10 −7 cm² / s, 1.99×10 −7 cm² / s, 1.87×10 −7 cm² / s, such as Figure 4 As shown in b. Overall, the phase diffusion coefficients at each stage are around 10. −7 cm² / s ~10 −6 The results are within the range of cm² / s, which is basically consistent with current research findings.

[0040] Specifically, in step C, the three-dimensional microstructure deformation during the lithium intercalation process of graphite is quantitatively characterized by analyzing the length changes of each Li-GICs structure along the X, Y, and Z directions. The results are as follows: Figure 5 As shown.

[0041] Application Example 1 The numerical simulation method proposed in this patent can be used to study the degradation of structural mechanical properties caused by lithium concentration. By applying a constant strain rate to each Li–GICs structure, stress-strain curves of typical phases at each stage can be obtained to analyze the mechanical properties of lithiated graphite and their evolution characteristics with lithium concentration.

[0042] Figure 6 Stress-strain curves for each phase at each stage are presented. The results show that in the initial tensile stage, the stress-strain curves of each phase exhibit a nonlinear upward trend. This reflects that the system adapts to the applied load by gradually adjusting its local structure within a small deformation range. When the strain continues to increase to the critical point, each phase structure fractures, and the stress reaches its maximum value and then rapidly decreases, exhibiting typical brittle failure characteristics.

[0043] Application Example 2 Summarizing the above-described process proposed in this invention, the mechano-electrochemical bidirectional coupling mechanism of the dynamic evolution of graphite lithiation can be revealed. During the dynamic lithiation process of graphite, electrochemical evolution and mechanical response occur simultaneously, highlighting the complex interaction between the two.

[0044] Specifically, as lithium concentration increases, the system's energy gradually rises while the diffusion coefficient gradually decreases. This reflects the evolution of lithium ion migration ability and thermodynamic stability in different phase structures at different stages. During this process, graphite exhibits nonlinearity and anisotropic deformation of its three-dimensional structure. With the continuous embedding of lithium ions, the interlayer interactions of graphite change, leading to a gradual decline in the material's mechanical properties and ultimately a significant reduction in load-bearing capacity. The mechanical evolution of graphite not only reduces the electrode's strength but also directly affects the diffusion kinetics of lithium ions by altering its structural stability, thus demonstrating a typical mechanochemical coupling effect.

[0045] From a microscopic perspective, lithium-ion intercalation alters the interlayer spacing and local electron distribution of graphite, weakening C-C bonds and interlayer van der Waals forces, directly leading to degradation of mechanical properties. Simultaneously, the three-dimensional structural deformation and internal mechanical changes induced by lithium intercalation, in turn, alter the lithium-ion diffusion channels, thereby reducing mobility. This interaction reveals a bidirectional coupling effect between mechanical and electrochemical processes. Specifically, lithium-ion diffusion is influenced by structural deformation, while the lithium intercalation process is limited by material mechanical degradation, revealing the intrinsic link between phase transitions, structural adjustments, and failure behavior, providing a comprehensive perspective for understanding the dynamic evolution of electrode materials.

[0046] This invention comprehensively reveals the microstructure deformation, mechanical properties, and electrochemical behavior of various typical lithium-graphite phase structures from both spatial and temporal dimensions. By establishing a precise model and processing it with LAMMPS software, combined with OVITO software for visualization of the evolution process and synergistic characterization of multiple mechanochemical parameters, this invention achieves precise tracking of the lithium intercalation process in graphite at the atomic scale.

[0047] This invention can comprehensively characterize the mechanical properties of typical phase structures during electrochemical processes, such as three-dimensional structural deformation, stress-strain relationship, and fracture performance. At the same time, it analyzes electrochemical parameters such as energy change and diffusion coefficient. The synergistic characterization of force and electrochemistry reveals the interaction and synergistic effect between electrochemical evolution and mechanical response, thus providing a new kinetic perspective for a deeper understanding of the force-electrochemical coupling of graphite electrodes.

[0048] This invention simulates the dynamic evolution during the lithium intercalation process, accurately describing the changes in microstructure and the interaction between mechanical behavior and electrochemical processes during lithium intercalation. It not only provides important theoretical support for the mechanochemical interaction of graphite electrodes, but also provides valuable basis for battery design and material optimization.

[0049] This invention can be widely applied to other layered electrode materials, such as sodium and potassium storage systems. This method can provide crucial support for guiding the microstructure design of graphite anodes, optimizing lithium-ion diffusion channels, and improving the mechanical stability of materials, thereby promoting the development and innovation of battery technology.

Claims

1. A deformation-diffusion synergistic characterization method for the dynamic evolution of lithium intercalation in graphite electrodes, characterized by: Includes the following steps: A. A graphite structure model was established using ATOMSK, and the dynamic evolution of graphite lithium intercalation was simulated using LAMMPS. B. Visualize the structural dynamic evolution of graphite lithium intercalation using OVITO from both temporal and spatial dimensions; C. For the typical phase structures of LiC output 27 LiC 18 LiC 12 The three-dimensional structural deformation, total diffusion energy, and coefficient changes of LiC6 were analyzed.

2. The deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes according to claim 1, characterized in that: Step A involves establishing a graphite structure model, and the specific process is as follows: A ten-layer graphite structure with an interlayer spacing of 3.35 Å and an ABA stacking pattern was constructed using ATOMSK software to simulate the real configuration.

3. The deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes according to claim 1, characterized in that: Step A uses LAMMPS to simulate the dynamic evolution of graphite lithium intercalation. The specific process is as follows: First, boundary conditions are selected to avoid the influence of finite size effects on diffusion and mechanical response; Then, the potential function is selected, and the intralayer bonding and breaking behavior and the interlayer ion diffusion process are simulated based on the potential function when the phase structure changes at different stages during the lithium intercalation process. Next, system relaxation is performed to avoid structural distortion caused by mismatch between the initial configuration and stress. Finally, the dynamic lithium intercalation process establishes a representative phase structure, LiC. 27 LiC 18 LiC 12 The algorithm calculates the mechanochemical information of typical phases of LiC6 and outputs the results file.

4. The deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes according to claim 1, characterized in that: Step B uses OVITO to visualize the dynamic evolution of graphite lithium intercalation structure over time. The specific process is as follows: The evolution of phase structure on a time scale can be understood from two perspectives: First, in each typical Li-GICs structure, lithium ions continuously migrate and diffuse between graphite layers, gradually tending towards a stable equilibrium state of each phase. Secondly, as time progresses, the system changes from an initially sparsely lithium-intercalated LiC... 27 The phase gradually evolves into a highly lithium-intercalated LiC6 phase. This process corresponds closely to the electrochemical reactions in the aforementioned lithium intercalation process, demonstrating the time-series characteristics of the phase transition.

5. The deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes according to claim 1, characterized in that: Step B uses OVITO to visualize the dynamic evolution of graphite lithium intercalation structure in a spatial dimension. The specific process is as follows: On a spatial scale, lithium ions gradually expand from their initial localized distribution to multiple layers until they form stable phase structures at different concentrations, demonstrating the distribution pattern of lithium ions between graphite layers; from the initial LiC 27 The phase gradually evolved into the LiC6 phase, exhibiting a dynamic evolution process of lithium ions from sparse to dense and from local embedding to full-layer occupation.

6. The deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes according to claim 1, characterized in that: Step C outputs typical phase structures of LiC 27 LiC 18 LiC 12 The three-dimensional structural deformation, total diffusion energy and coefficient changes of LiC6 were analyzed, including the energy changes, diffusion properties and three-dimensional deformation evolution of microstructure of Li-GICs.

7. The deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes according to claim 6, characterized in that: The energy change of the Li-GICs is as follows: First, based on the total energy change results, a total energy change diagram is obtained; Then, based on the total energy change diagram, the change pattern with the gradual embedding of lithium ions was obtained; Finally, based on the energy changes of Li-GICs, the dynamic regulation of energy during the migration, diffusion, and local structural rearrangement of lithium ions in graphite layers was obtained.

8. The deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes according to claim 6, characterized in that: The diffusion property is described in the following specific process: First, the mean square displacement values ​​of Li-GICs are obtained; Then, the diffusion coefficient is calculated based on the mean square displacement value.

9. The deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes according to claim 6, characterized in that: The specific process of the three-dimensional deformation evolution of the microstructure is as follows: First, the length changes of each Li-GICs structure along the X, Y, and Z directions during the lithium intercalation process were analyzed; Then, based on the aforementioned length changes, the three-dimensional microstructure deformation during the graphite lithium intercalation process was quantitatively characterized.

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