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

Abstract

The application discloses a method for deforming-diffusing collaborative characterization of a lithium-embedding dynamic evolution process of a graphite electrode, and comprises the following steps: establishing a graphite structure model, simulating the evolution process of lithium embedding of the graphite by using LAMMPS, and visualizing the dynamic evolution process of the lithium embedding structure of the graphite from two dimensions of time and space by using OVITO; and analyzing the mechanical and electrochemical result files of each typical phase structure output. The application comprehensively reveals the three-dimensional deformation of the microstructure, the mechanical properties and the electrochemical behavior of each typical phase structure of lithium-graphite from two dimensions of space and time, deeply analyzes the dynamic process of lithium ion embedding into the graphite electrode by combining numerical simulation and visualization technology, provides a new dynamic perspective for understanding the force-electrochemical coupling of the graphite electrode, and provides strong theoretical support for battery design and material optimization.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion batteries, specifically relating to a deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes. Background Technology

[0002] In energy storage, the coupling effect between mechanical and electrochemical effects is unavoidable. Taking lithium-ion batteries as an example, the insertion and extraction of active ions leads to significant changes in the multi-level mechanical properties of electrode materials. These changes, in turn, affect the electrochemical process, thus significantly impacting the battery's mechanochemical characteristics and energy storage performance. Furthermore, the insertion and extraction of lithium ions into and out of the lattice gaps of electrode materials during charging and discharging cause changes in the material structure. Therefore, analyzing the intercalation kinetics of lithium ions between graphite layers and revealing the mechanochemical dynamic evolution of the material's microstructure during charging and discharging is crucial for improving electrode material performance.

[0003] Although numerous studies have explored the phase transitions and microstructural changes in graphite during lithium intercalation, current experimental techniques often struggle to simultaneously capture microscale structural changes, mechanical, and electrochemical information. They also face challenges such as limited spatial resolution and difficulty in capturing microscale dynamic processes, making the verification and correction of microstructures at different stages based on experimental data quite difficult. Microscale computational methods, such as density functional theory (DFT) and molecular dynamics (MD) simulations, have been widely used to study ion diffusion, structural evolution, and reaction kinetics in lithium-ion batteries. However, current microscale simulations largely focus on static analysis, failing to reflect the complex dynamic changes during lithium-ion deintercalation and intercalation in graphite. Furthermore, most studies are limited to constructing homogeneous structural models or single-stage compounds, failing to effectively reveal the phase transition evolution process at different lithium concentrations and its impact on electrochemical performance.

[0004] Therefore, this invention proposes a numerical simulation method based on molecular dynamics simulations, combined with LAMMPS software and the ReaxFF potential function, to systematically characterize the dynamic evolution of lithium-ion embedding in layered graphite at the atomic scale. By exploring the dynamic processes of lithium-ion migration and aggregation between graphite layers in both time and space dimensions, this method can analyze 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. This provides a new dynamic perspective for a deeper understanding of the mechano-electrochemical interaction of graphite electrodes. Summary of the Invention

[0005] This invention is proposed to address the problems existing in the prior art, and its purpose is to provide a deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes.

[0006] The technical solution of this invention is: a deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes, comprising 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.

[0007] Furthermore, in step A, a graphite structure model is established, 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.

[0008] Furthermore, step A uses LAMMPS to simulate the dynamic evolution process of graphite lithium intercalation, 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.

[0009] Furthermore, step B uses OVITO to visualize the dynamic evolution of the 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.

[0010] Furthermore, step B uses OVITO to visualize the dynamic evolution of the graphite lithium intercalation structure in a spatial dimension. The specific process is as follows: On a spatial scale, lithium ions gradually expand from an initial localized distribution to multiple layers, eventually forming 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.

[0011] Furthermore, 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.

[0012] Furthermore, 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.

[0013] Furthermore, 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.

[0014] Furthermore, the three-dimensional deformation evolution of the microstructure follows a specific process 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.

[0015] The beneficial effects of this invention are as follows: 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.

[0016] 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.

[0017] 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.

[0018] 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. Attached Figure Description

[0019] Figure 1 This is an information diagram of the graphite structure and Li-GICs structure in this invention; Figure 2 This is a diagram of the dynamic lithium intercalation process in this invention; Figure 3 This refers to the change in the total energy of the Li-GICS structure over time in this invention; Figure 4 This is a diagram showing the dynamic evolution of graphite intercalation with lithium in this invention, where (a) represents the change in the MSD value of Li-GICS and (b) represents the change in the diffusion coefficient of Li-GICS. Figure 5 This is a schematic diagram of the length and strain of Li-GICS in this invention, where (a) is the length variation along the X direction, (b) is the length variation along the Y direction, (c) is the length variation along the Z direction, and (d) is the in-plane (x, y) and interlayer (z) strain. Figure 6 This is the stress-strain curve of Li-GICS in this invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and embodiments: like Figures 1 to 6 As shown, the deformation-diffusion synergistic characterization method for the dynamic evolution of lithium intercalation in graphite electrodes 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 Three-dimensional structural deformation of LiC6.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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 an initial localized distribution to multiple layers, eventually forming stable phase structures at different concentrations, demonstrating the distribution pattern of lithium ions between graphite layers. From the initial LiC... 27The 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] Specifically, the actual configuration in step A, such as Figure 1 As shown, 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 44.3 Å × 76.7 Å × 33.5 Å, respectively, containing 12960 carbon atoms. The X, Y, and Z axes correspond to the crystal directions of the structure

[100] ,

[010] , and

[001] , respectively, and a data file is output.

[0030] The output data file is then 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 embodies the way in which interatomic interactions are described. Therefore, the appropriate selection and parameterization of the potential function is an important factor in determining the accuracy and reliability of the results. Then, the ReaxFF reactive force field, based on the bond order continuity function, can dynamically describe the formation and breaking of chemical bonds, and capture the charge transfer and local potential distribution during the lithium intercalation process through the charge equalization (QEq) method, thereby realistically reproducing the electrochemical reaction behavior between lithium ions and graphite at the atomic scale. This allows for accurate simulation of intralayer bonding and breaking behavior and interlayer ion diffusion process during the structural changes of different phases in the lithium intercalation process. Finally, the ReaxFF parameter of the Li-C system was chosen to describe the interaction between lithium ions and the graphite lattice, and the charge balance was performed using the fix qeq command to achieve accurate simulation of structural stability and intercalation dynamics.

[0032] Specifically, the selection of boundary conditions in step A is as follows: Three-dimensional periodic boundary conditions (ppp) are chosen 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 was thermally balanced to 300K using a constant temperature and pressure (NPT) ensemble to allow for sufficient relaxation of the system and avoid structural distortion caused by mismatch between the initial configuration and stress. Then, during dynamic loading, uniaxial strain at a constant strain rate is applied to the structure under an isothermal and isochoric (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 in graphene is typically described in stages, each characterized by a different periodic stacking sequence of intercalation and graphene layers. During lithium intercalation in a lithium-ion battery, the following reactions occur sequentially internally: 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 (second-order phase - first-order 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 variation of LiC6 were analyzed. 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 lithium intercalation process described above, demonstrating the time-series characteristics of the phase transition. 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.

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 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.

5. The deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes according to claim 4, 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.

6. The deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes according to claim 4, 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.

7. The deformation-diffusion synergistic characterization method for the dynamic evolution process of lithium intercalation in graphite electrodes according to claim 4, 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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