A method and system for optimizing the mechanical stability of solid electrolyte interfacial phases

Abstract

This invention belongs to the field of lithium-ion batteries and specifically discloses a method and system for optimizing the mechanical stability of a solid electrolyte interphase (SEI). The method includes: establishing a computational domain comprising a lithium metal electrode and a solid electrolyte interphase (SEI), wherein the SEI is attached to the upper side of the lithium metal electrode and the contact area is pre-determined to have defects; the SEI structure is a single-layer or double-layer SEI; establishing and coupling a multiphysics model within the computational domain; setting boundary conditions for the computational domain and performing mesh generation; performing simulation prediction based on the coupled multiphysics model to obtain the SEI stability under different optimization variables; and selecting the optimization variables that result in the optimal SEI stability. For a single-layer SEI, mechanical performance parameters are used as optimization variables; for a double-layer SEI, the spatial arrangement of functional layers and the layer thickness ratio are used as optimization variables. This invention can clearly define the influence of mechanical properties and microstructure on the mechanical stability of the SEI, achieving accurate prediction and optimization of SEI mechanical stability.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion batteries, and more specifically, relates to a method and system for optimizing the mechanical stability of the solid electrolyte interface phase. Background Technology

[0002] With the rapid iteration of electric vehicles, portable electronic devices, and large-scale energy storage systems, the market is placing increasingly stringent demands on the energy density, cycle life, and safety performance of lithium-ion batteries. Existing lithium-ion battery systems using graphite as the negative electrode have reached near-theoretical energy densities, making them insufficient to meet the practical needs of these high-end applications. Therefore, developing next-generation high-energy-density lithium-ion battery systems has become a significant technological barrier in the energy sector.

[0003] Lithium metal possesses an extremely high theoretical specific capacity (3860 mAh / g) and the lowest redox potential (-3.04 V vs standard hydrogen electrode), making it the most promising anode material for constructing high-energy-density lithium-ion batteries. However, lithium metal is highly chemically reactive and cannot form a thermodynamically stable coexistence system with most traditional electrolytes (including liquid electrolytes and some solid electrolytes). Upon contact, a spontaneous interfacial chemical reaction occurs. The reaction products are deposited on the surface of the lithium metal anode and gradually form a continuous solid film, namely the solid electrolyte interphase (SEI).

[0004] As a crucial interface layer between the lithium metal anode and the electrolyte, the SEI (Sediment Interlayer) directly determines the cycle performance and safety of lithium metal batteries due to its mechanical stability. If the SEI lacks sufficient mechanical strength and flexibility, it is prone to rupture during battery charging and discharging due to the drastic volume fluctuations caused by lithium metal anode deposition / dissolution. A ruptured SEI loses its protective function for the lithium metal anode, and the exposed fresh lithium metal reacts again with the electrolyte to form a new SEI. This process continuously consumes lithium metal and electrolyte, significantly reducing the battery's coulombic efficiency and energy density, and inducing lithium dendrite growth, leading to safety risks such as short circuits and thermal runaway. Therefore, the mechanical stability of the SEI is one of the core bottlenecks restricting the practical application of lithium metal batteries.

[0005] To overcome the aforementioned technical bottlenecks and improve the mechanical stability of SEIs, research has revealed that the mechanical properties of SEIs play a crucial role in regulating their mechanical stability. SEIs with appropriate mechanical properties can significantly optimize internal stress distribution and effectively suppress self-cracking. Based on this, the research field proposes a technical approach of constructing multilayer or gradient SEIs with clearly defined functional zones, aiming to precisely control the interfacial phase mechanical behavior through structural design, ultimately achieving the technical goal of long cycle life in lithium metal batteries.

[0006] However, existing research and development schemes vary significantly in electrolyte component selection, functional layer film formation process parameters, and performance characterization methods, resulting in a lack of systematic engineering understanding of the correlation mechanism between the structure, mechanical properties, and failure modes of SEIs. Crucially, the spatial arrangement of functional layers is difficult to accurately characterize the impact on interfacial stress distribution, crack propagation trajectory, and mechanical stability. This technological bottleneck severely restricts the precise preparation and large-scale application of high-performance SEIs. Therefore, improving the mechanical stability of SEIs and mitigating or suppressing mechanical failure by controlling their mechanical properties and microstructure is a key technical challenge that urgently needs to be overcome in the current SEI research and development field. Existing SEI simulation studies simplify the mechanical models, limiting them to simple flatness or surface defects, leaving almost no room for systematic control of SEI structure and mechanical properties.

[0007] Furthermore, at the theoretical simulation level, current simulation models mostly focus on electrochemical-mechanical coupling effects, failing to fully incorporate fracture behavior and thus making it difficult to realistically replicate the complete dynamic process of SEI from damage initiation and crack propagation to eventual failure. Therefore, a coupled model is needed that can accurately describe SEI failure behavior, systematically analyze mechanical properties, and understand the influence of microstructure on mechanical stability, providing technical support for the engineering design of high-performance SEIs. Summary of the Invention

[0008] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a method and system for optimizing the mechanical stability of the solid electrolyte interfacial phase (SEI). The purpose is to clarify the influence of mechanical properties and microstructure on the mechanical stability of SEI and achieve accurate prediction and optimization of SEI mechanical stability.

[0009] To achieve the above objectives, according to one aspect of the present invention, a method for optimizing the mechanical stability of a solid electrolyte interface phase is proposed, comprising the following steps: A computational domain is established that includes a lithium metal electrode and a solid electrolyte interface phase. The solid electrolyte interface phase is attached to the upper side of the lithium metal electrode, and the contact area between the lithium metal electrode and the solid electrolyte interface phase is pre-determined to have defects. The solid electrolyte interface phase structure is a single-layer SEI or a double-layer SEI. A multiphysics model is established in the computational domain, the multiphysics model is coupled, and boundary conditions are set for the computational domain and meshing is performed. Simulation predictions were performed based on a coupled multiphysics model to obtain the SEI stability under different optimization variables, and then the optimization variables for the optimal SEI stability were selected. For a single-layer SEI, mechanical performance parameters were used as optimization variables; for a double-layer SEI, the spatial arrangement of functional layers and the layer thickness ratio were used as optimization variables.

[0010] As a further preferred embodiment, the mechanical performance parameters include Young's modulus and fracture toughness; the functional layer spatial arrangement of the double-layer SEI includes the following two types: outer organic-inner inorganic, and outer inorganic-inner organic.

[0011] As a further preferred option, the multiphysics model includes the lithium dendrite phase field, concentration diffusion field, electric potential field, mechanical stress field, and fracture phase field.

[0012] As a further preferred embodiment, the lithium dendrite phase field equation is as follows:

[0013]

[0014] in, For dendritic phase field order parameters, Represents lithium metal. Indicates SEI; For time, For interface migration rate, It is a double-well function; , , These are the system's gradient density, elastic strain energy density, and fracture energy density, respectively. The reaction rate constant is... To account for the accelerating term of crack-induced dendrite growth, d The fracture phase field order parameter is used to characterize the crack. It is an interpolation function; It is a symmetry factor. It is Faraday's constant. This is an overpotential. R The gas constant is T For temperature; Lithium ion concentration, It is a fixed concentration value.

[0015] As a further preferred embodiment, the concentration diffusion field equation is as follows:

[0016] in, Lithium ion concentration, For time, For Del operators; For the effective diffusion coefficient, For electric potential, It is Faraday's constant. Let be the diffusion coefficient of lithium metal. R The gas constant is T For temperature; The density of lithium metal sites, This represents the dendritic phase field order parameter.

[0017] As a further preferred embodiment, the electric potential field equation is as follows:

[0018] in, It is Faraday's constant. The density of lithium metal sites, For dendritic phase field order parameters, For time, For Del operators, It is the electric potential; The effective conductivity is expressed using interpolation: , For lithium metal conductivity, SEI ionic conductivity, This is the interpolation function.

[0019] As a further preferred embodiment, the mechanical stress field equation is as follows:

[0020]

[0021]

[0022] in, For Del operators, and These are the stress tensor and the strain tensor, respectively. Poisson's ratio, Shear modulus Let π be the trace of the strain tensor, and 1 be the unit tensor. It is a displacement vector.

[0023] As a further preferred embodiment, the fracture phase field equation is as follows:

[0024]

[0025] in, The critical energy release rate. The parameter is the length of the lower fracture phase field. It is the historical maximum tensile strain energy function. For Del operators; d The fracture phase field order parameter is used to characterize the crack. d = 1 indicates that the crack has fully formed. d = 0 indicates that the material is intact; For effective Young's modulus, For interpolation functions, For dendritic phase field order parameters, and These are the Young's moduli of lithium and SEI, respectively. It is a degenerate function. This is a numerical stability parameter.

[0026] As a further preferred embodiment, the formula for calculating the SEI stability is:

[0027] in, is a dimensionless SEI stability index; The SEI failure time is predicted by simulation, which refers to the time elapsed until the crack in the SEI is completely penetrated. This is the longest failure time of the SEI.

[0028] According to another aspect of the present invention, a system for optimizing the mechanical stability of a solid electrolyte interface phase is provided, comprising a processor for executing the above-described method for optimizing the mechanical stability of a solid electrolyte interface phase.

[0029] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages: 1. This invention sets different optimization variables for single / double-layer SEIs. By setting different mechanical performance parameters, structural functional layer arrangement and layer thickness ratio, it simulates the dynamic evolution of mechanical failure of solid electrolyte interface phase caused by lithium dendrites based on a coupled multiphysics model. It can clarify the influence of mechanical properties and microstructure on the mechanical stability of SEI, realize the accurate prediction and optimization of SEI mechanical stability, and provide theoretical reference for experimental exploratory or trial-and-error artificial SEI design.

[0030] 2. For monolayer SEI, accurately locate the key mechanical property parameters (Young's modulus and fracture toughness) that affect the mechanical stability of SEI, and achieve targeted control of these key parameters on SEI cracking failure. Through the relationship diagram of Young's modulus-fracture toughness-SEI stability index, output the optimal SEI mechanical property design scheme, optimize and improve the mechanical properties of SEI in a targeted manner, and help to accurately prepare high-stability SEI.

[0031] 3. For double-layer SEI, through the design and simulation of the double-layer SEI structure, the system explores the regulation law of structural parameters such as functional layer arrangement and layer thickness ratio on crack propagation path and propagation rate, and accurately outputs the optimal SEI structure design scheme. This provides a practical technical basis and design strategy for the precise design of high-performance multilayer SEI structures, and breaks through the technical bottleneck of the lack of systematic theoretical guidance in the existing multilayer SEI design.

[0032] 4. This invention constructs a multiphysics model coupling the lithium dendrite phase field, electric potential field, concentration diffusion field, mechanical stress field, and fracture phase field, comprehensively covering key processes such as lithium-ion transport, lithium deposition, dendrite growth, expansion stress generation, and crack propagation. It can completely capture the entire mechanical failure evolution process of lithium dendrite-induced SEI cracking. This design overcomes the technical bottleneck of traditional models' inability to accurately describe the SEI cracking process, significantly improving the accuracy and reliability of SEI mechanical failure prediction. Attached Figure Description

[0033] Figure 1 This is a flowchart of the method for optimizing the mechanical stability of the solid electrolyte interface phase provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the geometric structure, boundary conditions, and initial value settings for predicting the mechanical stability of the solid electrolyte interface phase according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the method for optimizing the mechanical stability of the solid electrolyte interface phase provided in this embodiment of the invention. Figure 4 This is a diagram illustrating the effect of solid electrolyte interface phase cracking failure evolution calculated according to an embodiment of the present invention. Figure 5 This is a graph showing the relationship between Young's modulus, fracture toughness, and SEI stability index constructed according to an embodiment of the present invention. Figure 6 This is a comparison diagram of the functional layer arrangement, layer thickness ratio, and solid electrolyte interface phase cracking time calculated according to embodiments of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0035] This invention provides a method for optimizing the mechanical stability of a solid electrolyte interface phase, such as... Figure 1 and Figure 3 As shown, it includes the following steps: S1: Construct the computational domain and two SEI geometric models.

[0036] Specifically, a half-cell simulation structure including a lithium metal electrode and a solid electrolyte interphase (SEI) is established as the computational domain. The SEI is attached to the upper surface of the lithium metal electrode, and an initial defect (such as a semi-circular defect) is pre-defined in the contact area between the lithium metal electrode and the SEI. Symmetrical mechanical boundaries are set on both sides of the model. In this embodiment, the SEI thickness is... L Width is W Thickness of lithium metal anode D The scale is on the micrometer scale, such as Figure 2 As shown.

[0037] Furthermore, the solid electrolyte interphase (SEI) can adopt single-layer and double-layer geometric structures. Models of these two types of SEI geometric structures are constructed, and mechanical property parameters are set, including: Single-layer SEI model: The SEI as a whole adopts consistent mechanical property parameters, specifically Young's modulus. E and fracture toughness G c It is used to predict the mechanical stability of SEI and optimize mechanical parameters.

[0038] Two-layer SEI model: The SEI is constructed as a rectangular two-layer structure, and the thickness of its outer layer is defined as... l 1. The overall thickness of the double layer is l The layer thickness ratio λ is set as the ratio of the outer layer thickness to the overall thickness of the two layers (i.e., λ = ...). l 1 / l The layer thickness ratio λ is a key parameter for SEI structure control, used to characterize the thickness distribution relationship between the inner and outer layers of the SEI, and it has a decisive influence on the mechanical stability of the SEI. For bilayer SEIs, different mechanical property parameters are assigned to the inner and outer layers to characterize their differences, specifically: an outer organic-inner inorganic SEI and an outer inorganic-inner organic SEI. For organic SEIs, higher fracture toughness and lower Young's modulus are used, while for inorganic SEIs, lower fracture toughness and higher Young's modulus are used. The bilayer SEI model is used to predict the mechanical stability of bilayer SEIs and optimize structural parameters.

[0039] S2: In the two-dimensional computational domain, a multiphysics model is established, including the lithium dendrite phase field, concentration diffusion field, electric potential field, mechanical stress field, and fracture phase field. This model can simulate the failure process of SEI and be used for subsequent prediction and optimization of the mechanical stability of SEI.

[0040] Specifically, the expression for the dendritic phase field equation is:

[0041]

[0042] in, It is the dendritic phase field order parameter. Represents lithium metal. Indicates SEI, For interface migration rate, It is a double-well function. , , These represent the system's gradient density, elastic strain energy density, and fracture energy density, respectively. The reaction rate constant is the interpolation function. To satisfy the boundary conditions and , To account for the accelerating term of crack-induced dendrite growth, This is the dendrite growth adjustment coefficient. d Here, R is the sequence parameter of the fractured phase field, T is the gas constant, and T is the temperature.

[0043] The expression for the concentration diffusion field equation is:

[0044] in, Lithium ion concentration, For electric potential, This is the source term for the local concentration changes caused by dendrite growth. The density of lithium metal sites is given. To accurately describe the influence of the dendrite and SEI two-phase structure on ion transport behavior, an effective diffusion coefficient is introduced. , Let be the diffusion coefficient of lithium metal. denoted as the diffusion coefficient of SEI.

[0045] The expression for the electric potential field equation is:

[0046] Among them, effective conductivity Using interpolation: , For lithium metal conductivity, The conductivity of SEI ions.

[0047] The expression for the mechanical stress field equation is:

[0048]

[0049]

[0050] in, and These are the stress tensor and the strain tensor, respectively. Poisson's ratio, Shear modulus For Young's modulus, Represents the trace of the strain tensor. For unit tensors, It is a displacement vector.

[0051] The expression for the fracture phase field equation is:

[0052]

[0053] Among them, the fracture phase field sequence parameter d Used to characterize cracks. d = 1 indicates that the crack has fully formed. d = 0 indicates that the material is intact. The critical energy release rate. The parameter is the length of the lower fracture phase field. It is the historical maximum tensile strain energy function. and These are the Young's moduli of lithium and SEI, respectively. It is a degenerate function. This is a numerical stability parameter.

[0054] S3: Couple the multiphysics model, set boundary conditions, and mesh the computational domain.

[0055] Specifically, the lithium dendrite phase field model, concentration field model, potential field model, mechanical stress field model, and fracture phase field model are coupled to obtain a coupled model that can predict the mechanical stability of the solid electrolyte interphase (SEI). The lithium dendrite phase field is used to realize the lithium deposition behavior during charging, describing the growth of needle-like dendrites as the driving force for SEI fracture failure. The concentration diffusion field and potential field control the lithium-ion concentration distribution and battery potential distribution during lithium deposition. The mechanical stress field is used to calculate the mechanical stress generated by the volume expansion of lithium metal during deposition and to calculate the tensile elastic strain energy. The fracture phase field predicts the initiation and propagation of cracks in the SEI through the stress and strain energy of the mechanical stress field, thus demonstrating the mechanical failure of the SEI.

[0056] Accordingly, boundary conditions are set, with Dirichlet boundary conditions for the concentration field and potential field set on the upper side of the SEI: , ,in The potential applied to the upper side of the electrolyte. The lithium-ion concentration on the upper side of the SEI is specified, while the lower side of the lithium metal is electrically grounded. For the mechanical boundaries, symmetrical boundary conditions are applied to both the lithium metal and SEI sides, with the bottom side of the lithium metal side being roller-supported and the top side of the SEI side being a free boundary condition. The dendrite field and fracture phase field boundaries are both set to zero flux, i.e. , , where n is the interface normal vector.

[0057] In terms of spatial discretization, the computational domains of lithium metal and SEI are divided using triangular meshes, and the mesh is locally refined in the potential crack path region to accurately predict SEI cracking; the maximum characteristic length of the mesh in the potential crack path region is preferably one-tenth of the thickness of the phase field diffusion interface.

[0058] S4: With optimal SEI mechanical stability as the optimization objective, an optimization model is constructed; simulation predictions are performed based on a coupled multiphysics model under different optimization variables, the optimization model is solved, and the optimization variables with the best SEI stability are selected.

[0059] Specifically, the lithium dendrite phase field, concentration diffusion field, electric potential field, mechanical stress field, and fracture phase field, along with relevant boundary conditions and physical property parameters, are input into the finite element software. In one embodiment, a split solver is used to perform transient calculations on the interface phase cracking failure model; using the constructed electrochemical-mechanical-dendritic / crack phase field coupled model, the evolution of dendrite growth-induced solid electrolyte interface phase cracking failure is obtained, represented by phase field order parameters, such as... Figure 4 As shown.

[0060] Transient calculations based on a coupled multiphysics model are performed to obtain the SEI failure time under different mechanical property parameters, functional layer spatial arrangement, and layer thickness ratios of the solid electrolyte, enabling the prediction of the mechanical stability of the interface phase. This allows for a systematic analysis of the influence of different mechanical property parameters and microstructure parameters on SEI cracking failure behavior, ultimately achieving accurate prediction and targeted control of SEI cracking failure under different conditions.

[0061] Specifically, the SEI stability index is calculated as follows:

[0062] in, is a dimensionless SEI stability index; This refers to the SEI failure time. The longest failure time of the SEI is obtained through parametric scan simulation, and here it is... E Li =20 GPa, Gc =2 J / m 2 The failure time is calculated by simulation.

[0063] Specifically, the boundary conditions for the optimization model are as follows:

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075] in, This represents the potential on the lithium metal electrode side. The potential of the SEI on the side furthest from the electrode. Let n be the potential applied to the side of the SEI furthest from the electrode, and n be the interface normal vector. For effective conductivity, For a fixed concentration value, The lithium ion concentration on the side of the SEI furthest from the electrode. This refers to the lithium ion concentration within the lithium metal electrode. For the effective diffusion coefficient, This refers to the displacement of the lithium metal electrode away from the SEI side. This represents the displacement of the lithium metal side boundary. The displacement is in the normal direction. For the displacement away from the electrode side, For the displacement of the SEI side boundary, For lithium dendrite phase field order parameters The fracture phase field sequence parameter.

[0076] Furthermore, solutions were developed for both single-layer and double-layer SEI geometries, and the time for complete SEI cracking was defined as the failure time. t fThis method is used to predict and optimize the mechanical stability of SEIs with different mechanical property parameters, functional layer spatial arrangement, and layer thickness ratio. Specifically, for single-layer SEIs, different mechanical property parameters (Young's modulus and fracture toughness) are used to solve for the failure time of the SEI under different mechanical property parameters; for double-layer SEIs, different functional layer spatial arrangements and layer thickness ratios are used respectively. The solution is performed to obtain the failure time of SEI under different structures and different layer thickness ratios.

[0077] Optimizing the mechanical stability of the SEI specifically includes: For a single-layer SEI, the SEI stability index is obtained through simulation results. By adjusting different Young's modulus and fracture toughness, the relationship between the SEI stability index and Young's modulus and fracture toughness is obtained, thereby determining the optimal SEI mechanical properties and achieving SEI mechanical property optimization. Figure 5 As shown in the diagram, this relationship can guide the design of mechanical property parameters for SEI materials in industrial applications.

[0078] For bilayer SEIs, two approaches were employed: structural optimization and layer thickness ratio optimization. Different functional layer spatial arrangements were controlled, specifically including two SEI structures: an outer organic-inner inorganic layer and an outer inorganic-inner organic layer. For organic SEIs, higher fracture toughness and lower Young's modulus were used; for inorganic SEIs, lower fracture toughness and higher Young's modulus were used to optimize the functional layer spatial arrangement. Simultaneously, different layer thickness ratios were used to compare SEIs with different functional layer arrangements to obtain the optimized layer thickness ratio results, such as... Figure 6 As shown, this can guide the structural design of functional layer spatial arrangement and layer thickness ratio in double-layer or multi-layer SEI in industrial applications.

[0079] This invention also provides a solid electrolyte interface phase mechanical stability optimization system, including a processor, which is used to execute the above-described solid electrolyte interface phase mechanical stability optimization method.

[0080] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for optimizing the mechanical stability of a solid electrolyte interfacial phase, characterized in that, Includes the following steps: A computational domain is established that includes a lithium metal electrode and a solid electrolyte interface phase. The solid electrolyte interface phase is attached to the upper side of the lithium metal electrode, and the contact area between the lithium metal electrode and the solid electrolyte interface phase is pre-determined to have defects. The solid electrolyte interface phase structure is a single-layer SEI or a double-layer SEI. A multiphysics model is established in the computational domain, the multiphysics model is coupled, and boundary conditions are set for the computational domain and meshing is performed. Simulation predictions were performed based on a coupled multiphysics model to obtain the SEI stability under different optimization variables, and the optimization variables that resulted in the best SEI stability were selected. For a single-layer SEI, mechanical performance parameters were used as optimization variables; for a double-layer SEI, the spatial arrangement of functional layers and the layer thickness ratio were used as optimization variables.

2. The method for optimizing the mechanical stability of the solid electrolyte interfacial phase as described in claim 1, characterized in that, The mechanical performance parameters include Young's modulus and fracture toughness; the functional layer spatial arrangement of the double-layer SEI includes the following two types: outer organic-inner inorganic, and outer inorganic-inner organic.

3. The method for optimizing the mechanical stability of the solid electrolyte interfacial phase as described in claim 1, characterized in that, The multiphysics model includes the lithium dendrite phase field, concentration diffusion field, electric potential field, mechanical stress field, and fracture phase field.

4. The method for optimizing the mechanical stability of the solid electrolyte interfacial phase as described in claim 3, characterized in that, The lithium dendrite phase field equation is as follows: in, For dendritic phase field order parameters, Represents lithium metal. Indicates SEI; For time, For interface migration rate, It is a double-well function; , , These are the system's gradient density, elastic strain energy density, and fracture energy density, respectively. The reaction rate constant is... To account for the accelerating term of crack-induced dendrite growth, d The fracture phase field order parameter is used to characterize the crack. It is an interpolation function; It is a symmetry factor. It is Faraday's constant. This is an overpotential. R The gas constant is T For temperature; Lithium ion concentration, It is a fixed concentration value.

5. The method for optimizing the mechanical stability of the solid electrolyte interfacial phase as described in claim 3, characterized in that, The concentration diffusion field equation is as follows: in, Lithium ion concentration, For time, For Del operators; For the effective diffusion coefficient, For electric potential, It is Faraday's constant. Let be the diffusion coefficient of lithium metal. R The gas constant is T For temperature; The density of lithium metal sites, This represents the dendritic phase field order parameter.

6. The method for optimizing the mechanical stability of the solid electrolyte interfacial phase as described in claim 3, characterized in that, The electric potential field equation is as follows: in, It is Faraday's constant. The density of lithium metal sites, For dendritic phase field order parameters, For time, For Del operators, It is the electric potential; The effective conductivity is expressed using interpolation: , For lithium metal conductivity, SEI ionic conductivity, This is the interpolation function.

7. The method for optimizing the mechanical stability of the solid electrolyte interfacial phase as described in claim 3, characterized in that, The mechanical stress field equation is as follows: in, For Del operators, and These are the stress tensor and the strain tensor, respectively. Poisson's ratio, Shear modulus Let π be the trace of the strain tensor, and 1 be the unit tensor. It is a displacement vector.

8. The method for optimizing the mechanical stability of the solid electrolyte interfacial phase as described in claim 3, characterized in that, The fracture phase field equation is as follows: in, The critical energy release rate. The parameter is the length of the lower fracture phase field. It is the historical maximum tensile strain energy function. For Del operators; d The fracture phase field order parameter is used to characterize the crack. d = 1 indicates that the crack has fully formed. d = 0 indicates that the material is intact; For effective Young's modulus, For interpolation functions, For dendritic phase field order parameters, and These are the Young's moduli of lithium and SEI, respectively. It is a degenerate function. This is a numerical stability parameter.

9. The method for optimizing the mechanical stability of the solid electrolyte interfacial phase as described in any one of claims 1-8, characterized in that, The formula for calculating the SEI stability is: in, is a dimensionless SEI stability index; The SEI failure time is predicted by simulation. This is the longest failure time for the SEI.

10. A system for optimizing the mechanical stability of a solid electrolyte interfacial phase, characterized in that, Includes a processor for executing the method for optimizing the mechanical stability of the solid electrolyte interface phase as described in any one of claims 1-9.

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