Simulation method and system for puncturing diaphragm by lithium dendrite growth

Abstract

The invention discloses a simulation method and system for penetrating a diaphragm through lithium dendrite growth, and belongs to the technical field of batteries. The method comprises the following steps: reconstructing a geometric model of the porous medium of the battery diaphragm by using a quadruple structure generation set method; deducing according to a free energy change rule and reaction kinetics to obtain a nonlinear model of order parameters changing along with time and space in a lithium dendrite growth process; calculating short-circuit current and heat in the battery through a nonlinear model, and building a short-circuit model and a heat model; a melting model is built through the short circuit model and the heat model; inputting the geometric model, the nonlinear model, the short-circuit model, the heat model and the melting model into finite element simulation software for calculation, and outputting a calculation process and a change condition of a phase field variable value in a calculation region as an image to obtain a whole process of lithium dendrites from growth to diaphragm puncture. The electric-thermal interaction of short circuit caused by lithium dendrite penetration in the lithium ion battery is quantified, and a new insight is provided for understanding a short circuit mechanism in the battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and particularly relates to a simulation method and system for the growth of lithium dendrites piercing a separator. Background Art

[0002] With the increase in the specific energy of lithium-ion batteries and the thinning of separators, the weakening of the thermal stability of lithium-ion batteries poses a serious safety threat to development. Internal short circuit (ISC) of the battery is the most common and representative safety failure mode, and is the pain point and bottleneck of battery safety. Due to the uncontrollable growth of lithium dendrites, especially under challenging operating conditions such as fast charging and low-temperature cycling, the internal short circuit caused by dendrite penetration exhibits a complex electro-thermal coupling mechanism, resisting traditional mitigation strategies, making the internal short circuit (ISC) induced by lithium dendrite penetration through the separator the most intractable and urgent problem to be solved at present.

[0003] Current research shows that a single lithium dendrite will grow around the separator. After an ISC occurs, the lithium dendrite will be damaged by the fusing effect and embedded in the positive electrode, showing a "soft short" self-healing behavior. This highlights the importance of the positive electrode and the separator in preventing the growth of lithium metal dendrites and ISC at the edge of the battery. However, there is currently a lack of a complete mechanism study on the entire process of dendrite piercing. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a simulation method and system for the growth of lithium dendrites piercing a separator, and solve the problems in the prior art.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A simulation method for the growth of lithium dendrites piercing a separator includes the following steps:

[0007] Use the quadruple structure generation set method to reconstruct the geometric model of the porous medium of the battery separator;

[0008] Derive a non-linear model of the order parameter varying with time and space during the growth of lithium dendrites according to the free energy change law and reaction kinetics;

[0009] Calculate the internal short circuit current and heat of the battery through the non-linear model, and build a short circuit model and a heat model;

[0010] Build a melting model through the short circuit model and the heat model;

[0011] Input the geometric model, non-linear model, short circuit model, heat model and melting model into finite element simulation software for calculation, and output the calculation process and the change of the phase field variable values in the calculation area as images, so as to obtain the whole process of lithium dendrites growing and piercing the separator.

[0012] Furthermore, when reconstructing the geometric model of the porous medium of the battery separator, by controlling the solid-phase growth nucleation P c , porosity n, and growth probability P d in eight directions, the formation characteristics of the porous structure of the battery separator are controlled.

[0013] Furthermore, the nonlinear model includes: a phase-field variable control equation, a lithium-ion concentration field control equation, and an electric potential field control equation;

[0014] The phase-field variable control equation is:

[0015]

[0016] h(ξ) = ξ 3 (6ξ 2 - 15ξ + 10)

[0017] where L σ and L η are the interface mobility and the interface reaction constant, respectively; κ is the gradient energy coefficient, used to represent the roughness of the electrode surface, κ = κ 0 [1 + δcos(ωθ)], δ is the strength of anisotropy, ω is the mode of anisotropy, θ is the angle between the normal vector of the interface and the axis; h(ξ) is a smooth interpolation function, is the normalized concentration of lithium ions in the electrolyte; α is the symmetry factor; F is the Faraday constant; R and T represent the ideal gas constant and temperature, respectively; η is the activation overpotential; Hg(ξ) is the double potential function;

[0018] The lithium-ion concentration field control equation is:

[0019]

[0020] D eff = D e h(ξ) + D s (1 - h(ξ))

[0021]

[0022] where D eff is the diffusion coefficient, D e is the diffusion coefficient of lithium ions in the electrode, D s is the diffusion coefficient in the electrolyte; h(ξ) is a smooth interpolation function; r i is the source term, representing the consumption of lithium ions during the electrochemical reaction process; c s is the site density of lithium metal; c 0 is the standard volume fraction of the electrolyte solution;

[0023] The potential field control equation is as follows:

[0024]

[0025] σ eff = σ e h(ξ) + σ s (1 - h(ξ))

[0026]

[0027] where σ eff represents the conductivity, σ e and σ s are the electrolyte and electrode conductivities; the source term represents the change in space charge density.

[0028] Furthermore, the short - circuit model is:

[0029]

[0030] σ d = h(ξ)σ s + (1 - h(ξ))σ df

[0031] where I short is the current density of internal short - circuit in the battery, σ d is the conductivity in the separator, φ l is the voltage across the battery; σ s is the conductivity of lithium dendrites; σ df is the conductivity of the separator.

[0032] Furthermore, the heat model is:

[0033] Q = E 0 ∫UI short dt

[0034]

[0035] ρ = h(ξ)ρ li + (1 - h(ξ))ρ s

[0036] C p = h(ξ)C li + (1 - h(ξ))C PS

[0037] where Q is the heat generated in the piercing area, E 0 is the characteristic energy density; U is the battery voltage; I shortis the internal short - circuit current density of the battery; ρ is the density distribution within the battery, where ρ li is the density of lithium, ρ s is the electrolyte density; C p is the constant - pressure heat capacity within the battery, C li is the specific heat capacity of lithium, C PS is the specific heat capacity of the electrolyte; k is the thermal conductivity within the battery, defined as k = h(ξ)R li +(1 - h(ξ))R S where R li is the thermal conductivity of lithium, R S is the thermal conductivity of the electrolyte.

[0038] Furthermore, the melting model is;

[0039]

[0040] where L σ is the interface mobility of the phase field; M(T) is the interface temperature driving term of the phase field, M > 0 represents the solidification state, M < 0 represents the melting state, and T m is the melting point of lithium.

[0041] A simulation system for lithium dendrite growth piercing the separator includes:

[0042] Geometric model construction module: Reconstruct the geometric model of the porous medium of the battery separator using the quadruple - structure generation set method;

[0043] Non - linear model construction module: Derive the non - linear model of the order parameter varying with time and space during the lithium dendrite growth process according to the free - energy change law and reaction kinetics;

[0044] Short - circuit and heat model construction module: Calculate the internal short - circuit current and heat of the battery through the non - linear model, and build the short - circuit model and heat model;

[0045] Melting model construction module: Build the melting model through the short - circuit model and heat model;

[0046] And, a simulation calculation module: Input the geometric model, non - linear model, short - circuit model, heat model, and melting model of the porous medium of the battery separator into finite - element simulation software for calculation, and output the calculation process and the change of the phase - field variable values in the calculation area as images to obtain the whole process of lithium dendrite growing and piercing the separator.

[0047] A computer storage medium stores a readable program, which can execute the above - mentioned simulation method for lithium dendrite growth piercing the separator when the program runs.

[0048] An electronic device, comprising: a processor, a memory, a communication interface, and a communication bus, wherein the processor, the memory, and the communication interface complete communication with each other through the communication bus;

[0049] The memory is used to store at least one executable instruction, and the executable instruction causes the processor to perform operations corresponding to the above-mentioned simulation method for lithium dendrite growth piercing the separator.

[0050] A computer program product, comprising computer instructions, and the computer instructions instruct a computing device to perform operations corresponding to the above-mentioned simulation method for lithium dendrite growth piercing the separator.

[0051] Advantages of the present invention:

[0052] It is difficult to observe the piercing of dendrites in the porous medium of the separator during experiments and to quantify the electro-thermal interaction caused by the penetration of lithium dendrites in a lithium-ion battery; the simulation method of the present invention accurately simulates the whole process of lithium dendrite growth piercing the separator and causing a short circuit by coupling a phase field model, a short circuit model, a thermal field model, and a melting model, quantifies the electro-thermal interaction caused by the penetration of lithium dendrites in a lithium-ion battery, and provides new insights for understanding the internal short circuit mechanism of the battery. Description of the drawings

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0054] Figure 1 It is a flow chart of the simulation method for lithium dendrite growth piercing the separator of the present invention;

[0055] Figure 2 It is a geometric model for reconstructing the porous medium of the battery separator of the present invention;

[0056] Figure 3 It is a schematic diagram of the morphology image of lithium dendrite growth piercing the separator and the internal situation of the battery. Specific embodiments

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0058] Embodiment 1

[0059] As shown Figure 1 in the figure, a simulation method for lithium dendrite growth piercing a separator includes the following steps:

[0060] S1. Use the Quasi - Random Generation Set (QSGS) method to reconstruct the geometric model of the porous medium of the battery separator;

[0061] As shown Figure 2 in the figure, the steps of reconstructing the geometric model of the porous medium of the battery separator include:

[0062] 1) Control the formation characteristics of the porous structure of the battery separator by controlling three main parameters, and the three main parameters include: solid - phase growth nucleation P c , porosity n, and growth probability P d in eight directions;

[0063] 2) The solid phase is randomly arranged in space according to a certain distribution probability P c to form solid - phase growth nuclei;

[0064] 3) The solid - phase growth nuclei continuously grow at adjacent points in eight directions according to the growth probability P d in eight directions;

[0065] 3) Repeat the operation in step 3) above until the pore phase of the battery separator reaches the given porosity n.

[0066] S2. Derive a non - linear model of the order parameter varying with time and space during the growth process of lithium dendrites according to the free - energy change law and reaction kinetics, that is: phase - field variable control equation, lithium - ion concentration - field control equation, and electric - potential - field control equation;

[0067] The total free energy G of the system consists of Helmholtz free - energy density, gradient - energy density, and electrostatic - energy density, and can be expressed as:

[0068]

[0069] where is the Helmholtz free - energy density; is the gradient - energy density related to the surface energy, κ is the gradient - energy coefficient; ρ e is the charge density, is the electrostatic potential, ξ is the order parameter; V represents the geometric volume of the system.

[0070] To describe the rapid growth of lithium dendrites at the electrode - electrolyte interface with a continuous transition and moving solid - liquid interface, in this embodiment, an order parameter is introduced to track the diffusion interface through the phase - field theory. The order parameter ξ can be used to identify two different phases (ξ = 1, ξ = 0), and the double - potential function Hg(ξ) is used to describe the electrode (ξ =

[0071] Two equilibrium states of the electrode (ξ = 0) and the electrolyte (ξ = 1) at zero overpotential.

[0072] Hg(ξ) = Wξ 2 (1 - ξ) 2

[0073] Where W is the barrier height.

[0074] The non - linear model of the order parameter varying with time and space includes: the control equation of the phase - field variable, the control equation of the lithium - ion concentration field, and the control equation of the electric potential field;

[0075] 1) Control equation of the phase - field variable

[0076] The evolution of the electrode - electrolyte interface varying with time can be described by the Allen - Cahn equation. This model assumes that the driving force for interface migration is mainly composed of two parts: the interfacial free energy and the electrode reaction affinity.

[0077]

[0078] Where L σ and L η are the interface mobility and the interface reaction constant respectively; κ is the gradient energy coefficient, used to represent the roughness of the electrode surface, κ = κ 0 [1 + δcos(ωθ)], δ is the strength of anisotropy, ω is the mode of anisotropy, θ is the angle between the normal vector of the interface and the axis; h(ξ) is a smooth interpolation function, h(ξ) = ξ 3 (6ξ 2 - 15ξ + 10); is the normalized concentration of lithium ions in the electrolyte; α is the symmetry factor; F is the Faraday constant; R and T represent the ideal gas constant and temperature respectively; η is the activation overpotential.

[0079] 2) Control equation of the lithium - ion concentration field

[0080] The Nernst - Planck equation is used to describe the diffusion transport of lithium ions. During the deposition process, the influence of electron transport is ignored, and it is described as:

[0081]

[0082] Where D eff is the diffusion coefficient, determined by the interpolation function, D eff = D e h(ξ)+D s (1 - h(ξ)), where D e is the diffusion coefficient of lithium ions in the electrode, D s is the diffusion coefficient in the electrolyte; ri is the source term, representing the consumption of lithium ions during the electrochemical reaction process. c s is the site density of lithium metal; c 0 is the standard volume fraction, i.e., the concentration, of the electrolyte solution

[0083] 3) Potential field control equation

[0084] For the potential field, assuming the system is electrically neutral, the control equation is established based on the charge conservation in the system, and the Poisson equation is used to describe the current density conservation:

[0085]

[0086] where, σ eff represents the conductivity, defined as σ eff = σ e h(ξ) + σ s (1 - h(ξ)), σ e and σ s are the conductivities of the electrolyte and the electrode; the source term represents the change in space charge density, defined as

[0087] S3, calculate the internal short - circuit current and heat of the battery through the non - linear model, and establish a short - circuit model and a heat model;

[0088] 1) Short - circuit model

[0089] When the dendrite has not grown to the separator, the separator is almost insulating, and the conductivity σ d of the separator is infinitely close to 0. When the dendrite grows and pierces the separator, the conductivity σ d of the separator will increase rapidly. Therefore, the conductivity σ d in the separator changes with the growth of the dendrite. The conductivity σ d of the separator is calculated as follows:

[0090] σ d = h(ξ)σ s + (1 - h(ξ))σ df

[0091] where, h(ξ) is a smooth interpolation function representing the growth of the dendrite; σ s is the conductivity of the lithium dendrite; σ df is the conductivity of the separator; after the dendrite pierces the separator, the battery undergoes an internal short - circuit, and the current density I short of the internal short - circuit of the battery is described as:

[0092]

[0093] where, σd is the conductivity within the separator; φ l is the voltage across both sides of the battery.

[0094] 2) Heat model

[0095] After internal short circuit occurs in the battery, the heat Q generated in the punctured area is described as follows:

[0096] Q = E 0 ∫UI short dt

[0097] where E 0 is the characteristic energy density; U is the battery voltage; I short is the internal short circuit current density of the battery. Then, the temperature change of the puncturing dendrite is calculated based on the heat, and the calculation formula is as follows:

[0098]

[0099] where ρ is the density distribution within the battery, defined as ρ = h(ξ)ρ li +(1 - h(ξ))ρ s , where ρ li is the density of lithium, ρ s is the density of the electrolyte; C p is the constant pressure heat capacity within the battery, defined as C p = h(ξ)C li +(1 - h(ξ))C PS , where C li is the specific heat capacity of lithium, C PS is the specific heat capacity of the electrolyte; κ is the thermal conductivity within the battery, defined as κ = h(ξ)R li +(1 - h(ξ))R S , where R li is the thermal conductivity of lithium, R S is the thermal conductivity of the electrolyte.

[0100] S4. Build a melting model through the short circuit model and the heat model;

[0101] After the lithium dendrite punctures the separator, a large amount of heat is generated due to the internal short circuit in the battery, and the temperature rises rapidly exceeding the melting point of lithium, resulting in its own melting; the melting of the dendrite is a process in which the phase changes due to the change when the temperature within the short circuit dendrite in the battery exceeds the melting point of lithium under the condition that it was originally in a stable growth state, which leads to the migration of its solid-liquid interface to increase the liquid phase volume, thereby triggering the local or overall melting of the crystal. The coupled control equations of the phase field and the temperature field in this model are expressed as follows:

[0102]

[0103] where, Lσ is the interface mobility of the phase field; M(T) is the interface temperature driving term of the phase field. M>0 represents the solidification state, and M<0 represents the melting state, which is expressed as follows:

[0104]

[0105] where T m is the melting point of lithium; finally, the coupled control equations of the phase field and the temperature field in the model are written in the following form:

[0106]

[0107] After the coupling of the phase field and the temperature field is completed, it is incorporated into the phase field model, which is expressed as follows:

[0108]

[0109] S5. Input the geometric model of the porous medium of the battery separator in S1, the nonlinear model in S2, the internal short-circuit model, the heat model in S3, and the melting model in S4 into the finite element simulation software for calculation, and output the calculation process and the change of the phase field variable values in the calculation area as images to obtain the whole process of lithium dendrite growing and piercing the separator;

[0110] In this embodiment, the finite element simulation software is specifically: Comsol.

[0111] In order to speed up the calculation, standardized numbers are used for calculation, boundary conditions, initial conditions, calculation step size and calculation time are set, and transient solution of the equations is carried out;

[0112] Output the whole calculation process and the change of the phase field variable ξ, the short-circuit model variable I, and the heat model variable T values in the whole calculation area as images, as Figure 3 shown, that is, to obtain the whole process of lithium dendrite growing on the negative electrode surface of the lithium battery, piercing the separator, causing internal short circuit of the battery and triggering internal reactions of the battery.

[0113] From Figure 3 it can be seen that from top to bottom are the dendrite growth diagram, the internal short-circuit diagram of the battery, and the internal temperature diagram of the battery. Before the dendrite pierces the separator, there is no short-circuit situation in the battery, and the internal short-circuit diagram and the internal temperature diagram of the battery remain in the initial state. When the dendrite pierces the separator, a short-circuit phenomenon occurs inside the battery, and a large amount of current passes through the area where the dendrite pierces. The I short can be observed through the internal short-circuit diagram of the battery. Due to a large amount of Joule heat generated by the short circuit, the increase of the internal temperature of the battery is calculated through the thermal field model, and the internal temperature diagram of the battery is displayed in real time. As the temperature continues to rise and exceeds the melting point of the lithium dendrite, a melting phenomenon occurs, which can be directly observed from the dendrite growth diagram.

[0114] Based on a similar inventive concept, an embodiment of the present invention further provides a computer storage medium storing a readable program which, when running, can execute the above-mentioned simulation method for lithium dendrite growth piercing a separator.

[0115] Based on a similar inventive concept, an embodiment of the present invention provides an electronic device, including: a processor, a memory, a communication interface, and a communication bus. The processor, the memory, and the communication interface complete communication with each other through the communication bus;

[0116] The memory is used to store at least one executable instruction, and the executable instruction causes the processor to execute the operations corresponding to the above-mentioned simulation method for lithium dendrite growth piercing a separator.

[0117] Based on a similar inventive concept, an embodiment of the present invention further provides a computer program product including computer instructions, and the computer instructions instruct a computing device to execute the operations corresponding to the above-mentioned simulation method for lithium dendrite growth piercing a separator.

[0118] Embodiment 2

[0119] Based on the simulation method for lithium dendrite growth piercing a separator proposed in Embodiment 1, in this embodiment, a simulation system for lithium dendrite growth piercing a separator is proposed, including:

[0120] Geometric model construction module: reconstruct the geometric model of the porous medium of the battery separator using the quadruple structure generation set method;

[0121] Nonlinear model construction module: derive a nonlinear model of the order parameter varying with time and space during the growth process of lithium dendrites according to the free energy change law and reaction kinetics;

[0122] Short circuit and heat model construction module: calculate the internal short circuit current and heat of the battery through the nonlinear model, and build a short circuit model and a heat model;

[0123] Melting model construction module: build a melting model through the short circuit model and the heat model;

[0124] And a simulation calculation module: input the geometric model, nonlinear model, short circuit model, heat model, and melting model of the porous medium of the battery separator into finite element simulation software for calculation, and output the calculation process and the change of the phase field variable values in the calculation area as images to obtain the whole process of lithium dendrite growing and piercing the separator.

[0125] The method of the present invention can be implemented in hardware, firmware, or be implemented as software or computer code that can be stored in a recording medium (such as a CDROM, RAM, floppy disk, hard disk, or magneto-optical disk), or be implemented as computer code that is originally stored in a remote recording medium or a non-transitory machine-readable medium and downloaded through a network and will be stored in a local recording medium, so that the method described herein can be stored on such a software process on a recording medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware (such as an ASIC or FPGA). It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component (such as RAM, ROM, flash memory, etc.) that can store or receive software or computer code, and when the software or computer code is accessed and executed by the computer, the processor, or the hardware, the method described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the method shown herein, the execution of the code converts the general-purpose computer into a dedicated computer for executing the method shown herein.

[0126] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A method for simulating lithium dendrite growth piercing a diaphragm, characterized in that: The following steps are involved: The geometric model of battery separator porous media was reconstructed using the quadruple structure generation set method; According to the free energy change law and reaction kinetics, a nonlinear model of the order parameters changing with time and space in the process of lithium dendrite growth is derived; Calculate the short-circuit current and heat inside the battery through the nonlinear model, and build a short-circuit model and a heat model; Building a melting model through the short circuit model and the heat model; The geometric model, nonlinear model, short circuit model, thermal model and melting model are input into finite element simulation software for calculation, and the calculation process and the change of the phase field variable value in the calculation area are output as an image to obtain the whole process of lithium dendrites from growth to piercing the diaphragm.

2. The method for simulating lithium dendrite growth piercing a diaphragm according to claim 1, characterized in that: When reconstructing the geometric model of the cell membrane porous medium, the solid phase growth nucleation P c , porosity n and growth probability P in 8 directions d , to control the formation characteristics of the porous structure of the battery separator.

3. The method for simulating lithium dendrite growth piercing a diaphragm according to claim 1, characterized in that: The nonlinear model includes: phase field variable control equation, lithium ion concentration field control equation and electric potential field control equation; The phase field variable control equation is: h(ξ)=ξ 3 (6x) 2 -15x+10) Among them, L σ and L η are the interface mobility and interface reaction constant respectively; κ is the gradient energy coefficient, which is used to represent the roughness of the electrode surface, κ=κ0[1+δcos(ωθ)], δ is the intensity of anisotropy, ω is the anisotropy mode, θ is the angle between the normal vector of the interface and the axis; h(ξ) is a smooth interpolation function, is the normalized concentration of lithium ions in the electrolyte; α is the symmetry factor; F is the Faraday constant; R and T represent the ideal gas constant and temperature, respectively; η is the activation overpotential; Hg(ξ) is the bipotential function; The lithium ion concentration field control equation is: D eff =D e h(ξ)+D s (1-h(ξ)) Among them, D eff is the diffusion coefficient, D e is the diffusion coefficient of lithium ions in the electrode, D s is the diffusion coefficient in the electrolyte; h(ξ) is a smooth interpolation function; r i is the source term, which represents the consumption of lithium ions during the electrochemical reaction; c s is the site density of lithium metal; c0 is the standard volume fraction of the electrolyte solution; The potential field control equation is: s eff =s e h(ξ)+σ s (1-h(ξ)) Among them, σ eff represents the conductivity, σ e and σ s is the conductivity of the electrolyte and the electrode; the source term Represents the change in space charge density.

4. A method for simulating lithium dendrite growth piercing a diaphragm according to claim 3, characterized in that: The short-circuit model is: s d =h(ξ)σ s +(1-h(ξ))σ df Among them, I short is the current density of the internal short circuit of the battery, σ d is the conductivity in the diaphragm, φ l is the voltage on both sides of the battery; σ s is the conductivity of lithium dendrite; σ df is the conductivity of the diaphragm.

5. A method for simulating lithium dendrite growth piercing a diaphragm according to claim 4, characterized in that: The thermal model is: Q=E0∫UI short dt ρ=h(ξ)ρ li +(1-h(ξ))ρ s C p =h(ξ)C li +(1-h(ξ))C PS Where Q is the heat generated in the puncture area, E0 is the characteristic energy density; U is the battery voltage; I short is the short-circuit current density inside the battery; ρ is the density distribution inside the battery, where ρ li is the density of lithium, ρ s is the electrolyte density; C p is the constant pressure heat capacity of the battery, C li is the specific heat capacity of lithium, C PS is the specific heat capacity of the electrolyte; k is the thermal conductivity in the battery, defined as k = h(ξ)R li +(1-h(ξ))R S , R li is the thermal conductivity of lithium, R S is the thermal conductivity of the electrolyte.

6. A method for simulating lithium dendrite growth piercing a diaphragm according to claim 5, characterized in that: The melting model is: Among them, L σ is the interface mobility of the phase field; M(T) is the interface temperature driving term of the phase field, M>0 indicates the solidified state, M<0 indicates the melted state, T m is the melting point of lithium.

7. A simulation system for lithium dendrite growth piercing a diaphragm, characterized in that: include: Geometric model building module: Use the quadruple structure generation set method to reconstruct the geometric model of battery separator porous media; Nonlinear model building module: Based on the free energy change law and reaction kinetics, a nonlinear model of the order parameters changing with time and space in the process of lithium dendrite growth is derived; Short circuit and heat model building module: calculate the short circuit current and heat inside the battery through the nonlinear model, and build a short circuit model and a heat model; Melting model building module: build melting model through short circuit model and heat model; And, the simulation calculation module: the geometric model, nonlinear model, short circuit model, thermal model and melting model of the battery diaphragm porous medium are input into the finite element simulation software for calculation, and the calculation process and the change of the phase field variable value in the calculation area are output as an image to obtain the whole process of lithium dendrites from growth to piercing the diaphragm.

8. A computer storage medium storing a readable program, characterized in that: When the program is running, it can execute the simulation method of lithium dendrite growth piercing the separator as described in any one of claims 1-6.

9. An electronic device, characterized in that: include: A processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other via the communication bus; The memory is used to store at least one executable instruction, and the executable instruction enables the processor to perform operations corresponding to a simulation method of lithium dendrite growth piercing a diaphragm as described in any one of claims 1-6.

10. A computer program product comprising computer instructions, characterized in that: The computer instructions instruct the computing device to perform operations corresponding to the simulation method of lithium dendrite growth piercing a diaphragm as described in any one of claims 1-6.

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