Lithium battery failure mode evaluation method based on multi-physics field simulation
By constructing a multiphysics simulation model of lithium batteries, the failure modes of lithium batteries are evaluated, which solves the problems of high cost and long cycle of traditional methods, and realizes rapid and accurate evaluation and optimization design of lithium battery failure modes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUIZHOU MEILING POWER SUPPLY CO LTD
- Filing Date
- 2025-11-26
- Publication Date
- 2026-04-17
AI Technical Summary
Existing technologies struggle to quickly, simply, and effectively assess the failure modes of lithium batteries, especially under processes involving multiple physical fields. Traditional methods are costly, time-consuming, and difficult to cover extreme operating conditions.
A 3D structural model of a lithium battery is constructed using a multiphysics simulation method. Combining an electrochemical numerical model and a heat transfer model, the charging and discharging process of the lithium battery is simulated through SEI formation and lithium deposition/dissolution equations. The electrochemical performance of the composite film is predicted, and the capacity loss and aging degree of the battery are evaluated through finite element analysis.
It enables convenient and accurate assessment of lithium battery failure modes, quantitative analysis of failure causes and the mechanisms affecting electrochemical performance, and supports efficient battery design and optimization.
Smart Images
Figure CN121881702A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium battery technology, and more specifically, to a method for evaluating the failure modes of lithium batteries based on multiphysics simulation. Background Technology
[0002] Lithium-ion batteries, as energy storage devices with high energy density, long cycle life, and moderate voltage platform, are widely used in electric vehicles, portable electronic devices, and energy storage systems. However, with increasing application intensity (such as fast charging, high-rate discharging, high-temperature environments, and mechanical abuse), battery safety and reliability issues are becoming increasingly prominent. Failure modes not only affect battery life but may also lead to serious safety accidents. How to predict and assess these risks during the design phase and guide optimization is a key issue in the current battery field.
[0003] Currently, traditional failure assessment methods mainly rely on experimental approaches, which suffer from high costs, long cycles, and difficulty in covering extreme operating conditions. Furthermore, lithium batteries involve multiple coupled physical field processes, including electrochemical, thermal, and mechanical processes, leading to complex failure mechanisms and making it difficult to assess specific failure modes using conventional methods. Therefore, a technical solution is needed that can quickly, simply, and effectively assess lithium battery failure modes. Summary of the Invention
[0004] To achieve the above objectives, this application provides a lithium battery failure mode assessment method based on multiphysics simulation, comprising the following steps: Determine the 3D structure of a single soft-pack lithium-ion battery cell; Construct an electrochemical numerical model and a heat transfer model to simulate the charging and discharging process of a soft-pack lithium battery; A battery degradation model is established, and the formation of the SEI film and the state of lithium deposition / dissolution are reflected through SEI formation equations, lithium deposition / dissolution equations, and composite film equations, thereby predicting the electrochemical performance of the composite film. The electrochemical performance includes the resistivity of the composite film. Electrolyte integral and charge health status; Based on the 3D structure, a finite element analysis model is constructed to solve the electrochemical performance of the electrode charging or discharging process; the capacity loss and aging degree of the soft-pack lithium-ion battery under different operating conditions are obtained.
[0005] Among them, the electrochemical numerical model includes mass transfer equation, charge conservation equation, electrochemical reaction equation, lithium ion insertion and extraction process inside the battery electrode, lithium ion diffusion process in electrode particles and electrolyte, and electron transfer process in electrode material and current collector. The heat transfer model consists of reversible heat equations, Ohmic heat equations, polarization heat equations, convection and thermal radiation equations, and conduction equations, reflecting the heat generation, heat dissipation, and heat conduction processes during the charging and discharging of lithium batteries.
[0006] The equations illustrating the process of SEI film formation include: Voltage drop due to the formation of SEI film The calculation equation is as follows: ,in, , These are solid-state potential and liquid-state potential, respectively. To balance the electric potential, The total current density, Specific surface area For film thickness; The current density equation describing the SEI membrane side reactions is as follows: , , Where HK(1) is the dimensionless graphite expansion factor function, (1) is the transfer coefficient of the electrochemical reduction reaction. This represents the current density during the SEI membrane side reaction. (1) is an overpotential Localized accumulated charge generated for SEI formation; (1 / s) is a lumped dimensionless parameter based on the properties of SEI thin films. For solid-state potential, The liquid phase potential, This represents the equilibrium potential for the SEI film formation reaction.
[0007] The equations representing the lithium deposition / dissolution process include those representing lithium plating and lithium stripping. Among them, the equations reflecting lithium plating include: , in, , These are the charge transfer coefficients at the anode and cathode of the lithium plating reaction, respectively. It is the reaction rate formed by lithium electroplating; It is the overpotential of the lithium plating reaction; It is the equilibrium potential of the lithium battery plating layer. The concentration of the electrolyte on the negative electrode surface. For solid-state potential, This represents the liquid phase potential.
[0008] The equation representing lithium stripping is: , in, This represents the local current density during lithium stripping. , It is the charge transfer coefficient between the anode and cathode in the lithium plating reaction. It is the overpotential of the lithium stripping reaction.
[0009] Furthermore, the resistance of the composite film The calculation method is as follows: ,in, The resistance of the composite film, For the initial thickness, For the SEI film thickness, The thickness of the lithium deposition layer, The curvature factor of the SEI film. The ionic conductivity is that of the SEI membrane.
[0010] The algorithm for calculating the integral of the electrolytic liquid is as follows: ,in, Specific surface area This represents the integral number of the electrolyzed liquid.
[0011] The method for calculating the charge health status is as follows: ; in, For a healthy charge state, The initial capacity of a fresh battery. This refers to the battery capacity after cycling. Furthermore: The method for calculating the battery capacity after cycling is as follows: , Where F is the Faraday constant, The thickness of the negative electrode active material, The negative porosity, This represents the lithium concentration in the negative electrode active material after cycling. This represents the effective active area of the negative electrode. The thickness of the positive electrode active material, Porosity is the positive electrode porosity. This represents the lithium concentration in the positive electrode active material after cycling. This represents the effective active area of the positive electrode.
[0012] According to the present invention, the failure mechanism of lithium batteries can be comprehensively analyzed based on multiple factors such as electrochemistry, heat, and mechanics. Failure mode simulation can be performed by integrating multiple factors, and battery failure modes can be conveniently evaluated. The causes of battery failure and the mechanism of its impact on electrochemical performance can be quantitatively and accurately explored and analyzed, and ultimately, the efficient design and optimization of lithium batteries can be achieved. Attached Figure Description
[0013] Figure 1 This is a flowchart illustrating the steps of a lithium battery failure mode assessment method provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the computational domain of a soft-pack lithium-ion battery cell according to an embodiment of the present invention; Figure 3 This is a schematic diagram comparing the electrolytic liquid fraction at the negative electrode-diaphragm interface and the negative electrode-current collector interface according to an embodiment of the present invention. Detailed Implementation
[0014] The specific implementation of the present invention will now be described in detail with reference to the accompanying drawings.
[0015] The lithium battery failure mode process steps provided by this invention are as follows: Figure 1 As shown, it includes the following steps: Step S100: Determine the 3D structure of the soft-pack lithium-ion battery cell; the 3D structure supports different battery shapes such as cylindrical lithium batteries, soft-pack lithium batteries, and prismatic lithium batteries. The parameters related to the battery shape include the thickness, width, and length of the positive and negative electrodes, and the thickness, length, and width of the tabs.
[0016] Step S110: Construct an electrochemical numerical model and a heat transfer model to simulate the charging and discharging process of a soft-pack lithium battery; 1) The electrochemical numerical model includes mass transfer equations, charge conservation equations, and electrochemical reaction equations, which reflect the process of lithium ion insertion and extraction inside the battery electrode, the diffusion process of lithium ion in electrode particles and electrolyte, and the electron transfer process in electrode materials and current collectors.
[0017] Specifically, the diffusion equation of lithium in electrode particles is as follows: (1) (2) in, This refers to the concentration of solid lithium in the electrode particles, expressed in mol / m³. 3 ; It is the flux through the pore wall at the solid-liquid interface; It is the effective solid-phase lithium diffusion coefficient, which follows the Bruggeman relation ( The unit is m. 2 / s; It is the Bruggeman index.
[0018] The diffusion of lithium ions in the electrolyte is represented as follows: (3) in, It refers to the lithium ion concentration in the electrolyte, with units of mol / m³. 3 ; It is the effective liquid phase lithium-ion diffusion coefficient, which follows the Bruggeman relation ( The unit is m. 2 / s; It is porosity, and the unit is 1; It is the lithium-ion transfer number, with the unit being 1.
[0019] The current flowing through the solid matrix and electrolyte can be expressed as: (4) (5) (6) in, It is the effective electronic conductivity, which follows the Bruggeman relation ( ), the unit is S / m; It is the effective ionic conductivity, which follows the Bruggeman relation ( ), the unit is S / m; It is the activity factor, and the unit is 1.
[0020] The electron transfer process (i.e., charge transfer reaction) occurring at the interface between electrode particles and electrolyte is represented by the Bulller-Volmer model: (7) (8) in, It is the local volume current density on the particle surface, measured in A / m. 2 ; It is the exchange current density, and the unit is A / m. 2 ; It is the reaction rate constant, and its unit is m / s; , This refers to the maximum and surface solid-phase lithium concentration, in mol / m³. 3 ; , These are the charge transfer coefficients for the negative and positive electrodes, respectively, with a value of 0.5. It is the overpotential (the difference between the working potential and the equilibrium potential), and the unit is V; It is Faraday's constant, with a value of 96485 C / mol.
[0021] 2) The heat transfer model reflects the heat generation, heat dissipation and heat conduction processes during the charging and discharging of lithium batteries. It consists of reversible heat equation, Ohmic heat equation, polarization heat equation, convection and thermal radiation equation and heat conduction equation. Specifically, the fundamental governing equation of the heat transfer model is the energy conservation equation. Considering the internal layered structure of the battery, the reversible heat transfer (…) ), Ohm heat ( ) and polarization heat ( ) can be represented as: (9) in, For local current density, For temperature, This is the open-circuit voltage; (10) in, For solid-state potential, The liquid phase potential, The current collector potential, For solid-state current density, The liquid phase current density, The current density of the current collector; (11) in, It is the entropy heat coefficient of the positive and negative poles, with units of V / K; , , These are solid-state potential, liquid-state potential, and current collector potential, respectively, with units of V. These are the local current densities, This is an overpotential; Battery heat dissipation considers heat convection ( ) and thermal radiation ( These obey Newton's law of cooling and the law of blackbody radiation, respectively. Since the model consists of only one cell unit, which is assumed to be a random unit within the battery, the equivalent convective heat transfer coefficient and emissivity are respectively... and Where N is the number of battery cells, and based on this, heat convection ( ) and thermal radiation ( ) is represented as: (12) (13) in, It is the convective heat transfer coefficient, with units of . ; , The ambient temperature is expressed in Kelvin (K). The radiative heat transfer coefficient is expressed in units of 1000 ppm. ; This is the Stefan-Boltzmann constant, with a value of approximately 5.670374419 × 10⁻⁶. -8 The unit is .
[0022] Heat transfer inside the battery is a conduction process, represented as: (14) in, It is the battery density, measured in units of ; Specific heat capacity of the battery, in units of ; This refers to the thermal conductivity of the battery, measured in units of... ; The heat generated per unit volume of the battery is .
[0023] Step S120: Establish a battery degradation model, using the SEI formation equation, lithium deposition / dissolution equation, and composite film equation to illustrate the processes of SEI film formation, lithium deposition / dissolution, and composite film formation.
[0024] The total current density at the anode / electrolyte interface is determined by the local current density of lithium ions intercalating / deintercalating into the active particles (i... el ), local current density formed by SEI (i SEI ), local current density of lithium plating (i lp ), local current density of lithium stripping (i st Composed of ) total current density ( Specifically, it is expressed as: (15) The formation of the SEI film generates an additional voltage drop. , represented as: (16) in, , These are solid-state potential and liquid-state potential, respectively. To balance the electric potential, The total current density, Specific surface area The thickness of the SEI film; The current density equation describing the SEI membrane side reactions is as follows: (17) (18) Where HK(1) is a dimensionless graphite expansion factor function (depending on the charge state of graphite), and HK is 0 during deintercalation; (1) is the transfer coefficient of the electrochemical reduction reaction; The current density for the SEI membrane side reaction; (1) is an overpotential, and the equilibrium potential is assumed to be 0 V; (C / m)2 This refers to the localized accumulated charge generated during SEI formation; (1 / s): Lumped dimensionless parameter based on SEI thin film properties. For solid-state potential, The liquid phase potential, This represents the equilibrium potential for the SEI film formation reaction.
[0025] Lithium plating can be described using the Butler-Volmer equation as follows: (19) (20) in, , It is the charge transfer coefficient between the anode and cathode in the lithium plating reaction, with a unit of 1; It represents the reaction rate of lithium plating, measured in m / s. It is the overpotential of the lithium plating reaction, and the unit is V; It is the equilibrium potential of the lithium battery plating layer, and the unit is V; The exchange current density of lithium stripping is similar to that of lithium batteries, and is expressed as: (twenty one) in, This represents the local current density during lithium stripping. , It is the charge transfer coefficient between the anode and cathode in the lithium plating reaction. It is the overpotential of the lithium stripping reaction.
[0026] The thickness of the composite film consists of the thickness of the SEI film and the lithium deposition layer, which are calculated based on the local current density of SEI formation and lithium deposition, respectively, and are described by Fick's second law.
[0027] (twenty two) (twenty three) Furthermore, using the mixing rule approach, the electrochemical performance of the composite membrane is predicted based on the assumptions of its uniformity and periodicity: The resistance of composite films Considered SEI layer thickness and lithium deposition layer thickness The weighted average is calculated as follows: (24), among which, The thickness of the SEI layer. For the initial thickness, For the SEI film thickness, The thickness of the lithium deposition layer, The curvature factor of the SEI film. The ionic conductivity of the SEI membrane; Simultaneously, capacity decay will lead to a decrease in the integral number of the electrolyte. The calculation method for the integral number of the electrolyte is as follows: (25) in, Specific surface area Integral number of electrolyzed liquid The formula for calculating the battery capacity after cycling is as follows: (26) Where F is the Faraday constant, The thickness of the negative electrode active material, The negative porosity, This represents the lithium concentration in the negative electrode active material after cycling. This represents the effective active area of the negative electrode. The thickness of the positive electrode active material, Porosity is the positive electrode porosity. This represents the lithium concentration in the positive electrode active material after cycling. This represents the effective active area of the positive electrode. This allows us to determine the battery's state of charge health during charge-discharge cycles, namely: (27) in, For a healthy charge state, The initial capacity of the fresh battery generated for the initial design.
[0028] Step S130: Construct a finite element analysis model to calculate the integral number of the electrolyte and the charge health state during the electrode charging or discharging process, obtain the capacity loss and aging degree of the soft-pack lithium-ion battery under different operating conditions, and predict the failure mode.
[0029] This invention provides embodiments for constructing a three-dimensional finite element analysis model in finite element calculation software. Taking COMSOL Multiphysics software as an example, a model is created as follows: Figure 2 The computational domain shown is for a single soft-pack lithium-ion battery cell, which includes the negative electrode aluminum foil, negative electrode coating, separator, positive electrode coating, positive electrode aluminum sheet, negative electrode tab, and positive electrode tab. After creating a corresponding multiphysics model and meshing the computational domain, transient results can be obtained from the model, calculating the parameter states during the charge-discharge cycle.
[0030] The results obtained include parameters such as temperature, capacity, electrolyte integral number, and lithium deposition thickness of the pouch lithium-ion battery, which can be used to evaluate the battery's failure modes.
[0031] Figure 3 The electrolyte fraction at the negative electrode-separator interface (neg-sep) and negative electrode-current collector interface (neg-negCC) before and after a specified number of charge-discharge cycles (e.g., 100 cycles) is measured. As the ambient temperature increases, the electrolyte fraction at the negative electrode-separator interface and negative electrode-current collector interface within the battery increases, eventually leading to battery failure. Therefore, one of the battery failure modes under this condition can be assessed as electrolyte desiccation.
[0032] This invention addresses the problem of lithium battery failure by proposing a multiphysics simulation-based evaluation method to achieve efficient and accurate dynamic simulation of the lithium battery degradation process. Through this simulation analysis method, battery failure modes can be conveniently evaluated, and the causes of battery failure and their impact on electrochemical performance can be quantitatively and accurately investigated and analyzed, ultimately leading to the efficient design and optimization of lithium batteries.
[0033] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the present invention is not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.
Claims
1. A method for evaluating failure mode of lithium battery based on multi-physical field simulation, characterized in that, Includes the following steps: Determine the 3D structure of a single soft-pack lithium-ion battery cell; Construct an electrochemical numerical model and a heat transfer model to simulate the charging and discharging process of a soft-pack lithium battery; establishing a model of battery degradation, embodying the state of SEI film formation, lithium deposition / dissolution and predicting the electrochemical performance of the composite film through SEI formation equation, lithium deposition / dissolution equation and composite film equation; the electrochemical performance includes: the resistance of the composite film , the volume fraction of electrolyte and the state of charge health Based on the 3D structure, a finite element analysis model is constructed to solve the electrochemical performance of the electrode charging or discharging process; the capacity loss and aging degree of the soft-pack lithium-ion battery under different operating conditions are obtained.
2. The lithium battery failure mode assessment method according to claim 1, characterized in that, The electrochemical numerical model includes mass transfer equations, charge conservation equations, electrochemical reaction equations, lithium ion insertion and extraction processes inside the battery electrode, lithium ion diffusion processes in electrode particles and electrolyte, and electron transfer processes in electrode materials and current collectors. The heat transfer model consists of reversible heat equations, Ohmic heat equations, polarization heat equations, convection and thermal radiation equations, and thermal conduction equations, reflecting the heat generation, heat dissipation, and thermal conduction processes during the charging and discharging of lithium batteries.
3. The lithium battery failure mode assessment method according to claim 1, characterized in that, The equations illustrating the process of SEI film formation include: Voltage drop due to the formation of SEI film The calculation equation is as follows: ,in, , These are solid-state potential and liquid-state potential, respectively. To balance the electric potential, The total current density, The active specific surface area, The thickness of the SEI film; The current density equation describing the SEI membrane side reactions is as follows: , , Where HK(1) is the dimensionless graphite expansion factor function, (1) is the transfer coefficient of the electrochemical reduction reaction. This represents the current density during the SEI membrane side reaction. (1) is an overpotential Localized accumulated charge generated for SEI formation; (1 / s) is a lumped dimensionless parameter based on the properties of SEI thin films. For solid-state potential, The liquid phase potential, This represents the equilibrium potential for the SEI film formation reaction.
4. The lithium battery failure mode assessment method according to claim 1, characterized in that, The equations representing the lithium deposition / dissolution process include those representing lithium plating and lithium stripping. The equations reflecting lithium plating include: , in, , These are the charge transfer coefficients at the anode and cathode of the lithium plating reaction, respectively. It is the reaction rate formed by lithium electroplating; It is the overpotential of the lithium plating reaction; It is the equilibrium potential of the lithium battery plating layer, c l The concentration of the electrolyte on the negative electrode surface. For solid-state potential, This represents the liquid phase potential.
5. The lithium battery failure mode assessment method according to claim 4, characterized in that, The equation representing lithium stripping is: , in, This represents the local current density during lithium stripping. , It is the charge transfer coefficient between the anode and cathode in the lithium plating reaction. It is the overpotential of the lithium stripping reaction.
6. The lithium battery failure mode assessment method according to claim 1, characterized in that, The resistance of the composite film The calculation method is as follows: ,in, The resistance of the composite film, For the initial thickness, For the SEI film thickness, The thickness of the lithium deposition layer, The curvature factor of the SEI film. The ionic conductivity is that of the SEI membrane.
7. The lithium battery failure mode assessment method according to claim 1, characterized in that, The algorithm for calculating the integral of the electrolytic liquid is as follows: ,in, Specific surface area This represents the integral number of the electrolyzed liquid.
8. The lithium battery failure mode assessment method according to claim 1, characterized in that, The method for calculating the charge health status is as follows: ； in, For a healthy charge state, The initial capacity of a fresh battery. This represents the battery capacity after cycling; and the method for calculating the battery capacity after cycling is as follows: , Where F is the Faraday constant, The thickness of the negative electrode active material, The negative porosity, This represents the lithium concentration in the negative electrode active material after cycling. This represents the effective active area of the negative electrode. The thickness of the positive electrode active material, Porosity is the positive electrode porosity. This represents the lithium concentration in the positive electrode active material after cycling. This represents the effective active area of the positive electrode.