CN-122021014-A - Electrothermal coupling simulation modeling method and system for silicon-carbon negative electrode high specific energy lithium battery

CN122021014ACN 122021014 ACN122021014 ACN 122021014ACN-122021014-A

Abstract

The application provides a simulation modeling method and a system for electrothermal coupling of a silicon-carbon negative electrode high specific energy lithium battery, wherein the method comprises the steps of constructing a geometric model of the battery to be simulated; the method comprises the steps of establishing an electrochemical control equation set based on a porous electrode theory and a pseudo three-dimensional model and a thermal model control equation based on an energy conservation principle, setting materials for each region, setting adjustable input parameters required by the model, performing bidirectional coupling on the electrochemical control equation set and the thermal model control equation through an Arrhenius equation, performing grid subdivision, solving through a transient solver, performing iterative calculation through judging convergence, and finally outputting simulation results of a temperature field, potential distribution and lithium ion concentration distribution. The application provides a high-precision virtual analysis tool, which can finely simulate the bidirectional coupling process of the electrochemical and thermal behaviors in the battery and provides theoretical support for structural design and safety evaluation of the high-specific-energy battery.

Inventors

HAN XIAOPENG
FU XIAORUI
LI JINYANG
DONG QIUJIANG
LIU CHENGWEI
GUO SHAOPENG

Assignees

天津大学

Dates

Publication Date: 20260512
Application Date: 20260128

Claims (10)

1. The electrothermal coupling simulation modeling method for the silicon-carbon negative electrode high specific energy lithium battery is characterized by comprising the following steps of: step S1, constructing a geometric model of a high specific energy lithium battery to be simulated based on battery parameters; s2, adding a physical field of the lithium ion battery into the geometric model to establish an electrochemical control equation set based on a porous electrode theory and a pseudo three-dimensional model; S3, adding a solid heat transfer physical field into the geometric model to establish a thermal model control equation based on an energy conservation principle; step S4, setting corresponding materials for a positive electrode area, a diaphragm area and a negative electrode area in the geometric model respectively; S5, setting adjustable input parameters required by the electrochemical control equation set and the thermal model control equation; Step S6, based on the value of the adjustable input parameter, the electrochemical control equation set and the thermal model control equation are bidirectionally coupled in such a way that the reaction heat, the polarized heat and the ohmic heat obtained by calculation of the electrochemical control equation set are used as source items to be input into the thermal model control equation; S7, meshing the geometric model; And S8, carrying out solving calculation by adopting a transient solver, judging whether a calculation result meets a preset convergence criterion, generating a set of new values for the adjustable input parameters if the judgment result does not meet the convergence criterion, returning to the step S6, and outputting a simulation result comprising a temperature field, potential distribution and lithium ion concentration distribution if the judgment result meets the convergence criterion.
2. The method for modeling the electrothermal coupling of the silicon-carbon negative electrode high specific energy lithium battery according to claim 1, wherein in the step S1, the geometric model is a two-dimensional geometric model which is one-dimensionally stacked in the thickness direction of the battery, and the battery parameters based on which the geometric model is constructed include positive electrode thickness, negative electrode thickness, separator thickness, positive electrode and negative electrode active material particle radius, porosity of a positive electrode region, separator region and a negative electrode region, arrhenius equation parameters of the relationship between the maximum lithium intercalation concentration and initial lithium intercalation concentration of the positive electrode active material and the reaction rate constant and temperature of each electrode, and the convective heat transfer coefficient of the surface of the battery.
3. The method according to claim 1, wherein the electrochemical control equation set established in the step S2 comprises: solid phase mass transfer equation describing the diffusion of lithium ions inside the active material particles: Wherein, the Respectively represents a negative electrode and a positive electrode, Represents a solid body, and the solid body is a solid, Is the lithium concentration in the positive or negative electrode active material, Is the radius of the positive electrode or negative electrode active material, Is the diffusion coefficient of lithium ions in the positive electrode or negative electrode active material, Representing time; a transport equation in the electrolyte describing the migration and diffusion of lithium ions in the electrolyte: ; Wherein, the Respectively representing a negative electrode, a separator and a positive electrode; as a fraction of the volume of the electrolyte, Is the liquid phase diffusion coefficient of lithium ions; Representing the effective diffusion coefficient of liquid-phase lithium ions in the anode, the diaphragm and the cathode; Representing a valid value; representing the concentration of lithium ions in the electrolyte; represents the distance from the leftmost side of the negative electrode; represents the specific surface area of the active material; representing the migration number of lithium ions; Representing current density; solid phase charge conservation equation for calculating solid phase potential: ; Wherein, the Respectively representing a negative electrode and a positive electrode; Is solid phase conductivity; indicating the effective conductivity of the positive or negative electrode; a solid phase current density representing the positive or negative electrode; Is a solid phase potential; a liquid phase charge conservation equation for calculating liquid phase potential: ; Wherein, the For the conductivity of the electrolyte solution, Is the electrolyte activity correlation coefficient; respectively representing a negative electrode, a separator and a positive electrode; Representing the liquid phase current density at the negative electrode, separator and positive electrode; Represents a liquid phase; Indicating the effective conductivity of the electrolyte; representing an ideal gas constant; representing temperature; representing the Faraday constant; Representing the liquid phase potential; Electrochemical reaction kinetics equations, describing the reaction rate of the electrode/electrolyte interface based on the Butler-Volmer equation: Wherein, the Is the reaction rate constant of the anode and the cathode, Is the transfer coefficient of the positive electrode and the negative electrode, Is an overpotential; Respectively representing a negative electrode and a positive electrode; Representing an equilibrium potential; Representing current density; represents the maximum lithium intercalation concentration of the positive electrode or negative electrode active material; represents the surface lithium intercalation concentration of the positive electrode or negative electrode active material; Represents the negative electrode transfer coefficient; Representing the positive transfer coefficient; Indicating either positive or negative overpotential.
4. The method for modeling electrothermal coupling simulation of a silicon-carbon negative electrode high specific energy lithium battery according to claim 3, wherein the thermal model control equation established in the step S3 is a thermal conduction equation based on energy conservation: total heat production rate of battery =Reaction heat +Polarized heat +Ohm Heat , The heat of reaction ; The polarized heat The ohmic heat Wherein, the Representing the constant pressure specific heat capacity of the material; representing the material density; representing the convective heat transfer coefficient; representing ambient temperature; representing the thermal conductivity; representing the battery temperature; Is the local current density; is the solid phase potential of the material, Is the liquid phase potential of the liquid phase, Is an equilibrium potential; Indicating the open circuit voltage.
5. The method for simulating modeling of electrothermal coupling of a silicon-carbon negative electrode high specific energy lithium battery according to claim 4, wherein the negative electrode active component of the material provided for the negative electrode region in step S4 is a silicon-carbon composite material, and the silicon-carbon composite material comprises silicon and graphite.
6. The method according to claim 5, wherein the adjustable input parameters set in step S5 include physical and chemical parameters of materials, electrical boundary conditions, thermal boundary conditions, initial temperature, initial state of charge, and calculation time steps of a transient solver.
7. The method for modeling electrothermal coupling of a silicon-carbon negative electrode high specific energy lithium battery according to claim 6, wherein in the step S6, parameters in the electrochemical control equation set are updated by an arrhenius equation, and the mathematical relationship is as follows: Wherein, the Indicating at the current temperature The reaction rate constant below; Expressed at a reference temperature The following known, reference reaction rate constants for the material itself; indicating activation energy.
8. The method for simulating modeling of electrothermal coupling of a silicon-carbon negative electrode high specific energy lithium battery according to claim 7, wherein in the step S7, when the geometric model is grid-divided, grid encryption is performed in an interface region between the electrode and the diaphragm and in a surface region of the particles.
9. The method according to claim 8, wherein in the step S8, the generating a new set of values for the adjustable input parameters includes modifying at least one of the physicochemical parameters, the electrical boundary conditions, the thermal boundary conditions, the initial temperature and initial state of charge, and the calculation time step of the transient solver of the materials set in the step S5.
10. A silicon-carbon negative electrode high specific energy lithium battery electrothermal coupling simulation modeling system, which adopts the silicon-carbon negative electrode high specific energy lithium battery electrothermal coupling simulation modeling method as claimed in any one of claims 1-9, and is characterized by comprising: the method comprises the steps that a module M1 builds a geometric model of the high-specific-energy lithium battery to be simulated based on battery parameters; The module M2 adds a physical field of the lithium ion battery in the geometric model to establish an electrochemical control equation set based on a porous electrode theory and a pseudo three-dimensional model; A module M3, adding a solid heat transfer physical field into the geometric model to establish a thermal model control equation based on the principle of energy conservation; A module M4 for setting corresponding materials for the positive electrode zone, the diaphragm zone and the negative electrode zone in the geometric model respectively; The module M5 is used for setting adjustable input parameters required by the electrochemical control equation set and the thermal model control equation; The module M6 is used for bidirectionally coupling the electrochemical control equation set and the thermal model control equation based on the value of the adjustable input parameter, wherein the coupling mode is that the reaction heat, the polarized heat and the ohmic heat obtained by calculation of the electrochemical control equation set are used as source items to be input into the thermal model control equation; Module M7, performing mesh subdivision on the geometric model; and the module M8 is used for carrying out solving calculation by adopting a transient solver and judging whether a calculation result meets a preset convergence criterion, if the judgment result does not meet the convergence criterion, generating a set of new values for the adjustable input parameters, returning to the module M6, and if the judgment result meets the convergence criterion, outputting a simulation result comprising a temperature field, potential distribution and lithium ion concentration distribution.

Description

Electrothermal coupling simulation modeling method and system for silicon-carbon negative electrode high specific energy lithium battery Technical Field The invention relates to the technical field of lithium ion battery simulation, in particular to a silicon-carbon negative electrode high specific energy lithium battery electric heating coupling simulation modeling method and system. Background With the rapid development of electric automobiles and large-scale energy storage industry, the market has put an urgent demand for the continuous increase of the energy density of lithium ion batteries. High specific energy lithium batteries employing high capacity active materials such as high nickel layered oxide anodes, silicon-based cathodes, and the like have become the current focus of research and industrialization. However, the increase in energy density is often accompanied by more complex internal physicochemical processes and increased thermal safety issues. For example, the large volume expansion of silicon anodes in the cycle, the structural instability of high nickel anodes at high temperatures, and the significant electrochemical polarization and uneven heat generation during high rate charge and discharge all pose significant challenges to the design and safety of the battery. In the process of developing and designing batteries, computer simulation technology is widely used as an important auxiliary tool. Many battery models exist, particularly state-of-the-art models for battery management systems, which focus mainly on macroscopic electrical behavior outside the battery, with model parameters typically obtained by data fitting and not going deep into the electrochemical and thermal physical mechanisms inside the battery. Such models, although simple to calculate, cannot describe the internal processes determined by the microstructure of the electrode, and it is also difficult to precisely quantify the heat generated by different sources, such as reaction heat, polarized heat, ohmic heat, and the spatial distribution thereof. Therefore, they cannot be used to guide the fine design of the internal structure of the battery, and it is also difficult to accurately predict the local overheating or performance degradation caused by the electrothermal coupling effect under the high stress working condition. The invention patent with publication number CN116680938A is found by searching patent literature, and a modeling method and a system of a lithium battery electric heating coupling model are disclosed, wherein the method comprises the steps of constructing a lithium battery open-circuit voltage dynamic model by taking the current storage electric quantity of a lithium battery as an independent variable and the open-circuit voltage of the lithium battery as a dependent variable according to actually measured open-circuit voltage data of the lithium battery; according to the actual measured internal resistance value of the lithium battery under the preset working condition, the lithium battery temperature, the charge load and the discharge multiplying power are taken as independent variables, the lithium battery discharge internal resistance value is taken as dependent variables, the lithium battery discharge internal resistance electrothermal coupling model is built, and according to the lithium battery open-circuit voltage dynamic model, the lithium battery dynamic temperature rise model and the lithium battery discharge internal resistance electrothermal coupling model, the lithium battery electrothermal coupling model is built. The patent does not extend into an electrochemical mechanism in the battery, modeling accuracy is easy to influence, and the method lacks of fine treatments such as geometric modeling, mesh division and the like, has poor simulation suitability for special batteries with high specific energy and the like, and has insufficient coupling depth and model universality. In summary, to solve the above-mentioned problems in the prior art, researching a method and a system for simulating electrothermal coupling of a silicon-carbon negative electrode high specific energy lithium battery becomes a critical task to be solved. Disclosure of Invention Aiming at the defects in the prior art, the invention aims to provide a silicon-carbon negative electrode high specific energy lithium battery electric heating coupling simulation modeling method and system. The invention provides a silicon-carbon negative electrode high specific energy lithium battery electrothermal coupling simulation modeling method, which comprises the following steps: step S1, constructing a geometric model of a high specific energy lithium battery to be simulated based on battery parameters; S2, adding a physical field of the lithium ion battery into the geometric model to establish an electrochemical control equation set based on a porous electrode theory and a pseudo three-dimensional model; S3, adding a solid heat tr