Sodium-ion battery electrochemical-thermal coupling simulation model modeling method

Abstract

The invention discloses a modeling method for an electrochemical-thermal coupling simulation model of a sodium-ion battery. The modeling method comprises the following steps: acquiring modeling parameters through a selected sodium-ion battery; establishing an electrochemical reaction model containing sodium ion adsorption reaction and an electrothermal coupling sodium ion battery model coupled with a heat transfer model by using the modeling parameters; and calibrating and calibrating the electrothermal coupling sodium ion battery model by comparing the voltage curve obtained by testing the sodium ion battery with the output voltage of the electrothermal coupling sodium ion battery model, and outputting the corrected electrothermal coupling sodium ion battery model. According to the invention, through the established sodium ion battery electrothermal coupling model which is based on electrochemical reaction and contains sodium ion adsorption reaction, real-time mutual coupling and mutual feedback of electrochemistry and heat in the sodium ion battery model are realized, some characteristic changes in the battery can be clearly reflected, and electrical properties of the battery at different adsorption rates can be compared, so that the sodium ion battery can be applied to the field of electrochemical detection. The screening of a sodium ion battery cell design scheme is facilitated, and the sodium ion battery research and development progress is accelerated.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion battery modeling, and in particular to a sodium ion battery electrochemical-thermal coupling simulation modeling method. Background Art

[0002] At present, most of the batteries used in electric vehicles are lithium-ion batteries. However, lithium-ion batteries also face problems such as lack of lithium resources, high cost, and narrow usable temperature range. Sodium-ion batteries have attracted extensive attention and research because sodium resources on the earth are far more abundant than lithium resources, sodium-ion batteries have low costs, and can operate in a wider temperature range.

[0003] With the continuous advancement of computer technology, simulation methods are increasingly being used in various aspects of the new energy field. Among them, the electrochemical model (Newman model) is widely used in new energy fields such as batteries because it takes into account the reaction principle inside the battery and has high calculation accuracy.

[0004] At present, there are a large number of patents involving lithium-ion battery simulation. For example, patent CN 110457742 A introduces a lithium-ion battery electrochemical-thermal-mechanical coupling model and modeling method; patent CN 108062430 A discloses a correction method for improving the accuracy of the Newman electrochemical model used for lithium-ion battery simulation. However, only a few patents involve sodium-ion battery simulation. For example, patent CN 117592271 A discloses a modeling method for a hybrid sodium-ion capacitor model, but it describes a sodium-ion capacitor and does not involve a sodium-ion battery. Patent CN 117117346 A describes a design and control method for a sodium-ion battery management system. The model does not use the Newman model, does not include the adsorption reaction of sodium ions, and does not reflect the internal electrochemical reaction. Therefore, it is very necessary to establish an electrochemical model that can reflect the internal mechanism of sodium-ion batteries.

[0005] As mentioned above, since there is a lack of electrochemical models of sodium ion batteries that include adsorption reactions, and the models related to sodium ion batteries in the prior art do not consider the internal reaction mechanism of the battery, it is necessary to establish an electrochemical model that can reflect the internal mechanism of sodium ion batteries. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings and defects of the prior art and to provide a modeling method for a sodium ion battery electrochemical-thermal coupling simulation model. Starting from the internal reaction principle of the sodium ion battery, mathematical language is used in simulation software (such as COMSOL) to describe the electrochemical reaction process, while considering the influence of battery heat generation on the electrochemical reaction, coupling the electrochemistry and heat, and building a complete electrochemical-thermal coupling sodium ion battery model.

[0007] A method for modeling a sodium ion battery electrochemical-thermal coupling simulation model comprises the following steps:

[0008] S1. Obtain modeling parameters by selecting a sodium-ion battery;

[0009] S2. Using the modeling parameters, an electrothermal coupled sodium ion battery model including an electrochemical reaction model of a sodium ion adsorption reaction coupled with a heat transfer model is established;

[0010] S3. Compare the voltage curve obtained by testing the sodium ion battery with the output voltage of the electrothermal coupling sodium ion battery model, calibrate and calibrate the electrothermal coupling sodium ion battery model, and output the corrected electrothermal coupling sodium ion battery model.

[0011] Among them, the modeling parameters include the testable electrochemical parameters of the sodium-ion battery as well as the material, electrode and structural parameters; the material parameters include equilibrium potential, temperature derivative, diffusion coefficient, exchange current density, which are obtained by making a half-cell for testing.

[0012] The geometric structure of the electrochemical reaction model includes positive and negative electrode current collectors, positive and negative electrode materials and separators.

[0013] Among them, the control equations of the electrochemical reaction model include the solid phase mass conservation equation, the liquid phase mass conservation equation, the solid phase charge conservation equation, the liquid phase battery cell conservation equation, the BV kinetic equation describing the electrochemical reaction at the interface between the electrode and the electrolyte, and the adsorption equation of sodium ions on the hard carbon negative electrode; wherein the adsorption process is described as an equilibrium reaction, the adsorbate has a maximum surface concentration, the adsorption rate is independent of the surface coverage of the adsorbate, and conforms to the Langmuir isotherm adsorption formula.

[0014] The solid mass conservation equation is: The boundary conditions are

[0015] The liquid phase mass conservation equation is: The boundary conditions are

[0016] The solid phase charge conservation equation is The boundary conditions are

[0017] The liquid phase charge conservation equation is: The boundary conditions are

[0018] The BV kinetic equation is

[0019] The adsorption equation is

[0020] in,

[0021] c s represents the solid phase lithium ion concentration, D s represents the solid phase diffusion coefficient, c e represents the electrolyte concentration, represents the solid phase potential, represents the liquid phase potential, Indicates the electrolyte ion transfer number, K ads is the adsorption rate constant, c A represents the surface concentration, t represents the time, r represents the distance from the center of the solid phase, R s represents the particle radius, j Li represents the lithium ion current, α s is the Faraday constant, ε e represents the liquid volume fraction, D eff represents the solid phase effective diffusion coefficient, x represents the distance from the interface between the negative electrode and the separator, L represents the thickness, σ eff represents effective electronic conductivity, I represents battery current, A represents surface area, k eff is the effective ionic conductivity, represents the effective diffusion coefficient of the liquid phase, i0 represents the exchange current density, θ represents the adsorbent surface coverage, R represents the gas constant, T represents the temperature, α c represents the cathode transfer coefficient, η represents the electrode overpotential, exp represents the exponential function, Ln represents the logarithmic function, α а represents the anode transfer coefficient.

[0022] Among them, the geometric structure of the heat transfer model is drawn according to the actual size of the soft-pack sodium-ion battery, including the core and the tabs.

[0023] Among them, the heat balance of the heat transfer model includes heat generation and heat dissipation, the heat generation includes reversible heat and irreversible heat, the reversible heat is the heat released / absorbed by sodium ions during the insertion / extraction process of the positive and negative electrodes; the irreversible heat includes ohmic heat and polarization heat.

[0024] Wherein, in the electrothermal coupling model, the heat dissipation boundary condition is set to heat dissipation on all outer walls.

[0025] The heat transfer model uses the average heat generation power of the electrochemical reaction model, and assigns the average temperature of the heat transfer model to the electrochemical reaction model, thereby achieving real-time mutual influence and feedback between the electrochemical reaction and the temperature.

[0026] The voltage curve of the sodium ion battery is obtained by performing charge and discharge tests on the battery at different rates.

[0027] The present invention establishes an electrochemical-thermal coupling model of a sodium ion battery based on the electrochemical reaction principle and including a sodium ion adsorption reaction through the method, realizes real-time mutual coupling and mutual feedback of electrochemistry and heat in the sodium ion battery model, can clearly reflect some characteristic changes inside the battery, such as electrolyte concentration, positive and negative electrode potentials, electrolyte potential, particle lithium concentration, etc., and can compare the battery electrical performance at different adsorption rates, which can help screen sodium ion battery cell design solutions, including materials, formulas, models, etc., and accelerate the research and development progress of sodium ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Flowchart of the approach to modeling a coupled electrochemical-thermal simulation model for a sodium-ion battery.

[0029] Figure 2 This is the geometric structure diagram of the one-dimensional electrochemical reaction model of the electrothermal coupling model.

[0030] Figure 3 This is the geometric structure diagram of the three-dimensional heat transfer model of the electrothermal coupling model.

[0031] Figure 4A This is the equilibrium potential diagram for sodium removal and sodium insertion at the negative electrode of the half-cell of positive and negative electrode materials.

[0032] Figure 4B This is the equilibrium potential diagram for sodium removal and sodium insertion at the positive electrode of the half-cell of positive and negative electrode materials.

[0033] Figure 5A The exchange current density diagram of the negative electrode of the half-cell of positive and negative electrode materials.

[0034] Figure 5B The exchange current density diagram of the positive electrode of the half-cell of positive and negative electrode materials.

[0035] Fig. 6A Diffusion coefficient diagram of the negative electrode of the half-cell of positive and negative electrode materials.

[0036] Figure 6B Diffusion coefficient diagram of the positive electrode of the half-cell with positive and negative electrode materials.

[0037] Fig. 7AComparison diagram of the charging simulation curve and the measured curve of the voltage structure simulated by the electrothermal coupling model (the solid line is the model simulation result, and the dotted line is the experimental test result).

[0038] Figure 7B Comparison diagram of the discharge simulation curve and the measured curve of the voltage structure simulated by the electrothermal coupling model (the solid line is the model simulation result, and the dotted line is the experimental test result).

[0039] Figure 8 The diagram shows the SOC changes during the discharge process of the positive and negative electrodes simulated by the electrothermal coupling model.

[0040] Fig. 9 The diagram of electrolyte concentration changes at different times (0s, 10s, 50s, 100s, 500s) during the discharge process simulated by the electrothermal coupling model.

[0041] Fig.10 The diagram of electrolyte potential change at different times (0s, 10s, 50s, 100s, 200s) during the discharge process simulated by the electrothermal coupling model.

[0042] Fig.11 Full-cell voltage curve for different sodium ion adsorption rates simulated by the electrothermal coupling model. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0044] A method for modeling a sodium ion battery electrochemical-thermal coupling simulation model in the present invention comprises the following steps:

[0045] S1. Obtain modeling parameters by selecting a sodium-ion battery;

[0046] S2. Using the modeling parameters, an electrothermal coupled sodium ion battery model including an electrochemical reaction model of a sodium ion adsorption reaction coupled with a heat transfer model is established;

[0047] S3. Compare the voltage curve obtained by testing the sodium ion battery with the output voltage of the electrothermal coupling sodium ion battery model, calibrate and calibrate the electrothermal coupling sodium ion battery model, and output the corrected electrothermal coupling sodium ion battery model.

[0048] In some embodiments, the modeling parameters include testable electrochemical parameters of the battery as well as material, electrode and structural parameters.

[0049] In some embodiments, the geometric structure of the electrochemical reaction model includes positive and negative electrode current collectors, positive and negative electrode materials, and a separator, which can be a one-dimensional model, a two-dimensional model, or a three-dimensional model.

[0050] In some embodiments, the control equations of the electrochemical reaction model include the solid phase mass conservation equation, the liquid phase mass conservation equation, the solid phase charge conservation equation, the liquid phase battery cell conservation equation, the BV kinetic equation describing the electrochemical reaction at the interface between the electrode and the electrolyte, and the adsorption equation of sodium ions on the hard carbon negative electrode; wherein the adsorption process is described as an equilibrium reaction, the adsorbate has a maximum surface concentration, the adsorption rate is independent of the surface coverage of the adsorbate, and conforms to the Langmuir isotherm adsorption formula.

[0051] In some embodiments, the solid phase mass conservation equation is The boundary conditions are

[0052] The liquid phase mass conservation equation is: The boundary conditions are

[0053] The solid phase charge conservation equation is The boundary conditions are

[0054] The liquid phase charge conservation equation is: The boundary conditions are

[0055] The BV kinetic equation is

[0056] The adsorption equation is

[0057] The corresponding parameters / symbols in the above equations mean:

[0058] c s Solid phase lithium ion concentration (mol / m^3)

[0059] t time (s)

[0060] D s Solid phase lithium ion diffusion coefficient (m^2 / s)

[0061] r is the distance from the center of the solid sphere (m)

[0062] R s Particle radius (m)

[0063] c e Electrolyte concentration (mol / m^3)

[0064] Solid phase potential (V)

[0065] Liquid phase potential (V)

[0066] Electrolyte ion transfer number

[0067] j Li Lithium ion current (A / m^2)

[0068] α s Electrode reaction area (m^2)

[0069] F Faraday constant

[0070] ε e Liquid volume fraction

[0071] D eff Solid phase effective diffusion coefficient (m^2 / s)

[0072] x is the distance between the negative electrode and the separator interface (m)

[0073] L Thickness(m)

[0074] σ eff Effective electronic conductivity (S / m)

[0075] I Battery current (A)

[0076] A Surface area (m^2)

[0077] κ eff Effective ion conductivity (S / m)

[0078] Liquid phase effective diffusion coefficient (m^2 / s)

[0079] i0 Exchange current density (A / m^2)

[0080] θ Adsorbent surface coverage

[0081] R Gas constant

[0082] T Temperature (K)

[0083] α c Transfer coefficient

[0084] η Electrode overpotential (V)

[0085] exp exponential function

[0086] Ln Logarithmic function

[0087] K ads represents the adsorption rate constant

[0088] cA Indicates surface concentration

[0089] α а Anode transfer coefficient

[0090] α c Cathode transfer coefficient

[0091] In some embodiments, the geometric structure of the heat transfer model is drawn according to the actual size of the soft-pack sodium-ion battery, including the core and the tabs. The heat transfer model is preferably a three-dimensional heat transfer model, but can also be a two-dimensional model.

[0092] In some embodiments, the heat balance of the heat transfer model includes heat generation and heat dissipation, the heat generation includes reversible heat and irreversible heat, the reversible heat is the heat released / absorbed by sodium ions during the insertion / extraction process of the positive and negative electrodes; the irreversible heat includes ohmic heat and polarization heat.

[0093] In some embodiments, in the electrothermal coupled sodium ion battery model, the heat dissipation boundary condition is set to heat dissipation on all outer walls.

[0094] During the battery charging and discharging process, the heat generated by the electrochemical reaction will cause the temperature inside the battery cell to change, and some parameters in the electrochemical reaction are sensitive to temperature, such as the diffusion coefficient of lithium ions in the electrode particles, the diffusion coefficient of the electrolyte, the exchange current density, the adsorption rate, etc. Therefore, it is necessary to consider the electrochemical reaction and heat in a coupled manner. Therefore, in some embodiments, the heat transfer model uses the average heat generation power of the electrochemical reaction model, and at the same time assigns the average temperature of the heat transfer model to the electrochemical reaction model, so as to realize the real-time mutual influence and feedback between the electrochemical reaction and the temperature.

[0095] In some embodiments, the voltage curve of the sodium ion battery is obtained by performing charge and discharge tests on the battery at different rates.

[0096] It should be noted that the sodium ion battery in the present application can be a soft-pack sodium ion battery, and can also be applied to other types of sodium ion batteries such as cylindrical and square ones.

[0097] It should be noted that the electrothermal coupled sodium ion battery model based on the electrochemical reaction principle of the present application, that is, the electrochemical model of the sodium ion battery with added adsorption reaction, is not limited to the one-dimensional electrochemical model coupled with the three-dimensional heat transfer model, but may also include a two-dimensional and three-dimensional fully coupled model. The electrothermal coupled sodium ion battery model is suitable for sodium ion batteries of different models and sizes, and is not limited to the battery size and material system.

[0098] Embodiment 1:

[0099] With a capacity of 3Ah NaNi 1 / 3 Fe 1 / 3 Mn1 / 3 Taking the O2 / hard carbon soft-pack sodium-ion battery as an example, the electrochemical model of the sodium-ion battery was built and the model accuracy was verified. The following steps are included:

[0100] S1. Obtain modeling parameters by selecting a soft-pack sodium-ion battery:

[0101] The parameters required for modeling are collected through testing and reference papers, mainly including parameters at three levels: material, electrode and structure. The material parameters include equilibrium potential, temperature derivative, diffusion coefficient, and exchange current density, which are obtained by making half-cells of positive and negative electrode materials for testing.

[0102] Among them, the specific test method of equilibrium potential is as follows:

[0103] The Arbin+ thermostat equipment was used to test the equilibrium potential by constant current intermittent titration, that is, the curve of electrode potential change over time was measured during the constant current process; among them, the charging GITT test: 0.01C constant current charging, each charging for 0.5h, then standing for 3-5h, recording the capacity and the potential value after standing equilibrium. The discharge GITT test: 0.01C constant current discharge, each discharge for 0.5h, then standing for 3-5h, recording the capacity and the potential value after standing equilibrium. According to the recorded values, the lithium insertion state-equilibrium potential curve was obtained.

[0104] Among them, the specific test method of temperature derivative is as follows:

[0105] At room temperature, adjust the battery to 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% SOC, let it stand for 2 hours and record the open circuit voltage OCV. Then, place the button battery at T1 temperature and let it stand for 6 hours before recording the OCV. According to the above steps, measure and record the OCV at multiple temperatures (generally covering the operating temperature of the battery) to obtain the open circuit voltage-temperature curve, whose slope is dEeq / dT (temperature derivative, a physical quantity that describes the rate of change of energy Eeq with temperature T).

[0106] The specific test method of the diffusion coefficient is performed by constant current intermittent titration (GITT). The formula used is as shown in the formula:

[0107]

[0108] where τ is the relaxation time, n m is the number of moles, V m is the molar volume of the electrode material, S is the electrode / electrolyte contact area, ΔE s is the voltage change caused by the pulse, ΔE t It is the voltage change during constant current charging and discharging.

[0109] In GITT, it is necessary to measure the coulometric titration curve. The so-called coulometric titration is to measure the potential under different sodium insertion amounts and plot the potential against the sodium insertion amount.

[0110] The exchange current density is obtained through EIS test, which will not be described in detail here.

[0111] S2. Using the modeling parameters, an electrothermal coupling model is established, which is a one-dimensional electrochemical reaction model including a sodium ion adsorption reaction coupled with a three-dimensional heat transfer model;

[0112] The electrothermal coupling model consists of a one-dimensional electrochemical reaction model and a three-dimensional heat transfer model. The main equations include the charge conservation equation, mass conservation equation, electrochemical reaction kinetics equation, and energy conservation equation. First, draw the geometric structure of the one-dimensional electrochemical reaction model, using line segments to represent it. From left to right, it includes the negative electrode current collector, negative electrode, separator, positive electrode, and positive electrode current collector, such as Figure 2 As shown in the figure, it consists of five line segments, namely the negative electrode current collector, negative electrode, separator, positive electrode, and positive electrode current collector. Different material properties are assigned to each line segment. The equilibrium potential, diffusion coefficient, temperature derivative and other parameters obtained by the previous steps are added to the material. A lithium-ion battery interface is added to the one-dimensional electrochemical reaction model. Different materials are assigned to the porous electrode. The adsorbed non-Faraday reaction is added under the negative electrode porous electrode, and the initial values ​​of the adsorbed and desorbed substances are set. The geometric structure of the three-dimensional heat transfer model is drawn according to the actual size of the soft-pack sodium-ion battery, as shown in Figure 3 As shown, add the Solid Heat Transfer interface and add the heat source and heat sink boundaries respectively.

[0113] In addition, the battery's conductivity, diffusion coefficient and other parameters change with temperature. By adding the Arrhenius formula to reflect the changes in different temperatures, the changes in the above electrochemical parameters will affect heat generation and temperature rise. Therefore, the average temperature of the three-dimensional heat transfer model is assigned to the one-dimensional electrochemical reaction model as its electrochemical reaction temperature, and the average heat generation power of the one-dimensional electrochemical reaction model is assigned to the three-dimensional heat transfer model, which can realize real-time coupling of electrochemistry and heat.

[0114] S3. Compare the voltage curve obtained by testing the soft-pack sodium-ion battery with the output voltage of the electrothermal coupling model, calibrate and calibrate the electrothermal coupling model, and output the corrected electrothermal coupling model.

[0115] The soft-pack sodium-ion battery was placed in a constant temperature oven at 25 degrees Celsius and subjected to constant current charge and discharge tests using Arbin battery testing equipment. The test rates included 0.2C, 0.5C, 1.0C, and 2.0C. The test data was processed to obtain its voltage test curve, which was compared with the voltage curve output by the electrothermal coupling model to verify the accuracy of the electrothermal coupling model.

[0116] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0117] Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is therefore intended that all changes falling within the meaning and range of equivalent elements of the claims are included in the present invention.

[0118] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A sodium ion battery electrochemical-thermal coupling simulation model modeling method, characterized in that: Includes steps: S1. Obtain modeling parameters by selecting a sodium-ion battery; S2. Using the modeling parameters, an electrothermal coupled sodium ion battery model including an electrochemical reaction model of a sodium ion adsorption reaction coupled with a heat transfer model is established; S3. Compare the voltage curve obtained by testing the sodium ion battery with the output voltage of the electrothermal coupling sodium ion battery model, calibrate and calibrate the electrothermal coupling sodium ion battery model, and output the corrected electrothermal coupling sodium ion battery model.

2. The electrochemical-thermal coupling simulation model modeling method for sodium ion batteries according to claim 1, characterized in that: The modeling parameters include the testable electrochemical parameters of the sodium-ion battery as well as the material, pole piece and structural parameters; the material parameters include equilibrium potential, temperature derivative, diffusion coefficient, exchange current density, which are obtained by making a half-cell for testing.

3. The electrochemical-thermal coupling simulation model modeling method for sodium ion batteries according to claim 1, characterized in that: The geometric structure of the electrochemical reaction model includes positive and negative electrode current collectors, positive and negative electrode materials and a separator.

4. The electrochemical-thermal coupling simulation model modeling method for sodium ion batteries according to claim 1, characterized in that: The control equations of the electrochemical reaction model include the solid phase mass conservation equation, the liquid phase mass conservation equation, the solid phase charge conservation equation, the liquid phase battery cell conservation equation, the BV kinetic equation describing the electrochemical reaction at the interface between the electrode and the electrolyte, and the adsorption equation of sodium ions on the hard carbon negative electrode; wherein the adsorption process is described as an equilibrium reaction, the adsorbate has a maximum surface concentration, the adsorption rate is independent of the surface coverage of the adsorbate, and conforms to the Langmuir isotherm adsorption formula.

5. The electrochemical-thermal coupling simulation model modeling method for sodium ion batteries according to claim 4, characterized in that: The solid mass conservation equation is: The boundary conditions are The liquid phase mass conservation equation is: The boundary conditions are The solid phase charge conservation equation is The boundary conditions are The liquid phase charge conservation equation is: The boundary conditions are The BV kinetic equation is The adsorption equation is Among them, c s represents the solid phase lithium ion concentration, D s represents the solid phase diffusion coefficient, c e represents the electrolyte concentration, represents the solid phase potential, represents the liquid phase potential, Indicates the electrolyte ion transfer number, K ads is the adsorption rate constant, c A represents the surface concentration, t represents the time, r represents the distance from the center of the solid phase, R s represents the particle radius, j Li represents the lithium ion current, α s represents the Faraday constant, ε e represents the liquid volume fraction, D eff represents the solid phase effective diffusion coefficient, x represents the distance from the interface between the negative electrode and the separator, L represents the thickness, σ eff represents effective electronic conductivity, I represents battery current, A represents surface area, κ eff is the effective ionic conductivity, represents the effective diffusion coefficient of the liquid phase, i0 represents the exchange current density, θ represents the adsorbent surface coverage, R represents the gas constant, T represents the temperature, α c represents the cathode transfer coefficient, η represents the electrode overpotential, exp represents the exponential function, Ln represents the logarithmic function, α а represents the anode transfer coefficient.

6. The electrochemical-thermal coupling simulation model modeling method for sodium ion batteries according to claim 1, characterized in that: The geometric structure of the heat transfer model is drawn based on the actual size of the soft-pack sodium-ion battery, including the core and the tabs.

7. The electrochemical-thermal coupling simulation model modeling method for sodium ion batteries according to claim 1, characterized in that: The heat balance of the heat transfer model includes heat generation and heat dissipation. The heat generation includes reversible heat and irreversible heat. The reversible heat is the heat released / absorbed by sodium ions during the insertion / extraction process of the positive and negative electrodes; the irreversible heat includes ohmic heat and polarization heat.

8. The electrochemical-thermal coupling simulation model modeling method for sodium ion batteries according to claim 1, characterized in that: In the electrothermal coupling model, the heat dissipation boundary condition is set to heat dissipation on all outer walls.

9. The electrochemical-thermal coupling simulation model modeling method for sodium ion batteries according to claim 1, characterized in that: The heat transfer model uses the average heat generation power of the electrochemical reaction model and assigns the average temperature of the heat transfer model to the electrochemical reaction model, thereby achieving real-time mutual influence and feedback between the electrochemical reaction and the temperature.

10. The electrochemical-thermal coupling simulation model modeling method for sodium ion batteries according to claim 1, characterized in that: The voltage curve of the sodium ion battery is obtained by performing charge and discharge tests on the battery at different rates.

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