A method for constructing a multi-physical field coupling lithium-sulfur battery simulation analysis model

Abstract

This invention relates to a method for constructing a multiphysics-coupled simulation analysis model for lithium-sulfur batteries. An electrochemical model of the lithium-sulfur battery is constructed based on its electrochemical characteristics, and a transient heat generation model is constructed based on its thermal characteristics. An accelerating calorimeter (ARC) is used to perform adiabatic testing on the lithium-sulfur battery samples, and a charge-discharge apparatus (HPPC) is used to perform mixed power pulse characteristic testing on the samples. The multiphysics-coupled simulation analysis model is validated based on the test data. This model can simulate the electrochemical and thermal behavior of lithium-sulfur batteries under different operating conditions, providing optimization for the cell structure design, battery pack structure design, and assembly design of lithium-sulfur batteries, and has broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of lithium-sulfur battery technology, and in particular to a method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model. Background Technology

[0002] Compared to lithium-ion batteries, lithium-sulfur batteries have the advantage of higher specific energy, being 2-3 times that of currently commercialized lithium-ion batteries. Furthermore, lithium-sulfur batteries boast abundant reserves of key materials, low cost, and environmental friendliness. Therefore, lithium-sulfur batteries have broad application prospects in long-endurance drones, electric vehicles, energy storage power stations, portable electronic devices, and aerospace and defense fields. Lithium-sulfur batteries generate heat during charging and discharging, causing a temperature rise. However, the limited thermal conductivity of lithium-sulfur batteries can lead to uneven temperature distribution within the battery. Therefore, the structural and operational design of large-capacity lithium-sulfur batteries or battery packs must comprehensively consider the battery's thermal and electrochemical behavior.

[0003] There are two main sources of heat generation in lithium-sulfur battery packs: First, the Joule effect generates heat as current flows through resistive components such as the electrodes, electrolyte, and separator during battery operation. Second, the self-discharge phenomenon occurs due to the decomposition of electrode materials, generating more heat than Joule heating and potentially occurring even when the battery is not in operation. Self-discharge is most likely to occur at the beginning of discharge and during the resting period after charging.

[0004] Currently, the design of lithium-sulfur batteries mainly relies on adjusting design parameters based on practical experience and optimizing them through orthogonal experiments. This approach suffers from drawbacks such as high cost, cumbersome process, and inflexibility. Simulation methods for battery packs, limited by experimental conditions, can mostly only collect temperature changes at local or multiple locations, failing to fully reflect the overall internal heat distribution of the battery.

[0005] Using simulation models for calculations can reduce experimental costs, avoid the complexity of multiple experiments, and prevent safety issues. Accurately validated models can effectively reflect the battery's operating state, electrochemical reactions, thermal reactions, and potential changes, and can predict the performance of battery modules or battery packs with scaled-up battery capacity or multiple battery cells assembled from the same process.

[0006] Therefore, it is essential to develop a method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model for the simulation design of lithium-sulfur batteries or battery packs. Summary of the Invention

[0007] The purpose of this invention is to provide a multi-physics coupled lithium-sulfur battery simulation analysis model and a model-based simulation method for lithium-sulfur batteries or battery packs. This method, through the scientific and reasonable construction and correction of the simulation model, can be used to predict the performance of lithium-sulfur batteries and battery packs with equivalent scale-up of the same system and process.

[0008] The technical solution adopted by this invention to achieve the above objectives is: a method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model, comprising the following steps:

[0009] Step 1: Construct a three-dimensional model of the lithium-sulfur battery, including its geometric dimensions, thermophysical parameters, and electrochemical parameters;

[0010] Step 2: Based on the electrochemical principle of lithium-sulfur batteries, construct the electrochemical equations for lithium-sulfur batteries, and construct an electrochemical model of lithium-sulfur batteries according to the electrochemical equations to output the electrical characteristics of the batteries; and configure the electrical characteristics in the three-dimensional battery model for visualization.

[0011] Step 3: Based on the battery heat generation principle and the set lithium-sulfur battery usage scenario, determine the transient heat generation power of the lithium-sulfur battery, construct a heat generation model of the lithium-sulfur battery based on the battery heat generation power, and output the thermal characteristics of the battery; and configure the thermal characteristics in the battery 3D model for visualization.

[0012] Step 4: Couple the electrochemical model and the thermal model to obtain the multi-physics coupled lithium-sulfur battery model of electrochemistry and thermal.

[0013] Step 5: Simulate the multi-physics coupled lithium-sulfur battery model to obtain simulation result data; compare the test result standard data of the lithium-sulfur battery reference sample corresponding to the battery model with the simulation result data to obtain the verification accuracy of the multi-physics coupled lithium-sulfur battery model.

[0014] Step 6: When the verification accuracy reaches the set standard, adjust the geometric dimensions of the lithium-sulfur battery under test according to the prediction requirements, or construct a battery pack model based on the battery model, so as to perform performance prediction after the battery or battery pack specifications are scaled up with the same process.

[0015] The battery geometry includes one or more of the following: battery electrode length, battery electrode width, battery current collector length, battery current collector width, battery current collector thickness, battery tab position, battery tab arrangement, battery length, battery width, and battery thickness.

[0016] The thermophysical parameters include one or more of the following: mass, density, specific heat capacity, thermal conductivity, and thermal runaway temperature of the lithium-sulfur battery and each material in the lithium-sulfur battery.

[0017] The electrochemical parameters include one or more of voltage, internal resistance, capacity, energy, and power.

[0018] In step 3, the heat generation model is obtained in the following way:

[0019] The heat generation power of lithium-sulfur batteries was determined experimentally.

[0020] The battery was placed in a constant temperature environment, and the heat generated by the battery in this environment, h2, was tested using a calorimeter.

[0021] In the initial stage, the heating power h0 of the battery is equal to the cooling power h1;

[0022] During battery operation, the battery temperature and heating power are controlled to ensure that the battery's own heat generation power is always h2+h0=h1;

[0023] The heat output power of the battery is obtained as h2 = h1 - h0.

[0024] In step 3, the heat generation model is obtained in the following way:

[0025] The temperature change curve f(t) of a lithium-sulfur battery under adiabatic conditions was experimentally measured. The heat generation was fitted as a function with time as the independent variable, and the heat generation power of the battery is the first derivative of this function.

[0026] T = f(t)

[0027]

[0028] Q' = q = c p mT'=c p mf'(t)

[0029] Where T is temperature, Q is the heat generated by the battery, and C is the temperature. p ΔT is the specific heat capacity, m is the mass, ΔT is the temperature increment, T0 is the initial temperature, q is the battery heat generation power, and t is the time.

[0030] In step 3, the heat generation model is obtained in the following way:

[0031] By conducting hybrid pulse tests, the internal resistance of the battery at different rates and under different SOC states was measured. The internal resistance was fitted as a polynomial function with SOC as the independent variable, and the main heat generation power of the lithium-sulfur battery under constant current discharge was obtained. The heat generation power of the battery tab was calculated by measuring the internal resistance of the tab. The sum of the main heat generation power and the heat generation power of the tab was taken as the total heat generation power of the battery.

[0032] Step 4 is as follows:

[0033] The electrochemical model constructed in step 3 and the thermal model constructed in step 4 are calculated simultaneously to output the electrical and thermal characteristics of the battery, which together constitute an electrochemical-thermal multiphysics coupled lithium-sulfur battery model.

[0034] A method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model further includes step 7, applying the multi-physics coupled lithium-sulfur battery model to conduct at least one of the following: structural development of a single lithium-sulfur battery cell, structural design of a lithium-sulfur battery pack, and thermal management design of a lithium-sulfur battery pack.

[0035] The present invention has the following beneficial effects and advantages:

[0036] This invention proposes a multi-physics coupled lithium-sulfur battery simulation analysis model. Addressing the problem that existing lithium-ion battery simulation models cannot reflect the temperature changes caused by heat generated from self-discharge reactions during operation and resting, this invention uses a temperature-based battery heat generation equation to macroscopically describe the overall temperature change behavior of a single lithium-sulfur battery cell during operation, describing the total heat generation of all electrochemical thermal behaviors, including the self-discharge reaction. To address the issue that existing thermoelectric coupling methods do not consider the unevenness of electrochemical and thermal reactions, this solution uses linear projection or linear stretching to couple and transfer physical quantities, achieving coupling and parameter transfer between different geometric models and different physical fields. This multi-physics coupled lithium-sulfur battery simulation analysis model, through scientific and reasonable model construction and modification, can be used for performance prediction of battery modules or battery packs with scaled-up battery capacity or multiple battery cells assembled from the same process. Attached Figure Description

[0037] Figure 1 Flowchart of the multi-physics coupled lithium-sulfur battery simulation analysis model provided in this embodiment of the invention;

[0038] Figure 2a The output voltage curve and temperature change curve of the lithium-sulfur battery reference sample obtained under 0.1C discharge at 25℃ adiabatic conditions are shown in the embodiments of the present invention.

[0039] Figure 2b The output voltage curve and temperature change curve of the lithium-sulfur battery reference sample obtained under 0.2C discharge at 25℃ adiabatic conditions are shown in the embodiments of the present invention.

[0040] Figure 3a The output voltage curve and temperature change curve of the lithium-sulfur battery reference sample obtained under 0.1C charging under adiabatic conditions at 25°C are provided for embodiments of the present invention.

[0041] Figure 3b The output voltage curve and temperature change curve of the lithium-sulfur battery reference sample obtained under 0.2C charging at 25°C are provided for embodiments of the present invention.

[0042] Figure 4 Temperature change curves and battery simulation model output curves of lithium-sulfur battery reference samples obtained under 0.2C discharge at 25℃ adiabatic conditions provided in this embodiment of the invention;

[0043] Figure 5a The graph shows the change in heat generation power of a lithium-sulfur battery reference sample under a discharge condition of 0.1C at 25°C, as measured by a calorimeter provided in this embodiment of the invention.

[0044] Figure 5b The graph shows the change in heat generation power of a lithium-sulfur battery reference sample under a 25°C, 0.2C charging condition, as measured by a calorimeter provided in this embodiment of the invention.

[0045] Figure 6 The graph shows the internal resistance variation of a lithium-sulfur battery reference sample under different ambient temperatures during 0.2C discharge, obtained from a hybrid power pulse test provided in this embodiment of the invention. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any way, that is, not intended to limit the scope of protection of the present invention.

[0047] This invention discloses a method for constructing a multiphysics-coupled simulation analysis model for lithium-sulfur batteries. Lithium-sulfur batteries are a novel type of lithium-ion secondary battery, characterized by low cost, environmental friendliness, and high specific energy. Unlike lithium-ion batteries, lithium-sulfur batteries exhibit two voltage plateaus in their discharge curves, with different thermal characteristics at each plateau. An electrochemical model for lithium-sulfur batteries is constructed based on their electrochemical characteristics, and a transient heat generation model is constructed based on their thermal characteristics. Accelerated calorimetry (ARC) is used to perform adiabatic testing on lithium-sulfur battery samples, and a charge-discharge apparatus (HPPC) is used to perform mixed power pulse characteristic testing on the samples. The multiphysics-coupled simulation analysis model for lithium-sulfur batteries is validated based on the test data. This model can simulate the electrochemical and thermal behavior of lithium-sulfur batteries under different operating conditions, providing optimization for the cell structure design, battery pack structure design, and assembly design of lithium-sulfur batteries, and has broad application prospects.

[0048] The multiphysics-coupled lithium-sulfur battery simulation analysis model of this invention is mainly used for performance prediction of lithium-sulfur batteries and battery packs with equivalent scale-up based on the same system and process. This simulation method first constructs a multiphysics-coupled lithium-sulfur battery simulation analysis model, then verifies the accuracy of the model's predictions. When the accuracy verification meets the standard, the model and the prediction requirements of the lithium-sulfur battery and battery pack to be predicted can be used to predict the performance of the equivalent scale-up battery.

[0049] Because the description of the implementation process of this invention involves many physical parameters, to facilitate understanding of the technical solution of this invention, the physical parameters that may be used later are first presented in a list format. When each physical parameter appears again later, it will not be described individually, as shown in Table 1.

[0050] Table 1

[0051]

[0052] like Figure 1 As shown, the main method steps for implementing this invention include:

[0053] Step 1: Use 3D modeling software to construct a battery model of the lithium-sulfur battery and determine the battery's geometric dimensions, thermal properties, and electrochemical parameters;

[0054] Specifically, the battery model of a lithium-sulfur battery can be established based on the needs of lithium-sulfur battery simulation or based on actual lithium-sulfur battery samples, which we call lithium-sulfur battery reference samples.

[0055] Battery geometry includes one or more of the following: battery electrode length, battery electrode width, battery current collector length, battery current collector width, battery current collector thickness, battery tab position, battery tab arrangement, battery length, battery width, and battery thickness. Thermal properties include one or more of the following: mass, density, specific heat capacity, thermal conductivity, and thermal runaway temperature of the lithium-sulfur battery and its constituent materials. Electrochemical parameters may include one or more of the following: voltage, internal resistance, capacity, energy, and power.

[0056] The methods for obtaining the above parameters are not strictly limited here, and conventional methods in this field can be used to obtain the above battery geometry, thermophysical parameters and electrochemical parameters.

[0057] Step 2: Based on the electrochemical principle of lithium-sulfur batteries, construct the electrochemical equations of lithium-sulfur batteries, and construct the electrochemical model of lithium-sulfur batteries based on the electrochemical equations.

[0058] Specifically, in this embodiment of the invention, numerical analysis software is used to model and calculate the lithium-sulfur battery. A relatively simple semi-empirical electrochemical model is selected. This model is suitable for simulating relatively simple battery operating conditions; it only requires providing the model with experimentally measured data of voltage changes over time under constant current, and specifying the battery's discharge rate under this model to simulate the operation of the lithium-sulfur battery pack under experimental conditions. In the semi-empirical electrochemical model, the relationship between current transport rate per unit volume and electrochemical reaction heat and potential is as follows:

[0059]

[0060] The depth of discharge (DOD) is related to the remaining battery capacity (SOC), and DOD = 1 - SOC. The fitting functions Y and U are derived from the provided experimental data:

[0061] U = a0 + a1(DOD) + a2(DOD) 2 +a3(DOD) 3 +a4(DOD) 4 +a5(DOD) 5

[0062] Y = b0 + b1(DOD) + b2(DOD) 2 +b3(DOD) 3 +b4(DOD) 4 +b5(DOD) 5

[0063] Where a0~a5 and b0~b5 are constants that best match the battery modeling results with experimental data at an ambient temperature of 25℃.

[0064] Due to the multi-domain and multi-physics characteristics of lithium-sulfur batteries, modeling them is very difficult. The computational domains related to different physical properties require different length scales, complicating the problem. In battery thermal analysis, the goal is to determine the temperature distribution over the length of a single cell; in electrochemical analysis, the physical process of lithium-sulfur migration occurs in the anode-separation-cathode interlayer (electrode pair length); and the migration of lithium-sulfur in the active material occurs at the atomic scale. Therefore, a multi-physics coupled transient heat dissipation model of the battery pack is needed to simultaneously solve and calculate multiple mathematical equations. In computational fluid dynamics (CFD), the following differential equation is used to solve the electric field at the battery scale:

[0065]

[0066] Calculated under this model An electrochemical reaction sub-model that can be applied to the transient heat dissipation model of a battery pack with multi-physics coupling.

[0067] Step 3: Based on the battery heat generation principle and the set lithium-sulfur battery usage scenario, determine the transient heat generation power of the lithium-sulfur battery, and construct a heat generation model of the lithium-sulfur battery based on the battery heat generation power.

[0068] Specifically, there may be more than one method for determining the heat production capacity, and it may include one or a combination of the following methods:

[0069] a) The heat generation power of a lithium-sulfur battery is determined experimentally. The battery is placed in a constant-temperature environment, and a calorimeter is used to measure the heat generation h2 of the battery under this environment. The test system includes a cooling system and a heating system. Initially, the heating power h0 of the battery is equal to the cooling power h1. During the battery's operation, the battery temperature and the system's heating power are controlled to ensure that the battery's heat generation power h2 + h0 = h1. Then, the device can output the battery's heat generation power, i.e., h2 = h1 - h0. Figure 5a , Figure 5b As shown.

[0070] b) The temperature change of lithium-sulfur batteries under adiabatic conditions was experimentally measured. Accelerated calorimetry (ARC) was used to test the batteries, allowing for the measurement of the charge-discharge temperature rise of individual cells under adiabatic conditions. ARC is a method for testing and analyzing battery thermal safety under near-adiabatic conditions. It can simulate the thermal characteristics of exothermic reaction processes when internal heat cannot dissipate in time, obtaining the kinetic parameters of the reaction under thermal runaway conditions. As a safety testing instrument for lithium-sulfur batteries, the adiabatic accelerated calorimeter provides a precisely controlled adiabatic environment, making the reaction closer to the real reaction process. Based on the test results, the battery's specific heat capacity, thermal conductivity, and other test results can be obtained, providing necessary design parameters and references for the design of battery pack thermal balance. Based on the temperature change over time curve under adiabatic conditions, such as... Figure 2a , Figure 2b , Figure 3a , Figure 3b As shown. The heat generation is fitted as a function with time as the independent variable, and the heat generation power of the battery is the first derivative of this function:

[0071] T = f(t)

[0072]

[0073] Q' = q = c p mT'=c p mf'(t)

[0074] c) The internal resistance of the battery at different rates and under different states of charge (SOC) was measured by the hybrid power pulse test (HPPC).

[0075] The internal resistance is fitted as a polynomial function with SOC as the independent variable, such as... Figure 6 The figure shows the internal resistance as a function of SOC at different temperatures. Further, the heat generation power under constant current discharge conditions can be obtained. This step yields the main heat generation power of the lithium-sulfur battery, while the heat generation power of the battery tabs can be calculated by measuring the tab internal resistance. Under constant current operating conditions, the heat generation power of the tabs is approximately constant. Therefore, the total heat generation power of the battery is the sum of the main heat generation power and the tab heat generation power.

[0076] Unlike other lithium-ion and lithium metal batteries, lithium-sulfur batteries exhibit self-heating / self-endothermic reactions during operation. Therefore, different modeling methods have their advantages for different operating conditions. In a normal temperature and pressure environment, method a) can construct a relatively accurate heat generation model of the battery under charge and discharge conditions, such as... Figure 4 As shown; in environments such as near space and stratosphere, method b) can obtain highly accurate simulation results in near-adiabatic application environments; method c) constructs a heat generation model by the battery internal resistance, which can take into account the heat generation of the battery tabs.

[0077] Step 4: Couple the electrochemical model and the thermal model to obtain an electrochemical-thermal multiphysics coupled lithium-sulfur battery model;

[0078] Specifically, step 3 constructs an electrochemical model of the lithium-sulfur battery, and step 4 constructs a thermal model. During transient calculations, both models are used simultaneously, operating independently without affecting each other. The electrochemical model outputs the battery's electrical characteristics, such as voltage distribution, current distribution, and depth of discharge, while the thermal model outputs its thermal characteristics, such as temperature changes, temperature distribution, and thermal power changes. The different outputs together constitute an electrochemical-thermal multiphysics coupled lithium-sulfur battery model.

[0079] Step 5: Simulate the multiphysics coupling model to obtain simulation result data. Compare the test result standard data of the lithium-sulfur battery reference sample corresponding to the battery model with the simulation result data to obtain the verification accuracy of the model.

[0080] Specifically, after obtaining the multi-physics coupled lithium-sulfur battery simulation analysis model, simulation results are obtained by performing the simulation, and then the model's effectiveness is verified by comparing it with the standard test results of lithium-sulfur battery reference samples.

[0081] The method for obtaining the standard data of the test results of the lithium-sulfur battery reference sample in this step can be achieved by performing constant current discharge at multiple set rates on the lithium-sulfur battery reference sample at multiple set temperatures; wherein the cutoff condition for constant current discharge is voltage; during the charging and discharging process, the surface temperature and internal temperature of the lithium-sulfur battery reference sample are collected by external or internal thermocouples, thermistors or infrared imagers; finally, the voltage-time curve and temperature distribution-time function relationship of the lithium-sulfur battery reference sample are obtained.

[0082] The voltage-time curves and temperature distribution-time function relationships of the lithium-sulfur battery reference samples obtained through experiments are compared with simulation data. If the accuracy requirements are met, an effective lithium-sulfur battery performance prediction model—a multiphysics coupled lithium-sulfur battery simulation analysis model—is obtained. This model can be used to predict the performance of lithium-sulfur batteries, including battery temperature, depth of discharge, and heat generation power. A goodness-of-fit index is used to describe the degree of fit between the simulation data and experimental data, verifying the model's reliability. A better fit index (closer to 1) indicates a better simulation effect; generally, a value greater than 0.9 is considered sufficient to reflect the actual situation, and the model is usable.

[0083] Step 6: When the verification accuracy reaches the standard, determine the prediction requirements based on the actual situation of the lithium-sulfur battery or battery pack to be predicted, adjust the battery geometry or construct a battery pack model according to the prediction requirements, and perform performance prediction after scaling up the specifications of the battery or battery pack with the same process.

[0084] Furthermore, when the verification accuracy does not meet the standard, the simulation analysis model of the multiphysics coupled lithium-sulfur battery can be adjusted based on the difference between the standard test data and the simulation results. The adjusted multiphysics coupled lithium-sulfur battery simulation analysis model can then be simulated and verified again. Alternatively, the model can be rebuilt.

[0085] Step 7: Apply the multi-physics coupled lithium-sulfur battery simulation analysis model to the product development and engineering design of lithium-sulfur batteries.

[0086] Specifically, the multiphysics coupled lithium-sulfur battery simulation analysis model can be applied to the following aspects according to usage requirements:

[0087] a) Structural development of lithium-sulfur battery cells. Multiphysics-coupled lithium-sulfur battery simulation models can output the current and voltage distributions within a single cell, calculate the depth of discharge under transient conditions, and evaluate the uniformity of current, voltage, and depth of discharge at the cell level. This allows for the acquisition of more reasonable dimensional parameters for lithium-sulfur battery cells, such as length, width, and thickness. Reasonable dimensional parameters enable better performance of the lithium-sulfur battery's charge and discharge cycles, thereby increasing battery capacity.

[0088] b) Structural Design of Lithium-Sulfur Battery Packs. Multiphysics-coupled simulation models of lithium-sulfur batteries can output the transient temperature changes of individual battery cells. By amplifying the heat generation power of each cell to the heat generation power of the entire battery pack, the transient temperature changes and temperature distribution of the lithium-sulfur battery pack can be further derived. Based on the temperature distribution of the battery pack, the length, width, and height dimensions of the battery pack are adjusted, as is the arrangement of the cells within the pack, to achieve a more uniform temperature distribution. Since the electrical characteristics of lithium-sulfur batteries are highly sensitive to temperature, their performance varies significantly under different temperatures. A more uniform internal temperature of the battery pack is beneficial for improving the consistency of the electrical performance of the cells within the lithium-sulfur battery pack.

[0089] c) Thermal management design of lithium-sulfur battery packs. Under different application environments, the internal temperature of lithium-sulfur battery packs requires external control. This can be achieved by heating or insulation to increase the internal temperature, or by heat dissipation or cooling to decrease it. Multiphysics-coupled lithium-sulfur battery simulation models can reveal the transient temperature changes and temperature distribution of the battery pack, thereby determining whether heating or cooling designs are necessary to maintain the battery pack temperature at a suitable operating temperature.

[0090] This invention proposes a multi-physics coupled lithium-sulfur battery simulation analysis model. Addressing the problem that existing lithium-sulfur battery simulation analysis models cannot reflect the temperature changes caused by heat generated from self-discharge reactions during operation and resting, this invention uses a temperature-based battery heat generation equation to macroscopically describe the overall temperature change behavior of a single lithium-sulfur battery cell during operation, describing the total heat generation of all electrochemical thermal behaviors, including the self-discharge reaction. To address the issue that existing thermoelectric coupling methods do not consider the unevenness of battery electrochemical and thermal reactions, this solution uses linear projection or linear stretching to couple and transfer physical quantities, achieving coupling and parameter transfer between different geometric models and different physical fields. The multi-physics coupled lithium-sulfur battery simulation analysis model proposed in this invention, through scientific and reasonable model construction and modification, can be used for performance prediction of battery modules or battery packs with scaled-up battery capacity or multiple battery cells assembled from the same process.

[0091] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for constructing a simulation analysis model for a lithium-sulfur battery with multi-physics coupling, characterized in that, Includes the following steps: Step 1: Construct a three-dimensional model of the lithium-sulfur battery, including its geometric dimensions, thermophysical parameters, and electrochemical parameters; Step 2: Based on the electrochemical principle of lithium-sulfur batteries, construct the electrochemical equation of lithium-sulfur batteries, and construct the electrochemical model of lithium-sulfur batteries according to the electrochemical equation to output the electrical characteristics of the batteries. The electrical characteristics are then configured in the three-dimensional model of the battery for visualization. Step 3: Based on the battery heat generation principle and the set lithium-sulfur battery usage scenario, determine the transient heat generation power of the lithium-sulfur battery, and construct a heat generation model of the lithium-sulfur battery based on the battery heat generation power to output the thermal characteristics of the battery. The thermal properties are then configured in the three-dimensional model of the battery for visualization. Step 4: Couple the electrochemical model and the thermal model to obtain the multi-physics coupled lithium-sulfur battery model of electrochemistry and thermal. Step 5: Simulate the multi-physics coupled lithium-sulfur battery model to obtain simulation result data; compare the test result standard data of the lithium-sulfur battery reference sample corresponding to the battery model with the simulation result data to obtain the verification accuracy of the multi-physics coupled lithium-sulfur battery model. Step 6: When the verification accuracy reaches the set standard, adjust the geometric dimensions of the lithium-sulfur battery under test according to the prediction requirements, or construct a battery pack model based on the battery model, so as to perform performance prediction after the battery or battery pack specifications are scaled up with the same process.

2. The method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model according to claim 1, characterized in that, The battery geometry includes one or more of the following: battery electrode length, battery electrode width, battery current collector length, battery current collector width, battery current collector thickness, battery tab position, battery tab arrangement, battery length, battery width, and battery thickness.

3. The method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model according to claim 1, characterized in that, The thermophysical parameters include one or more of the following: mass, density, specific heat capacity, thermal conductivity, and thermal runaway temperature of the lithium-sulfur battery and each material in the lithium-sulfur battery.

4. The method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model according to claim 1, characterized in that, The electrochemical parameters include one or more of voltage, internal resistance, capacity, energy, and power.

5. The method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model according to claim 1, characterized in that, In step 3, the heat generation model is obtained in the following way: The heat generation power of lithium-sulfur batteries was determined experimentally. The battery was placed in a constant temperature environment, and the heat generated by the battery in this environment, h2, was tested using a calorimeter. In the initial stage, the heating power h0 of the battery is equal to the cooling power h1; During battery operation, the battery temperature and heating power are controlled to ensure that the battery's own heat generation power is always h2+h0=h1; The heat output power of the battery is obtained as h2 = h1 - h0.

6. The method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model according to claim 1, characterized in that, In step 3, the heat generation model is obtained in the following way: The temperature change curve f(t) of a lithium-sulfur battery under adiabatic conditions was experimentally measured. The heat generation was fitted as a function with time as the independent variable, and the heat generation power of the battery is the first derivative of this function. T = f(t) Q'=q=c p mT'=c p mf'(t) Where T is temperature, Q is heat generated by the battery, and C is... p ΔT is the specific heat capacity, m is the mass, ΔT is the temperature increment, T0 is the initial temperature, q is the battery heat generation power, and t is the time.

7. The method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model according to claim 1, characterized in that, In step 3, the heat generation model is obtained in the following way: By conducting hybrid pulse tests, the internal resistance of the battery at different rates and under different SOC states was measured. The internal resistance was fitted as a polynomial function with SOC as the independent variable, and the main heat generation power of the lithium-sulfur battery under constant current discharge was obtained. The heat generation power of the battery tab was calculated by measuring the internal resistance of the tab. The sum of the main heat generation power and the heat generation power of the tab was taken as the total heat generation power of the battery.

8. The method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model according to claim 1, characterized in that, Step 4 is as follows: The electrochemical model constructed in step 3 and the thermal model constructed in step 4 are calculated simultaneously to output the electrical and thermal characteristics of the battery, which together constitute an electrochemical-thermal multiphysics coupled lithium-sulfur battery model.

9. The method for constructing a multi-physics coupled lithium-sulfur battery simulation analysis model according to claim 1, characterized in that, It also includes step 7, which involves applying a multi-physics coupled lithium-sulfur battery model to conduct structural research and development of a single sulfur battery cell, structural design of a lithium-sulfur battery pack, and thermal management design of a lithium-sulfur battery pack.

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