Three-dimensional electrochemical-thermal coupling modeling method for analyzing space temperature gradient of cylindrical lithium ion battery

Abstract

The invention relates to a three-dimensional electrochemical-thermal coupling modeling method for cylindrical lithium ion battery space temperature gradient analysis, and belongs to the technical field of lithium ion battery modeling and simulation analysis, and the method comprises the following steps: adopting an improved pseudo two-dimensional electrochemical model, combining a three-dimensional heat conduction equation, and carrying out three-dimensional thermal coupling modeling on the three-dimensional heat conduction equation; taking into account the diffusion of lithium ions in the electrode material, reaction kinetics and the heat source resulting therefrom; the method comprises the following steps: dividing a battery space into a mandrel region, a connector region and an active material region, and introducing a heat generation distribution factor for each region; through a numerical optimization method, the heat generation distribution factor is adjusted by taking the error between the minimum simulation temperature and the temperature measured by the experiment as the target.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion battery modeling and simulation analysis, and relates to a three-dimensional electrochemical-thermal coupling modeling method for analyzing the spatial temperature gradient of a cylindrical lithium ion battery. Background Art

[0002] Lithium-ion batteries have become an indispensable energy storage solution in the fields of electric vehicles, renewable energy storage systems, portable electronic devices, etc. due to their high energy density, long cycle life and excellent chemical stability. However, their performance and safety are highly dependent on the operating temperature. Low temperature environment may induce safety hazards such as lithium dendrite growth and internal short circuit, while high temperature conditions will accelerate capacity decay, destroy the solid electrolyte interface (SEI) structure, and even cause serious problems such as thermal runaway. Existing studies have shown that lithium-ion batteries will have uneven temperature distribution during operation. The uneven temperature distribution not only significantly affects the performance of the battery, such as causing capacity decay, increased internal resistance and shortened cycle life, but may also induce serious safety hazards, such as overcharging, over-discharging, and even thermal runaway in extreme cases, causing the battery to catch fire or explode. Therefore, accurately predicting and effectively controlling the temperature distribution inside the battery has become a key technical requirement to ensure the safety of lithium-ion batteries and extend their service life.

[0003] In the existing technology, the study of thermal distribution based on numerical simulation has become an important means to reveal the non-uniform characteristics of batteries because of its advantages of high efficiency, economy and flexibility. In order to study thermal properties and improve the accuracy of simulation, electrochemical models are usually coupled with thermal models of different dimensions, so that the dynamic thermal characteristics of batteries can be described more accurately. Among them, the lumped thermal model (0D) assumes that the temperature inside the battery is uniformly distributed, the one-dimensional thermal model only considers the temperature change along the radial direction of the battery, and the two-dimensional thermal model only considers the temperature distribution along the radial and axial directions of the cylindrical battery. These thermal models are difficult to characterize the three-dimensional non-uniform thermal distribution of actual batteries due to dimensional simplification.

[0004] The actual situation shows that the electrochemical reaction and heat generation inside the battery are highly spatially non-uniform. For example, under high-rate charge and discharge or extreme operating conditions, the mandrel area, connector area, and active material area of ​​the battery exhibit significantly different heat generation behaviors due to differences in material properties, structural design, and current distribution. If this non-uniformity is not accurately characterized, it will directly lead to deviations in the model's prediction of temperature gradients in key areas, thus failing to provide a reliable basis for the optimal design of the battery thermal management system.

[0005] In recent years, in order to overcome the limitations of low-dimensional models, researchers have begun to explore three-dimensional electrochemical-thermal coupling models to more realistically simulate the temperature distribution inside the battery. However, traditional three-dimensional models have significant challenges in computational complexity and resource requirements. They simultaneously calculate radial, axial, and circumferential temperature changes. This places extremely high demands on computing power and time, limiting the scope of application of the model.

[0006] Existing electrochemical-thermal coupling models mostly assume that the heat source is evenly distributed, and do not fully consider the non-uniform heat generation characteristics caused by local electrochemical reaction rates and mass transfer differences, resulting in deviations in the prediction of temperature gradients in key areas. Therefore, a model that can accurately characterize the non-uniform heat generation characteristics is urgently needed to optimize battery thermal management strategies. Summary of the invention

[0007] In view of this, an object of the present invention is to provide a three-dimensional electrochemical-thermal coupling modeling method for analyzing the spatial temperature gradient of a cylindrical lithium-ion battery.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A three-dimensional electrochemical-thermal coupling modeling method for spatial temperature gradient analysis of cylindrical lithium-ion batteries comprises the following steps:

[0010] An improved pseudo-two-dimensional electrochemical model is used in combination with a three-dimensional heat conduction equation to consider the diffusion of lithium ions in electrode materials, reaction kinetics, and the resulting heat source.

[0011] The battery space is divided into the mandrel area, the connector area and the active material area, and a heat generation distribution factor is introduced for each area;

[0012] The heat generation distribution factor is adjusted through numerical optimization method with the goal of minimizing the error between the simulated temperature and the experimentally measured temperature.

[0013] Further, the improved pseudo two-dimensional electrochemical model includes:

[0014] A temperature-dependent correction mechanism is introduced to take into account the effect of temperature on the electrochemical behavior of the battery:

[0015]

[0016] In the formula, φ and φ ref are the physical quantities that vary with temperature and their values ​​at the reference temperature, E act,φ is the activation energy during the change process.

[0017] Furthermore, the combination of the three-dimensional heat conduction equation specifically includes:

[0018] During the charging and discharging process, the battery follows the thermal balance equation of the battery in the process. The energy conservation equation of the lithium-ion battery is expressed as:

[0019]

[0020] Among them, ρ,C p ,λ represent density, heat capacity and thermal conductivity respectively; Q cell Refers to the total heat source of the battery, including three heat sources, namely: Ohmic heat Q ohm , activation polarization heat Q pol and reaction heat Q rea ; Among them, Q rea Caused by the entropy change of the electrode material, Q pol Related to the polarization voltage during discharge, Q ohm It is caused by electrical ohmic heat in the solid phase and ionic ohmic heat in the electrolyte, and its expression is as follows:

[0021]

[0022] Q pol =Faj(Φ s -Φ e -Uj·R SEI )

[0023]

[0024] in, is the effective electronic conductivity of the electrode, is the effective ionic conductivity of the electrolyte, Φ s is the solid electrode potential, Φ e is the electrolyte potential, R is the universal gas constant, T is the temperature, F is the Faraday constant, represents the lithium ion migration number, c e is the ion concentration in the electrolyte, R SEI is the SEI film resistance, j is the local current density, and U is the open circuit voltage.

[0025] Furthermore, the division method of the mandrel area, the connector area and the active material area is as follows:

[0026] The mandrel area is the central support structure of the battery. It is made of high thermal conductivity metal and plays a key role in the uniform transfer of internal heat.

[0027] The connector area includes the tabs and end caps at both ends of the battery. It is made of high thermal conductivity metal and is the main channel for heat transfer from the battery. It is also an important interface for external heat dissipation.

[0028] The active material area includes positive and negative electrodes, electrolyte and separator. It is the core area of ​​the electrochemical reaction. The heat comes from Joule heat and reaction heat. There may be a temperature gradient inside, which needs to be modeled separately.

[0029] Furthermore, the heat generation distribution factors of the mandrel region, the connector region and the active material region are respectively:

[0030] The heat generation distribution factor is introduced to quantify the ratio between the heat generation rate of each region and the average heat generation rate of the battery. Based on the regional division method, the heat generation rate per unit volume is defined and introduced to describe the heat generation characteristics of each region. The calculation formula is as follows:

[0031]

[0032] h i =1+T SD ·S i

[0033]

[0034] Among them, h i is the heat generation coefficient of the ith region, S i is the heat generation distribution factor of the ith region, Q avg is the average heat source of the battery, Q cell is the total heat source of the battery, V cell is the total volume of the battery, T SD is the standard deviation of the temperature at n locations, T exp,i is the experimental temperature, T sim,i Simulate the temperature for the model.

[0035] Furthermore, the heat distribution factor is adjusted with the goal of minimizing the error between the simulated temperature and the experimentally measured temperature, specifically including:

[0036] Optimizing the heat generation distribution factor S by numerical optimization i , to minimize the model predicted temperature T sim,i With experimental temperature T exp,i The optimization goal is to minimize the following objective function:

[0037]

[0038] Where n is the total number of regions.

[0039] The beneficial effects of the present invention are that compared with the prior art, the present invention has significant advantages in temperature prediction accuracy and characterization of non-uniform heat generation characteristics. Through regional division and optimization of heat generation distribution factors, the model can reveal the gradient characteristics of local temperature inside the battery, especially under high-rate discharge conditions, and can accurately identify overheating in the core axis area. This capability helps to develop more accurate heat dissipation strategies to avoid performance degradation and safety hazards caused by local overheating. In addition, the temperature prediction error after model optimization is controlled within 2%, which significantly improves the reliability of the simulation results. Overall, the present invention provides a strong theoretical basis for the refined design of battery thermal management systems, which can effectively extend the battery life and improve the overall performance of the battery.

[0040] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0042] Figure 1 It is a classification diagram of electrochemical-thermal coupling model of lithium-ion batteries;

[0043] Figure 2 This is the geometric structure diagram of the three-dimensional thermal coupling model

[0044] Figure 3 For different ambient temperatures T amb The temperature comparison diagram of different discharge rate experiments and simulations is shown in Figure 1, where T amb =15℃, (b) T amb =25℃, (c) T amb =35℃;

[0045] Figure 4 The simulated temperature distribution at different ambient temperatures and discharge rates at the end of discharge; (a-1) to (a-3) are the simulated temperature distributions at ambient temperature of 15°C and discharge rates of 1C, 2C, and 3C; (b-1) to (b-3) are the simulated temperature distributions at ambient temperature of 25°C and discharge rates of 1C, 2C, and 3C; (b-1) to (b-3) are the simulated temperature distributions at ambient temperature of 35°C and discharge rates of 1C, 2C, and 3C;

[0046] Figure 5Comparison of model accuracy under DST dynamic conditions; (a) is the DST working current, (b) is the simulation and experimental results of the surface temperature under DST conditions, and (c) is the error of the surface temperature simulation results under DST conditions. DETAILED DESCRIPTION

[0047] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0048] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0049] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it is obvious to those skilled in the art that the embodiments of the present invention can be implemented without these specific details. In other embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present invention difficult to understand.

[0050] Embodiment 1:

[0051] The present invention provides a three-dimensional electrochemical-thermal coupling model based on regional division to accurately describe the non-uniform heat generation phenomenon inside a cylindrical lithium-ion battery. The model adopts an improved pseudo-two-dimensional electrochemical model, combined with a three-dimensional heat conduction equation, to comprehensively consider the diffusion of lithium ions in electrode materials, reaction kinetics, and the heat source generated thereby. In order to more accurately reflect the complex heat generation distribution inside the battery, the model divides the battery space into a core shaft area, a connector area, and an active material area, and introduces a heat generation distribution factor for each area. The distribution factor is adjusted by a numerical optimization method to minimize the error between the simulated temperature and the experimentally measured temperature, thereby improving the accuracy of temperature prediction. The numerical simulation is implemented by finite element analysis software and verified in combination with charge and discharge experiments. The results show that the model can accurately predict the battery temperature field distribution at different rates and ambient temperatures, providing strong support for the design and optimization of lithium battery thermal management systems.

[0052] Embodiment 2:

[0053] This embodiment provides a three-dimensional electrochemical-thermal coupling modeling method for analyzing the spatial temperature gradient of a cylindrical lithium-ion battery, comprising the following steps:

[0054] (1) An improved pseudo-two-dimensional electrochemical model is used in combination with a three-dimensional heat conduction equation to consider the diffusion of lithium ions in electrode materials, reaction kinetics, and the resulting heat source;

[0055] The traditional P2D model adopts the isothermal assumption and ignores the effect of temperature on the diffusion coefficient and reaction rate constant. This paper introduces a temperature-dependent correction mechanism to consider the effect of temperature on the electrochemical behavior of the battery.

[0056]

[0057] In the formula, φ and φ ref are the physical quantities that vary with temperature and their values ​​at the reference temperature, E act,φ is the activation energy during the change process.

[0058] During the charging and discharging process, the battery must follow the thermal balance equation of the battery in the process. The energy conservation equation of the lithium-ion battery can be expressed as:

[0059]

[0060] Among them, ρ,C p ,λ respectively represent density, heat capacity and thermal conductivity. In the formula, Qcell refers to the total heat source of the battery, which mainly includes three heat sources, namely, ohmic heat Q ohm , activation polarization heat Q pol and reaction heat Q rea Among them, Q rea Caused by the entropy change of the electrode material, Q pol Related to the polarization voltage during discharge, Q ohm It is caused by electrical ohmic heat in the solid phase and ionic ohmic heat in the electrolyte, and its expression is as follows:

[0061]

[0062] Q pol =Faj(Φ s -Φ e -Uj·R SEI )

[0063]

[0064] like Figure 1As shown in the figure, by considering the effect of temperature on electrochemical behavior in the electrochemical model, the traditional pseudo-two-dimensional electrochemical model is improved. Then, the thermal model of the battery characterizes the heat source of the battery through the heat balance equation and the corresponding heat source formula. Therefore, the coupling of these two models has already considered the diffusion of lithium ions in the electrode material, the reaction kinetics and the resulting heat source.

[0065] (2) Divide the battery space into the mandrel area, the connector area, and the active material area, and introduce a heat generation distribution factor for each area; Figure 2 As shown in the figure, this partitioning method fully considers the actual geometric configuration of the battery (cylindrical 18650 lithium-ion battery) and the physical properties of its internal structure, and can more intuitively describe the thermal distribution behavior of the battery. The mandrel area is divided based on the fact that it is the central support structure of the battery, usually made of high thermal conductivity metal, and plays a key role in the uniform transfer of internal heat. The connector area is divided based on the fact that it includes the pole ears and end caps at both ends of the battery, which are made of high thermal conductivity metal. It is the main channel for the heat transfer of the battery and an important interface for external heat dissipation. The active material area is divided based on the fact that it contains positive and negative electrodes, electrolytes and diaphragms, and is the core area of ​​the electrochemical reaction. The heat mainly comes from Joule heat and reaction heat. Because the material is porous and has low thermal conductivity, there may be a temperature gradient inside, so it needs to be modeled separately.

[0066] (3) The heat generation distribution factor is adjusted through numerical optimization methods with the goal of minimizing the error between the simulated temperature and the experimentally measured temperature.

[0067] By introducing the heat generation distribution factor, the ratio between the heat generation rate of each region and the average heat generation rate of the battery is quantified, thereby characterizing the internal heat generation non-uniformity. Based on the regional division method, the unit volume heat generation rate is defined and introduced to describe the heat generation characteristics of each region. The calculation formula is as follows:

[0068]

[0069] h i =1+T SD ·S i

[0070]

[0071] Among them, h i is the heat generation coefficient of the ith region, S i is the heat generation distribution factor of the ith region, Q avg is the average heat source of the battery, in W / m 3 ,Q cell is the total heat source of the battery, in W, V cell is the total volume of the battery, in m 3 , TSD is the standard deviation of the temperature at n locations, T exp,i is the experimental temperature, T sim,i is the model simulation temperature in °C.

[0072] In order to more accurately characterize the heat source distribution in different areas, the heat generation distribution factor S is optimized by numerical optimization. i , to minimize the model predicted temperature T sim,i With experimental temperature T exp,i The optimization goal is to minimize the following objective function:

[0073]

[0074] Through this optimization method, the characterization accuracy of the internal heat source distribution characteristics of the battery can be effectively improved.

[0075] Experimental example:

[0076] In order to verify the accuracy and practicality of the proposed model, this study selected Samsung 18650 cylindrical lithium-ion batteries for experimental verification. The battery has a nominal capacity of 2.5Ah, an operating voltage range of 2.5V to 4.2V, and a nominal voltage of 3.6V. A complete charge and discharge test system was built for the experiment, including the ITS5300 charge and discharge tester from Itech, the WD702 high and low temperature test chamber from Inbo Instruments, and the UT3216+ temperature tester from Uni-T. During the experiment, the battery surface temperature was monitored in real time by thermocouples, and measurement points were arranged on the battery surface to comprehensively record the temperature distribution.

[0077] like Figure 3 (a) to (c), and Figure 4 As shown in (a-1) to (c-3), the experimental conditions cover different discharge rates and ambient temperatures to fully evaluate the applicability of the model. At discharge rates of 0.5C, 1C, 2C and 3C, the ambient temperature is set to 15°C, 25°C and 35°C, respectively, and the discharge cut-off voltage is 2.5V. The experimental results show that under low-rate discharge conditions, the battery temperature rise is small and the temperature distribution is relatively uniform; while at high-rate discharge, the temperature rise in the core axis area is the most intense, especially at a rate of 3C, the core axis temperature is significantly higher than other areas. The simulation results are highly consistent with the experimental data, and the temperature prediction error is less than 2%.

[0078] In addition, in order to verify the applicability of the model under dynamic conditions, the DST condition was selected for the experiment. Figure 5As shown in (a)-(c), the results show that the model can still accurately predict the change of battery surface temperature under complex current change conditions, and the prediction error under dynamic conditions is controlled within 3%. This shows that the electrochemical-thermal coupling model of the present invention is not only suitable for steady-state conditions, but can also effectively cope with the dynamic thermal management requirements of actual usage scenarios.

[0079] In the above embodiments, the description's reference to "this embodiment" indicates that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least some embodiments, but not necessarily all embodiments. Multiple occurrences of "this embodiment" do not necessarily all refer to the same embodiment.

[0080] In the above-described embodiments, although the invention has been described in conjunction with specific embodiments of the invention, many substitutions, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art based on the foregoing description. For example, other storage structures (e.g., dynamic RAM (DRAM)) may use the embodiments discussed. Embodiments of the invention are intended to encompass all such substitutions, modifications, and variations that fall within the broad scope of the appended claims.

[0081] This embodiment further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, any one of the methods in this embodiment is implemented.

[0082] This embodiment also provides an electronic terminal, including: a processor and a memory;

[0083] The memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the terminal executes any one of the methods in this embodiment.

[0084] The computer-readable storage medium in this embodiment can be understood by ordinary technicians in this field: all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to the computer program. The aforementioned computer program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes.

[0085] The electronic terminal provided in this embodiment includes a processor, a memory, a transceiver and a communication interface. The memory and the communication interface are connected to the processor and the transceiver and complete communication with each other. The memory is used to store computer programs, the communication interface is used to communicate, and the processor and the transceiver are used to run computer programs so that the electronic terminal executes each step of the above method.

[0086] In this embodiment, the memory may include a random access memory (RAM), and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0087] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0088] The present invention can be used in many general or special computing system environments or configurations, such as personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, and the like.

[0089] The present invention may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The present invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A three-dimensional electrochemical-thermal coupling modeling method for spatial temperature gradient analysis of cylindrical lithium-ion batteries, characterized by: The following steps are involved: An improved pseudo-two-dimensional electrochemical model is used in combination with a three-dimensional heat conduction equation to consider the diffusion of lithium ions in electrode materials, reaction kinetics, and the resulting heat source. The battery space is divided into the mandrel area, the connector area and the active material area, and a heat generation distribution factor is introduced for each area; The heat generation distribution factor is adjusted through numerical optimization method with the goal of minimizing the error between the simulated temperature and the experimentally measured temperature.

2. The three-dimensional electrochemical-thermal coupling modeling method for spatial temperature gradient analysis of cylindrical lithium-ion batteries according to claim 1, characterized in that: The improved pseudo two-dimensional electrochemical model includes: A temperature-dependent correction mechanism is introduced to take into account the effect of temperature on the electrochemical behavior of the battery: In the formula, φ and φ ref are the physical quantities that vary with temperature and their values ​​at the reference temperature, E act,φ is the activation energy during the change process.

3. The three-dimensional electrochemical-thermal coupling modeling method for spatial temperature gradient analysis of cylindrical lithium-ion batteries according to claim 1, characterized in that: The combination of the three-dimensional heat conduction equation specifically includes: During the charging and discharging process, the battery follows the thermal balance equation of the battery in the process. The energy conservation equation of the lithium-ion battery is expressed as: Among them, ρ,C p ,λ represent density, heat capacity and thermal conductivity respectively; Q cell Refers to the total heat source of the battery, including three heat sources, namely: Ohmic heat Q ohm , activation polarization heat Q pol and reaction heat Q rea ; Among them, Q rea Caused by the entropy change of the electrode material, Q pol Related to the polarization voltage during discharge, Q ohm Caused by electrical ohmic heating in the solid phase and ionic ohmic heating in the electrolyte.

4. The three-dimensional electrochemical-thermal coupling modeling method for spatial temperature gradient analysis of cylindrical lithium-ion batteries according to claim 3, characterized in that: Q ohm The expression is as follows: Q pol =Faj(Φ s -Φ e -U-j·R SEI ) in, is the effective electronic conductivity of the electrode, is the effective ionic conductivity of the electrolyte, Φ s is the solid electrode potential, Φ e is the electrolyte potential, R is the universal gas constant, T is the temperature, F is the Faraday constant, represents the lithium ion migration number, c e is the ion concentration in the electrolyte, R SEI is the SEI film resistance, j is the local current density, and U is the open circuit voltage.

5. The three-dimensional electrochemical-thermal coupling modeling method for spatial temperature gradient analysis of cylindrical lithium-ion batteries according to claim 1, characterized in that: The division method of the mandrel area, the connector area and the active material area is as follows: The mandrel area is the central support structure of the battery. It is made of high thermal conductivity metal and plays a key role in the uniform transfer of internal heat. The connector area includes the tabs and end caps at both ends of the battery. It is made of high thermal conductivity metal and is the main channel for heat transfer from the battery. It is also an important interface for external heat dissipation. The active material area includes positive and negative electrodes, electrolyte and separator. It is the core area of ​​the electrochemical reaction. The heat comes from Joule heat and reaction heat. There may be a temperature gradient inside, which needs to be modeled separately.

6. The three-dimensional electrochemical-thermal coupling modeling method for spatial temperature gradient analysis of cylindrical lithium-ion batteries according to claim 1, characterized in that: The heat generation distribution factors of the mandrel region, the connector region and the active material region are respectively: The heat generation distribution factor is introduced to quantify the ratio between the heat generation rate of each region and the average heat generation rate of the battery. Based on the regional division method, the heat generation rate per unit volume is defined and introduced to describe the heat generation characteristics of each region. The calculation formula is as follows: Among them, h i is the heat generation coefficient of the ith region, S i is the heat generation distribution factor of the ith region, Q avg is the average heat source of the battery, Q cell is the total heat source of the battery, V cell is the total volume of the battery, T SD is the standard deviation of the temperature at n locations, T exp,i is the experimental temperature, T sim,i Simulate the temperature for the model.

7. The three-dimensional electrochemical-thermal coupling modeling method for spatial temperature gradient analysis of cylindrical lithium-ion batteries according to claim 1, characterized in that: The heat generation distribution factor is adjusted with the goal of minimizing the error between the simulated temperature and the experimentally measured temperature, specifically including: Optimizing the heat generation distribution factor S by numerical optimization i , to minimize the model predicted temperature T sim,i With experimental temperature T exp,i The optimization goal is to minimize the following objective function: Where n is the total number of regions.

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