A battery thermal runaway analysis method and device based on electro-thermal-mechanical coupling

Abstract

The application provides a battery thermal runaway analysis method and device based on electric-thermal-force coupling, and belongs to the technical field of battery safety analysis and failure early warning, and comprises the following steps: S1, constructing a mechanism model; S2, defining an initial state vector and a core characteristic parameter set; S3, simultaneously performing temperature rising, pressure application and charge-discharge test on the battery; S4, collecting actual measurement values in real time; S5, the mechanism model outputs model output values; S6, constructing a target error function; S7, calculating a deviation; S8, setting a threshold value, if the deviation is less than the threshold value, the core characteristic parameter set data is used as a real physical characteristic parameter for describing the battery; if the deviation is greater than or equal to the threshold value, an optimization algorithm is used for updating, and the updated core characteristic parameter set data is used as a real physical characteristic parameter for describing the battery; and S9, analysis. The method can be used for experimental research under thermal abuse, electric abuse and mechanical abuse of various batteries, and provides extremely solid theoretical support for the safety prevention design of the battery.

Description

Technical Field

[0001] This invention relates to the field of battery safety analysis and failure early warning technology, specifically to a battery thermal runaway analysis method and device based on electro-thermal-mechanical coupling. Background Technology

[0002] Lithium-ion batteries can experience thermal runaway under extreme conditions, where the internal temperature of the battery rises rapidly, causing uncontrolled chemical reactions and potentially leading to catastrophic consequences such as fires and explosions. Thermal runaway in lithium-ion batteries is essentially a complex multi-physics coupling process involving the interaction of multiple factors, including electrical, thermal, and mechanical forces. Therefore, accurate analysis of thermal runaway in lithium batteries is crucial.

[0003] Currently, research and testing equipment for battery safety (such as adiabatic accelerated calorimeters and extrusion needle penetration testers) often have limited functionality. They can typically only independently simulate single-dimensional abuse conditions such as thermodynamics or mechanics, making it difficult to realistically reproduce the harsh service conditions of batteries under the multi-field coupling of electro-thermal-mechanical fields in actual systems in a laboratory environment. This leads to significant discrepancies between existing test results and the actual safety evolution behavior of battery systems. More importantly, even with some multi-dimensional test data, existing research methods often only analyze apparent phenomena and experimental curves. Due to the lack of in-depth electro-thermal-mechanical coupling mechanism models, researchers find it difficult to extract core physical parameters (such as thermo-mechanical equivalent elastic modulus, side reaction activation energy, and dynamic contact internal resistance) that reflect the true degradation and failure mechanisms within the battery from macroscopic test data. This makes it difficult for current research on battery thermal runaway to quantitatively decouple the contribution weights of various heat sources at different failure stages, and also fails to clearly elucidate how mechanical constraint boundaries microscopically intervene in the underlying logic of internal thermodynamic runaway.

[0004] Therefore, we propose a battery thermal runaway analysis method and device based on electro-thermal-mechanical coupling. Summary of the Invention

[0005] The purpose of this invention is to provide a battery thermal runaway analysis method and apparatus based on electro-thermal-mechanical coupling, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a battery thermal runaway analysis method based on electro-thermal-mechanical coupling, comprising the following steps:

[0008] S1: Construct an electro-thermal-mechanical coupling mechanism model;

[0009] S2: Define the battery's initial state vector and the set of the battery's core feature parameters;

[0010] S3: Simultaneously perform temperature rise, pressure application, and charge / discharge tests on the battery;

[0011] S4: Real-time acquisition of actual measurement values ​​during battery testing;

[0012] S5: Based on the battery test in step S3, the output value of the electro-thermal-mechanical coupling mechanism model in step S1 is output.

[0013] S6: Construct the target error function;

[0014] S7: Based on the target error function constructed in S6, calculate the deviation between the actual measured value in step S4 and the model output value in step S5;

[0015] S8: Set a threshold. If the deviation is less than the threshold, the set of core feature parameters that match the model output value will be used as the parameters describing the true physical characteristics of the battery.

[0016] If the deviation is greater than or equal to the threshold, the optimization algorithm is used to update the physical parameters in the core feature parameter set until the deviation is less than the threshold. The updated core feature parameter set data is used as the parameters describing the true physical characteristics of the battery.

[0017] S9: Based on the core feature parameter set data identified in step S8, analyze the battery thermal runaway mechanism and failure evolution.

[0018] Furthermore, in step S1, the electro-thermal-mechanical coupling mechanism model is as follows:

[0019] The heat production equation is:

[0020]

[0021] in, Indicates battery quality; Indicates specific heat capacity; This indicates the temperature output by the model; Indicates the excitation current; This indicates internal resistance, which is affected by temperature and pressure. This indicates that the side reaction generates heat; This indicates that the machine generates heat by doing work; Indicates the convective heat transfer coefficient; Indicates the heat dissipation area; Indicates ambient temperature;

[0022] Internal resistance The equation is:

[0023]

[0024] in, Indicates the battery's reference internal resistance; Indicates the activation energy of electrochemical polarization; Represents the ideal gas constant; This indicates the preset calibration temperature; The pressure sensitivity coefficient represents the internal resistance; Indicates pressure;

[0025] Heat generated by side reactions The equation is:

[0026]

[0027] in, It is the pre-exponential factor of the side reaction; Indicates the activation energy of a chemical side reaction;

[0028] Mechanical work generates heat The equation is:

[0029]

[0030] in, The mechanical dissipation coefficient of the battery structure;

[0031] The electrical equations are:

[0032]

[0033] in, This represents the voltage output by the model; This represents the open-circuit voltage, which is affected by the state of charge and temperature. Indicates polarization voltage;

[0034] The mechanical expansion equation is:

[0035]

[0036] in, This represents the pressure output by the model; This represents the battery's equivalent elastic modulus, which is affected by temperature. Indicates the coefficient of thermal expansion; Indicates the chemical expansion coefficient of the battery; Indicates the state of charge;

[0037] Battery equivalent elastic modulus The equation is:

[0038]

[0039] in, The baseline elastic modulus; The temperature sensitivity coefficient of the modulus.

[0040] Furthermore, in step S2, the battery initial state vector Defined as:

[0041]

[0042] in, The initial temperature; This is the initial preload; This is the initial terminal voltage; This is the initial state of charge;

[0043] The core characteristic parameter set of batteries Including electrochemical polarization activation energy Pressure sensitivity coefficient of internal resistance Reference elastic modulus Temperature sensitivity coefficient of modulus Pre-exponential factors of side reactions Activation energy of chemical side reactions Mechanical dissipation coefficient of battery structure .

[0044] Furthermore, in step S3, the temperature rise test satisfies:

[0045]

[0046] in, The set heating rate; Indicates the target temperature;

[0047] The pressure test ensures that the pressure remains constant after being applied to a preset value.

[0048] The charge and discharge test meets the requirement of repeatedly charging and discharging the battery at a preset frequency.

[0049] Furthermore, in step S4, the actual measured values ​​include the battery surface temperature. Surface contact pressure Terminal voltage and excitation current .

[0050] Furthermore, in step S5, the model output values ​​include temperature. ,Voltage and pressure .

[0051] Furthermore, in step S6, the target error function is:

[0052]

[0053] in, Indicates deviation; , , These are dimensionless weighting coefficients.

[0054] Furthermore, in step S8, the optimization algorithm is one of the following: nonlinear least squares method, genetic algorithm, or particle swarm optimization algorithm.

[0055] Furthermore, in step S9, the analysis of battery thermal runaway mechanism and failure evolution includes decoupling of multi-field heat generation contribution, electro-thermal-mechanical coupling failure law, and assessment of the influence of mechanical constraint boundary.

[0056] Furthermore, this invention provides a battery thermal runaway analysis device based on electro-thermal-mechanical coupling, comprising a lower pressure plate and a nut. The lower pressure plate is provided with a fixing bolt, which is fixedly connected to the lower pressure plate. The end of the fixing bolt away from the lower pressure plate is threadedly connected to an upper pressure plate. The upper pressure plate is mounted on the fixing bolt by a nut. The upper pressure plate is provided with a threaded screw unit, which is threadedly connected to the upper pressure plate. The bottom of the threaded screw unit is threadedly connected to a threaded sleeve. A pressure block is fixedly provided at the bottom of the threaded sleeve. A thin-film pressure sensor is provided at the bottom of the pressure block. The thin-film pressure sensor is electrically connected to a control terminal.

[0057] An experimental battery is placed on the lower pressure plate. The bottom of the experimental battery is provided with a lower clamping plate, and the top of the experimental battery is provided with an upper clamping plate. Heating wires are embedded inside both the upper and lower clamping plates, and the heating wires are electrically connected to the control terminal.

[0058] The lower clamping plate and the upper clamping plate are connected by a positioning screw. The bottom of the lower clamping plate is provided with a lower heat insulation pad, and the top of the upper clamping plate is provided with an upper heat insulation pad. Temperature sensors are provided on the surface of the experimental battery, the lower clamping plate, and the upper clamping plate. The temperature sensors are electrically connected to a control terminal. The experimental battery is electrically connected to an external electrochemical workstation, and the external electrochemical workstation is electrically connected to the control terminal.

[0059] Compared with the prior art, the present invention has the following technical effects:

[0060] 1. In this invention, the method simultaneously applies three loads to the battery: electrical (charging and discharging), thermal (heating), and mechanical (pressure application). This allows for a realistic reconstruction of the complex operating and failure environment of the battery under actual working conditions. By constructing an electro-thermal-mechanical coupling mechanism model, it overcomes the limitation of traditional tests that can only obtain apparent curves. It enables the acquisition and identification of implicit physical parameters such as activation energy and equivalent modulus within the battery. Based on the identified real physical parameters, it quantitatively decouples the weights of ohmic heat generation, side reaction heat generation, and mechanical work heat generation at different temperature stages. It also elucidates the critical mechanism of separator failure caused by electro-thermal-mechanical interaction. This method can be used for experimental research under various battery thermal abuse, electrical abuse, and mechanical abuse conditions, providing extremely solid theoretical support for battery safety design.

[0061] 2. In this invention, the device is highly versatile and can be applied to batteries of various configurations such as pouch and prismatic. Attached Figure Description

[0062] Figure 1 This is a flowchart illustrating the analysis method according to an embodiment of the present invention;

[0063] Figure 2 This is a schematic diagram of the overall structure of the analysis device according to an embodiment of the present invention;

[0064] Figure 3 This is a schematic diagram of the upper and lower pressure plates according to an embodiment of the present invention;

[0065] Figure 4 This is a schematic diagram of the upper and lower clamping plates in an embodiment of the present invention.

[0066] In the diagram: 1. Experimental battery, 2. Upper pressure plate, 3. Lower pressure plate, 4. Threaded screw unit, 5. Threaded sleeve, 6. Pressure block, 7. Thin-film pressure sensor, 8. Pressure sensor wiring, 9. Nut, 10. Fixing bolt, 11. Upper heat insulation pad, 12. Lower heat insulation pad, 13. Positioning screw, 14. Upper clamping plate, 15. Lower clamping plate, 16. Heating wire, 17. Clamping plate power cord, 18. Control terminal, 19. Temperature sensor. Detailed Implementation

[0067] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0068] In this article, terms such as "left," "right," "up," "down," "front," and "back" are established based on the positional relationships shown in the attached drawings. Depending on the attached drawings, the corresponding positional relationships may also change. Therefore, they should not be interpreted as an absolute limitation on the scope of protection.

[0069] Please see Figure 1 This embodiment provides a battery thermal runaway analysis method based on electro-thermal-mechanical coupling, including the following steps:

[0070] S1: Construct an electro-thermal-mechanical coupling mechanism model.

[0071] Specifically, in step S1, the electro-thermal-mechanical coupling mechanism model is as follows:

[0072] The heat production equation is:

[0073]

[0074] in, Indicates battery quality; Indicates specific heat capacity; This indicates the temperature output by the model; Indicates the excitation current; This indicates internal resistance, which is affected by temperature and pressure. This indicates that the side reaction generates heat; This indicates that the machine generates heat by doing work; Indicates the convective heat transfer coefficient; Indicates the heat dissipation area; Indicates ambient temperature;

[0075] This equation reflects the combined effects of heat generation from ohmic polarization, heat generation from side reactions, and heat generation from mechanical work.

[0076] Internal resistance The equation is:

[0077]

[0078] in, Indicates the battery's reference internal resistance; Indicates the activation energy of electrochemical polarization; Represents the ideal gas constant; This indicates the preset calibration temperature; The pressure sensitivity coefficient represents the internal resistance; Indicates pressure;

[0079] Heat generated by side reactions The equation is:

[0080]

[0081] in, It is the pre-exponential factor of the side reaction; Indicates the activation energy of a chemical side reaction;

[0082] Mechanical work generates heat The equation is:

[0083]

[0084] in, The mechanical dissipation coefficient of the battery structure;

[0085] The electrical equations are:

[0086]

[0087] in, This represents the voltage output by the model; This represents the open-circuit voltage, which is affected by the state of charge and temperature, and depends on the battery's chemical system. It can be calculated using a lookup table or polynomial fitting. Indicates polarization voltage;

[0088] The mechanical expansion equation is:

[0089]

[0090] in, This represents the pressure output by the model; This represents the battery's equivalent elastic modulus, which is affected by temperature. Indicates the coefficient of thermal expansion; Indicates the chemical expansion coefficient of the battery; Indicates the state of charge;

[0091] Battery equivalent elastic modulus The equation is:

[0092]

[0093] in, The baseline elastic modulus; The temperature sensitivity coefficient of the modulus.

[0094] S2: Define the battery's initial state vector and the set of core feature parameters of the battery.

[0095] Specifically, in step S2, the battery initial state vector Defined as:

[0096]

[0097] in, The initial temperature; This is the initial preload; This is the initial terminal voltage; This is the initial state of charge;

[0098] The core characteristic parameter set of batteries Including electrochemical polarization activation energy Pressure sensitivity coefficient of internal resistance Reference elastic modulus Temperature sensitivity coefficient of modulus Pre-exponential factors of side reactions Activation energy of chemical side reactions Mechanical dissipation coefficient of battery structure These parameters are not fixed constants, but rather underlying intrinsic coefficients that control the dynamic evolution of the electro-thermal-mechanical coupling mechanism model. Through these underlying intrinsic coefficients, the model can automatically adapt to the time-varying characteristics of parameters under different temperatures and pressures, thereby ensuring high accuracy in the analysis of thermal runaway mechanisms and failure evolution.

[0099] S3: Simultaneously perform heating, pressure application, and charge / discharge tests on the battery.

[0100] Specifically, in step S3, the temperature rise test satisfies:

[0101]

[0102] in, The set heating rate (e.g., 5℃ / min); Indicates the target temperature;

[0103] The pressure test ensures that the pressure remains constant after reaching a preset value, thus simulating the rigid constraints in a real battery pack. The preset value needs to be set according to actual conditions. At this point, the battery's thermal and chemical expansion will translate into a drastic change in contact pressure, which is measured in step S4 using the surface contact pressure. These are the actual measurement indicators.

[0104] The charge-discharge test involves repeatedly charging and discharging the battery at a preset frequency to stimulate the electrochemical polarization response within the battery. The charge-discharge test can be performed using an external electrochemical workstation. The preset frequency needs to be set according to actual conditions.

[0105] S4: Real-time acquisition of actual measurement values ​​during battery testing. Actual measurement values ​​include battery surface temperature. Surface contact pressure Terminal voltage and excitation current .

[0106] S5: Based on the battery test in step S3, the electro-thermal-mechanical coupling mechanism model from step S1 outputs its values. The model output values ​​include temperature. ,Voltage and pressure .

[0107] S6: Construct the target error function.

[0108] Specifically, in step S6, the target error function is:

[0109]

[0110] in, Indicates deviation; 、 、 These are dimensionless weighting coefficients used to eliminate differences in magnitude and dimensions between temperature, pressure, and voltage. In practical calculations, 、 、 The values ​​can be taken as the reciprocal of the square of the maximum value of the corresponding physical quantity experimental data.

[0111] S7: Based on the target error function constructed in S6, calculate the deviation between the actual measured value in step S4 and the model output value in step S5.

[0112] S8: Set a threshold. If the deviation is less than the threshold, the set of core feature parameters that match the model output value will be used as the parameters describing the true physical characteristics of the battery.

[0113] If the deviation is greater than or equal to the threshold, an optimization algorithm is used to update the physical parameters in the core feature parameter set until the deviation is less than the threshold. The updated core feature parameter set data is then used as the parameters describing the true physical characteristics of the battery.

[0114] Specifically, in step S8, the optimization algorithm is one of the following: nonlinear least squares method, genetic algorithm, or particle swarm optimization algorithm. The threshold value needs to be set according to the actual situation.

[0115] S9: Based on the core feature parameter set data identified in step S8, analyze the battery thermal runaway mechanism and failure evolution.

[0116] Specifically, in step S9, the analysis of battery thermal runaway mechanism and failure evolution includes decoupling of multi-field heat generation contribution, electro-thermal-mechanical coupling failure law, and assessment of the influence of mechanical constraint boundary.

[0117] Decoupling of multiple heat generation contributions: By combining the core characteristic parameter set data with the electro-thermal-mechanical coupling mechanism model, the time series of various heat generation powers are obtained, thereby quantitatively analyzing the weights of ohmic polarization heat generation, heat generation from different chemical side reactions, and heat generation from mechanical stress work in different temperature ranges of battery failure, revealing the core mechanism that dominates the thermal runaway chain reaction.

[0118] Electro-thermal-mechanical coupling failure law: By identifying the dynamic change curves of elastic modulus and internal resistance, the correspondence between the pressure change characteristics and voltage drop characteristics output by the model on the time axis is analyzed, and then the critical conditions for diaphragm failure under specific mechanical loads are determined.

[0119] Mechanical constraint boundary impact assessment: By comparing the core characteristic parameter set data of the same battery under different initial pre-tightening force test conditions, we can deeply analyze how the external rigid constraint environment can exacerbate or delay the thermal runaway process of the battery by changing the porosity of the electrode and the internal stress distribution, thus providing underlying physical mechanism support for the mechanical explosion-proof design and stress release strategy of battery modules.

[0120] Specifically, this method simultaneously applies three loads to the battery: electrical (charging and discharging), thermal (heating), and mechanical (pressure application). This allows for a realistic reconstruction of the complex operating and failure environments of the battery under actual conditions. By constructing an electro-thermal-mechanical coupling mechanism model, it overcomes the limitation of traditional tests that can only obtain apparent curves. This enables the acquisition and identification of implicit physical parameters such as the battery's activation energy and equivalent modulus. Based on the identified real physical parameters, it quantitatively decouples the weights of ohmic heat generation, side reaction heat generation, and mechanical work heat generation at different temperature stages. Furthermore, it elucidates the critical mechanism of separator failure caused by electro-thermal-mechanical interaction. This method can be used for experimental research under various battery thermal abuse, electrical abuse, and mechanical abuse conditions, providing extremely solid theoretical support for battery safety design.

[0121] Please see Figures 2 to 4 This embodiment also provides a battery thermal runaway analysis device based on electro-thermal-mechanical coupling, including a lower pressure plate 3 and nuts 9, with the lower pressure plate 3 serving as a base. Fixing bolts 10 are provided at the four corners of the lower pressure plate 3, and the fixing bolts 10 are fixedly connected to the lower pressure plate 3. An upper pressure plate 2 is threadedly connected to the end of the fixing bolt 10 away from the lower pressure plate 3. The upper pressure plate 2 is mounted on the fixing bolts 10 by nuts 9, which are used to limit and adjust the vertical movement of the upper pressure plate 2. The upper pressure plate 2 can move up and down along the fixing bolts 10, and when it reaches a designated position, it is locked in place by the nuts 9.

[0122] Specifically, the upper pressure plate 2 is equipped with a threaded screw unit 4, which is threadedly connected to the upper pressure plate 2. A threaded sleeve 5 is threadedly connected to the bottom of the threaded screw unit 4. A pressure block 6 is fixedly mounted on the bottom of the threaded sleeve 5, and a thin-film pressure sensor 7 is mounted on the bottom of the pressure block 6. The thin-film pressure sensor 7 is electrically connected to a control terminal 18 via a pressure sensor wiring 8. The thin-film pressure sensor 7 is used to monitor the pressure changes on the battery surface in real time, and the monitoring data from the thin-film pressure sensor 7 is transmitted to the control terminal 18. A handwheel is located at the top of the threaded screw unit 4. During operation, a manual mechanical pressurization method is used. When the operator rotates the handwheel, the threaded screw unit 4 can drive the threaded sleeve 5 and the pressure block 6 to move downwards in the vertical direction, thereby achieving controllable pre-tightening force (i.e., pressure) loading on the battery.

[0123] Specifically, an experimental battery 1 is placed on the lower pressure plate 3. A lower clamping plate 15 is located at the bottom of the experimental battery 1, and an upper clamping plate 14 is located at the top of the experimental battery 1. The upper clamping plate 14 and the lower clamping plate 15 are used to clamp and fix the experimental battery 1. Heating wires 16 are embedded inside both the upper clamping plate 14 and the lower clamping plate 15. The heating wires 16 are electrically connected to the control terminal 18 via a clamping plate power cable 17. The control terminal 18 can control the heating wires 16 to perform heating tests on the experimental battery 1.

[0124] Specifically, the lower clamping plate 15 and the upper clamping plate 14 are connected by a positioning screw 13. A lower heat insulation pad 12 is provided at the bottom of the lower clamping plate 15, and an upper heat insulation pad 11 is provided at the top of the upper clamping plate 14. The lower heat insulation pad 12 and the upper heat insulation pad 11 are used to prevent heat conduction to other components of the device during testing. Temperature sensors are provided on the surface of the experimental battery 1, the lower clamping plate 15, and the upper clamping plate 14. The temperature sensors are used to monitor the temperature of the upper clamping plate 14, the lower clamping plate 15, and the battery surface in real time. Platinum resistance temperature sensors can be used. The temperature sensors are electrically connected to the control terminal 18, and the monitoring data from the temperature sensors is transmitted to the control terminal 18.

[0125] Specifically, experimental battery 1 is electrically connected to an external electrochemical workstation, which performs charge-discharge tests, voltage and current monitoring, and electrochemical impedance spectroscopy measurements on the battery. The external electrochemical workstation is electrically connected to control terminal 18, and its monitoring data is transmitted to control terminal 18. Control terminal 18 can coordinate and control the entire experimental process, controlling the application and maintenance of preload, executing the programmed temperature rise process, and simultaneously acquiring, recording, and processing pressure, temperature, and electrochemical data, thereby achieving automatic control of the entire testing process.

[0126] Specifically, this device is highly versatile and can be applied to batteries of various configurations, such as pouch and prismatic.

[0127] The above embodiments merely illustrate the basic principles and characteristics of the present invention, but are not limited to the above implementation schemes. It should be understood that those skilled in the art can make various changes and modifications to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A battery thermal runaway analysis method based on electro-thermal-mechanical coupling, characterized in that, Includes the following steps: S1: Construct an electro-thermal-mechanical coupling mechanism model; In step S1, the electro-thermal-mechanical coupling mechanism model is as follows: The heat production equation is: wherein, represents the battery mass; represents the specific heat capacity; represents the temperature output by the model; represents the excitation current; represents the internal resistance, influenced by temperature and pressure; represents the side reaction heat production; represents the mechanical work production heat; represents the convective heat transfer coefficient; represents the heat dissipation area; represents the ambient temperature; Internal resistance The equation is: in, Indicates the battery's reference internal resistance; Indicates the activation energy of electrochemical polarization; Represents the ideal gas constant; This indicates the preset calibration temperature; The pressure sensitivity coefficient represents the internal resistance; Indicates pressure; Heat generated by side reactions The equation is: in, It is the pre-exponential factor of the side reaction; Indicates the activation energy of a chemical side reaction; Mechanical work generates heat The equation is: in, The mechanical dissipation coefficient of the battery structure; The electrical equations are: in, This represents the voltage output by the model; This represents the open-circuit voltage, which is affected by the state of charge and temperature. Indicates polarization voltage; The mechanical expansion equation is: in, This represents the pressure output by the model; This represents the battery's equivalent elastic modulus, which is affected by temperature. Indicates the coefficient of thermal expansion; Indicates the chemical expansion coefficient of the battery; Indicates the state of charge; Battery equivalent elastic modulus The equation is: in, The baseline elastic modulus; The temperature sensitivity coefficient of the modulus; S2: Define the battery's initial state vector and the set of the battery's core feature parameters; S3: Simultaneously perform temperature rise, pressure application, and charge / discharge tests on the battery; S4: Real-time acquisition of actual measurement values ​​during battery testing; S5: Based on the battery test in step S3, the output value of the electro-thermal-mechanical coupling mechanism model in step S1 is output. S6: Construct the target error function; S7: Based on the target error function constructed in S6, calculate the deviation between the actual measured value in step S4 and the model output value in step S5; S8: Set a threshold. If the deviation is less than the threshold, the set of core feature parameters that match the model output value will be used as the parameters describing the true physical characteristics of the battery. If the deviation is greater than or equal to the threshold, the optimization algorithm is used to update the physical parameters in the core feature parameter set until the deviation is less than the threshold. The updated core feature parameter set data is used as the parameters describing the true physical characteristics of the battery. S9: Based on the core feature parameter set data identified in step S8, analyze the battery thermal runaway mechanism and failure evolution.

2. The battery thermal runaway analysis method based on electro-thermal-mechanical coupling according to claim 1, characterized in that, In step S2, the battery initial state vector Defined as: in, The initial temperature; This is the initial preload; This is the initial terminal voltage; This is the initial state of charge; The core characteristic parameter set of batteries Including electrochemical polarization activation energy Pressure sensitivity coefficient of internal resistance Reference elastic modulus Temperature sensitivity coefficient of modulus Pre-exponential factors of side reactions Activation energy of chemical side reactions Mechanical dissipation coefficient of battery structure .

3. The battery thermal runaway analysis method based on electro-thermal-mechanical coupling according to claim 1, characterized in that, In step S3, the temperature rise test satisfies: in, The set heating rate; Indicates the target temperature; The pressure test ensures that the pressure remains constant after being applied to a preset value. The charge and discharge test meets the requirement of repeatedly charging and discharging the battery at a preset frequency.

4. The battery thermal runaway analysis method based on electro-thermal-mechanical coupling according to claim 3, characterized in that, In step S4, the actual measured values ​​include the battery surface temperature. Surface contact pressure Terminal voltage and excitation current .

5. The battery thermal runaway analysis method based on electro-thermal-mechanical coupling according to claim 1, characterized in that, In step S5, the model output values ​​include temperature. ,Voltage and pressure .

6. The battery thermal runaway analysis method based on electro-thermal-mechanical coupling according to claim 1, characterized in that, In step S6, the target error function is: in, Indicates deviation; , , These are dimensionless weighting coefficients.

7. The battery thermal runaway analysis method based on electro-thermal-mechanical coupling according to claim 1, characterized in that, In step S8, the optimization algorithm is one of the following: nonlinear least squares method, genetic algorithm, or particle swarm optimization algorithm.

8. The battery thermal runaway analysis method based on electro-thermal-mechanical coupling according to claim 1, characterized in that, In step S9, the analysis of battery thermal runaway mechanism and failure evolution includes decoupling of multi-field heat generation contribution, electro-thermal-mechanical coupling failure law, and assessment of the influence of mechanical constraint boundary.

9. A battery thermal runaway analysis device based on electro-thermal-mechanical coupling, the device being used to implement the battery thermal runaway analysis method based on electro-thermal-mechanical coupling as described in any one of claims 1-8, characterized in that, Includes a lower pressure plate (3) and a nut (9). The lower pressure plate (3) is provided with a fixing bolt (10), which is fixedly connected to the lower pressure plate (3). The end of the fixing bolt (10) away from the lower pressure plate (3) is threadedly connected to an upper pressure plate (2). The upper pressure plate (2) is installed on the fixing bolt (10) by the nut (9). The upper pressure plate (2) is provided with a threaded screw unit (4), which is threadedly connected to the upper pressure plate (2). The bottom of the threaded screw unit (4) is threadedly connected to a threaded sleeve (5). The bottom of the threaded sleeve (5) is fixedly provided with a pressure block (6). The bottom of the pressure block (6) is provided with a thin film pressure sensor (7), which is electrically connected to a control terminal (18). The experimental battery (1) is placed on the lower pressure plate (3). The bottom of the experimental battery (1) is provided with a lower clamping plate (15) and the top of the experimental battery (1) is provided with an upper clamping plate (14). Heating wires (16) are embedded inside the upper clamping plate (14) and the lower clamping plate (15). The heating wires (16) are electrically connected to the control terminal (18). The lower clamping plate (15) and the upper clamping plate (14) are connected by a positioning screw (13). The lower clamping plate (15) is provided with a lower heat insulation pad (12) at the bottom and the upper clamping plate (14) is provided with an upper heat insulation pad (11) at the top. Temperature sensors are provided on the surface of the experimental battery (1), the lower clamping plate (15) and the upper clamping plate (14). The temperature sensors are electrically connected to the control terminal (18). The experimental battery (1) is electrically connected to an external electrochemical workstation. The external electrochemical workstation is electrically connected to the control terminal (18).

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