Test method for battery thermal runaway

Abstract

The application provides a test method for thermal runaway of an electric core, comprising the following steps: step S10, embedding a heating element at a preset trigger position of the electric core to be tested, the preset trigger position being selected from a tab root, a core center or an electrode edge; step S20, arranging a temperature sensor at a preset temperature measurement position of the electric core to be tested, and arranging a pressure sensor on an outer surface of the electric core to be tested, so as to complete preparation of a test sample; and step S30, leading out a lead wire of the heating element from the electric core and connecting the lead wire to a programmable power supply, so as to apply controllable electric power by the programmable power supply to make the heating element generate a temperature gradient in a local area of the electric core to be tested, which is sufficient to trigger thermal runaway of the electric core to be tested, so as to simulate a thermal runaway process of the electric core to be tested triggered by an internal heat source. The application solves the problems in the prior art, such as uncontrollable position, mechanism deviation between a process and an actual situation, insufficient repeatability and consistency, limited data monitoring and safety hazards in the process of triggering thermal runaway of a battery.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle battery safety technology, and more specifically, to a test method for battery thermal runaway. Background Technology

[0002] Currently, common methods for triggering thermal runaway in battery cells under laboratory conditions include external heating, needle puncture, and overcharging. External heating involves heating the entire cell or a portion of it using an external heating device (such as a high-temperature chamber, heating plate, or flame jet) until thermal runaway is triggered. Needle puncture involves piercing the cell with a metal needle at a certain speed, causing an internal short circuit and thus inducing thermal runaway. Overcharging involves overcharging or over-discharging the cell with a large current or high voltage, causing a large amount of heat and side reactions inside, ultimately leading to thermal runaway.

[0003] The above-mentioned methods for triggering thermal runaway of battery cells have the following drawbacks:

[0004] 1. Uncontrollable Trigger Location: Existing external heating methods typically heat the entire cell or a large area thereof. This method cannot accurately simulate thermal runaway caused by a specific local hot spot (such as burrs or metallic impurities) inside the cell. Furthermore, the needle-puncture method is limited to using the needle-puncture point as the trigger source, and cannot flexibly select other potentially risky critical locations inside the cell (such as the base of the tab, the center of the winding core, etc.). This limits the simulation and analysis of real thermal runaway scenarios.

[0005] 2. Deviation between the thermal runaway triggering mechanism and actual conditions: The triggering mechanism of the needle penetration method differs from the thermal runaway mechanism caused by the gradual development of internal short circuits in actual use. The overcharge / overdischarge method involves a relatively slow electrochemical process, which does not completely match the violent and instantaneous characteristics of actual thermal runaway. This may limit the test results in reflecting the true failure mode.

[0006] 3. Poor repeatability and consistency: In the needle-punching method, the difficulty in accurately controlling parameters such as needle speed, force, and needle shape leads to poor repeatability between multiple different tests. Similarly, the external heating method, due to uncertainties in factors such as the surface condition of the battery cell and the contact method, can also cause fluctuations in the thermal runaway trigger time and intensity, affecting the reliability of the data and the consistency of the test results.

[0007] 4. Difficulty in data monitoring: In existing testing methods, when using intense external heating or needle penetration, it is difficult to accurately deploy temperature, pressure and other sensors near the trigger point. This makes it difficult to fully capture key data on the initial stage and propagation process of thermal runaway, affecting in-depth understanding and research on the mechanism of thermal runaway.

[0008] 5. Safety issues: Some existing testing methods, such as the needle penetration and overcharge methods, have certain safety hazards. For example, needle penetration may generate sparks, and overcharging may cause the battery cell to explode. This not only poses a threat to test personnel, but may also damage the test equipment, increasing the cost and complexity of the test.

[0009] In summary, existing technologies face challenges in triggering battery thermal runaway, including uncontrollable location, mechanistic discrepancies between the process and actual conditions, insufficient repeatability and consistency, limited data monitoring, and safety hazards. Summary of the Invention

[0010] The main objective of this invention is to provide a test method for battery thermal runaway, in order to solve the problems faced by the prior art in triggering battery thermal runaway, such as uncontrollable location, deviation between the process and the actual situation, insufficient repeatability and consistency, limited data monitoring, and safety hazards.

[0011] To achieve the above objectives, the present invention provides a method for testing the thermal runaway of a battery cell, comprising the following steps: Step S10, embedding a heating element at a preset trigger position of the battery cell under test, wherein the preset trigger position is selected from the root of the tab, the center of the core, or the edge of the electrode sheet; Step S20, arranging a temperature sensor at a preset temperature measurement position of the battery cell under test, and arranging a pressure sensor on the outer surface of the battery cell under test, to complete the preparation of the test sample; Step S30, leading the heating element out of the battery cell under test and connecting it to a programmable power supply, so as to apply controllable electrical power through the programmable power supply to generate a temperature gradient in a local area of ​​the battery cell under test that is sufficient to induce its thermal runaway, thereby simulating the thermal runaway process of the battery cell under test caused by its internal heat source.

[0012] In an exemplary embodiment, in step S30, the programmable power supply controls the heating power, heating duration, and heating curve of the heating element, wherein the heating curve includes stepped heating, constant power heating, or pulse heating.

[0013] In an exemplary embodiment, after step S10 and before step S20, the test method further includes step S11, which involves encapsulating the lead wire at the lead-out position of the cell under test.

[0014] In one exemplary embodiment, the preset temperature measurement location includes at least the heating element inside the battery cell under test, the positive and negative terminals of the battery cell under test, the explosion-proof valve of the battery cell under test, and the two large surfaces of the battery cell under test that are arranged opposite to each other; and / or, the pressure sensor is located at the two large surfaces of the battery cell under test that are arranged opposite to each other.

[0015] In one exemplary embodiment, the battery cell under test is placed in a sealed, pressure-resistant test chamber with pressure relief function before thermal runaway occurs.

[0016] In an exemplary embodiment, after step S30, the test method further includes step S40, in which, during the temperature rise of the heating element and the thermal runaway process of the battery cell under test, the data acquisition system continuously records the real-time temperature value obtained by the temperature sensor, the real-time pressure value obtained by the pressure sensor, and simultaneously records the real-time voltage value and real-time current value of the battery cell under test; in step S50, the real-time temperature value, real-time pressure value, real-time voltage value, and real-time current value are compared and analyzed with the initial parameters of the battery cell under test to obtain the key parameters of thermal runaway of the battery cell under test.

[0017] In an exemplary embodiment, the real-time internal resistance value of the battery cell under test is obtained based on the real-time voltage value and the real-time current value; in step S50, the acquisition of the initial parameters of the battery cell under test includes the data acquisition system recording the initial voltage, initial internal resistance, and initial temperature of the battery cell under test before the programmable power supply powers on the heating element; comparing the initial voltage with the real-time voltage value, comparing the initial internal resistance with the real-time internal resistance value, and comparing the initial temperature with the real-time temperature value.

[0018] In an exemplary embodiment, the key parameters of thermal runaway of the battery cell under test include at least the thermal runaway trigger temperature, the maximum thermal runaway temperature, the temperature rise rate, the pressure rise rate, the voltage drop time, and the thermal runaway propagation speed.

[0019] In one exemplary embodiment, the thermal runaway trigger temperature ranges from 200°C to 300°C.

[0020] In an exemplary embodiment, in step S40, the test method further includes recording flame information, smoke information, and debris ejection information during the thermal runaway process of the battery cell under test using a high-speed camera.

[0021] In an exemplary embodiment, in step S40, the test method further includes collecting the gas generated during the thermal runaway process of the battery cell under test using a gas composition analyzer.

[0022] By embedding a heating element at the root of the tab, the center of the core, or the edge of the electrode sheet in the battery cell under test (BUT), thermal runaway can be precisely triggered and controlled. The lead wire of the heating element is led out of the BUT and connected to a programmable power supply. The programmable power supply applies controllable electrical power to generate a temperature gradient in a localized area of ​​the BUT sufficient to induce thermal runaway, simulating the thermal runaway process caused by the BUT's internal heat source. Temperature and pressure sensors monitor temperature changes at preset measurement locations and pressure changes on the outer surface of the BUT, respectively. Compared to existing technologies, this testing method significantly improves the controllability of the thermal runaway trigger location, making the study of the thermal runaway mechanism closer to real internal short circuits. It also greatly improves test repeatability and consistency, providing more accurate data support for battery management system design and improving the safety of the BUT. More importantly, this method enhances data monitoring capabilities, capturing detailed temperature and pressure changes in the early stages of thermal runaway, thus deepening the understanding of the evolution mechanism of thermal runaway. In summary, the technical solution of this application effectively solves the problems of inaccurate positioning, mechanism deviation, and low data quality in thermal runaway testing, bringing substantial progress to scientific research in the field of battery safety. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0024] Figure 1 A schematic flowchart of a test method for thermal runaway of a battery cell according to an optional embodiment of the present invention is shown. Detailed Implementation

[0025] 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 some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] To address the problems in existing technologies regarding uncontrollable location, mechanistic deviations from actual conditions, insufficient repeatability and consistency, limited data monitoring, and safety hazards during battery thermal runaway, this invention provides a test method for battery cell thermal runaway.

[0027] like Figure 1As shown, the test method for thermal runaway of battery cells includes the following steps:

[0028] Step S10: Embed a heating element at a preset trigger position of the cell to be tested. The preset trigger position is selected from the root of the tab, the center of the core, or the edge of the electrode sheet.

[0029] Step S20: A temperature sensor is placed at a preset temperature measurement position on the battery cell to be tested, and a pressure sensor is placed on the outer surface of the battery cell to be tested, so as to complete the preparation of the test sample.

[0030] Step S30: Lead the heating element out of the battery cell under test and connect it to a programmable power supply. Apply controllable power through the programmable power supply to generate a temperature gradient in a local area of ​​the battery cell under test that is sufficient to induce thermal runaway, so as to simulate the thermal runaway process caused by the internal heat source of the battery cell under test.

[0031] By embedding heating elements at the root of the tabs, the center of the core, or the edge of the electrode sheet in the battery cell under test (BUT), thermal runaway can be precisely triggered and controlled. The leads of the heating elements are led out of the BUT and connected to a programmable power supply. The programmable power supply applies controllable electrical power to generate a temperature gradient in a localized area of ​​the BUT sufficient to induce thermal runaway, simulating the thermal runaway process caused by the internal heat source. Temperature and pressure sensors monitor temperature changes at preset measurement locations and pressure changes on the outer surface of the BUT, respectively. Compared to existing technologies, this testing method significantly improves the controllability of the thermal runaway trigger location, making the study of the thermal runaway mechanism closer to real internal short circuit scenarios. It also greatly improves test repeatability and consistency, providing more accurate data support for battery management system design and improving the safety of BUT cells. More importantly, this method enhances data monitoring capabilities, capturing detailed temperature and pressure changes in the early stages of thermal runaway, thus deepening the understanding of the evolution mechanism of thermal runaway. In summary, the technical solution of this application effectively solves the problems of inaccurate positioning, mechanism deviation, and low data quality in thermal runaway testing, bringing substantial progress to scientific research in the field of battery safety.

[0032] The detailed steps of the test method for battery cell thermal runaway include:

[0033] Step S10: Place the heating element at the preset trigger position of the battery cell under test, and lead the heating element out of the battery cell under test so that the lead is electrically connected to the programmable power supply.

[0034] Step S20: Set a temperature sensor at a preset temperature measurement position on the battery cell to be tested, and set a pressure sensor on the outer surface of the battery cell to be tested, so as to complete the preparation of the test sample.

[0035] Step S30: Place the test sample into the test chamber, and adjust the heating parameters of the heating element with the programmable power supply so that the temperature of the heating element rises to the thermal runaway trigger temperature and triggers the thermal runaway of the battery cell under test. The thermal runaway continues for a preset time until the reaction in the battery cell under test ends.

[0036] In step S40, during the temperature rise of the heating element and during the thermal runaway of the battery cell under test, the data acquisition system continuously records the real-time temperature value obtained by the temperature sensor and the real-time pressure value obtained by the pressure sensor, and simultaneously records the real-time voltage value and real-time current value of the battery cell under test.

[0037] Step S50: Compare and analyze the real-time temperature, pressure, voltage, and current values ​​recorded by the data acquisition system with the initial parameters of the battery cell under test to obtain the key parameters for thermal runaway of the battery cell under test.

[0038] It should be noted that in step S30 of this application, the programmable power supply controls the heating power, heating duration and heating curve of the heating element, wherein the heating curve includes stepped heating, constant power heating or pulse heating.

[0039] It should be noted that in this application, the preset trigger locations include the base of the tab, the center of the core, and the edge of the electrode sheet. This allows for the triggering of thermal runaway using miniature heating elements embedded in specific locations within the battery cell under test. Specifically, the heating elements can be thin-film heaters or heating wires, strategically positioned at critical locations within the battery cell under test, such as the base of the tab, the center of the core, or the edge of the electrode sheet. This method simulates thermal runaway caused by localized overheating within the battery cell under test by precisely controlling the heating power and time, thus more realistically reproducing the thermal runaway triggering scenarios that may be encountered in real-world applications. This testing method allows for internal heating of the battery cell under test in a closed and controlled environment, improving test safety and ensuring high-quality data, as sensors can be directly placed at the source of thermal runaway to acquire data on changes in key temperature, pressure, and other environmental parameters. Through precise energy input, a series of parameters regarding thermal runaway characteristics can be obtained, such as trigger temperature, maximum temperature rise rate, peak pressure, and thermal runaway propagation speed. This data is crucial for a deeper understanding of thermal runaway mechanisms, evaluating the thermal stability of the battery cell under test, and developing effective thermal management strategies. Furthermore, this internal heating triggering method significantly enhances the repeatability and consistency of the experiment compared to traditional needle penetration or external heating methods, as it eliminates variations caused by uncertainties such as needle penetration speed, force, and external heat source distribution. In summary, this application provides a more accurate, controllable, and safer method for testing battery thermal runaway, offering strong support for the safety of battery design, manufacturing, and use.

[0040] Thermal runaway is precisely triggered and controlled by a heating element pre-positioned at a specific location inside the battery cell under test. The heating element is electrically connected to a programmable power supply. By adjusting the heating parameters, the local temperature inside the battery cell is raised to the thermal runaway trigger temperature, thus triggering thermal runaway. This process takes place within a sealed test chamber to ensure safety. Temperature and pressure sensors monitor temperature changes at preset temperature measurement locations and pressure changes on the outer surface of the battery cell, respectively. The voltage and current of the battery cell are recorded in real time by a data acquisition system. These data collectively depict a complete dynamic picture of thermal runaway from its inception to its outbreak. When the heating element is activated, the temperature inside the battery cell begins to rise. Once the thermal runaway trigger temperature is reached and maintained for a certain period, thermal runaway is triggered. The trends of real-time temperature, pressure, voltage, and current values ​​recorded by the data acquisition system are compared with the initial state of the battery cell to reveal key parameters during the thermal runaway process, such as trigger temperature, maximum temperature, temperature rise rate, pressure rise rate, and voltage drop time. Compared to existing technologies, this testing method significantly improves the controllability of the thermal runaway trigger location, making the study of thermal runaway mechanisms closer to real internal short circuit scenarios. It also greatly improves test repeatability and consistency, providing more accurate data support for battery management system design and enhancing the safety of the cells under test. More importantly, this method enhances data monitoring capabilities, enabling the capture of detailed temperature and pressure changes in the early stages of thermal runaway, thus deepening the understanding of the evolution mechanism of thermal runaway. In summary, the technical solution of this application effectively solves the problems of inaccurate location, mechanism deviation, and low data quality in thermal runaway testing, bringing substantial progress to scientific research in the field of battery safety.

[0041] It should be noted that in this application, after step S10 and before step S20, the test method also includes step S11, which encapsulates the lead wires at the lead-out positions of the battery cell under test. Thus, after the crucial step S10 of pre-positioning the heating element inside the battery cell, the test method adds step S11, specifically for additional encapsulation of the heating element lead wires at their lead-out positions within the battery cell. This measure ensures the structural integrity and electrical isolation of the battery cell during subsequent testing, preventing external interference or accidental short circuits caused by exposed leads, and ensuring precise control of the heating process and the validity of the test results. Subsequently, before activating the heating film or heating wire in step S20, this encapsulation process also provides an additional safety barrier for the battery cell, reducing safety hazards during testing, which is particularly important under extreme conditions involving high temperature and high pressure.

[0042] Furthermore, before the battery cell under test causes thermal runaway, the battery cell under test is placed in a sealed, pressure-resistant test chamber with pressure relief function.

[0043] By implementing step S11, the heating element is more closely integrated with the internal environment of the battery cell. This not only enhances the realism of the test environment, making the triggering of thermal runaway more closely resemble the triggering of internal defects in real-world scenarios, but also improves the repeatability and consistency of the experiment. This provides a more stable and reliable foundation for in-depth analysis of battery thermal runaway mechanisms and evaluation of battery safety designs. Furthermore, the encapsulation process helps improve the quality of data monitoring because sensors placed around the heating element can operate more stably, unaffected by external factors, thereby obtaining more accurate temperature and pressure change curves, as well as real-time dynamics of cell voltage and current. This is crucial for understanding the entire process of thermal runaway from its inception to its full-blown outbreak. Overall, the addition of step S11 improves the entire testing process, providing strong technical support for scientific research and engineering applications in battery safety.

[0044] Furthermore, the preset temperature measurement locations include at least the heating element inside the cell under test, the positive and negative terminals of the cell under test, the explosion-proof valve of the cell under test, and two large surfaces of the cell under test that are positioned opposite each other; and / or, the pressure sensor is located at the two large surfaces of the cell under test that are positioned opposite each other. This refines the battery thermal runaway testing method, with the temperature measurement locations covering at least the heating element inside the cell, the positive and negative terminals of the cell, the explosion-proof valve, and the two large surfaces of the cell 1. This comprehensive temperature measurement layout can accurately capture the occurrence and development dynamics of thermal runaway, especially in the area directly affected by the heating element, and in key areas where thermal runaway may significantly affect the cell structure, such as the positive and negative terminals, the explosion-proof valve, and the large surfaces, ensuring the integrity and reliability of the test data. Simultaneously, the pressure sensor is placed at the two large surfaces of the cell 2, enabling real-time monitoring of pressure changes inside and outside the cell, especially the internal pressure surge generated during thermal runaway. This helps analyze the impact of thermal runaway on the cell's physical structure and evaluate the cell's explosion-proof performance. Overall, this method, through optimization of the temperature measurement locations and pressure sensor layout, achieves multi-dimensional and refined monitoring of the thermal runaway process, providing strong data support for a deeper understanding of the internal thermal runaway mechanism of batteries and for evaluating battery safety performance. In other embodiments not shown, the layout of the temperature measurement locations and pressure sensors can also be adjusted according to specific testing needs to adapt to different types of batteries and different thermal runaway triggering scenarios.

[0045] It should be noted that, in this application, after step S30, the test method further includes: step S40, during the temperature rise of the heating element and the thermal runaway process of the battery cell under test, the data acquisition system continuously records the real-time temperature value obtained by the temperature sensor and the real-time pressure value obtained by the pressure sensor, and simultaneously records the real-time voltage value and real-time current value of the battery cell under test; step S50, the real-time temperature value, real-time pressure value, real-time voltage value, and real-time current value are compared and analyzed with the initial parameters of the battery cell under test to obtain the key parameters of thermal runaway of the battery cell under test.

[0046] Furthermore, the test chamber has sealing, pressure resistance, and pressure relief functions.

[0047] It should be noted that, in this application, the heating parameters include at least heating power and heating time. This allows for precise control of the overheating condition inside the battery cell. By programmably controlling the power and time of the heating film or heating wire, internal heat sources of different intensities and durations can be simulated, thereby reproducing the behavior of the battery cell under various overheating abuse conditions. This gradual energy input method, compared to a one-time high-energy stimulus, more closely resembles the development process of overheating sources in real-world scenarios, contributing to a deeper understanding of the initiation mechanism of thermal runaway and its relationship with the internal structure and materials of the battery cell. Precise control of heating power and time also ensures the repeatability and consistency of the test, making the experimental data more convincing and comparable, thus providing a strong basis for the formulation of battery safety management strategies. Furthermore, this controllable heating process, combined with the safety design of the test chamber, greatly reduces the safety risks during the test, enabling reliable and safe research on thermal runaway phenomena. In other embodiments not shown, the heating parameters may be extended to more detailed dimensions such as temperature profiles and heating modes, further enhancing the flexibility and applicability of the test.

[0048] Furthermore, the heating parameters also include heating curves, which at least include stepped heating and constant power heating.

[0049] It should be noted that in this application, the real-time internal resistance value of the cell under test is obtained based on the real-time voltage and real-time current values. In step S50, the acquisition of the initial parameters of the cell under test includes recording the initial voltage, initial internal resistance, and initial temperature of the cell under test by the data acquisition system before the programmable power supply powers the heating element; comparing the initial voltage with the real-time voltage value, the initial internal resistance with the real-time internal resistance value, and the initial temperature with the real-time temperature value. Thus, for the optimization of the battery thermal runaway testing method, a technical step S40 for real-time monitoring of the cell's internal resistance has been specifically added, accurately obtaining the real-time internal resistance value of the cell under test by analyzing the real-time voltage and real-time current values. In step S50, the process for acquiring the initial parameters of the cell under test is defined more comprehensively, not only recording the initial voltage, internal resistance, and temperature of the cell, but also proposing to compare and analyze these initial values ​​with the values ​​monitored in real-time during the heating process. This design allows us to observe the changes in the cell's state before and after thermal runaway triggering in detail, and to conduct a more in-depth study of the thermal runaway characteristics and mechanisms of the cell. By comparison, abnormal changes in the cell's state after the heating element is energized can be quickly identified, such as voltage drop, increased internal resistance, and temperature rise. These changes are signs of impending thermal runaway and are crucial for assessing the cell's safety performance. Furthermore, this improvement not only enhances the accuracy of test data but also improves experimental safety, as the closed test environment allows for better control and monitoring of potentially hazardous conditions. By precisely controlling the energy input of the heating element and combining it with real-time monitoring of the cell's state, this application achieves a high degree of simulation of thermal runaway triggering conditions, providing strong support for battery safety design and fault prediction. Of course, this technical solution can be applied to various types of cell testing, whether prismatic, cylindrical, or pouch cells, enabling precise and controllable thermal runaway triggering and analysis under similar experimental conditions. In other embodiments not detailed, the design and layout of the heating element and the configuration of the data acquisition system can be further adjusted to suit specific cell types or research objectives, demonstrating the broad applicability and flexibility of this testing method. Changing the position and heating strategy of the heating element by horizontal movement or other means also allows for in-depth exploration of the thermal runaway response in different parts of the cell.

[0050] Furthermore, the key parameters for thermal runaway in the tested battery cell include at least the thermal runaway trigger temperature, the maximum thermal runaway temperature, the temperature rise rate, the pressure rise rate, the voltage drop time, and the thermal runaway propagation speed. Thus, to more accurately assess the battery's thermal runaway characteristics, a micro-heating film or heating wire pre-embedded inside the cell is used as a trigger source, enabling the thermal runaway process to be triggered from a locally overheated area inside the cell. This design can simulate real heat source triggering scenarios caused by impurities or dendrites inside the cell. Compared to traditional external heating and needle penetration methods, it provides more precise and controllable trigger location, energy, and rate, thereby ensuring the consistency and repeatability of the test. By adjusting the electrical power of the heating film through a programmable power supply, internal overheating conditions of varying intensities can be simulated, allowing for a deeper exploration of the thermal runaway triggering mechanism. Simultaneously, this method allows for the deployment of various sensors, such as temperature and pressure sensors, near the thermal runaway initiation point to collect high-quality, high-precision data, which is crucial for understanding and optimizing battery thermal management strategies. Furthermore, placing the test cell in a sealed test chamber not only increases the safety of the test but also provides the possibility of studying the gas release characteristics during thermal runaway and the effectiveness of thermal runaway suppression measures. Therefore, this application not only solves the shortcomings of traditional testing methods but also opens up new avenues for the research and improvement of battery safety performance. Of course, in other embodiments not shown, the type and triggering position of the heating element can be adjusted according to specific testing needs, further enhancing the applicability and flexibility of the testing method. Overall, the scheme described in the claims triggers battery thermal runaway through a built-in heating element, providing strong support for in-depth research on thermal runaway mechanisms and battery safety design.

[0051] It should be noted that in this application, the thermal runaway trigger temperature ranges from 200℃ to 300℃. This temperature range is chosen based on a deep understanding of the battery material characteristics and internal chemical reactions, aiming to simulate thermal runaway caused by localized defects within the battery cell using a built-in heating element. When the heating element receives a preset electrical power, it rapidly heats up to the aforementioned temperature range, sufficient to activate a chain of chemical reactions within the battery cell, such as SEI film decomposition and separator melting, thereby triggering thermal runaway. By precisely controlling the energy input of the heating element, a stable heat source can be generated at a preset key location within the battery cell, thus inducing thermal runaway. This precise triggering method eliminates the uncertainties introduced by traditional testing methods such as external heating or needle penetration, ensuring the consistency and repeatability of each test, and providing a more reliable basis for battery safety performance evaluation. Furthermore, the selection of the preset temperature range also takes into account experimental safety and data validity, ensuring that thermal runaway of the battery cell is triggered in a controlled environment. This also facilitates monitoring the complete process of thermal runaway initiation, development, and termination, thereby obtaining comprehensive thermal runaway characteristic data and providing crucial support for battery design optimization and safety strategy formulation. In other embodiments not shown, the thermal runaway trigger temperature may be adjusted according to specific test requirements or different battery cell materials, but it will always remain within the threshold range capable of inducing a thermal runaway response in the battery cell, in accordance with the original intent and purpose of this invention.

[0052] It should be noted that in this application, in step S40, the testing method further includes recording flame information, smoke information, and debris ejection information during the thermal runaway process of the battery cell under test using a high-speed camera. Thus, when using a high-speed camera to record flame information, smoke information, and debris ejection information during the thermal runaway process of the battery cell under test, we can intuitively observe the dynamic evolution of the thermal runaway event. This recording method is not limited to capturing static data; it allows researchers to analyze visual phenomena during the initiation and development of thermal runaway, including the shape and propagation of flames, changes in the composition and concentration of smoke, and any possible debris dispersion behavior. By integrating a high-speed camera into the testing process, we obtain a multi-dimensional understanding and quantitative analysis of the thermal runaway phenomenon, enhancing our understanding of the internal thermal runaway mechanism of the battery. Furthermore, the retention of video data facilitates subsequent peer review and result reproduction, providing richer and more intuitive evidence for battery safety assessment. Of course, in other embodiments not shown, other non-invasive monitoring technologies, such as infrared thermal imaging and X-ray imaging, can also be combined to further enhance the comprehensive insight into the thermal runaway process and ensure the diversity and reliability of the data. The application of these additional technologies helps to build a more comprehensive testing platform, enabling verification of the effectiveness and safety of thermal runaway triggered by the built-in heating film from multiple angles. It also provides strong support for improving battery design and optimizing thermal management strategies. In other embodiments not shown in the figures, precise monitoring of thermal runaway phenomena at different scales and details can be achieved by adjusting the camera's viewing angle and resolution, or by changing the position and type of the sensors. These refined operations allow the testing method to adapt to more diverse research needs while maintaining its core advantages, promoting in-depth exploration and technological innovation in the field of battery safety.

[0053] It should be noted that in this application, in step S40, the test method further includes collecting the gases generated during the thermal runaway process of the battery cell under test using a gas composition analyzer. This further encompasses the collection of gases generated during the thermal runaway process of the battery cell under test (S40). This step allows for a comprehensive analysis of the chemical nature of the thermal runaway reaction. Precise analysis of the gas composition reveals details of the chemical reactions occurring during thermal runaway, such as electrolyte decomposition products and organic material pyrolysis products. It not only enriches the dimensions of the test data but also provides direct evidence for assessing the safety of battery cell thermal runaway and studying the thermal runaway mechanism. This comprehensive data acquisition method, combined with changes in physical parameters such as temperature and pressure, can more completely depict the development process of thermal runaway events, providing a scientific basis for improving battery cell design and optimizing battery pack-level thermal management strategies. Of course, in other embodiments not shown, the devices for collecting gas components can be diverse. As long as they meet the requirements of high precision and real-time response, they can adapt to the needs of different test scenarios, ensuring the accuracy and reliability of the data. In these scenarios, the selection and configuration of the gas composition analyzer becomes one of the key factors in improving the scientific validity and practicality of the test method. Through rational layout and precise control, a multi-faceted and in-depth understanding of thermal runaway phenomena can be achieved, promoting improvements in battery technology safety. In other embodiments not shown in the figure, the device for collecting gas components can be integrated into the test chamber and connected to external analytical instruments via pipelines. This ensures both the purity of the gas sample and enhances the overall integrity of the test system. Simultaneously, the gas pressure within the test chamber can be monitored to prevent excessive accumulation and potential safety hazards, ensuring the safety of the entire testing process. This design reflects the thoroughness and forward-thinking nature of the safety considerations in this testing method, creating favorable conditions for subsequent experimental operations and data analysis. Furthermore, various analytical techniques, such as mass spectrometry and chromatography, can be considered in step S40 to more comprehensively and deeply explore the chemical mechanisms of thermal runaway, further highlighting the flexibility and wide applicability of the method. In specific implementation, appropriate gas collection and analysis strategies should be rationally selected based on the cell type, testing purpose, and experimental conditions to achieve the best testing results. In summary, step S40 of this application, by introducing a gas composition analyzer, deepens the understanding of battery thermal runaway phenomena and provides a solid foundation for the modification of cell materials and the design of battery management systems. In other embodiments not shown in the figures, thermal runaway can be triggered and gas collection can be performed simultaneously in different ways. This variation not only expands the application scope of the method but also enhances its adaptability and robustness under different test conditions.

[0054] In implementing the battery thermal runaway testing method of this application, the first step is the preparation of the test sample. Specific steps include precisely placing a miniature heating element, typically a thin-film heater or heating wire, at a predetermined trigger position inside the battery cell under test, such as the root of the tab, the center of the core, or the edge of the electrode sheet. The leads of the heating element are then led out of the battery cell to ensure a stable electrical connection with the programmable power supply. Additional encapsulation is performed at the lead-out location to maintain the structural integrity and electrical isolation of the battery cell, preventing external interference or accidental short circuits. Next, a temperature sensor is placed at a predetermined temperature measurement location on the battery cell, covering the heating element, the positive and negative electrodes, the explosion-proof valve, and the large diagonal area of ​​the battery cell, to acquire temperature change data during thermal runaway. A pressure sensor is placed on the relatively large surface of the battery cell to record the rate of pressure increase. The test sample is placed in a sealed test chamber with pressure resistance and pressure relief capabilities to ensure the safety of the testing process.

[0055] Subsequently, the programmable power supply, through precise programmable control, applies a preset electrical power to the heating element, gradually raising its temperature to the specific temperature range required to trigger thermal runaway, typically between 200°C and 300°C. During heating and thermal runaway, the data acquisition system continuously records readings from temperature and pressure sensors, as well as the real-time voltage and current of the battery cell. This data is crucial for analyzing key parameters of thermal runaway. Furthermore, a high-speed camera captures real-time images of the battery cell's ejection behavior, while a gas composition analyzer collects and analyzes the gases released during thermal runaway, further deepening our understanding of the thermal runaway mechanism.

[0056] After the test, by comparing and analyzing the initial parameters of the battery cell with the real-time data during the thermal runaway process, key parameters of thermal runaway in the tested battery cell can be extracted, such as trigger temperature, maximum temperature, temperature rise rate, pressure peak, voltage drop time, and thermal runaway propagation speed. The entire test process strictly follows preset conditions, ensuring the accuracy and repeatability of the test results and providing a solid data foundation for the optimization of battery safety design and thermal management strategies. In other potential embodiments, the position of the heating element, heating parameters, and sensor layout can be adjusted according to specific needs to adapt to the testing of different types of battery cells, demonstrating the flexibility and wide applicability of this method. Overall, the test method of this application, by triggering thermal runaway through a built-in heating element and supplemented by multi-faceted data monitoring, constitutes a systematic and controllable thermal runaway test platform, promoting technological innovation and progress in the field of battery safety.

[0057] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0058] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0059] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0060] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0061] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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 test method for thermal runaway of a battery cell, characterized in that, Includes the following steps: Step S10: Embed a heating element at a preset trigger position of the battery cell to be tested. The preset trigger position is selected from the root of the tab, the center of the core, or the edge of the electrode sheet. Step S20: A temperature sensor is arranged at a preset temperature measurement position on the battery cell to be tested, and a pressure sensor is arranged on the outer surface of the battery cell to be tested, so as to complete the preparation of the test sample. Step S30: Lead the heating element out of the battery cell under test and connect it to a programmable power supply, so that the programmable power supply applies controllable electrical power to make the heating element generate a temperature gradient in a local area of ​​the battery cell under test that is sufficient to induce thermal runaway, so as to simulate the thermal runaway process of the battery cell under test caused by its internal heat source.

2. The test method according to claim 1, characterized in that, In step S30, the programmable power supply controls the heating power, heating duration, and heating curve of the heating element, wherein the heating curve includes stepped heating, constant power heating, or pulse heating.

3. The test method according to claim 1, characterized in that, After step S10 and before step S20, the test method further includes: Step S11: The lead wire is encapsulated at the lead-out position of the cell under test.

4. The test method according to claim 1, characterized in that, The preset temperature measurement locations include at least the heating element inside the battery cell under test, the positive and negative terminals of the battery cell under test, the explosion-proof valve of the battery cell under test, and the two oppositely arranged large surfaces of the battery cell under test; and / or, The pressure sensor is located on two large surfaces of the battery cell under test, which are positioned opposite each other.

5. The test method according to claim 1, characterized in that, Before the battery cell under test causes thermal runaway, the battery cell under test is placed in a sealed, pressure-resistant test chamber with pressure relief function.

6. The test method according to claim 1, characterized in that, Following step S30, the test method further includes: Step S40: During the temperature rise of the heating element and the thermal runaway of the battery cell under test, the data acquisition system continuously records the real-time temperature value obtained by the temperature sensor, the real-time pressure value obtained by the pressure sensor, and simultaneously records the real-time voltage value and real-time current value of the battery cell under test. Step S50: Compare and analyze the real-time temperature value, real-time pressure value, real-time voltage value, and real-time current value with the initial parameters of the battery cell under test to obtain the key parameters of thermal runaway of the battery cell under test.

7. The test method according to claim 6, characterized in that, The real-time internal resistance value of the cell under test is obtained based on the real-time voltage value and the real-time current value. In step S50, the acquisition of the initial parameters of the battery cell under test includes the data acquisition system recording the initial voltage, initial internal resistance, and initial temperature of the battery cell under test before the programmable power supply powers the heating element. The initial voltage is compared with the real-time voltage value, the initial internal resistance is compared with the real-time internal resistance value, and the initial temperature is compared with the real-time temperature value.

8. The test method according to claim 6, characterized in that, The key parameters for thermal runaway of the battery cell under test include at least the thermal runaway trigger temperature, the maximum thermal runaway temperature, the temperature rise rate, the pressure rise rate, the voltage drop time, and the thermal runaway propagation speed.

9. The test method according to claim 8, characterized in that, The thermal runaway trigger temperature ranges from 200℃ to 300℃.

10. The test method according to claim 6, characterized in that, In step S40, the test method further includes: The flame, smoke, and debris ejection information during the thermal runaway process of the battery cell under test is recorded using a high-speed camera.

11. The test method according to claim 6, characterized in that, In step S40, the test method further includes: The gas generated during the thermal runaway of the battery cell under test was collected using a gas composition analyzer.

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