Lithium battery multi-physical field test equipment and lithium battery multi-physical field test method

Abstract

The present application relates to lithium battery detection technical field, especially to a kind of lithium battery multi-physical field test equipment and lithium battery multi-physical field test method.The lithium battery multi-physical field test equipment of the present application includes: main body, internally provided with chamber, the bearing table is provided in the chamber, the bearing table is used to fix the sample to be detected;Needle extrusion device, with the main body is connected, the needle extrusion device includes drive mechanism and actuating mechanism, the drive mechanism is connected with the actuating mechanism, the actuating mechanism end is provided with needle head or extrusion head, the needle head is internally provided with several embedded thermocouples;Control cabinet, including needle extrusion control device and data acquisition device, the needle extrusion control device is electrically connected with the needle extrusion device, the data acquisition device is electrically connected with the positive pole and negative pole of the sample to be measured respectively.The present application can improve the monitoring capability of lithium battery test.

Description

Technical Field

[0001] This invention relates to the field of lithium battery testing technology, and in particular to a multi-physics field testing device and method for lithium batteries. Background Technology

[0002] With the widespread application of lithium-ion batteries in new energy vehicles, energy storage systems, and other fields, their safety has become a core challenge restricting the industry's development. Thermal runaway, as the most serious safety failure mode of battery systems, has complex causes and its evolution process involves multi-physics coupling characteristics. Current industry-standard single-cell safety testing methods (such as mechanical abuse tests like extrusion and nail penetration) have significant limitations: traditional testing machines can only acquire macroscopic deformation data under single mechanical stress, lacking the ability to simultaneously monitor key parameters such as the dynamic response of battery internal resistance, local heat accumulation distribution, and gas composition evolution. Furthermore, due to the fragmentation of testing methods, existing technologies struggle to construct a complete failure correlation model encompassing mechanical damage, electrothermal characteristics, and chemical decomposition, resulting in insufficient basis for setting safety warning thresholds and a lack of accurate data support for battery system protection design. Currently, lithium-ion battery nail penetration testing machines can only collect external temperature data of the battery by connecting external thermocouples, and cannot monitor the internal temperature changes of the battery in real time. Summary of the Invention

[0003] In view of this, embodiments of the present invention provide a multi-physics field testing device for lithium batteries and a control method thereof, in order to solve the technical problem of poor monitoring capability of key parameters in existing lithium-ion battery testing technologies.

[0004] In a first aspect, the present invention provides a multi-physics field testing device for lithium batteries, comprising: The main body has an internal chamber, and a support platform is provided in the chamber for fixing the sample to be tested; A needle-punching and extrusion device is connected to the main body. The needle-punching and extrusion device includes a driving mechanism and an execution mechanism. The driving mechanism is connected to the execution mechanism in a transmission manner. The execution mechanism is provided with a needle-punching head or an extrusion head at its end. The needle-punching head is provided with a plurality of embedded thermocouples inside. The control cabinet includes a needle-punching and squeezing control device and a data acquisition device. The needle-punching and squeezing control device is electrically connected to the needle-punching and squeezing device, and the data acquisition device is electrically connected to the positive and negative terminals of the sample to be tested, respectively.

[0005] Preferably, the needle head has a hollow structure.

[0006] Preferably, several external thermocouples are installed around the support platform.

[0007] Preferably, the plurality of external thermocouples include first thermocouples distributed along a first direction and second thermocouples distributed along a second direction, with six first thermocouples distributed in a regular hexagonal pattern forming a first thermocouple group and six second thermocouples distributed in a regular hexagonal pattern forming a second thermocouple group.

[0008] Preferably, it also includes an infrared camera, which is mounted on the main body and electrically connected to the data acquisition device.

[0009] Preferably, it also includes a high-definition camera, which is mounted on the main body and electrically connected to the data acquisition device.

[0010] Preferably, the chamber also includes a gas pipeline that connects the inside and outside of the chamber, and a valve is provided on the gas pipeline for controlling the opening and closing of the gas pipeline.

[0011] Preferably, the main body is also provided with a gas collection port, which is used to collect the gas generated during the detection process.

[0012] In a second aspect, the present invention provides a multi-physics field testing method for lithium batteries, which utilizes the multi-physics field testing equipment for lithium batteries described in the first aspect for testing, the method comprising: Obtain the needle prick test parameters and / or compression test parameters; The needle head is controlled to puncture the test piece according to the needle puncture test parameters and / or the extrusion head is controlled to extrude the test piece according to the extrusion test parameters; Collect test data, which includes at least the internal temperature of the test piece, the ambient temperature of the test piece, the voltage during the test time, and the internal resistance of the test piece. Multiphysics analysis was performed on the failure process of the test piece based on the test data.

[0013] Preferably, the acquired test data includes at least the internal temperature of the test piece, the ambient temperature of the test piece, the voltage of the test piece, and the internal resistance of the test piece. The voltage and internal resistance of the test piece are obtained using a voltage and internal resistance acquisition line. During the process of the needle penetrating the test piece, the temperature at different depths inside the test piece is detected by the built-in thermocouple. The temperature distribution around the test specimen is detected using an external thermocouple. The gas generated by the battery during thermal runaway combustion and explosion of the test piece is collected using a gas collection port; Use high-definition cameras to acquire real-time images of thermal runaway; Infrared cameras are used to acquire infrared images of the heat distribution of the test specimen before thermal runaway combustion and explosion.

[0014] In summary, the beneficial effects of the present invention are as follows: The lithium battery multiphysics testing equipment and method provided by this invention incorporates multiple embedded thermocouples within the puncture head, allowing direct contact with the internal heat source of the battery cell without external attachment. This significantly improves the response speed and spatial resolution of temperature acquisition, enabling precise capture of the local temperature gradient evolution process from force-induced puncture to thermal runaway. This is crucial for identifying the initiation location and development trend of hotspots, while reducing measurement errors due to poor contact or thermal hysteresis between the thermocouples and the battery. Electrical connections to the positive and negative electrodes of the sample allow the equipment to monitor changes in battery internal resistance and voltage in real time during the same test. Combining multi-point temperature data reveals the temporal relationship between temperature abrupt changes and electrical performance degradation, helping engineers quantify the immediate impact of mechanical damage on electrochemical performance. This invention, through the simultaneous acquisition of key parameters of multiphysics indicators, fills the gap in existing technologies that can only acquire external temperature and single mechanical data, providing comprehensive and accurate data support for the protection design of lithium battery systems. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, and these are all within the protection scope of the present invention.

[0016] Figure 1 This is an overall structural block diagram of the lithium battery multi-physics field testing device of the present invention.

[0017] Figure 2 This is a schematic diagram of the main body of the lithium battery multiphysics field testing equipment in this invention.

[0018] Figure 3 This is a schematic diagram of the arrangement structure of the external thermocouple in the lithium battery multiphysics field testing equipment of the present invention.

[0019] Figure 4 This is a three-dimensional structural diagram of the back of the multi-physics field testing device for adjusting lithium batteries according to the present invention.

[0020] Figure 5 This is a flowchart illustrating the multi-physics field testing method for lithium batteries according to the present invention.

[0021] Figure 6 This is a flowchart illustrating the data acquisition method of the present invention.

[0022] The components and their numbers shown in the picture: 1. Main body, 11. Chamber, 12. Support platform, 131. First thermocouple, 132. Second thermocouple, 2. Needle punching and extrusion device, 21. Drive mechanism, 3. Control cabinet, 4. Infrared camera, 5. High-definition camera, 6. Gas pipeline, 61. Valve, 7. Specimen. Detailed Implementation

[0023] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0024] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0025] It should be noted that all actions involving the acquisition of signals, information, or data in this invention are carried out in compliance with the relevant data protection laws and regulations of the locality and with authorization from the owner of the relevant device.

[0026] Example 1 Please see Figure 1 This embodiment provides a multi-physics field testing device for lithium batteries, including a main body 1, a needle-punching and extrusion device 2, and a control cabinet 3.

[0027] like Figure 2 As shown, the main body 1 has a chamber 11 inside, and a support platform 12 is provided in the chamber 11. The support platform 12 is used to fix the sample to be tested. The support platform 12 is used to accurately fix the battery sample to be tested and ensure that the force direction and position are consistent to avoid clamping deviation. The needle-punching and extrusion device 2 is connected to the main body 1. The needle-punching and extrusion device 2 includes a drive mechanism 21 and an execution mechanism. The drive mechanism 21 is connected to the execution mechanism in a transmission manner. The execution mechanism is provided with a needle-punching head or an extrusion head at its end. The needle-punching head is provided with a plurality of embedded thermocouples inside. The embedded thermocouple extends directly into the battery cell, collecting multi-point temperature data in real time while piercing or squeezing the battery. This enables high-response speed and high spatial resolution monitoring of the internal heat distribution of the battery cell, overcoming the limitation of traditional methods that can only measure external temperature. The control cabinet 3 includes a needle-punching and squeezing control device and a data acquisition device. The needle-punching and squeezing control device is electrically connected to the needle-punching and squeezing device 2, and the data acquisition device is electrically connected to the positive and negative terminals of the sample to be tested, respectively.

[0028] The needle-punch control device in control cabinet 3 is responsible for driving motion precision and mechanical parameter control. The data acquisition device is electrically connected to the positive and negative terminals of the battery and can simultaneously acquire battery voltage, current, and internal resistance change signals. By simultaneously acquiring mechanical, thermal, and electrochemical parameters during the test, this equipment can reveal the characteristics of heat accumulation and electrical performance degradation of the battery during needle-punch or compression, providing reliable multi-physics experimental data support for accurately setting thermal runaway warning thresholds and optimizing battery safety design.

[0029] This embodiment can also design the needle head at the end of the actuator as a hollow structure, that is, to form a continuous hollow channel inside the needle head for embedding multiple thermocouples and leads. This ensures the overall mechanical strength of the needle head, enabling it to withstand the mechanical load required to puncture the battery, while also providing space for the temperature sensor to be close to the internal heat source of the battery cell. This significantly improves the response speed and spatial resolution of internal temperature acquisition, solving the problems of traditional solid needle heads being unable to accommodate sensing elements or easily causing wire pulling damage. The hollow structure refers to removing the core part from the needle head material, retaining the outer wall to form a shell, thus accommodating the two key functions of sensing wiring and mechanical support.

[0030] like Figure 3As shown, this embodiment also arranges several external thermocouples around the support platform 12 inside the chamber 11. These thermocouples are fixed to the periphery of the support platform 12 and close to the sample shell to collect temperature signals at different locations on the external surface of the battery. Unlike the thermocouples embedded in the needle probe, which mainly monitor the internal thermal evolution of the battery cell, the external thermocouples can reflect the heat distribution and heat dissipation on the outside of the battery in real time. The comparison of the two data can reveal the timing and intensity of internal heat accumulation and outward conduction. By simultaneously acquiring the internal and external temperatures at multiple points, multi-dimensional temperature monitoring of the entire process of battery thermal runaway is achieved, which not only fills the blind spots of relying solely on internal or external temperature measurement, but also improves the accuracy of thermal management models and early warning threshold settings. External thermocouples refer to temperature sensors that are directly installed on or near the surface of the sample to measure surface temperature. Together with the built-in thermocouples, they form a multi-level temperature monitoring system, solving the problems of slow response and low spatial resolution of traditional single temperature measurement methods.

[0031] In this embodiment, the plurality of external thermocouples include first thermocouples 131 distributed along a first direction and second thermocouples 132 distributed along a second direction. Every six first thermocouples 131 distributed in a regular hexagonal shape form a first thermocouple 131 group, and every six second thermocouples 132 distributed in a regular hexagonal shape form a second thermocouple 132 group.

[0032] In this embodiment, two types of external thermocouples are arranged around the support platform 12: one type is evenly distributed along a first direction, and the other type is distributed along a second direction perpendicular to it. Every six thermocouples are arranged according to the vertex positions of an equilateral hexagon to form a thermocouple group. The group consisting of six first thermocouples 131 is called the first thermocouple group 131, and the group consisting of six second thermocouples 132 is called the second thermocouple group 132. The regular hexagonal distribution means that the six thermocouples in each group are arranged on the plane with the same radius and interval along the circumference at equal angles, forming a perfectly symmetrical hexagonal structure. This arrangement can collect the temperature of the battery shell surface 360° in two orthogonal directions, which not only ensures the monitoring of the temperature gradient along a single direction, but also captures the oblique heat flow distribution through complementary opposite groups, achieving higher spatial resolution and more comprehensive thermal field coverage, and solving the problem of monitoring blind spots that are easy to occur in traditional unidirectional or point temperature measurement.

[0033] like Figure 4As shown, this embodiment also adds an infrared camera 4 to the main body 1 of the device and electrically connects it to the data acquisition device, thereby enabling the synchronous acquisition of infrared thermal imaging data of the battery's exterior during the needle penetration or compression test. The infrared camera 4 receives the infrared radiation emitted from the battery surface and converts it into a temperature distribution map, enabling real-time monitoring of the two-dimensional temperature field of the entire battery surface. This complements the discrete measurement point data obtained by the internal and external thermocouples, visually presenting the location and diffusion trend of hot spots, which helps identify abnormal temperature rise areas and verify the accuracy of thermocouple data. This structure solves the problem that relying solely on point sensors to measure temperature makes it difficult to grasp the overall thermal field distribution, improving the spatial resolution and early warning reliability of multi-physics field testing. Here, "infrared camera 4" refers to a thermal imaging device capable of acquiring information in the infrared band beyond visible light and generating temperature images.

[0034] like Figure 4 As shown, in this embodiment, an additional high-definition camera 5 is installed on the main body 1 of the device and electrically connected to the data acquisition device to capture the dynamic rupture, crack propagation, exhaust emission and visible light changes before thermal runaway of the battery during mechanical abuse such as needle puncture or squeezing.

[0035] This embodiment adds a gas pipeline 6 and its valve 61 to the existing equipment, connecting the inside and outside of chamber 11. The gas pipeline 6 can be connected to an external gas source or exhaust port. Through this channel, the atmosphere inside chamber 11 can be replaced or discharged, and the valve 61 controls its opening and closing. When the battery releases flammable or toxic gases during puncture or compression, the valve 61 can be opened in time to ventilate or blow in inert gas, preventing gas accumulation and potential safety hazards. A constant pressure environment inside chamber 11 can be maintained by adjusting the airflow rate of the pipeline. This solution solves the problems of temperature measurement interference and safety risks caused by gas accumulation during testing. The gas pipeline 6 refers to a closed pipeline system used to transport or discharge gas, and the valve 61 refers to a mechanical or electrical control device used to precisely control the opening and closing of the pipeline.

[0036] This embodiment also adds a gas collection port to the main body 1 of the device. This collection port is a dedicated vent hole opened on the wall of the chamber 11. It can be connected to external devices such as a gas collection bag or a gas analyzer through a pipeline to collect flammable or decomposition gases generated by the battery during the needle puncture or compression process in real time. The setting of the gas collection port can prevent harmful gases from directly diffusing into the environment, reduce the safety risks at the test site, and provide accurate samples for subsequent gas composition analysis and concentration monitoring, solving the problems of untimely and incomplete gas sampling in traditional tests.

[0037] Example 2 like Figure 5As shown, this embodiment provides a multiphysics testing method for lithium batteries, characterized in that the testing is performed using a multiphysics testing device for lithium batteries as described in Embodiment 1, and the method includes: S1: Obtain needle puncture test parameters and / or compression test parameters; The needle penetration test parameters include the force, speed, and position of the needle penetration, while the compression test parameters include the compression force, rate, and contact surface shape. This step sets and sends the above parameters to the drive mechanism through the control cabinet to achieve controllable and repeatable needle penetration or compression actions, thereby ensuring the consistency of test conditions and improving data comparability.

[0038] S2: Control the needle head to puncture the test piece according to the needle puncture test parameters and / or control the extrusion head to extrude the test piece according to the extrusion test parameters; The needle head is a pointed actuator used to penetrate the battery cell, and the extrusion head is an actuator used to apply compressive load. In this step, the driving mechanism drives the needle head or extrusion head to puncture or extrude the sample according to the parameters obtained in S1, so as to controllably reproduce the battery failure scenario and evaluate mechanical robustness.

[0039] S3: Collect test data, which includes at least the internal temperature of the test piece, the ambient temperature of the test piece, the voltage during the test time, and the internal resistance of the test piece. The internal temperature is measured by an embedded thermocouple, while the ambient temperature is measured by an external thermocouple or an infrared camera. The voltage refers to the positive and negative electrode voltage values, and the internal resistance is the electrochemical impedance or DC resistance. In this step, the above multi-physics data are collected in real time by each sensing system during the test to comprehensively reveal the correlation between heat accumulation and electrical performance evolution under mechanical force and to improve the depth of analysis.

[0040] S4: Perform multiphysics analysis on the failure process of the test piece based on the test data.

[0041] Multiphysics analysis refers to the integrated interpretation of mechanical load, thermal field evolution, and electrochemical response. This step uses data analysis software to perform fusion statistics and visualization processing on the collected data in order to analyze the battery failure mechanism and extract key early warning indicators, providing reliable data support for accurately setting thermal runaway early warning thresholds and optimizing safety design.

[0042] like Figure 6 As shown, in this embodiment, step S3: collecting test data, the test data includes at least the internal temperature of the test piece, the ambient temperature of the test piece, the voltage of the test piece, and the internal resistance of the test piece, including: S31: Use the voltage and internal resistance acquisition line to obtain the voltage and internal resistance of the test piece under test; This step utilizes a voltage and internal resistance acquisition line to measure the positive and negative electrode voltages and internal resistance of the battery in real time. This ensures that changes in electrochemical performance are acquired synchronously during the puncture / squeeze process. The measurement is performed by connecting one end to the positive electrode and the other end to the negative electrode. This method can accurately reflect the battery's internal impedance and voltage dynamics, providing reliable electrical parameter support for subsequent thermal, electrical, and mechanical data correlation analysis and improving the accuracy of fault early warning.

[0043] S32: During the process of the needle penetrating the test piece, the temperature at different depths inside the test piece is detected by the built-in thermocouple. During the needle insertion process, the built-in thermocouple continuously collects the internal temperature of the battery cell at different depths to accurately capture the starting position of the heat source and the evolution of the temperature gradient. This solution achieves high-resolution temperature measurement by directly attaching the thermocouple to the battery cell, which can significantly improve the internal temperature response speed, help identify early hot spots and optimize thermal management strategies.

[0044] S33: Use an external thermocouple to detect the temperature distribution around the test piece; This step utilizes external thermocouples to measure the surface temperature distribution around the sample in order to obtain information on the thermal gradient of the battery casing. By fixing the thermocouples around the perimeter of the support stage and making them in close contact with the sample, the heat dissipation can be comprehensively monitored, supplementing the blind spots in internal temperature measurement and providing empirical data for evaluating the thermal runaway propagation path.

[0045] S34: Collect the gas generated by the battery during thermal runaway combustion and explosion of the test piece using the gas collection port; This step involves timely collection of gases generated by thermal runaway combustion or explosion through a gas collection port to prevent the leakage of harmful gases and to provide samples for component analysis. This scheme achieves closed sampling through the linkage of pipelines and valves, which can obtain information on gas properties while ensuring safety, and provide key evidence for assessing the degree of hazard of thermal runaway.

[0046] S35: Uses a high-definition camera to acquire real-time images during thermal runaway; This step utilizes a high-definition camera to capture the transient thermal runaway process at a high frame rate, visually recording rapid mechanisms such as crack propagation and exhaust emission. Recording is triggered synchronously by a high-definition camera mounted on the main body, capturing millisecond-level dynamic images and providing visual evidence for analyzing failure mechanisms and assessing structural reliability.

[0047] S36: Use an infrared camera to acquire infrared images of the heat distribution of the test piece before thermal runaway combustion and explosion.

[0048] This step utilizes an infrared camera to acquire infrared thermal images of the battery surface before thermal runaway combustion or explosion, visually presenting the location and diffusion trend of hot spots. By detecting infrared radiation on the battery surface to generate a temperature field map, thermocouple measuring points can be supplemented, improving the overall spatial resolution and providing intuitive data support for accurately setting early warning thresholds and optimizing safety design.

[0049] In this embodiment, step S32: during the process of the needle penetrating the test piece, detecting the temperature at different depths within the test piece using a built-in thermocouple includes: S321: Based on the preset detection target, determine the detection depth of multiple targets and the initial step size and initial dwell time of the propulsion control to obtain the preset control parameters; The preset detection target refers to the ultimate purpose or goal of the test, such as detecting the thermal runaway characteristics of the battery, the temperature response at a preset location, etc., to determine the required depth range and test requirements. The preset location can be the outer layer area of ​​the battery, the battery cell area, the center area of ​​the battery, etc.

[0050] Target detection depth refers to the depth at which temperature detection is expected to be performed during testing. These depths can be set according to the battery's physical structure and experimental requirements, typically involving different layers within the battery.

[0051] For example, lithium batteries typically consist of a multi-layered structure, including the casing, battery cell, separator, and electrodes. The internal structure may vary depending on the battery design. Therefore, based on the battery's physical structure, several key depth regions can be identified first, such as: Battery outer layer depth, which is the outermost temperature monitoring layer, is mainly used to assess temperature changes and heat transfer on the outside of the battery.

[0052] The battery cell area is where thermal runaway is most likely to occur, so it is necessary to focus on temperature monitoring in this area.

[0053] The temperature changes more slowly in the central region of the battery, but it still needs to be monitored to assess the possibility of heat buildup.

[0054] If the goal of the test is to assess the risk of thermal runaway, the following target depths are selected for testing: Target Depth 1: Used to monitor temperature changes in the battery casing area and assess the impact of external heat transfer on the interior.

[0055] Target Depth 2: This depth region is particularly important for thermal runaway and is mainly used to monitor temperature changes inside the battery.

[0056] Target Depth 3: In the central region of the battery, although heat conduction is slower, temperature changes in the central region may reveal early signs of thermal runaway.

[0057] In addition to battery structure, we can also determine the target depth based on historical experimental data of the battery. For example, if experimental data shows that thermal runaway usually occurs at a specific depth, or if temperature monitoring reveals a significant temperature rise at a specific depth, then we can select the depth that needs to be monitored in detail based on this data.

[0058] The initial step size of the propulsion control indicates the initial propulsion interval during the spike propulsion process. The step size setting determines the spatial resolution of the test, based on the testing requirements.

[0059] The initial dwell time pointer indicates the initial time the probe stays at each target detection depth position to ensure that sufficient temperature data is collected.

[0060] Before starting the test, the researchers determined different detection depths based on the experimental objectives and set the step size of the needle penetration and the sampling time at each stop point, which served as preset control parameters. The selection of these control parameters typically depends on the required resolution and testing accuracy. The purpose of setting these parameters is to ensure that the test can cover all necessary depths and that sufficient temperature data can be obtained at each depth point.

[0061] S322: According to the preset control parameters, control the needle head to advance to the current stopping position and perform stopping sampling to obtain the temperature sequence of the current stopping position and its corresponding depth information; Dwell sampling involves holding the pointer probe at each target location for a specific time and collecting temperature data at that location. The duration and location of the dwell sampling are determined by preset control parameters.

[0062] A temperature sequence is a sequence of temperature data measured by the needle during the dwell period. It typically includes a timestamp and temperature value for subsequent analysis.

[0063] This step, based on previously set control parameters, propels the needle probe to the currently predetermined target depth and pauses to collect temperature data at that location. This temperature data provides detailed information about temperature changes at that depth, supporting subsequent analysis. After reaching the target depth, the needle probe pauses at its current position and collects temperature data. This temperature data is transmitted to the control system in real time, forming a temperature sequence and storing it. Simultaneously, the needle probe's current position and temperature data are tagged with corresponding depth information for later analysis. This embodiment ensures accurate temperature data at each target depth point, resulting in more comprehensive experimental data. By collecting temperature sequences at different depths, researchers can accurately understand the internal temperature distribution of the battery, providing reliable data support for the assessment and analysis of thermal runaway.

[0064] S333: If the current position is the first position, record the temperature sequence of the current position as the baseline temperature data; The initial stop position refers to the location where the needle tip first stops during the needle penetration test, i.e., the first sampling point at the start of the test. The baseline temperature data refers to the temperature data collected at the initial stop position, serving as the benchmark for all subsequent data analysis. When the needle tip first stops, the control system records the temperature data at that location and saves it as the baseline temperature data. This data will be used as a reference for subsequent analysis to determine the trend and magnitude of temperature changes at other locations.

[0065] S334: If the current stopping position is not the first stopping position, then according to the temperature sequence and the temperature sequence corresponding to the previous stopping position in the same needle puncture test, the temperature change amplitude between adjacent stopping positions is obtained to obtain the first change feature; Non-initial stop positions refer to any subsequent stop positions during the needle prick test, other than the initial stop position. A temperature sequence refers to continuous temperature data collected at a specific stop position, typically plotted with time on the x-axis and temperature on the y-axis, recording the temperature change at that position over time. The first characteristic of change refers to the temperature change between adjacent stop positions; comparing the temperature difference between two stop positions reflects the spatial distribution and propagation characteristics of heat.

[0066] After each needle tip advances to a new target location, the temperature data at that location is recorded and compared with the temperature data at the previous location. The temperature change amplitude is obtained by calculating the temperature difference between two adjacent locations. A large temperature difference indicates drastic temperature changes and potential localized heat accumulation; a small temperature difference indicates uniform temperature changes and relatively stable heat diffusion. These initial characteristics will be used to subsequently assess the trend of temperature changes and the risk of thermal runaway.

[0067] S335: Based on the changes in the temperature sequence within a preset observation time window, obtain the temperature change rate to obtain the second change feature; The rate of temperature change refers to the rate at which temperature changes over time, usually expressed as the ratio of the temperature change to the time interval. For example, the rate of temperature increase can be calculated by the change in temperature per unit time. The second characteristic of change refers to time-dependent features such as the rate of temperature change; analyzing the trend of temperature change within a certain time window helps identify phenomena such as thermal runaway.

[0068] At each observation location, temperature data is recorded, and the rate of temperature change at that location within a preset observation time window is calculated. This time window may be a preset fixed duration used to measure the rate of temperature change over a certain period. The rate of temperature change can be calculated as the ratio of the temperature difference to the time difference to obtain the rate of temperature change at each observation location.

[0069] This step provides dynamic information on temperature changes, allowing us to determine if there is a sharp increase in temperature and thus identify potential risks of thermal runaway in advance. Temperature change states can be categorized into normal, warning, and abnormal states.

[0070] S336: Determine the temperature change state based on the first and second change characteristics to obtain the temperature change state; if the spatial change is large and the temperature rise rate is fast, it is determined to be an abnormal state, indicating that the battery has a risk of thermal runaway. If the spatial change is small and the temperature rise rate is slow, it is determined to be a normal state, indicating that the battery temperature change is within the normal range. If the temperature change is at a critical state, it is determined to be a warning state, requiring additional monitoring measures. The critical state includes: the battery temperature rise is close to the threshold of thermal runaway, for example, the temperature rise rate reaches or exceeds the normal safe temperature rise rate, but has not yet reached the critical temperature required for thermal runaway; the temperature rise rate (temperature change rate) is close to the maximum safe temperature rise rate set in the experiment, but has not completely exceeded the range. In this state, although the temperature has not yet reached the safety limit, there is a potential for rapid temperature rise, so monitoring needs to be strengthened; the temperature rate is close to the preset warning rate, but has not exceeded it; the temperature change rate is close to the maximum set value, that is, the temperature rise rate has reached the preset critical warning rate; the temperature change amplitude exceeds a certain value, but has not reached complete loss of control, for example, the temperature difference between two adjacent positions reaches the preset threshold; the heat distribution is uneven, that is, the first change characteristic shows that there are local hot spots, although the overall temperature has not reached the danger zone, there is a risk of local overheating.

[0071] S337: Switch the needle advance step size or switch the dwell time according to the temperature change state to update the advance control parameters and control the needle head to advance and sample at the next dwell position.

[0072] The advance step size is the distance the pointer spike advances during its advancement. The size of the step size determines the progress of each advance. The dwell time is the duration the pointer spike remains at each dwell position, determining the duration of temperature sampling.

[0073] This step, based on the preceding assessment of temperature changes, dynamically adjusts the advancement step size and dwell time during the needle penetration process. By adjusting the advancement strategy in a timely manner according to the battery's temperature changes, the experiment can flexibly respond to different temperature variations, thereby optimizing the testing process.

[0074] If the temperature change is abnormal or in a warning state, reduce the advance step size or increase the dwell time to improve the accuracy of temperature data acquisition. If the temperature change is normal, maintain the current advance step size and dwell time, and proceed with the test according to the predetermined schedule.

[0075] This step allows for adjustments to the propulsion strategy based on real-time temperature changes, making the testing process more flexible and precise. This adjustment effectively avoids incomplete or biased data acquisition due to drastic or uneven temperature fluctuations, thereby improving the accuracy and reliability of experimental results.

[0076] In the needle penetration abuse test, the change in internal temperature of the battery often exhibits strong nonlinearity: in some stages the temperature rises slowly; in other stages the temperature rise rate increases sharply or the abrupt change point drifts, making it easy to miss the key thermal accumulation evolution process, resulting in insufficient internal temperature profile resolution or unstable equivalent detection effect corresponding to the preset detection depth.

[0077] This embodiment utilizes a built-in thermocouple to monitor temperature changes at different depths inside the battery in real time during the needle penetration test. The temperature change trend of the embedded thermocouple is used as a feedback signal to adaptively adjust the needle penetration method. When the temperature rise is gradual, the advancement is accelerated or the step size is increased. When the temperature rise is drastic, the step size is reduced and the dwell time is increased, thereby improving the spatial and temporal sampling density in key stages and maintaining the overall efficiency of the test.

[0078] S32: During the process of the needle penetrating the test piece, the temperature at different depths within the test piece is detected using the built-in thermocouple, including: S3201: Obtain at least one preset detection depth, and set the initial step size and initial dwell time of the propulsion control according to the preset detection target to obtain preset control parameters; The preset detection depth refers to the target depth set before the test begins, based on experimental requirements. This can be a specific location inside the battery to acquire temperature data at that location. Before the test begins, the depth location to be detected is determined. Different depths are set based on the experimental target, and appropriate step sizes and dwell times are selected to ensure accurate acquisition of temperature data at each target depth. The preset control parameters are the depth location, initial step size, and initial dwell time. S3202: According to the preset control parameters, control the needle head to advance to the current stopping position and perform stopping sampling to obtain the temperature sequence of the current stopping position and its corresponding depth information; Dwell sampling involves the needle probe remaining stationary at the target location for a specified time, during which a temperature data sequence is collected at that location. The temperature sequence consists of recorded temperature data points within a defined time window, typically including a timestamp and the temperature value. Depth information refers to the depth data at the current dwell position, used to identify the depth at which the temperature data was collected. Based on set control parameters, the needle probe advances to the target dwell position. Upon reaching the target position, the needle probe remains stationary for a certain period to collect temperature data and record the temperature sequence at that current dwell position. Each temperature data point is accompanied by corresponding depth information, allowing for accurate identification of the depth at which the data corresponds during subsequent analysis.

[0079] S3203: After advancing to the target dwell position corresponding to the preset detection depth, obtain the internal temperature change curve within the dwell time window; The target dwell position is the depth location reached by the pointer spike during its advancement, where temperature sampling is required. The dwell time window is the time interval during which the pointer spike remains at the target dwell position, and the temperature data collected during this period reflects the temperature change process at that location. The internal temperature change curve depicts the temperature change trend by comparing the temperature data collected by the built-in thermocouple with time.

[0080] Once the needle tip reaches the target stopping position, it will remain there and begin sampling. Temperature data will be continuously recorded over time, forming a temperature change curve. This temperature curve can be used to determine characteristics such as the speed and duration of the temperature response, helping to assess the thermal behavior of the battery or the device under test.

[0081] S3204: Consistency judgment is made based on the internal temperature change curve; Consistency assessment refers to comparing the preset temperature response characteristics with the actual temperature change curve to determine whether the test data meets expectations. Temperature response characteristics refer to preset temperature change patterns, including parameters such as the rate of temperature rise, the onset time of temperature rise, and temperature plateau. The internal temperature change curve can be compared with the preset temperature response characteristics. By analyzing features such as the rate of temperature change and the duration of the temperature plateau, it can be determined whether the current temperature change is consistent with the expected temperature response. This consistency assessment helps ensure the depth of testing and the accuracy of temperature data.

[0082] S3205: When the consistency does not meet the preset conditions, compensation and adjustment shall be performed according to the consistency judgment result; Compensation adjustment refers to adjusting control parameters such as test depth and dwell time based on the consistency judgment results to restore the temperature response effect corresponding to the preset detection depth. Compensation adjustments are made based on the consistency judgment results (e.g., the temperature response is too shallow or too deep). For example, if the detection depth is too shallow, it can be compensated for by increasing the propulsion amount; if the temperature response is delayed, the dwell time can be extended. This embodiment avoids data errors caused by changes in the experimental environment through dynamic adjustment. It improves the flexibility of testing, enabling accurate depth correction even if there are changes in equipment or material conditions during the experiment.

[0083] S3206: Based on the compensation adjustment results, execute the compensation action; specifically, based on the compensation adjustment results, execute corresponding actions, such as continuing to advance to a new depth, inserting additional dwell positions, extending the dwell time, etc. Ensure that the temperature data at each detection depth meets the expected response.

[0084] Compensation refers to making up for the inconsistency in temperature response in the preceding steps by controlling the depth of needle insertion, dwell time, or other sampling parameters.

[0085] S3207: Generate a correction depth sequence based on the compensated and adjusted temperature data, and store the corresponding internal temperature data based on the correction depth sequence.

[0086] The calibration depth sequence is an actual detection depth sequence generated based on the compensation adjustment results. It represents the depth equivalent to the preset detection depth under varying conditions of the test piece. After compensation adjustment, corresponding temperature data is generated based on the calibration depth, and this data is stored to ensure that the temperature data at each measurement point accurately matches its detection depth. Through the calibration depth sequence, test data can be systematically stored, facilitating subsequent analysis and data comparison.

[0087] In this embodiment, step S3204: performing consistency judgment based on the internal temperature change curve includes: S32041: Obtain the preset temperature change threshold; The preset temperature change threshold refers to the standard value set before the test begins. It is used to compare and judge whether the temperature change meets expectations. It is a maximum value of the rate or magnitude of temperature change set according to experimental requirements. If the temperature change exceeds the threshold, it is considered abnormal.

[0088] Before the test begins, the experimenter presets a temperature change threshold based on the test objectives. This threshold can be an upper limit on the heating rate, for example, setting the temperature to rise no more than 2°C per minute. The preset temperature change threshold will serve as the benchmark for judging temperature anomalies.

[0089] S32042: Compare the preset temperature change threshold with the current temperature change curve; The current temperature change curve is the relationship between real-time temperature data collected by the built-in thermocouple and time during the test, when the needle tip is at a specified depth. This curve reflects the temperature change over time. At each test pause, the temperature sensor collects data to generate the temperature change curve. The control system compares the real-time temperature change curve with a preset temperature change threshold to determine if there are any abnormal temperature fluctuations. Within each time window, the system acquires the current temperature change and compares it with the preset temperature change threshold (e.g., a maximum heating rate of 1°C / s). If the current temperature curve exceeds this threshold, the temperature response is considered abnormal. The comparison method can be direct numerical comparison; for example, if the temperature increment per second exceeds a set threshold, a consistency judgment failure is automatically triggered.

[0090] S32043: If the current temperature change does not exceed the preset threshold, it is determined that the consistency meets the preset conditions.

[0091] S32044: If the current temperature change exceeds the preset threshold, it is determined that the consistency does not meet the preset conditions, and the test anomaly type is determined according to the internal temperature change curve. The test anomaly type includes at least equivalent depth too shallow, equivalent depth too deep, and temperature response delay.

[0092] S33044: If the current temperature change exceeds a preset threshold, it is determined that the consistency does not meet the preset conditions, and the test anomaly type is determined based on the internal temperature change curve, including: If the rate of temperature increase is lower than the preset minimum rate of increase threshold, the equivalent depth is determined to be too shallow.

[0093] A preset minimum heating rate threshold is set to ensure normal temperature changes. A minimum heating rate is preset; rates below this threshold are considered abnormal temperature responses. The system calculates the current heating rate based on the collected temperature data. The heating rate is calculated by dividing the temperature change within each time window by the duration of that time window.

[0094] If the heating rate is lower than the minimum heating rate threshold, it is considered that the needle tip has not reached the preset depth, resulting in slow temperature change. The system will determine that the equivalent depth is too shallow.

[0095] If the rate of temperature increase exceeds the preset maximum heating rate threshold, the equivalent depth is considered too deep. The preset maximum heating rate threshold is a maximum heating rate set to ensure the temperature change is not too drastic; exceeding this rate is considered an abnormal temperature change. If the temperature rises too quickly, it usually indicates that the needle has penetrated too deeply, causing an excessive temperature response. If the rate of temperature increase exceeds the maximum heating rate threshold, the equivalent depth is considered too deep, meaning the test depth exceeds expectations.

[0096] If the response time of a temperature change exceeds the preset maximum response time threshold at the preset detection depth, it is considered a temperature response delay. The response time of a temperature change refers to the time required from the start of the test until the temperature begins to change significantly. An excessively long response time usually indicates insufficient heat conduction or that the test depth has not reached the expected level.

[0097] Temperature response delay: If the set temperature fails to respond as expected, it may be due to factors such as test depth deviation, uneven heat conduction, or problems with the test equipment. Temperature response time is the time interval from when the needle reaches the preset depth to when the temperature begins to change significantly. By calculating the difference between the starting point of the temperature curve and the preset response time, if this time exceeds a preset threshold, it is considered a temperature response delay.

[0098] In this embodiment, S3205: When the consistency does not meet the preset conditions, compensation adjustment based on the consistency judgment result includes: S32051: Based on the consistency judgment results, determine the type and direction of the acupuncture advancement deviation; The type of deviation refers to whether the abnormality is caused by the needle tip being advanced too shallowly or too deeply, while the direction refers to whether the depth of needle tip advancement needs to be further increased or decreased. When the consistency judgment result shows a deviation in temperature response, the system will determine the deviation type of needle advancement based on the type of temperature change (such as the rate of temperature rise, response time, etc.). For example, if the temperature change is too slow, it may be due to insufficient needle tip advancement depth, resulting in a delayed temperature response; conversely, if the temperature change is too fast, it may be due to excessive needle tip advancement, resulting in an overreaction. S32052: If the equivalent depth is determined to be too shallow, compensation is made by continuing to advance the needle to a new stopping position. Shallow equivalent depth means that during the test, the actual depth of the needle tip advance did not reach the preset target depth, resulting in a delayed temperature response or excessively slow temperature rise. By adjusting control parameters, such as continuing to advance the needle tip or adjusting the stopping position, the depth deviation during the test is corrected to ensure that the test data conforms to the preset depth response characteristics. If the temperature response shows an excessively slow heating rate or an excessively long response time, the control system will automatically determine that the equivalent depth is too shallow, i.e., the needle tip has not penetrated to the predetermined depth. At this time, the system will control the needle tip to continue advancing until the target depth is reached. Insufficient depth will cause a lag in temperature change response; therefore, by continuing to advance the needle tip, the temperature response can be made closer to the preset temperature change characteristics.

[0099] S32053: If the equivalent depth is determined to be too deep, compensation is made by retracting to the acceptable position and performing a stop sampling. An excessively deep equivalent depth means that during the test, the actual depth of the needle tip exceeds the preset target depth, resulting in an excessively rapid temperature response that may no longer represent the true temperature change at the target depth. Retracting to the acceptable position means that when the test depth is too deep, the control system adjusts the needle tip's advance to return to the correct stop position for sampling. When the consistency judgment shows an excessively rapid temperature response, it may be due to the needle tip advancing too deep, causing excessive temperature changes. In this case, the system will automatically determine that the equivalent depth is too deep and compensate by retracting the needle tip to the appropriate depth. Excessive needle tip advancement causes an excessive temperature response; to restore the temperature response to the target depth, the needle tip must be retracted to reduce the excessively rapid temperature rise. This retraction adjustment avoids the influence of excessively deep test depths on temperature data, ensuring the accuracy of temperature changes. It can precisely control the needle tip depth, improving the consistency and reliability of test data.

[0100] S32054: If the temperature response delay is determined, compensation is made by extending the dwell time.

[0101] Temperature response delay refers to the failure of a temperature change to reach the expected increment within a predetermined time, typically indicating that the test depth was not reached as expected or that heat conduction was slow. When temperature response is delayed, it may be due to the needle not reaching the expected depth or slow heat conduction. In this case, the system will identify it as a temperature response delay and compensate by extending the dwell time, allowing more time for data acquisition. Extending the dwell time ensures sufficient temperature data acquisition and provides more time for temperature response, preventing premature or insufficient data acquisition and ensuring data integrity. In the case of temperature response delay, the control system ensures stable temperature curve acquisition by extending the dwell time. The system adjusts the dwell time based on real-time temperature data feedback until the temperature response stabilizes. The dwell time can be dynamically adjusted according to the degree of temperature change delay. By extending the dwell time, sufficient temperature data acquisition is ensured, preventing temperature changes from skipping before sampling is complete, and guaranteeing the integrity and stability of the temperature data. This method is suitable for situations where the temperature response is slow or heat conduction is uneven during testing.

[0102] In this embodiment, step S32: during the process of the needle penetrating the test piece, detecting the temperature at different depths within the test piece using a built-in thermocouple further includes: S32081 determines the positional consistency of temperature changes by analyzing the positional relationship between hotspot locations and target detection depth in the temperature sequence; Hotspot locations refer to the areas where temperature changes are greatest and most significant during a temperature change process, typically reflecting areas of heat sources or heat accumulation. Location consistency refers to whether the temperature change occurs at a predetermined depth location and conforms to the expected temperature response.

[0103] S33082: If temperature changes occur at non-predetermined locations or are unevenly distributed, it is considered an inconsistent temperature change. A non-predetermined location refers to a temperature change occurring outside the target depth, i.e., exceeding the expected measurement depth range. Inconsistent temperature changes mean that the location or distribution of temperature changes during the test does not match expectations, which may be due to anomalies caused by changes in battery state or shifts in the location of the heat source. During the test, the system compares the location of the temperature change with the preset target depth. If the temperature change occurs at a non-predetermined location (e.g., a rapid temperature change occurring at a shallow location or uneven distribution), it indicates that the location of the heat source has changed, which may be caused by changes in the state of the test piece (such as bulging or heat accumulation).

[0104] S33083: If inconsistent temperature changes are determined, a compensation and adjustment process is triggered, including continuing to advance to a new stopping position, reverting to a qualified position and performing stopping sampling, and extending the stopping time; If the temperature change is determined to be inconsistent (e.g., a shift in the location of the heat source), the control system will trigger a compensation adjustment, using the following methods to correct it: Continue advancing to a new stopping position: If it is determined that the temperature change is too shallow, the needle head will continue to advance until the predetermined target depth is reached; Retract to the appropriate position: If the temperature changes too quickly, it indicates that the needle head has been pushed too deep, and the system will compensate by retracting to the appropriate position; Extended dwell time: If the temperature response is delayed, the system will extend the dwell time to ensure sufficient time for stable acquisition of temperature data.

[0105] S3309: When the temperature change occurs at a predetermined position, it is determined that the consistency meets the preset conditions, and the test continues.

[0106] S32: During the process of the needle penetrating the test piece, the temperature at different depths within the test piece is detected using the built-in thermocouple, including: S32101: During the needle insertion process, real-time temperature change data corresponding to multiple temperature detection points set at different axial positions of the needle are acquired; Multiple temperature detection points refer to multiple temperature measurement positions spaced apart along the needle axis, such as a front detection point near the tip of the needle, a middle detection point in the middle, and a rear detection point near the rear, reflecting the temperature response at different axial positions of the needle. This step uses the temperature responses at multiple locations during the same needle puncture process to construct a spatial comparison, thereby providing basic data for subsequent judgment of temperature differences, the order of temperature rise, and the risk of propulsion disturbance. Otherwise, subsequent speed control can only rely on single-point information, making it difficult to distinguish different operating conditions such as heat source forward movement, heat accumulation and diffusion, or local contact changes.

[0107] The controller can synchronously collect temperatures at each detection point according to a fixed sampling period, forming a timestamped temperature sequence. During data collection, time alignment is performed on different detection points to avoid misjudgments of the sampling order due to asynchronous sampling. Furthermore, the temperature data buffer can be continuously updated during the process, allowing subsequent steps to directly calculate features such as the rate of temperature change or the onset of temperature rise within a preset observation time window. This step enables the continuous acquisition of highly reliable multi-location temperature data, improving the stability and repeatability of subsequent judgments.

[0108] S32102: Determine the propulsion speed control state based on the temperature difference, temperature change rate difference, or temperature change sequence between the multiple temperature detection points; Temperature difference refers to the temperature difference between different detection points at the same moment or at the end of the same observation time window, such as the difference between the temperature of the front detection point and the temperature of the rear detection point. Temperature change rate difference refers to the difference in the rate of temperature change between different detection points, such as calculating the heating rate of the front and rear points separately within the observation time window and then taking the difference. Temperature change sequence refers to which detection point first shows a significant temperature rise or first exceeds a certain temperature rise criterion, thus forming a sequential relationship of front-end response or rear-end response. This step transforms the original temperature sequence into state variables that can be used for control decision-making, enabling the controller to classify the propulsion process into states suitable for acceleration or deceleration using quantification rules.

[0109] During implementation, the temperature rise amplitude, heating rate, and heating start time of each detection point can be calculated within a preset observation time window. Comparison parameters are then constructed, such as the temperature difference and rate difference between the front and rear points, and the time difference between the front and rear detection points reaching the same temperature rise threshold. These comparison parameters are then compared with preset control standards to output the propulsion speed control state, such as high-speed propulsion or low-speed propulsion. This approach simplifies complex thermal response differences into a stable control state, providing a clear basis for subsequent speed switching and reducing erroneous switching caused by instantaneous noise or single-point anomalies.

[0110] If the temperature difference between the front-end and back-end detection points is large, it indicates that the temperature distribution is uneven. The system will choose to advance at a low speed to avoid thermal disturbance caused by advancing too fast.

[0111] Temperature change rate difference and propulsion speed control: If the temperature change rate at the front end is greater than that at the rear end, the system will choose to accelerate propulsion (i.e., the first propulsion speed) to improve propulsion efficiency; if the change rate at the rear end is higher, it indicates that the heat source has shifted, and the system will choose to decelerate propulsion (i.e., the second propulsion speed) to reduce disturbance and improve temperature measurement stability.

[0112] Temperature change sequence and propulsion speed control: If the temperature change at the front end occurs earlier, it indicates that the propulsion has not had a significant impact on the rear area, and the system will choose to accelerate the propulsion; if the temperature change at the rear end occurs earlier, it indicates that the heat source is unevenly distributed, and the system will choose to decelerate the propulsion.

[0113] Specifically, this includes: when the front-end position detection point among the plurality of temperature detection points shows an earlier temperature change or a higher temperature rise rate compared to the rear position detection point, switching to the first propulsion speed; The temperature change is defined as the front-end detection point showing a significant temperature rise or reaching a preset temperature rise criterion first, such as the front-end exceeding a certain increment of the ambient reference temperature. A higher temperature rise rate means that the temperature rise rate of the front-end detection point is higher than that of the rear detection point within the same observation time window. The reasoning behind this condition is that when the thermal response is mainly concentrated at the tip of the needle and its propagation along the axial direction is not yet significant, it indicates that the overall disturbance caused by the advancement is relatively controllable, and no obvious abnormal thermal response has yet appeared in the rear region. In this case, appropriately increasing the advancement speed can improve testing efficiency and quickly reach the subsequent depth sampling position.

[0114] When the controller outputs a control state suitable for acceleration, the propulsion control command is switched to the first propulsion speed, and the temperature difference is continuously monitored to see if the condition is still met. If the condition is continuously met, the first propulsion speed is maintained. The first propulsion speed can be a preset speed level or a target speed value output by the controller, as long as it is greater than the second propulsion speed. This can be combined with a slow start or acceleration-limiting strategy to avoid mechanical shock. The beneficial effect of this step is that it improves propulsion efficiency, reduces invalid waiting time, and increases the number of depth samples that can be completed per unit time without sacrificing temperature measurement stability.

[0115] When the rear position detection point among the plurality of temperature detection points shows an earlier temperature change or a higher temperature rise rate than the front position detection point, or when the temperature difference between the plurality of temperature detection points meets the preset risk judgment condition, the second propulsion speed is switched; wherein, the first propulsion speed is greater than the second propulsion speed.

[0116] An earlier temperature change or a higher rate of temperature rise at the rear indicates abnormal axial propagation of the thermal response or a more intense temperature rise in the rear region. This corresponds to the rearward expansion of heat accumulation, changes in the local structure leading to altered heat conduction paths, or unexpected thermal responses induced by propulsion disturbances. Preset risk assessment conditions can include temperature differences exceeding a certain threshold, rate differences exceeding a certain threshold, or a rapid amplification of temperature differences between front and rear detection points within a short period, indicating that the current temperature distribution is no longer in a stable sampling environment. The purpose of this step is to proactively slow down when potential risk characteristics are detected, thereby reducing propulsion disturbances and improving temperature measurement stability, preventing temperature curve fluctuations or the masking of critical responses due to excessively rapid propulsion.

[0117] Once the controller determines that the conditions for abnormal response or temperature difference risk are met, it switches the propulsion speed to a second propulsion speed. This can be combined with strategies such as extended dwell times and additional dwell positions, along with subsequent slave-level linkage, to ensure temperature data acquisition is completed under more stable propulsion conditions. The second propulsion speed can be set to a lower level or a smaller target speed value. Hold time or hysteresis logic can also be set to prevent frequent switching caused by temperature characteristics fluctuating around the threshold. This step reduces disturbances to the internal thermal field during propulsion, improves temperature sequence consistency, enhances the ability to capture abnormal thermal responses, and thus improves test safety and data reliability.

[0118] The above description is merely a specific embodiment of the present invention. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A multi-physics field testing device for lithium batteries, characterized in that, include: The main body has an internal chamber, and a support platform is provided in the chamber for fixing the sample to be tested; A needle-punching and extrusion device is connected to the main body. The needle-punching and extrusion device includes a driving mechanism and an execution mechanism. The driving mechanism is connected to the execution mechanism in a transmission manner. The execution mechanism is provided with a needle-punching head or an extrusion head at its end. The needle-punching head is provided with a plurality of embedded thermocouples inside. The control cabinet includes a needle-punching and squeezing control device and a data acquisition device. The needle-punching and squeezing control device is electrically connected to the needle-punching and squeezing device, and the data acquisition device is electrically connected to the positive and negative terminals of the sample to be tested, respectively.

2. The lithium battery multiphysics field testing equipment according to claim 1, characterized in that, The needle head has a hollow structure; and / or Several external thermocouples are arranged around the support platform.

3. The lithium battery multiphysics field testing equipment according to claim 1, characterized in that, The plurality of external thermocouples include first thermocouples distributed along a first direction and second thermocouples distributed along a second direction. Every six first thermocouples distributed in a regular hexagonal pattern form a first thermocouple group, and every six second thermocouples distributed in a regular hexagonal pattern form a second thermocouple group.

4. The lithium battery multiphysics field testing equipment according to claim 1, characterized in that, It also includes an infrared camera, which is mounted on the main body and electrically connected to the data acquisition device.

5. The lithium battery multiphysics field testing equipment according to claim 1, characterized in that, It also includes a high-definition camera and an illumination lamp, which are mounted on the main body. The high-definition camera and the sample are isolated by an explosion-proof glass plate. The high-definition camera is electrically connected to the data acquisition device.

6. The lithium battery multiphysics field testing equipment according to claim 1, characterized in that, It also includes a gas pipeline that connects the inside and outside of the chamber, and a valve is provided on the gas pipeline to control the opening and closing of the gas pipeline.

7. The lithium battery multiphysics field testing equipment according to any one of claims 1 to 6, characterized in that, The main body is also provided with a gas collection port, which is used to collect the gas generated during the detection process.

8. A multi-physics field testing method for lithium batteries, characterized in that, The method of testing using the lithium battery multiphysics testing equipment according to any one of claims 1 to 7 includes: Obtain the needle penetration test parameters and / or compression test parameters; The needle head is controlled to puncture the test piece according to the needle puncture test parameters and / or the extrusion head is controlled to extrude the test piece according to the extrusion test parameters; Collect test data, which includes at least the internal temperature of the test piece, the ambient temperature of the test piece, the voltage during the test time, and the internal resistance of the test piece. Multiphysics analysis was performed on the failure process of the test piece based on the test data.

9. The multiphysics field testing method for lithium batteries according to claim 8, characterized in that, The collected test data includes at least the internal temperature of the test piece, the ambient temperature of the test piece, the voltage of the test piece, and the internal resistance of the test piece. The voltage and internal resistance of the test piece are obtained using a voltage and internal resistance acquisition line. During the process of the needle penetrating the test piece, the temperature at different depths inside the test piece is detected by the built-in thermocouple. The temperature distribution around the test specimen is detected using an external thermocouple. The gas generated by the battery during thermal runaway combustion and explosion of the test piece is collected using a gas collection port; Use high-definition cameras to acquire real-time images of thermal runaway; Infrared cameras are used to acquire infrared images of the heat distribution of the test specimen before thermal runaway combustion and explosion.

10. The multiphysics testing method for lithium batteries according to claim 9, characterized in that, The process of inserting the needle into the test piece, and using a built-in thermocouple to detect the temperature at different depths within the test piece, includes: Based on the preset detection targets, the detection depth of multiple targets and the initial step size and initial dwell time of the propulsion control are determined to obtain the preset control parameters; According to the preset control parameters, the needle head is controlled to advance to the current stopping position and stop sampling is performed to obtain the temperature sequence of the current stopping position and its corresponding depth information; If the current location is the first location visited, the temperature sequence of the current location is recorded as the baseline temperature data; If the current stopping position is not the first stopping position, the temperature change amplitude between adjacent stopping positions is obtained based on the temperature sequence and the temperature sequence corresponding to the previous stopping positions in the same acupuncture test process, and the first change feature is obtained. Based on the changes in the temperature sequence within a preset observation time window, the rate of temperature change is obtained, and a second change feature is derived. The temperature change state is determined based on the first change feature and the second change feature to obtain the temperature change state. The needle advance step size or dwell time is switched according to the temperature change status to update the advance control parameters and control the needle head to advance and sample at the next dwell position.

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