Early smoke signature test platform for battery thermal runaway and measurement method thereof

Abstract

The present application belongs to the field of testing instruments, and particularly relates to a battery thermal runaway early smoke characteristic testing platform and a battery thermal runaway early smoke characteristic measurement method. The testing platform is used for measuring the corresponding early smoke characteristics of a battery under test under a thermal runaway state caused by different triggering conditions. The platform comprises a test container, an air flow organization system, a wind speed sensor, a sound pressure sensor, a gas pressure sensor, a thermal runaway triggering mechanism, a flue gas online analysis assembly, a sampling device, an electrical measurement assembly, and an upper computer. The test container comprises a combustion chamber and a flue. The air flow organization system introduces background gas into the test container, and makes the background gas enter from the bottom of the combustion chamber and rise upward below the battery, and finally be discharged along the end section of the flue. The flue gas online analysis assembly comprises a first thermocouple sensor, a gas analyzer, and a VOC monitor. The present application solves the problems of great difficulty and high risk in the research of battery thermal runaway early smoke characteristics.

Description

Technical Field

[0001] This invention belongs to the field of testing instruments, specifically relating to a testing platform for early flue gas characteristics of battery thermal runaway and a method for measuring early flue gas characteristics of battery thermal runaway. Background Technology

[0002] The rapid advancements in rechargeable battery technologies, such as lithium-ion batteries, have propelled the electronics and new energy vehicle industries onto a fast track of development. With environmental awareness growing stronger, new energy vehicles, represented by electric vehicles, are poised to directly replace gasoline-powered vehicles. In this trend, improving battery energy density and charging performance, as well as enhancing battery safety, have become critical technical challenges that engineers urgently need to address.

[0003] However, fires caused by battery thermal runaway seriously threaten the safety of electrical equipment, making safety a crucial factor restricting its development. Considering the rapid development, irreversibility, and severe hazards of fires caused by battery thermal runaway, early detection of battery thermal runaway to allow reaction time for battery safety or fire protection is an important research direction in the field of battery safety.

[0004] For rechargeable batteries, such as lithium-ion batteries, thermal runaway typically releases gases like hydrogen, methane, and carbon monoxide. Detonation or open flames also produce particulate smoke. Therefore, analyzing the smoke characteristics in the early stages of battery thermal runaway and designing corresponding detectors should enable timely monitoring of thermal runaway risks. Furthermore, considering the diversity of rechargeable batteries and the numerous causes of thermal runaway, it is essential to classify the early characteristics of different battery types under various conditions. In particular, the smoke characteristics and combustion states differ significantly at different stages after thermal runaway or even detonation; therefore, accurate classification of these characteristics is also crucial.

[0005] However, under current technological conditions, there is no dedicated testing platform for studying battery thermal runaway. Technicians typically use existing combustion testing equipment used for various industrial product performance tests, or they build their own small testing platforms. This not only carries high safety risks but also makes it difficult to obtain effective, high-precision data. In summary, existing lithium battery thermal runaway testing devices cannot effectively identify the early-stage smoke characteristics of lithium battery thermal runaway. Those skilled in the art urgently need a highly safe and comprehensive battery thermal runaway smoke testing platform to study the characteristic patterns of early-stage battery thermal runaway. Summary of the Invention

[0006] To address the challenges of studying the early-stage flue gas characteristics of battery thermal runaway, including its high risk and lack of dedicated testing instruments, this invention provides a testing platform for the early-stage flue gas characteristics of battery thermal runaway, as well as a method for measuring these characteristics.

[0007] This invention is achieved using the following technical solution:

[0008] An early flue gas characteristic testing platform for battery thermal runaway is disclosed, which is used to measure the early flue gas characteristics of the battery under test under different initiation conditions caused by thermal runaway. This early flue gas characteristic testing platform includes: a test container, an airflow organization system, a wind speed sensor, a sound pressure sensor, a gas pressure sensor, a runaway initiation mechanism, an online flue gas analysis component, a sampling device, an electrical measurement component, and a host computer.

[0009] The test container includes a combustion chamber and a flue. A battery clamp is located in the center of the combustion chamber; a gas inlet is located at the bottom of the combustion chamber, and a funnel-shaped smoke hood is located at the top. The gas outlet at the top of the smoke hood is connected to a horizontally placed flue. A flow stabilizing pipe is installed at the interface between the flue and the combustion chamber, and multiple through holes for equipment installation are provided on the outer wall of the flue.

[0010] The airflow organization system is used to introduce background gas into the test container and create a gas convection environment in which the background gas enters from the bottom of the combustion chamber, rises vertically upward under the battery clamp, and finally exits through the outlet at the end of the flue.

[0011] The wind speed sensor is installed 10 cm downstream of the flow stabilizer in the flue. The sound pressure sensor is installed in the combustion chamber and is used to measure noise information during battery thermal runaway. The air pressure sensor is installed in the combustion chamber and is used to measure instantaneous ambient air pressure data during battery thermal runaway.

[0012] The runaway triggering mechanism is installed at the battery clamp. The runaway triggering mechanism includes a needle puncture actuator, a squeeze actuator, and a heating device, which are used to perform needle puncture, squeeze, and heating operations on the battery to be tested, respectively.

[0013] The flue gas online analysis component includes a first thermocouple sensor, a gas analyzer, and a VOC monitor. The instruments in the flue gas online analysis component are installed in various through-holes on the outer wall of the flue, with the detection elements inserted into the flue. The first thermocouple sensor is located at the front end of the flue, closest to the flow stabilizer, while the gas analyzer and VOC monitor are located on the side relatively behind the first thermocouple sensor.

[0014] The sampling device includes a smoke particle sampling device and a flue gas sampling device; the instruments in the sampling device are installed in through holes on the outer wall of the flue and are located near the end of the flue.

[0015] The electrical measurement assembly is mounted in the battery fixture. It is electrically connected to the battery under test via electrode plates and is used to simulate the charging, discharging, and natural states of the battery, acquiring its electrical parameters during the measurement process. Furthermore, the electrical measurement assembly is also used to simulate short-circuit faults in the battery.

[0016] The host computer is electrically connected to the airflow organization system, wind speed sensor, sound pressure sensor, air pressure sensor, runaway initiation mechanism, online analysis mechanism, sampling device, and electrical measurement components. The host computer serves as the control and data processing center of the entire test platform. It can issue control commands to other instruments or actuators, collect detection data from instruments and sensors, analyze and process various types of data, and ultimately generate an analysis report on the early characteristics of battery thermal runaway. In this invention, the host computer is used for:

[0017] 1. The airflow organization system generates a uniform convection background gas environment in the combustion chamber that meets the preset conditions, and ensures that the measured value of the wind speed sensor is 0.2±0.02m / s in the initial state.

[0018] 2. The control runaway triggering mechanism or electrical measurement component triggers thermal runaway of the battery under test according to the measurement task, and determines the triggering time of thermal runaway by combining the sampling data of the acoustic pressure sensor.

[0019] 3. Obtain real-time measurement data from online monitoring components, electrical measurement components, and barometric pressure sensors.

[0020] IV. Obtain the sample detection results of the samples collected by the sampling device in the offline device.

[0021] 5. Conduct a comprehensive analysis of the sample data measured online and the detection results of the sample offline analysis, and generate a complete early flue gas characteristic analysis report of battery thermal runaway.

[0022] As a further improvement of the present invention, the test container also includes at least one openable and closable sealed door and at least one transparent observation window. The interior of the test container is provided with a fire-resistant layer.

[0023] In addition, a binocular camera equipped with both infrared and full-color cameras was installed outside the observation window of the test container. The binocular camera was used to record image data during the thermal runaway experiment.

[0024] As a further improvement of the present invention, the airflow organization system includes: a high-pressure gas cylinder, a valve body, a gas flow meter, a centrifugal fan, and a low-speed axial flow fan. The high-pressure gas cylinder contains the required background gas. The valve body is used to control the valve opening of the high-pressure gas cylinder to discharge the background gas into the combustion chamber. The gas flow meter is installed at the gas inlet of the combustion chamber and the outlet of the flue to measure the gas flow rate at both locations; the centrifugal fan is installed at the end of the flue to discharge the gas in the combustion chamber from the test container. The low-speed axial flow fan is installed at the bottom of the combustion chamber, directly opposite the battery clamp, and is used to generate vertically upward lift.

[0025] As a further improvement of the present invention, the background gas is nitrogen, or a mixture of nitrogen and oxygen in a molar ratio of 8:2 after being mixed by a mixing valve.

[0026] As a further improvement of the present invention, the battery clamp is also equipped with a second thermocouple sensor and a pressure gauge. The second thermocouple sensor is used to measure the surface temperature of the battery under test during thermal runaway. The pressure gauge is used to measure the expansion pressure of the battery under test during thermal runaway.

[0027] As a further improvement of the present invention, the battery clamp includes a mounting groove, and the electric heating element of the heating device is installed inside the battery clamp near the bottom wall of the mounting groove. The extrusion actuator is installed directly above the battery clamp and can rotate horizontally relative to the battery clamp. The extrusion actuator employs a downward-feeding hydraulic mechanism; and after a steel needle is installed at the front end of the pressure head of the hydraulic mechanism, the desired needle-punching actuator is formed.

[0028] As a further improvement of the present invention, the smoke particle sampling device employs a copper mesh carbon film. The acquired smoke particle samples are analyzed using a TEM electron microscope to obtain information on the composition, structure (such as morphology and particle size), and concentration of the particles contained in the flue gas.

[0029] The flue gas sampling device includes a sampling pump, a sampling tube, and a vacuum bag. The sampling pump extracts sample gas from the flue through the sampling tube and stores it in the vacuum bag. The collected gas samples are analyzed using gas chromatography-mass spectrometry (GC-MS).

[0030] As a further improvement of the present invention, the early flue gas characteristic testing platform also includes a safety system, which is used to spray perfluorohexanone or liquid nitrogen into the combustion chamber after the test to achieve fire prevention and cooling.

[0031] This invention also includes a method for measuring the early-stage flue gas characteristics of a battery in thermal runaway, which is used to perform early-stage flue gas characteristic analysis of a battery under different thermal runaway states using the aforementioned early-stage flue gas characteristic testing platform for battery thermal runaway; the measurement method includes the following steps:

[0032] I. Debugging Phase:

[0033] S1: Install the battery to be tested on the battery clamp in the combustion chamber and seal the combustion chamber.

[0034] S2: Replace the gas inside the test container with background gas to form a stable and uniform gas convection environment, while controlling the gas flow rate in the flue.

[0035] S3: Use detection instruments or sensors to continuously monitor environmental parameters at various points in the combustion chamber and flue, and monitor the electrical parameters of the battery.

[0036] Environmental parameters include: combustion chamber sound pressure, combustion chamber instantaneous gas pressure, flue gas temperature, flue wind speed, and the composition and concentration of flue gas.

[0037] II. Actual Measurement Phase

[0038] S4: According to the preset measurement task, one or more operations such as heating, squeezing, puncturing, and short circuit are performed to induce thermal runaway of the battery under test.

[0039] S5: Combine the sound pressure measurement data in the combustion chamber with the execution time of heating, squeezing, puncture or short circuit operations to determine the moment when thermal runaway of the battery under test occurs.

[0040] S6: Based on the precise response time of each detection instrument or sensor, the detection data is divided into the pre-thermal runaway stage and the post-thermal runaway stage. During the window period, smoke particles and flue gas in the flue are sampled using a sampling device; the window period refers to the time when the early flue gas generated by battery thermal runaway flows through the sampling device.

[0041] S7: After obtaining the required test data, stop the ventilation to the combustion chamber, extinguish and cool the battery under test until the risk of battery explosion is eliminated.

[0042] S8: Perform offline detection on smoke particles and smoke samples obtained by the sampling device.

[0043] S9: By combining the process data of the pre- and post-thermal runaway stages obtained from the online detection process with the experimental data from the offline detection, the early smoke characteristics of the battery under test in the thermal runaway state are analyzed.

[0044] As a further part of the present invention, in step S3, a VOC monitor and a gas analyzer are used to monitor the composition and concentration of flue gas in concert, and a first thermocouple sensor is used to monitor the temperature of flue gas.

[0045] In step S6, the precise response time of the VOC monitor is:

[0046]

[0047] In the above formula, t VOC s1 is the initial response time of the VOC monitor; s2 is the distance between the VOC monitor and the current stabilizing tube; f is the wind speed 10cm behind the current stabilizing tube under thermal runaway conditions of the battery under test.

[0048] The precise response time of the gas analyzer is:

[0049]

[0050] In the above formula, t gas s1 is the initial response time of the gas analyzer; s2 is the distance between the gas analyzer and the flow stabilizing tube; d is the diameter of the sampling tube in the gas analyzer; l is the length of the sampling tube in the gas analyzer; and Q is the flow rate value corresponding to the unit suction force of the gas analyzer.

[0051] The precise response time of the first thermocouple sensor is:

[0052]

[0053] In the above formula, t T s is the initial response time of the thermocouple; s3 is the distance between the first thermocouple sensor and the flow regulator.

[0054] The technical solution provided by this invention has the following beneficial effects:

[0055] The battery thermal runaway early-stage flue gas characteristic testing platform provided by this invention integrates measuring instruments for various indicators required for battery thermal runaway measurement. The platform's structural design and control system have been optimized, enabling highly automated completion of complex operations and intricate data processing during battery thermal runaway experiments. This ultimately reduces safety hazards during the experiment and improves the accuracy and effectiveness of data acquisition. This powerful testing platform is suitable for testing various battery models and under different thermal runaway initiation conditions, thus possessing high practical value.

[0056] The test platform designed in this invention employs a special airflow organization system. This system can generate a uniform, singular temperature airflow environment formed by background gas inside the test container. This not only drives the flue gas generated by battery thermal runaway to flow towards the monitoring instruments at the back end, but also reduces the interference of ambient gas on the test experiment. Furthermore, when the flue gas production flow rate is low, a positive pressure air supply mode is used to organize the airflow, solving the problem of the impact of uneven flue gas flow on the accuracy of battery thermal runaway flue gas measurement. Therefore, it is very suitable for studying the flue gas characteristics in the early stages of battery thermal runaway.

[0057] Compared with traditional testing methods, the testing platform of this invention can also effectively control the convection process of airflow, thereby facilitating precise control of the response time of each testing instrument. It can effectively avoid the influence of uneven flue gas flow velocity or stagnation in the combustion chamber on the test results, and ultimately significantly improve the detection accuracy and reliability of various data indicators. Attached Figure Description

[0058] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0059] Figure 1 This is a structural and equipment installation layout diagram of an early flue gas characteristic testing platform for battery thermal runaway provided in Embodiment 1 of the present invention.

[0060] Figure 2 This is a block diagram of the control system in the early flue gas characteristic test platform for battery thermal runaway in Embodiment 1 of the present invention.

[0061] Figure 3 This is a schematic diagram of the test container in a test platform for early flue gas characteristics of battery thermal runaway.

[0062] Figure 4 This is a structural design diagram of the flue in a test platform for early flue gas characteristics of battery thermal runaway.

[0063] Figure 5 The diagram shows the structural layout of the airflow organization system within the test container of a test platform for early flue gas characteristics of battery thermal runaway.

[0064] Figure 6 This is a schematic diagram of the assembly of the cylindrical battery to be tested and its battery fixture in Example 1.

[0065] Figure 7 This is a flowchart of the steps for measuring the early-stage flue gas characteristics of a battery thermal runaway as provided in Embodiment 2 of the present invention.

[0066] The diagram is marked as follows:

[0067] 1. Test container; 10. Sealed door; 11. Battery clamp; 12. Flue; 13. Wind speed sensor; 14. Sound pressure sensor; 15. Air pressure sensor; 16. Runaway triggering mechanism; 17. Flue gas online analysis component; 19. Electrical measurement component; 20. Second thermocouple sensor; 21. Pressure gauge; 22. Airflow organization system; 100. Host computer; 101. Observation window; 110. Smoke hood; 120. Flow stabilizer; 121. Lifting eye bolt; 171. First thermocouple sensor; 172. Gas analyzer; 173. VOC monitor; 181. Sampling pump; 182. Smoke particle sampling device; 201. Binocular camera; 221. High-pressure gas cylinder; 222. Valve body; 223. Gas flow meter; 224. Low-speed axial flow fan; 225. Centrifugal fan. Detailed Implementation

[0068] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention.

[0069] Example 1

[0070] This embodiment provides a testing platform for early-stage flue gas characteristics of battery thermal runaway, used to measure the early-stage flue gas characteristics of the battery under test under different initiation conditions causing thermal runaway. The testing platform provided in this embodiment is an automated testing platform operated under operator supervision. The operation control of the battery thermal runaway process is automatically executed by the testing platform, or executed according to plan under remote control by the operator. The acquisition and analysis of test data are automatically completed by the platform. The operator only needs to remotely issue test commands according to the requirements of the operation manual. Specifically, this testing platform supports testing battery thermal runaway initiation conditions including battery puncture by a sharp object, battery compression by a blunt object, battery overheating, battery short circuit, and combinations of the above initiation conditions leading to battery thermal runaway failures.

[0071] like Figure 1 As shown, the early flue gas characteristic testing platform provided in this embodiment includes: a test container 1, an airflow organization system 22, a wind speed sensor 13, a sound pressure sensor 15, a gas pressure sensor, a runaway initiation mechanism 16, an online flue gas analysis component 17, a sampling device, an electrical measurement component 19, and a host computer 100. Figure 2As shown, the host computer 100 is electrically connected to the airflow organization system 22, wind speed sensor 13, sound pressure sensor 15, air pressure sensor, runaway initiation mechanism 16, online analysis mechanism, sampling device, and electrical measurement component 19. The host computer 100 is the control center and data processing center of the entire test platform. The host computer 100 can issue control commands to other instruments or actuators, or collect detection data from instruments and sensors, and analyze and process various types of data to ultimately produce an analysis report on the early characteristics of battery thermal runaway.

[0072] Specifically, such as Figure 3 As shown, the test container 1 includes a combustion chamber and a flue 12. A battery clamp 11 is disposed in the center of the combustion chamber and is connected to the inner wall of the combustion chamber in the test container 1 by a support rod. The battery clamp 11 is used to hold the battery under test and keep the battery electrically connected to the electrical measurement component 19 during the test. The structure of the battery clamp 11 can be designed according to the shape of the battery under test. For example, pouch batteries or prismatic batteries are suitable for placement on the battery clamp 11 with mounting slots, while improving the versatility of the test platform for different types of batteries. The battery clamp 11 should be designed to be replaceable. A gas inlet is provided at the bottom of the combustion chamber, and a smoke hood 110 in the shape of an inverted funnel is provided at the top. The gas outlet at the top of the smoke hood 110 is connected to a horizontally placed flue 12. In addition, the test container 1 of this embodiment also includes at least one openable and closable sealed door 10 and at least one transparent observation window 101. The sealed door 10 facilitates safety checks of the combustion chamber interior by test personnel at the beginning and end of the test, and ensures the correct installation of the battery under test onto the battery clamp 11. The observation window 101, made of high-temperature resistant explosion-proof glass, allows test personnel to observe the entire process of the battery's thermal runaway within the combustion chamber during the test. Of course, to support observation of the combustion chamber, a lighting system should also be provided. Furthermore, this embodiment incorporates fire-resistant layers on the inner wall of the test container 1 and on the surfaces of certain cables or equipment to prevent damage to related instruments and equipment from the deflagration of the battery under test.

[0073] Specifically, in the solution provided in this embodiment, the required test container 1 is prepared using stainless steel sheet with high temperature resistance and explosion-proof properties. In the test container 1, the dimensions of the battery combustion chamber are designed according to the actual experimental space requirements. In this embodiment, it is recommended that the inner cavity have a square structure with dimensions of 1.8m × 1.8m × 1.8m. The recommended dimensions for the observation window 101 are 0.4m × 0.3m, and the recommended dimensions for the sealing door 10 are 1m × 1.5m. The recommended dimensions for the upper section of the top smoke hood 110 are 0.8m, and the recommended height is 0.9m.

[0074] In this embodiment, as Figure 4As shown, the exhaust pipe is a square pipe, and the recommended length in this embodiment is 3m, with a recommended cross-sectional size of 0.4m × 0.4m. A flow stabilizing pipe 120 is installed at the interface between the flue 12 and the combustion chamber. The flow stabilizing pipe 120 is a pipe containing uniformly distributed mesh-like channels. The flow stabilizing pipe 120 can convert the "turbulence" at the smoke hood 110 into a uniform "stabilized flow" with the direction of motion parallel to the extension direction of the exhaust pipe through a series of uniformly arranged mesh-like channels. In this embodiment, multiple through holes for installing various testing instruments are uniformly opened on the outer wall of the flue 12; when the through holes are not in use, they can be sealed using eye bolts 121.

[0075] The airflow organization system 22 provided in this embodiment is mainly used to introduce background gas into the test container 1 and form a gas convection environment in which the background gas enters from the bottom of the combustion chamber, rises vertically upward under the battery clamp 11, and is finally discharged through the outlet of the end section of the flue 12.

[0076] Specifically, such as Figure 5 As shown, the airflow organization system 22 includes: a high-pressure gas cylinder 221, a valve body 222, a gas flow meter 223, a centrifugal fan 225, and a low-speed axial flow fan 224. The high-pressure gas cylinder 221 contains the required background gas. The valve body 222 is used to control the valve opening of the high-pressure gas cylinder 221 to discharge the background gas into the combustion chamber. The gas flow meter 223 is installed at the gas inlet of the combustion chamber and the outlet of the flue 12 to measure the gas flow rate at both locations; the centrifugal fan 225 is installed at the end of the flue 12 to discharge the gas in the combustion chamber from the test container 1. The low-speed axial flow fan 224 is installed at the bottom of the combustion chamber, directly opposite the battery clamp 11, and is used to generate vertical upward lift.

[0077] During the experiment, the high-pressure gas cylinder 221 continuously releases background gas into the combustion chamber from the gas inlet at the bottom of the combustion chamber. After reaching the bottom, the gas is lifted upwards by the low-speed axial flow fan 224, and the flue gas generated in the battery body under thermal runaway state in the battery clamp 11 is "entrained" to the upper smoke collection hood 110. At the same time, the suction effect of the centrifugal fan 225 at the end of the flue 12 will make the gas pressure inside the flue 12 lower than the gas pressure in the combustion chamber, which will cause the mixed flue gas in the smoke collection hood 110 to be continuously "drawn" into the flue 12 through the flow stabilizer pipe 120, and finally discharged from the outlet at the end of the flue 12.

[0078] In this embodiment, the gas flow rate within the flue 12 can be effectively regulated by jointly controlling the opening of valve body 222, centrifugal fan 225, and low-speed axial flow fan 224. Specifically, the test platform in this embodiment requires the wind speed within the flue 12 to be maintained at 0.2 ± 0.02 m / s during the test. To monitor the flue gas flow rate, an anemometer 13 is installed within the flue 12. Specifically, the anemometer 13 is installed 10 cm downstream of the flow stabilizing pipe 120 in the flue 12.

[0079] In the airflow organization system 22 of this embodiment, two gas flow meters 223 are used to measure the flow rate of the background gas introduced into the system and the flow rate of the gas discharged from the system, respectively. The gas flow rates measured by the two should be approximately the same in non-test conditions, while the flow rate difference that occurs in test conditions is caused by the smoke generated by the combustion state after thermal runaway of the battery.

[0080] The background gas introduced into the combustion chamber during the testing phase of the test platform in this embodiment serves two main purposes:

[0081] First, the gas in the combustion chamber is "purified" to prevent the original or complex external gas composition in the combustion chamber from affecting the battery thermal runaway or combustion process. At the same time, the original complex gas composition in the combustion chamber is prevented from interfering with the analysis of early flue gas characteristics after combustion.

[0082] Secondly, considering the relatively small amount of flue gas generated in the early stage of battery thermal runaway, the airflow is organized using background gas as the carrier gas to ensure that all flue gas can be "loaded" into flue 12, thereby achieving accurate measurement of early flue gas characteristics; and avoiding the accumulation of early flue gas in the combustion chamber and mixing with flue gas from other periods, which would affect the reliability of the final test results.

[0083] In this embodiment, for the aforementioned objectives, the background gas should be selected to have a composition and density similar to air, and should not produce significant flame-retardant or combustion-supporting gains. Simultaneously, the background gas should be easily distinguishable and detectable, and easy to filter signals during subsequent data analysis. Under these conditions, this embodiment selects pure nitrogen as the background gas. Furthermore, in other embodiments, a mixture of nitrogen and oxygen in a molar ratio of 8:2 can also be selected as the background gas. When using a mixed gas, the airflow organization system 22 should employ dual gas cylinders containing nitrogen and oxygen respectively, and a mixing valve should be used to uniformly mix the gases released from the two cylinders before introducing them into the gas inlet at the bottom of the combustion chamber.

[0084] In the solution provided in this embodiment, the sound pressure sensor 15 is installed in the combustion chamber and is used to measure the noise information during the battery thermal runaway process. The air pressure sensor is installed in the combustion chamber and is used to measure the instantaneous ambient air pressure status data during the battery thermal runaway process. The runaway initiation mechanism 16 is installed at the battery clamp 11. The runaway initiation mechanism 16 includes a needle penetration actuator, a compression actuator, and a heating device, which are used to perform needle penetration, compression, and heating operations on the battery to be tested, respectively.

[0085] In the product structure design of the early flue gas characteristic testing platform in this embodiment, the battery clamp 11 includes a mounting slot. The electric heating tube in the heating device is installed inside the battery clamp 11 near the bottom wall of the mounting slot. The electric heating tube can heat the mounting slot in the battery clamp 11 to a preset temperature, thereby causing the battery under test to experience thermal runaway due to excessive surface temperature. The extrusion actuator and the needle penetration actuator are actually implemented by a vertical hydraulic mechanism, which is installed directly above the battery clamp 11. When the hydraulic mechanism feeds downward, the pressure head at the lower end applies compressive stress to the battery under test in the mounting slot. In addition, technicians can adjust the point of application of the compressive stress and the extrusion method by changing the pressure head with different properties or structures. Furthermore, the required needle penetration actuator can be constructed by simply installing a steel needle at the front end of the pressure head of the hydraulic mechanism to perform a needle penetration test on the battery.

[0086] Meanwhile, it should be noted that, in order to avoid the hydraulic mechanism interfering with the convection path of the flue gas generated by battery thermal runaway, in a more optimized solution, the hydraulic mechanism in this embodiment can be connected in a movable manner that can rotate horizontally relative to the battery clamp 11. During the squeezing or piercing action, the hydraulic mechanism is rotated to be directly above the battery clamp 11. After the piercing or squeezing action is completed, the hydraulic mechanism is raised upwards and rotated back to a position away from directly above the battery clamp 11.

[0087] The electrical measurement component 19 is installed in the battery holder 11. The electrical measurement component 19 is electrically connected to the battery under test via electrode plates. The electrical measurement component 19 is used to simulate the charging, discharging, and natural states of the battery under test, and to acquire the battery's electrical parameters during the measurement process. Furthermore, the electrical measurement component 19 is also used to simulate short-circuit faults in the battery.

[0088] In other more optimized technical solutions, a second thermocouple sensor 20 and a pressure gauge 21 can also be installed on the battery clamp 11. The second thermocouple sensor 20 is used to measure the surface temperature of the battery under test during thermal runaway. The pressure gauge 21 is used to measure the expansion pressure of the battery under test during thermal runaway. The measurement data of the second thermocouple sensor 20 and the pressure gauge 21 mainly show the temperature and morphological changes of the battery body. This characteristic data has the following different uses: (1) The surface temperature and deformation of the battery body are themselves one of the target observation parameters in the thermal runaway process of the battery. (2) In the process of measuring the early flue gas characteristics of the battery thermal runaway, the above two characteristics can also be used as one of the criteria for evaluating whether the battery has undergone thermal runaway.

[0089] In the solution provided in this embodiment, the criteria for determining whether battery thermal runaway occurs under different initiation conditions are different. For example, for lithium batteries, since their resistance to puncture is generally poor, if the battery pack under test is penetrated, it will most likely directly trigger battery thermal runaway. For battery thermal runaway caused by compression or heating, it will be affected by the deformation of compressive stress and the temperature rise of the surface. Thermal runaway will only occur when the deformation or temperature rise exceeds a preset limit. In this case, it is necessary to combine the data from the acoustic pressure sensor 15 to make a comprehensive judgment on whether battery thermal runaway has occurred. Generally speaking, after thermal runaway, the battery usually undergoes a violent chemical reaction, leading to battery bulging or even explosion. Therefore, in this test, as long as a brief but relatively intense acoustic pressure signal is detected, it can be determined that the battery has experienced thermal runaway at the corresponding moment.

[0090] In this embodiment, after obtaining the battery surface temperature and expansion pressure, the sound pressure data, battery surface temperature, and expansion pressure can be used together to more reliably analyze when the battery thermal runaway occurs. This is of great significance for more accurately determining whether the collected flue gas characteristics belong to the early characteristics of battery thermal runaway.

[0091] The flue gas online analysis component 17 in this embodiment includes a first thermocouple sensor 171, a gas analyzer 172, and a VOC monitor 173. The instruments in the flue gas online analysis component 17 are installed in various through holes on the outer wall of the flue 12, and the detection elements are inserted into the flue 12. The first thermocouple sensor 171 is located at the front end of the flue 12, closest to the flow stabilizer 120, and is mainly used to test the temperature of the flue gas in the flue 12. The gas analyzer 172 and the VOC monitor 173 are located on the side relative to the first thermocouple sensor 171. The gas analyzer 172 and the VOC monitor have different sensitivities to different gases and also differ in their quantitative analysis capabilities. In this embodiment, by simultaneously installing two online gas composition and concentration analyzers, they can complement each other, jointly detecting the complex gas composition and concentration generated during battery thermal runaway. Of course, for gas components that the two online analyzers mentioned above still cannot effectively distinguish in this embodiment, it is necessary to use a more powerful gas chromatography-mass spectrometry (GC-MS) instrument to perform offline analysis on the collected gas samples to obtain the results.

[0092] The sampling device includes a smoke particle sampling device 182 and a flue gas sampling device; the smoke particle sampling device 182 employs a copper mesh carbon film. The acquired smoke particle samples are analyzed using a TEM electron microscope to obtain information on the composition, structure (such as morphology and particle size), and concentration of the particles contained in the flue gas.

[0093] The flue gas sampling device includes a sampling pump 181, a sampling tube, and a vacuum bag. The sampling pump 181 extracts sample gas from the flue 12 through the sampling tube and stores it in the vacuum bag. The collected gas samples are analyzed by gas chromatography-mass spectrometry (GC-MS).

[0094] The instruments in the sampling device are installed in through holes on the outer wall of the flue 12, near the end of the flue 12. The special design of the sampling device's installation position is mainly to reduce the impact on the detection accuracy of the instruments in the flue gas online analysis component 17. Therefore, sampling is performed after the aforementioned instruments have completed data acquisition, so as to obtain richer sample data using the collected smoke or flue gas samples.

[0095] In the early flue gas characteristic testing platform of this embodiment, the role of the host computer 100 during the execution of the testing task can be roughly divided into the following points:

[0096] 1. The airflow organization system 22 generates a uniform convection background gas environment in the combustion chamber that meets the preset conditions, and ensures that the measured value of the wind speed sensor 13 is 0.2±0.02m / s in the initial state.

[0097] 2. The runaway triggering mechanism 16 or the electrical measurement component 19 triggers thermal runaway of the battery under test according to the needs of the measurement task, and determines the triggering time of thermal runaway by combining the sampling data of the acoustic pressure sensor 15.

[0098] 3. Acquire real-time measurement data from the online monitoring component, electrical measurement component 19, and barometric pressure sensor.

[0099] IV. Obtain the sample detection results of the samples collected by the sampling device in the offline device.

[0100] 5. Conduct a comprehensive analysis of the sample data measured online and the detection results of the sample offline analysis, and generate a complete early flue gas characteristic analysis report of battery thermal runaway.

[0101] In the solution provided in this embodiment, the early flue gas characteristic testing platform may also include a safety system. This safety system is used to inject liquid perfluorohexanone or liquid nitrogen into the combustion chamber after the test to achieve fire prevention and cooling. The function of the safety system is essentially to suppress the thermal runaway state of the battery under test after the test, reducing the risk of further deflagration or explosion, or minimizing the damage to the battery under test that has already deflagrated or exploded. Considering the large number of instruments and equipment arranged in the combustion chamber, this embodiment selects perfluorohexanone and liquid nitrogen, which can both cool and suppress combustion, as fire prevention gases.

[0102] Furthermore, in a more optimized embodiment, a binocular camera 201 equipped with both infrared and full-color cameras can be installed outside the observation window 101 of the test container 1. The binocular camera 201 can record image data of the battery under test throughout the thermal runaway experiment, allowing researchers to further study the visual characteristics of different stages after the battery's thermal runaway.

[0103] The following section elaborates on the solution provided in this embodiment, taking into account the actual operation method and process of the aforementioned battery thermal runaway early flue gas characteristic testing platform:

[0104] Suppose a user needs to perform a thermal runaway test under nail penetration conditions on a cylindrical 18650 battery, they can first open the combustion chamber door and directly fix the battery in place, such as... Figure 6 The battery is clamped onto a U-shaped lock-like battery holder 11; then the hatch is closed. Next, the equipment automatically replaces the gas inside the test container 1 through the airflow organization system 22 and controls the airflow speed in the flue 12 to reach the preset index. During this process, the flue gas online analysis component 17 will start working to determine the initial data of various monitoring indicators in the test environment under the condition that the battery has not experienced thermal runaway. Once the data stabilizes, the test platform will remind the operator that needle puncture can begin.

[0105] After the tester receives the notification message, they issue a needle-puncture command to the test platform. The test platform then uses the runaway initiation mechanism 16 to puncture the battery. Once the puncture is complete, the runaway initiation mechanism 16 automatically resets. Simultaneously, the controller accurately determines the precise moment when the battery experiences thermal runaway based on the timing of the runaway needle-puncture actuator's action and the changes in monitoring data from the sound pressure sensor 15, the second thermocouple sensor 20, or the pressure gauge 21.

[0106] After battery thermal runaway occurs, the flue gas generated by the violent chemical reaction enters the flue 12 from the combustion chamber under the "load" of the background gas. The detection signals of the various measuring instruments installed in the flue 12 will change, and these detection data will be output to the host computer 100. When the flue gas generated in the early stage of battery thermal runaway reaches the sampling state installation position, the controller controls these sampling states to complete the sample collection within their respective sampling windows, and sends the samples to the professional instruments at the back end for offline analysis after the test.

[0107] After the test is completed, the host computer 100 will determine the data corresponding to the early stage of thermal runaway in the test signal based on the time of occurrence of battery thermal runaway and the precise response time of different measuring instruments; and use the relevant signals of the battery under the condition of no thermal runaway acquired in the early stage to correct the collected early thermal runaway data.

[0108] Example 2

[0109] This embodiment provides a method for measuring the early-stage flue gas characteristics of a battery in thermal runaway. This method primarily utilizes the early-stage flue gas characteristic testing platform for battery thermal runaway described in Embodiment 1 to analyze the early-stage flue gas characteristics of a battery under different thermal runaway states. Specifically, as... Figure 7 As shown, the measurement method provided in this embodiment includes the following steps:

[0110] I. Debugging Phase:

[0111] S1: Install the battery to be tested on the battery clamp in the combustion chamber and seal the combustion chamber.

[0112] S2: Replace the gas inside the test container with background gas to form a stable and uniform gas convection environment, while controlling the gas flow rate in the flue.

[0113] S3: Use detection instruments or sensors to continuously monitor environmental parameters at various points in the combustion chamber and flue, and monitor the electrical parameters of the battery.

[0114] This step uses a VOC monitor and a gas analyzer to monitor the composition and concentration of flue gas, and a first thermocouple sensor to monitor the flue gas temperature. The collected environmental parameters include: combustion chamber sound pressure, instantaneous combustion chamber pressure, flue gas temperature, flue gas velocity, and the composition and concentration of flue gas.

[0115] II. Actual Measurement Phase

[0116] S4: According to the preset measurement task, one or more operations such as heating, squeezing, puncturing, and short circuit are performed to induce thermal runaway of the battery under test.

[0117] S5: Combine the sound pressure measurement data in the combustion chamber with the execution time of heating, squeezing, puncture or short circuit operations to determine the moment when thermal runaway of the battery under test occurs.

[0118] S6: Based on the precise response time of each detection instrument or sensor, the detection data is divided into the pre-thermal runaway stage and the post-thermal runaway stage.

[0119] During the sampling window period, the smoke particles and flue gas in the flue are sampled using a sampling device; the sampling window period refers to the time period during which the early flue gas generated by battery thermal runaway flows through the sampling device.

[0120] Specifically, the precise response time of the VOC monitor in this step is:

[0121]

[0122] In the above formula, t VOC s1 is the initial response time of the VOC monitor; s2 is the distance between the VOC monitor and the current stabilizing tube; f is the wind speed 10cm behind the current stabilizing tube under thermal runaway conditions of the battery under test.

[0123] The precise response time of the gas analyzer is:

[0124]

[0125] In the above formula, t gas s1 is the initial response time of the gas analyzer; s2 is the distance between the gas analyzer and the flow stabilizing tube; d is the diameter of the sampling tube in the gas analyzer; l is the length of the sampling tube in the gas analyzer; and Q is the flow rate value corresponding to the unit suction force of the gas analyzer.

[0126] The precise response time of the first thermocouple sensor is:

[0127]

[0128] In the above formula, t T s is the initial response time of the thermocouple; s3 is the distance between the first thermocouple sensor and the flow regulator.

[0129] S7: After obtaining the required test data, stop the ventilation to the combustion chamber, extinguish and cool the battery under test until the risk of battery explosion is eliminated.

[0130] S8: Perform offline detection on smoke particles and smoke samples obtained by the sampling device.

[0131] S9: By combining the process data of the pre- and post-thermal runaway stages obtained from the online detection process with the experimental data from the offline detection, the early smoke characteristics of the battery under test in the thermal runaway state are analyzed.

[0132] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A battery thermal runaway early smoke signature test platform, characterized in that, It is used for measuring the corresponding early smoke characteristics of the battery under different triggering conditions causing thermal runaway state; The early smoke characteristic test platform comprises: A test container comprising a combustion chamber and a flue; a battery clamp is arranged in the center of the combustion chamber; a gas inlet is arranged at the bottom of the combustion chamber, and a smoke collecting hood in an inverted funnel shape is arranged at the top of the combustion chamber, and a gas outlet at the top of the smoke collecting hood is communicated with a horizontally arranged flue; a flow stabilizing pipe is arranged at the interface between the combustion chamber and the flue, and a plurality of through holes for mounting devices are arranged on the outer wall of the flue; An air flow organization system for introducing background gas into the test container and forming a gas convection environment in which the background gas enters from the bottom of the combustion chamber, vertically rises downward of the battery clamp and is finally discharged along the outlet of the end section of the flue; A wind speed sensor is arranged at a position 10 cm behind the flow stabilizing pipe in the flue; An acoustic pressure sensor is arranged in the combustion chamber and is used for measuring noise information of the battery thermal runaway process; A gas pressure sensor is arranged in the combustion chamber and is used for measuring state data of the instantaneous gas pressure in the battery thermal runaway process; A thermal runaway triggering mechanism is arranged at the battery clamp, and the thermal runaway triggering mechanism comprises a needle piercing actuator, a pressing actuator and a heating device, which are respectively used for needle piercing, pressing and heating operations on the battery to be tested; A flue gas online analysis assembly comprising a first thermocouple sensor, a gas analyzer and a VOC monitor; the instruments in the flue gas online analysis assembly are arranged in the through holes on the outer wall of the flue, and the detection elements are inserted into the flue; the first thermocouple sensor is located at the side of the front end of the flue closest to the flow stabilizing pipe, and the gas analyzer and the VOC monitor are located at the side opposite to the first thermocouple sensor; A sampling device comprising a smoke particle sampling device and a flue gas sampling device; the instruments in the sampling device are arranged in the through holes on the outer wall of the flue and are located close to the end of the flue; An electrical measurement assembly is arranged in the battery clamp; the electrical measurement assembly is electrically connected with the battery to be measured through electrode sheets, is used for simulating the charging, discharging and natural state of the battery to be measured, and obtains the electrical parameters of the battery in the measurement process; the electrical measurement assembly is also used for simulating the short circuit fault of the battery; An upper computer electrically connected with the airflow organization system, the wind speed sensor, the sound pressure sensor, the air pressure sensor, the out-of-control triggering mechanism, the online analysis mechanism, the sampling device and the electrical measurement component; the upper computer is respectively used for:

1. controlling the airflow organization system to generate a uniform convection background gas environment in the combustion chamber that meets the preset condition, and ensuring that the measured value of the wind speed sensor under the initial state is 0.2±0.02 m / s; 2. controlling the out-of-control triggering mechanism or the electrical measurement component to trigger the battery thermal runaway to be tested according to the test task, and determining the triggering time of the thermal runaway in combination with the sampling data of the sound pressure sensor; 3. acquiring the real-time measurement data of the online monitoring component, the electrical measurement component and the air pressure sensor; 4. acquiring the sample detection result of the sample collected by the sampling device in the offline equipment; 5. comprehensively analyzing the sample data measured online and the detection result of the sample analyzed offline, and generating a complete battery thermal runaway early-stage smoke characteristic analysis report.

2. The battery thermal runaway early smoke signature test platform of claim 1, wherein: The test container further comprises at least one openable and closable sealing door and at least one transparent observation window; the inside of the test container is provided with a fireproof layer; Or A binocular camera with infrared and full-color cameras outside the observation window of the test container is arranged, and the binocular camera is used for recording image data in the thermal runaway experiment process.

3. The battery thermal runaway early smoke signature test platform of claim 2, wherein: The airflow organization system comprises: a high-pressure gas cylinder, a valve body, a gas flow meter, a centrifugal fan and a low-speed axial flow fan; the high-pressure gas cylinder contains the required background gas; the valve body is used for controlling the valve opening degree of the high-pressure gas cylinder discharging the background gas to the combustion chamber; the gas flow meter is installed at the positions of the gas inlet and the flue outlet of the combustion chamber, respectively, and is used for measuring the gas flow at the two positions; the centrifugal fan is installed at the end of the flue, and is used for discharging the gas in the combustion chamber from the test container; and the low-speed axial flow fan is installed at the position opposite to the battery clamp at the bottom of the combustion chamber, and is used for generating vertical upward lift.

4. The battery thermal runaway early smoke signature test platform of claim 3, wherein: The background gas is nitrogen, or a mixed gas obtained by mixing nitrogen and oxygen through a gas mixing valve at a molar ratio of 8:

2.

5. The battery thermal runaway early smoke signature test platform of claim 1, wherein: A second thermocouple sensor and a pressure gauge are further arranged on the battery clamp, the second thermocouple sensor is used for measuring the surface temperature of the battery to be tested in the thermal runaway process, and the pressure gauge is used for measuring the swelling pressure of the battery to be tested in the thermal runaway process.

6. The battery thermal runaway early smoke signature test platform of claim 1, wherein: The battery clamp comprises a mounting groove, an electric heating pipe in the heating device is installed at a position close to the bottom wall of the mounting groove inside the battery clamp, the extrusion actuator is installed directly above the battery clamp and can rotate relative to the battery clamp in the horizontal direction, the extrusion actuator adopts a downward feeding hydraulic mechanism, and after a steel needle is installed at the front end of the pressure head of the hydraulic mechanism, a needle pricking actuator required is formed.

7. The battery thermal runaway early smoke signature testing platform of claim 1, wherein: In the sampling device, the smoke particle sampling device adopts a copper mesh ultra-thin carbon film, and the smoke particle sample obtained is analyzed by a TEM electron microscope to obtain the composition, structural information and concentration information of the particulate matter contained in the flue gas. The flue gas sampling device comprises a sampling pump, a sampling tube and a vacuum air bag; the sampling pump extracts sample gas from the flue through the sampling tube and stores it in the vacuum air bag; the collected gas sample is analyzed by a gas chromatograph-mass spectrometer.

8. The battery thermal runaway early smoke signature testing platform of claim 1, wherein: The early flue gas characteristic test platform also comprises a safety system for spraying perfluorohexone or liquid nitrogen into the combustion chamber after the test to achieve fire prevention and cooling.

9. A method of measuring early smoke signatures of battery thermal runaway, the method comprising: The early flue gas characteristic test platform for battery thermal runaway as claimed in any one of claims 1-8 is used to analyze the early flue gas characteristics of the battery in different thermal runaway states; the measurement method comprises the following steps: I. Debugging phase: S1: install the battery to be tested on the battery clamp in the combustion chamber, and seal the combustion chamber; S2: replace the gas in the test container by background gas to form a stable and uniform gas convection environment, and control the gas flow rate in the flue; S3: continuously monitor the environmental parameters at various positions in the combustion chamber and the flue by using detection instruments or sensors, and monitor the electrical parameters of the battery; The environmental parameters include: combustion chamber sound pressure, combustion chamber instantaneous air pressure, flue gas temperature, flue air speed, flue gas composition and concentration; II. Measurement phase S4: according to the preset measurement task, one or any combination of heating, extrusion, needling and short circuit is used to trigger thermal runaway of the battery to be tested; S5: combine the sound pressure measurement data in the combustion chamber with the execution time of the heating, extrusion, needling or short circuit operation to comprehensively judge the thermal runaway occurrence time of the battery to be tested; S6: according to the accurate response time of each detection instrument or sensor, the detection data is divided into a pre-thermal runaway stage and a post-thermal runaway stage; and during the window period, the smoke particles and flue gas in the flue are sampled by the sampling device; The window period refers to the period when the early flue gas generated by the battery thermal runaway flows through the sampling device; S7: after obtaining the required test data, stop ventilating the combustion chamber, extinguish and cool the battery to be tested until the risk of battery explosion is eliminated; S8: off-line detect the smoke particles and flue gas samples obtained by the sampling device; S9: analyze the early flue gas characteristics of the battery to be tested in the thermal runaway state by combining the process data of the pre-thermal runaway stage and the post-thermal runaway stage obtained during the online detection process and the experimental data of the offline detection.

10. The method of measuring early smoke signatures of battery thermal runaway of claim 9, wherein: In step S3, a VOC monitor and a gas analyzer are used to cooperatively monitor the composition and concentration of the flue gas, and a first thermocouple sensor is used to monitor the flue gas temperature; In step S6, the accurate response time of the VOC monitor is: In the formula, t VOC is the initial response time of the VOC monitor; s1 is the distance between the VOC monitor and the constant current tube; f is the wind speed at 10 cm away from the constant current tube under the thermal runaway state of the battery to be tested; The accurate response time of the gas analyzer is: In the above formula, t gas is the initial response time of the gas analyzer; s2 is the distance between the gas analyzer and the steady flow tube; d is the tube diameter of the sampling tube in the gas analyzer, l is the length of the sampling tube in the gas analyzer, and Q is the flow value corresponding to the unit suction of the gas analyzer; The accurate response time of the first thermocouple sensor is: In the above formula, t T is the initial response time of the thermocouple; s3 is the distance between the first thermocouple sensor and the steady flow tube.

Images