Multifunctional lithium battery thermodynamic experiment device

Abstract

A multifunctional lithium battery thermodynamic experiment device comprises a battery cell pressure container with a closed internal space. A battery weighing table, an electrolyte weighing table, a battery placing frame and a needling mechanism are arranged in the pressure container, the battery placing frame is arranged on the battery weighing table and is provided with a battery placing area capable of placing a plurality of battery cells to be detected, and the battery placing area is provided with a battery cell heating piece; a quartz glass groove arranged on the electrolyte weighing table is arranged below the battery placing area; the needling mechanism is arranged on the side surface of the battery placing rack; the needling mechanism comprises a hydraulic prop, a connecting rod and a needling head, the needling head faces the battery placing area and is connected with the output end of the hydraulic prop through the connecting rod, and a temperature thermocouple is arranged in the needling head. The experimental device provided by the utility model has the advantages of multiple purposes, flexible functions, diversified assembly, wide application range, reasonable structural design, compact spatial arrangement and simple test method operation.

Description

Technical Field

[0001] The utility model relates to the field of thermal runaway and safety technology of lithium batteries, and in particular to a multifunctional lithium battery thermodynamics experimental device. Background Art

[0002] In the context of achieving the "dual carbon" goal, lithium-ion batteries are widely used in the field of energy storage due to their advantages such as high operating voltage, long cycle life, and no memory. They are the main carrier of electrochemical energy storage technology in the new energy revolution. However, lithium-ion batteries will spontaneously react and generate heat under conditions such as overheating, overcharging, and collision, leading to thermal runaway and even explosion. In actual scene applications, lithium-ion batteries appear in the form of arrays. The energy generated by the thermal runaway of a single battery will spread to the surrounding area, which may trigger a thermal runaway chain reaction in adjacent batteries, resulting in more serious fire consequences. Therefore, it is of great practical significance to carry out research on the propagation law of thermal runaway of lithium-ion batteries and its suppression methods, master the behavioral characteristics and hazard parameters of thermal runaway of lithium-ion battery packs, determine the key factors of thermal runaway propagation, reveal the propagation law of thermal runaway of lithium-ion batteries, select appropriate isolation and suppression methods, and reduce the fire hazard of thermal runaway propagation of battery packs, which is of great practical significance for promoting the safe and sustainable development of energy storage.

[0003] There is a lack of technical research on lithium battery thermodynamics experiments, which leads to the inability to accurately simulate the thermal runaway process of lithium batteries. Most of the thermal runaway experimental studies of lithium-ion batteries are for single lithium batteries, and most of them are heating to cause the lithium battery to run away. The gas analysis process generated by thermal runaway is cumbersome and prone to errors. At the same time, there is no corresponding device support for the heat generation and heat transfer characteristics experiment of the thermal runaway propagation process of lithium batteries under different gas environments, the thermal runaway propagation inhibition experiment, and the electrolyte leakage characteristics experiment of the thermal runaway process. In the actual experimental process, it was found that some lithium batteries did not burn after thermal runaway. It is difficult to grasp the thermal runaway propagation law of lithium-ion batteries, and it is impossible to evaluate the risk factors of lithium batteries in the thermal runaway process under various environments and the inhibitory effect of different barrier materials on thermal runaway propagation. It cannot provide reliable data basis for the development of lithium battery safety technology.

[0004] Based on this, it is necessary to design a multifunctional lithium battery thermodynamic experimental device to provide support for lithium battery experiments. Utility Model Content

[0005] Based on this, the utility model provides a multifunctional lithium battery thermodynamics experimental device to solve the problems that the existing lithium battery thermodynamics experimental device cannot achieve comprehensive performance testing and cannot meet the requirements of batch battery cell testing.

[0006] To achieve the above-mentioned purpose, the utility model provides a multifunctional lithium battery thermodynamics experimental device, which includes a battery pressure container with a closed internal space;

[0007] A battery weighing platform, an electrolyte weighing platform, a battery placement rack and a needling mechanism are arranged in the pressure vessel. The battery placement rack is arranged on the battery weighing platform. The battery placement rack is provided with a battery placement area for placing multiple battery cells to be tested. The battery placement area is provided with a battery cell heating plate. A quartz glass tank for collecting electrolyte placed on the electrolyte weighing platform is provided below the battery placement area. The needling mechanism is arranged on the side of the battery placement rack; the needling mechanism includes a hydraulic support, a connecting rod and a needling head. The needling head faces the battery placement area and is connected to the output end of the hydraulic support through the connecting rod. A temperature measuring thermocouple is arranged in the needling head; a jet fire total temperature sensor and a jet fire total heat sensor are provided on the battery placement rack above the battery placement area;

[0008] The pressure vessel is provided with a plurality of external interfaces, including a vacuum interface, a nitrogen filling interface, a gas monitoring interface and an electric spark interface. The vacuum interface is connected to an air pump through a pipeline, the nitrogen filling interface is connected to a nitrogen supply source through a pipeline, and the gas monitoring interface is connected to a Fourier gas monitor through a pipeline. An ignition electrode is provided in the pressure vessel, and the wire of the ignition electrode is connected to an electric spark generator located outside the pressure vessel through the electric spark interface.

[0009] The pressure vessel is equipped with a pressure sensor and an electrochemical oxygen sensor for detecting the internal environment; the pressure vessel is provided with an observation window, a camera is installed on the outside of the observation window, and the camera is used to sample the image of the internal space of the battery pressure vessel through the observation window.

[0010] As a further preferred technical solution of the utility model, the battery placement rack includes a bottom plate, a middle hollow plate and an upper hollow plate which are arranged in sequence from bottom to top, and the bottom plate, the middle hollow plate and the upper hollow plate are connected by multiple vertical poles. The battery placement rack is placed on the battery weighing platform through the lower ends of the vertical poles. The battery placement area is between the bottom plate and the middle hollow plate, and the quartz glass groove is arranged below the bottom plate. A jet fire total temperature sensor mounting plate is provided between the middle hollow plate and the upper hollow plate, and the jet fire total temperature sensor mounting plate is used to install a jet fire total temperature sensor. The hollow area of ​​the upper hollow plate is provided with a jet fire total heat sensor mounting plate, and the jet fire total heat sensor mounting plate is used to install a jet fire total heat sensor.

[0011] As a further preferred technical solution of the utility model, the vertical rod is a threaded rod, the installation heights of the bottom plate, the middle hollow plate and the upper hollow plate on the threaded rod are all adjustable, and the threaded rod is equipped with a nut for height adjustment.

[0012] As a further preferred technical solution of the utility model, the acupuncture mechanism further includes a transversely arranged guide rail, the hydraulic support can be transversely slidably arranged on the guide rail, and the hydraulic support slides transversely along the guide rail to adjust the position of the acupuncture head.

[0013] As a further preferred technical solution of the utility model, a charging and discharging device is also provided outside the pressure vessel, and the charging and discharging device extends into the pressure vessel through a wire, and the charging and discharging device is used to charge and discharge the battery cells placed in the battery placement area.

[0014] As a further preferred technical solution of the present utility model, the pressure sensor is arranged on the pressure container through a connecting pipe, and a valve is provided on the connecting pipe between the pressure container and the pressure sensor.

[0015] As a further preferred technical solution of the present utility model, the external interface also includes a fire extinguishing agent interface located at the top of the pressure vessel, and the fire extinguishing agent interface is used to connect a fire extinguisher.

[0016] As a further preferred technical solution of the present utility model, the external interface also includes a reserved gas interface.

[0017] As a further preferred technical solution of the utility model, an explosion-proof fan and a lighting fixture are also provided on the top of the pressure vessel.

[0018] As a further preferred technical solution of the utility model, it also includes a control system, which includes a computer and a PLC that are communicatively connected to each other, the camera is electrically connected to the computer, and the battery weighing platform, electrolyte weighing platform, temperature measuring thermocouple, pressure sensor, electrochemical oxygen sensor, jet fire total temperature sensor and jet fire total heat sensor are electrically connected.

[0019] The multifunctional lithium battery thermodynamics experimental device of the utility model adopts the above technical scheme to achieve the following beneficial effects:

[0020] (1) The experimental device is multi-functional, flexible in function, diverse in assembly, has a wide range of applications, reasonable structural design, compact space layout, and simple experimental method operation.

[0021] (2) The utility model adopts a battery cell pressure container which is combined with a vacuum interface and a nitrogen filling interface to simulate different pressure and gas environments, and realizes a variety of thermal runaway triggering modes through an external stimulus application device, so as to study the thermal runaway law of lithium batteries under the coupling of multiple factors and the influence of different pressures and gas environments on thermal runaway, and can more accurately simulate the thermal runaway process, providing a reliable basis for lithium battery safety technology.

[0022] (3) The utility model can realize multiple thermal runaway trigger modes, can adjust the thermal runaway trigger position according to different needs, and install a thermocouple inside the acupuncture head of the acupuncture device to measure the temperature change inside the battery. In addition, an electrolyte collection device is designed to collect and measure the electrolyte leaked during thermal runaway in real time, which is conducive to analyzing the leakage characteristics of the battery during thermal runaway.

[0023] (4) The utility model can realize online monitoring of gas during thermal runaway of the battery. By connecting the Fourier gas monitor to the cabin, the gas changes during the thermal runaway process can be analyzed in real time. There is no need to collect and analyze the gas, which can greatly reduce the error generation.

[0024] (5) The utility model fully considers the experimental requirements of lithium battery arrangement, and can adjust the battery spacing according to different experimental settings, which is conducive to simulating the impact of different actual conditions on the battery thermal runaway propagation process. At the same time, the integrated test bench can adjust the distance between the battery and the sensor according to the jet fire injection height, greatly reducing the error of the environment and the sensor installation position on the test, and has the advantage of being highly flexible and adjustable.

[0025] (6) The ignition electrode designed in the utility model can realize ignition from different positions according to needs, making up for the deficiency of traditional devices that do not burn after battery thermal runaway. It is beneficial to study the heat generation and heat transfer characteristics of battery thermal runaway, and provides a basis for building a three-dimensional heat transfer coupled battery thermal runaway numerical model.

[0026] (7) The utility model is designed with a fire extinguishing agent interface, which greatly improves the safety of the experiment and can be used to evaluate the fire extinguishing effects of different fire extinguishing agents on lithium battery fires, thereby providing assistance for actual battery fire rescue. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0028] Figure 1 This is a schematic diagram of the structure of a multifunctional lithium battery thermodynamic experimental device;

[0029] Figure 2 It is a schematic diagram of the battery pressure vessel and its internal structure;

[0030] Figure 3 It is a structural schematic diagram of a battery placement rack;

[0031] Figure 4 It is a structural schematic diagram of the acupuncture head.

[0032] In the figure: 1-bottom plate; 2-middle hollow plate; 3-upper hollow plate; 4-vertical pole; 5-jet fire total temperature sensor mounting plate; 6-jet fire total heat sensor mounting plate; 7-vacuum pump; 8-safety valve; 9-pressure sensor; 10-vacuum interface; 11-nitrogen filling interface; 12-reserved gas interface; 13-electrochemical oxygen sensor; 14-nitrogen bottle; 15-hydraulic support; 16-connecting rod; 17-acupuncture head; 18-charging and discharging device; 19-battery weighing platform; 20- Flexible insulation film; 21-battery core heating plate; 22-battery placement area; 23-Fourier gas detector; 24-computer; 25-PLC; 26-observation window; 27-jet fire total temperature sensor; 28-jet fire total heat sensor; 29-fire extinguishing agent interface; 30-spark generator; 31-camera; 33-spark interface; 34-slide rail; 35-quartz glass tank; 36-electrolyte weighing table: 37-explosion-proof fan; 38-temperature measuring thermocouple; 39-lighting fixture.

[0033] The purpose, features and advantages of the present invention will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods. The terms such as "upper", "lower", "left", "right", "middle" and "one" used in the preferred embodiments are only used to facilitate the description, and are not used to limit the scope of the implementation of the present invention. The changes or adjustments in their relative relationships shall also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0035] like Figure 1-4 As shown, the utility model provides a multifunctional lithium battery thermodynamic experimental device, including a battery pressure vessel with a closed internal space, the battery pressure vessel is made of stainless steel, and an engineering pressure safety valve 8 is arranged on the cabin to ensure that the cabin can be depressurized in time when the pressure is too high, so as to ensure the safety of the test; the cabin is filled with aluminum silicate insulation cotton for insulation, with a thickness of 50mm, and the insulation effect is good, which can maintain the temperature inside the cabin constant. The battery cell placement port of the battery pressure vessel is opened and closed by a movable door, which is easy to operate, and a lighting fixture 39 is arranged on the top of the internal warehouse for lighting.

[0036] The pressure vessel is provided with a battery weighing platform 19, an electrolyte weighing platform 36, a battery placement rack and a needle puncture mechanism. The battery placement rack is placed on the battery weighing platform 19. The battery placement rack is provided with a battery placement area 22 for placing multiple cells to be tested. A quartz glass tank 35 for collecting electrolyte is provided below the battery placement area 22 and is placed on the electrolyte weighing platform 36. The battery weighing is used to weigh the cells placed in the battery placement area 22, and the electrolyte weighing platform 36 is used to weigh the electrolyte collected in the quartz glass tank 35, which flows out to the quartz glass tank 35 after the cells are broken.

[0037] The puncture mechanism is used to apply external force to destroy the battery cell shell, and it is arranged on the side of the battery placement rack. The puncture mechanism includes a hydraulic support 15, a connecting rod 16 and a puncture head 17. The puncture head 17 faces the battery placement area 22 and is connected to the output end of the hydraulic support 15 through the connecting rod 16. A temperature measuring thermocouple 38 is arranged in the puncture head 17. The hydraulic support 15 drives the puncture head 17 to move so as to pierce the battery cell shell, thereby achieving the purpose of destroying the battery cell by external force. At the same time, the temperature is detected by the temperature measuring thermocouple 38 when piercing the battery cell. The puncture mechanism also includes a transversely arranged guide rail, and the hydraulic support 15 can be arranged on the guide rail in a transverse sliding manner. The hydraulic support 15 slides transversely along the guide rail to adjust the position of the puncture head 17, so that different batteries or different parts of the battery can be punctured and destroyed.

[0038] The pressure vessel is provided with a plurality of external interfaces, including a vacuum extraction interface 10 , a nitrogen filling interface 11 , a gas monitoring interface and an electric spark interface 33 .

[0039] Wherein: the vacuum interface 10 is connected to the vacuum pump 7 through a pipeline, and the nitrogen filling interface 11 is connected to the nitrogen source through a pipeline, and the nitrogen source can be a high-pressure nitrogen bottle 14. The vacuum interface 10 and the nitrogen filling interface 11 adopt the same structural design, which includes a valve body with a solenoid valve and / or a manual valve, and the valve body is connected to the pressure vessel, and the valve body is connected to the corresponding pipeline through a gas pipeline quick interface.

[0040] The gas monitoring interface is connected to a Fourier gas monitor through a pipeline. The Fourier gas monitor is placed below the battery pressure vessel. An explosion-proof fan 37 for air stirring is installed inside the battery pressure vessel to make the internal gas evenly distributed, so as to assist the Fourier gas monitor in gas monitoring and reduce the error.

[0041] An ignition electrode is provided in the pressure vessel, and the wire of the ignition electrode is connected to the spark generator 30 located outside the pressure vessel through the spark interface 33. The ignition electrode is equivalent to a spark plug, and the spark generator 30 controls the ignition electrode to electrically ignite the battery placement area 22. In practical applications, the position of the ignition electrode can be adjusted according to experimental requirements, which is not limited here. A jet fire total temperature sensor 27 and a jet fire total heat sensor 28 are provided on the battery placement rack above the battery placement area 22. The ignition electrode generates a jet fire during the ignition process, and the jet fire total temperature sensor 27 and the jet fire total heat sensor 28 perform corresponding detection.

[0042] Preferably, the external interface also includes a fire extinguishing agent interface 29 located at the top of the pressure vessel, and the fire extinguishing agent interface 29 is used to connect a fire extinguisher, which can be used to extinguish the thermal runaway combustion of the lithium battery, or to test the extinguishing and suppression effects of different fire extinguishing agents on the thermal runaway combustion of the lithium battery. The external interface also includes a reserved gas interface 12, which can be connected to other types of gas supply sources to meet different experimental requirements.

[0043] The pressure vessel is installed with a pressure sensor 9 and an electrochemical oxygen sensor 13 for detecting the internal environment. The pressure sensor 9 is arranged on the pressure vessel through a connecting pipe, and a valve is provided on the connecting pipe between the pressure vessel and the pressure sensor 9, and the valve is a manual ball valve or / and a solenoid valve. The electrochemical oxygen sensor 13 monitors the oxygen inside the pressure vessel, and a manual ball valve or / and a solenoid valve is installed between the electrochemical oxygen sensor 13 and the pressure vessel. During the process of exhausting and filling with nitrogen, the inspection data of the electrochemical oxygen sensor 13 is valid. During the thermal runaway test of the battery cell, the valve between the electrochemical oxygen sensor 13 and the pressure vessel is automatically closed to protect the oxygen sensor.

[0044] An observation window 26 is provided on the pressure vessel, and the observation window 26 is composed of explosion-proof glass installed on a flange window, so as to keep the internal space sealed during the test and facilitate the tester to observe the internal situation. A camera 31 is installed on the outside of the observation window 26, and the camera 31 is used to sample the image of the internal space of the battery pressure vessel through the observation window 26.

[0045] The device also includes a control system, which includes a computer 24 and a PLC 25 that are communicatively connected to each other, a camera 31 that is electrically connected to the computer 24, and a battery weighing platform 19, an electrolyte weighing platform 36, a temperature measuring thermocouple 38, a pressure sensor 9, an electrochemical oxygen sensor 13, a jet fire total temperature sensor 27 and a jet fire total heat sensor 28 that are electrically connected.

[0046] A charging and discharging device 18 is also provided outside the pressure vessel. The charging and discharging device 18 extends into the pressure vessel through a wire. The charging and discharging device 18 is used to charge and discharge the battery cells placed in the battery placement area 22 .

[0047] In a specific embodiment, the battery placement rack includes a bottom plate 1, a middle hollow plate 2 and an upper hollow plate 3 which are arranged in sequence from bottom to top, the bottom plate 1, the middle hollow plate 2 and the upper hollow plate 3 are connected by a plurality of vertical poles 4, the battery placement rack is placed on the battery weighing platform 19 through the lower end of the vertical pole 4, the bottom plate 1 and the middle hollow plate 2 are between the battery placement area 22, the quartz glass groove 35 is arranged below the bottom plate 1, a jet fire total temperature sensor mounting plate 5 is arranged between the middle hollow plate 2 and the upper hollow plate 3, the jet fire total temperature sensor mounting plate 5 is used to install the jet fire total temperature sensor 27, the hollow area of ​​the upper hollow plate 3 is provided with a jet fire total heat sensor mounting plate 6, the jet fire total heat sensor mounting plate 6 is used to install the jet fire total heat sensor 28. Preferably, the vertical pole 4 is a threaded rod, a nut is arranged on the threaded rod, and the bottom plate 1, the middle hollow plate 2 and the upper hollow plate 3 can all be adjusted by nuts to the installation height on the threaded rod.

[0048] Specifically, the bottom plate 1, the middle hollow plate 2 and the upper hollow plate 3 are all made of pure steel plates. The bottom plate 1 mainly serves to place the battery pack. It has four through holes at its four corners. A cell heating plate 21 is provided on the bottom plate 1 to trigger thermal runaway of the battery. A flexible insulation film 20 is provided between the cell heating plate 21 and the bottom plate 1. The hollow size of the middle hollow plate 2 is slightly smaller than the upper end face size of the battery pack. Its function is to suppress and fix the battery pack, and the jet fire spraying area is not affected. The hollow size of the upper hollow plate 3 is the same as that of the middle hollow plate 2. In addition, a conductive heat flux sensor is placed between the two cells of the battery pack. Through conductive heat monitoring, the heat transfer state and heat loss degree between single batteries can be studied.

[0049] Test application example 1:

[0050] The experimental method of thermal runaway of lithium battery driven by multi-stimulus coupling under different environments is implemented as follows:

[0051] Step 1: Select the required external experimental device according to the experimental requirements and prepare the lithium battery to be tested in advance;

[0052] Step 2: Open the movable door of the battery pressure vessel, adjust the bottom plate and the middle hollow plate by turning the nuts, and then fix the experimental lithium battery in the battery placement area of ​​the battery placement rack, and adjust the distance between the battery and the jet fire total temperature sensor and the jet fire total heat sensor measuring point. It is best if the measuring point is about 3cm to 5cm away from the upper end surface of the battery. Make specific adjustments based on experimental requirements.

[0053] Step 3: Install the battery surface temperature sensor on the surface of the experimental lithium battery and cover it tightly with a flexible thermal insulation film to create a relatively closed and insulated environment for the thermal runaway process of the lithium battery. Close the movable door to seal the battery pressure vessel. At the same time, use a camera to record the entire thermal runaway process in the cabin.

[0054] Step 4: Power on, turn on the pressure sensor, and use the vacuum pump to evacuate the gas in the battery pressure vessel until the pressure sensor displays a number of -100kPa. According to the needs, inject 1 atmosphere of inert gas or air into the battery pressure vessel through the reserved gas interface until the pressure sensor displays a number that stabilizes at 0kPa, then turn off the air intake switch. Different pressure values ​​can be adjusted according to the specific needs of the experiment. When testing thermal runaway experiments under inert gas, the open cycle inflation function can also be used. The operator needs to turn on the nitrogen filling and vacuum function buttons in manual mode, respectively, and cooperate with the electrochemical oxygen sensor to observe the concentration changes of the electrochemical oxygen sensor in real time. When the oxygen concentration is ≤1%, manually turn off the two function buttons.

[0055] Step five, according to the needs, use different external stimulation application devices to trigger thermal runaway of the lithium battery. The first method is to energize the battery cell heating plate to heat the battery. The second method is to move the acupuncture device along the slide rail to the required position and use the controlled hydraulic support to propel it. Different acupuncture heads can be replaced according to different needs; the third method can apply stimulation factors such as battery short circuit, continuous charging and discharging, or battery charge control through battery short circuit and charge and discharge connection lines.

[0056] Step six, under the application of multi-factor coupling stimulation, the lithium battery undergoes thermal runaway, and the explosion-proof fan is turned on to stir the internal gas so that the gas generated during the thermal runaway process is evenly distributed inside the pressure vessel. The gas inside the container is monitored online by a fully automatic Fourier gas monitor, and the pressure, temperature and lithium battery quality data during the thermal runaway process are monitored by a pressure sensor, a battery surface temperature sensor, a temperature measuring thermocouple carried by the acupuncture head, a weighing system (battery weighing platform, electrolyte weighing platform), etc. The entire thermal runaway process is monitored, and the start and thermal runaway gas release time T1 and the end time T2 are recorded. The entire thermal runaway gas release time is recorded as T, T=T1-T2. At the same time, the electrolyte collection device is used to collect the electrolyte leaked during the thermal runaway process, and the supporting weighing device is used to monitor the quality of the leaked electrolyte for reference in analyzing the electrolyte leakage characteristics during the thermal runaway process, and the temperature-time, pressure-time, lithium battery quality-time and thermal runaway gas concentration-time data on the computer are saved.

[0057] Step seven, wait until the surface temperature of the lithium battery drops to room temperature, use the cyclic charging function, turn on the nitrogen filling and vacuum function buttons in manual mode respectively, completely discharge the thermal runaway flammable and toxic gases in the battery pressure vessel, open the movable door, and use compressed air to blow and clean the inside of the battery pressure vessel.

[0058] Test application example 2:

[0059] The experimental scheme for analyzing the heat generation and heat transfer characteristics of lithium battery thermal runaway is as follows:

[0060] Step 1: Select an external experimental device according to the experimental requirements and prepare the lithium battery pack for the experiment in advance;

[0061] Step 2: Open the movable door of the battery pressure vessel, connect the experimental lithium battery pack in series or in parallel, adjust the bottom plate and the middle hollow plate by screwing the nuts, fix the battery in the battery placement area in the battery placement rack, and adjust the distance between the battery and the jet fire total temperature sensor and the jet fire total heat sensor measuring point. It is best if the measuring point is about 3 cm to 5 cm away from the upper end surface of the battery. Make specific adjustments based on experimental requirements.

[0062] Step 3: Install conductive heat flux sensors and temperature sensors between the experimental lithium battery packs and cover them tightly with flexible thermal insulation film to create a relatively closed and insulated environment for the thermal runaway process of the lithium battery. Close the movable door to seal the battery pressure vessel. At the same time, use a camera to record the entire thermal runaway process in the cabin.

[0063] Step 4: Power on, turn on the pressure sensor, and use the vacuum pump to evacuate the gas in the battery pressure vessel until the pressure sensor displays a number of -100kPa. Then, according to the needs, inject 1 atmosphere of air into the battery pressure vessel through the reserved gas interface until the pressure sensor displays a number that stabilizes at 0kPa, and then turn off the air intake switch. Alternatively, the open cycle inflation function can be used during the experiment. The operator needs to turn on the air inflation and vacuum function buttons in manual mode to ensure that there is sufficient oxygen in the container to ensure the propagation of thermal runaway.

[0064] Step five: Use a puncture device to trigger thermal runaway of the lithium battery, and adjust the position of the puncture device along the slide rail according to the experimental settings.

[0065] Step six, under the application of multi-factor coupled stimulation, the lithium battery undergoes thermal runaway, and the temperature changes inside the battery are monitored by the temperature measuring thermocouple inside the puncture head. The heat conduction between batteries and the temperature changes between individual batteries are monitored by the conductive heat flow sensor and the temperature sensor, and the internal battery temperature-time, each battery temperature-time and the heat conduction data between batteries are saved on the computer.

[0066] Step 7: After thermal runaway, if no flame appears, ignite it with an ignition device, and monitor the heat flux and temperature through the jet fire total temperature sensor and the jet fire total heat sensor. Through the measured data and according to the calculation methods of heat conduction, heat convection and heat radiation, quantify the heat generation and heat transfer process of thermal runaway of the battery pack, and provide a basis for building a three-dimensional coupled thermal runaway numerical model of lithium battery packs and revealing the thermal runaway propagation process of the battery pack.

[0067] Step eight, turn off the circulating inflation function, connect the fire extinguishing agent through the fire extinguishing agent interface to extinguish the open flame. You can set different fire extinguishing agents to test the suppression effect of different fire extinguishing agents on lithium battery fires. Use the circulating inflation function, turn on the nitrogen filling and vacuum function buttons in manual mode respectively, and completely discharge the thermal runaway flammable and toxic gases in the battery pressure vessel. Open the movable door and use compressed air to blow and clean the inside of the battery pressure vessel.

[0068] Test application example three:

[0069] The specific implementation steps of the experiment to inhibit the propagation of thermal runaway of lithium batteries are as follows:

[0070] Step 1: Select an external experimental device according to the experimental requirements and prepare the lithium battery pack for the experiment in advance;

[0071] Step 2: Open the movable door of the battery pressure vessel, connect the experimental lithium battery pack in series or in parallel, set barrier materials between the two battery cells, and adjust the bottom plate and the middle hollow plate by screwing the nuts, fix the battery in the battery placement area in the battery placement rack, and adjust the distance between the battery and the jet fire total temperature sensor and the jet fire total heat sensor measuring point. It is best if the measuring point is about 3cm to 5cm away from the upper end surface of the battery, and make specific adjustments based on experimental requirements.

[0072] Step 3: Install conductive heat flux sensors and temperature sensors on the opposite sides of the two batteries in the experimental lithium battery pack, and use a flexible thermal insulation film to tightly cover the lower side of the lithium battery clamping compartment to create a relatively closed and insulated environment for the thermal runaway process of the lithium battery. Install the integrated test bench on the cabin, and then close the movable door to seal the battery pressure vessel. At the same time, use a camera to record the entire thermal runaway process in the cabin.

[0073] Step 4: Turn on the power, turn on the pressure sensor, and use the vacuum pump to evacuate the gas in the battery cell pressure vessel until the pressure sensor displays a number of -100kPa. Stop, and inject 1 atmosphere of inert gas or air into the battery cell pressure vessel as needed, and turn off the air inlet switch when the pressure sensor displays a number that stabilizes at 0kPa.

[0074] Step five: According to the needs, use different external stimulus application devices to trigger thermal runaway of the lithium battery.

[0075] Step six, under the application of multi-factor coupled stimulation, the lithium battery undergoes thermal runaway, and the heat conduction between the batteries and the temperature changes between the batteries are monitored through the conduction heat flux sensor and the temperature sensor, and the battery internal temperature-time, each battery temperature-time and the heat conduction data between batteries are saved on the computer.

[0076] Step seven: Evaluate the barrier material based on the measured data and whether the batteries adjacent to the thermal runaway battery have thermal runaway.

[0077] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A multifunctional lithium battery thermodynamics experimental device, characterized in that: A battery cell pressure vessel including a sealed internal space; A battery weighing platform, an electrolyte weighing platform, a battery placement rack and a needling mechanism are arranged in the pressure vessel. The battery placement rack is arranged on the battery weighing platform. The battery placement rack is provided with a battery placement area for placing multiple battery cells to be tested. The battery placement area is provided with a battery cell heating plate. A quartz glass tank for collecting electrolyte placed on the electrolyte weighing platform is provided below the battery placement area. The needling mechanism is arranged on the side of the battery placement rack; the needling mechanism includes a hydraulic support, a connecting rod and a needling head. The needling head faces the battery placement area and is connected to the output end of the hydraulic support through the connecting rod. A temperature measuring thermocouple is arranged in the needling head; a jet fire total temperature sensor and a jet fire total heat sensor are provided on the battery placement rack above the battery placement area; The pressure vessel is provided with a plurality of external interfaces, including a vacuum interface, a nitrogen filling interface, a gas monitoring interface and an electric spark interface. The vacuum interface is connected to an air pump through a pipeline, the nitrogen filling interface is connected to a nitrogen supply source through a pipeline, and the gas monitoring interface is connected to a Fourier gas monitor through a pipeline. An ignition electrode is provided in the pressure vessel, and the wire of the ignition electrode is connected to an electric spark generator located outside the pressure vessel through the electric spark interface. The pressure vessel is equipped with a pressure sensor and an electrochemical oxygen sensor for detecting the internal environment; the pressure vessel is provided with an observation window, a camera is installed on the outside of the observation window, and the camera is used to sample the image of the internal space of the battery pressure vessel through the observation window.

2. The multifunctional lithium battery thermodynamic experimental device according to claim 1, characterized in that: The battery placement rack includes a bottom plate, a middle hollow plate and an upper hollow plate which are arranged in sequence from bottom to top, and the bottom plate, the middle hollow plate and the upper hollow plate are connected by multiple vertical poles. The battery placement rack is placed on the battery weighing platform through the lower ends of the vertical poles. The battery placement area is between the bottom plate and the middle hollow plate. The quartz glass groove is arranged below the bottom plate. A jet fire total temperature sensor mounting plate is provided between the middle hollow plate and the upper hollow plate. The jet fire total temperature sensor mounting plate is used to install a jet fire total temperature sensor. A jet fire total heat sensor mounting plate is provided in the hollow area of ​​the upper hollow plate. The jet fire total heat sensor mounting plate is used to install a jet fire total heat sensor.

3. The multifunctional lithium battery thermodynamic experimental device according to claim 2, characterized in that: The vertical rod is a threaded rod, and the installation heights of the bottom plate, the middle hollow plate and the upper hollow plate on the threaded rod are all adjustable. The threaded rod is equipped with a nut for height adjustment.

4. The multifunctional lithium battery thermodynamic experimental device according to claim 1, characterized in that: The acupuncture mechanism further comprises a transversely arranged guide rail, on which the hydraulic support can be transversely slidably arranged, and the hydraulic support slides transversely along the guide rail to adjust the position of the acupuncture head.

5. The multifunctional lithium battery thermodynamics experimental device according to claim 1, characterized in that: A charging and discharging device is also provided outside the pressure container. The charging and discharging device extends into the pressure container through a wire, and is used to charge and discharge the battery cells placed in the battery placement area.

6. The multifunctional lithium battery thermodynamics experimental device according to claim 1, characterized in that: The pressure sensor is arranged on the pressure container via a connecting pipe, and a valve is arranged on the connecting pipe between the pressure container and the pressure sensor.

7. The multifunctional lithium battery thermodynamics experimental device according to claim 1, characterized in that: The external interface also includes a fire extinguishing agent interface located at the top of the pressure container, and the fire extinguishing agent interface is used to connect a fire extinguisher.

8. The multifunctional lithium battery thermodynamics experimental device according to claim 1, characterized in that: The external interface also includes a reserved gas interface.

9. The multifunctional lithium battery thermodynamics experimental device according to claim 1, characterized in that: An explosion-proof fan and a lighting fixture are also provided on the top of the pressure vessel.

10. The multifunctional lithium battery thermodynamics experimental device according to any one of claims 1 to 9, characterized in that: It also includes a control system, which includes a computer and a PLC that are communicatively connected to each other, the camera is electrically connected to the computer, and the battery weighing platform, electrolyte weighing platform, temperature measuring thermocouple, pressure sensor, electrochemical oxygen sensor, jet fire total temperature sensor and jet fire total heat sensor are electrically connected.

Images