An experimental device and experimental method for lithium battery thermal runaway propagation research

Abstract

The application discloses an experimental device and experimental method for lithium battery thermal runaway propagation research, which comprises an iron stand, cross beams, supports, fixing devices and heating devices, wherein the iron stand comprises a base plate and support rods symmetrically arranged on two sides above the base plate, a plurality of parallel cross beams are arranged between the two support rods, supports are arranged on the lower side of the cross beams, a sleeve is arranged on both ends of the cross beams and the supports and is sleeved on the support rods and is in sliding connection with the support rods; the middle part of the cross beams is provided with fixing devices for fixing lithium batteries; the middle part of the support is provided with a supporting circular plate, and the upper side of the supporting circular plate is provided with a heating device. The experimental device and experimental method for lithium battery thermal runaway propagation research adopt the above structure, provide an experimental device suitable for thermal runaway vertical propagation research of different models of lithium batteries, and carry out experimental research on the thermal runaway propagation mechanism of various lithium batteries in complex environments.

Description

Technical Field

[0001] This invention relates to the field of lithium battery thermal runaway technology, and in particular to an experimental apparatus and method for studying the propagation of lithium battery thermal runaway. Background Technology

[0002] With my country's goal of "peak carbon and carbon neutrality," promoting clean, low-carbon, safe, and efficient energy utilization is crucial. However, achieving this vision largely depends on lithium batteries, both in energy storage and electric vehicles. This is primarily due to the advantages of lithium batteries, such as high energy density, environmental friendliness, lack of memory effect, and long lifespan. Consequently, my country's lithium battery industry has developed rapidly in recent years, becoming the world's largest lithium battery consumer market for five consecutive years. In 2021, the global lithium battery market reached 545 GWh, while China's market size was approximately 324 GWh, accounting for a staggering 59.4% of the global market.

[0003] Thermal runaway is a major research focus in battery safety. Lithium-ion battery thermal runaway, triggered by various factors (overheating, overcharging, internal short circuits, collisions, etc.), results in a chain reaction phenomenon where the battery rapidly releases large amounts of heat and toxic gases, potentially leading to fires and explosions. Furthermore, thermal runaway in a single cell can spread to adjacent cells, causing even more severe thermal runaway (thermal runaway propagation) and potentially causing the entire battery module to spontaneously combust, posing a significant challenge to the widespread application of lithium-ion batteries.

[0004] In practical applications, lithium battery packs are arranged not only horizontally but also vertically during daily handling, storage (shelving), and transportation in vehicles such as new energy vehicles. While there is a wealth of research on the horizontal thermal runaway propagation of lithium batteries, including related experimental setups, research on the vertical thermal runaway propagation of multiple lithium batteries is scarce.

[0005] Furthermore, with the increasing application of lithium batteries in low-pressure environments such as high altitudes, aircraft, and spacecraft, the safety of lithium batteries under low pressure should be given sufficient attention. For example, in air transport, most cargo aircraft cabins have pressures below atmospheric pressure (e.g., 26 kPa at a cruising altitude of 10,000m, far lower than the 60-80 kPa of some pressurized passenger aircraft). Generally, lower pressure reduces ambient cooling, making ignition easier, while also weakening the flame and slowing the combustion and fire spread process. However, past research on thermal runaway of low-pressure single-cell batteries has found that due to insufficient oxygen supply, the heat release rate of battery fires decreases with increasing ambient pressure, and horizontal thermal runaway propagation under low pressure is also complex. Therefore, it is necessary to study the vertical propagation of lithium-ion battery thermal runaway to provide guidance for related engineering applications.

[0006] However, most current experimental studies on lithium battery thermal runaway primarily focus on single cells and multiple lithium batteries arranged horizontally or vertically side-by-side, employing external heating to induce thermal runaway. There is a lack of experimental setups suitable for studying the propagation of vertical thermal runaway in complex environments (low pressure, low oxygen, high temperature, low temperature, etc.). Therefore, there is an urgent need to provide an experimental setup for studying the propagation of thermal runaway in vertical lithium battery cells. Summary of the Invention

[0007] The purpose of this invention is to provide an experimental apparatus and method for studying the propagation of thermal runaway in lithium batteries, and to provide an experimental apparatus suitable for studying the vertical propagation of thermal runaway in different types of lithium batteries, so as to carry out experimental research on the propagation mechanism of thermal runaway in various lithium batteries under complex environments.

[0008] To achieve the above objectives, the present invention provides an experimental apparatus for studying the propagation of thermal runaway in lithium batteries, comprising an iron frame, crossbeams, supports, fixing devices, and heating devices. The iron frame includes a chassis and support rods symmetrically arranged on both sides above the chassis. Several parallel crossbeams are arranged between the two support rods. A support is provided on the lower side of the crossbeams. Both ends of the crossbeams and the support are provided with sleeves, which are fitted onto the support rods and slidably connected to the support rods.

[0009] The middle of each crossbeam is equipped with a fixing device for fixing lithium batteries. The middle of the fixing device is equipped with several adjacent connecting sleeves, and a temperature measuring device is slidably connected to the middle of the connecting sleeve.

[0010] The support plate is located in the middle of the bracket, and a heating device is located on the upper side of the support plate.

[0011] Preferably, the fixing device includes a fixing cylinder and a fixing bolt. The fixing cylinder has a mounting through hole in the middle, and the lithium battery passes through the mounting through hole. Several uniformly and symmetrically distributed fixing through holes are connected to the upper and lower sides of the mounting through hole. The fixing through holes are provided with internal threads. The fixing bolt is located on the outside of the fixing cylinder and is connected to the fixing through hole by threads.

[0012] Preferably, the heating device includes an insulating heating jacket and a heat-conducting pipe. The insulating heating jacket is a cylindrical structure with an opening on one side and an adjusting bolt at the opening. The heat-conducting pipe is located inside the insulating heating jacket, and the inner diameter of the heat-conducting pipe matches the outer diameter of the lithium battery.

[0013] Preferably, the inner circumferential surface of the heat pipe is in close contact with the outer circumferential surface of the lithium battery.

[0014] Preferably, the heat pipe is made of copper.

[0015] Preferably, one side of the ferrule has a threaded hole, and a ferrule fixing screw passes through the threaded hole. The ferrule fixing screw is connected to the threaded hole by threads.

[0016] Preferably, the temperature measuring device is a thermocouple.

[0017] Preferably, one side of the connecting sleeve is provided with a threaded hole two, and a fixing bolt two is inserted into the threaded hole two, and the fixing bolt two is connected to the threaded hole two by threads.

[0018] An experimental method for an experimental setup used in the study of thermal runaway propagation in lithium batteries includes the following steps:

[0019] (1) After assembling the above experimental device, fix the lithium battery in the fixing device, place the temperature measuring device in the connecting sleeve, so that the temperature measuring device extends into the fixing device and is in close contact with the lithium battery, and then fix the temperature measuring device by fixing bolt two.

[0020] (2) By adjusting the position of the connection between the sleeve and the support rod, the distance between the two adjacent crossbeams is adjusted, and the distance between the two experimental batteries is controlled to be 2-4mm.

[0021] (3) Select a heat pipe according to the model of the lithium battery, put the negative electrode of the lower lithium battery into the heat pipe, then put the heat pipe into the insulating heating sleeve, tighten the adjusting bolt, and make the insulating heating sleeve, heat pipe and lithium battery fit tightly.

[0022] (4) Check whether the lithium battery and temperature measuring device are securely fixed, and whether the temperature measuring device is connected to the I-7018 data acquisition module;

[0023] (5) Place the experimental device with the above connection above on the balance. A fireproof plate is provided between the balance and the experimental device. The balance and the I-7018 data acquisition module are connected to the PC computer through RS485 and RS232 communication interfaces respectively for data acquisition.

[0024] (6) Use a flue gas analyzer to record the changes in O2 / CO / CO2 concentration, use a camera to photograph the experimental process, and after the pre-experiment inspection is completed, turn on the heating device that triggers the thermal runaway of the lithium battery and turn on the data acquisition system at the same time until the end of the experiment, and record the data.

[0025] The beneficial effects of this invention are:

[0026] (1) The lithium battery thermal runaway vertical propagation experimental device of the present invention improves the previous lithium battery thermal runaway experiment by using high temperature tape to stick the thermocouple to the surface of the experimental lithium battery. The connection sleeve and the fixing bolt are used to facilitate the extension and retraction of the temperature measuring device. It can make the probe of the temperature measuring device more easily attached to the surface of the lithium battery, and the average value method is used to obtain a more accurate characteristic temperature of lithium battery thermal runaway.

[0027] (2) The lithium battery thermal runaway vertical propagation experimental device of the present invention can change the distance between the upper and lower batteries and the battery type according to the experimental requirements, and is suitable for conducting experimental research on the propagation of lithium battery thermal runaway under various environmental conditions in more complex environments (low pressure and low oxygen, high temperature and low temperature, etc.).

[0028] (3) The lithium battery thermal runaway propagation experiment of the present invention can change the experimental environment conditions, clarify the influence characteristics of pressure, ambient temperature, battery charge state and spacing on the vertical propagation of lithium battery thermal runaway, and analyze and obtain the critical criteria for lithium battery thermal runaway propagation; combined with theoretical analysis, a prediction model for whether thermal runaway propagation occurs (time) of multiple factors such as coupled pressure, ambient temperature and spacing is established, in order to provide guidance for the safe transportation and application of lithium batteries.

[0029] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of an experimental apparatus for studying the propagation of thermal runaway in lithium batteries according to the present invention;

[0031] Figure 2 This is a schematic diagram of a fixing device for an experimental apparatus used in the study of thermal runaway propagation in lithium batteries according to the present invention;

[0032] Figure 3 This is a cross-sectional schematic diagram of the fixing device of an experimental apparatus for studying the propagation of thermal runaway in lithium batteries according to the present invention.

[0033] Figure 4 This is a schematic diagram of a connecting sleeve for an experimental device used in the study of thermal runaway propagation in lithium batteries according to the present invention;

[0034] Figure 5 This is a schematic diagram of the heating device of an experimental apparatus for studying the propagation of thermal runaway in lithium batteries according to the present invention;

[0035] Figure 6 This is a schematic diagram of an insulating heating jacket, an experimental device for studying the propagation of thermal runaway in lithium batteries according to the present invention.

[0036] Figure label:

[0037] 1. Iron frame; 101. Chassis; 102. Support rod; 2. Crossbeam; 3. Bracket; 4. Fixing device; 401. Fixing cylinder; 402. Fixing bolt one; 403. Mounting through hole; 404. Fixing through hole; 5. Heating device; 501. Insulating heating jacket; 502. Heat conducting pipe; 503. Adjusting bolt; 6. Sleeve; 7. Connecting sleeve; 8. Temperature measuring device; 9. Supporting circular plate; 10. Sleeve fixing screw; 11. Fixing bolt two; 12. Lithium battery. Detailed Implementation

[0038] The present invention will be further described below with reference to the embodiments. Unless otherwise specified, all chemicals and reagents used in the embodiments are commercially available.

[0039] Example

[0040] Please see Figures 1 to 6 As shown in the figure, this invention provides an experimental apparatus for studying the propagation of thermal runaway in lithium batteries, including an iron frame 1, crossbeams 2, supports 3, a fixing device 4, and a heating device 5. The iron frame 1 includes a base 101 and support rods 102 symmetrically arranged on both sides above the base 101. The base 101 and the support rods 102 cooperate to improve the stability of the overall device's center of gravity during the thermal runaway experiment of the lithium battery 12. Several parallel crossbeams 2 are arranged between the two support rods 102. Supports 3 are provided on the lower side of the crossbeams 2. Both ends of the crossbeams 2 and the supports 3 are provided with retaining sleeves 6. The retaining sleeves 6 are fitted onto the support rods 102 and slidably connected to them. By adjusting the position of the retaining sleeves 6 connected to the support rods 102, the crossbeams 2 and supports 3 can be moved, facilitating the adjustment of the height position of the lithium battery 12 during the experiment. The sleeve 6 has a threaded hole on one side, and a sleeve fixing screw 10 is inserted into the threaded hole. The sleeve fixing screw 10 is connected to the threaded hole by threads. By tightening the sleeve fixing screw 10, the sleeve fixing screw 10 passes through the threaded hole and abuts against the support rod 102, thereby fixing the sleeve 6 and making it firmly connected to the support rod 102.

[0041] Each crossbeam 2 has a fixing device 4 for fixing the lithium battery 12 in the middle. The fixing device 4 includes a fixing cylinder 401 and a fixing bolt 402. The fixing cylinder 401 has a mounting through hole 403 in the middle, and the lithium battery 12 passes through the mounting through hole 403. Several evenly and symmetrically distributed fixing through holes 404 are connected to the upper and lower sides of the mounting through hole 403. The fixing through holes 404 have internal threads. The fixing bolt 402 is located on the outside of the fixing cylinder 401 and is connected to the fixing through hole 404 by threads. After the lithium battery 12 is placed in the mounting through hole 403, the fixing bolt 402 is tightened so that the fixing bolt 402 abuts against the lithium battery 12, thereby fixing the lithium battery 12 firmly.

[0042] The fixing device 4 has several adjacent connecting sleeves 7 in its middle. Each connecting sleeve 7 has a through hole that intersects with the mounting through hole 403. A temperature measuring device 8 is slidably connected inside the through hole of the connecting sleeve 7. The temperature measuring device 8 can be a thermocouple. Specifically, three connecting sleeves 7 are arranged at the same height on the side center of the fixing device 4 to cooperate with thermocouples. The temperature of the lithium battery 12 is measured by the three thermocouples, and the average value is taken to calculate the thermal runaway characteristic temperature of the lithium battery 12, thereby characterizing the propagation rate between the vertical lithium batteries 12.

[0043] A threaded hole 2 is provided on one side of the connecting sleeve 7, and a fixing bolt 2 11 passes through the threaded hole 2, with the fixing bolt 2 11 connected to the threaded hole 2 by threads. A thermocouple is inserted into the connecting sleeve 7, extending into the fixing device 4 and abutting against the lithium battery 12, so that the thermocouple probe is in close contact with the surface of the lithium battery 12, allowing for more accurate measurement of the battery surface temperature during thermal runaway. Tightening the fixing bolt 2 11, which passes through the threaded hole 2 and abuts against the thermocouple, secures the thermocouple firmly. Loosening the fixing bolt 2 11 allows the thermocouple to slide within the connecting sleeve 7, enabling the thermocouple to extend and retract, facilitating control of the thermocouple's extension and retraction length, and ensuring close contact between the thermocouple and the battery surface, thus aiding in more accurate recording of the lithium battery 12 surface temperature during experiments.

[0044] A supporting circular plate 9 is located in the middle of the support frame 3, and a heating device 5 is located on the upper side of the supporting circular plate 9 to induce thermal runaway of the lithium battery 12 during the experiment. The heating device 5 includes an insulating heating sleeve 501 and a heat-conducting pipe 502. The insulating heating sleeve 501 is a cylindrical structure with an opening on one side, and an adjusting bolt 503 is provided at the opening. By tightening or loosening the adjusting bolt 503, the diameter of the insulating heating sleeve 501 can be adjusted, thus making it suitable for different types of lithium batteries 12. The heat-conducting pipe 502 is located inside the insulating heating sleeve 501, and the heat-conducting pipe 502 can be made of copper. The inner diameter of the heat-conducting pipe 502 matches the outer diameter of the lithium battery 12, and the inner circumferential surface of the heat-conducting pipe 502 is in close contact with the outer circumferential surface of the lithium battery 12. The model of the heat pipe 502 is matched with the model of the lithium battery 12. By setting the heat pipe 502, the stability of the connection between the lithium battery 12 and the heating device 5 is ensured. At the same time, the surface of the lithium battery 12 can be fully in contact with the external heat source during the experiment. With the help of the heat pipe 502 with good thermal conductivity, the thermal energy that triggers the thermal runaway of the lithium battery 12 is provided evenly.

[0045] An experimental method for an experimental setup used in the study of thermal runaway propagation in lithium batteries includes the following steps:

[0046] (1) After assembling the above experimental device, fix the lithium battery in the fixing device. The lithium battery can be of type 18650 or type 21700. Fix the lithium battery firmly with fixing bolt one. Place the temperature measuring device in the connecting sleeve so that the temperature measuring device extends into the fixing device and is in close contact with the surface of the lithium battery. Then fix the temperature measuring device with fixing bolt two.

[0047] (2) By adjusting the position of the connection between the sleeve and the support rod, the distance between the two adjacent crossbeams is adjusted, and the distance between the two experimental batteries is controlled to be 2-4mm.

[0048] (3) Select a heat pipe according to the model of the lithium battery, put the negative electrode of the lower lithium battery into the heat pipe, then put the heat pipe into the insulating heating sleeve, tighten the adjusting bolt, and make the insulating heating sleeve, heat pipe and lithium battery fit tightly.

[0049] (4) Check whether the lithium battery and temperature measuring device are securely fixed, and connect the temperature measuring device to the I-7018 data acquisition module;

[0050] (5) Place the experimental device with the above connection above on the balance. A fireproof plate is provided between the balance and the experimental device. The balance and the I-7018 data acquisition module are connected to the PC computer through RS485 and RS232 communication interfaces respectively for data acquisition.

[0051] (6) Use a flue gas analyzer to record the changes in O2 / CO / CO2 concentration, use a camera to photograph the experimental process, and after the pre-experiment inspection is completed, turn on the heating device that triggers the thermal runaway of the lithium battery and turn on the data acquisition system at the same time until the end of the experiment, and record the data.

[0052] Therefore, the present invention employs the above-mentioned experimental apparatus and method for studying the propagation of thermal runaway in lithium batteries, which can change environmental conditions, such as in a low-pressure, low-oxygen environment, to conduct experiments on the vertical thermal runaway propagation of lithium-ion batteries under low pressure, study the influence of battery state of charge and spacing on the vertical propagation of thermal runaway in lithium batteries under low pressure, reveal the influence mechanism of low pressure on the vertical propagation of thermal runaway in lithium batteries, and provide theoretical guidance for the safe storage and transportation of lithium batteries.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An experimental apparatus for studying the propagation of thermal runaway in lithium batteries, characterized in that: It includes an iron frame, crossbeams, supports, fixing devices, and heating devices. The iron frame includes a chassis and support rods symmetrically arranged on both sides above the chassis. Several parallel crossbeams are arranged between the two support rods. Supports are provided on the lower side of the crossbeams. Both ends of the crossbeams and supports are provided with sleeves, which are fitted onto the support rods and slidably connected to the support rods. The middle of each crossbeam is equipped with a fixing device for fixing lithium batteries. The middle of the fixing device is equipped with several adjacent connecting sleeves, and a temperature measuring device is slidably connected to the middle of the connecting sleeve. A supporting circular plate is provided in the middle of the bracket, and a heating device is provided on the upper side of the supporting circular plate; The fixing device includes a fixing cylinder and a fixing bolt. The fixing cylinder has a mounting through hole in the middle, and the lithium battery passes through the mounting through hole. Several evenly and symmetrically distributed fixing through holes are connected to the upper and lower sides of the mounting through hole. The fixing through holes are provided with internal threads. The fixing bolt is located on the outside of the fixing cylinder and is connected to the fixing through hole by threads. The heating device includes an insulating heating jacket and a heat-conducting pipe. The insulating heating jacket is a cylindrical structure with an opening on one side and an adjusting bolt at the opening. The heat-conducting pipe is located inside the insulating heating jacket, and the inner diameter of the heat-conducting pipe matches the outer diameter of the lithium battery. One side of the connecting sleeve is provided with a threaded hole two, and a fixing bolt two is inserted into the threaded hole two. The fixing bolt two is connected to the threaded hole two by threads. The temperature measuring device extends into the fixing device and is in close contact with the lithium battery. Then the temperature measuring device is fixed by the fixing bolt two.

2. The experimental apparatus for studying the propagation of thermal runaway in lithium batteries according to claim 1, characterized in that: The inner circumferential surface of the heat pipe is in close contact with the outer circumferential surface of the lithium battery.

3. The experimental apparatus for studying the propagation of thermal runaway in lithium batteries according to claim 1, characterized in that: One side of the ferrule has a threaded hole, and a ferrule fixing screw passes through the threaded hole. The ferrule fixing screw is connected to the threaded hole by threads.

4. The experimental apparatus for studying the propagation of thermal runaway in lithium batteries according to claim 1, characterized in that: The temperature measuring device is a thermocouple.

5. An experimental method for an experimental apparatus for studying the propagation of thermal runaway in lithium batteries as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) After assembling the above experimental device, fix the lithium battery in the fixing device, place the temperature measuring device in the connecting sleeve, so that the temperature measuring device extends into the fixing device and is in close contact with the lithium battery, and then fix the temperature measuring device by fixing bolt two. (2) By adjusting the position of the connection between the sleeve and the support rod, the distance between the two adjacent crossbeams is adjusted, and the distance between the two experimental batteries is controlled to be 2-4mm. (3) Select a heat pipe according to the model of the lithium battery, put the negative electrode of the lower lithium battery into the heat pipe, then put the heat pipe into the insulating heating sleeve, tighten the adjusting bolt, and make the insulating heating sleeve, heat pipe and lithium battery fit tightly. (4) Check whether the lithium battery and temperature measuring device are securely fixed, and whether the temperature measuring device is connected to the I-7018 data acquisition module; (5) Place the experimental device with the above connection above on the balance. A fireproof plate is provided between the balance and the experimental device. The balance and the I-7018 data acquisition module are connected to the PC computer through RS485 and RS232 communication interfaces respectively for data acquisition. (6) Use a flue gas analyzer to record the changes in O2 / CO / CO2 concentration, use a camera to photograph the experimental process, and after the pre-experiment inspection is completed, turn on the heating device that triggers the thermal runaway of the lithium battery and turn on the data acquisition system at the same time until the end of the experiment, and record the data.

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