Multi-window lithium ion battery mechanical abuse gas analysis and optical diagnosis device

Abstract

The invention discloses a multi-window lithium ion battery mechanical abuse gas analysis and optical diagnosis device in the technical field of lithium ion battery thermal safety. Comprising a constant volume bomb, a battery clamp, a battery support, a constant volume bomb sealing cover, a constant volume bomb sealing flange, a loading mechanism, a motor control system, a gas analysis and exhaust system, an optical window system, a schlieren optical diagnosis system, an infrared temperature measurement optical diagnosis system and a particle image velocity measurement system. According to the invention, a mechanical abuse experiment can be carried out on a single battery or a small module, and the loading position, direction, speed, time and depth are adjustable. Power is transmitted between a stepping motor and a driven piece of the loading mechanism through a magnetic coupling, and movement of a pricking needle / extrusion head is not interfered by a sealing piece. According to the invention, air pressure, total gas production amount and gas components in the thermal runaway process can be measured, and a density field, a temperature field, a velocity field, a flow field transient phenomenon, a flame form and a flame propagation process of thermal runaway exhaust and a thermal propagation process of a small module can be obtained at the same time.

Description

Technical Field

[0001] The present invention relates to a testing device in the field of lithium-ion battery thermal safety technology, in particular to a multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnosis device capable of performing mechanical abuse experiments on battery cells or small modules. Background Art

[0002] Lithium-ion batteries are widely used in new energy vehicles due to their relatively high energy density, good cycle performance, and fast response speed. However, when a vehicle collides, if the battery cells are not adequately protected, thermal runaway problems will occur under mechanical abuse conditions. During thermal runaway, the internal temperature and pressure of the lithium battery rise sharply. When the internal pressure reaches a certain value, the safety valve opens, and flammable gases produced by side reactions are ejected. After mixing with air, they may burn and explode, seriously threatening the safety of the passengers in the vehicle. Therefore, in order to conduct in-depth research on thermal runaway prevention and control measures under mechanical abuse conditions, it is necessary to design a sealed battery mechanical abuse gas analysis device to obtain important experimental data such as gas pressure, total gas production, and gas composition in a confined space under mechanical abuse conditions. Existing related sealed mechanical abuse gas analysis devices are generally small in volume and can only be used to conduct experiments on battery cells. They cannot be used to study the heat spread phenomenon of small modules.

[0003] Common forms of mechanical abuse testing include extrusion and needle penetration. Extrusion tests examine the failure mode of batteries after compression and deformation, similar to the intrusive loads experienced by the battery system after a new energy vehicle collision. Needle penetration tests can be considered extreme extrusion tests with extremely small tip diameters. Existing experimental devices lack overload protection for the driving components of the loading mechanism. If the needle / extrusion head becomes stuck in the battery, the driving components can be easily damaged. Loading position, speed, depth, and direction are often difficult to adjust and control.

[0004] Chinese patent application publication number CN 115586449 A discloses a lithium-ion battery thermal runaway gas production testing system. The external puncture unit's first steel needle sequentially passes through a compression cap, an adjustment pad, and a high-temperature-resistant conical sealing sleeve before entering the sealed tank. This system can measure the composition of gas produced by lithium-ion batteries during thermal runaway under mechanical abuse conditions. However, the movement of the first steel needle is easily disturbed by the conical sealing gasket, and the seal is prone to failure under the high-pressure environment after thermal runaway.

[0005] When a battery safety valve opens, electrolyte droplets, electrolyte vapor, and solid particles are ejected as side reactions produce gases, creating a complex multiphase flow process. Heat released by the ejected materials accounts for 70-80% of the thermal runaway process. Thermal radiation from flue gases and the sputtering of hot particles can also lead to disordered and random thermal runaway propagation. Therefore, to gain a deeper understanding of the thermal propagation process, develop and validate relevant numerical simulation models, and improve the design of cell safety valves and battery pack safety systems, it is necessary to analyze the gas composition and obtain transient flow field phenomena such as density, temperature, velocity, and shock waves, as well as flame morphology and propagation during the thermal runaway exhaust and combustion processes. Traditional contact measurement methods such as thermocouples and pitot tubes suffer from significant time lag, slow response, and suboptimal spatial resolution, making them inadequate for thermal runaway scenarios characterized by high air velocities, high turbulence intensity, and large temperature gradients. To obtain accurate, reliable, and intuitive experimental data, it is necessary to combine optical diagnostic methods such as schlieren, infrared temperature measurement, and particle image velocimetry.

[0006] Existing mechanical abuse test devices for related seals generally have no or only one optical window, making it difficult to coordinate or simultaneously implement optical diagnostic methods such as schlieren, infrared temperature measurement, and particle image velocimetry. Optical images are mainly evaluated qualitatively, making it difficult to conduct comprehensive, accurate, and reliable quantitative analysis.

[0007] Based on this, how to innovatively design a sealed, multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnostic device is a technical challenge that needs to be urgently solved in this field. Summary of the Invention

[0008] In response to the deficiencies in the prior art, the present invention proposes a multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnostic device. The operation of the loading mechanism is not interfered with by the seals, and it can withstand high pressure (1MPa) during thermal runaway. The loading position, direction, speed, and depth are flexibly controllable. The enclosed space has a large volume, and can measure the gas production pressure of lithium-ion battery cells or small modules under mechanical abuse conditions. The total gas production can then be calculated, the gas collected, and the components analyzed. The device has multiple windows with different positions and directions, and can simultaneously perform optical diagnoses such as schlieren, infrared temperature measurement, and particle image velocimetry to obtain transient flow field phenomena such as density field, temperature field, velocity field, and shock wave of thermal runaway exhaust, flame morphology and propagation process, and heat spread process of small modules.

[0009] The present invention is achieved through the following technical solutions: the present invention includes a constant volume bomb, a battery clamp, a battery holder, a constant volume bomb sealing cover, a constant volume bomb sealing flange, a loading mechanism, a motor control system, a gas analysis and exhaust system, a quartz glass optical window system, and a sapphire glass optical window system; the constant volume bomb is a hollow cube, and three pairs of orthogonal holes are opened on its front, back, left, right, and upper and lower outer walls, and each through hole is provided with a mounting groove; the front, rear, upper, left, and right through holes are used to arrange the sapphire glass optical window system or the quartz glass optical window system or the loading mechanism, and the lower through hole is used to arrange the constant volume bomb sealing cover; the constant volume bomb sealing cover is arranged in the through hole mounting groove on the lower side of the constant volume bomb, and the constant volume bomb sealing flange is arranged On the outside of the constant volume bomb sealing cover and connected to the wall of the constant volume bomb through bolts; the battery clamp and battery support are located inside the constant volume bomb for fixing battery cells or small modules, and the battery clamp and battery support are connected to the constant volume bomb sealing cover on the lower side of the constant volume bomb through bolts; the loading mechanism includes a loading mechanism sealing cover, a loading mechanism sealing flange, a stepper motor, a motor support steel sleeve, a magnetic coupling, a ball screw mechanism, a needle / extrusion head bracket, and a needle / extrusion head. The loading mechanism sealing cover is arranged in the through-hole mounting groove of the constant volume bomb, the loading mechanism sealing flange is arranged on the outside of the loading mechanism sealing cover and connected to the wall of the constant volume bomb through bolts, and the motor support steel sleeve and the loading mechanism sealing cover are connected together by bolts. The stepper motor is connected to the motor support steel sleeve by bolts, the output shaft of the stepper motor is connected to the magnetic coupling, the magnetic coupling is connected to the ball screw mechanism, the ball screw mechanism is connected to the puncture needle / extrusion head, and the puncture needle / extrusion head is arranged on the puncture needle / extrusion head bracket; the motor control system includes a motor power supply, a motor controller, and a computer. The motor control system is arranged outside the constant volume bomb, and the motor controller is connected to the motor power supply, computer, and stepper motor through a wiring harness; the gas analysis and exhaust system includes a barometer, a sampling valve, an exhaust valve, a gas chromatograph, a gas pipeline, and a vacuum pump. The barometer, sampling valve, and exhaust valve are all installed on the constant volume bomb, and the gas chromatograph is connected to the sampling valve through a gas pipeline. The vacuum pump is connected to the exhaust valve through a gas pipeline; the sapphire glass optical window system includes a large optical window flange, a small optical window flange, and sapphire glass. The large optical window flange is connected to the wall of the constant volume bomb through bolts. The sapphire glass is arranged between the large optical window flange and the small optical window flange. The large optical window flange and the small optical window flange are connected together by bolts; the quartz glass optical window system includes a large optical window flange, a small optical window flange, and quartz glass. The large optical window flange is connected to the wall of the constant volume bomb through bolts. The quartz glass is arranged between the large optical window flange and the small optical window flange. The large optical window flange and the small optical window flange are connected together by bolts;

[0010] Furthermore, the present invention also includes a Schlieren optical diagnostic system, which includes a point light source, a first plane mirror, a first concave mirror, a second concave mirror, a second plane mirror, a light knife, and a high-speed camera. A quartz glass optical window system is arranged in the front and rear through holes of the constant volume bomb, and a loading mechanism is arranged in the left through hole of the constant volume bomb. The point light source, the first plane mirror, and the first concave mirror are arranged at the rear side of the outside of the constant volume bomb, and the second concave mirror, the second plane mirror, the light knife, and the high-speed camera are arranged at the front side of the outside of the constant volume bomb; light is emitted from the point light source, passes through the first plane mirror, the first concave mirror, the rear quartz glass optical window system, the inside of the constant volume bomb, the front quartz glass optical window system, the second concave mirror, the second plane mirror, and the light knife, and is captured by the high-speed camera.

[0011] Furthermore, the present invention also includes an infrared temperature measurement optical diagnostic system, which includes a first high-speed infrared thermal imager and a second high-speed infrared thermal imager. Sapphire glass optical window systems are arranged on the upper and right through holes of the constant volume bomb, and a loading mechanism is arranged on the left through hole of the constant volume bomb. The first high-speed infrared thermal imager and the second high-speed infrared thermal imager are both arranged outside the constant volume bomb, the first high-speed infrared thermal imager faces the right sapphire glass optical window system, and the second high-speed infrared thermal imager faces the upper sapphire glass optical window system.

[0012] Furthermore, the present invention also includes a particle image velocimetry system, which includes a laser, a cylindrical mirror, a high-speed camera, and a synchronous controller. A quartz glass optical window system is arranged in the upper, front, and rear through holes of the constant volume bomb, and a loading mechanism is arranged in the left through hole of the constant volume bomb. The laser, cylindrical mirror, high-speed camera, and synchronous controller are all arranged outside the constant volume bomb, with the laser facing the upper quartz glass optical window system, the cylindrical mirror is arranged between the laser and the quartz glass optical window system, and multiple high-speed cameras are respectively arranged outside the front and rear quartz glass optical window systems. The laser and the high-speed camera are connected to the synchronous controller through a wiring harness.

[0013] Furthermore, in the present invention, the constant volume bomb sealing cover is a solid steel cylinder, and an O-ring is used to seal the constant volume bomb sealing cover and the constant volume bomb.

[0014] Furthermore, in the present invention, the magnetic coupling includes an outer rotor, an isolation sleeve, and an inner rotor, and keyways are provided on the outer rotor and the inner rotor of the magnetic coupling; the output shaft of the stepper motor is connected to the outer rotor of the magnetic coupling through a key; one end of the screw passes through the center hole of the loading mechanism sealing cover and is connected to the inner rotor of the magnetic coupling through a key.

[0015] Furthermore, in the present invention, the ball screw mechanism includes a screw, a screw nut, a screw nut seat, a screw fixing seat, a screw support seat, a screw support connecting plate, and a linear guide rail. The screw is supported by the screw fixing seat and the screw support seat, and the screw fixing seat is fixed to the inner surface of the loading mechanism sealing cover by bolts; the screw fixing seat and the screw support seat are respectively connected to the screw support connecting plate by bolts to achieve fixation of the screw support seat.

[0016] Furthermore, in the present invention, there is a hole on both sides of the screw fixing seat, screw nut, screw nut seat and screw support seat for installing a linear guide rail, and the linear guide rail constrains the screw nut and screw nut seat to perform linear motion.

[0017] Furthermore, in the present invention, the needle / extrusion head bracket is fixed to the screw nut seat by bolts, a plurality of bolt holes are opened on the end surface of the needle / extrusion head bracket, and the tail of the needle / extrusion head is threaded.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] First, the internal volume of the constant volume bomb is relatively large, and the experimental object can be a battery cell or a small module.

[0020] Second, a magnetic coupling connects the driving and driven components of the loading mechanism. This seal is achieved through the magnetic coupling's sealing sleeve, ensuring a secure seal without interfering with the movement of the needle / extrusion head. This ensures a secure seal. If the needle / extrusion head becomes stuck in the battery, the motor will not be damaged, providing overload protection.

[0021] Third, the loading direction can be changed by changing the installation position of the loading mechanism to achieve axial loading or lateral loading of the battery.

[0022] Fourth, the needle / extrusion head can be flexibly replaced according to experimental requirements, and the installation position can be adjusted to change the loading position. By controlling the motor speed and running time, the loading speed and depth can be flexibly controlled, enabling quasi-static mechanical loading experiments or dynamic mechanical loading experiments, as well as continuous or interrupted loading.

[0023] Fifth, the integral sealing of the constant volume bomb and loading mechanism can withstand the high temperatures and high pressures (1 MPa) encountered during thermal runaway experiments. This allows for measuring the gas pressure within a confined space after thermal runaway of a battery under mechanical abuse conditions, calculating the total amount of gas produced during thermal runaway, and collecting gas samples for component analysis. Simultaneously, zero to four sapphire glass or quartz glass optical window systems in different positions and orientations can be combined with optical diagnostic methods such as schlieren, infrared temperature measurement, and particle image velocimetry. Quantitative analysis of the optical images reveals transient flow field phenomena such as density, temperature, velocity, and shock waves during thermal runaway exhaust, as well as flame morphology and propagation, and the heat spread of small modules. This allows for comprehensive and quantitative observation and analysis of the external exhaust and combustion processes of thermally runaway batteries. The experimental data is crucial for developing and validating relevant numerical simulation models, developing battery thermal runaway safety measures, and improving the intrinsic safety of lithium-ion batteries.

[0024] Sixth, the loading mechanism, optical window, sealing cover and sealing flange installed on the constant volume bomb can be modularly disassembled and assembled, which is convenient and quick, making it easy to install other sensors inside the constant volume bomb and to clean the constant volume bomb after the experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the overall experimental device for side loading using a Schlieren optical diagnostic system and an infrared temperature measurement optical diagnostic system in an embodiment of the present invention;

[0026] Figure 2 Schematic diagram of the overall experimental setup for side loading using a particle image velocimetry system and an infrared temperature measurement optical diagnostic system in an embodiment of the present invention;

[0027] Figure 3 This is an overall cross-sectional view of the constant volume bomb, constant volume bomb sealing cover, constant volume bomb sealing flange, loading mechanism, sapphire glass optical window system, and quartz glass optical window system in an embodiment of the present invention;

[0028] Figure 4 A cross-sectional view of a constant volume bomb sealing cover and a constant volume bomb sealing flange in an embodiment of the present invention;

[0029] Figure 5 Schematic diagram of a loading mechanism in an embodiment of the present invention;

[0030] Figure 6 Schematic diagram of the sealing method of the loading mechanism in an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of axial loading in an embodiment of the present invention;

[0032] Figure 8 Schematic diagram of the sealing of a sapphire glass optical window system and a quartz glass optical window system in an embodiment of the present invention;

[0033] Figure 9 This is a flow chart of the experimental method in the embodiment of the present invention;

[0034] Figure 10 This is a flow chart of schlieren image contour extraction in an embodiment of the present invention;

[0035] In the figure, 1. battery clamp, 2. battery holder, 3. sapphire glass, 4. optical window large flange, 5. optical window small flange, 6. O-ring, 7. gasket, 8. constant volume spring, 9. constant volume spring sealing cover, 10. constant volume spring sealing flange, 11. stepper motor, 12. stepper motor output shaft, 13. magnetic coupling outer rotor, 14. key, 15. magnetic coupling isolation sleeve, 16. magnetic coupling inner rotor, 17. motor support steel sleeve, 18. loading mechanism sealing cover, 19. loading mechanism sealing flange, 20. screw, 21. screw nut, 22. screw nut seat, 23. screw fixing seat, 24. screw support seat, 25. screw support connecting plate, 26. linear guide, 27. needle / extrusion head bracket, 2 8. Needle / extrusion head, 29. Sampling valve, 30. Exhaust valve, 31. Barometer, 33. Gas chromatograph, 34. Vacuum pump, 35. Gas pipeline, 36. Motor controller, 37. Power supply, 38. Computer, 39. Point light source, 40. First plane mirror, 41. First concave mirror, 42. Second concave mirror, 43. Second plane mirror, 44. Light knife, 45. High-speed camera, 46. First high-speed infrared thermal imager, 47. Second high-speed infrared thermal imager, 48. Laser, 49. Cylindrical mirror, 50. Synchronous controller, 201. Quartz glass optical window system, 202. Loading mechanism, 203. Battery cell or small module, 204. Sapphire glass optical window system, 205. Quartz glass. DETAILED DESCRIPTION

[0036] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further explained below in conjunction with specific embodiments. The examples are only used to illustrate the present invention, but the present invention is not limited to these contents.

[0037] Example

[0038] like Figure 1 and Figure 2 As shown, the present invention includes a constant volume bomb 8, a battery clamp 1, a battery support 2, a constant volume bomb sealing cover 9, a constant volume bomb sealing flange 10, a loading mechanism, a motor control system, a gas analysis and exhaust system, a quartz glass optical window system, a sapphire glass optical window system, a schlieren optical diagnostic system, an infrared temperature measurement optical diagnostic system, and a particle image velocimetry system.

[0039] like Figure 1 、 Figure 2 and Figure 3 As shown, the constant volume bomb 8 is a hollow cube with three orthogonal holes on its front, back, left, right, and top and bottom outer walls, for a total of six openings. Each opening has a mounting slot surrounded by bolt holes. These, when fitted with an O-ring 6, can be used to install the constant volume bomb sealing cover 9, the constant volume bomb sealing flange 10, the loading mechanism 202, the quartz glass optical window system 201, and the sapphire glass optical window system 204. The battery clamp 1 and battery holder 2 are located inside the constant volume bomb 8; the motor control system is located outside the constant volume bomb 8 and connected to the stepper motor 11 in the loading mechanism 202; the gas analysis and exhaust system is connected to the interior of the constant volume bomb 8; the Schlieren optical diagnostic system and particle image velocimetry system are located outside the constant volume bomb 8 and installed in conjunction with the quartz glass optical window system 201; and the infrared optical diagnostic system is located outside the constant volume bomb 8 and installed in conjunction with the sapphire glass optical window system 204.

[0040] When the Schlieren optical diagnostic system is used, a quartz glass optical window system 201 is arranged in the front and rear through holes of the constant volume bomb 8, and a loading mechanism 202 is arranged in the left through hole of the constant volume bomb 8; when the infrared temperature measurement optical diagnostic system is used, a sapphire glass optical window system 204 is arranged in the upper and right through holes of the constant volume bomb 8, and a loading mechanism 202 is arranged in the left through hole of the constant volume bomb 8; when the particle image velocimetry system is used, a quartz glass optical window system 201 is arranged in the upper, front and rear through holes of the constant volume bomb 8, and a loading mechanism 202 is arranged in the left through hole of the constant volume bomb 8.

[0041] like Figure 3 As shown, the battery clamp 1 and the battery support 2 are connected to the constant volume spring sealing cover 9 on the bottom surface of the constant volume spring 8 by bolts, and are used to fix the battery cell or small module 203.

[0042] like Figure 4 As shown, the constant volume bomb sealing cover 9 and constant volume bomb sealing flange 10 are used to seal the opening of the constant volume bomb 8 without the optical window system. The constant volume bomb sealing cover 9 is a solid steel cylinder that can be placed in the installation groove of the constant volume bomb 8 opening. The constant volume bomb sealing cover 9 and the constant volume bomb 8 are sealed with an O-ring 6. The boss of the constant volume bomb sealing flange 10 can press the constant volume bomb sealing cover 9 into the installation groove. The constant volume bomb sealing flange 10 and the constant volume bomb 8 are connected by bolts.

[0043] like Figure 5 As shown, the loading mechanism includes a loading mechanism sealing cover 18, a loading mechanism sealing flange, a stepper motor 11, a motor support steel sleeve 17, a magnetic coupling, a ball screw mechanism, a needle / extrusion head bracket 27, a needle / extrusion head 28, bolts, and an O-ring. The magnetic coupling includes an outer rotor 13, an isolation sleeve 15, and an inner rotor 16. The ball screw mechanism includes a screw 20, a screw nut 21, a screw nut seat 22, a screw fixing seat 23, a screw support seat 24, a screw support connecting plate 25, and a linear guide rail 26.

[0044] The sealing method of the loading mechanism is as follows:

[0045] like Figure 6 As shown, the loading mechanism sealing cover 18 can be inserted into the mounting groove of the constant volume bomb 8. The loading mechanism sealing cover 18 and the constant volume bomb 8 are sealed with an O-ring 6. The boss of the loading mechanism sealing flange 19 can press the loading mechanism sealing cover 18 into the mounting groove. The loading mechanism sealing flange 19 and the constant volume bomb 8 are connected by bolts. The loading mechanism as a whole can be fixed to the constant volume bomb 8 by bolts.

[0046] like Figure 6 As shown, the stepper motor 11 is connected to the motor support steel sleeve 17 through bolts, and the motor support steel sleeve 17 is connected to the loading mechanism sealing cover 18 through bolts.

[0047] like Figure 6 As shown, keyways are provided on both the outer rotor 13 and the inner rotor 16 of the magnetic coupling. The stepper motor output shaft 12 is connected to the outer rotor 13 of the magnetic coupling via a key 14. One end of the lead screw 20 extends through the center hole of the loading mechanism sealing cover 18 and is connected to the inner rotor 16 of the magnetic coupling via a key 14.

[0048] like Figure 6 As shown, the magnetic coupling spacer sleeve 15 is bolted to the outer surface of the loading mechanism sealing cover 18. An O-ring 6 is used to seal the spacer sleeve 15 and the outer surface of the loading mechanism sealing cover 18, forming a sealed area. Within the sealed area, the magnetic coupling inner rotor 16 is connected to the lead screw 20.

[0049] The structure of the ball screw mechanism in the loading mechanism is as follows:

[0050] like Figure 5 As shown, the screw 20 is supported by a screw fixing seat 23 and a screw support seat 24. The screw fixing seat 23 is fixed to the inner surface of the loading mechanism sealing cover 18 by bolts. The screw fixing seat 23 and the screw support seat 24 are respectively connected to the screw support connecting plate 25 by bolts to fix the screw support seat 24.

[0051] like Figure 5 As shown, there is a hole on each side of the screw fixing seat 23, the screw nut 21, the screw nut seat 22, and the screw support seat 24 for installing a linear guide 26. The linear guide 26 constrains the screw nut 21 and the screw nut seat 22 to do linear motion.

[0052] like Figure 5As shown, the needle / extrusion head bracket 27 is fixed to the screw nut base 22 by bolts. A plurality of bolt holes are opened on the end surface of the needle / extrusion head bracket 27, and the tail end of the needle / extrusion head 28 is threaded. The needle / extrusion head 28 can be fixed to the appropriate position of the needle / extrusion head bracket 27 according to the experimental requirements, thereby adjusting the loading position according to the experimental requirements.

[0053] The loading mechanism works as follows:

[0054] like Figure 5 As shown, first, the stepper motor output shaft 12 drives the magnetic coupling outer rotor 13 to rotate via key 14. Second, the magnetic coupling outer rotor 13 drives the magnetic coupling inner rotor 16 to rotate through magnetic force. Next, the magnetic coupling inner rotor 16 drives the lead screw 20 to rotate. Finally, the ball screw mechanism converts rotary motion into linear motion. The lead screw nut 21 drives the lead screw nut holder 22 to move linearly along the linear guide 26. The needle / extrusion head 28 moves linearly along the needle / extrusion head bracket 27 fixed to the lead screw nut holder 22, achieving linear motion to load battery cells or small modules.

[0055] The loading mechanism can be installed at different positions of the constant volume bomb to adjust the loading direction. Figure 1 、 Figure 2 As shown in the figure, the loading mechanism can be installed on the side of the constant volume bomb to achieve side loading of battery cells or small modules. Figure 7 As shown, the loading mechanism can also be installed on the top surface of the constant volume bomb to achieve axial loading of the battery cell or small module.

[0056] like Figure 1 、 Figure 2 As shown, the motor control system includes a power supply 37, a motor controller 36 and a computer 38. The computer 38 contains a motor control program based on LabVIEW, which can set the motor speed and running time, and thus control the loading speed and depth.

[0057] like Figure 1 、 Figure 2 As shown, the motor in the loading mechanism is controlled by a computer program, enabling continuous or interrupted loading, respectively, to measure the conditions of a battery cell or small module 203 subjected to continuous mechanical abuse and to a certain degree of mechanical abuse. The wide motor speed range allows for both quasi-static mechanical loading experiments at low loading rates and dynamic mechanical loading experiments at higher loading rates.

[0058] like Figure 1 、 Figure 2As shown, the gas analysis and exhaust system includes a barometer 31, a sampling valve 29, an exhaust valve 30, a gas chromatograph 33, a gas pipeline 35, and an exhaust fan 34. The barometer 31, the sampling valve 29, and the exhaust valve 30 are installed on the constant volume bomb 8. The barometer 31 can measure the gas pressure inside the constant volume bomb 8 during the experiment, and the thermal runaway gas production can be estimated in combination with the ideal gas state equation. The gas chromatograph 33 is connected to the inside of the constant volume bomb 8 through the gas pipeline 35 and the sampling valve 29. Opening the sampling valve 29 can pass the thermal runaway gas in the constant volume bomb 8 into the gas chromatograph 33, and then analyze the components of the thermal runaway gas production. The exhaust fan 34 is connected to the exhaust valve 30 through the gas pipeline 35, and is used to discharge the exhaust gas in the constant volume bomb 8 after the experiment.

[0059] like Figure 8 As shown, the optical window system contains transparent quartz glass 205 or sapphire glass 3, which can withstand the high pressure during the experiment. The sapphire glass 3 is sandwiched between the large optical window flange 4 and the small optical window flange 5. The sapphire glass 3 and the large optical window flange 5 are sealed with an O-ring 6, and a gasket 7 is placed between the sapphire glass 3 and the small optical window flange 5. The large and small optical window flanges are connected by bolts. The large optical window flange 4 is connected to the constant volume bomb 8 by bolts. The optical window as a whole can be modularly fixed to the constant volume bomb 8 by bolts. The optical window system and the constant volume bomb 8 are sealed with an O-ring 6. The constant volume bomb 8 can be installed with zero to four different optical window systems according to experimental needs. The Schlieren optical diagnostic system requires a pair of quartz glass optical window systems 201 in opposite directions. Each infrared optical diagnostic system requires a sapphire glass optical window system 204. The particle image velocimetry system requires a pair of orthogonal quartz glass optical window systems 201.

[0060] like Figure 1 As shown, the Schlieren optical diagnostic system includes a point light source 39, a first plane mirror 40, a second plane mirror 43, a first concave mirror 41, a second concave mirror 42, a light knife 44, and a high-speed camera 45. Light is emitted from the point light source 39, changes direction after being reflected by the first plane mirror 40, and then forms parallel light after being reflected by the first concave mirror 41. The parallel light passes through the optical window and enters the interior of the constant volume bomb 8. The light will be deflected to varying degrees as the density of the medium changes. The light then passes through the optical window 201 facing it and reaches the second concave mirror 42. The second concave mirror 42 can focus the light on the blade of the light knife 44 after being reflected by the second plane mirror 43. The blade can cut the light source image at the focus. The deflected light cannot reach the imaging plane and leaves a shadow. The high-speed camera 45 behind the blade captures the Schlieren image of the experimental area. The schlieren method is suitable for intuitively observing the flow details in transparent media (such as air). After image processing, the density field, velocity field, shock wave and other transient flow field phenomena, flame morphology and propagation process of thermal runaway exhaust can be obtained.

[0061] like Figure 10 As shown, MATLAB software can be used to process schlieren optical images, sequentially performing grayscale conversion, static background subtraction, binarization, erosion, morphological closing operations, and edge detection to obtain the outline of the thermal runaway exhaust or flame. For the exhaust profile before hitting the wall, information such as penetration distance, cone angle, and velocity can be extracted.

[0062] like Figure 1 、 Figure 2 As shown, the infrared temperature measurement optical diagnostic system includes a first high-speed infrared thermal imager 46 and a second high-speed infrared thermal imager 47. Both high-speed infrared thermal imagers are placed outside the constant volume bomb, facing the sapphire glass optical window 204. The infrared radiation of the battery surface and the thermal runaway exhaust and flame can pass through the sapphire glass 3 and be recorded by the high-speed infrared thermal imager. When the first high-speed infrared thermal imager 46 is placed on the side of the constant volume bomb, the surface temperature field of the battery cell or small module, the temperature field of the jet gas, the influence range of the flame thermal radiation, and the movement of hot particles in the xy plane during the thermal runaway process can be obtained. When the second high-speed infrared thermal imager 47 is placed on the top surface of the constant volume bomb, the movement of hot particles in the yz plane and the thermal runaway propagation process of the battery small module can be observed, and the influence of hot particle sputtering on the thermal runaway propagation can be analyzed.

[0063] like Figure 2 As shown, the particle image velocimetry system includes a laser 48, a cylindrical mirror 49, a high-speed camera 45, and a synchronization controller 50. Laser 48, facing the quartz glass optical window 201, serves as a light source, emitting a pulsed beam. The pulsed beam passes through the cylindrical mirror 49, forming a planar light beam. This "light sheet" overlaps the axial longitudinal section of the battery cell or small module 203, illuminating the flow field region to be measured within the constant volume bomb 8. Particles or droplets in the thermal runaway exhaust are used as tracer particles. After being irradiated by the laser, the tracer particles scatter. Multiple high-speed cameras 45 placed on the front and rear sides capture images of the particle scattering in the region to be measured. The synchronization controller 50 is used to control the synchronization of the laser pulses of the laser 48 with the shutters of the high-speed cameras 45. A computer is used to perform three-dimensional reconstruction of the images captured by the multiple high-speed cameras 45. Three-dimensional cross-correlation calculations are performed on two temporally adjacent frames to obtain the displacement information of the tracer particles in three-dimensional space. The velocity field can be calculated based on the laser pulse time interval or the shutter time interval, enabling quantitative measurement of the three-dimensional flow field of the thermal runaway exhaust. If only one high-speed camera 45 is used to shoot from the front or back of the constant volume bomb, and a cross-correlation calculation is performed on two temporally adjacent frames, the displacement information of the tracer particles in the two-dimensional plane can be obtained. The velocity field can be calculated based on the laser pulse time interval or the shutter time interval, thereby achieving quantitative measurement of the two-dimensional plane flow field of the thermal runaway exhaust.

[0064] like Figure 9 As shown, the implementation steps of the present invention are as follows:

[0065] The first step is to place the constant volume bomb 8, fix the battery cell or small module 203 in the battery fixture 1, install the needle / extrusion head 28 at the appropriate position of the needle / extrusion head bracket 27 according to the experimental requirements, fix the loading mechanism at the appropriate position on the constant volume bomb 8, install the constant volume bomb sealing cover and the constant volume bomb sealing flange, install the optical window system, debug the Schlieren light path, place the high-speed infrared thermal imager, or place the laser 48 and the high-speed camera 45.

[0066] The second step is to start the high-speed camera 45 of the Schlieren optical diagnostic system, start the high-speed infrared thermal imager, or start the laser 48 and high-speed camera 45 of the particle image velocimetry system. Start the barometer.

[0067] The third step is to connect the power line of the stepper motor 11 to the motor controller 36, turn on the power supply 37, and set the speed and running time of the stepper motor 11 in the motor control program of the computer 38.

[0068] The fourth step is to start the stepper motor 11 and perform a mechanical abuse experiment.

[0069] Step 5: Save the optical image and record and save the barometer data.

[0070] The sixth step is to open the sampling valve 29 and pass the thermal runaway gas sample in the constant volume bomb 8 into the gas chromatograph 33. Start the vacuum pump 34 and open the exhaust valve 30 to discharge the exhaust gas in the constant volume bomb 8 into the laboratory exhaust pipe.

[0071] In the seventh step, the data from the barometer 31 is used to calculate the total amount of gas produced by thermal runaway, and the gas chromatograph 33 is used to analyze the components of the gas produced by thermal runaway. The schlieren optical image, infrared optical image, and particle velocimetry optical image are processed to obtain the density field, temperature field, velocity field, shock wave and other transient flow field phenomena of the thermal runaway exhaust, the flame morphology and propagation process, and the heat spread process of the small module.

[0072] Step 8: After cleaning the inside of the container 8, the next experiment can be carried out.

[0073] The above description is only a preferred embodiment of the present invention. Any equivalent changes and modifications made by any technician familiar with the present invention within the scope of the patent application of the present invention also fall within the scope covered by the claims attached to the present invention.

Claims

1. A multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnostic device, comprising a constant volume bomb, a battery clamp, a battery holder, a constant volume bomb sealing cover, and a constant volume bomb sealing flange, characterized in that It also includes a loading mechanism, a motor control system, a gas analysis and exhaust system, a quartz glass optical window system, and a sapphire glass optical window system; The constant volume bomb is a hollow cube with three pairs of orthogonal holes on its front, back, left, right, and top and bottom outer walls, each of which is provided with a mounting slot. The front, back, top, left, and right through-holes are used to accommodate a sapphire glass optical window system or a quartz glass optical window system or a loading mechanism, and the bottom through-hole is used to accommodate a sealing cover for the constant volume bomb. The constant volume bomb sealing cover is arranged in the through hole mounting groove on the lower side of the constant volume bomb, and the constant volume bomb sealing flange is arranged on the outer side of the constant volume bomb sealing cover and connected to the wall surface of the constant volume bomb by bolts; The battery clamp and battery support are located inside the constant volume bomb and are used to fix the battery cells or small modules. The battery clamp and battery support are connected to the constant volume bomb sealing cover on the lower side of the constant volume bomb by bolts. The loading mechanism includes a loading mechanism sealing cover, a loading mechanism sealing flange, a stepper motor, a motor supporting steel sleeve, a magnetic coupling, a ball screw mechanism, a pricking needle / extrusion head bracket, and a pricking needle / extrusion head. The loading mechanism sealing cover is arranged in the through-hole mounting groove of the constant volume bomb. The loading mechanism sealing flange is arranged on the outside of the loading mechanism sealing cover and is connected to the wall surface of the constant volume bomb by bolts. The motor supporting steel sleeve and the loading mechanism sealing cover are connected together by bolts. The stepper motor is connected to the motor supporting steel sleeve by bolts. The output shaft of the stepper motor is connected to the magnetic coupling. The magnetic coupling is connected to the ball screw mechanism. The ball screw mechanism is connected to the pricking needle / extrusion head. The pricking needle / extrusion head is arranged on the pricking needle / extrusion head bracket. The motor control system includes a motor power supply, a motor controller, and a computer. The motor control system is arranged outside the constant volume bomb, and the motor controller is connected to the motor power supply, the computer, and the stepper motor through a wiring harness. The gas analysis and exhaust system includes a barometer, a sampling valve, an exhaust valve, a gas chromatograph, a gas pipeline, and an exhaust fan. The barometer, sampling valve, and exhaust valve are all installed on the constant volume bomb. The gas chromatograph is connected to the sampling valve through a gas pipeline, and the exhaust fan is connected to the exhaust valve through a gas pipeline. The sapphire glass optical window system includes a large optical window flange, a small optical window flange, and sapphire glass. The large optical window flange is connected to the wall of the constant volume bomb by bolts. The sapphire glass is arranged between the large optical window flange and the small optical window flange. The large optical window flange and the small optical window flange are connected together by bolts. The quartz glass optical window system includes a large optical window flange, a small optical window flange, and quartz glass. The large optical window flange is connected to the wall of the constant volume bomb through bolts. The quartz glass is arranged between the large optical window flange and the small optical window flange. The large optical window flange and the small optical window flange are connected together through bolts.

2. The multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnostic device according to claim 1, characterized in that It also includes a Schlieren optical diagnostic system, which includes a point light source, a first plane mirror, a first concave mirror, a second concave mirror, a second plane mirror, a light knife, and a high-speed camera. Quartz glass optical window systems are arranged in the front and rear through holes of the constant volume bomb, and a loading mechanism is arranged in the left through hole of the constant volume bomb. The point light source, the first plane mirror, and the first concave mirror are arranged at the rear side of the exterior of the constant volume bomb, and the second concave mirror, the second plane mirror, the light knife, and the high-speed camera are arranged at the front side of the exterior of the constant volume bomb. Light is emitted from the point light source, passes through the first plane mirror, the first concave mirror, the rear quartz glass optical window system, the interior of the constant volume bomb, the front quartz glass optical window system, the second concave mirror, the second plane mirror, and the light knife in sequence, and is captured by the high-speed camera.

3. The multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnostic device according to claim 1, characterized in that It also includes an infrared temperature measurement optical diagnostic system, which includes a first high-speed infrared thermal imager and a second high-speed infrared thermal imager. Sapphire glass optical window systems are arranged on the upper side and right side through holes of the constant volume bomb, and a loading mechanism is arranged on the left side through hole of the constant volume bomb. The first high-speed infrared thermal imager and the second high-speed infrared thermal imager are both arranged outside the constant volume bomb, the first high-speed infrared thermal imager faces the right side sapphire glass optical window system, and the second high-speed infrared thermal imager faces the upper side sapphire glass optical window system.

4. The multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnostic device according to claim 1, characterized in that It also includes a particle image velocimetry system, which includes a laser, a cylindrical mirror, a high-speed camera, and a synchronous controller. A quartz glass optical window system is arranged in the upper, front, and rear through holes of the constant volume bomb, and a loading mechanism is arranged in the left through hole of the constant volume bomb. The laser, cylindrical mirror, high-speed camera, and synchronous controller are all arranged outside the constant volume bomb, with the laser facing the upper quartz glass optical window system, the cylindrical mirror is arranged between the laser and the quartz glass optical window system, and multiple high-speed cameras are respectively arranged outside the front and rear quartz glass optical window systems. The laser and the high-speed camera are connected to the synchronous controller through a wiring harness.

5. The multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnostic device according to claims 1 to 4, characterized in that The constant volume bomb sealing cover is a solid steel cylinder, and an O-ring is used to seal the constant volume bomb sealing cover and the constant volume bomb.

6. The multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnostic device according to claim 5, characterized in that The magnetic coupling includes an outer rotor, an isolation sleeve, and an inner rotor. Keyways are provided on both the outer rotor and the inner rotor of the magnetic coupling. The output shaft of the stepper motor is connected to the outer rotor of the magnetic coupling via a key. One end of the lead screw passes through the center hole of the sealing cover of the loading mechanism and is connected to the inner rotor of the magnetic coupling via a key.

7. The multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnostic device according to claim 6, characterized in that The ball screw mechanism includes a screw, a screw nut, a screw nut seat, a screw fixing seat, a screw support seat, a screw support connecting plate, and a linear guide rail. The screw is supported by the screw fixing seat and the screw support seat. The screw fixing seat is fixed to the inner surface of the loading mechanism sealing cover by bolts; the screw fixing seat and the screw support seat are respectively connected to the screw support connecting plate by bolts to fix the screw support seat.

8. The multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnostic device according to claim 7, characterized in that There is a hole on both sides of the screw fixing seat, screw nut, screw nut seat and screw support seat for installing a linear guide rail, and the linear guide rail constrains the screw nut and the screw nut seat to perform linear motion.

9. The multi-window lithium-ion battery mechanical abuse gas analysis and optical diagnostic device according to claim 8, characterized in that The needle / extrusion head bracket is fixed on the screw nut seat by bolts. A plurality of bolt holes are opened on the end surface of the needle / extrusion head bracket, and the tail of the needle / extrusion head is threaded.

Images