Cylindrical battery needle test device and method

Abstract

The application provides a cylindrical battery needle puncture testing device and method, and relates to the field of battery safety testing. The device comprises a mounting frame, a clamping mechanism, a detection mechanism and a needle puncture mechanism. The clamping mechanism clamps the cylindrical battery, the detection mechanism is connected with the explosion-proof valve, and the gas pressure discharged by the explosion-proof valve is detected. The needle puncture mechanism comprises a driving device and a puncture needle, and the surface of the puncture needle is provided with a sealing layer of low-melting-point alloy and solidification accelerator. The melting point of the low-melting-point alloy ranges from 80 to 150 DEG C, and the low-melting-point alloy melts and fills the gap between the puncture hole and the needle body when the battery is in thermal runaway, thereby preventing gas leakage. The solidification accelerator is uniformly dispersed in the low-melting-point alloy, and the solidification mechanism is triggered after the sealing layer melts, thereby forming a dense sealing structure and ensuring that the gas is discharged only through the explosion-proof valve instead of leaking through the puncture hole gap. The device effectively solves the problem of gas leakage in traditional needle puncture testing, and improves the accuracy and reliability of the explosion-proof pressure relief test.

Description

Technical Field

[0001] This application relates to the field of battery safety testing, and in particular to a cylindrical battery needle penetration test device and method. Background Technology

[0002] With the rapid development of new energy vehicles and the energy storage industry, cylindrical batteries have become one of the mainstream technologies in the power battery field due to their advantages such as high energy density and standardized manufacturing. However, the safety of batteries under extreme conditions (such as mechanical abuse and thermal runaway) remains a core concern for the industry. The nail penetration test, as a key experimental method for simulating thermal runaway caused by internal short circuits in batteries, is widely used in domestic and international safety standards such as GB / T31485 and UL1642. Its test results are directly related to core technical aspects such as the burst pressure design of explosion-proof valves and the optimization of module thermal management strategies.

[0003] In existing technologies, the needle penetration test involves driving a metal needle to instantly puncture the battery casing, artificially triggering an internal short circuit and monitoring key parameters such as internal pressure changes and gas release during thermal runaway. As the only controllable pressure relief channel during battery thermal runaway, the explosion-proof valve's burst pressure threshold must be strictly matched to the battery's gas production characteristics: if the burst pressure is designed too high, it may cause the entire casing to rupture, leading to a secondary accident; if it is designed too low, frequent accidental opening may cause battery performance degradation. Therefore, accurately obtaining the battery's internal pressure-time curve and pressure relief gas flow data during the needle penetration process is the core basis for the scientific design of the explosion-proof valve.

[0004] However, current needle penetration testing devices still face significant technical bottlenecks in practical applications. After the needle penetrates the battery casing, gaps often form between the needle and the casing, causing gas to leak out. Due to these gaps, gas leaks not only through the explosion-proof valve but also through gaps around the puncture hole, creating parallel leakage paths. This parallel path causes gas to leak from inside the battery through multiple channels, rather than just through the single channel of the explosion-proof valve. Especially in the early stages of thermal runaway (pressure 5-20 kPa), the parallel leakage paths between the puncture hole and the explosion-proof valve, along with the multi-channel gas leakage, severely underestimate the actual pressure relief of the explosion-proof valve, with measured data fluctuating by as much as ±30%. This makes it impossible to provide reliable input for burst pressure calibration, and these problems seriously affect the accuracy and reliability of the test results.

[0005] Application content

[0006] In view of this, this application proposes a cylindrical battery needle penetration test device and method, which aims to solve the problem of inaccurate pressure relief test results caused by the parallel venting path between the puncture hole and the explosion-proof valve during the needle penetration test.

[0007] The technical solution of this application is implemented as follows:

[0008] On one hand, this application provides a cylindrical battery needle penetration testing device, characterized in that it includes:

[0009] Mounting rack;

[0010] The clamping mechanism is fixedly mounted on the mounting bracket and is used to clamp and fix the cylindrical battery.

[0011] The testing mechanism, fixedly mounted on the mounting frame, is used to connect with the explosion-proof valve of the cylindrical battery to test the gas pressure released from the explosion-proof valve port.

[0012] A needle puncture mechanism includes a drive device and a puncture needle. The drive device is used to drive the puncture needle to move and puncture a cylindrical battery. The puncture needle includes a needle body and a sealing layer disposed on the outer surface of the needle body. The sealing layer includes a low-melting-point alloy and a solidification accelerator. The low-melting-point alloy has a melting point range of 80-150°C and is used to melt and fill the gap between the puncture hole and the needle body at a high temperature of 80-200°C generated by battery thermal runaway. The solidification accelerator is uniformly dispersed in the low-melting-point alloy and is used to trigger a solidification mechanism after the sealing layer melts, so as to form a dense sealing structure in the gap between the puncture hole and the needle body. The triggering condition of the solidification accelerator is configured to start solidification after the sealing layer is fully filled.

[0013] Based on the above technical solution, preferably, the low-melting-point alloy is a bismuth-based alloy layer, the composition of which, by mass percentage, includes: bismuth content of 55%-60%; tin content of 30%-38%; indium content of 5%-10%; silicon carbide whisker content of 5%-10%, with a length of 10-20μm and a diameter of 0.5-1μm, uniformly dispersed in the alloy; the sealing layer has a thickness of 90-110μm and covers the outer surface of the needle body; the solidification accelerator is one or more of pressure-sensitive polymers, curing agent microcapsules, and nano-alumina particles.

[0014] Based on the above technical solution, preferably, the puncture needle further includes a transition layer and an impact layer. The transition layer covers the outer surface of the puncture needle body and is used to enhance the bonding force between the puncture needle body and the sealing layer. The impact layer covers the outer surface of the transition layer and is used to improve the hardness and wear resistance of the puncture needle. The sealing layer covers the outer surface of the impact layer.

[0015] Based on the above technical solution, preferably, the transition layer is nickel-based, with a thickness of 3-8 μm and an adhesion strength ≥40 MPa; the impact layer is silicon carbide, with a thickness of 20-40 μm and a hardness ≥2200 HV.

[0016] Based on the above technical solution, preferably, the puncture needle further includes a lubricating layer, which covers the outer surface of the sealing layer. The lubricating layer is hexagonal boron nitride with a thickness of 1±3μm, a friction coefficient ≤0.15, and a grain size ≤200nm.

[0017] Based on the above technical solution, preferably, the clamping mechanism includes a radial clamping assembly and an axial clamping assembly. Two sets of radial clamping assemblies are symmetrically arranged for clamping the cylindrical battery radially in the horizontal direction. The axial clamping assembly is used to push one end of the cylindrical battery horizontally. The detection mechanism is located at the end of the cylindrical battery away from the axial clamping assembly. It includes a fixed flange and a detection assembly. The fixed flange is fixedly installed on the top surface of the support frame and has a connection port. One end of the connection port is used for sealing connection with the explosion-proof valve of the cylindrical battery, and the other end is connected to the detection assembly. The detection assembly is used to collect the gas pressure data and gas composition of the gas released from the explosion-proof valve.

[0018] Based on the above technical solution, preferably, the radial clamping assembly includes a first clamping cylinder and a first clamping member. The first clamping cylinder is horizontally fixed on the top surface of the mounting bracket and is used to drive the first clamping member to move along the radial direction of the cylindrical battery. The axial clamping assembly includes a second clamping cylinder and a second clamping member. The second clamping cylinder is fixedly disposed on the top surface of the mounting bracket and is used to drive the second clamping member to translate towards the connection port.

[0019] Based on the above technical solution, preferably, a temperature sensor is provided on the side of the first clamping member that contacts the cylindrical battery.

[0020] Based on the above technical solution, preferably, the detection component includes a detection cavity, a pressure sensor, and a MEMS mass spectrometry chip. One end of the detection cavity is connected to the connection port, and the other end extends axially. Its inner cavity includes a contraction section and an expansion section. The contraction section is located between the connection port and the expansion section, and its inner diameter gradually decreases from the connection port to the expansion section. The inner diameter of the expansion section gradually increases from the end of the contraction section away from the connection port. The pressure sensor is disposed inside the connection port and is used to collect gas pressure data released from the explosion-proof valve port. The MEMS mass spectrometry chip is disposed at the end of the expansion section away from the contraction section and is used to collect the gas composition released from the explosion-proof valve port.

[0021] Based on the above technical solution, preferably, it also includes a fire extinguishing device, which includes a fire detector and a water storage tank. The fire detector is set inside the detection port and is used to detect the fire signal generated when the cylindrical battery thermally runs away. The water storage tank is set below the mounting frame, and the top surface of the mounting frame has a through hole for the cylindrical battery to fall into the water storage tank when the fire signal is triggered.

[0022] Based on the above technical solution, preferably, it also includes a protective box and a support mechanism. The mounting frame is disposed in the protective box, the driving device is fixedly disposed on the top surface inside the protective box, the water storage tank and the moving device are disposed on the bottom surface inside the protective box, and two sets of support mechanisms are symmetrically arranged, respectively located on both sides below the length direction of the through hole. The support mechanism includes a fixed frame, a support member, a first telescopic element and a second telescopic element. The fixed frame is fixedly connected to the mounting frame. The first telescopic element is fixedly disposed on the fixed frame and is used to drive the second telescopic element to move horizontally in the length direction of the through hole. The second telescopic element is used to drive the support member to pass upward through the through hole and lift the cylindrical battery.

[0023] Secondly, this application discloses a method for testing the needle penetration of a cylindrical battery, which utilizes the cylindrical battery needle penetration testing device described in the first aspect, and includes the following steps:

[0024] S1. Place the cylindrical battery horizontally at the through hole on the top surface of the mounting bracket, align the explosion-proof valve of the cylindrical battery with the connection port, clamp and position the cylindrical battery axially using the axial clamping assembly, and clamp and position the cylindrical battery radially using the radial clamping assembly.

[0025] S2. The driving device drives the puncture needle to pierce the cylindrical battery vertically downward. The low melting point alloy on the sealing layer melts at a high temperature of 80-200℃ generated by the thermal runaway of the battery and fills the gap between the puncture hole and the needle body. The solidification accelerator on the sealing layer triggers the solidification mechanism after the sealing layer melts, forming a dense sealing structure in the gap between the puncture hole and the needle body.

[0026] S3. When thermal runaway occurs inside the cylindrical battery, the explosion-proof valve pressure relief port begins to release high-pressure gas. The pressure sensor in the detection component collects the gas pressure data released from the explosion-proof valve port, the MEMS mass spectrometry chip collects the gas composition released from the explosion-proof valve port, and transmits it to the data processing system for analysis in real time.

[0027] S4. When a fire signal is detected at the explosion-proof valve port by the fire detector, the clamping mechanism releases the clamp on the cylindrical battery, the drive device releases the clamp on the puncture needle, and the puncture needle falls into the water storage tank through the through hole along with the cylindrical battery to extinguish the fire.

[0028] This application has the following advantages over the prior art:

[0029] (1) The cylindrical battery needle penetration testing device disclosed in this application, by setting a sealing layer of low-melting-point alloy and solidification accelerator on the surface of the puncture needle, can effectively fill the gap between the puncture hole and the puncture needle during thermal runaway, preventing gas leakage through these gaps. This solves the problem of gas leakage caused by the gap between the puncture needle and the battery casing in traditional needle penetration testing, thereby ensuring the accuracy of the test results. Due to the presence of the sealing layer, the gas will only be depressurized through the explosion-proof valve channel, rather than through the puncture hole gap, thus enabling the actual depressurization of the explosion-proof valve to be accurately measured. This solves the problem of underestimation of the explosion-proof valve depressurization caused by multi-channel gas leakage, improving the reliability of the explosion-proof depressurization test.

[0030] (2) Through the synergistic effect of low melting point alloy and solidification accelerator, the sealing layer melts rapidly in the early stage of battery thermal runaway (80-150℃) and fills the gap between the puncture hole and the needle body. Then, under the trigger of solidification accelerator, it solidifies rapidly to form a dense sealing structure, effectively blocking the gas leakage path and ensuring that the gas is released only through the explosion-proof valve, thereby improving the accuracy of explosion-proof pressure relief test.

[0031] (3) By setting a temperature sensor on the side of the first clamping member that contacts the cylindrical battery, temperature detection can be performed more intuitively. At the same time, there is no need to manually attach thermocouples or other types of temperature sensors to the surface of the cylindrical battery, which can avoid the temperature from being too high and causing the thermocouple to slip off the cylindrical battery, thus affecting temperature detection.

[0032] (4) By setting pressure sensors and MEMS mass spectrometry chips in the detection components, the leakage pressure and gas composition of cylindrical batteries can be collected synchronously. These data provide important basis for improving battery design and manufacturing process, optimizing battery pack layout and improving overall safety, ensuring that the battery can still work safely and reliably under extreme conditions.

[0033] (5) By setting a contraction section and an expansion section in the detection cavity, the inner diameter of the contraction section gradually decreases from the connection port to the expansion section, its cross-sectional area gradually decreases, the flow rate increases, and the pressure decreases. The inner diameter of the expansion section gradually increases from the end of the contraction section away from the connection port, its cross-sectional area gradually increases, the flow rate slows down, and the pressure further decreases. Placing the MEMS mass spectrometry chip at the end of the expansion section helps to avoid the direct impact of high-pressure airflow on the chip, because the airflow has been significantly slowed down and depressurized when passing through the contraction section and the expansion section, thereby protecting the MEMS mass spectrometry chip from damage and reducing the interference of particulate matter.

[0034] (6) By setting through holes on the mounting frame, setting a water storage tank on the bottom surface of the mounting frame, and setting a fire detector in the detection port, when the fire detector triggers the fire extinguishing measures, the clamping mechanism quickly releases the clamping of the cylindrical battery, and at the same time the drive device also releases the clamping of the puncture needle. At this time, the cylindrical battery will fall into the water storage tank through the through hole on the top surface of the mounting frame to achieve the fire extinguishing operation and avoid the cylindrical battery from catching fire during the needle penetration test and causing damage to the detection components.

[0035] (7) By introducing a support mechanism, the cylindrical battery clamping and positioning can be completed efficiently and accurately during the process, which not only improves clamping efficiency and accuracy but also simplifies the operation process and reduces the burden of manual operation. The automated support and positioning system ensures the stability of the battery, further improves the safety of the testing process, and provides a guarantee for emergency handling in case of thermal runaway. This design effectively improves the performance and safety of the testing device, making the entire testing process smoother and more efficient. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a three-dimensional structural schematic diagram of the cylindrical battery nail penetration test device disclosed in this application;

[0038] Figure 2 This is a three-dimensional schematic diagram of the internal structure of the cylindrical battery nail penetration test device disclosed in this application;

[0039] Figure 3 This is a schematic diagram of the planar structure of the puncture needle disclosed in this application;

[0040] Figure 4 This is a top view of the internal structure of the cylindrical battery nail penetration test device disclosed in this application;

[0041] Figure 5 for Figure 4 Planar sectional view at point AA;

[0042] Figure 6 This is a three-dimensional structural diagram of the clamping mechanism disclosed in this application;

[0043] Figure 7 This is a three-dimensional structural schematic diagram of the radial clamping assembly disclosed in this application;

[0044] Figure 8This is a three-dimensional structural diagram of the supporting structure disclosed in this application;

[0045] Figure label:

[0046] 1. Mounting bracket; 2. Clamping mechanism; P. Cylindrical battery; 3. Detection mechanism; 4. Needle piercing mechanism; 41. Drive device; 42. Puncture needle; 421. Puncture needle body; 422. Sealing layer; 423. Transition layer; 21. Radial clamping assembly; 22. Axial clamping assembly; 211. First clamping cylinder; 212. First clamping element; 221. Second clamping cylinder; 222. Second clamping element; 31. Fixed flange; 32. Detection assembly; 33. 321. Connection port; 322. Detection chamber; 323. Pressure sensor; 321. MEMS mass spectrometry chip; 3211. Contraction section; 3212. Expansion section; 324. Filter device; 5. Fire extinguishing device; 51. Fire detector; 52. Water storage tank; 11. Through hole; 6. Protective box; 7. Support mechanism; 71. Fixing frame; 72. Support component; 73. First telescopic element; 74. Second telescopic element; 8. Pull-out cylinder; T. Temperature sensor. Detailed Implementation

[0047] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0048] like Figure 1 As shown, combined with Figure 2 and 3 This application discloses a cylindrical battery needle penetration test device, including a mounting frame 1, a clamping mechanism 2, a detection mechanism 3, and a needle penetration mechanism 4.

[0049] Among them, the mounting frame 1 is the supporting structure of the entire device, used to fix the clamping mechanism 2 and the detection mechanism 3, so as to ensure that each component remains stable during the test.

[0050] The clamping mechanism 2, fixedly mounted on the mounting bracket 1, is used to clamp and secure the cylindrical battery P, ensuring that it does not shift or tilt during the puncture process. In this embodiment, the cylindrical battery is clamped horizontally, which facilitates the puncture operation in the vertical direction.

[0051] The detection mechanism 3 is fixedly mounted on the mounting bracket 1 and is used to connect with the explosion-proof valve of the cylindrical battery to detect the gas pressure released from the explosion-proof valve port. In some embodiments, by connecting the detection mechanism 3 to a computer, the pressure curve can be displayed in real time, providing accurate data on the amount of pressure released when the cylindrical battery experiences thermal runaway, and providing a basis for evaluating the safety performance of the cylindrical battery.

[0052] The needle puncture mechanism 4 includes a drive device 41 and a puncture needle 42. The drive device 41 is used to drive the puncture needle 42 to puncture the cylindrical battery at a certain speed. In this embodiment, the drive device 41 is disposed above the mounting bracket 1 and is used to control the moving speed and depth of the puncture needle 42 in the vertical direction. In some embodiments, the drive device 41 can adopt a stepper motor plus a ball screw structure to achieve accurate displacement control.

[0053] In the existing technology, when the puncture needle 42 punctures the cylindrical battery, it forms a puncture hole on the casing of the cylindrical battery. There is a certain gap between the puncture needle 42 and the puncture hole. When thermal runaway occurs in the cylindrical battery, the gas inside the cylindrical battery will leak from the gap. At the same time, the gas will also be depressurized through the explosion-proof valve, forming a parallel gas leakage path. Since the amount of gas pressure leakage at the gap cannot be obtained, the actual pressure relief of the explosion-proof valve is seriously underestimated due to multi-channel gas leakage. The measured data fluctuates by as much as ±30%, which cannot provide a reliable input for the explosion pressure calibration. These problems seriously affect the accuracy and reliability of the test results.

[0054] To address the aforementioned problems, this application proposes the following solution.

[0055] Specifically, the puncture needle 42 of this application includes a needle body 421 and a sealing layer 422 disposed on the outer surface of the needle body 421. The needle body can be made of high-strength alloy steel and has a diameter of 3mm to 5mm.

[0056] The sealing layer 422 comprises a low-melting-point alloy and a solidification accelerator. The low-melting-point alloy has a melting point range of 80-150°C and is used to melt and fill the gap between the puncture hole and the needle body 421 at high temperatures of 80-200°C caused by battery thermal runaway. This effectively prevents gas leakage through these gaps and avoids underestimation of the explosion-proof valve pressure relief due to multi-channel gas leakage during testing.

[0057] The solidification accelerator is uniformly dispersed in the low-melting-point alloy to trigger the solidification mechanism after the sealing layer 422 melts, so as to form a dense sealing structure in the gap between the puncture hole and the needle body 421. In this way, under thermal runaway, the sealing layer 422 will automatically solidify in a short time to form an effective seal and prevent gas from leaking through this path.

[0058] In this embodiment, the coagulation accelerator is triggered when it begins to solidify after the sealing layer 422 is fully filled. As a result, the sealing layer 422 automatically solidifies within 3-10 seconds, achieving a sealing strength ≥20 MPa, ensuring a long-lasting and reliable effect.

[0059] By providing a sealing layer 422 of low-melting-point alloy and solidification accelerator on the surface of the puncture needle 42, the gap between the puncture hole and the puncture needle 42 can be effectively filled during thermal runaway, preventing gas leakage through these gaps. This solves the gas leakage problem caused by the gap between the puncture needle 42 and the battery casing in traditional needle penetration tests, thus ensuring the accuracy of the test results. Due to the presence of the sealing layer 422, gas will only be depressurized through the explosion-proof valve channel, rather than through the puncture hole gap, allowing the actual pressure relief of the explosion-proof valve to be accurately measured. This solves the problem of underestimation of the explosion-proof valve pressure relief caused by multi-channel gas leakage, improving the reliability of the test.

[0060] In some implementations, the low-melting-point alloy is a bismuth-based alloy layer. This bismuth-based alloy layer, serving as the main material of the sealing layer 422, has a low melting point (80-150°C) and high fluidity, enabling it to rapidly melt and fill the gap between the puncture hole and the needle body 421 during battery thermal runaway. The low melting point of the bismuth-based alloy allows it to melt in the early stages of battery thermal runaway (80-200°C), ensuring that the sealing layer 422 functions promptly, blocking parallel venting paths, and ensuring that gas is released only through the explosion-proof valve.

[0061] The bismuth-based alloy layer comprises bismuth, tin, and silicon carbide whiskers, and its composition by mass percentage includes: 55%-60% bismuth; 30%-38% tin; and 5%-10% silicon carbide whiskers.

[0062] Bismuth is the main component of bismuth-based alloys, and its content directly affects the alloy's melting point and fluidity. A bismuth content of 55%-60% ensures that the alloy melts within the range of 80-150℃ while maintaining good fluidity. It should be noted that too low a bismuth content will lead to an increased melting point, making it difficult to melt in the early stages of thermal runaway, while too high a bismuth content may result in insufficient alloy strength, making it unable to effectively fill gaps.

[0063] Tin, as a minor component of bismuth-based alloys, is used to adjust the alloy's mechanical properties and solidification rate. A tin content of 30%-38% ensures that the alloy solidifies rapidly after melting, forming a dense, sealed structure. It should be noted that too low a tin content will result in a slow solidification rate, making it difficult to maintain a seal under high-pressure gas; while too high a tin content may lead to reduced alloy fluidity, preventing complete filling of gaps.

[0064] Indium has a low melting point, and its addition to bismuth-based alloys can further lower the alloy's melting point, making it easier to melt in the early stages of battery thermal runaway (80-150℃). The addition of indium brings the alloy's melting temperature range closer to the battery's thermal runaway temperature range (80-200℃), ensuring that the sealing layer 422 functions effectively. The indium content is 5%-10%. Too low an indium content (<5%) may result in insufficient alloy fluidity, failing to completely fill the gaps; too high an indium content (>10%) may result in excessive alloy fluidity, increasing the risk that the sealing layer 422 may be blown away by high-pressure gas.

[0065] Silicon carbide whiskers are used as a reinforcing material to improve the mechanical strength and wear resistance of bismuth-based alloys. A silicon carbide whisker content of 5%-10% ensures sufficient impact resistance during puncture. The silicon carbide whiskers are 10-20 μm in length and 0.5-1 μm in diameter, and are uniformly dispersed in the alloy to ensure a uniform reinforcing effect.

[0066] In this embodiment, the total thickness of the sealing layer 422 is 90-110μm, covering the outer surface of the needle body 421. The thickness is set to ensure that the sealing layer 422 can completely fill the gap after melting, while having sufficient mechanical strength to withstand the action of high-pressure gas.

[0067] While tin can accelerate the solidification rate of bismuth-based alloys, its solidification rate is still limited by alloy composition and ambient temperature. Under extreme conditions (such as high-pressure gas), tin alone may not be sufficient to ensure rapid solidification of the sealing layer 422. The solidification rate of tin is insufficient to completely prevent the sealing layer 422 from being blown away under high-pressure gas, potentially leading to an increased leakage rate.

[0068] To this end, this application also uniformly disperses a solidification accelerator in the low-melting-point alloy. The solidification accelerator is one or more of pressure-sensitive polymers, curing agent microcapsules, and nano-alumina particles. The addition of the solidification accelerator can significantly improve the solidification rate of the sealing layer 422. Tin and the solidification accelerator have a synergistic effect; tin regulates the solidification rate of the alloy, while the solidification accelerator ensures rapid solidification of the sealing layer 422 under extreme operating conditions.

[0069] The low-melting-point alloy (bismuth-based alloy) has a melting point range of 80-150℃, melting rapidly in the early stages of battery thermal runaway (80-200℃). The alloy's melting temperature matches the thermal runaway temperature range, ensuring the sealing layer 422 functions effectively in the early stages of thermal runaway. The low-melting-point alloy exhibits high fluidity after melting, enabling it to rapidly fill the gap between the puncture hole and the needle body 421 under gravity or pressure. This fluidity ensures the sealing layer 422 is uniformly distributed after melting, forming a dense filling structure. Under the pressure generated by thermal runaway, the molten alloy rapidly flows into the gap between the puncture hole and the needle body 421, completing the filling. The filling time window is from alloy melting to solidification, completed within a few seconds to tens of seconds.

[0070] Solidification accelerators (such as pressure-sensitive polymers, curing agent microcapsules, and nano-alumina particles) begin to function under specific conditions (such as high temperature or high pressure). The triggering conditions match the melting temperature of the sealing layer 422, ensuring that the sealing layer 422 begins to solidify after being fully filled. For example, pressure-sensitive polymers undergo cross-linking reactions at 10 MPa pressure, accelerating the solidification of the sealing layer 422. Curing agent microcapsules rupture at 150°C, releasing the curing agent and triggering the solidification of the sealing layer 422; nano-alumina particles increase the solidification rate of the sealing layer 422 by increasing nucleation points. Low-melting-point alloys fill the gaps after melting, and the solidification accelerator triggers the solidification mechanism after the sealing layer 422 is fully filled, ensuring that the sealing layer 422 solidifies rapidly. The addition of solidification accelerators can significantly improve the solidification rate of the sealing layer 422, prevent it from being blown away by high-pressure gas, and greatly reduce the leakage at the puncture hole gap.

[0071] In some implementations, the pressure-sensitive polymer is specifically polydimethylsiloxane (PDMS) + a crosslinking agent (such as tetraethoxysilane, TEOS). PDMS undergoes a crosslinking reaction under high pressure, forming a three-dimensional network structure and improving the mechanical strength of the sealing layer. The crosslinking agent (such as TEOS) promotes the crosslinking and curing of PDMS under pressure.

[0072] In other embodiments, the pressure-sensitive polymer is specifically epoxy resin (EP) + amine curing agent (such as DETA, TETA). Under high pressure, the epoxy resin can accelerate the crosslinking reaction with the amine curing agent and increase the curing speed.

[0073] As some implementations, the shell material of the curing agent microcapsules is polymethyl methacrylate (PMMA), polystyrene (PS), or urea-formaldehyde resin (UF). The curing agent material in the microcapsules is benzoyl peroxide (BPO) (a free radical initiator used in polymerization reactions), diaminodiphenylmethane (DDM) (an epoxy resin curing agent), or dicyandiamide (DICY) (a latent curing agent that releases at high temperatures).

[0074] Example 1: The low-melting-point alloy composition is 58% Bi, 32% Sn, and 10% In. The silicon carbide whisker content is 8%, with a length of 15 μm and a diameter of 0.8 μm, uniformly dispersed in the alloy. The sealing layer 422 has a thickness of 100 μm, and the solidification accelerator is a pressure-sensitive polymer with a content of 1%. It undergoes a cross-linking reaction under a pressure of 10 MPa, accelerating the solidification of the sealing layer 422.

[0075] Example 2: The low-melting-point alloy composition is 55% Bi, 35% Sn, and 10% In. The silicon carbide whisker content is 10%, with a length of 20 μm and a diameter of 1 μm, uniformly dispersed in the alloy. The sealing layer 422 has a thickness of 110 μm, and the solidification accelerator is a curing agent microcapsule with a diameter of 8 μm, containing a curing agent. It ruptures and releases the curing agent at a high temperature of 150°C, triggering the solidification of the sealing layer 422.

[0076] Example 3: The low-melting-point alloy composition is 60% Bi, 30% Sn, and 10% In. The silicon carbide whisker content is 5%, with a length of 10 μm and a diameter of 0.5 μm, uniformly dispersed in the alloy. The sealing layer 422 has a thickness of 90 μm, and the solidification accelerator is nano-alumina particles with a particle size of 80 nm and a content of 2%, used to improve the solidification rate of the sealing layer 422.

[0077] Through the synergistic effect of low-melting-point alloy and solidification accelerator, the sealing layer 422 rapidly melts and fills the gap between the puncture hole and the needle body 421 in the early stage of battery thermal runaway (80-150℃). Subsequently, it rapidly solidifies under the trigger of solidification accelerator to form a dense sealing structure, effectively blocking the gas leakage path and ensuring that the gas is released only through the explosion-proof valve, thereby improving the accuracy of explosion-proof pressure relief test.

[0078] As one embodiment, the puncture needle 42 further includes a transition layer 423 disposed between the sealing layer 422 and the needle body. The transition layer 423 is nickel-based, with a thickness of 3-8 μm and an adhesion strength ≥40 MPa. The transition layer 423 is used to enhance the adhesion between the needle body 421 and the sealing layer 422, preventing them from falling off during puncture.

[0079] To achieve horizontal clamping and positioning of cylindrical batteries, the clamping mechanism 2 in this embodiment includes a radial clamping assembly 21 and an axial clamping assembly 22. Two sets of radial clamping assemblies 21 are symmetrically arranged to clamp the cylindrical battery radially in the horizontal direction. The symmetrical arrangement design can apply force evenly, ensuring that the cylindrical battery is stably fixed in the radial direction, avoiding displacement or rotation of the battery during the test, thereby improving test accuracy and repeatability.

[0080] In this embodiment, refer to the appendix Figure 3-7As shown, the radial clamping assembly 21 includes a first clamping cylinder 211 and a first clamping member 212. The first clamping cylinder 211 is horizontally fixed to the top surface of the mounting bracket 1 and is used to drive the first clamping member 212 to move along the radial direction of the cylindrical battery. The two first clamping members 212 move closer to each other in the horizontal direction to clamp the cylindrical battery in the radial direction. In this embodiment, the surface of the first clamping member 212 has a V-groove, which can be used to clamp cylindrical batteries with a diameter of 14-60mm.

[0081] The axial clamping assembly 22 is used to push one end of the cylindrical battery horizontally. In order to position the cylindrical battery in the axial direction, the detection mechanism 3 is set at the end of the cylindrical battery away from the axial clamping assembly 22 in this embodiment. It includes a fixed flange 31 and a detection assembly 32. The fixed flange 31 is fixedly set on the top surface of the support frame and has a connection port 33. One end of the connection port 33 is used to seal and connect with the explosion-proof valve of the cylindrical battery, and the other end is connected to the detection assembly 32. The detection assembly 32 is used to collect the gas pressure data and gas composition of the gas released from the explosion-proof valve.

[0082] Using the above technical solution, the connection port 33 is fixed to the mounting bracket 1 by the fixing flange 31. When the cylindrical battery is placed horizontally, the end of the cylindrical battery with the explosion-proof valve is connected to the connection port 33, and then the other end of the cylindrical battery is pushed horizontally by the axial clamping assembly 22, thereby limiting the position of the cylindrical battery in the axial direction.

[0083] In this embodiment, the axial clamping assembly 22 includes a second clamping cylinder 221 and a second clamping member 222. The second clamping cylinder 221 is fixedly mounted on the top surface of the mounting bracket 1 and is used to drive the second clamping member 222 to translate towards the connection port 33. Specifically, the extension and retraction direction of the second clamping cylinder 221 coincides with the axis direction of the connection port 33. The second clamping member 222 is a pushing block, preferably a circular block. The second clamping cylinder 221 drives the second clamping member 222 to lie flat towards the connection port 33, thereby clamping and positioning the cylindrical battery in the axial direction.

[0084] It is worth noting that providing stable and reliable clamping and fixing in the axial direction can achieve a tight fit between the cylindrical battery end face of the connection port 33, so that the explosion-proof valve is located at the connection port 33, thereby ensuring that the gas path is unique when the explosion-proof valve is depressurized.

[0085] In some embodiments, during the needle penetration test, when the puncture needle 42 punctures the cylindrical battery, a short circuit occurs inside the cylindrical battery, resulting in thermal runaway and a rapid increase in temperature. In order to test the temperature change after thermal runaway of the cylindrical battery, this embodiment sets a temperature sensor T on the first clamping member 212. Specifically, the temperature sensor T is set on the side of the first clamping member 212 that contacts the cylindrical battery. This allows for more intuitive temperature detection and eliminates the need to manually attach thermocouples or other types of temperature sensors T to the surface of the cylindrical battery. This avoids the thermocouples from slipping off the cylindrical battery due to excessively high temperatures, which would affect temperature detection.

[0086] In some embodiments, several temperature sensors T can be spaced apart on the surface of the first clamping member 212 along the length of the cylindrical battery, which can acquire temperature data at different locations on the surface of the cylindrical battery, resulting in richer data acquisition.

[0087] In this embodiment, the sealing layer 422 creates a self-sealing gap between the puncture needle 42 and the cylindrical battery puncture hole, making the explosion-proof valve of the cylindrical battery the only venting path. When thermal runaway occurs, the internal pressure of the battery becomes too high, and the gas breaks through the explosion-proof valve and enters the detection component 32 through the connection port 33. By collecting the amount of gas pressure released at the explosion-proof valve, the change in internal gas pressure of the battery during thermal runaway can be evaluated, and the opening pressure of the explosion-proof valve can be verified as reasonable, thus verifying the performance of the explosion-proof valve.

[0088] During thermal runaway in cylindrical batteries, the released gases contain various components, reflecting different internal chemical reactions (such as electrolyte decomposition and reactions of positive and negative electrode materials). Analyzing the gas composition can identify the specific causes of battery thermal runaway, providing a basis for improving battery design and manufacturing processes.

[0089] To achieve simultaneous collection of the leakage pressure and gas composition of the cylindrical battery, this embodiment uses a detection component 32.

[0090] Specifically, the detection component 32 includes a detection chamber 321, a pressure sensor 322, and a MEMS mass spectrometry chip 323. One end of the detection chamber 321 is connected to the connection port 33, and the other end extends axially. The pressure sensor 322 is disposed inside the connection port 33 and is used to collect gas pressure data released from the explosion-proof valve. In this embodiment, the pressure sensor 322 is a SAW pressure sensor 322, which is located inside the connection port 33. When the explosion-proof valve is depressurized, the pressure sensor 322 can respond quickly and collect pressure data. Based on the depressurization time, pressure and time curve data can be obtained.

[0091] In order to obtain the gas composition, this embodiment uses a MEMS mass spectrometer chip 323 for detection. However, during the depressurization process of the explosion-proof valve, the high-pressure airflow carrying particulate matter will interfere with the MEMS mass spectrometer chip 323, and the high pressure of the airflow will cause impact on the MEMS mass spectrometer chip 323, resulting in damage to the components.

[0092] Therefore, in this embodiment, the inner cavity of the detection chamber 321 is configured as a contraction section 3211 and an expansion section 3212. The contraction section 3211 is located between the connection port 33 and the expansion section 3212, and its inner diameter gradually decreases from the connection port 33 to the expansion section 3212. The inner diameter of the expansion section 3212 gradually increases from the end of the contraction section 3211 toward the direction away from the connection port 33. The MEMS mass spectrometry chip 323 is disposed at the end of the expansion section 3212 away from the contraction section 3211 and is used to collect the gas components released from the explosion-proof valve port.

[0093] This configuration allows the inner diameter of the contraction section 3211 to gradually decrease from the connection port 33 towards the expansion section 3212, resulting in a gradually decreasing cross-sectional area, increased flow velocity, and decreased pressure. Conversely, the inner diameter of the expansion section 3212 gradually increases from the end of the contraction section 3211 towards the direction away from the connection port 33, resulting in a gradually increasing cross-sectional area, decreased flow velocity, and further decreased pressure. Placing the MEMS mass spectrometry chip 323 at the end of the expansion section 3212 helps avoid direct impact from the high-pressure airflow on the chip, as the airflow is significantly slowed and depressurized when passing through the contraction section 3211 and the expansion section 3212, thus protecting the MEMS mass spectrometry chip 323 from damage and reducing interference from particulate matter.

[0094] As one implementation, a filter device 324 is also provided in the expansion section 3212. The filter device 324 is located in front of the MEMS mass spectrometry chip 323 and is used to filter out particulate matter carried by the high-pressure gas to prevent the particulate matter from damaging the MEMS mass spectrometry chip 323. In this embodiment, the filter device 324 includes a sintered metal filter screen and a silicon carbide ceramic filter element. The sintered metal filter screen is located at the outlet of the expansion cavity and has a pore size of 50 μm to intercept large particles; the silicon carbide ceramic filter element has a pore size of 5 μm to further filter micron-sized residues.

[0095] By incorporating a pressure sensor 322 and a MEMS mass spectrometer chip 323 within the detection component 32, the leakage pressure and gas composition of the cylindrical battery can be collected simultaneously. This data provides important information for improving battery design and manufacturing processes, optimizing battery pack layout, and enhancing overall safety, ensuring that the battery can still operate safely and reliably under extreme conditions.

[0096] When thermal runaway occurs violently, the explosion-proof valve of the cylindrical battery will emit flames. In order to avoid damage to the detection devices in the detection component 32, this embodiment also provides a fire extinguishing device 5. Specifically, the fire extinguishing device 5 includes a fire detector 51 and a water storage tank 52. The fire detector 51 is located inside the detection port and is used to detect the fire signal generated when the cylindrical battery undergoes thermal runaway. The water storage tank 52 is located below the mounting frame 1. The top surface of the mounting frame 1 has a through hole 11, which is used to allow the cylindrical battery to fall into the water storage tank 52 when the fire signal is triggered.

[0097] Using the above technical solution, after the cylindrical battery is punctured, the detection component 32 can test the leakage pressure and gas composition of the cylindrical battery during thermal runaway in real time. At the same time, the temperature sensor T can obtain the real-time temperature data of the cylindrical battery surface. When the fire detector 51 detects a flame at the explosion-proof valve port, it indicates that the thermal runaway is quite serious and an explosion may occur at any time. At this time, the fire detector 51 triggers fire extinguishing measures, and the clamping mechanism 2 quickly releases the clamp on the cylindrical battery. At the same time, the drive device 41 also releases the clamp on the puncture needle 42. At this time, the cylindrical battery will fall into the water tank 52 through the through hole 11 on the top surface of the mounting bracket 1 to achieve fire extinguishing operation and prevent the detection component 32 from being damaged by fire caused by the cylindrical battery during the needle puncture test.

[0098] In this embodiment, perfluoroethyl ketone solution can be added to the water storage tank 52 to ensure that the battery is completely submerged after falling, which can extinguish the fire more efficiently.

[0099] Although fire extinguishing measures are provided in the above embodiments, some cylindrical batteries may explode even without a fire due to violent internal reactions during thermal runaway. This may pose certain safety hazards during the testing process. Therefore, the testing device in this embodiment also includes a protective box 6, a mounting bracket 1 is disposed in the protective box 6, a drive device 41 is fixedly disposed on the top surface inside the protective box 6, and a water storage tank 52 and a moving device are disposed on the bottom surface inside the protective box 6.

[0100] With this setup, the entire testing process is carried out in a closed protective box 6. Even if an explosion occurs during the needle penetration test, the protective box 6 can protect the surrounding environment from the explosion.

[0101] In some embodiments, the water storage tank 52 is located on the bottom surface of the mounting frame 1, and the bottom surface of the protective box 6 is also equipped with a pull-out cylinder 8. When a certain amount of cylindrical battery needle penetration tests are completed and the tested cylindrical batteries need to be collected periodically, the water storage tank 52 is pulled out from the mounting frame 1 by the pull-out cylinder 8, which facilitates the collection of the tested cylindrical batteries and puncture needles 42, and also facilitates the replacement of the fire extinguishing solution.

[0102] In some embodiments, in order to facilitate the quick clamping and positioning of the cylindrical battery on the mounting bracket 1, this embodiment also provides a support mechanism 7. The support mechanism 7 can provide the cylindrical battery to be pre-positioned in the initial horizontal direction, and then facilitate the clamping mechanism 2 to perform radial and axial clamping.

[0103] See attached document Figure 5 and 8 As shown, the support mechanism 7 in this embodiment includes a fixed frame 71, a support member 72, a first telescopic element 73, and a second telescopic element 74. The fixed frame 71 is fixedly connected to the mounting frame 1. The first telescopic element 73 is fixedly disposed on the fixed frame 71 and is used to drive the second telescopic element 74 to move horizontally in the length direction of the through hole 11. The second telescopic element 74 is used to drive the support member 72 to pass upward through the through hole 11 and lift the cylindrical battery.

[0104] Using the above technical solution, before initial clamping, the telescopic ends of the second telescopic element 74 and the first telescopic element 73 extend sequentially. At this time, the support member 72 passes vertically upward through the through hole 11, with the upper end of the support member 72 located above the through hole 11. The top surface of the support member 72 has a V-shaped structure. The tester places the cylindrical battery horizontally on the top surface of the two support members 72 and connects the explosion-proof valve and the connection port 33 of the cylindrical battery. Then, the axial clamping assembly 22 and the radial clamping assembly 21 sequentially complete the axial and radial clamping and positioning of the cylindrical battery. After the cylindrical battery is clamped, the telescopic ends of the second telescopic element 74 and the first telescopic element 73 retract sequentially, leaving the area below the through hole 11 in an open environment, which facilitates the falling of the cylindrical battery in the event of a subsequent fire.

[0105] The support mechanism 7 in this embodiment provides initial positioning of the cylindrical battery, and the V-shaped structure design of the support member 72 helps to accurately place the battery. This reduces errors from manual operation, speeds up clamping, and improves work efficiency. After initial positioning, the cylindrical battery is precisely clamped by the axial and radial clamping components 21, ensuring that the battery maintains a stable position during testing and avoiding test errors caused by battery displacement.

[0106] By introducing support mechanism 7, the cylindrical battery clamping and positioning can be completed efficiently and accurately during the process, which not only improves clamping efficiency and accuracy but also simplifies the operation process and reduces the burden of manual operation. The automated support and positioning system ensures battery stability, further improves the safety of the testing process, and provides a guarantee for emergency handling in case of thermal runaway. This design effectively enhances the performance and safety of the testing device, making the entire testing process smoother and more efficient.

[0107] This application also discloses a method for testing the needle penetration of a cylindrical battery, including the following steps:

[0108] S1. Place the cylindrical battery horizontally at the through hole 11 on the top surface of the mounting bracket 1, so that the explosion-proof valve of the cylindrical battery is connected to the connection port 33. The cylindrical battery is axially clamped and positioned by the axial clamping assembly 22, and the cylindrical battery is radially clamped and positioned by the radial clamping assembly 21.

[0109] Between steps S1, the support mechanism 7 can provide precise initial positioning of the cylindrical battery in the horizontal direction. After initial positioning, the cylindrical battery is precisely clamped by the axial and radial clamping components 21, so that the battery maintains a stable position during the test and avoids test errors caused by battery displacement.

[0110] S2. The driving device 41 drives the puncture needle 42 to puncture the cylindrical battery vertically downward. The low melting point alloy on the sealing layer 422 melts at a high temperature of 80-200°C caused by thermal runaway of the battery and fills the gap between the puncture hole and the needle body 421. The solidification accelerator on the sealing layer 422 triggers the solidification mechanism after the sealing layer 422 melts, forming a dense sealing structure in the gap between the puncture hole and the needle body 421.

[0111] S3. When thermal runaway occurs inside the cylindrical battery, the pressure relief port of the explosion-proof valve begins to release high-pressure gas. The pressure sensor 322 in the detection component 32 collects the gas pressure data released by the explosion-proof valve port, the MEMS mass spectrometry chip 323 collects the gas composition released by the explosion-proof valve port, and transmits it to the data processing system for analysis in real time.

[0112] S4. When a fire signal is detected at the explosion-proof valve port by the fire detector 51, the clamping mechanism 2 releases the clamp on the cylindrical battery, and the drive device 41 releases the clamp on the puncture needle 42. The puncture needle 42 falls into the water storage tank 52 along with the cylindrical battery through the through hole 11 to extinguish the fire.

[0113] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A cylindrical battery pin test device, characterized by, The application relates to a cylindrical battery safety detection device, which comprises the following components: a mounting frame; a clamping mechanism fixedly arranged on the mounting frame and used for clamping and fixing a cylindrical battery; a detection mechanism fixedly arranged on the mounting frame and used for connecting with an explosion-proof valve of the cylindrical battery to detect the gas pressure discharged from the explosion-proof valve; a needle-punching mechanism comprising a driving device and a puncture needle, wherein the driving device is used for driving the puncture needle to move to puncture the cylindrical battery, the puncture needle comprises a puncture needle body and a sealing layer arranged on the outer surface of the puncture needle body, the sealing layer comprises a low-melting-point alloy and a solidification promoter, the low-melting-point alloy has a melting point range of 80-150 DEG C and is used for melting and filling the gap between the puncture hole and the puncture needle body at a high temperature of 80-200 DEG C generated by battery thermal runaway, the solidification promoter is uniformly dispersed in the low-melting-point alloy and is used for triggering a solidification mechanism after the sealing layer melts to form a dense sealing structure between the puncture hole and the puncture needle body, and the triggering condition of the solidification promoter is configured to start solidification after the sealing layer is fully filled. The low-melting-point alloy is a bismuth-based alloy layer, which comprises the following components in percentage by mass: the bismuth content is 55-60%, the tin content is 30-38%, the indium content is 5-10%, and the silicon carbide whisker content is 5-10%, the length is 10-20 mu m, the diameter is 0.5-1 mu m, and the silicon carbide whisker is uniformly dispersed in the alloy; the sealing layer has a thickness of 90-110 mu m and is coated on the outer surface of the puncture needle body; and the solidification promoter is one or more of a pressure-sensitive polymer, a curing agent microcapsule and nano-aluminum oxide particles. The puncture needle further comprises a transition layer arranged between the sealing layer and the puncture needle body, the transition layer is used for enhancing the bonding force between the puncture needle body and the sealing layer, and the transition layer is a nickel-based layer with a thickness of 3-8 mu m and a bonding force of greater than or equal to 40 Mpa.

2. The cylindrical battery needle test device of claim 1, wherein: The clamping mechanism comprises a radial clamping assembly and an axial clamping assembly, the radial clamping assembly is symmetrically provided with two groups and is used for clamping the cylindrical battery in the horizontal direction, the axial clamping assembly is used for horizontally pushing one end of the cylindrical battery, the detection mechanism is located at the end of the cylindrical battery away from the axial clamping assembly and comprises a fixed flange and a detection assembly, the fixed flange is fixedly arranged on the top surface of the support frame and is provided with a connecting port, one end of the connecting port is used for sealingly connecting with the explosion-proof valve of the cylindrical battery, the other end is communicated with the detection assembly, and the detection assembly is used for collecting the gas pressure data and gas components discharged from the explosion-proof valve.

3. The cylindrical battery needle test device of claim 2, wherein: The radial clamping assembly comprises a first clamping cylinder and a first clamping piece, the first clamping cylinder is horizontally fixed on the top surface of the mounting frame and is used for driving the first clamping piece to move along the radial direction of the cylindrical battery, and the axial clamping assembly comprises a second clamping cylinder and a second clamping piece, the second clamping cylinder is fixedly arranged on the top surface of the mounting frame and is used for driving the second clamping piece to translate towards the connecting port.

4. The cylindrical battery needle test device of claim 3, wherein: The first clamping piece is provided with a temperature sensor on the side in contact with the cylindrical battery.

5. The cylindrical battery needle test device of claim 2, wherein: The detection assembly comprises a detection cavity, a pressure sensor and a MEMS mass spectrum chip. One end of the detection cavity is communicated with the connecting port, and the other end extends in the axial direction. The inner cavity of the detection cavity comprises a contraction section and an expansion section. The contraction section is located between the connecting port and the expansion section, and the inner diameter gradually decreases from the connecting port to the expansion section. The inner diameter of the expansion section gradually increases from the end of the contraction section away from the connecting port. The pressure sensor is arranged on the inner side of the connecting port and is used to collect the gas pressure data discharged from the explosion-proof valve port. The MEMS mass spectrum chip is arranged at the end of the expansion section away from the contraction section and is used to collect the gas composition discharged from the explosion-proof valve port.

6. The cylindrical battery needle test device of claim 5, wherein: The fire extinguishing device comprises a fire detector and a water storage tank. The fire detector is arranged on the inner side of the detection port and is used to detect the fire signal generated when the cylindrical battery is in thermal runaway. The water storage tank is arranged below the mounting rack, and a through hole is formed in the top surface of the mounting rack. When the fire signal is triggered, the cylindrical battery falls into the water storage tank.

7. The cylindrical battery needle test device of claim 6, wherein: The mounting rack is arranged in the protection box, and the driving device is fixedly arranged on the inner top surface of the protection box. The water storage tank and the moving device are arranged on the inner bottom surface of the protection box. The support mechanism is symmetrically arranged in two groups and is arranged below the two sides of the through hole in the length direction. The support mechanism comprises a fixing frame, a support, a first telescopic element and a second telescopic element. The fixing frame is fixedly connected to the mounting rack. The first telescopic element is fixedly arranged on the fixing frame and is used to drive the second telescopic element to move horizontally in the length direction of the through hole. The second telescopic element is used to drive the support to pass through the through hole upward and lift the cylindrical battery.

8. A cylindrical battery needle puncture test method using the cylindrical battery needle puncture test device according to any one of claims 6 or 7, characterized by, The steps are as follows: S1, horizontally placing the cylindrical battery at the through hole on the top surface of the mounting rack, so that the explosion-proof valve of the cylindrical battery is docked with the connecting port, axially clamping and positioning the cylindrical battery by the axial clamping assembly, and clamping and positioning the cylindrical battery in the radial direction by the radial clamping assembly; S2, vertically downwardly piercing the cylindrical battery by the driving device, melting the low-melting-point alloy on the sealing layer at a high temperature of 80-200 DEG C generated by the battery thermal runaway and filling the gap between the piercing hole and the needle body, triggering the solidification mechanism after the sealing layer is melted by the solidification promoter on the sealing layer, and forming a dense sealing structure between the piercing hole and the needle body; S3, when the thermal runaway occurs in the cylindrical battery, the explosion-proof valve pressure relief port starts to discharge high-pressure gas, the pressure sensor in the detection assembly collects the gas pressure data discharged from the explosion-proof valve port, the MEMS mass spectrum chip collects the gas composition discharged from the explosion-proof valve port, and the data is transmitted to the data processing system in real time for analysis; S4, when the fire detector detects the fire signal from the explosion-proof valve port, the clamping mechanism releases the clamping of the cylindrical battery, the driving device releases the clamping of the piercing needle, and the piercing needle falls into the water storage tank with the cylindrical battery through the through hole for fire extinguishing.

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