Lithium ion battery thermal runaway whole process pressure test method

Abstract

The invention provides a lithium ion battery thermal runaway whole process pressure testing method, and relates to the technical field of lithium ion battery testing, and the method comprises the steps: determining the required number of standby tanks based on the total gas production amount during the thermal runaway of a lithium ion battery to be tested; sequentially assembling the base tank body, the standby tank bodies with the required number and the cover plate to form a current test tank body; placing the lithium ion battery to be tested into the current test tank body, then heating the lithium ion battery to be tested, continuously monitoring the real-time pressure in the current test tank body, and further processing to obtain the pressure change of the lithium ion battery to be tested in the whole thermal runaway process. The method has the beneficial effects that the sensitivity and accuracy of pressure data in the initial stage of thermal runaway are ensured; and the problems that the pressure suddenly rises and exceeds the equipment range due to insufficient volume during large-scale gas production in the later period are solved, and non-breakpoint acquisition of pressure data in the whole process from thermal runaway triggering to a stable stage is really realized.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery testing technology, and in particular to a pressure testing method for the entire process of thermal runaway in lithium-ion batteries. Background Technology

[0002] Prismatic lithium iron phosphate batteries, with their superior safety, cycle life, and cost advantages, are widely used in many important fields such as new energy electric vehicles, electric commercial vehicles, large-scale energy storage power stations, and portable electronic devices, becoming a core support for promoting the electrification of transportation and the intelligentization of energy storage. At the same time, with the continuous expansion of application scenarios, the market is placing increasingly stringent requirements on the energy density, operating rate, and application scale of lithium-ion batteries. The stable operation of large-scale battery packs under high-rate charge and discharge conditions has become a focus of industry attention.

[0003] However, under high-rate operation, large-scale lithium-ion batteries experience a dramatic increase in electrode reaction rates, generating substantial Joule heat and reaction heat. If the cooling system cannot dissipate this heat in time, the battery temperature will rise rapidly, leading to a heat accumulation effect. The electrochemical performance of lithium-ion batteries is extremely sensitive to temperature. High temperatures not only cause rapid capacity decay and a significant reduction in cycle life, but more seriously, when the temperature exceeds a critical threshold, a series of violent side reactions will occur inside the battery, including electrolyte decomposition and electrode material structural collapse, triggering thermal runaway. During thermal runaway, large amounts of flammable and explosive gases (such as hydrogen, methane, and carbon monoxide) are generated. These gases are not only highly corrosive but can also accumulate in confined spaces to form explosive mixtures. If they encounter an ignition source, they can cause explosions, fires, and other serious safety accidents, posing a significant threat to human life and property. Therefore, the gas generation characteristics and pressure change patterns during the thermal runaway process of lithium-ion batteries have gradually become a core research hotspot in the field of new energy safety.

[0004] To mitigate or even eliminate the hazards of thermal runaway in lithium-ion batteries, the industry urgently needs to design efficient and reliable pressure relief buffer measures and accurate early warning systems. Whether it's optimizing the parameters of the pressure relief structure or scientifically setting the warning threshold, the core prerequisite is a comprehensive and accurate understanding of the gas production patterns and pressure change characteristics of the target battery during operation, especially throughout the entire thermal runaway process, including complete data on the very early, minute gas production stage, the mid-stage of accelerated gas production, and the later, stable gas production stage.

[0005] Currently, most methods for testing the thermal runaway pressure of lithium-ion batteries use fixed-volume test tanks. However, in actual testing, this method has significant technical bottlenecks: In the very early stages of thermal runaway, the amount of gas produced by the battery is extremely small. If the test tank volume is too large, the small amount of gas produced cannot create an effective pressure fluctuation within the tank that can be accurately captured by the sensor, leading to distortion or loss of pressure data in the very early stages. On the other hand, if a tank with too small a volume is selected to meet the testing requirements in the very early stages, the amount of gas produced increases sharply as the thermal runaway progresses, and the pressure inside the tank will soar in a short period of time. This may not only exceed the range of the pressure sensor, causing the test to be interrupted, but may also cause the test tank seal to fail or even burst due to excessive pressure, resulting in safety risks and equipment damage.

[0006] Therefore, how to match the gas generation characteristics of the entire thermal runaway process and provide a test scheme with flexible volume adjustment has become a key technical problem that urgently needs to be solved in the field of thermal runaway pressure testing of lithium-ion batteries. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a pressure testing method for the entire thermal runaway process of lithium-ion batteries. The method employs a variable-volume test tank, which includes a base tank with an open top, several spare tanks with open ends, and a cover plate. The method includes: Step S1: Determine the required number of backup tanks based on the total amount of gas generated during thermal runaway of the lithium-ion battery under test; Step S2: Assemble the base tank, the required number of spare tanks, and the cover plate in sequence to form the current test tank; Step S3: Place the lithium-ion battery to be tested into the current test container, then heat the lithium-ion battery to be tested, and continuously monitor the real-time pressure in the current test container to obtain the pressure change of the lithium-ion battery during the entire thermal runaway process.

[0008] Preferably, before performing step S1, the method further includes testing to obtain the total gas production, including: Step A1: Calculate the estimated gas production based on the capacity of the lithium-ion battery to be tested; Step A2: The lithium-ion battery to be tested is placed in a large sealed container for thermal runaway testing to obtain the actual total gas production, wherein the volume of the large sealed container is greater than the estimated gas production.

[0009] Preferably, in step S1, the required quantity is determined according to the following formula:

[0010] in, The required quantity. The total gas production is [the total amount of gas produced]. 1 is the required volume of the current test tank. One standard atmosphere To ensure the safe pressure resistance of the large sealed tank, The volume of the base tank is... The volume of the spare tank.

[0011] Preferably, the top opening of the base tank is provided with an external thread, and one end opening of the spare tank is provided with an internal thread, while the other end opening is provided with an external thread. Multiple threaded holes are provided at the top opening of the base tank, at the opening of the spare tank with the external thread, and on the cover plate. In step S2, the base tank and the spare tank are first connected by threads, and the spare tanks are connected to each other by threads. Then, the cover plate is assembled to the top opening by passing the corresponding bolts through the threaded holes to form the current test tank.

[0012] Preferably, the ends of the base tank and the spare tank with the threaded holes are also provided with gasket openings; In step S2, before assembling the base tank with the spare tank, the spare tank with the spare tank and the cover plate, the gaskets are placed into the corresponding gasket openings. The gasket is a fluorinated rubber ring.

[0013] Preferably, the cover plate integrates an inflation port, a pressure pipe interface, and a vent; before performing step S3, a pressure holding test is also performed on the current test tank. A pressure sensor is installed on the pressure pipeline interface. Nitrogen gas is introduced into the current test tank through the gas inlet. The internal gas pressure of the current test tank collected by the pressure sensor is then monitored. If the internal gas pressure does not drop within a certain period of time, it indicates that the pressure holding test has passed. Then, the current test tank is vented to normal pressure through the gas outlet before proceeding to step S3.

[0014] Preferably, the cover plate integrates an electrode post and a pressure pipe interface; step S3 further includes: A heating element is installed inside the current test tank to contact the lithium-ion battery. The heating element is electrically connected to the electrode post, thereby supplying power to the heating element through the electrode post to heat the lithium-ion battery under test. The real-time pressure is continuously monitored by a pressure sensor installed at the pressure pipeline interface.

[0015] Preferably, in step S3, the cover plate integrates a thermocouple interface for connecting a thermocouple; Step S3 also includes continuously monitoring the real-time temperature inside the current test tank using the thermocouple.

[0016] Preferably, in step S3, before placing the lithium-ion battery to be tested into the current test container, the safety valve or top cover of the lithium-ion battery to be tested is adjusted to a non-sealed state.

[0017] Preferably, in step S3, the internal pressure of the lithium-ion battery under test during the entire thermal runaway process is obtained according to the following formula to characterize the pressure change:

[0018] in, The internal pressure of the battery. The real-time pressure, The volume of the internal blank area of ​​the lithium-ion battery. The volume of the current test tank.

[0019] The above technical solution has the following advantages or beneficial effects: 1) By determining the required number of backup tanks based on the total amount of gas generated during thermal runaway of the lithium-ion battery under test, the volume of the current test tank after assembly can be dynamically adapted to the gas generation requirements of the lithium-ion battery throughout its entire life cycle. Compared with traditional fixed-volume tanks, this avoids the problem of weak pressure fluctuations and inaccurate sensor capture due to excessive volume during the very early stage of micro-gas generation, ensuring the sensitivity and accuracy of pressure data in the initial stage of thermal runaway. It also solves the problem of pressure surges and exceeding the equipment range due to insufficient volume during the later stage of large-volume gas generation, providing sufficient space for complete monitoring of pressure changes in the middle and later stages of thermal runaway, and truly realizing uninterrupted acquisition of pressure data throughout the entire process from thermal runaway triggering to the stabilization stage. 2) The variable volume test tank adopts a modular assembly structure of base tank, spare tank and cover plate. The assembly process is simple and convenient. The number of spare tanks can be flexibly adjusted according to the different specifications and capacities of the batteries to be tested. There is no need to customize special test equipment for each type of battery, which greatly improves the versatility of the test device and reduces the equipment investment and maintenance costs. At the same time, since the test volume is matched with the total gas production, it can effectively avoid safety risks such as tank seal failure and explosion caused by abnormal pressure rise. Combined with continuous pressure monitoring, it further provides double protection for the safety of test personnel and equipment. Attached Figure Description

[0020] Figure 1A schematic diagram of the structure of the variable volume test tank in a preferred embodiment of the present invention; Figure 2 A schematic diagram of the structure of the base tank in a preferred embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the spare tank in a preferred embodiment of the present invention; Figure 4 A flowchart illustrating a pressure test method for the entire process of thermal runaway of a lithium-ion battery, as described in a preferred embodiment of the present invention. Figure 5 In a preferred embodiment of the present invention, a flowchart illustrating the process of testing and obtaining the total gas production is provided. Figure 6 A connection diagram for pressure holding test of variable volume test tank in a preferred embodiment of the present invention; Figure 7 This is a schematic diagram of the test results for Embodiment 1 of the present invention; In the diagram: 1. Base tank; 11. Threaded hole of base tank; 12. Gasket opening of base tank; 13. External thread of base tank; 2. Spare tank; 21. External thread of spare tank; 22. Threaded hole of spare tank; 23. Gasket opening of spare tank; 24. Internal thread; 3. Cover plate; 31. Pressure pipeline interface; 32. Polar post; 33. Thermocouple interface; 4. Pressure sensor; 5. Nitrogen cylinder; 6. Bolt; 7. Vent valve. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment; other embodiments that conform to the spirit of the present invention may also fall within the scope of the present invention.

[0022] In a preferred embodiment of the present invention, based on the above-mentioned problems existing in the prior art, a pressure testing method for the entire process of thermal runaway of lithium-ion batteries is provided. The method uses a variable volume test tank for testing, which fundamentally solves the technical bottleneck that traditional fixed volume test devices are difficult to adapt to the gas generation characteristics of the entire thermal runaway stage, and greatly improves the accuracy and reliability of pressure testing.

[0023] Specifically, such as Figure 1 As shown, the variable volume test tank has a modular assembly structure, mainly consisting of three core components: first, a base tank 1 with an open top, which serves as the basic load-bearing unit of the test tank and provides stable bottom support for testing; second, several spare tanks 2 with open ends, which serve as the core module for volume expansion and can be flexibly added or removed according to actual gas production needs; and third, a cover plate 3, which serves as the sealing and functional integration unit of the tank, realizing the sealing of the tank and the installation and fixing of test accessories.

[0024] Among them, such as Figure 2 As shown, the aforementioned base tank 1 is preferably a semi-enclosed metal tank, with external threads 13 machined around the open opening to provide a mechanical basis for connection with the spare tank 2; 12 threaded holes 11 are evenly distributed around its top perimeter, which can be used to tightly fix the cover plate 3 with bolts 6 when the test volume requirement can be met by using only the base tank 1; at the same time, a special gasket opening 12 is provided to place a gasket to enhance the interface sealing.

[0025] like Figure 3 As shown, the aforementioned spare tank 2 is made of metal with openings at the top and bottom. Its upper part has the same structure as the top of the base tank 1, and is also provided with external threads 21, 12 threaded holes 22 and gasket openings 23, which can achieve a stable connection with the upper spare tank 2 or the cover plate 3. The lower open part is only machined with internal threads 24, which can accurately mesh with the external threads of the base tank 1 or the lower spare tank 2, and achieve rapid expansion of volume through threaded connection.

[0026] like Figure 1 As shown, the cover plate 3 is a key component of the functional integration. Its surface is machined with 12 threaded holes that correspond perfectly to the threaded holes of the base tank 1 and the spare tank 2, ensuring the sealing reliability after assembly.

[0027] Based on the structural advantages of the aforementioned variable volume test tank, such as Figure 4 As shown, the specific process of this test method includes: Step S1: Determine the required number of spare tanks based on the total amount of gas generated during thermal runaway of the lithium-ion battery under test; Step S2: Assemble the base tank, the required number of spare tanks, and the cover plate in sequence to form the current test tank; Step S3: Place the lithium-ion battery to be tested into the current test container, then heat the lithium-ion battery to be tested, and continuously monitor the real-time pressure in the current test container to obtain the pressure change of the lithium-ion battery during the entire thermal runaway process.

[0028] Specifically, traditional fixed-volume tanks often experience problems such as early pressure monitoring failure or later pressure exceeding limits because they cannot adjust the volume according to the total gas production. This method avoids this problem from the source by matching the total gas production with the volume.

[0029] To ensure the accuracy of the total gas production, such as Figure 5 As shown, before performing step S1, the total gas production is obtained by testing, including: Step A1: Calculate the estimated gas production based on the capacity of the lithium-ion battery to be tested. Step A2: Place the lithium-ion battery to be tested into a large sealed container for thermal runaway testing to obtain the actual total gas production. The volume of the large sealed container is greater than the estimated gas production.

[0030] Specifically, the estimated gas production rate is calculated based on the relationship between the capacity of the lithium-ion battery and the estimated gas production rate, such as 2.5 L / Ah, meaning that the theoretical gas production rate of a lithium-ion battery per ampere-hour is 2.5 L. This estimated gas production rate provides a reference for subsequent testing. The battery is then placed in a large, sealed container with a volume greater than the estimated gas production rate for thermal runaway testing to obtain the actual total gas production, thus avoiding discrepancies between theoretical calculations and actual conditions.

[0031] When determining the total tank volume, the required volume Vcan of the current test tank is calculated based on the safe pressure resistance P of the large sealed tank. The calculation formula is Vcan = V × 1 atm / P. This formula converts the gas production rate by the ratio of standard atmospheric pressure to the safe pressure resistance, ensuring that the tank pressure does not exceed the safe threshold during the test and avoiding a decrease in pressure sensitivity due to excessive volume. The final required number N of backup tanks 2 is determined based on the volume V1 of a single backup tank and the volume V2 of the base tank, i.e., the required number is determined according to the following formula:

[0032] in, For the required quantity, Total gas production 1 is the required volume of the current test tank. One standard atmosphere For large, sealed tanks, the tank body must be pressure-resistant. The volume of the base tank. This refers to the volume of the spare tank.

[0033] This calculation ensures that the total volume of the combined tank can fully meet the gas production requirements of the entire thermal runaway process, covering both the very early stage of trace gas production and the later stage of large-scale gas production.

[0034] After determining the required quantity N of spare tanks 2, first, place the gaskets into the gasket openings 12 of the base tank 1 and the gasket openings 23 of each spare tank 2. Then, precisely connect the internal threads of the required number of spare tanks 2 to the external threads of the base tank 1. If multiple spare tanks 2 are needed, they are assembled by sequentially connecting them with their internal and external threads. This threaded connection method not only facilitates assembly but also ensures the sealing of the interface. Compared to traditional welded or fixed-structure tanks, this modular assembly method allows for flexible adjustment of the volume according to the gas production characteristics of different batteries, significantly improving the versatility of the testing device and reducing the investment cost of dedicated equipment.

[0035] The gasket is preferably a fluorinated rubber ring, but it can also be a gasket made of other materials. As long as it has excellent high temperature resistance, can adapt to the temperature rise during thermal runaway, and can melt to relieve pressure in extreme cases (such as combustion or deflagration), it can provide a double guarantee of sealing and safe pressure relief.

[0036] Considering that sealing performance is a core prerequisite for pressure testing, any leakage in the tank will directly lead to distorted pressure data. Therefore, after the current test tank is assembled, a pressure holding test is also required to ensure the tank's airtightness. The cover plate 3 integrates an inflation port (not shown in the figure), a pressure pipe interface 31, and a vent (not shown in the figure). Before executing step S3, such as... Figure 6 As shown, it also includes performing a pressure holding test on the current test tank: A pressure sensor 4 is installed on the pressure pipeline interface 31, and a nitrogen cylinder 5 is connected through the air filling port to introduce nitrogen into the current test tank. Then, the internal air pressure of the current test tank collected by the pressure sensor 4 is monitored. If the internal air pressure does not drop within a certain period of time, it indicates that the pressure holding test has passed. Then, the current test tank is vented to normal pressure through the venting valve 7 connected to the venting port, and step S3 is executed.

[0037] The aforementioned duration is typically one minute, but is not a fixed limit. After successful pressure holding, nitrogen cylinder 5 is closed, and the internal pressure of the tank is released to atmospheric pressure, creating a stable initial pressure environment for subsequent tests. This pressure holding process can proactively identify potential leaks in threaded connections, gasket seals, and other components, ensuring the reliability of pressure data before testing and avoiding test errors caused by sealing issues.

[0038] After the pressure holding test is completed, the lithium-ion battery under test can be tested for pressure changes throughout the entire thermal runaway process. The cover plate 3 integrates electrode posts 32 and pressure pipe interfaces 31. Step S3 also includes: A heating element that contacts the lithium-ion battery is installed inside the current test tank. The heating element is electrically connected to the electrode post 32, thereby supplying power to the heating element through the electrode post 32 to heat the lithium-ion battery under test. The real-time pressure is continuously monitored by the pressure sensor 5 installed at the pressure pipeline interface 31.

[0039] In a preferred embodiment of the present invention, in step S3, the cover plate 3 is integrated with a thermocouple interface 33 for connecting a thermocouple. Step S3 also includes continuously monitoring the real-time temperature inside the current test tank using thermocouples.

[0040] In a preferred embodiment of the present invention, before placing the lithium-ion battery to be tested into the current test container in step S3, the safety valve or top cover of the lithium-ion battery to be tested is adjusted to a non-sealed state to ensure that the gas generated by the thermal runaway of the battery can completely enter the container and avoid the leakage of gas generation data caused by the battery being trapped inside.

[0041] After the test begins, power is supplied to the heating element via electrode post 32 to heat the battery under test and trigger thermal runaway. Simultaneously, real-time pressure and temperature data within the tank are collected. To accurately characterize the pressure changes inside the battery, based on the total tank volume and the battery's internal structural parameters, the internal pressure of the lithium-ion battery under test during the entire thermal runaway process is obtained using the following formula to characterize the pressure changes:

[0042] in, For the internal pressure of the battery, For real-time pressure, This refers to the volume of the internal blank area of ​​a lithium-ion battery. This represents the volume of the current test tank.

[0043] This formula enables accurate conversion between real-time pressure inside the tank and internal pressure inside the battery, solving the technical problem that traditional tests can only obtain external environmental pressure and cannot directly reflect the internal pressure state of the battery, thus providing more direct core data for the study of thermal runaway mechanisms.

[0044] Example 1 Taking the 46120 ternary lithium battery as an example, this lithium-ion battery is heated at 400W, and the present invention is described in detail. The method is established in four steps: Step 1: Based on the total gas production during the thermal runaway test of the lithium-ion battery under test in a 140L tank, it is determined that the required number of spare tanks 2 is 2, with a final total volume of 10L. Step 2: Place the fluorinated rubber gasket into the gasket opening 12 of the base tank and connect the internal thread 21 of the spare tank to the external thread 13 of the base tank. Step 3: Place the gasket into the gasket opening 23 on the assembled spare tank, and secure the cover plate 3 by bolting through the threaded hole. Open the nitrogen cylinder 5 and purge air into the sealed tank, observing whether the reading on the paperless recorder output by the pressure sensor 4 drops within 1 minute. After confirming that there are no issues with pressure maintenance, close the nitrogen cylinder 5 and release the internal pressure of the tank to atmospheric pressure.

[0045] Step four: Place the known battery to be tested into the assembled container, and connect the electrode post 32, thermocouple interface 33, and pressure pipe interface 31 at the top cover according to the test items; after the experiment begins, obtain the real-time pressure value inside the container during the experiment, and infer the internal pressure of the battery based on this, and finally plot the gas production changes and temperature change patterns of the entire thermal runaway process of the lithium-ion battery under test as follows. Figure 7 As shown.

[0046] In summary, the variable volume design completely solves the dual problems of insufficient early-stage sensitivity and excessive pressure in later stages associated with fixed-volume tanks. The modular assembly structure improves equipment versatility and reduces testing costs. The process design, which includes actual measurement of total gas production, precise volume calculation, and rigorous pressure holding testing, ensures the accuracy and reliability of pressure data. Furthermore, the scientific conversion of internal battery pressure provides core parameters with greater reference value for thermal runaway safety protection design. Whether for high-power batteries in electric vehicles or large-capacity battery packs in energy storage power stations, this method can achieve accurate pressure testing throughout the entire thermal runaway process, providing strong technical support for the design of lithium battery pressure relief measures and the development of early warning systems.

[0047] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present invention.

Claims

1. A pressure testing method for the entire process of thermal runaway in a lithium-ion battery, characterized in that, The test is conducted using a variable-volume test tank, which includes a base tank with an open top, several spare tanks with open ends, and a cover plate; the method includes: Step S1: Determine the required number of backup tanks based on the total amount of gas generated during thermal runaway of the lithium-ion battery under test; Step S2: Assemble the base tank, the required number of spare tanks, and the cover plate in sequence to form the current test tank; Step S3: Place the lithium-ion battery to be tested into the current test container, then heat the lithium-ion battery to be tested, and continuously monitor the real-time pressure in the current test container to obtain the pressure change of the lithium-ion battery during the entire thermal runaway process.

2. The method for pressure testing the entire process of thermal runaway in a lithium-ion battery according to claim 1, characterized in that, Before performing step S1, the method further includes testing to obtain the total gas production, including: Step A1: Calculate the estimated gas production based on the capacity of the lithium-ion battery to be tested; Step A2: The lithium-ion battery to be tested is placed in a large sealed container for thermal runaway testing to obtain the actual total gas production, wherein the volume of the large sealed container is greater than the estimated gas production.

3. The method for pressure testing the entire process of thermal runaway in a lithium-ion battery according to claim 2, characterized in that, In step S1, the required quantity is determined according to the following formula: ； in, The required quantity. The total gas production is [the amount of gas produced]. 1 is the required volume of the current test tank. One standard atmosphere To ensure the safe pressure resistance of the large sealed tank, The volume of the base tank is... The volume of the spare tank.

4. The pressure test method for the entire process of thermal runaway of a lithium-ion battery according to claim 1, characterized in that, The top opening of the base tank is provided with an external thread, and the opening at one end of the spare tank is provided with an internal thread, while the opening at the other end is provided with an external thread. Multiple threaded holes are provided at the top opening of the base tank, at the opening of the spare tank with the external thread, and on the cover plate. In step S2, the base tank and the spare tank are first connected by threads, and the spare tanks are connected to each other by threads. Then, the cover plate is assembled to the top opening by passing the corresponding bolts through the threaded holes to form the current test tank.

5. The pressure test method for the entire process of thermal runaway of a lithium-ion battery according to claim 4, characterized in that, The base tank and the spare tank are also provided with gasket openings at the ends where the threaded holes are opened; In step S2, before assembling the base tank with the spare tank, the spare tank with the spare tank and the cover plate, the gaskets are placed into the corresponding gasket openings. The gasket is a fluorinated rubber ring.

6. The method for pressure testing the entire process of thermal runaway in a lithium-ion battery according to claim 1, characterized in that, The cover plate integrates an inflation port, a pressure pipe interface, and a vent; before performing step S3, a pressure holding test is also performed on the current test tank. A pressure sensor is installed on the pressure pipeline interface. Nitrogen gas is introduced into the current test tank through the gas inlet. The internal gas pressure of the current test tank collected by the pressure sensor is then monitored. If the internal gas pressure does not drop within a certain period of time, it indicates that the pressure holding test has passed. Then, the current test tank is vented to normal pressure through the gas outlet before proceeding to step S3.

7. The method for pressure testing the entire process of thermal runaway in a lithium-ion battery according to claim 1, characterized in that, The cover plate integrates an electrode post and a pressure pipe interface; step S3 further includes: A heating element is installed inside the current test tank to contact the lithium-ion battery. The heating element is electrically connected to the electrode post, thereby supplying power to the heating element through the electrode post to heat the lithium-ion battery under test. The real-time pressure is continuously monitored by a pressure sensor installed at the pressure pipeline interface.

8. The method for pressure testing the entire process of thermal runaway in a lithium-ion battery according to claim 1, characterized in that, In step S3, the cover plate is integrated with a thermocouple interface for connecting a thermocouple; Step S3 also includes continuously monitoring the real-time temperature inside the current test tank using the thermocouple.

9. The method for pressure testing the entire process of thermal runaway in a lithium-ion battery according to claim 1, characterized in that, In step S3, before placing the lithium-ion battery to be tested into the current test container, the safety valve or top cover of the lithium-ion battery to be tested is adjusted to a non-sealed state.

10. The method for pressure testing the entire process of thermal runaway in a lithium-ion battery according to claim 1, characterized in that, In step S3, the internal pressure of the lithium-ion battery under test during the entire thermal runaway process is obtained according to the following formula to characterize the pressure change: ； in, The internal pressure of the battery. The real-time pressure, The volume of the internal blank area of ​​the lithium-ion battery. The volume of the current test tank.

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