Device and method for testing thermal runaway of cylindrical lithium battery

Abstract

The invention discloses a device and a method for testing thermal runaway of a cylindrical lithium battery, which belong to the technical field of lithium batteries, and are characterized in that one battery is accommodated by using three cavities, and the cavities are respectively and independently closed; each part of the battery can be respectively tested to determine the energy / substance spraying position and the ratio of the energy / substance sprayed by each part of the battery. The measurement of the energy and the substance of the sprayed substance during the thermal runaway of the single battery can be rapidly completed, the spraying energy and the spraying substance of each position of the battery can be accurately measured, and the key guiding effect on the design of the battery and the PACK is achieved. The device is simple in structure, small in size and convenient to carry compared with a traditional measuring instrument; and moreover, the compatibility is high, and the test of various thermal runaway occurrence scenes such as thermal abuse, mechanical damage and internal short circuit can be compatible. According to the invention, the test data is rich, and various data such as energy released by thermal runaway, energy proportions at different positions, material composition, volume, battery internal change and the like can be obtained according to the measurement results.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and in particular relates to a device and method for testing thermal runaway of cylindrical lithium batteries. Background Art

[0002] With the application of lithium batteries in aerospace, travel, and home appliances, their safety issues are related to the development of the entire society. Thermal runaway of a single lithium battery will trigger thermal runaway of other batteries in the battery pack, causing a serious chain reaction. Therefore, exploring the total energy released during thermal runaway of the battery and the distribution of the thermal runaway energy in the overall battery system, as well as the thermal decoupling of battery materials during thermal runaway, can play a key guiding role in the design of battery cells and PACKs, and is of great significance to overall safety.

[0003] At present, the test methods / devices for thermal runaway of lithium batteries are highly targeted, with poor measurement compatibility, single measurement results and low efficiency. Conventional calorimeters The calorimeters currently available measure the conditions for the occurrence of battery thermal runaway, thermal runaway dynamics and the total energy of thermal runaway ejection. A single test may even take 1 to 2 days, with low measurement efficiency. It is very difficult to quickly test a large number of batteries. Other measurement methods can only measure the volume or composition of the material ejected by the battery when it is hot, and cannot derive the energy / material ejection location and its proportion. Summary of the invention

[0004] The present invention provides a device and method for testing thermal runaway of a cylindrical lithium battery, which uses three closed cavities to test and study different parts of the battery, so as to solve the deficiencies described in the above-mentioned prior art.

[0005] The technical solution adopted by the present invention is: A device for testing thermal runaway of a cylindrical lithium battery comprises a battery compartment structure, a positive electrode injection cavity structure, a negative electrode injection cavity structure, a data acquisition structure and a battery thermal runaway structure, wherein the positive electrode injection cavity structure and the negative electrode injection cavity structure are arranged on both sides of the battery compartment structure, and the positive electrode injection cavity of the positive electrode injection cavity structure, the negative electrode injection cavity of the negative electrode injection cavity structure and the battery cavity of the battery compartment structure are connected to form a complete battery cavity, the complete battery cavity is divided into three closed chambers by the installed battery, and there is no heat transfer between the positive electrode injection cavity, the negative electrode injection cavity and the battery cavity; the battery thermal runaway structure corresponds to the battery cavity to trigger the installed battery to have thermal runaway; the positive electrode injection cavity and the negative electrode injection cavity are both provided with an exhaust structure; and the positive electrode injection cavity, the negative electrode injection cavity and the battery cavity are all provided with a data acquisition structure, and the data acquisition structure comprises a pressure sensor and a temperature sensor. The length of the battery cavity is smaller than the length of the battery. After the battery is assembled, the positive and negative ends of the battery are exposed in the battery cavity. The three parts of the battery are separated separately by the positive electrode injection cavity and the negative electrode injection cavity, and the three cavities are isolated from each other, so that heat transfer and communication of gases or substances do not occur.

[0006] As a preferred solution of the present invention, the battery compartment structure includes a battery compartment body and a plug. The battery compartment body is provided with a battery cavity. Plugs are provided at both end openings of the battery cavity. The plugs are provided with battery clearance holes, which are connected to the battery cavity. There is a gap between the inner wall of the battery cavity and the installed battery, which serves as a accommodating cavity for thermal runaway of the battery section. The inner diameter of the battery clearance hole is slightly larger than the outer diameter of the installed battery, which reduces the gap between the two and allows only the battery end to pass through and enter the corresponding positive electrode injection cavity or negative electrode injection cavity, and the gas and substances generated after thermal runaway will not pass through.

[0007] As a preferred embodiment of the present invention, the thermal runaway structure is a heating structure or a puncture structure. The heating structure can be directly built into the battery cavity, using a heating wire, a heating plate or a metal magnesium rod, etc.; or an external heater can be used to directly heat the battery compartment; when using the puncture structure, a steel needle with an internal temperature sensor is directly used to puncture the battery, and the internal temperature change of the battery during the puncture test is measured by the internal sensor of the steel needle.

[0008] As a preferred solution of the present invention, the positive electrode injection chamber structure includes a positive electrode injection tube, a positive electrode injection chamber is arranged in the positive electrode injection tube, the end of the positive electrode injection chamber close to the battery compartment body is connected to the plug, and a heat insulating member is arranged at the connection between the positive electrode injection chamber and the plug; the positive electrode injection chamber is communicated with the battery clearance hole; the end of the positive electrode injection chamber away from the battery compartment body is closed; the positive electrode injection chamber is provided with an exhaust structure; and an injection capture structure is arranged in the positive electrode injection chamber. After the thermal runaway ends, the exhaust structure can discharge the gas in the positive electrode injection chamber for analyzing the components in the gas, and the injection capture structure is used to capture the heat and solid particles of the thermal runaway injection.

[0009] As a preferred solution of the present invention, the negative electrode injection chamber structure includes a negative electrode injection tube, a negative electrode injection chamber is arranged in the negative electrode injection tube, the end of the negative electrode injection chamber close to the battery compartment body is connected to the plug, and a heat insulating member is arranged at the connection between the negative electrode injection chamber and the plug; the negative electrode injection chamber is communicated with the battery clearance hole; the end of the negative electrode injection chamber away from the battery compartment body is closed; the negative electrode injection chamber is provided with an exhaust structure; and a spray capture structure is arranged in the negative electrode injection chamber. The heat insulating member used is a heat insulating ceramic ring to thermally isolate the battery cavity from the negative electrode injection chamber.

[0010] As a preferred solution of the present invention, the jet capture structure includes a central metal rod, a plurality of hollow baffles and a grid cage, the central metal rod is arranged along the axis direction of the battery compartment body, the plurality of hollow baffles and the grid cage are penetrated on the central metal rod, and the grid cage is located at one end of the central metal rod away from the battery compartment body. The central metal rod supports the hollow baffles and the grid cage on the one hand, and collects the heat of the jet on the other hand. The hollow baffle can reduce the speed of the battery jet and extinguish the fire; the hollow baffle and the grid cage together realize the collection of the jet, which is convenient for the subsequent collection and weighing of solid matter.

[0011] As a preferred solution of the present invention, the end of the central metal rod close to the battery compartment body is a conical end, and the diameter of the end surface of the conical end close to the battery compartment body is larger than the diameter of the end surface of the conical end away from the battery compartment body. The conical structure can abut against the end of the battery, making it easier for the hollow baffle and the grid to collect and measure the ejected matter.

[0012] As a preferred solution of the present invention, the battery compartment body includes battery sub-compartments, which are detachably assembled together. The assembled structure is convenient for opening and removing batteries and battery residues, and a sealing structure is provided at the assembled location to seal the battery cavity.

[0013] The present invention also provides a method for testing thermal runaway of a cylindrical lithium battery, comprising the following steps: Weighing the battery to be tested; the battery to be tested can be in any SOC state, and obtaining the initial battery weight; Assemble the battery to be tested into the above-mentioned device for testing thermal runaway of cylindrical lithium batteries; The shell of the battery to be tested is placed in the battery cavity, the positive terminal of the battery to be tested is placed in the positive electrode injection cavity, and the negative terminal of the battery to be tested is placed in the negative electrode injection cavity; during assembly, the battery cavity, the positive electrode injection cavity, and the negative electrode injection cavity are independent of each other, and no heat is transferred between them, and the gas and substances generated by thermal runaway do not escape from their respective cavities; Trigger thermal runaway of the battery under test; Using a battery thermal runaway structure to trigger thermal runaway of the battery to be tested, wherein the battery thermal runaway structure is a heating structure or a puncture structure; Analyze the thermal runaway injection of the battery under test in the battery cavity, positive electrode injection cavity and negative electrode injection cavity; For the battery cavity: Determine the volume of gas generated by thermal runaway at the current part of the battery under test through a pressure sensor; Determine the energy generated by thermal runaway of the current part of the battery under test through a temperature sensor; Weigh the solid matter in the battery cavity; For the positive injection chamber: Determine the volume of gas generated by thermal runaway at the current part of the battery under test through a pressure sensor; Determine the energy generated by thermal runaway of the current part of the battery under test through a temperature sensor; Recover and analyze the gas composition of the gas in the cathode injection chamber; Weighing the solid matter in the cathode injection chamber; For the cathode injection chamber: Determine the volume of gas generated by thermal runaway at the current part of the battery under test through a pressure sensor; Determine the energy generated by thermal runaway of the current part of the battery under test through a temperature sensor; Recover and analyze the gas composition of the gas in the negative electrode injection chamber; Weighing the solid matter in the negative electrode injection chamber; And weigh the battery remains.

[0014] The total energy of the jet is obtained by summing up the energy of each part, and then the proportion of the jet energy of each part in the total energy is obtained; By comparing the weight of solid matter in each part with the weight of battery debris, we can obtain the proportion of the material ejected from each part in the battery debris; The gas composition produced by the injection can be obtained by recovering and analyzing the gas in the positive and negative injection chambers.

[0015] As a preferred solution of the present invention, when triggering the thermal runaway of the battery to be tested, an X-ray tomography scanner is configured outside the battery compartment. The X-ray tomography scanner is used to observe the changes in the entire thermal runaway process inside the battery to be tested, so as to determine the process of thermal decoupling; The present invention uses three cavities to accommodate a battery, and each cavity is independently closed. After the thermal runaway of the battery is triggered, each part of the battery can be tested separately to determine the energy / matter injection position and proportion of each part of the battery.

[0016] The present invention can quickly complete the measurement of the energy and matter of ejected materials during thermal runaway of a single battery. Compared with the measurement methods / devices currently available on the market that achieve the same effect, the cost is reduced and the efficiency is improved. It can also accurately measure the injection energy and injection material at each position of the battery, which plays a key guiding role in the design of batteries and PACKs. The present invention has a simple structure and a small size, and is easy to carry compared to traditional measuring instruments; it also has strong compatibility and can be compatible with the testing of various thermal runaway scenarios such as thermal abuse, mechanical damage, and internal short circuit.

[0017] In addition, the test data of the present invention is rich, and the measurement results can measure various data such as the energy released by thermal runaway, the energy proportion at different positions, the material composition, the volume, the internal changes of the battery, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a structural schematic diagram of the present invention.

[0020] Figure 2 It is a cross-sectional view of the present invention.

[0021] Figure 3 It is an exploded view of the present invention. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example: A device for testing thermal runaway of cylindrical lithium batteries, comprising a battery compartment structure 1, a positive electrode injection cavity structure 2, a negative electrode injection cavity structure 3, a data acquisition structure and a battery thermal runaway structure. The data acquisition structure comprises a pressure sensor and a temperature sensor, and the temperature sensor can use a K-type thermocouple to measure the temperature rise of each component and cavity. The positive electrode injection cavity structure 2 and the negative electrode injection cavity structure 3 are symmetrically arranged on both sides of the battery compartment structure 1.

[0024] like Figure 1-3As shown, the battery compartment structure 1 includes a battery compartment body 11 and a plug 12. The battery compartment body 11 is provided with a battery cavity 110. Plugs 12 are provided at both ends of the battery cavity 110. The plug 12 is provided with a battery clearance hole 121, and the battery clearance hole 121 is communicated with the battery cavity 110. There is a gap between the inner wall of the battery cavity 110 and the installed battery, which serves as a accommodating cavity for thermal runaway of this section of the battery; the inner diameter of the battery clearance hole is slightly larger than the outer diameter of the installed battery, reducing the gap between the two, allowing only the battery end to pass through and enter the corresponding positive electrode injection cavity or negative electrode injection cavity, and the gas and substances generated after thermal runaway will not pass through. A data acquisition structure is provided in the battery cavity 110. The length of the battery cavity is less than the length of the battery. After the battery is assembled, the positive and negative ends of the battery are exposed to the battery cavity. The three parts of the battery are separated separately by the positive electrode injection cavity and the negative electrode injection cavity, and the three cavities are isolated from each other, and no heat transfer or communication of gas or substances occurs.

[0025] In this embodiment, the battery compartment body 11 includes two battery sub-compartments 110, which are detachably assembled together. The assembled structure is convenient for opening and removing batteries and battery residues, and a sealing structure is provided at the assembled position to seal the battery cavity. Of course, an unassembled cylindrical shape can also be used.

[0026] like Figure 2 and 3 As shown, the positive electrode injection chamber structure 2 includes a positive electrode injection tube 21, a positive electrode injection chamber 22 is arranged in the positive electrode injection tube 21, the end of the positive electrode injection chamber 22 close to the battery compartment body 11 is connected to the plug 12, and a heat insulating member 5 is arranged at the connection between the positive electrode injection chamber 22 and the plug 12, and the heat insulating member used is a heat insulating ceramic ring; the positive electrode injection chamber 22 is communicated with the battery yield hole 121; the end of the positive electrode injection chamber 22 away from the battery compartment body 11 is closed; the positive electrode injection chamber 22 is provided with an exhaust structure, and the exhaust structure uses an exhaust hole and an exhaust valve; and a jet capture structure is arranged in the positive electrode injection chamber 22. After the thermal runaway ends, the exhaust structure can discharge the gas in the positive electrode injection chamber for analyzing the components in the gas, and the jet capture structure is used to capture the heat and solid particles of the thermal runaway injection, and a data acquisition structure is arranged in the positive electrode injection chamber 22.

[0027] like Figure 2 and 3As shown, the negative electrode injection chamber structure 3 includes a negative electrode injection tube 31, a negative electrode injection chamber 32 is arranged in the negative electrode injection tube 31, and a data acquisition structure is arranged in the negative electrode injection chamber 32; the end of the negative electrode injection chamber 32 close to the battery compartment body 11 is connected to the plug 12, and a heat insulating member 5 is arranged at the connection between the negative electrode injection chamber 32 and the plug 12; the negative electrode injection chamber 32 is connected to the battery clearance hole 121; the end of the negative electrode injection chamber 32 away from the battery compartment body 11 is closed; the negative electrode injection chamber 32 is provided with an exhaust structure 7; and a spray capture structure is arranged in the negative electrode injection chamber 32. The heat insulating member used is a heat insulating ceramic ring to thermally isolate the battery cavity from the negative electrode injection chamber.

[0028] The positive electrode injection chamber structure 2 is the same as the negative electrode injection chamber structure 3. The positive electrode injection chamber, the negative electrode injection chamber and the battery chamber are connected to form a complete battery chamber. The complete battery chamber is divided into three closed chambers by the installed batteries, and there is no heat transfer between the positive electrode injection chamber, the negative electrode injection chamber and the battery chamber 110.

[0029] The jet capture structure used, such as Figure 2 and 3 As shown, it includes a central metal rod 61, a plurality of hollow baffles 62 and a grid cage 63. The central metal rod 61 is arranged along the axis direction of the battery compartment body 11. The plurality of hollow baffles 62 and the grid cage 63 are penetrated on the central metal rod 61, and the grid cage 63 is located at the end of the central metal rod 61 away from the battery compartment body 11. The central metal rod supports the hollow baffles and the grid cage on the one hand, and collects the heat of the injection on the other hand. The hollow baffle can reduce the speed of the battery injection and extinguish the fire; the hollow baffle and the grid cage together realize the collection of the injection, which is convenient for the subsequent collection and weighing of the solid matter.

[0030] In order to be able to abut against the end of the battery and facilitate the collection and measurement of the spray by the hollow baffle and the grid, the end of the central metal rod 61 close to the battery compartment body 11 is a conical end, and the end face diameter of the conical end close to the battery compartment body 11 is larger than the end face diameter of the conical end away from the battery compartment body 11.

[0031] The battery thermal runaway structure corresponds to the battery cavity 110 and triggers the installed battery to have thermal runaway. The thermal runaway structure used is a heating structure or a puncture structure. When using a heating structure, it can be directly built into the battery cavity, using a heating wire, a heating sheet, or a metal magnesium rod, etc.; an external heater can also be used to directly heat the battery compartment body; when using a puncture structure, a steel needle with an internal temperature sensor is directly used to puncture the battery, and the internal temperature change of the battery during the puncture test is measured by the internal sensor of the steel needle.

[0032] The present invention also provides a method for testing thermal runaway of a cylindrical lithium battery, comprising the following steps: Weighing the battery to be tested; the battery to be tested can be in any SOC state, and obtaining the initial battery weight; Assemble the battery to be tested into the above-mentioned device for testing thermal runaway of cylindrical lithium batteries; The shell of the battery to be tested is placed in the battery cavity 110, the positive terminal of the battery to be tested is placed in the positive electrode injection cavity 22, and the negative terminal of the battery to be tested is placed in the negative electrode injection cavity 32; during assembly, the battery cavity 110, the positive electrode injection cavity 22, and the negative electrode injection cavity 32 are independent of each other, and no heat is transferred between them, and the gas and substances generated by thermal runaway do not escape from their respective cavities; Trigger thermal runaway of the battery under test; Use a battery thermal runaway structure to trigger thermal runaway of the battery to be tested, wherein the battery thermal runaway structure is a heating structure or a needle puncture structure; and configure an X-ray tomography scanner outside the battery compartment. Use the X-ray tomography scanner to observe the changes in the entire thermal runaway process inside the battery to be tested, so as to determine the process of thermal decoupling; Analyze the thermal runaway injection conditions of the battery under test in the battery chamber 110, the positive electrode injection chamber 22, and the negative electrode injection chamber 32; For battery cavity 110: Determine the volume of gas generated by thermal runaway at the current part of the battery under test through a pressure sensor; Determine the energy generated by thermal runaway of the current part of the battery under test through a temperature sensor; Weighing the solid matter in the battery cavity 110; For the positive electrode injection chamber 22: Determine the volume of gas generated by thermal runaway at the current part of the battery under test through a pressure sensor; Determine the energy generated by thermal runaway of the current part of the battery under test through a temperature sensor; Recovering and analyzing the gas composition of the gas in the cathode injection chamber 22; Weighing the solid matter in the cathode injection chamber 22; For the cathode injection chamber 32: Determine the volume of gas generated by thermal runaway at the current part of the battery under test through a pressure sensor; Determine the energy generated by thermal runaway of the current part of the battery under test through a temperature sensor; Recovering and analyzing the gas composition of the gas in the cathode injection chamber 32; Weighing the solid matter in the cathode injection chamber 32; And weigh the battery remains.

[0033] The total energy of the jet is obtained by summing up the energy of each part, and then the proportion of the jet energy of each part in the total energy is obtained; The formula used is: Q=m iC p,i dT i ; Where i is a specific subassembly, specifically the battery chamber, cathode injection chamber or cathode injection chamber; m is the mass (g), Cp is the specific heat capacity (J / g·℃), and dT represents the temperature change (℃); According to this formula, the total energy ejected by the entire battery, the energy ejected by the positive electrode / negative electrode / shell, and the energy ratio are calculated.

[0034] By comparing the weight of solid matter in each part with the weight of battery debris, we can obtain the proportion of the material ejected from each part in the battery debris; The gas composition produced by the injection can be obtained by recovering and analyzing the gas in the positive and negative injection chambers.

[0035] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0036] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A device for testing thermal runaway of cylindrical lithium batteries, characterized in that: The invention comprises a battery compartment structure (1), a positive electrode injection chamber structure (2), a negative electrode injection chamber structure (3), a data acquisition structure and a battery thermal runaway structure, wherein the positive electrode injection chamber structure (2) and the negative electrode injection chamber structure (3) are arranged on both sides of the battery compartment structure (1), and the positive electrode injection chamber of the positive electrode injection chamber structure (2), the negative electrode injection chamber of the negative electrode injection chamber structure (3) and the battery chamber of the battery compartment structure (1) are connected to form a complete battery chamber, and the complete battery chamber is divided into three closed chambers by the installed battery, and there is no heat transfer between the positive electrode injection chamber, the negative electrode injection chamber and the battery chamber (110); the battery thermal runaway structure and the battery chamber (110) trigger the installed battery to have thermal runaway in correspondence; the positive electrode injection chamber and the negative electrode injection chamber are both provided with an exhaust structure; and the positive electrode injection chamber, the negative electrode injection chamber and the battery chamber (110) are all provided with a data acquisition structure, and the data acquisition structure comprises a pressure sensor and a temperature sensor.

2. The device for testing thermal runaway of cylindrical lithium batteries according to claim 1, characterized in that: The battery compartment structure (1) comprises a battery compartment body (11) and a plug (12); the battery compartment body (11) is provided with a battery cavity (110); plugs (12) are provided at both end openings of the battery cavity (110); the plug (12) is provided with a battery clearance hole (121); and the battery clearance hole (121) is communicated with the battery cavity (110).

3. The device for testing thermal runaway of cylindrical lithium batteries according to claim 2, characterized in that: The thermal runaway structure is a heating structure or a needle-punched structure.

4. The device for testing thermal runaway of cylindrical lithium batteries according to claim 2 or 3, characterized in that: The positive electrode injection chamber structure (2) comprises a positive electrode injection tube (21), a positive electrode injection chamber (22) is arranged in the positive electrode injection tube (21), the end of the positive electrode injection chamber (22) close to the battery compartment body (11) is connected to the plug (12), and a heat insulating member (5) is provided at the connection between the positive electrode injection chamber (22) and the plug (12); the positive electrode injection chamber (22) is communicated with the battery clearance hole (121); the end of the positive electrode injection chamber (22) away from the battery compartment body (11) is closed; the positive electrode injection chamber (22) is provided with an exhaust structure; and a spray capture structure is provided in the positive electrode injection chamber (22).

5. The device for testing thermal runaway of cylindrical lithium batteries according to claim 4, characterized in that: The negative electrode injection chamber structure (3) comprises a negative electrode injection tube (31), a negative electrode injection chamber (32) is arranged in the negative electrode injection tube (31), the end of the negative electrode injection chamber (32) close to the battery compartment body (11) is connected to the plug (12), and a heat insulating member (5) is arranged at the connection between the negative electrode injection chamber (32) and the plug (12); the negative electrode injection chamber (32) is communicated with the battery clearance hole (121); the end of the negative electrode injection chamber (32) away from the battery compartment body (11) is closed; the negative electrode injection chamber (32) is provided with an exhaust structure; and an injection capture structure is arranged in the negative electrode injection chamber (32).

6. The device for testing thermal runaway of cylindrical lithium batteries according to claim 5, characterized in that: The jet capture structure comprises a central metal rod (61), a plurality of hollow baffles (62) and a grid cage (63); the central metal rod (61) is arranged along the axial direction of the battery compartment body (11); the plurality of hollow baffles (62) and the grid cage (63) are passed through the central metal rod (61); and the grid cage (63) is located at an end of the central metal rod (61) away from the battery compartment body (11).

7. The device for testing thermal runaway of cylindrical lithium batteries according to claim 6, characterized in that: The end of the central metal rod (61) close to the battery compartment body (11) is a tapered end, and the diameter of the end surface of the tapered end close to the battery compartment body (11) is greater than the diameter of the end surface of the tapered end away from the battery compartment body (11).

8. The device for testing thermal runaway of cylindrical lithium batteries according to claim 7, characterized in that: The battery compartment body (11) comprises battery sub-compartments (110), and the battery sub-compartments (110) are detachably assembled together.

9. A method for testing thermal runaway of cylindrical lithium batteries, characterized in that: The steps are: Weigh the battery to be tested; Assembling the battery to be tested into the device for testing thermal runaway of cylindrical lithium batteries as described in any one of claims 5 to 8; The shell of the battery to be tested is placed in the battery cavity (110), the positive terminal of the battery to be tested is placed in the positive electrode injection cavity (22), and the negative terminal of the battery to be tested is placed in the negative electrode injection cavity (32); Trigger thermal runaway of the battery under test; Using a battery thermal runaway structure to trigger thermal runaway of the battery to be tested, wherein the battery thermal runaway structure is a heating structure or a puncture structure; Analyzing the thermal runaway injection conditions of the battery to be tested in the battery chamber (110), the positive electrode injection chamber (22), and the negative electrode injection chamber (32); For the battery cavity (110): Determine the volume of gas generated by thermal runaway at the current part of the battery under test through a pressure sensor; Determine the energy generated by thermal runaway of the current part of the battery under test through a temperature sensor; Weighing the solid matter in the battery cavity (110); For the cathode injection chamber (22): Determine the volume of gas generated by thermal runaway at the current part of the battery under test through a pressure sensor; Determine the energy generated by thermal runaway of the current part of the battery under test through a temperature sensor; Recovering the gas in the positive electrode injection chamber (22) and analyzing the gas composition; Weighing the solid matter in the cathode injection chamber (22); For the cathode injection chamber (32): Determine the volume of gas generated by thermal runaway at the current part of the battery under test through a pressure sensor; Determine the energy generated by thermal runaway of the current part of the battery under test through a temperature sensor; Recovering the gas in the negative electrode injection chamber (32) and analyzing the gas composition; Weighing the solid matter in the negative electrode injection chamber (32); And weigh the battery remains.

10. The method for testing thermal runaway of a cylindrical lithium battery according to claim 9, characterized in that: When triggering thermal runaway of the battery to be tested, an X-ray tomography scanner is configured outside the battery compartment.

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