Lithium battery multistage explosion-proof mechanism for vacuum high-temperature environment

Abstract

The invention belongs to the field of battery inactive part structures, and particularly discloses a lithium battery multistage explosion-proof mechanism used in a vacuum high-temperature environment, the lithium battery multistage explosion-proof mechanism comprises a shell, a heat absorption material and a pressure release valve, a partition plate is arranged in the shell, the partition plate divides the shell into a battery cabin and a material cabin which are relatively independent, and a plurality of pressure release holes are formed in the partition plate in a penetrating manner; the shell is provided with a pressure relief opening, and the pressure relief opening communicates with the material bin. The heat-absorbing material is granular and is filled in the material cabin; and the pressure relief valve is mounted at the pressure relief opening. Along with the heating process of the battery, the air pressure in the shell is effectively reduced through three pressure relief mechanisms, and the safety redundancy is improved.

Description

Technical Field

[0001] This invention relates to the field of non-active component structures in batteries, and in particular to a multi-level explosion-proof mechanism for lithium batteries used in vacuum high-temperature environments. Background Technology

[0002] In the field of vacuum reflow oven temperature testing instruments, existing technologies primarily address the safety risks posed by high-temperature and negative-pressure environments to built-in lithium batteries through two main approaches: First, placing the lithium battery within a sealed metal box made of aluminum alloy or stainless steel, attempting to insulate it from external high temperatures and physical impacts through the metal's high melting point and mechanical strength; second, encapsulating and curing the lithium battery entirely within a cavity using epoxy resin or ordinary silicone potting compound, aiming to protect the battery through the potting compound's fixation and a degree of heat insulation. Both existing technologies rely on the physical properties of the materials themselves to cool the battery or increase the casing strength, failing to effectively relieve the internal pressure of the lithium battery and thus failing to effectively improve safety. Summary of the Invention

[0003] The purpose of this invention is to provide a multi-level explosion-proof mechanism for lithium batteries in a vacuum high-temperature environment, so as to solve the technical problem that the existing technology does not have the ability to adjust the internal gas pressure of lithium batteries, resulting in insufficient safety.

[0004] To achieve the above objectives, embodiments of the present invention provide a multi-stage explosion-proof mechanism for lithium batteries in a vacuum high-temperature environment, comprising a housing, a heat-absorbing material, and a pressure relief valve. A partition is disposed inside the housing, dividing the housing into relatively independent battery compartments and material compartments. Multiple pressure relief holes are provided through the partition, and a pressure relief port is provided on the housing, communicating with the material compartment. The heat-absorbing material is granular and fills the material compartment. The pressure relief valve is installed at the pressure relief port.

[0005] Preferably, one side of the housing is provided with an opening, and a sealing piece is fixedly connected to the opening, the edge of the sealing piece being wavy.

[0006] Preferably, the opening is rectangular, the sealing piece is embedded in the opening, the edge of the sealing piece is fixedly connected to the inside of the opening, and at least one edge of the sealing piece is wavy.

[0007] Preferably, the opening connects the battery compartment and the material compartment, and the sealing sheet is attached to the partition and fixedly connected to the partition so that the sealing sheet covers the battery compartment and the material.

[0008] Preferably, multiple pressure relief holes are provided, and the inner diameter of the pressure relief holes is smaller than the diameter of the heat-absorbing material.

[0009] Preferably, the opening pressure of the pressure relief valve is 0.15-0.3 MPa.

[0010] Preferably, multiple pressure relief holes and pressure relief valves can be provided, with each pressure relief hole corresponding to a single pressure relief valve.

[0011] Preferably, the heat-absorbing material is a graphite phase change material with a phase change temperature of 75°C.

[0012] Preferably, the battery compartment has a silicone sealant for fixing the battery, and the silicone sealant is fixedly connected to the inner wall of the battery compartment.

[0013] Preferably, the silicone sealant has a heat resistance temperature greater than 300°C.

[0014] The multi-stage explosion-proof mechanism for lithium batteries in vacuum high-temperature environments provided by this invention has the following advantages: In the multi-stage explosion-proof mechanism for lithium batteries in vacuum high-temperature environments, if the battery heats up severely, the gas inside the casing will expand and enter the material chamber through the pressure relief hole, forming the first pressure relief mechanism; the expanded gas contacts and collides with the particulate heat-absorbing material, absorbing heat from the gas and reducing the overall gas pressure, forming the second pressure relief mechanism; when the overall gas pressure inside the casing reaches a certain limit, the gas is depressurized through the pressure relief valve, forming the third pressure relief mechanism; as the battery heats up, the three pressure relief mechanisms effectively reduce the gas pressure inside the casing, increasing the safety redundancy. Attached Figure Description

[0015] Figure 1 This is an exploded schematic diagram of a multi-level explosion-proof mechanism (without heat-absorbing materials and silicone sealant) for lithium batteries in a vacuum high-temperature environment according to an embodiment of the present invention. Figure 2 This is a cross-sectional schematic diagram of a multi-level explosion-proof mechanism for lithium batteries in a vacuum high-temperature environment (without heat-absorbing materials and silicone sealant) according to an embodiment of the present invention. In the diagram, 1 is the battery pack; 100 is the casing; 110 is the separator; 120 is the battery compartment; 130 is the material compartment; 140 is the pressure relief hole; 150 is the pressure relief port; 160 is the opening; 200 is the pressure relief valve; and 300 is the sealing plate. Detailed Implementation

[0016] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0017] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0018] In the description of this invention, "multiple" means two or more; "greater than," "less than," and "exceeding" are understood to exclude the stated number; "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0019] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0020] In actual operation, the temperature inside the vacuum reflow oven can reach 250-300℃ during the welding process. At the same time, the welding process is carried out in a vacuum environment, which is rapidly evacuated from atmospheric pressure and then restored to atmospheric pressure after welding. There are pressure differences in different areas inside the oven, and the oven temperature tester needs to work continuously in this environment. Therefore, the high temperature will cause the electrolyte to decompose and produce gas, increasing the internal pressure of the battery. The drastic pressure change may damage the battery's sealing structure. In addition, the gas inside the battery is more likely to expand in a vacuum environment, which affects the overall safety performance of the lithium battery.

[0021] To improve the safety performance of the built-in lithium battery in the vacuum reflow oven temperature tester during actual operation, refer to... Figure 1 and Figure 2 The multi-level explosion-proof mechanism for lithium batteries according to this invention includes a housing 100, a heat-absorbing material (not shown in the figure), and a pressure relief valve 200. A partition 110 is provided inside the housing 100, which divides the housing 100 into a relatively independent battery compartment 120 and a material compartment 130. The partition 110 is provided with a plurality of pressure relief holes 140. The housing 100 is provided with a pressure relief port 150, which is connected to the material compartment 130. The heat-absorbing material is in granular form and fills the material compartment 130. The pressure relief valve 200 is installed at the pressure relief port 150.

[0022] In actual installation, battery pack 1 is placed in battery compartment 120. In the multi-level explosion-proof mechanism of lithium battery, if the battery heats up severely, the gas inside the casing 100 will expand and enter the material compartment 130 through the pressure relief hole 140, forming the first pressure relief mechanism. The expanded gas comes into contact with and collides with the particulate heat-absorbing material, absorbing heat from the gas and reducing the overall gas pressure, forming the second pressure relief mechanism. When the overall gas pressure inside the entire casing 100 reaches a certain limit, the gas is depressurized through the pressure relief valve 200, forming the third pressure relief mechanism.

[0023] In summary, as the battery heats up, the separator 110 and the pressure relief hole 140 form a directional channel for gas flow, preventing high-temperature gas from directly impacting the weak parts of the casing 100. The pressure release process is guided to a preset path, and the pressure inside the casing 100 is effectively reduced through three pressure relief mechanisms, which significantly reduces the instantaneous impact intensity and increases the safety redundancy.

[0024] It is important to emphasize that the high specific surface area of ​​the granular heat-absorbing material provides a sufficient gas-solid contact interface, enabling the gas to absorb heat simultaneously during transport, thus achieving the simultaneous dissipation of pressure energy and thermal energy. Furthermore, as the gas passes through the pressure relief hole 140, the pressure relief hole 140 creates a damping effect on the gas flow, causing the pressure wave to attenuate during propagation, which can reduce the gas pressure to a certain extent.

[0025] In some embodiments, refer to Figure 1 The shell 100 has an opening 160 on one side, and a sealing piece 300 is fixedly connected to the opening 160. The edge of the sealing piece 300 is wavy.

[0026] When the pressure inside the battery compartment 120 rises abnormally, the wavy edge structure preferentially produces slight deformation at the stress concentration point. The deformation extends along the wavy lines and is transmitted to the center, making the sealing plate 300 into a curved arch structure, increasing its bending stiffness and preventing the internal battery electrolyte from spraying out.

[0027] If the pressure continues to rise beyond the design limit, the wavy edge will crack preferentially due to the higher stress amplitude than the central area, and will preferentially form radial pressure relief channels. This allows for pre-depressurization of the housing 100, which can reduce the internal pressure of the housing 100 when the sealing plate 300 is damaged, thus preventing the battery electrolyte from spraying out.

[0028] Preferably, the opening 160 is rectangular, and the sealing piece 300 is embedded in the opening 160. The edge of the sealing piece 300 is fixedly connected to the inner side of the opening 160, and at least one edge of the sealing piece 300 is wavy. The inner wall of the rectangular opening 160 is machined with stepped grooves, and the sealing piece 300 is inserted into the grooves as an insert. The wavy edge is located on the long or short side of the rectangle and is fixed to the housing 100 by laser spot welding or sealant. When the internal air pressure rises, the four sides of the rectangular sealing piece 300 are constrained differently. The wavy edge is allowed to make slight displacement due to geometric discontinuity, while the other straight edges remain rigidly constrained. The central area of ​​the entire sealing piece 300 will bulge upward to form a protruding deformation, effectively increasing the internal volume. If the pressure exceeds a threshold, the weld or adhesive layer of the wavy edge will preferentially peel off, forming a pressure relief mode with a single-sided opening, which can further relieve the pressure of the gas inside the housing 100.

[0029] Furthermore, referring to Figure 1 and Figure 2 An opening 160 connects the battery compartment 120 and the material compartment 130. A sealing plate 300 is attached to and fixedly connected to the partition 110, so that the sealing plate 300 covers the battery compartment 120 and the material compartment. A single sealing plate 300 spans two compartments, covering the surface of the partition 110, and simultaneously seals the two compartments by means of circumferential sealant or mechanical compression. When gas is generated in the battery compartment 120, the gas enters the material compartment 130 through the pressure relief hole 140 on the partition 110, and the pressure in the two compartments rises synchronously, acting together under the sealing plate 300. Under uniform pressure, the sealing plate 300 deforms as a whole. Due to its large coverage area, its relative deformation will be large, achieving pressure buffering and absorption.

[0030] In some embodiments, refer to Figure 2 Multiple pressure relief holes 140 are provided, and the inner diameter of each pressure relief hole 140 is smaller than the diameter of the heat-absorbing material. When gas is released from the battery compartment 120 to the material compartment 130, it must pass through the array of multiple pressure relief holes 140, each forming an independent jet channel. Because the hole diameter is smaller than the particle diameter, the heat-absorbing material cannot pass through the holes into the battery compartment 120. The multiple small holes disperse a large gas flow into multiple smaller gas flows. After each gas flow enters the material compartment 130, it undergoes local heat exchange with the surrounding particles, avoiding overheating in the central area and forming a temperature gradient distribution.

[0031] As a further optimization of the above embodiment, the opening pressure of the pressure relief valve 200 is 0.15-0.3 MPa. Under normal battery operation, the pressure inside the casing 100 is stable at approximately 0.1 MPa, and the pressure relief valve 200 remains sealed. When abnormal gas production from the battery causes the pressure to rise to 0.15 MPa, the pressure relief valve 200 begins to open in pressure relief mode. When the pressure reaches the 0.2-0.25 MPa range, the pressure relief valve 200 is fully open, releasing pressure from the gas inside the casing 100. When the pressure drops back to 0.1-0.12 MPa, the valve of the pressure relief valve 200 gradually closes, returning to its initial state. If the battery continues to produce gas after the first pressure relief, the above process will repeat cyclically. The opening pressure range of 0.15-0.3 MPa covers the entire pressure increase range of the lithium battery from minor abnormalities to severe thermal runaway, avoiding seal failure caused by frequent opening under normal pressure fluctuations (usually <0.05 MPa) and ensuring timely response before dangerous pressures are reached.

[0032] In some specific embodiments, multiple pressure relief ports 140 and pressure relief valves 200 may be provided, with each pressure relief port 140 corresponding to a single pressure relief valve 200. Multiple independent pressure relief valves 200 achieve modularization of the pressure relief function; the failure of a single pressure relief valve 200 will not affect the overall pressure relief protection effect, thus improving the reliability of the entire multi-stage explosion-proof mechanism for lithium batteries.

[0033] In some embodiments, the heat-absorbing material is a graphite phase change material with a phase change temperature of 75°C. The design of a phase change temperature of 75°C ensures that the heat absorption mechanism is activated immediately when the battery surface temperature exceeds the safety threshold, significantly increasing the heat absorption capacity of the material chamber 130, achieving precise control of temperature response, and enabling the multi-level explosion-proof mechanism of the lithium battery to work for a long time without failure in an environment of 250-300°C.

[0034] In some embodiments, the battery compartment 120 contains a silicone sealant (not shown) for securing the battery, which is fixedly connected to the inner wall of the battery compartment 120. Liquid silicone sealant is injected into the bottom of the battery compartment 120, and after the lithium battery is embedded, the sealant cures at room temperature or under heating conditions, forming an elastic encapsulation. The thermal expansion generated during battery pack 1 operation is absorbed by the elastic deformation of the silicone sealant, providing a cushioning effect. Secondly, the viscoelasticity of the silicone sealant allows it to encapsulate fragments, preventing short circuits and material splashing. Finally, the silicone sealant is in direct contact with the battery pack 1, also providing auxiliary heat conduction and thus reducing the heat of the battery pack 1. Preferably, the heat resistance temperature of the silicone sealant is greater than 300°C. A heat resistance temperature greater than 300°C ensures that the silicone sealant will not age and fail under normal vacuum reflow soldering conditions, ensuring a safe buffering function for broken battery pack 1 in extreme high-temperature scenarios of battery thermal runaway.

[0035] For those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of this invention, and these improvements and substitutions should also be considered within the scope of protection of this invention.

Claims

1. A multi-level explosion-proof mechanism for lithium batteries in vacuum high-temperature environments, characterized in that, include: The housing has an internal partition that divides it into a relatively independent battery compartment and a material compartment. The partition has multiple pressure relief holes that extend through it. The housing also has a pressure relief port that communicates with the material compartment. A heat-absorbing material, in granular form, is filled in the material chamber; A pressure relief valve is installed at the pressure relief port.

2. The multi-level explosion-proof mechanism for lithium batteries in vacuum high-temperature environments according to claim 1, characterized in that, The shell has an opening on one side, and a sealing piece is fixedly connected to the opening. The edge of the sealing piece is wavy.

3. The multi-level explosion-proof mechanism for lithium batteries in vacuum high-temperature environments according to claim 2, characterized in that, The opening is rectangular, the sealing piece is embedded in the opening, the edge of the sealing piece is fixedly connected to the inside of the opening, and at least one edge of the sealing piece is wavy.

4. The multi-level explosion-proof mechanism for lithium batteries in vacuum high-temperature environments according to claim 2 or 3, characterized in that, The opening connects the battery compartment and the material compartment. The sealing sheet is attached to the partition and fixedly connected to the partition so that the sealing sheet covers the battery compartment and the material compartment.

5. The multi-level explosion-proof mechanism for lithium batteries in vacuum high-temperature environments according to claim 1, characterized in that, The pressure relief holes are provided in multiple ways, and the inner diameter of each pressure relief hole is smaller than the diameter of the heat-absorbing material.

6. The multi-level explosion-proof mechanism for lithium batteries in vacuum high-temperature environments according to claim 1, characterized in that, The opening pressure of the pressure relief valve is 0.15-0.3 MPa.

7. The multi-level explosion-proof mechanism for lithium batteries in vacuum high-temperature environments according to claim 1, 5, or 6, characterized in that, Multiple pressure relief holes and pressure relief valves may be provided, with each pressure relief hole corresponding to a single pressure relief valve.

8. The multi-level explosion-proof mechanism for lithium batteries in vacuum high-temperature environments according to claim 1, characterized in that, The heat-absorbing material is a graphite phase change material with a phase change temperature of 75°C.

9. The multi-level explosion-proof mechanism for lithium batteries in vacuum high-temperature environments according to claim 1, characterized in that, The battery compartment contains silicone sealant for fixing the battery, and the silicone sealant is fixedly connected to the inner wall of the battery compartment.

10. The multi-level explosion-proof mechanism for lithium batteries in vacuum high-temperature environments according to claim 9, characterized in that, The heat resistance temperature of the silicone sealant is greater than 300℃.

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