Battery top cover with fire extinguishing function

Abstract

The utility model discloses a battery top cover with a fire extinguishing function, comprising a top cover which covers a battery cell space of a battery pack and seals the battery cell space; the lower plastic is connected to the side wall of one side, close to the battery cell space, of the top cover; the fire extinguishing substance is arranged between the top cover and the lower plastic; the fire extinguishing substance is at least partially exposed in the battery cell space, and when a specified index in the battery cell space is changed, the fire extinguishing substance is sprayed towards the direction of the battery cell space through the through hole and is filled in the battery cell space, so that the battery pack is wrapped in the fire extinguishing substance to isolate air in the battery cell space; through combination of the fire extinguishing device and the battery structural member, the safety accident of fire caused by thermal runaway is fundamentally solved from the battery core, and the safety performance of the battery is improved.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology, and in particular relates to a battery top cover with fire extinguishing function. Background Technology

[0002] Battery top covers with fire extinguishing capabilities are core safety protection components for power battery packs (widely used in new energy vehicles, large-scale energy storage power stations, portable energy storage devices, etc.). Their core function is to quickly activate a fire extinguishing mechanism when thermal runaway occurs due to abnormal operating conditions such as overcharging, short circuits, high temperatures, or punctures, in addition to sealing the cell space and protecting the internal cells. This suppresses the spread of fire, prevents reignition, and avoids serious safety accidents such as battery explosions and fires at the source. As power batteries develop towards higher energy density and larger sizes, the risk of thermal runaway further increases. The requirements for fire extinguishing on battery top covers have been upgraded to "rapid response, comprehensive coverage, and thorough isolation," ensuring that fire extinguishing materials can quickly fill the cell space, achieving complete cell enclosure and isolation from the air.

[0003] Existing battery top covers with fire extinguishing functions have significant structural design flaws, making it difficult to meet the core requirements of efficient fire extinguishing and safety protection for power batteries. Specific problems are as follows:

[0004] Firstly, existing fire extinguishing agents on battery top covers are mostly applied or sprayed onto the inner wall of the top cover in a single point or in a dispersed manner, without a dedicated installation and positioning structure. This results in unstable storage of the fire extinguishing agent and a limited spray / diffusion range. When a local fire occurs within the battery cell space, the fire extinguishing agent cannot quickly diffuse to the entire battery cell space, failing to achieve complete coverage of all cells. This easily leads to fire extinguishing blind spots, causing the local fire to continue to spread and eventually triggering overall thermal runaway.

[0005] Secondly, existing fire extinguishing materials mostly rely on their own decomposition and diffusion or passive heating and vaporization, lacking precise spray guidance structures. When the specified indicators such as temperature and pressure within the battery cell space reach the trigger threshold, the fire extinguishing material cannot diffuse rapidly and directionally into the battery cell space. Some of the fire extinguishing material may be carried by the high-temperature airflow to the edge of the battery cell space, failing to act on the core area of ​​the fire source in time, missing the best opportunity for early suppression of thermal runaway, resulting in a significant decrease in fire extinguishing efficiency.

[0006] Third, existing fire extinguishing structures only focus on the "fire extinguishing" aspect and lack a targeted air isolation mechanism. Even if the extinguishing material can suppress the fire temporarily, because the battery cell space is not effectively isolated from the outside air, outside air can still enter the battery cell space through gaps in the top cover, explosion-proof valves, and other channels, coming into contact with residual flammable electrolyte and decomposition gases, which can easily cause secondary fires. Furthermore, the extinguishing material cannot form a continuous isolation layer and cannot fundamentally cut off the oxygen supply required for combustion, resulting in a very high probability of reignition. Utility Model Content

[0007] The summary section of this application is intended to provide a brief overview of the concepts, which will be described in detail in the detailed description section below. This summary section is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0008] In order to overcome the problem of safety accidents caused by thermal runaway of batteries in the prior art, this utility model provides a battery top cover with fire extinguishing function.

[0009] To achieve the above objectives, this utility model adopts the following technical solution: a battery top cover with fire extinguishing function, comprising:

[0010] The top cover is placed over the cell space of the battery pack to seal the cell space.

[0011] The lower plastic part is connected to the top cover on the side closest to the battery cell space;

[0012] Fire extinguishing materials are located between the top cover and the lower plastic sheeting.

[0013] The extinguishing agent is at least partially exposed within the cell space. When a specified parameter within the cell space changes, the extinguishing agent is sprayed out through the through-hole towards the cell space and fills the cell space, thereby encasing the battery pack within the extinguishing agent to isolate the air within the cell space.

[0014] Furthermore, the lower plastic is provided with an installation groove, in which the fire extinguishing material is placed. The bottom of the installation groove is provided with multiple through holes so that the outer edge of the fire extinguishing material is exposed on the side facing the battery cell.

[0015] Furthermore, the outer edge of the extinguishing material is offset from the outer edge of the lower plastic, so that the side of the outer edge of the extinguishing material facing the battery cell is exposed.

[0016] Furthermore, the lower plastic body is provided with a groove corresponding to the explosion-proof valve of the top cover, and the bottom of the groove is provided with multiple pressure relief holes.

[0017] Furthermore, the mounting groove includes an annular portion that is positioned along the outer frame of the lower plastic.

[0018] Furthermore, the mounting groove also includes an extension that communicates with the annular portion and extends toward the groove body.

[0019] Furthermore, the installation groove is provided with multiple positioning protrusions, and the fire extinguishing material is provided with multiple positioning grooves, with the positioning protrusions inserted into the positioning grooves.

[0020] Furthermore, the battery top cover with fire extinguishing function also includes a cover plate, which is located in the mounting groove, and the fire extinguishing material is located between the mounting groove and the cover plate.

[0021] Furthermore, the bottom of the installation slot is provided with multiple support plates, which are set perpendicular to the bottom surface of the installation slot. The extinguishing material is provided with through grooves corresponding to the support plates, and the cover plate is placed on the support plates.

[0022] Furthermore, the cover plate is provided with an insert block, and the support plate is provided with a slot, into which the insert block is inserted.

[0023] The advantages of this utility model are:

[0024] A dedicated installation slot is provided on the lower plastic to hold the fire extinguishing material. Compared with the existing single-point pasting and spraying methods without positioning, it can form a stable limit for the fire extinguishing material, avoiding the problem of the fire extinguishing material falling off or shifting during battery vibration and bumps (such as when a new energy vehicle is driving), ensuring that the fire extinguishing function is always available, effectively responding to sudden thermal runaway, and solving the pain point of unstable storage of existing fire extinguishing materials.

[0025] Multiple through holes at the bottom of the installation slot form a precise spray channel. When the specified indicators such as temperature and pressure in the cell space reach the trigger threshold, the extinguishing material can be quickly and directionally sprayed into the cell space through the through holes. It does not need to rely on its own passive diffusion and can accurately act on the core area of ​​the fire source, avoiding being carried to the edge by the high-temperature airflow. It seizes the best opportunity to suppress the early stage of thermal runaway, improves the fire extinguishing response efficiency by more than 60%, and solves the defect of slow fire extinguishing response in the existing system.

[0026] Multiple through holes are evenly distributed, allowing fire extinguishing materials to be sprayed synchronously from different points, quickly filling the entire cell space and achieving full coverage of all cells without any local omissions. This completely eliminates fire extinguishing blind spots in existing fire extinguishing structures, effectively preventing overall thermal runaway caused by the spread of local fires, and meeting the core fire extinguishing requirement of "comprehensive coverage" for power batteries.

[0027] After the fire extinguishing material is wrapped around the battery cell, it forms a continuous sealed isolation layer on the surface of the battery cell and inside the battery cell space. On the one hand, it cuts off the oxygen supply required for combustion inside the battery cell space, quickly suppressing the fire; on the other hand, it effectively prevents outside air from entering the battery cell space through gaps in the top cover, explosion-proof valves and other channels, avoiding contact with residual flammable electrolyte and decomposition gases to prevent secondary ignition. This fundamentally solves the problem of incomplete air isolation and high risk of reignition in existing structures.

[0028] The fire extinguishing agent is integrated into the inside of the top cover through the lower plastic mounting groove, which is precisely matched with the sealing structure of the top cover. It will not damage the sealing performance of the cell space, effectively avoiding problems such as electrolyte leakage and external moisture infiltration. Compared with the existing layout of directly attaching to the top cover, it greatly improves the battery sealing safety and reduces the risk of battery failure.

[0029] The directional sprayed extinguishing material adheres to the surface of the battery cell and fills the battery cell space in a packaged form. It is not easy to be lost through the gaps between the battery cells and the explosion-proof valve channels, which can form a continuous and effective protection. It can cope with the high temperature and flammable materials continuously generated during thermal runaway, and avoid the problems of easy loss and short-term protection of existing extinguishing materials, thus achieving long-term protection of the battery cell.

[0030] It does not require additional complex components such as pipes, nozzles, and sensors. It achieves efficient fire extinguishing through a simple structure of "installation slot + through hole". It has low manufacturing cost and low failure risk. After the fire extinguishing material is exhausted or becomes ineffective, it can be directly removed and replaced with plastic without disassembling the entire top cover. The maintenance process is simplified and the use and maintenance cost of power battery is greatly reduced.

[0031] With a compact overall structure, it can be adapted to power battery packs in different fields such as new energy vehicles, large-scale energy storage power stations, and portable energy storage devices. It can effectively cope with thermal runaway caused by various abnormal operating conditions such as overcharging, short circuit, high temperature, and puncture, meet the safety protection needs under the trend of high energy density and large size of power batteries, and ensure the safety of power batteries throughout their entire life cycle. Attached Figure Description

[0032] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application.

[0033] Furthermore, throughout the accompanying drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the elements are not necessarily drawn to scale.

[0034] In the attached diagram:

[0035] Figure 1 This is a schematic diagram of the structure of a battery top cover with fire extinguishing function in one embodiment of the present invention.

[0036] Figure 2 for Figure 1 A cross-sectional view of the battery top cover with fire extinguishing function in the illustrated embodiment.

[0037] Figure 3 for Figure 2 Enlarged view of point A in the image.

[0038] Figure 4 for Figure 1 A schematic diagram of the lower plastic of the battery top cover with fire extinguishing function in the embodiment shown.

[0039] Figure 5 for Figure 1 A bottom view of the cover plate of the battery top cover with fire extinguishing function in the illustrated embodiment.

[0040] Figure 6 for Figure 1 An explosion diagram of the battery top cover with fire extinguishing function in the embodiment shown.

[0041] Figure 7 This is a schematic diagram showing the installation of the fire extinguishing substance and the lower plastic of the battery top cover with fire extinguishing function in another embodiment of this utility model.

[0042] Figure 8 This is a schematic diagram showing the installation of the fire extinguishing substance and the lower plastic of the battery top cover with fire extinguishing function in another embodiment of this utility model.

[0043] The meanings of the reference numerals in the figure are as follows:

[0044] 100. Top cover; 101. Protective plate; 200. Lower plastic; 201. Tank; 202. Support plate; 203. Mounting groove; 2031. Annular part; 2032. Extension part; 204. Through hole; 205. Positioning protrusion; 300. Explosion-proof valve; 400. Fire extinguishing material; 401. Positioning groove; 402. Through groove; 500. Cover plate; 501. Insert block; 600. Channel; 700. Cell space. Detailed Implementation

[0045] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0046] It should also be noted that, for ease of description, only the parts relevant to the utility model are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other.

[0047] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are used only to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0048] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0049] The names of messages or information exchanged between multiple devices in the embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of such messages or information.

[0050] This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0051] like Figure 1-6 As shown, a battery top cover with fire extinguishing function includes a top cover 100, a lower plastic 200, a fire extinguishing substance 400, an explosion-proof valve 300, and a cover plate 500.

[0052] The top cover 100 is installed on the cell space 700 of the battery pack to seal the cell space 700. The top cover 100 is equipped with positive and negative terminal structures for outputting electrical energy from the cell. The lower plastic 200 is connected to the side wall of the top cover 100 near the cell space 700. The fire extinguishing material 400 is located between the lower plastic 200 and the top cover 100. The fire extinguishing material 400 is a substance that can be made into a solid state, including perfluorohexanone and dry powder. It maintains a stable solid state at room temperature, which is convenient for storage and installation. When exposed to high temperatures, it will quickly absorb heat, decompose, and release fire extinguishing components. Among them, perfluorohexanone has high fire extinguishing performance and good environmental protection characteristics, with an ODP (ozone depletion potential) of 0 and a low GWP (global warming potential). The dry powder can enhance the fire extinguishing effect, form a physical cover, and further block oxygen.

[0053] The fire extinguishing agent 400 is at least partially exposed within the battery cell space 700. Specifically, a mounting groove 203 is provided on the lower plastic 200, and the fire extinguishing agent 400 is placed within the mounting groove 203. The bottom of the mounting groove 203 has multiple through holes 204, so that the outer edge of the fire extinguishing agent 400 facing the battery cell is exposed. When a specified parameter of the battery cell space 700 changes, the fire extinguishing agent 400 is sprayed out from the through holes 204 and fills the battery cell space 700, thereby encasing the battery pack within the fire extinguishing agent 400 to isolate the air within the battery cell space 700. By placing the fire extinguishing agent 400 directly on the lower plastic 200, a high degree of integration between the fire extinguishing device and the battery structure is achieved, without occupying the valuable battery cell space 700 inside the battery pack. This ensures the fire extinguishing function while contributing to the development of power batteries towards higher energy density.

[0054] The specified indicators include changes in air pressure, open flame, temperature, and smoke. When the air pressure inside the cell space 700 exceeds a preset threshold (such as 0.8–1.2 MPa for power batteries in new energy vehicles), the high-pressure gas can directly impact the extinguishing agent 400, causing it to be rapidly ejected through the through-hole 204. When the local temperature of the cell reaches the decomposition trigger temperature of the extinguishing agent 400 (the trigger temperature of perfluorohexanone-based solid extinguishing agents is usually 180–220°C, and the formula can be adjusted according to different battery types to adapt to their thermal runaway temperature characteristics), the extinguishing agent 400 will actively decompose and release extinguishing components, which will diffuse directionally to the high-temperature area through the through-hole 204. In addition, by integrating a smoke sensor or open flame detector inside the cell space 700, when the smoke concentration exceeds 5%obs / m or an open flame is detected, the extinguishing agent 400 spray mechanism will be triggered in conjunction with the sensor, ensuring that the extinguishing procedure can be accurately initiated at different stages of thermal runaway, capturing thermal runaway signals from all angles, and avoiding response delays or misjudgments that may occur when triggered by a single indicator.

[0055] Furthermore, the outer edge of the fire extinguishing material 400 is offset from the outer edge of the lower plastic 200, so that the side of the outer edge of the fire extinguishing material 400 facing the battery cell is exposed.

[0056] The lower plastic 200 has a groove 201 corresponding to the explosion-proof valve 300. The bottom of the groove 201 has multiple pressure relief holes, and the top cover 100 has a corresponding pressure relief groove with a protective plate 101. The explosion-proof valve 300 is installed inside the groove 201. When the pressure inside the cell space 700 abnormally rises to the opening threshold of the explosion-proof valve 300 (usually set at 1.5–2.0 MPa, slightly higher than the gas pressure trigger threshold for the extinguishing agent 400), the explosion-proof valve 300 ruptures or opens. The high-temperature, high-pressure gas inside the cell space 700 can be quickly discharged through the pressure relief holes, achieving pressure relief and preventing the battery from exploding due to excessive internal pressure. This forms a synergistic protection with the spraying of the extinguishing agent 400; first, the extinguishing agent 400 suppresses the fire, and then the explosion-proof valve 300 releases the pressure, further improving battery safety performance.

[0057] The mounting slot 203 includes an annular portion 2031 and an extension portion 2032. The annular portion 2031 is arranged along the outer frame of the lower plastic 200, and the extension portion 2032 communicates with the annular portion 2031 and extends towards the slot body 201. The density of the through holes 204 in the extension portion 2032 is greater than that in the annular portion 2031. The through holes 204 in the annular portion 2031 can uniformly spray fire extinguishing material 400 into the outer peripheral area of ​​the cell space 700, forming a preliminary enclosure barrier to prevent the fire from spreading to the edges; while the extension portion 2032, due to its higher density of through holes 204, can spray more fire extinguishing material 400 into the central area of ​​the cell space 700 and key areas prone to thermal runaway, achieving precise strike and key coverage of the fire source core, further improving the utilization efficiency and fire extinguishing accuracy of the fire extinguishing material 400.

[0058] The mounting groove 203 is provided with multiple positioning protrusions 205, and the extinguishing material 400 is provided with multiple positioning grooves 401. The positioning protrusions 205 are inserted into the positioning grooves 401. Through the interlocking of the positioning protrusions 205 and the positioning grooves 401, the circumferential and radial positions of the extinguishing material 400 in the mounting groove 203 are doubly limited, ensuring that the extinguishing material 400 is accurately aligned during installation. This avoids the impact on the spraying effect caused by the deviation between the through hole 204 and the corresponding position of the extinguishing material 400 due to installation misalignment. At the same time, it further enhances the structural stability of the extinguishing material 400 under battery vibration and impact conditions, preventing it from shaking or shifting in the mounting groove 203.

[0059] The cover plate 500 is located in the mounting groove 203, and the extinguishing agent 400 is located between the mounting groove 203 and the cover plate 500. The bottom of the mounting groove 203 is provided with multiple support plates 202, which are set perpendicular to the bottom surface of the mounting groove 203. The extinguishing agent 400 is provided with through grooves 402 corresponding to the support plates 202, and the cover plate 500 is placed on the support plates 202.

[0060] The positioning protrusion 205 not only positions the extinguishing agent 400 but also provides lateral separation, preventing overall deformation or clumping due to compression during storage and transportation, thus ensuring its structural integrity. Simultaneously, the cooperation between the through groove 402 and the support plate 202 provides additional positioning for the extinguishing agent 400, further enhancing its stability within the mounting groove 203. The cover plate 500 has an insert 501, and the support plate 202 has a slot, into which the insert 501 is inserted. The insert 501 has a conical structure, corresponding to the structure of the slot. The cooperation between the conical insert 501 and the slot guides the cover plate 500 during installation, facilitating quick and accurate alignment. Simultaneously, the cooperation ensures a stable compression of the extinguishing agent 400 by the cover plate 500, preventing premature leakage or displacement due to loosening of the cover plate 500. The cover plate 500 effectively seals and protects the fire extinguishing agent 400, preventing it from chemically reacting with electrolyte vapor and trace impurities in the cell space 700 during normal battery use and thus becoming ineffective. It also prevents the fire extinguishing agent 400 from prematurely decomposing due to long-term exposure to the normal operating temperature of the cell, ensuring that the fire extinguishing agent 400 can perform at its best when needed.

[0061] The lower plastic 200 can be connected to the top cover 100 by various methods such as adhesive, screws, or clips to install the fire extinguishing agent 400 on the top cover 100. The specific connection method can be flexibly selected according to the overall structural strength requirements of the battery top cover 100 and the assembly process requirements. For example, for power batteries with extremely high sealing requirements, a double fixing method using high-strength structural adhesive and screws can be used to ensure the sealing and stability of the connection between the lower plastic 200 and the top cover 100. For scenarios that pursue lightweighting and assembly efficiency, a clip connection can be used to achieve quick installation and disassembly, facilitating later maintenance and replacement of the fire extinguishing agent 400. Regardless of the connection method used, it is necessary to ensure that there are no gaps between the lower plastic 200 and the top cover 100 to avoid leakage of gas or electrolyte in the cell space 700, while ensuring the structural integrity of the fire extinguishing agent 400 mounting slot 203, so as not to affect the storage and spraying performance of the fire extinguishing agent 400.

[0062] like Figure 7 As shown, in another embodiment, the fire extinguishing material is at least partially offset from the lower plastic, so that a portion of the fire extinguishing material is directly above the battery pack. When changes occur in the air pressure, open flame, temperature, or smoke index within the cell space 700, the fire extinguishing material is sprayed downwards and directly enters the cell space 700, enclosing the battery pack within the fire extinguishing material 400 to isolate the air within the cell space 700.

[0063] In this embodiment, the fire extinguishing material is staggered from the lower plastic layer, allowing a portion of the fire extinguishing material to be suspended directly above the battery pack. This area is typically one of the regions where energy release is most concentrated during thermal runaway of the battery cell. If the local temperature of the battery cell rises to the decomposition trigger temperature of the fire extinguishing material, such as 200°C, the fire extinguishing material above the battery pack will preferentially decompose due to heat. The released fire extinguishing components can quickly sink under gravity, directly covering the surface of the high-temperature battery cell, rapidly extinguishing the fire or inhibiting the spread of the combustion reaction. This design further shortens the distance between the fire extinguishing material and the core of the fire, improving response speed and initial fire extinguishing efficiency.

[0064] like Figure 8 As shown, in another embodiment, a gap is left between the fire extinguishing material and the lower plastic and the side wall of the battery cell space 700, forming a channel 600 between the fire extinguishing material and the battery cell space. When changes occur in the air pressure, open flame, temperature or smoke index in the battery cell space 700, the fire extinguishing material is sprayed into the battery cell space 700 through the channel 600 reserved in the side wall of the battery cell space 700, and the battery pack is wrapped in the fire extinguishing material 400 to isolate the air in the battery cell space 700.

[0065] In embodiments where gaps exist between the extinguishing agent and the sidewall of the battery cell space 700, these gaps form an annular channel surrounding the outer perimeter of the battery cell space 700. When thermal runaway occurs in the battery cell, whether triggered by gas pressure, temperature, or sensor linkage, the extinguishing agent, after being ejected through the through-hole, will partially act directly on the central area of ​​the battery cell, while the remaining portion will enter the annular channel. The extinguishing agent entering the channel can flow downwards along the sidewall of the battery cell, gradually filling the gap between the battery cell and the casing, forming a complete protective ring from the top to the sidewall. This not only effectively prevents external oxygen from penetrating into the battery cell space 700 through the casing gaps but also provides a certain degree of cooling to the casing, preventing the high-temperature casing from igniting external combustibles or causing thermal damage to surrounding components. Simultaneously, the presence of the annular channel ensures a more uniform distribution of the extinguishing agent within the battery cell space 700, avoiding situations where the concentration of extinguishing agent is too high in some areas while other areas are insufficiently covered, thus ensuring comprehensive protection for the entire battery cell space 700. For example, in a rectangular battery pack, the width of the annular channel can be designed to be 5 to 8 mm, which ensures the flow space of the extinguishing material without taking up too much of the internal space of the battery pack, thus achieving a balance between structural compactness and fire extinguishing effect.

[0066] The above description is merely a selection of preferred embodiments of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the utility model involved in the embodiments of this disclosure is not limited to the technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in the embodiments of this disclosure.

Claims

1. A battery top cover with fire extinguishing function, characterized in that: The application relates to a battery pack fire extinguishing device. The application comprises: a top cover (100) covering a battery cell space (700) to seal the battery cell space (700); a lower plastic (200) connected to one side of the top cover (100) close to the battery cell space (700); a fire extinguishing substance (400) arranged between the top cover (100) and the lower plastic (200); 2. The battery top cover with fire extinguishing function according to claim 1, characterized in that: the fire extinguishing substance (400) is at least partially exposed in the battery cell space (700), when a specified index in the battery cell space (700) changes, the exposed part of the fire extinguishing substance (400) sprays to the battery cell space (700) and fills in the battery cell space (700), so that the battery pack is wrapped in the fire extinguishing substance (400) to isolate the air in the battery cell space (700). 3.The battery top cover with fire extinguishing function according to claim 1, characterized in that: The lower plastic (200) is provided with a mounting groove (203), the fire extinguishing substance (400) is arranged in the mounting groove (203), the bottom of the mounting groove is provided with a plurality of through holes (204), so that the side of the outer edge part of the fire extinguishing substance (400) facing the battery cell is in an exposed state.

4. The battery top cover with fire extinguishing function according to claim 2, characterized in that: The outer edge part of the fire extinguishing substance (400) and the outer edge part of the lower plastic (200) are arranged in a staggered mode, so that the side of the outer edge part of the fire extinguishing substance (400) facing the battery cell is in an exposed state.

5. The battery top cover with fire extinguishing function according to claim 4, characterized in that: The lower plastic (200) is provided with a groove body (201) corresponding to the explosion-proof valve (300) of the top cover (100), and the bottom of the groove body (201) is provided with a plurality of pressure relief holes.

6. The battery top cover with fire extinguishing function according to claim 5, characterized in that: The mounting groove (203) comprises a ring-shaped part (2031) arranged along the outer frame of the lower plastic (200).

7. The battery top cover with fire extinguishing function according to claim 2, characterized in that: The mounting groove (203) further comprises an extension part (2032) in communication with the ring-shaped part (2031), and the extension part (2032) extends to the groove body (201). 8.The battery top cover with fire extinguishing function according to claim 2, characterized in that: The mounting groove (203) is provided with a plurality of positioning convex strips (205), and the fire extinguishing substance (400) is provided with a plurality of positioning grooves (401), the positioning convex strips (205) are inserted into the positioning grooves (401). 9.The battery top cover with fire extinguishing function according to claim 8, characterized in that: The application further comprises a cover plate (500) arranged in the mounting groove (203), and the fire extinguishing substance (400) is arranged between the mounting groove (203) and the cover plate (500).

10. The battery top cover with fire extinguishing function according to claim 9, characterized in that: The bottom of the mounting groove (203) is provided with a plurality of support plates (202) arranged perpendicularly to the bottom surface of the mounting groove (203), the fire extinguishing substance (400) is provided with a through groove (402) corresponding to the support plate (202), and the cover plate (500) is arranged on the support plate (202). The cover plate (500) is provided with an insertion block (501), the support plate (202) is provided with an insertion groove, and the insertion block (501) is inserted into the insertion groove.

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