Dual explosion-proof structure cap and battery

Abstract

The utility model relates to a double explosion -proof structure cap and battery, double explosion -proof structure cap includes cap steel sheet, polymer combination layer, cap explosion -proof aluminium spare and aluminium nickel terminal lug, the central area of cap steel sheet is equipped with the central cylinder that protrudes downward, the top or lateral wall of central cylinder is equipped with the explosion -proof hole, the one side of cap explosion -proof aluminium spare towards cap steel sheet is stamped and is formed with the pressure groove, cap explosion -proof aluminium spare is fixed in the inboard of cap steel sheet through polymer combination layer, and cap explosion -proof aluminium spare and polymer combination layer jointly block explosion -proof hole, one end of aluminium nickel terminal lug is connected to the one side of cap explosion -proof aluminium spare back to cap steel sheet, and the other end sequentially passes explosion -proof hole and central cylinder and leads to cap outside. The utility model provides a double explosion -proof structure cap and battery, has the advantages such as lower cost, process adaptability is better or reliability is higher.

Description

Technical Field

[0001] This utility model relates to the field of battery safety technology, and in particular to a double explosion-proof structure cap and its battery. Background Technology

[0002] In the field of rechargeable batteries, especially lithium-ion power batteries, safety performance has always been one of the core concerns. Under abnormal operating conditions such as overcharging, internal short circuits, or external thermal shock, the internal chemical reactions of a battery may run away from control, leading to electrolyte decomposition and the generation of a large amount of gas, causing a sudden increase in internal pressure. If the pressure is not released in time, the battery is at risk of deformation, rupture, or even more serious safety incidents.

[0003] To address this challenge, one common industry solution is to create a predetermined mechanical weak point in the battery's metal casing. A common method is to use high-precision laser processing technology to etch microgrooves of controlled depth onto the steel casing surface. When the internal pressure exceeds a design threshold, the casing will preferentially tear at this groove, thus releasing pressure. However, this approach faces several challenges in actual large-scale production. First, this solution heavily relies on ultra-high-precision laser processing equipment, which is typically expensive to acquire and requires high levels of operational stability and routine maintenance, increasing production costs. Second, the effectiveness of the laser grooving process is susceptible to various factors, such as the uniformity of the casing material thickness, overall flatness, and fluctuations in the laser's power. Even slight variations in these factors can lead to inconsistent groove depths, causing the explosion-proof opening pressure to deviate from the design window, resulting in either premature opening, delayed opening, or even failure. Furthermore, because an extremely thin residual thickness needs to be formed on the metal casing, this area becomes exceptionally fragile during subsequent battery assembly and transportation. It is prone to accidental perforation due to impacts or stress concentration, leading to battery leakage or premature failure, which poses a challenge to production yield and product consistency.

[0004] Therefore, the industry has been exploring and seeking alternative explosion-proof solutions, hoping to improve the production economy, process adaptability and quality consistency of batteries while ensuring their safety and reliability. Utility Model Content

[0005] In view of this, the present invention provides a double explosion-proof structure cap and battery, which has advantages such as low cost, good process adaptability or high reliability.

[0006] The objective of this utility model is achieved through the following technical solution: A dual explosion-proof cap includes a cap steel sheet, a polymer bonding layer, an explosion-proof aluminum part, and an aluminum-to-nickel electrode tab. The cap steel sheet has a downwardly protruding central cylinder in its central region, and an explosion-proof hole is formed on the top or side wall of the central cylinder. A groove is stamped on the side of the cap explosion-proof aluminum part facing the cap steel sheet. The cap explosion-proof aluminum part is fixed to the inner side of the cap steel sheet through the polymer bonding layer, and the cap explosion-proof aluminum part and the polymer bonding layer together seal the explosion-proof hole, forming a barrier that isolates the battery interior from the outside environment. One end of the aluminum-to-nickel electrode tab is connected to the side of the cap explosion-proof aluminum part facing away from the cap steel sheet, and the other end passes through the explosion-proof hole and the central cylinder sequentially, extending outwards from the cap.

[0007] Its primary advantage lies in the combination of the mechanical grooves on the explosion-proof aluminum cap and the material properties of the polymer bonding layer, creating a passive, externally triggered dual explosion-proof mechanism that significantly improves the battery's safety redundancy. Compared to traditional solutions relying on a single laser-etched groove, this structural design reduces reliance on high-precision laser processing equipment, resulting in lower equipment investment and maintenance costs. The explosion-proof aluminum cap is formed by stamping, a simpler and more efficient manufacturing process than laser etching, which helps improve production cycle time and overall yield. The polymer bonding layer, as an intermediate connecting medium, not only ensures reliable fixation and sealing between the cap steel sheet and the explosion-proof aluminum cap, but also forms a sealing barrier for the explosion-proof holes. Its own thermal fusion properties also provide the first layer of explosion protection. The aluminum-to-nickel tab connection and lead-out method is rationally designed to ensure reliable current output. The compact overall structure and controlled component count help achieve higher energy density within a limited space and provide the battery with two independent safety lines: one based on temperature triggering and the other on pressure triggering, thus more effectively ensuring battery safety performance under various abuse conditions.

[0008] Preferably, the trajectory of the pressure groove is a straight line, an arc, or a combination of multiple line segments, and its overall outline is located within the bottom projection range of the central cylinder of the cap steel sheet.

[0009] Defining the groove trajectory as a straight line, arc, or combination of multiple line segments provides flexibility in process design. The most suitable groove shape can be selected based on the required burst pressure threshold and aluminum material properties to optimize explosion-proof performance. More importantly, the overall contour of the groove must be within the projection range of the bottom surface of the central cylinder—a critical structural constraint. This design ensures that when the internal pressure of the battery abnormally increases, the stress acting on the explosion-proof aluminum component of the cap is effectively concentrated in the groove area, promoting its smooth opening and rupture along a predetermined path, achieving precise pressure relief. Simultaneously, this constraint also helps to strictly limit the potential rupture area to the region below the central cylinder, preventing adverse effects on the sealing area between the cap and the steel shell, further ensuring the controllability and reliability of the pressure relief process.

[0010] Preferably, the polymer bonding layer is made of modified polypropylene.

[0011] Polypropylene itself possesses excellent insulation properties and chemical stability. Modification further optimizes its specific properties, such as enhancing the bond strength with the metal cap steel sheet and explosion-proof aluminum components, ensuring the structural integrity of the cap assembly. A significant potential advantage of choosing modified polypropylene as the bonding layer material is its low heat-melting temperature. This allows it to soften or melt first when the battery experiences thermal abuse or the temperature rises to a specific range, thereby disrupting the original seal and providing an early release channel for accumulated gas and pressure inside the battery, achieving temperature-triggered active pressure relief. Furthermore, this material exhibits good processability, easily achieving uniform and reliable bonding with metal components through hot pressing and other methods, which is beneficial for the stability and consistency of large-scale production.

[0012] Preferably, the side wall of the central cylinder has a hole, which constitutes or partially constitutes the explosion-proof hole.

[0013] This design offers a direct spatial advantage: it effectively frees up space on the top face of the central cylinder. This allows the outer surface of the cap steel sheet to provide a larger, more continuous, and flatter annular welding area during subsequent battery pack integration or end-application welding, greatly facilitating wire welding and improving the reliability and efficiency of the welded connection. Simultaneously, placing the explosion-proof hole on the sidewall does not affect its basic function; the aluminum-to-nickel tab can still pass through smoothly, and the polymer bonding layer and the explosion-proof aluminum cap can still effectively seal the hole. Therefore, this design provides additional practical assembly convenience while fully retaining the original explosion-proof function.

[0014] Preferably, it also includes an insulating pad, which is attached to the outside of the cap steel sheet and covers the top of the central cylinder.

[0015] Because the aluminum-to-nickel tabs extend from the central cylinder, and the surrounding cap steel sheet is typically connected to the other polarity of the battery, there is a risk of short circuit between them. The insulating pad, attached to the outside of the cap steel sheet and covering the top of the central cylinder, physically isolates the extended aluminum-to-nickel tabs from the surface of the cap steel sheet, effectively preventing accidental electrical short circuits caused by foreign objects or improper installation, thus enhancing the inherent safety and reliability of the battery. Furthermore, this insulating pad also provides some dust and contamination protection for the explosion-proof opening at the top of the central cylinder or the tab lead-out point, providing additional protection for sensitive electrical connections and helping to maintain the long-term stability of the battery operation.

[0016] Preferably, it also includes a cured adhesive layer, which fills the internal cavity of the explosion-proof hole and / or the central cylinder.

[0017] Its advantages are mainly reflected in mechanical fixation and enhanced reliability. When the aluminum-to-nickel tabs pass through the explosion-proof hole and the central cylindrical cavity, there may be some room for movement. The filling and curing adhesive layer can firmly bond and fix the position of the tabs, making them difficult to shift or loosen due to transportation vibration, accidental pulling, or internal pressure impact. This helps maintain the stability of the electrical connection path, avoiding problems such as internal or external short circuits or increased connection resistance caused by tab movement. At the same time, this adhesive layer can supplement the sealing of the tiny gaps between the tabs and the metal hole walls, further enhancing the overall sealing performance of the cap and providing a certain degree of stress buffering and protection for the tabs themselves.

[0018] Preferably, the cured adhesive layer is a UV-curable adhesive.

[0019] Choosing this type of adhesive offers advantages in the production process. UV-curing adhesives typically cure rapidly within seconds under specific wavelengths of ultraviolet light, significantly reducing waiting time in the production process and improving assembly line cycle time and efficiency. The rapid curing characteristic also means that tabs can be fixed in place more quickly, reducing the risk of positional deviations caused by movement before curing. Furthermore, the UV curing process is usually carried out at room temperature, without the need for heating. This avoids adverse thermal effects from high temperatures on surrounding polymer bonding layers, insulating materials, or other internal battery components, contributing to the stability and consistency of the overall product performance.

[0020] Preferably, the section of the aluminum-to-nickel electrode tab that passes through the explosion-proof hole is covered with the cured adhesive layer to insulate the aluminum-to-nickel electrode tab from the cap steel sheet.

[0021] The core advantage of this design lies in providing another direct and reliable insulation barrier. Although a polymer bonding layer covers the inside of the explosion-proof hole, the metal tab directly penetrates the metal cap steel sheet (explosion-proof hole), posing a potential short-circuit risk. Pre-coating this area where the tab passes through the explosion-proof hole ensures complete insulation between the aluminum-to-nickel tab and the cap steel sheet, significantly enhancing electrical safety. This design provides double protection: an external insulating pad prevents short circuits from external contact, and an internal insulating coating prevents short circuits from contact with the hole wall, comprehensively improving the insulation level and short-circuit withstand capability of the cap module.

[0022] A battery includes a steel casing and a battery cell, wherein the opening of the steel casing is sealed with a double explosion-proof cap as described above.

[0023] Its primary advantage lies in integrating all the potential benefits of the cap, thus exhibiting superior safety performance. Under abnormal conditions such as overcharging, short circuits, and thermal abuse, the battery is prone to gas generation and a sudden pressure surge. The cap's dual explosion-proof mechanism (polymer layer thermal fusion and aluminum component groove rupture) provides two levels of pressure relief protection, effectively reducing the risk of battery explosion. Secondly, because this cap structure simplifies production and improves yield, it ultimately helps reduce the overall manufacturing cost of the battery. Furthermore, the opening design on the side wall of the cap's central post facilitates battery terminal connection. Therefore, this battery not only enhances safety but also offers corresponding advantages in terms of production economy and operational reliability.

[0024] Preferably, the outer surface of the cap steel sheet, excluding the area occupied by the central cylinder, forms a smooth annular welding area.

[0025] This structural feature offers significant practical advantages for subsequent battery integration applications. The flat and wide annular welding area provides an ideal interface for laser welding or ultrasonic welding during battery module (PACK) processes, facilitating a stronger and more reliable electrical connection between wires or connectors and battery terminals. Good weld quality reduces connection resistance, minimizes heat generation, and improves the overall energy efficiency and operational stability of the battery module. Simultaneously, this design allows for easier automation of welding operations, increasing production efficiency and reducing process defects such as incomplete or uneven welds, leading to poor welds and ultimately enhancing the overall quality and consistency of the final battery product.

[0026] The advantages of this utility model compared to the prior art are: The battery cap structure proposed in this utility model exhibits many beneficial effects compared with existing technical solutions.

[0027] The core of this solution lies in providing a dual explosion-proof mechanism based on structural innovation. The first layer of protection relies on the thermal response characteristics of a specific polymer material layer. When the internal temperature of the battery rises to the temperature range of this material due to abnormal conditions, this bonding layer softens, melts, or loses its adhesiveness, thus breaking the seal first and creating a venting channel, achieving temperature-triggered active pressure relief. The second layer of protection is achieved through a metal sheet with precise indentations. These indentations, formed by a stamping process, constitute a mechanical weak point. If internal pressure continues to accumulate and reaches a critical value, the metal sheet will preferentially deform and rupture at the indentation under pressure, providing a direct pressure release path. This dual-triggered design of temperature and pressure constitutes redundant safety protection, giving the battery a higher safety margin and reliability when facing different abuse conditions.

[0028] In terms of manufacturing, this solution demonstrates excellent process friendliness. The key feature used to define burst pressure—the indentation on the metal sheet—is formed in a single step through a stamping process, which is characterized by high efficiency and fast turnaround time. Compared to laser grooving, stamping is less sensitive to microscopic inhomogeneities in the material and avoids the investment in expensive and high-maintenance laser equipment, thus enabling the reduction of manufacturing costs and equipment maintenance complexity. Furthermore, the residual thickness of the indentation formed by stamping is relatively more controllable, which helps reduce the risk of mechanical damage in subsequent processes, positively impacting production yield and product consistency.

[0029] Furthermore, the cap structure is designed with battery integration in mind. The vent is positioned on the centrally protruding sidewall, creating a wide and flat annular area around its top perimeter. This area provides ample and ideal working surface for welding connectors during battery module assembly, improving the ease of welding operations and the reliability of connection points.

[0030] In summary, this utility model, through its unique structural design, provides a beneficial battery explosion-proof solution in terms of achieving dual safety protection in one integrated manner, optimizing manufacturing processes, potentially reducing costs, and enhancing integration convenience. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1This is an exploded view of the battery explosion-proof cap of Embodiment 1 of this utility model.

[0033] Figure 2 This is a cross-sectional view of the battery explosion-proof cap of Embodiment 1 of this utility model.

[0034] Figure 3 for Figure 2 A magnified view of region A in the middle.

[0035] Figure 4 This is an exploded view of the battery in Embodiment 2 of this utility model.

[0036] Figure 5 This is a cross-sectional view of the battery in Embodiment 2 of this utility model.

[0037] Figure 6 for Figure 5 A magnified view of region B in the middle.

[0038] Labeling Explanation: 1. Cap steel sheet, 11. Central cylinder, 12. Explosion-proof hole, 2. Polymer bonding layer, 3. Cap explosion-proof aluminum part, 31. Pressure groove, 4. Aluminum to nickel electrode tab, 5. Insulating pad, 6. Curing adhesive layer, 7. Steel shell, 8. Battery cell. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0041] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of the embodiments of this application, it should be understood that the terms "upper," "lower," "left," "right," "vertical," "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figures, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only for the convenience of describing this application 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 limitations on this application.

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0043] The technical solutions in this application will now be described with reference to the accompanying drawings. Example 1

[0044] This embodiment provides a dual explosion-proof structure cap, including a cap steel sheet 1, a polymer bonding layer 2, a cap explosion-proof aluminum part 3, and an aluminum-to-nickel tab 4; the cap steel sheet 1 has a downwardly protruding central cylinder 11 in its central area, and an explosion-proof hole 12 is opened on the top or side wall of the central cylinder 11; the cap explosion-proof aluminum part 3 has a groove 31 stamped on the side facing the cap steel sheet 1; the cap explosion-proof aluminum part 3 is fixed to the inner side of the cap steel sheet 1 by the polymer bonding layer 2, and together with the polymer bonding layer 2, seals the explosion-proof hole 12, forming a barrier that isolates the inside of the battery from the outside; one end of the aluminum-to-nickel tab 4 is connected to the side of the cap explosion-proof aluminum part 3 facing away from the cap steel sheet 1, and the other end passes through the explosion-proof hole 12 and the central cylinder 11 in sequence and is led out to the outside of the cap.

[0045] Its primary advantage lies in the combination of the mechanical groove 31 on the explosion-proof aluminum cap 3 and the material properties of the polymer bonding layer 2, which constructs a passive, externally triggered dual explosion-proof mechanism, significantly improving the battery's safety redundancy. Compared to the traditional solution relying on a single laser grooving, this structural design reduces reliance on high-precision laser processing equipment, resulting in lower equipment investment and maintenance costs. The groove 31 on the explosion-proof aluminum cap 3 is formed by stamping, a simpler and more efficient manufacturing process than laser grooving, which helps improve production cycle time and overall yield. The polymer bonding layer 2, as an intermediate connecting medium, not only achieves reliable fixation and sealing between the cap steel sheet 1 and the explosion-proof aluminum cap 3, but also forms a sealing barrier for the explosion-proof hole 12 together with it. Its own heat-melting properties also provide the possibility for the first layer of explosion protection. The connection and lead-out method of the aluminum-to-nickel tab 4 is reasonably designed to ensure reliable current output. The compact overall structure and controlled number of components help achieve higher energy density in a limited space and provide the battery with two independent safety lines, one based on temperature triggering and the other based on pressure triggering, thus more effectively ensuring the battery's safety performance under different abuse conditions.

[0046] In this embodiment, the trajectory of the pressure groove 31 is a straight line, an arc, or a combination of multiple line segments, and its overall outline is located within the bottom projection range of the central cylinder 11 of the cap steel sheet 1.

[0047] By defining the trajectory of the pressure groove 31 as a straight line, arc, or a combination of multiple line segments, flexibility in process design is provided. The most suitable shape of the pressure groove 31 can be selected based on the actual required burst pressure threshold and aluminum material properties to optimize explosion-proof performance. More importantly, the overall outline of the pressure groove 31 must be within the projection range of the bottom surface of the central cylinder 11, which is a key structural constraint. This design ensures that when the internal pressure of the battery abnormally increases, the stress acting on the explosion-proof aluminum part 3 of the cap can be effectively concentrated in the pressure groove 31 area, thereby promoting its smooth opening and rupture along a predetermined path and achieving precise pressure relief. At the same time, this constraint also helps to strictly limit the possible rupture range to the area below the central cylinder 11, avoiding adverse effects of rupture behavior on the sealing area of ​​the cap periphery and the steel shell 7, further ensuring the controllability and reliability of the pressure relief process.

[0048] In this embodiment, the polymer bonding layer 2 is made of modified polypropylene, which is modified to improve the bonding strength.

[0049] Polypropylene itself possesses excellent insulation properties and chemical stability. Modification further optimizes its specific properties, such as enhancing the bond strength between the polypropylene and the metal cap steel sheet 1 and the explosion-proof aluminum component 3, ensuring the structural integrity of the cap assembly. A significant potential advantage of choosing modified polypropylene as the bonding layer material is its low heat-melting temperature. This allows it to soften or melt first when the battery experiences thermal abuse or the temperature rises to a specific range, thereby disrupting the original seal and providing an early release channel for accumulated gas and pressure inside the battery, achieving temperature-triggered active pressure relief. Furthermore, this material exhibits good processability, easily achieving uniform and reliable bonding with metal components through hot pressing and other methods, which is beneficial for the stability and consistency of large-scale production.

[0050] In this embodiment, a hole is provided on the side wall of the central cylinder 11, which constitutes or partially constitutes the explosion-proof hole 12.

[0051] This design offers a direct spatial advantage: it effectively frees up space on the top surface of the central cylinder 11. This allows the outer surface of the cap steel sheet 1 to provide a larger, more continuous, and flatter annular welding area during subsequent battery pack integration or end-application welding, greatly facilitating wire welding and improving the reliability and efficiency of the welded connection. Simultaneously, placing the explosion-proof hole 12 on the sidewall does not affect its basic function; the aluminum-to-nickel tab 4 can still pass through smoothly, and the polymer bonding layer 2 and the explosion-proof aluminum cap 3 can still effectively seal the hole. Therefore, this design provides additional practical assembly convenience while fully retaining the original explosion-proof function.

[0052] In this embodiment, an insulating pad 5 is also included. The insulating pad 5 is attached to the outside of the cap steel sheet 1 and covers the top of the central cylinder 11.

[0053] Since the aluminum-to-nickel tab 4 extends from the central cylinder 11, and the surrounding cap steel sheet 1 is typically connected to the other polarity of the battery, there is a risk of short circuit between them. The insulating pad 5, attached to the outside of the cap steel sheet 1 and covering the top of the central cylinder 11, physically isolates the extended aluminum-to-nickel tab 4 from the surface of the cap steel sheet 1, effectively preventing accidental electrical short circuits caused by foreign objects or improper installation, thus enhancing the inherent safety and reliability of the battery. Furthermore, this insulating pad 5 also provides some dust and contamination protection for the explosion-proof hole 12 opening at the top of the central cylinder 11 or the tab lead-out point, providing additional protection for sensitive electrical connection points and helping to maintain the long-term stability of the battery operation.

[0054] In this embodiment, a curing adhesive layer 6 is also included. The curing adhesive layer 6 fills the internal cavity of the explosion-proof hole 12 and / or the central cylinder 11 to fix the position of the aluminum to nickel electrode tab 4 and enhance the seal.

[0055] Its advantages are mainly reflected in mechanical fixation and enhanced reliability. The aluminum-to-nickel tab 4 may have some room for movement when passing through the explosion-proof hole 12 and the cavity of the central cylinder 11. The filling and curing adhesive layer 6 can firmly bond and fix the position of the tab, making it difficult for it to shift or loosen due to transportation vibration, accidental pulling, or internal pressure impact. This helps maintain the stability of the electrical connection path and avoids problems such as internal and external short circuits or increased connection resistance caused by tab shaking. At the same time, this adhesive layer provides a supplementary seal for the small gaps between the tab and the metal hole wall, further enhancing the overall sealing performance of the cap and providing a certain degree of stress buffering and protection for the tab itself.

[0056] In this embodiment, the cured adhesive layer 6 is a UV-curable adhesive.

[0057] Choosing this type of adhesive offers advantages in the production process. UV-curing adhesives typically cure rapidly within seconds under specific wavelengths of ultraviolet light, significantly reducing waiting time during production and improving assembly line cycle time and efficiency. The rapid curing characteristic also means that tabs can be fixed in place more quickly, reducing the risk of positional deviations due to movement before curing. Furthermore, the UV curing process is usually carried out at room temperature, without heating, avoiding adverse thermal effects on the surrounding polymer bonding layer, insulating materials, or other internal battery components, thus ensuring the stability and consistency of the overall product performance.

[0058] In this embodiment, the middle section of the aluminum-to-nickel electrode tab 4 is covered with a curing adhesive layer 6. The curing adhesive layer 6 is disposed at the part of the aluminum-to-nickel electrode tab 4 that passes through the explosion-proof hole 12, and is used to fix the position of the electrode tab and provide insulation.

[0059] The core advantage of this design lies in providing another direct and reliable insulation barrier. Although the polymer bonding layer 2 covers the inside of the explosion-proof hole 12, the metal tab directly passes through the metal cap steel sheet 1 (explosion-proof hole 12), posing a potential short-circuit risk. Pre-coating the area where the tab passes through the explosion-proof hole 12 with an insulating layer ensures complete insulation between the aluminum-to-nickel tab 4 and the cap steel sheet 1, significantly enhancing electrical safety. This design constitutes double protection: an external insulating pad 5 prevents short circuits from external contact, and an internal insulating coating layer prevents short circuits from contact with the hole wall, comprehensively improving the insulation level and short-circuit withstand capability of the cap module. Example 2

[0060] A battery includes a steel casing 7 and a battery cell 8, wherein the opening of the steel casing 7 is sealed with a double explosion-proof cap as in Example 1.

[0061] Its primary advantage lies in integrating all the potential benefits of the cap, thus exhibiting superior safety performance. Under abnormal conditions such as overcharging, short circuits, and thermal abuse, the battery is prone to gas generation and a sudden pressure surge. In such situations, the cap's dual explosion-proof mechanism (polymer layer 2 hot-melt and aluminum component 3 pressure groove 31 rupture) provides two levels of pressure relief protection, effectively reducing the risk of battery explosion. Secondly, because this cap structure simplifies production and improves yield, it ultimately helps reduce the overall manufacturing cost of the battery. Furthermore, the opening design on the side wall of the cap's central post 11 facilitates battery terminal connection. Therefore, this battery not only enhances safety but also offers corresponding advantages in terms of production economy and operational reliability.

[0062] In this embodiment, the outer surface of the cap steel sheet 1, excluding the area occupied by the central cylinder 11, forms a ring-shaped flat welding area.

[0063] This structural feature offers significant practical advantages for subsequent battery integration applications. The flat and wide annular welding area provides an ideal interface for laser welding or ultrasonic welding during battery module (PACK) processes, facilitating a stronger and more reliable electrical connection between wires or connectors and battery terminals. Good weld quality reduces connection resistance, minimizes heat generation, and improves the overall energy efficiency and operational stability of the battery module. Simultaneously, this design makes welding operations easier to automate, increases production efficiency, and reduces process defects such as incomplete or uneven welds, leading to poor welds and ultimately enhancing the overall quality and consistency of the final battery product.

[0064] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A double explosion-proof cap, characterized in that, include: The cap steel sheet (1), polymer bonding layer (2), cap explosion-proof aluminum part (3) and aluminum to nickel electrode tab (4); The cap steel sheet (1) has a downward protruding central cylinder (11) in the central area, and the top or side wall of the central cylinder (11) has an explosion-proof hole (12). The explosion-proof aluminum cap (3) has a groove (31) stamped on the side facing the steel cap (1). The explosion-proof aluminum cap (3) is fixed to the inner side of the steel cap (1) through the polymer bonding layer (2), and the explosion-proof aluminum cap (3) and the polymer bonding layer (2) together seal the explosion-proof hole (12). One end of the aluminum-to-nickel electrode tab (4) is connected to the side of the explosion-proof aluminum part (3) facing away from the cap steel sheet (1), and the other end passes through the explosion-proof hole (12) and the central cylinder (11) in sequence and extends outward to the outside of the cap.

2. The double explosion-proof structure cap according to claim 1, characterized in that, The trajectory of the groove (31) is a straight line, an arc or a combination of multiple line segments, and its overall outline is located within the bottom projection range of the central cylinder (11) of the cap steel sheet (1).

3. The double explosion-proof cap according to claim 1, characterized in that, The polymer bonding layer (2) is made of modified polypropylene.

4. The double explosion-proof structure cap according to claim 1, characterized in that, The side wall of the central cylinder (11) has a hole, which constitutes or partially constitutes the explosion-proof hole (12).

5. A double explosion-proof cap according to claim 1, characterized in that, It also includes an insulating pad (5) which is attached to the outside of the cap steel sheet (1) and covers the top of the central cylinder (11).

6. A double explosion-proof cap according to claim 1, characterized in that, It also includes a cured adhesive layer (6) that fills the internal cavity of the explosion-proof hole (12) and / or the central cylinder (11).

7. A double explosion-proof structure cap according to claim 6, characterized in that, The cured adhesive layer (6) is a UV-curable adhesive.

8. A double explosion-proof structure cap according to claim 6, characterized in that, The section of the aluminum-to-nickel tab (4) passing through the explosion-proof hole (12) is covered with the cured adhesive layer (6) to insulate the aluminum-to-nickel tab (4) from the cap steel sheet (1).

9. A battery comprising a steel casing (7) and a battery cell (8), characterized in that, The opening of the steel shell (7) is sealed with a double explosion-proof structure cap as described in any one of claims 1-8.

10. A battery according to claim 9, characterized in that, The outer surface of the cap steel sheet (1), excluding the area occupied by the central cylinder (11), forms a ring-shaped flat welding area.

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