Secondary battery and battery pack

Abstract

The utility model provides a secondary battery and a battery pack, the secondary battery comprises a shell, a naked battery cell, a cover plate and a heat-resistant layer, the first end of the shell is provided with an opening; the naked battery cell is accommodated in the shell; the cover plate is connected with the first end of the shell and seals the opening, and an anti-explosion valve is arranged on the cover plate; the heat-resisting layer at least covers the side, facing the interior of the shell, of the cover plate, and the heat-resisting layer is provided with a receding area matched with the anti-explosion valve area. The heat-resistant layer is additionally arranged on the cover plate at the end of the battery shell for covering, so that the integrity of the thermal runaway lower cover plate structure is ensured, diversion of a medium under battery thermal runaway is kept to be discharged along a preset direction, disordered turbulence is prevented, thermal runaway energy is ensured to be directionally dredged, and the service life of the battery is prolonged. Heat radiation and conduction of a high-temperature medium to adjacent battery cells are effectively isolated, and the risk of thermal runaway chain reaction of the battery pack is reduced.

Description

Technical Field

[0001] This utility model relates to the field of battery structure technology, and in particular to a secondary battery and battery pack. Background Technology

[0002] Cell covers are typically installed at the ends of the cell casing and are equipped with explosion-proof valves to provide functions such as pressure relief, sealing, and fixation. During thermal runaway, the explosion-proof valve melts rapidly and ruptures in a directional manner to relieve pressure. However, the heat flow during thermal runaway can simultaneously melt the edge of the cover outside the explosion-proof valve area, causing damage to the cover edge's shape. This results in the heat flow ejected from the thermally runaway cell flowing undirected, interfering with the directional flow of heat in the heat-conducting channels within the battery pack casing outside the cell, and affecting the thermal stability of adjacent cells, thus increasing the risk of thermal runaway in the battery pack.

[0003] It should be noted that the information disclosed in the above background section is only used to enhance the understanding of the background of this utility model and does not constitute any limitation on this utility model. Utility Model Content

[0004] In view of the shortcomings of the prior art described above, this utility model provides a secondary battery and battery pack. By adding a heat-resistant layer to the cover plate at the end of the battery casing, the integrity of the cover plate structure under thermal runaway is ensured, thereby solving the problem that the heat flow generated by thermal runaway melts the edge of the cover plate, causing the heat flow to flow in an irregular direction and affecting the thermal stability of adjacent batteries.

[0005] This utility model provides a secondary battery, including a shell, a bare cell, a cover plate, and a heat-resistant layer. The first end of the shell has an opening; the bare cell is housed inside the shell; the cover plate is connected to the first end of the shell and closes the opening, and the cover plate is provided with an explosion-proof valve; the heat-resistant layer at least covers the side of the cover plate facing the inside of the shell, and the heat-resistant layer is provided with an air-proof area that matches the area of ​​the explosion-proof valve.

[0006] In one embodiment of this utility model, the heat-resistant layer also covers the area outside the cover plate except for the explosion-proof valve.

[0007] In one embodiment of the present invention, the explosion-proof valve and the cover plate are an integral structure, and the cover plate is provided with a weak part, which defines at least a portion of the outline of the explosion-proof valve.

[0008] In one embodiment of this utility model, the heat-resistant layer includes high-temperature resistant ceramics, high-temperature resistant metals, or high-temperature resistant composite materials.

[0009] In one embodiment of the present invention, the cover plate is riveted to the first end of the housing, and a sealing ring is installed between the cover plate and the housing.

[0010] In one embodiment of this utility model, the sealing ring is made of a high-temperature resistant material.

[0011] In one embodiment of this utility model, a layer of high-temperature resistant material is provided on the surface or inside of the sealing ring.

[0012] In one embodiment of this utility model, the sealing ring constitutes a heat-resistant layer.

[0013] In one embodiment of this utility model, the sealing ring covers the surface of the heat-resistant layer.

[0014] This utility model also provides a battery pack, including a secondary battery as described above and a housing, the housing containing the secondary battery, and an exhaust structure provided on the outside of the cover plate of the secondary battery.

[0015] The beneficial effects of this utility model are as follows: by adding a heat-resistant layer to the cover plate at the end of the battery casing, the integrity of the cover plate structure under thermal runaway is ensured, thereby maintaining the flow of the medium under thermal runaway along the predetermined direction, preventing disordered turbulence, ensuring the directional conduction of thermal runaway energy, effectively isolating the high-temperature medium from the thermal radiation and conduction of adjacent cells, and reducing the risk of chain reaction of thermal runaway of the battery pack.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the present invention. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments conforming to the present invention and, together with the description, serve to explain the principles of the present invention. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0018] Figure 1 This is a schematic diagram of the structure of the battery cell cover plate end in the first embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of the battery cell cover plate end in the second embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the structure of the battery cell cover plate end in the third embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the structure of the battery cell cover plate end in the fourth embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of the structure of the battery cell cover plate end in the fifth embodiment of the present invention;

[0023] Figure 6This is a schematic diagram of the battery pack structure in this utility model.

[0024] In the diagram: 10, shell; 20, cover plate; 21, weak point; 22, explosion-proof valve; 30, heat-resistant layer; 40, sealing ring; 50, interlayer; 100, box body; 200, exhaust structure. Detailed Implementation

[0025] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. It should also be understood that the terminology used in the embodiments of this utility model is for describing specific implementation schemes and not for limiting the scope of protection of this utility model.

[0026] Please see Figures 1 to 6 It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of this invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness or purpose of this invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms used in this specification regarding position, quantity, etc., are merely for clarity and not intended to limit the scope of this invention. Changes or adjustments to these relative relationships, without substantially altering the technical content, should also be considered within the scope of this invention's implementation.

[0027] Please see Figure 1 This utility model provides a secondary battery, including a housing 10, a bare battery cell, a cover plate 20, and a heat-resistant layer 30. The first end of the housing 10 is provided with an opening; the bare battery cell is housed inside the housing 10; the cover plate 20 is connected to the first end of the housing 10 and closes the opening, and an explosion-proof valve 22 is provided on the cover plate 20; the heat-resistant layer 30 at least covers the side of the cover plate 20 facing the inside of the housing 10, and the heat-resistant layer 30 is provided with an air-proof area that matches the area of ​​the explosion-proof valve 22.

[0028] Specifically, in this embodiment of the invention, the bare cells in the secondary battery are manufactured by winding or stacking processes and housed in the housing 10. The cover plate 20 is fixed to the opening of the housing 10 by an airtight connection method such as welding or riveting with a sealing ring 40 to form a sealed structure to close the opening. A pressure-responsive explosion-proof valve 22 is integrated on the cover plate 20. The opening pressure of the explosion-proof valve 22 is set to an appropriate pressure range for opening and releasing pressure in the housing 10 under thermal runaway conditions. The heat-resistant layer 30 is constructed in the form of a functionalized coating or composite layer, for example, it can be formed by a surface treatment process, covering the area of ​​the cover plate 20 facing the inside of the housing 10, especially the periphery of the explosion-proof valve 22, to completely cover the core area of ​​the inner surface of the cover plate 20 that is susceptible to high-temperature impact. A clearance zone is specifically provided that is completely matched with the pressure relief opening action area of ​​the explosion-proof valve 22, and the size of the clearance zone has an appropriate margin to ensure that the valve body of the explosion-proof valve 22 can open normally.

[0029] More specifically, the secondary battery is suitable for various packaging forms such as cylindrical and prismatic. The cover plate 20 of the cylindrical cell has a circular disc structure, while the cover plate 20 of the prismatic cell has a rectangular flat plate structure. The heat-resistant layer 30 added to the cover plate 20 can reduce the peak thermal shock temperature when the cell experiences thermal runaway and generates a high-temperature jet of air. This can be achieved through a phase change heat-absorbing material system, such as a ceramic matrix composite layer, which undergoes an endothermic phase change reaction at high temperatures. Furthermore, the heat-resistant layer 30 can construct a multi-layer heterogeneous interface, such as a gradient structure coating, utilizing the difference in thermal expansion coefficients of different materials to form a thermal buffer zone. It also includes the use of highly stable composite materials to form an effective thermal barrier. This improves the cover plate 20's resistance to transient high-temperature shocks, effectively preventing structural failure under thermal runaway conditions. Simultaneously, by optimizing the cooperation between the protective layer and the safety valve, it ensures that the pressure release device maintains reliable response performance. The structure of the heat-resistant layer 30 can be achieved through material deposition or prefabricated composite components, with its specific morphological parameters adapted to the performance requirements of different specifications of the cover plate 20.

[0030] Thus, the heat-resistant layer 30 structure can significantly improve the high-temperature resistance of the edge area of ​​the cover plate 20, effectively avoiding the melting failure of the cover plate 20 material under high-temperature conditions. At the same time, the set air-proof zone ensures that the function of the explosion-proof valve 22 is not affected, combining safety protection and pressure relief functions.

[0031] Please see Figure 2 In one embodiment, the heat-resistant layer 30 also covers the area outside the cover plate 20 except for the explosion-proof valve 22.

[0032] Specifically, in this embodiment of the invention, the casing 10, such as a steel or aluminum casing, under thermal runaway conditions, rapidly heats up due to direct contact with the high-temperature electrolyte and internal short-circuit Joule heating. Heat is conducted through the portion in contact with the cover plate 20, i.e., the area excluding the area of ​​the cover plate 20 facing inwards towards the casing 10. Therefore, a heat-resistant layer 30 is also provided on the outer side of the cover plate 20 to reduce the heat transfer efficiency of the contact area between the casing 10 and the outer side of the cover plate 20. Similarly, the high-temperature airflow guiding channel integrated within the battery pack typically has physical contact or a radiative heat transfer path with the outer side of the cover plate 20. The heat-resistant layer 30 covering the outer side of the cover plate 20 isolates it from the influence of heat radiation in the exhaust channel within the battery pack, preventing mechanical performance degradation caused by bidirectional heating (high temperature of the inner jet + heat conduction from the outer casing 10 and heat radiation from the exhaust channel within the battery pack) and preventing melting when the explosion-proof valve 22 is opened to release pressure.

[0033] In this way, by covering the area outside the cover plate 20 with the heat-resistant layer 30, not only is the interference of external heat sources on the structural stability of the cover plate 20 blocked, but the thermal management path of the battery pack is also optimized in a coordinated manner to ensure that the thermal runaway energy is dissipated in a directional manner along the preset flow channel, and finally achieves thermal safety protection for the entire battery cell and battery pack.

[0034] Please see Figures 1 to 5 In one embodiment, the explosion-proof valve 22 and the cover plate 20 are an integral structure, and the cover plate 20 is provided with a weak part 21, which defines at least a portion of the outline of the explosion-proof valve 22.

[0035] Specifically, in this embodiment of the invention, by adopting an integrated structure design for the explosion-proof valve 22 and the cover plate 20, the forming process can be optimized. By performing corresponding processing on the cover plate 20 as a whole, a weak part 21 can be formed. For example, by subtractive processing, some scratches or grooves can be formed on the cover plate 20 as the weak part 21. Alternatively, precision cutting or stamping can be used to form scratches and grooves as the weak part 21. In this way, an interface area with different mechanical properties is formed on the cover plate 20 body. Thus, under the premise of the overall structural integrity of the cover plate 20, a functional weak area with a specific fracture threshold is manufactured in a targeted manner.

[0036] Furthermore, when thermal runaway occurs in the battery cell, the weak point 21, due to its significantly reduced local thickness, preferentially undergoes controlled rupture. By matching the geometric contour of the weak point 21 with the opening area of ​​the explosion-proof valve 22 (e.g., using annular notches to define the valve body perimeter, or using a groove array to guide the rupture path), the opening direction and pressure release direction of the explosion-proof valve 22 can be precisely controlled. The high-pressure airflow generated by thermal runaway first forms stress concentration in the weak point 21, and the crack extends along the preset notch trajectory, causing the explosion-proof valve 22 to break open from the directionally designed weak area. This process achieves directional energy dissipation through a fracture path guidance mechanism—for example, the annular weak point 21 forces the crack to extend uniformly along the circumference, forming a regular circular pressure relief port; the staggered grooves guide the crack to extend in a Z-shape, extending the energy release time window. At the same time, the continuously closed contour of the weak point 21 (such as closed-loop notches) strictly limits the rupture range to the design area of ​​the explosion-proof valve 22, effectively inhibiting the spread of cracks to the edge of the cover plate 20 or the weld interface, avoiding secondary sealing failure due to structural damage. In addition, the weak part 21 can be matched with the flow guide groove provided on the inner side of the cover plate 20 to accelerate the axial discharge efficiency of the high temperature jet through fluid dynamics optimization, reduce the risk of damage to the internal structure of the battery cell by reverse thermal shock, and thus achieve a dynamic balance between pressure relief protection and structural integrity.

[0037] In one embodiment, the heat-resistant layer 30 includes high-temperature resistant ceramics, high-temperature resistant metals, or high-temperature resistant composite materials. The heat-resistant layer 30 is bonded to the cover plate 20 in the form of a coating, sheet, or film.

[0038] Specifically, in this embodiment of the invention, the heat-resistant layer 30 can be constructed using a multi-material composite method, with the material selection and molding process tailored to the specific requirements of the battery cell. For example, high-temperature resistant ceramics (such as alumina, silicon nitride, or silicon carbide-based ceramics) can be used to form a micron-level dense protective layer on the surface of the cover plate 20 through plasma spraying or vapor deposition processes, utilizing their excellent thermal stability and insulation properties to maintain structural rigidity and block heat flow erosion at high temperatures. Alternatively, high-temperature resistant metals (such as molybdenum, tungsten, or their alloys) can be used to achieve localized strengthening through laser cladding technology, utilizing the high thermal conductivity of the metal to construct a rapid heat dissipation path, which is particularly suitable for the edge areas of the cover plate 20 where both heat dissipation and heat resistance are required. A layered stacking process of high-temperature resistant composite materials (such as ceramic fiber reinforced metal matrix composites or graphene-modified polymers) can also be used, forming a gradient thermal resistance structure at the interface through the synergistic effect of heterogeneous materials, which both suppresses thermal shock transmission and improves thermal shock resistance.

[0039] Furthermore, in terms of bonding methods, the heat-resistant layer 30 can be coupled with the cover plate 20 through multi-form integration. One method involves depositing a nanocrystalline ceramic coating on the surface of the cover plate 20 using unbalanced magnetron sputtering technology. By controlling the sputtering power and gas atmosphere, the coating exhibits columnar crystal preferential orientation growth, forming a high heat flow barrier channel perpendicular to the surface of the cover plate 20. Another method involves bonding a pre-sintered ceramic or metal-based composite sheet to the cover plate 20 via laser welding or bonding. A third method involves loading nano-ceramic particles onto a flexible substrate (such as a polyimide film) and forming a composite film on the surface of the cover plate 20 through a hot-press transfer process.

[0040] Please see Figures 1 to 5 In one embodiment, the cover plate 20 is riveted to the first end of the housing 10, and a sealing ring 40 is installed between the cover plate 20 and the housing 10.

[0041] Specifically, in this embodiment of the invention, the cover plate 20 and the housing 10 are connected by riveting, and a sealing ring 40 is installed to ensure the sealing of the connection between the cover plate 20 and the housing 10. This achieves triple protection of airtightness, mechanical strength, and thermal stability through precision assembly technology. The sidewall of the first end of the housing 10 can be formed into a flange structure by roller grooving. The cover plate 20 is assembled onto the flange through its edge, and then the sidewall of the housing 10 outside the cover plate 20 is rolled to form a riveting structure. This can be achieved through a multi-station hydraulic riveting machine with progressive pressing: the first stage uses a cold riveting process to embed the edge of the cover plate 20 into the riveting groove to form a mechanical interlock; the second stage can also be performed by local induction heating to achieve micro-alloying of the interface between the cover plate 20 and the housing 10, generating a metallurgical bonding layer at the riveting interface and improving its shear resistance. During the riveting process, the sealing ring 40 is pre-compressed and installed into the sealing cavity between the cover plate 20 and the housing 10. The amount of compression is monitored in real time by the laser displacement sensor and fed back to the riveting pressure control system to ensure that the sealing stress is evenly distributed.

[0042] Thus, the riveting sealing method combined with the thermo-coupling structure achieves long-term sealing under extreme conditions. Furthermore, by matching the riveting torque gradient distribution (high torque in the central area and low torque in the edge area) between the housing 10 and the cover plate 20 with the nonlinear stiffness characteristics of the sealing ring 40, the axial displacement of the cover plate 20 during thermal runaway is absorbed by the elastic deformation of the riveting structure of the housing 10, while the circumferential expansion is offset by the waveform structure of the sealing ring 40, ensuring the sealing reliability of the battery system.

[0043] In one embodiment, the sealing ring 40 is made of a high-temperature resistant material.

[0044] Specifically, the sealing ring 40 is installed between the cover plate 20 and the housing 10, covering the surface of the cover plate 20, with its edge flush with the contour of the explosion-proof valve 22 area on the cover plate 20. Utilizing its own heat-resistant properties, the sealing ring 40 acts as a heat-resistant layer 30 on the surface of the cover plate 20. Thus, the sealing ring 40 can be made of high-temperature resistant elastomer composite materials (such as a fluororubber-ceramic fiber composite system or a silicone-graphene modified material). Reliable sealing performance under extreme conditions can be achieved through composite modification. The material system employs an organic-inorganic composite substrate and functionalized reinforcement technology. For example, a fluororubber-ceramic fiber composite system can be used to improve heat dissipation efficiency through nano-alumina fibers, while layered boron nitride is introduced as a high-temperature lubricant to reduce interfacial wear. Alternatively, a graphene-reinforced silicone system can be used, utilizing functionalized graphene sheets to construct continuous thermal conductive pathways, and hydrogen bonding between amino functional groups and silicone molecular chains can suppress high-temperature deformation. Furthermore, for ultra-high temperature regions, a polyimide-metal hybrid system can be used to achieve a balance between thermal stability and crack resistance by combining the rigid aromatic ring structure with the stress absorption capacity of the metal mesh.

[0045] Furthermore, the high-temperature adaptability of the sealing ring 40 can be improved through a gradient density distribution. For example, in a multi-layer structure, a ceramic filler layer is selected for the outer layer to resist thermal wear, a foamed silicone layer is selected for the middle layer to buffer thermal stress, and a conductive carbon fiber layer is selected for the inner layer to achieve electrostatic conduction. Surface modification technology can also be used to further enhance the performance of the sealing ring 40, laser microtexturing can store lubricating grease, plasma-grafted fluoropolymers can improve corrosion resistance, and a biomimetic hydrophobic coating can block electrolyte penetration.

[0046] Please see Figure 4 and Figure 5 In one embodiment, a high-temperature resistant material interlayer 50 is provided on the surface or inside of the sealing ring 40.

[0047] Specifically, in this embodiment of the invention, a high-temperature resistant ceramic composite layer can be deposited on the outer surface of a conventional rubber sealing ring 40 using a plasma spraying process. During the spraying process, the rubber substrate surface of the sealing ring 40 is pre-treated with laser texturing to form a micron-level anchoring structure. Subsequently, alumina-silicon carbide mixed powder is introduced, which melts and spreads on the rubber surface under the action of a high-temperature plasma beam, forming a continuous ceramic protective layer with controllable thickness. Furthermore, a gradient porosity structure can be present in its surface interlayer 50, with a dense layer close to the substrate of the sealing ring 40 to block heat flow penetration, and a porous layer on the outer surface to buffer thermal expansion stress, providing heat resistance to the sealing ring 40 structure while retaining the elastic deformation characteristics of the rubber substrate.

[0048] Furthermore, during the molding stage of the sealing ring 40, a multi-layer co-extrusion process can be used to embed high-temperature resistant materials into the rubber matrix. Specifically, a high-temperature resistant fiber woven mesh can be pre-placed in the compounded rubber as a skeleton layer. The fiber mesh is composed of silicon carbide filaments and basalt fibers interwoven in a warp and weft pattern, forming a three-dimensional reinforced structure. Subsequently, a silicone rubber composite material containing boron nitride filler is simultaneously extruded onto the upper and lower surfaces of the fiber mesh. A hot-pressing process is then used to create an interlocking interface between the functional material and the skeleton layer. This internal sandwich layer 50 system can both disperse thermal stress through the fiber network and utilize highly thermally conductive fillers to construct heat conduction paths. The ceramic-surfaced sandwich layer 50 resists direct ablation by high-temperature airflow due to its high melting point and reflects some radiant heat; the internally fiber-reinforced sandwich layer 50 bears thermal deformation loads through its three-dimensional skeleton, preventing the overall structure of the sealing ring 40 from collapsing. When subjected to instantaneous high-temperature impacts, the different sandwich layer structures 50 ensure the stability of the sealing ring 40 structure through their respective protective systems.

[0049] In this way, by forming a sandwich 50 on or inside the sealing ring 40 with a high-temperature resistant material, the ordinary sealing ring 40 is upgraded into a composite sealing component with thermal protection capabilities. Under battery thermal runaway conditions, it can effectively block the high-temperature heat flow from damaging the sealing interface and maintain the airtightness of the system.

[0050] In one embodiment, the sealing ring 40 constitutes the heat-resistant layer 30. That is, by replacing the independently disposed heat-resistant layer 30 on the surface of the cover plate 20 with the sealing ring 40 which has heat-resistant protection function, the molding steps of the cover plate 20 can be optimized, eliminating the arrangement process of the heat-resistant layer 30. On the other hand, the material layer structure of the cover plate 20 at the end of the battery casing 10 can be optimized, making it easier to arrange. It is only necessary to ensure that the sealing ring 40 fully covers the surface of the cover plate 20 except for the area of ​​the explosion-proof valve 22.

[0051] Thus, by integrating the heat-resistant protection function into the sealing ring 40 body, a structural innovation in the thermal protection of the battery cover 20 is achieved. In specific implementation, the heat-resistant sealing ring 40 directly replaces the ceramic coating or composite patch that is independently set on the surface of the traditional cover 20, forming an integrated thermal barrier-sealing composite system. In terms of assembly process, the spraying, curing, or bonding processes required for the heat-resistant layer 30 on the surface of the cover 20 are eliminated, significantly simplifying the production process of the cover 20—the complex steps such as interface treatment and thickness uniformity control between the heat-resistant layer 30 and the substrate of the cover 20 in the traditional process are completely eliminated, and the thermal protection function is integrated in one step through the installation of the standardized sealing ring 40.

[0052] More specifically, the introduction of the heat-resistant sealing ring 40 simplifies the number of material layers in the cover plate 20. In conventional solutions, a transition layer is required between the heat-resistant layer 30 on the surface of the cover plate 20 and the substrate to alleviate thermal expansion mismatch stress. However, in this embodiment, the elastic deformation capability of the sealing ring 40 material naturally absorbs the interface stress, eliminating the need for additional buffer structures. The annular contour design of the sealing ring 40 allows it to automatically cover the edge of the cover plate 20 and the outer area of ​​the explosion-proof valve 22 after installation. By simply controlling the inner diameter of the sealing ring 40 to maintain an appropriate gap with the outer edge of the explosion-proof valve 22, it is possible to ensure complete thermal protection coverage of the vulnerable part 21 of the cover plate 20, which is susceptible to high-temperature impact.

[0053] Furthermore, for the circular cover plate 20 of cylindrical batteries or the rectangular cover plate 20 of prismatic batteries, the thermal protection requirements of the entire product series can be met simply by adapting the different cross-sectional profiles of the sealing ring 40. At the same time, the replaceable feature of the sealing ring 40 facilitates the later maintenance of the battery. When the thermal protection performance degrades due to long-term use, there is no need to replace the entire cover plate 20 assembly; simply removing and installing the sealing ring 40 can restore the system's protective effectiveness.

[0054] In one embodiment, the sealing ring 40 covers the surface of the heat-resistant layer 30. That is, the heat-resistant sealing ring 40 is then placed over the heat-resistant layer 30 on the surface of the cover plate 20, forming a double-layer heat-resistant protection structure. The outer sealing ring 40 itself or the interlayer 50 disposed thereon serves as the first heat protection layer, while the inner heat-resistant layer 30 covering the cover plate 20 serves as the second heat protection layer. This ensures effective heat protection for the cover plate 20 and reduces the heat protection requirements on the heat-resistant layer 30 on the cover plate 20. Thus, by integrating this double-layer heat protection structure, improved heat protection performance is achieved within a limited space.

[0055] Please see Figure 6 The present invention also provides a battery pack, including a secondary battery as described above and a housing 100. The housing 100 houses the secondary battery and has an exhaust structure 200 on the outside of the cover plate 20 of the secondary battery.

[0056] Specifically, in this embodiment of the invention, multiple batteries are arranged in an array within the battery pack housing 100. When a single battery experiences thermal runaway, pressure is released and exhaust is achieved through the explosion-proof valve 22 on the end cover 20 of its housing 10, and the exhaust is discharged to the outside of the battery pack through the exhaust structure 200 arranged within the housing 100. During this process, the heat flow medium discharged from the thermal runaway battery must move according to the flow direction set in the exhaust structure 200 to ensure the effective discharge of the heat flow medium. The heat-resistant layer 30 structure provided on the end cover 20 of the battery housing 10 ensures that the cover 20 of the thermal runaway battery remains structurally intact when the explosion-proof valve 22 is opened for heat flow exhaust, without interfering with the discharge direction of the heat flow medium, and conforms to the flow path of the exhaust structure 200 in the battery pack housing 100, thereby maintaining the exhaust effect and preventing thermal runaway effects on adjacent batteries.

[0057] In summary, the secondary battery and battery pack provided by this utility model, by adding a heat-resistant layer to the cover plate at the battery casing end, prevents the explosion-proof valve on the cover plate from melting the edge of the cover plate during venting and depressurization under thermal runaway. Simultaneously, the heat resistance of the sealing ring is optimized to prevent seal failure and to provide additional thermal protection for the cover plate, ensuring the integrity of the cover plate structure. Furthermore, it ensures that the medium flows out in a predetermined direction under battery thermal runaway, preventing disordered turbulence, ensuring the directional conduction of thermal runaway energy, effectively isolating the high-temperature medium from thermal radiation and conduction to adjacent cells, and reducing the risk of a chain reaction of thermal runaway in the battery pack.

[0058] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A secondary battery characterized by comprising: include: A housing (10), wherein the first end of the housing (10) is provided with an opening; The bare battery cell is housed within the casing; A cover plate (20) is connected to the first end of the housing (10) and closes the opening; the cover plate (20) is provided with an explosion-proof valve (22); and A heat-resistant layer (30) covers at least one side of the cover plate (20) facing the interior of the housing (10), and the heat-resistant layer (30) is provided with an air-proof zone that matches the area of ​​the explosion-proof valve (22).

2. The secondary battery according to claim 1, characterized by The heat-resistant layer (30) also covers the area outside the cover plate (20) except for the explosion-proof valve (22).

3. The secondary battery according to claim 1, characterized by The explosion-proof valve (22) and the cover plate (20) are an integral structure. The cover plate (20) is provided with a weak part (21), which defines at least part of the outline of the explosion-proof valve (22).

4. The secondary battery according to claim 1, characterized by The heat-resistant layer (30) is made of high-temperature resistant ceramics, high-temperature resistant metals or high-temperature resistant composite materials.

5. The secondary battery according to claim 1, characterized by The cover plate (20) is riveted to the first end of the housing (10), and a sealing ring (40) is installed between the cover plate (20) and the housing (10).

6. The secondary battery according to claim 5, characterized by The sealing ring (40) is made of high-temperature resistant material.

7. The secondary battery according to claim 5, characterized by The sealing ring (40) has a high-temperature resistant material interlayer (50) on its surface or inside.

8. The secondary battery according to claim 6 or 7, characterized by The sealing ring (40) constitutes the heat-resistant layer (30).

9. The secondary battery according to claim 6 or 7, characterized by The sealing ring (40) covers the surface of the heat-resistant layer (30).

10. A battery pack, characterized in that, include: The secondary battery according to any one of claims 1 to 9; as well as The housing (100) houses the secondary battery and has an exhaust structure (200) on the outside of the cover plate (20) of the secondary battery.

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