Battery cover plate, preparation method of battery cover plate and secondary battery

Abstract

The invention provides a battery cover plate, a preparation method of the battery cover plate and a secondary battery, the battery cover plate comprises a body, the body is provided with pre-adjusting holes, and the pre-adjusting holes penetrate through the body along the thickness direction of the body; the pre-exhaust assembly comprises a stop layer and a connecting layer which are connected with each other, the connecting layer is connected with the stop layer and the body in an attached mode, and the stop layer covers the pre-adjusting hole. The pre-adjusting hole and the pre-exhausting assembly are arranged on the body, so that the function of automatically and spontaneously communicating the internal environment and the external environment of the battery when the temperature and the pressure inside the battery are increased and increased is realized. When the internal temperature of the battery rises and the pressure is increased, the pre-exhaust assembly can respond quickly and open the communication channel in time, and the design fundamentally solves the problem of battery thermal runaway explosion possibly caused by poor consistency of the explosion-proof holes in the prior art. Compared with a conventional battery cover plate structure at the present stage, the battery cover plate structure disclosed by the invention has higher use safety and self-adaptive adjustability.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery cover plate, a preparation method of the battery cover plate and a secondary battery. Background Art

[0002] As the global demand for clean energy continues to grow, the new energy sector is developing rapidly, especially in applications such as electric vehicles and energy storage systems. As core components, batteries have attracted much attention for their performance and safety. Batteries with high energy density can provide equipment with longer operating time and stronger power support. Therefore, improving battery energy density has become one of the key goals of industry development. However, as energy density increases, the heat generated by the battery during operation also increases accordingly, which greatly increases the risk of thermal runaway of the battery. Once thermal runaway occurs, it may cause fire or even explosion, posing a serious threat to the safety of people and property.

[0003] In order to ensure the safe operation of the battery, the batteries currently on the market are usually equipped with a safety valve design. The function of the safety valve is to open when the internal pressure of the battery is too high to release pressure and exhaust gas to prevent the battery from rupturing or exploding due to excessive pressure. However, there are many defects in the existing safety valve. On the one hand, the safety valve will only open for pressure relief and exhaust when a certain pressure is reached, which leads to a long time period from the occurrence of thermal runaway to the opening of the safety valve. During this period, the heat and pressure inside the battery continue to accumulate, greatly increasing the level of danger. On the other hand, the opening of the safety valve is greatly affected by its own factors. For example, during the battery assembly welding process, the welding process and operation may cause a certain degree of damage to the safety valve, which in turn leads to poor consistency in the opening pressure of the safety valve. This inconsistency may cause the safety valve of some batteries to open only under excessively high pressure, or to open by mistake under normal operating pressure, which seriously affects the safety and stability of the battery. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the problem of low consistency of battery safety valves in the prior art, and to provide a battery cover, a method for preparing the battery cover, and a secondary battery.

[0005] In order to solve the above technical problems, the present invention provides a battery cover, which includes: a main body, wherein the main body is provided with an explosion-proof hole and a pre-adjustment hole, and the explosion-proof hole and the pre-adjustment hole both penetrate the main body along the thickness direction of the main body, wherein an explosion-proof plate is provided in the explosion-proof hole; a pre-exhaust component, wherein the pre-exhaust component is arranged corresponding to the pre-adjustment hole, and comprises a stop layer and a connecting layer connected to each other, wherein one side of the connecting layer is adhered to the main body, and the other side is connected to the stop layer, and the stop layer covers the pre-adjustment hole; the connecting layer melts when it reaches a preset melting point, so that the stop layer is separated from the main body and the pre-adjustment hole is exposed.

[0006] In one embodiment of the present invention, the pre-exhaust component further includes an insulating layer, and the insulating layer and the connecting layer are respectively located on two opposite sides of the stopping layer in the thickness direction.

[0007] In one embodiment of the present invention, the preset melting point is 90-140° C., the connecting layer substrate is a polymer hot-melt material, and the stopping layer substrate is a metal.

[0008] In one embodiment of the present invention, the battery cover further includes a connection assembly, the connection assembly includes a pressing block and a rivet, the pressing block is arranged on the main body, and the rivet is penetrated to connect the pressing block and the main body.

[0009] In one embodiment of the present invention, the connection assembly includes an upper plastic, a lower plastic and a sealing ring, the upper plastic and the lower plastic are respectively arranged on both sides of the body in the thickness direction, and the upper plastic is arranged between the body and the pressure block, the rivet is sequentially penetrated and connected to the lower plastic, the body, the upper plastic and the pressure block, and the rivet and the lower plastic are abutted against each other, and a sealed expansion space is jointly enclosed by the rivet, the upper plastic, the body and the lower plastic, and the sealing ring is arranged around the rivet and is located in the sealed expansion space.

[0010] In one embodiment of the present invention, the rivet comprises an inserting portion, a welding portion and a limiting portion, wherein the inserting portion is arranged to connect the pressure block, the upper plastic and the main body, the welding portion is arranged at one end of the inserting portion away from the pressure block, and extends perpendicularly to the inserting portion, the limiting portion is connected to the extended end of the welding portion, and the thickness of the limiting portion is less than the thickness of the welding portion, so as to form a step surface at the connection between the limiting portion and the welding portion, and the lower plastic abuts against the step surface.

[0011] In one embodiment of the present invention, the main body is provided with an expansion-shaped protrusion, and the upper plastic is provided with an accommodating groove corresponding to the expansion-shaped protrusion, and the expansion-shaped protrusion can be embedded in the accommodating groove.

[0012] The present invention also provides a method for preparing a battery cover, which is used to process and prepare the above-mentioned battery cover, and includes: step S1, adhering and connecting the pre-formed stop layer and the connecting layer to obtain a pre-exhaust component; step S2, placing the pre-exhaust component at the pre-adjustment hole of the main body, and adhering and connecting the connecting layer to the main body; step S3, heating and pressurizing the pre-exhaust component, maintaining it for a first preset time and then stopping; step S4, high-frequency pressing the pre-exhaust component to make the main body and the stop layer self-heat, maintaining it for a second preset time and then stopping; step S5, leaving the main body and the pre-exhaust component still until they are cooled to obtain the target battery cover.

[0013] In one embodiment of the present invention, in step S1, the insulating layer, the stopping layer and the connecting layer are pre-formed respectively, and then the insulating layer and the connecting layer are connected on opposite sides in the thickness direction of the stopping layer respectively to obtain a pre-exhaust component; at the same time, the main body is stamped to prepare a pre-adjustment hole.

[0014] In one embodiment of the present invention, in step S2, before placing the pre-exhaust assembly at the pre-adjustment hole of the body, the surface of the body is sequentially subjected to oil cleaning, nano-corrosion processing and passivation treatment.

[0015] In one embodiment of the present invention, in step S3, the temperature at which the pre-exhaust component is heated is 190-230° C., and the first preset time is 5-20 s; in step S4, the second preset time is 0.1-1.0 s.

[0016] The present invention also provides a secondary battery, which includes the battery cover, a shell and an electrode group. The electrode group and the electrolyte are arranged inside the shell, and the cover is connected to the shell opening to seal the internal environment of the shell.

[0017] The above technical solution of the present invention has the following advantages compared with the prior art: The battery cover plate, the method for preparing the battery cover plate, and the secondary battery involved in the present invention realize the function of automatically and spontaneously connecting the internal and external environments of the battery when the temperature and pressure inside the battery are increased by arranging pre-adjustment holes and pre-exhaust components on the main body. When the temperature and pressure inside the battery increase, the pre-exhaust component can respond quickly and open the connecting channel in time. This design fundamentally solves the problem of thermal runaway and explosion of the battery that may be caused by poor consistency of the explosion-proof holes in the prior art. Compared with the conventional battery cover plate structure at this stage, the battery cover plate structure of the present invention has higher safety in use and adaptive adjustability, and thus has extremely high practical value and market promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0019] Figure 1 It is a schematic diagram of the exploded structure of the battery cover in the preferred embodiment of the present invention; Figure 2 yes Figure 1 A schematic diagram of the three-dimensional structure of the battery cover shown; Figure 3 yes Figure 2 Schematic diagram of the cross-section structure at AA in the middle; Figure 4 yes Figure 3 The enlarged structural diagram at B in the middle; Figure 5 yes Figure 3 The enlarged structural diagram at C in the middle; Figure 6 yes Figure 3 The enlarged structural diagram at D in the middle; Figure 7 is a schematic diagram of the three-dimensional structure of a battery cover in another embodiment of the present invention; Figure 8 yes Figure 7 Schematic diagram of the cross-section structure at EE; Fig. 9 yes Figure 8 The enlarged structural diagram at F in the middle; Fig.10 It is a schematic diagram of the three-dimensional structure of a secondary battery in the third embodiment of the present invention.

[0020] Explanation of the reference numerals in the specification: 100, main body; 110, explosion-proof hole; 120, injection hole; 130, pre-adjustment hole; 140, expansion protrusion; 200, connection assembly; 210, pressure block; 220, upper plastic; 230, sealing ring; 240, lower plastic; 250, rivet; 251, plug-in part; 252, welding part; 253, limiting part; 300, pre-exhaust assembly; 310, insulation layer; 320, stop layer; 330, connection layer; 400, explosion-proof disk; 500, sealing nail; 600, shell. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention. Embodiment 1

[0022] See also Figure 1 and Figure 2As shown, the present embodiment provides a battery cover, which includes: a main body 100, on which an explosion-proof hole 110 and a pre-adjustment hole 130 are provided, and both the explosion-proof hole 110 and the pre-adjustment hole 130 penetrate the main body 100 along the thickness direction of the main body 100, wherein an explosion-proof plate 400 is provided in the explosion-proof hole 110; a pre-exhaust component 300, which is arranged corresponding to the pre-adjustment hole 130, and includes a stop layer 320 and a connecting layer 330 connected to each other, wherein one side of the connecting layer 330 is adhered to the main body 100, and the other side is connected to the stop layer 320, and the stop layer 320 covers the pre-adjustment hole 130; the connecting layer 330 melts when it reaches a preset melting point, so that the stop layer 320 is separated from the main body 100 and the pre-adjustment hole 130 is exposed.

[0023] The battery cover described in this embodiment realizes the function of automatically and spontaneously connecting the internal and external environments of the battery when the temperature and pressure inside the battery rise by setting the pre-adjustment hole 130 and the pre-vent assembly 300 on the body 100. When the temperature and pressure inside the battery rise, the pre-vent assembly 300 can respond quickly and open the connecting channel in time. This design fundamentally solves the problem of thermal runaway explosion of the battery that may be caused by poor consistency of the explosion-proof hole 110 in the prior art.

[0024] See also Figure 1 and Figure 2 As shown, in this embodiment, the explosion-proof hole 110 is used to install and connect the explosion-proof plate 400. In conventional battery structures, the production quality of the explosion-proof plate 400 is affected by many factors, such as wear of the stamping die and unstable welding parameters. Therefore, the explosion-proof plate 400 has consistency differences during actual use, and it is difficult to stably achieve the explosion-proof effect on the battery. In this embodiment, the provision of the pre-adjustment hole 130 enables the pre-exhaust assembly 300 to take effect before the explosion-proof plate 400 when the temperature and pressure rise, and ensures that the internal and external environments of the battery are connected before the internal pressure of the battery reaches the limit, thereby effectively controlling the internal air pressure of the battery, thereby fundamentally eliminating the risk of battery explosion. Furthermore, conventional battery structures such as a liquid injection hole 120 and a sealing nail 500 are also provided thereon.

[0025] Specifically, in this embodiment, a pre-adjustment hole 130 is provided on one side of the body 100. Correspondingly, in this embodiment, a pre-exhaust assembly 300 is provided. Specifically, see Figure 3 and Figure 4As shown, the stop layer 320 in the pre-exhaust assembly 300 can effectively stop the water vapor inside the shell 600, thereby achieving the sealing of the internal structure of the battery, and the connecting layer 330 is used to connect the stop layer 320 and the body 100, so that the stop layer 320 can completely cover the adjustment hole. Specifically, in order to improve the connection stability and sealing of the connecting layer 330, the surface area of ​​the connecting layer 330 in this embodiment is larger than the stop layer 320, and its substrate is preferably a polymer hot-melt material. Furthermore, its preset melting point is 100°C. Based on this, when the internal ambient temperature of the battery reaches 100°C, the connecting layer 330 can gradually melt under the action of high temperature and pressure until the stop layer 320 is separated from the pre-adjustment hole 130. In this embodiment, the substrate of the stop layer 320 is preferably a metal material with high thermal conductivity and high sealing. In different embodiments, the specific types of the connecting layer 330 and the stopping layer 320 can be adaptively adjusted according to actual usage requirements. The melting point of the connecting layer 330 is the preset melting point, which can be configured to 90~140°C based on the upper limit of the conventional battery temperature. The present invention does not impose specific restrictions on this.

[0026] Further, see Figure 4 As shown, the pre-exhaust component 300 in this embodiment also includes an insulating layer 310. The insulating layer 310 and the connecting layer 330 are respectively located on two opposite sides of the thickness direction of the stopping layer 320. In this embodiment, the insulating layer 310 is used to improve the safety of the pre-exhaust component 300 on the one hand, and to protect the stopping layer 320 on the other hand to avoid corrosion or oxidation of the stopping layer 320. The base material thereof may preferably be rubber, silicone, etc., and the present invention does not impose any specific limitation on this.

[0027] See also Figure 5 and Figure 6As shown, the connection assembly 200 in this embodiment includes a pressing block 210 and a rivet 250. The pressing block 210 is arranged on the body 100, and the rivet 250 is connected between the pressing block 210 and the body 100. The pressing block 210 is used to connect with the rivet 250 to achieve its assembly connection with the body 100, and at the same time fix the internal structure of the battery. In actual use, due to the large external force on the pressing block 210, warping will occur at the edge of the body 100. Based on this, the connection assembly 200 in this embodiment includes an upper plastic 220, a lower plastic 240 and a sealing ring 230. The upper plastic 220 and the lower plastic 240 are respectively arranged on both sides of the body 100 in the thickness direction, and the The upper plastic 220 is arranged between the body 100 and the pressing block 210, the rivet 250 is sequentially connected to the lower plastic 240, the body 100, the upper plastic 220 and the pressing block 210, and the rivet 250 and the lower plastic 240 are in contact with each other, and a sealed expansion space is enclosed between the rivet 250, the upper plastic 220, the body 100 and the lower plastic 240, and the sealing ring 230 is arranged around the rivet 250 and is located in the sealed expansion space. Through the setting of the expansion space, the sealing ring 230 in this embodiment can expand or contract inside the expansion space, especially during the use of the battery, the sealing ring 230 will absorb the electrolyte to expand twice, so the present application can not only achieve a high degree of sealing of the cover assembly, but also protect the sealing ring 230 and its surrounding structures.

[0028] Furthermore, the main body 100 in this embodiment is provided with an expansion protrusion 140, and the upper plastic 220 is provided with a receiving groove corresponding to the expansion protrusion 140, and the expansion protrusion 140 can be embedded in the receiving groove. Based on the above structural setting, the main body 100 can pass through the deformation in the expansion space even if the end thereof is squeezed by the pressing block 210, thereby ensuring the structural stability of the edge of the main body 100, thereby achieving the purpose of improving the stability and sealing of the battery connection.

[0029] In this embodiment, the rivet 250 includes an inserting portion 251, a welding portion 252 and a limiting portion 253, wherein the inserting portion 251 is arranged to penetrate and connect the pressure block 210, the upper plastic 220 and the main body 100, the welding portion 252 is arranged at one end of the inserting portion 251 away from the pressure block 210, and extends perpendicularly to the inserting portion 251, the limiting portion 253 is connected to the extended end of the welding portion 252, and the thickness of the limiting portion 253 is less than the thickness of the welding portion 252, so as to form a step surface at the connection between it and the welding portion 252, and the lower plastic 240 abuts against the step surface. Based on this, the rivet 250 can replace the traditional adapter to achieve the connection of the electrodes, thereby simplifying the internal structural setting of the battery. Furthermore, in order to avoid the occurrence of welding through, the present embodiment sets the welding part 252 as a thicker component and designs the limiting part 253 as a thinner component to improve the riveting stability of the rivet 250 and its degree of coordination with other structures. Based on the above structural setting, a step surface can also be formed between the welding part 252 and the limiting part 253 to improve the connection stability between it and the lower plastic 240. Embodiment 2

[0030] See also Figures 7 to 9 As shown, this embodiment provides another battery cover, whose main structure and working principle are the same as those of the first embodiment, and will not be elaborated here. In this embodiment, in order to reduce the space occupied by the pre-adjustment hole 130 on the main body 100, it is arranged between the pressing block 210 and the main body 100 to provide another feasible structural setting. Embodiment 3

[0031] This embodiment provides a method for preparing a battery cover plate, which is used to process and prepare the battery cover plate described in Embodiment 1, and includes: Step S1, adhere and connect the preformed stop layer 320 and the connecting layer 330 to obtain the pre-exhaust assembly 300; further, in this embodiment, it is also necessary to prepare the connection of the insulating layer 310, specifically: preform the insulating layer 310, the stop layer 320 and the connecting layer 330 respectively, and then connect the insulating layer 310 and the connecting layer 330 to the opposite sides of the thickness direction of the stop layer 320 respectively to obtain the pre-exhaust assembly 300. Among them, the insulating layer 310 can protect the stop layer 320 to prevent it from oxidative corrosion, and at the same time improve the safety of the battery cover. Specifically, in this embodiment, the pre-adjustment hole 130 is prepared by stamping the main body 100.

[0032] Step S2, placing the pre-exhaust component 300 at the pre-adjustment hole 130 of the main body 100, and making the connecting layer 330 adhere and connect to the main body 100; further, in this embodiment, before placing the pre-exhaust component 300 at the pre-adjustment hole 130 of the main body 100, the surface of the main body 100 is successively subjected to oil cleaning, nano-corrosion processing and passivation treatment to improve the cleanliness of the surface of the main body 100 and improve the connection stability between it and the pre-exhaust component 300.

[0033] Step S3, heat and pressurize the pre-exhaust component 300, maintain the first preset time and then stop; further, in this embodiment, the temperature for heating the pre-exhaust component 300 is 190°C, and the first preset time is 5s; in step S4, the second preset time is 0.1s, and in other embodiments, the temperature for heating the pre-exhaust component 300 can be configured to 190~230°C according to actual conditions, and the first preset time can be configured to 5~20s according to actual conditions; in step S4, the second preset time can be configured to 0.1~1.0s according to actual conditions, and the present invention does not make specific restrictions on this.

[0034] Step S4, high-frequency pressing is performed on the pre-exhaust component 300 to make the main body 100 and the stopping layer 320 self-heat, and the process is stopped after a second preset time. Furthermore, the heating and pressurizing in step S3 can achieve a preliminary connection between the pre-exhaust component 300 and the main body 100, and the heat is released from the insulating layer 310 side toward the connecting layer 330 side through an external heating element to achieve the purpose of rapid connection and fixation. However, in the above process, the heat penetrates the multi-layer structure in turn, and uneven temperature will appear between the multi-layer structures. Therefore, it is difficult to achieve the expected connection stability. Based on this, the present application adopts high-frequency pressing after heating and pressurizing to make the main body 100 and the stopping layer 320 self-heat under the action of high frequency, thereby achieving temperature homogenization, and then the connecting layer 330 can be fully connected to the main body 100 and the stopping layer 320, and at the same time, it can also achieve complete stopping coverage of the pre-exhaust port.

[0035] Step S5: leaving the main body 100 and the pre-exhaust assembly 300 still until they are cooled to obtain a target battery cover. Embodiment 4

[0036] See also Fig.10 As shown, this embodiment provides a secondary battery, which includes the battery cover, shell 600 and electrode group described in Example 1, the electrode group and electrolyte are arranged inside the shell 600, and the cover is connected to the opening of the shell 600 to seal the internal environment of the shell 600.

[0037] In summary, the battery cover, the method for preparing the battery cover, and the secondary battery involved in the present invention, by providing the pre-adjustment hole 130 and the pre-exhaust assembly 300 on the main body 100, realizes the function of automatically and spontaneously connecting the internal and external environments of the battery when the temperature and pressure inside the battery rise. When the temperature and pressure inside the battery increase, the pre-exhaust assembly 300 can respond quickly and open the connecting channel in time. This design fundamentally solves the problem of thermal runaway and explosion of the battery that may be caused by the poor consistency of the explosion-proof hole 110 in the prior art. Compared with the conventional battery cover structure at this stage, the battery cover structure of the present invention has higher safety in use and adaptive adjustability, and thus has extremely high practical value and market promotion prospects.

[0038] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A battery cover, characterized in that: include: A body, wherein an explosion-proof hole and a pre-adjustment hole are provided on the body, wherein the explosion-proof hole and the pre-adjustment hole both penetrate the body along the thickness direction of the body, wherein an explosion-proof sheet is provided in the explosion-proof hole; A pre-exhaust component is arranged corresponding to the pre-adjustment hole, and includes a stop layer and a connecting layer that are connected to each other, wherein one side of the connecting layer is adhered to the main body, and the other side is connected to the stop layer, and the stop layer covers the pre-adjustment hole; the connecting layer melts when it reaches a preset melting point, so that the stop layer is separated from the main body and the pre-adjustment hole is exposed.

2. The battery cover according to claim 1, characterized in that: The pre-exhaust component further includes an insulating layer, and the insulating layer and the connecting layer are respectively located on two opposite sides of the stopping layer in the thickness direction.

3. The battery cover according to claim 1, characterized in that: The preset melting point is 90-140° C., the connecting layer substrate is a polymer hot-melt material, and the stopping layer substrate is a metal.

4. The battery cover according to claim 1, characterized in that: The battery cover also includes a connecting component, which includes a pressing block and a rivet. The pressing block is arranged on the main body, and the rivet is penetrated to connect the pressing block and the main body.

5. The battery cover according to claim 4, characterized in that: The connecting component includes an upper plastic, a lower plastic and a sealing ring. The upper plastic and the lower plastic are respectively arranged on both sides of the body in the thickness direction, and the upper plastic is arranged between the body and the pressing block. The rivet is sequentially arranged to connect the lower plastic, the body, the upper plastic and the pressing block, and the rivet and the lower plastic are abutted against each other. A sealed expansion space is jointly enclosed by the rivet, the upper plastic, the body and the lower plastic. The sealing ring is arranged around the rivet and is located in the sealed expansion space.

6. The battery cover according to claim 5, characterized in that: The rivet comprises an inserting portion, a welding portion and a limiting portion, wherein the inserting portion is arranged to connect the pressure block, the upper plastic and the body, the welding portion is arranged at one end of the inserting portion away from the pressure block, and extends perpendicularly to the inserting portion, the limiting portion is connected to the extended end of the welding portion, and the thickness of the limiting portion is less than the thickness of the welding portion, so as to form a step surface at the connection between the limiting portion and the welding portion, and the lower plastic abuts against the step surface.

7. The battery cover according to claim 5, characterized in that: The main body is provided with an expansion-shaped protrusion, and the upper plastic is provided with an accommodating groove corresponding to the expansion-shaped protrusion, and the expansion-shaped protrusion can be embedded in the accommodating groove.

8. A method for preparing a battery cover, characterized in that: Used for processing and preparing the battery cover plate according to any one of claims 1 to 7, comprising: Step S1, bonding the preformed stopper layer and the connecting layer to obtain a pre-exhaust assembly; Step S2, placing the pre-exhaust assembly at the pre-adjustment hole of the body, and making the connection layer adhere to and connect with the body; Step S3, heating and pressurizing the pre-exhaust assembly, maintaining the heating and pressurizing process for a first preset time and then stopping; Step S4, performing high-frequency pressing on the pre-exhaust assembly to make the body and the stop layer self-heat, and then stopping after maintaining the heating for a second preset time; Step S5: leaving the main body and the pre-exhaust assembly to stand until they are cooled to obtain a target battery cover.

9. The method for preparing a battery cover according to claim 8, characterized in that: In step S1, the insulating layer, the stopping layer and the connecting layer are preformed respectively, and then the insulating layer and the connecting layer are connected to opposite sides of the stopping layer in the thickness direction to obtain a pre-exhaust component; at the same time, the main body is stamped to prepare a pre-adjustment hole.

10. The method for preparing a battery cover according to claim 8, characterized in that: In step S2, before the pre-exhaust assembly is placed at the pre-adjustment hole of the body, the surface of the body is sequentially subjected to oil cleaning, nano-corrosion processing and passivation treatment.

11. The method for preparing a battery cover according to claim 8, characterized in that: In step S3, the temperature for heating the pre-exhaust component is 190-230°C, and the first preset time is 5-20s; in step S4, the second preset time is 0.1-1.0s.

12. A secondary battery, characterized in that: The battery comprises a battery cover, a shell and an electrode group as described in any one of claims 1 to 7, wherein the electrode group and the electrolyte are arranged inside the shell, and the cover is connected to the shell opening to seal the internal environment of the shell.

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