Rechargeable batteries, battery packs, and electronic devices

Abstract

The present invention provides a secondary battery, a battery pack, and an electronic device that can improve upon the technical problem of poor end cover design flexibility in existing secondary batteries. [Solution] The secondary battery includes a housing and an electrode assembly, the housing includes a side wall having an opening at one end and a cover plate assembly, the cover plate assembly sealing the opening and the electrode assembly being installed inside the housing. Here, the cover plate assembly includes a first cover plate and a second cover plate, the first cover plate covering the opening and sealed to the side wall, the first cover plate including a through hole, the second cover plate at least partially blocking the through hole and the second cover plate being connected to the first cover plate.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and particularly to secondary batteries, battery packs, and electronic devices.

Background Art

[0002] Existing secondary batteries generally install an end cover at the open end of the housing to seal the opening. Current end covers are usually of an integral design such as an integral press-forming structure. When fitting and installing the end cover with other components, various structural features such as local depressions, local grooves, apertures, etc. often have to be incorporated into local regions on the end cover to meet the corresponding fitting and mounting requirements. Due to limitations in the forming process and processing costs, etc. of the integral design end cover, when forming a plurality of different structural features, there are often problems such as difficulties in primary forming and poor forming accuracy, etc., thereby deteriorating the flexibility of the end cover design and restricting the structural optimization on the end cover side.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The present invention provides a secondary battery, a battery pack, and an electronic device that can improve the technical problem of the poor flexibility of the existing end cover design of secondary batteries.

Means for Solving the Problems

[0004] To achieve the above-mentioned and other related objectives, the present invention provides a secondary battery. The secondary battery includes a housing and an electrode assembly. The housing includes a side wall having an opening at one end and a cover plate assembly, the cover plate assembly sealing the opening. The electrode assembly is installed inside the housing. Here, the cover plate assembly includes a first cover plate and a second cover plate, the first cover plate covering the opening and sealed to the side wall. The first cover plate includes a through hole. The second cover plate at least partially blocks the through hole. The second cover plate is connected to the first cover plate.

[0005] In one embodiment of the secondary battery of the present invention, the second cover plate includes a liquid injection hole, is positioned between the first cover plate and the electrode assembly, and fits with the inner wall of the through hole to form a step, and the cover plate assembly further includes a sealing plate. The outer edge of the sealing plate fits with the step and is welded to the inner wall of the through hole to seal the liquid injection hole.

[0006] In one embodiment of the secondary battery of the present invention, the secondary battery further includes a current collector member electrically connected to an electrode assembly, the current collector member being positioned between the electrode assembly and a second cover plate, welded to the second cover plate to form a first weld, and a sealing plate covering and sealing the first weld.

[0007] In one embodiment of the secondary battery of the present invention, the first cover plate further includes a first protrusion and a cover portion positioned to surround the outer circumference of the first protrusion, wherein the first protrusion projects toward the second cover plate relative to the cover portion, a through hole passes through the first protrusion, and one side of the first protrusion facing the electrode assembly is welded to the second cover plate.

[0008] In one embodiment of the secondary battery of the present invention, one side of the first protrusion away from the electrode assembly includes a first recess, the sealing plate is welded to the inner wall of the through hole to form a second weld, the second weld is housed within the first recess, and the top of the second weld does not extend beyond the outer surface of the cover away from the electrode assembly.

[0009] In one embodiment of the secondary battery of the present invention, the secondary battery further includes a current collector, which is mounted on one side of the electrode assembly facing the cover plate assembly and is electrically connected to the electrode assembly. The outer edge of the first cover plate is welded to the side wall, and at least a portion of the current collector is exposed to the through hole, and the portion of the second cover plate that blocks the through hole is at least partially welded to the current collector.

[0010] In one embodiment of the secondary battery of the present invention, the second cover plate is installed on one side of the first cover plate away from the electrode assembly, and the outer edge of the second cover plate is welded in contact with the first cover plate.

[0011] In one embodiment of the secondary battery of the present invention, a second cover plate is welded to a current collector to form a first weld mark, the first weld mark penetrating the second cover plate and entering the interior of the current collector, but not exceeding the surface of the current collector facing the electrode assembly. The second cover plate is welded to the first cover plate to form a third weld mark, the third weld mark penetrating the second cover plate and entering the interior of the first cover plate, but not exceeding the surface of the first cover plate facing the electrode assembly.

[0012] In one embodiment of the secondary battery of the present invention, the first cover plate includes a second recess and a cover portion positioned to surround the outer circumference of the second recess, the second recess being recessed toward the electrode assembly side relative to the cover portion, the second recess including a bottom wall, a through hole penetrating the bottom wall, and the second cover plate being housed in the second recess and welded to the bottom wall.

[0013] In one embodiment of the secondary battery of the present invention, the melting point of the second cover plate is greater than the melting point of the current collector and less than the melting point of the first cover plate.

[0014] In one embodiment of the secondary battery of the present invention, the material of the second cover plate is one of nickel, carbon steel, iron, copper, copper-nickel alloy, or iron-nickel alloy.

[0015] In one embodiment of the secondary battery of the present invention, the thickness of the second cover plate is less than the thickness of the first cover plate.

[0016] In one embodiment of the secondary battery of the present invention, along the axial direction of the secondary battery, the current collector member includes a current collector body and a thicker portion than the current collector body, the thicker portion protruding toward the second cover plate side relative to the current collector body and contacting and welding to the second cover plate.

[0017] In one embodiment of the secondary battery of the present invention, the thickness of the second cover plate is less than the thickness of the thickened portion.

[0018] In one embodiment of the secondary battery of the present invention, the ratio of the inner diameter of the through hole to the outer diameter of the first cover plate is 0.5 or less.

[0019] In one embodiment of the secondary battery of the present invention, the secondary battery further includes a current collector, which is mounted on one side of the electrode assembly facing the cover plate assembly and is electrically connected to the electrode assembly to form a fourth weld. Along the axial direction of the secondary battery, the orthographic projection of the first cover plate covers at least partially the fourth weld.

[0020] In one embodiment of the secondary battery of the present invention, the cover plate assembly further includes an explosion-proof notch, the explosion-proof notch being provided on the first cover plate.

[0021] The present invention further provides a battery pack which includes a secondary battery in any of the embodiments described above.

[0022] The present invention further provides an electronic device, which includes the battery pack described above. [Effects of the Invention]

[0023] The secondary battery, battery pack, and electronic device provided by the present invention include a cover plate assembly of the secondary battery comprising a first cover plate and a second cover plate, which are installed separately. The first and second cover plates can be individually molded and then fixed together. Compared to an integrated end cover design, this design allows for an optimized layout of multiple local feature structures on the cover plate assembly by adjusting the connection position relationship between the first and second cover plates, and facilitates the processing and molding of local features. Furthermore, because the first and second cover plates are installed as separate structures, the first and second cover plates can be made of different materials or have different thicknesses depending on the actual welding and strength requirements. Therefore, compared to an integrated end cover design, the separate design of the cover plate assembly in the present invention offers superior flexibility and further facilitates structural optimization on the end cover side of the secondary battery. [Brief explanation of the drawing]

[0024] To more clearly illustrate embodiments of the present invention or technical solutions in the prior art, the accompanying drawings that may be used in the description of embodiments or prior art are briefly introduced below. Clearly, the accompanying drawings in the following description represent only a few embodiments of the present invention, and a person of ordinary skill in the art can derive other embodiments from these accompanying drawings without any creative effort.

[0025] [Figure 1]It is a cross-sectional view of the overall structure of one embodiment of the secondary battery of the present invention. [Figure 2] It is a partially enlarged view of region A in FIG. 1. [Figure 3] It is a partially enlarged view of the attachment positions of the first cover plate and the second cover plate in one embodiment of the secondary battery of the present invention. [Figure 4] It is a schematic view of the three-dimensional structure of the first cover plate in one embodiment of the secondary battery of the present invention. [Figure 5] It is a partial cross-sectional view of the first cover plate in one embodiment of the secondary battery of the present invention. [Figure 6] It is a schematic view of the cover plate assembly in one embodiment of the secondary battery of the present invention. [Figure 7] It is a cross-sectional view of the cover plate assembly in one embodiment of the secondary battery of the present invention. [Figure 8] It is a schematic view of the attachment positions of the first cover plate and the second cover plate in one embodiment of the secondary battery of the present invention. [Figure 9] It is a schematic view of the welding positions of the first cover plate and the second cover plate in another embodiment of the secondary battery of the present invention. [Figure 10] It is a schematic view of the structure of the thick portion and the second cover plate in one embodiment of the secondary battery of the present invention. [Figure 11] It is a partially enlarged view of the attachment position of the thick portion and the second cover plate in one embodiment of the secondary battery of the present invention. [Figure 12] It is a schematic view of the overall structure of one embodiment of the battery pack of the present invention. [Figure 13] It is a schematic view of the structure when the battery pack of the present invention is attached to a vehicle.

Embodiments for Carrying out the Invention

[0026] The embodiments of the present invention will be described below through specific examples, but those skilled in the art will readily understand other advantages and effects of the present invention from what is disclosed herein. The present invention may also be implemented or applied through other different specific embodiments, and each detail herein may be modified or changed in various ways based on different viewpoints and applications, as long as it does not deviate from the spirit of the invention. It should be noted that the embodiments and features within the embodiments below may be combined with each other, where there is no contradiction. It should also be understood that the terms used in the embodiments of the present invention are for the purpose of describing specific implementations and are not intended to limit the scope of protection of the present invention. In the embodiments below, test methods for which specific conditions are not specified shall generally follow conventional conditions or conditions proposed by various manufacturers.

[0027] When numerical ranges are given in embodiments, it should be understood that, unless otherwise stated in the present invention, any two endpoints of each numerical range and any numerical values ​​between those two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art in relation to the prior art, and any prior art methods, apparatus, and materials similar or equivalent to those described in embodiments of the present invention may be used in carrying out the present invention.

[0028] It should be noted that terms such as "up," "down," "left," "right," "middle," and "one" used herein are for the purpose of clarifying the explanation and are not used to limit the scope within which the present invention can be implemented. Any changes or adjustments to their relative relationships should be considered within the scope within which the present invention can be implemented, provided that there is no substantial change in the technical content.

[0029] Referring to Figures 1 to 13, the present invention provides a secondary battery 100, a battery pack 200, and an electronic device 300. The cover plate assembly 140 of the secondary battery 100 includes a first cover plate 141 and a second cover plate 142, the second cover plate 142 being fixedly connected to the first cover plate 141, and furthermore, the cover plate assembly 140 achieves a separate design, and compared to an integrated end cover design, such a design can improve the design flexibility of the cover plate assembly 140.

[0030] In the present invention, the secondary battery 100 may include a lithium-ion battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, but the embodiments of the present invention are not limited thereto. The secondary battery 100 may have a cylindrical shape, a flattened shape, a rectangular prism, or other shapes, but the embodiments of the present invention are not limited thereto.

[0031] Referring to Figures 1 and 2, the structure of the secondary battery 100 will be further described, which includes a housing 110 and an electrode assembly 120.

[0032] A mounting cavity is formed inside the housing 110 and is used to mount the electrode assembly 120, electrolyte (not shown), and other components. Specifically, the dimensions of the housing 110 can be determined based on the specific dimensions of the electrode assembly 120, for example, the diameter can be 46 mm and the height can be 80 mm, 95 mm, 120 mm, etc. The housing 110 may have various shapes, for example, it may be cylindrical, prismatic, etc. The material of the housing 110 may also vary, for example, it may be copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the housing 110 from rusting during long-term use, an additional layer of rust-preventive material such as metallic nickel may be plated onto the surface of the housing 110.

[0033] Referring to Figures 1 and 2, in one embodiment of the secondary battery 100 of the present invention, the housing 110 is a cylindrical structure and includes an end wall 113, a side wall 111 surrounding the end wall 113, and a cover plate assembly 140. Along the height direction of the housing 110, one end of the side wall 111 is fixedly connected to the end wall 113 to form a closed end, and an opening 112 is provided at the other end of the side wall 111. The cover plate assembly 140 is placed over the opening 112 and seals the opening 112.

[0034] As shown in Figures 1 and 2, the electrode assembly 120 is housed within the housing 110. The electrode assembly 120 is a component in the secondary battery 100 where electrochemical reactions occur. The electrode assembly 120 is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and a separator is usually placed between the positive electrode sheet and the negative electrode sheet. Preferably, in this embodiment, the electrode assembly 120 is formed by winding a positive electrode sheet, a negative electrode sheet, and a separator. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer being coated on the surface of the positive electrode current collector. The positive electrode current collector includes a positive electrode coating region and a positive electrode tab connected to the positive electrode coating region, the positive electrode active material layer being coated on the positive electrode coating region and not on the positive electrode tab. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer being coated on the surface of the negative electrode current collector. The negative electrode current collector includes a negative electrode coating region and a negative electrode tab connected to the negative electrode coating region. The negative electrode coating region is coated with a negative electrode active material layer, while the negative electrode tab is not coated with the negative electrode active material layer. Taking a lithium-ion battery as an example, the material of the positive electrode current collector may be aluminum, and the positive electrode active material layer may contain a positive electrode active material, which may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The material of the negative electrode current collector may be copper, and the negative electrode active material layer may contain a negative electrode active material, which may be carbon or silicon, etc. The main substrate of the separator may be PP or PE, etc. In order to provide protection and insulation to the electrode assembly 120, an insulating film may be further coated on the outside of the electrode assembly 120, and the insulating film can be synthesized from PP, PE, PET, PVC, or other polymer materials.

[0035] Continuing to refer to Figures 1 and 2, in one embodiment of the secondary battery 100 of the present invention, the electrode assembly 120 is sealed and mounted inside the housing 110. The electrode assembly 120 has a first tab 121 and a second tab 122 at both ends in the height direction of the secondary battery 100, and the first tab 121 and the second tab 122 have opposite polarities. Here, the first tab 121 faces the opening 112 of the housing 110, and the first tab 121 is the negative electrode tab. It should be noted that in other embodiments, the first tab 121 may be the positive electrode tab and the second tab 122 may be the negative electrode tab.

[0036] Referring to Figure 1, in one embodiment of the secondary battery 100 of the present invention, a terminal mounting hole is provided that penetrates the end wall 113 of the housing 110, and the electrode terminal 170 penetrates the terminal mounting hole, sealing and insulating the inside of the hole. However, the method of mounting the electrode terminal 170 on the end wall 113 is not limited as long as sealing and insulation between the electrode terminal 170 and the end wall 113 can be achieved. One side of the electrode assembly 120 facing the end wall 113 has a second tab 122, and one end of the electrode terminal 170 may be directly welded to the second tab 122, or conductively connected to the second tab 122 via a current collector, but this is not specifically limited in the present invention.

[0037] Referring to Figures 1 and 2, in one embodiment of the secondary battery 100 of the present invention, the current collector 130 is installed inside the housing 110 and is located on one side of the electrode assembly 120 facing the cover plate assembly 140, and the current collector 130 is welded to the first tab 121 and the housing 110, respectively, to achieve electrical connection. The current collector 130 may be welded to the cover plate assembly 140, or to the side wall 111, or may be welded to the cover plate assembly 140 and the side wall 111 simultaneously. The specific location and welding area of ​​the welding between the current collector 130 and the first tab 121 are not limited, as long as a stable electrical connection requirement between the current collector 130 and the first tab 121 can be achieved.

[0038] It should be noted that in some other embodiments, the current collector 130 does not need to be installed between the cover plate assembly 140 and the electrode assembly 120, and the cover plate assembly 140 is directly welded to the first tab 121 on the electrode assembly 120 and simultaneously welded to the side wall 111, further enabling an electrical connection between the electrode assembly 120 and the housing 110.

[0039] Referring to Figures 2 to 5, the cover plate assembly 140 includes a first cover plate 141 and a second cover plate 142. The first cover plate 141 covers the opening 112, and the outer edge of the first cover plate 141 is sealed to the side wall 111 of the housing 110. The method of sealing connection may vary, for example, welding, mechanical pressure sealing, etc. The first cover plate 141 includes a through hole 1411, which may be located in the central region of the first cover plate 141 or offset from the central region. The shape of the through hole 1411 may also vary, for example, a square hole, a circular hole, or other irregularly shaped hole, etc. Preferably, in this embodiment, to facilitate machining and positioning of the through hole 1411 on the first cover plate 141, the through hole 1411 is a circular hole structure and is installed coaxially with the first cover plate 141.

[0040] Referring to Figures 3, 6, and 7, the second cover plate 142 is installed on one side away from the electrode assembly of the current collector member 130, and the second cover plate 142 blocks at least partially the through hole 1411. The second cover plate 142 is connected to the first cover plate 141, and the connection method may be any method that can achieve electrical connection between the first cover plate 141 and the second cover plate 142, such as welding or riveting.

[0041] Referring to Figures 2, 6, and 7, preferably in this embodiment, the first cover plate 141 and the second cover plate 142 are welded together. The second cover plate 142 may be a disc shape that aligns with the through hole 1411, or it may be another shape that can at least partially block the through hole 1411, such as a rectangular plate or a polygonal plate. Preferably in this embodiment, the second cover plate 142 has a substantially disc-shaped structure and is installed coaxially with the through hole 1411. This makes positioning and mounting between the second cover plate 142 and the first cover plate 141 convenient, and is therefore advantageous in improving the assembly efficiency between the second cover plate 142 and the first cover plate 141.

[0042] The mounting position between the second cover plate 142 and the first cover plate 141 can be changed according to different design requirements. For example, the second cover plate 142 may be mounted on one side of the first cover plate 141 away from the electrode assembly to form a housing cavity feature on the cover plate assembly 140 that opens toward the electrode assembly 120. This allows some of the features of the current collector 130 to be accommodated in the axial direction, which is convenient for welding between the current collector 130 and the second cover plate 142. Alternatively, the second cover plate 142 may be mounted on one side of the first cover plate 141 facing the electrode assembly 120 to form a stepped feature on the cover plate assembly 140 that faces the outside of the cover plate assembly 140. This makes it convenient to form a mating positioning relationship with components connected to the outside of the cover plate assembly 140. The materials of the first cover plate 141 and the second cover plate 142 can be selected according to the welding requirements and connection strength at each location. For example, when the second cover plate 142 needs to be welded to the first cover plate 141 and the current collector 130 simultaneously, the second cover plate 142 can be made of a material whose melting point is between that of the first cover plate 141 and the current collector 130. This ensures the welding quality between the first cover plate 141 and the second cover plate 142, and also ensures the welding quality between the second cover plate 142 and the current collector 130. The thicknesses of the first cover plate 141 and the second cover plate 142 may be designed to be different to accommodate the different strength and welding requirements at each connection location. For example, since the first cover plate 141 needs to withstand relatively high strength and pressure, it must have a relatively large thickness. Furthermore, when it is necessary to weld the second cover plate 142 to the lower current collector member 130, a relatively small thickness can be used to facilitate penetration welding.

[0043] In this embodiment, the cover plate assembly 140 includes a first cover plate 141 and a second cover plate 142, which are installed separately. Therefore, the first cover plate 141 and the second cover plate 142 can be molded individually and then fixed together. Compared to an integrated end cover design, this design allows for an optimized layout of multiple local feature structures on the cover plate assembly 140 by adjusting the connection position between the first cover plate 141 and the second cover plate 142, and facilitates the processing and molding of local features. Furthermore, by installing the first cover plate 141 and the second cover plate 142 as separate structures, the first cover plate 141 and the second cover plate 142 can be made of different materials or have different thicknesses depending on the actual welding and strength requirements. Therefore, compared to an integrated end cover design, the separate design of the cover plate assembly 140 in this embodiment offers superior flexibility and further facilitates the structural optimization on the end cover side of the secondary battery 100.

[0044] Referring to Figures 2, 3, and 7, in one embodiment of the secondary battery 100 of the present invention, the second cover plate 142 includes an electrolyte injection hole 1421, which may be located in the central region of the second cover plate 142 or in a region offset from the center of the second cover plate 142, provided that it can satisfy the electrolyte injection requirements of the electrode assembly 120. The secondary battery 100 further includes a sealing plate 150, which is installed on one side of the second cover plate 142 away from the current collector 130, and the sealing plate 150 covers and seals the electrolyte injection hole 1421. Along the axial direction of the secondary battery 100, the second cover plate 142 is installed between the first cover plate 141 and the current collector 130. The outer edge of the second cover plate 142 abuts against the outer edge of one side of the through hole 1411 facing the electrode assembly 120. As shown in Figure 7, the second cover plate 142 fits with the inner wall of the through hole 1411 to form a step 180. The outer edge of the sealing plate 150 is housed within the step 180 and fits with the step 180. The outer edge of the sealing plate 150 abuts against the inner wall of the through hole 1411 to form a butt joint 160 that surrounds the circumferential direction of the through hole 1411, and a second weld mark 161 is formed at the position of the butt joint 160. The sealing plate 150 is welded to the inner wall of the through hole 1411 via the second weld mark 161, thereby sealing the liquid injection hole 1421. The positional fitting between the second cover plate 142 and the through hole 1411 allows for the formation of a step 180, thereby enabling the sealing plate 150 to be mounted within the step 180 and achieving the fitting and mounting of the sealing plate 150 on the cover plate assembly 140. This eliminates the need to integrally press-form the step 180 on the first cover plate 141 or the second cover plate 142. As a result, the molding accuracy of the step 180 can be improved, and the fitting accuracy between the sealing plate 150 and the step 180 can be improved. Ultimately, this improves the welding quality between the sealing plate 150 and the step 180, and reliably guarantees the sealing performance of the sealing plate 150 with respect to the liquid injection hole 1421.

[0045] Furthermore, referring to Figures 2 and 3, in one embodiment of the secondary battery 100 of the present invention, the orthographic projection of the current collector 130 is located at least partially within the projection of the through hole 1411 along the axial direction of the secondary battery 100. The surface of the second cover plate 142 facing the current collector 130 is at least partially welded to the lower current collector 130 to form a first weld mark 1422, and a sealing plate 150 located on one side of the second cover plate 142 away from the electrode assembly 120 covers and seals the first weld mark 1422. With such an installation, the sealing plate 150 can seal the liquid injection hole 1421 and at the same time cover and seal the first weld mark 1422, and further reduce the probability of corrosion occurring at the first weld mark 1422, thereby ensuring the stability of the electrical connection between the current collector 130 and the second cover plate 142.

[0046] Referring to Figures 3 to 5, in one embodiment of the secondary battery 100 of the present invention, the first cover plate 141 further includes a cover portion 1413 and a first protrusion 1412, wherein the cover portion 1413 is positioned to surround the outer circumference of the first protrusion 1412. Along the axial direction of the secondary battery 100, the first protrusion 1412 projects toward the second cover plate 142 relative to the cover portion 1413. The first protrusion 1412 may be located in the central region of the first cover plate 141 or in the edge region of the first cover plate 141, but preferably, in this embodiment, the first protrusion 1412 is located in the central region of the first cover plate 141. This makes it convenient to position the first protrusion 1412 on the first cover plate 141. The through-hole 1411 penetrates the first protrusion 1412 along the axial direction of the secondary battery 100. The through-hole 1411 may be installed coaxially with the first protrusion 1412 or on a different axis, but preferably, in this embodiment, the through-hole 1411 is installed coaxially with the first protrusion 1412. This makes it convenient to position the through-hole 1411 on the first cover plate 141. One side of the first protrusion 1412 facing the electrode assembly 120 is welded to the surface of the second cover plate 142 that is away from the electrode assembly 120. By installing the first protrusion 1412 and welding the edge region of the first protrusion 1412 to the second cover plate 142, local contact between the first cover plate 141 and the second cover plate 142 can be achieved. This improves the effective contact area between the first cover plate 141 and the second cover plate 142 at the edge of the through hole 1411, and further improves the welding quality of the first cover plate 141 and the second cover plate 142 at that location.

[0047] Referring to Figure 3, in one embodiment of the secondary battery 100 of the present invention, along the axial direction of the secondary battery 100, one side of the first protrusion 1412 away from the electrode assembly 120 includes a first recess 14121, the first recess 14121 being positioned to surround the outer circumference of the through hole 1411. A second weld mark 161, formed by welding the outer edge of the sealing plate 150 to the inner wall of the through hole 1411, is located within the first recess 14121, and the top of the second weld mark 161 does not extend beyond the outer surface of the cover portion 1413 on one side away from the electrode assembly 120. By positioning the second weld mark 161 within the first recess 14121, the probability of the second weld mark 161 protruding from the outer surface of the cover portion 1413 can be reduced, thereby ensuring the flatness of the outer end surface of the cover plate assembly 140. This not only makes it convenient to weld other conductive components to the end surface of the cover plate assembly 140, but also provides better protection for the second weld mark 161, reducing the probability of it being damaged by impact. In addition, since the first recess 14121 is positioned on one side of the first convex portion 1412 away from the electrode assembly 120, it is convenient for one-time press forming of the first convex portion 1412 and the first recess 14121, which is advantageous in reducing processing costs.

[0048] Referring to Figures 7 and 8, in one embodiment of the secondary battery 100 of the present invention, the outer edge of the first cover plate 141 includes a second protrusion 1415 that aligns with the opening 112, and the second protrusion 1415 is positioned to surround the outer edge of the cover portion 1413. The second protrusion 1415 projects toward the electrode assembly 120. Along the radial direction of the secondary battery 100, one side wall of the second protrusion 1415 away from the cover portion 1413 is welded to the inner surface of the side wall 111. Along the axial direction of the secondary battery 100, one surface of the second protrusion 1415 facing the electrode assembly 120 is welded in contact with the current collector member 130, forming a sixth weld mark 1416 as shown in Figure 8, thereby realizing an electrical connection between the current collector member 130 and the cover plate assembly 140. By installing the second protrusion 1415 and welding the second protrusion 1415 to the current collector member 130, the welding position between the current collector member 130 and the cover plate assembly 140 can be moved away from the electrolyte injection hole 1421 in the radial direction of the secondary battery 100. In this way, the probability of welding slag from the surface of the current collector member 130 entering the inside of the electrode assembly 120 together with the electrolyte during the electrolyte injection process can be reduced, and furthermore, the normal circulation of the electrolyte inside the electrode assembly 120 can be ensured.

[0049] Referring to Figure 3, in one embodiment of the secondary battery 100 of the present invention, along the axial direction of the secondary battery 100, at least a portion of the area of ​​the current collector member 130 is exposed to the through hole 1411, and at least a portion of the area where the second cover plate 142 blocks the through hole 1411 is welded to the current collector member 130, forming a first weld mark 1422 as shown in Figure 3. The number and shape trajectory of the first weld marks 1422 are not limited, as long as it is ensured that the first weld marks 1422 are located within the through hole 1411 and that the welding head can penetrate weld on one side of the second cover plate 142 away from the electrode assembly 120. By welding the second cover plate 142 to the current collector member 130, the thickness of the second cover plate 142 can be controlled, thereby optimizing the penetration welding process between the second cover plate 142 and the current collector member 130. Furthermore, during the welding process, the mass of the first weld marks 1422 can be guaranteed, while simultaneously reducing the probability of the current collector member 130 melting through. At the same time, since the second cover plate 142 and the first cover plate 141 are installed separately, any change in the thickness of the second cover plate 142 does not affect the thickness of the first cover plate 141, thereby ensuring the pressure resistance and support strength of the first cover plate 141.

[0050] Referring to Figures 9 to 11, in one embodiment of the secondary battery 100 of the present invention, the second cover plate 142 is installed along the axial direction of the secondary battery 100 on one side of the first cover plate 141 away from the electrode assembly 120, and the second cover plate 142 at least partially blocks the through hole 1411. The outer edge of the second cover plate 142 is welded to the surface of the first cover plate 141 on the side away from the electrode assembly 120. It should be noted that in this embodiment, at least a portion of the side of the second cover plate 142 facing the current collector 130 may be welded to the lower current collector 130. In other embodiments, the side of the second cover plate 142 facing the current collector 130 may not be welded to the lower current collector 130. This configuration allows welding operations to be performed on the outside of the first cover plate 141, between the first cover plate 141 and the second cover plate 142. This reduces the probability of foreign matter such as welding slag generated in the welding area entering the inside of the electrode assembly 120, which is further advantageous in ensuring the cleanliness of the internal environment of the electrode assembly 120. At the same time, when welding the central region of the second cover plate 142 to the lower current collector member 130, welding is also performed on the outside of the electrode assembly 120. This also reduces the probability of foreign matter such as welding slag generated during the welding process at that location entering the inside of the electrode assembly 120.

[0051] Furthermore, referring to Figures 9 to 11, in one embodiment of the secondary battery 100 of the present invention, a first weld mark 1422 is formed by penetration welding between the second cover plate 142 and the current collector member 130 on one side of the second cover plate 142 away from the electrode assembly 120 along the axial direction of the secondary battery 100. The first weld mark 1422 penetrates the second cover plate 142 and enters the interior of the current collector member 130, but does not extend beyond the surface of the current collector member 130 facing the electrode assembly 120. In other words, the first weld mark 1422 does not melt through the current collector member 130, as shown in Figure 11. A third weld mark 1423 is formed by penetration welding between the second cover plate 142 and the first cover plate 141 on one side of the second cover plate 142 away from the electrode assembly 120. The third weld mark 1423 penetrates the second cover plate 142 and enters the interior of the first cover plate 141, but does not extend beyond the surface of the first cover plate 141 facing the electrode assembly 120. In other words, the third weld mark 1423 does not melt through the first cover plate 141, as shown in Figure 11. This configuration further ensures that the first weld mark 1422 does not melt through the current collector 130 and the third weld mark 1423 does not melt through the first cover plate 141. This further reduces the probability of foreign matter such as welding slag generated during the welding process between the second cover plate 142 and the current collector 130, and between the second cover plate 142 and the first cover plate 141, entering the interior of the electrode assembly 120, thereby further guaranteeing the service life of the secondary battery 100.

[0052] To reduce the mounting dimensions occupied by the second cover plate 142 in the height direction of the secondary battery 100, referring to Figure 11, in one embodiment of the secondary battery 100 of the present invention, the first cover plate 141 includes a second recess 1414 and a cover portion 1413, the cover portion 1413 being installed to surround the outer circumference of the second recess 1414, and the second recess 1414 recesses toward the electrode assembly 120 side relative to the cover portion 1413. The second recess 1414 may have various shapes, such as a rectangular or cylindrical shape. To facilitate positioning molding, in this embodiment, the second recess 1414 has a cylindrical structure and is installed coaxially with respect to the cover portion 1413. The second recess 1414 includes a bottom wall 14141, and the through hole 1411 penetrates the bottom wall 14141. The through-hole 1411 may be located in the central region of the bottom wall 14141 or in the edge region of the bottom wall 14141, but preferably, in order to facilitate the forming process of the through-hole 1411 on the bottom wall 14141, in this embodiment the through-hole 1411 is located in the central region of the bottom wall 14141 and is located coaxially with the second recess 1414. The second cover plate 142 is housed in the second recess 1414, and in the depth direction of the second recess 1414, the second cover plate 142 may be completely housed in the second recess 1414 or partially housed in the second recess 1414, but the present invention is not limited thereto. The outer edge of the second cover plate 142 is welded in contact with the outer edge of the bottom wall 14141 to form a third weld mark 1423. By providing the second recess 1414 and housing the second cover plate 142 within the second recess 1414, the height space occupied by the secondary battery 100 when attaching the second cover plate 142 to the first cover plate 141 can be reduced, which is advantageous for improving the volumetric energy density of the secondary battery 100.

[0053] To further reduce the height dimension of the secondary battery 100, continuing to refer to Figure 11, in one embodiment of the secondary battery 100 of the present invention, the sealing plate 150 is installed on one side of the second cover plate 142 away from the electrode assembly 120 and is housed in the second recess 1414. The outer circumferential surface of the sealing plate 150 fits with the side wall of the second recess 1414, and the end face of the sealing plate 150 facing the electrode assembly 120 is welded to the second cover plate 142 at least partially, forming a fifth weld mark 162. Along the axial direction of the secondary battery 100, the sealing plate 150 simultaneously blocks the first weld mark 1422 and the third weld mark 1423, and further reduces the probability of corrosion occurring at the first weld mark 1422 and the third weld mark 1423, thereby ensuring stable weld quality. It should be explained that when the second cover plate 142 is provided with an injection hole 1421, the sealing plate 150 can further seal the injection hole 1421.

[0054] In a secondary battery, considering that the current collector 130 is mainly used for current guidance, the current collector 130 needs to have excellent current guidance performance and chemical corrosion resistance. However, the cover plate needs to be welded to the side wall 111 to form part of the housing 110, so it needs to have high strength and excellent rust prevention performance. In view of this, the current collector 130 and the cover plate are not basically made of the same material. The current collector 130 is generally made of materials such as copper, nickel, or aluminum, while the cover plate is generally made of stainless steel. As a result, welding the current collector 130 and the cover plate is difficult, and problems arise such as difficulty in welding and difficulty in guaranteeing welding quality. Referring to Figure 3, in one embodiment of the secondary battery 100 of the present invention, the melting point of the second cover plate 142 is greater than the melting point of the current collector 130 and less than the melting point of the first cover plate 141. By making the melting point of the second cover plate 142 higher than that of the current collector 130 and lower than that of the first cover plate 141, this installation allows the melting point of the second cover plate 142 to fall between that of the first cover plate 141 and the current collector 130. This reduces the difference in melting points between the second cover plate 142 and the first cover plate 141, thereby ensuring the quality of the weld between the second cover plate 142 and the first cover plate 141. Furthermore, it also reduces the difference in melting points between the second cover plate 142 and the current collector 130, ensuring the quality of the weld between the second cover plate 142 and the current collector 130. This effectively solves the problem of high welding difficulty and difficulty in guaranteeing welding quality between the current collector 130 and the cover plate.

[0055] Considering the commonly used material properties of the first cover plate 141 and the current collector 130, preferably, in one embodiment of the secondary battery 100 of the present invention, the material of the second cover plate 142 is one of nickel, carbon steel, iron, copper, copper-nickel alloy, or iron-nickel alloy. The above materials not only allow the melting point of the second cover plate 142 to be between that of the first cover plate 141 and the current collector 130, but at the same time, the above materials can also ensure that the second cover plate 142 has excellent conductivity and corrosion resistance.

[0056] In one embodiment of the secondary battery 100 of the present invention, the thickness of the second cover plate 142 is smaller than the thickness of the first cover plate 141. The difference in thickness between the first cover plate 141 and the second cover plate 142 affects the strength of the cover plate assembly 140 at different locations. As shown in Figure 3, the first cover plate 141 and the second cover plate 142 are installed in different locations, and therefore the requirements for strength and rigidity of the first cover plate 141 and the second cover plate 142 are also different. The first cover plate 141 is welded to the side wall 111 of the housing 110 and is subjected to greater pressure when the secondary battery 100 expands and deforms, so the support strength and rigidity of the first cover plate 141 need to be increased to suppress deformation of the secondary battery 100. Therefore, the thickness of the first cover plate 141 is also increased accordingly. Also, since the second cover plate 142 is located in the central region of the first cover plate 141, it deforms less than the first cover plate 141 when the secondary battery 100 expands and deforms. Therefore, the second cover plate 142 can be made with a relatively small thickness. This installation allows for a reduction in the weight of the second cover plate 142, provided that both the first cover plate 141 and the second cover plate 142 meet their respective strength requirements, which is advantageous for the lightweight design of the secondary battery 100. At the same time, the thinness of the second cover plate 142 is also advantageous for penetration welding between the lower current collector members 130.

[0057] To facilitate welding between the current collector member 130 and the second cover plate 142, selectively referring to Figure 3, in one embodiment of the secondary battery 100 of the present invention, along the axial direction of the secondary battery 100, the current collector member 130 includes a current collector body 131 and a thickened portion 132 that is thicker than the current collector body 131, and the current collector body 131 is electrically connected to the thickened portion 132. The method of the conductive connection may be a welded connection or an integrally molded connection, but is not specifically limited in the present invention. The current collector body 131 is welded to a lower first tab 121 to provide an electrical connection between the electrode assembly 120. The thickened portion 132 protrudes toward the second cover plate 142 side relative to the current collector body 131 and is welded in contact with the surface of the second cover plate 142 facing the electrode assembly 120, forming a first weld mark 1422 between the second cover plate 142 and the current collector member 130. The thickened portion 132 may have a frustoconical structure or a structure with multiple protrusions, but the criterion is that it satisfies the welding strength and flow guidance requirements between it and the second cover plate 142. By installing the thickened portion 132, on the one hand, effective adhesion between the current collector member 130 and the second cover plate 142 is facilitated, thereby ensuring the welding quality between the current collector member 130 and the second cover plate 142. On the other hand, by installing the thickened portion 132, localized thickening of the current collector member 130 can be achieved. Therefore, when laser penetration welding the second cover plate 142 and the current collector member 130 outside the housing 110, the welding difficulty is reduced, the welding process window is improved, the occurrence of burn-through phenomena in the current collector member 130 is reduced, and the welding quality is improved.

[0058] Furthermore, in order to further improve the welding quality between the second cover plate 142 and the current collector 130, as shown in Figure 3, in one embodiment of the secondary battery 100 of the present invention, the thickness of the second cover plate 142 is smaller than the thickness of the thickened portion 132. With this setup, when laser penetration welding is performed on the outside of the housing 110, the welding power can be reduced due to the smaller thickness of the second cover plate 142, thereby contributing to energy saving and emission reduction. At the same time, the reduction in welding power can further reduce the probability of the lower current collector 130 melting through.

[0059] Referring to Figure 5, in one embodiment of the secondary battery 100 of the present invention, the outer diameter of the first cover plate 141 is D1, the inner diameter of the through hole 1411 is D2, and the ratio of D2 to D1 is 0.5 or less. That is, D2 / D1 ≤ 0.5. The specific ratio between D2 and D1 may be 0.1, 0.3, or 0.5, etc. With such an installation, the size of the area in which the through hole 1411 is provided in the first cover plate 141 can be limited, thereby ensuring that the first cover plate 141 has sufficient support strength and support rigidity, and thus the requirements for use of the secondary battery 100 can be met.

[0060] Furthermore, based on the fact that the ratio of the inner diameter D2 of the through hole 1411 to the outer diameter D1 of the first cover plate 141 is 0.5 or less, in one embodiment of the secondary battery 100 of the present invention, the cover plate assembly 140 further includes an explosion-proof notch 143. The explosion-proof notch 143 is installed on the first cover plate 141 as shown in Figures 5 and 8. The explosion-proof notch 143 may be a continuous annular structure or a discontinuous structure. The location of the explosion-proof notch 143 is a region of relatively weak strength in the cover plate assembly 140, and when the internal pressure of the secondary battery 100 exceeds a certain threshold, the explosion-proof notch 143 ruptures, and the internal pressure of the secondary battery 100 is released from the rupture site, thereby preventing a phenomenon in which heat spreads laterally in the secondary battery 100 and causes more serious effects. Preferably, in order to facilitate the positioning of the explosion-proof notch 143 on the first cover plate 141, in this embodiment the explosion-proof notch 143 is an annular structure installed so as to surround the outer circumference of the through hole 1411 and is installed coaxially with the first cover plate 141.

[0061] The explosion-proof notch 143 is installed on the first cover plate 141 under the condition that the ratio of the inner diameter D2 of the through hole 1411 to the outer diameter D1 of the first cover plate 141 is 0.5 or less. This installation reduces the dimensional constraints that the explosion-proof notch 143 faces in the radial direction of the cover plate assembly 140, allowing the explosion-proof notch 143 to have larger design dimensions on the cover plate assembly 140. This allows it to be formed to surround a relatively large explosion-proof valve opening area on the cover plate assembly 140, which is advantageous for improving the explosion-proof decompression capability of the secondary battery 100 and further improves the safety performance of the secondary battery 100. On the other hand, since the ratio of the inner diameter D2 of the through hole 1411 to the outer diameter D1 of the first cover plate 141 is 0.5 or less, this allows the area of ​​the second cover plate 142 located in the through hole 1411 to be limited. As a result, under the condition that the internal pressure of the secondary battery 100 is constant, the pressure on the second cover plate 142 can be reduced accordingly. This reduces the tensile force generated at the third weld mark 1423 at the welding position of the first cover plate 141 and the second cover plate 142, and further reduces the failure of the connection strength between the first cover plate 141 and the second cover plate 142. In this way, the third welded joint 1423 is torn before the explosion-proof notch 143 is opened, allowing the second cover plate 142 to escape as a whole, preventing the problem of abnormal pressure reduction. Furthermore, the pressure applied to the second cover plate 142 is transmitted more effectively to the location of the outer explosion-proof notch 143, making it easier for the explosion-proof notch 143 to rupture smoothly and achieving the expected pressure-reducing explosion-proof effect.

[0062] Referring to Figures 2 and 3, in one embodiment of the secondary battery 100 of the present invention, along the axial direction of the secondary battery 100, on the side of the first tab 121 of the electrode assembly 120, the current collector member 130 is welded in contact with the first tab 121, forming a fourth weld mark 133, and the orthographic projection of the first cover plate 141 covers the fourth weld mark 133. The number and shape trajectory of the fourth weld marks 133 on the current collector member 130 are not limited, as long as they satisfy the connection strength and current guidance requirements between the current collector member 130 and the electrode assembly 120. By the orthographic projection of the first cover plate 141 covering the fourth weld marks 133, the area of ​​the through holes 1411 installed on the first cover plate 141 can be further limited, thereby ensuring that the first cover plate 141 has a sufficient support area, and thereby further ensuring the support strength and rigidity of the first cover plate 141.

[0063] Referring to Figure 12, in one embodiment of the battery pack 200 of the present invention, the battery pack 200 includes a box 210 and at least one secondary battery 100. The box 210 includes a first box section 211 and a second box section 212, the first box section 211 and the second box section 212 covering each other to form a housing space, and the multiple secondary batteries 100 are housed in the housing space, and the multiple secondary batteries 100 can be connected in series and / or in parallel. The battery pack 200 may be, for example, a battery module, a battery pack, etc.

[0064] Referring to Figure 13, in one embodiment of the electronic device 300 of the present invention, the electronic device 300 includes a work unit 310 and a battery pack 200, the work unit 310 being electrically connected to the battery pack 200 to receive support from electrical energy. The work unit 310 may be a unit component that can perform a corresponding task by obtaining electrical energy from the battery pack 200, for example, a fan blade rotation unit, a vacuum cleaner dust collection work unit, an electric vehicle tire drive unit, etc. The electronic device 300 may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, an aerospace vehicle, an electric toy, and a power tool, etc. The vehicle may be a fuel-powered vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or a range extender vehicle, etc. The aerospace vehicle includes airplanes, rockets, space shuttles, and spacecraft, etc. The electric toy includes stationary or mobile electric toys, for example, a game console, an electric vehicle toy, an electric boat toy, and an electric airplane toy, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, and include, for example, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact electric drills, concrete vibrators, and electric planers. Embodiments of the present invention are not particularly limited to the electronic device 300 described above. In one embodiment of the electronic device 300 of the present invention, the electronic device 300 is a vehicle, the work unit 310 is the body of the vehicle, and the battery pack 200 is fixedly mounted on the body and further provides driving force to the vehicle to enable the operation of the vehicle.

[0065] The secondary battery, battery pack, and electronic device provided by the present invention include a cover plate assembly of the secondary battery comprising a first cover plate and a second cover plate, which are installed separately. The first and second cover plates can be individually molded and then fixed together. Compared to an integrated end cover design, such a design allows for an optimized layout of multiple local feature structures on the cover plate assembly by adjusting the connection position relationship between the first and second cover plates, and facilitates the processing and molding of local features. Furthermore, because the first and second cover plates are installed as separate structures, the first and second cover plates can be made of different materials or different thicknesses depending on the actual welding and strength requirements. Therefore, compared to an integrated end cover design, the separate design of the cover plate assembly in the present invention offers superior flexibility and further facilitates structural optimization on the end cover side of the secondary battery. Thus, the present invention effectively overcomes several practical problems in the prior art and has high utility and significance. The embodiments described above are for illustrating the principles and effects of the present invention and are not intended to limit the present invention. Those skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and scope of the invention remain within the scope of the invention. [Industrial applicability]

[0066] The secondary battery, battery pack, and electronic device of the present invention can be applied to the field of battery technology. [Explanation of symbols]

[0067] 100 Secondary battery 110 cabinets 111 Side wall 112 Aperture 113 End wall 120 Electrode Assembly 121 Tab 1 122 Second Tab 130 Current collector 131 Current collector body 132 Thick part 133 Fourth weld mark 140 Cover Plate Assembly 141 First cover plate 1411 Through hole 1412 First protrusion 14121 First recess 1413 Cover section 1414 Second recess 14141 Bottom wall 1415 Second protrusion 1416 No. 6 weld mark 142 Second cover plate 1421 Liquid injection hole 1422 First weld mark 1423 Third weld mark 143 Explosion-proof cutout 150 Sealing plate 160 Butt joint 161 Second weld mark 162 Fifth weld mark 170 Electrode terminal 180 steps 200 Battery Packs 210 boxes 211 First Box Section 212 Second Box Section 300 Electronic equipment 310 Work Unit

Claims

1. A housing comprising a side wall and cover plate assembly having an opening at one end, wherein the cover plate assembly seals the opening, The electrode assembly installed inside the housing, The cover plate assembly includes, A first cover plate, which covers the opening and is sealed to the side wall and includes a through hole, A second cover plate that at least partially blocks the through hole and is connected to the first cover plate, A secondary battery characterized by containing [something].

2. The secondary battery according to claim 1, characterized in that the second cover plate includes an injection hole, the second cover plate is installed between the first cover plate and the electrode assembly, and the second cover plate fits with the inner wall of the through hole to form a step, and the cover plate assembly further includes a sealing plate, the outer edge of the sealing plate fits with the step and is welded to the inner wall of the through hole to seal the injection hole.

3. The secondary battery according to claim 2, further comprising a current collector member electrically connected to the electrode assembly, wherein the current collector member is installed between the electrode assembly and the second cover plate, welded to the second cover plate to form a first weld mark, and the sealing plate covers and seals the first weld mark.

4. The secondary battery according to claim 2, wherein the first cover plate further includes a first protrusion and a cover portion installed so as to surround the outer circumference of the first protrusion, the first protrusion protrudes toward the second cover plate relative to the cover portion, the through hole penetrates the first protrusion, and one side of the first protrusion facing the electrode assembly is welded to the second cover plate.

5. The secondary battery according to claim 4, characterized in that one side of the first protrusion away from the electrode assembly includes a first recess, the sealing plate is welded to the inner wall of the through hole to form a second weld mark, the second weld mark is housed within the first recess, and the top of the second weld mark does not extend beyond the outer surface of the cover portion away from the electrode assembly.

6. The secondary battery according to claim 1, further comprising a current collector, wherein the current collector is installed on one side of the electrode assembly facing the cover plate assembly and is electrically connected to the electrode assembly, the outer edge of the first cover plate is welded to the side wall, at least a portion of the current collector is exposed to the through hole, and at least a portion of the area where the second cover plate blocks the through hole is welded to the current collector.

7. The secondary battery according to claim 6, characterized in that the second cover plate is installed on one side of the first cover plate away from the electrode assembly, and the outer edge of the second cover plate is welded in contact with the first cover plate.

8. The secondary battery according to claim 7, characterized in that the second cover plate is welded to the current collector to form a first weld mark, the first weld mark penetrates the second cover plate and enters the interior of the current collector, but does not exceed the surface of the current collector facing the electrode assembly, and the second cover plate is welded to the first cover plate to form a third weld mark, the third weld mark penetrates the second cover plate and enters the interior of the first cover plate, but does not exceed the surface of the first cover plate facing the electrode assembly.

9. The secondary battery according to claim 7, characterized in that the first cover plate includes a second recess and a cover portion installed so as to surround the outer circumference of the second recess, the second recess is recessed toward the electrode assembly side relative to the cover portion, the second recess includes a bottom wall, the through hole penetrates the bottom wall, the second cover plate is housed in the second recess and welded to the bottom wall.

10. The secondary battery according to claim 6, characterized in that the melting point of the second cover plate is greater than the melting point of the current collector and less than the melting point of the first cover plate.

11. The secondary battery according to claim 10, characterized in that the material of the second cover plate is one of nickel, carbon steel, iron, copper, copper-nickel alloy, or iron-nickel alloy.

12. The secondary battery according to claim 6, characterized in that the thickness of the second cover plate is smaller than the thickness of the first cover plate.

13. The secondary battery according to claim 6, wherein the current collecting member includes a current collecting body and a thicker portion that is thicker than the current collecting body, the thicker portion protrudes toward the second cover plate side relative to the current collecting body, and is welded in contact with the second cover plate.

14. The secondary battery according to claim 13, characterized in that the thickness of the second cover plate is smaller than the thickness of the thickened portion.

15. The secondary battery according to claim 1, characterized in that the ratio of the inner diameter of the through hole to the outer diameter of the first cover plate is 0.5 or less.

16. The secondary battery according to claim 15, further comprising a current collector, wherein the current collector is installed on one side of the electrode assembly facing the cover plate assembly, is electrically connected to the electrode assembly to form a fourth weld mark, and the orthographic projection of the first cover plate along the axial direction of the secondary battery at least partially covers the fourth weld mark.

17. The secondary battery according to claim 15, wherein the cover plate assembly further includes an explosion-proof notch, and the explosion-proof notch is installed on the first cover plate.

18. A battery pack characterized by including a secondary battery as described in any one of claims 1 to 17.

19. An electronic device characterized by including the battery pack described in claim 18.

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