Secondary battery, battery pack and electronic device

Abstract

The invention provides a secondary battery, a battery pack and an electronic device. The secondary battery comprises a shell and an electrode assembly, the shell comprises a side wall with an opening in one end and a cover plate assembly, and the cover plate assembly seals the opening; the electrode assembly is arranged in the shell; wherein the cover plate assembly comprises a first cover plate and a second cover plate, and the first cover plate covers the opening and is in sealed connection with the side wall; the first cover plate comprises a through hole; the second cover plate at least partially shields the through hole; the second cover plate is connected with the first cover plate. According to the invention, the technical problem of poor design flexibility of the end cover of the existing secondary battery can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a secondary battery, a battery pack and an electronic device. Background Art

[0002] Existing secondary batteries are generally provided with end caps at the open ends of the shells to seal the openings. Current end caps are usually of one-piece design, such as one-piece stamping and forming structures. When the end cap is matched with other components, it is often necessary to make a variety of structural features on the local area of ​​the end cap, such as local depressions, local grooves, holes, etc., to meet the corresponding matching and installation requirements. However, due to the limitations of molding technology and processing costs, the one-piece end cap often has problems such as difficulty in one-time molding and poor molding accuracy when molding multiple different structural features, resulting in poor flexibility in the design of the end cap and limiting the structural optimization of the end cap side. Summary of the Invention

[0003] The present invention provides a secondary battery, a battery pack and an electronic device to improve the technical problem of poor flexibility in the design of the end cap of the existing secondary battery.

[0004] To achieve the above-mentioned objectives and other related objectives, the present invention provides a secondary battery, which comprises: a shell and an electrode assembly; the shell comprises a side wall with an opening at one end and a cover assembly, the cover assembly sealing the opening; the electrode assembly is arranged in the shell; wherein the cover assembly comprises: a first cover and a second cover, the first cover covers the opening and is sealed with the side wall; the first cover comprises a through hole; the second cover at least partially blocks the through hole; and the second cover is connected to the first cover.

[0005] In one example of a secondary battery of the present invention, the second cover plate includes a liquid injection hole, the second cover plate is arranged between the first cover plate and the electrode assembly, and the second cover plate and the inner wall of the through hole cooperate to form a step, and the cover plate assembly also includes a sealing plate; the outer peripheral edge of the sealing plate cooperates with the step and is welded to the inner wall of the through hole to seal the liquid injection hole.

[0006] In an example of the secondary battery of the present invention, the secondary battery further includes a current collecting component electrically connected to the electrode assembly, the current collecting component is arranged between the electrode assembly and the second cover plate, and is welded to the second cover plate to form a first weld mark, and the sealing plate covers the first weld mark.

[0007] In an example of the secondary battery of the present invention, the first cover plate also includes a first protrusion and a cover body portion arranged around the outer periphery of the first protrusion, the first protrusion protrudes toward the second cover plate relative to the cover body portion, the through hole passes through the first protrusion, and the side of the first protrusion facing the electrode assembly is welded to the second cover plate.

[0008] In an example of a secondary battery of the present invention, the side of the first convex portion facing away from the electrode assembly includes a first concave portion, and the sealing plate is welded to the inner wall of the through hole to form a second weld mark, the second weld mark is accommodated in the first concave portion, and the top of the second weld mark does not exceed the outer surface of the cover body facing away from the electrode assembly.

[0009] In an example of a secondary battery of the present invention, the secondary battery further includes a current collecting component, which is arranged on the side of the electrode assembly facing the cover plate assembly and is electrically connected to the electrode assembly; the outer periphery of the first cover plate is welded to the side wall, at least a portion of the current collecting component is exposed to the through hole, and the area of ​​the second cover plate that blocks the through hole is at least partially welded to the current collecting component.

[0010] In an example of the secondary battery of the present invention, the second cover plate is disposed on a side of the first cover plate away from the electrode assembly, and an outer edge of the second cover plate abuts against and is welded to the first cover plate.

[0011] In an example of a secondary battery of the present invention, the second cover plate is welded to the current collecting member to form a first weld mark, which penetrates the second cover plate into the interior of the current collecting member and does not exceed the surface of the current collecting member facing the electrode assembly; the second cover plate is welded to the first cover plate to form a third weld mark, which penetrates the second cover plate into the interior of the first cover plate and does not exceed the surface of the first cover plate facing the electrode assembly.

[0012] In an example of a secondary battery of the present invention, the first cover plate includes a second recess and a cover body portion arranged around the outer periphery of the second recess, the second recess is recessed toward the electrode assembly side relative to the cover body portion, the second recess includes a bottom wall, a through hole passes through the bottom wall, the second cover plate is accommodated in the second recess, and is welded to the bottom wall.

[0013] In an example of the secondary battery of the present invention, the melting point of the second cap plate is greater than the melting point of the current collecting member and is lower than the melting point of the first cap plate.

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

[0015] In an example of the secondary battery of the present invention, the thickness of the second cover plate is smaller than the thickness of the first cover plate.

[0016] In an example of the secondary battery of the present invention, along the axial direction of the secondary battery, the current collecting component includes a current collecting body and a thickened portion with a thickness greater than that of the current collecting body. The thickened portion protrudes toward the second cover plate relative to the current collecting body and abuts and welds with the second cover plate.

[0017] In an example of the secondary battery of the present invention, the thickness of the second cover plate is smaller than the thickness of the thickened portion.

[0018] In an example of the secondary battery of the present invention, a ratio of an inner diameter of the through hole to an outer diameter of the first cover plate is less than or equal to 0.5.

[0019] In an example of a secondary battery of the present invention, the secondary battery further includes a current collecting member, which is arranged on the side of the electrode assembly facing the cover plate assembly and is electrically connected to the electrode assembly to form a fourth weld mark; along the axial direction of the secondary battery, the orthographic projection of the first cover plate at least partially covers the fourth weld mark.

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

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

[0022] The present invention further provides an electronic device, which includes the battery pack.

[0023] The secondary battery, battery pack and electronic device provided by the present invention, the cover plate assembly of the secondary battery includes a first cover plate and a second cover plate that are separately arranged, and the first cover plate and the second cover plate can be formed separately and then fixed together. Compared with the one-piece end cover design, such a design can not only achieve the optimized layout of multiple local feature structures on the cover plate assembly by adjusting the connection position relationship between the first cover plate and the second cover plate, so as to facilitate the processing and forming of local features; but also because the first cover plate and the second cover plate are arranged as split structures, the first cover plate and the second cover plate can also use different materials or different material thicknesses according to actual welding requirements and strength requirements. Therefore, compared with the one-piece end cover design, the split design of the cover plate assembly in the present invention is more flexible and more convenient for the structural optimization of the secondary battery on the end cover side. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 A cross-sectional view of the overall structure of an embodiment of a secondary battery of the present invention;

[0026] Figure 2 for Figure 1 A local enlarged view of the middle area A;

[0027] Figure 3 This is a partial enlarged view of the installation positions of the first cover plate and the second cover plate in an embodiment of the secondary battery of the present invention;

[0028] Figure 4This is a schematic diagram of the three-dimensional structure of the first cover plate in an embodiment of a secondary battery of the present invention;

[0029] Figure 5 A partial cross-sectional view of a first cover plate in an embodiment of a secondary battery of the present invention;

[0030] Figure 6 A schematic diagram of a cover plate assembly in an embodiment of a secondary battery of the present invention;

[0031] Figure 7 A cross-sectional view of a cover plate assembly in an embodiment of a secondary battery of the present invention;

[0032] Figure 8 This is a schematic diagram of the installation positions of the first cover plate and the second cover plate in an embodiment of a secondary battery of the present invention;

[0033] Figure 9 This is a schematic diagram of the welding position of the first cover plate and the second cover plate in another embodiment of the secondary battery of the present invention;

[0034] Figure 10 Schematic diagram of the structure of the thickened portion and the second cover plate in one embodiment of the secondary battery of the present invention;

[0035] Figure 11 This is a partial enlarged view of the installation position of the thickened portion and the second cover plate in an embodiment of the secondary battery of the present invention;

[0036] Figure 12 This is a schematic diagram of the overall structure of a battery pack according to an embodiment of the present invention;

[0037] Figure 13 This is a schematic structural diagram of the battery pack of the present invention installed on a vehicle.

[0038] Component number description

[0039] 100, secondary battery; 110, housing; 111, side wall; 112, opening; 113, end wall; 120, electrode assembly; 121, first electrode tab; 122, second electrode tab; 130, current collecting member; 131, current collecting body; 132, thickened portion; 133, fourth weld mark; 140, cover assembly; 141, first cover; 1411, through hole; 1412, first protrusion; 14121, first recess; 1413, cover body; 1414, second recess; 14141, bottom Wall; 1415, second protrusion; 1416, sixth weld mark; 142, second cover plate; 1421, liquid injection hole; 1422, first weld mark; 1423, third weld mark; 143, explosion-proof notch; 150, sealing plate; 160, butt joint; 161, second weld mark; 162, fifth weld mark; 170, electrode terminal; 180, stage; 200, battery pack; 210, box; 211, first box part; 212, second box part; 300, electronic device; 310, working part. DETAILED DESCRIPTION

[0040] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following examples and the features in the examples can be combined with each other unless they conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific embodiments, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0041] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those described in the examples of the present invention may also be used to implement the present invention.

[0042] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0043] See also 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 is fixedly connected to the first cover plate 141, thereby enabling the cover plate assembly 140 to achieve a split design. Compared with an integrated end cap design, such a design can improve the design flexibility of the cover plate assembly 140.

[0044] 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, etc., and the embodiments of the present invention are not limited to this. The secondary battery 100 may be cylindrical, flat, rectangular, or other shapes, and the embodiments of the present invention are not limited to this.

[0045] See also Figure 1 and Figure 2 , further describing the structure of the secondary battery 100 , the secondary battery 100 includes: a housing 110 and an electrode assembly 120 .

[0046] An installation cavity is formed in the shell 110 for installing the electrode assembly 120, the electrolyte (not shown) and other components. Specifically, the size of the shell 110 can be determined according to the specific size of the electrode assembly 120, such as a diameter of 46 mm, a height of 80 mm, 95 mm, 120 mm and other specifications. The shell 110 can be in a variety of shapes, such as cylindrical, prismatic, etc. The material of the shell 110 can also be a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the shell 110 from rusting during long-term use, a layer of rust-proof material, such as metal nickel, etc., can also be plated on the surface of the shell 110.

[0047] See also Figure 1 and Figure 2 In one embodiment of the secondary battery 100 of the present invention, the housing 110 is cylindrical and includes an end wall 113, a side wall 111 surrounding the end wall 113, and a cover assembly 140. Along the height of the housing 110, one end of the side wall 111 is fixedly connected to the end wall 113, forming a closed end. The other end of the side wall 111 is provided with an opening 112. The cover assembly 140 is disposed at the opening 112 and seals the opening 112.

[0048] like Figure 1 and Figure 2As shown, the electrode assembly 120 is housed in the shell 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 provided 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 collector and a positive electrode active material layer, and the positive electrode active material layer is coated on the surface of the positive electrode collector; the positive electrode collector includes a positive electrode coating area and a positive electrode tab connected to the positive electrode coating area, the positive electrode coating area is coated with a positive electrode active material layer, and the positive electrode tab is not coated with a positive electrode active material layer. The negative electrode sheet includes a negative current collector and a negative active material layer, which is coated on the surface of the current collector. The negative current collector includes a negative coating region and a negative tab connected to the negative coating region. The negative coating region is coated with the negative active material layer, while the negative tab is uncoated. For lithium-ion batteries, for example, the positive current collector can be made of aluminum, and the positive active material layer includes a positive active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative current collector can be made of copper, and the negative active material layer includes a negative active material, which can be carbon or silicon. The separator can be primarily made of PP or PE. To protect and insulate the electrode assembly 120, an insulating film can be applied to the outside of the electrode assembly 120. The insulating film can be made of PP, PE, PET, PVC, or other polymer materials.

[0049] Please continue reading Figure 1 and Figure 2 In one example of the secondary battery 100 of the present invention, the electrode assembly 120 is sealed and mounted within the housing 110. The electrode assembly 120 is provided with a first electrode tab 121 and a second electrode tab 122 at either end of the secondary battery 100 in the height direction. The first electrode tab 121 and the second electrode tab 122 have opposite polarities. The first electrode tab 121 faces the opening 112 of the housing 110 and is the negative electrode tab. It should be noted that in other embodiments, the first electrode tab 121 may be the positive electrode tab, and the second electrode tab 122 may be the negative electrode tab.

[0050] See also Figure 1In one example of the secondary battery 100 of the present invention, a terminal mounting hole is formed through the end wall 113 of the housing 110. The electrode terminal 170 is installed in a sealed and insulated manner within the terminal mounting hole. The mounting method of the electrode terminal 170 on the end wall 113 is not limited as long as the seal and insulation between the electrode terminal 170 and the end wall 113 are achieved. The electrode assembly 120 has a second electrode tab 122 on the side facing the end wall 113. One end of the electrode terminal 170 can be directly welded to the second electrode tab 122 or conductively connected to the second electrode tab 122 via a current collecting member, without specific limitations.

[0051] See also Figure 1 and Figure 2 In one example of the secondary battery 100 of the present invention, the current collecting member 130 is disposed within the housing 110 and is located on the side of the electrode assembly 120 facing the cap plate assembly 140. The current collecting member 130 is welded to the first electrode tab 121 and the housing 110 to achieve electrical connection. The current collecting member 130 can be welded to the cap plate assembly 140, to the sidewall 111, or to both the cap plate assembly 140 and the sidewall 111. The specific location and area of ​​the welding between the current collecting member 130 and the first electrode tab 121 are not limited, as long as a stable electrical connection between the current collecting member 130 and the first electrode tab 121 is achieved.

[0052] It should be noted that in some other embodiments, the current collecting component 130 may not be arranged between the cover plate assembly 140 and the electrode assembly 120. The cover plate assembly 140 is directly welded to the first electrode tab 121 on the electrode assembly 120 and is simultaneously welded to the side wall 111, thereby realizing the electrical connection between the electrode assembly 120 and the shell 110.

[0053] See also 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 shell 110. There can be various sealing connection methods, such as welding sealing, mechanical crimping sealing, etc. The first cover plate 141 includes a through hole 1411, and the through hole 1411 can be located in the central area of ​​the first cover plate 141, or it can be offset from the central area. The through hole 1411 can also have various shapes, such as square holes, round holes or other special-shaped holes. Preferably, in order to facilitate the processing and positioning of the through hole 1411 on the first cover plate 141, in this embodiment, the through hole 1411 is a circular hole structure, and the through hole 1411 is coaxially arranged with the first cover plate 141.

[0054] See also Figure 3 、 Figure 6 and Figure 7The second cover plate 142 is disposed on a side of the current collecting member 130 facing away from the electrode assembly 120, and the second cover plate 142 at least partially blocks the through hole 1411. The second cover plate 142 is connected to the first cover plate 141 by welding, riveting, or any other method that can achieve electrical connection between the first cover plate 141 and the second cover plate 142.

[0055] See also Figure 2 、 Figure 6 and Figure 7 Preferably, in this embodiment, the first cover plate 141 and the second cover plate 142 are welded together. The second cover plate 142 can be in the shape of a disk that matches the through hole 1411, or can be in other shapes that can at least partially block the through hole 1411, such as a rectangular plate, a polygonal plate, etc. Preferably, in this embodiment, the second cover plate 142 is a substantially disk-shaped structure and is coaxially arranged with the through hole 1411. This facilitates the positioning and installation between the second cover plate 142 and the first cover plate 141, and helps improve the assembly efficiency between the second cover plate 142 and the first cover plate 141.

[0056] The installation 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 can be installed on the side of the first cover plate 141 away from the electrode assembly 120 to form a accommodating cavity feature on the cover plate assembly 140 that is open toward the side of the electrode assembly 120, so that part of the current collecting component 130 can be accommodated in the axial direction, which is convenient for welding between the current collecting component 130 and the second cover plate 142; the second cover plate 142 can also be installed on the side of the first cover plate 141 facing the electrode assembly 120 to form a step feature on the cover plate assembly 140 facing the outside of the cover plate assembly 140, so that it is convenient to form a mating positioning relationship with the 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 to be different based on the welding requirements and connection strength at their respective locations. For example, when the second cover plate 142 needs to be welded to the first cover plate 141 and the current collecting member 130 simultaneously, the second cover plate 142 can be made of a material with a melting point between the first cover plate 141 and the current collecting member 130. This ensures the welding quality between the first cover plate 141 and the second cover plate 142, while also ensuring the welding quality between the second cover plate 142 and the current collecting member 130. The thickness of the first cover plate 141 and the second cover plate 142 can be designed to be different to meet the different strength and welding requirements at their respective connection locations. For example, because the first cover plate 141 needs to withstand greater strength and pressure, it needs to be thicker. However, when the second cover plate 142 needs to be welded to the current collecting member 130 below, it can be thinner to facilitate penetration welding.

[0057] Since the cover plate assembly 140 in this embodiment includes a first cover plate 141 and a second cover plate 142 that are separately arranged, the first cover plate 141 and the second cover plate 142 can be formed separately and then fixed together. Compared with the one-piece end cap design, such a design can not only achieve the 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 to facilitate the processing and forming of local features; but also because the first cover plate 141 and the second cover plate 142 are separated structures, the first cover plate 141 and the second cover plate 142 can also use different materials or different material thicknesses according to actual welding requirements and strength requirements. Therefore, compared with the one-piece end cap design, the split design of the cover plate assembly 140 in this embodiment has better flexibility and is more convenient for structural optimization of the secondary battery 100 on the end cap side.

[0058] See also Figure 2 、 Figure 3 and Figure 7 In an example of the secondary battery 100 of the present invention, the second cover plate 142 includes a liquid injection hole 1421. The liquid injection hole 1421 can be located in the central area of ​​the second cover plate 142, or in an area off-center of the second cover plate 142, so as to meet the liquid injection requirements of the electrode assembly 120. The secondary battery 100 also includes a sealing plate 150. The sealing plate 150 is arranged on the side of the second cover plate 142 away from the current collecting member 130, and the sealing plate 150 covers the liquid injection hole 1421. Along the axial direction of the secondary battery 100, the second cover plate 142 is arranged between the first cover plate 141 and the current collecting member 130, and the outer peripheral edge of the second cover plate 142 abuts against the outer edge of the through hole 1411 on the side facing the electrode assembly 120, so that the second cover plate 142 cooperates with the inner wall of the through hole 1411 to form a stage 180, as shown Figure 7 As shown, the outer periphery of the sealing plate 150 is accommodated within the stage 180 and cooperates with the stage 180. The outer periphery of the sealing plate 150 abuts against the inner wall of the through hole 1411 to form a butt joint 160 circumferentially arranged around the through hole 1411. A second weld mark 161 is formed at the location 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 to achieve a seal on the injection hole 1421. Since the platform stage 180 can be formed by the positional coordination between the second cover plate 142 and the through hole 1411, the sealing plate 150 can be installed in the platform stage 180, thereby realizing the coordinated installation of the sealing plate 150 on the cover plate assembly 140. Therefore, there is no need to integrally stamp and form the platform stage 180 on the first cover plate 141 or the second cover plate 142. Therefore, the forming accuracy of the platform stage 180 can be improved, and then the coordination accuracy between the sealing plate 150 and the platform stage 180 can be improved, and finally the welding quality between the sealing plate 150 and the platform stage 180 can be improved, thereby ensuring the sealing performance of the sealing plate 150 to the injection hole 1421.

[0059] Further, see Figure 2 and Figure 3 In one example of the secondary battery 100 of the present invention, the orthographic projection of the current collecting member 130 is at least partially located 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 collecting member 130 is at least partially welded to the underlying current collecting member 130, forming a first weld mark 1422. The sealing plate 150, located on the side of the second cover plate 142 facing away from the electrode assembly 120, seals the first weld mark 1422. This arrangement allows the sealing plate 150 to seal the first weld mark 1422 while simultaneously sealing the injection hole 1421. This reduces the probability of rust at the first weld mark 1422 and ensures the stability of the electrical connection between the current collecting member 130 and the second cover plate 142.

[0060] See also Figures 3 to 5 In one example 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. The cover portion 1413 is disposed around the outer periphery of the first protrusion 1412. Along the axial direction of the secondary battery 100, the first protrusion 1412 protrudes toward the second cover plate 142 relative to the cover portion 1413. The first protrusion 1412 can be located in the center region of the first cover plate 141 or in an edge region of the first cover plate 141. Preferably, in this embodiment, the first protrusion 1412 is located in the center region of the first cover plate 141, which facilitates positioning and processing of the first protrusion 1412 on the first cover plate 141. The through hole 1411 extends through the first protrusion 1412 along the axial direction of the secondary battery 100. The through hole 1411 can be coaxial with the first protrusion 1412, or they can be non-coaxial. Preferably, in this embodiment, the through hole 1411 is coaxial with the first protrusion 1412, which facilitates the positioning of the through hole 1411 on the first cover plate 141. The side of the first protrusion 1412 facing the electrode assembly 120 abuts and welds with the surface of the second cover plate 142 facing away from the electrode assembly 120. By providing the first protrusion 1412 and abutting and welding the edge area of ​​the first protrusion 1412 with the second cover plate 142, localized contact between the first cover plate 141 and the second cover plate 142 is achieved, increasing the effective contact area between the first cover plate 141 and the second cover plate 142 at the edge of the through hole 1411, thereby improving the welding quality of the first cover plate 141 and the second cover plate 142 at this location.

[0061] See also Figure 3In one example of the secondary battery 100 of the present invention, along the axial direction of the secondary battery 100, the side of the first protrusion 1412 facing away from the electrode assembly 120 includes a first recess 14121. The first recess 14121 surrounds the outer periphery of the through-hole 1411. A second weld mark 161, formed by welding the outer periphery of the sealing plate 150 to the inner wall of the through-hole 1411, is located within the first recess 14121. The top of the second weld mark 161 does not extend beyond the outer surface of the cover 1413 facing away from the electrode assembly 120. By locating 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 1413 is reduced. This not only ensures the flatness of the outer end surface of the cover assembly 140, facilitating the welding of other conductive components thereto, but also better protects the second weld mark 161, reducing the probability of it being damaged by impact. In addition, since the first concave portion 14121 is disposed on the side of the first convex portion 1412 facing away from the electrode assembly 120 , the first convex portion 1412 and the first concave portion 14121 can be conveniently stamped at one time, which helps to reduce processing costs.

[0062] See also Figure 7 and Figure 8 In an example of the secondary battery 100 of the present invention, the outer edge of the first cover plate 141 includes a second protrusion 1415 that matches the opening 112, and the second protrusion 1415 is arranged around the outer periphery of the cover body 1413. The second protrusion 1415 protrudes toward the electrode assembly 120. Along the radial direction of the secondary battery 100, the side wall of the second protrusion 1415 away from the cover body 1413 is welded to the inner surface of the side wall 111. Along the axial direction of the secondary battery 100, the surface of the second protrusion 1415 facing the electrode assembly 120 is in contact with and welded to the current collecting member 130, forming a structure as shown in FIG. Figure 8 The sixth weld mark 1416 is shown to achieve electrical connection between the current collecting member 130 and the cap plate assembly 140. By providing the second protrusion 1415 and welding the second protrusion 1415 to the current collecting member 130, the welding position between the current collecting member 130 and the cap plate assembly 140 can be positioned away from the injection hole 1421 in the radial direction of the secondary battery 100. This can reduce the probability of welding slag on the surface of the current collecting member 130 entering the interior of the electrode assembly 120 with the electrolyte during the injection process, thereby ensuring normal circulation of the electrolyte within the electrode assembly 120.

[0063] See also Figure 3 In an example of the secondary battery 100 of the present invention, along the axial direction of the secondary battery 100, at least a portion of the current collecting member 130 is exposed to the through hole 1411, and the area of ​​the second cover plate 142 that blocks the through hole 1411 is at least partially welded to the current collecting member 130 to form a Figure 3The first weld mark 1422 is shown in FIG. The number and shape of the first weld mark 1422 are not limited, as long as the first weld mark 1422 is located within the through hole 1411 and the welding head can perform penetration welding on the side of the second cover plate 142 facing away from the electrode assembly 120. By welding the second cover plate 142 to the current collecting member 130, the penetration welding process between the second cover plate 142 and the current collecting member 130 can be optimized by controlling the thickness of the second cover plate 142. In this way, during the welding process, the quality of the first weld mark 1422 can be guaranteed, and the probability of the current collecting member 130 being welded through can be reduced. At the same time, since the second cover plate 142 and the first cover plate 141 are separated, changes in the thickness of the second cover plate 142 will not affect the thickness of the first cover plate 141, thereby ensuring the compressive strength and supporting strength of the first cover plate 141.

[0064] See also Figures 9 to 11 In one example of the secondary battery 100 of the present invention, the second cover plate 142 is disposed on the side of the first cover plate 141 facing away from the electrode assembly 120 along the axial direction of the secondary battery 100. The second cover plate 142 at least partially obstructs the through-hole 1411. The outer edge of the second cover plate 142 abuts and is welded to the surface of the first cover plate 141 facing 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 collecting member 130 may be welded to the underlying current collecting member 130. In other embodiments, the side of the second cover plate 142 facing the current collecting member 130 may not be welded to the underlying current collecting member 130. This arrangement allows welding of the first and second cover plates 141 and 142 to be performed on the outside of the first cover plate 141, thereby reducing the probability of foreign matter such as welding slag generated in the welding area entering the interior of the electrode assembly 120 and further facilitating a clean environment within the electrode assembly 120. At the same time, when the central area of ​​the second cover plate 142 is welded to the current collecting member 130 below, welding is also performed on the outside of the electrode assembly 120, which also reduces the probability of foreign matter such as welding slag generated during the welding process at this position entering the interior of the electrode assembly 120.

[0065] For further information, please refer to Figures 9 to 11 In an example of the secondary battery 100 of the present invention, along the axial direction of the secondary battery 100, on the side of the second cover plate 142 facing away from the electrode assembly 120, the second cover plate 142 and the current collecting member 130 are penetrated and welded to form a first weld mark 1422. The first weld mark 1422 penetrates the second cover plate 142 and enters the interior of the current collecting member 130 without exceeding the surface of the current collecting member 130 facing the electrode assembly 120. That is, the first weld mark 1422 does not penetrate the current collecting member 130. Figure 11On the side of the second cover plate 142 facing away from the electrode assembly 120, the second cover plate 142 and the first cover plate 141 are penetrated and welded to form a third weld mark 1423. The third weld mark 1423 penetrates the second cover plate 142 and enters the interior of the first cover plate 141 without exceeding the surface of the first cover plate 141 facing the electrode assembly 120. That is, the third weld mark 1423 does not penetrate the first cover plate 141. Figure 11 This arrangement can better ensure that the first weld mark 1422 does not penetrate the current collecting member 130 and the third weld mark 1423 does not penetrate the first cover plate 141, thereby further reducing the probability of foreign matter such as welding slag generated during the welding process between the second cover plate 142 and the current collecting member 130, and between the second cover plate 142 and the first cover plate 141, entering the interior of the electrode assembly 120, thereby better ensuring the service life of the secondary battery 100.

[0066] In order to reduce the installation size occupied by the second cover plate 142 in the height direction of the secondary battery 100, please refer to Figure 11 In an example 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 is arranged around the outer periphery of the second recess 1414, and the second recess 1414 is recessed toward the electrode assembly 120 relative to the cover portion 1413. The second recess 1414 can have a variety of shapes, such as a rectangular parallelepiped and a cylindrical shape. To facilitate positioning and molding, in this embodiment, the second recess 1414 is a cylindrical structure and is coaxially arranged relative to the cover portion 1413. The second recess 1414 includes a bottom wall 14141, and the through hole 1411 extends through the bottom wall 14141. Through hole 1411 can be provided in the center region of bottom wall 14141 or in the edge region of bottom wall 14141. Preferably, to facilitate the molding process of through hole 1411 on bottom wall 14141, in this embodiment, through hole 1411 is provided in the center region of bottom wall 14141 and is coaxial with second recess 1414. Second cover plate 142 is accommodated in second recess 1414. In the depth direction of second recess 1414, second cover plate 142 can be completely or partially accommodated within second recess 1414, without limitation. The outer edge of second cover plate 142 abuts and is welded to the outer edge of bottom wall 14141 to form third weld mark 1423. By providing the second recess 1414 and accommodating the second cover plate 142 in the second recess 1414 , the height space of the secondary battery 100 occupied by the second cover plate 142 when installed on the first cover plate 141 can be reduced, which is beneficial to improving the volume energy density of the secondary battery 100 .

[0067] In order to further reduce the height of the secondary battery 100, please continue to refer to Figure 11In an example of the secondary battery 100 of the present invention, the sealing plate 150 is arranged on the side of the second cover plate 142 facing away from the electrode assembly 120 and is accommodated in the second recess 1414. The outer peripheral surface of the sealing plate 150 cooperates with the side wall of the second recess 1414, and the end surface of the sealing plate 150 facing the electrode assembly 120 is at least partially abutted and welded to the second cover plate 142 to form 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, thereby reducing the probability of rust at the first weld mark 1422 and the third weld mark 1423 and ensuring the stability of the welding quality. It should be noted that when the second cover plate 142 is provided with an injection hole 1421, the sealing plate 150 can also seal the injection hole 1421.

[0068] Considering that in a secondary battery, the current collecting member 130 is primarily used for current conduction, it needs to have good flow conduction performance and chemical corrosion resistance. Since the cover plate needs to be welded to the side wall 111 and forms part of the housing 110, it needs to have high strength and good rust resistance. In view of this, the current collecting member 130 and the cover plate are generally not made of the same material. The current collecting member 130 is generally made of copper, nickel, aluminum, etc., while the cover plate is generally made of stainless steel. This can cause problems such as difficulty in welding the current collecting member 130 and the cover plate, and difficulty in ensuring welding quality. Please refer to Figure 3 In one example of the secondary battery 100 of the present invention, the melting point of the second cover plate 142 is greater than that of the current collecting member 130, but less than that of the first cover plate 141. By setting the melting point of the second cover plate 142 to be greater than that of the current collecting member 130, but less than that of the first cover plate 141, the melting point of the second cover plate 142 can be positioned between the melting points of the first cover plate 141 and the current collecting member 130. This reduces the melting point difference between the second cover plate 142 and the first cover plate 141, ensuring weld quality. Furthermore, the melting point difference between the second cover plate 142 and the current collecting member 130 is reduced, ensuring weld quality between the second cover plate 142 and the first cover plate 141. This effectively resolves the difficulty and difficulty in ensuring weld quality between the current collecting member 130 and the cover plate.

[0069] Considering the common material properties of the first cover plate 141 and the current collecting member 130, in one embodiment of the secondary battery 100 of the present invention, the second cover plate 142 is preferably made of any one of nickel, carbon steel, iron, copper, a copper-nickel alloy, or an iron-nickel alloy. These materials not only ensure that the melting point of the second cover plate 142 is between the melting points of the first cover plate 141 and the current collecting member 130, but also ensure that the second cover plate 142 has excellent electrical conductivity and corrosion resistance.

[0070] In an example of the secondary battery 100 of the present invention, the thickness of the second cover plate 142 is less than the thickness of the first cover plate 141. The thickness of the first cover plate 141 and the second cover plate 142 will affect the strength of the cover plate assembly 140 at different positions. Figure 3 As shown, due to the different placement of the first cover plate 141 and the second cover plate 142, the strength and rigidity requirements for 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. When the secondary battery 100 expands and deforms, it will be subjected to significant pressure. Therefore, the first cover plate 141 needs to have greater support strength and rigidity to suppress deformation of the secondary battery 100. Therefore, the thickness of the first cover plate 141 is also larger. The second cover plate 142 is located in the center area of ​​the first cover plate 141. Therefore, when the secondary battery 100 expands and deforms, it deforms less than the first cover plate 141. Therefore, the second cover plate 142 can have a smaller thickness. This arrangement ensures that the first cover plate 141 and the second cover plate 142 meet their respective strength requirements while reducing the weight of the second cover plate 142, thereby facilitating the lightweight design of the secondary battery 100. At the same time, since the second cover plate 142 is thinner, it is more conducive to penetration welding with the current collecting member 130 below.

[0071] In order to facilitate welding between the current collecting member 130 and the second cover plate 142, optionally, refer to Figure 3 In one example of a secondary battery 100 according to the present invention, along the axial direction of the secondary battery 100, the current collecting member 130 includes a current collecting body 131 and a thickened portion 132 having a thickness greater than that of the current collecting body 131. The current collecting body 131 and the thickened portion 132 are electrically connected, either by welding or integral molding, without specific limitation. The current collecting body 131 is welded to the underlying first electrode tab 121 to achieve electrical connection with the electrode assembly 120. The thickened portion 132 protrudes relative to the current collecting body 131 toward the second cover plate 142 and abuts and welds to 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 collecting member 130. The thickened portion 132 can have a truncated cone structure or a plurality of protruding bumps, depending on whether the structure satisfies the welding strength and current conduction requirements with the second cover plate 142. By providing the thickened portion 132, on the one hand, the effective fitting between the current collecting component 130 and the second cover plate 142 can be facilitated, thereby ensuring the welding quality between the current collecting component 130 and the second cover plate 142; on the other hand, the provision of the thickened portion 132 can achieve local thickening of the current collecting component 130. When the second cover plate 142 and the current collecting component 130 are laser-penetrated and welded outside the shell 110, the welding difficulty can be reduced, the welding process window can be improved, the phenomenon of welding through of the current collecting component 130 can be reduced, and the welding quality can be improved.

[0072] Furthermore, in order to further improve the welding quality between the second cover plate 142 and the current collecting member 130, as shown in FIG. Figure 3 As shown, in one example of the secondary battery 100 of the present invention, the thickness of the second cover plate 142 is less than that of the thickened portion 132. This arrangement allows for reduced welding power during laser penetration welding of the second cover plate 142 and the current collecting member 130 outside the housing 110 due to the lower thickness of the second cover plate 142, thereby contributing to energy conservation and emission reduction. Furthermore, this reduced welding power further reduces the probability of welding through the lower current collecting member 130.

[0073] See also Figure 5 In one example 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 less than or equal to 0.5, that is, D2 / D1 ≤ 0.5. The specific ratio between D2 and D1 can be 0.1, 0.3, or 0.5. This configuration limits the area of ​​the through hole 1411 in the first cover plate 141, thereby ensuring that the first cover plate 141 has sufficient support strength and rigidity to meet the operating requirements of the secondary battery 100.

[0074] Furthermore, on the basis 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 less than or equal to 0.5, further, in an example of the secondary battery 100 of the present invention, the cover plate assembly 140 further includes an explosion-proof notch 143, and the explosion-proof notch 143 is provided on the first cover plate 141, such as Figure 5 and Figure 8 As shown. The explosion-proof notch 143 can be a continuous annular structure or a discontinuous structure. The explosion-proof notch 143 is located in an area where the strength of the cover assembly 140 is relatively weak. When the air pressure inside the secondary battery 100 exceeds a certain threshold, the explosion-proof notch 143 will rupture, and the air pressure inside the secondary battery 100 will be discharged from the rupture, thereby preventing the secondary battery 100 from experiencing lateral heat spread and causing more serious consequences. Preferably, in order to facilitate the positioning processing of the explosion-proof notch 143 on the first cover 141, in this embodiment, the explosion-proof notch 143 is a circular ring structure arranged around the outer periphery of the through hole 1411, and is coaxially arranged with the first cover 141.

[0075] By setting the explosion-proof notch 143 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 less than or equal to 0.5, such a setting can, on the one hand, reduce the size restriction of the explosion-proof notch 143 in the radial direction of the cover plate assembly 140, so that the explosion-proof notch 143 can obtain a larger design size on the cover plate assembly 140, thereby being able to form a larger explosion-proof valve opening area on the cover plate assembly 140, which is beneficial to improving the explosion-proof pressure relief capability of the secondary battery 100, and further improving 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 less than or equal to 0.5, the area of ​​the second cover plate 142 located at the through hole 1411 can be limited. Therefore, under the condition of a certain internal pressure of the secondary battery 100, the pressure on the second cover plate 142 will be correspondingly reduced, thereby reducing the pulling force generated by the third weld mark 1423 at the welding position between the first cover plate 141 and the second cover plate 142, thereby reducing the damage to the connection strength between the first cover plate 141 and the second cover plate 142, and preventing the third weld mark 1423 from being torn before the explosion-proof notch 143 is opened, thereby preventing the second cover plate 142 from being completely dislodged and causing abnormal pressure relief. In addition, the pressure on the second cover plate 142 can be better transmitted to the outer explosion-proof notch 143, thereby facilitating the smooth rupture of the explosion-proof notch 143 and achieving the desired pressure relief and explosion-proof effect.

[0076] See also Figure 2 and Figure 3 In one example of the secondary battery 100 of the present invention, along the axial direction of the secondary battery 100, on the side of the first electrode tab 121 of the electrode assembly 120, the current collecting member 130 is welded to the first electrode tab 121, forming a fourth weld mark 133. The orthographic projection of the first cover plate 141 covers the fourth weld mark 133. The number and shape of the fourth weld marks 133 on the current collecting member 130 are not limited, as long as they meet the connection strength and current conduction requirements between the current collecting member 130 and the electrode assembly 120. By ensuring that the orthographic projection of the first cover plate 141 covers the fourth weld marks 133, the area of ​​the through-holes 1411 provided in the first cover plate 141 can be further limited, ensuring that the first cover plate 141 has sufficient support area, thereby further enhancing the support strength and rigidity of the first cover plate 141.

[0077] See also Figure 12In one embodiment of a battery pack 200 of the present invention, the battery pack 200 includes a housing 210 and at least one secondary battery 100. The housing 210 includes a first housing portion 211 and a second housing portion 212. The first housing portion 211 and the second housing portion 212 overlap to form a storage space. Multiple secondary batteries 100 are housed within the storage space. The multiple secondary batteries 100 can be connected in series and / or in parallel. The battery pack 200 can be, for example, a battery module, a battery pack, or the like.

[0078] See also Figure 13 In one example of an electronic device 300 of the present invention, the electronic device 300 includes a working unit 310 and a battery pack 200. The working unit 310 is electrically connected to the battery pack 200 to obtain electrical energy. The working unit 310 can be a unit component that can obtain electrical energy from the battery pack 200 and perform corresponding operations, such as the blade rotation unit of a fan, the dust collection unit of a vacuum cleaner, or the wheel drive unit of an electric vehicle. The electronic device 300 can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. Vehicles can be fuel vehicles, gas vehicles or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles or extended-range vehicles, etc.; spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.; electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers, etc. The embodiment of the present invention does not impose any special restrictions on the above-mentioned electronic device 300. In one embodiment of the electronic device 300 of the present invention, the electronic device 300 is a vehicle, the working part 310 is the body of the vehicle, and the battery pack 200 is fixedly installed on the body, thereby providing driving force for the vehicle to realize the operation of the vehicle.

[0079] The present invention provides a secondary battery, battery pack, and electronic device. The cover plate assembly of the secondary battery includes a first cover plate and a second cover plate, each of which can be separately formed and then fixedly connected. Compared to a one-piece end cap design, this design not only allows for the optimized layout of multiple local features on the cover plate assembly by adjusting the connection position between the first and second cover plates, thereby facilitating the processing and forming of the local features, but also, because the first and second cover plates are separate structures, they can be made of different materials or thicknesses according to actual welding and strength requirements. Therefore, compared to an integrated end cap design, the split cover plate assembly of the present invention offers greater flexibility and facilitates structural optimization of the secondary battery end cap. Therefore, the present invention effectively overcomes some practical problems in the prior art and has high utility value and practical significance. The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A secondary battery, characterized in that: include: The housing comprises a side wall with an opening at one end and a cover assembly, wherein the cover assembly seals the opening; an electrode assembly, disposed in the housing; Wherein, the cover plate assembly includes: a first cover plate, covering the opening and being sealed with 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.

2. The secondary battery according to claim 1, wherein The second cover plate includes an injection hole, and the second cover plate is arranged between the first cover plate and the electrode assembly, and the second cover plate and the inner wall of the through hole cooperate to form a step; the cover plate assembly also includes a sealing plate, the outer periphery of the sealing plate cooperates 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, wherein The secondary battery further includes a current collecting member electrically connected to the electrode assembly. The current collecting member is disposed between the electrode assembly and the second cover plate and welded to the second cover plate to form a first weld mark. The sealing plate covers the first weld mark.

4. The secondary battery according to claim 2, wherein: The first cover plate also includes a first protrusion and a cover body portion arranged around the outer periphery of the first protrusion, the first protrusion protrudes toward the second cover plate relative to the cover body portion, the through hole passes through the first protrusion, and the first protrusion is welded to the second cover plate on the side facing the electrode assembly.

5. The secondary battery according to claim 4, wherein The side of the first convex portion facing away from the electrode assembly includes a first concave portion, and the sealing plate is welded to the inner wall of the through hole to form a second weld mark, which is accommodated in the first concave portion, and the top of the second weld mark does not exceed the outer surface of the cover body facing away from the electrode assembly.

6. The secondary battery according to claim 1, wherein The secondary battery also includes a current collecting member, which is arranged on a side of the electrode assembly facing the cover plate assembly and is electrically connected to the electrode assembly; the outer periphery of the first cover plate is welded to the side wall, at least a portion of the current collecting member is exposed to the through hole, and the area of ​​the second cover plate that blocks the through hole is at least partially welded to the current collecting member.

7. The secondary battery according to claim 6, characterized in that The second cover plate is arranged on a side of the first cover plate away from the electrode assembly, and an outer edge of the second cover plate is abutted against and welded to the first cover plate.

8. The secondary battery according to claim 7, wherein: The second cover plate is welded to the current collecting member to form a first weld mark, which penetrates the second cover plate into the interior of the current collecting member and does not exceed the surface of the current collecting member facing the electrode assembly; the second cover plate is welded to the first cover plate to form a third weld mark, which penetrates the second cover plate into the interior of the first cover plate and does not exceed the surface of the first cover plate facing the electrode assembly.

9. The secondary battery according to claim 7, wherein The first cover plate includes a second recess and a cover body portion arranged around the outer periphery of the second recess, the second recess is recessed toward the electrode assembly side relative to the cover body portion, the second recess includes a bottom wall, the through hole passes through the bottom wall, the second cover plate is accommodated in the second recess and welded to the bottom wall.

10. The secondary battery according to any one of claims 6 to 9, characterized in that The melting point of the second cover plate is greater than the melting point of the current collecting member and is lower than the melting point of the first cover plate.

11. The secondary battery according to claim 10, wherein The second cover plate is made of one of nickel, carbon steel, iron, copper, copper-nickel alloy or iron-nickel alloy.

12. The secondary battery according to any one of claims 6 to 9, 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 any one of claims 6 to 9, characterized in that Along the axial direction of the secondary battery, the current collecting member includes a current collecting body and a thickened portion thicker than the current collecting body. The thickened portion protrudes toward the second cover plate relative to the current collecting body and abuts and welds to the second cover plate.

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

15. The secondary battery according to claim 1, wherein The ratio of the inner diameter of the through hole to the outer diameter of the first cover plate is less than or equal to 0.

5.

16. The secondary battery according to claim 15, characterized in that The secondary battery also includes a current collecting member, which is arranged on a side of the electrode assembly facing the cover plate assembly and is electrically connected to the electrode assembly to form a fourth weld mark; along the axial direction of the secondary battery, the orthographic projection of the first cover plate at least partially covers the fourth weld mark.

17. The secondary battery according to claim 15, characterized in that The cover plate assembly further includes an explosion-proof notch, which is arranged on the first cover plate.

18. A battery pack, characterized in that: A secondary battery comprising the secondary battery according to any one of claims 1 to 17.

19. An electronic device, characterized in that: A battery pack comprising the battery pack of claim 18.

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