Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a secondary battery, a battery pack and an electronic device, the secondary battery comprises a shell, an electrode assembly and a current collecting component, the shell comprises a cover plate assembly and a side wall with an opening at one end, and the cover plate assembly seals the opening; the cover plate assembly comprises a first cover plate and a second cover plate, the opening is covered with the first cover plate, the first cover plate is welded to the side wall in a sealed mode, and the first cover plate comprises a first through hole; the second cover plate is connected with the first cover plate and at least partially shields the first through hole; the electrode assembly is accommodated in the shell, and one side, facing the opening, of the electrode assembly is provided with a first tab; the current collecting component is arranged at one end, facing the opening, of the electrode assembly and is electrically connected with the first tab; the current collecting component comprises a convex part, and the convex part protrudes towards the side away from the electrode assembly and is welded to the first cover plate and / or the second cover plate. The technical problem that the welding heat conducted to the electrode assembly is large in the welding process of the current collecting component and the cover plate assembly can be solved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a secondary battery, battery pack, and electronic device. Background Technology

[0002] Existing secondary batteries generally have a cover plate assembly and a current collector at the open end of the casing. The cover plate assembly is used to seal the opening, and the current collector is used to weld to the cover plate assembly and the electrode assembly, respectively, thereby realizing the electrical connection between the cover plate assembly and the electrode assembly.

[0003] In existing structures, when current collectors are welded to cover plate assemblies, the welding position is usually close to the electrode tab. During the welding process, a large amount of welding heat is transferred to the electrode assembly side, which has a significant thermal impact on the electrode assembly. This increases the probability of thermal deformation and thermal damage to the electrode assembly, thereby reducing the performance and safety of the secondary battery. Utility Model Content

[0004] This invention provides a secondary battery, a battery pack, and an electronic device to improve the technical problem of excessive welding heat conducted to the electrode assembly during the welding process of the current collector and the cover plate assembly.

[0005] To achieve the above and other related objectives, this utility model provides a secondary battery, comprising: a housing, an electrode assembly, and a current collector. The housing includes a cover assembly and a sidewall with an opening at one end, the cover assembly sealing the opening; the cover assembly includes a first cover plate and a second cover plate, the first cover plate covering the opening and being sealed and welded to the sidewall, the first cover plate including a first through hole; the second cover plate being disposed on the side of the first cover plate opposite to the opening and connected to the first cover plate, and at least partially obscuring the first through hole; the electrode assembly being housed within the housing, the electrode assembly having a first tab on the side facing the opening; the current collector being disposed at the end of the electrode assembly facing the opening and electrically connected to the first tab; wherein, the current collector includes a protrusion, the protrusion protruding on the side opposite to the electrode assembly and being welded to the first cover plate and / or the second cover plate.

[0006] In one example of the secondary battery of this utility model, the second cover plate includes a second through hole, at least a portion of the second cover plate extends between the first through hole and the current collector, and cooperates with the inner wall of the first through hole to form a first stage; the cover plate assembly also includes a sealing plate, the outer periphery of the sealing plate cooperates with the first stage and is welded to the inner wall of the first through hole to seal the second through hole.

[0007] In one example of the secondary battery of this utility model, at least a portion of the protrusion is exposed to the second through hole and cooperates with the inner wall of the second through hole to form a second stage. The inner wall of the second through hole is welded to the protrusion to form a first weld mark, and the first weld mark is located within the second stage.

[0008] In one example of the secondary battery of this utility model, at least a portion of the protrusion is located between the second cover plate and the electrode assembly, and is welded to the second cover plate to form a first weld mark. The first weld mark penetrates the second cover plate into the interior of the protrusion but does not extend beyond the surface of the protrusion facing the electrode assembly.

[0009] In one example of the secondary battery of this utility model, the second cover plate is welded to the first cover plate to form a second weld mark. The second 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 away from the electrode assembly.

[0010] In one example of the secondary battery of this utility model, 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.

[0011] In one example of the secondary battery of this utility model, the thickness of the second cover plate is less than the thickness of the first cover plate.

[0012] In one example of the secondary battery of this utility model, at least a portion of the protrusion is located between the first cover plate and the electrode assembly, and is welded to the first cover plate to form a third weld mark. The third weld mark penetrates the first cover plate into the interior of the protrusion and does not exceed the surface of the protrusion facing the electrode assembly.

[0013] In one example of the secondary battery of this utility model, the second cover plate is at least partially sandwiched between the protrusion and the first cover plate. The first cover plate, the second cover plate and the protrusion are welded to form a fourth weld mark. The fourth weld mark penetrates the first cover plate and the second cover plate in sequence, and enters the interior of the protrusion without exceeding the surface of the protrusion facing the electrode assembly.

[0014] In one example of the secondary battery of this utility model, the current collector also includes a current collector body, which is welded to the first electrode tab, and the protrusion is connected to the current collector body, and the thickness of the protrusion is greater than the thickness of the current collector body.

[0015] This utility model also provides a battery pack, which includes any of the above-mentioned secondary batteries.

[0016] This invention also provides an electronic device that includes the aforementioned battery pack.

[0017] This utility model of a secondary battery, by providing a protrusion on the current collector component, with the protrusion facing away from the electrode assembly and welded to the first cover plate and / or the second cover plate, increases the distance between the welding point between the current collector component and the first and / or second cover plate and the electrode assembly. This reduces the transfer of welding heat generated at the welding point to the electrode assembly, decreasing the probability of thermal deformation and damage to the electrode assembly, thereby improving the performance and safety of the secondary battery. Furthermore, since the cover plate assembly includes a separate first cover plate and a second cover plate, which can be formed separately and then fixedly connected, the separate design of the cover plate assembly offers greater flexibility compared to a one-piece end cap design, facilitating structural optimization of the secondary battery on the end cap side. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a cross-sectional view of the overall structure of an embodiment of the secondary battery of this utility model;

[0020] Figure 2 for Figure 1 A magnified view of a section at point A in the central region;

[0021] Figure 3 This is a partial installation diagram of the first cover plate and the second cover plate after removing the sealing plate in one embodiment of the secondary battery of this utility model;

[0022] Figure 4 This is a schematic diagram of the electrode assembly structure of an example of the secondary battery of this utility model;

[0023] Figure 5 This is a schematic diagram showing the welding position of the protrusion and the second cover plate in an example of the secondary battery of this utility model;

[0024] Figure 6 This is a schematic diagram showing the welding position of the protrusion and the second cover plate in another example of the secondary battery of this utility model;

[0025] Figure 7 This is a schematic diagram showing the welding position of the protrusion and the second cover plate in another example of the secondary battery of this utility model;

[0026] Figure 8 This is a schematic diagram showing the welding position of the protrusion and the first cover plate in an example of the secondary battery of this utility model;

[0027] Figure 9 This is a schematic diagram showing the welding position of the protrusion to the first cover plate in another example of the secondary battery of this utility model;

[0028] Figure 10 This is a schematic diagram showing the welding positions of the protrusion to the first cover plate and the second cover plate in an example of the secondary battery of this utility model;

[0029] Figure 11 This is a schematic diagram showing the welding positions of the protrusion to the first cover plate and the second cover plate in another example of the secondary battery of this utility model;

[0030] Figure 12 This is a schematic diagram of an example of the battery pack of this utility model;

[0031] Figure 13 This is a schematic diagram of an example of the electronic device of this utility model.

[0032] Component designation explanation:

[0033] 100. Secondary battery; 110. Casing; 111. Side wall; 112. Opening; 113. End wall; 120. Electrode assembly; 121. Positive electrode; 1211. Positive current collector; 1212. First coated area; 1213. First uncoated area; 122. Separator; 123. Negative electrode; 1231. Negative current collector; 1232. Second coated area; 1233. Second uncoated area; 124. Negative electrode tab; 125. Positive electrode tab; 130. Current collector component; 131. Protrusion; 132. Current collector body; 13 3. Opening; 140. Cover plate assembly; 141. First cover plate; 1411. First through hole; 142. Second cover plate; 1421. Second through hole; 1422. First stage; 1423. Second stage; 1424. Positioning groove; 150. Sealing plate; 161 / 161'. First weld mark; 162. Second weld mark; 163. Third weld mark; 164. Fourth weld mark; 200. Battery pack; 210. Housing; 211. First housing section; 212. Second housing section; 300. Electronic device; 310. Working part. Detailed Implementation

[0034] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. It should also be understood that the terminology used in the embodiments of this utility model is for describing specific implementation schemes and not for limiting the scope of protection of this utility model. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0035] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise specified in this invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, equipment, and materials similar to or equivalent to those in the embodiments of this invention.

[0036] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" used in this specification are only for clarity of description and are not intended to limit the scope of implementation of this utility model. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of implementation of this utility model.

[0037] Please see Figures 1 to 13 This utility model provides a secondary battery 100, a battery pack 200, and an electronic device 300. The current collector 130 in the secondary battery 100 is provided with a protrusion 131 that protrudes away from the electrode assembly 120. The cover plate assembly 140 is welded to the protrusion 131, which can increase the distance between the welding position of the current collector 130 and the cover plate assembly 140 and the electrode assembly 120, thereby reducing the transfer of welding heat generated at the welding position to the electrode assembly 120 and improving the performance and safety of the secondary battery 100.

[0038] In this invention, the secondary battery 100 may include lithium-ion batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this invention are not limited to this. The secondary battery 100 may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this invention are not limited to this either.

[0039] Please see Figure 1The structure of the secondary battery 100 is further described, which includes: a housing 110, an electrode assembly 120, and a current collector 130.

[0040] The housing 110 has a mounting cavity for mounting 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, a diameter of 46 mm and heights of 80 mm, 95 mm, or 120 mm. The housing 110 can be of various shapes, such as cylindrical or prismatic. The housing 110 can also be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy. To prevent rusting during long-term use, a rust-preventive material, such as nickel, can be plated onto the surface of the housing 110.

[0041] Please see Figure 1 In one embodiment of the secondary battery 100 of this utility model, the housing 110 has a cylindrical structure and includes an end wall 113, a side wall 111 surrounding the end wall 113, and a cover 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 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.

[0042] Please see Figure 1 and Figure 4 The electrode assembly 120 is disposed inside the housing 110 and is a component in the secondary battery 100 where electrochemical reactions occur. The housing 110 may contain one or more electrode assemblies 120. The electrode assembly 120 includes an electrode sheet and a separator 122, which are wound together to form a wound structure. Specifically, in this embodiment, the electrode assembly 120 includes a positive electrode sheet 121, a separator 122, and a negative electrode sheet 123 wound axially around the housing 110.

[0043] Please see Figure 4 The positive electrode 121 includes a positive current collector 1211 and a positive active material layer coated on the positive current collector 1211. The positive current collector 1211 has a first coated area 1212 coated with the positive active material layer and a first uncoated area 1213 uncoated with the positive active material layer. The first coated area 1212 and the first uncoated area 1213 are arranged along the axial direction of the housing 110. The first uncoated area 1213 extends to one end of the secondary battery 100 in the height direction to the outside of the separator 122 and is bent towards the axis of the housing 110 to form a stacked positive electrode tab 125.

[0044] Please continue reading. Figure 4The negative electrode 123 includes a negative current collector 1231 and a negative active material layer coated on the negative current collector 1231. A second coated area 1232 coated with the negative active material layer and a second uncoated area 1233 uncoated with the negative active material layer are formed on the negative current collector 1231. The second coated area 1232 and the second uncoated area 1233 are arranged along the axial direction of the housing 110. The second uncoated area 1233 extends to the other end of the secondary battery 100 in the height direction to the outside of the separator 122 and is bent towards the axis of the housing 110 to form a stacked negative electrode tab 124.

[0045] Please continue reading. Figure 4 A separator 122 is disposed between the positive electrode 121 and the negative electrode 123 to isolate the positive and negative active material layers. Taking a lithium-ion secondary battery 100 as an example, the positive current collector 1211 can be made of aluminum, and the positive active material layer includes positive active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative current collector 1231 can be made of copper, and the negative active material layer includes negative active material, which can be carbon or silicon, etc. The substrate material of the separator 122 can be polypropylene (PP) or polyethylene (PE), etc. To protect and insulate the electrode assembly 120130, an insulating film can be wrapped around the outside of the electrode assembly 120130. The insulating film can be synthesized from PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC) or other polymer materials.

[0046] Please continue reading. Figure 1 and Figure 4 In one example of the secondary battery 100 of this utility model, the electrode assembly 120 is sealed and installed inside the housing 110. The electrode assembly 120 has a first electrode tab and a second electrode tab respectively at both ends in the height direction of the secondary battery 100, and the first electrode tab and the second electrode tab have opposite polarities. The first electrode tab faces the opening 112 of the housing 110, and the first electrode tab is a negative electrode tab 124. It should be noted that in other embodiments, the first electrode tab can also be a positive electrode tab 125, and the second electrode tab can be a negative electrode tab 124.

[0047] Please see Figure 1In one example of the secondary battery 100 of this utility model, a through terminal mounting hole is provided on the end wall 113 of the housing 110. The electrode terminal 170 is sealed and insulatedly installed in the terminal mounting hole. As long as the electrode terminal 170 and the end wall 113 can be sealed and insulated, the installation method of the electrode terminal 170 on the end wall 113 is not limited. The electrode assembly 120 has a second tab on the side facing the end wall 113. The second tab is a positive tab 125. One end of the electrode terminal from 170 can be directly welded to the second tab, or it can be electrically connected to the second tab through a current collector. There is no specific limitation on this.

[0048] Please see Figures 1 to 3 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 and welded to the side wall 111 of the housing 110. The first cover plate 141 includes a first through hole 1411, which can be located in the central region of the first cover plate 141 or off-center. The shape of the first through hole 1411 can also be various, such as a square hole, a round hole, or other irregular holes. Preferably, in order to facilitate the machining and positioning of the first through hole 1411 on the first cover plate 141, in this embodiment, the first through hole 1411 is a round hole structure, and the first through hole 1411 is coaxially arranged with the first cover plate 141.

[0049] Please see Figure 2 and Figure 3 The second cover plate 142 is disposed on the side of the first cover plate 141 opposite to the opening 112, that is, on the side of the first cover plate 141 facing the electrode assembly 120. The second cover plate 142 at least partially covers the first through hole 1411. The second cover plate 142 is connected to the first cover plate 141, and the connection method can be any method that can realize the electrical connection between the first cover plate 141 and the second cover plate 142, such as welding connection or riveting connection.

[0050] Please see Figure 2 and Figure 3 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 a disc shape that matches the first through hole 1411, or it can be other shapes that can at least partially cover the first through hole 1411, such as a rectangular plate, a polygonal plate, etc. Preferably, in this embodiment, the outer contour of the second cover plate 142 is an approximately circular contour and is coaxially arranged with the first through hole 1411. This facilitates the positioning and installation of the second cover plate 142 and the first cover plate 141, and helps to improve the assembly efficiency between the second cover plate 142 and the first cover plate 141.

[0051] Please see Figure 2The current collector 130 is disposed within the housing 110 and located on the side of the electrode assembly 120 facing the opening 112. The current collector 130 is electrically connected to the first electrode tab, i.e., electrically connected to the negative electrode tab 124. The electrical connection can be achieved through various methods such as conductive adhesive bonding or welding. Preferably, in this embodiment, the current collector 130 is welded to the first electrode tab to achieve the electrical connection. The specific location and welding area of ​​the current collector 130 to the first electrode tab are not limited, as long as a stable electrical connection between the current collector 130 and the first electrode tab can be achieved.

[0052] The current collector 130 includes a current collector body 132 and a protrusion 131. The current collector body 132 is welded to the first electrode tab, and the protrusion 131 is fixedly connected to the current collector body 132, with the protrusion 131 protruding towards the side opposite to the electrode assembly 120. The protrusion 131 and the current collector body 132 can be an integral structure, such as an integral stamped part or an integral cast part. Alternatively, the protrusion 131 and the current collector body 132 can be two separate parts, fixedly connected by welding or riveting. The protrusion 131 can be a ring structure surrounding the center of the current collector 130, or it can be multiple block structures spaced apart around the center of the current collector 130. Optionally, in this embodiment, to facilitate the forming and processing of the protrusion 131, the protrusion 131 is a ring structure surrounding the center of the current collector 130, and the protrusion 131 and the first cover plate 141 are approximately coaxial. The protrusion 131 is welded to the cover plate assembly 140. The welding position between the protrusion 131 and the cover plate assembly 140 is not limited. For example, in one embodiment, the protrusion 131 may abut and be welded to the second cover plate 142. In another embodiment, the protrusion 131 may abut and be welded to the first cover plate 141. In other embodiments, the protrusion 131 may also be stacked vertically with the first cover plate 141 and the second cover plate 142, so as to be welded to both the first cover plate 141 and the second cover plate 142 simultaneously.

[0053] In this embodiment, a protrusion 131 is provided on the current collector 130, and the protrusion 131 protrudes to the side away from the electrode assembly 120. The protrusion 131 is welded to the first cover plate 141 and / or the second cover plate 142. This increases the distance between the welding position of the current collector 130 and the first cover plate 141 and / or the second cover plate 142 and the electrode assembly 120. This reduces the transfer of welding heat generated at the welding position to the electrode assembly 120, reduces the probability of thermal deformation and thermal damage to the electrode assembly 120, and thus improves the performance and safety of the secondary battery 100. Meanwhile, since the cover assembly 140 includes a separate first cover plate 141 and a second cover plate 142, which can be formed separately and then fixedly connected together, this design allows for the processing and forming of multiple local feature structures on the cover assembly 140 by adjusting the connection position between the first cover plate 141 and the second cover plate 142. Furthermore, because the first cover plate 141 and the second cover plate 142 are separate structures, they can also be made of different materials or have different material thicknesses according to actual welding requirements and strength requirements. Compared to a one-piece end cap design, the separate design of the cover assembly 140 in this solution offers greater flexibility and facilitates structural optimization of the secondary battery 100 on the end cap side.

[0054] Please see Figure 2 and Figure 3In one example of the secondary battery 100 of this utility model, the second cover plate 142 includes a second through hole 1421, and the current collector 130 includes an opening 133, which communicates with the second through hole 1421 for injecting liquid into the electrode assembly 120. The second through hole 1421 can be located in the central region of the second cover plate 142 or in a region off-center from the center of the second cover plate 142, depending on whether it meets the liquid injection requirements of the electrode assembly 120. Optionally, in this embodiment, the second through hole 1421 is disposed in the central region of the second cover plate 142 and is coaxially disposed with the second cover plate 142. The cover plate assembly 140 also includes a sealing plate 150, which is disposed on the side of the second cover plate 142 away from the current collector 130, and the sealing plate 150 covers the second through hole 1421. Along the radial direction of the first cover plate 141, a portion of the second cover plate 142 extends between the first through hole 1411 and the current collector 130, and at least partially blocks the end of the first through hole 1411 facing the electrode assembly 120, so that the second cover plate 142 mates with the inner wall of the first through hole 1411 to form a first stage 1422. The outer periphery of the sealing plate 150 is accommodated within the first stage 1422 and mates with the first stage 1422. The outer periphery of the sealing plate 150 abuts against the inner wall of the first through hole 1411 to form a circumferentially arranged butt joint around the first through hole 1411, and a fifth weld mark 165 is formed at the butt joint position. The sealing plate 150 is welded to the inner wall of the first through hole 1411 through the fifth weld mark 165 to achieve the sealing of the second through hole 1421.

[0055] Since the first stage 1422 can be formed by the positional fit between the second cover plate 142 and the first through hole 1411, and the sealing plate 150 can be installed in the first stage 1422 to achieve the fitting installation of the sealing plate 150 on the cover plate assembly 140, it is not necessary to integrally stamp the first stage 1422 on the first cover plate 141 or the second cover plate 142. Therefore, the forming of the first stage 1422 can be facilitated, and the forming accuracy of the first stage 1422 can be ensured. This can improve the fitting accuracy between the sealing plate 150 and the first stage 1422, and ultimately improve the welding quality between the sealing plate 150 and the first stage 1422, ensuring the sealing performance of the sealing plate 150 on the second through hole 1421.

[0056] When the protrusion 131 and the second cover plate 142 are welded together, the welding method between the protrusion 131 and the second cover plate 142 can be various methods such as through welding and fillet welding. Optionally, please refer to [the relevant documentation]. Figure 2 and Figure 5In one example of the secondary battery 100 of this utility model, along the radial direction of the second cover plate 142, the inner edge of the protrusion 131 extends at least partially toward the center of the second through hole 1421 and is exposed to the second through hole 1421. That is, the side of the second through hole 1421 facing the electrode assembly 120 overlaps with the protrusion 131 so that the protrusion 131 and the inner wall of the second through hole 1421 cooperate to form a second stage 1423. The inner wall of the second through hole 1421 and the protrusion 131 are welded to form a fillet weld. For ease of description, the fillet weld formed by the welding of the inner wall of the second through hole 1421 and the protrusion 131 is marked as the first weld mark 161. The first weld mark 161 is located in the second stage 1423. The first weld mark 161 can be an annular weld mark surrounding the inner wall of the second through hole 1421, or it can be a plurality of discontinuous weld marks spaced apart around the inner wall of the second through hole 1421, specifically to meet the flow guidance requirements and connection strength between the second cover plate 142 and the flow collection member 130.

[0057] Since the protrusion 131 and the inner wall of the second through hole 1421 mate to form the second stage 1423, and the first weld mark 161 formed by welding the inner wall of the second through hole 1421 and the protrusion 131 is located within the second stage 1423, this arrangement allows for convenient and intuitive inspection of the fit between the second cover plate 142 and the protrusion 131, thereby ensuring welding yield. Simultaneously, after welding is completed, the quality of the first weld mark 161 can be intuitively inspected to promptly identify welding quality problems and welding position errors, further ensuring welding yield.

[0058] Optionally, please refer to Figure 6 and Figure 7 In one example of the secondary battery 100 of this utility model, during the welding of the protrusion 131 and the second cover plate 142, at least a portion of the protrusion 131 is located between the second cover plate 142 and the electrode assembly 120, and the side of the protrusion 131 facing away from the electrode assembly 120 is welded to the side of the second cover plate 142 facing the electrode assembly 120, forming a first weld mark 161'. The first weld mark 161' penetrates the second cover plate 142 into the interior of the protrusion 131 but does not extend beyond the surface of the protrusion 131 facing the electrode assembly 120. That is, the second cover plate 142 and the protrusion 131 are welded through, and the first weld mark 161' does not weld through the protrusion 131. With this configuration, when welding the protrusion 131 and the second cover plate 142, the welding head can be welded along the height direction of the housing 110 without needing to form an inclined welding posture with the housing 110. This not only simplifies the structure of the welding head but also reduces welding positioning errors, which is beneficial to improving the quality stability of the first weld mark 161'. Meanwhile, compared to fillet welding, the thickness of the second cover plate 142 can be reduced when through welding, which is more conducive to the lightweight design of the cover plate assembly 140.

[0059] Based on the welding of the protrusion 131 to the second cover plate 142, there are various welding methods between the first cover plate 141 and the second cover plate 142. For example, it can be a through weld between the first cover plate 141 and the second cover plate 142 on the first cover plate 141 side, or it can be a through weld between the first cover plate 141 and the second cover plate 142 on the second cover plate 142 side. Optionally, please refer to Figure 6 and Figure 7 In one example of the secondary battery 100 of this utility model, a second cover plate 142 is welded to a first cover plate 141 to form a second weld mark 162. The second weld mark 162 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 away from the electrode assembly 120. The welding position of the second weld mark 162 is located on the outer periphery of the protrusion 131, along the radial direction of the second cover plate 142. The second weld mark 162 can be located near the protrusion 131 or near the side wall 111 of the housing 110.

[0060] In this embodiment, since welding the second cover plate 142 to the first cover plate 141 and welding the second cover plate 142 to the protrusion 131 both require penetration of the second cover plate 142, the thickness of the second cover plate 142 can be reduced. This facilitates both the penetration welding of the first cover plate 141 and the second cover plate 142 and the penetration welding of the second cover plate 142 to the protrusion 131, thus simplifying the thickness selection design of the second cover plate 142. Simultaneously, since the welding between the second cover plate 142 and the first cover plate 141 must be completed before the cover plate assembly 140 is installed onto the housing 110, this avoids the thermal impact on the electrode assembly 120 during the forming process of the second solder mark 162, further ensuring the performance of the secondary battery 100.

[0061] Considering that in the secondary battery 100, the current collector 130 is mainly used for current conduction, it needs to have good current conduction performance and chemical corrosion resistance. The cover assembly 140, since it needs to be welded to the sidewall 111 to form part of the casing 110, needs to have high strength and good rust resistance. Therefore, the current collector 130 and the cover assembly 140 are generally not made of the same material. The current collector 130 is typically made of copper, nickel, aluminum, etc., while the cover assembly 140 is typically made of stainless steel. This results in difficulties in welding the current collector 130 and the cover assembly 140, and challenges in ensuring weld quality. Please refer to... Figure 6 and Figure 7In one example of the secondary battery 100 of this utility model, the melting point of the second cover plate 142 is greater than the melting point of the current collector 130 (i.e., greater than the melting point of the protrusion 131) and less than the melting point of the first cover plate 141. By making the melting point of the second cover plate 142 greater than the melting point of the current collector 130 and less than the melting point of the first cover plate 141, this setting allows the melting point of the second cover plate 142 to be between the melting points of the first cover plate 141 and the current collector 130, thereby reducing the melting point difference between the second cover plate 142 and the first cover plate 141, ensuring the welding quality between the second cover plate 142 and the first cover plate 141, and also reducing the melting point difference between the second cover plate 142 and the current collector 130, ensuring the welding quality between the second cover plate 142 and the current collector 130. This effectively solves the problem of high welding difficulty and difficulty in ensuring welding quality between the current collector 130 and the cover plate assembly 140.

[0062] Considering the common material properties of the first cover plate 141 and the current collector 130, preferably, in one example of the secondary battery 100 of this utility model, the material of the second cover plate 142 is any one of nickel, carbon steel, iron, copper, copper-nickel alloy, or iron-nickel alloy. The aforementioned materials not only ensure that the melting point of the second cover plate 142 is between that of the first cover plate 141 and the current collector 130, but also ensure that the second cover plate 142 has better electrical conductivity and corrosion resistance.

[0063] In one example of the secondary battery 100 of this utility model, 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 affects the strength of the cover plate assembly 140 at different locations. Figure 6 As shown, due to the different positions 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 greater pressure. Therefore, the first cover plate 141 needs to have greater supporting strength and rigidity to suppress the deformation of the secondary battery 100, so the thickness of the first cover plate 141 is correspondingly larger. The second cover plate 142 is located in the central area of ​​the first cover plate 141. Therefore, when the secondary battery 100 expands and deforms, the deformation is smaller than that of the first cover plate 141. Thus, the second cover plate 142 can have a smaller thickness. This arrangement, while ensuring that both the first cover plate 141 and the second cover plate 142 meet their respective strength requirements, can reduce the weight of the second cover plate 142, thereby facilitating the lightweight design of the secondary battery 100. Meanwhile, since the second cover plate 142 is thinner, it is more conducive to penetration welding with the first cover plate 141 and the current collection component 130.

[0064] Please see Figure 8 and Figure 9 In one example of the secondary battery 100 of this utility model, along the radial direction of the current collector 130, a protrusion 131 is disposed on the side of the current collector body 132 near the sidewall 111 of the housing 110. A second cover plate 142 is located within the inner circumferential region of the protrusion 131. A second weld mark 162 formed by welding the second cover plate 142 and the first cover plate 141 is located within the inner circumference of the protrusion 131. At least a portion of the protrusion 131 is located between the first cover plate 141 and the electrode assembly 120. The side of the protrusion 131 facing away from the electrode assembly 120 abuts against the side of the first cover plate 141 facing the electrode assembly 120 and welds them together to form a third weld mark 163. The third weld mark 163 penetrates the first cover plate 141 into the interior of the protrusion 131 but does not exceed the surface of the protrusion 131 facing the electrode assembly 120, that is, the third weld mark 163 does not weld through the protrusion 131. This design reduces the radial extension dimension of the second cover plate 142, thereby reducing the mass of the second cover plate 142 and facilitating the lightweight design of the secondary battery 100.

[0065] Please see Figure 10 and Figure 11 In one example of the secondary battery 100 of this utility model, at least a portion of the second cover plate 142 is sandwiched between the protrusion 131 and the first cover plate 141. That is, the side of the second cover plate 142 away from the electrode assembly 120 abuts against the first cover plate 141, and the side of the second cover plate 142 facing the electrode assembly 120 abuts against the protrusion 131. Along the height direction of the housing 110, the contact area between the second cover plate 142 and the first cover plate 141 and the contact area between the second cover plate 142 and the protrusion 131 at least partially overlap. The first cover plate 141, the second cover plate 142 and the protrusion 131 are welded together to form a fourth weld mark 164. The fourth weld mark 164 penetrates the first cover plate 141 and the second cover plate 142 in sequence, and enters the interior of the protrusion 131 without exceeding the surface of the protrusion 131 facing the electrode assembly 120. To facilitate the positioning of the second cover plate 142 with the first cover plate 141 and the protrusion 131, the second cover plate 142 may optionally be provided with a positioning groove 1424, and the protrusion 131 is engaged in the positioning groove 1424. This can ensure the positioning and assembly accuracy between the protrusion 131, the second cover plate 142 and the first cover plate 141, thereby improving the welding quality of the fourth solder mark 164 and ensuring the stability of the electrical connection between the cover plate assembly 140 and the current collector 130.

[0066] In this embodiment, since the fourth solder mark 164 sequentially penetrates the first cover plate 141 and the second cover plate 142 and enters the interior of the protrusion 131 without exceeding the surface of the protrusion 131 facing the electrode assembly 120, the welding between the first cover plate 141, the second cover plate 142 and the protrusion 131 can be achieved simultaneously through one welding (i.e., the fourth solder mark 164). This can save the pre-assembly welding process between the first cover plate 141 and the second cover plate 142, thereby reducing the production and assembly cost of the secondary battery 100.

[0067] To further reduce the probability of burn-through during the welding process between the protrusion 131 and the cover plate assembly 140, optionally, please refer to Figure 5 , Figure 7 , Figure 9 and Figure 11 In one example of the secondary battery 100 of this utility model, the thickness of the protrusion 131 is greater than the thickness of the current collector body 132. Since the thickness of the protrusion 131 is greater than the thickness of the current collector body 132, a local thickening area can be formed on the current collector component 130. When the cover plate assembly 140 and the protrusion 131 are penetrated and welded to the outside of the housing 110, the welding difficulty can be reduced, the welding process window can be increased, and the phenomenon of weld burn-through of the protrusion 131 can be reduced. This not only ensures the welding quality between the protrusion 131 and the cover plate assembly 140, but also avoids the probability of foreign objects such as welding slag generated during the welding process of the protrusion 131 entering the interior of the electrode assembly 120, thus better ensuring the service life of the secondary battery 100.

[0068] Please see Figure 12 In one embodiment of the battery pack 200 of this utility model, 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, which cover each other to form a receiving space. Multiple secondary batteries 100 are housed within the receiving space, and 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, etc.

[0069] Please see Figure 13In one example of the electronic device 300 of this utility model, the electronic device 300 includes a working part 310 and a battery pack 200. The working part 310 is electrically connected to the battery pack 200 to obtain electrical power. The working part 310 can be a unit component capable of obtaining electrical power from the battery pack 200 and performing corresponding work, such as a fan blade rotation unit, a vacuum cleaner suction unit, or a wheel drive unit in an electric vehicle. The electronic device 300 can be a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary 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. This utility model embodiment does not impose special limitations on the above-mentioned electronic device 300. In one embodiment of the electronic device 300 of this utility model, the electronic device 300 is a vehicle, the working part 310 is the vehicle body, and the battery pack 200 is fixedly installed on the vehicle body, thereby providing driving force for the vehicle to operate.

[0070] This utility model of a secondary battery, by providing a protrusion on the current collector component, with the protrusion facing away from the electrode assembly and welded to a first cover plate and / or a second cover plate, increases the distance between the welding position between the current collector component and the first and / or second cover plates and the electrode assembly. This reduces the transfer of welding heat generated at the welding position to the electrode assembly, decreasing the probability of thermal deformation and damage to the electrode assembly, thereby improving the performance and safety of the secondary battery. Furthermore, since the cover plate assembly includes a separate first cover plate and a second cover plate, which can be separately formed and then fixedly connected, the separate design of the cover plate assembly offers greater flexibility compared to a one-piece end cap design, facilitating structural optimization of the secondary battery on the end cap side. Therefore, this utility model effectively overcomes some practical problems in the prior art, thus possessing high utilization value and practical significance. The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit it. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model shall still be covered by the claims of this utility model.

Claims

1. A secondary battery characterized by comprising: The application relates to a secondary battery, comprising: a shell, which comprises a cover plate assembly and a side wall with an open end, the cover plate assembly sealing the open end; the cover plate assembly comprises a first cover plate and a second cover plate, the first cover plate covers the open end and is sealedly welded with the side wall, the first cover plate comprises a first through hole; the second cover plate is arranged on the side of the first cover plate away from the open end and is connected with the first cover plate and at least partially covers the first through hole; an electrode assembly contained in the shell, the electrode assembly has a first tab on the side facing the open end; a current collecting member arranged on the end of the electrode assembly facing the open end and electrically connected with the first tab; wherein the current collecting member comprises a protruding part which protrudes to the side away from the electrode assembly and is welded with the first cover plate and / or the second cover plate.

2. The secondary battery according to claim 1, characterized by The second cover plate comprises a second through hole, at least part of the second cover plate extends between the first through hole and the current collecting member and cooperates with the inner wall of the first through hole to form a first landing stage; the cover plate assembly further comprises a sealing plate, the outer periphery of the sealing plate cooperates with the first landing stage and is welded with the inner wall of the first through hole to seal the second through hole.

3. The secondary battery according to claim 2, characterized by At least part of the protruding part is exposed to the second through hole and cooperates with the inner wall of the second through hole to form a second landing stage, the inner wall of the second through hole is welded with the protruding part to form a first welding mark, and the first welding mark is located in the second landing stage.

4. The secondary battery according to claim 2, characterized by At least part of the protruding part is located between the second cover plate and the electrode assembly and is welded with the second cover plate to form a first welding mark, the first welding mark penetrates the second cover plate into the interior of the protruding part and does not exceed the surface of the protruding part facing the electrode assembly.

5. The secondary battery according to claim 4, characterized by The second cover plate is welded with the first cover plate to form a second welding mark, the second welding mark penetrates the second cover plate into the interior of the first cover plate and does not exceed the surface of the first cover plate away from the electrode assembly.

6. The secondary battery according to claim 5, characterized by The melting point of the second cover plate is greater than the melting point of the current collecting member and smaller than the melting point of the first cover plate.

7. The secondary battery according to claim 5, characterized by The thickness of the second cover plate is smaller than the thickness of the first cover plate.

8. The secondary battery according to claim 2, characterized by At least part of the protruding part is located between the first cover plate and the electrode assembly and is welded with the first cover plate to form a third welding mark, the third welding mark penetrates the first cover plate into the interior of the protruding part and does not exceed the surface of the protruding part facing the electrode assembly.

9. The secondary battery according to claim 2, characterized by The second cover plate is at least partially sandwiched between the protruding part and the first cover plate, the first cover plate, the second cover plate and the protruding part are welded to form a fourth welding mark, the fourth welding mark penetrates the first cover plate, the second cover plate and the interior of the protruding part in sequence and does not exceed the surface of the protruding part facing the electrode assembly.

10. The secondary battery according to any one of claims 1 to 9, characterized by The current collecting member further comprises a current collecting body, the current collecting body is welded with the first tab, the protruding part is connected with the current collecting body, and the thickness of the protruding part is greater than the thickness of the current collecting body.

11. A battery pack, characterized by The application further relates to a secondary battery comprising any one of the secondary batteries according to claims 1 to 10.

12. An electronic device, comprising: The application further relates to a battery pack comprising the battery according to claim 11.

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