Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a secondary battery which comprises the following components: a housing which comprises a housing body and a cover plate, one end of the housing body is provided with an opening, and the cover plate covers the opening and is connected with the housing body; the electrode assembly is accommodated in the shell, and the electrode assembly comprises a tab facing the cover plate; the current collecting component comprises a switching piece welded with the tab and a welding block surrounding the switching piece, the welding block is provided with a first step structure, the edge part of the switching piece is matched with the first step structure and is connected with the first step structure through welding, and the welding block is welded with the shell. The utility model aims to provide a secondary battery, a battery pack and an electronic device so as to at least realize fine positioning between a welding block and an adapter piece of a current collecting component.

Description

Technical Field

[0001] This utility model relates to a secondary battery, a battery pack, and an electronic device. Background Technology

[0002] In the field of new energy power batteries, secondary batteries generally include electrode components, a casing, and current collectors. The electrode components consist of positive and negative electrode plates, and a separator located between them. These positive and negative electrode plates and the separator are stacked and wound to form the electrode components, which are then encapsulated within the casing. Secondary batteries typically have current collectors near the opening of the casing. One end of the current collector is welded to the casing or end cap, and the other end is electrically connected to the tabs of the electrode components, thus achieving electrical connection between the casing and the electrode components. Utility Model Content

[0003] In view of the problems existing in the related technologies, the purpose of this utility model is to provide a secondary battery, battery pack and electronic device, so as to at least achieve precise positioning between the welding block and the adapter piece of the current collector.

[0004] To achieve the above objectives, this utility model provides a secondary battery, comprising: a casing, including a housing and a cover plate, one end of the housing forming an opening, the cover plate covering the opening and connecting to the housing; an electrode assembly, housed within the housing, the electrode assembly including tabs facing the cover plate; and a current collector, including an adapter piece welded to the tabs and a welding block surrounding the adapter piece, the welding block having a first stepped structure, the edge of the adapter piece engaging with the first stepped structure and being connected by welding, and the welding block being welded to the casing.

[0005] In some embodiments, the welding block is welded to the cover plate, wherein the thickness of the welding block is greater than the thickness of the cover plate in the thickness direction; or / and the welding block is welded to the housing, wherein the thickness of the welding block is greater than the thickness of the housing in the thickness direction.

[0006] In some embodiments, the welding block is welded to the cover plate, and the welding block and the cover plate are made of the same material; or / and the welding block is welded to the housing, and the welding block and the housing are made of the same material.

[0007] In some embodiments, the adapter piece is located between the first stepped structure and the cover plate, the weld marks of the adapter piece and the solder block face the cover plate, and the end face of the solder block facing the cover plate extends beyond the edge of the adapter piece along the direction from the current collector to the cover plate; or the adapter piece is located between the first stepped structure and the electrode assembly, the weld marks of the adapter piece and the solder block face the electrode assembly, and the end face of the solder block facing the electrode assembly extends beyond the edge of the adapter piece along the direction from the current collector to the electrode assembly.

[0008] In some embodiments, the weld block includes a second step structure connecting the first step structure and the end face.

[0009] In some embodiments, the weld block has a groove at the corner of the first stepped structure that is recessed away from the edge of the adapter piece.

[0010] In some embodiments, the adapter has a main body portion connected to the electrode tab and a bent portion disposed between the main body portion and the edge portion, the bent portion causing the main body portion to protrude toward the electrode assembly relative to the edge portion.

[0011] In some embodiments, the edge of the adapter piece is located between the solder block and the cover plate.

[0012] In some embodiments, the first step structure connects the end face of the welding block, the end face facing the electrode assembly, and the end face is flush with the surface of the adapter plate facing the electrode assembly.

[0013] Embodiments of this application also provide a battery pack, including any of the above-described secondary batteries.

[0014] Embodiments of this application also provide an electronic device including the battery pack described above.

[0015] The beneficial technical effects of this utility model are as follows:

[0016] The embodiments of this application provide a welding block with an annular first step structure. The first step structure cooperates with the edge of the adapter piece, so that the adapter piece overlaps on the first step structure, thereby achieving precise positioning between the welding block and the adapter piece. Moreover, this positioning method is simple to assemble and has high feasibility for mass production. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application 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 some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram is shown when the electronic device according to an embodiment of this application is a vehicle.

[0019] Figure 2 A perspective view of a secondary battery according to an embodiment of this application is shown.

[0020] Figure 3 The front view of the secondary battery is shown.

[0021] Figure 4 It shows along Figure 3 The cross-sectional view taken from line AA.

[0022] Figure 5 It shows Figure 4 A magnified view of region B in the middle.

[0023] Figure 6 A cross-sectional perspective view of a portion of a secondary battery according to an embodiment of this application is shown.

[0024] Figure 7 The front view of the flow collector component is shown.

[0025] Figure 8 It shows along Figure 7 A cross-sectional view taken from the CC line.

[0026] Figure 9 It shows Figure 8 A magnified view of region D in the middle.

[0027] Figure 10 A cross-sectional perspective view of a portion of a secondary battery according to an embodiment of this application is shown.

[0028] Figure 11 It shows Figure 10 A magnified view of region I in the middle.

[0029] Figure 12 A three-dimensional view of the flow collector component is shown.

[0030] Figure 13 The front view of the flow collector component is shown.

[0031] Figure 14 It shows along Figure 13 A cross-sectional view taken from the GG line.

[0032] Figure 15 It shows Figure 14 A magnified view of region H in the middle.

[0033] Figure 16 A cross-sectional perspective view of a portion of a secondary battery according to an embodiment of this application is shown.

[0034] Figure 17 The front view of the flow collector component is shown.

[0035] Figure 18 It shows along Figure 17 A cross-sectional view of the EE line.

[0036] Figure 19 It shows Figure 18 A magnified view of region F in the middle. Detailed Implementation

[0037] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0038] Embodiments of this application will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions are indicated by similar reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative and diagrammatic in nature and are intended to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.

[0039] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate minor variations. When used in conjunction with an event or situation, these terms may refer to examples in which the event or situation occurred precisely or in examples in which the event or situation occurred very approximately.

[0040] In this specification, unless otherwise specified or limited, relative terms such as “central,” “longitudinal,” “lateral,” “front,” “rear,” “right,” “left,” “inner,” “outer,” “lower,” “higher,” “horizontal,” “vertical,” “above,” “below,” “above,” “below,” “top,” “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to the directions described in the discussion or depicted in the accompanying drawings. These relative terms are used for descriptive convenience only and do not require that this application be constructed or operated in a particular orientation.

[0041] For ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0042] In existing secondary batteries, the cover plate and casing are welded together. In large cylindrical batteries, the negative electrode current collector, which connects to the negative electrode tab, is welded to the cover plate. The current path goes through the current collector to the cover plate and then to the casing, making the casing negatively charged. The thickness of the current collector in existing technology is typically 0.2mm, and the material is usually nickel-plated copper. The cover plate and current collector are welded using laser penetration welding. The laser strikes from the outside of the cover plate towards the inside, penetrating the cover plate before reaching the current collector for welding. The cover plate is typically 0.6mm thick, and the material is usually steel. Due to the thickness of the cover plate, a higher energy laser is required for welding. However, because the current collector is thinner, the laser may directly puncture the current collector, thereby directly damaging the electrode tabs, active materials, etc., posing a risk of rendering the secondary battery unusable.

[0043] Currently, the industry uses composite current collectors to solve this problem. A composite current collector consists of a thickened solder block and a current collector body. The thickened solder block is less likely to be welded through when welded to the cover plate. The solder block and the current collector body are composited by welding. If the solder joint between the solder block and the current collector body faces the cover plate, the solder joint may expand and protrude because the welded surface is not completely flat. This protruding solder joint may interfere with the cover plate, resulting in a gap between the composite current collector and the cover plate, leading to poor welding. If the solder joint between the solder block and the current collector body faces the electrode tabs of the electrode assembly, it will damage the tabs. Additionally, the solder joint may form air bubbles. If the secondary battery is vibrated, solder slag may fall and get into the electrode assembly, puncturing the tabs. In addition, in some embodiments of the prior art, there is no positioning structure between the welding block and the collector plate body, which makes the process difficult to implement and may cause eccentricity during welding. In other embodiments of the prior art, the positioning structure is difficult to assemble and industrialize, and the welding block and the collector plate body are not welded but only mechanically connected, resulting in a large contact resistance.

[0044] This utility model provides an electronic device 1000. For ease of explanation, the following embodiments use a vehicle as an example to illustrate the electronic device 1000. See also... Figure 1 The vehicle has a battery pack 1002 installed inside, which can be located at the bottom, front, or rear of the vehicle body 1001. The battery pack 1002 can be used to power the vehicle; for example, it can serve as the vehicle's operating power source. The working part of the electronic device 1000 is electrically connected to the battery pack 1002 to obtain electrical power. The vehicle can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, but are not limited thereto. The working part is the vehicle body, and the battery pack 1002 is located at the bottom of the vehicle body, providing electrical power for the vehicle's movement or the operation of its internal electrical components. However, in some other embodiments, the electronic device 1000 can also be a mobile phone, portable device, laptop, ship, spacecraft, electric toy, and power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working part can obtain electrical energy from the battery pack 1002 and perform corresponding functions, such as a fan blade rotation unit or a vacuum cleaner's suction unit. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat 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 application does not impose any special limitations on the aforementioned electronic device 1000.

[0045] Figure 2 A perspective view of a secondary battery 100 according to an embodiment of this application is shown. Figure 3 A front view of the secondary battery 100 is shown. Figure 4 It shows along Figure 3 The cross-sectional view taken from line AA. Figure 5 It shows Figure 4 Enlarged view of region B. An embodiment of this application provides a secondary battery 100, which includes a casing, an electrode assembly 120 located within the casing, and a current collector 130. The casing includes a housing 200 and a cover plate 140. The housing 200 includes a side wall 112, one end of which forms an opening 113. The cover plate 140 covers the opening 113 and connects to the side wall 112. The electrode assembly 120 is housed within the housing 200 and includes a tab (e.g., a negative tab) facing the opening 113 and the cover plate 140. The current collector 130 is made of copper, or nickel-plated on the copper surface. The cover plate 140 is made of stainless steel or nickel-plated steel.

[0046] As long as a stable sealing and electrical connection can be formed, the connection between the end wall 111 and the side wall 112 can be achieved in various ways, such as integral stamping, integral casting, or separate welding. The circumference of the side wall 112 is not limited; it can be cylindrical or prismatic, or follow any other closed-loop contour that matches the end wall. A receiving cavity is formed within the housing 200 to accommodate the electrode assembly 120, electrolyte, lower plastic, current collector 130, and other necessary battery components. Specifically, the diameter of the housing 200 can be determined according to the specific dimensions of the electrode assembly. The housing 200 can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, general-purpose cold-rolled carbon steel sheet and strip of grade SPCC, etc. To prevent rusting of the housing 200 during long-term use, a rust-preventive material such as metallic nickel can be plated on the surface of the housing 200. The secondary battery 100 can be a cylindrical battery, such as a 4680 cylindrical battery with a height of 80mm and a diameter of 46mm; or a battery with a height of 15mm and a diameter of 46mm.

[0047] Electrode assemblies are components in the secondary battery 100 where electrochemical reactions occur. The housing 200 may contain one or more electrode assemblies. The electrode assembly is a wound or stacked electrode assembly, including a stacked and / or wound positive electrode, a first separator, a negative electrode, and a second separator. The positive electrode includes a positive current collector and a positive active material layer coated on the positive current collector. A first coated area coated with the positive active material layer and a first uncoated area without the positive active material layer are formed on the positive current collector. The first coated area and the first uncoated area are arranged along the height direction of the electrode assembly. The first uncoated area extends beyond the separator at one end in the height direction of the secondary battery 100, forming a bent positive electrode tab. The negative electrode includes a negative current collector and a negative active material layer coated on the negative current collector. A second coated area with the negative active material layer and a second uncoated area without the negative active material layer are formed on the negative current collector. The second coated area and the second uncoated area are arranged along the height direction of the electrode assembly. The second uncoated area also extends towards one end of the secondary battery 100 in the height direction to the outside of the separator, forming a bent negative electrode tab. The first separator and the second separator are disposed between the positive electrode and the negative electrode to isolate the positive and negative active material layers. Taking the lithium-ion secondary battery 100 as an example, the material of the positive current collector can be 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 material of the negative current collector can be copper, and the negative active material layer includes negative active material, which can be carbon or silicon, etc. The substrate material of the first separator and the second separator can be PP (polypropylene) or PE (polyethylene), etc. To protect and insulate the electrode assembly, an insulating film can be wrapped around the outside of the electrode assembly. The insulating film can be synthesized from PP, PE, PET, PVC or other polymer materials.

[0048] Figures 6 to 9 , Figures 10 to 15 , Figures 16 to 19 The current collection components 130 according to the first to third embodiments of this application are shown respectively.

[0049] For the first embodiment, Figure 6 A cross-sectional perspective view of a portion of a secondary battery 100 according to an embodiment of this application is shown, illustrating the fit between the current collector 130, the housing 200, and the cover plate 140. Figure 7 The front view of the manifold component 130 is shown. Figure 8 It shows along Figure 7 A cross-sectional view taken from the CC line. Figure 9 It shows Figure 8The enlarged view of region D shows the current collector 130, the adapter piece 10, and the solder block 20. The adapter piece 10 is used for welding to the tab of the electrode assembly 120, and the solder block 20 is used for welding to the outer casing. The solder block 20 surrounds the adapter piece 10 and is provided with a first step structure 21 that mates with the edge portion 12 of the adapter piece 10. The edge portion 12 and the first step structure 21 are connected together by welding. The embodiments of this application provide a solder block 20 with an annular first step structure 21. The first step structure 21 mates with the edge portion 12 of the adapter piece 10, so that the adapter piece 10 overlaps on the first step structure 21, achieving precise positioning between the solder block 20 and the adapter piece 10. This positioning method is simple to assemble and has high mass production feasibility. The solder block 20 and the adapter piece 10 are welded together at the contact position, resulting in low contact resistance.

[0050] See Figure 6 As indicated by arrow 61, the weld block 20 is welded to the cover plate 140 and / or the side wall 112. The welding method is, for example, laser penetration welding. In the welding direction, the thickness of the weld block 20 is greater than the thickness of the cover plate 140 and / or the side wall 112, resulting in a larger welding process window, making it less likely for the weld block 20 to be welded through, and leading to a high product welding yield. In other words, when the weld block 20 is welded to the cover plate 140, in the thickness direction of the cover plate 140 (i.e.,...) Figure 6 Welding is performed in the vertical direction shown. The thickness of the weld block 20 is greater than the thickness of the cover plate 140. When the laser strikes from the outside to the inside of the cover plate 140, the thickness of the weld block 20 is greater and it will not be penetrated by the laser. When the weld block 20 is welded to the side wall 112, welding is performed in the thickness direction of the side wall 112 of the housing 200 (i.e., the thickness direction of the side wall 112 is greater than the thickness of the cover plate 140). Figure 6Welding is performed radially (as shown). The thickness of the weld block 20 radially is greater than the thickness of the sidewall 112. When the laser strikes from the outside to the inside of the sidewall 112, the thickness of the weld block 20 is greater and it will not be penetrated by the laser. The weld block 20 is welded to the cover plate 140 and / or the edge of the sidewall 112 as shown by arrow 61. The cover plate 140 and the current collector 130 are connected in parallel for current flow. The current does not pass through the explosion-proof valve 63, and the current flow path is short, so the DC resistance (DCR) is small and the heat generation is also small. The explosion-proof valve 63 can be a continuous annular structure or a discontinuous structure. The explosion-proof valve 63 is located in a weak area of ​​the cover plate 140. When the gas pressure inside the secondary battery 100 exceeds a certain threshold, the explosion-proof valve 63 will rupture, and the gas pressure inside the secondary battery 100 will be discharged from the rupture, thereby preventing the secondary battery 100 from experiencing lateral heat propagation and causing more serious consequences. In addition, when the welding block 20 and the cover plate 140 and / or the shell 200 to which it is welded are made of dissimilar materials, the quality of the weld pool is poor and the welding strength is low. Therefore, in order to improve the welding quality, when welding block 20 is welded to cover plate 140, the welding block 20 and cover plate 140 can be made of the same material. When welding block 20 is welded to shell 200, the shell 200 can be made of the same material. When welding block 20 is welded to cover plate 140 and shell 200, the welding block 20 and cover plate 140 and shell 200 can be made of the same material.

[0051] See also Figures 6 to 9 The adapter piece 10 is located between the first step structure 21 and the cover plate 140. The thickness of the welding block 20 is greater than the thickness of the adapter piece 10. The adapter piece 10 and the welding block 20 are welded together, for example, at the position indicated by arrow 62. Therefore, the weld marks between the two face the cover plate 140. If the welding slag falls due to vibration or other reasons, the welding slag will not fall into the electrode assembly 120 below, thus avoiding damage to the electrode assembly 120 and improving the safety of the secondary battery 100.

[0052] See Figure 9The end face 26 of the weld block 20 facing the cover plate 140 extends beyond the edge portion 12 of the adapter piece 10. The weld block 20 also includes a second step structure 22 connecting the first step structure 21. Along the direction from the current collector 130 to the cover plate 140, the second step structure 22 extends beyond the edge portion 12 of the adapter piece 10. Therefore, the first step structure 21 and the adapter piece 10 can be separated from the cover plate 140, leaving space for the protrusion of the weld mark formed between the first step structure 21 and the adapter piece 10. The weld mark will not interfere with the cover plate 140, avoiding affecting the welding between the weld block 20 and the cover plate 140. In some embodiments, the second step structure 22 may not be provided, and the weld mark between the cover plate 140 and the weld block 20 and the adapter piece 10 may be blocked by increasing the depth of the first step structure 21. The depth of the first step structure 21 can be different from the thickness of the adapter piece 10 (when the second step structure 22 is not included, the depth of the first step structure 21 is greater than the thickness of the adapter piece 10; when the second step structure 22 is included, the depth of the first step structure 21 can be greater than or less than the thickness of the adapter piece 10, as long as the end face 26 extends beyond the edge portion 12 of the adapter piece 10). The sidewall of the edge portion 12 of the adapter piece 10 can also not contact the first step structure 21. As long as the two can cooperate, the precise positioning of the adapter piece 10 can be achieved. And when... Figure 9 When the two shapes are fitted together, that is, the depth of the first step structure 21 is the same as the thickness of the adapter piece 10, and the sidewall of the edge portion 12 of the adapter piece 10 contacts the first step structure 21, the butt welding between the two can be better realized.

[0053] The welding block 20 has a groove 24 at the corner of the first step structure 21 that is recessed away from the edge portion 12 of the adapter piece 10. During the material processing, it is difficult to process the first step structure 21 and the second step structure 22 into right angles. There is usually a rounded chamfer at the corner of the step structure (see the second step structure 22 for example). The diameter of the annular step structure gradually decreases from top to bottom at the rounded chamfer. This causes the edge portion 12 of the adapter piece 10 to terminate at the rounded chamfer when it mates with the first step structure 21, resulting in a large gap between the edge portion 12 and the first step structure 21, which affects the welding effect between the two. The part of the first step structure 21 that would have formed a rounded chamfer is removed to form the groove 24, so that the side wall of the first step structure 21 can be relatively straight. The diameter of the first step structure 21 remains basically unchanged, and it can mate more tightly with the edge portion 12 of the adapter piece 10.

[0054] See also Figure 9The adapter piece 10 has a main body 14 and a Z-shaped bend 16 disposed between the main body 14 and the edge portion 12. The main body 14 is used for welding to the tab of the electrode assembly 120. The bend 16 matches the shape of the solder block 20. The bend 16 causes the main body 14 to protrude toward the electrode assembly 120 relative to the edge portion 12, but not beyond the edge of the solder block 20, so as to avoid the current collector 130 occupying too much height space. On the one hand, when the secondary battery 100 is used in cycles, the gas generated inside the electrode assembly 120 is discharged from the tab. The bend 16 can release some of the stress on the adapter piece 10 and reduce the deformation of the adapter piece 10. Therefore, the deformation of the welding contact surface between the adapter piece 10 and the solder block 20 can be reduced. This can reduce the risk of solder detachment and improve the stability and reliability of the electrical connection between the solder block 20 and the adapter piece 10. On the other hand, when the adapter piece 10 is welded to the solder block 20 and the electrode tab respectively, the welding stress at different welding positions will be transmitted to each other. By providing the bending part 16, the mutual transmission of welding stress can be weakened, and the welding deformation of the adapter piece 10 itself can be reduced. Therefore, the risk of solder detachment at different welding positions on the adapter piece 10 can be further reduced. At the same time, when the secondary battery 100 is subjected to external vibration and impact, the bending part 16 can release a part of the deformation, reducing the deformation of the bending part 16 at the main body 14 and the edge 12, thereby ensuring the stability of the electrical connection between the solder block 20 and the electrode tab.

[0055] For the second embodiment, Figure 10 A cross-sectional perspective view of a portion of a secondary battery 100 according to an embodiment of this application is shown, illustrating the fit between the current collector 130, the housing 200, and the cover plate 140. Figure 11 It shows Figure 10 Enlarged view of region I in the middle. Figure 12 A perspective view of the current collection component 130 is shown. Figure 13 The front view of the manifold component 130 is shown. Figure 14 It shows along Figure 13 A cross-sectional view taken from the GG line. Figure 15 It shows Figure 14 A magnified view of region H in the middle. See also... Figure 11Compared with the first embodiment, the second embodiment differs in that the adapter piece 10 in the second embodiment is flat, the solder block 20 does not include the second step structure 22, the solder mark between the first step structure 21 and the adapter piece 10 faces the electrode assembly 120, the first step structure 21 connects the end face 26 of the solder block 20 facing the electrode assembly 120, the end face 26 is flush with the surface 28 of the adapter piece 10 facing the electrode assembly 120, the current collector 130 in the second embodiment occupies a smaller height in the secondary battery 100, and the height occupied by the second step structure 22 is reduced compared with the first embodiment. The secondary battery 100 in the second embodiment has a higher energy density, and the structure of the current collector 130 in the second embodiment is simpler.

[0056] For the third embodiment, Figure 16 A cross-sectional perspective view of a portion of a secondary battery 100 according to an embodiment of this application is shown, illustrating the fit between the current collector 130, the housing 200, and the cover plate 140. Figure 17 The front view of the manifold component 130 is shown. Figure 18 It shows along Figure 17 A cross-sectional view of the EE line. Figure 19 It shows Figure 18 Enlarged view of region F in the middle. Compared with the first embodiment, the third embodiment differs in that the adapter piece 10 is located between the first step structure 21 and the electrode assembly 120. The solder mark of the first step structure 21 of the adapter piece 10 and the solder block 20 faces the electrode assembly 120. The end face 26 of the solder block 20 facing the electrode assembly 120 extends beyond the edge portion 12 of the adapter piece 10. The solder block 20 includes a second step structure 22 connecting the first step structure 21. Along the direction from the current collector 130 to the electrode assembly 120, the second step structure 22 extends beyond the edge portion 12 of the adapter piece 10. After the adapter piece 10 and the solder block 20 are combined together, they are then assembled with the electrode assembly 120. The second step structure 22 leaves space for the possible protrusion of the solder mark to separate the solder mark and the electrode assembly 120, avoiding damage to the electrode assembly 120 by the solder mark and improving the safety of the secondary battery 100. Similar to the first embodiment, the third embodiment may also omit the second step structure 22 and instead deepen the first step structure 21 to block the solder marks between the electrode assembly 120 and the solder block 20 and the adapter piece 10.

[0057] exist Figure 9 In the first embodiment shown, the edge portion 12 of the adapter piece 10 is located between the solder block 20 and the cover plate 140. When the lower electrode assembly 120 generates gas and expands, it will push the adapter piece 10 upward. When the bent portion 16 deforms, it is not blocked by the solder block 20. Therefore, the buffering effect is better than that of the third embodiment.

[0058] Although not shown in the figures of the second and third embodiments, the groove 24 in the first embodiment may also be formed at the corner of the first step structure 21 in the second and third embodiments to reduce the assembly gap between the weld block 20 and the adapter piece 10, so as to facilitate butt welding.

[0059] The embodiments of this application provide a welding block 20 having an annular first step structure 21. The first step structure 21 cooperates with the edge portion 12 of the adapter piece 10, so that the adapter piece 10 overlaps on the first step structure 21, thereby achieving precise positioning between the welding block 20 and the adapter piece 10. Moreover, this positioning method is simple to assemble and has high feasibility for mass production.

[0060] Embodiments of this application also provide a battery pack 1002, including a secondary battery 100 as described above, and the battery pack 1002 may have the beneficial effects described above regarding the secondary battery 100.

[0061] Embodiments of this application also provide an electronic device 1000, including the aforementioned battery pack 1002, and the electronic device 1000 may have the beneficial effects described above regarding the secondary battery 100 and / or battery pack 1002.

[0062] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A secondary battery, characterized in that, include: An outer casing includes a housing and a cover plate, wherein one end of the housing forms an opening, and the cover plate covers the opening and connects to the housing; An electrode assembly, housed within the housing, the electrode assembly including tabs facing the cover plate; The current collector includes an adapter piece welded to the electrode tab and a welding block surrounding the adapter piece. The welding block has a first stepped structure. The edge of the adapter piece mates with the first stepped structure and is connected by welding. The welding block is welded to the outer shell.

2. The secondary battery according to claim 1, characterized in that, The welding block is welded to the cover plate, wherein the thickness of the welding block is greater than the thickness of the cover plate in the thickness direction; or / and The welding block is welded to the shell, and the thickness of the welding block is greater than the thickness of the shell in the thickness direction of the shell.

3. The secondary battery according to claim 1, characterized in that, The welding block is welded to the cover plate, and the welding block and the cover plate are made of the same material; or / and the welding block is welded to the shell, and the welding block and the shell are made of the same material.

4. The secondary battery according to claim 1, characterized in that, The adapter piece is located between the first stepped structure and the cover plate. The weld mark of the adapter piece and the weld block faces the cover plate. Along the direction from the current collector to the cover plate, the end face of the weld block facing the cover plate extends beyond the edge of the adapter piece. or The adapter piece is located between the first stepped structure and the electrode assembly. The solder joint of the adapter piece and the solder block faces the electrode assembly. Along the direction from the current collector to the electrode assembly, the end face of the solder block facing the electrode assembly extends beyond the edge of the adapter piece.

5. The secondary battery according to claim 4, characterized in that, The weld block includes a second step structure that connects the first step structure and the end face.

6. The secondary battery according to claim 1, characterized in that, The welding block has a groove at the corner of the first stepped structure that is recessed away from the edge of the adapter piece.

7. The secondary battery according to claim 1, characterized in that, The adapter has a main body portion that connects to the electrode tab and a bent portion disposed between the main body portion and the edge portion, the bent portion causing the main body portion to protrude toward the electrode assembly relative to the edge portion.

8. The secondary battery according to claim 7, characterized in that, The edge of the adapter piece is located between the weld block and the cover plate.

9. The secondary battery according to claim 1, characterized in that, The first step structure connects to the end face of the welding block, the end face facing the electrode assembly, and the end face is flush with the surface of the adapter plate facing the electrode assembly.

10. A battery pack, characterized in that, The secondary battery includes any one of claims 1 to 9.

11. An electronic device, characterized in that, Includes the battery pack as described in claim 10.

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