Secondary batteries, battery packs and electronic devices

Abstract

This utility model provides a secondary battery, a battery pack, and an electronic device. The secondary battery includes: a casing, an electrode assembly, and a cover plate. The casing includes a surrounding sidewall with an opening at one end. The electrode assembly is installed inside the casing and includes a first electrode, a second electrode, and a separator layered and wound to form a wound structure. The first electrode includes a first current collector and a first active material. The first current collector includes a first coated area coated with the first active material and a first empty foil without active material. Multiple first empty foils are stacked and gathered to form a lead-out portion. The cover plate seals the opening and is connected to the sidewall by soldering. The lead-out portion is connected to the cover plate by soldering, and / or the lead-out portion is connected to the sidewall by soldering. This can improve the technical problems of complex assembly processes and numerous welding processes between the electrode assembly and the casing during the secondary battery production process.

Description

Technical Field

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

[0002] In existing cylindrical batteries, current collectors are typically placed near the opening of the casing. These current collectors are welded to the side wall of the casing and the tabs of the electrode assembly, thereby achieving electrical connection between the casing and the electrode assembly. This structure is relatively complex, and the associated assembly process is also complex, involving numerous welding steps. Utility Model Content

[0003] This utility model provides a secondary battery, a battery pack, and an electronic device to improve the technical problems of complex assembly processes and numerous welding processes between electrode components and the casing during the production of secondary batteries.

[0004] This utility model provides a secondary battery, which includes: a shell, an electrode assembly, and a cover plate; the shell includes a surrounding sidewall with an opening at one end; the electrode assembly is installed inside the shell and includes a first electrode, a second electrode, and a separator layered and wound to form a wound structure, the first electrode includes a first current collector and a first active material, the first current collector includes a first coated area coated with the first active material and a first empty foil without active material, and multiple first empty foils are stacked and gathered to form a lead-out portion; the cover plate covers and seals the opening, and the cover plate and the sidewall are connected by solder; the lead-out portion is connected to the cover plate by solder, and / or the lead-out portion is connected to the sidewall by solder.

[0005] In one embodiment of the present invention, the lead-out portion includes a plurality of sub-lead-out portions arranged at intervals along the circumference of the electrode assembly, and each sub-lead-out portion is welded to the inner wall of the cover plate and the side wall.

[0006] In one embodiment of the present invention, the sidewall includes a first stepped portion disposed at the opening, the first stepped portion includes a first mating surface facing the cover plate, the lead-out portion includes a first welding portion, the first welding portion is clamped between the cover plate and the first mating surface, and the first welding portion, the cover plate and the first stepped portion are connected by a solder joint.

[0007] In one embodiment of the present invention, the lead-out portion further includes a first transition portion and a first gathering portion. The first gathering portion is formed by stacking and gathering multiple first empty foil sheets that are simultaneously bent relative to each other from the radially outer and radially inner sides. The first transition portion connects the first welding portion and the first gathering portion. A third step portion is provided on the outer periphery of the cover plate facing the electrode assembly. The third step portion includes a positioning slope facing the side wall. The first transition portion bends relative to the first gathering portion toward the side wall to form a first bending portion. The first transition portion is at least partially accommodated in the third step portion along the height direction of the cover plate. The first bending portion of the first transition portion abuts against the positioning slope.

[0008] In one embodiment of the present invention, the sidewall includes a second stepped portion disposed at the opening, the second stepped portion includes a second mating surface, the lead-out portion includes a second welding portion, the bottom end of the second welding portion abuts against the second mating surface and extends along the height direction of the sidewall, the second welding portion includes a first end face connected to the cover plate and a first side face connected to the inner surface of the second stepped portion, the first end face, the first side face, the outer peripheral surface of the cover plate and the inner surface of the second stepped portion are connected by a solder joint; the lead-out portion also includes a second transition portion and a second gathering portion, the second gathering portion is formed by stacking and gathering multiple first empty foil sheets that are bent simultaneously from the radial outer side and the radial inner side, or by stacking and gathering multiple first empty foil sheets that are bent from the radial inner side to the radial outer side, the second transition portion connects the second welding portion and the second gathering portion, the second welding portion bends toward the cover plate relative to the second transition portion and forms a second bending portion.

[0009] In one embodiment of the present invention, the lead-out portion includes a third welding portion, which is sandwiched between the inner wall of the sidewall and the outer peripheral surface of the cover plate. The third welding portion, the cover plate, and the inner wall of the sidewall are connected by a solder joint. The lead-out portion also includes a third transition portion and a third gathering portion. The third gathering portion is formed by stacking and gathering multiple first empty foil sheets bent from the radial inner side to the radial outer side. The third transition portion connects the third welding portion and the third gathering portion.

[0010] In one embodiment of the present invention, the lead-out part includes an ultrasonic welding part formed by gathering and ultrasonically welding a first empty foil sheet, the thickness of the ultrasonic welding part being greater than or equal to 0.1 mm, and the ultrasonic welding part being welded to the side wall and the cover plate.

[0011] In one embodiment of the present invention, the lead-out part includes an ultrasonic welding part formed by stacking a plurality of first empty foil sheets and at least one welding protection sheet. The welding protection sheet is disposed on one or both sides of the plurality of first empty foil sheets. The thickness of the ultrasonic welding part is greater than or equal to 0.1 mm. The ultrasonic welding part is welded to the side wall and the cover plate.

[0012] This utility model also provides a battery pack, which includes any of the above-mentioned secondary batteries.

[0013] This invention also provides an electronic device that includes the aforementioned battery pack.

[0014] The beneficial effects of this utility model are as follows: The secondary battery proposed in this utility model simplifies the structure by directly welding the lead-out portion to the shell and cover plate by gathering multiple first empty foil pieces of the electrode assembly together to form the lead-out portion. This replaces the method of connecting the electrode assembly and the shell through the current collector component. Furthermore, it enables simultaneous welding of the lead-out portion, shell, and cover plate by laser welding, replacing the three welding processes of first welding the electrode assembly and current collector component, then welding the current collector component and cover plate, and finally welding the cover plate and side wall. This reduces the number of welding processes, improves assembly efficiency, and addresses the technical problems of complex assembly processes and numerous welding processes between the electrode assembly and the shell in the secondary battery production process. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0016] In the attached diagram:

[0017] Figure 1 This is a schematic diagram of the structure of a secondary battery provided in an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of an electrode assembly provided in one embodiment of the present invention;

[0019] Figure 3 Provided in one embodiment of this utility model Figure 1 A magnified view of a section at point A in the middle;

[0020] Figure 4 This is provided in one embodiment of the present utility model. Figure 3 A magnified view of a section at point B in the middle;

[0021] Figure 5 Provided for an embodiment of this utility model Figure 4 A schematic diagram after welding;

[0022] Figure 6 This is a partially enlarged schematic diagram of the electrode assembly provided in one embodiment of the present invention;

[0023] Figure 7 Provided in one embodiment of this utility model Figure 1 A magnified view of a section at point A in the middle;

[0024] Figure 8 This is provided in one embodiment of the present utility model. Figure 7A magnified view of a section at point C;

[0025] Figure 9 Provided for an embodiment of this utility model Figure 8 A schematic diagram after welding;

[0026] Figure 10 This is a partially enlarged schematic diagram of the electrode assembly provided in one embodiment of the present invention;

[0027] Figure 11 Provided in one embodiment of this utility model Figure 1 A magnified view of a section at point A in the middle;

[0028] Figure 12 This is provided in one embodiment of the present utility model. Figure 11 A magnified view of a section at point D;

[0029] Figure 13 Provided for an embodiment of this utility model Figure 12 A schematic diagram after welding;

[0030] Figure 14 This is a partially enlarged schematic diagram of the electrode assembly provided in one embodiment of the present invention;

[0031] Figure 15 This is a partially enlarged schematic diagram of the electrode assembly provided in one embodiment of the present invention;

[0032] Figure 16 This is provided in one embodiment of the present utility model. Figure 15 A magnified view of a section at point E in the middle;

[0033] Figure 17 A partially enlarged schematic diagram of an electrode assembly provided in an embodiment of the present invention;

[0034] Figure 18 Provided in one embodiment of this utility model Figure 17 A magnified view of a section at point F in the middle;

[0035] Figure 19 This is a schematic diagram of the structure of an electrode assembly provided in one embodiment of the present invention;

[0036] Figure 20 This is a schematic diagram of the structure of an electronic device provided in one embodiment of the present invention.

[0037] The attached figures are labeled as follows:

[0038] 1. Electronic device; 10. Battery pack; 11. Working part; 101. Housing; 102. Housing cover; 100. Secondary battery; 110. Shell; 111. End wall; 112. Side wall; 113. Opening; 114. First step; 1141. First mating surface; 115. Second step; 1151. Second mating surface; 120. Electrode assembly; 121. First electrode; 1211. Negative current collector; 1212. First coating area; 1213. First empty foil; 122. Separator; 123. Second electrode; 1231. Positive current collector; 1232. Second coating area; 1233. Second empty foil; 124. Lead-out part; 1241. First solder 1242, First transition section; 12421, First bending section; 1243, First gathering section; 1244, Second welding section; 12441, Bottom end; 12442, First side surface; 12443, First end face; 1245, Second transition section; 1246, Second gathering section; 1247, Third welding section; 1248, Third transition section; 1249, Third gathering section; 125, Electrode lug; 126, Sub-lead-out section; 130, Cover plate; 131, Third step section; 1311, Positioning bevel; 141, First weld mark; 142, Second weld mark; 143, Third weld mark; 150, Electrode post; 160, Ultrasonic welding section; 161, Welding protection plate. Detailed Implementation

[0039] 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. 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. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0040] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0041] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the present invention.

[0042] Please see Figures 1 to 20 This utility model provides a secondary battery 100, a battery pack 10, and an electronic device 1. By gathering multiple first empty foils 1213 of the electrode assembly 120 to form a lead-out portion 124, the lead-out portion 124 is directly welded to the housing 110 and the cover plate 130, replacing the method of connecting through current collector components. This simplifies the structure, reduces the number of welding steps, and improves the technical problem of complex assembly process and numerous welding steps between the electrode assembly 120 and the housing 110 during the production of the secondary battery 100.

[0043] Please see Figure 1 This utility model provides a secondary battery 100, which includes a housing 110, an electrode assembly 120, a cover plate 130, and a terminal post 150.

[0044] Please see Figure 1 The housing 110 includes an end wall 111 and a side wall 112 surrounding the end wall 111. 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 it can follow any other closed-loop contour that matches the end wall 111. In this embodiment, the outer edge of the end wall 111 is circular, and the side wall 112 is cylindrical, surrounding the outer edge of the end wall 111, with a circular opening 113 formed at the end of the side wall 112 facing away from the end wall 111. A receiving cavity is formed within the housing 110 formed by the end wall 111 and the side wall 112 to accommodate the electrode assembly 120, electrolyte, and other necessary battery components.

[0045] Please see Figures 1 to 2 The electrode assembly 120 is housed within the casing 110 and is a component in the secondary battery 100 where electrochemical reactions occur. The casing 110 may contain one or more electrode assemblies 120. The electrode assembly 120 includes a wound structure formed by stacking and winding a first electrode 121, a second electrode 123, and a separator 122. The first electrode 121 and the second electrode 123 have opposite polarities. In some embodiments, the first electrode 121 is a positive electrode and the second electrode 123 is a negative electrode; in other embodiments, the first electrode 121 is a negative electrode and the second electrode 123 is a positive electrode.

[0046] Please see Figures 1 to 2The first electrode 121 includes a first current collector and a first active material. In this embodiment, the first electrode 121 is a negative electrode, so the first current collector is a negative current collector 1211, and the first active material is a negative active material coated on the surface of the negative current collector 1211. The negative current collector 1211 includes a first coating area 1212 coated with active material and an empty foil without active material coating. To distinguish it from the empty foil on the second electrode 123, the empty foil of the first current collector is called the first empty foil 1213. The first empty foil 1213 is located at the end of the first electrode 121, and the first empty foil 1213 extends out of the diaphragm 122 along the winding axis of the electrode assembly 120. Multiple first empty foils 1213 are stacked and gathered to form a lead-out portion 124. It should be noted that the lead-out portion 124 can be formed by stacking and gathering all the first empty foils 1213, or it can be formed by stacking and gathering some of the empty foils; there is no limitation on this. In one example, the first empty foil 1213 that does not form the lead-out portion 124 and is located radially inside the lead-out portion 124 can be stacked on top of each other, and the first empty foil 1213 located radially outside can overlap the root of the lead-out portion 124, such as the first gathering portion 1243.

[0047] Please see Figures 1 to 2 The second electrode 123 is a positive electrode. Specifically, the second electrode 123 includes a positive current collector 1231 and a positive active material. The positive active material is coated on the surface of the positive current collector 1231. The positive current collector 1231 includes a second coating area 1232 coated with active material and a second empty foil 1233 uncoated with active material. The second empty foil 1233 is located at the end of the second electrode 123. The other end of the second empty foil 1233 extends out of the diaphragm 122 along the winding axis of the electrode assembly 120 and is bent toward the winding axis to form an electrode tab 125.

[0048] Please see Figures 1 to 2A separator 122 is disposed between the first electrode 121 and the second electrode 123 to isolate the positive electrode active material layer and the negative electrode active material layer. Taking a lithium-ion secondary battery 100 as an example, the positive electrode current collector 1231 can be made of aluminum, and the positive electrode active material layer includes positive electrode active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode current collector 1211 can be made of copper, and the negative electrode active material layer includes negative electrode 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 120, an insulating film can also be wrapped around the electrode assembly 120. The insulating film can be synthesized from PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC), or other polymer materials.

[0049] Please see Figure 1 and Figure 2 Furthermore, if the lead-out portion 124 faces the end wall 111 or the opening 113, then the tab 125 faces the other end of the housing 110. In this embodiment, the tab 125 faces the end wall 111 and is electrically connected to the terminal post 150, making the terminal post 150 positively charged. The lead-out portion 124 faces the opening 113, and the housing 110 is electrically connected to the lead-out portion 124, thus becoming negatively charged. However, in another embodiment, the lead-out portion 124 can be connected to the terminal post 150, and the tab 125 can be connected to the housing 110.

[0050] Please see Figure 1 The electrode post 150 is fixed to the end wall 111 and electrically connected to the electrode assembly 120. Specifically, the end wall 111 is provided with an electrode post hole, and the electrode post 150 is installed through the electrode post hole and insulated from the end wall 111. The end of the electrode post 150 facing the electrode assembly 120 passes through the end wall 111 and is directly electrically connected to the tab 125 or indirectly connected via a converter. The structure of the electrode post 150 can be any suitable form that can pass through the end wall 111 and be electrically connected to the tab 125 of the electrode assembly 120. For example, the cross-section can be circular, square, prismatic, or an irregular contour that can achieve stable conductivity. The shape of the electrode post hole corresponds to the shape of the electrode post 150. In this embodiment, the cross-section of the electrode post 150 is circular.

[0051] Please see Figures 3 to 14The cover plate 130 covers and seals the opening 113. The cover plate 130 and the side wall 112 are connected by a weld mark. This weld mark can be formed by welding the cover plate 130 and the side wall 112 using a laser welding process, specifically by seam welding, through welding, etc. In some embodiments, the end faces of the cover plate 130 and the side wall 112 are welded together. In this embodiment, the outer peripheral surface of the cover plate 130 and the inner wall of the side wall 112 are welded together. The lead-out portion 124 is arranged around the central axis of the electrode assembly 120, and the lead-out portion 124 is connected to the cover plate 130 by the same weld mark, and / or the lead-out portion 124 is connected to the side wall 112 by the same weld mark. Welding the lead-out portion 124 of the electrode assembly 120 directly to the housing 110 and the cover plate 130 by the same weld mark replaces the method of connecting the electrode assembly 120 and the housing 110 through a current collector, simplifying the structure. Laser welding can be used to simultaneously weld the lead-out part 124, side wall 112 and cover plate 130, replacing the three welding processes of first welding the electrode assembly 120 and current collector, then welding the current collector and cover plate 130, and finally welding the cover plate 130 and side wall 112. This reduces the number of welding processes and improves assembly efficiency.

[0052] The shape of the lead-out portion 124 is not limited; in one embodiment, please refer to [reference needed]. Figure 3 , Figure 7 and Figure 11 The lead-out portion 124 has a surrounding closed structure, which helps to enhance the current-carrying capacity of the lead-out portion 124 and reduce the internal resistance of the battery. In another embodiment, please refer to... Figure 6 , Figure 10 and Figure 14 The lead-out portion 124 includes a plurality of sub-lead-out portions 126 spaced apart along the circumference of the electrode assembly 120. Each sub-lead-out portion 126 is welded to the cover plate 130 and the inner wall of the side wall 112. The number of sub-lead-out portions 126 is not limited; for example, it can be 4, 6, 8, or more. In this embodiment, there are 4 sub-lead-out portions 126. Each sub-lead-out portion 126 bears stress independently, which can reduce the risk of overall welding failure. Each sub-lead-out portion 126 is welded and fixed independently, which reduces the difficulty of welding connection and further improves the reliability of welding connection.

[0053] There are various ways in which the lead-out portion 124, cover plate 130, and side wall 112 can be fitted together. This can be achieved by designing the structure of the lead-out portion 124, cover plate 130, and side wall 112. Three embodiments are described below for illustrative purposes. For distinction and ease of understanding, these embodiments are respectively named the first solder mark 141, the second solder mark 142, and the third solder mark 143. It should be noted that the lead-out portion 124 in the following embodiments can be a closed, encircling type or a type with multiple sub-lead-out portions 126 spaced around it. These two forms of the lead-out portion 124 will not be described separately.

[0054] Please see Figures 3 to 6 In one embodiment of this utility model, the sidewall 112 includes a first stepped portion 114 disposed in the opening 113. The first stepped portion 114 includes a first mating surface 1141 facing the cover plate 130. The lead-out portion 124 includes a first welding portion 1241. It should be noted that the first welding portion 1241 refers to the portion of the lead-out portion 124 used for welding connection. The first welding portion 1241 is clamped between the cover plate 130 and the first mating surface 1141, and the outer peripheral surface of the first welding portion 1241 and the outer peripheral surface of the cover plate 130 are both adapted to the inner surface of the first stepped portion 114. The above-mentioned mating relationship facilitates the positioning of the first welding portion 1241 and the cover plate 130, and facilitates the welding and fixing of the lead-out portion 124, the cover plate 130 and the sidewall 112. The first welded portion 1241, the cover plate 130, and the first stepped portion 114 are connected by a first weld mark 141, that is, the first welded portion 1241, the cover plate 130, and the first stepped portion 114 are welded and fixed by a single laser welding operation. Please refer to [link / reference]. Figure 5 This welding method simplifies the welding process and improves welding efficiency. Furthermore, the reduction in welding steps significantly reduces the generation of metal chips and slag inside the housing 110, lowering the risk of foreign objects inside. Simultaneously, saving an internal structural component not only reduces production costs but also lightens the internal weight, which is beneficial for improving the mass energy density of the secondary battery 100. In addition, since the laser welding is located above the cover plate 130 and uses a seam welding method, with the first mating surface 1141 facing the cover plate 130, it can effectively block heat transfer into the housing 110, thereby reducing the thermal impact of welding heat on the electrode assembly 120.

[0055] Please see Figures 4 to 5In one embodiment of this utility model, the lead-out portion 124 further includes a first transition portion 1242 and a first gathering portion 1243. The first gathering portion 1243 is formed by simultaneously gathering stacked empty foil sheets from the radially outer and radially inner sides. Specifically, the first gathering portion 1243 is formed by gradually gathering stacked first empty foil sheets 1213 from their roots. The first gathering portion 1243 gradually shrinks from the roots of the empty foil sheets until it is compacted, and the compacted portion is fixed by ultrasonic flat welding to form an ultrasonic welding portion 160. The portion located at the free end of the ultrasonic welding portion 160 and welded to the cover plate 130 and the side wall 112 is defined as the first welding portion 1241. A first transition portion 1242 is also provided between the first welding portion 1241 and the first gathering portion 1243. The shape of the first transition portion 1242 is not limited and is used to adjust the position and shape of the first welding portion 1241 to meet different forms of mating. Furthermore, the way in which the stacked first empty foil 1213 simultaneously retracts from the radially outer and radially inner sides can create a distance between the formed first retracted portion 1243 and the sidewall 112, providing a space for the first welded portion 1241 to form a shape in which the first welded portion 1241 extends radially along the cover plate 130.

[0056] It should be noted that in some embodiments, the length of the first empty foil 1213 extending out of the diaphragm 122 is uniform. When the first empty foil 1213 is simultaneously retracted from the radially outer and radially inner sides, the length of the first empty foil 1213 located near the radially outer edge and the mirror inner edge is insufficient. The insufficiently long first empty foil 1213 is bent and overlapped on the outside of the first retracted portion 1243. In other embodiments, the length of the first empty foil 1213 extending out of the diaphragm 122 is not uniform, so that the length and thickness of the ultrasonically welded portion 160 formed after retraction are uniform.

[0057] Please see Figure 4In one embodiment of this utility model, a third step portion 131 is provided on the outer periphery of the cover plate 130 facing the electrode assembly 120. The third step portion 131 includes a positioning inclined surface 1311 facing the side wall 112. A first transition portion 1242 bends relative to the first convergent portion 1243 toward the side wall 112 to form a first bent portion 12421. The first transition portion 1242 is at least partially accommodated in the third step portion 131 along the height direction of the cover plate 130. The first bent portion 12421 of the first transition portion 1242 abuts against the positioning inclined surface 1311. The provision of the first transition portion 1242 realizes the fixation of the first welding portion 1241 between the first mating surface 1141 and the cover plate 130. Preferably, since the outer surface of the first bent portion 12421 is curved, in order to improve the positioning effect of the positioning inclined surface 1311 on the first bent portion 12421, the positioning inclined surface 1311 is set as an inclined surface. In addition, the positioning ramp 1311 helps to improve the coaxiality of the cover plate 130 and the housing 110, and helps to push the first transition part 1242 to move radially outward, thereby pushing the first welded part 1241 into place.

[0058] Please see Figures 7 to 10 In one embodiment of the present invention, the sidewall 112 includes a second stepped portion 115 disposed in the opening 113. The second stepped portion 115 includes a second mating surface 1151, and the lead-out portion 124 includes a second welding portion 1244. The bottom end 12441 of the second welding portion 1244 abuts against the second mating surface 1151 and extends along the height direction of the sidewall 112. The second welding portion 1244 includes a first end face 12443 connected to the cover plate 130 and a first side face 12442 connected to the inner surface of the second stepped portion 115. The second mating surface 1151 can play a positioning role for the second welding portion 1244 and also facilitates the first end face 12443 of the second welding portion 1244 to abut against the cover plate 130, thereby improving the welding quality. The first end face 12443, the first side face 12442, the outer peripheral surface of the cover plate 130, and the inner surface of the second stepped portion 115 are connected by a second weld mark 142. That is, the first end face 12443, the first side face 12442, the outer peripheral surface of the cover plate 130, and the inner surface of the second stepped portion 115 are welded and fixed by a single laser welding. Please refer to [link / reference]. Figure 9 This welding fixing method also simplifies the welding process and improves welding efficiency. Simultaneously, this arrangement increases the contact area between the first welding part 1241 and the side wall 112, improving the welding reliability of the lead-out part 124 and the side wall 112, and further reducing the probability of electrical connection failure between the electrode assembly 120 and the housing 110 during assembly. Furthermore, since the laser welding position is located above the cover plate 130 and uses a seam welding method, the second mating surface 1151 can also block heat transfer into the housing 110, thereby reducing the thermal impact of welding heat on the electrode assembly 120.

[0059] Please see Figures 8 to 9 In one embodiment of this utility model, to achieve the above-mentioned cooperation method, the lead-out portion 124 further includes a second transition portion 1245 and a second gathering portion 1246. The formation methods of the second gathering portion 1246, the second welding portion 1244, and the second transition portion 1245 are the same as those of the first gathering portion 1243, the first welding portion 1241, and the first transition portion 1242, and will not be repeated here. The difference in this embodiment is that the second gathering portion 1246 is formed by simultaneously gathering the stacked first empty foil sheets 1213 from the radially outer side and the radially inner side, or by gathering from the radially inner side to the radially outer side (not shown in the figure). The second gathering portion 1246 formed in both of these ways can provide a receiving space for the second welding portion 1244. Similarly, when the length of the first empty foil sheet 1213 that is far from the second gathering portion 1246 is insufficient, it is overlapped on the outside of the second gathering portion 1246. The second transition portion 1245 connects the second welding portion 1244 and the second gathering portion 1246. The shape of the second transition portion 1245 is not limited and is used to adjust the position and shape of the second welding portion 1244 to meet different forms of mating. For example, in this embodiment, the second welding portion 1244 is bent toward the cover plate 130 relative to the second transition portion 1245 to form the bottom end 12441 of the second welding portion 1244. Considering that the bottom end 12441 of the second welding portion 1244 has a curved outer surface, in order to increase the contact area between the second mating surface 1151 and the bottom end 12441, the second mating surface 1151 is set as a curved surface adapted to the bottom end 12441.

[0060] Please see Figures 11 to 14 In one embodiment of this utility model, the lead-out portion 124 includes a third welding portion 1247, which is sandwiched between the inner wall of the side wall 112 and the outer peripheral surface of the cover plate 130. Specifically, along the radial direction of the cover plate 130 from the inside to the outside, the components are the cover plate 130, the third welding portion 1247, and the side wall 112. The third welding portion 1247, the cover plate 130, and the inner wall of the side wall 112 are connected by a third weld mark 143, meaning that the third welding portion 1247, the cover plate 130, and the side wall 112 are welded and fixed in one laser welding operation. Please refer to [link to relevant documentation]. Figure 13 This welding fixing method also simplifies the welding process. In addition, the third weld mark 143 formed by this setting is smaller in size, reducing welding energy consumption.

[0061] Please see Figures 13 to 14In one embodiment of this utility model, the lead-out portion 124 further includes a third transition portion 1248 and a third gathering portion 1249. The formation of the third gathering portion 1249, the third welding portion 1247, and the third transition portion 1248 is the same as that of the first gathering portion 1243, the first welding portion 1241, and the first transition portion 1242, and will not be described again. The difference in this embodiment is that the third gathering portion 1249 is formed by gathering stacked first empty foil sheets 1213 from the radially inner side to the radially outer side, so that the third welding portion 1247 is closer to the side wall 112. Similarly, when the length of the first empty foil sheet 1213 that is far from the third gathering portion 1249 is insufficient, it is overlapped on the outside of the second gathering portion 1246. The third transition portion 1248 connects the third welding portion 1247 and the third gathering portion 1249. The shape of the third transition portion 1248 is not limited and is used to adjust the position and shape of the third welding portion 1247 to meet different forms of mating. For example, in this embodiment, both the third transition portion 1248 and the third welding portion 1247 extend along the height direction of the side wall 112 to limit the third welding portion 1247 to be located between the inner wall of the side wall 112 and the outer peripheral surface of the cover plate 130.

[0062] Please see Figures 3 to 14 In one embodiment of this utility model, the lead-out portion 124 includes an ultrasonically welded portion 160 formed by gathering and fixing a first empty foil sheet 1213 using ultrasonic welding. Specifically, the stacked first empty foil sheet 1213 gradually gathers and shrinks from its root until it is compacted, and the compacted portion is fixed by ultrasonic flat welding to form the ultrasonically welded portion 160. The thickness of the ultrasonically welded portion 160 is greater than or equal to 0.1 mm. Figure 6 As shown in Figure a, the ultrasonic welded part 160 with a thickness of 0.1 mm or more has sufficient strength to meet the strength requirements of positioning, assembly and welding processes. Therefore, the free end of the ultrasonic welded part 160 can be directly welded to the side wall 112 and the cover plate 130.

[0063] Please see Figures 15 to 18 In one embodiment of the present invention, in order to improve the strength of the ultrasonic welding part 160, a welding protection sheet 161 is provided on at least one side of the multiple stacked first empty foil sheets 1213 along the thickness direction. In one embodiment, the welding protection sheet 161 is provided only on one side of the multiple first empty foil sheets 1213, such as... Figure 18 As shown, in some other embodiments, welding protective sheets 161 are provided on both sides of the plurality of first empty foil sheets 1213, such as... Figure 16 As shown. Further, the sum of the thicknesses of the plurality of first empty foils 1213 and the welding protective sheet 161 satisfies a thickness greater than or equal to 0.1 mm, and the sum of the thicknesses of the plurality of first empty foils 1213 and the welding protective sheet 161 is in... Figure 16 and Figure 18The part marked with 'b' is a welded part with a weld protection plate 161. This welded part has sufficient strength to meet the requirements of positioning, assembly, and welding processes, ensuring the welded connection between the free end of the ultrasonic welded part 160 and the side wall 112 and the cover plate 130. Particularly in some embodiments, the thickness of the stacked plurality of first empty foil sheets 1213 is less than 0.1 mm, and the total thickness of the stacked plurality of first empty foil sheets 1213 is within... Figure 16 and Figure 18 The part marked with 'a' needs to be equipped with a welding protective sheet 161 to supplement the thickness, so as to improve the strength of the welded part, thereby improving the welding quality and welding efficiency.

[0064] Please see Figure 19 This utility model also provides a battery pack 10, which includes the secondary battery 100 described above. In one embodiment of the battery pack 10, the battery pack 10 includes a housing 101, a cover 102, and multiple secondary batteries 100. The multiple secondary batteries 100 are placed in the housing 101 and are connected in series or parallel, or a combination of series and parallel connections. The cover 102 covers the housing 101 to protect the multiple secondary batteries 100. It should be noted that, in addition to the secondary battery 100 of this utility model, the battery pack 10 may also include a battery pack thermal management system, circuit board, etc. The battery pack 10 can be a battery module, a battery pack, an energy storage cabinet, etc.; these will not be described in detail here.

[0065] Please see Figure 20 This utility model also provides an electronic device 1, which includes the aforementioned battery pack 10. A working part 11 is electrically connected to the battery pack 10 to obtain electrical power. As an example, the electronic device 1 is a vehicle, which 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 11 is the vehicle body, and the battery pack 10 is located at the bottom of the vehicle body, providing electrical power for the vehicle's operation or the operation of its internal electrical components. However, in other embodiments, the electronic device 1 can also be a mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working part 11 can be a unit component capable of obtaining electrical power from the battery pack 10 and performing corresponding work, such as a fan blade rotation unit or a vacuum cleaner 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 1.

[0066] This invention proposes a secondary battery that simplifies the structure by directly welding the electrode assembly's tabs to the casing and cover, replacing the previous method of connecting the tabs and casing via a current collector. Furthermore, it allows for simultaneous welding of the tabs, casing, and cover using laser welding, replacing the previous three-step welding process of first welding the tabs and current collector, then the current collector and cover, and finally the cover and sidewall. This reduces the number of welding steps and improves assembly efficiency.

[0067] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter 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 should still be covered by the claims of this utility model.

Claims

1. A secondary battery characterized by comprising: include: The housing includes surrounding sidewalls, one end of which has an opening; An electrode assembly is installed inside the housing. The electrode assembly includes a first electrode, a second electrode, and a winding structure formed by stacking and winding a diaphragm. The first electrode includes a first current collector and a first active material. The first current collector includes a first coating area coated with the first active material and a first empty foil uncoated with the active material. A plurality of the first empty foils are stacked and gathered to form an outlet. A cover plate, which seals the opening, is connected to the sidewall by a weld. The lead-out portion is connected to the cover plate by the solder joint, and / or the lead-out portion is connected to the side wall by the solder joint.

2. The secondary battery according to claim 1, characterized by The lead-out portion includes a plurality of sub-lead-out portions arranged at intervals along the circumference of the electrode assembly, and each of the sub-lead-out portions is welded to the inner wall of the cover plate and the side wall.

3. The secondary battery according to claim 1 or 2, characterized by The sidewall includes a first stepped portion disposed at the opening, the first stepped portion including a first mating surface facing the cover plate, the lead-out portion including a first welded portion, the first welded portion being clamped between the cover plate and the first mating surface, and the first welded portion, the cover plate and the first stepped portion being connected by the weld mark.

4. The secondary battery according to claim 3, characterized by The lead-out portion further includes a first transition portion and a first gathering portion. The first gathering portion is formed by stacking and gathering multiple first empty foil sheets that are simultaneously bent relative to each other from the radially outer and radially inner sides. The first transition portion connects the first welding portion and the first gathering portion. The cover plate has a third step portion on the outer periphery facing the electrode assembly. The third step portion includes a positioning slope facing the side wall. The first transition portion bends toward the side wall relative to the first convergence portion to form a first bend portion. The first transition portion is at least partially accommodated in the third step portion along the height direction of the cover plate. The first bend portion of the first transition portion abuts against the positioning slope.

5. The secondary battery according to claim 1 or 2, characterized by The sidewall includes a second stepped portion disposed at the opening, the second stepped portion includes a second mating surface, the lead-out portion includes a second welded portion, the bottom end of the second welded portion abuts against the second mating surface and extends along the height direction of the sidewall, the second welded portion includes a first end face connected to the cover plate and a first side face connected to the inner surface of the second stepped portion, the first end face, the first side face, the outer peripheral surface of the cover plate and the inner surface of the second stepped portion are connected by the weld mark; The lead-out portion further includes a second transition portion and a second gathering portion. The second gathering portion is formed by stacking and gathering multiple first empty foil sheets that are simultaneously bent relative to each other from the radially outer and radially inner sides, or by stacking and gathering multiple first empty foil sheets that are bent from the radially inner side to the radially outer side. The second transition portion connects the second welding portion and the second gathering portion. The second welding portion bends relative to the second transition portion toward the cover plate to form a second bending portion.

6. The secondary battery according to claim 1 or 2, characterized by The lead-out portion includes a third welding portion, which is sandwiched between the inner wall of the side wall and the outer peripheral surface of the cover plate. The third welding portion, the cover plate, and the inner wall of the side wall are connected by the weld mark. The lead-out portion further includes a third transition portion and a third gathering portion. The third gathering portion is formed by stacking and gathering multiple first empty foil sheets that are bent from the radial inside to the radial outside. The third transition portion connects the third welding portion and the third gathering portion.

7. The secondary battery according to claim 1 or 2, characterized by The lead-out section includes an ultrasonically welded section formed by gathering and ultrasonically welding the first empty foil sheet. The thickness of the ultrasonically welded section is greater than or equal to 0.1 mm. The ultrasonically welded section is welded to the side wall and the cover plate.

8. The secondary battery according to claim 1 or 2, characterized by The lead-out section includes an ultrasonic welding section formed by stacking multiple first empty foil sheets and at least one welding protective sheet. The welding protective sheet is disposed on one or both sides of the multiple first empty foil sheets. The thickness of the ultrasonic welding section is greater than or equal to 0.1 mm. The ultrasonic welding section is welded to the side wall and the cover plate.

9. A battery pack characterized by comprising: The secondary battery includes any one of claims 1 to 8.

10. An electronic device, comprising: Includes the battery pack as described in claim 9.

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