Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a kind of secondary battery, battery pack and electronic device;The secondary battery includes: cover plate, shell, electrode assembly and current collecting member, shell includes side wall, side wall is formed at least one opening around in circumference, cover plate blocks one opening;Electrode assembly is contained in shell, and one side of electrode assembly has tab;Current collecting member includes first connecting part and second connecting part, second connecting part is welded with tab, and first connecting part surrounds the outer periphery of second connecting part, cover plate, first connecting part and side wall are connected by welding mark;Current collecting member further includes buffer part, the first end of first connecting part located in radial inner side, the second end of second connecting part located in radial outer side, buffer part connects first end and second end, the length of buffer part is L, the distance of first end to second end along the axial direction of shell is W, L>W>0, can improve the technical problem that secondary battery is subjected to vibration impact and easily lead to the de-soldering between current collecting member and cover plate, shell.

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 secondary batteries, a current collector is usually placed near the opening of the casing, with the outer periphery of the current collector connected to the side wall of the casing and the edge of the cover plate, and the current collector is welded to the tabs of the electrode assembly on the radial inner side.

[0003] The existing design of the tabs and cover plates has a large space in the axial direction. In the operating conditions of cylindrical batteries, the current collector is easily subjected to Z-direction (i.e. axial) vibration and impact, which may cause the current collector to desolder from the cover plate and the casing, directly affecting the battery's performance, service life and safety. Utility Model Content

[0004] This utility model provides a secondary battery, a battery pack, and an electronic device to improve the technical problem that the current collector is prone to detachment from the cover plate and the shell when the secondary battery is subjected to vibration and impact.

[0005] This utility model provides a secondary battery, which includes a cover plate, a shell, an electrode assembly, and a current collector. The shell includes a side wall, which forms at least one opening in the circumferential direction. The cover plate seals at least one opening. The electrode assembly is housed in the shell, and the electrode assembly has a tab on the side facing the opening. The current collector is disposed on the side of the electrode assembly facing the cover plate. The current collector includes a first connecting part and a second connecting part. The second connecting part is welded to the tab. The first connecting part is disposed around the outer periphery of the second connecting part. The cover plate, the first connecting part, and the side wall are connected by a solder joint. The current collector also includes a buffer part. On a cross section passing through the axis of the current collector and the first connecting part, the end of the first connecting part located radially inward is the first end, and the end of the second connecting part located radially outward is the second end. The buffer part connects the first end and the second end. The length of the buffer part is L, and the distance from the first end to the second end along the axial direction of the shell is W, where L > W > 0.

[0006] In one embodiment of the present invention, the sidewall includes a first stepped portion disposed at one end near the cover plate. The first stepped portion includes a first mating surface facing the cover plate. A first connecting portion is clamped between the cover plate and the first mating surface. The first connecting portion, the cover plate, and the first stepped portion are connected by welding. Along the axial direction of the housing, the first end is closer to the cover plate than the second end. The buffer portion includes a first inclined wall disposed between the first end and the second end. The angle between the first inclined wall and the plane containing the second connecting portion is α, where 90°<α≤135°.

[0007] In one embodiment of the present invention, a third step portion is provided on the outer periphery of the cover plate facing the electrode assembly. The third step portion includes a second inclined wall and a first annular surface connected to the radially outer end of the second inclined wall. The second inclined wall faces the first inclined wall and abuts against the first inclined wall. The first annular surface faces the first connecting portion and contacts the first connecting portion. The first annular surface, the first connecting portion and the side wall are connected by solder.

[0008] In one embodiment of the present invention, the buffer portion further includes a first recess connecting the first inclined wall and the second end, and a protrusion protruding from the second connecting portion is formed on the side of the first recess facing the electrode assembly.

[0009] In one embodiment of the present invention, along the radial direction of the shell, on the inner side of the first end, the buffer portion includes a seventh inclined wall, the seventh inclined wall connects the first end and the second end, and the angle between the seventh inclined wall and the plane where the second connecting portion is located is γ, wherein 45°≤γ<90°.

[0010] In one embodiment of the present invention, the sidewall includes a second stepped portion disposed at one end near the cover plate. The second stepped portion includes a second mating surface. The bottom end of the first connecting portion abuts against the second mating surface and extends in a direction away from the electrode assembly. The first connecting 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, and the outer peripheral surface of the cover plate are connected by solder. Along the axial direction of the housing, the first end is closer to the electrode assembly than the second end. A buffer portion connects the first end and the second end and forms a third inclined wall.

[0011] In one embodiment of the present invention, the first connecting portion extends in a direction away from the electrode assembly and is sandwiched between the inner wall of the sidewall and the outer peripheral surface of the cover plate. The first connecting portion, the cover plate, and the inner wall of the sidewall are connected by a solder mark. Along the axial direction of the housing, the first end is closer to the electrode assembly than the second end. The buffer portion connects the first end and the second end and forms a fourth inclined wall. The angle between the fourth inclined wall and the plane where the second connecting portion is located is β, where 15°<β≤45°.

[0012] In one embodiment of the present invention, the cover plate includes a second recess that is recessed toward the flow collecting member. A protrusion is formed on the side of the second recess facing the flow collecting member. The second recess includes a fifth inclined wall and a sixth inclined wall connected at their bottom ends. Along the radial direction of the cover plate, the fifth inclined wall is disposed outside the sixth inclined wall. The fifth inclined wall and the first inclined wall are similar in shape to each other.

[0013] This utility model also provides a battery pack, which includes any of the above-mentioned secondary batteries.

[0014] This invention also provides an electronic device that includes the aforementioned battery pack.

[0015] The beneficial effects of this utility model are as follows: This utility model proposes a secondary battery in which the current collector includes a second connecting portion and a first connecting portion. A buffer portion is provided between the second connecting portion and the first connecting portion. On a cross-section passing through the axis of the current collector and the first connecting portion, the buffer portion connects the first end and the second end. The length of the buffer portion is greater than the distance from the first end to the second end along the axial direction of the casing. This arrangement makes the buffer portion a redundant structure. Under vibration conditions, when the electrode assembly drives the current collector to undergo axial displacement inside the battery, the buffer portion can undergo local deformation under tensile force, thereby releasing stress and reducing the tensile force on the welded joints between the current collector and the casing and the welded joints between the current collector and the electrode tabs. Attached Figure Description

[0016] 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.

[0017] In the attached diagram: Figure 1 This is a schematic diagram of the structure of a secondary battery provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the electrode assembly provided in one embodiment of the present invention; Figure 3 Provided in one embodiment of this utility model Figure 1 A magnified view of a section at point A in the middle; 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; Figure 5 Provided in one embodiment of this utility model Figure 3 A magnified view of a section at point B in the middle; Figure 6 Provided in one embodiment of this utility model Figure 1 A magnified view of a section at point A in the middle; Figure 7 Provided in one embodiment of this utility model Figure 6 A magnified view of a section at point C; Figure 8 This is provided in one embodiment of the present utility model. Figure 1 A magnified view of a section at point A in the middle; Figure 9 Provided in one embodiment of this utility model Figure 8 A magnified view of a section at point D; Figure 10Provided in one embodiment of this utility model Figure 1 A magnified view of a section at point A in the middle; Figure 11 Provided in one embodiment of this utility model Figure 10 A magnified view of a section at point E in the middle; Figure 12 This is provided in one embodiment of the present utility model. Figure 10 A magnified view of a section at point E in the middle; Figure 13 Provided in one embodiment of this utility model Figure 1 A magnified view of a section at point A in the middle; Figure 14 Provided in one embodiment of this utility model Figure 13 A magnified view of a section at point F in the middle; Figure 15 Provided in one embodiment of this utility model Figure 1 A magnified view of a section at point A in the middle; Figure 16 This is provided in one embodiment of the present utility model. Figure 15 A magnified view of a section at point G in the middle; Figure 17 Provided in one embodiment of this utility model Figure 1 A magnified view of a section at point A in the middle; Figure 18 Provided in one embodiment of this utility model Figure 17 A magnified view of a section at point H in the middle; Figure 19 Provided in one embodiment of this utility model Figure 17 A magnified view of a section at point H in the middle; Figure 20 This is a partially enlarged view of the secondary battery after removing the cover plate, provided in one embodiment of the present invention. Figure 21 This is a partially enlarged view of the secondary battery after removing the cover plate, provided in one embodiment of the present invention. Figure 22 This is a partially enlarged view of the secondary battery after removing the cover plate, provided in one embodiment of the present invention. Figure 23 This is a partially enlarged view of the secondary battery after removing the cover plate, provided in one embodiment of the present invention. Figure 24 This is a schematic diagram of the structure of an electrode assembly provided in one embodiment of the present invention; Figure 25 This is a schematic diagram of the structure of an electronic device provided in one embodiment of the present invention.

[0018] The attached figures are labeled as follows: 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 coated area; 1213. First uncoated area; 122. Separator; 123. Second electrode; 1231. Positive current collector; 1232. Second coated area; 1233. Second uncoated area; 124. First tab; 125. Second tab; 130. Current collector component; 13 1. First connecting part; 1311. First end; 1312. First end face; 1313. First side face; 1314. Pin; 132. Second connecting part; 1321. Second end; 1322. Electrode connecting part; 133. Buffer part; 1331. First inclined wall; 1332. First recess; 1333. Third inclined wall; 1334. Fourth inclined wall; 1335. Seventh inclined wall; 1336. Clearance area; 134. Thickness reduction part; 140. Cover plate; 141. Third step part; 1411. Second inclined wall; 1412. First annular surface; 142. Second recess; 1421. Fifth inclined wall; 1422. Sixth inclined wall; 143. Third recess; 1431. Third connecting part; 150. Electrode post. Detailed Implementation

[0019] 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.

[0020] 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.

[0021] 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.

[0022] Please see Figures 1 to 25 An embodiment of the present invention provides a secondary battery 100, a battery pack 10, and an electronic device 1. A buffer portion 133 is provided between the second connecting portion 132 and the first connecting portion 131 in the secondary battery 100. The buffer portion 133 forms a redundant structure. Under vibration conditions, the electrode assembly 120 drives the current collector 130 to generate axial displacement inside the secondary battery 100. The buffer portion 133 can undergo local deformation under tensile force, thereby releasing stress and weakening the pull on the welded part between the current collector 130 and the shell 110.

[0023] Please see Figure 1 This utility model provides a secondary battery 100, which includes a cover plate 140, a shell 110, an electrode assembly 120, a current collector 130, and a terminal post 150.

[0024] Please see Figure 1 The housing 110 includes a sidewall 112 having at least one opening 113, and the sidewall 112 circumferentially surrounds a receiving cavity. The receiving cavity is used to receive the electrode assembly 120, electrolyte (not shown), and other components. The housing 110 is axially (e.g., Figure 1 The housing 110 (shown as O to O1) has at least one opening 113 at both ends, and a cover plate 140 seals at least one opening 113. In one embodiment, the housing 110 has openings 113 at opposite ends of the receiving cavity, and each opening 113 is closed by an end cap. In this embodiment, the housing 110 has an opening 113 at one end of the receiving cavity, and an end wall 111 integrally formed with the surrounding side wall 112 at the other end of the receiving cavity. The end wall 111 and the side wall 112 are integrally stamped or integrally cast. The circumference of the side wall 112 is not limited; it can be cylindrical, cuboid, or prismatic, or it can be along any other closed-loop contour that can match the end wall 111. In this embodiment, the outer edge of the end wall 111 is circular, and the side wall 112 is cylindrical and surrounds the outer edge of the end wall 111. A circular opening 113 is formed at the end of the side wall 112 opposite to the end wall 111, and the end cap closing the opening 113 is also circular. Please refer to [link to relevant documentation]. Figure 1 and Figure 2The electrode assembly 120 is disposed within the receiving cavity of the housing 110. The electrode assembly 120 is a component in the secondary battery 100 where an electrochemical reaction occurs. The housing 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.

[0025] Please see Figure 1 and Figure 2 In this embodiment, the first electrode 121 is a negative electrode. The first electrode 121 includes a negative current collector 1211 and a negative active material. The negative active material is coated on the surface of the negative current collector 1211. The negative current collector 1211 includes a first coated area 1212 coated with active material and a first uncoated area 1213 uncoated with active material. The first uncoated area 1213 is located at the end of the first electrode 121. The first uncoated area 1213 extends out of the diaphragm 122 along the winding axis of the electrode assembly 120 to form an electrode tab. In order to distinguish the electrode tab formed by the second electrode 123, the electrode tab located on the first electrode 121 is called the first electrode tab 124. The first electrode tab 124 is the corresponding negative electrode tab.

[0026] 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 coated area 1232 coated with active material and a second uncoated area 1233 uncoated with active material. The second uncoated area 1233 is located at the end of the second electrode 123. The other end of the second uncoated area 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 a second tab 125. The second tab 125 is the corresponding positive tab.

[0027] 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.

[0028] Please see Figure 1 and Figure 2 Furthermore, if the first tab 124 faces the end wall 111 or the opening 113, then the second tab 125 faces the other end of the housing 110. In this embodiment, the second tab 125 faces the end wall 111 and is electrically connected to the post 150, making the post 150 positively charged. The first tab 124 faces the opening 113, and the housing 110 is electrically connected to the first tab 124, thus becoming negatively charged. However, in another embodiment, the first tab 124 can be connected to the post 150, and the second tab 125 can be connected to the housing 110.

[0029] Please see Figure 1 The secondary battery 100 also includes a terminal post 150, which is fixed to the end wall 111 and electrically connected to the electrode assembly 120. Specifically, the end wall 111 is provided with a terminal post hole, and the terminal post 150 is installed through the terminal post hole and insulated from the end wall 111. The end of the terminal post 150 facing the electrode assembly 120 passes through the end wall 111 and is directly electrically connected to the second electrode tab 125 or indirectly connected via a transfer connection. The structure of the terminal post 150 can be any suitable form that can pass through the end wall 111 and be electrically connected to the second electrode 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 terminal post hole corresponds to the shape of the terminal post 150. In this embodiment, the cross-section of the terminal post 150 is circular.

[0030] Please see Figures 3 to 19The secondary battery 100 also includes a current collector 130, which is disposed on the side of the electrode assembly 120 facing the cover plate 140. The current collector 130 includes a first connecting portion 131 and a second connecting portion 132. The second connecting portion 132 is connected to the first tab 124 of the electrode assembly 120. The welding method can be ultrasonic welding, resistance welding, laser welding, etc., and is not limited thereto. In this embodiment, laser welding is used. The first tab 124 is the negative electrode tab, and copper is the preferred material for the current collector 130. It should be noted that the second connecting portion 132 is the part where the current collector 130 and the first tab 124 are attached. For example, it can be disc-shaped and can be used for welding the current collector 130 and the first tab 124. In order to improve the positioning, processing convenience, interchangeability and uniformity of the current collector 130 during installation, the second connecting portion 132 in this embodiment adopts a circular structure. The first connecting part 131 is arranged around the outer periphery of the second connecting part 132. The first connecting part 131 can be an integral closed ring structure or one or more arc-shaped structures, and there is no limitation thereto.

[0031] Please see Figures 3 to 19 The cover plate 140, the first connecting portion 131, and the side wall 112 are connected by a single weld, requiring only one welding step. This replaces the conventional embodiment where the housing 110 is welded separately to the current collector 130, and the cover plate 140 is welded separately to the housing 110. This reduces the number of welding steps and improves assembly efficiency. Under vibration conditions, the electrode assembly 120 causes axial displacement of the current collector 130 within the secondary battery 100, which can easily lead to pulling on the welded parts of the current collector 130. Please refer to... Figures 3 to 19 In one embodiment of the present invention, the current collecting member 130 further includes a buffer portion 133. On a cross-section passing through the axis of the current collecting member 130 and the first connecting portion 131, the radially inner end of the first connecting portion 131 is defined as the first end 1311, and the radially outer end of the second connecting portion 132 is defined as the second end 1321. The buffer portion 133 connects the first end 1311 and the second end 1321. The length of the buffer portion 133 is L, and the distance from the first end 1311 to the second end 1321 along the axial direction of the housing 110 is W, where L > W > 0. Figure 5 , Figure 12 and Figure 19 As shown. The shape of the buffer section 133 is not limited. The buffer section 133 can be a straight sloping wall, a wavy curved wall, or a combination of various wall shapes, as long as it can form a redundant structure. This setting can achieve the following: under vibration conditions, the electrode assembly 120 drives the current collector 130 to generate axial displacement inside the secondary battery 100. The buffer section 133 can undergo local deformation under tensile force, thereby releasing stress and reducing the tension on the welded joint between the current collector 130 and the housing 110.

[0032] Please see Figures 3 to 19 The combination of the flow collecting component 130, the cover plate 140, and the side wall 112 can take various forms, which can be achieved by designing the structure of the flow collecting component 130, the cover plate 140, and the side wall 112. These will be described in detail below through several embodiments. It should be noted that the form of the first connecting part 131 in the following embodiments is not limited; it can be an integral, closed, surrounding type. For example, the first connecting part 131 can be annular. See [link to relevant documentation] for details. Figure 21 and Figure 22 Alternatively, it can be a type where multiple pins 1314 are spaced around the buffer portion 133 in a circumferential manner, such as... Figure 20 As shown, the two forms of the first connecting part 131 will not be described separately below.

[0033] Please see Figures 3 to 4 In one embodiment of this utility model, the sidewall 112 includes a first stepped portion 114 disposed at one end near the cover plate 140. The first stepped portion 114 includes a first mating surface 1141 facing the cover plate 140, and a first connecting portion 131 is clamped between the cover plate 140 and the first mating surface 1141. The outer peripheral surface of the first connecting portion 131 and the outer peripheral surface of the cover plate 140 are both adapted to the inner surface of the first stepped portion 114. This arrangement facilitates the welding and fixing of the first connecting portion 131, the cover plate 140, and the sidewall 112. The first connecting portion 131, the cover plate 140, and the first stepped portion 114 are connected by a weld stamp. That is, the first connecting portion 131, the cover plate 140, and the first stepped portion 114 are welded and fixed in one laser seam weld. This welding and fixing method simplifies the welding process and improves welding efficiency. In addition, since the laser welding position is located above the cover plate 140 and the seam welding method is used, the first mating surface 1141 is set facing the cover plate 140, which can block the heat from being transferred into the housing 110, thereby reducing the thermal impact of welding heat on the electrode assembly 120.

[0034] Please see Figure 5In one embodiment of this utility model, along the axial direction of the housing 110, the first end 1311 is closer to the cover plate 140 than the second end 1321. The buffer portion 133 includes a first inclined wall 1331, which is disposed between the first end 1311 and the second end 1321. In this embodiment, the first inclined wall 1331 connects the first end 1311 and the second end 1321. The angle between the first inclined wall 1331 and the plane containing the second connecting portion 132 is α, where 90° < α ≤ 135°. The first connecting portion 131 and the second connecting portion 132 have a height difference and are connected by the first inclined wall 1331. Compared to the first connecting portion 131 and the second connecting portion 132 being connected by the shortest path, the first inclined wall 1331 is a redundant structure that can deform under external force. Under vibration conditions, the electrode assembly 120 causes the current collector 130 to undergo axial displacement within the secondary battery 100. The buffer portion 133, subjected to tensile force, can undergo local deformation, thereby releasing stress and reducing the tension on the welded joint between the current collector 130 and the housing 110. The first inclined wall 1331, satisfying 90°<α≤135°, can balance the buffering effect with the structural strength of the current collector 130.

[0035] Please see Figures 3 to 5 In one embodiment of this utility model, a third step portion 141 is provided on the outer periphery of the cover plate 140 facing the electrode assembly 120. The third step portion 141 includes a second inclined wall 1411 and a first annular surface 1412 connected to the radially outer end of the second inclined wall 1411. The first annular surface 1412 faces the first connecting portion 131 and abuts against the first connecting portion 131. This arrangement allows the first connecting portion 131 to be at least partially accommodated in the third step portion 141 along the axial direction of the housing 110. On the other hand, the second inclined wall 1411 can play a role in positioning the current collecting member 130. When the cover plate 140 is pressed down, the second inclined wall 1411 can push the first inclined wall 1331, causing the first connecting portion 131 to move radially outward, so as to facilitate the first connecting portion 131 to reach a preset position. Further, the first annular surface 1412, the first connecting portion 131, and the side wall 112 are connected by solder.

[0036] Please see Figures 6 to 7 In one embodiment of the present invention, with Figures 3 to 5 The difference in the illustrated embodiment is that the buffer portion 133 further includes a first recess 1332 connecting the first inclined wall 1331 and the second end 1321. The side of the first recess 1332 facing the electrode assembly 120 has a protrusion that protrudes from the second connecting portion 132. The provision of the first recess 1332 further increases the redundancy of the buffer portion 133, making the buffer portion 133 have a better buffering effect.

[0037] Please see Figures 8 to 9In one embodiment of the present invention, with Figures 6 to 7 The difference in the illustrated embodiment is that the cover plate 140 includes a second recess 142 recessed towards the flow collecting member 130. A protrusion is formed on the side of the second recess 142 facing the flow collecting member 130. The second recess 142 includes a fifth inclined wall 1421 and a sixth inclined wall 1422 connected at their bottom ends. Along the radial direction of the cover plate 140, the fifth inclined wall 1421 is disposed outside the sixth inclined wall 1422. The fifth inclined wall 1421 and the first inclined wall 1331 of the buffer portion 133 are similar in shape to each other. In this embodiment, as... Figure 9 As shown, the fifth inclined wall 1421 and the first inclined wall 1331 of the buffer portion 133 are similar in shape to each other. This arrangement maximizes the utilization of the receiving space formed by the buffer portion 133 and provides guidance, limiting, and buffering effects during the pressing and assembly process of the cover plate 140. The second recess 142 is formed by stamping, which has the advantages of simpler process and easier forming compared to the process of thinning the edge of the cover plate 140. The second recess 142 helps to enhance the structural strength of the cover plate 140.

[0038] Please see Figures 10 to 12 In one embodiment of the present invention, with Figures 3 to 5 The difference in the illustrated embodiment is that, along the radial direction of the housing 110, the first end 1311 is located inside the second end 1321, and the buffer portion 133 includes a seventh inclined wall 1335, which connects the first end 1311 and the second end 1321. The angle between the plane containing the seventh inclined wall 1335 and the second connecting portion 132 is γ, where 45°≤γ<90°. The seventh inclined wall 1335, satisfying 45°≤γ<90°, allows the cross-sections of the first connecting portion 131, the seventh inclined wall 1335, and the second connecting portion 132 to have a Z-shaped structure. The seventh inclined wall 1335, like a redundant structure capable of deformation in the same position, has a better buffering effect, thereby alleviating the pulling force on the welded joint between the current collecting member 130 and the housing 110.

[0039] Please see Figures 13 to 14In one embodiment of this utility model, the sidewall 112 includes a second stepped portion 115 disposed at one end near the cover plate 140. The second stepped portion 115 includes a second mating surface 1151. The bottom end of the first connecting portion 131 abuts against the second mating surface 1151 and extends in a direction away from the electrode assembly 120. The first connecting portion 131 includes a first end face 1312 connected to the cover plate 140 and a first side face 1313 connected to the inner surface of the second stepped portion 115. The second mating surface 1151 can position the first connecting portion 131 and facilitates the first end face 1312 of the first connecting portion 131 abutting against the cover plate 140, thereby improving the welding quality. The first end face 1312, the first side face 1313, and the outer peripheral surface of the cover plate 140 are connected by a weld stamp. That is, the first end face 1312, the first side face 1313, and the outer peripheral surface of the cover plate 140 are welded and fixed in one laser welding process. This welding and fixing method also simplifies the welding process and improves welding efficiency. At the same time, this arrangement increases the contact area between the first connecting part 131 and the side wall 112, thereby improving the welding reliability of the first connecting part 131 and the side wall 112.

[0040] Please see Figures 13 to 14 Considering that the first connecting portion 131 is vertically arranged in this embodiment, and the first end 1311 of the first connecting portion 131 is located at the bottom end of the first connecting portion 131, the first end 1311 is positioned closer to the electrode assembly 120 than the second end 1321 along the axial direction of the housing 110. The buffer portion 133 connects the first end 1311 and the second end 1321 to form a third inclined wall 1333, replacing the structure in the conventional embodiment where the first end 1311 of the first connecting portion 131 and the second end 1321 of the second connecting portion 132 are at the same height. This arrangement allows the buffer portion 133 between the first connecting portion 131 and the second connecting portion 132 to act as a buffer to resist the pulling of the welded parts on the current collector 130 after the electrode assembly 120 is subjected to external force.

[0041] Please see Figures 15-16 In one embodiment of the present invention, with Figure 13 and Figure 14 The difference between the illustrated embodiments lies in the position and shape of the buffer portion 133, but the similarity is that the cover plate 140 also includes a second recess 142 recessed towards the flow collecting member 130, which maximizes the utilization of the receiving space formed by the buffer portion 133. The second recess 142 is formed by stamping, which has the advantages of simpler and easier forming process compared to the process of thinning the edge of the cover plate 140. The provision of the second recess 142 helps to enhance the structural strength of the cover plate 140 and can also limit the axial movement of the flow collecting member 130.

[0042] Please see Figures 17 to 19In one embodiment of this utility model, the first connecting portion 131 extends in a direction away from the electrode assembly 120. The first connecting portion 131 is sandwiched between the inner wall of the side wall 112 and the outer peripheral surface of the cover plate 140. That is, from the inside to the outside along the radial direction of the housing 110, the components are the cover plate 140, the first connecting portion 131, and the side wall 112. The cover plate 140 has various structures and is not limited thereto. For example, it can be disc-shaped or have an outer periphery with an upward-turned edge. In this embodiment, please refer to... Figure 18 The cover plate 140 has an upwardly folded third connecting portion 1431 on its outer periphery. The outer peripheral surface of the third connecting portion 1431 connects to the first connecting portion 131. This arrangement increases the contact area between the current collecting member 130 and the cover plate 140, which is beneficial for improving welding quality. In addition, the third connecting portion 1431 has a radially outward elastic force, which is beneficial for clamping and fixing the cover plate 140 and the first connecting portion 131, thereby improving welding efficiency and welding quality. The first connecting portion 131, the third connecting portion 1431, and the inner wall of the side wall 112 are connected by a weld stamp. That is, the first connecting portion 131, the third connecting portion 1431, and the side wall 112 are welded and fixed in one laser welding process, which also simplifies the welding process.

[0043] Please see Figure 19 Along the axial direction of the housing 110, the first end 1311 is closer to the electrode assembly 120 than the second end 1321. A buffer portion 133 connects the first end 1311 and the second end 1321, forming a fourth inclined wall 1334. The angle between the fourth inclined wall 1334 and the plane containing the second connecting portion 132 is β, where 15° < β ≤ 45°. The fourth inclined wall 1334 replaces the structure in conventional embodiments where the first end 1311 of the first connecting portion 131 and the second end 1321 of the second connecting portion 132 are at the same height. This arrangement allows the buffer portion 133 between the first connecting portion 131 and the second connecting portion 132 to act as a buffer, resisting the pulling of the welded portion on the current collector 130 after the electrode assembly 120 is subjected to external force.

[0044] Please see Figure 18 In one embodiment of the present invention, the fourth inclined wall 1334 and the first connecting part 131 are connected to form a clearance area 1336 to prevent the third connecting part 1431 from interfering with the current collecting member 130. This arrangement is beneficial to make the end face of the first connecting part 131 away from the electrode assembly 120, the end face of the side wall 112 away from the electrode assembly 120, and the end face of the third connecting part 1431 away from the electrode assembly 120 flush. This arrangement is beneficial to improving the welding quality.

[0045] Please see Figure 18In one embodiment of the present invention, the cover plate 140 includes a third recess 143 recessed toward the flow collecting member 130. In this embodiment, the third recess 143 includes a third connecting portion 1431 located radially outward. The third recess 143 can make maximum use of the receiving space formed by the buffer portion 133. On the other hand, the third connecting portion 1431 is connected to the first connecting portion 131, which increases the contact area between the flow collecting member 130 and the cover plate 140, which is beneficial to improving the welding quality. In addition, the third connecting portion 1431 has a radially outward elastic force, which is beneficial to clamping and fixing the cover plate 140 and the first connecting portion 131, thereby improving welding efficiency and welding quality.

[0046] Please see Figure 20 In one embodiment of this utility model, the first connecting portion 131 includes a plurality of pins 1314 arranged at intervals along the circumference of the buffer portion 133, each pin 1314 being connected to both the cover plate 140 and the inner wall of the side wall 112. The number of pins 1314 is not limited; in this embodiment, there are four pins 1314, which are connected to the outer periphery of the buffer portion 133 and are evenly spaced circumferentially. It should be noted that the first connecting portion 131 in the above embodiments can all be the structural form of this embodiment, and the above embodiments will not be repeated.

[0047] Furthermore, the second connecting portion 132 includes multiple tab connecting portions 1322, which are spaced apart along the circumference of the current collector 130, with the pin 1314 located between two adjacent tab connecting portions 1322. This arrangement allows the welding positions of the pin 1314 and the sidewall 112, as well as the tab connecting portions 1322, to be staggered in the circumference of the current collector 130. This also allows the solder joints between the current collector 130 and the electrode assembly 120, and between the current collector 130 and the housing 110, to be located in different radial directions, achieving stress decoupling and reducing the tensile force at the welding positions of the first connecting portion 131 and the sidewall 112.

[0048] Please see Figures 21 to 23 In one embodiment of the present invention, the current collector 130 further includes at least one thickness reduction portion 134. The thickness reduction portion 134 is disposed on at least one side of the two sides of the second connecting portion 132 along the thickness direction. The thickness reduction portion 134 surrounds the radially outer side of the tab connecting portion 1322. The thickness reduction portion 134 can form a gap on the second connecting portion 132. The gap can cause local deformation of the material when subjected to impact, thereby releasing stress and weakening the stress transmission between the tab connecting portion 1322 and the first connecting portion 131. The thickness reduction portion 134 is a segmented annular or closed annular structure. For example, in one embodiment, such as... Figure 21As shown, along the radial direction of the current collection member 130, a plurality of thickness reduction portions 134 are provided on the side of the second connection portion 132 facing the cover plate 140; the thickness reduction portions 134 are segmented and spaced annular, and are located on the radial outer side of the electrode connection portion 1322. This arrangement can alleviate the stress on the electrode connection portion 1322 to the greatest extent.

[0049] In another embodiment, such as Figure 22 As shown, with Figure 21 The difference lies in the fact that the circumferential length of the thickness-reducing portion 134 is larger, which allows for the release of stress over a greater area. In some other embodiments, such as... Figure 23 As shown, the thickness reduction section 134 is a closed ring. This thickness reduction section 134 is simple to manufacture and can release stress generated at any position in the circumference of the current collector 130. All of the above features can release stress through the thickness reduction section 134 when the battery experiences radial vibration, thereby improving the problem of the current collector moving as a whole in the radial direction and constantly tearing the solder, which leads to welding failure.

[0050] Please see Figure 24 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.

[0051] Please see Figure 25This 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, and space shuttles, 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.

[0052] The beneficial effects of this utility model are as follows: This utility model proposes a secondary battery in which the current collector includes a second connecting portion and a first connecting portion. A buffer portion is provided between the second connecting portion and the first connecting portion. On a cross-section passing through the axis of the current collector and the first connecting portion, the buffer portion connects the first end and the second end. The length of the buffer portion is greater than the distance from the first end to the second end along the axial direction of the casing. This arrangement makes the buffer portion a redundant structure. Under vibration conditions, when the electrode assembly drives the current collector to undergo axial displacement inside the secondary battery, the buffer portion can undergo local deformation under tensile force, thereby releasing stress and reducing the tensile force on the welded joint between the current collector and the casing.

[0053] 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 in that, include: Cover plate; A housing, including sidewalls that form at least one opening circumferentially around the perimeter, and a cover plate that seals at least one of the openings; An electrode assembly is housed within the housing, and the electrode assembly has tabs on the side facing the opening; A current collector is disposed on the side of the electrode assembly facing the cover plate. The current collector includes a first connecting part and a second connecting part. The second connecting part is welded to the electrode tab. The first connecting part is disposed around the outer periphery of the second connecting part. The cover plate, the first connecting part and the side wall are connected by solder. The current collecting component further includes a buffer section. On the cross section passing through the axis of the current collecting component and the first connecting part, the end of the first connecting part located on the radially inner side is the first end, and the end of the second connecting part located on the radially outer side is the second end. The buffer section connects the first end and the second end. The length of the buffer section is L, and the distance from the first end to the second end along the axial direction of the housing is W, where L > W > 0.

2. The secondary battery according to claim 1, characterized in that, The sidewall includes a first stepped portion disposed at one end near the cover plate. The first stepped portion includes a first mating surface facing the cover plate. The first connecting portion is clamped between the cover plate and the first mating surface. The first connecting portion, the cover plate, and the first stepped portion are connected by the solder joint. Along the axial direction of the housing, the first end is closer to the cover plate than the second end. The buffer portion includes a first inclined wall, which is disposed between the first end and the second end. The angle between the first inclined wall and the plane containing the second connecting portion is α, where 90°<α≤135°.

3. The secondary battery according to claim 2, characterized in that, The cover plate has a third step portion on the outer periphery facing the electrode assembly. The third step portion includes a second inclined wall and a first annular surface connected to the radially outer end of the second inclined wall. The second inclined wall faces the first inclined wall and abuts against the first inclined wall. The first annular surface faces the first connecting portion and contacts the first connecting portion. The first annular surface, the first connecting portion and the side wall are connected by the solder mark.

4. The secondary battery according to claim 2, characterized in that, The buffer portion further includes a first recess connecting the first inclined wall and the second end, wherein a protrusion protruding from the second connection portion is formed on the side of the first recess facing the electrode assembly.

5. The secondary battery according to claim 2, characterized in that, Along the radial direction of the housing, inside the first end, the buffer portion includes a seventh inclined wall, which connects the first end and the second end. The angle between the seventh inclined wall and the plane containing the second connecting portion is γ, where 45°≤γ<90°.

6. The secondary battery according to claim 1, characterized in that, The sidewall includes a second stepped portion disposed near one end of the cover plate. The second stepped portion includes a second mating surface. The bottom end of the first connecting portion abuts against the second mating surface and extends in a direction away from the electrode assembly. The first connecting 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, and the outer peripheral surface of the cover plate are connected by solder. Along the axial direction of the housing, the first end is closer to the electrode assembly than the second end, and the buffer portion connects the first end and the second end and forms a third inclined wall.

7. The secondary battery according to claim 1, characterized in that, The first connecting portion extends in a direction away from the electrode assembly, and is sandwiched between the inner wall of the sidewall and the outer peripheral surface of the cover plate. The first connecting portion, the cover plate, and the inner wall of the sidewall are connected by the solder mark. Along the axial direction of the housing, the first end is closer to the electrode assembly than the second end. The buffer portion connects the first end and the second end and forms a fourth inclined wall. The angle between the fourth inclined wall and the plane containing the second connecting portion is β, where 15° < β ≤ 45°.

8. The secondary battery according to any one of claims 2 to 4, characterized in that, The cover plate includes a second recess that is recessed toward the flow collecting member. A protrusion is formed on the side of the second recess facing the flow collecting member. The second recess includes a fifth inclined wall and a sixth inclined wall connected at their bottom ends. Along the radial direction of the cover plate, the fifth inclined wall is disposed outside the sixth inclined wall. The fifth inclined wall and the first inclined wall of the buffer portion are similar in shape to each other.

9. A battery pack, characterized in that, The secondary battery includes any one of claims 1 to 8.

10. An electronic device, characterized in that, Includes the battery pack as described in claim 9.

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