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 shell, electrode assembly and current collecting member. Shell includes rolling groove. At least part of current collecting member is arranged between electrode assembly and rolling groove. Current collecting member includes current collecting body, first connecting part, first bending part, second connecting part and second bending part, and current collecting body is fixedly connected with electrode assembly. First connecting part is connected to the outer edge of current collecting body by first bending part, and is bent to the center of shell. Second connecting part is between first connecting part and rolling groove, and is welded with the surface of rolling groove facing electrode assembly. Wherein, second connecting part is connected to the side of first connecting part close to the center of shell by the second bending part, and forms flip structure with first connecting part. Through the flip structure, stress is released, stress transmission between second connecting part and the weld mark of shell is reduced or even avoided, and the damage to the weld mark between second connecting part and shell is reduced.

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] With the development of lithium battery technology, the energy density of rechargeable batteries is becoming increasingly important. Cylindrical batteries, which can achieve high energy density, have become the mainstream form of rechargeable battery. Existing cylindrical batteries typically have a current collector at one end of the casing. The casing connection of the current collector is welded to the side wall of the casing, and the current collector body is electrically connected to the tabs of the electrode assembly, thus achieving electrical connection between the casing and the electrode assembly. Mechanical sealing is then performed.

[0003] Mechanical sealing involves rolling grooves that are recessed towards the inside of the casing onto the side wall of the casing, placing the cover plate and seals into the grooves, then rolling the casing edge to press it onto the cover plate or seals, and finally pressing the cover plate tightly by a pressing method. However, in existing cylindrical batteries, the weld marks formed after welding the casing connection to the casing are prone to breakage during the mechanical sealing process, especially between the current collector and the casing. Utility Model Content

[0004] This invention provides a secondary battery, a battery pack, and an electronic device to solve the technical problem of reducing solder joint breakage between the casing and the current collector.

[0005] This utility model provides a secondary battery, which includes a housing, an electrode assembly, and a current collector. The housing includes a surrounding sidewall with an opening at one end. The end of the housing near the opening includes a groove recessed into the housing. The electrode assembly is disposed within the housing and located on the side of the groove opposite to the opening. At least a portion of the current collector is disposed between the electrode assembly and the groove. The current collector includes a current collector body and a housing connecting portion, the current collector body being fixedly connected to the electrode assembly. The housing connecting portion includes a first connecting portion, a first bending portion, a second connecting portion, and a second bending portion. The first connecting portion is connected to the outer edge of the current collector body via the first bending portion and bends towards the center of the housing. The second connecting portion is located between the first connecting portion and the groove and is welded to the surface of the groove facing the electrode assembly. The second connecting portion is connected to the side of the first connecting portion near the center of the housing via the second bending portion, forming a folded structure of the housing connecting portion with the first connecting portion.

[0006] In one embodiment of the present invention, the second connecting portion is folded at least once from the side of the first connecting portion near the center of the housing to the side of the first connecting portion away from the current collecting body, so as to form the folding structure.

[0007] In one embodiment of the present invention, the second connecting portion includes a first sub-connecting portion and a welding portion. The first sub-connecting portion is connected to the first connecting portion through the second bending portion. Along the height direction of the secondary battery, the projection of the first sub-connecting portion and the first connecting portion at least partially overlaps. Along the circumferential direction of the secondary battery, the welding portion is integrally connected to the first sub-connecting portion and is located on at least one side of the first connecting portion. The welding portion is welded to the surface of the groove facing the electrode assembly.

[0008] In one embodiment of the present invention, along the circumferential direction of the secondary battery, the length of the welded part is L1 mm, and the length of the first sub-connecting part is L2 mm, wherein 0.25 × L1 ≤ L2 ≤ 4 × L1.

[0009] In one embodiment of the present invention, the length of the welded portion along the circumferential direction of the secondary battery is L1 mm, wherein 2 mm ≤ L1 ≤ 10 mm.

[0010] In one embodiment of this utility model, the second connecting portion includes two welding portions, which are respectively connected to both sides of the first sub-connecting portion along the circumferential direction of the secondary battery. The first sub-connecting portion extends along the circumferential direction of the secondary battery and is connected to the first connecting portion via the second bending portion. Alternatively, the second connecting portion further includes a second sub-connecting portion, in which the first sub-connecting portion extends along the circumferential direction of the secondary battery, a first end of the second sub-connecting portion is connected to the second bending portion, a second end of the second sub-connecting portion is connected to the first sub-connecting portion, and the second sub-connecting portion is folded at least once from the first end toward the side away from the current collector body.

[0011] In one embodiment of the present invention, along the height direction of the secondary battery, the thickness of the second connecting portion is T1 mm, and the thickness of the folding structure is T mm, wherein 0.2 mm ≤ T ≤ 5 × T1.

[0012] In one embodiment of the present invention, along the radial direction of the secondary battery, the width of the first connecting part is H mm, and the width of the second connecting part is H1 mm, wherein 0.1 × H < H1 ≤ 0.9 × H.

[0013] A second aspect of this utility model also provides a battery pack, the battery pack comprising the secondary battery described in any of the preceding claims.

[0014] A third aspect of this invention also provides an electronic device comprising the aforementioned battery pack.

[0015] The beneficial effects of this utility model are as follows: This utility model proposes a secondary battery, a battery pack, and an electronic device. In the structure of this secondary battery, a second connecting part is connected to the second connecting part near the center of the housing via a second bending part, forming a folded structure of the housing connecting part. This strengthens the structural strength of the connection between the housing connecting part and the housing, making it easier for bending to occur between the first connecting part and the current collector body during mechanical sealing. Simultaneously, during mechanical sealing, the folded structure releases stress, reducing or even preventing stress transmission to the weld between the second connecting part and the housing, thus improving the technical problem of weld breakage between the housing and the current collector component. 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:

[0018] Figure 1 This is a schematic diagram of the structure of a secondary battery provided in one embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of an electrode assembly provided in one embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the structure of the flow collection component in the pier sealing state in one embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the structure of the flow collecting component in the ungrooved state in one embodiment of the present invention;

[0022] Figure 5 This is a cross-sectional view of the flow collecting component in the ungrooved state according to one embodiment of the present invention;

[0023] Figure 6 for Figure 5 A magnified structural diagram of region A;

[0024] Figure 7 This is a top view of the flow collection component in the sealed state in one embodiment of the present invention;

[0025] Figure 8 This is a top view of the shell connection portion in a sealed state according to an embodiment of the present invention. Figure 1 ;

[0026] Figure 9This is a top view of the shell connection portion in a sealed state according to an embodiment of the present invention. Figure 2 ;

[0027] Figure 10 This is a top view of the shell connection portion in a sealed state according to an embodiment of the present invention. Figure 3 ;

[0028] Figure 11 This is a schematic diagram of the shell connection portion in a sealed state in one embodiment of the present invention;

[0029] Figure 12 This is a schematic diagram of the structure of an electrode assembly provided in one embodiment of the present invention;

[0030] Figure 13 This is a schematic diagram of the structure of an electronic device provided in one embodiment of the present invention.

[0031] The attached figures are labeled as follows:

[0032] 1. Electronic device; 10. Battery pack; 101. Housing; 102. Cover; 11. Working part; 100. Secondary battery; 110. Housing; 111. End wall; 112. Side wall; 113. Opening; 114. Groove; 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, First electrode tab; 125, Second electrode tab; 130, Cover plate; 140, Current collector component; 141, Current collector body; 142, First connecting part; 143, Second connecting part; 1431, First sub-connecting part; 1432, Welding part; 1433, Second sub-connecting part; 144, Folding structure; 145, First bending part; 146, Second bending part; 150, Electrode post. Detailed Implementation

[0033] 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.

[0034] 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.

[0035] 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.

[0036] Please see Figures 1 to 13 This utility model provides a secondary battery 100, a battery pack 10, and an electronic device 1. A folding structure 144 is formed at the welded joint of the housing 110 through the housing connecting part. During the mechanical sealing process, the stress is released by the folding structure 144, reducing or even avoiding stress transmission to the weld between the second connecting part and the housing. This makes it easier for the bending between the housing connecting part and the current collector 141 to occur, thereby improving the technical problem of weld breakage between the housing 110 and the current collector 140.

[0037] This utility model provides a secondary battery 100, which includes at least a housing 110, an electrode assembly 120, a cover plate 130, and a current collector 140.

[0038] 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.

[0039] Please see Figures 1 to 2Electrode assembly 120 is housed within housing 110 and is a component in the secondary battery 100 where electrochemical reactions occur. Housing 110 may contain one or more electrode assemblies 120. Electrode assembly 120 includes a wound structure formed by stacking and winding a first electrode 121, a second electrode 123, and a separator 122, wherein 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.

[0040] Please see 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 coating area 1212 coated with active material and an empty foil without active material. In order to distinguish it from the empty foil on the second electrode 123, the empty foil is called the first empty foil 1213. The first empty foil 1213 is located at the end of the first electrode 121. The first empty foil 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 it from 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.

[0041] Please see Figure 2 In this embodiment, 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 a second tab 125. The second tab 125 is the corresponding positive tab.

[0042] Please see Figure 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 cylindrical battery 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.

[0043] Further, please refer to Figure 1 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.

[0044] 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 second electrode tab 125 or indirectly connected via a transfer connection. 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 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 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.

[0045] Please see Figure 1 and Figure 3A cover plate 130 is sealed and installed at the opening 113. The outer edge shape of the cover plate 130 corresponds to the shape of the opening 113 and is connected to the side wall 112 to seal the opening 113. In a specific embodiment, the end of the housing 110 near the opening 113 includes a groove 114 recessed into the housing 110. The groove 114 is rolled out from the area near the outer end of the side wall 112 of the housing 110 and recessed into the housing 110. The electrode assembly 120 is disposed inside the housing 110 and is located on the side of the groove 114 opposite to the opening 113. The groove 114 can restrict the movement of the electrode assembly 120 towards the opening 113. An annular step is formed around the housing 110 on the side of the groove 114 opposite to the electrode assembly 120. The cover plate 130 is placed on this step, and a sealing ring is provided between the cover plate 130 and the housing 110. The edge of the opening 113 is sealed by pressing the cover plate 130 against the sealing ring to form a reliable connection.

[0046] Please see Figure 1 The current collector 140 is at least partially disposed between the groove 114 and the electrode assembly 120. The electrode assembly 120 is electrically connected to the housing 110 through the current collector 140. It should be noted that the shape of the current collector 140 can be any rotationally symmetrical shape, such as a circle, square, regular polygon, petal shape, or other shape with a center of symmetry that can coincide with the original shape after rotating around the center of symmetry by a certain angle. There is no limitation on this, as long as a stable and reliable electrical connection can be achieved. The center of the current collector 140 is its own center of symmetry.

[0047] Specifically, please refer to Figure 3 The current collector 140 includes a current collector body 141 and a housing connection portion connected to the outer periphery of the current collector body 141. The current collector body 141 is fixedly electrically connected to the electrode assembly 120, that is, the current collector body 141 is welded to the first electrode tab 124 of the electrode assembly 120. The welding method can be ultrasonic welding, resistance welding, laser welding, etc., and there is no limitation on this method. In this embodiment, laser welding is used. The first electrode tab 124 is the negative electrode tab. Copper is the preferred material for the current collector 140. It should be noted that the current collector body 141 is the part that fits between the current collector 140 and the first electrode tab 124, and can be used for welding the current collector 140 and the first electrode tab 124.

[0048] Please see Figure 3 and Figure 7The housing connection portion can be an integral annular structure or a pin structure arranged in one or more annular patterns, as long as it meets the current conduction requirements and welding strength requirements between the housing connection portion and the housing 110. In this embodiment, the housing connection portion is a pin structure, and multiple housing connection portions are spaced around the outer periphery of the current collector body 141. This can generate a more uniform current conduction effect in the circumferential direction between the current collector 140 and the side wall 112, thereby improving the stability of current conduction between the housing 110 and the electrode assembly 120. The housing connection portion includes a first connection portion 142, a first bend portion 145, a second connection portion 143, and a second bend portion 146. The first connection portion 142 is integrally connected to the outer edge of the current collector body 141 through the first bend portion 145. The integral connection between the first connection portion 142 and the current collector body 141 can be integrally stamped or integrally injection molded. During the secondary battery production process, the casing connecting part is welded to the side wall 112 of the casing 110. The current collector 141 is usually perpendicular to the side wall 112 and welded to the first tab 124 of the electrode assembly. Therefore, the first bending part 145 enables the current collector 141 to be connected to the casing connecting part. The side wall 112 is subjected to processes such as grooving and sealing to seal and fix the cover plate 130 at the opening of the casing 110. During the grooving and sealing process, the current collector 140 inevitably bends, causing the first connecting part 142 to bend towards the center of the casing 110, thereby reducing the bending angle of the first bending part 145.

[0049] The second connecting portion 143 is integrally connected to the first connecting portion 142 near the center of the housing 110 via the second bending portion 146. Along the height direction of the secondary battery, the second connecting portion 143 is located between the first connecting portion 142 and the groove 114, and is welded to the surface of the groove 114 facing the electrode assembly 120. The welding method between the second connecting portion 143 and the surface of the groove 114 facing the electrode assembly 120 is not limited; ultrasonic welding, resistance welding, laser welding, etc., can be used. Along the height direction of the secondary battery, the second connecting portion 143 and the first connecting portion 142 form a folded structure 144 for the housing connection. By adding the folded structure 144 and the second bending portion 146, stress during the mechanical sealing process is released. Simultaneously, during the mechanical sealing process, deformation and bending occur between the first connecting portion 142 and the current collector 141 to release stress, reducing stress transmission to the solder joint and lowering the risk of solder joint breakage at the solder joint. During the sealing process, along the height direction of the secondary battery, the first connecting part 142 is more easily bent from an inclined state to a horizontal state. By adding a folding structure 144 and a second bending part 146, the stress during the mechanical sealing process is released, preventing the first bending part 145 between the first connecting part 142 and the current collector body 141 from inserting into the electrode assembly 120 and thus preventing damage to the electrode assembly 120. At the same time, during the mechanical sealing process, the risk of weld breakage between the second connecting part 143 and the housing 110 is reduced, ensuring the welding connection effect between the housing 110 and the housing connecting part, thereby ensuring the electrical connection stability between the current collector 140 and the housing 110.

[0050] Please see Figure 3 and Figure 5 In one embodiment of the present invention, the second connecting portion 143 is folded at least once from the side of the first connecting portion 142 near the center of the housing 110 to the side of the first connecting portion 142 away from the collector body 141, to form the folded structure 144. During the grooving and sealing process, the folded structure 144 formed by the bending of the first connecting portion 142 and the second connecting portion 143 can better adapt to the deformation of the housing 110 during the grooving and sealing process, and serve as a buffer to prevent the tensile force during the grooving or sealing process from being directly transmitted to the weld between the second connecting portion 143 and the housing 110, thereby reducing the risk of weld breakage between the second connecting portion 143 and the housing 110.

[0051] Please see Figure 7In one embodiment of the present invention, the second connecting portion 143 includes a first sub-connecting portion 1431 and a welding portion 1432. The first sub-connecting portion 1431 is connected to the first connecting portion 142 via a second bending portion 146. Along the height direction of the secondary battery, the projections of the first sub-connecting portion 1431 and the first connecting portion 142 at least partially overlap. Specifically, after the secondary battery is sealed, along the height direction of the secondary battery, the projection of the first sub-connecting portion 1431 on the first connecting portion 142 coincides with the first connecting portion 142. Along the circumferential direction of the secondary battery, the welding portion 1432 is integrally connected to the first sub-connecting portion 1431 and is located on at least one side of the first connecting portion 142. In one embodiment, please refer to... Figure 9 Along the circumferential direction of the secondary battery, the number of welding portions 1432 can be a group, and the welding portions 1432 are integrally connected to one side of the first sub-connecting portion 1431, forming a "7"-shaped structure. In another embodiment, please refer to... Figure 8 The welding portion 1432 can also be in two sets, with the two sets of welding portions 1432 integrally connected to both sides of the first sub-connecting portion 1431 to form a "T"-shaped structure. For other embodiments, please refer to... Figure 10 The housing connection can also be a cross-shaped structure, meaning the bending point of the first connection 142 and the second connection 143 occurs in the main body of the first connection 142. The welding part 1432 is welded to the surface of the electrode assembly 120 facing the groove 114. That is, along the height direction of the secondary battery, the projection of the weld mark formed by the welding part 1432 and the groove 114 on the electrode assembly 120 does not coincide with the projection of the first connection 142 on the electrode assembly 120. The welding part 1432 and the first sub-connection 1431 are misaligned, and there is no direct connection between the first sub-connection 1431 and the housing 110. During the grooving or sealing process, the first sub-connection 1431 can also deform, further preventing the tensile force from being directly transmitted to the connection weld mark between the welding part 1432 and the housing 110, and reducing the risk of weld mark breakage.

[0052] Please see Figure 10 In one embodiment of this utility model, along the circumferential direction of the secondary battery, the length of the welding portion 1432 is L1 mm, and the length of the first sub-connecting portion 1431 is L2 mm, where 0.25 × L1 ≤ L2 ≤ 4 × L1. The length design of the first sub-connecting portion 1431 and the welding portion 1432 ensures that the first sub-connecting portion 1431 can partially or completely cover the stress diffusion area of ​​the welding portion 1432. This allows the deformation of the shell 110 during the forming of the groove 114 to be partially absorbed by the folded structure 144 formed by the first sub-connecting portion 1431 and part of the first connecting portion 142, reducing the risk of weld breakage between the welding portion 1432 and the shell 110, thus meeting the welding and current-carrying requirements between the welding portion 1432 and the shell 110. Specifically, in one embodiment, please refer to... Figure 10When the housing connection is a "T"-shaped or "+"-shaped structure, the welding part 1432 is located on both sides of the first sub-connection part 1431. Along the circumferential direction of the secondary battery, the length of the welding part 1432 ranges from 0.5×L1≤L2≤4×L1. In another embodiment, please refer to... Figure 9 When the shell connection part is a "7" type structure, the length of the welded part 1432 is in the range of 0.25×L1≤L2≤4×L1.

[0053] Please see Figure 10 In one embodiment of this utility model, the length of the welding part 1432 along the circumferential direction of the secondary battery is L1 mm, wherein 2 mm ≤ L1 ≤ 10 mm. The length design of the welding part 1432 ensures that there is sufficient welding contact area between the welding part 1432 and the shell 110, ensuring the length of the weld mark and the welding effect.

[0054] Please see Figure 6 as well as Figure 7 In one embodiment of this utility model, the second connecting portion 143 includes two welding portions 1432, which are respectively connected to both sides of the first sub-connecting portion 1431 along the circumferential direction of the secondary battery. Meanwhile, the first sub-connecting portion 1431 extends along the circumferential direction of the secondary battery and is connected to the first connecting portion 142 via a second bending portion 146. The first connecting portion 142 and the second connecting portion 143 form a "T"-shaped structure.

[0055] In another embodiment, please refer to Figure 10 The second connecting portion 143 further includes a second sub-connecting portion 1433. The first sub-connecting portion 1431 extends along the circumferential direction of the secondary battery. The first end of the second sub-connecting portion 1433 is connected to the second bending portion 146, and the second end of the second sub-connecting portion 1433 is connected to the first sub-connecting portion 1431. The second sub-connecting portion 1433 is folded at least once from the first end toward the side away from the current collecting body 141. That is, the second connecting portion 143 is folded only once relative to the first connecting portion 142, and the main body of the first connecting portion 142 is folded once or more. Multiple stacked second sub-connecting portions 1433 are formed by the folded portions of the first connecting portion 142, thereby forming a folding structure 144 with the first sub-connecting portion 1431.

[0056] Please see Figure 11 In one embodiment of the present invention, along the height direction of the secondary battery, the thickness of the second connecting part 143 is T1 mm, and the thickness of the folding structure 144 is T mm, wherein 0.2 mm ≤ T ≤ 5 × T1, thereby balancing the strength and thickness requirements of the folding structure 144.

[0057] Please see Figure 8In one embodiment of this utility model, along the radial direction of the secondary battery, the width of the first connecting portion 142 is H mm, and the width of the second connecting portion 143 is H1 mm, wherein 0.1 × H < H1 ≤ 0.9 × H. The lower limit design of the width of the second connecting portion 143 ensures the welded connection between the second connecting portion 143 and the housing 110. The width design of the second connecting portion 143 ensures the buffering performance of the folding structure 144 as a buffer zone, avoiding buffer failure.

[0058] Please see Figure 12 The second aspect of 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 a plurality of secondary batteries 100. The plurality of secondary batteries 100 are placed in the housing 101 and are connected in series or in parallel, or a combination of series and parallel connections. The cover 102 seals the housing 101 to protect the plurality of 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.

[0059] Please see Figure 13 This utility model also provides an electronic device, which includes the aforementioned battery pack 10. A working unit 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 unit 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 unit 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.

[0060] This utility model proposes a secondary battery, a battery pack, and an electronic device. In the structure of the secondary battery, the second connecting part is connected to the first connecting part near the center of the shell through the second bending part, forming a folded structure of the shell connecting part. The folded structure releases stress and reduces or even avoids stress transmission to the weld between the second connecting part and the shell, thereby solving the technical problem of how to reduce the weld fracture between the shell and the current collector.

[0061] 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, A housing includes surrounding sidewalls, one end of which is formed with an opening, and the end of the housing near the opening includes a groove recessed into the housing. An electrode assembly is disposed within the housing and located on the side of the groove opposite to the opening; A current collecting component is at least partially disposed between the electrode assembly and the groove; the current collecting component includes a current collecting body and a housing connecting portion, the current collecting body being fixedly connected to the electrode assembly; the housing connecting portion includes a first connecting portion, a first bending portion, a second connecting portion, and a second bending portion, the first connecting portion being connected to the outer edge of the current collecting body through the first bending portion and bending towards the center of the housing; the second connecting portion is located between the first connecting portion and the groove, and is welded to the surface of the groove facing the electrode assembly; The second connecting portion is connected to the side of the first connecting portion near the center of the housing via the second bending portion, and together with the first connecting portion, forms the folded structure of the housing connecting portion.

2. The secondary battery according to claim 1, characterized in that, The second connecting portion is folded at least once from the side of the first connecting portion near the center of the housing towards the side of the first connecting portion away from the current collecting body, to form the folded structure.

3. The secondary battery according to claim 1, characterized in that, The second connecting part includes a first sub-connecting part and a welding part. The first sub-connecting part is connected to the first connecting part through the second bending part. Along the height direction of the secondary battery, the projections of the first sub-connecting part and the first connecting part at least partially overlap. Along the circumferential direction of the secondary battery, the welding part is integrally connected to the first sub-connecting part and is located on at least one side of the first connecting part; the welding part is welded to the surface of the groove facing the electrode assembly.

4. The secondary battery according to claim 3, characterized in that, Along the circumferential direction of the secondary battery, the length of the welded part is L1 mm, and the length of the first sub-connector part is L2 mm; wherein, 0.25×L1≤ L2≤ 4×L1.

5. The secondary battery according to claim 3, characterized in that, Along the circumferential direction of the secondary battery, the length of the welded part is L1 mm, where 2 mm ≤ L1 ≤ 10 mm.

6. The secondary battery according to claim 3, characterized in that, The second connection portion includes two welding portions, which are respectively connected to both sides of the first sub-connection portion along the circumferential direction of the secondary battery; The first sub-connection extends along the circumferential direction of the secondary battery. The first sub-connection is connected to the first connection through the second bending portion. Alternatively, the second connection further includes a second sub-connection. The first sub-connection extends along the circumferential direction of the secondary battery. The first end of the second sub-connection is connected to the second bending portion. The second end of the second sub-connection is connected to the first sub-connection. The second sub-connection is folded at least once from the first end toward the side away from the current collector body.

7. The secondary battery according to claim 6, characterized in that, Along the height direction of the secondary battery, the thickness of the second connecting part is T1 mm, and the thickness of the folding structure is T mm, wherein 0.2 mm ≤ T ≤ 5 × T1.

8. The secondary battery according to claim 1, characterized in that, Along the radial direction of the secondary battery, the width of the first connecting part is H mm, and the width of the second connecting part is H1 mm, wherein 0.1×H < H1 ≤ 0.9×H.

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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