Secondary battery and electronic device

Abstract

The utility model provides a secondary battery and an electronic device. The secondary battery comprises a shell, an electrode assembly, a cover plate and a current collecting component, the shell comprises a surrounding side wall, an opening is formed in one end of the side wall, and the end, close to the opening, of the side wall comprises a rolling groove sunken towards the interior of the shell. The electrode assembly is accommodated in the shell, and the electrode assembly comprises a tab facing the opening; the cover plate is hermetically mounted at the opening; the current collecting component comprises a current collecting body and a shell connecting part arranged on the outer periphery of the current collecting body, the current collecting body is fixedly connected with the tab, and the shell connecting part is bent towards the axis of the shell and welded to the surface, facing the electrode assembly, of the rolling groove; and the current collecting component further comprises a buffer part for connecting the shell connecting part and the current collecting body, and the buffer part is configured to be capable of absorbing bending stress when the shell connecting part is bent, so that the technical problem that the welding of the current collecting component and the tab is easy to fail in the mechanical sealing process of the cylindrical battery can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and particularly relates to a secondary battery and an electronic device. Background Art

[0002] Mechanical sealing is the mainstream packaging method for existing cylindrical batteries. Due to its advantages of mature process and equipment and fast production rhythm, it is widely used. For the existing cylindrical batteries, a current collecting member is usually arranged at a position of the shell close to the opening. One end of the current collecting member is welded to the side wall of the shell, and the other end is electrically connected to the tab of the electrode assembly, so as to realize the electrical connection between the shell and the electrode assembly, and then mechanical sealing is carried out, including rolling a groove recessed towards the inside of the shell on the side wall of the shell, and then pressing the cover plate tightly through a caulking sealing method. In this process, the bending stress generated by the current collecting member will cause the inside of the current collecting member to warp, resulting in the welding joint between the current collecting member and the tab being broken, thus there is a risk of electrical connection failure of the electrode assembly. Summary of the Utility Model

[0003] In view of the above-mentioned disadvantages of the prior art, the utility model provides a secondary battery and an electronic device to improve the technical problem that the welding between the current collecting member and the tab of the cylindrical battery is likely to fail during the mechanical sealing process.

[0004] To achieve the above object and other related objects, the utility model provides a secondary battery, which includes a shell, an electrode assembly, a cover plate and a current collecting member; the shell includes a surrounding side wall, one end of the side wall forms an opening, and one end of the side wall close to the opening includes a groove recessed towards the inside of the shell; the electrode assembly is accommodated in the shell, and the electrode assembly includes a tab facing the opening; the cover plate is hermetically installed at the opening; the current collecting member includes a current collecting body and a shell connection part arranged on the outer periphery of the current collecting body, the current collecting body is fixedly connected to the tab, the shell connection part is bent towards the axis of the shell and is welded to the surface of the groove facing the electrode assembly; wherein, the current collecting member further includes a buffer part connecting the shell connection part and the current collecting body, and the buffer part is configured to absorb the bending stress when the shell connection part is bent.

[0005] In the above technical solution, a buffer part is arranged between the shell connection part and the current collecting body. The buffer part can absorb the bending stress generated when the shell connection part is bent, weaken the transmission of the bending stress of the shell connection part to the fixed connection between the current collecting body and the tab, and improve the problem of welding failure between the current collecting member and the tab caused by the bending stress.

[0006] In an example of the secondary battery of the utility model, the buffer part includes an arched protrusion protruding from the current collecting body and extending along the circumferential direction of the outer periphery of the current collecting body, and the buffer part forms a depression on the opposite side of the arched protrusion.

[0007] In the above technical solution, for the buffer portion protruding from the current collector body, when the bending stress generated during the bending of the housing connection portion is transmitted to the current collector body, under the action of the bending stress, a straightening deformation occurs, which can absorb a part of the bending stress, weaken the transmission of the bending stress of the housing connection portion to the connection between the current collector body and the tab, and improve the problem of welding failure between the current collector component and the tab caused by the bending stress.

[0008] In an example of the secondary battery of the present utility model, the thickness of the current collector body is a, and the height of the buffer portion protruding from the current collector body is b, where 0.5a ≤ b ≤ 3a.

[0009] In the above technical solution, the height of the buffer portion protruding from the current collector body is set to be greater than or equal to 0.5a to enable the buffer portion to have a deformation space, and set to be less than or equal to 3a, which can avoid the buffer portion interfering with the bending of the housing connection portion due to excessive height and is also conducive to material saving.

[0010] In an example of the secondary battery of the present utility model, along the radial direction of the current collector component, the distance from the inner side of the arched protrusion to the outer peripheral edge of the current collector component is c, where b ≤ c ≤ 4 mm.

[0011] In the above technical solution, setting b to be less than or equal to c can ensure that there is enough space between the housing connection portion and the current collector body to accommodate the buffer portion. Setting the distance c from the inner side of the arched protrusion to the outer peripheral edge of the current collector component to be less than or equal to 4 mm can make the buffer portion have a relatively close distance to the housing connection portion, which is more conducive to absorbing the bending stress and weakening the transmission of the bending stress of the housing connection portion to the connection between the current collector body and the tab.

[0012] In an example of the secondary battery of the present utility model, a first weak portion extending along the circumferential direction of the current collector component is provided on the buffer portion, and the first weak portion is configured to weaken the strength of the buffer portion.

[0013] In the above technical solution, the setting of the first weak portion is conducive to weakening the strength of the relief portion and is more conducive to the deformation of the relief portion to weaken the transmission of the bending stress of the housing connection portion to the connection between the current collector body and the tab.

[0014] In an example of the secondary battery of the present utility model, the current collector component includes a plurality of housing connection portions and a plurality of buffer portions respectively connected to each housing connection portion. The plurality of buffer portions are circumferentially connected around the outer peripheral edge of the current collector body. The housing connection portion includes a bending portion connected to the buffer portion, and notches are respectively provided on both sides of the bending portion and / or the buffer portion along the circumferential direction of the housing.

[0015] In the above technical solution, multiple housing connection parts are separated and surround the outer peripheral edge of the current collector body. On the one hand, it has high structural strength and a large contact area, which can improve the heat dissipation performance and reduce the resistance. At the same time, it also has the effects of reducing material use and stress concentration. Each housing connection part is correspondingly connected with a buffer part, and each buffer part can absorb the bending stress for the corresponding housing connection part, improving the uniformity and balance of the force on the current collector component, and further improving the current guiding stability of the current collector component. The setting of the notch can reduce the width of the bending part and / or the buffer part, thereby reducing the strength of the bending part and / or the buffer part, making it easy to deform and facilitating the absorption of bending stress. In addition, the notch in the bending part can reduce the bending stress generated when the housing connection part is bent. The combination of the above effects can weaken the transmission of the bending stress to the welding connection part between the current collector component and the tab, thereby improving the problem of welding failure between the current collector component and the tab caused by the bending stress.

[0016] In an example of the secondary battery of the present utility model, the sum of the minimum current-carrying areas of all the bending parts is s1, the sum of the minimum current-carrying areas of all the buffer parts is s2, and the total area of the welding lines formed by welding the current collector body and the tabs is s. Among them, s1 > s and s2 > s.

[0017] In the above technical solution, the minimum current-carrying area of the bending part is the minimum value of the cross-sectional area of each bending part along the circumferential direction of the current collector component, the minimum current-carrying area of the buffer part is the minimum value of the cross-sectional area of each buffer part along the circumferential direction of the current collector component, and the total area of the welding lines refers to the area of the projection of all the welding lines formed by connecting the tab connection part and the tabs along the axial direction of the electrode assembly. The setting that the sum s1 of the minimum current-carrying areas of all the bending parts and the sum s2 of the minimum current-carrying areas of all the buffer parts are both greater than the total area s of the welding lines can weaken the transmission of the bending stress without affecting the current-carrying effect of the bending part and the buffer part.

[0018] In an example of the secondary battery of the present utility model, the housing connection part includes a bending part connected to the buffer part, and a second weak part extending along the circumferential direction of the current collector component is provided on the bending part, and the second weak part is configured to weaken the strength of the bending part.

[0019] In the above technical solution, a second weak part is provided on the bent part, which can weaken the stress generated when the housing connecting part is bent. At the same time, due to the relatively low strength of the second weak part, under the action of stress, the second weak part of the bent part deforms first to reduce the transmission of stress towards the current collector member and the welding connection part of the tab, thereby improving the problem of welding failure between the current collector member and the tab caused by bending stress. At the same time, the second weak part can also play a role in guiding and positioning the bending of the bent part, improving the accuracy of the bending position of the bent part, and being beneficial to improving the consistency of the assembly quality of the secondary battery. In addition, when welding the housing connecting part and the housing before grooving, the second weak part can also be used as a reference line for the welding position to facilitate the positioning of the welding head during welding.

[0020] In an example of the secondary battery of the present utility model, the sum of the minimum current-carrying areas of all the second weak parts is s3, and the total area of the welding line formed by welding the current collector body and the tab is s, where s3 > s.

[0021] In the above technical solution, the minimum current-carrying area of the second weak part is the minimum at the cross-sectional area of each second weak part along the circumferential direction of the current collector member. The setting that the sum s3 of the minimum current-carrying areas of all the second weak parts is greater than the total area s of the welding line can weaken the transmission of bending stress without affecting the current-carrying effect of the second weak part.

[0022] The present utility model also provides an electronic device, which includes a battery pack, and the battery pack includes the secondary battery according to any one of the above.

[0023] In the secondary battery of the present utility model, a buffer part is provided between the housing connecting part and the current collector body. The buffer part can absorb the bending stress generated when the housing connecting part is bent, weaken the transmission of the bending stress of the housing connecting part to the fixed connection part of the current collector body and the tab, and improve the problem of welding failure between the current collector member and the tab caused by bending stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for description in the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other embodiments can be obtained based on these drawings.

[0025] Figure 1 It is a schematic diagram of the overall structure of an example of the secondary battery of the present utility model;

[0026] Figure 2 It is a schematic diagram of the electrode assembly structure of an example of the secondary battery of the present utility model;

[0027] Figure 3 Structural schematic diagram of the current collector member before bending in an embodiment of the secondary battery of the present utility model;

[0028] Figure 4 is Figure 3 Partial enlarged view of location A in

[0029] Figure 5 is Figure 3 Front view of the current collector member in

[0030] Figure 6 is Figure 5 Partial enlarged view of location B in

[0031] Figure 7 Structural schematic diagram of the current collector member before bending in a second embodiment of the secondary battery of the present utility model;

[0032] Figure 8 is Figure 7 Partial enlarged view of location C in

[0033] Figure 9 Structural schematic diagram of the current collector member before bending in a third embodiment of the secondary battery of the present utility model;

[0034] Figure 10 is Figure 9 Partial enlarged view of location D in

[0035] Figure 11 Structural schematic diagram of the current collector member before bending in a fourth embodiment of the secondary battery of the present utility model;

[0036] Figure 12 is Figure 11 Partial enlarged view of location E in

[0037] Figure 13 is Figure 11 Front view of the current collector member in

[0038] Figure 14 is Figure 13 Partial enlarged view of location F in

[0039] Figure 15 Structural schematic diagram of the current collector member before bending in a fifth embodiment of the secondary battery of the present utility model;

[0040] Figure 16 is Figure 15 Partial enlarged view of location G in

[0041] Figure 17 Structural schematic diagram of the current collector member before bending in a sixth embodiment of the secondary battery of the present utility model;

[0042] Figure 18 isFigure 17 Partial enlarged view at H in the middle

[0043] Figure 19 Schematic diagram of an example of a battery pack in the electronic device of the present utility model

[0044] Figure 20 Schematic diagram of an example of the electronic device of the present utility model

[0045] Description of component numbers

[0046] 1. Electronic device; 10. Battery pack; 11. Working part; 101. Box body; 102. Box cover; 100. Secondary battery; 110. Shell; 111. End wall; 112. Side wall; 113. Opening; 114. Rolling groove; 1141. First side wall; 1142. Second side wall; 120. Electrode assembly; 121. Positive electrode tab; 1211. Positive current collector; 1212. First coating area; 1213. First uncoated area; 122. Separator; 123. Negative electrode tab; 1231. Negative current collector; 1232. Second coating area; 1233. Second uncoated area; 124. Negative electrode ear; 125. Positive electrode ear; 130. Cover plate; 140. Terminal; 150. Current collecting member; 151. Current collecting body; 152. Shell connecting part; 1521. Bending part; 1522. Notch; 1523. Second weak part; 153. Buffer part; 1531. First weak part; 154. Ear connecting part Specific embodiments

[0047] The following specific examples illustrate the embodiments of the present utility model. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. The present 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 the present utility model. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. It should also be understood that the terms used in the embodiments of the present utility model are for the purpose of describing specific implementation schemes, rather than limiting the protection scope of the present utility model. The test methods without specific conditions noted in the following embodiments are usually carried out under conventional conditions or according to the conditions recommended by each manufacturer

[0048] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present utility model, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present utility model, based on the understanding of those skilled in the art of the present technology field of the prior art and the description of the present utility model, any methods, devices, and materials similar or equivalent to the prior art in the methods, devices, and materials in the embodiments of the present utility model can also be used to implement the present utility model.

[0049] It should be noted that the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of clear narration, rather than to limit the scope of implementation of the present utility model. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope of implementation of the present utility model.

[0050] The secondary battery includes an electrode assembly, which is a component in the secondary battery where an electrochemical reaction occurs and can include one or more electrode assemblies.

[0051] The secondary battery further includes a housing, a cover plate, and a terminal post. The housing includes an end wall and a side wall surrounding the end wall. One end of the side wall has an opening, and the electrode assembly can be assembled into the housing through the opening of the housing. The cover plate is used to cover the opening of the housing to achieve sealing, and the terminal post passes through the end wall and is electrically connected to the electrode assembly to conduct the electrical energy generated by the electrode assembly.

[0052] The mainstream packaging method of existing secondary batteries is mechanical sealing. Mechanical sealing has the advantages of mature processes and equipment and fast production beats, and is widely used. The current collector member is electrically connected to both the electrode assembly and the housing simultaneously to achieve the electrical connection between the electrode assembly and the housing. Specifically, first, a rolling groove that is recessed towards the inside of the housing is rolled on the side wall of the housing. The edge of the current collector member is pressed tightly on the side close to the electrode assembly. This rolling groove can limit the axial displacement of the electrode assembly. The cover plate is installed on the step formed on the side of the rolling groove away from the electrode assembly. A sealing member is provided between the cover plate and the housing. Then, the cover plate is pressed tightly against the sealing member by means of pier sealing at the edge of the opening to form a reliable connection and achieve the sealing of the housing.

[0053] There are various connection methods between the current collector member and the housing. A common one is: a housing connection portion is provided at the edge of the current collector member. First, the housing connection portion is welded and fixed to the side wall of the housing, and then the rolling groove is rolled on the side wall to make the housing connection portion continue to bend towards the axis of the housing. However, the inventor found that when the housing connection portion bends towards the axis of the housing, bending stress will be generated, and the bending stress will further be transmitted into the current collector member, resulting in the warping inside the current collector member, causing the welding joint between the current collector member and the tab to be broken, thus posing a risk of electrical connection failure of the electrode assembly.

[0054] In view of this, the present utility model provides a technical solution, in which a buffer portion is provided between the housing connection portion and the current collector body. This buffer portion can absorb the bending stress generated when the housing connection portion is bent, weaken the transmission of the bending stress of the housing connection portion to the connection between the current collector body and the tab fixing portion, and improve the problem of welding failure between the current collector member and the tab caused by the bending stress.

[0055] Please refer to Figures 1 to 20 , the present utility model provides a secondary battery 100, which includes: a housing 110, an electrode assembly 120, a terminal 140, a cover plate 130, and a current collector member 150.

[0056] Please refer to 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 relationship 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 split welding. The surrounding of the side wall 112 is not limited, and it can be surrounded in a cylindrical or prismatic shape, or can be surrounded 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, the side wall 112 is surrounded in a cylindrical shape around the outer edge of the end wall 111, and a circular opening 113 is formed at one end of the side wall 112 facing away from the end wall 111. An accommodation cavity is formed inside the housing 110 surrounded by the end wall 111 and the side wall 112 for accommodating the electrode assembly 120, the electrolyte, and other necessary battery components. Specifically, the diameter size of the housing 110 can be determined according to the specific size of the electrode assembly 120, such as 18 mm, 21 mm, 46 mm, etc. The material of the housing 110 can be various, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the housing 110 from rusting during long-term use, a layer of rust-proof material such as metal nickel can also be plated on the surface of the housing 110.

[0057] Please refer to Figures 1 to 2 , the electrode assembly 120 is disposed inside the housing 110, and the electrode assembly 120 is a component that undergoes an electrochemical reaction in the secondary battery 100. One or more electrode assemblies 120 can be included inside the housing 110. The electrode assembly 120 includes electrode plates and a separator 122, and the electrode plates and the separator 122 are wound to form a wound structure. Specifically, in this embodiment, the electrode assembly 120 includes a positive electrode plate 121, a separator 122, and a negative electrode plate 123 wound around the axis of the housing 110.

[0058] Please refer to Figures 1 to 2, the positive electrode tab 121 includes a positive current collector 1211 and a positive active material layer coated on the positive current collector 1211. A first coated area 1212 coated with the positive active material layer and a first uncoated area 1213 not coated with the positive active material layer are formed on the positive current collector 1211. The first coated area 1212 and the first uncoated area 1213 are arranged along the axial direction of the housing 110. The first uncoated area 1213 extends to the outside of the separator 122 at one end in the height direction of the secondary battery 100 and bends towards the axis of the housing 110 to form a stacked positive electrode tab 125.

[0059] Please refer to Figures 1 to 2 , the negative electrode tab 123 includes a negative current collector 1231 and a negative active material layer coated on the negative current collector 1231. A second coated area 1232 coated with the negative active material layer and a second uncoated area 1233 not coated with the negative active material layer are formed on the negative current collector 1231. The second coated area 1232 and the second uncoated area 1233 are arranged along the axial direction of the housing 110. The second uncoated area 1233 extends to the outside of the separator 122 at the other end in the height direction of the secondary battery 100 and bends towards the axis of the housing 110 to form a stacked negative electrode tab 124.

[0060] Please refer to Figures 1 to 2 , the separator 122 is disposed between the positive electrode tab 121 and the negative electrode tab 123 to isolate the positive active material layer and the negative active material layer. Taking the lithium-ion secondary battery 100 as an example, the material of the positive current collector 1211 can be aluminum, and the positive active material layer includes a positive active material, which can be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, etc. The material of the negative current collector 1231 can be copper, and the negative active material layer includes a negative active material, which can be carbon or silicon, etc. The base material of the separator 122 can be polypropylene (PP for short) or polyethylene (PE for short), etc. To protect and insulate the battery cell, an insulating film can also be coated on the outside of the battery cell, and the insulating film can be synthesized from PP, PE, polyethylene terephthalate (PET for short), polyvinyl chloride (PVC for short) or other polymer materials.

[0061] Please refer to Figure 1 and Figure 2Further, the positive electrode tab 125 in the present invention faces the end wall 111 or the opening 113, and the negative electrode tab 124 faces the other end of the housing 110. In this embodiment, the positive electrode tab 125 faces the end wall 111 and is electrically connected to the pole 140 so that the pole 140 is positively charged, and the negative electrode tab 124 faces the opening 113, and the housing 110 is electrically connected to the negative electrode tab 124, so that it is negatively charged. However, in other embodiments, the negative electrode tab 124 can be connected to the pole 140, and the positive electrode tab 125 can be connected to the housing 110.

[0062] See also Figure 1 , the cover plate 130 is sealed and installed on 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, a circle of rolling grooves 114 recessed toward the inside of the shell 110 is rolled out in the area near the outer end of the side wall 112 of the shell 110, and the rolling grooves 114 include a first side wall 1141 and a second side wall 1142. The first side wall 1141 is close to the electrode assembly 120 and can limit the axial displacement of the electrode assembly 120. The side of the second side wall 1142 away from the rolling groove 114 forms an annular step around the shell 110, and the cover plate 130 is placed on the step. A sealing ring is arranged between the cover plate 130 and the annular groove 1121. The edge of the opening 113 is sealed in a manner so that the cover plate 130 presses the sealing ring to form a reliable connection.

[0063] See also Figures 1 to 2 , the pole 140 is fixed to the end wall 111 and electrically connected to the electrode assembly 120. Specifically, the end wall 111 is provided with a pole hole, and the pole 140 is installed through the pole hole and insulated from the end wall 111. The end of the pole 140 facing the electrode assembly 120 passes through the end wall 111 to be directly electrically connected to the positive pole ear 125 or is electrically connected through an indirect transfer. The structure of the pole 140 can be any suitable form that can pass through the end wall 111 and be electrically connected to the positive pole ear 125 of the electrode assembly 120. For example, the cross-section can be circular, square, prismatic, or a special-shaped profile that can achieve stable conductivity. The pole hole corresponds to the shape of the pole 140. In this embodiment, the cross-section of the pole 140 is circular.

[0064] See also Figure 1, a current collecting member 150 is disposed between the electrode assembly 120 and the cover plate 130, and the housing 110 and the electrode assembly 120 are electrically connected through the current collecting member 150. Specifically, the current collecting member 150 includes a current collecting body 151 and a housing connection portion 152 connected to the outer peripheral edge of the current collecting body 151. The housing connection portion 152 may be an integral annular structure or one or more sector-annular structures, as long as the current guiding requirements and welding strength requirements between the current collecting member 150 and the housing 110 are satisfied. Before the housing 110 is roll-formed with the rolling groove 114, the housing connection portion 152 is first welded to the side wall 112 of the housing 110. While the rolling groove 114 is being formed, the housing connection portion 152 welded to the housing 110 continues to bend towards the axis of the housing 110, and finally forms a structure that bends towards the axis of the housing 110 and is welded to the surface of the rolling groove 114 facing the electrode assembly 120.

[0065] Please refer to Figure 3 , Figure 7 , Figure 9 , Figure 11 , Figure 15 and Figure 17 , the current collecting body 151 is fixedly connected to the tab. There are various ways to connect the current collecting body 151 and the tab. For example, it can be a welding connection or a conductive adhesive bonding connection, etc. As long as the electrical connection between the current collecting member 150 and the tab can be achieved and the current guiding requirements are satisfied. In this embodiment, a welding connection method is adopted. Further, the part of the current collecting body 151 welded to the tab is the tab connection portion 154. The shape and position of the tab connection portion 154 are not limited. Preferably, in this embodiment, four tab connection portions 154 for welding to the tab are formed on the current collecting body 151, and the four tab connection portions 154 are evenly arranged in an array along the circumferential direction of the current collecting body 151. This setting can make the welding balance stability between the current collecting member 150 and the tab better, and has a more uniform current guiding effect, thereby improving the stability of current guiding between the housing 110 and the electrode assembly 120.

[0066] Considering that when the housing connection portion 152 bends towards the axis of the housing 110, bending stress will be generated, and the bending stress will further be transmitted into the current collecting member 150, which will cause the problem of the interior of the current collecting member 150 warping. Please refer to Figures 3 to 18 , the current collecting member 150 further includes a buffer portion 153 connecting the housing connection portion 152 and the current collecting body 151. The form of the buffer portion 153 can be various. For example, it can be an elastic structure, an elastic material, etc. that can easily deform to absorb the bending stress when the housing connection portion 152 is bent. There is no limitation in this regard. The buffer portion 153 can weaken the transmission of the bending stress of the housing connection portion 152 to the fixed connection between the current collecting body 151 and the tab, and improves the problem of welding failure between the current collecting member 150 and the tab caused by the bending stress.

[0067] Please refer to Figures 3 to 18 In an example of the secondary battery 100 of the present utility model, the buffer portion 153 includes an arched protrusion that protrudes from the current collector body 151 and extends circumferentially along the outer peripheral edge of the current collector body 151. The buffer portion 153 is formed with a depression on the side opposite to the arched protrusion. When the bending stress generated when the housing connection portion 152 is bent is transmitted to the current collector body 151, the buffer portion 153 generates a stretching deformation under the action of the bending stress, which can absorb part of the bending stress and weaken the transmission of the bending stress of the housing connection portion 152 to the current collector body 151 and the fixed connection portion of the ear. This improves the problem of welding failure between the current collector member 150 and the ear caused by the bending stress. The direction of the arched protrusion is not limited and can protrude towards the cover plate 130 or towards the electrode assembly 120. Preferably, the arched protrusion in this embodiment protrudes towards the cover plate 130. This setting does not occupy the axial space of the housing 110, and the larger accommodation space of the housing 110 is conducive to increasing the energy density.

[0068] Please refer to Figures 3 to 6 In an example of the secondary battery 100 of the present utility model, the thickness of the current collector body 151 is a, and the height of the buffer portion 153 protruding from the current collector body 151 is b, where 0.5a ≤ b ≤ 3a. For example, b can be 0.5a, 0.75a, a, 1.25a, 1.5a, 1.75a, 2a, 2.5a, or 3a, etc. The height of the buffer portion 153 protruding from the current collector body 151 is set to be greater than or equal to 0.5a to enable the buffer portion 153 to have a deformation space. It is set to be less than or equal to 3a to avoid the buffer portion 153 interfering with the bending of the housing connection portion 152 due to being too high, and it is also conducive to material saving.

[0069] Please refer to Figures 3 to 6 In an example of the secondary battery 100 of the present utility model, along the radial direction of the current collector member 150, the distance from the inner side of the arched protrusion to the outer peripheral edge of the current collector member 150 is c, where b ≤ c ≤ 4 mm. Setting b to be less than or equal to c can achieve that there is enough space between the housing connection portion 152 and the current collector body 151 to accommodate the buffer portion 153. The distance c from the inner side of the arched protrusion to the outer peripheral edge of the current collector member 150 is set to be less than or equal to 4 mm. For example, it can be 4 mm, 3.5 mm, 3 mm, 2.5 mm, 2 mm, 1.5 mm, or 1 mm, etc., as long as it is less than b. The value of b can be adaptively adjusted according to the actual situation. This setting can make the buffer portion 153 have a relatively close distance to the housing connection portion 152, which is more conducive to absorbing the bending stress and weakening the transmission of the bending stress of the housing connection portion 152 to the current collector body 151 and the fixed connection portion of the ear.

[0070] Please refer toFigures 11 to 18 , in an example of the secondary battery 100 of the present utility model, a first weak portion 1531 extending along the circumferential direction of the current collector member 150 is provided on the buffer portion 153. The form of the first weak portion 1531 can be various. For example, it can be one or a combination of thinning, scoring, or hollowing, as long as it can weaken the strength of the buffer portion 153 and facilitate the deformation of the buffer portion 153, thereby weakening the transmission of the bending stress of the housing connection portion 152 to the current collector body 151 and the connection portion of the ear.

[0071] Please refer to Figures 3 to 18 , in an example of the secondary battery 100 of the present utility model, the current collector member 150 includes a plurality of housing connection portions 152 and a plurality of buffer portions 153 respectively connected to each housing connection portion 152. The plurality of buffer portions 153 are connected around the outer peripheral edge of the current collector body 151. This setting has, on the one hand, a relatively high structural strength and a relatively large contact area, so as to improve the heat dissipation performance and reduce the resistance effect. At the same time, it also has the effects of reducing material use and reducing stress concentration. Further, in order to facilitate the positioning connection between the housing connection portion 152 and the current collector member 150, in this embodiment, the plurality of housing connection portions 152 have the same shape, and the plurality of housing connection portions 152 are arranged in an array along the circumferential direction of the current collector body 151. Such a setting can generate a more uniform current guiding effect in the circumferential direction between the current collector member 150 and the side wall 112, thereby improving the stability of current guiding between the housing 110 and the electrode assembly 120. Further, each housing connection portion 152 is respectively connected to a buffer portion 153, and each buffer portion 153 can absorb the bending stress for the corresponding housing connection portion 152, improving the uniformity and balance of the force on the current collector member 150, and further improving the current guiding stability of the current collector member 150.

[0072] Please refer to Figures 7 to 18 , in an example of the secondary battery 100 of the present utility model, the housing connection portion 152 includes a bending portion 1521 connected to the buffer portion 153. Notches 1522 are respectively provided on both sides of the bending portion 1521 and / or the buffer portion 153 along the circumferential direction of the housing 110. It includes only openings 113 provided on both sides of the bending portion 1521, or only notches 1522 provided at both ends of the buffer portion 153, and notches 1522 can also be provided at both ends of the bending portion 1521 and the buffer portion 153; the setting of the notches 1522 can reduce the width of the bending portion 1521 and / or the buffer portion 153, thereby reducing the strength of the bending portion 1521 and / or the buffer portion 153, making it easy to deform and facilitating the absorption of bending stress. In addition, the notch 1522 of the bending portion 1521 can reduce the bending stress generated when the housing connection portion 152 is bent. The combination of the above effects can weaken the transmission of the bending stress towards the welding connection portion of the current collector member 150 and the ear, thereby improving the problem of welding failure between the current collector member 150 and the ear caused by the bending stress.

[0073] Please refer to Figures 3 to 18 , in an example of the secondary battery 100 of the present utility model, the sum of the minimum current-carrying areas of all the bending portions 1521 is s1, the sum of the minimum current-carrying areas of all the buffer portions 153 is s2, and the total area of the welding lines formed by welding the current collector body 151 and the tab is s. Among them, s1>s and s2>s. It should be noted that the minimum current-carrying area of the bending portion 1521 is the minimum at the cross-sectional area of each bending portion 1521 along the circumferential direction of the current collector member 150, the minimum current-carrying area of the buffer portion 153 is the minimum at the cross-sectional area of each buffer portion 153 along the circumferential direction of the current collector member 150, and the total area of the welding lines refers to the area of the projection of all the weld imprints formed by welding the current collector body 151 and the tab along the axial direction of the electrode assembly 120. The setting that the sum s1 of the minimum current-carrying areas of all the bending portions 1521 and the sum s2 of the minimum current-carrying areas of all the buffer portions 153 are both greater than the total area s of the welding lines can weaken the transmission of the bending stress while not affecting the current-carrying effect of the bending portion 1521 and the buffer portion 153.

[0074] Please refer to Figures 3 to 18 , in an example of the secondary battery 100 of the present utility model, the housing connection portion 152 includes a bending portion 1521 connected to the buffer portion 153. A second weak portion 1523 extending along the circumferential direction of the current collector member 150 is provided on the bending portion 1521. The form of the second weak portion 1523 can be various. For example, it can be one or a combination of thinning, scoring, or hollowing, as long as it can weaken the strength of the bending portion 1521 and facilitate the deformation of the bending portion 1521. By providing the second weak portion 1523 on the bending portion 1521, the stress generated when the housing connection portion 152 is bent can be weakened. At the same time, due to the low strength of the second weak portion 1523, under the action of the stress, the second weak portion 1523 of the bending portion 1521 is deformed first, so as to reduce the transmission of the stress to the welding connection part between the current collector member 150 and the tab, thereby improving the problem of welding failure between the current collector member 150 and the tab caused by the bending stress. At the same time, the second weak portion 1523 can also play a role in guiding and positioning the bending of the bending portion 1521, improving the accuracy of the bending position of the bending portion 1521, and being beneficial to improving the consistency of the assembly quality of the secondary battery 100. In addition, when welding the housing connection portion 152 and the housing 110 in front of the rolling groove 114, the second weak portion 1523 can also be used as a reference line for the welding position, facilitating the positioning of the welding head during welding.

[0075] Please refer to Figures 3 to 18, in an example of the secondary battery 100 of the present utility model, the minimum current-carrying area of the second weak part 1523 is s3, and the total area of the welding lines formed by welding the current collector body 151 and the tab is s. Here, s3 > s. It should be noted that the minimum current-carrying area of the second weak part 1523 is the minimum of the cross-sectional areas of each second weak part 1523 along the circumferential direction of the current collector member 150. The setting that the sum s3 of the minimum current-carrying areas of all the second weak parts 1523 is greater than the total area s of the welding lines can weaken the transmission of bending stress while not affecting the current-carrying effect of the second weak part 1523.

[0076] In an embodiment of the secondary battery 100 of the present utility model, please refer to Figures 3 to 6 , four housing connection parts 152 are arranged around the outer peripheral edge of the current collector body 151. A buffer part 153 is arranged between each housing connection part 152 and the current collector body 151. The buffer part 153 is an arched protrusion protruding towards the cover plate 130. The dimension of the thickness a of the current collector body 151 is 0.2 mm, the dimension of the height b by which the buffer part 153 protrudes from the current collector body 151 is 0.4 mm, and the dimension of the distance c from the inner side of the arched protrusion to the outer peripheral edge of the current collector member 150 is 3.5 mm. A second weak part 1523 for reducing the strength of the bending part 1521 is arranged on the bending part 1521, and the second weak part 1523 adopts a thinning structure. The setting of this thinning structure weakens the stress generated when the housing connection part 152 is bent, and at the same time weakens the strength of the bending part 1521. Under the action of the stress, the second weak part 1523 of the bending part 1521 deforms first, so as to reduce the transmission of stress towards the welded connection part between the current collector member 150 and the tab, and further improve the problem of welding failure between the current collector member 150 and the tab caused by bending stress.

[0077] In a second embodiment of the secondary battery 100 of the present utility model, please refer to Figures 7 to 8 , which is different from the first embodiment in that: notches 1522 for reducing the strength of the bending part 1521 are arranged at both ends of the bending part 1521. The setting of the notches 1522 can reduce the width of the bending part 1521, further reduce the strength of the bending part 1521, make it easy to deform, and is beneficial to absorbing bending stress. In addition, the notches 1522 of the bending part 1521 can reduce the bending stress generated when the housing connection part 152 is bent. The combination of the above effects can weaken the transmission of bending stress towards the welded connection part between the current collector member 150 and the tab, and further improve the problem of welding failure between the current collector member 150 and the tab caused by bending stress.

[0078] In a third embodiment of the secondary battery 100 of the present utility model, please refer to Figures 9 to 10, which is different from an embodiment in that: notches 1522 for reducing the strength of the buffer portion 153 are provided at both ends of the buffer portion 153. The provision of the notches 1522 can reduce the width of the buffer portion 153, thereby reducing the strength of the buffer portion 153, making it easy to deform and facilitating the absorption of bending stress, so as to weaken the transmission of the bending stress towards the welded connection part of the current collector member 150 and the tab, and further improving the problem of welding failure between the current collector member 150 and the tab caused by the bending stress.

[0079] In the fourth embodiment of the secondary battery 100 of the present utility model, please refer to Figures 11 to 14 , which is different from the second embodiment in that: a first weak portion 1531 is provided on the buffer portion 153. The form of the first weak portion 1531 is a thinned structure, and this thinned structure can weaken the strength of the buffer portion 153, facilitating the deformation of the buffer portion 153, and further weakening the transmission of the bending stress of the housing connection portion 152 to the fixed connection part of the current collector body 151 and the tab.

[0080] In the fifth embodiment of the secondary battery 100 of the present utility model, please refer to Figures 15 to 16 , four housing connection portions 152 are provided around the outer periphery of the current collector body 151. A buffer portion 153 is provided between each housing connection portion 152 and the current collector body 151. The buffer portion 153 is an arched protrusion protruding towards the cover plate 130. The dimension of the thickness a of the current collector body 151 is 0.2 mm, the dimension of the height b by which the buffer portion 153 protrudes from the current collector body 151 is 0.4 mm, and the dimension of the distance c from the inner side of the arched protrusion to the outer periphery of the current collector member 150 is 3.5 mm. A first weak portion 1531 is provided on the buffer portion 153. The form of the first weak portion 1531 is a hollow structure, that is, a plurality of through holes are provided along the circumferential direction of the buffer portion 153. The shape of the through holes can be a round hole, an oblong hole or a kidney-shaped hole, etc., and no limitation is made thereto. In this embodiment, it is a round hole. Further, notches 1522 for reducing the strength of the bending portion 1521 are provided at both ends of the bending portion 1521, and a second weak portion 1523 capable of further reducing the strength of the bending portion 1521 is also provided. The second weak portion 1523 adopts a thinned structure. The combined action of the first weak portion 1531, the second weak portion 1523 and the notch 1522 can better weaken the transmission of the bending stress towards the welded connection part of the current collector member 150 and the tab, and further improve the problem of welding failure between the current collector member 150 and the tab caused by the bending stress.

[0081] In the sixth embodiment of the secondary battery 100 of the present utility model, please refer to Figures 17 to 18 , the shape of the through hole is a kidney-shaped hole, and the hollowed-out area formed by the kidney-shaped hole in the buffer portion 153 is larger, having a better effect of weakening the strength of the buffer portion 153.

[0082] Please refer to Figure 20, the present utility model also provides an electronic device 1, and the electronic device 1 includes a battery pack 10. The battery pack 10 includes the secondary battery 100 of any one of the above. In an embodiment of the battery pack 10 of the present utility model, please refer to Figure 19 , the battery pack 10 includes a box body 101, a box cover 102 and a plurality of secondary batteries 100. The plurality of secondary batteries 100 are placed in the box body 101 and are connected in series or in parallel with each other, or a mixture of series and parallel connections. The box cover 102 covers the box body 101 to protect the plurality of secondary batteries 100. It should be noted that in addition to the secondary battery 100 of the present utility model, the battery pack 10 may also include parts such as a battery pack thermal management system and a circuit board. The battery pack 10 may be a battery module or a battery pack, an energy storage electric cabinet, etc.; details will not be elaborated here one by one.

[0083] The electronic device 1 further includes a working part 11, and the working part 11 is electrically connected to the battery pack 10 to obtain power support. As an example, the electronic device 1 is a vehicle, and the vehicle may be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc., but is not limited thereto. The working part 11 is the vehicle body, and the battery pack 10 is arranged at the bottom of the vehicle body and provides power support for the running of the vehicle or the operation of the electrical components in the vehicle. However, in some other embodiments, the electronic device 1 may also be a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy and an electric tool, etc. The spacecraft includes an airplane, a rocket, a space shuttle and a spaceship, etc.; the working part 11 may be a unit component that can obtain the electric energy of the battery pack 10 and perform corresponding work, such as the fan blade rotation unit of a fan, the dust suction working unit of a vacuum cleaner, etc. The electric toy includes a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy and an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and a railway electric tool, for example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator and a planer, etc. The embodiments of the present application do not impose special restrictions on the above-mentioned electronic device 1.

[0084] For the secondary battery of the present utility model, a buffer portion is provided between the housing connection portion and the current collector body. This buffer portion can absorb the bending stress generated when the housing connection portion is bent, weakening the transmission of the bending stress of the housing connection portion to the connection between the current collector body and the ear fixing point, and improving the problem of welding failure between the current collector component and the ear caused by the bending stress. Therefore, the present utility model effectively overcomes some practical problems in the prior art and thus has high utilization value and practical significance. The above embodiments are only illustrative of the principles and effects of the present utility model and are not intended to limit the present utility model. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present utility model. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present utility model should still be covered by the claims of the present utility model.

Claims

1. A secondary battery, characterized in that: include: The shell comprises a surrounding side wall, one end of the side wall is formed with an opening, and one end of the side wall close to the opening comprises a rolling groove recessed toward the inside of the shell; an electrode assembly, contained in the housing, the electrode assembly comprising a tab facing the opening; A cover plate, sealingly mounted on the opening; A current collecting component, comprising a current collecting body and a shell connecting portion arranged at the outer periphery of the current collecting body, wherein the current collecting body is fixedly connected to the electrode tab, and the shell connecting portion is bent toward the axis of the shell and welded to the surface of the rolling groove facing the electrode assembly; Wherein, the current collecting component further includes a buffer portion connecting the shell connecting portion and the current collecting body, and the buffer portion is configured to absorb bending stress when the shell connecting portion is bent.

2. The secondary battery according to claim 1, characterized in that: The buffer portion includes an arched protrusion protruding from the current collecting body and extending along the circumferential direction of the outer peripheral edge of the current collecting body. The buffer portion is formed as a recess on a side opposite to the arched protrusion.

3. The secondary battery according to claim 2, characterized in that: The thickness of the current collecting body is a, and the height of the buffer portion protruding from the current collecting body is b, wherein 0.5a≤b≤3a.

4. The secondary battery according to claim 3, characterized in that: Along the radial direction of the current collecting member, the distance from the inner side of the arched protrusion to the outer peripheral edge of the current collecting member is c, wherein b≤c≤4 mm.

5. The secondary battery according to claim 2, characterized in that: The buffer portion is provided with a first weak portion extending along the circumferential direction of the current collecting member, and the first weak portion is configured to weaken the strength of the buffer portion.

6. The secondary battery according to claim 1, characterized in that: The current collecting component includes a plurality of shell connecting parts and a plurality of buffer parts connected to each of the shell connecting parts in a one-to-one correspondence, the plurality of buffer parts are connected to the outer periphery of the current collecting body in a surrounding manner, the shell connecting part includes a bending part connected to the buffer part, and the bending part and / or the buffer part are respectively provided with notches on both sides along the circumference of the shell.

7. The secondary battery according to claim 6, characterized in that: The sum of the minimum flow areas of all the bending portions is s1, the sum of the minimum flow areas of all the buffer portions is s2, and the total area of ​​the welding line formed by welding the current collecting body and the tab is s, wherein s1>s, s2>s.

8. The secondary battery according to claim 6, characterized in that: The housing connection portion includes a bending portion connected to the buffer portion, and a second weak portion extending along the circumferential direction of the current collecting member is disposed on the bending portion, and the second weak portion is configured to weaken the strength of the bending portion.

9. The secondary battery according to claim 8, characterized in that: The sum of the minimum flow areas of all the second weak parts is s3, and the total area of ​​the welding line formed by welding the current collecting body and the tab is s, wherein s3>s.

10. An electronic device, characterized in that: A battery pack is provided, wherein the battery pack includes the secondary battery according to any one of claims 1 to 9.

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