Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a secondary battery, a battery pack and an electronic device. The secondary battery comprises a shell, an electrode assembly 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 shell 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 current collecting component comprises a current collecting body and a shell connecting part connected to 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; n first notches are formed in the outer periphery, facing the axis of the shell, of the shell connecting part, n is larger than or equal to 1, and the technical problem that welding failure of a current collecting component and a tab is prone to occurring in the mechanical sealing process of the cylindrical battery can be solved.

Description

Technical Field

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

[0002] Mechanical sealing is the mainstream packaging method for existing cylindrical batteries. It is widely used because of its advantages of mature technology and equipment and fast production cycle. In the prior art cylindrical batteries, a current collecting component is usually set near the opening of the shell, so that one end of the current collecting component is welded to the side wall of the shell, and the other end is electrically connected to the pole ear of the electrode assembly, thereby realizing the electrical connection between the shell and the electrode assembly, and then mechanical sealing is performed, including rolling a groove on the side wall of the shell that is concave toward the inside of the shell, and then the cover plate is pressed by a sealing method. In this process, the bending stress generated by the current collecting component will cause the internal part of the current collecting component to warp, resulting in the welding point between the current collecting component and the pole ear being pulled off, thereby causing the risk of failure of the electrical connection of the electrode assembly. Utility Model Content

[0003] In view of the above shortcomings of the prior art, the utility model provides a secondary battery, a battery pack and an electronic device to improve the technical problem that the current collecting components and the tab welding failures are prone to occur in the mechanical sealing process of cylindrical batteries.

[0004] To achieve the above-mentioned purpose and other related purposes, the utility model provides a secondary battery, which comprises: a shell, an electrode assembly and a current collecting component; the shell comprises a surrounding side wall, one end of the side wall is formed with an opening, and the end of the shell close to the opening comprises a rolling groove recessed into the shell; the electrode assembly is accommodated in the shell, and the electrode assembly comprises a pole ear facing the opening; the current collecting component comprises a current collecting body and a shell connecting part connected to the outer periphery of the current collecting body, the current collecting body is fixedly connected to the pole ear, the shell connecting part is bent toward the axis of the shell, and is welded to the surface of the rolling groove facing the electrode assembly; the outer periphery of the shell connecting part facing the axis of the shell is provided with n first notches, n≥1.

[0005] In the above technical scheme, a first notch is set at the outer periphery of the shell connecting part. When the shell connecting part is bent toward the axis of the shell, the outer periphery of the shell connecting part needs to be bent to a position with a smaller diameter. The setting of the first notch, on the one hand, reduces the area at the outer periphery of the shell connecting part and reduces the generation of excess extruded material. On the other hand, the first notch can also accommodate excess extruded material, thereby improving the technical problems in the prior art that the outer periphery of the shell connecting part cannot be bent flat and there is a large stress transfer, thereby achieving the flatness of the bending of the shell connecting part and improving the reliability of the connection between the shell connecting part and the shell. At the same time, it also weakens the bending stress of the shell connecting part and improves the problem of welding failure between the current collecting component and the pole ear caused by bending stress.

[0006] In an example of the secondary battery of the present utility model, the width of the root of the first notch is b, and the width of the top of the first notch is a, where 0.1 mm ≤ b ≤ a ≤ 2 mm.

[0007] In the above technical solution, the width of the top of the first notch is greater than or equal to the width of the root of the first notch. Since the diameter of the housing connection part is larger closer to the top, more redundant extruded material is generated during bending. This setting can better accommodate the redundant extruded material generated during the bending of the housing connection part. The maximum value of the width of the first notch is limited within 2 mm, so as to reduce the bending stress of the housing connection part while taking into account the strength of the housing connection part and the reliability of connection with the housing.

[0008] In an example of the secondary battery of the present utility model, before the housing connection part is bent, the distance from the outer peripheral edge of the housing connection part to the side of the current collector body facing away from the electrode assembly is d, and the depth of the first notch is c, where 0.5d ≤ c < d.

[0009] In the above technical solution, the housing connection part forms an approximately 90° angle with the current collector body before bending. The depth of the first notch is set to c < d, that is, the root of the first notch is higher than the side of the current collector body facing away from the electrode assembly, which can make the housing connection part have higher strength and roundness when designing the first notch, facilitating the reliability of welding with the housing. It is limited that c ≥ 0.5d, that is, the depth of the first notch is greater than or equal to half of the height of the housing connection part, so as to ensure that the first notch has sufficient space to accommodate the extruded material.

[0010] In an example of the secondary battery of the present utility model, the current collector member includes a plurality of housing connection parts, and the plurality of housing connection parts are arranged around the outer peripheral edge of the current collector body.

[0011] In the above technical solution, the plurality of housing connection parts are separated and arranged around the outer peripheral edge of the current collector body. On the one hand, it has high structural strength and a 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.

[0012] In an example of the secondary battery of the present utility model, along the circumferential direction of the housing, the housing connection part is divided into n + 1 connecting segments by the first notch. The surface of the housing connection part and the rolling groove facing the electrode assembly is welded to form at least n + 1 first weld marks, and there is at least one first weld mark on each connecting segment.

[0013] In the above technical solution, each connecting section on each shell connecting part is welded to the shell to form at least one first weld mark, that is, each connecting section is welded to the shell respectively, and no welding is done at the first notch. This arrangement can realize stable welding of the shell connecting part and the shell without affecting the independent bending between each connecting section. The strength of each connecting section is relatively small and easy to deform, which is conducive to absorbing the bending stress generated when the shell connecting part is bent, thereby improving the problem of welding failure between the current collecting component and the pole ear caused by bending stress.

[0014] In an example of the secondary battery of the present invention, the width of any one of the first notches is less than or equal to 0.2 mm, and the shell connection portion and the surface of the rolling groove facing the electrode assembly are welded to form at least one second weld mark, and each second weld mark is continuous and spans all the first notches.

[0015] In the above technical solution, multiple connecting sections on the shell connecting part are welded to the shell to form a continuous second weld mark. The continuous second weld mark is conducive to improving the welding efficiency. The width of any one of the first notches is limited to less than or equal to 0.2 mm, so that the first notch is formed into a narrow gap. Even if the second weld mark is welded across the first notch, the first notch within this size range is conducive to being filled with molten material formed during welding, so as to reduce the situation where the shell is welded through at the first notch.

[0016] In an example of the secondary battery of the present utility model, the penetration depth of the second weld mark at the first notch position is less than 0.7 of the shell thickness.

[0017] In the above technical solution, the penetration depth of the second weld mark in the first notch is set to be less than 0.7 of the shell thickness, which can reduce the risk of welding through the shell.

[0018] In an example of the secondary battery of the present utility model, the shell connecting portion includes a bent portion connected to the current collecting body, and the bent portion is provided with second notches on both sides along the circumference of the shell.

[0019] In the above technical solution, the setting of the second notch can reduce the width of the bending portion, thereby reducing the bending stress generated when the shell connection portion is bent. At the same time, the strength of the bending portion is reduced and it is easy to deform, which is beneficial to absorb the bending stress and weaken the transmission of the bending stress to the welding connection part of the current collecting component and the pole ear, thereby improving the problem of welding failure between the current collecting component and the pole ear caused by bending stress.

[0020] In an example of the secondary battery of the present invention, the shell connecting portion includes a bent portion connected to the current collecting body, and a weak portion extending along the circumferential direction of the shell is provided on the bent portion.

[0021] In the above technical solution, a weak portion is provided on the bending portion, which can weaken the stress generated by the shell connection portion when being bent. At the same time, due to the low strength of the weak portion, the weak portion of the bending portion is deformed first under the action of stress to reduce the transmission of stress to the welding connection portion of the current collecting component and the pole lug, thereby improving the problem of welding failure between the current collecting component and the pole lug caused by bending stress. At the same time, the weak portion can also guide and position the bending of the bending portion, improve the accuracy of the bending position of the bending portion, and help improve the consistency of the secondary battery assembly quality. In addition, when the shell connection portion and the shell are welded before the groove is rolled, the weak portion can also be used as a reference line for the welding position, which is convenient for positioning the welding head during welding.

[0022] In an example of the secondary battery of the present invention, the sum of the minimum flow areas of all weak parts is e, and the total area of ​​the welding line formed by welding the current collecting body and the tab is s, where e>s.

[0023] In the above technical solution, the minimum flow area of ​​the weak part is the minimum cross-sectional area of ​​each weak part along the circumferential direction of the current collecting component. The total area of ​​the welding wire formed by welding the current collecting body and the electrode ear refers to the projection area of ​​the welding wire itself along the axial direction of the electrode assembly. The minimum flow area of ​​all weak parts, this sum e, is greater than the total area s of the welding wire. This can weaken the transmission of bending stress without affecting the flow effect of the weak part.

[0024] The utility model also provides a battery pack, which comprises any one of the above-mentioned secondary batteries.

[0025] The utility model also provides an electronic device, which comprises the battery pack mentioned above.

[0026] The utility model secondary battery has a first notch on the outer periphery of the shell connecting part. When the shell connecting part is bent toward the shell axis, the outer periphery of the shell connecting part needs to be bent to a position with a smaller diameter. The provision of the first notch, on the one hand, reduces the area at the outer periphery of the shell connecting part, reduces the generation of excess extruded material, and on the other hand, the first notch can also accommodate excess extruded material, thereby improving the technical problems in the prior art that the outer periphery of the shell connecting part cannot be bent flat and there is a large stress transmission, thereby achieving the flatness of the bending of the shell connecting part, improving the reliability of the connection between the shell connecting part and the shell, and at the same time weakening the bending stress of the shell connecting part, thereby improving the problem of welding failure between the current collecting component and the pole ear caused by the bending stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0028] Figure 1 This is a schematic diagram of the overall structure of an example of a secondary battery of the utility model;

[0029] Figure 2 This is a schematic diagram of the structure of an electrode assembly of an example of a secondary battery of the utility model;

[0030] Figure 3 This is a schematic structural diagram of a current collecting component of an example of a secondary battery of the utility model before being bent;

[0031] Figure 4 for Figure 3 The front view of the middle current collecting component;

[0032] Figure 5 for Figure 3 Schematic diagram of the structure of the middle current collecting component after bending;

[0033] Figure 6 This is a schematic structural diagram of a current collecting component of an example of a secondary battery of the utility model before being bent;

[0034] Figure 7 for Figure 6 The front view of the middle current collecting component;

[0035] Figure 8 for Figure 6 Schematic diagram of the structure of the middle current collecting component after bending;

[0036] Fig. 9 This is a schematic structural diagram of a current collecting component of an example of a secondary battery of the utility model before being bent;

[0037] Fig.10 for Fig. 9 The front view of the middle current collecting component;

[0038] Fig.11 for Fig. 9 Schematic diagram of the structure of the middle current collecting component after bending;

[0039] Fig.12 This is a schematic structural diagram of a current collecting component of an example of a secondary battery of the utility model before being bent;

[0040] Fig.13 for Fig.12 The front view of the middle current collecting component;

[0041] Fig.14 A schematic diagram of an example of a battery pack of the utility model;

[0042] Fig.15 It is a schematic diagram of an example of the electronic device of the present invention.

[0043] Component number description

[0044] 1. electronic device; 10. battery pack; 11. working part; 101. box; 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 sheet; 1211. positive electrode current collector; 1212. first coating area; 1213. first uncoated area; 122. diaphragm; 123. negative electrode Pole piece; 1231, negative electrode current collector; 1232, second coating area; 1233, second uncoated area; 124, negative electrode tab; 125, positive electrode tab; 130, cover plate; 140, pole column; 150, current collecting component; 151, current collecting body; 152, shell connecting part; 1521, first notch; 1522, first weld mark; 1523, second weld mark; 1524, bending part; 1525, second notch; 1526, weak part; 153, tab connecting part. DETAILED DESCRIPTION

[0045] The following describes the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and the features in the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific implementation schemes, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0046] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present invention, 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 invention are in accordance with the prior art mastery of those skilled in the art and the description of the present invention, and any method, device and material of the prior art similar or equivalent to the method, device and material in the embodiments of the present invention can also be used to implement the present invention.

[0047] 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 description and are not used to limit the scope of implementation of the present utility model. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present utility model without substantially changing the technical content.

[0048] The secondary battery includes an electrode assembly, which is a component in the secondary battery where electrochemical reactions occur, and may include one or more electrode assemblies.

[0049] The secondary battery also includes a shell, a cover plate and a pole. The shell includes an end wall and a side wall surrounding the end wall. One end of the side wall has an opening. The electrode assembly can be assembled into the shell through the opening of the shell. The cover plate is used to cover the opening of the shell to achieve sealing. The pole passes through the end wall and is electrically connected to the electrode assembly to conduct the electrical energy generated by the electrode assembly.

[0050] The mainstream packaging method of existing secondary batteries is mechanical sealing. Mechanical sealing has the advantages of mature technology and equipment and fast production cycle, and is widely used. The current collecting component is electrically connected to the electrode assembly and the shell at the same time to achieve electrical connection between the electrode assembly and the shell. Specifically, a rolling groove that is concave toward the inside of the shell is first rolled on the side wall of the shell. The side of the rolling groove close to the electrode assembly presses the edge of the current collecting component. The 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 seal is provided between the cover plate and the shell, and then the edge of the opening is sealed to make the cover plate press the seal to form a reliable connection and achieve the sealing of the shell.

[0051] There are many ways to connect the current collecting component and the shell. One commonly used method is: a shell connecting part is provided on the edge of the current collecting component, the shell connecting part is first welded and fixed to the side wall of the shell, and then a groove is rolled on the side wall to allow the shell connecting part to continue to bend toward the axis of the shell. However, the inventors found that when the shell connecting part is bent toward the axis of the shell, the outer periphery of the shell connecting part has to be bent to a position with a smaller diameter, and the outer periphery of the shell connecting part will produce excess extruded material that cannot be accommodated, thereby generating a large stress transfer, causing the internal part of the current collecting component to warp, resulting in the welding point between the current collecting component and the pole ear being pulled apart, thereby causing the risk of electrical connection failure of the electrode assembly.

[0052] In view of this, the utility model provides a technical solution, in which a first notch is arranged at the outer periphery of the shell connection part. On the one hand, the area at the outer periphery of the shell connection part is reduced, reducing the generation of excess extruded material. On the other hand, the first notch can also accommodate excess extruded material, thereby improving the technical problem in the prior art that the outer periphery of the shell connection part cannot be bent flat, weakening the bending stress of the shell connection part, and improving the problem of welding failure between the current collecting component and the pole ear caused by bending stress.

[0053] See also Figures 1 to 15 The utility model provides a secondary battery 100 , which includes: a shell 110 , an electrode assembly 120 , a pole 140 and a current collecting component 150 .

[0054] See also Figure 1 The shell 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 a variety of ways, such as integral stamping, integral casting or split welding. The surrounding of the side wall 112 is not limited, and can be cylindrical or prismatic, 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, and the side wall 112 is cylindrical and surrounds the outer edge of the end wall 111, and a circular opening 113 is formed at one end of the side wall 112 away from the end wall 111. A housing cavity is formed in the shell 110 surrounded by the end wall 111 and the side wall 112, which is used to accommodate the electrode assembly 120, the electrolyte and other necessary battery components. Specifically, the diameter of the shell 110 can be determined according to the specific size of the electrode assembly 120, such as 18mm, 21mm, 46mm, etc. The shell 110 may be made of a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the shell 110 from rusting during long-term use, a layer of rust-proof material such as metal nickel may be plated on the surface of the shell 110.

[0055] See also Figure 1 to Figure 2 The electrode assembly 120 is disposed inside the housing 110. The electrode assembly 120 is a component where an electrochemical reaction occurs in the secondary battery 100. The housing 110 may contain one or more electrode assemblies 120. The electrode assembly 120 includes a pole piece and a separator 122, which are wound to form a winding structure. Specifically, in this embodiment, the electrode assembly 120 includes a positive pole piece 121, a separator 122, and a negative pole piece 123 axially wound around the housing 110.

[0056] See also Figure 1 to Figure 2The positive electrode sheet 121 includes a positive electrode collector 1211 and a positive electrode active material layer coated on the positive electrode collector 1211. A first coated area 1212 coated with the positive electrode active material layer and a first uncoated area 1213 not coated with the positive electrode active material layer are formed on the positive electrode collector 1211. The first coated area 1212 and the first uncoated area 1213 are arranged axially along the shell 110. The first uncoated area 1213 extends to the outside of the diaphragm 122 at one end in the height direction of the secondary battery 100, and is bent toward the axis of the shell 110 to form a stacked positive electrode ear 125.

[0057] See also Figure 1 to Figure 2 The negative electrode sheet 123 includes a negative electrode current collector 1231 and a negative electrode active material layer coated on the negative electrode current collector 1231, and a second coating area 1232 coated with the negative electrode active material layer and a second uncoated area 1233 not coated with the negative electrode active material layer are formed on the negative electrode current collector 1231. The second coating area 1232 and the second uncoated area 1233 are arranged axially along the shell 110, and the second uncoated area 1233 extends to the outside of the diaphragm 122 toward the other end in the height direction of the secondary battery 100, and is bent toward the axis of the shell 110 to form a stacked negative electrode tab 124.

[0058] See also Figure 1 to Figure 2 , the diaphragm 122 is arranged between the positive electrode plate 121 and the negative electrode plate 123 to isolate the positive electrode active material layer and the negative electrode active material layer. Taking the lithium-ion secondary battery 100 as an example, the material of the positive electrode current collector 1211 can be aluminum, the positive electrode active material layer includes the positive electrode active material, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganate, etc. The material of the negative electrode current collector 1231 can be copper, the negative electrode active material layer includes the negative electrode active material, and the negative electrode active material can be carbon or silicon, etc. The base material of the diaphragm 122 can be polypropylene (PP for short) or polyethylene (PE for short), etc. In order 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 by PP, PE, polyethylene terephthalate (PET for short), polyvinyl chloride (PVC for short) or other high molecular polymer materials.

[0059] See also 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.

[0060] 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.

[0061] See also Figure 1 to Figure 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.

[0062] See also Figure 1The current collecting component 150 is disposed between the electrode assembly 120 and the cover plate 130. The shell 110 and the electrode assembly 120 are electrically connected via the current collecting component 150. Specifically, the current collecting component 150 includes a current collecting body 151 and a shell connecting portion 152 connected to the outer periphery of the current collecting body 151. The shell connecting portion 152 may be an integral annular structure or one or more fan-shaped annular structures, as long as the flow conduction requirements and welding strength requirements between the current collecting component 150 and the shell 110 are met. Before the shell 110 is rolled with the groove 114, the shell connecting portion 152 is first welded to the side wall 112 of the shell 110. While the groove 114 is rolled, the shell connecting portion 152 welded to the shell 110 continues to bend toward the axis of the shell 110, and finally forms a structure that is bent toward the axis of the shell 110 and is welded to the surface of the groove 114 facing the electrode assembly 120. Please refer to Figure 1 , Figure 5 , Figure 8 and Fig.11 .

[0063] See also Figure 3 , Figure 5 , Figure 6 , Figure 8 , Fig. 9 , Fig.11 and Fig.12 The current collecting body 151 is fixedly connected to the pole tab. There are many ways to connect the current collecting body 151 and the pole tab, such as welding connection or conductive adhesive connection, as long as the electrical connection between the current collecting component 150 and the pole tab can be achieved and the current conduction requirements can be met. In this embodiment, the welding connection method is adopted. Furthermore, the part where the current collecting body 151 is welded to the pole tab is the pole tab connection part 153, and the shape and position of the pole tab connection part 153 are not limited. Preferably, in this embodiment, four pole tab connection parts 153 welded to the pole tab are formed on the current collecting body 151, and the four pole tab connection parts 153 are arranged in a uniform array along the circumference of the current collecting body 151. This arrangement can make the welding balance stability between the current collecting component 150 and the pole tab better, and have a more uniform current conduction effect, thereby improving the stability of current conduction between the shell 110 and the electrode assembly 120.

[0064] See also Figures 3 to 13Considering that when the shell connecting part 152 is bent toward the axis of the shell 110, the outer periphery of the shell connecting part 152 has to be bent to a position with a smaller diameter, the outer periphery of the shell connecting part 152 will produce excess extruded material that cannot be accommodated, thereby generating a larger stress transfer. Furthermore, n first notches 1521 are provided on the outer periphery of the shell connecting part 152 facing the axis of the shell 110, where n≥1, and n can be set to any number according to the size and shape of the shell connecting part 152, for example, it can be 1, 2, 3, 4, 5, 6 or more, and there is no limitation on this. The provision of the first notch 1521, on the one hand, reduces the area at the outer periphery of the shell connection part 152 and reduces the generation of excess extruded material, and on the other hand, the first notch 1521 can also accommodate excess extruded material, thereby improving the technical problem in the prior art that the outer periphery of the shell connection part 152 cannot be bent flat and there is a large stress transfer, thereby achieving the flatness of the bending of the shell connection part 152 and improving the reliability of the connection between the shell connection part 152 and the shell 110, while also weakening the bending stress of the shell connection part 152 and improving the problem of welding failure between the current collecting component 150 and the pole ear caused by bending stress.

[0065] Since the diameter of the shell connecting portion 152 closer to the top is larger, more excess extrusion is generated when bending. In order to better accommodate the excess extrusion generated when the shell connecting portion 152 is bent, please refer to Figures 3 to 13 In an example of the secondary battery 100 of the utility model, the width of the root of the first notch 1521 is b, and the width of the top of the first notch 1521 is a. Preferably, 0.1mm≤b≤a≤2mm, the sizes of a and b can be the same, or a>b, for example, the values ​​of a and b can be: 0.1mm, 0.2mm, 0.3mm, 0.5mm, 0.7mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.5mm, 1.7mm, 1.8mm, 1.9mm or 2mm, etc. The maximum value of the width of the first notch 1521 is limited to within 2mm, so that while reducing the bending stress of the shell connecting part 152, the strength of the shell connecting part 152 and the reliability of the connection with the shell 110 can be taken into account.

[0066] In order to further reduce the bending stress of the shell connecting portion 152, please refer to Figures 3 to 13, in an example of the secondary battery 100 of the present utility model, before the housing connection part 152 is bent, the distance from the outer peripheral edge of the housing connection part 152 to the side of the current collector body 151 facing away from the electrode assembly 120 is d, and the depth of the first notch 1521 is c. Preferably, 0.5d ≤ c < d. For example, the value of c can be 0.5d, 0.6d, 0.7d, 0.8d, 0.9d, etc. It should be noted that before the housing connection part 152 is bent, it forms an approximately 90° angle with the current collector body 151. The depth of the first notch 1521 is set to c < d, that is, the depth of the first notch 1521 is higher than the side of the current collector body 151 facing away from the electrode assembly 120, which can make the housing connection part 152 have higher strength and roundness when designing the first notch 1521, facilitating the reliability of welding with the housing 110. Defining c ≥ 0.5d, that is, the depth of the first notch 1521 is greater than or equal to half of the height of the housing connection part 152, so as to ensure that the first notch 1521 has sufficient space to accommodate the extruded material.

[0067] In order to reduce the bending stress of the housing connection part 152, in an example of the secondary battery 100 of the present utility model, please refer to Figures 3 to 13 , the current collector member 150 includes a plurality of housing connection parts 152, and the plurality of housing connection parts 152 are arranged around the outer peripheral edge of the current collector body 151. This setting has, on the one hand, higher structural strength and a larger 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 part 152 and the current collector member 150, in this embodiment, the plurality of housing connection parts 152 have the same shape, and the plurality of housing connection parts 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.

[0068] Please refer to Figures 3 to 13In an example of the secondary battery 100 of the utility model, along the circumference of the shell 110, the shell connection part 152 is divided into n+1 connection sections by n first notches 1521, and the shell connection part 152 and the surface of the rolling groove 114 facing the electrode assembly 120 are welded to form n+1 or more first weld marks 1522, and n can be set to any number according to the size and shape of the shell connection part 152, for example, it can be 1, 2, 3, 4, 5, 6 or more. There is no limitation on this, and there is at least one first weld mark 1522 on each connection section. That is, each connection section is welded to the shell 110 respectively, and no welding is done at the first notch 1521. This setting can realize the stable welding of the shell connection part 152 and the shell 110, and does not affect the independent bending between each connection section. The strength of each connection section is small and easy to deform, which is conducive to absorbing the bending stress generated when the shell connection part 152 is bent, thereby improving the problem of welding failure between the current collecting component 150 and the pole ear caused by the bending stress.

[0069] To improve welding efficiency, refer to Figure 12 to Figure 13 In an example of the secondary battery 100 of the utility model, the width of any one of the first notches 1521 is less than or equal to 0.2 mm, for example, it can be: 0.1 mm, 0.12 mm, 0.15 mm, 0.16 mm or 0.2 mm, etc. The shell connecting portion 152 and the surface of the rolling groove 114 facing the electrode assembly 120 are welded to form at least one second weld mark 1523, and each second weld mark 1523 is continuous and spans all the first notches 1521. That is, a continuous second weld mark 1523 is formed by welding the multiple connecting sections on the shell connecting portion 152 and the shell 110. The continuous second weld mark 1523 is conducive to improving the welding efficiency, and the width of any point of the first notch 1521 is limited to less than or equal to 0.2 mm, so that the first notch 1521 is formed into a narrow gap. Even if the second weld mark 1523 is welded across the first notch 1521, the first notch 1521 within the size range is conducive to being filled with molten material formed during welding, so as to reduce the situation where the shell 110 is welded through at the first notch 1521.

[0070] Considering that welding at the position of the first notch 1521 is not blocked by the shell connecting portion 152, there is a risk of welding through the shell 110. In an example of the secondary battery 100 of the utility model, preferably, the penetration of the second weld mark 1523 at the position of the first notch 1521 is less than 0.7 of the thickness of the shell 110. This setting can reduce the risk of welding through the shell 110.

[0071] In an example of the secondary battery 100 of the present invention, please refer to Figures 3 to 5Each shell connection part 152 is provided with a first notch 1521, the shape of the first notch 1521 is V-shaped, the top width a of the first notch 1521 is 1 mm, the root width b is 0.5 mm, the depth c is 2.5 mm, and the distance d from the outer periphery of the shell connection part 152 to the side of the current collector body 151 away from the electrode assembly 120 is 2.8 mm. The shell connection part 152 is divided into two connection ends by a first notch 1521, and each connection section and the shell 110 are welded separately, and two first weld marks 1522 arranged in sections are formed on the shell connection part 152.

[0072] In an example of the secondary battery 100 of the present invention, please refer to Figures 6 to 8 , two first notches 1521 are provided on each shell connection part 152. The shape of the first notch 1521 is V-shaped, the top width a of the first notch 1521 is 0.4 mm, the root width b is 0.2 mm, the depth c is 2.5 mm, and the distance d from the outer periphery of the shell connection part 152 to the side of the current collector body 151 away from the electrode assembly 120 is 3 mm. The shell connection part 152 is divided into three connection ends by the two first notches 1521, and each connection section is welded to the shell 110 separately, and three first weld marks 1522 arranged in sections are formed on the shell connection part 152.

[0073] In an example of the secondary battery 100 of the present invention, please refer to Figures 9 to 11 , three first notches 1521 are provided on each shell connection part 152, the shape of the first notch 1521 is V-shaped, the top width a of the first notch 1521 is 1 mm, the root width b is 0.2 mm, the depth c is 2 mm, and the distance d from the outer periphery of the shell connection part 152 to the side of the current collector body 151 away from the electrode assembly 120 is 3 mm. The shell connection part 152 is divided into four connection ends by the three first notches 1521, and each connection section is independently welded to the shell 110, and four first weld marks 1522 arranged in sections are formed on the shell connection part 152.

[0074] In an example of the secondary battery 100 of the present invention, please refer to Figure 12 to Figure 13 , three first notches 1521 are provided on each shell connection part 152, the shape of the first notch 1521 is rectangular, the top width a and the root width b of the first notch 1521 are the same, both are 0.1 mm, the depth c is 2 mm, and the distance d from the outer periphery of the shell connection part 152 to the side of the current collector body 151 away from the electrode assembly 120 is 3 mm. The shell connection part 152 and the shell 110 are continuously welded, and a second weld mark 1523 is formed on the shell connection part 152.

[0075] The above four embodiments have improved the technical problems in the prior art that the outer periphery of the shell connection part 152 cannot be bent smoothly and there is a large stress transfer, and the smoothness of the bending of the shell connection part 152 is achieved, and the reliability of the connection between the shell connection part 152 and the shell 110 is improved. At the same time, the bending stress of the shell connection part 152 is weakened, and the problem of welding failure between the current collecting component 150 and the pole ear caused by bending stress is improved.

[0076] See also Figures 3 to 13 In an example of the secondary battery 100 of the present invention, the shell connection portion 152 includes a bending portion 1524 connected to the current collecting body 151. Considering that the shell connection portion 152 is prone to generate deformation stress at the bending portion 1524 when bending, part of the deformation stress will be transmitted to the pole ear connection portion 153, causing a certain degree of damage to the pole ear connection portion 153. In severe cases, it may also cause the welding point between the current collecting component 150 and the pole ear to be pulled apart, thereby causing the risk of electrical connection failure of the electrode assembly 120. Furthermore, second notches 1525 are respectively provided on both sides of the bending portion 1524 along the circumference of the shell 110. The setting of the second notch 1525 can reduce the width of the bending portion 1524, thereby reducing the bending stress generated when the shell connecting portion 152 is bent. At the same time, the strength of the bending portion 1524 is reduced and it is easy to deform, which is beneficial to absorb the bending stress and weaken the transmission of the bending stress to the welding connection between the current collecting component 150 and the pole ear, thereby improving the problem of welding failure between the current collecting component 150 and the pole ear caused by bending stress.

[0077] See also Figure 3 , Figure 6 , Fig. 9 and Fig.12In an example of the secondary battery 100 of the utility model, the shell connecting portion 152 includes a bending portion 1524 connected to the current collecting body 151, and a weak portion 1526 extending along the circumference of the shell 110 is provided on the bending portion 1524. The weak portion 1526 can be provided at both ends or in the middle of the bending portion 1524, or can surround the entire circumference of the bending portion 1524. The weak portion 1526 can be in various forms, such as a combination of one or more of piers, notches or hollowing, as long as the bending strength of the bending portion 1524 can be weakened and the bending forming of the bending portion 1524 is facilitated. In this embodiment, the weak portion 1526 is a pier structure extending along the entire circumference of the bending portion 1524. The weak portion 1526 is provided on the bending portion 1524, which can weaken the stress generated by the shell connecting portion 152 when being bent. At the same time, due to the low strength of the weak portion 1526, under the action of stress, the weak portion 1526 of the bending portion 1524 is deformed first to reduce the transmission of stress to the welding connection portion between the current collecting component 150 and the pole lug, thereby improving the problem of welding failure between the current collecting component 150 and the pole lug caused by the bending stress. At the same time, the weak portion 1526 can also guide and position the bending of the bending portion 1524, improve the accuracy of the bending position of the bending portion 1524, and help improve the consistency of the assembly quality of the secondary battery 100. In addition, when the shell connecting portion 152 and the shell 110 are welded before the groove 114 is rolled, the weak portion 1526 can also be used as a reference line for the welding position, which is convenient for positioning the welding head during welding.

[0078] In an example of the secondary battery 100 of the present invention, the sum of the minimum flow areas of all weak parts 1526 is e, and the total area of ​​the welding wire formed by welding the current collecting body 151 and the tab is s, where e>s. It should be noted that the minimum flow area of ​​the weak parts 1526 is the minimum cross-sectional area of ​​each weak part 1526 along the circumference of the current collecting member 150, and the total area of ​​the welding wire refers to the projection area of ​​all the welding wires formed by welding the current collecting body 151 and the tab along the axial direction of the electrode assembly 120. The setting that the sum of the minimum flow areas e of all weak parts 1526 is greater than the total area s of the welding wire can weaken the transmission of bending stress without affecting the flow effect of the weak parts 1526.

[0079] See also Fig.14The utility model also provides a battery pack 10, the battery pack 10 includes any of the above-mentioned secondary batteries 100. In one embodiment of the battery pack 10 of the utility model, 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, connected in series or in parallel, or in a mixture of series and parallel. The box cover 102 is sealed on 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 utility model, the battery pack 10 may also include a battery pack 10 thermal management system, a circuit board and other parts. The battery pack 10 may be a battery module, a battery pack, an energy storage cabinet, etc.; they will not be described one by one here.

[0080] See also Fig.15 The utility model also provides an electronic device 1, which includes the above-mentioned battery pack 10. 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 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc., but is not limited to this. The working part 11 is a vehicle body, and the battery pack 10 is arranged at the bottom of the vehicle body, and provides power support for the driving of the vehicle or the operation of electrical components in the vehicle. However, in some other embodiments, the electronic device 1 can also be a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy and an electric tool, etc. Spacecraft include airplanes, rockets, space shuttles and spacecrafts, etc.; the working part 11 can be a unit component that can obtain the power of the battery pack 10 and perform corresponding work, such as a fan blade rotation unit, a vacuum cleaner dust removal unit, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The present application embodiment does not impose any special restrictions on the above-mentioned electronic device 1.

[0081] The utility model secondary battery is provided with a first notch at the outer periphery of the shell connection part. When the shell connection part is bent toward the shell axis, the outer periphery of the shell connection part is bent to a position with a smaller diameter. The provision of the first notch, on the one hand, reduces the area at the outer periphery of the shell connection part, reduces the generation of excess extrusion, and on the other hand, the first notch can also accommodate excess extrusion, improves the technical problem that the outer periphery of the shell connection part cannot be bent flat and there is a large stress transmission in the prior art, realizes the flatness of the bending of the shell connection part, improves the reliability of the connection between the shell connection part and the shell, and also weakens the bending stress of the shell connection part, improves the problem of welding failure between the current collecting component and the pole ear caused by the bending stress. Therefore, the utility model effectively overcomes some practical problems in the prior art and has a high utilization value and use significance. The above embodiments only illustrate the principle and effect of the utility model, and are not used to limit the utility model. Anyone familiar with this technology can modify or change the above embodiments without violating the spirit and scope of the utility model. Therefore, all equivalent modifications or changes made by those having ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A secondary battery, characterized in that: include: A shell, comprising a surrounding side wall, one end of the side wall is formed with an opening, and one end of the shell 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 current collecting component, comprising a current collecting body and a shell connecting portion connected to 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 outer periphery of the shell connecting portion facing the shell axis is provided with n first notches, where n≥1.

2. The secondary battery according to claim 1, characterized in that: The width of the root of the first notch is b, and the width of the top of the first notch is a, wherein 0.1 mm≤b≤a≤2 mm.

3. The secondary battery according to claim 2, characterized in that: Before the shell connecting portion is bent, the distance from the outer periphery of the shell connecting portion to the side of the current collector away from the electrode assembly is d, and the depth of the first notch is c, wherein 0.5d≤c <d。 4. The secondary battery according to claim 1, characterized in that: The current collecting component includes a plurality of the shell connecting parts, and the plurality of the shell connecting parts are arranged around the outer periphery of the current collecting body.

5. The secondary battery according to claim 4, characterized in that: Along the circumference of the shell, the shell connection portion is divided into n+1 connection segments by the first notch, and the shell connection portion and the rolling groove are welded on the surface of the electrode assembly facing greater than or equal to n+1 first weld marks, and each connection segment has at least one first weld mark.

6. The secondary battery according to claim 4, characterized in that: The width of any one of the first notches is less than or equal to 0.2 mm, and the shell connection portion and the surface of the rolling groove facing the electrode assembly are welded to form at least one second weld mark, and each of the second weld marks is continuous and spans all the first notches.

7. The secondary battery according to claim 6, characterized in that: The penetration depth of the second weld mark at the first notch position is less than 0.7 of the shell thickness.

8. The secondary battery according to claim 4, characterized in that: The shell connecting portion includes a bending portion connected to the current collecting body, and second notches are respectively arranged on both sides of the bending portion along the circumference of the shell.

9. The secondary battery according to claim 4, characterized in that: The shell connecting portion includes a bending portion connected to the current collecting body, and the bending portion is provided with a weak portion extending along the circumferential direction of the shell.

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

11. A battery pack, characterized in that: A secondary battery comprising the secondary battery according to any one of claims 1 to 10.

12. An electronic device, characterized in that: A battery pack comprising the battery pack of claim 11.

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