Secondary battery, battery pack, and electronic device
By staggering the housing connection part and the electrode connection part of the cylindrical battery, and using the through hole and the first weak part structure, the problem of welding failure between the current collecting member and the electrode during the mechanical sealing process is solved, and a more stable electrical connection is achieved.
Patent Information
- Application Number
- CN202421980879.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-15
- Publication Date
- 2025-06-03
- Estimated Expiration
- 2034-08-15
AI Technical Summary
During the mechanical sealing process of existing cylindrical batteries, welding between the current collecting members and the electrode ears is prone to failure, resulting in the risk of failure of the electrical connection of the electrode assembly.
By staggering the housing connection part and the pole ear connection part, and providing a through hole between the adjacent two pole ear connection parts, the width of the first connection part is reduced to weaken the bending stress transmission, and at the same time, the first weak part is provided in the straight section to absorb stress.
It effectively weakens the transmission of bending stress to the electrode connection part, improves the stability of welding between the current collecting member and the electrode, and avoids the risk of electrical connection failure.
Smart Images
Figure CN222940150U_ABST
Abstract
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 side wall 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 plurality of shell connecting parts surrounding and connected to the outer periphery of the current collecting body, the current collecting body comprises a plurality of pole ear connecting parts fixedly connected to the pole ear, the shell connecting part comprises a bent section bent toward the axis of the shell and a straight section connected to the current collecting body, and the bent section is welded to the surface of the rolling groove facing the electrode assembly; along the circumference of the shell, the shell connecting part is located between two adjacent pole ear connecting parts, a through hole is arranged between the two adjacent pole ear connecting parts, and a first connecting part is formed between each pole ear connecting part and the straight section.
[0005] In the above technical solution, along the circumference of the shell, the shell connection portion is located between two adjacent pole lug connection portions, so that the shell connection portion and the pole lug connection portion are staggered in the circumference of the shell. This arrangement can achieve that when the shell connection portion is bent, the bending stress is not directly acted on the pole lug connection portion when it is transmitted toward the current collecting body, so as to weaken the transmission of the bending stress to the pole lug connection portion.
[0006] In addition, through holes are provided between two adjacent tab connection parts, and first connection parts are formed between each tab connection part and the straight section. Due to the existence of the through holes, the width of the first connection parts is reduced, and the bending stress transmitted towards the tab connection parts can be weakened. At the same time, since the strength of the first connection parts is weakened, the first connection parts are prone to deformation under the action of the bending stress, absorbing part of the bending stress, and further weakening the transmission of the bending stress towards the tab connection parts, thereby improving the problem of welding failure between the current collector member and the tabs caused by the bending stress.
[0007] In an example of the secondary battery of the present utility model, a notch is provided between the straight section and the tab connection part, and the first connection part is located between the notch and the through hole.
[0008] In the above technical solution, the setting of the notch can further reduce the strength of the first connection part, making it more prone to deformation and absorbing more stress, ultimately further weakening the transmission of the bending stress towards the tab connection part.
[0009] In an example of the secondary battery of the present utility model, the sum of the minimum current-carrying areas of all the first connection parts is a, and the total area of the weld lines formed by welding the tab connection part and the tab is s, where a > s.
[0010] In the above technical solution, the minimum current-carrying area of the first connection part is the minimum at the cross-sectional area of each first connection part along the circumferential direction of the current collector member. The total area of the weld lines refers to the area of the projection of all the weld lines formed by welding the tab connection part and the tab along the axial direction of the electrode assembly. The setting that the sum a of the minimum current-carrying areas of all the first connection parts is greater than the total area of the weld lines can weaken the transmission of the bending stress while not affecting the current-carrying effect of the first connection parts.
[0011] In an example of the secondary battery of the present utility model, the straight section includes a first weak part.
[0012] In the above technical solution, by providing the first weak part on the straight section, the stress generated when the housing connection part is bent can be weakened. At the same time, since the strength of the first weak part is relatively low, under the action of the stress, the first weak part of the straight section deforms first, reducing the transmission of the stress towards the welded connection part between the current collector member and the tab, thereby improving the problem of welding failure between the current collector member and the tab caused by the bending stress.
[0013] In an example of the secondary battery of the present utility model, the first weak part includes one or more combinations of thinning, scoring, and hollowing.
[0014] In the above technical solution, one or more combinations of thinning, scoring, and hollowing can all achieve the effect of reducing the strength of the first weak part by reducing the cross-sectional area of the first weak part.
[0015] In an example of the secondary battery of the present utility model, the sum of the minimum current-carrying areas of all the first weak portions is b, and the total area of the welding lines formed by welding the current collector body and the tab is s, where b > s.
[0016] In the above technical solution, the minimum current-carrying area of the first weak portion is the minimum at the cross-sectional area of each first weak portion along the circumferential direction of the current collector member. The total area of the welding lines refers to the area of the projection along the axial direction of the electrode assembly of all the welding lines formed by connecting and welding the tab connection portions and the tabs. The setting where the sum b of the minimum current-carrying areas of all the first weak portions is greater than the total area of the welding lines can weaken the transmission of bending stress while not affecting the current-carrying effect of the first weak portions.
[0017] In an example of the secondary battery of the present utility model, both the upsetting and the scoring form grooves in the straight section, and the grooves are located on the side of the current collector body facing the electrode assembly.
[0018] In the above technical solution, the bending stress generated by the housing connection portion will cause the tab connection portion to warp. Similarly, at the first weak portion in the straight section, there is also a tendency to bulge in the direction away from the electrode assembly. If the groove is located on the side of the current collector body away from the electrode assembly, when the first weak portion bulges, there is a risk of breaking the first weak portion. Therefore, setting the groove on the side of the current collector body facing the electrode assembly can weaken the transmission of bending stress while reducing the risk of breakage at the first weak portion.
[0019] In an example of the secondary battery of the present utility model, a central hole is provided at the center of the current collector body. A second weak portion is included between each through hole and the central hole, and the second weak portion is configured to break when the internal pressure of the secondary battery exceeds a threshold value, so that the central hole and the through holes are communicated in the radial direction of the secondary battery.
[0020] In the above technical solution, when the internal pressure exceeds the threshold value, the second weak portion breaks, the central hole and the through holes are communicated, and the current collector body is divided into several thin sheets. Under the impact of the internal pressure, each thin sheet in the middle of the current collector body folds away from the electrode assembly, further reducing the blocking area, which helps the discharge of substances inside the secondary battery, thereby helping to prevent the secondary battery from exploding and improving the safety performance of the secondary battery.
[0021] The present utility model also provides a battery pack, which includes the secondary battery of any one of the above.
[0022] The present utility model also provides an electronic device, which includes the above battery pack.
[0023] For the secondary battery of the present utility model, in the circumferential direction of the housing, the housing connection part is located between two adjacent tab connection parts, so that the housing connection part and the tab connection part are staggeredly arranged in the circumferential direction of the housing. This arrangement can ensure that when the housing connection part is bent, the bending stress is not directly applied to the tab connection part when it is transmitted towards the current collector body, thereby weakening the bending stress transmitted towards the tab connection part.
[0024] In addition, a through hole is provided between two adjacent tab connection parts, and a first connection part is formed between each tab connection part and the straight section. Due to the existence of the through hole, the width of the first connection part is reduced, which can weaken the bending stress transmitted towards the tab connection part. At the same time, since the strength of the first connection part is weakened, the first connection part is prone to deformation under the action of the bending stress, absorbing part of the bending stress, and further weakening the transmission of the bending stress towards the tab connection part, thereby improving the problem of welding failure between the current collector component and the tab caused by the bending stress. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] 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 use in the description of 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.
[0026] Figure 1 It is a schematic diagram of the overall structure of an example of the secondary battery of the present utility model;
[0027] Figure 2 It is a schematic diagram of the electrode assembly structure of an example of the secondary battery of the present utility model;
[0028] Figure 3 It is a schematic diagram of the structure of the current collector component before bending in an embodiment of the secondary battery of the present utility model;
[0029] Figure 4 For Figure 3 It is a top view of the current collector component in
[0030] Figure 5 It is a schematic diagram of the structure of the current collector component before bending in a second embodiment of the secondary battery of the present utility model;
[0031] Figure 6 For Figure 5 It is a partial enlarged view of part A in
[0032] Figure 7 For Figure 5 It is a top view of the current collector component in
[0033] Figure 8 ForFigure 5 Bottom view of the middle current collector member;
[0034] Figure 9 Structural schematic diagram of the current collector member of three embodiments of the secondary battery of the present utility model before being bent;
[0035] Figure 10 is Figure 9 Top view of the middle current collector member;
[0036] Figure 11 Schematic diagram of an example of the battery pack of the present utility model;
[0037] Figure 12 Schematic diagram of an example of the electronic device of the present utility model.
[0038] Description of component numbers
[0039] 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 plate; 1211. Positive current collector; 1212. First coating area; 1213. First uncoated area; 122. Separator; 123. Negative electrode plate; 1231. Negative current collector; 1232. Second coating area; 1233. Second uncoated area; 124. Negative electrode tab; 125. Positive electrode tab; 130. Cover plate; 140. Terminal; 150. Current collector member; 151. Current collector body; 152. Shell connection part; 1521. Bent section; 1522. Straight section; 1523. First weak part; 1524. Groove; 153. Tab connection part; 154. Through hole; 155. First connection part; 156. Notch; 157. Central hole; 158. Second weak part. Detailed implementation manners
[0040] The following uses specific specific examples to illustrate the implementation manners 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 implementation manners. The 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 specific implementation manners, rather than for 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.
[0041] 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 method, device, and material similar or equivalent to the prior art in the methods, devices, and materials of the embodiments of the present utility model can also be used to implement the present utility model.
[0042] 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 used 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.
[0043] The secondary battery includes an electrode assembly, which is a component in the secondary battery where an electrochemical reaction occurs, and may include one or more electrode assemblies.
[0044] 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. The terminal post passes through the end wall and is electrically connected to the electrode assembly to conduct the electric energy generated by the electrode assembly.
[0045] The mainstream packaging method of existing secondary batteries is mechanical sealing. Mechanical sealing has the advantages of mature technology and equipment and fast production rhythm, and is widely used. The current collector member is electrically connected to both the electrode assembly and the housing at the same time 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.
[0046] There are various connection methods between the current collector member and the housing. A common one is: a housing connection part is provided at the edge of the current collector member. First, the housing connection part is welded and fixed to the side wall of the housing, and then a rolling groove is rolled on the side wall to make the housing connection part continue to bend towards the axis of the housing. However, the inventor found that when the housing connection part 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.
[0047] In view of this, the utility model provides a technical solution, in which the shell connection part and the pole lug connection part are staggered in the circumferential direction of the shell. This arrangement can ensure that when the shell connection part is bent, the bending stress is not directly acted on the pole lug connection part when it is transmitted toward the current collecting body, so as to weaken the bending stress transmitted to the pole lug connection part, thereby improving the problem of welding failure between the current collecting component and the pole lug caused by the bending stress.
[0048] See also Figures 1 to 12 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 .
[0049] 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.
[0050] See also Figures 1 to 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.
[0051] See also 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.
[0052] 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.
[0053] 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, or 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.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] See also Figure 1, A current collector member 150 is disposed between the electrode assembly 120 and the cover plate 130. The housing 110 and the electrode assembly 120 are electrically connected through the current collector member 150. Specifically, the current collector member 150 includes a current collector body 151 and a housing connection portion 152 connected to the outer peripheral edge of the current collector body 151. The housing connection portion 152 can be an integral annular structure or one or more fan-shaped annular structures, as long as the current guiding requirements and welding strength requirements between the current collector member 150 and the housing 110 are satisfied. The housing connection portion 152 includes a bent section 1521 that bends towards the axis of the housing 110 and a straight section 1522 connected to the current collector body 151. Before the rolling groove 114 of the housing 110 is rolled, the bent section 1521 is first welded to the side wall 112 of the housing 110. While rolling the groove 114, the bent section 1521 welded to the housing 110 continues to bend towards the axis of the housing 110, and finally forms a bend towards the axis of the housing 110 and is welded to the surface of the rolling groove 114 facing the electrode assembly 120.
[0058] Please refer to Figures 3 to 5 and Figure 7 and Figure 10 , The current collector body 151 is fixedly connected to the tab. There are various ways to connect the current collector body 151 and the tab. For example, it can be a welded connection or a conductive adhesive bonding connection, etc. As long as the electrical connection between the current collector member 150 and the tab can be achieved and the current guiding requirements are satisfied. In this embodiment, a welded connection is adopted. Further, the current collector body 151 includes a plurality of tab connection portions 153 welded to the tab. The number, shape, and position of the tab connection portions 153 are not limited. Preferably, in this embodiment, the current collector body 151 includes four tab connection portions 153 welded to the tab. The four tab connection portions 153 are evenly arranged in an array along the circumferential direction of the current collector body 151. This setting can make the welding balance stability between the current collector member 150 and the tab better, and have a more uniform current guiding effect, thereby improving the stability of current guiding between the housing 110 and the electrode assembly 120.
[0059] Considering the technical problem 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 be transmitted into the current collector member 150, resulting in the warping inside the current collector member 150. Please refer to Figures 3 to 5 and Figure 7 and Figure 10 , Along the circumferential direction of the housing 110, the housing connection portion 152 is located between two adjacent tab connection portions 153, so that the housing connection portion 152 and the tab connection portion 153 are staggered in the circumferential direction of the housing 110. This setting can achieve that when the housing connection portion 152 bends, the bending stress is not directly applied to the tab connection portion 153 when it is transmitted towards the current collector body 151, so as to weaken the transmission of the bending stress towards the tab connection portion 153.
[0060] Please refer to Figures 3 to 5 and Figure 7 and Figure 10 Further, a through hole 154 is provided between two adjacent tab connection portions 153. The shape of the through hole 154 is not limited and can be circular, square, fan-shaped, diamond-shaped or other irregular shapes. A first connection portion 155 is formed between each tab connection portion 153 and the straight section 1522. The shape of the first connection portion 155 depends on the shape of the through hole 154. Due to the presence of the through hole 154, the width of the first connection portion 155 is reduced, which can weaken the bending stress transmitted to the tab connection portion 153. At the same time, since the strength of the first connection portion 155 is weakened, the first connection portion 155 is prone to deformation under the action of the bending stress, absorbing part of the bending stress, and can further weaken the transmission of the bending stress to the tab connection portion 153, thereby improving the problem of welding failure between the current collector member 150 and the tab caused by the bending stress.
[0061] Please refer to Figures 3 to 5 and Figure 7 and Figure 10 In an example of the secondary battery 100 of the present invention, a notch 156 is provided between the straight section 1522 and the tab connection portion 153. The first connection portion 155 is located between the notch 156 and the through hole 154. The shape of the notch 156 has various forms, such as rectangular, fan-shaped or other irregular shapes, and is not limited thereto. The provision of the notch 156 can further reduce the strength of the first connection portion 155, making it more likely to deform and absorb more stress, and ultimately further weakening the transmission of the bending stress to the tab connection portion 153.
[0062] Please refer to Figures 3 to 5 and Figure 7 and Figure 10 In an example of the secondary battery 100 of the present invention, the sum of the minimum current-carrying areas of all the first connection portions 155 is a, and the total area of the welding lines formed by welding the tab connection portion 153 and the tab is s, where a > s. The minimum current-carrying area of the first connection portion 155 is the minimum of the cross-sectional areas of each first connection portion 155 along the circumferential direction of the current collector member 150. The total area of the welding lines refers to the area of the projection of all the welding lines formed by welding the tab connection portion 153 and the tab along the axial direction of the electrode assembly 120. The setting that the sum a of the minimum current-carrying areas of all the first connection portions 155 is greater than the total area of the welding lines can weaken the transmission of the bending stress without affecting the current-carrying effect of the first connection portion 155.
[0063] Please refer to Figures 5 to 8, in an example of the secondary battery 100 of the present utility model, the straight section 1522 includes a first weak part 1523. This setting can weaken the stress generated when the housing connection part 152 is bent. At the same time, since the strength of the first weak part 1523 is relatively low, under the action of stress, the first weak part 1523 of the straight section 1522 deforms first, so as to reduce the transmission of stress towards the current collector member 150 and the welding connection part of the tab, thereby improving the problem of welding failure between the current collector member 150 and the tab caused by bending stress.
[0064] Please refer to Figures 5 to 8 , in an example of the secondary battery 100 of the present utility model, the first weak part 1523 includes one or a combination of thinning, scoring, and hollowing. In some embodiments, only thinning, scoring, or hollowing is provided. In some other embodiments, a combination of thinning and hollowing, or a combination of scoring and hollowing can be provided. As long as the cross-sectional area of the first weak part 1523 can be reduced and the strength of the first weak part 1523 can be weakened to facilitate the bending of the straight section 1522 at the first weak part 1523, no matter which of the above forms, the effect of reducing the strength of the first weak part 1523 can be achieved by reducing the cross-sectional area of the first weak part 1523.
[0065] Please refer to Figures 5 to 8 , in an example of the secondary battery 100 of the present utility model, the minimum current-carrying area of all the first weak parts 1523 is b, and the total area of the welding lines formed by welding the current collector body 151 and the tab is s, where b > s. It should be noted that the minimum current-carrying area of the first weak part 1523 is the minimum of the cross-sectional areas of each first weak part 1523 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 welding lines formed by welding the tab connection part 153 and the tab along the axial direction of the electrode assembly 120. The setting that the sum b of the minimum current-carrying areas of all the first weak parts 1523 is greater than the total area s of the welding lines can weaken the transmission of bending stress without affecting the current-carrying effect of the first weak part 1523.
[0066] Please refer to Figures 5 to 8, in an example of the secondary battery 100 of the present utility model, both the thinning and the scoring form a groove 1524 in the straight section 1522. Considering that the bending stress generated by the housing connection portion 152 may cause the warping of the tab connection portion 153. Similarly, there is also a tendency to bulge away from the electrode assembly 120 at the first weak portion 1523 of the straight section 1522. If the groove 1524 is located on the side of the current collector body 151 away from the electrode assembly 120, when the first weak portion 1523 bulges, there is a risk of breaking the first weak portion 1523. Preferably, in this embodiment, the groove 1524 is located on the side of the current collector body 151 facing the electrode assembly 120. This setting can weaken the transmission of the bending stress while reducing the risk of breaking at the first weak portion 1523.
[0067] Please refer to Figures 3 to 4 , in an example of the secondary battery 100 of the present utility model, a central hole 157 is provided at the center of the current collector body 151. The shape of the central hole 157 is not limited and can be a round hole, a square hole, a diamond hole, a polygonal hole or a hole with other irregular closed contours. Each through hole 154 and the central hole 157 include a second weak portion 158. The second weak portion 158 is configured to break when the internal pressure of the secondary battery 100 exceeds a threshold value, so that the central hole 157 and the through hole 154 communicate in the radial direction of the secondary battery 100. The second weak portion 158 can be in various forms. For example, it can be a scoring, thinning or hollow structure provided between the through hole 154 and the central hole 157. The hollow structure can be one or more diamond holes, oval holes, round holes or rectangular holes, etc., which are not limited as long as they can weaken the strength of the connection part between the through hole 154 and the central hole 157 and can break when the internal pressure of the secondary battery 100 exceeds the threshold value. After the second weak portion 158 breaks, the central hole 157 and the through hole 154 are connected, and the current collector body 151 is divided into several thin sheets. Under the impact of the internal pressure, each thin sheet in the middle of the current collector body 151 folds away from the electrode assembly 120, further reducing the blocking area, which helps the discharge of the substances inside the secondary battery and thus helps prevent the secondary battery 100 from exploding and improves the safety performance of the secondary battery 100.
[0068] In an embodiment of the secondary battery 100 of the present utility model, please refer to Figures 3 to 4, in this embodiment, the current collector member 150 includes four housing connection portions 152 and four tab connection portions 153. The four tab connection portions 153 are evenly distributed in a circumferential array along the circumference of the current collector body 151. Along the circumference of the current collector body 151, one housing connection portion 152 is provided between every two adjacent tab connection portions 153. A through hole 154 is provided between every two adjacent tab connection portions 153. The shape of the through hole 154 is similar to a vase shape that is thinner in the middle. The through hole 154 includes a larger trapezoidal portion near the central hole 157, a hyperbolic portion of the avoidance notch 156, and a smaller trapezoidal portion near the housing connection portion 152. A notch 156 is provided between each straight section 1522 and each tab connection portion 153. The notch 156 is a rectangular opening 113. Under the combined influence of the shape of the notch 156 and the through hole 154, the first connection portion 155 forms a shape similar to a U shape. The first connection portion 155 of this shape has a larger length and a narrower width, and is more likely to deform under the action of bending stress. A second weak portion 158 is provided between each through hole 154 and the central hole 157. The shape of the second weak portion 158 is an oval hole, and the extension line of the long side of the oval can connect the through hole 154 and the central hole 157. When the internal pressure reaches the threshold value, it can tear and connect the central hole 157 and the through hole 154.
[0069] In the second embodiment of the secondary battery 100 of the present utility model, please refer to Figures 5 to 8 , the difference between this embodiment and the first embodiment is that the through hole 154 lacks the trapezoidal portion near the housing connection portion 152. The notch 156 is enlarged toward the tab connection portion 153 on the basis of the first embodiment, and the shape is fan-shaped. This setting has little change in the length of the first connection portion 155. However, since the through hole 154 lacks the trapezoidal portion near the housing connection portion 152, the area of the straight section 1522 becomes larger. Therefore, a first weak portion 1523 can be provided on the straight section 1522 to weaken the transmission of the bending stress toward the inside of the current collector body 151. Preferably, in this embodiment, the first weak portion 1523 is provided as a thinning structure, and the opening 113 of the groove 1524 formed by the thinning structure faces the side of the electrode assembly 120. This setting can reduce the risk of breakage at the first weak portion 1523 while weakening the transmission of the bending stress.
[0070] In the third embodiment of the secondary battery 100 of the present utility model, please refer to Figures 9 to 10, the difference between this embodiment and an embodiment lies in that the shape of the through hole 154 is different. The through hole 154 includes a triangular part near the central hole 157 and a rectangular part near the housing connection part 152. The area of the through hole 154 set in this way is increased, and the pressure relief and heat dissipation effects are better. There is no notch 156 provided between the straight section 1522 and the tab connection part 153. However, the enlargement of the through hole 154 enables the first connection part 155 to still have the effect of being easily deformed. There is no second weak part 158 provided between the central hole 157 and the through hole 154. However, the part near the central hole 157 is the tip of the triangle, and the distance between the edge of the through hole 154 and the central hole 157 is also smaller than that in an embodiment. Therefore, when the internal pressure of the secondary battery 100 reaches the threshold value, the through hole 154 and the central hole 157 are still easily torn to communicate with each other.
[0071] Please refer to Figure 11 , the present invention also provides 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 invention, 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 in a mixed connection of series and parallel. 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 invention, 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 are not elaborated here one by one.
[0072] Please refer to Figure 12The 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.
[0073] In the secondary battery of the utility model, along the circumference of the shell, the shell connection part is located between two adjacent pole lug connection parts, so that the shell connection part and the pole lug connection part are staggered in the circumference of the shell. This arrangement can achieve that when the shell connection part is bent, the bending stress is not directly applied to the pole lug connection part when it is transmitted toward the current collecting body, so as to achieve the effect of weakening the bending stress transmitted toward the pole lug connection part. A through hole is arranged between two adjacent pole lug connection parts, and a first connection part is formed between each pole lug connection part and the straight section. Due to the existence of the through hole, the width of the first connection part is reduced, which can weaken the bending stress transmitted toward the pole lug connection part, and absorb part of the bending stress by deformation, which can further weaken the transmission of the bending stress toward the pole lug connection part, thereby improving the problem of welding failure between the current collecting component and the pole lug caused by the bending stress. Therefore, the utility model effectively overcomes some practical problems in the prior art and has 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 the technology can modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the relevant 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: 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 current collecting member, comprising a current collecting body and a plurality of shell connecting parts connected around the outer periphery of the current collecting body, wherein the current collecting body comprises a plurality of pole tab connecting parts fixedly connected to the pole tabs, the shell connecting part comprises a bent section bent toward the axis of the shell and a straight section connected to the current collecting body, and the bent section is welded to a surface of the rolling groove facing the electrode assembly; Wherein, along the circumference of the shell, the shell connection portion is located between two adjacent pole lug connection portions, a through hole is provided between the two adjacent pole lug connection portions, and a first connection portion is formed between each pole lug connection portion and the straight section.
2. The secondary battery according to claim 1, characterized in that: A gap is provided between the straight section and the tab connecting portion, and the first connecting portion is located between the gap and the through hole.
3. The secondary battery according to claim 2, characterized in that: The sum of the minimum flow areas of all the first connection parts is a, and the total area of the electrode tab connection part and the welding line formed by welding the electrode tab is s, wherein a>s.
4. The secondary battery according to claim 1, characterized in that: The straight section includes a first weakened portion.
5. The secondary battery according to claim 4, characterized in that: The first weak portion includes one or more combinations of thinning, notching and hollowing.
6. The secondary battery according to claim 5, characterized in that: The sum of the minimum flow areas of all the first weak parts is b, and the total area of the welding line formed by welding the current collecting body and the tab is s, wherein b>s.
7. The secondary battery according to claim 5, characterized in that: The thinning and notching both form a groove in the straight section, and the groove is located on a side of the current collecting body facing the electrode assembly.
8. The secondary battery according to claim 1, characterized in that: A central hole is provided at the center of the current collecting body, and a second weak portion is included between each of the through holes and the central hole, and the second weak portion is configured to break when the internal pressure of the secondary battery exceeds a threshold value so that the central hole and the through hole are connected in the radial direction of the secondary battery.
9. A battery pack, characterized in that: A secondary battery comprising the secondary battery according to any one of claims 1 to 8.
10. An electronic device, characterized in that: A battery pack comprising the battery pack of claim 9.