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 first current collecting component, the shell comprises a first end wall, a second end wall and a side wall; the electrode assembly is accommodated in the shell, the electrode assembly comprises a winding structure formed by laminating and winding a first pole piece, a second pole piece and a diaphragm, and the end part of the first pole piece comprises a first pole lug; the first current collecting component is welded with the first tab and forms at least one group of first welding marks, and the first current collecting component is welded with the shell and forms at least one group of second welding marks; tangent lines are made from the center of the first current collecting component to the two sides of the first welding mark to define first fan-shaped areas, tangent lines are made from the center of the first current collecting component to the two sides of the second welding mark to define second fan-shaped areas, and each first fan-shaped area and at least one second fan-shaped area at least partially coincide; the technical problem that the length of a current transmission path between a tab and a shell is uncontrollable can be solved.

Description

Technical Field

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

[0002] With the development of new energy technologies, secondary batteries are increasingly widely used, such as in mobile phones, laptop computers, battery cars, electric vehicles, electric airplanes, electric ships, electric toy cars, etc.

[0003] The electrical connection relationship between the housing and the tab of a secondary battery is usually that the tab is first welded to a current collector member, and then the current collector member is welded to the housing. In the prior art, blind welding is usually used when welding the current collector member and the housing, and it is difficult to ensure the length of the current transmission path between the tab and the housing. Therefore, optimizing the positional relationship between the weld mark between the tab and the current collector member and the weld mark between the current collector member and the housing, and reducing the current transmission path from the tab to the housing, are important problems that need to be overcome to improve the overall performance of the secondary battery. Summary of the Utility Model

[0004] The utility model provides a secondary battery, a battery pack and an electronic device to improve the technical problem of uncontrollable length of the current transmission path between the tab and the housing.

[0005] To achieve the above object and other related objects, the utility model provides a secondary battery, a battery pack and an electronic device. The secondary battery includes: a housing, an electrode assembly and a first current collector member; the housing includes a first end wall and a second end wall arranged opposite to each other, and a side wall surrounding the first end wall and the second end wall; the electrode assembly is accommodated in the housing, and the electrode assembly includes a winding structure formed by laminating and winding a first electrode plate, a second electrode plate and a separator layer. The end of the first electrode plate includes a first tab formed by extending out of the separator along the winding axis direction of the electrode assembly and bending; the first current collector member is welded to the first tab and forms at least one group of first weld marks, and the first current collector member is welded to the housing and forms at least one group of second weld marks; wherein, tangents are respectively made from the center of the first current collector member to both sides along the circumferential direction of the first current collector member to the first weld mark to enclose a first sector region, and tangents are respectively made from the center of the first current collector member to both sides along the circumferential direction of the first current collector member to the second weld mark to enclose a second sector region, and each first sector region and at least one second sector region at least partially overlap.

[0006] In the above technical solution, the shortest path for current transmission from the first tab to the housing is to reach the housing along the radial direction of the current collector member. Therefore, in order to achieve a short current transmission path between the first weld mark formed by welding the first current collector member and the first tab and the second weld mark formed by welding the first current collector member and the housing, it is defined that along the circumferential direction of the first current collector member, by respectively making tangents from the center of the first current collector member to both sides of the first weld mark along the circumferential direction of the first current collector member to enclose a first sector area, and by respectively making tangents from the center of the first current collector member to both sides of the second weld mark along the circumferential direction of the first current collector member to enclose a second sector area. Each first sector area and at least one second sector area at least partially overlap. The first weld mark located in the overlapping part can reach the second weld mark along the radial direction of the current collector member, so that each first weld mark has the shortest current transmission path, thereby improving the technical problem that the length of the current transmission path between the first tab and the housing is uncontrollable, and further achieving beneficial effects such as improving the current transmission efficiency, reducing the internal resistance, enhancing the heat dissipation performance, and improving the battery cycle life, etc., to improve the comprehensive performance of the secondary battery.

[0007] In an example of the secondary battery of the present utility model, there are n groups of first weld marks, n≥2, and the n groups of first weld marks are distributed along the circumferential direction of the first current collector member. The central angle corresponding to the coverage area of each group of first weld marks is α i (i = 1~n), and the sum of the central angles corresponding to the coverage areas of the n groups of first weld marks is There are m groups of second weld marks, m≥1, and the m groups of second weld marks are distributed along the circumferential direction of the first current collector member. The central angle corresponding to the coverage area of each group of second weld marks is β j (j = 1~m), and the sum of the central angles corresponding to the coverage areas of the m groups of second weld marks is Wherein,

[0008] In the above technical solution, considering that in actual assembly, the worst extreme state of the positional relationship between the first weld mark and the second weld mark is that along the circumferential direction of the first current collector member, the second weld mark just falls between two adjacent first weld marks. At this time, there is no overlapping part between the first sector area and the second sector area. Therefore, in this technical solution, the central angle α i and the central angle β j are defined, and the relationship between the central angle α i and the central angle β j is further limited as: This setting can achieve that even when the positional relationship between the first weld mark and the second weld mark is in the worst extreme state, each first sector area and at least one second sector area can at least partially overlap.

[0009] In an example of the secondary battery of the present utility model, the first current collector member is welded to the first end wall to form a second weld mark, wherein,

[0010] In the above technical solution, the structural form is that the first current collecting member is welded to the first end wall. In this structural form, the longer the length of the second weld mark, the more unfavorable it is to the strength of the structure of the first end wall. Especially when the second weld mark forms a complete closed shape on the first end wall, a weak structure will be formed, resulting in the first end wall being prone to cracking. Therefore, the limitation of [[ID=]] can achieve that the second weld mark is less than one circle along the circumferential direction of the first current collecting member, which is beneficial to improving the structural strength of the first end wall.

[0011] In an example of the secondary battery of the present utility model, and

[0012] In the above technical solution, the limitation of [[ID=]] can achieve that the first weld mark will weld more first tab numbers along the circumferential direction of the first current collecting member, which can play the role of reducing the internal resistance. And because the current-carrying capacity per unit length of the second weld mark is greater than that of the first weld mark, therefore, setting can achieve that while ensuring that the second weld mark and the first weld mark have a matching current-carrying capacity, the length of the second weld mark is as small as possible, which is beneficial to improving the structural strength of the first end wall.

[0013] In an example of the secondary battery of the present utility model, n groups of first weld marks are evenly distributed along the circumferential direction of the first current collecting member. The central angles formed by connecting the centers of the first current collecting member with the points closest to the center of the first current collecting member for each adjacent two groups of first weld marks are γ, where γ ≤ 120°.

[0014] In the above technical solution, n groups of first weld marks are evenly distributed along the circumferential direction of the first current collecting member, which is beneficial to the uniform distribution of current between the first current collecting member and the first tab, so as to reduce the overheating problem caused by too high local current density. At the same time, it helps to maintain the consistency of the secondary battery to improve the production efficiency. Limiting the central angle γ to γ ≤ 120° can achieve that there are at least 3 groups of first weld marks along the circumferential direction of the first current collecting member. The more first weld marks there are, the more first tabs are connected, which is beneficial to reducing the battery internal resistance, improving the current-carrying capacity, reducing heat generation, and improving the comprehensive performance of the secondary battery.

[0015] In an example of the secondary battery of the present utility model, the central angles formed by making tangents from the center of the first current collecting member to the outermost points on the adjacent sides of each adjacent two groups of first weld marks are δ, where δ ≤ 90°.

[0016] In the above technical solution, a central angle δ is defined, and it is further limited that δ ≤ 90°. This setting can achieve a relatively large span of the first weld mark in the circumferential direction of the first current collector member, further increasing the number of first tabs welded to the first weld mark, which is beneficial to reducing the internal resistance of the battery, improving the overcurrent capacity of the current, reducing heat generation, and further improving the comprehensive performance of the secondary battery.

[0017] In an example of the secondary battery of the present utility model, along the radial direction of the first current collector member, the maximum distance from the first weld mark to the center of the first current collector member is R1, and the maximum distance from the second weld mark to the center of the first current collector member is R2, where R2 - R1 ≤ 10 mm.

[0018] In the above technical solution, it is limited that R2 - R1 ≤ 10 mm, that is, the maximum distance between the first weld mark and the second weld mark is limited to be less than 10 mm. This setting enables a smaller distance between the first weld mark and the second weld mark, which can reduce the resistance between the first weld mark and the second weld mark, improve the overcurrent capacity of the current, reduce heat generation, and further improve the comprehensive performance of the secondary battery. Additionally, this limitation can keep a safe distance between the second weld mark and the tab cutting area at the outer edge of the first tab, preventing the diaphragm from being scalded during the welding of the second weld mark and reducing the risk of internal short circuit in the secondary battery.

[0019] In an example of the secondary battery of the present utility model, along the radial direction of the first current collector member, the minimum distance from the first weld mark to the center of the first current collector member is R3, and the radius of the outer peripheral edge of the first current collector member is R4, where 0.2R4 ≤ R3 < R1 ≤ 0.9R4.

[0020] In the above technical solution, the area corresponding to 0.2R4 to 0.9R4 of the first tab is the area where the number of tab layers is relatively stable. The number of tab layers in this area is the largest and relatively uniform. Distributing the first weld mark in the stable area of the stacked number of the first tab can achieve the effect of connecting more layers with the first tab and is not easily welded through, so as to play the role of reducing internal resistance, improving conductivity, safety, and energy density, etc., to improve the battery performance.

[0021] In an example of the secondary battery of the present utility model, along the radial direction of the first current collector member, the winding structure includes a winding hole with a radius of R6, where R3 - R6 ≤ 10 mm.

[0022] In the above technical solution, the setting of R3 - R6 ≤ 10 mm can be understood as the distance from the position where the first weld mark is closest to the center of the first current collector member to the inner peripheral edge of the winding structure is less than or equal to 10 mm. This setting enables a relatively close distance between the first weld mark and the inner peripheral edge of the winding structure, which can achieve the effect of increasing the number of turns connected to the first tab, and further play the role of reducing internal resistance, improving conductivity, safety, and energy density, etc., to improve the battery performance.

[0023] In an example of the secondary battery of the present utility model, along the radial direction of the first current collector member, the radius of the winding structure is R5, where R5 - R1 ≤ 10 mm.

[0024] In the above technical solution, the setting of R5 - R1 ≤ 10 mm can be understood as the distance from the position where the first welding mark is farthest from the center of the first current collector member to the outer peripheral edge of the winding structure is less than or equal to 10 mm. This setting makes the first welding mark have a relatively close distance to the outer peripheral edge of the winding structure. On the one hand, it can achieve the effect of increasing the number of turns connected to the first pole ear. On the other hand, since the single-turn length of the winding structure is larger closer to the outer peripheral edge, the effect of reducing the internal resistance and improving the battery performance when the first welding mark increases the number of connection turns at the position close to the outer peripheral edge is more prominent.

[0025] In an example of the secondary battery of the present utility model, along the axial direction of the first current collector member, the first current collector member at least covers part of the first pole ear located at the outermost side of the winding structure.

[0026] In the above technical solution, at least part of the first pole ear located at the outermost side can be covered and pressed by the first current collector member, which can effectively prevent the first pole ear from warping, so as to reduce the risk of the first pole ear breaking and falling into the interior of the housing under the action of external force and causing a short circuit.

[0027] The present utility model also provides a battery pack, which includes the secondary battery of any one of the above.

[0028] The present utility model also provides an electronic device, which includes the above battery pack.

[0029] In the secondary battery of the present utility model, since the shortest path for current transmission from the first pole ear to the housing is along the radial direction of the current collector member to the housing, in order to make the first welding mark formed by welding the first current collector member and the first pole ear and the second welding mark formed by welding the first current collector member and the housing have a shorter current transmission path, it is defined that along the circumferential direction of the first current collector member, by respectively making tangents from the center of the first current collector member to both sides of the first welding mark along the circumferential direction of the first current collector member to enclose a first sector area, and by respectively making tangents from the center of the first current collector member to both sides of the second welding mark along the circumferential direction of the first current collector member to enclose a second sector area, at least part of each first sector area and at least one second sector area overlap, and the first welding mark located in the overlapping part can reach the second welding mark along the radial direction of the current collector member, having the shortest current transmission path, so as to improve the technical problem that the length of the current transmission path between the first pole ear and the housing is uncontrollable, and further achieve the beneficial effects of improving the current transmission efficiency, reducing the internal resistance, enhancing the heat dissipation performance, improving the battery cycle life, etc., and improving the comprehensive performance of the secondary battery. Description of the Drawings

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other embodiments can be obtained based on these drawings.

[0031] Figure 1 Schematic diagram of the overall structure of an example of a secondary battery of the present invention;

[0032] Figure 2 Schematic diagram of the electrode assembly structure of an example of a secondary battery of the present invention;

[0033] Figure 3 Schematic diagram of the welding of the first current collector member and the electrode assembly of an example of a secondary battery of the present invention;

[0034] Figure 4 Schematic diagram of the welding of the first current collector member and the electrode assembly of an example of a secondary battery of the present invention;

[0035] Figure 5 Schematic diagram of the welding of the first current collector member and the electrode assembly of another example of a secondary battery of the present invention;

[0036] Figure 6 Schematic diagram of the welding of the first current collector member and the electrode assembly of another example of a secondary battery of the present invention;

[0037] Figure 7 Schematic diagram of the welding of the first current collector member and the electrode assembly of yet another example of a secondary battery of the present invention;

[0038] Figure 8 Schematic diagram of the welding of the first current collector member and the electrode assembly of yet another example of a secondary battery of the present invention;

[0039] Figure 9 Schematic diagram of an example of a battery pack of the present invention;

[0040] Figure 10 Schematic diagram of an example of an electronic device of the present invention.

[0041] Element reference numeral description

[0042] 1. Electronic device; 10. Battery pack; 11. Working part; 101. Box body; 102. Box cover; 100. Secondary battery; 110. Housing; 111. Second end wall; 112. Side wall; 113. Opening; 114. First end wall; 120. Electrode assembly; 121. Second electrode plate; 1211. Positive current collector; 1212. Second coating area; 1213. Second uncoated area; 122. Separator; 123. First electrode plate; 1231. Negative current collector; 1232. First coating area; 1233. First uncoated area; 124. First tab; 125. Second tab; 126. Winding structure; 127. Winding hole; 130. Terminal; 140. First current collecting member; 141. First welding mark; 142. Second welding mark; 150. Second current collecting member. Detailed implementation manners

[0043] 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. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. It should also be understood that the terms used in the embodiments of the present utility model are for 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 according to conventional conditions or according to the conditions recommended by each manufacturer.

[0044] When the embodiments give a numerical range, it should be understood that unless otherwise specified in the present utility model, any value between the two endpoints of each numerical range and any one of the values 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 prior art and the description of the present utility model, can also use any methods, devices and materials of the prior art similar or equivalent to the methods, devices and materials in the embodiments of the present utility model to implement the present utility model.

[0045] 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 for limiting the scope of implementation of the present utility model. The change or adjustment of their relative relationship, without substantial change in technical content, should also be regarded as the scope of implementation of the present utility model.

[0046] The secondary battery includes a housing and an electrode assembly. The electrode assembly is accommodated in the housing, and the electrode assembly is the component in the secondary battery where an electrochemical reaction occurs. The housing can contain one or more electrode assemblies.

[0047] An electrode assembly is primarily formed by winding or stacking positive and negative electrode sheets, with a separator typically positioned between them. The positive electrode sheet includes a positive current collector and a positive active material, with the positive active material coated on the surface of the positive current collector. The positive current collector includes a coated area coated with the active material and a bare foil area uncoated with the active material, which, when wound, forms the positive electrode tab of the electrode assembly. The negative electrode sheet includes a negative current collector and a negative active material, with the negative active material coated on the surface of the negative current collector. The negative current collector includes a coated area coated with the active material and a bare foil area uncoated with the active material, which, when wound, forms the negative electrode tab of the electrode assembly.

[0048] The secondary battery also includes an electrode post and a first current collecting member. The casing includes first and second end walls arranged opposite each other, and a side wall surrounding the first and second end walls. One end of the side wall has an opening, through which the electrode assembly can be assembled into the casing. The first end wall is used to cover the casing opening to achieve a seal. The electrode post passes through the second end wall to electrically connect to the electrode assembly to conduct the electricity generated by the electrode assembly. The first current collecting member is welded to the negative electrode tab, forming a first weld mark. The first current collecting member is welded to the casing, forming a second weld mark.

[0049] However, the inventors discovered that in existing secondary batteries, after the tabs are first welded to the current collecting components, and then the current collecting components are welded to the shell, since the secondary battery is in a rotating state on the production line and the first end wall cover and the rear cover block the first weld mark, it is impossible to accurately locate the position between the second weld mark and the first weld mark, that is, the blind welding mentioned above. This welding method makes it difficult to ensure the length of the current transmission path between the tabs and the shell, which will affect the various performances of the secondary battery.

[0050] In view of this, the present invention provides a technical solution, wherein along the circumference of the first current collecting component, the first fan-shaped area corresponding to each first weld mark and the second fan-shaped area corresponding to at least one second weld mark at least partially overlap, and the first weld mark located in the above-mentioned overlapping part can reach the second weld mark along the radial direction of the current collecting component, and has the shortest current transmission path, so as to improve the technical problem of uncontrollable length of the current transmission path between the first electrode ear and the shell.

[0051] See also Figures 1 to 10 The present invention provides a secondary battery 100 , which includes a housing 110 , an electrode assembly 120 , a terminal post 130 , a first current collecting member 140 , and a second current collecting member 150 .

[0052] The housing 110 includes a first end wall 114 and a second end wall 111 that are oppositely arranged, and a side wall 112 that surrounds the first end wall 114 and the second end wall 111; as long as a stable sealing and electrical connection relationship can be formed, the connection between the first end wall 114 and the side wall 112 and the connection between the second end wall 111 and the side wall 112 can be achieved in various ways, such as integral stamping, integral casting, or split welding. The surrounding of the side wall 112 is not limited, and it can be cylindrical or prismatic, or it can surround along any other closed-loop contour that can match the first end wall 114 and the second end wall 111. As an embodiment, in this embodiment, the outer edges of the first end wall 114 and the second end wall 111 are circular, the side wall 112 is cylindrically surrounded on the outer edges of the first end wall 114 and the second end wall 111, the second end wall 111 and the side wall 112 are integrally formed, and a circular opening 113 is formed at one end of the side wall 112 close to the first end wall 114. An accommodation cavity is formed inside the housing 110 surrounded by the second end wall 111 and the side wall 112 for accommodating the electrode assembly 120, the electrolyte, and other necessary battery components. Specifically, the diameter of the housing 110 can be determined according to the specific size of the electrode assembly 120, such as 18 mm, 21 mm, 46 mm, etc. The material of the housing 110 can be various, for example, copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the housing 110 from rusting during long-term use, an anti-rust material such as metallic nickel can also be plated on the surface of the housing 110.

[0053] The electrode assembly 120 is accommodated in the housing 110, and the electrode assembly 120 is a component in the secondary battery 100 where an electrochemical reaction occurs. One or more electrode assemblies 120 can be included in the housing 110. The electrode assembly 120 includes a winding structure 126 formed by laminating and winding a first electrode plate 123, a second electrode plate 121, and a separator 122. The polarities of the first electrode plate 123 and the second electrode plate 121 are opposite. In some embodiments, the first electrode plate 123 is a positive electrode plate and the second electrode plate 121 is a negative electrode plate. In other embodiments, the first electrode plate 123 is a negative electrode plate and the second electrode plate 121 is a positive electrode plate.

[0054] Please refer to Figures 1 to 2 , in this embodiment, the first electrode plate 123 is a negative electrode plate. The first electrode plate 123 includes a negative current collector 1231 and a negative active material, and the negative active material is coated on the surface of the negative current collector 1231; the negative current collector 1231 includes a first coated area 1232 coated with the active material and a first uncoated area 1233 not coated with the active material. The first uncoated area 1233 is located at the end of the first electrode plate 123. The first uncoated area 1233 extends out of the separator 122 along the winding axis direction of the electrode assembly 120 and is bent towards the winding axis to form a first tab 124, and the first tab 124 is the corresponding negative tab.

[0055] Please refer to Figures 1 to 2 , the second electrode tab 121 is a positive electrode tab. Specifically, the second electrode tab 121 includes a positive current collector 1211 and a positive active material, and the positive active material is coated on the surface of the positive current collector 1211; the positive current collector 1211 includes a second coated area 1212 coated with the active material and a second uncoated area 1213 not coated with the active material. The second uncoated area 1213 is located at the end of the second electrode tab 121. The second uncoated area 1213 extends beyond the separator 122 at the other end in the winding axis direction of the electrode assembly 120 and is bent toward the winding axis to form a second electrode ear 125, and the second electrode ear 125 is the corresponding positive electrode ear.

[0056] Please refer to Figures 1 to 2 , the separator 122 is disposed between the first electrode tab 121 and the second 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, and the positive active material 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, and the negative active material 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 outside 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.

[0057] Please refer to Figure 1 and Figure 2 , further, if the first electrode ear 124 faces the first end wall 114 or faces the second end wall 111, then the second electrode ear 125 faces the other end of the housing 110. In this embodiment, the second electrode ear 125 faces the second end wall 111 and is electrically connected to the terminal post 130 to make the terminal post 130 positively charged. The first electrode ear 124 faces the first end wall 114, and the housing 110 is electrically connected to the first electrode ear 124, thereby being negatively charged. However, in other embodiments, the first electrode ear 124 can also be connected to the terminal post 130, and the second electrode ear 125 can be connected to the housing 110.

[0058] Please refer to Figure 1 and Figure 2, the terminal post 130 passes through the second end wall 111 and is insulated from the second end wall 111. The structural form of the terminal post 130 can be any suitable form that can pass through the second end wall 111 and be electrically connected to the first pole piece 123 or the second pole piece 121. For example, the cross-section can be circular, square, prismatic, or a special-shaped contour that can achieve stable electrical conduction. One end of the terminal post 130 facing the electrode assembly 120 passes through the second end wall 111 and is directly electrically connected to the first pole ear 124 or the second pole ear 125, or is electrically connected through an indirect transfer connection. For example, the terminal post 130 can be electrically connected to the first pole piece 123 through the first current collector member 140, or can be electrically connected to the second pole piece 121 through the second current collector member 150. The end of the terminal post 130 facing away from the electrode assembly 120 is exposed to the outside of the housing 110 to form a corresponding electrode. The electrical property of the terminal post 130 can be positive or negative. For example, in one embodiment, the terminal post 130 is electrically connected to the first pole piece 123, and the first pole piece 123 is of positive polarity, then the terminal post 130 is the positive electrode, and the housing 110 forms the corresponding negative electrode. In another embodiment, the first pole piece 123 is of negative polarity, then the terminal post 130 is the negative electrode, and the housing 110 forms the corresponding positive electrode. In this embodiment, a terminal post mounting hole is provided on the second end wall 111, and the terminal post 130 is hermetically and insulatingly installed in the terminal post mounting hole. The terminal post 130 is electrically connected to the second pole ear 125 through the second current collector member 150. The end of the terminal post 130 facing away from the electrode assembly 120 is exposed to the outside of the housing 110 and is positively charged. It should be noted that the shape and structure of the second current collector member 150 are not limited, and it is suitable to be able to achieve a stable and reliable electrical connection relationship. The second current collector member 150 is connected to the positive pole ear, and it is preferably made of aluminum metal.

[0059] The terminal post 130 is made of a conductive metal material. The material of the terminal post 130 can be aluminum. If the material of the terminal post 130 is aluminum, the riveting process can be easily performed. In this embodiment, the material of the terminal post 130 is aluminum and the polarity is positive. Correspondingly, the material of the housing 110 is low-carbon steel and forms the negative electrode correspondingly. The terminal post 130 is electrically insulated from the second end wall 111 of the housing 110. The electrical insulation between the terminal post 130 and the second end wall 111 of the housing 110 can be achieved in various ways. For example, insulation can be achieved by placing an insulating washer between the terminal post 130 and the second end wall 111. Alternatively, insulation can be achieved by forming an insulating coating layer on a part of the terminal post 130. Alternatively, some of the above methods can be combined and applied.

[0060] Further, please refer to Figures 1 to 8, the electrode assembly 120 is electrically connected to the housing 110 through the first current collector member 140. Specifically, the first current collector member 140 is welded to the first tab 124. The welding method can be ultrasonic welding, resistance welding, laser welding, etc., which is not limited herein. In this embodiment, laser welding is used, and at least one set of first weld marks 141 is formed during the welding process. The number of the first weld marks 141 can be one set, two sets, three sets, four sets, five sets or more sets. It should be noted that there is a large gap between different sets of the first weld marks 141, and the welding tracks within the same set of the first weld marks 141 are close to each other; each set of the first weld marks 141 includes one or more welding points or welding lines. The shape of the first weld marks 141 can be various, for example, it can be a straight line, a curve (such as a wavy line, an arc line, a sine curve, etc.), a broken line, other irregular figures or a combination of the above, and the shape of each set of the first weld marks 141 can be the same or different, which is not limited herein, as long as the stable electrical connection between the first tab 124 and the first current collector member 140 can be achieved. The arrangement order of multiple sets of the first weld marks 141 is not limited, and it can be arranged in a horizontal and vertical order or circumferentially along the first current collector member 140, and can be adaptively designed according to the shape and size of the electrode assembly 120 and the current collector member. In addition, the first current collector member 140 is connected to the negative tab, and it is preferably made of copper metal.

[0061] Please refer to Figures 1 to 8 , the first current collector member 140 is welded to the housing 110. The first current collector member 140 can be directly welded to the side wall 112 or welded to the first end wall 114, which is not limited herein. The welding method can be ultrasonic welding, resistance welding, laser welding, etc., which is not limited herein. In this embodiment, laser welding is used, and at least one set of second weld marks 142 is formed during the welding process; the number of the second weld marks 142 can be one set, two sets, three sets, four sets, five sets or more sets. It should be noted that there is a large gap between different sets of the second weld marks 142, and the welding tracks within the same set of the second weld marks 142 are close to each other. Each set of the second weld marks 142 includes one or more welding points or welding lines. The shape of the second weld marks 142 can be various, for example, it can be a straight line, a curve (such as a wavy line, an arc line, a sine curve, etc.), a broken line, other irregular figures or a combination of the above, and the shape of each set of the second weld marks 142 can be the same or different, which is not limited herein, as long as the stable electrical connection between the housing 110 and the first current collector member 140 can be achieved. Preferably, please refer to Figures 3 to 8 , the shapes of the second weld marks 142 are all arcs centered on the center of the first current collector member 140.

[0062] It should be noted that the shape of the first current collecting member 140 can be any rotationally symmetric shape, such as a circle, a square, a regular polygon, a petal shape, or other shapes with a center of symmetry and can coincide with the original figure after rotating a certain angle around the center of symmetry. There is no limitation on this, as long as a stable and reliable electrical connection relationship can be achieved. The center of the first current collecting member 140 is its own center of symmetry. In order to improve the positioning, processing convenience, interchangeability, and unity of the first current collecting member 140 during installation, the first current collecting member 140 in this embodiment adopts a circular structure.

[0063] Specifically, in some embodiments, the first current collecting member 140 includes a current collecting body and a housing 110 connection portion connected to the outer peripheral edge of the current collecting body. The current collecting body is welded to the first tab 124, and the housing 110 connection portion is welded to the side wall 112. The specific assembly process of this structure is that the housing 110 connection portion is first welded to the side wall 112, and then a rolling groove is rolled on the side wall 112. At the same time, the housing 110 connection portion welded to the side wall 112 continues to bend towards the axis of the housing 110. Then, the first end wall 114 is placed on the side of the rolling groove away from the first current collecting member 140 and connected to the side wall 112 to seal the opening 113. The installation method of the first end wall 114 uses a mechanical seal method to seal the opening 113. In some other embodiments, please refer to Figure 1 , the first end wall 114 seals the opening 113. The outer edge shape of the first end wall 114 corresponds to the shape of the opening 113. The outer edge of the first end wall 114 is welded to the side wall 112 to seal the opening 113, and the first current collecting member 140 is welded to the first end wall 114.

[0064] Please refer to Figures 3 to 8, considering that the shortest path for current transmission from the first tab 124 to the housing 110 is along the radial direction of the current collector member to reach the housing 110. In order to achieve a shorter current transmission path between the first weld mark 141 formed by welding the first current collector member 140 and the first tab 124 and the second weld mark 142 formed by welding the first current collector member 140 and the housing 110, the following technical solution is adopted. Tangents are respectively made from the center of the first current collector member 140 to both sides along the circumferential direction of the first current collector member 140 towards the first weld mark 141 to enclose a first sector region. Tangents are respectively made from the center of the first current collector member 140 to both sides along the circumferential direction of the first current collector member 140 towards the second weld mark 142 to enclose a second sector region. Each first sector region and at least one second sector region at least partially overlap. The first weld mark 141 located in the above overlapping part can reach the second weld mark 142 along the radial direction of the current collector member, so that each first weld mark 141 has the shortest current transmission path, thereby improving the technical problem that the length of the current transmission path between the first tab 124 and the housing 110 is uncontrollable, and further achieving beneficial effects such as improving the current transmission efficiency, reducing the internal resistance, enhancing the heat dissipation performance, and improving the battery cycle life, etc., to improve the comprehensive performance of the secondary battery 100.

[0065] In an example of the secondary battery 100 of the present utility model, there are n groups of the first weld marks 141, n≥2. For example, it can be 2, 3, 4, 5, 6, 7, 8, 9 or other numbers, and there is no limitation thereto. The n groups of the first weld marks 141 are distributed along the circumferential direction of the first current collector member 140, and can be evenly distributed or unevenly distributed, and there is no limitation thereto. The central angle corresponding to the covered area of each group of the first weld marks 141 is α i (i = 1~n), and the sum of the central angles corresponding to the covered areas of the n groups of the first weld marks 141 is There are m groups of the second weld marks 142, m≥1. For example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or other numbers, and there is no limitation thereto. The m groups of the second weld marks 142 are distributed along the circumferential direction of the first current collector member 140, and can be evenly distributed or unevenly distributed. The central angle corresponding to the covered area of each group of the second weld marks 142 is β j (j = 1~m), and the sum of the central angles corresponding to the covered areas of the m groups of the second weld marks 142 is Considering that in actual assembly, the worst extreme state of the positional relationship between the first weld mark 141 and the second weld mark 142 is that along the circumferential direction of the first current collector member 140, the second weld mark 142 just falls between two adjacent first weld marks 141. At this time, there is no overlapping part between the first sector region and the second sector region. Therefore, in this technical solution, it is further limited that This setting can achieve that even when the positional relationship between the first weld mark 141 and the second weld mark 142 is in the worst extreme state, each first sector region and at least one second sector region can at least partially overlap.

[0066] Please refer to Figures 3 to 8 , in an example of the secondary battery 100 of the present utility model, the first current collector member 140 is welded to the first end wall 114 to form a second weld mark 142. In this structural form, the longer the length of the second weld mark 142, the more unfavorable it is to the strength of the structure of the first end wall 114. Especially when the second weld mark 142 forms a closed shape around the first end wall 114, a weak structure will be formed, resulting in the first end wall 114 being prone to cracking. Preferably, it is defined that This definition can make the second weld mark 142 less than one full circle along the circumferential direction of the first current collector member 140, which is beneficial to improving the structural strength of the first end wall 114.

[0067] Please refer to Figures 3 to 4 , in an example of the secondary battery 100 of the present utility model, it is further defined that and For example, it can be: 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170°, 180°, 190°, 200° or other angles that meet the requirements, etc. This definition can make the first weld mark 141 weld more first tab 124s along the circumferential direction of the first current collector member 140, which can achieve the effect of reducing the internal resistance. Also, since the current-carrying capacity per unit length of the second weld mark 142 is greater than that of the first weld mark 141, therefore, setting can achieve that while ensuring that the second weld mark 142 and the first weld mark 141 have matching current-carrying capacities, the length of the second weld mark 142 is as small as possible, which is beneficial to improving the structural strength of the first end wall 114.

[0068] Please refer to Figures 3 to 8, in an example of the secondary battery 100 of the present utility model, n groups of first welding imprints 141 are evenly distributed along the circumferential direction of the first current collector member 140. This setting is conducive to the uniform distribution of current between the first current collector member 140 and the first tab 124, so as to reduce the overheating problem caused by too high local current density. At the same time, it helps to maintain the consistency of the secondary battery 100 to improve production efficiency. The central angles formed by connecting the centers of the first current collector member 140 with the points closest to the center of the first current collector member 140 where each adjacent two groups of first welding imprints 141 are located are γ. Preferably, γ ≤ 120°, for example, it can be 10°, 20°, 30°, 40°, 45°, 60°, 70°, 80°, 90°, 100°, 110° or 120°, etc. This setting can ensure that there are at least 3 groups of first welding imprints 141 along the circumferential direction of the first current collector member 140. The more the first welding imprints 141 are, the larger the circumferential span of the first sector area formed by the first welding imprints 141 is, and the easier it is to generate an overlapping part with the second sector area formed by the second welding imprints 142. Correspondingly, the length requirement for the second welding imprints 142 is lower, which is beneficial to enhancing the strength of the first end wall 114. In addition, the more the first welding imprints 141 are, the more first tabs 124 are connected, which is beneficial to reducing the internal resistance of the battery, improving the current overcurrent capacity, reducing heat generation, and improving the comprehensive performance of the secondary battery 100.

[0069] Please refer to Figures 3 to 8 , in an example of the secondary battery 100 of the present utility model, along the circumferential direction of the first current collector member 140, tangents are respectively made from the center of the first current collector member 140 to the outermost points on the adjacent sides of each adjacent two groups of first welding imprints 141, and the formed central angle is δ. Preferably, δ ≤ 90°, for example, it can be 10°, 20°, 30°, 40°, 45°, 60°, 70°, 80° or 90°, etc. This setting can ensure that the first welding imprints 141 have a large span along the circumferential direction of the first current collector member 140. The larger the circumferential span of the first sector area formed by the first welding imprints 141 is, the easier it is to generate an overlapping part with the second sector area formed by the second welding imprints 142. Correspondingly, the length requirement for the second welding imprints 142 is lower, which is beneficial to enhancing the strength of the first end wall 114. In addition, this setting can also increase the number of first tabs 124 welded to the first welding imprints 141, which is beneficial to reducing the internal resistance of the battery, improving the current overcurrent capacity, reducing heat generation, and further improving the comprehensive performance of the secondary battery 100.

[0070] Please refer to Figures 3 to 8, in an example of the secondary battery 100 of the present utility model, along the radial direction of the first current collector member 140, the maximum distance from the first welding mark 141 to the center of the first current collector member 140 is R1, and the maximum distance from the second welding mark 142 to the center of the first current collector member 140 is R2. Preferably, the difference between R2 and R1 is defined as R2 - R1 ≤ 10 mm. For example, it can be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, etc. Defining R2 - R1 ≤ 10 mm means defining the maximum distance between the first welding mark 141 and the second welding mark 142 to be less than 10 mm. This setting enables a smaller distance between the first welding mark 141 and the second welding mark 142, which can reduce the resistance between the first welding mark 141 and the second welding mark 142, improve the overcurrent capacity of the current, reduce heat generation, so as to improve the comprehensive performance of the secondary battery 100. In addition, this limitation can keep a safe distance between the second welding mark 142 and the tab cutting area at the outer edge of the first tab 124, prevent the separator 122 from being scalded during the welding of the second welding mark 142, and reduce the risk of causing a short circuit inside the secondary battery 100.

[0071] Please refer to Figures 3 to 8 , in an example of the secondary battery 100 of the present utility model, along the radial direction of the first current collector member 140, the minimum distance from the first welding mark 141 to the center of the first current collector member 140 is R3, and the radius of the outer peripheral edge of the first current collector member 140 is R4. Preferably, the relationship between the difference between R1 and R3 and R4 is defined as 0.2R4 ≤ R3 < R1 ≤ 0.9R4. For example, it can be 0.2R4, 0.3R4, 0.4R4, 0.5R4, 0.6R4, 0.7R4, 0.8R4 or 0.9R4, etc. The area of the first tab 124 corresponding to the region of 0.2R4 to 0.9R4 is the region where the number of tab layers is relatively stable. The number of layers of the first tab 124 in this region is the largest and relatively uniform. Distributing the first welding mark 141 in the stable region of the stacked layers of the first tab 124 can achieve connection with a larger number of layers of the first tab 124 and is not easily welded through, so as to achieve the effects of reducing the internal resistance, improving the conductivity, safety and energy density, etc., and improving the battery performance.

[0072] Please refer to Figures 3 to 8, in an example of the secondary battery 100 of the present utility model, along the radial direction of the first current collector member 140, the radius of the winding structure 126 is R5. Preferably, the difference between R5 and R1 is defined as R5 - R1 ≤ 10 mm. For example, it can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, etc. The setting of R5 - R1 ≤ 10 mm can be understood as the distance from the position where the first welding mark 141 is farthest from the center of the first current collector member 140 to the outer peripheral edge of the winding structure 126 is less than or equal to 10 mm. This setting makes the first welding mark 141 have a relatively close distance to the outer peripheral edge of the winding structure 126. On the one hand, it can achieve the effect of increasing the number of turns connected to the first tab 124. On the other hand, since the single-turn length of the winding structure 126 is larger closer to the outer peripheral edge, the effect of reducing the internal resistance and improving the battery performance when the first welding mark 141 increases the number of connection turns at the position close to the outer peripheral edge is more prominent.

[0073] Please refer to Figures 3 to 8 , in an example of the secondary battery 100 of the present utility model, along the radial direction of the first current collector member 140, the winding structure 126 includes a winding hole 127, and the radius of the winding hole 127 is R6. Preferably, the difference between R6 and R3 is defined as R3 - R6 ≤ 10 mm. For example, it can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, etc. The setting of R3 - R6 ≤ 10 mm can be understood as the distance from the position where the first welding mark 141 is closest to the center of the first current collector member 140 to the inner peripheral edge of the winding structure 126 is less than or equal to 10 mm. This setting makes the first welding mark 141 have a relatively close distance to the inner peripheral edge of the winding structure 126, and can achieve the effect of increasing the number of turns connected to the first tab 124, thereby achieving the effects of reducing the internal resistance, improving the conductivity, safety and energy density, etc., and improving the battery performance.

[0074] Please refer to Figures 3 to 8, in an example of the secondary battery 100 of the present utility model, along the radial direction of the first current collector member 140, the maximum length of the first welding mark 141 is L. Preferably, L is limited to 0.3×(R5 - R6) ≤ L ≤ 0.8×(R5 - R6). For example, it can be 0.3×(R5 - R6), 0.4×(R5 - R6), 0.5×(R5 - R6), 0.6×(R5 - R6), 0.7×(R5 - R6), or 0.8×(R5 - R6), etc. The length of the first welding mark 141 is limited to the region of 0.3×(R5 - R6) ≤ L ≤ 0.8×(R5 - R6). R5 - R6 represents the radial width value of the winding structure 126. The limitation of L≥0.3×(R5 - R6) can enable the first welding mark 141 to connect more turns of the first tab 124. The limitation of L≤0.8×(R5 - R6) makes the length of the first welding mark 141 basically correspond to the width of the region where the number of layers of the first tab 124 is the largest and relatively uniform. If the first welding mark 141 is distributed in the stable stacking layer region, it can connect more layers with the first tab 124 and is not easily welded through, so as to reduce the internal resistance, improve the conductivity, safety, and energy density, etc., and improve the battery performance.

[0075] Considering that the outermost first tab 124 is in a free state and has a risk of breaking off, in an example of the secondary battery 100 of the present utility model, along the axial direction of the first current collector member 140, the first current collector member 140 at least covers part of the outermost first tab 124 of the winding structure 126. Enabling at least part of the outermost first tab 124 to be covered and pressed by the first current collector member 140 can effectively prevent the first tab 124 from warping, so as to reduce the risk of the first tab 124 breaking under external force and falling into the interior of the housing 110, causing a short circuit.

[0076] In an example of the secondary battery 100 of the present utility model, please refer to Figure 3 and Figure 4 , the n value of the first welding mark 141 is 4. The shape of each group of the first welding marks 141 is the same, and it is a Y-shaped structure formed by three straight lines opening towards the outer periphery of the first current collector member 140, and is evenly arranged along the circumferential direction of the first current collector member 140. α1 = α2 = α3 = α4 = 50°, the m value of the second welding mark 142 is 3. The shapes of the second welding marks 142 are all arcs with the center of the first current collector member 140 as the center of the circle, and are evenly arranged along the circumferential direction of the first current collector member 140. β1 = β2 = β3 = β4 = 48.5°, and γ = 90° < 120°, δ = 40° < 90°. R1 = 15mm, R2 = 20.5mm, R3 = 4.7mm, R4 = 23mm, R5 = 21mm, R6 = 2.6mm, L = 10.3mm.

[0077] In another example of the secondary battery 100 of the present utility model, please refer to Figure 5 and Figure 6 , there are 4 groups of the first welding marks 141, and the shapes of each group of the first welding marks 141 are the same, each composed of three wavy lines arranged in parallel, and are evenly arranged circumferentially along the first current collector member 140. α1 = α2 = α3 = α4 = 32.5°, The m value of the second welding mark 142 is 3, and the shapes of the second welding marks 142 are all arcs centered on the center of the first current collector member 140, and are evenly arranged circumferentially along the first current collector member 140, β1 = β2 = β3 = 87°, γ = 90° < 120°, δ = 57.5° < 90°. R1 = 16mm, R2 = 21.5mm, R3 = 6.5mm, R4 = 23mm, R5 = 21mm, R6 = 2.6mm, L = 9.5mm.

[0078] In yet another example of the secondary battery 100 of the present utility model, please refer to Figure 7 and Figure 8 , there are 3 groups of the first welding marks 141, and the shapes of each group of the first welding marks 141 are the same, each being a V-shaped structure opening towards the outer peripheral edge of the first current collector member 140, and are evenly arranged circumferentially along the first current collector member 140. α1 = α2 = α3 = 60°, The m value of the second welding mark 142 is 3, and the shapes of the second welding marks 142 are all arcs centered on the center of the first current collector member 140, and are evenly arranged circumferentially along the first current collector member 140, β1 = β2 = β3 = 90°, γ = 120°, δ = 60° < 90°. R1 = 15mm, R2 = 21mm, R3 = 7.5mm, R4 = 23mm, R5 = 21mm, R6 = 2.6mm, L = 10mm.

[0079] Please refer to Figure 9 , the present utility model further 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 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 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 utility model, the battery pack 10 may also include parts such as a battery pack thermal management system and a circuit board. The battery pack 10 may be a battery module or a battery pack, an energy storage electric cabinet, etc.; details are not elaborated herein one by one.

[0080] Please refer to Figure 10 , the present utility model further provides an electronic device 1, and the electronic device 1 includes the above battery pack 10. The working part 11 is electrically connected to the battery pack 10 to obtain electrical energy 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 thereto. The working part 11 is the vehicle body, and the battery pack 10 is arranged at the bottom of the vehicle body and provides electrical energy support for the running of the vehicle or the operation of the electrical components in the vehicle. However, in some other embodiments, the electronic device 1 can also be a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy and an electric tool, etc. The spacecraft includes an airplane, a rocket, a space shuttle and a spaceship, etc.; the working part 11 can be a unit component that can obtain the electrical energy of the battery pack 10 and perform corresponding work, such as the fan blade rotation unit of a fan, the dust suction working unit of a vacuum cleaner, etc. The electric toy includes a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy and an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and a railway electric tool, for example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator and a planer, etc. The embodiments of the present application do not impose special restrictions on the above electronic device 1.

[0081] For the secondary battery of the present utility model, along the circumferential direction of the first current collector member, the first fan-shaped region is formed by connecting the center lines of the outermost ends on both sides of each group of first welding marks to the center of the first current collector member, and the second fan-shaped region is formed by connecting the center lines of the outermost ends on both sides of each group of second welding marks to the center of the first current collector member. Each first fan-shaped region and at least one second fan-shaped region at least partially overlap. The first welding mark located in the overlapping part can reach the second welding mark along the radial direction of the current collector member, having the shortest current transmission path, so as to improve the technical problem that the length of the current transmission path between the first tab and the housing is uncontrollable, and further achieve the beneficial effects of improving the current transmission efficiency, reducing the internal resistance, enhancing the heat dissipation performance, improving the battery cycle life, etc., and improving the comprehensive performance of the secondary battery. Therefore, the present utility model effectively overcomes some practical problems in the prior art and thus has high utilization value and practical significance. The above embodiments are only illustrative of the principles and effects of the present utility model and are not used to limit the present utility model. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present utility model. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present utility model should still be covered by the claims of the present utility model.

Claims

1. A secondary battery, characterized in that, Comprising: A housing including a first end wall and a second end wall disposed opposite to each other, and a side wall surrounding the first end wall and the second end wall; An electrode assembly accommodated in the housing, the electrode assembly including a winding structure formed by laminating and winding a first electrode tab, a second electrode tab, and a separator, and an end of the first electrode tab including a first electrode ear extending out of the separator and bent along the winding axis direction of the electrode assembly; A first current collector member welded to the first electrode ear and formed with at least one set of first welding marks, the first current collector member welded to the housing and formed with at least one set of second welding marks; Wherein, tangents are respectively made from the center of the first current collector member to both sides of the first welding marks along the circumferential direction of the first current collector member to enclose a first sector region, and tangents are respectively made from the center of the first current collector member to both sides of the second welding marks along the circumferential direction of the first current collector member to enclose a second sector region, and each of the first sector regions and at least one of the second sector regions at least partially overlap.

2. The secondary battery according to claim 1, wherein The first solder joints are in n groups, where n≥2, and the n groups of the first solder joints are circumferentially distributed along the first current collector member. The central angle corresponding to the covered area of each group of the first solder joints is α i (i = 1 to n), and the sum of the central angles corresponding to the covered areas of the n groups of the first solder joints is The second solder joints are in m groups, where m≥1, and the m groups of the second solder joints are circumferentially distributed along the first current collector member. The central angle corresponding to the covered area of each group of the second solder joints is β j (j = 1 to m), and the sum of the central angles corresponding to the covered areas of the m groups of the second solder joints is Among them, 3. The secondary battery according to claim 2, wherein The first current collector member is welded to the first end wall to form the second weld mark, wherein, 4. The secondary battery according to claim 3, wherein and 5. The secondary battery according to claim 2, wherein n sets of the first welding marks are evenly distributed along the circumferential direction of the first current collector member, and the central angles formed by connecting the center of the first current collector member to the points closest to the center of the first current collector member for each adjacent two sets of the first welding marks are γ, where γ ≤ 120°.

6. The secondary battery according to claim 5, characterized in that, The central angle formed by respectively making tangents from the center of the first current collector member to the outermost points on the adjacent sides of each adjacent two sets of the first welding marks is δ, where δ ≤ 90°.

7. The secondary battery according to claim 1, wherein Along the radial direction of the first current collector member, the maximum distance from the first welding mark to the center of the first current collector member is R1, and the maximum distance from the second welding mark to the center of the first current collector member is R2, where R2 - R1 ≤ 10 mm.

8. The secondary battery according to claim 7, wherein Along the radial direction of the first current collector member, the minimum distance from the first welding mark to the center of the first current collector member is R3, and the radius of the outer peripheral edge of the first current collector member is R4, where 0.2R4 ≤ R3 < R1 ≤ 0.9R4.

9. The secondary battery according to claim 8, wherein The winding structure includes a winding hole, and along the radial direction of the first current collector member, the radius of the winding hole is R6, where R3 - R6 ≤ 10 mm.

10. The secondary battery according to claim 7, wherein Along the radial direction of the first current collector member, the radius of the winding structure is R5, where R5 - R1 ≤ 10 mm.

11. The secondary battery according to claim 1, characterized in that, Along the axial direction of the first current collector member, the first current collector member at least covers a part of the first electrode ear located on the outermost side of the winding structure.

12. A battery pack, characterized in that, Including the secondary battery according to any one of claims 1 to 11.

13. An electronic device, characterized in that, Including the battery pack according to claim 12.

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