Convergence plate and battery

Abstract

The utility model provides a confluence plate and a battery, relates to the technical field of battery production and processing, and aims to solve the problems of over-welding and the like caused by welding energy concentration due to inflection points and overlapping points in a welding track on the premise of ensuring the welding strength and the overflowing area in the welding process between the battery confluence plate and a roll core. Comprising a confluence disc, a plurality of welding tracks are formed on one side of the confluence disc to be combined with a roll core, the welding tracks are distributed around the confluence disc in an annular array mode, and the welding tracks are in a smooth wavy curve shape.

Description

Technical Field

[0001] The present application relates to the technical field of battery production and processing, and in particular to a busbar and a battery. Background Art

[0002] Cylindrical batteries are generally welded together by laser welding the battery busbar and the winding core to ensure the strength of the connection and the flow area on the pole and the connecting piece. In the related art, the laser welding trajectory between the battery busbar and the winding core can adopt a zigzag welding trajectory. The zigzag welding trajectory requires the speed of the laser beam to be reduced to zero near the inflection point and then increased from zero to accelerate. Therefore, the laser energy will accumulate at the inflection point, resulting in a large welding depth and the risk of welding through. Alternatively, the laser welding trajectory between the battery busbar and the winding core can also adopt a spiral curve trajectory (see Figure 1 As shown in FIG. 1 , the curved track has multiple overlapping welding points, which easily cause over-welding at the overlapping welding points, thereby causing structural welding penetration. The above-mentioned problems lead to poor battery welding quality in the related art. Utility Model Content

[0003] In view of this, the present application provides a busbar and a battery, which are used to improve the welding energy concentration caused by the presence of inflection points and overlapping points in the welding trajectory during the welding process between the battery busbar and the winding core, while ensuring the welding strength and the flow area, thereby causing problems such as over-welding.

[0004] The technical solution adopted by this application to solve the above technical problems is:

[0005] In a first aspect, the present application provides a busbar, including a busbar having a welding side and a back side that are relatively arranged, the welding side is used for welding to a winding core, and the back side is provided with a welding track, and the welding track presents a smooth wavy curve.

[0006] In some embodiments of the present application, the welding track includes a plurality of semicircular portions and a plurality of straight portions, and the plurality of semicircular portions and the plurality of straight portions are alternately arranged and connected in sequence.

[0007] In some embodiments of the present application, a plurality of the straight line portions are sequentially arranged in parallel and at intervals.

[0008] In some embodiments of the present application, the welding track extends along the radial direction of the busbar.

[0009] In some embodiments of the present application, there are multiple welding tracks, and each of the welding tracks is arranged in sequence around the center of the busbar.

[0010] In some embodiments of the present application, the busbar is a positive busbar, and the positive busbar includes a busbar body and lead-out tabs extending from the busbar body.

[0011] In some embodiments of the present application, the welding trajectory presents a circular closed wave curve arranged around the center of the busbar.

[0012] In some embodiments of the present application, the thickness of the positive busbar is 0.1 to 0.5 mm.

[0013] In a second aspect, the present application provides a battery, comprising a winding core and a busbar as described in any one of the above items, wherein the welding side of the busbar is welded to the pole lug of the winding core, and the welding track on the busbar overlaps with the pole lug at the orthographic projection of the welding side.

[0014] In some embodiments of the present application, the winding core includes a core portion and an outer peripheral surface formed by winding the first electrode, the second electrode and the separation membrane sandwiched therebetween around a winding axis as the center;

[0015] The first electrode includes an active material coated portion and an uncoated portion along the winding direction, at least a portion of the uncoated portion serves as an electrode tab, the uncoated portion includes a first portion adjacent to the core of the winding core, a second portion adjacent to the outer peripheral surface of the winding core, and a third portion between the first portion and the second portion, and along the winding axis direction, the height of the first portion and / or the second portion is lower than the height of the third portion;

[0016] The third portion and the second portion are divided into a plurality of segments that can be bent individually, and the plurality of segments form a bending surface area when bent along the radial direction of the winding core; the bending surface area is the pole ear of the winding core;

[0017] Along the direction approaching from the core side to the peripheral side, the bending surface area includes a uniform stacking number interval and a stacking number reduced interval, the stacking number of the slices in the uniform stacking number interval is uniform, the stacking number of the slices in the stacking number reduced interval is located outside the uniform stacking number interval, and the stacking number of the slices in the stacking number reduced interval decreases as approaching the peripheral side.

[0018] In some embodiments of the present application, the stacking number of the slices in the uniform stacking number interval is more than 10 layers.

[0019] In some embodiments of the present application, the projection area of ​​the welding track on the bending surface area is completely located within the uniform interval of the stacking number.

[0020] In some embodiments of the present application, the width of the welding track is greater than the width of the tab.

[0021] In some embodiments of the present application, along the radial direction of the winding core, the welding track is at least partially welded to two adjacent sections in the same circle.

[0022] In summary, due to the adoption of the above technical solution, this application has at least the following beneficial effects:

[0023] A busbar and a battery provided by the present application, in an embodiment of the present application, by setting the welding trajectory as a smooth wavy curve without cross-overlapping, it is possible to make it difficult for the welding trajectory to have an inflection point, so that the welding energy at the inflection point will not be too large, thereby preventing the busbar from being punctured, and there will be no situation in the related art where spiral welding is used to cause multiple overlapping points on the busbar, thereby causing the welding energy at the overlapping points on the busbar to be too large. Multiple welding trajectories are then evenly arranged in an array on the busbar, which can make the connection between the busbar and the winding core more secure and the flow area larger, while preventing over-welding, thereby improving the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments are briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present application, but are not intended to limit the present application, wherein:

[0025] Figure 1 It is a structural schematic diagram of a busbar in the related art;

[0026] Figure 2 A schematic diagram of the structure of a negative busbar provided in an embodiment of the present application;

[0027] Figure 3 A schematic diagram of the structure of a positive busbar provided in an embodiment of the present application;

[0028] Figure 4 Another schematic diagram of the structure of the negative busbar provided in the embodiment of the present application;

[0029] Figure 5 Another structural schematic diagram of the positive busbar provided in the embodiment of the present application;

[0030] Figure 6 A third structural schematic diagram of the negative busbar provided in the embodiment of the present application;

[0031] Figure 7 A cross-sectional structural diagram of a battery provided in an embodiment of the present application;

[0032] Figure 8 This is a schematic diagram of the structure of the electrode tab provided in an embodiment of the present application.

[0033] The accompanying drawings are as follows:

[0034] 11. Busbar body; 12. Lead-out tab; 2. Welding track; 21. Semicircular portion; 22. Straight portion; 3. Winding core; 31. Cut piece; A. First portion; B. Second portion; C. Third portion. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0036] In the description of this application, it should be understood that the words "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0037] In this application, the word "exemplary" is used to mean "used as an example, illustration, or description". Any embodiment described in this application as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The following description is given to enable any technician in the field to implement and use the present application. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the present application can be implemented without using these specific details. In other instances, known structures and processes are not elaborated in detail to avoid obscuring the description of the present application with unnecessary details. Therefore, the present application is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles disclosed in this application.

[0038] In the related art, the battery busbar includes a positive busbar and a negative busbar. The positive busbar needs to be welded to the winding core, and the negative battery needs to be welded to the winding core. Thus, multiple cells can be converged to form a battery pack for supplying energy to the powered equipment. The welding between the battery busbar and the winding core is more uniform, and the welding strength and current capacity of multiple welding points between the battery busbar and the winding core are better, and the welding effect is better.

[0039] The welding track used in the connection structure between the battery busbar and the winding core in the related art is usually in the shape of a broken line and a spiral, so it is easy to have inflection points and overlapping points, resulting in over-welding between the battery busbar and the winding core.

[0040] Based on the above busbar, see Figure 2 and Figure 3 As shown, Figure 2 A schematic diagram of the structure of the negative busbar provided in the embodiment of the present application is shown in FIG. Figure 3 A structural schematic diagram of a positive busbar provided in an embodiment of the present application, the present application provides a busbar having a welding side and a back side relatively arranged, the welding side is used for welding with a winding core 3, the back side is provided with a welding track 2, and the welding track 2 presents a smooth wavy curve.

[0041] It is understandable that the smooth wavy curve can be any curve without inflection points and overlap points (no intersection), for example, it can be a sine curve, or a curve without inflection points composed of straight lines and curves, or even a random curve.

[0042] In the related art, some welding trajectories are bent straight lines with multiple inflection points. Therefore, during the welding process, the laser beam needs to accelerate on the straight line and then maintain a uniform speed. It needs to decelerate when it is about to reach the inflection point until the speed of the laser beam drops to 0 at the inflection point, and then the speed of the laser beam increases from 0. Therefore, the energy of the laser beam accumulates greatly at the inflection point, which can easily cause a large welding depth and the risk of welding through. The welding trajectory is set to a spiral pattern. Although there are no inflection points in the welding trajectory, there are multiple overlapping points. The existence of overlapping points in the welding trajectory means that the welding energy at that location is too high, and over-welding is likely to occur at that location. Both situations have over-welding to varying degrees, thus affecting the welding effect.

[0043] The beneficial effects of the present application are as follows: by setting the welding track 2 as a smooth wavy curve without cross-overlap (the wavy curve can be a smooth curve or a non-smooth curve, and the non-smooth wavy curve may also have inflection points), it is possible to make it difficult for the welding track 2 to have inflection points, so that the welding energy at the inflection point will not be too large, thereby preventing the busbar from being punctured, and there will be no situation in the related art where spiral welding results in multiple overlapping points on the busbar, thereby causing the welding energy at the overlapping points on the busbar to be too large. Multiple welding tracks 2 are then evenly arranged in an array on the busbar, which can make the connection between the busbar and the winding core 3 more secure and the flow area larger, while preventing over-welding, thereby improving the welding quality.

[0044] The busbar in this embodiment is suitable for steel shell cylindrical battery cells, and can certainly be used for batteries of other shapes (such as square).

[0045] In some examples of this application, see Figure 4 and Figure 5 As shown, Figure 4 Another schematic diagram of the structure of the negative busbar provided in the embodiment of the present application is shown in FIG. Figure 5This is another structural schematic diagram of the positive busbar provided in an embodiment of the present application, wherein the welding track 2 includes a plurality of semicircular portions 21 and a plurality of straight portions 22, and the plurality of semicircular portions 21 and the plurality of straight portions 22 are alternately arranged and connected in sequence.

[0046] The alternating arrangement means that the straight portion 22 and the semicircular portion 21 are connected end to end, one end of a straight portion 22 is connected to one end of a semicircular portion 21 , and the other end of the straight portion 22 is connected to one end of another semicircular portion 21 .

[0047] It should be understood that the semicircular portion 21 is not limited to a semicircular curve, but can also be a part of an elliptical curve. The straight portion 22 can be a straight line or a curve with a certain curvature. The semicircular portion 21 and the straight portion 22 need to be tangent to each other so that the overall welding trajectory is a smooth (without inflection point) curve. This curve is broadly regarded as a wavy curve, but the wavy curve is not limited to the curve composed of the straight portion 22 and the semicircular portion 21.

[0048] It can be understood that the multiple semicircular portions 21 and the multiple straight portions 22 are alternately arranged in sequence and connected to form a wavy curve trajectory, which has no overlapping points and inflection points and is an optimized structure of the above-mentioned ordinary wavy arc.

[0049] The embodiment of the present application converts the wavy curve into a semicircular portion 21 and a straight portion 22, and alternately arranges and connects the semicircular portion 21 and the straight portion 22, so that the width of the welding track 2 (i.e., the length direction of the straight portion 22 in the wavy curve, and further, the circumferential length of the busbar) is wider, so that the welding track 2 can be on a larger surface area of ​​the busbar, so that the welding contact surface is larger and more uniform, thereby making the connection strength between the busbar and the winding core 3 higher, and at the same time making the flow area between the busbar and the winding core 3 larger, thereby increasing the overall effective flow area of ​​the battery, so there is no need to consider the problem of additional filling welding in the blank space.

[0050] In some examples of this application, see Figure 4 and Figure 5 As shown, a plurality of straight line portions 22 are sequentially arranged in parallel and at intervals.

[0051] It can be understood that the fact that the plurality of straight portions 22 are arranged in parallel and spaced apart in sequence does not necessarily mean that the length of each straight portion 22 is the same, and the lengths of the plurality of straight portions 22 in each welding track 2 may be different.

[0052] Furthermore, the straight portion 22 may also be a portion of a circle surrounding the center of the busbar (i.e., an arc at one end). As long as multiple arcs (i.e., the straight portions 22) are parallel to each other, the diameter of each semicircular portion 21 in the welding track can also be kept consistent.

[0053] By arranging the straight portions 22 parallel to each other, the diameter of the semicircular portion 21 in the welding track 2 on the surface of the busbar can be maximized, so that during the welding process, the laser beam can more easily turn without deceleration or turn smoothly with the minimum deceleration, so that the variance of the welding energy value at each location of the welding track 2 is minimized, and the distribution of the welding energy at various locations of the welding track 2 is more uniform, thereby effectively preventing over-welding at the bend of the welding track 2.

[0054] In some embodiments of the present application, the welding track 2 extends along the radial direction of the busbar.

[0055] It can be understood that the welding track 2 can be extended radially along the busbar and connected along the diameter direction of the busbar, or it can be offset at a certain angle relative to the diameter direction of the busbar, so that one end of the welding track 2 is toward the center of the busbar, and the other end of the welding track 2 is toward the edge of the busbar.

[0056] By extending multiple welding tracks 2 along the radial direction of the busbar, the number of connection layers between the busbar and the pole ears on the winding core 3 can be increased, so that the connection strength between the busbar and the winding core 3 after welding and the flow area between the busbar and the winding core 3 are larger, thereby making the overall flow effect of the battery better.

[0057] In some embodiments of the present application, there are multiple welding tracks 2, and each of the welding tracks 2 is arranged in sequence around the center of the busbar.

[0058] The number of welding tracks 2 distributed in the annular array around the busbar can be set to eight as long as it can meet the welding strength and flow area between the busbar and the winding core 3. More than eight will reduce the welding efficiency, and less than eight will easily lead to reduced welding strength. The reason for setting a plurality of welding tracks 2 is to reduce the welding time between the busbar and the winding core 3 in the battery.

[0059] It should be understood that the annular array distribution of the welding tracks 2 around the busbar requires that the distance between adjacent welding tracks 2 remain consistent to ensure that the busbar and the winding core 3 have a higher overall welding strength and a larger overall flow area.

[0060] By distributing the welding tracks 2 in an annular array around the busbar, the welding time between the busbar and the winding core 3 can be greatly reduced while ensuring sufficiently strong welding strength and a sufficiently large flow area between the winding core and the busbar, thereby improving the efficiency of the entire welding process and thus improving the efficiency of the entire battery preparation process.

[0061] In some embodiments of the present application, the busbar can be a positive busbar or a negative busbar, which is not limited in the present application. In some embodiments, the busbar can be a positive busbar, which includes a circular busbar body 11 and a lead-out tab 12 extending from the busbar body 11.

[0062] It should be noted that the shapes of the positive busbar and the negative busbar may be different. The positive busbar includes a body 11 and a tab 12. However, the welding tracks on the positive busbar and the negative busbar need to meet the requirements of no inflection points and overlap points.

[0063] In some examples of this application, see Figure 6 As shown, Figure 6 This is a third structural schematic diagram of the negative electrode busbar provided in an embodiment of the present application, wherein the welding track 2 presents a circular closed wave curve arranged around the center of the busbar.

[0064] The welding track 2 can also be a closed annular welding track 2 around the center of the busbar, which can also prevent the welding track 2 from generating inflection points and overlapping points, so that the welding energy of the inflection points and overlapping points generated on the welding track 2 is too high, thereby causing over-welding, thereby avoiding damaging the welding strength between the winding core 3 and the busbar and reducing the flow area between the winding core 3 and the busbar. It should be noted that this is limited to an example of another embodiment in which the curve has no inflection points and no overlapping points.

[0065] In some embodiments, the busbar is a copper sheet. The busbar may also be made of a copper sheet with a coating, wherein the coating may be a chemical coating.

[0066] Some embodiments of the present application can relatively reduce the internal resistance of the busbar by setting the material of the busbar to copper sheet, which can reduce the heat generation during the operation of the busbar, thereby reducing the overcurrent loss of the busbar and the winding core and improving the overall conductivity of the battery.

[0067] The thickness of the busbar can be determined according to actual needs, and the embodiments of the present application do not limit this. In some embodiments of the present application, the thickness of the busbar is 0.1-0.5 mm, and further, it can be 0.15-0.25 mm, for example, 0.15 mm, 0.20 mm, 0.25 mm, etc.

[0068] Some embodiments of the present application can ensure that the busbar or the winding core 3 will not be welded through during the welding process by setting the thickness of the busbar to 0.1-0.5 mm.

[0069] In some embodiments of the present application, the welding track 2 is a laser welding track, so that the laser beam can perform laser welding on the busbar and the winding core 3 along the welding track 2 .

[0070] The embodiment of the present application can improve the welding quality by using laser welding for the welding track.

[0071] In a second aspect, the present application provides a battery, see Figure 7 As shown, Figure 7 The cross-sectional structure diagram of the battery provided in the embodiment of the present application, the battery includes a core 3 and a busbar of any of the above-mentioned items, the welding side of the busbar is welded to the pole ear of the core 3, and the welding track 2 on the busbar overlaps with the pole ear at the welding side. Since the battery is provided with the busbar of the above-mentioned embodiment, it has all the beneficial effects of the busbar in any of the above-mentioned embodiments, that is, the welding track between the busbar and the core 3 in the battery has no overlapping points and no inflection points, so that the welding energy at the inflection point will not be too large to pierce the busbar, and there will be no spiral welding in the related technology, which will result in multiple overlapping points on the busbar, thereby causing excessive welding energy at the overlapping points on the busbar. Multiple welding tracks 2 are evenly arranged in an array on the busbar, which can make the connection between the busbar and the core 3 more secure without over-welding, thereby improving the welding quality.

[0072] In some embodiments, see Figure 8 As shown, Figure 8 The structure diagram of the electrode ear provided in the embodiment of the present application is shown in FIG. 3 . The winding core 3 includes a core portion and an outer peripheral surface formed by winding the first electrode, the second electrode and the separation membrane sandwiched therebetween around a winding axis as the center.

[0073] The first electrode includes an active material coated portion and an uncoated portion along the winding direction, at least a portion of the uncoated portion serves as an electrode tab, the uncoated portion includes a first portion A adjacent to the core of the winding core 3, a second portion B adjacent to the outer peripheral surface of the winding core 3, and a third portion C between the first portion A and the second portion B, and along the winding axis direction, the height of the first portion A and / or the second portion B is lower than the height of the third portion C;

[0074] The third portion C is divided into a plurality of segments 31 that can be bent individually. The plurality of segments 31 form a bending surface area when bent along the radial direction of the winding core 3. The bending surface area is the pole ear of the winding core 3. It can be understood that the first portion A and the second portion B may also be divided.

[0075] Along the direction from the core side to the peripheral side, the bending surface area includes a uniform stacking number interval and a stacking number reduced interval. The stacking number of the slice 31 in the uniform stacking number interval is uniform, and the stacking number of the slice 31 in the stacking number reduced interval is located outside the uniform stacking number interval. The stacking number of the slice 31 in the stacking number reduced interval decreases as approaching the peripheral side.

[0076] It can be understood that the second electrode also includes an active material coated portion and an uncoated portion along the winding direction, at least a portion of the uncoated portion serves as an electrode tab, and the uncoated portion includes a first portion A adjacent to the core of the winding core 3, a second portion B adjacent to the outer peripheral surface of the winding core 3, and a third portion C between the first portion A and the second portion B. Along the winding axis direction, the height of the first portion A and / or the second portion B is lower than the height of the third portion C;

[0077] The third portion C is divided into a plurality of segments 31 that can be bent individually. The plurality of segments 31 form a bending surface area when bent along the radial direction of the winding core 3. The bending surface area is the pole ear of the winding core 3. It can be understood that the first portion A and the second portion B may also be divided.

[0078] Along the direction from the core side to the peripheral side, the bending surface area includes a uniform stacking number interval and a stacking number reduced interval. The stacking number of the slice 31 in the uniform stacking number interval is uniform, and the stacking number of the slice 31 in the stacking number reduced interval is located outside the uniform stacking number interval. The stacking number of the slice 31 in the stacking number reduced interval decreases as approaching the peripheral side.

[0079] In some embodiments, the stacking number of the slices 31 in the uniform stacking number range is more than 10.

[0080] It can be understood that the region where the stacking number of the sections 31 reaches 10 or more can be set as a preferred welding target region.

[0081] In some embodiments, the projection area of ​​the welding track 2 on the bending surface area is completely located within the uniform interval of the stacking number.

[0082] It can be understood that the uniform stacking number interval is the area with the largest number of stacking numbers on the bending surface area, so that when the collector plate is welded to the pole ear of the winding core 3, the pole ear of the winding core 3 will not be welded through.

[0083] In some embodiments, the width of the welding track 2 is greater than the width of the segment 31 .

[0084] In this way, it can be ensured that the welding track 2 can be successfully welded to two adjacent tabs in the same circle layer.

[0085] In some embodiments, along the radial direction of the winding core, the welding track 2 is at least partially welded to two adjacent sections 31 in the same turn.

[0086] In this way, it can be ensured that the welding track 2 can be successfully welded to two adjacent tabs in the same circle layer.

[0087] See also Figure 7 As shown, the welding side of the busbar is welded to the pole ear of the winding core 3, wherein the positive pole ear of the winding core 3 is made of aluminum foil, and the negative pole ear is made of copper foil.

[0088] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0089] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0090] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more application embodiments, in the above description of the embodiments of this application, multiple features are sometimes merged into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0091] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this application is hereby incorporated by reference in its entirety, except for application history documents that are inconsistent with or conflicting with the content of this application, and documents that limit the broadest scope of the claims of this application (currently or later attached to this application). It should be noted that if the descriptions, definitions, and / or use of terms in the attached materials of this application are inconsistent or conflicting with the content of this application, the descriptions, definitions, and / or use of terms in this application shall prevail.

Claims

1. A busbar, characterized in that: It has a welding side and a back side which are arranged opposite to each other, the welding side is used for welding with a winding core (3), the back side is provided with a welding track (2), and the welding track (2) presents a smooth wavy curve; The welding track (2) comprises a plurality of semicircular portions (21) and a plurality of straight portions (22), and the plurality of semicircular portions (21) and the plurality of straight portions (22) are alternately arranged and connected in sequence.

2. The busbar according to claim 1, characterized in that: The plurality of straight line portions (22) are arranged in parallel and at intervals in sequence.

3. The busbar according to claim 1, characterized in that: The welding track (2) extends along the radial direction of the busbar.

4. The busbar according to claim 3, characterized in that: There are a plurality of welding tracks (2), and each welding track (2) is arranged in sequence around the center of the busbar.

5. The busbar according to claim 1, characterized in that: The busbar is a positive busbar, and the positive busbar comprises a busbar body (11) and a lead-out tab (12) extending from the busbar body (11).

6. The busbar according to claim 1, characterized in that: The welding track (2) presents a circular closed wave curve arranged around the center of the busbar.

7. The busbar according to claim 1, characterized in that: The thickness of the busbar is 0.1-0.5 mm.

8. A battery, characterized in that: It comprises a winding core (3) and a busbar according to any one of claims 1 to 7, wherein the welding side of the busbar is welded to the pole lug of the winding core (3), and the welding track (2) on the busbar overlaps the pole lug at the orthographic projection of the welding side.

9. The battery according to claim 8, characterized in that The winding core (3) includes a core portion and an outer peripheral surface formed by winding the first electrode, the second electrode and the separation membrane sandwiched therebetween around a winding axis as the center; The first electrode comprises an active material coated portion and an uncoated portion along the winding direction, at least a portion of the uncoated portion serves as an electrode tab, the uncoated portion comprises a first portion (A) adjacent to the core of the winding core (3), a second portion (B) adjacent to the outer peripheral surface of the winding core (3), and a third portion (C) between the first portion (A) and the second portion (B), and along the winding axis direction, the height of the first portion (A) and / or the second portion (B) is lower than the height of the third portion (C); The third portion (C) is divided into a plurality of segments (31) that can be bent individually, and the plurality of segments (31) form a bending surface area when bent along the radial direction of the winding core (3); the bending surface area is the pole ear of the winding core (3); Along the direction from the core side to the peripheral side, the bending surface area includes a uniform stacking number interval and a stacking number reduction interval, the stacking number of the section (31) in the uniform stacking number interval is uniform, the stacking number of the section (31) in the stacking number reduction interval is located outside the uniform stacking number interval, and the stacking number of the section (31) in the stacking number reduction interval decreases as approaching the peripheral side.

10. The battery according to claim 9, characterized in that The stacking number of the sections (31) in the uniform stacking number interval is more than 10 layers.

11. The battery according to any one of claims 9 or 10, characterized in that: The projection area of ​​the welding track (2) on the bending surface area is completely located within the uniform interval of the stacking number.

12. The battery according to any one of claims 9 or 10, characterized in that: The width of the welding track (2) is greater than the width of the section (31).

13. The battery according to any one of claims 9 or 10, characterized in that: Along the radial direction of the winding core, the welding track (2) is at least partially welded to two adjacent sections (31) in the same circle.

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