Cylindrical battery and collector plate thereof

Abstract

The invention discloses a cylindrical battery and a collector plate thereof, the collector plate comprises: a first welding portion located at the center, the first welding portion having a first plane and a second plane opposite to each other, the first plane being used for welding with a steel shell; the second welding part is located on the peripheral side of the first welding part and provided with a third plane and a fourth plane which are opposite, the third plane and the first plane are located on the same side, the fourth plane and the second plane are located on the same side, and the fourth plane is used for being welded to a roll core; the first plane protrudes out of the third plane; a hollow area is formed between the first welding part and the second welding part; the plurality of connecting parts are used for connecting the first welding part and the second welding part; the total length of the connecting part is greater than the width of the hollow area along the radial direction of the collector plate; and the connecting part can be deformed to reduce or zero the distance between the first plane and the third plane. The collector plate can provide more capacity space for a battery cell, and has the characteristics of assemblability and roller resistance.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a cylindrical battery and a current collector thereof. Background Art

[0002] With the development of battery technology, the requirements for the volume energy density and mechanical structure reliability of battery cells are becoming more and more stringent. High volume energy density means that the electrode structure accounts for a large proportion, which inevitably leads to a small proportion of the remaining structure space.

[0003] The full-ear design has seen a spurt in the design of winding cores, collector plates, shells and their connections. The collector plate is an important component in the full-ear structure, which serves to connect the winding core to one pole of the cylindrical battery shell. For the collector plate, in order to achieve process assemblability and anti-roll characteristics, the larger the design space required, the better, which is in contradiction with the above-mentioned "the remaining structural space accounts for a small proportion". Summary of the invention

[0004] In view of the deficiencies in the prior art, an object of this specification is to provide a cylindrical battery and a current collector plate thereof, which can provide more capacity space for the battery cell and has assembly and anti-roll characteristics.

[0005] To achieve the above-mentioned purpose, the embodiment of the present specification provides a current collecting plate of a cylindrical battery, which is used to be installed at the bottom of the cylindrical battery and welded to the steel shell and the winding core of the cylindrical battery respectively; the current collecting plate includes: A first welding portion located at the center, the first welding portion having a first plane and a second plane opposite to each other, the first plane being used for welding with the steel shell; a second welding portion located at a peripheral side of the first welding portion, the second welding portion having a third plane and a fourth plane opposite to each other, the third plane and the first plane being located at the same side, the fourth plane and the second plane being located at the same side, the fourth plane being used for welding with the winding core; the first plane protruding from the third plane, the fourth plane protruding from the second plane; a hollow area being formed between the first welding portion and the second welding portion; A plurality of connection parts are arranged in the hollow area, and are used to connect the first welding part and the second welding part; the total length of the connection parts is greater than the width of the hollow area along the radial direction of the collecting disk; the connection parts can be deformed to reduce the distance between the first plane and the third plane or make it zero.

[0006] As a preferred implementation, the total length of the connecting portion is greater than or equal to twice the width of the hollow area along the radial direction of the collecting disk.

[0007] As a preferred embodiment, the connecting portion includes a first connecting segment, a second connecting segment and a third connecting segment, the first connecting segment is connected to the first welding portion and is coplanarly arranged with the first welding portion, the third connecting segment is connected to the second welding portion and is coplanarly arranged with the second welding portion, and the second connecting segment is connected between the first connecting segment and the third connecting segment.

[0008] As a preferred embodiment, the angle between the third connecting segment and the inner diameter circle of the second welding portion is an acute angle and / or the first connecting segment is tangent to the outer diameter circle of the second welding portion, and on the first plane or the third plane, the first connecting segment and its extension line intersect with the third connecting segment and its extension line.

[0009] As a preferred implementation, on the first plane or the third plane, the second connecting segment and the third connecting segment are colinear, and an angle between the second connecting segment and the first connecting segment is 90°.

[0010] As a preferred implementation manner, there is a height difference between the first connecting section and the third connecting section, and the height difference is less than or equal to 3 times the thickness of the first welding portion.

[0011] As a preferred implementation, the length of the second connecting segment accounts for 0.1-0.8 of the total length of the connecting portion.

[0012] As a preferred implementation manner, the area of ​​the fourth plane of the second welding portion is greater than or equal to 80% of the area of ​​the collecting plate.

[0013] As a preferred implementation, the inner diameter of the second welding portion is less than or equal to 1 / 3 of the outer diameter of the second welding portion.

[0014] As a preferred implementation manner, the collecting plate is an integral piece, and the thickness of the second welding portion is equal to the thickness of the first welding portion.

[0015] As a preferred embodiment, the central axis of the first welding portion and the central axis of the second welding portion are collinear; and the plurality of connecting portions are evenly spaced in the circumferential direction.

[0016] As a preferred implementation, the number of the connecting parts is 2 to 4.

[0017] The embodiments of this specification provide a cylindrical battery, including: Steel shell; A winding core disposed within the steel shell; A first current collecting plate, wherein the first current collecting plate adopts the current collecting plate described in any of the above embodiments; one side of the first current collecting plate is welded to the bottom of the steel shell, and the other side is welded to the end face of the winding core; a second current collecting plate connected to the other end surface of the winding core; A cap is arranged on a side of the second current collecting disk away from the winding core.

[0018] Beneficial Effects

[0019] The current collector of the cylindrical battery provided in this embodiment is provided with a first plane of the first welding part protruding from the third plane of the second welding part, that is, the area in the center of the current collector for welding with the bottom of the steel shell is raised to form a small boss higher than the collective. When assembled, the small boss faces downward to ensure that the current collector and the bottom of the steel shell are well fitted when welded, thereby achieving a good welding effect and making the current collector have good assemblability. When welding the current collector and the steel shell, the small boss is beneficial to the welding of the metal steel shell of the bottom battery.

[0020] At the same time, when the battery cell is assembled, the connection part can be deformed to reduce or reduce the distance between the first plane and the third plane to 0, that is, after the battery cell is packaged, the force of the winding core squeezing the collector plate will cause the connection part to deform, so that the above-mentioned small bosses can be spread out to form a flat structure, and the first welding part and the second welding part can be compressed to be close to or in the same plane, providing more capacity space for the battery cell, improving the battery space energy density, and meeting the high-capacity design requirements. The connection part can be deformed and can be regarded as a soft connection, which has the effect of anti-rotation and anti-vibration. In the roller test, the connection part can be used as an energy buffer area for the impact work transmission, reducing the fracture caused by the rigid connection of the two welding areas, so that the collector plate has anti-roll characteristics.

[0021] With reference to the following description and the accompanying drawings, the specific embodiments of the present invention are disclosed in detail, indicating the manner in which the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope thereby.

[0022] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0023] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 A schematic diagram of the three-dimensional structure of a current collecting plate of a cylindrical battery provided in this embodiment; Figure 2 for Figure 1 A front view of Figure 3 for Figure 1 Dorsal view of; Figure 4 for Figure 1 Left view of Figure 5 A schematic diagram of the structure of a cylindrical battery provided in this embodiment; Figure 6 for Figure 5 A schematic diagram of the structure of the middle winding core and the first current collecting disk; Figure 7 for Figure 5 A schematic diagram of a welding trajectory between the middle winding core and the first current collecting plate; Figure 8 for Figure 5 Schematic diagram of another welding trajectory of the middle winding core and the first current collecting plate; Fig. 9 for Figure 5 Schematic diagram of the welding trajectory of the middle steel shell and the first collecting plate.

[0026] Description of reference numerals: 1. First welding part; 11. First plane; 12. Second plane; 2. Second welding part; 21. Third plane; 22. Fourth plane; 3. Hollow area; 4. Connecting part; 41. First connecting section; 42. Second connecting section; 43. Third connecting section; 5. Cylindrical battery; 51. Steel shell; 511. Bottom; 512. Side wall; 52. Winding core; 521. End face; 522. Center hole; 53. First current collecting disk; 54. Second current collecting disk; 55. Cap; 61. First welding track; 62. Second welding track; 63. Third welding track. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0028] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be another element centered thereon. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be another element centered thereon at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] See also Figures 1 to 4 The embodiment of the present application provides a current collecting plate of a cylindrical battery 5, which is installed at the bottom of the cylindrical battery 5 and welded to the steel shell 51 and the winding core 52 of the cylindrical battery 5. The current collecting plate includes a first welding portion 1, a second welding portion 2 and a plurality of connecting portions 4.

[0031] Among them, the first welding part 1 is located in the center. Figure 2 and Figure 3 As shown, the first welding portion 1 has a first plane 11 and a second plane 12 opposite to each other, and the first plane 11 is used for welding with the steel shell 51. The second welding portion 2 is located on the periphery of the first welding portion 1. The second welding portion 2 has a third plane 21 and a fourth plane 22 opposite to each other, the third plane 21 and the first plane 11 are located on the same side, the fourth plane 22 and the second plane 12 are located on the same side, and the fourth plane 22 is used for welding with the winding core 52. Figure 4As shown, the first plane 11 protrudes from the third plane 21, and the fourth plane 22 protrudes from the second plane 12. A hollow area 3 is formed between the first welding portion 1 and the second welding portion 2. A plurality of connecting portions 4 are arranged in the hollow area 3 for connecting the first welding portion 1 and the second welding portion 2. One end of the connecting portion 4 is connected to the first welding portion 1, and the other end is connected to the second welding portion 2. The total length of the connecting portion 4 is greater than the width of the hollow area 3 along the radial direction of the collector disk, that is, at least part of the connecting portion 4 does not extend along the radial direction of the collector disk, and the connecting portion 4 has a portion perpendicular to the radial direction of the collector disk to facilitate the deformation of the connecting portion 4. The connecting portion 4 can be deformed so that the distance between the first plane 11 and the third plane 21 is reduced or is 0.

[0032] Due to the preparation method, the first welding part 1 and the second welding part 2 can be made by integral stamping, so the thickness of the first welding part 1 and the second welding part 2 are preferably equal. In addition, if other preparation methods are used, the thickness relationship of the first welding part 1 and the second welding part 2 is acceptable for the present invention, for example, the thickness of the first welding part 1 is greater than or less than the thickness of the second welding part 2, and the technical effect of the present invention can be achieved.

[0033] The conventional collector plate on the market is a completely flat structure. This structure causes the flatness of the collector plate to deteriorate due to the effect of welding thermal stress after the periphery of the collector plate and the winding core tab are welded. As a result, when the center part is welded to the bottom of the battery metal steel shell, the contact is poor, or other reasons lead to technical problems such as cold welding and poor welding.

[0034] The current collector of the cylindrical battery 5 provided in this embodiment is provided with the first plane 11 of the first welding part 1 protruding from the third plane 21 of the second welding part 2, that is, the area in the center of the current collector for welding with the bottom 511 of the steel shell is raised to form a small boss higher than the collective. When assembling, the small boss is downward, ensuring that the current collector and the bottom 511 of the steel shell are well fitted when welded, thereby achieving a good welding effect, and making the current collector have good assemblability. When welding the current collector and the steel shell 51, the small boss is conducive to welding the metal steel shell 51 of the bottom battery.

[0035] However, the small boss design of the current collector is in conflict with the demand for a thinner current collector resulting from the cell capacity space. The present application sets the connection portion 4 to be deformable, so that the distance between the first plane 11 and the third plane 21 is reduced or becomes 0, that is, after the cell is packaged, the force of the winding core 52 squeezing the current collector will cause the connection portion 4 to deform, so that the above-mentioned small boss can be spread out to form a flat structure, and the first welding portion 1 and the second welding portion 2 can be compressed to be close to or in the same plane, providing more capacity space for the cell, improving the energy density of the battery space, and meeting the high-capacity design requirements. That is, the present application designs the shape of the current collector in different states (the current collector is designed to have a small boss structure in the assembly stage, and the current collector forms a flat structure after the cell is packaged), so that the current collector has good assemblability while also meeting the high-capacity design requirements.

[0036] In addition, the connection part 4 can produce deformation and can be regarded as a soft connection, which has the effect of anti-rotation and anti-vibration. In the roller test, the connection part 4 can be used as an energy buffer area for the impact work transmission, reducing the fracture caused by the rigid connection between the two welding areas, so that the collecting plate has anti-roller characteristics. In this embodiment, the collecting plate is an integral part and can be processed and manufactured as a whole, so as to facilitate the production and ensure the structural strength. The material of the connection part 4 is consistent with the first welding part 1 and the second welding part 2. The thickness of the second welding part 2 is equal to the thickness of the first welding part 1.

[0037] Specifically, the central axis of the first welding portion 1 and the central axis of the second welding portion 2 are collinear, that is, the first welding portion 1 and the second welding portion 2 are concentrically arranged. The plurality of connecting portions 4 are evenly spaced in the circumferential direction to ensure reliable connection strength.

[0038] Preferably, the number of the connecting parts 4 is 2 to 4, so as to avoid that too many connecting parts 4 occupy too much space in the hollow area 3, thereby affecting the deformation of the connecting parts 4 and causing the collector plate to be not earthquake-resistant; too few connecting parts 4 cannot achieve the technical effect of the present invention. The preferred method of the present invention is to use three connecting parts 4.

[0039] In this embodiment, the total length of the connection portion 4 is greater than or equal to twice the width of the hollow area 3 along the radial direction of the collector. The width of the hollow area 3 along the radial direction of the collector is equal to 1 / 2 of the difference between the inner diameter (inside diameter) of the second welding portion 2 and the outer diameter (diameter) of the first welding portion 1. The connection portion 4 provided in the hollow area 3 adopts a pseudo-flexible connection method, and its flexible connection effect is related to the connection cross-sectional area and the connection length. For example, if the cross-sectional area of ​​a metal wire is small enough and the length is long enough, the metal wire can be regarded as a flexible material; when the length of the material and the diameter equivalent to the cross-sectional area are closer, the rigidity of the material becomes greater and greater. Therefore, setting the length of the connection portion 4 to be greater than or equal to 3 times the width of the hollow area 3 can ensure that the connection portion 4 has a good flexible connection effect, so that the collector has a good seismic effect.

[0040] like Figure 1 and Figure 2 As shown, the connecting portion 4 includes a first connecting segment 41, a second connecting segment 42 and a third connecting segment 43. In a natural state (the natural state refers to the state before the battery is assembled), the first connecting segment 41 is connected to the first welding portion 1 and is coplanarly arranged with the first welding portion 1, the third connecting segment 43 is connected to the second welding portion 2 and is coplanarly arranged with the second welding portion 2, and the second connecting segment 42 is connected between the first connecting segment 41 and the third connecting segment 43. There is a certain height difference between the first connecting segment 41 and the third connecting segment 43.

[0041] Preferably, the height difference between the first connecting section 41 and the third connecting section 43 is less than or equal to 3 times the thickness of the first welding portion 1. If the height difference between the first connecting section 41 and the third connecting section 43 is too large, when the battery cell is sealed, the collector plate will require too much space for the second connecting section 42 to unfold under the deadweight of the winding core 52 and the axial pressure of the sealing roller groove, and the hollow area 3 cannot meet its space requirement, which will cause the second connecting section 42 to be unable to unfold, affecting the quality of the battery cell and causing the product to fail to meet the requirements.

[0042] In this embodiment, the length of the second connecting segment 42 accounts for 0.1 to 0.8 of the total length of the connecting portion 4. The length of the second connecting segment 42 cannot be too short. As analyzed above, a too short length will cause the rigidity of the connecting portion 4 to be too large, thereby not having the effect of flexible connection. In addition, the connecting portion 4 needs to reserve a certain length as the first connecting segment 41 and the third connecting segment 43 to ensure the connection strength between the connecting portion 4 and the first welding portion 1 and the second welding portion 2. The longer second connecting segment 42 mainly plays the role of flexible connection.

[0043] The second connecting section 42 may adopt a linear structure, so that the projections of the second connecting section 42 and the first connecting section 41 on the first plane 11 or the third plane 21 have an angle. As another embodiment, the second connecting section 42 may also adopt an arc design, so that the second connecting section 42 and the first connecting section 41 may also be smoothly connected (not shown in the figure).

[0044] As another embodiment, in the projection of the connecting portion 4 on the first plane 11 or the third plane 21 , the second connecting segment 42 and the third connecting segment 43 are colinear.

[0045] As an embodiment, when viewed from the side of the battery cell, the second connecting section 42 is substantially in a straight line shape.

[0046] As an embodiment, the connection parts between the second connection section 42 and the first connection section 41 and the third connection section 43 may be bent connections, and their connection parts have obvious bending angles.

[0047] As an embodiment, the connection parts between the second connection segment 42 and the first connection segment 41 and the third connection segment 43 can be connected in an arc shape, so that the transition of the connection point is softer, but the second connection segment 42 and the first connection segment 41 and the third connection segment 43, except for the connection points, are generally straight lines.

[0048] As another embodiment, when viewed from a direction perpendicular to the collecting plate (i.e., on the first plane 11 or the third plane 21), the second connecting segment 42 and the first connecting segment 41 have a certain angle when connected, such as a right angle (90°). This arrangement enables the second connecting segment 42 to be connected to the first welding portion 1 through the first connecting segment 41 when it is about to touch the second welding portion 2, thereby avoiding touching the second welding portion 2, and to be connected to the second welding portion 2 through the third connecting segment 43.

[0049] As another embodiment, the three first connection segments 41 are led out in a manner tangent to the outer diameter circle of the first welding portion 1, and the three first connection segments 41 are led out from the first welding portion 1 in the same direction (clockwise or counterclockwise). When the three first connection segments 41 (seen from a direction perpendicular to the collector plate) are about to contact the second welding portion 2, they are connected to the corresponding second connection segments 42 at right angles, and the connection direction is the side away from the second welding portion 2. Finally, the second connection segment 42 is connected to the third connection segment 43 and finally contacts the second welding portion 2. The angle between the third connection segment 43 and the inner diameter circle of the second welding portion 2 is an acute angle. On the first plane 11 or the third plane 21, the first connection segment 41 and its extension line intersect with the third connection segment 43 and its extension line.

[0050] As another embodiment, the entire connecting portion 4 is located in the hollow area 3, and the two ends of the connecting portion 4 are in contact with the first welding portion 1 and the second welding portion 2 respectively. The connecting portions 4 are preferably three, and are arranged at intervals of 120° from each other. The dimensions of the three connecting portions 4 are exactly the same. The battery cell roller test is an important indicator of the battery cell's ability to resist mechanical damage. Since the welding of the collector plate and the winding core 52 and the welding of the collector plate and the bottom 511 of the steel shell are affected by the welding process, when the energy output of the welding machine is too large, the structure of the winding core 52 will be destroyed. When the welding energy is too small, the welding is prone to cold welding. The welding process window is very narrow, and the anti-rolling ability of the internal connection structure of the battery cell must be ensured under the smaller tensile force of the welding of the collector plate with the winding core 52 and the steel shell 51. The present application sets a connection portion 4 that can generate deformation to connect the first welding portion 1 and the second welding portion 2. In the roller test, the connection portion 4 can be used as an energy buffer area for the transmission of impact energy to reduce the fracture caused by the rigid connection of the two welding areas.

[0051] The first welding part 1 and the second welding part 2 of the collector disk derived from the anti-rolling performance of the battery cell adopt a flexible connection, which requires sufficient space isolation between the first welding part 1 and the second welding part 2 on the collector disk. However, the process design of the battery cell requires the collector disk to provide more welding area to ensure sufficient welding tension, so the welding area between the collector disk and the winding core 52 needs to be as large as possible, which leads to a smaller isolation space between the first welding part 1 and the second welding part 2, which is inconsistent with the aforementioned "sufficient space isolation between the first welding part 1 and the second welding part 2". In order to resolve this contradiction, the present application reduces the area of ​​the connection part 4 and sets the first welding part 1 in the central area of ​​the collector disk. In addition, the connection part 4 can be narrowed and elongated.

[0052] In this embodiment, the area of ​​the fourth plane 22 of the second welding portion 2 is greater than or equal to 80% of the area of ​​the collecting disk, thereby ensuring that the welding area between the collecting disk and the winding core 52 is as large as possible to ensure sufficient welding tension.

[0053] In one embodiment, the inner diameter of the second welding portion 2 is less than or equal to 1 / 3 of the outer diameter of the second welding portion 2, thereby ensuring that the second welding portion 2 has a sufficiently large welding area.

[0054] Based on the same concept, the present invention also provides a cylindrical battery 5 in the embodiment, as described in the following embodiment. Since the principle of solving the problem and the technical effect that can be achieved by the cylindrical battery 5 are similar to those of the above-mentioned current collecting plate, the implementation of the cylindrical battery 5 can refer to the implementation of the above-mentioned current collecting plate, and the repeated parts will not be repeated.

[0055] See also Figures 5 to 9One embodiment of the present invention further provides a cylindrical battery 5, comprising: a steel shell 51, a winding core 52, a first current collecting disc 53, a second current collecting disc 54 and a cap 55. The winding core 52 is disposed in the steel shell 51. The first current collecting disc 53 is a current collecting disc as described in any of the above embodiments. Figures 6 to 9 As shown, one side (fourth plane 22) of the first current collecting plate 53 is welded to the bottom 511 of the steel shell, and the other side (first plane 11) is welded to the end face 521 of the winding core. The second current collecting plate 54 is connected to the other end face of the winding core 52. The cap 55 is arranged on the side of the second current collecting plate 54 away from the winding core 52.

[0056] The winding core 52 has a central hole 522, one end face 521 of the winding core 52 is welded to the first current collecting plate 53, and the other end face is connected to the second current collecting plate 54. The steel shell 51 has a bottom 511 and a side wall 512, and the bottom 511 of the steel shell is welded to the first current collecting plate 53 (using a method such as Fig. 9 As shown in the third circular welding track 63 , the steel shell side wall 512 surrounds the winding core 52 .

[0057] It should be noted that the steel shell 51, the winding core 52, the second current collecting plate 54, and the cap 55 of the cylindrical battery 5 provided in this embodiment can be selected from any suitable existing structures. In order to clearly and briefly explain the technical solution provided in this embodiment, the above parts will not be repeated here, and the drawings in the specification are also simplified accordingly. However, it should be understood that the scope of this embodiment is not limited by this.

[0058] In a specific application scenario, for a formed full-tab type winding core 52, the full-tab type winding core 52 includes a flattened full-tab winding core and a flattened full-tab winding core with a groove, the first collector plate 53 is made coaxial with the winding core 52 by a jig, and the fourth plane 22 of the first welding portion 1 of the first collector plate 53 is made close to the winding core end surface 521, and the first collector plate 53 is made coaxial with the first welding portion 1 of the first collector plate 53. Figure 7 or Figure 8 Since the area of ​​the fourth plane 22 in the present application accounts for more than 80% of the total area of ​​the first collector plate 53, and the welding area between the first collector plate 53 and the winding core 52 (i.e., the fourth plane 22) is a continuous, uninterrupted annular belt area, there are a large number of options for the welding form and welding trajectory of the winding core 52 and the first collector plate 53 (such as Figure 7 The first straight welding track 61 shown in FIG. Figure 8 In addition, the design of this welding area is compatible with the first collecting plate 53 when it is adapted to the winding core end surface 521 formed in different ways.

[0059] After welding the first current collecting disk 53, the winding core 52 is assembled into the shell with the first plane 11 of the first current collecting disk 53 facing the bottom 511 of the steel shell. Since the first plane 11 protrudes from the third plane 21, the first plane 11 of the first welding portion 1 first contacts the bottom 511 of the steel shell during the assembly process. This structural design provides a good contact state of the two welding interfaces for the battery cell process welding, ensuring that the first current collecting disk 53 and the bottom 511 of the steel shell have a good welding effect.

[0060] After the battery cell is sealed by the roller groove after being put into the shell, under the weight of the winding core 52 and the axial pressure of the sealing roller groove, the second connecting section 42 in the connecting part 4 of the first collecting plate 53 spreads out under the action of the axial force. Under the action of the gravity of the battery and the pressure of the internal equipment of the battery, the second welding part 2 sinks to a plane close to the first welding part 1, or makes the second welding part 2 and the first welding part 1 in the same plane, thereby reducing the space occupied by the first collecting plate 53 after assembly and increasing the capacity space.

[0061] When the drum test is performed, collisions occur between the cylindrical batteries 5 and inside the cylindrical batteries 5. Due to inertia, there is a certain relative movement between the internal structure composed of the internal winding core 52 and the first current collecting disk 53 and the external structure composed of the steel shell 51 and the cap 55. When the downward movement of the cap 55 end is blocked by collision, the winding core 52 moves toward the cap 55 end due to inertia, and during its movement, it pulls the second welding part 2 welded to it, so that the first current collecting disk 53 has a tendency to move toward the cap 55 end. A common form of failure in this process is that the two welding points between the first current collecting disk 53 and the winding core 52 and the first current collecting disk 53 and the steel shell 51 are broken due to force, resulting in failure of the battery cell drum. In this application, in order to avoid failure of the drum in this state, the following two designs are provided.

[0062] First, the first welding portion 1 and the second welding portion 2 of the first collecting plate 53 are provided with a height difference and are compressed under the axial extrusion force of assembly so that the two are in the same plane, but in this state, the axial extrusion force brought by the assembly structure is reduced, and the second welding portion 2 and the winding core 52 move toward the direction of the cap 55 and return to the structural state before being assembled. The boss design with a certain height difference between the first welding portion 1 and the second welding portion 2 provides a deformation for partial energy absorption at the welding position; Secondly, the first collecting plate 53 is designed with a hollow area 3 and a connecting portion 4. This simulated flexible connection design can provide a better kinetic energy absorption effect. When the original boss structure design cannot completely absorb the impact energy, the impact energy in the drum continues to be absorbed through the deformation of the connecting area.

[0063] The above two designs can effectively reduce the stress on the welding area by unloading the force during the roller test.

[0064] Before the current collecting disk provided by the present application is used, since the stress generated by the movement trend of the core end face 521 transmitted to the current collecting disk is mostly resisted by the rigidity of the two welding positions of the current collecting disk, the strength requirements at the two welding positions of the current collecting disk are relatively high. After the first current collecting disk 53 uses the current collecting disk provided by the present application, the deformation of the current collecting disk resists part of the impact stress, which reduces the demand for welding tension in the structural design and ensures the reliability of the roller battery structure of the battery cell.

[0065] It should be noted that, in the description of this specification, the terms "first", "second", etc. are only used for descriptive purposes and to distinguish similar objects. There is no order of precedence between the two, and they cannot be understood as indicating or implying relative importance. In addition, in the description of this specification, unless otherwise specified, the meaning of "plurality" is two or more.

[0066] Any numerical value cited herein includes all values ​​of lower and upper values ​​that increase by one unit from the lower limit to the upper limit, and there is at least a two-unit interval between any lower value and any higher value. For example, if the value of the quantity of a component or a process variable (such as temperature, pressure, time, etc.) is set forth to be from 1 to 90, preferably from 20 to 80, and more preferably from 30 to 70, the purpose is to illustrate that values ​​such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also explicitly listed in the specification. For values ​​less than 1, one unit is appropriately considered to be 0.0001, 0.001, 0.01, 0.1. These are merely examples that are intended to be clearly expressed, and it can be considered that all possible combinations of numerical values ​​listed between the lowest value and the highest value are clearly set forth in the specification in a similar manner.

[0067] Unless otherwise indicated, all ranges include the endpoints and all numbers between the endpoints. "About" or "approximately" used with a range applies to both endpoints of the range. Thus, "about 20 to 30" is intended to cover "about 20 to about 30", including at least the specified endpoints.

[0068] All articles and references disclosed, including patent applications and publications, are incorporated herein by reference for all purposes. The term "consisting essentially of..." to describe a combination should include the identified elements, ingredients, parts or steps and other elements, ingredients, parts or steps that do not substantially affect the basic novel characteristics of the combination. The use of the terms "comprising" or "including" to describe a combination of elements, ingredients, parts or steps herein also contemplates embodiments that consist essentially of these elements, ingredients, parts or steps. By using the term "may", it is intended to indicate that any attribute described that "may" include is optional.

[0069] Multiple elements, ingredients, parts or steps can be provided by a single integrated element, ingredient, part or step. Alternatively, a single integrated element, ingredient, part or step can be divided into separate multiple elements, ingredients, parts or steps. The disclosure "one" or "an" used to describe an element, ingredient, part or step is not intended to exclude other elements, ingredients, parts or steps.

[0070] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but should be determined with reference to the appended claims and the full scope of equivalents possessed by such claims. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of the subject matter, nor should it be considered that the inventors did not consider the subject matter to be part of the disclosed inventive subject matter.

Claims

1. A current collector for a cylindrical battery, which is installed at the bottom of the cylindrical battery and is welded to the steel shell and the winding core of the cylindrical battery respectively; characterized in that: The collecting plate comprises: A first welding portion located at the center, the first welding portion having a first plane and a second plane opposite to each other, the first plane being used for welding with the steel shell; a second welding portion located at a peripheral side of the first welding portion, the second welding portion having a third plane and a fourth plane opposite to each other, the third plane and the first plane being located on the same side, the fourth plane and the second plane being located on the same side, the fourth plane being used for welding with the winding core; the first plane protruding from the third plane, the fourth plane protruding from the second plane; a hollow area being formed between the first welding portion and the second welding portion; A plurality of connection parts are arranged in the hollow area, and are used to connect the first welding part and the second welding part. The total length of the connection parts is greater than the width of the hollow area along the radial direction of the collecting disk. The connection parts can be deformed to reduce the distance between the first plane and the third plane or make it zero.

2. The current collecting plate of a cylindrical battery according to claim 1, characterized in that: The total length of the connecting portion is greater than or equal to twice the width of the hollow area along the radial direction of the collecting disk.

3. The current collecting plate of a cylindrical battery according to claim 1, characterized in that: The connecting portion includes a first connecting segment, a second connecting segment and a third connecting segment, the first connecting segment is connected to the first welding portion and is coplanarly arranged with the first welding portion, the third connecting segment is connected to the second welding portion and is coplanarly arranged with the second welding portion, and the second connecting segment is connected between the first connecting segment and the third connecting segment.

4. The current collecting plate of the cylindrical battery according to claim 3, characterized in that: The angle between the third connecting section and the inner diameter circle of the second welding part is an acute angle and / or the first connecting section is tangent to the outer diameter circle of the second welding part, and on the first plane or the third plane, the first connecting section and its extension line intersect with the third connecting section and its extension line.

5. The current collecting plate of the cylindrical battery according to claim 4, characterized in that: On the first plane or the third plane, the second connecting segment and the third connecting segment are colinear, and an angle between the second connecting segment and the first connecting segment is 90°.

6. The current collecting plate of a cylindrical battery according to claim 3, characterized in that: There is a height difference between the first connecting section and the third connecting section, and the height difference is less than or equal to 3 times the thickness of the first welding portion; the length of the second connecting section accounts for 0.1-0.8 of the total length of the connecting portion.

7. The current collecting plate of a cylindrical battery according to claim 1, characterized in that: The area of ​​the fourth plane of the second welding portion is greater than or equal to 80% of the area of ​​the collecting plate; the inner diameter of the second welding portion is less than or equal to 1 / 3 of the outer diameter of the second welding portion.

8. The current collecting plate of a cylindrical battery according to claim 1, characterized in that: The collecting plate is an integral piece, and the thickness of the second welding portion is equal to the thickness of the first welding portion.

9. The current collecting plate of a cylindrical battery according to claim 8, characterized in that: The central axis of the first welding portion and the central axis of the second welding portion are collinear; the plurality of connecting portions are evenly spaced in the circumferential direction; and the number of the connecting portions is 2 to 4.

10. A cylindrical battery, characterized in that: include: Steel shell; A winding core disposed within the steel shell; A first current collecting plate, wherein the first current collecting plate is a current collecting plate as described in any one of claims 1 to 9; one side of the first current collecting plate is welded to the bottom of the steel shell, and the other side is welded to the end face of the winding core; a second current collecting plate connected to the other end surface of the winding core; A cap is arranged on a side of the second current collecting disk away from the winding core.

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