Cylindrical battery and its current collector plate

Abstract

The present application discloses a cylindrical battery and its current collector plate. The current collector plate includes: a first welding portion located at the center, the first welding portion having opposite first and second planes, the first plane being used for welding with the steel shell; a second welding portion located on the periphery of the first welding portion, the second welding portion having opposite third and fourth planes, the third plane and the first plane being on the same side, the fourth plane and the second plane being on the same side, the fourth plane being used for welding with the wound core; the first plane protruding from the third plane; a hollow area formed between the first welding portion and the second welding portion; a plurality of connecting portions for connecting the first welding portion and the second welding portion; the total length of the connecting portions being greater than the width of the hollow area in the radial direction of the current collector plate; the connecting portions being capable of deforming to reduce or make the distance between the first plane and the third plane zero. The current collector plate can provide more capacity space for the battery cell and has assembly feasibility and drum resistance characteristics at the same time.

Description

Technical Field

[0001] This specification relates to the technical field of batteries, and particularly to a cylindrical battery and its current collector plate. Background Art

[0002] With the development of battery technology, the requirements for the volumetric energy density and mechanical structure reliability of battery cells are becoming increasingly stringent. A high volumetric energy density means that the proportion of the electrode structure is relatively large, which will inevitably lead to a relatively small proportion of the remaining structural space.

[0003] The designs of full tab structures in the core, current collector plate, housing and their interconnections have grown explosively. The current collector plate is an important component in the full tab structure, which plays a role in connecting the core to one pole of the cylindrical battery housing. For the current collector plate, in order to achieve process assemblability and anti-rolling characteristics, the larger the design space required, the better, which conflicts with the above-mentioned "relatively small proportion of the remaining structural space". Summary of the Invention

[0004] In view of the deficiencies of the prior art, an object of this specification is to provide a cylindrical battery and its current collector plate, which can provide more capacity space for the battery cell and at the same time have assemblability and anti-rolling characteristics.

[0005] To achieve the above object, an embodiment of this specification provides a current collector plate for a cylindrical battery, which is used to be installed at the bottom of the cylindrical battery and is welded to the steel shell and the core of the cylindrical battery respectively; the current collector plate includes:

[0006] A first welding part located at the center, the first welding part having opposite first and second planes, the first plane being used for welding with the steel shell;

[0007] A second welding part located on the periphery of the first welding part, the second welding part having opposite third and fourth planes, the third plane and the first plane being on the same side, the fourth plane and the second plane being on the same side, the fourth plane being used for welding with the core; the first plane protrudes from the third plane, and the fourth plane protrudes from the second plane; a hollow area is formed between the first welding part and the second welding part;

[0008] A plurality of connecting parts arranged in the hollow area for connecting the first welding part and the second welding part; the total length of the connecting parts is greater than the width of the hollow area in the radial direction of the current collector plate; the connecting parts can deform to reduce or make the distance between the first plane and the third plane zero.

[0009] As a preferred embodiment, the total length of the connecting parts is greater than or equal to 2 times the width of the hollow area in the radial direction of the current collector plate.

[0010] 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 coplanar with the first welding portion. The third connecting segment is connected to the second welding portion and is coplanar with the second welding portion. The second connecting segment is connected between the first connecting segment and the third connecting segment.

[0011] As a preferred embodiment, the included 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 in 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.

[0012] As a preferred embodiment, in the first plane or the third plane, the second connecting segment is collinear with the third connecting segment, and the included angle between the second connecting segment and the first connecting segment is 90°.

[0013] As a preferred embodiment, there is a height difference between the first connecting segment and the third connecting segment, and the height difference is less than or equal to 3 times the thickness of the first welding portion.

[0014] As a preferred embodiment, the length of the second connecting segment accounts for 0.1 to 0.8 of the total length of the connecting portion.

[0015] As a preferred embodiment, the area of the fourth plane of the second welding portion is greater than or equal to 80% of the area of the current collector plate.

[0016] As a preferred embodiment, 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.

[0017] As a preferred embodiment, the current collector plate is a single-piece body, and the thickness of the second welding portion is equal to the thickness of the first welding portion.

[0018] As a preferred embodiment, the central axes of the first welding portion and the second welding portion are collinear; a plurality of the connecting portions are arranged at equal intervals in the circumferential direction.

[0019] As a preferred embodiment, the number of the connecting portions is 2 to 4.

[0020] The embodiments of this specification provide a cylindrical battery, including:

[0021] A steel shell;

[0022] A wound core disposed within the steel shell;

[0023] The first current collector plate, where the first current collector plate adopts the current collector plate described in any of the above embodiments; one side of the first current collector plate is welded to the bottom of the steel shell, and the other side is welded to the end face of the core;

[0024] The second current collector plate, which is connected to the other end face of the core;

[0025] A cap provided on the side of the second current collector plate facing away from the core.

[0026] Advantageous effects

[0027] For the current collector plate of the cylindrical battery provided in this embodiment, by setting the first plane of the first welding part to protrude from the third plane of the second welding part, that is, the area at the center of the current collector plate for welding to the bottom of the steel shell protrudes to form a small boss higher than the collective. During assembly, the small boss faces downward to ensure good fitting when the current collector plate is welded to the bottom of the steel shell, thereby achieving a good welding effect and enabling the current collector plate to have good assemblability. When welding the current collector plate and the steel shell, due to the presence of the small boss, it is beneficial for welding the metal steel shell at the bottom of the battery.

[0028] At the same time, when the battery core is assembled, the connecting part can deform to reduce or make the distance between the first plane and the third plane zero. That is, after the battery core is encapsulated, the force exerted by the core on the current collector plate will cause the connecting part to deform, so that the above-mentioned small boss 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 core, improving the space energy density of the battery, and meeting the high-capacity design requirements. The connecting part can deform, which can be regarded as a soft connection and has the effects of anti-rotation and anti-vibration. In the drum test, the connecting part can serve as an energy buffer area for impact work transfer, reducing the fracture caused by the rigid connection of the two welding areas, making the current collector plate have anti-drum characteristics.

[0029] Referring to the following description and the drawings, specific embodiments of the present invention are disclosed in detail, indicating the ways 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.

[0030] Features described and / or illustrated for one embodiment can be used in the same or similar way in one or more other embodiments, combined with the features in other embodiments, or replace the features in other embodiments.

[0031] It should be emphasized that the term "comprising / including" when used herein refers to the presence of features, whole things, steps or components, but does not exclude the presence or addition of one or more other features, whole things, steps or components. Description of the drawings

[0032] 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 skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0033] Figure 1 Schematic perspective view of a current collector plate of a cylindrical battery provided in this embodiment;

[0034] Figure 2 is Figure 1 front view of;

[0035] Figure 3 is Figure 1 rear view of;

[0036] Figure 4 is Figure 1 left view of;

[0037] Figure 5 Schematic structural view of a cylindrical battery provided in this embodiment;

[0038] Figure 6 is Figure 5 schematic structural view of the core and the first current collector plate in;

[0039] Figure 7 is Figure 5 schematic diagram of a welding track of the core and the first current collector plate in;

[0040] Figure 8 is Figure 5 another schematic diagram of a welding track of the core and the first current collector plate in;

[0041] Figure 9 is Figure 5 schematic diagram of a welding track of the steel shell and the first current collector plate in.

[0042] Explanation of reference numerals:

[0043] 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. Core; 521. End face; 522. Central hole; 53. First current collector plate; 54. Second current collector plate; 55. Cap; 61. First welding track; 62. Second welding track; 63. Third welding track. Detailed implementation manners

[0044] 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 accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0045] It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there can also be another intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be another intermediate element 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 manner.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein 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 of the related listed items.

[0047] Please refer to Figures 1 to 4 The embodiment of the present application provides a current collector plate for a cylindrical battery 5, which is used to be installed at the bottom of the cylindrical battery 5 and is welded to the steel shell 51 and the wound core 52 of the cylindrical battery 5 respectively. The current collector plate includes a first welding portion 1, a second welding portion 2 and a plurality of connecting portions 4.

[0048] Among them, the first welding portion 1 is located at the center. As Figure 2 and Figure 3 shown, the first welding portion 1 has opposite first plane 11 and second plane 12, and the first plane 11 is used to be welded to 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 opposite third plane 21 and fourth plane 22. The third plane 21 and the first plane 11 are on the same side, and the fourth plane 22 and the second plane 12 are on the same side. The fourth plane 22 is used to be welded to the wound core 52. As 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 part 1 and the second welding part 2. A plurality of connecting parts 4 are arranged in the hollow area 3 for connecting the first welding part 1 and the second welding part 2. One end of the connecting part 4 is connected to the first welding part 1, and the other end is connected to the second welding part 2. The total length of the connecting part 4 is greater than the width of the hollow area 3 in the radial direction of the current collector plate, that is, at least part of the connecting part 4 does not extend along the radial direction of the current collector plate, and the connecting part 4 has a part perpendicular to the radial direction of the current collector plate to facilitate the deformation of the connecting part 4. The connecting part 4 can generate deformation to reduce or make the distance between the first plane 11 and the third plane 21 zero.

[0049] Due to the preparation method, the first welding part 1 and the second welding part 2 can be made by integral stamping. In this way, the thicknesses of the first welding part 1 and the second welding part 2 are preferably equal. Additionally, if other preparation methods are adopted, the thickness relationship between the first welding part 1 and the second welding part 2 is acceptable for the present invention. For example, the technical effects of the present invention can be achieved when the thickness of the first welding part 1 is greater than or less than the thickness of the second welding part 2.

[0050] The conventional current collector plate on the market is a structure of a whole plane. This structure causes that after the periphery of the current collector plate is welded to the tab of the core, due to the action of welding thermal stress, the flatness of the current collector plate becomes poor. Therefore, when the central part is welded to the bottom of the battery metal steel shell, there is poor contact, or other reasons lead to technical problems such as virtual welding and poor welding during welding.

[0051] For the current collector plate of the cylindrical battery 5 provided in this embodiment, by setting the first plane 11 of the first welding part 1 to protrude from the third plane 21 of the second welding part 2, that is, the area of the current collector plate center for welding to the bottom 511 of the steel shell protrudes to form a small boss higher than the collective. During assembly, the small boss faces downward to ensure good fitting when the current collector plate is welded to the bottom 511 of the steel shell, thereby achieving a good welding effect and enabling the current collector plate to have good assemblability. When welding the current collector plate and the steel shell 51, due to the presence of the small boss, it is beneficial for welding the bottom battery metal steel shell 51.

[0052] However, the design of the small boss on the current collector plate conflicts with the requirement of thinning the current collector plate derived from the cell capacity space. In this application, the connecting portion 4 is provided 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 encapsulated, the force exerted by the wound core 52 on the current collector plate will cause the connecting portion 4 to deform, so that the above-mentioned small boss can be unfolded 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 space energy density of the battery, and meeting the high-capacity design requirements. That is, in this application, by designing the shape of the current collector plate in different states (designing the current collector plate to have a small boss structure during the assembly stage, and the current collector plate forming a flat structure after the cell is encapsulated), while the current collector plate has good assemblability, it can also meet the high-capacity design requirements.

[0053] In addition, the connecting portion 4 can be deformed, which can be regarded as a soft connection and has the effects of anti-rotation and anti-vibration. In the drum test, the connecting portion 4 can serve as an energy buffer area for impact work transmission, reducing the fracture caused by the rigid connection of the two welding areas, so that the current collector plate has anti-drum characteristics. In this embodiment, the current collector plate is a one-piece body and can be integrally processed, which is convenient for manufacturing and ensures the structural strength. The material of the connecting portion 4 is the same as that of the first welding portion 1 and the second welding portion 2. The thickness of the second welding portion 2 is equal to the thickness of the first welding portion 1.

[0054] Specifically, the central axes of the first welding portion 1 and the second welding portion 2 are collinear, that is, the first welding portion 1 and the second welding portion 2 are concentrically arranged. A plurality of connecting portions 4 are evenly spaced in the circumferential direction to ensure reliable connection strength.

[0055] Preferably, the number of the connecting portions 4 is 2 to 4, to avoid excessive number occupying too much space in the hollow area 3, thus affecting the deformation of the connecting portion 4 and resulting in the current collector plate not having earthquake resistance; too few numbers cannot achieve the technical effects in the present invention. The preferred way in the present invention is to adopt 3 connecting portions 4.

[0056] In this embodiment, the total length of the connecting portion 4 is greater than or equal to twice the width of the hollowed-out area 3 in the radial direction of the current collector plate. The width of the hollowed-out area 3 in the radial direction of the current collector plate is equal to half of the difference between the inner diameter (inner side diameter) of the second welding portion 2 and the outer diameter (diameter) of the first welding portion 1. The connecting portion 4 provided in the hollowed-out area 3 adopts a flexible connection-like method, and its flexible connection effect is related to the connection cross-sectional area and the connection length. For example, for a metal wire, if the cross-sectional area of the metal wire is small enough and the length is long enough, the metal wire can be regarded as a flexible material; when the equivalent diameters of the length and cross-sectional area of the material are closer, the rigidity presented by the material is greater. Therefore, setting the length of the connecting portion 4 to be greater than or equal to three times the width of the hollowed-out area 3 can ensure that the connecting portion 4 has a good flexible connection effect, so that the current collector plate has a good seismic resistance effect.

[0057] As Figure 1 and Figure 2 shown, the connecting portion 4 includes a first connecting section 41, a second connecting section 42, and a third connecting section 43. In the natural state (the natural state refers to the state before battery assembly), the first connecting section 41 is connected to the first welding portion 1 and is coplanar with the first welding portion 1. The third connecting section 43 is connected to the second welding portion 2 and is coplanar with the second welding portion 2. The second connecting section 42 is connected between the first connecting section 41 and the third connecting section 43. There is a certain height difference between the first connecting section 41 and the third connecting section 43.

[0058] Preferably, the height difference between the first connecting section 41 and the third connecting section 43 is less than or equal to three 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 core is sealed, under the self-weight of the winding core 52 and the axial pressure of the sealing roller groove, the space required for the second connecting section 42 to spread out will be too large, and the hollowed-out area 3 cannot meet its space requirements, resulting in the second connecting section 42 being unable to spread out, affecting the quality of the battery core and causing the product to not meet the requirements.

[0059] In this embodiment, the length of the second connecting section 42 accounts for 0.1 to 0.8 of the total length of the connecting portion 4. The length of the second connecting section 42 cannot be too short. As analyzed above, if the length is too short, the rigidity of the connecting portion 4 will be too large, and thus it will not have a flexible connection effect. In addition, the connecting portion 4 needs to reserve a certain length as the first connecting section 41 and the third connecting section 43 to ensure the connection strength between the connecting portion 4 and the first welding portion 1 and the second welding portion 2. The relatively long second connecting section 42 mainly plays a role in flexible connection.

[0060] 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).

[0061] 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.

[0062] As an embodiment, when viewed from the side of the battery cell, the second connecting section 42 is substantially in a straight line shape.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] As another embodiment, the entire connecting portion 4 is located within the hollow area 3. The two ends of the connecting portion 4 are respectively in contact with the first welding portion 1 and the second welding portion 2. Preferably, there are 3 connecting portions 4, which are arranged at intervals of 120°. The sizes of the 3 connecting portions 4 are exactly the same. The cell drum test is an important indicator of the cell's resistance to mechanical damage. Due to the welding between the current collector plate and the core 52 and the welding between the current collector plate and the bottom 511 of the steel shell being affected by the welding process, when the energy output of the welding machine is too large, the structure of the core 52 will be damaged. When the welding energy is too small, the welding is prone to being a poor weld. The welding process window is very narrow, and it is necessary to ensure the anti-drum ability of the internal connection structure of the cell under the tensile force of the welding between the relatively small current collector plate and the core 52 and the steel shell 51. The present application provides a deformable connecting portion 4 to connect the first welding portion 1 and the second welding portion 2. During the drum test, the connecting portion 4 can serve as an energy buffer area for the transfer of impact work, reducing the fracture caused by the rigid connection between the two welding areas.

[0068] The flexible connection of the first welding portion 1 and the second welding portion 2 of the current collector plate derived from the cell's anti-drum performance requires sufficient space isolation between the first welding portion 1 and the second welding portion 2 on the current collector plate. However, the process design of the cell requires the current collector plate to provide more welding area to ensure sufficient welding tensile force. Then, the welding area between the current collector plate and the core 52 needs to be as large as possible, which in turn leads to the isolation space between the first welding portion 1 and the second welding portion 2 tending to be small, which conflicts with the aforementioned "sufficient space isolation between the first welding portion 1 and the second welding portion 2". To solve this contradiction, the present application reduces the area of the connecting portion 4 and arranges the first welding portion 1 in the central area of the current collector plate. In addition, the connecting portion 4 can be narrowed and elongated.

[0069] 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 current collector plate, so as to ensure that the welding area between the current collector plate and the core 52 is as large as possible to ensure sufficient welding tensile force.

[0070] 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, so as to ensure that the second welding portion 2 has a sufficiently large welding area.

[0071] Based on the same concept, an embodiment of the present invention also provides a cylindrical battery 5 as described in the following embodiments. Since the principle of solving problems and the technical effects that can be achieved by this cylindrical battery 5 are similar to those of the above current collector plate, the implementation of this cylindrical battery 5 can refer to the implementation of the above current collector plate, and the repeated parts will not be described again.

[0072] Please refer to Figures 5 to 9, an embodiment of the present invention further provides a cylindrical battery 5, including: a steel shell 51, a winding core 52, a first current collector plate 53, a second current collector plate 54, and a cap 55. The winding core 52 is disposed inside the steel shell 51. The first current collector plate 53 adopts the current collector plate described in any one of the above embodiments. As Figures 6 to 9 shown, one side (the fourth plane 22) of the first current collector plate 53 is welded to the bottom 511 of the steel shell, and the other side (the first plane 11) is welded to the end face 521 of the winding core. The second current collector plate 54 is connected to the other end face of the winding core 52. The cap 55 is disposed on the side of the second current collector plate 54 away from the winding core 52.

[0073] Among them, the winding core 52 has a central hole 522. One end face 521 of the winding core 52 is welded to the first current collector plate 53, and the other end face is connected to the second current collector plate 54. The steel shell 51 has a bottom 511 and a side wall 512. The bottom 511 of the steel shell is welded to the first current collector plate 53 (adopting the circular third welding track 63 as Figure 9 shown), and the side wall 512 of the steel shell surrounds the winding core 52.

[0074] It should be noted that the steel shell 51, the winding core 52, the second current collector plate 54, and the cap 55 of the cylindrical battery 5 provided in this embodiment can be selected from any suitable existing structures. To clearly and briefly illustrate the technical solution provided in this embodiment, the above parts will not be described in detail here, and the accompanying drawings of the specification have also been correspondingly simplified. However, it should be understood that the scope of this embodiment is not limited thereby.

[0075] In a specific application scenario, for the formed all-tab type winding core 52, the all-tab type winding core 52 includes a flattened all-tab winding core and a flattened all-tab winding core with grooves. A jig is used to coaxialize the first current collector plate 53 with the winding core 52, and make the fourth plane 22 of the first welding portion 1 of the first current collector plate 53 closely adhere to the end face 521 of the winding core. Through the welding method as Figure 7 or Figure 8 shown, the two components are connected. Since the area of the fourth plane 22 in this application accounts for more than 80% of the total area of the first current collector plate 53, and the welding area (i.e., the fourth plane 22) between the first current collector plate 53 and the winding core 52 is a continuous and unbroken annular band region, there are a large number of options for the welding form and the selection of the welding track between the winding core 52 and the first current collector plate 53 (such as the linear first welding track 61 as Figure 7 shown, the continuous dot-shaped second welding track 62 as Figure 8 shown). In addition, the design of this welding area can be used in a compatible manner when the first current collector plate 53 adapts to the end faces 521 of the winding cores formed in different ways.

[0076] After the core 52 of the first current collector plate 53 is welded, it is assembled into the shell with the first plane 11 of the first current collector plate 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 part 1 first contacts the bottom 511 of the steel shell during the assembly process. This structural design provides a good contact state between the two welding interfaces for the cell manufacturing process welding, ensuring a good welding effect between the first current collector plate 53 and the bottom 511 of the steel shell.

[0077] After the cell is sealed in the roller groove, under the self-weight of the core 52 and the axial pressure of the sealing roller groove, the second connecting section 42 in the connecting part 4 of the first current collector plate 53 unfolds under the axial force. Under the action of the battery gravity 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 the second welding part 2 and the first welding part 1 are in the same plane, reducing the space occupation ratio of the first current collector plate 53 after assembly and improving the capacity space.

[0078] During the drum test, 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 core 52 and the first current collector plate 53 and the external structure composed of the steel shell 51 and the cap 55. When the movement of the cap 55 end downward is blocked by a collision, the core 52 moves towards the cap 55 end due to inertia. During its movement, it pulls the second welding part 2 welded to it, causing the first current collector plate 53 to have a tendency to move towards the cap 55 end. The common failure form in this process is that the two welded joints between the first current collector plate 53 and the core 52 and between the first current collector plate 53 and the steel shell 51 are pulled and broken, resulting in the failure of the cell during the drum test. In this application, to avoid the drum failure in this state, there are the following two designs.

[0079] First, there is a height difference between the first welding part 1 and the second welding part 2 of the first current collector plate 53, and they are compressed under the axial extrusion force during assembly to be in the same plane. However, in this state, the axial extrusion force brought by the assembly structure decreases, and the second welding part 2 and the core 52 move towards the cap 55 and return to the structural state before being assembled. The design of the boss with a certain height difference between the first welding part 1 and the second welding part 2 provides a part of the deformation for energy absorption at the welded joint.

[0080] Second, the first current collector plate 53 is designed with a hollow area 3 and a connecting part 4. This design imitating flexible connection can provide a better kinetic energy absorption effect. When the original boss structural design cannot completely absorb the impact energy, the impact work in the drum is continuously absorbed through the deformation of the connecting area.

[0081] Through the above two designs, the force unloading during the drum test can effectively reduce the force on the welding area.

[0082] Before using the current collector plate provided by the present application, most of the stress generated by the movement trend transmitted from the end face 521 of the core to the current collector plate relies on the rigidity of the two welding positions of the current collector plate to resist. Therefore, a higher strength requirement is imposed on the two welding positions of the current collector plate. After using the current collector plate provided by the present application for the first current collector plate 53, part of the impact stress is resisted through the deformation of the current collector plate, reducing the requirement for welding tensile force in the structural design and ensuring the reliability of the drum battery structure of the battery cell.

[0083] 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 sequence between the two, nor can it be understood as indicating or implying relative importance. In addition, in the description of this specification, unless otherwise stated, the meaning of "a plurality" is two or more.

[0084] Any numerical value cited herein includes all values from the lower value to the upper value increasing by one unit between the lower limit value and the upper limit value, provided that there is an interval of at least two units 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 stated as ranging from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, then it is intended to illustrate that values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32, etc. are also explicitly listed in this specification. For values less than 1, a unit is appropriately considered to be 0.0001, 0.001, 0.01, 0.1. These are merely examples 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 explicitly described in this specification in a similar manner.

[0085] Unless otherwise stated, all ranges include the endpoints and all numbers between the endpoints. The "about" or "approximate" used in conjunction 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.

[0086] All articles and references disclosed, including patent applications and publications, are incorporated herein by reference for various purposes. The term "consisting essentially of" describing a combination should include the identified elements, components, parts, or steps, as well as other elements, components, parts, or steps that do not substantially affect the basic novel features of the combination. Using the terms "comprising" or "including" to describe the combination of elements, components, parts, or steps herein also contemplates embodiments consisting essentially of these elements, components, parts, or steps. By using the term "may" herein, it is intended to indicate that any attribute described as "may" be included is optional.

[0087] Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step may be separated into discrete multiple elements, components, parts, or steps. The disclosure of "a" or "an" used to describe an element, component, part, or step does not preclude the presence of other elements, components, parts, or steps.

[0088] It should be understood that the above description is illustrative and not restrictive. Many embodiments and many applications other than the examples provided will be apparent to those skilled in the art upon reading the above description. Accordingly, the scope of the present teachings should not be determined with reference to the above description, but rather should be determined with reference to the appended claims and the full scope of equivalents to which those claims are entitled. For the sake of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. Omitting any aspect of the subject matter disclosed herein from the foregoing claims is not intended to abandon such subject matter, nor should it be considered that the inventor did not consider such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A current collector plate for a cylindrical battery, which is used to be installed at the bottom of the cylindrical battery and is welded to the steel shell and the wound core of the cylindrical battery respectively; characterized in that, The current collector plate includes: A first welding portion located at the center, the first welding portion having opposite first and second planes, the first plane being used for welding with the steel shell; A second welding portion located on the periphery of the first welding portion, the second welding portion having opposite third and fourth planes, the third plane and the first plane being on the same side, the fourth plane and the second plane being on the same side, the fourth plane being used for welding with the core; the first plane protrudes from the third plane, and the fourth plane protrudes from the second plane; a hollow area is formed between the first welding portion and the second welding portion; A plurality of connecting portions disposed in the hollow area for connecting the first welding portion and the second welding portion, the total length of the connecting portions being greater than the width of the hollow area in the radial direction of the current collector plate; the connecting portions can be deformed to reduce or make the distance between the first plane and the third plane zero; The connecting portion includes a first connecting section, a second connecting section and a third connecting section, the first connecting section is connected to the first welding portion and is coplanar with the first welding portion, the third connecting section is connected to the second welding portion and is coplanar with the second welding portion, and the second connecting section is connected between the first connecting section and the third connecting section; during the assembly stage, the current collector plate has a small boss structure, and after the battery cell is encapsulated, the current collector plate forms a flat structure.

2. The current collector plate of the cylindrical battery according to claim 1, characterized in that, The total length of the connecting portions is greater than or equal to 2 times the width of the hollow area in the radial direction of the current collector plate.

3. The current collector plate of the cylindrical battery according to claim 1, characterized in that The included angle between the third connecting section and the inner diameter circle of the second welding portion is an acute angle and / or the first connecting section is tangent to the outer diameter circle of the second welding portion, 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.

4. The current collector plate of the cylindrical battery according to claim 3, characterized in that, On the first plane or the third plane, the second connecting section is collinear with the third connecting section, and the included angle between the second connecting section and the first connecting section is 90°.

5. The current collector plate of the cylindrical battery according to claim 1, 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 to 0.8 of the total length of the connecting portion.

6. The current collector plate of the 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 current collector 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.

7. The current collector plate of the cylindrical battery according to claim 1, characterized in that, The current collector plate is an integral part, and the thickness of the second welding portion is equal to the thickness of the first welding portion.

8. The current collector plate of the cylindrical battery according to claim 7, characterized in that, The central axes of the first welding portion and the second welding portion are collinear; a plurality of the connecting portions are evenly spaced in the circumferential direction; the number of the connecting portions is 2 to 4.

9. A cylindrical battery, characterized in that, Including: A steel shell; A core disposed in the steel shell; A first current collector plate, the first current collector plate being the current collector plate according to any one of claims 1-8; one side of the first current collector plate is welded to the bottom of the steel shell, and the other side is welded to the end face of the core; A second current collector plate connected to the other end face of the core; A cap disposed on the side of the second current collector plate facing away from the core.

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