Cylindrical battery and assembly method therefor

Abstract

Disclosed is a cylindrical battery, comprising a housing, bare cells, a first current collector, a second current collector, and a cover plate, wherein the housing comprises a columnar main body, with a first opening being provided in one end of the columnar main body and a second opening being provided in the other end of the columnar main body; a first full-tab is provided at one end of each of the bare cells and a second full-tab is provided at the other end of the bare cell, the first full-tab being connected to the cover plate by means of the first current collector; the other end of the columnar main body extends into the second opening to form a connecting portion, the connecting portion bends toward the first opening to form an annular connecting surface, and the annular connecting surface bends toward an axis of the columnar main body to form a bearing surface; and the second current collector comprises an outer edge which is in lap joint with the bearing surface and which is connected to the bearing surface by means of laser welding, and a protrusion protruding toward the first opening, the protrusion being connected to the second full-tab by means of laser welding. The present application uses laser penetration welding, which provides firm welding and effectively meets the requirements of high charging and discharging rates of cylindrical power batteries.

Description

Cylindrical battery and assembly method thereof Technical Field

[0001] The present application relates to the field of batteries, and in particular to a cylindrical battery and an assembly method thereof. Background Art

[0002] Currently, lithium-ion / sodium-ion cylindrical batteries are becoming mainstream products in the new energy industry due to their high energy density and good capacity consistency. Among them, the full-tab / collector plate structure is being selected by more and more manufacturers as the preferred direction for cylindrical battery structure. Common questions:

[0003] 1. Cylindrical power batteries usually have a top cover or shell bottom integrated at one end of the pole, and the other end can only be welded / fixed to the shell bottom by resistance welding through the center hole of the bare cell. However, resistance welding is prone to problems such as cold welding or the normal welding position may fall off during vehicle vibration. In addition, the small welding area of ​​resistance welding leads to poor current capacity and cannot meet high-rate charge and discharge requirements.

[0004] 2. It is difficult to implement explosion-proof valve pressure relief for cylindrical power batteries because one end of the pole is too small to implement an explosion-proof valve, and the middle of the other end is fixed to the bottom of the shell by resistance welding, which also cannot be implemented. Therefore, it will bring safety problems.

[0005] Application Contents

[0006] The purpose of the present application is to provide a cylindrical battery and an assembly method thereof to solve the problem of poor welding effect between the bare cell and the shell bottom in existing cylindrical batteries.

[0007] In order to achieve the above-mentioned purpose, the present application provides a cylindrical battery, comprising a shell, a bare cell, a first current collecting disk, a second current collecting disk and a cover plate, the shell comprising a columnar body, the columnar body being a hollow structure and both ends of the columnar body being open structures, one end of the columnar body being provided with a first opening, and the other end of the columnar body being provided with a second opening, the bare cell being arranged in the shell, and one end of the bare cell being provided with a first full-pole ear, and the other end of the bare cell being provided with a second full-pole ear, the cover plate closing the first opening, and the first full-pole ear and the cover plate being connected by the first current collecting disk; the other end of the columnar body extends into the second opening to form a connecting portion, the connecting portion is bent toward the first opening direction and forms an annular connecting surface, the annular connecting surface is bent toward the axial direction of the columnar body to form a bearing plane, the second current collecting disk comprises an outer edge portion overlapping the bearing plane and laser-welded to the bearing plane, and a protruding portion protruding toward the first opening direction, and the protruding portion is laser-welded to the second full-pole ear.

[0008] Preferably, the thickness of the second collecting disc in the axial direction of the columnar body is smaller than the height of the annular connecting surface in the axial direction of the columnar body, and an explosion-proof welding piece corresponding to the annular connecting surface is stacked on the outside of the second collecting disc, and the outer edge of the explosion-proof welding piece is connected to the annular connecting surface by laser seam welding.

[0009] Preferably, the connecting portion is arranged in an annular shape, the first width of the connecting portion in the axial direction toward the columnar body is greater than or equal to 1.5 mm, the height of the annular connecting surface in the axial direction of the columnar body is greater than or equal to 0.25 mm, the second width of the bearing plane in the axial direction toward the columnar body is greater than or equal to 2 mm, and the sum of the first width of the connecting portion in the axial direction toward the columnar body and the second width of the bearing plane in the axial direction toward the columnar body is less than the radius of the columnar body.

[0010] Preferably, the sum of the thickness of the outer edge of the second collecting plate in the axial direction of the columnar body and the thickness of the explosion-proof welding piece in the axial direction of the columnar body is equal to the height of the annular connecting surface in the axial direction of the columnar body.

[0011] Preferably, an explosion-proof portion is provided on the explosion-proof welding piece to achieve explosion-proof pressure relief.

[0012] Preferably, the second current collecting disk is in a plate shape, a first through hole is opened in the middle of the second current collecting disk, the protrusions are multiple and arranged in a fan shape, and the multiple protrusions are evenly distributed on the second current collecting disk.

[0013] The present application also provides an assembly method for the above-mentioned cylindrical battery, which comprises: providing a shell, wherein the shell comprises a columnar body, the columnar body is a hollow structure and both ends of the columnar body are open structures, one end of the columnar body is provided with a first opening, the other end of the columnar body is provided with a second opening, the other end of the columnar body extends into the second opening to form a connecting portion, the connecting portion is bent in the direction of the first opening to form an annular connecting surface, and the annular connecting surface is bent in the axial direction of the columnar body to form a bearing plane; providing a second collecting plate, the second collecting plate comprises an outer edge portion overlapped with the bearing plane and laser welded to the bearing plane, and an outer edge portion extending in the direction of the first opening The raised protrusion overlaps the outer edge of the second current collecting disk on the bearing plane and performs laser penetration welding on the outer edge and the bearing plane; provides a bare battery cell, one end of the bare battery cell is provided with a first full-pole ear, and the other end of the bare battery cell is provided with a second full-pole ear, and the first full-pole ear of the bare battery cell is connected to the first current collecting disk; the bare battery cell connected to the first current collecting disk is installed in the shell, and the bare battery cell is fixed with a clamp so that the second full-pole ear of the bare battery cell abuts against the raised portion of the second current collecting disk, and the second full-pole ear is welded to the raised portion of the second current collecting disk by laser penetration welding; provides a cover plate, the cover plate closes the first opening and welds the cover plate to the first full-pole ear.

[0014] Preferably, the thickness of the second current collecting disk in the axial direction of the columnar body is smaller than the height of the annular connecting surface in the axial direction of the columnar body, and after the step of welding the cover plate to the first full-electrode tab, the step also includes: providing an explosion-proof welding sheet, which is arranged corresponding to the annular connecting surface; stacking the explosion-proof welding sheet on the outside of the second current collecting disk; and connecting the outer edge of the explosion-proof welding sheet to the annular connecting surface by laser seam welding.

[0015] Preferably, fixing the bare cell by using a clamp comprises: pressing the clamp against the first current collecting plate to fix the bare cell.

[0016] Preferably, before connecting the first full pole tab of the bare battery cell to the first current collecting disk, the process also includes: winding the positive electrode sheet, the negative electrode sheet and the isolation film provided between the positive electrode sheet and the negative electrode sheet to form a bare battery cell; kneading or flattening one end of the bare battery cell to form a first full pole tab; and kneading or flattening the other end of the bare battery cell to form a second full pole tab.

[0017] Compared with the prior art, the present application sets the shell into a double-opening structure, and arranges a step-structured connection portion, an annular connection surface and a bearing plane at the second opening. Since the bearing plane has a certain area, laser penetration welding can be used to weld the outer edge of the second current collecting plate to the bearing plane, and laser penetration welding can be used to weld the raised portion of the second current collecting plate to the second full pole ear, replacing the existing resistance welding method of the center hole of the bare battery cell. The welding is more firm and effectively meets the needs of high-rate charging and discharging of cylindrical power batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1 is a structural diagram of a cylindrical battery of the present application, in which the cover plate faces upward.

[0019] FIG2 is a structural diagram of the cylindrical battery of the present application from another angle, in which the explosion-proof welding piece faces upward.

[0020] FIG3 is a structural diagram of the cylindrical battery housing of the present application.

[0021] FIG4 is a cross-sectional view of FIG3 .

[0022] FIG5 is a partial cross-sectional view of the cylindrical battery housing of the present application.

[0023] FIG6 is a cross-sectional view of the cylindrical battery of the present application.

[0024] FIG7 is an enlarged view of point A in FIG6 .

[0025] FIG8 is a cross-sectional view of the cylindrical battery of the present application after removing the explosion-proof welding piece.

[0026] FIG9 is a structural diagram of the second current collecting plate in the cylindrical battery of the present application.

[0027] FIG10 is a structural diagram of the first current collecting plate in the cylindrical battery of the present application. DETAILED DESCRIPTION

[0028] In order to explain the technical content, structural features and achieved effects of this application in detail, the following is a detailed description in conjunction with the implementation methods and the accompanying drawings.

[0029] As shown in Figures 1 to 10, the embodiment of the present application discloses a cylindrical battery, including a shell 1, a bare cell 2, a first current collecting plate 3, a second current collecting plate 4 and a cover plate 5. The shell 1 includes a columnar body 11, the columnar body 11 is a hollow structure and both ends of the columnar body 11 are open structures. One end of the columnar body 11 is provided with a first opening 12, and the other end of the columnar body 11 is provided with a second opening 13. The bare cell 2 is arranged in the shell 1, and one end of the bare cell 2 is provided with a first full-pole ear, and the other end of the bare cell 2 is provided with a second full-pole ear. The cover plate 5 closes the first opening 12. 2. The first full-pole tab is connected to the cover plate 5 via the first current collecting disc 3. The other end of the columnar body 11 extends into the second opening 13 to form a connecting portion 14. The connecting portion 14 is bent toward the first opening 12 to form an annular connecting surface 15. The annular connecting surface 15 is bent toward the axis of the columnar body 11 to form a bearing plane 16. The second current collecting disc 4 includes an outer edge portion 41 that overlaps the bearing plane 16 and is laser-welded to the bearing plane 16, and a protrusion 42 that protrudes toward the first opening 12. The protrusion 42 is laser-welded to the second full-pole tab.

[0030] Specifically, as shown in Figures 3 to 5, the shell 1 has a double-opening structure, the first opening 12 is provided at the upper end of the cylindrical battery 10, and the second opening 13 is provided at the lower end of the cylindrical battery 10. The bearing plane 16 is a circular surface, and the connecting portion 14, the annular connecting surface 15 and the bearing plane 16 form a step structure. As shown in Figures 6 and 8, a conventional connection method can be adopted between the columnar body 11 and the cover plate 5, such as sealing by rolling groove 17 or laser welding; as shown in Figure 10, the structure of the first collecting plate 3 can be a conventional structure, including a collecting plate body 31 and a bending portion 32 connected to the collecting plate body 31. The connection method between the first collecting plate 3 and the first full pole ear and the cover plate 5 can also adopt a conventional connection method. In the present application, the shell 1 is set as a double-opening structure, and a step-structured connecting portion 14, an annular connecting surface 15 and a bearing plane 16 are provided at the second opening 13. Since the bearing plane 16 has a certain area, laser penetration welding can be used to weld the outer edge 41 of the second current collecting disc 4 to the bearing plane 16, and laser penetration welding can be used to weld the raised portion 42 of the second current collecting disc 4 to the second full-pole ear, replacing the existing resistance welding method of the center hole of the bare battery cell. The welding is more firm and effectively meets the requirements of high-rate charging and discharging of cylindrical power batteries.

[0031] In the embodiment of the present application, as shown in Figures 5 and 7, the thickness of the second collecting disc 4 in the axial direction of the columnar body 11 is less than the height c of the annular connecting surface 15 in the axial direction of the columnar body 11, and an explosion-proof welding piece 6 corresponding to the annular connecting surface 15 is stacked on the outside of the second collecting disc 4. The outer edge of the explosion-proof welding piece 6 is connected to the annular connecting surface 15 by laser seam welding. Specifically, the explosion-proof welding piece 6 is circular, and an explosion-proof portion 61 is provided on the explosion-proof welding piece 6 to achieve explosion-proof pressure relief. For example, as shown in Figure 7, the explosion-proof portion 61 is provided in the middle of the explosion-proof welding piece 6, and the diameter of the explosion-proof welding piece 6 corresponds to the inner diameter of the annular connecting surface 15, preferably slightly smaller than the inner diameter of the annular connecting surface 15 so as to be embedded in the annular connecting surface 15, and the explosion-proof welding piece 6 and the annular connecting surface 15 can be connected by laser seam welding along the connecting gap 62 between the explosion-proof welding piece 6 and the annular connecting surface 15. By setting the annular connecting surface 15, the explosion-proof welding piece 6 can be set at the bottom of the cylindrical battery 10, which can effectively improve the safety of the cylindrical power battery, and the design is very clever.

[0032] In the embodiment of the present application, as shown in Figure 5, the connecting portion 14 is arranged in an annular shape, and the first width a of the connecting portion 14 in the axial direction toward the columnar body 11 is greater than or equal to 1.5 mm, the height c of the annular connecting surface 15 in the axial direction toward the columnar body 11 is greater than or equal to 0.25 mm, and the second width b of the bearing plane 16 in the axial direction toward the columnar body 11 is greater than or equal to 2 mm. The sum of the first width a of the connecting portion 14 in the axial direction toward the columnar body 11 and the second width b of the bearing plane 16 in the axial direction toward the columnar body 11 is less than the radius of the columnar body 11. Specifically, the diameter of the cylindrical battery 10 is greater than 18 mm and the height is greater than 70 mm. The first width a of the connecting portion 14 in the axial direction toward the columnar body 11 is preferably greater than or equal to 1.5 mm and less than or equal to 5 mm, the height c of the annular connecting surface 15 in the axial direction of the columnar body 11 is preferably greater than or equal to 0.25 mm and less than or equal to 1.2 mm, and the second width b of the bearing plane 16 in the axial direction toward the columnar body 11 is preferably greater than or equal to 2 mm and less than or equal to 4 mm. Of course, for cylindrical batteries 10 of different sizes, the sizes of the connecting portion 14, the annular connecting surface 15 and the bearing plane 16 may vary accordingly, and can be designed according to actual needs.

[0033] In the embodiment of the present application, the sum of the thickness of the outer edge portion 41 of the second current collecting plate 4 in the axial direction of the columnar body 11 and the thickness of the explosion-proof welding piece 6 in the axial direction of the columnar body 11 is equal to the height c of the annular connecting surface 15 in the axial direction of the columnar body 11. Specifically, the outermost plane of the explosion-proof welding piece 6 is preferably flush with the outermost plane of the connecting portion 14 to stably support the cylindrical battery 10.

[0034] In the embodiment of the present application, the second collecting disc 4 is plate-shaped, a first through hole 43 is opened in the middle of the second collecting disc 4, there are multiple raised portions 42 and they are arranged in a fan shape, and the multiple raised portions 42 are evenly distributed on the second collecting disc 4. As shown in Figure 9, there are specifically three raised portions 42, and the three raised portions 42 are evenly distributed on the second collecting disc 4.

[0035] As shown in FIG. 1 to FIG. 10 , the embodiment of the present application further provides an assembly method of a cylindrical battery 10 , the assembly method comprising:

[0036] S1. Provide a shell 1, which includes a columnar body 11. The columnar body 11 has a hollow structure and both ends of the columnar body 11 are open structures. One end of the columnar body is provided with a first opening 12, and the other end of the columnar body 11 is provided with a second opening 13. The other end of the columnar body 11 extends into the second opening 13 to form a connecting portion 14. The connecting portion 14 is bent toward the first opening 12 and forms an annular connecting surface 15. The annular connecting surface 15 is bent toward the axial direction of the columnar body 11 to form a bearing plane 16. For details, refer to Figures 3 to 5.

[0037] S2. Provide a second collecting disc 4, which includes an outer edge portion 41 overlapped on the bearing plane 16 and laser-welded to the bearing plane 16, and a protrusion 42 protruding toward the first opening 12. The outer edge portion 41 of the second collecting disc 4 is overlapped on the bearing plane 16 of the shell 1 and the outer edge portion 41 and the bearing plane 16 are laser-penetrated and welded. Specifically, referring to Figures 3, 4, 8 and 9, the second collecting disc 4 that cooperates with the bearing plane 16 and the annular connecting surface 15 is first overlapped on the bearing plane 16 and the outer edge portion 41 of the first collecting disc 3 is welded to the bearing plane 16 by laser-penetration welding.

[0038] S3. Provide a bare battery cell 2, wherein a first full-pole tab is provided at one end of the bare battery cell 2 and a second full-pole tab is provided at the other end of the bare battery cell 2, and the first full-pole tab of the bare battery cell 2 is connected to the first collecting plate 3; specifically, referring to Figures 8 and 10, the first collecting plate 3 includes a collecting plate main body 31 and a bending portion 32 connected to the collecting plate main body 31, and the first full-pole tab of the bare battery cell 2 is welded to the collecting plate main body 31. The specific connection process can adopt a conventional welding process.

[0039] S4. Install the bare cell 2 connected to the first current collecting disk 3 in the shell 1, and fix the bare cell 2 with a clamp so that the second full-pole tab of the bare cell 2 abuts against the raised portion 42 of the second current collecting disk 4, and weld the second full-pole tab to the raised portion 42 of the second current collecting disk 4 by laser penetration welding; specifically, referring to Figures 8 and 9, since the raised portion 42 protrudes toward the position of the bare cell 2, the bare cell 2 can contact the raised portion 42 to facilitate laser penetration welding.

[0040] S5. Provide a cover plate 5, which closes the first opening 12 and is welded to the first full tab. Specifically, as shown in Figures 1 and 8, the cover plate 5 closes the first opening 12 and is connected to the columnar body 11. The end of the columnar body 11 connected to the cover plate 5 is cylindrical when not connected to the cover plate 5. After the cover plate 5 is embedded in the columnar body 11 and welded to the bent portion 32 of the first full tab, the columnar body 11 is sealed with the cover plate 5 by forming a rolling groove 17.

[0041] In the embodiment of the present application, a shell 1 with a double-opening structure is designed, and a step-structured connecting portion 14, an annular connecting surface 15 and a bearing plane 16 are provided at the second opening 13. Since the bearing plane 16 has a certain area, laser penetration welding can be used to weld the outer edge 41 of the second current collecting disc 4 to the bearing plane 16, and laser penetration welding can be used to weld the raised portion 42 of the second current collecting disc 4 to the second full-pole tab, replacing the existing resistance welding method of the center hole of the bare battery cell. The welding is more firm and effectively meets the requirements of high-rate charging and discharging of cylindrical power batteries.

[0042] It should be noted that the order of step S2 and step S3 can be swapped, and step S3 can be performed first, and then step S2.

[0043] In the embodiment of the present application, step S3, before connecting the first full tab of the bare cell 2 to the first current collecting plate 3, further includes:

[0044] S031, winding the positive electrode sheet, the negative electrode sheet, and the separator disposed between the positive electrode sheet and the negative electrode sheet to form a bare battery cell 2;

[0045] S032, flattening or patting one end of the bare battery cell 2 to form a first full-pole tab; specifically, the first full-pole tab can be the tab of the positive electrode sheet or the tab of the negative electrode sheet, for example, the first full-pole tab is the tab corresponding to the positive electrode sheet.

[0046] S033, flattening or tamping the other end of the bare cell 2 to form a second full tab. Specifically, when the first full tab is the tab corresponding to the positive electrode sheet, the second full tab is the tab corresponding to the negative electrode sheet.

[0047] In the embodiment of the present application, the thickness of the second collecting plate 4 in the axial direction of the columnar body 11 is less than the height of the annular connecting surface 15 in the axial direction of the columnar body 11. Step S5, after welding the cover plate 5 to the first full tab, further includes:

[0048] S61 , providing an explosion-proof welding piece 6 , which is disposed corresponding to the annular connecting surface 15 .

[0049] S62 , stacking the explosion-proof welding piece 6 on the outside of the second current collecting plate 4 ; specifically, as shown in FIG. 7 , the explosion-proof welding piece 6 is embedded and installed in the annular connecting surface 15 and is arranged above the second current collecting plate 4 .

[0050] S63, connecting the outer edge of the explosion-proof welding piece 6 to the annular connecting surface 15 by laser seam welding. Specifically, connecting the outer edge of the explosion-proof welding piece 6 to the annular connecting surface 15 by laser seam welding. The explosion-proof welding piece 6 is also used to close the second opening 13.

[0051] In the embodiment of the present application, in step S4, fixing the bare battery cell 2 with a clamp includes:

[0052] S41: Press the clamp against the first current collecting plate 3 to fix the bare cell 2. Since the bare cell 2 is first connected to the first current collecting plate 3, pressing the clamp against the first current collecting plate 3 can also prevent the clamp from damaging the first full tab of the bare cell 2.

[0053] In the embodiment of the present application, a liquid injection hole 51 is provided on the cover plate 5, and the liquid injection hole is connected to the middle hole of the bare battery cell 2. After the step S63 of connecting the outer edge of the explosion-proof welding piece 6 and the annular connecting surface 15 by laser seam welding, the following steps are also included:

[0054] S71, injecting liquid into the bare battery cell 2 through the liquid injection hole 51;

[0055] S72, after the liquid injection is completed, the liquid injection hole 51 is sealed by a steel ball, UV glue or sealing nail.

[0056] This application provides a dual-opening structure for the housing 1, and provides a stepped connection portion 14, an annular connection surface 15, and a bearing surface 16 at the second opening 13. Since the bearing surface 16 has a certain area, laser penetration welding can be used to weld the outer edge 41 of the second current collecting plate 4 to the bearing surface 16, and the raised portion 42 of the second current collecting plate 4 to the second full-electrode tab. This replaces the existing resistance welding method of the center hole of the bare battery cell, resulting in a more secure weld and effectively meeting the high-rate charge and discharge requirements of cylindrical power batteries. Furthermore, the provision of the annular connection surface 15 allows for the installation of an explosion-proof welding piece 6 at the bottom of the cylindrical battery 10, effectively improving the safety of the cylindrical power battery. This design is very ingenious. At the same time, the bottom of the shell 1 has an annular plane feature of an integrally formed connecting part 14, an annular connecting surface 15 and a bearing plane 16. The thickness / strength of the bending part connected to the shell 1 is much greater than that of laser welding. When facing the impact caused by long-term vibration when loading large batteries, it is not easy to have problems such as failure / leakage, and the reliability of the battery structure is higher; the bearing plane 16 at the bottom of the shell 1 is welded to the second collecting disk 4, which can ensure a larger welding flow area, and the connecting part 14, annular connecting surface 15 and bearing plane 16 of the shell 1 can directly perform strong radial limitation on the second collecting disk 4 to reduce radial impact caused by vibration; when the bare battery cell 2 is axially impacted by the vibration of the cylindrical battery loading, the explosion-proof valve plate 6 at the bottom can avoid direct impact, that is, the second collecting disk 4 plays a buffering role, thereby extending the battery life.

[0057] The above disclosure is only a preferred example of the present application, and certainly cannot be used to limit the scope of rights of the present application. Therefore, equivalent changes made according to the scope of the patent application of the present application still fall within the scope covered by the present application.

Claims

1. A cylindrical battery, characterized in that: The invention comprises a shell, a bare cell, a first current collecting disk, a second current collecting disk and a cover plate, wherein the shell comprises a columnar body, the columnar body is a hollow structure and both ends of the columnar body are open structures, one end of the columnar body is provided with a first opening, and the other end of the columnar body is provided with a second opening, the bare cell is arranged in the shell, and one end of the bare cell is provided with a first full-pole ear, and the other end of the bare cell is provided with a second full-pole ear, the cover plate closes the first opening, and the first full-pole ear is connected to the cover plate through the first current collecting disk; The other end of the columnar body extends into the second opening to form a connecting portion, the connecting portion is bent toward the first opening direction to form an annular connecting surface, the annular connecting surface is bent toward the axial direction of the columnar body to form a bearing plane, the second current collecting plate includes an outer edge portion overlapping the bearing plane and laser-welded to the bearing plane, and a protruding portion protruding toward the first opening direction, the protruding portion is laser-welded to the second full-pole ear.

2. The cylindrical battery according to claim 1, characterized in that: The thickness of the second current collecting disk in the axial direction of the columnar body is smaller than the height of the annular connecting surface in the axial direction of the columnar body. An explosion-proof welding piece corresponding to the annular connecting surface is also stacked on the outer side of the second current collecting disk, and the outer edge of the explosion-proof welding piece is connected to the annular connecting surface by laser seam welding.

3. The cylindrical battery according to claim 2, characterized in that: The connecting portion is arranged in an annular shape, a first width of the connecting portion in the axial direction toward the columnar body is greater than or equal to 1.5 mm, a height of the annular connecting surface in the axial direction toward the columnar body is greater than or equal to 0.25 mm, a second width of the bearing plane in the axial direction toward the columnar body is greater than or equal to 2 mm, and a sum of the first width of the connecting portion in the axial direction toward the columnar body and the second width of the bearing plane in the axial direction toward the columnar body is less than the radius of the columnar body.

4. The cylindrical battery according to claim 3, characterized in that: The sum of the thickness of the outer edge of the second current collecting plate in the axial direction of the columnar body and the thickness of the explosion-proof welding piece in the axial direction of the columnar body is equal to the height of the annular connecting surface in the axial direction of the columnar body.

5. The cylindrical battery according to claim 2, characterized in that: An explosion-proof portion is arranged on the explosion-proof welding piece to achieve explosion-proof pressure relief.

6. The cylindrical battery according to claim 5, characterized in that: The second current collecting disk is in a plate shape, a first through hole is opened in the middle of the second current collecting disk, the protrusions are multiple and arranged in a fan shape, and the multiple protrusions are evenly distributed on the second current collecting disk.

7. A method for assembling a cylindrical battery as claimed in any one of claims 1 to 6, characterized in that: The assembly method comprises: A shell is provided, the shell comprising a columnar body, the columnar body is a hollow structure and both ends of the columnar body are open structures, one end of the columnar body is provided with a first opening, the other end of the columnar body is provided with a second opening, the other end of the columnar body extends into the second opening to form a connecting portion, the connecting portion is bent toward the first opening direction to form an annular connecting surface, and the annular connecting surface is bent toward the axial direction of the columnar body to form a bearing plane; Providing a second current collecting disc, the second current collecting disc comprising an outer edge portion overlapped on the bearing plane and laser-welded to the bearing plane, and a protruding portion protruding toward the first opening, overlapping the outer edge portion of the second current collecting disc on the bearing plane and laser-penetrating-welding the outer edge portion to the bearing plane; A bare battery cell is provided, wherein one end of the bare battery cell is provided with a first full-polarity tab, and the other end of the bare battery cell is provided with a second full-polarity tab, and the first full-polarity tab of the bare battery cell is connected to a first current collecting disk; Installing the bare cell connected with the first current collector in the housing, fixing the bare cell with a clamp so that the second full pole tab of the bare cell abuts against the raised portion of the second current collector, and welding the second full pole tab to the raised portion of the second current collector by laser penetration welding; A cover plate is provided, the cover plate closes the first opening and the cover plate is welded to the first full tab.

8. The method for assembling a cylindrical battery according to claim 7, characterized in that: The thickness of the second current collecting plate in the axial direction of the columnar body is smaller than the height of the annular connecting surface in the axial direction of the columnar body, and after the step of welding the cover plate to the first full-electrode tab, the step further includes: Providing an explosion-proof welding piece, wherein the explosion-proof welding piece is arranged corresponding to the annular connecting surface; Stacking the explosion-proof welding sheet on the outer side of the second current collecting plate; The outer edge of the explosion-proof welding piece is connected to the annular connecting surface by laser seam welding.

9. The method for assembling a cylindrical battery according to claim 7, characterized in that: The method of fixing the bare battery core by a clamp comprises: The clamp is pressed against the first current collecting plate to fix the bare battery cell.

10. The method for assembling a cylindrical battery according to claim 7, characterized in that: Before connecting the first full-electrode tab of the bare cell to the first current collecting plate, the method further includes: Winding a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet to form a bare battery cell; One end of the bare battery cell is flattened or patted to form a first full-polarity ear; The other end of the bare battery cell is flattened or patted to form a second full-pole ear.

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