Cylindrical battery and assembly method thereof

Abstract

The present invention discloses a cylindrical battery, comprising 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, 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, one end of the bare cell is provided with a first full-pole ear, the other end of the bare cell is provided with a second full-pole ear, the first full-pole ear and the cover plate are connected 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 in the direction of the first opening and forms an annular connecting surface, the annular connecting surface is bent in the axial direction of the columnar body to form a bearing plane, the second current collecting disk comprises an outer edge portion overlapped on the bearing plane and laser-welded to the bearing plane, and a protruding portion protruding in the direction of the first opening, the protruding portion is laser-welded to the second full-pole ear. The present invention uses laser penetration welding, the welding is more firm, and effectively meets the demand for high-rate charging and discharging of cylindrical power batteries.

Description

Technical Field

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

[0002] At present, lithium-ion / sodium-ion cylindrical batteries have gradually become mainstream products in the new energy industry due to their high energy density and good capacity consistency. Among them, the full-electrode / collector plate structure has been determined by more and more manufacturers as the preferred direction of cylindrical battery structure. Common questions:

[0003] 1. One end of the cylindrical power battery is usually integrated with the top cover or shell bottom, and the other end can only be welded / fixed to the bare cell and the shell bottom by resistance welding of the center hole of the bare cell. However, resistance welding is prone to 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 the requirements of high-rate charging and discharging.

[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. Summary of the invention

[0005] The object of the present invention is to provide a cylindrical battery and an assembly method thereof, so as to solve the problem of poor welding effect between a bare cell and a shell bottom in existing cylindrical batteries.

[0006] In order to achieve the above-mentioned purpose, the present invention 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 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 in the direction of the first opening and forms an annular connecting surface, the annular connecting surface is bent in the axial direction of the columnar body to form a bearing plane, the second current collecting disk comprises an outer edge portion overlapped on the bearing plane and laser-welded to the bearing plane, and a protruding portion protruding in the direction of the first opening, and the protruding portion is laser-welded to the second full-pole ear.

[0007] 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 an explosion-proof welding sheet corresponding to the annular connecting surface is stacked on the outer side of the second current collecting disk, and the outer edge of the explosion-proof welding sheet is connected to the annular connecting surface by laser seam welding.

[0008] Preferably, the connecting portion is arranged in an annular shape, and 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 of 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 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.

[0009] 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.

[0010] Preferably, an explosion-proof portion is provided on the explosion-proof welding sheet to achieve explosion-proof pressure relief.

[0011] 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.

[0012] The present invention also provides an assembly method for the above-mentioned cylindrical battery, the assembly method comprising: providing a shell, the shell comprising a columnar body, the columnar body presenting 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, the other end of the columnar body being provided with a second opening, the other end of the columnar body extending into the second opening to form a connecting portion, the connecting portion being bent in the direction of the first opening to form an annular connecting surface, the annular connecting surface being bent in the axial direction of the columnar body to form a bearing plane; providing a second current collecting plate, the second current collecting plate comprising an outer edge portion overlapping 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 with 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 the cover plate is welded to the first full-pole ear.

[0013] 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-ear, the step also includes: providing an explosion-proof welding sheet, the explosion-proof welding sheet is arranged corresponding to the annular connecting surface; stacking the explosion-proof welding sheet on the outside of the second current collecting disk; connecting the outer edge of the explosion-proof welding sheet to the annular connecting surface by laser seam welding.

[0014] Preferably, fixing the bare cell by using a clamp comprises: pressing the clamp against a first current collecting plate to fix the bare cell.

[0015] Preferably, before connecting the first full pole lug 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 arranged 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 lug; and kneading or flattening the other end of the bare battery cell to form a second full pole lug.

[0016] Compared with the prior art, the present invention sets the shell as a double-opening structure, and arranges a step-structured connecting portion, an annular connecting 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

[0017] Figure 1 This is a structural diagram of a cylindrical battery of the present invention, where the cover plate faces upward.

[0018] Figure 2 This is a structural diagram of the cylindrical battery of the present invention from another angle, where the explosion-proof welding piece faces upward.

[0019] Figure 3 It is a structural diagram of the cylindrical battery housing of the present invention.

[0020] Figure 4 for Figure 3 sectional view of .

[0021] Figure 5 It is a partial cross-sectional view of the cylindrical battery casing of the present invention.

[0022] Figure 6 It is a cross-sectional view of a cylindrical battery of the present invention.

[0023] Figure 7 for Figure 6 Enlarged view of point A in the middle.

[0024] Figure 8 This is a cross-sectional view of the cylindrical battery of the present invention after removing the explosion-proof welding sheet.

[0025] Fig. 9 It is a structural diagram of the second current collecting disk in the cylindrical battery of the present invention.

[0026] Fig.10 It is a structural diagram of the first current collecting disk in the cylindrical battery of the present invention. DETAILED DESCRIPTION

[0027] In order to explain the technical content, structural features and achieved effects of the present invention in detail, the following is a detailed description in conjunction with the implementation methods and the accompanying drawings.

[0028] like Figures 1 to 10As shown, the embodiment of the present invention 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, and the first The full pole ear is connected to the cover plate 5 through the first current collecting disk 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 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, the second current collecting disk 4 includes an outer edge portion 41 overlapped with the bearing plane 16 and laser welded to the bearing plane 16, and a protruding portion 42 protruding toward the first opening 12, and the protruding portion 42 is laser welded to the second full pole ear.

[0029] Specifically, Figures 3 to 5 As shown, the housing 1 is a double-opening structure, the first opening 12 is provided at the upper end of the cylindrical battery 10, the second opening 13 is provided at the lower end of the cylindrical battery 10, the bearing plane 16 is a circular ring surface, and the connecting portion 14, the annular connecting surface 15 and the bearing plane 16 form a step structure, as shown in FIG. Figure 6 and Figure 8 As shown, the columnar body 11 and the cover plate 5 can be connected in a conventional manner, such as by rolling groove 17 or laser welding. Fig.10 As shown, the structure of the first collector plate 3 can be a conventional structure, including a collector plate body 31 and a bending portion 32 connected to the collector plate body 31. The connection method between the first collector plate 3 and the first full-pole ear and the cover plate 5 can also adopt a conventional connection method. The present invention sets the shell 1 as a double-opening structure, and sets a step-structured connection portion 14, an annular connection surface 15 and a bearing plane 16 at the second opening 13. Since the bearing plane 16 has a certain area, the outer edge 41 of the second collector plate 4 can be welded to the bearing plane 16 by laser penetration welding, and the raised portion 42 of the second collector plate 4 can be welded to the second full-pole ear by laser penetration welding, 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.

[0030] In the embodiment of the present invention, Figure 5 and Figure 7As shown, the thickness of the second current 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 outer side of the second current collecting disc 4, and 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, Figure 7 As shown, the explosion-proof portion 61 is arranged in the middle of the explosion-proof welding piece 6, and the diameter of the explosion-proof welding piece 6 is set corresponding to the inner diameter of the annular connecting surface 15, and is 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. The setting of the annular connecting surface 15 allows the explosion-proof welding piece 6 to 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.

[0031] In the embodiment of the present invention, Figure 5 As shown, the connecting portion 14 is arranged in an annular shape, a 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, a 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, a 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, and a 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 change accordingly, and can be designed according to actual needs.

[0032] In the embodiment of the present invention, 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 the same as 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.

[0033] In the embodiment of the present invention, the second current collecting plate 4 is plate-shaped, a first through hole 43 is opened in the middle of the second current collecting plate 4, and the protrusions 42 are multiple and fan-shaped, and the multiple protrusions 42 are evenly distributed on the second current collecting plate 4. Fig. 9 As shown, there are three protrusions 42 , and the three protrusions 42 are evenly distributed on the second collecting plate 4 .

[0034] like Figures 1 to 10 As shown, the embodiment of the present invention also provides an assembly method of a cylindrical battery 10, the assembly method comprising:

[0035] S1. Provide a shell 1, which 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 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 to form 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. Specifically, refer to Figures 3 to 5 shown.

[0036] S2. Provide a second current collecting disc 4, the second current collecting disc 4 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, overlap the outer edge portion 41 of the second current collecting disc 4 on the bearing plane 16 of the shell 1, and perform laser penetration welding on the outer edge portion 41 and the bearing plane 16; specifically, refer to Figure 3 , Figure 4 , Figure 8 as well as Fig. 9 As shown, the second current collecting plate 4 matched with the bearing plane 16 and the annular connecting surface 15 is first overlapped on the bearing plane 16 and the outer edge 41 of the first current collecting plate 3 is welded to the bearing plane 16 by laser penetration welding.

[0037] S3, provide a bare cell 2, one end of the bare cell 2 is provided with a first full-pole ear, the other end of the bare cell 2 is provided with a second full-pole ear, and the first full-pole ear of the bare cell 2 is connected to the first current collecting plate 3; specifically, refer to Figure 8 and Fig.10 As shown, the first current collecting plate 3 includes a current collecting plate body 31 and a bending portion 32 connected to the current collecting plate body 31 , and the first full pole ear of the bare cell 2 is welded to the current collecting plate body 31 , and the specific connection process can adopt a conventional welding process.

[0038] S4, install the bare cell 2 connected with the first current collecting disk 3 in the housing 1, and fix the bare cell 2 with a clamp so that the second full pole ear of the bare cell 2 abuts against the raised portion 42 of the second current collecting disk 4, and weld the second full pole ear to the raised portion 42 of the second current collecting disk 4 by laser penetration welding; specifically, refer to Figure 8 and Fig. 9 As shown, since the protrusion 42 protrudes toward the position of the bare battery cell 2, the bare battery cell 2 can contact the protrusion 42 to facilitate laser penetration welding.

[0039] S5, providing a cover plate 5, the cover plate 5 closes the first opening 12 and welds the cover plate 5 to the first full tab. Figure 1 and Figure 8 As shown, 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 pole ear, the columnar body 11 forms a sealing connection with the cover plate 5 by forming a rolling groove 17.

[0040] In the embodiment of the present invention, a shell 1 with a double-opening structure is designed, and a connecting portion 14 with a step structure, an annular connecting surface 15 and a bearing plane 16 are arranged at the second opening 13. Since the bearing plane 16 has a certain area, the outer edge portion 41 of the second current collecting plate 4 can be welded to the bearing plane 16 by laser penetration welding, and the raised portion 42 of the second current collecting plate 4 can be welded to the second full pole ear by laser penetration welding, replacing the existing resistance welding method of the center hole of the bare battery cell. The welding is more firm, which effectively meets the demand for high-rate charging and discharging of cylindrical power batteries.

[0041] It should be noted that the order of step S2 and step S3 can be swapped, and step S3 can be executed first, and then step S2.

[0042] In the embodiment of the present invention, step S3, before connecting the first full tab of the bare cell 2 to the first current collecting plate 3, further includes:

[0043] 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;

[0044] S032, flattening or patting one end of the bare battery cell 2 to form a first full pole ear; specifically, the first full pole ear can be the pole ear of the positive electrode sheet or the pole ear of the negative electrode sheet, for example, the first full pole ear is the pole ear corresponding to the positive electrode sheet.

[0045] S033, flatten or pat the other end of the bare cell 2 to form a second full-pole tab. Specifically, when the first full-pole tab is the tab corresponding to the positive electrode sheet, the second full-pole tab is the tab corresponding to the negative electrode sheet.

[0046] In the embodiment of the present invention, the thickness of the second current 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-electrode tab, further includes:

[0047] S61 . Provide an explosion-proof welding piece 6 , which is disposed corresponding to the annular connecting surface 15 .

[0048] S62, stacking the explosion-proof welding sheet 6 on the outer side of the second current collecting plate 4; specifically, as Figure 7 As shown, the explosion-proof welding piece 6 is embedded and installed in the annular connecting surface 15 and is arranged above the second collecting plate 4.

[0049] S63, connecting the outer edge of the explosion-proof welding piece 6 and the annular connecting surface 15 by laser seam welding. Specifically, connecting the outer edge of the explosion-proof welding piece 6 and the annular connecting surface 15 by laser seam welding. The explosion-proof welding piece 6 is also used to close the second opening 13.

[0050] In the embodiment of the present invention, in step S4, fixing the bare battery cell 2 with a clamp includes:

[0051] S41, pressing 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-polarity tab of the bare cell 2.

[0052] In the embodiment of the present invention, the cover plate 5 is provided with a liquid injection hole 51, which 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 step further includes:

[0053] S71, injecting liquid into the bare battery cell 2 through the injection hole 51;

[0054] S72, after the injection is completed, the injection hole 51 is sealed by a steel ball or UV glue or a sealing nail.

[0055] The present invention sets the shell 1 as a double-opening structure, and sets a step-structured connection portion 14, an annular connection surface 15 and a bearing plane 16 at the second opening 13. Since the bearing plane 16 has a certain area, the outer edge 41 of the second collector 4 can be welded to the bearing plane 16 by laser penetration welding, and the raised portion 42 of the second collector 4 can be welded to the second full-pole ear by laser penetration welding, 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. At the same time, the annular connection surface 15 is set so that 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. 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 during loading of large batteries, it is not easy to fail / leakage and other problems, and the reliability of the battery structure is higher; the second current collecting disk 4 is welded on the bearing plane 16 at the bottom of the shell 1 to ensure a larger welding flow area, and the connecting part 14, the annular connecting surface 15 and the bearing plane 16 of the shell 1 can directly perform strong radial limiting on the second current collecting disk 4 to reduce radial impact caused by vibration; when the bare battery cell 2 is impacted axially by the vibration caused by loading of the cylindrical battery, the explosion-proof valve plate 6 at the bottom can avoid direct impact, that is, the second current collecting disk 4 plays a buffering role to extend the battery life.

[0056] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

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 in the direction of the first opening to form an annular connecting surface, the annular connecting surface is bent in the axial direction of the columnar body to form a bearing plane, the second current collecting plate includes an outer edge portion overlapped on the bearing plane and connected to the bearing plane by laser penetration welding, and a protruding portion protruding in the direction of the first opening, the protruding portion is connected to the second full-pole ear by laser welding; 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 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.

2. The cylindrical battery according to claim 1, characterized in that: The connecting portion is arranged in a ring 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 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.

3. The cylindrical battery according to claim 1, 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.

4. The cylindrical battery according to claim 1, characterized in that: An explosion-proof portion is arranged on the explosion-proof welding piece to achieve explosion-proof pressure relief.

5. The cylindrical battery according to claim 4, 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.

6. A method for assembling a cylindrical battery as claimed in any one of claims 1 to 5, 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 in the direction of the first opening to form an annular connecting surface, the annular connecting surface is bent in the axial direction of the columnar body to form a bearing plane, and the height of the annular connecting surface in the axial direction of the columnar body is greater than or equal to 0.25 mm; 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; Providing a cover plate, the cover plate closing the first opening and welding the cover plate to the first full tab; Wherein, 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.

7. The method for assembling a cylindrical battery according to claim 6, 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.

8. The method for assembling a cylindrical battery according to claim 6, 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.

Images