Secondary battery and battery pack

Abstract

Disclosed are a secondary battery and a battery pack. A through hole is formed in a pole, a sealing piece is disposed in the through hole, a sealing member has a first end connected to a first current collecting disc by means of welding and a second end connected to the pole by means of welding, the pole is electrically connected to the first current collecting disc by means of the sealing piece, and the pole is not welded to the first current collecting disc, so that the welding positions of the sealing member and the current collecting disc fit more tightly without any gap, thereby ensuring the welding effect while ensuring the sealing effect.

Description

Secondary batteries and battery packs

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on August 25, 2023, with application number 202322303114.0 and application name “Secondary Batteries and Battery Packs”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a secondary battery and a battery pack. Background Art

[0003] The pole terminal and the current collecting plate in the existing secondary battery are usually connected by penetration welding. Usually, a slot is opened in the pole terminal, and the bottom of the slot is penetrated and welded to the current collecting plate to achieve electrical connection. Technical Solutions

[0004] 18. The battery of claim 17, wherein the battery is configured to extend past a first end of the battery pack and past a second end of the battery pack to extend past the first end of the battery pack. The battery is configured to extend past a first end of the battery pack and past a second end of the battery pack to extend past the first end of the battery pack. The battery is configured to extend past a first end of the battery pack and past a second end of the battery pack to extend past the first end of the battery pack.

[0005] Optionally, the seal includes a column portion and a connecting portion, the column portion is inserted into the through hole, the connecting portion is arranged on a side of the column portion away from the first collecting plate and is arranged around the column portion, and the connecting portion is arranged outside the shell for welding and electrically connecting to the pole.

[0006] Optionally, the column portion is provided with a groove extending in the first direction, the column portion includes a bottom plate and side plates connected around the bottom plate, the bottom plate and the side plates enclose the groove, and the bottom plate has an inner bottom wall and an outer bottom wall arranged opposite to each other along the first direction; wherein, the outer bottom wall is welded and electrically connected to the first collecting plate, and the side plates are abutted against the inner wall of the through hole to seal the through hole.

[0007] Optionally, the orthographic projection of the inner wall surface of the side panel on the projection plane perpendicular to the first direction has two first contour points opposite to each other in the second direction, and a first line segment extending along the second direction is present between the two first contour points. The length A mm of the first line segment is the maximum dimension of the orthographic projection of the inner wall surface of the side panel on the projection plane in the second direction, 3mm≤A≤12mm; the first direction is orthogonal to the second direction.

[0008] Optionally, the orthographic projection of the outer wall surface of the side panel on the projection plane perpendicular to the first direction has two second contour points opposite to each other in the second direction, and a second line segment extending along the second direction is present between the two second contour points. The length B mm of the second line segment is the maximum dimension of the orthographic projection of the outer wall surface of the side panel on the projection plane in the second direction, wherein 3.5 mm ≤ B ≤ 17.5 mm, and satisfies: 0.3 ≤ A / B ≤ 0.99.

[0009] Optionally, the distance between the inner bottom wall and the outer bottom wall of the groove in the first direction is t1 mm, and the distance between the welded portions of the first collecting plate and the outer bottom wall in the first direction is t2 mm;

[0010] Satisfies at least one of the following characteristics:

[0011] i) 0.1mm≤t1≤2mm;

[0012] ii) 0.1mm≤t2≤1mm;

[0013] iii), 0.1≤t1 / t2≤5.

[0014] Optionally, the second end surface of the pole is provided with an annular platform surrounding the through hole, and the annular platform is provided with a first annular groove surrounding the through hole;

[0015] The connecting portion is embedded in the first annular groove, and the connecting portion is welded to the groove wall of the first annular groove.

[0016] Optionally, a second annular groove is formed on the connecting portion, and the sealing member is welded to the groove wall of the first annular groove of the pole through the groove wall of the second annular groove;

[0017] The orthographic projection of the area where the bottom wall is welded to the first collecting plate on a projection plane perpendicular to the first direction is located within the orthographic projection of the area where the second annular groove is welded to the first annular groove on a projection plane perpendicular to the first direction.

[0018] Optionally, a protrusion is provided on a surface of the first current collecting plate facing away from the electrode assembly in the first direction, the protrusion extends into the inner side of the through hole, and the protrusion is welded to the bottom plate.

[0019] Optionally, there is a gap between the outer wall of the protrusion and the inner wall of the through hole.

[0020] A second aspect of the embodiments of the present application provides a battery pack including the secondary battery described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic diagram of a first structure of a secondary battery provided in an embodiment of the present application;

[0022] FIG2 is an exploded view of FIG1 ;

[0023] FIG3 is a cross-sectional view taken along line EE of FIG1 ;

[0024] FIG4 is an enlarged structural diagram of point F in FIG3 ;

[0025] FIG5 is a schematic structural diagram of a post in a secondary battery provided in an embodiment of the present application;

[0026] FIG6 is a schematic diagram of a first structural example of a sealing member in a secondary battery provided in an embodiment of the present application;

[0027] FIG7 is a cross-sectional view taken along line GG of FIG6 ;

[0028] FIG8 is a cross-sectional view of a combination of a terminal and a seal in a secondary battery provided in an embodiment of the present application;

[0029] FIG9 is a schematic diagram of a second structure of a secondary battery provided in an embodiment of the present application;

[0030] FIG10 is a schematic diagram of a third structure of a secondary battery provided in an embodiment of the present application.

[0031] Explanation of the accompanying symbols: 1. secondary battery; 10. shell; 101. accommodating cavity; 11. opening; 20. electrode assembly; 21. main body; 22. pole ear; 221. first pole ear; 222. second pole ear; 30. first current collecting plate; 31. protrusion; 32. limiting protrusion; 40. pole column; 41. through hole; 401. first end face; 402. second end face; 42. ring platform; 43. first ring groove; 44. insulating gasket; 45. sealing ring; 46. rivet block; 50. sealing member; 501. column portion; 502. connecting portion; 51. first end; 52. second end; 53. groove; 531. Bottom wall, 5311, inner bottom wall, 5312, outer bottom wall, 532, side panel, 5321, first contour point, 5322, second contour point, 5323, third contour point, 5324, fourth contour point, 533, top surface, 54, second annular groove; 60, top cover; 70, second collecting plate; 80, sealing sheet; X, first direction, Y, second direction.

[0032] Implementation Methods of the Application

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0034] The present application provides a battery pack including a secondary battery.

[0035] In some embodiments of the present application, a secondary battery 1 is provided. Referring to FIG. 1 to FIG. 10 , the secondary battery 1 includes a housing 10 , an electrode assembly 20 , a first current collecting disk 30 , a terminal post 40 , and a seal 50 .

[0036] 1 to 4 , a housing 10 is provided with a housing 101, and the housing 10 has a first direction X. In the embodiment shown in FIG1 to 4 , the housing 10 is cylindrical in shape, the secondary battery 1 is a cylindrical battery, and the first direction X is the axial direction of the housing 10. In other implementations of the embodiment of the present application, the housing 10 can be square in shape to form a square battery. The housing 10 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0037] 2 to 4 and 9 to 10 , the electrode assembly 20 is disposed in the accommodating cavity 101 of the shell 10 , and the electrode assembly 20 extends along the first direction X. In the embodiment shown in FIG2 to 4 , the electrode assembly 20 includes a main body 21 and a pole tab 22 , and the main body 21 extends along the first direction X. The pole tab 22 includes a first pole tab 221 and a second pole tab 222 , and the first pole tab 221 is disposed at one end of the main body 21 in the first direction X, and the second pole tab 222 is disposed at the other end of the main body 21 in the first direction X.

[0038] The main body 21 includes electrode sheets and a separator. Specifically, the main body 21 includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is disposed between the positive electrode sheet and the negative electrode sheet to provide insulation between the positive and negative electrode sheets. The positive electrode sheet, separator, and negative electrode sheet are wound together to form the main body 21 of the electrode assembly 20. The first electrode tab 221 is the positive electrode tab, and the second electrode tab 222 is the negative electrode tab. The first electrode tab 221 is connected to the positive electrode sheet, and the second electrode tab 222 is connected to the negative electrode sheet. The positive electrode sheet is provided with a positive active material. One end of the positive electrode sheet in the first direction X is not provided with a positive active material to form the first electrode tab 221. The negative electrode sheet is provided with a negative active material. The other end of the negative electrode sheet in the first direction X is not provided with a negative active material to form the second electrode tab 222. Referring to Figures 2 to 4 and Figures 9 to 10, the electrode assembly 20 has a wound structure. In other implementations of the present application, the positive electrode sheet, the separator, and the negative electrode sheet are a laminated structure, which form the main body 21 of the electrode assembly 20 after being stacked.

[0039] In some embodiments of the present application, referring to Figures 2 to 4 , a first current collecting disk 30 is disposed in the accommodating cavity 101 of the housing 10 . The first current collecting disk 30 has a plate-like structure and is electrically connected to one end of the electrode assembly 20 in the first direction X. The first current collecting disk 30 is a positive electrode current collecting disk. The first current collecting disk 30 is disposed on an end surface of the electrode assembly 20 where the first electrode tab 221 is provided. The first current collecting disk 30 abuts against an end surface of the electrode assembly 20 where the first electrode tab 221 is provided. The first current collecting disk 30 is electrically connected to the electrode assembly 20 via the first electrode tab 221 .

[0040] Referring to Figures 2-4 and 9-10, the terminal 40 is fixedly connected to the housing 10 and partially located within the accommodating cavity 101. The terminal 40 is disposed on the side of the first current collecting plate 30 facing away from the electrode assembly 20 in the first direction X. A through hole 41 is defined in the terminal 40, extending through the terminal 40 in the first direction X. Referring to Figures 2-4, an opening 11 is defined on the end surface of the housing 10 proximate the first current collecting plate 30 in the first direction X. The terminal 40 is riveted into the opening 11. A portion of the terminal 40 in the first direction X is located outside the housing 10, while another portion of the terminal 40 in the first direction X is located inside the housing 10. The end of the terminal 40 located outside the housing 10 is electrically connected to an external electrical device. The first tab 221 of the electrode assembly 20 is electrically connected to the terminal 40 via the first current collecting plate 30. The terminal 40 is a positive terminal and constitutes the positive terminal of the secondary battery 1.

[0041] In some embodiments of the present application, referring to Figures 1 to 4 and Figures 6 to 10, the seal 50 is at least partially disposed in the through hole 41 of the pole 40 to seal the through hole 41. The seal 50 includes a first end 51 and a second end 52 arranged opposite to each other along the first direction X. The first end 51 is welded and fixed to the first current collecting disc 30. The seal 50 is electrically connected to the first current collecting disc 30 through the first end 51. The second end 52 is welded and fixed to the pole 40. The seal 50 is electrically connected to the pole 40 through the second end 52. The pole 40 is electrically connected to the first current collecting disc 30 through the seal 50.

[0042] In existing secondary batteries, the electrode and the current collecting plate are usually assembled by first riveting the electrode and the shell, and then performing penetration welding on the contact part of the electrode and the current collecting plate to achieve fixation and electrical connection between the two. However, during the riveting process of the electrode and the shell, the electrode will be offset, resulting in a gap between the end face of the electrode and the current collecting plate where it contacts the current collecting plate. The existence of this gap leads to poor welding during the penetration welding process, and there is a risk of cold welding at the position corresponding to the gap, which in turn affects the smoothness and stability of current transmission between the electrode assembly, the current collecting plate and the electrode, and affects the performance of the secondary battery.

[0043] The secondary battery 1 provided in the embodiment of the present application has a through hole 41 formed on the pole 40, and a sealing member 50 is provided in the through hole 41. The sealing member 50 blocks the through hole 41 to ensure the sealing of the accommodating cavity 101 of the shell 10. At the same time, the first end 51 of the sealing member 50 is welded and fixed to the first collecting disc 30 and electrically connected, and the second end 52 is welded and fixed to the pole 40 and electrically connected. The pole 40 does not need to be welded and fixed to the first collecting disc 30 to achieve electrical connection between the two. The pole 40 is electrically connected to the first collecting disc 30 through the sealing member 50. There is no welding relationship between the pole 40 and the first collecting disc 30, even if the pole 40 is riveted to the shell 10. Even if an offset occurs during the installation process, resulting in a gap between the pole 40 and the first current collecting disc 30, it will not affect the stability of the welded connection between the first end 51 of the seal 50 and the first current collecting disc 30. Moreover, the seal 50 can ensure that the end face of the first end 51 has good flatness during processing, so that the first current collecting disc 30 and the first end 51 fit more closely without any gap. During the penetration welding of the first end 51 and the first current collecting disc 30, there is no risk of cold welding, thereby ensuring the stability of current transmission between the electrode assembly 20, the first current collecting disc 30, the seal 50 and the pole 40, and ensuring the performance and stability of the secondary battery 1.

[0044] Optionally, the seal 50 is made of a conductive material, which may be the same material as the pole 40 .

[0045] In some embodiments of the present application, referring to Figures 6 to 8, the seal 50 includes a column portion 501 and a connecting portion 502. The column portion 501 is inserted into the through hole 41 of the pole 40 to block the through hole 41. The connecting portion 502 is arranged on a side of the column portion 501 away from the first current collecting disk 30 in the first direction X. The connecting portion 502 is arranged around the column portion 501. An end of the column portion 501 close to the first current collecting disk 30 in the first direction X forms a first end 51 of the seal 50. The column portion 501 is welded to the first current collecting disk 30 and is electrically connected. The column portion 501 and the connecting portion 502 at an end away from the column portion 501 in the first direction X form a second end 52 of the seal 50. The connecting portion 502 is arranged on the outside of the shell 10. The connecting portion 502 is used to be welded to and electrically connected to the pole 40.

[0046] In some embodiments of the present application, referring to Figures 3, 4, and 6 to 9, a groove 53 extending in a first direction X is defined in the column portion 501. The column portion 501 includes a bottom plate 531 and side plates 532 connected to the bottom plate 531. Referring to Figures 7 and 8, the bottom plate 531 includes an inner bottom wall 5311 and an outer bottom wall 5312 disposed opposite each other along the first direction X. The outer bottom wall 5312 is welded to and electrically connected to the first current collecting plate 30, and the side plates 532 abut against the inner wall of the through hole 41 of the terminal 40 to seal the through hole 41. The provision of the groove 53 reduces the thickness of the column portion 501 in the first direction X, facilitating welding and securing the bottom plate 531 to the first current collecting plate 30.

[0047] In some embodiments of the present application, referring to FIG. 7 , the orthographic projection of the inner wall surface of the side plate 532 of the sealing member 50 on a projection plane perpendicular to the first direction X has two first contour points 5321 and 5322 that are opposite in the second direction Y. The two first contour points 5321 and 5322 have a first line segment (not shown) extending along the second direction Y. The length of the first line segment is A mm, where A is the maximum dimension of the orthographic projection of the inner wall surface of the side plate 532 on the projection plane in the second direction Y, satisfying 3 mm ≤ A ≤ 12 mm. Specifically, the value of A can be any value among 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, and 12 mm, or a value between any two of these numbers. The first direction X is orthogonal to the second direction Y. When the value of A is within the above range, it can ensure the effective welding area of ​​the welding connection between the base plate 531 and the first current collecting disk 30, ensure the flow area between the electrode assembly 20, the first current collecting disk 30 and the seal 50, and will not affect the diameter of the pole 40, so that the diameter of the pole 40 is within a reasonable range and will not affect the connection between the pole 40 and external electrical equipment.

[0048] Among them, the first line segment is determined as follows: based on the contour line of the positive projection of the inner wall surface of the side panel 532 on the projection plane perpendicular to the first direction X, a circumscribed rectangle is drawn, and the contour line of the positive projection is inscribed in the rectangle. In the second direction Y, the circumscribed rectangle has two sides opposite to each other along the second direction Y. An extension line perpendicular to the second direction Y is drawn at the tangent point of the two sides and the contour line of the positive projection to form a first contour line. A line segment extending along the second direction Y and connecting the two first contour lines is made between the two first contour lines, which is the first line segment.

[0049] In some embodiments of the present application, referring to FIG7 , the orthographic projection of the outer wall surface of the side plate 532 of the seal 50 onto a projection plane perpendicular to the first direction X has two second contour points 5323 and 5324 that are opposite each other in the second direction Y. These two second contour points 5323 and 5324 define a second line segment (not shown) extending along the second direction Y. The length of the second line segment is B mm, where 3.5 mm ≤ B ≤ 17.5 mm. Specifically, the value of B can be any value among 3.5, 4.0, 7.0, 10.0, 12.0, 14.0, 16.0, and 17.0, or a value between any two of these numbers. B represents the maximum dimension of the orthographic projection of the outer wall surface of the side plate 532 onto the projection plane in the second direction Y. Furthermore, 0.3 ≤ A / B ≤ 0.99 is satisfied. Specifically, the value of A / B can be any value among 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 0.99, or a value between any two of these values. When the value of A / B is within this range, the wall thickness of the side plate 532 is within a reasonable range, ensuring the structural strength of the seal 50, preventing shaking or skewing of the seal 50 during welding to the first collecting plate 30, and ensuring a good welding effect.

[0050] Among them, the second line segment is determined as follows: based on the contour line of the positive projection of the outer wall surface of the side panel 532 on the projection plane perpendicular to the first direction, a circumscribed rectangle is drawn, and the contour line of the positive projection is inscribed in the rectangle. In the second direction Y, the circumscribed rectangle has two sides opposite to each other along the second direction Y. An extension line perpendicular to the second direction Y is drawn at the tangent point of the two sides and the contour line of the positive projection to form a second contour line. A line segment extending along the second direction Y and connecting the two second contour lines is made between the two second contour lines, which is the second line segment.

[0051] In some embodiments of the present application, referring to FIG7 , the distance between the inner bottom wall 5311 and the outer bottom wall 5312 of the groove 53 in the first direction X is t1 mm. Referring to FIG4 , the distance between the welded portions of the first current collecting tray 30 and the outer bottom wall 5312 in the first direction is t2 mm. In other words, t2 is the distance that the weld mark on the first current collecting tray 30 extends along the first direction X.

[0052] In some embodiments of the present application, 0.1 mm ≤ t1 ≤ 2 mm. Specifically, the value of t1 can be any value selected from the group consisting of 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1.0 mm, 1.3 mm, 1.5 mm, 1.7 mm, and 2 mm, or a value between any two of these values. When the value of t1 is within the aforementioned range, the thickness of the bottom plate 531 in the first direction X can be maintained within a reasonable range, thereby ensuring the weld strength and weld stability between the bottom plate 531 and the first current collecting tray 30 during penetration welding.

[0053] In some embodiments of the present application, 0.1 mm ≤ t2 ≤ 1 mm. Specifically, the value of t2 can be any value selected from the group consisting of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1.0 mm, or a value between any two of these values. When the value of t2 is within the aforementioned range, the weld between the first current collecting tray 30 and the bottom plate 531 can have a sufficient thickness, thereby ensuring the stability and firmness of the weld between the first current collecting tray 30 and the bottom plate 531 and avoiding the risk of a cold weld.

[0054] In some embodiments of the present application, 0.1 ≤ t1 / t2 ≤ 5. Specifically, the value of t1 / t2 can be any value among 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or a value between any two of these numbers. This ensures the stability and firmness of the weld between the bottom plate 531 and the first current collecting tray 30, avoids excessive welding energy waste, and reduces production costs.

[0055] In some embodiments of the present application, referring to FIG5 , the second end surface 402 of the terminal 40 is provided with an annular platform 42 surrounding the through hole 41. The annular platform 42 defines a first annular groove 43 surrounding the through hole 41. Referring to FIG8 , the connecting portion 502 of the seal 50 is embedded in the first annular groove 43 and welded to the first annular groove 43. Specifically, the connecting portion 502 is welded to the groove wall of the first annular groove 43 to achieve welded fixation and electrical connection between the seal 50 and the terminal 40. The provision of the first annular groove 43 provides space for the connecting portion 502 of the seal 50, thereby allowing the top surface 533 of the seal 50 to be flush with the second end surface 402 of the terminal 40 and to be on the same plane, ensuring smoothness and sealing, and facilitating subsequent connection to an external circuit.

[0056] In some embodiments of the present application, referring to Figures 6 to 8 , a second annular groove 54 is defined in the connection portion 502 of the seal 50. The seal 50 is welded to the first annular groove 43 of the terminal 40 via the second annular groove 54. The provision of the second annular groove 54 reduces the thickness of the connection portion 502 in the first direction X, thereby reducing the energy consumed during penetration welding between the connection portion 502 and the ring platform 42, while ensuring effective penetration welding.

[0057] In some embodiments of the present application, referring to Figures 4, 9, and 10, the orthographic projection of the area where the bottom plate 531 is welded to the first current collecting disc 30, on a projection plane perpendicular to the first direction X, is located within the orthographic projection of the area where the second annular groove 54 is welded to the first annular groove 43, on a projection plane perpendicular to the first direction X. This ensures that the welded connections between the seal 50 and the first current collecting disc 30 and between the seal 50 and the terminal 40 are not disturbed, ensuring smooth welding.

[0058] In some embodiments of the present application, referring to FIG. 9 , a protrusion 31 is provided on a surface of the first current collecting tray 30 facing away from the electrode assembly 20 in the first direction X. The protrusion 31 extends into the interior of the through-hole 41 and is welded to the bottom plate 531 of the seal 50. The structural design of the protrusion 31 on the first current collecting tray 30 allows the protrusion 31 to position the electrode post 40, allowing the body 501 of the seal 50 to be welded and electrically connected to the protrusion 31 of the first current collecting tray 30 within the through-hole 41. This reduces the material used in manufacturing the seal 50 and ensures weld stability between the seal 50 and the first current collecting tray 30.

[0059] In some embodiments of the present application, referring to Figure 10, a protrusion 31 is provided on a side of the first collecting plate 30 that is away from the electrode assembly 20 in the first direction X. The protrusion 31 extends into the inner side of the through hole 41 and extends to the inner bottom wall of the first annular groove 43. Specifically, the end surface of the protrusion 31 that is away from one end of the electrode assembly 20 in the first direction X is flush with the plane of the inner bottom wall of the first annular groove 43. The seal 50 is a flat sheet structure. The seal 50 is embedded in the first annular groove 43. The seal 50 is welded and electrically connected to the protrusion 31. The seal 50 is welded and electrically connected to the first annular groove 43 through the second annular groove 54.

[0060] In some embodiments of the present application, referring to Figures 9 and 10, there is a gap (not shown in the figures) between the outer wall of the protrusion 31 and the inner wall of the through hole 41, thereby avoiding contact between the protrusion 31 and the pole 40 and avoiding mixed connection between the first collecting plate 30 and the pole 40.

[0061] In some embodiments of the present application, referring to Figures 2, 4, 9, and 10, the secondary battery 1 further includes an insulating gasket 44, a sealing ring 45, and a rivet block 46. The insulating gasket 44, the sealing ring 45, and the rivet block 46 are riveted together to the housing 10 to form the positive terminal of the secondary battery 1.

[0062] The housing 10 has an opening 11 at one end proximal to the pole 40 in the first direction X. The end of the pole 40 in the first direction X, facing away from the first current collecting disc 30, extends out of the housing 10 through the opening 11 to connect to external devices. A sealing ring 45 is disposed within the housing cavity 101 of the housing 10. The sealing ring 45 surrounds the pole 40 and is embedded in the opening 11 to seal the pole 40 from the opening 11. An annular insulating gasket 44 surrounds the sealing ring 44. Its lower surface in the first direction X abuts against the first current collecting disc 30, while its upper surface in the first direction X abuts against the inner wall of the housing 10. This insulates the pole 40, the first current collecting disc 30, and the housing 10 from any short circuits.

[0063] The rivet block 46 surrounds the pole 40 and is annular in shape. The rivet block 46 is located outside the housing 10 and extends out of the outer end of the housing 10 around the pole 40. Specifically, the rivet block 46 is disposed between the rivet block 46 and the end surface of the housing 10 where the opening 11 is provided. The rivet block 46 is used to insulate the rivet block 46 and the housing 10 to prevent short circuits.

[0064] In some embodiments of the present application, referring to FIG. 2 and FIG. 3 , the secondary battery 1 further includes: a top cover 60 , a second current collecting plate 70 and a sealing sheet 80 .

[0065] The second current collecting disc 70 is electrically connected to one end of the electrode assembly 20 away from the electrode post 40 in the first direction X. In the embodiment of the present application, the second current collecting disc 70 is a negative electrode current collecting disc. The second current collecting disc 70 is disposed on an end surface of the electrode assembly 20 where the second electrode tab 222 is disposed. The second current collecting disc 70 abuts against an end surface of the electrode assembly 20 where the second electrode tab 222 is disposed. The second current collecting disc 70 is electrically connected to the electrode assembly 20 via the second electrode tab 222.

[0066] Referring to Figure 2 , the housing 10 is open at one end facing away from the terminal 40 in the first direction X. A top cover 60 is disposed over the opening. A liquid injection port (not shown) is defined in the top cover 60. A sealing sheet 80 is embedded in the liquid injection port to seal the top cover 60. The top cover 60, the second current collecting tray 70, and the sealing sheet 80 form the negative terminal of the secondary battery 1.

[0067] In order to illustrate that the technical solution provided in this application can well ensure that the overcurrent capacity of the battery cell meets the requirements by setting the specific value range of A, the specific value range of B and the proportional relationship between the two, Examples 1-14 are provided below for illustration.

[0068] Among them, the methods and requirements for overcurrent testing are:

[0069] Method 1: At room temperature of 25°C, the single battery is charged at a constant current of 2C, and the battery state of charge (SOC) is charged from 10% to 80%. The temperature of the welding point between the first collecting plate 30 and the bottom plate 531 is measured to be ≤60°C.

[0070] Method 2: At room temperature of 25°C, the single battery is charged at a constant current of 4C, and the battery state of charge (SOC) is charged from 10% to 80%. The temperature at the welding point between the first collecting plate 30 and the bottom plate 531 is measured to be ≤60°C.

[0071] In order to illustrate that the technical solution provided in the present application can well ensure the welding stability and firmness between the first collecting plate 30 and the bottom plate 531 by setting the specific value range of t1, the specific value range of t2 and the proportional relationship between the two, avoid the risk of cold welding or welding through, and the connection strength between the two, Examples 1-15 are provided below for illustration.

[0072] The welding effect is tested as follows: the penetration depth on the first collecting plate 30 is tested, penetration depth / t2≤0.9 to ensure no weld through; when t1>t2, penetration depth / t2≥0.4 to ensure no cold weld; when t1≤t2, penetration depth≥t1 to ensure no cold weld.

[0073] The connection strength test method is as follows: the first collecting plate 30 is welded to the bottom plate 531, and the welding area is guaranteed to be consistent for all schemes 8mm 2 , test the connection force F between the first collecting tray 30 and the bottom plate 531, with Newton (N) as the unit, and require F ≥ 50N; when testing the connection force F, the axis of the first collecting tray 30 and the axis of the bottom plate 531 are on the same axis, fix the seal 50, and apply displacement to the first collecting tray 30 to move the first collecting tray 30 in the direction away from the seal 50 until the connection between the two is completely separated. The maximum force of this process is F.

[0074] The above is a detailed introduction to a secondary battery and a battery pack provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for those skilled in the art, based on the ideas of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A secondary battery comprising: A housing having a receiving cavity therein, wherein the housing has a first direction; An electrode assembly, disposed in the accommodating cavity; A first current collecting plate, disposed in the accommodating cavity, the first current collecting plate being electrically connected to one end of the electrode assembly in the first direction; Wherein, the secondary battery further comprises: A pole, the pole is fixedly connected to the shell and partially located in the accommodating cavity, the pole is arranged on a side of the first current collecting disk away from the electrode assembly in the first direction, and a through hole is opened on the pole that penetrates the pole along the first direction; and A seal, wherein the seal is at least partially disposed in the through hole to seal the through hole, the seal comprises a first end and a second end disposed opposite to each other along the first direction, the first end is welded to and electrically connected to the first current collecting disk, the second end is welded to and electrically connected to the pole, and the pole is electrically connected to the first current collecting disk through the seal.

2. The secondary battery according to claim 1, wherein The seal includes a column portion and a connecting portion, the column portion is inserted into the through hole, the connecting portion is arranged on a side of the column portion away from the first current collecting plate and surrounds the column portion, and the connecting portion is arranged outside the shell for welding and electrical connection with the pole.

3. The secondary battery according to claim 2, wherein: The column portion is provided with a groove extending in the first direction, the column portion comprises a bottom plate and side plates connected around the bottom plate, the bottom plate and the side plates are combined to form the groove, and the bottom plate has an inner bottom wall and an outer bottom wall arranged opposite to each other along the first direction; The outer bottom wall is welded and electrically connected to the first current collecting plate, and the side plate abuts against the inner wall of the through hole to seal the through hole.

4. The secondary battery according to claim 3, wherein: The orthographic projection of the inner wall surface of the side plate on the projection plane perpendicular to the first direction has two first contour points opposite to each other in the second direction, and a first line segment extending along the second direction is provided between the two first contour points, and the length Amm of the first line segment is the maximum dimension of the inner wall surface of the side plate on the projection plane, wherein 3mm≤A≤12mm; The first direction is orthogonal to the second direction.

5. The secondary battery according to claim 3, wherein: The orthographic projection of the outer wall surface of the side panel on the projection plane perpendicular to the first direction has two second contour points opposite to each other in the second direction, and a second line segment extending along the second direction is provided between the two second contour points, and the length B mm of the second line segment is the maximum dimension of the outer wall surface of the side panel on the projection plane, wherein 3.5 mm≤B≤17.5 mm, and satisfies: 0.3≤A / B≤0.

99.

6. The secondary battery according to claim 3, wherein: The distance between the inner bottom wall and the outer bottom wall of the groove in the first direction is t1 mm, and the distance between the first current collecting plate and the outer bottom wall welded in the first direction is t2 mm; Satisfies at least one of the following characteristics: i) 0.1mm≤t1≤2mm; ii) 0.1mm≤t2≤1mm; iii), 0.1≤t1 / t2≤5.

7. The secondary battery according to claim 6, wherein: The second end surface of the pole is provided with a ring platform surrounding the through hole, and the ring platform is provided with a first ring groove surrounding the through hole; The connecting portion is embedded in the first annular groove, and the connecting portion is welded to the groove wall of the first annular groove.

8. The secondary battery according to claim 7, wherein: A second annular groove is provided on the connecting portion, and the sealing member is welded to the groove wall of the first annular groove of the pole through the groove wall of the second annular groove; The orthographic projection of the area where the bottom plate is welded to the first current collecting plate on a projection plane perpendicular to the first direction is located within the orthographic projection of the area where the second annular groove is welded to the first annular groove on a projection plane perpendicular to the first direction.

9. The secondary battery according to claim 3, wherein: A protrusion is provided on a surface of the first current collecting plate that is away from the electrode assembly in the first direction. The protrusion extends into the inner side of the through hole, and the protrusion is welded to the bottom plate.

10. The secondary battery according to claim 9, wherein There is a gap between the outer wall of the protrusion and the inner wall of the through hole.

11. A battery pack, wherein: The invention comprises the secondary battery according to any one of claims 1 to 10.

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