Secondary battery and battery pack

Abstract

A secondary battery and a battery pack. The secondary battery comprises a case (10), a battery cell (20), and a top cover assembly (30). The top cover assembly (30) comprises a cover plate (31), a pole structure (32), and a connecting sheet (33). The pole structure (32) is provided with a positioning hole (321). The connecting sheet (33) comprises a first connecting portion (331), a positioning portion (332), and a second connecting portion (333); the positioning portion (332) protrudes out of the first connecting portion (331) and is embedded in the positioning hole (321); and the size of the positioning portion (332) in a first direction is A mm, the maximum size of the positioning portion (332) in a second direction is Φ mm, and the inequation of 0.1≤A / Φ≤2 is satisfied.

Description

Secondary battery and battery pack

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 20, 2023, with application number 202323488285.1 and titled “A Secondary Battery and Battery Pack,” the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to, but is not limited to, the field of power battery technology. Background Art

[0003] The top cover assembly is a metal plate with a through-hole. The pole is divided into a base portion and an extension portion, with the base portion's cross-sectional area larger than the diameter of the through-hole. During assembly, the base portion is located below the top cover (i.e., inside the housing). After the extension portion passes through the through-hole, it is secured to the pole to the top cover using a retaining spring or rivets. SUMMARY OF THE INVENTION

[0004] In the first aspect, the present application provides a secondary battery, which has a first direction and a second direction perpendicular to each other, and the secondary battery includes a shell, a battery cell and a top cover assembly, the shell and the top cover assembly cooperate to enclose a closed space, and the battery cell is accommodated in the closed space; the top cover assembly includes a cover plate, a pole structure and a connecting piece, and the first direction is perpendicular to the cover plate; the pole structure has a positioning hole; the connecting piece includes a first connecting portion, a positioning portion and a second connecting portion, the positioning portion is protruding from the first connecting portion, the first connecting portion is electrically connected to the battery cell, the positioning portion is embedded in the positioning hole, the second connecting portion is located at the end of the positioning portion away from the first connecting portion, and the second connecting portion is electrically connected to the pole structure, the size of the positioning portion in the first direction is Amm, and the maximum size of the positioning portion in the second direction is Φmm, satisfying: 0.1≤A / Φ≤2.

[0005] Optionally, the positioning portion is cross-sectioned perpendicular to the first direction to obtain a cross section, and the cross-sectional area of ​​the positioning portion gradually decreases along the direction from the first connecting portion to the second connecting portion; the positioning portion has an outer wall, and the angle between the outer wall and the first direction is α, and the range of α is 0°~30°.

[0006] Optionally, the positioning portion has an outer wall, the outer wall includes at least two first wall surfaces, each first wall surface is adjacent to each other and is set at an angle, the inner side surface of the positioning hole includes at least two second wall surfaces, each second wall surface is adjacent to each other and is set at an angle, when the positioning portion is embedded in the positioning hole, the first wall surface and the second wall surface are arranged opposite to each other and cooperate with each other to limit the rotation of the positioning portion in the positioning hole.

[0007] Optional, A is 2mm~10mm, Φ is 5mm-20mm.

[0008] Optionally, the cover plate has a connecting hole, the pole structure includes a sealing ring and a pole body, and the pole body is embedded in the sealing ring; the sealing ring is passed through the connecting hole to separate the cover plate and the pole body.

[0009] Optionally, the pole body includes a main body, a first fixing part and a second fixing part, the main body is passed through the connecting hole, the first fixing part and the second fixing part are respectively located at the two ends of the main body in the first direction, the first fixing part and the second fixing part cooperate to clamp the cover plate to fix the pole body to the cover plate, wherein the positioning hole is located in the main body, and the positioning hole is a blind hole.

[0010] Optionally, the positioning hole is located in the sealing ring, the positioning hole is a through hole, the pole body is embedded in a side of the sealing ring away from the connecting piece, and the second connecting portion passes through the positioning hole and is electrically connected to the pole body.

[0011] Optionally, the cover plate is provided with a liquid injection port, the first connecting portion is provided with an avoidance groove, and the orthographic projection of the avoidance groove on the cover plate covers the liquid injection port.

[0012] Optionally, the first connecting portion includes a first sub-portion and a second sub-portion connected to each other, the positioning portion is located in the first sub-portion, and an orthographic projection area of ​​the first sub-portion on the cover plate is smaller than an orthographic projection area of ​​the second sub-portion on the cover plate.

[0013] Optionally, the first connecting portion further includes an anti-short-circuit portion, which is connected between the first sub-portion and the second sub-portion, the connecting piece has a third direction, and the anti-short-circuit portion extends along the third direction; and / or a groove structure is provided on the side where the second connecting portion abuts the pole structure.

[0014] In a second aspect, a battery pack is provided, comprising any of the aforementioned secondary batteries, the battery pack further comprising a box in which the secondary batteries are housed. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0016] FIG1 is a schematic structural diagram of a connecting piece provided in an embodiment of the present application.

[0017] FIG. 2 is a bottom view of FIG. 1 .

[0018] FIG3 is a cross-sectional view of a top cover assembly provided in an embodiment of the present application.

[0019] FIG4 is a schematic structural diagram of another connecting piece provided in an embodiment of the present application.

[0020] FIG. 5 is a bottom view of FIG. 4 .

[0021] FIG6 is a schematic diagram of a slot structure provided in an embodiment of the present application.

[0022] FIG7 is a schematic diagram of another slot structure provided in an embodiment of the present application.

[0023] FIG8 is a schematic diagram of another slot structure provided in an embodiment of the present application.

[0024] FIG9 is a schematic structural diagram of a secondary battery provided in an embodiment of the present application.

[0025] FIG10 is a schematic diagram of the battery cell installation provided in an embodiment of the present application.

[0026] FIG11 is a cross-sectional view of another top cover assembly provided in an embodiment of the present application.

[0027] FIG12 is a schematic diagram of an anti-short circuit portion provided in an embodiment of the present application.

[0028] FIG13 is a schematic diagram of another anti-short-circuit portion provided in an embodiment of the present application. Modes for Carrying Out the Invention

[0029] 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 embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0030] Since the base of the pole is located inside the shell, and the connecting piece is connected to the surface of the lower pole by overlapping, the space utilization inside the shell is reduced, thereby reducing the energy density of the power battery. In order to solve the technical problems of low space utilization and low energy density of secondary batteries, one embodiment of the present application provides a secondary battery. The secondary battery has a first direction and a second direction that are perpendicular to each other. It should be noted that the verticality mentioned in the embodiment of the present application is not limited to an absolute verticality of 90°. It can be understood that the angle between the first direction and the second direction can also be considered to be perpendicular to each other within a certain range. For example, the angle between the first direction and the second direction is 80°-100°. The above-mentioned certain range can be adjusted according to different scenarios.

[0031] The secondary battery includes a shell, a battery cell, and a top cover assembly. The shell and the top cover assembly cooperate to enclose a sealed space in which the battery cell is housed. The top cover assembly includes a cover plate, a pole structure, and a connecting piece, and the first direction is perpendicular to the cover plate. The pole structure has a positioning hole. The connecting piece includes a first connecting portion, a positioning portion, and a second connecting portion. The positioning portion is protruding from the first connecting portion and is electrically connected to the battery cell. The positioning portion is embedded in the positioning hole. The second connecting portion is located at the end of the positioning portion away from the first connecting portion and is electrically connected to the pole structure. The size of the positioning portion in the first direction is A mm, and the maximum size of the positioning portion in the second direction is Φ mm, satisfying the following: 0.1≤A / Φ≤2. It is worth noting that the size of the positioning portion in the first direction refers to the vertical distance in the first direction between the surface of the positioning portion on the side away from the first connecting portion and the surface of the positioning portion on the side close to the first connecting portion. This will be explained in detail below.

[0032] Please refer to Figures 2 and 9. In one embodiment, the secondary battery has a first direction (as shown by direction Z in Figure 2, the same below) and a second direction (as shown by direction X in Figure 2, the same below) that are perpendicular to each other. The secondary battery includes a shell 10, a battery cell 20 and a top cover assembly 30. The top cover assembly 30 cooperates with the shell 10 to form a closed space. The battery cell 20 is accommodated in the closed space, and the battery cell 20 is electrically connected to the top cover assembly 30 through the tab 21.

[0033] Referring to Figures 1, 2, 3, and 10, in some embodiments, the top cover assembly 30 includes a cover plate 31, a pole structure 32, and a connecting piece 33. The pole structure 32 is provided on the cover plate 31. One end of the connecting piece 33 is electrically connected to the tab 21 of the battery cell 20, and the other end of the connecting piece 33 is electrically connected to the pole structure 32. The pole structure 32 has a positioning hole 321. The connecting piece 33 includes a first connecting portion 331, a positioning portion 332, and a second connecting portion 333. The positioning portion 332 is protruding from the top of the pole structure 32. The first connecting portion 331 and the positioning portion 332 are embedded in the positioning hole 321. The second connecting portion 333 is located at the end of the positioning portion 332 away from the first connecting portion 331. That is, the first connecting portion 331 and the second connecting portion 333 are separated in the first direction. This improves the space utilization of the battery cell 20 and thereby increases the energy density of the secondary battery. The positioning portion 332 is arranged as a raised portion, which facilitates the positioning between the connecting piece 33 and the cover plate 31, prevents the connecting piece 33 from tilting or shifting, and improves assembly efficiency. It is worth noting that the positioning portion 332 is raised away from the first connecting portion 331 along the first direction Z.

[0034] It should be noted that the first connection portion 331 is provided with a through hole, and one end of the positioning portion 332 is connected to the edge of the first connection portion 331 having the through hole, and extends in the direction of the second connection portion 333 and is connected to the edge of the second connection portion 333. In some embodiments, the first connection portion 331, the positioning portion 332, and the second connection portion 333 are integrally formed, such as by stamping the positioning portion 332 and the second connection portion 333. The first connection portion 331 is electrically connected to the tab 21, and the second connection portion 333 is electrically connected to the pole structure 32 (as shown in FIG10, FIG10 is a schematic diagram of the battery cell installation provided in an embodiment of the present application). In this embodiment, the connection is achieved by laser welding. In other embodiments, ultrasonic welding or resistance welding can also be used, but are not limited to these. In actual production, the tab 21 is first welded to the first connection portion 331. After the tab 21 is connected, the second connection portion 333 is positioned in the positioning hole 321 by the positioning portion 332, and the second connection portion 333 is welded to the pole structure 32. In some embodiments, the first connecting portion 331 is provided with an escape groove 3311, and the cover plate 31 is provided with a liquid injection port. The orthographic projection of the escape groove 3311 on the cover plate 31 covers the liquid injection port. This configuration facilitates liquid injection and reduces the material used in the connecting piece 33, thereby reducing the weight of the connecting piece 33. It is worth noting that the escape groove 3311 is formed by retracting the first connecting portion 331 inward in the second direction X from the end away from the positioning portion 332 toward the positioning portion 332. That is, the bottom surface of the escape groove 3311 refers to the surface of the escape groove 3311 on the side of the avoidance groove 3311 closer to the positioning portion 332 in the second direction X. Of course, in other embodiments, the escape groove 3311 may be omitted, and the liquid injection port can be avoided by rotating the first connecting portion 331 180°. Other configurations are also possible, which are not described here.

[0035] Please continue to refer to Figure 1. In one embodiment, the first connecting portion 331 includes a first sub-portion 3312 and a second sub-portion 3313. The positioning portion 332 is located in the first sub-portion 3312. The orthographic projection area of ​​the first sub-portion 3312 on the cover plate 31 is smaller than the orthographic projection area of ​​the second sub-portion 3313 on the cover plate 31. This arrangement further achieves the lightweighting of the connecting piece 33.

[0036] Please continue to refer to Figure 2. In one embodiment, when the positioning portion 332 is cross-sectioned perpendicular to the first direction, a circular cross-section can be obtained. Along the direction from the first connection portion 331 to the second connection portion 333, the cross-sectional area of ​​the positioning portion 332 gradually decreases (that is, the cross-sectional area obtained by cross-sectioning the positioning portion 332 near the first connection portion 331 is larger than the cross-sectional area obtained by cross-sectioning the positioning portion 332 near the second connection portion 333), and the positioning portion 332 has an outer wall, and the angle between the outer wall and the first direction is α, and the range of α is 0°~30°. For example, when the positioning portion 332 has a side shape of a truncated cone structure, the first bottom surface of the truncated cone structure coincides with the plane in which the first connecting portion 331 extends, and the second bottom surface of the truncated cone structure coincides with the plane in which the second connecting portion 333 extends. At this time, both the first bottom surface and the second bottom surface are circular surfaces, and the radius of the second bottom surface is smaller than the radius of the first bottom surface. At the same time, the outer wall of the positioning portion 332 is the side of the truncated cone structure, and the cross-section obtained by cross-sectioning the positioning portion 332 perpendicular to the first direction is a circular cross-section; and when the cross-section obtained by cross-sectioning the positioning portion 332 perpendicular to the first direction is a hexagonal structure, there are a total of six outer walls of the positioning portion 332, and from the first connecting portion 331 to the second connecting portion 333, the distance between each outer wall of the positioning portion 332 and the central axis of the hexagonal structure gradually decreases. In this embodiment, an angle of 30° and a side shape of the positioning portion 332 presenting a truncated cone structure are used as an example for explanation. The positioning portion 332 is cut along the central axis of the truncated cone structure. In the obtained cross-sectional surface, the angle α formed by the central axis and the straight line in the extension direction of the cross-sectional surface is 30°. By setting the angle α, the nesting cooperation between the positioning portion 332 and the positioning hole 321 is facilitated.

[0037] It should be noted that the cross section is a surface perpendicular to the first direction. In addition, in some embodiments, due to manufacturing differences, the cross-sectional areas of two particularly close points do not necessarily decrease in practice, and are gradually decreasing according to the overall trend. The larger the size of the positioning portion 332 in the first direction, the larger the value of α. Such a setting can increase the stability of the positioning portion 332 nested in the positioning hole 321, and the measurement method of α can be to cut the positioning portion 332 through the cross section of the central axis of the positioning portion 332, and then measure the angle using an angle measuring tool, such as a protractor, or to measure the angle by taking pictures under a microscope, but is not limited to this.

[0038] Please refer to Figures 4 and 5. In one embodiment, the outer side wall of the positioning portion 332 includes at least two first wall surfaces 3321, each of which is adjacent to each other and is set at an angle. The inner side surface of the positioning hole 321 includes at least two second wall surfaces 3211 (as shown in Figure 11, Figure 11 is a cross-sectional view of another top cover assembly provided by an embodiment of the present application), and each second wall surface 3211 is also adjacent to each other and is set at an angle. When the positioning portion 332 is embedded in the positioning hole 321, the first wall surface 3321 and the second wall surface 3211 are arranged opposite to each other and cooperate with each other to limit the positioning portion 332 in the positioning hole. 321 rotates; in this embodiment, there are six first wall surfaces 3321, that is, the cross section of the positioning portion 332 is a hexagon, and six second wall surfaces 3211 are also provided on the inner side surface of the corresponding positioning hole 321. In other embodiments, it can be a pentagon or other shapes. It is not limited to this. Through the arrangement of the first wall surface 3321 and the second wall surface 3211, the connection piece 33 can be prevented from twisting. During welding installation, when the positioning portion 332 is embedded in the positioning hole 321, the position of the connection piece 33 is fixed, thereby ensuring welding quality and welding efficiency, and improving assembly efficiency.

[0039] Please continue to refer to Figure 3. In one embodiment, the cover plate 31 has a connecting hole 311, and the pole structure 32 includes a sealing ring 322 and a pole body 323. The pole body 323 is embedded in the sealing ring 322, and the sealing ring 322 is passed through the connecting hole 311 to separate the cover plate 31 and the pole body 323. The setting of the sealing ring 322 can separate the pole body 323 from the cover plate 31 to ensure the safety of the secondary battery.

[0040] The pole body 323 includes a main body 3232, a first fixing part 3231 and a second fixing part 3233. The main body 3232 is passed through the connecting hole 311. The first fixing part 3231 and the second fixing part 3233 are respectively located at the two ends of the main body 3232 in the first direction. The cover plate 31 is clamped by the cooperation of the first fixing part 3231 and the second fixing part 3233 to fix the pole body 323 on the cover plate 31. In this embodiment, the positioning hole 321 is set on the main body 3232, and the positioning hole 321 is a blind hole.

[0041] It should be noted that the pole body 323 is fixed in the connection hole 311 on the cover plate 31 by the first fixing portion 3231 and the second fixing portion 3233, and the pole body 323 and the connection hole 311 are separated by a sealing ring 322, which will not be described in detail here; the positioning hole 321 is a blind hole, that is, the second connecting portion 333 abuts the bottom of the positioning hole 321 and is welded to the positioning hole 321. In other embodiments, the pole body 323 and the positioning hole 321 can also be arranged in other forms. For example, in the embodiment shown in Figure 11, the positioning hole 321 is provided on the sealing ring 322, and the positioning hole 321 is a through hole. The pole body 323 is embedded in the side of the sealing ring 322 away from the connecting piece 33. The second connecting portion 333 passes through the positioning hole 321 and abuts against the pole body 323, and a welding operation is performed. This is not limited to this and can also be arranged in other forms, which will not be described in detail here.

[0042] Please refer to Figure 12. In one embodiment, the first connecting portion 331 also includes an anti-short-circuit portion 3314, which is arranged between the first sub-portion 3312 and the second sub-portion 3313, that is, the anti-short-circuit portion 3314 connects the first sub-portion 3312 and the second sub-portion 3313. Current or electrons are transmitted from the first sub-portion 3312 to the second sub-portion 3313 via the anti-short-circuit portion 3314, or current or electrons are transmitted from the second sub-portion 3313 to the first sub-portion 3312 via the anti-short-circuit portion 3314. When a short circuit occurs, the anti-short-circuit portion 3314 can disconnect the connection between the first sub-portion 3312 and the second sub-portion 3313 to ensure the safety of battery use. The connecting piece 33 has a third direction (as shown by direction Y in Figure 12, the same below), and the third direction Y intersects with both the first direction Z and the second direction X. The anti-short-circuit portion 3314 extends in a strip shape along the third direction. In this embodiment, the anti-short-circuit portion 3314 is narrower than the first sub-portion 3312 and the second sub-portion 3313, that is, the length in the third direction is smaller than the length of the first sub-portion 3312 and the second sub-portion 3313 in the third direction. The current flow capacity of the anti-short-circuit portion 3314 is smaller than the current flow capacity of the first sub-portion 3312 and the second sub-portion 3313. When a short circuit occurs, the current of the anti-short-circuit portion 3314 is too large and the anti-short-circuit portion 3314 melts, thereby ensuring the safety of the battery.

[0043] It should be noted that the strip-shaped arrangement of the anti-short-circuit portion 3314 can ensure that the anti-short-circuit portion 3314 is promptly blown when a battery short circuit occurs, and the strip-shaped arrangement can reduce the horizontal size (from the perspective of Figure 12) of the connecting piece 33. Specifically, the strip-shaped arrangement can reduce the size of the connecting piece 33 in the second direction X, which is conducive to a compact structure. In other embodiments, the anti-short-circuit portion 3314 can also be arranged in other forms. For example, in the embodiment shown in Figure 13, the melting point of the anti-short-circuit portion 3314 is lower than the melting point of the first sub-section 3312 and the second sub-section 3313. When a short circuit occurs, the temperature of the connecting piece 33 rises, and the anti-short-circuit portion 3314 blows before the first sub-section 3312 and the second sub-section 3313, thereby ensuring the safety of the battery. This is not limited to this.

[0044] Please refer to Figures 6 to 8. A groove structure 3331 is provided on the side where the second connecting part 333 abuts the pole structure 32, that is, the surface where the second connecting part 333 is welded to the pole body 323 is provided with a groove structure 3331. The notch of the groove structure 3331 is provided on the surface of the second connecting part 333 facing the pole body 323, which can increase the laser absorption effect and effectively improve the situation of poor laser welding and insufficient penetration. The groove structure 3331 can be a point groove, a strip groove or an annular groove. The groove structure 3331 can be formed by a stamping process or an etching process, which is not specifically limited here, as long as it meets the welding requirements.

[0045] It should be noted that the entire connecting piece 33 can also be formed by stamping, which will not be described in detail here.

[0046] In some embodiments, the size of the positioning portion 332 in the first direction is A mm, and A satisfies: 2≤A≤10, for example, 2, 6, 10, etc.; the maximum size of the positioning portion 332 in the second direction is Φ mm, and Φ satisfies: 5≤Φ≤20, for example, 5, 6, 10, 20, etc.; and A and Φ also satisfy: 0.1≤A / Φ≤2, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, etc.; in this way, this embodiment can improve the energy density and current capacity of the battery by reasonably setting the size of the positioning portion 332 in the first direction and the maximum size of the positioning portion 332 in the second direction.

[0047] To sum up, the secondary battery provided in the present application uses the positioning portion 332 to space the first connecting portion 331 and the second connecting portion 333, thereby increasing the space utilization rate of the battery cell 20, and the positioning portion 332 is embedded in the positioning hole 321, which facilitates the positioning between the connecting piece 33 and the cover plate 31, prevents the connecting piece 33 from tilting and offsetting, and improves assembly efficiency; at the same time, the ratio between the size of the positioning portion 332 in the first direction and the maximum size of the positioning portion 332 in the second direction is limited, thereby improving the energy density of the secondary battery while improving the current capacity.

[0048] The following structural examples are used to evaluate the performance of the technical solutions provided in the embodiments of this application.

[0049] Examples 1 to 8 and Comparative Examples 1 to 2 are provided. Taking a battery with a total height of 100 mm as an example, when A = 0, the energy density T is 500 Wh / mm³. The flow capacity is reflected by the maximum flow area S; a larger S indicates better flow capacity. However, to meet the charge and discharge rate requirements of the secondary battery and ensure its practicality, the minimum flow area is 20 mm². Specific parameters and test results are detailed in Table 1.

[0050] Table 1

[0051] Item A / mmΦ / mmTotal battery height / mmA / ΦT / Wh / mm³S / mm²Example 1251000.451020Example 22101000.251078.5Example 32201000.1510314Example 466100153228.3Example 56201000.3532314Example 6105100255520Example 71010100155578.5Example 810201000.5555314Comparative Example 12221000.09 / / Comparative Example 21041002.555512.56

[0052] It should be noted that T=500*[100 / (100-A)], S=π*(Φ / 2)²; from Examples 1-8, it can be seen that when the value of A / Φ satisfies: 0.1≤A / Φ≤2, the energy density T satisfies: 510≤T≤555, both of which are greater than 500. The design of the connecting piece 33 within the scope of the above embodiment can improve the space utilization while ensuring the energy density and flow capacity of the battery; on the other hand, in Comparative Example 1, A / Φ=0.09, the Φ value is too large at this time, and the battery The cover plate 31 has insufficient space, and the connecting piece 33 is close to the edge of the cover plate 31 or the shell 10, which affects the design of the edge plastic part and the welding of the cover plate 31. To make the value of A / Φ smaller, A needs to be smaller and / or Φ needs to be larger. Both Φ values ​​do not meet the use requirements. In comparative example 2, A / Φ=2.5, at this time the Φ value is too small, S is less than 20mm², and cannot meet the use requirements of the battery flow area. To make the value of A / Φ larger, A needs to be larger and / or Φ needs to be smaller. Both Φ values ​​do not meet the use requirements of the flow area.

[0053] On the other hand, the secondary battery in any of the above embodiments may be used in a battery pack, which further includes a box in which the secondary battery is accommodated.

[0054] 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 secondary battery of the present application and its core concept. At the same time, for those skilled in the art, according to the concept of the present application, there may be changes in the specific implementation methods and application scope. In summary, the contents of this specification should not be understood as limiting the present application.

[0055] Reference numerals in the figure: 10, shell; 20, battery cell; 21, tab; 30, top cover assembly; 31, cover plate; 311, connecting hole; 32, pole structure; 321, positioning hole; 3211, second wall; 322, sealing ring; 323, pole body; 3231, first fixing part; 3232, main body; 3233, second fixing part; 33, connecting piece; 331, first connecting part; 3311, avoidance groove; 3312, first sub-part; 3313, second sub-part; 3314, anti-short circuit part; 332, positioning part; 3321, first wall; 333, second connecting part; 3331, groove structure.

Claims

1. A secondary battery, the secondary battery having a first direction (Z) and a second direction (X) perpendicular to each other, the secondary battery comprising a housing (10), a battery cell (20) and a top cover assembly (30), the housing (10) and the top cover assembly (30) cooperating to enclose a closed space, the battery cell (20) being accommodated in the closed space; The top cover assembly (30) comprises a cover plate (31), a pole structure (32) and a connecting piece (33), and the first direction (Z) is perpendicular to the cover plate (31); The pole structure (32) has a positioning hole (321); The connecting piece (33) comprises a first connecting portion (331), a positioning portion (332) and a second connecting portion (333); the positioning portion (332) is protruding from the first connecting portion (331); the first connecting portion (331) is electrically connected to the battery cell (20); the positioning portion (332) is embedded in the positioning hole (321); the second connecting portion (333) is located at an end of the positioning portion (332) away from the first connecting portion (331); and the second connecting portion (333) is electrically connected to the pole structure (32); the dimension of the positioning portion (332) in the first direction (Z) is A mm; the maximum dimension of the positioning portion (332) in the second direction (X) is Φ mm, satisfying: 0.1≤A / Φ≤2.

2. The secondary battery according to claim 1, wherein The positioning portion (332) is cut perpendicularly to the first direction (Z) to obtain a cross section, wherein the cross-sectional area of ​​the positioning portion (332) gradually decreases along the direction from the first connecting portion (331) to the second connecting portion (333); The positioning portion (332) has an outer wall, and the angle between the outer wall and the first direction (Z) is α, and the range of α is 0°~30°.

3. The secondary battery according to claim 1, wherein The positioning portion (332) has an outer wall, the outer wall includes at least two first wall surfaces (3321), each of the first wall surfaces (3321) is adjacent to each other and is arranged at an angle, the inner side surface of the positioning hole (321) includes at least two second wall surfaces (3211), each of the second wall surfaces (3211) is adjacent to each other and is arranged at an angle, when the positioning portion (332) is embedded in the positioning hole (321), the first wall surface (3321) and the second wall surface (3211) are arranged opposite to each other and cooperate with each other to limit the rotation of the positioning portion (332) in the positioning hole (321).

4. The secondary battery according to claim 1, wherein A is 2mm~10mm, Φ is 5mm-20mm.

5. The secondary battery according to claim 1, wherein The cover plate (31) has a connection hole (311), and the pole structure (32) comprises a sealing ring (322) and a pole body (323), wherein the pole body (323) is embedded in the sealing ring (322); the sealing ring (322) is passed through the connection hole (311) to separate the cover plate (31) and the pole body (323).

6. The secondary battery according to claim 5, wherein: The pole body (323) comprises a main body (3232), a first fixing part (3231) and a second fixing part (3233); the main body (3232) is arranged to pass through the connecting hole (311); the first fixing part (3231) and the second fixing part (3233) are respectively located at two ends of the main body (3232) in the first direction (Z); the first fixing part (3231) and the second fixing part (3233) cooperate to clamp the cover plate (31) so as to fix the pole body (323) to the cover plate (31); wherein the positioning hole (321) is located in the main body (3232); and the positioning hole (321) is a blind hole.

7. The secondary battery according to claim 5, wherein: The positioning hole (321) is located on the sealing ring (322), the positioning hole (321) is a through hole, the pole body (323) is embedded on a side of the sealing ring (322) away from the connecting piece (33), and the second connecting portion (333) passes through the positioning hole (321) to be electrically connected to the pole body (323).

8. The secondary battery according to claim 1, wherein The cover plate (31) is provided with a liquid injection port, and the first connecting portion (331) is provided with an avoidance groove (3311), wherein the orthographic projection of the avoidance groove (3311) on the cover plate (31) covers the liquid injection port.

9. The secondary battery according to claim 1, wherein The first connecting portion (331) comprises a first sub-portion (3312) and a second sub-portion (3313) which are connected to each other, and the positioning portion (332) is located at the first sub-portion (3312), wherein the orthographic projection area of ​​the first sub-portion (3312) on the cover plate (31) is smaller than the orthographic projection area of ​​the second sub-portion (3313) on the cover plate (31).

10. The secondary battery according to claim 9, wherein The first connecting portion (331) further comprises an anti-short circuit portion (3314), wherein the anti-short circuit portion (3314) is connected between the first sub-portion (3312) and the second sub-portion (3313), the connecting piece (33) has a third direction (Y), the third direction (Y) intersects with both the first direction (Z) and the second direction (X), and the anti-short circuit portion (3314) extends along the third direction (Y).

11. The secondary battery according to claim 9, wherein A groove structure (3331) is provided on one side of the second connecting portion (333) abutting against the pole structure (32).

12. The secondary battery according to claim 9, wherein The first connecting portion (331) further comprises an anti-short circuit portion (3314), wherein the anti-short circuit portion (3314) is connected between the first sub-portion (3312) and the second sub-portion (3313), the connecting piece (33) has a third direction (Y), the anti-short circuit portion (3314) extends along the third direction (Y), and a groove structure (3331) is provided on one side of the second connecting portion (333) abutting against the pole structure (32).

13. The secondary battery according to claim 10 or 12, wherein: The length of the anti-short circuit portion (3314) in the third direction (Y) is smaller than the length of the first sub-portion (3312) and the second sub-portion (3313) in the third direction (Y).

14. The secondary battery according to claim 10 or 12, wherein: The melting point of the anti-short circuit portion (3314) is lower than the melting points of the first sub-portion (3312) and the second sub-portion (3313). 15 . A battery pack, comprising the secondary battery according to claim 1 , the battery pack further comprising a box, wherein the secondary battery is accommodated in the box.

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