Secondary battery and battery pack

Abstract

The utility model discloses a secondary battery and a battery pack, the secondary battery has a first direction and a second direction, and the secondary battery comprises a shell, a battery cell and a top cover assembly; the top cover assembly comprises a cover plate, a pole structure and a connecting piece, and the first direction is perpendicular to the cover plate; the pole structure is provided with a positioning hole; the connecting piece comprises a first connecting part, a positioning part and a second connecting part, the positioning part is arranged on the first connecting part in a protruding mode, the first connecting part is electrically connected with the battery cell, the positioning part is embedded in the positioning hole, the second connecting part is located at the end, away from the first connecting part, of the positioning part, the second connecting part is electrically connected with the pole structure, the size of the positioning part in the first direction is Amm, and the size of the positioning part in the second direction is Amm. The maximum size of the positioning part in the second direction is phi mm, and A / phi is larger than or equal to 0.1 and smaller than or equal to 2. And the first connecting part and the second connecting part are arranged at an interval through the positioning part, so that the space utilization rate of the battery cell is increased, the energy density of the secondary battery is improved, and meanwhile, the overcurrent capability is improved.

Description

Technical Field

[0001] The present application relates to the technical field of power batteries, and in particular to a secondary battery and a battery pack. Background Art

[0002] In the top cover plate assembly of the existing battery, the top cover plate is a metal plate with a through hole, and the pole is divided into a base part and an extension part, and the cross-sectional area of ​​the base part is larger than the aperture of the through hole. During assembly, the base part is located below the top cover plate (i.e., inside the shell), and after the extension part passes through the through hole, the extension part is fixed by a retaining spring or riveting, and the pole is fixed to the top cover plate in this way. Since the base part is located inside the shell, the connecting piece overlaps and connects with the surface of the lower pole, which reduces the space utilization inside the shell, thereby reducing the energy density of the power battery.

[0003] Therefore, it is necessary to improve the existing technology. Utility Model Content

[0004] The utility model aims to solve at least one of the technical problems existing in the prior art and provides a secondary battery and a battery pack.

[0005] According to one aspect of the present application, the present application provides a secondary battery, which has a first direction and a second direction perpendicular to each other, and includes a shell, a battery cell and a top cover assembly, the shell and the top cover assembly cooperate to enclose a confined space, and the battery cell is accommodated in the confined 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.

[0006] Further, the positioning portion is cut perpendicularly 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;

[0007] The positioning portion has an outer wall, and an included angle between the outer wall and the first direction is α, and the range of α is 0° to 30°.

[0008] Optionally, the positioning portion has an outer wall, which includes at least two first wall surfaces, each of which is adjacent to each other and is set at an angle, and the inner side surface of the positioning hole includes at least two second wall surfaces, each of which is adjacent to each other and is set at an angle, and 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.

[0009] Furthermore, A is 2 mm to 10 mm, and Φ is 5 mm to 20 mm.

[0010] Furthermore, the cover plate has a connecting hole, and the pole structure includes a sealing ring and a pole body, and the pole body is embedded in the sealing ring; the sealing ring passes through the connecting hole to separate the cover plate and the pole body.

[0011] Further, 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.

[0012] Furthermore, 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 to be electrically connected to the pole body.

[0013] Furthermore, 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.

[0014] Furthermore, 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.

[0015] Further, the first connecting portion further comprises an anti-short circuit portion, the anti-short circuit portion 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,

[0016] A groove structure is provided on one side of the second connecting portion abutting against the pole structure.

[0017] According to another aspect of the present application, a battery pack is provided, comprising any of the aforementioned secondary batteries, the battery pack further comprising a box, the secondary battery being accommodated in the box.

[0018] The beneficial effects of the present application are as follows: different from the prior art, the secondary battery provided by the present application uses a positioning portion to space the first connecting portion and the second connecting portion, thereby increasing the space utilization rate of the battery cell, and the positioning portion is embedded in the positioning hole, which facilitates the positioning between the connecting piece and the cover plate, prevents the connecting piece from tilting and shifting, and improves the assembly efficiency; at the same time, the ratio between the size of the positioning portion in the first direction and the maximum size of the positioning portion in the second direction is limited, thereby improving the energy density of the secondary battery while improving the current carrying capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0020] Figure 1 It is a structural schematic diagram of a connecting piece provided in an embodiment of the present application.

[0021] Figure 2 yes Figure 1 Bottom view of the .

[0022] Figure 3 It is a cross-sectional view of a top cover assembly provided in an embodiment of the present application.

[0023] Figure 4 It is a schematic diagram of the structure of another connecting piece provided in an embodiment of the present application.

[0024] Figure 5 yes Figure 4 Bottom view of the .

[0025] Figure 6 It is a schematic diagram of a slot structure provided in an embodiment of the present application.

[0026] Figure 7 It is a schematic diagram of another groove structure provided in an embodiment of the present application.

[0027] Figure 8 It is a schematic diagram of another groove structure provided in an embodiment of the present application.

[0028] Fig. 9 It is a schematic structural diagram of a secondary battery provided in an embodiment of the present application.

[0029] Fig.10 This is a schematic diagram of the battery cell installation provided in an embodiment of the present application.

[0030] Fig.11 It is a cross-sectional view of another top cover assembly provided in an embodiment of the present application.

[0031] Fig.12 It is a schematic diagram of an anti-short circuit portion provided in an embodiment of the present application.

[0032] Fig.13 It is a schematic diagram of another anti-short circuit portion provided in an embodiment of the present application.

[0033] In the figure:

[0034] 10. Shell;

[0035] 20. Battery cell; 21. Tab;

[0036] 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. Avoiding 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. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0038] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] In order to solve the technical problems of low space utilization and low energy density of secondary batteries in the prior art, an embodiment of the present application provides a secondary battery. The secondary battery 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 part, a positioning part and a second connecting part, the positioning part is convexly arranged on the first connecting part, the first connecting part is electrically connected to the battery cell, the positioning part is embedded in the positioning hole, the second connecting part is located at the end of the positioning part away from the first connecting part, and the second connecting part is electrically connected to the pole structure, the size of the positioning part in the first direction is Amm, and the maximum size of the positioning part in the second direction is Φmm, which satisfies: 0.1≤A / Φ≤2. The following is a detailed description.

[0040] See also Figure 2 and Fig. 9 In one embodiment, the secondary batteries have first directions perpendicular to each other (eg Figure 2 The middle direction Z, the same below) and the second direction (as Figure 2 As shown in the direction X, the same below), 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 pole ear 21.

[0041] See also Figure 1 , Figure 2 , Figure 3 , Fig.10In some embodiments, the top cover assembly 30 includes a cover plate 31, a pole structure 32 and a connecting piece 33, wherein the pole structure 32 is disposed on the cover plate 31, one end of the connecting piece 33 is electrically connected to the pole ear 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, and the connecting piece 33 includes a first connecting portion 331, a positioning portion 332 and a second connecting portion 333, wherein the positioning portion 332 is protruding from the first connecting portion The second connection portion 333 is located at the end of the positioning portion 332 away from the first connection portion 331, that is, the first connection portion 331 and the second connection portion 333 are spaced apart in the first direction, which increases the space utilization rate of the battery cell 20 and further improves the energy density of the secondary battery. The positioning portion 332 is convexly arranged to facilitate the positioning between the connecting piece 33 and the cover plate 31, prevent the connecting piece 33 from tilting and shifting, and improve the assembly efficiency.

[0042] It should be noted that the first connection portion 331 is provided with a through hole, one end of the positioning portion 332 is connected to the edge of the first connection portion 331 provided with 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 to form the positioning portion 332 and the second connection portion 333. The first connection portion 331 is electrically connected to the pole lug 21, and the second connection portion 333 is electrically connected to the pole column structure 32 (such as Fig.10 As shown, Fig.10 3 is a schematic diagram of the installation of the battery cell provided in the embodiment of the present application. In this embodiment, laser welding is used for connection. In other embodiments, ultrasonic welding or resistance welding and other connection methods may also be used, but are not limited thereto. In the actual production process, the pole ear 21 is first welded to the first connecting portion 331. After the pole ear 21 is connected, the second connecting portion 333 is positioned in the positioning hole 321 through the positioning portion 332, and the second connecting portion 333 is welded to the pole structure 32. In some embodiments, the first connecting portion 331 is provided with an avoidance groove 3311, and the cover plate 31 is provided with a liquid injection port. The orthographic projection of the avoidance groove 3311 on the cover plate 31 covers the liquid injection port. This setting can facilitate liquid injection and reduce the material of the connecting piece 33, thereby realizing the lightweight of the connecting piece 33. Of course, in other embodiments, the avoidance groove 3311 may not be provided, and the first connecting portion 331 may be turned 180° to avoid the liquid injection port. There are other forms of settings, which will not be repeated here.

[0043] Please continue reading Figure 1In 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 at 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. Such a configuration further realizes the lightweight of the connecting piece 33.

[0044] Please continue reading Figure 2 In one embodiment, by cross-cutting the positioning portion 332 perpendicularly to the first direction, a circular cross-section can be obtained, and along the direction from the first connection portion 331 to the second connection portion 333, the cross-sectional area of ​​the above-mentioned positioning portion 332 gradually decreases (that is, the cross-sectional area obtained by cross-cutting the positioning portion 332 near the first connection portion 331 is larger than the cross-sectional area obtained by cross-cutting the positioning portion 332 near the second connection portion 333), and the above-mentioned positioning portion 332 has an outer wall, and the angle between the outer wall and the above-mentioned first direction is α, and the range of α is 0°~30°. For example, when the positioning portion 332 is in the 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 side wall of the positioning portion 332 is the side surface of the truncated cone structure, and the cross section obtained by cross-cutting the positioning portion 332 perpendicular to the first direction is a circular cross section. When the cross section obtained by cross-cutting the positioning portion 332 perpendicular to the first direction is a hexagonal structure, the positioning portion 332 has a total of six outer side walls, and the distance between each outer side wall of the positioning portion 332 and the central axis of the hexagonal structure gradually decreases from the first connecting portion 331 to the second connecting portion 333. In this embodiment, an example is given in which the positioning portion 332 is in the side shape of a truncated cone structure at 30°. 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°. The setting of the angle α facilitates the nesting cooperation between the positioning portion 332 and the positioning hole 321.

[0045] It should be noted that the above-mentioned cross-section is a plane perpendicular to the above-mentioned first direction. In addition, in some embodiments, due to manufacturing differences, the cross-sectional areas of two particularly close points are not necessarily reduced in fact, and are gradually reduced 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 section of the central axis of the positioning portion 332, and then measure the angle through 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.

[0046] See also Figure 4 and Figure 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 arranged at an angle, and the inner side surface of the positioning hole 321 includes at least two second wall surfaces 3211 (such as Fig.11 As shown, Fig.11 3211 is a cross-sectional view of another top cover assembly provided in an embodiment of the present application, wherein the second walls 3211 are also adjacent to each other and are arranged at an angle, and when the positioning portion 332 is embedded in the positioning hole 321, the first wall 3321 and the second wall 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; in the present embodiment, six first walls 3321 are provided, i.e., the cross section of the positioning portion 332 is hexagonal, and six second walls 3211 are also provided on the inner side surface of the corresponding positioning hole 321, and other embodiments may be pentagonal or other shapes, but are not limited thereto, and through the arrangement of the first wall 3321 and the second wall 3211, the connection piece 33 can be prevented from twisting, and when the positioning portion 332 is embedded in the positioning hole 321 during welding installation, the position of the connection piece 33 is fixed, thereby ensuring the welding quality and efficiency, and improving the assembly efficiency.

[0047] Please continue reading 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.

[0048] Furthermore, in the present embodiment, the pole body 323 includes a main body 3232, a first fixing portion 3231 and a second fixing portion 3233. The main body 3232 is passed through the connecting hole 311. The first fixing portion 3231 and the second fixing portion 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 portion 3231 and the second fixing portion 3233 to fix the pole body 323 on the cover plate 31. In the present embodiment, the positioning hole 321 is arranged on the main body 3232, and the positioning hole 321 is a blind hole.

[0049] It should be noted that the pole body 323 is fixed in the connection hole 311 on the cover plate 31 through 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 here; the positioning hole 321 is a blind hole, that is, the second connecting portion 333 abuts against the bottom of the positioning hole 321 and is welded thereto. In other embodiments, the pole body 323 and the positioning hole 321 can also be arranged in other forms, such as Fig.11 In the illustrated embodiment, 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 plate 33, and the second connecting portion 333 passes through the positioning hole 321 and abuts against the pole body 323, and a welding operation is performed. The present invention is not limited to this, and other forms of settings may also be used, which will not be described in detail here.

[0050] See also Fig.12 In one embodiment, the first connecting portion 331 further includes an anti-short circuit portion 3314, which is disposed 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, and the 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 the 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 the battery. The connecting piece 33 has a third direction (such as Fig.12 The anti-short-circuit portion 3314 extends in a strip shape along the third direction. In the present 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 to cause it to fuse, thereby ensuring the safety of the battery.

[0051] 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 fused when a battery short circuit occurs, and the strip-shaped arrangement can reduce the lateral ( Fig.12 The size of the short circuit prevention portion 3314 is conducive to a compact structure; in other embodiments, the short circuit prevention portion 3314 can also be arranged in other forms, such as Fig.13In the embodiment shown, 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. When a short circuit occurs, the temperature of the connecting piece 33 rises, and the anti-short circuit portion 3314 melts before the first sub-portion 3312 and the second sub-portion 3313, thereby ensuring the safety of the battery.

[0052] See also Figure 6-8 A groove structure 3331 is provided on the side where the second connecting portion 333 abuts against the pole structure 32, that is, a groove structure 3331 is provided on the surface where the second connecting portion 333 is welded to the pole body 323. The groove opening of the groove structure 3331 is provided on the surface of the second connecting portion 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.

[0053] It should be noted that the entire connecting piece 33 can also be formed by stamping, which will not be described in detail here.

[0054] In some embodiments, the size of the positioning portion 332 in the first direction is A mm, 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, 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 carrying 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.

[0055] The following structural specific embodiments are used to evaluate the performance of the technical solutions provided in the embodiments of the present application.

[0056] 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 500Wh / mm 3 The flow capacity is reflected by the maximum flow area S. The larger S is, the better the flow capacity is. However, in order to meet the charge and discharge rate requirements of the secondary battery and make the secondary battery practical, the minimum flow area is 20mm 2 The specific parameters and test results are shown in Table 1.

[0057] Table 1

[0058]

[0059] It should be noted that T=500*[100 / (100-A)], S=π*(Φ / 2)2; It can be seen from Examples 1-8 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 embodiments can improve the space utilization while ensuring the energy density and current capacity of the battery; On the other hand, in Comparative Example 1, A / Φ=0.09, at this time, the Φ value is too large, the space of the battery cover 31 is insufficient, and the connecting piece 33 is close to the edge of the cover 31 or the shell 10, which affects the design of the edge plastic part and the welding of the cover 31. To make the value of A / Φ smaller, A needs to be smaller and / or Φ needs to be larger, and the Φ value does not meet the use requirements; In Comparative Example 2, A / Φ=2.5, at this time, the Φ value is too small, and S is less than 20mm 2 , which cannot meet the requirements for the use of the battery flow area. To increase the value of A / Φ, A needs to become larger and / or Φ needs to become smaller. The Φ value does not meet the requirements for the use of the flow area.

[0060] On the other hand, the secondary battery in any one of the above embodiments may be used in a battery pack, which further includes a box, and the secondary battery is accommodated in the box.

[0061] 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 idea. At the same time, for those skilled in the art, according to the idea of ​​the present application, there will 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, characterized in that: The secondary battery has a first direction (Z) and a second direction (X) which are perpendicular to each other, and comprises a shell (10), a battery cell (20) and a top cover assembly (30), wherein the shell (10) and the top cover assembly (30) cooperate to enclose a closed space, and the battery cell (20) is 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 size of the positioning portion (332) in the first direction (Z) is A mm; the maximum size 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° to 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, characterized in that: 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 passed 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) 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, characterized in that: 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) and is 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, the first connecting portion (331) is provided with an avoidance groove (3311), and 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 on 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, characterized in that The first connecting portion (331) further comprises an anti-short circuit portion (3314), the anti-short circuit portion (3314) being connected between the first sub-portion (3312) and the second sub-portion (3313), the connecting piece (33) having a third direction (Y), the anti-short circuit portion (3314) extending along the third direction (Y); and / or, A groove structure (3331) is provided on one side of the second connecting portion (333) abutting against the pole structure (32).

11. A battery pack, characterized in that: The battery pack comprises the secondary battery as claimed in any one of claims 1 to 10, wherein the battery pack further comprises a box, and the secondary battery is accommodated in the box.

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