Battery cell and battery pack

Abstract

Disclosed in the present application are a battery cell and a battery pack. The battery cell comprises a casing, a top cover assembly and an electrode assembly, wherein the casing is provided with an accommodating cavity, which has an opening; the electrode assembly is arranged in the accommodating cavity; the top cover assembly seals the opening in a covering manner, and comprises a first top cover and a second top cover; the electrode assembly comprises an electrode assembly body and a tab connected to the electrode assembly body, the tab being electrically connected to the second top cover; a connecting hole penetrating in the thickness direction of the first top cover is provided in the first top cover; part of the second top cover is accommodated in the connecting hole, and the second top cover is connected to a hole wall of the connecting hole; and the ratio of the cross-sectional area of the connecting hole to the surface area of one side of the first top cover is α, and α satisfies 0.01≤α≤0.36.

Description

Battery cells and battery packs

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 11, 2023, with application number 202322469380.0 and patent name “Battery Cell and Battery Pack”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the field of battery manufacturing technology, and specifically relates to a battery cell and a battery pack. Background Art

[0003] In the prior art, when assembling a battery cell, since the battery cell has only one top cover and a large area, it is necessary to first connect the electrode assembly to the connecting piece outside the shell cavity, then weld the connecting piece and the top cover, and then flip the electrode assembly over and close the core before placing the electrode assembly into the shell cavity. This assembly method is quite difficult.

[0004] Summary of the Invention

[0005] The purpose of the embodiments of the present application is to provide a battery cell and a battery pack to solve or at least partially solve the problem in the prior art that when assembling a battery cell, the battery cell top cover is difficult to assemble.

[0006] In order to solve the above technical problems, this application is implemented as follows:

[0007] In the first aspect, an embodiment of the present application provides a battery cell, which includes a shell, a top cover assembly and an electrode assembly, the shell having a accommodating cavity with an opening, the electrode assembly being arranged in the accommodating cavity, the top cover assembly covering the opening, the top cover assembly including a first top cover and a second top cover, the electrode assembly including an electrode assembly body and a pole ear connected to the electrode assembly body, the pole ear being electrically connected to the second top cover; a connecting hole is provided on the first top cover, which passes through the first top cover in a thickness direction, the second top cover is partially accommodated in the connecting hole, and the second top cover is connected to the hole wall of the connecting hole; wherein, the ratio of the cross-sectional area of ​​the connecting hole to the surface area of ​​one side of the first top cover is α, wherein α satisfies: 0.01≤α≤0.36.

[0008] Optionally, the second top cover includes a second top cover plate and a pole, the second top cover plate is provided with a through hole penetrating the second top cover plate along the thickness direction, the pole is passed through the through hole, the pole and the pole ear are electrically connected, the second top cover plate is accommodated in the connecting hole, and the second top cover plate is connected to the hole wall of the connecting hole.

[0009] Optionally, there are two connecting holes, which are spaced apart along the length direction of the first top cover, and there are two second top covers, which are respectively arranged corresponding to the two connecting holes, one second top cover is at least partially accommodated in one connecting hole, and one second top cover is connected to the hole wall of one connecting hole, and the electrode tabs include positive electrode tabs and negative electrode tabs spaced apart along the length direction of the first top cover, the positive electrode tab is connected to one of the second top covers, and the negative electrode tab is connected to the other second top cover.

[0010] Optionally, the outer edge of the second top cover is connected to the hole wall of the connecting hole by welding.

[0011] Optionally, the outer edge of the second top cover is connected to the hole wall of the connecting hole by ultrasonic welding; or, the outer edge of the second top cover is connected to the hole wall of the connecting hole by laser welding.

[0012] Optionally, the connecting hole is a stepped hole, which includes a countersunk hole portion and a through hole portion that are interconnected, and the outer edge of the second top cover has a step structure that cooperates with the stepped hole, and the step structure includes a first connecting portion and a second connecting portion that are interconnected, and on the plane where the second top cover is located, the projection of the second connecting portion is located inside the projection of the first connecting portion; the countersunk hole portion is connected to the first connecting portion, or the through hole portion is connected to the second connecting portion.

[0013] Optionally, a connection point between the first connection portion and the second connection portion is an arc structure, and / or a connection point between the countersunk hole portion and the through hole portion is an arc structure.

[0014] Optionally, a connection point between the first connection portion and the second connection portion is a sloped surface, and a connection point between the countersunk hole portion and the through hole portion is a sloped surface, wherein the sloped surface is inclined relative to a hole wall of the through hole portion.

[0015] Optionally, the height of the countersunk hole portion is H1, and the height of the through hole portion is H2, and H1 satisfies: 0.1mm≤H1≤5mm, and H2 satisfies: 0.1mm≤H2≤5mm; wherein, H1 is the dimension of the countersunk hole portion in the thickness direction of the first top cover, and H2 is the dimension of the through hole portion in the thickness direction of the first top cover.

[0016] Optionally, the shape of the connection hole is rectangular or the shape of the connection hole is circular.

[0017] In a second aspect, an embodiment of the present application further provides a battery pack, comprising: a battery cell as described in any one of the above-mentioned first aspects.

[0018] In an embodiment of the present application, a battery cell includes a housing, a top cover assembly, and an electrode assembly, wherein the housing defines a housing cavity with an opening, wherein the electrode assembly can be positioned within the housing cavity, and the top cover assembly seals the opening, thereby enabling the top cover assembly to seal the electrode assembly. The top cover assembly includes a first top cover and a second top cover, wherein the second top cover is electrically connected to the electrode tab of the electrode assembly. Since the first top cover is provided with a connection hole extending through the thickness of the first top cover, and the position of the connection hole corresponds to the position of the second top cover, the second top cover can be positioned within the communication hole, and the edge of the second top cover is connected to the hole wall of the communication hole to achieve connection between the second top cover and the first top cover, so that the top cover assembly can seal the opening and connect to the electrode of the electrode assembly. Since the top cover assembly includes the first top cover and the second top cover, when assembling the electrode assembly to form a battery cell, the electrode assembly can be placed in the housing cavity first. When welding the electrodes, the electrode tab and the second top cover can be welded first. After the second top cover and the electrode tab are welded, the first top cover can be placed in the opening, and the second top cover can be connected to the communication hole to complete the assembly of the battery cell. This setting method can be carried out after the electrode assembly is placed in the accommodating cavity. The electrode and the second top cover can be directly welded, and then the second top cover and the first top cover are connected. This avoids the problem of folding and closing the winding core in the electrode assembly when the top cover assembly is a whole. It can reduce the size of the pole ear and reduce the difficulty of assembly.

[0019] At the same time, in the embodiment of the present application, the ratio of the area of ​​the connection hole to the total area of ​​the first top cover is α. Since α satisfies: 0.01≤α≤0.36, the overcurrent of the battery cell can be guaranteed, and the connection strength between the first top cover and the second top cover can be guaranteed.

[0020] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] FIG1 is a schematic diagram of the structure of a battery cell according to an embodiment of the present application;

[0023] FIG2 is a second structural schematic diagram of a battery cell provided in an embodiment of the present application;

[0024] FIG3 is a top view of a battery cell according to an embodiment of the present application;

[0025] FIG4 is a second top view of a battery cell provided in an embodiment of the present application;

[0026] FIG5 is a schematic diagram showing the connection between the first top cover and the second top cover according to an embodiment of the present application;

[0027] FIG6 is a second schematic diagram of the connection between the first top cover and the second top cover provided in an embodiment of the present application;

[0028] FIG7 is a cross-sectional view of a battery cell provided in an embodiment of the present application;

[0029] FIG8 is one of the partial enlarged views of point A in FIG7 ;

[0030] FIG9 is a second partial enlarged view of point A in FIG7 .

[0031] Reference numerals: 100: battery cell; 10: top cover assembly; 11: first top cover; 111: connection hole; 112: stepped hole; 1121: countersunk hole portion; 1122: through-hole portion; 12: second top cover; 121: second top cover plate; 1211: through-hole; 122: electrode column; 123: stepped structure; 1231: first connecting portion; 1232: second connecting portion; 13: arc structure; 14: inclined surface; 15: accommodating cavity; 20: electrode assembly; 21: electrode assembly body; 22: electrode tab; 30: housing; Specific embodiments

[0032] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0033] As shown in Figures 1 to 9, the battery cell 100 includes a shell 30, a top cover assembly 10 and an electrode assembly 20. The shell 30 is provided with a accommodating cavity 15, and the electrode assembly 20 is arranged in the accommodating cavity 15. The shell 30 has an opening connecting the outside and the accommodating cavity 15, and the top cover assembly 10 covers the opening. The top cover assembly 10 includes a first top cover 11 and a second top cover 12. The electrode assembly 20 includes an electrode assembly body 21 and a tab 22 connected to the electrode assembly body 21, and the tab 22 is electrically connected to the second top cover 12; a connecting hole 111 is provided on the first top cover 11, which passes through the first top cover 11 in the thickness direction, and the second top cover 12 is partially accommodated in the connecting hole 111, and the edge of the second top cover 12 is connected to the hole wall of the connecting hole 111; wherein, the ratio of the cross-sectional area of ​​the connecting hole 111 to the surface area of ​​one side of the first top cover 11 is α, wherein α satisfies: 0.01≤α≤0.36.

[0034] In the embodiment of the present application, the battery cell 100 includes a shell 30, a top cover assembly 10, and an electrode assembly 20. The shell 30 is provided with a receiving cavity 15 having an opening, and the electrode assembly 20 can be placed in the receiving cavity 15. The top cover assembly 10 covers the opening, so that the electrode assembly 20 can be sealed by the top cover assembly 10. The top cover assembly 10 includes a first top cover 11 and a second top cover 12. The second top cover 12 is electrically connected to the tab 22 of the electrode assembly 20. Since the first top cover 11 is provided with a connecting hole 111 that passes through the thickness direction of the first top cover 11, and the position of the connecting hole 111 corresponds to the position of the second top cover 12, the second top cover 12 can be placed in the connecting hole, and the edge of the second top cover 12 is connected to the hole wall of the connecting hole to realize the connection between the second top cover 12 and the first top cover 11, so that the top cover assembly 10 can cover the opening and connect to the tab 22 of the electrode assembly 20.

[0035] In the embodiment of the present application, since the top cover assembly 10 includes the first top cover 11 and the second top cover 12, when assembling the battery cell 100, the electrode assembly 20 can be first placed in the accommodating cavity 15, and the electrode tab 22 can be welded to the second top cover 12 first. After the welding of the second top cover 12 to the electrode tab 22 is completed, the first top cover 11 can be placed in the opening, and the second top cover 12 can be connected to the communication hole to complete the assembly of the battery cell 100. This arrangement can be performed after the electrode assembly 20 is placed in the accommodating cavity 15, and the electrode assembly and the second top cover 12 can be directly welded, and then the second top cover 12 can be connected to the first top cover 11. This avoids the problem of folding and closing the winding core in the electrode assembly 20 when the top cover assembly 10 is a whole unit, thereby reducing the difficulty of assembly.

[0036] The ratio of the cross-sectional area of ​​the connection hole 111 to the surface area of ​​one side of the first cover 11 is α, and since α satisfies: 0.01≤α≤0.36, this can ensure the overcurrent of the battery cell 100 and enhance the welding strength between the first cover 11 and the second cover 12.

[0037] It should be noted that in the battery cell provided in the present application, since the top cover assembly 10 includes two parts, the first top cover 11 and the second top cover 12, that is, the top cover assembly 10 is arranged separately, the electrode assembly 20 can be directly placed in the accommodating cavity 15 as a whole, and then the top cover assembly 10 is welded by welding the second top cover 12 and the first top cover 11. In the related art, since the core needs to be folded and closed, in order to ensure that the core closing process can proceed normally, the thickness of the electrode assembly needs to be smaller, and the thickness of the resulting battery cell 100 is also smaller. However, since the present application does not require core closing, it can avoid the situation where the top cover assembly 10 is limited by the thickness of the electrode assembly 20 when welding. Therefore, the solution of the present application of setting the top cover assembly 10 separately can make the thickness of the battery cell 100 larger. The present application proposes that the thickness of the battery cell 100 can be greater than or equal to 50 mm.

[0038] It should also be noted that α satisfies: 0.01≤α≤0.36. Specifically, α can be 0.01, 0.02, 0.28, 0.3, 0.35, 0.036, etc.

[0039] Further provided are some embodiments and comparative examples of the present application, wherein the cross-sectional area of ​​the connection hole 111 refers to the opening area of ​​the connection hole. The area of ​​the connection hole 111 projected in the thickness direction of the first top cover can be determined by measuring the area of ​​the projection pattern using an image measuring instrument to serve as the cross-sectional area of ​​the connection hole. The surface area of ​​one side of the first top cover 11 refers to the projection area of ​​the surface of the first top cover away from the assembly in the thickness direction of the first top cover. The surface area of ​​the projection pattern can be determined by measuring the area of ​​the projection pattern using an image measuring instrument to serve as the surface area of ​​one side of the first top cover 11. The compressive strength of the weld can be tested by inflating the interior of the battery cell with air using a pneumatic loading tester. During the test, the large surface of the battery cell is fixed and tightened with a fixture until the battery cell weld cracks and leaks. The critical air pressure value for air leakage is the compressive strength. The battery cell can be charged multiple times with different currents. The battery cell temperature and charging time are the same before each charge. The maximum charging current when the battery cell temperature does not exceed 55°C is measured. This current is the battery cell overcurrent.

[0040] According to the above table, when α satisfies: 0.01≤α≤0.36, the weld compressive strength and the overcurrent of the battery cell can be ensured to be good, and the overall performance of the battery cell is better.

[0041] In addition, in some embodiments, as shown in Figure 7, the second top cover 12 may include a second top cover plate 121 and a pole 122. The second top cover plate 121 is provided with a through hole 1211 that penetrates the second top cover plate 121 along the thickness direction. The pole 122 is passed through the through hole 1211, and the pole 122 is electrically connected to the pole ear 22.

[0042] The second top cover 12 includes a second top cover plate 121 and a pole 122. The second top cover plate 121 is received in the connection hole 111 and connected to the hole wall of the connection hole 111. The second top cover plate 121 is provided with a through hole 1211 that penetrates the second top cover plate 121 along the thickness direction. The pole 122 is provided in the through hole 1211 and is provided on the second top cover plate 121. The pole 122 can be electrically connected to the tab 22 to achieve electrical connection between the second top cover 12 and the tab 22. That is, in the embodiment of the present application, the second top cover 12 includes the pole 122, and the second top cover 12 can be connected to the tab 22 of the electrode assembly 20 through the pole 122, so that the top cover assembly 10 can be electrically connected to the tab 22, thereby achieving electrical conduction between the electrode assembly 20 and the outside.

[0043] In addition, in some embodiments, as shown in Figures 1 to 4, there can be two connection holes 111, and the two connection holes 111 are spaced apart along the length direction of the first top cover 11. There are two second top covers 12, and the two second top covers 12 are respectively arranged corresponding to the two connection holes 111. The tabs 22 include positive tabs and negative tabs spaced apart along the length direction of the first top cover 11, the positive tab is connected to one of the second top covers 12, and the negative tab is connected to the other second top cover 12.

[0044] Two connection holes 111 are provided on the first top cover 11, and the two connection holes 111 are spaced apart along the length of the first top cover 11. Two second top covers 12 are also provided, and the two second top covers 12 are also spaced apart along the length of the first top cover 11, so that the two second top covers 12 can be respectively provided with two connection holes 111, so that the two second top covers 12 can be respectively placed in the two communicating holes, and the edges of the second top covers 12 are connected to the hole walls of the connection holes 111. Since the tabs 22 of the electrode assembly 20 include positive tabs and negative tabs spaced apart along the length of the first top cover 11, the positive tab can be connected to one of the second top covers 12, and the negative tab can be connected to the other second top cover 12, so that both tabs can be connected to the second top cover 12. Then, the two second top covers 12 and the two connection holes 111 are connected, so that the positive and negative electrodes of the electrode assembly 20 can be connected to the top cover assembly 10, thereby achieving electrical conductivity between the electrode assembly 20 and the outside.

[0045] In addition, in some embodiments, the outer edge of the second top cover 12 may be connected to the hole wall of the connecting hole 111 by welding.

[0046] The second top cover 12 is disposed in the connection hole 111, and the outer edge of the second top cover 12 faces the hole wall of the connection hole 111, so that the second top cover 12 and the first top cover 11 can be connected by connecting the outer edge of the second top cover 12 to the hole wall of the connection hole 111. The outer edge of the second top cover 12 and the hole wall of the connection hole 111 can be connected by welding, which can make the connection between the second top cover 12 and the connection hole 111 more reliable.

[0047] It should be noted that when welding the outer edge of the second top cover 12 to the wall of the connecting hole 111, the connection can be made by ultrasonic welding, or by laser welding. Laser welding connects the second top cover 12 and the connecting hole 111 through the high temperature of the laser beam, which can avoid deformation, oxidation and other problems caused by traditional welding methods. Of course, other welding methods can also be used. The specific welding method between the second top cover 12 and the connecting hole 111 is not specifically limited in the embodiment of the present application.

[0048] In addition, in some embodiments, as shown in Figures 5 to 9, the connecting hole 111 can be a stepped hole 112, the stepped hole 112 includes a countersunk hole portion 1121 and a through hole portion 1122 that are interconnected, and the outer edge of the second top cover 12 has a step structure 123 that cooperates with the stepped hole 112, the step structure 123 includes a first connecting portion 1231 and a second connecting portion 1232 that are interconnected, and on the plane where the second top cover 12 is located, the projection of the second connecting portion 1232 is located inside the projection of the first connecting portion 1231; the countersunk hole portion 1121 is connected to the first connecting portion 1231, or the through hole portion 1122 is connected to the second connecting portion 1232.

[0049] The connection hole 111 is a stepped hole 112. Accordingly, in order to allow the outer edge of the second top cover 12 to correspond to the stepped hole 112-shaped connection hole 111, the outer edge of the second top cover 12 may have a stepped structure 123 that cooperates with the stepped hole 112, so that the stepped structure 123 can be connected to the stepped hole 112 to achieve the connection between the second top cover 12 and the first top cover 11. The provision of the stepped hole 112 can serve as a guide, positioning, and limiting function for the installation of the stepped structure 123, making it easier to place the second top cover 12 in the connection hole 111.

[0050] Specifically, the step structure 123 includes a first connection part 1231 and a second connection part 1232 which are connected to each other. Since the projection of the second connection part 1232 is located inside the projection of the first connection part 1231 on the plane where the second top cover 12 is located, the size of the second connection part 1232 is smaller, and the first connection part 1231 can extend outward from the edge of the second connection part 1232, so that the size of the first connection part 1231 is larger. The step hole 112 includes a countersunk hole portion 1121 and a through hole portion 1122 that are interconnected. The through hole portion 1122 can penetrate the first top cover 11 along the thickness direction of the first top cover 11, while the countersunk hole portion 1121 extends along the thickness direction of the first top cover 11, but does not penetrate the first top cover 11. Since the countersunk hole portion 1121 and the through hole portion 1122 are interconnected, it is equivalent to that the through hole portion 1122 is set at the bottom of the countersunk hole portion 1121. The size of the countersunk hole portion 1121 is larger than the size of the through hole portion 1122, so that the size of the position where the countersunk hole portion 1121 is set on the first top cover 11 is smaller, and the size of the position where the through hole is set on the first top cover 11 is relatively larger. During connection, the larger position on the outer edge of the second top cover 12 can be connected to the smaller position on the first top cover 11, or the smaller position on the outer edge of the second top cover 12 can be connected to the larger position on the first top cover 11, that is, the countersunk hole portion 1121 can be connected to the first connecting portion 1231, or the through hole portion 1122 can be connected to the second connecting portion 1232, so as to achieve a tight connection between the two.

[0051] It should be noted that when connecting the step hole 112 and the step structure 123, only the portion away from the electrode structure can be connected. Specifically, as shown in FIG5 , when the countersunk hole portion 1121 is arranged close to the interior of the shell 30, the through-hole portion 1122 can be connected to the second connection portion 1232. At this time, the countersunk hole portion 1121 can be disconnected from the first connection portion 1231, which can prevent welding slag from falling through the countersunk hole portion 1121 and the first connection portion 1231 when welding. As shown in FIG6 , when the countersunk portion 1121 is positioned away from the interior of the housing 30, the countersunk portion 1121 can be connected to the first connecting portion 1231. In this case, the through-hole portion 1122 can be disconnected from the second connecting portion 1232. This can prevent welding slag from passing through the through-hole portion 1122 and the second connecting portion 1232 and falling into the electrode assembly 20 during welding, burning through the winding core and causing a short circuit in the electrode assembly 20. Furthermore, when the countersunk portion 1121 is positioned away from the interior of the housing 30, the through-hole portion 1122 can also block the second top cover 12 when connecting the second top cover 12 to the first top cover 11, preventing the second top cover 12 from falling through the connecting hole 111 into the interior of the housing 30.

[0052] In addition, in some embodiments, as shown in FIG8 , the connection between the first connection portion 1231 and the second connection portion 1232 may be an arc structure, and / or the connection between the countersunk hole portion 1121 and the through hole portion 1122 may be an arc structure.

[0053] The connection between the first connection part 1231 and the second connection part 1232 is an arc structure, and / or the connection between the countersunk hole part 1121 and the through hole part 1122 is an arc structure, that is, the connection between the first connection part 1231 and the second connection part 1232 can be rounded so that the first connection part 1231 and the second connection part 1232 can transition through an arc, and the connection between the countersunk hole part 1121 and the through hole part 1122 can also be rounded so that the countersunk hole part 1121 and the through hole part 1122 can transition through an arc, which can facilitate the assembly of the first top cover 11 and the second top cover 12, and the connection position of the second top cover 12 and the connecting hole can be in close contact, thereby improving the welding quality of the second top cover 12 and the connecting hole.

[0054] In addition, in some embodiments, as shown in Figure 9, the connection between the first connection part 1231 and the second connection part 1232 can be a slope 14, and the connection between the countersunk hole part 1121 and the through hole part 1122 is a slope 14, wherein the slope 14 is inclined relative to the hole wall of the through hole part 1122.

[0055] The connection between the first connection part 1231 and the second connection part 1232 is a bevel 14, and / or the connection between the countersunk hole part 1121 and the through hole part 1122 is a bevel 14, that is, the connection between the first connection part 1231 and the second connection part 1232 can be beveled, so that the first connection part 1231 and the second connection part 1232 can transition through the bevel 14, and the connection between the countersunk hole part 1121 and the through hole part 1122 can also be beveled, so that the countersunk hole part 1121 and the through hole part 1122 can transition through the bevel 14, which can facilitate the assembly of the first top cover 11 and the second top cover 12, and the connection position of the second top cover 12 and the connecting hole can be in close contact, thereby improving the welding quality of the second top cover 12 and the connecting hole.

[0056] In addition, in some embodiments, the height of the countersunk hole portion 1121 is H1, and the height of the through hole portion 1122 is H2, H1 can satisfy: 0.1mm≤H1≤5mm, and H2 can satisfy: 0.1mm≤H2≤5mm; wherein H1 is the dimension of the countersunk hole portion 1121 in the thickness direction of the first top cover 11, and H2 is the dimension of the through hole portion 1122 in the thickness direction of the first top cover 11.

[0057] The height of the countersunk hole portion 1121 is H1, and the height of the through-hole portion 1122 is H2. H1 satisfies: 0.1mm≤H1≤5mm, and H2 satisfies: 0.1mm≤H2≤5mm. The countersunk hole portion 1121 or the through-hole portion 1122 is directly connected to the outer edge of the second top cover 12. The thickness of the countersunk hole portion 1121 and the thickness of the through-hole portion 1122 directly affect the fit between the second top cover 12 and the first top cover 11, and thus affect the position of the pole 122 in the first top cover 11. When the height of the countersunk hole portion 1121 and the height of the through-hole portion 1122 meet the above ranges, on the one hand, it is convenient for the subsequent welding and cover-closing process of the battery cell 100. On the other hand, it can facilitate the welding of the second top cover 12 and the first top cover 11, ensure the welding quality of the second top cover 12 and the first top cover 11, and avoid the problem of the first top cover 11 or the second top cover 12 being burned through due to the welding position being too thin.

[0058] Among them, H1 is the dimension of the countersunk hole portion 1121 in the thickness direction of the first top cover 11, and H2 is the dimension of the through hole portion 1122 in the thickness direction of the first top cover 11, as shown in Figure 8, which shows the height of the countersunk hole portion 1121 and the height of the through hole portion 1122.

[0059] It should be noted that the height of the countersunk portion 1121 can be specifically 0.1 mm, 0.2 mm, 0.28 mm, 2 mm, 5 mm, etc., and the height of the through-hole portion 1122 can be specifically 0.1 mm, 0.2 mm, 0.28 mm, 2 mm, 5 mm, etc. The specific values ​​of the height of the countersunk portion 1121 and the height of the through-hole portion 1122 are not specifically limited in this embodiment of the application. Correspondingly, the heights of the first connecting portion 1231 and the second connecting portion 1232 can be set according to the heights of the countersunk portion 1121 and the through-hole portion 1122. The height of the countersunk portion 1121 and the height of the through-hole portion 1122 can be the same, or the height of the countersunk portion 1121 and the height of the through-hole portion 1122 can be different. This is not specifically limited in this embodiment of the application. The height of the countersunk portion 1121 and the height of the through-hole portion 1122 can be measured using a vernier caliper or a micrometer.

[0060] In addition, in some embodiments, the shape of the connection hole 111 may be rectangular or the shape of the connection hole 111 may be circular.

[0061] The connection hole 111 is rectangular or circular in shape, and the corresponding outer edge of the second top cover 12 can also be rectangular or circular to ensure that the second top cover 12 fits the first top cover 11. Both rectangular and circular shapes are relatively regular, simplifying the welding path when connecting the second top cover 12 and facilitating control of the welding machine to weld the hole wall of the connecting hole and the outer edge of the second top cover 12, thereby improving welding quality. Figures 1 to 4 illustrate the case where the connection hole 111 is rectangular in shape.

[0062] In the embodiment of the present application, the battery cell 100 includes a shell 30, a top cover assembly 10, and an electrode assembly 20, wherein the shell 30 is provided with a receiving cavity 15 having an opening, and the electrode assembly 20 can be placed in the receiving cavity 15, and the top cover assembly 10 covers the opening, so that the electrode assembly 20 can be sealed by the top cover assembly 10. The top cover assembly 10 includes a first top cover 11 and a second top cover 12, and the second top cover 12 is electrically connected to the tab 22 of the electrode assembly 20. Since the first top cover 11 is provided with a connecting hole 111 that passes through the thickness direction of the first top cover 11, and the position of the connecting hole 111 corresponds to the position of the second top cover 12, the second top cover 12 can be placed in the connecting hole, and the edge of the second top cover 12 is connected to the hole wall of the connecting hole to achieve the connection between the second top cover 12 and the first top cover 11, so that the top cover assembly 10 can cover the opening and connect to the electrode of the electrode assembly 20. Among them, the ratio of the area of ​​the connection hole 111 to the total area of ​​the first top cover 11 is α. Since α satisfies: 0.01≤α≤0.36, on the one hand, it can ensure that the second top cover 12 is reliably connected to the tab 22 and the overcurrent of the battery cell 100 is guaranteed. On the other hand, it can also make the area of ​​the connection hole 111 smaller, reduce the connection cost between the first top cover 11 and the second top cover 12, and improve its connection efficiency.

[0063] That is, in the embodiment of the present application, since the top cover assembly 10 includes the first top cover 11 and the second top cover 12, when assembling the electrode assembly 20 to form the battery cell 100, the electrode assembly 20 can be first placed in the accommodating cavity 15. When welding the electrodes, the electrode tab 22 and the second top cover 12 can be welded first. After the welding of the second top cover 12 and the electrode tab 22 is completed, the first top cover 11 can be placed in the opening, and the second top cover 12 and the communication hole can be connected to complete the assembly of the battery cell 100. This arrangement can be performed after the electrode assembly 20 is placed in the accommodating cavity 15, and the electrode assembly and the second top cover 12 can be directly welded, and then the second top cover 12 and the first top cover 11 can be connected. This avoids the need to fold and core the electrode assembly 20 when the top cover assembly 10 is a whole unit, thereby reducing the difficulty of assembling the battery cell.

[0064] In a second aspect, an embodiment of the present application further provides a battery pack, which includes: the battery cell 100 in any of the above embodiments.

[0065] In the battery cell 100 provided in the above embodiment, since the top cover assembly 10 is separately provided to include the first top cover 11 and the second top cover 12, there is no need to fold or close the electrode assembly 20 when assembling the battery cell 100. This is suitable for battery cells 100 with larger thickness. The thickness of the battery cells 100 in the battery pack provided with the above battery cells 100 can also be larger, thereby increasing the capacity of the battery pack.

[0066] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0067] References herein to "one embodiment," "an embodiment," or "one or more embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Furthermore, please note that instances of the phrase "in one embodiment" do not necessarily all refer to the same embodiment.

[0068] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0069] In the claims, any reference signs placed between brackets shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in the claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present application may be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, wherein: The battery cell comprises a shell, a top cover assembly and an electrode assembly, the shell is provided with a receiving cavity having an opening, the electrode assembly is arranged in the receiving cavity, the top cover assembly covers the opening, the top cover assembly comprises a first top cover and a second top cover, the electrode assembly comprises an electrode assembly body and a pole ear connected to the electrode assembly body, and the pole ear is electrically connected to the second top cover; The first top cover is provided with a connecting hole which penetrates along the thickness direction of the first top cover, the second top cover is partially received in the connecting hole, and the second top cover is connected to the hole wall of the connecting hole; The ratio of the cross-sectional area of ​​the connecting hole to the surface area of ​​one side of the first top cover is α, wherein α satisfies: 0.01≤α≤0.

36.

2. The battery cell according to claim 1, wherein: The second top cover includes a second top cover plate and a pole. The second top cover plate is provided with a through hole penetrating the second top cover plate along the thickness direction. The pole is passed through the through hole. The pole and the pole are electrically connected to the pole ear. The second top cover plate is accommodated in the connecting hole, and the second top cover plate is connected to the hole wall of the connecting hole.

3. The battery cell according to claim 1, wherein: There are two connecting holes, which are spaced apart along the length direction of the first top cover; there are two second top covers, which are respectively arranged corresponding to the two connecting holes; one second top cover is at least partially accommodated in one connecting hole, and one second top cover is connected to the hole wall of one connecting hole; the electrode tabs include a positive electrode tab and a negative electrode tab which are spaced apart along the length direction of the first top cover; the positive electrode tab is connected to one of the second top covers, and the negative electrode tab is connected to the other second top cover.

4. The battery cell according to claim 1, wherein: The outer edge of the second top cover is connected to the hole wall of the connecting hole by welding.

5. The battery cell according to claim 4, wherein: The outer edge of the second top cover is connected to the hole wall of the connecting hole by ultrasonic welding.

6. The battery cell according to claim 1, wherein: The connecting hole is a stepped hole, and the stepped hole includes a countersunk hole portion and a through hole portion that are interconnected. The outer edge of the second top cover has a stepped structure that matches the stepped hole. The stepped structure includes a first connecting portion and a second connecting portion that are interconnected. On the plane where the second top cover is located, the projection of the second connecting portion is located inside the projection of the first connecting portion. The countersunk hole portion is connected to the first connecting portion.

7. The battery cell according to claim 6, wherein: The connection between the first connection portion and the second connection portion is an arc structure.

8. The battery cell according to claim 6, wherein: The connection between the first connection portion and the second connection portion is an inclined surface, and the connection between the countersunk hole portion and the through hole portion is an inclined surface, and the inclined surface is inclined relative to the hole wall of the through hole portion.

9. The battery cell according to claim 6, wherein: The height of the countersunk hole portion is H1, the height of the through hole portion is H2, H1 satisfies: 0.1 mm ≤ H1 ≤ 5 mm, and H2 satisfies: 0.1 mm ≤ H2 ≤ 5 mm; The H1 is a dimension of the countersunk hole portion in the thickness direction of the first top cover, and the H2 is a dimension of the through hole portion in the thickness direction of the first top cover.

10. The battery cell according to any one of claims 1 to 9, wherein: The connection hole is in a rectangular shape.

11. The battery cell according to claim 4, wherein: The outer edge of the second top cover is connected to the hole wall of the connecting hole by laser welding.

12. The battery cell according to claim 6, wherein: The connection between the countersunk hole portion and the through hole portion is an arc structure.

13. The battery cell according to claim 6, wherein: A connection point between the first connection portion and the second connection portion is an arc structure, and a connection point between the countersunk hole portion and the through hole portion is an arc structure.

14. The battery cell according to claim 1, wherein: The connecting hole is a stepped hole, which includes a countersunk hole portion and a through hole portion that are interconnected. The outer edge of the second top cover has a step structure that matches the stepped hole. The step structure includes a first connecting portion and a second connecting portion that are interconnected. On the plane where the second top cover is located, the projection of the second connecting portion is located inside the projection of the first connecting portion; the through hole portion is connected to the second connecting portion.

15. The battery cell according to any one of claims 1 to 9, wherein: The connection hole is circular in shape.

16. A battery pack, wherein: The battery pack comprises: a battery cell as described in any one of claims 1-15.

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