Battery cell cover plate assembly, battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell cover plate assembly, a battery cell and a battery pack. The battery cell cover plate assembly comprises a cover plate, an anti-explosion valve, a plastic part and at least one supporting structure, the cover plate is provided with an assembly hole; the anti-explosion valve is arranged in the assembly hole; the plastic part is arranged on the first surface of the cover plate; the supporting structure is arranged between the cover plate and the plastic part, the melting point of the supporting structure is higher than that of the plastic part, the supporting structure is suitable for being supported between the pole group and the cover plate after the plastic part is melted due to high temperature in the battery cell, an exhaust channel communicated with the anti-explosion valve is formed, and the area among all parts of the supporting structure, the capacity of the battery cell and the voltage meet a preset relation. According to the invention, when thermal runaway of the battery cell occurs, the supporting structure supports the pole group to prevent the pole group from randomly moving along with high-temperature and high-pressure airflow to shield the anti-explosion valve on the cover plate, so that an exhaust channel communicated with the anti-explosion valve is kept between the pole group and the cover plate, the exhaust of the anti-explosion valve is not influenced, and the safety performance of the battery cell is improved.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a battery cover assembly, a battery cell and a battery pack. Background Art

[0002] Lithium-ion batteries have become the representative of modern high-performance batteries due to their high operating voltage, high specific energy, large capacity, low self-discharge, good cycle performance, long service life, light weight and small size.

[0003] Long-cell lithium-ion batteries are usually designed with tabs on both sides, and their structure includes: cell cover assembly, shell, pole group, electrolyte, etc. The cell cover assembly integrates structural parts such as pole column, explosion-proof valve and injection hole. After the cell cover assembly and the shell are welded, a closed space with a certain mechanical strength is formed to protect the pole group. The pole tabs on both sides of the pole group are fixed to the base of the pole column on both sides of the cover by laser welding to achieve electrical connection. The length direction of the cell is mainly fixed by the lower plastic insulating material on the inner side of the cover pressing on the pole group. The cover is integrated with an explosion-proof valve structure, which is mainly used for the directional discharge of internal high-temperature and high-pressure gas when the battery has thermal runaway due to internal short circuit, thereby improving the safety performance of the battery.

[0004] When this type of battery cell generates high temperature inside, the lower plastic will melt, causing its fixing effect on the electrode group to fail. The high-temperature and high-pressure gas inside the battery cell is exhausted in the direction of the explosion-proof valve. Under the push of the high-temperature and high-pressure gas, the electrode group will move toward the explosion-proof valve and block the explosion-proof valve, causing the exhaust channel to be blocked, thereby affecting the pressure relief effect of the battery cell and reducing the safety performance of the battery cell. Summary of the invention

[0005] In view of this, the present invention provides a battery cover assembly, a battery cell and a battery pack to solve the problem that when the high temperature generated inside the battery cell causes the lower plastic to melt, the electrode group blocks the explosion-proof valve and affects the exhaust pressure relief.

[0006] In a first aspect, the present invention provides a battery cell cover plate assembly, including a cover plate, an explosion-proof valve, a plastic part, and at least one supporting structure. The cover plate is provided with an assembly hole, and the cover plate has a first surface facing the pole group of the battery cell; the explosion-proof valve is provided in the assembly hole; the plastic part is provided on the first surface of the cover plate; the supporting structure is provided between the cover plate and the plastic part, the melting point of the supporting structure is higher than the melting point of the plastic part, and the supporting structure is suitable for supporting between the pole group and the cover plate after the plastic part melts due to the high temperature inside the battery cell, so as to form an exhaust channel connected to the explosion-proof valve; the supporting structure includes a bracket corresponding to the position of the explosion-proof valve, and the bracket is provided with a plurality of exhaust holes facing the explosion-proof valve, and the total area of ​​the exhaust holes is S2, in units of mm 2 , the total area of ​​the projection area of ​​the support structure along the Z direction in the XY plane is S, unit: mm 2 The effective support area of ​​the support structure in contact with the electrode group of the battery cell is S1, in mm2 , the capacity of the battery cell is A, unit Ah, the voltage is U, unit V, and it satisfies: 0.30≤S1 / CU≤0.45, 0.15≤S2 / S≤0.30.

[0007] Beneficial effect: The battery cell cover plate assembly provided by the present invention is provided with an explosion-proof valve protection structure. By providing a support structure with a melting point greater than that of the plastic part, when high-temperature and high-pressure gas is generated inside the battery cell, the plastic part melts and fails. At this time, the support structure has not melted, and the pole group has a tendency to move toward the explosion-proof valve under the action of the high-temperature and high-pressure gas. At this time, the support structure can effectively support and fix the pole group to avoid the pole group randomly moving with the high-temperature and high-pressure airflow to block the explosion-proof valve on the cover plate and affect the exhaust effect of the explosion-proof valve when the battery cell is thermally runaway. The support structure allows the pole group and the cover plate to maintain an exhaust channel connected to the explosion-proof valve, ensuring that the exhaust of the explosion-proof valve is not affected, thereby improving the safety performance of the battery cell. By limiting the relationship between the area, battery cell capacity and voltage of the various components of the support structure, it can be ensured that the support structure does not affect the exhaust effect of the explosion-proof valve while playing a stable supporting role for the pole group.

[0008] In an optional embodiment, the bracket includes a support plate arranged facing the explosion-proof valve and at least two support legs arranged at the edge of the support plate, and the exhaust hole is arranged on the support plate.

[0009] In an optional embodiment, the support structure further includes a boss disposed on the first surface of the cover plate, and the legs of the bracket are connected to the boss.

[0010] In an optional embodiment, the height of the exhaust channel is H1, 3mm≤H1≤6mm; and / or the height of the boss protruding from the first surface of the cover plate is H2, 1.0mm≤H2≤2.0mm.

[0011] In an optional implementation, two support structures are provided, and the two support structures are respectively arranged on both sides of the explosion-proof valve along the X direction.

[0012] In an optional implementation, the minimum distance between the boss close to the explosion-proof valve and the explosion-proof valve is L, 5mm≤L≤8mm.

[0013] In an optional embodiment, the support plate is provided with a plurality of exhaust holes; and / or, an exhaust gap communicating with the exhaust channel is provided between the support foot, the support plate and the cover plate.

[0014] In an optional embodiment, one of the boss and the leg is provided with an inserting protrusion, and the other is provided with an inserting hole that cooperates with the inserting protrusion. The boss and the leg are inserted through the cooperation of the inserting protrusion and the inserting hole, and are fixed by welding.

[0015] In a second aspect, the present invention further provides a battery cell, comprising a shell, a pole group and the battery cell cover assembly in the above technical solution, wherein the shell has an open end; the pole group is arranged in the shell; the battery cell cover assembly is arranged at the open end of the shell to encapsulate the pole group in the shell.

[0016] Beneficial effect: Because the battery cell includes the battery cell cover plate assembly, it has the same effect as the battery cell cover plate assembly and will not be described in detail here.

[0017] In a third aspect, the present invention further provides a battery pack, comprising the battery cell in the above technical solution.

[0018] Beneficial effect: Since the battery pack includes the battery cell, it has the same effect as the battery cell and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The figure is a schematic diagram of the exploded structure of an existing battery cell;

[0021] Figure 2 It is a partial structural schematic diagram of a battery cell cover plate assembly according to an embodiment of the present invention;

[0022] Figure 3 for Figure 2 Schematic diagram of the structure of the middle cover plate and the boss;

[0023] Figure 4 for Figure 2 Schematic diagram of the structure of the middle bracket;

[0024] Figure 5 This is a schematic structural diagram of a battery cell according to an embodiment of the present invention;

[0025] Figure 6 for Figure 5 Schematic diagram of the exploded structure of the battery cell shown;

[0026] Figure 7 for Figure 5 A top view of the battery cell shown;

[0027] Figure 8 for Figure 7 Sectional view along AA;

[0028] Fig. 9 for Figure 8A magnified view of the local structure.

[0029] Description of reference numerals:

[0030] 1. Cell cover assembly; 11. Cover; 12. Explosion-proof valve; 13. Plastic parts; 14. Support structure; 141. Boss; 142. Bracket; 1421. Support plate; 1422. Support foot; 1423. Exhaust hole; 1424. Exhaust gap; 143. Plug-in protrusion; 144. Plug-in hole; 15. Exhaust channel; 2. Shell; 3. Pole group. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0032] At present, traditional batteries, such as Figure 1 As shown, the battery cell includes a shell, both ends of the shell are open, and two battery cover plate assemblies are arranged at the two open ends. The battery cover plate assembly integrates a cover plate, a pole, an explosion-proof valve and a plastic part. A pole group is arranged in the shell, and the plastic part is between the cover plate and the pole group to support and fix the pole group.

[0033] In the length direction of the battery cell, the electrode group is mainly insulated and fixed by the lower plastic in the battery cell cover assembly, but this insulating material is generally made of PP material, and its strength and high temperature resistance are very limited, generally around 150 degrees Celsius, but the temperature at which the battery cell undergoes thermal runaway is usually much higher than the melting point of these insulating materials. When thermal runaway occurs inside the battery cell, these fixed structures inside the battery cell have melted and failed. At this time, only the electrode group is left inside the battery cell, and due to the melting of the insulating protective material, the gap between the electrode group and the cover and shell is increased. At this time, the electrode group has a high degree of freedom inside the battery cell. Since the high-temperature and high-pressure gas is exhausted in the direction of the explosion-proof valve, the electrode group will randomly move with the high-temperature and high-pressure airflow and block the explosion-proof valve on the cover, thereby blocking the exhaust channel, greatly reducing the exhaust effect of the explosion-proof valve and reducing the safety performance of the battery cell.

[0034] Combine the following Figures 2 to 9 , describing an embodiment of the present invention.

[0035] According to an embodiment of the present invention, in a first aspect, a battery cell cover plate assembly 1 is provided, comprising a cover plate 11, an explosion-proof valve 12, a plastic part 13 and at least one supporting structure 14. The cover plate 11 is provided with an assembly hole, and the cover plate 11 has a first surface facing the pole group 3 of the battery cell; the explosion-proof valve 12 is provided in the assembly hole; the plastic part 13 is provided on the first surface of the cover plate 11; the supporting structure 14 is provided between the cover plate 11 and the plastic part 13, the melting point of the supporting structure 14 is higher than the melting point of the plastic part 13, and the supporting structure 14 is suitable for supporting between the pole group 3 and the cover plate 11 after the plastic part 13 melts due to the high temperature inside the battery cell, so as to form an exhaust channel 15 connected with the explosion-proof valve 12; the supporting structure 14 comprises a bracket 142 corresponding to the position of the explosion-proof valve 12, and the bracket 142 is provided with a plurality of exhaust holes 1423 facing the explosion-proof valve 12, and the total area of ​​the exhaust holes 1423 is S2, in units of mm 2 The total area of ​​the projection area of ​​the support structure 14 along the Z direction in the XY plane is S, in mm 2 The effective support area of ​​the support structure 14 in contact with the electrode group 3 of the battery cell is S1, in mm 2 , the capacity of the battery cell is A, unit Ah, the voltage is U, unit V, and it satisfies: 0.30≤S1 / CU≤0.45, 0.15≤S2 / S≤0.30.

[0036] The battery cell cover plate assembly 1 provided by the present invention is provided with an explosion-proof valve 12 protection structure. By providing a support structure 14 with a melting point greater than that of the plastic part 13, when high-temperature and high-pressure gas is generated inside the battery cell, the plastic part 13 melts and fails. At this time, the support structure 14 has not melted, and the pole group 3 has a tendency to move toward the explosion-proof valve 12 under the action of the high-temperature and high-pressure gas. At this time, the support structure 14 can effectively support and fix the pole group 3 to avoid the pole group 3 randomly moving with the high-temperature and high-pressure airflow to block the explosion-proof valve 12 on the cover plate 11 and affect the exhaust effect of the explosion-proof valve 12 when thermal runaway occurs in the battery cell. The support structure 14 allows the pole group 3 and the cover plate 11 to maintain an exhaust channel 15 connected to the explosion-proof valve 12, thereby ensuring that the exhaust of the explosion-proof valve 12 is not affected, thereby improving the safety performance of the battery cell. By limiting the relationship between the area, cell capacity and voltage of each component of the support structure to meet the following conditions: 0.30≤S1 / CU≤0.45, 0.15≤S2 / S≤0.30, it can be ensured that the support structure can provide stable support for the electrode group without affecting the exhaust effect of the explosion-proof valve.

[0037] In some embodiments, the bracket 142 includes a support plate 1421 disposed facing the explosion-proof valve 12 and at least two legs 1422 disposed at the edge of the support plate 1421 , and the exhaust hole 1423 is disposed on the support plate 1421 .

[0038] In some embodiments, the support structure 14 further includes a boss 141 disposed on the first surface of the cover plate 11 , and the legs 1422 of the bracket 142 are connected to the boss 141 .

[0039] The support structure 14 adopts the structural form of the boss 141 and the bracket 142, which can facilitate the connection between the bracket 142 and the cover plate 11. Since the bracket 142 is connected to the boss 141, the bracket 142 and the boss 141 together constitute the protection structure of the explosion-proof valve 12. When the battery cell has thermal runaway and the plastic part 13 melts and fails, the battery cell moves to the position of the explosion-proof valve 12 under the impact of high-temperature and high-pressure gas. The bracket 142 and the boss 141 are both located between the cover plate 11 and the pole group 3, playing a supporting role. The sum of the height of the boss 141 protruding from the first surface of the cover plate 11 and the height of the bracket 142 is the height of the exhaust channel 15 between the pole group 3 and the cover plate 11.

[0040] The height of the side of the bracket 142 away from the cover plate 11 protruding from the first surface of the cover plate 11 is the height of the exhaust channel 15, and the height of the exhaust channel 15 is H1, 3mm≤H1≤6mm.

[0041] In some embodiments, the boss 141 protrudes from the first surface of the cover plate 11 by a height H2, where 1.0 mm ≤ H2 ≤ 2.0 mm.

[0042] The height H2 of the boss 141 protruding from the first surface of the cover plate 11 is in the range of 1.0 mm to 2.0 mm, so that the boss 141 can constitute a part of the support structure 14 in the Z direction. At the same time, it ensures that the boss 141 is easy to process and easy to connect with the bracket 142, providing a stable connecting support for the bracket 142.

[0043] In some embodiments, the boss 141 is configured as a prism, which facilitates processing.

[0044] In some embodiments, the bracket 142 includes a support plate 1421 and at least two legs 1422 arranged on the edge of the support plate 1421. The number and position of the bosses 141 correspond to the number and position of the legs 1422, and each leg 1422 is respectively connected to a boss 141.

[0045] By arranging the support legs 1422 on the edge of the support plate 1421 , the boss 141 and the bracket 142 are arranged correspondingly, so that one support leg 1422 is correspondingly connected to one boss 141 , and the bracket 142 and the cover plate 11 can be stably connected.

[0046] In this embodiment, two legs 1422 are respectively provided on two opposite sides of a support plate 1421, that is, one support plate 1421 is provided with four legs 1422. Four bosses 141 are provided in a group on the first surface of the cover plate 11, and the four bosses 141 are matched with the four legs 1422 in corresponding positions. The legs 1422 are welded to the bosses 141 to realize the fixed connection between the bracket 142 and the cover plate 11.

[0047] In some embodiments, the support plate 1421 is formed by stamping an aluminum plate. The support legs 1422 of the support plate 1421 are fixed to the surface of the boss 141 away from the cover plate 11 by welding, and the boss 141 and the support legs 142 are combined to form a protective structure of the explosion-proof valve 12.

[0048] In some embodiments, two support structures 14 are provided, and the two support structures 14 are respectively provided on both sides of the explosion-proof valve 12 along the X direction.

[0049] In this embodiment, two support structures 14 are provided. Specifically, on the first surface of the cover plate 11, two groups of bosses 141 are provided, and two brackets 142 are provided. The position and number of the bosses 141 in each group correspond to the position and number of the legs 1422 of the bracket 142. The two brackets 142 are respectively welded and fixed to the two groups of bosses 141.

[0050] By providing two support structures 14, the support effect of the support structure 14 on the electrode group 3 can be improved when the battery cell has thermal runaway. Because the two support structures 14 are respectively provided on both sides of the explosion-proof valve 12, the two support structures 14 can provide stable support for the electrode group 3 along the X direction, ensuring the stability of the support structure 14 supporting the electrode group 3 after the plastic part 13 fails due to melting, maintaining the balance of the electrode group 3, and further ensuring the smoothness of the exhaust channel 15.

[0051] Furthermore, in some embodiments, the two support structures 14 are symmetrically distributed on both sides of the explosion-proof valve 12 .

[0052] In some embodiments, the minimum distance between the boss 141 close to the explosion-proof valve 12 and the explosion-proof valve 12 is L, and 5 mm≤L≤8 mm.

[0053] The boss 141 close to the explosion-proof valve 12 is spaced apart from the explosion-proof valve 12, and the minimum distance of the spacing is controlled within the range of 5 mm to 8 mm, thereby ensuring that the support structure 14 can support the pole group 3 and keep the exhaust channel 15 unobstructed, thereby ensuring that the exhaust effect of the explosion-proof valve 12 is not affected.

[0054] In some embodiments, the support plate 1421 is provided with a plurality of exhaust holes 1423 ; and / or, an exhaust gap 1424 communicating with the exhaust channel 15 is provided between the support foot 1422 , the support plate 1421 and the cover plate 11 .

[0055] By providing a plurality of exhaust holes 1423 on the support plate 1421 , it is possible to facilitate gas flow through the exhaust holes 1423 , thereby improving the smoothness of flow of high-temperature and high-pressure gas in the exhaust channel 15 .

[0056] Furthermore, the support legs 1422 are used. Compared with the technical solution of the long strip flange formed outward by the support plate 1421, the support legs 1422 can make an exhaust gap 1424 exist between the support plate 1421 and the cover plate 11, further improving the flowability of the gas in the exhaust channel 15. At the same time, the material used for the support 142 can be reduced, and the overall weight of the battery cover plate assembly 1 can be reduced.

[0057] When thermal runaway occurs inside the battery cell, the bracket 142 first supports the electrode group 3, so that the exhaust channel 15 is maintained between the electrode group 3 and the explosion-proof valve 12. In addition, the exhaust holes 1423 on the support plate 1421 and the exhaust gap 1424 in the Z direction between the support leg 1422, the bracket 142 and the cover plate 11 are connected to the exhaust channel 15, which can ensure the exhaust requirements.

[0058] In some embodiments, one of the boss 141 and the leg 1422 is provided with an inserting protrusion 143, and the other is provided with an inserting hole 144 that cooperates with the inserting protrusion 143. The boss 141 and the leg 1422 are inserted through the matching of the inserting protrusion 143 and the inserting hole 144, and are fixed by welding.

[0059] In this embodiment, the boss 141 is provided with a plug-in protrusion 143, and the leg 1422 is provided with a plug-in hole 144. When the bracket 142 and the boss 141 are fixedly connected, the plug-in hole 144 of the leg 1422 is plugged and matched with the plug-in protrusion 143 of the boss 141, and then the boss 141 and the leg 1422 are welded and fixed. This arrangement can further improve the welding effect and ensure the overall structural strength of the support structure 14.

[0060] The plug hole 144 can be a through hole or a blind hole, depending on the actual situation.

[0061] The following provides specific cases for testing, with a total of 12 groups tested, each group having 6 test cells, to verify the technical effect brought by the technical solution of the present invention. The specific results are shown in Table 1.

[0062] Specifically, the object of the test is a battery cell assembled by the battery cell cover plate assembly. Except for the variables in Table 1, the other factors and test conditions are the same.

[0063] Table 1:

[0064]

[0065] According to Table 1, the size design of the support structure 14 has a great influence on the safety performance of the single cell. First, S1 / CU ≥ 0.30 is required to ensure the support area. If the support surface is too large, it will affect the exhaust channel, so S1 / CU ≤ 0.45 is required; in addition, 0.15 ≤ S2 / S ≤ 0.30 is required to ensure that the S2 area is appropriate. If S2 is too small, the exhaust effect is not good. If S2 is too large, the strength of the support structure 14 will be affected.

[0066] According to an embodiment of the present invention, in a second aspect, a battery cell is further provided, comprising a shell 2, a pole group 3 and the battery cell cover assembly 1 in the above embodiment, wherein the shell 2 has an open end; the pole group 3 is disposed in the shell 2; the battery cell cover assembly 1 is disposed at the open end of the shell 2 to encapsulate the pole group 3 in the shell 2.

[0067] Because the battery cell includes the battery cell cover plate assembly 1, it has the same effect as the battery cell cover plate assembly 1, and will not be described in detail here.

[0068] According to an embodiment of the present invention, in a third aspect, a battery pack is further provided, comprising the battery cell in the above embodiment.

[0069] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be described in detail here.

[0070] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery cover assembly, characterized in that: include: A cover plate, wherein the cover plate is provided with an assembly hole, and the cover plate has a first surface facing the electrode group of the battery cell; An explosion-proof valve, the explosion-proof valve being arranged in the assembly hole; A plastic part, the plastic part is arranged on the first surface of the cover plate; At least one supporting structure, the supporting structure is arranged between the cover plate and the plastic part, the melting point of the supporting structure is higher than the melting point of the plastic part, and an exhaust channel connected to the explosion-proof valve is formed between the electrode group and the cover plate; The support structure includes a bracket corresponding to the position of the explosion-proof valve, and the bracket is provided with a plurality of exhaust holes facing the explosion-proof valve, and the total area of ​​the exhaust holes is S2, in units of mm 2 The total area of ​​the projection area of ​​the support structure along the Z direction in the XY plane is S, in mm 2 The effective support area of ​​the support structure in contact with the electrode group of the battery cell is S1, in mm 2 , the capacity of the battery cell is A, unit is Ah, the voltage is U, unit is V, satisfying: 0.30≤S1 / CU≤0.45, 0.15≤S2 / S≤0.

30.

2. The battery cover assembly according to claim 1, characterized in that: The bracket comprises a support plate arranged facing the explosion-proof valve and at least two support legs arranged at the edge of the support plate, and the exhaust hole is arranged on the support plate.

3. The battery cover assembly according to claim 2, characterized in that: The support structure further includes a boss disposed on the first surface of the cover plate, and the legs of the bracket are connected to the boss.

4. The battery cover assembly according to claim 3, characterized in that: The height of the exhaust passage is H1, 3mm≤H1≤6mm; And / or, the height of the boss protruding from the first surface of the cover plate is H2, 1.0mm≤H2≤2.0mm.

5. The battery cell cover plate assembly according to any one of claims 1 to 4, characterized in that: There are two support structures, and the two support structures are respectively arranged on both sides of the explosion-proof valve along the X direction.

6. The battery cover assembly according to claim 3 or 4, characterized in that: The minimum distance between the boss close to the explosion-proof valve and the explosion-proof valve is L, 5mm≤L≤8mm.

7. The battery cover assembly according to claim 4, characterized in that: The support plate is provided with a plurality of exhaust holes; And / or, an exhaust gap communicating with the exhaust channel is provided between the support foot, the support plate and the cover plate.

8. The battery cover assembly according to claim 4, characterized in that: One of the boss and the leg is provided with an inserting protrusion, and the other is provided with an inserting hole matched with the inserting protrusion. The boss and the leg are inserted through the matching of the inserting protrusion and the inserting hole, and are fixed by welding.

9. A battery cell, characterized in that: include: a housing having an open end; A pole group, the pole group is arranged in the shell; The battery cell cover plate assembly according to any one of claims 1 to 8, wherein the battery cell cover plate assembly is arranged at the open end of the shell, and the electrode group is encapsulated in the shell.

10. A battery pack, characterized in that: Comprising the battery cell as claimed in claim 9.

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