Cover plate assembly and battery cell

Abstract

A cover plate assembly (10) and a battery cell (100). The battery cell (100) comprises a casing (20), a cell package (30), and a cover plate assembly (10). The casing (20) forms an accommodating cavity having an opening. The cell package (30) is arranged in the accommodating cavity. The cover plate assembly (10) can seal the opening of the accommodating cavity. The cover plate assembly (10) comprises a supporting body (101), a notch (221) is formed on the supporting body (101), the area formed by the inner ring of the notch (221) is S, and S satisfies: S=(K×C) / (T×V), wherein K is the gas production coefficient of the cell package, C is the capacity of the cell package, T is the pressure relief time, and V is the pressure relief velocity.

Description

Cover plate assembly and battery cell

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on June 21, 2023, with application number CN202321588793.4. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a cover plate assembly and a battery cell. Background Art

[0003] To mitigate explosions caused by thermal runaway and other factors during battery cell operation, the cover assembly is typically equipped with an explosion-proof pressure relief structure. In related technologies, a common pressure relief structure involves notching the pressure relief component. These notches create a weak zone, causing the cell to explode preferentially at the notch when excessive pressure builds up inside the cell. This provides directional pressure relief and improves the cell's safety. SUMMARY OF THE INVENTION

[0004] However, in related technologies, the setting of notches is usually estimated by empirical values, which may lead to the following problems: (1) The gas production during the life cycle of the battery cell is large, causing the pressure relief structure to explode prematurely and the battery cell to fail; (2) When the battery cell encounters an abnormality such as a short circuit, the gas production increases rapidly, resulting in a high gas overflow rate when the pressure relief structure explodes, causing a safety hazard.

[0005] The present application provides a cover plate assembly. The cover plate assembly is configured to enclose a shell containing a core package, and the cover plate assembly includes: a support body, a notch is provided on the support body, and the area formed by the inner circle of the notch is S, where S satisfies:

[0006]

[0007] Among them, K is the gas production coefficient of the core package, C is the capacity of the core package; T is the pressure relief time; V is the pressure relief speed.

[0008] The present application also provides a battery cell, which includes a housing, a core pack, and the aforementioned cover assembly, wherein the housing has an opening on one side, the core pack is disposed within the housing, and the cover assembly closes the opening. Beneficial effects

[0009] The cover assembly provided in the present application has an area enclosed by the notch, which is the effective pressure relief area of ​​the cover assembly, and the effective pressure relief area is jointly limited by the gas production coefficient of the core package, the capacity of the core package, the pressure relief time and the pressure relief speed. Through the above-mentioned limitation, on the one hand, it is ensured that under the premise of normal gas production of the battery cell, the notch is not easy to burst prematurely to prevent the battery cell from failing prematurely; on the other hand, it can prevent the gas overflow speed of the battery cell from being too high during pressure relief, thereby ensuring the safety of the pressure relief process.

[0010] The battery cell provided in the present application can improve the problem of premature failure of the battery cell by providing the above-mentioned cover plate assembly, and the pressure relief process is safe. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG1 is an exploded view of a battery cell provided in some embodiments of the present application;

[0012] FIG2 is a schematic structural diagram of a pressure relief member provided in some embodiments of the present application;

[0013] FIG3 is a schematic diagram of the cover plate body and the pressure relief member in cooperation with each other in some embodiments of the present application;

[0014] FIG4 is a schematic structural diagram of a cover body and pins provided in some embodiments of the present application.

[0015] In the picture:

[0016] 10. Cover assembly; 101. Support body; 1. Cover body; 11. Mounting hole; 111. First hole; 112. Second hole; 2. Pressure relief member; 21. Connecting portion; 22. Main body; 221. Notch; 2211. Semicircular arc segment; 2212. Straight segment; 3. Protective film; 31. Ventilation hole; 4. Terminal; 5. Pin;

[0017] 20. Shell;

[0018] 30. Core package;

[0019] 100. Battery cell. Modes for Carrying Out the Invention

[0020] In the description of the embodiments of this application, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on the specific circumstances.

[0021] In the embodiments of the present application, unless otherwise expressly specified and limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0022] In the description of the embodiments of this application, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meaning.

[0023] This embodiment provides a cover plate assembly 10 and a battery cell 100. The following description will be made using a square battery cell as an example. As shown in FIG1 , the battery cell 100 includes a shell 20, a core pack 30, and a cover plate assembly 10. The shell 20 forms a receiving cavity with an opening on one side, and the core pack 30 is arranged in the receiving cavity of the shell 20. The cover plate assembly 10 can close the opening of the shell 20, thereby closing the receiving cavity. In this embodiment, the shell 20 is constructed as a rectangular parallelepiped structure, and an opening is formed on one side of the shell 20. The number of core packs 30 can be one, two, or more, and is not limited here. The core pack 30 has a positive tab and a negative tab. The cover plate assembly 10 includes a support body 101, two poles 4, and two pins 5. Among the two pins 5, one is connected to the positive tab of the core pack 30, and the other is connected to the negative tab of the core pack 30. The support body 101 is constructed in a rectangular shape and closes the opening of the shell 20. The two poles 4 are both connected to the cover body 1 . The two poles 4 pass through the support body 101 from outside to inside and are respectively connected to the two pins 5 , so that the current of the core package 30 can be conducted through the pins 5 and the poles 4 in sequence.

[0024] In order to alleviate the explosion of the battery cell 100 due to thermal runaway of the core package 30 during use, as shown in Figures 1 and 2, a notch 221 is provided on the support body 101. The provision of the notch 221 forms a weak area of ​​strength on the support body 101. When the air pressure in the accommodating cavity of the battery cell 100 is too high, the battery cell 100 will preferentially explode from the notch 221, thereby achieving directional pressure relief to prevent the battery cell 100 from exploding. In this embodiment, the support body 101 includes a cover body 1 and a pressure relief member 2. The cover body 1 is provided with a mounting hole 11. The pressure relief member 2 is separately connected to the mounting hole 11 to ensure the sealing of the battery cell 100. The notch 221 is provided on the pressure relief member 2. The support body 101 is provided to include two components, the cover body 1 and the pressure relief member 2, so that the strength of the materials selected for the two can be adjusted as needed. In other embodiments, the support body 101 can also be provided as an independent plate, and the notch 221 is directly provided on the plate.

[0025] In the related art, the size of the notch 221 is usually estimated using empirical values, which may cause the following problems: (1) The battery cell 100 produces a large amount of gas during its life cycle, causing the pressure relief structure to explode prematurely and the battery cell 100 to fail; (2) The battery cell 100 encounters an abnormality such as a short circuit, and the gas production increases rapidly, causing the gas to overflow at a high speed when the pressure relief structure explodes, posing a safety hazard.

[0026] In this regard, in this embodiment, the area formed by the inner circle of the notch 221 is defined as S. In fact, S constitutes the effective pressure relief area when the battery cell 100 is depressurized. S satisfies:

[0027] Formula (1)

[0028] In formula (1), K is the gas production coefficient of the core package 30, C is the capacity of the core package 30, T is the pressure relief time, and V is the pressure relief speed.

[0029] In this embodiment, the design logic of formula (1) is: total pressure relief gas volume = pressure relief speed × pressure relief time × effective pressure relief area, where K × C constitutes the total pressure relief gas volume. When designing the enclosed area of ​​the notch 221 on the pressure relief member 2, the pressure relief time T and the pressure relief speed V can be set. The gas production coefficient K of the core package 30 and the capacity C of the core package 30 are the performance parameters of the core package 30 itself. Therefore, referring to the above formula (1), the quantitative value of the effective pressure relief area S can be obtained. Under this quantitative value, it can be ensured that when the battery cell 100 produces gas normally, the pressure relief member 2 is not likely to explode prematurely, thereby preventing the battery cell 100 from failing prematurely. Under this quantitative value, it can also prevent the battery cell 100 from overflowing too quickly during pressure relief, thereby ensuring the safety of the pressure relief process.

[0030] In this embodiment, the pressure relief speed V=1m / s~17m / s, and the pressure relief speed range is a safe pressure relief speed. When the battery cell 100 is depressurized, the risk to the user's personal safety is low. Specifically, the value of V can be 1m / s, 5m / s, 10m / s, 15m / s, 17m / s, etc. Optionally, the pressure relief time T=10s~30s. Specifically, the value of T can be 10s, 15s, 20s, 25s, 30s, etc. Optionally, in this embodiment, the gas production coefficient K of the core package 30 is 0.20~2.5. It can be understood that the range of the gas production coefficient K is only a range.

[0031] In this embodiment, as shown in FIG3 , the notch 221 includes two semicircular arc segments 2211 and two straight line segments 2212. The semicircular arc segments 2211 and the straight line segments 2212 are alternately arranged and sequentially connected to enclose a closed figure. This kind of figure has smooth lines, so the notch 221 is not prone to local stress concentration. When the air pressure in the battery cell 100 is too high, each position of the notch 221 can be evenly exploded. In this embodiment, the first direction and the second direction are defined as two directions perpendicular to each other in the plane where the cover body 1 is located, wherein the X direction in FIG3 represents the first direction and the Y direction represents the second direction. The maximum size of the figure enclosed by the notch 221 in the first direction is L1, and the maximum size in the second direction is L2. Then the area enclosed by the inner circle of the notch 221 is:

[0032] Formula (2)

[0033] Therefore, the values ​​of L1 and L2 can be set by combining formula (1) and formula (2). In other embodiments, the shape of the pattern enclosed by the notch 221 can also be a circle, a rectangle or other irregular shapes, which are not specifically limited here.

[0034] In some embodiments, as shown in FIG3 , the dimension of the cover plate body 1 in the first direction is B. For example, B ≥ L1 + 5 mm. The 5 mm in this formula is the space reserved for the connection between the pressure relief member 2 and the cover plate body 1 in the first direction, thereby ensuring a secure connection between the pressure relief member 2 and the cover plate body 1. Similarly, W ≥ L2 + 5 mm. The 5 mm in this formula is the space reserved for the connection between the pressure relief member 2 and the cover plate body 1 in the second direction, thereby ensuring a secure connection between the pressure relief member 2 and the cover plate body 1.

[0035] In this embodiment, as shown in Figure 2, the pressure relief member 2 includes a main body 22 and a connecting portion 21, a notch 221 is provided on the main body 22, and the connecting portion 21 is provided around the main body 22. The thickness of the connecting portion 21 is greater than that of the main body 22, and the connecting portion 21 is welded to the cover body 1. By setting the thickness of the connecting portion 21 to be greater than that of the main body 22, it is ensured that the connecting portion 21 has sufficient thickness, and thus the welding connection between the pressure relief member 2 and the cover body 1 is more secure. In this embodiment, both the cover body 1 and the pressure relief member 2 are made of aluminum material, so as to facilitate the welding connection between the two. For example, the pressure relief member 2 is annealed to appropriately reduce the strength of the pressure relief member 2, so that when the air pressure in the battery cell 100 is too high, it can explode from the notch 221 in time.

[0036] In some embodiments, the ratio of the depth of the notch 221 to the thickness of the main body 22 is 0.4 to 0.8. Setting the depth of the notch 221 within this range ensures that the pressure relief member 2 has a certain strength, thereby preventing damage during normal operation of the core package 30 and allowing the core package 30 to explode promptly from the notch 221 in special circumstances such as a short circuit.

[0037] In some embodiments, the notch 221 is disposed on the side of the pressure relief member 2 facing away from the core package 30, that is, the notch 221 is disposed on the side of the pressure relief member 2 facing the outside of the battery cell 100. The surface at the notch 221 is not smooth, and the electrolyte in the battery cell 100 is prone to corroding the uneven surface. In this embodiment, by disposing the notch 221 on the outside of the battery cell 100, corrosion of the notch 221 by the electrolyte can be avoided, thereby ensuring the structural reliability of the battery cell 100.

[0038] In some embodiments, as shown in FIG4 , the mounting hole 11 is a stepped hole comprising a first hole 111 and a second hole 112. The first hole 111 is located on the side of the cover plate body 1 facing the core package 30. The cross-sectional area of ​​the first hole 111 is larger than that of the second hole 112. The pressure relief member 2 is disposed within the first hole 111. Therefore, the stepped surface formed by the first and second holes 111 and 112 serves to limit the position of the pressure relief member 2, thereby ensuring the positional accuracy of the pressure relief member 2 during installation. In this embodiment, the pressure relief member 2 is welded to the cover plate body 1 after being placed within the first hole 111.

[0039] In some embodiments, as shown in FIG1 , the cover plate assembly 10 further includes a protective film 3 for sealing the second hole 112 , thereby preventing external impurities from being deposited in the notch 221 of the pressure relief member 2 , thereby ensuring the reliability of the pressure relief member 2 .

[0040] A cavity is formed between the pressure relief member 2, the inner wall of the mounting hole 11, and the protective film 3. The air pressure within this cavity changes with the use of the battery cell 100, which can cause the protective film 3 to be pulled. In some embodiments, the protective film 3 is provided with vents 31. The provision of vents 31 ensures that the air pressure within the cavity is balanced with the external atmosphere, thereby preventing the protective film 3 from being pulled and damaged.

Claims

1. A cover plate assembly (10), capable of enclosing a housing (20) containing a core package (30), comprising: A support body (101), wherein a notch (221) is provided on the support body (101), and an area formed by an inner circle of the notch (221) is S, wherein S satisfies: Wherein, K is the gas production coefficient of the core package (30), C is the capacity of the core package (30); T is the pressure relief time; and V is the pressure relief speed.

2. The cover plate assembly (10) according to claim 1, wherein: The gas generation coefficient K of the core package (30) is 0.20-2.5; and / or the pressure relief time T is 10s-30s; and / or the pressure relief speed V is 1m / s-17m / s.

3. The cover plate assembly (10) according to claim 1, wherein: The notch (221) comprises two semicircular arc segments (2211) and two straight line segments (2212), and the semicircular arc segments (2211) and the straight line segments (2212) are alternately arranged and sequentially connected to enclose and form a closed figure.

4. The cover plate assembly (10) according to claim 1, wherein: The notch (221) is arranged on a side of the support body (101) facing away from the core package (30).

5. The cover plate assembly (10) according to any one of claims 1 to 4, wherein: The supporting body (101) comprises: a cover plate body (1), and a mounting hole (11) is provided on the cover plate body (1); A pressure relief piece (2), the pressure relief piece (2) being enclosed in the mounting hole (11), and the notch (221) being arranged on the pressure relief piece (2).

6. The cover plate assembly (10) according to claim 5, wherein: The notch (221) is arranged on the main body (22) of the pressure relief member (2), and the ratio of the depth of the notch (221) to the thickness of the main body (22) is 0.4-0.

8.

7. The cover plate assembly (10) according to claim 5, wherein: The maximum dimension of the figure enclosed by the notch (221) in the first direction is L1, and the maximum dimension in the second direction is L2. The dimension of the cover plate body (1) in the first direction is B, and the dimension in the second direction is W, wherein B≥L1+5mm; W≥L2+5mm.

8. The cover plate assembly (10) according to claim 5, wherein: The area S enclosed by the inner circle of the notch (221) is: Wherein, L1 is the maximum dimension of the figure enclosed by the notch (221) in the first direction, L2 is the maximum dimension of the figure enclosed by the notch (221) in the second direction, and the first direction and the second direction are two directions perpendicular to each other in the plane where the cover plate body (1) is located.

9. The cover plate assembly (10) according to claim 5, wherein: The mounting hole (11) is a stepped hole, comprising a first hole (111) and a second hole (112), the first hole (111) being arranged on a side of the cover plate body (1) facing the core package (30), the cross-sectional area of ​​the first hole (111) being larger than that of the second hole (112), and the pressure relief member (2) being arranged in the first hole (111).

10. The cover plate assembly (10) according to claim 9, further comprising a protective film (3), wherein the protective film (3) is configured to close the second hole (112).

11. The cover plate assembly (10) according to claim 10, wherein: A cavity is formed between the pressure relief component (2), the inner wall of the mounting hole (11) and the protective film (3).

12. The cover plate assembly (10) according to claim 11, wherein: The protective film (3) is provided with ventilation holes (31).

13. The cover plate assembly (10) according to claim 5, wherein: The pressure relief member (2) comprises: A main body (22), wherein the notch (221) is arranged on the main body (22); The connecting portion (21) is arranged around the main body portion (22), the thickness of the connecting portion (21) is greater than that of the main body portion (22), and the connecting portion (21) is connected to the cover plate main body (1) by welding.

14. The cover plate assembly (10) according to claim 5, wherein: The pressure relief component (2) and the cover plate body (1) are both made of aluminum.

15. The cover plate assembly (10) according to claim 14, wherein: The pressure relief component (2) is an annealed component that has been annealed.

16. The cover plate assembly (10) according to any one of claims 1 to 4, wherein: The supporting body (101) is an independent plate, and the notch (221) is provided on the plate.

17. A battery cell (100), comprising a shell (20), a core package (30) and a cover plate assembly (10) according to any one of claims 1 to 16, wherein one side of the shell (20) is open, the core package (30) is arranged in the shell (20), and the cover plate assembly (10) closes the opening.

18. The battery cell (100) according to claim 17, wherein: The cover plate assembly (10) further comprises a pole (4), wherein the pole (4) is penetrated through the support body (101).

19. The battery cell (100) according to claim 18, wherein: The cover plate assembly (10) further comprises a pin (5), wherein the pin (5) connects the pole (4) and the core package (30).

20. The battery cell (100) according to claim 17, wherein: The battery cell (100) is a square battery cell.

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