Top cover assembly, battery cell and battery pack

Abstract

Provided in the present application are a top cover assembly, a battery cell and a battery pack. The top cover assembly comprises a plastic member and a cover plate, wherein a pressure relief port is constructed in the cover plate; the plastic member is connected to the side of the cover plate close to an electrode assembly; the plastic member has a rupture region; and the rupture region is arranged close to the pressure relief port, and is configured to rupture when subjected to the action of the internal gas pressure of a battery cell.

Description

Top cover assembly, individual battery cells and battery pack

[0001] This application claims priority to Chinese patent applications filed on December 31, 2024, with application numbers 202423319860.X and 202411997437.7, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, specifically to a top cover assembly, a single battery cell, and a battery pack. Background Technology

[0003] In the field of battery technology, battery explosion-proof valves are typically formed onto the top cover assembly using either stamping or welding. For explosion-proof valves formed by stamping, stamping can damage the surface plating, resulting in exposed metal and reduced corrosion resistance. For explosion-proof valves formed by welding, welding can introduce defects into the top cover assembly, thereby reducing its safety. Invention Overview

[0004] However, for explosion-proof valves stamped into the top cover assembly, nickel plating is typically used to improve corrosion resistance, followed by surface pickling. Nickel plating strengthens the grooves on the explosion-proof valve, while pickling causes some corrosion to the grooves. For explosion-proof valves welded into the top cover assembly, welding is not suitable for all metals, resulting in limited applicability.

[0005] This application provides a top cover assembly applied to a battery cell. The battery cell includes an electrode assembly, and the top cover assembly includes a cover plate and a plastic part. The cover plate is configured with a pressure relief port, and the plastic part is connected to the side of the cover plate near the electrode assembly. The plastic part has a fracture zone located near the pressure relief port and is configured to fracture under the action of internal air pressure of the battery cell.

[0006] This application also provides a single battery cell, including the top cover assembly as described above.

[0007] This application also provides a battery pack, including the single battery cell as described above. Beneficial effects

[0008] The top cover assembly provided in this application forms an explosion-proof valve structure by creating a fracture zone on the plastic part and a pressure relief port on the cover plate, and the two are combined to form an explosion-proof valve structure. This allows the explosion-proof valve structure to be formed on the top cover assembly without stamping or welding. At the same time, the plastic part can be injection molded, which allows for good control of the thickness of the fracture zone, so as to control the opening force of the explosion-proof valve and ensure the stability of the opening force of the explosion-proof valve. Attached Figure Description

[0009] Figure 1 is a perspective view of the top cover assembly provided in an embodiment of this application;

[0010] Figure 2 is a cross-sectional view of the top cover assembly provided in an embodiment of this application;

[0011] Figure 3 is an enlarged view of part A in Figure 2;

[0012] Figure 4 is one of the schematic diagrams of the depressurization state of the top cover assembly provided in the embodiments of this application;

[0013] Figure 5 is a second schematic diagram of the depressurization state of the top cover assembly provided in an embodiment of this application.

[0014] Explanation of reference numerals in the attached figures:

[0015] 10. Cover plate; 110. Pressure relief port; 120. First plate; 130. Second plate; 20. Plastic part; 210. Fracture zone; 220. Central axis; 230. Groove; 240. First protrusion; 250. Second protrusion; 2510. First raised section; 2520. Second raised section; 2530. Air chamber; 260. Main body; 2610. Mounting channel; 270. First connecting part; 280. Second connecting part; 2810. First slot; 290. Bending part; 2910. Second slot; 30. Terminal assembly; 310. Snap-fit ​​part; 40. Housing; 50. Current collector. Embodiments of the present invention

[0016] As shown in Figures 1 to 5, this application provides a top cover assembly. This top cover assembly is applied to a battery cell. The battery cell includes an electrode assembly. The top cover assembly includes a plastic part 20 and a cover plate 10. A pressure relief port 110 is formed on the cover plate 10. The plastic part 20 is connected to the side of the cover plate 10 near the electrode assembly. The plastic part 20 has a fracture region 210. The fracture region 210 is located near the pressure relief port 110. The fracture region 210 is configured to fracture under the action of internal air pressure within the battery cell.

[0017] In this embodiment, by forming a fracture zone 210 on the plastic part 20 and a pressure relief port 110 on the cover plate 10, the two are combined to form an explosion-proof valve structure. This allows the explosion-proof valve structure to be formed on the top cover assembly without stamping or welding. Furthermore, the plastic part 20 can be injection molded, which allows for precise control of the thickness of the fracture zone 210, facilitating control of the opening force of the explosion-proof valve and ensuring its stability.

[0018] It is understandable that when the electrode assembly of the battery cell is punctured or otherwise damaged, the electrode assembly will generate a large amount of gas. If this gas continues to accumulate inside the battery cell casing 40, it will pose a serious safety hazard. In this embodiment, a fracture zone 210 is formed on the plastic part 20. When the gas pressure inside the casing 40 reaches a certain level, the gas pressure inside the casing 40 can cause the fracture zone 210 to break. After the fracture zone 210 breaks, the gas can be discharged from the fracture point of the plastic part 20 and the pressure relief port 110 of the cover plate 10.

[0019] A plastic component 20 is disposed between the cover plate 10 and the electrode assembly. The plastic component 20 is made of insulating plastic material, thus achieving insulation between the cover plate 10 and the electrode assembly. Simultaneously, the plastic component 20 prevents the cover plate 10 from contacting the electrolyte, preventing corrosion. Based on its inherent corrosion resistance, the fracture zone 210 is formed within the plastic component 20, further preventing electrolyte corrosion of the explosion-proof valve structure and ensuring its stability.

[0020] Since the plastic part 20 can be injection molded, the thickness of each location of the plastic part 20 is easily controlled. Therefore, the injection thickness of the fracture zone 210 of the plastic part 20 can be controlled to control the opening value of the explosion-proof valve structure. The tensile strength of the plastic part 20 can also be controlled by controlling the injection thickness of other areas of the plastic part 20.

[0021] As shown in Figure 2, in some embodiments, the projection of the fracture zone 210 along the height direction of the cell at least partially covers the pressure relief port 110.

[0022] It is understandable that the projection of the fracture zone 210 should at least cover the pressure relief port 110. When the plastic part 20 breaks at the location of the fracture zone 210, the gas can escape from the pressure relief port 110 to prevent the gas from accumulating in the cell casing 40 and causing safety hazards.

[0023] In some embodiments, the projection of the fracture zone 210 along the height direction of the cell exactly covers the pressure relief port 110.

[0024] In some embodiments, the projection of the fracture region 210 extends beyond the periphery of the pressure relief port 110 along the height direction of the battery cell. For example, the pressure relief port 110 is configured as annular, and the fracture region 210 is also configured as annular. The inner diameter of the fracture region 210 is smaller than the inner diameter of the pressure relief port 110. The outer diameter of the fracture region 210 is larger than the outer diameter of the pressure relief port 110.

[0025] In some embodiments, the plastic part 20 is injection molded onto the cover plate 10.

[0026] It is understandable that the cover plate 10 is a metal part. The plastic part 20 is injection molded onto the cover plate 10 to ensure a reliable connection between the two and to facilitate the manufacturing of the top cover assembly. For example, the cover plate 10 can be placed in the injection mold before the plastic part 20 is injection molded, and after the plastic part 20 is injection molded, the plastic part 20 and the cover plate 10 are directly connected.

[0027] As shown in Figure 3, in some embodiments, at least a portion of the fracture region 210 has a decreasing thickness along the direction from the edge of the fracture region 210 to the central axis 220 of the fracture region 210.

[0028] It is understood that the thickness of at least a portion of the fracture zone 210 decreases, and when it decreases to the position of minimum thickness, that position can fracture under air pressure. In this embodiment, the thickness of the fracture zone 210 is reduced to be less than the thickness of other areas of the plastic part 20, ensuring that it can fracture at the position of the fracture zone 210 under air pressure.

[0029] As shown in Figure 3, along the direction from the edge of the fracture region 210 to the central axis 220 of the fracture region 210, the thickness of the fracture region 210 first decreases and then remains constant. The region where the thickness remains constant is the minimum thickness region of the fracture region 210. Under the action of the gas pressure inside the battery cell, the minimum thickness location of the fracture region 210 will fracture.

[0030] In some embodiments, the thickness of at least a portion of the fracture region 210 may decrease linearly or exponentially.

[0031] In some embodiments, the fracture region 210 may be formed with a slope, arc surface, or other structure on the side near the cover plate 10 to reduce the thickness of the fracture region 210. Alternatively, the fracture region 210 may be formed with a slope, arc surface, or other structure on the side near the electrode assembly to reduce the thickness of the fracture region 210. Alternatively, both sides of the fracture region 210 may be formed with a slope, arc surface, or other structure to reduce the thickness of the fracture region 210.

[0032] Please continue to refer to Figure 3. In some embodiments, the minimum thickness of the fracture zone 210 is D, which satisfies: 0.1 mm ≤ D ≤ 0.8 mm.

[0033] Understandably, under the influence of internal air pressure, the fracture zone 210 will fracture at its minimum thickness. The minimum thickness of the fracture zone 210 can be selected based on the opening value of the explosion-proof valve of the top cover assembly. Specifically, the minimum thickness of the fracture zone 210 is positively correlated with the opening value of the explosion-proof valve of the top cover assembly. A larger opening value results in a larger minimum thickness of the fracture zone 210; conversely, a smaller opening value results in a smaller minimum thickness of the fracture zone 210.

[0034] It should be noted that when the minimum thickness of the fracture zone 210 is greater than 0.8 mm, the height of the fracture zone 210 will be too large, causing the opening value of the explosion-proof valve of the top cover assembly to be too high, failing to meet the usage requirements. Simultaneously, a minimum thickness of the fracture zone 210 greater than 0.8 mm will also cause the first protrusion 240 on the plastic part 20 to protrude beyond the pressure relief port 110, affecting the appearance of the top cover assembly. When the minimum thickness of the fracture zone 210 is less than 0.1 mm, the fracture zone 210 cannot be injection molded. Therefore, in this embodiment, the thickness of the minimum thickness region of the fracture zone 210 is set within the range of 0.1 mm to 0.8 mm to ensure that the plastic part 20 can be molded by injection molding, to ensure that the explosion-proof valve of the top cover assembly has a suitable opening value, and to prevent the first protrusion 240 from passing through the pressure relief port 110.

[0035] For example, the minimum thickness of the fracture zone 210 is set to 0.1 mm, 0.2 mm, 0.5 mm, 0.8 mm, or any value between the two.

[0036] Please continue referring to Figure 3. In some embodiments, a groove 230 is formed on the side of the plastic part 20 away from the cover plate 10. The fracture zone 210 is located on the plastic part 20 corresponding to the groove 230.

[0037] It is understandable that if a groove 230 is formed on the side of the plastic part 20 away from the cover plate 10, the thickness of the plastic part 20 at the location of the groove 230 will be less than the thickness of other areas of the plastic part 20. As a result, under air pressure, the location of the groove 230 is more likely to break, thus forming a fracture zone 210 on the plastic part 20 corresponding to the location of the groove 230.

[0038] In some embodiments, the cross-section of the groove 230 can be set to any shape such as trapezoidal, semi-circular, semi-elliptical, arc, polygon, etc., to ensure that the curvature of the plastic part 20 at the position of the groove 230 is less than the thickness of other areas of the plastic part 20.

[0039] As shown in Figures 2 and 3, in some embodiments, the plastic part 20 is configured with a first protrusion 240 protruding toward the cover plate 10. The first protrusion 240 is engaged with the pressure relief port 110.

[0040] Understandably, by using the first protrusion 240 to snap onto the plastic part 20, the pressure relief port 110 can be filled, thereby increasing the strength of the cover plate 10. Since the first protrusion 240 can snap onto the pressure relief port 110, the position of the first protrusion 240 will match the position of the fracture zone 210, and the first protrusion 240 is unlikely to affect the fracture of the fracture zone 210.

[0041] In some embodiments, the width of the first protrusion 240 is smaller than the width of the fracture zone 210, thereby ensuring that the first protrusion 240 is unlikely to cause an increase in the width at the minimum width position of the fracture zone 210, so that the fracture zone 210 can break under the action of a preset air pressure.

[0042] In some embodiments, the pressure relief port 110 is configured as an annular shape, which divides the cover plate 10 into a first plate 120 and a second plate 130. In this case, the first protrusion 240 is also configured as an annular shape. The first protrusion 240 can provide insulation between the first plate 120 and the second plate 130.

[0043] As shown in Figure 3, in some embodiments, the height of the first protrusion 240 is H1, and the height of the pressure relief port 110 is H2, satisfying: H1≤H2.

[0044] It is understandable that the height of the first protrusion 240 is less than or equal to the height of the pressure relief port 110 to prevent the first protrusion 240 from passing through the pressure relief port 110 and affecting the aesthetics and pressure relief effect. If the height of the first protrusion 240 is greater than the height of the pressure relief port 110, the first protrusion 240 will protrude from the surface of the cover plate 10, which will affect the aesthetics of the cover plate 10. In addition, when the fracture zone 210 below breaks, the first protrusion 240 may continue to seal the pressure relief port 110, affecting the pressure relief effect.

[0045] In some embodiments, the height of the first protrusion 240 is less than the height of the pressure relief port 110, and the portion of the pressure relief port 110 that extends beyond the first protrusion 240 can be configured to be gradually widened.

[0046] Referring to Figure 2, in some embodiments, the plastic part 20 is configured with a second protrusion 250 protruding in a direction away from the cover plate 10. The second protrusion 250 is configured to abut against the electrode assembly, or the second protrusion 250 is configured to be spaced apart from the electrode assembly.

[0047] Understandably, by providing a second protrusion 250 on the side of the plastic part 20 away from the cover plate 10, and having the second protrusion 250 abut against the electrode assembly, the second protrusion 250 can support the electrode assembly and prevent it from arching upwards due to impact. Alternatively, the second protrusion 250 can be spaced apart from the electrode assembly to reduce the degree to which the electrode assembly arches upwards due to impact.

[0048] In some embodiments, the first protrusion 240 and the second protrusion 250 are both integrally formed on the plastic part 20. For example, the first protrusion 240, the second protrusion 250 and the plastic part 20 are integrally injection molded.

[0049] Referring to Figure 2, in some embodiments, the second protrusion 250 includes a first protrusion 2510 and a second protrusion 2520 spaced apart on opposite sides of the fracture region 210. The first protrusion 2510, the fracture region 210, and the second protrusion 2520 enclose a gas chamber 2530. The gas chamber 2530 is configured to contain gas generated by the electrode assembly.

[0050] It is understandable that a small amount of gas may be generated during normal battery charging and discharging. Alternatively, if the battery is only slightly damaged and less gas is generated, this gas can be contained within the gas chamber 2530 to provide space for the gas. As the gas gradually increases and the gas pressure increases, it can break through the fracture zone 210 of the plastic part 20 to achieve pressure relief.

[0051] In some embodiments, the pressure relief port 110 is configured as an annular shape, and the fracture zone 210 is also configured as an annular shape, so both the first protrusion 2510 and the second protrusion 2520 are configured as annular shapes. Thus, an annular air chamber 2530 can be formed.

[0052] In some embodiments, the cover plate 10 is configured to be subjected to internal air pressure of the battery cell and deform along the pressure relief port 110 after the fracture zone 210 is fractured.

[0053] It is understandable that after the fracture zone 210 breaks, the cover plate 10 deforms along the pressure relief port 110 under the action of the internal air pressure of the battery cell, which can increase the opening size of the pressure relief port 110 and make it easier to release pressure quickly.

[0054] It should be noted that the deformation of the cover plate 10 along the pressure relief port 110 includes: bending the cover plate 10 in a direction away from the electrode assembly corresponding to the extension area along the pressure relief port 110. Alternatively, the cover plate 10 may break into two parts along the pressure relief port 110, and the portion of the cover plate 10 located inside the pressure relief port 110 may separate from the portion of the cover plate 10 located outside the pressure relief port 110 under air pressure. This causes at least a partial detachment of the cover plate 10, thereby increasing the opening size of the pressure relief port 110. Furthermore, when the terminal assembly 30 is disposed in the area corresponding to the detached portion of the cover plate 10, the terminal assembly 30 can also be detached from the top cover assembly to cut off the connection between the terminal assembly 30 and the current collector 50, thus achieving power disconnection.

[0055] In some embodiments, the pressure relief port 110 is configured as an arc-shaped opening. The central angle corresponding to the arc-shaped opening is β, which satisfies: 180°≤β≤360°.

[0056] It is understood that the cover plate 10 can only be bent away from the electrode assembly along the extension area of ​​the pressure relief port 110 when the central angle corresponding to the pressure relief port 110 is greater than or equal to 180°, ensuring that the cover plate 10 can deform. In this embodiment, the central angle corresponding to the arc-shaped opening can be set to 360° to form an annular pressure relief port 110. When the cover plate 10 is subjected to the internal air pressure of the battery cell, the area of ​​the cover plate 10 located inside the arc-shaped opening can be pushed out by the air pressure and fall off, thereby expanding the opening size of the pressure relief port 110. Furthermore, when the terminal assembly 30 is disposed in the area corresponding to the part of the cover plate 10 that has fallen off, the terminal assembly 30 can also be detached from the top cover assembly to cut off the connection between the terminal assembly 30 and the current collector 50, thereby achieving power disconnection.

[0057] In some embodiments, the pressure relief port 110 may also be configured in other shapes. For example, the pressure relief port 110 may be configured as an elliptical opening, a square opening, etc. It is necessary to ensure that the pressure relief port 110 can relieve pressure and that the cover plate 10 can be bent or detached along the extension area of ​​the pressure relief port 110.

[0058] As shown in Figure 1, in some embodiments, a terminal assembly 30 is connected to the plastic part 20. A cover plate 10 is provided on the periphery of the terminal assembly 30. A pressure relief port 110 extends along the periphery of the terminal assembly 30. The terminal assembly 30 is configured to move away from the electrode assembly after being subjected to internal air pressure within the battery cell, and to separate from the current collector 50 of the battery cell after breaking at the fracture zone 210.

[0059] Understandably, the terminal assembly 30 is configured to connect to the current collector 50 to provide external power. The cover plate 10 is located around the periphery of the terminal assembly 30, and the pressure relief port 110 extends along the circumference of the terminal assembly 30. Under the action of internal air pressure, the cover plate 10 deforms along the pressure relief port 110. When the cover plate 10 bends away from the electrode assembly, it can also move the terminal assembly 30 away from the electrode assembly, allowing the terminal assembly 30 to separate from the current collector 50 after breaking in the fracture zone 210. When the cover plate 10 detaches away from the electrode assembly, it can also move the terminal assembly 30 away from the electrode assembly, allowing the terminal assembly 30 to separate from the current collector 50 after breaking in the fracture zone 210.

[0060] In some embodiments, the plastic part 20 is injection molded onto the terminal assembly 30 and the cover plate 10.

[0061] It is understood that both the terminal assembly 30 and the cover plate 10 are metal parts. Injecting the plastic part 20 onto the terminal assembly 30 and the cover plate 10 ensures a reliable connection between the three and facilitates the manufacturing of the top cover assembly. For example, before injection molding the plastic part 20, both the terminal assembly 30 and the cover plate 10 can be placed in the injection mold. After injection molding, the plastic part 20 directly connects to the terminal assembly 30 and the cover plate 10.

[0062] As shown in Figure 2, in some embodiments, the cover plate 10 includes a first plate 120 and a second plate 130. The first plate 120 is disposed around the periphery of the terminal assembly 30. The first plate 120 is connected to the plastic part 20. The second plate 130 is disposed around the periphery of the first plate 120. The second plate 130 is spaced apart from the first plate 120 and forms a pressure relief port 110. The second plate 130 is connected to the plastic part 20. The first plate 120 is configured such that, after being subjected to internal air pressure, it separates from the first protrusion 240 of the plastic part 20 at the position of the pressure relief port 110, and after breaking in the fracture zone 210, it moves away from the electrode assembly.

[0063] As shown in Figures 1 and 2, both the first plate 120 and the second plate 130 are annular. The outer diameter of the first plate 120 is smaller than the inner diameter of the second plate 130, so that the first plate 120 and the second plate 130 are spaced apart to form an annular pressure relief port 110. When the cover plate 10 is subjected to internal air pressure from the battery cell, the first plate 120 can separate from the first protrusion 240 of the plastic part 20 along the extension direction of the pressure relief port 110, achieving initial separation of the cover plate 10 from the plastic part 20. After the fracture zone 210 breaks due to continuous air pressure, the first plate 120 will move away from the electrode assembly, so that the first plate 120 detaches from the top cover assembly. Since the first plate 120 is arranged around the periphery of the terminal assembly 30, the detachment of the first plate 120 from the top cover assembly can cause the terminal assembly 30 to detach, thereby separating the connection between the terminal assembly 30 and the current collector 50 and achieving power disconnection.

[0064] Referring to Figure 2, in some embodiments, the plastic part 20 includes a main body 260, a first connecting portion 270, and a second connecting portion 280. The main body 260 has a mounting channel 2610, and the terminal assembly 30 is disposed within the mounting channel 2610. The first connecting portion 270 is angularly connected to the outer peripheral surface of the main body 260. The second connecting portion 280 is angularly connected to the outer peripheral surface of the main body 260. A fracture zone 210 is located in the second connecting portion 280. The first connecting portion 270 and the second connecting portion 280 are spaced apart, and the first connecting portion 270, the main body 260, and the second connecting portion 280 surround to form a first slot 2810. At least a portion of the first plate 120 is engaged in the first slot 2810.

[0065] Understandably, the main body 260 forms an mounting channel 2610 to connect the terminal assembly 30. The first connecting portion 270, the second connecting portion 280, and the first retaining groove 2810 formed on the outer surface of the main body 260 can be configured to connect the first plate 120. After the plastic part 20 and the first plate 120 are injection molded together, it can be ensured that the first plate 120 is stably and reliably engaged in the first retaining groove 2810 and will not fall off.

[0066] In some embodiments, the first connecting portion 270 and the second connecting portion 280 are arranged in parallel, and both the first connecting portion 270 and the second connecting portion 280 are perpendicular to the outer peripheral surface of the main body portion 260.

[0067] It should be noted that the fracture zone 210 is located in the second connecting part 280.

[0068] Referring to Figure 2, in some embodiments, the plastic part 20 further includes a bent portion 290. The bent portion 290 is connected to the end of the first connecting portion 270 away from the main body portion 260. The bent portion 290 extends away from the second connecting portion 280 and bends towards the terminal assembly 30. The bent portion 290 and the first connecting portion 270 together form a second slot 2910. The edge of the terminal assembly 30 is provided with a snap-fit ​​portion 310, which snaps into the second slot 2910.

[0069] It is understood that a second slot 2910 is formed based on the bending portion 290 and the first connecting portion 270 to engage the engaging portion 310 at the edge of the terminal assembly 30, thereby achieving a reliable connection between the terminal assembly 30 and the plastic part 20. When the top cover assembly is injection molded, the area of ​​the first plate 120, the main body 260, the terminal assembly 30, the first connecting portion 270, and the second connecting portion 280 located inside the fracture zone 210 will form an integral structure. This integral structure can detach entirely under internal air pressure.

[0070] In some embodiments, the main body 260, the first connecting part 270, the second connecting part 280, and the bending part 290 are integrally injection molded.

[0071] As shown in Figures 4 and 5, the top cover structure in this embodiment of the application has at least the following two pressure relief methods.

[0072] Method 1: When the top cover assembly is subjected to gas inside the battery cell, the gas first acts on the terminal assembly 30, causing it to move away from the electrode assembly. At this time, the first plate 120 and the plastic part 20 first separate. When the gas pressure reaches the opening value of the explosion-proof valve, the fracture zone 210 of the plastic part 20 breaks, and pressure is released from the pressure relief port 110. After the fracture zone 210 is completely broken, the terminal assembly 30, the first plate 120, and the portion of the plastic part 20 located inside the fracture zone 210 will be completely ejected, so that the terminal assembly 30 is completely separated from the current collector 50, achieving power disconnection. This ensures the safety of the battery cell.

[0073] Method 2: When the top cover assembly is subjected to gas inside the battery cell, the gas first acts on the terminal assembly 30, causing it to move away from the electrode assembly. At this time, both the first plate 120 and the second plate 130 peel off from the plastic part 20. Some of the gas can be depressurized at the connection between the second plate 130 and the housing 40. When the gas pressure reaches the opening value of the explosion-proof valve, the fracture zone 210 of the plastic part 20 breaks, and pressure is released from the pressure relief port 110. After the fracture zone 210 is completely broken, the terminal assembly 30, the first plate 120, and the portion of the plastic part 20 located inside the fracture zone 210 will be completely ejected, so that the terminal assembly 30 is completely separated from the current collector 50, achieving power disconnection. This ensures the safety of the battery cell.

[0074] The top cover assembly in this embodiment can be used to achieve pressure relief using method one.

[0075] This application also provides a single battery cell. The single battery cell includes the top cover assembly as described in the foregoing embodiments.

[0076] In this embodiment, by forming a fracture zone 210 on the plastic part 20 and a pressure relief port 110 on the cover plate 10, the two are combined to form an explosion-proof valve structure. This allows the explosion-proof valve structure to be formed on the top cover assembly without stamping or welding. Furthermore, the plastic part 20 can be injection molded, which allows for precise control of the thickness of the fracture zone 210, facilitating control of the opening force of the explosion-proof valve, ensuring the stability of the opening force, and improving the safety of the individual battery cell.

[0077] This application also provides a battery pack. The battery pack includes individual battery cells as described in the foregoing embodiments.

[0078] In this embodiment, by forming a fracture zone 210 on the plastic part 20 and a pressure relief port 110 on the cover plate 10, the two are combined to form an explosion-proof valve structure. This allows the explosion-proof valve structure to be formed on the top cover assembly without stamping or welding. Furthermore, the plastic part 20 can be injection molded, which allows for precise control of the thickness of the fracture zone 210, facilitating control of the opening force of the explosion-proof valve, ensuring the stability of the opening force, and improving the safety of the battery pack.

Claims

1. A top cover assembly applied to a battery cell, the battery cell including an electrode assembly, the top cover assembly comprising: The cover plate (10) is equipped with a pressure relief port (110); A plastic part (20) is connected to the cover plate (10) on the side near the electrode assembly. The plastic part (20) has a fracture zone (210) located near the pressure relief port (110). The fracture zone (210) is configured to fracture under the action of internal air pressure of the battery cell.

2. The top cover assembly according to claim 1, wherein, Along the height direction of the cell, the projection of the fracture zone (210) at least partially covers the pressure relief port (110).

3. The top cover assembly according to claim 1 or 2, wherein, The plastic part (20) is injection molded onto the cover plate (10).

4. The top cover assembly according to any one of claims 1 to 3, wherein, Along the direction from the edge of the fracture zone (210) to the central axis (220) of the fracture zone (210), at least a portion of the fracture zone (210) has a decreasing thickness.

5. The top cover assembly according to claim 4, wherein, The minimum thickness of the fracture zone (210) is D, which satisfies: 0.1 mm ≤ D ≤ 0.8 mm.

6. The top cover assembly according to any one of claims 1 to 5, wherein, A groove (230) is formed on the side of the plastic part (20) away from the cover plate (10), and the fracture zone (210) is located on the plastic part (20) corresponding to the groove (230).

7. The top cover assembly according to any one of claims 1 to 6, wherein, The plastic part (20) is constructed with a first protrusion (240) protruding toward the cover plate (10), and the first protrusion (240) is engaged with the pressure relief port (110).

8. The top cover assembly according to claim 7, wherein, The height of the first protrusion (240) is H1, and the height of the pressure relief port (110) is H2, satisfying: H1≤H2.

9. The top cover assembly according to any one of claims 1 to 8, wherein, The plastic part (20) is configured to have a second protrusion (250) protruding in a direction away from the cover plate (10), the second protrusion (250) being configured to abut against the electrode assembly, or to be spaced apart from the electrode assembly.

10. The top cover assembly according to claim 9, wherein, The second protrusion (250) includes a first protrusion (2510) and a second protrusion (2520) spaced apart on opposite sides of the fracture zone (210). The first protrusion (2510), the fracture zone (210) and the second protrusion (2520) surround and form a gas chamber (2530), which is configured to contain the gas generated by the electrode assembly.

11. The top cover assembly according to any one of claims 1 to 10, wherein, The cover plate (10) is configured to be subjected to the internal air pressure of the battery cell and deform along the pressure relief port (110) after the fracture zone (210) is broken.

12. The top cover assembly according to claim 11, wherein, The pressure relief port (110) is configured as an arc-shaped opening, and the central angle corresponding to the arc-shaped opening is β, which satisfies: 180°≤β≤360°.

13. The top cover assembly according to any one of claims 1 to 12, wherein, A terminal assembly (30) is connected to the plastic part (20), and a cover plate (10) is provided on the periphery of the terminal assembly (30). The pressure relief port (110) extends along the periphery of the terminal assembly (30). The terminal assembly (30) is configured to move away from the electrode assembly after being subjected to the internal air pressure of the battery cell, and separate from the current collector (50) of the battery cell after breaking in the fracture zone (210).

14. The top cover assembly according to claim 13, wherein, The plastic part (20) is injection molded onto the terminal assembly (30) and the cover plate (10).

15. The top cover assembly according to claim 13 or 14, wherein, The cover plate (10) includes: A first plate (120) is arranged around the periphery of the terminal assembly (30), and the first plate (120) is connected to the plastic part (20); The second plate (130) is arranged around the periphery of the first plate (120). The second plate (130) is spaced apart from the first plate (120) and forms the pressure relief port (110). The second plate (130) is connected to the plastic part (20). The first plate (120) is configured to separate from the first protrusion (240) of the plastic part (20) along the pressure relief port (110) after being subjected to the internal air pressure of the battery cell, and to move away from the electrode assembly after breaking in the fracture zone (210).

16. The top cover assembly according to claim 15, wherein, The plastic part (20) includes: The main body (260) has a mounting channel (2610), and the terminal assembly (30) is disposed in the mounting channel (2610); The first connecting part (270) is angularly connected to the outer peripheral surface of the main body part (260); The second connecting part (280) is angularly connected to the outer peripheral surface of the main body part (260), and the fracture area (210) is located in the second connecting part (280). The first connecting part (270) and the second connecting part (280) are spaced apart, and the first connecting part (270), the main body part (260) and the second connecting part (280) surround to form a first slot (2810). At least a portion of the first plate (120) is engaged in the first slot (2810).

17. The top cover assembly according to claim 16, wherein, The plastic part (20) also includes: A bent portion (290) is connected to one end of the first connecting portion (270) away from the main body portion (260). The bent portion (290) extends in a direction away from the second connecting portion (280) and bends in a direction toward the terminal assembly (30). The bent portion (290) and the first connecting portion (270) together form a second slot (2910). The terminal assembly (30) has a snap-fit ​​portion (310) on its edge, which snaps into the second slot (2910).

18. A single battery cell, comprising a top cover assembly as described in any one of claims 1 to 17.

19. A battery pack comprising the single battery cell as described in claim 18.

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