Top cover assembly, single battery cell and battery pack

Abstract

The utility model relates to the technical field of batteries, and provides a top cover assembly, a single battery cell and a battery pack. The top cover assembly comprises a plastic part and a cover plate. A pressure relief opening is formed in the cover plate. The plastic part is connected with the side, close to the electrode assembly, of the cover plate. The plastic part has a fracture area. The fracture area is arranged close to the pressure relief opening. And the fracture area is configured to be fractured under the action of air pressure in the battery cell. Therefore, the anti-explosion valve structure can be formed on the top cover assembly without a stamping or welding mode, and the stability of the opening force of the anti-explosion valve can be ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery technology field, concretely relates to a top cover subassembly, single battery and battery package. BACKGROUND

[0002] In the related art, the battery explosion-proof valve is usually formed on the top cover subassembly by stamping or welding. For the explosion-proof valve formed on the top cover subassembly by stamping, the stamping will damage the surface plating layer, resulting in metal exposure and poor corrosion resistance. To improve the corrosion resistance, nickel plating is usually performed on the surface, and surface pickling is performed after the nickel plating. The nickel plating will strengthen the strength of the notch of the explosion-proof valve, and the pickling will cause the notch to corrode to some extent. Thus, the strength of each notch is different, resulting in poor notch stability and unstable opening force of the explosion-proof valve. For the explosion-proof valve formed on the top cover subassembly by welding, the welding will cause defects in the top cover subassembly, reducing the safety thereof. Moreover, the welding method is not applicable to all metals, and the applicability thereof is low. SUMMARY

[0003] Embodiments of the utility model provide a top cover subassembly, single battery and battery package. A fracture zone is formed on a plastic part, a pressure relief port is formed on a cover plate, and an explosion-proof valve structure is formed by cooperation of the two. The explosion-proof valve structure can be formed on the top cover subassembly without stamping or welding. Meanwhile, the plastic part can be injection molded, and the thickness of the fracture zone can be well controlled to facilitate control of the opening force of the explosion-proof valve and ensure the stability of the opening force of the explosion-proof valve.

[0004] In a first aspect, embodiments of the utility model provide a top cover subassembly applied to a battery cell. The battery cell includes an electrode assembly, and the top cover subassembly includes:

[0005] a cover plate configured with a pressure relief port;

[0006] a plastic part connected to one side of the cover plate close to the electrode assembly, the plastic part having a fracture zone close to the pressure relief port, the fracture zone being configured to break under the action of internal gas pressure of the battery cell.

[0007] In an embodiment, a projection of the fracture zone covers at least part of the pressure relief port in the height direction of the battery cell.

[0008] In an embodiment, the plastic part is injection molded on the cover plate.

[0009] In an embodiment, the thickness of at least part of the fracture zone decreases in the direction from the edge of the fracture zone to the central axis of the fracture zone.

[0010] In an embodiment, the minimum thickness of the fracture zone is D, satisfying 0.1 millimeter ≤ D ≤ 0.8 millimeter.

[0011] In an embodiment, the plastic member is formed with a groove away from one side of the cover plate, and the fracture zone is located at a position corresponding to the groove of the plastic member.

[0012] In an embodiment, the plastic member is configured with a first protruding portion protruding towards the cover plate, and the first protruding portion is clamped to the pressure relief port.

[0013] In an embodiment, the height of the first protruding portion is H1, and the height of the pressure relief port is H2, and H1≤H2 is satisfied.

[0014] In an embodiment, the plastic member is configured with a second protruding portion protruding away from the cover plate, and the second protruding portion is configured to abut the electrode assembly, or the second protruding portion is configured to be spaced apart from the electrode assembly.

[0015] In an embodiment, the second protruding portion includes a first protruding segment and a second protruding segment spaced apart on opposite sides of the fracture zone, and the first protruding segment, the fracture zone, and the second protruding segment form an air chamber configured to accommodate gas generated by the electrode assembly.

[0016] In an embodiment, the cover plate is configured to be deformed along the pressure relief port under the action of the internal gas pressure of the battery cell after the fracture of the fracture zone.

[0017] In an embodiment, the pressure relief port is provided as an arc-shaped opening, and the central angle corresponding to the arc-shaped opening is β, and 180°≤β≤360° is satisfied.

[0018] In an embodiment, a terminal assembly is connected to the plastic member, and the cover plate is arranged at the periphery of the terminal assembly, wherein the pressure relief port extends along the peripheral side of the terminal assembly, and the terminal assembly is configured to move away from the electrode assembly under the action of the internal gas pressure of the battery cell, and to be separated from the current collector of the battery cell after the fracture of the fracture zone.

[0019] In an embodiment, the plastic member is injection molded on the terminal assembly and the cover plate.

[0020] In an embodiment, the cover plate includes:

[0021] a first plate body arranged at the periphery of the terminal assembly, and the first plate body is connected to the plastic member;

[0022] a second plate body arranged at the periphery of the first plate body, and the second plate body is spaced apart from the first plate body and forms the pressure relief port, and the second plate body is connected to the plastic member;

[0023] The first plate body is configured to be separated from the first protruding part of the plastic piece at a position along the pressure relief opening under the action of the internal gas pressure of the battery cell, and to move away from the electrode assembly after the fracture zone is fractured.

[0024] In an embodiment, the plastic piece comprises:

[0025] The main body part has a mounting channel, and the terminal assembly is arranged in the mounting channel.

[0026] The first connecting part is connected to the outer circumferential surface of the main body part at an angle.

[0027] The second connecting part is connected to the outer circumferential surface of the main body part at an angle, and the fracture zone is located in the second connecting part.

[0028] In an embodiment, the plastic piece further comprises:

[0029] The bending part is connected to one end of the first connecting part away from the main body part, extends away from the second connecting part, and bends towards the terminal assembly, and the bending part and the first connecting part enclose a second clamping groove.

[0030] The edge of the terminal assembly is configured with a clamping part, and the clamping part is clamped in the second clamping groove.

[0031] In a second aspect, the embodiments of the utility model provide a single battery cell, which comprises the top cover assembly as described above.

[0032] In a third aspect, the embodiments of the utility model provide a battery pack, which comprises the single battery cell as described above.

[0033] The embodiments of the utility model have the following beneficial effects:

[0034] In the embodiments of the utility model, the fracture zone is formed on the plastic piece, and the pressure relief opening is formed on the cover plate, and the explosion-proof valve structure is formed by cooperation of the two, so that the explosion-proof valve structure can be formed on the top cover assembly without stamping or welding. Meanwhile, the plastic piece can be formed by injection molding, and the thickness of the fracture zone can be well controlled to facilitate control of the opening force of the explosion-proof valve and ensure the stability of the opening force of the explosion-proof valve. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0036] Figure 1 is a perspective view of the top cover assembly provided by the embodiment of the present application;

[0037] Figure 2 is a sectional view of the top cover assembly provided by the embodiment of the present application;

[0038] Figure 3 is Figure 2 is an enlarged view of part A in the figure;

[0039] Figure 4 is one of the pressure relief state schematic views of the top cover assembly provided by the embodiment of the present application;

[0040] Figure 5 is another of the pressure relief state schematic views of the top cover assembly provided by the embodiment of the present application.

[0041] Reference signs:

[0042] 10-cover plate, 110-pressure relief port, 120-first plate body, 130-second plate body, 20-plastic part, 210-fracture zone, 220-central axis, 230-groove, 240-first protruding part, 250-second protruding part, 2510-first protruding section, 2520-second protruding section, 2530-air chamber, 260-main body part, 2610-mounting channel, 270-first connecting part, 280-second connecting part, 2810-first clamping groove, 290-bent part, 2910-second clamping groove, 30-terminal assembly, 310-clamping part, 40-housing, 50-current collecting part. DETAILED DESCRIPTION

[0043] Clearly, the described embodiments are merely a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative efforts under the premise that no creative efforts are made, belong to the scope of protection of the present application. In addition, it should be understood that the specific embodiments described herein are merely used to illustrate and explain the present application, and are not used to limit the present application. In the present application, the orientation words such as "upper" and "lower" generally refer to the upper and lower of the device in the actual use or working state, and specifically refer to the direction of the drawing in the accompanying drawings; and "inner" and "outer" refer to the contour of the device.

[0044] As shown in the Figures 1 to 5 embodiments of the present application provide a top cover assembly. The 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. The cover plate 10 is configured with a pressure relief port 110. The plastic part 20 is connected to the side of the cover plate 10 close to the electrode assembly. The plastic part 20 has a fracture zone 210. The fracture zone 210 is arranged close to the pressure relief port 110. The fracture zone 210 is configured to be broken after being affected by the internal gas pressure of the battery cell.

[0045] In the embodiments of the present application, by forming the fracture zone 210 on the plastic part 20 and the pressure relief port 110 on the cover plate 10, the explosion-proof valve structure is formed by cooperation of the two. The explosion-proof valve structure can be formed on the top cover assembly without stamping or welding. At the same time, the plastic part 20 can be injection molded, and the thickness of the fracture zone 210 can be well controlled to facilitate the control of the opening force of the explosion-proof valve and ensure the stability of the opening force of the explosion-proof valve.

[0046] It can be understood that when the electrode assembly of the battery cell is pierced or damaged in other ways, a large amount of gas will be generated. If the gas continues to accumulate in the shell 40 of the battery cell, it will cause serious safety hazards. In the embodiments of the present application, the fracture zone 210 is formed on the plastic part 20. When the internal gas pressure of the shell 40 reaches a certain degree, the internal gas pressure of the shell 40 can make the fracture zone 210 break. After the fracture zone 210 breaks, the gas can be discharged from the fracture of the plastic part 20 and the pressure relief port 110 of the cover plate 10.

[0047] 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.

[0048] 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.

[0049] like Figure 2 As shown, 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.

[0050] 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.

[0051] In some embodiments, the projection of the fracture zone 210 along the height direction of the cell exactly covers the pressure relief port 110.

[0052] 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.

[0053] In some embodiments, the plastic part 20 is injection molded onto the cover plate 10.

[0054] 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.

[0055] like Figure 3 As shown, 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.

[0056] It can be understood that at least part of the thickness of the fracture zone 210 decreases, and when it decreases to the position of the minimum thickness, the position can be broken under the action of air pressure. In the embodiments of the present application, the fracture zone 210 is arranged to have at least part of the thickness decreasing, so that the thickness of the fracture zone 210 is less than the thickness of other regions of the plastic part 20, and the fracture zone 210 can be broken at the position of the fracture zone 210 under the action of air pressure.

[0057] As shown in Figure 3 , along the direction from the edge of the fracture zone 210 to the central axis 220 of the fracture zone 210, the thickness of the fracture zone 210 first decreases and then remains unchanged. The region with the unchanged thickness is the minimum thickness region of the fracture zone 210. Under the action of the internal air pressure of the battery cell, the minimum thickness position of the fracture zone 210 will be broken.

[0058] In some embodiments, the thickness of at least part of the fracture zone 210 can decrease linearly or exponentially.

[0059] In some embodiments, a slope, arc or other structure can be formed on the side of the fracture zone 210 close to the cover plate 10, so that the thickness of the fracture zone 210 decreases. Alternatively, a slope, arc or other structure can be formed on the side of the fracture zone 210 close to the electrode assembly, so that the thickness of the fracture zone 210 decreases. Alternatively, a slope, arc or other structure can be formed on both sides of the fracture zone 210, so that the thickness of the fracture zone 210 decreases.

[0060] Please continue to refer to Figure 3 In some embodiments, the minimum thickness of the fracture zone 210 is D, which satisfies: 0.1 millimeter≤D≤0.8 millimeter.

[0061] It can be understood that under the action of the internal air pressure of the battery cell, the minimum thickness position of the fracture zone 210 will be broken. The fracture zone 210 can select the value of the minimum thickness of the fracture zone 210 based on the opening value of the top cover assembly explosion-proof valve. The minimum thickness value of the fracture zone 210 is positively correlated with the opening value of the top cover assembly explosion-proof valve. Specifically, the greater the opening value of the top cover assembly explosion-proof valve, the greater the minimum thickness value of the fracture zone 210; the smaller the opening value of the top cover assembly explosion-proof valve, the smaller the minimum thickness value of the fracture zone 210.

[0062] 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.

[0063] 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.

[0064] Please continue reading. 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.

[0065] 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.

[0066] 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.

[0067] like Figure 2 and Figure 3 As shown, in some embodiments, the plastic part 20 is configured with a first protrusion 240 protruding toward the cover plate 10. The first protrusion 240 engages with the pressure relief port 110.

[0068] 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 will not affect the fracture of the fracture zone 210.

[0069] 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 does not 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.

[0070] 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.

[0071] like Figure 3 As shown, 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.

[0072] 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.

[0073] 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.

[0074] Please continue reading. 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.

[0075] 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.

[0076] 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.

[0077] Please continue reading.Figure 2 In some embodiments, the second protrusion 250 comprises a first protruding section 2510 and a second protruding section 2520, which are arranged on opposite sides of the fracture zone 210. The first protruding section 2510, the fracture zone 210 and the second protruding section 2520 form a gas chamber 2530. The gas chamber 2530 is configured to accommodate the gas generated by the electrode assembly.

[0078] It can be understood that a small amount of gas can also be generated during the normal charging and discharging process of the battery. Alternatively, when the battery is slightly damaged and generates less gas, the part of the gas can be accommodated in the gas chamber 2530 to provide space for accommodating the gas. When the gas gradually increases and the gas pressure increases, the fracture zone 210 of the plastic part 20 can be broken to achieve pressure relief.

[0079] In some embodiments, the pressure relief port 110 is arranged in a circular ring shape, and the fracture zone 210 is also arranged in a circular ring shape, and the first protruding section 2510 and the second protruding section 2520 are also arranged in a circular ring shape. Thus, the gas chamber 2530 in a circular ring shape can be formed.

[0080] In some embodiments, the cover plate 10 is configured to be deformed along the pressure relief port 110 under the action of the internal gas pressure of the battery cell after the fracture zone 210 is broken.

[0081] It can be understood that after the fracture zone 210 is broken, the cover plate 10 is deformed along the pressure relief port 110 under the action of the internal gas pressure of the battery cell, and the opening size of the pressure relief port 110 can be expanded, which is more convenient for rapid pressure relief.

[0082] It should be noted that the deformation of the cover plate 10 along the pressure relief port 110 includes that the extension area of the cover plate 10 corresponding to the pressure relief port 110 is bent away from the electrode assembly. Alternatively, the cover plate 10 is broken into two parts along the pressure relief port 110, and the part of the cover plate 10 inside the pressure relief port 110 is separated from the part of the cover plate 10 outside the pressure relief port 110 under the action of the gas pressure. Thus, the cover plate 10 is at least partially separated to expand the opening size of the pressure relief port 110. Furthermore, when the terminal assembly 30 is arranged in the area corresponding to the separated part of the cover plate 10, the terminal assembly 30 can also be separated from the top cover assembly to cut off the connection between the terminal assembly 30 and the current collector 50, thereby achieving power-off.

[0083] In some embodiments, the pressure relief port 110 is arranged as an arc-shaped opening. The central angle of the arc-shaped opening is β, which satisfies: 180°≤β≤360°.

[0084] 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 is preferably 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.

[0085] 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.

[0086] like Figure 1 As shown, 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.

[0087] It is understood that the terminal assembly 30 is used to connect the current collector 50 to enable external power supply. 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, thus allowing the terminal assembly 30 to separate from the current collector 50 after breaking in the fracture zone 210. When the cover plate 10 falls off away from the electrode assembly, it can also move the terminal assembly 30 away from the electrode assembly, thus allowing the terminal assembly 30 to separate from the current collector 50 after breaking in the fracture zone 210.

[0088] In some embodiments, the plastic part 20 is injection molded onto the terminal assembly 30 and the cover plate 10.

[0089] It can be understood that the terminal assembly 30 and the cover plate 10 are both metal pieces. The plastic piece 20 is injection molded on the terminal assembly 30 and the cover plate 10, which ensures reliable connection of the three and facilitates manufacturing of the top cover assembly. For example, the terminal assembly 30 and the cover plate 10 can be placed in the injection mold before the plastic piece 20 is injection molded. After the plastic piece 20 is injection molded, the plastic piece 20 is directly connected with the terminal assembly 30 and the cover plate 10.

[0090] As shown in Figure 2 In some embodiments, the cover plate 10 includes a first plate body 120 and a second plate body 130. The first plate body 120 is annularly arranged around the periphery of the terminal assembly 30. The first plate body 120 is connected with the plastic piece 20. The second plate body 130 is annularly arranged around the periphery of the first plate body 120. The second plate body 130 is spaced apart from the first plate body 120 and forms the pressure relief port 110. The second plate body 130 is connected with the plastic piece 20. The first plate body 120 is configured to be separated from the first protruding portion 240 of the plastic piece 20 at the position of the pressure relief port 110 after the cover plate 10 is subjected to the internal pressure of the battery cell, and to move away from the electrode assembly after the fracture zone 210 is broken.

[0091] As shown in Figure 1 and Figure 2 The first plate body 120 and the second plate body 130 are both arranged in a circular ring shape. The outer diameter of the first plate body 120 is smaller than the inner diameter of the second plate body 130, so that the first plate body 120 and the second plate body 130 are spaced apart to form a circular ring-shaped pressure relief port 110. When the cover plate 10 is subjected to the internal pressure of the battery cell, the first plate body 120 can be separated from the first protruding portion 240 of the plastic piece 20 along the extension direction of the pressure relief port 110, thereby achieving initial peeling of the cover plate 10 from the plastic piece 20. After the fracture zone 210 is broken due to the continuous action of the pressure, the first plate body 120 will move away from the electrode assembly, so that the first plate body 120 is separated from the top cover assembly. Based on the fact that the first plate body 120 is annularly arranged around the periphery of the terminal assembly 30, the first plate body 120 is separated from the top cover assembly, so that the terminal assembly 30 is separated from the current collecting piece 50, thereby achieving power-off.

[0092] Please continue to refer to Figure 2In some embodiments, the plastic part 20 comprises a main body portion 260, a first connecting portion 270 and a second connecting portion 280. The main body portion 260 has a mounting channel 2610, and the terminal assembly 30 is arranged in the mounting channel 2610. The first connecting portion 270 is connected to the outer circumferential surface of the main body portion 260 at an angle. The second connecting portion 280 is connected to the outer circumferential surface of the main body portion 260 at an angle. The fracture zone 210 is located in the second connecting portion 280. The first connecting portion 270 is spaced apart from the second connecting portion 280, and the first connecting portion 270, the main body portion 260 and the second connecting portion 280 form a first clamping groove 2810. At least part of the first plate body 120 is clamped in the first clamping groove 2810.

[0093] It can be understood that the main body portion 260 forms the mounting channel 2610 to connect the terminal assembly 30. The first connecting portion 270, the second connecting portion 280 and the outer surface of the main body portion 260 form the first clamping groove 2810, which can be used to connect the first plate body 120. After the plastic part 20 and the first plate body 120 are injection molded and connected, it can be ensured that the first plate body 120 is stably and reliably clamped in the first clamping groove 2810 and does not fall off.

[0094] In some embodiments, the first connecting portion 270 and the second connecting portion 280 are arranged in parallel, and the first connecting portion 270 and the second connecting portion 280 are both perpendicular to the outer circumferential surface of the main body portion 260.

[0095] It should be noted that the fracture zone 210 is arranged in the second connecting portion 280.

[0096] Please continue to refer to Figure 2 In some embodiments, the plastic part 20 further comprises a bending portion 290. The bending portion 290 is connected to the end of the first connecting portion 270 away from the main body portion 260. The bending portion 290 extends away from the second connecting portion 280 and bends towards the terminal assembly 30. The bending portion 290 and the first connecting portion 270 form a second clamping groove 2910. The edge of the terminal assembly 30 is configured with a clamping portion 310, which is clamped in the second clamping groove 2910.

[0097] It can be understood that the second clamping groove 2910 is formed based on the bending portion 290 and the first connecting portion 270 to clamp the clamping portion 310 at the edge of the terminal assembly 30, thereby achieving reliable connection between the terminal assembly 30 and the plastic part 20. When the top cover assembly is injection molded, the first plate body 120, the main body portion 260, the terminal assembly 30, the first connecting portion 270 and the second connecting portion 280 in the area inside the fracture zone 210 will form an integral structure. The integral structure can be completely removed after being subjected to internal air pressure.

[0098] In some embodiments, the main body 260, the first connecting portion 270, the second connecting portion 280 and the bending portion 290 are integrally injection molded.

[0099] As shown in FIGS. 1 and 2, the top cover structure in the embodiment of the present application has at least two pressure relief modes. Figure 4 Figure 5 As shown in FIGS. 1 and 2, the top cover structure in the embodiment of the present application has at least two pressure relief modes.

[0100] Mode one: when the top cover assembly is subjected to the gas inside the battery cell, the gas will first act on the position of the terminal assembly 30, causing the terminal assembly 30 to move away from the electrode assembly. At this time, the first plate body 120 is first peeled off from the plastic part 20. When the gas pressure reaches the opening value of the explosion-proof valve, the fracture zone 210 of the plastic part 20 breaks and releases pressure from the pressure relief port 110. After the fracture zone 210 is completely broken, the terminal assembly 30, the first plate body 120 and the part of the plastic part 20 inside the fracture zone 210 will be completely flushed out, so that the terminal assembly 30 and the current collecting part 50 are completely separated, realizing power-off. Thus, the safety of the battery cell is ensured.

[0101] Mode two: when the top cover assembly is subjected to the gas inside the battery cell, the gas will first act on the position of the terminal assembly 30, causing the terminal assembly 30 to move away from the electrode assembly. At this time, the first plate body 120 and the second plate body 130 are both peeled off from the plastic part 20. A part of the gas can be released at the connection between the second plate body 130 and the shell 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 releases pressure from the pressure relief port 110. After the fracture zone 210 is completely broken, the terminal assembly 30, the first plate body 120 and the part of the plastic part 20 inside the fracture zone 210 will be completely flushed out, so that the terminal assembly 30 and the current collecting part 50 are completely separated, realizing power-off. Thus, the safety of the battery cell is ensured.

[0102] The top cover assembly in the embodiment of the present application preferably uses mode one to realize pressure relief.

[0103] The embodiment of the present application also provides a single battery cell. The single battery cell comprises the top cover assembly as in the foregoing embodiments.

[0104] In the embodiment of the present application, by forming the fracture zone 210 on the plastic part 20 and the pressure relief port 110 on the cover plate 10, and using the two to form an explosion-proof valve structure, the explosion-proof valve structure can be formed on the top cover assembly without stamping or welding. At the same time, the plastic part 20 can be injection molded, and the thickness of the fracture zone 210 can be well controlled to facilitate the control of the opening force of the explosion-proof valve, ensure the stability of the opening force of the explosion-proof valve, and improve the safety of the single battery cell.

[0105] ​The application also provides a battery pack. The battery pack comprises the single battery cell as in the foregoing embodiments.

[0106] In the embodiments of the application, the rupture zone 210 is formed on the plastic part 20, and the pressure relief port 110 is formed on the cover plate 10, and the explosion-proof valve structure is formed by cooperation of the two, so that the explosion-proof valve structure can be formed on the top cover assembly without stamping or welding. Meanwhile, the plastic part 20 can be formed by injection molding, and the thickness of the rupture zone 210 can be well controlled, so as to control the opening force of the explosion-proof valve, ensure the stability of the opening force of the explosion-proof valve, and improve the safety of the battery pack.

[0107] The embodiments of the application are described in detail above, and the principles and implementation manners of the application are described by applying specific examples; the above embodiment descriptions are only used to help understand the method of the application and its core idea; meanwhile, for those skilled in the art, the specific implementation manners and application ranges will be changed according to the idea of the application, and the content of the specification should not be understood as a limitation on the application.

Claims

1. A top cover assembly applied to a battery cell, the battery cell including an electrode assembly, characterized in that, The top cover assembly comprises: a cover plate configured with a pressure relief port; a plastic member connected to one side of the cover plate close to the electrode assembly, the plastic member having a fracture zone, the fracture zone being arranged close to the pressure relief port, the fracture zone being configured to break under the action of the internal gas pressure of the battery cell.

2. The roof assembly of claim 1, wherein, In the height direction of the battery cell, the projection of the fracture zone covers at least part of the pressure relief port.

3. The roof assembly of claim 1, wherein, The plastic member is injection molded on the cover plate.

4. The roof assembly of claim 1, wherein, In the direction from the edge of the fracture zone to the central axis of the fracture zone, the thickness of at least part of the fracture zone decreases.

5. The roof assembly of claim 4, wherein, The minimum thickness of the fracture zone is D, which satisfies: 0.1mm≤D≤0.8mm.

6. The roof assembly of claim 1, wherein, The side of the plastic member away from the cover plate is formed with a groove, and the fracture zone is located at the position of the plastic member corresponding to the groove.

7. The roof assembly of claim 1, wherein, The plastic member is configured with a first protruding part protruding towards the cover plate, and the first protruding part is clamped in the pressure relief port.

8. The roof assembly of claim 7, wherein, The height of the first protruding part is H1, and the height of the pressure relief port is H2, which satisfies: H1≤H2.

9. The roof assembly of claim 1, wherein, The plastic member is configured with a second protruding part protruding away from the cover plate, which is configured to abut against the electrode assembly or is spaced apart from the electrode assembly.

10. The roof assembly of claim 9, wherein, The second protruding part includes a first protruding segment and a second protruding segment spaced apart on opposite sides of the fracture zone, and the first protruding segment, the fracture zone and the second protruding segment form an air chamber, which is configured to accommodate the gas generated by the electrode assembly.

11. The roof assembly of any one of claims 1 to 10, wherein, The cover plate is configured to be deformed along the pressure relief port under the action of the internal gas pressure of the battery cell after the fracture of the fracture zone.

12. The roof assembly of claim 11, wherein, The pressure relief port is arranged as an arc-shaped opening, and the central angle corresponding to the arc-shaped opening is β, which satisfies: 180°≤β≤360°.

13. The roof assembly of any one of claims 1 to 10, wherein, A terminal assembly is connected to the plastic member, and the cover plate is arranged at the periphery of the terminal assembly, wherein the pressure relief port extends along the peripheral side of the terminal assembly, and the terminal assembly is configured to move away from the electrode assembly under the action of the internal gas pressure of the battery cell, and to separate from the current collector of the battery cell after the fracture of the fracture zone.

14. The roof assembly of claim 13, wherein, The plastic member is injection molded on the terminal assembly and the cover plate.

15. The roof assembly of claim 13, wherein, The cover plate comprises: a first plate body arranged at the periphery of the terminal assembly, the first plate body being connected to the plastic member; a second plate body arranged at the periphery of the first plate body, the second plate body being spaced apart from the first plate body and forming the pressure relief port, the second plate body being connected to the plastic member; wherein the first plate body is configured to separate from the first protruding part of the plastic member along the pressure relief port under the action of the internal gas pressure of the battery cell, and to move away from the electrode assembly after the fracture of the fracture zone.

16. The roof assembly of claim 15, wherein, The plastic member comprises: a main body portion having a mounting channel, the terminal assembly being arranged in the mounting channel; a first connecting portion being angularly connected to the outer peripheral surface of the main body portion; A second connecting portion is connected to the outer circumferential surface of the main body portion at an angle, and the breaking zone is located in the second connecting portion. The first connecting portion is spaced apart from the second connecting portion, and the first connecting portion, the main body portion, and the second connecting portion form a first clamping groove, and at least part of the first plate body is clamped in the first clamping groove.

17. The roof assembly of claim 16, wherein, The plastic part further comprises: A bending portion is connected to one end of the first connecting portion away from the main body portion. The bending portion extends away from the second connecting portion and bends towards the terminal assembly. The bending portion and the first connecting portion form a second clamping groove. The edge of the terminal assembly is configured with a clamping portion, and the clamping portion is clamped in the second clamping groove.

18. A monobloc cell characterized in that, A top cover assembly comprising any one of claims 1 to 17.

19. A battery pack, characterized by A single cell comprising the single cell of claim 18.

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