Anti-explosion sheet, cap assembly and cylindrical lithium battery

Abstract

The utility model provides an anti-explosion sheet, a cap assembly and a cylindrical lithium battery. The anti-explosion piece comprises an anti-explosion piece body, a notch groove combination is arranged on one side of the top face of the anti-explosion piece body, the notch groove combination comprises an annular first notch groove and a second notch groove extending linearly, the second notch groove is located in an area limited by the first notch groove, and the two ends of the second notch groove are communicated with the first notch groove. Wherein at least one of the first notch groove and the second notch groove is fractured when the internal pressure of the cylindrical lithium battery exceeds a preset value, so that the anti-explosion sheet is opened, and one of the first notch groove and the second notch groove which is fractured firstly can drive the other notch groove to be fractured. Therefore, one of the first notch groove and the second notch groove can be broken when the internal air pressure of the battery reaches a preset value, and the other notch groove can be driven to be broken, so that the opening area of the anti-explosion sheet is increased, the anti-explosion sheet can be quickly and effectively opened to release pressure, and the safety of the battery is further improved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to an explosion-proof plate, a cap assembly and a cylindrical lithium battery. Background Art

[0002] Cylindrical lithium batteries have better safety due to their uniform stress and good heat dissipation performance. However, in actual use, due to improper use, internal defects and manufacturing process, cylindrical lithium batteries may still have the safety risk of internal pressure imbalance. In order to avoid battery deformation, bulging, or even combustion or explosion, the internal pressure of the battery needs to be relieved in time.

[0003] In the related art, an explosion-proof plate is usually set in the cap assembly of a cylindrical lithium battery to cut off the current when the internal pressure of the battery is unbalanced. For example, CN220692155U discloses a lithium battery cap structure, wherein when the internal pressure of the battery increases, the gas inside the battery enters the gap between the CID orifice plate body and the explosion-proof plate body through the CID orifice plate body, pushing the explosion-proof plate body to flip, thereby breaking the welding point between the boss and the blind hole, disconnecting the battery from power, and preventing the battery from continuing to be powered on and causing danger. In addition, a circle of annular explosion-proof grooves is set around the periphery of the explosion-proof plate body, so that when the pressure inside the battery reaches a limited value, the explosion-proof groove can cause the explosion-proof plate body to rupture, so that the battery can be depressurized. However, for cylindrical batteries, the causes and locations of the internal gas generation are relatively complex. Therefore, the pressure distribution inside the battery is usually irregular. For example, in some cases, the gas pressure in the middle area of ​​the battery rises rapidly and reaches a limited value, while in other cases, the gas pressure in the edge area inside the battery rises rapidly and reaches a limited value. Therefore, it can be understood that although the explosion-proof grooves located at the periphery of the explosion-proof plate body can meet the requirement of explosion when the gas pressure in the edge area inside the battery increases and reaches a limited value, the explosion-proof grooves cannot respond and break immediately when the gas pressure in the middle area inside the battery increases and reaches a limited value. As gas continues to be generated inside the battery and the gas pressure in the edge area also reaches a limited value, the explosion-proof grooves will rupture and release the battery pressure. Therefore, this explosion-proof plate structure has certain safety hazards. Utility Model Content

[0004] To solve the above problems, an embodiment of the present application provides an explosion-proof plate. When the internal air pressure of the battery exceeds a preset value, the explosion-proof plate can be opened quickly and effectively to release the pressure, thereby improving the safety of the battery.

[0005] The present application also provides a cap assembly using the explosion-proof disk.

[0006] The present application also provides a cylindrical lithium battery using the above-mentioned cap assembly.

[0007] In a first aspect of an embodiment of the present application, a burst-proof plate is provided for a cylindrical lithium battery, comprising a burst-proof plate body, at least one side of the burst-proof plate body being provided with a groove combination, the groove combination comprising a first annular groove and a second groove extending in a straight line, the second groove being located within a region defined by the first groove, and both ends of the second groove being connected to the first groove;

[0008] Wherein, at least one of the first groove and the second groove breaks when the internal pressure of the cylindrical lithium battery exceeds a preset value, so that the explosion-proof plate opens, and the first groove and the second groove that break first can drive the other to break as well.

[0009] The explosion-proof disk according to the first aspect of the embodiment of the present application has at least the following beneficial effects:

[0010] Since the explosion-proof disk of the embodiment of the present application is provided with an annular first groove and a linear second groove on the explosion-proof disk body, and the two ends of the second groove are connected to the first groove, when the internal pressure of the battery rises sharply due to abnormal conditions such as overheating and short circuit, when the pressure value of the edge area reaches the preset value first, the first groove breaks first, and the gas inside the battery rushes out from the gap caused by the break of the first groove to release the pressure in time, and the first groove will also drive the second groove to break during the breaking process, thereby expanding the opening area of ​​the explosion-proof disk and improving the pressure relief effect; and when the pressure value of the middle area reaches the preset value first, the second groove breaks first, and the gas inside the battery rushes out from the gap caused by the break of the second groove to release the pressure in time, and the second groove will also drive the first groove to break during the breaking and opening process, thereby expanding the opening area of ​​the explosion-proof disk and improving the pressure relief effect. Therefore, when the gas pressure inside the battery exceeds the preset value, the explosion-proof disk can be opened quickly and effectively to release the pressure, thereby improving the safety of the battery.

[0011] In a possible implementation, the depth H1 of the first groove is less than the depth H2 of the second groove. By increasing the depth of the second groove, the effect of the increased thickness of the explosion-proof valve body in the middle region on the second groove can be reduced, so as to ensure that the explosion-proof valve opens smoothly at the second groove.

[0012] In a possible implementation, the depth of the middle portion of the second groove is greater than the depth of the two ends. By setting the depth of the second groove in the middle portion to be greater than the depth of the two ends, that is, the depth of the second groove is deeper in the middle portion and shallower at the two ends, the influence of the thickness step change of the explosion-proof valve body in the middle region can be reduced, so as to ensure that the explosion-proof valve is opened smoothly at the second groove.

[0013] In a possible implementation, the bottoms of the first groove and the second groove are provided with rounded corners. By providing the rounded corners at the bottoms of the first groove and the second groove, stress concentration at the bottoms of the first groove and the second groove can be reduced, thereby reducing the risk of accidental opening of the burst disk when the pressure value does not reach the preset value.

[0014] In a possible implementation manner, the radius of the rounded corners at the bottom of the first groove and the second groove is the same. The radius of the rounded corners at the bottom of the first groove and the second groove is the same, which can reduce design and manufacturing costs.

[0015] In a possible implementation, the fillet is R, which satisfies: 0.05 mm ≤ R ≤ 0.15 mm. If the radius of the fillet is too small, the stress concentration at the bottom of the first groove and the second groove cannot be effectively reduced; on the contrary, if the radius of the fillet is too large, the processing difficulty of the mold will be too large, increasing the cost.

[0016] In a possible implementation, the explosion-proof disk body is provided with a thinning portion extending in the radial direction, the first groove is arranged within the radial range where the thinning portion is located, the thickness of the thinning portion is T, the depth of the first groove is H1, and the following conditions are satisfied: 30%≤H1 / T≤60%. More preferably, the following conditions are satisfied: 40%≤H1 / T≤55%. If H1 / T is small, that is, the first groove is shallow, the first groove is not easy to break, the opening pressure will be too large, the gas inside the battery cannot be released in time, and the safety risk is increased; on the contrary, if H1 / T is large, that is, the first groove is deep, the first groove is easy to break, and the opening pressure will be too small.

[0017] In a possible implementation, the diameter D of the first groove is equal to the length L of the second groove. The second groove is set to pass through the center of the first groove, so that the second groove divides the first groove into two symmetrical parts, which is easy to process, and the second groove can be located in the middle area of ​​the cylindrical lithium battery, so that the explosion-proof disk can be opened smoothly to release pressure.

[0018] A second aspect of the embodiment of the present application provides a cap assembly, comprising the explosion-proof disk in the first aspect.

[0019] The cap assembly according to the second aspect of the embodiment of the present application has at least the following beneficial effects:

[0020] By using the explosion-proof plate in the first aspect, the cap assembly can improve the safety of the battery.

[0021] A third aspect of the embodiments of the present application provides a cylindrical lithium battery, comprising the cap assembly in the second aspect or the explosion-proof plate in the first aspect.

[0022] The cylindrical lithium battery according to the third aspect of the embodiment of the present application has at least the following beneficial effects:

[0023] As the cylindrical lithium battery is provided with the cap assembly in the second aspect or the explosion-proof plate in the first aspect, the cylindrical lithium battery has the characteristic of high safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 is a schematic top view of an explosion-proof disk provided in an embodiment of the present application;

[0026] Figure 2 yes Figure 1 A schematic diagram of the middle explosion-proof disk from a bottom view;

[0027] Figure 3 yes Figure 1 A schematic cross-sectional view of a middle explosion-proof disk in one direction;

[0028] Figure 4 yes Figure 3 The local schematic diagram of the A in the middle;

[0029] Figure 5 yes Figure 3 A partial schematic diagram of point B in the middle.

[0030] Reference numerals:

[0031] 10- Explosion-proof disk;

[0032] 100-explosion-proof plate body, 101-groove combination, 102-first groove, 103-second groove, 104-top surface, 105-bottom surface, 106-thinning portion, 107-flat surface, 108-rounded corners, 109-welding boss, 110-groove. DETAILED DESCRIPTION

[0033] Embodiments of the present embodiment are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present embodiment, and should not be construed as limiting the present embodiment.

[0034] In the description of this embodiment, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this embodiment.

[0035] In the description of this embodiment, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0036] In the description of this embodiment, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this embodiment based on the specific content of the technical solution.

[0037] The following combination Figures 1 to 4 The explosion-proof disk 10 provided in the embodiment of the present application is described in detail.

[0038] It should be noted that the explosion-proof plate 10 provided in the embodiment of the present application is used for cylindrical lithium batteries, such as 21 series batteries (cylindrical batteries with an outer diameter of 21 mm). Figure 1 is a schematic top view of the explosion-proof disk 10 provided in the embodiment of the present application, Figure 2 yes Figure 1 A bottom view of the middle explosion-proof disk 10, Figure 3 yes Figure 1 A cross-sectional view of the explosion-proof disk 10 in one direction, see Figures 1 to 3 The explosion-proof disc 10 comprises an explosion-proof disc body 100, which is usually a single component made of aluminum. It is understandable that in order to match the shape of a cylindrical lithium battery and minimize the occupation of the battery height direction, the explosion-proof disc body 100 is a circular thin disc or thin plate structure as a whole.

[0039] It can be understood that, for the explosion-proof disk body 100, along the thickness direction, it has two sides that are separated from each other, wherein, after being assembled into a cylindrical lithium battery, its bottom surface 105 ( Figure 3 The top surface 104 ( Figure 3 The upper middle part) is connected to the external space.

[0040] It should also be noted that when the cap assembly is assembled, the bursting disc body 100 needs to be connected and assembled with other components constituting the cap assembly, so there are structures such as bosses on both sides of the bursting disc body 100, and the bursting disc body 100 needs to be designed to have a certain thickness to meet the strength requirements. Since these structures are irrelevant to the purpose of this application, they are not introduced in this application.

[0041] Continue to refer Figure 1 and Figure 3 The explosion-proof disc body 100 is provided with a groove assembly 101 on one side of the top surface 104. The groove assembly 101 includes a first annular groove 102 and a second groove 103 extending in a straight line. The second groove 103 is located in the area defined by the first groove 102, and both ends of the second groove 103 are connected to the first groove 102. When the internal pressure of the cylindrical lithium battery exceeds a preset value, at least one of the first groove 102 and the second groove 103 breaks, thereby opening the explosion-proof disc 10. Moreover, the first groove 102 and the second groove 103 that breaks first can drive the other to break as well.

[0042] It can be understood that, since the explosion-proof disc 10 of the embodiment of the present application is provided with the annular first groove 102 and the linear second groove 103 on the explosion-proof disc body 100, and the two ends of the second groove 103 are connected to the first groove 102, therefore, when the internal pressure of the battery rises sharply due to abnormal conditions such as overheating and short circuit, when the pressure value of the edge area reaches the preset value first, the first groove 102 will break first, and the gas inside the battery will rush out from the gap caused by the break of the first groove 102 to release the pressure in time, and the first groove 102 will also drive the second groove 103 to break during the break process. When the gas pressure in the middle area reaches the preset value first, the second notch 103 will be broken first, and the gas inside the battery will rush out from the gap caused by the second notch 103 to release the pressure in time. In addition, the second notch 103 will also drive the first notch 102 to be broken during the process of breaking and opening, thereby expanding the opening area of ​​the explosion-proof plate 10 and improving the pressure relief effect. Therefore, when the gas pressure inside the battery exceeds the preset value, the explosion-proof plate 10 can be opened quickly and effectively to release the pressure, thereby improving the safety of the battery.

[0043] It should be noted that if the first groove 102 and the second groove 103 are not connected, they may only break separately and form a gap for pressure relief, but the pressure relief effect is not good, and the purpose of quickly and effectively relieving the pressure of the battery proposed in this application cannot be achieved. Therefore, in the embodiments of this application, the first groove 102 and the second groove 103 that make up the groove combination 101 are set to be connected, that is, they intersect. Therefore, after any one of them breaks, it can extend to the other, causing the other to also break. Therefore, the opening area of the explosion-proof sheet 10 can be enlarged, so as to quickly relieve the pressure of the battery.

[0044] It can be understood that the shape of the groove combination 101 composed of the first groove 102 and the second groove 103 as a whole is similar to the shape formed by two letters D back to back. Here, it is approximately equivalent to the shape of the Chinese character 'Ri' (日). Thus, 2 D-shaped blasting surfaces and 1 O-shaped blasting surface are formed on the explosion-proof sheet body 100.

[0045] It can be understood that although more complex internal grooves such as cross-shaped grooves can be used to replace the second groove 103 to achieve the purpose of timely blasting when the pressure in the middle area of the battery increases, this will significantly increase the processing difficulty of the explosion-proof sheet, resulting in a reduction in the yield rate and an increase in cost. In the embodiments of this application, only a straight second groove 103 is provided inside the explosion-proof sheet, which can effectively achieve quick and effective pressure relief of the battery while being easy to process and having a low cost, with better economic benefits.

[0046] It can be understood that the first groove 102 and the second groove 103 are structures formed on the explosion-proof sheet body 100 by removing materials. Therefore, the explosion-proof sheet body 100 is thinner at the positions where the first groove 102 and the second groove 103 are located than at the other positions. When the internal pressure of the battery increases and exceeds the preset value, according to the specific pressure position distribution, one or both of the first groove 102 and the second groove 103 will deform. When the deformation accumulates to a certain extent, the first groove 102 and the second groove 103 will break, and the broken materials will be turned over by the pressure to generate a gap at the break, and the high-pressure gas inside the battery will be released through the gap.

[0047] It can be understood that the opening pressure of the explosion-proof sheet, that is, the preset value, can be set according to actual needs. For example, by designing the specific cross-sectional shape and size of the first groove 102 and the second groove 103, the preset value can be adjusted. For example, the opening pressure of the explosion-proof sheet can be set to 0.8 - 1.5 Mpa.

[0048] It should be noted that Figure 3Although the groove assembly 101 is located on the top surface 104 side of the explosion-proof plate body 100 as an example for description, it is not limited to this. The groove assembly 101 can also be arranged on the bottom surface 105 of the explosion-proof plate body 100, that is, on the side facing the inside of the cylindrical lithium battery.

[0049] In some embodiments, Figure 1 As shown, the first groove 102 is in the shape of a ring, and the second groove 103 is set to pass through the center of the first groove 102, that is, the second groove 103 is just the diameter of the first groove 102. In this way, assuming that the diameter of the first groove 102 is D and the length of the second groove 103 is L, then L=D is satisfied. Therefore, the second groove 103 divides the first groove 102 into two symmetrical parts, which is convenient for processing and constructing the first groove 102 and the second groove 103, and after the explosion-proof plate is assembled to the cylindrical lithium battery, the second groove 103 is located in the middle area of ​​the cylindrical lithium battery, so that the explosion-proof plate 10 can be smoothly opened to release pressure. Further, it can be understood that in order to facilitate the construction of the first annular groove 102 and the linear second groove 103, the first groove 102 can be set to be co-centered with the explosion-proof plate body 100. Of course, it is not limited to this. For example, according to the specific pressure distribution inside the battery, the second groove 103 can be configured to divide the first groove 102 into two asymmetric parts and assemble them at a specific angle to meet actual usage requirements.

[0050] Furthermore, the size of the circular area defined by the first groove 102 can be reasonably designed according to the size of the cylindrical lithium battery and the opening conditions. For example, taking the 21 series lithium battery as an example, the diameter of the first groove 102 can be set to 7mm≤D≤11mm, and thus the length L of the second groove 103 is also between 7mm and 11mm.

[0051] As mentioned above, the explosion-proof disc body 100 also needs to be designed to have a certain thickness to meet the strength requirements for connection and assembly. It is understandable that if the thickness of the explosion-proof disc body 100 is too large, it will be difficult to open the explosion-proof disc. Figures 2 to 4In some embodiments, the explosion-proof disc body 100 is provided with a thinning portion 106 extending in the radial direction, the first notch 102 is arranged within the radial range where the thinning portion 106 is located, the thickness of the thinning portion 106 is T, and the following conditions are satisfied: 0.2mm≤T≤0.6mm. The thinning portion 106 can be realized by providing a groove 110 on one side of the explosion-proof disc body 100. Furthermore, the thinning portion 106 is a torus with a certain width, and the width of the thinning portion 106 is W, and the following conditions are satisfied: 3mm≤W≤8mm. The thickness and width of the thinning portion 106 are reasonably designed, which can effectively make the notch combination 101 break when the opening condition is met to relieve the pressure of the battery, and also ensure that the explosion-proof disc body 100 has sufficient strength and rigidity, which is convenient for processing and assembly. At the same time, when the internal pressure of the battery is relatively large, the thinning portion 106 itself may also break at the bottom of the groove 110, thereby helping the battery to relieve pressure quickly. Of course, the present invention is not limited thereto. When the explosion-proof disk body 100 itself is relatively thin, for example, when the thickness of the explosion-proof disk body 100 is within the above range, the thinned portion 106 may be omitted.

[0052] refer to Figure 4 and Figure 5 , relative to the surface of the explosion-proof disk body 100, the first groove 102 has a depth H1, and the second groove 103 has a depth H2. It can be understood that if H1 and H2 are large, that is, the first groove 102 and the second groove 103 are deep, the first groove 102 and the second groove 103 are easy to break, and the opening pressure will be too small. If H1 and H2 are large, that is, the first groove 102 and the second groove 103 are shallow, the first groove 102 and the second groove 103 are not easy to break, and the opening pressure will be too large, and the gas inside the battery cannot be released in time, increasing the safety risk. Therefore, in some embodiments, the ratio of the depth H1 of the first groove 102 to the thickness of the thinned portion 106 is between 30% and 60%, that is, it satisfies: 30%≤H1 / T≤60%, and more preferably, 40%≤H1 / T≤55%. The specific values ​​of H1 and H2 can be determined according to the opening pressure and the thickness of the thinned portion 106 (or the explosion-proof disk body 100).

[0053] It is understandable that the first groove 102 and the second groove 103 are arranged in different areas on the explosion-proof disc body 100. Specifically, the first groove 102 is arranged in a ring shape around the center of the explosion-proof disc body 100 on the end surface of the explosion-proof disc body 100, while the second groove 103 is radially constructed on the end surface of the explosion-proof disc body through the center of the explosion-proof disc body 100. Due to the requirements of strength, installation, etc., the thickness of the explosion-proof valve body 100 in different areas along the radial direction is usually different. For example, the wall thickness of the inner part of the explosion-proof valve body 100 adjacent to the thinning portion 106 is thicker than the thinning portion 106, and the wall thickness changes in a step-like manner and forms a thicker welding boss 109 in the middle (for welding with the bottom orifice plate in the cap assembly). Therefore, in order to ensure that the first groove 102 and the second groove 103 located in different areas of the explosion-proof valve body 100 can meet the smooth opening when the pressure reaches the preset value, in some embodiments, the depth of the first groove 102 is different from the depth of the second groove 103.

[0054] Furthermore, in some embodiments, the depth of the first groove 102 is less than the depth of the second groove 103. By increasing the depth of the second groove 103, the effect of the increased thickness of the explosion-proof valve body 100 in the middle region on the second groove 103 can be reduced, so as to ensure that the explosion-proof valve 10 is opened smoothly at the second groove 103.

[0055] Furthermore, the depth of the second groove 103 is set to be deeper in the middle and shallower at both ends. By setting the depth of the second groove 103 to be deeper in the middle and shallower at both ends, the influence of the step-wise change in the thickness of the explosion-proof valve body 100 in the radial direction can be reduced, so as to ensure that the explosion-proof valve 10 is opened smoothly at the second groove 103.

[0056] Continue to refer Figure 1 and Figure 3 Further, in some embodiments, for the purpose of facilitating the processing of the groove assembly 101, a flat surface 107 is provided on the side of the explosion-proof disc body 100 that is away from the inside of the cylindrical lithium battery, and the groove assembly 101 is formed on the flat surface 107. At the same time, a groove 110 is provided on the side of the explosion-proof disc body 100 that faces the inside of the cylindrical lithium battery to form a thinning portion 106. In this way, the groove 110 and the welding boss 109 located at the bottom of the explosion-proof disc 10 are reasonably arranged, and at the same time, the groove assembly 101 is also easily processed and formed on the flat surface 107. Of course, it is not limited to this, and the explosion-proof disc body 100 can also be arched. In this case, the surface of the explosion-proof disc body 100 that is away from the inside of the cylindrical lithium battery can also be curved or conical.

[0057] It is understandable that the cross-section of the groove assembly 101 can be set to various suitable shapes according to actual needs. For the purpose of facilitating processing and ensuring smooth opening under a set opening pressure, reference is made to Figure 4and Figure 5 In some embodiments, the cross section of the groove assembly 101 is in an inverted trapezoid, a rectangle or a V shape, that is, the cross section of the first groove 102 and the second groove 103 is in an inverted trapezoid, a rectangle or a V shape. The inverted trapezoid, a rectangle or a V-shaped cross section is easy to process and has a low cost.

[0058] In some embodiments, the cross-sectional shapes of the first groove 102 and the second groove 103 are the same, thereby ensuring that the fracture morphologies of the first groove 102 and the second groove 103 are consistent and can be opened smoothly when the pressure reaches a preset value.

[0059] Further, in order to reduce stress concentration and reduce the risk of accidental fracture of the groove assembly 101, continue to refer to Figure 4 and Figure 5 The bottom sides of the inverted trapezoid, rectangle or V-shape are all chamfered. By providing the chamfered corners 108 at the bottom of the first notch 102 and the second notch 103, the stress concentration at the bottom of the first notch 102 and the second notch 103 can be reduced, and the risk of accidental opening of the bursting disc when the pressure value does not reach the preset value can be reduced.

[0060] Furthermore, the radius of the fillet 108 set at the bottom of the first groove 102 and the second groove 103 is the same. By setting the radius of the fillet 108 of the first groove 102 and the second groove 103 to be the same, the design and manufacturing costs can be reduced. For example, the radius of the fillet 108 at the bottom of the first groove 102 and the second groove 103 is R, which satisfies: 0.05mm≤R≤0.15mm, more preferably, 0.05mm≤R≤0.1mm. When the radius of the fillet 108 is within this range, firstly, the stress concentration at the bottom of the first groove 102 and the second groove 103 can be effectively reduced, and secondly, it is also easy to process through a mold, which can reduce costs.

[0061] The explosion-proof disc 10 provided in the embodiment of the present application is used as a component to be assembled with other components such as a sealing ring, a perforated plate, an insulating plate and a top cover to form a cap assembly. The cap assembly is used as a component to be assembled with a metal shell, a winding core electrode group, etc. to form a cylindrical lithium battery.

[0062] It can be understood that, due to the use of the explosion-proof disc 10 of the above embodiment, the cap assembly of this embodiment can quickly release the pressure of the cylindrical lithium battery, thereby improving the safety of the battery.

[0063] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present implementation. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0064] Although examples of the present embodiment have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present embodiment, and the scope of the present embodiment is defined by the claims and their equivalents.

Claims

1. An explosion-proof sheet for a cylindrical lithium battery, characterized in that: include: A bursting disk body (100), wherein at least one side of the bursting disk body (100) is provided with a groove assembly (101), wherein the groove assembly (101) comprises a first annular groove (102) and a second linear groove (103), wherein the second groove (103) is located within a region defined by the first groove (102), and both ends of the second groove (103) are connected to the first groove (102); At least one of the first notch (102) and the second notch (103) breaks when the internal pressure of the cylindrical lithium battery exceeds a preset value, thereby causing the explosion-proof disk to open, and the first notch (102) and the second notch (103) that breaks first can drive the other to break as well.

2. The explosion-proof disk according to claim 1, characterized in that: The depth H1 of the first groove (102) is smaller than the depth H2 of the second groove (103).

3. The explosion-proof disk according to claim 1, characterized in that: The depth of the middle portion of the second groove (103) is greater than the depths of the two ends.

4. The explosion-proof disk according to claim 1, characterized in that: The bottoms of the first groove (102) and the second groove (103) are provided with rounded corners (108).

5. The explosion-proof disk according to claim 4, characterized in that: The radius of the chamfered corners (108) arranged at the bottom of the first groove (102) and the second groove (103) is the same.

6. The explosion-proof disk according to claim 5, characterized in that: The rounded corner (108) is R, which satisfies: 0.05mm≤R≤0.15mm.

7. The explosion-proof disk according to claim 1, characterized in that: The explosion-proof disk body (100) is provided with a thinned portion (106) extending in a radial direction, the first notch (102) is arranged within a radial range where the thinned portion (106) is located, the thickness of the thinned portion (106) is T, the depth of the first notch (102) is H1, and the following condition is satisfied: 30%≤H1 / T≤60%.

8. The explosion-proof disk according to claim 1, characterized in that: The diameter D of the first groove (102) is equal to the length L of the second groove (103).

9. A cap assembly, characterized in that: The explosion-proof disk comprises the explosion-proof disk as claimed in any one of claims 1 to 8.

10. A cylindrical lithium battery, characterized in that: It comprises the cap assembly according to claim 9 or the bursting disk according to any one of claims 1 to 8.

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