Cap assembly and cylindrical battery

Abstract

The utility model relates to the technical field of cylindrical battery structures, and provides a cap assembly and a cylindrical battery, the cap assembly comprises an outer insulating ring, a top cover plate, an anti-explosion sheet and an inner rubber ring, the inner rubber ring abuts against one side, far away from the top cover plate, of the anti-explosion sheet; a limiting ring is fixedly arranged on the anti-explosion piece and abuts against the peripheral side of the inner rubber ring, and the included angle beta between the outer side of the limiting ring and the anti-explosion piece ranges from 95 degrees to 125 degrees. According to the utility model, the limiting ring is arranged on the explosion-proof sheet, and the inner wall of the limiting ring is used for limiting the inner rubber ring, so that the inner rubber ring can be prevented from shifting in the assembling and using processes, a corresponding limiting structure does not need to be arranged on the inner rubber ring, and the processing difficulty of the inner rubber ring and the battery can be reduced; by limiting the included angle between the limiting ring and the anti-explosion piece and the specification of the limiting ring, the limiting and fixing effect of the limiting ring on the inner rubber ring can be improved, the machining convenience of the limiting ring can be improved, and the weight and material cost of the limiting ring are reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to cylindrical battery structure technical field especially relates to a cap subassembly and cylindrical battery. BACKGROUND

[0002] The cap subassembly is an important part of the battery, which is usually composed of an outer insulating ring, a top cover plate, an explosion-proof sheet and an inner rubber ring, etc. By precise matching of the components in the cap subassembly, good insulation and explosion-proof performance can be provided for the battery to ensure its safety.

[0003] The inner insulating sheet is mainly fixed by welding between the explosion-proof sheet and the lower end plate to limit the inner insulating sheet, so the overall limiting effect of the inner insulating sheet is not ideal. The fixation and limiting are achieved by welding between two metal sheets, which is difficult to assemble and is difficult to achieve concentricity. If applied to a working condition with more vibration, the inner rubber ring may be displaced.

[0004] For example, some existing technologies directly connect the explosion-proof sheet to the top cover and remove the insulating ring in the existing cap, which can reduce the height of the cap, increase the internal space of the battery and save costs. However, in order to limit the isolation ring, a protruding structure is provided on the side of the explosion-proof sheet away from the top cover, and the isolation ring is fitted outside the protruding structure. However, this limiting design requires a limiting groove on the isolation ring to cooperate with the protruding structure, which makes the structure of the isolation ring more complex and increases the processing difficulty of the isolation ring and the battery. In addition, if applied to a working condition with frequent vibration, the inner rubber ring may be displaced, and the stability of the cap cannot be well guaranteed. SUMMARY

[0005] Therefore, the utility model provides a cap subassembly and cylindrical battery which can limit the existing various inner rubber rings and help to reduce the processing difficulty of the inner rubber ring and the battery.

[0006] The technical scheme of the utility model is implemented as follows: on the one hand, the utility model provides a cap subassembly comprising an outer insulating ring, a top cover plate, an explosion-proof sheet and an inner rubber ring, wherein,

[0007] The top cover plate and the explosion-proof sheet are both sealingly fixed in the outer insulating ring and electrically connected.

[0008] The inner rubber ring is abutted on the side of the explosion-proof sheet away from the top cover plate.

[0009] A limiting ring is fixedly arranged on the explosion-proof sheet, the limiting ring abuts the circumferential side of the inner rubber ring, and the included angle β between the outer side of the limiting ring and the explosion-proof sheet is 95°-125°.

[0010] Preferably, the outer diameter of the explosion-proof sheet is L0, the minimum distance from the center position of the cross section of the side wall of the limiting ring to the circumferential side of the explosion-proof sheet is L1, and 20% L0≥L1≥10% L0.

[0011] Preferably, the thickness of the explosion-proof sheet at the position outside the limiting ring is H0, the axial length of the limiting ring is H1, and 80% H1≥H0≥60% H1.

[0012] Further preferably, the length of the inner rubber ring along the axial direction of the limiting ring is H2, 72% H2≥H1≥52% H2, and H1=0.4-0.6 mm.

[0013] Preferably, a gas leakage hole is formed in the inner rubber ring, the minimum distance from the inner wall of the gas leakage hole to the circumferential side of the inner rubber ring is D1, the thickness of the middle position of the side wall of the limiting ring is D2, 35% D1≥D2≥25% D1, and D2=0.2-0.4 mm.

[0014] Preferably, the wall thickness of the limiting ring gradually decreases from the end close to the explosion-proof sheet to the end away from the explosion-proof sheet, the wall thickness of the end close to the explosion-proof sheet is M1, the wall thickness of the end away from the explosion-proof sheet is M2, and 86% M1≥M2≥66% M1.

[0015] Further preferably, the included angle δ between the inner side of the limiting ring and the explosion-proof sheet is 70-85°.

[0016] Preferably, the side of the top cover plate close to the explosion-proof sheet is provided with a buffer cavity, a convex edge is integrally formed on the explosion-proof sheet, the convex edge is located in the buffer cavity and abuts against the side wall thereof.

[0017] The convex edge is coaxially arranged with the limiting ring, and the outer diameter of the end of the convex edge close to the explosion-proof sheet is not greater than the inner diameter of the end of the limiting ring close to the explosion-proof sheet.

[0018] Further preferably, a deformation groove is formed on the side of the explosion-proof sheet away from the inner rubber ring, the deformation groove is coaxially arranged with the convex edge, and the outer diameter of the end of the deformation groove away from the inner rubber ring is not greater than the inner diameter of the end of the convex edge close to the explosion-proof sheet.

[0019] In a second aspect, the utility model provides a cylindrical battery comprising the cap assembly.

[0020] The cap assembly and the cylindrical battery have the following beneficial effects compared with the prior art:

[0021] (1) By setting the limiting ring on the explosion-proof sheet, the inner rubber ring is limited by the inner wall of the limiting ring, which can not only avoid displacement of the inner rubber ring during assembly and use, but also does not need to set the corresponding limiting structure on the inner rubber ring, thereby helping to reduce the processing difficulty of the inner rubber ring and the battery.

[0022] (2) By limiting the angle between the limiting ring and the explosion-proof sheet and the specification of the limiting ring, the limiting and fixing effect of the limiting ring on the inner rubber ring can be improved, the processing convenience of the limiting ring can be improved, and the weight and material cost of the limiting ring can be reduced.

[0023] (3) By setting the convex edge and limiting the outer diameter of the convex edge, the inner diameter of the limiting ring and the outer diameter of the deformation groove, the structural strength of the position where the explosion-proof sheet plays a supporting role can be ensured, thereby improving the structural stability of the cap assembly. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the drawings needed in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0025] Figure 1 is a sectional view of the cap assembly of the present application;

[0026] Figure 2 is Figure 1 is an enlarged view of A in the middle;

[0027] Figure 3 is a partial sectional view of the explosion-proof sheet in the cap assembly of the present application;

[0028] Figure 4 is a partial sectional view of the inner rubber ring in the cap assembly of the present application;

[0029] Figure 5 is a partial sectional view of the cylindrical battery of the present application.

[0030] Wherein: 1, outer insulating ring; 2, top cover plate; 201, buffer cavity; 3, explosion-proof sheet; 31, limiting ring; 32, convex edge; 301, deformation groove; 4, inner rubber ring; 401, air leakage hole. DETAILED DESCRIPTION

[0031] The technical solutions in the utility model will be clearly and completely described below in combination with the specific implementation manners of the utility model. Apparently, the described implementation manners are only a part of the implementation manners of the utility model, rather than all the implementation manners. Based on the implementation manners in the utility model, all the other implementation manners obtained by the ordinary skilled in the art without creative labor fall within the protection scope of the utility model.

[0032] Cylindrical batteries are divided into cylindrical primary batteries and cylindrical secondary batteries, which have been widely applied in the fields of electronic devices, industrial devices, energy storage and transportation tools, etc. due to the advantages of good consistency, high energy density and good heat dissipation performance, etc.

[0033] The cap assembly is an important component of the cylindrical battery, which is composed of multiple components. When the cap assembly is assembled and processed or the cylindrical battery is applied in an environment with more vibration, the components in the cap assembly are prone to eccentric displacement, which affects the overall performance of the cylindrical battery.

[0034] The cylindrical battery of the utility model comprises a shell, a cap assembly, a lower end plate, a battery cell and a current collector plate, wherein the cap assembly comprises an outer insulating ring 1, a top cover plate 2, an explosion-proof sheet 3 and an inner rubber ring 4. By improving the structure of the explosion-proof sheet 3, the inner rubber ring 4 can be limited, so that the inner rubber ring 4 will not be displaced during the assembly and processing of the cylindrical battery or when the cylindrical battery is applied in an environment with more vibration, thereby ensuring the overall performance of the cylindrical battery.

[0035] The positive electrode of the battery cell, the positive electrode current collector plate, the lower end plate, the explosion-proof sheet 3 and the top cover plate 2 are sequentially electrically connected. The top cover plate 2 and the explosion-proof sheet 3 are both sealingly fixed in the outer insulating ring 1. The inner wall of the outer insulating ring 1 holds the top cover plate 2 and the explosion-proof sheet 3 together. The outer insulating ring 1 is fixedly arranged at the opening position of the shell, so as to fix the top cover plate 2 and the explosion-proof sheet 3 at the opening of the shell and insulate the top cover plate 2 and the explosion-proof sheet 3 from the shell.

[0036] The top cover plate 2 is used for electrically connecting with external electrical equipment. It is located on the side of the explosion-proof sheet 3 away from the battery cell. The inner rubber ring 4 is abutted on the side of the explosion-proof sheet 3 away from the top cover plate 2. The lower end plate is fixedly arranged on the inner rubber ring 4. The lower end plate penetrates through the inner rubber ring 4 and is welded with the explosion-proof sheet 3. Figure 2As shown, the limiting ring 31 is fixedly arranged on the explosion-proof sheet 3, and the inner rubber ring 4 is arranged inside the limiting ring 31. The inner wall of the limiting ring 31 limits the side of the inner rubber ring 4, so that the inner rubber ring 4 cannot be displaced relative to the explosion-proof sheet 3. At the same time, the limiting design structure is simple, and no corresponding structure needs to be arranged on the inner rubber ring 4, which is beneficial to reduce the processing difficulty of the inner rubber ring 4 and other components. The limiting ring 31 can also limit the inner rubber ring 4 of different shapes, thereby improving the assembly efficiency of the cylindrical battery and the adaptability of the cap assembly to the inner rubber ring 4.

[0037] As shown in Figure 2 Preferably, the limiting ring 31 is arranged in a conical structure, and the inner diameter of the end of the limiting ring 31 close to the explosion-proof sheet 3 is greater than the inner diameter of the end of the limiting ring 31 away from the explosion-proof sheet 3. When the inner rubber ring 4 is arranged in the limiting ring 31, the conical inner wall of the limiting ring 31 abuts against the outer wall of the inner rubber ring 4, so that the inner rubber ring 4 is tightly attached to the explosion-proof sheet 3. This not only improves the abutting tightness of the inner rubber ring 4 and the explosion-proof sheet 3, but also limits the inner rubber ring 4 in the axial direction of the limiting ring 31, thereby improving the assembly efficiency of the cap assembly.

[0038] In order to adapt to the cylindrical shell of the cylindrical battery, the projections of the outer insulating ring 1, the top cover plate 2, the explosion-proof sheet 3 and the inner rubber ring 4 on the end face of the cylindrical battery are all circular, and the outer insulating ring 1, the top cover plate 2, the explosion-proof sheet 3, the limiting ring 31 and the inner rubber ring 4 are preferably coaxially arranged.

[0039] As shown in Figure 1 and Figure 3 The angle between the outer side of the limiting ring 31 and the explosion-proof sheet 3 is β, the outer diameter of the explosion-proof sheet 3 is L0, the center position of the cross section of the side wall of the limiting ring 31 is P, and the minimum distance from P to the side of the explosion-proof sheet 3 is L1.

[0040] In some embodiments, 125°≥β≥95°, that is, the angle between the outer side of the limiting ring 31 and the explosion-proof sheet 3 can be 95°, 100°, 105°, 110°, 115°, 120° or 125°, etc. The limiting ring 31 is mainly used for limiting and fixing the inner rubber ring 4. If β<95°, the inclination of the side wall of the limiting ring 31 is small, the fixing effect of the inner wall of the limiting ring 31 on the outer wall of the inner rubber ring 4 is reduced, and the inner rubber ring 4 is displaced along the axial direction of the limiting ring 31, which cannot effectively improve the assembly efficiency of the cap assembly. If β>125°, the inclination of the side wall of the limiting ring 31 is large, and when the inner rubber ring 4 is installed in the limiting ring 31, the end of the inner rubber ring 4 close to the explosion-proof sheet 3 is easy to have a gap with the limiting ring 31, which reduces the contact area between the inner rubber ring 4 and the limiting ring 31, and the problem of the limiting ring 31 crushing the side wall of the inner rubber ring 4 is easy to occur. At the same time, the limiting ring 31 is preferably integrally formed with the explosion-proof sheet 3, and if β>125°, the shaping processing of the limiting ring 31 is difficult, and the structural strength of the limiting ring 31 is low, which is easy to be separated from the explosion-proof sheet 3 when subjected to external force.

[0041] In some embodiments, 20%L0≥L1≥10%L0, that is, the minimum distance from the center position of the cross section of the side wall of the limiting ring 31 to the peripheral side of the explosion-proof sheet 3 can be 10%, 15% or 20% of the outer diameter of the explosion-proof sheet 3, etc. When the cap assembly is installed in the shell, the extrusion of the shell on the outer insulating ring 1 will cause it to shrink and deform. If L1<10%L0, the limiting ring 31 is too close to the outer insulating ring 1, which causes the outer insulating ring 1 to have insufficient shrinkage space, which reduces the sealing performance of the battery seal, and causes the battery to have problems such as poor sealing and liquid leakage. If L1>20%L0, the outer diameter of the inner rubber ring 4 and the lower end plate inside the limiting ring 31 is too small, which reduces the weldable area of the lower end plate and the positive current collector disc, reduces the overcurrent capacity of the welding part, and increases the heat generation of the welding part, which affects the performance of the cylindrical battery.

[0042] In some embodiments, L0=19.6mm, L1=2.9mm, that is, L1=15%L0.

[0043] The position of the explosion-proof sheet 3 outside the limiting ring 31 serves to connect and fix the outer insulating ring 1, and a plurality of gas leakage holes 401 are formed in the inner rubber ring 4. When the battery is in thermal runaway, the gas inside the battery will pass through the lower end plate and the gas leakage hole 401 to break through the position of the explosion-proof sheet 3 inside the limiting ring 31. Therefore, the thickness of the position of the explosion-proof sheet 3 inside the limiting ring 31 should be smaller than the thickness of the position of the explosion-proof sheet 3 outside the limiting ring 31.

[0044] As Figure 3 and Figure 4As shown, the thickness of the explosion-proof sheet 3 at the position outside the limiting ring 31 is H0, the axial length of the limiting ring 31 is H1, and the length of the inner rubber ring 4 along the axial direction of the limiting ring 31 is H2.

[0045] In some embodiments, 80% H1≥H0≥60% H1, that is, the thickness of the explosion-proof sheet 3 at the position outside the limiting ring 31 can be 60%, 65%, 70%, 75%, or 80% of the axial length of the limiting ring 31, etc. If H0<60% H1, the position of the explosion-proof sheet 3 that plays a supporting and fixing role is relatively weak, and when receiving external force, the explosion-proof sheet 3 is prone to deformation, thereby causing the valve to open prematurely, resulting in the scrapping of the battery; if H0>80% H1, the explosion-proof sheet 3 is relatively thick, which increases the cost and weight of the cap assembly, reduces the energy density of the battery, and increases the manufacturing cost of the battery.

[0046] In some embodiments, 72% H2≥H1≥52% H2, that is, the axial length of the limiting ring 31 can be 52%, 65%, or 72% of the length of the inner rubber ring 4 along the axial direction of the limiting ring 31, etc. If H1<52% H2, the difference between the inner wall height of the limiting ring 31 and the outer wall of the inner rubber ring 4 is large, resulting in a small contact area between the limiting ring 31 and the inner rubber ring 4, thereby making the inner rubber ring 4 prone to shaking and displacement, reducing the limiting and fixing effect of the limiting ring 31; if H1>72% H2, the length of the limiting ring 31 is large, which not only increases the processing difficulty of the limiting ring 31, but also increases the cost and weight of the cap assembly, reduces the energy density of the battery, and increases the manufacturing cost of the battery.

[0047] In some embodiments, H1=0.4-0.6mm, preferably H1=0.5mm, and H0=70% H1.

[0048] As shown in Figure 2 In order to ensure the connection strength of the limiting ring 31 and the explosion-proof sheet 3, reduce the processing cost of the limiting ring 31, and increase the energy density of the battery, it is preferred that the wall thickness of the limiting ring 31 gradually decreases from the end of the limiting ring 31 close to the explosion-proof sheet 3 to the end of the limiting ring 31 away from the explosion-proof sheet 3.

[0049] As shown in Figure 3 and Figure 4 The minimum distance from the inner wall of the air leakage hole 401 to the outer side of the inner rubber ring 4 is D1, the wall thickness of the limiting ring 31 at P is D2, the wall thickness of the limiting ring 31 at the end close to the explosion-proof sheet 3 is M1, the wall thickness of the limiting ring 31 at the end away from the explosion-proof sheet 3 is M2, and the included angle δ between the inner side of the limiting ring 31 and the explosion-proof sheet 3.

[0050] In some embodiments, 35% D1≥D2≥25% D1, i.e. the thickness of the middle position of the side wall of the limiting ring 31 can be 25%, 30% or 35% of the minimum distance from the inner wall of the air leakage hole 401 to the side of the inner rubber ring 4, etc. If D2<25% D1, the structural strength of the limiting ring 31 is poor, and the limiting and fixing ability of the inner rubber ring 4 is also relatively low, which causes the limiting ring 31 to be unable to effectively fix the inner rubber ring 4 and the lower end plate, especially when the battery is applied in a working condition with frequent vibration, the lower end plate will produce a large swing, thereby tearing the welding point of the lower end plate and the explosion-proof sheet 3, causing the battery to be scrapped; if D2>35% D1, the wall thickness of the limiting ring 31 is large, which will increase the cost and weight of the cap assembly, reduce the energy density of the battery, and increase the manufacturing cost of the battery.

[0051] In some embodiments, D2=0.2-0.4 mm, preferably D2=0.3 mm, and D1=1.07 mm, i.e. D2=28% D1.

[0052] In some embodiments, 86% M1≥M2≥66% M1, i.e. the wall thickness of the end of the limiting ring 31 away from the explosion-proof sheet 3 can be 66%, 76% or 86% of the wall thickness of the end of the limiting ring 31 close to the explosion-proof sheet 3, etc. If M2<66% M1, the structural strength of the limiting ring 31 is low, and the limiting and fixing ability of the inner rubber ring 4 is weak, which is prone to cause the problem of displacement of the inner rubber ring 4; if M2>86% M1, the process of the limiting ring 31 is difficult to implement, which is prone to produce defective products, at the same time, it will also increase the cost and weight of the cap assembly, reduce the energy density of the battery, and increase the manufacturing cost of the battery.

[0053] In some embodiments, M1=0.24-0.44 mm, preferably M1=0.34 mm, and M2=0.26 mm, i.e. M2=76% M1.

[0054] In some embodiments, 85°≥δ≥70° and 125°≥β≥95°, i.e. the angle between the outer side of the limiting ring 31 and the explosion-proof sheet 3 is kept at the above angle, and the angle between the inner side of the limiting ring 31 and the explosion-proof sheet 3 can be 70°, 75°, 80° or 85°, etc. If δ<70°, the processing of the limiting ring 31 is difficult to implement, and the subsequent shaping is also relatively difficult, and the limiting and fixing effect of the limiting ring 31 on the inner rubber ring 4 is reduced; if δ>85°, the resisting effect of the inner wall of the limiting ring 31 on the inner rubber ring 4 is relatively poor, which causes the inner rubber ring 4 to easily separate from the limiting ring 31, affecting the stability of the cap assembly.

[0055] In some embodiments, δ=80°.

[0056] As Figure 1As shown, the side of the top cover plate 2 close to the explosion-proof sheet 3 is provided with a buffer cavity 201, and the gas generated when the battery is out of control can enter the buffer cavity 201 to buffer, so as to reduce the risk of explosion of the battery.

[0057] In order to improve the concentric effect of the explosion-proof sheet 3 and the top cover plate 2, a convex edge 32 is integrally formed on the explosion-proof sheet 3, the convex edge 32 is located in the buffer cavity 201 and abuts against the side wall, and in the assembly process of the cap assembly, the limiting cooperation of the convex edge 32 with the inner wall of the buffer cavity 201 can quickly position the explosion-proof sheet 3 and the top cover plate 2, thereby reducing the assembly difficulty of the cap assembly and improving the assembly efficiency of the cap assembly.

[0058] As shown in the drawings, Figure 2 As shown, the side of the explosion-proof sheet 3 away from the inner rubber ring 4 is provided with a deformation groove 301, when the middle position of the lower side of the explosion-proof sheet 3 is impacted by the gas, the explosion-proof sheet 3 is more easily broken, so as to improve the sensitivity of the protection performance of the explosion-proof sheet 3.

[0059] In order to improve the uniformity of the explosion-proof sheet 3, the convex edge 32, the deformation groove 301 and the limiting ring 31 are coaxially arranged, as shown in the drawings, Figure 2 The outer diameter of the end of the convex edge 32 close to the explosion-proof sheet 3 is not greater than the inner diameter of the end of the limiting ring 31 close to the explosion-proof sheet 3, and the outer diameter of the end of the deformation groove 301 away from the inner rubber ring 4 is not greater than the inner diameter of the end of the convex edge 32 close to the explosion-proof sheet 3, so that the positions of the limiting ring 31, the convex edge 32 and the deformation groove 301 on the explosion-proof sheet 3 are staggered and do not overlap each other, which is not only beneficial to maintaining the performance of the explosion-proof sheet 3, but also avoids mutual influence between the limiting ring 31, the convex edge 32 and the deformation groove 301.

[0060] The working principle of the cap assembly and the cylindrical battery of the utility model is as follows:

[0061] As shown in the drawings, Figure 1 And Figure 2 As shown in the drawings, in the assembly of the top cover plate 2, the explosion-proof sheet 3 and the inner rubber ring 4, the abutting cooperation of the convex edge 32 and the buffer cavity 201 can quickly position the top cover plate 2 and the explosion-proof sheet 3, so that they are coaxially arranged, and the abutting cooperation of the limiting ring 31 and the inner rubber ring 4 can not only quickly position the inner rubber ring 4 and the explosion-proof sheet 3, so that they are coaxially arranged, but also can abut and fix the inner rubber ring 4 on the explosion-proof sheet 3, thereby reducing the assembly difficulty of the cap assembly and the battery and improving the assembly efficiency of the cap assembly and the battery.

[0062] The above is only a preferred embodiment of the utility model, and is not used to limit the utility model, any modification, equivalent replacement, improvement, etc. within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A cap assembly comprising an outer insulating ring (1), a top cover plate (2), a rupture disc (3) and an inner rubber ring (4), wherein, the top cover plate (2) and the rupture disc (3) are both sealingly fixed in the outer insulating ring (1) and electrically connected; the inner rubber ring (4) is abutting against one side of the rupture disc (3) away from the top cover plate (2); characterized in that a limiting ring (31) is fixedly arranged on the rupture disc (3), the limiting ring (31) abuts against the circumferential side of the inner rubber ring (4), and the angle β between the outer side of the limiting ring (31) and the rupture disc (3) is 95°-125°.

2. A cap assembly as defined in claim 1, wherein: The outer diameter of the rupture disc (3) is L0, and the minimum distance from the center position of the cross section of the side wall of the limiting ring (31) to the circumferential side of the rupture disc (3) is L1, wherein 20% L0≥L1≥10% L0.

3. A cap assembly as defined in claim 1, wherein: The thickness of the rupture disc (3) at the position outside the limiting ring (31) is H0, and the axial length of the limiting ring (31) is H1, wherein 80% H1≥H0≥60% H1.

4. A cap assembly as claimed in claim 3, wherein: The length of the circumferential side of the inner rubber ring (4) in the axial direction of the limiting ring (31) is H2, wherein 72% H2≥H1≥52% H2, and H1=0.4-0.6 mm.

5. A cap assembly as claimed in any one of claims 1 to 4 wherein: A gas leakage hole (401) is arranged in the inner rubber ring (4), the minimum distance from the inner wall of the gas leakage hole (401) to the circumferential side of the inner rubber ring (4) is D1, and the thickness of the middle position of the side wall of the limiting ring (31) is D2, wherein 35% D1≥D2≥25% D1, and D2=0.2-0.4 mm.

6. A cap assembly as claimed in any one of claims 1 to 4 wherein: The wall thickness of the limiting ring (31) gradually decreases from the end close to the rupture disc (3) to the end away from the rupture disc (3), the wall thickness of the end close to the rupture disc (3) of the limiting ring (31) is M1, and the wall thickness of the end away from the rupture disc (3) of the limiting ring (31) is M2, wherein 86% M1≥M2≥66% M1.

7. A cap assembly as claimed in claim 6, wherein: The angle δ between the inner side of the limiting ring (31) and the rupture disc (3) is 70°-85°.

8. A cap assembly as claimed in any one of claims 1 to 4 wherein: The side of the top cover plate (2) close to the rupture disc (3) is provided with a buffer cavity (201), the rupture disc (3) is integrally formed with a convex edge (32), the convex edge (32) is located in the buffer cavity (201) and abuts against the side wall thereof; The convex edge (32) is coaxially arranged with the limiting ring (31), and the outer diameter of the end of the convex edge (32) close to the rupture disc (3) is not greater than the inner diameter of the end of the limiting ring (31) close to the rupture disc (3).

9. A cap assembly as claimed in claim 8, wherein: The side of the rupture disc (3) away from the inner rubber ring (4) is provided with a deformation groove (301), the deformation groove (301) is coaxially arranged with the convex edge (32), and the outer diameter of the end of the deformation groove (301) away from the inner rubber ring (4) is not greater than the inner diameter of the end of the convex edge (32) close to the rupture disc (3).

10. A cylindrical battery characterized by: The cap assembly according to any one of claims 1-9.

Images