Cap assembly and cylindrical battery

Abstract

The utility model relates to the technical field of battery energy storage, in particular to a cap assembly and a cylindrical battery, the cap assembly comprises an outer insulating ring, an anti-explosion sheet and a top cover plate, the outer insulating ring comprises a first part and a second part which are arranged perpendicular to each other; the anti-explosion sheet is arranged on the second part and is perpendicular to the first part; the top cover plate is stacked on the top of the anti-explosion piece and is perpendicular to the first part. The tail end of the anti-explosion piece is flush with the tail end of the top cover plate and abuts against the first part. The first part is provided with a limiting structure which is used for limiting and fixing the explosion-proof sheet and the top cover plate on the outer insulating ring. According to the utility model, a full-package or half-package structural form is canceled, so that the overall weight of the cap can be reduced, the energy density of the battery is increased, the full-package or half-package structural form is canceled, a procedure of wrapping the top cover plate by the flanging of the explosion-proof sheet is omitted, and the explosion-proof sheet is easier to manufacture and implement in the production process; the production efficiency is greatly improved, and the production cost of the cap is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of battery energy storage, and particularly relates to a cap assembly and a cylindrical battery. BACKGROUND

[0002] In the field of battery energy storage today, cylindrical batteries are widely used in various electronic devices, electric vehicles and energy storage systems due to their unique advantages. Among them, the cap assembly of the cylindrical battery as a key component plays a crucial role in the performance, safety and production efficiency of the battery.

[0003] The common 21 series cylindrical small battery cap on the market mainly adopts a half-wrapped or fully-wrapped structure, such as the technical solution disclosed in the invention patent CN119275449A. This patent aims to solve some problems of the battery cap in structure and performance, however, the edge wrapping structure adopted still has many limitations in actual production and application. In the production process, when adopting a fully-wrapped or half-wrapped structure, the explosion-proof sheet needs to be reserved a certain length for wrapping the flange of the top cover plate, which undoubtedly increases the weight of the battery cap. With the increase of the weight of the cap, the energy density of the battery as a whole decreases accordingly, which is a problem that needs to be solved for modern battery technology that pursues high energy density. Because the reduction of energy density means that the amount of electricity that the battery can store decreases under the same volume or weight, which directly affects the endurance and use effect of the battery.

[0004] In addition, this structure is relatively complicated in manufacturing process. In addition to the conventional welding process, a process of wrapping the flange of the top cover plate with the explosion-proof sheet is also needed. One more process not only increases the production time and labor cost, but also may introduce more quality risk points. In actual production, each additional process means that the production efficiency will be reduced, and the production cost will also rise. This will undoubtedly have a negative impact on the market competitiveness of the product for battery enterprises with large-scale production.

[0005] In terms of performance and safety of the battery, the fully-wrapped or half-wrapped structure also has potential problems. Due to the complex structure, in the process of charging and discharging of the battery, the normal working performance of the explosion-proof sheet may be affected by the interaction between the components. For example, when the internal pressure of the battery abnormally rises, the opening pressure of the explosion-proof sheet may be disturbed by structural factors, causing the pressure to be released in time and effectively, thereby increasing the risk of safety accidents of the battery.

[0006] In summary, the existing cylindrical battery cap based on full or half package structure has defects in weight control, production efficiency, cost control, and battery performance and safety. In this context, it has important practical significance to develop a new type of cap assembly and cylindrical battery, which can effectively solve the above problems and promote the further development of battery energy storage technology. Utility model content

[0007] To avoid the occurrence of the above-mentioned adverse failures, the utility model provides a cap assembly and cylindrical battery. The cap newly designed by the utility model can solve the current technical problems, cancel the full or half package structure, so that the overall weight of the cap can be reduced, the energy density of the battery is increased, and the full or half package structure is canceled, so that a process of wrapping the top cover plate with the explosion-proof sheet flange is saved, which is easier to manufacture and realize in the production process, greatly improves the production efficiency, and reduces the production cost of the cap.

[0008] To solve the above technical problems, the utility model realizes the following technical scheme:

[0009] In the first aspect, the utility model provides a cap assembly, which is characterized by comprising

[0010] The outer insulating ring comprises a first part and a second part arranged perpendicular to each other.

[0011] The explosion-proof sheet is arranged on the second part and perpendicular to the first part.

[0012] The top cover plate is stacked on the top of the explosion-proof sheet and perpendicular to the first part.

[0013] The end of the explosion-proof sheet is flush with the end of the top cover plate, and both ends abut against the first part.

[0014] The first part is provided with a limiting structure for limiting and fixing the explosion-proof sheet and the top cover plate on the outer insulating ring.

[0015] As a further optimization scheme of the utility model, the relationship between the sum H2 of the height of the explosion-proof sheet and the height H0 of the outer insulating ring is: H2 / H0=18%-28%.

[0016] As a further optimization scheme of the utility model, the relationship between the height H3 of the second part and the height H0 of the outer insulating ring is: H3 / H0=20%-32%.

[0017] As a further optimization scheme of the utility model, the relationship between the vertical height H1 between the top surface of the first part and the top surface of the top cover plate and the height H0 of the outer insulating ring is: H1 / H0=45%-60%.

[0018] As a further optimization scheme of the utility model, the horizontal width W1 between the end of the top cover plate and the first part outer wall and the sum W0 of the horizontal width of the limiting structure and the first part is related as: W1 / W0=68%-80%.

[0019] As a further optimization scheme of the utility model, the height H21 of the top cover plate and the height H22 of the anti-explosion sheet are related as: H21 / H22=95%-125%.

[0020] As a further optimization scheme of the utility model, the second part top close to the anti-explosion sheet is provided with a groove for storing glue solution.

[0021] As a further optimization scheme of the utility model, the longitudinal section area S10 of the groove is 0.04-0.1mm 2 .

[0022] As a further optimization scheme of the utility model, the limiting structure is a protrusion formed by the first part inner wall bulging radially inward of the outer insulation ring.

[0023] In the second aspect, the utility model provides a cylindrical battery comprising the cap assembly in the above technical scheme.

[0024] The utility model discloses an innovative design of cap assembly structure and the optimization of the size relationship of each component, which has significant advantages in reducing weight, improving production efficiency, enhancing battery performance and safety, etc., and brings a new development idea for the field of cylindrical batteries. Its beneficial effects mainly reflect in the following aspects:

[0025] (1) cancel the full package or half package structure form, reduce the reserved length of the anti-explosion sheet for wrapping the top cover plate flange, thereby reducing the overall weight of the cap. In the case of reducing the overall weight of the battery, the energy density of the battery is improved, the energy storage efficiency of the battery is improved, the battery can store more power under the same volume or weight, and the competitiveness of the battery in the market is enhanced.

[0026] (2) the traditional full package or half package structure needs to increase the wrapping flange process to carry out welding, and the utility model cancels the structure form, reduces the process of wrapping the flange of the anti-explosion sheet on the top cover plate. This makes the production process more simple and direct, reduces the production link, reduces the production complexity, and thus improves the production efficiency, saves the production time and labor cost.

[0027] (3) The protrusions formed by the first part outer wall along the radial inner side of the outer insulation ring as a limiting structure, which not only fixes the position of the explosion-proof sheet and the top cover plate, but also enhances the structural strength of the outer insulation ring. By reasonably designing the ratio of the horizontal width W1 between the end of the top cover plate and the first part outer wall and the sum W0 of the horizontal width of the limiting structure and the first part (W1 / W0 = 68%-80%), the difficulty of assembling the explosion-proof sheet and the top cover plate into the outer insulation ring is moderate, avoiding the problems of difficult assembly and low production efficiency due to W0 being too large, or insufficient strength of the outer insulation ring, unstable assembly, and reduced air tightness due to W0 being too small, ensuring the stability and reliability of the cap assembly.

[0028] (4) The ratio of the sum H2 of the height of the explosion-proof sheet and the top cover plate and the height H0 of the outer insulation ring (H2 / H0 = 18%-28%) is controlled, avoiding the problems of the top cover plate and the explosion-proof sheet being too thin, the strength being poor, the stability of the explosion-proof valve opening pressure being affected, and the outer insulation ring being too short, the battery air tightness being poor, and liquid leakage, ensuring the safety performance of the battery. The relationship between the second part height H3 and the outer insulation ring height H0 (H3 / H0 = 20%-32%) is optimized, preventing the problems of poor battery air tightness, unstable sealing pressure, and increased liquid leakage probability due to insufficient thickness of the outer insulation ring when the groove is sealed, and the battery internal effective capacity being small and the battery capacity being reduced due to H3 being too large, ensuring the performance and safety of the battery. The ratio of the vertical height H1 between the top surface of the first part and the top surface of the top cover plate and the height H0 of the outer insulation ring is set to 45%-60%, avoiding the problems of insufficient sealing flange of the outer insulation ring, poor battery air tightness due to H1 being too small, and interference between the flange of the outer insulation ring and the top cover plate, poor sealing, and battery liquid leakage due to H1 being too large, ensuring the safety performance of the battery.

[0029] (5) The ratio of the height H21 of the top cover plate and the height H22 of the explosion-proof sheet (H21 / H22 = 95%-125%) is reasonably designed, avoiding the problems of low strength of the top cover plate, explosion point and virtual welding during welding due to H21 being too small, and increased difficulty of stretching the top cover plate and rising manufacturing costs due to H21 being too large, as well as the strength of the explosion-proof sheet being reduced and the opening pressure being unstable due to H22 being too small, improving the welding quality and the structural stability of the cap assembly, and ensuring the safety performance of the battery.

[0030] (6) A groove for storing glue is provided on the top of the second part adjacent to the explosion-proof sheet, and the longitudinal cross-sectional area S10 of the groove is 0.04-0.1mm 2 . Such design enables the glue to be squeezed and coated onto the contact surface of the explosion-proof sheet and the outer insulation ring after the cap is sealed into the shell, and the excess glue is still stored in the groove, avoiding the glue overflowing into the battery and affecting the battery performance, and ensuring the stability of the battery performance. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is the cross section structure schematic view of the cap assembly of the embodiment of the utility model.

[0032] Figure 2 It is the cross section structure schematic view of the cap assembly of the embodiment of the utility model. Figure 1

[0033] Figure 3 It is the cross section structure schematic view of the cap assembly of the embodiment of the utility model. Figure 2

[0034] Figure 4 It is the cross section structure schematic view of the cap assembly of the embodiment of the utility model.

[0035] Reference signs: 1-outer insulation ring, 11-first part, 12-second part, 13-groove, 14-extension section, 2-explosion-proof sheet, 21-upper boss, 22-lower boss, 23-lower boss, 24-outer circumferential groove, 25-central groove, 3-top cover plate, 4-inner rubber ring, 5-lower end plate. DETAILED DESCRIPTION

[0036] In order to make the technical personnel in the art better understand the technical scheme of the utility model, the preferred implementation scheme of the utility model is described below in combination with specific embodiments, but it should be understood that the drawings are only used for exemplary description, and cannot be understood as the limitation of the patent; in order to better illustrate the embodiments, some components in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures in the drawings and their descriptions may be omitted. The positional relationship described in the drawings is only used for exemplary description, and cannot be understood as the limitation of the patent.

[0037] As shown in Figures 1-3 The utility model discloses an embodiment provides a cap assembly, including outer insulation ring 1, explosion -proof sheet 2 and top cover plate 3. Wherein, outer insulation ring 1 includes the first part 11 and the second part 12 that set up mutually perpendicularly, and explosion -proof sheet 2 sets up on the second part 12, and it is perpendicular to the first part 11, and top cover plate 3 is stacked on the top of explosion -proof sheet 2, and it is perpendicular to the first part 11, and the end of explosion -proof sheet 2 is flush with the end of top cover plate 3, and the end is all with the first part 11 and reaches, and the first part 11 is provided with the limiting structure for limiting and fixing explosion -proof sheet 2 and top cover plate 3 on outer insulation ring 1.

[0038] ​​From the above structural design, the newly designed cap cancels the full or half package structure, which can reduce the overall weight of the cap, increase the energy density of the battery, and cancel the full and half package structure, which reduces the process of turning over the top cover plate 3 wrapped by the explosion-proof sheet 2. In the production process, it is easier to make and realize, the production efficiency is greatly improved, and the production cost of the cap is reduced.

[0039] In some examples, the first part 11 and the second part 12 of the outer insulation ring 1 are integrally formed and are both made of plastic material.

[0040] In some examples, the limiting structure is a protrusion formed by the inner wall of the first part 11 protruding radially inward of the outer insulation ring 1. The protrusion mainly functions as a fixing and reinforcing rib, fixing the positions of the explosion-proof sheet 2 and the top cover plate 3, ensuring that the explosion-proof sheet 2 and the top cover plate 3 are properly accommodated without shaking. Since the outer insulation ring is made of plastic material, the overall material structure is relatively weak, so the protrusion is provided on the outer insulation ring to strengthen the structure and function as a reinforcing rib.

[0041] In some examples, the horizontal width W1 between the end of the top cover plate 3 and the outer wall of the first part 11 and the sum W0 of the horizontal width of the limiting structure and the first part 11 satisfy the relationship W1 / W0 = 68%-80%. The specific range can be set as W1 = 0.3-0.5mm, W0 = 0.5-0.7mm. If the W1 / W0 ratio is too small, W0 becomes large, and the protruding part of the outer insulation ring corresponding to W0 makes it difficult to assemble the explosion-proof sheet 2 and the top cover plate 3 into the outer insulation ring, increasing the assembly difficulty and reducing the production efficiency. If the W1 / W0 ratio is too large, W0 becomes small. Since the material of the outer insulation ring is plastic, the overall strength is relatively low, and the protrusion corresponding to W0 functions as a reinforcing rib. If W0 becomes small, the reinforcing effect will decrease, the outer insulation ring will be easily deformed, and the assembly of the explosion-proof sheet 2 and the top cover plate 3 will be unstable, reducing the reliability of the gas tightness of the cap after sealing.

[0042] In some examples, the relationship between the height H2 of the explosion-proof sheet 2 and the height H0 of the outer insulation ring 1 is H2 / H0 = 18%-28%. The specific range can be set as H0 = 2mm-4mm, H2 = 0.6mm-0.9mm. If the H2 / H0 ratio is too small, H2 is too small, the thickness of the top cover plate 3 and the explosion-proof sheet 2 is too thin, the strength is poor, and deformation is easy to occur, which will affect the stability of the opening pressure of the explosion-proof valve, and the safety performance of the battery will be affected, and the safety will be reduced. If the H2 / H0 ratio is too large, H2 is too large, which will cause the flange (H1) of the outer insulation ring to be shortened beyond H2. After the cap is inserted into the shell, the outer insulation ring has no certain length to be flanged after sealing, which will cause poor air tightness of the battery, and the battery will leak. The safety performance of the battery is reduced.

[0043] The thickness of the outer insulation ring H2 is mainly to accommodate the explosion-proof sheet 2 and the top cover plate 3. By setting the height, the explosion-proof sheet 2 and the top cover plate 3 can be completely accommodated. If the thickness is too small, the top cover plate 3 and the explosion-proof sheet 2 will interfere with the protrusions on the outer insulation ring, causing deformation of the outer insulation ring, and the top cover plate 3 and the explosion-proof sheet 2 cannot be completely accommodated. If the thickness is too large, the distance between the top cover plate 3 and the explosion-proof sheet 2 is too large, which will cause the top cover plate 3 and the explosion-proof sheet 2 to shake inside, affecting the stability and safety performance of the structure.

[0044] In some examples, the relationship between the height H3 of the second part 12 and the height H0 of the outer insulation ring 1 is H3 / H0 = 20%-32%. The specific range can be set as H0 = 2mm-4mm, H3 = 0.8mm-1mm. If the H3 / H0 ratio is too small, H3 becomes small. In order to ensure the air tightness and stability of the battery, the outer insulation ring needs to be compressed during the rolling groove sealing. After the cap is inserted into the shell and sealed, the steel shell rolling groove will extrude the lower part (H3) of the outer insulation ring, and a certain amount of compression will be achieved to ensure the sealing pressure resistance of the battery. When H3 becomes small, the outer insulation ring does not have enough thickness to be compressed by the steel shell rolling groove, which will cause poor air tightness and unstable sealing pressure resistance of the battery, increase the probability of battery leakage during travel, and increase the safety risk of the battery.

[0045] In some examples, the vertical height H1 between the top surface of the first portion 11 and the top surface of the top cover plate 3 is related to the height H0 of the outer insulation ring 1 as follows: H1 / H0 = 45%-60%. The specific range can be set as: H0 = 2mm-4mm, H1 = 1.5mm-2mm. If the H1 / H0 ratio is too small, H1 becomes small, and the amount of flanging when the outer insulation ring is sealed becomes small. After the cap is inserted into the shell, the outer insulation ring has no certain length to be flanged after sealing, which can cause poor airtightness of the battery, liquid leakage of the battery, and decline of the safety performance of the battery. If the H1 / H0 ratio is too large, H1 becomes large, and the amount of flanging becomes large. After sealing, the flanging of the outer insulation ring can interfere with the boss of the top cover plate 3 on the battery cap, causing poor sealing, poor airtightness, battery leakage, and decline of the safety performance of the battery.

[0046] In some examples, the height H21 of the top cover plate 3 is related to the height H22 of the explosion-proof sheet 2 as follows: H21 / H22 = 95%-125%. The specific range can be set as: H21 = recommended range 0.3mm-0.5mm, H22 = 0.25mm-0.45mm. If the H21 / H22 ratio is too small, H21 becomes small and H22 becomes large. The thickness of the top cover plate 3 becomes small, and the strength becomes low. When welding Basbar, the boss of the top cover plate 3 can collapse, which can cause problems such as explosion point and virtual welding during welding. If the H21 / H22 ratio is too large, H21 becomes large and H22 becomes small. The top cover plate 3 is too thick, and the difficulty of stretching the corresponding height of the boss of the top cover plate 3 increases. The stability of the molding becomes poor, the manufacturing cost rises, H22 becomes small, the explosion-proof sheet 2 becomes thin, the strength of the explosion-proof sheet 2 decreases, the opening valve pressure is unstable, and the safety performance of the battery becomes poor.

[0047] In some examples, the second portion 12 immediately adjacent to the explosion-proof sheet 2 is provided with a groove 13 for storing glue. The groove 13 is mainly used for the storage of glue for the adhesion of the explosion-proof sheet 2 and the outer insulation ring. By injecting glue into the groove 13, after the cap is inserted into the shell and the sealing is completed, the glue in the groove 13 of the cap is squeezed out and applied to the contact surface of the explosion-proof sheet 2 and the outer insulation ring due to the pressure on the cap. The excess glue is still stored in the groove 13, so that there is no excess glue to overflow into the battery, which can affect the performance of the battery, and the performance of the battery is guaranteed.

[0048] In some examples, the longitudinal cross-sectional area S10 of the groove 13 is 0.04-0.1mm 2If the area of S10 is too large, the amount of stored glue will be too much, but the amount of glue squeezed out by the cap is constant, and the remaining glue is still stored in the groove 13, causing waste. If the area of S10 is too small, the amount of stored glue is too small, the cap is squeezed, but there is not enough glue to be squeezed out, so that the bonding surface of the external insulation ring and the explosion-proof sheet 2 cannot be completely covered by the glue, the adhesion effect of the explosion-proof sheet 2 and the external insulation is poor, and the cap is scrapped due to shaking, vibration and other factors during transportation / handling, causing the cap top plate 3 and the explosion-proof sheet 2 to separate in the external insulation ring, causing the cap to be scrapped.

[0049] In some examples, the inner bottom of the second part 12 extends radially inward to form an annular extension 14. Even if the glue spills out from the upper end surface edge of the groove 13 due to excessive extrusion of the external insulation ring 12, the spilled glue can only flow to the upper end surface of the extension 14, and will not directly flow onto the battery core, increasing safety. The external insulation ring 1 needs a certain length to ensure the sealing effect during mechanical sealing and to ensure the sealing performance of the battery, but due to the mechanical sealing time, the external insulation ring 1 will be extruded, causing the material of the external insulation ring 1 to spread outward, and the upper space of the extension 14 can accommodate the extended material, without the whole material spreading outward to interfere with other components.

[0050] In some examples, the top of the explosion-proof sheet 2 is provided with an upper boss 21, an outer circumferential groove 24, and a center groove 25 from inside to outside, and the bottom of the explosion-proof sheet 2 is provided with a lower boss 23 and a lower protrusion 22 from inside to outside. The upper boss 21 abuts against the top cover plate 3 for limiting the top cover plate 3 in the horizontal direction. The outer circumferential groove 24 and the center groove 25 are both explosion-proof valve openings, which can quickly and effectively open at the notch of the explosion-proof sheet to release pressure when the internal pressure of the battery exceeds the preset value, thereby improving the safety of the battery. The center groove 25 also has the effect of stress relief, as the explosion-proof sheet is a material with a certain thickness thinned to the present thickness, so the density of the material is high and the stress is concentrated. In order to solve the stability problem of the explosion-proof valve opening, a center groove 25 is provided in the middle, which solves the stress and also has the effect of explosion-proof valve opening, increasing safety. The middle lower boss 23 can be in full contact with the upward protruding middle part of the lower end plate 5, reducing the problem of explosion points and virtual welding during welding. The middle lower boss 23 can increase the strength of the center groove of the explosion-proof sheet. The setting of the lower boss 23 can better control the flatness and reduce the problem of virtual welding and explosion points during welding, increasing the reliability of welding. The lower protrusion 22 is used for installing the inner rubber ring 4.

[0051] As Figure 4As shown, the utility model embodiment provides a cap assembly, including outer insulating ring 1, explosion -proof sheet 2, top cover plate 3, inner rubber ring 4 and lower end plate 5. Inner rubber ring 4 is fixed in the bottom of explosion -proof sheet 2 by the lower protruding 22 on explosion -proof sheet 2, and lower end plate 5 is fixed in the bottom of inner rubber ring 4 by the clamping groove of outer periphery of inner rubber ring 4. The function of inner rubber ring 4 is mainly to isolate explosion -proof sheet and lower end plate, and the boss of explosion -proof sheet and the boss of lower end plate are connected by welding, and other parts are not contacted, in order to guarantee the safety performance of battery, if the short circuit or other thermal runaway problem of battery occurs, the CID power of lower end plate 5 is cut off, and the battery is protected by power failure, but if there is no inner rubber ring, lower end plate 5 is still in contact with explosion -proof sheet after cutting off, and contact current is generated, and the battery will continue to react, and the safety performance of battery is reduced. The function of lower end plate 5 is: welding positive current collector, playing a role of connecting upper and lower, connecting the internal current of battery and cap, and the CID power protection mechanism on lower end plate is one of the protection mechanisms of battery, and the multiple protection mechanisms on cap make the battery safer and safer.

[0052] Based on a general inventive concept, the utility model embodiment provides a cylindrical battery, including the cap assembly in the technical scheme.

[0053] According to the description and drawings of the utility model, those skilled in the art can easily manufacture or use the cap assembly and cylindrical battery of the utility model, and the positive effects described in the utility model can be generated.

[0054] Unless otherwise specified, in the utility model, if there are terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", the orientation or positional relationship indicated by the drawings is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore, the terms describing the orientation or positional relationship in the utility model are only used for example, and cannot be understood as a limitation on the patent, for those skilled in the art, the specific meaning of the above terms can be understood in combination with the drawings and according to the specific situation.

[0055] Unless clearly and specifically defined and limited, in the present application, the terms "set", "connected", and "connection" should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium; can be internal communication of two elements.

[0056] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change of the above embodiment according to the technical essence of the present application falls within the protection scope of the present application.

Claims

1. A cap assembly, characterized by The outer insulation ring (1) comprises a first part (11) and a second part (12) arranged perpendicularly to each other. The explosion-proof sheet (2) is arranged on the second part (12) and is perpendicular to the first part (11). The top cover plate (3) is arranged on the top of the explosion-proof sheet (2) and is perpendicular to the first part (11). The end of the explosion-proof sheet (2) is flush with the end of the top cover plate (3), and both ends are in contact with the first part (11). The first part (11) is provided with a limiting structure for limiting and fixing the explosion-proof sheet (2) and the top cover plate (3) on the outer insulation ring (1). The relationship between the height H2 of the explosion-proof sheet (2) and the top cover plate (3) and the height H0 of the outer insulation ring (1) is H2 / H0 = 18%-28%.

2. The cap assembly of claim 1, wherein The relationship between the height H3 of the second part (12) and the height H0 of the outer insulation ring (1) is H3 / H0 = 20%-32%.

3. The cap assembly of claim 1, wherein The relationship between the vertical height H1 between the top surface of the first part (11) and the top surface of the top cover plate (3) and the height H0 of the outer insulation ring (1) is H1 / H0 = 45%-60%.

4. The cap assembly of claim 1, wherein The relationship between the horizontal width W1 between the end of the top cover plate (3) and the outer wall of the first part (11) and the sum W0 of the horizontal width of the limiting structure and the first part (11) is W1 / W0 = 68%-80%.

5. The cap assembly of claim 1, wherein The relationship between the height H21 of the top cover plate (3) and the height H22 of the explosion-proof sheet (2) is H21 / H22 = 95%-125%.

6. The cap assembly of claim 1, wherein, A groove (13) for storing glue solution is arranged on the top of the second part (12) close to the explosion-proof sheet (2).

7. The cap assembly of claim 1, wherein The limiting structure is a protrusion formed by the inner wall of the first part (11) protruding radially inward of the outer insulation ring (1).

8. The cap assembly of claim 7, wherein, The longitudinal cross-sectional area S10 of the recess (13) is 0.04-0.1 mm 2 .

9. The cap assembly of claim 1, wherein, The cap assembly comprises the cap assembly of any one of claims 1-9.

10. A cylindrical battery, characterized by comprising: ​

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