Battery cap structure and cylindrical secondary battery

Abstract

The utility model provides a kind of battery cap structure and cylindrical secondary battery, belong to cylindrical lithium battery field, including cover plate setting in battery top;Explosion-proof piece is laid in the lower surface of cover plate;Outer insulating ring is wrapped in the edge of cover plate and explosion-proof piece;Shell is sleeved in cover plate, explosion-proof piece and outer insulating ring, shell top wraps the upper and lower ring surface and outer periphery of outer insulating ring;The part of shell wraps the lower ring surface of outer insulating ring is formed with rolling groove, rolling groove is recessed to battery interior, the distance of the innermost end of rolling groove and shell outer surface along the radial direction of battery is the depth of rolling groove, the depth L1 of rolling groove is 15.2%~24.8% of battery radius R.The utility model carries out optimization design to the ratio range of rolling groove depth and battery radius, ensure that rolling groove depth is enough to make outer insulating ring produce enough compression deformation, effectively prevent electrolyte leakage and external pollutant invasion, also avoid the waste of shell material and internal space is excessively occupied due to rolling groove too deep.

Description

Technical Field

[0001] This utility model relates to the field of cylindrical lithium battery technology, and in particular to a battery cap structure and a cylindrical secondary battery. Background Technology

[0002] In the battery assembly process, the grooving structure of the casing is one of the key technological steps to achieve mechanical sealing and internal airtightness. In existing technologies, the casing of a cylindrical battery is formed with an annular groove through a grooving process to fix and press the cap assembly. The depth, shape, and related structural parameters of this groove directly affect the battery's sealing reliability, internal space utilization, energy density, and safety performance.

[0003] In current cylindrical battery designs commonly used in the industry, the depth of the groove in the casing is often not scientifically proportional to the battery radius, relying heavily on empirical settings and lacking systematic theoretical support and optimization verification. If the groove depth is too small, it may result in insufficient compression of the outer insulation ring, failing to achieve effective sealing and posing a risk of electrolyte leakage or external gas intrusion, affecting battery life and safety. If the groove depth is too large, the original height of the casing needs to be increased, leading to material waste. At the same time, the increased groove collapse encroaches on the internal space of the cell, reducing battery energy density and even causing safety hazards such as internal short circuits.

[0004] Therefore, there is an urgent need for a cylindrical secondary battery with a reasonable structural design and scientific parameter matching, which can maximize the use of internal space and improve energy density while ensuring sealing reliability, and at the same time take into account the feasibility and safety of manufacturing process. Utility Model Content

[0005] In view of this, this utility model proposes a battery cap structure and a cylindrical secondary battery to solve the problem of unreasonable groove design in the current battery cap structure.

[0006] The technical solution of this utility model is implemented as follows: This utility model provides a battery cap structure, including a cover plate disposed on the top of the battery; an explosion-proof sheet disposed on the lower surface of the cover plate; an outer insulating ring that wraps around the edges of the cover plate and the explosion-proof sheet; and a shell that is fitted over the cover plate, the explosion-proof sheet, and the outer insulating ring. The top of the shell forms an edge that tightly adheres to the upper and lower annular surfaces and the outer peripheral surface of the outer insulating ring. A groove is formed on the portion of the shell that wraps around the lower annular surface of the outer insulating ring. The groove is recessed into the battery. The distance between the innermost end of the groove facing the inside of the battery and the outer surface of the shell along the radial direction of the battery is the depth of the groove. The depth L1 of the groove is 15.2% to 24.8% of the battery radius R.

[0007] Based on the above technical solutions, preferably, the portion of the outer insulating ring that covers the lower surface of the explosion-proof sheet has a recessed portion, one end of which is connected to the end of the portion of the outer insulating ring that covers the lower surface of the explosion-proof sheet, and the other end of which extends away from the explosion-proof sheet.

[0008] More preferably, it also includes an inner rubber ring, which is laid on the lower surface of the explosion-proof sheet; wherein, a gap is left between the free end of the recessed part and the outer peripheral surface of the inner rubber ring, and the width L2 of the gap along the radial direction of the battery is 3.8%-5.7% of the battery radius R.

[0009] More preferably, the width L3 of the free end of the sunken portion along the radial direction of the battery is 3.8%-5.7% of the battery radius R.

[0010] More preferably, the downward extension direction forms an angle α with the lower surface of the explosion-proof sheet, and the angle α is 8° to 28°.

[0011] More preferably, the width from the free end of the recessed portion to the outer circumferential surface of the outer insulating ring along the battery axis is set as the maximum width L4 of the lower half of the outer insulating ring, and the maximum width L4 of the lower half of the outer insulating ring is 1.8mm to 2.8mm.

[0012] Based on the above technical solutions, preferably, the minimum thickness H1 of the portion of the housing located in the groove is 0.2mm to 0.3mm.

[0013] Based on the above technical solutions, preferably, the maximum height H2 of the groove along the battery axis is 0.6mm to 1.4mm.

[0014] Based on the above technical solutions, preferably, the groove has a cavity inside, and one end of the cavity near the outer surface of the shell is connected to the outside through an opening. The minimum height H3 of the opening position of the cavity along the battery axis is 0.22mm to 0.32mm.

[0015] Secondly, this utility model also provides a cylindrical secondary battery that adopts the above-mentioned battery cap structure.

[0016] This utility model provides a battery cap structure and a cylindrical secondary battery that have the following advantages over existing technologies:

[0017] Beneficial effects:

[0018] (1) This utility model optimizes the ratio range of groove depth to battery radius to ensure that the groove depth is sufficient to cause sufficient compression deformation of the outer insulating ring, forming a reliable seal, effectively preventing electrolyte leakage and external contaminant intrusion, and avoiding waste of shell material and excessive occupation of internal space due to excessive groove depth, thereby maximizing the energy density and capacity of the battery and improving the overall safety and yield of the product.

[0019] (2) The structure of the recessed part of the outer insulating ring and its matching relationship with the surrounding components have been optimized in this utility model. This provides the best buffer space for the outer insulating ring to creep under pressure, which avoids interference with the inner rubber ring and affects its function, and ensures sufficient compression to make the seal more durable and reliable. At the same time, it accurately guides the flow and filling direction of the plastic outer insulating ring under pressure, so that it undergoes moderate and beneficial creep to form a perfect seal. It also avoids the risk of seal failure or short circuit caused by excessive plastic deformation or incorrect creep direction (e.g., interference with the internal core). Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a front sectional view of the battery cap structure of this utility model;

[0022] Figure 2 For the present utility model Figure 1 Enlarged view of point A in the middle;

[0023] Figure 3 For the present utility model Figure 1 Enlarged view of point A in the middle;

[0024] Figure 4 For the present utility model Figure 1 Enlarged view of point A in the middle.

[0025] In the diagram: 1. Cover plate; 2. Explosion-proof sheet; 3. Outer insulating ring; 31. Recessed part; 4. Housing; 41. Groove; 401. Cavity; 5. Inner rubber ring; 501. Gap. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0027] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0028] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. Additionally, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0032] like Figure 1 As shown, combined with Figure 2 The present invention provides a battery cap structure, comprising a cover plate 1, an explosion-proof sheet 2, an outer insulating ring 3, and a housing 4.

[0033] The cover plate 1 is typically made of metal (such as aluminum or aluminum alloy) and is located on top of the battery, serving as the outlet of one of the battery's electrodes (usually the positive electrode). A protrusion may be provided on its upper part for welding connecting tabs (Bar tabs).

[0034] The explosion-proof sheet 2 is laid on the lower surface of the cover plate 1. The explosion-proof sheet 2 is also made of metal. Its core functions are firstly, to serve as part of the current path and realize the "connection between the upper and lower" of the electrical connection; secondly, it is usually designed with an explosion-proof valve (not shown separately in the figure). When the internal pressure of the battery rises abnormally, the explosion-proof valve will rupture and open, thereby releasing the internal pressure and preventing the battery from exploding, playing a key safety protection role.

[0035] The outer insulating ring 3 wraps around the edge of the cover plate 1 and the explosion-proof sheet 2. It is usually made of engineering plastics such as PPS. The main function of the outer insulating ring 3 is mechanical support and insulation to prevent the cover plate 1 from contacting the metal shell 4 and causing a short circuit.

[0036] The casing 4 is cylindrical and fits over the cover plate 1, the explosion-proof sheet 2, and the outer insulating ring 3. A groove 41 is formed on the portion of the casing 4 that covers the lower surface of the outer insulating ring 3, and the groove 41 is recessed into the battery. Specifically, through a rolling process, the top of the casing 4 is rolled inward and plastically deformed to form an inwardly recessed groove 41. This creates a rim on the top of the casing 4 that tightly covers the upper and lower annular surfaces and the outer circumference of the outer insulating ring 3, firmly encapsulating the cap structure within the casing 4 and achieving mechanical fixation and sealing. The distance between the innermost point of the groove 41 facing the battery interior and the outer surface of the casing 4 along the battery radial direction is the depth of the groove 41. The innermost point of the groove 41 facing the battery interior refers to the point of the entire groove 41 structure closest to the battery's central axis. The depth L1 of the groove 41 is 15.2% to 24.8% of the battery radius R. The core improvement of this invention lies in the scientific design and limitation of the depth L1 of the groove 41, which is the optimal balance range obtained by researchers through extensive research and experimental verification.

[0037] If this ratio is too small, it means that the groove 41 depth L1 is too shallow. This will result in insufficient compression on the lower surface of the outer insulating ring 3 during sealing, making it unable to generate enough elasticity or plastic deformation to fully fill the sealing interface. This leads to a decrease in the sealing reliability of the battery and poses a risk of electrolyte leakage or intrusion of external impurities.

[0038] An excessively large ratio means that the groove 41 depth L1 is too deep. To form a sufficiently deep groove 41, the original height of the housing 4 before grooving must be increased accordingly, leading to material waste and increased costs. More importantly, an excessively deep groove 41 will cause its "sag," that is, excessive inward protrusion, which seriously occupies the valuable space inside the battery, squeezing the winding core below. This not only reduces the energy density and capacity of the battery, but also increases the risk of short circuit when the winding core comes into contact with the housing 4.

[0039] Therefore, controlling the ratio of the depth L1 of the groove 41 to the battery radius R between 15.2% and 24.8% can balance sealing reliability and internal space utilization of the battery, maximizing the battery's energy density while ensuring battery safety. For example, in this embodiment, the battery radius R is 10.5 mm, and the preferred range of the battery radius R is 9.5 mm to 11.5 mm. The depth L1 of the groove 41 is 2.1 mm, and the preferred range of the depth L1 of the groove 41 is 1.6 to 2.6 mm. Therefore, the depth L1 of the groove 41 is 20% of the battery radius R, which meets the design requirements.

[0040] exist Figure 2 In one optional embodiment shown, the portion of the outer insulating ring 3 covering the lower surface of the explosion-proof sheet 2 has a recessed portion 31. One end of the recessed portion 31 is connected to the end of the portion of the outer insulating ring 3 covering the lower surface of the explosion-proof sheet 2, and the other end of the recessed portion 31 extends away from the explosion-proof sheet 2 (or towards the core inside the battery). This structural design allows the recessed portion 31 to better undergo compression and creep when the outer insulating ring 3 is subjected to the rolling pressure of the housing 4, filling the gap between the cap structure and the housing 4 and forming a more effective seal.

[0041] exist Figure 2 In one alternative embodiment shown, an inner rubber ring 5 is also included.

[0042] The inner rubber ring 5 is laid in the central area of ​​the lower surface of the explosion-proof sheet 2, and its function is to achieve insulation and sealing between the explosion-proof sheet 2 and other components below (such as the lower end plate).

[0043] A gap 501 is left between the free end of the recessed portion 31 and the outer circumference of the inner rubber ring 5. This gap 501 is a key parameter ensuring the long-term reliability of the battery after sealing. The radial width L2 of the gap 501 is 3.8%-5.7% of the battery radius R. If this ratio is too small, it indicates that during the battery sealing process, fluctuations or slight increases in sealing pressure may cause the material from the recessed portion 31 of the outer insulating ring 3 to creep and come into contact with or even interfere with the inner rubber ring 5. This interference could lead to deformation of the inner rubber ring 5, affecting its original sealing and insulation functions, or generating stress during long-term use, affecting sealing stability. If this ratio is too large, it indicates insufficient compression creep of the recessed portion 31 of the outer insulating ring 3 during the sealing process. A small compression amount means a weakened ability to fill gaps and form a reliable seal, which also affects the battery's sealing reliability. Therefore, by controlling the ratio of the radial width L2 of the gap 501 to the battery radius R between 3.8% and 5.7%, a suitable buffer space is provided for the extrusion creep of the outer insulating ring 3. This avoids the risk of interference with the inner rubber ring 5 while ensuring sufficient compression, thereby guaranteeing the process tolerance of the sealing process and the reliability of the final seal. For example, in this embodiment, the battery radius R is 10.5 mm, the radial width L2 of the gap 501 is 0.5 mm, and the preferred range of the radial width L2 of the gap 501 is 0.4 to 0.6 mm. Therefore, the radial width L2 of the gap 501 is 4.8% of the battery radius R, which meets the design requirements.

[0044] exist Figure 2In one optional embodiment shown, the width L3 of the free end of the recessed portion 31 along the radial direction of the battery is 3.8%-5.7% of the battery radius R. The width L3 of the free end of the recessed portion 31 along the radial direction of the battery directly reflects its shape and sealing effect after compression creep: if the ratio is too small, it indicates that the creep of the recessed portion 31 of the outer insulating ring 3 is insufficient, and the material fails to fully expand outward to fill the sealing surface, which reflects that its compression is small, resulting in a decrease in the sealing reliability of the battery; if the ratio is too large, it indicates that the creep of the recessed portion 31 of the outer insulating ring 3 is too large. Since the outer insulating ring 3 is a plastic part, excessive compression creep may cause it to change from elastic deformation to irreversible plastic deformation, or even lead to material failure and cracking, which will damage the integrity of the seal and affect the long-term sealing reliability of the battery. Therefore, by controlling the ratio of the width L3 of the free end of the recessed portion 31 along the radial direction of the battery to the battery radius R between 3.8% and 5.7%, moderate and beneficial creep of the recessed portion 31 of the outer insulating ring 3 can be ensured, which can form an effective seal while avoiding the risk of failure due to excessive deformation. For example, in this embodiment, the battery radius R is 10.5 mm, the width L3 of the free end of the recessed portion 31 along the radial direction of the battery is 0.5 mm, and the preferred range of the width L3 of the free end of the recessed portion 31 along the radial direction of the battery is 0.4 to 0.6 mm. Therefore, the width L3 of the free end of the recessed portion 31 along the radial direction of the battery is 4.8% of the battery radius R, which meets the design requirements.

[0045] exist Figure 4 In one optional embodiment shown, the downward extension direction of the recessed portion 31 forms an angle α with the lower surface of the explosion-proof sheet 2. The angle α controls the flow direction of the material in the outer insulating ring 3 after being compressed. If the angle α is too small, the recessed portion 31 extends downward almost parallel to the explosion-proof sheet 2, and the space above it is restricted by the lower surface of the explosion-proof sheet 2. This prevents the material of the outer insulating ring 3 from creeping upward when compressed, thus limiting its effective filling path. If the angle α is too large, the recessed portion 31 extends downward too steeply, causing the material of the outer insulating ring 3 to creep mainly into the internal space of the battery when compressed. This may not only fail to effectively fill the intended sealing surface, but more seriously, the creeping material may come into contact with and interfere with the core inside the battery, causing core compression and increasing the risk of short-circuit failure. Therefore, a reasonable angle α of 8° to 28° can optimize the creep direction of the material in the outer insulating ring 3, enabling it to effectively fill laterally and circumferentially, forming a uniform and reliable seal, while avoiding interference with the internal structure. For example, in this embodiment, the included angle α is 18°.

[0046] exist Figure 2In one optional embodiment shown, the width from the free end of the recessed portion 31 to the outer circumferential surface of the outer insulating ring 2 along the battery axis is set as the maximum width L4 of the lower half of the outer insulating ring 2, which is 1.8mm to 2.8mm. The maximum width L4 of the lower half of the outer insulating ring 2 is a key parameter for measuring the structural dimensions of the lower half of the outer insulating ring 3. If this maximum width is too small, it means that the amount of solid material in the lower half of the outer insulating ring 3 is insufficient, and its strength and compressible sealing volume are limited, making it difficult to guarantee long-term stable sealing reliability. If this maximum width is too large, it means that the volume of the lower half of the outer insulating ring 3 is too large. When the seal is under pressure, the excess plastic material will creep downwards, which also poses a risk of interference with the internal core of the battery, potentially leading to a short circuit. Therefore, optimizing the design range of the maximum width L4 of the lower half of the outer insulating ring 2 can ensure sufficient sealing material while preventing encroachment on the internal space.

[0047] exist Figure 3 In one optional embodiment shown, the minimum thickness H1 of the portion of the housing 4 located in the groove 41 is 0.2mm to 0.3mm. The minimum thickness H1 of the portion of the housing 4 located in the groove 41 directly affects the mechanical strength and airtightness of the seal. If the thickness is too small, it means that the housing 4 at the groove 41 position is too thin, resulting in insufficient mechanical strength at the groove 41 position. Consequently, during the sealing process, the enormous pressure may cause undesirable deformation of the shape of the groove 41 (such as further flattening), making it unable to effectively press and fix the internal cap structure and sealing ring, thus compromising the airtightness of the battery. While a thickness that is too large provides sufficient strength, it increases the overall weight of the housing 4, reducing the battery's energy density; furthermore, thicker materials require greater rolling pressure, increasing the difficulty of the groove sealing process. Therefore, optimizing the design range of the minimum thickness H1 of the portion of the housing 4 located in the groove 41 can balance the battery's energy density and manufacturability while ensuring sealing strength and sealing performance.

[0048] exist Figure 3 In one optional embodiment shown, the maximum height H2 of the groove 41 along the battery axial direction is 0.6 mm to 1.4 mm. The maximum height H2 of the groove 41 along the battery axial direction relates to the total battery height and internal space. If the height is too small, the groove 41 structure is too flat, and its mechanical locking capability may be insufficient; moreover, a flat groove 41 is more prone to "collapse" under internal pressure, encroaching on internal space and increasing the risk of short circuits. If the groove 41 structure is too large, the structure will appear too bulging, thus significantly increasing the total battery height, or the height of the internal core must be compressed to maintain the total height. In either case, this will lead to a decrease in battery capacity and a sacrifice in energy density. Therefore, optimizing the design range of the maximum height H2 of the groove 41 along the battery axial direction can ensure sufficient mechanical locking force while minimizing the occupation of effective internal space in the battery.

[0049] exist Figure 3 In one optional embodiment shown, the groove 41 has a cavity 401 inside. One end of the cavity 401 near the outer surface of the housing 1 is connected to the outside through an opening. The minimum height H3 of the opening position of the cavity 401 along the battery axial direction is 0.22mm to 0.32mm. The minimum height H3 of the opening position of the cavity 401 along the battery axial direction is one of the fine parameters reflecting the internal shape of the groove 41, affecting the stability of the groove 41 structure and its internal space. If the opening is too narrow, this sharp structure is more prone to plastic deformation (collapse) under stress, thereby encroaching on the internal space of the battery and increasing the risk of short circuit. If the opening is too large, the effect is similar to that of an excessively large maximum height H2 of the groove 41 along the battery axial direction, which will occupy too much axial space and is not conducive to battery miniaturization and high energy density. Therefore, optimizing the design range of the minimum height H3 of the opening position of the cavity 401 along the battery axial direction can optimize the structural stability of the groove, prevent its deformation, and reduce space waste.

[0050] like Figure 1 As shown, the present invention provides a cylindrical secondary battery that adopts a battery cap structure according to any of the above embodiments.

[0051] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A battery cap structure, characterized in that, include: A cover plate (1) is disposed on the top of the battery; An explosion-proof sheet (2) is laid on the lower surface of the cover plate (1); An outer insulating ring (3) surrounds the edges of the cover plate (1) and the explosion-proof sheet (2) in a rim-like manner; The housing (4) is fitted over the cover plate (1), the explosion-proof sheet (2), and the outer insulating ring (3). The top of the housing (4) forms a rim that closely covers the upper and lower annular surfaces and the outer circumferential surface of the outer insulating ring (3); the portion of the housing (4) covering the lower annular surface of the outer insulating ring forms a groove (41), the groove (41) is recessed into the battery, and the distance between the innermost end of the groove (41) facing the inside of the battery and the outer surface of the housing (4) along the radial direction of the battery is the depth of the groove (41), and the depth L1 of the groove (41) is 15.2% to 24.8% of the battery radius R.

2. The battery cap structure according to claim 1, characterized in that: The portion of the outer insulating ring (3) that covers the lower surface of the explosion-proof sheet (2) has a recessed portion (31). One end of the recessed portion (31) is connected to the end of the portion of the outer insulating ring (3) that covers the lower surface of the explosion-proof sheet (2), and the other end of the recessed portion (31) extends away from the explosion-proof sheet (2).

3. The battery cap structure according to claim 2, characterized in that, Also includes: An inner rubber ring (5) is applied to the lower surface of the explosion-proof sheet (2); Wherein, a gap (501) is left between the free end of the sunken part (31) and the outer peripheral surface of the inner rubber ring (5), and the width L2 of the gap (501) along the radial direction of the battery is 3.8%-5.7% of the battery radius R.

4. The battery cap structure according to claim 2, characterized in that: The width L3 of the free end of the sunken portion (31) along the radial direction of the battery is 3.8%-5.7% of the battery radius R.

5. The battery cap structure according to claim 2, characterized in that: The downward extension direction of the recessed part (31) forms an angle α with the lower surface of the explosion-proof sheet (2), and the angle α is 8° to 28°.

6. The battery cap structure according to claim 2, characterized in that: The width from the free end of the recessed portion (31) to the outer circumferential surface of the outer insulating ring (2) along the battery axis is set as the maximum width L4 of the lower half of the outer insulating ring (2), and the maximum width L4 of the lower half of the outer insulating ring (2) is 1.8mm to 2.8mm.

7. The battery cap structure according to claim 1, characterized in that: The minimum thickness H1 of the portion of the housing (4) located in the groove (41) is 0.2 mm to 0.3 mm.

8. The battery cap structure according to claim 1, characterized in that: The maximum height H2 of the groove (41) along the battery axis is 0.6mm to 1.4mm.

9. A battery cap structure according to claim 1, characterized in that: The groove (41) has a cavity (401) inside. One end of the cavity (401) near the outer surface of the shell (1) is connected to the outside through an opening. The minimum height H3 of the opening position of the cavity (401) along the battery axis is 0.22mm to 0.32mm.

10. A cylindrical secondary battery, characterized in that: The battery cap structure described in any one of claims 1 to 9 is adopted.

Images