Positive electrode end coating structure and cylindrical secondary battery

Abstract

The utility model relates to the technical field of cylindrical battery enveloping, and provides a positive electrode end enveloping structure and a cylindrical secondary battery, the positive electrode end enveloping structure comprises a cover cap, a surface pad and a sleeve, the surface pad is arranged on the cover cap in an abutting manner; the sleeve is used for wrapping a shell, a flanging part is integrally formed at one end of the sleeve, the flanging part wraps the outer edge of the side, away from the cover cap, of the face pad, and the flanging part and the face pad are each of an annular structure; the radius of the end face of the sleeve is R0, the ring width of the flanging part is L1, and 20% R0 < = L1 < = 38% R0. According to the utility model, the surface pad is arranged between the cap and the flanging part, so that the insulation performance of the positive electrode and the negative electrode of the battery can be improved, the coating area of the flanging part on the positive electrode end of the battery can be increased, and the problem of poor coating can be avoided by limiting the coating area of the flanging part; and the weight and the processing cost of the battery can be reduced, the energy density of the battery is improved, and the attractiveness of the battery is improved.

Description

Technical Field

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

[0002] With the continuous development of new energy technologies, batteries, as high-efficiency energy storage devices, are widely used in various portable electronic products, electric vehicles, and large-scale energy storage systems. Among them, cylindrical batteries have gradually become one of the mainstream products in the market due to their excellent performance and high energy density.

[0003] Coating is an important step in the production process of cylindrical batteries. By wrapping an insulating material around the outer surface of the battery, micro-short circuits caused by potential differences in the casing or air adhesion can be effectively prevented during charging and discharging, thereby ensuring the normal operation and lifespan of the battery.

[0004] For example, the invention patent with publication number CN107994140A discloses a removable heat-shrink tubing for cylindrical lithium-ion batteries. This tubing covers the outside of the battery casing, with the end of the tubing abutting against the end of the battery for safety protection. However, heat-shrink tubing is heat-shrinkable. If the coverage area of ​​the heat-shrink tubing on the battery end is too small, the end of the tubing will shrink due to the heat generated by the battery, resulting in poor coverage. Conversely, if the coverage area is too large, it will not only increase the weight and processing cost of the battery but also affect its energy density and aesthetics. Utility Model Content

[0005] In view of this, the present invention proposes a positive terminal coating structure and a cylindrical secondary battery, which can provide good safety protection for the positive terminal of the battery by the flange, ensuring the normal use of the battery.

[0006] The technical solution of this utility model is achieved as follows: On the one hand, this utility model provides a positive end coating structure, including a cap, a face pad, and a sleeve, wherein,

[0007] The face pad is abutted against the cap;

[0008] The sleeve is used to cover the shell. One end of the sleeve is integrally formed with a flange. The flange covers the outer edge of the pad on the side away from the cap. Both the flange and the pad are annular structures.

[0009] The end face radius of the sleeve is R0, and the circumference width of the flange is L1, wherein 20% R0≤L1≤38% R0.

[0010] Based on the above technical solutions, preferably, the difference between the inner diameter of the flange and the inner diameter of the mat is L2, wherein 6% R0 ≤ L2 ≤ 22% R0.

[0011] Based on the above technical solutions, preferably, the cap includes a top cover plate, a protective plate, and supporting feet, wherein,

[0012] The top cover plate is fixedly installed inside the housing, and has a vent hole inside;

[0013] The protective plates are spaced apart on one side of the top cover plate and correspond to the positions of the vent holes;

[0014] The support foot is fixedly disposed between the protective plate and the top cover plate, and extends through the surface pad. The minimum distance between the support foot and the surface pad is L3, wherein 3% R0≤L3≤12% R0.

[0015] More preferably, the minimum distance between the vent hole and the surface pad is L4, wherein 5% R0 ≤ L4 ≤ 20% R0.

[0016] More preferably, the minimum distance between the vent hole and the flange is L5, wherein 20% R0 ≤ L5 ≤ 35% R0.

[0017] More preferably, the minimum distance between the support foot and the flange is L6, wherein 16% R0 ≤ L6 ≤ 28% R0.

[0018] Based on the above technical solutions, the preferred value is L1 = 2mm - 4mm.

[0019] For an even more preferred value, L2 = 0.8mm-2.4mm.

[0020] Further preferred values ​​are L3 = 0.4mm-1.2mm and L4 = 0.5mm-2mm.

[0021] Secondly, this utility model provides a cylindrical secondary battery, including the above-mentioned positive terminal coating structure.

[0022] The positive electrode coating structure and cylindrical secondary battery of this invention have the following advantages over the prior art:

[0023] (1) By setting a pad between the cap and the flange, the insulation performance of the positive and negative electrodes of the battery can be improved, and the coverage area of ​​the flange on the positive electrode of the battery can be increased. By limiting the coverage area of ​​the flange, the problem of poor coverage can be avoided, the weight and processing cost of the battery can be reduced, the energy density of the battery can be increased, and the aesthetics of the battery can be improved.

[0024] (2) By restricting the positional and dimensional relationships of the flange, face pad and cap, the flange can provide more reliable protection for the positive terminal of the battery, ensuring the normal use of the battery and improving the assembly efficiency of the battery. Attached Figure Description

[0025] 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.

[0026] Figure 1 This is a top view of a positive end coating structure of this utility model;

[0027] Figure 2 This is a partial top view of a positive-end encapsulation structure of this utility model;

[0028] Figure 3 This is a top view of the cap portion in a positive-end encapsulation structure of this utility model;

[0029] Figure 4 This is a cross-sectional view of the casing of a cylindrical secondary battery according to the present invention.

[0030] The components are: 1. Shell; 2. Cap; 21. Top cover plate; 22. Protective plate; 23. Support foot; 201. Vent hole; 3. Face pad; 4. Sleeve; 41. Flanged edge. Detailed Implementation

[0031] The technical solutions of this utility model will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0032] Cylindrical batteries are divided into cylindrical primary batteries and cylindrical secondary batteries. Due to their advantages such as good consistency, high energy density and good heat dissipation, they have been widely used in electronic equipment, industrial equipment, energy storage and transportation.

[0033] This utility model discloses a cylindrical secondary battery, including a shell 1 and a positive terminal coating structure. The positive terminal coating structure includes a cap 2, a face pad 3, and a sleeve 4. The cap 2 is fixedly disposed at the opening of the shell 1. The face pad 3 is abutted against the outside of the cap 2. The sleeve 4 covers the shell 1, and both ends of the sleeve 4 are flanged and respectively cover the outer edge of the face pad 3 away from the cap 2 and the outer edge of the bottom of the shell 1.

[0034] Sleeve 4 is usually made of PET heat shrink tubing. PET heat shrink tubing, also known as polyester heat shrink tubing, is not only environmentally friendly and non-toxic, but also has good mechanical strength, high temperature resistance and electrical insulation properties.

[0035] By covering the housing 1 and the pad 3 with a sleeve 4, a physical protection can be provided for the battery. The sleeve 4 provides a physical barrier for the battery, which can effectively reduce mechanical damage such as collision, friction and squeezing that the battery suffers during transportation, installation and use, and extend the battery's service life.

[0036] Secondly, the sleeve 4 has good physical sealing and electrical insulation properties. It can not only prevent dust and moisture and other impurities from entering the battery, avoiding problems such as short circuits and corrosion inside the battery, but also electrically isolate the positive and negative terminals of the battery to avoid safety accidents such as short circuits and leakage, thus improving the safety of battery use.

[0037] like Figure 1 As shown, the pad 3 has a ring-shaped structure with a through hole inside, through which the cap 2 can be connected to the electrodes of electrical equipment or other batteries.

[0038] One end of the sleeve 4 is integrally formed with a flange 41, which covers the outer edge of the pad 3 away from the cap 2. The flange 41 is also a ring structure, which not only facilitates the processing of the flange 41, but also prevents the flange 41 from blocking the connection between the cap 2 and the electrical equipment and other electrodes, thus ensuring the normal use of the battery.

[0039] In a cylindrical secondary battery, the outer ring of the flange 41 is circular due to the shape of the casing 1. In order to improve the uniformity of the flange 41 and the consistency of the battery, and to improve the processing efficiency of the flange 41, in some embodiments, the flange 41 is preferably made into an annular shape.

[0040] Furthermore, the face pad 3 is preferably configured to be annular, and the face pad 3 is coaxially arranged with the flange 41, the cap 2 and the housing 1.

[0041] like Figure 1 and Figure 2As shown, the end face radius of the sleeve 4 is R0, which is the end face radius of the entire battery; the circumference width of the flange 41 is L1, which is the radial length of the flange 41 along the end face of the bottom of the shell 1 on the end face of the shell 1; the difference in inner diameter between the flange 41 and the pad 3 is L2. The flange 41 covers the outer edge of the pad 3. The inner diameter of the flange 41 is larger than the inner diameter of the pad 3. Therefore, the difference in inner diameter between the flange 41 and the pad 3 is L2, which is the length of the pad 3 extending outside the flange 41.

[0042] In some embodiments, 20% R0 ≤ L1 ≤ 38% R0, meaning the circumferential width of the flange 41 is 20%, 28%, 30%, or 38% of the radius of the entire battery end face. During cyclic charging and discharging, the battery generates heat, especially at both ends, where the heat generation problem is more severe, causing the flange 41 to shrink due to heat. If L1 < 20% R0, the circumferential width of the flange 41 is too small, resulting in a relatively small coverage area of ​​the flange 41 on the positive terminal of the battery. When the flange 41 shrinks due to heat, the coverage area on the positive terminal will further decrease, leading to poor coverage. If L1 > 38% R0, the circumferential width of the flange 41 is too large, resulting in an excessively large coverage area on the positive terminal of the battery. This not only affects the overall aesthetics of the battery but also increases the cost and weight of the battery, reducing its energy density.

[0043] In some embodiments, R0 = 10.58 mm, L1 = 2 mm - 4 mm, that is, the circumference width of the flange 41 is 2 mm, 3 mm, or 4 mm, etc. During the cyclic charging and discharging process, the battery generates heat, especially at both ends, where the heat generation problem is more severe, causing the flange 41 to shrink due to heat. If L1 < 2 mm, the circumference width of the flange 41 is too small, and the coverage area of ​​the flange 41 on the positive terminal of the battery is relatively small. When the flange 41 shrinks due to heat, the coverage area on the positive terminal of the battery will further decrease, resulting in poor coverage. If L1 > 4 mm, the circumference width of the flange 41 is too large, and the coverage area on the positive terminal of the battery is too large, which not only affects the overall aesthetics of the battery but also increases the cost and weight of the battery and reduces its energy density.

[0044] In some embodiments, 6% R0 ≤ L2 ≤ 22% R0, meaning the length of the pad 3 extending beyond the flange 41 is 6%, 12%, 16%, or 22% of the radius of the entire battery end face. If L2 < 6% R0, the length of the pad 3 extending beyond the flange 41 is too small, meaning the overall width of the pad 3 is too small. This not only fails to provide an effective covering area for the flange 41 but also reduces the insulation performance of the positive and negative electrodes of the battery, increasing the risk of short circuits between the positive and negative electrodes. If L2 > 22% R0, the length of the pad 3 extending beyond the flange 41 is too large, meaning the overall width of the pad 3 is too large. The inner diameter of the through hole in the pad 3 is too small, which will interfere with the cap 2, reducing the battery assembly efficiency and the battery assembly yield.

[0045] In some embodiments, R0 = 10.58 mm, L2 = 0.8 mm - 2.4 mm, that is, the length of the pad 3 extending beyond the flange 41 is 0.8 mm, 1.5 mm, or 2.4 mm, etc. If L2 < 0.8 mm, the length of the pad 3 extending beyond the flange 41 is too small, that is, the overall width of the pad 3 is too small. This not only fails to provide an effective covering area for the flange 41, but also reduces the insulation performance of the positive and negative electrodes of the battery, increasing the risk of short circuits between the positive and negative electrodes of the battery. If L2 > 2.4 mm, the length of the pad 3 extending beyond the flange 41 is too large, that is, the overall width of the pad 3 is too large. The inner diameter of the through hole in the pad 3 is too small, which will interfere with the cap 2, reducing the assembly efficiency and the assembly yield of the battery.

[0046] like Figure 3 As shown, the cap 2 includes a top cover plate 21, a protective plate 22, and a support foot 23. The top cover plate 21 is fixedly installed inside the housing 1. The top cover plate 21 has a vent hole 201 inside. When the battery thermally runs away and produces a large amount of gas, the gas inside the battery will break through the explosion-proof sheet and be discharged from the battery through the vent hole 201 to ensure the explosion-proof performance of the battery. In order to avoid damage to the explosion-proof sheet inside the battery by external objects, the protective plate 22 is spaced apart on the side of the top cover plate 21 away from the explosion-proof sheet, so that the position of the protective plate 22 corresponds to the position of the vent hole 201. The support foot 23 is fixedly installed between the protective plate 22 and the top cover plate 21 to realize the fixed connection between the protective plate 22 and the top cover plate 21.

[0047] The face pad 3 abuts against the top cover plate 21. In order to facilitate the connection of the positive terminal of the battery with electrical equipment and other electrodes, the support foot 23 is installed through the face pad 3. The protective plate 22 is close to the side of the face pad 3 away from the top cover plate 21, or the protective plate 22 is flush with the side of the face pad 3 away from the top cover plate 21, or the protective plate 22 extends out of the side of the face pad 3 away from the top cover plate 21.

[0048] The vent 201 is preferably a circular hole structure and is located in the middle of the top cover plate 21. Correspondingly, the protective plate 22 should be a circular plate structure of the same size as the vent 201. The end of the support foot 23 connected to the protective plate 22 is located on the periphery of the protective plate 22, forming a protruding structure. The end of the support foot 23 away from the protective plate 22 is set on the top cover plate 21 and spaced apart from the vent 201 to avoid the support foot 23 affecting the exhaust effect of the vent 201.

[0049] like Figure 1 and Figure 2 As shown, the minimum distance between the support foot 23 and the surface pad 3 is L3, the minimum distance between the vent hole 201 and the surface pad 3 is L4, the minimum distance between the vent hole 201 and the flanged part 41 is L5, and the minimum distance between the support foot 23 and the flanged part 41 is L6.

[0050] In some embodiments, 3% R0 ≤ L3 ≤ 12% R0, meaning the minimum distance between the support foot 23 and the pad 3 is 3%, 8%, or 12% of the radius of the entire battery end face. During battery assembly, there are certain assembly tolerances. If L3 < 3% R0, the pad 3 is too close to the support foot 23, causing interference between them during battery assembly. This not only reduces assembly efficiency but also lowers the battery yield. If L3 > 12% R0, the pad 3 is too far from the support foot 23, meaning the pad 3's circumference is too small. This not only fails to provide effective coverage for the flange 41 but also reduces the insulation performance of the battery's positive and negative electrodes, increasing the risk of short circuits.

[0051] In some embodiments, 5% R0 ≤ L4 ≤ 20% R0, meaning the minimum distance between the inner wall of the vent hole 201 and the face pad 3 is 5%, 10%, 15%, or 20% of the radius of the entire battery end face. During battery assembly, certain assembly tolerances exist. If L4 < 5% R0, the face pad 3 is too close to the vent hole 201 and the protective plate 22. During battery assembly, this not only causes interference between the face pad 3 and the protective plate 22, reducing assembly efficiency and yield, but also obstructs the vent hole 201, affecting the battery's venting performance. If L4 > 20% R0, the face pad 3 is too far from the vent hole 201 and the protective plate 22, meaning the circumference of the face pad 3 is too small. This not only fails to provide effective coverage for the flanged portion 41, but also reduces the insulation performance of the battery's positive and negative electrodes, increasing the risk of short circuits between the positive and negative electrodes.

[0052] In some embodiments, R0 = 10.58 mm, L3 = 0.4 mm - 1.2 mm, and L4 = 0.5 mm - 2 mm. If L3 < 0.4 mm or L4 < 0.5 mm, the pad 3 is too close to the cap 2. When assembling the battery, interference will occur between the pad 3 and the cap 2, which will not only reduce the battery assembly efficiency and the battery assembly yield, but also affect the battery venting efficiency. If L3 > 1.2 mm or L4 > 2 mm, the pad 3 is too far away from the cap 2, that is, the ring width of the pad 3 is too small. It will not only fail to provide an effective covering area for the flange 41, but will also reduce the insulation performance of the positive and negative electrodes of the battery and increase the risk of short circuit between the positive and negative electrodes of the battery.

[0053] In some embodiments, 20% R0≤L5≤35% R0 means that the minimum distance between the inner wall of the vent hole 201 and the flange 41 is 20%, 25%, 30% or 35% of the radius of the entire battery end face. If L5 < 20% R0, then the flanged part 41 is too close to the vent 201 and the protective plate 22, the circumference of the flanged part 41 is too large, and the coverage area of ​​the flanged part 41 on the positive terminal of the battery is too large. This will not only affect the overall aesthetics of the battery, but also increase the cost and weight of the battery and reduce the energy density of the battery. The battery will generate heat during the cycle charging and discharging process, especially at both ends of the battery, where the heat generation problem is more serious, causing the flanged part 41 to shrink due to heat. If L5 > 35% R0, then the flanged part 41 is too far away from the vent 201 and the protective plate 22, the circumference of the flanged part 41 is too small, and the coverage area of ​​the flanged part 41 on the positive terminal of the battery is relatively small. When the flanged part 41 shrinks due to heat, the coverage area of ​​the flanged part 41 on the positive terminal of the battery will further shrink, resulting in poor coverage.

[0054] In some embodiments, 16% R0 ≤ L6 ≤ 28% R0, meaning the minimum distance between the support foot 23 and the flange 41 is 16%, 20%, 24%, or 28% of the radius of the entire battery end face. If L6 < 16% R0, the flange 41 is too close to the support foot 23, the circumference of the flange 41 is too large, and the coverage area of ​​the flange 41 on the positive terminal of the battery is too large. This not only affects the overall aesthetics of the battery but also increases the cost and weight of the battery and reduces its energy density. During the cyclic charging and discharging process, the battery generates heat, especially at both ends, where the heat generation problem is more severe, causing the flange 41 to shrink due to heat. If L6 > 28% R0, the flange 41 is too far from the support foot 23, the circumference of the flange 41 is too small, and the coverage area of ​​the flange 41 on the positive terminal of the battery is relatively small. When the flange 41 shrinks due to heat, the coverage area of ​​the flange 41 on the positive terminal of the battery will further shrink, resulting in poor coverage.

[0055] In some embodiments, R0 = 10.58 mm, L5 = 2 mm - 4 mm, and L6 = 1.4 mm - 3.4 mm. If L5 < 2 mm or L6 < 1.4 mm, the flange 41 is too close to the cap 2, the circumference of the flange 41 is too large, and the coverage area of ​​the flange 41 on the positive terminal of the battery is too large. This not only affects the overall aesthetics of the battery but also increases the cost and weight of the battery and reduces its energy density. The battery generates heat during cyclic charging and discharging, especially at both ends of the battery, where the heat generation problem is more serious, causing the flange 41 to shrink due to heat. If L5 > 4 mm or L6 > 3.4 mm, the flange 41 is too far from the cap 2, the circumference of the flange 41 is too small, and the coverage area of ​​the flange 41 on the positive terminal of the battery is relatively small. When the flange 41 shrinks due to heat, the coverage area of ​​the flange 41 on the positive terminal of the battery will further shrink, resulting in poor coverage.

[0056] In some embodiments, R0 = 10.58 mm, L1 = 3 mm, L2 = 1.6 mm, L3 = 0.8 mm, L4 = 1.3 mm, L5 = 2.9 mm, and L6 = 2.4 mm. At this point, the coverage area of ​​the flanged portion 41 and the area of ​​the face pad 3 are at their optimal values. This allows the flanged portion 41 to provide a good covering effect for the battery, reduces the battery's cost and weight, increases its energy density, and also improves the assembly efficiency of the face pad 3.

[0057] The structural principle of the positive terminal coating structure and cylindrical secondary battery of this utility model is as follows:

[0058] The pad 3 and the flange 41 not only provide a sealed protection between the cap 2 and the housing 1, but also insulate the cap 2 and the housing 1 to prevent short circuits in the battery. By limiting the specifications of the pad 3 and the flange 41, it is possible to avoid poor covering, reduce the weight and processing cost of the battery, increase the energy density of the battery, and enhance the aesthetics of the battery.

[0059] 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 positive electrode end envelope structure, characterized by: The positive electrode end film structure comprises a cap (2), a face pad (3) and a sleeve (4), wherein, the face pad (3) is arranged on the cap (2); the sleeve (4) is used for covering the shell (1), one end of the sleeve (4) is integrally formed with a flange portion (41), the flange portion (41) covers the outer edge position of the side of the face pad (3) away from the cap (2), and the flange portion (41) and the face pad (3) are both annular structures; the end surface radius of the sleeve (4) is R0, and the ring width of the flange portion (41) is L1, wherein 20% R0≤L1≤38% R0.

2. The positive end cap structure of claim 1, wherein: The difference between the flange portion (41) and the inner diameter of the face pad (3) is L2, wherein 6% R0≤L2≤22% R0.

3. The positive end coating structure as described in claim 1, characterized in that: The cap (2) comprises a top cover plate (21), a protective plate (22) and a support leg (23), wherein, the top cover plate (21) is fixedly arranged in the shell (1), and an air release hole (201) is arranged in the inside of the top cover plate (21); the protective plate (22) is arranged on one side of the top cover plate (21) in a spaced manner, and corresponds to the position of the air release hole (201); the support leg (23) is fixedly arranged between the protective plate (22) and the top cover plate (21), and penetrates the face pad (3), and the minimum distance between the support leg (23) and the face pad (3) is L3, wherein 3% R0≤L3≤12% R0.

4. The positive end cap structure of claim 3, wherein: The minimum distance between the air release hole (201) and the face pad (3) is L4, wherein 5% R0≤L4≤20% R0.

5. The positive end cap structure of claim 4, wherein: The minimum distance between the air release hole (201) and the flange portion (41) is L5, wherein 20% R0≤L5≤35% R0.

6. The positive end cap structure of claim 5, wherein: The minimum distance between the support leg (23) and the flange portion (41) is L6, wherein 16% R0≤L6≤28% R0.

7. A positive end cap structure according to any one of claims 1 to 6, wherein: L1=2mm-4mm.

8. The positive end cap structure of claim 2, wherein: L2=0.8mm-2.4mm.

9. A positive end cap structure according to any one of claims 4 to 6, wherein: L3=0.4mm-1.2mm, L4=0.5mm-2mm.

10. A cylindrical secondary battery characterized by comprising: The positive electrode end film structure comprises a cap (2), a face pad (3) and a sleeve (4), wherein, the face pad (3) is arranged on the cap (2); the sleeve (4) is used for covering the shell (1), one end of the sleeve (4) is integrally formed with a flange portion (41), the flange portion (41) covers the outer edge position of the side of the face pad (3) away from the cap (2), and the flange portion (41) and the face pad (3) are both annular structures; the end surface radius of the sleeve (4) is R0, and the ring width of the flange portion (41) is L1, wherein 20% R0≤L1≤38% R0. The difference between the flange portion (41) and the inner diameter of the face pad (3) is L2, wherein 6% R0≤L2≤22% R0. the cap (2) comprises a top cover plate (21), a protective plate (22) and a support leg (23), wherein, the top cover plate (21) is fixedly arranged in the shell (1), and an air release hole (201) is arranged in the inside of the top cover plate (21); the protective plate (22) is arranged on one side of the top cover plate (21) in a spaced manner, and corresponds to the position of the air release hole (201); the support leg (23) is fixedly arranged between the protective plate (22) and the top cover plate (21), and penetrates the face pad (3), and the minimum distance between the support leg (23) and the face pad (3) is L3, wherein 3% R0≤L3≤12% R0. The minimum distance between the air release hole (201) and the face pad (3) is L4, wherein 5% R0≤L4≤20% R0. The minimum distance between the air release hole (201) and the flange portion (41) is L5, wherein 20% R0≤L5≤35% R0. The minimum distance between the support leg (23) and the flange portion (41) is L6, wherein 16% R0≤L6≤28% R0. L1=2mm-4mm. L2=0.8mm-2.4mm. L3=0.4mm-1.2mm, L4=0.5mm-2mm. The positive electrode end film structure comprises a cap (2), a face pad (3) and a sleeve (4), wherein, the face pad (3) is arranged on the cap (2); the sleeve (4) is used for covering the shell (1), one end of the sleeve (4) is integrally formed with a flange portion (41), the flange portion (41) covers the outer edge position of the side of the face pad (3) away from the cap (2), and the flange portion (41) and the face pad (3) are both annular structures; the end surface radius of the sleeve (4) is R0, and the ring width of the flange portion (41) is L1, wherein 20% R0≤L1≤38% R0. The difference between the flange portion (41) and the inner diameter of the face pad (3) is L2, wherein 6% R0≤L2≤22% R0.

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