Battery explosion-proof sheet and secondary battery

Abstract

The utility model provides a battery explosion-proof piece and a secondary battery, the battery explosion-proof piece is made of steel, the battery explosion-proof piece comprises a first plane part and a convex part, the first plane part is arranged at the periphery of the convex part, and the convex part is arranged at the periphery of the first plane part; the protruding part is formed by sinking from the first end face of the first plane part to the second end face of the first plane part in the thickness direction of the battery anti-explosion piece, and the end, away from the first end face, of the protruding part in the thickness direction of the battery anti-explosion piece protrudes out of the second end face in the thickness direction of the battery anti-explosion piece; the first plane part is provided with a welding area, one end face of the protruding part in the thickness direction of the battery anti-explosion piece is provided with an anti-explosion nick, and the depth of the anti-explosion nick is smaller than the wall thickness of the protruding part. The first plane part and the protruding part are arranged in the thickness direction of the battery anti-explosion piece in a staggered mode, so that heat generated by welding in the welding area on the first plane part can be effectively prevented from being transmitted to the anti-explosion nick in the protruding part, deformation of the anti-explosion nick is prevented, and failure of the battery anti-explosion piece is prevented.

Description

Technical Field

[0001] This utility model relates to the field of power battery technology, and in particular to a battery explosion-proof sheet and a secondary battery. Background Technology

[0002] For safety reasons, during the manufacturing process of secondary batteries (such as lithium-ion batteries), explosion-proof valves are installed on the battery cover or battery casing. The explosion-proof valve contains an explosion-proof disc with grooves. The grooves are the weakest points of the explosion-proof disc. When the internal pressure of the battery reaches a certain value, the explosion-proof disc opens at the weakest groove, releasing the internal pressure of the battery and preventing the internal pressure from increasing further and causing the battery to explode.

[0003] Existing explosion-proof sheets are generally flat, sheet-like structures. When the explosion-proof sheet is welded to the battery cover or battery casing, the heat generated during welding can easily be transferred to the scored areas, causing deformation at the weak scored areas and ultimately leading to the failure of the explosion-proof sheet. Moreover, the thinner the explosion-proof sheet, the more prone it is to this problem. Utility Model Content

[0004] The technical problem to be solved by this utility model is to overcome the defect that the planar explosion-proof sheet in the prior art is easy to transfer welding heat to the groove, causing deformation at the groove and resulting in failure of the explosion-proof sheet, and to provide a battery explosion-proof sheet and a secondary battery.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution:

[0006] A battery explosion-proof sheet is made of steel. The battery explosion-proof sheet includes a first flat portion and a protruding portion. The first flat portion is disposed on the outer periphery of the protruding portion. The first flat portion has a first end face and a second end face that are spaced apart in the thickness direction of the battery explosion-proof sheet. The protruding portion is recessed from the first end face along the thickness direction of the battery explosion-proof sheet toward the second end face. One end of the protruding portion away from the first end face in the thickness direction of the battery explosion-proof sheet protrudes beyond the second end face along the thickness direction of the battery explosion-proof sheet.

[0007] The first planar portion is provided with a welding area, which is used for welding to the battery cover or battery casing;

[0008] The protrusion has an explosion-proof groove on one end face in the thickness direction of the battery explosion-proof sheet, and the depth of the explosion-proof groove is less than the wall thickness of the protrusion.

[0009] In this solution, a protrusion is formed on the battery explosion-proof sheet, so that the welding area and the explosion-proof markings of the battery explosion-proof sheet are located in different parts of the battery explosion-proof sheet. The first flat part and the protrusion are staggered in the thickness direction of the battery explosion-proof sheet, which can effectively prevent the heat generated by welding at the welding area on the first flat part from being transferred to the explosion-proof markings on the protrusion, prevent deformation at the explosion-proof markings, and prevent the battery explosion-proof sheet from failing.

[0010] Preferably, the wall thickness d1 of the first planar portion is 0.1~0.2 mm; and / or, the wall thickness d2 of the protrusion is 0.1~0.2 mm.

[0011] In this solution, since the structural strength of steel is greater than that of aluminum, the wall thickness of the battery explosion-proof sheet made of steel can be designed to be smaller, so as to reduce the space occupied by the battery explosion-proof sheet. This allows it to be adapted to battery covers or battery casings made of steel with a thinner thickness, reserving more installation space for the battery cells and increasing the battery capacity.

[0012] Preferably, the wall thickness d1 of the first planar portion is equal to the wall thickness d2 of the protrusion.

[0013] In this solution, the above-mentioned configuration allows the first flat portion and the protruding portion to be directly machined from a single sheet of material with uniform thickness, which facilitates the processing of the battery explosion-proof sheet.

[0014] Preferably, when the wall thickness d2 of the protrusion is 0.1~0.2mm, the depth h of the explosion-proof groove is 0.05~0.12mm.

[0015] In this design, the above-mentioned configuration facilitates the timely discharge of gas generated by the battery cell.

[0016] Preferably, the distance d3 between the end face of the protrusion facing the first end face in the thickness direction of the battery explosion-proof sheet and the first end face is 0.2~0.4mm.

[0017] In this design, by controlling the height difference between the first flat portion and the protruding portion within a certain range along the thickness direction of the battery explosion-proof sheet, two advantages are achieved. First, it prevents the heat generated during welding at the welding area from easily transferring to the explosion-proof markings on the protruding portion due to an excessively low height difference, thus preventing deformation of the explosion-proof markings and failure of the battery explosion-proof sheet. Second, it avoids the protruding portion extending excessively into the battery's interior and interfering with the cell due to an excessively high height difference, ensuring the reliability of the secondary battery. Alternatively, it avoids the protruding portion protruding excessively from the battery's exterior and occupying too much space due to an excessively high height difference, thereby making the secondary battery structure more compact.

[0018] Preferably, the welding area is located at the outer peripheral end of the first planar portion, and the shortest distance d4 between the outer peripheral wall of the first planar portion and the outer peripheral wall of the protrusion is greater than or equal to 2 mm.

[0019] In this solution, the above-mentioned arrangement provides sufficient welding space on the first flat surface, ensuring the welding strength between the first flat surface and the battery cover or battery casing. Furthermore, by increasing the distance between the first flat surface and the protrusion, the heat transfer path generated during welding is extended, gradually consuming the heat and resulting in a lower temperature closer to the explosion-proof markings. This further prevents deformation at the explosion-proof markings and avoids failure of the battery explosion-proof sheet.

[0020] Preferably, the battery explosion-proof sheet further includes a second planar portion disposed on the inner periphery of the protrusion. The second planar portion has a third end face and a fourth end face spaced apart in the thickness direction of the battery explosion-proof sheet. The protrusion extends from the third end face toward the fourth end face along the thickness direction of the battery explosion-proof sheet and extends beyond the fourth end face.

[0021] In this solution, a feasible solution for a battery explosion-proof valve is provided. In addition to the overall recessed inner circumference of the first flat portion forming a protrusion, a protrusion can also be formed only around the area with explosion-proof markings, which provides greater design flexibility and a wider range of applications.

[0022] Preferably, the shortest distance d5 between the explosion-proof groove and the inner peripheral wall of the protrusion is greater than or equal to 1 mm.

[0023] In this solution, the above-mentioned settings are used to reserve sufficient processing space for processing explosion-proof markings, so as to facilitate the processing of explosion-proof markings.

[0024] A secondary battery includes a battery cover, a battery housing, and a battery explosion-proof sheet as described above. The battery explosion-proof sheet is fixed to the battery cover or the battery housing and covers the explosion-proof holes on the battery cover or the battery housing.

[0025] In this solution, the battery explosion-proof plate is used to prevent the internal power of the secondary battery from increasing the pressure and causing an explosion. When the internal pressure of the secondary battery is too high, the battery explosion-proof plate can be ruptured to release the internal pressure of the secondary battery and reduce the risk of explosion.

[0026] Preferably, the protrusion faces the interior of the secondary battery and extends into the interior of the explosion-proof hole.

[0027] In this design, the above-mentioned features prevent the protrusion from being exposed on the battery cover or battery casing, making it less likely for the protrusion to interfere with other structures and facilitating the assembly of the secondary battery.

[0028] The positive and progressive effects of this utility model are as follows: by forming a protrusion on the battery explosion-proof sheet, the welding area and the explosion-proof markings of the battery explosion-proof sheet are located in different parts of the battery explosion-proof sheet. The staggered arrangement of the first flat part and the protrusion in the thickness direction of the battery explosion-proof sheet can effectively prevent the heat generated by welding at the welding area on the first flat part from being transferred to the explosion-proof markings on the protrusion, thus preventing deformation at the explosion-proof markings and preventing the battery explosion-proof sheet from failing. Attached Figure Description

[0029] Figure 1 This is a three-dimensional structural diagram of the battery cover plate according to Embodiment 1 of this utility model.

[0030] Figure 2 This is another three-dimensional structural diagram of the battery cover plate of Embodiment 1 of this utility model.

[0031] Figure 3 This is a three-dimensional structural diagram of the battery cover plate according to Embodiment 1 of this utility model.

[0032] Figure 4 This is a three-dimensional structural diagram of the battery explosion-proof sheet of Embodiment 1 of this utility model.

[0033] Figure 5 This is another three-dimensional structural diagram of the battery explosion-proof sheet of Embodiment 1 of this utility model.

[0034] Figure 6 This is a cross-sectional structural diagram of the battery explosion-proof sheet of Embodiment 1 of this utility model.

[0035] Figure 7 This is a three-dimensional structural diagram of the battery cover plate according to Embodiment 2 of this utility model.

[0036] Figure 8 This is a three-dimensional structural diagram of the battery explosion-proof sheet of Embodiment 2 of this utility model.

[0037] Figure 9 This is a cross-sectional structural diagram of the battery explosion-proof sheet of Embodiment 2 of this utility model.

[0038] Explanation of reference numerals in the attached figures:

[0039] Battery cover 1

[0040] Explosion-proof hole 11

[0041] Battery explosion-proof sheet 2

[0042] First plane section 3

[0043] First end face 31

[0044] Second end face 32

[0045] Protrusion 4

[0046] Groove 41

[0047] Welding area 5

[0048] Explosion-proof scoring 6

[0049] Second plane section 7

[0050] Third end face 71

[0051] Fourth end face 72 Detailed Implementation

[0052] The present invention will be described more clearly and completely below with reference to the accompanying drawings, using a preferred embodiment.

[0053] Example 1

[0054] This embodiment discloses a secondary battery, including a battery cell, a battery cover, and a battery casing. The battery cover and the battery casing constitute the battery shell of the secondary battery and enclose a receiving space for accommodating the battery cell.

[0055] like Figures 1-3 As shown, the battery cover plate 1 is provided with an explosion-proof hole 11. The explosion-proof hole 11 extends through both ends in the thickness direction of the battery cover plate 1. The explosion-proof hole 11 connects the secondary battery's housing space with the outside of the secondary space, so that excessive battery pressure in the housing space can be released through the explosion-proof hole 11, reducing the risk of explosion.

[0056] Furthermore, such as Figure 1 and Figure 2 As shown, the secondary battery also includes a battery explosion-proof plate 2, which is fixed to the battery cover 1 and completely covers the explosion-proof hole 11 on the battery cover 1. When the secondary battery is in normal condition, the battery explosion-proof plate 2 always seals the explosion-proof hole 11 on the battery cover 1 to ensure the airtightness of the secondary battery. When the power in the containment space increases, causing pressure to rise and potentially leading to an explosion, the battery explosion-proof plate 2 can be ruptured in time, releasing the battery pressure in the containment space through the explosion-proof hole 11, reducing the risk of explosion.

[0057] In this embodiment, the battery cover 1, battery casing, and battery explosion-proof sheet 2 are all made of steel, specifically stainless steel, such as SUS304 or SUS316L. Stainless steel is more corrosion-resistant and can improve the service life of the secondary battery. In other alternative embodiments, the battery cover 1, battery casing, and battery explosion-proof sheet 2 can also be made of non-stainless steel.

[0058] Because steel has a higher structural strength than aluminum, this embodiment uses steel to make the battery cover 1, battery casing, and battery explosion-proof sheet 2. Under the same strength conditions, the wall thickness of the battery cover 1, battery casing, and battery explosion-proof sheet 2 can be reduced compared to those made of traditional aluminum. With the battery casing size remaining unchanged, more space is reserved for the battery cells located inside the casing, increasing the battery's capacity. Furthermore, the steel battery casing is more heat-resistant, can withstand greater pressure, and is less prone to severe burn-through, reducing the risk of heat diffusion from the battery cells.

[0059] In this embodiment, the wall thickness of the battery explosion-proof sheet 2 is 0.1~0.2mm.

[0060] like Figure 1 , Figure 2 , Figures 4-6 As shown, the battery explosion-proof sheet 2 in this embodiment is an integral structure. The battery explosion-proof sheet 2 includes a first flat part 3 and a protruding part 4. The first flat part 3 is disposed on the outer periphery of the protruding part 4.

[0061] like Figure 6 As shown, the first planar portion 3 is provided with a welding area 5, which is used for welding to the battery cover plate 1. Specifically, in this embodiment, the welding area 5 is formed at the outer peripheral end of the first planar portion 3, and the welding area 5 and the battery cover plate 1 are connected by welding processes such as laser penetration welding.

[0062] like Figure 1 and Figure 2 As shown, the first planar portion 3 has first end faces 31 spaced apart in the thickness direction of the battery explosion-proof sheet 2. Figure 6 The upper end face of the first planar part 3) and the second end face 32 ( Figure 6 The protrusion 4 is formed recessed from the first end face 31 toward the second end face 32 along the thickness direction of the battery explosion-proof sheet 2. The protrusion 4 has a groove 41 with an opening toward the first end face 31. The end of the protrusion 4 away from the first end face 31 in the thickness direction of the battery explosion-proof sheet 2 protrudes beyond the second end face 32, so that the first flat part 3 and the protrusion 4 are misaligned in the thickness direction of the battery explosion-proof sheet 2.

[0063] like Figure 3 and Figure 4 As shown, in this embodiment, the portion of the battery explosion-proof sheet 2 located on the inner periphery of the first flat portion 3 is a protrusion 4, that is, the portion of the battery explosion-proof sheet 2 on the inner periphery side of the first flat portion 3 all protrude from the first end face 31 toward the second end face 32 along the thickness direction of the battery explosion-proof sheet 2.

[0064] like Figure 1 and Figure 2As shown, during the assembly of the secondary battery, the protrusion 4 in this embodiment faces the interior of the secondary battery and extends into the interior of the explosion-proof hole 11, thereby preventing the protrusion 4 from being exposed outside the battery cover plate 1. This makes the protrusion 4 less likely to interfere with other structures, facilitating the assembly of the secondary battery. Furthermore, the fit between the outer peripheral wall of the protrusion 4 and the hole wall of the explosion-proof hole 11 enables rapid positioning of the battery explosion-proof plate 2 and the battery cover plate 1, improving the assembly efficiency of the secondary battery.

[0065] In other alternative embodiments, the protrusion 4 may also face outwards from the secondary battery, i.e., the protrusion 4 does not extend into the explosion-proof hole 11.

[0066] like Figure 6 As shown, in this embodiment, the first planar portion 3 and the protruding portion 4 are directly processed from the same sheet of material with uniform thickness. Therefore, the thickness of the battery explosion-proof sheet 2 is the wall thickness d1 of the first planar portion 3 and the wall thickness d2 of the protruding portion 4. That is, the wall thickness d1 of the first planar portion 3 is equal to the wall thickness d2 of the protruding portion 4, both of which are 0.1~0.2mm, so as to facilitate the processing of the battery explosion-proof sheet 2.

[0067] In other alternative embodiments, the wall thickness d1 of the first planar portion 3 and the wall thickness d2 of the protrusion 4 may not be equal. Alternatively, the wall thickness d1 of the first planar portion 3 and the wall thickness d2 of the protrusion 4 may be designed to other values ​​according to actual needs.

[0068] Furthermore, such as Figure 1 and Figure 6 As shown, the protrusion 4 has an explosion-proof groove 6 on one end face of the battery explosion-proof sheet 2 near the first end face 31 in the thickness direction. The explosion-proof groove 6 is an indentation structure provided on the end face of the protrusion 4 to reduce the thickness of the protrusion 4 at the location where the explosion-proof groove 6 is provided. The depth h of the explosion-proof groove 6 in the thickness direction of the battery explosion-proof sheet 2 is less than the wall thickness d2 of the protrusion 4, that is, the explosion-proof groove 6 will not penetrate the protrusion 4. The explosion-proof groove 6 is used to break open in time when the battery pressure in the secondary battery's housing space is too high, quickly release the pressure, and prevent an explosion.

[0069] Specifically, in this embodiment, the depth h of the explosion-proof notch 6 is 0.05~0.12mm to facilitate timely discharge of gas generated by the battery cell. In other alternative embodiments, the depth h of the explosion-proof notch 6 can also be designed to other values ​​according to actual needs.

[0070] In other alternative embodiments, the explosion-proof notch 6 may also be provided on the end face of the protrusion 4 away from the first end face 31 in the thickness direction of the battery explosion-proof sheet 2.

[0071] In this embodiment, the welding area 5 and the explosion-proof groove 6 of the battery explosion-proof sheet 2 are located in different parts of the battery explosion-proof sheet 2. The first flat part 3 with the welding area 5 and the protruding part 4 with the explosion-proof groove 6 are staggered in the thickness direction of the battery explosion-proof sheet 2, which can effectively prevent the heat generated by welding at the welding area 5 from being transferred to the explosion-proof groove 6, prevent the explosion-proof groove 6 from deforming, and prevent the battery explosion-proof sheet 2 from failing.

[0072] Furthermore, such as Figure 6 As shown, the distance d3 between the end face 4 of the protrusion 4 facing the first end face 31 in the thickness direction of the battery explosion-proof sheet 2 and the first end face 31 is 0.2~0.4mm. In this embodiment, by controlling the height difference between the first flat part 3 and the protrusion 4 in the thickness direction of the battery explosion-proof sheet 2 within a certain range, on the one hand, it avoids the heat generated by welding at the welding area 5 from being easily transferred to the explosion-proof groove 6 on the protrusion 4 due to the excessively low height difference, thus preventing deformation of the explosion-proof groove 6 and preventing the battery explosion-proof sheet 2 from failing. On the other hand, it avoids the protrusion 4 from extending excessively into the battery and interfering with the cell due to the excessively high height difference, thus ensuring the reliability of the secondary battery; or it avoids the protrusion 4 from protruding excessively from the outside of the battery and occupying too much space due to the excessively high height difference, thereby making the structure of the secondary battery more compact.

[0073] In other alternative embodiments, the distance d3 between the end face of the protrusion 4 facing the first end face 31 in the thickness direction of the battery explosion-proof sheet 2 and the first end face 31 can also be designed to other values ​​according to actual needs.

[0074] Furthermore, such as Figure 6 As shown, the shortest distance d4 between the outer peripheral wall of the first flat portion 3 and the outer peripheral wall of the protrusion 4 is greater than or equal to 2 mm. On the one hand, sufficient welding space can be reserved on the first flat portion 3 to ensure the welding strength between the first flat portion 3 and the battery cover plate 1. On the other hand, by increasing the distance between the first flat portion 3 and the protrusion 4, the heat transfer path generated by welding can be extended, gradually consuming the heat generated by welding, so that the temperature is lower closer to the explosion-proof notch 6, further preventing deformation at the explosion-proof notch 6 and preventing the battery explosion-proof sheet 2 from failing.

[0075] Specifically, the shortest distance d4 between the outer peripheral wall of the first planar portion 3 and the outer peripheral wall of the protrusion 4 can be the distance between the outer peripheral wall of the first planar portion 3 and the outer peripheral wall of the protrusion 4 in the width or length direction of the battery explosion-proof sheet 2.

[0076] In other alternative embodiments, the shortest distance d4 between the outer peripheral wall of the first planar portion 3 and the outer peripheral wall of the protrusion 4 can also be designed to other values ​​according to actual needs.

[0077] Furthermore, such as Figure 6 As shown, the shortest distance d5 between the explosion-proof notch 6 and the inner peripheral wall of the protrusion 4 is greater than or equal to 1 mm, providing sufficient machining space for processing the explosion-proof notch 6 and facilitating its processing. Specifically, the shortest distance d5 between the explosion-proof notch 6 and the inner peripheral wall of the protrusion 4 can be the distance between them in the width or length direction of the battery explosion-proof sheet 2.

[0078] In other alternative embodiments, the battery explosion-proof plate 2 described above can also be installed on the battery housing, that is, the explosion-proof hole 11 is opened on the battery housing, the battery explosion-proof plate 2 covers the explosion-proof hole 11 on the battery housing, and the welding area 5 of the battery explosion-proof plate 2 is welded to the battery housing.

[0079] Example 2

[0080] The structure of the secondary battery and the battery explosion-proof sheet 2 in this embodiment is basically the same as that in embodiment 1, except that:

[0081] like Figures 7-9 As shown, the battery explosion-proof sheet 2 includes a first planar portion 3, a protruding portion 4, and a second planar portion 7. The protruding portion 4 is disposed on the inner periphery of the first planar portion 3, and the second planar portion 7 is disposed on the inner periphery of the protruding portion 4. The second planar portion 7 has a third end face 71 and a fourth end face 72 spaced apart in the thickness direction of the battery explosion-proof sheet 2. In this embodiment, the first end face 31 of the first planar portion 3 and the third end face 71 of the second planar portion 7 are flush, and the second end face 32 of the first planar portion 3 and the fourth end face 72 of the second planar portion 7 are flush. The protruding portion 4 protrudes from the third end face 71 along the thickness direction of the battery explosion-proof sheet 2 toward the fourth end face 72 and extends beyond the fourth end face 72, so that the protruding portion 4 and the first planar portion 3 and the second planar portion 7 are staggered in the thickness direction of the battery explosion-proof sheet 2.

[0082] In this embodiment, the protrusion 4 is formed only around the area with the explosion-proof notch 6. The structural design of the battery explosion-proof sheet 2 is more flexible and has a wider range of applications.

[0083] In other alternative embodiments, the two end faces of the first flat portion 3 and the second flat portion 7 in the thickness direction of the battery explosion-proof sheet 2 may not need to be aligned accordingly.

[0084] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship of the device or component shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or component 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 this utility model.

[0085] While specific embodiments of this utility model have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this utility model is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this utility model, but all such changes and modifications fall within the scope of protection of this utility model.

Claims

1. A battery explosion-proof sheet, characterized in that, The battery explosion-proof sheet is made of steel. The battery explosion-proof sheet includes a first flat portion and a protruding portion. The first flat portion is disposed on the outer periphery of the protruding portion. The first flat portion has a first end face and a second end face that are spaced apart in the thickness direction of the battery explosion-proof sheet. The protruding portion is recessed from the first end face along the thickness direction of the battery explosion-proof sheet toward the second end face. The end of the protruding portion away from the first end face in the thickness direction of the battery explosion-proof sheet protrudes along the thickness direction of the battery explosion-proof sheet to extend beyond the second end face. The first planar portion is provided with a welding area, which is used for welding to the battery cover or battery casing; The protrusion has an explosion-proof groove on one end face in the thickness direction of the battery explosion-proof sheet, and the depth of the explosion-proof groove is less than the wall thickness of the protrusion.

2. The battery explosion-proof sheet as described in claim 1, characterized in that, The wall thickness d1 of the first planar portion is 0.1~0.2mm; and / or the wall thickness d2 of the protrusion is 0.1~0.2mm.

3. The battery explosion-proof sheet as described in claim 2, characterized in that, The wall thickness d1 of the first planar portion is equal to the wall thickness d2 of the protrusion.

4. The battery explosion-proof sheet as described in claim 2, characterized in that, When the wall thickness d2 of the protrusion is 0.1~0.2mm, the depth h of the explosion-proof groove is 0.05~0.12mm.

5. The battery explosion-proof sheet as described in claim 1, characterized in that, The distance d3 between the end face of the protrusion facing the first end face in the thickness direction of the battery explosion-proof sheet and the first end face is 0.2~0.4mm.

6. The battery explosion-proof sheet as described in claim 1, characterized in that, The welding area is located at the outer peripheral end of the first planar portion, and the shortest distance d4 between the outer peripheral wall of the first planar portion and the outer peripheral wall of the protrusion is greater than or equal to 2 mm.

7. The battery explosion-proof sheet as described in claim 1, characterized in that, The battery explosion-proof sheet further includes a second planar portion, which is disposed on the inner periphery of the protrusion. The second planar portion has a third end face and a fourth end face that are spaced apart in the thickness direction of the battery explosion-proof sheet. The protrusion extends from the third end face toward the fourth end face along the thickness direction of the battery explosion-proof sheet and extends beyond the fourth end face.

8. The battery explosion-proof sheet as described in any one of claims 1-7, characterized in that, The shortest distance d5 between the explosion-proof groove and the inner peripheral wall of the protrusion is greater than or equal to 1 mm.

9. A secondary battery, characterized in that, The secondary battery includes a battery cover, a battery housing, and a battery explosion-proof sheet as described in any one of claims 1-8. The battery explosion-proof sheet is fixed to the battery cover or the battery housing and covers the explosion-proof holes on the battery cover or the battery housing.

10. The secondary battery as described in claim 9, characterized in that, The protrusion faces the interior of the secondary battery and extends into the interior of the explosion-proof hole.

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