Cylindrical battery monomer and battery module

Abstract

The utility model relates to the technical field of batteries, in particular to a cylindrical battery monomer, and aims to solve the technical problems that when the cylindrical battery monomer is in thermal runaway under different working conditions, a roll core is sprayed out to generate adverse effects, and the safety performance is poor due to a smaller valve opening area. Therefore, the cylindrical single battery provided by the utility model comprises a shell with an opening at one end; the electrode assembly is arranged in the shell; the first plate body is arranged at the opening, the first plate body is electrically connected with the shell and the electrode assembly, and the first plate body is provided with a first weak part; and the second plate body is arranged on one side, far away from the electrode assembly, of the first plate body, is hermetically connected with the first plate body and is provided with a second weak part. According to the utility model, the welding process of the first plate body and the second plate body with the shell is simplified, the part and assembly cost is reduced, and the production and manufacturing efficiency is improved; and meanwhile, the safety requirements of the battery cell under different working conditions are met, enough pressure relief area can be ensured, and the safety of the battery cell is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and specifically provides a cylindrical battery monomer and a battery module. Background Art

[0002] Lithium-ion batteries have outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide adaptability, and small self-discharge coefficient. They are one of the most widely used batteries in the world today and an important part of the development of new energy.

[0003] With the continuous upgrading of market demand, cylindrical batteries have developed from 18650 and 21700 to the larger and more energy-dense 4680 series cylindrical batteries. Compared with 18650 and 21700 cylindrical cells, the 4680 cylindrical battery adopts a full-ear design, which effectively shortens the current path, promotes smoother movement of electrons inside the battery, reduces the internal resistance of the cell itself, and significantly reduces Joule heat loss. In addition, cylindrical batteries are made of stainless steel, have higher mechanical strength, and can effectively absorb the pressure caused by the expansion of the negative electrode, so they are more suitable for high-silicon and high-nickel systems.

[0004] In the prior art, in order to avoid thermal runaway inside large cylindrical batteries, an explosion-proof valve is generally installed at the end of the battery cell, for example, on the negative electrode cover. When the gas production inside the battery causes the pressure to increase, the explosion-proof valve on the electrode terminal or the negative electrode cover explodes, and the gas inside the battery is released or discharged in time to prevent the battery from further explosion. However, when the battery is slowly producing gas, after the explosion-proof valve on the negative electrode cover explodes, the winding core inside the battery will erupt, and the erupted pole piece may contact with other components and produce adverse effects; in addition, when the battery is violently producing gas, the explosion-proof valve of the negative electrode cover cannot guarantee sufficient valve opening area, and rapid gas production causes the battery to explode, which has poor safety. Therefore, it is urgent to develop a battery structure that can take into account different working conditions at the same time. Utility Model Content

[0005] The utility model aims to solve the above technical problem, that is, to solve the technical problem of poor safety performance caused by the adverse effects of core ejection and small valve opening area when a cylindrical battery cell is thermally runaway under different working conditions.

[0006] In a first aspect, the utility model provides a cylindrical battery cell, comprising: a shell having an opening at one end; an electrode assembly disposed in the shell; a first plate body disposed at the opening, the first plate body being electrically connected to the shell body and the electrode assembly respectively, and the first plate body being provided with a first weak portion; a second plate body being disposed on a side of the first plate body away from the electrode assembly and being sealed and connected to the first plate body, and the second plate body being provided with a second weak portion.

[0007] In the above technical scheme, by electrically connecting the first plate body to the shell and the electrode assembly respectively, and the second plate body is sealed and connected to the first plate body, the welding process of the first plate body, the second plate body and the shell is simplified, the cost of parts and assembly is reduced, and the efficiency of production and manufacturing is improved; at the same time, the first weak part and the second weak part are respectively provided on the first plate body and the second plate body, which can meet the safety requirements of the battery cell under different working conditions. When the battery cell produces gas slowly, the first weak part on the first plate body can support the electrode assembly to avoid secondary thermal runaway, and the second weak part can explode to release pressure in time to ensure the safety of the battery; when the battery cell is severely damaged and produces gas violently, the first weak part on the first plate body and the second weak part on the second plate body are both opened, and the exhaust space is sufficient, which can ensure sufficient pressure relief area to ensure the safety of the battery cell.

[0008] In some embodiments, a projection of the second weak portion on the first plate is located outside the first weak portion.

[0009] In some embodiments, the outer shape of the first weak portion and / or the outer shape of the second weak portion is circular or arc-shaped.

[0010] In some embodiments, the first weak portion and the second weak portion are both circular in shape, and the diameter of the second weak portion is greater than the diameter of the first weak portion.

[0011] In the above technical solution, if the diameter of the second weak portion is smaller than the diameter of the first weak portion, the second weak portion will hinder the bursting of the first weak portion.

[0012] In some embodiments, the diameter of the first weak portion is greater than or equal to 15 mm and less than or equal to 27 mm, and the diameter of the second weak portion is greater than or equal to 20 mm and less than or equal to 37 mm.

[0013] In the above technical solution, if the diameter of the first weak part is set too small, the valve opening area does not meet the requirements and it is difficult to burst open in time; if it is set too large, it will affect the welding area with the pole ear; if the diameter of the second weak part is set too small, it will affect the bursting of the first weak part; if it is set too large, it will not meet the component design requirements.

[0014] In some embodiments, the first weak portion is a notch on the surface of the first plate; and / or the second weak portion is a notch on the surface of the second plate.

[0015] In some embodiments, the first plate body includes a first connecting portion and a second connecting portion, the first connecting portion is electrically connected to the second plate body and the electrode assembly respectively, the second connecting portion is electrically connected to the shell, and the first weak portion is arranged on the surface of the first connecting portion.

[0016] In some embodiments, the second plate body includes a second plate body and a convex portion surrounding the second plate body, the convex portion protrudes from an inner surface of the second plate body facing the electrode assembly, and the second weak portion is disposed on a surface of the second plate body.

[0017] In the above technical solution, the convex portion is arranged to protrude from the inner surface of the second plate body, which can enhance the overall strength of the second plate body.

[0018] In some embodiments, the thickness of the first plate is greater than or equal to 0.3 mm and less than or equal to 0.65 mm, and / or the thickness of the second plate is greater than or equal to 0.2 mm and less than or equal to 0.65 mm.

[0019] In the above technical solution, if the thickness of the first plate is set too thin, it will be detrimental to the welding of the first plate and the shell, and if it is set too thick, it will lead to poor welding with the pole ear; if the thickness of the second plate is set too thin, it will affect the deformation and thus affect the valve opening area, and if it is set too thick, it will increase the cost.

[0020] In some embodiments, the material of the first plate is the same as that of the shell, and / or the material of the first plate is the same as that of the second plate.

[0021] In the above technical solution, the material of the first plate and the shell is set to be the same; and / or the material of the first plate and the second plate is set to be the same, which can reduce the difficulty of welding between the first plate, the second plate and the shell and enhance the overall strength.

[0022] In some embodiments, the shell, the first plate and the second plate are all made of low carbon steel.

[0023] In the above technical solution, the shell, the first plate and the second plate are made of low-carbon steel, which reduces the internal resistance of the battery cell structure.

[0024] In some embodiments, the first plate body and the second plate body are fixed by welding; and / or, the first plate body and the second plate body are fixed by bonding.

[0025] In the above technical solution, the first plate body and the second plate body are fixed by welding or bonding, which can simplify the process and reduce the difficulty of production.

[0026] In a second aspect, the utility model further provides a battery module, wherein the battery module comprises a plurality of the above-mentioned cylindrical battery cells.

[0027] The advantages of the battery module and the cylindrical battery cell described above over the prior art are the same, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 is a cross-sectional view of a cylindrical battery cell provided by an embodiment of the utility model;

[0030] Figure 2 It is a partial cross-sectional view of a cylindrical battery cell provided by an embodiment of the utility model;

[0031] Figure 3 yes Figure 2 A schematic diagram of the structure with a partial enlargement at the center;

[0032] Figure 4 yes Figure 2 A partial exploded view of the .

[0033] List of reference numerals:

[0034] 1. Shell; 11. Side wall; 111. Inner wall surface; 112. Outer end surface; 113. Outer wall surface; 2. Electrode assembly; 3. First plate body; 31. First connecting portion; 311. First vertical portion; 3111. Peripheral surface; 312. Extension portion; 3121. Inner surface; 3122. First end surface; 3123. Second outer surface; 32. Second connecting portion; 4. Second plate body; 41. Second plate body; 42. Protrusion; 421. Second vertical portion; 4211. Peripheral surface; 4212. Second end surface; 422. Horizontal portion; 4221. First outer surface; 5. First weak portion; 6. Second weak portion. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0036] It should be noted that in the description of the present invention, the terms "inside", "outside", "top", "bottom" and other terms indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", and "fourth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0037] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "setting" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0039] Please refer to Figures 1 to 4 , Figures 1 to 4 A schematic diagram of the structure of a cylindrical battery cell provided in an embodiment of the utility model.

[0040] like Figures 1 to 4 As shown, the cylindrical battery cell of the embodiment of the present application includes: a shell 1, one end of which has an opening. In this embodiment, the shell 1 is a hollow structure with an opening on one side, which is used to accommodate the electrode assembly 2 and the electrolyte. The electrode assembly 2 is arranged in the accommodating cavity of the shell 1. The shell 1 includes a side wall 11 and a top wall (not shown in the figure) connected to the side wall 11. The top wall is used to be arranged on components such as electrode terminals. The shape of the shell 1 can be determined according to the specific shape of the electrode assembly 2. In this embodiment, the electrode assembly 2 is a cylindrical structure, and the shell 1 is selected as a cylindrical shell 1. The shell 1 can be positively charged, negatively charged, or uncharged. The first plate 3 is arranged at the opening of the shell 1, and the first plate 3 is electrically connected to the shell 1 and the electrode assembly 2 respectively. In this embodiment, the shell 1 is directly connected to the electrode assembly 2, and the shell 1 is charged. Optionally, the first plate 3 and the shell 1 can be connected by welding, so that the first plate 3 and the shell 1 can have substantially the same potential. The second plate body 4 is arranged on a side of the first plate body 3 away from the electrode assembly 2, and the first plate body 3 and the second plate body 4 are electrically connected. In the present embodiment, the second plate body 4 is electrically connected to the first plate body 3 but not directly to the shell 1, which simplifies the welding process of the first plate body 3, the second plate body 4 and the shell 1, improves production efficiency and reduces manufacturing costs.

[0041] In this embodiment, the second plate body 4 is arranged on the side of the first plate body 3 away from the electrode assembly 2, the first plate body 3 and the second plate body 4 are arranged oppositely, the first plate body 3 is provided with a first weak portion 5, and the second plate body 4 is provided with a second weak portion 6. The first plate body 3 and the second plate body 4 are both provided with weak portions, compared with the solution of providing an explosion-proof valve on the cover plate in the prior art, the safety requirements of the battery cell under different working conditions can be met. When the battery cell produces gas slowly, the first weak portion 5 on the first plate body 3 can support the electrode assembly 2 to avoid secondary thermal runaway; and when the battery cell is severely damaged and produces gas violently, the first weak portion 5 on the first plate body 3 and the second weak portion 6 on the second plate body 4 are both opened, which can ensure sufficient pressure relief area and ensure the safety of the battery cell. In some embodiments, the projection of the second weak portion 6 on the first plate 3 is located outside the first weak portion 5. Since the first plate 3 and the second plate 4 are arranged relative to each other, the area formed by the second weak portion 6 on the second plate 4 is outside the area formed by the first weak portion 5 on the first plate 3. The valve opening area of ​​the second weak portion 6 is larger than the valve opening area of ​​the first weak portion 5. In this way, under the same internal pressure of the battery cell, the first weak portion 5 and the second weak portion 6 have different bursting timings. Therefore, the safety requirements of the battery under different working conditions can be met and the safety of the battery cell can be guaranteed. Further, in this embodiment, the shape of the first weak portion 5 can be circular or arc-shaped. In this case, the shape of the second weak portion 6 can be circular or arc-shaped, or other shapes; or, the shape of the second weak portion 6 is circular or arc-shaped. In this case, the shape of the first weak portion 5 can be circular or arc-shaped, or other shapes. The shapes of the first weak portion 5 and the second weak portion 6 can meet the safety requirements, and the utility model is not limited here. Preferably, the shapes of the first weak portion 5 and the second weak portion 6 are both circular. Further, the diameter of the second weak portion 6 is greater than the diameter of the first weak portion 5, that is, the circular area of ​​the second weak portion 6 is greater than the circular area of ​​the first weak portion 5, that is, the valve opening area of ​​the second weak portion 6 is greater than the valve opening area of ​​the first weak portion 5. In some embodiments, the diameter of the first weak portion 5 is greater than or equal to 15 mm and less than or equal to 27 mm, and the diameter of the first weak portion 5 can be 15 mm, 16 mm, 17 mm, 18 mm...26 mm or 27 mm, as long as the safety requirements can be met, the diameter of the second weak portion 6 is greater than or equal to 20 mm and less than or equal to 37 mm, and the diameter of the second weak portion 6 can be 20 mm, 21 mm, 22 mm, 23 mm...36 mm or 37 mm, as long as the diameter of the second weak portion 6 is greater than the diameter of the first weak portion 5 and the safety requirements can be met. Preferably, the diameter of the first weak portion 5 is 20 mm, and the diameter of the second weak portion 6 is 28 mm. Furthermore, in the present embodiment, the first weak portion 5 is a notch formed by punching on the surface of the first plate body 3 , and the second weak portion 6 is a notch formed by punching on the surface of the second plate body 4 .

[0042] In this embodiment, the first plate body 3 includes a first connection portion 31 and a second connection portion 32, and the second connection portion 32 is a circular plate body, which forms inner and outer surfaces that are arranged oppositely and parallel to each other in the thickness direction, and the inner surface of the second connection portion 32 is electrically connected to the electrode assembly 2, and the outer surface of the second connection portion 32 is electrically connected to the second plate body 4. Optionally, the second connection portion 32 is connected to the electrode assembly 2 and the second plate body 4 respectively by laser welding, or other connection methods can be used to ensure the effect of tight connection and good sealing performance, and this embodiment is not limited here. Further, the first connection portion 31 is arranged around the outer periphery of the second connection portion 32, and the first connection portion 31 is electrically connected to the shell 1. Optionally, the first connection portion 31 is connected to the shell 1 by laser welding, or other connection methods can be used to ensure the effect of tight connection and good sealing performance, and this embodiment is not limited here. Further, the second weak portion 6 is provided at the first connection portion 31.

[0043] In this embodiment, the first connection portion 31 includes a first vertical portion 311 and an extension portion 312. The first vertical portion 311 is extended along the center line direction of the cylindrical battery. One end of the first vertical portion 311 is connected to the second connection portion 32, and the other end is connected to the extension portion 312. In some embodiments, the side of the first vertical portion 311 away from the center of the cylindrical battery is a first outer peripheral surface 3111, and there is a gap between the first outer peripheral surface 3111 of the first vertical portion 311 and the inner wall surface 111 of the side wall 11 of the shell 1. The extension portion 312 is arranged in a direction perpendicular to the first vertical portion 311 and surrounds the first outer peripheral surface 3111 of the first vertical portion 311. The extension portion 312 is electrically connected to the shell 1. Optionally, the second connection portion 32 is connected to the electrode assembly 2 and the second plate body 4 respectively by laser welding, and other connection methods can also be used to ensure a tight connection and good sealing performance. In some embodiments, the side of the side wall 11 of the shell 1 surrounding the opening is the outer end face 112, and the side of the extension 312 facing the side wall 11 is the inner surface 3121. The inner surface 3121 of the extension 312 is welded to the outer end face 112, so that the shell 1 and the first plate 3 are connected as a whole. Optionally, the first connecting portion 31 and the shell 1 are connected by laser welding, or other connection methods can be used to ensure a tight connection and good sealing performance. Specifically, the laser is irradiated along the inner surface 3121 of the extension 312 and the outer end face 112 of the side wall 11, and the laser radiation heats the surface to be processed. The surface heat diffuses to the inside through heat conduction, so that the surface of the workpiece melts and forms a specific molten pool, and then the extension 312 and the side wall 11 of the shell 1 are welded as a whole. In some embodiments, the side of the extension portion facing away from the center of the first plate body 3 is a first end face 3122, and the maximum distance between the first end face 3122 of the extension portion 312 and the outer wall surface 113 of the side wall 11 is less than or equal to 0.15 mm, and can be 0 mm, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm or 0.15 mm.

[0044] In this embodiment, the second plate body 4 includes a second plate body 41 and a convex portion 42 surrounding the second plate body 41, and the convex portion 42 protrudes from the inner surface of the second plate body 41 facing the electrode assembly 2. The second plate body 41 is a circular plate-shaped structure, and the convex portion 42 is an annular structure surrounding the outer side of the second plate body 41. The convex portion 42 is processed on the second plate body 4 and protrudes relative to the second plate body 4 facing the electrode assembly 2. Further, the second weak portion 6 is provided on the second plate body 41. In some embodiments, the first plate body 3 and the second plate body 4 are interference fit, that is, the convex portion 42 and the second plate body 4 are interference fit. The convex portion 42 includes a second vertical portion 421 and a horizontal portion 422, the second outer peripheral surface 4211 of the second vertical portion 421 abuts against the inner peripheral surface of the first vertical portion 311, and the horizontal portion 422 abuts against the second connecting portion 32. The interference fit can increase the connection strength between the first plate body 3 and the second plate body 4 and improve the sealing performance. At the same time, the first plate body 3 and the second plate body 4 are interference fit, and no external equipment is required to fix the first and second plate bodies 4, which simplifies the assembly process. Optionally, the second outer peripheral surface 4211 of the second vertical portion 421 and the inner peripheral surface of the first vertical portion 311 are connected by laser welding. During welding, the laser is irradiated on the connection, and the laser partially melts and connects them together to achieve sealing and reduce the risk of electrolyte leakage from the connection. In some embodiments, the side of the horizontal portion 422 facing away from the electrode assembly 2 is the first outer surface 4221, and the side of the extension portion 312 facing away from the electrode assembly 2 is the second outer surface 3123. The distance from the first outer surface 4221 of the horizontal portion 422 to the electrode assembly 2 is less than the distance from the second outer surface 3123 of the extension portion 312 to the electrode assembly 2. In other embodiments, a side of the second vertical portion 421 facing away from the electrode assembly 2 is a second end surface 4212 , and a distance from the second end surface 4212 of the second vertical portion 421 to the electrode assembly 2 is smaller than a distance from the second outer surface 3123 of the extension portion 312 to the electrode assembly 2 .

[0045] In the present embodiment, the thickness of the first plate body 3 is greater than or equal to 0.3 mm and less than or equal to 0.65 mm. Optionally, the thickness of the first plate body 3 is 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm or 0.65 mm. The thickness of the first plate body 3 is selected to ensure the connection strength of the first plate body 3 and not affect the welding effect and the flow rate. This embodiment is not limited here. In some embodiments, the thickness of the second plate body 4 is greater than or equal to 0.2 mm and less than or equal to 0.65 mm. Optionally, the thickness of the second plate body 4 is 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm and 0.65 mm. The thickness of the second plate body 4 is selected to ensure the connection strength of the second plate body 4 and not affect the welding effect and the flow rate. This embodiment is not limited here.

[0046] In this embodiment, the first plate 3 is made of the same material as the shell 1, which can ensure the connection strength with the shell 1, and the first plate 3 can also provide good support for the electrode assembly 2. Optionally, the shell 1 is made of low-carbon steel, the first plate 3 is low-carbon steel, and the second plate 4 is stainless steel. In some embodiments, the second plate 4 is made of the same material as the first plate 3 to ensure the connection strength of the first plate 3 and the second plate 4. Optionally, the shell 1 is made of low-carbon steel, and the first plate 3 and the second plate 4 are made of stainless steel. Further, the shell 1, the first plate 3 and the second plate 4 are made of the same material. Preferably, the shell 1, the first plate 3 and the second plate 4 are made of low-carbon steel or stainless steel.

[0047] In this embodiment, the first plate 3 and the second plate 4 are fixed by welding. Optionally, the first plate 3 and the second plate 4 are fixed by laser welding, or other connection methods can be used to ensure the effect of tight connection and good sealing performance. In some embodiments, the first plate 3 and the second plate 4 are fixed by bonding. Optionally, the first plate 3 and the second plate 4 are fixed by structural adhesive, or other connection methods can be used to ensure the effect of tight connection and good sealing performance, which is not limited in this embodiment. The utility model also provides a battery module with multiple cylindrical battery cells. The beneficial effects of the battery module are the same as the advantages of the cylindrical battery cells in this embodiment over the prior art, which will not be repeated here.

[0048] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A cylindrical battery cell, characterized in that: include: A housing having an opening at one end; An electrode assembly is disposed in the housing; A first plate body, disposed at the opening, the first plate body being electrically connected to the housing and the electrode assembly respectively, and the first plate body being provided with a first weak portion; The second plate body is arranged on a side of the first plate body away from the electrode assembly and is sealed and connected to the first plate body. The second plate body is provided with a second weak portion.

2. The cylindrical battery cell according to claim 1, characterized in that: The projection of the second weak portion on the first plate is located outside the first weak portion.

3. The cylindrical battery cell according to claim 1, characterized in that: The outer shape of the first weak portion and / or the outer shape of the second weak portion is circular or arc-shaped.

4. The cylindrical battery cell according to claim 3, characterized in that: The first weak portion and the second weak portion are both circular in shape, and the diameter of the second weak portion is greater than the diameter of the first weak portion.

5. The cylindrical battery cell according to claim 4, characterized in that: The diameter of the first weak portion is greater than or equal to 15 mm and less than or equal to 27 mm, and the diameter of the second weak portion is greater than or equal to 20 mm and less than or equal to 37 mm.

6. The cylindrical battery cell according to claim 1, characterized in that: The first weak portion is a notch on the surface of the first plate; and / or the second weak portion is a notch on the surface of the second plate.

7. The cylindrical battery cell according to claim 1, characterized in that: The first plate body includes a first connecting portion and a second connecting portion, the first connecting portion is electrically connected to the second plate body and the electrode assembly respectively, the second connecting portion is electrically connected to the shell, and the first weak portion is arranged on the surface of the first connecting portion.

8. The cylindrical battery cell according to claim 7, characterized in that: The second plate body includes a second plate body and a convex portion surrounding the second plate body, the convex portion protrudes from the inner surface of the second plate body facing the electrode assembly, and the second weak portion is arranged on the surface of the second plate body.

9. The cylindrical battery cell according to claim 1, characterized in that: The thickness of the first plate body is greater than or equal to 0.3 mm and less than or equal to 0.65 mm, and / or the thickness of the second plate body is greater than or equal to 0.2 mm and less than or equal to 0.65 mm.

10. The cylindrical battery cell according to claim 1, characterized in that: The material of the first plate is the same as that of the shell, and / or the material of the first plate is the same as that of the second plate.

11. The cylindrical battery cell according to claim 1, characterized in that: The shell, the first plate and the second plate are all made of low-carbon steel.

12. The cylindrical battery cell according to claim 1, characterized in that: The first plate body and the second plate body are fixed by welding, and / or the first plate body and the second plate body are fixed by bonding.

13. A battery module, characterized in that: A cylindrical battery cell comprising any one of claims 1 to 12.

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