Cylindrical secondary battery

Abstract

The utility model belongs to the technical field of batteries, and particularly relates to a cylindrical secondary battery. The battery comprises: a case in which a battery is placed; the top cover is suitable for covering the opening of the shell; the safety disc is arranged on the side, facing the shell, of the top cover in an attached mode. Wherein the edge of the safety disc is provided with a warped edge, and the warped edge wraps the outer wall of the top cover. The warped edge is arranged on the safety disc, so that after the battery shell is impacted, the safety disc can be kept in a state of covering the top cover, and the sealing performance and the safety performance of the battery are improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to battery technical field, concretely relates to a cylindrical secondary battery. BACKGROUND

[0002] The existing cylindrical secondary battery top will set up the cover body, to realize the sealing of the battery shell.

[0003] However, the traditional cylindrical secondary battery cover body is generally thin, for high specific energy cylindrical secondary battery, after being impacted by external force, deformation is easy to occur, leading to sealing damage, and the battery is prone to thermal runaway and explosion. Therefore, it is urgent to design a cylindrical secondary battery to solve the technical problem of sealing damage after the cover body is impacted and deformed.

[0004] It should be noted that the above information disclosed in the background section is only used to understand the background of the present application, and therefore, it can contain information that does not constitute prior art. INVENTION CONTENTS

[0005] The present application provides at least a cylindrical secondary battery, especially a high specific energy cylindrical secondary battery, which can be a lithium ion battery, a sodium ion battery or a potassium ion battery.

[0006] In a first aspect, the present application provides a cylindrical secondary battery, comprising: a shell suitable for placing a battery inside;

[0007] A top cover suitable for covering the opening of the shell; wherein

[0008] A safety sheet is attached to the side of the top cover facing the shell; wherein the edge of the safety sheet has a curled edge covering the outer wall of the top cover.

[0009] The cylindrical secondary battery has a capacity of 3-10 Ah, a battery top cover diameter of 17-27 mm, and a battery height of 60-75 mm.

[0010] In an alternative embodiment, the top cover further comprises an inner rubber ring attached to the side of the safety sheet facing the shell; a bottom cover plate attached to the side of the safety sheet and the inner rubber ring facing the shell; wherein the whole before the shell is sealed is not a standard cylinder, but a trumpet mouth, which is wide at the top and narrow at the bottom.

[0011] In an alternative embodiment, the material of the shell is cold rolled steel sheet spcc.

[0012] In an alternative embodiment, the thickness of the bottom of the shell is slightly thicker than that of the battery shell wall, and the thickness ratio is 1.5:1 to 2.1:1.

[0013] In an alternative embodiment, the shell is provided with a U-shaped groove, and the ratio of the thickness of the wall above the U-shaped groove to the thickness of the wall below the U-shaped groove is 1.1:1 to 1.25:1.

[0014] In an alternative embodiment, the upturned edge is a semi-enclosed structure, and the connection between the upturned edge and the top cover has at least one welding mark.

[0015] In an alternative embodiment, the height of the upturned edge is 50% to 70% of the thickness of the top cover.

[0016] In addition, the upturned edge and the edge of the top cover have a gap.

[0017] In an alternative embodiment, the upturned edge is a fully enclosed structure, and the length of the upturned edge is 1.5 to 2.0 mm.

[0018] In an alternative embodiment, the security sheet has a first protruding portion, a second protruding portion, and a third platform portion arranged in a stepped manner.

[0019] The first protruding portion and the second protruding portion protrude towards the inside of the shell relative to the third platform portion.

[0020] The thickness of the second protruding portion is less than the thickness of the first protruding portion and the third platform portion.

[0021] In an alternative embodiment, the height difference between the second protruding portion and the third platform portion is 0.4 to 0.6 mm.

[0022] In an alternative embodiment, the surface of the second protruding portion has an anti-explosion notch, and the depth of the anti-explosion notch is 20% to 35% of the thickness of the second protruding portion.

[0023] The anti-explosion notch is distributed in the circumferential direction.

[0024] In an alternative embodiment, the surface of the security sheet further has at least one score line.

[0025] The opening direction of the score line is away from the direction of the top cover.

[0026] The depth of the score line is 0.05 to 0.2 mm.

[0027] In an alternative embodiment, the score line is in a straight line shape, and the length of the score line is 4 to 8 mm.

[0028] In an alternative embodiment, the score line is in a circumferential shape, and the angle of the score line is 300° to 330°.

[0029] The thickness of the bottom of the shell is greater than the thickness of the side wall of the shell, and the thickness ratio is 1.5:1 to 2.1:1.

[0030] In an alternative embodiment, the shell is provided with a U-shaped groove, and the ratio of the wall thickness above the U-shaped groove to the wall thickness below the U-shaped groove is 1.1:1 to 1.25:1.

[0031] In an alternative embodiment, the shell material is a cold-rolled steel sheet spcc.

[0032] In an alternative embodiment, the cylindrical secondary battery includes a bottom cover plate, the bottom cover plate is connected to the safety sheet through welding, and the bottom cover plate contains a notch.

[0033] The beneficial effects of the present application are:

[0034] 1. The present application sets a raised edge on the safety sheet, so that the battery shell and the safety sheet can maintain the state of covering the top cover after being impacted, thereby improving the sealing performance of the battery.

[0035] 2. The thickness of the shell bottom is thicker than the side wall, which can withstand greater vertical pressure. The thicker bottom can better disperse the pressure of the internal roll core, structural parts, etc. The cylindrical secondary battery generates a large amount of gas during the charging and discharging process. The thickened bottom can prevent the battery from bulging. Under a large pressure, the battery will not appear concave, thereby ensuring the normal work of the battery internal cell and avoiding safety problems such as battery short circuit.

[0036] 3. The thickened upper wall of the shell U-shaped groove ensures the strength of the battery after processing. During the charging and discharging chemical reaction process in the battery, gas may be generated due to the decomposition of electrolyte at the end of charging of the lithium ion battery. The thicker upper wall can better withstand the internal pressure caused by these gases.

[0037] 4. The shell cold-rolled steel sheet spcc material has excellent cold forming performance. Its yield strength and elongation performance indicators allow it to deform according to the designed shape when subjected to the pressure of the stamping die, without defects such as cracking. During the assembly process of the cylindrical secondary battery, plastic processing procedures such as rolling groove and sealing will be performed. Good forming capability allows the battery to maintain a certain strength while ensuring accurate processing size, reducing the risk of battery shell deformation.

[0038] 5. The bottom cover plate is connected to the safety sheet through welding, and the bottom cover plate contains a notch, which constitutes a cylindrical secondary battery current interrupt device. When the battery is overcharged, the chemical reaction in the battery will become abnormally violent, generating a large amount of gas and causing the internal pressure to rise sharply. The CID can timely cut off the current in this case to prevent the battery from exploding due to overcharging. The existence of the CID can greatly reduce the risk of battery explosion caused by overcharging, prevent the internal pressure of the battery from continuing to rise and cause more serious safety accidents, and cause the battery to explode.

[0039] The utility model discloses the beneficial effect is, the utility model discloses the setting of the edge of the safety sheet is made the battery shell and after being impacted, the safety sheet can keep the state of covering the top cover, thereby improving the sealing performance of battery.

[0040] Other features and advantages of the present application will be set forth in the following description of the drawings, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application. The objects and other advantages of the present application will be realized and attained by the structure particularly pointed out in the description, claims and drawings.

[0041] In order to make the above-mentioned purpose, features and advantages of the utility model more obvious and easy to understand, the following preferred embodiments are specifically described, and the accompanying drawings are shown as follows. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the specific embodiment of the utility model or the technical scheme in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiment or the prior art description, obviously, the drawings in the following description are some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained without creative labor according to these drawings.

[0043] Figure 1 A half package structure schematic diagram of safety sheet provided by the embodiment of the present disclosure is shown in the figure.

[0044] Figure 2 A full package structure schematic diagram of safety sheet provided by the embodiment of the present disclosure is shown in the figure.

[0045] Figure 3 A sectional view of safety sheet provided by the embodiment of the present disclosure is shown in the figure.

[0046] Figure 4 A plan view of safety sheet provided by the embodiment of the present disclosure is shown in the figure.

[0047] In the figure:

[0048] 1, shell; 2, top cover;

[0049] 3, safety sheet; 31, first protruding part; 32, second protruding part; 33, third platform part; 34, anti-explosion notch; 35, line; 36, edge. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme of the utility model will be described clearly and completely below in combination with the drawings. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the utility model.

[0051] It is found through research that the cover is generally thin, and is prone to deformation after being impacted by external force, leading to sealing damage.

[0052] The defects of the above schemes are the results obtained by the inventors after practice and careful research, therefore, the discovery process of the above problems and the solutions proposed by the present disclosure to the above problems should be the contribution of the inventors to the present disclosure in the process of the present disclosure.

[0053] Some embodiments of the present application will be described in detail below in combination with the drawings. In the case of no conflict, the following embodiments and features in the embodiments can be combined with each other. In addition, in the drawings, in order to effectively describe the technical content, the thickness of the components can be exaggerated or reduced.

[0054] It should be noted that: similar reference numbers and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0055] Based on the above research, referring to Figure 1 The present embodiment provides a cylindrical secondary battery, comprising: a shell 1, a top cover 2 and a safety sheet 3, the shell 1 is suitable for placing a battery inside, the top cover 2 is suitable for covering the opening of the shell 1, and the safety sheet 3 is attached to the side of the top cover 2 facing the shell 1. In some embodiments, the diameter of the top cover 2 is 17-27mm, and the height of the shell 1 is 60-75mm. At the same time, the capacity of the cylindrical secondary battery is 3-10Ah, and the cylindrical secondary battery can be a lithium ion battery, a sodium ion battery or a potassium ion battery.

[0056] Further, the edge of the safety sheet 3 has a curled edge 36, and the curled edge 36 covers the outer wall of the top cover 2, so that the curled edge 36 can better fit the edge of the top cover 2. Further, since the curled edge 36 covers the edge of the top cover 2, generally, when the battery is impacted, the stress direction is from the outside to the inside, therefore, the possibility of external impact force damaging the sealing between the top cover 2 and the safety sheet 3 can be greatly reduced.

[0057] Referring to Figure 1In at least one embodiment, the upturned edge 36 is a semi-enclosed structure, i.e., the upturned edge 36 extends to the side wall of the top cover 2. Meanwhile, as an option, a flexible ring is wrapped around the edge of the top cover 2 and the safety sheet 3, so that the top cover 2 and the safety sheet 3 are attached and compressed. The top cover 2 has high hardness and can withstand greater force. The flexible ring can be compressed more, and the top cover 2 is not easy to deform, thereby enhancing the sealing of the battery. The connection between the upturned edge 36 and the top cover 2 has at least one welding mark, thereby further ensuring the stability of the connection between the upturned edge 36 and the top cover 2.

[0058] Referring to Figure 1 In at least one embodiment, the height of the upturned edge 36 is 50%-70% of the thickness of the top cover 2, and the upturned edge 36 has a gap with the edge of the top cover 2, and the size of the gap is 0.03-0.1 mm. Here, it is a glue coating area, which increases the sealing between the whole sheet and the top cover 2.

[0059] Referring to Figure 2 In at least one embodiment, the upturned edge 36 is a fully enclosed structure, and the length of the upturned edge 36 is 1.5-2.0 mm, thereby enhancing the sealing of the battery and preventing incomplete compression of the flexible ring from causing liquid leakage.

[0060] Referring to Figure 3 In at least one embodiment, the safety sheet 3 has a first protruding portion 31, a second protruding portion 32, and a third platform portion 33 arranged in a stepped manner. The first protruding portion (31) and the second protruding portion (32) protrude towards the inside of the shell relative to the third platform portion. The safety sheet 3 is stepped from inside to outside. The thickness of the second protruding portion 32 is less than that of the first protruding portion 31 and the third platform portion 33. The first protruding portion 31 is thicker, and when the safety sheet 3 is laser welded, the laser welds inward, causing the first protruding portion 31 to be welded through. The third platform portion 33 serves as a support and needs a certain strength to prevent bending and breaking during cap assembly.

[0061] Referring to Figure 3 In at least one embodiment, the surface of the second protruding portion 32 has an anti-explosion notch 34, and the depth of the anti-explosion notch 34 is 20%-35% of the thickness of the second protruding portion 32. The anti-explosion notch 34 is distributed in the circumferential direction. Since the second protruding portion 32 is provided with the anti-explosion notch 35, the thickness of the second protruding portion 32 is thinned, thereby facilitating valve opening. The shape of the anti-explosion notch 34 is V-shaped, U-shaped, or trapezoidal, and the ratio of the depth of the anti-explosion notch 35 to the average thickness of the second protruding portion 32 is 20%-35%. In some embodiments, the anti-explosion notch 35 is a circumferential notch 35, the angle of the circumferential notch 35 is 300°-360°, the angle of the V-shaped notch 35 is 20°-60°, the radius of the U-shaped notch 35 is 0.03-0.1 mm, and the ratio of the short side to the long side of the trapezoidal notch 35 is 30%-60%.

[0062] Referring to Figure 3In some embodiments, the height difference between the second protruding part 32 and the third platform part 33 is 0.4-0.6mm, so as to increase the height difference and enhance the strength of the safety sheet 3.

[0063] Referring to Figure 4 In some embodiments, the surface of the safety sheet 3 further has at least one score line 35. The opening direction of the score line 35 is away from the direction of the top cover 2. The depth of the score line 35 is 0.05-0.2mm. As an option, the score line 35 is in a straight line shape, and the length of the score line 35 is 4-8mm. As an option, the score line 35 is in a circumferential shape, and the angle of the score line 35 is 300°-330°.

[0064] Referring to Figure 1 In at least one embodiment, the wall thickness of the shell 1 above the U-shaped groove is greater than the wall thickness below the U-shaped groove, and the thickness ratio is 1.1:1 to 1.25:1. The thickness is increased to prevent the shell 1 from being broken during the sealing plastic deformation process. During the charging and discharging chemical reaction process inside the battery, gas is generated. At the end of the charging of the lithium ion battery, decomposition of the electrolyte may occur, which can cause gas to be generated. The thicker upper wall can better withstand the internal pressure brought by the gas, reduce the occurrence of bulging, and improve the safety and service life of the battery.

[0065] Referring to Figure 1 In at least one embodiment, the ratio of the wall thickness of the bottom of the shell 1 to the wall thickness of the side of the shell 1 is 1.5:1 to 2.1:1. The battery generates gas continuously during the charging and discharging process. Increasing the thickness of the bottom can prevent the bottom of the battery from bulging and deforming. The safety sheet 3 can act as a pressure relief valve. The hardness of the top cover 2 is relatively large, which is to prevent the pressure relief valve from flying out and to withstand the probe pressure during the battery test process. The material used for the top cover 2 is a cold-rolled steel plate spcc. The material of the safety sheet 3 and the bottom cover plate is 1060 aluminum. Spcc is the name of steel for cold-rolled carbon steel sheet and steel strip.

[0066] Referring to Figure 1 In at least one embodiment, the cylindrical secondary battery includes a bottom cover plate, the bottom cover plate is connected to the safety sheet 3 by welding, and the bottom cover plate contains a score. The score forms a cylindrical secondary battery current interrupt device, i.e. CID, Current Interrupt Device. When the battery is overcharged, the chemical reaction inside the battery will become abnormally violent, generating a large amount of gas, causing the internal pressure to rise sharply. The CID can timely cut off the current in this case, preventing the battery from exploding due to overcharging. The existence of the CID can greatly reduce the risk of battery explosion due to overcharging, prevent the internal pressure of the battery from continuing to rise and cause more serious safety accidents, and cause the battery to explode.

[0067] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. The above-described device embodiments are only illustrative, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, and for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. With the above ideal embodiments of the present application as the inspiration, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content in the specification, and the technical scope must be determined according to the scope of claims.

Claims

1. A cylindrical secondary battery characterized by comprising: The application relates to a cylindrical secondary battery, which comprises: a shell (1) suitable for placing a battery inside; a top cover (2) suitable for covering the opening of the shell (1); wherein a safety sheet (3) is attached to the side of the top cover (2) facing the shell (1); wherein the edge of the safety sheet (3) has a curled edge (36) covering the outer wall of the top cover (2), the diameter of the top cover (2) is 17-27 mm, and the height of the shell (1) is 60-75 mm.

2. The cylindrical secondary battery according to claim 1, wherein the curled edge (36) is a half-enclosing structure, and the joint between the curled edge (36) and the top cover (2) has at least one welding mark.

3. The cylindrical secondary battery according to claim 2, wherein the height of the curled edge (36) is 50%-70% of the thickness of the top cover (2); and the curled edge (36) has a gap with the edge of the top cover (2).

4. The cylindrical secondary battery according to claim 1, wherein the curled edge (36) is a full-enclosing structure, and the length of the curled edge (36) is 1.5-2.0 mm.

5. The cylindrical secondary battery according to claim 1, wherein the safety sheet (3) has a first protruding part (31), a second protruding part (32) and a third platform part (33) arranged in sequence in a stepped manner; the first protruding part (31) and the second protruding part (32) protrude towards the inside of the shell relative to the third platform part (33); the thickness of the second protruding part (32) is smaller than the thickness of the first protruding part (31) and the third platform part (33).

6. The cylindrical secondary battery according to claim 5, wherein the height difference between the second protruding part (32) and the third platform part (33) is 0.4-0.6 mm.

7. The cylindrical secondary battery according to claim 5, wherein the surface of the second protruding part (32) has explosion-proof notches (34), and the depth of the explosion-proof notches (34) is 20%-35% of the thickness of the second protruding part (32); the explosion-proof notches (34) are distributed in the circumferential direction.

8. The cylindrical secondary battery according to claim 1, wherein the surface of the safety sheet (3) further has at least one score line (35); the opening direction of the score line (35) is away from the direction of the top cover (2); wherein the depth of the score line (35) is 0.05-0.2 mm.

9. The cylindrical secondary battery according to claim 8, wherein the score line (35) is in a straight line shape, and the length of the score line (35) is 4-8 mm.

10. The cylindrical secondary battery according to claim 8, wherein the score line (35) is in a circumferential shape, and the angle of the score line (35) is 300-330 degrees.

11. The cylindrical secondary battery according to claim 1, wherein the thickness of the bottom of the shell (1) is greater than the thickness of the side wall of the shell (1), and the thickness ratio is 1.5:1 to 2.1:

1.

12. The cylindrical secondary battery according to claim 1, wherein a U-shaped groove is arranged on the shell (1), and the ratio of the wall thickness above the U-shaped groove to the wall thickness below the U-shaped groove is 1.1:1 to 1.25:

1. ​ 13. The cylindrical secondary battery according to claim 1, wherein the material of the case (1) is a cold-rolled steel sheet.

14. The cylindrical secondary battery according to claim 1, wherein the cylindrical secondary battery includes a bottom cover plate, the bottom cover plate is connected with the safety sheet (3) by welding, and the bottom cover plate contains a notch.

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