A top cover assembly and a power battery

Abstract

The present application provides a top cover assembly and a power battery. Among them, the top cover assembly includes: a cover plate, on one side of the cover plate, there is a receiving groove, and an explosion-proof hole is provided on the bottom wall of the receiving groove; an explosion-proof sheet, which seals the explosion-proof hole, there is a groove on the explosion-proof sheet, the side of the explosion-proof sheet with the groove faces the explosion-proof hole, the groove communicates with the explosion-proof hole, the outer edge of the groove abuts against the inner wall of the receiving groove, the size of the groove is larger than the size of the explosion-proof hole, and a through groove is formed between the explosion-proof sheet and the bottom wall of the receiving groove; a weak part, which is arranged on the bottom wall of the groove, and the weak part is exposed in the explosion-proof hole. By increasing the distance between the weak part and the inner wall of the groove, a through groove is formed between the explosion-proof sheet and the cover plate. When the gas breaks through the weak part and relieves pressure or heat through the explosion-proof hole, the through groove can play a role in providing blasting buffer, so that the actual blasting opening pressure value of the explosion-proof sheet is within a stable range, preventing the explosion-proof sheet from opening prematurely or delaying opening.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage devices, and in particular, to a top cover assembly and a power battery. Background Art

[0002] With the development of the drive power sources of more and more electric tools and new energy vehicles towards high capacity and high safety, power batteries are widely used in electric tools and new energy vehicles due to their excellent characteristics such as high capacity.

[0003] A power battery can be charged and discharged, and its internal environment is relatively sealed. During the use and transportation of the power battery, the power battery may fail due to overcharging or being punctured, resulting in a short circuit. When the power battery short-circuits, the battery cells discharge at a large current, generating a large amount of heat, burning out the diaphragm, and causing a greater short-circuit phenomenon. In this way, the battery cells will generate high temperatures, causing the electrolyte to decompose into gases, resulting in excessive internal pressure. When the outer shell of the battery cells cannot withstand this pressure, the battery will explode, which may seriously damage human health and safety in severe cases. Existing batteries usually use CID (Current Interrupt Device), SSD (Short Safety Device), explosion-proof valves (explosion-proof sheets), or other explosion-proof structures to avoid safety accidents.

[0004] In the prior art, the explosion-proof valve is installed on the top cover assembly, covering the exhaust through-hole of the top cover assembly. The explosion-proof valve needs to maintain a stable burst opening pressure value. The explosion-proof valve is provided with a weak part, such as a notch, etc., for the gas generated inside the battery cells to first rush out from the weak part, so as to achieve the purpose of pressure relief and heat dissipation. In actual use, the preset threshold for the opening of the explosion-proof valve is not a specific value, but there is a fluctuation range. However, due to the thinness of the weak part and the inconsistent strength of each part of the top cover assembly, it may cause the actual burst opening pressure value to fluctuate greatly and exceed the preset threshold, resulting in the premature opening or delayed opening of the explosion-proof valve, thereby affecting the safety performance of the power battery. Summary of the Invention

[0005] The present application provides a top cover assembly and a power battery to solve the problem of a large fluctuation range in the explosion of the explosion-proof valve of the power battery.

[0006] On the one hand, the present application provides a top cover assembly, including:

[0007] A cover plate, on one side of which there is a receiving groove, and an explosion-proof hole is provided on the bottom wall of the receiving groove;

[0008] Explosion-proof sheet, the explosion-proof sheet seals the explosion-proof hole, a groove is provided on the explosion-proof sheet, one side of the explosion-proof sheet with the groove faces the explosion-proof hole, the groove communicates with the explosion-proof hole, the outer edge of the groove abuts against the inner wall of the accommodating groove, the size of the groove is larger than the size of the explosion-proof hole, and a through groove is formed between the explosion-proof sheet and the bottom wall of the accommodating groove;

[0009] Weak part, the weak part is arranged on the bottom wall of the groove, and the weak part is exposed in the explosion-proof hole.

[0010] In a possible implementation manner of the present application, the length range of the bottom wall of the through groove is 0.3 mm - 1.5 mm.

[0011] In a possible implementation manner of the present application, the distance range between the inner wall of the groove and the weak part is greater than 0.3 mm.

[0012] In a possible implementation manner of the present application, the distance range between the inner wall of the groove and the outer side wall of the explosion-proof sheet is greater than 0.5 mm.

[0013] In a possible implementation manner of the present application, the ratio of the diameter of the explosion-proof hole to the length of the bottom wall of the through groove is greater than or equal to 0.07 and less than 1.

[0014] In a possible implementation manner of the present application, the ratio of the height of the through groove to the height of the outer side wall of the explosion-proof sheet is greater than or equal to 0.4 and less than 1.

[0015] In a possible implementation manner of the present application, the weak part is an annular weak part.

[0016] In a possible implementation manner of the present application, the annular weak part is provided with a first end and a second end, and the first end and the second end are arranged at intervals.

[0017] In a possible implementation manner of the present application, along the direction away from the bottom wall of the groove, the width of the weak part gradually increases.

[0018] On the other hand, the present application also provides a power battery, including the top cover assembly described above.

[0019] For the top cover assembly and the power battery provided by the present application, by increasing the distance between the weak part and the inner wall of the groove, a through groove is formed between the explosion-proof sheet and the cover plate, so that when the gas breaks through the weak part and relieves pressure or heat through the explosion-proof hole, the through groove can provide a blasting buffer effect for the gas, avoiding a large fluctuation range of the explosion-proof sheet, making the actual blasting opening pressure value of the explosion-proof sheet within a stable range, preventing the explosion-proof sheet from opening in advance or delaying opening, thereby improving the safety performance of the power battery. Description of the Drawings

[0020] Combined with the accompanying drawings, through a detailed description of the specific embodiments of the present application, the technical solutions and other beneficial effects of the present application will become obvious.

[0021] Figure 1 It is a schematic structural diagram of the top cover assembly provided by an embodiment of the present application.

[0022] Figure 2 Provided by an embodiment of the present application Figure 1 It is a schematic cross-sectional structure diagram of the top cover assembly in

[0023] Figure 3 Provided by an embodiment of the present application Figure 2 It is a partially enlarged schematic diagram at position A in

[0024] Figure 4 Provided by an embodiment of the present application Figure 2 It is another partially enlarged schematic diagram at position A in

[0025] Figure 5 It is a schematic structural diagram of the explosion-proof film in the top cover assembly provided by an embodiment of the present application. Specific Embodiments

[0026] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0027] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0028] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a connection that allows mutual communication; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0029] In the present application, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0030] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0031] Please refer to Figure 1 - Figure 3 An embodiment of the present application provides a top cover assembly, including a cover plate 100, an explosion-proof sheet 200, and a weak part 300.

[0032] A receiving groove 101 is provided on one side of the cover plate 100, and an explosion-proof hole 102 is provided on the bottom wall of the receiving groove 101. Among them, the explosion-proof hole 102 is used to form a pressure relief channel.

[0033] The explosion-proof film 200 seals the explosion-proof hole 102. A groove 201 is provided on the explosion-proof film 200. The side of the explosion-proof film 200 with the groove 201 faces the explosion-proof hole 102. The groove 201 communicates with the explosion-proof hole 102. The outer edge of the groove 201 abuts against the inner wall of the accommodation groove 101. The size of the groove 201 is larger than that of the explosion-proof hole 102. A through groove 202 is formed between the explosion-proof film 200 and the bottom wall of the accommodation groove 101. The weak part 300 is provided on the bottom wall of the groove 201, and the weak part 300 is exposed in the explosion-proof hole 102.

[0034] In the top cover assembly provided by the embodiment of the present application, by increasing the distance between the weak part 300 and the inner wall of the groove 201, a through groove 202 is formed between the explosion-proof film 200 and the cover plate 100. Thus, when the gas breaks through the weak part 300 and relieves pressure or heat through the explosion-proof hole 102, the through groove 202 can provide a blasting buffer effect for the gas, avoiding a large fluctuation range of the explosion-proof film, so that the actual blasting opening pressure value of the explosion-proof film is within a stable range, preventing the explosion-proof film from opening prematurely or delaying opening, thereby improving the safety performance of the power battery.

[0035] In some embodiments, the weak part 300 is a notch. The annular weak part 300 is an annular notch. The weak part 300 is an annular weak part 300. Exemplarily, the shape of the notch can be wavy, triangular, circular, arc-shaped, etc. The notch can be engraved on either side of the explosion-proof film 200. Correspondingly, the groove 201 is an annular groove 201.

[0036] In some embodiments, the distance W1 between the inner wall of the groove 201 and the weak part 300 ranges from greater than 0.3 mm. By leaving a distance greater than 0.3 mm between the inner wall of the groove 201 and the weak part 300, it is convenient to increase the thickness of the bottom wall of the weak part 300. There are multiple welding processes in the manufacturing process of the top cover assembly, such as the welding process of the explosion-proof film 200 and the cover plate 100, the ultrasonic hot melting process of the lower plastic, etc. Due to the use of various processes such as ultrasonic welding and laser welding in the welding process, during the welding process of manufacturing the top cover assembly, under the conduction of welding energy (such as ultrasonic energy, welding heat, etc.), it is easy to cause premature blasting due to the stress generated inside the explosion-proof film 200, that is, the explosion-proof film explodes when the actual air pressure value it receives is less than the preset air pressure value. By increasing the thickness of the bottom wall of the weak part 300, the tensile strength of the weak part 300 under the action of internal stress can be increased when the welding energy is transmitted to the notch area, avoiding premature opening of the explosion-proof film 200 due to the thinness of the weak part 300, thus ensuring the sensitivity of the explosion-proof film 200 and the stability of the critical pressure of blasting, which is beneficial to improving the safety performance of the power battery.

[0037] Specifically, as Figure 4As shown, the range of the reserved distance W1 between the inner wall of the groove 201 and the weak part 300 can be 0.3 mm - 3.2 mm. If the distance range is less than 0.3 mm, during subsequent processes such as forming the weak part 300, the inner wall of the groove 201 is likely to damage the processing tools for the weak part 300, such as the scoring die, etc. The ratio of the distance W1 between the inner wall of the groove 201 and the weak part 300 to the distance W2 between the inner wall of the groove 201 and the outside of the explosion-proof sheet 200 is greater than or equal to 0.16 - 0.7. Exemplarily, W1 / W2 can be 0.16, and W1 / W2 can also be 0.70. By limiting the ratio relationship of W1 / W2 within a preset proportional range in this application, while increasing the thickness of the bottom wall of the weak part, it can ensure that the explosion-proof sheet 200 is opened at a preset threshold, thereby effectively improving the safety performance of the power battery.

[0038] It should be noted that if there is not enough reserved distance between the inner wall of the groove 201 and the weak part 300, that is, W1 is too small, and only the thickness of the bottom wall of the weak part 300 is simply increased, then the blasting opening threshold of the explosion-proof sheet 200 will be increased, that is, the actual blasting opening threshold of the explosion-proof sheet 200 will exceed the preset blasting opening threshold. Then the explosion-proof sheet 200 cannot be opened when reaching the preset blasting threshold, which may lead to the inability to relieve pressure and heat in the power battery in time, and is not conducive to improving the safety performance of the power battery.

[0039] In some embodiments, the distance range between the inner wall of the groove 201 and the outer wall of the explosion-proof sheet 200 is greater than 0.5 mm. Specifically, the range of the reserved distance (i.e., the difference between W1 and W2) between the inner wall of the groove 201 and the outer wall of the explosion-proof sheet 200 can be 0.5 mm - 2 mm, as Figure 4 shown. Since a welding bead width required for welding needs to be reserved during the welding process of the explosion-proof sheet 200 and the cover plate 100, setting the distance between the inner wall of the groove 201 and the outer wall of the explosion-proof sheet 200 within a preset range is conducive to ensuring the smooth progress of the welding process. At the same time, making the distance between the inner wall of the groove 201 and the outer wall of the explosion-proof sheet 200 as small as possible is conducive to saving the production materials of the explosion-proof sheet 200 and reducing the production cost.

[0040] In some embodiments, such as Figure 4As shown, the length of the bottom wall of the through groove 202 is L1. Specifically, the bottom wall of the through groove 202 is the bottom wall of the bottom wall of the accommodating groove 101 that is opposite to the explosion-proof sheet 200. Among them, the range of L1 is 0.3-1.5 mm. For example, the length of L1 can be 0.3 mm, 0.5 mm, 1 mm, 1.5 mm, etc. It should be noted that in the embodiment of the present application, in order to ensure the smooth progress of the explosion, that is, to prevent the notch from being blocked by the bottom wall of the through groove 202 and unable to be opened smoothly, the relationship between L1 and W1 is set as W1≥L1. For example, when the value of W1 is 1 mm, the value of L1 is 0.5 mm. The ratio of the diameter D of the explosion-proof hole 102 to the length L1 of the bottom wall of the through groove 202 is greater than or equal to 0.07 and less than 1. Exemplarily, the ratio of D / L1 can be 0.07, 0.1, 0.5, 0.8, etc. In the embodiment of the present application, by limiting the ratio relationship of D / L1 within a preset proportional range, the width of the through groove 202 can be adjusted by adjusting the length L1 of the bottom wall of the through groove 202, so that the magnitude of the provided blasting buffer can be controlled. At the same time, since the explosion-proof hole 200 is used to provide a pressure relief channel, therefore, through the ratio relationship of D / L1, while controlling the magnitude of the provided blasting buffer, the smooth progress of pressure relief and heat dissipation of the explosion-proof sheet 200 can be ensured, thereby ensuring the safety performance of the power battery.

[0041] In some embodiments, the ratio of the height H2 of the through groove 202 to the height H1 of the outer side wall of the explosion-proof sheet 200 is greater than or equal to 0.4 and less than 1. The ratio of H2 / H1 can be 0.4, 0.6, 0.8, etc. In the present application, by limiting the ratio relationship of H2 / H1 within a preset proportional range, since the height of H1 is fixed in products of the same model, the magnitude of the provided blasting buffer can be controlled by controlling the height H2 of the through groove, and at the same time, the blasting opening value can be ensured to be within the preset range, further reducing the damage caused by the blasting impact force to other components of the top cover assembly, and ensuring that the explosion-proof sheet 200 can be opened in time, further improving the safety performance of the power battery.

[0042] In some embodiments, such as Figure 5As shown, the annular weak part 300, i.e., the notch, is provided with a first end 301 and a second end 302, and the first end 301 and the second end 302 are spaced apart. In this embodiment, the notch is formed into a non-closed ring through the first end 301 and the second end 302, and a spaced position 303 is formed between the first end 301 and the second end 302. Among them, the spaced position 303 is a part reserved on the annular line where the explosion-proof notch is located without setting a weak explosion-proof notch. When the power battery explodes at a certain pressure value, the explosion-proof sheet 200 ruptures along the explosion-proof notch and tilts relative to the cover plate 100, and the connecting part of the explosion-proof sheet 200 and the cover plate 100 at the spaced position 303 always remains connected, and the whole explosion-proof sheet 200 will not be completely separated and washed away, thus ensuring the safety performance of the explosion-proof sheet 200 during explosion.

[0043] It can be understood that the notch can also be set as a closed annular notch, and by setting the thickness of the notch bottom wall of a certain section on the annular line to be greater than that of other parts, a thickened position is formed. Similarly, when the power battery explodes at a certain pressure threshold, the explosion-proof sheet 200 ruptures along the explosion-proof notch and tilts relative to the cover plate 100, and the explosion-proof sheet 200 and the cover plate 100 always remain connected at the thickened position, so that the whole explosion-proof sheet 200 will not be completely separated and washed away, and the safety performance of the explosion-proof sheet 200 during explosion can also be ensured.

[0044] In some embodiments, along the direction away from the bottom wall of the groove 201, the width of the notch gradually increases. Specifically, as Figure 2 shown, in the cross-sectional direction of the explosion-proof sheet 200, the notch is arranged in an inverted trapezoid. Compared with setting the notch in a rectangular shape in the cross-sectional direction of the explosion-proof sheet 200, setting the notch in an inverted trapezoid is more convenient for the notch processing process and is beneficial to simplifying the process.

[0045] In some embodiments, the top cover assembly further includes a protective patch 400. A boss 103 is provided around the edge of the explosion-proof hole 102. Specifically, the opening of the groove 201 is arranged towards the side where the boss 103 is located, and the protective patch 400 is adhered to the boss 103 to cover the explosion-proof sheet 200.

[0046] On the other hand, in order to better implement the top cover assembly of the present application, the embodiments of the present application also provide a power battery including the above-mentioned top cover assembly. Since this power battery has the above-mentioned top cover assembly, it has all the same beneficial effects, and the present application will not elaborate here.

[0047] In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0048] The above has introduced in detail a top cover assembly and a power battery provided by the embodiments of the present application. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A top cover assembly, characterized in that, Comprising: A cover plate, on one side of which there is a receiving groove, and an explosion-proof hole is provided on the bottom wall of the receiving groove; An explosion-proof sheet for sealing the explosion-proof hole, with a groove provided on the explosion-proof sheet, the side of the explosion-proof sheet with the groove facing the explosion-proof hole, the groove communicating with the explosion-proof hole, the outer edge of the groove abutting against the inner wall of the receiving groove, the size of the groove being larger than the size of the explosion-proof hole, and a through groove being formed between the explosion-proof sheet and the bottom wall of the receiving groove; A weak part provided on the bottom wall of the groove, and the weak part is exposed in the explosion-proof hole; The reserved distance W1 between the inner wall of the groove and the weak part ranges from 0.3 mm to 3.2 mm; the ratio of the distance W1 between the inner wall of the groove and the weak part to the distance W2 between the inner wall of the groove and the outside of the explosion-proof sheet is greater than or equal to 0.16 - 0.7; the ratio of the diameter D of the explosion-proof hole to the length L1 of the bottom wall of the through groove is greater than or equal to 0.07 and less than 1; the ratio of the height H2 of the through groove to the height H1 of the outer wall of the explosion-proof sheet is greater than or equal to 0.4 and less than 1.

2. The top cover assembly according to claim 1, characterized in that The length range of the bottom wall of the through groove is 0.3 mm - 1.5 mm.

3. The top cover assembly according to claim 1, characterized in that, The distance range between the inner wall of the groove and the outer wall of the explosion-proof sheet is greater than 0.5 mm.

4. The top cover assembly according to claim 1, characterized in that, The weak part is an annular weak part.

5. The top cover assembly according to claim 4, characterized in that The annular weak part is provided with a first end and a second end, and the first end and the second end are spaced apart.

6. The top cover assembly according to claim 1, wherein Along the direction away from the bottom wall of the groove, the width of the weak part gradually increases.

7. A power battery, characterized in that, Including the top cover assembly according to any one of claims 1 - 6.

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