Explosion-proof valve for cell top cover, and cell top cover

Abstract

To provide an explosion-proof valve for a cell top cover especially regarding the field of cells.SOLUTION: An explosion-proof valve includes a rupture disc, a burst ring, and a connecting portion. The rupture disc includes an internal platform and an external platform arranged around the internal platform, and a thickness of the internal platform is greater than a thickness of the external platform. The burst ring is arranged around an outer circumference of the external platform, and a thickness of the burst ring is smaller than the thickness of the external platform. The burst ring is a recess recessed from a top face of the explosion-proof valve to a bottom face of the explosion-proof valve, the connecting portion is arranged around an outer circumference of the burst ring, and the connecting portion is connected to the burst ring. The explosion-proof valve for a cell top cover provided according to the embodiments is beneficial for improving the safety performance of a battery.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] TECHNICAL FIELD The embodiments of the present disclosure relate to the technical field of batteries, and in particular to an explosion-proof valve for a cell top cover and a cell top cover. [Background technology]

[0002] When a battery experiences thermal runaway, it will rapidly release the electrical and chemical energy stored in the cell, causing the electrolyte and chemicals inside it to decompose rapidly, producing a large amount of gas, which will then cause the pressure inside the battery to rise rapidly. To prevent the pressure on the inner wall of the cell from becoming too high and causing an explosion, the cell is often equipped with an explosion-proof valve to release the pressure.

[0003] The explosion-proof valve is provided with a weak part for bursting. Under normal conditions, the air pressure inside the battery is stable and lower than the explosion pressure threshold of the explosion-proof valve, in which case the explosion-proof valve maintains a sealed state and blocks the influence of the external environment on the inside of the battery. When an abnormality occurs in the battery, a large amount of gas is generated inside the cell, causing the pressure inside the cell to rise and reach the explosion pressure threshold of the explosion-proof valve, the weak part of the explosion-proof valve bursts to release the gas inside the cell, achieving the purpose of releasing pressure and avoiding the risk of explosion caused by the pressure inside the battery being too high. Summary of the Invention [Problem to be solved by the invention]

[0004] The embodiments of the present disclosure provide an explosion-proof valve and a cell top cover, which are advantageous in at least improving the safety of the battery. [Means for solving the problem]

[0005] According to some embodiments of the present disclosure, the embodiment of the present disclosure provides an explosion-proof valve of a cell top cover, the explosion-proof valve has opposing upper and lower surfaces, the explosion-proof valve includes a rupture disk, an explosion mark, and a connection part, the rupture disk includes an inner platform and an outer platform arranged around the outer periphery of the inner platform, the thickness of the inner platform is greater than the thickness of the outer platform, the explosion mark includes a recess arranged around the outer periphery of the outer platform between the outer platform and the connection part, the thickness of the explosion mark is smaller than the thickness of the outer platform, the recess is recessed from the upper surface of the explosion-proof valve to the lower surface of the explosion-proof valve, the connection part is arranged around the outer periphery of the explosion mark, and the connection part is connected to the explosion mark.

[0006] In some embodiments, the connection portion includes a first outer ring portion and a second outer ring portion, the first outer ring portion being disposed around an outer periphery of the explosive indentations and connected to the explosive indentations, the second outer ring portion being disposed around an outer periphery of the first outer ring portion and connected to the first outer ring portion, and wherein a thickness of the first outer ring portion is less than or equal to a thickness of the second outer ring portion and wherein a thickness of the first outer ring portion is greater than or equal to a thickness of the outer platform.

[0007] In some embodiments, the thickness range of the second outer ring portion is 0.3 mm to 0.7 mm.

[0008] In some embodiments, the ratio of the thickness of the inner platform to the thickness of the second outer ring portion is between 0.4 and 2.

[0009] In some embodiments, the rupture disk further comprises a first slope portion, the first slope portion is connected between the outer platform and the inner platform, and the thickness of the first slope portion gradually increases in the direction from the outer platform to the inner platform.

[0010] In some embodiments, the first inclined portion includes a first inclined surface and a bottom surface opposite to the first inclined surface, the bottom surface being a part of the lower surface, where the first inclined surface connects a surface of the inner platform and a surface of the outer platform, and an angle between the first inclined surface and a normal line perpendicular to the bottom surface is between 60° and 89°.

[0011] In some embodiments, the explosion-proof valve further includes an inner recess, the inner platform being surrounded by an outer periphery of the inner recess, the inner recess being recessed from the upper surface toward the lower surface, and wherein a thickness of the inner recess is greater than a thickness of the explosion indentation.

[0012] In some embodiments, the thickness of the inner recess is less than or equal to the thickness of the connecting portion.

[0013] In some embodiments, the rupture disk further comprises a second inclined portion, the second inclined portion is connected between the inner platform and the inner recess, and the thickness of the second inclined portion gradually decreases in the direction from the inner platform to the inner recess.

[0014] In some embodiments, the thickness range of the explosive indentations is between 0.01 mm and 0.15 mm.

[0015] According to some embodiments of the present disclosure, in another form of the embodiments of the present disclosure, a cell top cover is provided, the cell top cover including a pole and an aluminum reflective sheet, the aluminum reflective sheet is provided with a pole through hole, and the pole is drilled in the pole through hole, and the cell top cover further includes an explosion-proof valve of the cell top cover described in any one of the above embodiments. Effect of the Invention

[0016] The technical solutions provided in the embodiments of the present disclosure have at least the following advantages: The explosion-proof valve of the cell top cover provided in the embodiment of the present disclosure has an upper surface and a lower surface facing each other, the explosion-proof valve includes a rupture disk, an explosion mark, and a connection part, the rupture disk is used to guide the direction of the blowout air flow when the explosion-proof valve is opened, and in a normal state, the rupture disk is connected to the explosion mark, so that the explosion-proof valve is kept in a sealed state. The rupture disk includes an inner platform and an outer platform that is arranged around the outer periphery of the inner platform, the outer platform is connected to the inner platform, and the thickness of the inner platform is greater than the thickness of the outer platform, thereby increasing the thickness of the rupture disk, improving the strength of the rupture disk, avoiding the rupture disk being easily deformed, avoiding the deformation of the rupture disk to apply pressure to the explosion mark, avoiding the change of the explosion threshold of the explosion mark, and improving the safety of the battery. The explosion mark is provided around the outer periphery of the outer platform, and the thickness of the explosion mark is smaller than the thickness of the outer platform, which contributes to opening the explosion-proof valve at the explosion mark, and the opening pressure threshold of the explosion-proof valve can be controlled, thereby improving the safety of the battery. The explosion mark is a depression recessed from the upper surface to the lower surface, which avoids the formation of crystals at the explosion mark due to chemical reactions inside the battery, and avoids the influence of the adhesion of crystals on the opening of the explosion mark. The connection part is used to connect the explosion-proof valve and the cell top cover, and the connection part is provided around the outer periphery of the explosion mark and is connected to the explosion mark. [Brief description of the drawings]

[0017] One or more embodiments are illustratively described in the figures in the corresponding attached drawings, but these illustrative descriptions are not intended to limit the embodiments, and unless otherwise specified, the figures in the attached drawings are not limited to scale. In order to more clearly explain the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below, but obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can obtain other drawings based on these drawings without creative labor. [Figure 1] FIG. 1 is a diagram showing a top view structure of an explosion-proof valve of a cell top cover in one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing a bottom view of the explosion-proof valve of the cell top cover in one embodiment of the present disclosure. [Diagram 3] FIG. 3 is a diagram showing a top view structure of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram showing a front view of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure. [Diagram 5] FIG. 5 is a diagram showing a top view structure of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure. [Figure 6] FIG. 6 is a diagram showing a top view structure of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram showing a front view of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure. [Figure 8] FIG. 8 is a diagram showing a top view structure of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure. [Figure 9] FIG. 9 is a diagram showing the structure of a cell top cover in another embodiment of the present disclosure. [Figure 10] FIG. 10 is a diagram showing a top view structure of an aluminum reflecting sheet of a cell top cover in another embodiment of the present disclosure. [Figure 11]FIG. 11 is a diagram showing a bottom view of the aluminum reflecting sheet of a cell top cover in another embodiment of the present disclosure. [Figure 12] FIG. 12 is a diagram showing another structure of a cell top cover in another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] As can be seen from the background art, a stable explosion pressure threshold is the key to the successful use of an explosion-proof valve.

[0019] However, in reality, the explosion pressure threshold of the explosion-proof valve is affected by a combination of various factors, so the difference between the explosion pressure threshold of the battery product and the designed explosion pressure threshold will be large, which will lead to the explosion-proof valve not being able to be used normally and will pose a safety risk to the battery.

[0020] Analysis shows that the structure of the explosion-proof valve is the key to reducing the explosion pressure threshold of the explosion-proof valve. During the production and assembly process, the seat structure of the explosion-proof valve will be deformed under the influence of external stress, and the stress will be concentrated on the weak parts of the explosion-proof valve, reducing the explosion pressure threshold of the explosion-proof valve, and the explosion-proof valve will open at a pressure lower than the designed explosion pressure threshold, which will affect the normal use of the battery. In addition, during the use of the battery, the normal chemical reaction inside the battery will generate an internal pressure cycle inside the battery, which will cause some areas of the explosion-proof valve to rise and fall, which will also apply stress to the weak parts and reduce the explosion pressure threshold of the explosion-proof valve.

[0021] In the embodiment of the present disclosure, an explosion-proof valve of a cell top cover is provided, the explosion-proof valve includes a rupture disk with an outer platform and an inner platform, an explosion mark, and a connection part, and the thickness of the inner platform is greater than the thickness of the outer platform, thereby increasing the thickness of the rupture disk, thereby improving the strength of the rupture disk and avoiding deformation during the manufacturing and assembly process of the rupture disk. The thickness of the explosion mark is lower than the thickness of other parts of the explosion-proof valve, and is a weak part of the explosion-proof valve. The explosion mark is arranged around the outer periphery of the outer platform, and when the explosion-proof valve is opened, the explosion mark is torn, the rupture disk opens, and the pressure inside the battery is released. In the normal use process of the battery, the thickness of the rupture disk can be increased to prevent the explosion-proof valve from rising and falling due to the internal pressure cycle, and the explosion mark can be prevented from being stressed, and the explosion pressure threshold of the explosion-proof valve can be prevented from being lowered.

[0022] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. However, as will be understood by those skilled in the art, in order to allow the reader to better understand the present disclosure, many technical details are proposed in each embodiment of the present disclosure, but the technical solution that the present disclosure seeks to protect can be realized without these technical details and various changes and modifications based on the following embodiments.

[0023] FIG. 1 is a diagram showing a top view structure of an explosion-proof valve of a cell top cover in one embodiment of the present disclosure, FIG. 2 is a diagram showing a bottom view structure of an explosion-proof valve of a cell top cover in one embodiment of the present disclosure, FIG. 3 is a diagram showing a top view structure of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure, FIG. 4 is a diagram showing a front view structure of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure, FIG. 5 is a diagram showing a top view structure of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure, FIG. 6 is a diagram showing a top view structure of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure, FIG. 7 is a diagram showing a front view structure of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure, and FIG. 8 is a diagram showing a top view structure of an explosion-proof valve of another cell top cover in one embodiment of the present disclosure.

[0024] As shown in Figure 1 and Figure 2, the explosion-proof valve 100 of the cell top cover provided by one embodiment of the present disclosure has an upper surface 11 and a lower surface 12 opposite to each other. The explosion-proof valve 100 includes a rupture disk 101, an explosion slit 102, and a connection part 103. The rupture disk 101 includes an inner platform 104 and an outer platform 105.

[0025] In some embodiments, the material of the explosion-proof valve may be aluminum or aluminum alloy. For example, the material of the explosion-proof valve may be 1060 aluminum material. The 1060 aluminum material has an aluminum purity of up to 99.6%, good formability, and can withstand various pressing, pulling or bending processes, which is convenient for industrially manufacturing explosion-proof valves with special shapes. The 1060 aluminum material has excellent corrosion resistance, which helps to avoid the explosion-proof valve being corroded by the electrolyte in the battery and the strength of the explosion-proof valve being reduced. For example, the material of the explosion-proof valve may be a 3000 series aluminum alloy, such as 3003 aluminum alloy, 3105 aluminum alloy or 3A21 aluminum alloy. The 3000 series aluminum alloy is an aluminum-manganese alloy series, and has a high doping amount of manganese, which can effectively improve the corrosion resistance of the aluminum alloy and prevent the explosion-proof valve from being corroded by the electrolyte and the strength of the explosion-proof valve being reduced. Doping with manganese improves the welding performance of the aluminum alloy, which is useful for welding and fixing the explosion-proof valve and the battery structure, preventing the welded parts from bursting due to the impact of pressure when the explosion-proof valve is released, and contributing to maintaining the structural integrity of the battery.

[0026] In some embodiments, the explosion-proof valve can be formed by an extrusion molding process. Extrusion molding is a plastic processing method, in which pressure is applied to a metal blank placed in a die cavity, causing directional plastic deformation of the metal blank, and then extruding it through a die hole of an extrusion die to obtain a part or semi-finished product with a desired cross-sectional shape and dimensions and certain mechanical performance. Due to the process characteristics of extrusion molding, it can be used not only to produce rod, pipe or wire products with a simple cross-sectional shape, but also to manufacture structures with complex cross-sectional shapes, which is useful for mass production of explosion-proof valve structures with complex shapes. In addition, extrusion molding products have high precision, good product surface quality, and good matching with light metals such as aluminum or light alloys such as aluminum alloys, which can reduce the product reject rate and effectively increase the material utilization rate and yield.

[0027] In some embodiments, the explosion-proof valve may be capsule-shaped. The capsule shape is a shape in which the middle part is a quadrilateral and two opposite sides of the quadrilateral extend as an arch, so that the whole is shaped like a capsule. Here, the straight side of the arch overlaps with the straight side of the rectangle. The symmetrical structure helps to uniform the force on the explosion-proof valve, prevent the stress on the explosion-proof valve from concentrating on a certain area and causing the explosion-proof valve to open unexpectedly, and ensure that the explosion-proof valve can be used normally. And the arch design reduces the cusp angle of the explosion-proof valve, which is beneficial for processing and production. For example, in extrusion molding, the material of the rounded workpiece is easier to flow smoothly through the die compared to the workpiece with an arch, and the stress on the corner of the workpiece is also smaller, so that the quality of the explosion-proof valve can be improved.

[0028] The rupture disk 101 is one of the components of the explosion-proof valve 100 of the cell top cover, and is used to guide the direction of the ejected airflow when the explosion-proof valve 100 of the cell top cover is opened, thereby preventing the small amount of electrolyte contained in the airflow from splashing and preventing corrosion of the battery structure.

[0029] The rupture disk 101 includes an inner platform 104 and an outer platform 105 that is disposed around the outer periphery of the inner platform 104, and the outer platform 105 is connected to the inner platform 104, and the thickness of the inner platform 104 is greater than the thickness of the outer platform 105. This increases the strength of the rupture disk 101, avoids the deformation of the rupture disk 101, reduces the stress of the rupture disk 101 that the explosion mark 102 receives, and helps to avoid the change of the explosion threshold of the explosion mark 102, thereby improving the safety of the battery.

[0030] In some embodiments, the thickness of the outer platform 105 is greater than the thickness of the explosion mark 102. This allows the opening location of the explosion-proof valve to be accurately controlled to the explosion mark location, avoiding the problem that the opening location of the explosion-proof valve is not fixed, which is helpful in controlling the direction of the gas spouting out after the explosion-proof valve is opened, and can avoid the small amount of electrolyte contained in the gas spouting out from corroding the battery structure, which contributes to improving the safety of the battery.

[0031] In some embodiments, the thickness of the internal platform 104 may be equal to or less than the thickness of the connecting portion 103. In other embodiments, the thickness of the internal platform 104 may be greater than the thickness of the connecting portion 103. The thickness of the internal platform is affected by the explosion-proof valve manufacturing process. For example, when the explosion-proof valve is manufactured by the extrusion molding process, the material has high plastic deformation ability, so that the material of a part of the explosion-proof valve is pressed against the internal platform, and the thickness of the internal platform is greater than the thickness of the connecting portion. This can increase the thickness of the rupture disk, and at least increase the strength of the rupture disk, which helps to avoid the rupture disk being easily deformed, and improves the safety of the battery.

[0032] In some embodiments, as shown in FIG. 3, the rupture disk 101 may further include a first inclined portion 106. The first inclined portion 106 is connected between the outer platform 105 and the inner platform 104, and the thickness of the first inclined portion 106 gradually increases in the direction from the outer platform 105 to the inner platform 104, so that the inner edge of the first inclined portion 106 toward the inner platform 104 has the same thickness as the inner platform 104, and the outer edge of the first inclined portion 106 toward the outer platform 105 has the same thickness as the outer platform 105. The first inclined portion forms a transition between the outer platform and the inner platform, thereby reducing the manufacturing difficulty of the explosion-proof valve. In addition, the first inclined portion reduces the stress of the edge and corner structure of the explosion-proof valve, which avoids the edge and corner of the explosion-proof valve from being damaged due to excessive stress concentration, and contributes to improving the quality of the product.

[0033] In some embodiments, as shown in FIG. 4, the first inclined portion 106 includes a first inclined surface 13 and a bottom surface 14 facing the first inclined surface 13, and the bottom surface 14 is a part of the lower surface 12. Here, the first inclined surface 13 connects the surface of the inner platform 104 and the surface of the outer platform 105, and the angle between the first inclined surface 13 and a normal line perpendicular to the bottom surface 14 is 60°-89°, and may be, for example, 60°, 75°, 85°, or 89°, etc. As can be understood, as long as the first inclined portion can play a role in connecting the thickness of the outer platform and the thickness of the inner platform, the angle between the first inclined surface and the normal line perpendicular to the bottom surface can be freely set according to the type of processing process of the explosion-proof valve.

[0034] In some embodiments, as shown in FIG. 5, the explosion-proof valve 100 may include an inner recess 107. The inner recess 107 is located in the central region of the rupture disk 101, and the inner recess 107 is recessed from the upper surface 11 to the lower surface 12 of the explosion-proof valve 100, and the inner platform 104 surrounds the outer periphery of the inner recess 107. The process of forming the inner recess includes a press molding process, and the explosion-proof valve formed by the press and the template can be reprocessed. In the process of forming the explosion-proof valve, it is inevitable that the explosion-proof valve will have an uneven surface. By forming the inner recess, the unevenness of the explosion-proof valve surface can be reduced, and an explosion-proof valve with better surface quality can be obtained, which can avoid the quality problem caused by uneven stress on the explosion-proof valve surface, and help improve the safety of the battery.

[0035] In some embodiments, the thickness of the inner recess 107 may be greater than the thickness of the explosion increment 102, which can avoid the explosion-proof valve being opened at the inner recess without being opened at the explosion increment, or the explosion-proof valve being opened at the inner recess and the explosion increment at the same time, which helps to control the position where the explosion-proof valve is opened, and controls the direction of the airflow inside the battery after the explosion-proof valve is opened, and prevents a small amount of electrolyte carried away by the airflow from corroding the battery structure.

[0036] In some embodiments, the thickness of the inner recess 107 may be equal to or less than the thickness of the connecting portion 103. In other embodiments, the thickness of the inner recess 107 may be greater than the thickness of the connecting portion 103. Depending on the manufacturing process, the thickness of the inner recess can be freely set. As can be understood, in either manufacturing process, the thickness of the inner recess is less than the thickness of the inner platform.

[0037] In some embodiments, as shown in FIG. 6, the rupture disk 101 may further include a second inclined portion 108. The second inclined portion 108 is connected between the inner platform 104 and the inner recess 107, and the thickness of the second inclined portion 108 gradually decreases in the direction from the inner platform 104 to the inner recess 107. The second inclined portion forms a transition between the inner recess and the inner platform, which reduces the manufacturing difficulty of the explosion-proof valve. In addition, the second inclined portion reduces the stress of the edge and corner structure of the explosion-proof valve, which avoids the edge and corner of the explosion-proof valve from being damaged due to excessive stress concentration, which is helpful to improve product quality.

[0038] In some embodiments, as shown in FIG. 7, the second inclined portion 108 includes a second inclined surface 15 and a second bottom surface 16 facing the second inclined surface 15, and the second bottom surface 16 is a part of the lower surface 12. Here, the second inclined surface 15 connects the surface of the inner platform 104 and the surface of the inner recess 107, and the angle between the second inclined surface 15 and a normal line perpendicular to the second bottom surface 16 is less than 30°, and may be, for example, 30°, 28°, 15°, or 9°, etc. As can be understood, as long as the second inclined portion can play a role in connecting the thickness of the inner platform and the thickness of the inner recess, the angle between the second inclined surface and the normal line perpendicular to the second bottom surface can be freely set according to the processing process of the explosion-proof valve.

[0039] As shown in FIG. 1, the explosion notch 102 is also one of the components of the explosion-proof valve 100 of the cell top cover. The explosion notch 102 is provided around the outer periphery of the outer platform 105, and is a recess recessed from the upper surface 11 to the lower surface 12. The thickness of the explosion notch 102 is smaller than the thickness of the outer platform 105, and is the thinnest area of ​​the explosion-proof valve 100 of the cell top cover. When an abnormality occurs in the chemical reaction inside the battery, the pressure inside the battery gradually becomes larger than the pressure outside the battery. When the pressure inside the battery reaches the explosion threshold of the explosion notch, the explosion notch is torn, an opening is formed in the explosion-proof valve, and the gas inside the explosion-proof valve is discharged, and the pressure inside the explosion-proof valve and the pressure outside the explosion-proof valve are balanced, so as to avoid the explosion of the battery.

[0040] In some embodiments, the thickness range of the explosion increment is 0.01mm to 0.15mm, and may be, for example, 0.01mm, 0.02mm, 0.12mm, or 0.15mm. By controlling the thickness of the explosion increment, the explosion threshold of the explosion increment can be controlled, thereby designing the explosion increment to open at an appropriate pressure and avoiding affecting the normal use of the battery. For example, by avoiding the explosion increment to suddenly open under the normal use of the battery, leakage of electrolyte can be avoided. In addition, for example, it can be avoided that the explosion increment does not open even if it reaches the explosion pressure of the battery, and the explosion-proof valve loses its explosion-proof function.

[0041] In some embodiments, the cross-sectional shape of the depression may be an inverted trapezoid with a height of 0.18 mm, a long side length of 0.3 mm, and a short side length of 0.2 mm. As can be seen, when designing the explosion indentation, characteristics such as different cross-sectional shapes, deployment lengths, depression depths, and depression widths can be changed according to the set explosion threshold to adapt to different usage scenarios.

[0042] In some embodiments, the explosion-proof valve further comprises a reinforcing rib, and the thickness of the reinforcing rib is greater than the thickness of the explosion mark.The reinforcing rib is located in a part of the area of ​​the recess, and is used to strengthen the connection between the explosion mark and the external platform and the connection part, so as to avoid the explosion mark being completely torn off when the explosion-proof valve is opened, to avoid the rupture disk being separated, and to prevent the rupture disk being separated from the other structures inside the battery, thereby contributing to improving the safety of the battery.

[0043] In some embodiments, the thickness of the reinforcing rib may be 0.16mm to 0.25mm, such as 0.16mm, 0.18mm, 0.21mm, or 0.25mm, etc. As can be understood, as long as the reinforcing rib can play a role in strengthening the connection between the explosion indentation and the external platform and the connection part, the thickness of the reinforcing rib can be freely set.

[0044] In some embodiments, the expansion length of the reinforcing rib may be 1 / 6 or less of the expansion length of the explosion indentation. This can avoid the occurrence of the problem that the tearable part of the explosion indentation is too short, which affects the gas discharge ability of the explosion-proof valve, and at least improve the explosion-proof effect of the explosion-proof valve, and thus improve the safety of the battery. As can be seen, the proportion of the expansion length of the reinforcing rib to the expansion length of the explosion indentation needs to be set in combination with the structure of the explosion indentation.

[0045] In some embodiments, the explosion-proof valve of the cell top cover may include an installation mark. The installation mark may be provided on the underside. The installation mark may also be provided adjacent to the reinforcing rib. The purpose of providing the installation mark is to improve the visibility of the installation direction of the explosion-proof valve on the cell top cover. This standardizes the installation direction of the explosion-proof valve, guides the direction of the airflow inside the cell after the explosion-proof valve is opened, and prevents the airflow from destroying the internal structure of the battery, which helps improve the safety of the battery.

[0046] In some embodiments, the shape of the attachment mark may be a letter shape. In other embodiments, the shape of the attachment mark may be a pattern. As can be appreciated, the shape of the attachment mark may be any shape as long as the attachment mark is visible.

[0047] As shown in FIG. 1, the connection part 103 is also one of the components of the explosion-proof valve 100 of the cell top cover. The connection part 103 is provided around the outer periphery of the explosion marking 102, and the connection part 103 is connected to the explosion marking 102. The role of the connection part is to facilitate the connection of the explosion-proof valve and the cell top cover. In some embodiments, the connection part and the cell top cover are welded together to fix the explosion-proof valve and the cell top cover, seal the cell, and prevent the electrolyte inside the cell from leaking.

[0048] In some embodiments, as shown in FIG. 8, the connection portion 103 includes a first outer ring portion 109 and a second outer ring portion 110. The first outer ring portion is provided around the outer periphery of the explosion marking 102, and the first outer ring portion 109 is connected to the explosion marking 102. The first outer ring portion is used to connect the second outer ring portion and the explosion marking. The second outer ring portion 110 is provided around the outer periphery of the first outer ring portion 109, and the second outer ring portion 110 is connected to the first outer ring portion 109. The second outer ring portion is used to provide a contact surface and contributes to the connection between the explosion-proof valve and the cell top cover. In this way, by dividing a specific area to facilitate the connection between the explosion-proof valve and the cell top cover, the standardization degree of the explosion-proof valve is increased, which helps to improve the assembly efficiency and improves the production efficiency, and also avoids quality problems caused by imperfect alignment during the assembly of the explosion-proof valve and the cell top cover, thereby contributing to improving the safety of the battery.

[0049] In some embodiments, the thickness of the first outer ring portion 109 is equal to or less than the thickness of the second outer ring portion 110. To simplify the processing of the explosion markings, the thickness of the first outer ring portion may be smaller than the thickness of the second outer ring portion, and the thickness of the first outer ring portion is greater than the thickness of the explosion markings. For example, when processing an explosion-proof valve in an extrusion molding process, explosion markings with accurate dimensions cannot usually be formed, and it is necessary to perform secondary processing on the explosion-proof valve after extrusion molding, and etch explosion markings with accurate dimensions on the explosion-proof valve. To simplify the etching process, the thickness of the first outer ring portion may be smaller than the thickness of the second outer ring portion.

[0050] In some embodiments, the thickness of the first outer ring 109 is equal to or greater than the thickness of the outer platform 105. The thickness of the first outer ring may be equal to the thickness of the outer platform, which is helpful in processing the explosion notches. The thickness of the first outer ring may be greater than the thickness of the outer platform, which can avoid changing the thickness of the explosion-proof valve, provide the first outer ring with a certain strength, avoid the first outer ring being deformed during processing and / or use, and avoid applying stress to the explosion notches, thus avoiding the explosion threshold of the explosion notches from changing, which contributes to improving the safety of the battery.

[0051] In some embodiments, the thickness range of the second outer ring portion 110 is 0.3 mm to 0.7 mm, for example, 0.3 mm, 0.4 mm, 0.5 mm, or 0.7 mm. In some embodiments, the thickness of the second outer ring portion is the same as the thickness of the substrate forming the explosion-proof valve. Since the second outer ring portion is a part that connects the explosion-proof valve and the cell top cover, the second outer ring portion needs to have a certain thickness, so as to avoid the problem of the explosion-proof valve and the cell top cover falling off due to the second outer ring portion being too thin, and to avoid affecting the safety of the battery. At the same time, the second outer ring portion should not be too thick, so as not to occupy more space than necessary for other structures in the cell top cover, which helps to avoid wasting materials.

[0052] In some embodiments, the ratio of the thickness of the inner platform 104 to the thickness of the second outer ring portion 110 is 0.4 to 2, for example, it may be 0.4, 0.5, 1.9 or 2. At least, it can avoid the situation that the explosion-proof valve is difficult to adhere to the cell top cover because of the inner platform being too thick, and it can also avoid the situation that the rupture disk is not strong enough and easily deformed because of the inner platform being too thin.

[0053] The explosion-proof valve 100 of the cell top cover provided in the above embodiment includes a rupture disk 101, an explosion mark 102, and a connection part 103. When the cell is in normal use, the rupture disk 101 is used to seal the cell, and prevents the electrolyte inside the cell from leaking. When the explosion-proof valve 100 is opened, the rupture disk 101 opens to form an opening, which serves to exhaust the gas inside the cell, balance the gas pressure inside and outside the cell, and prevent the cell from exploding. The rupture disk 101 includes two parts, an inner platform 104 and an outer platform 105, the outer platform 105 is disposed around the outer periphery of the inner platform 104, and the thickness of the inner platform 104 is greater than the thickness of the outer platform 105. This increases the strength of the rupture disk 101, prevents the rupture disk 101 from being deformed under force during installation and / or use, and helps to prevent the explosion notches 102 connected to the rupture disk 101 from being destroyed by stress, thereby improving the safety of the battery. The explosion notches 102 are provided around the outer periphery of the outer platform 105 of the rupture disk and are the thinnest part of the explosion-proof valve 100, and are used to open when the pressure inside the cell exceeds the safety threshold. By providing the explosion notches 102, the opening location of the explosion-proof valve 100 can be controlled, which helps to improve the safety of the battery. In addition, the explosion notches 102 are recesses recessed from the upper surface 11 to the lower surface 12 of the explosion-proof valve, which prevents the electrolyte from forming crystals at the explosion notches 102 during reaction, and ensures that the explosion threshold of the explosion notches 102 is not affected. The connection part 103 is provided around the outer periphery of the explosion notches 102 and is connected to the explosion notches 102. By installing the connection part 103, it is possible to easily connect the explosion-proof valve 100 to the cell top cover, and to fix the explosion-proof valve 100 to the cell top cover, thereby preventing the explosion-proof valve 100 from falling off during use of the battery and causing a safety hazard.

[0054] Accordingly, another embodiment of the present disclosure further provides a cell top cover including the explosion-proof valve of the cell top cover provided in the above embodiment. Hereinafter, the cell top cover provided in another embodiment of the present disclosure will be described in detail with reference to the drawings. For the same or corresponding parts as those in the above embodiment, reference may be made to the corresponding description in the above embodiment. There is no need to repeat the description here.

[0055] Figure 9 is a diagram showing the structure of a cell top cover in another embodiment of the present disclosure, Figure 10 is a diagram showing the top view structure of an aluminum reflective sheet of a cell top cover in another embodiment of the present disclosure, Figure 11 is a diagram showing the bottom view structure of an aluminum reflective sheet of a cell top cover in another embodiment of the present disclosure, and Figure 12 is a diagram showing the structure of another cell top cover in another embodiment of the present disclosure.

[0056] 9, the cell top cover 200 includes a pole 201 and an aluminum reflective sheet 202. The aluminum reflective sheet 202 is provided with a pole through hole 203, and the pole 201 is drilled in the pole through hole 203. The cell top cover 200 further includes the explosion-proof valve 100 of the cell top cover provided in the above embodiment.

[0057] The poles are used to electrically connect the cell to a circuit external to the cell. In some embodiments, the poles may include positive poles and negative poles. The positive poles are used to electrically connect the positive pole in the cell to a negative pole in an external circuit. The negative poles are used to electrically connect the negative pole in the cell to a positive pole in an external circuit. In some embodiments, the material of the positive pole may be aluminum. In some embodiments, the material of the negative pole may be a copper aluminum composite, a nickel aluminum composite, or the like.

[0058] The aluminum reflective sheet is used to seal the cells. The pole through holes penetrate the thickness of the aluminum reflective sheet, making it easy to drill the poles.

[0059] In some embodiments, the aluminum reflective sheet may be provided with liquid injection holes that are used to inject electrolyte into the assembled cells to cause an electrochemical reaction to occur in the electrolyte and form an electric current.

[0060] In some embodiments, the liquid injection holes can be spaced apart from the negative pole through holes and the corresponding negative poles, which can prevent the electrolyte from accidentally leaking out and adhering to the negative poles when the electrolyte is injected into the liquid injection holes, thereby at least helping to improve the safety of the battery.

[0061] In some embodiments, the aluminum reflective sheet may be provided with an explosion-proof through hole that penetrates the thickness of the aluminum reflective sheet, which is used to install an explosion-proof valve, provides an external outlet for the gas that is released after the explosion-proof valve is opened, and serves to balance the gas pressure inside and outside the cell, thereby avoiding the explosion of the cell and at least helping to improve the safety of the battery.

[0062] As shown in Figures 10 and 11, the aluminum reflective sheet 202 has a first surface 21 and a second surface 22 facing each other. As shown in Figures 1 and 2, the explosion-proof valve 100 of the cell top cover provided in the embodiment of the present disclosure has an upper surface 11 and a lower surface 12 facing each other. The explosion-proof valve 100 further includes a rupture disk 101, an explosion mark 102, and a connection part 103.

[0063] In some embodiments, the explosion-proof valve 100 of the cell top cover may be fixed to the second surface 22, where the upper surface 11 is in contact with and fixed to the lower surface 21 of the aluminum reflective sheet. When the explosion-proof valve 100 is opened, the rupture disk 101 opens from the lower surface 12 to the upper surface 11, discharging the gas inside the cell.

[0064] In some embodiments, the material of the explosion-proof valve may be aluminum or aluminum alloy. For example, the material of the explosion-proof valve may be 1060 aluminum material. The aluminum purity of 1060 aluminum material can reach up to 99.6%, and has good formability, and can withstand various pressing, pulling or bending, which is useful for industrializing the manufacture of explosion-proof valves with specific shapes. The 1060 aluminum material has good corrosion resistance, which helps to avoid the explosion-proof valve being corroded by the electrolyte in the battery and the strength of the explosion-proof valve being reduced. In addition, for example, the material of the explosion-proof valve may be a 3000 series aluminum alloy, such as 3003 aluminum alloy, 3105 aluminum alloy or 3A21 aluminum alloy. The 3000 series aluminum alloy is an aluminum-manganese alloy series, and has a large amount of manganese doping, which can effectively increase the corrosion resistance of the aluminum alloy, and can avoid the explosion-proof valve being corroded by the electrolyte and the strength of the explosion-proof valve being reduced. In addition, doping with manganese improves the welding performance of the aluminum alloy, which is useful for welding and fixing the explosion-proof valve and the battery structure, and prevents the welded parts from bursting due to the impact of pressure when the explosion-proof valve is released, helping to maintain the structural integrity of the battery.

[0065] In some embodiments, the explosion-proof valve can be formed by an extrusion molding process. Extrusion molding is a plastic processing method, in which pressure is applied to a metal blank placed in a die cavity, causing directional plastic deformation of the metal blank, and then extruding it through a die hole of an extrusion die to obtain a part or semi-finished product with a desired cross-sectional shape and dimensions as well as a certain mechanical performance. Due to the process characteristics of extrusion molding, it can be used not only to produce rod, pipe or wire products with a simple cross-sectional shape, but also to manufacture structures with complex cross-sectional shapes, which is useful for mass production of explosion-proof valve structures with complex shapes. In addition, extrusion molding products have high precision, good product surface quality, and good matching with light metals such as aluminum or light alloys such as aluminum alloys, which can reduce the product reject rate and effectively increase the material utilization rate and yield rate.

[0066] In some embodiments, the explosion-proof valve may be capsule-shaped. The capsule shape is a shape in which the middle part is a quadrilateral and two opposite sides of the quadrilateral extend as an arch, so that the whole is shaped like a capsule. Here, the straight side of the arch overlaps with the straight side of the rectangle. The symmetrical structure helps to uniform the force on the explosion-proof valve, prevent the explosion-proof valve from being accidentally opened by concentrating the stress on the explosion-proof valve in a certain area, and ensure the normal use of the explosion-proof valve. And the arch design reduces the cusp angle of the explosion-proof valve, which is beneficial for processing and production. For example, in extrusion molding, the material of the rounded workpiece is easier to flow smoothly through the die compared to the workpiece with an arch, and the stress on the corner of the workpiece is also smaller, so that the quality of the explosion-proof valve can be improved.

[0067] The rupture disk 101 is one of the components of the cell top cover explosion-proof valve 100, and is used to guide the direction of the airflow when the cell top cover explosion-proof valve 100 is opened, thereby preventing the small amount of electrolyte contained in the airflow from splashing out and preventing corrosion of the battery structure.

[0068] The rupture disk 101 includes an inner platform 104 and an outer platform 105 that is disposed around the outer periphery of the inner platform 104, and the outer platform 105 is connected to the inner platform 104, and the thickness of the inner platform 104 is greater than the thickness of the outer platform 105. This enhances the strength of the rupture disk 101, avoids the deformation of the rupture disk 101, reduces the stress of the rupture disk 101 that is subjected to the explosive mark 102, and helps to avoid the change of the explosion threshold of the explosive mark 102, thereby enhancing the safety of the battery.

[0069] In some embodiments, the thickness of the outer platform 105 is greater than the thickness of the explosion increment 102. This allows the opening location of the explosion-proof valve to be accurately controlled in the explosion increment, avoiding the problem that the opening location of the explosion-proof valve is not fixed, which is helpful in controlling the direction of the gas ejected after the explosion-proof valve is opened, and can avoid the small amount of electrolyte contained in the ejected gas from corroding the battery structure, which contributes to improving the safety of the battery.

[0070] In some embodiments, the thickness of the internal platform 104 may be equal to or less than the thickness of the connection part 103. In other embodiments, the thickness of the internal platform 104 may be greater than the thickness of the connection part 103. The thickness of the internal platform is affected by the manufacturing technology of the explosion-proof valve. For example, when the explosion-proof valve is manufactured by the extrusion integral molding technology, the material has a high plastic deformation ability, so that the material of a part of the explosion-proof valve is pressed against the internal platform, and the thickness of the internal platform is greater than the thickness of the connection part. This can increase the thickness of the rupture disk and at least increase the strength of the rupture disk, avoiding the rupture disk from being easily deformed, and improving the safety of the battery.

[0071] In some embodiments, as shown in FIG. 3, the rupture disk 101 may further include a first inclined portion 106. The first inclined portion 106 is connected between the outer platform 105 and the inner platform 104, and in the direction from the outer platform 105 to the inner platform 104, the thickness of the first inclined portion 106 gradually increases until it is equal to the thickness of the inner platform 104. The first inclined portion forms a transition between the outer platform and the inner platform, which reduces the manufacturing difficulty of the explosion-proof valve. In addition, the first inclined portion reduces the stress of the edge and corner structure of the explosion-proof valve, which avoids the edge and corner of the explosion-proof valve being damaged due to excessive stress concentration, which is helpful to improve product quality.

[0072] In some embodiments, as shown in FIG. 4, the first inclined portion 106 includes a first inclined surface 13 and a bottom surface 14 facing the first inclined surface 13, and the bottom surface 14 is a part of the lower surface 12. Here, the first inclined surface 13 connects the surface of the inner platform 104 and the surface of the outer platform 105, and the angle between the first inclined surface 13 and a normal line perpendicular to the bottom surface 14 is 60°-89°, for example, 60°, 75°, 85°, or 89°, etc. As can be understood, as long as the first inclined portion can play a role in connecting the thickness of the outer platform and the thickness of the inner platform, the angle between the first inclined surface and the normal line perpendicular to the bottom surface can be freely set according to the type of processing process of the explosion-proof valve.

[0073] In some embodiments, as shown in FIG. 5, the explosion-proof valve 100 may further include an inner recess 107. The inner recess 107 is located in the central region of the rupture disk 101, and the inner recess 107 is recessed from the upper surface 11 to the lower surface 12 of the explosion-proof valve 100, and the inner platform 104 is surrounded by the outer periphery of the inner recess 107. The process of forming the inner recess includes a press molding process, and the explosion-proof valve formed by the press and the template can be reprocessed. In the process of forming the explosion-proof valve, the occurrence of an uneven surface of the explosion-proof valve is inevitable, but the formation of the inner recess can reduce the unevenness of the explosion-proof valve surface, and obtain an explosion-proof valve with better surface quality, which can avoid the quality problem caused by uneven stress on the explosion-proof valve surface, and help improve the safety of the battery.

[0074] In some embodiments, the thickness of the inner recess 107 may be greater than the thickness of the explosion increment 102, which can avoid the explosion-proof valve opening at the inner recess without opening at the explosion increment, or the explosion-proof valve opening at the inner recess and the explosion increment simultaneously, which helps to control the opening position of the explosion-proof valve, and controls the direction of the airflow inside the battery after the explosion-proof valve is opened, and prevents a small amount of electrolyte carried away by the airflow from corroding the battery structure.

[0075] In some embodiments, the thickness of the inner recess 107 may be equal to or less than the thickness of the connecting portion 103. In other embodiments, the thickness of the inner recess 107 may be greater than the thickness of the connecting portion 103. Depending on the manufacturing process, the thickness of the inner recess can be freely set. As can be appreciated, the thickness of the inner recess formed by either manufacturing process is less than the thickness of the inner platform.

[0076] In some embodiments, as shown in FIG. 6, the rupture disk 101 may further include a second inclined portion 108. The second inclined portion 108 is connected between the inner platform 104 and the inner recess 107, and the thickness of the second inclined portion 108 gradually decreases in the direction from the inner platform 104 to the inner recess 107. The second inclined portion forms a transition between the inner recess and the inner platform, which reduces the manufacturing difficulty of the explosion-proof valve. In addition, the second inclined portion reduces the stress of the edge and corner structure of the explosion-proof valve, which avoids the edge and corner of the explosion-proof valve being damaged due to excessive stress concentration, which is helpful to improve product quality.

[0077] In some embodiments, as shown in FIG. 7, the second inclined portion 108 includes a second inclined surface 15 and a second bottom surface 16 facing the second inclined surface 15, and the second bottom surface 16 is a part of the lower surface 12. Here, the second inclined surface 15 connects the surface of the inner platform 104 and the surface of the inner recess 107, and the angle between the second inclined surface 15 and a normal line perpendicular to the second bottom surface 16 is less than 30°, and may be, for example, 30°, 28°, 15°, or 9°, etc. As can be understood, as long as the second inclined portion can play a role in connecting the thickness of the inner platform and the thickness of the inner recess, the angle between the second inclined surface and the normal line perpendicular to the second bottom surface can be freely set according to the processing process of the explosion-proof valve.

[0078] As shown in FIG. 1, the explosion notch 102 is also one of the components of the explosion-proof valve 100 of the cell top cover. The explosion notch 102 is provided around the outer periphery of the outer platform 105, and is a recess recessed from the upper surface 11 to the lower surface 12. The thickness of the explosion notch 102 is smaller than the thickness of the outer platform 105, and is the thinnest area on the explosion-proof valve 100 of the cell top cover. When an abnormality occurs in the chemical reaction inside the battery, the pressure inside the battery gradually increases and becomes greater than the pressure outside the battery. When the pressure inside the battery reaches the explosion threshold of the explosion notch, the explosion notch is torn, an opening is created in the explosion-proof valve, the gas inside the explosion-proof valve is discharged, and the pressure inside the explosion-proof valve and the pressure outside the explosion-proof valve are balanced, thereby avoiding the explosion of the battery.

[0079] In some embodiments, the thickness range of the explosion increment is 0.01 mm to 0.15 mm, and may be, for example, 0.01 mm, 0.02 mm, 0.12 mm, or 0.15 mm. By controlling the thickness of the explosion increment, the explosion threshold of the explosion increment can be controlled. This allows the explosion increment to be set to open at an appropriate pressure to avoid affecting the normal use of the battery. For example, the explosion increment is prevented from suddenly opening under normal use conditions of the battery, and electrolyte leakage is avoided. Furthermore, for example, the explosion increment is prevented from not opening even if it reaches the explosion pressure of the battery, and the explosion-proof valve is prevented from losing its explosion-proof function.

[0080] In some embodiments, the cross-sectional shape of the depression may be an inverted trapezoid with a height of 0.18 mm, a long side length of 0.3 mm, and a short side length of 0.2 mm. As can be seen, when the explosion indentations are installed, the characteristics such as different cross-sectional shapes, deployment lengths, depression depths, and depression widths can be changed according to the explosion thresholds set to adapt to different usage scenarios.

[0081] In some embodiments, the explosion-proof valve further comprises a reinforcing rib, and the thickness of the reinforcing rib is greater than the thickness of the explosion mark.The reinforcing rib is located in a part of the area of ​​the recess, and is used to strengthen the connection between the explosion mark and the external platform and the connection part, so as to avoid the explosion mark being completely torn off when the explosion-proof valve is opened, to avoid the rupture disk being separated, and to avoid the rupture disk being separated and impacting other structures inside the battery, which contributes to improving the safety of the battery.

[0082] In some embodiments, the thickness of the reinforcing rib is 0.16 mm to 0.25 mm, for example, 0.16 mm, 0.18 mm, 0.21 mm, or 0.25 mm, etc. As can be understood, the thickness of the reinforcing rib can be freely set as long as the reinforcing rib can play a role in strengthening the connection between the explosion indentation and the external platform and the connection part.

[0083] In some embodiments, the expansion length of the reinforcing rib may be 1 / 6 or less of the expansion length of the explosion indentation. This can avoid the occurrence of the problem that the tearable part of the explosion indentation is too short, which affects the gas discharge ability of the explosion-proof valve, and at least improve the explosion-proof effect of the explosion-proof valve, and thus improve the safety of the battery. As can be seen, the proportion of the expansion length of the reinforcing rib to the expansion length of the explosion indentation needs to be set in combination with the structure of the explosion indentation.

[0084] In some embodiments, the explosion-proof valve of the cell top cover may include an installation mark. The installation mark may be provided on the underside. The installation mark may also be provided adjacent to the reinforcing rib. The purpose of providing the installation mark is to improve the visibility of the installation direction of the explosion-proof valve on the cell top cover. This standardizes the installation direction of the explosion-proof valve, guides the direction of the airflow inside the cell after the explosion-proof valve is opened, and prevents the airflow from destroying the internal structure of the battery, which helps improve the safety of the battery.

[0085] In some embodiments, the shape of the attachment mark may be a letter shape. In other embodiments, the shape of the attachment mark may be a pattern. As can be appreciated, the shape of the attachment mark may be any shape as long as the attachment mark is visible.

[0086] As shown in FIG. 1, the connection part 103 is also one of the components of the explosion-proof valve 100 of the cell top cover. The connection part 103 is provided around the outer periphery of the explosion marking 102, and the connection part 103 is connected to the explosion marking 102. The role of the connection part is to facilitate the connection between the explosion-proof valve and the cell top cover. In some embodiments, the connection part and the cell top cover are welded together to fix the explosion-proof valve and the cell top cover, seal the cell, and prevent the electrolyte inside the cell from leaking.

[0087] In some embodiments, as shown in FIG. 8, the connection portion 103 includes a first outer ring portion 109 and a second outer ring portion 110. The first outer ring portion is disposed around the outer periphery of the explosion marking 102, and the first outer ring portion 109 is connected to the explosion marking 102. The first outer ring portion is used to connect the second outer ring portion and the explosion marking. The second outer ring portion 110 is disposed around the outer periphery of the first outer ring portion 109, and the second outer ring portion 110 is connected to the first outer ring portion 109. The second outer ring portion is used to provide a contact surface and facilitates the connection between the explosion-proof valve and the cell top cover. In this way, by dividing a specific area to facilitate the connection between the explosion-proof valve and the cell top cover, the standardization degree of the explosion-proof valve is increased, which helps to improve the assembly efficiency and improves the production efficiency, and also avoids quality problems caused by imperfect alignment during the assembly of the explosion-proof valve and the cell top cover, thereby contributing to improving the safety of the battery.

[0088] In some embodiments, the thickness of the first outer ring portion 109 may be equal to or less than the thickness of the second outer ring portion 110. In order to facilitate the processing of the explosion indentations, the thickness of the first outer ring portion may be smaller than the thickness of the second outer ring portion, and the thickness of the first outer ring portion is greater than the thickness of the explosion indentations. For example, when processing an explosion-proof valve in an extrusion molding process, explosion indentations with accurate dimensions cannot usually be formed, and it is necessary to perform secondary processing on the explosion-proof valve after extrusion molding, and etch explosion indentations with accurate dimensions into the explosion-proof valve. In order to facilitate the etching process, the thickness of the first outer ring portion may be smaller than the thickness of the second outer ring portion.

[0089] In some embodiments, the thickness of the first outer ring 109 is equal to or greater than the thickness of the outer platform 105. The thickness of the first outer ring may be equal to the thickness of the outer platform, which is helpful for processing the explosion notches. The thickness of the first outer ring may be greater than the thickness of the outer platform, which can avoid reducing the thickness of the explosion-proof valve, thereby making the first outer ring have a certain strength, avoiding the first outer ring being deformed during processing and / or use, and avoiding applying stress to the explosion notches, which in turn avoids changing the explosion threshold of the explosion notches, which contributes to improving the safety of the battery.

[0090] In some embodiments, the thickness range of the second outer ring portion 120 is 0.3 mm to 0.7 mm, for example, 0.3 mm, 0.4 mm, 0.5 mm, or 0.7 mm. In some embodiments, the thickness of the second outer ring portion is the same as the thickness of the substrate forming the explosion-proof valve. Since the second outer ring portion is a part that connects the explosion-proof valve and the cell top cover, the second outer ring portion needs to have a certain thickness, so as to avoid the problem of the explosion-proof valve and the cell top cover falling off due to the second outer ring portion being too thin, and to avoid affecting the safety of the battery. At the same time, the second outer ring portion should not be too thick, so as not to occupy more space than necessary for other structures in the cell top cover, which helps to avoid material waste.

[0091] In some embodiments, the ratio of the thickness of the inner platform 104 to the thickness of the second outer ring portion 110 is 0.4 to 2, for example, it may be 0.4, 0.5, 1.9 or 2. This can at least avoid the situation that the inner platform is too thick and the explosion-proof valve is difficult to adhere to the cell top cover, and also avoid the situation that the inner platform is too thin and the strength of the rupture disk is insufficient and it is easy to be deformed.

[0092] In some embodiments, as shown in FIG. 12, the cell top cover 200 may further include a protective sheet 204. The protective sheet is fixed to the first surface 21 and covers the explosion-proof through hole. The protective sheet is used to protect the explosion-proof valve, prevent the explosion-proof valve from being damaged by foreign objects, avoid the explosion-proof valve being damaged and unable to be used normally, prevent the battery from exploding, and at least help improve the safety of the battery. In addition, the protective sheet blocks a small amount of electrolyte carried away by the blowing airflow after the explosion-proof valve is opened, and prevents the electrolyte from splashing onto the negative electrode pole with the blowing airflow, causing the cell to leak electricity.

[0093] In some embodiments, the protective sheet may be made of a transparent or translucent material, which makes it easier to observe the condition of the upper surface of the explosion-proof valve, helps to timely detect damage to the explosion-proof valve and take measures, avoids safety issues caused by use when the explosion-proof valve is damaged, and helps to improve the safety of the battery.

[0094] In some embodiments, the protective sheet may be composed of a washer and a protective sheet body, the protective sheet body is fixed to the washer and covers the explosion-proof through hole, and the washer is fixed to the first surface and surrounds the outer periphery of the explosion-proof through hole, thereby setting a specific area for fixing the protective sheet and the aluminum reflective sheet, which can increase the standardization degree of the cell top cover, improve the assembly efficiency, and improve the production efficiency, and also avoid quality problems caused by imperfect alignment during the assembly of the protective sheet and the cell top cover, contributing to improving the safety of the battery.

[0095] In some embodiments, the protective sheet may further include an opening penetrating the protective sheet, the role of which is to form a passage for gas to flow, to avoid the gas inside the cell being blocked from being discharged after the explosion-proof valve is opened, and to prevent the cell from exploding due to an increase in the internal pressure.

[0096] In some embodiments, the opening is located in the edge region of the protective sheet away from the liquid inlet, so as to prevent the electrolyte remaining after the liquid is injected from the liquid inlet from entering the cavity between the protective sheet and the explosion-proof valve through the opening, and thus prevent the electrolyte from corroding the explosion-proof valve, and thus prevent the explosion-proof valve from being damaged and unable to be used normally.

[0097] In some embodiments, the distance from the end of the opening to the center of the protective sheet is smaller than the distance from the edge of the protective sheet to the center of the protective sheet, thereby controlling the direction and range of gas escaping from the opening and reducing damage to the battery structure caused by the escaping gas, which at least helps to improve the safety of the battery.

[0098] In some embodiments, the shape of the opening may be circular. In other embodiments, the shape of the opening may be square. In other embodiments, the shape of the opening may be letter-shaped. As can be seen, the role of the opening is to allow gas to flow between the cavity between the protective sheet and the explosion-proof valve and the outside environment, and the shape of the opening may vary.

[0099] In some embodiments, the width of the opening in the protective sheet is within 1 mm in the direction perpendicular to the direction from the opening to the center of the protective sheet. This can prevent the opening from being too wide and foreign matter from entering the cavity between the protective sheet and the explosion-proof valve, and can prevent the explosion-proof valve from being damaged or corroded by foreign matter, which can prevent the explosion-proof valve from being used normally, thereby improving the safety of the battery. For example, when the opening is a rectangle with a short side toward the center of the protective sheet, the length of the short side of the rectangle can be 0.2 mm, 0.5 mm, 0.7 mm, or 1 mm.

[0100] The cell top cover 200 provided in another embodiment of the present disclosure includes a pole 201 and an aluminum reflective sheet 202, the pole 201 is used to electrically connect the cell to a circuit outside the cell, and the aluminum reflective sheet 202 is used to seal the cell. The aluminum reflective sheet 202 is provided with a pole through hole 203 to facilitate drilling of the pole 201. The cell top cover 200 further includes a cell top cover explosion-proof valve 100, the explosion-proof valve 100 including a rupture disk 101, an explosion mark 102, and a connection part 103. The rupture disk 101 and the aluminum reflective sheet 202 are combined and used to seal the cell, preventing the electrolyte inside the cell from leaking. When the explosion-proof valve 100 is opened, the rupture disk 101 opens to form an opening, which allows the gas inside the cell to be discharged, and balances the gas pressure inside and outside the cell to avoid the explosion of the cell. The rupture disk 101 includes an inner platform 104 and an outer platform 105 arranged on the outer periphery of the inner platform 104, and the thickness of the inner platform 104 is greater than that of the outer platform 105. This design can increase the strength of the rupture disk 101, avoid the rupture disk 101 being deformed under force during installation and / or use, avoid the explosion threshold of the explosion serration 102 connected to the rupture disk 101 being changed, and the explosion-proof valve 100 can be used normally, which at least helps to improve the safety of the battery. The explosion serration 102 is arranged around the outer periphery of the outer platform 105 of the rupture disk, and the thickness of the explosion serration 102 is smaller than that of the outer platform 105. The explosion serration 102 is used as a weak part in the explosion-proof valve 100 to open when the pressure inside the cell exceeds the safety threshold. This allows the opening location of the explosion-proof valve 100 to be controlled, which helps to improve the safety of the battery. In addition, the explosion markings 102 are depressions recessed from the upper surface 11 to the lower surface 12 of the explosion-proof valve 100, which prevents the electrolyte inside the cell from forming crystals when reacting and prevents the explosion threshold of the explosion markings 102 from being affected. The connection part 103 is provided around the outer periphery of the explosion markings 102 and is connected to the explosion markings 102.By installing the connection part 103, it is possible to easily connect the explosion-proof valve 100 to the cell top cover, and to fix the explosion-proof valve 100 to the cell top cover, thereby preventing the explosion-proof valve 100 from falling off during use of the battery and causing a safety hazard.

[0101] Those skilled in the art will understand that the above embodiments are specific examples for realizing the present disclosure, but various changes in form and details are possible in practice without departing from the spirit and scope of the present disclosure. Since any person skilled in the art can make changes and modifications without departing from the spirit and scope of the present disclosure, the protection scope of the present disclosure should be based on the scope limited by the claims.

Claims

1. An explosion-proof valve for a cell top cover, The explosion-proof valve has opposing upper and lower surfaces, and the explosion-proof valve includes a rupture disk, an explosion indentation, and a connection portion; The rupture disk includes an inner platform and an outer platform disposed around the outer periphery of the inner platform, and the thickness of the inner platform is greater than the thickness of the outer platform; The explosion notch includes a recess on the outer periphery of the outer platform between the outer platform and the connecting portion, the thickness of the explosion notch is smaller than the thickness of the outer platform, and the recess is recessed from the upper surface of the explosion-proof valve to the lower surface of the explosion-proof valve; The connection portion is provided around the outer periphery of the explosion mark, and the connection portion is connected to the explosion mark. The explosion-proof valve on the cell top cover is characterized by:

2. The connection portion includes a first outer ring portion and a second outer ring portion, The first outer ring portion is provided around the outer periphery of the explosive notches, and the first outer ring portion is connected to the explosive notches, the second outer ring portion is provided around an outer periphery of the first outer ring portion, and the second outer ring portion is connected to the first outer ring portion; wherein a thickness of the first outer ring portion is equal to or less than a thickness of the second outer ring portion, and a thickness of the first outer ring portion is equal to or greater than a thickness of the outer platform.

2. The explosion-proof valve of claim 1, wherein the explosion-proof valve is a cell top cover.

3. The thickness range of the second outer ring portion is 0.3 mm to 0.7 mm.

3. The explosion-proof valve of claim 2.

4. the ratio of the thickness of the inner platform to the thickness of the second outer ring portion is 0.4 to 2; 3. The explosion-proof valve of claim 2.

5. The rupture disk further includes a first inclined portion; the first sloped portion is connected between the outer platform and the inner platform, and the thickness of the first sloped portion gradually increases in a direction from the outer platform toward the inner platform; 2. The explosion-proof valve of claim 1, wherein the explosion-proof valve is a cell top cover.

6. the first inclined portion includes a first inclined surface and a bottom surface facing the first inclined surface, the bottom surface being a part of the lower surface; Here, the first slope connects the surface of the internal platform and the surface of the external platform, and the angle between the first slope and a normal line perpendicular to the bottom surface is 60° to 89°.

6. The explosion-proof valve of claim 5, wherein the cell top cover is a gas-permeable ....

7. The explosion-proof valve further includes an inner recess; the internal platform is circumscribed by an outer periphery of the internal recess, the internal recess being recessed from the upper surface toward the lower surface; wherein the thickness of the inner recess is greater than the thickness of the explosion indentation; 2. The explosion-proof valve of claim 1, wherein the explosion-proof valve is a cell top cover.

8. The thickness of the inner recess is equal to or less than the thickness of the connecting portion. The explosion-proof valve of claim 7.

9. The rupture disk further includes a second inclined portion; the second sloped portion is connected between the internal platform and the internal recess, and the thickness of the second sloped portion gradually decreases in a direction from the internal platform toward the internal recess; The explosion-proof valve of claim 7.

10. The thickness range of the explosion cut is 0.01 mm to 0.15 mm.

2. The explosion-proof valve of claim 1, wherein the explosion-proof valve is a cell top cover.

11. A cell top cover, The cell top cover includes a pole and an aluminum reflective sheet, the aluminum reflective sheet is provided with a pole through hole, and the pole is drilled into the pole through hole, and the cell top cover further includes the explosion-proof valve for the cell top cover according to any one of claims 1 to 10. A cell top cover characterized by:

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