Battery casing having explosion-proof score lines, manufacturing method therefor, and secondary battery

Abstract

A battery casing having explosion-proof score lines (200), a manufacturing method therefor, and a secondary battery. The battery casing having explosion-proof score lines (200) comprises a casing (100), explosion-proof score lines (200) being formed on an outer surface and / or an inner surface of the casing (100). The explosion-proof score lines (200) comprise multiple first score lines (211), (212), (213), (214), (215), (216), (217), (218), (219), (220), (221) and (222) which are disposed at intervals, and multiple second score lines (251), (252), (253), (254), (255), (256), (257), (258), (259), (260) and (261) connected between every two adjacent first score lines (211), (212), (213), (214), (215), (216), (217), (218), (219), (220), (221) and (222). The score line residual values of each of the second score lines (251), (252), (253), (254), (255), (256), (257), (258), (259), (260) and (261) are all lower than the score line residual values of the first score lines (211), (212), (213), (214), (215), (216), (217), (218), (219), (220), (221) and (222). The tearing difficulty of each area of explosion-proof score lines (200) is adjusted by means of the second score lines (251), (252), (253), (254), (255), (256), (257), (258), (259), (260) and (261), such that the tearing difficulty of each area of explosion-proof score lines (200) is relatively similar, so that, when bursting occurs, the area outside the explosion-proof score lines (200) of the casing is prevented from being torn open into a large notch, and insufficient bursting is prevented.

Description

Battery casing with explosion-proof notches, manufacturing method thereof, and secondary battery Technical Field

[0001] The invention belongs to the technical field of secondary batteries and relates to a battery shell with explosion-proof notches, a manufacturing method thereof, and a secondary battery. Background Art

[0002] Currently, new energy vehicles and electric vehicles have become a new development trend in the automotive industry. Secondary batteries, as a power source for devices such as pure electric vehicles, plug-in hybrid vehicles, and electric bicycles, are also widely used in the new energy sector. Current secondary batteries are beginning to use lithium batteries encapsulated in thinner stainless steel casings to save material costs and reduce the battery's footprint. Laser-etched explosion-proof notches on the stainless steel casing serve as integrated explosion-proof valves, replacing those welded to the casing. This simplifies the manufacturing process for the explosion-proof structure and allows the explosion-proof structure and casing to be integrated, preventing poor welding that could compromise the explosion-proof structure's effectiveness.

[0003] Furthermore, to prevent the area enclosed by the explosion-proof notch from completely tearing during blasting and being blown away by the high pressure, potentially causing secondary damage to surrounding components, the notch is typically not a closed curve, but rather a gap. Since the gap is of normal thickness and will not tear, this ensures that the area enclosed by the explosion-proof notch remains connected to the battery housing. However, since the explosion-proof notch is typically curved, the pressure required to tear the notch can vary significantly at different locations along the curve, making it difficult to accurately adjust the overall tear pressure. Since stainless steel housings are generally thin, a low overall tear pressure will generate a significant outward impact force during blasting, causing the housing to tear wide from the gap and extend to the edges, potentially damaging adjacent battery housings. A high overall tear pressure will result in incomplete blasting at the notch, potentially leading to battery explosion and a greater risk.

[0004] Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a battery casing with explosion-proof notches, a manufacturing method thereof, and a secondary battery.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A battery casing comprises a shell having explosion-proof notches formed on its outer surface and / or inner surface; the explosion-proof notches comprise a plurality of first notches arranged at intervals and a plurality of second notches connected between every two adjacent first notches, wherein the residual value of each second notch is smaller than the residual value of the first notches.

[0008] A method for manufacturing a battery casing with explosion-proof notches, for manufacturing a battery casing with explosion-proof notches, comprising the following steps:

[0009] S101, take a shell;

[0010] S102, etching a plurality of first notches distributed at intervals on the outer surface and / or inner surface of the housing;

[0011] S103, etching a second notch between every two adjacent first notches, connecting the plurality of first notches into a whole through the second notches, thereby forming an explosion-proof notch, wherein the residual value of the second notch is smaller than the residual value of the first notch.

[0012] A method for manufacturing a battery casing with explosion-proof notches, for manufacturing a battery casing with explosion-proof notches, comprising the following steps:

[0013] S201, take a shell;

[0014] S202, etching a first continuous line-shaped scratch on the outer surface and / or inner surface of the housing;

[0015] S203 , etching the first notch at intervals along its length direction to form a plurality of second notches overlapping therewith, thereby forming explosion-proof notches, wherein the residual values ​​of the second notches are all smaller than the residual value of the first notches.

[0016] In the present invention, by arranging multiple first and second score lines in a shape similar to a dotted line, the first score increases the barrier effect during explosion, preventing the explosion energy from being fully absorbed by the explosion-proof score, which could result in larger tears in other parts of the battery housing and damage to adjacent battery housings. By selecting the position, number, score residual value, and length of the second score, the tearing difficulty of areas with small curvatures can be selectively reduced, making the tearing difficulty of each area of ​​the explosion-proof score more similar, thus avoiding incomplete explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0018] 1 and 2 are schematic structural diagrams of an embodiment of a battery housing with explosion-proof notches according to the present invention.

[0019] FIG3 is a schematic cross-sectional view of an explosion-proof notch.

[0020] FIG4 is a schematic diagram of the overall structure of the explosion-proof notch.

[0021] FIG5 is a schematic structural diagram of the first notch and the second notch.

[0022] FIG6a, FIG6b, FIG6c, FIG6d and FIG6e are schematic structural diagrams of several explosion-proof notches of different shapes used in the blasting test.

[0023] FIG. 7 a is a schematic diagram showing a notch formed after the explosion-proof notch in FIG. 6 a is torn.

[0024] FIG7 b is a schematic diagram showing a notch formed after the explosion-proof notch in FIG5 is torn.

[0025] FIG8 is a flow chart of an embodiment of a method for manufacturing a battery casing with explosion-proof notches according to the present invention.

[0026] FIG9 is a schematic structural diagram of the first notch formed.

[0027] FIG. 10 is a flow chart of another embodiment of a method for manufacturing a battery casing having explosion-proof notches according to the present invention.

[0028] The meanings of the numbers in the accompanying drawings are: shell-100; wide side-101; narrow side-102; top cover-111; bottom cover-112; explosion-proof notch-200; first curved notch-201; second curved notch-202; connecting notch-203; notch-204; notch-205, 206; small curvature area-207; large curvature area-208; first notch-211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222; second notch-251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261. DETAILED DESCRIPTION

[0029] The following describes the implementation of the present invention through specific examples. The illustrations provided in the following embodiments are only used to schematically illustrate the basic concept of the present invention. The following embodiments and features in the embodiments may be combined with each other unless there is any conflict.

[0030] Example 1

[0031] The present invention discloses a battery casing. Figures 1 and 2 illustrate schematic structural diagrams of an embodiment of a battery casing with explosion-proof notches. The battery casing with explosion-proof notches in this embodiment includes a housing 100 , with explosion-proof notches 200 etched onto the outer and / or inner surfaces of the housing 100 . These notches 200 form an integrated explosion-proof valve structure.

[0032] The housing 100 is preferably made of stainless steel, generally with a wall thickness within the range of 0.15mm to 0.3mm. In this embodiment, the wall thickness of the stainless steel housing 100 is 0.18mm±0.005mm. Of course, the housing 100 may also be made of an aluminum alloy. When using an aluminum alloy, the wall thickness of the housing 100 will be much greater than when using stainless steel.

[0033] The housing 100 is generally a rectangular parallelepiped in the shape of a thin sheet, including a top cover 111, a bottom cover 112 opposite the top cover 111, two oppositely disposed wide sides 101, and two oppositely disposed narrow sides 102. A housing 100 of this shape can be used to produce blade batteries, square batteries, and the like. Since the two wide sides 101 will fit tightly against the adjacent batteries on either side during installation, thereby preventing the explosion-proof notch 200 from being torn, the explosion-proof notch 200 is generally not provided on the two wide sides 101 of the housing 100. In addition, since components such as electrodes are provided on the top cover 111 of the housing 100, there is less area available for etching to form the explosion-proof notch 200, and generally, the explosion-proof notch 200 is avoided on the top cover 111. Therefore, the explosion-proof notch 200 is generally etched on one of the narrow sides 102 of the housing 100 or on the bottom cover 112 of the housing 100.

[0034] When the battery cells inside the battery are damaged and release a large amount of heat and / or gas, the pressure inside the housing 100 increases rapidly. If the housing 100 is provided with an explosion-proof notch 200, and the air pressure inside the housing 100 is too high, the explosion-proof notch 200 will tear open under the action of the high pressure as the air pressure increases, allowing the high-pressure gas inside the housing 100 to escape from the torn portion. This quickly reduces the air pressure inside the housing 100, prevents battery explosion, and ensures the personal safety of the manufacturer and user. The air pressure value at which the explosion-proof notch 200 is completely torn is the overall tearing pressure value of the explosion-proof notch 200.

[0035] The explosion-proof notch 200 includes a plurality of first notches arranged at intervals and a plurality of second notches connected between every two adjacent first notches, so that each second notch forms a shape similar to a dotted line. Of course, when the head end and / or tail end of the explosion-proof notch 200 is a second notch, the second notch at the head end or tail end is only connected to one adjacent first notch. The notch residual values ​​of each first notch can generally be the same; the notch residual values ​​of each second notch can be the same or different, but the notch residual values ​​of each second notch are all smaller than the notch residual values ​​of the first notch. The notch residual value of the first notch is generally in the range of 0.10mm to 0.15mm; the notch residual value of the second notch is generally in the range of 0.03mm to 0.09mm.

[0036] Referring to FIG3 , the explosion-proof notch 200 (i.e., the first notch and the second notch) is generally a groove structure with a wide top and narrow bottom cross-section. In this embodiment, the cross-sections of the first notch and the second notch are both trapezoidal, wide top and narrow bottom. The overall tear pressure value of the explosion-proof notch 200 is affected by multiple factors, the main influencing factors including the notch residual value t of the explosion-proof notch 200, the bottom width W of the explosion-proof notch 200 cross-section, the angle a between the waist of the trapezoidal cross-section and the vertical direction (i.e., the height of the trapezoid), the shape of the explosion-proof notch 200, the wall thickness T of the shell 100, and the material of the shell 100. The notch residual value of the explosion-proof notch 200 is defined as the remaining thickness of the shell 100 after thinning at the explosion-proof notch 200.

[0037] If the residual value t of the explosion-proof notch 200 is small, the overall tearing pressure value of the explosion-proof notch 200 is small; when the explosion-proof notch 200 explodes due to battery cell damage, the blocking force at the explosion-proof notch 200 is small, which can easily lead to the explosion of the explosion-proof notch 200. The enclosed part of the explosion-proof notch 200 will tear other parts of the shell 100 into a large gap under the huge impact force after the explosion-proof notch 200 is completely exploded, thereby causing damage to the adjacent battery shell 100. If the residual value t is large, when the internal pressure of the battery reaches the upper limit pressure, the explosion-proof notch 200 may not be completely torn open; as a result, the pressure relief port formed at the explosion-proof notch 200 is relatively small, and the gas inside the battery cannot be discharged in time, which may cause the battery to over-swell and cause an explosion. However, since there are many factors that affect the overall tearing pressure value of the explosion-proof notch 200, when the residual values ​​of the notches at various locations on the explosion-proof notch 200 are the same, or when the residual values ​​of the notches at various locations in several large component areas of the explosion-proof notch 200 are the same, it is difficult to reduce the influence of other factors on the overall tearing pressure value of the explosion-proof notch 200, thereby ensuring that the explosion-proof notch 200 can be completely torn open without causing large gaps in other parts of the shell 100.

[0038] In this embodiment, by providing a first score and a second score with different score residual values, the overall tearing difficulty of the explosion-proof score 200 can be increased by increasing the score residual value at the first score, and then the tearing difficulty of the explosion-proof score 200 can be adjusted by providing the second score. By selecting the position, number, score residual value, and length of the second score, the tearing difficulty of the explosion-proof score 200 can be adjusted, making the adjustment of the tearing difficulty of the explosion-proof score 200 more convenient and precise, thereby selectively reducing the tearing difficulty in various areas of the explosion-proof score 200. For example, a longer second score can be provided in an area of ​​the explosion-proof score 200 where the tearing difficulty is greater, and the score residual value of the second score in this area can be appropriately reduced. This can significantly reduce the tearing difficulty in previously difficult-to-tear areas of the explosion-proof score 200, resulting in a more similar tearing difficulty across various areas of the explosion-proof score 200 after adjustment. This facilitates controlling the overall tearing pressure of the explosion-proof notch 200 so that the overall tearing pressure satisfies the requirement of completely tearing the explosion-proof notch 200 without tearing other parts of the shell 100 into larger gaps.

[0039] The lower base width W of the cross-section of the first and second notches can be the same, generally 0.03 mm to 0.1 mm. In this embodiment, the lower base width W of the cross-section of the first and second notches is 0.08 mm. The angle a between the waist and the height of the trapezoidal cross-section of the first and second notches is generally within the range of 25° to 45°.

[0040] Because, under the same conditions, areas with smaller radiuses of curvature of the explosion-proof notch 200 curve are more difficult to tear, the curvature radius of each area of ​​the explosion-proof notch 200 can be used to determine whether the area is easy to tear, thereby roughly determining the length of the second notch. For example, a first curvature radius threshold and a second curvature radius threshold can be pre-set, with the first curvature radius threshold being greater than the second curvature radius threshold. The first curvature radius threshold is generally greater than the width of the narrow side 102 of the housing 100 or the bottom cover 112 where the explosion-proof notch 200 is located (i.e., the length along the y-axis in FIG. 1 or FIG. 2 ), and the second curvature radius threshold is generally less than half the width of the narrow side 102 of the housing 100 or the bottom cover 112 where the explosion-proof notch 200 is located.

[0041] The shape of the explosion-proof score 200 includes a curve with a curvature radius less than a second curvature radius threshold, and a curve or straight line segment with a curvature radius greater than a first curvature radius threshold. The straight line segment region or the curve region with a curvature radius greater than the first curvature radius threshold in the explosion-proof score 200 is a large curvature region 208, i.e., an easily tearable region (an area with low tearing difficulty). The curve region with a curvature radius less than the second curvature radius threshold in the explosion-proof score 200 is a small curvature region 207, i.e., an area that is not easily tearable (an area with high tearing difficulty). When configuring the second score, the maximum length of the second score in the large curvature region 208 (i.e., the longest second score in that region) can be greater than the maximum length of the second score in the small curvature region 207, thereby further reducing the tearing difficulty in the area that is not easily tearable. Alternatively, the score residual value of the second score in the large curvature region 208 can be smaller than the score residual value of the second score in the small curvature region 207, similarly reducing the tearing difficulty in the area that is not easily tearable. Of course, the maximum length of the second notch in the large curvature region 208 can also be greater than the maximum length of the second notch in the small curvature region 207, and the notch residual value of the second notch in the large curvature region 208 can be less than the notch residual value of the second notch in the small curvature region 207.

[0042] The overall shape of the explosion-proof notch 200 can be a combination of one or more of a circular arc, an elliptical arc, a spline curve, and a straight line segment, and the head and tail ends of the explosion-proof notch 200 are not connected. Because the shape of the explosion-proof notch 200 is a closed curve, when the battery cell heats up and the gas inside the shell 100 expands, causing the explosion-proof notch 200 to tear, the area enclosed by the explosion-proof notch 200 will often be torn as a whole and blown away by high pressure, which can easily cause secondary damage to other battery cells or the water cooling plate and surrounding connected circuits. Therefore, the explosion-proof notch 200 adopts a non-closed shape with a non-connected head and tail, which can prevent secondary damage to the battery when the battery cell heats up.

[0043] For example, the explosion-proof notch 200 may include a symmetrically arranged first curved notch 201 and a second curved notch 202, and a connecting notch 203 connecting the first curved notch 201 and the second curved notch 202. The first curved notch 201 and the second curved notch 202 are not connected, thereby forming a gap 204 between the first curved notch 201 and the second curved notch 202. The first curved notch 201 and the second curved notch 202 are shaped like curves with a maximum curvature radius less than a second curvature radius threshold (i.e., the first curved notch 201 and the second curved notch 202 are located at a large curvature region 208). The connecting notch 203 is shaped like a straight line segment or a curve with a minimum curvature radius greater than the first curvature radius threshold (i.e., the connecting notch 203 is located at a small curvature region 207). The first curved notch 201 and the second curved notch 202 are generally shaped like circular arcs, elliptical arcs, or planar spirals, and the angles of the first curved notch 201 and the second curved notch 202 are generally in the range of 180° to 270°. The shape of the connecting notch 203 is generally a straight line segment, an arc with a radius greater than a first curvature radius threshold, or an elliptical arc with a minimum curvature radius greater than the first curvature radius threshold.

[0044] Referring to Figures 4 and 5 , in this embodiment, the explosion-proof notch 200 is provided on the bottom cover 112 of the housing 100, and the width of the bottom cover 112 is 32 mm. The connecting notch 203 is a straight line segment, while the first curved notch 201 and the second curved notch 202 are circular arcs with a diameter of 15 mm and an angle of 240° (i.e., a semicircular arc with an additional 60° angle). In the region of the first curved score 201, a first score 211, a second score 251, a first score 212, a second score 252, a first score 213, a second score 253, a first score 214, a second score 254, a first score 215, a second score 255, a first score 216, and a second score 256 are arranged at intervals. In the region of the connecting score 203, a first score 217, a second score 257, a first score 218, a second score 258, a first score 219, a second score 259, a first score 220, and a second score 260 are arranged at intervals. In the region of the second curved score 202, a first score 221, a second score 261, and a first score 222 are arranged at intervals. The score residual value of each of the first scores is 0.13 mm, and the score residual value of each of the second scores is approximately 0.08 mm. By setting the angle of the first curved score 201 and the second curved score 202 to be greater than 180°, the leading end and the trailing end of the explosion-proof score 200 (i.e., the end of the first curved score 201 where the first score 211 is set and the end of the second curved score 202 where the first score 222 is set) are concave inward, so that when the explosion-proof score 200 explodes, part of the impact force can be converted into an inward tearing force, thereby offsetting part of the outward tearing force and reducing the size of the gap formed by the tearing.

[0045] The explosion-proof notches 200 are generally formed by laser etching. The first notches and the second notches can be formed separately by two or multiple laser etchings. For example, a first laser etching can be performed to form a total of 12 first notches, namely, first notches 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, and 222. Then, a second laser etching process is performed to form 11 second notches, namely, second notches 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, and 261, between the 12 first notches. This connects the 12 first notches and the 11 second notches to form a single entity. The shape of the explosion-proof notch 200 formed after two laser etching steps is shown in FIG5 . Of course, if the residual values ​​of the second notches are inconsistent, the number of laser etching steps can be increased. It should be noted that the thicker lines of the second notches in FIG5 are only for easier identification of the first and second notches and do not represent the actual cross-sectional widths of the first and second notches.

[0046] Among them, the lengths of second scores 257, second scores 258, second scores 259, and second scores 260 located in the connecting score 203 region, which is relatively easy to tear, are relatively short and substantially similar. In the first curved score 201 and second curved score 202 regions, which are not easily to tear, the longest second scores are second scores 254 and second scores 261, respectively. The lengths of second scores 254 and second scores 261 are much longer than those of second scores 257, second scores 258, second scores 259, and second scores 260. In other words, second scores 254 and second scores 261 are easier to tear. As a result, the difficulty of tearing in the first curved score 201 and second curved score 202 regions is reduced more significantly after the second scores are provided than in the connecting score 203 region.

[0047] Please refer to Figures 6a, 6b, 6c, 6d, and 6e, which respectively illustrate several different shaped explosion-proof notches 200 used in the blasting tests conducted in this application. During the blasting process, the explosion-proof notches 200 in Figures 6a, 6b, and 6c each tore a large notch 205 in the shell 100 extending to the junction of the shell 100's side surfaces. Please refer to Figure 7a, which is a schematic diagram of the notch 205 formed after the explosion-proof notch 200 in Figure 6a was torn. The dotted line in the figure represents the tearing path. Due to the significant differences in tearing difficulty in different areas of the explosion-proof notches 200 in Figures 6d and 6e, the explosion-proof notches 200 experienced insufficient blasting (i.e., the explosion-proof notches 200 failed to fully explode). When the explosion test was conducted using the explosion-proof notch 200 of this embodiment (i.e., the explosion-proof notch 200 in FIG. 5 ), the explosion-proof notch 200 was able to completely explode each time, and the notch 206 formed in the area of ​​the housing 100 outside the explosion-proof notch 200 was very small. Please refer to FIG. 7 b , which is a schematic diagram of the notch 206 formed after the explosion-proof notch 200 in FIG. 5 was torn (the dotted line in the figure indicates the tear path); FIG. 7 b shows that the notch 206 is still a considerable distance from the junction of the side surfaces of the housing 100, and will not cause damage to the adjacent battery housing 100.

[0048] In this embodiment, 12 first notches and 11 second notches are arranged in a shape similar to a dotted line and sequentially connected to form the explosion-proof notch 200. Since the first notches have a larger residual value, the first notches can enhance the barrier effect during explosion, preventing the explosion energy from being fully absorbed after the explosion at the explosion-proof notch 200, resulting in larger tears in other parts of the housing 100 and damage to adjacent battery housings 100. Since the second notches have a smaller residual value, the position, number, residual value, and length of the second notches can be selected to selectively reduce the tearing difficulty of the explosion-proof notch 200 in the small curvature region 207, making the tearing difficulty of each area of ​​the explosion-proof notch 200 relatively similar, thereby avoiding the occurrence of insufficient blasting.

[0049] Example 2

[0050] The battery case with explosion-proof notches in this embodiment differs from that in Example 1 only in that the explosion-proof notches 200 in this embodiment include a first continuous linear notch and a plurality of second notches spaced and overlapping along the length of the first notch in the form of dotted lines; that is, the overall shape of the first notch is the same as that of the explosion-proof notch 200, and each second notch is formed by further reducing the residual value of the notch in a portion of the first notch. The method for forming the explosion-proof notches 200 in this embodiment is as follows:

[0051] First, a first laser etching is performed according to the shape and residual value of the first notch to obtain the first notch. In this embodiment, the etching depth of each first notch obtained by the first laser etching is 0.05 mm. After the first laser etching is completed, the shape of the first notch formed is shown in FIG4 .

[0052] Then, a second laser etching is performed on the first notch according to the position and residual value of each second notch to form each second notch. The second laser etching generally continues to etch downward by 0.05 mm on the basis of the first laser etching, that is, the total etching depth at the position of the second notch after two laser etchings is about 0.10 mm. Please refer to Figure 5. The second laser etching forms a total of 11 second notches, namely, second notch 251, second notch 252, second notch 253, second notch 254, second notch 255, second notch 256, second notch 257, second notch 258, second notch 259, second notch 260, and second notch 261. In this embodiment, since the first notch is formed by laser etching along a continuous path, the control process of laser etching when forming the first notch is simplified.

[0053] Example 3

[0054] The present invention also discloses a method for manufacturing a battery casing with explosion-proof notches. Please refer to FIG8 , which is a flow chart of an embodiment of the method for manufacturing a battery casing with explosion-proof notches according to the present invention. The method for manufacturing a battery casing with explosion-proof notches according to this embodiment includes the following steps:

[0055] S101. Take a housing 100. Continuing with Figures 1 and 2, the housing 100 is generally a thin, rectangular parallelepiped, comprising a top cover 111, a bottom cover 112 opposite the top cover 111, two opposing wide side surfaces 101, and two opposing narrow side surfaces 102. This shape of housing 100 can be used in the production of batteries such as blade batteries and prismatic batteries.

[0056] S102. Referring to FIG. 9 , a plurality of first notches are etched on the outer surface and / or inner surface of the housing 100 to form a plurality of spaced apart first notches. The residual values ​​of the plurality of first notches can be the same, so that all first notches can be formed by a single etching operation; the residual values ​​of the first notches are generally within a range of 0.10 mm to 0.15 mm. The explosion-proof notches 200 (i.e., the first notches and the second notches) are generally groove structures with a cross-section that is wide at the top and narrow at the bottom. In this embodiment, the cross-sections of the first notches and the second notches are both trapezoidal, with a wide top and narrow bottom.

[0057] S103. Continuing with FIG. 5 , a second notch is etched between each two adjacent first notches, so that each second notch forms a shape similar to a dotted line. Of course, when the leading and / or trailing ends of the explosion-proof notch 200 are second notches, the second notch at the leading or trailing end is connected only to one adjacent first notch. The second notches connect the plurality of first notches spaced apart at intervals into a single entity, thereby forming the explosion-proof notch 200. The residual values ​​of the second notches are all less than those of the first notches.

[0058] Because, under the same conditions, areas with smaller radiuses of curvature of the explosion-proof notch 200 curve are more difficult to tear, the curvature radius of each area of ​​the explosion-proof notch 200 can be used to determine whether the area is easy to tear, thereby roughly determining the length of the second notch. For example, a first curvature radius threshold and a second curvature radius threshold can be pre-set, with the first curvature radius threshold being greater than the second curvature radius threshold. The first curvature radius threshold is generally greater than the width of the narrow side 102 of the housing 100 or the bottom cover 112 where the explosion-proof notch 200 is located (i.e., the length along the y-axis in FIG. 1 or FIG. 2 ), and the second curvature radius threshold is generally less than half the width of the narrow side 102 of the housing 100 or the bottom cover 112 where the explosion-proof notch 200 is located.

[0059] Example 4

[0060] Please refer to Figure 10, which is a flow chart of another embodiment of the method for manufacturing a battery casing with explosion-proof notches according to the present invention. The method for manufacturing a battery casing with explosion-proof notches according to this embodiment includes the following steps:

[0061] S201: Take a housing 100. The shape and material of the housing 100 can be the same as those of the housing 100 in Example 3.

[0062] S202: Form a continuous linear first score on the outer surface and / or inner surface of the housing 100 by a single laser etching operation; the shape of the first score formed is shown in FIG4 . The etching depth of each first score is 0.05 mm, i.e., the etching residual value of each first score is 0.13 mm.

[0063] S203: Multiple second notches are formed along the length of the first notch by one or more laser etching steps, overlapping the first notch, to form explosion-proof notches 200. The residual values ​​of the second notches are all less than the residual values ​​of the first notch. In this embodiment, a total of 11 second notches are formed by the second laser etching, namely, second notches 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, and 261. During laser etching in this step, the laser etching is generally continued downward by 0.05 mm based on the first laser etching. That is, the total etching depth at the location of the second notch after two laser etchings is generally about 0.10 mm, and the etching residual value is about 0.08 mm.

[0064] The only difference between this embodiment and Example 1 is that the explosion-proof scoring 200 of this embodiment includes a first scoring line in the form of a continuous line and a plurality of second scoring lines spaced and overlapping along the length of the first scoring line. Specifically, the overall shape of the first scoring line is identical to that of the explosion-proof scoring 200, but each second scoring line is formed by further reducing the scoring residual value in a portion of the first scoring line. In this embodiment, since the first scoring line is formed by laser etching along a continuous path, the laser etching control process for forming the first scoring line is simplified.

[0065] The present invention also discloses a secondary battery, which can be a power battery or an energy storage battery. The housing of the secondary battery can adopt a battery housing according to any of the above-mentioned embodiments. Of course, the secondary battery also includes a cell housed within the battery housing and other structures required for conventional secondary batteries. These are all prior art and will not be described in detail here.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A battery housing with explosion-proof indentations, characterized in that: It includes a housing, and explosion-proof indentations are formed on the outer surface and / or inner surface of the housing; the explosion-proof indentations include a plurality of first indentations arranged at intervals and a plurality of second indentations connected between every two adjacent first indentations, and the indentation residues of each of the second indentations are less than the indentation residues of the first indentations.

2. The battery case with explosion-proof indentations according to claim 1, characterized in that: The shape of the explosion-proof indentations is one or a combination of an arc, an elliptical arc, a spline curve, and a straight line segment, and the head and tail ends of the explosion-proof indentations are not connected.

3. The battery case with explosion-proof indentations according to claim 2, wherein: A first curvature radius threshold and a second curvature radius threshold are preset, and the first curvature radius threshold is greater than the second curvature radius threshold; the shape of the explosion-proof indentations includes a curve with a curvature radius less than the second curvature radius threshold and a curve or a straight line segment with a curvature radius greater than the first curvature radius threshold. The straight line segment area or the curve area with a curvature radius greater than the first curvature radius threshold in the explosion-proof indentations is a large curvature area, and the curve area with a curvature radius less than the second curvature radius threshold in the explosion-proof indentations is a small curvature area.

4. The battery case with explosion-proof indentations according to claim 3, characterized in that: The maximum length of the second indentations in the large curvature area is greater than the maximum length of the second indentations in the small curvature area.

5. The battery housing with explosion-proof indentations according to claim 3, characterized in that: The indentation residues of the second indentations in the large curvature area are less than the indentation residues of the second indentations in the small curvature area.

6. The battery housing with explosion-proof indentations according to claim 3, characterized in that: The explosion-proof indentations include a first curve indentation, a second curve indentation, and a connecting indentation connecting the first curve indentation and the second curve indentation. The first curve indentation and the second curve indentation are not connected, so as to form a notch between the first curve indentation and the second curve indentation; the shapes of the first curve indentation and the second curve indentation are curves with a maximum curvature radius less than the second curvature radius threshold, and the shape of the connecting indentation is a straight line segment or a curve with a minimum curvature radius greater than the first curvature radius threshold.

7. The battery housing with explosion-proof indentations according to claim 6, characterized in that: The shapes of the first curve indentation and the second curve indentation are an arc, an elliptical arc, or a planar spiral, and the angular range of the first curve indentation and the second curve indentation is 180° to 270°; the shape of the connecting indentation is a straight line segment, an arc with a radius greater than the first curvature radius threshold, or an elliptical arc with a minimum curvature radius greater than the first curvature radius threshold.

8. The battery case with explosion-proof indentations according to claim 1, characterized in that: The housing is made of stainless steel material with a thickness of 0.15 mm to 0.3 mm, the indentation residue of the first indentations is 0.10 mm to 0.15 mm; the indentation residue of the second indentations is 0.03 mm to 0.09 mm.

9. The battery housing with explosion-proof indentations according to claim 8, characterized in that: Both the first indentations and the second indentations are groove structures with a wider upper part and a narrower lower part in cross section, and the width of the lower bottom of the cross section is 0.03 mm to 0.1 mm.

10. A manufacturing method of a battery case with explosion-proof indentations, which is used to manufacture the battery case with explosion-proof indentations as described in any one of claims 1 to 9, characterized in that, It includes the following steps: S101. Take a housing. S102. Etch a plurality of first indentations distributed at intervals on the outer surface and / or inner surface of the housing. S103. Respectively etch a second indentation between every two adjacent first indentations, and connect the plurality of first indentations into a whole through each second indentation, so as to form explosion-proof indentations, and the indentation residues of the second indentations are all less than the indentation residues of the first indentations.

11. A manufacturing method of a battery case with explosion-proof indentations, used for manufacturing the battery case with explosion-proof indentations as described in any one of claims 1 to 9, characterized in that, It includes the following steps: S201. Take a housing. S202. Etch continuous linear first indentations on the outer surface and / or inner surface of the housing. S203. Etch at intervals along the length direction of the first notch to form a plurality of second notches overlapping thereon, thereby forming explosion-proof notches, and the notch residues of the second notches are all smaller than the notch residue of the first notch.

12. A secondary battery, characterized in that: Comprising a battery case with explosion-proof notches according to any one of claims 1 to 9.

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