Manufacturing method of battery shell with anti-explosion nicks, battery and electric equipment

Abstract

The invention relates to a manufacturing method of a battery shell with anti-explosion nicks, a battery and electric equipment. The manufacturing method of the battery shell comprises the following steps: taking the battery shell; a laser etching path is determined according to the pattern of the anti-explosion nick, the anti-explosion nick comprises a first linear nick and a second linear nick, and the first linear nick and the second linear nick intersect at one point; the first linear nick, the second linear nick and the nick depth at the intersection point of the first linear nick and the second linear nick are the same; the explosion-proof nick further comprises at least one arc nick, the circle center of the arc nick is the intersection point of the first linear nick and the second linear nick, and the two ends of the arc nick intersect with the first linear nick and the second linear nick respectively. Adjusting laser etching parameters according to the material and the thickness of the battery shell; an anti-explosion nick is etched on the battery shell through laser according to the etching path; and carrying out post-treatment on the etched battery shell.

Description

Technical Field

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

[0002] At present, new energy vehicles and electric vehicles have become a new development trend in the automotive industry; and secondary batteries, as the power source of pure electric vehicles, plug-in hybrid vehicles and electric bicycles, are also widely used in the field of new energy. At present, most secondary batteries use lithium batteries encapsulated in aluminum shells. Generally, a pressure relief hole is set on the top cover of the battery, and an explosion-proof valve is welded at the pressure relief hole to release the internal pressure when the internal pressure of the battery is large, so as to prevent safety accidents such as battery explosion. However, when the pressure in the battery changes and the pressure is too high, if the stability of the explosion-proof valve welded on the top cover is not enough, it is easy to cause the entire explosion-proof valve to be flushed open during pressure relief, thereby destroying the safety of the battery and the entire battery system. In addition, the traditional method requires opening a hole in the top cover and making a separate explosion-proof valve, and requires high-precision laser welding equipment. The welding requires sealing and cannot burn through the thinner explosion-proof valve, and the explosion-proof valve also needs to be stamped separately. The material of the explosion-proof valve still relies on imports, which is costly and not conducive to the integrity of the battery shell. Summary of the invention

[0003] 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 method for manufacturing a battery casing with explosion-proof notches, a battery and an electrical device.

[0004] To achieve the above object, the present invention provides a technical solution: a method for manufacturing a battery casing with explosion-proof notches, comprising the following steps:

[0005] S100, taking a battery casing;

[0006] S200, determining a laser etching path according to a pattern of explosion-proof notches, wherein the explosion-proof notches include a first linear notch and a second linear notch, the first linear notch and the second linear notch intersect at one point, and the notch depths of the first linear notch, the second linear notch and the intersection of the first linear notch and the second linear notch are the same; the explosion-proof notches also include at least one arc notch, the center of the arc notch is the intersection of the first linear notch and the second linear notch, and both ends of the arc notch intersect with the first linear notch and the second linear notch respectively;

[0007] When determining the laser etching path, the first linear score is divided into two segments at the intersection of the first linear score and the second linear score, thereby forming a laser etching path including three non-intersecting line segments together with the second linear score; or

[0008] When determining the laser etching path, the second linear score is divided into two segments at the intersection of the first linear score and the second linear score, thereby forming a laser etching path including three mutually non-intersecting line segments together with the first linear score.

[0009] S300, adjusting laser etching parameters according to the material and thickness of the battery shell;

[0010] S400, etching an explosion-proof notch on the battery housing according to an etching path by laser; the explosion-proof notch is a groove structure with a wide upper portion and a narrow lower portion in cross section;

[0011] S500, post-processing the etched battery shell.

[0012] Furthermore, the battery shell is made of iron-based alloy material, nickel-based alloy material, titanium alloy material or aluminum alloy material.

[0013] Furthermore, the battery shell is made of stainless steel, the thickness of the stainless steel is 0.05mm-0.8mm; the residual value of the explosion-proof notch is 0.01mm-0.3mm, wherein the residual value of the notch is defined as the remaining thickness of the battery shell after thinning at the explosion-proof notch; or

[0014] The battery shell is made of aluminum alloy material, the thickness of the aluminum alloy material is 0.2mm-1.5mm, and the residual value of the explosion-proof notch is 0.05mm-0.5mm, wherein the residual value of the notch is defined as the remaining thickness of the battery shell after thinning at the explosion-proof notch.

[0015] Furthermore, when the shell is made of stainless steel, the residual value of the explosion-proof notch is 0.01 mm to 0.08 mm; when the shell is made of aluminum alloy, the residual value of the explosion-proof notch is 0.05 mm to 0.2 mm.

[0016] Furthermore, the cross-sectional shape of the explosion-proof notch is a trapezoid, "V" shape or "U" shape that is wide at the top and narrow at the bottom, and the angle between the side of the cross-sectional shape and the vertical direction is 5° to 60°; the bottom width of the cross-sectional area of ​​the explosion-proof notch is 0 to 0.5 mm.

[0017] Furthermore, the angle between the side of the cross-sectional shape and the vertical direction is 25° to 45°; and the bottom width of the cross-sectional area of ​​the explosion-proof notch is 0.03 mm to 0.1 mm.

[0018] To achieve the above object, another technical solution provided by the present invention is: a secondary battery, comprising a battery casing manufactured by the manufacturing method of the battery casing with explosion-proof notches described above.

[0019] In order to achieve the above object, another technical solution provided by the present invention is: an electrical device, comprising the secondary battery described above.

[0020] In the present invention, a groove structure with a cross section that is wide at the top and narrow at the bottom is formed by laser etching as an explosion-proof notch, and the formed explosion-proof notch has a higher precision. When etching the explosion-proof notch, the tearing air pressure value at the explosion-proof notch can be adjusted by adjusting the bottom width of the groove structure and the angle between the side of the groove structure cross section and the vertical direction, and it is more convenient to adjust the tearing air pressure value at the explosion-proof notch. In the present invention, by setting two arc notches, when the air pressure inside the shell is too high to tear the explosion-proof notch, the two fan-shaped areas formed by the two arc notches and the first straight line notch and the second straight line notch will completely roll outward during the tearing process, thereby greatly increasing the opening area formed when the explosion-proof notch is torn, so that the high-pressure gas inside the battery shell can be quickly discharged. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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 on the present application. In the drawings:

[0022] Figure 1 The present invention is a flow chart of a method for manufacturing a battery casing with explosion-proof notches according to an embodiment of the present invention.

[0023] Figure 2 and Figure 3 It is a schematic diagram of the structure of a battery shell with a runway-shaped explosion-proof notch.

[0024] Figure 4 It is a structural schematic diagram of a circular explosion-proof notch with a notch.

[0025] Figure 5 It is a structural schematic diagram of an elliptical explosion-proof notch with a notch.

[0026] Figure 6 It is a structural schematic diagram of a runway-shaped explosion-proof notch with a notch.

[0027] Figure 7 It is a schematic diagram of the structure of a battery shell with a cross-shaped explosion-proof notch.

[0028] Figure 8 It is a structural schematic diagram of the cross-shaped explosion-proof notch.

[0029] Fig. 9 This is a schematic diagram of the structure after adding two arc notches on the cross-shaped explosion-proof notch.

[0030] Fig.10 Schematic diagram of the cross section of the explosion-proof notch.

[0031] The meanings of the symbols in the accompanying drawings are:

[0032] Shell-100; top surface-111; bottom surface-112; wide side surface-121; narrow side surface-131; explosion-proof notch-200; notch-201; semi-circular arc notches-211, 212; straight line segment widening notches-221, 222; first straight line notch-231; second straight line notch-232; arc notch-233. DETAILED DESCRIPTION

[0033] The following describes the implementation methods 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 without conflict.

[0034] See also Figure 1 , Figure 1 The flowchart of one embodiment of the method for manufacturing a battery casing with explosion-proof notches of the present invention. The method for manufacturing a battery casing with explosion-proof notches of this embodiment comprises the following steps:

[0035] S100, take a battery shell; the material of the battery shell can be an iron-based alloy, a nickel-based alloy, a titanium alloy or an aluminum alloy. In this embodiment, the material of the battery shell is stainless steel, and the thickness of the stainless steel material can be 0.05mm to 0.8mm. Generally, a stainless steel material with a thickness in the range of 0.1mm to 0.3mm is selected as the battery shell 100. In this embodiment, the thickness of the stainless steel material is 0.20mm±0.005mm. Of course, the material of the battery shell can also be other materials such as aluminum alloy. When an aluminum alloy material is used, the thickness of the aluminum alloy material can be 0.2mm to 1.5mm, and an aluminum alloy material with a thickness of 0.5mm is usually selected. The material of the battery shell of the secondary battery in the prior art is generally aluminum alloy. Since the material of aluminum alloy is relatively soft, it is necessary to use a thicker aluminum alloy material for production. When forming an explosion-proof notch 200 on a battery shell 100 made of aluminum alloy material, a groove is generally formed in the area of ​​the explosion-proof notch 200 by stamping or the like in advance to reduce the thickness of the area, and then the explosion-proof notch 200 is formed in the groove. When the strength requirements of the battery case 100 of the battery are the same, the battery case 100 made of stainless steel can be made of thinner material than the battery case 100 made of aluminum alloy, so that the explosion-proof notch 200 can be directly opened on the battery case 100 without first punching a groove on the battery case 100. For example, the thickness of the stainless steel material in this embodiment is 0.20 mm ± 0.005 mm, which is much smaller than the 0.5 mm thickness commonly used when the battery case is made of aluminum alloy.

[0036] See also Figure 2 and Figure 3 In this embodiment, the battery housing 100 is a rectangular parallelepiped in the shape of a thin sheet as a whole, including a top surface 111, a bottom surface 112 opposite to the top surface 111, two oppositely arranged wide side surfaces 121, and two oppositely arranged narrow side surfaces 131. The battery housing 100 of this shape can be used to produce blade batteries, square batteries, etc. Since the two wide side surfaces 121 of the aforementioned battery will be closely attached to the batteries adjacent to both sides during installation, it will prevent the explosion-proof notch 200 from being torn. Therefore, the explosion-proof notch 200 is generally not set on the two wide side surfaces 121 of the battery housing 100. In addition, the top surface 111 of the battery housing 100 is generally the top cover plate of the battery, on which components such as electrodes are arranged, and the area for setting the explosion-proof notch 200 is small, which will also avoid setting the explosion-proof notch 200 on the top surface 111. Therefore, the explosion-proof notch 200 is generally set on the narrow side surface 131 or the bottom surface 112. Of course, it is not ruled out that the explosion-proof notch 200 is stamped on the top cover plate. If it is arranged on the top cover plate, the volume of the processed product can be reduced and the dual requirements of the stamping equipment on size and precision can be reduced.

[0037] Since the battery shell 100 of the blade battery is relatively long, when a battery cell fails, the air pressure in different areas of the shell may be quite different. If the location of the failed battery cell is too far from the explosion-proof notch 200, it will also affect the explosion-proof effect of the explosion-proof structure. Therefore, in this embodiment, the explosion-proof notch 200 is set on the two narrow sides 131. The number of explosion-proof notches 200 can be more than one, which can be determined according to the length of the battery shell 100 (i.e., the length of the battery shell 100 along the side). Figure 2 and Figure 3 The length of the battery shell 100 in the z-axis direction is determined by the length of the battery shell 100. Generally, an explosion-proof structure formed by an explosion-proof notch 200 is set every 300mm in the length direction of the battery shell 100. For a battery shell 100 with a length not exceeding 600mm, only one explosion-proof notch 200 is required. When only one explosion-proof notch 200 is required, the explosion-proof notch 200 can also be set on the bottom surface 112. If the length of the battery shell 100 is greater than 600mm, an explosion-proof notch 200 is added for every additional 300mm, and each explosion-proof notch 200 is evenly arranged along the length direction of the battery shell 100, so that it can be ensured that when a battery cell fails at any part, an explosion-proof notch 200 is set in a relatively close range, so that it can be ensured that when the air pressure inside the battery shell 100 reaches the tearing air pressure value, the explosion-proof notch 200 can be normally torn open to discharge the expanded gas inside the shell 100 to prevent the battery from exploding.

[0038] S200, determining the laser etching path according to the pattern of the explosion-proof notch. The shape of the explosion-proof notch 200 can be a quasi-circular curve, a spline curve, or other curves that do not form a sharp angle. For example, the shape of the explosion-proof notch 200 can be a quasi-circular curve such as a circle, an ellipse, or a runway. Of course, the shape of the explosion-proof notch 200 can also be other curves such as a hyperbola, a scoop, or a parabola. The explosion-proof notch 200 uses a quasi-circular curve or a spline curve, which can avoid including a sharp angle in the shape of the explosion-proof notch 200, thereby facilitating laser etching. If the shape of the explosion-proof notch 200 includes a sharp angle, the laser irradiation position of the laser etching equipment cannot turn along the sharp angle at the previous moving speed at the angle, and needs to stop at the corner point of the angle, and then change direction to complete the turn, which will increase the overall time of laser etching. In addition, when the laser irradiation position stays at a corner point, it is necessary to temporarily turn off the laser to avoid excessive etching depth at the corner point, and then turn on the laser again after changing direction, which also increases the control process of the laser equipment. When the explosion-proof notch 200 adopts a quasi-circular curve, since the quasi-circular curve is an overall smooth curve, no sharp angle is formed on the curve; when using laser to etch the explosion-proof notch 200, it is convenient for the laser irradiation position of the laser etching equipment to move at a uniform speed, avoiding the laser irradiation position from stopping at the corner point of the angle due to the need to turn, thereby increasing the overall etching process time.

[0039] When the explosion-proof notch 200 is in the shape of a closed curve, the laser etching of the explosion-proof notch 200 may sometimes cause the starting point and the end point of the same etching to overlap, so that the same etching cycle may etch twice at the starting point (end point) of the etching, thereby increasing the etching depth at the starting point (end point), which may cause the area to be pierced. In order to avoid this situation, the shape of the explosion-proof notch 200 can also be a curve with a notch 201 formed by cutting off a section on the closed curve. When the explosion-proof notch 200 is etched on the battery housing 100 by laser, a point is selected from the curve as the starting point of etching each time the laser is etched, and another point is selected from the curve as the end point of etching. Generally, when laser etching starts, the two end points of the curve are used as the starting point and end point of etching respectively to etch along the curve; thereafter, each time the predetermined number of etchings is performed, the starting point and the end point of etching are moved along the curve to the midpoint of the curve by a predetermined distance until the etching is completed. Since the curve is not closed, the starting point and the end point will not overlap when the laser etching is performed using the above method, thereby avoiding the situation where the starting point (end point) of the etching may overlap when the shape of the explosion-proof notch 200 is a closed curve, which may cause over-etching at the starting point (end point) of the etching due to the overlap of the starting point and the end point of the same etching by the laser etching device. The linear width W3 of the notch 201 can range from 0.1 mm to 80 mm.

[0040] For example, a curve with a notch 201 can be formed after a section is cut off from the closed curve, and the curve with the notch 201 is used as the shape of the explosion-proof notch 200, so as to avoid the overlap of the starting point and the end point of etching, and make the depth of the explosion-proof notch 200 equal everywhere. Since laser etching is not required at the notch 201, the time of laser etching can be shortened by forming the notch 201 on the explosion-proof notch 200. For the same closed curve, the longer the length of the curve cut off at the notch 201, the shorter the time required for laser etching. Of course, if the length of the curve cut off at the notch 201 is too long, the tearing pressure value of the explosion-proof structure will also increase. In order to avoid the influence of the too long length of the curve cut off at the notch 201 on the tearing pressure value of the explosion-proof structure, and to minimize the time required for laser etching, generally only a small section of the closed curve is cut off to form the notch 201, and the straight line width at the notch 201 is generally 1mm≤W3≤5mm. Within this range, the straight line width of the notch 201 will hardly have an effect on the tearing pressure value of the explosion-proof structure. Of course, when the straight width W3 of the notch 201 is large and may increase the tearing pressure value of the explosion-proof structure, the tearing pressure value of the explosion-proof structure can also be reduced by changing other parameters of the explosion-proof notch 200. In addition, by leaving a notch 201 on the explosion-proof notch 200 without etching, when the explosion-proof notch 200 is torn due to the expansion of the gas inside the shell due to the heating of the battery cell, the notch 201 will not be torn because it is of normal thickness, thereby ensuring that the area enclosed by the explosion-proof notch 200 is connected to the battery shell 100, avoiding the area enclosed by the explosion-proof notch 200 from being torn as a whole and being blown away by high pressure, causing secondary damage to other batteries or water cooling plates and surrounding connection circuits. Similarly, other curves with notches 201 can also be selected as the shape of the explosion-proof notch 200. For example, the shape of the explosion-proof notch 200 can also be a hyperbola, a scoop tongue curve, a parabola, and other non-closed arbitrary spline curves.

[0041] For example, see Figure 4 , a schematic diagram of the structure when the shape of the explosion-proof notch 200 is a circle with a notch 201. The diameter D1 of the circle ranges from 5mm to 80mm, preferably 10mm≤D1≤18mm, for example, D1=15mm. In the figure, the length of the notch 201 is 2mm, and the notch 201 can be set at any position of the circle, and the notch 201 faces the length direction of the rectangular surface where the explosion-proof notch 200 is located (that is, when the explosion-proof notch 200 is set on the narrow side 131 of the shell 100, the notch 201 faces Figure 2 and Figure 3 In the z-axis direction, when the explosion-proof notch 200 is arranged on the bottom surface 112 of the housing 100, the notch 201 faces Figure 2 and Figure 3 in the x-axis direction).

[0042] See also Figure 5 , a schematic diagram of a structure when the shape of the explosion-proof notch 200 is an ellipse with a notch 201. The long axis direction of the ellipse is consistent with the length direction of the battery housing 100 (i.e., the long axis of the ellipse is consistent with the length direction of the battery housing 100). Figure 2 and Figure 3 The distance L1 between the two foci of the ellipse is 5mm≤L1≤80mm, preferably 25mm≤L1≤50mm. The difference between the length L2 of the major axis of the ellipse and the distance L1 between the two foci of the ellipse is 5mm≤(L2-L1)≤80mm, and the value of (L2-L1) is less than or equal to the value of L1, preferably 10mm≤(L2-L1)≤18mm; for example, L1=35mm, L2-L1=15mm. In the figure, the length of the notch 201 is 2mm, and the notch 201 is preferably set at one end point of the major axis of the ellipse.

[0043] See also Figure 6 , a schematic diagram of the structure when the shape of the explosion-proof notch 200 is a runway shape with a notch 201. The explosion-proof notch 200 includes a symmetrically arranged semicircular notch 211 and a semicircular notch 212 and two straight line segment widening notches (221, 222) connecting the corresponding endpoints of the semicircular notch 211 and the semicircular notch 212. Among them, the straight line segment widening notch 221 is used to connect a pair of endpoints corresponding to the semicircular notch 211 and the semicircular notch 212, and the straight line segment widening notch 222 is used to connect another pair of endpoints corresponding to the semicircular notch 211 and the semicircular notch 212. The directions of the straight line segment widening notch 221 and the straight line segment widening notch 222 are consistent with the length direction of the battery shell 100 (that is, the straight line segment widening notch 221 and the straight line segment widening notch 222 are consistent with the length direction of the battery shell 100). Figure 2 and Figure 3 The diameter D2 of the semicircular notch 211 and the semicircular notch 212 is in the range of 5 mm to 80 mm, preferably 10 mm ≤ D2 ≤ 18 mm; the length L3 of the straight line segment widening notch 221 and the straight line segment widening notch 222 is 5 mm ≤ L3 ≤ 80 mm; for example, D2 = 15 mm, preferably L3 = 35 mm. In the figure, the length of the notch 201 is 2 mm, and the notch 201 is preferably set at the midpoint of the semicircular notch 211 or the semicircular notch 212.

[0044] When the proportion of the gap 201 in the closed curve is large, the actual shape of the gap cannot be accurately described by the gap length. In this case, the shape of the gap can also be described by the ratio of the length of the closed curve to the length of the cut-off portion. The ratio of the length of the closed curve to the length of the cut-off portion is in the range of 12 / 11 to 72. Taking the shape of the closed curve as a circle as an example, the shape of the explosion-proof notch 200 after the notch 201 is formed is an arc of 30° to 355°. Generally, the ratio of the length of the closed curve to the length of the cut-off portion is 2 to 12, that is, the explosion-proof notch 200 generally adopts an arc shape of 180° to 330°, preferably an arc shape of 270°. Of course, the explosion-proof notch 200 can also be an arc with an arc θ of 60°, 90°, 120° or 150°. Under the same circumstances, when explosion-proof notch 200 is in the shape of an arc with an arc θ less than 90°, the air pressure required to tear explosion-proof notch 200 will increase significantly; when explosion-proof notch 200 is in the shape of an arc with an arc θ between 90° and 180°, the air pressure required to tear explosion-proof notch 200 will decrease significantly with the increase of the arc θ; when explosion-proof notch 200 is in the shape of an arc with an arc θ greater than 180°, the air pressure required to tear explosion-proof notch 200 changes little with the arc θ value.

[0045] The explosion-proof notch 200 may also be in the form of two intersecting straight line notches. Figure 7 and Figure 8 , the explosion-proof notch 200 may also be composed of a first linear notch 231 and a second linear notch 232, wherein the first linear notch 231 and the second linear notch 232 intersect at a point O3. It should be noted that the first linear notch 231 and the second linear notch 232 only intersect at the point O3 in shape. In the step S200, when the laser etching path is determined according to the pattern of the explosion-proof notch 200, the second linear notch 232 is divided into two segments at the intersection O3 of the first linear notch 231 and the second linear notch 232, so that the two segments of the second linear notch 232 together with the first linear notch 231 form a laser etching path composed of three non-intersecting line segments. Of course, the first linear notch 231 may also be divided into two segments, so as to form a laser etching path composed of three non-intersecting line segments.

[0046] Since the laser etching path is composed of three non-intersecting line segments, when the laser is used to etch the first linear mark 231 and the second linear mark 232 in the step S400, the etching paths of the first linear mark 231 and the second linear mark 232 are also non-intersecting. That is, during the laser etching process, each time the first linear mark 231 and the second linear mark 232 are etched once (i.e. within one etching cycle), the point O3 will only be etched along with the first linear mark 231 (when the laser etching path divides the first linear mark 231 into two segments, the point O3 will only be etched along with the second linear mark 232), so that the point O3 is only etched once within one etching cycle, and will not be etched twice by being etched along with the first linear mark 231 and the second linear mark 232 at the same time, thereby avoiding the situation where the etching depth at the intersection O3 is increased due to too many etching times, resulting in the point being etched through. Thus, the depths of the first linear score 231 , the second linear score 232 , and the intersection O3 of the first linear score 231 and the second linear score 232 are all the same.

[0047] In this embodiment, the first linear notch 231 is along the width direction of the narrow side surface 131 of the housing 100 (i.e. Figure 7 The length of the first linear score 231 can be determined according to the width of the narrow side 131 of the shell 100. If the length of the first linear score 231 is too small, when the air pressure inside the shell 100 is too high and the explosion-proof score 200 needs to be torn, the difficulty of tearing the explosion-proof score 200 will increase, and the opening formed after tearing will be small, which will slow down the speed of gas discharge from the shell 100. If the length of the first linear score 231 is too close to the width of the narrow side 131 of the shell 100, it will affect the overall strength of the shell 100. The length L4 of the first linear score 231 can be 6mm to 80mm, and generally 12mm≤L4≤20mm is taken, and preferably L4=16mm. The second linear score 232 is along the length direction of the narrow side 131 of the shell 100 (i.e. Figure 7 The second linear score 232 is arranged in the z-axis direction of the shell 100. Since the length of the narrow side 131 of the shell 100 is relatively large, it generally does not limit the length of the second linear score 232. Therefore, the length L5 of the second linear score 232 can be relatively long, so that when the gas pressure inside the shell 100 is too high and the explosion-proof score 200 needs to be torn, a longer opening can be torn to quickly discharge the high-pressure gas inside the shell 100. The length L5 of the second linear score 232 can be 12mm~100mm, and generally 20mm≤L5≤50mm is taken, and preferably L5=32mm. It can be understood that when the explosion-proof score 200 is set on the bottom surface 112, the second linear score 212 is along the length direction of the bottom surface 112 of the shell 100 (that is, Figure 1 and Figure 2 The x-axis direction in .

[0048] In this embodiment, the intersection O3 of the first linear score 231 and the second linear score 232 is the midpoint of the first linear score 231 and the second linear score 232, that is, the first linear score 231 and the second linear score 232 are perpendicular to each other and bisect each other, so that the shape of the explosion-proof score 200 is a symmetrical "cross". Since the explosion-proof score 200 is arranged in four directions at the intersection O3 of the first linear score 231 and the second linear score 232, it can be ensured that the intersection O3 can be easily torn when the air pressure inside the shell 100 is too high, and it is avoided that the explosion-proof score 200 cannot be torn when the air pressure inside the shell 100 exceeds the predetermined tearing air pressure value due to a large error in the depth parameter of the explosion-proof score 200.

[0049] Since the explosion-proof notch 200 is in the shape of a "cross", when the air pressure inside the shell 100 is too high and the explosion-proof notch 200 is torn, the area that can be rolled outward under the impact of the high-pressure gas is small, so that a large opening cannot be formed, which still affects the discharge speed of the high-pressure gas inside the shell 100. In order to further increase the speed of discharging the high-pressure gas inside the shell 100 after the explosion-proof notch 200 is torn, the explosion-proof notch 200 can also include at least one arc notch 233, and the center of each arc notch 233 is the intersection O3 of the first straight line notch 231 and the second straight line notch 232. The arc notch 233 generally adopts an arc shape with an arc of about 90°, and the two ends of each arc notch 233 intersect with the first straight line notch 231 and the second straight line notch 232 respectively. The diameter of the arc notch 233 is less than or equal to the length of the shorter section of the first straight line notch 231 and the second straight line notch 232.

[0050] See also Fig. 9In this embodiment, the explosion-proof notch 200 includes two arc notches 233 of equal diameter. The diameter of the two arc notches 233 is 15 mm, which is slightly smaller than the length of the first linear notch 231; and the two arc notches 233 are symmetrical along the intersection O3. The curvature of the two arc notches 233 is 90°; of course, the curvature of the two arc notches 233 can also be greater than 90°. The notch depth of the two arc notches 233 and the notch depth at the intersection of the two arc notches 233 with the first linear notch 231 and the second linear notch 232 are equal to the notch depth of the first linear notch 231 and the second linear notch 232. By providing two arc notches 233, when the air pressure inside the shell 100 is too high and causes the explosion-proof notch 200 to tear, the two fan-shaped areas formed by the two arc notches 233 and the first straight line notch 231 and the second straight line notch 232 will completely roll outward during the tearing process, thereby greatly increasing the opening area formed when the explosion-proof notch 200 is torn, so that the high-pressure gas inside the battery shell 100 can be quickly discharged.

[0051] S300, adjust the parameters of the laser etching equipment according to the material and thickness of the battery shell; and calibrate and adjust to ensure that the material can be accurately processed. In this embodiment, the battery shell 100 is made of stainless steel with a thickness of 0.20mm±0.005mm, the power of the laser etching equipment is 10W~2000W, the frequency parameter is 1KHZ~1000, and the speed parameter is 1mm / s~4000mm / s.

[0052] S400, place the battery shell on the processing platform of the laser etching equipment, and use the laser etching equipment to etch explosion-proof marks on the battery shell according to the laser etching path. Fig.10In this embodiment, the cross-sectional shape of the explosion-proof notch 200 is a trapezoid; the connection between the waist and the lower bottom of the trapezoid is a rounded structure. Of course, in other embodiments, the cross-sectional shape of the explosion-proof notch 200 may also be other shapes such as "V" or "U". The value of the lower bottom width of the cross section of the explosion-proof notch 200 is in the range of 0 to 0.5 mm. In this embodiment, the explosion-proof notch 200 is formed by laser etching. Laser etching is the process of using a high-energy laser beam to irradiate the surface of the etched workpiece to melt and vaporize it, forming a groove of a certain depth to achieve the purpose of etching the material. The characteristics of laser etching are high precision, small width of the notch, high etching yield, high stability, no consumables, no pollution, and low cost. In the prior art, the explosion-proof notch 200 of the aluminum alloy housing is generally formed by stamping. Due to the limitation of the stamping process, the existing machine cannot take into account both the processing size and the high-precision requirements. It is necessary to purchase or invest a large number of high-precision stamping equipment, and the manufacturing cost is very high. The existing stamping equipment cannot accurately control the depth of the formed explosion-proof notch 200, and the cross-sectional width (i.e., the groove width) of the explosion-proof notch 200 is also generally wide. The explosion-proof notch 200 formed by laser etching can accurately control the depth and width of the notch, thereby greatly reducing the groove width of the explosion-proof notch 200.

[0053] The tearing pressure value at the explosion-proof notch 200 is mainly affected by the notch residual value t of the explosion-proof notch 200 and the thickness T of the battery housing 100. Fig.10 , the residual value of the explosion-proof notch 200 is defined as the remaining thickness of the battery shell 100 after thinning at the explosion-proof notch 200. If the ratio T / t of the thickness T of the battery shell 100 and the residual value t of the explosion-proof notch 200 is large, the strength of the battery shell 100 will be greatly reduced. When the battery collides with other products during use, it is very likely that the battery shell 100 will be broken, allowing external gas to enter the battery shell 100 through the rupture and react chemically with the material of the battery cell, which will cause battery failure and even battery explosion accidents. If the ratio T / t is small, when the internal gas pressure of the battery reaches the upper limit pressure, the pressure relief port torn from the explosion-proof notch 200 will be relatively small, so that the gas inside the battery cannot be discharged in time, and it may also cause the battery to over-expand and cause an explosion.

[0054] In this embodiment, the ratio of the thickness T of the battery shell 100 to the residual value t of the explosion-proof notch 200 is in the range of 1.1≤T / t≤30. Generally, the ratio of T / t is in the range of 1.5 to 10. For example, when the battery shell 100 is made of a stainless steel material with a thickness of 0.05mm to 0.8mm, the residual value t of the explosion-proof notch 200 is generally 0.01mm to 0.3mm, preferably 0.01mm to 0.08mm. When the battery shell 100 is made of an aluminum alloy material with a thickness of 0.2mm to 1.5mm, the residual value t of the explosion-proof notch 200 is generally 0.05mm to 0.5mm, preferably 0.05mm to 0.2mm. Specifically in this embodiment, since the battery housing 100 is made of 0.20 mm ± 0.005 mm stainless steel material, the value range of the residual value t of the explosion-proof notch 200 is generally: 0.02 mm ≤ t ≤ 0.08 mm.

[0055] In this embodiment, the angle a between the waist of the trapezoid and the vertical direction (i.e., the height of the trapezoid) and the value of the bottom width W1 of the trapezoid will also have a certain impact on the tearing pressure value of the explosion-proof structure. The value of the angle a between the waist of the trapezoid and the height of the trapezoid is in the range of 5° to 60°; preferably 25°≤a≤45°. The bottom width W1 of the trapezoid is preferably 0.03mm≤W1≤0.1mm.

[0056] S500, post-processing the battery shell after etching. The oxide layer remaining during laser etching is removed by post-processing cleaning, and the etching quality of details is improved by fine-tuning.

[0057] When the battery cell inside the battery is damaged, a large amount of heat will be emitted and / or gas will be released, causing the pressure inside the battery shell 100 to expand rapidly. If the pressure is not released in time, when the air pressure inside the battery shell 100 is too high, there is a risk of explosion. In this embodiment, by setting an explosion-proof notch 200 on the battery shell 100, if the air pressure inside the battery shell 100 is too high, as the air pressure increases, the explosion-proof notch 200 will be torn open under the action of the high air pressure, so that the gas inside the battery shell 100 is discharged from the torn part of the explosion-proof notch 200, thereby releasing the high-pressure gas inside the battery shell 100, preventing the battery from exploding, and ensuring the personal safety of the producer and user. The air pressure value that causes the explosion-proof notch 200 to be torn open is the tearing air pressure value of the explosion-proof structure. In addition, since the explosion-proof notch 200 is directly etched on the battery shell 100 to form an explosion-proof structure in the present embodiment, the explosion-proof structure and the battery shell 100 are integrated as a whole. Compared with the existing technology of opening a pressure relief hole and welding an explosion-proof valve at the pressure relief hole, the process is simpler and does not require the use of a welding process, thereby avoiding the explosion-proof effect of the explosion-proof structure being affected by errors in the welding process.

[0058] In this embodiment, a stainless steel shell 100 with a thickness of 0.20mm±0.005mm is used, and an explosion-proof notch 200 with a trapezoidal cross-sectional shape and a circular shape with a notch 201 is used as a verification object to verify the effect of the ratio of the thickness T of the battery shell 100 to the residual value t of the explosion-proof notch 200 on the explosion-proof effect. Among them, the battery shell 100 is in the shape of a rectangular parallelepiped, the explosion-proof notch 200 is arranged on the narrow side 131, the straight width of the notch 201 is 2mm, the bottom width W1 of the trapezoid is 0.08mm, the angle between the waist of the trapezoid and the height of the trapezoid is 25°≤a≤45°, and the diameter of the circle is 15mm. Since the thickness of the stainless steel battery shell 100 is not easy to change, the ratio of T / t is changed by changing the residual value of the notch when the thickness of the stainless steel battery shell 100 is fixed, and multiple verifications are carried out for each value of the residual value t of the notch, and the verification data are shown in Table 1:

[0059]

[0060] Table 1

[0061] The pressure speed in the table is the speed of charging the battery shell during the test. Since the above verification only cares about the tearing pressure value when the explosion-proof notch 200 is torn, and does not simulate the process of battery shell explosion, the time required for the explosion-proof notch 200 to tear is not used as a verification parameter.

[0062] This embodiment also uses a stainless steel shell 100 with a thickness of 0.20mm±0.005mm, and uses an explosion-proof notch 200 with a trapezoidal cross-sectional shape and a circular notch 201 as a verification object to verify the influence of the diameter of the circle on the explosion-proof effect. Among them, the battery shell 100 is in the shape of a rectangular parallelepiped, the explosion-proof notch 200 is set on the narrow side 131, the straight width of the notch 201 is 2mm, the bottom width W1 of the trapezoid is 0.08mm, the angle between the waist of the trapezoid and the height of the trapezoid is 25°≤a≤45°, and the residual value t of the notch is 0.04mm. Multiple verifications were carried out for each diameter, and the verification data are shown in Table 2:

[0063]

[0064] Table 2

[0065] The valve opening time in the table refers to the time required from the start of pressurization to the tearing of the explosion-proof notch 200; since this verification and subsequent verifications are simulations of the battery shell explosion process, the valve opening time parameter is added. The valve opening time in the range of 30s to 40s is a relatively ideal time.

[0066] This embodiment also uses a stainless steel shell 100 with a thickness of 0.20mm±0.005mm, and an explosion-proof notch 200 with a trapezoidal cross-sectional shape, an overall shape of a 120° arc, and an arc diameter of 15mm as a verification object, and verifies the influence of the bottom width W1 of the trapezoid on the explosion-proof effect. Among them, the battery shell 100 is in the shape of a rectangular parallelepiped, the explosion-proof notch 200 is set on the narrow side 131, the notch residual value t is 0.04mm, and the angle between the waist of the trapezoid and the height of the trapezoid is 25°≤a≤45°. Multiple verifications have been carried out for the bottom width W1 of each trapezoid, and the verification data are shown in Table 3:

[0067]

[0068] Table 3

[0069] This embodiment also uses a stainless steel shell 100 with a thickness of 0.20mm±0.005mm, and takes an explosion-proof notch 200 with a trapezoidal cross-sectional shape and an arc shape as a verification object, and verifies the influence of the arc curvature (used to characterize the ratio of the length of the closed curve to the length of the cut portion) and the diameter on the explosion-proof effect. Among them, the battery shell 100 is in the shape of a rectangular parallelepiped, the explosion-proof notch 200 is set on the narrow side 131, the notch residual value t is 0.04mm, and the angle between the waist of the trapezoid and the height of the trapezoid is 25°≤a≤45°. Multiple verifications have been carried out for the curvature and diameter of each arc, and the verification data are shown in Table 4:

[0070]

[0071]

[0072] Table 4

[0073] In the present embodiment, a groove structure with a cross-section that is wide at the top and narrow at the bottom is formed by laser etching as the explosion-proof notch 200. The formed explosion-proof notch 200 has higher precision. When etching the explosion-proof notch 200, the tearing pressure value at the explosion-proof notch 200 can be adjusted by selecting the bottom width W1 of the groove structure and the angle a between the side of the groove structure cross-section and the vertical direction. It is more convenient to adjust the tearing pressure value at the explosion-proof notch 200.

[0074] The present invention also discloses a secondary battery, which can be a power battery or an energy storage battery, and the shell of the secondary battery can be made by the method for making a battery shell with explosion-proof notches in any of the above embodiments. Of course, the secondary battery also includes a battery cell accommodated in the battery shell and other structures necessary for conventional secondary batteries, which are all existing technologies and will not be described in detail here.

[0075] The present invention also discloses an electric device, the electric device comprising a secondary battery of any of the above embodiments, so as to supply power to the electric device through the secondary battery. For example, the electric device may be a new energy electric vehicle or a hybrid vehicle. It is understood that the electric device may also be an electric tool, an energy storage device, a power device, or other devices driven by electricity, such as a mobile phone, a tablet computer, a computer, and a drone.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. 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 solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for manufacturing a battery casing with explosion-proof notches, characterized in that: The following steps are involved: S100, taking a battery casing; S200, determining a laser etching path according to a pattern of explosion-proof notches, wherein the explosion-proof notches include a first linear notch and a second linear notch, the first linear notch and the second linear notch intersect at one point, and the notch depths of the first linear notch, the second linear notch and the intersection of the first linear notch and the second linear notch are the same; the explosion-proof notches also include at least one arc notch, the center of the arc notch is the intersection of the first linear notch and the second linear notch, and both ends of the arc notch intersect with the first linear notch and the second linear notch respectively; When determining the laser etching path, the first linear score is divided into two segments at the intersection of the first linear score and the second linear score, thereby forming a laser etching path including three non-intersecting line segments together with the second linear score; or When determining the laser etching path, the second linear score is divided into two segments at the intersection of the first linear score and the second linear score, thereby forming a laser etching path including three mutually non-intersecting line segments together with the first linear score. S300, adjusting laser etching parameters according to the material and thickness of the battery shell; S400, etching an explosion-proof notch on the battery housing according to an etching path by laser; the explosion-proof notch is a groove structure with a wide upper portion and a narrow lower portion in cross section; S500, post-processing the etched battery shell.

2. The method for manufacturing a battery casing with explosion-proof notches according to claim 1, characterized in that: The battery shell is made of iron-based alloy material, nickel-based alloy material, titanium alloy material or aluminum alloy material.

3. The method for manufacturing a battery casing with explosion-proof notches according to claim 2, characterized in that: The battery shell is made of stainless steel, and the thickness of the stainless steel is 0.05 mm to 0.8 mm; the residual value of the explosion-proof notch is 0.01 mm to 0.3 mm, wherein the residual value of the notch is defined as the remaining thickness of the battery shell after thinning at the explosion-proof notch; or The battery shell is made of aluminum alloy material, the thickness of the aluminum alloy material is 0.2mm-1.5mm, and the residual value of the explosion-proof notch is 0.05mm-0.5mm, wherein the residual value of the notch is defined as the remaining thickness of the battery shell after thinning at the explosion-proof notch.

4. The method for manufacturing a battery casing with explosion-proof notches according to claim 3, characterized in that: When the shell is made of stainless steel, the residual value of the explosion-proof notch is 0.01 mm to 0.08 mm; when the shell is made of aluminum alloy, the residual value of the explosion-proof notch is 0.05 mm to 0.2 mm.

5. The method for manufacturing a battery casing with explosion-proof notches according to any one of claims 1 to 4, characterized in that: The cross-sectional shape of the explosion-proof notch is a trapezoid, "V" shape or "U" shape that is wide at the top and narrow at the bottom, and the angle between the side of the cross-sectional shape and the vertical direction is 5° to 60°; the bottom width of the cross-sectional area of ​​the explosion-proof notch is 0 to 0.5 mm.

6. The method for manufacturing a battery casing with explosion-proof notches according to claim 5, characterized in that: The angle between the side of the cross-sectional shape and the vertical direction is 25° to 45°; the bottom width of the cross-sectional area of ​​the explosion-proof notch is 0.03 mm to 0.1 mm.

7. A secondary battery, characterized in that: The invention comprises a battery shell manufactured by the method for manufacturing a battery shell with explosion-proof notches as claimed in any one of claims 1 to 6.

8. An electrical equipment, characterized in that: Comprising the secondary battery as claimed in claim 7.

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