Two-way bending device and secondary battery including the same

Abstract

The disclosed invention relates to a two-way bending device, and includes a rupture disk having a notch portion that ruptures when a pressure exceeding a preset value acts thereon, and a mounting portion provided along the edge of the rupture disk. Here, the notch portion includes a first notch portion formed along the left half corner of the rupture disk, and a second notch portion formed along the right half corner of the rupture disk, which is spaced apart so as not to be connected to the first notch portion.

Description

Technical Field

[0001] The present invention relates to a two-way bending device and a secondary battery including the same, and more particularly, to a two-way bending device and a secondary battery including the same that improve safety by guiding the discharge direction of dangerous factors such as high-temperature gas, flame, and heating particles ejected from a secondary battery in which thermal runaway has occurred to both sides away from the upper side.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0152444 filed on November 15, 2022, and all contents disclosed in the literature of the Korean patent application are included as part of this specification.

Background Art

[0003] Unlike primary batteries, secondary batteries can be recharged and have been extensively researched and developed in recent years due to their potential for miniaturization and high capacity. With the increasing development and demand for mobile devices, as well as the emergence of electric vehicles and energy storage systems in line with the contemporary requirements of environmental protection, the demand for secondary batteries as an energy source has been increasing even more rapidly.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries according to the shape of the battery case. The electrode assembly mounted inside the battery case in a secondary battery is a power generation element capable of charge and discharge, which has a laminated structure of electrodes and a separator.

[0005] Since secondary batteries are required to be used continuously for a long time, it is necessary to effectively control the heat generated during the charge and discharge process. If the cooling of the secondary battery is not carried out smoothly, the temperature rise will cause an increase in current, and the increase in current will cause a positive feedback chain reaction that will cause the temperature to rise again. As a result, it will lead to a catastrophic state of thermal runaway.

[0006] When thermal runaway occurs in a secondary battery, both the temperature and pressure will rise. If the temperature and pressure rise beyond the heat and pressure resistance performance of the secondary battery, the structure of the secondary battery will eventually collapse. When the structure of the secondary battery collapses, a large amount of air is supplied inside, causing fires and explosions to spread uncontrollably to the surroundings, and accidents caused by this will result in significant damage.

[0007] To prevent such structural collapse of the secondary battery, secondary batteries, especially cylindrical batteries and prismatic batteries, are often equipped with a venting device. The venting device corresponds to a kind of safety valve that relieves pressure by breaking when the pressure inside the secondary battery exceeds a specific level.

[0008] However, most of the current venting devices are structured to discharge dangerous factors such as high-temperature gas, flame, and heated particles directly upward. Such venting devices may pose safety problems by ejecting dangerous factors in the direction towards the driver and passengers when the secondary battery is used in an electric vehicle.

Summary of the Invention

Problems to be Solved by the Invention

[0009] An object of the present invention is to provide a venting device that improves safety by guiding the discharge direction of dangerous factors such as high-temperature gas, flame, and heated particles ejected from a secondary battery in which thermal runaway has occurred to both sides away from directly above, and a secondary battery including the same.

[0010] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those of ordinary skill in the art from the description of the invention described below.

Means for Solving the Problems

[0011] The present invention relates to a bi-directional bending device. In one example, it includes a rupture disk having a notch portion that ruptures when a pressure exceeding a preset value acts thereon, and a mounting portion provided along the edge of the rupture disk. Here, the notch portion includes a first notch portion formed along the left half corner of the rupture disk, and a second notch portion formed along the right half corner of the rupture disk and separated so as not to be connected to the first notch portion.

[0012] When a pressure exceeding a preset value acts on the rupture disk, the first notch portion and the second notch portion rupture so as to form a butterfly shape.

[0013] In one embodiment of the present invention, the first notch portion and the second notch portion may have a notch depth that increases as they move farther from a virtual symmetry line that crosses the center where they are separated from each other.

[0014] For example, the first notch portion and the second notch portion may have a linear change in the notch depth.

[0015] Also, the first notch portion and the second notch portion may have a larger rate of change in the notch depth as they move farther from the symmetry line.

[0016] Or, as another example, the first notch portion and the second notch portion may have a discontinuous stepped change in the notch depth.

[0017] Thereby, the first notch portion and the second notch portion may start to rupture from the left and right corners with a deeper notch depth in proportion to the magnitude of the pressure exceeding the preset value.

[0018] On the other hand, the present invention provides a secondary battery including a battery case having a space for accommodating an electrode assembly, and the above bi-directional bending device in which one or more are mounted on at least one surface of the battery case.

[0019] The above-described two-way venting device is airtightly mounted so that the first notch portion and the second notch portion are exposed to the outside with respect to the venting hole formed in the battery case.

[0020] The mounting portion can be fixed by welding to the battery case in a state aligned with the venting hole.

[0021] Alternatively, the mounting portion can include an edge in the form of a wall that is inserted into the venting hole.

[0022] And the mounting portion can include a support frame that crosses the center where the first notch portion and the second notch portion are separated from each other.

Advantages of the Invention

[0023] According to the two-way venting device of the present invention having the above-described configuration, notch portions that rupture when a pressure exceeding a set reference acts are formed separately from each other along the edges of the left and right halves of the rupture disk. Thus, when the rupture disk ruptures, the first notch portion and the second notch portion rupture so as to form a butterfly shape, and dangerous factors such as high-temperature gas, flames, and heated particles are discharged to both sides rather than directly above the venting device. As a result, when the venting device of the present invention is applied to a medium to large-sized secondary battery for an automobile, the safety can be improved by ejecting dangerous factors to the side rather than directly above the driver and passengers.

[0024] In addition, in the two-way bending device of the present invention, the notch depth of the notch portion can be formed deeper toward the left and right corners of the rupture disk. As a result, at the initial stage of thermal runaway occurring inside the secondary battery, the notch portion ruptures slightly to discharge only a small amount of ejecta in both side directions, thereby suppressing the promotion of combustion due to air inflow and simultaneously preventing the discharge directly upward to the maximum extent. And when thermal runaway progresses to the final state and rapid pressure discharge is required, the entire notch portion can rupture to secure the maximum discharge area. Therefore, the two-way bending device of the present invention can significantly improve the safety of the secondary battery.

[0025] However, the technical effects that can be obtained by the present invention are not limited to the above-described effects, and other effects not mentioned can be clearly understood by those of ordinary skill in the art from the description of the invention described below.

[0026] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further understand the technical idea of the present invention together with the detailed description of the invention to be described later. Therefore, the present invention should not be construed as being limited only to the matters described in such drawings.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

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Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0028] Since the present invention can be subjected to various modifications and can have various embodiments, specific embodiments will be described in detail below.

[0029] However, this is not intended to limit the present invention to specific embodiments, and it can be understood to include all modifications, equivalents, or alternatives included in the spirit and technical scope of the present invention.

[0030] In the present invention, terms such as "including" and "having" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and do not preclude the presence or addition possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0031] Also, in the present invention, when a portion such as a layer, film, region, or plate is described as being "on" another portion, this includes not only the case where it is "directly on" another portion but also the case where there is another portion in between. Conversely, when a portion such as a layer, film, region, or plate is described as being "under" another portion, it includes not only the case where it is "directly under" another portion but also the case where there is another portion in between. Also, in this application, being "disposed on" can include not only the upper portion but also the case of being disposed on the lower portion.

[0032] The present invention relates to a two-way bending device. In one example, it includes a rupture disk having a notch portion that ruptures when a pressure exceeding a preset value acts thereon, and a mounting portion provided along the edge of the rupture disk. Here, the notch portion includes a first notch portion formed along the left half corner of the rupture disk, and a second notch portion that is separated so as not to be connected to the first notch portion and is formed along the right half corner of the rupture disk.

[0033] When a pressure exceeding a preset value acts on the rupture disk, the first notch portion and the second notch portion rupture so as to form a butterfly shape.

[0034] According to the two-way bending device of the present invention having such a configuration, notch portions that rupture when a pressure exceeding a reference acts are formed separately from each other along the edges of the left half and the right half of the rupture disk. As a result, when the rupture disk ruptures, the first notch portion and the second notch portion rupture so as to form a butterfly shape, and dangerous factors such as high-temperature gas, flames, and heating particles are discharged to both sides instead of directly above the bending device.

[0035] As a result, when the bending device of the present invention is applied to a medium or large-sized secondary battery for automobiles, it can improve safety by ejecting dangerous factors to the side instead of directly above the driver or passengers.

[0036] Hereinafter, with reference to the accompanying drawings, specific embodiments of the two-way bending device 100 according to the present invention and the secondary battery 200 including the same will be described in detail. For reference, the front-rear, up-down, left-right directions specifying relative positions used in the following description are for helping the understanding of the invention, and are based on the directions shown in the drawings unless otherwise defined.

[0037] (First Embodiment) FIG. 1 is a drawing showing an embodiment of a two-way bending device 100 according to the present invention, and FIG. 2 is a cross-sectional view taken along the line "A-A" of FIG. 1.

[0038] The present invention shown in the figure is a two-way bending device 100, including a rupture disk 110 having a notch portion 112 that ruptures when a pressure exceeding a preset value acts thereon, and a mounting portion 120 provided along the edge of the rupture disk 110.

[0039] The rupture disk 110 is a thin plate-like member made of a metal material, and a notch portion 112 having a notch processed on the surface is formed thereon. The two-way bending device 100 is mounted on the secondary battery 200. When the internal pressure of the sealed battery case 210 rises, tensile deformation occurs throughout the thin rupture disk 110 due to the pressure, and the notch portion 112 with weak strength breaks to relieve the internal pressure of the case 210.

[0040] The mounting portion 120 is an edge portion where the two-way bending device 100 is coupled to the case 210 of the secondary battery 200, and also serves to structurally support the rupture disk 110. The form of the mounting portion 120 can be provided in various ways. For example, it can be in the form of a plate thicker than the rupture disk 110, or in a well form where the protruding side wall 122 surrounds the rupture disk 110.

[0041] Here, the two-way bending device 100 of the present invention includes a pair of notch portions 112-1 and 112-2 that are independent of each other. Specifically, the notch portion 112 in the present invention includes a first notch portion 112-1 formed along the left half corner of the rupture disk 110, and a second notch portion 112-2 formed along the right half corner of the rupture disk 110 and separated so as not to be connected to the first notch portion 112-1.

[0042] Referring to FIG. 2, the first notch portion 112-1 and the second notch portion 112-2 are separated from each other with respect to a virtual symmetry line SL that crosses the approximate center of the rupture disk 110. That is, since there is no notching in the central region of the rupture disk 110 that separates the first notch portion 112-1 and the second notch portion 112-2, the original thickness of the rupture disk 110 is maintained, and notching is performed linearly along the left and right half-plane corners of the rupture disk 110, respectively, whereby the first notch portion 112-1 and the second notch portion 112-2 are formed. The first notch portion 112-1 and the second notch portion 112-2, which are thin in thickness, have a lower rupture strength than other portions of the rupture disk 110. Therefore, when a pressure exceeding a specified level acts, the rupture disk 110 ruptures along the first notch portion 112-1 and the second notch portion 112-2.

[0043] FIG. 3 is a drawing showing the two-way bending device 100 in a state where the first notch portion 112-1 and the second notch portion 112-2 are ruptured, respectively. As shown in the drawing, when ruptures occur along the U-shaped line-like first notch portion 112-1 and second notch portion 112-2, with the central region of the rupture disk 110 that separates the first notch portion 112-1 and the second notch portion 112-2 as a support, the first notch portion 112-1 and the second notch portion 112-2 are lifted upward by the pressure from the inside. In other words, when a pressure exceeding a preset value acts on the two-way bending device 100, the rupture disk 110 ruptures in the left and right directions such that the first notch portion 112-1 and the second notch portion 112-2 form a butterfly shape. As a result, gases, flames, etc. ejected from the inside of the secondary battery 200 to which the two-way bending device 100 is attached are discharged obliquely to both sides instead of directly upward.

[0044] (Second Embodiment) FIGS. 4 to 6 show a second embodiment of the two-way bending device 100 of the present invention. In particular, as shown in FIG. 2, a cross-section of the incision surface along the first notch portion 112-1 and the second notch portion 112-2 is shown.

[0045] According to the illustrated second embodiment, the first notch portion 112-1 and the second notch portion 112-2 are configured such that the notch depth increases as they move away from the virtual symmetry line SL that crosses the center and is separated from each other on the rupture disk 110. That is, the notch depth is formed deepest at the ends of the left and right half planes of the rupture disk 110.

[0046] According to such a second embodiment, when a pressure exceeding a preset value acts on the rupture disk 110, the first notch portion 112-1 and the second notch portion 112-2 start to rupture from the left and right corners with a deeper notch depth in proportion to the magnitude of the acting pressure. That is, since the rupture strength decreases as the notch depth increases, when a pressure exceeding the reference acts, the left and right corners with a deeper notch depth rupture first.

[0047] Also, when the pressure acting on the rupture disk 110 is sufficient to rupture the left and right corners where the first notch portion 112-1 and the second notch portion 112-2 are thinnest, but the size is insufficient to rupture the thicker portions, the first notch portion 112-1 and the second notch portion 112-2 do not rupture entirely, and only a part of the left and right corners may rupture. That is, the second embodiment is configured such that only a part of the first notch portion 112-1 and the second notch portion 112-2 can rupture, and the opening degree of the first notch portion 112-1 and the second notch portion 112-2 increases in proportion to the acting pressure.

[0048] According to such a second embodiment, as the thermal runaway progresses inside the secondary battery 200 with the two-way bending device 100 mounted thereon and the internal pressure gradually increases, the opening degrees of the first notch portion 112-1 and the second notch portion 112-2 will gradually increase corresponding to the rising pressure level. Therefore, in the initial stage of thermal runaway, by making the first notch portion 112-1 and the second notch portion 112-2 rupture slightly and discharge only a small amount of ejecta in both side directions, it is possible to suppress the promotion of combustion due to air inflow and at the same time prevent the discharge directly upward to the maximum extent.

[0049] Also, when the thermal runaway progresses to the final state and a rapid pressure discharge is required, the entire first notch portion 112-1 and the second notch portion 112-2 can rupture to secure the maximum discharge area. FIGS. 7 and 8 exemplarily show two states with different opening degrees depending on the rupture degree of the first notch portion 112-1 and the second notch portion 112-2. The state in FIG. 8 is a case where the opening degree is larger than that in FIG. 7, and due to the higher pressure acting on the rupture disk 110, the entire first notch portion 112-1 and the second notch portion 112-2 rupture to form the maximum opening degree.

[0050] On the other hand, FIGS. 4 to 6 show different states in which the thicknesses of the first notch portion 112-1 and the second notch portion 112-2 gradually become thinner toward the left and right corners.

[0051] FIGS. 4 and 5 show embodiments in which the change in the notch depth with respect to the first notch portion 112-1 and the second notch portion 112-2 forms a linear form. In the embodiment of FIG. 4, based on the virtual symmetry line SL that crosses the center where the first notch portion 112-1 and the second notch portion 112-2 are separately arranged on the rupture disk 110, the notch depth becomes deeper in the form of a straight line of a linear function as it moves away from the symmetry line SL. In contrast, in the embodiment of FIG. 5, although the notch depth changes linearly, it is not in the form of a straight line of a linear function, but rather in the form of a curve in which the change rate of the notch depth increases as it moves away from the symmetry line SL.

[0052] The embodiment of FIG. 5 is for more surely inducing the first notch portion 112-1 and the second notch portion 112-2 to gradually rupture in proportion to the internal pressure. As shown in FIG. 4, when the change in the notch depth forms a linear form of a linear function, when the rupture of the first notch portion 112-1 and the second notch portion 112-2 is started, there is a possibility of further rupture beyond the desired level due to inertia. Therefore, FIG. 5 is an embodiment for effectively preventing such excessive rupture. At the initial stage of rupture, the left and right corners of the first notch portion 112-1 and the second notch portion 112-2 easily rupture, but when the rupture progresses toward the center, excessive rupture is prevented by the rapid thickening of the thickness.

[0053] FIG. 6 shows the configuration of the first notch portion 112-1 and the second notch portion 112-2 for obtaining the same effect as the embodiment of FIG. 5, and the change in the notch depth forms a discontinuous stepped form. Since the notch depth changes discontinuously and the rupture strength is discontinuous for each step, the possibility of excessive rupture is greatly reduced by the stepwise rupture of the first notch portion 112-1 and the second notch portion 112-2 in response to the increase in pressure.

[0054] (Third Embodiment) FIG. 9 is a drawing showing an example in which the two-way bending device 100 of the present invention is mounted on the secondary battery 200. The secondary battery 200 includes a battery case 210 having a space for accommodating the electrode assembly 220, and one or more two-way bending devices 100 can be mounted on at least one surface (the upper surface in the drawing) of the battery case 210.

[0055] The two-way bending device 100 is airtightly mounted so that the first notch portion 112-1 and the second notch portion 112-2 are externally exposed with respect to the bending hole 212 formed in the battery case 210. That is, the first notch portion 112-1 and the second notch portion 112-2 are entirely externally observable so that there is no obstruction or interference when the first notch portion 112-1 and the second notch portion 112-2 rupture to form a butterfly shape as shown in FIG. 3.

[0056] And the mounting part 120 for fixing the two-way bending device to the battery case 210 can be fixed by welding to the battery case 210 in a state aligned with the bending hole 212 formed through the battery case 210. Alternatively, in the embodiment shown in FIG. 9, the mounting part 120 protrudes in a well form so as to form an edge in the form of a wall 122 with respect to the rupture disk 110, but the side wall 122 of the mounting part 120 can be inserted into and coupled to the bending hole 212. Of course, it is also possible to strengthen the fixing strength by welding the side wall 122 of the mounting part 120 to the bending hole 212.

[0057] And, as shown in the partially enlarged view of FIG. 9, the mounting part 120 can include a support frame 124 that crosses the center where the first notch part 112-1 and the second notch part 112-2 are separately arranged from each other. The support frame 124 will surely prevent the ruptures of the first notch part 112-1 and the second notch part 112-2 from affecting each other. As a result, when the ruptured first notch part 112-1 and the second notch part 112-2 form a butterfly shape, it becomes more certain that high-temperature gas, dust, etc. are discharged in both side directions.

[0058] The present invention has been described in more detail with reference to the drawings and embodiments. However, the configurations described in the drawings or embodiments described in this specification are only one embodiment of the present invention and do not represent all of the technical ideas of the present invention. Therefore, there can be various equivalents and modifications that can replace these at the time of this application.

Explanation of Reference Numerals

[0059] 100: Two-way bending device 110: Rupture disk 112: Notch part 112-1: First notch part 112-2: Second notch part 120: Mounting part 122: Side wall 124: Support frame 200: Secondary battery 210: Battery case 212: Venting hole 220: Electrode assembly SL: Symmetry line

Claims

1. A rupture disk having a notch portion that ruptures when a pressure exceeding a preset value acts thereon, A mounting portion provided along the edge of the rupture disk, and the notch portion includes a first notch portion formed along the left half corner of the rupture disk and a second notch portion formed along the right half corner of the rupture disk, separated so as not to be connected to the first notch portion, a two-way bending device.

2. The rupture disk ruptures such that the first notch portion and the second notch portion form a butterfly shape when a pressure exceeding a preset value acts thereon, the two-way bending device according to claim 1.

3. The first notch portion and the second notch portion are such that, based on a virtual symmetry line crossing the center where they are separated from each other, the notch depth becomes deeper as the distance from the symmetry line increases, the two-way bending device according to claim 2.

4. The first notch portion and the second notch portion are such that the change in the notch depth forms a linear shape, the two-way bending device according to claim 3.

5. The first notch portion and the second notch portion are such that the rate of change of the notch depth increases as the distance from the symmetry line increases, the two-way bending device according to claim 4.

6. The first notch portion and the second notch portion are such that the change in the notch depth forms a discontinuous stepped shape, the two-way bending device according to claim 3.

7. The first notch portion and the second notch portion rupture from the left and right corners with a deeper notch depth in proportion to the magnitude of the pressure exceeding a preset value, the two-way bending device according to claim 3.

8. A battery case having a space for accommodating an electrode assembly, The two-way bending device according to any one of claims 1 to 7, wherein one or more are mounted on at least one surface of the battery case, and a secondary battery.

9. The two-way bending device is airtightly mounted such that the first notch portion and the second notch portion are exposed to the outside with respect to a bending hole formed in the battery case, the secondary battery according to claim 8.

10. The mounting portion is welded and fixed to the battery case in a state aligned with the bending hole, the secondary battery according to claim 9.

11. The mounting portion The secondary battery according to claim 9, comprising an edge in the form of a wall inserted into the bending hole.

12. The mounting part The secondary battery according to claim 11, comprising a support frame that crosses the center where the first notch part and the second notch part are separately arranged from each other.

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