Bidirectional venting 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 that improves 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 direction, and a secondary battery including the same.

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

Background Art

[0003] Unlike primary batteries, secondary batteries are rechargeable and have been extensively researched and developed in recent years due to their potential for miniaturization and high capacity. With the increasing technological 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 installed 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 smoothly performed, the temperature rise causes an increase in current, and the increase in current causes a positive feedback chain reaction that again causes a temperature rise, and as a result, it reaches a catastrophic state of thermal runaway.

[0006] When a secondary battery experiences thermal runaway, both temperature and pressure rise. If these temperatures and pressures exceed the battery's heat and pressure resistance limits, the battery's structure will eventually collapse. A collapsed battery allows a large amount of air to enter its interior, causing a fire or explosion that can become uncontrollable and spread to the surrounding area, resulting in significant damage.

[0007] To prevent structural collapse of such rechargeable batteries, venting devices are often provided in rechargeable batteries, especially cylindrical and prismatic batteries. A venting device is a type of safety valve that releases pressure by rupturing when the internal pressure of the rechargeable battery exceeds a certain level.

[0008] However, most current venting devices are designed to expel dangerous elements such as high-temperature gas, flames, and heated particles directly upwards. When secondary batteries are used in electric vehicles, such venting devices may pose safety problems by spraying dangerous elements towards the driver or passengers. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The present invention aims to provide a venting device and a secondary battery including the same that improve safety by guiding the discharge direction of dangerous factors such as high-temperature gas, flames, and heated particles ejected from a secondary battery experiencing thermal runaway to both sides away from directly above.

[0010] However, the technical problems that the present invention aims to solve are not limited to those described above, and other problems not mentioned can be clearly understood by an ordinary person of the art from the description of the invention below. [Means for solving the problem]

[0011] The present invention relates to a bidirectional venting device, which in one example includes a rupture disc having a notch that ruptures when pressure exceeding a preset value is applied, and a mounting portion provided along the edge of the rupture disc, wherein the notch includes a first notch formed along the left half corner of the rupture disc and a second notch formed along the right half corner of the rupture disc, separated from the first notch so as not to be connected to it.

[0012] When pressure exceeding a preset value is applied to the rupture disc, the first and second notches rupture in 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 away from a hypothetical line of symmetry that crosses a central area separated from each other.

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

[0015] Furthermore, the rate of change of the notch depth in the first and second notches may increase as they move away from the line of symmetry.

[0016] Alternatively, as another example, the first notch and the second notch may form a staircase shape with discontinuous changes in the notch depth.

[0017] As a result, the first and second notches may begin to rupture from the left and right corners, where the notch depth is deeper, in proportion to the magnitude of the pressure exceeding a preset value.

[0018] On the other hand, the present invention provides a secondary battery comprising a battery case having a space for housing an electrode assembly, and the above-mentioned bidirectional venting device, one or more of which are mounted on at least one surface of the battery case.

[0019] The bidirectional venting device described above is airtightly mounted to the battery case such that the first notch and the second notch are exposed to the outside through the venting holes formed in the battery case.

[0020] The mounting portion can be welded and fixed to the battery case while aligned with the venting holes.

[0021] Alternatively, the mounting portion may have a wall-shaped edge that is inserted into the venting hole.

[0022] Furthermore, the mounting portion may include a support frame that crosses the center between the first notch portion and the second notch portion, which are separated from each other. [Effects of the Invention]

[0023] According to the bidirectional venting device of the present invention, which has the above configuration, notches that rupture when pressure exceeding a set standard is applied are formed separately from each other along the edges of the left and right halves of the rupture disc. As a result, when the rupture disc ruptures, the first and second notches rupture in a butterfly shape, causing hazardous factors such as high-temperature gas, flames, and heated particles to be discharged to both sides rather than directly above the venting device. Consequently, when applied to medium- and large-sized secondary batteries for automobiles, the venting device of the present invention can improve safety by ejecting hazardous factors to the sides rather than directly above the driver or passengers.

[0024] In addition, in the bi-directional bending device of the present invention, the notch depth of the notch portion can be formed deeper as it approaches 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 the 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 bi-directional 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] It is a drawing showing an embodiment of the bi-directional bending device according to the present invention. [Figure 2] It is a cross-sectional view cut along the line "A - A" of FIG. 1. [Figure 3] It is a drawing showing a bi-directional bending device in a state where the first notch portion and the second notch portion are each ruptured. [Figure 4] It is a drawing showing the structures of the first notch portion and the second notch portion in a bi-directional bending device according to another embodiment of the present invention. [Figure 5] It is a drawing showing the structures of the first notch portion and the second notch portion in a bi-directional bending device according to another embodiment of the present invention. [Figure 6]This drawing shows the structure of the first notch and the second notch in a bidirectional venting device according to another embodiment of the present invention. [Figure 7] This diagram shows a state where the degree of opening of the first notch and the second notch are different from each other. [Figure 8] This diagram shows a state where the degree of opening of the first notch and the second notch are different from each other. [Figure 9] This drawing shows an example of how the bidirectional venting device of the present invention is attached to a secondary battery. [Modes for carrying out the invention]

[0028] The present invention can be modified in various ways and may have a variety of embodiments; therefore, specific embodiments are described in detail below.

[0029] However, this is not intended to limit the present invention to any particular embodiment, but rather should be understood to include all modifications, equivalents, or substitutions that fall within the spirit and technical scope of the present invention.

[0030] In the present invention, terms such as "includes" and "have" are intended to specify the presence of features, numbers, stages, operations, components, parts, or combinations thereof as described in the specification, and do not preemptively exclude the presence or possibility of adding one or more other features, numbers, stages, operations, components, parts, or combinations thereof.

[0031] Furthermore, in this invention, when a part such as a layer, film, region, or plate is described as being "on top" of another part, this includes not only the case where it is "directly on top" of the other part, but also the case where another part is located in between. Conversely, when a part such as a layer, film, region, or plate is described as being "below" another part, this includes not only the case where it is "directly below" the other part, but also the case where another part is located in between. Also, in this application, being "on top" may include being located not only at the top but also at the bottom.

[0032] The present invention relates to a bidirectional venting device, which in one example includes a rupture disc having a notch that ruptures when pressure exceeding a preset value is applied, and a mounting portion provided along the edge of the rupture disc, wherein the notch includes a first notch formed along the left half corner of the rupture disc and a second notch formed along the right half corner of the rupture disc, separated from the first notch so as not to be connected to it.

[0033] When pressure exceeding a preset value is applied to the rupture disc, the first and second notches rupture in a butterfly shape.

[0034] According to the bidirectional venting device of the present invention having such a configuration, notches that rupture when pressure exceeding a certain level is applied are formed separately from each other along the edges of the left and right halves of the rupture disc. As a result, when the rupture disc ruptures, the first and second notches rupture in a butterfly shape, causing hazardous factors such as high-temperature gas, flames, and heated particles to be discharged to both sides rather than directly above the venting device.

[0035] As a result, when the venting device of the present invention is applied to medium- and large-sized secondary batteries for automobiles, safety can be improved by ejecting hazardous materials to the side rather than directly upward towards the driver or passengers.

[0036] Specific embodiments of the bidirectional venting device 100 and the secondary battery 200 including it according to the present invention will be described in detail below with reference to the attached drawings. For reference, the forward / backward and up / down / left / right directions used in the following description to specify relative positions are for the purpose of aiding the understanding of the invention, and unless otherwise defined, the directions shown in the drawings are used as the reference.

[0037] (First Embodiment) Figure 1 is a drawing showing one embodiment of the bidirectional venting device 100 according to the present invention, and Figure 2 is a cross-sectional view obtained by cutting along the line "AA" in Figure 1.

[0038] The illustrated present invention is a bidirectional venting device 100, comprising a rupture disc 110 having a notch portion 112 that ruptures when pressure exceeding a preset value is applied, and a mounting portion 120 provided along the edge of the rupture disc 110.

[0039] The rupture disc 110 is a thin, plate-like member made of metal, with a notch portion 112 formed on its surface. The bidirectional venting device 100 is attached to the secondary battery 200, but when the internal pressure of the sealed battery case 210 increases, the pressure causes tensile deformation throughout the thin rupture disc 110, causing the weaker notch portion 112 to rupture and relieve the internal pressure of the case 210.

[0040] The mounting portion 120 is the edge portion to which the bidirectional venting device 100 is connected to the case 210 of the secondary battery 200, and also plays a role in structurally supporting the rupture disk 110. The form of the mounting portion 120 can be provided in various ways; for example, it may be a plate-like shape thicker than the rupture disk 110, or it may be a well-like shape with protruding side walls 122 surrounding the rupture disk 110.

[0041] Here, the bidirectional venting device 100 of the present invention comprises a pair of independent notch portions 112-1 and 112-2. 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 that is separated from the first notch portion 112-1 and formed along the right half-corner of the rupture disk 110.

[0042] Referring to Figure 2, the first notch portion 112-1 and the second notch portion 112-2 are separated from each other with respect to a hypothetical line of symmetry SL that crosses approximately the 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 the first notch portion 112-1 and the second notch portion 112-2 are formed by line-shaped notching along the left and right half-corners of the rupture disk 110. Since the first notch portion 112-1 and the second notch portion 112-2 are thinner, they have lower bursting strength than other parts of the rupture disk 110, so when pressure exceeding a specified level is applied, rupture occurs in the rupture disk 110 along the first notch portion 112-1 and the second notch portion 112-2.

[0043] Figure 3 is a diagram showing the bidirectional venting device 100 in a state where the first notch portion 112-1 and the second notch portion 112-2 have ruptured, respectively. As shown in the figure, the rupture occurs along the U-shaped lines of the first notch portion 112-1 and the second notch portion 112-2, and the first notch portion 112-1 and the second notch portion 112-2 are lifted upward by internal pressure, with the central region of the rupture disk 110 separating the first notch portion 112-1 and the second notch portion 112-2 acting as a support. In other words, when a pressure exceeding a preset value acts on the bidirectional venting device 100, the rupture disc 110 ruptures in both directions, with the first notch 112-1 and the second notch 112-2 forming a butterfly shape. As a result, gases and flames ejected from inside the secondary battery 200 equipped with the bidirectional venting device 100 are discharged diagonally to both sides rather than directly upwards.

[0044] (Second Embodiment) Figures 4 to 6 show a second embodiment of the bidirectional venting device 100 of the present invention, and in particular, as shown in Figure 2, cross-sections of the cut surfaces along the first notch portion 112-1 and the second notch portion 112-2.

[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 a virtual symmetry line SL that crosses the center of the rupture disk 110 and is separated from each other. In other words, the notch depth is deepest at the edges of the left and right halves of the rupture disk 110.

[0046] According to this second embodiment, when a pressure exceeding a preset value is applied to the rupture disk 110, the first notch portion 112-1 and the second notch portion 112-2 begin to rupture from the left and right corners with deeper notch depths, in proportion to the magnitude of the applied pressure. In other words, since the rupture strength decreases as the notch depth increases, when a pressure exceeding a standard is applied, the left and right corners with deeper notch depths rupture first.

[0047] Furthermore, if the pressure acting on the rupture disk 110 is sufficient to rupture the thinnest left and right corners of the first notch portion 112-1 and the second notch portion 112-2, but is insufficient to rupture the thicker portions, then the first notch portion 112-1 and the second notch portion 112-2 will not rupture entirely, but only a portion of the left and right corners may rupture. In other words, the second embodiment is configured such that only a portion of the first notch portion 112-1 and the second notch portion 112-2 can rupture, and the degree of opening of the first notch portion 112-1 and the second notch portion 112-2 increases in proportion to the applied pressure.

[0048] According to this second embodiment, as thermal runaway progresses inside the secondary battery 200 equipped with the bidirectional venting device 100, the internal pressure gradually increases. In response to the rising pressure level, the degree of opening of the first notch 112-1 and the second notch 112-2 gradually increases. Therefore, in the initial stages of thermal runaway, the first notch 112-1 and the second notch 112-2 rupture slightly, releasing only a small amount of material in both directions. This suppresses combustion acceleration due to air inflow while simultaneously preventing upward discharge to the greatest extent possible.

[0049] Furthermore, in situations where thermal runaway has progressed to its final stage and rapid pressure release is necessary, the entire first notch section 112-1 and the second notch section 112-2 can rupture to secure the maximum release area. Figures 7 and 8 exemplify two states with different degrees of openness depending on the degree of rupture of the first notch section 112-1 and the second notch section 112-2. The state in Figure 8 is one in which the degree of openness is greater than in Figure 7, and the pressure acting on the rupture disk 110 is even higher, causing the entire first notch section 112-1 and the second notch section 112-2 to rupture and achieve the maximum degree of openness.

[0050] On the other hand, Figures 4 to 6 show two different patterns in which the thickness of the first notch portion 112-1 and the second notch portion 112-2 gradually decreases towards the left and right corners.

[0051] Figures 4 and 5 show embodiments in which the change in notch depth for the first notch portion 112-1 and the second notch portion 112-2 takes a linear form. In the embodiment of Figure 4, the notch depth deepens as a linear function as the distance from the symmetry line SL, which crosses the center where the first notch portion 112-1 and the second notch portion 112-2 are separated on the rupture disk 110. In contrast, in the embodiment of Figure 5, the notch depth changes linearly, but rather as a curve, rather than as a linear function, where the rate of change of the notch depth increases as the distance from the symmetry line SL increases.

[0052] The embodiment in Figure 5 is designed to more reliably induce the gradual rupture of the first notch 112-1 and the second notch 112-2 in proportion to the internal pressure. As shown in Figure 4, if the change in notch depth takes the form of a linear function, when the rupture of the first notch 112-1 and the second notch 112-2 begins, inertia may cause them to rupture beyond the desired level. Therefore, Figure 5 is an embodiment that effectively prevents such excessive rupture, in which the left and right corners of the first notch 112-1 and the second notch 112-2 rupture easily in the initial stages of rupture, but as the rupture progresses toward the center, the thickness increases rapidly, preventing excessive rupture.

[0053] Figure 6 shows the configuration of the first notch section 112-1 and the second notch section 112-2 to obtain the same effect as the embodiment in Figure 5, in which the change in notch depth forms a discontinuous step shape. Since the burst strength is discontinuous at each step of the discontinuously changing notch depth, the possibility of excessive bursting is greatly reduced as the first notch section 112-1 and the second notch section 112-2 burst in stages in response to the increase in pressure.

[0054] (Third embodiment) Figure 9 is a diagram showing an example in which the bidirectional venting device 100 of the present invention is mounted on a secondary battery 200. The secondary battery 200 includes a battery case 210 having a space for housing an electrode assembly 220, and one or more bidirectional venting devices 100 may be mounted on at least one surface (the top surface in the diagram) of the battery case 210.

[0055] The bidirectional venting device 100 is airtightly fitted into the venting hole 212 formed in the battery case 210 such that the first notch portion 112-1 and the second notch portion 112-2 are exposed to the outside. In other words, the first notch portion 112-1 and the second notch portion 112-2 are fully exposed so that they can be observed from the outside, without any obstruction or interference as they rupture and form a butterfly shape as shown in Figure 3.

[0056] The mounting portion 120 for fixing the bidirectional venting device to the battery case 210 can be welded to the battery case 210 while aligned with the venting holes 212 formed through the battery case 210. Alternatively, in the embodiment shown in Figure 9, the mounting portion 120 protrudes in a well shape so as to form a wall 122 edge relative to the rupture disc 110, but the side walls 122 of the mounting portion 120 can be inserted into and joined to the venting holes 212. Of course, the fixing strength can also be strengthened by welding the side walls 122 of the mounting portion 120 to the venting holes 212.

[0057] As shown in the enlarged view of Figure 9, the mounting section 120 may include a support frame 124 that crosses the center where the first notch section 112-1 and the second notch section 112-2 are separated from each other. The support frame 124 reliably prevents the ruptures of the first notch section 112-1 and the second notch section 112-2 from influencing each other, thereby ensuring that the ruptured first notch section 112-1 and the second notch section 112-2 form a butterfly shape, thereby ensuring that high-temperature gas, dust, etc. are discharged in both directions.

[0058] The present invention has been described in more detail above with reference to the drawings and embodiments. However, the configurations described in the drawings or embodiments described herein are merely one embodiment of the present invention and do not represent the entire technical concept of the present invention. Therefore, at the time of filing, there may be various equivalents and modifications that can substitute for them. [Explanation of symbols]

[0059] 100: Bidirectional venting device 110: Rapture Disc 112: Notch section 112-1: First notch section 112-2: Second notch section 120: Mounting part 122: Side wall 124: Support frame 200: Secondary battery 210: Battery case 212: Venting Hall 220: Electrode assembly SL: Line of symmetry

Claims

1. A rupture disc equipped with a notch that bursts when pressure exceeding a preset value is applied, A mounting portion provided along the edge of the rupture disk, Includes, The aforementioned notch portion is, The rupture disk includes a first notch formed along the left half corner and a second notch formed along the right half corner of the rupture disk, separated from the first notch and not connected to it. The first notch portion and the second notch portion are A bidirectional venting device in which the notch depth increases as the distance from a hypothetical line of symmetry crosses the centers of two mutually separated components.

2. The aforementioned rupture disk is The bidirectional venting device according to claim 1, wherein when a pressure exceeding a preset value is applied, the first notch portion and the second notch portion burst in a butterfly shape.

3. The first notch portion and the second notch portion are The bidirectional venting device according to claim 1, wherein the change in the notch depth takes a linear form.

4. The first notch portion and the second notch portion are The bidirectional venting device according to claim 3, wherein the rate of change of the notch depth is greater the further it is from the line of symmetry.

5. The first notch portion and the second notch portion are The bidirectional venting device according to claim 1, wherein the change in the notch depth forms a discontinuous step shape.

6. The first notch portion and the second notch portion are The bidirectional venting device according to claim 1, wherein the device ruptures from the left and right corners with deeper notches in proportion to the magnitude of the pressure exceeding a preset value.

7. A battery case having a space for housing an electrode assembly, A bidirectional venting device according to any one of claims 1 to 6, wherein one or more are mounted on at least one surface of the battery case, Rechargeable batteries, including those mentioned above.

8. The aforementioned bidirectional venting device is, The secondary battery according to claim 7, wherein the first notch and the second notch are airtightly mounted in the battery case such that they are exposed to the outside through venting holes formed in the battery case.

9. The aforementioned mounting portion is The secondary battery according to claim 8, wherein the battery is welded and fixed to the battery case in a state aligned with the venting holes.

10. The aforementioned mounting portion is The secondary battery according to claim 8, further comprising a wall-shaped edge that is inserted into the venting hole.

11. The aforementioned mounting portion is The secondary battery according to claim 10, comprising a support frame that crosses the center between the first notch portion and the second notch portion, which are separated from each other.

Images