Cylindrical secondary battery

Abstract

The present invention comprises: a cylindrical can in which an electrode assembly is accommodated, and which has a beading part formed to protrude inward from a portion positioned at the upper side of the accommodated electrode assembly; and a top cap which has a disk shape and which is seated on the beading part of the can, wherein the upper end of the can is bent to encompass the top surface of the top cap while the top cap is seated on the beading part, and thus a crimping part is formed, the crimping part having notches recessed in a predetermined depth so as to be divided into a plurality of division parts. In the present invention including the described features, the notch is formed with a relatively smaller thickness in the crimping part so that, when the pressure inside the can increases, rupturing can be induced along the portion in which the notch is formed. Therefore, since the crimping part can be deformed at lower pressure, the top cap can be more quickly separated from the can. Thus, a conventional problem of bursting of a can side wall portion can be resolved.

Description

Cylindrical secondary battery

[0001] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0005616, filed January 12, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a cylindrical secondary battery, and more particularly, to a cylindrical secondary battery capable of preventing a top cap attached to the top of the can from being quickly detached and causing an explosion of the side wall of the can when gas is generated inside the can and the internal pressure increases.

[0003]

[0004] Secondary batteries, widely used in various digital devices and transportation systems such as automobiles, are characterized by their ability to be repeatedly charged and discharged. Furthermore, research and development is continuously being conducted to increase efficiency and enhance safety.

[0005] Secondary batteries can be classified in various ways depending on the shape of the battery case or the material of the electrode assembly, but when classified by the shape of the battery case, cylindrical, square, and pouch types are the most widely manufactured.

[0006] Among these, the cylindrical secondary battery has a structure in which an electrode assembly (30) is built into the interior of a hollow cylindrical can (10) having an open top and a closed bottom, and a top cap (20) is fixedly connected to the top of the can (10).

[0007] Referring to Fig. 1a, which shows a cross-sectional view (figure below) and a plan view (figure above) of a conventional cylindrical secondary battery, the can (10) is connected to the electrode assembly (30) at the bottom surface through a negative electrode tab (not shown), and the top cap (5) is connected to the positive electrode (not shown) of the electrode assembly (30).

[0008] The can (10) above has a side wall (in the shape of a pipe) that extends upward along the circumference from the bottom surface. When the electrode assembly (30) is mounted, the upper end of the side wall of the can (10) is processed to form a beading portion (11) that protrudes inward.

[0009] And, the top cap (20) is placed on top of the beading portion (11). And, a certain portion of the upper part of the can (10) above the beading portion (11) is bent (crimped) in a direction that is gathered toward the center to form a crimping portion (12) and fix the top cap (20).

[0010] Meanwhile, in order to prevent explosion and ignition, the top cap (20) is configured by combining a cap (21) used as a positive terminal, a PTC (Positive Temperature Coefficient Thermistor) (22) whose resistance increases when overcurrent occurs and reduces the amount of current, a vent part (23) that breaks to discharge gas when the internal gas pressure increases, a current interrupting device (CID) (26) that is connected to the positive tab (31) and breaks when the internal pressure increases to cut off the current, and gaskets (24, 25) for insulating between each part.

[0011] However, when gas is generated inside the can (10), if the vent part (23) is not properly ruptured or a large amount of gas or an internal explosion suddenly occurs, the side wall of the can (10) may rupture, causing a chain explosion of neighboring cylindrical secondary batteries.

[0012] That is, referring to Fig. 1b, which illustrates an explosion caused by a rupture of the side wall of the can, when the electrolyte vaporizes inside the can (10) and a large amount of gas (that the vent cannot handle) is generated and the internal pressure increases or an internal explosion occurs, the top cap (20) receives an upward force due to the internal pressure, and accordingly, the crimping portion (12) receives a force in the direction of unfolding. However, if the crimping portion (12) is not unfolded properly and the top cap (20) is not detached, the pressure inside the can (10) may cause the side wall of the can (10) to rupture.

[0013] Typically, cylindrical secondary batteries are manufactured by lining up tens to thousands of batteries to form battery modules or packs. Therefore, if a side rupture occurs in a single cylindrical secondary battery, the explosive energy can be transmitted to neighboring batteries, potentially triggering a chain reaction of explosions.

[0014] That is, as shown in Fig. 1c, which shows the crimping portion (12) being spread and the top cap (20) being separated, even if the internal pressure rises and an internal explosion occurs, if the top cap (20) is separated from the can (10) before it leads to the rupture of the side wall of the can (10), the pressure inside the can can be quickly reduced, and (because the direction of the explosion in which the gas is ejected is changed) a chain reaction of explosions of neighboring secondary batteries can be prevented, thereby relatively reducing damage.

[0015]

[0016] Therefore, the main purpose of the present invention is to provide a cylindrical secondary battery in which the top cap can be quickly detached from the crimping portion before the side wall surface explodes (ruptures) when the internal pressure of the can increases in order to prevent a chain explosion of neighboring secondary batteries, thereby solving the conventional problems described above.

[0017]

[0018] In order to achieve the above object, the present invention provides a cylindrical secondary battery, comprising: a cylindrical can having an electrode assembly therein and a beading portion formed to protrude inwardly at a portion positioned on an upper side of the accommodated electrode assembly; and a top cap having a disc-shaped shape and seated on the beading portion of the can; wherein, in a state where the top cap is seated on the beading portion, an upper end of the can is bent to surround an upper surface of the top cap to form a crimping portion, and a notch formed with a predetermined depth is formed in the crimping portion so as to be divided into a plurality of divided portions. That is, the crimping portion is divided into a region where a notch is formed and a region where it is not formed, and the divided portions refer to regions where no notch is formed in the crimping portion.

[0019] The above notch is formed in a straight shape, but is positioned in a direction away from the center of the top cap when extended in the longitudinal direction.

[0020] The outer circumference of the above crimping portion forms an outer boundary line, the inner circumference forms an inner boundary line, and the notch is formed to form an oblique line between the outer boundary line and the inner boundary line.

[0021] The angle formed between the imaginary line connecting the center of the top cap to the point on the inner boundary where the notch is formed and the notch is formed in a range of 40° to 60°.

[0022] In the above crimping portion, 8 to 14 notches are formed.

[0023] At this time, the notches are arranged in multiple pieces with a constant interval between them. Alternatively, they may be arranged so as to form irregular intervals. That is, the notches are arranged in multiple pieces with a constant interval between them, but the intervals at one location may be formed to be of different sizes from those at another location.

[0024] The width of the notch is formed smaller than the length of the notch. In an embodiment provided by the present invention, the width of the notch is formed to be 0.5 mm to 1.5 mm, and the length of the notch is formed to be 2 mm to 4 mm. In addition, a plurality of the notches are formed with the same width and length.

[0025] In addition, the thickness of the portion where the notch is formed is formed in a range of 20% to 50% of the thickness of the divided portion. For example, if the thickness of the divided portion is 1 mm, the thickness of the portion where the notch is formed can be formed in a range of 0.2 mm to 0.5 mm.

[0026] In addition, a plurality of cylindrical secondary batteries having the above technical characteristics can be electrically connected to each other to manufacture a secondary battery module.

[0027]

[0028] The present invention, having the aforementioned configuration, has a notch formed in the crimping portion with a relatively thin thickness. When pressure inside the can increases, a fracture can be induced along the notch. Consequently, the crimping portion can deform under a lower pressure, allowing the top cap to be separated from the can more quickly. This eliminates the conventional problem of the can's sidewall rupturing.

[0029] In addition, in the present invention, since the adjacent divided portions are not completely separated (since the notches are formed and connected to each other by the remaining portion), the reduction in the fastening force of the top cap can be prevented in a normal state where the pressure inside the can is low.

[0030] The above notch is formed in a straight shape, but is arranged in a direction away from the center of the top cap when extended in the longitudinal direction (i.e., arranged to have a helical shape), so that when a fracture occurs at the part where the notch is formed and one of the split portions is spread out (to become vertical), the adjacent split portions can also be spread out in a chain.

[0031] At this time, the above notches are arranged in multiple pieces at a constant interval from each other to fix the top cap with uniform pressure.

[0032]

[0033] Figure 1a is a drawing showing a cross-sectional view (bottom drawing) and a plan view (top drawing) viewed from above of a conventional cylindrical secondary battery.

[0034] Figure 1b is a drawing showing an explosion caused by a rupture of the side wall of the can.

[0035] Figure 1c is a drawing showing the crimping portion being spread out and the top cap being separated.

[0036] FIG. 2 is a drawing showing a cross-sectional view (bottom drawing) and a plan view (top drawing) viewed from above of a cylindrical secondary battery provided as a first embodiment of the present invention.

[0037] Figure 3 is an enlarged drawing of the portion where the crimping part is located in Figure 2.

[0038] Figure 4 is a drawing showing a cross-sectional view of the ZZ' portion in Figure 3.

[0039] FIG. 5 is a drawing showing a second embodiment of the present invention, in which the spacing between adjacent notches is formed differently.

[0040]

[0041] Hereinafter, the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily practice the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0042] In order to clearly explain the present invention, parts that are not related to the description are omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0043] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0044] The present invention relates to a cylindrical secondary battery in which, when the pressure inside the can (10) increases, the crimping portion (12) is quickly vertically spread (deformed) to induce the detachment of the top cap (20), thereby solving the problem of a conventional structure in which the side wall of the can (10) may be ruptured, thereby causing a chain reaction of explosions (of neighboring cylindrical secondary batteries). Hereinafter, embodiments of the present invention will be described in more detail with reference to the attached drawings.

[0045]

[0046] First embodiment

[0047]

[0048] The cylindrical secondary battery provided in this embodiment is configured to include a can (10) and a top cap (20), and is characterized in that a notch (14) is formed in a fine shape to a predetermined depth in a crimping portion (12) formed on the top of the can (10).

[0049] FIG. 2 is a drawing showing a cross-sectional view (below) and a plan view (above) viewed from above of a cylindrical secondary battery provided as a first embodiment of the present invention, FIG. 3 is an enlarged drawing showing a portion where a crimping portion (12) is located in FIG. 2, and FIG. 4 is a drawing showing a cross-sectional view of a ZZ' portion in FIG. 3.

[0050] Referring to the drawings, the can (10) is formed in a hollow cylindrical shape, with the upper side being open and the lower side being closed at the bottom surface.

[0051] That is, the can (10) is provided with a side wall surface formed that extends upward along the circumference from the bottom surface. Then, when the negative tab (not shown) of the electrode assembly (30) is mounted inside the can (10) while being welded to the bottom surface of the can, the upper end of the side wall surface of the can (10) is processed to form a beading portion (11) so as to protrude inward.

[0052] And, the top cap (20) is mounted on the beading portion (11). The top cap (20) has an overall disc-shaped shape and is provided in a size that can be mounted on the beading portion (11) of the can (10).

[0053] The above top cap (20) includes safety devices to prevent explosion and ignition in addition to the cap (21) used as the positive terminal. The safety devices may include a PTC (Positive Temperature Coefficient Thermistor) (22) that increases resistance and reduces current when overcurrent occurs, a vent part (23) that ruptures to discharge gas when internal gas pressure increases, and a current interrupting device (CID) (26) that is connected to the positive tab (31) and ruptures when internal pressure increases to cut off current. In addition, gaskets (24, 25) are additionally included to insulate between each component.

[0054] And, a certain portion of the upper part of the can (10) above the beading part (11) is folded (crimped) to wrap in a direction that gathers toward the center, forming a crimping part (12) and fixing the top cap (20).

[0055] In addition, as shown in the drawing, in this embodiment, a notch (14) is formed at a predetermined depth so as to be divided into a plurality of divided portions (13) in the crimping portion (12). That is, the crimping portion (13) is divided into an area where the notch (14) is formed and an area where the notch (14) is not formed, and the divided portions (13) mean areas in the crimping portion (12) where the notch (14) is not formed.

[0056] The above notch (14) is formed in a straight shape, but is arranged in a direction that deviates from the center (C) of the top cap (20) when extended in the longitudinal direction. As shown in Fig. 3, the notch (14) is formed to form an oblique line between the outer boundary line (o) that becomes the outer circumference of the crimping portion (12) and the inner boundary line (i) that becomes the inner circumference.

[0057] And, referring to Fig. 4, which shows an enlarged cross-sectional view of a portion where a notch (14) is formed, the crimping portion (12) presses on the gasket (24), which is an insulator, to fix and restrain the top cap (20), and is divided into a plurality of individual division portions (13) by the notch (14).

[0058] Here, the notch (14) refers to a portion dug to a certain depth in the crimping portion (12), and the remaining portion (14a: i.e., the portion where the notch is formed) in the area where the notch (14) is formed connects the neighboring split portions (13). That is, this portion (14a) connects the neighboring split portions (13) and serves to bind the neighboring split portions (13) when the crimping portion (12) fixes the top cap (20).

[0059] In this embodiment, the thickness of the portion (14a) where the notch (14) is formed is formed in a range of 20% to 50% of the thickness of the divided portion (13) (i.e., the length from top to bottom based on FIG. 4). For example, if the thickness of the divided portion (13) is 1 mm, the thickness of the portion (14a) where the notch (14) is formed can be formed within a range of 0.2 mm to 0.5 mm, and if the thickness of the divided portion (13) is 0.5 mm, the thickness of the portion (14a) where the notch is formed can be formed within a range of 0.1 mm to 0.25 mm.

[0060] In this embodiment, the angle (θ) formed between the imaginary line (x) connecting the center (C) of the top cap (20) to the point of the inner boundary line (i) where the notch (14) is formed and the notch is formed in a range of 40° to 60°, and 8 to 14 notches (14) are formed in the crimping portion (12).

[0061] And, the width (w) of the notch (14) is formed smaller than the length (l) of the notch (14). Although, the width and size of the notch (14) can be adjusted depending on the size of the can (10), in the embodiment provided by the present invention, the width (w) of the notch (14) is formed to be 0.5 mm to 1.5 mm, and the length (l) of the notch (14) is formed to be 2 mm to 4 mm.

[0062] In addition, when deformation of one split section (13) occurs (when it is expanded), the neighboring split sections (13) are deformed in a chain by applying the same pressure, so that the plurality of notches (14) are formed with the same width (w) and length (l).

[0063] And, at this time, the above notches (14) are arranged in multiple numbers with a certain interval (g) between them.

[0064]

[0065] Second embodiment

[0066]

[0067] Meanwhile, in the cylindrical secondary battery provided in the first embodiment above, the notches (14) can be modified in various ways.

[0068] For example, as shown in FIG. 5, which illustrates a second embodiment of the present invention in which the gaps (g1, g2) between adjacent notches (14) are arranged to be different, a plurality of the notches (14) are arranged with gaps between them, but the gap (g1) at one location and the gap (g2) at another location may be formed to have different sizes.

[0069] Alternatively, only some of the notches (14) among the plurality of notches (14) may be configured to have a larger width or a different angle of inclination.

[0070] In addition, it is also possible to configure the notches (14) to be more densely packed in a specific area so that the top cap (20) is induced to deviate in a specific direction depending on the position and direction in which the can (10) is placed, or not to form the notches (14) in a specific area.

[0071]

[0072] In addition, in the present invention, a plurality of cylindrical secondary batteries having the technical features provided in the first embodiment and / or the second embodiment above can be electrically connected to each other to manufacture a secondary battery module.

[0073] The present invention, having the configuration described above, has a notch (14) formed to have a relatively thin thickness in the crimping portion (12), so that when the pressure inside the can increases, a break can be induced along the portion (14a) where the notch (14) is formed. Accordingly, the crimping portion (12) can be deformed at a lower pressure, so that the top cap (20) can be separated from the can (10) more quickly. Accordingly, the conventional problem of the side wall of the can (10) being ruptured can be solved.

[0074] In addition, in the present invention, since the neighboring divided parts (13) are not completely separated (since the notches are formed and connected to each other by the remaining part), the decrease in the fastening force of the top cap (20) can be prevented in a normal state where the pressure inside the can (10) is low.

[0075] The above notch (14) is formed in a straight shape, but is arranged in a direction that deviates from the center (C) of the top cap (20) when extended in the longitudinal direction (i.e., arranged to have a helical shape), so that when a fracture occurs at the portion (14a) where the notch (14) is formed and one of the split portions (13) is opened, the adjacent split portions (13) can also be opened in a chain.

[0076] At this time, the above notches (14) are arranged in multiple numbers at a constant interval from each other to fix the top cap with uniform pressure.

[0077] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various embodiments are possible within the scope equivalent to the technical idea of ​​the present invention and the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0078] [Explanation of symbols]

[0079] 10: Can

[0080] 11: Bidding Department

[0081] 12: Crimping section

[0082] 13: Division

[0083] 14: Notch

[0084] 14a: Part where the notch is formed

[0085] 20: Top cap

[0086] 30: Electrode assembly

Claims

1. A cylindrical can that accommodates an electrode assembly inside and has a beaded portion formed on the upper side of the accommodated electrode assembly so as to protrude inward; and A top cap having a disc-shaped shape and configured to be seated on the beading portion of the can; With the top cap secured to the beading portion, the upper end of the can is bent to wrap around the upper surface of the top cap to form a crimping portion. A cylindrical secondary battery in which the crimping portion is formed with a fine notch of a predetermined depth so as to be divided into a plurality of split portions.

2. In paragraph 1, A cylindrical secondary battery in which the above notch is formed in a straight shape, but is arranged in a direction that deviates from the center of the top cap when extended in the longitudinal direction.

3. In paragraph 2, The outer circumference of the above crimping portion forms an outer boundary line, and the inner circumference forms an inner boundary line. The above notch is formed to form an oblique line between the outer boundary line and the inner boundary line, and is a cylindrical secondary battery.

4. In paragraph 3, A cylindrical secondary battery, wherein an angle formed between an imaginary line connecting the center of the top cap to the point of the inner boundary line where the notch is formed and the notch is formed in a range of 40° to 60°.

5. In paragraph 3 A cylindrical secondary battery having 8 to 14 notches formed in the crimping portion.

6. In paragraph 3 The above notch is a cylindrical secondary battery in which a plurality of notches are arranged at equal intervals from each other.

7. In paragraph 2 A cylindrical secondary battery in which the above notches are arranged in multiple numbers with a gap between them, but the gap at one location is formed with a different size from the gap at another location.

8. In paragraph 2, A cylindrical secondary battery in which the width of the notch is formed smaller than the length of the notch.

9. In paragraph 8, A cylindrical secondary battery in which the width of the notch is formed to be 0.5 mm to 1.5 mm and the length of the notch is formed to be 2 mm to 4 mm.

10. In paragraph 8, A cylindrical secondary battery in which a plurality of the above notches are formed with the same width and length.

11. In paragraph 1, A cylindrical secondary battery in which the thickness of the portion where the notch is formed is formed in a range of 20% to 50% of the thickness of the divided portion.

12. A secondary battery module in which a plurality of cylindrical secondary batteries according to any one of claims 1 to 11 are electrically connected to each other.

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