Cylindrical secondary battery including top cap

Abstract

A cylindrical secondary battery according to an embodiment of the present invention includes a cylindrical can configured to accommodate an electrode assembly, and a top cap configured to cover an open top of the cylindrical can. The top cap includes a first conductive portion, a second conductive portion disposed below the first conductive portion and electrically connected to the electrode assembly, and a middle layer including a third conductive portion disposed between the first conductive portion and the second conductive portion, contacting the first conductive portion and the second conductive portion and melting at a predetermined temperature or higher to release the contact between the first conductive portion and the second conductive portion. The middle layer may include a gasket portion disposed between the first conductive portion and the second conductive portion, and forming a penetration region between the third conductive portion and the third conductive portion when the third conductive portion is disposed to penetrate the third conductive portion.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0127432 filed on October 5, 2022 and Korean Patent Application No. 10-2023-0128587 filed on September 25, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a cylindrical secondary battery including a top cap. [Background technology]

[0003] To solve the problems of environmental pollution caused by the use of fossil fuels and the energy resource shortage caused by the depletion of fossil fuels, research and development into power generation based on environmentally friendly energy sources is being conducted. In particular, research into rechargeable secondary batteries is being actively conducted, and various aspects of secondary batteries, such as their materials, structure, processes, and stability, are being studied.

[0004] Regarding the structure of secondary batteries, secondary batteries are classified into pouch-type, prismatic-type, cylindrical-type, etc. depending on the shape of the battery case that houses the electrode assembly. Cylindrical-type secondary batteries incorporate a jelly-roll-type electrode assembly in a wound form. The internal electrode assembly may be electrically connected to a cylindrical can and a top cap via electrode tabs. To ensure the stability of cylindrical-type secondary batteries, the top cap may be provided with a structure that can cut off current when an overcurrent flows.

[0005] According to conventional technology, in order to ensure the stability of cylindrical secondary batteries, a current interrupting member that is separated when an overcurrent flows is used, or the electrode tab is cut off when an overcurrent flows to interrupt the current. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a top cap capable of simply and effectively interrupting overcurrent in a cylindrical battery, and a cylindrical secondary battery including the top cap. [Means for solving the problem]

[0007] A cylindrical secondary battery according to an embodiment of the present invention includes a cylindrical can configured to accommodate an electrode assembly, and a top cap configured to cover an open top of the cylindrical can. The top cap includes a first conductive portion, a second conductive portion disposed below the first conductive portion and electrically connected to the electrode assembly, and a middle layer including a third conductive portion disposed between the first conductive portion and the second conductive portion, contacting the first conductive portion and the second conductive portion and melting at a predetermined temperature or higher to release the contact between the first conductive portion and the second conductive portion. The middle layer may include a gasket portion disposed between the first conductive portion and the second conductive portion, and forming a penetration region between the third conductive portion and the third conductive portion when the third conductive portion is disposed to penetrate the third conductive portion.

[0008] The middle layer portion includes the gasket portion disposed to enclose the third conductive portion at a distance from the third conductive portion, and the third conductive portion may melt and decrease in height when heated to a predetermined temperature or higher, thereby releasing the contact.

[0009] The third conductive portion may have a melting point lower than the melting points of the first conductive portion and the second conductive portion.

[0010] The third conductive portion may overlap the first conductive portion and the second conductive portion when viewed from above.

[0011] The cylindrical can includes a placement portion formed on the inner surface on which the middle layer is placed, and the top cap can cover the open top by placing the middle layer on the placement portion.

[0012] The periphery of the middle layer portion may be circular when viewed from above, and the third conductive portion may be circular and strip-shaped when viewed from above.

[0013] The middle layer portion includes the gasket portion in which the circular band-shaped through-hole region is formed, and the third conductive portion can be arranged so as to contact a portion of the gasket portion corresponding to the small radius of the through-hole region when viewed from above.

[0014] The first conductive part and the second conductive part may be electrically connected via the third conductive part when the temperature is below a predetermined temperature, and the electrical connection may be cut off when the third conductive part melts at a temperature above a predetermined temperature.

[0015] The third conductive portion may be provided so as to be in surface contact with each of the first conductive portion and the second conductive portion.

[0016] A top cap according to an embodiment of the present invention covers an upper portion of a cylindrical secondary battery having an electrode assembly accommodated therein, and may include a first conductive portion, a second conductive portion disposed below the first conductive portion and electrically connected to the electrode assembly, a third conductive portion disposed between the first conductive portion and the second conductive portion, contacting the first conductive portion and the second conductive portion, and melting at a predetermined temperature or higher to release the contact between the first conductive portion and the second conductive portion, and a middle layer portion including a gasket portion disposed to penetrate the third conductive portion and forming a penetration region between the third conductive portion and the third conductive portion.

[0017] The middle layer portion includes the gasket portion including a portion spaced apart from the third conductive portion and configured to enclose the third conductive portion, and the third conductive portion may melt and decrease in height when heated to a predetermined temperature or higher, thereby releasing the contact.

[0018] The third conductive portion may have a melting point lower than the melting points of the first conductive portion and the second conductive portion.

[0019] The middle layer includes the gasket portion that is provided so that the third conductive portion is coupled to the outer surface thereof, and the third conductive portion may melt and decrease in height when heated to a predetermined temperature or higher, thereby releasing the contact. [Effects of the Invention]

[0020] According to a preferred embodiment of the present invention, overcurrent can be cut off simply and effectively. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a perspective view showing a cylindrical secondary battery according to an embodiment of the present invention; [Figure 2] 1 is a plan view showing a cylindrical secondary battery according to an embodiment of the present invention; [Figure 3] 1 is a side cross-sectional view showing a cylindrical secondary battery according to an embodiment of the present invention. [Figure 4] FIG. 2 is an exploded perspective view showing a top cap according to an embodiment of the present invention. [Figure 5] 1 is a side cross-sectional view showing a top cap in a state where current is not interrupted according to an embodiment of the present invention; [Figure 6] 1 is a side cross-sectional view showing a top cap in a state where a current is cut off according to an embodiment of the present invention; [Figure 7] FIG. 10 is a side cross-sectional view showing a top cap according to another embodiment of the present invention. [Figure 8] FIG. 10 is a side cross-sectional view showing a top cap according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022]

[0030] The present invention will now be described in detail with reference to the accompanying drawings, in which:

[0031] A preferred embodiment of the present invention will be described in detail so that those skilled in the art can easily implement the present invention; however, the present invention may be embodied in various different forms and should not be construed as being limited to the following embodiments.

[0023] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the description or related known technologies that may obscure the gist of the present invention are omitted, and when referring to components in each drawing in this specification, the same or similar reference symbols are used throughout the specification to refer to the same or similar components.

[0024] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best explain their invention.

[0025] FIG. 1 is a perspective view showing a cylindrical secondary battery 1 according to one embodiment of the present invention, FIG. 2 is a plan view showing a cylindrical secondary battery 1 according to one embodiment of the present invention, and FIG. 3 is a side cross-sectional view showing a cylindrical secondary battery 1 according to one embodiment of the present invention.

[0026] The cylindrical secondary battery 1 may be a secondary battery having a cylindrical shape that can be repeatedly charged and discharged. The cylindrical secondary battery 1 may house an electrode assembly 4 therein, and the electrode assembly 4 may be electrically connected to the outside via a conductive member (e.g., a top cap).

[0027] The cylindrical secondary battery 1 may include a top cap 2. The top cap 2 may cover the top of the cylindrical secondary battery 1. For example, the top cap 2 may form an outer edge at the top of the cylindrical secondary battery 1. The top cap 2 may include a conductive member. For example, when an electrode assembly 4 is housed inside the cylindrical secondary battery 1, the electrode assembly 4 may be electrically connected to the outside via the top cap 2 including the conductive member.

[0028] The cylindrical secondary battery 1 may include a cylindrical can 3. The cylindrical can 3 may be provided to house an electrode assembly 4. For example, an internal space having a shape corresponding to the shape of the electrode assembly 4 may be formed. The electrode assembly 4 may be a jelly-roll type electrode assembly in a wound form, but the form or shape of the electrode assembly may not be particularly limited.

[0029] The top cap 2 may cover the open top of the cylindrical can 3. For example, the cylindrical can 3 may be provided with an open top. The electrode assembly 4 may enter and exit through the open top of the cylindrical can 3. The top cap 2 may be placed on the cylindrical can 3 to cover the open top of the cylindrical can 3. For example, the top cap 2 may be placed on a mounting portion 3-1 of the cylindrical can 3. The mounting portion 3-1 may be provided on an upper portion of the inner surface of the cylindrical can 3 and may have a shape that protrudes inward so that the top cap 2 can be placed thereon. The structure and shape of the mounting portion 3-1 may not be particularly limited as long as the top cap 2 can be placed on the cylindrical can 3.

[0030] The top cap 2 may include a first conductive portion 10. The first conductive portion 10 may include a conductive member. For example, the first conductive portion 10 may be a metal plate.

[0031] The top cap 2 may include a second conductive member 20. The second conductive member 20 may include a conductive member. For example, the second conductive member 20 may be a metal plate. The second conductive member 20 may be disposed below the first conductive member 10. For example, the second conductive member 20 may be disposed below the first conductive member 10, with a middle layer 30 (described below) sandwiched between the first conductive member 10 and the second conductive member 20. The second conductive member 20 may be electrically connected to the electrode assembly 4. For example, the second conductive member 20 may be electrically connected to the electrode assembly 4 by contacting the electrode assembly 4.

[0032] The top cap 2 may include an intermediate layer 30. For example, the intermediate layer 30 may be disposed between the first conductive portion 10 and the second conductive portion 20. When viewed from above, the intermediate layer 30 may have portions that overlap with the first conductive portion 10 and the second conductive portion 20.

[0033] The middle layer 30 may include a third conductive portion 31. The third conductive portion 31 may be disposed between the first conductive portion 10 and the second conductive portion 20 and in contact with the first conductive portion 10 and the second conductive portion 20, respectively. The third conductive portion 31 may electrically connect the first conductive portion 10 and the second conductive portion 20 by contacting the first conductive portion 10 and the second conductive portion 20. The third conductive portion 31 may abut and make surface contact with portions of the first conductive portion 10 and the second conductive portion 20. The third conductive portion 31 may have the same height as (or a corresponding height to) the gasket portion 32. For example, the third conductive portion 31 may have the same height as the gasket portion 32 because it is disposed in the gasket portion 32 while in contact with the first conductive portion 10 and the second conductive portion 20 to electrically connect the first conductive portion 10 and the second conductive portion 20.

[0034] The middle layer 30 may include a gasket portion 32. The gasket portion 32 may be disposed between the first conductive portion 10 and the second conductive portion 20. The gasket portion 32 may also be configured to surround the third conductive portion 31. For example, the gasket portion 32 may be disposed to surround the third conductive portion 31 with a gap therebetween. Alternatively, the third conductive portion 31 may be disposed to penetrate the gasket portion 32. Alternatively, the gasket portion 32 may include a portion disposed to surround the third conductive portion 31 with a gap therebetween.

[0035] A through region 33 may be formed in the middle layer 30. For example, the through region 33 may be a region between the gasket portion 32 and the third conductive portion 31 when the third conductive portion 31 is disposed so as to penetrate the gasket portion 32. In other words, the through region 33 may be a concept of a space formed between the third conductive portion 31 and the gasket portion 32 when the gasket portion 32 is disposed between the first conductive portion 10 and the second conductive portion 20. Alternatively, the through region 33 may be a region formed by the gap between the gasket portion 32 and the third conductive portion 31.

[0036] Although the above description has been given assuming that the through region 33 is formed in the middle layer 30, the present invention is not limited thereto. For example, even if the through region 33 is not formed, the intended object and effect of the present invention can be achieved if a predetermined region (or space) is provided so that the molten third conductive portion 31 can flow when the third conductive portion 31 is melted. In other words, when the third conductive portion 31 is melted, the molten third conductive portion 31 flows into the predetermined region (or space), and the third conductive portion 31 can be released from contact with the first conductive portion 10 or the second conductive portion 20, thereby cutting off the electrical connection.

[0037] The top cap 2 can cover the open top of the cylindrical can 3 by placing the middle layer 30 on the placing portion 3-1. For example, the middle layer 30 of the top cap 2 can be placed on the placing portion 3-1. The placing portion 3-1 can be provided so that the middle layer 30 is placed on the inner surface of the cylindrical can 3. More specifically, the gasket portion 32 of the middle layer 30 can be placed on the placing portion 3-1 of the cylindrical can 3 to cover (or seal) the open top of the cylindrical can 3.

[0038] Fig. 4 is an exploded perspective view showing a top cap 2 according to an embodiment of the present invention, Fig. 5 is a side cross-sectional view showing a top cap 2 in a state where current is not cut off according to an embodiment of the present invention, and Fig. 6 is a side cross-sectional view showing a top cap 2 in a state where current is cut off according to an embodiment of the present invention. The above description can be applied equally or similarly to this embodiment.

[0039] The third conductive portion 31 may overlap the first conductive portion 10 and the second conductive portion 20 when viewed from above. For example, the third conductive portion 31 may be disposed between the first conductive portion 10 and the second conductive portion 20 to electrically connect the first conductive portion 10 and the second conductive portion 20, and may include portions that overlap the first conductive portion 10 and the second conductive portion 20 when viewed from above.

[0040] When viewed from above, the periphery of the middle layer 30 may be circular, and the third conductive portion 31 may be circular and strip-shaped. For example, the periphery of the middle layer 30 may correspond to the periphery of the gasket portion 32, and the periphery may be circular so that it is placed on the cylindrical can 3. The third conductive portion 31 may be circular and strip-shaped, and the third conductive portion 31 may be coupled to the inner surface of the gasket portion 32 to form a circular and strip-shaped through-hole region 33. Alternatively, the third conductive portion 31 may be disposed so as to contact a portion of the gasket portion 32 that corresponds to the small radius of the through-hole region 33. The volume of the through-hole region 33 may be designed in advance. The shape of the third conductive portion 31 is not limited to a circular and strip-shaped shape, and various shapes may be realized depending on the design.

[0041] The third conductive portion 31 may have a melting point lower than the melting points of the first conductive portion 10 and the second conductive portion 20. For example, when an overcurrent flows through the first conductive portion 10, the second conductive portion 20, and the third conductive portion 31, the third conductive portion 31 may melt, but the first conductive portion 10 and the second conductive portion 20 may not melt. As described above, only the third conductive portion 31 melts due to the overcurrent, and the gasket portion 32 provides support between the first conductive portion 10 and the second conductive portion 20, which may be advantageous in terms of structural stability. Even when the third conductive portion 31 melts due to the overcurrent, the shape of the gasket portion 32 is maintained, so that the overall outer shape and position of the middle layer portion 30 may be maintained unchanged.

[0042] The melting of the third conductive portion 31 may result in the loss of contact with the first conductive portion 10 or the second conductive portion 20. For example, if the temperature of the third conductive portion 31 is equal to or higher than a predetermined temperature due to an overcurrent, the third conductive portion 31 melts and its height decreases, thereby breaking contact with the first conductive portion 10 or the second conductive portion 20. In other words, if the temperature of the third conductive portion 31 is equal to or higher than a predetermined temperature and the third conductive portion 31 melts, the electrical connection between the first conductive portion 10 and the second conductive portion 20 may be cut off. As another example, if no overcurrent flows and the temperature of the third conductive portion 31 is lower than a predetermined temperature, the third conductive portion 31 may not melt, thereby maintaining the contact. In other words, if the third conductive portion 31 is lower than a predetermined temperature and therefore not melted, the electrical connection between the first conductive portion 10 and the second conductive portion 20 may be maintained via the third conductive portion 31.

[0043] As described above, when an overcurrent flows, the third conductive part 31 melts, thereby releasing contact with the first conductive part 10 and the second conductive part 20 and cutting off the electrical connection, thereby blocking the overcurrent simply and effectively.

[0044] 7 is a side cross-sectional view showing a top cap 2a according to another embodiment of the present invention. The above description can be applied in the same or similar manner to this embodiment.

[0045] The top cap 2a may include a third conductive portion 31a. A through-hole region 31a may be formed between the third conductive portion 31a and the gasket portion 32a. As shown in FIG. 7, the through-hole region 31a may be formed at a position different from the through-hole region 31 in FIG. 3 or 5.

[0046] As shown in FIG. 7, the third conductive portion 31a is arranged to have a radius larger than the radius of the third conductive portion 31, so that the size of the contact area with the first conductive portion 10a and the second conductive portion 20a can also be increased.

[0047] When the contact area between the third conductive part 31a and the first and second conductive parts 10a and 20a is increased, current can flow more effectively.

[0048] 8 is a side cross-sectional view showing a top cap 2b according to yet another embodiment of the present invention. The above description can be applied in the same or similar manner to this embodiment.

[0049] The top cap 2b can cover the open top of the cylindrical can 3. For example, the second conductive part 20b of the top cap 2b can be coupled and fixed to the inner surface of the cylindrical can 3. In this case, the open top of the cylindrical can 3 can be covered even if the above-mentioned middle layer parts 30, 30a are not placed on the placement part 3-1 of the cylindrical can 3.

[0050] The third conductive portion 32b may be disposed so as to surround at least a portion of the outer surface of the gasket portion 32b. For example, the third conductive portion 31b may be disposed so as to surround the outer surface of the gasket portion 32b and may be in contact with the first conductive portion 10b and the second conductive portion 20b.

[0051] As described above, the volume of the gasket portion 32b can be reduced, which is advantageous for production, and since the second conductive portion 20b is fixed to the inner surface of the cylindrical can 3, a space in which the third conductive portion 31b can flow when melted can be secured without a separate process. In addition, the size of the third conductive portion 31b can be adjusted by design to adjust the degree of current flow.

[0052] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible within the technical spirit of the present invention and the scope of the claims set forth below by a person having ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0053] 1 Cylindrical secondary battery 2, 2a, 2b top cap 3 Cylindrical cans 3-1 Placement section 4 Electrode assembly 10, 10a, 10b First conductive part 20, 20a, 20b Second conductive part 30, 30a, 30b Middle level section 31, 31a, 31b Third conductive part 32, 32a, 32b Gasket part 33, 33a penetration area

Claims

1. a cylindrical can provided to house the electrode assembly; a top cap provided to cover the open top of the cylindrical can; The top cap is A first conductive portion; a second conductive portion disposed below the first conductive portion and electrically connected to the electrode assembly; an intermediate layer portion including a third conductive portion disposed between the first conductive portion and the second conductive portion, in contact with the first conductive portion and the second conductive portion, and melting at a predetermined temperature or higher, thereby releasing the contact between the first conductive portion and the second conductive portion; The middle layer is A cylindrical secondary battery including a gasket portion disposed between the first conductive portion and the second conductive portion, and configured so that the third conductive portion is inserted therethrough, thereby forming a penetration region between the gasket portion and the third conductive portion.

2. The middle layer is the gasket portion is provided to surround the third conducting portion at a distance from the third conducting portion, The third conductive portion is The cylindrical secondary battery according to claim 1 , wherein the contact is released when the temperature is equal to or higher than a predetermined temperature by melting and decreasing in height.

3. The third conductive portion is The cylindrical secondary battery according to claim 1 , wherein the first conductive portion and the second conductive portion have a melting point lower than that of the first conductive portion and the second conductive portion.

4. The third conductive portion is The cylindrical secondary battery according to claim 1 , wherein the first conductive portion and the second conductive portion overlap when viewed from above.

5. The cylindrical can is a placement portion formed on an inner surface so that the middle layer portion can be placed thereon; The top cap is The cylindrical secondary battery according to claim 1 , wherein the middle layer covers the open top portion when placed on the placement portion.

6. The periphery of the middle layer is circular when viewed from above, The cylindrical secondary battery according to claim 1 , wherein the third conductive portion has a circular band shape when viewed from above.

7. The middle layer is the gasket portion having the circular band-shaped through-area formed therein; The third conductive portion is The cylindrical secondary battery according to claim 1 , wherein the gasket portion is disposed so as to contact a portion of the gasket portion corresponding to a small radius of the penetration region when viewed from above.

8. The first conductive portion and the second conductive portion are When the temperature is lower than a predetermined temperature, the third conductive part is electrically connected to the first conductive part, and The cylindrical secondary battery of claim 1 , wherein the electrical connection is interrupted when the third conductive part melts at a predetermined temperature or higher.

9. The cylindrical secondary battery according to claim 1 , wherein the third conductive portion is provided so as to be in surface contact with each of the first conductive portion and the second conductive portion.

10. A top cap for covering an upper portion of a cylindrical secondary battery in which an electrode assembly is accommodated, A first conductive portion; a second conductive portion disposed below the first conductive portion and electrically connected to the electrode assembly; a third conductive portion that is disposed between the first conductive portion and the second conductive portion, that contacts the first conductive portion and the second conductive portion, and that melts when it reaches a predetermined temperature or higher, thereby releasing the contact between the first conductive portion and the second conductive portion; and an intermediate layer portion that includes a gasket portion that is disposed so that the third conductive portion is penetrated, and that forms a penetration region between the third conductive portion and the third conductive portion.

11. The middle layer is the gasket portion includes a portion spaced apart from the third conducting portion and configured to surround the third conducting portion, The third conductive portion is The top cap of claim 10, wherein the contact is released when the temperature is equal to or higher than a predetermined temperature by melting and decreasing in height.

12. The third conductive portion is The top cap of claim 10 having a melting point lower than melting points of the first conductive portion and the second conductive portion.

13. The middle layer is the third conductive portion includes the gasket portion provided to be coupled to an outer surface thereof, The third conductive portion is The top cap according to claim 10 or 12, wherein when the temperature is equal to or higher than a predetermined temperature, the top cap melts and decreases in height, thereby releasing the contact.

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