Cylindrical secondary battery including top cover

Abstract

A cylindrical secondary battery according to one embodiment of the present invention comprises: a cylindrical can adapted to receive an electrode assembly; and a top cap adapted to cover the open top of the cylindrical can wherein the top cap comprises an intermediate layer comprising: a first conductive portion; a second conductive portion disposed below the first conductive portion and electrically connected to the electrode assembly; and a third conductive portion that is provided between the first conductive portion and the second conductive portion, is in contact with the first conductive portion and the second conductive portion, and melts to release contact between the first conductive portion and the second conductive portion when a temperature is greater than or equal to a predetermined temperature, and the intermediate layer may include a pad portion disposed between the first conductive portion and the second conductive portion and forming a through region with the third conductive portion in a case where the third conductive portion is disposed to be penetrated.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to 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, which are hereby incorporated by reference in their entirety. Technical Field

[0003] The present invention relates to a cylindrical type secondary battery including a top cover. Background Art

[0004] In order to solve the environmental pollution problems caused by the use of fossil fuels and solve the energy problems caused by the depletion of fossil fuels, research and development of power production based on eco-friendly energy have been carried out. In particular, research on secondary batteries that can be repeatedly charged has been actively carried out, and research on various aspects of secondary batteries such as materials, structures, processes and stability has been carried out.

[0005] Regarding the structure of the secondary battery, the secondary battery can be classified into a pouch type, a prismatic type, a cylindrical type, etc., according to the shape of the battery box for accommodating the electrode assembly. A wound type electrode assembly having a wound shape is embedded in a cylindrical secondary battery. The electrode assembly inside the cylindrical secondary battery can be electrically connected to the cylindrical can and the top cover through an electrode tab. In terms of the stability of the cylindrical secondary battery, the top cover can be provided with a structure capable of cutting off the current when an overcurrent flows through.

[0006] According to the related art, in order to ensure the stability of the cylindrical type secondary battery, a current interruption member configured to be separated when an overcurrent flows is used, or when an overcurrent flows, an electrode tab is broken to cut off the current. Summary of the invention

[0007] Technical issues

[0008] An object of the present invention for solving the above-mentioned problems is to provide a top cover capable of simply and effectively cutting off an overcurrent of a cylindrical battery, and a cylindrical secondary battery including the top cover.

[0009] Technical Solution

[0010] A cylindrical secondary battery according to an embodiment of the present invention may include: a cylindrical can configured to accommodate an electrode assembly; and a top cover configured to cover an open upper portion of the cylindrical can. The top cover may include: a first conductive portion; a second conductive portion configured below the first conductive portion and electrically connected to the electrode assembly; and an intermediate layer portion, the intermediate layer portion including a third conductive portion, the third conductive portion configured between the first conductive portion and the second conductive portion to contact each of the first conductive portion and the second conductive portion, wherein when the temperature of the third conductive portion is a predetermined temperature or higher, the third conductive portion melts so that the contact between the third conductive portion and the first conductive portion and the second conductive portion is released. The intermediate layer portion may include a liner portion, the liner portion being configured between the first conductive portion and the second conductive portion, and forming a through region between the third conductive portion and the third conductive portion when the third conductive portion is configured to be penetrated.

[0011] The middle layer portion may include a pad portion which is arranged to surround the third conductive portion while being spaced apart from the third conductive portion, and when the temperature of the third conductive portion is a predetermined temperature or higher, the third conductive portion may melt to reduce the height of the third conductive portion so that the contact is released.

[0012] The melting point of the third conductive portion may be lower than the melting point of each of the first conductive portion and the second conductive portion.

[0013] When viewed from above, the third conductive portion may overlap each of the first conductive portion and the second conductive portion.

[0014] The cylindrical can may include a seating portion provided on an inner surface of the cylindrical can such that the middle layer portion is seated on the seating portion, and as the middle layer portion is seated on the seating portion, the top cover may cover the opened upper portion.

[0015] When viewed from above, an edge of the intermediate layer portion may have a circular shape, and when viewed from above, the third conductive portion may have a ring shape.

[0016] The intermediate layer portion may include a pad portion in which a through region having a ring shape is defined, and the third conductive portion may be disposed to contact a portion of the pad portion corresponding to a small radius of the through region when viewed from above.

[0017] The first conductive portion and the second conductive portion may be electrically connected to each other through the third conductive portion when the temperature of the third conductive portion is lower than a predetermined temperature, and the electrical connection may be cut off when the third conductive portion reaches a predetermined temperature or higher to melt.

[0018] The third conductive portion may be provided in surface contact with each of the first conductive portion and the second conductive portion.

[0019] A top cover according to an embodiment of the present invention can cover an upper portion of a cylindrical secondary battery configured so that an electrode assembly is accommodated therein, and the top cover includes: a first conductive portion; a second conductive portion, which is disposed below the first conductive portion and is electrically connected to the electrode assembly; and an intermediate layer portion, which includes: a third conductive portion, which is disposed between the first conductive portion and the second conductive portion to contact each of the first conductive portion and the second conductive portion, wherein when the temperature of the third conductive portion is a predetermined temperature or higher, the third conductive portion melts so that the contact between the third conductive portion and the first conductive portion and the second conductive portion is released; and a pad portion, which forms a through-region between the pad portion and the third conductive portion when the third conductive portion is configured to be penetrated.

[0020] The middle layer portion may include a pad portion which is arranged to surround the third conductive portion while being spaced apart from the third conductive portion, and when the temperature of the third conductive portion is a predetermined temperature or higher, the third conductive portion may melt to reduce the height of the third conductive portion so that the contact is released.

[0021] The melting point of the third conductive portion may be lower than the melting point of each of the first conductive portion and the second conductive portion.

[0022] The middle layer portion may include a pad portion configured so that the third conductive portion is connected to the outer surface of the pad portion, and when the temperature of the third conductive portion is a predetermined temperature or higher, the third conductive portion may melt to reduce the height of the third conductive portion so that the contact is released.

[0023] Beneficial effects

[0024] According to the preferred embodiments of the present invention, overcurrent can be cut off simply and effectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a perspective view illustrating a cylindrical secondary battery according to an embodiment of the present invention.

[0026] Figure 2 is a plan view illustrating a cylindrical type secondary battery according to an embodiment of the present invention.

[0027] Figure 3 is a side sectional view illustrating a cylindrical type secondary battery according to an embodiment of the present invention.

[0028] Figure 4is an exploded perspective view illustrating a top cover according to an embodiment of the present invention.

[0029] Figure 5 is a side cross-sectional view illustrating a top cover in a state where current is not cut off according to an embodiment of the present invention.

[0030] Figure 6 is a side cross-sectional view illustrating a top cover in a state where current is cut off according to an embodiment of the present invention.

[0031] Figure 7 is a side sectional view illustrating a top cover according to another embodiment of the present invention.

[0032] Figure 8 is a side sectional view illustrating a top cover according to still another embodiment of the present invention. DETAILED DESCRIPTION

[0033] Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention belongs can easily implement the present invention. However, the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein.

[0034] In order to clearly describe the present invention, parts that are irrelevant to the description or detailed description of related well-known technologies that may unnecessarily obscure the subject matter of the present invention will be excluded. Throughout the specification, like reference numerals refer to like elements.

[0035] In addition, the terms or words used in the present specification and claims should not be restrictively interpreted as ordinary meanings or dictionary-based meanings, but should be interpreted as meanings and concepts consistent with the scope of the present invention based on the principle that the inventor can appropriately define the concepts of the terms to best describe and interpret his or her invention.

[0036] Figure 1 is a perspective view illustrating a cylindrical secondary battery 1 according to an embodiment of the present invention. Figure 2 is a plan view illustrating a cylindrical type secondary battery 1 according to an embodiment of the present invention. Figure 3 is a side cross-sectional view illustrating a cylindrical type secondary battery 1 according to an embodiment of the present invention.

[0037] The cylindrical secondary battery 1 may be a secondary battery that can be repeatedly charged and discharged and has a cylindrical shape. The cylindrical secondary battery 1 may contain an electrode assembly 4 inside, and the electrode assembly 4 may be electrically connected to the outside through a conductive member (eg, a top cover).

[0038] The cylindrical secondary battery 1 may include a top cover 2. The top cover 2 may cover the upper portion of the cylindrical secondary battery 1. For example, the top cover 2 may provide an external appearance at the upper portion of the cylindrical secondary battery 1. The top cover 2 may include a conductive member. For example, when the electrode assembly 4 is accommodated inside the cylindrical secondary battery 1, the electrode assembly 4 may be electrically connected to the outside through the top cover 2 including the conductive member.

[0039] The cylindrical secondary battery 1 may include a cylindrical can 3. The cylindrical can 3 may be configured so that the electrode assembly 4 is accommodated therein. For example, an internal space having a shape corresponding to the shape of the electrode assembly 4 may be defined. The electrode assembly 4 may be a wound-type electrode assembly having a wound shape, but the shape or configuration of the electrode assembly may not be particularly limited.

[0040] The top cover 2 may cover the open upper portion of the cylindrical tank 3. For example, the cylindrical tank 3 may be arranged so that the upper portion of the cylindrical tank is open. The electrode assembly 4 may be pulled in and out through the open upper portion of the cylindrical tank 3. The top cover 2 may be seated on the cylindrical tank 3 so as to cover the open upper portion of the cylindrical tank 3. For example, the top cover 2 may be seated on the seating portion 3-1 of the cylindrical tank 3. The seating portion 3-1 may be arranged on the upper portion of the inner surface of the cylindrical tank 3 and have a shape that protrudes inwardly so that the top cover 2 sits thereon. The structure or shape of the seating portion 3-1 is not particularly limited as long as the top cover 2 can be seated on the cylindrical tank 3.

[0041] The top cover 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.

[0042] The top cover 2 may include a second conductive portion 20. The second conductive portion 20 may include a conductive member. For example, the second conductive portion 20 may be a metal plate. The second conductive portion 20 may be disposed below the first conductive portion 10. For example, the second conductive portion 20 may be disposed below the first conductive portion 10, wherein the intermediate layer portion 30 to be described later is located between the second conductive portion 20 and the first conductive portion 10. The second conductive portion 20 may be electrically connected to the electrode assembly 4. For example, the second conductive portion 20 may contact the electrode assembly 4 to be electrically connected to the electrode assembly 4.

[0043] The top cover 2 may include an intermediate layer portion 30. For example, the intermediate layer portion 30 may be provided between the first conductive portion 10 and the second conductive portion 20. The intermediate layer portion 30 may have a portion overlapping each of the first conductive portion 10 and the second conductive portion 20 when viewed from above.

[0044] The middle layer portion 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 to contact each of the first conductive portion 10 and the second conductive portion 20. Since the third conductive portion 31 contacts each of the first conductive portion 10 and the second conductive portion 20, the third conductive portion 31 may electrically connect the first conductive portion 10 to the second conductive portion 20. The third conductive portion 31 may contact a portion of each of the first conductive portion 10 and the second conductive portion 20 so as to be in surface contact with each of the first conductive portion 10 and the second conductive portion 20. The third conductive portion 31 may have the same (or corresponding) height as the pad portion 32. For example, since the third conductive portion 31 is disposed in the pad portion 32 while contacting each of the first conductive portion 10 and the second conductive portion 20 to electrically connect the first conductive portion 10 to the second conductive portion 20, the third conductive portion 31 may have the same height as the pad portion 32.

[0045] The intermediate layer portion 30 may include a pad portion 32. The pad portion 32 may be provided between the first conductive portion 10 and the second conductive portion 20. In addition, the pad portion 32 may have a shape surrounding the third conductive portion 31. For example, the pad portion 32 may be provided to surround the third conductive portion 31 while being spaced apart from the third conductive portion 31. In other words, the third conductive portion 31 may be provided to have a shape passing through the pad portion 32. Alternatively, the pad portion 32 may include a portion provided to surround the third conductive portion 31 while being spaced apart from the third conductive portion 31.

[0046] A through region 33 may be defined in the intermediate layer portion 30. For example, the through region 33 may be a region located between the pad portion 30 and the third conductive portion 31 in a state where the third conductive portion 31 is disposed to pass through the pad portion 32. In other words, the through region 33 may be a concept of a space defined between the third conductive portion 31 and the pad portion 30 when the pad 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 defined by a gap between the pad portion 32 and the third conductive portion 31.

[0047] Although, as described above, the through region 33 is described as being defined in the middle layer portion 30, the middle layer portion 30 is not limited thereto. For example, even if the middle layer portion 30 is not penetrated, the intended purpose and effect of the present invention can be achieved simply by ensuring a predetermined region (or space) that is configured such that when the third conductive portion 31 melts, the molten third conductive portion 31 flows therein. In other words, when the third conductive portion 31 melts, the molten third conductive portion 31 can flow into the predetermined region (or space) to release the contact between the third conductive portion 31 and the first conductive portion 10 or the second conductive portion 20. Therefore, the electrical connection can be cut off.

[0048] Since the middle layer part 30 is seated on the seat part 3-1, the top cover 2 can cover the open upper part of the cylindrical tank 3. For example, the middle layer part 30 of the top cover 2 can be seated on the seat part 3-1. The seat part 3-1 can be provided on the inner surface of the cylindrical tank 3 so that the middle layer part 30 is seated on the inner surface. Specifically, since the cushion part 32 of the middle layer part 30 is seated on the seat part 3-1 of the cylindrical tank 3, the open upper part of the cylindrical tank 3 can be covered (or sealed).

[0049] Figure 4 1 is an exploded perspective view illustrating a top cover 2 according to an embodiment of the present invention. Figure 5 : is a side cross-sectional view illustrating the top cover 2 in a state where the current is not cut off according to the embodiment of the present invention. Figure 6 2 is a side sectional view illustrating a top cover 2 in a state where current is cut off according to an embodiment of the present invention. The same or similar description as the aforementioned description can also be applied to this embodiment.

[0050] When viewed from above, the third conductive portion 31 may overlap each of the first conductive portion 10 and the second conductive portion 20. For example, the third conductive portion 31 may be provided between the first conductive portion 10 and the second conductive portion 20 so as to electrically connect the first conductive portion 10 to the second conductive portion 20, and the third conductive portion 31 may include a portion overlapping each of the first conductive portion 10 and the second conductive portion 20 when viewed from above.

[0051] When viewed from above, the edge of the middle layer portion 30 may have a circular shape, and the third conductive portion 31 may have an annular shape. For example, the edge of the middle layer portion 30 may correspond to the edge of the cushion portion 32, and the middle layer portion 30 may have an edge with a circular shape so as to sit on the cylindrical tank 3. The third conductive portion 31 may have an annular shape, and since the third conductive portion 31 is coupled to the inner surface of the cushion portion 32, a through-region 33 having an annular shape may be defined. In other words, the third conductive portion 31 may be arranged to contact a portion of the cushion portion 32 corresponding to a small radius of the through-region 33. The volume of the through-region 33 may be pre-designed. The shape of the third conductive portion 31 described above is not limited to the annular shape, and the third conductive portion 31 may be implemented in various forms according to the design.

[0052] The melting point of the third conductive part 31 may be lower than the melting point of each of the first conductive part 10 and the second conductive part 20. For example, when an overcurrent flows through the first conductive part 10, the second conductive part 20 and the third conductive part 31, the third conductive part 31 may melt, but the first conductive part 10 and the second conductive part 20 may not melt. As described above, only the third conductive part 31 may melt due to the overcurrent, and the pad part 32 may be provided between the first conductive part 10 and the second conductive part 20 to support the first conductive part 10 and the second conductive part 20. Therefore, this may be advantageous in terms of structural stability. Even when the third conductive part 31 melts due to the overcurrent, the shape of the pad part 32 may be maintained so that the overall external shape and position of the intermediate layer part 30 remain unchanged.

[0053] Since the third conductive portion 31 melts, the contact between the third conductive portion 31 and the first conductive portion 10 or the second conductive portion 20 may be released. For example, when the temperature of the third conductive portion 31 is higher than a predetermined temperature due to an overcurrent, the third conductive portion 31 may melt to reduce its height so that the contact between the third conductive portion 31 and the first conductive portion 10 or the second conductive portion 20 is released. In other words, when the temperature of the third conductive portion 31 is higher than a predetermined temperature and thus 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. For another example, when no overcurrent flows and thus the temperature of the third conductive portion 31 is lower than a predetermined temperature, the third conductive portion 31 may not melt and the contact may be maintained. In other words, when the temperature of the third conductive portion 31 is lower than a predetermined temperature and thus the third conductive portion 31 does not melt, the electrical connection between the first conductive portion 10 and the second conductive portion 20 may be maintained by the third conductive portion 31.

[0054] As described above, when an overcurrent flows, the third conductive portion 31 is melted so that the contact between the third conductive portion 31 and the first conductive portion 10 and the second conductive portion 20 is released to cut off the electrical connection between the third conductive portion 31 and the first conductive portion 10 and the second conductive portion 20. Therefore, the overcurrent can be simply and effectively cut off.

[0055] Figure 7 2 is a side sectional view illustrating a top cover 2a according to another embodiment of the present invention. The same or similar description as the above description can also be applied to this embodiment.

[0056] The top cover 2a may include a third conductive portion 31a. A through region 31a may be defined between the third conductive portion 31a and the pad portion 32a. Figure 7 As shown in FIG. , the through region 31a may be defined as Figure 3 or Figure 5 The penetration area 31 is at different positions.

[0057] like Figure 7 As illustrated in FIG. 1 , since the third conductive portion 31 a is provided to have a radius greater than that of the third conductive portion 31 , a contact area with each of the first conductive portion 10 a and the second conductive portion 20 a may be increased.

[0058] When the contact area between the third conductive portion 31 a and each of the first conductive portion 10 a and the second conductive portion 20 a increases, current may flow more efficiently.

[0059] Figure 8 2 is a side sectional view illustrating a top cover 2b according to another embodiment of the present invention. The same or similar description as the above description can also be applied to this embodiment.

[0060] The top cover 2b may cover the opened upper portion of the cylindrical tank 3. For example, the second conductive portion 20b of the top cover 2b may be coupled and fixed to the inner surface of the cylindrical tank 3. In this case, even when the above-mentioned intermediate layer portion 30 or 30a is not seated on the seating portion 3-1 of the cylindrical tank 3, the opened upper portion of the cylindrical tank 3 may be covered.

[0061] The third conductive portion 31b may be disposed to surround at least a portion of the outer surface of the pad portion 32b. For example, the third conductive portion 31b may be disposed to surround the outer surface of the pad portion 32b and to contact each of the first conductive portion 10b and the second conductive portion 20b.

[0062] As described above, the volume of the gasket portion 32b can be reduced to lead to advantages in 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 the third conductive portion 31b is melted can be ensured without requiring a separate process. In addition, the size of the third conductive portion 31b can be adjusted according to the design to adjust the degree of current conduction.

[0063] Although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereto and may be implemented in various ways by a person skilled in the art to which the present invention pertains within the technical concept of the present invention and equivalents of the appended claims.

[0064] [reference numerals list]

[0065] 1: Cylindrical secondary battery

[0066] 2, 2a, 2b: Top cover

[0067] 3: Cylindrical tank

[0068] 3-1: Seating part

[0069] 4: Electrode assembly

[0070] 10, 10a, 10b: first conductive portion 20, 20a, 20b: second conductive portion 30, 30a, 30b: intermediate layer portion 31, 31a, 31b: third conductive portion 32, 32a, 32b: pad portion 33, 33a: through region

Claims

1. A cylindrical secondary battery, comprising: a cylindrical can configured to house the electrode assembly; as well as a top cover, the top cover being arranged to cover the open upper portion of the cylindrical tank, Wherein, the top cover comprises: a first conductive portion; a second conductive portion disposed below the first conductive portion and electrically connected to the electrode assembly; and an intermediate layer portion including a third conductive portion provided between the first conductive portion and the second conductive portion to be in contact with each of the first conductive portion and the second conductive portion, wherein when a temperature of the third conductive portion is a predetermined temperature or higher, the third conductive portion melts so that contact between the third conductive portion and the first conductive portion and the second conductive portion is released, The intermediate layer portion includes a pad portion, which is disposed between the first conductive portion and the second conductive portion, and forms a through region with the third conductive portion when the third conductive portion is configured to be penetrated.

2. The cylindrical secondary battery according to claim 1, wherein: The intermediate layer portion includes the pad portion configured to surround the third conductive portion while being spaced apart from the third conductive portion, and When the temperature of the third conductive portion is the predetermined temperature or higher, the third conductive portion melts to reduce the height of the third conductive portion, so that the contact is released.

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

4. The cylindrical secondary battery according to claim 1, wherein When viewed from above, the third conductive portion overlaps each of the first conductive portion and the second conductive portion.

5. The cylindrical secondary battery according to claim 1, wherein The cylindrical tank includes a seating portion provided on an inner surface of the cylindrical tank such that the intermediate layer portion is seated on the seating portion, and Wherein, as the middle layer portion is seated on the seating portion, the top cover covers the opened upper portion.

6. The cylindrical secondary battery according to claim 1, wherein When viewed from above, the edge of the intermediate layer portion has a rounded shape, and The third conductive portion has a ring shape when viewed from above.

7. The cylindrical secondary battery according to claim 1, wherein The intermediate layer portion includes the pad portion in which a through region having an annular shape is defined, and The third conductive portion is disposed so as to be in contact with a portion of the pad portion corresponding to a small radius of the through region when viewed from above.

8. The cylindrical secondary battery according to claim 1, wherein The first conductive portion and the second conductive portion are electrically connected to each other through the third conductive portion when the temperature of the third conductive portion is lower than the predetermined temperature, and The electrical connection is cut off when the third conductive portion reaches the predetermined temperature or higher to melt.

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

10. A top cover configured to cover an upper portion of a cylindrical secondary battery disposed such that an electrode assembly is accommodated therein, The top cover comprises: a first conductive portion; a second conductive portion disposed below the first conductive portion and electrically connected to the electrode assembly; and The middle layer, Wherein, the middle layer part comprises: a third conductive portion provided between the first conductive portion and the second conductive portion to be in contact with each of the first conductive portion and the second conductive portion, wherein when a temperature of the third conductive portion is a predetermined temperature or more, the third conductive portion melts so that contact between the third conductive portion and the first conductive portion and the second conductive portion is released; and The pad portion forms a through region with the third conductive portion when the third conductive portion is configured to penetrate.

11. The top cover according to claim 10, wherein: The intermediate layer portion includes the pad portion, the pad portion including a portion configured to surround the third conductive portion while being spaced apart from the third conductive portion, and When the temperature of the third conductive portion is the predetermined temperature or higher, the third conductive portion melts to reduce the height of the third conductive portion, so that the contact is released.

12. The top cover according to claim 10, wherein: The third conductive portion has a melting point lower than a melting point of each of the first conductive portion and the second conductive portion.

13. The top cover according to claim 10, wherein: The intermediate layer portion includes the pad portion, the pad portion being arranged such that the third conductive portion is coupled to an outer surface of the pad portion, and When the temperature of the third conductive portion is the predetermined temperature or higher, the third conductive portion melts to reduce the height of the third conductive portion, so that the contact is released.

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