Cylindrical Secondary Battery Provided with Flexible Input Portion

Abstract

The present invention relates to a cylindrical secondary battery configured such that a hole is provided in a bottom portion of the cylindrical secondary battery manufactured using a metal can and the hole is hermetically sealed using a flexible material, such as rubber.

Claims

1. A cylindrical secondary battery comprising: a cylindrical can having a circular bottom portion and a cylindrically-shaped outer wall connected to an outer circumference of the bottom portion; a jelly-roll type electrode assembly received in the cylindrical can, the jelly-roll type electrode assembly having a structure in which a positive electrode and a negative electrode are wound in a state in which a separator is interposed between the positive electrode and the negative electrode; and a cap assembly configured to hermetically seal the cylindrical can, wherein a through-hole is formed in a portion of the bottom portion of the cylindrical can, the through-hole being hermetically sealed by a sealing portion.

2. The cylindrical secondary battery according to claim 1, wherein the bottom portion is formed so as to have a curved surface that is concave inwardly of the cylindrical battery.

3. The cylindrical secondary battery according to claim 2, wherein a center of the bottom portion comprises a flat portion.

4. The cylindrical secondary battery according to claim 2, wherein the bottom portion is configured such that a radius of curvature of the concavely curved surface is increased from an outer periphery to a center of the bottom portion.

5. The cylindrical secondary battery according to claim 1, wherein the through-hole is disposed at a central portion of the bottom portion of the cylindrical can and spaced apart from a region of the bottom portion to which a negative electrode tab is welded.

6. The cylindrical secondary battery according to claim 5, wherein the through-hole is circular.

7. The cylindrical secondary battery according to claim 1, wherein the sealing portion is made of a polymer resin.

8. The cylindrical secondary battery according to claim 7, wherein the polymer resin is a thermoplastic polymer resin.

9. The cylindrical secondary battery according to claim 7, wherein the polymer resin is an elastomer.

10. The cylindrical secondary battery according to claim 1, wherein the sealing portion is configured as a plug, a radius of a central portion of which is less than a radius of an outer periphery thereof.

11. The cylindrical secondary battery according to claim 10, wherein the plug is configured such that a projection, a radius of which is gradually increased and is then abruptly decreased, is formed at a portion of the plug configured to be inserted into the cylindrical secondary battery.

12. A method of manufacturing the cylindrical secondary battery according to claim 1, the method comprising: 1) forming the through-hole in the bottom portion of the cylindrical secondary battery; 2) receiving the electrode assembly and assembling the cap assembly; 3) disposing the cylindrical battery assembled in step 2) such that the bottom portion faces upwards; 4) injecting an electrolytic solution through the through-hole and activating the cylindrical battery or initially charging and discharging the cylindrical battery; and 5) hermetically sealing the through-hole using the sealing portion.

13. The method according to claim 12, further comprising injecting an additional electrolytic solution between step 4) and step 5).

14. The method according to claim 12, wherein the hermetically sealing step of step 5) comprises hermetically sealing the through-hole using a plug, a radius of a central portion of which is less than a radius of an outer periphery thereof.

15. The method according to claim 12, wherein the hermetically sealing step of step 5) comprises injecting a thermoplastic polymer resin into the through-hole so as to cover a negative electrode tab region welded to the cylindrical can in order to hermetically seal the through-hole.

Description

DESCRIPTION OF DRAWINGS

[0036] FIG. 1 is a vertical sectional view of a conventional general cylindrical secondary battery.

[0037] FIG. 2 is a sectional view of a cylindrical secondary battery provided with a through-hole according to an embodiment of the present invention and the cylindrical secondary battery in the state in which the through-hole is hermetically sealed.

[0038] FIG. 3 is a sectional view showing the lower parts of three kinds of cylindrical secondary batteries according to the present invention, each of which is provided with a through-hole.

[0039] FIG. 4 is a perspective view of sealing portions according to the present invention.

[0040] FIG. 5 is a view showing an example in which the through-hole according to the present invention is hermetically sealed using a sealing portion.

[0041] FIG. 6 is a schematic view showing a process of assembling a cylindrical secondary battery according to the present invention.

BEST MODE

[0042] Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that the preferred embodiments of the present invention can be easily implemented by a person having ordinary skill in the art to which the present invention pertains. In describing the principle of operation of the preferred embodiments of the present invention in detail, however, a detailed description of known functions and configurations incorporated herein will be omitted when the same may obscure the subject matter of the present invention.

[0043] In addition, the same reference numbers will be used throughout the drawings to refer to parts that perform similar functions or operations. In the case in which one part is said to be connected to another part in the specification, not only may the one part be directly connected to the other part, but also, the one part may be indirectly connected to the other part via a further part. In addition, that a certain element is included does not mean that other elements are excluded, but means that such elements may be further included unless mentioned otherwise.

[0044] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0045] FIG. 1 is a vertical sectional view showing a conventional general cylindrical secondary battery. Referring to FIG. 1, the cylindrical secondary battery 100 is configured such that an electrode assembly 110 is received in a cylindrical can 120, a cap assembly 130 is located at the upper part of the cylindrical can, and the cylindrical secondary battery 100 is hermetically sealed by a crimping gasket 133.

[0046] The cap assembly 130 includes a venting member 132 located at the lower part of a top cap 131 while wrapping the outer circumference of the top cap and a current interrupt member 135 located at the lower part of the venting member 132 while contacting a central portion of the venting member 132. A lower gasket 134 configured to prevent the venting member 132 and the current interrupt member 135 from contacting each other at the portion of the venting member 132 other than the central portion thereof is located at the outer periphery of the current interrupt member 135.

[0047] A positive electrode tab 111 of the electrode assembly 110 is attached to the lower surface of the current interrupt member 135 such that the cap assembly 130 serves as a positive electrode terminal, and a negative electrode tab 112 is coupled to the bottom portion of the cylindrical can 120 by welding.

[0048] FIG. 2 is a sectional view of a cylindrical secondary battery 200 provided with a through-hole according to an embodiment of the present invention and the cylindrical secondary battery 200 in the state in which the through-hole is hermetically sealed.

[0049] Referring to FIG. 2, the cylindrical secondary battery 200 according to the present invention is a cylindrical secondary battery 200 including a cylindrical can 220 constituted by a circular bottom portion and a cylinder-shaped outer wall connected to the outer circumference of the bottom portion, a jelly-roll type electrode assembly 210 is received in the cylindrical can 220, the jelly-roll type electrode assembly having a structure in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are wound, and a cap assembly 230 configured to hermetically seal the cylindrical can 220. A through-hole 250 is formed in a portion of the bottom portion of the cylindrical can 220, and the through-hole 250 is hermetically sealed by a sealing portion 260.

[0050] FIG. 3 is a sectional view showing the lower parts of three kinds of cylindrical secondary batteries according to the present invention, each of which is provided with a through-hole.

[0051] Referring to FIG. 3, the bottom portion of the secondary battery may be flat (the first figure of FIG. 3) or may be formed so as to have a curved surface that is concave inwards, wherein the radius of curvature of the concavely curved surface may be increased from the outer periphery to the center of the bottom portion (the second figure of FIG. 3). Alternatively, a central portion of the bottom portion may include a flat portion (the third figure of FIG. 3).

[0052] It can be seen from FIGS. 2 and 3 that the through-hole 250 is disposed at the central portion of the bottom portion of the cylindrical can 220 excluding a region of the bottom portion to which a negative electrode tab 212 is welded.

[0053] FIG. 4 is a perspective view of sealing portions according to the present invention.

[0054] Referring to FIG. 4, each of the sealing portions 260 and 264 may be made of a polymer resin. Each of the sealing portions 260 and 264 may be made of a thermoplastic polymer resin or a thermosetting polymer resin, specifically a thermoplastic polymer resin. In addition, the polymer resin may be an elastomer.

[0055] The sealing portion 260, which is shown at the upper part of FIG. 4, may be configured as a plug, the radius of the central portion of which is less than the radius of the outer periphery thereof, and the sealing portion 264, which is shown at the lower part of FIG. 4, may be configured such that a projection, the radius of which is gradually increased and is then abruptly decreased, is formed at a portion of the sealing portion configured to be inserted into the cylindrical secondary battery 200.

[0056] FIG. 5 is a view showing an example in which the through-hole according to the present invention is hermetically sealed using a sealing portion. Referring to FIG. 5, the sealing portion 260 may be inserted through the through-hole in order to hermetically seal the through-hole (the figure shown at the upper part of FIG. 5). Alternatively, in a hermetically sealing step, a thermoplastic polymer resin may be injected into the through-hole 250 so as to cover a region at which the negative electrode tab 212 is welded to the cylindrical can 220, whereby a sealing portion 262 may be formed.

[0057] FIG. 6 is a schematic view showing a process of assembling a cylindrical secondary battery according to the present invention.

[0058] In the present invention, a cylindrical secondary battery is assembled as follows.

[0059] A step of forming a through-hole in a bottom portion of a cylindrical secondary battery, a step of receiving an electrode assembly and assembling a cap assembly (1 of FIG. 6), a step of turning the cylindrical secondary battery such that the bottom portion of the cylindrical secondary battery to which with the cap assembly is assembled faces upwards and the cap assembly faces downwards, injecting an electrolytic solution through the through-hole, and activating the cylindrical secondary battery or initially charging and discharging the cylindrical secondary battery (2 of FIG. 6), and a step of hermetically sealing the through-hole using a sealing portion (3 of FIG. 6) are performed, whereby a final cylindrical secondary battery is completed (4 of FIG. 6).

[0060] In addition, the present invention may provide a battery pack including the cylindrical secondary battery.

[0061] Specifically, the battery pack may be used as a power source for a device requiring the ability to withstand high temperature, long cycle characteristics, high rate characteristics, etc. Specific examples of the device may include a mobile electronic device, a wearable electronic device, a power tool driven by a battery-powered motor, an electric automobile, such as an electric vehicle (EV), a hybrid electric vehicle (HEV), or a plug-in hybrid electric vehicle (PHEV), an electric two-wheeled vehicle, such as an electric bicycle (E-bike) or an electric scooter (E-scooter), an electric golf cart, and an energy storage system. However, the present invention is not limited thereto.

[0062] The structure and manufacturing method of the device are well known in the art to which the present invention pertains, and thus a detailed description thereof will be omitted.

[0063] Those skilled in the art to which the present invention pertains will appreciate that various applications and modifications are possible within the category of the present invention based on the above description.

DESCRIPTION OF REFERENCE NUMERALS

[0064] 100, 200: Cylindrical secondary batteries [0065] 110, 210: Electrode assemblies [0066] 111: Positive electrode tab [0067] 112, 212: Negative electrode tabs [0068] 120, 220: Cylindrical cans [0069] 130, 230: Cap assemblies [0070] 131: Top cap [0071] 132: Venting member [0072] 133: Crimping gasket [0073] 134: Lower gasket [0074] 135: Current interrupt member [0075] 250: Through-hole [0076] 260, 262, 264: Sealing portions

INDUSTRIAL APPLICABILITY

[0077] As is apparent from the above description, in the present invention, a bottom portion of a cylindrical secondary battery is provided with a through-hole, which is hermetically sealed using a polymer resin or rubber, and an additional electrolytic solution may be supplied using a syringe even after the through-hole is hermetically sealed.

[0078] In addition, the bottom portion of the secondary battery is concave inwards. Even in the case in which pressure in the secondary battery is high, therefore, the bottom portion of the secondary battery is prevented from being deformed. Since a central portion of the bottom portion is concave, the pressure in the secondary battery is uniformly dispersed, whereby sealability of the secondary battery is excellent.

[0079] In addition, since a sealing portion is added to the central portion of the bottom portion of the cylindrical secondary battery, there is little compatibility problem due to deformation of a case even in the case in which the cylindrical secondary battery is used in a conventional battery module or a conventional battery pack.

[0080] In addition, the bottom portion of the cylindrical secondary battery is perforated, and the sealing portion is added thereto. Perforation is easily and rapidly performed, which is economical.

[0081] In addition, the sealing portion is added in the state in which the thickness thereof is minimized, whereby the capacity of a conventional secondary battery is not reduced.

[0082] In addition, the sealing portion is made of a thermoplastic polymer resin or rubber. In the case in which a portion of the thermoplastic polymer resin or rubber is injected into a can in order to hermetically seal the can, therefore, the thermoplastic polymer resin or rubber wraps a weld region of a negative electrode tab welded to the inner bottom of the can. As a result, it is possible to prevent the weld region in the can from being damaged even in the case in which the cylindrical secondary battery is used for a vehicle, to which strong external impact and vibration are applied.