KR20180017399A - Cap assembly for rechargeable battery - Google Patents

Abstract

The present invention relates to a cap assembly for a secondary battery. According to the present invention, the cap assembly for a secondary battery comprises: a top cap positioned outside a battery in which an electrode assembly is embedded, and including a protruding positive electrode terminal and a plurality of outlets formed around the positive electrode terminal; and a safety belt having a bursting unit capable of discharging inner gas through the outlet by being burst when the inner pressure of the battery is increased. A distance from the bursting unit of the safety belt to the top cap is longer than the length of the bursting unit burst when the inner pressure of the battery is increased.

Description

[0001] CAP ASSEMBLY FOR RECHARGEABLE BATTERY [0002]

The present invention relates to a cap assembly for a secondary battery.

Unlike primary batteries, rechargeable secondary batteries can be recharged, and they are being researched and developed recently due to their small size and high capacity. As technology development and demand for mobile devices increase, the demand for secondary batteries as energy sources is rapidly increasing.

Particularly, the lithium secondary battery has an operating voltage of 3.6 V, which is about three times larger in capacity than a nickel-cadmium battery or a nickel-hydrogen battery widely used as a power source for electronic equipment, and has a high energy density per unit weight. Is rapidly increasing.

Such a lithium secondary battery mainly uses a lithium oxide and a carbonaceous material as a cathode active material and an anode active material, respectively. Further, the lithium secondary battery can be classified into a prismatic battery, a cylindrical battery, and a pouch-type battery.

The lithium ion secondary battery includes an electrode assembly in which an anode / a separator / a cathode are sequentially arranged, and a casing for sealingly storing the electrode assembly together with the electrolyte solution. In particular, the casing of the rectangular or cylindrical secondary battery has a casing having an open end and a cap assembly sealingly coupled to an open end of the casing.

Korean Patent Laid-Open No. 10-2009-0105547

One aspect of the present invention is to provide a cap assembly for a secondary battery capable of smoothly discharging the internal gas to the outside of the battery.

The cap assembly for a secondary battery according to an embodiment of the present invention includes a top cap which is located at an outer periphery of a battery housing an electrode assembly and includes a protruding type of positive terminal and a plurality of outlets formed around the positive terminal, And a safety vent having a rupturing portion ruptured when the internal pressure of the exhaust gas rises to allow discharge of the internal gas to the discharge port,

The straight distance from the rupturing portion to the top cap of the safety vent may be longer than the length of the rupture portion ruptured when the internal pressure of the battery increases.

The cap assembly for a secondary battery according to the present invention is formed in such a structure that the gas can easily be discharged when the internal pressure of the battery rises due to the generation of gas inside the battery. As a result, it is possible to smoothly discharge the gas when a sudden gas is generated inside the battery, thereby reducing the explosive force due to the internal gas, and securing the stability of the battery.

1 is a partial cross-sectional view schematically showing a secondary battery in which a cap assembly for a secondary battery is installed according to an embodiment of the present invention.
2 is a plan view of a top cap in a cap assembly for a secondary battery according to an embodiment of the present invention.
3 is a plan view illustrating a safety vent in a cap assembly for a secondary battery according to an embodiment of the present invention.
4 is a cross-sectional view taken along the line A-A 'in FIG.
5 is a partial cross-sectional view showing an example of a rupture portion of a safety vent ruptured in a cap assembly for a secondary battery according to an embodiment of the present invention.
6 is a partial cross-sectional view showing another example of a rupture portion of a safety vent in a ruptured portion of a safety vent in a cap assembly for a secondary battery according to an embodiment of the present invention.
7 is a plan view showing an example of a current blocking member in a cap assembly for a secondary battery according to an embodiment of the present invention.
8 is a plan view showing another example of a current blocking member in a cap assembly for a secondary battery according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The objectives, specific advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. It should be noted that, in the present specification, the reference numerals are added to the constituent elements of the drawings, and the same constituent elements are assigned the same number as much as possible even if they are displayed on different drawings. Furthermore, the present invention can be embodied in various different forms and is not limited to the embodiments described herein. In the following description of the present invention, a detailed description of related arts which may unnecessarily obscure the gist of the present invention will be omitted.

1 is a partial cross-sectional view schematically showing a secondary battery in which a cap assembly for a secondary battery is installed according to an embodiment of the present invention.

1, a cap assembly 100 for a secondary battery according to an embodiment of the present invention includes a top cap 110 having a cathode terminal 111 and an outlet 112, And a safety vent 130 having a rupturing portion 131 ruptured when the inner pressure of the safety vent 130 rises.

2 is a plan view of a top cap in a cap assembly for a secondary battery according to an embodiment of the present invention.

Hereinafter, a cap assembly for a secondary battery, which is an embodiment of the present invention, will be described in detail with reference to FIGS. 1 to 8. FIG.

1 and 2, the top cap 110 is located at the outer periphery of the secondary battery 10, and may include the positive electrode terminal 111, the discharge port 112, and the receiving portion 113.

Here, the top cap 110 may be located at an outermost position of the battery case 11 in which the electrode assembly 12 is housed. At this time, the top cap 110 may be located at the top of the cylindrical battery case 11, for example.

The positive electrode terminal 111 may protrude from the upper end of the top cap 110 and may form a terminal electrically connected to the electrode assembly 12 accommodated in the secondary battery 10.

The discharge ports 112 are formed around the cathode terminals 111 to discharge gas inside the cells.

The anode terminal 111 may be positioned at the center of the top cap 110 and the outlet 112 may be formed around the cathode terminal 111 in pairs. At this time, the periphery of the discharge port 112 may be formed over 1/2 of the periphery of the anode terminal 111.

The electrode assembly 12 is accommodated in the case 11, and the electrolyte solution can be injected into the case 11. The electrode assembly 12 is a chargeable and dischargeable power generation element, and the electrode 12c and the separation membrane 12d are combined to form a laminated structure. In addition, the electrode may include an anode 12a and a cathode 12b, and the anode 12a may be electrically connected to the cathode terminal 111 of the top cap 110.

The separator 12d separates the anode 12a and the cathode 12b and is made of an insulating material and electrically insulates between the anode 12a and the cathode 12b. At this time, the anode 12a and the cathode 12b may be wound together with the separation membrane 12d and formed into a jelly roll type. Here, the separation membrane 12d may be formed of, for example, a polyolefin-based resin film such as polyethylene or polypropylene having micropores.

The receiving portion 113 may be formed to be opened to the side of the safety vent 130 such that the rupture portion 131 of the safety vent 130 is received in the lower portion of the anode terminal 111. [

The safety element 120 is provided between the top cap 110 and the safety vent 130 to electrically connect the top cap 110 and the safety vent 130. Here, the safety element 120 is for blocking current flow in the battery due to overheating of the battery, and may be formed of, for example, a PTC element (Positive Temperature Coefficient Element).

FIG. 3 is a plan view showing a safety vent in a cap assembly for a secondary battery according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along the line A-A 'in FIG.

1 and 3, the safety vent 130 is positioned inside the secondary battery 10 more than the top cap 110, and the rupture portion 131, the rupture notch 132, and the bending notch 133 .

In addition, the safety vent 130 may open and close the outlet 112 of the top cap 110. Here, the safety vent 130 is positioned on the passage connecting the discharge port 112 of the top cap 110 and the interior of the secondary battery 10. Accordingly, the discharge port 112 of the top cap 110 is closed before the rupture portion 131 of the safety vent 130 is ruptured. When the rupture portion 131 is ruptured due to an increase in internal pressure of the battery, Lt; RTI ID = 0.0 > 112 < / RTI >

The rupturing portion 131 may be positioned in a direction opposite to the anode terminal 111 and the anode terminal 111 and the rupturing portion 131 may be provided in parallel with each other.

In addition, the rupturing portion 131 may rupture toward the top cap 110 when the internal pressure of the battery rises. At this time, a rupture notch 132 may be formed along an edge of the rupturing portion 131. The rupturing portion 131 whose position or shape is changed according to the rupture of the rupture notch 132 ruptures in the direction of the receiving portion 113 of the top cap 110 from the safety vent 130, And can be accommodated in the accommodating portion 113.

In addition, the rupture notch 132 may be formed in the form of a ring having one side open on the plan view.

The bending notch 133 forms a larger circle shape than the rupture notch 132 when viewed in plan view of the safety vent 130. [ That is, the bending notch 133 may be formed at a distance from the rupturing notch 132 along the outer side of the rupturing notch 132 on the top view of the safety vent 130. At this time, the safety vent 130 can be bent toward the top cap 110 around the bending notch 133 when the internal pressure of the battery increases.

4, the rupture notch 132 can form a groove larger than the bending notch 133 so that the rupture notch 132 is first ruptured more than the bending notch 133. [

Here, the width a1 of the rupture notch 132 may be wider than the width a2 of the bending notch 133. The depth b1 of the rupture notch 132 may be deeper than the depth b2 of the bending notch 133. [

FIG. 5 is a partial cross-sectional view showing an example of a state in which the rupture portion 131 of the safety vent is ruptured in the cap assembly for a secondary battery according to an embodiment of the present invention, and FIG. 6 is a cross- Sectional view showing another example in which the rupture portion of the safety vent in the assembly is ruptured. 5 shows a state where the rupturing portion 131 of the safety vent 130 is completely ruptured and Fig. 6 shows a state where the rupturing portion 131 of the safety vent 130 is partially ruptured.

5 and 6, the straight line distance from the rupturing portion 131 to the top cap 110 of the safety vent 130 may be longer than the length of the rupturing portion 131 that ruptures when the internal pressure of the battery increases . That is, the distance A from the rupturing portion 131 to the anode terminal 111 of the top cap 110 may be larger than the diameter B of the rupturing notch 132. Accordingly, it is possible to prevent or minimize the phenomenon that the end portion of the rupturing portion 131 is caught by the positive electrode terminal 111 when the rupturing portion 131 ruptures and the ruptured portion is not opened sufficiently.

Particularly, the distance A from the rupturing portion 131 to the positive electrode terminal 111 of the top cap 110 is smaller than the diameter B of the rupturing notch 132 and the rupture portion 131) of the first and second protrusions (121, 122). This prevents the safety vent 130 from bending toward the top cap 110 and preventing the end of the rupturing portion 131 from being caught by the positive electrode terminal 111 when the rupturing portion 131 is ruptured, Or minimized.

The width C of the positive electrode terminal 111 may be larger than the diameter B of the rupturing notch 132. This prevents or minimizes the phenomenon that the end of the rupturing portion 131 is caught by the side surface of the top cap 110 when the rupturing portion 131 is ruptured and the ruptured portion is not sufficiently opened.

As a result, the cap assembly 100 for a secondary battery according to an embodiment of the present invention as described above sufficiently secures the passage through which the internal gas of the battery is discharged to the discharge port 112 of the top cap 110, . Therefore, it is possible to smoothly discharge the gas when a sudden gas is generated inside the battery.

The current blocking member 140 has one side connected to the safety vent 130 and the other side connected to the electrode assembly 12 and a through hole 141 for discharging the gas. The central portion of the current blocking member 140 protrudes toward the safety vent 130 and is electrically connected to the safety vent 130 as it contacts the rupturing portion 131. When the pressure of the safety vent 130 is applied to the safety vent 130 by the gas that has passed through the through hole 141 of the current blocking member 140 due to the generation of the internal pressure of the battery, The rupturing portion 131 of the safety vent 130 contacting the current blocking member 140 is separated from the current blocking member 140. [ As a result, the contact between the current blocking member 140 and the safety vent 130 is released, and the current connection from the electrode assembly 12 to the cathode terminal 111 is cut off.

FIG. 7 is a plan view showing an example of a current blocking member in a cap assembly for a secondary battery according to an embodiment of the present invention, and FIG. 8 is a view illustrating another example of a current blocking member in a cap assembly for a secondary battery according to an embodiment of the present invention. FIG.

7, the through-holes 141 may be provided on the outer circumferential surface of the current blocking member 140 in a pair. At this time, the through-hole 141 may be formed in an arc shape at a radially symmetric position about the central axis of the current blocking member 140. At this time, the pair of through-holes 141 may be formed over a half of a virtual circumference formed around the center axis of the current blocking member 140. Accordingly, gas can be smoothly discharged through the through-hole 141 when a sudden gas is generated inside the battery.

8, the through-hole 142 may be formed in the form of a ring around the center axis of the current blocking member 140 'on the outer circumferential surface of the current blocking member 140'.

At this time, the ring-shaped through-hole 142 may be formed over a half or more of a virtual circumference formed around the central axis of the current blocking member 140 '. Accordingly, the gas can be smoothly discharged through the through-hole 142 when an abrupt gas is generated in the battery.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the following claims. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Further, the scope of protection of the invention will be clarified by the appended claims.

10: Secondary battery
11: Battery case
12: Electrode assembly
12a: anode
12b: cathode
12c: electrode
12d: Membrane
100: cap assembly
110: Top cap
111: positive terminal
112: Outlet
113:
120: Safety device
130: Safety vent
131:
132: burst notch
133: Bending Notch
140, 140 ': current blocking member
141, 142:

Claims (12)

A top cap which is located at an outer periphery of a cell in which the electrode assembly is embedded and includes a protruding type of positive terminal and a plurality of outlets formed around the positive terminal; And
And a safety vent having a rupturable portion ruptured when the internal pressure of the battery rises to discharge internal gas to the discharge port,
Wherein a straight distance from the rupture portion to the top cap of the safety vent is longer than a length of the rupture portion that ruptures when an internal pressure of the battery increases. The method according to claim 1,
Wherein the safety vent includes a rupture notch formed along an edge of the rupture portion,
Wherein the rupture portion ruptures from the safety vent as the rupture notch ruptures when the internal pressure of the battery rises. The method of claim 2,
Wherein the rupture notch is formed in a circular ring shape on a plane view of the safety vent. The method of claim 3,
Wherein a gap between the rupturing portion and the positive electrode terminal of the top cap is larger than a diameter of the rupture notch. The method of claim 4,
Wherein the safety vent includes a bending notch forming a circle larger than the rupture notch in plan view,
Wherein the safety vent is bent toward the top cap around the bending notch when an internal pressure of the battery increases. The method of claim 5,
Wherein the rupture notch forms a groove larger than the bending notch so that the rupture notch ruptures earlier than the bending notch. The method according to any one of claims 3 to 6,
Wherein a width of the positive electrode terminal is larger than a diameter of the rupture notch. The method of claim 7,
Wherein the cathode terminal is located at a central portion of the top cap, the outlet is formed in a pair around the cathode terminal,
The periphery of the pair of the discharge ports is formed over 1/2 of the periphery of the cathode terminal,
Wherein the rupture portion of the safety vent is disposed in a direction opposite to the positive electrode terminal and is disposed in parallel to each other. The method of claim 5,
Further comprising a current blocking member having one side connected to the safety vent and the other side connected to the electrode assembly and having a through hole for discharging the gas,
Wherein the safety vent is bent in the direction of the current blocking member around the bending notch and is bent in the direction of the top cap around the bending notch when the internal pressure of the battery increases. The method of claim 9,
The gap from the rupturing portion to the positive electrode terminal of the top cap
Wherein the diameter of the rupture notch is greater than the sum of the diameter of the rupture notch and the distance of movement of the rupture part when the safety vent is bent. The method of claim 9,
Wherein the through-holes are provided in pairs on an outer circumferential surface of the current blocking member,
Wherein the cap assembly is formed in an arc shape at a radially symmetric position about a central axis. The method of claim 9,
Wherein the through-hole is formed in the shape of a ring around the central axis on the outer circumferential surface of the current blocking member.

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