Battery cell having double sealing structure

Abstract

Disclosed is a battery cell having a double sealing structure. In particular, the battery cell includes a first sealing portion formed at an outer circumferential surface of a battery case by thermal bonding and a second sealing portion further formed between an electrode assembly and the first sealing portion at at least one side surface of the first sealing portion.

Claims

1. A battery cell in which an electrode assembly with a first electrolyte therein is accommodated in a state of being connected to electrode terminals protruding from a battery case, the battery cell comprising a first sealing portion formed at an outer circumferential surface of the battery case by thermal bonding and a second sealing portion further formed between the electrode assembly and the first sealing portion at at least one side surface of the first sealing portion, wherein a space is formed between the first sealing portion and the second sealing portion and opposite to the electrode assembly, wherein the electrode assembly is not accommodated in said space, wherein the space has a volume of 5% to 50% based on a total volume of an inside of the battery cell, wherein second electrolyte is included in the space for being introduced into the battery cell via the second sealing portion when the second sealing portion is damaged by gas generated, and wherein the second sealing portion has a lower sealing strength than the first sealing portion.

2. The battery cell according to claim 1, wherein the second sealing portion is formed at a surface at which the electrode terminals are not positioned.

3. The battery cell according to claim 1, wherein the second sealing portion is formed at a surface to which greatest internal pressure is applied.

4. The battery cell according to claim 1, wherein the second electrolyte is included in an amount of 5% to 50% based on a total volume of the space.

5. The battery cell according to claim 1, wherein the second sealing portion has a sealing strength of 1.0 kg/cm.sup.2 to 1.9 kg/cm.sup.2.

6. The battery cell according to claim 1, wherein the first sealing portion has a sealing strength of 2.0 kg/cm.sup.2 to 4.5 kg/cm.sup.2.

7. The battery cell according to claim 1, wherein the second sealing portion has a lower area than the first sealing portion.

8. The battery cell according to claim 1, wherein the electrode assembly comprises a cathode, an anode, and a separator disposed between the cathode and the anode.

9. The battery cell according to claim 8, wherein the cathode comprises a lithium transition metal oxide represented by Formula 1 or 2 below as a cathode active material:
Li.sub.xM.sub.yMn.sub.2-yO.sub.4-zA.sub.z  (1) wherein M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, Ti, and Bi; A is at least one monovalent or divalent anion; and
0.9≦x≦1.2, 0<y<2, and 0≦z<0.2,
(1−x)LiM′O.sub.2-yA.sub.y-xLi.sub.2MnO.sub.3-y′A.sub.y′  (2) wherein M′ is Mn.sub.aM.sub.b; M is at least one selected from the group consisting of Ni, Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn, and Period 2 transition metals; A is at least one selected from the group consisting of PO.sub.4, BO.sub.3, CO.sub.3, F and NO.sub.3 anions; and
0<x<1, 0<y≦0.02, 0<y′≦0.02, 0.5≦a≦1.0, 0≦b≦0.5, and a+b=1.

10. The battery cell according to claim 8, wherein the anode comprises a carbon-based material and/or Si as an anode active material.

11. The battery cell according to claim 1, wherein the battery cell is a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery.

12. A battery module comprising the battery cell according to claim 1 as a unit cell.

13. A battery pack comprising the battery module according to claim 12.

14. A device comprising the battery pack according to claim 13 as a power source.

15. The device according to claim 14, wherein the device is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a system for storing power.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawing, in which:

(2) FIG. 1 is a view of a battery cell A including first and second sealing portions according to an embodiment of the present invention; and

(3) FIG. 2 is a view of a battery cell B including first and second sealing portions according to another embodiment of the present invention.

BEST MODE

(4) Now, the present invention will be described in more detail with reference to the following examples. These examples are provided only for illustration of the present invention and should not be construed as limiting the scope and spirit of the present invention.

(5) FIG. 1 is a view of a battery cell A 100 including first and second sealing portions according to an embodiment of the present invention.

(6) Referring to FIG. 1, an electrode assembly 160 is accommodated in the battery cell A 100 of a pouch type in a state of being connected to electrode terminals 110 and 112 protruding from a battery case 170, a first sealing portion 140 is formed at an outer circumferential surface of the battery case 170 by thermal bonding, and a second sealing portion 150 is further formed between the electrode assembly 160 and the first sealing portion 140 at at least one side surface of the first sealing portion 140.

(7) The second sealing portion 150 is formed at a surface at which the electrode terminals 110 and 112 are not positioned, and a space 180 is formed between the first sealing portion 140 and the second sealing portion 150. The space 180 includes extra electrolyte to prevent reduction in lifespan of the battery cell A 100 due to loss of an electrolyte or is formed as an empty space so as to induce gas leaked via a damaged portion of the second sealing portion 150 to move to the space 180 so that leakage of gas from the battery cell A 100 is prevented.

(8) Thus, the second sealing portion 150 has a lower sealing strength than the first sealing portion 140.

(9) FIG. 2 is a view of a battery cell B 200 including first and second sealing portions 240 and 250 according to another embodiment of the present invention.

(10) Referring to FIG. 2, the second sealing portion 250 is formed at a lower portion of the battery cell B 200 to which great internal pressure is applied. A space 280 is formed between the first and second sealing portions 240 and 250. Similar to the space 180, the space 280 includes extra electrolyte to prevent reduction in lifespan of the battery cell B 200 due to loss of electrolyte or is formed as an empty space so as to induce gas leaked via a damaged portion of the second sealing portion 250 to move to the space 280 so that leakage of gas from the battery cell B 200 is prevented.

(11) Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.