Secondary battery comprising insulator assembly capable of suppressing damage to electrode assembly caused by external force

1. A secondary battery comprising:

a container;

an electrode assembly that is disposed in the container and includes a cathode, an anode, and

a separating membrane disposed between the cathode and the anode; and

an insulator assembly that is mounted on an upper end of the electrode assembly, a lower end thereof, or both,

wherein the insulator assembly includes: (i) a first insulating plate formed of a woven structure of polymer fibers, (ii) a second insulating plate formed of a nonwoven structure of polymer fibers, (iii) a third insulating plate formed of a nonwoven or woven structure of polymer fibers and provided with a plurality of apertures, or (iv) a combination thereof, and

wherein, when the electrode assembly is moved upwardly or downwardly due to inertia, the insulator assembly is elastically contracted and restored as a reaction to the inertia to reduce pressure generated between the electrode assembly and an interior surface of the container.

2. The secondary battery according to claim 1 , wherein the electrode assembly forms a jelly-roll of the cathode formed in a sheet shape, the separating membrane formed in a sheet shape, and the anode formed in a sheet shape that are stacked and wound in a direction from an end of the jelly-roll to the other end thereof.

3. The secondary battery according to claim 1 , wherein the insulator assembly includes a first insulator coupled to the upper end of the electrode assembly and a second insulator coupled to the lower end of the electrode assembly.

4. The secondary battery according to claim 3 , wherein the first insulator comprises:

a stacked body in which two, three or four of the third insulating plates formed of a nonwoven structure of polymer fibers are stacked vertically;

a first insulating plate stacked on the stacked body; and

another first insulating plate stacked under the stacked body, wherein the thickness of the first insulator is about 1 mm to about 2 mm.

5. The secondary battery according to claim 3 , the second insulator comprises:

a stacked body in which a plurality of the second insulating plates formed of a nonwoven structure of polymer fibers are stacked vertically;

a first insulating plate stacked on the stacked body; and

another first insulating plate stacked under the stacked body.

6. The secondary battery according to claim 3 , wherein the first insulator comprises:

a stacked body in which a plurality of the third insulating plates formed of a nonwoven structure of polymer fibers are stacked vertically;

a first insulating plate stacked on the stacked body; and

another first insulating plate stacked under the stacked body.

7. The secondary battery according to claim 6 , wherein each of the third insulating plates is about 0.2 mm to about 0.5 mm in thickness, and each of the first insulating plates is about 0.1 mm to about 0.3 mm in thickness.

8. The secondary battery according to claim 6 , wherein nonwoven polymer fibers of each of the third insulating plates are intertwined with each other to form a space around the intertwined nonwoven polymer fibers,

wherein the first insulating plate is bonded by thermal fusion to a third insulating plate adjacent to the first insulation plate, and

wherein the another first insulating plate is bonded by thermal fusion to a third insulating plate adjacent to the another first insulation plate.

9. The secondary battery according to claim 8 , wherein when the electrode assembly is moved upwardly, the space becomes smaller or is removed, and the third insulating plates becomes closer to each other, thereby causing the first insulator to be contracted along a vertical section thereof so that the contraction of the first insulator can reduce upward movement of the electrode assembly and absorb some or all of pressure applied to the upper end of the electrode assembly.

10. The secondary battery according to claim 6 , wherein the third insulating plates are stacked so that the apertures of each of the third insulating plates are in communication with each other.

11. The secondary battery according to claim 10 , wherein each of the second insulating plates is about 0.2 mm to about 0.5 mm in thickness, and each of the first insulating plates is about 0.1 mm to about 0.3 mm in thickness.

12. The secondary battery according to claim 10 , wherein the second insulator comprises:

a stacked body in which five to ten of the second insulating plates formed of a nonwoven structure of polymer fibers are stacked vertically;

a first insulating plate stacked on the stacked body; and

another first insulating plate stacked under the stacked body,

wherein the thickness of the second insulator is about 2 mm to about 5 mm.

13. The secondary battery according to claim 10 , wherein nonwoven polymer fibers of each of the second insulating plates are intertwined with each other to form a space around the intertwined nonwoven polymer fibers,

wherein the first insulating plate is bonded by thermal fusion to a second insulating plate adjacent to the first insulation plate, and

wherein the another first insulating plate is bonded by thermal fusion to a second insulating plate adjacent to the another first insulation plate.

14. The secondary battery according to claim 13 , wherein when the electrode assembly is moved downwardly, the space becomes smaller or is removed, and the second insulating plates becomes closer to each other, thereby causing the second insulator to be contracted along a vertical section thereof so that the contraction of the second insulator can reduce downward movement of the electrode assembly and absorb some or all of pressure applied to the lower end of the electrode assembly.