Separator, a lithium rechargeable battery using the same and a method of manufacture thereof

Abstract

A separator, a lithium rechargeable battery using the separator, and a method of manufacturing the lithium rechargeable battery. More particulary, a separator in which a plurality of porous films having different strength from one another are disposed between a positive electrode plate and a negative electrode plate. A porous film having a higher tensile strength is disposed at a region adjacent to the negative electrode plate, and the other porous film is disposed adjacent the positive electrode plate. The porous film having the higher tensile strength has smaller holes and/or is thicker than the other porous film. The separator improves the stability of the battery by improving the prevention of an electrical short occurring between the two electrode plates of the electrode assembly, and a lithium rechargeable battery using the same.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:

FIG. 1 is a vertical cross-sectional view of a typical lithium rechargeable battery;

FIG. 2A is a vertical cross-sectional view of a lithium rechargeable battery according to an embodiment of the present invention;

FIG. 2B is a perspective view of an electrode assembly according to an embodiment of the present invention;

FIG. 2C is a horizontal cross-sectional view of the electrode assembly of FIG. 2B prior to be wound;

FIG. 3 is a horizontal cross-sectional view of an electrode assembly prior to be wound, according to another embodiment of the present invention; and

FIG. 4 is a horizontal cross-sectional view of an electrode assembly prior to be wound, according to anther embodiment of the present invention.

Claims

1. A separator for a lithium rechargeable battery which is disposed between a positive electrode plate and a negative electrode plate, said separator having at least two overlapping porous films each having a different pore size, and having a space between the porous films to be filled with an electrolyte.

2. The separator according to claim 1, wherein said at least two overlapping porous films comprise a porous film adjacent to the negative electrode plate has a smaller pore size than a porous film adjacent to the positive electrode plate.

3. The separator according to claim 1, wherein said at least two overlapping porous films comprise a first porous film having a first pore size and a second porous film having a bigger pore size than the pore size of the first porous film.

4. The separator according to claim 1, wherein, in the separator, the porous film adjacent to the negative electrode plate and the porous film adjacent to the positive electrode plate have different tensile strength from each other.

5. The separator according to claim 2, wherein, in the separator, the porous film adjacent to the negative electrode plate and the porous film adjacent to the positive electrode plate have different tensile strength from each other.

6. The separator according to claim 5, wherein, in the separator, the porous film adjacent to the negative electrode plate has a greater tensile strength than the porous film adjacent to the positive electrode plate.

7. The separator according to claim 1, wherein, in the separator, the porous film adjacent to the negative electrode plate and the porous film adjacent to the positive electrode plate have a different film thickness from each other.

8. The separator according to claim 2, wherein, in the separator, the porous film adjacent to the negative electrode plate and the porous film adjacent to the positive electrode plate have a different film thickness from each other.

9. The separator according to claim 7, wherein, in the separator, the porous film adjacent to the negative electrode plate has a greater thickness than the porous film adjacent to the positive electrode plate.

10. A lithium rechargeable battery comprising: an electrode assembly having a positive electrode plate, a negative electrode plate facing the positive electrode plate, and a separator disposed between the positive electrode plate and the negative electrode plate;a can which contains the electrode assembly; anda cap assembly which seals an upper opening portion of the can,wherein the separator is constructed by overlapping at least two porous films having a different pore size, and a space exists between the porous films to be filled with an electrolyte.

11. The lithium rechargeable battery according to claim 10, wherein a porous film adjacent to the negative electrode plate has a smaller pore size than a porous film adjacent to the positive electrode plate.

12. The separator according to claim 10, wherein, in the separator, the porous film adjacent to the negative electrode plate and the porous film adjacent to the positive electrode plate have a different tensile strength from each other.

13. The separator according to claim 11 wherein, in the separator, the porous film adjacent to the negative electrode plate and the porous film adjacent to the positive electrode plate have a different tensile strength from each other.

14. The separator according to claim 12, wherein, in the separator, the porous film adjacent to the negative electrode plate has a greater tensile strength than the porous film adjacent to the positive electrode plate.

15. The separator according to claim 10, wherein, in the separator, the porous film adjacent to the negative electrode plate and the porous film adjacent to the positive electrode plate have different film thickness from each other.

16. The separator according to claim 11, wherein, in the separator, the porous film adjacent to the negative electrode plate and the porous film adjacent to the positive electrode plate have different film thickness from each other.

17. The separator according to claim 15, wherein, in the separator, the porous film adjacent to the negative electrode plate has a greater thickness than the porous film adjacent to the positive electrode plate.

18. A lithium rechargeable battery comprising: a positive electrode plate and a negative electrode plate; anda separator disposed between the positive electrode plate and the negative electrode plate, said separator having at least two overlapping porous films each having a different tensile strength from one another.

19. The separator according to claim 18, one of said porous films being disposed adjacent to the negative electrode plate and having a greater thickness and higher tensile strength than another of said porous films being disposed adjacent to the positive electrode plate.

20. The separator according to claim 18, one of said porous films being disposed adjacent to the negative electrode plate and having a smaller pore size than another of said porous films being disposed adjacent to the positive electrode plate.

21. The separator according to claim 18, said overlapping porous films being separated by a space in which an electrolyte is disposed.

22. A method of manufacturing lithium rechargeable batteries, the method comprising: disposing a first porous film having a first pore size and a second porous film having a second pore size bigger than the first pore size, between a positive electrode plate and a negative electrode plate;winding the positive electrode plate, the first porous film, the second porous film and the negative electrode plate to form a winding;inserting the winding into a can; andclosing the can with a cap assembly.