Cylindrical lithium ion secondary battery

Abstract

In a cylindrical lithium ion secondary battery, the width of an electrode tab positioned at a center of an electrode assembly is extended so that it serves as a center pin and functions to release heat. Thus, it is not necessary to separately insert a center pin, thereby reducing the manufacturing cost and steps. The cylindrical lithium ion secondary battery comprises an electrode assembly, a case for receiving the electrode assembly, and a cap assembly for sealing the top opening of the case. The electrode assembly comprises a positive electrode plate and negative electrode plate. The positive electrode plate has a positive electrode tab, a positive active material region, a positive uncoated region, and a positive current collector exposed through the positive uncoated region. The negative electrode plate has a negative electrode tab, a negative active material region, a negative uncoated region, a negative current collector exposed through the negative uncoated region, and a separator interposed between the positive and negative electrode plates. At least one of the positive and negative electrode tabs has an extended width at the center of the electrode assembly.

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 cross-sectional view of a cylindrical lithium ion secondary battery with a cylindrical center pin which is separately inserted;

FIG. 2 is a top plan view of an inventive electrode assembly which, according to the present invention, is formed with electrode tabs prior to winding the electrode assembly;

FIG. 3 is a top plan view of the inventive electrode assembly which, according to the present invention, is formed with electrode tabs after winding the electrode assembly;

FIG. 4 is a perspective view showing the shape of an electrode having an electrode tab, the width of which extends toward a winding core of an electrode assembly, according to an embodiment of the present invention;

FIG. 5 is a perspective view showing the shape of an electrode having an electrode tab, the width of which extends away from the winding core of an electrode assembly, according to another embodiment of the present invention;

FIG. 6 is a top plan view of an electrode tab according to another embodiment of the present invention;

FIG. 7 is a perspective view showing the shape of an electrode plate according to another embodiment of the present invention; and

FIGS. 8 a, 8b and 8c are perspective views showing the shapes of electrode plates of other embodiments of the present invention.

Claims

1. A cylindrical lithium ion secondary battery, comprising: an electrode assembly including a positive electrode plate having a positive electrode tab, a positive active material region, a positive uncoated region formed adjacent to the positive active material region, a positive current collector exposed through the positive uncoated region, a negative electrode plate having a negative electrode tab, a negative active material region, a negative uncoated region formed adjacent to the negative active material region, a negative current collector exposed through the negative uncoated region, and a separator interposed between the positive electrode plate and the negative electrode plate;a case for receiving the electrode assembly; anda cap assembly for sealing a top opening of the case;wherein at least one of the positive electrode tab and the negative electrode tab is formed so as to have an extended width at a center of the electrode assembly.

2. The cylindrical lithium ion secondary battery as claimed in claim 1, wherein said at least one of the positive electrode tab and the negative electrode tab has a width extending toward a winding core of the electrode assembly.

3. The cylindrical lithium ion secondary battery as claimed in claim 2, wherein said at least one of the positive electrode tab and the negative electrode tab has a projection portion which is higher than another portion of said at least one of the positive electrode tab and the negative electrode tab and which is exposed above the electrode assembly, and a center pin portion which is connected to the projection portion and which has a width extending toward the winding core of the electrode assembly.

4. The cylindrical lithium ion secondary battery as claimed in claim 3, wherein a height of the center pin portion is equal to a height of the electrode assembly.

5. The cylindrical lithium ion secondary battery as claimed in claim 3, wherein the center pin portion is wound in a circular arc form in cross-section, and a length of the circular arc is not less than 70% of a circumference of an entire circle including the circular arc.

6. The cylindrical lithium ion secondary battery as claimed in claim 3, wherein the center pin portion is welded to a corresponding electrode plate over its entire area.

7. The cylindrical lithium ion secondary battery as claimed in claim 6, wherein a welded area of the center pin portion is an uncoated region in the corresponding electrode plate.

8. The cylindrical lithium ion secondary battery as claimed in claim 3, wherein the center pin portion comprises a first area defined by vertical extension lines of opposite sides of the projection portion, and a second area which is a remaining area exclusive of the first area of the center pin portion.

9. The cylindrical lithium ion secondary battery as claimed in claim 1, wherein said at least one of the positive electrode tab and the negative electrode tab has a width extending away from a winding core of the electrode assembly.

10. The cylindrical lithium ion secondary battery as claimed in claim 9, wherein said at least one of the positive electrode tab and the negative electrode tab has a projection portion which is higher than another portion of said at least one of the positive electrode tab and the negative electrode tab and which is exposed above the electrode assembly, and a center pin portion which is connected to the projection portion and which has a width extending away from the winding core of the electrode assembly.

11. The cylindrical lithium ion secondary battery as claimed in claim 10, wherein a height of the center pin portion is equal to a height of the electrode assembly.

12. The cylindrical lithium ion secondary battery as claimed in claim 10, wherein the center pin portion is wound in a circular arc form in cross-section, and a length of the circular arc is not less than 70% of a circumference of an entire circle including the circular arc.

13. The cylindrical lithium ion secondary battery as claimed in claim 10, wherein the center pin portion is welded to a corresponding electrode plate over its entire area.

14. The cylindrical lithium ion secondary battery as claimed in claim 13, wherein a welded area of the center pin portion is an uncoated region in the corresponding electrode plate.

15. The cylindrical lithium ion secondary battery as claimed in claim 9, wherein the center pin portion comprises a first area defined by vertical extension lines of opposite sides of the projection portion, and a second area which is a remaining area exclusive of the first area of the center pin portion.

16. The cylindrical lithium ion secondary battery as claimed in claim 15, wherein the center pin portion is welded to the corresponding electrode plate only at the first area.

17. The cylindrical lithium ion secondary battery as claimed in claim 16, wherein the center pin portion has a plurality of holes formed in the second area.

18. The cylindrical lithium ion secondary battery as claimed in claim 17, wherein the holes are formed in any shape selected from a group consisting of circular, triangular and rectangular shapes.

19. The cylindrical lithium ion secondary battery as claimed in claim 15, wherein the corresponding electrode plate has an uncoated region formed at an area where the corresponding electrode plate contacts the first area, and an electrode active material region formed at an area where the corresponding electrode plate contacts the second area.

20. The cylindrical lithium ion secondary battery as claimed in claim 1, wherein the electrode tab is formed of one of aluminum (Al) and nickel (Ni).