Lithium secondary battery

Abstract

A lithium secondary battery includes: a plurality of sheets of a positive electrode; at least one sheet of a negative electrode; a separator disposed between each of the positive electrode sheets and the negative electrode sheet; an electrode assembly (20) including the positive electrode, the negative electrode, and the separators; a battery case for accommodating the electrode assembly; and positive electrode current collector tabs (1), attached to individual sheets of the positive electrode, for connecting the sheets of the positive electrode to a positive electrode terminal portion of the battery case. The electrode assembly (20) is formed so that the plurality of sheets of positive electrode and the at least one sheet of the negative electrode are stacked with the separators interposed therebetween. In the electrode assembly in which the electrodes are stacked, the positive electrode current collector tabs are disposed staggered at a plurality of locations.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cut-away perspective view illustrating one example of the lithium secondary battery according to the present invention;

FIG. 2 is a partially cut-away perspective view illustrating a conventional lithium secondary battery;

FIG. 3 is a plan view illustrating an electrode assembly used in the example of the lithium secondary battery of the present invention;

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a cross-sectional view illustrating the structure of the electrode assembly in another example of the lithium secondary battery according to the present invention;

FIG. 6(A) is a perspective view illustrating an electrode assembly of the present invention and showing the positive electrode current collector tabs staggered at five locations;

FIG. 6(B) is a perspective view illustrating the electrode assembly of FIG. 6(A) inserted in a battery can; and

FIG. 7 is a perspective view of the electrode assembly of Japanese Published Unexamined Patent Application No. 2005-174653.

Claims

1. A lithium secondary battery comprising: a plurality of sheets of a positive electrode;at least one sheet of a negative electrode;a separator disposed between each positive electrode sheet and the at least one sheet of negative electrode;an electrode assembly comprising the plurality of sheets of the positive electrode, the at least one sheet of the negative electrode, and the separator, in which the plurality of sheets of positive electrode and the at least one sheet of the negative electrode are stacked with the separators interposed therebetween;a battery case for accommodating the electrode assembly; andpositive electrode current collector tabs, attached to individual sheets of the positive electrode, for connecting the sheets of the positive electrode to a positive electrode terminal portion of the battery case, the positive electrode current collector tabs being disposed staggered at a plurality of locations in the electrode assembly in which the electrodes are stacked.

2. The lithium secondary battery according to claim 1, wherein, in the electrode assembly in which the electrodes are stacked, positive electrode current collector tabs are overlapped and the number that are overlapped at a same location is three or less.

3. The lithium secondary battery according to claim 1, wherein, in the electrode assembly in which the electrodes are stacked, the at least one sheet of the negative electrode is folded and overlapped alternately and the sheets of the positive electrode are disposed between overlapping surfaces of the negative electrode, whereby the positive electrode and the negative electrode are stacked.

4. The lithium secondary battery according to claim 2, wherein, in the electrode assembly in which the electrodes are stacked, the at least one sheet of the negative electrode is folded and overlapped alternately and the sheets of the positive electrode are disposed between overlapping surfaces of the negative electrode, whereby the positive electrode and the negative electrode are stacked.

5. The lithium secondary battery according to claim 1, wherein, in the electrode assembly in which the electrodes are stacked, the positive electrode is not disposed on an outer side of a folded portion of the negative electrode.

6. The lithium secondary battery according to claim 2, wherein, in the electrode assembly in which the electrodes are stacked, the positive electrode is not present on an outer side of a folded portion of the negative electrode.

7. The lithium secondary battery according to claim 3, wherein, in the electrode assembly in which the electrodes are stacked, the positive electrode is not present on an outer side of a folded portion of the negative electrode.

8. The lithium secondary battery according to claim 4, wherein, in the electrode assembly in which the electrodes are stacked, the positive electrode is not present on an outer side of a folded portion of the negative electrode.

9. The lithium secondary battery according to claim 1, wherein the negative electrode contains silicon as an active material.

10. The lithium secondary battery according to claim 2, wherein the negative electrode contains silicon as an active material.

11. The lithium secondary battery according to claim 7, wherein the negative electrode contains silicon as an active material.

12. The lithium secondary battery according to claim 8, wherein the negative electrode contains silicon as an active material.

13. The lithium secondary battery according to claim 9, wherein the negative electrode comprises a negative electrode current collector and a negative electrode mixture layer sintered on the negative electrode current collector, the negative electrode mixture layer containing a negative electrode binder and an active material containing silicon.

14. The lithium secondary battery according to claim 12, wherein the negative electrode comprises a negative electrode current collector and a negative electrode mixture layer sintered on the negative electrode current collector, the negative electrode mixture layer containing a negative electrode binder and an active material containing silicon.

15. The lithium secondary battery according to claim 13, wherein the negative electrode binder comprises a polyimide.

16. The lithium secondary battery according to claim 14, wherein the negative electrode binder comprises a polyimide.

17. The lithium secondary battery according to claim 1, wherein the battery case is formed of aluminum, an aluminum alloy or an aluminum laminate film.

18. The lithium secondary battery according to claim 4, wherein the battery case is formed of aluminum, an aluminum alloy or an aluminum laminate film.

19. The lithium secondary battery according to claim 12, wherein the battery case is formed of aluminum, an aluminum alloy or an aluminum laminate film.

20. The lithium secondary battery according to claim 16, wherein the battery case is formed of aluminum, an aluminum alloy or an aluminum laminate film.