Non-aqueous electrolyte secondary battery

Abstract

A non-aqueous electrolyte secondary battery including a unit cell including a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte, the positive electrode capacity being greater than the negative electrode capacity, and at least a portion of the non-aqueous electrolyte is gasified during charging.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a graph showing charge and discharge behavior of a non-aqueous electrolyte secondary battery of the present invention.

FIG. 2 is a graph showing discharge performance under high load of a non-aqueous electrolyte secondary battery of the present invention.

FIG. 3 is a graph showing charge and discharge behavior under positive electrode capacity regulation.

FIG. 4 is another graph showing charge and discharge behavior under positive electrode capacity regulation.

FIG. 5 is still another graph showing charge and discharge behavior of positive electrode capacity regulation.

FIG. 6 is a graph showing charge and discharge behavior in Comparative Example using EC/DMC type electrolyte.

FIG. 7 is a graph showing the results of impedance measurement in the present invention using AN type electrolyte.

FIG. 8 is a graph showing the results of impedance measurement by using EC/DMC type electrolyte.

FIG. 9 is a graph showing charge and discharge behavior of the present invention using AN/GBL type electrolyte.

FIG. 10 is a graph showing cycle life of the present invention using AN/GBL type electrolyte.

FIG. 11 is a schematic vertical cross section of a unit cell (non-aqueous electrolyte secondary battery, a cell for electrochemical test) made in Examples of the present invention.

FIG. 12 is a schematic perspective view of a battery module comprising a group of unit cells in which five unit cells 20 of FIG. 11 are connected in series.

Claims

1. A non-aqueous electrolyte secondary battery comprising a unit cell including a positive electrode, a negative electrode, a separator disposed between said positive electrode and said negative electrode, and a non-aqueous electrolyte, wherein a positive electrode capacity is greater than a negative electrode capacity, and at least a portion of the non-aqueous electrolyte is gasified.

2. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein said unit cell comprises a plurality of unit cells, and capacity variation between said unit cells is compensated.

3. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein said at least a portion of the non-aqueous electrolyte is gasified in the proximity of said negative electrode.

4. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein said at least a portion of the non-aqueous electrolyte is gasified in the range of 1.5 V to 0.3 V relative to a lithium metal.

5. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein a metal electrode for gasification is included.

6. The non-aqueous electrolyte secondary battery in accordance with claim 5, wherein said metal electrode includes at least one selected from the group consisting of nickel, copper, iron, and stainless.

7. The non-aqueous electrolyte secondary battery in accordance with any of claim 1, wherein said negative electrode includes a lithium-containing titanium oxide as a negative electrode material.

8. The non-aqueous electrolyte secondary battery in accordance with claim 7, wherein said lithium-containing titanium oxide is Li3+3xTi6−3xO12 where 0≦x≦⅓.

9. The non-aqueous electrolyte secondary battery in accordance with claim 8, wherein said lithium-containing titanium oxide comprises a mixture of crystal particles having a particle size of 0.1 μm to 8 μm and secondary particles of the crystal particles, said secondary particles having a particle size of 2 μm to 30 μm.

10. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein said negative electrode comprises a current collector including aluminum or an aluminum alloy.

11. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein said non-aqueous electrolyte contains a nitrile compound as a solvent.

12. The non-aqueous electrolyte secondary battery in accordance with claim 11, wherein said nitrile compound is a mononitrile compound.

13. The non-aqueous electrolyte secondary battery in accordance with claim 12, wherein said mononitrile compound is acetonitrile or propionitrile.

14. The non-aqueous electrolyte secondary battery in accordance with claim 11, wherein said nitrile compound further includes a dinitrile compound.

15. The non-aqueous electrolyte secondary battery in accordance with claim 14, wherein said dinitrile compound is malononitrile, succinonitrile, glutaronitrile, or adiponitrile.

16. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein said non-aqueous electrolyte contains methyl acetate, methyl butyrate, or γ-butyrolactone as a solvent.

17. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein said positive electrode includes a spinel lithium-containing manganese composite oxide as a positive electrode active material.

18. The non-aqueous electrolyte secondary battery in accordance with claim 17, wherein said spinel lithium-containing manganese composite oxide is Li1+xMn2−x−6yAyO4 where A is at least one selected from the group consisting of Al, Ni, and Fe, 0≦x≦⅓, and 0≦y≦0.6.

19. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein said positive electrode includes a layer-structured Li1+α[Me]O2 where Me is a transition metal including Ni and at least one selected from the group consisting of Mn, Fe, Co, Ti, and Cu, and 0≦α≦0.2, as a positive electrode active material.

20. The non-aqueous electrolyte secondary battery in accordance with claim 19, wherein said positive electrode active material is Li1+α[Ni1/2-zMn1/2-zCo2z]O2 where 0≦α≦0.2, and z≦⅙.

21. A non-aqueous electrolyte secondary battery comprising a unit cell including a positive electrode, a negative electrode, a separator disposed between said positive electrode and said negative electrode, and a non-aqueous electrolyte, wherein said positive electrode includes a positive electrode active material comprising a spinel lithium composite oxide represented by the general formula: Li+xM2−xO4

22. A non-aqueous electrolyte secondary battery comprising a unit cell including a positive electrode, a negative electrode, a separator disposed between said positive electrode and said negative electrode, and a non-aqueous electrolyte, wherein said positive electrode includes a positive electrode active material comprising a spinel lithium composite oxide represented by the general formula: Li1+xMn2−x−yAyO4