Non-aqueous electrolyte secondary battery

1. A non-aqueous electrolyte secondary battery comprising a unit cell including a sheet-shaped positive electrode, a sheet-shaped negative electrode, a separator disposed between said positive electrode and said negative electrode, and a non-aqueous electrolyte, wherein:

said non-aqueous electrolyte contains a solvent including 50 vol % or more of acetonitrile,

said positive electrode includes a positive electrode active material and a positive current collector including aluminum or an aluminum alloy, said positive current collector contacting said non-aqueous electrolyte on both sides of said positive electrode,

said positive electrode includes a positive electrode active material comprising a lithium-containing manganese composite oxide having a spinel structure,

said negative electrode includes a negative electrode active material comprising a lithium-containing titanium oxide and a negative current collector including aluminum or an aluminum alloy, said negative current collector contacting said non-aqueous electrolyte on both sides of said negative electrode;

a positive electrode capacity is greater than a negative electrode capacity, and at least a portion of said acetonitrile is capable of being gasified during the overcharging of said battery;

said unit cell further includes a third metal electrode; and

said third metal electrode includes at least one selected from the group consisting of nickel, copper, iron, and stainless steel.

2. The non-aqueous electrolyte secondary battery in accordance with claim 1 , comprising a plurality of said unit cells, and being capable of compensating capacity variation between said unit cells.

3. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said at least a portion of said acetonitrile is capable of being 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 said acetonitrile is capable of being gasified in the negative electrode potential 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 said lithium-containing titanium oxide is Li 3+3x Ti 6−3x O 12 where 0≦x≦⅓.

6. The non-aqueous electrolyte secondary battery in accordance with claim 5 , 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.

7. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said non-aqueous electrolyte further includes a dinitrile compound.

8. The non-aqueous electrolyte secondary battery in accordance with claim 7 , wherein said dinitrile compound is malononitrile, succinonitrile, glutaronitrile, or adiponitrile.

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

10. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said spinel lithium-containing manganese composite oxide is Li 1+x Mn 2−x−y A y O 4 where A is at least one selected from the group consisting of Al, Ni, and Fe, 0≦x≦⅓, and 0≦y≦0.6.

11. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said positive electrode includes a layer-structured Li 1+α [Me]O 2 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 said positive electrode active material.

12. The non-aqueous electrolyte secondary battery in accordance with claim 11 , wherein said positive electrode active material is Li 1+α [Ni 1/2−z Mn 1/2−z Co 2z ]O 2 where 0≦α≦0.2, and z≦⅙.

13. A non-aqueous electrolyte secondary battery comprising a unit cell including a sheet-shaped positive electrode, a sheet-shaped negative electrode, a separator disposed between said positive electrode and said negative electrode, and a non-aqueous electrolyte, a positive electrode capacity being greater than a negative electrode capacity,

wherein said positive electrode includes a positive electrode active material comprising a spinel lithium composite oxide represented by the general formula:

Li 1+x M 2−X O 4

where M is at least Mn and Al, and x>0, and a positive current collector including aluminum or an aluminum alloy, said positive current collector contacting said non-aqueous electrolyte on both sides of said positive electrode;

said negative electrode includes a negative electrode active material comprising a spinel titanium oxide and a negative current collector including aluminum or an aluminum alloy, said negative current collector contacting said non-aqueous electrolyte on both sides of said negative electrode;

said non-aqueous electrolyte includes a solvent;

said solvent includes 50 vol % or more of acetonitrile;

said unit cell further includes a third metal electrode; and

said third metal electrode includes at least one selected from the group consisting of nickel, copper, iron, and stainless steel.

14. 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, a positive electrode capacity being greater than a negative electrode capacity,

wherein said positive electrode includes a positive electrode active material comprising a spinel lithium composite oxide represented by the general formula:

Li 1+x Mn 2−x−y A y O 4

where A is Al and at least one selected from the group consisting of Ni and Fe, 0≦x≦⅓, and 0≦y≦0.6, and a positive current collector including aluminum or an aluminum alloy, said positive current collector contacting said non-aqueous electrolyte on both sides of said positive electrode;

said negative electrode includes a negative electrode active material comprising a lithium-containing titanium oxide represented by the general formula:

Li 3+3x Ti 6−3x O 12

where 0≦x≦⅓and a current collector including aluminum or an aluminum alloy, said negative current collector contacting said non-aqueous electrolyte on both sides of said negative electrode;

said non-aqueous electrolyte includes a solvent;

said solvent includes 50 vol % or more of acetonitrile;

said unit cell further includes a third metal electrode; and

said third metal electrode includes at least one selected from the group consisting of nickel, copper, iron, and stainless steel.

15. The non-aqueous electrolyte secondary battery in accordance with claim 1 , further comprising a gas releasing valve.

16. The non-aqueous electrolyte secondary battery in accordance with claim 13 , further comprising a gas releasing valve.

17. The non-aqueous electrolyte secondary battery in accordance with claim 14 , further comprising a gas releasing valve.

18. The non-aqueous electrolyte secondary battery in accordance with claim 15 , wherein

said gas releasing valve is resettable, and has a structure that enables refilling said non-aqueous electrolyte when said non-aqueous electrolyte is decreased by gasification of acetonitrile.

19. The non-aqueous electrolyte secondary battery in accordance with claim 16 , wherein

said gas releasing valve is resettable, and has a structure that enables refilling said non-aqueous electrolyte when said non-aqueous electrolyte is decreased by gasification of acetonitrile.

20. The non-aqueous electrolyte secondary battery in accordance with claim 17 , wherein

said gas releasing valve is resettable, and has a structure that enables refilling said non-aqueous electrolyte when said non-aqueous electrolyte is decreased by gasification of acetonitrile.

21. A non-aqueous electrolyte secondary battery comprising a unit cell including a sheet-shaped first electrode, a sheet-shaped second electrode, a separator disposed between said first electrode and said second electrode, and a nonaqueous electrolyte, wherein:

said non-aqueous electrolyte contains acetonitrile or propionitrile as a solvent,

said first electrode is a positive electrode including a positive electrode active material and a positive current collector including aluminum or an aluminum alloy, said positive current collector contacting said non-aqueous electrolyte on both sides of said positive electrode,

said second electrode is a negative electrode including a lithium-containing titanium oxide as a negative electrode material and a negative current collector including aluminum or an aluminum alloy, said negative current collector contacting said non-aqueous electrolyte on both sides of said negative electrode,

a positive electrode capacity is greater than a negative electrode capacity,

at least a portion of said acetonitrile or propionitrile is capable of being gasified during the overcharging of said battery,

said unit cell further includes a third metal electrode, and

said third metal electrode includes at least one selected from the group consisting of nickel, copper, iron, and stainless steel.