Non-aqueous electrolyte secondary battery and assembly thereof

1. A non-aqueous electrolyte secondary battery assembly prior to initial charging, comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte solution, wherein:

the positive electrode has a maximum operating voltage of 4.3 V or higher relative to lithium metal, comprising a positive electrode active material and an ion-conductive inorganic phosphate compound, wherein the positive electrode active material comprises a spinel lithium manganese composite oxide, and

the non-aqueous electrolyte solution comprises a supporting salt, an oxalatoborate-type compound, and a non-aqueous solvent, with the non-aqueous solvent being formed of a non-fluorinated solvent.

2. The non-aqueous electrolyte secondary battery assembly according to claim 1 , wherein the oxalatoborate-type compound is a compound represented by the next general formula (1):

A + [BX 4-2n (C 2 O 4 ) n ] −   (1)

(in the formula (1), A is alkali metal, X is halogen, and n is 1 or 2).

3. The non-aqueous electrolyte secondary battery assembly according to claim 2 , wherein in the general formula (1), A is lithium (Li) and X is fluorine (F).

4. The non-aqueous electrolyte secondary battery assembly according to claim 1 , wherein the oxalatoborate-type compound is lithium difluoro(oxalato)borate (LiDFOB).

5. The non-aqueous electrolyte secondary battery assembly according to claim 1 , wherein the oxalatoborate-type compound content in the entire non-aqueous electrolyte solution is 0.1% by mass or greater, but 5% by mass or less.

6. The non-aqueous electrolyte secondary battery assembly according to claim 1 , wherein the inorganic phosphate compound is a phosphate salt comprising an alkali metal.

7. The non-aqueous electrolyte secondary battery assembly according to claim 1 , wherein the inorganic phosphate compound content is 0.5 part by mass or greater, but 5 parts by mass or less, with the positive electrode active material being 100 parts by mass.

8. The non-aqueous electrolyte secondary battery assembly according to claim 1 , wherein the positive electrode active material comprises a spinel lithium nickel manganese composite oxide.

9. The non-aqueous electrolyte secondary battery assembly according to claim 8 , wherein the spinel lithium nickel manganese composite oxide is a compound presented by the general formula (2):

Li x Ni y Mn 2-y-z M z )O 4-α X 1 q   (2),

wherein M is absent or at least one of a transition metal or main group metal excluding Ni and Mn; x, y, and z are values that satisfy 0.8≦x≦1.2, 0.4<y<1.0, 0≦z, and y+z<2; α is a value that achieves electrical neutrality while satisfying −0.2≦α≦0.2; q meets 0≦q≦1; and when q is larger than 0, X 1 may be F or Cl.

10. The non-aqueous electrolyte secondary battery assembly according to claim 9 , wherein in the general formula (2), y satisfies 0.4<y<0.6.

11. The non-aqueous electrolyte secondary battery assembly according to claim 9 , wherein in the general formula (2), z satisfies 0≦z<1.0.

12. The non-aqueous electrolyte secondary battery assembly according to claim 9 , wherein in the general formula (2) is LiNi 0.5 Mn 1.5 O 4 , LiNi 0.5 Mn 1.45 Ti 0.05 O 4 , LiNi 0.45 Fe 0.05 Mn 1.5 O 4 , or LiNi 0.475 Fe 0.025 Mn 1.475 Ti 0.025 O 4 .

13. The non-aqueous electrolyte secondary battery assembly according to claim 1 , wherein:

the non-fluorinated solvent comprises a cyclic carbonate and an acyclic carbonate,

the cyclic carbonate is one, two or more species selected from a group consisting of ethylene carbonate (EC), vinylene carbonate (VC) and propylene carbonate (PC); and

the acyclic carbonate is one, two or more species selected from a group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC).

14. The non-aqueous electrolyte secondary battery assembly according to claim 1 , wherein the positive electrode is characterized by having an operating voltage of 4.6 V or higher.

15. The non-aqueous electrolyte secondary battery assembly according to claim 1 , wherein the positive electrode active material has an average particle diameter of 20 μm or smaller and a BET specific surface area of about 0.1 m 2 /g to 10 m 2 /g.

16. The non-aqueous electrolyte secondary battery assembly according to claim 1 , wherein the inorganic phosphate compound has an average particle diameter of about 1 μm to 15 μm and a BET specific surface area of suitably about 5 m 2 /g to 50 m 2 /g.

17. The non-aqueous electrolyte secondary battery assembly according to claim 1 , wherein the oxalatoborate-type compound is lithium bis(oxalato)borate (LiBOB).

18. A non-aqueous electrolyte secondary battery obtained by subjecting the non-aqueous electrolyte secondary battery assembly according to claim 1 to at least one cycle of initial charging.