Non-aqueous electrolyte secondary battery

1. A non-aqueous electrolyte secondary battery comprising: a positive electrode comprising a positive electrode mixture; a negative electrode comprising a negative electrode mixture; and a non-aqueous electrolyte,

wherein said negative electrode mixture includes a material capable of absorbing and desorbing Li and a carbon material,

said material capable of absorbing and desorbing Li includes at least one element selected from the group consisting of Si and Sn,

the amount of said carbon material is 3 to 60% by weight of said negative electrode mixture,

at least one of said positive electrode, said negative electrode, and said non-aqueous electrolyte contains a lithium perfluoroalkylsulfonyl imide represented by the following general formula (1):

LiN(C m F 2m+1 SO 2 )(C n F 2n+1 SO 2 )  (1)

where m and n each represent an integer of 1 to 5 and may be m=n, and

the ratio of the total weight of said lithium perfluoroalkylsulfonyl imide contained in at least one of said positive electrode, said negative electrode, and said non-aqueous electrolyte to the weight of said carbon material is 10 −3 to 10.

2. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said lithium perfluoroalkylsulfonyl imide is at least one selected from the group consisting of LiN(CF 3 SO 2 ) 2 and LiN(C 2 F 5 SO 2 ) 2 .

3. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said carbon material is carbon nanofibers.

4. The non-aqueous electrolyte secondary battery in accordance with claim 3 , wherein said carbon nanofibers are bonded to a surface of said material capable of absorbing and desorbing Li, and a catalytic element for promoting the growth of said carbon nanofibers is carried on the surface of said material capable of absorbing and desorbing Li or an end of said carbon nanofibers.

5. The non-aqueous electrolyte secondary battery in accordance with claim 4 , wherein said carbon nanofibers account for 5 to 70% by weight of the total of said carbon nanofibers, said material capable of absorbing and desorbing Li, and said catalytic element.

6. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said lithium perfluoroalkylsulfonyl imide is contained in at least said negative electrode.

7. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said material capable of absorbing and desorbing Li is at least one oxide selected from the group consisting of SiO x and SnO y where O<x<2 and O<y≦2.

8. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein

at least said non-aqueous electrolyte contains said lithium perfluoralkylsulfonyl imide, and

the concentration of said lithium perfluoralkylsulfonyl imide in said non-aqueous electrolyte is less than 1 mol/L.

9. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein

said non-aqueous electrolyte contains at least one supporting salt selected from the group consisting of LiPF 6 , LiBF 4 , and LiAsF 6 , and an additive, and

said additive is said lithium perfluoralkylsulfonyl imide.