Non-aqueous electrolyte for secondary battery and non-aqueous electrolyte secondary battery employing the same

1. A non-aqueous electrolyte solution for a non-aqueous electrolyte secondary battery that has a positive electrode and a negative electrode capable of the absorbing and releasing of a metal ion, and a separator,

the non-aqueous electrolyte solution comprising:

an electrolyte,

a non-aqueous solvent, and

0.01 mass % to less than 3 mass % of a compound comprising a partial structure of formula (1) and at least two isocyanate groups:

wherein

R is hydrogen or a C 1 -C 12 organic group comprising an atom selected from the group consisting of hydrogen atom, carbon atom, nitrogen atom, oxygen atom, sulfur atom, phosphorus atom, and halogen atom, and

wherein the C 1 -C 12 organic group optionally comprises an isocyanate group.

2. The non-aqueous electrolyte solution according to claim 1 , wherein the compound comprising a partial structure of formula (1) is a compound comprising at least one skeleton selected from the group consisting of uretdione, oxadiazinetrione, biuret, urethane, allophanate, and isocyanurate.

3. The non-aqueous electrolyte solution according to claim 1 , wherein a number-average molecular weight of the compound comprising a partial structure of formula (1) is from 300 to 5000.

4. The non-aqueous electrolyte solution according to claim 1 , further comprising 0.5 to 3 mol/L lithium hexafluorophosphate (LiPF 6 ).

5. The non-aqueous electrolyte solution according to claim 1 , further comprising a compound selected from the group consisting of monofluorophosphate salts, difluorophosphate salts, tetrafluoroborate salts, and compounds of formulas (2) to (5):

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

wherein l and m are each independently integers from 0 to 4;

LiC n F 2n+1 SO 3   (3)

wherein n is an integer from 0 to 4;

M a 1 [M 2 (C 2 O 4 ) b R c ] d   (4)

wherein M 1 is an element selected from Groups 1 and 2 of the Periodic Table, and aluminum (Al); M 2 is an element selected from the transition metals and Groups 13, 14, and 15 of the Periodic Table; R is a group selected from halogens, C 1 -C 11 alkyl groups, and C 1 -C 11 halogen-substituted alkyl; a and b are positive integers; c is 0 or a positive integer; and d is an integer from 1 to 3;

wherein M 3 is a metal atom, a phosphorus atom, a boron atom, or P═O. R 1 is a C 1 -C 11 alkyloxy group, a silyloxy group, or a C 1 -C 11 alkylsilyloxy group. n is the number of R 1 groups bonded to the M 3 with the proviso that when n is two or more, the R 1 groups may be the same or may differ from one another, R 2 to R 4 are each independently a C 1 -C 11 alkyl group, a C 1 -C 11 alkenyl group, a C 1 -C 11 alkyloxy, or a C 6 -C 11 aryl group).

6. The non-aqueous electrolyte solution according to claim 5 , comprising a compound of formula (4) in which M 1 is lithium and M 2 is phosphorus or boron.

7. The non-aqueous electrolyte solution according to claim 5 , comprising a compound of formula (5) in which M 3 is boron or P═O.

8. The non-aqueous electrolyte solution according to claim 5 , wherein a content of the compound selected from the group consisting of monofluorophosphate salts, difluorophosphate salts, tetrafluoroborate salts, and compounds represented by the general formulas (2) to (5) is from 0.01 to 5 mass % of the non-aqueous electrolyte solution.

9. The non-aqueous electrolyte solution according to claim 5 , wherein the compound selected is at least one selected from the group consisting of lithium monofluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium fluorosulfonate, lithium trifluoromethanesulfonate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate, tris(trimethylsilyl) borate, and tris(trimethylsilyl) phosphate.

10. The non-aqueous electrolyte solution according to claim 1 , further comprising a compound selected from the group consisting of unsaturated cyclic carbonates, fluorinated cyclic carbonates, and dinitrile compounds of formula (6):

wherein A is a C 1 -C 10 organic group comprising an atom selected from the group consisting of hydrogen atom, carbon atom, nitrogen atom, oxygen atom, sulfur atom, phosphorus atom, and halogen atom.

11. The non-aqueous electrolyte solution according to claim 1 , for a non-aqueous electrolyte secondary battery, wherein the secondary battery comprises a separator comprising at least one of polyethylene and polypropylene.

12. The non-aqueous electrolyte solution according to claim 1 , for a non-aqueous electrolyte secondary battery, wherein the secondary battery comprises carbon as a negative electrode active material.

13. A non-aqueous electrolyte secondary battery comprising: a positive electrode and a negative electrode which are capable of the absorbing and releasing of a metal ion; a separator; and the non-aqueous electrolyte solution according to claim 1 .

14. The non-aqueous electrolyte secondary battery according to claim 13 , which comprises carbon as a negative electrode active material, wherein a Raman R value of the carbon is 0.1 or more;

wherein, the Raman R value is defined as a ratio, in argon laser Raman spectroscopy, of the peak intensity at 1360 cm −1 to the peak intensity at 1580 cm −1 .