Non-aqueous electrolyte for secondary battery and non-aqueous electrolyte secondary battery

1. A non-aqueous electrolyte for secondary battery comprising a non-aqueous solvent dissolving lithium salt of an electrolyte,

wherein the non-aqueous solvent contains: chain fluorinated carboxylic acid ester represented by the below formula (1), and a film forming chemical compound decomposed in the range of +1.0 to 3.0 V based on an equilibrium potential between metal lithium and lithium ion:

CH 3 COOCH 2 CH 3-x F x   (1)

wherein in the above formula (1), x is 2 or 3.

2. The non-aqueous electrolyte for secondary battery as claimed in claim 1 , wherein said chain fluorinated carboxylic acid ester is 2,2-difluoroethyl acetate CH 3 COOCH 2 CHF 2 .

3. The non-aqueous electrolyte for secondary battery as claimed in claim 1 , wherein said film forming chemical compound is at least one selected from 4-fluoroethylene carbonate and its derivatives, ethylene sulfite and its derivatives, vinyl ethylene carbonate and its derivatives, LiB(C 2 O 4 ) 2 , and LiBF 2 (C 2 O 4 ).

4. The non-aqueous electrolyte for secondary battery as claimed in claim 3 , wherein said film forming chemical compound is 4-fluoroethylene carbonate.

5. The non-aqueous electrolyte for secondary battery as claimed in claim 4 , wherein the content of said 4-fluoroethylene carbonate is in the range of 5 to 30 volume % to the whole amount of non-aqueous solvent.

6. The non-aqueous electrolyte for secondary battery as claimed in claim 2 , wherein said film forming chemical compound is at least one selected from 4-fluoroethylene carbonate and its derivatives, ethylene sulfite and its derivatives, vinyl ethylene carbonate and its derivatives, and LiB(C 2 O 4 ) 2 and LiBF 2 (C 2 O 4 ).

7. The non-aqueous electrolyte for secondary battery as claimed in claim 2 , wherein said film forming chemical compound is 4-fluoroethylene carbonate.

8. The non-aqueous electrolyte for secondary battery as claimed in claim 7 , wherein the content of said 4-fluoroethylene carbonate is in the range of 5 to 30 volume % to the whole amount of non-aqueous solvent.

9. The non-aqueous electrolyte for secondary battery as claimed in claim 2 , wherein the content of said chain fluorinated carboxylic acid ester is in the range of 5 to 90 volume % to the whole amount of non-aqueous solvent.

10. The non-aqueous electrolyte for secondary battery as claimed in claim 7 , wherein the content of said 2,2-difluoroethyl acetate CH 3 COOCH 2 CHF 2 is in the range of 5 to 90 volume % to the whole amount of non-aqueous solvent.

11. The non-aqueous electrolyte for secondary battery as claimed in claim 9 , wherein the content of said chain fluorinated carboxylic acid ester is in the range of 20 to 80 volume % to the whole amount of non-aqueous solvent.

12. The non-aqueous electrolyte for secondary battery as claimed in claim 10 , wherein the content of said 2,2-difluoroethyl acetate CH 3 COOCH 2 CHF 2 is in the range of 20 to 80 volume % to the whole amount of non-aqueous solvent.

13. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, wherein said non-aqueous electrolyte is the non-aqueous electrolyte for secondary battery as claimed in claim 1 .

14. The non-aqueous electrolyte for secondary battery as claimed in claim 1 ,

wherein said chain fluorinated carboxylic acid ester is 2,2,2-trifluoroethyl acetate CH 3 COOCH 2 CF 3 .

15. The non-aqueous electrolyte for secondary battery as claimed in claim 3 ,

wherein said chain fluorinated carboxylic acid ester is 2,2,2-trifluoroethyl acetate CH 3 COOCH 2 CF 3 .

16. The non-aqueous electrolyte for secondary battery as claimed in claim 4 , wherein said chain fluorinated carboxylic acid ester is 2,2,2-trifluoroethyl acetate CH 3 COOCH 2 CF 3 .

17. The non-aqueous electrolyte for secondary battery as claimed in claim 5 ,

wherein said chain fluorinated carboxylic acid ester is 2,2,2-trifluoroethyl acetate CH 3 COOCH 2 CF 3 .

18. A non-aqueous electrolyte for secondary battery comprising a non-aqueous solvent dissolving lithium salt of an electrolyte,

wherein the non-aqueous solvent contains: chain fluorinated carboxylic acid ester represented by a formula (1) CH 3 COOCH 2 CH 3-x F x wherein x is 2 or 3;

and a film-forming chemical compound decomposed in the range of +1.0 to 3.0 V based on an equilibrium potential between metal lithium and lithium ion;

wherein the film forming chemical compound contains:

(2) 4-fluoroethylene carbonate; and

(3) at least one selected from ethylene sulfite, vinyl ethylene carbonate, LiB(C 2 O 4 ) 2 , and LiBF 2 (C 2 O 4 ).

19. The non-aqueous electrolyte for secondary battery as claimed in claim 18 ,

wherein said chain fluorinated carboxylic acid ester is 2,2-difluoroethyl acetate CH 3 COOCH 2 CHF 2 .

20. The non-aqueous electrolyte for secondary battery as claimed in claim 18 ,

wherein the content of said 4-fluoroethylene carbonate is in the range of 5 to 30 volume % to the whole amount of non-aqueous solvent.

21. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte,

wherein said non-aqueous electrolyte is the non-aqueous electrolyte for secondary battery as claimed in claim 14 .

22. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, wherein said non-aqueous electrolyte is the non-aqueous electrolyte for secondary battery as claimed in claim 18 .

23. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte,

wherein said non-aqueous electrolyte is the non-aqueous electrolyte for secondary battery as claimed in claim 19 .

24. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte,

wherein said non-aqueous electrolyte is the non-aqueous electrolyte for secondary battery as claimed in claim 20 .