Nonaqueous electrolytic solution and energy storage device using same

1. A nonaqueous electrolytic solution comprising:

(i) an electrolyte salt;

(ii) a nonaqueous solvent, comprising ethylene carbonate, propylene carbonate, or both, in a total amount of 3 to 45 volume % based on the volume of the nonaqueous solvent;

(iii) LiPF 2 (—OC(═O)—C(═O)O—) 2 ; and

(iv) at least one compound represented by formula (I):

wherein R 1 and R 2 each independently represent a hydrogen atom or an alkyl group having from 1 to 6 carbon atoms and optionally substituted with a halogen atom; and R 3 represents a methyl group or an ethyl group, X represents a hydrogen atom or —CR 1 R 2 —OS(═O) 2 —R 3 , and

wherein a content of LiPF 2 (—OC(═O)—C(═O)O—) 2 is 0.001 to 4 mass % in the nonaqueous electrolytic solution, and a content of the compound represented by the formula (I) is 0.001 to 5 mass % in the nonaqueous electrolytic solution.

2. The nonaqueous electrolytic solution as set forth in claim 1 , wherein R 3 in said compound represented by the general formula (I) is a methyl group.

3. The nonaqueous electrolytic solution as set forth in claim 1 , wherein R 1 and R 2 in said compound represented by the general formula (I) are a hydrogen atom.

4. The nonaqueous electrolytic solution as set forth in claim 1 , wherein said compound represented by the general formula (I) is 2-propynyl methane sulfonate or 2-butyne-1,4-diyldimethane sulfonate.

5. The nonaqueous electrolytic solution as set forth in claim 1 , wherein the electrolyte salt comprises LiPO 2 F 2 .

6. The nonaqueous electrolytic solution as set forth in claim 5 , wherein the content of LiPO 2 F 2 in the nonaqueous electrolytic solution is 0.001 to 0.4M.

7. The nonaqueous electrolytic solution as set forth in claim 1 , further comprising at least one compound represented by the formula (II):

wherein L represents an alkylene group having from 1 to 6 carbon atoms.

8. The nonaqueous electrolytic solution as set forth in claim 7 , wherein a content of said compound represented by the formula (II) is 0.001 to 10 mass % in the nonaqueous electrolytic solution.

9. The nonaqueous electrolytic solution as set forth in claim 7 , wherein said compound represented by the general formula (II) is adiponitrile.

10. The nonaqueous electrolytic solution as set forth in claim 1 , wherein said nonaqueous solvent further comprises a chain ester.

11. The nonaqueous electrolytic solution as set forth in claim 10 , wherein said chain ester is at least one selected from the group consisting of methylethyl carbonate, methylpropyl carbonate, methylisopropyl carbonate, methylbutyl carbonate, ethylpropyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, a pivalic acid ester, methyl propionate, ethyl propionate, methyl acetate and ethyl acetate.

12. The nonaqueous electrolytic solution as set forth in claim 1 , wherein said nonaqueous solvent further comprises at least one additional cyclic carbonate selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, 4-ethynyl-1,3-dioxolane-2-one, 4-fluoro-1,3-dioxolane-2-one, trans- or cis-4,5-difluoro-1,3-dioxolane-2-one, 1,2-butylene carbonate and 2,3-butylene carbonate.

13. The nonaqueous electrolytic solution as set forth in claim 12 , wherein said additional cyclic carbonate comprises:

(a) at least one cyclic carbonate selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, and 4-ethynyl-1,3-dioxolane-2-one,

and

(b) at least one cyclic carbonate selected from the group consisting of 4-fluoro-1,3-dioxolane-2-one, and trans- or cis-4,5-difluoro-1,3-dioxolane-2-one.

14. The nonaqueous electrolytic solution as set forth in claim 1 , wherein said electrolyte salt is a lithium salt.

15. The nonaqueous electrolytic solution as set forth in claim 1 , wherein said electrolyte salt is at least one selected from the group consisting of LiPF 6 , LiBF 4 , LiPO 2 F 2 , and LiB(—OC(═O)—C(═O)O—) 2 .

16. The nonaqueous electrolytic solution as set forth in claim 1 , wherein the concentration of the electrolyte salt is 0.5 to 2.5 M with respect to said nonaqueous solvent.

17. An energy storage device comprising a positive electrode, a negative electrode and the nonaqueous electrolytic solution of claim 1 .

18. The energy storage device as set forth in claim 17 , wherein said positive electrode comprises at least one selected from the group consisting of lithium complex metal oxides and lithium-containing olivine-type phosphoric acid salts as a positive electrode active material.

19. The energy storage device as set forth in claim 17 , wherein said negative electrode comprises at least one selected from the group consisting of lithium metal, lithium alloy, carbon materials which can absorb and release lithium, and metal compounds which can absorb and release lithium as a negative electrode active material.