Quaternary ammonium salt, electrolyte, electrolyte, solution and electrochemical device

1. A quaternary ammonium salt of the formula (1)

wherein R 1 is straight-chain or branched alkyl having 1 to 4 carbon atoms, R 2 is straight-chain or branched alkyl having 1 to 3 carbon atoms, and X − is ClBF 3 − , AlF 4 − , or N(SO 2 F) 2 − .

2. A quaternary ammonium salt according to claim 1 wherein R 1 is alkyl having 1 to 2 carbon atoms, R 2 is alkyl having 1 to 2 carbon atoms, and X − is ClBF 3 − , AlF 4 − , or N(SO 2 F) 2 − .

3. A quaternary ammonium salt of the formula (2)

wherein X − is ClBF 3 − , AlF 4 − , or N(SO 2 F) 2 − , and Me is methyl.

4. A quaternary ammonium salt according to claim 3 wherein X − is AlF 4 − or N(SO 2 F) 2 − .

5. A composition wherein the composition comprises at least the quaternary ammonium salt of claim 1 and an organic solvent.

6. A composition according to claim 5 wherein the organic solvent is chain carbonic acid esters.

7. A composition according to claim 6 wherein the chain carbonic acid ester is at least one selected from among ethylmethyl carbonate and dimethyl carbonate.

8. A composition according to claim 7 wherein the chain carbonic acid ester is ethylmethyl carbonate.

9. An electrolytic solution wherein the solution comprises an electrolyte of the formula (3)

wherein R 1 is straight-chain or branched alkyl having 1 to 4 carbon atoms, R 2 is straight-chain or branched alkyl having 1 to 3 carbon atoms, and X— is ClBF 3 − , AlF 4 − , or N(SO 2 F) 2 − .

10. The electrolytic solution of claim 9 wherein the solution comprises an organic solvent.

11. The electrolytic solution according to claim 10 wherein the organic solvent is a chain carbonic acid ester.

12. The electrolytic solution according to claim 11 wherein the chain carbonic acid ester is selected from the group consisting of: ethylmethyl carbonate and dimethyl carbonate.

13. The electrolytic solution according to claim 12 wherein the chain carbonic acid ester is ethylmethyl carbonate.

14. The electrolytic solution according to claim 10 wherein the organic solvent is a cyclic carbonic acid ester.

15. An electrochemical device comprising the electrolytic solution of claim 10 .

16. An electric double-layer capacitor comprising the electrolytic solution of claim 10 .

17. A secondary cell comprising the electrolytic solution of claim 10 .

18. A process for preparing a quaternary ammonium salt of the formula (1)

wherein R 1 is straight-chain or branched alkyl having 1 to 4 carbon atoms, R 2 is straight-chain or branched alkyl having 1 to 3 carbon atoms, and X— is ClBF 3 − , AlF 4 − , or N(SO 2 F) 2 − , comprising

(a) a step of reacting an alkylpyrrolidine of the formula (5) and a compound of the formula (6) to prepare a quaternary ammonium salt of the formula (1a)

(R 1 is same as defined above)

(R 2 is same as defined above and Y Cl, Br or I)

(R 1 , R 2 and Y are same as defined above), and

(b) a step of reacting the quaternaryammonium salt of the formula (1a) and a compound of the formula (7)

MX (7)

(M is hydrogen, alkali metal atom, alkaline-earth metal atom or metal atom, and X − is same as defined above).

19. A process for preparing a quaternary ammonium salt of the formula (9) wherein a quaternary ammonium salt of the formula (8) is reacted with BF 3

wherein R 1 is straight-chain or branched alkyl having 1 to 4 carbon atoms, R 2 is straight-chain or branched alkyl having 1 to 3 carbon atoms, Z is Cl.

20. A process for preparing a quaternary ammonium salt of the formula (11) wherein a quaternary ammonium salt of the formula (10) is reacted with AlF 3

[wherein R 1 is straight-chain or branched alkyl having 1 to 4 carbon atoms, R 2 is straight-chain or branched alkyl having 1 to 3 carbon atoms, Q is F(HF)n (0≦n≦∞)].