Patent ID: 8007680

Claim:
An electrolyte solution for electrochemical device which comprises an imidazolium salt (A) represented by the general formula (1) as a main component and an imidazolium salt (B) represented by the general formula (2), wherein the content of the imidazolium salt (B) represented by the general formula (2) is not more than 15% by weight to the total weight of the imidazolium salt (A) and imidazolium salt (B); (in the formula, R 1 , R 2 and R 3 may be the same or different and each represents an alkyl group containing 1 to 3 carbon atoms; R 4 and R 5 may be the same or different and each represents an hydrogen atom or an alkyl group containing 1 to 3 carbon atoms; and X − represents a counter anion) (in the formula, R 1 , R 3 , R 4 , R 5 and X − are the same as the definition for the general formula (1)).