To provide a non-aqueous electrolyte for an electric double layer capacitor, having high flame retardancy and excellent in cycle characteristics.
The non-aqueous electrolyte for an electric double layer capacitor contains a non-aqueous solvent containing a cyclic phosphagen compound expressed by formula (I) (NPR12)n [R1 is a halogen element, an alkoxyl or aryloxy group, n is 3-4] and a difluorophosphoric acid ester compound expressed by formula (II) [R2 is an alkyl group, a cycloalkyl group, an alkenyl group, or an alkoxy-substituted arkyl or aryl group]; at least one kind of compounds of a compound expressed by formula (III) [R3 is a 1-2C alkyl or phenyl group, R4 is aryl or vinyl group, and R3, R4 may be bond each other to form a ring], and a compound expressed by formula (IV) [R5 is a 1-2C alkyl group, R6 is a 2-4C alkenyl or propargyl group, and R5, R6 may bond each other to form a ring]; and a supporting salt.
OOTSUKI MASAMI
Shiro Fujitani
Kiyoshi Kuruma
Kazuyuki Tomita