▎ 摘　　要

NOVELTY - An ionic liquid (I) is new. USE - New ionic liquid is used for mixed ionic liquid for manufacture of graphene dispersion liquid (all claimed), and electronic component and energy storage electrical appliances e.g. lithium ion secondary battery. ADVANTAGE - The new ionic liquid has high dispersibility. The new ionic liquid enables formation of graphene dispersion liquid having high concentration, with high productivity. DETAILED DESCRIPTION - An ionic liquid of formula (I) is new. R1,R5=optionally substituted 1-7C linear or branched alkyl; R2=1-10C alkylene, or group of formula (i) or (ii); Ar'=arylene; R6a,R6b=1-4C alkylene; R7a,R7b=1-4C alkylene; R8a,R8b=1-4C alkylene; m,m'=1-10; R3,R4=H or optionally substituted 1-4C linear or branched alkyl; X-=counter-ion;and n=0-30. INDEPENDENT CLAIMS are included for the following: (1) mixed ionic liquid, which contains ionic liquid (A) (I) and butyl methyl imidazolium hexafluorophosphate (B), or butyl methyl imidazolium bis (trifluoromethanesulfonyl) imide (C); (2) graphene dispersion liquid, which contains graphene and ionic liquid (I), or mixed ionic liquid; and (3) preparation of graphene dispersion liquid, which involves adding graphite to ionic liquid (I), or mixed ionic liquid, and applying ultrasonic wave or microwave to the liquid mixture.