Liquid electrolytes for electrical storage devices

A liquid electrolyte for electrical storage devices comprises an ionic liquid having general formula (1) below and a melting point of up to 50°C wherein R 1 and R 4 are each independently an alkyl of 1 to 5 carbons or an alkoxyalkyl of the formula R'-0-(CH 2 ) n -, R' being methyl or ethyl and the letter n being an integer from 1 to 4, with the proviso that at least one of groups R 1 to R 4 is an alkoxyalkyl of the above formula; and Y is a monovalent anion. It may also include a nonaqueous organic solvent and/or an ion conductive salt.