Patent ID: 7471502

Claim:
An electrical double-layer capacitor having: a pair of polarizable electrodes, a separator between the polarizable electrodes and a liquid electrolyte for electrical storage devices comprising an electrolyte salt having general formula (1) below, wherein R 1 to R 4 are each independently an alkyl of 1 to 5 carbons or an alkoxyalkyl of the formula R′—O—(CH 2 ) n —, R′ being methyl or ethyl and the letter n being an integer from 1 to 4, and any two from among R 1 , R 2 , R 3 and R 4 may together form a ring, with the proviso that at least one of groups R 1 to R 4 is an alkoxyalkyl of the above formula; X is a nitrogen or phosphorus atom; and Y is a monovalent anion.