NONAQUEOUS ELECTROLYTE, ELECTRICAL DOUBLE LAYER CAPACITORS, AND NONAQUEOUS ELECTROLYTE SECONDARY CELLS

Secondary cells and electrical double-layer capacitors of excellent charge-discharge efficiency, stability and low-temperature properties can be obtained using nonaqueous electrolytes which contain an ionic liquid that has general formula (1) below and is liquid at not higher than 50 DEG C and an ion-conductive polymer. In formula (1), R to R are each independently an alkyl group of 1 to 5 carbons or an alkoxyalkyl group of the formula R'-O-(CH2)n- (R' being methyl or ethyl, and the letter n being an integer from 1 to 4), and any two from among R, R, R and R may together form a ring, with the proviso that at least one of R to R is an alkoxyalkyl group of the above formula. X is a nitrogen atom or a phosphorus atom, and Y is a monovalent anion.