A high-voltage asymmetric electrical double-layer capacitors using propylene carbonate

•Carbon black with low O content reduce their oxidative activity in propylene carbonate.•The carbon black/propylene carbonate interface can reach 1 V against Ag/AgNO3.•An asymmetric supercapacitor with a high cell voltage of 3 V is constructed.

The upper limit of the double-layer potential window for the propylene carbonate/carbon black interface is effectively extended from 0.1 to 1 V (vs. Ag/AgNO3), compared with activated carbon. Commercial carbon black with low defects and activated carbon are respectively employed as positive and negative electrode materials to construct an advanced asymmetric supercapacitor with cell voltage reaching 3 V in propylene carbonate. This asymmetric supercapacitor of the double-layer type with a cell voltage of 3 V is very stable in 10,000-cycle charge-discharge tests.