A long cycle-life, high-voltage supercapacitor featuring an activated carbon//poly(3-methylthiophene) hybrid configuration with N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid, a solvent-free green electrolyte, was developed. The cyclability of a laboratory scale cell with electrode mass loading sized for practical uses was tested at 60°C over 16,000 galvanostatic charge–discharge cycles at 10mAcm−2 in the 1.5 and 3.6V voltage range. The reported average and maximum specific energy and power, specific capacitance and capacity, equivalent series resistance and coulombic efficiency over cycling demonstrate the long-term viability of this ionic liquid as green electrolyte for high-voltage hybrid supercapacitors.