▎ 摘　　要

Pores and surface functional groups are created on graphene nanosheets (GNSs) to improve supercapacitor properties in a butylmethylpyrrolidinium-dicyanamide (BMP-DCA) ionic liquid (IL) electrolyte. The GNS electrode exhibits an optimal capacitance of 330 Fg(-1) and a satisfactory rate capability within a wide potential range of 3.3 V at 25 degrees C. Pseudocapacitive effects are confirmed using X-ray photoelectron spectroscopy. Under the same conditions, carbon nanotube and activated carbon electrodes show capacitances of 80 and 81 Fg(-1), respectively. Increasing the operation temperature increases the conductivity and decreases the viscosity of the IL electrolyte, further improving cell performance. At 60 degrees C, a symmetricelectrode GNS supercapacitor with the IL electrolyte is able to deliver maximum energy and power densities of 140 Whkg(-1) and 52.5 kWkg(-1) (based on the active material on both electrodes), respectively, which are much higher than the 20 Whkg(-1) and 17.8 kWkg(-1) obtained for a control cell with a conventional organic electrolyte.