Nitrogen-Doped Graphene for Ionic Liquid Based Supercapacitors

Graphene is a promising electrode material for supercapacitor applications due to its unique properties. Interaction of electrolyte ions with graphene lattice sites is a crucial factor in ionic liquid electrolyte based supercapacitors. In an effort to increase the interaction of high viscous electrolyte with electrode material, here, we here report the results of a systematic study carried out on a supercapacitor with nitrogen doped graphene as electrode material and [BMIM][TFSI] as electrolyte. In this study, nitrogen doped hydrogen exfoliated graphene (N-HEG) is prepared by radio frequency (R.F) magnetron sputtering and employed as electrode material for [BMIM][ITSI] electrolyte based high performance supercapacitor. N-HEG shows a high specific capacitance of 170.1 F/g compared to that of electrolyte modified graphene (124.5 F/g), at a specific current of 2 A/g. The improved performance of N-HEG based supercapacitor is attributed to the presence of nitrogen atoms in the graphene lattice which in turn increases the lattice-ion interaction and the electrical conductivity. In addition, the presence of wrinkles on the graphene surface provides a shortest directional path to access pores and surface. The device shows high charge storage capacity (72.37 Wh/kg) along with wide operating voltage (3.5 V) and high cyclic stability.