Nitrogen and sulfur co-doped graphene aerogel for high performance supercapacitors

The development of high energy density and power density supercapacitors is very necessary in energy storage and application fields. A key factor of such devices is high-performance electrode materials. In this work, nitrogen and sulfur co-doped graphene aerogels (N/S-GA) were synthesized using graphene oxide as the precursor and 2-mercapto-1-methylimidazole as both the reducing agent and the N/S doping agent. The pore size distribution of the as-prepared N/S-GA was measured and the N/S-GA possesses a hierarchical porous structure. As an electrode material of supercapacitors, the N/S-GA could provide a suitable structure for charge accommodation and a short distance for ion transport. When 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF₄) ionic liquid was used as the electrolyte, the specific capacitance of the N/S-GA electrode material reached 212 F g^-1 and 162 F g^-1 at the current densities of 1 A g^-1 and 10 A g^-1, respectively. And the energy density and average power density of the N/S-GA based supercapacitor could reach 117 W h kg^-1 and 1.0 kW kg^-1 at 1 A g^-1, 82 W h kg^-1 and 9.5 kW kg^-1 at 10 A g^-1, respectively. It is believed that the N/S-GA material can be used in high-performance supercapacitors.