Wrinkled graphene — carbon nanospheres composite for ultra high energy supercapacitors

Abstract

A simple and scalable method is developed to prepare highly wrinkled graphene sheets – carbon nanospheres (WG-CN) composite for ultra high energy density supercapacitor application. Here, we introduce a novel simple paraffin wax candle flame technique for the simultaneous reduction of graphene oxide (GO) and deposition of carbon nanospheres on the graphene sheets. This is followed by introducing permanent wrinkles to the composite. The WG-CN composite exhibit the high specific capacitance values of 290 F g⁻¹ and 253.7 F g⁻¹ (138.5 F cm⁻³) for 6M KOH and EMIMBF₄ ionic liquid electrolytes respectively. The ultra high energy density values of 108 Wh Kg⁻¹ and 58.9 Wh L⁻¹ has been obtained at the power density of 3955 W Kg⁻¹ and 2157 W L⁻¹ simultaneously. These attractive performances exhibited by the WG-CN composite supercapacitor electrode make them potential candidate for future energy storage devices. The key to success of this composite is the ability to make full utilization of the high intrinsic specific surface area of the nanocomposite.