Graphene and carbon nanotube composite electrodes for supercapacitors with ultra-high energy density

• DOI: 10.1039/c1cp21910c
• Publication Date: 2011-09-02T08:33:31Z
• Authors: Qian Cheng; Jie Tang; Jun Ma; Han Zhang; Norio Shinya; Lu-Chang Qin
• Keywords: Models, Molecular; Nanotubes, Carbon; Surface Properties; Graphite; 02 engineering and technology; Particle Size; 0210 nano-technology; Electrodes; 7. Clean energy

We describe a graphene and single-walled carbon nanotube (SWCNT) composite film prepared by a blending process for use as electrodes in high energy density supercapacitors. Specific capacitances of 290.6 F g(-1) and 201.0 F g(-1) have been obtained for a single electrode in aqueous and organic electrolytes, respectively, using a more practical two-electrode testing system. In the organic electrolyte the energy density reached 62.8 Wh kg(-1) and the power density reached 58.5 kW kg(-1). The addition of single-walled carbon nanotubes raised the energy density by 23% and power density by 31% more than the graphene electrodes. The graphene/CNT electrodes exhibited an ultra-high energy density of 155.6 Wh kg(-1) in ionic liquid at room temperature. In addition, the specific capacitance increased by 29% after 1000 cycles in ionic liquid, indicating their excellent cyclicity. The SWCNTs acted as a conductive additive, spacer, and binder in the graphene/CNT supercapacitors. This work suggests that our graphene/CNT supercapacitors can be comparable to NiMH batteries in performance and are promising for applications in hybrid vehicles and electric vehicles.