Full capacitance potential of SWCNT electrode in ionic liquids at 4 V

Abstract

We studied the full capacitance potential of single-walled carbon nanotube (SWCNT, 1250 m² g⁻¹) in EMIBF₄ at 4 V by a new charge mode with certain dwelling time at 4 V. This allowed the accessible surface area of SWCNT, in monodispersed state and with macropores in large amount, to be fully explored to exhibit capacitance of 16 μF cm⁻² in a wide range of current density, which is higher than that (9.1 μF cm⁻²) of graphene (5 μm in size and 2200 m² g⁻¹). In situ Raman characterization upon charge and discharge validated the enhanced doping of ions of EMIBF₄ on SWCNT wall with the increased potential. The energy density is found to be 107 W h kg⁻¹ at the power density of 20 kW kg⁻¹, far exceeding that (64 W h kg⁻¹) in conventional galvanostatic charge and discharge mode.