Highly porous carbon nanofoams synthesized from gas-phase plasma for symmetric supercapacitors

Highly porous carbon nanofoams (CNFs) could be massively synthesized at room temperature from acetylene gas precursor by a plasma-enhanced chemical vapor deposition technique. The synthesized CNFs had a three-dimensional framework structure composed of aggregations of nano-sized spherical carbon particles, in which the open-connected micron-and nano-pores were hierarchically distributed. Afterwards, thermal treatment and nitrogen doping process were conducted to enhance both electrical conductivity and electrochemical properties of the CNFs. The nitrogen-doped CNFs (N-CNFs) exhibited very high specific surface area of up to 920.4 m(2) g(-1) and a pore volume of approximately 0.70 cm(3) g(-1). Due to their hierarchical porous structure, large ion-accessible surface area, and good conductivity for fast ion sorption and electron transfer, the N-CNFs exhibited excellent electrochemical performance for supercapacitor application, such as high specific capacitance of 362.6F g-1 at a current density of 1 A g(-1) and super stability in cycle life test. In addition, a symmetric supercapacitor assembled with N-CNFs could deliver a maximum energy density of 24.4 Wh kg(-1) and a power density of 8.8 kW kg(-1).