Fabrication of 3D hierarchically structured carbon electrode for supercapacitors by carbonization of polyaniline/carbon nanotube/graphene composites

Composite materials with carbon nanotubes (CNTs) and graphene oxide (GO) are considered to be superior for energy storage applications due to their intriguing structural and electrical properties. The electrochemical performance of CNT/GO-based electrodes can be improved by introducing porous carbon materials into them. Herein, we have carbonized the composite consisted of polyaniline (PANI), GO and CNTs on stainless steel plates and investigated their electrochemical performances as a free-standing and binder-free electrode for supercapacitors. The carbonized PANI with a coral-like nanostructure was formed over CNT and GO surface. Furthermore, the introduction of GO efficiently prevents the excessive agglomeration of PANI in the resultant composite materials. The carbonized composite electrode exhibited the high specific capacitance of 465 mF cm(-2) at a current density of 1 mA cm(-2). Moreover, the carbon electrode obtained by annealing at a higher temperature of 550 degrees C showed the excellent rate capability and cyclic stability. For example, the 78% of initial capacitance retention was observed when the current density changed from 1 mA cm(-2) to 8 mA cm(-2), and the capacitance retention of 84% was achieved after 1000 charge/ discharge cycles. This 3D hierarchically structured carbon electrode can be considered as a potential candidate for next-generation energy storage devices.