3-Dimensional hierarchical porous activated carbon derived from coconut fibers with high-rate performance for symmetric supercapacitors

Here we report a 3-dimensional hierarchical porous activated carbon ( HPAC) prepared from coconut fibers with KOH activation, which exhibits high-rate performance for symmetric supercapacitors. At a 4:1 mass ratio of KOH to carbonized coconut fibers, the highest specific surface area of 2898 m(2)g(-1) with a pore volume of 1.59 cm(3)g(-1) (30% mesopores) is successfully achieved in a 3-dimensional HPAC. As a supercapacitor electrode combined with a 6 M KOH electrolyte, a high specific capacitance of 266 Fg(-1) at a current of 0.1 Ag-1 is successfully achieved and an excellent rate performance up to 76% of its capacitance is retained at a high current of 100 Ag-1. Additionally, in EMIMBF4 electrolyte, 3-dimensional HPAC electrode exhibit a high capacitance of 155 F g(-1) at 0.1 A g(-1) and 142 F g(-1) at 10 A g(-1). Owing to its excellent rate performance, 3-dimensional HPAC can deliver a high energy density of 53 Wh kg(-1) and a high power density of 8224 W kg(-1), which shows promising application potential in energy storage devices. (C) 2016 Elsevier Ltd. All rights reserved.