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

Abstract

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 2898m2g−1 with a pore volume of 1.59cm3g−1 (30% mesopores) is successfully achieved in a 3-dimensional HPAC. As a supercapacitor electrode combined with a 6M KOH electrolyte, a high specific capacitance of 266Fg−1 at a current of 0.1Ag−1 is successfully achieved and an excellent rate performance up to 76% of its capacitance is retained at a high current of 100Ag−1. Additionally, in EMIMBF4 electrolyte, 3-dimensional HPAC electrode exhibit a high capacitance of 155Fg−1 at 0.1Ag−1 and 142Fg−1 at 10Ag−1. Owing to its excellent rate performance, 3-dimensional HPAC can deliver a high energy density of 53Whkg−1 and a high power density of 8224Wkg−1, which shows promising application potential in energy storage devices.