Multilayer carbon materials prepared from husk for high-performance supercapacitors.

In this work, porous carbon mixed with nitrogen (NC) prepared using husk as a precursor has been successfully applied in a supercapacitor (SC). The effects of KOH dosage on the structure, composition and capacitive properties of the carbon were investigated by a variety of techniques (SEM, HRTEM, XRD, Raman spectroscopy, XPS, BET, and electrochemical tests). The results of physical characterizations also confirmed that NC had a high specific surface area, abundant pores and a large number of heteroatomic functional groups. Meanwhile, the sample exhibits the best electrochemical performance in a 6 M KOH electrolyte, including high specific capacitance (333.7 F g at a current density of 0.5 A g), desirable rate capability and superior cycling stability (97.9% capacitance retention after 5000 cycles). More importantly, the assembled symmetrical supercapacitor (NC-3//NC-3) holds superior energy density (16.7 W h kg at a power density of 300.6 W kg) and good cycling stability (98.5% specific capacitance retention after 5000 cycles).