Nitrogen-doped porous carbon derived from rapeseed residues for high-performance supercapacitors

Abstract

In this paper, nitrogen-doped activated carbons obtained from rapeseed residues (N-RCs) as supercapacitor electrodes are successfully synthesized by a simple chemical activation method. The field emission scanning microscope, transmission electron microscopy, and N2 adsorption-desorption tests demonstrate that N-RCs treated with ZnCl2 can produce a large number of mesopores. Additionally, the N-RCs have certain amount of nitrogen (nitrogen content in N-RC2 is 6.55% by element content analysis). As the electrode material, N-RC2 exhibits ideal capacitive behavior in 6 mol L-1 KOH aqueous electrolyte in a three-electrode system tests, and the maximum specific capacitance reaches 250 F g-1 at a current density of 0.5 A g-1. Furthermore, in 0.5 mol L-1 Na2SO4 aqueous electrolyte, the as-assembled N-RC2//N-RC2 symmetric cell exhibits high energy density of 13.55 Wh kg-1 at a power density of 399.80 W kg-1 operated at the voltage range of 0 to 1.8 V and an excellent cycleability retaining about 92.8% initial capacitance after 5000 cycles.