Nitrogen-Doped Foam-like Carbon Plate Consisting of Carbon Tubes as High-Performance Electrode Materials for Supercapacitors

A nitrogen-doped foam-like 3D carbon plate is prepared by carbonizing a selected biomass precursor of pomelo peel. The carbon plate is composed of interwoven connected carbon tubes and shows a unique 3D interpenetrating macroporous network with binary-channel structure. Owing to the proper pore structures, short ion-diffusion paths, high conductivity, and high structure stability, the carbon plate exhibits excellent electrochemical performance as an electrode for supercapacitors directly. A high specific capacitance of up to 338 Fg(-1) at 1 Ag-1, good rate capability with a capacitance retention of 59% at 20 Ag-1, and high cycling stability with only 4% capacitance loss after 5000 cycles at 20 Ag-1 can be achieved in 6 M KOH electrolyte in a three-electrode system. Furthermore, a symmetric supercapacitor fabricated by using the carbon plates delivers an energy density of 11.05 Wh kg(-1) at a power density of 250 W kg(-1), and an outstanding cycling stability with only 2.4% capacitance decay over 5000 cycles at 5 Ag-1 in 6 M KOH electrolyte. These very attractive electrochemical properties indicate that the carbon plate derived from pomelo peel is a promising electrode material for supercapacitors.