Two-step pyrolysis of mango branch for the preparation of B/N/O co-doped porous carbon materials

Abstract

Porous carbon prepared by conventional pyrolysis of forestry waste usually possesses poor specific capacitance as supercapacitor electrodes, which mainly attributes to the shortcomings of its poor microstructure and few chemical functional groups on the surface. It is suggested that the introduction of active groups can enhance the wettability and induce redox reactions, thereby increasing the specific capacitance. In this paper, novel functional carbon materials with high electrochemical activity were effectively prepared from forestry waste by a green and economical B/N/O co-doping synthesis strategy using NH4B5O8 as bi-functional additive. The doped content of heteroatoms, specific surface area, and pore features were controlled by adjusting the NH4B5O8 mixing ratio and pyrolysis temperature. MA3-T700 showcases a specific surface area of 1621 m2/g, preferable B/N/O atoms doped content (0.62%, 1.98%, and 13.82%, respectively), and interconnected micropores/mesopores structure. It exhibits an ultra-high specific capacitance of 322 F/g at 1 A/g and an exceptional rate performance of 77.02% even at 20 A/g. Furthermore, MA3-T700 symmetric supercapacitor was assembled, exhibiting an impressive capacitance retention of 96.11% after 10,000 cycles and achieving an energy density of 8.4 Wh/kg. This work provides technical and theoretical support for the utilization of high-value resources from forestry waste.