High volumetric performance of functional carbon material enabled by co-pyrolysis of mango branches and Faradaic active N-enriched doping

Abstract

Restricted by the poor volumetric performance, biomass-based supercapacitors are challenging to meet the rapid development of miniaturization and portability of energy storage devices, and the Faraday active nitrogen-doping strategy proves to be an efficient approach to address this concern. This study successfully synthesizes functional carbon materials with significant Faraday activity through a straightforward and environmentally friendly co-pyrolysis method. Mango branches served as the primary raw material, NH4B5O8∙4H2O acted as a template, and NH4Cl and NH4B5O8∙4H2O were utilized as the multiple nitrogen-enriched agents. A surface micro-NH3 environment can be achieved by modulating the addition of NH4Cl, and the decomposed NH3 is adsorbed on the biomass surface by the electrostatic adsorption of NH4B5O8∙4H2O. MA1.5N1.5-T700 showcases a compact self-supported structure with micro/mesopores, boasting a substantial nitrogen content of 2.95 %. It achieves a notable volumetric capacitance of 320 F/cm3 (368 F/g) at 0.5 A/g and maintains an exceptional rate performance of 72.9 % at 20 A/g. The constructed symmetrical supercapacitor also reveals an ultra-high energy density of 13.01 Wh/L (14.95 Wh/kg) and an impressive capacitance retention of 94.03 % undergoing 10,000 cycles. This study offers theoretical insights into fabricating electrode materials for high volumetric energy density supercapacitors through the pyrolysis of forestry waste.