Facile synthesis of N, S-modified activated carbon from biomass residue for promising supercapacitor electrode applications

This study used hydrothermal carbonization and activation methods to synthesize N, S modified activated carbon (NS-ACA) from biomass residue for supercapacitor electrode application. The process involves calcium chloride as an activating agent and ammonium persulfate as sources of nitrogen and sulfur. The NS-ACA sample's mesoporous structure and specific surface area were 2.9–8.9 nm in diameter and 364.0–677.5 m2∙g−1. The electrochemical analysis revealed that the NS-ACA3 sample is the best result, with a specific capacitance value of 173.91 F∙g−1 at 0.5 A∙g−1. The optimum energy and power density values were 5.11 Wh∙kg−1 and 230.0 W∙kg−1, respectively, with a current of 0.5 A∙g−1. The supercapacitor's coulombic efficiency and capacitance retentions were 100 % and 98 %, following 5000 cycles of cyclic charge-discharge testing. The present preparation method is a simple, unique, and promising routine to synthesize dual heteroatoms carbon materials from biomass for high-performance supercapacitors.