Nitrogen-/Boron-Doped Carbon from Poplar Powder and Carbon Nanotube Composite as Electrode Material for Supercapacitors

This study presents a relatively easy method to use bioderived carbon material from poplar and carbon nanotubes as electrode materials in supercapacitors. After delignification, poplar powder was intercalated with acidized multiwalled carbon nanotubes, boric acid, and melamine. Subsequently, after carbonization and activation treatment, electrode materials in a supercapacitor exhibiting high electrochemical characteristics were prepared. The obtained multistage porous carbon material achieved a pore volume reaching 0.86 cm3 g–1 as well as a specific surface area reaching 1500.5 m2 g–1. The specific capacitance reached >432.31 F g–1, and the capacitance retention rate was still 95.7% after 3000 cycles of charge and discharge under a current density of 0.5 A g–1. A good power density was achieved by the symmetrical supercapacitor in 6 M KOH electrolyte (11.67 W h kg–1 at 300 W kg–1, 7.74 W h kg–1 at 1485 W kg–1) as well as a remarkable cycle stability (88.3% capacitance retention after 5000 cycles).