Sustainable synthesis of N/S-doped porous carbon sheets derived from waste newspaper for high-performance asymmetric supercapacitor

In this work, waste newspaper-derived porous activated carbon (NAC) was prepared using ordinary carbonization and activation route. Then, nitrogen-doped activated carbon (N-NAC) and nitrogen and sulphur co-doped carbon (N/S-NAC) were successfully fabricated by high-temperature calcination method. The electrochemical performance test showed that N/S-NAC electrode displayed higher specific capacitance of 132 Fg^-1 at 1 A g^-1, high rate capability and excellent cyclic stability. An asymmetric supercapacitor (ASC) was assembled using N/S-NAC as the negative electrode, NiCo₂O₄ nanosheets as the positive electrode and 2 M KOH as electrolyte solution. This supercapacitor showed good electrochemical performance with specific capacitance of 49.3 F g^-1 at 1 A g^-1 and high energy density of 15.4 Wh kg^-1 at a power density of 749.2 W kg^-1. Practical experiment exhibited that one ASC can lighten a LED for about five minutes.