Nitrogen- and Sulfur-Doped Carbon Obtained from Direct Hydrothermal Carbonization of Cellulose and Ammonium Sulfate for Supercapacitor Applications

Achieving heteroatom-doped carbon materials using inorganic matter as the doping source is one of the major challenges for renewable energy storage materials. In this letter, a direct simple and reproducible methodology was designed for the preparation of nitrogen- and sulfur-doped materials by direct hydrothermal carbonization (300 °C for 1 h) of cellulose and ammonium sulfate at a mass ratio of 1:1. This N- and S-doped carbon exhibited an excellent electrochemical performance including high specific capacitance (227.3 F/g) when the current density is 1 A/g; however, its specific capacitance still retained 76.55% from the original when the current density was increased to 20 A/g,.