N-rich and O-poor doped carbon prepared via facile ammonium nitrate assisted hydrothermal carbonization for robust supercapacitors

N-carbon material was prepared via ammonium nitrate (AN) assisted by hydrothermal carbonization (HTC) of cellulose-derived N-carbon materials to improve the electrochemical properties of supercapacitors. The N-carbon constructed electrode possessed a high specific capacitance of 318 F/g at 1 A/g, excellent cycling stability with 98% capacitance retention after 10,000 cycles, as well as enhanced rate capability in symmetric supercapacitor. During HTC, the improved electrochemical performance was decisively determined by the uniquely designed nitrogen supply, acidic catalyst, and powerful oxidant. Moreover, improving hydrolysis of cellulose to enhance carbonization and high nitrogen doping content of the prepared N-carbon material were the key factors contributing to its improved electrochemical properties. These findings improve the understanding of how cellulose appropriately is oxidant assisted HTC to produce N-carbon for applications in high-energy-density supercapacitors.