Cellulose-derived nitrogen-doped hierarchically porous carbon for high-performance supercapacitors

Heteroatom-doped porous carbon materials are one of the most promising electrodes for high-performance supercapacitors. However, the development of a simple, green and low-cost strategy for their preparation is still highly challenging. In this study, we reported a simple and sustainable preparation of nitrogen-doped hierarchically porous carbon (NHPC) by using cellulose as raw materials. A NaOH/urea (7:12) system acted as the solvent, activator, and dopant simultaneously. The resultant NHPC has a high BET specific surface area of 2245 m 2 g −1 , a typically porous architecture comprising of micro-, meso-, and macropores with an appropriate average pore size of 2.83 nm, as well as a suitable nitrogen-doping degree of 3 wt%. The unique features of NHPC afford an outstanding specific capacitance of 300 F g −1 at 0.5 A g −1 , representing a new capacitive record among the cellulose-derived carbon electrodes reported so far. The NHPC//NHPC supercapacitor cell displays a high energy density of 17.2 Wh kg −1 at 452 W kg −1 , and maintains 12.1 Wh kg −1 at 4500 W kg −1 . High rate capability (81% of capacitance retention from 0.5 to 10 A g −1 ) and excellent cycling stability (5% loss after 10,000 cycles) have been also demonstrated. The facile and affordable synthesis route together with outstanding energy storage behavior endows the cellulose-derived NHPC with promising application for supercapacitors. Graphical abstract