Heteroatom-doped porous carbon with tunable pore structure and high specific surface area for high performance supercapacitors

Abstract

Biomass-derived porous carbons with very high specific surface area (SSA) and heteroatom-doping are important for obtaining high performance supercapacitor. In this study, we report a simple and straightforward strategy, which involves the efficient and exothermic pyrolysis of Mg/K/Mg·K-nitrate-urea-cellulose mixture with subsequent high temperature carbonization and washing treatment, to produce N-doped porous carbon with tunable pore structure. The vigorous exothermic pyrolysis of Mg/K/Mg·K-nitrate-urea-cellulose induces the formation of large macropores. The subsequent high temperature carbonization and washing treatments remove Mg,K compounds and facilitate the creation of numerous micro and mesopores. The pore size distribution of the obtained carbon is quite dependent on the Mg·K ratio in the precursors. In this manner, the three-dimensional hierarchical porous carbon with SSA larger than 2700 m2 g−1 is obtained. The obtained porous carbon as the electrodes for supercapacitor in two-electrode measurement shows high specific capacitance (279 F g−1 at 1 A g−1 in a 6 M KOH electrolyte), excellent cycling stability (larger than 89% capacitance retention after 10,000 cycles at 2 A g−1) and good rate capability (235 F g−1 at even 30 A g−1). These results indicate that biomass cellulose-derived heteroatom-doped hierarchical porous carbon is a promising material for supercapacitor.