Molten salt synthesis of nitrogen and oxygen enriched hierarchically porous carbons derived from biomass via rapid microwave carbonization for high voltage supercapacitors

By Cheng, Yinfeng; Li, Baoqiang; Huang, Yanjuan; Wang, Yaming; Chen, Junchen; Wei, Daqing; Feng, Yujie; Jia, Dechang; Zhou, Yu
Published in Applied Surface Science 2018

Abstract

Nitrogen and oxygen enriched hierarchically porous carbons (NOHPCs) derived from biomass have been successfully prepared by rapid microwave carbonization coupled with molten salt synthesis method in only 4 min. ZnCl2 plays important roles as microwave absorber, chemical activation agent and porogen in this process. NOHPC-1:10 sample possesses the maximum specific surface area of 1899 m2 g?1 with a pore volume of 1.16 cm3 g?1 and mesopore ratio of 70%, as well as nitrogen content of 5.30 wt% and oxygen content of 14.12 wt%. When evaluated as an electrode in a three-electrode system with 6 M KOH electrolyte, the material exhibits a high specific capacitance of 276 F g?1 at 0.2 A g?1, with a good rate capability of 90.9% retention at 10 A g?1. More importantly, the symmetric supercapacitor based on NOHPC-1:10 in 1 M Na2SO4 electrolyte exhibits a high energy density of 13.9 Wh kg?1 at a power density of 120 W kg?1 in a wide voltage window of 0

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