Nori-based N, O, S, Cl co-doped carbon materials by chemical activation of ZnCl2 for supercapacitor

Abstract

Plant biomass has gained much attention as raw materials for preparing porous carbon materials used in supercapacitors. In this paper, nori-based N, O, S, Cl co-doped carbon materials are prepared by a method of direct ZnCl2 activation in high carbon yields over 30%. The prepared carbons are systematically characterized by N2 adsorption/desorption, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, infrared spectroscopy and X-ray photoelectron spectroscopy. The electrochemical capacitive performances are investigated in 6 M KOH electrolyte. Although the prepared carbons possess relative undeveloped porosity with low specific surface area and small pore volume, the nori-based carbons exhibit good capacitive performance due to the combined contributions of electrochemical double layer and pseudo-capacitance. The nori:ZnCl2-2:1 carbons show a high capacitive performance of 220 F g−1, good rate capability (61.5% in the range of 0.1–10 A g−1), and good long-term cycle stability (96.6% after 5000 cylces). More importantly, the Nori:ZnCl2-2:1-800 exhibits a very high specific volumetric capacitance of up to 307.7 F cm−3. This work shows that direct ZnCl2-activated seaweed carbon materials are promising electrode materials for supercapacitor applications.