Preparation and Electrochemical Properties of Multiscale Porous Active Carbon for Supercapacitor Electrodes Made from Ultra-Pure Lignite by Microwave Irradiation

摘要

Multiscale porous activate carbon with appropriate pore-size distribution for supercapacitor electrodewas prepared from ultra-pure lignite with only 0.3wt% ash through the synergistic effect of microwaveirradiation, the activation of KOH and ZnCl2, ultra-fine grinding and surface modification with sodiumdodecyl benzene sulfonate(SDBS) on active carbon. The active carbon sample was characterized usinglaser particle size analyzer and specific surface area and pore size analyzer. Electrochemical propertiesof active carbon were investigated using cyclic voltammogram(CV), electrochemical impedancespectroscopy(EIS) and galvanostatic charge-discharge test with the electrolyte of 6M KOH solution..The results show that the active carbon obtained at the conditions of microwave irradiation power of700W, microwave irradiation time of 6minutes and weight ratio of 1:2:3(Lignite/ZnCl2/KOH ) has2 -1 high specific surface area(1536m g ) and large percentage of micropores (59.05%). When the activecarbon is ultra-fine grinded to an average size of 2.1m, the specific surface area will be improved to2 -1 1696m .g . Active carbon treated with ultra-fine grinded and surface modification using SDBS-1 presents a high specific capacitance of 189Fg and good cycle stability in KOH electrolytes.