Preparation And Supercapacitive Properties Research Of Bio-waste Activated Carbon

As a new type of energy storage devices, supercapacitors have attracted the attention of scientists and engineers in recent years, and the researches on supercapacitors are focused on the electrode material. In this paper, we have prepared the loofah based activated carbon,granatum based activated carbon and peanut shells based activated carbon, and using them as a supercapacitor electrode material, and studied its supercapacitive performance. The main contents of this paper are summarized as follows:1、Loofah-based activated carbon was prepared from loofah by KOH chemical activation under nitrogen atmosphere. The structure, phase and morphology of activated carbons are characterized by N2 adsorption, X-ray diffraction, scanning electron microscopy(SEM). Then the activated carbons were tested as the electrode material of supercapacitor and electrochemical properties are characterized by cyclic voltammetry, galvanostatic charge/discharge, and AC impedance method. The results show that the carbon samples are all the amorphous carbon, which were prepared under different activation temperatures. The specific surface area of the activated carbons increased with the increasing of the activation temperature, and LAC-700 has the largest specific surface area of 936 m2·g-1. Electrochemical tests results show that the capacitance value of the sample LAC-700 is as high as 152.89 F·g-1,and LAC-700 has superior electrochemical performance and is an ideal electrode material for supercapacitors.2、Granatum carbon(GC) as the electrode material for supercapacitors is prepared via the chemical activation with different activating agent such as ZnCl2 and KOH that are intent on improving the surface area and their electrochemical performance. The structure and electrochemical properties of GC materials are characterized by N2 adsorption/desorption measurements, scanning electron microscope(SEM), cyclic voltammetry(CV), galvanostatic charge/discharge cycling and electrochemical impedance spectroscopy(EIS). The results show that the specific surface area of the granatum based activated carbons increased obviously from 573 m2·g-1 to 1341 m2·g-1 by ZnCl2 activation and to 930 m2·g-1 by KOH treatment. Furthermore, GCZ also delivers specific capacitance of 195.1 F·g-1at the current density of 0.1 A·g-1 in 30 wt.% KOH aqueous electrolyte and low capacitance loss of 28.5%when the current density increased by 10 times.3、 Peanut shells carbon severing as the electrode material for supercapacitor is prepared via simple pyrolysis reaction with KOH agent. The Structure, phase, morphology and electrochemical properties of the activated carbons are characterized by N2 adsorption, X-raydiffraction(XRD), scanning electron microscopy(SEM), cyclic voltammetry, galvanostatic charge/discharge, and AC impedance method. The results show that the sample PSAC2-900 possesses the largest specific surface area of 1621 m2·g-1, the maximum porosity of 14.6%,the maximum average pore diameter of 2.25 nm, and exhibits the highest specific capacitance of 307.44 F·g-1 in 6 M KOH. The capacitance value at current density of 5 A·g-1 of PSAC2-900 is always higher than the other carbon samples even after 1000 cycles, only decreased by 3.8%, indicating that the sample PSAC2-900 has the best power characteristics and long charge-discharge cycle stability.