Performance of carbon nanosheet electrode from aquatic wood waste in supercapacitor

Abstract

Disposal of conventional polymer-based electrodes and capacitor can cause pollutions or incur high cost. More carbon based nanosheet electrode is more environmental friendly. Novel supercapacitors were fabricated using carbon nanosheet electrode. Two pieces of thick layer carbon nanosheet electrodes were used as the cathode; the anode were made of carbon nanosheet and graphite mixture with a ratio of 7: 3, 10 % binder and coated on top of a glass surface. The polymer gel electrolytes containing barium carbonate (BaCO3) or calcium carbionate (CaCO3) were filled in the middle of the electrodes to act as a supercapacitor. The concentrations of electrolytes, BaCO3 and CaCO3 were 10 %; 20 %; 30 %. The performance of the supercapacitors was determined by cyclic voltammetry, and charge-discharge galvanostatic methods performed using a potentiostat. The decreasing in capacitances occurred along with the increase of scan rate, from 5 mV s-1 to 100 mV s-1. There is only a slight decrease in the first cycle, as shown by the increased slope of 20 % CaCO3 of supercapacitor. The first cycle plot shows the existence of linearity both in the direction of charging and discharging. All supercapacitors have the same slope value indicating the same rate for both charging and discharging process. Except for the supercapacitor with 20 % CaCO3 where different slope values were observed for its charging and discharging rate, i.e., 1.345 and -1.344. The result showed that the supercapacitor has a charging rate faster than its discharging rate. The cyclic voltammetry tests showed that the highest value of 6.95 mF g-1 was achieved using the supercapacitor of 10 % CaCO3 as electrolyte; or 3.91 mF g-1 with 10 % BaCO3. A novel supercapacitor, using carbon nanosheets derived from aquatic wood waste as eletrodes and polymer-based gel as electrolytes, was developed.