Application of water lettuce (Pistia S.) as conductive carbon in electrochemical capacitor

Abstract

A conductive carbon material from Water Lettuce (Pistia S.) powder has been prepared for use in Electrochemical Capacitor (EC) device. The features on surface functionality, morphology, and crystallography were analysed based on Boehm titration / FTIR, SEM and XRD instrumentations. The performance of ECs was studied by using impedance spectroscopy method,in which capacitances were calculated from the data. The surface features measurement showed that surface area (S), volume (Vm), and total volume (Vt) were 1238 m2 g-1, 5.98 cm2 g-1 and 1.99 cm3 g-1. FTIR spectrogram shows the functionality on the surface of carbon, -OH (3,800 – 4,000 cm-1), C-C, C-O, C-N (500 – 1,500 cm-1) and C=C, C=O, C=N (1,050, 1,500, 2,300 – 2,400 cm-1). XRD analysis showed that carbon sample has sharp peaks indicating crystallite of carbon and sylvite. SEM analyses indicated the existence of micro pores in the carbon samples. The higher impedances were come from electrodes with high content (70 %) of WL carbon, range from 100 to 120 ohm. Low content carbon (30 %) electrode has impedance range from 80 to 100 ohm. Critical point to capacitance – resistance character of EC for the asymmetric and symmetric ECs was 5 and 114 Hz. Capacitance analysis plots of ECs showed convergence of the values and reached minimum in frequency near 500 Hz. The maximum value of capacitance is about 0.401 F.