Comparison of different polysaccharides as carbon source for super capacitor electrodes

The Philippine is one of the world's largest producers of carrageenan, a sulfated polysaccharide extracted from indigenous seaweed varieties. Aside from its traditional food and dairy uses, carrageenan may be a source of carbon for high performance super capacitor. A super capacitor is an energy storage device similar to batteries. It is also known as electrochemical double layer capacitor (EDLC). The charge is stored in the electrochemical double layer at the electrode-electrolyte interface. High capacitance is achieved because of the high surface area of the carbon material that is typically used. In this study, carbonized materials from kappa-and iota-carrageenan were compared with other polysaccharide such as sodium alginate and chitosan. Carbonization was done by pyrolysis of the polysaccharide under flowing nitrogen at 600 degree centigrade for 3 hours. The carbonized materials were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, BET surface area analysis and cyclic voltammetry. The carbonization yields for the different polysaccharide range from 36 to 72% with no particular trend with respect to type of polysaccharide. The FTR spectra show the expected polar functionalities typical of activated carbon which show vibration frequencies of C=O at 1650 cm-1 and C-O stretching around 1000-1200 cm-1. The CV measurements using the carbonized material as working electrode ar different cycling rates between -200 mV to 500 mV relative to Ag/AgC1 reference electrode show capacitive behavior for the carbon derived from the carrageenans. (author)