New Methods for the Fabrication of Composites for Supercapacitor Electrodes with High Active Mass Loading

MnO2-multiwalled carbon nanotube (MWCNT) supercapacitor electrodes with active mass loading of 30-45 mg cm-2 were prepared. In method 1, MnO2 and MWCNT were dispersed using 3,4-dihydroxybenzaldehyde (DHB) and toluidine blue (TD), respectively. The Schiff base formation between amino group of TD and aldehyde group of DHB facilitated improved mixing of MnO2 and MWCNT. In method 2, gallocyanine (GC) was used as a co-dispersant for MnO2 and MWCNT. The catecholate type bonding of DHB and GC allowed for adsorption of the dispersant molecules on MnO2 nanoparticles. The electrodes, prepared by method 1 showed higher capacitance, compared to the electrode, prepared by method 2. The highest capacitance of 7.8 F cm-2 (173 F g-1, 139 F cm-3) was obtained at a scan rate of 2 mV s-1 and active mass loading of 45 mg cm-2.