Manganese dioxide–carbon nanotube composite electrodes with high active mass loading for electrochemical supercapacitors

Abstract

MnO2–multiwalled carbon nanotube (MWCNT) composites were prepared for application in supercapacitor electrodes and devices. Good dispersion and mixing of the individual components were achieved using conceptually new strategies, allowing for significant improvement in the electrochemical charge storage properties. Composite C1 was prepared using chelating polyaromatic sulfasalazine molecules, which adsorbed on the individual components, allowed for their good dispersion and improved mixing by creating links between the components. Composite C2 utilized a Schiff base linkage mechanism for improved mixing between MnO2 and MWCNT. New electrochemical strategies allowed for high capacitance and good capacitance retention at high charge–discharge rates at high active mass loading, which was 30 mg cm−2. Composites C1 and C2 showed capacitances of 4.5 and 4.4 F cm−2, respectively, at a scan rate of 2 mV s−1. However, composite C2 showed a higher capacitance retention at high scan rates, which was found to be 66% at a scan rate of 100 mV s−1. The asymmetric devices, prepared using composite C2 as positive electrodes and activated carbon–carbon black negative electrodes, showed promising performance in a voltage window of 1.6 V.