Mn3O4 and (ZnFe)OOH Composites for Supercapacitors with High Active Mass

A new colloidal method has been developed for the fabrication of Mn3O4-carbon nanotube (CNT) composites for positive electrodes of supercapacitors and areal capacitance of 5.04 F cm−2 has been achieved. In this method, chemical precipitation of Mn3O4 was performed in the presence of carbon nanotubes, dispersed using a tolonium chloride dye. An electrostatic heterocoagulation mechanism has been developed, which allowed for enhanced mixing of Mn3O4 and CNT, and resulted in enhanced electrochemical performance at high active mass of 36 mg cm−2. Testing results revealed changes in microstructure and oxidation state of Mn during cycling, which allowed for enhanced capacitance. In order to utilize the high capacitance of the positive Mn3O4-CNT electrodes in supercapacitor devices, advanced negative electrodes have been developed. (ZnFe)OOH-polypyrrole coated CNT electrodes with enhanced areal capacitance in a negative potential window have been fabricated. Asymmetric devices showed promising performance in a voltage window of 1.6 V.