Viologen-assisted manganese oxide electrode for improved electrochemical supercapacitors

Di-(3-diaminopropyl)-viologen (DAPV) was used as a foreign molecule within electrolyte during electrodeposition of MnO2 (MnO2–V) for the first time, wherein, higher oxygen evolution rate induced by DAPV showed increase in surface roughness and porosity. The MnO2–V electrode showed a specific capacitance, SC of 229 F/g which was about five times higher than MnO2 without DAPV, MnO2–N (48 F/g) at the scan rate of 10 mV/s. In presence of DAPV, at the MnO2/current collector interface, lower contact resistance was obtained from electrochemical impedance spectroscopy measurement. Finally, diminished electrical conduction and interference of ion diffusion caused by residual MnO2 resulted in decrease of SC with an addition of deposition charges. Sustainable stability for electrochemical supercapacitor electrode was observed in MnO2–V by investigating subsequent charge–discharge cycling.