Potentiodynamically deposited nanostructured manganese dioxide as electrode material for electrochemical redox supercapacitors

Amorphous nanostructured hydrated electrochemical manganese dioxide (EMD) was potentiodynamically deposited on stainless steel (SS). Electrolyte medium used for the deposition was 0.5 M H2SO4 + 0.5 M MnSO4·5H2O. The scan rate of deposition was varied between 50 and 200 mV s−1. The EMD deposited SS electrodes were characterized by cyclic voltammetry (CV) in 0.1 M Na2SO4 for electrochemical redox supercapacitors. The specific capacitance (SC) of EMD increases by increasing the scan rate of deposition. For EMD deposited at 200 mV s−1, a maximum SC of 482 F g−1 was obtained from cyclic voltammetry at a scan rate of 10 mV s−1. For the same electrode, a SC value of 275 F g−1 was obtained even at a high scan rate of 150 mV s−1, indicating high power characteristics of the material. The SC was found to increase with the increase in thickness of EMD. Long cycle-life and stability of EMD were also demonstrated.