Electrochemical characteristics of two-dimensional nano-structured MnO2 for symmetric supercapacitor

Manganese oxide (MnO2) powders with various nano structures were prepared using MnSO4 as a precursor through hydrothermal method. Manganese oxides with needles, rods and flakes structure were formed depending on oxidizer used. The flakes-shaped MnO2 exhibited the higher capacitance values than other structures, both in aqueous and organic electrolytes. The charge storage mechanism observed in aqueous electrolyte is mixed type of charge insertion–extraction and surface adsorption mechanism while that in organic electrolyte is insertion–extraction. The higher specific capacitance of 342 F g−1 in NaOH, 429 F g−1 in LiClO4 and 455 F g−1 in LiPF6 was observed for the flakes-shaped MnO2 electrode.