Optimized manganese oxide nanosheet/manganese oxide thin film/ multiwalled carbon nanotubes as hybrid electrode materials for supercapacitors

Abstract

Manganese oxide nanosheet/manganese oxide thin film/multiwalled carbon nanotubes(s-MnOx/f-MnOx/MWNTs) were used as hybrid electrode materials for supercapacitor application. Supercapacitor performance based on these hybrid materials was optimized by varying morphologies of s-MnOx. Firstly, a MWNT paste was coated onto nickel (Ni) foam and subsequently f-MnOx was deposited onto the pre-coated MWNTs/Ni foam by galvanostatic (GS) mode of electrodeposition technique at a constant current of 1 mA/cm2 using 0.1 M KMnO4 as a precursor with a fix deposited time of 5 min. Finally, s-MnOx was deposited onto the prepared f-MnOx/MWNTs/Ni foam by GS mode of electrodeposition technique at a constant current of 1 mA/cm2 using 0.1 M KMnO4 as precursor with different deposited times of 10, 15 and 20 min. Each hybrid s-MnOx/f-MnOx/MWNTs electrode was characterized by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The s-MnOx/f-MnOx/MWNTs electrode prepared by 15-min-deposited s-MnOx shows the highest specific capacitance. The capacitance improvement is attributed to the increase of electrode surface area.