Porous manganese dioxide film built from arborization-like nanoclusters and its superior electrochemical supercapacitance with attractive cyclic stability

To achieve superior specific capacitance with sound cyclic stability, porous manganese dioxide (MnO2) film built from arborization-like nanoclusters is deposited for the first time on multi-walled carbon nanotube (MWCNT) pre-covered onto Pt sheet by using a unipolar pulse electro-deposition method. The obtained composite electrode MnO2 /MWCNT displays unique nanostructure and good stability. It displays specific mass capacitance as high as 553.0 F/g in 0.50 M Na2SO4 solution. The attractive capacitance performance may contribute from the synergetic effects of chemical adsorption-desorption on the spherical surface and internal intercalation/deintercalation between electrolyte ions and active material MnO2. After 2000 charge/discharge cycles at the current density of 5.0 A/g, it can retain more than 97% of the initial specific capacitance. The superior cyclic stability may depend on the well crystallized MnO2 containing more bond Mn-O-Mn but less bond Mn-O-H. In case of its counterpart MnO2/MWCNT-PM prepared using potentiostatic method, its low capacitance performance can be ascribed to the simply chemical adsorption-desorption on its flat surface between electrolyte ions and active MnO2. It can only retain about 62% of the first cycle capacitance after the charge/discharge cycles. The poor cyclic stability mainly depends on the lowly crystallized MnO2 containing more bond Mn-O-H but less bond Mn-O-Mn. (C) 2018 Elsevier Ltd. All rights reserved.