Electrochemical performance of hybrid supercapacitor device based on birnessite-type manganese oxide decorated on uncapped carbon nanotubes and porous activated carbon nanostructures

Abstract

Birnessite-type MnO2 synthesized on the surface of carbon nanotubes (CNTs) via facile hydrothermal reflux technique to produce MnO2-CNT nanocomposite and 3D microporous nanostructured activated carbon (AC) derived from cork (Quercus Suber) with good microstructural, morphological and electrochemical properties are herein reported. A hybrid supercapacitor device comprising of MnO2-CNT nanocomposite as positive electrode and AC as the negative electrode was successfully fabricated and tested for energy storage application. The device displayed a maximum working potential of up to 2 V due to the excellent synergistic contribution from the MnO2-CNT nanocomposite and AC material derived from cork (Quercus Suber). The fabricated device displayed good electrochemical performance having an energy density of ∼25 Wh Kg−1 that corresponds to a power density of 500 W Kg−1 at a current density of 0.5 A g−1 in a 1 M Li2SO4 aqueous neutral electrolyte. The device exhibited an excellent stability of ∼100% coulombic efficiency after 10,000 charge-discharge cycles and excellent capacitance retention after potentiostatic floating test for 60 h.