A hybrid of MnO₂ nanowires and MWCNTs as cathode of excellent rate capability for supercapacitors

A hybrid of MnO₂-nanowires and MWCNTs to be used as cathode in a supercapacitor with good electrochemical performance was prepared by a facile hydrothermal method. In this hybrid the α-MnO₂ nanowires are well entangled with MWCNTs. The MWCNTs provide a network for fast electron transport whereas MnO₂ nanowires show a fast redox response. Since gain/loss of both electrons and ions can be realized very rapidly at the same time, the hybrid has an excellent rate capability and delivers an energy density of 17.8 Wh kg^-1 at 400 W kg^-1, which is maintained almost constant even at 3340 W kg^-1 in 0.5 M Li₂SO₄ aqueous electrolyte. The cycling behavior is very good even in the presence of oxygen. The data present great promise for the hybrid as a practical cathode material for aqueous supercapacitor.