Facile synthesis of cobalt manganese oxides nanowires on nickel foam with superior electrochemical performance

Abstract

Cobalt and manganese oxides ((Co, Mn)3O4) nanowires freely standing on nickel foam are prepared by a simple template-free growth process and heat treatment. The results show that the (Co, Mn)3O4 composite forms a uniform film and densely covers the nickel foam substrate. The film is composed of nanowires with a diameter up to around 30–40 nm. The electrochemical capacitance behavior of the self-supported binderless nanowires electrode is investigated by cyclic voltammetry, galvanostatic charge/discharge test and electrochemical impedance spectroscopy. The (Co, Mn)3O4/Ni-foam electrode exhibits a high specific capacitance of 611 F g−1 at a charge/discharge current density of 2.38 A g−1 in 6.0 mol dm−3 KOH electrolyte. Furthermore, the (Co, Mn)3O4/Ni-foam electrode delivers a high energy density 13.6 Wh kg−1, and even a high power density of 5.68 kW kg−1. More importantly, the specific capacitance retention is 95% after 2000 charge/discharge cycles at 2.38 A g−1 and with columbic efficiency higher than 98%. This work suggests that the as-prepared (Co, Mn)3O4/Ni-foam electrode has potential application in electrochemical capacitors.