Temperature effect on the binder-free nickel copper oxide nanowires with superior supercapacitor performance

Abstract

Although the use of nickel oxide in supercapacitor electrodes has been reported extensively, the effect of incorporating copper in the binary compound is not known. Arrays of nickel copper oxide nanowires on the current collector via a simple and industrially compatible route have been successfully synthesized. A systematic study on the effect of temperature is also presented. Strikingly, through conductivity modification and binder-free growth, the as-grown nanowires show high specific capacitance (2.24 F cm² at 10 mA; 1955 F g⁻¹ at 1 mV s⁻¹), good rate capability (still 2.18 F cm² at 50 mA, 1542 F g⁻¹ at 50 mV s⁻¹), and excellent cycle life (90% after 1000 cycles at a high charging–discharging rate 10 A g⁻¹). An asymmetric full cell is then prepared and tested, and very high energy density (30 Wh kg⁻¹) is achieved. Ideal capacitive behavior (rectangular shape of cyclic voltammetry) is shown with this tailored architecture of the full cell.