Anion-exchange reaction synthesized CoNi2S4 nanowires for superior electrochemical performances

Abstract

In this paper, we report CoNi₂S₄ nanowire arrays (NWAs) on 3D nickel foams based on an anion-exchange reaction which involved the pseudo Kirkendall effect. Due to the low electronegativity of sulfur, CoNi₂S₄ NWAs exhibit higher conductivity compared with Ni–Co oxide NWAs when used as active materials in supercapacitors. The electrochemistry tests show that these self-supported electrodes are able to deliver ultrahigh specific capacitance (1250 F g⁻¹ at a current density of 5 mA cm⁻²), together with a considerable areal capacitance (2.5 F cm⁻² at a current density of 5 mA cm⁻²), Furthermore, a capacitance retention of 72% after 5000 charge–discharge cycles at 5 mA cm⁻² is obtained, indicating the excellent cycling stability of the CoNi₂S₄ NWA/nickel foam electrode. The superior electrochemistry capacity demonstrates that CoNi₂S₄ NWAs are promising electrode materials for supercapacitor applications.