Preparation of nanowire-like core–shell Ni₃Se₄@NiCo₂O₄/NF composite electrodes for high-performance supercapacitors

Double transition metal oxides and oxygen group element compounds are widely used in supercapacitor electrode materials. In this work, nanowire-like NiCo₂O₄ was synthesised using a hydrothermal method, and Ni₃Se₄ was deposited on a nickel foam using NiCo₂O₄ as the base material utilizing electrodeposition. Composites exhibit superior electrochemical properties with lower impedance values than single materials. Ni₃Se₄@NiCo₂O₄/NF composite showed an areal capacitance of 1404.17 mF cm⁻² at 1 mA cm⁻², outperforming both NiCo₂O₄/NF (735.83 mF cm⁻²) and Ni₃Se₄/NF (523.5 mF cm⁻²) electrodes. The asymmetric supercapacitor is formed by using Ni₃Se₄@NiCo₂O₄/NF composite electrode as anode and carbon electrode as cathode with 3 M KOH solution as electrolyte. The device has an energy density of 0.0864 mWh cm⁻² at a power density of 0.8 mW cm⁻² and 0.0231 mWh cm⁻² at a power density of 7.996 mW cm⁻². The capacitance retention of this asymmetric supercapacitor remained 91.76% after 5000 cycles at a current density of 10 mA cm⁻².