Nanowire-assembled Co₃O₄@NiS core–shell hierarchical with enhanced electrochemical performance for asymmetric supercapacitors

In this study, a three-dimensional (3D) hierarchical Co₃O₄@NiS core–shell heterostructure supported on nickel foam (NF) has been constructed. This Co₃O₄@NiS/NF can directly serve as a binder-free electrode for a pseudocapacitor, which could achieve a high specific capacitance of 1395.3 F g⁻¹ at a current density of 1 A g⁻¹ in 6 M KOH electrolyte, and an ideal rate capability of 711 F g⁻¹ at a current density of 10 A g⁻¹. Additionally, the electrode has a high capacitance retention of 89.9% after 5000 cycles. The asymmetric supercapacitor exhibits the maximum energy density of 61.34 W h kg⁻¹ at a power density of 800 W kg⁻¹, as well as an excellent cycling life of 89.3% capacitance retention. The enhanced electrochemical performance can be mainly ascribed to the special 3D core–shell nanowire arrays nanostructure with great conductivity, enlarged surface area, abundant accessible active sites and intrinsic stability. We anticipate that the present Co₃O₄@NiS/NF could be a promising electrode material for energy storage applications. (paper)