Boosting capacitance and energy density by construction NiCoO2/CoS2 nanocomposites arrays as pseudocapacitor

Abstract

Supercapacitors have attracted extensive attention because of their ultrahigh power density and huge potential for applications in pulsed power devices. Metal oxides and hydroxides are believed to be promising electrodes for supercapacitors. However, their poor electron/ion transport rate prevent them from achieving satisfactory rate performance. Herein, NiCoO2 nanowires and NiCoO2 nanoflakes covered with CoS2 were in-situ formed on a gold-coated nickel foam. The layered structure facilitates the rapid transmission of electrolyte and improves the mechanical stability of the electrodes. Meanwhile, the introduction of gold layer obviously improves the conductivity and electron/ion transmission. Accordingly, the electrode based on NiCoO2 nanowires/CoS2 nanocomposite exhibits an ultrahigh specific capacitance of 3.28 F cm−2 (2186.7 F g−1) at 2 mA cm−2 and retains 90.4% of the initial capacitance after 4000 cycles. Furthermore, the assembled hybrid supercapacitor device shows a high energy density of 43.48 W h kg−1 at a power density of 142.3 W kg−1. The superior energy storage performances make these layer-structured NiCoO2/CoS2 nanocomposites promising candidates for high performances supercapacitors.