NiCo2S4@N-CNT composites with multidimensional
hierarchical structures are rationally designed and synthesized by
a simple two-step hydrothermal strategy, aiming to achieve excellent
electrochemical performances for supercapacitor applications. The
hollow spherical NiCo2S4 nanoparticles with
both zero- and two-dimensional architecture are interconnected by
the conductive bridges of nitrogen-doped carbon nanotubes (N-CNTs,
1D). This unique structure can provide a much rougher surface, rich
two-phase interface, and porous channels exposed to electrolytes with
fast ion diffusions and electron transmissions, as well as effectively
relieve the expansion/contractions during charging and discharging.
As such, the asymmetric all-solid-state supercapacitor device assembled
by NiCo2S4@N-CNTs and activated carbons can
provide an energy density high up to 59.37 W h kg–1 at the power density (750 W kg–1). Even if the
power density is increased up to 1.5 kW kg–1, it
still can achieve the energy density superior to 45.6 W h kg–1. These results can provide the open interesting perspective to design
the favorable structure of bimetallic sulfides for supercapacitor
applications.