Amorphous CoSx nanoparticles anchoring onto N-doped carbon nanotubes as high-performance electrodes for hybrid supercapacitors

Abstract

Cobalt sulfide has been considered as one kind of promising battery-type electrode material (BTEM) for hybrid supercapacitors (HSCs). However, unsatisfactory rate capability and cyclic stability still hinder its further practical application in high-performance HSCs. Here, amorphous CoSx nanoparticles are anchored onto N-doped carbon nanotubes (N-CNTs) to form CoSx/N-CNTs nanocomposites by a chemical bath deposition (CBD) and subsequent sulfurization reaction. Originating from the synergistic effect of amorphous CoSx nanoparticles and flexible N-CNTs conductive backbones in the nanocomposites, the prepared CoSx/N-CNTs nanocomposites exhibit enhanced specific capacities (899 C g−1 at 3 A g−1 and 611 C g−1 at 20 A g−1) and long-term cyclic stability (initial capacity retention of 94% after 5000 cycles at 10 A g−1) compared with CoSx and N-CNTs electrodes. In addition, a HSC device is fabricated using CoSx/N-CNTs and N-CNTs as the positive and negative electrodes, respectively, which can deliver an energy density of 51.9 Wh kg−1 at a power density of 800 W kg−1. Therefore, the constructed CoSx/N-CNTs nanocomposites hold promise for designing high-performance cobalt sulfide-based electrode materials for further practical application in HSCs.