Synthesis of 3D flower-like cobalt sulfide hierachitecture for high-performance electrochemical energy storage

In this work, rationally designed 3D cobalt sulfide nanoflowers (3D CoS NF) were prepared by a facile one-step solvothermal method. The 3D CoS NFs were assembled from low dimensional building blocks with thin 2D nanoflakes with an average thickness of 19 nm (between 1 and 100 nm). SEM and TEM images revealed that the flower-like hierarchitecture consisted with an average diameter of 12 μm. XRD data indicated that the as-prepared sample had a pure hexagonal CoS crystal structure. Such 3D CoS NF was applied for fast-charge storage device which delivered a specific capacity of 669 C g⁻¹ at a current density of 1 A g⁻¹. By assembling the 3D CoS NF into an asymmetric supercapacitor (ASC), the device showed 129.0 C g⁻¹ capacity and long cycle stability (85.7% retention after 3000 cycles).