A novel Co₉S₈–MoS₂ nanosheet arrays@HCSs with superior capacitive and cycling performance for hybrid supercapacitor

Due to high conductivity and electrochemical activity, transition metal sulfides and their complexes have emerged as attractive electrode materials for supercapacitors. Herein, heterostructures of Co₉S₈–MoS₂ nanosheet arrays on the hollow carbon spheres (HCSs) with yolk-shell structure (Co₉S₈–MoS₂ NSAs@HCSs) are synthesized by a hydrothermal method and in-situ sulfurization of silicates. This core-shell structure can effectively improve the conductivity and reaction kinetics, resulting in a notable improvement in the cycling and capacity properties. The Co₉S₈–MoS₂ NSA@HCSs electrode has an outstanding cycle stability (96.9 %) after 10, 000 cycles at 10 A g⁻¹ and a high specific capacity of 804C g⁻¹ at 1 A g⁻¹. The effects of solution concentration and sulfurization time on the microstructures and electrochemical properties of the electrode are also investigated. Furthermore, the hybrid supercapacitor (HSC) is assembled with Co₉S₈–MoS₂ NSA@HCSs (positive electrode) and HCSs (negative electrode). Additionally, the HSC delivers 98.2 % of cycling stability after 10, 000 cycles at 10 A g⁻¹. The energy density of 45.6 Wh kg⁻¹ can be obtained at the power density of 770.4 W kg⁻¹.