High-Energy-Density Quasi-Solid-State Supercapacitor with a MoS2@FeS2 Core–Shell Heterostructure as an Advance Electrode Material

Metal chalcogenides with heterostructures exhibit fascinating structures and properties, enabling them to be used in various applications. In this work, we developed a core–shell heterostructure of MoS2@FeS2 via a two-step hydrothermal and solvothermal method and explored its electrochemical performance in a quasi-solid-state symmetric and asymmetric supercapacitor. This unique heterostructure comprises MoS2 nanoflakes decorated over octahedron-like FeS2, which enhances the electron/ion mobility and provides more number redox sites to boost the electrochemical performance. The symmetric configuration exhibits a maximum specific capacitance of ∼386 F/g at a current density of 1 A/g, with an excellent capacitance retention of ∼90.3% over continuous 10 000 charge/discharge cycles at 10 A/g. Further, the heterostructure shows a high energy density of ∼53 Wh/kg at a power density of ∼699 W/kg. At the same time, the asymmetric configuration delivers a maximum capacitance of ∼186 F/g with energy and power density values of ∼29 Wh/kg and ∼900 W/kg, respectively. Two asymmetric cells connected in series can illuminate red and blue LEDs, conforming to their practical application. It is believed that the MoS2@FeS2 core–shell heterostructure can be a promising electrode material for supercapacitor application.