Designing an asymmetric device based on graphene wrapped yolk–double shell NiGa2S4 hollow microspheres and graphene wrapped FeS2–FeSe2 core–shell cratered spheres with outstanding energy density

Abstract

Herein, we present a new method to construct a graphene wrapped yolk–double shell NiGa₂S₄ hollow microsphere (GW@YDSNGSHM) as a cathode electrode and a graphene wrapped FeS₂–FeSe₂ core–shell cratered sphere (GW-FeS₂–FeSe₂-CSS) as an anode electrode to enhance the performance of asymmetric supercapacitors. The GW@YDSNGSHM electrode shows considerable improvement of electrochemical performance including small internal resistance, reversibility, rapid kinetics, exceptional durability, and a notable specific capacitance (SC) of 2868.4 F g⁻¹. The advancement in the performance of the GW-FeS₂–FeSe₂-CSS includes a good SC of 634.6 F g⁻¹ and preferable durability. An asymmetric supercapacitor composed of the GW@YDSNGSHM (cathode) and GW-FeS₂–FeSe₂-CSS (anode) was assembled and tested. The advanced device revealed a SC of 352.30 F g⁻¹ and an energy density (ED) of 158.53 W h kg⁻¹ at a power density (PD) of 2236.16 W kg⁻¹. This improved performance is related to the structural properties of both electrodes which can ensure promising potential for future generations of electronic devices.