Achieving the high-energy-density asymmetric supercapacitor by hierarchical molybdenum-vanadium-sulphide@covalt sulphide core–shell nanoporous hybrid as cathode and iron oxide@carbon-nanofibers/nitrogen-doped reduced graphene oxide aerogel as anode

In recent decades, supercapacitors have attracted much research as low-cost, reliable, and environment-friendly energy storage devices. However, the low energy density and low operating voltage limit its wide applications. Herein, a novel 1D–2D constructed 3D multicomponent Mo_x:V_y–S@Co₉S₈ core–shell nanowires array is designed and fabricated as the cathode material through a simple and economical two-step hydrothermal reaction and electrodeposition process. The constructed 3D Mo_0.5V_0.5–S@Co₉S₈ electrode exhibits excellent charge storage capability; an area capacity of 0.91 mA h cm⁻² with a corresponding specific capacity of 480.9 mA h g⁻¹ at 2 mA cm⁻². Moreover, a solid-state ASC (SS–ASC) is assembled with the as-obtained Fe₂O₃@CNFs/N–rGO aerogel as the anode, the constructed 3D Mo_x:V_y–S@Co₉S₈ NWAs as cathode, and KOH–PVA–gel as a gel electrolyte. As proof of concept, the assembled SS–ASC display an excellent operating voltage window of ~1.7 V and an outstanding energy density of ~108.47 W h kg⁻¹ at ~520.65 W kg⁻¹ power density. Also, when connected in series, the two SS–ASC devices can run an electronic clock for 30 min, demonstrating the practicability of the constructed 3D Mo_x:V_y–S@Co₉S₈ NWAs as a promising electrode material for the development of the high energy density ASC.