Engineering a vanadium-incorporated MoS2-based mixed metal dichalcogenide system for improved supercapacitor performance

Abstract

In this study, we developed a mixed metal dichalcogenide system of molybdenum‑vanadium disulfide with the chemical formula Mo1-xVxS2, where x = 0.3, 0.5, and 0.7, corresponding to Mo:V ratios of 70:30, 50:50, and 30:70 using a facile one-pot hydrothermal method. This mixed metal structure is expected to influence both the basal plane and the edge plane towards engineering the active sites in the resulting system forming xMon+-yV4+-zS2− network, which is a crucial for its improved electrochemical performance. Structural studies confirmed the emergence of structural distortion in the system due to the difference in the ionic sizes of Mo and V ions, leading to strain in the lattices. Furthermore, electron microscopic analysis revealed the formation of aggregated nano-petals for bare MoS2, while these petals self-assembled to form flower-like microspheres upon the introduction of V in the mixed metal (Mo1-xVxS2) systems. Consequently, the Mo0.5V0.5S2 delivered a specific capacitance of 492.2 F g−1 at 1 A g−1 with substantial capacitance retention of 94 % up to 3000 cycles, which is twofold higher compared to bare MoS2. Moreover, the fabricated symmetric device achieved an energy density of 19.5 Wh kg−1 and a maximum power density of 9000 W kg−1 with capacitance retention of 92.8 and 86.3 % after 5000 and 10,000 charge/discharge cycles, respectively.