Experimental and theoretical insights into the supercapacitive performance of interconnected WS2 nanosheets

Abstract

Transition metal dichalcogenides (TMDs) are fascinating and prodigious considerations in the electrochemical energy storage sector because of their two dimensional chemistry as well as heterogeneous characteristics. Herein, we synthesized interconnected WS₂ nanosheets by a hydrothermal method followed by sulphuration at 850 °C in an argon atmosphere. The ultrathin WS₂ nanosheet array is endowed with an excellent specific capacitance of 74 F g⁻¹ at the current density of 3 A g⁻¹ up 7000 cycles. Moreover, a symmetric supercapacitor was fabricated using WS₂ nanosheets, which provided the admirable high specific capacity of 6.3 F g⁻¹ at 0.05 A g⁻¹ with the energy and power density of 5.6 × 10² mW h kg⁻¹ and 3.6 × 10 ⁵ mW kg⁻¹, respectively. Density functional theory (DFT) simulations revealed the presence of populated energy states near the Fermi level resulting in a high quantum capacitance value, which supports the experimentally achieved high capacitance value. The attained results recommend interconnected WS₂ nanosheets as a novel, robust, and low-cost electrode material for supercapacitor energy storage devices.