Tailoring the interfacial surfaces of tungsten and molybdenum tungsten disulfide electrodes for hybrid supercapacitors

Abstract

The layered structures of tungsten disulfide (WS₂) and molybdenum tungsten disulfide (MoWS₂) are considered as the most promising electrode materials for energy storage devices. Herein, MS (magnetron sputtering) is required for the deposition of WS₂ and MoWS₂ on the surface of the current collector to attain an optimized layer thickness. The structural morphology and topological behavior of the sputtered material were examined via X-ray diffraction and atomic force microscopy. Three-electrode assembly was used to start the electrochemical investigations to identify the most optimal and effective sample among WS₂ and MoWS₂. CV (cyclic voltammetry), GCD (galvanostatic charging discharging), and EIS (electro-impedance spectroscopy) techniques were employed to analyze the samples. After preparing WS₂ with optimized thickness as the superior performing sample, a hybrid device was designed as WS₂//AC (activated carbon). With a remarkable cyclic stability of 97% after 3000 continuous cycles, the hybrid supercapacitor generated a maximum energy density (E_s) value of 42.5 W h kg⁻¹ and 4250 W kg⁻¹ of power density (P_s). Besides, the capacitive and diffusive contribution during the charge–discharge process and b-values were calculated by Dunn's model, which lay in the 0.5–1.0 range and the fabricated WS₂ hybrid device was found to have a hybrid nature. The outstanding outcomes of WS₂//AC make it suitable for future energy storage applications.