In-situ Fabrication of Alternately Stacked MoS2/Au Multilayered Thin-Film Electrodes for Electrochemical Energy Storage Application

Abstract

Molybdenum disulfide (MoS2) is considered as one of the most researched transition metal dichalcogenides in several energy harvesting and storage applications. Particularly, the layered structure of MoS2 allows the intercalation and de-intercalation of ions through it, giving rise to its pseudocapacitive behavior which makes it a promising electrode material for electrochemical supercapacitors. In this work, we have synthesized alternately stacked MoS2–Au–MoS2 multilayered thin-film electrodes on stainless steel current collectors (1 × 1 cm2) using DC magnetron sputtering technique. Electrochemical performance was evaluated by cyclic voltammetry, charge–discharge characteristics, and electrochemical impedance spectroscopy in neutral 1 M Na2SO4 aqueous electrolyte using CHI workstation in 3 electrode configuration. The areal capacitance of bare MoS2 and MoS2–Au–MoS2 multilayered electrodes was found to be 198 and 246 mF/cm2 respectively, as calculated from the voltammetry graphs at the scan rate of 5 mV/s at similar mass loadings. Moreover, the multilayered electrodes displayed excellent cyclic retention capacities of 97.6% in comparison to single-layer MoS2 whose capacity faded to 71% after 1500 cycles. This excellent structural stability response may be credited to the presence of sandwiched thin Au layer which provides an opportunity of epitaxial growth of thin films, subsequently minimizing uncompensated thermal and lattice stress.