A study on the effect of phase conversion of tungsten nanostructures on their electrochemical energy storage performance

Abstract

Herein, we report the synthesis of tungsten based nanostructures such as WO3, WO3−x (W02.72:WS2), and WS2 through a facile single step hydrothermal technique. The optical, structural, and morphological studies are conducted, and the electrochemical performance of each electrode material is evaluated in a symmetric two electrode configuration. An enhancement in the electrochemical energy storage performance has been observed on changing the phase from WO3 to WS2, which may be due to the accompanying changes in morphology and surface area. At 1 A g−1, the symmetric supercapacitors with WO3, WO3−x, and WS2 electrodes exhibit specific capacitance values of 62, 86, and 215 F g−1, respectively. At a power density of 0.76 kW kg−1, the WO3, WO3−x and WS2 based devices offer energy density values of 5.5, 7.6, and 19.1 W h kg−1, respectively. The WS2 electrode based supercapacitor retains an excellent cycling stability rate of 97% over 10 000 continuous charge discharge cycles.