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, WO_3−x (W0_2.72: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, WO_3−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, WO_3−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.