Hydrothermal synthesis of VS4/CNTs composite with petal-shape structures performing a high specific capacity in a large potential range for high-performance symmetric supercapacitors

Abstract Vanadium sulfide (VS 4 ) is recognized as a good anode material for energy storage devices because of its chain-like structure and high content of sulfur. Herein, the patronite VS 4 anchored on carbon nanocubes (denoted as VS 4 /CNTs) with a petal-shape structure consisting of nanolayers is successfully prepared through a one-step hydrothermal reaction. The influence of the optimal ratio of VS 4 and CNTs on the electrochemical properties of VS 4 /CNTs composite is studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The addition of CNTs increases the conductivity and relieves the volume expansion/contraction, resulting excellent electrochemical properties of VS 4 /CNTs. In the potential window of −1.4 V to 1.4 V, the VS 4 /CNTs composite electrode delivers an outstanding specific capacitance of 330 F g −1 (924 C g −1 ) at 1 A g −1 , which is much higher than that of VS 2 with 105 F g −1 (294 C g −1 ). The VS 4 /CNTs symmetric supercapacitor (SSC) device exhibits the areal capacitance as high as 676 mF cm −2 (1488 mC cm −2 ) at 0.5 mA cm −2 , and the energy density of 4.55 W h m −2 (51.2 W h kg −1 ) at the power density of 2.75 W m −2 (30.95 W kg −1 ) within a large voltage up to 2.2 V. All the results confirm that VS 4 /CNTs composite with petal-shape structures is a promising material for high-performance energy storage devices.