Hydrothermal synthesis and supercapacitor electrode of low crystallinity VOOH hollow spheres with pseudocapacitance in aqueous solution

Abstract

Vanadyl hydroxide (VOOH) may bear scientific importance and novel chemical and physical properties but they are uncommonly reported comparing with vanadium oxides. In the present study, lepidocrocite VOOH hollow spheres with low crystallinity were synthesized through a template-free hydrothermal route. Diameter of VOOH hollow spheres ranged from 300nm to 500nm, and VOOH shell thickness reached 20nm on average. Electrochemical properties of VOOH hollow spheres as supercapacitor electrodes in aqueous electrolyte were developed and studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). Results revealed that VOOH hollow spheres featured capacitive behavior based on pseudocapacitance. Specific capacitance of 102F·g−1 at current density of 0.2A·g−1 was achieved. At current densities of 0.5, 1, 2.5 and 10A·g−1, specific capacitances measured 87, 68, 56 and 29F·g−1, respectively. Findings in present study proved that VOOH hollow spheres could be promising candidate as ideal material for supercapacitor electrodes.