An insight into the electrochemical performance of nanostructured V2O5 in aqueous neutral electrolytes and fabrication of 2V, high energy density, symmetric supercapacitor

The exceptional redox characteristics, simple methods of synthesis, low cost and wide range of oxidation states of transition metal oxides like V2O5 have made them highly sought after electrode materials for supercapacitors. In the present study, V2O5 nanostructures prepared via a facile microwave-assisted method is used as the electrode material. The electrochemical performances of this electrode material is analysed in four different aqueous neutral electrolytes. The nature of the ions present in the electrolytes are found to have a significant influence on the performance of the electrode, achieving the highest specific capacitance values in KCl electrolyte while highest potential window and stability in Na2SO4 electrolyte. The symmetric supercapacitor fabricated using the Na2SO4 electrolyte exhibits a specific capacitance value of 82.35 F g(-1) and a specific energy of 45.75 Wh kg(-1) at a specific power of 1000 W kg(-1). Moreover, the device retains 70 % of its initial capacitance even after 10,000 charge-discharge cycles at a current density of 5 A g(-1). An asymmetric supercapacitor is also fabricated using KCl electrolyte after optimizing the mass-ratio of positive and negative electrodes using Ragone plot simulator. The asymmetric supercapacitor exhibits a specific capacitance of 34 F g(-1) with an energy density and power density of 11 Wh kg(-1) and 775 W kg(-1) respectively. The present study summarizes the effect of different neutral electrolytes on the electrochemical performance of V2O5 nanostructured electrodes. The physiochemical properties of ions such as solvation, diffusion and mobility, and their influence on the electrochemical behaviour are also taken in to account to explain the observed electrode performance.