One-pot sonochemical synthesis of hierarchical MnWO4 microflowers as effective electrodes in neutral electrolyte for high performance asymmetric supercapacitors

Abstract

In this article, manganese tungstate (MnWO4) microflowers as electrode materials for high performance supercapacitor applications are prepared by a one-pot sonochemical synthesis. The crystalline structure and morphology of MnWO4 microflowers are characterized through X-ray diffraction, field emission scanning electron microscopy. The electrochemical properties of the MnWO4 microflowers are investigated using cyclic voltammograms, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The MnWO4 microflowers as electrode materials possess a maximum specific capacitance of 324 F g−1 at 1 mA cm−2 in the potential window from 0 to +1 V and an excellent cycling stability of 93% after 8000 cycles at a current density of 3 mA cm−2. An asymmetric supercapacitor device is fabricated using the MnWO4 and iron oxide (Fe3O4)/multi-wall carbon nanotube as the positive and negative electrode materials, it can be cycled reversibly at a potential window at 1.8 V. The fabricated ASC device can deliver a high energy density of 34 Wh kg−1 at a power density of 500 W kg−1 with cycling stability of 84% capacitance retained after 3000 cycles. The above results demonstrate that MnWO4 microflowers can be used as promising high capacity electrode materials in neutral electrolyte for high performance supercapacitors.