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

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.