Recycled MnO2Nanoflowers and Graphene Nanosheets for Low-Cost and High Performance Asymmetric Supercapacitor

Electrochemical materials, namely MnO(2)and reduced graphene oxide (rGO), have been prepared in diverse morphologies (nanoflowers and nanosheets, respectively). Different physical and chemical characterizations were conducted to investigate the material structure and morphology. Electrochemical properties of these materials have been studied comprehensively using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy to evaluate their suitability for supercapacitive energy storage. MnO(2)nanoflowers were obtained by recycling spent batteries. The single electrodes of MnO(2)nanoflowers and rGO nanosheets exhibit a high specific capacitance of 208.5 F g(-1)and 145 F g(-1), respectively. Therefore, an asymmetrical supercapacitor was fabricated from both materials and electrochemically evaluated. It shows a superb supercapacitive performance of up to 2.0 V in Na2SO4. The asymmetrical supercapacitor produces a high specific capacitance (177.6 F g(-1)), energy density (24.7 Wh kg(-1)) and stability (95.2% over 4000 cycles). The findings recommend using MnO(2)nanoflowers and rGO nanosheets as an asymmetric supercapacitor.