Synthesis and capacitive performance of globular MnO₂ flowers anchored graphene composites

Abstract

A new type globular MnO2 flowers anchored graphene composites was synthesized via redox reactions among potassium permanganate/ethanol/graphene. The crystalline structure, chemical component, and microstructure of the composites were determined by XRD, TG, SEM/TEM and BET analysis. The electrochemical test demonstrates the globular MnO2 material possesses excellent specific capacitance while poor rate capability and cycling stability. By means of anchoring these globular MnO2 flowers onto graphene, the specific capacitance of graphene is significantly improved. Meanwhile, rate capability and cycling stability of the globular MnO2 material can be promoted remarkably. In 0.5mol/L K2SO4 electrolyte, the specific capacitance of the composites reaches as high as 295F·g-1 at 2mV·s-1, and maintains at 102F·g-1 even at a high scan rate of 1000mV·s-1.An outstanding capacitance retention of 96.3% is achieved for the composites after 1000 cycles at 100mV·s-1. It demonstrates the globular MnO2 flowers anchored graphene composites is a very potential electrode material for supercapacitors.

Keywords

• globular MnO₂ flower
• composites
• supercapacitor
• energy storage electrode materials