Preparation and Capacitive Behavior of Dandelion-Likeγ-MnO2Nanofibre/Activated Carbon Microbeads Composite for the Application of Supercapacitor

Dandelion-like γ-manganese dioxide (γ-MnO2) nanofibre/activated carbon microbeads (ACMBs) composite is prepared by an in situ coating technique. The structure and morphology of the composite are characterized by scanning electron microscopy and X-ray diffraction. The results show that γ-MnO2 nanofibre is uniformly encapsulated on the surface of ACMB, and the composite finally becomes a dandelion-like microbead. Cyclic voltammetry, galvanostatic current charge/discharge, and cycle life measurements are used to evaluate the electrochemical behaviors of the composite. Since the composite is able to undergo pseudofaradic charge transfer reactions and hereto contributes together with the double-layer effect to the total capacitance of the material, the specific capacitance of the composite is as high as 375.9 F g-1 at a scan rate of 1 mV s-1, which is significantly higher than the pure ACMB. Besides, the capacitance retention of the supercapacitor using the composite as electrode-active material keeps still 93% after 1000 cycles