The catalytic activity of manganese dioxide supported on graphene promoting the electrochemical performance of lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have become a research hotspot due to their high energy density , environment friendliness and low-cost. But commercial applications are hampered by rapid capacity fading and low sulfur content. Herein, the composite of integrating manganese oxide on graphene was prepared by a facile redox reaction between potassium permanganate (KMnO 4 ) and graphene in acidic aqueous solution to solve the problems of the Li-S batteries. X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis show that sulfur was uniformity coated on G/MnO 2 composite. TG indicated that the G/MnO 2 /S composites contained 76.56   wt% active sulfur. The prepared cathode of G/MnO 2 /S composites exhibited excellent rate performance and cycle stability. At a high rate of 1   C, its maximum discharge capacity reached 908   mA   h   g −1 and its average capacity decreasing rate was only 0.105%/cycle when running over 500   cycles. The interaction mechanism of MnO 2 with polysulfides was investigated by adsorption tests and XPS analysis. The excellent electrochemical performance might be due to a combination of adsorption or catalytic properties of MnO 2 , and the conductivity network of graphene.