Vanadium dioxide plates reduced graphene oxide as sulfur cathodes for efficient polysulfides trap in long-life lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are ideal for future energy storage owing to their rich resources and high theoretical energy density. However, the easy solubility of polysulfides and the insulating properties of elemental sulfur remain a challenge. Herein, graphene decorated with vanadium dioxide (VO2) plates was designed and manufactured as a cathode matrix for battery. The polar VO2 plates can anchor the polysulfide. At the same time, the conductive rGO network not only provides electrons transport channels for electrons/ions, but also accommodates the volume changes during cycling. The electrochemical tests show that the synthesized VO2/rGO/S composites with 75.4 wt% S have a high discharge capacity of 861mAhg-1 after 100 cycles at a current density of 0.1C. The assembled battery still provides a stable specific capacity of 493.4 mAhg-1 at a current density of 0.5C after 700 cycles and the discharge of 395.8 mAhg-1 was obtained at a current density of 1C over 1000 cycles. The capacity retention rate at 1C is higher than many other vanadium oxides reported. Therefore, the outstanding performance is ascribed to the fact that the VO2 plates can alleviate the shuttle effect of polysulfides and and the graphene layer forms a good conductive network for electron transport. This research provides an avenue for the development of long-life batteries.