A rational VO2 nanotube/graphene binary sulfur host for superior lithium-sulfur batteries.

Lithium-sulfur batteries engage widespread attention due to their high theoretical capacity in recent years. However, the shuttle effect and some other issues are not thoroughly solved at present. Here, VO 2 nanotubes with relatively higher redox potential (than sulfur) are in situ compounded with graphene (G) for constructing an effective VO 2 /G binary sulfur host. In such a binary host, VO 2 nanotubes are able to chemically adsorb soluble lithium polysulfides (LiPSs) and optimize their electrochemical conversion kinetics, thereby, inhibiting the shuttle effect of LiPSs. In addition, the presence of graphene can be capable of improving the electronic conductivity of the cathode material and reducing the polarization of the whole electrode. Impressively, the final fabricated VO 2 /G/S electrode delivers large specific capacity, good rate performance and stable cycling performance, which holds great potential for different applications. One-step hydrothermal method has been used to synthesis VO 2 nanotubes grown on graphene (VO 2 /G), in which, VO 2 nanotubes with strong chemical polarity and high electrochemical redox potential play the key roles for chemically adsorption of soluble lithium polysulfide and accelerating the conversion process between long-chain lithium polysulfide and short-chain Li 2 S 2 /Li 2 S, and thus effectively inhibit the "shuttle effect" during charge and discharge process. Image 1 [ABSTRACT FROM AUTHOR]