▎ 摘　　要

The high solubility of polysulfides in the electrolyte, together with the resulting poor cycling performance, is one of the main obstacles to the industrial production and use of lithium-sulfur (Li-S) batteries. We have developed a novel hybrid and dense separator coating that greatly improves the cycling and rate performance of the battery. The coating is fabricated by mono-dispersed Li4Ti5O12 (LTO) nanospheres uniformly embedded in graphene layers. In this hybrid dense coating, the LTO nanospheres have a high chemical affinity for polysulfides and an excellent ionic conductivity to produce highly efficient ionic conductive channels, while the graphene layers play twin roles as a physical barrier for polysulfides and an upper current collector. The unique hybridization guarantees a very dense coating that does not significantly add the volume of the battery and meanwhile achieves an ideal combination of an effective barrier for polysulfide diffusion with a fast ion transport. For a normal coating, a loose and very thick structure is needed to meet these requirements. Cells using a pure sulfur electrode with the dense coating separator show an ultra-high rate performance (709 mA hg(-1) at 2 C and 1408 mA h g(-1) at 0.1 C) and an excellent cycling performance (697 mA h g(-1) after 500 cycles at 1 C with 85.7% capacity retention). The easy achieving of such excellent performance indicates the possibility of producing an industrially practical Li-S battery.