Confining sulfur in intact freestanding scaffold of yolk-shell nanofibers with high sulfur content for lithium-sulfur batteries

Nanostructure design holds great potential in fabricating sulfur electrodes that host a high sulfur loading and still attain high electrochemical utilization for the developing of high-energy-density lithium-sulfur (Li-S) batteries. In this contribution, we introduce the yolk-shell structure into a freestanding carbon nanofibers film and construct a complete hollow yolk-shell TiO2/carbon [email protected]@[email protected] (TiO2[email protected]@[email protected]) composite. With inherent double conductive network and strong adsorption capability for polysulfides, the TiO2[email protected]@[email protected] composite can not only provide sufficient electrical contact for the insulating sulfur, but also effectively entrap polysulfides for prolonged cycle life. As a result, an excellent capacity retention ratio of 60.9% after 1000 cycles at 1 C as well as a high capacity of 688.5 mAh g−1 at 5 C rate is accomplished with the cells employing TiO2[email protected]@[email protected] as a cathode substrate for sulfur. Moreover, the TiO2[email protected]@[email protected] composite, with a high S mass loading of 9.5 mg cm−2, delivers a superb areal capacity of 8.2 mAh cm−2.