Strong Sulfur Binding with Conducting Magnéli-Phase TinO2n–1 Nanomaterials for Improving Lithium–Sulfur Batteries

Lithium–sulfur batteries show fascinating potential for advanced energy storage systems due to their high specific capacity, low-cost, and environmental benignity. However, the shuttle effect and the uncontrollable deposition of lithium sulfide species result in poor cycling performance and low Coulombic efficiency. Despite the recent success in trapping soluble polysulfides via porous matrix and chemical binding, the important mechanism of such controllable deposition of sulfur species has not been well understood. Herein, we discovered that conductive Magneli phase Ti4O7 is highly effective matrix to bind with sulfur species. Compared with the TiO2–S, the Ti4O7–S cathodes exhibit higher reversible capacity and improved cycling performance. It delivers high specific capacities at various C-rates (1342, 1044, and 623 mAh g–1 at 0.02, 0.1, and 0.5 C, respectively) and remarkable capacity retention of 99% (100 cycles at 0.1 C). The superior properties of Ti4O7–S are attributed to the strong adsorption of su...