Dual-Confinement Effect of Nanocages@Nanotubes Suppresses Polysulfide Shuttle Effect for High-Performance Lithium-Sulfur Batteries.

The shuttle effect of lithium polysulfides (LiPSs) severely hinders the development and commercialization of lithium-sulfur batteries, and the design of high-conductive carbon fiber-host material has become a key solution to suppress the shuttle effect. In this work, a unique Co/CoN-carbon nanocages@TiO-carbon nanotubes structure (NC@TiO-CNTs) is constructed using an electrospinning and nitriding process. Lithium-sulfur batteries using NC@TiO-CNTs as cathode host materials exhibit high sulfur utilization (1527 mAh g at 0.2 C) and can still maintain a discharge capacity of 663 mAh g at a high current density of 5 C, and the capacity loss is only 0.056% per cycle during 500 cycles at 1 C. It is worth noting that even under extreme conditions (sulfur-loading = 90%, surface-loading = 5.0 mg cm , and E/S = 6.63 µL mg), the lithium-sulfur batteries can still provide a reversible capacity of 4 mAh cm. Throughdensity functional theory calculations, it has been found that the Co/CoN heterostructures can adsorb and catalyze LiPSs conversion effectively. Simultaneously, the TiO can adsorb LiPSs and transfer Li selectively, achieving dual confinement for the shuttle effect of LiPSs (nanocages and nanotubes). The new findings provide a new performance enhancement strategy for the commercialization of lithium-sulfur batteries.