Controlling {001} Facet Exposure in TiO Nanoflakes for Enhanced Polysulfide Trapping in Lithium-Sulfur Batteries

Abstract

The development of lithium sulfur (Li-S) battery is considerably limited due to the "shuttle effect" of the soluble lithium polysulfides (LiPSs). The introduction of modified separator at the cathode side is proved to be one of the effective solutions. In this work, TiO nanoflakes (TiO-NFs) with (001) exposed facets were successfully prepared to block the shuttle of LiPSs and improve the redox kinetics at the same time. The employment of the polydopamine (PDA) was confirmed to be helpful on inhibiting the morphology change of TiO-NFs during magnesiothermic reduction reaction process. Through visible adsorption, symmetric cells and Li2S nucleation testing, the TiO-NFs is confirmed to possess excellent adsorption and catalytic activity on LiPSs. The assembled batteries by using TiO-NFs@PP modified separator exhibit the initial capacity of 1492 mAh g -1 at 0.1 C. When the current density reached 1 C, the capacity decay per cycle revealed as low as 0.067% after 1000 cycles. Even under the high sulfur loading of 5.5 mg cm -2 , a high areal capacity of 4 mAh cm -2 can be maintained after 100 cycles at 0.2 C. This work provided new methods for the design and preparation of non-stoichiometric metal oxides with specific exposed facets toward high-performance Li-S batteries.