KOH selective etching strategy to construct novel TiO2-wrapped sulfur as cathode for lithium–sulfur batteries

Abstract

Lithium–sulfur batteries (LSBs) have become the “new darling” in the field of energy storage given their high energy density and low cost. However, volume expansion and shuttle effect of lithium polysulfides (LiPSs) are obstacles to the development of LSBs. Herein, we propose a KOH selective etching strategy to remove V2O5 phase in dual-phase TiO2/V2O5. Then, a novel TiO2-wrapped sulfur cathode material for LSBs is designed. Initially, the structure of anatase and rutile TiO2 can be controlled via selective etching. Moreover, the porous TiO2 phase can fully encapsulate LiPSs and provide sufficient loading space for sulfur active materials. The TiO2-wrapped sulfur cathode with double effect (chemisorption and physisorption) shows considerable electrochemical performance. The specific capacities are 1144.68, 1017.84, and 881.16 mAh g−1 when the current density is 0.1, 0.2, and 0.5 C, respectively. The retention of discharge capacity is as high as 81.16% after 140 cycles.