TiO2 microbox/carbon nanotube composite-modified separator for high-performance lithium-sulfur batteries.

Mesoporous hollow TiO2 microboxes are synthesized by a two-step solvothermal method via CaTiO3 intermediate. Composite consisting of TiO2 microboxes and carbon nanotubes (CNT) is applied as a coating layer on conventional polymer separator for lithium-sulfur batteries. The cell using a modified separator exhibits enhanced cycling performance and rate capability. A discharge capacity of 852.3 mAh g−1 is achieved at 0.2 C after 200 cycles and more than 500 mAh g−1 of discharge capacity could be retained after 1000 cycles at 1 C, much better than the cells employing untreated or sole CNT-coated separator. Even at a high C-rate of 10 C, the cell with CNT-TiO2-coated separator could deliver a high specific discharge capacity of 561 mAh g−1. Such enhanced electrochemical performance is ascribed to the synergistic effect of CNT and TiO2 on suppressing shuttle reactions of lithium polysulfides. [ABSTRACT FROM AUTHOR]