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.