Three-dimensional TiO2-B nanotubes/carbon nanotubes intertwined network as sulfur hosts for high performance lithium - sulfur batteries

The rechargeable lithium sulfur batteries are investigated as a promising energy storage system. Various materials as the host of sulfur have been applied to improve the performance of lithium sulfur batteries. However, the poor conductivity of sulfur and polysulfides shuttle effect result in poor cycling performance and lower specific capacity. Here, a novel chemical and physical entrapment strategy to improve the electrochemical performance is introduced by designing and synthesizing a 3D network composite which consists of intertwined TiO2-B nanotubes and carbon nanotubes as the sulfur hosts. In this unique structure, carbon nanotubes serve as the long-range conductive network which facilitates the transfer of electrons during redox reaction. Theoretical calculations reveal that TiO2-B provides a strong chemical binding for polysulfides, and each TiO2-B nanotube as an independent reaction chamber provides an efficient barrier to restrict the shuttling of the polysulfides. Specifically, the electrodes exhibit an ultralow capacity fading of 0.05% per cycle over 800 discharge/charge cycles, and a high specific capacity of 580 inAh g(-1) at 1C rate after 300 cycles even with high areal sulfur loading of 3.2 mg cm(-2).