TiO2 nanowire array as a polar absorber for high-performance lithium-sulfur batteries

The rechargeable lithium-sulfur battery is recognized as a next-generation lithium-ion battery due to its exceptionally high energy density and low cost. Unfortunately, the high dissolution of polysulfides and the low conductivity of sulfur and lithium sulfide lead to a fast capacity decay and a poor specific capacity of the sulfur cathode, which impedes the further development of lithium-sulfur batteries. To overcome these issues, we propose a 3D binder-free collector via in situ-grown polar TiO2 nanowires on carbon-nanofibers, which can successfully suppress the “shuttle effect” of polysulfides and improve the electron conductivity of the sulfur cathode. The prepared TiO2-nanowires arrays provide a large surface area for sulfur loading and a convenient path for electron transfer. These characteristics result in a high ion diffusion capacity of up to 699 mA h g−1 with an excellent coulombic efficiency, higher than 98.5% after 300 cycles at 1.0 C, and a capacity decay as low as 0.075% per cycle. In addition, the strong chemical binding interaction between the polysulfides and TiO2 was directly observed by in situ UV/Vis spectroscopy.