Free-standing TiO2 nanograssy tubular hybrid membrane for polysulfide trapping in Li–S battery

Abstract

During the growth of anodic TiO₂ nanotubes with a high layer thickness of greater than 20 μm, “nanograss” structures are typically formed on the outermost surface. This happens due to the fact that the engraving of the oxide tubes arises during prolonged exposure to an F- ion containing electrolyte. These TiO₂ nanotubular layers have a high aspect ratio with astonishing bundles of nanograss structures on the tube top and especially a high surface area with anatase crystallites in the tubes. By two-step anodization in synergy with the hybridization of a rubber polymer binder, freestanding nanotubular layers consisting of nanograssy surfaces with nano-crystalline particles in the tubes were successfully obtained. Under the highly efficient polysulfide trapping and electrolyte perturbation, this nanotubular hybrid membrane could deliver an enriched performance with a capacity of 618 mA h g⁻¹ after 100 cycles at 0.1C in Li–S batteries.