A conductive and ordered macroporous structure design of titanium oxide-based catalytic cathode for lithium–sulfur batteries

Abstract

Abstract The application of lithium–sulfur (Li–S) batteries is hindered by the insulating characteristic of sulfur and slow reaction kinetics of lithium polysulfides. Here, we propose a three-dimensionally ordered macroporous (3DOM) structured conductive polar Ta-doped TiO2 framework with supported Co active site (CoTa@TiO2) to enhance the conversion kinetics of polysulfides. The 3DOM structure serves as an efficient sulfur host for the active sulfur through abundant pores and adsorption site. At the same time, the macropores can buffer the volume expansion of sulfur and enlarged mass transfer. The strong electrostatic attraction between Ti–O bond and polysulfide also promotes the adsorption of polysulfides. Moreover, the doped-Ta improves the conductivity of TiO2 by narrowing the band gap, whereas the supported Co can accelerate the catalytic transformation. Benefited from advanced structural design and synergistic effect of Co and Ta doped TiO2, the Li–S cell with 3DOM CoTa@TiO2 cathode exhibits an impressive areal capacity of 3.4 mAh cm−2 under a high sulfur loading of 5.1 mg cm−2. This work provides an alternative strategy for the development of carbon-based cathode materials for Li–S batteries.