Mesoporous graphitic carbon-TiO₂ composite microspheres produced by a pilot-scale spray-drying process as an efficient sulfur host material for Li-S batteries

Mesoporous graphitic carbon-TiO₂ composite microspheres are fabricated by a facile process and used as an effective sulfur host material for Li-sulfur batteries (LSBs). Composite microspheres are several microns in size and with uniform size distributions that contained maltodextrin, iron nitrate, and TiO₂ nanocrystals are formed using a pilot-scale spray-drying process, then transform into graphitic carbon-TiO₂ composite microspheres with numerous empty nanovoids by a single post-treatment step and subsequent etching of metallic iron. The composite carbon microspheres not only have high pore volumes after the removal of metallic iron, providing sufficient spaces for the infiltration of sulfur, but also increase electronic conductivity in electrodes due to the graphitic carbon. Consequently, a high specific capacity of 516 mA h g⁻¹ at a current density of 5 C and a reversible capacity of 599 mA h g⁻¹ after 600 cycles at a current density of 1 C are achieved, indicating the excellent capability of the material for use in energy storage devices. The structure of the mesoporous graphitic carbon-TiO₂ composite microspheres make them suitable for use as a host material in sulfur cathodes and can significantly improve the electrochemical performances of LSBs.