Hollow Carbon Nanoballs Coupled with Ultrafine TiO₂ Nanoparticles as Efficient Sulfur Hosts for Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries as among the most promising energy storage devices possess high theoretical capacity and energy density but suffer from the polysulfide dissolution, which hinders their practical application. Herein, we present a facile synthesis of hollow carbon nanoballs (HCNBs) anchored with ultrafine TiO₂ nanoparticles (TiO₂@HCNBs) in which the HCNBs with hollow interiors and graphitic crystallization accommodate the volume expansion of sulfur upon lithiation and improve the cathode conductivity, while the TiO₂ nanoparticles effectively trap the polysulfides through strong chemical bonding. Notably, the S@TiO₂@HCNBs with a high sulfur loading of ∼73 wt % demonstrate superior cycle performance at 0.5 C over 600 cycles with a slow capacity decay and deliver high specific capacities of 1217, 1013, 893, and 773 mA h/g at 0.1, 0.2, 0.5, and 1 C, respectively. The adsorption test clearly reveals the efficient suppression of the polysulfide shuttling owing to the spatial and chemical confinement of the TiO₂@HCNBs host.