Sulfur Encapsulated in a TiO2-Anchored Hollow Carbon Nanofiber Hybrid Nanostructure for Lithium-Sulfur Batteries

A hollow carbon nanofiber hybrid nanostructure anchored with titanium dioxide (HCNF@TiO2) was prepared as a matrix for effective trapping of sulfur and polysulfides as a cathode material for Li-S batteries. The synthesized composites were characterized and examined by X-ray diffraction, nitrogen adsorption-desorption measurements, field-emission scanning electron microscopy, scanning transmission electron microscopy, and electrochemical methods such as galvanostatic charge/discharge, rate performance, and electrochemical impedance spectroscopy tests. The obtained HCNF@TiO2-S composite showed a clear core-shell structure with TiO2 nanoparticles coating the surface of the HCNF and sulfur homogeneously distributed in the coating layer. The HCNF@TiO2-S composite exhibited much better electrochemical performance than the HCNF-S composite, which delivered an initial discharge capacity of 1040mAhg(-1) and maintained 650mAhg(-1) after 200cycles at a 0.5C rate. The improvements of electrochemical performances might be attributed to the unique hybrid nanostructure of HCNF@TiO2 and good dispersion of sulfur in the HCNF@TiO2-S composite.