Hollow porous SiO2 nanobelts containing sulfur for long-life lithium–sulfur batteries

Abstract

Sulfur is a type of a fascinating cathode material with a high theoretical specific capacity of 1672 mA h g⁻¹. However, its rapid capacity fading on charge/discharge cycling still hinders its practical implementation owing to the high solubility of polysulfide intermediates and their side-reactions with the Li anode for lithium–sulfur batteries (LSBs). In this study, a new type of hollow porous SiO₂ nanobelt was fabricated by a simple template-directed methodology. The hollow porous SiO₂ nanobelts not only serve as scaffolds to house sulfur but also as a polysulfide reservoir for LSBs. Due to their unique structural and compositional features, the hollow porous SiO₂ nanobelts/S composite cathodes exhibit substantially enhanced cycling stability and superior coulombic efficiency compared to the pristine sulfur cathode. The SiO₂ nanobelts/S composite with 50 wt% sulfur delivers an initial discharge capacity of 685 mA h g⁻¹ and 534 mA h g⁻¹ after 70 cycles at 0.1C with an average coulombic efficiency of about 100%. These results suggest that the SiO₂ nanobelts/S composites hold great promise for high-efficiency and long-term service life LSBs.