Titanium nitride hollow nanospheres with strong lithium polysulfide chemisorption as sulfur hosts for advanced lithium-sulfur batteries

Abstract

Lithium-sulfur batteries are promising electrochemical energy storage devices because of their high theoretical specific capacity and energy density. An ideal sulfur host should possess high conductivity and embrace the physical confinement or strong chemisorption to dramatically suppress the polysulfide dissolution. Herein, uniform TiN hollow nanospheres with an average diameter of ~160 nm have been reported as highly efficient lithium polysulfide reservoirs for high-performance lithium-sulfur batteries. Combining the high conductivity and chemical trapping of lithium polysulfides, the obtained S/TiN cathode of 70 wt.% sulfur content in the composite delivered an excellent long-life cycling performance at 0.5C and 1.0C over 300 cycles. More importantly, a stable capacity of 710.4 mAh·g−1 could be maintained even after 100 cycles at 0.2C with a high sulfur loading of 3.6 mg·cm−1. The nature of the interactions between TiN and lithium polysulfide species was investigated by X-ray photoelectron spectroscopy studies. Theoretical calculations were also carried out and the results revealed a strong binding between TiN and the lithium polysulfide species. It is expected that this class of conductive and polar materials would pave a new way for the high-energy lithium-sulfur batteries in the future.