Carbon coated halloysite nanotubes as efficient sulfur host materials for lithium sulfur batteries

Abstract

To impede the shuttle effect of lithium sulfur (LiS) batteries and improve the battery performance, carbon coated halloysite nanotubes (HNT@C) composites were synthesized and applied as sulfur host materials for LiS batteries. The unique one-dimensional tubular structure and abundant alumina-silicates components of HNT clay were synergistically utilized to physically confine and chemically adsorb lithium polysulfides, which could play important role to suppress the shuttle effect of polysulfides. Moreover, to solve the insulating issue of HNT, conducting carbon was deposited on the surface of HNT through polydopamine (PDA) coating and pyrolysis. The electrical conductivity of HNT@C host was thus significantly enhanced. As a result, the cycling stability and rate capability of the sulfur cathode were improved. In addition, the effect of carbon content on the properties of HNT@C composites and the electrochemical performance of the sulfur cathode were investigated. With carbon content of 3%, HNT@C hosted sulfur cathode delivered an initial discharge capacity of 922.7 mAh g−1 at current rate of 0.1C. Also, the capacity still retained about 82% after 500 cycles at 1C and the corresponding capacity decay is as low as 0.036% per cycle. This work can not only extend the application of HNT clay in energy storage but also provide a low-cost and promising HNT@C host material for advanced LiS batteries.