High-Rate and Long-Term Cycle Stability of Li-S Batteries Enabled by Li2S/TiO2-Impregnated Hollow Carbon Nanofiber Cathodes

The high theoretical energy density of lithium-sulfur (Li-S) batteries makes them an alternative battery technology to lithium ion batteries. However, Li-S batteries suffer from low sulfur loading, poor charge transport, and dissolution of lithium polysulfide. In our study, we use the lithiated S, Li2S, as the cathode material, coupled with electrospun TiO2-impregnated hollow carbon nanofibers (TiO2-HCFs), which serve as the conductive agent and protective barrier for Li2S in Li-S batteries. TiO2-HCFs provide much improved electron/ionic conductivity and serve as a physical barrier, which prevents the dissolution of lithium polysulfides. The Li2S/TiO2-HCF composite delivers a discharge capacity of 851 mA h g(Li2S)(-1) at 0.1C and the bilayer TiO2-HCFs/Li2S/TiO2-HCF composite delivers a high specific capacity of 400 mA h g(Li2S)(-1) at 5C.