Boosting lithium polysulfide conversion via TiO2-supported niobium catalyst for lithium sulfur battery

Abstract

Lithium sulfur (Li–S) batteries demonstrate enormous promise as a high-performance high-capacity energy storage solution but are severely limited by a low cycle life which stems from rapid capacity decay due to the low conductivity of lithium polysulfides and the poor kinetics of the lithium sulfur reduction reaction, which combined lead to the loss of active cathodic material. In this work, titanium oxide (TiO2) nanostructures are used as a host for a niobium catalyst which accelerates the conversion of polysulfides. Cells containing the TiO2-supported niobium catalyst demonstrated a very high level of stability, with a specific capacity decay rate of 0.045 % per cycle over 350 cycles. Li–S cells using this cathode host material also demonstrated high initial specific capacities, with initial capacities as high as 961 mAh g−1 at 0.2 C and 629 mAh g−1 at 3.0 C.