Electrocatalysis on Separator Modified by Molybdenum Trioxide Nanobelts for Lithium–Sulfur Batteries

Abstract Lithium–sulfur batteries (LSBs) have been regarded as the supreme feasible future generation energy storage system for high‐energy applications due to the exceptional‐specific energy density of 2600 Wh kg −1 and theoretical‐specific capacity of 1675 mAh g −1 . Nevertheless, some key challenges which are linked with polysulfide shuttling and sluggish kinetics of polysulfide conversion are the main obstacles in the high electrochemical performance of LSBs. Here, a molybdenum trioxide (MoO 3 ) nanobelt catalytic layer is fabricated on the separator to solve these issues. The MoO 3 layer shows strong chemical interaction with polysulfides by successfully blocking the polysulfides on the separator from shuttling and significantly accelerates the redox reaction of polysulfide conversion. Furthermore, the randomly arranged layers of MoO 3 nanobelts possess enough porous networks that provide effective space for electrolyte infiltration and facile pathway for fast ion transportation. The resultant LSBs exhibit a very high initial capacity of 1377 mAh g −1 . After 200 cycles at 0.5 C, the capacity is 684.4 mAh g −1 with the fading rate of only 0.251% per cycle. Additionally, the MoO 3 modification provides good surface protection of lithium anode and depresses the lithium anode degradation.