Fabricating efficient polysulfide barrier via ultrathin tantalum pentoxide grown on separator for lithium–sulfur batteries

Abstract

The infamous shuttle effect of polysulfides is the main obstacle severely hindering the practical application of Li–S battery. To address such issue, we fabricated a homogeneous ultrathin Ta2O5 layer deposited on separators via typical pulsed laser deposition. The polar surface of the Ta2O5 coating can not only serve as a barrier inhibiting polysulfides shuttling due to strong chemisorption, but also accelerate the redox kinetics of immobilized polysulfides, which was demonstrated by density functional theory calculations and electrochemical experiments. With the Ta2O5 modified separator, the cell using a cathode prepared by nitrogen-doped graphene achieves good rate capability in contrast to the one with bare commercialized separator. Specifically, even at a high areal sulfur loading of 5.27 mg cm−2, the cell can deliver a high initial areal capacity of 5.3 mAh cm−2 and retains 4.2 mAh cm−2 over 60 cycles, which exceeds commercial lithium-ion batteries (4 mAh cm−2), suggesting its actual application possibility.