Performance enhancement of Li-S battery with the anatase nano structured Fe doped TiO₂ as a robust interlayer

Li-S batteries are increasingly being investigated due to their high theoretical and practical energy density. During charge/discharge processes, reaction of elemental sulfur with Li⁺ ions leads to formation of soluble lithium polysulfides (LiPS) in the electrolyte, which diffuse toward the anode, known as the shuttle effect, which is the most serious problem about capacity degradation. One rational strategy to improve electrochemical performance of the cell relies on controlling the reactions on the coated separator surface so as to reduce LiPS shuttle between electrodes. In this work, Fe-doped (1 and 5 wt %) TiO₂ synthesized via sol-jel method. This novel coating on the glass fiber separator improved polysulfides trapping and enhanced electrical conductivity. The cell with 5 wt % Fe doped separator showed low capacity decay rate of 0.08% per cycle with superior capacity retention of 751 mAh g⁻¹ after 500 cycles at 1 C while the one with 1 wt % Fe doped showed capacity decay rate of 0.27% per cycle and capacity retention of 441 mAh g⁻¹ after 500 cycles at 1 C.