Asymmetric separator integrated with ferroelectric-BaTiO3 and mesoporous-CNT for the reutilization of soluble polysulfide in lithium-sulfur batteries

Abstract In this study we report the use of a hybrid separator coated with mesoporous multi-walled carbon nanotubes (MWCNTs) and ferroelectric BaTiO3 (BTO) as a “conductive scaffold” and polysulfide barrier for high-performance lithium-sulfur batteries. The effectiveness of the hybrid separator was verified by using a high sulfur cathode (70%). The modified separator effectively limited the migration of lithium polysulfides, improved the integrity of the sulfur cathode, and provided a conductive channel for ion and electron transport. As a result, the cell utilizing the separator coated with MWCNT and BTO (AHT-MWCNT–BTO) exhibited excellent electrochemical performance and rate kinetics, delivering a high initial discharge capacity of 1388.6 mAh g−1 at 0.1 C-rate, corresponding to 83% sulfur utilization in the electrode. Additionally, the cycling performance revealed a 77% capacity retention of the initial value after 100 repeated cycles at 0.5 C-rate. Furthermore, even at a high current density of 2.0 C, the cell with the AHT-MWCNT–BTO-coated separator delivered a discharge capacity of 422.8 mAh g−1 after 350 cycles, besides significantly increasing the sulfur utilization and effectively improving the electrochemical conversion of trapped polysulfides. These results reveal the exceptional potential of AHT-MWCNT–BTO-coated separators in the development of next generation high-performance lithium–sulfur batteries.