Preparation and Performance of Porous Polyetherimide/Al2O3 Separator for Enhanced Lithium-Sulfur Batteries

Graphical Better apart : A porous polyetherimide (PEI)/Al 2 O 3 separator for lithium-sulfur batteries is prepared through non-solvent-induced phase separation. PEI/Al 2 O 3 has a dense structure on one side and the other side offers a loose and porous structure. This special morphology has a physical blocking effect on polysulfides. Also, the PEI/Al 2 O 3 separator possesses excellent thermal stability and ionic conductivity of practical significance. The assembled cell with the prepared PEI/Al 2 O 3 separator exhibits a better cycling performance than that with the commercial Celgard 2320 separator. As an important component of lithium-sulfur batteries, the separator has a critical role in battery safety and the corresponding electrochemical performance. In this study, a high-performance polyetherimide (PEI)/Al 2 O 3 separator was prepared through the non-solvent-induced phase separation (NIPS) technique. It was demonstrated that the existence of Al 2 O 3 affects the morphology, thermal stability, electrolyte uptake, ionic conductivity, and electrochemical properties of the PEI/Al 2 O 3 separator. The results indicate that PEI/Al 2 O 3 separators containing 5 and 6 wt % Al 2 O 3 possess high porosity, good electrolyte uptake, excellent thermal stability (thermal shrinkage ratio is only 0.78 % even at a high temperature of 200 °C), and ionic conductivity of practical significance (up to 2.20 mS ⋅ cm −1 ). Consequently, the assembled cell with the prepared PEI/Al 2 O 3 separator exhibits a better cycling performance (724.9 mA h g −1 after 200 cycles at 0.2 C) than that with the commercial Celgard 2320 separator. Therefore, the PEI/Al 2 O 3 separator prepared by NIPS is a potential separator candidate for high-safety and high-performance dischargeable lithium-sulfur batteries.