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

Abstract 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.