An enhanced polyethylene/polyetherimide composite separator for high-performance lithium-sulfur battery

The high performance and safety of lithium-sulfur (Li-S) batteries are the focus of research in recent years. The separator is an important part of the battery, whose performance stability directly affects the performance of the battery. What’s more, there are still many defects in the commercial polyolefin separator. In this work, a polyethylene/polyetherimide (PE/PEI) composite separator is designed by surface coating and non-solvent-induced phase separation (NIPS) method. The film breakage temperature and anti-puncture strength of the PE/PEI composite separator (181.96 °C, 7.90 N) are higher than those of the commercial PE separator (153.00 °C, 6.20 N), which will greatly ensure the safety problems caused by internal self-heating and external short circuit of Li-S batteries. The PE/PEI composite separator–based Li-S battery delivers a high initial specific capacity of 1265 mAh g−1 at 0.2 C and exhibits excellent rate capability compared with the commercial PE separator. Therefore, the PE/PEI composite separator is a candidate separator for the high-performance and high-safety Li-S battery.