α‐MnO2/RuO2 Heterostructure‐Modified Polypropylene Separator for High‐Performance Lithium–Sulfur Battery

Abstract Lithium–sulfur (Li–S) battery is a promising next‐generation energy storage system. However, the poor cyclability caused by the shuttle effect is still a key challenge for its practical application. Here, a polypropylene separator modified with α‐MnO 2 /RuO 2 heterostructure is presented to facilitate the transformation of lithium polysulfides (LiPSs) and optimize the rate‐determining step in both the reduction and oxidation processes of the sulfur electrode. The unique separator effectively suppresses the dissolution and shuttling of soluble LiPSs in Li–S batteries. The α‐MnO 2 /RuO 2 heterostructure modified separator with a Ru content of ≈8 wt% enables a high areal capacity of over 5.0 mAh cm −2 after 55 cycles at 0.2C in a Li–S coin cell, and the resultant pouch cell retains 78.2% of its initial capacity after 200 cycles at 0.1C, suggesting considerable potential for commercial applications. This work provides new insights into the regulation of electrochemical reactions in Li–S batteries.