A Functional Separator Coated with Sulfonated Poly(Styrene-ethylene-butylene-styrene) to Synergistically Enhance the Electrochemical Performance and Anti-Self-Discharge Behavior of Li–S Batteries

Lithium sulfur battery is highly appealing for energy storage because of its high theoretical capacity and energy density. Nevertheless, as one of the pivotal problems, the shuttling of soluble polysulfide intermediates hinders its practical application. In this work, we employ an electronic conductive carbon material and a lithium ion conductive block polymer (lithium sulfonated poly­(styrene-ethylene-butylene-styrene), Li⁺-SSEBS) to fabricate a functional separator by a simple coating method. The functional coating on the PP separator exhibits excellent electronic conductivity for reactivating the active materials, good lithium ion conductivity for facilitating lithium ion transport, and great ionic selectivity for the suppressing polysulfide shuttle. With this separator, the battery shows a high initial discharge capacity of 1066 mAh g^–1 and excellent capacity retention of 762.7 mAh g^–1 after 350 cycles at 0.5 C. It also exhibits excellent rate performance with a high capacity of 750 mAh g^–1 at 2 C and good recovery capability. Furthermore, a correction strategy has been adopted to investigate the anti-self-discharge behavior of Li–S battery, which is more reasonable and precise than reported method. The results demonstrate that the SEBS-based functional separator can endow the enhanced electrochemical performance and anti-self-charge capability of Li–S battery.