Polaron hopping-mediated dynamic interactive sites boost sulfur chemistry for flexible lithium-sulfur batteries

Abstract

Developing flexible and robust sulfur cathodes while boosting sulfur chemistry is a crucial enabler for the implementation of energy-dense flexible lithium-sulfur (Li-S) batteries. Here, we report an all-electrochem-active hybrid sulfur cathode by integrating nest-like O-defective RuO2 (RuO2-x) with sulfur to simultaneously realize decent flexibility, durability, and energy density. The mechanically robust RuO2-x with high electrical conductivity, active capacity contribution and high electrocatalytic activity is proved to be an ideal matrix to unlock high gravimetric and volumetric performances. Moreover, from jointly chemical and physical perspectives, it is confirmed that the polaron hopping-mediated dynamic interactive sites are formed in this RuO2-x/S system, which overcomes the reaction barrier and expedites Li-S chemistry. Impressively, the prototype pouch cells exhibit superb capacity retention under harsh bending conditions and harvest jointly high energy densities of 328 Wh kg−1 and 357 Wh L−1 under lean electrolyte condition, holding great promise for achieving energy-dense flexible Li-S batteries.