Polysulfide Regulation by Hypervalent Iodine Compounds for Durable and Sustainable Lithium–Sulfur Battery

Abstract

Abstract Herein, a type of hypervalent iodine compound—iodosobenzene (PhIO)—is proposed to regulate the LiPSs electrochemistry and enhance the performance of Li‐S battery. PhIO owns the practical advantages of low‐cost, commercial availability, environmental friendliness and chemical stability. The lone pair electrons of oxygen atoms in PhIO play a critical role in forming a strong Lewis acid–base interaction with terminal Li in LiPSs. Moreover, the commercial PhIO can be easily converted to nanoparticles (≈20 nm) and uniformly loaded on a carbon nanotube (CNT) scaffold, ensuring sufficient chemisorption for LiPSs. The integrated functional PhIO@CNT interlayer affords a LiPSs‐concentrated shield that not only strongly obstructs the LiPSs penetration but also significantly enhances the electrolyte wettability and Li + conduction. The PhIO@CNT interlayer also serves as a “vice current collector” to accommodate various LiPSs and render smooth LiPSs transformation, which suppresses insulating Li 2 S 2 /Li 2 S layer formation and facilitates Li + diffusion. The Li−S battery based on PhIO@CNT interlayer (6 wt% PhIO) exhibits stable cycling over 1000 cycles (0.033% capacity decay per cycle) and excellent rate performance (686.6 mAh g −1 at 3 C). This work demonstrates the great potential of PhIO in regulating LiPSs and provides a new avenue towards the low‐cost and sustainable application of Li−S batteries.