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

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 (approximate to 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 Li2S2/Li2S 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.

Automated summary

In this study, a hypervalent iodine compound named iodosobenzene (PhIO) was proposed to enhance the performance of Li-S batteries by regulating the electrochemistry of LiPSs. PhIO exhibited practical advantages such as low cost, commercial availability, environmental friendliness, and chemical stability. The results showed that the lone pair electrons of oxygen atoms in PhIO played a critical role in forming a strong Lewis acid-base interaction with terminal Li in LiPSs. Additionally, PhIO could be easily converted to nanoparticles and loaded on a carbon nanotube scaffold, resulting in an interlayer that obstructed LiPSs penetration, enhanced electrolyte wettability and Li+ conduction. The Li-S battery based on the PhIO@CNT interlayer exhibited stable cycling and excellent rate performance.