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

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2022-04, Vol.18 (15), p.e2106716-n/a
• Main Authors: Wang, Zhouhao, Hu, Junping, Liu, Jing, Lim, Yew Von, Song, Haobin, Wang, Ye, He, Tingting, Huang, Chunlai, Yan, Xinwen, Zhang, Daohong, Huang, Shaozhuan
• Format: Article
• Language: English
• Subjects: Carbon nanotubes; Chemisorption; Decay rate; Diffusion layers; Electrochemistry; hypervalent iodine compounds; Interlayers; Iodine; Iodine compounds; Lewis acid; Lewis acid–base interaction; Lithium sulfur batteries; lithium−sulfur batteries; Nanoparticles; Nanotechnology; organic compounds; Oxygen atoms; Wettability
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202106716

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 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. A low‐cost, commercially available, and environmentally friendly hypervalent iodine compounds–iodosobenzene (PhIO) is developed to regulate the lithium polysulfides electrochemistry. PhIO plays a critical role in forming a strong Lewis acid–base interaction with polysulfides and enhancing the electrolyte wettability and Li+ conduction of separator, leading to highly improved electrochemical performance.