Insight into the reaction mechanism of sulfur chains adjustable polymer cathode for high-loading lithium-organosulfur batteries

Small molecules with adjustable sulfur atoms in the confined structure were acted as precursor for the synthesis of polymer cathodes for lithium-organosulfur batteries. Among them, poly(diallyl tetrasulfide) (PDATtS) delivered a high capacity of 700 mAh g(-1), stable capacity retention of 85% after 300 cycles, high areal capacity similar to 4 mAh cm(-2) for electrode with up to 10.3 mg cm(-2) loading. New insight into the reaction mechanism of PDATtS electrode that radicals arisen from the homolytic cleavage of S - S bond in PDATtS reacted with Li+ to generate thiolates (RSLi) and insoluble lithium sulfides (Li2S) or lithium disulfide (Li2S2) was clearly verified by in-situ UV/Vis spectroscopy, nuclear magnetic resonance (NMR) studies and density-functional theory (DFT) calculations. Therefore, based on the unique reaction mechanism, problems of rapid capacity fading due to the formation of soluble polysulfide intermediates and their serious shuttle effect in conventional lithium-sulfur (Li-S) batteries was totally avoided, realizing the dendrite-free lithium sulfur batteries. This study sets new trends for avenues of further research to advance Li - S battery technologies. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

This study utilized small molecules with adjustable sulfur atoms in a confined structure as precursors for polymer cathodes, achieving dendrite-free lithium sulfur batteries with a unique reaction mechanism. This breakthrough avoided rapid capacity fading in conventional Li-S batteries and sets new trends for further research in Li-S battery technologies.