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New Insight into the “Shuttle Mechanism” of Rechargeable Lithium‐Sulfur Batteries
Author(s) -
Liu Jingdong,
Chen Hui,
Chen Wenda,
Zhang Yurong,
Zheng Yuanhui
Publication year - 2019
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201900420
Subject(s) - disproportionation , electrolyte , faraday efficiency , anode , electrochemistry , chemistry , lithium (medication) , sulfur , inorganic chemistry , cathode , chemical engineering , materials science , electrode , organic chemistry , catalysis , medicine , engineering , endocrinology
Lithium‐sulfur batteries have become an appealing candidate for low‐cost and high‐energy‐density power sources. It is generally believed that the “shuttle effect” in Li/S batteries causes serious performance degradation, such as low coulombic efficiency, sulfur loss, and so on. Here, we report a new mechanism based on the disproportionation reactions of polysulfides (PSs) to explain the rapid fading of capacity in Li/S batteries. Two different electrolytes (i. e., a carbonate‐based electrolyte and an ether‐based electrolyte) were adopted to study the disproportionation mechanism. We found that elemental sulfur was reprecipitated on the surface of the cathodes, forming a passive layer. The passive layer formed in the carbonate‐based electrolyte is much denser than that formed in the ether‐based electrolyte, resulting in the faster capacity fading in the carbonate‐based electrolyte. The simulation of cathodic peaks and anodic peaks in CV profiles confirms the disproportionation reaction of PSs in the ether‐based electrolyte. The electrochemical behavior of these Li/S batteries are well explained by an EC mechanism that involves an electron transfer reaction followed by a reversible disproportionation reaction. It is found that the disproportionation of PSs plays a more important role than the shuttle effect during the initial stage of the charge/discharge process.