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Effect of the Anion Activity on the Stability of Li Metal Anodes in Lithium‐Sulfur Batteries
Author(s) -
Cao Ruiguo,
Chen Junzheng,
Han Kee Sung,
Xu Wu,
Mei Donghai,
Bhattacharya Priyanka,
Engelhard Mark H.,
Mueller Karl T.,
Liu Jun,
Zhang JiGuang
Publication year - 2016
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201505074
Subject(s) - polysulfide , electrolyte , anode , materials science , lithium (medication) , inorganic chemistry , sulfide , metal , salt (chemistry) , electrochemistry , chemistry , organic chemistry , electrode , metallurgy , medicine , endocrinology
With the significant progress made in the development of cathodes in lithium‐sulfur (Li‐S) batteries, the stability of Li metal anodes becomes a more urgent challenge in these batteries. Here the systematic investigation of the stability of the anode/electrolyte interface in Li‐S batteries with concentrated electrolytes containing various lithium salts is reported. It is found that Li‐S batteries using LiTFSI‐based electrolytes are more stable than those using LiFSI‐based electrolytes. The decreased stability is because the N–S bond in the FSI − anion is fairly weak and the scission of this bond leads to the formation of lithium sulfate (LiSO x ) in the presence of polysulfide species. In contrast, in the LiTFSI‐based electrolyte, the lithium metal anode tends to react with polysulfide to form lithium sulfide (LiS x ), which is more reversible than LiSO x formed in the LiFSI‐based electrolyte. This fundamental difference in the bond strength of the salt anions in the presence of polysulfide species leads to a large difference in the stability of the anode‐electrolyte interface and performance of the Li‐S batteries with electrolytes composed of these salts. Therefore, anion selection is one of the key parameters in the search for new electrolytes for stable operation of Li‐S batteries.