Effect of the Anion Activity on the Stability of Li Metal Anodes in Lithium-Sulfur Batteries

Ruiguo Cao, Junzheng Chen, Kee Sung Han, Wu Xu, Donghai Mei, Priyanka Bhattacharya, Mark H. Engelhard, Karl T. Mueller, Jun Liu, Ji Guang Zhang

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

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 (LiSOx) 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 (LiSx), which is more reversible than LiSOx 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.

Original languageEnglish (US)
Pages (from-to)3059-3066
Number of pages8
JournalAdvanced Functional Materials
Volume26
Issue number18
DOIs
StatePublished - May 10 2016

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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