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

Journal Article · Tue Mar 29 04:00:00 EDT 2016 · Advanced Functional Materials

DOI:https://doi.org/10.1002/adfm.201505074· OSTI ID:1282474

Cao, Ruiguo ^[1]; Chen, Junzheng ^[1]; Han, Kee Sung ^[2]; Xu, Wu ^[1]; Mei, Donghai ^[3]; Bhattacharya, Priyanka ^[1]; Engelhard, Mark H. ^[2]; Mueller, Karl T. ^[4]; Liu, Jun ^[1]; Zhang, Ji-Guang ^[1]

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1. Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA
2. Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA
3. Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA
4. Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Department of Chemistry, Pennsylvania State University, University Park, PA 16802 USA

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 we report the systematic investigation of the stability of the anode/electrolyte interface in Li-S batteries with concentrated electrolytes containing various lithium salts. 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, even the weakest bond (C-S) in the TFSI- anion is stronger than the N-S bond in the FSI- anion. 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 LiTFSI-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.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1282474
• Report Number(s): PNNL-SA-114711; 48164; 48379; KC0208010
• Journal Information: Advanced Functional Materials, Journal Name: Advanced Functional Materials Journal Issue: 18 Vol. 26; ISSN 1616-301X
• Publisher: Wiley
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory
Li-sulfur battery
anion
concentrated electrolyte
lithium anode
lithium salt