Toward in-situ protected sulfur cathodes by using lithium bromide and pre-charge

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Feixiang Wu - , Georgia Institute of Technology (Author)
  • Sören Thieme - , Fraunhofer Institute for Material and Beam Technology (Author)
  • Anirudh Ramanujapuram - , Georgia Institute of Technology (Author)
  • Enbo Zhao - , Georgia Institute of Technology (Author)
  • Christine Weller - , TUD Dresden University of Technology (Author)
  • Holger Althues - , Fraunhofer Institute for Material and Beam Technology (Author)
  • Stefan Kaskel - , Chair of Inorganic Chemistry I, Fraunhofer Institute for Material and Beam Technology (Author)
  • Oleg Borodin - , United States Army Research Laboratory (Author)
  • Gleb Yushin - , Georgia Institute of Technology (Author)

Abstract

Lithium-sulfur (Li-S) batteries suffer from the dissolution of its intermediate charge products (polysulfides) in organic electrolytes, which limits the utilization, rate performance and cycling stability of S cathode materials. Formation of protective surface coatings on S cathodes may effectively overcome such a challenge. Here, we explored a simple, low cost, and widely applicable method that offers in-situ formation of a protective coating on the S-based cathode by using lithium bromide (LiBr) as a novel electrolyte additive. Quantum chemical (QC) studies suggested that pre-cycling a S cathode at high potentials is needed to oxidize the Br- and induce formation of DME(-H) radicals, which are involved in the formation of a polymerized protective layer of a solid electrolyte interphase (SEI) on a S cathode at high potentials. Experimental studies with a LiBr additive confirmed that 3 pre-cycles in a voltage range of 2.5–3.6 V are sufficient to achieve the formation of a robust Li ion permeable SEI on the cathode, effectively preventing the dissolution of polysulfides into electrolyte. As a result, almost no degradation was observed within 200 cycles, compared to more than 40% of capacity loss in the benchmark control cells without LiBr or the pre-cycles. Post-mortem analysis on both the cathode and anode sides of the LiBr-comprising cells further provided evidence for the in-situ SEI formation on the cathode and the lack of polysulfides’ re-precipitation. In addition, such studies showed smooth surface on the cycled Li metal anode, in contrast to the rough Li SEI with dendrites and polysulfides in the benchmark cells.

Details

Original languageEnglish
Pages (from-to)170-179
Number of pages10
JournalNano energy
Volume40
Publication statusPublished - 10 Aug 2017
Peer-reviewedYes

Keywords

Sustainable Development Goals

Keywords

  • Electrolyte additive, Lithium bromide, Polysulfides, Shell, Sulfur