Fast, reversible lithium storage with a sulfur/long-chain-polysulfide redox couple

Yu Sheng Su, Yongzhu Fu, Bingkun Guo, Sheng Dai, Arumugam Manthiram*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

52 Scopus citations

Abstract

The cathodic reactions in Li-S batteries can be divided into two steps. Firstly, elemental sulfur is transformed into long-chain polysulfides (S 8↔Li2S4), which are highly soluble in the electrolyte. Next, long-chain polysulfides undergo nucleation reaction and convert into solid-state Li2S2 and Li2S (Li2S4↔Li2S) by slow processes. As a result, the second-step of the electrochemical reaction hinders the high-rate application of Li-S batteries. In this report, the kinetics of the sulfur/long-chain-polysulfide redox couple (theoretical capacity=419 mA h g -1) are experimentally demonstrated to be very fast in the Li-S system. A Li-S cell with a blended carbon interlayer retains excellent cycle stability and possesses a high percentage of active material utilization over 250 cycles at high C rates. The meso-/micropores in the interlayer are responsible for accommodating the shuttling polysulfides and offering sufficient electrolyte accessibility. Therefore, utilizing the sulfur/long-chain polysulfide redox couple with an efficient interlayer configuration in Li-S batteries may be a promising choice for high-power applications. More juice: The kinetics of the sulfur/long-chain polysulfide redox couple (S 8↔Li2S4; theoretical capacity= 419 mA h g-1) are experimentally demonstrated to be very fast in the Li-S system. A Li-S battery with a blended-carbon interlayer retains excellent cycle stability and high discharge capacity over 250 cycles at 10 C and 15 C rates. The meso-/micropores in the interlayer are responsible for storing the migrating polysulfides and offering sufficient electrolyte accessibility.

Original languageEnglish
Pages (from-to)8621-8626
Number of pages6
JournalChemistry - A European Journal
Volume19
Issue number26
DOIs
StatePublished - 24 Jun 2013

Keywords

  • carbon interlayer configuration
  • cyclic voltammetry
  • energy storage
  • lithium-sulfur batteries
  • polysulfides
  • porous carbon materials
  • sulfur

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