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Fast, Reversible Lithium Storage with a Sulfur/Long-Chain-Polysulfide Redox Couple

Authors

  • Yu-Sheng Su,

    1. Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (USA), Fax: (+1) 512-471-7681
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  • Dr. Yongzhu Fu,

    1. Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (USA), Fax: (+1) 512-471-7681
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  • Dr. Bingkun Guo,

    1. Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (USA)
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  • Dr. Sheng Dai,

    1. Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (USA)
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  • Prof. Arumugam Manthiram

    Corresponding author
    1. Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (USA), Fax: (+1) 512-471-7681
    • Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (USA), Fax: (+1) 512-471-7681
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Abstract

The cathodic reactions in Li–S batteries can be divided into two steps. Firstly, elemental sulfur is transformed into long-chain polysulfides (S8↔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.

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