Polysulfide Stabilization: A Pivotal Strategy to Achieve High Energy Density Li–S Batteries with Long Cycle Life,Advanced Functional Materials

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Polysulfide Stabilization: A Pivotal Strategy to Achieve High Energy Density Li–S Batteries with Long Cycle Life
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2017-12-18 , DOI: 10.1002/adfm.201704987
Yuqing Chen _{1,

2} , Hongzhang Zhang _{1,

3} , Wenbin Xu ₁ , Xiaofei Yang _{1,

2} , Ying Yu _{1,

2} , Xianfeng Li _{1,

3} , Huamin Zhang _{1,

3}

Affiliation

The disproportionation of polysulfide (PS) is a long‐neglected and vital issue that causes the fast capacity fading of Li–S batteries. Based on the hard and soft acids and bases (HSAB) theory, a large size N‐methyl‐N‐ethyl pyrrolidinium (MEP⁺) cation is proposed to complex and stabilize the PS in electrolyte. The disproportionation of PS is successfully suppressed by this simple method, thereby avoiding the precipitation of sulfur in the electrolyte and reducing the loss of the active materials. The mutual interaction mechanism between MEP⁺ and S_n²⁻ in electrolyte is comprehensively investigated and verified for the first time, via both density functional theory (DFT) calculation and experimental characterization. It enables the 5000 mA h Li–S batteries (soft package type) to achieve initial specific energy over 300 Wh kg⁻¹ and maintain over 65% after 100 charge/discharge cycles at 1/20 C, while merely 24% is remained at 59 cycles without MEP⁺. This interesting finding is believed to shed light on the further development of Li–S batteries.

中文翻译：

多硫化物稳定化：实现高能量密度，长寿命锂电池的关键策略

聚硫化物（PS）的歧化是一个长期被忽视且至关重要的问题，它导致Li-S电池的容量快速下降。基于硬酸和软酸和碱（HSAB）理论，提出了大尺寸的N-甲基-N-乙基吡咯烷鎓（MEP ⁺）阳离子，以络合和稳定电解质中的PS。通过这种简单的方法成功地抑制了PS的歧化，从而避免了硫在电解质中的沉淀并减少了活性物质的损失。MEP ⁺与S _n²⁻之间的相互作用机制通过密度泛函理论（DFT）计算和实验表征，首次对电解质中的碳纳米管进行了全面的研究和验证。它使5000 mA h Li–S电池（软包装类型）能够在300 Wh kg ^-1以上实现初始比能，并在1/20 C下进行100次充电/放电循环后保持超过65％的能量，而在24h时仅保留24％的能量。没有MEP ^+的59个循环。据信这一有趣的发现为锂-硫电池的进一步发展提供了启示。

更新日期：2017-12-18

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