A Li-Li2S4 battery with improved discharge capacity and cycle life at low electrolyte/sulfur ratios
A Li-Li2S4 battery with improved discharge capacity and cycle life at low electrolyte/sulfur ratios
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DOI：
10.1016/j.jpowsour.2019.01.029
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发表时间：
2019-02
影响因子：
9.2
通讯作者：
Chao Shen;Jianxin Xie;Mei Zhang;P. Andrei;Jim P. Zheng;M. Hendrickson;E. Plichta
中科院分区：
文献类型：
--
作者：
Chao Shen;Jianxin Xie;Mei Zhang;P. Andrei;Jim P. Zheng;M. Hendrickson;E. Plichta
锂硫（Li-S）电池有望取代锂离子电池成为下一代储能装置。然而，常规Li-S电池在低电解质/硫比下的操作相当具有挑战性，有许多障碍有待解决。本文以固态Li_2S_4为正极活性物质，构建了一种新型的Li-Li_2S_4电池。通过电化学阻抗谱的分析，我们发现在阴极中加入Li_2S_4（S）可以解决在贫电解液条件下所遇到的表面覆盖问题。在放电低平台上，Li_2S_4的溶解度并不决定放电容量。因此，具有84%的高硫含量和4.4 ml g-1的低E/S比的Li-Li 2S 4电池与常规Li-S电池相比提供了高得多的放电容量。此外，当控制Li_2S_4和Li_2S之间的Li-Li_2S_4电池循环时，实现了改善的循环保持。我们相信，所报道的结果为高能量密度Li-S电池的阴极开发开辟了新的方向。
Lithium sulfur (Li-S) batteries are promising candidates to replace lithium ion batteries as the next-generation energy storage devices. However, the operation of conventional Li-S batteries at low electrolyte/sulfur ratios is rather challenging with many obstacles to be addressed. In this work we use solid-state Li2S4as the cathode active material to construct a new type of Li-Li2S4battery. With the aid of electrochemical impedance spectrum, we find that the use of Li2S4(S)in the cathode alleviates the issue of surface coverage encountered under the lean electrolyte condition. We also find that the discharge capacity is not determined by the solubility of Li2S4on the lower plateau of discharge. Consequently, the Li-Li2S4cell with a high sulfur content of 84% and a low E/S ratio of 4.4 ml g−1delivered a much higher discharge capacity compared to a conventional Li-S cell. In addition, improved cycle retention was achieved when controlling the Li-Li2S4cell cycling between Li2S4and Li2S. We believe that the reported results open a new direction of cathode development for high energy density Li-S batteries.