In Situ X-ray Absorption Spectroscopic Investigation of the Capacity Degradation Mechanism in Mg/S Batteries,Nano Letters

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In Situ X-ray Absorption Spectroscopic Investigation of the Capacity Degradation Mechanism in Mg/S Batteries
Nano Letters ( IF 9.6 ) Pub Date : 2019-04-01 00:00:00 , DOI: 10.1021/acs.nanolett.8b05208
Yan Xu _{1,

2} , Yifan Ye ₃ , Shuyang Zhao ₄ , Jun Feng ₃ , Jia Li ₄ , Hao Chen ₅ , Ankun Yang ₅ , Feifei Shi ₅ , Lujie Jia ₆ , Yang Wu ₆ , Xiaoyun Yu ₅ , Per-Anders Glans-Suzuki ₃ , Yi Cui ₅ , Jinghua Guo ₃ , Yuegang Zhang _{1,

6}

Affiliation

The Mg/S battery is attractive because of its high theoretical energy density and the abundance of Mg and S on the earth. However, its development is hindered by the lack of understanding to the underlying electrochemical reaction mechanism of its charge–discharge processes. Here, using a unique in situ X-ray absorption spectroscopic tool, we systematically study the reaction pathways of the Mg/S cells in Mg(HMDS)₂–AlCl₃ electrolyte. We find that the capacity degradation is mainly due to the formation of irreversible discharge products, such as MgS and Mg₃S₈, through a direct electrochemical deposition or a chemical disproportionation of intermediate polysulfide. In light of the fundamental understanding, we propose to use TiS₂ as a catalyst to activate the irreversible reaction of low-order MgS_x and MgS, which results in an increased discharging capacity up to 900 mAh·g^–1 and a longer cycling life.

中文翻译：

Mg / S电池容量衰减机理的原位X射线吸收光谱研究

Mg / S电池之所以具有吸引力，是因为其理论能量密度高，并且地球上的Mg和S含量很高。但是，由于对其充放电过程的基本电化学反应机理缺乏了解，阻碍了它的发展。在这里，我们使用独特的原位X射线吸收光谱仪，系统地研究了Mg（HMDS）₂ -AlCl ₃电解质中Mg / S细胞的反应途径。我们发现容量下降主要是由于不可逆放电产物的形成，例如MgS和Mg ₃ S ₈通过直接电化学沉积或中间多硫化物的化学歧化来实现。根据基本理解，我们建议使用TiS ₂作为催化剂来激活低级MgS _x和MgS的不可逆反应，从而使放电容量增加至900 mAh·g ^–1，并延长循环寿命。

更新日期：2019-04-01

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