Operando UV/vis Spectroscopy Providing Insights into the Sulfur and Polysulfide Dissolution in Magnesium–Sulfur Batteries,ACS Energy Letters

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Operando UV/vis Spectroscopy Providing Insights into the Sulfur and Polysulfide Dissolution in Magnesium–Sulfur Batteries
ACS Energy Letters ( IF 19.3 ) Pub Date : 2021-11-19 , DOI: 10.1021/acsenergylett.1c02152
Joachim Häcker ₁ , Duc Hien Nguyen _{1,

2} , Tobias Rommel ₁ , Zhirong Zhao-Karger ₃ , Norbert Wagner ₁ , K. Andreas Friedrich _{1,

4}

Affiliation

The magnesium–sulfur battery represents a promising post-lithium system with potentially high energy density and improved safety. However, just as all metal–sulfur systems, it is plagued with the polysulfide shuttle leading to active material loss and surface layer formation on the anode. To gain further insights, the present study aims to shed light on the dissolution characteristics of sulfur and polysulfides in glyme-based electrolytes for magnesium–sulfur batteries. Therefore, operando UV/vis spectroscopy and imaging were applied to survey their concentration in solution and the separator coloration during galvanostatic cycling. The influence of conductive cathode additives (carbon black and titanium nitride) on the sulfur retention and cycling overpotentials were investigated. Thus, valuable insights into the system’s reversibility and the benefit of additional reaction sites are gained. On the basis of these findings, a reduction pathway is proposed with S₈, S₆^2–, and S₄^2– being the present species in the electrolyte, while the dissolution of S₈^2– and S₃^•– is unfavored. In addition, the evolution of the sulfur species concentration during an extended rest at open-circuit voltage was investigated, which revealed a three-staged self-discharge.

中文翻译：

Operando 紫外/可见光谱法提供对镁硫电池中硫和多硫化物溶解的洞察

镁硫电池代表了一种很有前途的后锂系统，具有潜在的高能量密度和更高的安全性。然而，就像所有金属-硫系统一样，它也受到多硫化物穿梭的困扰，导致活性材料损失和阳极表面层的形成。为了获得进一步的见解，本研究旨在阐明硫和多硫化物在镁硫电池的甘醇二甲醚基电解质中的溶解特性。因此，应用操作紫外/可见光谱和成像来调查它们在溶液中的浓度和恒电流循环过程中的隔膜着色。研究了导电阴极添加剂（炭黑和氮化钛）对硫保留和循环过电位的影响。因此，获得了对系统可逆性和额外反应位点益处的宝贵见解。在这些发现的基础上，提出了一种还原途径，其中 S_如图8所示，电解液中存在S ₆^2-和S ₄^{2- ，而S}₈^2-和S ₃^•-的溶解是不利的。此外，还研究了在开路电压下长时间静止期间硫物质浓度的演变，这揭示了三阶段的自放电。

更新日期：2022-01-14

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