Can an Inorganic Coating Serve as Stable SEI for Aqueous Superconcentrated Electrolytes?
Can an Inorganic Coating Serve as Stable SEI for Aqueous Superconcentrated Electrolytes?
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DOI：
10.1021/acsenergylett.1c01097
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发表时间：
2021-06-28
影响因子：
22
通讯作者：
Grimaud, Alexis
中科院分区：
文献类型：
--
作者：
Droguet, Lea;Hobold, Gustavo M.;Grimaud, Alexis
为水基锂离子电池开发稳定、保形的固体电解质中间相（SEI）一直是人们期待已久的梦想，以支持无毒且环保的储能技术的发展。为了实现这一目标，最近引入了水性超浓缩电解质，因为其独特的溶剂化结构允许在负极形成富含 LiF 的 SEI 层，从而赋予界面稳定性。然而，尽管越来越多的证据表明钝化性能较差且运行时水减少，但这种富含 LiF 的 SEI 的内在稳定性从未被测量过。在这项工作中，LiF保形层被涂覆在锂电极上，并通过结合溶解度测量、原位显微镜和气相色谱法研究了它们对超浓缩水性电解质的反应性。我们证明，使用超浓缩电解质会大大降低 LiF 的溶解度。然而，由于不存在自钝化，这种层在水性环境中本质上不稳定，但在有机电解质中稳定。比较不同的界面，我们得出结论，由无机涂层制成的人工SEI不适合防止水性体系中的水反应性。
Developing a stable, conformal solid electrolyte interphase SEI) for aqueous-based Li-ion batteries has been a long-awaited dream to support the development of nontoxic and eco-friendly energy storage technologies. Toward that goal, aqueous superconcentrated electrolytes were recently introduced as their unique solvation structure allows for forming a LiF-rich SEI layer at the negative electrode, imparting the stability to the interface. However, the intrinsic stability of such LiF-rich SEI was never measured, despite growing evidence of poor passivation properties and water reduction upon operation. In this work, LiF conformal layers were coated onto lithium electrodes, and their reactivity toward superconcentrated aqueous electrolytes was studied by combining solubility measurements, in situ microscopy, and gas chromatography. We demonstrate that the use of superconcentrated electrolytes drastically reduces the solubility of LiF. However, such layer is intrinsically unstable in aqueous environments, but stable in organic electrolytes, owing to the absence of self-passivation. Comparing different interfaces, we conclude that an artificial SEI made of an inorganic coating is not suitable for preventing water reactivity in aqueous systems.