Nonpolar Alkanes Modify Lithium‐Ion Solvation for Improved Lithium Deposition and Stripping,Advanced Energy Materials

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Nonpolar Alkanes Modify Lithium‐Ion Solvation for Improved Lithium Deposition and Stripping
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2019-09-23 , DOI: 10.1002/aenm.201902116
Chibueze V. Amanchukwu ₁ , Xian Kong ₁ , Jian Qin ₁ , Yi Cui _{2,

3} , Zhenan Bao ₁

Affiliation

Lithium metal batteries have been plagued by the high reactivity of lithium. Reactive additives that can passivate the lithium metal surface and limit electrolyte accessibility to a fresh lithium surface have been widely explored, but can have limited utility with continuous consumption of the additive. In this work, an alternative strategy is explored. The use of nonreactive cosolvents such as nonpolar alkanes is studied and its is shown that hexane and cyclohexane addition to ether solvents (1,3‐dioxolane and 1,2‐dimethoxyethane) halves the nucleation and growth overpotentials for lithium deposition, increases the cell coulombic efficiency, improves the lithium deposition morphology, increases the electrolyte oxidative stability (>0.2 V), and doubles the cycle life—even when compared to a widely used fluorinated ether. The nonpolar alkanes modify the lithium‐ion solvation environment and reduce the solvation free energy; hence reducing the reaction barrier for lithium deposition. Exploration of nonpolar alkanes as part of the electrolyte mixture is a promising strategy for controlling metal deposition.

中文翻译：

非极性烷烃可修饰锂离子溶剂，以改善锂的沉积和剥离

锂金属电池一直受锂的高反应性困扰。可以钝化锂金属表面并限制电解质进入新的锂表面的反应性添加剂已得到广泛研究，但是随着添加剂的连续消耗，其实用性有限。在这项工作中，探索了一种替代策略。研究了非反应性助溶剂（如非极性烷烃）的使用，结果表明，将己烷和环己烷添加到醚溶剂（1,3-二氧戊环和1,2-二甲氧基乙烷）中可将锂沉积的成核和生长超电势减半，从而增加了电池库仑效率高，改善了锂的沉积形态，提高了电解质的氧化稳定性（> 0.2 V），并且使循环寿命延长了一倍，即使与广泛使用的氟化醚相比也是如此。非极性烷烃改变了锂离子的溶剂化环境并降低了溶剂化自由能。因此减少了锂沉积的反应势垒。探索非极性烷烃作为电解质混合物的一部分是控制金属沉积的有前途的策略。

更新日期：2019-11-06

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