Improving Electrochemical Stability and Low‐Temperature Performance with Water/Acetonitrile Hybrid Electrolytes,Advanced Energy Materials

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Improving Electrochemical Stability and Low‐Temperature Performance with Water/Acetonitrile Hybrid Electrolytes
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2019-11-22 , DOI: 10.1002/aenm.201902654
Jiawei Chen ₁ , Jenel Vatamanu ₂ , Lidan Xing ₁ , Oleg Borodin ₂ , Huiyang Chen ₁ , Xiongcong Guan ₁ , Xiang Liu ₁ , Kang Xu ₂ , Weishan Li ₁

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Although the “water‐in‐salt” electrolyte has significantly expanded the electrochemical stability window of aqueous electrolytes from 1.23 to 3 V, its inevitable hydrogen evolution under 1.9 V versus Li⁺/Li prevents the practical use of many energy‐dense anodes. Meanwhile, its liquidus temperature at 17 °C restricts its application below ambient temperatures. An advanced hybrid electrolyte is proposed in this work by introducing acetonitrile (AN) as co‐solvent, which minimizes the presence of interfacial water at the negatively charged electrode surface, and generates a thin and uniform interphase consisting of an organic outer layer based on nitrile (CN) and sulfamide (R‐S‐N‐S) species and an inner layer rich in LiF. Such an interphase significantly suppresses water reduction and expands the electrochemical stability window to an unprecedented width of 4.5 V. Thanks to the low freezing point (−48 °C) and low viscosity of AN, the hybrid electrolyte is highly conductive in a wide temperature range, and enables a LiMn₂O₄/Li₄Ti₅O₁₂ full cell at both ambient and sub‐ambient temperatures with excellent cycling stability and rate capability. Meanwhile, such a hybrid electrolyte also inherits the nonflammable nature of aqueous electrolyte. The well‐balanced merits of the developed electrolyte make it suitable for high energy density aqueous batteries.

中文翻译：

水/乙腈杂化电解质提高电化学稳定性和低温性能

尽管“盐包水”电解质已将水性电解质的电化学稳定性窗口从1.23 V显着扩大到3 V，但在1.9 V的条件下，与Li ⁺相比，不可避免的析氢/ Li阻止了许多能量密集型阳极的实际使用。同时，其液相线温度为17°C，限制了其在环境温度以下的应用。在这项工作中，通过引入乙腈（AN）作为共溶剂，提出了一种先进的混合电解质，该方法可最大程度地减少带负电的电极表面的界面水的存在，并产生薄而均匀的界面，该界面由基于腈的有机外层组成（CN）和磺酰胺（R‐S‐N‐S）物种以及内层富含LiF。这种中间相可显着抑制水分减少，并将电化学稳定性窗口扩大到前所未有的4.5 V宽度。由于低凝固点（-48°C）和AN的低粘度，混合电解质在很宽的温度范围内具有高导电性，并启用LiMn ₂O ₄ / Li ₄ Ti ₅ O ₁₂全电池在环境温度和低于环境温度下均具有出色的循环稳定性和倍率性能。同时，这种混合电解质还继承了水性电解质的不可燃性。所开发电解质的均衡特性使其适用于高能量密度的水性电池。

更新日期：2020-01-22

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