Unusual Stability of Acetonitrile-Based Superconcentrated Electrolytes for Fast-Charging Lithium-Ion Batteries
Unusual Stability of Acetonitrile-Based Superconcentrated Electrolytes for Fast-Charging Lithium-Ion Batteries
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DOI：
10.1021/ja412807w
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发表时间：
2014-04-02
影响因子：
15
通讯作者：
Yamada, Atsuo
中科院分区：
文献类型：
--
作者：
Yamada, Yuki;Furukawa, Keizo;Yamada, Atsuo
快速充电和高压锂离子电池以及下一代先进电池（例如，Li-O-2体系）。乙腈（AN）溶液是最有前途的电解质之一，具有非常高的化学稳定性和氧化稳定性以及高的离子电导率，但其还原稳定性低是阻碍其广泛应用的关键问题。在此，我们报告了增强的还原稳定性的超浓缩AN溶液（>4摩尔dm（-3））。将其应用到电池电解质中，我们首次证明了在易还原的AN溶剂中可逆锂嵌入石墨电极中。此外，反应动力学比目前使用的商业电解质快得多。第一性原理计算结合光谱分析表明，特有的还原稳定性来自于这种超浓溶液所特有的改性前线轨道特征，其中所有溶剂和阴离子与Li+阳离子配位形成阴离子和Li+阳离子的流体聚合物网络。
The development of a stable, functional electrolyte is urgently required for fast-charging and high-voltage lithium-ion batteries as well as next-generation advanced batteries (e.g., Li-O-2 systems). Acetonitrile (AN) solutions are one of the most promising electrolytes with remarkably high chemical and oxidative stability as well as high ionic conductivity, but its low stability against reduction is a critical problem that hinders its extensive applications. Herein, we report enhanced reductive stability of a superconcentrated AN solution (>4 mol dm(-3)). Applying it to a battery electrolyte, we demonstrate, for the first time, reversible lithium intercalation into a graphite electrode in a reduction-vulnerable AN solvent. Moreover, the reaction kinetics is much faster than in a currently used commercial electrolyte. First-principle calculations combined with spectroscopic analyses reveal that the peculiar reductive stability arises from modified frontier orbital characters unique to such superconcentrated solutions, in which all solvents and anions coordinate to Li+ cations to form a fluid polymeric network of anions and Li+ cations.