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Nonflammable Nitrile Deep Eutectic Electrolyte Enables High-Voltage Lithium Metal Batteries

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posted on 09.03.2020, 16:35 authored by Zhenglin Hu, Fang Xian, Ziyang Guo, Chenglong Lu, Xiaofan Du, Xiangyang Cheng, Shu Zhang, Shanmu Dong, Guanglei Cui, Liquan Chen
Nonflammable functional electrolytes with remarkably interfacial compatibility toward both lithium anodes and high-voltage cathodes are considered as the ultimate pursuit for rechargeable lithium metal battery. For this target, we report a dual-anion deep eutectic solution (D-DES) based on elaborately selected combination of nitrile and functional lithium salts. The interactions of succinonitrile with cation/anion are highlighted by in situ/ex situ measurements, which endow D-DES with excellent ionic conductivity and significantly enhanced interface stability. By using this D-DES, constant Li|Li cycling over 1 year (>10,000 h) under a Li capacity of 5 mA h cm–2 can be achieved. The capacity retention is still over 70% with a high charging voltage of 4.7 V for 500 cycles in LiCoO2|Li battery. Pouch cells with high areal capacity close to practical application also deliver superior safe performance. This study paves a new pathway for designing high-safety electrolyte and boosts the practical application of high-voltage lithium metal battery.