A versatile functionalized ionic liquid to boost the solution-mediated performances of lithium-oxygen batteries

• Published in: Nature communications Vol. 10; no. 1; pp. 602 - 10
• Main Authors: Zhang, Jinqiang, Sun, Bing, Zhao, Yufei, Tkacheva, Anastasia, Liu, Zhenjie, Yan, Kang, Guo, Xin, McDonagh, Andrew M., Shanmukaraj, Devaraj, Wang, Chengyin, Rojo, Teofilo, Armand, Michel, Peng, Zhangquan, Wang, Guoxiu
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 05.02.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 140/131; 147/135; 639/301/299/886; 639/301/299/891; 639/4077/4079/891; 639/638/161/891; 639/638/675; Anodic protection; Batteries; Cycles; Electric vehicles; Electrochemical analysis; Electrochemistry; Electrolytes; Energy storage; Humanities and Social Sciences; Ionic liquids; Ions; Liquid bearings; Lithium; Lithium batteries; multidisciplinary; Oxygen; Peroxide; Protectors; Reaction mechanisms; Science; Science (multidisciplinary); Solid electrolytes
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-08422-8

Due to the high theoretical specific energy, the lithium–oxygen battery has been heralded as a promising energy storage system for applications such as electric vehicles. However, its large over-potentials during discharge–charge cycling lead to the formation of side-products, and short cycle life. Herein, we report an ionic liquid bearing the redox active 2,2,6,6-tetramethyl-1-piperidinyloxy moiety, which serves multiple functions as redox mediator, oxygen shuttle, lithium anode protector, as well as electrolyte solvent. The additive contributes a 33-fold increase of the discharge capacity in comparison to a pure ether-based electrolyte and lowers the over-potential to an exceptionally low value of 0.9 V. Meanwhile, its molecule facilitates smooth lithium plating/stripping, and promotes the formation of a stable solid electrolyte interface to suppress side-reactions. Moreover, the proportion of ionic liquid in the electrolyte influences the reaction mechanism, and a high proportion leads to the formation of amorphous lithium peroxide and a long cycling life (> 200 cycles). In particular, it enables an outstanding electrochemical performance when operated in air. Li-O 2 batteries are promising candidates for the next generation of rechargeable batteries, but the side reactions and poor cycling stability limit their applications. Here, the authors show a versatile ionic liquid with functional groups that can address both issues for cells operated in oxygen and air.