A high-performance potassium metal battery using safe ionic liquid electrolyte

Hao Sun, Peng Liang, Guanzhou Zhu, Wei Hsuan Hung, Yuan Yao Li, Hung Chun Tai, Cheng Liang Huang, Jiachen Li, Yongtao Meng, Michael Angell, Chang An Wang, Hongjie Dai

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

Potassium secondary batteries are contenders of next-generation energy storage devices owing to the much higher abundance of potassium than lithium. However, safety issues and poor cycle life of K metal battery have been key bottlenecks. Here we report an ionic liquid electrolyte comprising 1-ethyl-3-methylimidazolium chloride/AlCl3/KCl/potassium bis(fluorosulfonyl) imide for safe and high-performance batteries. The electrolyte is nonflammable and exhibits a high ionic conductivity of 13.1 mS cm−1 at room temperature. A 3.6-V battery with K anode and Prussian blue/reduced graphene oxide cathode delivers a high energy and power density of 381 and 1,350 W kg−1, respectively. The battery shows an excellent cycling stability over 820 cycles, retaining ∼89% of the original capacity with high Coulombic efficiencies of ∼99.9%. High cyclability is also achieved at elevated temperatures up to 60 °C. Uniquely, robust K, Al, F, and Cl-containing passivating interphases are afforded with this electrolyte, which is key to superior battery cycling performances.

Original languageEnglish
Pages (from-to)27847-27853
Number of pages7
JournalProceedings of the National Academy of Sciences of the United States of America
Volume117
Issue number45
DOIs
StatePublished - 10 Nov 2020

Keywords

  • Potassium battery | ionic liquid electrolyte | Prussian blue | high-safety battery | high-energy-density battery

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