Issue 4, 2022

A localized high concentration electrolyte for 4 V-class potassium metal batteries

Abstract

Rechargeable potassium-metal batteries (PMBs) meet the need for high energy density because the potassium (K) metal anode has the highest specific capacity (687 mA h g−1) among anode materials, but electrolytes that are stable with both the highly reactive K metal anode and high-voltage cathodes remain a serious challenge. Here, we report a localized high concentration electrolyte consisting of potassium bis(fluoroslufonyl)imide (KFSI) in diethylene glycol dimethyl ether (G2) with 1,1,2,2-tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (TFETFE) (1 : 1.5 : 1.5) as a diluent for 4 V-class PMBs. This new electrolyte shows unprecedented cycling stability in K|Prussian blue (PB) batteries with a capacity retention of 83% over 2000 cycles (over 10 months) at a charge cut-off voltage of 4.3 V. Higher voltage tolerance of 4.4 V is also confirmed in the PMBs for 300 cycles. This study provides an avenue to design electrolytes for high-energy PMBs in the future.

Graphical abstract: A localized high concentration electrolyte for 4 V-class potassium metal batteries

Supplementary files

Article information

Article type
Communication
Submitted
20 jan 2022
Accepted
01 mar 2022
First published
02 mar 2022
This article is Open Access
Creative Commons BY-NC license

Energy Adv., 2022,1, 191-196

A localized high concentration electrolyte for 4 V-class potassium metal batteries

W. Xu, H. Wang, Y. Gao, Y. Wei, H. Zhang, C. Gao, F. Kang and D. Zhai, Energy Adv., 2022, 1, 191 DOI: 10.1039/D2YA00015F

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