The Long‐Term Stability of KO2 in K‐O2 Batteries

The rechargeable K‐O2 battery is recognized as a promising energy storage solution owing to its large energy density, low overpotential, and high coulombic efficiency based on the single‐electron redox chemistry of potassium superoxide. However, the reactivity and long‐term stability of potassium su...

Full description

Saved in:
Bibliographic Details
Published in:Angewandte Chemie International Edition 2018-01, Vol.57 (5), p.1227-1231
Main Authors: Xiao, Neng, Rooney, Ryan T., Gewirth, Andrew A., Wu, Yiying
Format: Article
Language:English
Subjects:
analytical methods
Batteries
Disproportionation
Electrochemistry
electrolytes
Electron transfer
Energy storage
Flux density
Mass spectrometry
Mass spectroscopy
Peroxide
Potassium
potassium-oxygen batteries
Rechargeable batteries
Shelf life
Stability
Storage batteries
Superoxide
superoxide chemistry
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The rechargeable K‐O2 battery is recognized as a promising energy storage solution owing to its large energy density, low overpotential, and high coulombic efficiency based on the single‐electron redox chemistry of potassium superoxide. However, the reactivity and long‐term stability of potassium superoxide remains ambiguous in K‐O2 batteries. Parasitic reactions are explored and the use of ion chromatography to quantify trace amounts of side products is demonstrated. Both quantitative titrations and differential electrochemical mass spectrometry confirm the highly reversible single‐electron transfer process, with 98 % capacity attributed to the formation and decomposition of KO2. In contrast to the Na‐O2 counterparts, remarkable shelf‐life is demonstrated for K‐O2 batteries owing to the thermodynamic and kinetic stability of KO2, which prevents the spontaneous disproportionation to peroxide. This work sheds light on the reversible electrochemical process of K++e−+O2↔KO2. It's all about stability: The chemical stability of an ether‐based electrolyte, as well as the thermodynamic stability of KO2, contribute to the high coulombic efficiency and superior shelf‐life of K‐O2 cells.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201710454