Details

Autor(en) / Beteiligte

• Liang, Zhuojian
• Lu, Yi-Chun

Titel

Critical Role of Redox Mediator in Suppressing Charging Instabilities of Lithium–Oxygen Batteries

Ist Teil von

• Journal of the American Chemical Society, 2016-06, Vol.138 (24), p.7574-7583

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2016

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Redox mediators have been widely applied to reduce the charge overpotentials of lithium–oxygen (Li-O2) batteries. Here, we reveal the critical role of redox mediator in suppressing the charging instability of Li-O2 batteries. Using high temporal resolution online electrochemical mass spectrometry, we show that charging with redox mediators (using lithium bromide as a model system) significantly reduces parasitic gas evolution and improves oxygen recovery efficiency. Using redox mediator transforms the charge reactions from electrochemical pathways to chemical pathways, which unexpectedly bypasses the formation of highly reactive intermediates upon electro-oxidation of lithium peroxide (Li2O2). Such transformation reduces self-amplifying degradation reactions of electrode and electrolyte in Li-O2 cells. We further show that the improved stability associated with the redox mediator is much more pronounced at higher charging rates, owing to fast charge-transfer kinetics of the redox mediator. Together, we show that employing redox mediator not only reduces the charge overpotential but also suppresses side reactions of Li-O2 cells with improved charging rate. Our work demonstrates that transforming electro-oxidation of Li2O2 to chemical oxidation of Li2O2 is a promising strategy to simultaneously mitigate charging side reactions and achieve low overpotential for the Li-O2 batteries.