Surface and catalyst driven singlet oxygen formation in Li-O2 cells

Aleksej Samojlov, David Schuster, Jürgen Kahr, Stefan A. Freunberger*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Large overpotentials upon discharge and charge of Li-O2 cells have motivated extensive research into heterogeneous solid electrocatalysts or non-carbon electrodes with the aim to improve rate capability, round-trip efficiency, and cycle life. These features are equally governed by parasitic reactions, which are now recognized to be caused by formation of the highly reactive singlet oxygen (1O2). However, the link between the presence of electrocatalysts and 1O2 formation in metal-O2 cells is unknown. Here, we show that, compared to pristine carbon black electrodes, a representative selection of electrocatalysts or non-carbon electrodes (noble metal, transition metal compounds) may both slightly reduce or severely increase the 1O2 formation. The individual reaction steps, where the surfaces impact the 1O2 yield are deciphered, showing that 1O2 yields from superoxide disproportionation as well as the decomposition of traces of H2O2 are sensitive to catalysts. Transition metal compounds in general are prone to increase 1O2. The results highlight the importance of 1O2 in metal-O2 cells and to use a comprehensive set of metrics to judge the impact of catalysts on reversibility.

Original languageEnglish
Article number137175
JournalElectrochimica Acta
Volume362
DOIs
Publication statusPublished - 1 Dec 2020

Keywords

  • Electrocatalysis
  • Li-O batteries
  • Peroxide
  • Singlet oxygen
  • Superoxide

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry

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